An electronic oil pump for pre-tightening the steel belt of a CVT transmission

Abstract

An electronic oil pump for pre-tightening a steel belt of a CVT transmission includes a motor, a pump body, a pump cover, an outer rotor, an inner rotor and a positioning shaft, wherein the outer rotor is installed in the rotor cavity of the pump body, the inner rotor is meshed with the outer rotor, the inner rotor shaft hole is composed of a positioning shaft hole and a transmission shaft hole, the output shaft of the motor is connected to the transmission shaft hole, a bushing is installed in the positioning shaft hole, one end of the positioning shaft is installed in the bushing with a clearance, and the other end is installed in the pump body shaft hole with a clearance. The above technical solution can reduce the internal clearance of the oil pump, improve the pressure bearing capacity of the oil pump, reduce the radial force of the inner rotor that the motor output shaft needs to bear, so that the electronic oil pump can be used for pre-tightening the steel belt of the CVT transmission, directly participate in the operation of the transmission hydraulic system, shorten the transmission response time, improve the transmission efficiency of the transmission, and thus reduce the power loss of the engine.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission electronic oil pumps, and in particular to an electronic oil pump used for pre-tightening a CVT transmission steel belt. Background Art

[0002] Judging from global energy development trends and international internal combustion engine technology, controlling internal combustion engine fuel consumption and carbon dioxide and other pollutant emissions is becoming the most effective way to address global environmental protection and energy shortages. Currently, "energy-saving and new energy vehicles" are listed as key development areas in China's manufacturing industry, and national energy conservation and emission reduction policies are gradually requiring passenger vehicles to reduce fuel consumption indicators.

[0003] To meet increasingly stringent emission standards, the transmission industry has transitioned from traditional large-displacement mechanical oil pumps to a combination of a small-displacement mechanical oil pump and an electronic oil pump. When the engine is running (with the automatic start-stop function disabled), the mechanical oil pump provides the system with hydraulic oil and cooling lubricant. During this period, if the mechanical oil pump's oil supply capacity is insufficient, the electronic oil pump can supplement the oil as needed. When the engine is not running (with the automatic start-stop function enabled), the electronic oil pump provides the entire cooling lubricant supply. This combination reduces the power consumption of the traditional large-displacement mechanical oil pump, while also allowing the electronic oil pump to maintain system lubrication when the automatic start-stop function is engaged. This reduces the transmission's power consumption and effectively keeps the transmission in a standby state. Once the engine is started, the transmission can more quickly respond to shift commands and lubrication and cooling needs.

[0004] Currently, the mainstream electronic oil pump uses an internal meshing rotor. Traditional electronic oil pumps typically have an internal rotor that is directly inserted into the motor's output shaft through the inner rotor's shaft hole and driven by a spline or flat tail. The spline or flat tail structure not only drives the oil pump but also positions and supports the radial load of the inner rotor. This structure requires a high degree of precision between the oil pump and the motor; otherwise, the oil pump can easily become stuck and inflexible. To achieve higher pressure, the internal clearance needs to be reduced, placing higher demands on the accuracy of the motor's output shaft and the precision of the motor-oil pump fit. In reality, the fit between the motor and the oil pump has certain form and position tolerances, resulting in low oil supply pressure in current electronic oil pumps.

[0005] On the other hand, because it is a transmission electronic oil pump, the transmission itself has a very compact structure, so the electronic oil pump needs to strictly control its size. The output shaft of the motor is often small, and the output shaft of the motor is usually supported by bearings to keep the rotor and shaft rotating. The smaller the bearing, the smaller the radial load capacity, which will further limit the development of the oil pump in the direction of high pressure. Otherwise, the high-pressure radial load will cause the bearing to fail.

[0006] Based on the above reasons, the current transmission electronic oil pump is usually used as a lubricating oil pump, and the electronic oil pump cannot participate in the operation of the transmission hydraulic system, which in turn hinders the application of the electronic oil pump in transmission hydraulics. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an electronic oil pump for pre-tightening a CVT transmission steel belt.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solution: an electronic oil pump for pre-tightening a CVT transmission steel belt, comprising a motor, a pump body, a pump cover, an outer rotor, an inner rotor and a positioning shaft, wherein the outer rotor is installed in the rotor cavity of the pump body, the inner rotor is engaged with the outer rotor, the inner rotor shaft hole consists of a positioning shaft hole and a transmission shaft hole, the output shaft of the motor is transmission-connected in the transmission shaft hole, a bushing is interference-fitted in the positioning shaft hole, one end of the positioning shaft is gap-fitted in the bushing, and the other end is interference-fitted in the pump body shaft hole.

