Electric oil pump

Abstract

An electric oil pump, comprising a drive electric motor (10), a pump rotor assembly (20) and a housing (30), wherein the drive electric motor (10) and the pump rotor assembly (20) are mounted inside the housing (30); the drive electric motor (10) comprises a rotor (12) and an electric motor shaft (13), which are coaxially connected in an anti-torsion manner; and the rotor (12) and the pump rotor assembly (20) are axially spaced apart, and the electric motor shaft (13) axially runs through the rotor (12) and the pump rotor assembly (20) in sequence. The electric oil pump further comprises a first bearing (40). The electric motor shaft (13) comprises a first end (13a) which axially faces away from the rotor (12) and extends out from the pump rotor assembly (20), and the first end (13a) is rotatably supported on the housing (30) by means of the first bearing (40). The electric oil pump can be reduced in size, thereby facilitating installation, and being stable and reliable.

Description

Electric oil pump Technical Field

[0001] The present invention relates to the technical field of oil pumps, and in particular to an electric oil pump. Background Art

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

[0003] CN 116529487 A discloses an electric oil pump with a typical structure. This 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 separate chambers within the housing and arranged axially. The motor shaft of the drive motor is drivingly connected to the pump rotor assembly to output a driving torque to the pump rotor assembly. The pump rotor assembly rotates, generating pump suction.

[0004] In the prior art, the motor shaft is a rotating component with a long axial length, and usually needs to be supported in the housing by at least two bearings. One of the bearings is arranged at the end of the drive motor away from the pump rotor assembly, and the other bearing is arranged between the drive motor and the pump rotor assembly. In order to install the bearings between the drive motor and the pump rotor assembly, a sufficiently large bearing spacing needs to be set between the two, which causes the axial size of the electric oil pump to increase. Moreover, the bearings used here are usually ball bearings, which are relatively large in size, further increasing the overall size of the electric oil pump. At the same time, ball bearings are expensive and their installation process is complicated: first, the ball bearings need to be installed at both ends of the motor shaft, and then the pump rotor assembly is installed. The pump rotor assembly and the motor shaft need to be interference fit. During the installation process, the bearings are subjected to eccentric force, which may damage the bearings, ultimately causing noise problems and shortening the service life of the electric oil pump.

[0005] Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide an improved electric oil pump.

[0007] The above technical problems are 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 installed in the housing. The drive motor includes a rotor and a motor shaft that are coaxially connected to prevent rotation. The rotor and the pump rotor assembly are spaced apart along the axial direction, and the motor shaft passes through the rotor and the pump rotor assembly in sequence along the axial direction. Among them, the electric oil pump also includes a first bearing. The motor shaft includes a first end that extends axially away from the rotor and extends out of the pump rotor assembly. The first end is rotatably supported on the housing through the first bearing. By changing the support position of the bearing close to the pump rotor assembly relative to the motor shaft, the space located axially outside the pump rotor assembly can be used to install the first bearing, thereby reducing the axial size of the electric oil pump and improving the compactness of the structure.

[0008] According to a preferred embodiment of the present invention, the housing may include a main body and a pump head cover. The main body may include a pump rotor cavity that is open axially away from the rotor and accommodates the pump rotor assembly. The pump head cover may be fixed to the main body axially adjacent to the pump rotor assembly to thereby enclose the pump rotor cavity. The first end of the pump head cover is rotatably supported on the pump head cover via a first bearing. Thus, the space in the pump head cover may be utilized to mount the first bearing, thereby reducing the axial dimension of the main body.

[0009] According to another preferred embodiment of the present invention, the pump head cover may include an outer cylindrical portion and an inner cylindrical portion formed around the axial direction, the outer cylindrical portion being located radially outward from the inner cylindrical portion and including a radially outer surface for assembly to an external component, the first end being supported radially inward from the inner cylindrical portion, and the inner cylindrical portion may not extend axially away from the rotor beyond the outer cylindrical portion. The axial dimension of the pump head cover is thus determined by the assembly requirements of the radially outer surface, and only the original axial dimension of the pump head cover is utilized to meet the installation space of the first bearing. The axial dimension of the pump head cover does not need to be increased while reducing the axial dimension of the main body.

[0010] According to another preferred embodiment of the present invention, the motor shaft may further include a second end axially opposite the first end, and the electric oil pump may further include a second bearing. The second end extends axially away from the pump rotor assembly and is rotatably supported on the housing via the second bearing. The motor shaft is thus supported on the housing at both axial ends, with a larger distance between the two support points, thereby providing more stable support for the motor shaft.

[0011] According to another preferred embodiment of the present invention, the first bearing and / or the second bearing may be a sliding bearing. Sliding bearings are simpler in structure and smaller in size than ball bearings, thereby saving installation space. Sliding bearings are also less expensive and easier to install than ball bearings.

