Electric compressor

Abstract

Provided is an electric compressor in which it is possible to obtain a higher cooling performance for switching elements than in the past.　In this electric compressor, a plurality of switching elements (61) constituting an inverter (6) are fixed to an element installation part (79) provided within an inverter housing (7), by means of a pressing member (20). The pressing member (20) has: a plurality of fixed parts (25a to 25d) fixed to a pressing member attachment part provided within the inverter housing (7); and a plurality of element pressing parts (27), each of which presses any one of the plurality of switching elements (61) against the element installation part (79). The pressing member (20) is formed of a material having thermal conductivity.

Description

Electric compressor

[0001] The present invention relates to an electric compressor.

[0002] Electric compressors with integrated inverters are known as electric compressors used to compress refrigerants in vehicle air conditioners, etc. In this type of electric compressor, the inverter includes multiple switching elements (e.g., IGBTs and power MOS transistors), each of which is fixed in place by screws.

[0003] JP 2003-322082 A JP 2020-198713 A

[0004] In recent years, the voltage input to switching elements has been increasing due to the increase in the capacity of electric compressors and the accompanying rise in rated power, etc. As a result, the temperature of switching elements has been increasing, and measures to address this trend are required.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electric compressor that can provide higher cooling performance for switching elements than conventional compressors.

[0006] According to one aspect of the present invention, there is provided a novel electric compressor. The electric compressor includes an electric motor that rotates a rotating shaft, a compression mechanism driven by the rotation of the rotating shaft, and an inverter that drives and controls the electric motor, the inverter being housed in an inverter housing. The inverter includes a plurality of switching elements that are fixed to an element mounting portion provided in the inverter housing by a pressing member. The pressing member has a plurality of fixing portions fixed to a mounting portion provided in the inverter housing and a plurality of pressing portions that each press one of the plurality of switching elements against the element mounting portion, and is made of a thermally conductive material.

[0007] According to the present invention, it is possible to provide an electric compressor that can obtain higher cooling performance for switching elements than conventional compressors.

[0008] It is a schematic cross-sectional view of an electric compressor according to an embodiment. It is a front view of a fixing structure of a switching element in the electric compressor. It is a plan view of a fixing structure of a switching element in the electric compressor. It is an exploded perspective view of a fixing structure of a switching element in the electric compressor. It is a plan view of another fixing structure of a switching element in the electric compressor.

[0009] 1 is a schematic cross-sectional view of an electric compressor 1 according to an embodiment of the present invention. The electric compressor 1 according to the embodiment is an inverter-integrated electric compressor having an inverter integrated therein. The electric compressor 1 is mounted on a vehicle, for example, to form part of a refrigerant circuit of an air conditioner for the vehicle, and is configured to compress and discharge refrigerant.

[0010] The electric compressor 1 includes a rotating shaft 2 , an electric motor 3 , a compression mechanism 4 , a main body housing 5 , an inverter 6 , an inverter housing 7 , and a cover member 8 .

[0011] The rotating shaft 2 is rotatably supported in a main housing 5 by bearings (not shown). The electric motor 3 is, for example, a three-phase synchronous motor, and is configured to be driven by power supplied from an inverter 6 to rotate the rotating shaft 2. The compression mechanism 4 is configured to be driven by the rotation of the rotating shaft 2 to compress the refrigerant. Although not particularly limited, the compression mechanism 4 may be a scroll compression mechanism. The main housing 5 is made of metal (for example, aluminum die-cast), has a cylindrical cross section, and accommodates the rotating shaft 2, the electric motor 3, and the compression mechanism 4 therein. Within the main housing 5, the electric motor 3 and the compression mechanism 4 are arranged in series.

[0012] The inverter 6 drives and controls the electric motor 3. The inverter housing 7 is integral with the main housing 5 and accommodates the inverter 6 therein. In this embodiment, the inverter housing 7 is provided at the end of the main housing 5 on the electric motor 3 side and has a larger projected area than the main housing 5. The inverter housing 7 is mainly formed by a bottom wall 71 and a peripheral wall 73 rising from the periphery of the bottom wall 71, and has an opening 75 facing the bottom wall 71. The opening 75 of the inverter housing 7 is closed by a cover member 8. The cover member 8 is fixed to the peripheral wall of the inverter housing 7 (which is also part of the main housing 5) with screws or the like (not shown).

[0013] A power connector (HV connector) 9 is fixed to the bottom wall 71 of the inverter housing 7 for supplying DC power from an on-board battery (not shown) serving as an external power source to the inverter 6. In other words, the power connector 9 electrically connects the on-board battery (external power source) to the inverter 6. In addition, a part of the bottom wall 71 of the inverter housing 7 forms a partition wall 77 that separates the inside of the main housing 5 from the inside of the inverter housing 7.

