An electrically controlled gear shifting actuator of a special engineering vehicle and a method for controlling the same

Abstract

The present application relates to vehicle electric control gear shifting technical field, specifically disclose a kind of electric control gear shifting actuator of special engineering vehicle, including shell and the drive mechanism and control mechanism being arranged in shell, drive mechanism includes electric push rod, control mechanism includes the control board card located above electric push rod;Shell is equipped with spring return mechanism connected with electric push rod, spring return mechanism is connected with shift fork rod on the side away from shell;Spring return mechanism includes sliding seat and the telescopic component in sliding seat, two ends of telescopic component are connected with electric push rod and shift fork rod respectively;Sliding seat is also equipped with the pressure sensor located in the side of shift fork rod close to telescopic component one side portion;Electric push rod and pressure sensor are electrically connected with control board card.The present application further discloses a kind of electric control gear shifting actuator of special engineering vehicle's execution control method.This scheme can adjust the travel speed of electric push rod, realizes the regulation and control to external load pushing force, can greatly improve work reliability.

Description

Technical Field

[0001] This invention relates to the field of vehicle electronic shifting technology, specifically providing an electronic shifting actuator and its execution control method for a special engineering vehicle. Background Technology

[0002] Special vehicles are vehicles designed and equipped for specific tasks. They are typically used in rescue and emergency response, engineering operations, transporting special goods, environmental protection, public services, agricultural operations, scientific research and exploration, entertainment and sports, communication and command, and military applications. Examples include ambulances, fire trucks, rescue vehicles, armored vehicles, tanks, missile launchers, excavators, cranes, bulldozers, tank trucks, chemical transport vehicles, refrigerated trucks, garbage trucks, road sweepers, water trucks, police cars, postal vehicles, school buses, tractors, harvesters, geological exploration vehicles, scientific research vehicles, racing cars, motorcycles, mobile communication vehicles, and command vehicles. In these applications, special vehicles play a vital role in social production and daily life, serving as key factors in improving engineering efficiency and ensuring engineering safety and quality.

[0003] Bulldozers, as a type of special vehicle, are used to level land and slab the ground. They are commonly used in land reclamation and road construction. In the design of special vehicle bulldozers, according to the usage requirements of bulldozing and driving conditions, two-speed side reducers are usually installed on the left and right sides of the vehicle body. Different controllable transmission ratios are used for power transmission. The bulldozing condition is the higher load gear, and the driving condition is the relatively light load gear. Different spur gears are used for the two conditions, while the planetary gear set is shared. When shifting gears, the lever drives the gear plate, so that the input shaft connects to the bulldozing spur gear or the driving spur gear, thereby achieving the transmission ratio requirements for the two conditions.

[0004] Bulldozers include an electronically controlled shift actuator used to operate the two-speed shift fork of the side reducer, enabling the side reducer to switch between bulldozing and driving modes. Existing electronically controlled shift actuators mainly face the following problems: 1. The engagement of the drive gear and the spur gear pair requires control of the thrust to avoid excessive gear meshing impact causing shifting shock and gear damage; 2. There is a possibility of tooth collision during spur gear meshing. The actuator needs to maintain a certain thrust during gear engagement, or when tooth collision occurs and the push rod extension is obstructed, until the spur gear pair is aligned and engaged.

[0005] In existing technologies, conventional electric actuators can only stop or retract when encountering resistance, and cannot apply extension force. To solve this problem, designing an electronically controlled gear shifting actuator for special engineering vehicles and its execution control method is an urgent issue to be addressed. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides an electronically controlled gear shifting actuator for special engineering vehicles and its execution control method.

[0007] This invention provides an electronically controlled gear shifting actuator for a special engineering vehicle, specifically comprising a housing and a drive mechanism and a control mechanism disposed within the housing. The drive mechanism includes an electric push rod, and the control mechanism includes a control board located above the electric push rod. A spring return mechanism connected to the electric push rod is disposed outside the housing, and a shift fork is connected to the side of the spring return mechanism away from the housing. The spring return mechanism includes a sliding seat and a telescopic assembly located within the sliding seat, with both ends of the telescopic assembly connected to the electric push rod and the shift fork, respectively. A pressure sensor is also disposed on the sliding seat on the side of the shift fork near the telescopic assembly. Both the electric push rod and the pressure sensor are electrically connected to the control board.

[0008] Furthermore, the power output end of the electric actuator is a push rod; the telescopic assembly includes a slider group connected to the push rod, and a telescopic spring is provided between the slider group and the shift fork rod.

