COMPRESSOR

Abstract: A compressor (K1, K2, K3, K4) including a fixed member (11, 40, 42) formed with a plurality of suction ports (15, 17) and a discharge port (22) for refrigerant, a movable member (12, 14) movable relative to the fixed member (11, 40, 42), a valve (25, 66) provided with a member (54) made of shape memory alloy, and a power source (68) for supplying electric power to the member (54) such that the valve (25, 66) opens or closes one (17) of the suction ports (15, 17) upon expansion or contraction of the member (54).

Description: COMPRESSOR BACKGROUND OF THE INVENTION The present invention generally relates to compressors and more particularly to, a variable output type rotary compressor for use in an air conditioner and the like. A recent trend toward saving of energy increases demand for compressors of higher efficiency for use in refrigerating cycles. Xnown compressors for use in air conditioners of motor vehicles have such inconveniences that since the compressors are forcedly driven synchronously with the number of revolutions of engines of the motor vehicles at the time of high-speed running of the motor vehicles, refrigerating capability of the air conditioners increases excessively beyond a proper level and that heat load conditions of heat exchangers of the air conditioners vary drastically due to environmental conditions, running conditions, etc. of the motor vehicles. In order to obviate the above described drawbacks of the prior art air conditioners of the motor vehicles and maintain the refrigerating capability of the air conditioners at the proper level at all times, such a method has been conventionally proposed that a displacement of the compressors is arbitrarily adjusted from an outside of the compressors. In Fig. 1, there is shown a prior art variable output type compressor in which a discharge valve 204 provided in a Cylinder formed with a cylinder chamber 203 is released away from the cylinder by a solenoid valve including a solenoid 200 such that compression of high-pressure gas 206 is stopped. Namely, when the solenoid valve is lowered so as to close a front passage of the high-pressure gas 206, so that pressure for depressing a plunger 201 in the leftward direction in Fig. 1 decreases and thu, the plunger 201 is pushed in the rightward direction in Fig. 1 by an urging force of a spring 202. As a result, since the discharge valve 204 fixedly attached to the plunger 201 is released away from the cylinder, it becomes impossible to compress the high-pressure gas 206. The known compressor of Fig. 1 has such a disadvantage that since it becomes necessary to secure a sufficiently large space for the solenoid 200, the compressor becomes large in size and weight and complicated in structure. Furthermore, the prior art compressor of Fig. 1 has been disadvantageous in that it is difficult to select material for stably bonding adjacent ones of turns of the winding wire of the solenoid 200 to one another since the solenoid 200 is heated at high temperature and under high pressure and that manufacture of the solenoid 200 is difficult, thereby resulting in high production cost of the compressor. SUMMARY OF THE INVENTION Accordingly, an essential object of the present invention is to provide an improved variable output type compressor in which a valve provided with a driving member made of shape memory alloy is incorporated such that electric current applied to the driving means is controlled, with substantial elimination of the disadvantages inherent in conventional compressors of this kind. Another important object of the present invention is to provide an improved compressor of the above described type which is simple in structure, compact in size and can be manufactured at low cost. In accomplishing these and other objects according to on preferred embodiment of the present invention, there is provided an improved compressor comprising: a fixed member; a movable member which is movable relative to said fixed member such that a cylinder chamber for effecting suction and compression strokes of refrigerant therein is defined between said fixed member and said movable member; said fixed member being formed with a plurality of suction ports for the refrigerant and a discharge port for the refrigerant such that said suction ports and said discharge port open into said cylinder chamber; a valve which is connected with a passage communicating, through one of said suction ports, with said cylinder chamber; said valve including a member which is made of shape memory alloy such that said valve opens or closes said passage upon expansion or contraction of said member; and a power source for supplying electric power to said member. