Electric compressor

Abstract

[Problem] To provide an electric compressor that improves cooling performance for switching elements of an inverter as compared to the prior art. [Solution] An electric compressor 1A is configured such that a through hole 54 is formed in an end wall 52 of an inverter case 5A that houses an inverter 13, and an outer surface of a front end wall 32 of a housing 3 that houses an electric motor 9 or the like and has an intake port 36 has an exposed part 35 that is exposed inside the inverter case 5A through the through hole 54. The inverter 13 includes: a plurality of switching elements 131 that are attached to the exposed part 35 via a heat dissipation sheet 21; and an electronic circuit board 132 that is attached to a board attachment part 55 of the inverter case 5A and has the plurality of switching elements 131 connected thereto.

Description

Electric compressor

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

[0002] As an example of a conventional electric compressor, the electric compressor described in Patent Document 1 includes a cylindrical discharge housing with a bottom, a cylindrical motor housing with a bottom connected to the discharge housing, and an inverter case connected to the motor housing. The motor housing houses a rotating shaft, a compression unit that compresses refrigerant by rotation of the rotating shaft, and an electric motor that rotates the rotating shaft. The inverter case includes a cylindrical case body with a bottom and a lid that closes an opening of the case body, and houses an inverter that drives the electric motor. The inverter has multiple switching elements. The inverter case is attached to the motor housing by connecting the bottom wall of the case body to the bottom wall of the motor housing.

[0003] In the electric compressor described in Patent Document 2, the compressor housing is divided by a partition wall into a space in which the electric motor and other components are disposed and an accommodation space in which the inverter is accommodated. The inverter's multiple power semiconductor elements (switching elements) are radially arranged around the drive shaft of the electric motor in a plane intersecting the drive shaft to suppress thermal interference between adjacent power semiconductor elements. The electric compressors described in Patent Documents 1 and 2 are used, for example, in vehicle air conditioning systems.

[0004] JP 2021-116787 A JP 2010-275951 A

[0005] With the recent trend toward electrification of automobiles, the applications of electric compressors mounted on automobiles have expanded. For example, electric compressors mounted on automobiles are now being used not only for cabin air conditioning but also for cooling on-board electronic devices such as batteries. As a result, the current flowing through switching elements of inverters has increased compared to conventional methods, resulting in increased heat generation from the switching elements, and measures to address this issue are being sought. Note that this need is not limited to electric compressors mounted on automobiles, but is also common to electric compressors that have an integrated inverter (i.e., inverter-integrated electric compressors).

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electric compressor that can improve the cooling performance of the switching elements of the inverter compared to the prior art.

[0007] According to one aspect of the present invention, there is provided an electric compressor. The electric compressor includes a housing that houses a rotating shaft, an electric motor that rotates the rotating shaft, and a compression mechanism that compresses fluid by rotation of the rotating shaft, and that has a suction port for introducing fluid into the housing. The inverter case is fixed to the housing so that an outer surface of an end wall of the inverter case is connected to an outer surface of an end wall of the housing. A through hole is formed in the end wall of the inverter case, and the outer surface of the end wall of the housing has an exposed portion that is exposed to the inside of the inverter case through the through hole. The inverter includes a plurality of switching elements attached to the exposed portion with a heat dissipation sheet interposed therebetween, and an electronic circuit board attached to a board mounting portion of the inverter case and to which the plurality of switching elements are connected.

[0008] According to one aspect of the present invention, it is possible to provide an electric compressor that can improve the cooling performance of a switching element of an inverter.

[0009] Fig. 1 is a cross-sectional view showing a schematic configuration of an electric compressor according to a first embodiment; Fig. 2 is a view corresponding to the AA end view of Fig. 1; Fig. 3 is a view showing a modified example of the electric compressor according to the first embodiment; Fig. 4 is a cross-sectional view showing a schematic configuration of an electric compressor according to a second embodiment; Fig. 5 is a view corresponding to the BB end view of Fig. 4; Fig. 6 is a view showing a modified example of the electric compressor according to the second embodiment;

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] [First Embodiment] Fig. 1 is a cross-sectional view showing a schematic configuration of an electric compressor according to a first embodiment of the present invention. The electric compressor 1A according to the first embodiment is mainly mounted on a vehicle such as an automobile. The electric compressor 1A is incorporated, for example, in a refrigerant circuit of a vehicle air conditioner and / or a vehicle battery cooling system, and is configured to compress, pressurize, and discharge a refrigerant (i.e., fluid) flowing through the refrigerant circuit. In the following description, the left side of Fig. 1 will be referred to as the front side of the electric compressor 1A, and the right side of Fig. 1 will be referred to as the rear side of the electric compressor 1A.

[0012] 1, the electric compressor 1A includes a housing 3 and an inverter case 5A. The inverter case 5A is disposed on the front side, and the housing 3 is disposed on the rear side.

[0013] The housing 3 has a cylindrical peripheral wall 31 extending in the front-rear direction, a front end wall 32 closing a front opening of the peripheral wall 31, and a rear end wall 33 closing a rear opening of the peripheral wall 31. The housing 3 accommodates the rotating shaft 7, the electric motor 9, and the compression mechanism 11. Although not particularly limited, in this embodiment, the compression mechanism 11 is a scroll compression mechanism, and the compression mechanism 11 has a fixed scroll 111 and a movable scroll 112.

[0014] The inverter case 5A is formed in a cylindrical shape with a bottom. The inverter case 5A has a cylindrical peripheral wall 51 extending in the front-to-rear direction and an end wall 52 that closes a rear opening of the peripheral wall 51. The inverter case 5A houses the inverter 13. The end wall 52 of the inverter case 5A may also be referred to as a bottom wall of the inverter case 5A. The opening of the inverter case 5A, i.e., the front opening of the peripheral wall 51, is closed by a cover member 53. The cover member 53 is detachable from the inverter case 5A and is fixed to the peripheral wall 51 of the inverter case 5A with bolts or the like (not shown).

[0015] The inverter case 5A is fixed to the housing 3 by bolts or the like (not shown) so that the outer surface of the end wall 52 of the inverter case 5A is connected to the outer surface of the front end wall 32 of the housing 3. Therefore, the front end wall 32 of the housing 3 corresponds to the "end wall of the housing" in the present invention. The outer surface of the end wall 52 of the inverter case 5A may also be referred to as the bottom surface of the inverter case 5A.

