A bearing for a fluid pump

Abstract

The present invention provides a bearing for a fluid pump. When the fluid pump is working, a positive pressure area (28) for fluid to be pumped out and a negative pressure area (27) for fluid to flow in are formed in the fluid pump. A lubrication groove (261) extending in the axial direction is formed on the wall of the shaft hole (26) of the bearing (25). The lubrication groove (261) is connected to the positive pressure area (28) and is in the shape of a blind groove. The present invention can reduce the clamping force of the oil seal and reduce the manufacturing cost of the fluid pump.

Description

Technical Field

[0001] The present invention relates to a fluid pump, in particular to a bearing used for a fluid pump. Background Art

[0002] When a fluid pump, such as an oil pump, is working, the rotor inside the oil pump rotates at high speed. In order to reduce the friction between the rotating shaft and the wall of the shaft hole of the pump body, that is, the sliding bearing, the contact part must be lubricated.

[0003] Chinese Patent Application Publication CN105298837A discloses a technical solution for lubricating a sliding bearing, which achieves lubrication of the sliding bearing by forming an oil passage.

[0004] However, although the above technical solution realizes the lubrication of the sliding bearing with a relatively simple structure and relatively low cost, in order to prevent the lubricating oil from flowing out of the pump along the motor shaft, a sealing component needs to be provided between the pump housing and the motor shaft, and in order to ensure good sealing performance, a certain clamping force is required between the motor shaft and the sealing component. On the one hand, this increases the starting torque of the oil pump, resulting in an increase in the failure rate of starting, an increase in the loss of the oil pump, and a decrease in efficiency; on the other hand, the sealing component must be made of a more wear-resistant material, resulting in an increase in the cost of raw materials. The above problems will eventually reduce the market competitiveness of the product. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a bearing for a fluid pump, which can achieve good lubrication and prevent excessive oil from flowing to the oil seal, thereby reducing the clamping force of the oil seal and ultimately reducing the friction torque.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a bearing for a fluid pump. When the fluid pump is working, a positive pressure area for fluid to be pumped out and a negative pressure area for fluid to flow in are formed in the fluid pump.

[0007] A lubrication groove extending in the axial direction is formed on the wall of the shaft hole of the bearing. The lubrication groove is communicated with the positive pressure area and is in a blind groove shape.

[0008] In one embodiment of the present invention, the lubrication groove is disposed in a negative pressure area where a lubrication film is formed in the shaft hole when the fluid pump is working.

[0009] In one embodiment of the present invention, in the axial direction, a ratio of the length of the lubrication groove to the length of the shaft hole is greater than or equal to 0.5 and less than or equal to 0.95.

[0010] In one embodiment of the present invention, a lubrication groove is provided on each side of the main load to which the fluid pump is subjected during operation.

[0011] In one embodiment of the present invention, when the fluid pump is working, the shaft driving the fluid pump rotates in the shaft hole. In the rotation direction of the shaft, one of the lubrication grooves is located in the area on the positive pressure area side away from the lubrication film, and the other lubrication groove is located in the area on the positive pressure area side entering the lubrication film.

[0012] In one embodiment of the present invention, the angle between the two lubrication grooves is greater than or equal to 30° and less than or equal to 180°.

[0013] In one embodiment of the present invention, the lubricating groove is disposed at a location where the lubricating film has a maximum film thickness.

[0014] As described above, the bearing of the present invention reduces the oil accumulation at the oil seal and can reduce the clamping force of the oil seal, thereby achieving the effect of reducing the friction torque when the fluid pump rotates and improving the success rate of starting the fluid pump, thereby improving the reliability of the product and reducing the wear of the oil seal lip and the rotating shaft.

[0015] The reduction of sealing oil pressure can reduce the holding force of the oil seal, so that a low-grade oil seal can be used. The lower the grade of the oil seal, the lower the price. Choosing a low-grade oil seal can reduce the overall manufacturing cost of the fluid pump. At the same time, the motor shaft and oil seal can use cheap raw materials to reduce the cost of raw materials, especially when produced in large quantities, the cost reduction is more obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. 1 is an exploded view of a fluid pump according to an embodiment of the present invention.

[0017] Figure 2 Shown is a front view of a pump body according to an embodiment of the present invention.

