Motion control system, method for a skidder and skidder

Abstract

The embodiment of the application provides a motion control system, a method and a skid steer loader for the skid steer loader, and belongs to the field of hydraulic control. The system comprises two control devices, and the control device comprises: a hydraulic pump comprising a first inlet and outlet and a second inlet and outlet, wherein the hydraulic pump is connected with an oil tank; a first electromagnetic reversing valve connected with the first inlet and outlet, wherein the first electromagnetic reversing valve comprises a first outlet position and a second outlet position; a walking hydraulic motor comprising a third inlet and outlet and a fourth inlet and outlet, wherein the third inlet and outlet is connected with the first outlet position, and the fourth inlet and outlet is connected with the second inlet and outlet; a synchronous hydraulic motor connected with the second outlet position; the rotating shafts of the synchronous hydraulic motors of the two control devices are fixedly connected; the system further comprises a controller for outputting a first control signal to the first electromagnetic reversing valve to control the first electromagnetic reversing valve to reverse to the second outlet position; an engine connected with the hydraulic pump and the controller and used for driving the hydraulic pump.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control, and more specifically to a motion control system, method, and skid steer for a skid steer. Background Technology

[0002] Skid steer loaders are mainly used in infrastructure construction, industrial applications, urban streets, residential areas, and barns, with their main feature being their ability to enter and exit narrow spaces. However, existing skid steer loaders primarily use mechanical or pure hydraulic control methods, which cannot maintain high-precision straight-line movement. Real-time manual operation is required during movement, and this high level of manual labor significantly impacts the loader's efficiency and operator comfort. Summary of the Invention

[0003] The purpose of this invention is to overcome the problem that existing skid steer motion control systems cannot guarantee high-precision linear movement of the skid steer, and to provide a motion control system, method, and skid steer for the skid steer.

[0004] The first aspect of this application provides a motion control system for a skid steer machine, characterized in that the system includes two control devices, each comprising:

[0005] The hydraulic pump includes a first inlet / outlet and a second inlet / outlet, and is connected to the oil tank.

[0006] The first electromagnetic reversing valve is connected to the first inlet and outlet oil ports. The first electromagnetic reversing valve includes a first outlet oil position and a second outlet oil position.

[0007] The travel hydraulic motor includes a third oil inlet / outlet and a fourth oil inlet / outlet. The third oil inlet / outlet is connected to the first oil outlet, and the fourth oil inlet / outlet is connected to the second oil inlet / outlet.

[0008] A synchronous hydraulic motor is connected to the second oil outlet position;

[0009] The shafts of the synchronous hydraulic motors of the two control devices are fixedly connected;

[0010] The system also includes a controller for outputting a first control signal to the first solenoid directional valve to control the first solenoid directional valve to switch to the second oil outlet position;

[0011] The engine, along with the hydraulic pump and controller, is connected to drive the hydraulic pump.

[0012] In one embodiment of this application, the hydraulic pump is a variable displacement pump, and the control device further includes:

[0013] The variable piston has its piston rod connected to the movable swashplate of the hydraulic pump.

[0014] The three-position four-way solenoid valve is connected to the oil tank and to the left and right cylinders of the variable piston, respectively. It is used to receive the second control signal output by the controller. The second control signal is also output to the engine to control the engine speed and control the position of the three-position four-way solenoid valve so that the flow of the hydraulic pump remains constant.

[0015] The three-position four-way solenoid valve is connected to the oil tank via a replenishing pump.

[0016] In one embodiment of this application, the system further includes a speed sensor for acquiring the real-time speed of the engine, and the controller is also used to acquire the real-time speed and, when the real-time speed is greater than a preset threshold, send an overload signal to a three-position four-way solenoid valve to control the three-position four-way solenoid valve to change position, thereby reducing the displacement of the hydraulic pump.

[0017] In one embodiment of this application, the control device further includes:

[0018] The second electromagnetic reversing valve is connected to the first inlet and outlet ports. The second electromagnetic reversing valve includes a third outlet position. The second electromagnetic reversing valve is used to receive a third control signal output by the controller. The third control signal is used to control the second electromagnetic reversing valve to switch to the third outlet position.

[0019] The second oil inlet / outlet is connected to the third oil outlet.

[0020] The damper is connected between the second oil inlet / outlet and the third oil outlet.

[0021] In one embodiment of this application, the control device further includes:

[0022] The flushing valve is connected in parallel with the travel hydraulic motor and is connected to the oil tank through an overflow valve.

[0023] In one embodiment of this application, the control device further includes:

[0024] The first pressure-stabilizing overflow valve has its inlet connected to the first inlet and outlet, and its outlet connected to the oil tank.

[0025] The second pressure-stabilizing overflow valve has its inlet connected to the second inlet / outlet, and its outlet connected to the oil tank.