[0009] Furthermore, the sliding seat has a receiving groove with an opening facing the housing. The bottom wall of the receiving groove has a connecting through hole. The shift fork rod is movably connected to the sliding seat through the connecting through hole. The shift fork rod extends from the connecting through hole into the receiving groove and is connected to the telescopic spring.

[0010] Furthermore, the pressure sensor is placed on the shift fork and located at the bottom of the receiving groove, with the end of the telescopic spring away from the housing abutting against the pressure sensor.

[0011] Furthermore, the sliding seat has multiple sliding grooves circumferentially formed at one end near the housing; the slider assembly includes a sliding block and a fixed pin that can slide axially within the sliding groove along the spring return mechanism, the fixed pin being located between the push rod and the sliding block and the sliding block being connected to the fixed pin; the outer diameter of the sliding block is not greater than the inner diameter of the receiving groove, and the outer diameter of the fixed pin is greater than the outer diameter of the sliding seat.

[0012] Furthermore, threaded holes are provided on the sliding block and the push rod respectively, and a smooth hole is provided on the fixing pin. A fastening screw is provided in the threaded hole and the sliding block and the push rod are connected by the fastening screw. The fixing pin is sleeved on the screw rod of the fastening screw.

[0013] Furthermore, the connecting through hole is a threaded hole structure, and the shift fork includes a threaded rod body; the shift fork is provided with a double locking nut threadedly connected to the threaded rod body on the outside of the sliding seat; and a rear cover is provided at the end of the housing away from the shift fork.

[0014] Furthermore, an electrical connector is provided on the housing, and the control board is powered by the electrical connector; the control board includes an embedded microcontroller control system, which includes a PWM drive module, a pressure signal acquisition module, a bus communication module, a current overload detection module, and a protection circuit module.

[0015] A method for controlling the execution of an electronically controlled gear shifting actuator for a special engineering vehicle, wherein the special engineering vehicle includes a side transmission box, and the side transmission box includes a shift lever, a splined shaft, and a shift fork. The shift lever is connected to the shift fork via the splined shaft. The method includes the following steps:

[0016] S1: The electronically controlled shift actuator is initially installed. The shift fork is in the retracted state, and the shift fork pulls the shift lever, so that the vehicle side transmission box is in the driving spur gear meshing state.

[0017] S2: The control board receives CAN bus control commands from the engineering vehicle's gear shifting control system and pressure signals from the pressure sensor in real time.

[0018] When the embedded microcontroller control system receives a command to switch bulldozer gears, the control board drives the electric push rod to work. The push rod of the electric push rod drives the sliding block to extend. The sliding block compresses the telescopic spring and applies pressure to the pressure sensor. The reaction force of the telescopic spring pushes the sliding seat and shift fork rod to extend away from the housing, thereby pulling the rotation angle of the shift lever. The shift lever transmits torque through the spline shaft, driving the shift fork in the side transmission box to move.

[0019] Furthermore, the control board in S2 monitors the pressure value of the pressure sensor in real time, as detailed below:

[0020] When the detected pressure value is within the rated thrust range, the control board controls the electric push rod to move at the current speed until it reaches the end stroke position. The control board then controls the electric push rod to stop working. If the pressure value detected by the control board in real time decreases to the pre-pressure value, the control board determines that the bulldozing gear meshing is complete and sends a bulldozing gear switch to position signal to the system.

[0021] When the pressure value detected by the control board in real time is greater than the rated thrust, the control board reduces the operating voltage supplied to the electric push rod through PWM pulse width modulation, slows down the speed and thus reduces the pressure on the telescopic spring, thereby controlling the pushing force on the shift arm.

[0022] When the pressure value detected by the control board in real time reaches the calibrated stall force, the control board immediately controls the electric push rod to stop working. At this time, the reaction force of the telescopic spring continues to be applied to the shift lever. When the spur gear in the side transmission box completes the alignment, the shift fork rod continues to extend under the action of the telescopic spring. The output pressure value of the pressure sensor decreases to the rated thrust range, and the control board will control the electric push rod to continue to extend until the bulldozing condition gear meshing is completed.

[0023] When the control board receives the system's command to switch driving gears, it controls the electric push rod to retract. The push rod of the electric push rod drives the sliding block to move. At this time, the fixed pin drives the sliding seat and shift fork rod to retract synchronously through the sliding groove. At the same time, it drives the shift lever to rotate in the opposite direction. The shift lever transmits torque through the spline shaft, which drives the shift fork in the side transmission box to switch the spur gear to the driving gear.

