US20060254284A1 - Seat air conditioning unit - Google Patents

Abstract

In an air conditioning unit for a seat, a duct forms a first outlet port through which air is blown to a seat surface and a second outlet port for discharging air. A heat exchanger unit having a thermoelectric effect element is disposed in the duct. An air volume control device is disposed in a duct to control a ratio of air introduced to the first outlet port to air introduced in an inlet port of the duct. In a draft mode, the air volume control device is operated such that the volume of air introduced to the first outlet port is larger than that in a normal mode. In a predetermined condition, the air volume control device is operated in the draft mode and an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate in the heat exchanger unit is smaller than that in the normal mode.

Description

CROSS REFERENCE TO RELATED APPLICATION
• This application is based on Japanese Patent Applications No. 2005-138609 filed on May 11, 2005, No. 2006-46506 filed on Feb. 23, 2006, and No. 2006-46507 filed on Feb. 23, 2006, the disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION
• The present invention relates to a seat air conditioning unit that blows air from a seat surface.
BACKGROUND OF THE INVENTION
• According to a seat air conditioning unit disclosed in Japanese Unexamined Patent Publication No. 10-44756, a temperature of air to be blown from a surface of a seat is increased or reduced through a heat exchanger unit having a Peltier element so as to improve a feeling of a passenger seating on the seat. A flow of air is produced by a blower unit and is introduced to the heat exchanger unit. In the heat exchanger unit, a first heat exchanger is disposed on a heat absorbing side of the Peltier element and a second heat exchanger is disposed on a heat radiating side of the Peltier element. Air that has passed through the first heat exchanger is blown from the seat surface, and air that has passed through the second heat exchanger is discharged to an outside of the seat.
• In the seat air conditioning unit, when humidity between the passenger and the seat exceeds a predetermined level, an air mix door is opened so that the air passing through the first heat exchanger and the air passing through the second heat exchanger are mixed. The mixed air is blown from the seat surface. Accordingly, a moist feeling of the passenger reduces.
• Also, there is another seat air conditioning unit that blows air inside of a passenger compartment from a seat surface without controlling a temperature of the air through a heat exchanger unit. In general, when the seat surface is hot, e.g., in summer, it is required to cool the seat surface in a short time (a transitional quick cooling operation) so as to improve a seat feeling. On the contrary, when the seat surface is very cold e.g., in winter, it is required to heat the seat surface in a short time (a transitional quick heating operation) to improve the seat feeling.
• Regarding the former seat air conditioning unit, in the transitional state in which the quick cooling operation or the quick heating operation is required, the air that has passed through the first heat exchanger is blown from the seat surface. However, the air that has passed through the second heat exchanger is discharged to the outside of the seat as a waste heat. Therefore, it is difficult to blow a sufficient volume of air from the seat surface in the transitional state.
• In the latter seat air conditioning unit, the air is not discharged as the waste heat even in the transitional state. Therefore, a sufficient volume of air is blown from the seat surface. However, the temperature of the air to be blown from the seat surface is not controlled. That is, the air to be blown from the seat surface has a temperature equal to a temperature of the air inside the passenger compartment. Therefore, it is difficult to provide a sufficient cooling effect, particularly, in a normal operation.
SUMMARY OF THE INVENTION
• The present invention is made in view of the foregoing matter, and it is an object of the present invention to provide a seat air conditioning unit having a draft effect by blowing the large volume of air in a transitional state and a cooling or heating effect in a normal operation.
• According to a first aspect of the present invention, an air conditioning unit for a seat has a duct, a heat exchanger unit, and an air volume control device. The duct defines a passage space, an inlet port through which air is introduced in the passage space, and a first outlet port through which the air is blown from a seat surface. The passage space of the duct separates into a first passage communicating with the first outlet port and a second passage space defining a second outlet port for discharging air to an outside of the seat.
• The heat exchanger unit has a thermoelectric effect element, a first heat exchanger and a second heat exchanger. The thermoelectric effect element has a first side and a second side. One of the first side and the second side defines a heat absorbing side and the other one of the first side and the second side defines a heat radiating side. The heat radiating side and the heat radiating side are switched according to a flow direction of an electric current in the thermoelectric effect element. The first heat exchanger is disposed adjacent to the first side for performing heat exchange with air flowing in the first passage. The second heat exchanger is disposed adjacent to the second side for performing heat exchange with air flowing in the second passage.
• The air volume control device is disposed in the duct for changing a ratio of air introduced to the first outlet port to the air introduced in the inlet port. In a normal mode, the thermoelectric effect element is energized and the air volume control device is operated so that air passing through the first heat exchanger is introduced to the first outlet port and air passing through the second heat exchanger is discharged through the second outlet port. In a draft mode, the air volume control device is operated so that the ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode. In a predetermined condition, the air volume control device is operated in the draft mode and an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate in the first and second heat exchangers is smaller than that in the normal mode.
• Accordingly, the ratio of air blown from the first outlet port to the air introduced in the inlet port is changed between the draft mode and the normal mode. Namely, in the draft mode, the volume of air blown from the seat surface is larger than that in the normal mode. Therefore, a draft effect improves. On the other hand, in the normal mode, the air blown from the first outlet port has an air conditioning effect through the first heat exchanger. Further, in the predetermined condition, the heat exchange rate in the heat exchanger unit is smaller than that in the normal mode, and the air volume control device is operated in the draft mode. Accordingly, the large volume of air is blown from the seat surface with reduced power consumption in the draft mode.
• According to a second aspect of the present invention, the duct further defines a bypass passage for allowing the air introduced in the inlet port to bypass the first heat exchanger and the second heat exchanger. The bypass passage communicates with the first outlet port. The air volume control device is disposed in the duct for controlling the volume of air flowing in the bypass passage. In the normal mode, the thermoelectric effect element is energized. Also, the air passing through the first heat exchanger is introduced to the first outlet port and the air passing through the second heat exchanger is introduced to and discharged from the second outlet port. In the draft mode, the air volume control device is operated to increase a volume of air flowing through the bypass passage so that the ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode.
• Accordingly, the ratio of air introduced to the first outlet port to the air introduced in the inlet port is changed between the draft mode and the normal mode. Namely, in the draft mode, the volume of air blown from the seat surface is larger than that in the normal mode since the volume of air passing through the bypass passage is increased by the operation of the air volume control device. Accordingly, a draft effect on the seat surface improves. On the other hand, in the normal mode, the air blown from the first outlet port has an air conditioning effect through the first heat exchanger. Further, since the air is introduced to the first outlet port through the bypass passage, a pressure loss reduces. With this, the volume of air blown from the first outlet port increases.
BRIEF DESCRIPTION OF THE DRAWINGS
• Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:
• FIG. 1 is a schematic diagram of a seat air conditioning unit according to a first example embodiment of the present invention;
• FIG. 2 is a flow chart for showing a procedure of a control operation of the seat air conditioning unit according to the first example embodiment;
• FIG. 3 is a chart for showing a timing of switching an operation mode between a draft mode and a normal mode and an electric current supply to a Peltier element in the control operation according to the first example embodiment;