[0009] Preferably, the inner rotor is provided with a protrusion on the end face close to the pump cover, the protrusion is installed in the shaft hole of the pump cover with a clearance, and the transmission shaft hole passes through the protrusion.

[0010] Preferably, the motor and the pump cover are respectively provided with a positioning boss and a positioning countersunk hole on the end surfaces close to each other, and the positioning boss is fitted in the positioning countersunk hole.

[0011] More preferably, the height of the positioning boss is lower than the depth of the positioning counterbore.

[0012] More preferably, a first oil groove is provided on the side wall of the positioning counterbore, and a second oil groove is provided on the end surface of the pump cover close to the motor, and the first oil groove is communicated with the second oil groove.

[0013] Preferably, the inner hole of the bushing is precision-machined and a sintered alloy layer is provided on its surface.

[0014] Preferably, the pump body shaft hole and the rotor cavity are machined in one step.

[0015] Preferably, the positioning shaft is provided with a middle through hole.

[0016] Preferably, the electronic oil pump further includes a positioning pin, and the pump body and the pump cover are respectively provided with positioning holes for installing the positioning pin on end surfaces close to each other.

[0017] The present invention divides the inner rotor shaft hole into two parts, a positioning shaft hole and a transmission shaft hole, and provides a positioning shaft. One end of the positioning shaft is fixed to the pump body and the other end is inserted into the positioning shaft hole. This can play a good positioning role for the inner rotor, ensure the radial runout of the inner rotor, and help reduce the radial clearance of the oil pump and improve the pressure bearing capacity of the oil pump. At the same time, the positioning shaft can also bear the radial force of the inner rotor, so that the output shaft of the motor only needs to bear very little or no radial force of the inner rotor, which is conducive to the development of the oil pump in the direction of high pressure. Therefore, the electronic oil pump can reduce the internal clearance of the oil pump as much as possible, greatly reducing the radial force of the inner rotor that the output shaft of the motor needs to bear. Combined with the excellent positioning performance of the positioning shaft, the electronic oil pump can provide a maximum liquid pressure far higher than that of conventional lubricating electronic oil pumps. When the automatic start-stop function of the engine is working, the electric drive oil pump can provide high-pressure oil for pre-tightening the CVT transmission steel belt and directly participate in the operation of the transmission hydraulic system. At the same time, when the engine is in standby mode, the electronic oil pump can keep the CVT transmission steel belt in a pre-tightened state. Once the engine is working, the transmission can immediately enter the working state, shortening the transmission response time, improving the transmission efficiency, and effectively reducing engine power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of an electronic oil pump according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the explosion of the electronic oil pump;

[0020] Figure 3 It is a top view of the pump cover;

[0021] Figure 4 A cross-sectional view of the inner rotor.

[0022] In the picture:

[0023] 1——Motor 1a——Location boss 2——Pump cover

[0024] 2a——First oil groove 2b——Second oil groove 2c——Positioning countersunk hole

[0025] 3——Outer rotor 4——Inner rotor 4a——Protrusion

[0026] 4b——Positioning shaft hole 4c——Transmission shaft hole 5——Bushing

[0027] 6——Location pin 7——Location shaft 7a——Middle through hole

[0028] 8——Pump body 9——Output shaft 10——Positioning hole DETAILED DESCRIPTION

[0029] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and drawings. The contents mentioned in the embodiments are not intended to limit the present invention.

[0030] It should be noted that, in the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0031] Furthermore, in the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a higher horizontal height than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or diagonally below the second feature, or may simply mean that the first feature is at a lower horizontal height than the second feature. Terms such as "above," "below," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," and "outside" to indicate positions or locations are based on the positions or locations shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention.

[0032] like Figures 1 to 4 As shown, an electronic oil pump for pre-tightening the steel belt of a CVT transmission includes a motor 1, a pump body 8, a pump cover 2, an outer rotor 3, an inner rotor 4 and a positioning shaft 7. The outer rotor 3 is installed in the rotor cavity of the pump body 8, and the inner rotor 4 is internally meshed with the outer rotor 3. The shaft hole of the inner rotor 4 consists of a positioning shaft hole 4b and a transmission shaft hole 4c. The output shaft 9 of the motor 1 is transmission-connected to the transmission shaft hole 4c. A bushing 5 is interference-fitted in the positioning shaft hole 4b. One end of the positioning shaft 7 is gap-fitted in the bushing 5, and the other end is interference-fitted in the shaft hole of the pump body 8.