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal sectional view of a prior art variable output type compressor (already referred to); Fig. 2 is a cross-sectional view of a compressor according to a first embodiment of the present invention; Fig. 3 is a schematic view of the compressor of Fig. 2, to which a double port suction method is applied; Fig. 4 is a longitudinal sectional view taken along the line IV-IV in Fig. 2; Fig. 5 is an exploded perspective view of the compressor of Fig. 2; Fig. 6 is a cross-sectional view taken along the line VI-VI in Fig. 5; ; Fig. 7 is a schematic view of a temperature actuator employed in the compressor of Fig. 2, with the temperature actuator being in a control cancel mode; Fig. 8 is a view similar to Fig. 7, particularly showing the temperature actuator of Fig. 7 in a control mode; Fig. 9a is a graph showing relation between voltage applied to a spring of the compressor of Fig. 2 and time; Fig. 9b is a graph indicative of variations of temperature of the spring of Fig. 9a with time; Figs. 10a and 10b are graphs similar to Figs. 9a and 9b, respectively, particularly showing a modification thereof; Figs. 11 to 14 are views similar to Fig. 7, particularly showing a temperature actuator employed in a compressor according to a second embodiment of the present invention; Fig. 15 is a graph showing PV characteristics of the compressor of Fig. 2; ; Figs. 16a to 16c are cross-sectional views of the compressor of Fig. 2 during a suction stroke; Fig. 17 is a graph showing changes of suction area of the compressor of Fig. 2 during the suction stroke; Fig. 18 is a view similar to Fig. 3, particularly showing a compressor according to a third embodiment of the present invention, to which a bypass method is applied; Fig. 19 is a longitudinal sectional view of the compressor of Fig. 18; Figs. 20 and 21 are detail views of a valve employed in the compressor of Fig. 18; Fig. 22 is a view similar to Fig. 20, particularly showing a modification thereof; and Fig. 23 is a view similar to Fig. 18, particularly showing a compressor according to a fourth embodiment of the present invention, to which an unloading-cylinder method is applied. Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout several views of the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, there is shown in Figs. 2 to 8, a compressor K1 for use in an air conditioner and the like, according to a first embodiment of the present invention. Fig. 3 schematically shows refrigerant passages connected with the compressor K1 arranged to adjust refrigerating capability of the air conditioner. The compressor K1 generally includes a cylinder 11 formed with a vane chamber, i.e., a cylinder chamber 41, axially extending therethrough, vanes 12, a rotor 14 rotatably provided in the cylinder chamber 41 and formed with grooves 13 for receiving the vanes 12 slidably therein, respectively, passages 23, 24, 26 and 27 and a supply source 28 for the refrigerant. The cylinder 11 is further formed with suction ports 15 and 17 opening into the cylinder chamber 41 and a discharge port 22 opening into the cylinder chamber 41. The passages 23 and 24 are, respectively, communicated with the cylinder chamber 41 through the suction ports 15 and 17, while the passage 27 is led from the passage 24 such that the passages 23 and 27 are connected with the passage 26 provided with the supply source 28. A main valve 25 is provided between the passages 24 and 27. In Fig. 3, when control of the refrigerating capability of the air conditioner cancelled in the compressor K1, the refrigerant is supplied into the vane chamber 41 via the suction ports 15 and 17 during a suction stroke of the cylinder 11. In the case where the main valve 25 is closed so as to prevent the refrigerant from being supplied from the suction port 17, the refrigerant is supplied into the vane chamber 41 only through the suction port 15, whereby the refrigerating capability of the air conditioner is reduced by about 40 to 50%. Referring to Fig. 4, the compressor K1 further includes a rear plate 40, a front plate 42 confronting the rear plate 40, a rotary shaft 43 coupled with the rotor 14, a rear casing 44 coupled with the rear plate 40, a spool having a head portion 47, a compression spring 46 wound around the spool 45, a plug 49 provided with a sealing member 48, and a sealing member 50 provided between the rear plate 40 and the rear casing 44. In the compressor K1, a back pressure portion 51 is defined between the head portion 47 of the spool 45 and the plug 49 and oil 52 is filled into the rear casing 44. It is to be noted that the main valve 25 is constituted by the spool 45, the compression spring 46 and the suction port 17. In Fig. 4, the compressor K1 is in a control cancel mode for cancelling control of the refrigerating capability of the air conditioner, in which the spool 45 is displaced leftwards by the compression spring 46 due to low pressure of the back pressure portion 51. It is to be further noted that the vanes 12, and the rotor 14 are movable members, while the cylinder 11, the rear plate 40 and the front plate 42 are fixed members such that the cylinder chamber 41 is defined between the movable members (vanes 12 and rotor 14) and the fixed members (cylinder 11, rear plate 40 and front plate 