• FIG. 4 is a graph for showing a change of a seat temperature with time in a cooling down operation according to the first example embodiment;
• FIG. 5 is a chart for showing a timing of switching the operation mode and an electric conduction state of the Peltier element according to a first modification of the first example embodiment shown inFIG. 3;
• FIG. 6 is a flow chart for showing a procedure of the control operation according to the first modification shown inFIG. 5;
• FIG. 7 is a chart for showing a timing of switching the operation mode and an electric conduction state of the Peltier element according to a second modification of the first example embodiment shown inFIG. 3;
• FIG. 8 is a flow chart for showing a procedure of the control operation according to the second modification shown inFIG. 7;
• FIG. 9 is a flow chart for showing a procedure of the control operation according to a second example embodiment of the present invention;
• FIG. 10 is a flow chart for showing a procedure of the control operation according to a modification of the second example embodiment;
• FIG. 11 is a schematic diagram of a part of the seat air conditioning unit according to a third example embodiment of the present invention;
• FIG. 12 is a schematic diagram of a part of the seat air conditioning unit according to a fourth example embodiment of the present invention;
• FIG. 13 is a schematic diagram of a part of the seat air conditioning unit according to a fifth example embodiment of the present invention;
• FIG. 14 is a schematic diagram of a past of the seat air conditioning unit according to a sixth example embodiment of the present invention;
• FIG. 15 is a schematic diagram of a part of the seat air conditioning unit according to a modification of the fourth example embodiment;
• FIG. 16 is a schematic diagram of a part of the seat air conditioning unit according to another modification of the fourth example embodiment; and
• FIG. 17 is a schematic diagram of a par of the seat air conditioning unit according to further another modification of the fourth example embodiment.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT
• A first example embodiment of the present invention will now be described with reference to FIGS.1 to4. As shown inFIG. 1, a seatair conditioning unit1 of the first example embodiment is for example mounted to aseat bottom21 of aseat20. Alternatively, the seatair conditioning unit1 can be mounted to a seat back22.
• The seatair conditioning unit1 has aduct2, ablower4 and aheat exchanger unit9. Theduct2 forms aninlet port3 at one end (left end inFIG. 1) and theblower unit4 is located upstream of theinlet port3. Theheat exchanger unit9 is located downstream of theblower unit4 in theduct2. Theblower unit4 sucks air and blows the air into theduct2. The seatair conditioning unit1 is for example used in a vehicle. In this case, theblower unit4 sucks air inside a passenger compartment. Theblower unit4 is disposed such that the air is fully introduced into a passage space of theduct2 through theinlet port3. InFIG. 1, an axial flow fan is illustrated as a fan of theblower unit4. Instead, theblower unit4 can have a centrifugal fan.
• The passage space of theduct2 is divided into afirst passage5 and asecond passage6 downstream of theinlet port3. Theduct2 forms afirst outlet13 at a downstream end of thefirst passage5 and asecond outlet14 at a downstream end of thesecond passage6.
• Thefirst outlet13 communicates withseat openings24, so that the air introduced to thefirst outlet13 is blown from a seat surface of theseat20 through theseat openings24. Here, thefirst passage5, thefirst outlet13 and theseat openings24 form a channel through a conditioning air flows. Thesecond outlet14 serves as an opening for discharging a waste heat. The air (waste heat air) passing through thesecond passage6 is discharged to an outside of theseat20 through thesecond outlet14.
• Theheat exchanger unit9 is located between theinlet port3 and the first andsecond outlets13,14 in theduct2. Theheat exchanger unit9 includes aPeltier element8, afirst heat exchanger10 and asecond heat exchanger11. ThePeltier element8 is provided as a thermoelectric effect element, and has afirst side8aand asecond side8b. In a cooling operation, thefirst side8afunctions as a heat absorbing side and thesecond side8bfunctions as a heat radiating side. The heat absorbing side and the heat radiating side of thePeltier element8 are switched according to a flow direction of electric current in thePeltier element8.
• Thefirst heat exchanger10 and thesecond heat exchanger11 are arranged adjacent to thefirst side8aand thesecond side8bof thePeltier element8, respectively, and use heat from thePeltier element8.
• ThePeltier element8 generally has a plate shape and is disposed to partly form aseparation wall7 between thefirst passage5 and thesecond passage6. Thefirst heat exchanger10 is located in thefirst passage5 and thesecond heat exchanger11 is located in thesecond passage6. Namely, the air passing through thefirst heat exchanger10 is fully introduced to thefirst outlet13 through thefirst passage5. Likewise, the air passing through thesecond heat exchanger11 is fully introduced to thesecond outlet14 through thesecond passage6.
• In theduct2, afirst door12 is provided upstream of thesecond heat exchanger11 as a first open and close member. Thefirst door12 is actuated by adoor motor31 through alink32. Thefirst door12 is supported to move between a normal mode position (shown in dashed line inFIG. 1) and a draft mode position (shown in a solid line inFIG. 1). When thefirst door12 is at the normal mode position, thefirst passage5 and thesecond passage6 are fully open. When thefirst door12 is at the draft mode position, thesecond passage6 is fully closed and thefirst passage5 is open.
• In the normal mode, that is, when thefirst door12 is at the normal mode position, the air blown in theinlet port3 is separated into thefirst passage5 and thesecond passage6. The air in thefirst passage5 is cooled through thefirst heat exchanger10 and introduced to thefirst outlet13. The air in thesecond passage6 is heated through thesecond heat exchanger11 and introduced to thesecond outlet14. In the example embodiment shown inFIG. 1, thesecond passage6 is located on thesecond side8bof thePeltier element8. Thus, the heated air is discharged from the second outlet (heat waste opening)14 to the outside of theseat20.
• In a draft mode, that is, when thefirst door12 is at the draft mode position, the air introduced in theinlet port3 is fully introduced into thefirst heat exchanger10 and then introduced to thefirst outlet port13 through thefirst passage5. At this time, the air is restricted from passing through thesecond heat exchanger11 by thefirst door12. Accordingly, in the draft mode, the volume of air introduced in thefirst outlet3 is substantially equal to the volume of air introduced to theinlet port3, i.e., the volume of air produced by theblower unit4. Namely, the volume of air blown from thefirst outlet13 in the draft mode is larger than that in the normal mode, with respect to the same volume of air introduced in theinlet port3.
• Next, an electric control part of the seatair conditioning unit1 will be described. The seatair conditioning unit1 has anECU30 as a control means. TheECU30 is constructed of a microcomputer and peripheral circuits.
• TheECU30 is connected to an insideair temperature sensor33 and aseat temperature sensor34. The insideair temperature sensor33 is for example located adjacent to a suction side of theblower unit4. The insideair temperature sensor33 detects a temperature of the inside air to be introduced into thesuction port3 and outputs a signal Tr of the detected inside air temperature to theECU30.
• Theseat temperature sensor34 detects a temperature of theseat20 and outputs a signal Ts of the detectedseat temperature20 to theECU30. Theseat temperature sensor34 is for example located in acushion member34 of theseat20 to avoid directly receiving an effect of the air blown from theseat openings24 and an effect of theheat exchanging unit9.
• TheECU30 controls theblower unit4 in duty system to produce the necessary volume of air. Also, theECU30 controls thedoor motor31 so that thefirst door12 is operated to the draft mode position and the normal mode position.
• Further, theECU30 controls the electric current supply to thePeltier element8 in duty system so as to control the quantity of heat absorbed to and radiated from thePeltier element8.
• In a Peltier system of the first example embodiment, which is constructed of thePeltier element8, theheat exchanger unit9, theduct2 and theblower unit4, a value ΔPt is 5° C. Here, the value ΔPt is a difference between a temperature of air at an inlet side of thePeltier element8, which corresponds to the inside air temperature Tr, and a temperature of air at an outlet side of thefirst heat exchanger10 when thePeltier element8 and theblower unit4 are operated at a maximum level. Namely, the value ΔPt is a temperature difference created by thefirst heat exchanger10 with respect the inside air temperature Tr, for cooling the seat surface of theseat20.
• Next, operation of the seatair conditioning unit1 will be described.FIG. 2 shows a procedure of a control operation executed by theECU30. The control operation is started when an electric power supply to theECU30 is switched on. For example, the electric power supply to theECU30 is switched at a timing when a power switch (not sown) of the seatair conditioning unit1 is turned on. Alternatively, the electric power supply to theECU30 is switched on according to a timing when a door of a parked vehicle is unlocked. In the latter case, the seatair conditioning unit1 starts the operation in the draft mode before the passenger sits on theseat20, so the temperature of theseat20 is effectively reduced.