[0014] The main housing 5 is formed with an inlet 5a for allowing the refrigerant to flow into the main housing 5 and an outlet 5b for allowing the refrigerant to flow out of the main housing 5. The inlet 5a is configured to allow the refrigerant to flow into a space between the partition wall 77 and the electric motor 3 inside the main housing 5. The refrigerant that flows into the main housing 5 from the inlet 5a flows along the partition wall 77, passes through the electric motor 3, and reaches the compression mechanism 4, where it is compressed by the compression mechanism 4. The refrigerant compressed by the compression mechanism 4 then flows out from the outlet 5b.

[0015] The refrigerant flowing from the inlet 5 a into the main housing 5 is a low-temperature gas refrigerant. Therefore, the partition wall 77 (the bottom wall 71 of the inverter housing 7) and the electric motor 3 can be cooled by the refrigerant flowing from the inlet 5 a into the main housing 5.

[0016] The inverter 6 will now be described in further detail. The inverter 6 is configured to convert DC power supplied from the vehicle battery via a power connector 9 into three-phase AC power and supply it to the electric motor 3 via, for example, a power supply line 10 extending through a partition wall 77. The inverter 6 includes a plurality of switching elements, specifically six switching elements 61 (only one of which is shown in FIG. 1 ), and a circuit board 63 on which a control circuit 65 for controlling the operation of the six switching elements 61 is mounted. The switching elements 61 are power semiconductor switching elements such as IGBTs and power MOS transistors. In this embodiment, in addition to the control circuit 65, various circuit elements including a capacitor 67 and a coil (not shown) that constitute a noise filter are mounted on the circuit board 63.

[0017] The six switching elements 61 are fixed to an element mounting portion 79 provided in the inverter housing 7 by a presser member 20 (described later). The element mounting portion 79 is formed on the surface of the partition wall 77 facing the inverter housing 7, i.e., on the inner surface of the bottom wall 71 of the inverter housing 7 (the inner bottom surface of the inverter housing 7). Although not particularly limited, the element mounting portion 79 may be a machined surface of the inner surface of the bottom wall 71 of the inverter housing 7 (the inner bottom surface of the inverter housing 7). The element mounting portion 79 functions as a heat dissipation portion that dissipates heat from the six switching elements 61 by using the low-temperature gas refrigerant flowing into the main housing 5.

[0018] The circuit board 63 is fixed by screws 13 to the upper surfaces of a plurality of board mounting portions 11 provided inside the inverter housing 7. The board mounting portions 11 are formed to protrude from the inner surface of the bottom wall 71 of the inverter housing 7 (the inner bottom surface of the inverter housing 7). Therefore, in this embodiment, the circuit board 63 is disposed closer to the cover member 8 than the six switching elements 61 inside the inverter housing 7, that is, disposed away from the six switching elements 61 toward the cover member 8 (upward in FIG. 1 ).

[0019] Each of the six switching elements 61 has a lead 61 a extending toward the circuit board 63, and more specifically, a lead 61 a extending through the circuit board 63. These leads 61 a are then, for example, soldered to the circuit board 63, thereby electrically connecting the six switching elements 61 and the circuit board 63.

[0020] 2 to 4, a description will be given of a fixing structure for the switching element 61 of the inverter 6 in the electric compressor 1 according to this embodiment. Fig. 2 is a front view of the fixing structure for the switching element 61, Fig. 3 is a plan view of the fixing structure for the switching element 61, and Fig. 4 is an exploded perspective view of the fixing structure for the switching element 61.

[0021] As shown in FIGS. 2 to 4 , the fixing structure for the switching elements 61 includes a pressing member 20 for fixing the six switching elements 61 to an element mounting portion 79 provided in the inverter housing 7. The pressing member 20 is made of a thermally conductive material. Preferably, the pressing member 20 is formed in a plate shape from a metal material having spring properties. The pressing member 20 is disposed between the six switching elements 61 and the circuit board 63. When fixed in the inverter housing 7, the pressing member 20 presses the six switching elements 61 against the element mounting portion 79, fixing the six switching elements 61 to the element mounting portion 79.

[0022] In this embodiment, the six switching elements 61 are arranged in two rows of three on the element mounting portion 79 with their leads 61a facing inward, and are arranged in a rectangular shape as a whole in a plan view.

[0023] Correspondingly, the presser member 20 is also formed in a rectangular shape as a whole in a plan view. Specifically, the presser member 20 has a main body 21 that is rectangular in a plan view. The main body 21 of the presser member 20 is sized to accommodate the six switching elements 61 arranged in a rectangular shape in a plan view on the element mounting portion 79, i.e., large enough to cover the six switching elements 61 (it does not need to be large enough to cover them exactly, as long as it is large enough to generally cover the six switching elements 61). Furthermore, the main body 21 of the presser member 20 is formed with at least one opening for passing the leads 61 a of the six switching elements 61. In this embodiment, one opening 23 through which the leads 61 a of the six switching elements 61 can pass collectively is formed in approximately the center of the main body 21 of the presser member 20 in a plan view. However, this is not limited to this, and the main body 21 of the presser member 20 may be formed with multiple openings, each of which can pass a portion of the leads 61 a of the six switching elements 61.

