Low-friction planetary reducer axial limiting structure

Abstract

The present application relates to the technical field of planetary reducer, and discloses a low-friction axial limiting structure of planetary reducer, which comprises a reducer, an axial limiting mechanism, a sun gear, a memory alloy compensation ring and a hydraulic compensation ring. The axial limiting mechanism is arranged on the side of the sun gear facing the second planetary gear, and the memory alloy compensation ring is arranged on the step position of the sun gear. The memory alloy compensation ring can compensate the thermal gap by the thermal expansion of the shape memory alloy under the action of temperature, and the hydraulic compensation ring can drive the compensation member by introducing the oil pressure through the hydraulic compensation pipe to assist the flexible compensation. Therefore, the axial displacement of the sun gear and the sun gear of the rotating frame is always constrained within the design threshold of low friction during the operation of the reducer in the full temperature range.

Description

Technical Field

[0001] This invention relates to the field of planetary gear reducer technology, and in particular to a low-friction planetary gear reducer axial limiting structure. Background Technology

[0002] As a core transmission component of the electric drive system of new energy vehicles, planetary gearboxes play a crucial role in converting the high-speed, low-torque power of the drive motor into the low-speed, high-torque power required by the wheels. Compared with traditional industrial gearboxes, the working conditions of planetary gearboxes in new energy vehicles are more stringent.

[0003] In the actual operation of planetary reducers for new energy vehicles, the wide-range speed regulation characteristics of the drive motor cause the internal temperature field of the reducer to fluctuate dramatically. During the cold start-up phase, especially in the frigid winter environment of northern China, the reducer housing and internal gear system are both in a low-temperature environment, causing metal components to shrink and the axial assembly clearance to reach its maximum value. When the vehicle is continuously cruising at high speed or frequently accelerating and decelerating, the combined effects of gear meshing friction heat, bearing rolling friction heat, and lubricating oil churning shear heat cause the internal temperature of the reducer to rise rapidly to over 100°C. Due to the significant difference in the linear expansion coefficients between the aluminum alloy housing and the alloy steel gear materials, the difference in axial thermal expansion between the housing and the internal transmission shaft system under hot conditions can reach 0.1mm to 0.3mm. This seemingly small dimensional change is sufficient to cause a drastic change in the contact state of the limiting end face for a precision planetary reducer with an axial limiting clearance of only 0.02mm to 0.05mm.

[0004] To address the aforementioned issues, existing technologies (CN211315051U) disclose an axial positioning structure for the bearing at the inlet of a planetary reducer, which achieves axial positioning of the bearing by setting an inner protrusion and an adjusting shim on the end face where the front flange intersects with the bearing hole; and existing technologies (CN203130997U) disclose an axial clearance adjustment structure for a planetary reducer, which achieves clearance adjustment without disassembly by adjusting the screw and the threaded engagement of the end cover. These rigid limiting schemes cannot adapt to the thermal deformation differences caused by temperature changes. If the cold clearance is reserved according to the thermal expansion, the axial constraint is insufficient under normal and low temperature conditions, leading to gear axial movement, resulting in meshing imbalance and increased vibration noise. If the cold clearance is set according to the optimal value at normal temperature, the limiting shim and the gear end face will experience rigid interference compression under high temperature conditions. For example, the X-type standard planetary gear reducer with automatic axial clearance compensation function disclosed in the prior art (CN103322131A) releases elastic force to compensate for the clearance by setting an elastic element between the second sun gear and the planet gear carrier; and the prior art (CN210859771U) discloses a coaxial planetary gear reducer with housing cooling, which applies axial preload to the input bevel gear through a wave washer; for this type of elastic preload limiting method, the contradiction between thermal expansion and clearance control is alleviated to a certain extent, but its stiffness characteristics are difficult to adaptively match the nonlinear axial force requirements across the entire temperature range.

