A high-precision electric vehicle transfer case

Abstract

The application discloses a high-precision electric vehicle transfer case and relates to the technical field of electric vehicle transmission, which comprises a first hydraulic cylinder fixedly connected with the rotating shaft of a pedal and a second hydraulic cylinder arranged on a bottom plate; further comprising a meshing gear rotatably arranged on a transmission lever, wherein the meshing gear is always engaged with an output shaft gear. The high-precision electric vehicle transfer case presents high-torque rigid engagement in the form of'mating gear-gear slot' through a power transmission link, which does not affect the high dynamic response performance of the electric vehicle motor at all. When the driver makes a panic misfooting pedal operation, the system adaptively switches the transmission path from rigid engagement to low-torque capacity friction transmission in the form of 'friction pad-end face', which reserves sufficient correction time for the driver. The application avoids the risk of vehicle out-of-control caused by rough power cut-off in the prior art electronic scheme, and the safety uncertainty caused by signal processing delay and potential failure.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle transmission technology, and more specifically to a high-precision electric vehicle transfer case. Background Technology

[0002] Electric vehicles, due to the extremely fast torque response and high torque characteristics of their motors, while enhancing the driving experience, also harbor specific safety hazards. Especially in the high-regenerative "one-pedal mode," some drivers may panic in emergencies and mistakenly slam on the accelerator instead of the brake. In this situation, the enormous torque output from the motor at full power will be transmitted to the wheels without any buffering through the rigid transmission link of the transfer case, causing the vehicle to lurch forward violently, which can easily lead to an uncontrollable and serious traffic accident.

[0003] In existing technologies, solutions for such misoperations typically rely on electronic control systems. Specifically, the vehicle monitors the rate of change of pedal opening using pedal position sensors. Once the rate of change exceeds a preset threshold, it is determined to be a misoperation, and power output is immediately cut off or active braking is initiated. However, this "black and white" intervention method based on electrical signals has significant drawbacks: the instantaneous interruption of power can cause a significant longitudinal impact on the vehicle. This abrupt loss of control can exacerbate panic for a driver already under high stress, easily leading to more dangerous secondary operational errors. Furthermore, electronic systems have inherent time delays in signal sampling, processing, and execution, as well as reliability risks due to electromagnetic compatibility issues, software logic defects, or sensor failures, making it impossible to provide absolutely deterministic physical safety guarantees in extreme scenarios. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision electric vehicle transfer case that can perceive the driver's pedal operation rate as different physical parameters through a pure mechanical and hydraulic coupling logic. During normal operation, it maintains high-efficiency rigid transmission, while in case of panic-induced accidental pedal pressing, it adaptively switches the transmission path from rigid engagement to frictional sliding. Under the premise of maintaining vehicle controllability, it absorbs and dissipates excessive torque output in a flexible manner, ensuring driving safety and solving the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-precision electric vehicle transfer case, comprising a first hydraulic cylinder fixedly connected to the rotating shaft of the pedal, and a second hydraulic cylinder disposed on the base plate, wherein the rodless chamber of the first hydraulic cylinder is connected to the second hydraulic cylinder via an oil passage, and the piston rod of the second hydraulic cylinder is fixedly connected to a transmission lever, and the transmission lever is slidably disposed between the input shaft gear and the output shaft gear. It also includes a meshing gear rotatably mounted on the transmission lever, the meshing gear being constantly meshed with the output shaft gear; A mating gear is slidably disposed inside the meshing gear along the axial direction. A friction pad is connected to the end face of the mating gear facing the input shaft gear, and a first spring is connected between the mating gear and the friction pad. An expansion bladder is axially telescopically disposed on the input shaft gear, the expansion bladder having a shape that expands after being filled with a medium to push the mating gear out of the input shaft gear.

[0006] Preferably, the second hydraulic cylinder includes an internal annular cavity, a sliding cavity defined by the inner wall of the annular cavity, and an expansion cavity communicating with the sliding cavity and located on the side of the annular cavity. The main piston is slidably disposed in the sliding cavity, and the end of the main piston is fixedly connected to the transmission lever.

