US20040197204A1 - Variable displacement mechanism for scroll type compressor - Google Patents

Abstract

A variable displacement mechanism for a scroll type compressor includes a by-pass passage, a valve chamber, a valve plate and an actuator. The by-pass passage serves to interconnect a compression chamber in a process of volume reduction with a suction pressure region and includes a first valve hole. The valve chamber serves to communicate with the first valve hole and forms a valve seat surface around an opening of the first valve hole. The valve plate has an end surface that faces the valve seat surface. The valve plate is arranged in the valve chamber so as to selectively move between an open position, where the end surface is separated from the valve seat surface to open the first valve hole, and a close position, where the end surface contacts the valve seat surface to close the first valve hole. The actuator serves to actuate the valve plate.

Description

BACKGROUND OF THE INVENTION
• The present invention relates to a scroll type compressor for use in a vehicle air conditioner and more particularly to a variable displacement mechanism for varying the displacement of the scroll type compressor.[0001]
• A variable displacement mechanism of such type is disclosed in Japanese Unexamined Patent Publication No. 2001-32787. A compression chamber communicates with a suction pressure region through a by-pass passage in a process of volume reduction. A spool valve opens and closes the by-pass passage to vary the displacement of the scroll type compressor.[0002]
• In the spool valve, a spool is slidably accommodated in a cylinder. The spool includes a valve portion and a rod portion. The valve portion has an outer diameter that is substantially equal to an inner diameter of the cylinder. Also, the valve portion opens and closes the by-pass passage. The rod portion has an outer diameter that is smaller than the inner diameter of the cylinder, and partially constitutes the by-pass passage.[0003]
• However, in the variable displacement, the spool is formed to open and close a port that is open at an inner circumferential surface of the cylinder (an inner surface of the cylinder) by the valve portion (a column) of the spool so that it is difficult to arrange a seal member at the valve portion. Therefore, the valve portion of the spool contacts the inner circumferential surface of the cylinder so as to prevent refrigerant gas from leaking from the spool valve.[0004]
• A small clearance between the valve portion of the spool and the inner circumferential surface of the cylinder effectively suppresses the leakage of the refrigerant gas from the by-pass passage. However, as the clearance between the valve portion of the spool and the inner circumferential surface of the cylinder is relatively small, sliding resistance increases between the spool and the cylinder. As a result, problems, such as deterioration in response to displacement variation and enlargement of an actuator for actuating the spool, occur.[0005]
• Accordingly, in a prior art, in view of suppressing the rise of cost for manufacturing a highly accurate clearance, the clearance between the valve portion of the spool and the inner circumferential surface of the cylinder is relatively large. Then, for example, even though the scroll type compressor is tried to operate at a maximum displacement by closing the by-pass passage, a desired maximum displacement cannot be achieved due to the leakage of the refrigerant gas from the spool (the by-pass passage). Namely, performance of the scroll type compressor deteriorates.[0006]
SUMMARY OF THEE INVENTION
• The present invention provides a variable displacement mechanism that reliably seals a by-pass passage for a scroll type compressor.[0007]
• In accordance with the present invention, in a scroll type compressor having a movable scroll member and a fixed scroll member, the movable scroll member and the fixed scroll member define compression chambers therebetween. The compression chambers reduce in volume as the compression chambers are moved radially and inwardly by orbiting the movable scroll member relative to the fixed scroll member. Thus gas is compressed. A suction pressure region is defined in the scroll type compressor. A variable displacement mechanism for the scroll type compressor includes a by-pass passage, a valve chamber, a valve plate and an actuator. The by-pass passage serves to interconnect the compression chamber in a process of volume reduction with the suction pressure region includes a first valve hole. The valve chamber serves to communicate with the first valve hole and forms a valve seat surface around an opening of the first valve hole. The valve plate has an end surface that faces the valve seat surface. The valve plate is arranged in the valve chamber so as to selectively move between an open position, where the end surface is separated from the valve seat surface to open the first valve hole, and a close position, where the end surface contacts the valve seat surface to close the first valve hole. An actuator serves to actuate the valve plate.[0008]
BRIEF DESCRIPTION OF THE DRAWINGS
• The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:[0009]
• FIG. 1 is a longitudinal cross-sectional view of a hybrid compressor according to a preferred embodiment of the present invention;[0010]
• FIG. 2 is a cross-sectional view of the hybrid compressor taken along the line I-I in FIG. 1;[0011]
• FIG. 3A is a partially enlarged cross-sectional view that corresponds to FIG. 1 in a state where a valve plate is located at an open position; and[0012]
