Electric oil pump

Abstract

The invention relates to an electric oil pump. The electric oil pump comprises a driving motor, a pump rotor assembly and a shell, the driving motor and the pump rotor assembly are installed in the shell, the driving motor comprises a rotor and a motor shaft which are coaxially connected in a torsion-resistant mode, and the rotor and the pump rotor assembly are distributed at intervals in the axial direction. The motor shaft sequentially penetrates through the rotor and the pump rotor assembly in the axial direction and comprises a first end extending out of the pump rotor assembly back to the rotor in the axial direction. The electric oil pump further comprises a supporting piece installed on one of the first end and the shell, the other one of the first end and the shell comprises a supporting concave part which is concave back to the one in the axial direction, and the supporting piece is inserted into the supporting concave part in the axial direction. The surfaces, making contact with each other, of the supporting piece and the supporting concave part form rotating faces matched with each other and surrounding the rotating axis of the motor shaft, so that the supporting piece can support the motor shaft to rotate around the rotating axis through the surfaces making contact with each other. The electric oil pump has an improved mounting structure.

Description

Technical Field

[0001] This invention relates to the field of oil pump technology. Specifically, this invention relates to an electric oil pump with an improved motor shaft support structure. Background Technology

[0002] An oil pump is a device used to drive fluid flow and generate fluid pressure in a mechanical system. For example, oil pumps are commonly used in modern motor vehicles to drive working fluids used for cooling and lubrication. These oil pumps are typically driven by an electric motor and are therefore called electric oil pumps.

[0003] For example, the mounting structure of electric oil pumps in the prior art can be seen in patent documents such as CN 217682258 U, CN 115628393 A, and CN 116181645 A. In these prior art, the motor shaft is a rotating component with a relatively long axial length, which usually needs to be supported in the housing by at least two bearings. One bearing is located at the end of the drive motor away from the pump rotor assembly, while the other bearing is located between the drive motor and the pump rotor assembly. In order to install the bearing between the drive motor and the pump rotor assembly, a sufficiently large bearing spacing needs to be set between them, thus increasing the axial dimension of the electric oil pump. Moreover, the bearings used here are usually ball bearings, which are relatively large, further increasing the overall size of the electric oil pump. At the same time, ball bearings are expensive, and their installation process is complex: first, the ball bearings need to be installed at both ends of the motor shaft, and then the pump rotor assembly needs to be installed. The pump rotor assembly and the motor shaft need to be interference-fitted. During the installation process, the bearings are subjected to eccentric forces, which may damage the bearings, ultimately leading to noise problems and shortening the service life of the electric oil pump. Summary of the Invention

[0004] Therefore, the technical problem that this invention needs to solve is to provide an improved electric oil pump.

[0005] The aforementioned technical problem is solved by an electric oil pump according to the present invention. The electric oil pump includes a drive motor, a pump rotor assembly, and a housing. The drive motor and the pump rotor assembly are mounted in the housing. The drive motor includes a rotor and a motor shaft coaxially and torsionally connected. The rotor and the pump rotor assembly are spaced apart axially. The motor shaft passes sequentially through the rotor and the pump rotor assembly axially and includes a first end extending axially away from the rotor from the pump rotor assembly. The electric oil pump further includes a support member mounted on one of the first end and the housing. The other end in the housing includes a support recess recessed axially away from the first end. The support member is inserted axially into the support recess. The surfaces of the support member and the support recess that contact each other are respectively formed as matching rotational surfaces about the rotation axis of the motor shaft, such that the support member can support the motor shaft to rotate about the rotation axis through the contacting surfaces. This electric oil pump has a simple motor shaft support structure, is easy to install, and helps reduce production costs.

[0006] According to a preferred embodiment of the invention, in a cross-section passing through the axis of rotation, the width of the contacting surfaces perpendicular to the axis of rotation gradually increases from the bottom of the support recess toward the opening. This facilitates the axial insertion of the support member into the support recess and also provides alignment and axial limiting for the motor shaft.

[0007] According to another preferred embodiment of the invention, the surfaces in contact with each other can define the axial position of the first end relative to the housing, such that the axial end face of the first end does not contact the housing. Since the support and the support recess simultaneously provide radial and axial limiting functions for the motor shaft, the first end can avoid contacting the housing, thereby preventing the housing from obstructing the rotation of the motor shaft.

[0008] According to another preferred embodiment of the invention, the support member can be fixed to either the first end or the housing. The support member is fixedly mounted relative to the first end or the housing, thereby facilitating the provision of stable support for the motor shaft.

