Differential and vehicle

Abstract

The application discloses a differential mechanism and a vehicle, and the differential mechanism comprises a differential mechanism shell, a planetary shaft connected with the differential mechanism shell, and two planetary gears rotationally connected with the planetary shaft. The two planetary gears are each provided with an axle hole, and the two planetary gears are sleeved on two ends of the planetary shaft through the axle holes to be rotationally connected with the planetary shaft. The profile line of the axle hole is a super-elliptical drum type line, the planetary shaft is more uniformly distributed in the differential working condition of the whole vehicle, the maximum surface pressure is not more than 300 MPa, and the planetary shaft will not be abraded.

Description

Technical Field

[0001] This application belongs to the field of differential technology, and particularly relates to a differential and a vehicle. Background Technology

[0002] The differential is a core component of the vehicle's drive axle. Its core function is to transmit power to both wheels while allowing the left and right wheels to rotate at different speeds when turning, thereby ensuring smooth vehicle steering.

[0003] Planetary gears are key load-bearing and moving components within the differential. During differential operation, relative sliding occurs between the planetary gears and the planetary shaft surfaces. The frictional power δ generated by this relative sliding is positively correlated with the contact pressure P on the planetary shaft surface and the relative rotational speed n between the planetary gears and the planetary shaft. The relative rotational speed n is determined by the overall vehicle differential operating conditions. The structure of the mating area between the planetary gears and the planetary shaft affects the contact pressure P on the planetary shaft surface. If the local surface pressure on the planetary shaft is too high, it can lead to wear or seizing at that location.

[0004] Therefore, it is necessary to design the structure of the mating point between the planetary gear and the planetary shaft to reduce the problems of planetary shaft wear or sintering. Summary of the Invention

[0005] This application aims to at least solve one of the technical problems existing in the prior art. To this end, this application proposes a differential and a vehicle in which the planetary shaft does not wear under vehicle differential conditions.

[0006] In a first aspect of this application, a differential is provided, comprising: a differential housing; a planetary shaft connected to the differential housing; and two planetary gears, each having a shaft hole; the two planetary gears are respectively sleeved on both ends of the planetary shaft through the shaft hole to be rotatably connected to the planetary shaft; wherein the outline of the shaft hole is a superelliptical drum-shaped line.

[0007] In some embodiments, the equation of the hyperelliptical drum-shaped line is: Where, a is the length of the shaft hole, b is the set drum shape coefficient, the exponent n is 2~5, x is the axial coordinate of the shaft hole contour line, and y is the radial coordinate of the shaft hole contour line.

[0008] In some embodiments, the drum shape coefficient b is: b = (0.001~0.0015) * a.

[0009] In some embodiments, an oil reservoir is provided in the area of ​​the planetary shaft that rotates with the planetary gear.

[0010] In some embodiments, the length of the oil reservoir is the same as the length of the shaft hole; and / or, the width of the oil reservoir is 15% to 25% of the circumference of the planetary shaft.

[0011] In some embodiments, the planetary shaft has a cross-section; the oil reservoir is formed by the cross-section and stepped structures located at both ends of the cross-section along its axial direction.

[0012] In some embodiments, the depth of the oil reservoir is 0.2 mm to 0.8 mm; and / or, the connection between the cut surface and the axial surface of the planetary shaft is provided with a transition fillet.

[0013] In some embodiments, the surface roughness Ra of the planetary shaft is 0.4 μm to 0.8 μm.

[0014] In some embodiments, the surface of the planetary shaft is provided with a nickel plating layer; the plating depth of the nickel plating layer is 0.01 mm to 0.03 mm, and / or the hardness of the nickel plating layer is not less than 750 HV0.05.

[0015] In a second aspect of this application, a vehicle is provided that includes the differential described in the first aspect.