• FIG. 3B is a partially enlarged cross-sectional view that corresponds to FIG. 1 in a state where the valve plate is located at a close position.[0013]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• A preferred embodiment according to the present invention will be described. The preferred embodiment applies the present invention to a hybrid compressor C that is a scroll type. The left and right sides of FIG. 1 respectively correspond to the front and rear sides the compressor C.[0014]
• The compressor C will be schematically described. As shown in FIG. 1, the compressor C constitutes a refrigerating cycle of a vehicle air conditioner and includes a[0015]housing11, acompression mechanism12, anelectric motor21 and apower transmission mechanism22. Thecompression mechanism12 and theelectric motor21 are accommodated in thehousing11. Thepower transmission mechanism22 is arranged on an outer wall of thehousing11. Thecompression mechanism12 is a scroll type and has a structure to vary a displacement of the compressor C. Thepower transmission mechanism22 receives power from an engine (internal combustion) E for traveling a vehicle.
• The compressor C is selectively driven by one of power from the engine E through the[0016]power transmission mechanism22 and power from theelectric motor21. Since the compressor C includes theelectric motor21, air conditioning (cooling) is capable of being continuously conducted even when, the engine E is in a stopped state. Therefore, the vehicle air conditioner in the present preferred embodiment is particularly suitable for an idle stop vehicle and a hybrid vehicle.
• The compressor C will be now described in detail. As shown in FIG. 1, the[0017]housing11 includes acasing11aand acover11b.Thecasing11ahas a cylindrical shape with a bottom that corresponds to the front side. Thecover11bis fixed to the rear end of thecasing11a.Arotary shaft13 is rotatably arranged in thehousing11. A throughhole34 is formed at the center of the bottom of thecasing11aof thehousing11 so as to extend therethrough. The front end of therotary shaft13 is interposed into the throughhole34. The front end of therotary shaft13 is rotatably supported by thehousing11 through abearing35 in the throughhole34. Alip seal37 is arranged on the front end of therotary shaft13 in thehousing11 for sealing the rotary-shaft13.
• A[0018]shaft support member31 is fixed on the rear end side of thecasing11ain thehousing11. A throughhole31ais formed at the center of theshaft support member31 so as to extend therethrough. The rear end of therotary shaft13 is interposed into the throughhole31aof theshaft support member31 and is rotatably supported by theshaft support member31 through abearing32 in the throughhole31a.
• The[0019]power transmission mechanism22 includes apulley17 and anelectromagnetic clutch18. Thepulley17 is rotatably supported at the outside of thehousing11 and transmits the power from the engine E to therotary shaft13. When theelectromagnetic clutch18 is switched on (energized), the electromagnetic clutch18 permits power transmission from thepulley17 to therotary shaft13. When theelectromagnetic clutch18 is switched off (de-energized), the electromagnetic clutch18 blocks the power transmission.
• A[0020]stator15 is provided on the inner circumferential surface of thecasing11aof thehousing11 and is located on the front side of thehousing11. Arotor14 is fixed to therotary shaft13 in thehousing11 so as to be located inside thestator15. Theelectric motor21 includes thestator15 and therotor14. Theelectric motor21 integrally rotates therotor14 and therotary shaft13 by supplying electric power to thestator15.
• A fixed[0021]scroll member41 is fixedly accommodated at the opening end of thecasing11ain thehousing11. The fixedscroll member41 includes a fixedbase plate61 that has a disc-shape, an outercircumferential wall62 that has a cylindrical shape and a fixedspiral wall63. The outercircumferential wall62 extends from the outer periphery of the fixedbase plate61. The fixedspiral wall63 extends from the fixedbase plate61 inside the outercircumferential wall62. The end surface of the outercircumferential wall62 is joined to the rear surface of theshaft support member31.
• A[0022]crankshaft43 is provided at the rear end surface of therotary shaft13 and is offset from an axis L of therotary shaft13 in an eccentric direction. Thecrankshaft43 is inserted in a bushing51. Amovable scroll member42 is supported by the bushing51 through a bearing52 so as to face the fixedscroll member41 and so as to rotate relative to the fixedscroll member41. Themovable scroll member42 includes a movable base plate65 that has a disc-shape and amovable spiral wall66 that extends from the movable base plate65 toward the fixedscroll member41.
• The[0023]movable spiral wall66 of themovable scroll member42 is engaged with the fixedspiral wall63 of the fixedscroll member41. The end surfaces of the fixed andmovable spiral wall63 and66 respectively contact the movable and fixedbase plates65 and61. Therefore, the fixedbase plate61 and the fixedspiral wall63 of the fixedscroll member41 and the movable base plate65 and themovable spiral wall66 of themovable scroll member42 definecompression chambers67.
• A self-[0024]rotation preventing mechanism68 is arranged between the movable base plate65 of themovable scroll member42 and theshaft support member31. The self-rotation preventing mechanism68 is constituted of a plurality ofcylindrical recesses68aand a plurality ofpins68b.The cylindrical recesses68aare formed at the back surface (the front surface) of the movable base plate65. Thepins68bare mounted on the rear end surface of theshaft support member31 and is loosely fitted in the correspondingcylindrical recesses68a.