[0012] According to another preferred embodiment of the present invention, the first bearing and / or the second bearing can be fixed to the housing by interference fit, thereby enabling the bearing to have a simple structure and installation method.

[0013] According to another preferred embodiment of the present invention, the first bearing and / or the second bearing can be connected to the housing in a rotationally fixed manner by a tooth fit, which enables the bearing to be fixed more stably in the circumferential direction relative to the housing.

[0014] According to another preferred embodiment of the present invention, the inner surface of the housing can serve as the first and / or second bearings to directly support the motor shaft. In other words, the motor shaft can be supported directly by the inner surface of the housing, thereby eliminating the need for separate bearing components and reducing production and installation costs.

[0015] According to another preferred embodiment of the present invention, the radial inner surface of the first bearing and / or the second bearing for sliding contact with the motor shaft may include a lubrication groove. The lubrication groove may contain a working fluid to lubricate and cool the contact surface between the sliding bearing and the motor shaft, thereby reducing wear. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described below with reference to the accompanying drawings. Elements with the same function are represented by the same reference numerals in the drawings.

[0017] FIG1 shows a perspective cross-sectional view of an electric oil pump according to an exemplary embodiment of the present invention;

[0018] FIG2 shows a detail of the section shown in FIG1 in the region of the first end of the motor shaft;

[0019] 3 is a cross-sectional view illustrating a support structure of a motor shaft of an electric oil pump according to an exemplary embodiment of the present invention;

[0020] FIG4 shows a schematic diagram of a bearing of an electric oil pump according to an exemplary embodiment of the present invention; and

[0021] FIG5 is a schematic diagram illustrating a bearing of an electric oil pump according to another exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following detailed description and accompanying drawings are used to illustrate the principles of the present invention. The present invention is not limited to the preferred embodiments described. The scope of protection of the present invention is defined by the claims.

[0023] According to an embodiment of the present invention, an electric oil pump for driving a working fluid and generating fluid pressure is provided. Figures 1 to 4 illustrate an exemplary embodiment of the electric oil pump according to the present invention. The specific structure of the electric oil pump will be described below with reference to the accompanying drawings.

[0024] Figure 1 shows a perspective cross-sectional view of an electric oil pump according to an exemplary embodiment. As shown in Figure 1 , the electric oil pump mainly includes a drive motor 10, a pump rotor assembly 20, and a housing 30. The drive motor 10 and the pump rotor assembly 20 are installed 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, while the rotor 12 is coaxially mounted radially inwardly of 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 connected to the rotor 12 in a torque-proof manner, specifically fixed radially inwardly of the rotor 12, thereby being rotatable relative to the stator 11 and the housing 30 along the common central axis. The motor shaft 13 includes two axially opposing ends, namely a first end 13a and a second end 13b. These ends of the motor shaft 13 protrude axially beyond the rotor 12 to be supported by 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 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 axially passes through the rotor 12 and the pump rotor assembly 20, with a first end 13a of the motor shaft 13 axially extending out of the pump rotor assembly 20 away from the rotor 12, while a second end 13b extends out of the rotor 12 axially away from the pump rotor assembly 20. 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.

[0027] The motor shaft 13, which passes through the pump rotor assembly 20, is in driving connection with 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 pumping suction. The pump rotor assembly 20 can be any pump device known in the art, such as a gear pump. The specific structure and operating principle of generating pumping suction are widely known and will not be detailed here, as they do not constitute limitations of the present invention.

[0028] FIG2 illustrates a detail of the cross section shown in FIG1 in the region of first end 13a of motor shaft 13. As shown in FIG2 , the electric oil pump further includes a first bearing 40. First end 13a of motor shaft 13, which extends outside pump rotor assembly 20, is rotatably supported on housing 30 via first bearing 40. Compared to the prior art, the position of first bearing 40 has been relocated from between rotor 12 and pump rotor assembly 20 to the outside of pump rotor assembly 20.

[0029] Specifically, the housing 30 may include a main body 31, a pump head cover 32 and a controller cover 33. The main body 31 is roughly cylindrical around the central axis. The motor cavity and the pump rotor cavity are basically formed in the main body 31. As shown in Figure 1, the motor cavity and the pump rotor cavity are axially separated by a partition wall formed inside the main body 31. The motor cavity is open axially away from the pump rotor assembly 20, and the controller cover 33 is fixed to the main body 31 at the open end of the motor cavity, thereby closing the motor cavity. The pump rotor cavity is open axially away from the rotor 12, and the pump head cover 32 is fixed to the main body 31 at the open end of the pump rotor cavity, thereby closing the pump rotor cavity. At the same time, the pump head cover 32 is arranged axially adjacent to the pump rotor assembly 20, so that the pump head cover 32 and the partition plate axially constrain the pump rotor assembly 20, so that the pump rotor assembly 20 basically cannot move axially relative to the housing 30.

