EP4252338A1

EP4252338A1 - An electric machine

Info

Publication number: EP4252338A1
Application number: EP21897946.6A
Authority: EP
Inventors: Herve Ribot; Hariharan BANUMURTHY; Mathieu VARILLON; Prakash GANESAN; Baskaran RAJA
Original assignee: Valeo Japan Co Ltd
Current assignee: Valeo Japan Co Ltd
Priority date: 2020-11-27
Filing date: 2021-11-24
Publication date: 2023-10-04
Also published as: CN116569454A; JP2023553306A; WO2022113974A1

Abstract

An electric machine for a vehicle air-conditioner is provided. The electric machine includes a first housing, a second housing, a sealing element, and a plurality of tension-loaded members. The first housing having a first mating surface is adapted to accommodate an electric motor and the second housing having a second mating surface is adapted to accommodate an inverter assembly. Further, the first mating surface and second mating surface are complimentary and opposite to each other. The sealing element is disposed between the first mating surface and second mating surface, and the second housing is adapted to be coupled with the first housing. Further, the plurality of tension-loaded members is provided in holes formed on the first mating surface and the second mating surface, while coupling the first housing with the second housing.

Description

AN ELECTRIC MACHINE

The present invention generally relates to an electric machine, more particularly to, a connection between a motor housing and an inverter housing of an electric machine to reduce leakage of electromagnetic noise from the housing of the electric machine.

Generally, an electric machine, particularly electric compressor, is provided in AC loop of a vehicle. The electric compressor includes a compression unit for compressing refrigerant, an electric motor that drives the compression unit, and an inverter assembly that drives the electric motor in a controlled manner. Further, housings are provided to encapsulate respective parts of the electric compressor and are mechanically coupled together with various fasteners. In one example, a motor housing is provided to encapsulate the electric motor, and an inventor housing is provided to encapsulate the inverter assembly. The electric motor provided in the compressor enables the compression unit to draw the refrigerant from an inlet port formed on the motor housing to cool the electric motor by circulating the refrigerant through the motor housing. Generally, the motor housing is formed with the aluminium material in a cylindrical shape having openings on either sides. Further, the refrigerant enters into the compression unit for compression, and flows out from the electric compressor through a discharge port formed on a rear cover that is coupled to one end of the motor housing. From other end of the motor housing, the electric motor is inserted and is coupled with an inverter housing. Conventionally, mating portions of each of the housings are sealed with gaskets to prevent leakage of the refrigerant. Generally, a gasket disposed between the motor housing and the inverter housing is having three layers such as a base plate made of metallic material as a first layer, and rubber coated on both sides of the base plate forms second and third layers. The inverter housing further includes a High Voltage (HV) connector terminal and a Low Voltage (LV) connector terminal. Conventionally, electromagnetic noise is generated from active parts of the electric motor in the motor housing. As the gasket is rubber coated metallic gasket, there is a possibility of transmission of the electromagnetic noise from the motor housing to the inverter housing. Further, the transmitted electromagnetic noise from the motor housing may interact with the HV and LV connector terminals. Such interactions of the electromagnetic noise on the connector terminals may enter into the inverter housing and lead to malfunctioning of control circuits encapsulated in the inverter housing.

Accordingly, there remains a need for an electric machine provided with features that avoid leakage of electromagnetic noise from a housing of the electric machine. Further, there remains another need for a connection formed between a motor housing and an inverter housing of an electric machine to reduce leakage path of electromagnetic noise by grounding such noise. Further, there remains another need for an electric machine provided with features that protect an inverter circuit from interference of the electromagnetic noise.

In the present description, some elements or parameters may be indexed, such as a first element and a second element. In this case, unless stated otherwise, this indexation is only meant to differentiate and name elements which are similar but not identical. No idea of priority should be inferred from such indexation, as these terms may be switched without betraying the invention. Additionally, this indexation does not imply any order in mounting or use of the elements of the invention.

In view of the foregoing, an embodiment of the invention herein provides an electric machine, particularly an electric compressor for a vehicle’s air-conditioner. The electric machine includes a first housing, a second housing, a sealing element, and a plurality of tension-loaded members. The first housing having a first mating surface is adapted to accommodate an electric motor and the second housing having a second mating surface is adapted to accommodate an inverter assembly. Further, the first mating surface and second mating surface are complimentary and opposite to each other. The sealing element is disposed between the first mating surface and second mating surface, and the second housing is adapted to be coupled with the first housing. Further, the plurality of tension-loaded members is provided in holes formed on the first mating surface and the second mating surface, while coupling the first housing with the second housing.