• A[0025]suction chamber69 or a suction pressure region is defined between the outercircumferential wall62 of the fixedscroll member41 and the outer circumferential portion of themovable spiral wall66 of themovable scroll member42. Aninlet50 is formed in the outer circumferential wall of thecasing11 a of thehousing11 so as to correspond to an accommodating space for theelectric motor21. An external conduit is connected to theinlet50 and leads to a heat exchanger on a low-pressure side in an external refrigerating circuit (not shown). Asuction passage39 is formed in the outer circumferential portion of theshaft support member31 in thehousing11 for interconnecting the accommodating space for theelectric motor21 with thesuction chamber69. Therefore, low-pressure refrigerant gas from the external refrigerating circuit is introduced into thesuction chamber69 through theinlet50, the accommodating space for theelectric motor21 and thesuction passage39. The suction refrigerant gas with a relatively low temperature passes near theelectric motor21. Therefore, heat environmental of theelectric motor21 is satisfactory.
• A first[0026]accommodating recess61bis formed on a part of aback surface61aof the fixedbase plate61 of the fixedscroll member41 in the range from the adjacent center portion to the adjacent outer periphery. The firstaccommodating recess61bis closed by thecover11b,thereby defining adischarge chamber70 as a discharge pressure region between thefixed scroll member41 and thecover11bin thehousing11. Anoutlet53 is formed in thecover11b.An external conduit is connected to thedischarge chamber70 through theoutlet53 and leads to a heat exchanger on a high-pressure side in the external refrigerating circuit (not shown).
• A[0027]discharge hole61cas a discharge passage is formed in the center of the fixedbase plate61 of the fixedscroll member41 so as to extend therethrough in a direction of the axis L and interconnects thecompression chamber67 near the center of the fixedbase plate61 with thedischarge chamber70. Adischarge valve55 constituted of a reed valve is arranged at the fixedscroll member41 in thedischarge chamber70 for opening and closing thedischarge hole61c.Aretainer56 is fixed to the fixedscroll member41 in thedischarge chamber70 to restrict the opening degree of thedischarge valve55.
• When the[0028]rotary shaft13 is rotatively driven by the engine E or theelectric motor21, themovable scroll member42 orbits around the axis of the fixed scroll member41 (the axis L of the rotary shaft13) through thecrankshaft43 in thecompression mechanism12. At this time, the self-rotation preventing mechanism68 prevents themovable scroll member42 from self-rotating while allowing themovable scroll member42 to orbit around the axis of the fixedscroll member41.
• As the[0029]compression chambers67 are moved radially and inwardly by the orbital movement of themovable scroll member42 relative to the fixedscroll member41, thecompression chambers67 reduce in volume. Thereby, the low-pressure refrigerant gas introduced from thesuction chamber69 into thecompression chambers67 is compressed. After compression, the high-pressure refrigerant gas is discharged from thedischarge hole61cinto thedischarge chamber70 through thedischarge valve55.
• A variable displacement mechanism of the compressor C will be now described. As shown in FIGS. 2 and 3A, a second[0030]accommodating recess61dis formed on theback surface61aof the fixedbase plate61 of the fixedscroll member41 The secondaccommodating recess61dhas a horseshoe shape (an annular shape of which a part is removed therefrom) so as to avoid the firstaccommodating recess61b.The opening of the secondaccommodating recess61dis closed by the end surface of thecover11b,thereby defining avalve chamber45. Avalve plate46 is movably accommodated in thevalve chamber45.
• The[0031]valve plate46 has a planar shape and a horseshoe shape so as to be fitted in the secondaccommodating recess61d.In other word, thedischarge hole61cis arranged at the center (a through hole) of thevalve plate46, and thevalve plate46 is formed so as to avoid thedischarge hole61c.An O-ring47 is attached on the outer circumferential surface of thevalve plate46. Thevalve plate46 is slidable relative to the inner circumferential surface of thevalve chamber45 through the O-ring47.
• The[0032]valve plate46 is arranged to divide thevalve chamber45 into acommunication chamber48 on the side of the fixedscroll member41 and aback pressure chamber49 on a side of thecover11b.The O-ring47 on thevalve plate46 blocks between thecommunication chamber48 and theback pressure chamber49. Avalve seat surface48ahaving a horseshoe-shape is formed in the fixedbase plate61 in thecommunication chamber48 so as to face a plate surface (hereinafter referred to as a front end surface)46aof thevalve plate46, which has a horseshoe-shape. Thevalve plate46 is arranged along the fixedbase plate61 in such a manner that the front end surface46aof thevalve plate46 is parallel to theback surface61aof the fixedbase plate61.
• A[0033]first valve hole61 e is formed in the fixedbase plate61 of the fixedscroll member41 so as to extent therethrough in the direction of the axis L. One end of thefirst valve hole61eis open to thecompression chamber67 in a process of volume reduction, and the other end of thefirst valve hole61eis open to thecommunication chamber48 at thevalve seat surface48aof the fixedbase plate61. Thefirst valve hole61eis plurally provided. Each of the first valve holes61einterconnects thecompression chamber67 with thecommunication chamber48 at a position that is different from each other. The first valve holes61ecommunicate with thecompression chamber67 in the process of volume reduction by turns during time when thecompression chamber67 at an initial position of volume reduction that has a maximum volume reduces in volume to a predetermined value (e.g. 20% of the maximum volume).
