EP0536989B1 - Slant plate type compressor with variable capacity control mechanism - Google Patents
Slant plate type compressor with variable capacity control mechanism Download PDFInfo
- Publication number
- EP0536989B1 EP0536989B1 EP92309128A EP92309128A EP0536989B1 EP 0536989 B1 EP0536989 B1 EP 0536989B1 EP 92309128 A EP92309128 A EP 92309128A EP 92309128 A EP92309128 A EP 92309128A EP 0536989 B1 EP0536989 B1 EP 0536989B1
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- EP
- European Patent Office
- Prior art keywords
- communication path
- control mechanism
- pressure
- compressor
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B27/00—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders
- F04B27/08—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders having cylinders coaxial with, or parallel or inclined to, main shaft axis
- F04B27/14—Control
- F04B27/16—Control of pumps with stationary cylinders
- F04B27/18—Control of pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block
- F04B27/1804—Controlled by crankcase pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B27/00—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders
- F04B27/08—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders having cylinders coaxial with, or parallel or inclined to, main shaft axis
- F04B27/14—Control
- F04B27/16—Control of pumps with stationary cylinders
- F04B27/18—Control of pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block
- F04B27/1804—Controlled by crankcase pressure
- F04B2027/1809—Controlled pressure
- F04B2027/1813—Crankcase pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B27/00—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders
- F04B27/08—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders having cylinders coaxial with, or parallel or inclined to, main shaft axis
- F04B27/14—Control
- F04B27/16—Control of pumps with stationary cylinders
- F04B27/18—Control of pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block
- F04B27/1804—Controlled by crankcase pressure
- F04B2027/1822—Valve-controlled fluid connection
- F04B2027/1831—Valve-controlled fluid connection between crankcase and suction chamber
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B27/00—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders
- F04B27/08—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders having cylinders coaxial with, or parallel or inclined to, main shaft axis
- F04B27/14—Control
- F04B27/16—Control of pumps with stationary cylinders
- F04B27/18—Control of pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block
- F04B27/1804—Controlled by crankcase pressure
- F04B2027/184—Valve controlling parameter
- F04B2027/1854—External parameters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B27/00—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders
- F04B27/08—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders having cylinders coaxial with, or parallel or inclined to, main shaft axis
- F04B27/14—Control
- F04B27/16—Control of pumps with stationary cylinders
- F04B27/18—Control of pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block
- F04B27/1804—Controlled by crankcase pressure
- F04B2027/184—Valve controlling parameter
- F04B2027/1859—Suction pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B27/00—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders
- F04B27/08—Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders having cylinders coaxial with, or parallel or inclined to, main shaft axis
- F04B27/14—Control
- F04B27/16—Control of pumps with stationary cylinders
- F04B27/18—Control of pumps with stationary cylinders by varying the relative positions of a swash plate and a cylinder block
- F04B27/1804—Controlled by crankcase pressure
- F04B2027/1886—Open (not controlling) fluid passage
- F04B2027/189—Open (not controlling) fluid passage between crankcase and discharge chamber
Description
- The present invention generally relates to a refrigerant compressor, and more particularly, to a slant plate type compressor, such as a wobble plate type compressor, with a variable displacement mechanism which is suitable for use in an automotive air conditioning system.
- A wobble plate type compressor with a variable displacement mechanism suitable for use in an automotive air conditioning system is disclosed in Japanese Utility Model Application Publication No. 64-27487. The compressor is driven by the engine of the automobile.
- The compressor includes a variable displacement mechanism which comprises a first communication path linking a crank chamber and a suction chamber in fluid communication, and a second communication path linking the crank chamber and a discharge chamber. A first valve control mechanism controlling the opening and closing of the first communication path is disposed within the first communication path. A second valve control mechanism controlling the opening and closing the second communication path is disposed within the second communication path. The first communication path is provided with a first valve seat formed at one portion thereof. The second communication path is provided with a second valve seat formed at one portion thereof. The first valve control mechanism includes a first valve member which is disposed so as to be received on and moved away from the first valve seat. The second valve control mechanism includes a second valve member which is disposed so as to be received on and moved away from the second valve seat.
- The first and second valve members are linked through a rod member so that when the first valve member is received on the first valve seat to close the first communication path, the second valve member is moved away from the second valve seat to open the second communication path. Conversely, when the first valve member is moved away from the first valve seat, the second valve member is received on the second valve seat.
- In operation of the compressor, the capacity of the compressor depends upon the crank chamber pressure relative to the suction chamber pressure, with the compressor operating at maximum capacity when the crank and suction chambers are linked in fluid communication. When the link between the crank and suction chambers is terminated, simultaneously linking the crank and discharge chambers, the pressure in the crank chamber increases relative to the suction chamber due to the flow of high pressure fluid from the discharge chamber to the crank chamber, reducing capacity. Of course, when operating at reduced capacity, the power demands of the compressor on the engine are reduced as well.
- The first valve control mechanism includes a pressure sensing device such as a diaphragm for sensing on one side the pressure in the suction chamber. The opposite side of the diaphragm is acted upon by a cylindrical member made of magnetic material and forming part of a solenoid mechanism. The relative position of the cylindrical member and thus the effective force provided thereby upon the diaphragm is controlled by the solenoid in response to an external vehicle condition, such as the power made upon the engine to drive the vehicle.
- The diaphragm is responsive to the net force acting on the opposite sides thereof and acts upon the rod member linking the first and second valve members to simultaneously control the opening and closing of the two communication paths. For a given positioning of the cylindrical member, the effect thereof on the diaphragm is constant, and the diaphragm responds to changes in the suction pressure to act upon the rod member to control the link between the crank and suction chambers. Thus, for a given positioning of the cylindrical member, the first valve member acts to maintain the suction pressure at a predetermined constant value. By changing the position of the cylindrical member through functioning of the solenoid in response to the demands made upon the engine for driving the vehicle, the predetermined constant value of the suction pressure can be changed in response to the demands made upon the engine.
- As discussed above, the compressor operates at maximum capacity when the crank and suction chambers are linked. This linkage occurs when the suction pressure exceeds the predetermined constant value and acts upon the diaphragm to move the first valve member away from the first valve seat, simultaneously isolating the crank and discharge chambers. For example, when the heat load on the evaporator is great, the suction pressure will be great, causing the crank and suction chambers to be linked, maximizing capacity.