[0016] A through hole 54 is formed in the end wall 52 of the inverter case 5A. The front end wall 32 of the housing 3 has a protrusion 34 that fits into the through hole 54 formed in the end wall 52 of the inverter case 5A. The protrusion 34 has a shape corresponding to the through hole 54 and protrudes outward from the housing (forward in this case) beyond other portions of the front end wall 32. Although not particularly limited, in this embodiment, the through hole 54 is formed as a circular hole, and the protrusion 34 is formed in a cylindrical shape that corresponds to the through hole 54. Preferably, the protrusion 34 is formed in a hollow cylindrical shape with a closed tip.

[0017] The tip end surface of the protrusion 34 on the outer surface of the front end wall 32 of the housing 3 is exposed inside the inverter case 5A through the through hole 54. In other words, the outer surface of the front end wall 32 of the housing 3 has an exposed portion 35 (the tip end surface of the protrusion 34) exposed inside the inverter case 5A through the through hole 54.

[0018] In this embodiment, the entire or most of the exposed portion 35 is formed as a flat surface (it does not need to be strictly flat, as long as it is generally flat). The exposed portion 35 has an area equal to or greater than the cross-sectional area (transverse area) of the internal space of the housing 3. Furthermore, the exposed portion 35 is substantially flush with the area surrounding the through-hole 54 on the inner surface of the end wall 52 of the inverter case 5A.

[0019] The housing 3 will now be described in further detail.

[0020] In this embodiment, the housing 3 has, as housing components, a cylindrical motor housing 41 with a bottom and a cylindrical compressor housing 42 with a bottom. The housing 3 is formed by fastening the motor housing 41 and the compressor housing 42 together with bolts (not shown) or the like so that their open ends are joined together. The motor housing 41 is disposed on the front side, and the compressor housing 42 is disposed on the rear side. A seal (not shown) is interposed between the joined open ends of the motor housing 41 and the compressor housing 42, as needed.

[0021] Therefore, in this embodiment, the cylindrical peripheral wall of the motor housing 41 and the cylindrical peripheral wall of the compressor housing 42 form the peripheral wall 31 of the housing 3, the end wall of the motor housing 41 forms the front end wall 32 of the housing 3, and the end wall of the compressor housing 42 forms the rear end wall 33 of the housing 3. Furthermore, the exposed portion 35 has an area equal to or greater than the cross-sectional area (transverse area) of the internal space of the motor housing 41. The end walls of the motor housing 41 and the compressor housing 42 may also be referred to as the bottom wall of the motor housing 41 and the bottom wall of the compressor housing 42, respectively.

[0022] In this embodiment, the housing 3 further includes a partition member 43. The partition member is a member that divides the internal space of the housing 3, which is formed by the motor housing 41 and the compressor housing 42, into a front space and a rear space. The front space is the internal space of the motor housing 41, and the rear space is mainly the internal space of the compressor housing 42. The electric motor 9 is accommodated in the front space, i.e., the motor housing 41, and the compression mechanism 11 is accommodated in the rear space, i.e., the compressor housing 42.

[0023] Specifically, the partition member 43 is formed as a flanged, bottomed, cylindrical member and includes a cylindrical peripheral wall 431, an end wall 432 closing one end of the peripheral wall 431, and a flange 433 formed at the open end opposite the end wall 432. The end wall 432 of the partition member 43 may also be referred to as the bottom wall of the partition member 43. The partition member 43 is disposed at the rear side of the motor housing 41 with the end wall 432 facing forward. The peripheral edge of the flange 433 of the partition member 43, together with the peripheral edge of the fixed scroll 111 disposed in the compressor housing 42, is sandwiched between the motor housing 41 and the compressor housing 42. As a result, the partition member 43 is integrated with the motor housing 41 and the compressor housing 42, the fixed scroll 111 is fixed to the housing 3, and the partition member 43 divides the interior space of the housing 3 into the front space and the rear space. However, the front space and the rear space communicate with each other via a flange 433 of the partition member 43 and / or a communication passage 434 formed in the vicinity thereof.

[0024] The housing 3 also has a suction port 36 that introduces the refrigerant as a fluid (the refrigerant flowing through the refrigerant circuit) into the housing 3. In this embodiment, the suction port 36 is formed in a portion of the peripheral wall 31 of the housing 3 near the front end wall 32, i.e., in the motor housing 41.

[0025] Next, the rotating shaft 7, the electric motor 9, and the compression mechanism 11 housed in the housing 3 will be described.

[0026] The rotary shaft 7 extends in the front-rear direction within the housing 3. The rotary shaft 7 is rotatably supported by a front bearing 61 and a rear bearing 62. Although not particularly limited, in this embodiment, rolling bearings are used as the front bearing 61 and the rear bearing 62.

[0027] The front bearing 61 is held by the bearing holder 37. The bearing holder 37 is provided in approximately the center of the inner surface of the front end wall 32 of the housing 3. In other words, the bearing holder 37 is provided in a portion of the inner surface of the front end wall 32 of the housing 3 that is located inside the exposed portion 35. In this embodiment, the bearing holder 37 is formed in a cylindrical shape that protrudes inward from a portion of the inner surface of the front end wall 32 of the housing 3 that is located inside the exposed portion 35, and holds the front bearing 61 therein. The rear bearing 62 is held inside the peripheral wall 431 of the partition member 43.

[0028] That is, the housing 3 has a first bearing holder that holds a front bearing 61 that rotatably supports the rotary shaft 7, and a second bearing holder that holds a rear bearing 62 that rotatably supports the rotary shaft 7. The first bearing holder is a (cylindrical) bearing holder 37 that is provided in a portion that is located inside the exposed portion 35 on the inner surface of the front end wall 32 of the housing 3. The second bearing holder is a (cylindrical) peripheral wall 431 of the partition member 43 that divides the internal space of the housing 3 into the front space and the rear space.

[0029] In this embodiment, a shaft insertion hole (through hole) 435 through which the rotating shaft 7 can be inserted is formed approximately in the center of the end wall 432 of the partition member 43, and the rotating shaft 7 is rotatably supported by the front bearing 61 and the rear bearing 62 with its middle portion inserted into the shaft insertion hole 435.