[0024] Furthermore, the pressing member 20 has a plurality of (four in this example) fixing portions 25a to 25d for fixing the pressing member 20 itself (i.e., the pressing member 20) within the inverter housing 7. The four fixing portions 25a to 25d of the pressing member 20 are fixed by screws 17 to corresponding pressing member mounting portions 15a to 15d provided within the inverter housing 7. This fixes the pressing member 20 within the inverter housing 7, and thereby fixes the six switching elements 61 to the element mounting portions 79.

[0025] In this embodiment, the four pressing member mounting portions 15a to 15d are spaced apart from one another and surround the six switching elements 61 on the element mounting portion 79. Similar to the board mounting portion 11, the four pressing member mounting portions 15a to 15d are formed to protrude from the inner surface of the bottom wall 71 of the inverter housing 7 (the inner bottom surface of the inverter housing 7). Note that here, the four pressing member mounting portions 15a to 15d are formed on the element mounting portion 79. However, this is not limiting, and the four pressing member mounting portions 15a to 15d may be formed around the element mounting portion 79, or some of them may be formed on the element mounting portion 79 and the rest may be formed around the element mounting portion 79.

[0026] The four fixing portions 25a to 25d of the presser member 20 extend outward from the main body 21 so as to correspond to the four presser member mounting portions 15a to 15d, respectively. The four fixing portions 25a to 25d of the presser member 20 are fixed to the upper surfaces of the corresponding presser member mounting portions 15a to 15d with screws 17. Therefore, like the four presser member mounting portions 15a to 15d, the four fixing portions 25a to 25d of the presser member 20 are arranged spaced apart from one another so as to surround the six switching elements 61 in a plan view.

[0027] Specifically, in this embodiment, the four presser member mounting portions 15a to 15d provided within the inverter housing 7 are arranged at equal circumferential intervals (not necessarily at exact equal intervals, as long as they are approximately equal; the same applies below) so as to surround the six switching elements 61 on the element mounting portion 79. Correspondingly, the four fixing portions 25a to 25d of the presser member 20 are also arranged at equal circumferential intervals so as to surround the six switching elements 61 on the element mounting portion 79 in a plan view. Furthermore, each of the four fixing portions 25a to 25d of the presser member 20 extends outward from the center (not necessarily at the exact center, as long as it is approximately the center) of one of the four sides forming the outer edge of the main body portion 21 of the presser member 20. In this case, as shown in FIG. 3 , of the four fixing portions 25a to 25d of the presser member 20, the fixing portion 25a and the fixing portion 25b are arranged to face each other with two switching elements 61 interposed therebetween.

[0028] Furthermore, the pressing member 20 has six element pressing portions 27 (i.e., the same number as the switching elements 61). Each of the six element pressing portions 27 is provided in a portion of the main body 21 that is outside the opening 23, and protrudes downward. The six element pressing portions 27 of the pressing member 20 are configured to come into contact with the upper surface of one of the six switching elements 61 and press one of the six switching elements 61 against the element installation portion 79, by fixing each of the four fixing portions 25a to 25d of the pressing member 20 to the corresponding pressing member attachment portions 15a to 15d with screws 17.

[0029] In this embodiment, the "presser member mounting portions 15a to 15d" and the "element pressing portion 27" correspond to the "mounting portion" and the "pressing portion" of the present invention, respectively. Also, the fixing portion 25a and the fixing portion 25b correspond to the "pair of fixing portions" of the present invention.

[0030] According to the electric compressor 1 according to the embodiment, for example, the following effects can be obtained.

[0031] In the electric compressor 1 according to this embodiment, the multiple (six) switching elements 61 that make up the inverter 6 are fixed to an element mounting portion 79 provided within the inverter housing 7 by a presser member 20. The element mounting portion 79 functions as a heat dissipation portion. The presser member 20 is formed of a metallic material having spring properties, that is, a material having spring properties and good thermal conductivity. The presser member 20 is disposed between the six switching elements 61 and the circuit board 63. The presser member 20 has four fixing portions 25a to 25d that are fixed to four presser member mounting portions 15a to 15d provided within the inverter housing 7, and six element pressing portions 27 that each contact the top surface of one of the six switching elements 61 and press it against the element mounting portion 79.

