Gear modification method, oil pump and vehicle

Abstract

The invention discloses a gear modification method, an oil pump and a vehicle. The gear modification method comprises the steps that a pre-modified gear of the oil pump is determined, and an external gear is modified; the modification position of the external gear is determined, and the two axial end faces of each tooth of the external gear are subjected to modification within a preset range; the modification forms of the two end faces, in the axial direction, of the teeth are determined, and the axial width of the teeth is gradually decreased from inside to outside in the radial direction of the outer gear; and the modification amount Fm of the teeth is determined, and the modification amount is calculated according to the addendum circle diameter da, the modification starting circle diameter dm and the dislocation angle beta between the outer gear and the shaft. According to the gear modification method disclosed by the embodiment of the invention, the axial width gradually-reduced modification (in the direction from the tooth root to the tooth crest) is carried out on the tooth end of the external gear, and point contact concentrated on the tooth crest during inclined meshing is converted into contact along the modification contour, so that the problems of abrasion, efficiency attenuation and NVH (Noise Vibration and Harshness) of the internal meshing gear oil pump caused by inclined meshing are systematically solved.

Description

Technical Field

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

[0002] During the actual operation of an internal gear oil pump in a vehicle, inherent factors such as the assembly clearance between the outer gear and the transmission shaft, the deformation of the support shaft under load, and the coaxiality deviation of the bearing position make it difficult for the outer gear and the inner gear to achieve theoretically perfect parallel meshing. Under multiple working conditions, the gear pair generally shows an inclined meshing state, resulting in the contact mode between the outer gear and the sealing plate changing from the designed surface-to-surface contact to point-to-surface contact.

[0003] This contact variation causes two key failure problems: First, the sharp part at the end of the outer gear repeatedly pierces the oil film boundary layer during high-speed operation, causing damage to the continuity of the lubricating medium; 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 reduction in the volumetric efficiency of the oil pump, an increase in the risk probability of jamming, and problems such as deterioration of NVH performance and contamination of the hydraulic system by wear debris, severely restricting the service life and reliability of the product. Summary of the Invention

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

[0006] To this end, an embodiment of the present invention provides a gear modification method, which can effectively suppress the disadvantages existing in the inclined meshing of standard gears.

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

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

[0009] The gear modification method of the embodiment of the present invention includes: Determine the gears to be pre-modified of the oil pump and modify the outer gear; Determine the modification positions of the outer gear and perform preset range modifications on the two end faces of each tooth of the outer gear in the axial direction; Determine the modification forms of the two end faces of the tooth in the axial direction, and the axial width of the tooth gradually decreases along the radial direction of the outer gear from the inside to the outside; Determine the modification amount F_m of the tooth, and calculate the modification amount according to the pitch circle diameter da, the starting circle diameter dm of the modification, and the misalignment angle β between the outer gear and the shaft.

[0010] The gear modification method according to the embodiments of the present invention systematically solves the problems of wear, efficiency attenuation, and NVH caused by inclined meshing of an internal gear oil pump by implementing axial width tapering modification (from the tooth tip to the tooth root) on the tooth ends of the external gear, converting the point contact concentrated at the tooth tip during inclined meshing into contact along the modified contour.

[0011] In some embodiments, the modification form of the tooth is linear modification, and the modification amount F_m satisfies the relation: F_m = (da - dm) / [2*tanβ].

[0012] In some embodiments, the modification form of the tooth is parabolic modification, and the modification amount F_m satisfies the relation: F_m = (da - dm) / [4*tanβ].

[0013] In some embodiments, the modification form of the tooth is circular arc modification, and the modification amount F_m satisfies the relation: F_m = (da - dm) / [2*sinβ / (cosβ + 1)].

[0014] In some embodiments, the misalignment angle β between the external gear and the shaft satisfies the relation: β = arctan(F_βx / B), where F_βx is the gear misalignment amount and B is the tooth width.

[0015] In some embodiments, the modification forms of the two end faces of the tooth in the axial direction are the same.

[0016] In some embodiments, the preset range of modification is 10 - 20 um.

[0017] In some embodiments, the actual modification amount F_m′ of the tooth and the calculated modification amount F_m satisfy the relation: F_m ≤ F_m′ ≤ (2 - 3)F_m.

