Electric compressor

Abstract

To improve heat radiation performance and insulation performance of a drive circuit which drives an electric motor.SOLUTION: An inverter for driving an electric motor is installed in a housing which houses a compression mechanism and the electric motor serving as a power source of the compression mechanism to form an inverter integrated electric compressor. In the inverter integrated electric compressor, an installation object surface 361 of a package 100 including a switching element 41 of the inverter in a second partition wall 36 is provided as a bottom surface of a recessed part 364 formed at the second partition wall 36. A screw part of a bolt 110 inserted into a bolt insertion hole 100C of the package 100 is screwed into a screw hole formed on the installation object surface 361 of the second partition wall 36 to fix the package 100, and the recessed part 364 is filled with a sealant.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an electric compressor in which a drive circuit for driving an electric motor is installed in a housing that accommodates a compression mechanism and an electric motor that is a power source for the compression mechanism, and the drive circuit is integrated into the housing. [Background technology]

[0002] As described in Patent Document 1, for example, a known electric compressor has a package containing inverter switching elements. The package is secured to the base plate by inserting bolts into bolt holes formed in the package and screwing the bolts into the base plate. An insulating sheet with good thermal conductivity is interposed between the base plate and an electrically conductive heat sink provided on the bottom surface of the package to promote heat dissipation from the heat sink and suppress discharge. To increase the insulation distance from the heat sink to the bolts, an insulating member is provided. The insulating member is a cylindrical member extending from a base body disposed in a groove in the base plate and sandwiched between the insulating sheet and the bottom surface of the groove by the pressing force of the bolts when the bolts are screwed into the base plate, along the bolt threads, to the inside of the bolt insertion hole in the package. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-198713 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, electric compressors used in the refrigeration cycle of vehicle air conditioners are being required to support high voltages, for example, 800 V or higher, in order to accommodate rapid charging associated with the large-capacity batteries of electric vehicles, improve output density, reduce losses, etc. Therefore, there is a demand for stronger heat dissipation and insulation performance in inverters than ever before.

[0005] However, in the electric compressor described in Patent Document 1, the pressing force when the bolts are screwed is limited by the allowable mechanical stress of the switching elements, and the dimensions of the insulating member, bolt insertion hole, and groove usually include manufacturing tolerances. Therefore, very small gaps may occur between the insulating sheet and the heat sink / base plate, or between the insulating member and the bottom of the groove / insulating sheet, which may prevent the inverter's heat dissipation and insulation performance from adequately coping with the increased voltage of the electric compressor.

[0006] SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an electric compressor in which the heat dissipation performance and insulation performance of a drive circuit that drives an electric motor are improved. [Means for solving the problem]

[0007] In order to achieve the above object, in the electric compressor of the present invention, a drive circuit for driving the electric motor is installed in a housing that accommodates a compression mechanism and an electric motor that is a power source of the compression mechanism, thereby forming an integrated drive circuit type, and an installation surface of the housing of a package that contains switching elements of the drive circuit is provided as a bottom surface of a recessed portion formed in the housing, and the package is fixed by screwing threaded portions of bolts inserted into bolt insertion holes of the package into screw holes formed in the installation surface, an insulating spacer having a through hole through which a threaded portion of a bolt is inserted is interposed between the installation target surface and a bottom surface of the package that faces the installation target surface, and a recess extending from the outer peripheral surface of the spacer toward the through hole is formed on an upper surface of the spacer that faces the bottom surface of the package and on a bottom surface of the spacer that faces the installation target surface; The recess is filled with a sealant. [Effects of the Invention]

[0008] According to the electric compressor of the present invention, it is possible to improve the heat dissipation performance and insulation performance of the drive circuit that drives the electric motor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing an example of a refrigeration cycle to which an electric compressor is applied. [Figure 2] FIG. 2 is a schematic cross-sectional view of an electric compressor. [Figure 3] FIG. 2 is a perspective view showing the package from the top side. [Figure 4]FIG. 2 is a perspective view showing the package from the bottom side. [Figure 5] FIG. 4 is a schematic cross-sectional view taken along line AA in FIG. 3. [Figure 6] FIG. 2 is a schematic cross-sectional view showing components used to install the package. [Figure 7] FIG. 10 is a perspective view showing an example of a spacer. [Figure 8] FIG. 10 is a schematic cross-sectional view showing a state in which the package is fixed with screws. [Figure 9] FIG. 2 is a schematic cross-sectional view showing a sealed state of the package. [Figure 10] FIG. 10 is a perspective view showing a specific installation mode of the package. [Figure 11] FIG. 10 is a perspective view showing a first modified example of the spacer. [Figure 12] FIG. 12 is a cross-sectional view taken along line BB in FIG. [Figure 13] FIG. 10 is a schematic cross-sectional view showing a package sealed state using a first modified example of the spacer. [Figure 14] FIG. 10 is a perspective view showing a second modified example of the spacer. [Figure 15] FIG. 15 is a cross-sectional view taken along line CC in FIG. [Figure 16] FIG. 10 is a schematic cross-sectional view showing a package sealed state using a second modified example of the spacer. [Figure 17] FIG. 10 is a schematic cross-sectional view showing a screw-fixed state of a conventional package. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of a refrigeration cycle using an electric compressor.