[0018] Figure 3 Display as Figure 2 AA section view of the pump body.

[0019] Figure 4 Shown is a diagram of the working principle of a trochoid pump.

[0020] Figure 5 A schematic diagram showing the dynamic pressure lubrication in the shaft hole of the bearing of the present invention. DETAILED DESCRIPTION

[0021] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0022] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0023] In this embodiment, the fluid pump takes the electric oil pump 100 as an example. Figure 1 , Figure 1 An exploded view of an electric oil pump 100 according to the present invention is shown.

[0024] Figure 1 is an exploded view of the electric oil pump 100. Figure 1 As shown, the electric oil pump 100 is provided with a base 1, a pump body 2, a motor 3 providing driving force and a rear cover 4 from bottom to top, and the base 1, the pump body 2, the motor 3 providing driving force and the rear cover 4 are fixedly connected in sequence by fasteners, and the fasteners can be screws, bolts or pins. The bottom of the base 1 is connected to the gearbox or the engine ( Figure 1 The base 1 is connected to an application object (not shown), and an oil inlet hole 11 and an oil outlet hole 12 are formed through the upper and lower end surfaces of the base 1.

[0025] Figure 2 A front view of the pump body in one embodiment is given. Figure 3 Given Figure 2 AA section view. For ease of viewing, the section is not hatched.

[0026] like Figure 3 As shown, the bearing 25 is integrally formed on a pump body 2, and the pump body 2 also has a pump body 24, and a chamber 23 is formed on the axial wall surface of one side of the pump body 24. The chamber 23 is equipped with an outer rotor 21 and an inner rotor 22 meshing with the outer rotor 21 to form a cycloid pump. When the electric oil pump 100 is working, a positive pressure area 28 for pumping out the fluid and a negative pressure area 27 for the fluid to flow in are formed. In the embodiment, the positive pressure area 28 and the negative pressure area 27 are formed on the axial end surface 231 of the chamber 23. The inner rotor 22 and the outer rotor 21 rotate in the chamber 23 to suck and pump out the oil. A through hole 20 for fixing the pump body is opened in the circumferential direction of the pump body 24, and the pump body 2 is connected to the base 1 and the motor 3 respectively by fasteners.

[0027] It should be noted that Figure 1 The electric oil pump 100 in the embodiment is a cycloid pump. The working principle of the cycloid pump is as follows: Figure 4 As shown, the inner rotor 22 and the outer rotor 21 are internally meshed, and the inner rotor 22 has 6 external teeth. Correspondingly, the outer rotor 21 has 7 internal teeth. The inner rotor 22 rotates clockwise in the direction shown in the figure, and each external tooth of the inner rotor 22 meshes with a different part of the internal tooth of the outer rotor 21. The 7 inter-tooth spaces formed between the inner rotor 22 and the outer rotor 21 are Figure 4 The middle teeth 224 and teeth 225, teeth 225 and teeth 226, teeth 226 and teeth 221 respectively form three inter-tooth spaces with the outer rotor 21, and the volume of each inter-tooth space changes from large to small. The left side of the inner rotor 22 forms an oil pressure chamber 281, an oil pressure chamber 282 and an oil pressure chamber 283, respectively. The oil pressure chamber 281, the oil pressure chamber 282 and the oil pressure chamber 283 are respectively connected to the positive pressure area 28 on the pump body 2; the teeth 221 and teeth 222, the teeth 222 and teeth 223, and the teeth 223 and teeth 224 respectively form three inter-tooth spaces with the outer rotor 21, and the volume of each inter-tooth space changes from small to large. The right side of the inner rotor 22 forms an oil suction chamber 271, an oil suction chamber 272 and an oil suction chamber 273, respectively. The oil suction chamber 272 and the oil suction chamber 273 are connected to the negative pressure area 27 on the pump body 2. Among them, the negative pressure area 27 is connected to the oil suction chamber 271, the oil suction chamber 272 and the oil suction chamber 273, and the positive pressure area 28 is connected to the oil pressure chamber 281, the oil pressure chamber 282 and the oil pressure chamber 283. As the inner rotor 22 rotates in the direction shown in the figure, the oil in the oil suction chamber 273, the oil suction chamber 272 and the oil suction chamber 271 is sequentially sent from the negative pressure area 27 to the positive pressure area 28.

