Small light-weight electronic limited slip differential

Abstract

The invention relates to the technical field of vehicle power transmission, and discloses a small light electronic limited slip differential which comprises a supporting shell, a coupler shell, a differential half shaft, an ECU, an input hub, an output hub and a friction plate set. A piston is arranged on the inner side of the output hub and is in sliding fit with an inner spline on the inner circumference of the output hub through an outer spline to realize synchronous rotation of the two and axial movement of the piston; an oil supply channel and an axis channel which are communicated with each other are arranged in the supporting shell and the differential half shaft respectively and used for conveying high-pressure oil to a closed hydraulic cavity in the back of the piston. The pressure of the oil pump is adjusted through the ECU according to vehicle signals, the piston is driven to axially move to press the friction plate set, continuous stepless adjustment of the limited slip torque is achieved, the axial installation space is greatly compressed, the weight of the whole machine is reduced, mechanical friction loss and part failure risks are eliminated, and the service life of the whole machine is prolonged. The dynamic response characteristic, the control precision and the full life cycle reliability of the system are remarkably improved, and the intelligent upgrading requirements of mass production vehicle chassis are met.

Description

Technical Field

[0001] This invention relates to the field of vehicle powertrain technology, specifically to a small and lightweight electronic limited-slip differential. Background Technology

[0002] In the field of automotive transmission systems, the differential, as a key component for adjusting the speed difference of the drive wheels, is of great significance to the vehicle's steering performance and power distribution. As the automotive industry develops towards intelligence and high performance, electronic limited-slip differentials, which can achieve active distribution of drive torque, have become a core technology for improving vehicle driving stability and the ability to pass through complex road surfaces.

[0003] Traditional electronic limited-slip differentials use an ECU to collect vehicle driving signals and drive a hydraulic system to adjust the clamping force of the friction plate assembly, thereby limiting the differential's differential function. However, existing electronic limited-slip differentials still have significant shortcomings in terms of structural integration and lightweight design. Many traditional solutions require a thrust bearing between the piston and rotating components to transmit axial pressure. This not only results in excessively large axial mounting dimensions, increasing system weight and manufacturing difficulty, but also creates higher lubrication requirements and potential component failure risks due to the presence of a relative rotating friction pair. Furthermore, existing hydraulic control systems are often not simple enough in their oil circuit layout, making it easy for oil splashing or pressure loss to occur during high-speed rotation, making it difficult to guarantee high-precision continuous torque adjustment and rapid response to changing operating conditions.

[0004] Therefore, developing a lightweight electronic limited-slip differential with a more compact structure, more sensitive response, and high reliability is of great application value for optimizing vehicle power transmission efficiency and improving driving safety. Summary of the Invention

[0005] This invention addresses the technical shortcomings of existing limited-slip differentials, including low structural integration, excessive axial space occupation, high overall weight, and mechanical friction losses and potential failure risks due to the need for thrust bearings between the piston and rotating components. It proposes a compact and lightweight electronic limited-slip differential. Through an innovative hydraulic drive layout and integrated transmission structure design, this invention eliminates the rotating friction pair in traditional structures. While achieving high-precision control of power interruption and engagement, it significantly optimizes the system's dynamic response characteristics and space utilization.

[0006] This application provides a small and lightweight electronic limited-slip differential with the following technical solution: A small and lightweight electronic limited-slip differential, the basic frame of which includes a support housing, a coupler housing fastened to the support housing by disassembly bolts, a differential half-shaft arranged axially through, and an ECU responsible for system logic operation and execution command output; an input hub for inputting power and an output hub for outputting power are sleeved on the radial outer periphery of the differential half-shaft, and a friction plate assembly is arranged in the axial overlap area of ​​the input hub and the output hub; wherein, the far end of the input hub is synchronously rotated and connected to the vehicle's main differential housing, and the output hub is rigidly fixedly connected to the differential half-shaft by welding or spline structure; the friction plate assembly is composed of alternating stacked active friction plates and driven mating steel plates, the active friction plates are linked to the outer wall of the input hub through the inner spline of their radial inner edge, and the driven mating steel plates are linked to the inner peripheral wall of the output hub through the outer spline of their radial outer edge.