[0011] Refrigeration cycle 1 is a vapor pressure refrigeration cycle configured with an electric compressor 3, a condenser 4, an expansion valve 5, and an evaporator 6 arranged in this order around refrigerant piping 2 through which refrigerant circulates. Electric compressor 3 compresses low-temperature, low-pressure gaseous refrigerant to produce high-temperature, high-pressure gaseous refrigerant. Condenser 4 cools the high-temperature, high-pressure gaseous refrigerant that has passed through electric compressor 3 to produce low-temperature, high-pressure liquid refrigerant. Expansion valve 5 decompresses the low-temperature, high-pressure liquid refrigerant to produce low-temperature, low-pressure liquid refrigerant. Evaporator 6 vaporizes the low-temperature, low-pressure liquid refrigerant to produce low-temperature, low-pressure gaseous refrigerant. This type of refrigeration cycle 1 can be applied to a variety of devices, whether on-board or stationary, such as air conditioners and heat pumps.

[0012] 2 shows an example of an electric compressor 3. The electric compressor 3 is configured as an inverter-integrated type in which an inverter 40, which is a drive circuit for the electric motor 20, is installed in a housing 30 that accommodates a compression mechanism 10 and an electric motor 20 that is its power source.

[0013] The housing 30 is a hollow body having an internally sealed space formed by fastening a rear housing 31, a center housing 32, a front housing 33, and an inverter cover 34 together with fasteners such as bolts and washers, and is made of a metal such as an aluminum alloy. The internally sealed space is generally partitioned into three spaces arranged in series by a first partition wall 35 and a second partition wall 36. Specifically, the first space H1 is formed by fastening the rear housing 31 to the center housing 32 having the first partition wall 35, and the compression mechanism 10 is accommodated in the first space H1. The second space H2 is formed by fastening the center housing 32 having the first partition wall 35 to the front housing 33 having the second partition wall 36, and the electric motor 20 is accommodated in the second space H2. The third space H3 is formed by fastening the front housing 33 having the second partition wall 36 to the inverter cover 34, and the inverter 40 is accommodated in the third space H3.

[0014] The rear housing 31 is provided with a discharge port Pout for discharging the high-temperature, high-pressure gas refrigerant generated by the compression mechanism 10 from the first space H1 to the outside. The front housing 33 is provided with a suction port Pin for drawing the low-temperature, low-pressure gas refrigerant vaporized in the evaporator from the outside into the second space H2. The center housing 32 is formed with a communication passage (not shown) that connects the first space H1 and the second space H2, and the low-temperature, low-pressure gas refrigerant drawn into the second space H2 via the suction port Pin is introduced into the first space H1 via the communication passage.

[0015] The compression mechanism 10 has a movable body driven by the rotational output of the electric motor 20. The movement of the movable body compresses the low-temperature, low-pressure gas refrigerant introduced into the first space H1, generating high-temperature, high-pressure gas refrigerant. The compression mechanism 10 can employ any compression method as long as it utilizes the rotational output of the electric motor 20. For example, the compression mechanism 10 can employ a scroll method in which the rotational output of the electric motor 20 is used to generate the orbital motion of an orbiting scroll, thereby changing the volume of a compression chamber formed by the meshing of a fixed scroll and the orbiting scroll. Alternatively, the compression mechanism 10 can employ a rotary method in which the rotational output of the electric motor 20 rotates a rotor inside a casing, continuously changing the volume of a compression chamber formed between the casing and the rotor.

[0016] Although not shown, the first space H1 may be provided with a discharge chamber for temporarily storing the high-temperature, high-pressure gas refrigerant generated by the compression mechanism 10 to reduce pulsation, and a gas-liquid separation chamber for separating lubricating oil from the high-temperature, high-pressure gas refrigerant.

