An electric drive unit with multiple coolant channels and a single cover for the same

Abstract

The present invention relates to an electric drive unit (100) for a vehicle. The electric drive unit (100) comprises at least one electrical machine, at least one power electronics unit connected to the at least one electrical machine, at least one transmission coupled to the at least one electrical machine, and a housing (102) enclosing the at least one electrical machine, the at least one power electronics unit and the at least one transmission. The housing (102) comprises at least two coolant channels accessible from a side opening (104) of the housing (102), characterized in that, a single cover (106) for each of the at least two coolant channels, the single cover 106 is fixable on the housing (102) to close the side opening (104). The single cover (106), comprising an integrated rotor position sensor, is wet sealed with the housing (102).

Description

Title of the invention:AN ELECTRIC DRIVE UNIT WITH MULTIPLE COOLANTCHANNELS AND A SINGLE COVER FOR THE SAME Applicants: a. Name: Bosch Global Software Technologies Private LimitedNationality: INDIAAddress: 123, Industrial Layout, Hosur Road, Koramangala, Bangalore- 560095, Karnataka, India b. Name: Robert Bosch GmbHNationality: GERMANYAddress: Postfach 30 02 20, 0-70442, Stuttgart, GermanyComplete specification: The following specification particularly describes the invention and the manner in which it is to be performed.Field of the invention:

[0001] The present disclosure relates to an electric drive unit for a vehicle, and particularly to an electric drive unit with multiple coolant channels and a single cover for the same.Background of the invention:

[0002] An electric drive unit is a primary driving unit for an electric vehicle, it converts electrical energy stored in the batteries into motion. An electric drive unit is also called an electric axle or an eAxle and it comprises of three main components: an electrical machine, a power electronics unit, and a transmission. The components of the electric drive unit are assembled in a housing and closed with a cover. A cooling system is deployed in electric vehicles to keeps the temperature of the electric drive unit in optimal condition. The cooling system maintains the temperature in optimal condition using coolants and internal coolant channels in the housing.

[0003] WO19154685 Al discloses an electric drive unit for a motor vehicle, which has a vehicle cooling system, wherein the electric drive unit has an electric machine, a transmission operatively connected to the electric machine, and power electronics for controlling the electric machine, wherein the components of the electric drive unit, in the assembled state, form an integrated cooling system having a common cooling fluid inlet and a common cooling fluid outlet, wherein the integrated cooling system is connected to the one common cooling fluid inlet and to the one common cooling fluid outlet on a vehicle cooling system.

[0004] The problem with existing electric drive units is two-fold. Firstly, for the electric drive units with multiple coolant channels, the coolants operate under such varying temperature and pressure that more than one cover and usually same as the number of coolants are required to close the open-end of the housing from wherethe internal coolant channels are accessible. Secondly, the choice of material for the housing and the cover, and the manner of closing them poses various problems. The problem with closing an aluminum housing with an aluminum cover using wet sealing is that it poses a higher probability of corrosion, and increased cost because of casting and machining of the aluminum cover. Whereas the problem encountered while enclosing the aluminum housing with a cover using solid seal is that it poses higher possibility of leakage, cooling system failure, and increased cost because of the complexity in manufacturing of a profiled solid seal.

[0005] The present invention solves all the above-mentioned problems in a manner as described in the claims.Brief description of the accompanying drawings:

[0006] An embodiment of the disclosure is described with reference to the following accompanying drawings.

[0007] Fig. 1 illustrates exploded view of an electric drive unit, according to an embodiment of the present invention, and

[0008] Fig. 2 illustrates an internal surface (A) of a single cover and an external surface (B) of the single cover, according to an embodiment of the present invention.Detailed description of the embodiments:

[0009] Fig. 1 illustrates exploded view of an electric drive unit, according to an embodiment of the present invention. The electric drive unit 100 of a vehicle comprises at least one electrical machine, at least one power electronics unit connected to the at least one electrical machine, at least one transmission coupled to the at least one electrical machine, and a housing 102 enclosing the at least one electrical machine, the at least one power electronics unit and the at least one transmission. Further, the housing 102 comprises at least two coolant channelsaccessible from a side opening 104 of the housing 102, characterized in that, a single cover 106 for each of the at least two coolant channels is provided. The single cover 106 is fixable on the housing 102 to close the side opening 104. The term “the single cover 106” also refers to the cover or the B-shield cover of the electric drive unit 100. In addition, the housing 102 may be of a single piece structure or combination of multiple pieces to enclose the electrical machine, the at least one power electronics unit and the at least one transmission.