[0007] In the specific implementation of the hydraulic drive structure, a piston is provided on the inner side of the output hub, and an external spline is provided on the radially outer side of the piston. This external spline forms a sliding fit with the internal spline on the inner circumferential surface of the output hub, allowing the piston and output hub to lock in the circumferential direction to maintain completely synchronized rotation, while allowing the piston to displace in the axial direction. An oil supply channel is machined inside the support housing, and a shaft center channel is opened axially at the geometric center of the differential half-shaft. The outlet end of the oil supply channel is in fluid communication with the inlet end of the shaft center channel. High-pressure hydraulic oil generated by the oil pump enters the shaft center channel through the oil supply channel and is then... The final power is delivered to the closed hydraulic chamber formed between the piston back and the output hub. The ECU calculates the target lock-up torque by monitoring the vehicle's wheel speed difference, steering angle, and longitudinal / lateral acceleration signals in real time, and adjusts the current of the oil pump's drive motor accordingly. By changing the static pressure in the closed hydraulic chamber, the piston is driven to generate axial thrust. Under pressure, the piston overcomes the resistance of the reset element and moves towards the friction plate assembly. By changing the axial positive pressure on the friction plate assembly, the friction torque between the active friction plate and the driven mating steel plate is adjusted, thereby achieving stepless adjustment of power transmission between the input hub and the output hub.

[0008] Furthermore, to achieve precise axial positioning of the friction plate assembly and automatic piston reset, an annular groove is machined on the circumferential surface of the output hub, and a limit snap ring is embedded in the groove. The limit snap ring serves as a rigid support point for the friction plate assembly in the compression direction. By abutting against the outermost steel plate of the friction plate assembly, it converts the axial force applied by the piston into the compressive force between the friction plates. A pre-compressed disc spring is installed between the piston and the input hub. One end of the disc spring is supported by the limit step of the differential half-shaft, and the other end acts on the compression end face of the piston. When the ECU commands the oil pump to depressurize, the pressure in the closed hydraulic chamber drops rapidly. The disc spring uses its stored elastic potential energy to push the piston to move away from the friction plate assembly along the spline, so that the active friction plate and the driven mating steel plate of the friction plate assembly quickly disengage, eliminating residual drag torque.

[0009] Furthermore, in order to improve the overall rigidity of the transmission system and further reduce the radial envelope size, an integrated structure is formed by laser welding or electron beam welding between the output hub and the differential half shaft. This integrated connection method eliminates the fit clearance present in traditional spline connections, and transmits large torque through the continuous crystal structure formed by metal fusion welding. While reducing the thickness of the output hub, it also improves the dynamic balance performance of the differential half shaft under high-speed rotation.

[0010] Furthermore, regarding the sealing reliability of the shaft oil supply path, an oil seal is provided at the interface between the differential half-shaft and the input hub, and an oil seal is provided between the support housing and the input hub to form a static and dynamic dual sealing structure. The oil seal is installed in the sealing groove of the interface and forms a sealing pressure through radial interference compression to prevent high-pressure oil from leaking axially to the external environment. The oil seal, through a corresponding sealing structure, ensures the pressure stability of the oil circuit system, so that the hydraulic energy is completely converted into the axial mechanical energy of the piston.