[0017] The electric motor 20 is, for example, a three-phase permanent magnet synchronous motor, and includes a rotor 21 having a generally cylindrical or columnar shape with permanent magnets arranged sequentially in the circumferential direction, and a stator 23 having a plurality of teeth arranged in the circumferential direction and wound with stator coils 22, the teeth facing the outer circumferential surface of the rotor 21. A motor shaft 24 extending perpendicular to the radial direction is fixed to the radial center of the rotor 21. One end of the motor shaft 24 is rotatably supported by a support portion 36A provided on a second partition wall 36 of the front housing 33 via a plain bearing (not shown). The other end of the motor shaft 24 penetrates a first partition wall 35 of the center housing 32 and is connected to a movable body of the compression mechanism 10. The motor shaft 24 is also rotatably supported by a bearing 25 arranged on the first partition wall 35 in the first space H1. As a result, the rotor 21 rotates relative to the stator 23 around the axis of the motor shaft 24. Connection terminals 26 for electrically connecting each phase coil of the stator coil 22 to the inverter 40 are provided on the stator 23 and hermetically penetrate the second partition wall 36, with insulation being provided between the connection terminals 26 and the second partition wall 36. When a rotating magnetic field is generated in the stator coil 22 by the passage of current from the inverter 40 via the connection terminals 26, a rotational force is generated in the rotor 21, and the rotational output of the electric motor 20 is transmitted to the movable body of the compression mechanism 10 via the motor shaft 24.

[0018] The inverter 40 is a power conversion device that includes a three-phase bridge circuit having six switching elements 41, converts DC current input from an external DC power supply into three-phase AC current using this three-phase bridge circuit, and supplies the three-phase AC current to the stator coil 22 of the electric motor 20. The three-phase bridge circuit is configured such that each phase arm, in which two switching elements 41 are connected in series, is connected in parallel between a positive bus and a negative bus that are connected to an external DC power supply, and the two switching elements 41 of each phase arm are connected to the connection terminal 26 of the stator coil 22 of the corresponding phase.

[0019] Six switching elements 41 of a three-phase bridge circuit of the inverter 40 are mounted on the second partition wall 36. Mounting the switching elements 41 on the second partition wall 36 promotes heat dissipation from the switching elements 41 due to the heat absorption effect of the low-temperature, low-pressure gas refrigerant drawn into the second space H2 through the suction port Pin. The inverter 40 is formed on a circuit board 50 that is fixed with bolts 37 to a boss portion 36B extending from the second partition wall 36 and extends substantially parallel to and spaced from the second partition wall 36. Conductive paths excluding the six switching elements 41 of the three-phase bridge circuit are formed as conductive patterns on the circuit board 50, and the conductive patterns are electrically connected to the connection terminals 26. A power supply line 51 connected to the positive and negative terminals of an external DC power supply and a signal line 52 through which an external operation command for the electric compressor 3 is transmitted are electrically connected to the circuit board 50 via a pluggable connector 53. The power supply line 51 is connected to the conductive patterns of the positive and negative buses of the inverter 40 , and the signal line 52 is connected to a control circuit 54 such as a microcomputer mounted on the circuit board 50 .

[0020] Next, specific aspects of the switching element 41 will be described with reference to Fig. 3 to Fig. 5. As will be described later, the switching element 41 is contained in a package, with Fig. 3 showing the package from the top side, Fig. 4 showing the package from the bottom side, and Fig. 5 showing a cross section of the package.

[0021] The switching element 41 is a power semiconductor element, such as an IGBT (Insulated Gate Bipolar Transistor), that performs switching operations based on control signals output from the control circuit 54. The switching element 41 is formed as a semiconductor chip with electrode pads for electrical connection to the outside. The switching element 41 is enclosed in a package 100 that is formed by sealing the switching element 41 with a predetermined sealing material, such as a resin mold made of epoxy resin. The package 100 is formed in a substantially flat rectangular parallelepiped shape with a bottom surface 100A that serves as a flat installation surface for installing the switching element 41 on the second partition wall 36. The package 100 includes a die pad 101 and leads 102 in addition to the switching element 41. The die pad 101 is a metal plate that supports and fixes the switching element 41 via an insulating layer and also dissipates heat generated by the switching element 41. The switching element 41 is supported and fixed on one surface 101A of the die pad 101, and a back surface 101B opposite the one surface 101A of the die pad 101 is exposed to the outside and flush with the bottom surface 100A of the package 100. The lead 102 is a metal terminal for electrically connecting the switching element 41 and the conductive pattern on the circuit board 50, and may be formed by punching out from the same lead frame as the die pad 101. One end of the lead 102 is electrically connected to an electrode pad of the switching element 41 by, for example, wire bonding, and the other end of the lead 102 extends to the outside of the package 100 and is formed into an L-shape for connection to the conductive pattern on the circuit board 50.