Further, the sealing element having apertures is in-line with the holes formed on the first mating surface and the second mating surface to receive the tension-loaded members there-though.

In one example, the second housing includes an extending portion extended outward in a radial direction with respect to the second housing and at least one of first and second connectors provided on a sidewall of the extending portion of the second housing.

In one example, the plurality of tension-loaded members is disposed at a circumferential area of the second mating surface, corresponding to the at least one of the first and second connectors.

The electric machine further includes a plurality of bosses formed on a side of the periphery, corresponding to the at least one of the first and second connectors, of the first mating surface and the second mating surface, wherein the holes are formed on the bosses.

In one embodiment, the holes are formed on the first mating surface and the second mating surface at a predetermined distance.

In one example, at least one of distances between the adjacent holes formed on the first mating surface and the second mating surface is less than 30 mm.

Further, the sealing element is a rubber coated metallic gasket.

Further, the plurality of tension-loaded members are spring pins.

In another example, the electric machine further comprising at least two pins formed on the second housing to position the first housing in-line with the second housing.

Other characteristics, details and advantages of the invention can be inferred from the description of the invention hereunder. A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying figures, wherein:

[Fig. 1] illustrates a block diagram of an electric machine, in accordance with an embodiment of the present invention;

[Fig. 2] illustrates a schematic view of a first housing of the electric machine of Fig. 1;

[Fig. 3] illustrates a cross-sectional view of the electric machine cut along the longitudinal axis of the electric machine of Fig. 1;

[Fig. 4] illustrates a schematic view of a second housing in a plane perpendicular to the longitudinal axis of the second housing of the electric machine of Fig. 1;

[Fig. 5] illustrates an exploded view of the second housing with an inverter assembly of the electric machine of Fig. 1;
[Fig. 6] illustrates an exploded view of the electric machine of Fig. 1; and

[Fig. 7] illustrates an enlarged sectional view of a tension-loaded member amongst a plurality of tension-loaded members coupled between the first housing and the second housing of Fig. 1.

It must be noted that the figures disclose the invention in a detailed enough way to be implemented, the figures helping to better define the invention if needs be. The invention should however not be limited to the embodiments disclosed in the description.

The present invention relates to an electric machine, particularly to an electric compressor, provided in an air-conditioning loop of a vehicle. Generally, the electric compressor includes a motor housing provided with an electric motor and an inverter housing provided with an inverter assembly. The motor housing and the inverter housing are coupled together to enable connection between the electric motor and the inverter. Further, the electric motor is connected with a compression unit to compress a refrigerant flowing therein. To enable fluid tight connection between the motor housing and the inverter housing, a rubber coated metallic gasket is provided in between the motor housing and the inverter housing. Such a rubber coated on the gasket allows to transmit the electromagnetic noise generated by the electric motor provided in the motor housing. Hence, such gasket may transmit the electromagnetic noise to the inverter assembly, and results in malfunctioning of the inverter assembly. To avoid such a scenario, a physical connection between the inverter housing and the motor housing is enabled. Such physical connection interacts with outer body of the electric machine, which is connected to the vehicle’s ground. Therefore, the electromagnetic noise is restricted from entering into the inverter housing. Further, placement and function of the physical connection are explained with respect to the following figures.

Fig. 1 illustrates a block diagram of an electric machine 100, in accordance with an embodiment of the present invention. In present embodiment, the electric machine 100 is an electric compressor, particularly, an inverter integrated motor driven electric compressor 100. The electric machine 100 is provided in a refrigerant circuit of a vehicle. Generally, the electric machine 100 is provided in the refrigerant circuit of the vehicle to compress the refrigerant flowing therein. The electric machine 100 includes a first housing 110 adapted to accommodate an electric motor 112, a second housing 120 adapted to accommodate an inverter assembly 122, and a third housing 130 adapted to accommodate a compression unit 132. Further, the first housing 110, the second housing 120 and the third housing 130 are integrally fastened with fastening means (not shown), such as bolts, so as to form a casing of the electric machine 100. In one embodiment, the first housing 110, the second housing 120 and the third housing 130 are formed of metal, particularly of aluminium die-casting.