[0011] Furthermore, a pressure relief valve is provided on the high side of the coupler housing or support housing, and a side oil chamber is connected through one side of the coupler housing or support housing. An oil filling plug is provided on one side of the side oil chamber. The inlet end of the pressure relief valve is connected to the side oil chamber of the oil pump for system overpressure protection and automatic venting. The pressure relief valve is equipped with a preload spring and a ball valve core. When the system pressure fluctuates due to extreme working conditions and exceeds the preset safety threshold, the ball valve core opens against the spring force, guiding the excess hydraulic oil back to the side oil chamber. This arrangement uses gravity to collect the air mixed in the oil circuit at the high position and discharge it through the pressure relief action, thereby improving the linearity of pressure control by eliminating cavitation in the hydraulic system.

[0012] Furthermore, to ensure that the radial runout of each rotating component is kept to an extremely low range under heavy load conditions, a needle roller bearing is press-fitted between the input hub and the differential half-shaft, and a double-row ball bearing is provided between the coupler housing and the differential half-shaft to achieve dual radial and axial positioning of the rotating components. The high radial load capacity of the needle roller bearing supports the cantilever end of the input hub. A double-row ball bearing is arranged between the support housing and the differential half-shaft to provide dual axial and radial positioning of the differential half-shaft. This bearing combination improves the mechanical efficiency of the system in the unlocked state by reducing the coefficient of rotational friction.

[0013] Furthermore, the hydraulic power source of the present invention adopts a highly integrated oil pump assembly. The oil pump is a disc-fixed axial piston pump, a cylinder-fixed axial piston pump, a radial piston pump, or an internal meshing vane pump. Its oil discharge port is directly connected to the oil supply channel inlet, and its oil suction port is connected to the side oil chamber. The oil pump is mounted on the side of the coupler housing through a flange. Its oil suction port is connected to the side oil chamber through a filter screen, and its oil discharge port is directly aligned with the oil supply channel inlet on the support housing. The hydraulic resistance loss is reduced by shortening the oil circuit length.

[0014] In summary, this application includes at least one of the following beneficial technical effects:

[0015] 1. First, this invention directly mounts the piston onto the output hub via an external spline, ensuring complete synchronization between the piston, the rotating output hub, and the differential half-shaft. This structural design completely eliminates the thrust bearing that must be located between the stationary piston and the rotating friction plate assembly in traditional electronic limited-slip differentials. By eliminating this large rolling or sliding friction pair, this invention achieves significant axial dimension reduction, allowing the entire limited-slip mechanism to be integrated into a very small housing space, significantly reducing the overall weight. At the same time, eliminating the thrust bearing effectively avoids the risk of system failure due to bearing fatigue pitting or cage breakage, and improves the reliability of the product throughout its entire life cycle by reducing the number of vulnerable parts.

[0016] 2. Secondly, this invention achieves efficient transmission of hydraulic power through a axial oil supply path. High-pressure oil enters from the center of the differential half-shaft. This path arrangement places the oil supply point at the center of the rotation axis, greatly reducing the centrifugal resistance when the oil enters the rotating cavity. After entering the closed hydraulic cavity on the back of the piston, the centrifugal force field generated by the synchronous rotation of the piston helps to evenly distribute the oil pressure in the circumferential direction of the piston. By eliminating local pressure fluctuations, the control accuracy of torque distribution is improved. This deep integration of electromechanical and hydraulic systems enables the system to achieve continuous stepless adjustment from zero torque to full lock-up torque. By precisely controlling the slipping state of the friction plate group, it meets the power distribution needs of the vehicle under various complex working conditions such as starting on icy and snowy roads, high-speed cornering stability control, and off-road extrication.

[0017] 3. Furthermore, this invention possesses extremely high response speed and smooth operation. Due to the spline connection between the piston and the output hub, its axial movement guidance is excellent. Combined with the low-stiffness, long-stroke disc spring design, the piston can instantly generate displacement after receiving hydraulic commands. During the limited-slip function release phase, the strong reset action of the disc spring, combined with the centrifugal oil discharge effect of the friction plate assembly, quickly opens the friction plate gap, preventing the friction plates from dragging and heating up in the non-working state, thus improving the vehicle's fuel economy. In addition, the high-position pressure relief valve design not only provides pressure overload protection but also maintains the incompressibility of the hydraulic medium through continuous venting, shortening the system pressure build-up time constant by increasing hydraulic stiffness.

