Motor compressor

Abstract

To prevent a refrigerant liquid from accumulating in a two-stage compression mechanism to secure reliability of a motor compressor.SOLUTION: A motor compressor (50) includes: a two-stage compression mechanism (110); a compressor housing (70) that defines an intermediate pressure chamber (71) that accommodates the two-stage compression mechanism (110) and a discharge chamber (144) into which a refrigerant is discharged from the two-stage compression mechanism (110); an intermediate pressure communication passage (145) that allows the intermediate pressure chamber (71) and the discharge chamber (144) to communicate; and an intermediate pressure relief valve (147) that allows the refrigerant to flow only from the intermediate pressure communication passage (145) to the discharge chamber (144).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an improved technology for an electric compressor including a compression mechanism that compresses refrigerant in two stages and a motor that drives this compression mechanism.

Background Art

[0002] Among electric compressors, there is a rolling piston type rotary compressor that performs two-stage compression. As such an electric compressor, for example, the technologies of Patent Document 1 and Patent Document 2 are known.

[0003] According to the technology known from Patent Document 1, the electric compressor has a two-stage compression mechanism in which, inside the housing, a low-stage compression mechanism is arranged below the motor, and a high-stage compression mechanism is arranged below this low-stage compression mechanism, which is a configuration of a so-called vertically placed electric compressor. The inside of the housing is partitioned by a partition member into a first sealed chamber that houses the motor and a second sealed chamber that houses the compression mechanism. The suction passage of the low-stage compression mechanism communicates with the first sealed chamber. The discharge passage of the low-stage compression mechanism opens into the second sealed chamber. The suction passage of the high-stage compression mechanism communicates with the second sealed chamber. The discharge passage of the high-stage compression mechanism communicates with a discharge chamber for high-pressure refrigerant. An injection pipe is connected to the second sealed chamber. Intermediate-pressure refrigerant is gas-injected from the circuit of the air conditioner into the second sealed chamber through the injection pipe, so that the second sealed chamber has an intermediate-pressure atmosphere.

[0004] Also, according to the technology known from Patent Document 2, in a two-stage compressor, the volume of the suction cylinder (compression chamber) of the high-pressure compression element mechanism is set to be equivalent to the volume of the refrigerant gas discharged from the low-pressure compression element mechanism, and is smaller than the volume of the suction cylinder (compression chamber) of the low-pressure compression element mechanism.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, like the technology known from Patent Document 1, when the compressor of the vehicle air conditioner stops for a long time without operating, the pressure in the refrigeration cycle becomes balanced, and the refrigerant gas in the refrigeration cycle liquefies at the coldest part in the refrigeration cycle. The compressor has the largest heat capacity among the components constituting the refrigeration cycle and is difficult to warm up following the change in the outside air temperature. Therefore, inside the compressor, liquefaction of the refrigerant gas in the refrigeration cycle occurs. When the refrigerant liquefies inside the compressor, the refrigerant liquid also accumulates in the first sealed chamber and the second sealed chamber.

[0007] When starting the operation of the electric compressor in a state where this refrigerant liquid has accumulated, the low-stage compression mechanism sucks the refrigerant liquid accumulated in the first sealed chamber and discharges it into the second sealed chamber. The high-stage compression mechanism sucks the refrigerant liquid accumulated in the second sealed chamber and discharges it into the discharge chamber. However, since the volume of the refrigerant liquid does not change even when compressed, the refrigerant liquid accumulates in the second sealed chamber by the difference in volume between the compression chamber of the low-stage compression mechanism and the compression chamber of the high-stage compression mechanism. If the operation continues further, the refrigerant liquid accumulated in the second sealed chamber further increases, and the refrigerant liquid may flow backward into the injection pipe connected to the second sealed chamber. As a result, normal refrigeration cycle operation becomes impossible.

[0008] In the technology known from Patent Document 2, a check valve is provided so that the refrigerant liquid does not flow backward into the injection pipe. However, just providing the check valve will cause the refrigerant liquid to continue to accumulate in the second sealed chamber. When the refrigerant liquid accumulates up to the total volume of the second sealed chamber, the pressure in the second sealed chamber will increase due to the discharge of the refrigerant liquid from the low-stage compression mechanism. If excessive pressure is generated, it is not preferable in terms of ensuring the reliability of the electric compressor from the viewpoints of the durability of the low-stage compression mechanism and the prevention of refrigerant leakage from the second sealed chamber.

[0009] The present invention has been made to solve the above-described problems, and an object thereof is to provide a technique capable of ensuring the reliability of an electric compressor by preventing the accumulation of refrigerant liquid in a two-stage compression mechanism.

Means for Solving the Problems

[0010] In the following description, reference numerals in the accompanying drawings are appended in parentheses to facilitate understanding of the present invention, but the present invention is not limited to the illustrated forms thereby.

[0011] According to the present disclosure, firstly, a two-stage compression mechanism (110) including a high-stage compressor (130) and a low-stage compressor (120) having a larger suction volume than the high-stage compressor (130), a motor (100) for driving the two-stage compression mechanism (110), an intermediate pressure chamber (71) for housing the two-stage compression mechanism (110), a discharge chamber (144) from which refrigerant is discharged from the two-stage compression mechanism (110), a compressor housing (70) defining the discharge chamber (144), an intermediate pressure communication passage (145) communicating the intermediate pressure chamber (71) and the discharge chamber (144), and an intermediate pressure relief valve (147) that allows only the flow of refrigerant from the intermediate pressure communication passage (145) to the discharge chamber (144) are provided, characterized by an electric compressor (50).

[0012] Secondly, preferably, the electric compressor according to the first aspect, wherein the intermediate pressure relief valve (147) is a reed valve including a first valve seat (147a) that opens and closes the intermediate pressure communication passage (145), a first stopper (147b) that regulates the opening amount of the first valve seat (147a), and a first fixing member (147c) that fixes the first valve seat (147a) and the first stopper (147b).

