US20080115539A1 - Laundry apparatus - Google Patents

Abstract

A laundry apparatus according to the present invention is capable of stably regulating a laundry drying temperature without reduction in the service life of a valve which regulates the amount of steam to be supplied to heating unit. In the laundry apparatus, a first steam supply passage (24a) having a relatively great passage diameter and a second steam supply passage (24b) having a relatively small passage diameter are provided independently of each other. Thus, a relatively great amount of steam is supplied from the first steam supply passage (24a) to a drying heater (13) with a first valve (V27) being opened, and a relatively small amount of steam is supplied to the drying heater (13) with a second valve (V28) being opened. By selectively using the first valve (V27) and the second valve (V28), the opening/closing frequencies of these valves are reduced. This makes it possible to stably regulate the laundry drying temperature while preventing reduction in the service lives of these valves.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a laundry apparatus having a laundry drying function.
• 2. Description of Related Art
• There are conventionally known laundry apparatuses which are capable of drying laundry contained in a rotatable drum thereof (see, for example, Japanese Unexamined Patent Publication No. HEI8(1996)-168595). Such laundry apparatuses have been introduced in coin-operated laundry shops, cleaning facilities, general households and the like.
• A dry cleaner disclosed in the patent publication described above includes an outer tub and a drum rotatably supported in the outer tub and configured to contain laundry. A circulation duct is connected to the outer tub, and a heater serving as heating unit employing steam as a heat source is provided in the circulation duct. While the laundry contained in the drum is agitated by rotation of the drum, air heated by the heater in the circulation duct is applied to the laundry to dry the laundry.
• In the dry cleaner disclosed in the aforementioned patent publication, a single valve is provided in a steam supply passage which connects a steam source to the heater. With the valve being opened, the steam is supplied from the steam source to the heater. By closing the valve, the supply of the steam to the heater is stopped. Where the temperature of the air heated by the heater is to be changed, a steam supply amount is controlled by opening and closing the valve. If the air heating temperature is changed, a laundry drying temperature (more specifically, the temperature of the air heat-exchanged with the laundry, which is an index indicating the drying state of the laundry) is also changed.
• Where the laundry drying temperature is to be finely controlled, the valve should be frequently opened and closed. This may reduce the service life of the valve. Further, where the amount of the steam to be supplied with the valve being opened is set at a higher level for increasing the laundry drying temperature in a short time, the steam is abruptly supplied to the heater at a higher pressure when the valve is suddenly opened. The impact of the abrupt supply of the steam may damage the heater. If the amount of the supplied steam is increased, the laundry drying temperature is steeply increased. Therefore, where the fine control of the laundry drying temperature is desired, the valve opening/closing frequency is further increased.
SUMMARY OF THE INVENTION
• In view of the foregoing, it is a main object of the present invention to provide a laundry apparatus which is capable of stably regulating a laundry drying temperature without reduction in the service life of a valve which regulates the amount of steam to be supplied to heating unit.
• It is another object of the present invention to provide a laundry apparatus which ensures an extended service life of heating unit.
• A laundry apparatus according to the present invention comprises: a laundry containing tub having an inlet and configured to contain laundry; an air flow passage connected to the inlet of the laundry containing tub to allow air to flow into the laundry containing tub from the inlet; heating unit which heats the air in the air flow passage by steam; a first steam supply passage having a greater passage diameter for supplying the steam to the heating unit; a second steam supply passage provided separately from the first steam supply passage and having a smaller passage diameter for supplying the steam to the heating unit; a first supply valve provided in the first steam supply passage to be opened and closed for permitting and preventing the supply of the steam to the heating unit; and a second supply valve provided in the second steam supply passage to be opened and closed for permitting and preventing the supply of the steam to the heating unit.
• The laundry containing tub may have an outlet, and the air flow passage may include a circulation duct connected to the outlet of the laundry containing tub and configured to allow the air flowing into the laundry containing tub through the inlet to flow out through the outlet to circulate the air in the laundry containing tub.
• The laundry apparatus may further comprise controller which opens and closes the first supply valve and the second supply valve individually or simultaneously. The controller may be configured to first open the second supply valve and then the first supply valve when the heating of the air is started.
• The laundry apparatus preferably further comprises a temperature sensor for detecting an air temperature at the outlet. The controller is preferably configured to close the first supply valve when the temperature detected by the temperature sensor exceeds a target temperature, close the second supply valve when the temperature detected by the temperature sensor is further increased to an upper limit temperature which is higher by a predetermined degree than the target temperature, and open only the second supply valve when the temperature detected by the temperature sensor is reduced to a lower limit temperature which is lower by a predetermined degree than the target temperature.