[0024] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0025] 1. The electronically controlled shifting actuator in this invention adopts control logic based on the pressure detection of the recoil spring. By adjusting the voltage supplied to the electric push rod through PWM, the traveling speed of the electric push rod can be adjusted, thereby realizing the control of the driving force of the external load. This can effectively solve the problem of the electric push rod motor stalling due to excessive external load, and greatly improve the reliability of operation.

[0026] 2. In the process of pushing the spur gears to mesh, if the electric push rod encounters a tooth-pinching situation, the electric push rod can be controlled to stop. During the alignment process of the spur gears, the spring return mechanism continuously outputs the pushing force, and after alignment, the electric push rod restarts until it extends to the correct position.

[0027] 3. The electronically controlled shifting actuator in this invention adopts a composite control mode based on pressure signal and electric push rod extension and retraction limit switch signal, which can be extended to many similar occasions and has strong versatility. Attached Figure Description

[0028] Figure 1 This is a three-dimensional structural schematic diagram of the electronically controlled gear shifting actuator provided according to an embodiment of the present invention;

[0029] Figure 2 This is a cross-sectional view of an electronically controlled gear shifting actuator provided according to an embodiment of the present invention;

[0030] Figure 3 This is an installation diagram of an electronically controlled gear shifting actuator provided according to an embodiment of the present invention (A shows the gear shifting actuator).

[0031] The reference numerals in the accompanying drawings include: housing 1, electrical connector 2, spring return mechanism 3, shift fork lever 4, electric push rod 5, control board 6, fastening screw 7, pressure sensor 8, push rod 9, telescopic spring 10, sliding groove 11, sliding block 12, fixing pin 13, double locking nut 14, rear cover 15, shift lever arm 16, spline shaft 17, sliding seat 18, groove bottom 19, bottom wall 20, receiving groove 21. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-3The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof.

[0033] An electronically controlled gear shifting actuator for a special engineering vehicle, such as Figure 3 As shown, the special engineering vehicle includes a side transmission box, which contains a shift lever 16, a splined shaft 17, and a shift fork. The shift lever is connected to the shift fork via the splined shaft 17. The electronically controlled shift actuator is as follows: Figure 1 , Figure 2 As shown, the device includes a housing 1 and a drive mechanism and a control mechanism disposed within the housing 1. The drive mechanism includes an electric push rod 5, and the control mechanism includes a control board 6 located above the electric push rod 5. An electrical connector 2 is disposed on the housing 1. The electrical connector 2 is used to supply power to the control board 6, control signals, input pressure signals, and output feedback signals. The control board 6 contains an embedded microcontroller control system, which includes a PWM drive module, a pressure signal acquisition module, a bus communication module, a current overload detection module, and a protection circuit module.

[0034] The housing 1 is provided with a spring return mechanism 3 connected to the electric push rod 5. The side of the spring return mechanism 3 away from the housing 1 is connected to the shift fork 4. The spring return mechanism 3 includes a sliding seat 18 and a telescopic component located in the sliding seat 18. The two ends of the telescopic component are connected to the electric push rod 5 and the shift fork 4 respectively. The sliding seat 18 is also provided with a pressure sensor 8 located on the side of the shift fork 4 near the telescopic component. The electric push rod 5 and the pressure sensor 8 are both electrically connected to the control board 6.

[0035] The power output end of the electric push rod 5 is the push rod 9. The telescopic assembly includes a slider group connected to the push rod 9. A telescopic spring 10 is provided between the slider group and the shift fork 4. The sliding seat 18 has a receiving groove 21 with an opening facing the housing 1. The pressure sensor 8 is placed on the shift fork 4 and located at the bottom 19 of the receiving groove 21. The end of the telescopic spring 10 away from the housing 1 abuts against the pressure sensor 8. When the push rod 9 applies pressure to the telescopic spring 10, the telescopic spring 10 can further transmit the pressure to the pressure sensor 8.

[0036] The bottom wall 20 of the receiving groove 21 is provided with a connecting through hole. The shift fork 4 and the sliding seat 18 are movably connected through the connecting through hole. The shift fork 4 extends into the receiving groove 21 from the connecting through hole and is connected to the telescopic spring 10. The connecting through hole is a threaded hole structure. The shift fork 4 includes a threaded rod body. The shift fork 4 is provided with a double locking nut 14 threadedly connected to the threaded rod body on the outside of the sliding seat 18. The length of the shift fork 4 extending to the outside of the bottom wall 20 can be adjusted and it is fastened by the double locking nut 14. The double locking nut 14 has good vibration resistance, high safety, is easy to maintain, can improve the friction relaxation effect, and has strong durability and adaptability.