[0007] Preferably, a flow-limiting hole is formed on the inner side of the cavity wall of the sliding cavity, and the flow-limiting hole connects the sliding cavity with the annular cavity; The flow-limiting orifice has two relative positions on the sliding path of the main piston. In the first position, the flow-limiting orifice is located on the back side of the main piston, and hydraulic pressure preferentially pushes the main piston to move. In the second position, the flow-limiting orifice is located on the front side of the main piston, and hydraulic oil enters the annular cavity through the flow-limiting orifice.

[0008] Preferably, the device also includes a deformable piston disposed within the expansion cavity. The deformable piston includes an end face slidably disposed within the expansion cavity and a plurality of movable bladders slidably disposed radially on the side of the end face and extending and retracting axially. Multiple movable bladders are arranged in a circumferential array on the end face, and the movable bladders are interconnected by a corrugated pipe, which is also connected to the expansion bladder.

[0009] Preferably, the device also includes a trigger plate rotatably disposed within the expansion cavity, the trigger plate having an arc groove, and the arc groove cooperating with the movable bladder to guide the movable bladder to move centripetally or centrifugally. An overspeed disc is rotatably mounted on the base plate, and the overspeed disc is connected to the rotating shaft of the pedal via a transmission belt; The overspeed disk is equipped with three pendulums that rotate circumferentially, and the pendulums are held in place by a third spring.

[0010] Preferably, the trigger plate extends a second hydraulic cylinder from its end and is provided with a driven bevel gear, and the base plate is rotatably provided with a driving bevel gear. The end of the driving bevel gear is fixedly provided with limiting teeth, and after the pendulum swings, it abuts against the limiting teeth and drives them to rotate.

[0011] Preferably, a first pipe is provided on the annular cavity, and a second pipe is connected inside the expansion cavity, wherein the inner diameter of the first pipe is smaller than the inner diameter of the second pipe; The tail ends of the first pipeline and the second pipeline are connected together and connected to the rod chamber of the first hydraulic cylinder.

[0012] Preferably, a rotating interface is provided at the end of the input shaft, and the bellows of the expansion bladder and the movable bladder are interconnected through the rotating interface.

[0013] Preferably, the first hydraulic cylinder includes a hydraulic rod connected to the pedal shaft, and a second spring is sleeved on the hydraulic rod to keep it in an extended state.

[0014] Preferably, when the pedal is excessively depressed, the main piston slides along the sliding cavity and abuts against the end face of the deformable piston to compress the multiple movable bladders.

[0015] The high-precision electric vehicle transfer case provided by the present invention, as described above, has the following beneficial effects: 1. Under normal operating conditions, the power transmission link exhibits a high-torque rigid meshing of "cogwheel-tooth groove," which does not affect the high dynamic response performance of the electric vehicle motor. However, when the driver panics and accidentally presses the pedal, the system adaptively switches the transmission path from rigid meshing to low-torque capacity friction transmission of "friction pads and end faces." This switch does not cut off power, so the vehicle's jerking and loss of control sensation are lower. However, the rigid overload torque is greatly dissipated by the friction pads during the slippage process, only driving the vehicle to creep slowly, giving the driver sufficient time to correct the situation. This avoids the risk of vehicle loss of control caused by the abrupt power cut-off in existing electronic solutions, as well as the safety uncertainties caused by signal processing delays and potential failures.

[0016] 2. A flow-limiting orifice is formed on the inner side of the sliding chamber wall, and its position is switched with the sliding path of the main piston. In the first position, hydraulic pressure prioritizes the movement of the main piston, ensuring zero delay in gear engagement response. In the second position, the flow-limiting orifice switches to the positive side of the piston. On the one hand, it forces subsequent oil to bypass and circulate, decoupling the pedal travel after gear engagement from the transfer case position at the hydraulic level, so that the driver's continuous pedaling will not change the transmission state. On the other hand, the throttling effect of the flow-limiting orifice creates a continuous pressure difference before and after it. This pressure difference generates steady-state static pressure on the main piston, reliably hydraulically locking it in the position.