[0010] In an embodiment of the present invention, the at least two coolant channels comprise two coolant channels, namely, a first coolant channel and a second coolant channel. In another embodiment of the present invention, a first coolant circulates in the first coolant channel to cool the at least one power electronics and a second coolant circulates in the second coolant channel to cool the at least one electrical machine and the at least one transmission. In yet another embodiment of the present invention, the first coolant is a mixture of water and glycol, and the second coolant is oil. In yet another embodiment of the present invention, the first coolant is a mixture of fifty percent water and fifty percent glycol, and the second coolant is transmission oil. In yet another embodiment of the present invention, the second coolant is transmission oil BluEV EG EDF 6933. In yet another embodiment of the present invention, at least one coolant flows through the at least two coolant channels.

[0011] In an embodiment of the present invention, the first coolant and the second coolant have varying operating temperature and pressure. In another embodiment for the present invention, the service temperature for the first coolant is between minus forty degree Celsius (-40°C) and ninety degrees Celsius (90°C). In yet another embodiment of the present invention, the operating pressure for the first coolant is two-point five bar (2.5 bar). In yet another embodiment for the present invention, the service temperature for the second coolant is hundred degrees Celsius (100°C). In yet another embodiment of the present invention, the operating pressure for the second coolant is atmospheric pressure.

[0012] In an embodiment of the present invention, the first coolant flows through a water jacket structure of the first coolant channel to cool the at least one power electronics. In another embodiment of the present invention, the second coolant is splashed across the second coolant channel to cool the at least one electrical machine along with its stator windings and the at least one transmission. In yet another embodiment of the present invention, both of the first coolant channel and the second coolant channel are of water jacket type or conduits which are spread across the electric drive unit 100.

[0013] Fig. 2 illustrates an internal surface (A) of the single cover and an external surface (B) of the single cover, according to an embodiment of the present invention. The internal surface of the single cover 106 illustrated by Fig. 2A faces the electric drive unit 100 during assembly and the external surface of the single cover 106 illustrated by Fig. 2B faces away from the electric drive unit 100 during assembly. In an embodiment of the present invention, the internal surface of the single cover 106, which faces towards the housing 102 of the electric drive unit 100, comprises at least one pocket 108. In another embodiment of the present invention, the at least one pocket 108 comprises guide ribs. In yet another embodiment of the present invention, the at least one pocket 108 accommodates at least one sensor 110. The guide ribs of the at least one pocket 108 helps in assembly and accommodating the at least one sensor 110 in the at least one pocket 108. In yet another embodiment of the present invention, the at least one sensor 110 is a rotor position sensor. In yet another embodiment of the present invention, the at least one sensor 110 comprises two sensors, namely a rotor position sensor and a temperature sensor.

[0014] In an embodiment of the present invention, the at least one sensor 110 is integrated into the single cover 106 by accommodating the at least one sensor 110 within the at least one pocket 108 with the help of the guide ribs. In another embodiment of the present invention, the at least one sensor 110 and the at leastone pocket 108 comprise snap-fit assembly for interlocking. In yet another embodiment of the present invention, the at least one sensor 110 once accommodated / interlocked within the at least one pocket 108 of the single cover 106 is epoxy potted. The epoxy potting of the at least one sensor 110 within the single cover 106 protects the at least one sensor 110 from the second coolant and the shocks / vibrations.

[0015] In an embodiment of the present invention, the at least one sensor 110 is integrated into the single cover 106 using an insulation displacement connection. In another embodiment of the present invention, as illustrated in Fig. 2, the at least one sensor 110 and an insulation displacement connector 114 are comprised on the internal surface of the single cover 106. In yet another embodiment of the present invention, the male connector for the insulation displacement connector 114, on the internal surface of the single cover 106, is comprised on the housing 102 to complete the connection when the cover 106 closes the side opening 104. In yet another embodiment of the present invention, the insulation displacement connector 114 is comprised on at least one of the internal surface and the external surface of the single cover 106 respectively.

[0016] As disclosed above, the at least two coolant channels are accessible from the side opening 104 of the housing 102 and the single cover 106 closes the side opening 104 and thereby closes the at least two coolant channels. The side opening 104 needs to be closed during operation. In an embodiment of the present invention, the internal surface of the single cover 106, facing the housing 102, comprises protrusions 112. In another embodiment of the present invention, the protrusions 112 abut with walls 116 of the at least two coolant channels after assembly in such a manner that coolants are retained in respective the at least two coolant channels. In yet another embodiment of the present invention, the protrusions 112 of the single cover 106 retain the first coolant and the second coolant in their respective coolant channels and prevent them from mixing.