[0016] A differential according to one or more embodiments of this application includes a differential housing, a planetary shaft connected to the differential housing, and two planetary gears rotatably connected to the planetary shaft. Each planetary gear has a shaft hole, and the two planetary gears are respectively fitted onto both ends of the planetary shaft through the shaft hole for rotatable connection. The contour line of the shaft hole is a super-elliptical drum-shaped line, resulting in a more uniform surface pressure distribution on the planetary shaft under vehicle differential conditions, with a maximum surface pressure not exceeding 300 MPa, preventing wear on the planetary shaft. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the differential structure in one or more embodiments of this application is shown.

[0019] Figure 2 It shows Figure 1 A full cross-sectional view of the differential.

[0020] Figure 3 It shows Figure 1 The force structure diagram of the planetary gears and planetary shafts in the differential.

[0021] Figure 4 It shows Figure 1 A schematic diagram of the differential in the vehicle differential operation.

[0022] Figure 5 A schematic diagram of the planetary gears of the differential in one or more embodiments of this application is shown.

[0023] Figure 6 It shows the relationship with Figure 5 Simulation diagram of the surface pressure of the planetary shaft that mates with the shaft hole of the planetary gear.

[0024] Figure 7 A schematic diagram of the outline of the shaft hole of a planetary gear in related technology 1 is shown.

[0025] Figure 8 It shows the relationship with Figure 7 Simulation diagram of the surface pressure of the planetary shaft that mates with the shaft hole of the planetary gear.

[0026] Figure 9 A schematic diagram of the outline of the shaft hole of a planetary gear in related technology 2 is shown.

[0027] Figure 10 It shows the relationship with Figure 9 Simulation diagram of the surface pressure of the planetary shaft that mates with the shaft hole of the planetary gear.

[0028] Figure 11 A schematic diagram of the planetary shaft of the differential is shown in one or more embodiments of this application.

[0029] Figure 12 It shows Figure 11 A top view of the planetary axis.

[0030] Figure 13 A schematic diagram of the vehicle structure is shown in one or more embodiments of this application.

[0031] Explanation of reference numerals in the attached drawings: 1000-Vehicle; 100-Differential; 110-Differential housing; 111-Left housing; 112-Right housing; 120-Planetary shaft; 121-Oil reservoir; 1211-Cut surface; 1212-Stepped structure; 122-Locking hole; 130-Planetary gear; 131-Shaft hole; 140-Shim; 150-Locking pin; 160-Half-shaft gear; 170-Main reduction gear; 200-Power system; 300-Wheel; 400-Half-shaft; 500-Body body. Detailed Implementation

[0032] To enable those skilled in the art to more clearly understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] Furthermore, reference numerals and / or reference letters may be repeated in different examples in this application. Such repetition is for simplification and clarity purposes and does not in itself indicate a relationship between the various embodiments and / or settings discussed. In addition, this application provides examples of various specific processes and materials; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0034] The specific technical solutions of this application will be described in detail below with reference to the accompanying drawings, which are not necessarily drawn to scale. Similar or identical reference numerals may be used to designate the same or similar parts in different drawings. The use of similar or identical reference numerals in different drawings does not mean that all drawings including similar or identical reference numerals constitute a single or the same embodiment. The accompanying drawings illustrate the various embodiments discussed in this application in a generalized manner, by way of example and not limitation.

[0035] Please see Figure 1 and Figure 2 According to a first aspect of this application, a differential 100 is provided, which includes at least a differential housing 110, a planetary shaft 120, and two planetary gears 130. The differential housing 110 can be an integral or split structure. In some embodiments, the differential housing 110 includes a left housing 111 and a right housing 112 connected by bolts. The left housing 111 and the right housing 112 together form an installation space, in which components such as the planetary shaft 120 and the planetary gears 130 are located. A main reduction gear 170 is fixedly connected to the differential housing 110. The main reduction gear 170 meshes with the power output gear of an external power system 200, transmitting the power output from the power system 200 to the differential housing 110. The main reduction gear 170 drives the differential housing 110 to rotate as a whole. The main reduction gear 170 can be fixedly connected to the differential housing 110 by screws. For example, the main reduction gear 170, the left housing 111 and the right housing 112 can be fixedly connected by screws at the same time. In some embodiments, the main reduction gear 170 can also be integrally formed on the differential housing 110. For example, the main reduction gear 170 can be integrally formed on the left housing 111.