[0022] In order to insert a bolt for fixing the package 100 to the second partition wall 36, a bolt insertion hole 100C is drilled in advance in the package 100, which penetrates from the bottom surface 100A to the opposite top surface 100B while being spaced apart from the switching element 41, the die pad 101, and the leads 102. When the package 100 is formed by resin molding the switching element 41, the die pad 101 is pressed down by pressing pins from both the one surface 101A and the back surface 101B during resin molding, and therefore a cutout portion 100D is formed in the package 100 by cutting out the resin so that the one surface 101A side of the die pad 101 is exposed to the outside.

[0023] Next, a method for installing the package 100 on the second partition wall 36 will be described with reference to Fig. 6 and Fig. 7. Fig. 6 shows a structure for installing the package 100. Fig. 7 shows an example of a spacer, which is one of the components used for installing the package 100 on the second partition wall 36.

[0024] 6, a female screw hole 362 that screws onto the threaded portion 110A of the bolt 110 is formed in a flat installation target surface 361 of the package 100 in the second partition wall 36. The package 100 is installed in the second partition wall 36 with its bottom surface 100A facing the installation target surface 361 of the second partition wall 36, by screwing the threaded portion 110A of the bolt 110 that has been inserted into the bolt insertion hole 100C from the top surface 100B side into the female screw hole 362. The bolt 110 is selected so that the threaded portion 110A is allowed to pass through the bolt insertion hole 100C, but the head portion 110B is prevented from passing through the bolt insertion hole 100C.

[0025] A partition wall 363 stands from the second partition wall 36, surrounding the entire periphery of the installation target surface 361, and the area surrounded by this partition wall 363 forms a recessed portion 364. In other words, the installation target surface 361 forms the bottom surface of the recessed portion 364. The height of the partition wall 363 relative to the installation target surface 361 of the second partition wall 36 is higher than both the position at which the leads 102 protrude from the package 100 to the outside when the package 100 is installed on the second partition wall 36 and the position at which one surface 101A of the die pad 101 is exposed by the cutout portion 100D.

[0026] A groove 365 is formed in the installation target surface 361 of the second partition 36, with the periphery of the opening of the female screw hole 362 recessed a predetermined depth d from the installation target surface 361. A spacer 120 having good insulating properties is disposed on a bottom surface 365A of this groove 365, and an inner peripheral surface 365B of the groove 365 determines the position of the spacer 120 on the installation target surface 361. The package 100 is screwed in place with bolts 110, and is pressed against the second partition 36 via the spacer 120.

[0027] 6 and 7, the spacer 120 includes a base 121 and a cylindrical body 122. The base 121 has an outer peripheral surface 121A that fits into the groove 365, and is formed with a constant thickness of predetermined thickness t from a bottom surface 121B that abuts against a bottom surface 365A of the groove 365. The base 121 has a through hole 121C through which the threaded portion 110A of the bolt 110 is inserted at a portion that corresponds to the female threaded hole 362 when the base 121 is fitted into the groove 365. The predetermined thickness t of the base 121 is greater than the predetermined depth d of the groove 365. The cylindrical body 122 has an inner peripheral surface 122A that extends from the periphery of the through hole 121C in the insertion direction of the threaded portion 110A of the bolt 110 and that is an extension of the inner peripheral surface of the through hole 121C on the top surface 121D opposite the bottom surface 121B of the base 121, and has an outer peripheral surface 122B that can be inserted into the bolt insertion hole 100C of the package 100. When the package 100 is installed in the second partition wall 36, the cylindrical body 122 is inserted into the gap between the outer peripheral surface of the threaded portion 110A of the bolt 110 and the inner peripheral surface of the bolt insertion hole 100C. When the package 100 is screwed and fixed to the second partition wall 36 with the bolt 110, the base 121 is sandwiched between the bottom surface 365A of the groove portion 365 and the bottom surface 100A of the package 100.

[0028] 8 shows a screw-fixed state of the package 100, in which the package 100 is screw-fixed to the second partition wall 36 with bolts 110. As shown in Fig. 8, when the package 100 is screw-fixed, a gap of a distance (td) which is the difference between the predetermined thickness t and the predetermined depth d is generated between the bottom surface 100A of the package 100 and the installation target surface 361 of the second partition wall 36.

[0029] Here, with reference to Fig. 17, the reason for forming the gap of distance (td) as shown in Fig. 8 will be described. Fig. 17 shows a conventional screw-fixed state of package 100 in which the predetermined thickness t and predetermined depth d in Fig. 8 are the same value, top surface 121D of base 121 and installation surface 361 of second partition wall 36 are flush with each other, and an insulating sheet IS having good thermal conductivity is interposed between bottom surface 100A of package 100 and installation surface 361 of second partition wall 36 and top surface 121D of base 121.