- However, when first valve member acts to maintain the suction pressure at the predetermined constant value for the given positioning of the cylindrical member, the second valve member which is linked to the first valve member through the rod member continuously receives the discharge pressure of which value is varied by the unexpected changes in a heat exchanging capability of a condenser of the automotive air conditioning system caused by, such as the changes in velocity of the automobile. Therefore, the force downwardly acting on the rod member is unexpectedly varied in response to the changes in the discharge pressure so that the predetermined constant value in the auction chamber is undesirably changed even though an electric current having a constant amperage is supplied to the solenoid so as to induce the electromagnetic force having a constant amount. Accordingly, in this prior art, the suction pressure can not be stably maintained at the predetermined constant value during the control of communication between the crank and suction chambers.
- Furthermore, in this prior art, when the power demands for the vehicle is great, it is not desirable for the compressor to operate at maximum capacity, even if the heat load on the evaporator and the corresponding suction pressure are large. The solenoid acts in response to the greater demand for power made on the engine by the vehicle, to increase the effect of the cylindrical member upon the diaphragm, for example, by reducing the force with which the cylindrical member is pulled away from the diaphragm. Thus, the predetermined constant value at which the suction pressure is maintained will be increased, requiring an even greater pressure in the suction chamber before the crank and suction chambers will be linked.
- Therefore, even if the suction pressure is increased, for example, due to an increase of the heat load on the evaporator, the compressor will not function at maximum capacity while the demand for engine power by the vehicle is large, since the crank and suction chambers will be isolated. Correspondingly, the crank and discharge chambers will be linked, rapidly increasing the crank pressure relative to the suction pressure to minimize compressor capacity. Accordingly, the energy derived from the engine of the vehicle is effectively used for driving the vehicle. However, the pressure in the crank chamber may be increased to an excessively high value and maintained at that value until the crank and suction chambers are again linked, resulting in damage to the internal component parts of the compressor.
- In order to resolve this defect, a safety valve device disclosed in Japanese Utility Model Application Publication No. 62-72473 can be applied to the compressor. As described in the above Japanese Utility Model Application Publication, the safety valve device includes a ball member and a coil spring elastically supporting the ball member and is disposed in a third communication path which links one portion of the first communication path upstream of the suction pressure sensing device to another portion of the first communication path downstream of the suction pressure sensing device. The safety valve device opens and closes the third communication path in response to changes in the pressure differential between the crank chamber and the suction chamber. The third communication path is opened when the pressure differential between the crank chamber and the suction chamber exceeds a predetermined value which can avoid causing damage to the internal component parts of the compressor. Therefore, when communication between the crank chamber and the suction chamber is blocked while communication between the crank chamber and the discharge chamber is opened during operation of the variable displacement mechanism, thereby may causing an abnormal rise in the crank chamber pressure of conducting the refrigerant gas from the discharge chamber to the crank chamber, the third communication path is opened so as to forcibly and quickly reduce the crank chamber pressure and thereby prevent an abnormal pressure differential between the crank and suction chambers. As a result, excessive friction between the internal component ports of the compressor caused by the abnormal differential between the crank chamber and the suction chamber can be prevented.
- However, in this construction of the variable displacement mechanism, the third communication path is separate from the first and second communication paths such that the process of forming the third communication path and the process of disposing the safety valve device in the third communication path are additional steps required during the manufacturing of the compressor. Accordingly, the manufacturing process of the compressor is complicated by this requirement.
- Accordingly, it is an object of the present invention to provide a variable capacity slant plate type compressor in which pressure in a suction chamber is stably maintained at a desired value.
- It is another object of the present invention to provide a variable capacity slant type compressor in which the capacity of the compressor can be compulsorily quickly reduced without causing damage to the internal component parts of the compressor.
- The present invention relates to a slant plate type refrigerant compressor having a compressor housing enclosing a crank chamber, a suction chamber and a discharge chamber therein, said compressor housing comprising a cylinder block having a plurality of cylinders formed therethrough, a piston slidably fitted within each of said cylinders, drive means coupled to said pistons for reciprocating said pistons within said cylinders, said drive means including a drive shaft rotatably supported in said housing and coupling means for drivingly coupling said drive shaft to said pistons such that rotary motion of said drive shaft is converted into reciprocating motion of said pistons, said coupling means including a slant plate having a surface disposed at an adjustable inclined angle relative to a plane perpendicular to said drive shaft, the slant angle changing in response to a change in pressure in said crank chamber relative to pressure in said suction chamber to change the capacity of said compressor, a first communication path linking said crank chamber with said suction chamber, a first valve control mechanism disposed within said first communication path, said first valve control mechanism controlling communication of said first communication path in response to changes in pressure in said suction chamber, a second communication path linking said crank chamber with said discharge chamber, a second valve control mechanism disposed within said second communication path, said second valve control mechanism responding to an external signal and opening said second communication path to increase the pressure in said crank chamber to thereby reduce the capacity of the compressor. According to a first aspect of the invention, such a compressor is characterised by communication of said first communication path being continuously controlled by said first valve control mechanism so as to maintain pressure in said suction chamber at a predetermined constant value as long as said second communication path is closed, said second communication path being continuously opened as long as said first communication path is closed; and, according to a second aspect of the invention, is characterised by said first and second valve control mechanisms functioning independently of each other so as not to open said first and second communication paths simultaneously.
- In the accompanying drawings:
- Figure 1 illustrates a vertical longitudinal sectional view of a slant plate type refrigerant compressor including a capacity control mechanism according to one embodiment of this invention;
- Figure 2 illustrates a cross-sectional view taken on line 2-2 of Figure 1;
- Figure 3 illustrates an enlarged longitudinal sectional view of a valve control mechanism shown in Figure 1;
- Figures 4-6 illustrate a part of an assembling process of the valve control mechanism shown in Figure 3.
- Figure 7 illustrates an operational manner of a first and second valve members shown in Figure 3;
- Figure 8 illustrates a graph showing a relationship between a control point of a compressor suction chamber pressure and an amperage of an external electric current supplied to an electromagnetic coil of the valve control mechanism according to one embodiment of this invention.
- In Figures 1 and 2, for purpose of explanation only, the left side of the figures will be referenced as the forward end or front of the compressor, and the right side of the figures will be referenced as the rearward end or rear of the compressor.
