Electric fluid pump device

Abstract

The invention is directed to an electric fluid pump device (10) in particular for a vehicle comprising a pump housing (12) defining a pumping chamber (14) and a motor chamber (16), the pumping chamber (14) and the motor chamber (16) being fluidically connected to each other, an electric drive motor (30) with a motor rotor (32) and a motor stator (34), the electric drive motor (30) being arranged within the motor chamber (16), an electronics chamber (18) for housing the power electronic components (40) of the electric drive motor (30), a separation wall (20) for fluidically separating the motor chamber (16) from the electronics chamber (18), wherein at least one contact element (36) extends through a corresponding contact element opening (22) within the separation wall (20), the contact element (36) providing an electric contact between the power electronic components (40) and the motor stator (34), and a sealing means (50) for sealing a gap (24) between the contact element (36) and the contact element opening (22), wherein the sealing means (50) is held in its position by a separate hold-down element (54). The sealing means (50) seals the electronics chamber (18) against the fluid within the fluid-filled motor chamber (16) allowing the motor stator (34) to be completely submerged within the fluid.

Description

[0001] D E S C R I P T I O N

[0002] Electric fluid pump device

[0003] The invention is directed to an electric fluid pump device in particular for a vehicle.

[0004] Such an electric fluid pump device typically comprises an electronically commutated electric drive motor with a motor rotor and a motor stator being arranged within a motor chamber defined by the pump housing of the electric fluid pump device. The motor chamber is fluidically connected to the pumping chamber and is therefore flooded with the fluid being pumped within the pumping chamber, wherein the fluid enters the motor chamber via said fluidic connection. The fluid, which is preferably oil, thereby cools the motor rotor and the motor stator directly by circulating through the motor chamber and around the electric drive motor.

[0005] The pump housing of the electric fluid pump device typically comprises an electronics chamber which houses the power electronic components for driving the electric drive motor. The electronics chamber is fluidically separated from the motor chamber to protect the power electronic components from the fluid within the motor chamber. For driving the electric drive motor, an electric connection between the motor stator and the power electronic components is required, which is typically provided by a contact element, for example, a wire or any other electrically conducting component. The contact element extends from the electronics chamber into the motor chamber through a contact element opening.

[0006] It is an object of the present invention to provide a cost-efficient and reliable sealing between the motor chamber and the electronics chamber. This object is achieved by an electric fluid pump device according to the invention with the features of main claim 1.

[0007] An electric fluid pump device according to the invention in particular for a vehicle comprises a pump housing defining a pumping chamber and a motor chamber, the pumping chamber and the motor chamber being fluidically connected to each other, for example, via a connection channel within the pump housing. The motor chamber is therefore filled with the fluid being pumped through the pumping chamber. The electric fluid pump device further comprises an electric drive motor with a preferably permanent- magnetic motor rotor and a motor stator preferably with a core made of a laminated sheet metal stack. The electric drive motor is a brushless electronically commutated electric motor which is arranged within the motor chamber, so that both the motor rotor and the motor stator are in a direct fluidic contact with the fluid within the motor chamber. The fluidic connection between the pumping chamber and the motor chamber is arranged such that the fluid circulates within the motor chamber around the electric drive motor and thereby dissipates the heat being generated by the motor rotor and the motor stator.

[0008] The electric fluid pump device further comprises an electronics chamber for housing the power electronic components of the electric drive motor, the power electronic components being preferably arranged at a printed circuit board. The electronics chamber is defined by the pump housing and is arranged adjacent to the motor chamber. A separation wall fluidically separates the motor chamber from the electronics chamber and is therefore in a direct fluidic contact with the fluid within the motor chamber. By arranging the power electronic components and / or the printed circuit board relatively close to the separation wall, the fluid additionally dissipates the heat being generated by the power electronic components and being transferred to the separation wall. The separation wall can be an integral part of the pump housing and / or a separate component being mounted within the pump housing.

[0009] A contact element extends through a corresponding contact element opening within the separating wall and therefore extends from the electronics chamber into the motor chamber. The contact element is made of an electrically conductive material and provides an electric contact between the power electronic components and the motor stator to energise the coils of the motor stator and to thereby drive the electric drive motor.

[0010] The dimensions of the contact element opening and the contact element are defined such that a gap is defined between the contact element and the contact element opening. The contact element opening is preferably a borehole within the separating wall, through which the contact element extends, wherein the inner dimension of the contact element opening is larger than the outer dimension of the contact element so that the gap extends radially and axially between the inner radial surface of the contact element opening and the outer radial surface of the contact element. The electric fluid pump device comprises a sealing means for sealing the gap between the contact element and the contact element opening. The sealing means closes the gap between the contact element in the contact element opening so that no fluidic connection is provided between the electronics chamber and the motor chamber. As a result, the sensitive power electronic components are protected from the fluid within the motor chamber.