[0030] In this embodiment, a shaft seal member 63 is provided to block communication between the front space and the rear space via the shaft insertion hole 435. The shaft seal member 63 is disposed inside the peripheral wall 431 of the partition member 43 and closer to the end wall 432 than the rear bearing 62. The shaft seal member 63 may be formed, for example, in an annular shape, and configured such that its outer periphery is fixed inside the peripheral wall 431 of the partition member 43 by, for example, press fitting, and its inner periphery is in contact (sliding contact) with the outer periphery of the rotating shaft 7.

[0031] The electric motor 9 is a three-phase AC motor and includes a stator 91 and a rotor 92. The stator 91 has a stator core and a stator winding. The stator 91 is fixed to the inner circumferential surface of the circumferential wall 31 of the housing 3 (the circumferential wall of the motor housing 41). The rotor 92 is disposed radially inward of the stator 91. A permanent magnet is incorporated into the rotor 92. The rotor 92 is formed in a cylindrical shape and is fixed to the rotating shaft 7 with the rotating shaft 7 inserted therethrough. The rotor 92 rotates integrally with the rotating shaft 7. When power is supplied from the inverter 13 to the stator 91 (stator winding), the electric motor 9 rotates the rotor 92, thereby rotating the rotating shaft 7. In other words, the electric motor 9 is configured to be driven by the inverter 13 to rotate the rotating shaft 7.

[0032] As described above, the compression mechanism 11 has the fixed scroll 111 and the movable scroll 112. The fixed scroll 111 has the first spiral wall 111a, and the movable scroll 112 has the second spiral wall 112a corresponding to the first spiral wall 111a. As described above, the fixed scroll 111 is fixed to the housing 3. The movable scroll 112 is disposed in front of the fixed scroll 111 so that the second spiral wall 112a meshes with the first spiral wall 111a of the fixed scroll 111.

[0033] The compression mechanism 11 is configured to compress refrigerant by driving the movable scroll 112 with the rotation of the rotary shaft 7. Specifically, the refrigerant is introduced into the housing 3 through the suction port 36, and then passes through a gap in the electric motor 9 and a communication passage 434 formed in the partition member 43 to reach the compression mechanism 11. In the compression mechanism 11, the rotation of the rotary shaft 7 is transmitted to the movable scroll 112 via the crank mechanism 81 to drive the movable scroll. The crank mechanism 81 converts the rotation of the rotary shaft 7 into orbital motion relative to the fixed scroll 111. The driven movable scroll 112 performs orbital motion relative to the fixed scroll 111 while its rotation is prevented by the rotation-preventing mechanism 83. The compression mechanism 11 then takes in and compresses the surrounding refrigerant as the movable scroll 112 orbits relative to the fixed scroll 111.

[0034] The refrigerant compressed in the compression mechanism 11 flows out from a discharge port 38. The discharge port 38 is formed in the compressor housing 42. More specifically, the refrigerant compressed in the compression mechanism 11 is discharged into a discharge chamber 87 formed in the compressor housing 42 through a discharge hole 111b formed in the fixed scroll 111 and a discharge reed valve 85 that opens and closes the discharge hole 111b, passes through an oil separator 89, and then flows out from the discharge port 38.

[0035] Next, the inverter 13 housed in the inverter case 5A will be described.

[0036] The inverter 13 drives the electric motor 9 by supplying power to the electric motor 9. The inverter 13 is configured to convert DC power from a DC power source such as an on-board battery (not shown) into AC power, and supply the converted AC power to (the stator winding of) a stator 91 of the electric motor 9 via a power supply line 15. The inverter 13 includes a plurality of (here, six) switching elements (e.g., IGBTs) 131 and an electronic circuit board 132 on which a control circuit for controlling the plurality of switching elements 131 and the like are mounted.

[0037] The multiple switching elements 131 are attached to the exposed portion 35 (the tip surface of the protrusion 34) on the outer surface of the front end wall 32 of the housing 3 with the elastic heat dissipation sheet 21 interposed therebetween. In other words, the heat dissipation sheet 21 is disposed between each of the multiple switching elements 131 and the exposed portion 35. In this embodiment, a sheet material that is elastic, has heat dissipation properties, and is insulating, is used as the heat dissipation sheet 21. Such a sheet material may be, for example, an insulating / heat dissipating sheet made of silicone.

[0038] In this embodiment, the multiple switching elements 131 are attached to the exposed portion 35 with pressing arms 22 as pressing members pressing against the heat dissipation sheet 21. The pressing arms 22 are fixed to arm mounting portions 39 formed on the exposed portion 35, for example, with bolts or the like (not shown).

[0039] The electronic circuit board 132 is attached to a board attachment portion 55 formed on the inverter case 5A with bolts or the like (not shown). In addition, leads 131a extending from each of the multiple switching elements 131 attached to the exposed portion 35 are connected to the electronic circuit board 132 by, for example, soldering.

[0040] FIG. 2 is a view corresponding to the AA end view of FIG. 1, and is a view mainly for explaining the positional relationship between the intake port 36 and the bearing holder 37 and the arrangement of the multiple switching elements 131.

[0041] 1 and 2 , in this embodiment, the suction port 36 is formed to guide the refrigerant into the housing 3 and direct the refrigerant toward the bearing holder 37. Specifically, the axis 36a of the suction port 36 faces the outer peripheral surface of the bearing holder 37.

[0042] Furthermore, the multiple (six) switching elements 131 are attached to the exposed portion 35 at a portion corresponding to the bearing holder 37 or in the vicinity thereof. More specifically, the multiple switching elements 131 are attached to the exposed portion 35 at intervals from one another so that all or most of them are located at the portion corresponding to the bearing holder 37 in the exposed portion 35 (see the dashed lines in FIG. 2).

[0043] The electric compressor 1A according to the first embodiment has the following advantages.

[0044] A through hole 54 is formed in the end wall 52 of the inverter case 5A, and the outer surface of the front end wall 32 of the housing 3 has an exposed portion 35 that is exposed to the inside of the inverter case 5A through the through hole 54. Specifically, the front end wall 32 of the housing 3 has a protrusion 34 that fits into the through hole 54, and the tip surface of the protrusion 34 forms the exposed portion 35. Furthermore, a plurality of switching elements 131 of the inverter 13 are attached to the exposed portion 35 with a heat dissipation sheet 21 interposed therebetween.