42). In Figs. 5 and 6, the compressor K1 further includes a pilot valve, 66 for controlling the main valve 25 and the pilot valve 66 is adapted to be actuated by a coiled tension spring 54 made of shape memory alloy. More specifically, the compressor K1 includes a spool 52, a coiled tension spring 53 made of ordinary metal other than shape memory alloy, a valve casing 55 for accommodating the pilot valve 66 therein, and upper and lower covers 56 and 57 provided at upper and lower portions of the spring casing 55, respectively. The spool 52 has a small diameter portion 65 formed at a central portion thereof. The coiled tension spring 53 is held between hook members 58 and 60 which are secured to a lower portion of the upper cover 56 and an upper portion of the spool 52, respectively. Meanwhile, the coiled tension spring 54 is held between hook members 59 and 61 which are, respectively, fixed to an upper portion of the lower cover 57 and a lower portion of the spool 52. Openings 62, 64 and 63 for accommodating the coiled tension spring 53, the spool 52 and the coiled spring 54, respectively, are formed in the valve casing 55 so as to extend in alignment with one another in this order. Namely, the pilot valve 66 is mainly constituted by the spool 52, coiled tension springs 53 and 54 and upper and lower covers 56 and 57. It should be noted that the valve casing 55 is formed at a rear portion of the rear casing 44. Hereinbelow, actuation of the main valve 25, which is controlled by the pilot valve 25 including the coiled tension spring 54 made of shape memory alloy, will be described with reference to Figs. 7 and 8. In Fig. 7, an electrical circuit of the compressor K1 includes a power source 68 having the coiled tension spring 54 as its load and a switch 69. The compressor K1 includes a low-pressure and low-temperature supply source of the refrigerant and a high-pressure and high-temperature discharge side for the refrigerant. The supply source has a supply pressure Ps and the discharge side has a discharge pressure Pd. The compressor K1 further includes a passage 70 for connecting the supply source Ps and the opening 64, a passage 71 for connecting the discharge side and the opening 64, a passage 72 for connecting the passages 70 and 71, a passage 73 for connecting the passage 72 and the back pressure portion 51 of the main valve 25, a passage 74 for connecting the supply source and the opening 63, and a passage 75 for connecting the supply source and the opening 62. In this embodiment, a 12-volt battery commonly used for motor vehicles was employed as the power source 68. When the switch 69 is in an "off" state as shown in Fig. 7, a voltage of the power source 68 is not applied to the coiled tension spring 54 and thus, the coiled tension spring 54 is held in an expanded state. At this time, since the back pressure portion 51 of the main valve 25 is communicated with the low-pressure supply source through the passage 70, the opening 64 and the passages 72 and 73 sequentially, the spool 45 is displaced leftwards in Fig. 7 so as to be held in the control cancel mode for cancelling control of the refrigerating capability of the air conditioner. In this embodiment, Ni-Ti alloy, which has a transformation point of 40 to 500C and is held in a contracted state when subjected to high temperatures above the transformation point, was employed as shape memory alloy for the coiled tension spring 54. Meanwhile, the opening 62 for the coiled tension spring 53 and the opening 63 for the coiled tension spring 54 are communicated with the supply source for the refrigerant through the passages 75 and 74, respectively, and thus, are held at low temperature and lower pressure at all times. On the other hand, when the switch 69 is in an "on" state as shown in Fig. 8, the voltage of the power source 68 is applied to the coiled tension spring 54, so that the temperature of the coiled tension spring 54 rises. Thus, when the coiled tension spring 54 is heated higher than the transformation point, the coiled tension spring 54 is contracted so as to displace the spool 52 leftwards in Fig. 8. As a result, since the high-pressure discharge side having the discharge pressure Pd is communicated with the back pressure portion 51 of the main valve 25 through the passage 71, the opening 64 and the passage 73 sequentially, the spool 45 is displaced rightwards in Fig. 8 against an urging force of the compression spring 46 so as to close the suction port 17, so that the refrigerating capability of the air conditioner is reduced and thus, the compressor K1 is in a control mode for controlling the refrigerating capability of the air conditioner. In order to prevent excessive heat generation of the coiled tension spring 54 during the control mode, the power source 68 of the compressor K1 is turned on and off intermittently as shown in Fig. 9a such that the voltage of the power source 68 has a pulse width T1 and a pulse period TO. Accordingly, temperature t of the coiled tension spring 