[0011] The electric fluid pump device further comprises a separate hold-down element for axially holding the sealing means in its position. The hold-down element is arranged such, that the sealing means tightly contacts the sealing surfaces, the hold-down element securing the sealing means axially and radially against any displacement. The hold-down element is substantially pot-shaped, wherein the sealing means extends into the pot part of the hold-down element so that the hold-down element at least partially radially surrounds the sealing means. The sealing means seals the electronics chamber against the fluid within the fluid-filled motor chamber allowing the motor stator to be completely submerged within the fluid. As a result, the motor stator is efficiently cooled by the fluid circulating through the motor chamber.

[0012] In a preferred embodiment of the invention, the sealing means is arranged within a corresponding cavity, the cavity defining an axial stop surface for the sealing means. The sealing means is pushed against the axial stop surface by the hold-down element, the axial stop surface thereby defining a first sealing surface. A second sealing surface is defined by the contact element, wherein the sealing means completely encloses and tightly contacts the outer surface of the contact element. The sealing means is preferably made of a plastic or rubber material, which can be liquid during the assembly process. By pushing the sealing means into the cavity and against the axial stop surface, a slight compression of the sealing means material is provided which additionally increases the sealing effect. In case of a liquid application of the sealing means material during the assembly process, the hold-down element compresses the liquid sealing means to thereby degas the material and to completely fill the cavity before the material becomes solidified.

[0013] In another preferred embodiment of the invention, the cavity is defined rotationally symmetrical. The cavity is therefor shaped as a type of countersunk hole, which can be defined cylindrically, conically or a combination of both. Accordingly, the sealing means is also defined rotationally symmetrical and tightly fits in the cavity.

[0014] In another preferred embodiment of the invention, the cavity comprises a conical wall section which tapers towards the axial stop surface, wherein the sealing means is pushed in tapering direction of the conical wall section by the hold-down element. Thereby, the axial compression of the sealing means additionally provides a radial compression which pushes the sealing means radially inwards against the contact element resulting in a relatively tight sealing contact between the sealing means and the contact element.

[0015] In another preferred embodiment of the invention, the separation wall is at least partially defined by the heat-transfer element. The heat-transfer element is made of a material with relatively good thermal conducting properties, whereas the pump housing can be made of a material with relatively poor thermal conducting properties. The heat-transfer element is at one side in a direct contact with the fluid within the motor chamber and on the other side in a thermally conductive contact with the power electronic components or the printed circuit board so that the heat being generated by the power electronic components can be dissipated relatively efficiently via the heat-transfer element and the fluid within the motor chamber. As a result, the pump housing can be made of a relatively cost-efficient material.

[0016] In another preferred embodiment of the invention, the separation wall is at least partially defined by the pump housing. The pump housing is typically made of a relatively light and cost-efficient material, for example a plastic material. The separation wall can, for example, be partially made of the lightweight pump housing material and be partially made of a relatively heavy metallic material with proper thermally conducting properties to avoid a relatively high total weight of the electric fluid pump device.

[0017] In another preferred embodiment of the invention, the cavity is arranged within the pump housing part of the separation wall. Since the pump housing is made of a relatively lightweight material, the pump housing part of the separation wall can be designed relatively thick in some sections, to provide enough space for the cavity, without relevantly increasing the total weight of the electric fluid pump device. Furthermore, the manufacturing of the cavity is relatively cost-efficient. In another preferred embodiment of the invention, both the sealing means and the hold-down element are arranged axially between the pump housing part of the separation wall and the heat-transfer element. Thereby, the sealing means and the hold-down element are compressed between the heat-transfer element and the pump housing to define a relatively tight sealing between the electronics chamber and the motor chamber.

[0018] In another preferred embodiment of the invention, the sealing means is made of a silicon-based material. The silicon-based material is preferably liquid during the assembly process of the sealing means, wherein the silicon-based material is filled in the cavity in the liquid state. The holddown element is then pushed into the cavity to compress the liquid silicon- based material before it becomes solidified to push the liquid silicon-based material in every corner of the cavity and also into the gap between the contact element opening and the contact element to guarantee a hermetically sealing of the electronics chamber.

[0019] In another preferred embodiment of the invention, the heat-transfer element is in a heat transferring contact with the power electronic components or with a printed circuit board being provided with the power electronic components. The heat-transfer element is also in a direct contact with the fluid within the motor chamber so that a relatively large amount of heat can be dissipated from the power electronic components to the fluid within the motor chamber. The circulation of the fluid within the motor chamber and through the pumping chamber allows a relatively quick heat removal from the pump.