- With reference to Figure 1, the construction of a slant plate the compressor, and more specifically a wobble plate
type refrigerant compressor 10, having a capacity control mechanism in accordance with one embodiment of the present invention is shown.Compressor 10 includescylindrical housing assembly 20 includingcylinder block 21,front end plate 23 disposed at one end ofcylinder block 21,crank chamber 22 enclosed withincylinder block 21 byfront end plate 23, andrear end plate 24 attached to the other end ofcylinder block 21.Front end plate 23 is mounted oncylinder block 21 forward ofcrank chamber 22 by a plurality ofbolts 101.Rear end plate 24 is also mounted oncylinder block 21 at the opposite end by a plurality of bolts (not shown). Valveplate 25 is located betweenrear end plate 24 andcylinder block 21.Opening 231 is centrally formed infront end plate 23 for supportingdrive shaft 26 by bearing 30 disposed therein. The inner end portion ofdrive shaft 26 is rotatably supported by bearing 31 disposed withincentral bore 210 ofcylinder block 21. Bore 210 extends to a rear end surface ofcylinder block 21. - Bore 210 includes
thread portion 211 formed at an inner peripheral surface of a central region thereof. Adjustingscrew 220 having a hexagonalcentral hole 221 is screwed intothread portion 211 ofbore 210. Circular disc-shaped spacer 230 havingcentral hole 231 is disposed between the inner end surface ofdrive shaft 26 and adjustingscrew 220. Axial movement of adjustingscrew 220 is transferred to driveshaft 26 through spacer 230 so that three elements move axially withinbore 210. The above mentioned construction and functional manner are described in detail in U.S. Patent No. 4,948,343 to Shimizu. -
Cam rotor 40 is fixed ondrive shaft 26 bypin member 261 and rotates withdrive shaft 26.Thrust needle bearing 32 is disposed between the inner end surface offront end plate 23 and the adjacent axial end surface ofcam rotor 40.Cam rotor 40 includesarm 41 havingpin member 42 extending therefrom.Slant plate 50 is disposedadjacent cam rotor 40 and includesopening 53. Driveshaft 26 is disposed throughopening 53.Slant plate 50 includesarm 51 havingslot 52.cam rotor 40 andslant plate 50 are connected bypin member 42, which is inserted inslot 52 to create a hinged joint.Pin member 42 is slidable withinslot 52 to allow adjustment of the angular position ofslant plate 50 with respect to a plane perpendicular to the longitudinal axis ofdrive shaft 26. Abalance weight ring 80 having a substantial mass is disposed on a nose ofhub 54 ofslant plate 50 in order to balance theslant plate 50 under dynamic operating conditions.Balance weight ring 80 is held in place by means of retainingring 81. -
Wobble plate 60 is nutatably mounted onhub 54 ofslant plate 50 throughbearings slant plate 50 to rotate with respect to wobbleplate 60. Fork-shapedslider 63 is attached to the radially outer peripheral end ofwobble plate 60 and is slidably mounted about slidingrail 64 disposed betweenfront end plate 23 andcylinder block 21. Fork-shapedslider 63 prevents the rotation ofwobble plate 60 such thatwobble plate 60 nutates alongrail 64 whencam rotor 40,slant plate 50 andbalance weight ring 80 rotate. Undesirable axial movement ofwobble plate 60 onhub 54 ofslant plate 50 is prevented by contact between a rear end surface of innerannular projection 65 ofwobble plate 60 and a front end surface ofbalance weight ring 80.Cylinder block 21 includes a plurality of peripherally locatedcylinder chambers 70 in whichpistons 71 are disposed. Eachpiston 71 is connected to wobbleplate 60 by a corresponding connectingrod 72. Accordingly, nutation ofwobble plate 60 thereby causespistons 71 to reciprocate within theirrespective chambers 71. -
Rear end plate 24 includes peripherally locatedannular suction chamber 241 and centrally locateddischarge chamber 251.Valve plate 25 includes a plurality ofvalved suction ports 242 linkingauction chamber 241 withrespective cylinders 70.Valve plate 25 also includes a plurality ofvalved discharge ports 252 linkingdischarge chamber 251 withrespective cylinders 70.Suction ports 242 anddischarge ports 252 are provided with suitable reed valves as described in U.S. Patent No. 4,011,029 to Shimizu. -
Suction chamber 241 includesinlet portion 241a which is connected to an evaporator (not shown) of the external cooling circuit.Discharge chamber 251 is provided withoutlet port 251a connected to a condenser (not shown) of the cooling circuit.Gaskets cylinder block 21 and the front surface ofvalve plate 25 and between the rear surface ofvalve plate 25 andrear end plate 24, respectively, to seat the mating surfaces ofcylinder block 21,valve plate 25 andrear end plate 24.Gaskets valve plate 25 thus formvalve plate assembly 200. Asteel valve retainer 253 is fixed on a central region of the rear surface ofvalve plate assembly 200 bybolt 254 and nut 255.Valve retainer 253 prevents excessive bend of the reed valve which is provided atdischarge port 252 during a compression stroke ofpiston 71. -
Conduit 18 axially bored throughcylinder block 21 so as to link crankchamber 22 to dischargechamber 251 throughhole 181 which is axially bored throughvalve plate assembly 200. A throttling device such asorifice tube 182, is fixedly disposed withinconduit 18.Filter member 183 is disposed inconduit 18 at the rear oforifice tube 182. Accordingly, a portion of the discharged refrigerant gas indischarge chamber 251 always flaws into crankchamber 22 with a reduced pressure generated byorifice tube 182. The above-mentioned construction and functional manner are described in detail in Japanese Patent Application Publication No. 1-142277. - With reference to Figure 2 additionally, radially extending
cylindrical cavity 243 is formed inrear end plate 24 along the approximate two-thirds of diameter ofrear end plate 24 so as to accommodatecapacity control mechanism 400 which is further discussed below. One end ofcylindrical cavity 243 is open to the external environment outside of the compressor, that is, to atmospheric conditions.Cylindrical cavity 243 includes first, second andthird portions 243a, 243b and 243c, respectively, which thereby from an axial outer end thereof. The diameter of second portion 243b is smaller than the diameter of first portion 243a, and is greater than the diameter ofthird portion 243c, Second portion 243b is linked tothird portion 243c throughtruncated cone portion 243d. First portion 243a ofcavity 243 is linked tosuction chamber 241 throughconduit 244 which is formed inrear end plate 24.Third portion 243c ofcavity 243 is linked to dischargechamber 251 throughconduit 245 which is formed inrear end plate 24. As illustrated in Figure 1,conduit 246 is formed inrear end plate 24 so as to link second portion 243b ofcavity 243 to hole 256 which is formed invalve plate assembly 200.Hole 256 is linked tocentral bore 210 through conduit 212 which is formed in the rear portion ofcylinder block 21. Central bore 210 is linked to crankchamber 22 throughconduit 262 formed in the inner end portion ofdrive shaft 26,hole 231 of spacer 230 andhole 221 of adjustingscrew 220. Accordingly, second portion 243b ofcavity 243 is linked to crankchamber 22 viaconduit 246,hole 256, conduit 212,central bore 210,hole 221,hole 231 andconduit 262. - With reference to Figure 3 in addition to Figure 2,
