Planetary gear shaft and differential mechanism

Abstract

The utility model relates to the technical field of new energy automobile differential mechanisms, in particular to a planetary gear shaft and a differential mechanism, the planetary gear shaft comprises a planetary gear shaft base body, the planetary gear shaft base body is made of quenched and tempered alloy steel, and a diamond-like carbon layer covers the portion, where a planetary gear body is installed, of the planetary gear shaft base body. And it can be ensured that the planetary gear shaft base body has enough material toughness and strength. Meanwhile, by means of the characteristics of high hardness and low friction coefficient of the diamond-like layer, abrasion between the planetary gear shaft and the planetary gear can be effectively reduced, the diamond-like layer has good self-lubricating performance, meshing between the planetary gear shaft and the planetary gear can be effectively prevented, and therefore the service life of the differential mechanism is prolonged; the diamond-like carbon layer covers the outside of the planetary gear shaft base body for adjusting the alloy steel, so that generation and expansion of fatigue cracks of the planetary gear shaft can be inhibited, and the anti-fatigue performance of the planetary gear shaft is improved. The differential mechanism comprises a shell, and the planetary gear shaft is arranged in the shell in a penetrating mode.

Description

TECHNICAL FIELD

[0001] The utility model relates to new energy automobile differential mechanism technical field, concretely relates to a kind of planetary gear shaft and differential mechanism. BACKGROUND

[0002] Differential mechanism is the important component in automobile transmission system, its function is to realize the differential rotation of left and right drive wheels, ensure that vehicle can travel smoothly when turning. Planetary gear shaft as the key component in differential mechanism, its performance directly influences the service life and reliability of differential mechanism, can effectively prevent the problems such as planetary gear shaft cracking, shaft breakage and abnormal wear when torque load stress is too large and differential is too large during whole vehicle driving.

[0003] With the popularity of electric vehicles, users have higher and higher requirements on vehicle impact and durability, so that vehicle manufacturers also have higher and higher requirements on the service life of differential mechanism inside reduction gearbox. But the existing planetary gear shaft base material is 42CrMo, 4320H and other alloys, surface treatment QPQ ("Quench-Polish-Quench", namely "quenching-polishing-quenching") and gas nitriding, and the differential mechanism assembled exists the risk of planetary gear shaft fracture and ablation, poor surface wear resistance, and it is difficult to meet the market demand. SUMMARY

[0004] In view of the technical problem that the mechanical properties of existing planetary gear shafts are difficult to meet market demand, the utility model provides a planetary gear shaft and differential mechanism, which has high toughness, strength, and good wear resistance, fatigue resistance and anti-seizure performance, can prolong the service life of differential mechanism, to meet the market demand of new energy vehicles.

[0005] The utility model realizes the following technical scheme:

[0006] In the first aspect, the utility model provides a planetary gear shaft, which comprises a planetary gear shaft base body, the planetary gear shaft base body is a quenched and tempered alloy steel, and the part of the planetary gear shaft base body where the planetary gear body is installed is covered with a diamond-like carbon layer.

[0007] The planetary gear shaft provided by the utility model can have high toughness and strength, good wear resistance, fatigue resistance and anti-bite performance, and can prolong the service life of the differential mechanism, thereby meeting the market demand of new energy vehicles.

[0008] Therefore, the planetary gear shaft provided by the utility model has high toughness and strength, good wear resistance, fatigue resistance and anti-bite performance, and can prolong the service life of the differential mechanism, thereby meeting the market demand of new energy vehicles.

[0009] In an optional embodiment of the present application, the material of the planetary gear shaft body is 30CrNiMo8 alloy, so as to ensure that the planetary gear shaft body has sufficient toughness and strength, and also ensure that the planetary gear shaft body has low hardness after heat treatment, thereby effectively absorbing impact energy received during operation of the differential mechanism.

[0010] In an optional embodiment of the present application, the material heat treatment of the planetary gear shaft body is quenching and tempering treatment, so as to facilitate control of the surface hardness of the planetary gear shaft body.

[0011] In an optional embodiment of the present application, the hardness of the planetary gear shaft body after material heat treatment is 340-420 HV, so as to make the surface hardness of the planetary gear shaft body similar to the hardness of the differential mechanism housing.

[0012] In an optional embodiment of the present application, the diamond-like layer covers the outside of the planetary gear shaft body, and the two end portions of the planetary gear shaft body protrude from the diamond-like layer by 8-12 mm, which can reduce production and processing costs, facilitate clamping of the planetary gear shaft body during production, and make the hardness of the contact portion of the planetary gear shaft and the differential mechanism housing similar.

[0013] In an optional embodiment of the present application, the thickness of the diamond-like layer is 2.5-5 μm.

[0014] In an optional embodiment of the present application, the diamond-like layer is solidified on the surface of the planetary gear shaft body through physical vapor deposition or chemical vapor deposition, so as to ensure that the diamond-like layer has sufficient adhesion.

[0015] In an optional embodiment of the present application, the roughness of the planetary gear shaft base body is Rz < 1.6 μm, and the roughness of the diamond-like layer is Rz < 2 μm.