• First, as an initial setting, theblower unit4 is set to a shutdown condition and thePeltier element8 is set to off. That is, the electric current to thePeltier element8 is set to zero. Next, at a step S100, it is determined whether the seat temperature Ts is equal to or higher than a threshold value T1 (e.g., 30° C.). When it is determined that the seat temperature Ts is lower than the threshold value T1, the procedure proceeds to a step S160. At the step S160, a normal operation is performed.
• When it is determined that the seat temperature Ts is equal to or higher than the threshold value T1 at the step S100, theblower unit4 is operated at a step S110. At this time, theblower motor4ais operated at a maximum level (e.g., duty ratio=99%) so that thefan4 blows the maximum volume of air.
• Next, at a step S120, it is determined whether the temperature difference between the detected seat temperature Ts and the inside air temperature Tr is equal to or greater than the value ΔPt (5° C.). In the draft mode, a large volume of air is blown from theseat openings24 without operating thePeltier element8. Namely, the cooling efficiency of theseat20 enhances by the larger volume of air in the draft mode, as compared to a mode in which a relatively small volume of air cooled by thePeltier element8 is blown from theseat openings24. Therefore, when the temperature difference is equal to or higher than the value ΔPt, the operation is performed in the draft mode.
• In the draft mode of the first example embodiment, thefirst door12 is operated to the draft mode position in the condition that thePeltier element8 is not energized and theblower unit4 is operated at the maximum level (duty ratio=99%). Thus, thesecond passage6 is closed. Namely, the inlet of thesecond heat exchanger11 is closed, so the volume of air introduced to thesecond passage6 is zero. Accordingly, the volume of air discharged from thesecond outlet port14 is zero.
• In the draft mode, the electric current is not supplied to thePeltier element8. Therefore, even if the volume of air on the heat radiating side, i.e., the volume of air flowing in thesecond heat exchanger11 is zero, it is less likely that thePeltier element8 will be broken. Further, a power consumption reduces.
• According to the operation in the draft mode, the air introduced to theinlet port3 from theblower unit4 almost passes through thefirst heat exchanger10 and thefirst passage5 and then introduced to theseat openings24 through thefirst outlet13, although there is a slight pressure loss. Accordingly, the ratio of air introduced to thefirst port13 to the of air introduced in theinlet port3 is a maximum. That is, the volume of the air blown from theoutlet port13 is at the maximum level, with respect to the maximum volume of air introduced in theinlet port3.
• Accordingly, in the draft mode, the air having the inside air temperature Tr is blown from theseat openings24 at the maximum level. This operation is effective to immediately cool down theheated seat20. For example, in a bright ambience in summer, the seat temperature Ts (e.g., approximately 60° C.) is immediately reduced at least to a first predetermined level P1 (Tr+ΔPt, e.g., 45 to 50° C.).
• This draft mode operation is performed until the temperature difference between the seat temperature Ts and the inside air temperature Tr becomes smaller than the value ΔPt. Namely, at the step S120, when the difference between the seat temperature Ts and the inside air temperature Tr is smaller than the value ΔPt, the procedure proceeds to a step S140 to shift the operation from the draft mode to the normal mode.
• In the normal mode, first, thefirst door12 is operated to the normal mode position from the draft mode position to open thesecond passage6, i.e., the inlet of thesecond heat exchanger11. Thus, the volume of air introduced into thesecond passage6 increases from zero to a predetermined level.
• In this case, both of thefirst passage5 and thesecond passage6 are open. Thus, the air introduced in theinlet port3 is separated into thefirst passage5 and thesecond passage6.
• Then, at a step S150, thePeltier element8 is energized to perform a duty system control of the normal operation. Then, the procedure proceeds to the step S160 to perform the normal operation.
• In the normal operation at the step S160, the normal cooling down operation is performed in conditions similar to control conditions of a general seat air conditioning control using the Peltier element. For example, when the seat temperature Ts is equal to or higher than a comfortable temperature (e.g., 35° C.), thePeltier element8 and theblower unit4 are operated at maximum levels (duty ratio=99%).
• When the seat temperature Ts reduces below the comfortable temperature (35° C.) as a result of the normal cooling down operation, a regular operation is performed to maintain the seat temperature at the comfortable temperature. In the regular operation, thePeltier element8 and theblower unit4 are operated at a half capacity (duty ratio=50%).
• FIG. 3 shows a mode switching and an electric current supply to thePeltier element8 with respect to the seat temperature Ts in the above control operation. As shown inFIG. 3, when the seat temperature Ts is equal to or higher than the threshold value T1, the draft mode is selected and the electric power is not supplied to thePeltier element8. Then, the seat temperature Ts reduces below the first predetermined temperature P1 (Tr+ΔPt), the operation mode is switched to the normal mode and the electric current is supplied to thePeltier element8.
• Next, advantageous effect of the above control operation will be described with reference toFIG. 4.FIG. 4 shows the change of the seat temperature Ts in the cooling down operation with respect to an elapsed time.
• At an initial point, i.e., when the elapsed time is zero, a temperature of outside air is 40° C. under bright sunlight. Also, the inside air temperature Tr is approximately 45° C., and the seat temperature Ts is 60° C. A dotted line A shows a change of the seat temperature Ts when the control operation is performed only in the draft mode (large volume of air, Pelier element off). A dashed line B shows the change of the seat temperature Ts when the control operation is performed only in the normal mode (Peltier element on, thesecond passage6 open). A solid line C shows the change of the seat temperature Ts when the control operation is performed in the manner of the first example embodiment described above.
• Here, a vehicle air conditioner starts its operation from the initial point. Thus, the inside air temperature Tr reduces to 40° C. several minutes (e.g., about 5 minutes) after an operation of the vehicle air conditioner is started. The inside air temperature Tr becomes a setting temperature (25° C., which is set by the vehicle air conditioner, in a regular state.
• In the operation condition A, the inside air having the temperature Tr, which is 15 to 20° C. lower than the seat temperature Ts, is blown at an initial stage. Also, the large volume of air is blown. Thus, the operation condition A provides a cooling effect higher than that of the operation condition B. The passenger on theseat20 is likely to feel airflow and cool.
• As the time elapses, the seat temperature Ts reduces. When the seat temperature Ts approaches the inside temperature Tr, it is difficult to absorb heat of theseat20 in the operation condition A. Thus, the seat temperature Ts reaches a level of saturation due to a body temperature of the passenger in the regular state.
• In the operation condition B, even when the seat temperature Ts approaches the inside temperature Tr with the elapse of time, a high cooling effect is provided. Further, it is possible to cool theseat20 to a temperature (e.g., equal to or lower than 35° C. in summer) that the passenger feels cold. Thus, the seat temperature Ts is effectively controlled by using thePeltier element8.
• Here, in the operation condition B, the electric power is continuously supplied to thePeltier element8 without performing a temperature control. Thus, the line B shows a seat cooling capacity when the electric power is continuously supplied to thePeltier element8.
• As shown in the operation condition C, at an initial stage of the cooling down operation right after the operation of the seatair conditioning unit1 is started, the seat temperature Ts is immediately reduced by the large volume of air in the draft mode. Then, when the seat temperature Ts approaches the inside temperature Tr, the operation mode is switched to the normal mode. Thus, the seat temperature Ts is positively controlled by using thePeltier element8 in the normal mode. Accordingly, this control operation is effective to provide a cool feeling to the passenger.
• The first example embodiment will be modified as follows.FIG. 5 shows a first modification of the first example embodiment. As shown inFIG. 5, when the seat temperature Ts is equal to or higher than a first predetermined temperature P1, the operation is performed in the draft mode in a condition that thePeltier element8 is energized. In the first modification, the first predetermined temperature P1 is Tr+ΔPt+1° C. When the seat temperature Ts reduces below the first predetermined temperature P1 (Tr+ΔPt+1° C.), thePeltier element8 is energized. Then, the seat temperature Ts reduces below a second predetermined temperature P2 (Tr+ΔPt), the operation mode is switched to the normal mode.