• According to the present invention, the air is heated in the air flow passage with the steam by the heating unit, and the heated air flows into the laundry containing tub through the inlet to dry the laundry in the laundry containing tub. The first steam supply passage having a relatively great passage diameter and the second steam supply passage having a relative small passage diameter are provided independently of each other for supplying the steam to the heating unit. The first supply valve is provided in the first steam supply passage, and a relatively great amount of steam is supplied to the heating unit from the first steam supply passage with the first supply valve being opened. On the other hand, the second supply valve is provided in the second steam supply passage, and a relatively small amount of steam is supplied to the heating unit with the second supply valve being opened.
• Therefore, the laundry drying temperature can be increased to the target temperature in a short time by mainly opening the first supply valve. After the laundry drying temperature reaches the target temperature, a drastic fluctuation in laundry drying temperature can be suppressed by mainly opening and closing the second supply valve.
• In the present invention, the first supply valve and the second supply valve are selectively used for regulating the laundry drying temperature. Thus, the first supply valve and the second supply valve are less frequently opened and closed as compare with a case where a single supply valve is employed for regulating the laundry drying temperature. This makes it possible to stably regulate the laundry drying temperature, while preventing the reduction in the service lives of the first supply valve and the second supply valve.
• Since the laundry drying temperature is regulated by controlling the valve opening/closing frequencies of the first supply valve and the second supply valve, cost reduction and structural simplification can be achieved without the need for employing an expensive and complicated supply valve capable of controlling the opening degree of the valve.
• The air in the laundry containing tub is circulated through the circulation duct of the air flow passage. Therefore, the air heated by the heating unit and supplied to the laundry containing tub exchanges heat with the laundry in the laundry containing tub to cause moisture contained in the laundry to evaporate, and then is reused for the drying of the laundry rather than being discharged together with the evaporated moisture to the outside. Therefore, the laundry apparatus is environmentally friendly.
• According to the present invention, the controller first opens the second supply valve and then the first supply valve when starting the heating of the air. Therefore, a relatively small amount of steam is first supplied to the heating unit, and then a relatively great amount of steam is supplied to the heating unit. Thus, the pressure of the steam in the heating unit is increased stepwise. If the opening of the first supply valve preceded the opening of the second supply valve, a steam pressure in the heating unit would be steeply increased, so that the impact of the steep pressure increase would result in damage to the heating unit. In the present invention, however, the steam pressure in the heating unit is increased stepwise when the heating of the air is started. Therefore, the impact to be exerted on the heating unit by the steam pressure is alleviated, so that the service life of the heating unit is extended.
• According to the present invention, the temperature sensor detects the laundry drying temperature defined by the air temperature at the outlet, i.e., the temperature of the air heat-exchanged with the laundry in the laundry containing tub. Thus, a laundry drying state can be accurately detected.
• Further, the controller closes the first supply valve when the temperature detected by the temperature sensor exceeds the target temperature, closes the second supply valve when the temperature detected by the temperature sensor is further increased to the upper limit temperature which is higher by a predetermined degree than the target temperature, and opens only the second supply valve when the temperature detected by the temperature sensor is reduced to the lower limit temperature which is lower by a predetermined degree than the target temperature. That is, if the laundry drying temperature is changed from the target temperature, the opening/closing operation of the second supply valve is not performed immediately after the change in laundry drying temperature but after a lapse of a predetermined period for regulating the laundry drying temperature. This prevents the second supply valve from chattering. Since only the second supply valve having a relatively low steam supply capacity is opened and closed for regulating the drying temperature, a drastic fluctuation in drying temperature is suppressed as compared with a case in which the first supply valve having a relatively high steam supply capacity is opened and closed. Therefore, the drying temperature can be stably regulated.
• With reference to the attached drawings, embodiments of the present invention will hereinafter be described more specifically.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a front perspective view of major portions of adry cleaner1 as a laundry apparatus according to one embodiment of the present invention.
• FIG. 2 is a pipeline diagram of the dry cleanerFIG. 3 is a block diagram showing an arrangement for a control operation for the supply of steam to adrying heater13 in thedry cleaner1.
• FIG. 4 is a flow chart for explaining the control operation for the steam supply to thedrying heater13 in a drying process.
• FIG. 5 is a diagram illustrating changes in drum outlet temperature observed with time in the drying process with and without the inventive arrangement.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTSExternal Construction of Dry Cleaner
• FIG. 1 is a front perspective view of major portions of adry cleaner1 as a laundry apparatus according to one embodiment of the present invention. Reference will be made to directional arrows shown inFIG. 1 for directional notation.
• Referring toFIG. 1, thedry cleaner1 is, for example, for business use, and includes a generally rectangular box-shapedmain body2, and a tank/filter kit3 (seeFIG. 2).
• Themain body2 includes a rack-like frame2a. Anouter tub4 and adrum5 accommodated in theouter tub4 are provided within theframe2a. Theouter tub4 and thedrum5 function as a laundry containing tub. Theframe2ais fixed to a floor. Anoperation panel2bis attached to a front face portion of theframe2aabove theouter tub4, specifically, at around a level of user's eyes. A user operates operation buttons (not shown) of theoperation panel2bto cause thedry cleaner1 to perform desired operations, and the operation status of thedry cleaner1 is displayed on a display panel (not shown) of theoperation panel2b.