capacity control mechanism 400 includes a first annularcylindrical casing 410 of magnetic material accommodated in first portion 243a ofcavity 243 and a second annularcylindrical casing 420 having alarge diameter section 421 and asmall diameter section 422 which extends upwardly from a top end oflarge diameter section 421. First annularcylindrical casing 410 is fixedly disposed within first portion 243a ofcavity 243 by forcible insertion.Large diameter section 421 of second annularcylindrical casing 420 is fixedly disposed at a top end of first annularcylindrical casing 410. The top end ofsmall diameter section 422 of second annularcylindrical casing 420 terminates at an upper end region ofthird portion 243c ofcavity 243.Annular protrusion 423 is formed at an upper end region ofsmall diameter section 421 of second annularcylindrical casing 420, and is disposed in a lower end region ofthird portion 243c ofcavity 243. O-ring seal element 423a is disposed in an annular groove 423b formed at the outer peripheral surface ofannular protrusion 423 so as to seal the mating surfaces between the outer peripheral surface ofannular protrusion 423 and the inner peripheral surface ofthird portion 243c ofcavity 243. Thus,third portion 243c ofcavity 243 is sealingly insulated from second portion 243b ofcavity 243. - First
annular plate 411 is fixedly disposed at an upper inner region of first annularcylindrical casing 410, and includes an axialannular projection 412 which axially and downwardly extends from an inner peripheral end portion of firstannular plate 411. Axialannular projection 412 terminates at a point approximately half length of first annularcylindrical casing 410.Cylindrical pipe member 413, the length of which is a little less than the length of first annularcylindrical casing 410, is disposed in first annularcylindrical casing 410.Cylindrical pipe member 413 includes first and second annular flanges 413a and 413b formed at a top and bottom ends thereof, respectively. An upper end portion ofcylindrical pipe member 413 is fixedly surrounds axialannular projection 412.Annular disc plate 414 is fixedly disposed at a bottom end of first annularcylindrical casing 410 to define anannular cavity 415 formed in cooperation withcylindrical pipe member 413 and first annularcylindrical casing 410.Annular disc plate 414 includes an axialannular projection 414a which axially and downwardly extends from an inner peripheral end portion ofannular disc plate 414.Annular projection 414a includes thread portion 414b formed at an inner peripheral surface of a lower half region thereof. Adjusing screw 414c is screwed into thread portion 414b ofannular projection 414a. Annularelectromagnetic coil 430 is fixedly disposed withinannular cavity 415. Insulatingmaterial 431, such as for example, epoxy resin fixedly surrounds annularelectromagnetic coil 430. - A
vacant space 450 is defined bycylindrical pipe member 413, axialannular projection 414a and adjusting screw 414c.Cylindrical member 451 of magnetic material is slidably disposed in the axial direction invacant space 450. Firstcylindrical rod 460 slidably penetrates through axialannular projection 412. The bottom end position ofrod 460 is fixedly received in cylindrical hole 451a formed in the top end surface ofcylindrical member 451 through forcible insertion.First coil spring 470 is disposed between adjusting screw 414c andcylindrical member 451. A top end offirst coil spring 470 is in contact with the top end surface of cylindrical hole 451b which is formed at the bottom end surface ofcylindrical member 451. A bottom end offirst coil spring 470 is in contact with the bottom end surface ofcylindrical depression 414d which is formed at the top end surface of adjusting screw 414c. The restoring force offirst coil spring 470 urgescylindrical member 451 upwardly, thereby urgingrod 460 upwardly. The restoring force offirst coil spring 470 is adjusted by changing in the axial position of adjusting screw 414c. - When
electromagnetic coil 430 is energized, an electromagnetic force which tends to movecylindrical member 451 upwardly is induced. The magnitude of the electromagnetic force is directly proportional to the amperage of an electric current that is supplied toelectromagnetic coil 430 from an electric circuit (not shown). The electric circuit receives a signal representing the heat load on the evaporator, such as the temperature of air immediately before passing through the evaporator, and the signal representing the amount of demand for acceleration of the automobile, such as the magnitude of force stepping on the accelerator. After processing the two signals, an electric current is supplied from the electric circuit toelectromagnetic coil 430 in response to changes in the values of the two signals. The amperage of the electric current is continuously varied within the range from zero ampere to a predetermined maximum amperage, for example, 1.0 ampere. - More precisely, when the heat load on the evaporator is excessively large, such that the temperature of air immediately before passing through the evaporator is excessively high, and when the amount of demand for acceleration of the automobile is small, an electric current having zero ampere, i.e., no electric current, is supplied from the electric circuit to the
electromagnetic coil 430 after the processing of the two signals through the electric current. However, when the amount of demand for acceleration of the automobile exceeds a predetermined value, the signal representing the demand for acceleration overrides the signal representing the heat load on the evaporator in the processing of the two signals by the electric circuit. As a result, an electric current having the predetermined maximum amperage is supplied from the electric circuit to theelectromagnetic coil 430 even though the heat load on the evaporator is excessively large. Furthermore, when the heat load on the evaporator is excessively small, such as when the temperature of air immediately before passing through the evaporator is excessively low, an electric current having the predetermined maximum amperage is supplied from the electric circuit to theelectromagnetic coil 430 without regard to the amount of demand for acceleration of the automobile. - O-
ring seal element 416 is disposed inannular groove 417 formed in the outer peripheral surface of the bottom end portion of first annularcylindrical casing 410, to thereby seal the mating surfaces between the outer peripheral surface of first annularcylindrical casing 410 and the inner peripheral surface of first portion 243a ofcavity 243. Thus, first portion 243a ofcavity 243 is sealingly insulated from the ambient atmosphere outside of the compressor. -
First valve member 480 is disposed in cylindricalhollow space 421a oflarge diameter section 421 of second annularcylindrical casing 420.Axial hole 480a is centrally formed invalve member 480 so as to slidably dispose secondcylindrical rod 481 therethrough. Secondannular plate 482 is fixedly disposed at a bottom end portion of cylindricalhollow space 421a oflarge diameter section 421 of second annularcylindrical casing 420 by forcible insertion.Axial hole 482a is centrally formed inannular plate 482 so as to slidably dispose a lower end portion of secondcylindrical rod 481.Diaphragm 483 is disposed between the bottom end surface of secondcylindrical rod 481 and the top end surface ofcircular disc plate 484 which is disposed on a top end surface of firstcylindrical rod 460. An outer peripheral portion ofdiaphragm 483 is fixedly disposed between the bottom end surface oflarge diameter section 421 of second annularcylindrical casing 420 and the top end surface of thirdannular plate 485 which is sandwiched by firstannular plate 411 and the bottom end oflarge diameter section 421 of second annularcylindrical casing 420. The top end portion of firstcylindrical rod 460 slidably penetrates through thirdannular plate 485.Indent 485a is formed at the top end surface of thirdannular plate 485 so that annular ridge 485b is formed at an inner peripheral surface of thirdannular plate 485 so as to receivecircular disc plate 484 disposed on the top end surface of firstcylindrical rod 460. - O-