[0017] 3. Through a purely mechanical angular acceleration sensing mechanism consisting of an overspeed disc, a pendulum, and a third spring, as well as an arc groove guiding structure on the trigger plate, panic behavior is directly sensed from the source of the driving operation. When the driver suddenly slams on the pedal, the sudden angular acceleration of the overspeed disc causes the pendulum to overcome the tension of the third spring and be thrown out instantly under the action of centrifugal force, driving the trigger plate to rotate and causing the active bladder to converge towards the center, actively meeting the impact of the main piston.

[0018] 4. The annular cavity and the expansion cavity are connected to the rod cavity via a first pipe and a second pipe with different inner diameters, respectively, where the inner diameter of the first pipe is smaller than that of the second pipe. The difference in the physical parameters of the pipes themselves defines the fluid flow priority during system reset. When the driver quickly moves their foot away, the negative pressure in the rodless cavity overcomes the resistance of the flow-limiting orifice, slowly drawing the main piston back and executing the decoupling action of the transmission lever. Simultaneously, the positive pressure pulse in the rod cavity, due to the difference in flow resistance, mainly flows into the expansion cavity via the second pipe, maintaining the compression state of the deformable piston and the expansion bladder, ensuring that the mating gear is firmly held in place throughout the retraction process. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0020] Figure 1 This is an overall three-dimensional schematic diagram provided for an embodiment of the present invention; Figure 2 This is a schematic diagram of the input and output shafts of the transfer case provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the transmission lever structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the internal structure of the second hydraulic cylinder provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the expansion cavity and trigger plate structure provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the overspeed disc structure provided in an embodiment of the present invention; Figure 7 A schematic diagram of the structure of the first hydraulic cylinder provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of a deformable piston structure provided in an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures: 100. Transfer case; 200. Pedal; 10. Pedal shaft; 20. First hydraulic cylinder; 21. Rodless chamber; 21a. Hydraulic rod; 22. Rod chamber; 23. Second spring; 30. Oil circuit; 40. Base plate; 41. Rotating seat; 42. Drive bevel gear; 43. Restricting teeth; 50. Second hydraulic cylinder; 51. Annular chamber; 52. Sliding chamber; 53. Expansion chamber; 53a. Piston rod; 54. Main piston; 54b. Impact surface; 55. Flow limiting orifice; 60. Transmission lever; 70. Input shaft gear; 71. Tooth groove; 72. Input shaft; 80. Input... Output shaft gear; 90, meshing gear; 110, mating gear; 120, first spring; 130, friction pad; 140, expansion bladder; 150, deformable piston; 151, end face; 152, movable bladder; 153, bellows; 154, axial through hole; 160, first pipeline; 161, second pipeline; 170, rotary interface; 173, wear-resistant bushing; 180, trigger plate; 181, arc groove; 182, driven bevel gear; 190, overspeed disc; 191, transmission belt; 192, pendulum; 192a, hammerhead boss; 193, third spring. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] like Figure 1-8 As shown, a high-precision electric vehicle transfer case includes a first hydraulic cylinder 20 fixedly connected to the rotating shaft 10 of the pedal 200, and a second hydraulic cylinder 50 disposed on the base plate 40. The rodless chamber 21 of the first hydraulic cylinder 20 is connected to the second hydraulic cylinder 50 through the oil passage 30. The piston rod 53a of the second hydraulic cylinder 50 is fixedly connected to the transmission lever 60, and the transmission lever 60 is slidably disposed between the input shaft gear 70 and the output shaft gear 80. It also includes a meshing gear 90 rotatably mounted on the transmission lever 60, which is in constant mesh with the output shaft gear 80; A mating gear 110 is slidably disposed inside the meshing gear 90 along the axial direction. A friction pad 130 is connected to the end face of the mating gear 110 facing the input shaft gear 70, and a first spring 120 is connected between the mating gear 110 and the friction pad 130. An expansion bladder 140 is provided axially for telescopically extending on the input shaft gear 70. The expansion bladder 140 has a shape that expands after being filled with a medium to push the mating gear 110 out of the input shaft gear 70.