• Theouter tub4 is of a generally rectangular box shape, and has a generally cylindrical space defined therein. Theouter tub4 has an outer tub opening4aformed in a front wall thereof as communicating with the inside thereof and having a round shape as seen from the front side. Anannular metal rim4bis fitted along the periphery of the outer tub opening4a. Anannular packing4cis attached to an inner peripheral front edge of therim4b. Therim4bhas ahinge4dprovided at a left edge portion thereof, and anengagement projection4eprovided at a right edge portion thereof. A door (not shown) is attached to thehinge4dso as to be pivotal about a pivot shaft of thehinge4dto open and close the outer tub opening4a. The door (not shown) has an engagement projection (not shown) provided at a portion thereof opposite from the hinge side. When the door (not shown) closes the outer tub opening4a, the engagement projection (not shown) of the door is engaged with theengagement projection4eof therim4b, whereby the door (not shown) is locked with the outer tub opening4aclosed.
• Four corners of a bottom face of theouter tub4 are connected to theframe2aviadampers2c. Therefore, even if theouter tub4 vibrates during the operation of thedry cleaner1, the vibrations of theouter tub4 are damped by thedampers2cand hence prevented from being propagated around thedry cleaner1 through theframe2a.
• Thedrum5 has a generally cylindrical hollow shape, and is disposed with its center shaft extending generally horizontally, specifically, extending anteroposteriorly. Thedrum5 is rotatable about the center shaft thereof. Thedrum5 has adrum opening5aformed in a front wall thereof at a position corresponding to the outer tub opening4aas communicating with the inside of thedrum5. Thedrum opening5ais anteroposteriorly opposed to the outer tub opening4a. Therefore, laundry can be loaded into thedrum5 through the outer tub opening4aand the drum opening5awith the door (not shown) being opened. A plurality ofbaffles5bare provided on an inner peripheral surface of thedrum5 as projecting toward the center shaft.
Internal Construction of Dry Cleaner
• FIG. 2 is a pipeline diagram of thedry cleaner1. With reference toFIG. 2, the internal construction of thedry cleaner1 will hereinafter be described in detail.
• Theouter tub4 has an air inlet6 (inlet) through which air is introduced into thedrum5, and an air outlet7 (outlet) through which the air is expelled from thedrum5. A circulation duct8 (air flow passage) is connected to theair outlet7 and the air inlet6. That is, the circulation duct8 is a closed circuit which connects theair outlet7 and the air inlet6 to each other.
• Thedry cleaner1 is an apparatus designed to perform a dry cleaning process with the use of a special solvent such as a petroleum-based solvent or a silicone-based solvent (the silicone-based solvent is used in this embodiment). The dry cleaning process is advantageous in that laundry is less liable to shrink and oil stains are more easily removed as compared with a water cleaning process in which the laundry is washed with water. On the other hand, it is not desirable to release the solvent used for the dry cleaning to the external environment. Therefore, the dry cleaner according to this embodiment is of a type which is adapted to recover all the used solvent.
• More specifically, a predetermined amount of solvent supplied from atank31 to be described later is contained in theouter tub4, and the laundry is washed with the solvent in a washing process. After the washing process, the solvent is recovered from theouter tub4 into thetank31. Further, thedrum5 is rotated at a higher speed to remove residual solvent from the laundry. The removed solvent is also recovered into thetank31. Thereafter, a drying process is performed to dry the laundry by circulating the air between the circulation duct8 and thedrum5 while rotating thedrum5 at a lower speed. The vapor of the solvent resulting from vaporization of the solvent from the laundry in the drying process is also recovered by condensation thereof. During the rotation of thedrum5, the laundry is agitated by thebaffles5b. Thus, the laundry is efficiently washed and dried.
• In the drying process, ablower10 is rotated by a blower motor9, whereby the air in thedrum5 is circulated from theair outlet7 into the air inlet6 through the circulation duct8. Drying coolers11 and12 are provided in the circulation duct8, and a drying heater13 (heating unit) is provided adjacent the air inlet6. The air flowing out of thedrum5 into the circulation duct8 through theair outlet7 contains the vaporized solvent (solvent gas). The air containing the solvent gas is cooled by the drying coolers11 and12, so that the solvent gas in the air is liquefied. That is, the solvent-containing air flowing through the circulation duct8 is cooled by the drying coolers11 and12, whereby the solvent is condensed and recovered from the air. Thereafter, the air is heated by the dryingheater13, and the heated air is supplied as drying air into thedrum5 through the air inlet6. In thedrum5, the heated air is heat-exchanged with the laundry, whereby the solvent contained in the laundry is vaporized. The vaporized solvent flows together with the air into the circulation duct8 through theair outlet7. This cycle in which the air in thedrum5 is circulated between thedrum5 and the circulation duct8 is repeated, thereby drying the laundry in thedrum5. Thedry cleaner1 is configured such that the drying air from the air inlet6 is supplied to the laundry in thedrum5 through the outer tub opening4aand the drum opening5a. Thedrum opening5ais an opening having the greatest size in thedrum5, so that the drying air can be efficiently supplied to the laundry through the drum opening5a. Further, the air in thedrum5 is circulated through the circulation duct8. Therefore, the air heated by the dryingheater13 and supplied into thedrum5 is heat-exchanged with the laundry in thedrum5 to vaporize moisture (solvent) from the laundry, and then reused for the drying of the laundry rather than being expelled together with the vaporized moisture to the outside. Accordingly, thedry cleaner1 is environmentally friendly.
• Meanwhile, the solvent is flammable. Therefore, there is the danger of ignition or explosion of the vaporized solvent unless the temperature of the heated air is reliably controlled in the drying process.