[0036] The planetary shaft 120 is connected to the differential housing 110. Specifically, both ends of the planetary shaft 120 are fixedly connected to the differential housing 110 via key connections, interference fits, or other methods, allowing the planetary shaft 120 to rotate together with the differential housing 110. The planetary shaft 120 passes through the differential housing 110. To prevent the planetary shaft 120 from detaching from the differential housing 110, please refer to [reference needed]. Figure 2 In some embodiments, the planetary shaft 120 has a through-hole locating hole 122 for mounting a locating pin 150. The locating pin 150 passes through both the planetary shaft 120 and the differential housing 110, thereby positioning the planetary shaft 120 and the differential housing 110. The locating pin 150 prevents relative movement between the planetary shaft 120 and the differential housing 110. In other embodiments, if the screw connecting the main reduction gear 170 and the differential housing 110 overlaps with the planetary shaft 120 axially, the screw can prevent movement of the planetary shaft 120, and in this case, the locating pin 150 may not be necessary.

[0037] Please see Figure 2 Both planetary gears 130 are provided with shaft holes 131, and the two planetary gears 130 are respectively sleeved on both ends of the planetary shaft 120 through the shaft holes 131 to be rotatably connected with the planetary shaft 120. Compared with a differential in which the two planetary gears 130 are respectively mounted on two short shafts, the differential 100 provided in this application has fewer parts, is easier to assemble, and has a lower cost.

[0038] In some embodiments, the differential 100 is a bevel gear differential 100, and both planetary gears 130 are bevel gears, mounted on a planetary shaft 120 in a back-to-back (small end to small end) configuration. Please continue reading. Figure 2 In some embodiments, a shim 140 is provided on the outer side of the two planetary gears 130. The shim 140 is sleeved on the planetary shaft 120 and is located between the planetary gear 130 and the differential housing 110, specifically between the large end face of the planetary gear 130 and the differential housing 110. The shim 140 is generally made of copper alloy or composite material sheet, which can precisely control the axial clearance between the planetary gear 130 and the differential housing 110 and bear the axial load of the planetary gear 130. Furthermore, the shim 140 is wear-resistant and can prevent direct frictional contact between the planetary gear 130 and the differential housing 110.

[0039] Please continue reading. Figure 2The differential 100 also includes two half-shaft gears 160, each meshing with two planetary gears 130 simultaneously. The left half-shaft gear 160 is connected to the left half-shaft 400 of the vehicle 1000 via a spline drive, and the left half-shaft 400 drives the left wheel. The right half-shaft gear 160 is connected to the right half-shaft 400 of the vehicle 1000 via a spline drive, and the right half-shaft 400 drives the right wheel.

[0040] In straight-line driving, the left and right wheels 300 rotate at the same speed, and the planetary gear 130 and planetary shaft 120 are relatively stationary, rotating together with the differential housing 110. When the vehicle turns (differential 100 is in differential mode), the left and right wheels 300 rotate at different speeds, creating a speed difference. At this time, the planetary gear 130 will rotate relative to the planetary shaft 120. The planetary gear 130 bears the axial load Fa, radial load Fr, and circumferential load Ft applied by the half-shaft gears 160. Since each planetary gear 130 is always meshed with the two half-shaft gears 160, the radial load Fr borne by the planetary gear 130 cancels each other out, and the radial load Fr is not transmitted to the planetary shaft 120, thus not causing bending deformation of the planetary shaft 120. The axial load Fa acts on the shim 140 through the planetary gear 130, and the direction of the axial load Fa is parallel to the axial direction of the planetary shaft 120. Therefore, the axial load Fa will not cause bending deformation of the planetary shaft 120. The force F exerted by the planetary gear 130 on the planetary shaft 120 mainly originates from the circumferential load Ft (also known as circumferential force) borne by the planetary gear 130. The force F exerted by the planetary gear 130 is the resultant force of the circumferential forces of the planetary gear 130, and the direction of this force F is the radial direction of the planetary shaft 120.