[0013] Thirdly, preferably, the electric compressor according to the second aspect, further including a discharge communication passage (146) that communicates a discharge passage (136) of the high-stage compressor (130) and the discharge chamber (144), and a discharge valve (148) that allows only the flow of refrigerant from the discharge communication passage (146) to the discharge chamber (144). The discharge valve (148) is a reed valve composed of a second valve sheet (148a) that opens and closes the discharge communication passage (146), a second stopper (148b) that regulates the valve opening amount of the second valve sheet (148a), and a second fixing member (148c) that fixes the second valve sheet (148a) and the second stopper (148b). The first valve sheet (147a) and the second valve sheet (148a) are a single integrated part. The first stopper (147b) and the second stopper (148b) are a single integrated part. The first fixing member (147c) also serves as the second fixing member (148c).

[0014] Fourthly, preferably, the electric compressor according to the first to third aspects, wherein the intermediate pressure chamber (71) and the discharge chamber (144) are arranged along the center line (CL1) of the rotating shaft (101) of the two-stage compression mechanism (110). The space between the intermediate pressure chamber (71) and the discharge chamber (144) is closed by a flat closing plate (143). The radially outer peripheral surface (143c) of the closing plate (143) faces the intermediate pressure chamber (71). Among the closing plate (143), the first end face (143a) perpendicular to the center line (CL1) covers the end face (134b) of the two-stage compression mechanism (110). Among the closing plate (143), the second end face (143b) opposite to the first end face (143a) faces the discharge chamber (144). The intermediate pressure communication passage (145) communicates from the outer peripheral surface (143c) of the closing plate (143) to the second end face (143b).

[0015] Fifthly, preferably, the electric compressor according to the first to fourth aspects, wherein the electric compressor (50) is a horizontally placed electric compressor capable of arranging the rotating shaft (101) of the two-stage compression mechanism (110) horizontally. The intermediate pressure communication passage (145) is located below the horizontally placed rotating shaft (101). The suction passages (125, 135) and discharge passages (126, 136) of the two-stage compression mechanism (110) are located above the horizontal rotation shaft (101).

Advantages of the Invention

[0016] In the present invention, by preventing the accumulation of the refrigerant liquid in the two-stage compression mechanism, the reliability of the electric compressor can be ensured.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0018] Embodiments of the present invention will be described below based on the accompanying drawings. Note that the embodiments shown in the accompanying drawings are examples of the present invention, and the present invention is not limited to these embodiments.

[0019] <Example> While referring to FIGS. 1 to 8, the electric compressor 50 of the embodiment and the injection refrigeration cycles 10 and 30 including this electric compressor 50 will be described.

[0020] FIG. 1A shows an example of an injection refrigeration cycle 10 (hereinafter abbreviated as "refrigeration cycle 10"). This refrigeration cycle 10 is used, for example, in an automotive air conditioner, and performs cooling and heating by an indoor air conditioning unit (not shown). Note that this refrigeration cycle 10 is not limited to the application. Further, this refrigeration cycle 10 is suitable for using R744 refrigerant, but other refrigerants (for example, R134a refrigerant and R1234yf refrigerant) can be used.

[0021] Here, the injection type means that in the refrigeration cycle 10, the high-pressure refrigerant is expanded in two stages, and the refrigerant gas (vapor-phase refrigerant) in which the intermediate-pressure gas-liquid separation is performed is returned to the electric compressor 50. The refrigerant gas at the intermediate pressure returned to this electric compressor 50 is called an injection refrigerant gas.

[0022] More specifically, the refrigeration cycle 10 includes an evaporator 11, a gas cooler 12, a first expansion valve 13, a second expansion valve 14, a gas-liquid separator 15, and an electric compressor 50.

[0023] The electric compressor 50 includes a two-stage compression mechanism 110. This two-stage compression mechanism 110 has a low-stage compressor 120 and a high-stage compressor 130. Further, the electric compressor 50 includes a suction port 68 capable of sucking refrigerant from the outside (evaporator 11), a discharge port 75 capable of discharging refrigerant to the outside (gas cooler 12), and an injection port 151 capable of introducing injection refrigerant gas.

[0024] The refrigerant outlet of the gas cooler 12 is connected to the refrigerant inlet of the gas-liquid separator 15 via the first expansion valve 13 by the first flow path 21. The refrigerant outlet of the gas-liquid separator 15 is connected to an injection pipe 22 through which the injection refrigerant gas flows and a second flow path 23 through which the refrigerant liquid flows. The injection pipe 22 is connected to the injection port 151 of the electric compressor 50.

[0025] The second flow path 23 is connected to the refrigerant inlet of the evaporator 11 via the second expansion valve 14. The refrigerant outlet of the evaporator 11 is connected to the suction port 68 of the electric compressor 50 by the third flow path 24. The discharge port 75 of the electric compressor 50 is connected to the refrigerant inlet of the gas cooler 12 by the fourth flow path 25.

[0026] The refrigerant flows in the direction indicated by the solid line in FIG. 1A. That is, the refrigerant heat-exchanged with the outside air by the gas cooler 12 flows through the first flow path 21, the first expansion valve 13, the gas-liquid separator 15, the second expansion valve 14, and the evaporator 11 to the suction port 68 of the electric compressor 50 and is compressed to a high pressure. The refrigerant compressed to a high pressure by the electric compressor 50 flows to the gas cooler 12 through the fourth flow path 25.

[0027] In this way, the refrigerant heat-exchanged with the outside air by the gas cooler 12 is rapidly adiabatically expanded by the first expansion valve 13 and the second expansion valve 14 and then returns to the evaporator 11. That is, the refrigerant discharged from the gas cooler 12 is expanded in two stages by the first expansion valve 13 and the second expansion valve 14.

[0028] The refrigerant at an intermediate pressure that has passed only through the first expansion valve 13 of the two expansion valves 13, 14 flows through the gas-liquid separator 15 and is sent to the injection inlet 151 of the electric compressor 50 by the injection pipe 22. By appropriately adjusting the opening degrees of the first expansion valve 13 and the second expansion valve 14 according to the operation requirements, the amount branched to the injection inlet 151 of the compressor 50 can be adjusted.