• For detecting the temperature of the heated air supplied into thedrum5 from the air inlet6, a druminlet temperature thermistor14 and an inletover-temperature preventing thermistor15 are provided downstream of the drying heater13 (on a downstream side with respect to an air flow direction—this definition holds true for the following description) in the circulation duct8. Though not shown, the inlet over-temperature preventingthermistor15 is connected to a transistor circuit, and configured such that the circuit is cut off through the transistor, for example, when a temperature of 95° C. is detected. Therefore, the inlet over-temperature preventingthermistor15 is advantageous in that it ensures more accurate detection of an operation temperature and a quicker response to the temperature than a thermostat.
• For detecting the temperature of the air expelled from theair outlet7, a drum outlet temperature thermistor16 (temperature sensor) and an abnormal outlettemperature judging thermistor17 which monitors the drumoutlet temperature thermistor16 to check whether or not the drumoutlet temperature thermistor16 malfunctions are provided in the circulation duct8. For detecting the temperature of the air cooled by a downstream one of the two drying coolers11 and12, acooler temperature thermistor18 and a coolerover-temperature preventing thermistor19 which constitutes a part of a safety circuit are provided in the circulation duct8.
• Further, anaspiration port20 and a gate valve V14 are provided between the drying cooler12 and the dryingheater13 in the circulation duct8 for regulating the internal pressure of the circulation duct8 when the circulation duct internal pressure is excessively increased. Normally, theaspiration port20 is opened, and the gate valve V14 is opened to permit the air to flow through the circulation duct8. Further, the circulation duct8 has an explosion protection port26 which, if the solvent gas-containing air flowing through the circulation duct8 happens to be ignited to cause explosion, releases the blast of the explosion. The explosion protection port26 is biased in a closing direction by a spring not shown.
• The drying coolers11 and12 are connected to a freezingmachine23 throughcoolant passages22a,22band22c. The freezingmachine23 is disposed outside themain body2. When a drying cooler electromagnetic valve2Y inserted in thecoolant passage22ais opened, a coolant (e.g., cold water) flows from the freezingmachine23 into the drying cooler12 and the drying cooler11 through thecoolant passages22aand22b, whereby the drying cooler12 and the drying cooler11 perform a cooling operation. The drying coolers11 and12 are herein connected in series with each other to the freezingmachine23, but may be connected in parallel with each other to the freezingmachine23. More specifically, thecoolant passages22aand22cmay be provided for each of the drying coolers11 and12 to supply the coolant individually to the drying coolers11 and12 from the freezingmachine23. Of course, freezingmachines23 may be respectively provided for the drying coolers11 and12.
• The dryingheater13 is a so-called radiator which radiates heat of steam passing therethrough from fins thereof to heat the ambient atmosphere, and is connected to steampassages24 and25. More specifically, thesteam passage24 connects an external steam source to the dryingheater13. An inlet valve V20 is inserted in thesteam passage24. Thesteam passage24 is branched into a firststeam supply passage24ahaving a relatively great passage diameter and a secondsteam supply passage24bhaving a relatively small passage diameter between the dryingheater13 and the inlet valve V20. A first valve V27 (first supply valve) is inserted in the firststeam supply passage24a, and a second valve V28 (second supply valve) is inserted in the secondsteam supply passage24b. On the other hand, thesteam passage25 is a passage through which the steam supplied from thesteam passage24 to the dryingheater13 is expelled to the outside.
• With the inlet valve V20 and the first valve V27 and/or the second valve V28 being opened, steam (e.g. steam at 110 to 120° C.) is supplied to the dryingheater13, whereby the dryingheater13 heats the air in the circulation duct8 by the steam. Since the firststeam supply passage24aand the secondsteam supply passage24bare different in steam supply capacity, the steam may be supplied to the dryingheater13 from one or both of the firststeam supply passage24aand the secondsteam supply passage24bas required. The supply of the steam to the dryingheater13 will be described in detail later.
• In the drying process, the rotation of the blower motor9, and the opening and closing of the inlet valve V20 and the first valve V27 and/or the second valve V28 are typically controlled based on temperatures detected by the druminlet temperature thermistor14, the drumoutlet temperature thermistor16 and thecooler temperature thermistor18.
• The tank/filter kit3 includes thetank31 which stores the solvent, and afirst filter32 and asecond filter33 which are connected in series for filtering the solvent pumped up from thetank31. A pump-uppipe34 is connected to a bottom of thetank31 at one end thereof. A valve V1 is inserted in the pump-uppipe34. The other end of the pump-uppipe34 is connected to ajunction35. Asolvent pump36 is connected to thejunction35 on its suction side and to an inlet of a three-way valve V6 on its ejection side. One outlet of the three-way valve V6 is connected to one end of aflow pipe37, and the other end of theflow pipe37 is connected to thetank31 via a valve V19. Theflow pipe37 is branched at its intermediate portion (between the three-way valve V6 and the valve V19) to be connected to the serial connection of thefirst filter32 and thesecond filter33. Aflow pipe38 is connected to an outlet of thesecond filter33, and a distal end of theflow pipe38 is connected to an inlet of asolvent heat exchanger39 provided in themain body2.
• Abypass pipe40 is connected to the other outlet of the three-way valve V6 at one end thereof, and the other end of thebypass pipe40 joins theflow pipe38 connected to the inlet of thesolvent heat exchanger39.
• Therefore, the solvent is applied to thesolvent heat exchanger39 through thefirst filter32 and thesecond filter33, or applied to thesolvent heat exchanger39 through thebypass pipe40 with thefilters32 and33 bypassed by switching between the outlets of the three-way valve V6.