[0005] Therefore, there is an urgent need to develop a low-friction planetary reducer axial limiting structure that can intelligently sense temperature changes and actively adjust axial constraint force, in order to meet the urgent needs of the new energy vehicle industry for high efficiency, long life and high reliability of core transmission components. Summary of the Invention

[0006] The purpose of this invention is to provide a low-friction planetary reducer axial limiting structure. Through the axial limiting mechanism, a non-tooth cylindrical step is provided on the side of the sun gear facing the second planet gear, and a compensation ring assembly is installed at this step position. The compensation ring assembly can compensate for the hot gap by utilizing the thermal expansion characteristics of shape memory alloys under temperature. In conjunction with a hydraulic compensation ring, oil pressure is introduced through a hydraulic supply pipe to drive the compensation component for auxiliary flexible compensation. This ensures that during the reducer's operation across the entire temperature range, the axial movement between the sun gear and the sun gear on the carrier is always constrained within the design threshold of extremely low friction, thus solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a low-friction planetary reducer axial limiting structure, including a reducer, an axial limiting mechanism installed inside the reducer, and a compensation ring assembly arranged between the axial limiting mechanisms, a lubrication assembly arranged above the reducer, and a cooling assembly arranged below the reducer. The axial limiting mechanism includes a sun gear rotatably installed inside the reducer, and three sets of first planetary gears are meshed on the outer side of the sun gear. The rear end of the first planetary gear is connected to a carrier sun gear, and three sets of second planetary gears are meshed on the outer side of the carrier sun gear. The compensation ring assembly includes a shape memory alloy compensation ring installed at the front end of the sun gear and at the step position of the sun gear on the rotating frame. A thin film heating element is provided on one side of the shape memory alloy compensation ring, and a hydraulic compensation ring is provided on the other side of the shape memory alloy compensation ring. The cooling component includes a semiconductor cooling chip embedded in the inner wall of the speed reducer.

[0008] Preferably, the axial limiting mechanism further includes a first gear ring meshing with the outside of the first planetary gear, a second gear ring meshing with the outside of the second planetary gear, and an output wheel connected to the rear end of the second planetary gear.

[0009] Preferably, a connecting shaft is provided between one of the first planetary gears and the sun gear of the carrier, and a connecting shaft is also provided between one of the second planetary gears and the output gear. A non-toothed cylindrical step is provided on the side of the sun gear of the carrier facing the second planetary gear, and a compensation ring assembly is installed on the non-toothed cylindrical step.

[0010] Preferably, a heat-conducting ring is provided between the semiconductor cooling chip and the first and second gear rings, the cooling end of the semiconductor cooling chip is in close contact with the heat-conducting ring, and a cooling fan is provided on the lower side of the heating end of the semiconductor cooling chip. A bottom support is provided on the outside of the cooling fan, and a dust cover is installed at the end of the bottom support.

[0011] Preferably, the reducer includes a housing, an end cover is installed at the front end of the housing, and locking screws are embedded around the connection between the end cover and the housing. An input shaft is provided at the center of the front end of the end cover, and an output shaft is provided at the center of the rear end of the housing. Oil seals are provided on the outside of the output shaft and the input shaft.

[0012] Preferably, a temperature sensor is embedded inside the end cap, and a controller is provided below the temperature sensor. A bearing is provided at the connection between the end cap and the sun gear.

[0013] Preferably, the lubrication assembly includes a lubricating oil tank fixed above the housing, the front end of the lubricating oil tank is connected to an accumulator via a pipe, and the front end of the accumulator is connected to a proportional valve via a pipe.

[0014] Preferably, the output end of the proportional valve is connected to two hydraulic supply pipes and one lubricating oil output pipe, with the output end of the lubricating oil output pipe facing the sun gear of the rotating frame.

[0015] Preferably, the hydraulic compensation ring has a T-shaped compensation component that is slidably disposed inside, and the hydraulic compensation ring is connected to the hydraulic supply pipe.

[0016] Preferably, the bottom of the housing is provided with a connecting groove, the bottom bracket surrounds the outside of the connecting groove, and the accumulator and the proportional valve are provided with a protective frame fixed on the top of the housing.