[0041] Figure 3 The force structure diagram of planetary gear 130 and planetary shaft 120 is shown. Please refer to [link / reference]. Figure 3 The two planetary gears 130 exert forces F on the planetary shaft 120 in different directions. Under the action of the forces F from the two planetary gears 130, the planetary shaft 120 will exhibit an S-shaped bending deformation, such as... Figure 4 As shown. This bending deformation causes localized contact between the planetary shaft 120 and the planetary gear 130 at the edge or center of the shaft hole 131. The load on the planetary gear 130 is concentrated at this localized contact point. The localized frictional power between the planetary shaft 120 and the planetary gear 130 exceeds the lubrication capacity of the differential 100, leading to severe wear and failure at the localized contact point during actual operation.

[0042] Please continue reading. Figure 3The average pressure P on the contact surface between planetary shaft 120 and planetary gear 130 is P = F / A, where A = L * D. The relative sliding velocity V between the surfaces of planetary gear 130 and planetary shaft 120 is V = nπD / 12. The frictional power δ between planetary gear 130 and planetary shaft 120 is δ = P * V. That is, the frictional power δ generated by relative sliding is positively correlated with the contact pressure P on the surface of planetary shaft 120 and the relative rotational speed n between planetary gear 130 and planetary shaft 120. Therefore, the contact pressure P on the surface of planetary shaft 120 can be controlled at a low level through the structural design of the shaft hole 131 of planetary gear 130, ensuring that planetary shaft 120 does not experience wear.

[0043] For this purpose, please refer to Figure 5 In the differential 100 of this application, the contour line of the shaft hole 131 of the planetary gear 130 is a super-elliptical drum-shaped line. The surface pressure distribution of the planetary shaft 120 under vehicle differential operating conditions is as follows: Figure 6 As shown, the contour line of the shaft hole 131 adopts a super-elliptical drum-shaped line. The load of the planetary gear 130 is mainly concentrated at the local contact position between the planetary shaft 120 and the edge of the shaft hole 131 (the yellow area at the edge). The load of the planetary gear 130 is also widely distributed in the middle part between the planetary shaft 120 and the shaft hole 131 (the light blue area in the middle funnel shape). Figure 6 It can be seen that when the contour line of the shaft hole 131 adopts a super-elliptical drum-shaped line, the surface pressure distribution of the planetary shaft 120 is more uniform, and the maximum surface pressure of the planetary shaft 120 does not exceed 300 MPa. Figure 6 The maximum surface pressure detected is 247 MPa, located at the outer edge of the shaft hole 131. The surface pressure at each part of the planetary shaft 120 that contacts the shaft hole 131 is reduced to a safe level. The lubricating oil can lubricate each part of the planetary shaft 120 that contacts the shaft hole 131, so that the planetary shaft 120 will not wear.

[0044] Figure 7 and Figure 9 Two other planetary gear 130 shaft hole 131 structures in the related art are shown. These planetary gears 130 are identical to those in this application except for the outline of the shaft hole 131. The shape, size, and structure of the adapted planetary shaft 120 are also completely identical to those in this application.

[0045] Please see Figure 7 In related technology one, the planetary gear 130 has a cylindrical shaft hole 131 with chamfers at both axial ends. The outline of the shaft hole 131 is a line shape consisting of beveled lines at both ends and a straight line in the middle. However, this chamfered planetary gear 130 still cannot eliminate the problem of excessive surface pressure caused by localized contact between the edge of the shaft hole 131 and the planetary shaft 120. In actual use, it can still lead to abnormal wear in localized contact areas of the planetary shaft 120. For example... Figure 8As shown, the load on the planetary gear 130 is concentrated at the local contact point between the planetary shaft 120 and the edge of the planetary gear 130 shaft hole 131. The maximum pressure can reach 586 MPa, and severe wear will occur at the local contact point, leading to failure.