• There is a time delay to reduce the temperature of thePeltier element8 so as to have sufficient cooling effect after the electric current supply to thePeltier element8 is started. Therefore, in the first modification, thePeltier element8 is energized before the operation mode is switched from the draft mode to the normal mode. The temperature of air is immediately reduced at the same time as reducing the volume of air. Therefore, even if the volume of air is reduced, the passenger who has been satisfied with the draft feeling can feel cool at that timing.
• The procedure of the control operation of the first modification will be described with reference toFIG. 6. Similar to the procedure shown inFIG. 2, when the seat temperature Ts is equal to or higher than the threshold value T1, theblower unit4 is operated at the maximum level at the step S110.
• Next, at a step S120a, it is determined whether the seat temperature Ts is lower than the first predetermined temperature P1 (Tr+ΔPt+1° C.). When the seat temperature Ts is equal to or higher than the first predetermined temperature P1, the operation is performed in the draft mode at the step S130.
• Then, when the seat temperature Ts reduces below the first predetermined temperature P1, it is determined whether the seat temperature Ts is lower than the second predetermined temperature P2 (Tr+ΔPt) at a step S120b. When the seat temperature Ts is equal to or higher than the second predetermined temperature P2, thePeltier element8 is energized at the step S150. Then, when the seat temperature Ts reduces lower than the second predetermined temperature P2, the operation mode is switched to the normal mode at a step S140. Then, the normal operation is performed at the step S160.
• In the first modification of the first example embodiment, the difference between the first predetermined temperature P1 and the second predetermined temperature P2 is 1° C. This temperature difference can be modified to another fixed value or a variable value calculated based on the inside temperature Tr.
• FIG. 7 shows a second modification of the first example embodiment. As shown inFIG. 7, when the seat temperature Ts is equal to or higher than a first predetermined temperature P1 (Tr+ΔPt), the operation is performed in the draft mode and thePeltier element8 is not energized. When the seat temperature Ts reduces below the first predetermined temperature P1, thePeltier element8 is energized. Then, when a predetermined time Et1 (e.g., 10 seconds) has elapsed since thePeltier element8 was energized, the operation mode is switched to the normal mode. For example, the predetermined time Et1 is set by using a timer.
• Also in the second modification, thePeltier element8 is energized before the operation mode is switched from the draft mode to the normal mode. Accordingly, advantageous effects similar to those of the first modification are provided.
• The control operation of the second modification will be described with reference toFIG. 8. The control operation shown inFIG. 8 is different from the control operation shown inFIG. 6 at steps S120cand S120d. The first predetermined temperature P1, which is the threshold value at the step S120c, is Tr+ΔPt. At the S120d, it is determined whether the predetermined time period Et1 has elapsed. Steps other than the steps S120cand S120dare similar to those of the first modification shown inFIG. 6.
• In the control operations shown inFIGS. 2, 6,8, the threshold value compared to the seat temperature Ts is set by using the inside temperature Tr and ΔPt. However, the threshold value can be changed based on a type of vehicle, a region in use, a user, or a use condition. Further, the threshold value can be a fixed value.
• Next, a second example embodiment of the present invention will be described with reference toFIG. 9. In the second example embodiment, structure of the seatair conditioning unit1 is similar to that of the first example embodiment. Thus, description of like structures will not be repeated. However, the control operation performed by theECU30 is different from that of the first example embodiment. Hereafter, the control operation of the second example embodiment will be described.
• When the electric power supply to theECU30 is switched on, the initial setting is performed in a manner similar to the first example embodiment. Next, at a step S105, it is determined whether the inside temperature Tr detected by the insideair temperature sensor33 is equal to or higher than a threshold value T2 (e.g., 30° C.). The threshold value T2 is can be changed based on a type of vehicle, a region in use, a user, or a use condition.
• When the inside temperature Tr is lower than the threshold value T2, the procedure proceeds to step S160, so the normal operation is performed, similar to the first example embodiment.
• When the inside temperature Tr is equal to or higher than the threshold value T2 at the step S105, theblower unit4 is operated at the maximum level (duty ratio=99%) at the step S110, similar to the first example embodiment. Next, at a step S115, it is determined whether a predetermined time period Et2 (e.g., 2 minutes) has elapsed. The predetermined time period Et2 is previously set by the timer. The predetermined time period Et2 is changed based on various conditions such as an assumed use condition or a type of vehicle.
• When it is determined that the predetermined time period Et2 has not elapsed at the step S115, the operation is performed in the draft mode at the step S130. In the draft mode, thePeltier element8 is not energized, and theblower unit4 is operated at the maximum level (duty ratio=99%), similar to the draft mode of the first example embodiment. In this condition, thefirst door12 is operated to the draft mode position to close the inlet of thesecond heat exchanger11. Thus, the volume of air discharged from thesecond outlet port14 is zero.
• According to the operation in the draft mode, since thesecond passage6 is closed with thefirst door12 in a condition that the electric current is not supplied to thePeltier element8, the air introduced in theinlet port3 almost introduced to thefirst outlet port13 and blown from theseat openings24. Thus, the large volume of air is blown from theseat openings24. Accordingly, the seat temperature Ts is immediately reduced close to the inside air temperature Tr by the draft effect.
• When the predetermined time Et2 has elapsed since the operation in the draft mode was started, that is, it is determined YES at the step S115, the operation mode is switched to the normal mode at the step S140. First, thefirst door12 is operated to the normal mode position at which thesecond passage6 is opened, i.e., the inlet of thesecond heat exchanger11 is open. Thus, the volume of air introduced into thesecond passage6 increases to the predetermined level from zero.
• In this case, thefirst passage5 and thesecond passage6 are open. Thus, the air introduced in theinlet port3 separates into thefirst passage5 and thesecond passage6. Then, similar to the first example embodiment, at the step S150, thePeltier element8 is energized to perform the normal operation in duty system control. Then, the normal operation is performed at the step S160.
• In the normal operation in the step S160, the normal cooling down operation is performed in conditions similar to control conditions of the general seat air conditioning control using the Peltier element. For example, when the seat temperature Ts is equal to or higher than the comfortable temperature (e.g., 35° C.), thePeltier element8 and theblower unit4 are operated at the maximum level (duty ratio=99%).
• When the seat temperature Ts reduces below the comfortable temperature (35° C.) as a result of the normal cooling down operation, the regular operation is performed to maintain the seat temperature at the comfortable temperature. In the regular operation, thePeltier element8 and theblower unit4 are operated at a half capacity (duty ratio=50%).
• Accordingly, the control operation of the second example embodiment provides advantageous effects similar to those of the first example embodiment.
• In the second example embodiment shown inFIG. 9, the timing of switching the operation mode from the draft mode to the normal mode is determined based on the elapsed time Et2 at the step S115. However, the control operation of the second example embodiment will be modified as shown inFIG. 10. InFIG. 10, a step S125 for determining whether the inside temperature Tr is equal to or lower than a predetermined temperature T3 that is lower than the threshold value T2 is provided in place of the step S115 ofFIG. 9. Accordingly, when the inside temperature Tr is equal to or lower than the predetermined temperature T3 that is lower than the threshold value T2, the draft mode operation is terminated and switched to the normal mode.
• A third example embodiment will be described with reference toFIG. 11. As shown inFIG. 11, asecond door15 is provided as the first open and close member, in place of thefirst door12 of the first and second example embodiments. Structures other than thesecond door15 are similar to those of the first and second example embodiments. InFIG. 11, only the part from theinlet port3 to the first andsecond outlet ports13,14 is illustrated. Further, like components are denoted by like reference characters and a description thereof is not repeated.