[0017] Compared with the prior art, the beneficial effects of the present invention are: By setting an axial limiting mechanism, a non-tooth cylindrical step is provided on the side of the sun gear of the rotating frame facing the second planet gear, and the compensation ring assembly is installed at the step position. Compared with the large-area planar contact of the traditional shaft shoulder end face, the contact form of the axial limiting friction pair is changed from continuous friction of the entire circumferential end face to local intermittent contact of a small-diameter circumferential surface. This significantly reduces the equivalent friction radius and contact area of ​​the limiting mechanism, reduces the parasitic friction torque caused by axial constraint, and since the non-tooth cylindrical step rotates synchronously with the sun gear of the rotating frame, the shape memory alloy compensation ring and the hydraulic compensation ring in the compensation ring assembly only contact the step surface at a specific phase of the rotation cycle, forming an intermittent limiting effect of meshing in and meshing out. By setting up a compensation ring assembly, the thermal gap can be compensated by utilizing the thermal expansion characteristics of shape memory alloy under temperature action. In conjunction with the hydraulic compensation ring, oil pressure is introduced through the hydraulic supply pipe to drive the compensation component for auxiliary flexible compensation, so that the axial movement of the sun gear and the slewing sun gear is always constrained within the design threshold of extremely low friction during the operation of the reducer in the entire temperature range. By setting up a cooling component, the semiconductor cooling chip directly applies the cooling energy to the outer surfaces of the first and second gear rings through the heat conduction ring. Since the gear ring is the main accumulation body of gear meshing heat, direct cooling of it can effectively suppress the temperature difference amplitude between the outer shell and the internal gear system, thereby reducing the absolute amount of axial thermal expansion from the heat source end, reducing the compensation stroke requirement of the compensation ring assembly, and extending the fatigue life of the shape memory alloy compensation ring. Through the lubrication assembly, the compensation component inside the hydraulic compensation ring is connected to the hydraulic supply pipe. The oil pressure of the lubrication system is used as the power source to drive the compensation ring assembly. There is no need to set up an additional independent hydraulic power source. The lubricating oil output pipe is directly facing the area where the sun gear of the rotating frame is located. The lubricating oil can flow along the sun gear of the rotating frame through the meshing surface of the second planetary gear and the sun gear of the rotating frame to achieve lubrication. With the set reducer, the housing has an embedded temperature sensor and controller. When the temperature sensor detects a change in the internal temperature of the housing, the controller can dynamically adjust the energizing state of the thin film heating element and the opening area of ​​the proportional valve according to the preset logic, so that the axial limiting force is accurately matched with the real-time thermal load, avoiding the extra frictional power consumption caused by overcompensation. By organically combining non-tooth cylindrical steps, shape memory alloy compensation rings, semiconductor cooling chips, and lubrication systems, the traditional large-area continuous sliding friction of axial limiting is transformed into small-radius intermittent low-friction constraint without increasing the radial dimension of the reducer used in new energy vehicles. This effectively reduces the no-load starting torque of the reducer and the ineffective heat loss during high-speed operation, significantly improving the mechanical transmission efficiency and thermal stability of the reducer in new energy vehicles, making it particularly suitable for precision transmission applications in new energy vehicles. Attached Figure Description

[0018] Figure 1 This is an overall structural view of the present invention; Figure 2 This is a bottom-view structural diagram of the present invention; Figure 3 This is a cross-sectional structural diagram of the present invention; Figure 4 This is a schematic diagram of the cross-sectional structure of the present invention; Figure 5 This is a schematic diagram of the axial limiting mechanism of the present invention; Figure 6 This is a schematic diagram of the cross-sectional structure of the sun gear of the rotating frame of the present invention; Figure 7 For the present invention Figure 3 A magnified structural diagram at point A; Figure 8 This is a schematic diagram of the structure of the compensation ring assembly of the present invention; Figure 9 This is a partial structural schematic diagram of the heat-conducting ring of the present invention.

[0019] Figure label: 1. Reducer; 101. Housing; 102. End cover; 103. Input shaft; 104. Oil seal; 105. Output shaft; 106. Locking screw; 107. Connecting groove; 108. Temperature sensor; 109. Controller; 2. Axial limiting mechanism; 201. Sun gear; 202. First planetary gear; 203. First gear ring; 204. Carrier sun gear; 205. Second planetary gear; 206. Second gear ring; 207. Output gear; 208. Bearing; 209. Connector 3. Shaft; 4. Cooling assembly; 5. Bottom bracket; 6. Cooling fan; 7. Dust cover; 8. Heat conduction ring; 9. Semiconductor cooling chip; 10. Lubrication assembly; 11. Lubricating oil tank; 2. Protective frame; 303. Hydraulic supply pipe; 404. Lubricating oil output pipe; 5. Accumulator; 6. Proportional valve; 7. Compensation ring assembly; 12. Shape memory alloy compensation ring; 23. Thin film heating element; 34. Hydraulic compensation ring; 55. Compensating component. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 , Figure 3 , Figure 5 , Figure 6 and Figure 8 The present invention provides a low-friction planetary reducer axial limiting structure, including a reducer 1, an axial limiting mechanism 2 installed inside the reducer 1, a compensation ring assembly 5 between the axial limiting mechanisms 2, a lubrication assembly 4 above the reducer 1, and a cooling assembly 3 below the reducer 1. The axial limiting mechanism 2 includes a sun gear 201 rotatably installed inside the reducer 1, and three sets of first planet gears 202 are meshed on the outer side of the sun gear 201. The rear end of the first planet gear 202 is connected to a rotating carrier sun gear 204, and three sets of second planet gears 205 are meshed on the outer side of the rotating carrier sun gear 204. The compensation ring assembly 5 includes a shape memory alloy compensation ring 501 installed at the front end of the sun gear 201 and at the step position of the sun gear 204 of the rotating frame. A thin film heating element 502 is provided on one side of the shape memory alloy compensation ring 501, and a hydraulic compensation ring 503 is provided on the other side of the shape memory alloy compensation ring 501. The cooling component 3 includes a semiconductor cooling chip 305 embedded in the inner wall of the reducer 1.