[0030] 17, the pressure exerted by bolt 110 on the package when it is screwed in is limited by the allowable mechanical stress of switching element 41. Furthermore, manufacturing tolerances are typically included in the predetermined thickness t of base 121 and the predetermined depth d of groove 365. Due to at least one of these two factors, when package 100 is fixed with the screws in FIG. 17, extremely small gaps are formed between bottom surface 100A of package 100 and insulating sheet IS, between insulating sheet IS and installation surface 361 of second partition wall 36 and upper surface 121D of base 121, and between bottom surface 121B of base 121 and bottom surface 365A of groove 365, as indicated by the thick dashed lines in the figure. Furthermore, due to manufacturing tolerances of the bolt insertion hole 100C, the spacer 120, the groove 365, and the insulating sheet IS, as shown by the thick solid lines in the figure, very small gaps are generated between the inner circumferential surface of the bolt insertion hole 100C and the outer circumferential surface 122B of the cylindrical body 122, between the inner circumferential surface 365B of the groove 365 and the outer circumferential surface 121A of the base 121, and between the insulating sheet IS and the outer circumferential surface 122B of the cylindrical body 122. All of these very small gaps can be part of the discharge path from the back surface 101B of the die pad 101 to the installation surface 361 of the bolt 110 or the second partition wall 36, but all of the discharge paths follow a more complex path than the shortest distance from the back surface 101B of the die pad 101 to the installation surface 361 of the bolt 110 or the second partition wall 36, resulting in a longer insulation distance. In particular, the insulation distance of the discharge path from the back surface 101B of the die pad 101 to the nearest bolt 110 is increased by the presence of the spacer 120. Therefore, if the electric compressor 3 is driven at a relatively low voltage, the above-mentioned extremely small gap has little effect on the insulation performance and heat dissipation performance of the inverter 40. However, if the electric compressor 3 is driven at a relatively high voltage, for example, 800 V or higher, even the above-mentioned extremely small gap may cause insulation breakdown or make sufficient heat dissipation difficult, resulting in insufficient insulation performance and heat dissipation performance of the inverter 40. Therefore, in order to minimize the above-mentioned extremely small gap, a gap of a distance (td) is intentionally formed as shown in FIG. 8 so that a fluid (e.g., liquid) sealing material is filled between the installation target surface 361 of the second partition wall 36 and the bottom surface 100A of the package 100 instead of the insulating sheet IS.

[0031] 9 shows a sealed state of the package 100 with a fluid sealant. The fluid sealant 200 is a material with good insulating properties and thermal conductivity, such as a resin composition (silicon resin, urethane resin, or epoxy resin), and is filled into the recessed portion 364 by potting or the like while the package 100 is screwed and fixed as shown in FIG. 8. The fluid sealant 200 may be filled by evacuating the entire front housing 33 where the package 100 is screwed and fixed to the second partition wall 36, or the recessed portion 364. The fluid sealant 200 spreads onto the installation surface 361 in the recessed portion 364, raising the surface height and first filling the gap (td).

[0032] 8, when package 100 is fixed with the screws, as shown by the thick dashed lines in the figure, very small gaps are generated between bottom surface 100A of package 100 and top surface 121D of base 121 and between bottom surface 121B of base 121 and bottom surface 365A of groove 365 due to at least one of two factors: a limit on the package pressing force when bolt 110 is screwed in and manufacturing tolerances of predetermined thickness t of base 121 and predetermined depth d of groove 365. In addition, as shown by the thick solid lines in the figure, very small gaps are generated between the inner circumferential surface of bolt insertion hole 100C and outer circumferential surface 122B of cylindrical body 122 and between inner circumferential surface 365B of groove 365 and outer circumferential surface 121A of base 121 due to manufacturing tolerances of bolt insertion hole 100C, spacer 120, and groove 365. By appropriately selecting the fluid sealing material 200 in view of viscosity and the like, the fluid sealing material 200 filled in the gap of the interval (td) is sucked in by capillary action into these very small gaps. As a result, the very small gaps are filled with the sealing material 200 until the insulation distance from the back surface 101B of the die pad 101 reaches a level that is sufficient to handle the increased voltage of the electric compressor 3.

[0033] When the electric compressor 3 is driven at a relatively high voltage, for example, 800 V or higher, a possible discharge destination from the back surface 101B of the die pad 101 is the origin of the leads 102 protruding from the package 100 to the outside. Although not shown in FIG. 9 , the above-mentioned discharge destination may also be the front surface side of the die pad 101 exposed by the cutout 100D. Therefore, the fluid encapsulant 200 is filled into the recess 364 so as to seal the above-mentioned possible discharge destination. Even when filled in this manner, as described above, the partition wall 363 extends upright to a position higher than both the origin of the leads 102 protruding from the package 100 to the outside and the position where the one surface 101A of the die pad 101 is exposed by the cutout 100D, thereby preventing the encapsulant from leaking and spreading to the surrounding area.