[0046] Please see Figure 9 In the related technology 2, the axial ends of the shaft hole 131 of the planetary gear 130 are still chamfered, but the middle section of the outline of the shaft hole 131 is an arc, and the outline of the shaft hole 131 is a line type with inclined lines at both ends and a straight line in the middle. For example... Figure 10 As shown, this design scheme with chamfered corners and rounded transitions will cause the pressure to be concentrated in the middle of the contact position between the planetary shaft 120 and the planetary gear 130. The local pressure can reach up to 725 MPa, which is significantly beyond the lubrication capacity of the differential 100. Ultimately, this will also cause wear on the planetary shaft 120 during use.

[0047] The differential 100 of this application has a shaft hole 131 with a super-elliptical drum-shaped profile, resulting in a more uniform surface pressure distribution on the planetary shaft 120 under vehicle differential conditions. Testing showed that the maximum surface pressure of the planetary shaft 120 is only 247 MPa. This is a reduction of 339 MPa compared to the maximum pressure of 586 MPa in related technology one, and a reduction of 478 MPa compared to the maximum pressure of 725 MPa in related technology two. The wear load on the planetary shaft 120 of the differential 100 of this application is significantly reduced.

[0048] In some embodiments, the equation of the hyperelliptical drum-shaped line is: .

[0049] Where 'a' is the length of the shaft hole 131 (which can be equivalent to...) Figure 3 The contact length L in the figure generally satisfies the following relationship with the diameter D of the planetary shaft 120: L = 1.1~1.5D). b is the set drum shape coefficient. The exponent n is 2~5, and the exponent n can be 2, 3, 4 or 5. x is the axial coordinate of the contour line of the shaft hole 131, and y is the radial coordinate of the contour line of the shaft hole 131.

[0050] In some embodiments, the drum shape coefficient b is: b = (0.001~0.0015) * a. b can be 0.001a, 0.0011a, 0.0012a, 0.0013a, 0.0014a, 0.0015a, etc. b is much smaller than a, resulting in a flatter overall shape for the hyperelliptical drum shape, thus avoiding... Figure 9The chamfered and rounded transition design concentrates the pressure on the middle of the contact area between the planetary shaft 120 and the planetary gear 130, significantly reducing the surface pressure in the middle area corresponding to the planetary shaft 120 and the shaft hole 131. Although the super-elliptical drum-shaped line is generally flat, the middle section of the super-elliptical drum-shaped line is not a straight line. Compared to... Figure 7 The line shape shown, with sloping lines at both ends and a straight line in the middle, features a slightly bulging middle section of the hyperelliptical drum-shaped line. This allows the load to be effectively transmitted between the planetary shaft 120 and the shaft hole 131, preventing the load on the planetary gear 130 from being concentrated entirely at the edge of the local contact point between the planetary shaft 120 and the shaft hole 131. In summary, the shaft hole 131 of this application adopts a hyperelliptical drum-shaped line, which enables the planetary shaft 120 to achieve [unclear meaning - possibly "transmission of load"]. Figure 6 The uniform surface pressure distribution is shown.

[0051] Wear on planetary shaft 120 stems from both excessive surface pressure and insufficient lubrication. For further information, please refer to... Figure 10 In some embodiments, the planetary shaft 120 is also provided with an oil reservoir 121. Since two planetary gears 130 are mounted on the planetary shaft 120, oil reservoirs 121 are provided in both areas of the planetary shaft 120 that rotatably engage with the planetary gears 130. These oil reservoirs 121 mate with shaft holes 131 that employ ultra-elliptical drum-shaped profiles, ensuring sufficient lubrication of the surfaces of the planetary gears 130 and the planetary shaft 120, thus preventing wear.

[0052] Combination Figure 6 The planetary shaft 120 is clearance-fitted with the shaft hole 131, which has an ultra-elliptical drum-shaped profile. The main pressure-bearing areas on the surface of the planetary shaft 120 are distributed in the regions corresponding to the two axial ends of the shaft hole 131. The pressure in the middle section of the contact area between the planetary shaft 120 and the shaft hole 131 is relatively low. When the planetary gear 130 rotates relative to the planetary shaft 120, it generates an oil pumping effect. The pressure in the middle section of the contact area is relatively low. During differential operation in the differential 100, the lubricating oil stored in the oil reservoir 121 will preferentially enter the lower pressure area in the middle of the contact area. The oil between the planetary gear 130 and the planetary shaft 120 will preferentially enter the low-pressure area in the middle section of the contact area, and then enter the high-pressure areas on both sides under the contact pressure of the planetary shaft 120 and the gear. This forms a complete oil film on the surface of the planetary shaft 120. The entire contact area between the planetary shaft 120 and the planetary gear 130 is isolated by an oil film, avoiding direct metal-to-metal contact wear between the surfaces of the planetary shaft 120 and the planetary gear 130.