[0009] According to another preferred embodiment of the invention, the support member may include a fixed portion and a supporting portion divided along the axial direction, the fixed portion being formed as a cylindrical portion fixedly inserted along the axial direction into one of the first ends and the housing. This facilitates the fixed portion being fixedly mounted to the housing or the motor shaft.

[0010] According to another preferred embodiment of the present invention, the housing may include an axially penetrating mounting hole, and the support member passes through the mounting hole axially and is fixed in the mounting hole. Without disassembling the housing, the axial position of the support member can be adjusted through the penetrating mounting hole, thereby facilitating the adjustment of the fitting clearance between the support member and the support recess.

[0011] According to another preferred embodiment of the invention, the surfaces in contact with each other can be formed as conical surfaces or partially spherical surfaces around the axis of rotation. Such surface structures are simple and easy to process.

[0012] According to another preferred embodiment of the invention, the support member can be formed as a perfect sphere, and the first end and the one in the housing can include a mounting recess that matches the shape of the support member, into which the support member is rotatably mounted. This eliminates the need for a fixed support member, thereby simplifying the installation process.

[0013] According to another preferred embodiment of the present invention, the support recess may include a countersunk hole that is axially recessed from the bottom, and the support member does not contact the inner surface of the countersunk hole. The countersunk hole is usually a process hole formed during the machining of the support recess. This process hole is usually located at the center of the support recess. The countersunk hole has no mating relationship with the support member, which can reduce the machining accuracy requirements and facilitate the installation of the support member.

[0014] According to another preferred embodiment of the invention, the housing may define a receiving cavity for accommodating a first end, a suction cavity for drawing in fluid, and a pumping cavity for pumping out fluid. The first end is axially inserted into the receiving cavity. The suction cavity and the pumping cavity are located radially outside the receiving cavity and are circumferentially separated from each other. The housing also includes a first oil inlet channel and a second oil inlet channel. The first oil inlet channel communicates from the receiving cavity to the suction cavity, and the second oil inlet channel communicates from the receiving cavity to the pumping cavity. The pressure difference between the suction cavity and the pumping cavity drives hydraulic fluid to flow through the receiving cavity around the first end, thereby entering between the contacting surfaces and providing lubrication and cooling to the contact surfaces. Attached Figure Description

[0015] The invention is further described below with reference to the accompanying drawings. In the drawings, the same reference numerals represent elements with the same function. Wherein:

[0016] Figure 1 A longitudinal sectional view of an electric oil pump according to an exemplary embodiment of the present invention is shown;

[0017] Figure 2 Show Figure 1 The image shows a longitudinal sectional view of the electric oil pump at the first end.

[0018] Figure 3 A longitudinal sectional view of an electric oil pump at its first end is shown according to another exemplary embodiment of the present invention.

[0019] Figure 4 A longitudinal sectional view of an electric oil pump at a first end is shown according to yet another exemplary embodiment of the present invention.

[0020] Figure 5 Show Figure 1A perspective view of the front cover of the electric oil pump shown; and

[0021] Figure 6 Show Figure 1 The image shows a longitudinal sectional view of the electric oil pump at the front cover. Detailed Implementation

[0022] The following describes specific embodiments of the electric oil pump according to the present invention with reference to the accompanying drawings. The detailed description and drawings below are provided to illustrate the principles of the invention, and the invention is not limited to the described preferred embodiments; the scope of protection of the invention is defined by the claims.

[0023] According to an embodiment of the present invention, an electric oil pump for driving working fluid and generating fluid pressure is provided. The specific structure of this electric oil pump is described below with reference to the accompanying drawings.

[0024] Figure 1 A longitudinal sectional view of an electric oil pump according to an exemplary embodiment of the present invention is shown. Figure 1 As shown, the electric oil pump mainly includes a drive motor 10, a pump rotor assembly 20, and a housing 30. Additionally, the electric oil pump may also include a controller 40. The drive motor 10, pump rotor assembly 20, and controller 40 are respectively mounted in the housing 30.

[0025] The drive motor 10 includes a stator 11, a rotor 12, and a motor shaft 13. The stator 11 is fixed within a housing 30, and the rotor 12 is coaxially mounted radially inside the stator 11 and is rotatable relative to the stator 11 about a central axis parallel to the axial direction. The motor shaft 13 is coaxially and torsionally connected to the rotor 12, and is specifically fixed radially inside the rotor 12, thereby being rotatable relative to the stator 11 and the housing 30 along with the rotor 12 about a common central axis. Therefore, the common central axis of the rotor 12 and the motor shaft 13 is the axis of rotation O of the rotor 12 and the motor shaft 13. The motor shaft 13 includes two axially opposite ends, namely a first end 13a and a second end 13b. These two ends of the motor shaft 13 protrude axially beyond the rotor 12 to be supported on the housing 30.