[0032] The six switching elements 61 are pressed against the element mounting portion 79, which functions as a heat dissipation portion, by the six element pressing portions 27 of the pressing member 20, so that the heat of the six switching elements 61 can be stably dissipated. Furthermore, because the pressing member 20 is made of a material with good thermal conductivity, the heat of the six switching elements 61 can also be dissipated via the pressing member 20. Therefore, the electric compressor 1 according to this embodiment can achieve higher cooling performance for the switching elements 61 than conventional electric compressors.

[0033] The four fixing portions 25a to 25d of the pressing member 20 are arranged at a distance from one another so as to surround the six switching elements 61 on the element mounting portion 79. Specifically, the six switching elements 61 are arranged on the element mounting portion 79 in a rectangular shape as a whole in a plan view, and the pressing member 20 has a rectangular main body portion 21 having a size corresponding to the entire six switching elements 61 arranged on the element mounting portion 79, and openings 23 are formed in the main body portion 21 for passing the leads 61a of the six switching elements 61. The six element pressing portions 27 are provided on the main body portion 21, and each of the four fixing portions 25a to 25d extends outward from the center of one of the four sides forming the outer edge of the main body portion 21.

[0034] Therefore, the six switching elements 61 can be stably fixed by the pressing member 20, and the four fixing portions 25a to 25d are arranged in a balanced manner relative to the six element pressing portions 27, so that the heat of the six switching elements 61 can be stably dissipated through the four fixing portions 25a to 25d.

[0035] In the above-described embodiment, the presser member 20 has four fixing portions 25a to 25d, each of which extends outward from the center of one of the four sides forming the outer edge of the main body 21. However, this is not limited to this. For example, as shown in FIG. 5, the presser member 20 may have six fixing portions 25a to 25f (although not explicitly shown in FIG. 5, six pressing member mounting portions are also provided). In this case, as shown in FIG. 5, of the six fixing portions 25a to 25f, fixing portions 25a and 25b may be arranged to face each other across two switching elements 61 constituting different columns, fixing portions 25c and 25d may be arranged to face each other across three switching elements 61 constituting one column, and fixing portions 25e and 25f may be arranged to face each other across three switching elements 61 constituting another column.

[0036] Also, although not shown in the figure, a heat dissipation member (heat dissipation sheet) may be installed on the element installation portion 79, and the six element pressing portions 27 of the pressing member 20 may be configured to press the six switching elements 61 against the element installation portion 79 via the heat dissipation member (heat dissipation sheet).

[0037] The above describes the embodiments of the present invention and their modifications. However, the present invention is not limited to the above-described embodiments and modifications, and it goes without saying that further modifications are possible based on the technical concept of the present invention.

[0038] 1...electric compressor, 2...rotating shaft, 3...electric motor, 4...compression mechanism, 5...main body housing, 6...inverter, 7...inverter housing, 8...cover member, 11...board mounting portion, 15a to 15d...pressing member mounting portion (mounting portion), 20...pressing member, 21...main body portion, 23...opening, 25a to 25f...fixing portion, 27...element pressing portion (pressing portion), 61...switching element, 61a...lead, 63...circuit board

Claims

1. An electric compressor having an electric motor that rotates a rotating shaft, a compression mechanism driven by the rotation of the rotating shaft, and an inverter that drives and controls the electric motor, the inverter being housed in an inverter housing, wherein the inverter includes a plurality of switching elements, the plurality of switching elements being fixed to an element installation portion provided in the inverter housing by a pressing member, the pressing member having a plurality of fixing portions fixed to an attachment portion provided in the inverter housing and a plurality of pressing portions, each of which presses one of the plurality of switching elements against the element installation portion, and is formed of a thermally conductive material.

2. The electric compressor according to claim 1, wherein the inverter further includes a circuit board to which the multiple switching elements are electrically connected and on which a control circuit for controlling the operation of the multiple switching elements is mounted, and the pressing member is formed of a metallic material having spring properties and is disposed between the multiple switching elements and the circuit board.

3. The electric compressor according to claim 1 or 2, wherein the plurality of fixing portions of the pressing member are disposed apart from one another so as to surround the plurality of switching elements in a plan view.

4. The electric compressor as described in claim 3, wherein the multiple switching elements are arranged on the element mounting portion in a rectangular shape as a whole in a plan view, the pressing member has a rectangular main body portion having a size corresponding to the multiple switching elements as a whole and having at least one opening formed therein for passing leads of the multiple switching elements, the multiple pressing portions are provided on the main body portion, and each of the multiple fixing portions extends outward from one of four sides forming the outer edge of the main body portion.

5. The electric compressor according to claim 4, wherein each of said plurality of fixing portions extends outward from the center of any one of four sides forming the outer edge of said main body portion.

6. The electric compressor according to claim 4, wherein said plurality of fixing parts includes a pair of fixing parts arranged to sandwich at least two switching elements among said plurality of switching elements.

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