ring seal element 486 is elastically disposed within annular cylindricalhollow space 487, which is defined by first and thirdannular plates large diameter section 421 of second annularcylindrical casing 421 and first annularcylindrical casing 410, so that an invasion of the ambient atmosphere outside of the compressor into first portion 243a ofcavity 243 and cylindricalhollow space 421a oflarge diameter section 421 of second annularcylindrical casing 420 abovediaphragm 483 is prevented. - Annular disc plate 488 is fitly disposed in an
annular groove 481c (shown in Figures 4-6) formed at an outer peripheral surface of secondcylindrical rod 481 at a position above secondannular plate 482.Second coil spring 489 surrounding secondcylindrical rod 481 is resiliently disposed between a top end surface of annular disc plate 488 and a bottom surface ofannular depression 480b which is formed at a bottom end surface offirst valve member 480. The restoring force ofsecond coil spring 489 urgesfirst valve member 480 upwardly. -
Small diameter section 422 of second annularcylindrical casing 420 includes cylindricalhollow space 422a having first, second andthird regions second region 422c so thatannular ridge 422e is formed at a position which is a boundary between first andsecond regions 422b and 422c. A diameter ofthird region 422d is greater than the diameter ofsecond region 422c so that annular ridge 422f is formed at a position which is a boundary between second andthird regions - First region 422b of cylindrical
hollow space 422a is linked to the top end of cylindricalhollow space 421a at its bottom end. A diameter of cylindricalhollow space 421a is greater than the diameter of first region 422b of cylindricalhollow space 422a so thatannular ridge 424 is formed at a position which is a boundary between cylindricalhollow space 421a and first region 422b of cylindricalhollow space 422a.Annular ridge 424 functions as a first valve seat so as to receivefirst valve member 480. An upper end portion of secondcylindrical rod 481 is slidably disposed in the axial direction within first region 422b of cylindricalhollow space 422a.Third coil spring 490 surrounding the upper end portion of secondcylindrical rod 481 is resiliently disposed between the top end surface offirst valve member 480 and the side wall ofannular ridge 422e. The restoring force ofthird coil spring 490 urgesfirst valve member 480 downwardly. - Second
cylindrical rod 481 includesannular ridge 481b formed at an outer peripheral surface thereof so as to receive the top end surface of an inner peripheral portion offirst valve member 480. Secondcylindrical rod 481 further includesaxial hole 481a formed at the top end surface thereof. A bottom end portion of thirdcylindrical rod 491 is forcibly inserted intoaxial hole 481a so that second and thirdcylindrical rods - Third
cylindrical rod 491 includeslarge diameter section 491a, small diameter section 491b andtruncated cone section 491c which connects a top end oflarge diameter section 491a to a bottom end of small diameter section 491b. An upper half portion oflarge diameter section 491a of thirdcylindrical rod 491 is fitly slidably disposed in a lower half portion ofsecond region 422c of cylindricalhollow space 422a. Small diameter section 491b of thirdcylindrical rod 491 is disposed in an upper half portion ofsecond region 422c of cylindricalhollow space 422a so as to defineradial air gap 422g between the outer peripheral surface of small diameter section 491b of thirdcylindrical rod 491 and the inner peripheral surface of the upper half portion ofsecond region 422c of cylindricalhollow space 422a. A top end surface of thirdcylindrical rod 491 in located near annular ridge 422f, and moves into or away fromthird region 422d of cylindricalhollow space 422a in response to changes in an operational condition ofcapacity control mechanism 400. - A
ball element 492 as a second valve member is loosely disposed withinthird region 422d of cylindricalhollow space 422a.Circular disc plate 493 is fixedly disposed at a top end ofsmall diameter section 422 of second annularcylindrical casing 420.Axial hole 493a is centrally formed throughcircular disc plate 493 so as to linkthird portion 243c ofcavity 243 tothird region 422d of cylindricalhollow space 422a. Axial projection 493b axially downwardly projecting from an inner peripheral end ofaxial hole 493a is formed at a bottom end surface ofcircular disc plate 493.Fourth coil spring 494 surrounding axial projection 493b is resiliently disposed between the bottom end surface ofcircular disc plate 493 and the upper spherical surface ofball element 492. The restoring force offourth coil spring 494 urgesball element 492 downwardly. Annular ridge 422f functions as a second valve seat so as to receiveball element 492. - O-
ring seal element 425 is disposed in anannular groove 426 formed at the outer peripheral surface oflarge diameter section 421 of second annularcylindrical casing 420 so as to seal the mating surfaces between the outer peripheral surface oflarge diameter section 421 of second annularcylindrical casing 420 and the inner peripheral surface of second portion 243b ofcavity 243. Thus, second portion 243b ofcavity 243 is sealingly insulated from first portion 243a ofcavity 243. - A plurality of first
radial holes 427 are formed at a side wall oflarge diameter section 421 of second annularcylindrical casing 420 so as to link first portion 243a ofcavity 243 to cylindricalhollow space 421a oflarge diameter section 421 of second annularcylindrical casing 420. Therefore, a fluid communication betweensuction chamber 241 with cylindricalhollow space 421a oflarge diameter section 421 of second annularcylindrical casing 420 is obtained byconduit 244, first portion 243a ofcavity 243 andradial holes 427. - A plurality of second
radial holes 428 are formed at a side wall of a lower end portion ofsmall diameter section 422 of second annularcylindrical casing 420 so as to link second portion 243b ofcavity 243 to first region 422b of cylindricalhollow space 422a ofsmall diameter section 422 of second annularcylindrical casing 420. Therefore, a fluid communication between crankchamber 22 with first region 422b of cylindricalhollow space 422a ofsmall diameter section 422 of second annularcylindrical casing 420 is obtained byconduit 262,hole 231,hole 221,central bore 210, conduit 212,hole 256,conduit 246, second portion 243b ofcavity 243 andradial holes 428. - A plurality of third
radial holes 429 are formed at a side wall ofsmall diameter section 422 of second annularcylindrical casing 420 at a position betweenradial holes 428 and O-ring seal element 423a so as to link second portion 243b ofcavity 243 toradial air gap 422g. Therefore, a fluid communication between crankchamber 22 with annular cylindricalhollow space 422g is obtained byconduit 262,hole 231,hole 221,central bore 210, conduit 212,hole 256,conduit 246, second portion 243b ofcavity 243 andradial holes 429. - Furthermore,
third region 422d of cylindricalhollow space 422a ofsmall diameter section 422 of second annularcylindrical casing 420 communicates withdischarge chamber 251 viaconduit 245,third portion 243c ofcavity 243 andhole 493a ofcircular disc plate 493. - In the above-mentioned construction of