[0018] 4. Finally, while achieving active limited-slip function, this invention perfectly retains and takes into account the basic functions of traditional open differentials. Under normal driving conditions where the ECU does not issue a limited-slip command, the friction plate assembly is in a completely free state, and there is no rigid constraint between the input and output hubs. By allowing a speed difference between the differential half-shaft and the vehicle's main differential housing, the kinematic coordination of the inner and outer wheels during cornering is ensured. This "on-demand intervention" working mode, through flexible torque management, provides the vehicle with stronger power limits and safety guarantees without changing the driver's traditional driving habits, through the optimization of the underlying hardware structure.

[0019] In summary, this invention, through its simplified structure, integrated functions, and scientifically planned hydraulic paths, addresses the pain points of existing limited-slip differentials, such as their heaviness, complexity, and vulnerability to damage, and provides a lightweight power distribution solution that can be widely applied in mass-produced vehicles. By deeply applying piston synchronous rotation technology, this invention reduces manufacturing and maintenance costs while laying a solid hardware foundation for the intelligent upgrading of vehicle chassis systems. The technical solution is described in detail, with clear connections between components, a rigorous power transmission path, and strict control logic, demonstrating strong engineering feasibility. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0021] Figure 2 This is a rear-view stereoscopic structural diagram of the present invention;

[0022] Figure 3 This is a frontal cross-sectional view of the present invention.

[0023] Figure 4 for Figure 3 Enlarged view of point A in the middle;

[0024] Figure 5 This is a schematic diagram of the supporting shell structure of the present invention;

[0025] Figure 6 This is a schematic diagram of the structure of the coupler housing of the present invention;

[0026] Figure 7 This is a schematic diagram of the differential half-shaft and output hub of the present invention;

[0027] Figure 8 This is a schematic cross-sectional view of the differential half-shaft of the present invention.

[0028] Explanation of reference numerals in the attached drawings: 1. Support housing; 2. Coupler housing; 21. Removal bolt; 3. Differential half-shaft; 4. Input hub; 5. Output hub; 6. Limiting circlip; 7. Friction plate assembly; 8. Piston; 9. Disc spring; 10. Needle roller bearing; 11. Ball bearing; 12. Oil pump; 121. Side oil chamber; 122. Pressure relief valve; 123. Oil filler plug; 13. ECU; 14. Oil supply channel; 15. Shaft channel; 16. Oil seal one; 17. Oil seal two. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The small and lightweight electronic limited-slip differential involved in the present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figures 1 to 8 This embodiment provides a small, lightweight electronic limited-slip differential, mainly used in automotive transmission systems. It achieves active torque distribution between the left and right half-shafts through mechatronic integrated control. The external frame of the device consists of a support housing 1 and a coupler housing 2, which are fastened together by circumferentially distributed disassembly bolts 21, forming an internally sealed working space. A differential half-shaft 3 is axially inserted at the center of the support housing 1 and at the corresponding position of the coupler housing 2. The differential half-shaft 3 is the core component for power output, with an input hub 4 for inputting power and an output hub 5 for outputting power fitted on its outer periphery. The distal end of the input hub 4 is synchronously rotated and connected to the vehicle's main differential housing via a spline structure, thereby receiving drive torque from the engine or motor. The output hub 5 is rigidly fixed to the differential half-shaft 3 via laser welding, forming a... Figure 7 and Figure 8 The integrated component shown; this welded structure eliminates the mating clearance of traditional spline connections, significantly improves the stiffness of torque transmission while reducing the radial thickness of the output hub 5, and optimizes the dynamic balance performance under high-speed rotation.