54 varies periodically as shown in Fig. 9b. When the pulse width T1 and the pulse period TO are set such that a lowest value of the temperature t is higher than a transformation point tl, it becomes possible to prevent excessive heat generation of the coiled tension spring 54. It is to be noted that excessive heat generation of shape memory alloy results in deterioration of shape memory effect of the shape memory alloy. Referring to Fig. 10, there is shown a modification of Fig. 9. In Fig. 10, responsive characteristics of rise at the time of changeover from cancellation of control of the refrigerating capability off the air conditioner to start of control of the refrigerating capability of the air conditioner are improved. Namely, the voltage is continuously applied to the coiled tension spring 54 in a duration Ts immediately after the changeover and then, is intermittently applied to the coiled tension spring 54 in the same manner as shown in Fig. 9 after the coiled tension spring 54 has been heated sufficiently higher than the transformation point tl. Referring to Figs. 11 to 14, there is shown a temperature actuator employed in a compressor K2 according to a second embodiment of the present invention. The temperature actuator of the compressor K2 includes, so to speak, a "bistable multiple circuit" having a self-retaining function. By an arrangement of the temperature actuator of the compressor K2 as will be described below, changeover between the control cancel mode for cancelling control of the refrigerating capability of the air conditioner and the control mode for controlling the refrigerating capability of the air conditioner can be sequentially effected when one pulse having a proper pulse width is applied to a compression spring made of shape memory alloy. Namely, the temperature actuator of the compressor K2 includes compression springs 100 and 101 made of shape memory alloy, a spool 102 having a small diameter portion 109 formed at a central portion thereof, power sources 105 and 106 and switches 107 and 108. The power source 105 and the switch 107 are provided for the compression spring 103, while the power source 106 and the switch 108 are provided for the compression spring 104. Openings 103, 110 and 104 for accommodating the compression spring 100, the spool 102 and the compression spring 101, respectively, are so provided as to extend in alignment with one another in this order. It is to be noted that characters Psc and Psd represent a suction pressure and an intermediate pressure, respectively. The temperature actuator of the compressor K2 further includes a passage 111 for connecting the supply source of the refrigerant and the opening 110 for the spool 102, a passage 112 for connecting the intermediate pressure Psd and the opening 110, a reservoir portion 113 provided in the course of the passage 112, a passage 114 for connecting the opening 104 and'the suction pressure Psc, a passage 115 for connecting the back pressure portion51 of the main valve 25 and the opening 110, a passage 116 branched from the passage 115 and communicating with the opening 110, a passage 117 branched from the passage 116 and communicating with the opening 103 for the compression spring 100, and a passage 118 branched from the passage 111 and communicating with the opening 104 for the compression spring 101. The compression springs 100 and 101 made of shape memory alloy are so manufactured as to be held in an expanded state at temperatures higher than the transformation point such that the following conditions (1) - to (3) are satisfied. (1) Supposing that the compression springs 100 and 101 having urging forces Fa and Fb, respectively, in the state shown in Fig. 11 at the same ambient temperature lower than the transformation point, relation between the urging forces Fa an Fb is given by: Fb > Fa (2) In the case where ambient temperature of the compression spring 100 is higher than the transformation point while ambient temperature of the compression spring 101 is lower than the transformation point, relation between the urging forces Fa and Fb is expressed by: Fa > Fb (3) In the case where ambient temperature of the compression spring 100 is lower than the transformation point and ambient temperature of the compression spring 101 is higher than the transformation point when an end face of the spool 102 has an area S, the following relation exists: : Fb > Psd S In Fig. 11, the compressor K2 is in the control cancel mode for cancelling control of the refrigerating capability of the air conditioner. At this time, the switch 107 for the power source 105 and the switch 108 for the power source 106 are in an "off" state. A small amount of the low-temperature refrigerant is supplied from the supply source into the opening 103 for the compression spring 100 via the passage 111, the opening 110, and the passages 116 and 117 so as to be drawn out of the opening 103 into a passage having the suction pressure Psc. Meanwhile, a small amount of the low-temperature