Electric drive axle of wheel loader

Abstract

An electric drive axle of a wheel loader comprises an axle housing and electric wheels arranged at the two ends of the axle housing, and the axle housing comprises a shell body and first flanges arranged at the two ends of the shell body; the electric wheel comprises a speed reducer arranged in the rim, a walking motor arranged in the axle housing and a brake arranged in the axle housing; the brake is arranged on a brake mounting seat at the inner end of the walking motor; the brake comprises a cylinder body, a piston arranged in the cylinder body, a fixed friction plate, a movable friction plate and a brake disc, the brake disc is arranged between the fixed friction plate and the movable friction plate, the piston can drive the movable friction plate to be close to the fixed friction plate, and the fixed friction plate is fixed on the cylinder body; one end of an output shaft of the walking motor extends and extends into the brake, the extending shaft of the walking motor is provided with a transition spline, and the brake disc is sleeved on the transition spline. The problem of low transmission efficiency of a traditional mechanical bridge is solved; the problem that an existing caliper type brake electric wheel structure mode needs a large space is solved. The problem that an existing wet brake electric wheel structure is high in manufacturing cost is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of loaders, in particular to an electric drive axle for a wheeled loader. Background Art

[0002] Under the background of the country's realization of the "dual carbon" goal, with the gradual maturity of the "three electrics" technology leading to the continuous reduction of the manufacturing cost of electrified products, electrification has become one of the important directions for the green development of loaders. Domestic loader manufacturers have begun to launch small-tonnage pure electric loaders one after another. Limited by the drive technology, the largest-tonnage electric loader currently only reaches 6-7 tons, and the drive axles of 12-ton loaders basically rely on imports, which restricts the electrification process of medium and large loaders. Therefore, it is necessary to study the electric drive axles for medium and large loaders.

[0003] The drive axles used in existing 12-ton wheeled loaders are all mechanical axles. After the power is transmitted to the drive axle, it drives the wheels through the main reducer, differential, half shaft, and wheel side reducer. The technical route adopted by 6-7 ton pure electric loaders is to use an electric drive box (motor + transmission) to transmit power to the traditional mechanical axle, without a dedicated electric drive axle. The technology route disclosed in Patent CN202010354622.X is this kind of technical route. In the process of loader electrification, this technical route can borrow the drive axle of the original fuel model, with a lower cost. However, due to the retention of the transmission system of the fuel model, the transmission efficiency is low, and it is impossible to get rid of the dependence on the traditional drive axle.

[0004] For electric drive loaders with a load capacity of more than 25 tons, electric wheel drive axles are usually adopted. The structural form of the electric wheel is similar to that of an electric drive mining dump truck. Usually, caliper brakes or wet brakes are adopted. Currently, the caliper brakes developed for electric wheels basically use imported parts, and the brakes are developed for large mining trucks, with a relatively large diameter of the brake disc. Therefore, the diameter of the wheel rim cannot be too small, and it is only applicable to models with a large enough tire size. The electric wheel of this type is disclosed in Patent CN111361358B. The wet brake electric wheel structure disclosed in Patent CN116729330A effectively solves the installation space problem, but the manufacturing cost of the electric wheel with wet brakes is very high. For electric loaders, electric braking will be the main braking, and mechanical braking mainly acts as auxiliary braking. If high-cost wet brakes are adopted, the cost performance is not appropriate. Therefore, the existing structural forms of electric wheels cannot be applied to 12-ton loaders. Summary of the Invention

[0005] The technical problem to be solved by the utility model is to provide an electric drive axle for a wheeled loader, which solves the problem of low transmission efficiency of the traditional mechanical axle; solves the problem of large required space of the existing electric wheel structure form with caliper brakes; and solves the problem of high manufacturing cost of the existing electric wheel structure with wet brakes.