[0029] FIG. 1B shows another example of an injection type refrigeration cycle 30 (hereinafter abbreviated as "refrigeration cycle 30"). The refrigeration cycle 30 of this other example is provided with an internal heat exchanger 31 instead of the gas-liquid separator 15 of the refrigeration cycle 10. The refrigerant outlet of the gas cooler 12 is connected to the refrigerant inlet of the internal heat exchanger 31 by a first flow path 21. Among the first flow path 21, the section 21a between the gas cooler 12 and the internal heat exchanger 31, that is, the branch point 21a branches off by a branch path 41 and is connected to the inlet of the internal heat exchanger 31 via the first expansion valve 13. The outlet of the internal heat exchanger 31 is connected to the injection inlet 151 of the electric compressor 50 by an injection pipe 22.

[0030] In the refrigeration cycle 30 of the other example, the refrigerant branched from the section 21a between the gas cooler 12 and the internal heat exchanger 31, that is, the branch point 21a, is adiabatically expanded by the first expansion valve 13, then heated by the internal heat exchanger 31, and the heated refrigerant gas is made to flow to the injection inlet 151 of the electric compressor 50 by the injection pipe 22.

[0031] Next, the overall configuration of the electric compressor 50 will be described. As shown in FIG. 2, this electric compressor 50 has a configuration of a so-called horizontally-mounted electric compressor in which a two-stage compression mechanism 110 is arranged, for example, beside a motor 100. This electric compressor 50 includes a housing 51, a motor 100, and a two-stage compression mechanism 110 driven by this motor 100.

[0032] The housing 51 is configured to be installable horizontally. This housing 51 includes a motor housing 60 having a motor chamber 61 for housing the motor 100, a rear head 70 having an intermediate pressure chamber 71 for housing the two-stage compression mechanism 110, and a partition block 80 sandwiched between the motor housing 60 and the rear head 70. The motor housing 60, the rear head 70, and the partition block 80 are constituted by castings of a metal material such as aluminum (including aluminum alloy).

[0033] The motor housing 60 is a bottomed cylindrical member. One axial end of the motor housing 60 is closed by a bottom wall 62. This bottom wall 62 is integrally formed with the motor housing 60, for example. The other axial end of the motor housing 60 is entirely open. The open end face 63 of the motor housing 60 may be referred to as the first end face 63. This first end face 63 is a flat surface orthogonal to the axial center line CL1 of the motor housing 60. A motor chamber 61 is formed inside the motor housing 60. An inverter housing 65 is assembled to the outer wall surface 62a of the bottom wall 62 of the motor housing 60. An inverter device 66 for supplying driving power to the motor 100 is housed in this inverter housing 65.

[0034] Furthermore, the motor housing 60 has a suction port 68 for sucking refrigerant from the outside into the motor chamber 61. The third flow path 24 (refrigerant supply pipe 24) shown in FIG. 1 is connected to this suction port 68.

[0035] The rear head 70 (compressor housing 70) is a bottomed cylindrical member. One axial end of the rear head 70 is closed by a bottom wall 72. This bottom wall 72 is integrally formed with the rear head 70, for example. The other axial end of the rear head 70 is entirely open. The open end face 73 of the rear head 70 may be referred to as the second end face 73. This second end face 73 is a flat surface orthogonal to the axial center line CL1 of the motor housing 60 and faces the first end face 63 side of the motor housing 60.

[0036] Furthermore, the rear head 70 has an oil separation chamber 74 for separating oil from the refrigerant compressed by the two-stage compression mechanism 110, and a discharge port 75 for discharging the gaseous refrigerant (refrigerant gas) from which the oil has been separated by this oil separation chamber 74 to the outside. The fourth flow path 25 (refrigerant discharge pipe 25) shown in FIG. 1 is connected to this discharge port 75.

[0037] The partition block 80 is a disc-shaped member that partitions between the motor chamber 61 and the intermediate pressure chamber 71, and is sandwiched between the first end face 63 of the motor housing 60 and the second end face 73 of the rear head 70. Specifically, as shown in FIG. 3, this partition block 80 has a first mating surface 81 facing the first end face 63 of the motor housing 60 and the motor chamber 61, and a second mating surface 82 facing the second end face 73 of the rear head 70 and the intermediate pressure chamber 71. The first mating surface 81 and the second mating surface 82 are flat surfaces orthogonal to the axial center line CL1 of the motor housing 60. The first mating surface 81 and the second mating surface 82 may be appropriately referred to as the "first flat surface 81 and the second flat surface 82".

[0038] Between the first end face 63 of the motor housing 60 and the first mating surface 81 of the partition block 80, and between the second end face 73 of the rear head 70 and the second mating surface 82 of the partition block 80, they are each sealed by a sealing member (not shown) such as a gasket or an O-ring. The partition block 80 is restricted from both relative rotation and relative axial movement with respect to the motor housing 60 and the rear head 70. For example, the partition block 80 is integrally fixed together with the motor housing 60 and the rear head 70 by a fastening member 91 such as a bolt.

[0039] Next, the motor 100 will be described. As shown in FIG. 2, the motor 100 includes an output shaft 101 (motor shaft 101), a rotor 102 fixed to this output shaft 101, and a cylindrical stator 103 surrounding the periphery of this rotor 102.

[0040] The output shaft 101 rotates about the axial center line CL1 of the motor housing 60, extends from the motor chamber 61 toward the intermediate pressure chamber 71, penetrates through the partition block 80, and is drivably connected to the two-stage compression mechanism 110. That is, the output shaft 101 of the motor 100 can be arranged horizontally (for example, horizontally) and also serves as the rotating shaft 101 of the two-stage compression mechanism 110. Hereinafter, the output shaft 101 of the motor 100 may be appropriately referred to as the "rotating shaft 101 of the two-stage compression mechanism 110". This output shaft 101 (rotating shaft 101) is rotatably supported by a first bearing 104 provided on the partition block 80 and a second bearing 105 provided on the bottom wall 62 of the motor housing 60.

[0041] As shown in FIG. 3, the partition block 80 is integrally formed with a shaft support portion 83 for mounting the first bearing 104. That is, the partition block 80 integrally includes a shaft support portion 83 that supports the rotating shaft 101 of the two-stage compression mechanism 110. This shaft support portion 83 protrudes from the first mating surface 81 of the partition block 80 toward the motor chamber 61. Note that the shaft support portion 83 includes a configuration that directly supports the rotating shaft 101 without passing through the first bearing 104.