[0024] Specifically, the teeth of the input shaft gear 70 are spaced 71, the input shaft 72 is the driving component connecting to the motor, and the output shaft gear 80 is the driven component connecting to the load. When the driver presses the pedal 200 with a smooth force, the first hydraulic cylinder 20, which is linked to it, smoothly squeezes hydraulic oil through the oil passage 30 into the sliding chamber 52 of the second hydraulic cylinder 50, pushing the main piston 54 and the fixed transmission lever 60 to slowly move towards the input shaft gear 70. The meshing gear 90 mounted on the transmission lever 60 is constantly meshed with the input shaft gear 70. At this time, the mating gear 110 located inside it first contacts the end face of the input shaft gear 70 through the friction pad 130 at its end. This friction interface generates a flexible sliding torque, which gently pulls the output shaft gear 80 and the vehicle to synchronize with the speed of the input shaft 72 in a very short time. At the instant of speed synchronization, the mating gear 110, which was originally blocked from the tooth groove 71 due to the speed difference, will be smoothly pushed into the tooth groove 71 by the first spring 120. The power transmission path seamlessly switches from the low torque capacity sliding friction of the friction pad 130 and end face to the high torque capacity rigid locking of the mating gear 110 and tooth groove. At this time, the transfer case 100 is in a high-efficiency transmission state, and the high dynamic response performance of the motor is not affected in the slightest.

[0025] Furthermore, when the driver experiences a panic-induced misoperation, i.e., excessively depresses pedal 200, the adaptive system will activate an "abnormal" path. The expansion bladder 140 is forcibly inflated in a controlled manner. The axially expanding bladder directly applies its thrust to the front face of the mating gear 110, which is embedded in the tooth groove 71, overcoming the preload of the first spring 120 and physically pushing it out of the tooth groove 71. As the mating gear 110 is forcibly disengaged, the transmission link instantly reverts from rigid engagement to friction transmission mode. At this time, the system does not cut off power, so the vehicle experiences no jerking or loss of control; however, the original rigid overload torque is greatly dissipated by the friction pads 130 during the slippage process, effectively softening the torque ultimately transmitted to the wheels, only enough to drive the vehicle to creep slowly, thus preserving sufficient time for the driver to take over and correct the situation.

[0026] In the aforementioned technology, under normal operating conditions, the power transmission link exhibits a high-torque rigid meshing of "coupling gear 110-tooth groove 71," which does not affect the high dynamic response performance of the electric vehicle motor. However, when the driver panics and accidentally presses the pedal, the system adaptively switches the transmission path from rigid meshing to low-torque capacity friction transmission of "friction pad 130-end face." This switch does not cut off power, thus reducing the feeling of jerking and loss of control in the vehicle. However, the rigid overload torque is greatly dissipated by the friction pad during the slippage process, only driving the vehicle to creep slowly, thus preserving sufficient correction time for the driver. This avoids the risk of vehicle loss of control caused by abrupt power cut-off in existing electronic solutions, as well as the safety uncertainties caused by signal processing delays and potential failures.

[0027] As a further embodiment of the present invention, the second hydraulic cylinder 50 includes an internal annular cavity 51, a sliding cavity 52 defined by the inner wall of the annular cavity 51, and an expansion cavity 53 that communicates with the sliding cavity 52 and is located on the side of the annular cavity 51. A main piston 54 is slidably disposed in the sliding cavity 52, and the end of the main piston 54 is fixedly connected to the transmission lever 60.

[0028] Specifically, the cylindrical sliding cavity 52 constrains the axial movement of the main piston 54, thereby ensuring the displacement accuracy of the transmission lever 60, which is the geometric basis for achieving smooth and synchronous engagement. Coaxially surrounding the sliding cavity 52 is an annular cavity 51, which acts as a bypass and pressure-stabilizing buffer that does not participate in active propulsion, providing a secondary path for the oil via the flow-limiting orifice 55. On the radial side of the sliding cavity 52, a relatively spacious expansion cavity 53 is machined. This cavity does not move during normal operation; it is only activated when the main piston 54 overtravels. Since the flow-limiting orifice 55 in the sliding cavity 52 has switched to the positive side of the main piston 54, the oil from the extra deep press is bypassed, and the transmission lever 60 will not continue to move forward, avoiding accidental activation caused by slight foot vibrations. Simultaneously, if the pressing force continues to increase to the trigger threshold, the system will directly enter the friction drive mode, with the vehicle outputting only extremely low slip torque. This provides a low-speed driving mode similar to the creeping motion of an automatic transmission torque converter for urban traffic jams and parking in tight spaces.