• Thesecond door15 is located downstream of theheat exchanger unit9. Further, thesecond door15 is supported to open and close thesecond passage6 at a position downstream of thesecond heat exchanger11. When thesecond door15 is at a position to close thesecond passage6, an opening15aformed on theseparation wall7 between thefirst passage6 and thesecond passage7 is open. Thus, the air passing through thesecond heat exchanger11 flows into thefirst passage5 through the opening15a. When thesecond door15 is at a position to close the opening15a, thesecond passage6 is fully open. Thus, the air passing through thesecond heat exchanger11 is restricted from flowing into thefirst passage5. Thesecond door15 is rotated by thedoor motor31 through alink32a, similar to thefirst door12 of the first and second example embodiments.
• In the third example embodiment, theECU30 performs the control operation in a manner similar to the first and second example embodiments shown inFIGS. 2, 6,8,9 and10, except the operation of thesecond door15. Thesecond door15 is operated in the following manner.
• In the normal mode in which thePeltier element8 is energized to have the cooling effect by thefirst heat exchanger10 to have cooling effect, thesecond door15 is operated to a normal mode position shown by dotted line inFIG. 11. Namely, the opening15ais fully closed and thesecond passage6 is open so that the air that receives heat from thePeltier element8 through thesecond heat exchanger11 is discharged from thesecond outlet port14 as the waste heat.
• Since thesecond door15 is positioned to close the opening15aand open thesecond passage6 in the normal mode, the air is distributed in the manner similar to that in the normal mode of the first and second example embodiments.
• In the draft mode, that is, at the step S130 ofFIGS. 2, 6,8,9, and10, thesecond door15 is operated to a draft mode position shown by a solid line inFIG. 11. Namely, thesecond door15 fully closes thesecond passage6 and opens the opening15a. After the termination of the draft mode, that is, at the step S140 ofFIGS. 2, 6,8,9 and10, thesecond door15 is operated to the normal mode position shown by the dotted line inFIG. 11.
• Accordingly, in the draft mode, the air passing through thesecond heat exchanger11 flows into thefirst passage5 through the opening15a. Since both the air passing through thefirst heat exchanger10 and the air passing through thesecond heat exchanger11 are introduced to thefirst outlet port13, the ratio of the air introduced to thefirst outlet port13 to the air introduced to theinlet port3 increases.
• In the draft mode, thePeltier element8 is not energized. Therefore, the air passing through thesecond heat exchanger11 does not receive heat from thePeltier element8 and has the temperature similar to the temperature of the inside air.
• Also in the third example embodiment, advantageous effects similar to those of the first and second example embodiments are provided.
• Next, a fourth example embodiment will be described with reference toFIG. 12. As shown inFIG. 12, theduct2 has abypass passage16 and athird door17 as a second open and close member, in place of thefirst door12 of the first open and close member. Other structures are similar to those of the first and second example embodiments. InFIG. 12, only the part from theinlet port3 to the first andsecond outlet ports13,14 is illustrated. Further, like components are denoted by like reference characters and a description thereof is not repeated.
• Thebypass passage16 is disposed to allow the air to bypass thefirst heat exchanger10. For example, thebypass passage16 is located on the opposite side as thesecond heat exchanger11, with respect to thefirst heat exchanger10, in thefirst passage5. Thethird door17 is located adjacent to an inlet of thebypass passage16 to open and close thebypass passage16. Thethird door17 is operated by thedoor motor31 through alink32b, similar to thefirst door12 of the first and second example embodiments.
• In the fourth example embodiment, theECU30 performs the control operation, in a manner similar to the first and second example embodiment, except the operation of thethird door17. Thethird door17 is operated in the following manner, in place of thefirst door12.
• First, in the normal mode in which thePeltier element8 is energized to have the cooling effect by thefirst heat exchanger10, thethird door17 is operated to a normal mode position shown by dotted line inFIG. 12. Namely, the third door closes thebypass passage16. Thus, approximately half of the air introduced in theinlet port3 is cooled through thefirst heat exchanger10. The cooled air passes through thefirst outlet port13 and is blown from theseat openings24.
• The remaining half of the air is heated through thesecond heat exchanger11 according to the operation of thePeltier element8. The heated air is discharged from thesecond outlet port14 to the outside of theseat20. Since thethird door17 closes thebypass passage16 in the normal mode, the air is distributed in a manner similar to that in the normal mode of the first to third example embodiments.
• In the draft mode, that is, at the step S130 ofFIGS. 2, 6,8,9, and10, thethird door17 is operated to a draft mode position shown by solid line inFIG. 12. Namely, thethird door17 is positioned to fully open thebypass passage16. After the termination of the draft mode, that is, at the Step S140 ofFIGS. 2, 6,8,9, and10, thethird door17 is operated to the normal mode position shown by the dotted line inFIG. 12.
• Accordingly, the pressure loss in thefirst passage5 reduces in the draft mode. Therefore, the volume of air introduced to thefirst outlet port13 through thefirst passage5 increases. Namely, the ratio of the air blown from thefirst outlet port13 to the air introduced in theinlet port3 increases, as compared to a case without having thebypass passage16.
• Also in the fourth example embodiment, advantageous effects similar to those of the first and second example embodiments are provided.
• Similar to the above example embodiments, thePeltier element8 is not energized in the draft mode. Therefore, power consumption reduces. However, since the inlet of thesecond heat exchanger11 is always open and the air passing through thesecond heat exchanger11 is always discharged from thesecond outlet port14 to the outside of theseat20, it is not always necessary to stop the electric current supply to thePeltier element8.
• Therefore, in the draft mode of the steps S110 inFIGS. 2, 6,8,9, and10, the electric current can be supplied to thePeltier element8. Thus, the air can be cooled through thefirst heat exchanger10 and the cooled is blown from thefirst outlet port13 in the draft mode.
• In this case, the cooling effect in the draft mode is lower than that in the normal mode, because the volume of air in thebypass passage16 increases. However, since the volume of air blown from theseat openings24 increases, the draft effect improves. Thus, the seat temperature Ts is further reduced by the cooled air having the temperature lower than the inside temperature Tr.
• Further, the volume of the air blown from thefirst outlet13 is increased since the pressure loss in thefirst passage5 is reduced. Therefore, a power required to theblower unit4 reduces. Furthermore, noise effect reduces.
• Next, a fifth example embodiment will be described with reference toFIG. 13. As shown inFIG. 13, theduct2 has thesecond door15 as the first open and close member, which is similar to thesecond door15 of the third example embodiment, in place of thefirst door12. Also, theduct2 has thethird door17 as the second open and close member, which is similar to thethird door17 of the fourth example embodiment. Further, theduct2 has thebypass passage16. Other structures are similar to the first and second example embodiments. InFIG. 13, only the part from theinlet port3 to the first andsecond outlet ports13,14 is illustrated. Further, like components are denoted by like reference characters and a description thereof is not repeated.
• Similar to the third example embodiment, thesecond door15 as the first open and close member is located downstream of thesecond heat exchanger11 in thesecond passage6. Thesecond door15 is operated to open and close thesecond passage6 and theopening15aformed in theseparation wall7. Similar to the fourth example embodiment, thebypass passage16 is formed in thefirst passage5 to allow the air to bypass thefirst heat exchanger10. Also, thethird door17 as the second open and close member is located at the inlet of thebypass passage16 to open and close thebypass passage16. Thesecond door15 and thethird door17 are simultaneously operated by thedoor motor31 through thelinks32a,32b.
• Also in the fifth example embodiment, theECU30 performs the control operation in a manner similar to that of the first and second example embodiments, except the operation of thesecond door15 and thethird door17. Thesecond door15 and thethird door17 are operated in the following manner.