[0016] In a second aspect, the utility model provides a differential mechanism, including casing, the casing is equipped with above mentioned planetary gear shaft, to prolong the service life of differential mechanism, satisfy the market demand of new energy automobile.

[0017] In an optional embodiment of the present application, the planetary gear shaft base body is fixedly connected with the casing through elastic pins, to avoid relative movement of the planetary gear shaft relative to the differential mechanism casing.

[0018] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0019] 1. The planetary gear shaft provided by the utility model comprises a planetary gear shaft base body of a quenched and tempered alloy, which can ensure that the planetary gear shaft base body has sufficient material toughness and strength, and a diamond-like layer is covered on the part of the planetary gear shaft base body where the planetary gear body is installed, which can reduce the friction factor between the planetary gear and the planetary gear shaft, effectively reduce the wear between the planetary gear shaft and the planetary gear, effectively prevent the engagement between the planetary gear shaft and the planetary gear, thereby prolonging the service life of the differential mechanism, and on the other hand, the diamond-like layer is covered on the outside of the planetary gear shaft base body of the quenched and tempered alloy, which can inhibit the initiation and expansion of fatigue cracks of the planetary gear shaft and improve the fatigue resistance of the planetary gear shaft, so that the utility model can prolong the service life of the differential mechanism and meet the market demand of new energy vehicles.

[0020] 2. The differential mechanism provided by the utility model comprises a casing, and the casing is equipped with the planetary gear shaft, so as to prolong the service life of the differential mechanism and meet the market demand of new energy vehicles. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme of the embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the utility model, and should not be regarded as limiting the scope. For ordinary skilled in the art, under the premise of not paying creative labor, other related drawings can also be obtained according to these drawings.

[0022] In the drawings:

[0023] Figure 1 The structural schematic view of the planetary gear shaft provided by the embodiments of the present application is shown in the drawings.

[0024] Figure 2The differential structure schematic diagram provided by the embodiment of the present application.

[0025] The reference signs and corresponding component names in the drawings:

[0026] 1 - planetary gear shaft base, 2 - diamond-like layer, 3 - planetary gear body, 4 - housing, 5 - elastic pin, 6 - driven bevel gear, 7 - half shaft gear. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme of the embodiment of the present application will be described clearly and completely below in combination with the drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiment of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts are within the scope of protection of the present application.

[0029] It should be noted that: similar reference signs and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. The embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0030] In the description of the embodiments of the present application, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the application is used, or the orientation or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0031] In the description of the present application, unless otherwise explicitly specified and limited, the terms "set", "mount", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] Embodiment 1

[0033] Combining Figure 1 The embodiment provides a planetary gear shaft, which comprises a planetary gear shaft base body 1 made of a quenched and tempered alloy steel, and a diamond-like carbon layer 2 covering a part of the planetary gear shaft base body 1 where a planetary gear body is installed.

[0034] It can be understood that the quenched and tempered alloy steel refers to a medium-carbon steel quenched and tempered alloy steel with a carbon content of 0.3-0.6%. The most widely used quenched and tempered steel includes a chromium quenched and tempered steel (such as 40Cr, 40CrSi), a chromium-manganese quenched and tempered steel (such as 40CrMn, 42CrMo), a chromium-nickel quenched and tempered steel (such as 40CrNiMo, 37CrNi3A), a boron-containing quenched and tempered steel, and the like.

[0035] In the embodiment, the material of the planetary gear shaft base body 1 is 30CrNiMo8 alloy, so as to ensure that the planetary gear shaft base body 1 has sufficient toughness and strength, and at the same time, ensure that the planetary gear shaft base body 1 has a relatively low hardness after heat treatment, so as to effectively absorb the impact energy received during the operation of the differential.

[0036] Correspondingly, the material heat treatment of the planetary gear shaft base body 1 is quenching and high-temperature tempering, so as to facilitate the control of the surface hardness of the planetary gear shaft base body 1.

[0037] In the embodiment, the hardness of the planetary gear shaft base body 1 after the material heat treatment is 340-420HV, so as to make the surface hardness of the planetary gear shaft base body 1 close to the hardness of the differential housing 4.

[0038] It should be understood that the material of the diamond-like carbon layer 2 includes Cr, CrN and a-C:H, which is usually solidified on the surface of the planetary gear shaft base body 1 through physical vapor deposition or chemical vapor deposition, so as to ensure that the diamond-like carbon layer 2 has sufficient adhesion.

[0039] The adhesion of the coating is ≤HF4.

[0040] In the embodiment, the diamond-like carbon layer 2 covers the outside of the planetary gear shaft base body 1, and the two ends of the planetary gear shaft base body 1 protrude from the diamond-like carbon layer 2 by 28-12mm, which can reduce the production and processing cost, facilitate the clamping of the planetary gear shaft base body 1 during the production process, and make the hardness of the contact part of the planetary gear shaft and the differential housing 4 close.

[0041] Further, the thickness of the diamond-like carbon layer 2 is 2.5-5μm, the roughness of the planetary gear shaft base body 1 is Rz<1.6μm, and the roughness of the diamond-like carbon layer 2 is Rz<2μm. Finally, the friction coefficient of the diamond-like carbon layer 2 is less than 0.12, and the hardness is >2000HV.