[0033] The electronic oil pump for CVT transmission belt pretensioning provided in the above embodiment, by configuring the inner rotor 4 axial bore into two parts, a positioning shaft bore 4b and a drive shaft bore 4c, and providing a positioning shaft 7, with one end of the positioning shaft 7 fixed to the pump body 8 and the other end inserted into the positioning shaft bore 4b, can effectively position the inner rotor 4, ensuring radial runout of the inner rotor 4, thereby reducing the radial clearance of the oil pump and improving the oil pump's pressure-bearing capacity. At the same time, the positioning shaft 7 can also bear the radial force of the inner rotor 4, so that the output shaft 9 of the motor 1 only needs to bear little or no radial force of the inner rotor 4, which is conducive to the development of the oil pump in the direction of high pressure. Therefore, the electronic oil pump can minimize the internal clearance of the oil pump, greatly reducing the radial force of the inner rotor 4 that the output shaft 9 of the motor 1 needs to bear. Combined with the excellent positioning performance of the positioning shaft 7, the electronic oil pump can provide a maximum hydraulic pressure far higher than conventional lubrication electronic oil pumps. Moreover, when the engine automatic start-stop function is activated, the electric drive oil pump can provide high-pressure oil for CVT transmission belt pretensioning, directly participating in the operation of the transmission hydraulic system. At the same time, when the engine is in standby mode, the electronic oil pump can keep the CVT transmission steel belt in a pre-tightened state. Once the engine is working, the transmission can immediately enter the working state, shortening the transmission response time, improving the transmission efficiency, and effectively reducing engine power loss.

[0034] It should be noted that the transmission connection between the output shaft 9 of the motor 1 and the inner rotor 4 can be such that the end of the output shaft 9 is a flat tail structure, the transmission shaft hole 4c of the inner rotor 4 is a flat tail hole, and the flat tail end of the output shaft 9 is loosely mounted in the flat tail hole of the inner rotor 4. Of course, other transmission connection methods can also be used between the output shaft 9 of the motor 1 and the inner rotor 4, such as a spline connection. In the above technical solution, the diameters of the positioning shaft hole 4b and the transmission shaft hole 4c can be the same or different. In this embodiment, the diameter of the positioning shaft hole 4b is preferably larger than the diameter of the transmission shaft hole 4c.

[0035] In this embodiment, as a preferred manner, the inner rotor 4 is provided with a protrusion 4a on the end face close to the pump cover 2. The protrusion 4a is gap-mounted in the shaft hole of the pump cover 2, and the transmission shaft hole 4c passes through the protrusion 4a. By radially limiting the inner rotor 4, the radial force of the inner rotor 4 that the output shaft 9 of the motor 1 needs to bear can be further reduced, which is conducive to the development of the oil pump towards higher pressure.

[0036] Preferably, the height of the positioning boss 1a can be lower than the depth of the positioning countersunk hole 2c, so that the high-pressure oil accumulated in the motor 1 housing can partially flow into the space between the positioning boss 1a and the positioning countersunk hole 2c, thereby playing a certain pressure-reducing role.

[0037] More preferably, the side wall of the positioning countersunk hole 2c is provided with a first oil groove 2a, and the pump cover 2 is provided with a second oil groove 2b on the end face close to the motor 1, and the first oil groove 2a is connected to the second oil groove 2b. Among them, the heat dissipation of the motor 1 rotor is of immersion type, and the oil needs to enter the motor 1 housing to dissipate the heat of the motor 1 rotor and coil, and the oil leaked from the oil pump enters the motor 1 housing through the axial hole of the pump cover 2. The oil pressure in the motor 1 housing cannot be too large, otherwise it will cause the running resistance of the motor 1 to increase, affecting the normal operation of the motor 1. At the same time, if the pressure is too high, the high-pressure oil generated may also destroy the sealing between the controller and the motor 1, causing the oil to enter the controller and cause the controller to fail. The first oil groove 2a and the second oil groove 2b that are connected and provided on the pump cover 2 form an oil drain channel, which can release the high-pressure oil accumulated in the motor 1 housing, ensuring that the motor 1 housing is full of oil without forming excessive pressure.