[0045] The refrigerant introduced into the housing 3 is a low-temperature refrigerant that has passed through the expansion valve and the evaporator in the refrigerant circuit. Therefore, the exposed portion 35 can be cooled by the refrigerant introduced into the housing 3. Furthermore, heat from the multiple switching elements 131 can be efficiently transferred to the exposed portion 35 via the heat dissipation sheet 21. Therefore, the electric compressor 1A according to this embodiment can improve the cooling performance of the multiple switching elements 131 compared to conventional electric compressors.

[0046] The multiple switching elements 131 are attached to the exposed portion 35 with the pressing arm 22, which serves as a pressing member, pressing against the heat dissipation sheet 21. This reduces the contact thermal resistance between the multiple switching elements 131 and the exposed portion 35, allowing the heat of the multiple switching elements 131 to be more efficiently transferred to the exposed portion 35. This can further improve the cooling performance of the multiple switching elements 131 in the electric compressor 1A.

[0047] The exposed portion 35 has an area equal to or larger than the cross-sectional area of ​​the internal space of the housing 3. Therefore, the exposed portion 35 can be effectively and stably cooled by the refrigerant introduced into the housing 3. Therefore, the cooling performance of the multiple switching elements 131 in the electric compressor 1A can be further improved.

[0048] The exposed portion 35 is substantially flush with the area surrounding the through-hole 54 on the inner surface of the end wall 52 of the inverter case 5A. Therefore, it is possible to easily attach the multiple switching elements 131 to the exposed portion 35 with the heat dissipation sheet 21 interposed therebetween.

[0049] A bearing holder 37 for holding a front bearing 61 that rotatably supports the rotating shaft 7 is provided in a portion of the inner surface of the front end wall 32 of the housing 3 that is located inside the exposed portion 35. A suction port 36 that guides refrigerant into the housing 3 is formed to direct the refrigerant toward the bearing holder 37. Specifically, the bearing holder 37 is formed cylindrically and protrudes from a portion of the inner surface of the front end wall 32 of the housing 3 that is located inside the exposed portion 35, and holds the front bearing 61 therein. The axis 36a of the suction port 36 faces the outer peripheral surface of the bearing holder 37. Furthermore, multiple switching elements 131 are attached to portions of the exposed portion 35 that correspond to or are near the bearing holder 37. Therefore, the portions of the exposed portion 35 where the multiple switching elements 131 are attached can be effectively cooled by the refrigerant guided into the housing 3. This further improves the cooling performance of the multiple switching elements 131 in the electric compressor 1A.

[0050] In the above embodiment, the through hole 54 in the end wall 52 of the inverter case 5A is formed as a circular hole, and the protrusion 34 on the front end wall 32 of the housing 3 is formed as a cylinder corresponding to the through hole 54. However, this is not limited to this. The through hole 54 and the protrusion 34 may have any shape. For example, the through hole 54 may be formed as a rectangular hole, and the protrusion 34 may be formed as a rectangular pillar corresponding to the through hole 54, preferably as a hollow rectangular pillar with a closed tip.

[0051] In the above-described embodiment, the exposed portion 35 has an area equal to or larger than the cross-sectional area (transverse area) of the interior space of the housing 3 (motor housing 41). However, this is not limited to this. It is sufficient that the exposed portion 35 can be sufficiently cooled by the refrigerant introduced into the housing 3. For example, the exposed portion 35 may have an area equal to or larger than half the cross-sectional area (transverse area) of the interior space of the housing 3 (motor housing 41).

[0052] In the above embodiment, the exposed portion 35 is generally flush with the area surrounding the through-hole 54 on the inner surface of the end wall 52 of the inverter case 5A. However, this is not limiting. The exposed portion 35 may be recessed or protruded from the area surrounding the through-hole 54 on the inner surface of the end wall 52 of the inverter case 5A.

[0053] In the above-described embodiment, the multiple switching elements 131 are attached to the exposed portion 35 with each of them pressing the heat dissipation sheet 21 with the pressing arm 22 serving as a pressing member. However, this is not limited to this. The multiple switching elements 131 may be attached to the exposed portion 35 by any means while pressing the heat dissipation sheet 21. For example, the multiple switching elements 131 may be integrated (modularized) with synthetic resin (preferably insulating resin) and attached to the exposed portion 35 as a single switching element module. In this case, the switching element module may be attached to the exposed portion 35 with the pressing member pressing the heat dissipation sheet 21, or the switching element module may be attached to the exposed portion 35 with the heat dissipation sheet 21 interposed therebetween using a fastening member such as a bolt.

[0054] In the above embodiment, the tip surface of the protrusion 34 of the front end wall 32 of the housing 3, which is fitted into the through hole 54 formed in the end wall 52 of the inverter case 5A, forms the exposed portion 35. However, this is not limited to this. As shown in FIG. 3 , a part of the flat outer surface of the front end wall 32 of the housing 3 may form the exposed portion 35. In this case, the multiple switching elements 131 are disposed outside the inner surface of the end wall 52 of the inverter case 5A, in other words, inside the through hole 54 formed in the end wall 52 of the inverter case 5A.

[0055] [Second Embodiment] Fig. 4 is a cross-sectional view showing a schematic configuration of an electric compressor according to a second embodiment of the present invention. The electric compressor 1B according to the second embodiment is mainly mounted on a vehicle such as an automobile. The electric compressor 1B is incorporated, for example, in a refrigerant circuit of a vehicle air conditioner and / or a vehicle battery cooling system, and is configured to compress, pressurize, and discharge a refrigerant (i.e., fluid) flowing through the refrigerant circuit. In the following description, the left side of Fig. 1 will be referred to as the front side of the electric compressor 1B, and the right side of Fig. 1 will be referred to as the rear side of the electric compressor 1B.

[0056] Referring to FIG. 4, the electric compressor 1B has a housing 3 and an inverter accommodating portion 5B.

[0057] The housing 3 has a cylindrical cross section and extends in the front-rear direction. The housing 3 accommodates the rotating shaft 7, the electric motor 9, and the compression mechanism 11. Although not particularly limited, in this embodiment, the compression mechanism 11 is a scroll compression mechanism, and the compression mechanism 11 has a fixed scroll 111 and a movable scroll 112.