[0042] The axial center line CL1 of the motor housing 60 may be referred to as the "center line CL1 of the output shaft 101 (rotating shaft 101)". Note that the output shaft 101 of the motor 100 may be configured as a separate member from the output shaft of the two-stage compression mechanism 110. In that case, the output shaft 101 of the motor 100 is constituted by a connecting member such as a coupling with the output shaft of the two-stage compression mechanism 110.

[0043] The rotor 102 is rotatable with reference to the center line CL1 of the output shaft 101 (rotating shaft 101). The stator 103 is arranged on the radially outer side of the rotor 102 and is fixed to the inner peripheral surface 60b of the motor housing 60.

[0044] Next, the two-stage compression mechanism 110 will be described. As shown in Fig. 3, the low-stage compressor 120 and the high-stage compressor 130 that constitute the two-stage compression mechanism 110 are both of the so-called rolling piston type rotary compressor configuration, which compress by means of rotating bodies 122, 132 (pistons 122, 132) that perform rotational motion and cylinders 124, 134. The low-stage compressor 120 and the high-stage compressor 130 have substantially the same configuration and are arranged on the center line CL1 of the rotary shaft 101 (output shaft 101). The low-stage compressor 120, which has a larger suction volume than the high-stage compressor 130, is located on the side of the partition block 80 in the intermediate pressure chamber 71. The high-stage compressor 130 is located on the side of the bottom wall 72 of the rear head 70 in the intermediate pressure chamber 71.

[0045] Here, the suction volume refers to the stroke volume of the pistons 122, 132 when the rotary shaft 101 makes one rotation. That is, since the electric compressor 50 of the present invention employs a two-stage compression mechanism 110, by making the discharge volume (the volume of the compressed refrigerant) of the low-stage compression mechanism 120 the same as the suction volume of the high-stage compression mechanism 130, it is preferably set so that there is no stagnant refrigerant gas or insufficient refrigerant gas between the compressors 120, 130. As a result, the suction volume of the low-stage compression mechanism 120 becomes larger than the suction volume of the high-stage compression mechanism 130. On the premise of determining this volume, it is considered in terms of the compressible refrigerant gas.

[0046] The two-stage compression mechanism 110 will be described in more detail. As shown in Figs. 3 and 4, the low-stage compressor 120 includes a first eccentric shaft 121 provided integrally with the rotary shaft 101, an annular first piston 122 (first rotating body 122) fitted to the first eccentric shaft 121, and a flat first cylinder 124 having a first cylinder chamber 123 that allows the rotational motion of the first piston 122. The center line CL2 of the first eccentric shaft 121 is offset with respect to the center line CL1 of the rotary shaft 101.

[0047] The rotation of the first cylinder 124 is restricted relative to the rear head 70. The first cylinder 124 has a first surface 124a facing the second mating surface 82 side of the partition block 80 and a second surface 124b facing the second cylinder 134 side of the high-stage compressor 130. The first surface 124a and the second surface 124b of the first cylinder 124 are flat surfaces orthogonal to the axial center line CL1 of the motor housing 60.

[0048] The first cylinder chamber 123 is a perfect circular hole concentric with the center line CL1 of the rotating shaft 101 and penetrates the first cylinder 124. Further, the first cylinder 124 has a first suction passage 125 and a first discharge passage 126 communicating with the first cylinder chamber 123. The first suction passage 125 and the first discharge passage 126 open to the first surface 124a of the first cylinder 124.

[0049] The outer diameter of the first piston 122 is smaller than the inner diameter of the first cylinder chamber 123. A vertical plate-like first vane 127 is in contact with the outer peripheral surface of the first piston 122 so as to be able to advance and retreat. The tip of the first vane 127 is pressed against the outer peripheral surface of the first piston 122 by a first spring 128. The first vane 127 divides the first cylinder chamber 123 into a first suction chamber 123a and a first compression chamber 123b. The first suction chamber 123a communicates with the first suction passage 125. The first compression chamber 123b communicates with the first discharge passage 126. The first piston 122 revolves within the first cylinder chamber 123. The refrigerant introduced from the first suction passage 125 into the first suction chamber 123a (the first cylinder chamber 123) is compressed by the revolving motion of the first piston 122 and discharged through the first discharge passage 126 from the first compression chamber 123b.

[0050] As shown in FIGS. 3 and 5, the high-stage compressor 130, similar to the low-stage compressor 120, includes a second eccentric shaft 131 integrally provided on the rotating shaft 101, an annular second piston 132 (second rotating body 132) fitted onto the second eccentric shaft 131, and a flat-plate-shaped second cylinder 134 having a second cylinder chamber 133 that permits the rotational movement of the second piston 132. The center line CL3 of the second eccentric shaft 131 is offset with respect to the center line CL1 of the rotating shaft 101.

[0051] The relative rotation of the second cylinder 134 with respect to the rear head 70 is restricted. Further, the second cylinder 134 has a first surface 134a facing the second surface 124b side of the first cylinder 124 and a second surface 134b facing the bottom wall 72 side of the rear head 70. The first surface 134a and the second surface 134b of the second cylinder 134 are flat surfaces orthogonal to the axial center line CL1 of the motor housing 60.

[0052] The second cylinder chamber 133 is a perfect circular hole concentric with the center line CL1 of the rotating shaft 101 and penetrates the second cylinder 134. Further, the second cylinder 134 has a second suction passage 135 and a second discharge passage 136 that communicate with the second cylinder chamber 133. The second suction passage 135 communicates the second cylinder chamber 133 with the intermediate pressure chamber 71 by opening on the outer peripheral surface of the second cylinder 134. The second discharge passage 136 opens on the second surface 134b of the second cylinder 134.

[0053] The outer diameter of the second piston 132 is smaller than the inner diameter of the second cylinder chamber 133. A vertical plate-shaped second vane 137 is in contact with the outer peripheral surface of the second piston 132 so as to be able to advance and retreat. The tip of the second vane 137 is pressed against the outer peripheral surface of the second piston 132 by a second spring 138. The second vane 137 divides the second cylinder chamber 133 into a second suction chamber 133a and a second compression chamber 133b. The second suction chamber 133a communicates with a second suction passage 135. The second compression chamber 133b communicates with a second discharge passage 136. The second piston 132 revolves within the second cylinder chamber 133. The refrigerant introduced from the second suction passage 135 into the second suction chamber 133a (second cylinder chamber 133) is compressed by the revolving motion of the second piston 132 and discharged through the second discharge passage 136 from the second compression chamber 133b.

