Gear shaping method, oil pump and vehicle

Abstract

The present invention discloses a gear shaping method, an oil pump, and a vehicle. The gear shaping method includes: determining a pre-shaped gear for the oil pump and shaping an external gear; determining a shaping position for the external gear and shaping each tooth of the external gear within a preset range on both axial end faces; determining a tooth shaping pattern for both axial end faces, wherein the axial width of the tooth decreases gradually from the inside to the outside along the radial direction of the external gear; and determining a tooth shaping amount F_m, which is calculated based on the tooth tip diameter da, the shaping starting circle diameter dm, and the misalignment angle β between the external gear and the shaft. The gear shaping method of an embodiment of the present invention systematically addresses the wear, efficiency degradation, and NVH issues of internal gear oil pumps caused by tilted meshing by performing axial width tapering on the tooth tips (from tooth root to tooth tip). This method converts point contact concentrated at the tooth tip during tilted meshing into contact along the modified profile.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic transmission equipment, and in particular to a gear shaping method, an oil pump and a vehicle. Background Art

[0002] In the actual operation of a vehicle's internal gear oil pump, inherent factors such as the assembly clearance between the external gear and the drive shaft, load-induced deformation of the support shaft, and bearing coaxiality deviation make it difficult for the external and internal gears to achieve the theoretically perfect parallel meshing. Under various operating conditions, the gear pair often exhibits an inclined meshing state, causing the contact mode between the external gear and the sealing plate to change from the designed surface-to-surface contact to point-to-surface contact.

[0003] This contact abnormality can cause two key failure problems: first, the sharp parts of the external gear tooth end repeatedly pierce the oil film boundary layer during high-speed operation, causing the continuity of the lubricating medium to be destroyed; second, local stress concentration is formed in the point contact area, accelerating abnormal wear of the end face.

[0004] The above problems directly lead to a decrease in the volumetric efficiency of the oil pump, while at the same time inducing an increased probability of sticking risk, accompanied by problems such as deterioration of NVH performance and contamination of the hydraulic system by wear debris, which seriously restrict the product's service life and reliability. Summary of the Invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] To this end, an embodiment of the present invention provides a gear modification method that can effectively suppress the drawbacks of the tilted meshing of standard gears.

[0007] An embodiment of the present invention further provides an oil pump.

[0008] An embodiment of the present invention further provides a vehicle.

[0009] The gear modification method according to an embodiment of the present invention includes:

[0010] Determine the pre-shaped gears of the oil pump and shape the outer gears;

[0011] Determine the modification position of the external gear, and perform modification on the two end faces of each tooth of the external gear in the axial direction within a preset range;

[0012] Determine the modified forms of the two end faces of the tooth in the axial direction, and the axial width of the tooth gradually decreases from the inside to the outside along the radial direction of the external gear;

[0013] Determine the tooth modification amount F_m, and calculate the modification amount based on the tooth tip circle diameter da, the modification starting circle diameter dm, and the offset angle β between the external gear and the shaft.

[0014] The gear modification method of an embodiment of the present invention implements axial width tapering modification (from tooth top to tooth root) on the tooth end of the external gear, thereby converting the point contact concentrated on the tooth top during inclined meshing into contact along the modified contour, thereby systematically solving the wear, efficiency attenuation and NVH problems caused by inclined meshing of the internal gear oil pump.

[0015] In some embodiments, the tooth modification is in the form of linear modification, and the modification amount F_m satisfies the relationship: F_m=(da-dm) / [2*tanβ].

[0016] In some embodiments, the tooth modification is in the form of parabolic modification, and the modification amount F_m satisfies the relationship: F_m=(da-dm) / [4*tanβ].

[0017] In some embodiments, the tooth modification is in the form of arc modification, and the modification amount F_m satisfies the relationship: F_m=(da-dm) / [2*sinβ / (cosβ+1)].

[0018] In some embodiments, the misalignment angle β between the external gear and the shaft satisfies the relationship: β=arctan(F_βx / B), where F_βx is the gear misalignment and B is the tooth width.

[0019] In some embodiments, the modified forms of the two end surfaces of the tooth in the axial direction are consistent.

[0020] In some embodiments, the preset range of the shaping is 10-20 μm.

[0021] In some embodiments, the actual modification amount F_m′ of the tooth and the calculated modification amount F_m satisfy the relationship: F_m≤F_m′≤(2-3)F_m.