[0058] The inverter accommodating section 5B is disposed at the front end of the housing 3 and is provided integrally with the housing 3. The inverter accommodating section 5B is formed in a cylindrical shape with a bottom and includes a cylindrical peripheral wall 51 extending in the front-to-rear direction and an end wall 52 closing a rear opening, which is one opening of the peripheral wall. The inverter accommodating section 5B accommodates the inverter 13. The end wall 52 of the inverter accommodating section 5B may also be referred to as the bottom wall of the inverter accommodating section 5B. The opening of the inverter accommodating section 5B, i.e., the front opening, which is the other opening of the peripheral wall 51, is closed by a cover member 53. The cover member 53 is detachable from the inverter accommodating section 5B and is fixed to the peripheral wall 51 of the inverter accommodating section 5B with bolts or the like (not shown).

[0059] In this embodiment, when viewed from the front (or rear), (the end wall 52 of) the inverter accommodating portion 5B is formed to be larger than the outer shape of the housing 3. A part of the end wall 52 of the inverter accommodating portion 5B forms a partition wall 6 that separates the interior of the housing 3 from the interior of the inverter accommodating portion 5B.

[0060] The housing 3 will now be described in further detail.

[0061] In this embodiment, the housing 3 has a motor housing 41 and a compressor housing 42 as housing components. The housing 3 is formed by fastening the motor housing 41 and the compressor housing 42 together with bolts (not shown) or the like. The motor housing 41 is disposed on the front side, and the compressor housing 42 is disposed on the rear side. A sealant (not shown) is interposed at the joint between the motor housing 41 and the compressor housing 42, as necessary. The inverter accommodating section 5B is provided integrally with the motor housing 41, and the partition wall 6 separates the interior of the motor housing 41 from the interior of the inverter accommodating section 5B.

[0062] The housing 3 further includes a partition member 43. The partition member 43 is a member that divides the internal space of the housing 3, which is formed by the motor housing 41 and the compressor housing 42, into a front space and a rear space. The front space is the internal space of the motor housing 41, and the rear space is mainly the internal space of the compressor housing 42. The electric motor 9 is accommodated in the front space, i.e., the motor housing 41, and the compression mechanism 11 is accommodated in the rear space, i.e., the compressor housing 42.

[0063] Specifically, the partition member 43 is formed as a flanged, bottomed, cylindrical member and includes a cylindrical peripheral wall 431, an end wall 432 closing one end of the peripheral wall 431, and a flange 433 formed at the open end opposite the end wall 432. The end wall 432 of the partition member 43 may also be referred to as the bottom wall of the partition member 43. The partition member 43 is disposed at the rear side of the motor housing 41 with the end wall 432 facing forward. The peripheral edge of the flange 433 of the partition member 43, together with the peripheral edge of the fixed scroll 111 disposed in the compressor housing 42, is sandwiched between the motor housing 41 and the compressor housing 42. As a result, the partition member 43 is integrated with the motor housing 41 and the compressor housing 42, the fixed scroll 111 is fixed to the housing 3, and the partition member 43 divides the interior space of the housing 3 into the front space and the rear space. However, the front space and the rear space communicate with each other via a flange 433 of the partition member 43 and / or a communication passage 434 formed in the vicinity thereof.

[0064] The housing 3 also has a suction port 36 that introduces the refrigerant as a fluid (the refrigerant flowing through the refrigerant circuit) into the housing 3. In this embodiment, the suction port 36 is formed near the partition wall 6 in the peripheral wall 31 of the housing 3, i.e., in the motor housing 41.

[0065] Next, the rotating shaft 7, the electric motor 9, and the compression mechanism 11 housed in the housing 3 will be described.

[0066] The rotary shaft 7 extends in the front-rear direction within the housing 3. The rotary shaft 7 is rotatably supported by a front bearing 61 and a rear bearing 62. Although not particularly limited, in this embodiment, rolling bearings are used as the front bearing 61 and the rear bearing 62.

[0067] The front bearing 61 is held by the bearing holder 37. The bearing holder 37 is provided approximately in the center of the surface 6a of the partition wall 6 facing the inside of the housing 3 (the inside of the motor housing 41) (hereinafter referred to as the "first surface 6a of the partition wall 6"). In this embodiment, the bearing holder 37 is formed in a cylindrical shape that protrudes from the first surface 6a of the partition wall 6 toward the inside of the housing, and holds the front bearing 61 therein. The rear bearing 62 is held inside the peripheral wall 431 of the partition wall member 43.

[0068] That is, the housing 3 has a first bearing holder that holds a front bearing 61 that rotatably supports the rotary shaft 7, and a second bearing holder that holds a rear bearing 62 that rotatably supports the rotary shaft 7. The first bearing holder is a (cylindrical) bearing holder 37 provided on the first surface 6a of the partition wall 6. The second bearing holder is a (cylindrical) peripheral wall 431 of the partition wall member 43 that divides the internal space of the housing 3 into the front space and the rear space.

[0069] Here, in this embodiment, a shaft insertion hole (through hole) 435 into which the rotating shaft 7 can be inserted is formed in the end wall 432 of the partition member 43, and the rotating shaft 7 is rotatably supported by the front bearing 61 and the rear bearing 62 with its middle portion inserted into the shaft insertion hole 435.

[0070] In this embodiment, a shaft seal member 63 is provided to block communication between the front space and the rear space via the shaft insertion hole 435. The shaft seal member 63 is disposed inside the peripheral wall 431 of the partition member 43 and closer to the end wall 432 than the rear bearing 62. The shaft seal member 63 may be formed, for example, in an annular shape, and configured such that its outer periphery is fixed inside the peripheral wall 431 of the partition member 43 by, for example, press fitting, and its inner periphery is in contact (sliding contact) with the outer periphery of the rotating shaft 7.