[0054] The center line CL2 of the first eccentric shaft 121 and the center line CL3 of the second eccentric shaft 131 are provided at positions symmetrical with respect to the center line CL1 of the rotating shaft 101.

[0055] As shown in FIG. 3, the first cylinder chamber 123 is closed on the partition block 80 side by a flat plate-shaped first closing plate 141. The first closing plate 141 is sandwiched between the second mating surface 82 of the partition block 80 and the first surface 124a of the first cylinder 124.

[0056] Furthermore, the first closing plate 141 has a first through hole 141a communicating with the suction port 125a of the first suction passage 125 and a second through hole 141b communicating with the first discharge passage 126. The first through hole 141a and the second through hole 141b penetrate in the plate thickness direction of the first closing plate 141.

[0057] The suction port 125a of the first suction passage 125 communicates with the suction passage 84 of the partition block 80 through the first through hole 141a of the first closing plate 141. This suction passage 84 penetrates the partition block 80 in the axial direction of the motor housing 60. That is, the suction passage 84 is provided inside the partition block 80. Therefore, the first cylinder chamber 123 communicates with the suction port 68 (see FIG. 2) of the motor housing 60 via the first suction passage 125, the first through hole 141a of the first closing plate 141, the suction passage 84 of the partition block 80, and the path of the motor chamber 61.

[0058] The partition block 80 has a communication groove 85 (discharge recess 85) that communicates the second through hole 141b of the first closing plate 141 with the intermediate pressure chamber 71. This communication groove 85 is formed on the second mating surface 82 of the partition block 80. A discharge valve 86 for opening and closing the opening of the second through hole 141b is provided in the communication groove 85. This discharge valve 86 is configured as a check valve, for example, a reed valve, that allows the flow of refrigerant only from the first discharge passage 126 to the communication groove 85. The first cylinder chamber 123 communicates with the second suction chamber 133a of the second cylinder chamber 133 via the first discharge passage 126, the second through hole 141b, the communication groove 85, the intermediate pressure chamber 71, and the second suction passage 135.

[0059] The space between the first cylinder chamber 123 and the second cylinder chamber 133 is closed by a flat second closing plate 142. This second closing plate 142 is sandwiched between the second surface 124b of the first cylinder 124 and the first surface 134a of the second cylinder 134.

[0060] The second cylinder chamber 133 is closed on the bottom wall 72 side of the rear head 70 by a flat third closing plate 143. This third closing plate 143 covers the entire second surface 134b of the second cylinder 134. Further, the third closing plate 143 is restricted from moving toward the bottom wall 72 side of the rear head 70 by the stepped surface 76 inside the rear head 70.

[0061] The first cylinder 124, the second cylinder 134, the first closing plate 141, the second closing plate 142, and the third closing plate 143 are axially clamped between the stepped surface 76 of the rear head 70 and the partition block 80.

[0062] Inside the rear head 70, a discharge chamber 144 partitioned by the bottom wall 72 and the third closing plate 143 is formed. That is, the intermediate pressure chamber 71 and the discharge chamber 144 are closed by the flat third closing plate 143. The intermediate pressure chamber 71 and the discharge chamber 144 are arranged along the center line CL1 of the rotating shaft 101 of the two-stage compression mechanism 110.

[0063] As shown in FIG. 6, the first end face 143a of the third closing plate 143 that is orthogonal to the center line CL1 of the rotating shaft 101 covers the second face 134b of the second cylinder 134 (two-stage compression mechanism 110). The second end face 143b of the third closing plate 143, which is opposite to the first end face 143a, faces the discharge chamber 144, that is, the bottom wall 72 of the rear head 70 shown in FIG. 3. The radially outer peripheral surface 143c of the third closing plate 143 faces the intermediate pressure chamber 71, that is, the inner peripheral surface 70a of the rear head 70 having a bottomed cylindrical shape.

[0064] As shown in FIG. 3, the third closing plate 143 has an intermediate pressure communication passage 145 that communicates the intermediate pressure chamber 71 and the discharge chamber 144, and a discharge communication hole 146 that communicates the second discharge passage 136 of the second cylinder 134 and the discharge chamber 144.

[0065] For example, as shown in FIG. 6, the intermediate pressure communication passage 145 is formed in an L shape having an inlet 145a on the radially outer peripheral surface 143c of the third closing plate 143 and an outlet 145b on the second end face 143b of the third closing plate 143. In the electric compressor 50 with the rotating shaft 101 oriented horizontally, the inlet 145a of the intermediate pressure communication passage 145 faces downward and is open to the intermediate pressure chamber 71. In the electric compressor 50 with the rotating shaft 101 oriented horizontally, the outlet 145b of the intermediate pressure communication passage 145 is preferably close to the lowermost end of the discharge chamber 144.

[0066] As shown in Fig. 3, in the discharge chamber 144, there are provided an intermediate pressure relief valve 147 that allows the flow of refrigerant only from the intermediate pressure communication passage 145 to the discharge chamber 144, and a discharge valve 148 that allows the flow of refrigerant only from the discharge communication passage 146 to the discharge chamber 144. These valves 147 and 148 are attached to the second end face 143b of the third closing plate 143.

[0067] As shown in Fig. 3, the intermediate pressure relief valve 147 is preferably set to open when the pressure in the intermediate pressure chamber 71 rises slightly above the pressure in the discharge chamber 144 due to the accumulation of refrigerant liquid in the intermediate pressure chamber 71. By doing so, the refrigerant liquid accumulated in the intermediate pressure chamber 71 can be quickly discharged to the discharge chamber 144, and an excessive pressure rise in the intermediate pressure chamber 71 can be prevented. This intermediate pressure relief valve 147 is a reed valve composed of a first valve seat 147a that opens and closes the intermediate pressure communication passage 145, a first stopper 147b that regulates the opening amount of the first valve seat 147a, and a first fixing member 147c such as a bolt that fixes the first valve seat 147a and the first stopper 147b.