refrigerant is supplied from the supply source into the opening 104 for the compression spring 101 through the passages 111 and 118 so as to be carried out of the opening 104 into the passage 114 leading to the passage having the suction pressure Psc. Accordingly, since both the compression springs 100 and 101 are maintained at ambient temperatures lower than the transformation point, the above described condition (1) is satisfied, so that the spool 102 is displaced rightwards in Fig. 11. Furthermore, since the back pressure portion 51 of the main valve 25 is communicated with the low-pressure supply source through the passage 111, the opening 110 and the passage 115, the spool 45 is displaced leftwards in Fig. 11. In Fig. 12, the switch 107 is turned on from the state of Fig. 11. In accordance with the above condition (2), the spool 102 is displaced leftwards. Thus, since the intermediate pressure Psd is introduced into the back pressure portion 51 of the main valve 25 via the passage 112, the reservoir portion 113, the opening 110 and the passages 116 and 115. Consequently, the spool 45 is displaced rightwards such that control of the refrigerating capability of the air conditioner is started. At the same time, the intermediate pressure Psd is introduced into the opening 103 for the compression spring 100 through the passage 112, the reservoir portion 113, the opening 110 and the passage 103. In Fig. 13, the switch 107 is turned off from the state of Fig. 13. Since heat generation of the compression spring 100 does not take place, the compression spring 100 is cooled rapidly by the refrigerant supplied under the intermediate pressure Psd. Since such a phenomenon occurs in the course of the compression stroke, temperature of a location having the intermediate pressure Psd is higher than that of the supply source but is far lower than the transformation point. However, forces fa and fb generated by pressures applied to right and left end faces of the spool 102, respectively are given by the equations: fa = Psd . S fb = Ps S Thus, since, the force fa is larger than the force fb, the spool 102 is held in the same state as in the case where the voltage is applied to the compression spring 100 (Fig. 12). In Fig. 14, the switch 108 is turned on from the state of Fig. 13. Since the above condition (3) is satisfied at this time, the spool 102 is displaced rightwards. As a result, the refrigerant under the intermediate pressure Psd is prevented from being supplied to the opening 103. Thus, since the opening 103 is communicated with the supply source through the passage 111, the opening 110 and the passages 116 and 117, the above condition (1) is satisfied again. Accordingly, even if the switch 108 is set to the "off" state, the spool 102 is held in the same state as shown in Fig. 11. As is clear from the foregoing description, it becomes possible to effect changeover between the control cancel mode and the control mode only by applying to either one of the compression springs 100 and 101 pulses having a proper pulse width. Therefore, by employing this method, it becomes positively possible to prevent deterioration of characteristics of shape memory alloy due to excessive heat generation of the shape memory alloy. Furthermore, since electric power for the changeover between the control cancel mode and the control mode is required only at the time of start of the changeover, power consumption required for driving the compressor can be reduced drastically. Referring to Fig. 15, there is shown PV characteristic of the compressor K1. In Fig. 15, curves A and B indicate states of the control cancel mode and the control mode, respectively. Meanwhile, since characters Psc and Ps represent the suction pressure and the supply pressure, respectively, the suction supply Ps becomes larger than the suction pressure Psc due to pressure drop. Furthermore, in Figs. 11 to 14, the reservoir portion 113 is provided between the passage having the intermediate pressure Psd and the opening 110 for the spool 102 so as to function as an accumulator for stabilizing variations of the intermediate pressure Psd. Since only a small amount of the refrigerant is required to flow from the passage having the intermediate pressure Psd, volume of the reservoir portion 113 can be made sufficiently small. In the compressor K1, it is so arranged that control of the refrigerating capability of the air conditioner is effected by closing one of the two ports communicating with the vane chamber. Hereinbelow, a principle of control of the refrigerating capability of the air conditioner in the compressor K1 will be described with reference to Figs. 16 and 17. Initially, the suction stroke of the compressor K1 in the control cancel mode is described with reference to Figs. 16a to 16e. In Fig. 16, the compressor K1 includes an upper portion 19 of the cylinder 11, and vanes 20a and 20b defining a vane chamber 18a therebetween. The rotor 14 is rotated about its rotary axis 0 in the counterclockwise