[0022] The axial limiting mechanism 2 also includes a first gear ring 203 meshing with the outside of the first planetary gear 202, a second gear ring 206 meshing with the outside of the second planetary gear 205, an output gear 207 connected to the rear end of the second planetary gear 205, a connecting shaft 209 between one of the first planetary gears 202 and the carrier sun gear 204, and a connecting shaft 209 between one of the second planetary gears 205 and the output gear 207. The carrier sun gear 204 has a non-tooth cylindrical step on the side facing the second planetary gear 205, and one of the compensation ring assemblies 5 is installed on the non-tooth cylindrical step. A thin-walled cylindrical guide bushing is required at the root of the non-tooth cylindrical step of the carrier sun gear 204 to axially guide the shape memory alloy compensation ring 501.

[0023] By adopting the above technical solution, after the reducer 1 is powered on, the external torque is transmitted to the sun gear 201 through the input shaft 103. The sun gear 201 drives the three sets of first planetary gears 202 to rotate through gear meshing. The first planetary gears 202 perform planetary motion under the constraint of the internal teeth of the first gear ring 203. Their power is transferred to the rear-end rotating sun gear 204 through the connecting shaft 209. The rotating sun gear 204 then acts as the driving element of the second stage of transmission, driving the three sets of second planetary gears 205 to mesh and rotate in the second gear ring 206. Finally, the amplified torque is transmitted from the output wheel 207 to the output shaft 105 through the connecting shaft 209.

[0024] By using the axial limiting mechanism 2, a non-toothed cylindrical step is provided on the side of the sun gear 204 facing the second planetary gear 205, and the compensation ring assembly 5 is installed at the step position. Compared with the large-area planar contact of the traditional shaft shoulder end face, the contact form of the axial limiting friction pair is changed from continuous friction of the entire circumferential end face to local intermittent contact of a small-diameter circumferential surface. This significantly reduces the equivalent friction radius and contact area of ​​the limiting mechanism, reduces the parasitic friction torque generated by axial constraint, and since the non-toothed cylindrical step rotates synchronously with the sun gear 204, the shape memory alloy compensation ring 501 and the hydraulic compensation ring 503 in the compensation ring assembly 5 only contact the step surface at a specific phase of the rotation cycle, forming an intermittent limiting effect of meshing and meshing out.

[0025] By using the compensation ring assembly 5, the thermal gap can be compensated by utilizing the thermal expansion characteristics of the shape memory alloy under temperature. In conjunction with the hydraulic compensation ring 503, the hydraulic supply pipe 403 introduces oil pressure to drive the compensation component 504 for auxiliary flexible compensation. This ensures that the axial movement of the sun gear 201 and the slewing sun gear 204 is always constrained within the design threshold of extremely low friction during the operation of the reducer 1 in the entire temperature range.

[0026] Specifically, such as Figure 2 , Figure 3 , Figure 7 and Figure 9 As shown, a heat-conducting ring 304 is provided between the thermoelectric cooler 305 and the first gear ring 203 and the second gear ring 206. The contact surfaces of the heat-conducting ring 304 with the thermoelectric cooler 305, the first gear ring 203 and the second gear ring 206 are coated with high thermal conductivity silicone grease to reduce the interfacial thermal resistance. The cooling end of the thermoelectric cooler 305 is in close contact with the heat-conducting ring 304, and a cooling fan 302 is provided on the lower side of the heating end of the thermoelectric cooler 305. A bottom support 301 is provided on the outside of the cooling fan 302, and a dust cover 303 is installed at the end of the bottom support 301. The heating end of the thermoelectric cooler 305 needs to be brazed with heat dissipation fins to increase the heat exchange area with the forced airflow. In addition, heat insulation material is added to the outside of the thermoelectric cooler 305 to prevent the heat generated by the cooling end of the thermoelectric cooler 305 from being transferred in the housing of the reducer 1, thus ensuring the cooling efficiency.