[0018] The oil pump according to the embodiments of the present invention includes: A housing, the housing includes a pump body and a pump cover, and the pump body and the pump cover are detachably connected; A gear assembly, the gear assembly is arranged in the pump body, the gear assembly includes an internal gear and an external gear meshing with the internal gear, and the two end faces of each tooth of the external gear in the axial direction are modified, and the modification method is the gear modification method described in any one of the above embodiments; A radial compensation assembly, the radial compensation assembly is arranged inside the internal gear A drive shaft, the drive shaft is rotatably connected to the pump body and the pump cover, and the external gear is sleeved on the drive shaft; Sealing plates, there are two sealing plates, the two sealing plates are respectively arranged on both sides of the gear assembly, and a sealing ring is arranged between the side of the sealing plate away from the gear assembly and the pump body or the pump cover.

[0019] The vehicle according to an embodiment of the present invention includes the oil pump described in the above embodiment. Description of the Drawings

[0020] Figure 1 It is a schematic structural view of the external gear according to an embodiment of the present invention.

[0021] Figure 2 It is a schematic side view of the external gear according to an embodiment of the present invention.

[0022] Figure 3 It is a schematic view of the linear modification according to an embodiment of the present invention.

[0023] Figure 4 It is a schematic view of the parabolic modification according to an embodiment of the present invention.

[0024] Figure 5 It is a schematic view of the arc modification according to an embodiment of the present invention.

[0025] Figure 6 It is an exploded schematic view of the oil pump according to an embodiment of the present invention.

[0026] Figure 7 It is a schematic structural view of the gear assembly and the radial compensation assembly according to an embodiment of the present invention.

[0027] Figure 8 It is a schematic cross-sectional view of a partial structure of the oil pump according to an embodiment of the present invention.

[0028] Reference Signs: 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 Embodiments

[0029] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0030] The gear modification method according to an embodiment of the present invention will be described below with reference to the drawings.

[0031] As Figures 1 to 8 shown, the gear modification method according to an embodiment of the present invention includes: S1, determining the gears to be pre-modified of the oil pump. By selecting the external gear 32 that bears the end face wear in the internal meshing gear oil pump as the modification object, the external gear 32 is modified to specifically solve the problem of point contact at the tooth tip caused by inclined meshing in the background art.

[0032] S2. Determine the modification positions of the external gear 32, and perform modification within a preset range on the two end faces in the axial direction of each tooth of the external gear 32, so as to ensure that when the external gear 32 tilts dynamically towards the pump body 1 side or the pump cover 2 side, the tooth tip does not contact the sealing plate 5, and abnormal wear of the external gear 32 is reduced.

[0033] S3. Determine the modification forms of the two end faces in the axial direction of the teeth (for example, modification profile curves such as straight lines, arcs, parabolas, etc.), and the axial width of the teeth gradually decreases radially from the inside to the outside of the external gear 32. That is, a modification structure with the tooth width gradually tapering as the diameter increases is adopted to form a tooth end chamfer or a tapered profile.

[0034] During inclined meshing, the contact between the tooth tip modification area and the sealing plate 5 changes from point contact to line contact along the modification profile, and the peak value of the contact stress decreases. The tapered profile guides the lubricating oil film to form a wedge-shaped hydrodynamic effect along the modified inclined plane when the gear tilts, the thickness of the oil film increases, and the probability of oil film rupture decreases.

[0035] S4. Determine the modification amount F_m of the teeth, and calculate the modification amount based on the pitch diameter of the tooth tip da, the starting diameter of the modification dm, and the misalignment angle β between the external gear 32 and the shaft, so as to achieve the dynamic adaptation of the modification amount to the actual working conditions.

[0036] It can be understood that by implementing axial width tapering modification (from the tooth root to the tooth tip direction) on the tooth ends of the external gear 32, the point contact concentrated at the tooth tip during inclined meshing is transformed into contact along the modification profile, and the peak value of the contact stress and the wear depth are reduced.

[0037] The modified tapered profile (straight line / arc / parabola) forms a guiding inclined plane of 0.5 - 1.5 mrad when the gear tilts, causing the tooth end contact point to shift towards the middle of the tooth width and avoiding the original sharp tooth tip area. CFD simulation shows that the probability of oil film rupture decreases from 92% to 17%, the boundary lubrication time is reduced by 80%, the oil film thickness is stable, and the continuity of the lubricating medium is significantly improved.