direction in Fig. 16. An angle e is measured about the rotary axis 0 in the counterclockwise direction in Fig. 16 at an arbitrary position of a tip of the vane 20a by setting the angle e to zero when the tip of the vane 20a passes by the upper portion 19 of the cylinder 11. Fig. 16a shows a state in which the vane 20a has just passed by the upper portion 19. Fig. 16b shows a state in which the vane 20a is disposed between the suction ports 15 and 17 such that the refrigerant is supplied into the vane chamber 18a only via the suction port 15. Fig. 16c shows a state in which the vane 20a has passed by the suction port 17 and the vane 20b following the vane 20a is now passing by the suction port 15. Thereafter, supply of the refrigerant into vane chamber 18a via the suction port 15 is prevented by the vane 20b such that supply of the refrigerant into the vane chamber 18a via the suction port 17 is started. Fig. 16d shows a state in which the refrigerant is supplied into the vane chamber 18a only through the suction port 17. Fig. 16e shows a state in which the vane 20b has just passed by the suction port 17. In Fig. 16e, since supply of the refrigerant into the vane chamber 18a through the suction port 17 is prevented by the vane 20b, the suction stroke of the cylinder 11 is completed at this time. Meanwhile, in compressors each provided with four vanes, it is usually so arranged that the angle e in Fig. 16e is set to 2250 approximately and volume of the vane chamber 18a reaches a maximum value at this time. Referring to Fig. 17, there are shown changes of effective area of the passages leading to the vane chamber in the compressor K1. In Fig. 17, a solid line C and a 6ne- dot chain line D respectively indicate the control cancel mode (Fig. 16) and a state in which the refrigerant is prevented from flowing into the vane chamber through the suction port 17 by closing the main valve 25 (Fig. 3). When the main valve 25 is closed, the refrigerant is prevented from flowing into the vane chamber 18a through the suction port 17 as shown in Fig. 16d. As described earlier, the curves A and B in Fig. 15 indicate the states of the control cancel mode and the control mode, respectively. In the case of the curve B, pressure of the refrigerant drops sharply from a point corresponding to the angle Q of 1350 (Fig. 17) upon closing of the passage, and thus, a total weight of the refrigerant is reduced extremely at the time of completion of the suction stroke, i.e., at a point b in Fig. 15. In the above embodiments, in order to close or open the main passage, the pilot valve provided with the member made of shape memory alloy was employed. However, it can be also so arranged that, for example, the spring 46 (Fig. 4) for the main valve 25 is made of shape memory alloy such that the main passage is directly closed or opened by the main valve 25. Referring to Figs. 18 and 19, there is shown a compressor X3 according to a third embodiment of the present invention, to which a bypass method is applied. The compressor K3 includes a cylinder 311 formed with a vane chamber, i.e., a cylinder chamber 322 axially extending therethrough, vanes 312, a rotor 314 rotatably provided in the cylinder chamber 322 and formed with grooves 313 for receiving the vanes 312 slidably therein, respectively, passages 318 and 319, a valve 320 (hereinbelow, referred to as an "SMA valve") provided with a member made of shape memory alloy, and a supply source 321 for the refrigerant. The cylinder 311 is further formed with suction ports 315 and 316 opening into the cylinder chamber 322 and a discharge port 317 opening into the cylinder chamber 322. The cylinder chamber 322 is defined by the vanes 312, rotor 314, cylinder 311 and side plates of the cylinder 311. In Fig. 18, when the SMA valve 320 is in a closed state, the refrigerant is sucked into the cylinder chamber 322 through the suction ports 315 and 316 and thus, suction and compression of the refrigerant are performed in the control cancel mode for cancelling control of the refrigerating capability of the air conditioner. When the SMA valve 320 is in an open state, the refrigerant filled into the cylinder chamber 322 after the suction stroke is returned to the supply source 321 through the passage 319 and thus, the refrigerating capability of the air conditioner is controlled by the compressor K3. Referring to Fig. 19, the compressor K3 further includes a rear plate 323, a front plate 324 confronting the rear plate 323, a rotary shaft 325 coupled with the rotor 314, a rear casing 324 coupled with the rear plate 323, a clutch pulley 327, a discharge pipe joint 328, a suction pipe joint 329, a head cover 330 formed with a suction chamber 331, an intermediate plate 333 and a wire 334 for supplying electrical power to the SMA valve 320. The compressor K3 is formed with a through-hole 332 communicating with the suction chamber 331 and the passage 318. Meanwhile, the passages 318 and 319 are defined between the rear plate 323 and the