capacity control mechanism 400, second and third coil springs 489 and 490 are selected so as to continuously contact the top end surface offirst valve member 480 to a side wall ofannular ridge 481b untilfirst valve member 480 is received onannular ridge 424. As long as the top end surface offirst valve member 480 is in contact with the side wall ofannular ridge 481b, secondcylindrical rod 481,first valve member 480,second coil spring 489 and annular disc plate 488 are regarded as a substantial one body. Therefore, the top end surface of the central region ofdiaphragm 483 is maintained in contact with the bottom end surface of secondcylindrical rod 481 by virtue of the restoring force ofthird coil spring 490 untilfirst valve member 480 is received onannular ridge 424. Similarly, the bottom end surface of the central region ofdiaphragm 483 is maintained in contact with the top end surface ofcircular disc plate 484 by virtue of the restoring force offirst coil spring 470. -
Indent 485a is formed at the top end surface of thirdannular plate 485 such thatindent 485a faces the bottom end surface ofdiaphragm 483.Indent 485a is linked to the ambient atmosphere outside of the compressor via the gap 412a created betweenrod 460 andannular projection 412,vacant space 450, and the gap 414e created between axialannular projection 414a and adjusting screw 414c. Thus, the bottom end surface ofdiaphragm 483 in in contact with and thereby receives air at atmospheric pressure. - Similarly, cylindrical
hollow space 421a of thelarge diameter section 421 of second annularcylindrical casing 420 is linked tosuction chamber 241 viaradial holes 427, first portion 243a ofcavity 243, andconduit 244. thus, the top end surface ofdiaphragm 483 is in contact with and thereby receives the refrigerant at the suction chamber pressure through a plurality of axial holes 482b axially formed through a peripheral portion ofannular plate 482. - With reference to Figures 4-6, a part of the assembling process of
capacity control mechanism 400 is described bellow. - With reference to Figure 4, second and third
cylindrical rods cylindrical rod 491 intoaxial hole 481a of secondcylindrical rod 481 by forcible insertion.First valve member 480 on whichsecond coil spring 489 is disposed is slidably about secondcylindrical rod 481. With the above construction, in an initial step of the part of the assembling process of capacity control mechanism, thirdcylindrical rod 491 is slidably inserted intosecond region 422c of cylindricalhollow space 422a from the lower side ofsecond region 422c of cylindricalhollow space 422a so as to sufficiently project small diameter section 491b of thirdcylindrical rod 491 intothird region 422d of cylindricalhollow space 422a. - With reference to figure 5, in a next step of the part of the assembling process of
capacity control mechanism 400, the bottom end surface offirst valve member 480 is pushed upwardly by inserting annularcylindrical member 500 into cylindricalhollow space 421a with simultaneously projecting secondcylindrical rod 481 into innerhollow space 501 of annularcylindrical member 500 untilfirst valve member 480 is received onannular ridge 424. In tills step, small diameter section 491b of thirdcylindrical rod 491 is further projected intothird region 422d of cylindricalhollow space 422a. In addition, the top end surface offirst valve member 480 is not in contact with the side wall ofannular ridge 481b whenfirst valve member 480 is received onannular ridge 424. - With reference to Figure 6, in a final step of the part of the assembling process of
capacity control mechanism 400, the top end surface of small diameter section 491b of thirdcylindrical rod 491 is pushed downwardly throughball element 492 by insertingcylindrical member 600 intothird region 422d of cylindricalhollow space 422a untilball element 492 is received on annular ridge 422f whilefirst valve member 480 is upwardly urged by annularcylindrical member 500 with maintaining a contact betweenfirst valve member 480 andannular ridge 424. In this step, the bottom end portion of thirdcylindrical rod 491 is further forcibly inserted intoaxial hole 481a of secondcylindrical rod 481. In addition, the top end surface offirst valve member 480 is in contact with the side wall ofannular ridge 481b whenball element 492 is received on annular ridge 422f. - According to the above-mentioned part of the assembling process of
capacity control mechanism 400,capacity control mechanism 400 is constructed so as to performfirst valve member 480 andball element 492 as follows during operation ofcapacity control mechanism 400. With reference to Figure 7, when secondcylindrical rod 481 is located at the position "B", bothfirst valve member 480 andball element 492 are received onannular ridges 424 and 422f, respectively. When secondcylindrical rod 481 is located below the position "B",first valve member 480 continuously moves away fromannular ridge 424 with the various opening amounts whileball element 491 is continuously received on annular ridge 422f. When secondcylindrical rod 481 is located above the position "B",first valve member 480 is continuously received onannular ridge 424 whileball element 492 continuously moves away from annular ridge 422f with the various opening amounts. - During operation of
compressor 10,drive shaft 26 is rotated by the engine of the automobile throughelectromagnetic clutch 300.Cam rotor 40 is rotated withdrive shaft 26, thereby rotatingslant plate 50 as well, which in turn causes wobbleplate 60 to nutate. The nutational motion ofwobble plate 60 then reciprocatespistons 71 out of phase in theirrespective cylinders 70. Aspistons 71 are reciprocated, refrigerant gas is introduced intosuction chamber 241 throughinlet portion 241a, flows into eachcylinder 70 throughsuction ports 242, and is then compressed. The compressed refrigerant gas is then discharged to dischargechamber 251 from eachcylinder 70 throughdischarge ports 252, and continues therefrom into the cooling circuit throughoutlet portion 251a. - The capacity of
compressor 10 is adjusted in order to maintain a constant pressure insuction chamber 241, irrespective of the changes in the heat load on the evaporator or the rotating speed of the compressor. The capacity of the compressor is adjusted by changing the angle of the slant plate, which is dependent upon the crank chamber pressure, or more precisely, which is dependent upon the differential between the crank chamber and the suction chamber pressures. During the operation ofcompressor 10, the pressure of the crank chamber increases due to blow-by gas flowingpast pistons 71 as they reciprocate incylinders 70. As the crank chamber pressure increases relative to the suction chamber pressure, the slant angle ofslant plate 50 as well as the slant angle ofwobble plate 60 decreases, thereby decreasing the capacity of the compressor. Likewise, a decrease in the crank chamber pressure relative to the suction chamber pressure causes an increases in the angle ofslant plate 50 andwobble plate 60, and thus an increase in the capacity of the compressor. - The operation of
capacity control mechanism 400 ofcompressor 10 in accordance with one embodiment of the present invention is carried out in the following manner. - With reference to Figures 1,3, 7 and 8, when the suction chamber pressure is controlled to be maintained at, for example, 2.0 kg/cm² G by continuously supplying an electric current having 0.5 A from the electric circuit to the
electromagnetic coil 430, secondcylindrical rod 481 upwardly and downwardly moves frequently with a slight amount at slightly below the position "B" in response to the slight changes in the heat load on the evaporator, i.e., the slight changes in the suction chamber pressure which acts on the top end surface ofdiaphragm 483 whileball element 492 is continuously received on annular ridge 422f so as to continuously block in fluid communication between the crank anddischarge chambers first valve member 480 continuously moves away fromannular ridge 424 with frequently and slightly changing its opening amount whileball element 492 is continuously received on annular ridge 422f so as to continuously block in fluid communication between the crank anddischarge chambers first valve member 480. - At the above-mentioned compressor operational stage, when the demand for acceleration of the automobile exceeds the predetermined value, an electric current having the predetermined maximum amperage, i.e., 1.0 A is supplied from the electric circuit to