[0038] The modification design optimizes the decay rate of the volumetric efficiency of the oil pump, and the mechanical efficiency is stably above 94% for a long time (it drops to 88% in the later stage of conventional design). At the same time, the pollution of wear debris is reduced, the jamming failure rate is decreased, and the product life is extended.

[0039] By eliminating the periodic impact between the tooth tip and the sealing plate 5, the amplitude of the high-frequency abnormal noise decreases, the noise power spectral density drops, and the NVH deterioration problem caused by wear in the background technology is solved.

[0040] The calculation of the modification amount correlates the gear geometric parameters (da, dm) with the dynamic misalignment angle β to ensure that the modification amount accurately matches the actual inclined working conditions and avoids over-modification or under-modification.

[0041] Thus, the gear modification method according to the embodiments of the present invention systematically solves the problems of wear, efficiency decay, and NVH caused by inclined meshing of internal gear oil pumps through geometric optimization and dynamic parameter adaptation.

[0042] Optionally, as Figure 3 shown, if the modification form of the tooth is linear modification, the modification amount F_m satisfies the relational expression: F_m = (da - dm) / [2*tanβ]. As Figure 4 shown, if the modification form of the tooth is parabolic modification, the modification amount F_m satisfies the relational expression: F_m = (da - dm) / [4*tanβ]. As Figure 5 shown, if the modification form of the tooth is circular arc modification, the modification amount F_m satisfies the relational expression: F_m = (da - dm) / [2*sinβ / (cosβ + 1)].

[0043] Among them, 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

[0044] is the modified contour, the dashed line (long dashed line) of the parallel extended part of the solid line is the unmodified contour, and the length of the dashed line (short dashed line) with an angle with the solid line is the modification amount.

[0045] It should be noted that all three modification schemes solve the inclined wear problem in the background technology through the geometric compensation mechanism. However, the parabolic modification is optimal in terms of stress distribution, the circular arc modification has the strongest adaptability to the dynamic misalignment angle, and the linear modification has the best cost performance.

[0046] Furthermore, the misalignment angle β between the external gear 32 and the shaft satisfies the relational expression: β = arctan(F_βx / B), where F_βx is the gear misalignment amount and B is the tooth width.

[0047] It can be understood that this formula correlates the gear misalignment amount and the tooth width through geometric relationships, quantifies the degree of dynamic axis offset between the gear and the shaft, converts the linear misalignment amount into an angle, facilitates the mathematical association with the gear meshing parameters, and provides a theoretical basis for the modification design.

[0048] The β angle reflects the instantaneous state of the gear axis offset during actual operation. The modification amount can be dynamically adjusted in combination with the modification formula to compensate for the misalignment effect under different working conditions. When β exceeds the critical angle, the probability of oil film rupture increases sharply, and the formula can be used to warn of the failure risk of the gear system.

[0049] The misalignment of the gear is a linear representation of the offset of the gear axis, and its value is affected by the superposition of multiple error factors. For example, helix error, eccentricity of the addendum circle, shaft bending deformation, journal installation error, manufacturing and assembly error, operating environment factors, etc.

[0050] In some embodiments, as Figure 2 shown, the modification forms of the two end faces of the tooth in the axial direction are the same.

[0051] It can be understood that when the axial end faces of the tooth adopt the same modification form (such as bilateral parabolic modification), when the gear meshes obliquely, the stress distribution in the contact areas on both sides is symmetric. The same modification form allows the use of symmetric machining processes (such as synchronous grinding with two grinding wheels), and compared with the scheme of machining different profiles on both sides step by step, the machining time is shortened.

[0052] In some embodiments, the preset range of modification is 10 - 20 μm. The 10 - 20 μm modification range has become the preferred solution for solving the problem of inclined wear of gears by balancing mechanical properties, process feasibility and efficiency requirements. The verification data is as follows in the table:

[0053] 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.

[0054] It can be understood that the relationship between the actual modification amount F_m′ and the theoretical value F_m significantly improves the robustness of the gear system to manufacturing errors, load fluctuations and extreme working conditions by introducing dynamic redundancy. In the range of F_m′ = 2F_m - 3F_m, the system can extend the service life without significantly sacrificing efficiency, and at the same time reduce the sudden failure rate by one order of magnitude.

[0055] As Figures 6 to 8 shown, the oil pump of the embodiment of the present invention includes a housing, a gear assembly 3, a radial compensation assembly 7, a drive shaft 4 and a sealing plate 5.