[0037] Multiple sliding grooves 11 are provided circumferentially on one end of the sliding seat 18 near the housing 1. The sliding grooves 11 are U-shaped grooves. The slider assembly includes a sliding block 12 and a fixing pin 13 that can slide along the axial direction of the spring return mechanism 3 in the sliding groove 11. The fixing pin 13 is located between the top rod 9 and the sliding block 12, and the sliding block 12 is connected to the fixing pin 13. The outer diameter of the sliding block 12 is not greater than the inner diameter of the receiving groove 21. The outer diameter of the fixing pin 13 is greater than the outer diameter of the sliding seat 18. The fixing pin 13 can extend and retract in the sliding groove 11. The fixing pin 13 can extend and retract in the receiving groove 21 with the sliding block 12.

[0038] The sliding block 12 and the push rod 9 are respectively provided with threaded holes, and the fixing pin 13 is provided with a smooth hole. The threaded hole is provided with a fastening screw 7, which connects the sliding block 12 and the push rod 9. The fixing pin 13 is sleeved on the screw of the fastening screw 7. The end of the housing 1 away from the shift fork is provided with a rear cover 15, which makes it easy to open the rear cover 15 to replace, disassemble and repair the various parts inside the housing 1.

[0039] A method for controlling the execution of an electronically controlled gear shifting actuator for a special engineering vehicle, comprising the following steps:

[0040] S1: Initial installation of the electronically controlled shift actuator. The shift fork lever 4 is in the fully retracted state. Since the shift lever arm 16 is connected to the shift fork inside the side reducer through the spline shaft 17, the shift fork lever 4 pulls the shift lever arm 16, so that the vehicle side transmission box is in the driving spur gear meshing state.

[0041] S2: Control board 6 receives CAN bus control commands from the engineering vehicle shift control system and pressure signals from pressure sensor 8 in real time.

[0042] When the embedded microcontroller control system receives the command to switch bulldozer gears, the control board 6 drives the electric push rod 5 to work. The push rod 9 of the electric push rod 5 drives the sliding block 12 to extend. The sliding block 12 compresses the telescopic spring 10 and applies pressure to the pressure sensor 8. The reaction force of the telescopic spring 10 pushes the sliding seat 18 and the shift fork rod 4 to extend away from the housing 1, thereby pulling the rotation angle of the shift lever 16. The shift lever 16 transmits torque through the spline shaft 17, driving the shift fork in the side transmission box to move.

[0043] Control board 6 monitors the pressure value of pressure sensor 8 in real time, as detailed below:

[0044] When the detected pressure value is within the rated thrust range, the control board 6 controls the electric push rod 5 to move at the current speed until it reaches the end stroke position. The control board 6 then controls the electric push rod 5 to stop working. If the pressure value detected by the control board 6 in real time decreases to the pre-pressure value, the control board 6 determines that the bulldozing gear meshing is complete and sends a bulldozing gear switch to position signal to the system.

[0045] When the pressure value detected by the control board 6 in real time is greater than the rated thrust, the control board 6 reduces the operating voltage supplied to the electric push rod 5 through PWM pulse width modulation, slows down the speed and reduces the pressure on the telescopic spring 10, thereby controlling the pushing force on the shift lever 16 to avoid excessive gear meshing impact, which could lead to shifting impact and gear damage.

[0046] When the pressure value detected by the control board 6 in real time reaches the calibrated stall force, the control board 6 immediately controls the electric push rod 5 to stop working. Since the electric push rod 5 and the shift fork 4 are elastically connected by the telescopic spring 10, the electric push rod 5 will not stall. At this time, the reaction force of the telescopic spring 10 continues to be applied to the shift lever 16. When the spur gear in the side transmission box completes the alignment, the shift fork 4 continues to extend under the action of the telescopic spring 10. The output pressure value of the pressure sensor 8 decreases to the rated thrust range. The control board 6 will control the electric push rod 5 to continue to extend until the gear meshing of the bulldozing condition is determined to be completed.