[0020] In another preferred embodiment of the invention, the printed circuit board is mounted onto the heat-transfer element by using a thermally conductive adhesive. The thermally conductive adhesive provides a relatively good heat transfer between the printed circuit board and the heat-transfer element which results in a relatively efficient heat dissipation of the heat being generated by the power electronic components.

[0021] An embodiment of the present invention is described with reference to the enclosed drawings, wherein figure 1 shows a cross-sectional view along the rotational axis of an electric fluid pump device according to the invention, and figure 2 shows an enlarged sectional view of the electric fluid pump device of figure 1 which shows the sealing element with the cavity in detail.

[0022] Figure 1 shows an electric fluid pump device 10 for a vehicle, for example, for supplying an automatic transmission of a passenger vehicle with oil. The electric fluid pump device 10 comprises a multipart pump housing 12 which is made of a plastic material, the pump housing 12 defining a pumping chamber 14 and a motor chamber 16. A pump rotor 17, for example a pump rotor 17 of a gerotor pump, is arranged within the pumping chamber 14 for pumping oil through the pumping chamber 14. The motor chamber 16 is arranged axially adjacent to the pumping chamber 14. A brushless electric drive motor 30 is arranged within the motor chamber 16, the electric drive motor 30 comprising a permanent-magnetic motor rotor 32 and a motor stator 34 with a core made of a laminated sheet metal stack (not shown). The motor stator 34 comprises several stator coils 38 being provided with stator windings 37.

[0023] The motor rotor 32 and the pump rotor 17 are co-rotatably connected via a hollow driveshaft 15 so that the electric drive motor 30 drives the pump rotor 17. The hollow driveshaft 15 comprises a backflow channel 151 extending axially completely through the driveshaft 15, wherein the first connection channel 151 is fluidically connected to a high-pressure zone HP of the pumping chamber 14 via a second connection channel 191 within a pump housing cover 19 which axially closes the pumping chamber 14. The first connection channel 151 and the second connection channel therefore fluidically connect the high-pressure zone HP of the pumping chamber 14 with the motor chamber 16. The pumping chamber 14 and the motor chamber 16 are further fluidically connected to each other via a backflow channel 121 within the pump housing 12 through which the oil flows back from the motor chamber 16 to a low-pressure zone LP of the pumping chamber 14 so that a forced oil flow flows from the high-pressure zone HP of the pumping chamber 14 through the motor chamber 16 to the low- pressure zone LP of the pumping chamber 14. As a result, the oil permanently circulates from the pumping chamber 14 through the motor chamber 16 and back to the pumping chamber 14 during the operation of the electric fluid pump device 10.

[0024] The electric fluid pump device 10 further comprises an electronics chamber 18 for housing the power electronic components 40 of the electric drive motor 30. The electronics chamber 18 is defined by the pump housing 12 and is arranged axially adjacent to the motor chamber 16. The electronics chamber 18 is fluidically separated from the motor chamber 16 by a separation wall 20 which is partially defined by the pump housing 12 and by a disk-shaped heat-transfer element 60. The pump housing part 11 of the separation wall 16 supports the heat-transfer element 60, wherein a sealing ring 70 seals the joint between the pump housing part 11 of the separation wall 20 and the heat-transfer element 60. The power electronic components 40 are supported by a printed circuit board 45 which is arranged in parallel to the separation wall 20 in particular to the heattransfer element 60 to have a relatively large heat transfer surface.

[0025] To provide a relatively large heat transfer from the power electronic components 40 at the printed circuit board 45 to the heat-transfer element 60, a thermally conductive adhesive 65 is arranged between the heattransfer element 60 and the printed circuit board 45. The heat-transfer element 60 is in particular in the radial center of the electric fluid pump device 10, i.e. at the electronics-chamber-sided axial end of the driveshaft 15 in a direct contact with the oil within the motor chamber 16. The electronics-chamber-sided axial end of the driveshaft 15 is arranged axially is directly opposite to the heat-transfer element 60 so that the oil flow which circulates through the motor chamber 16 inevitably flows radially along the heat-transfer element 60 and thereby absorbs the heat which is transferred from the power electronic components 40 via the printed circuit board 45 and the thermally conductive adhesive 65 to the heat-transfer element 60. The circulating oil in the motor chamber 16 thereby dissipates the heat from the power electronic components 40 and also from the electric drive motor 30.

[0026] The separation wall 20, in particular the pump housing part 11 of the separation wall 20 is provided with a cylindrical contact element opening 22. A contact element 36 extends axially from the electronics chamber 18 into the motor chamber 16 through the contact element opening 22 and also through corresponding concentric openings in the heat-transfer element 60 and in the printed circuit board 45. The contact element electrically connects the power electronic components 40 at the printed circuit board 45 with the stator windings 37 of the stator coils 38 to energise the stator coils 38 and to thereby drive the electric drive motor 30.