[0029] As a further embodiment of the present invention, a flow-limiting hole 55 is provided on the inner side of the cavity wall of the sliding cavity 52, and the flow-limiting hole 55 connects the sliding cavity 52 with the annular cavity 51. The flow-limiting orifice 55 has two relative positions on the sliding path of the main piston 54. In the first position, the flow-limiting orifice 55 is located on the back side of the main piston 54, and hydraulic pressure preferentially pushes the main piston 54 to move. In the second position, the flow-limiting orifice 55 is located on the front side of the main piston 54, and hydraulic oil enters the annular cavity 51 through the flow-limiting orifice 55.

[0030] Specifically, the inner diameter of the flow-limiting orifice 55 is precisely calibrated, typically to the level of a few percent to several millimeters, to match the system's peak flow rate. In the initial stage of normal pedaling, oil enters the sliding chamber 52 from the oil passage 30 and flows directly to the back of the main piston 54. At this time, the flow-limiting orifice 55 is located on the side of the main piston 54 facing away from the incoming oil. Because the path resistance of the flow-limiting orifice 55 is much greater than the resistance of directly pushing the piston, the hydraulic pressure preferentially pushes the main piston 54 to move swiftly, achieving a zero-delay response from pedal action to gear engagement. When the main piston 54 reaches its predetermined position, its sealing ring surface just slides past the flow-limiting orifice 55, causing the flow-limiting orifice 55 to turn to the front of the main piston 54 bearing the main pressure. Thereafter, any additional oil from continuous pedaling will preferentially bypass and circulate through the flow-limiting orifice 55 to the low-pressure annular chamber 51 and the first pipeline 160. During this process, the throttling effect of the flow-limiting orifice 55 creates a continuous pressure difference on both sides, meaning the pressure on the sliding chamber 52 side is always higher than that on the annular chamber 51 side. This pressure difference generates a steady-state static pressure on the front of the main piston 54 toward the workstation. This force is sufficient to overcome any vibration or spring interference that might cause it to retract, and firmly hydraulically locks it in place at the workstation. The depth of the pedal 200 after gear engagement no longer affects the workstation status of the transfer case 100, while the sensitivity of the initial response remains unaffected, and reliable workstation holding capability is simultaneously achieved.

[0031] As a further embodiment of the present invention, it also includes a deformable piston 150 disposed in the expansion cavity 53. The deformable piston 150 includes an end face 151 slidably disposed in the expansion cavity 53, and a plurality of movable bladders 152 slidably disposed on the side of the end face 151 in the radial direction and extending and retracting in the axial direction. Multiple movable bladders 152 are arranged in a circular array on the end face 151. The movable bladders 152 are interconnected by a bellows 153, and the bellows 153 is connected to the expansion bladder 140.

[0032] Specifically, in the untriggered state, multiple bellows-type movable bladders 152 expand radially outward under the action of internal springs or the elasticity of their own materials, avoiding the normal stroke space of the main piston 54. At this time, the entire string of movable bladders, the bellows 153, and the expansion bladder 140 at the end constitute a completely sealed volume filled with hydraulic oil. When the main piston 54 violently impacts the end face 151 under excessive operating conditions, the displacement of the end face 151 forces all movable bladders 152 to undergo high-frequency axial compression. The instantaneous ultra-high pressure oil generated by the compression is transported to the expansion bladder 140 through the bellows 153 and the rotary interface 170, causing it to expand forcibly.

[0033] As a further embodiment of the present invention, it also includes a trigger plate 180 rotatably disposed in the expansion cavity 53, the trigger plate 180 having an arc groove 181, and the arc groove 181 cooperating with the movable bladder 152 to guide the movable bladder 152 to move centrifugally or centrifugally. An overspeed disc 190 is rotatably mounted on the base plate 40, and the overspeed disc 190 is connected to the rotating shaft 10 of the pedal 200 via a transmission belt 191. The overspeed disc 190 is circumferentially rotated and is equipped with three pendulums 192, which are held in place by a third spring 193.