[0030] Here, the first end 13a can be supported on the pump head cover 32 by the first bearing 40. Specifically, as shown in Figure 2, the pump head cover 32 may include an outer cylinder portion 32a and an inner cylinder portion 32b formed around the axial direction. The outer cylinder portion 32a is located radially outside the inner cylinder portion 32b. The space between the outer cylinder portion 32a and the inner cylinder portion 32b can constitute the high-pressure chamber and the low-pressure chamber of the pump rotor assembly 20. The radial outer surface of the outer cylinder portion 32a can be used to assemble to external components (such as components that require pump suction provided by an electric oil pump). The inner cylinder portion 32b is open toward one end of the pump rotor assembly 20 and closed at the other end facing away from the pump rotor assembly 20. The first end 13a is inserted into the inner cylinder portion 32b from the open end of the inner cylinder portion 32b and is supported on the radial inside of the inner cylinder portion 32b by the first bearing 40. Due to the assembly requirements of the radially outer surface of the outer cylindrical portion 32a, the outer cylindrical portion 32a must have a certain axial length. Therefore, the axial dimension of the pump head cover 23 must not be less than the axial length of the outer cylindrical portion 32a. Therefore, this dimension can be used to provide space for the first bearing 40, thereby avoiding occupying space within the main body 31. Preferably, the inner cylindrical portion 32b does not extend axially away from the outer cylindrical portion 32a, so that the overall axial dimension of the pump head cover 23 is determined solely by the outer cylindrical portion 32a.

[0031] The first bearing 40 can be various types of bearings, preferably a sliding bearing. The first bearing 40 as a sliding bearing can be fixed to the inner cylinder portion 32b and slide in contact with the first end 13a of the motor shaft 13. For example, Figure 4 shows an exemplary structure of the first bearing 40, wherein the first bearing 40 has a smooth radial outer surface and can be fixed to the inner cylinder portion 32b of the pump head cover 32 by an interference fit. For another example, Figure 5 shows another exemplary structure of the first bearing 40, wherein the first bearing 40 is formed with teeth on the radial outer surface, and correspondingly, teeth are also formed on the radial inner surface of the inner cylinder portion 32b, and the first bearing 40 can be connected to the inner cylinder portion 32b in a torsion-resistant manner by tooth fit.

[0032] Furthermore, as shown in FIG5 , the radial inner surface of the first bearing 40 that slides into contact with the motor shaft 13 may further include one or more lubrication grooves 41 . Each lubrication groove 41 is substantially radially recessed relative to the radial inner surface of the first bearing 40 . Each lubrication groove 41 may also substantially axially extend through the first bearing 40 . When multiple lubrication grooves 41 are present, they may be spaced apart circumferentially, and in particular, evenly spaced apart. Working fluid may enter and be stored in the lubrication grooves 41 , thereby being distributed to the contact surface when the motor shaft 13 rotates relative to the first bearing 40 , thereby reducing wear and heat generation.

[0033] In the embodiments shown in Figures 4 and 5 , the first bearing 40 is assembled to the housing 30 as a separate component. In alternative embodiments, the inner surface of the housing 30 can also serve as the first bearing 40, directly slidably supporting the first end 13a of the motor shaft 13. In other words, there is no need to install a separate bearing. This reduces the number of components and the number of additional assembly steps.

[0034] Preferably, the electric oil pump may further include a second bearing 50. The second end 13b of the motor shaft 13 may be rotatably supported on the housing 30 via the second bearing 50. For example, the second end 13b may be supported on the controller cover 33 via the second bearing 50. Figure 3 shows a cross-sectional view of the support structure of the motor shaft 13 in this embodiment. As shown in Figure 3, the motor shaft 13 is now supported on the housing 30 at both axial ends via two bearings. This increases the axial distance between the two support points of the motor shaft 13, thereby achieving greater support stability.

[0035] Similar to the first bearing 40, the second bearing 50 may also preferably be a sliding bearing. The second bearing 50 as a sliding bearing can be fixed to the controller cover 33 and slide in contact with the second end 13b of the motor shaft 13. The second bearing 50 may also adopt the structure shown in Figure 4 and be fixed to the controller cover 33 by an interference fit. Alternatively, the second bearing 50 may also adopt the structure shown in Figure 5 and be torsionally connected to the controller cover 33 by a tooth fit. Similarly, the radial inner surface of the second bearing 50 for sliding contact with the motor shaft 13 may also include one or more lubrication grooves 51, each lubrication groove 41 being substantially radially recessed relative to the radial inner surface of the first bearing 40. Alternatively, the inner surface of the housing 30 may also serve as the second bearing 50 to directly slide and support the second end 13b of the motor shaft 13, thereby eliminating the need for an independent second bearing.