[0027] A ring-shaped gap 24 is defined between the inner radial wall of the contact element opening 22 and the outer radial wall of the contact element 36, which figure 2 shows in detail. A sealing means 50, made of a silicone-based material, is provided for sealing the gap 24 between the contact element 36 and the contact element opening 22. The sealing means 50 is provided with a central opening through which the contact element 36 completely extends. The sealing means 50 is arranged within a corresponding rotationally symmetrical cavity 26 with a cylindrical wall section 25 and a conical wall section 27. The conical wall section 27 is arranged such that it tapers in direction of the gap 24.

[0028] A separate pot-type hold-down element 54 holds the sealing means 50 in its position. The sealing means 50 is pushed by the hold-down element 45 against an axial stop surface 28 of the cavity 26, i.e., the sealing means 50 is pushed in tapering direction of the conical wall section 27 of the cavity 26. The outer diameter of the hold-down element 54 is larger than the diameter of the opening within the heat-transfer element 60 through which the contact element 36 extends. The heat-transfer element 60 is mounted such, that it biases the hold-down element 54 against the sealing means 52 to compress the sealing means 50 within the cavity 26 and to press the sealing means 50 against the axial stop surface 28 which is a first sealing surface between the pump housing 12 and the sealing means 50.

[0029] The sealing means 50 tightly encloses the contact element 36 completely, wherein the axial compression of the sealing means 50 in tapering direction of the conical wall section 27 results in a radial compression of the sealing means 50 and of its central opening which pushes the sealing means against the contact element 36 which additionally increases the sealing effect. As a result, the gap 24 between the contact element opening 22 and the contact element 36 is completely sealed so that the electronics chamber 18 with the sensitive power electronic components 40 is hermetically sealed and therefore protected from the oil within the motor chamber 16. io

Claims

C L A I M S1. Electric fluid pump device (10) in particular for a vehicle, comprising a pump housing (12) defining a pumping chamber (14) and a motor chamber (16), the pumping chamber (14) and the motor chamber (16) being fluidically connected to each other, an electric drive motor (30) with a motor rotor (32) and a motor stator (34), the electric drive motor (30) being arranged within the motor chamber (16), an electronics chamber (18) for housing the power electronic components (40) of the electric drive motor (30), a separation wall (20) for fluidically separating the motor chamber (16) from the electronics chamber (18), wherein at least one contact element (36) extends through a corresponding contact element opening (22) within the separation wall (20), the contact element (36) providing an electric contact between the power electronic components (40) and the motor stator (34), and a sealing means (50) for sealing a gap (24) between the contact element (36) and the contact element opening (22), wherein the sealing means (50) is axially held in its position by a separate holddown element (54).

2. Electric fluid pump device (10) according to claim 1, wherein the sealing means (50) is arranged within a corresponding cavity (26), the cavity (26) defining an axial stop surface (28) for the sealing means (24), wherein the sealing means (50) is pushed against the axial stop surface (28) by the hold-down element (54).

3. Electric fluid pump device (10) according to claim 2, wherein the cavity (26) is defined rotationally symmetrical.

4. Electric fluid pump device (10) according to claim 3, wherein the cavity (26) comprises a conical wall section (27) which tapers towards the axial stop surface (28), wherein the sealing means (50) is pushed in tapering direction of the conical wall section (27) by the hold-down element (54).

5. Electric fluid pump device (10) according to one of the preceding claims, wherein the hold-down element (54) is biased by a separate heat-transfer element (60) pushing the hold-down element (54) axially against the sealing means (50).

6. Electric fluid pump device (10) according to claim 5, wherein the separation wall (20) is at least partially defined by the heat-transfer element (60).

7. Electric fluid pump device (10) according to one of the preceding claims, wherein the separation wall (20) is at least partially defined by the pump housing (12).

8. Electric fluid pump device (10) according to claim 7, wherein the cavity (26) is arranged within the pump housing part (11) of the separation wall (20).

9. Electric fluid pump device (10) according to one of the claims 7 or 8, wherein both the sealing means (50) and the hold-down element (54) are arranged axially between the pump housing part (11) of the separation wall (20) and the heat-transfer element (60).

10. Electric fluid pump device (10) according to one of the preceding claims, wherein the sealing means (50) is made of a silicon-based material.

11. Electric fluid pump device (10) according to one of the preceding claims, wherein the heat-transfer element (60) is in a heat transferring contact with the power electronic components (40) or with a printed circuit board (45) being provided with the power electronic components (40).

12. Electric fluid pump device (10) according to claim 11, wherein the printed circuit board (45) is mounted onto the heat-transfer element (60) by using a thermally conductive adhesive (65).

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