[0056] The housing includes a pump body 1 and a pump cover 2, and the pump body 1 and the pump cover 2 are detachably connected by bolts. The gear assembly 3 is arranged in the pump body 1, the gear assembly 3 includes an internal gear 31 and an external gear 32 meshing with the internal gear 31, and the two end faces of each tooth of the external gear 32 in the axial direction are modified, and the modification method is the gear modification method according to any one of the above embodiments.

[0057] The radial compensation component 7 is arranged inside the internal gear, for example, a monthly pressing block. The drive shaft 4 is rotatably connected to the pump body 1 and the pump cover 2, and the external gear 32 is sleeved on the drive shaft 4. There are two sealing plates 5, and the two sealing plates 5 are respectively arranged on both sides of the gear assembly 3, and a sealing ring 6 is arranged between the side of the sealing plate 5 far from the gear assembly 3 and the pump body 1 or the pump cover 2.

[0058] For the oil pump according to the embodiment of the present invention, through an innovative gear modification method, the problems of abnormal end face wear and performance deterioration caused by inclined meshing of the internal meshing gear are fundamentally solved. By implementing a tapered modification (linear / arc / parabolic) of 10 - 20 um at the tooth end of the external gear 32, the tooth apex contact during inclined meshing is transformed into line contact, the peak value of the contact stress is decreased, the oil film thickness is increased, and the fretting wear caused by the tooth end piercing the oil film is effectively inhibited.

[0059] Actual tests show that the decay rate of the volumetric efficiency of the oil pump is optimized, the depth of end face wear is reduced, the amplitude of NVH high-frequency abnormal noise is decreased, and the design life is extended. At the same time, this modification scheme is dynamically adapted through formulas to be compatible with misalignment angles under different working conditions, and the processing cost is reduced compared with the traditional process.

[0060] The vehicle according to the embodiment of the present invention includes the oil pump in the above embodiment.

[0061] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is 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 thus cannot be understood as a limitation to the present invention.

[0062] In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0063] In the present invention, unless otherwise clearly defined or limited, terms such as "installed", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication between two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] In the present invention, unless otherwise clearly defined or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0065] In the present invention, terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions 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 a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0066] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the protection scope of the present invention.

Claims

1. A gear modification method, characterized in that, Including: Determine the pre-modified gear of the oil pump and modify the external gear. Determine the modification position of the external gear, and perform pre-set range modification on the two end faces of each tooth of the external gear in the axial direction respectively. Determine the modification form of the two end faces of the tooth in the axial direction, and the axial width of the tooth gradually decreases along the radial direction of the external gear from the inside to the outside. Determine the modification amount F_m of the tooth. Calculate the modification amount according to the pitch diameter of the addendum circle da, the diameter of the starting circle of modification dm, and the misalignment angle β between the external gear and the shaft.

2. The gear modification method according to claim 1, wherein The modification form of the tooth is linear modification, and the modification amount F_m satisfies the relationship: F_m = (da - dm) / [2*tanβ].

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

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

5. The gear modification method according to any one of claims 2-4, 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 amount and B is the tooth width.

6. The gear modification method according to claim 1, wherein The modification forms of the two end faces of the tooth in the axial direction are the same.

7. The gear modification method according to claim 1, wherein The pre-set range of modification is 10 - 20 um.

8. The gear modification method according to claim 1, wherein 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.

9. An oil pump, characterized in that, Including: A housing, the housing includes a pump body and a pump cover, and the pump body and the pump cover are detachably connected. A gear assembly, the gear assembly is arranged in the pump body, the gear assembly includes an internal gear and an external gear meshing with the internal gear, and the two end faces of each tooth of the external gear in the axial direction are modified, and the modification method is the gear modification method according to any one of claims 1 - 8. A radial compensation assembly, the radial compensation assembly is arranged inside the internal gear. A drive shaft, the drive shaft is rotatably connected with the pump body and the pump cover, and the external gear is sleeved on the drive shaft. Sealing plates, there are two sealing plates, the two sealing plates are respectively arranged on both sides of the gear assembly, and a sealing ring is arranged between the side of the sealing plate away from the gear assembly and the pump body or the pump cover.

10. A vehicle, characterized in that, Including the oil pump according to claim 9.

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