[0034] The fluid sealing material 200 filled in the recessed portion 364 is hardened by natural drying, heating, ultraviolet irradiation, or the like. The height of the partition wall 363 relative to the installation surface 361 of the second partition wall 36 may be made higher than the head 110B of the bolt 110 when the package 100 is in a screw-fixed state. In this way, the sealing material 200 can be filled without leaking and spreading to the surrounding area until the surface height of the fluid sealing material 200 is higher than the head 110B of the bolt 110, thereby reducing the possibility of discharge to or from the head 110B of the bolt 110.

[0035] 10 shows a specific installation state of the packages 100 in the second partition 36 with the inverter cover 34 and circuit board 50 removed from the front housing 33. The six packages 100, each containing a switching element 41, are spaced apart from one another and arranged in parallel in two rows of three packages 100 each, with the packages 100 in each row facing the leads 102 of the packages 100 in the adjacent row, and are fixed to the second partition 36 with bolts 110. The six packages 100 are surrounded by a single annular partition 363 spaced apart from the six packages 100, and a recess 364 formed by this partition 363 is filled with and cured by the sealing material 200. If the layout of the circuit board 50 and the second partition wall 36 makes it difficult to surround the six packages 100 with one annular partition wall 363, multiple partition walls 363 may be provided in different locations, and one or more packages 100 may be placed in a recess 364 formed by each partition wall 363. Furthermore, instead of containing the switching elements 41 individually in the six packages 100, the switching elements 41 may be contained in a single modularized package 100 and placed in a recess 364 formed by one partition wall 363 of the second partition wall 36. Note that the peripheral wall of the front housing 33 surrounding the circuit board 50 can be used as part of the partition wall 363.

[0036] In the electric compressor 3 configured as described above, the base 121 of the spacer 120 forms a gap (td) between the bottom surface 100A of the package 100 and the installation surface 361 of the second partition wall 36, and this gap is filled with a fluid sealant 200 having good electrical insulation and thermal conductivity. A very small gap, which is caused by at least one of two factors: limitations on the package pressing force when the bolt 110 is screwed in, and manufacturing tolerances of the bolt insertion hole 100C, the spacer 120, and the groove 365, is filled by the fluid sealant 200 entering the gap (td) by capillary action. The sealant 200 is also filled until the protrusion bases of the leads 102 protruding to the outside of the package 100 and the one surface 101A of the die pad 101 exposed by the cutout 100D are also sealed. Therefore, the insulation distance from the back surface 101B of the die pad 101 to the discharge destination such as the bolt 110 and the thermal resistance from the back surface 101B of the die pad 101 to the second partition wall 36 can be set to a level that is sufficient to accommodate the increased voltage of the electric compressor 3.

[0037] Furthermore, in the electric compressor 3, the package 100 is installed on the bottom surface of the recess 364 formed by surrounding it in a ring shape with the partition wall 363 erected from the second partition wall 36, which serves as the installation surface 361. Therefore, even if the fluid sealing material 200 is filled into the recess 364, it does not leak and spread around the partition wall 363, and the amount of sealing material 200 used can be reduced.

[0038] Next, a first modified example of the spacer 120 will be described with reference to Figs. 11 to 13. Fig. 11 shows a spacer according to the first modified example. Fig. 12 shows a cross section of the base of the spacer according to the first modified example. Fig. 13 shows the sealed state of the package 100 when the spacer according to the first modified example is used. Note that the same reference numerals are used to designate the same components as in the above embodiment, and their description will be omitted or simplified. The same applies to the following modified examples.

[0039] As shown in Fig. 11, a spacer 120i according to this modification is obtained by modifying the configuration of the base 121 with respect to the spacer 120 described above. Specifically, in the spacer 120i, one or more recesses 121E are formed by recessing an upper surface 121D of the base 121 in the thickness direction, and one or more recesses 121F are formed by recessing a bottom surface 121B of the base 121 in the thickness direction from the outer peripheral surface 121A toward the center. As shown in Fig. 12, when viewed from the upper surface 121D of the base 121, the recesses 121E and 121F extend from the outer peripheral surface 121A of the base 121 to the outer peripheral surface 122B of the cylindrical body 122, and are blocked by a peripheral wall 121G around the through-hole 121C.