[0017] In an embodiment of the present invention, the housing 102 is made of a first material and the single cover 106 is made of a second material. In another embodiment of the present invention, the first material is a metal selected from Aluminum and the second material is a non-metal selected from a Plastic. In yet another embodiment of the present invention, the first material is an aluminum alloy AlSil2Cul(Fe) and the second material is a polyamide plastic PA66GF30. Other metals known in the art are also usable as the first material as required.

[0018] In an embodiment of the present invention, the single cover 106 is wet sealed with the housing 102. In another embodiment of the present invention, the housing 102 and the single cover 106 comprise a crosshatch design to enhance wet sealing. In yet another embodiment of the present invention, the single cover 106 is wet sealed with the housing 102 using a silicone sealant material. In yet another embodiment of the present invention, the housing 102 and the single cover 106 are pre-cleaned before wet sealing by laser cleaning the housing 102 and plasma plus treating the single cover 106 respectively.

[0019] In an embodiment of the present invention, the housing 102 and the single cover 106 comprise at least one positioning hole respectively which helps in assembly during wet sealing of the single cover 106 with the housing 102. In another embodiment of the present invention, the single cover 106 and the housing 102 are fastened after wet sealing using at least one of screws, nuts-bolts, rivets, and other kinds of fasteners. In yet another embodiment of the present invention, an air tightness test is conducted to check for leakages after wet sealing the single cover 106 with the housing 102.

[0020] According to the present invention, an electric drive unit 100 with multiple coolant channels and a single cover 106 for the same is disclosed. The present invention solves the problems discussed above. The present invention provides the single cover 106 for closing the side opening 104 and the at least two coolant channels of the housing 102 despite the varying operating temperature and pressureof the coolants. The present invention by wet sealing the single cover 106 made of the second material and the housing 102 made of the first material reduces the possibility of corrosion, the possibility of leakages and the manufacturing cost. The present invention provides a novel electric drive unit 100 for vehicles which reduces the design complexity, eases the assembly process, and enhances the cooling efficiency using the above-discussed structure and sealing arrangement.

[0021] It should be understood that the embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modification and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

Claims

We claim:

1. An electric drive unit (100) of a vehicle, said electric drive unit (100) comprises:- at least one electrical machine;- at least one power electronics unit connected to said at least one electrical machine;- at least one transmission coupled to said at least one electrical machine; and- a housing (102) enclosing said at least one electrical machine, said at least one power electronics unit and said at least one transmission, wherein said housing (102) comprises at least two coolant channels accessible from a side opening (104) of said housing (102), characterized in that, a single cover (106) for each of said at least two coolant channels, said single cover (106) is fixable on said housing (102) to close said side opening (104).

2. The electric drive unit (100) as claimed in claim 1, wherein an internal surface of said single cover (106), which faces towards said housing (102), comprises at least one pocket (108).

3. The electric drive unit (100) as claimed in claim 2, wherein said at least one pocket (108) comprises guide ribs, wherein said at least one pocket (108) accommodates at least one sensor (110).

4. The electric drive unit (100) as claimed in claim 3, wherein said at least one sensor (110) is a rotor position sensor.

5. The electric drive unit (100) as claimed in claim 1, wherein said at least two coolant channels comprise two coolant channels, namely, a first coolant channel and a second coolant channel.

6. The electric drive unit (100) as claimed in claim 1, wherein said internal surface of said single cover (106), facing said housing (102), comprises protrusions (112), wherein said protrusions (112) abut with walls (116) of said at least two coolant channels after assembly in such a manner that coolants are retained in respective said at least two coolant channels.

7. The electric drive unit (100) as claimed in claim 1, wherein said housing (102) is made of a first material and said single cover (106) is made of a second material.

8. The electric drive unit (100) as claimed in claim 7, wherein said first material is a metal selected from Aluminum and said second material is a non-metal selected from a Plastic.

9. The electric drive unit (100) as claimed in claim 1, wherein said single cover (106) is wet sealed with said housing (102).

10. The electric drive unit (100) as claimed in claim 9, wherein said housing (102) and said single cover (106) comprise a crosshatch design to enhance wet sealing, wherein said single cover (106) is wet sealed with said housing (102) using a silicone sealant material, wherein said housing (102) and said single cover (106) are pre-cleaned before wet sealing by laser cleaning said housing (102) and plasma plus treating said single cover (106) respectively.

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