[0006] To solve the above technical problems, the technical solution of the present utility model is as follows: A wheeled loader electric drive axle includes a bridge housing and electric wheels provided at both ends of the bridge housing. The bridge housing includes a housing body and first flanges provided at both ends of the housing body. The electric wheel includes a reducer provided inside the rim, a traveling motor provided inside the bridge housing, and a brake provided inside the bridge housing. The output shaft of the traveling motor is connected to the input shaft of the reducer. A second flange is provided at the outer end of the traveling motor, and the second flange is connected to the inner end of the reducer. A third flange is provided at the inner end of the reducer, and the third flange is connected to the first flange. The brake is provided on a brake mounting seat at the inner end of the traveling motor. The brake includes a cylinder block, a piston provided inside the cylinder block, a fixed friction plate, a movable friction plate, and a brake disc. A fourth flange is provided at the outer end of the cylinder block, and the fourth flange is connected to the brake mounting seat. A sealed oil chamber and an open brake chamber are provided inside the cylinder block. The piston is provided inside the oil chamber. The fixed friction plate, the movable friction plate, and the brake disc are provided inside the brake chamber. The brake disc is provided between the fixed friction plate and the movable friction plate. The piston can drive the movable friction plate to approach the fixed friction plate, and the fixed friction plate is fixed to the cylinder block. One end of the output shaft of the traveling motor extends and penetrates into the brake, and a transition spline is provided on the extended shaft of the traveling motor. The brake disc is sleeved on the transition spline. The principle of the present utility model: It realizes wheel-side drive in medium and large-sized loaders, eliminates the energy loss caused by transmission components such as the transmission, drive shaft, main reducer, and differential, and has higher transmission efficiency. At the same time, since there is no need for transmission shifting, the problem of transmission shifting jerks is solved; a combined service and parking brake is adopted to realize high-speed mechanical braking at the high-speed end in a small rim, with a compact structure and lower cost.

[0007] As an improvement, a fifth flange is provided at the outer end of the rim, and the fifth flange is connected to the outer end of the reducer.

[0008] As an improvement, an outer rib plate is provided between the housing body and the first flange.

[0009] As an improvement, the diameter of the brake is smaller than the diameter of the traveling motor.

[0010] As an improvement, the transition spline is columnar, the transition spline is sleeved on the output shaft of the traveling motor and has an interference fit. The inner side surface of the transition spline abuts against a snap ring sleeved on the output shaft, and the outer side surface of the transition spline abuts against an axial positioning plate. The axial positioning plate is fixed to the end of the output shaft by bolts.

[0011] As an improvement, a plurality of key grooves evenly distributed in the circumferential direction are provided on the outer wall of the transition spline.

[0012] The beneficial effects brought by the present utility model compared with the prior art are as follows:

[0013] 1. The wheel-side drive is realized in medium and large loaders for the first time, eliminating the energy loss caused by transmission components such as the transmission, drive shaft, main reducer, and differential. The transmission efficiency is higher. At the same time, since there is no need for transmission shifting, the problem of gear shifting jerks in the gearbox is solved;

[0014] 2. The integrated service and parking brake is adopted, and the high-speed mechanical brake is realized in the small wheel rim (rim inner diameter 774mm, axle housing inner diameter 578mm) for the first time, with a compact structure and lower cost;

[0015] 3. Fill the gap of domestic medium and large pure electric loader electric drive axles, provide an efficient and feasible power drive technology solution for the development of medium and large pure electric loaders, and promote the development and iteration of pure electric loaders;

[0016] 4. There is no longer a need for imported components such as engines, transmissions, and mechanical axles, completely solving the problem of "being held back" by key imported components;

[0017] 5. The brake disc is matched with the motor shaft by a transition spline. While improving the life of the transition spline, the processing difficulty of the motor shaft is effectively reduced. Brief Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the rear axle housing assembly.

[0019] Figure 2 It is a schematic diagram of the axle housing.

[0020] Figure 3 It is a schematic diagram of the electric wheel.

[0021] Figure 4 It is a cross-sectional view of the electric wheel.

[0022] Figure 5 It is a schematic diagram of the reducer and the rim matching. Detailed Implementation Modes

[0023] The present invention will be further described below in conjunction with the drawings of the specification.

[0024] The drive system of the wheel loader includes a front axle housing assembly and a rear axle housing assembly. The drive axle is located at the end of the transmission system. Its basic function is first to reduce speed and increase torque, that is, to reduce the speed transmitted by the travel motor, increase the torque transmitted by the travel motor, and reasonably distribute the torque according to the load required by the actual road, and drive the left and right wheels respectively. Secondly, the drive axle also has to bear the vertical force, longitudinal force, and lateral force transmitted from the road surface and the frame, as well as the driving torque, braking torque, and lateral force during turning.