[0068] The discharge valve 148 opens due to the differential pressure between the refrigerant gas pressure in the second compression chamber 133b and the internal pressure in the discharge chamber 144. This discharge valve 148 is a reed valve composed of a second valve seat 148a that opens and closes the discharge communication passage 146, a second stopper 148b that regulates the opening amount of the second valve seat 148a, and a second fixing member 148c that fixes the second valve seat 148a and the second stopper 148b.

[0069] Also refer to Figs. 7 and 8. The first valve seat 147a and the second valve seat 148a are a single part formed integrally. The first stopper 147b and the second stopper 148b are a single part formed integrally. The first fixing member 147c also serves as the second fixing member 148c.

[0070] Here, while referring to Fig. 3, the operating relationship between the intermediate pressure relief valve 147 and the discharge valve 148 will be described. During normal operation of the electric compressor 50, the discharge pressure of the second compression chamber 133b of the high-stage compressor 130 is higher than the pressure in the discharge chamber 144. The pressure in this discharge chamber 144 is higher than the pressure in the intermediate pressure chamber 71. At this time, the discharge valve 148 opens and the intermediate pressure relief valve 147 closes.

[0071] However, in the electric compressor 50, the refrigerant gas in the refrigeration cycle may liquefy and refrigerant liquid may accumulate in the internal spaces such as the motor chamber 61, the intermediate pressure chamber 71, and the discharge chamber 144. For example, when the electric compressor 50 has been stopped for a long time, the refrigerant gas in the refrigeration cycle may liquefy due to the temperature difference between day and night. Since the electric compressor 50 has a relatively large heat capacity among the components of the refrigeration cycle and is difficult to warm up and remains cold, refrigerant liquid is likely to accumulate. Also, the electric compressor 50 may be mounted at a low position so that the lubricating oil in the refrigerant gas easily returns from the refrigeration cycle to the electric compressor 50, and in that case, refrigerant liquid is likely to accumulate. As a result, the refrigerant liquid accumulates in the internal space of the electric compressor 50. When the operation of the electric compressor 50 in a state where refrigerant liquid has accumulated is started, the refrigerant liquid accumulated in the motor chamber 61 is sucked into the low-stage compressor 120 and sent to the intermediate pressure chamber 71. The refrigerant liquid accumulated in the intermediate pressure chamber 71 is sucked into the high-stage compressor 130 and sent to the discharge chamber 144. Also, the suction volume of the low-stage compressor 120 is larger than the suction volume of the high-stage compressor 130. Therefore, the amount of refrigerant liquid discharged from the low-stage compressor 120 is larger than the amount sucked into the high-stage compressor 130. The refrigerant liquid rapidly accumulates in the intermediate pressure chamber 71. As a result, it is assumed that the pressure in the intermediate pressure chamber 71 will rise rapidly prior to the discharge pressure of the high-stage compressor 130.

[0072] In contrast, the intermediate pressure relief valve 147 of the present invention is a differential pressure valve that opens when the pressure in the intermediate pressure chamber 71 rises even slightly above the pressure in the discharge chamber 144. When the pressure in the intermediate pressure chamber 71 rises even slightly above the pressure in the discharge chamber 114, the intermediate pressure relief valve 147 quickly opens to prevent the generation of an abnormally high pressure in the intermediate pressure chamber 71. As a result, the occurrence of refrigerant liquid leakage inside or outside the intermediate pressure chamber 71 can be prevented. This is the main reason for providing the intermediate pressure relief valve 147 in the electric compressor 50.

[0073] FIG. 7 shows a horizontally-mounted electric compressor 50 in which the rotating shaft 101 can be arranged horizontally. Arrow Up indicates the upper side with respect to the rotating shaft 101, and arrow Dn indicates the lower side. The motor housing 60 (see FIG. 3) is provided with installation brackets 69, 69 for arranging the electric compressor 50 horizontally. The intermediate pressure communication passage 145 is located below the horizontally arranged rotating shaft 101. The suction passages 125, 135 and the discharge passages 126, 136 of the two-stage compression mechanism 110 are located above the horizontally arranged rotating shaft 101.

[0074] As shown in FIG. 3, the discharge chamber 144 communicates with the oil separation chamber 74. The refrigerant in the high-stage compressor 130 can flow into the oil separation chamber 74 through the second discharge passage 136, the communication hole 146, and the discharge chamber 144. It is preferable that the tip of the rotating shaft 101 is rotatably supported by a third bearing 149 provided on the third closing plate 143.

[0075] As shown in FIG. 6, the partition block 80 has an injection inlet 151, an injection outlet 152, and an injection passage 153. The injection passage 153 communicates the injection inlet 151 and the injection outlet 152. At least the injection outlet 152 and the injection passage 153 are arranged inside the partition block 80.

[0076] The injection inlet 151 is integrally formed, for example, with the partition block 80. Specifically, on the outer peripheral surface 87 of the partition block 80, a boss portion 154 protruding radially outward is provided. The injection inlet 151 opens into this boss portion 154. The injection inlet 151 can introduce injection refrigerant gas when the injection pipe 22 (see FIG. 1) is connected thereto.

[0077] The injection outlet 152 communicates with the intermediate pressure chamber 71 by opening into the second mating surface 82 (second flat surface 82) of the partition block 80 facing the intermediate pressure chamber 71. Therefore, the injection outlet 152 can lead the injection refrigerant gas into the intermediate pressure chamber 71.

[0078] A check valve 160 is provided at the injection outlet 152. This check valve 160 allows the flow of the injection refrigerant gas only from the injection passage 153 to the intermediate pressure chamber 71. That is, when the pressure in the injection passage 153 increases until it exceeds the pressure in the intermediate pressure chamber 71, the check valve 160 opens due to the pressure difference.

[0079] This check valve 160 is provided on the flat second mating surface 82 of the partition block 80 facing the intermediate pressure chamber 71. This check valve 160 is constituted by, for example, a reed valve 161. One end of a plate having a thin elasticity of this reed valve 161 is fixed and it opens only in one direction, that is, only in the direction allowing the flow of the injection refrigerant gas from the injection passage 153 to the intermediate pressure chamber 71. As shown in FIG. 7, the injection outlet 152 is located above the horizontal rotation axis 101.