The electric motor 112 provided in the first housing 110 includes a stator and a rotor (not shown in Fig. 1). Further, a rotary shaft 134 is connected to the rotor, and the rotary shaft 134 is extending into the third housing 130 to couple with the compression unit 132. The first housing 110 being motor housing is formed of a cylindrical shape having openings on both sides to accommodate the electric motor 112. Further, one end of the first housing 110 is coupled to the third housing 130 having the compression unit 132. From other end of the first housing 110, the electric motor 112 is inserted and is coupled with the second housing 120 having the inverter assembly 122. When the electric motor 112 is energized, the rotary shaft 134 drives the compression unit 132 provided in the third housing 130.

The compression unit 132 provided in the third housing 130 includes a fixed scroll and an orbiting scroll for compressing the refrigerant flowing therein. In one embodiment, the fixed scroll is fixedly and integrally formed with the third housing 130. The orbiting scroll is rotatably connected with an eccentric pin formed of the rotary shaft 134 extending from the first housing 110. The orbiting scroll is adapted to compress the refrigerant at a compression space defined between the fixed scroll and the orbiting scroll when the rotary shaft 134 is rotated by the electric motor 112. In other words, the refrigerant in the compression space is compressed by orbiting motion of the orbiting scroll with respect to the fixed scroll. Further, a suction port 136 is formed integrally with the first housing 110 for sucking the refrigerant into the electric machine 100. The suctioned refrigerant from the suction port 136 at the first housing 110 may flow through the electric motor 112 to cool or absorb heat generated by the electric motor 112 and enter into the third housing 130 for compression process. Thereafter, the compressed refrigerant egresses from the electric machine 100 through a discharge port 150 formed integrally with the third housing 130.

The inverter assembly 122 accommodated in the second housing120, being an inverter housing, is adapted to drive the electric motor 112 in a controlled manner. The inverter assembly 122 includes a plurality of electronic components mounted on a circuit board to perform required operations. The circuit board is powered from an external source, such as a battery of the vehicle. The circuit board is shown in Fig. 5. Further, a hermetic terminal 142 is provided on an end wall of the second housing 120 and is adapted to couple with the electric motor 112. The inverter assembly 122 generates controlled inputs for the electric motor 112 and transmits such inputs to the electric motor 112 through the hermetic terminal 142. Further, the inputs generated by the inverter assembly 122 may control the speed of the electric motor 112.

Fig. 2 illustrates a schematic view of the first housing 110 of the electric machine 100 of Fig. 1. The electric motor 112 is not shown in Fig. 2. In one embodiment, the first housing 110 includes an annular wall 208 extending to a distance to form the first housing 110 as a cylindrical shape. Further, the first housing 110 includes a first mating surface 202 defined on a longitudinal end of the first housing 110 on a direction A. In one example, the first housing 110 being in a hollow cylindrical shape and an inner circumferential surface of the first housing 110 defines an opening on the direction A. Further, the first housing 110 is having the opening on both sides to couple with the second housing 120 and the third housing 130 respectively. In one example, the opening formed on the direction A of the first housing 110 is adapted to be in-line with the second housing 120 and the opening formed on a direction B of the first housing 110 is in-line with the third housing 130. Further, the third housing 130 is mechanically coupled to the first housing 110 at the opening defined in the direction B by any connecting means. The connecting means can be a plurality of threads and bolts. In one embodiment, the electric motor 112 is inserted in the first housing 110 through the opening defined at the direction A of the first housing 110.

Further, the suction port 136 is protruding out from the annular wall 208 of the first housing 110 as shown in Fig.2. In one embodiment, the first housing 110 further may include mounting arrangement on its outer surface to allow mounting of the electric machine 100 with a vehicle body.

In addition, at least two positioning holes 210A, 210B are provided on outer and/or inner periphery of the first mating surface 202 at a predetermined distance to receive any connecting means, such as positioning pins, thereby enabling efficient positioning between the first housing 110 and the second housing 120. Particularly, the positioning holes 210A, 210B are provided at opposite side, on the periphery of the first mating surface 202, with respect to the center axis of the first housing 110.