[0040] 13, the fluid encapsulant 200 filled in the gap of the interval (td) enters the recesses 121E and 121F provided in the top surface 121D and bottom surface 121B of the base 121. In the recess 121E provided in the top surface 121D of the base 121, the fluid encapsulant 200 flows along the bottom surface 100A of the package 100 to the peripheral wall 121G. In the recess 121F provided in the bottom surface 121B of the base 121, the fluid encapsulant 200 flows along the bottom surface 365A of the groove 365 to the peripheral wall 121G. The fluid sealing material 200 that has flowed into the recesses 121E and 121F in this manner is further sucked by capillary action into the very small gap between the upper surface 121D of the base 121 and the bottom surface 100A of the package 100 and the very small gap between the bottom surface 121B of the base 121 and the bottom surface 365A of the groove 365. Therefore, by providing the recesses 121E and 121F in the base 121, the fluid sealing material 200 is promoted to be sucked into the very small gaps by capillary action not only from the outer peripheral surface 121A of the base 121 but also from the recesses 121E and 121F, and the filling efficiency of the sealing material 200 can be improved. Furthermore, the fluid sealing material 200 filled in the gap of the interval (td) easily reaches the entrance of the gap between the inner peripheral surface of the bolt insertion hole 100C and the outer peripheral surface 122B of the cylindrical body 122 via the recess 121E provided on the upper surface 121D of the base 121, promoting suction into this gap by capillary action, which also improves the filling efficiency of the sealing material 200.

[0041] Instead of recesses 121E and 121F, recess 121E on top surface 121D and recess 121F on bottom surface 121B may be connected in the thickness direction of base 121 to form a slit extending from outer circumferential surface 121A of base 121 toward through-hole 121C.

[0042] Next, a second modified example of the spacer 120 will be described with reference to Figs. 14 to 16. Fig. 14 shows a spacer according to the second modified example. Fig. 15 shows a cross section of the base of the spacer according to the second modified example. Fig. 16 shows the sealed state of the package 100 when the spacer according to the second modified example is used.

[0043] As shown in Fig. 14, a spacer 120ii according to this modification is a spacer 120i according to the first modification, with the cylindrical body 122 omitted. Specifically, the spacer 120ii is the base 121 itself, and includes one or more recesses 121E formed by recessing an upper surface 121D of the base 121 in the thickness direction and one or more recesses 121F formed by recessing a bottom surface 121B of the base 121 in the thickness direction, extending from the outer peripheral surface 121A toward the center. However, as shown in Fig. 15, unlike the spacer 120i described above, the recesses 121E and 121F extend from the outer peripheral surface 121A of the base 121 to the through-holes 121C when viewed from the upper surface 121D of the base 121.

[0044] 16, the fluid encapsulant 200 filled in the gap of the interval (td) enters the recesses 121E and 121F provided in the top surface 121D and bottom surface 121B of the base 121, respectively. In the recess 121E provided in the top surface 121D of the base 121, the fluid encapsulant 200 flows along the bottom surface 100A of the package 100 to the through-hole 121C. In the recess 121F provided in the bottom surface 121B of the base 121, the fluid encapsulant 200 flows along the bottom surface 365A of the groove 365 to the through-hole 121C. By providing the recesses 121E and 121F in the base 121, the fluid encapsulant 200 is sucked into the extremely small gaps by capillary action not only from the outer peripheral surface 121A of the base 121 but also from the recesses, similar to the above-described spacer 120i. In addition, in the spacer 120ii, the fluid sealing material 200 that has reached the through hole 121C can easily enter the gap between the inner peripheral surface of the bolt insertion hole 100C and the outer peripheral surface of the threaded portion 110A, and between the inner peripheral surface of the female threaded hole 362 and the outer peripheral surface of the threaded portion 110A, making it possible to seal almost the entire outer peripheral surface of the threaded portion 110A with the sealing material 200. Therefore, the insulation distance from the back surface 101B of the die pad 101 to the bolt 110 can be further increased, and the insulation performance of the inverter 40 can be improved.

[0045] The present invention has been specifically described above with reference to preferred embodiments and modifications thereof. However, it is obvious that a person skilled in the art can adopt various modifications as described below based on the basic technical concept and teachings of the present invention.

[0046] In the above embodiment, the recess 364 was formed by surrounding the entire installation surface 361 with the partition wall 363 erected from the second partition wall 36, but instead, the recess 364 may be formed by recessing the second partition wall 36.

[0047] The package 100 may be fixed to the installation target surface 361 of the second partition 36 by screws without using the spacers 120, 120i, and 120ii. Even in this case, the fluid encapsulant 200 filled in the recess 364 can enter the extremely small gap between the installation target surface 361 of the second partition 36 and the bottom surface 100A of the package 100 by capillary action.