• Asteam pipe41 and acoolant pipe42 are provided in thesolvent heat exchanger39. Thesteam pipe41 and thecoolant pipe42 are each wound, for example, in a coil shape.Steam passages43 and44 are connected to thesteam pipe41. Thesteam passage43 connects thesteam pipe41 and thesteam passage24, and a valve V21 is inserted in thesteam passage43. On the other hand, thesteam passage44 is a passage through which the steam supplied from thesteam passage43 to thesteam pipe41 is discharged to the outside. With the valve V21 being opened, the steam flows into thesteam pipe41 through thesteam passage43 to be discharged through thesteam passage44. While the solvent passes through thesolvent heat exchanger39, thesteam pipe41 at a high temperature exchanges heat with the solvent to heat the solvent. On the other hand,coolant passages45aand45bare connected to thecoolant pipe42, and a solvent coolerelectromagnetic valve3Y is inserted in thecoolant passage45a. With the solvent coolerelectromagnetic valve3Y being opened, the coolant passes through thecoolant pipe42. While the solvent passes through thesolvent heat exchanger39, thecoolant pipe42 exchanges heat with the solvent to cool the solvent. By controlling the opening and closing of the valve V21 and the opening and closing of the solvent coolerelectromagnetic valve3Y, thesolvent heat exchanger39 is switched to heat or cool the solvent, whereby the temperature of the solvent passing through thesolvent heat exchanger39 is regulated at a desired temperature.
• Aflow pipe46 is connected to an outlet of thesolvent heat exchanger39 at one end thereof. The other end of theflow pipe46 is connected to an inlet of a three-way valve V9. Aliquid temperature thermistor47 for measuring the temperature of the solvent and a liquidover-temperature preventing thermistor48 for preventing a liquid temperature from being increased to a predetermined temperature or higher are provided in theflow pipe46.
• A soap concentration sensor50 is provided downstream of these two thermistors in theflow pipe46.
• Aliquid supply pipe51 is connected to one outlet of the three-way valve V9 at one end thereof and to theouter tub4 at the other end thereof, so that the solvent can be supplied into thedrum5. Afeedback pipe52 is connected to the other outlet of the three-way valve V9 at one end thereof and to thetank31 at the other end thereof.
• Arecovery pipe62 for recovering the solvent condensed by the drying coolers11 and12 in the circulation duct8 has one end connected to a portion of the circulation duct8 below the drying coolers11 and12. The other end of therecovery pipe62 is connected to awater separator63. In thewater separator63, water contained in the recovered solvent is separated, and the separated water is drained through adrain pipe64. Then, the recovered solvent is returned into thetank31 through arecovery pipe65.
• Theouter tub4 has adrain port55 provided at its lowermost portion, and a liquidsurface detection chamber56 is connected to thedrain port55. The liquidsurface detection chamber56 is provided with two liquid surface switches, i.e., a standardliquid surface switch57 and a drainliquid surface switch58. The liquidsurface detection chamber56 also serves as a trap which traps a button or the like dislodged from the laundry and falling through thedrain port55 during the washing process.
• Arecovery pipe59 is connected to a lower end of the liquidsurface detection chamber56 at one end thereof. A valve V4 is inserted in therecovery pipe59. The other end of therecovery pipe59 is connected to thejunction35.
• Asoap pipe61 is connected to asoap container60 at one end thereof and to thejunction35 at the other end thereof. A valve V17 is inserted in thesoap pipe61.
• Next, the flow of the solvent will be described with reference to the pipeline diagram ofFIG. 2.
• In the washing process, the solvent stored in thetank31 is supplied into the drum5 (the outer tub4). At this time, thesolvent pump36 is driven with the valve V1 being opened, with the three-way valve V6 being opened to theflow pipe37 and with the valve V19 being closed. Thus, the solvent in thetank31 flows into theflow pipe38 through thefirst filter32 and thesecond filter33 and, after the temperature of the solvent is regulated by thesolvent heat exchanger39, the solvent flows to the three-way valve V9 through theflow pipe46. With the three-way valve V9 being opened to theliquid supply pipe51, the solvent is supplied into theouter tub4 through theliquid supply pipe51. During the supply of the solvent, the valve V4 is closed. The amount of the solvent contained in theouter tub4 is detected by the standardliquid surface switch57 and, when a predetermined amount of the solvent (suitable for the washing) is contained in theouter tub4, the valve V9 is switched so as to close theliquid supply pipe51 and open thefeedback pipe52.
• A soap is preliminarily mixed with the solvent contained in thetank31 and, when the solvent passes through theflow pipe46, the concentration of the soap in the solvent is measured by the soap concentration sensor50. If the soap concentration is lower, the soap is pumped up from thesoap container60 through thesoap pipe61 with the valve V17 being opened, and mixed with the supplied solvent.
• During the supply of the solvent to theouter tub4, the three-way valve V6 may be switched, as required, to cause the solvent to bypass thefilters32,33, so that the solvent is applied to thesolvent heat exchanger39 through thebypass pipe40 and then supplied to theouter tub4.
• In a solvent draining and removing process, thesolvent pump36 is driven with the valve V4 being opened and with the valve V1 being closed. The solvent is returned into thetank31 with the three-way valve V6 being opened to theflow pipe37 and with the valve V19 being opened.
• Alternatively, the solvent flowing through theflow pipe37 may be caused to flow through thefilters32 and33, theflow pipe38, thesolvent heat exchanger39 and theflow pipe46 with the valve V19 being closed, and then flow through the three-way valve V9 and thefeedback pipe52 back into thetank31. Thus, the solvent drained from theouter tub4 after the washing process and the solvent removed from the laundry by the centrifugal force are passed through thefilters32 and33 for decontamination, and then returned into thetank31.
Steam Supply to Drying Heater
• FIG. 3 is a block diagram showing an arrangement for a control operation for the supply of the steam to the dryingheater13 in thedry cleaner1.
• The supply of the steam to the dryingheater13 will hereinafter be described in detail.
• As shown inFIG. 3, thedry cleaner1 includes a control section81 (controller) including, for example, a microcomputer and the like. Thecontrol section81 includes a hardware-based or software-basedtimer82.