The first housing 110 further includes a plurality of holes 204A-D formed on the first mating surface 202 at a predetermined distance. In one embodiment, the plurality of holes 204A-D is formed on the periphery of the first mating surface 202. According to the previous embodiment, a plurality of bosses 206A-D is provided on an outer peripheral surface of the opening, as shown in the Fig. 2. In other words, the plurality of bosses 206A-D is formed on an outer surface of the first housing 110 at periphery of the opening defined in the first housing 110. Further, the plurality of holes 204A-D is formed on the plurality of bosses 206A-D.

Fig. 3 illustrates a sectional view of the electric machine 100 in a plane perpendicular to the longitudinal axis of the electric machine 100 of Fig.1. The second housing 120 is having a base plate 302 and a peripheral wall 306 extending from an outer edge of the base plate 302 to define a space to accommodate the inverter assembly 122. In one embodiment, the shape of the base plate 302 is convexo-concave to correspond to the electronic components 320 of the inverter assembly 122.

Further, as shown in Fig. 3, the second housing 120 includes an extending portion 316 extended outward in a radial direction beyond the outer diameter of the first housing 110. In one embodiment, the base plate 302 of the second housing 120 includes a bottom portion 308A being complementary to the opening provided in the first housing 110 and an upper portion 308B forming a sidewall 304 of the extending portion 316. Further, the bottom portion 308A of the second housing 120 is annular in shape and adapted to couple with the first housing 110.

In one embodiment, the hermetic terminal 142 is provided on the bottom portion 308A of the base plate 302 of the second housing 120 as shown in Fig. 1 and Fig. 4. The inverter assembly 122 and the electric motor 112 are electrically connected via the hermetic terminal 142. The bottom portion 308A of the second housing 120 includes a second mating surface 310 complementary and opposite to the first mating surface 202 of the first housing 110.

Further, the second mating surface 310 includes a plurality of holes 312A-D provided on the second mating surface 310. In one embodiment, the plurality of holes 312A-D formed on the second mating surface 310 is complementary to the plurality of holes 204A-D formed on the first mating surface 202. Further, the plurality of bosses 314A-D is provided on the second mating surface 310. In one embodiment, the plurality of bosses 314A-D is provided on a periphery of the second mating surface 310.

As shown in Fig. 3 and Fig. 4, the second housing 120 is further provided with at least two connectors 318A-B on the sidewall 304 of the extending portion 316. The two connectors 318A-B include at least a first connector 318A and a second connector 318B for providing electrical energy and signal to the inverter assembly 122. In one embodiment, the first connector 318A is a high voltage terminal and the second connector 318B is a low voltage terminal.

As shown in Fig. 3 and Fig. 5, the inverter assembly 122 further includes the plurality of electronic components 320 mounted on the circuit board 138 for control operations. As shown in Fig. 5, the circuit board 138 is located in the inverter assembly accommodation space and is fixed to the base plate 302 with a plurality of bolts/screws 228. The first connector 318A and the second connector 318B are electrically connected to the electronic components 320 provided on the circuit board 138 of the inverter assembly 122 via bus bars and/or wires. In one example, the high voltage terminal 318A provides high voltage to an inverter designed by the electronic components 320. Such inverter converts the high voltage DC power to three-phase AC power and transfers such power to the electric motor 112 provided in the first housing 110. Further, the low voltage terminal 318B provides a low voltage DC power to a control unit designed by the electronic components 320 to control the electric motor 112, such as a rotation speed, number of revolutions of the rotor, turn-on and turn-off of the electric motor 112, etc.

In a preferred embodiment, the plurality of bosses 206A-D, 314A-D is formed on a side of the periphery of the first mating surface 202 of the first housing 110 and the second mating surface 310 of the second housing 120, corresponding to the connectors 318A-B. In one example, the bosses 206A-D formed on the first mating surface 202 is complementary to the bosses 314A-D formed on the second mating surface 310.