• A[0034]second valve hole61fis formed in the fixedbase plate61 of the fixedscroll member41 so as to extend therethrough in the direction of the axis L. Thesecond valve hole61finterconnects thecommunication chamber48 with thesuction chamber69. Thesecond valve hole61fis open to thecommunication chamber48 at a position that is different from the first valve holes61eat thevalve seat surface48aof the fixedbase plate61. In the present preferred embodiment, the first valve holes61e,the second,valve hole61fandcommunication chamber48 constitute a by-pass passage that interconnects thecompression chamber67 in the process of volume reduction with thesuction chamber69.
• The[0035]valve plate46 selectively moves between an open position, where the front end surface46aof thevalve plate46 is separated from thevalve seat surface48ain thecommunication chamber48 to simultaneously open the first valve holes61eand thesecond valve hole61f,and a close position, where the front end surface46aof thevalve plate46 contacts thevalve seat surface48ato simultaneously close the first valve holes61eand thesecond valve hole61f.The front end surface46aof thevalve plate46 is provided by arubber coat46b,or a seal member, that is applied to thevalve plate46. Therefore, when thevalve plate46 is located at the close position, the front end surface46areliably seals the first valve holes61eand thesecond valve hole61fdue to elastic deformation of therubber coat46b.
• An actuator for actuating the[0036]valve plate46 is constituted of an urgingspring57, acontrol valve58, and first, second andthird passages71 through73. The urgingspring57 is arranged in thecommunication chamber48. Thecontrol valve58 is constituted of an electromagnetic three-way valve. Thefirst passage71 interconnects thedischarge chamber70 with thecontrol valve58. The second passage72 interconnects theback pressure chamber49 with thecontrol valve58. Thethird passage73 interconnects thesuction chamber69 with thecontrol valve58. Thecontrol valve58 is symbolized in FIGS. 1, 3A and3B for easy understanding. The first andsecond passages71 and72 correspond to a first control passage, and the second andthird passages72 and73 correspond to a second control passage.
• A plurality of the urging[0037]spring57 is arranged between thevalve seat surface48aof the fixedbase plate61 and the front end surface46aof thevalve plate46 so as to avoid the openings of the first and second valve holes61eand61f.Thevalve plate46 is urged by the spring force of the urgingspring57 in a direction in which the front end surface46ais separated from thevalve seat surface48aThe first, second andthird passages71 through73 respectively communicate with first, second andthird ports58a,58band58cof thecontrol valve58.
• In the present preferred embodiment, the[0038]first passage71, an internal1o passage of thecontrol valve58 and the second passage72 constitute a control passage that interconnects theback pressure chamber49 with thedischarge chamber70. Thecontrol valve58 opens and closes the control passage based on an external command. Namely, the communication with the second passage72 is switched between the first andthird passages71 and73 by energizing and de-energizing asolenoid58dbased on the external command. In other word, the communication with theback pressure chamber49 is switched between thesuction chamber69 and thedischarge chamber70 by energizing and de-energizing thesolenoid58d.
• For example, as shown in FIG. 3B, when the[0039]solenoid58dis de-energized, thefirst passage71 communicates with the second passage72 through thecontrol valve58. Therefore, the high-pressure refrigerant gas in thedischarge chamber70 is discharged into theback pressure chamber49 through thefirst passage71, thecontrol valve58 and the second passage72. Since thethird passage73 is closed by thecontrol valve58 in this state, the refrigerant gas in theback pressure chamber49 is not discharged into thesuction chamber69. Consequently, the pressure in theback pressure chamber49 increases, and thevalve plate46 moves to the close position against the spring force of the urgingspring57 and force based on the pressure in thecommunication chamber48 so that the first and second valve holes61eand61fare closed.
• In a state where the first and second valve holes[0040]61eand61fare closed, thecompression chamber67 in the process of volume reduction does not communicate with thesuction chamber69. Also, thecompression chamber67 substantially completely compresses the refrigerant gas so that the displacement of thecompression mechanism12 becomes the maximum. For example, when the engine E is selected to drive thecompression mechanism12, thecompression mechanism12 performs the maximum displacement. Therefore, even though the rotational speed of therotary shaft13 is relatively small due to an idling state of the engine E, thecompression mechanism12 ensures a large amount of the discharged refrigerant gas per unit time, that is, thecompression mechanism12 performs relatively high cooling capacity.
• Also, as shown in FIG. 3A, when the[0041]solenoid58dis energized, the second passage72 communicates with thethird passage73 through thecontrol valve58. Therefore, the refrigerant gas in theback pressure chamber49 is discharged into thesuction chamber69 through the second passage72, thecontrol valve58 and thethird passage73. Since thefirst passage71 is closed by thecontrol valve58 in this state, the high-pressure refrigerant gas in thedischarge chamber70 is not discharged into theback pressure chamber49. Consequently, the pressure in theback pressure chamber49 falls, and thevalve plate46 moves to the open position by the spring force of the urgingspring57 and force based on the pressure in thecommunication chamber48 so that the first and second valve holes61eand61fare opened.