[0028] like Figure 2-Figure 3 As shown, the bearing 25 has an axial hole 26 passing through it, one side of the axial hole 26 is connected to the chamber 23, the motor shaft 33 is inserted into the axial hole 26 and connected to the inner rotor 22, the motor shaft 33 is sleeved on the outside of the motor shaft 33, when the motor 3 is started, the motor shaft 33 drives the inner rotor 22 to rotate, and the bearing 25 of the pump body 2 constitutes a sliding bearing of the motor shaft 33.

[0029] In order to lubricate the motor shaft 33 and the wall of the shaft hole 26, a lubrication groove 261 is axially provided along the wall of the shaft hole 26. The lubrication groove 261 is in the shape of a blind groove. The lubrication groove 261 is connected to the positive pressure zone 28 through an oil supply passage 263. The oil supply passage 263 is provided on the axial end face of the chamber 23. Figure 2A pair of lubrication grooves 261 symmetrically arranged in the circumferential direction is given, but this does not mean that two lubrication grooves 261 must be provided. The number of lubrication grooves 261 can be arbitrary, and the shape and relative position relationship of each lubrication groove 261 are not particularly limited. The lubrication groove 261 can be integrally formed with the pump body 2, or can be formed by cutting. Among them, the negative pressure area 27 connects the oil suction chamber 271, the oil suction chamber 272 and the oil suction chamber 273, and the positive pressure area 28 connects the oil pressure chamber 281, the oil pressure chamber 282 and the oil pressure chamber 283. The oil pressure in the positive pressure area 28 is significantly greater than the oil pressure in the negative pressure area 27.

[0030] It should be noted that Figure 2 The position of the lubrication groove 261 shown in the figure can be set according to the direction of the main load on the motor shaft 33, wherein the main load can be the rotating part of the electric oil pump 100, such as the gravity of the inner rotor 22, the motor shaft 33, the motor rotor and the magnet, the radial thrust of the oil pressure on the inner rotor 22, etc. When setting the position of the lubrication groove 261, first determine the main load direction of the electric oil pump 100 and the positive pressure area and negative pressure area where the lubricating oil film is formed in the shaft hole 26. In this embodiment, Figure 2 The main load is generally directed from the positive pressure area 28 to the negative pressure area 27, such as Figure 5 FIG. 3 is a schematic diagram showing the dynamic pressure lubrication in the shaft hole 26 of the motor shaft 33 after the motor shaft 33 is subjected to the main load. Figure 5 The main load is the main load F, and the motor shaft 33 rotates as shown in the figure. Figure 5 , according to the principle of fluid dynamic lubrication, Figure 5 The shaded portion is the load-bearing area of ​​the lubricating oil film, which is the positive pressure area of ​​the oil film, and the other portions except the load-bearing area are the negative pressure areas of the oil film.

[0031] In order to ensure the stability of the oil film in the shaft hole 26, Figure 5 The region E and region D where the lubrication grooves can be set are shown in FIG. In this embodiment, a plurality of lubrication grooves 261 can be provided along the axial direction of the hole wall of the shaft hole 26. Preferably, the lubrication grooves are provided near the maximum thickness of the lubrication film, that is, near the maximum gap between the shaft and the shaft hole. The position of the lubrication grooves 261 in the circumferential direction can be designed and adjusted according to the oil pressure of the lubricating oil in the positive pressure area 28.

[0032] In addition, if the axial length of the lubrication groove 261 is too short, a part of the shaft will not be fully lubricated, and if it is too long, it will easily increase the leakage of oil along the axial direction, which is not only not conducive to the lubrication of the shaft, but also reduces the overall efficiency of the oil pump. In the axial direction, the ratio of the length of the lubrication groove 261 to the length of the shaft hole 26 is greater than or equal to 0.5 and less than or equal to 0.95, preferably greater than or equal to 0.6 and less than or equal to 0.9.