[0053] Please see Figure 11In some embodiments, the length of the oil reservoir 121 is the same as the length of the shaft hole 131, and the positions of the oil reservoir 121 and the shaft hole 131 are completely corresponding. The oil stored in the oil reservoir 121 can cover the entire contact area between the planetary shaft 120 and the planetary gear 130. The lubricating oil wets the friction surface of the planetary shaft 120 and improves the lubrication of the planetary shaft 120 surface.

[0054] In some embodiments, the width (radial dimension) of the oil reservoir 121 is 15% to 25% of the circumference (πD) of the planetary shaft 120, for example, 0.15πD, 0.16πD, 0.17πD, 0.18πD, 0.19πD, 0.2πD, 0.21πD, 0.22πD, 0.23πD, 0.24πD, 0.25πD, etc. The smaller width of the oil reservoir 121 avoids excessively reducing the structural strength of the planetary shaft 120. As a further embodiment, the two oil reservoirs 121 can be located on the same generatrix of the planetary shaft 120, that is, the two oil reservoirs 121 are in the same circumferential position. Of course, in other embodiments, the two oil reservoirs 121 can also be set to have a circumferential angle, for example, the two oil reservoirs 121 are located on two radially opposite generatrixes, that is, the two oil reservoirs 121 are 180° apart circumferentially.

[0055] The oil reservoir 121 can be machined onto the planetary shaft 120 or formed directly onto the planetary shaft 120 (e.g., the planetary shaft 120 is cast). The oil reservoir 121 can be a recessed groove into the planetary shaft 120. In other embodiments, the oil reservoir 121 can also be an open groove to facilitate the outflow of oil from the oil reservoir 121.

[0056] Please see Figure 11 and Figure 12 In one embodiment, the planetary shaft 120 has a cut surface 1211 that does not penetrate the end of the planetary shaft 120, thus forming two stepped structures 1212 at both ends of the cut surface 1211. To reduce stress, the connection between the cut surface 1211 and the stepped structure 1212 can be rounded. In some embodiments, a transition fillet can also be provided at the connection between the cut surface 1211 and the axial surface of the planetary shaft 120. The cut surface 1211 can be a flat cut surface 1211 (the cut surface 1211 is a plane) or an arc-shaped cut surface 1211 (recessed inwards towards the planetary shaft 120), and this application does not impose any limitations.

[0057] The oil reservoir 121 is formed by a cross-section 1211 and stepped structures 1212 located at both ends of the cross-section 1211 along its axial direction. In other words, the oil reservoir 121 has only two walls, namely the stepped structures 1212. The width direction of the oil reservoir 121 has no walls. The oil stored in the oil reservoir 121 can flow circumferentially along the width direction of the oil reservoir 121, thereby covering the entire contact area between the planetary shaft 120 and the planetary gear 130.

[0058] In some embodiments, the depth of the oil storage tank 121 is 0.2mm to 0.8mm, for example, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.75mm, 0.8mm, etc. Since the oil storage tank 121 is formed by a cross-section 1211 and stepped structures 1212 located at both axial ends of the cross-section 1211, the depth of the oil storage tank 121 varies at different widths. In some embodiments, the deepest point of the oil storage tank 121 can be used as the depth of the oil storage tank 121.