• In a state where the first and second valve holes[0042]61eand61fare opened, thecompression chamber67 in the process of volume reduction continuously communicates with thesuction chamber69 through any one of the first valve holes61eand through thecommunication chamber48 and thesecond valve hole61funtil thecompression chamber67 reduces in volume to the,.predetermined value. Therefore, thecompression chamber67 does not completely compress the refrigerant gas so that the displacement of thecompression mechanism12 is reduced from the maximum. For example, when theelectric motor21 is selected to drive thecompression mechanism12, the displacement of thecompression mechanism12 is reduced from the maximum. As the displacement of thecompression mechanism12 is reduced, torque required for driving thecompression mechanism12 becomes small. Therefore, the compressor C is downsized by reducing the size ofelectric motor21.
• In the present preferred embodiment, following advantageous effects are obtained.[0043]
• (1) The opening and closing of the by-[0044]pass passages48,61eand61f,that is, the variation of the displacement of the compressor C, is performed by contacting the front end surface46aof thevalve plate46 with thevalve seat surface48aand separating the front end surface46aof thevalve plate46 from thevalve seat surface48a.Therefore, in a state where thevalve plate46 is located at the close position, the contact of the front end surface46aof thevalve plate46 with thevalve seat surface48aseals the by-pass passages48,61eand61f.For example, in Japanese Unexamined Patent Publication No. 2001-32787, a valve portion (a column) of a spool opens and closes a port that is open at an inner circumferential surface of a cylinder (an inner surface of the cylinder). In comparison to this structure, closely contact between the front end surface46aof thevalve plate46 and thevalve seat surface48acan be easily enhanced without inhibiting mobility of thevalve plate46. Therefore, sealing the by-pass passages48,61eand61fin a state where thevalve plate46 is located at the close position can be ensured. Also, deterioration of performance of the compress C due to the leakage of the refrigerant gas from the by-pass passages48,61eand61fis suppressed.
• (2) The by-[0045]pass passages48,61eand61fare formed so as to continuously interconnect thecompression chamber67 with thesuction chamber69 until thecompression chamber67 in the process of volume reduction reduces in volume to the predetermined value in a state where thevalve plate46 is located at the open position. Namely, when thevalve plate46 is located at the open position, thecompression chamber67 does not completely compress until thecompression chamber67 reduces in volume to the predetermined value after1o the start of volume reduction. Accordingly, for example, in comparison to a variable displacement mechanism that changes the displacement of the compressor to a relatively small displacement by interconnecting a compression chamber with a suction pressure region after the compression chamber compresses until the compression chamber reduces in volume to a predetermined value, power loss of the compressor C caused due to re-compression for the refrigerant gas, that is, due to useless compression work, is suppressed.
• (3) The first valve holes[0046]61epartially constitute the by-pass passages48,61eand61fon an upstream side (a side of the compression chamber67). Thefirst valve hole61eis plurally provided. Each of the first valve holes61einterconnects thecompression chamber67 with thecommunication chamber48 at a position that is different from each other. The different portions of the front end surface46aof thevalve plate46 simultaneously opens and closes a plurality of the first valve holes61e.Therefore, the above described continuous communication between thecompression chamber67 in the process of volume reduction and thesuction chamber69 can be easily achieved without any complicated structure.
• Namely, for example, it is necessary to utilize a plurality of spool valves to open and close a plurality of valve holes due to interspersion of a plurality of the valve holes as disclosed in Japanese Unexamined Patent Publication No. 2001-32787. However, according to the[0047]valve plate46 utilized in the present preferred embodiment, simple structure, in which thevalve plate46 having a size in accordance with the interspersion of a plurality of the first valve holes61eis utilized, preferably deals with interspersion of a plurality of the first valve holes61e.
• (4) The[0048]valve plate46 simultaneously opens and closes thesecond valve61fthat partially constitutes the by-pass passages48,61eand61fon the side of thesuction chamber69 relative to thecommunication chamber48. Therefore, the first and second valve holes61eand61fare simultaneously, closed in a state where thevalve plate46 is located at the close position, and sealing the by-pass passages48,61eand61fcan be ensured further.
• (5) The[0049]valve plate46 is arranged along the fixedbase plate61 of the fixedscroll member41. Even though the compressor C includes the variable displacement mechanism, the compressor C is not lengthened in a direction of the axis L due to such arrangement of thevalve plate46. In, other word, by utilizing the valve plate46 (a plate-shaped body) as an open-close means for opening and closing the by-pass passages48,61eand61f,compact design to arrange the open-close means along the fixedbase plate61 of the fixedscroll member41 is achieved.