[0033] Combination Figure 2 and Figure 5 As shown, a lubrication groove 261 is provided on each side of the main load F to which the electric oil pump 100 is subjected when working. When the fluid pump is working, the motor shaft 33 driving the electric oil pump 100 rotates in the shaft hole. In the rotation direction of the shaft, one of the lubrication grooves 261 is located in the area D on the side of the positive pressure area leaving the lubrication film, and the other lubrication groove 261 is located in the area E on the side of the positive pressure area entering the lubrication film. The angle α between the two lubrication grooves 261 is greater than or equal to 30° and less than or equal to 180°, so as to ensure that a complete lubrication film can be formed in the shaft hole 26.

[0034] In addition, in this embodiment, when the number of lubrication grooves 261 reaches more than 2, an oil accumulation groove 262 is also formed on the axial end face of the chamber. The oil accumulation groove 262 connects all the lubrication grooves 261, and the oil accumulation groove 262 is also connected to the oil supply path 263. The purpose of setting the oil accumulation groove 262 is to accumulate the oil from the positive pressure zone 28 in the oil accumulation groove 262, so that oil can be stably supplied to each lubrication groove. The oil accumulation groove 262 can be formed around the shaft hole 26, and can be in an annular, semi-annular or other shape, which is not limited here.

[0035] exist Figure 3 In the figure, the motor shaft 33 rotates in the shaft hole 26, and there is a gap between the motor shaft 33 and the wall of the shaft hole 26. The inner rotor 22 and the outer rotor 21 suck the oil into the negative pressure area 27 through the oil inlet hole 11. During the rotation of the inner rotor 22 and the outer rotor 21, the oil is pumped into the positive pressure area 28, and at the same time enters between the motor shaft 33 and the wall of the shaft hole 26 through the lubrication groove 261. As the motor shaft 33 rotates, an oil film is generated, which wraps the motor shaft 33, and plays a role in lubricating and radially supporting the motor shaft 33.

[0036] In addition, since the lubrication groove 261 is in the form of a blind groove (such as Figure 3 As shown in FIG. 2 , the closed end of the lubricating groove 261 intercepts the oil flowing into the lubricating groove 261, so that although the oil cannot be completely prevented from flowing out, only a very small amount of oil can flow over the closed end to the oil seal 5, which greatly reduces the oil pressure on the oil seal 5 as a sealing member. In addition, compared with the lubricating groove that is completely axially through, in the present invention, most of the oil is intercepted by the closed end of the lubricating groove 261, so the oil lubricating between the motor shaft 33 and the shaft hole 26 is reduced, thereby reducing the oil pump loss and improving the efficiency.

[0037] In this embodiment, a groove 29 (such as a groove 29 for accommodating the oil seal 5) is provided at the end of the bearing 25 away from the positive pressure area 28 and the negative pressure area 27. Figure 3As shown), the groove 29 is connected to the shaft hole 26, and the groove 29 is not connected to the lubrication groove 261. During assembly, the oil seal 5 is sleeved on the motor shaft 33, and there is a certain clamping force between the oil seal 5 and the motor shaft 33. It should be noted that since the lubrication groove 261 is not directly connected to the groove 29 where the oil seal 5 is located, and since the lubrication groove 261 is in the shape of a blind groove, it is not easy for oil to accumulate at the oil seal 5 in this embodiment. Therefore, since the oil pressure to be blocked is reduced, the clamping force of the oil seal 5 can be reduced during design, thereby achieving the purpose of reducing the friction torque when the electric oil pump 100 rotates and increasing the success rate of starting the electric oil pump 100. The reliability of the product is improved, and the wear of the lip of the oil seal 5 and the shaft is reduced. At the same time, reducing the clamping force of the oil seal 5 can greatly reduce the material grade of the oil seal 5. Since the lower the material grade of the oil seal 5, the lower the price, selecting an oil seal 5 made of low-grade material can reduce the overall manufacturing cost of the electric oil pump 100. At the same time, the motor shaft 33 can also use cheap raw materials to reduce the cost of raw materials, especially when produced in large quantities, the cost reduction is more obvious.

[0038] It should be noted that, in actual use, the oil entering the lubrication groove 261 can be replaced by other liquids or gases, such as water or air.

[0039] Next, the pumping action of the electric oil pump 100 configured as described above will be described.

[0040] Electric oil pump 100 Figure 1 As shown in the figure, the motor 3 is started at first during operation.