[0059] To reduce heat generation, the surface roughness of the planetary shaft 120 should not be too high. Please refer to [link / reference]. Figure 12 In some embodiments, the surface roughness Ra of the planetary shaft 120 satisfies Ra = 0.4 μm to 0.8 μm. In some embodiments, this roughness Ra can be achieved by electroplating nickel (depositing a layer of nickel on the metal surface through electrochemical action) or electroless nickel plating (also known as electroless nickel plating or autocatalytic nickel plating, in which nickel ions in an aqueous solution are reduced by a reducing agent and deposited onto the metal surface under certain conditions), so that a nickel plating layer is formed on the surface of the planetary shaft 120. The nickel plating layer can not only improve the surface smoothness of the planetary shaft 120, but also improve the wear resistance of the planetary shaft 120 surface.

[0060] In some embodiments, the nickel plating depth is 0.01 mm to 0.03 mm. In some embodiments, the hardness of the nickel plating is not less than 750 HV0.05 (low-load Vickers hardness, test force is 0.05 kgf). The high hardness of the nickel plating ensures the wear resistance of the planetary shaft 120 surface, enabling it to maintain good performance even in harsh environments.

[0061] Please see Figure 13 According to a second aspect of this application, a vehicle 1000 is provided, including the differential 100 described in the first aspect. The differential 100 is mounted on the body 500 of the vehicle 1000. The main reduction gear 170 of the differential 100 meshes with the output gear of the power system 200 of the vehicle 1000, inputting power to the power system 200. The half-shaft gear 160 of the differential 100 is connected to the half-shaft 400 in a transmission connection, or the half-shaft gear 160 of the differential 100 is integrally formed with the half-shaft 400, and the power of the half-shaft gear 160 is transmitted to the wheels 300 through the half-shaft 400.

[0062] The powertrain 200 may include at least one of an engine and a drive motor. In some embodiments, the vehicle 1000 is a gasoline-powered vehicle, in which case the powertrain 200 includes an engine. In other embodiments, the vehicle 1000 is a new energy vehicle, specifically a pure electric vehicle, a range-extended electric vehicle, a plug-in hybrid electric vehicle, or a hybrid vehicle (not externally charged), etc. Other aspects of the vehicle 1000 not detailed herein can be found in relevant prior art disclosures and will not be elaborated here.

[0063] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0064] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0065] It should be noted that all directional indications in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0066] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0067] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0069] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0070] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A differential, characterized in that, include: Differential housing; The planetary shaft is connected to the differential housing; as well as Two planetary gears are provided, each with a shaft hole; the two planetary gears are respectively sleeved on both ends of the planetary shaft through the shaft hole to be rotatably connected to the planetary shaft; The outline of the shaft hole is a superelliptical drum-shaped line.

2. The differential according to claim 1, characterized in that, The equation for the hyperelliptical drum-shaped line is: ； Where a is the length of the shaft hole, b is the set drum shape coefficient, the exponent n is 2~5, x is the axial coordinate of the shaft hole contour line, and y is the radial coordinate of the shaft hole contour line.

3. The differential according to claim 2, characterized in that, The drum shape coefficient b is: b = (0.001~0.0015) * a.

4. The differential according to any one of claims 1-3, characterized in that, An oil reservoir is provided in the area on the planetary shaft that rotates with the planetary gear.

5. The differential according to claim 4, characterized in that, The length of the oil reservoir is the same as the length of the shaft hole; and / or, the width of the oil reservoir is 15% to 25% of the circumference of the planetary shaft.

6. The differential according to claim 4, characterized in that, The planetary shaft has a cross-section; the oil reservoir is formed by the cross-section and the stepped structures located at both ends of the cross-section along its axial direction.

7. The differential according to claim 6, characterized in that, The depth of the oil reservoir is 0.2mm to 0.8mm; and / or, the connection between the cut surface and the axial surface of the planetary shaft is provided with a transition fillet.

8. The differential according to any one of claims 1-3, characterized in that, The surface roughness Ra of the planetary shaft is 0.4μm~0.8μm.

9. The differential according to claim 8, characterized in that, The surface of the planetary shaft is provided with a nickel plating layer; the plating depth of the nickel plating layer is 0.01mm~0.03mm, and / or the hardness of the nickel plating layer is not less than 750HV0.

05.

10. A vehicle, characterized in that, The differential includes any one of claims 1-9.

Images