[0026] The stator 11 and rotor 12 of the drive motor 10 are axially spaced from the pump rotor assembly 20 and are housed in two different chambers of the housing 30. The chamber housing the stator 11 and rotor 12 can be referred to as the motor chamber, while the chamber housing the pump rotor assembly 20 can be referred to as the pump rotor chamber. The motor chamber and the pump rotor chamber are axially separated by a partition wall in the housing 30. The motor shaft 13 passes axially through the rotor 12 and the pump rotor assembly 20 sequentially, such that a first end 13a of the motor shaft 13 extends axially away from the rotor 12 and a second end 13b extends axially away from the rotor 12. In other words, the first end 13a is axially located on the side of the pump rotor assembly 20 away from the stator 11 and rotor 12, while the second end 13b is axially located on the side of the rotor 12 away from the pump rotor assembly 20. The controller is also axially spaced from the drive motor 10 and located on the side away from the pump rotor assembly 20.

[0027] The housing 30 may be assembled from multiple different parts. For example, in this embodiment, the housing 30 may include a main body 31 and a front end cover 32. The drive motor 10 may be mounted in the main body 31. The front end cover 32 closes one axial end of the main body 31, and the pump rotor assembly 20 is mounted in the pump rotor cavity defined by the front end cover 32 and the main body 31.

[0028] A motor shaft 13 passes through and is driveably connected to the pump rotor assembly 20. The motor shaft 13 is used to transmit the driving torque generated by the drive motor 10 to the pump rotor assembly 20. The pump rotor assembly 20 can be driven by the drive shaft 13 to generate pump suction. The pump rotor assembly 20 can be various pump devices known in the prior art, such as gear pumps, whose specific structures and operating principles for generating pump suction are widely known and will not be described in detail here, nor will they constitute a limitation of the present invention.

[0029] The electric oil pump also includes a support member 50 mounted on one of the first end 13a and the housing 30. The other end 13a and the housing 30 include a support recess 14, which is recessed axially away from the one on which the support member 50 is mounted. The support member 50 is inserted axially into the support recess 14. The surfaces of the support member 50 and the support recess 14 that contact each other around the rotation axis O are respectively formed as matching surfaces of rotation about the rotation axis O of the motor shaft 13, such as conical surfaces, spherical surfaces, ellipsoidal surfaces, drum-shaped surfaces, etc. Matching the shapes of the contact surfaces of the support member 50 and the support recess 14 means that the shapes and dimensions of their contact surfaces are substantially the same, allowing for contact mating with a clearance size within an allowable range. This clearance size ensures that the support member 50 and the support recess 14 can slide relative to each other without interference. In this case, the support member 50 can support the rotation of the motor shaft 13 relative to the housing 30 around the rotation axis O through these contact surfaces.

[0030] The support recess can be formed either in the axial end face of the first end 13a or in the region of the housing 30 facing the axial end face of the first end 13a (particularly on the front end cover 32), as long as the support member 50 is correspondingly mounted. In the embodiment shown in the figures, the support recess 14 is schematically shown as being formed on the first end 13a and the support member 50 is shown as being mounted on the housing 30. Those skilled in the art can interchange this positional relationship according to the principles of the invention.

[0031] To facilitate the axial insertion of the support member 50 into the support recess 14, in a cross-section passing through the rotation axis O, the width of the contacting surfaces of the support member 50 and the support recess 14, perpendicular to the rotation axis O, gradually increases from the bottom of the support recess 14 toward the opening. Simultaneously, this also causes the contacting surfaces of the support member 50 and the support recess 14 to be inclined relative to the axial direction, thus generating both axial and radial pressure components on the contact surfaces. This means that the support member 50 can simultaneously provide axial and radial support forces for the motor shaft 13, thereby not only achieving a centering effect but also defining the axial position of the motor shaft 13 relative to the housing 30. In this case, preferably, the axial position of the first end 13a relative to the housing 30 can be defined solely by the contacting surfaces, such that the axial end face of the first end 13a does not contact the housing 30 (i.e., there is an axial gap between the axial end face of the first end 13a and the housing 30). Therefore, the housing 30 does not directly provide a limiting function for the first end 13a, nor does it obstruct the rotation of the motor shaft 13.