[0071] The electric motor 9 is a three-phase AC motor and includes a stator 91 and a rotor 92. The stator 91 has a stator core and stator windings. The stator 91 is fixed to the inner circumferential surface of the circumferential wall 31 of the housing 3 (the circumferential wall of the motor housing 41). The rotor 92 is disposed radially inward of the stator 91. A permanent magnet is incorporated into the rotor 92. The rotor 92 is formed in a cylindrical shape and is fixed to the rotating shaft 7 with the rotating shaft 7 inserted therethrough. In other words, the rotor 92 rotates integrally with the rotating shaft 7. In the electric motor 9, the rotor 92 rotates when power is supplied from the inverter 13 to the stator 91 (stator windings), thereby rotating the rotating shaft 7. In other words, the electric motor 9 is configured to be driven by the inverter 13 to rotate the rotating shaft 7.

[0072] As described above, the compression mechanism 11 has the fixed scroll 111 and the movable scroll 112. The fixed scroll 111 has the first spiral wall 111a, and the movable scroll 112 has the second spiral wall 112a corresponding to the first spiral wall 111a. As described above, the fixed scroll 111 is fixed to the housing 3. The movable scroll 112 is disposed in front of the fixed scroll 111 so that the second spiral wall 112a meshes with the first spiral wall 111a of the fixed scroll 111.

[0073] The compression mechanism 11 is configured to compress refrigerant by driving the movable scroll 112 with the rotation of the rotary shaft 7. Specifically, the refrigerant is introduced into the housing 3 through the suction port 36, and then passes through a gap in the electric motor 9 and a communication passage 434 formed in the partition member 43 to reach the compression mechanism 11. In the compression mechanism 11, the rotation of the rotary shaft 7 is transmitted to the movable scroll 112 via the crank mechanism 81 to drive the movable scroll. The crank mechanism 81 converts the rotation of the rotary shaft 7 into orbital motion relative to the fixed scroll 111. The driven movable scroll 112 performs orbital motion relative to the fixed scroll 111 while its rotation is prevented by the rotation-preventing mechanism 83. The compression mechanism 11 then takes in and compresses the surrounding refrigerant as the movable scroll 112 orbits relative to the fixed scroll 111.

[0074] The refrigerant compressed in the compression mechanism 11 flows out from a discharge port 38. The discharge port 38 is formed in the compressor housing 42. More specifically, the refrigerant compressed in the compression mechanism 11 is discharged into a discharge chamber 87 formed in the compressor housing 42 through a discharge hole 111b formed in the fixed scroll 111 and a discharge reed valve 85 that opens and closes the discharge hole 111b, passes through an oil separator 89, and then flows out from the discharge port 38.

[0075] Next, the inverter 13 accommodated in the inverter accommodating section 5B will be described.

[0076] The inverter 13 drives the electric motor 9 by supplying power to the electric motor 9. The inverter 13 is configured to convert DC power from a DC power source such as an on-board battery (not shown) into AC power, and supply the converted AC power to (the stator winding of) a stator 91 of the electric motor 9 via a power supply line 15. The inverter 13 includes a plurality of (here, six) switching elements (e.g., IGBTs) 131 and an electronic circuit board 132 on which a control circuit for controlling the plurality of switching elements 131 and the like are mounted.

[0077] The multiple switching elements 131 are arranged on the surface of the partition wall 6 opposite the first surface 6a, i.e., on the surface 6b of the partition wall 6 facing the inside of the inverter accommodating section 5B (hereinafter referred to as the "second surface 6b of the partition wall 6"). Specifically, the multiple switching elements 131 are attached to the second surface 6b of the partition wall 6 with an elastic heat dissipation sheet 21 interposed therebetween. In other words, the heat dissipation sheet 21 is arranged between the multiple switching elements 131 and the second surface 6b of the partition wall 6. In this embodiment, a sheet material that is elastic, heat dissipating, and insulating is used as the heat dissipation sheet 21. Such a sheet material may be, for example, an insulating and heat dissipating sheet made of silicone.

[0078] In this embodiment, the multiple switching elements 131 are attached to the second surface 6 b of the partition wall 6 by pressing arms 22 as pressing members, each pressing against the heat dissipation sheet 21. The pressing arms 22 are fixed to arm mounting portions 39 formed on the second surface 6 b of the partition wall 6, for example, by bolts or the like (not shown).

[0079] The electronic circuit board 132 is attached to a board attachment portion 55 formed in the inverter accommodating portion 5B with bolts or the like (not shown). In addition, leads 131 a extending from each of the multiple switching elements 131 attached to the second surface 6 b of the partition wall 6 are connected to the electronic circuit board 132 by, for example, soldering.

[0080] FIG. 5 is a view corresponding to the BB end view of FIG. 4, and is a view mainly for explaining the positional relationship between the intake port 36 and the bearing holder 37 and the arrangement of the multiple switching elements 131.

[0081] 4 and 5 , in this embodiment, the suction port 36 is formed to guide the refrigerant into the housing 3 and direct the refrigerant toward the bearing holder 37. Specifically, the axis 36a of the suction port 36 faces the outer peripheral surface of the bearing holder 37. In other words, (an extension of) the axis 36a of the suction port 36 intersects with the outer peripheral surface of the bearing holder 37. Preferably, the axis 36a of the suction port 36 faces the rotation shaft 7.

[0082] The multiple (six) switching elements 131 are arranged at intervals from one another at or near the portion of the second surface 6b of the partition wall 6 that corresponds to the bearing holder 37, which is the surface opposite to the first surface 6a (see the dashed lines in FIG. 2). More specifically, the multiple switching elements 131 are attached to the second surface 6b of the partition wall 6 at or near the portion that corresponds to the bearing holder 37, with the heat dissipation sheet 21 interposed therebetween, and each of the multiple switching elements 131 presses against the heat dissipation sheet 21.

[0083] The electric compressor 1B according to the second embodiment provides the following effects.

[0084] The interior of the housing 3 and the interior of the inverter accommodating section 5B are separated by a partition wall 6, and a first surface 6a of the partition wall 6 facing the interior of the housing 3 is provided with a bearing holder 37 that holds a front bearing 61 that rotatably supports the rotating shaft 7. Furthermore, a suction port 36 that introduces refrigerant into the housing 3 is formed to direct the refrigerant toward the bearing holder 37. Specifically, the bearing holder 37 is formed to protrude cylindrically from the first surface 6a of the partition wall 6 and holds the front bearing 61 therein, and the axis 36a of the suction port 36 faces the outer peripheral surface of the bearing holder 37. Furthermore, a plurality of switching elements 131 are arranged in a portion of a second surface 6b of the partition wall 6 opposite the first surface 6a, corresponding to or in the vicinity of the bearing holder 37.