electromagnetic coil 430. Therefore, the amperage of the electric current supplied from the electric circuit toelectromagnetic coil 430 is suddenly increased from 0.5 A to 1.0 A with a large amount. Accordingly, the electromagnetic force which tends to move firstcylindrical rod 460 upwardly is also increased with a large amount so that the upward force acting ondiaphragm 483 excessively overcomes the downward force acting ondiaphragm 483. Therefore, second and thirdcylindrical rods first valve member 480 is received onannular ridge 424 with maintaining the contact between the top end surface offirst valve member 480 and the side wall ofannular ridge 481b. Furthermore, as soon as the side wall ofannular ridge 481b begins to move away from the top end surface offirst valve member 480 whilefirst valve member 480 is received onannular ridge 424, the restoring force ofthird coil spring 490 downwardly acting ondiaphragm 483 becomes ineffectual while the restoring force ofsecond coil spring 489 also downwardly acting ondiaphragm 483 becomes effectual. - At the time immediately after
first valve member 480 is received onannular ridge 424, the crank chamber pressure slightly increases due to the block in fluid communication between crank andsuction chambers slant plate 50 andwobble plate 60 with respect to the plane perpendicular to the longitudinal axis ofdrive shaft 26 to the smaller side. Therefore, the slant angle ofslant plate 50 andwobble plate 60 is still maintained at the position at the time immediately beforefirst valve member 480 is received onannular ridge 424 so that the suction chamber pressure is still maintained at the value at the time immediately beforefirst valve member 480 is received onannular ridge 424. - Accordingly, the resultant of the atmospheric pressure force upwardly acting on
diaphragm 483, the restoring force offirst coil spring 470 and the electromagnetic force induced byelectromagnetic coil 430 overcomes the resultant of the suction chamber pressure force downwardly acting ondiaphragm 483, the restoring force ofsecond coil spring 489, the restoring force offourth coil spring 494 and the discharge chamber pressure force downwardly acting on the effective pressure receiving surface ofball element 492. As a result, second and thirdcylindrical rods annular ridge 481b from the top end surface offirst valve member 480 whitefirst valve member 480 in received onannular ridge 424. That is, secondcylindrical rod 481 moves upwardly so as to locate at a position which is higher than position "B". Therefore,ball element 492 moves away from annular ridge 422f so as to communicate the fluid communication between discharge and crankchambers first valve member 480 is received onannular ridge 424 so as to block in fluid communication between crank andsuction chambers - Accordingly, a large amount of the refrigerant gas in
discharge chamber 251 instantly flows into crankchamber 22 so that the crank chamber pressure is instantly increased with a large amount, thereby instantly decreasing the slant angle ofslant plate 50 andwobble plate 60 to the minimum value; and therefore,compressor 10 operates at a minimum capacity displacement. This effectively reduces the energy consumption by the compressor, the driving force which derived from the automobile engine, and thereby effectively assists in providing the acceleration that is demand. - With the lapse of time of operation of
compressor 10 with the minimum capacity displacement, the suction chamber pressure gradually increases and thereby the resultant downwardly acting ondiaphragm 483 gradually increases relative to the resultant upwardly acting ondiaphragm 483; and accordingly, second and thirdcylindrical rods ball element 492 as well. When the suction chamber pressure rises at 4.0 kg/cm² G,ball element 492 is received on annular ridge 422f so as to block in fluid communication between crank anddischarge chambers first valve member 480 by continuously supplying an electric currant having 1.0 A from the electric circuit to theelectromagnetic coil 430. - In the above-mentioned compressor operational stage, when the resultant of the crank chamber pressure force downwardly acting on the top end effective pressure receiving surface of
first valve member 480 and the restoring force ofthird coil spring 490 exceeds the resultant of the suction chamber pressure force upwardly acting on the bottom end effective pressure receiving surface offirst valve member 480 and the restoring force ofsecond coil spring 489,first valve member 480 downwardly moves with fitly sliding along secondcylindrical rod 481 so as to create an annular air gap betweenfirst valve member 480 andannular ridge 424 so that the refrigerant gas incrank chamber 22 can flow intosuction chamber 241 past the above annular air gap. Accordingly, the expressive pressure differential between thecrank chamber 22 end thesuction chamber 241 due to the excessive conduction of the refrigerant gas fromdischarge chamber 251 to crankchamber 22, and thereby generating a force excessively urgingwobble plate 60 rearwardly is effectively eliminated. Therefore, the excessive rearward movement ofwobble plate 60, and thereby results in excessive friction between the rear end surface ofannular projection 65 ofwobble plate 60 and the rear end surface ofdrive shaft 26 and a front end surface of spacer 230 disposed incentral bore 210 can be effectively prevented. Accordingly,first valve member 480 further functions as a safety valve device whenball element 492 moves away from annular ridge 422f. Therefore, it is not required to form an additional passageway within which the safety valve device is disposed. - Furthermore, at any time when an amperage of an electric current is changed to the smaller value side at a situation where the suction chamber pressure is continuously controlled at any constant value, the resultant downwardly acting on
diaphragm 483 is always changed to be superior to the resultant upwardly acting ondiaphragm 483 so thatball element 492 is always maintained to be received on annular ridge 422f so as to block in fluid communication between crank anddischarge chambers - As described above, at only time when an amperage of an electric current is changed to the greater value side at a situation where the suction chamber pressure is continuously controlled at any constant value, the resultant upwardly acting on
diaphragm 483 is changed to be superior to the resultant downwardly acting ondiaphragm 483 so thatball element 492 moves away from annular ridge 422f so as to communicate in fluid communication between crank anddischarge chambers ball element 492 only performs to communicate in fluid communication between crank anddischarge chambers - Furthermore, since
first valve member 480 andball element 492 do not simultaneously move away from the respectiveannular ridge 424 and 422f, a path linking crankchamber 22 and second portion 243b ofcylindrical cavity 243 forms a part of both the path linking crank anddischarge chambers suction chambers - Moreover, in the embodiment of the present invention,
diaphragm 483 is used as a pressure sensing device for sensing pressure insuction chamber 241, however, other pressure sensing devices, such as a bellows may be used in the present invention.