• First, in the normal mode in which thePeltier element8 is energized to have the cooling effect by thefirst heat exchanger10, thesecond door15 is at the normal mode position shown by dotted line inFIG. 13. Also, thethird door17 is at a position shown by dotted line inFIG. 13. Namely, thesecond door15 fully closes the opening15aand fully opens thesecond passage6 so that the air passing through thesecond heat exchanger11 is discharged from thesecond outlet port14 to the outside of theseat20. Thethird door17 closes thebypass passage16. Thus, approximately half of the air introduced in theinlet port3 is introduced to thefirst heat exchanger10 and cooled. The cooled air is blown from theseat openings24 through thefirst outlet port13.
• In the draft mode, that is, at the step S130 ofFIGS. 2, 6,8,9, and10, thesecond door15 is operated to the position shown by solid line inFIG. 13. Also, thethird door17 is operated to the position shown by solid line inFIG. 13. Namely, thesecond door15 fully closes thesecond passage6 and fully opens the opening15a. Thethird door17 fully opens thebypass passage16.
• After the termination of the draft mode, that is, at the step S140 ofFIGS. 2, 6,8,9, and10, thesecond door15 is operated to the position shown by solid line inFIG. 13. Also, thethird door17 is operated to the position shown by dotted line inFIG. 13.
• Accordingly, in the draft mode, the air passing through thefirst passage5 and the air passing through thesecond heat exchanger11 are introduced to thefirst outlet port13. Therefore, the ratio of the air introduced to thefirst outlet port13 to the air introduced in theinlet port3 increases, as compared to that in the normal mode.
• Further, the pressure loss in thefirst passage5 reduces since thebypass passage16 is open in the draft mode. Therefore, the volume of air passing through thefirst passage5 increases. Furthermore, since the air passing through thesecond heat exchanger11 is introduced to thefirst passage5 through the opening15a, the volume of air blown from thefirst outlet port13 is increased larger than that of the first to fourth example embodiments. In the draft mode, since thePeltier element8 is not energized, the air passing through thesecond heat exchanger11 does not receive heat from thePeltier element8 and has the temperature similar to that of the inside air.
• Also in the fifth example embodiment, advantageous effects similar to those of the first and second embodiments are provided.
• The above example embodiments will be further modified in the following manner.
• In the above example embodiments shown inFIGS. 11 and 12, theheat exchanger unit9 are configured such that the air flows parallel to thePeltier element8. Alternatively, awall10aof thefirst heat exchanger10, which faces thebypass passage16, can be formed with openings, as shown inFIG. 14.
• For example, in the Peltier module including thePeltier element8 and the first andsecond heat exchangers10,11,fins10b,11bare generally provided along thesurfaces8a,8bof thePeltier element8 for performing heat exchange. Thefins10b,11bare sandwiched bywalls10a,11. Here, theopenings10care formed on thewall10a. Instead of forming theopenings10con thewall10a, thewall10acan be removed.
• Accordingly, the air passing through thefirst heat exchanger10 can flow upwardly toward thebypass passage16. Therefore, the pressure loss of the air passing through thefirst heat exchanger10 further reduces. In the example embodiment shown inFIG. 14, theopenings10care exemplary employed in the structure shown inFIG. 12. Theopenings10ccan be employed in the structure shown inFIG. 13.
• As a modification of the fourth example embodiment shown inFIG. 12, thefirst door12 as the first open and close member can be arranged upstream of thesecond heat exchanger11, as shown inFIG. 15. Thefirst door12 is operated by thedoor motor31 through thelink32, similar to the first and second example embodiments. In this case, theECU30 performs the control operation in a manner similar to the first and second example embodiments. Here, thefirst door12 is operated in the manner similar to those of the first and second example embodiments. Thethird door17 is operated in the manner similar to that of the fourth example embodiment. In this case, thePeltier element8 is not energized in the draft mode.
• In the example embodiment shown inFIG. 12, thethird door17 is arranged at the upstream position of thebypass passage16. Alternatively, thethird door17 can be arranged at a position downstream of thefirst heat exchanger10, as shown inFIG. 16. Alternatively, thethird door17 can be arranged at a substantially midstream position of thebypass passage16, as shown inFIG. 17. Also in the example embodiments shown inFIGS. 13 and 15, the position of thethird door17 can be arranged as shown inFIGS. 16 and 17.
• Further, thebypass passage16 can be formed in a different configuration as long as it allows the air to bypass thefirst heat exchanger10. For example, thebypass passage16 can be formed on a side of thesecond passage6 so that the air bypasses thesecond heat exchanger11. In this case, the air is introduced to thefirst outlet port13 from the bypass passage through a duct.
• In the above example embodiments, thePeltier element8 is not energized, that is, the electric current to thePeltier element8 is zero in the draft mode. Instead, thePeltier element8 can be operated at a small duty ratio in the draft mode as long as the rate of heat exchange in the first andsecond heat exchangers10,11 in the draft mode is smaller than that in the normal mode.
• In the first example embodiment, the seat temperature Ts detected by theseat temperature sensor34 is used as a physical value relating to the temperature of the seat surface. In the second example embodiment, the inside temperature Tr detected by the insideair temperature sensor33 is used as the physical value relating to the temperature of the seat surface. However, the temperature of the seat surface can be obtained in a different way.
• For example, the temperature of the seat surface can be estimated by correcting the inside temperature Tr with one of the quantity of solar radiation, the outside temperature, a temperature of heat exchange that is detected by a sensor provided downstream of theheat exchanger unit9. Alternatively, the temperature of the seat surface can be estimated based on the outside temperature, the quantity of solar radiation, and a cumulative time thereof. Further, the temperature of the seat surface can be estimated based on the quantity of solar radiation, the outside temperature, and the temperature of heat exchange.
• In the above example embodiments, the first, second andthird doors12,15,17 are operated by thedoor motor31 through thelinks32,32a,32b. However, the structure of thedoors12,15,17 are not limited to the illustrated example embodiments. For example, thesecond door15 of the third and fifth example embodiments can be formed of a material that is deformable according to an ambient temperature, e.g., bimetal or shape memory alloy.
• In such a case, when the temperature of air passing through thefirst heat exchanger10 reduces in a condition that thePeltier element8 is energized, thesecond door15 opens thesecond passage6 so that the air is discharged. When the ambient temperature is relatively high in a condition that thePeltier element8 is not energized, thesecond door15 closes thesecond passage6. Therefore, power used to operate thesecond door15 reduces.
• In the above example embodiments, it is mainly described about the cooling down operation for immediately cooling the temperature of the seat surface, for example when the seat temperature Ts is very high in summer. The above described example embodiments can be used to perform warming up operation for heating the seat surface. In this case, the electric current is supplied to thePeltier element8 in an opposite direction. Thus, the heat absorbing side and the heat radiating side of theheat exchanger unit9 are reversed.
• For example, when the temperature of the seat surface is low in winter, thefirst door12 inFIG. 1 is operated to close the inlet of thesecond heat exchanger11 so that the volume of air blown from thefirst outlet port13 increases. In this case, thePeltier element8 is not energized. Thus, the air blown from thefirst outlet port13 by the operation of theblower unit4 has a temperature higher than the temperature of the cold seat surface. Accordingly, the seat surface is warmed.
• Further, when the temperature of the seat surface approaches the inside temperature, the operation mode is switched from the draft mode to the normal mode. The electric current is supplied to thePeltire element8 so that thePeltier element8 has the heat radiating surface on the side of thefirst heat exchanger10 and the heat absorbing surface on the side of thesecond heat exchanger11. Also, thefirst door12 is operated to open the inlet of thesecond heat exchanger11. Thus, the air heated through thefirst heat exchanger10 is introduced to thefirst outlet port13 through thefirst passage5 and is blown from theseat openings24. The air cooled through thesecond heat exchanger11 is introduced to thesecond outlet port14 through thesecond passage6 and is discharged to the outside of theseat20.
• In the above example embodiments, theblower unit4 is operated at the maximum level in the draft mode. Here, the maximum level is determined within a maximum level in an actual use condition satisfying the quality in view of the performance and reducing vibration and noise.
• The example embodiments of the present invention are described above. However, the present invention is not limited to the above example embodiments, but may be implemented in other ways without departing from the spirit of the invention.