• Particularly, the compressor C is a hybrid compressor that is selectively driven by one of the power from the engine E through the[0050]power transmission mechanism22 arranged at thehousing11 and the power from theelectric motor21 installed in thehousing11. Therefore, the compressor C tends to be large-sized by including thepower transmission mechanism22 and theelectric motor21. When a compact variable displacement mechanism is utilized in the compressor C, increasing size of the compressor C is effectively suppressed.
• (6) The[0051]valve plate46 has an incomplete annular shape that is an annular shape of which a part is removed therefrom. Thedischarge hole61cis arranged at the center (the through hole) of thevalve plate46 for discharging the compressed refrigerant gas from thecompression chamber67 near the center of the fixedbase plate61 with thedischarge chamber70. As mentioned above, since thedischarge hole61 c is formed at the center of thevalve plate46 that is not utilized for opening and closing the first and second valve holes61eand61f,thecompression chamber67 near the center of the fixedbase plate61 can be interconnected with thedischarge chamber70 at a minimum distance. Therefore, the refrigerant gas can smoothly flow from thecompression chamber67 near the center of the fixedbase plate61 to thedischarge chamber70 so that the compressor C is prevented from deteriorating efficiency of the compressor C due to pressure loss based on conduit resistance between thecompression chamber67 anddischarge chamber70.
• (7) The[0052]rubber coat46bis provided at the front end surface46aof thevalve plate46 for sealing the by-pass passages48,61eand61fin a state where thevalve plate46 is located at the close position. Therefore, sealing the by-pass passages48,61 e and61fin a state where thevalve plate46 is located at the close position can be ensured further. Namely, thevalve plate46 is utilized as the open-close means for opening and closing the by-pass passages48,61eand61f,and the structure, in which the front end surface46aof thevalve plate46 contacts thevalve seat surface48aand is separated from thevalve seat surface48a,is utilized. Therefore, it is possible to arrange therubber coat46bfor improving the seal of the by-pass passages48,61eand61fin a state where thevalve plate46 is located at the close position without inhibiting the mobility of thevalve plate46.
• Following alternative embodiments may be practiced according to the present invention.[0053]
• In the above preferred embodiment, only the[0054]single valve plate46 is provided. Therefore, the displacement of the compressor C is switched only between the maximum displacement by locating thevalve plate46 at the close position and the minimum displacement by locating thevalve plate46 at the open position. Thevalve plate46 may be divided into a plurality of parts, and the displacement of the compressor C may be switched among more than three displacements.
• Namely, for example, the[0055]valve plate46 in the above preferred embodiment is divided into first and second parts. The first part of thevalve plate46 opens and closes a group of the first valve holes61ethat interconnect thesuction chamber69 with thecompression chamber67 in the process of volume reduction whose volume ranges from the maximum volume to a certain value (larger than the predetermined value). The second part of thevalve plate46 opens and closes another group of the first valve holes61ethat interconnect thesuction chamber69 with thecompression chamber67 in the process of volume reduction whose volume ranges from the certain value to the predetermined value. In this case, when the first and second parts of thevalve plate46 are located at the close position, the displacement of the compressor C becomes the maximum. When the first and second parts of thevalve plate46 are located at the open position, the displacement of the compressor C becomes the minimum. When the first and second parts of thevalve plate46 are respectively located at the open position and the close position, the displacement of the compressor C becomes an intermediate displacement between the maximum and the minimum.
• In the above preferred embodiment, the[0056]valve plate46 has an annular shape of which a part is removed therefrom so as to avoid thedischarge valve55 and the base of theretainer56 as shown in FIG. 2. However, when ashort discharge valve55 and ashort retainer56 are utilized and the bases of the discharge valve65 and theretainer56 are located closer to the center of the fixed scroll member41 (the side of thedischarge hole61c), thevalve plate46 may, be formed in a complete annular shape so as to surround thedischarge valve55 and theretainer56. In this case, the same advantageous effect is obtained as mentioned in paragraph (6) according to the above preferred embodiment.
• In the above preferred embodiment, the by-[0057]pass passages48,61eand61fare formed so as to continuously interconnect thecompression chamber67 with thesuction chamber69 until thecompression chamber67 in the process of volume reduction reduces in volume to the predetermined value in a state where thevalve plate46 is located at the open position. However, the by-pass passages48,61eand61fare not limited to the above preferred embodiment and may be formed so as to interconnect thecompression chamber67 with the suction pressure region after thecompression chamber67 has compressed to reduce in volume to a predetermined value. This manner reduces the number of the first valve holes61eand simplifies the structure of the by-pass passage.
• In the above preferred embodiment, the[0058]valve plate46 moves between the open position and the close position by regulating the pressure in theback pressure chamber49 by thecontrol valve58. Thevalve plate46 may be formed to move between the open position and the close position by directly actuating thevalve plate46 by an electromagnetic actuator.
• Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.[0059]