[0031] Within the axially overlapping area of ​​the input hub 4 and the output hub 5, a core actuator friction plate group 7 is provided. The friction plate group 7 is composed of multiple active friction plates and driven mating steel plates stacked alternately. The active friction plates are linked to the outer splines on the outer wall of the input hub 4 via the inner splines on their radial inner edges, causing them to rotate synchronously with the vehicle's main differential housing. The driven mating steel plates are linked to the inner splines on the inner circumferential wall of the output hub 5 via the outer splines on their radial outer edges, causing them to rotate synchronously with the differential half-shaft 3. On the circumferential surface of the output hub 5, a limiting snap ring 6 is embedded in the annular groove at the end of the output hub 5. The limiting snap ring 6 abuts against the outermost steel plate of the friction plate group 7, providing axial rigid support for the friction plate group 7 and preventing the friction plates from axially moving under pressure.

[0032] The hydraulic actuator of this invention adopts an innovative synchronous rotation design; please refer to... Figure 3 and Figure 4 The piston 8 is located inside the output hub 5, and an external spline is machined on the radially outer side of the piston 8. This external spline forms a sliding fit with the internal spline on the inner circumferential surface of the output hub 5. This connection method allows the piston 8 to be completely locked in the circumferential direction with the output hub 5 and the differential half-shaft 3, that is, the three maintain completely synchronous rotation at any speed. At the same time, the piston 8 has the freedom to generate displacement in the axial direction. Since there is no relative speed difference between the piston 8 and the rotating friction plate assembly 7, the present invention completely eliminates the thrust bearing that must be set between the stationary piston and the rotating assembly in the traditional electronic limited-slip differential. This improvement eliminates the large rolling friction pair, compresses the axial installation size of the limited-slip differential to less than 60% of the traditional structure, and avoids the risk of bearing fatigue failure.

[0033] A pre-compressed disc spring 9 is provided between the piston 8 and the input hub 4; one end of the disc spring 9 is supported by the limiting step of the differential half shaft 3, and the other end acts on the pressure end face of the piston 8; the disc spring 9 always provides the piston 8 with an initial elastic force away from the friction plate group 7, ensuring that the piston 8 and the friction plate group 7 maintain a preset disengagement gap in the non-working state; in order to ensure the sealing of the hydraulic system, an oil seal 16 is provided at the mating interface between the differential half shaft 3 and the input hub 4, and an oil seal 17 is provided between the support housing 1 and the input hub 4, forming a static and dynamic double sealing structure to ensure the pressure stability of the closed hydraulic chamber, so that the hydraulic energy entering the chamber is completely converted into mechanical energy to drive the piston 8 to move.

[0034] The hydraulic power source is provided by an oil pump 12 installed on the side of the coupler housing 2; the oil pump 12 is a disc-fixed axial piston pump, a cylinder-fixed axial piston pump, a radial piston pump, or an internal meshing vane pump, with its discharge port directly connected to the inlet of the oil supply channel 14, and its suction port connected to the side oil chamber 121; the suction port of the oil pump 12 is connected to the side oil chamber 121 through a filter screen, and the discharge port is directly connected to the oil supply channel 14 on the support housing 1; please refer to Figure 3 and Figure 5 The oil supply channel 14 is machined inside the solid of the support housing 1, and its outlet end points to the differential half shaft 3. At the geometric center of the differential half shaft 3, a shaft center channel 15 is opened along the axial direction. The oil supply channel 14 and the shaft center channel 15 are kept in fluid communication at the intersection, and high pressure oil enters the interior of the rotating differential half shaft 3 through this connection.