[0041] like Figure 1 As shown, the oil in the gearbox is sucked into the base 1 from the oil inlet hole 11 and pumped out from the oil outlet hole 12. During the rotation of the rotor 2, part of the oil in the oil outlet hole 12 is pumped into the positive pressure area 28 through the volume change between the cycloid rotors. Figure 2 As shown, the oil flows into the lubrication groove 261. During the rotation of the motor shaft 33, the oil in the lubrication groove 261 is brought into the friction surface between the motor shaft 33 and the axial hole 26 in the pump body 2. As the motor shaft 33 rotates, an oil film is generated, which lubricates and radially supports the motor shaft 33.

[0042] in accordance with Figure 3 As shown, the oil flowing into the lubrication groove 261 is intercepted at the closed end of the lubrication groove 261 during the axial flow along the motor shaft 33, so that the amount of oil that can flow to the oil seal is very small, which can reduce the oil pressure on the oil seal, thereby limiting the oil flow to the oil seal 5 to the greatest extent, greatly reducing the clamping force and material grade of the oil seal 5. Therefore, the motor shaft 33 and the oil seal 5 can use cheap raw materials, reducing the cost of raw materials and reducing the manufacturing cost of the electric oil pump 100.

[0043] Although the above description is made by taking the electric oil pump 100 as an example, a person skilled in the art should understand that the present invention is not limited to the electric oil pump 100, and may also be any fluid pump such as a water pump, an air pump, etc. In addition, although the present invention is described by taking the cycloid pump as an example, a person skilled in the art should understand that the present invention is not limited to the cycloid pump, and may also be any pump such as a vane pump, a plunger pump, other gear pumps, etc., as long as a positive pressure area for the fluid to be pumped out and a negative pressure area for the fluid to flow in are formed in the fluid pump when the fluid pump is working. In addition, the bearing may also be separate from the pump body and fixed to the pump body by installation.

[0044] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0045] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A bearing for a fluid pump, wherein when the fluid pump is in operation, a positive pressure area (28) for fluid to be pumped out and a negative pressure area (27) for fluid to flow in are formed in the fluid pump, characterized in that: A lubrication groove (261) extending in the axial direction is formed on the wall of the shaft hole (26) of the bearing (25), and the lubrication groove (261) is in the shape of a blind groove having an open end and a blocked end, and the open end is in communication with the positive pressure zone (28); The lubrication groove (261) is provided in a negative pressure area where a lubrication film is formed in the shaft hole (26) when the fluid pump is working; When the motor shaft (33) is working, a force is applied in the radial direction eccentrically to a hole wall on one side of the shaft hole (26), and the area inside the shaft hole (26) at the hole wall on the one side is a positive pressure area of ​​the lubricating film, and the area outside the positive pressure area of ​​the lubricating film inside the shaft hole (26) is a negative pressure area of ​​the lubricating film; After the fluid is sucked into the negative pressure area (27) and pumped into the positive pressure area (28), a portion of the fluid enters the gap between the motor shaft (33) and the shaft hole (26) through the lubrication groove (261), and forms a lubrication film around the motor shaft (33) as the motor shaft (33) rotates.

2. The bearing for a fluid pump according to claim 1, characterized in that: In the axial direction, the ratio of the length of the lubrication groove (261) to the length of the shaft hole (26) is greater than or equal to 0.5 and less than or equal to 0.

95.

3. The bearing for a fluid pump according to claim 1, characterized in that: A lubrication groove (261) is provided on each side of the main load (F) to which the fluid pump is subjected when working.

4. The bearing for a fluid pump according to claim 3, characterized in that: When the fluid pump is working, the shaft driving the fluid pump rotates in the shaft hole (26). In the rotation direction of the shaft, one of the lubrication grooves (261) is located in the area (D) on the side of the positive pressure area away from the lubrication film, and the other lubrication groove (261) is located in the area (E) on the side of the positive pressure area entering the lubrication film.

5. The bearing for a fluid pump according to claim 4, characterized in that: The included angle (α) between the two lubrication grooves (261) is greater than or equal to 30° and less than or equal to 180°.

6. The bearing for a fluid pump according to claim 1, characterized in that: The lubrication groove (261) is arranged at a location where the thickness of the lubrication film is the largest.

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