[0032] The connection between the support member 50 and its first end 13a or housing 30 can be fixed. That is, the support member 50 can be fixed to either the first end 13a or the housing 30 where no support recess is formed. For example, in... Figure 2 and Figure 3 In both embodiments, the support member 50 is fixed to the housing 30. Preferably, the support member 50 may include a fixed portion 51 and a supporting portion 52 divided axially, the fixed portion 51 being formed as a cylindrical portion and fixedly inserted axially into the mounting hole 33 of the housing 30. The fixing of the fixed portion 51 to the housing 30 can be achieved by various common methods such as interference fit and bonding. In this case, the mounting hole 33 of the housing 30 can extend axially through the front end cover 32, and the support member 50 passes axially through the mounting hole 33 and is fixed in the mounting hole 33. Thus, even without disassembling the housing 30, the axial position of the support member 50 can be adjusted externally through the mounting hole 33, thereby adjusting the fit clearance between the supporting recess 14 and the support member 50. The supporting portion 52 protrudes beyond the housing 30 and is used for at least partially inserting into the supporting recess 14. The surface of the support member 50 for contacting the supporting recess 14 is formed on the end of the supporting portion 52.

[0033] like Figure 2 and Figure 3 As shown, in different embodiments, the surfaces of the support 50 and the support recess 14 that come into contact with each other can be formed as rotating surfaces of different shapes. For example, in Figure 2 In the illustrated embodiment, the surfaces of the support 50 and the support recess 14 that come into contact with each other are each formed as conical surfaces about the rotation axis O. For example, in... Figure 3 In the embodiment shown, the surfaces of the support 50 and the support recess 14 that come into contact with each other are formed as partially spherical surfaces.

[0034] Alternatively, the connection between the support 50 and its first end 13a or housing 30 can also be non-fixed. For example, in Figure 4 In the illustrated embodiment, the support member 50 is formed as a perfect sphere, and the support recess 14 is correspondingly formed as a partial sphere. The housing 30 has a mounting recess 34 that matches the shape of the support member 50, i.e., a partially spherical mounting recess 34, into which the support member 50 is rotatably mounted. In other words, the perfect spherical support member 50 can rotate simultaneously relative to both the first end 13a and the housing 30. This type of support member 50 is easier to install.

[0035] In any of the above embodiments, regardless of the shape and mounting method of the support member 50, the support recess 14 may include a countersunk hole 15 that is axially recessed from the bottom. The countersunk hole 15 is typically a blind hole located at the center of the bottom of the support recess 14. The countersunk hole 15 is typically a process hole formed during the machining of the support recess 14. The support member 50 may not contact the inner surface of the countersunk hole 15, while the surfaces of the support member 50 and the support recess 14 that contact each other surround the radially outer side of the countersunk hole 15. There is no mating relationship between the countersunk hole 15 in the central region and the support member 50, thereby reducing the requirements for machining accuracy and assembly accuracy.

[0036] Figure 5 A perspective view of the front cover 32 of the housing 30 is shown. Figure 6 A cross-sectional view of the electric oil pump in region 32 of the front cover is shown. Figure 6 As shown, the housing 30 may define a receiving chamber Cr for accommodating the first end 13a, a suction chamber Ci for drawing in fluid, and a pumping chamber Co for pumping out fluid. The suction chamber Ci communicates with the low-pressure chamber of the pump rotor assembly 20, while the pumping chamber Co communicates with the high-pressure chamber of the pump rotor assembly 20. The receiving chamber Cr is a generally cylindrical cavity facing the motor shaft 13 axially, and the first end 13a is inserted into the receiving chamber Cr axially, with a clearance fit between the receiving chamber Cr and the first end 13a. The suction chamber Ci and the pumping chamber Co are located radially outside the receiving chamber Cr and are circumferentially separated from each other. In a preferred embodiment, the housing 30 may have a first oil inlet channel 35 and a second oil inlet channel 36, the first oil inlet channel 35 communicating from the receiving chamber Cr to the suction chamber Ci, and the second oil inlet channel 36 communicating from the receiving chamber Cr to the pumping chamber Co. For example, the first oil inlet channel 35 and the second oil inlet channel 36 can be holes formed in the front end cover 32, or they can be grooves formed on the surface of the front end cover 32 facing the pump rotor assembly 20 and closed by the pump rotor assembly 20. By means of the liquid pressure difference between the suction chamber Ci and the discharge chamber Co, fluid can be driven to flow through the receiving chamber Cr around the first end 13a, thereby entering between the contacting surfaces of the support 50 and the support recess 14, thus providing lubrication and cooling effects to the contact surfaces.

[0037] The electric oil pump according to the present invention achieves an improvement in the support structure for the motor shaft. By cooperating with the support recess and the support member, the installation of complex bearings can be eliminated, thereby reducing the number of components. This support structure not only provides rotational support for the motor shaft but also provides alignment and axial restraint. Furthermore, this support structure has a simple construction, is easy to process and install, and helps reduce production costs.