[0080] Next, the flow action of the refrigerant in the electric compressor 50 will be described. As shown in FIG. 2, the refrigerant (refrigerant gas) sucked from the suction port 68 of the motor housing 60 passes through the gap of the motor 100 disposed in the motor chamber 61, cools the motor 100, and then flows into the suction passage 84 of the partition block 80. The refrigerant that has passed through the suction passage 84 enters the first suction chamber 123a of the first cylinder chamber 123 through the first through hole 141a of the first closing plate 141 and the first suction passage 125 of the low-stage compressor 120.

[0081] As shown in FIG. 3, the refrigerant compressed by the low-stage compressor 120 flows from the first compression chamber 123b of the first cylinder chamber 123 through the first discharge passage 126, the second through hole 141b of the first closing plate 141, the communication groove 85 of the partition block 80, the intermediate pressure chamber 71, and the second suction passage 135 into the second suction chamber 133a of the second cylinder chamber 133. The refrigerant further compressed by the high-stage compressor 130 flows from the second compression chamber 133b of the second cylinder chamber 133 through the second discharge passage 136, the discharge communication passage 146 of the third closing plate 143, the discharge chamber 144, and the oil separation chamber 74 to the discharge port 75 of the rear head 70.

[0082] When the refrigerant liquid accumulates in the intermediate pressure chamber 71, the intermediate pressure relief valve 147 opens. The refrigerant liquid accumulated in the intermediate pressure chamber 71 is discharged to the discharge chamber 144 through the intermediate pressure communication passage 145.

[0083] Summarizing the above description, it is as follows.

[0084] As shown in FIG. 2, the electric compressor 50 includes a two-stage compression mechanism 110 having a high-stage compressor 130 and a low-stage compressor 120 with a larger suction volume than the high-stage compressor 130, a motor 100 for driving the two-stage compression mechanism 110, a compression housing 70 (rear head 70) that defines an intermediate pressure chamber 71 for housing the two-stage compression mechanism 110 and a discharge chamber 144 from which the refrigerant is discharged from the two-stage compression mechanism 110, an intermediate pressure communication passage 145 that communicates the intermediate pressure chamber 71 and the discharge chamber 144, and an intermediate pressure relief valve 147 that allows the flow of the refrigerant only from the intermediate pressure communication passage 145 to the discharge chamber 144.

[0085] Therefore, inside the two-stage compression mechanism 110, when refrigerant liquid accumulates in the intermediate pressure chamber 71 due to the liquefaction of the refrigerant gas during the refrigeration cycle and the pressure in the intermediate pressure chamber 71 rises even slightly, the intermediate pressure relief valve 147 opens, and the refrigerant liquid accumulated in the intermediate pressure chamber 71 can be quickly discharged to the discharge chamber 144. Thereby, the accumulation of the refrigerant liquid in the intermediate pressure chamber 71 can be prevented, and as a result, the generation of excessive pressure in the intermediate pressure chamber 71 can be prevented. Therefore, the durability of the two-stage compression mechanism 110 can be ensured, refrigerant leakage from the intermediate pressure chamber 71 can be prevented, and the reliability of the electric compressor 50 can be ensured.

[0086] As shown in FIG. 3, the intermediate pressure relief valve 147 is a reed valve constituted by a first valve seat 147a that opens and closes the intermediate pressure communication passage 145, a first stopper 147b that regulates the valve opening amount of the first valve seat 147a, and a first fixing member 147c that fixes the first valve seat 147a and the first stopper 147b.

[0087] The intermediate pressure relief valve 147 is constituted by a reed valve. For this reason, the intermediate pressure relief valve 147 can have a simple configuration with a small number of parts, and the valve opening amount of the intermediate pressure relief valve 147 can be easily set.

[0088] As shown in FIGS. 3 and 7, the electric compressor 50 further includes a discharge communication passage 146 that communicates the discharge passage 136 of the high-stage compressor 130 with the discharge chamber 144, and a discharge valve 148 that allows only the refrigerant flow from the discharge communication passage 146 to the discharge chamber 144. The discharge valve 148 is a reed valve composed of a second valve seat 148a that opens and closes the discharge communication passage 146, a second stopper 148b that regulates the opening amount of the second valve seat 148a, and a second fixing member 148c that fixes the second valve seat 148a and the second stopper 148b. The first valve seat 147a and the second valve seat 148a are a single part formed integrally. The first stopper 147b and the second stopper 148b are a single part formed integrally. The first fixing member 147c also serves as the second fixing member 148c.

[0089] In this way, the discharge valve 148 is configured as a reed valve. Therefore, the discharge valve 148 can have a simple configuration with a small number of parts, and the opening amount of the discharge valve 148 can be easily set. Moreover, by sharing the parts of the intermediate pressure relief valve 147 and the discharge valve 148, the number of parts of the intermediate pressure relief valve 147 and the discharge valve 148 can be reduced, and the assembly of each valve 147, 148 becomes easier.

[0090] As shown in FIG. 6, the intermediate pressure chamber 71 and the discharge chamber 144 are arranged along the center line CL1 of the rotating shaft 101 of the two-stage compression mechanism 110. The space between the intermediate pressure chamber 71 and the discharge chamber 144 is closed by a flat closing plate 143 (the third closing plate 143). The radially outer peripheral surface 143c of the closing plate 143 faces the intermediate pressure chamber 71. The first end face 143a of the closing plate 143 that is perpendicular to the center line CL1 of the rotating shaft 101 covers the end face 134b (the second face 134b of the second cylinder 134) of the two-stage compression mechanism 110. The second end face 143b of the closing plate 143 on the side opposite to the first end face 143a faces the discharge chamber 144. The intermediate pressure communication passage 145 communicates from the outer peripheral surface 143c of the closing plate 143 to the second end face 143b.

[0091] Thus, since the closing plate 143 has the intermediate pressure chamber 71 facing the outer peripheral surface 143c and the second end surface 143b facing the discharge chamber 144, an intermediate pressure communication passage 145 that communicates the intermediate pressure chamber 71 and the discharge chamber 144 can be easily formed.