[0036] In the electric oil pump according to the present invention, the installation position of the bearing close to the pump rotor assembly is changed. The motor shaft extends out of the pump rotor assembly, and the end of the motor shaft is supported on the housing by a first bearing. This allows the axial spacing between the rotor of the drive motor and the pump rotor assembly to be reduced. At the same time, the space provided by the necessary axial dimensions for assembly on the pump head cover can be used to accommodate the first bearing, so no additional axial dimensions are required. This significantly reduces the axial dimensions of the entire electric oil pump and makes the overall layout more compact. At the same time, the two support points of the motor shaft are located at the axial ends of the motor shaft, which increases the spacing between the support points and improves the support stability. A sliding bearing with a simple structure and low cost can be used to support the motor shaft, thereby effectively saving production costs. In addition, since the first bearing is located on the outside of the pump rotor assembly, the pump rotor assembly can be installed first during assembly, and then the first bearing can be installed, making the assembly process simpler and the bearing less likely to be damaged during assembly.

[0037] While the foregoing descriptions illustrate possible embodiments, it should be understood that numerous variations exist through combinations of all known and other technical features and implementations readily conceivable to a skilled artisan. Furthermore, it should be understood that the exemplary embodiments serve merely as examples and in no way limit the scope, application, or configuration of the present invention. The foregoing descriptions are intended primarily to provide a skilled artisan with technical guidance for implementing at least one exemplary embodiment. Various modifications, particularly regarding the functionality and structure of the components described, may be made without departing from the scope of the claims.

[0038] REFERENCE NUMERALS 10 Drive motor 11 Stator 12 Rotor 13 Motor shaft 13a First end 13b Second end 20 Pump rotor assembly 30 Housing 31 Main body 32 Pump head cover 32a Outer cylinder 32b Inner cylinder 33 Controller cover 40 First bearing 41 Lubrication groove 50 Second bearing 51 Lubrication groove

Claims

1. An electric oil pump, comprising a drive motor (10), a pump rotor assembly (20) and a housing (30), wherein the drive motor (10) and the pump rotor assembly (20) are mounted in the housing (30), the drive motor (10) comprising a rotor (12) and a motor shaft (13) coaxially connected in a torsionally fixed manner, the rotor (12) and the pump rotor assembly (20) being spaced apart in the axial direction, and the motor shaft (13) passing through the rotor (12) and the pump rotor assembly (20) in sequence in the axial direction, It is characterized in that The electric oil pump further includes a first bearing (40), the motor shaft (13) includes a first end (13a) extending axially away from the rotor (12) from the pump rotor assembly (20), and the first end (13a) is rotatably supported on the housing (30) via the first bearing (40).

2. The electric oil pump according to claim 1, characterized in that The housing (30) includes a main body (31) and a pump head cover (32), the main body (31) including a pump rotor cavity that is open axially away from the rotor (12) and accommodates the pump rotor assembly (20), the pump head cover (32) is fixed to the main body (31) adjacent to the pump rotor assembly (20) in the axial direction to close the pump rotor cavity, and the first end (13a) is rotatably supported on the pump head cover (32) via the first bearing (40).

3. The electric oil pump according to claim 2, the pump head cover (32) includes an outer cylinder portion (32a) and an inner cylinder portion (32b) formed around the axial direction, the outer cylinder portion (32a) is located radially outside the inner cylinder portion (32b) and includes a radial outer surface for assembly to an external component, the first end (13a) is supported on the radial inside of the inner cylinder portion (32b), and the inner cylinder portion (32b) does not extend out of the outer cylinder portion (32a) axially away from the rotor (12).

4. The electric oil pump according to any one of claims 1 to 3, characterized in that: The motor shaft (13) further includes a second end (13b) axially opposite to the first end (13a), and the electric oil pump further includes a second bearing (50), wherein the second end (13b) extends out of the rotor (12) axially away from the pump rotor assembly (20) and is rotatably supported on the housing (30) via the second bearing (50).

5. The electric oil pump according to claim 4, characterized in that: The first bearing (40) and / or the second bearing (50) are sliding bearings.

6. The electric oil pump according to claim 5, characterized in that The first bearing (40) and / or the second bearing (50) are fixed to the housing (30) by interference fit.

7. The electric oil pump according to claim 5, characterized in that The first bearing (40) and / or the second bearing (50) are connected to the housing (30) in a rotationally fixed manner via a tooth fit.

8. The electric oil pump according to claim 5, characterized in that The inner surface of the housing (30) serves as the first bearing (40) and / or the second bearing (50) to directly slide and support the motor shaft (13).

9. The electric oil pump according to claim 5, characterized in that: The radial inner surface of the first bearing (40) and / or the second bearing (50) for sliding contact with the motor shaft (13) comprises a lubrication groove (41, 51).

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