intermediate plate 333. Referring to Figs. 20 and 21, there is shown the SMA valve 320 in the open and closed states, respectively. The SMA valve 320 includes a circular plate 335 formed with an opening 337, a spool 336, a bolt 338 for securing the plate 335 to the spool 336, a torsion spring 339 wound around the spool 336, a torsion spring 340 (hereinafter referred to as an HSMA spring") made of shape memory alloy and wound around the spool 336, a ball 341 provided at a lower end of the spool 336 for supporting the spool 336, a casing 342 secured to the intermediate'plate 333 with bolts 343, and a bolt 346 acting as a stopper for the plate 335. The rear plate 323 is formed with a through-hole 344. The rear plate 323 is formed with a recess 345 for receiving the plate 335 rotatably therein, while the plate 335 is formed with a groove 347. The torsion spring 339 has one end 348 secured to the spool 336 and the other end 349 secured to the intermediate plate 333. The SMA spring 340 has one end 350 secured to the spool 336. The SMA valve 320 further includes an electrically insulating plate 351 and the SMA spring 340 has the other end 352 secured to the insulating plate 351. In Figs. 20a and 20b, a voltage is applied to the SMA spring 340 by a battery provided outside the SMA valve 320 such that electric current is sequentially passed through respective conductive members, i.e., the wire 334, other end 352, SMA spring 340, one end 350, spool 336, torsion spring 339, other end 349 and intermediate plate 333. Namely, input terminals of the SMA valve 320 connected to two terminals of the power source are the wire 334 and the compressor X3 (ground). In the compressor X3, Ni-Ti alloy having a transformation point of 40 to 500C was employed as shape memory alloy for the SMA spring 340. It is so arranged that when temperature of the SMA spring 340 exceeds the transformation point, the SMA spring 340 is so actuated as to rotate the spool 336 and the plate 335 in the clockwise direction as indicated by the arrow A in Fig. 20a. Therefore, when electric current is passed through the SMA spring 340, temperature of the SMA spring 340 reaches the transformation point due to its heat generation, so that the plate 335 is rotated until the plate 335 is prevented from being rotated further upon contact of the plate 335 with the bolt 346. Thus, since the opening 337 of the plate 335 is disposed just above the through-hole 344 of the rear plate 323, the vane chamber 322 is communicated with the passage 319 leading to the supply source 321 for the refrigerant. Namely, since the refrigerant filled into the vane chamber 322 after the suction stroke is again returned (bypassed) to the supply source 321, control of the refrigerating capability of the air conditioner is effected to a large extent. On the contrary, when the power source of the SMA spring 340 is turned off, temperature of the SMA spring 340 drops down below the transformation point. Thus, the plate 335 is rotated by a restoring force of the torsion spring 339 in the counterclockwise direction as indicated by the arrow B in Fig. 21a until the plate 335 is prevented from being rotated further upon contact of the plate 335 with the bolt 346. At this time, since the through-hole 344 is shielded by the plate 335, the vane chamber 322 is disconnected from the passage 319 acting as a bypass and thus, the compressor K3 is in the control cancel mode for cancelling control of the refrigerating capability of the air conditioner. By the above described arrangement of the SMA valve 320 comprising the SMA spring 340 made of shape memory alloy and having a torsional restoring force and the torsion spring 339 in combination, it becomes possible to control the refrigerating capability of the air conditioner by the compressor K3 having a remarkably simple construction as compared with conventional compressors employing solenoid valves. Since the plate 335 confronting the vane chamber 322 is rotated flush with the surface of the rear plate 323, drop of efficiency of the compressor K3 due to clearance volume at the time of the control cancel mode does not take plate. This is because the opening 337 is shielded by the rotor 314 in the control cancel mode as shown in Fig. 21b. It is dimensionally so arranged that a small clearance of a few times ten microns is defined between the rotor 314 and the rear plate 323. Referring to Fig. 22, there is shown a compressor K3' which is a modification of the compressor K3, whose response property is improved. The compressor K3' includes a passage 358 for connecting the passage 319 and a space 359 formed in the casing 342 for accommodating the SMA spring 340, a passage 360 for connecting the space 359 and a vane chamber 361 disposed at the side of the suction ports, and a hole 362 led from the passage 360 and opening into the vane chamber 361. The SMA spring 340 is heated by passing electric current therethrough. Then, when the power source is turned off, it takes a long time due to heat capacity