[0042] The specific processing method is as follows: after the planetary gear shaft base body 1 is cleaned and quenched and tempered, a DLC coating (diamond-like carbon layer 2) is deposited on the surface of the planetary gear shaft base body 1 by physical vapor deposition (PVD) or chemical vapor deposition (CVD) process, and finally the planetary gear shaft with the DLC coating is post-treated, such as polishing, cleaning, etc.

[0043] In summary, the planetary gear shaft provided by the embodiment comprises a planetary gear shaft base body 1 made of quenched and tempered alloy, and a diamond-like carbon layer 2 covering the part of the planetary gear shaft base body 1 where the planetary gear body is installed.

[0044] Therefore, on the one hand, the diamond-like carbon layer 2 has high hardness and low friction coefficient, which can reduce the friction coefficient between the planetary gear and the planetary gear shaft, effectively reduce the wear between the planetary gear shaft and the planetary gear, and has good self-lubricating property, which can effectively prevent the engagement between the planetary gear shaft and the planetary gear, thereby prolonging the service life of the differential.

[0045] In addition, the coating process of the diamond-like carbon layer 2 is mature, easy to implement, and relatively low in cost.

[0046] In summary, the planetary gear shaft provided by the embodiment has high toughness, strength, and good wear resistance, fatigue resistance and anti-engagement performance, can prolong the service life of the differential, and meet the market demand of new energy vehicles.

[0047] Embodiment 2

[0048] In combination Figure 2 The embodiment provides a differential, which comprises a housing 4, and the planetary gear shaft described above is arranged in the housing 4, so as to prolong the service life of the differential and meet the market demand of new energy vehicles.

[0049] In the embodiment, the planetary gear shaft base body 1 is fixedly connected with the housing 4 through the elastic pin 5, so as to avoid the relative movement of the planetary gear shaft relative to the differential housing 4.

[0050] Specifically, for the new energy vehicle, the differential mechanism comprises: a driven bevel gear 6 fixedly installed outside the housing 4, so as to drive the whole differential to rotate under the rotation of the driven bevel gear 6; a planetary gear body 3 installed at the corresponding end of the planetary gear shaft; and a half shaft gear 7 installed on both sides in the housing 4.

[0051] When working, the input torque of the main reduction gear is transmitted to the differential housing 4, and the housing 4 is fixedly connected with the planetary gear shaft, and finally is applied to the planetary gear shaft. When the automobile is driving straight, the planetary gear shaft needs to drive the planetary gear to revolve, and transmit the torque to the two side wheels. At this time, the planetary gear shaft bears the torque load from the main reducer, and ensures that the left and right wheels rotate at the same speed. When turning, the planetary gear revolves on the basis of superimposing the rotation, which causes the planetary gear shaft to balance the speed difference of the two side wheels, and bears the shear force and the torsion force. At this time, the stress is more complex, including the radial force and the axial force generated by the gear meshing.

[0052] It should be explained that the planetary gear shaft and the differential mentioned above can be used in new energy vehicles, fuel vehicles and other mechanical transmission mechanisms requiring similar differential structures.

[0053] The above specific embodiments further specifically explain the purpose, technical scheme and beneficial effects of the present application, and it should be understood that the above is only a specific embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A planetary gear shaft, characterized in that The planetary gear shaft base (1) is made of a quenched and tempered alloy steel, and the part of the planetary gear shaft base (1) where the planetary gear body is installed is covered with a diamond-like carbon layer (2).

2. The planetary gear shaft of claim 1, wherein, The material of the planetary gear shaft base (1) is 30CrNiMo8 alloy.

3. The planetary gear shaft of claim 2, wherein, The material heat treatment of the planetary gear shaft base (1) is quenching and tempering.

4. The planetary gear shaft of claim 3, wherein, The hardness of the planetary gear shaft base (1) after material heat treatment is 340-420 HV.

5. The planetary gear shaft of claim 1, wherein, The diamond-like carbon layer (2) is covered on the outer surface of the planetary gear shaft base (1), and the two ends of the planetary gear shaft base (1) protrude from the diamond-like carbon layer (2) by 8-12 mm.

6. The planetary gear shaft of claim 1, wherein, The thickness of the diamond-like carbon layer (2) is 2.5-5 μm.

7. The planetary gear shaft according to any one of claims 1 to 6, characterized in that The diamond-like carbon layer (2) is solidified on the surface of the planetary gear shaft base (1) by physical vapor deposition or chemical vapor deposition.

8. The planetary gear shaft according to any one of claims 1 to 6, characterized in that The roughness of the planetary gear shaft base (1) is Rz<1.6 μm, and the roughness of the diamond-like carbon layer (2) is Rz<2 μm.

9. A differential characterized by, The planetary gear shaft base (1) is fixedly connected with the shell (4) through elastic pins (5).

10. The differential of claim 9, wherein, The planetary gear shaft base (1) is fixedly connected with the shell (4) through elastic pins (5).

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