[0027] By adopting the above technical solution, the semiconductor cooling chip 305 is an existing cooling device based on the thermoelectric effect principle of semiconductor materials. It is mainly composed of two materials: N-type semiconductor and P-type semiconductor. These two materials are connected by a metal wire to form a thermocouple. When current passes through the thermocouple, heat flows from one end to the other due to the thermoelectric effect, thereby achieving a cooling effect. When the semiconductor cooling chip 305 is working, electrons on one side transition from a low energy level to a high energy level, absorbing heat and lowering the temperature, which is called the cooling end; electrons on the other side transition from a high energy level to a low energy level, releasing heat and raising the temperature, which is called the heating end. If the heating end cannot dissipate heat in time, the heat in the heating end will be lost. The accumulation of heat affects the normal operation of the thermoelectric cooler 305. When the thermoelectric cooler 305 is in use, the cooling fan 302 draws in external cold air and flows through the heating end of the thermoelectric cooler 305. After carrying heat, it is discharged through the dust cover 303. The cooling end of the thermoelectric cooler 305 is in close contact with the heat-conducting ring 304. The cold energy is efficiently transferred to the outer wall of the first gear ring 203 and the second gear ring 206 through the heat-conducting ring 304. The reduction in the temperature of the gear ring directly inhibits the accumulation of heat in the gear meshing, thereby reducing the absolute value of the axial thermal expansion of the sun gear 204 and the output gear 207 from the source. This reduces the compensation burden of the compensation ring assembly 5 and maintains the basic thermal environment for low-friction operation.

[0028] Through the cooling component 3, the semiconductor cooling chip 305 directly applies cooling energy to the outer surfaces of the first gear ring 203 and the second gear ring 206 via the heat-conducting ring 304. Since the gear ring is the main storage body for gear meshing heat, direct cooling of it can effectively suppress the temperature difference amplitude between the outer shell 101 and the internal gear system, thereby reducing the absolute amount of axial thermal expansion from the heat source end, reducing the compensation stroke requirement of the compensation ring component 5, and extending the fatigue life of the shape memory alloy compensation ring 501.

[0029] Specifically, such as Figures 1 to 4 As shown, the reducer 1 includes a housing 101. An end cover 102 is installed at the front end of the housing 101, and locking screws 106 are embedded around the connection between the end cover 102 and the housing 101. The housing 101 and the end cover 102 form a closed cavity through the locking screws 106. An input shaft 103 is provided at the middle of the front end of the end cover 102, and an output shaft 105 is provided at the middle of the rear end of the housing 101. An oil seal 104 is provided on the outside of the output shaft 105 and the input shaft 103. During the entire rotation process, the input shaft... The oil seal 104 outside the output shaft 105 ensures absolute isolation between the internal and external environments of the reducer 1. The end cover 102 is equipped with a temperature sensor 108, and a controller 109 is provided below the temperature sensor 108. A bearing 208 is provided at the connection between the end cover 102 and the sun gear 201. The temperature sensor 108 is embedded inside the end cover 102. A heat-conducting copper sleeve needs to be added between its temperature sensing head and the metal hole wall of the end cover 102 to ensure that the temperature sensor 108 responds quickly to the temperature inside the housing.

[0030] By adopting the above technical solution, as the first gear ring 203 and the second gear ring 206 generate a large amount of frictional heat in the meshing area with the corresponding planetary gears, the internal temperature of the housing 101 rises. The temperature sensor 108 embedded in the end cover 102 monitors the temperature change in real time and transmits the signal to the controller 109. When the temperature exceeds the preset first threshold, the thermal expansion of the metal components inside the reducer 1 has begun to erode the preset axial safety clearance. The controller 109 turns on the power supply of the thin film heating element 502. The thin film heating element 502 is in close contact with the shape memory alloy compensation ring 501 and Joule heating is applied to it. After the shape memory alloy compensation ring 501 is heated to the austenitic phase transformation temperature, it undergoes directional expansion deformation along the axial direction, accurately compensating for the axial clearance expansion caused by the temperature difference between the housing 101 and the internal rotating sun gear 204.