[0034] Specifically, when the driver panics and instantly slams down pedal 200, the angular acceleration of shaft 10 exceeds a preset physical threshold, causing overdrive disc 190 to rotate synchronously at high speed. The pendulum 192, hinged to overdrive disc 190, senses this sudden angular acceleration, and its inertial centrifugal force instantly overcomes the tension of the third spring 193, violently throwing it outwards. This action directly drives trigger plate 180 to rotate, and its precisely calculated curvature arc-shaped groove 181 synchronously guides the previously open movable bladders 152 to converge towards the axis and tighten.

[0035] As a further embodiment of the present invention, the end of the trigger plate 180 extends into a second hydraulic cylinder 50 and is provided with a driven bevel gear 182. The base plate 40 is rotatably provided with an active bevel gear 42. The end of the active bevel gear 42 is fixedly provided with a limiting tooth 43. After the pendulum 192 swings, it abuts against the limiting tooth 43 and drives it to rotate.

[0036] Specifically, in steady state, the pendulum 192 is restrained by the third spring 193 and is in a retracted state, maintaining a disengagement gap with the rotating limiting teeth 43, without any contact. This fundamentally eliminates unnecessary wear and noise during normal driving. In congested urban traffic, the driver frequently presses and releases the pedal 200, causing the first hydraulic cylinder 20 and the second hydraulic cylinder 50 to work at high frequency, and the main piston 54 to reciprocate within the sliding chamber 52. However, the driver's pedaling speed is within the normal range each time, and the angular acceleration of the overspeed disc 190 is insufficient to cause the pendulum 192 to swing outward. The pendulum 192 and the limiting teeth 43 always maintain a non-contact gap, and the deformable piston 150 remains stationary within the expansion chamber 53. Only at the moment of overspeed, the pendulum 192 is thrown outward under the action of centrifugal force, and its precisely designed hammerhead protrusion 192a at its end engages or impacts the driving surface of the limiting teeth 43, instantly transferring the rotational kinetic energy of the overspeed disc 190 itself into the circumferential rotation of the driving bevel gear 42. By engaging with the driven bevel gear 182, a 90-degree change in power transmission direction is achieved, driving the trigger plate 180 to rotate within its plane. After this action is completed, once the acceleration disappears, the pendulum 192 immediately returns to its original position under the pull of the third spring 193 and disengages from the limiting teeth 43, automatically disconnecting the transmission chain.

[0037] As a further embodiment of the present invention, a first pipe 160 is provided on the annular cavity 51, and a second pipe 161 is connected in the expansion cavity 53. The inner diameter of the first pipe 160 is smaller than the inner diameter of the second pipe 161. The tail ends of the first pipeline 160 and the second pipeline 161 are connected and jointly connected to the rod chamber 22 of the first hydraulic cylinder 20.

[0038] Specifically, when the driver suddenly releases pedal 200, the hydraulic rod 21a of the first hydraulic cylinder 20 rapidly retracts under the action of the powerful second spring 23. At this time, a momentary negative pressure is generated in the rodless chamber 21. This negative pressure acts on the sliding chamber 52 through the oil passage 30, overcoming the throttling resistance of the flow limiting orifice 55, and slowly drawing back the main piston 54 along with the transmission lever 60. This is the only driving force for decoupling the transmission lever 60 from the power. At the same time, the volume of the rod chamber 22 shrinks sharply due to the retraction of the hydraulic rod 21a, generating a high-pressure pulse. Since the inner diameter of the first pipe 160 is much smaller than the inner diameter D2 of the second pipe, the difference in flow resistance is significant. Most of the oil will choose the path of least resistance, that is, directly rush into the expansion chamber 53 through the second pipe 161. The high-pressure oil independently impacts the back of the end face 151 of the deformable piston 150, generating a short-duration but powerful thrust. This ensures that the end face 151 remains compressed briefly after being released by the main piston 54, thus keeping the expansion bladder 140 continuously inflated. This keeps the gear 110 firmly in place, preventing accidental reset during the retraction of the transmission lever 60. This eliminates the risk of gear damage or unexpected locking due to pressure fluctuations during the reset process.