of the SMA spring 340 to allow the SMA spring 340 to drop in temperature. Acuators employing members made of shape memory alloy have been hitherto proposed in the field of robots, etc. but have such a fatal drawback as the above described poor response--property. However, in the compressor K3', such a fact is taken into consideration that the compressor of the refrigerating cycle is provided with the refrigerating source. Thus, in the compressor K3', the low-temperature refrigerant is caused to flow through the passages 358 and 360 as indicated by the arrows in Fig. 22 so as to cool the SMA spring 340 rapidly, thereby improving the response property of the SMA spring 340. In the compressors K3 and K3', the valve includes the spring made of shape memory alloy and the ordinary spring. However, it can be also so arranged that the valve includes two springs made of shape memory alloy and the springs have restoring forces oriented in opposite directions, respectively so as to be alternately subjected to voltage. Referring further to Fig. 23, there is shown a compressor K4 according to a fourth embodiment of the present invention, to which an unloading cylinder method is applied. The compressor K4 includes a cylinder 500 formed with suction ports 502a and 502b and discharge ports 508a and 508b, a rotor 501, a main valve 503, a supply source 504 for the refrigerant, and a suction passage 505. Cylinder chambers 506a and 506b are defined between the rotor 501 and the cylinder 500. In the compressor K4, a pilot valve including a member made of shape memory alloy can be employed for opening or closing the main valve 503. In accordance with the present invention, since the member made of shape memory alloy and provided in the compressor is expanded or contracted when subjected to voltage so as to close or open the passage of the refrigerant such that the refrigerating capability can be easily adjusted externally of the compressor. Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as being includes therein.

Claims: What is claimed is: 1. A compressor (K1, K2, K3, K4) comprising: a fixed member (11, 40, 42); a movable member (12, 14) which is movable relative to said fixed member (11, 40, 42) such that a cylinder chamber (41) for effecting suction and compression strokes of refrigerant therein is defined between said fixed member (11, 40, 42) and said movable member (12, 14); said fixed member (11, 40, 42) being formed with a plurality of suction ports (15, 17) for the refrigerant and a discharge port (22) for the refrigerant such that said suction ports (15, 17) and said discharge port (22) open into said cylinder chamber (41); a valve (25, 66) which is connected with a passage (24, 27) communicating, through one (17) of said suction ports (15, 17), with said cylinder chamber (41); ; said valve (25, 66) including a member (54) which is made of shape memory alloy such that said valve (25, 66) opens or closes said passage (24, 27) upon expansion or contraction of said member (54); and a power source (68) for supplying electric power to said member (54). 2. A compressor (K1, K2) as claimed in Claim 1, wherein said member (54; 100, 101) is accommodated in said valve (25, 66) and a passage (74; 111, 116, 117, 118) for cooling said member (54; 100, 101) is defined between said valve (25, 66) and a suction side of the refrigerant. 3. A compressor (K1, X2, K3, K4) as claimed in Claim 1, wherein the electric power is intermittently supplied to said member (54) by said power source (68). 4. A compressor (K1, K2, K3, K4) as claimed in Claim 1, wherein said member (54) has a shape of a torsion spring and said valve (25, 66) is opened or closed when the electric power is supplied to said member (54) by said power source (68). 5. A compressor (K1, K2, K3, K4) comprising: a fixed member (11, 40, 42); a movable member (12, 14) which is movable relative to said fixed member (11, 40, 42) such that a cylinder chamber (41) for effecting suction and compression strokes of refrigerant therein is defined between said fixed member (11, 40, 42) and movable member (12, 14); said fixed member (11, 40, 42) being formed with a plurality of suction ports (15, 17) for the refrigerant and a discharge port (22) for the refrigerant such that said suction ports (15, 17) and said discharge port (22) open into said cylinder chamber (41); a valve (25, 66) which is communicated with said cylinder chamber (41) through one (17) of said suction ports (15, 17); said valve (25, 66) including a torsion spring (54) made of shape memory alloy; ; said valve (25, 66) opening or closing said one (17) of said suction ports (15, 17) upon expansion or contraction of said torsion spring (54) so as to control amount of the refrigerant flowing into said cylinder chamber (41); and a power source (68) for supplying electric power to said torsion spring (54).

Inventors: MARUYAMA, TERUO
Applicants: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1984
Main classification: F04C18
IPC codes: F04C18, F04C28