[0048] In the above embodiment, the spacers 120, 120i, and 120ii are arranged in grooves 365 formed in the installation surface 361 of the second partition 36, but if the package 100 can be screwed without positioning the spacers 120, 120i, and 120ii, the grooves 365 may be omitted.

[0049] The electric motor 20 may be an AC motor or a DC brushed motor other than a permanent magnet synchronous motor, as long as it is driven by a drive circuit having one or more power semiconductor elements. Therefore, the drive circuit that drives the electric motor 20 is not limited to the inverter 40.

[0050] In the above package 100, the back surface 101B of the die pad 101 that supports and fixes the switching element 41 is flush with the bottom surface 100A of the package 100 and exposed to the outside, but this is not limited to this. A metal plate for heat dissipation may be bonded to the back surface 101B of the die pad 101, and the surface opposite the bonding surface of this metal plate may be flush with the bottom surface 100A of the package 100 and exposed to the outside.

[0051] Although the package 100 containing the switching element 41 is described as being installed on the installation target surface 361 of the second partition wall 36, this is not limiting, and the package 100 may be installed on the installation target surface 361, which is formed on the outer peripheral surface of the peripheral wall of the front housing 33. In this case, the circuit board 50 is fixed with screws to bosses extending from the outer peripheral surface of the front housing 33 or the center housing 32, and the third space H3 is formed on the outer peripheral surface of the front housing 33 or the center housing 32. The package 100 containing the switching element 41 may also be installed on a base plate separate from the front housing 33, instead of the second partition wall 36. As long as the back surface of the base plate opposite the installation target surface 361 of the package 100 is flat, it is preferable that the back surface be joined to the front housing 33 from the viewpoint of heat dissipation of the switching element 41.

[0052] The base 121 of the spacer 120i according to the first modification does not need to have the peripheral wall 121G. This allows the fluid sealant 200 introduced into the recess to also enter the through hole 121C, so that the outer peripheral surface of the threaded portion 110A of the bolt 110 can be covered.

[0053] The technical ideas and modifications based on them described in the above embodiments and modifications can be used in any suitable combination as long as no contradictions arise. For example, even when the package 100 is screw-fixed using the spacers 120i and 120ii according to the first and second modifications, the sealing material 200 may be filled until the surface height of the fluid sealing material 200 is higher than the head 110B of the bolt 110. [Explanation of symbols]

[0054] 3...electric compressor, 10...compression mechanism, 20...electric motor, 30...housing, 33...front housing, 36...second partition (partition), 40...inverter (drive circuit), 41...switching element, 50...circuit board, 100...package, 100A...bottom surface, 100C...bolt insertion hole, 100D...notch, 101...die pad, 101A...one surface, 102...rib 121C...through hole; 121D...upper surface; 121E, 121F...recess; 122...tubular body; 200...sealing material; 361...mounting surface; 362...female thread hole; 364...recess; H2...second space (refrigerant introduction space); H3...third space (circuit accommodating space)

Claims

1. An electric compressor having an integrated drive circuit in which a drive circuit for driving the electric motor is installed in a housing that accommodates a compression mechanism and an electric motor that is a power source of the compression mechanism, an installation surface of the housing of a package containing the switching element of the drive circuit is provided as a bottom surface of a recess formed in the housing, and the package is fixed by threading a threaded portion of a bolt inserted into a bolt insertion hole of the package into a screw hole formed in the installation surface; an insulating spacer having a through hole through which the threaded portion of the bolt is inserted is interposed between a bottom surface of the package facing the installation surface and the installation surface; a recess extending from an outer peripheral surface of the spacer toward the through hole is formed on an upper surface of the spacer that faces the bottom surface of the package and a bottom surface of the spacer that faces the installation target surface, The recess is filled with a sealant. Electric compressor.

2. An electric compressor as described in claim 1, wherein the spacer further includes a cylindrical body extending from the spacer along the threaded portion of the bolt to the inside of the insertion hole.

3. An electric compressor as described in claim 1 or claim 2, wherein the package has a die pad that supports and fixes the switching element and leads that connect the switching element to a circuit board outside the package, and the sealing material is filled into the recessed portion up to a position higher than the position at which the lead protrudes outside the package and the position at which the package is cut out and the die pad is exposed outside the package, based on the installation surface.

4. An electric compressor as described in any one of claims 1 to 3, wherein the drive circuit is accommodated in a drive circuit accommodating space adjacent to a refrigerant introduction space in the housing into which a refrigerant is introduced, and the installation surface is formed as a partition wall separating the refrigerant introduction space and the circuit accommodating space.

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