[0039] As a further embodiment of the present invention, a rotary interface 170 is provided at the end of the input shaft 71, and the bellows 153 of the expansion bladder 140 and the movable bladder 152 are interconnected through the rotary interface 170.

[0040] Specifically, the rotary interface 170 is precisely press-fitted into the end bore of the input shaft 72, and consists of a stainless steel outer shell and an internal high-pressure resistant lip seal and wear-resistant bushing [the above structures are common technical knowledge to those skilled in the art and will not be described in detail here]. Its rotor part rotates together with the input shaft 72, and has an axial hole and a radial hole machined inside to the bottom annular groove of the gear groove 71, ultimately delivering the high-pressure medium to the expansion bladder 140 without leakage. The stator part of the rotary interface 170 is connected to the interface fixed on the transfer case housing through an end face seal. This fixed interface is connected to the bellows 153 outlet of the deformable piston 150 through an internal hard pipe embedded in the cylinder wall of the second hydraulic cylinder 50 and a fluid channel in the expansion cavity 53. This combination of the fully enclosed internal pipeline and the end face seal rotary interface 170 allows high-pressure hydraulic oil to be transferred from a completely stationary hydraulic cylinder to the bottom of a high-speed rotating gear groove.

[0041] As a further embodiment of the present invention, the first hydraulic cylinder 20 includes a hydraulic rod 21a connected to the pedal shaft 10, and a second spring 23 is sleeved on the hydraulic rod 21a to keep it in an extended state.

[0042] Specifically, the second spring 23 makes the pedal feel of the electric vehicle closer to that of a traditional mechanical cable-operated throttle, and ensures that the pedal can reliably and autonomously return to its original position after release. Furthermore, the elastic force of the second spring 23 pushes the hydraulic rod 21a outward when static, providing a basic positive pressure to the rodless chamber 21, pre-tightening the entire hydraulic system, eliminating cavitation and free play, and ensuring that pressure is built up and transmitted to the second hydraulic cylinder 50 without delay the moment the pedal is pressed, guaranteeing sensitive and consistent response. When the driver's foot is quickly removed, this continuously stored elastic potential energy is converted into active kinetic energy that drives the pedal 200 and the hydraulic rod 21a to move rapidly in opposite directions.

[0043] As a further embodiment of the present invention, when the pedal 200 is over-pressed, the main piston 54 slides along the sliding cavity 52 and abuts against the end face 151 of the deformable piston 150 to compress the multiple movable bladders 152.

[0044] Specifically, only when the instantaneous flow rate entering the sliding cavity 52 far exceeds the discharge capacity of the flow-limiting orifice 55, and the oil in the cavity cannot be compressed or discharged in a very short time, forming a hydraulic cushion effect similar to a solid barrier, will the main piston 54 break through the hydraulic lock restricted by the position of the flow-limiting orifice 55 and overshoot. Its impact surface 54b violently impacts the end face 151 of the deformable piston 150.

[0045] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high-precision electric vehicle transfer case, comprising a first hydraulic cylinder (20) fixedly connected to a rotating shaft (10) of a pedal (200), and a second hydraulic cylinder (50) disposed on a base plate (40), wherein the rodless chamber (21) of the first hydraulic cylinder (20) is connected to the second hydraulic cylinder (50) via an oil passage (30), and the piston rod (53a) of the second hydraulic cylinder (50) is fixedly connected to a transmission lever (60), and the transmission lever (60) is slidably disposed between an input shaft gear (70) and an output shaft gear (80), characterized in that: It also includes a meshing gear (90) rotatably mounted on the transmission lever (60), the meshing gear (90) being constantly meshed with the output shaft gear (80); A mating gear (110) is slidably disposed inside the meshing gear (90) along the axial direction. A friction pad (130) is connected to the end face of the mating gear (110) facing the input shaft gear (70), and a first spring (120) is connected between the mating gear (110) and the friction pad (130). An expansion bladder (140) is provided axially for telescoping the input shaft gear (70). The expansion bladder (140) has a shape that expands after being filled with a medium to push the mating gear (110) out of the input shaft gear (70).