Fig. 6 illustrates an exploded view of the electric machine 100 of Fig. 1, in which a connection between the first housing 110 and the second housing 120 is depicted. As explained above, the first mating surface 202 of the first housing 110 is complementary to and adapted to couple with the second mating surface 310 of the second housing 120. Further, a sealing element 402 is provided between the first mating surface 202 and the second mating surface 310 to configure a fluid tight connection between the first housing 110 and the second housing 120. In one embodiment, the sealing element 402 is a gasket configured with three layers such as a first layer made of a metallic material, and rubber coated on both sides of the first layer forming a second and third layers. The sealing element 402 is in-contact with the first mating surface 202 and the second mating surface 310, when the first housing 110 is coupled with the second housing 120.

The sealing element 402 further includes apertures 404A-D formed on a periphery of the sealing element 402. In one embodiment, the apertures 404A-D are in-line with the holes 204A-D, 312A-D formed on the first mating surface 202 of the first housing 110 and the second mating surface 310 of the second housing 120.

The electric machine 100 further includes a plurality of tension-loaded members 406A-D provided in the holes 204A-D, 312A-D formed on the first mating surface 202 and the second mating surface 310 while coupling the first housing 110 with the second housing 120. In one example, the plurality of tension-loaded members 406A-D is spring pins. Further, the plurality of tension-loaded members 406A-D is made of a metallic material.

In one embodiment, the plurality of tension-loaded members 406A-D is disposed at a circumferential area of the second mating surface 310, corresponding to the at least one of the first connector 318A and the second connector 318B. As shown in Fig. 4 and Fig. 6, the holes 312 A-D and the tension-loaded members 406A-D inserted into the holes 312 A-D are disposed at the area between the connectors 318A-B and the inside of the second mating surface 310 where the electromagnetic noise is generated.

In another embodiment, the plurality of tension-loaded members 406A-D is adapted to elastically deform along their radial direction, when the plurality of tension-loaded members 406A-D is inserted into the holes 204A-D, 312A-D formed on the first mating surface 202 and the second mating surface 310. In one example, an outer diameter of the plurality of tension-loaded members 406A-D are equal to or larger than an inner diameter of the holes 204A-D, 312A-D. As the diameter of the holes 204A-D, 312A-D is same as the diameter of the plurality of tension-loaded members 406A-D, the plurality of tension-loaded members 406A-D needs to be elastically deformed in the radial direction, along the plurality of tension-loaded members 406A-D, so the plurality of tension-loaded members 406A-D can be easily inserted into the holes 204A-D, 312A-D. In the present example, one end of the plurality of tension-loaded members 406A-D is inserted into the holes 312A-D formed on the second mating surface 310. Thereafter, the sealing member 402 is disposed on the second mating surface 310 of the second housing 120, in such way that the plurality of tension-loaded members 406A-D provided in the holes 312A-D of the second mating surface 310 passes through the apertures 404A-D formed on the sealing member 402. Further, other end of the plurality of tension-loaded members 406A-D is inserted into the holes 204A-D formed on the first mating surface 202, when the first housing 110 is coupled to the second housing 120, thereby forming a housing for the electric machine 100. As the plurality of tension-loaded members 406A-D is provided between the first housing 110 and the second housing 120, the plurality of tension-loaded members 406A-D enables physical contact between the first housing 110 and the second housing 120. Further, the body of the second housing 120 is connected to the vehicle’s ground. As the plurality of tension-loaded members 406A-D enabling physical contact between the first housing 110 and the second housing 120, the electromagnetic noise generated by the electric motor 112 of the first housing 110 is grounded through the second housing 120.

The plurality of tension-loaded members 406A-D provided between the first housing 110 and the second housing 120, at an area corresponding to the connectors 318A-B, may prevent transmission of the electromagnetic noise to the connectors 318A-B, thereby, preventing interaction of the electromagnetic noise with the electronic components 320 provided in the inverter assembly 122.

Fig. 7 illustrates an enlarged sectional view of a tension-loaded member amongst the plurality of tension-loaded members 406A-D fixed between the first housing 110 and the second housing 120. Further, the plurality of tension-loaded members 406A-D is made of metallic material that has high electrical conductivity and EMC/EMI shielding property, such as copper, Iron, steel aluminium, etc. In one embodiment, each of the tension-loaded members 406A-D includes a pin body extended in a cylindrical shape with a slit formed in the longitudinal direction of the pin body. Further, both ends of the pin body are provided with an inclined surface to enable easy insertion of the tension-loaded members 406A-D into the holes 204A-D, 312A-D while assembling the first housing 110 with the second housing 120. In one embodiment, one of distances between adjacent tension-loaded members 406A-D of the plurality of tension-loaded members 406A-D is less than 30 mm. In another embodiment, at least two solid metallic pins 408 are inserted in positioning holes 410A and 410B formed on the second housing 120 to position the first housing 110 in-line with the second housing 120 as shown in Fig. 6. Further, the positioning holes 410A-B formed on the second housing 120 is complementary to the positioning holes 210A-B formed on the first housing 110.