[0031] With the speed reducer 1, which is equipped with an embedded temperature sensor 108 and a controller 109, when the temperature sensor 108 detects a change in the internal temperature of the housing 101, the controller 109 can dynamically adjust the energizing state of the thin film heating element 502 and the opening area of ​​the proportional valve 406 according to a preset logic, so that the axial limiting force is accurately matched with the real-time thermal load, avoiding the extra frictional power consumption caused by overcompensation.

[0032] Specifically, such as Figure 3 , Figure 5 and Figure 8 As shown, the lubrication assembly 4 includes a lubricating oil tank 401 fixed above the housing 101. The front end of the lubricating oil tank 401 is connected to an accumulator 405 via a pipe, and the front end of the accumulator 405 is connected to a proportional valve 406 via a pipe. The output end of the proportional valve 406 is connected to two hydraulic supply pipes 403 and a lubricating oil output pipe 404. The output end of the lubricating oil output pipe 404 faces the sun gear 204 of the rotating frame. The lubrication assembly 4 also integrates oil return components such as an oil return filter, an oil return pipe, a micro oil pump, and a safety valve. The oil return components are conventional mechanisms and will not be described in detail here. The oil return filter is used to remove wear particles. The micro oil pump pressurizes the accumulator 405 and maintains the system's working oil pressure, and provides oil return power.

[0033] The hydraulic compensation ring 503 has a T-shaped compensation component 504 that slides inside it, and the hydraulic compensation ring 503 is connected to the hydraulic supply pipe 403. The bottom of the outer shell 101 has a connecting groove 107, and the bottom bracket 301 surrounds the outside of the connecting groove 107. The accumulator 405 and the proportional valve 406 are provided with a protective frame 402 fixed on the top of the outer shell 101. By organically combining the non-tooth cylindrical step, the shape memory alloy compensation ring 501, the semiconductor cooling chip 305 and the lubrication system, the large-area continuous sliding friction of the traditional axial limit is transformed into a small-radius intermittent low-friction constraint without increasing the radial dimension of the reducer 1 used in new energy vehicles. This effectively reduces the no-load starting torque of the reducer 1 and the ineffective heat loss during high-speed operation, and significantly improves the mechanical transmission efficiency and thermal stability of the reducer 1 of new energy vehicles over a long period of time. It is especially suitable for precision transmission applications in new energy vehicles.

[0034] By adopting the above technical solution, hydraulic oil enters the hydraulic supply pipe 403 through one branch of the proportional valve 406 and is injected into the inner cavity of the hydraulic compensation ring 503. Under the push of oil pressure, the T-shaped compensation component 504 extends outward to compensate for the slight lag in the response speed of the shape memory alloy compensation ring 501 and to share the axial impact load under heavy load conditions, ensuring the reliability of the limit while avoiding rigid impact. Since the other branch of the proportional valve 406 delivers pressurized lubricating oil to the lubricating oil output pipe 404, the outlet of the lubricating oil output pipe 404 is precisely aligned with the sun gear 204 of the rotating frame. Through the set lubrication component 4, the compensation component 504 inside the hydraulic compensation ring 503 is connected to the hydraulic supply pipe 403. The oil pressure of the lubrication system is used as a power source to drive the compensation ring component 5. There is no need to set up an additional independent hydraulic power source. The lubricating oil output pipe 404 is directly facing the area where the sun gear 204 of the rotating frame is located. The lubricating oil can flow along the sun gear 204 of the rotating frame through the meshing surface of the second planetary gear 205 and the sun gear 204 of the rotating frame to achieve lubrication.