Claims (25)

1. An air conditioning unit for a seat for blowing air from a seat surface, comprising:

a duct defining an inlet port and a passage space through which air introduced in the inlet port flows, the passage space separating into a first passage and a second passage, the first passage defining a first outlet port through which air is blown to the seat surface, and the second passage defining a second outlet port through which air is discharged;

a heat exchanger unit disposed between the inlet port and the first and second outlet ports in the duct, the heat exchanger unit having a thermoelectric effect element, a first heat exchanger, and a second heat exchanger, the thermoelectric effect element including a first side and a second side, one of the first side and the second side radiating heat and the other one of the first side and the second side absorbing heat according to a flow direction of an electric current therein, the first heat exchanger disposed adjacent to the first side for performing heat exchange with air flowing in the first passage, and a second heat exchanger disposed adjacent to the second side for performing heat exchange with air flowing in the second passage; and

an air volume control device disposed in the duct for changing a ratio of air introduced to the first outlet port to the air introduced in the inlet port between a normal mode and a draft mode, wherein

in the normal mode the thermoelectric effect element is energized and the air volume control device is operated such that air passing through the first heat exchanger is introduced to the first outlet port and air passing through the second heat exchanger is introduced to and discharged from the second outlet port, and

in the draft mode the air volume control device is operated so that the ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode, wherein

in a predetermined condition, the air volume control device is operated in the draft mode and an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate in the first and second heat exchangers is smaller than that in the normal mode.