[0085] The refrigerant introduced into the housing 3 is a low-temperature refrigerant that has passed through the expansion valve and the evaporator in the refrigerant circuit. Therefore, the refrigerant introduced into the housing 3 intensively cools the bearing holder 37 and its surroundings, and ultimately the portion of the second surface 6b of the partition wall 6 that corresponds to the bearing holder 37 and its vicinity. In other words, the portion where the multiple switching elements 131 are arranged can be intensively cooled. Therefore, the electric compressor 1B according to this embodiment can improve the cooling performance of the multiple switching elements 131 compared to conventional electric compressors.

[0086] The multiple switching elements 131 are attached to the second surface 6 b of the partition wall 6 at a portion corresponding to the bearing holder 37 or in the vicinity thereof, with the heat dissipation sheet 21 interposed therebetween. Therefore, heat from the multiple switching elements 131 is efficiently conducted to the portion corresponding to the bearing holder 37 on the second surface 6 b of the partition wall 6, where the refrigerant can cool the refrigerant intensively, or in the vicinity thereof. Therefore, the cooling performance of the multiple switching elements 131 in the electric compressor 1B can be further improved.

[0087] In particular, the multiple switching elements 131 are attached to the second surface 6 b of the partition wall 6 at or near the portion corresponding to the bearing holder 37 with the heat dissipation sheet 21 pressed against it. This reduces the occurrence of contact thermal resistance, and more efficiently transfers heat from the multiple switching elements 131 to the second surface 6 b of the partition wall 6 at or near the portion corresponding to the bearing holder 37, where the heat can be intensively cooled by the refrigerant. This further improves the cooling performance of the multiple switching elements 131 in the electric compressor 1B.

[0088] In the above embodiment, a part of the end wall 52 of the inverter accommodating portion 5B forms the partition wall 6. However, this is not limited to this, and the partition wall 6 may be any wall that separates the interior of the housing 3 (the interior of the motor housing 41) from the interior of the inverter accommodating portion 5B. For example, the entire end wall 52 of the inverter accommodating portion 5B or the entire or part of the end wall of the housing 3 may form the partition wall 6.

[0089] Furthermore, in the above-described embodiment, the multiple switching elements 131 are attached to the portion of the second surface 6 b of the partition wall 6 corresponding to the bearing holder 37 or in the vicinity thereof, with the heat dissipation sheet 21 pressed by the pressing arm 22 serving as a pressing member. However, this is not limited to this. For example, the multiple switching elements 131 may be integrated (modularized) using synthetic resin (preferably insulating resin) and attached as a single switching element module to the portion of the second surface 6 b of the partition wall 6 corresponding to the bearing holder 37 or in the vicinity thereof. In this case, the switching element module is attached to the portion of the second surface 6 b of the partition wall 6 corresponding to the bearing holder 37 or in the vicinity thereof, with the heat dissipation sheet 21 pressed by the pressing member, or the switching element module is attached to the portion of the second surface 6 b of the partition wall 6 corresponding to the bearing holder 37 or in the vicinity thereof, with the heat dissipation sheet 21 interposed therebetween, using fastening members such as bolts.

[0090] Alternatively, an arc-shaped rib 14 may be formed on the first surface 6a of the partition wall 6, surrounding a portion of the bearing holder 37. In this case, as shown in FIG. 6 , which corresponds to FIG. 5 , the arc-shaped rib 14 is formed to protrude from the first surface 6a of the partition wall 6 toward the inside of the housing so as to surround a portion of the outer circumferential surface of the bearing holder 37 excluding a predetermined area on the suction port 36 side of the outer circumferential surface of the bearing holder 37. The distance between the arc-shaped rib 14 and the outer circumferential surface portion of the bearing holder 37 may be set arbitrarily. Furthermore, the arc-shaped rib 14 has a protruding height that is at least half the protruding height of the bearing holder 37. Preferably, the arc-shaped rib 14 has a protruding height that is the same as the protruding height of the bearing holder 37 (it does not need to be exactly the same, as long as it is approximately the same). The protruding height of the bearing holding portion 37 refers to the distance from the first surface 6a of the partition wall 6 to the tip of the bearing holding portion 37, and the protruding height of the arc-shaped rib 14 refers to the distance from the first surface 6a of the partition wall 6 to the tip of the arc-shaped rib 14.

[0091] In this manner, the arc-shaped rib 14, the outer peripheral surface of the bearing retainer 37, and the first surface 6a of the partition wall 6 form a flow path through which the refrigerant flows along the outer peripheral surface of the bearing retainer 37 and the portion of the first surface 6a of the partition wall 6 surrounding the bearing retainer 37. This also suppresses the diffusion of refrigerant that strikes the outer peripheral surface of the bearing retainer 37. This allows for more intensive and efficient cooling of the bearing retainer 37 and its surroundings, as well as the portion of the second surface 6b of the partition wall 6 corresponding to the bearing retainer 37 and its vicinity, i.e., the portion where the multiple switching elements 131 are disposed. This further improves the cooling performance of the multiple switching elements 131 in the electric compressor 1B. Note that the arc-shaped rib 14 may be formed on the inner surface of the front end wall 32 of the housing 3 in the first embodiment.

[0092] The above describes the embodiments and modifications of the present invention, but the present invention is not limited to the above-described embodiments and modifications, and it goes without saying that further modifications and changes are possible based on the technical concept of the present invention.

[0093] Examples of clauses that can be understood from the first embodiment and its modifications are listed below.

[0094] [Clause 1] An electric compressor comprising: a housing that houses a rotating shaft, an electric motor that rotates the rotating shaft, and a compression mechanism that compresses fluid by rotation of the rotating shaft, and that has a suction port that guides fluid into the housing; and an inverter case that houses an inverter that drives the electric motor, wherein the inverter case is fixed to the housing so that outer surfaces of end walls of the inverter case and the housing are connected to each other; wherein a through hole is formed in the end wall of the inverter case, and the outer surface of the end wall of the housing has an exposed portion that is exposed to the inside of the inverter case through the through hole; and the inverter includes a plurality of switching elements attached to the exposed portion with a heat dissipation sheet interposed therebetween, and an electronic circuit board that is attached to a board mounting portion of the inverter case and to which the plurality of switching elements are connected.