[0047] When the control board 6 receives the system's command to switch driving gears, it controls the electric push rod 5 to retract. The push rod 9 of the electric push rod 5 drives the sliding block 12 to move. At this time, the fixed pin 13 drives the sliding seat 18 and the shift fork rod 4 to retract synchronously through the sliding groove 11. At the same time, it drives the shift lever 16 to rotate in the opposite direction. The shift lever 16 transmits torque through the spline shaft 17, which drives the shift fork in the side transmission box to switch the straight gear to the driving gear.

[0048] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. An electrically controlled shift actuator for a specialty engineered vehicle, characterized by, The utility model relates to a kind of spring return mechanism and control mechanism of driving mechanism, including shell (1) and being arranged in shell (1), driving mechanism includes electric push rod (5), control mechanism includes control board card (6) above electric push rod (5);Shell (1) is externally provided with spring return mechanism (3) connected with electric push rod (5), spring return mechanism (3) is connected with shift lever (4) on the side away from shell (1);Spring return mechanism (3) includes sliding seat (18) and telescopic component in sliding seat (18), the both ends of telescopic component are connected with electric push rod (5) and shift lever (4) respectively;Sliding seat (18) is also provided with pressure sensor (8) on the side of shift lever (4) close to telescopic component;Electric push rod (5) and pressure sensor (8) are electrically connected with control board card (6);The power output end of electric push rod (5) is top rod (9);Telescopic component includes sliding block group connected with top rod (9), and sliding block group is equipped with telescopic spring (10) between shift lever (4);Sliding seat (18) is opened with the accommodating groove (21) of opening towards shell (1), the bottom wall (20) of accommodating groove (21) is equipped with connecting through hole, shift lever (4) is movably connected with sliding seat (18) by connecting through hole, shift lever (4) is inserted into accommodating groove (21) from connecting through hole and is connected with telescopic spring (10);The one end of sliding seat (18) close to shell (1) is opened with multiple sliding grooves (11) along circumference direction;Sliding block group includes sliding block (12) and fixed pin (13) that can slide in the axial direction of spring return mechanism (3) in sliding groove (11), fixed pin (13) is between top rod (9) and sliding block (12) and sliding block (12) is connected on fixed pin (13);The outer diameter of sliding block (12) is not greater than the inner diameter of accommodating groove (21), and the outer diameter of fixed pin (13) is greater than the outer diameter of sliding seat (18);Threaded hole is opened on the sliding block (12) and top rod (9) respectively, and light hole is opened on fixed pin (13), threaded hole is equipped with fastening screw (7) and sliding block (12) and top rod (9) are connected by fastening screw (7), and fixed pin (13) is sleeved on the screw rod of fastening screw (7).

2. The electrically controlled shift actuator for a special use engineering vehicle according to claim 1, characterized by, The pressure sensor (8) is placed on the shift lever (4) and located at the groove bottom (19) of the accommodating groove (21), and the end of the telescopic spring (10) away from the shell (1) abuts on the pressure sensor (8).

3. The electrically controlled shift actuator for a special use engineering vehicle of claim 1 wherein, The connecting through hole is a threaded hole structure, and the shift lever (4) includes a threaded rod body; The double locking nuts (14) are screwed on the threaded rod body outside the sliding seat (18) on the shift lever (4); The shell (1) away from the shift lever is provided with a rear cover (15).

4. The electrically controlled shift actuator for a special use engineering vehicle of claim 1, wherein The shell (1) is provided with an electrical connector (2), and the control board card (6) is powered by the electrical connector (2); The control board card (6) contains an embedded single-chip microcomputer control system, which includes a PWM drive module, a pressure signal acquisition module, a bus communication module, a current overload detection module and a protection circuit module.