[0022] The oil pump according to the embodiment of the present invention comprises:

[0023] a casing, the casing comprising a pump body and a pump cover, the pump body being detachably connected to the pump cover;

[0024] a gear assembly disposed in the pump body, the gear assembly comprising an internal gear and an external gear meshing with the internal gear, wherein both axial end faces of each tooth of the external gear are modified using the gear modification method described in any one of the above embodiments;

[0025] A radial compensation component is provided on the inner side of the internal gear

[0026] a drive shaft rotatably connected to the pump body and the pump cover, the external gear being sleeved on the drive shaft;

[0027] There are two sealing plates, which are respectively arranged on both sides of the gear assembly, and a sealing ring is provided between the side of the sealing plate away from the gear assembly and the pump body or pump cover.

[0028] The vehicle according to the embodiment of the present invention includes the oil pump described in the above embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 2 is a schematic structural diagram of an external gear according to an embodiment of the present invention.

[0030] Figure 2 2 is a schematic side view of an external gear according to an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of linear shaping according to an embodiment of the present invention.

[0032] Figure 4 Schematic diagram of parabola shaping according to an embodiment of the present invention.

[0033] Figure 5 Schematic diagram of arc shaping according to an embodiment of the present invention.

[0034] Figure 6 Schematic diagram of an explosion of an oil pump according to an embodiment of the present invention.

[0035] Figure 7 It is a schematic structural diagram of a gear assembly and a radial compensation assembly according to an embodiment of the present invention.

[0036] Figure 8 It is a schematic cross-sectional view of a partial structure of an oil pump according to an embodiment of the present invention.

[0037] Reference numerals:

[0038] 1- pump body, 2- pump cover, 3- gear assembly, 31- internal gear, 32- external gear, 4- drive shaft, 5- sealing plate, 6- sealing ring, 7- radial compensation assembly. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0040] The gear modification method according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0041] like Figures 1 to 8 As shown, the gear modification method according to an embodiment of the present invention includes:

[0042] S1, determine the pre-modified gear of the oil pump, select the outer gear 32 in the internal gear oil pump that is subject to end face wear as the modification object, and modify the outer gear 32 to specifically solve the point contact problem of the tooth top surface caused by inclined meshing in the background technology.

[0043] S2, determine the reshaping position of the external gear 32, and perform reshaping on the two axial end faces of each tooth of the external gear 32 within a preset range to ensure that when the external gear 32 is dynamically tilted toward the pump body 1 side or the pump cover 2 side, the tooth top is prevented from contacting the sealing plate 5, thereby reducing abnormal wear of the external gear 32.

[0044] S3: Determine the modified profile of the two axial end faces of the tooth (e.g., a straight line, circular arc, parabola, or other modified profile curve), with the axial width of the tooth gradually decreasing from the inside to the outside along the radial direction of the external gear 32. In other words, a modified profile structure is adopted in which the tooth width gradually decreases as the diameter increases, forming a chamfered or tapered profile at the tooth end.

[0045] During tilted meshing, the contact between the modified tooth tip area and the sealing plate 5 shifts from point contact to line contact along the modified profile, reducing peak contact stress. The tapered profile guides the lubricating oil film along the modified slope as the gear tilts, creating a wedge-shaped dynamic pressure effect. This increases the oil film thickness and reduces the probability of oil film rupture.

[0046] S4, determining the tooth modification amount F_m, and calculating the modification amount according to the tooth top circle diameter da, the modification starting circle diameter dm, and the misalignment angle β between the external gear 32 and the shaft, so as to achieve dynamic adaptation of the modification amount to the actual working conditions.

[0047] It can be understood that by implementing axial width tapering modification (from tooth root to tooth top) on the tooth end of the external gear 32, the point contact concentrated on the tooth top during inclined meshing is transformed into contact along the modified contour, thereby reducing the contact stress peak and wear depth.

[0048] The modified tapered profile (straight line / arc / parabola) forms a guiding slope of 0.5 to 1.5 mrad when the gear is tilted, shifting the tooth tip contact point toward the middle of the tooth width, avoiding the original sharp tooth tip area. CFD simulations show that the probability of oil film rupture is reduced from 92% to 17%, boundary lubrication time is reduced by 80%, oil film thickness is stabilized, and lubrication medium continuity is significantly improved.

[0049] The modified design optimizes the oil pump's volumetric efficiency decay rate, maintaining a stable mechanical efficiency above 94% over the long term (conventional designs drop to 88% in the later stages). Furthermore, wear debris contamination is reduced, the seizure rate is lowered, and product life is extended.