[0025] Such as Figures 1 to 5As shown in the figure, the electric drive axle of the present utility model is described by taking the rear axle housing assembly as an example. It includes a bridge housing 1 and electric wheels 2 provided at both ends of the bridge housing 1. The bridge housing 1 includes a housing body 11, inner rib plates provided on the inner wall of the housing body 11, and first flanges 12 provided at both ends of the housing body 11; the housing body 11 is cylindrical, swing mechanism mounting seats 14 are provided on the front and rear sides of the housing body 11, an outer rib plate 13 is provided between the housing body 11 and the first flange 12, and a limit block 15 is also provided on the housing body 11. The electric wheel 2 includes a speed reducer 21 provided in the rim 3, a traveling motor 22 provided in the bridge housing 1, and a brake 23 provided in the bridge housing 1. The output shaft 222 of the traveling motor 22 is connected to the input shaft of the speed reducer 21. A second flange 221 is provided at the outer end of the traveling motor 22, and the second flange 221 is connected to the inner end of the speed reducer 21 to realize the mechanical fixed connection between the traveling motor 22 and the speed reducer 21; a third flange 211 is provided at the inner end of the speed reducer 21, and the third flange 211 is connected to the first flange 12 to realize the fixed connection between the speed reducer 21 and the bridge housing 1; the brake 23 is provided on a brake mounting seat 24 at the inner end of the traveling motor 22, and the diameter of the brake 23 is smaller than the diameter of the traveling motor 22. The brake 23 includes a cylinder block 231, a piston 232 provided in the cylinder block 231, a fixed friction plate 237, a movable friction plate 236, and a brake disc 238; a fourth flange 234 is provided at the outer end of the cylinder block 231, and the fourth flange 234 is connected to the brake mounting seat 24 to realize the fixed connection between the brake 23 and the traveling motor 22; a sealed oil chamber 235 and an open brake chamber 233 are provided in the cylinder block 231. The piston 232 is provided in the oil chamber 235, and the fixed friction plate 237, the movable friction plate 236, and the brake disc 238 are provided in the brake chamber 233. Since the brake chamber 233 is open, it is beneficial to the heat dissipation of the friction plate and the brake disc 238; the brake disc 238 is provided between the fixed friction plate 237 and the movable friction plate 236. One end of the piston 232 extends and is connected to the movable friction plate 236, and the fixed friction plate 237 is fixed on the cylinder block 231; one end of the output shaft of the traveling motor 22 extends and extends into the brake 23. A transition spline 224 is provided on the extended shaft 223 of the traveling motor. The brake disc 238 is sleeved on the transition spline 224. The transition spline 224 is columnar. The transition spline 224 is sleeved on the extended shaft 223 of the traveling motor and is in transitional fit. The inner side surface of the transition spline 224 abuts against a snap ring sleeved on the output shaft, and the outer side surface of the transition spline 224 abuts against an axial positioning plate 225. The axial positioning plate 225 is fixed to the end of the output shaft of the traveling motor by bolts. A plurality of key grooves are evenly distributed in the circumferential direction on the outer wall of the transition spline 224.

[0026] The utility model adopts an integral drive axle. Considering that the strength of the speed reducer 21 is too high, in order to reduce the weight of the motor, a scheme of connecting the speed reducer 21 with the axle housing assembly is used. Limited by the fact that the outer diameter of the axle housing cannot be too large, the speed reducer 21 can only be installed outside the axle housing. However, the width of the rim 3 is limited and cannot accommodate both the speed reducer 21 and the motor at the same time. Therefore, the travel motor 22 and the brake 23 are installed inside the axle housing.

[0027] Loaders generally work in a high-torque mode, and the required transmission ratio of the speed reducer 21 is about 80. The wheel-side speed reducer 21 generally adopts a planetary gear arrangement, and the power is split by multiple planetary gears and output coaxially, reducing the load on the shaft and bearings. Compared with other gear transmissions with parallel axes, it has the advantages of a compact structure, a large torque-to-mass ratio, etc. The wheel-side speed reducers 21 of electric wheels mainly adopt the NGW and NW types. Since the transmission ratio of the utility model is relatively large and the structure of the wheel-side speed reducer 21 on traditional mining dump trucks can meet the requirements, two additional stages of transmission need to be added at the front end. The utility model selects the NW type structure with a simpler structure. Since the torque increases gradually, the two additional stages of transmission can adopt a simpler parallel-axis type. The input end is connected to the travel motor 22 through a spline sleeve, and finally output through a ring gear. The speed reducer 21 is fixed to the rim by bolts.