• The drum outlet temperature detected by the drumoutlet temperature thermistor16 is provided to thecontrol section81. Thecontrol section81 opens and closes the inlet valve V20, the first valve V27 and the second valve V28 individually or simultaneously based on the provided drum outlet temperature. Here, the drum outlet temperature is the temperature of the air heat-exchanged with the laundry in thedrum5, and is detected as an actual laundry drying temperature, whereby a laundry drying state is accurately detected. When power supply to thedry cleaner1 is on, thecontrol section81 constantly opens the inlet valve V20. When an abnormal condition such as malfunction of the steam source occurs, thecontrol section81 immediately closes the inlet valve V20.
• FIG. 4 is a flow chart for explaining the control operation for the steam supply to the dryingheater13 in the drying process.
• When the drying process is started, thecontrol section81 causes thetimer82 to start time measurement (Step S1). Then, thecontrol section81 references time measurement data of thetimer82, i.e., an elapsed time T1 from the start of the drying process (Step S2). If the elapsed time T1 exceeds a predetermined period (a driving period predetermined for the drying process) (Yes in Step S2), thecontrol section81 ends the drying process. On the other hand, if the elapsed time T1 is within the predetermined period (No in Step S2), thecontrol section81 opens the second valve V28 to supply the steam from the secondsteam supply passage24bto the drying heater13 (Step S3). After a lapse of, for example, two seconds from the opening of the second valve V28 (Yes in Step S4), thecontrol section81 opens the first valve V27 (Step S5). Thus, the steam is supplied to the dryingheater13 from the firststeam supply passage24aas well as the secondsteam supply passage24b. If two seconds have not elapsed from the opening of the second valve V28 (No in Step S4), thecontrol section81 maintains only the second valve V28 in the opened state. Thus, the second valve V28 is first opened and then the first valve V27 is opened when the heating of the air is started in the drying process. Therefore, a relatively small amount of steam is first supplied to the dryingheater13, and then a relatively great amount of steam is supplied to the dryingheater13. Thus, a steam pressure in the dryingheater13 is increased stepwise. If the opening of the first valve V27 preceded the opening of the second valve V28, the steam pressure in the dryingheater13 would be steeply increased, and an impact of the steep increase in steam pressure would damage the dryingheater13, for example, would make a hole in the dryingheater13. In thedry cleaner1, however, the steam pressure in the dryingheater13 is increased stepwise, so that the impact exerted on the dryingheater13 by the steam pressure is alleviated. This extends the service life of the dryingheater13.
• If the drum outlet temperature (measured temperature) detected by the drumoutlet temperature thermistor16 exceeds a target temperature (Yes in Step S6) with the first valve V27 and the second valve V28 being opened (Step S5), thecontrol section81 references the elapsed time T1 again (Step S7). Here, the target temperature is a target level of the laundry drying temperature, for example, 70° C. If the drum outlet temperature (measured temperature) does not exceed the target temperature (No in Step S6), thecontrol section81 returns to Step S2 to reference the elapsed time T1. If the elapsed time T1 is within the predetermined period (No in Step S2), a control sequence from Step S3 to Step S6 is performed. If the elapsed time T1 exceeds the predetermined period (Yes in Step S2), thecontrol section81 ends the drying process.
• If the elapsed time T1 is within the predetermined period in Step S7 (No in Step S7), thecontrol section81 closes the first valve V27 (Step S8). Then, thecontrol section81 judges whether the measured temperature exceeds an upper limit temperature which is higher by e.g. 2° C. than the target temperature (Step S9). If the measured temperature exceeds the upper limit temperature (Yes in Step S9), thecontrol section81 closes the second valve V28 (Step S10). Thus, both the first valve V27 and the second valve V28 are closed, so that the supply of the steam to the dryingheater13 is stopped. If the measured temperature is thereafter reduced to a lower limit temperature which is lower by e.g. 2° C. than the target temperature (Yes in Step S11), thecontrol section81 opens the second valve V28 again (Step S13), and returns to Step S7. On the other hand, if the measured temperature is not reduced to the lower limit temperature after the second valve V28 is closed in Step S10 (No in Step S11) and the elapsed time T1 is within the predetermined period (No in Step S12), thecontrol section81 maintains the first valve V27 and the second valve V28 in the closed state. On the other hand, if the elapsed time T1 exceeds the predetermined period (Yes in Step S12), thecontrol section81 ends the drying process.
• If the elapsed time T1 exceeds the predetermined period in Step S7 (Yes in Step S7), thecontrol section81 ends the drying process.
• If the measured temperature does not exceed the upper limit temperature in Step S9 (No in Step S9), thecontrol section81 judges whether the measured temperature is below the lower limit temperature (Step S14). If the measured temperature is below the lower limit temperature (Yes in Step S14), thecontrol section81 opens the first valve V27 again (Step S15). Such a control operation is performed, for example, on the condition that it is supposedly impossible to increase the measured temperature by opening the second valve V28 alone because of an extremely low ambient temperature around thedry cleaner1. Therefore, thecontrol section81 opens the first valve V27, so that both the first valve V27 and the second valve28 are in the opened state. Thereafter, thecontrol section81 judges whether the measured temperature exceeds the upper limit temperature (Step S16). If the measured temperature exceeds the upper limit temperature (Yes in Step S16), thecontrol section81 returns to Step S7 to perform a control sequence from Step S7. On the other hand, if the measured temperature does not exceed the upper limit temperature (No in Step S16) and the elapsed time T1 is within the predetermined period (No in Step S17), thecontrol section81 maintains the first valve V27 and the second valve V28 in the opened state. If the elapsed time T1 exceeds the predetermined period (Yes in Step S17), thecontrol section81 ends the drying process.