[0035] The intelligent control of this invention is achieved by ECU13; ECU13, based on wheel speed difference, steering angle, and acceleration signals, adjusts the current of the drive motor of oil pump 12 to achieve stepless adjustment of the pressure in the closed hydraulic chamber, thereby controlling the clamping force of friction plate assembly 7 and achieving continuous adjustment of the limited slip torque; ECU13 monitors vehicle operating data in real time via the vehicle CAN bus or dedicated sensor harness; a pressure relief valve 122 is provided on the high side of the coupler housing 2 or support housing 1, and a side oil chamber 121 is connected through one side of the coupler housing 2 or support housing 1. An oil filling plug 123 is provided on one side of 21. The inlet end of the pressure relief valve 122 is connected to the side oil chamber 121 of the oil pump 12 for system overpressure protection and automatic venting. The pressure relief valve 122 is equipped with a pre-tightening spring and a ball valve core. When the system pressure exceeds the safety threshold, it automatically opens to guide the hydraulic oil back to the side oil chamber 121. Since the pressure relief valve 122 is located at a high position in the direction of gravity, the air mixed in the oil circuit will naturally accumulate here. Automatic venting is achieved by the intermittent opening of the pressure relief valve 122, thereby eliminating cavitation in the hydraulic system and improving the linearity of pressure control.

[0036] In terms of the support structure, in order to ensure that the radial runout of each rotating component is in an extremely low range under heavy load conditions, a needle roller bearing 10 is press-fitted between the input hub 4 and the differential half shaft 3, using its high radial load capacity to support the input hub 4; a double row ball bearing 11 is provided between the coupler housing 2 and the differential half shaft 3, and the differential half shaft 3 is precisely positioned axially and radially by the ball bearing 11 to reduce overall mechanical loss.

[0037] The specific operating principle and process of the miniaturized and lightweight electronic limited-slip differential of this invention are as follows:

[0038] S1: During the driving process after the vehicle starts, the ECU13 collects the speed sensor signals of each wheel, the steering wheel angle signal, the longitudinal acceleration and the lateral acceleration data in real time at a frequency of milliseconds. These data are sent to the built-in differential control model. By comparing the real-time speed difference between the left and right drive wheels with the theoretical speed difference, the slip ratio of the current vehicle is calculated (ECU13 is a conventional technology in this field, and will not be described in detail in this application).

[0039] S2: When the vehicle enters a wet or muddy road or is cornering at its limit, if the ECU13 detects that the slip rate of a single drive wheel exceeds a preset logic threshold (e.g., more than 15%), it determines that the wheel on that side is at risk of slipping. The ECU13 immediately calculates the required compensation torque based on the degree of slip and converts it into a target hydraulic value, and outputs the corresponding pulse width modulation signal to the drive motor of the oil pump 12.

[0040] S3: After receiving the drive command, the oil pump 12 starts up quickly and builds up pressure, drawing hydraulic oil from the side oil chamber 121; the high-pressure oil flows through the oil supply channel 14 in the support housing 1, passes through the sealing interface formed by the O-ring 16, and enters the shaft channel 15 at the center of the differential half shaft 3; subsequently, the high-pressure oil flows axially and finally fills the closed hydraulic chamber between the back of the piston 8 and the output hub 5.

[0041] S4: As the static pressure inside the closed hydraulic chamber increases, the hydraulic thrust on the piston 8 gradually increases; when the thrust exceeds the preload of the disc spring 9, the piston 8 begins to slide axially along the inner spline of the output hub 5 toward the friction plate group 7; during this process, as the piston 8 and the hydraulic oil rotate at high speed with the output hub 5, the centrifugal force generated by the hydraulic oil forms an additional pressure on the radial outer side of the hydraulic chamber; this centrifugal pressure compensation effect enables the piston 8 to obtain a more stable clamping force under high-speed rotation, offsetting the pressure fluctuations that may occur at high speed.

[0042] S5: The end face of piston 8 is tightly fitted with friction plate assembly 7, applying continuous and controllable axial positive pressure to the active friction plate and driven mating steel plate. The lubricating oil film between the friction plates thins under pressure, generating strong shear friction and mechanical contact friction, thereby establishing a flexible to rigid power connection between input hub 4 and output hub 5; the drive torque originally transmitted to the slipping wheel is forcibly transferred to the differential half-shaft 3 on the other side with good grip through the friction torque generated by friction plate assembly 7; by adjusting the output pressure of oil pump 12, ECU 13 can achieve continuous stepless adjustment from 0 Nm to the maximum lock-up torque, thereby helping the vehicle to get out of trouble smoothly or improve the stability of cornering.