[0028] As Figure 4 shown, for a pure-electric loader, mechanical braking only serves as auxiliary braking and parking braking, and a simpler dry-disc brake 23 can meet the requirements. In this project, due to very limited space and the fact that the vehicle is basically in a stationary state when the brake 23 is in use, a structure form with a single-side piston 232 is adopted, and the brake disc 238 is floating. Considering that the mining working conditions are very harsh and muddy water often enters the shaft, it is easy to cause the brake disc 238 to be stuck and affect the braking effect. Therefore, the cooperation accuracy between the brake disc 238 and the motor shaft is required to be relatively high. And since the spline of the brake disc 238 and the motor shaft need to run relative to each other frequently, there will be a certain amount of wear. Therefore, high requirements are imposed on the braking accuracy and surface hardness of the spline of the motor shaft. The motor shaft is a long shaft. If the above requirements are to be met, it will result in a very high processing cost. When replacing it after wear in the later stage, the motor needs to be disassembled, further increasing the cost. To solve this problem, the utility model designs a transition spline 224 for the brake disc 238. The transition spline 224 has an interference fit with the motor shaft. Since the diameter of the transition spline 224 can be made larger and has better wear resistance, it can be replaced-free throughout the entire service life. When driving, hydraulic oil is supplied to the brake 23. When the hydraulic pressure reaches 5 MPa, the piston 232 contracts inward against the spring pressure, and there is no pressure between the friction plate and the brake disc 238, and they can move relative to each other. When braking, by controlling the reduction of the hydraulic pressure supplied to the brake 23, the piston 232 extends outward under the action of the spring force, and then pushes the movable friction plate 236 to engage with the brake disc 238, thereby generating a braking torque.

Claims

1. A wheel loader electric drive axle, comprising an axle housing and electric wheels arranged at both ends of the axle housing, characterized in that: The bridge housing includes a housing and first flanges arranged at both ends of the housing; the electric wheel includes a reducer arranged in the rim, a travel motor arranged in the bridge housing and a brake arranged in the bridge housing; the output shaft of the travel motor is connected to the input shaft of the reducer, the outer end of the travel motor is provided with a second flange, the second flange is connected to the inner end of the reducer, the inner end of the reducer is provided with a third flange, the third flange is connected to the first flange, and the brake is arranged on the brake mounting seat at the inner end of the travel motor; the brake includes a cylinder body, a piston arranged in the cylinder body, a fixed friction plate, a movable friction plate, and a piston arranged in the cylinder body. The outer end of the cylinder body is provided with a fourth flange, and the fourth flange is connected to the brake mounting seat. A sealed oil chamber and an open brake chamber are provided in the cylinder body, and the piston is arranged in the oil chamber. The fixed friction plate, the movable friction plate and the brake disc are arranged in the brake chamber, and the brake disc is arranged between the fixed friction plate and the movable friction plate. The piston can drive the movable friction plate to approach the fixed friction plate, and the fixed friction plate is fixed on the cylinder body; one end of the output shaft of the travel motor is extended and extends into the brake, and the extended shaft of the travel motor is provided with a transition spline, and the brake disc is sleeved on the transition spline.

2. The electric drive axle of a wheel loader according to claim 1, characterized in that: The outer end of the rim is provided with a fifth flange, and the fifth flange is connected to the outer end of the reducer.

3. The electric drive axle of a wheel loader according to claim 1, characterized in that: An outer rib plate is arranged between the shell and the first flange.

4. The electric drive axle of a wheel loader according to claim 1, characterized in that: The diameter of the brake is smaller than the diameter of the travel motor.

5. The electric drive axle for a wheel loader according to claim 1, characterized in that: The transition spline is columnar, and the transition spline is sleeved on the output shaft of the travel motor and transitionally matched. The inner side of the transition spline abuts against the retaining ring sleeved on the output shaft, and the outer side of the transition spline abuts against the axial positioning plate. The axial positioning plate is fixed to the end of the output shaft by bolts.

6. The electric drive axle of a wheel loader according to claim 5, characterized in that: The outer wall of the transition spline is provided with a plurality of key grooves evenly distributed around the circumference.

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