[0050] By eliminating the periodic impact between the tooth top and the sealing plate 5, the amplitude of high-frequency abnormal noise is reduced, and the noise power spectrum density is reduced, thereby solving the NVH degradation problem caused by wear in the background technology.

[0051] The modification calculation relates the gear geometry (da, dm) to the dynamic misalignment angle β, ensuring that the modification amount accurately matches the actual tilting condition, avoiding over- or under-modification.

[0052] Therefore, the gear modification method of the embodiment of the present invention systematically solves the wear, efficiency attenuation and NVH problems of the internal gear oil pump caused by inclined meshing through geometric optimization and dynamic parameter adaptation.

[0053] Alternatively, as Figure 3 As shown in , if the tooth modification form is linear modification, the modification amount F_m satisfies the relationship: F_m=(da-dm) / [2*tanβ]. Figure 4 As shown in , if the tooth modification form is parabolic modification, the modification amount F_m satisfies the relationship: F_m=(da-dm) / [4*tanβ]. Figure 5 As shown, if the tooth modification form is arc modification, the modification amount F_m satisfies the relationship: F_m=(da-dm) / [2*sinβ / (cosβ+1)].

[0054] The difference between da and dm can also be understood as 1 to 2.5 times the module m of the external gear. Figures 3 to 5 The solid line in the figure is the contour after modification, the dashed line (long dashed line) that is a parallel extension of the solid line is the contour without modification, and the length of the dashed line (short dashed line) that is at an angle to the solid line is the modification amount.

[0055] The process cost of linear shaping is lower than that of parabolic and circular shaping. The order of maximum contact stress from low to high is parabolic, circular, and linear. Therefore, linear shaping is suitable for low-speed, cost-sensitive applications, while parabolic and circular shaping are suitable for high-speed, cost-insensitive, and variable operating conditions.

[0056] It should be noted that all three shaping schemes solve the problem of tilt wear in the background technology through the geometric compensation mechanism, but the parabolic shaping is the best in terms of stress uniformity, the arc shaping is the most adaptable to dynamic misalignment angles, and the linear shaping has the best cost-effectiveness.

[0057] Furthermore, the misalignment angle β between the external gear 32 and the shaft satisfies the relationship: β=arctan(F_βx / B), where F_βx is the gear misalignment and B is the tooth width.

[0058] It can be understood that this formula associates the gear misalignment and tooth width through geometric relationships, quantifies the degree of dynamic axis offset between the gear and the shaft, converts the linear misalignment into an angle, facilitates mathematical association with the gear meshing parameters, and provides a theoretical basis for modification design.

[0059] The β angle reflects the instantaneous state of gear axis offset during actual operation. The amount of correction can be dynamically adjusted using the correction formula to compensate for misalignment under different operating conditions. When β exceeds a critical angle, the probability of oil film rupture increases dramatically. This formula can be used to provide early warning of gear system failure risks.

[0060] Gear misalignment is a linear representation of the gear axis offset, and its value is affected by the superposition of multiple error factors, such as tooth guide error, tooth top circle eccentricity, shaft bending deformation, journal installation error, manufacturing assembly error, operating environment factors, etc.

[0061] In some embodiments, as Figure 2 As shown, the profiles of the two end faces of the tooth in the axial direction are identical.

[0062] It's understandable that when both axial ends of a tooth adopt a consistent profile (e.g., a double-sided parabolic profile), the stress distribution in the contact areas on both sides becomes symmetrical during tilted meshing. This consistent profile allows for symmetrical machining processes (e.g., dual-wheel simultaneous grinding), which reduces machining time compared to separate processes that require different profiles on both sides.

[0063] In some embodiments, the preset range of the modification is 10-20 μm. This 10-20 μm modification range becomes the preferred solution for solving gear tilt wear by balancing mechanical performance, process feasibility, and efficiency requirements. The verification data is shown in the following table:

[0064]

[0065] In some embodiments, the actual modification amount F_m′ of the tooth and the calculated modification amount F_m satisfy the relationship: F_m≤F_m′≤(2-3)F_m.

[0066] It's clear that the relationship between the actual modification value F_m′ and the theoretical value F_m significantly improves the gear system's robustness to manufacturing errors, load fluctuations, and extreme operating conditions by introducing dynamic redundancy. Within the range of F_m′ = 2F_m to 3F_m, the system's lifespan can be extended without significantly sacrificing efficiency, while simultaneously reducing the sudden failure rate by an order of magnitude.