[0043] S6: When ECU13 detects that the speed difference between the left and right wheels of the vehicle has returned to the normal range and determines that the slippage condition has been resolved, it immediately instructs oil pump 12 to stop working or switch to low-pressure relief mode; the pressure in the closed hydraulic chamber is quickly released, and the hydraulic oil returns to the side oil chamber 121 through the shaft channel 15 and the oil supply channel 14; at this time, the compressed disc spring 9 releases the stored elastic potential energy and pushes the piston 8 to quickly return to its original axial position along the spline; the friction plate group 7 quickly opens the gap under the centrifugal throwing action of the lubricating oil, and the friction torque between the input hub 4 and the output hub 5 is completely eliminated. The system returns to the free differential state of the open differential, avoiding dragging, friction heating and fuel consumption in the non-working state.

[0044] In practical applications, such as when a vehicle starts on an icy or snowy road, if the left drive wheel is on the ice, its friction is extremely low. A traditional open differential would cause the left wheel to spin freely while the right wheel has no power. At this time, the ECU13 of this invention establishes hydraulic pressure and presses the friction plate group 7 in a very short time (usually less than 100ms) through steps S1 to S5, locking the engine torque and transmitting it to the right half-shaft with traction, allowing the vehicle to start smoothly. When driving straight on a highway, the system is in the reset state described in S6, the piston 8 is completely separated from the friction plate, and the differential exhibits a standard open structure, ensuring optimal transmission efficiency.

[0045] This invention achieves synchronous rotation by connecting the piston 8 and the output hub 5 via a spline connection. This not only eliminates the complex thrust bearing and simplifies the mechanical structure, but also reduces the centrifugal resistance of the oil entering the rotating chamber through the shaft oil supply path 15. This deeply integrated electromechanical-hydraulic structure enables the limited-slip differential to meet stringent torque distribution requirements while achieving true miniaturization and weight reduction. Through the in-depth application of piston synchronous rotation technology, this invention reduces manufacturing and maintenance costs while laying a solid hardware foundation for the intelligent upgrading of vehicle chassis systems.

[0046] Furthermore, the friction plate group 7 in this embodiment uses a wet paper-based friction material, which has a stable coefficient of friction and excellent heat dissipation performance when wetted by hydraulic oil. Under the condition of frequent piston 8 movement, the paper-based friction plate can store and discharge oil through surface micropores, ensuring smooth torque transmission and avoiding vibration or abnormal noise. The rigid limiting function of the limit spring 6 and the elastic restoring function of the disc spring 9 complement each other. By precisely controlling the stroke of the piston 8, the intervention and withdrawal of the limited slip function have extremely high repeatability.