[0035] Working Principle: During the initial start-up and low-temperature operation phases, the internal metal components of the reducer 1 have not yet undergone significant thermal expansion. At this time, the two sets of compensation ring assemblies 5 are in their initial state. The shape memory alloy compensation ring 501 remains in a low-temperature contracted state, and the T-shaped compensation element 504 in the inner cavity of the hydraulic compensation ring 503 remains retracted under no or low pressure. The compensation ring assembly 5 provides a small axial floating safety clearance for each rotating component, ensuring that there is no forced contact pressure between the end face of the sun gear 201 and the end face of the bearing 208, and between the stepped surface of the sun gear 204 of the carrier and the limiting reference surface. The axial additional friction torque at the moment of start-up is extremely low, allowing the reducer 1 to operate at high speed. Once the response speed enters the normal meshing state, after the reducer 1 is powered on, the external torque is transmitted to the sun gear 201 through the input shaft 103. The sun gear 201 drives the three sets of first planetary gears 202 to rotate through gear meshing. The first planetary gears 202 perform planetary motion under the constraint of the internal teeth of the first gear ring 203. Their power is transferred to the rear frame sun gear 204 through the connecting shaft 209. The frame sun gear 204 then acts as the driving element of the second stage of transmission, driving the three sets of second planetary gears 205 to mesh and rotate within the second gear ring 206. Finally, the amplified torque is transmitted from the output wheel 207 to the output shaft 105 through the connecting shaft 209. As the first gear ring 203 and the second gear ring 206 generate a large amount of frictional heat in the meshing area with the corresponding planetary gears, the internal temperature of the housing 101 rises. The temperature sensor 108 embedded in the end cover 102 monitors the temperature change in real time and transmits the signal to the controller 109. When the temperature exceeds the preset first threshold, the thermal expansion of the metal components inside the reducer 1 has begun to erode the preset axial safety clearance. The controller 109 turns on the power of the thin film heating element 502. The thin film heating element 502 is in close contact with the shape memory alloy compensation ring 501 and applies Joule heating to it. After the shape memory alloy compensation ring 501 is heated to the austenitic phase transformation temperature, it undergoes directional expansion deformation along the axial direction, accurately compensating for the axial clearance expansion caused by the temperature difference between the housing 101 and the internal rotating sun gear 204. Since the compensation ring assembly 5 acts on the small diameter non-tooth cylindrical step rather than the large area of ​​the gear end face, even if the shape memory alloy compensation ring 501 applies axial constraint force, the frictional torque it generates is reduced to the minimum due to the significant reduction in the contact radius. Simultaneously, the controller 109 controls the opening of the proportional valve 406, the accumulator 405 provides a stable pressure source, and the hydraulic oil enters the hydraulic supply pipe 403 through one branch of the proportional valve 406 and is injected into the inner cavity of the hydraulic compensation ring 503. Under the push of the oil pressure, the T-shaped compensation component 504 extends outward to compensate for the slight lag in the response speed of the shape memory alloy compensation ring 501 and to share the axial impact load under heavy load conditions, ensuring the reliability of the limit while avoiding rigid impact. Since the other branch of the proportional valve 406 delivers the pressure lubricating oil to the lubricating oil output pipe 404, the outlet of the lubricating oil output pipe 404 is precisely aligned with the sun gear 204 of the rotating frame. The lubricating oil can periodically fill the small gaps in the contact area, greatly reducing the friction coefficient between the shape memory alloy compensation ring 501 and the step surface at the moment of contact, making the axial limit process close to pure rolling or wear-free sliding constraint. Controller 109 synchronously starts cooling fan 302. External cold air is drawn in and flows through the heating end of semiconductor cooling chip 305. After carrying heat, it is discharged through dust cover 303. The cooling end of semiconductor cooling chip 305 is in close contact with heat-conducting ring 304. The cooling energy is efficiently transferred to the outer wall of first gear ring 203 and second gear ring 206 through heat-conducting ring 304. The reduction in gear ring temperature directly inhibits the accumulation of heat in gear meshing, reducing the absolute value of axial thermal expansion of sun gear 204 and output gear 207 from the source, thereby reducing the compensation burden of compensation ring assembly 5 and maintaining the basic thermal environment for low-friction operation. When reducer 1 stops running or When the load decreases significantly and the internal temperature of the housing 101 drops below the second threshold, the temperature sensor 108 feeds back the low temperature signal to the controller 109. The controller 109 then cuts off the power supply to the thin film heating element 502. The shape memory alloy compensation ring 501 shrinks and retracts as the temperature drops due to the martensitic phase transformation. At the same time, the corresponding channel of the proportional valve 406 is closed. The compensation element 504 in the hydraulic compensation ring 503 resets under the action of end face thrust and its own elasticity. At this time, the sun gear 201 and the rotating frame sun gear 204 regain the initial micro-gap movement space, and the reducer 1 returns to the low friction standby state, ready for the next high-efficiency operation.