[0092] As shown in FIGS. 3 and 7, the electric compressor 50 is a horizontally placed electric compressor in which the rotating shaft 101 of the two-stage compression mechanism 110 can be arranged horizontally. The intermediate pressure communication passage 145 is located below the horizontally placed rotating shaft 101. The suction passages 125 and 135 and the discharge passages 126 and 136 of the two-stage compression mechanism 110 are located above the horizontally placed rotating shaft 101.

[0093] The density of the refrigerant liquid is greater than the density of the refrigerant gas. For this reason, the refrigerant liquid accumulates on the lower sides of the intermediate pressure chamber 71 and the discharge chamber 144. On the other hand, the refrigerant gas accumulates on the upper side of 144. By arranging the intermediate pressure communication passage 145 on the lower sides of the intermediate pressure chamber 71 and the discharge chamber 144, the refrigerant liquid can be actively discharged from the intermediate pressure chamber 71 to the discharge chamber 144.

[0094] Note that as long as the functions and effects of the present invention are achieved, the present invention is not limited to the embodiments. For example, the compressor housing 70 (rear head 70) may have any configuration that defines the intermediate pressure chamber 71 and the discharge chamber 144, and is not limited to, for example, a configuration in which the second end surface 73 is open. Further, the compressor housing 70 includes a configuration in which the second end surface 73 is closed by a closing member such as a partition block 80. Further, the intermediate pressure communication passage 145 only needs to be able to connect the intermediate pressure chamber 71 and the discharge chamber 144, and may be formed by an oblique linear hole in the third closing plate 143 or may be formed in the rear head 70. Further, the motor 100 only needs to be able to drive the two-stage compression mechanism 110, and includes, for example, a configuration separated from the compressor housing 70.

Industrial Applicability

[0095] The electric compressor 50 of the present invention is suitable for use in the refrigeration cycles 10 and 30.

Explanation of Reference Numerals

[0096] 50 Electric compressor 70 Compressor housing (rear head) 71 Intermediate pressure chamber 80 Partition block 100 Motor 101 Rotating shaft (rotating shaft of two-stage compression mechanism) 110 Compression mechanism (two-stage compression mechanism) 120 Low-stage compressor 125 Suction passage of two-stage compression mechanism (first suction passage of low-stage compressor) 126 Discharge passage of two-stage compression mechanism (first discharge passage of low-stage compressor) 130 High-stage compressor 134b End face of two-stage compression mechanism (second face of second cylinder) 135 Suction passage of two-stage compression mechanism (second suction passage of high-stage compressor) 136 Discharge passage of two-stage compression mechanism (second discharge passage of high-stage compressor) 143 Closing plate (third closing plate) 143a First end face 143b Second end face 143c Radial outer peripheral surface 144 Discharge chamber 145 Communication passage for intermediate pressure 146 Communication passage for discharge 147 Intermediate pressure relief valve 147a First valve seat 147b First stopper 147c First fixing member 148 Discharge valve 148a Second valve seat 148b Second stopper 148c Second fixing member CL1 Center line

Claims

1. A two-stage compression mechanism (110) having a high-stage compressor (130) and a low-stage compressor (120) with a larger suction volume than the high-stage compressor (130); A motor (100) for driving the two-stage compression mechanism (110); A compressor housing (70) defining an intermediate pressure chamber (71) for housing the two-stage compression mechanism (110) and a discharge chamber (144) from which refrigerant is discharged by the two-stage compression mechanism (110); An intermediate pressure connecting passage (145) connecting the intermediate pressure chamber (71) and the discharge chamber (144); An electric compressor (50), comprising an intermediate pressure relief valve (147) that allows only the flow of refrigerant from the intermediate pressure connecting passage (145) to the discharge chamber (144).

2. The electric compressor according to claim 1, wherein the intermediate pressure relief valve (147) is a reed valve constituted by a first valve sheet (147a) that opens and closes the intermediate pressure connecting passage (145), a first stopper (147b) that regulates the opening amount of the first valve sheet (147a), and a first fixing member (147c) that fixes the first valve sheet (147a) and the first stopper (147b).

3. A discharge connecting passage (146) connecting the discharge passage (136) of the high-stage compressor (130) and the discharge chamber (144); Further comprising a discharge valve (148) that allows only the flow of refrigerant from the discharge connecting passage (146) to the discharge chamber (144), The discharge valve (148) is a reed valve constituted by a second valve sheet (148a) that opens and closes the discharge connecting passage (146), a second stopper (148b) that regulates the opening amount of the second valve sheet (148a), and a second fixing member (148c) that fixes the second valve sheet (148a) and the second stopper (148b), The first valve sheet (147a) and the second valve sheet (148a) are a single integrated part, The first stopper (147b) and the second stopper (148b) are a single integrated part, The electric compressor according to claim 2, wherein the first fixing member (147c) also serves as the second fixing member (148c).

4. The intermediate pressure chamber (71) and the discharge chamber (144) are arranged along the center line (CL1) of the rotation axis (101) of the two-stage compression mechanism (110), The space between the intermediate pressure chamber (71) and the discharge chamber (144) is closed by a flat closing plate (143). The radial outer peripheral surface (143c) of the closing plate (143) faces the intermediate pressure chamber (71). Of the closing plate (143), the first end surface (143a) orthogonal to the center line (CL1) covers the end surface (134b) of the two-stage compression mechanism (110). Of the closing plate (143), the second end surface (143b) on the side opposite to the first end surface (143a) faces the discharge chamber (144). The electric compressor according to claim 1, wherein the intermediate pressure communication passage (145) communicates from the outer peripheral surface (143c) of the closing plate (143) to the second end surface (143b).

5. The electric compressor (50) according to claim 1 is a horizontally placed electric compressor in which the rotating shaft (101) of the two-stage compression mechanism (110) can be arranged horizontally. The intermediate pressure communication passage (145) is located below the horizontally placed rotating shaft (101). The electric compressor according to claim 1, wherein the suction passages (125, 135) and the discharge passages (126, 136) of the two-stage compression mechanism (110) are located above the horizontally placed rotating shaft (101).

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