Claims (20)

What is claimed is:

1. A variable displacement mechanism in a scroll type compressor having a movable scroll member and a fixed scroll member, the movable scroll member and the fixed scroll member defining compression chambers therebetween, the compression chambers reducing in volume as the compression chambers are moved radially and inwardly by orbiting the movable scroll member relative to the fixed scroll member, whereby gas is compressed, a suction pressure region being defined in the scroll type compressor, the variable displacement mechanism comprising:

a by-pass passage provided for interconnecting the compression chamber in a process of volume reduction with the suction pressure region, the by-pass passage including a first valve hole;

a valve chamber provided for communicating with the first valve hole, the valve chamber forming a valve seat surface around an opening of the first valve hole;

a valve plate having an end surface that faces the valve seat surface, the valve plate being arranged in the valve chamber so as to selectively move between an open position, where the end surface is separated from the valve seat surface to open the first valve hole, and a close position, where the end surface contacts the valve, seat surface to close the first valve hole; and

an actuator actuating the valve plate.

2. The variable displacement mechanism according toclaim 1, wherein the by-pass passage is configured to continuously interconnect the compression chamber with the suction pressure region until the compression chamber in the process of volume reduction reduces in volume to a predetermined value in a state where the valve plate is located at the open position.

3. The variable displacement mechanism according toclaim 2, wherein the first valve hole partially constitutes the by-pass passage on a side of the compression chamber with respect to the valve chamber, the first valve hole being plurally provided, each of the first valve holes interconnecting the compression chamber with the valve chamber at a position that is different from each other, different portions of the end surface of the valve plate simultaneously opening and closing a plurality of the first valve holes.

4. The variable displacement mechanism according toclaim 3, wherein the valve plate simultaneously opens and closes a second valve hole that partially constitutes the by-pass passage on a side of the suction pressure region with respect to the valve chamber.

5. The variable displacement mechanism according toclaim 1, wherein the fixed scroll member includes a fixed base plate and a fixed spiral wall that extends from the fixed base plate, the valve chamber being defined on a side of a back surface of the fixed base plate, the valve seat surface of the valve chamber being formed by the fixed base plate, the valve plate being arranged along the fixed base plate.

6. The variable displacement mechanism according toclaim 5, wherein a discharge chamber is defined in the scroll type compressor, the valve plate having one of a complete annular shape and an incomplete annular shape that is an annular shape of which a part is removed therefrom, a discharge passage being formed at a center of the valve plate for discharging the compressed gas from the compression chamber to the discharge chamber.