2. The high-precision electric vehicle transfer case according to claim 1, characterized in that, The second hydraulic cylinder (50) includes an internal annular cavity (51), a sliding cavity (52) defined by the inner wall of the annular cavity (51), and an expansion cavity (53) communicating with the sliding cavity (52) and located on the side of the annular cavity (51). The main piston (54) is slidably disposed in the sliding cavity (52), and the end of the main piston (54) is fixedly connected to the transmission lever (60).

3. A high-precision electric vehicle transfer case according to claim 2, characterized in that, A flow-limiting hole (55) is provided on the inner side of the cavity wall of the sliding cavity (52), and the flow-limiting hole (55) connects the sliding cavity (52) with the annular cavity (51). The flow-limiting orifice (55) has two relative positions on the sliding path of the main piston (54). In the first position, the flow-limiting orifice (55) is located on the back side of the main piston (54), and hydraulic pressure preferentially pushes the main piston (54) to move. In the second position, the flow-limiting orifice (55) is located on the front side of the main piston (54), and hydraulic oil enters the annular cavity (51) through the flow-limiting orifice (55).

4. A high-precision electric vehicle transfer case according to claim 3, characterized in that, It also includes a deformable piston (150) disposed in the expansion cavity (53), the deformable piston (150) including an end face (151) slidably disposed in the expansion cavity (53), and a plurality of movable bladders (152) slidably disposed on the side of the end face (151) and extending and retracting along the axial direction. Multiple movable bladders (152) are arranged in a circumferential array on the end face (151). The movable bladders (152) are interconnected by a bellows (153), and the bellows (153) is connected to the expansion bladder (140).

5. A high-precision electric vehicle transfer case according to claim 4, characterized in that, It also includes a trigger plate (180) rotatably disposed in the expansion cavity (53), the trigger plate (180) having an arc groove (181) provided thereon, and the arc groove (181) cooperating with the movable bladder (152) to guide the movable bladder (152) to move centripetally or centrifugally; An overspeed disc (190) is rotatably mounted on the base plate (40), and the overspeed disc (190) is connected to the rotating shaft (10) of the pedal (200) via a transmission belt (191). The overspeed disc (190) is circumferentially rotatable and has three pendulums (192), which are held in place by a third spring (193).

6. A high-precision electric vehicle transfer case according to claim 5, characterized in that, The trigger plate (180) extends to the end of a second hydraulic cylinder (50) and is provided with a driven bevel gear (182). The base plate (40) is rotatably provided with an active bevel gear (42). The end of the active bevel gear (42) is fixedly provided with a limiting tooth (43). After the pendulum (192) swings, it abuts against the limiting tooth (43) and drives it to rotate.

7. A high-precision electric vehicle transfer case according to claim 6, characterized in that, The annular cavity (51) is provided with a first pipe (160), and the expansion cavity (53) is connected to a second pipe (161). The inner diameter of the first pipe (160) is smaller than the inner diameter of the second pipe (161). The tail ends of the first pipeline (160) and the second pipeline (161) are connected and jointly connected to the rod chamber (22) of the first hydraulic cylinder (20).

8. A high-precision electric vehicle transfer case according to claim 7, characterized in that, A rotating interface (170) is provided at the end of the input shaft (71), and the bellows (153) of the expansion bladder (140) and the movable bladder (152) are connected to each other through the rotating interface (170).

9. A high-precision electric vehicle transfer case according to claim 8, characterized in that, The first hydraulic cylinder (20) includes a hydraulic rod (21a) connected to the pedal shaft (10), and a second spring (23) is sleeved on the hydraulic rod (21a) to keep it in an extended state.

10. A high-precision electric vehicle transfer case according to claim 1, characterized in that, When the pedal (200) is over-pressed, the main piston (54) slides along the sliding cavity (52) and abuts against the end face (151) of the deformable piston (150) to compress the multiple active bladders (152).

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