5. A method of performing control of an electrically controlled gear shift actuator of a special engineering vehicle, which is provided with a side transmission case including a shift lever (16), a spline shaft (17) and a shift fork therein, and the shift lever (16) is connected to the shift fork through the spline shaft (17), wherein the electrically controlled gear shift actuator of the special engineering vehicle according to claim 4 is used to perform control, characterized in that, The utility model relates to a kind of spring return mechanism and control mechanism of driving mechanism, including shell (1) and being arranged in shell (1), driving mechanism includes electric push rod (5), control mechanism includes control board card (6) above electric push rod (5);Shell (1) is externally provided with spring return mechanism (3) connected with electric push rod (5), spring return mechanism (3) is connected with shift lever (4) on the side away from shell (1);Spring return mechanism (3) includes sliding seat (18) and telescopic component in sliding seat (18), the both ends of telescopic component are connected with electric push rod (5) and shift lever (4) respectively;Sliding seat (18) is also provided with pressure sensor (8) on the side of shift lever (4) close to telescopic component;Electric push rod (5) and pressure sensor (8) are electrically connected with control board card (6);The power output end of electric push rod (5) is top rod (9);Telescopic component includes sliding block group connected with top rod (9), and sliding block group is equipped with telescopic spring (10) between shift lever (4);Sliding seat (18) is opened with the accommodating groove (21) of opening towards shell (1), the bottom wall (20) of accommodating groove (21) is equipped with connecting through hole, shift lever (4) is movably connected with sliding seat (18) by connecting through hole, shift lever (4) is inserted into accommodating groove (21) from connecting through hole and is connected with telescopic spring (10);The one end of sliding seat (18) close to shell (1) is opened with multiple sliding grooves (11) along circumference direction;Sliding block group includes sliding block (12) and fixed pin (13) that can slide in the axial direction of spring return mechanism (3) in sliding groove (11), fixed pin (13) is between top rod (9) and sliding block (12) and sliding block (12) is connected on fixed pin (13);The outer diameter of sliding block (12) is not greater than the inner diameter of accommodating groove (21), and the outer diameter of fixed pin (13) is greater than the outer diameter of sliding seat (18);Threaded hole is opened on the sliding block (12) and top rod (9) respectively, and light hole is opened on fixed pin (13), threaded hole is equipped with fastening screw (7) and sliding block (12) and top rod (9) are connected by fastening screw (7), and fixed pin (13) is sleeved on the screw rod of fastening screw (7). S1: The initial installation of the electric control gear shifting actuator, the shift fork rod (4) is in the retracted state, the shift fork rod (4) holds the shift pull arm (16), so that the vehicle side transmission case is in the driving straight tooth pair meshing state; S2: The control board card (6) receives the CAN bus control command issued by the engineering vehicle gear shifting control system and the pressure signal sent by the pressure sensor (8) in real time; When receiving the switching bulldozing gear command issued by the embedded single-chip microcomputer control system, the control board card (6) drives the electric push rod (5) to work, the top rod (9) of the electric push rod (5) drives the sliding block (12) to extend, the sliding block (12) compresses the extension spring (10) and exerts pressure on the pressure sensor (8), the counterforce of the extension spring (10) drives the sliding seat (18) and the shift fork rod (4) to extend towards the side away from the shell (1), thereby pulling the rotation angle of the shift pull arm (16), the shift pull arm (16) transmits torque through the spline shaft (17), and drives the shift fork in the side transmission case to move; In S2, the control board card (6) detects the pressure value of the pressure sensor (8) in real time, and the specific conditions are as follows: When the detected pressure value is in the rated thrust range, the control board card (6) controls the electric push rod (5) to act according to the current speed until it works to the in-place stroke position, the control board card (6) controls the electric push rod (5) to stop working, and if the real-time detected pressure value of the control board card (6) decreases to the pre-pressing value, the control board card (6) judges that the bulldozing working condition gear meshing is completed, and sends a bulldozing gear switching in-place signal to the system; When the real-time detected pressure value of the control board card (6) is greater than the rated thrust, the control board card (6) reduces the operating voltage supplied to the electric push rod (5) through PWM pulse width modulation, slows down the speed, and thereby reduces the pressure on the extension spring (10), so as to control the pushing force on the shift pull arm (16); When the real-time detected pressure value of the control board card (6) reaches the rated locked-rotor force, the control board card (6) immediately controls the electric push rod (5) to stop working, at this time the counterforce of the extension spring (10) continuously acts on the shift pull arm (16), when the straight tooth pair in the side transmission case is centered, the shift fork rod (4) continues to extend under the action of the extension spring (10), the output pressure value of the pressure sensor (8) decreases to the rated thrust range, and the control board card (6) controls the electric push rod (5) to continue to extend until it is judged that the bulldozing working condition gear meshing is completed; When the control board card (6) receives the switching driving gear command issued by the system, the electric push rod (5) is retracted, the top rod (9) of the electric push rod (5) drives the sliding block (12) to move, at this time the fixed pin (13) drives the sliding seat (18) and the shift fork rod (4) to retract synchronously through the sliding groove (11), and drives the shift pull arm (16) to rotate in the opposite direction, the shift pull arm (16) transmits torque through the spline shaft (17), and drives the shift fork in the side transmission case to switch the straight tooth pair to the driving gear.

Images