7. The variable displacement mechanism according toclaim 1, wherein a seal member is arranged on one of the end surface of the valve plate and the valve seat surface for sealing the by-pass passage in a state where the valve plate is located at the close position.

8. The variable displacement mechanism according toclaim 1, wherein a discharge pressure region is defined in the scroll type compressor, the valve plate being arranged to divide the valve chamber into a communication chamber on the side of the first valve hole and a back pressure chamber on a side opposite to the side of the first valve hole, the communication chamber partially constituting the by-pass passage, the actuator including an urging spring that urges the valve plate toward the open position, a first control passage that interconnects the back pressure chamber with the discharge pressure region, and a control valve that regulates an opening degree of the first control passage based on an external command.

9. The variable displacement mechanism according toclaim 8, wherein the valve plate is located at the close position when the control valve opens the first control passage, the valve plate being located at the open position when the control valve closes the first control passage.

10. The variable displacement mechanism according toclaim 9, wherein the actuator also includes a second control passage that interconnects the suction pressure region with the back pressure chamber, the control valve regulating an opening degree of the second control passage based on the external command, the valve plate being located at the open position when the control valve opens the second control passage.

11. The variable displacement mechanism according toclaim 1, wherein the scroll type compressor is used for a vehicle air conditioner, the scroll type compressor being a hybrid type that is selectively driven by power from an engine for traveling a vehicle and by power from an internal electric motor.

12. A scroll type compressor that defines a suction pressure region comprising:

a movable scroll member;

a fixed scroll member, compression chambers being defined by the movable scroll member and the fixed scroll member, the compression chambers reducing in volume as the compression chambers are moved radially and inwardly by orbiting the movable scroll member relative to the fixed scroll member, whereby gas is compressed; and

a variable displacement mechanism including:

a by-pass passage provided for interconnecting the compression chamber with the suction pressure region, the by-pass passage including a first valve hole;

a valve chamber provided for communicating with the first valve hole, the valve chamber forming a valve seat surface around an opening of the first valve hole;

a valve plate having an end surface that faces the valve seat surface, the valve plate being arranged in the valve chamber so as to selectively move between an open position, where the end surface is separated from the valve seat surface to open the first valve hole, and a close position, where the end surface contacts the valve seat surface to close the first valve hole; and

an actuator actuating the valve plate.

13. The scroll type compressor according toclaim 12, wherein the by-pass passage is configured to continuously interconnect the compression chamber with the suction pressure region until the compression chamber in the process of volume reduction reduces in volume to a predetermined value in a state where the valve plate is located at the open position.

14. The scroll type compressor according toclaim 13, wherein the first valve hole partially constitutes the by-pass passage on a side of the compression chamber with respect to the valve chamber, the first valve hole being plurally provided, each of the first valve holes interconnecting the compression chamber with the valve chamber at a position that is different from each other, different portions of the end surface of the valve plate simultaneously opening and closing a plurality of the first valve holes.

15. The scroll type compressor according toclaim 14, wherein the valve plate simultaneously opens and closes a second valve hole that partially constitutes the by-pass passage on a side of the suction pressure region with respect to the valve chamber.

16. The scroll type compressor according toclaim 12, wherein the fixed scroll member includes a fixed base plate and a fixed spiral wall that extends from the fixed base plate, the valve chamber being defined on a side of a back surface of the fixed base plate, the valve seat surface of the valve chamber being formed by the fixed base plate, the valve plate being arranged along the fixed base plate.

17. The scroll type compressor according toclaim 16, wherein a discharge chamber is defined in the scroll type compressor, the valve plate having one of a complete annular shape and an incomplete annular shape that is an annular shape of which a part is removed therefrom, a discharge passage being formed at a center of the valve plate for discharging the compressed gas from the compression chamber to the discharge chamber.

18. The scroll type compressor according toclaim 12, wherein a seal member is arranged on one of the end surface of the valve plate and the valve seat surface for sealing the by-pass passage in a state where the valve plate is located at the close position.

19. The scroll type compressor according toclaim 12, wherein a discharge pressure region is defined in the scroll type compressor, the valve plate is arranged to divide the valve chamber into a communication chamber on the side of the first valve hole and a back pressure chamber on a side opposite to the side of the first valve hole, the communication chamber partially constituting the by-pass passage, the actuator including an urging spring that urges the valve plate toward the open position, a control passage that interconnects the back pressure chamber with the discharge pressure region, and a control valve that regulates an opening degree of the control passage based on an external command.

20. The scroll type compressor according toclaim 12, wherein the scroll type compressor is used for a vehicle air conditioner, the scroll type compressor being a hybrid type that is selectively driven by power from an engine for traveling a vehicle and by power from an internal electric motor.

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