[0036] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A low-friction planetary reducer axial limiting structure, comprising a reducer (1), characterized in that: An axial limiting mechanism (2) is installed inside the reducer (1), and a compensation ring assembly (5) is provided between the axial limiting mechanisms (2). A lubrication assembly (4) is provided above the reducer (1), and a cooling assembly (3) is provided below the reducer (1). The axial limiting mechanism (2) includes a sun gear (201) rotatably installed inside the reducer (1), and three sets of first planet gears (202) are meshed on the outer side of the sun gear (201). The rear end of the first planet gear (202) is connected to a rotating carrier sun gear (204), and three sets of second planet gears (205) are meshed on the outer side of the rotating carrier sun gear (204). The compensation ring assembly (5) includes a shape memory alloy compensation ring (501) installed at the front end of the sun gear (201) and the step position of the sun gear (204) of the rotating frame. A thin film heating element (502) is provided on one side of the shape memory alloy compensation ring (501), and a hydraulic compensation ring (503) is provided on the other side of the shape memory alloy compensation ring (501). The cooling component (3) includes a semiconductor cooling chip (305) embedded in the inner wall of the reducer (1).

2. The low-friction planetary reducer axial limiting structure according to claim 1, characterized in that: The axial limiting mechanism (2) further includes a first gear ring (203) meshing with the outside of the first planetary gear (202), a second gear ring (206) meshing with the outside of the second planetary gear (205), and an output wheel (207) connected to the rear end of the second planetary gear (205).

3. The low-friction planetary reducer axial limiting structure according to claim 2, characterized in that: A connecting shaft (209) is provided between one of the first planetary gears (202) and the carrier sun gear (204), and a connecting shaft (209) is also provided between one of the second planetary gears (205) and the output gear (207). The carrier sun gear (204) is provided with a non-tooth cylindrical step on the side facing the second planetary gear (205), and one of the compensation ring assemblies (5) is installed on the non-tooth cylindrical step.

4. The low-friction planetary reducer axial limiting structure according to claim 3, characterized in that: A heat-conducting ring (304) is provided between the semiconductor cooling chip (305) and the first gear ring (203) and the second gear ring (206). The cooling end of the semiconductor cooling chip (305) is in contact with the heat-conducting ring (304). A cooling fan (302) is provided on the lower side of the heating end of the semiconductor cooling chip (305). A bottom support (301) is provided on the outside of the cooling fan (302), and a dust cover (303) is installed at the end of the bottom support (301).

5. The low-friction planetary reducer axial limiting structure according to claim 1, characterized in that: The reducer (1) includes a housing (101), an end cover (102) is installed at the front end of the housing (101), and locking screws (106) are embedded around the connection between the end cover (102) and the housing (101). An input shaft (103) is provided at the middle of the front end of the end cover (102), and an output shaft (105) is provided at the middle of the rear end of the housing (101). An oil seal (104) is provided on the outside of the output shaft (105) and the input shaft (103).

6. The low-friction planetary reducer axial limiting structure according to claim 5, characterized in that: A temperature sensor (108) is embedded inside the end cap (102), and a controller (109) is provided below the temperature sensor (108). A bearing (208) is provided at the connection between the end cap (102) and the sun gear (201).

7. The low-friction planetary reducer axial limiting structure according to claim 6, characterized in that: The lubrication assembly (4) includes a lubricating oil tank (401) fixed above the housing (101), the front end of the lubricating oil tank (401) is connected to an accumulator (405) via a pipe, and the front end of the accumulator (405) is connected to a proportional valve (406) via a pipe.

8. The low-friction planetary reducer axial limiting structure according to claim 7, characterized in that: The output end of the proportional valve (406) is connected to two hydraulic supply pipes (403) and a lubricating oil output pipe (404), with the output end of the lubricating oil output pipe (404) facing the sun gear (204).

9. The low-friction planetary reducer axial limiting structure according to claim 8, characterized in that: The hydraulic compensation ring (503) has a T-shaped compensation component (504) that is slidably disposed inside it, and the hydraulic compensation ring (503) is connected to the hydraulic supply pipe (403).

10. The low-friction planetary reducer axial limiting structure according to claim 9, characterized in that: The bottom of the housing (101) is provided with a connecting groove (107), the bottom bracket (301) surrounds the outside of the connecting groove (107), and the accumulator (405) and the proportional valve (406) are provided with a protective frame (402) fixed above the housing (101).

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