• If the measured temperature is not below the lower limit temperature in Step S14 (No in Step S14), thecontrol section81 returns to Step S7, and performs the control sequence from Step S7.
• When the measured temperature exceeds the target temperature in Step S6 (Yes in Step S6), thecontrol section81 closes the first valve V27. When the measured temperature is further increased to the upper limit temperature which is higher by the predetermined degree than the target temperature in Step S9 and the subsequent steps (Yes in Step S9), thecontrol section81 closes the second valve V28. When the measured temperature is reduced to the lower limit temperature which is lower by the predetermined degree than the target temperature (Yes in Step S11), thecontrol section81 opens only the second valve V28. That is, where the measured temperature is changed from the target temperature, the drum outlet temperature is controlled by opening and closing the second valve V28 not immediately but after a lapse of a predetermined period. This prevents the second valve V28 from chattering. The control of the drum outlet temperature is achieved by opening and closing only the second valve V28 which has a relatively low steam supply capacity. Therefore, a sudden change in drum outlet temperature is suppressed as compared with the case in which the control of the drum outlet temperature is achieved by opening and closing the first valve V27 having a relatively high steam supply capacity, so that the drum outlet temperature can be stably controlled.
• FIG. 5 is a diagram illustrating changes in drum outlet temperature observed with time in the drying process with and without the inventive arrangement.
• In thedry cleaner1, as described above, the firststeam supply passage24ahaving a relatively great passage diameter and the secondsteam supply passage24bhaving a relatively small passage diameter are independently provided for supplying the steam to the drying heater13 (seeFIG. 2). A relatively great amount of steam is supplied from the firststeam supply passage24ato the dryingheater13 by opening the first valve V27 provided in the firststeam supply passage24a. On the other hand, a relatively small amount of steam is supplied to the dryingheater13 by opening the second valve V27 provided in the secondsteam supply passage24b.
• Therefore, the drum outlet temperature (the laundry drying temperature or the measured temperature) can be increased to the target temperature in a relatively short time, as indicated by a solid line inFIG. 5, by mainly opening the first valve V27. After the laundry drying temperature reaches the target temperature, a drastic fluctuation in laundry drying temperature can be suppressed by mainly opening and closing the second valve V28. That is, the first valve V27 and the second valve V28 are selectively used for regulating the laundry drying temperature. Therefore, the opening/closing frequencies of the first valve V27 and the second valve V28 are reduced as compared with a case in which a single supply valve is used for regulating the laundry drying temperature (see a broken line inFIG. 5).
• Where the single supply valve (hereinafter referred to as “comparative valve”) is used for regulating the laundry drying temperature, the amount of the steam to be supplied is typically set at a value between the amount of steam to be supplied with the first valve V27 being opened and the amount of steam to be supplied with the second valve V28 being opened. In this case, greater time is required for increasing the laundry drying temperature to the target temperature as compared with the case in which the first valve V27 is used. If the comparative valve is opened for regulating the laundry drying temperature at around the target temperature, the laundry drying temperature is quickly increased to the upper limit temperature as indicated by a broken line in an enlarged view inFIG. 5. Therefore, the comparative valve should be closed immediately after having been opened. This increases the opening/closing frequency of the comparative valve, thereby reducing the service life of the comparative valve. Where the second valve V28 is mainly used for regulating the laundry drying temperature at around the target temperature, however, greater time is required for increasing the laundry drying temperature to the upper limit temperature because of a lower steam supply capacity of the second valve V28 as compared with the case in which the comparative valve is used. Therefore, the opening/closing frequency of the second valve V28 is correspondingly reduced. Since the second valve V28 is mainly used for regulating the laundry drying temperature at around the target temperature, the opening/closing frequency of the first valve V27 is also reduced. In thedry cleaner1, the opening/closing frequencies of the first valve V27 and the second valve V28 are thus reduced, making it possible to stably regulate the laundry drying temperature while preventing the reduction in the service lives of these valves.
• It should be understood that the present invention be not limited to the embodiment described above, but various modifications may be made within the purview of the appended claims.
• In the embodiment described above, the laundry drying temperature is increased to the target temperature at the highest rate when the first valve V27 and the second valve V28 are opened, and the laundry drying temperature increasing rate is reduced when the first valve V27 is opened and the second valve V28 is closed. When the first valve V27 is closed and the second valve V28 is opened, the laundry drying temperature increasing rate is the lowest. Therefore, the first valve V27 and the second valve V28 may be selectively opened and closed in different combinations. In this case, the laundry drying temperature can be further optimally controlled without the use of a complicated and expensive supply valve which is capable of controlling the opening degree of the valve.
• The rotation shaft of thedrum5 is not necessarily required to extend horizontally, but may be inclined at a predetermined angle (e.g., not greater than 30 degrees) with respect to a horizontal plane.
• This application corresponds to Japanese Patent Application No. 2006-314580 filed in the Japanese Patent Office on Nov. 21, 2006, the disclosure of which is incorporated herein by reference.