[0095] [Clause 2] The electric compressor according to clause 1, wherein the plurality of switching elements are attached to the exposed portion in a state where they press against the heat dissipation sheet.

[0096] [Clause 3] The electric compressor according to clause 1 or 2, wherein the exposed portion has an area equal to or greater than half of a cross-sectional area of ​​the internal space of the housing.

[0097] [Clause 4] The electric compressor according to any one of clauses 1 to 3, wherein the end wall of the housing has a protrusion that is fitted into the through hole formed in the end wall of the inverter case, and a tip surface of the protrusion forms the exposed portion.

[0098] [Clause 5] The electric compressor according to Clause 4, wherein the exposed portion is substantially flush with a portion of the inner surface of the end wall of the inverter case surrounding the through hole.

[0099] [Clause 6] The electric compressor according to any one of Clauses 1 to 5, wherein a bearing holding portion that holds a bearing that rotatably supports the rotating shaft is provided in a portion located inside the exposed portion on the inner surface of the end wall of the housing, the suction port is formed to direct fluid to the bearing holding portion, and the plurality of switching elements are attached to a portion of the exposed portion that corresponds to the bearing holding portion or in the vicinity thereof.

[0100] [Clause 7] The electric compressor according to Clause 6, wherein the bearing holder is formed to protrude cylindrically from a portion of the inner surface of the end wall of the housing that is located inside the exposed portion, and holds the bearing therein, and the axis of the suction port faces an outer peripheral surface of the bearing holder.

[0101] [Clause 8] The electric compressor according to any one of Clauses 1 to 7, wherein the housing includes a motor housing as a housing component that houses the electric motor and has the suction port, and an end wall of the motor housing forms the end wall of the housing.

[0102] Examples of clauses that can be understood from the second embodiment and its modifications are listed below.

[0103] [Clause 9] An electric compressor comprising: a housing that accommodates a rotating shaft, an electric motor that rotates the rotating shaft, and a compression mechanism that compresses fluid by rotation of the rotating shaft, and that has an intake port that guides fluid into its interior; an inverter that drives the electric motor; and an inverter accommodating section that is formed integrally with the housing and accommodates the inverter, wherein the interior of the housing and the interior of the inverter accommodating section are separated by a partition wall, wherein a bearing holding section that holds a bearing that rotatably supports the rotating shaft is provided on a first surface of the partition wall that faces the interior of the housing, the suction port is formed to direct fluid toward the bearing holding section, and a plurality of switching elements that constitute the inverter are arranged in a portion that corresponds to or near the bearing holding section on a second surface of the partition wall that is on the opposite side to the first surface and faces the interior of the inverter accommodating section.

[0104] [Clause 10] The electric compressor according to Clause 9, wherein the bearing holder is formed to protrude cylindrically from the first surface of the partition wall and holds the bearing therein, and an axis of the suction port faces an outer peripheral surface of the bearing holder.

[0105] [Clause 11] The electric compressor according to Clause 10, wherein an arc-shaped rib is formed on the first surface of the partition wall so as to protrude and surround an outer peripheral surface of the bearing holder except for a predetermined range on the suction port side.

[0106] [Clause 12] The electric compressor according to Clause 11, wherein the arc-shaped rib has a protruding height that is equal to or greater than half the protruding height of the bearing holder.

[0107] [Clause 13] The electric compressor according to any one of Clauses 9 to 12, wherein the inverter accommodating section includes a cylindrical peripheral wall and an end wall that closes one opening of the peripheral wall, and a part of the end wall forms the partition wall.

[0108] [Clause 14] The electric compressor according to any one of Clauses 9 to 13, wherein the plurality of switching elements are attached to a portion of the second surface of the partition wall that corresponds to the bearing holder or in the vicinity thereof, with a heat dissipation sheet interposed therebetween.

[0109] [Clause 15] The electric compressor according to any one of Clauses 9 to 14, wherein the housing includes a motor housing as a housing component that houses the electric motor and has the suction port, and an end wall of the motor housing forms the end wall of the housing.

[0110] 1A, 1B...electric compressor, 3...housing, 5A...inverter case, 5B...inverter accommodating section, 6...partition wall, 7...rotating shaft, 9...electric motor, 11...compression mechanism, 13...inverter, 21...heat dissipation sheet, 32...front end wall (end wall of housing), 34...projection portion, 35...exposed portion, 36...suction port, 36a...axis of suction port, 37...bearing holding section, 41...motor housing, 51...circumferential wall (circumferential wall of inverter case, inverter accommodating section), 52...end wall (end wall of inverter case, inverter accommodating section), 53...cover member, 54...through hole, 55...board mounting section, 61...front bearing (bearing), 131...switching element, 132...electronic circuit board

Claims

1. An electric compressor comprising: a housing which houses a rotating shaft, an electric motor which rotates the rotating shaft, and a compression mechanism which compresses fluid by rotation of the rotating shaft, and which has a suction port which guides the fluid into its interior; and an inverter case which houses an inverter which drives the electric motor, the inverter case being fixed to the housing such that an outer surface of an end wall of the inverter case is connected to an outer surface of an end wall of the housing, wherein a through hole is formed in the end wall of the inverter case, and the outer surface of the end wall of the housing has an exposed portion which is exposed to the inside of the inverter case through the through hole, and the inverter includes a plurality of switching elements which are attached to the exposed portion with a heat dissipation sheet interposed therebetween, and an electronic circuit board which is attached to a board mounting portion of the inverter case and to which the plurality of switching elements are connected.

2. The electric compressor according to claim 1, wherein the plurality of switching elements are attached to the exposed portion in a state in which the heat dissipation sheet is pressed against the exposed portion.

3. The electric compressor according to claim 1, wherein the exposed portion has an area equal to or greater than half the cross-sectional area of ​​the internal space of the housing.

4. The electric compressor according to claim 1, wherein the end wall of the housing has a protrusion that fits into the through hole formed in the end wall of the inverter case, and a tip surface of the protrusion forms the exposed portion.

5. The electric compressor according to claim 4, wherein the exposed portion is substantially flush with a portion of the inner surface of the end wall of the inverter case surrounding the through hole.

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