[0047] In summary, this invention, through its simplified structure, integrated functions, and scientifically planned hydraulic path, addresses the pain points of existing limited-slip differentials, such as their heaviness, complexity, and vulnerability to damage, and provides a lightweight power distribution solution that can be widely applied in mass-produced vehicles. Its power transmission path is clear: vehicle power → vehicle main differential housing → input hub 4 → friction plate assembly 7 (pressed by piston 8) → output hub 5 → differential half-shaft 3. Its hydraulic control path is equally rigorous: side oil chamber 121 → oil pump 12 → oil supply channel 14 → shaft channel 15 → closed hydraulic chamber → pushing piston 8. This closed-loop control system, combined with optimized mechanical structure, significantly improves the vehicle's passability and safety under various complex operating conditions.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A small and lightweight electronic limited-slip differential, comprising a support housing (1), a coupler housing (2) fastened to the support housing (1) by a disassembly bolt (21), a differential half-shaft (3) axially extending through the support housing (1), and an ECU (13), characterized in that, Also includes: Oil pump (12) electrically connected to the ECU (13); The input hub (4) and output hub (5) are fitted on the radial outer periphery of the differential half shaft (3); Friction plate group (7) is set in the axially overlapping area of ​​input hub (4) and output hub (5). The output hub (5) is provided with a piston (8) on its inner side. The piston (8) slides with the inner spline on the inner circumference of the output hub (5) through the external spline, so as to realize the synchronous rotation and axial movement of the piston (8) and the output hub (5). The support housing (1) is provided with an oil supply channel (14), and the differential half shaft (3) is provided with a shaft center channel (15). The oil supply channel (14) and the shaft center channel (15) are connected to each other and are used to deliver high pressure oil to the closed hydraulic cavity formed between the back of the piston (8) and the output hub (5). The ECU (13) adjusts the pressure of the oil pump (12) according to the vehicle signal, drives the piston (8) to move axially to press the friction plate group (7), and realizes continuous adjustment of the limited slip torque.

2. The compact and lightweight electronic limited-slip differential according to claim 1, characterized in that, The output hub (5) has an annular groove on its surface, and a limiting spring (6) is embedded in the groove. The limiting spring (6) abuts against the outermost steel plate of the friction plate group (7) to provide axial rigid support.

3. A small and lightweight electronic limited-slip differential according to claim 1, characterized in that, A pre-compressed disc spring (9) is provided between the piston (8) and the input hub (4). One end of the disc spring (9) is supported by the limiting step of the differential half shaft (3), and the other end acts on the piston (8) for automatic reset of the piston (8).

4. A compact and lightweight electronic limited-slip differential according to claim 1, characterized in that, A needle roller bearing (10) is press-fitted between the input hub (4) and the differential half shaft (3), and a double-row ball bearing (11) is provided between the coupler housing (2) and the differential half shaft (3) to achieve radial and axial dual positioning of the rotating components.

5. A compact and lightweight electronic limited-slip differential according to claim 1, characterized in that, Oil seal 1 (16) is provided at the interface between the differential half shaft (3) and the input hub (4), and oil seal 2 (17) is provided between the support housing (1) and the input hub (4) to form a static and dynamic double sealing structure.

6. A compact and lightweight electronic limited-slip differential according to claim 1, characterized in that, It also includes a pressure relief valve (122) located on the high side of the coupler housing (2) or the support housing (1). The coupler housing (2) or the support housing (1) has a side oil chamber (121) that is connected to the oil suction port of the oil pump (12) through one side. An oil filling plug (123) is provided on one side of the side oil chamber (121).

7. A compact and lightweight electronic limited-slip differential according to claim 1, characterized in that, The oil pump (12) is a disc-fixed axial piston pump, a cylinder-fixed axial piston pump, a radial piston pump or an internal meshing vane pump. Its oil outlet is directly connected to the inlet of the oil supply channel (14), and its oil suction port is connected to the side oil chamber (121).

8. A compact and lightweight electronic limited-slip differential according to claim 1, characterized in that, The output hub (5) and the differential half shaft (3) are integrated into a single structure by laser welding or electron beam welding, which is used to eliminate the fit clearance and improve the torque transmission stiffness and dynamic balance performance.

9. A small and lightweight electronic limited-slip differential according to claim 1, characterized in that, The friction plate group (7) is composed of alternating stacked active friction plates and driven dual steel plates. The active friction plates are linked to the input hub (4) through internal splines, and the driven dual steel plates are linked to the output hub (5) through external splines.

10. A compact and lightweight electronic limited-slip differential according to claim 1, characterized in that, The ECU (13) adjusts the current of the drive motor of the oil pump (12) according to the wheel speed difference, steering angle and acceleration signal to realize stepless adjustment of the pressure in the closed hydraulic chamber, thereby controlling the clamping force of the friction plate group (7).

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