As explained above, an outer diameter of the plurality of tension-loaded members 406A-D are equal to or larger than an inner diameter of the holes 204A-D, 312A-D. As a result, the co-efficient of friction can be high between outer bodies of the plurality of tension-loaded members 406A-D and inner walls of the holes 204A-D, 312A-D thereby retaining the plurality of tension-loaded members 406A-D inside the holes 204A-D, 312A-D. To insert the plurality of tension-loaded members 406A-D into the holes 204A-D, 312A-D, the plurality of tension-loaded members 406A-D is deformed along their radial direction, so that both ends of the plurality of tension-loaded members 406A-D can be inserted into respective holes 204A-D, 312A-D provided in the first housing 110 and the second housing 120. In one embodiment, each of the tension-loaded members 406A-D have a length of 14 mm. In one example, a portion of the pin body of the plurality of tension-loaded members 406A-D inserted into the holes 204A-D provided in the first housing 110 is larger than the portion of the pin body of the plurality of tension-loaded members 406A-D inserted into the holes 312A-D provided in the second member 120.

All the above-described embodiments are just to explain the present invention while more embodiments and combinations thereof might exist. Hence, the present invention should not be limited to the above-described embodiments alone.

Claims

An electric machine (100), comprising:
a first housing (110) having a first mating surface (202) and adapted to accommodate an electric motor (112);
a second housing (120) having a second mating surface (310) and adapted to accommodate an inverter assembly (122), wherein the first mating surface (202) and second mating surface (310) are complimentary and opposite to each other;
a sealing element (402) disposed between the first mating surface (202) and second mating surface (310), wherein the second housing (120) is adapted to be coupled with the first housing (110); and
a plurality of tension-loaded members (406A-D) provided in holes (204A-D, 312A-D) formed on the first mating surface (202) and the second mating surface (310), while coupling the first housing (110) with the second housing (120).
The electric machine (100) as claimed in claim 1, wherein the sealing element (402) having apertures (404A-D), in-line with the holes (204A-D, 312A-D) formed on the first mating surface (202) and the second mating surface (310) to receive the tension-loaded members (406A-D) there-though.
The electric machine (100) as claimed in claim 1 or 2, wherein the second housing (120) comprises an extending portion (316) extended outward in a radial direction with respect to the second housing (120) and at least one of first and second connectors (318A, 318B) respectively provided on a sidewall (304) of the extending portion (316) of the second housing (120).
The electric machine (100) as claimed in claim 3, wherein the plurality of tension-loaded members (406A-D) is disposed at a circumferential area of the second mating surface (310), corresponding to the at least one of first and second connectors (318A, 318B).
The electric machine (100) as claimed in claim 3, further comprising a plurality of bosses (206A-D, 314A-D) formed on a side of the periphery, corresponding to the at least one of first and second connectors (318A, 318B), of the first mating surface (202) and the second mating surface (310), wherein the holes (204A-D, 312A-D) are formed on the bosses (206A-D, 314A-D).
The electric machine (100) as claimed in any one of claims 1 to 5, wherein the holes (204A-D, 312A-D) are formed on the first mating surface (202) and the second mating surface (310) at a predetermined distance.
The electric machine (100) as claimed in claim any one of claims 1 to 6, wherein at least one of distances between the adjacent holes (204A-D, 312A-D) formed on the first mating surface (202) and the second mating surface (310) is less than 30 mm.
The electric machine (100) as claimed in any one of claims 1 to 7, wherein the sealing element (402) is a rubber coated metallic gasket.
The electric machine (100) as claimed in any one of claims 1 to 8, wherein the plurality of tension-loaded members (406A-D) are spring pins.
The electric machine (100) as claimed in any one of the claims 1 to 9, further comprising at least two pins (408) formed on the second housing (120) to position the first housing (110) in-line with the second housing (120).