[0038] Preferably, the inner hole of the bushing 5 is precision-machined and its surface is provided with a sintered alloy layer. The inner hole of the bushing 5 is precision-machined, which can further ensure the radial runout of the inner rotor 4, which is beneficial to reducing the radial clearance of the oil pump and improving the pressure-bearing capacity of the oil pump; and the surface of the inner hole of the bushing 5 is a sintered alloy layer, which can effectively improve the PV value of the bushing 5, thereby improving the radial bearing capacity of the bushing 5 and avoiding failure of the bushing 5 due to large radial force when the oil pump works at high pressure.

[0039] Preferably, the shaft hole of the pump body 8 and the rotor cavity are machined in one step, which can make the shaft hole of the pump body 8 and the rotor cavity have very good positioning accuracy. After the positioning shaft 7 is pressed into the shaft hole of the pump body 8, the good positioning accuracy can be maintained, so that the positioning accuracy of the inner rotor 4 and the outer rotor 3 after installation is higher, so that the radial gap between the inner rotor 4 and the outer rotor 3 can be reduced as much as possible, reducing the amount of oil leakage, thereby improving the pressure-bearing capacity of the oil pump.

[0040] Preferably, the positioning shaft 7 is provided with a middle through hole 7a, which can be used as an exhaust hole when the positioning shaft 7 is pressed, to prevent large resistance from being generated between the positioning shaft 7 and the shaft hole of the pump body 8 during the pressing process, making it easier to press the positioning shaft 7.

[0041] Preferably, the electronic oil pump also includes a locating pin 6, and the pump body 8 and the pump cover 2 are respectively provided with a locating hole 10 for installing the locating pin 6 on the end faces close to each other. This structure can ensure the accurate installation position of the pump body 8 and its components and the pump cover 2.

[0042] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has disclosed the preferred embodiments as above, it is not intended to limit the product form and style of the present invention. Any technician familiar with this profession can make some changes or modifications to the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, all contents that do not depart from the technical solution of the present invention still fall within the patent scope of the technical solution of the present invention.

Claims

1. An electronic oil pump for pre-tightening a steel belt of a CVT transmission, comprising a motor (1), a pump body (8), a pump cover (2), an outer rotor (3), and an inner rotor (4), wherein the outer rotor (3) is mounted in a rotor cavity of the pump body (8), and the inner rotor (4) is meshed with the outer rotor (3), characterized in that: The electronic oil pump further comprises a positioning shaft (7); the shaft hole of the inner rotor (4) consists of a positioning shaft hole (4b) and a transmission shaft hole (4c); the output shaft (9) of the motor (1) is transmission-connected in the transmission shaft hole (4c); a bushing (5) is interference-fitted in the positioning shaft hole (4b); one end of the positioning shaft (7) is clearance-fitted in the bushing (5) and the other end is interference-fitted in the shaft hole of the pump body (8); a protrusion (4a) is provided on the end face close to the pump cover (2); the protrusion (4a) is clearance-fitted in the shaft hole of the pump cover (2); the transmission shaft hole (4c) passes through the protrusion (4a); the motor (1) and the pump cover (2) are respectively provided with a positioning boss (1a) and a positioning countersunk hole (2c) on the end faces close to each other; the positioning boss (1a) is cooperatively fitted in the positioning countersunk hole (2c).

2. The electronic oil pump for CVT transmission steel belt pre-tightening according to claim 1, characterized in that: The height of the positioning boss (1a) is lower than the depth of the positioning counterbore (2c).

3. The electronic oil pump for CVT transmission steel belt pre-tightening according to claim 2, characterized in that: The side wall of the positioning countersunk hole (2c) is provided with a first oil groove (2a), and the pump cover (2) is provided with a second oil groove (2b) on the end surface close to the motor (1), and the first oil groove (2a) is connected to the second oil groove (2b).

4. The electronic oil pump for CVT transmission steel belt pretensioning according to claim 1, characterized in that: The inner hole of the bushing (5) is finely machined and its surface is provided with a sintered alloy layer.

5. The electronic oil pump for CVT transmission steel belt pre-tightening according to claim 1, characterized in that: The shaft hole and the rotor cavity of the pump body (8) are formed by one-step machining.

6. The electronic oil pump for CVT transmission steel belt pre-tightening according to claim 1, characterized in that: The positioning shaft (7) is provided with a middle through hole (7a).

7. The electronic oil pump for CVT transmission steel belt pre-tightening according to claim 1, characterized in that: The electronic oil pump also includes a positioning pin (6), and the pump body (8) and the pump cover (2) are respectively provided with positioning holes (10) for installing the positioning pin (6) on the end surfaces close to each other.

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