2. The air conditioning unit according toclaim 1, further comprising:

a blower unit disposed upstream of the inlet port of the duct for producing a flow of air into the inlet port.

3. The air conditioning unit according toclaim 2, wherein in the draft mode, the blower unit is operated at a maximum level.

4. The air conditioning unit according toclaim 1, wherein the predetermined condition is satisfied when a physical value relating to a temperature of the seat surface is equal to or higher than a first predetermined value.

5. The air conditioning unit according toclaim 4, wherein

when the physical value is lower than the first predetermined value, the thermoelectric effect element is energized in a condition same as the normal mode, and

when the physical value is lower than a second predetermined value that is lower than the first predetermined value, the air volume control device is operated in the normal mode.

6. The air conditioning unit according toclaim 4, wherein

when the physical value is lower than the first predetermined value, the thermoelectric effect element is energized in a condition same as the normal mode, and

when a first predetermined time period has elapsed since the thermoelectric effect element was energized in the condition same as the normal mode, the air volume control device is operated in the normal mode.

7. The air conditioning unit according toclaim 4, wherein

when the physical value is lower than the first predetermined value, the air volume control device is operated in the normal mode, and the thermoelectric effect element is energized in a condition same as the normal mode.

8. The air conditioning unit according toclaim 4, wherein

when the physical value reduces below a third predetermined value that is lower than the first predetermined value in a condition that the air volume control device is operated in the draft mode and the electric current supply to the thermoelectric effect element is controlled such that the heat exchange rate is smaller than that of the normal mode, the air volume control device is operated in the normal mode and the thermoelectric effect element is energized in a condition same as the normal mode.

9. The air conditioning unit according toclaim 4, wherein

when a second predetermined time period has elapsed since the air volume control device was operated in the draft mode and the electric current supply to the thermoelectric effect element was controlled such that the heat exchange rate is smaller than that of the normal mode in a condition that the physical value is equal to or higher than the first predetermined value, the air volume control device is operated to the normal mode and the thermoelectric effect element is energized in a condition same as that in the normal mode.

10. The air conditioning unit according toclaim 1, wherein

the air volume control device includes a first open and close member, the first open and close member is disposed at a position upstream of the second heat exchanger to open and close the second passage to thereby control a volume of air introduced to the second outlet port, and

in the draft mode the first open and close member is operated to fully close the second passage to restrict the air from flowing to the second outlet port, to thereby increase a volume of air introduced to the first outlet port.

11. The air conditioning unit according toclaim 1, wherein

the air volume control device includes a first open and close member, the first open and close member is disposed to open and close the second passage at a position downstream of the second heat exchanger, when the first open and close member fully closes the second passage the air passing through the second heat exchanger is allowed to flow in the first passage, and when the first open and close member opens the second passage the air passing through the second heat exchanger is restricted from flowing in the first passage, and

in the draft mode the first open and close member is disposed to fully close the second passage to increase a volume of air introduced to the first outlet port.

12. The air conditioning unit according toclaim 11, wherein the first open and close member is formed of a material that deforms according to an ambient temperature and the second passage is open and closed according to deformation of the first open and close member.

13. The air conditioning unit according toclaim 1, wherein

the duct further defines a bypass passage through which air flows toward the first outlet port while bypassing the first heat exchanger and the second heat exchanger,

the air volume control device includes a second open and close member disposed to open and close the bypass passage, and

in the draft mode the second open and close member is operated to open the bypass passage so that a volume of air introduced to the first outlet port increases.

14. The air conditioning unit according toclaim 13, wherein

the second open and close member is disposed at a position upstream of the bypass passage.

15. The air conditioning unit according toclaim 13, wherein the first heat exchanger defines an opening that opens to the bypass passage.

16. An air conditioning unit for a seat for blowing air from a seat surface, comprising:

a duct defining an inlet port and a passage space through which air introduced in the inlet port flows, the passage space separating into a first passage and a second passage, the first passage defining a first outlet port through which air is blown to the seat surface, the second passage defining a second outlet port through which air is discharged, the duct further defining a bypass passage that diverges from the passage space and communicates with the first outlet port of the first passage;

a heat exchanger unit disposed between the inlet port and the first and second outlet ports in the duct, the heat exchanger unit having a thermoelectric effect element, a first heat exchanger, and a second heat exchanger, the thermoelectric effect element having a first side and a second side, one of the first side and the second side radiating heat and the other one of the first side and the second side absorbing heat according to a flow direction of an electric current in the thermoelectric effect element, the first heat exchanger disposed adjacent to the first side for performing heat exchange with air passing through the first passage, the second heat exchanger disposed adjacent to the second side for performing heat exchange with air passing through the second passage; and

an air volume control device disposed in the duct for changing a volume of air flowing in the bypass passage between a normal mode and a draft mode, wherein

in the normal mode the thermoelectric effect element is energized and air passing through the first heat exchanger is introduced to the first outlet port and air passing through the second heat exchanger is discharged from the second outlet port, and

in the draft mode a ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode, wherein

in the draft mode the air volume control device is operated so that a volume of air flowing through the bypass passage toward the first outlet port is larger than that in the normal mode.

17. The air conditioning unit according toclaim 16, further comprising:

a blower unit disposed at a position upstream of the inlet port of the duct for producing a flow of air into the inlet port.

18. The air conditioning unit according toclaim 16, wherein the bypass passage is located between the seat and the first heat exchanger, in the first passage.

19. The air conditioning unit according toclaim 16, wherein in the draft mode an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate of the first and second heat exchangers is smaller than that in the normal mode.

20. The air conditioning unit according toclaim 16, further comprising:

a first open and close member disposed upstream of the second heat exchanger, wherein

the first open and close member is operated to open and close the second passage for controlling a volume of air introduced to the second outlet port, and

in the draft mode the first open and close member is operated to fully close the second passage.

21. The air conditioning unit according toclaim 16, further comprising:

a first open and close member disposed downstream of the second heat exchanger to open and close the second passage, wherein

when the first open and close member fully closes the second passage the air passing through the second heat exchanger is allowed to flow in the first passage and is restricted from flowing to the second outlet port,

when the first open and close member opens the second passage the air passing through the second heat exchanger is restricted from flowing in the first passage, and

in the draft mode the first open and close member is disposed to fully close the second passage.

22. The air conditioning unit according toclaim 21, wherein the first open and close member is formed of a material that deforms according to an ambient temperature, and the second passage is open and closed according to deformation of the first open and close member.

23. The air conditioning unit according toclaim 16, wherein the air volume control device includes a second open and close member disposed to open and close the bypass passage, and in the draft mode, the second open and close member is operated to open the bypass passage so that a volume of air introduced to the first outlet port increases.

24. The air conditioning unit according toclaim 23, wherein the second open and close member is disposed upstream of the bypass passage.

25. The air conditioning unit according toclaim 16, wherein the first heat exchanger forms an opening that opens to the bypass passage.

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