Claims (4)

1. A laundry apparatus comprising:

a laundry containing tub having an inlet and configured to contain laundry;

an air flow passage connected to the inlet of the laundry containing tub to allow air to flow into the laundry containing tub from the inlet;

heating unit which heats the air in the air flow passage by steam;

a first steam supply passage having a greater passage diameter for supplying the steam to the heating unit;

a second steam supply passage provided separately from the first steam supply passage and having a smaller passage diameter for supplying the steam to the heating unit;

a first supply valve provided in the first steam supply passage to be opened and closed for permitting and preventing the supply of the steam to the heating unit; and

a second supply valve provided in the second steam supply passage to be opened and closed for permitting and preventing the supply of the steam to the heating unit.

2. The laundry apparatus according toclaim 1,

wherein the laundry containing tub has an outlet,

wherein the air flow passage includes a circulation duct connected to the outlet of the laundry containing tub and configured to allow the air flowing into the laundry containing tub through the inlet to flow out through the outlet to circulate the air in the laundry containing tub.

3. The laundry apparatus according toclaim 2, further comprising controller which opens and closes the first supply valve and the second supply valve individually or simultaneously,

wherein the controller is configured to first open the second supply valve and then the first supply valve when the heating of the air is started.

4. The laundry apparatus according toclaim 3, further comprising a temperature sensor for detecting an air temperature at the outlet,

wherein the controller is configured to close the first supply valve when the temperature detected by the temperature sensor exceeds a target temperature, close the second supply valve when the temperature detected by the temperature sensor is further increased to an upper limit temperature which is higher by a predetermined degree than the target temperature, and open only the second supply valve when the temperature detected by the temperature sensor is reduced to a lower limit temperature which is lower by a predetermined degree than the target temperature.

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