[0067] like Figures 6 to 8 As shown, the oil pump according to the embodiment of the present invention includes a casing, a gear assembly 3 , a radial compensation assembly 7 , a drive shaft 4 and a sealing plate 5 .

[0068] The casing includes a pump body 1 and a pump cover 2, which are detachably connected by bolts. A gear assembly 3 is disposed within the pump body 1 and includes an internal gear 31 and an external gear 32 meshing with the internal gear 31. Both axial end faces of each tooth of the external gear 32 are modified using the gear modification method described in any of the aforementioned embodiments.

[0069] A radial compensation assembly 7 is located inside the internal gear, such as a pressure block. The drive shaft 4 is rotatably connected to the pump body 1 and pump cover 2, and the external gear 32 is mounted on the drive shaft 4. Two sealing plates 5 are provided, one on each side of the gear assembly 3. A sealing ring 6 is provided between the side of the sealing plate 5 facing away from the gear assembly 3 and the pump body 1 or pump cover 2.

[0070] The oil pump in this embodiment of the present invention utilizes an innovative gear shaping method to fundamentally address the issues of abnormal end face wear and performance degradation caused by tilted meshing of internal gears. By applying a 10-20 μm tapered shaping (straight line / circular arc / parabola) to the tooth tips of the external gear 32, the tooth vertex contact during tilted meshing is transformed into line contact. This reduces peak contact stress, increases oil film thickness, and effectively prevents fretting wear caused by tooth tips piercing the oil film.

[0071] Actual testing has shown that the oil pump's volumetric efficiency attenuation rate is optimized, end face wear depth is reduced, NVH high-frequency noise amplitude is reduced, and design life is extended. Furthermore, this modification scheme, through formulaic dynamic adaptation, accommodates different misalignment angles under different operating conditions, while also reducing processing costs compared to traditional processes.

[0072] The vehicle according to the embodiment of the present invention includes the oil pump according to the above embodiment.

[0073] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0074] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0075] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0076] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0077] In the present invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless they are mutually inconsistent.

[0078] Although the above embodiments have been shown and described, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those skilled in the art are all within the scope of protection of the present invention.

Claims

1. An oil pump, characterized in that: include: a casing, the casing comprising a pump body and a pump cover, the pump body being detachably connected to the pump cover; a gear assembly disposed within the pump body, the gear assembly comprising an internal gear and an external gear meshing with the internal gear, wherein both axial end faces of each tooth of the external gear are modified; a radial compensation component, the radial compensation component being arranged on the inner side of the internal gear; a drive shaft rotatably connected to the pump body and the pump cover, the external gear being sleeved on the drive shaft; Sealing plates, two of which are provided on both sides of the gear assembly, and a sealing ring is provided between the side of the sealing plate away from the gear assembly and the pump body or pump cover; The external gear modification method includes: Determine the pre-shaped gears of the oil pump and shape the outer gears; Determine the modification position of the external gear, and perform modification on the two end faces of each tooth of the external gear in the axial direction within a preset range; Determine the modified forms of the two end faces of the tooth in the axial direction, and the axial width of the tooth gradually decreases from the inside to the outside along the radial direction of the external gear; Determine the tooth modification amount F_m, and calculate the modification amount based on the tooth tip circle diameter da, the modification starting circle diameter dm, and the misalignment angle β between the external gear and the shaft; The modification forms of the two end faces of the tooth in the axial direction are consistent; The actual tooth modification amount F_m′ and the calculated modification amount F_m satisfy the relationship: F_m≤F_m′≤(2~3)F_m.

2. The oil pump according to claim 1, characterized in that The tooth modification form is linear modification, and the modification amount F_m satisfies the relationship: F_m=(da-dm) / [2*tanβ].

3. The oil pump according to claim 1, characterized in that The tooth modification form is parabolic modification, and the modification amount F_m satisfies the relationship: F_m=(da-dm) / [4*tanβ].

4. The oil pump according to claim 1, characterized in that The tooth modification form is arc modification, and the modification amount F_m satisfies the relationship: F_m=(da-dm) / [2*sinβ / (cosβ+1)].

5. The oil pump according to any one of claims 2 to 4, characterized in that: The misalignment angle β between the external gear and the shaft satisfies the relationship: β=arctan(F_βx / B), where F_βx is the gear misalignment and B is the tooth width.

6. The oil pump according to claim 1, characterized in that The preset range of shaping is 10 to 20 μm.

7. A vehicle, characterized in that: The oil pump comprises the oil pump according to any one of claims 1 to 6.

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