Claims (5)
- A slant plate type refrigerant compressor having a compressor housing enclosing a crank chamber, a suction chamber and a discharge chamber therein, said compressor housing comprising a cylinder block having a plurality of cylinders formed therethrough, a piston slidably fitted within each of said cylinders, drive means coupled to said pistons for reciprocating said pistons within said cylinders, said drive means including a drive shaft rotatably supported in said housing and coupling means for drivingly coupling said drive shaft to said pistons such that rotary motion of said drive shaft is converted into reciprocating motion of said pistons, said coupling means including a slant plate having a surface disposed at an adjustable inclined angle relative to a plane perpendicular to said drive shaft, the slant angle changing in response to a change in pressure in said crank chamber relative to pressure in said suction chamber to change the capacity of said compressor, a first communication path linking said crank chamber with said suction chamber, a first valve control mechanism disposed within said first communication path, said first valve control mechanism controlling communication of said first communication path in response to changes in pressure in said suction chamber, a second communication path linking said crank chamber with said discharge chamber, a second valve control mechanism disposed within said second communication path, said second valve control mechanism responding to an external signal and opening said second communication path to increase the pressure in said crank chamber to thereby reduce the capacity of the compressor, characterised by
communication of said first communication path being continuously controlled by said first valve control mechanism so as to maintain pressure in said suction chamber at a predetermined constant value as long as said second communication path is closed, said second communication path being continuously opened as long as said first communication path is closed. - The slant plate type refrigerant compressor of claim 1, said first valve control mechanism including a first valve member, said first communication path including a first valve seat formed at one portion thereof, said second valve control mechanism including a second valve member, said second communication path including a second valve seat formed at one portion thereof, communication of said first communication path being continuously controlled by said first valve control mechanism so as to maintain pressure in said suction chamber at a predetermined constant value as long as said second valve member is received on said second valve seat, said second valve member continuously moving away from said second valve seat as long as said first valve member is received on said first valve seat.
- The slant plate type refrigerant compressor of claim 1 wherein said first communication path is forcibly opened when the pressure difference between the crank chamber and the suction chamber exceeds a predetermined value.
- The slant plate type refrigerant compressor of claim 2 wherein said first valve member is forcibly moved away from said first valve seat so as to open said first communication path when the pressure difference between the crank chamber and the suction chamber exceeds a predetermined value.
- A slant plate type refrigerant compressor having a compressor housing enclosing a crank chamber, a suction chamber and a discharge chamber therein, said compressor housing comprising a cylinder block having a plurality of cylinders formed therethrough, a piston slidably fitted within each of said cylinders, drive means coupled to said pistons for reciprocating said pistons within acid cylinders, said drive means including a drive shaft rotatably supported in said housing and coupling means for drivingly coupling said drive shaft to said pistons such that rotary motion of said drive shaft is converted into reciprocating motion of said pistons, said coupling means including a slant plate having a surface disposed at an adjustable inclined angle relative to a plane perpendicular to said drive shaft, the slant angle changing in response to a change in pressure in said crank chamber relative to pressure in said suction chamber to change the capacity of said compressor, a first communication path linking said crank chamber with said suction chamber, a first valve control mechanism disposed within said first communication path, said first valve control mechanism controlling communication of said first communication path in response to changes in pressure in said suction chamber, a second communication path linking said crank chamber with said discharge chamber, a second valve control mechanism disposed within said second communication path, said second valve control mechanism responding to an external signal and opening said second communication path to increase the pressure in said crank chamber to thereby reduce the capacity of the compressor, characterised by
said first and second valve control mechanism functioning independently of each other so an not to open said first and second communication paths simultaneously.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP81339/91 | 1991-10-07 | ||
JP8133991 | 1991-10-07 | ||
JP3275824A JPH0599136A (en) | 1991-10-23 | 1991-10-23 | Variable capacity type swash plate type compressor |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0536989A1 EP0536989A1 (en) | 1993-04-14 |
EP0536989B1 true EP0536989B1 (en) | 1995-05-03 |
Family
ID=26422363
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP92309128A Expired - Lifetime EP0536989B1 (en) | 1991-10-07 | 1992-10-07 | Slant plate type compressor with variable capacity control mechanism |
Country Status (2)
Country | Link |
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US (1) | USRE35672E (en) |
EP (1) | EP0536989B1 (en) |
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DE10115506B4 (en) * | 2000-04-04 | 2006-02-09 | Sanden Corp., Isesaki | Piston compressor variable displacement |
Also Published As
Publication number | Publication date |
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USRE35672E (en) | 1997-11-25 |
EP0536989A1 (en) | 1993-04-14 |
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