[0038] While possible embodiments have been described exemplarily in the foregoing description, it should be understood that numerous variations of embodiments exist through combinations of all known and readily conceived technical features and implementation methods. Furthermore, it should be understood that the exemplary embodiments are merely examples and do not in any way limit the scope, application, or construction of the invention. The foregoing description is more intended to provide those skilled in the art with technical guidance for transforming at least one exemplary embodiment, wherein various changes, particularly regarding the function and structure of the components, can be made without departing from the scope of the claims.

[0039] Appendix Label Table

[0040] 10 drive motors

[0041] 11 Stator

[0042] 12 rotors

[0043] 13 Motor Shaft

[0044] 13a First end

[0045] 13b Second End

[0046] 14 Support recess

[0047] 15 Countersunk Hole

[0048] 20 Pump rotor assembly

[0049] 30 Casing

[0050] 31 Main Body

[0051] 32 Front Cover

[0052] 33 mounting holes

[0053] 34 Installation recess

[0054] 35 First oil intake channel

[0055] 36 Second oil intake channel

[0056] 40 Controller

[0057] 50 Support components

[0058] 51 Fixed Part

[0059] 52 Supporting Part

[0060] Ci Inhalation Chamber

[0061] Co pump outlet chamber

[0062] Cr receiving cavity

[0063] O Rotation axis

Claims

1. An electric oil pump comprising a drive motor (10), a pump rotor assembly (20) and a housing (30), the drive motor (10) and the pump rotor assembly (20) being mounted in the housing (30), the drive motor (10) comprising a rotor (12) and a motor shaft (13) coaxially torsionally connected, the rotor (12) being axially spaced apart from the pump rotor assembly (20), the motor shaft (13) axially passing through the rotor (12) and the pump rotor assembly (20) in this order and comprising a first end (13a) axially projecting out of the pump rotor assembly (20) away from the rotor (12), characterized in that the electric oil pump further comprises a support member (50) mounted on one of the first end (13a) and the housing (30), the other of the first end (13a) and the housing (30) comprising a support recess (14) recessed axially away from the one, the support member (50) being axially inserted into the support recess (14), surfaces of the support member (50) and the support recess (14) contacting each other defining respective rotation surfaces matching each other around an axis of rotation (O) of the motor shaft (13) such that the support member (50) can support the motor shaft (13) in rotation around the axis of rotation (O) by the surfaces contacting each other.

2. The electric oil pump according to claim 1, characterized by In a cross section through the axis of rotation (O), a width of the surfaces contacting each other perpendicular to the axis of rotation (O) gradually increases from a bottom of the support recess (14) towards an opening.

3. The electric oil pump of claim 2, wherein The surfaces contacting each other define an axial position of the first end (13a) relative to the housing (30) such that an axial end face of the first end (13a) does not contact the housing (30).

4. The electric oil pump of claim 2, wherein The support member (50) is fixed to the one of the first end (13a) and the housing (30).

5. The electric oil pump of claim 4, wherein The support member (50) comprises an axially divided fixed portion (51) and a support portion (52), the fixed portion (51) being formed to axially fixedly insert into a cylindrical portion of the one of the first end (13a) and the housing (30).

6. The electric oil pump of claim 5, wherein The housing (30) comprises an axially through-going mounting hole (33), the support member (50) axially passing through and being fixed in the mounting hole (33).

7. The electric oil pump of claim 4, wherein The surfaces contacting each other are respectively formed as conical surfaces or as partial spherical surfaces around the axis of rotation (O).

8. The electric oil pump of claim 2, wherein The support member (50) is formed as a regular sphere, the one of the first end (13a) and the housing (30) comprising a mounting recess (34) matching the shape of the support member (50), the support member (50) being rotatably mounted into the mounting recess (34).

9. The electric oil pump of claim 2, wherein The support recess (14) comprises a counterbore (15) axially recessed from the bottom, the support member (50) not contacting an inner surface of the counterbore (15).

10. The electric oil pump according to any one of claims 1 to 9, characterized by The casing (30) defines a receiving cavity (Cr) for housing the first end (13a), which is inserted axially in the receiving cavity (Cr), a suction cavity (Ci) for sucking in fluid and a delivery cavity (Co) for pumping out fluid, which are located radially outside the receiving cavity (Cr) and are separated from each other circumferentially, the casing (30) further comprising a first oil lead channel (35) and a second oil lead channel (36), the first oil lead channel (35) communicating from the receiving cavity (Cr) to the suction cavity (Ci), the second oil lead channel (36) communicating from the receiving cavity (Cr) to the delivery cavity (Co).

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