[0026] The first check valve, connected in parallel with the first pressure-stabilizing relief valve, supplies power to the travel hydraulic motor;

[0027] The second check valve, connected in parallel with the second pressure-stabilizing relief valve, supplies power to the travel hydraulic motor.

[0028] Both the first and second check valves are connected to the replenishing pump, which is connected to the oil tank.

[0029] The second aspect of this application provides a skid steer machine, including the motion control system for the skid steer machine provided in the first aspect of this application.

[0030] A third aspect of this application provides a motion control method for a skid steer, characterized in that it is applied to the motion control system for a skid steer provided in the first aspect of this application, and the method includes:

[0031] The controller outputs a first control signal to the first solenoid directional valve to control the first solenoid directional valve to switch to the second oil outlet position.

[0032] In one embodiment of this application, the control device further includes a variable piston, the piston rod of which is connected to the movable swashplate of the hydraulic pump; a three-position four-way solenoid valve, which is connected to the oil tank and to the left and right cylinders of the variable piston respectively; the three-position four-way solenoid valve is connected to the oil tank via a replenishing pump; and the method further includes:

[0033] The second control signal is received from the controller via a three-position four-way solenoid valve. This second control signal is also output to the engine to control the engine speed and the position of the three-position four-way solenoid valve, so that the flow rate of the hydraulic pump remains constant.

[0034] In one embodiment of this application, the system further includes a speed sensor for acquiring real-time engine speed, and the method further includes:

[0035] The controller obtains the real-time speed. When the real-time speed is greater than the preset threshold, an overload signal is sent to the three-position four-way solenoid valve to control the three-position four-way solenoid valve to change position, thereby reducing the displacement of the hydraulic pump.

[0036] In one embodiment of this application, the control device further includes a second solenoid directional valve connected to the first inlet / outlet oil port. The second solenoid directional valve includes a third outlet oil position, with the second inlet / outlet oil port connected to the third outlet oil position. A damping mechanism is connected between the second inlet / outlet oil port and the third outlet oil position. The method further includes:

[0037] The second solenoid directional valve receives a third control signal output from the controller, wherein the third control signal is used to control the second solenoid directional valve to switch to the third oil outlet position.

[0038] The fourth aspect of this application provides a machine-readable storage medium, characterized in that the machine-readable storage medium stores instructions that, when executed by a processor, cause the processor to implement the motion control method for a skid machine provided in the third aspect of this application.

[0039] By utilizing the above technical solution and the electro-hydraulic control principle, the circulating oil between the two hydraulic pumps and the two travel motors is controlled by the switching of the electromagnetic directional valve. This ensures that the flow rate of hydraulic oil output from or input to the two travel motors is equal, which in turn ensures that the speed of the two travel motors is equal. This enables the skid steer machine to achieve high-precision linear movement and reduces the intensity of manual operation.

[0040] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0041] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0042] Figure 1 The schematic diagram illustrates a structural schematic of a motion control system for a skid steer according to an embodiment of this application;

[0043] Figure 2 for Figure 1 A magnified view of part X in the middle;

[0044] Figure 3 for Figure 1 A magnified view of the Y-section in the middle;

[0045] Figure 4 The schematic diagram illustrates a flow chart of a skid steer machine's straight-line travel mode according to an embodiment of this application;

[0046] Figure 5 The schematic diagram illustrates a flow chart of a constant speed travel mode of a skid steer according to an embodiment of this application. Detailed Implementation

[0047] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0048] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and reversal of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0049] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0050] Figure 1 This illustration schematically depicts a motion control system for a skid steer according to an embodiment of this application. Figure 2 for Figure 1 A magnified view of part X in the middle. Figure 3 for Figure 1 Please also refer to the enlarged view of the Y-section in the middle. Figure 1 , Figure 2 as well as Figure 3 In one embodiment of this application, a motion control system for a skid steer is provided, the system including two control devices.

[0051] The control device may include: a hydraulic pump 1, including a first oil inlet / outlet 2 and a second oil inlet / outlet 3, and the hydraulic pump 1 is connected to an oil tank;

[0052] The first electromagnetic reversing valve 4 is connected to the first inlet and outlet oil port 2. The first electromagnetic reversing valve 4 includes a first outlet oil position 5 and a second outlet oil position 6.

[0053] The walking hydraulic motor 7 includes a third oil inlet / outlet 8 and a fourth oil inlet / outlet 9. The third oil inlet / outlet 8 is connected to the first oil outlet 5, and the fourth oil inlet / outlet 9 is connected to the second oil inlet / outlet 3.

[0054] Synchronous hydraulic motor 10 is connected to the second oil outlet 6;

[0055] The rotating shafts of the synchronous hydraulic motors 10 of the two control devices are fixedly connected;

[0056] The system may also include a controller 11 for outputting a first control signal to the first solenoid directional valve 4 to control the first solenoid directional valve 4 to switch to the second oil outlet position 6.

[0057] The engine 12 is connected to both the hydraulic pump 1 and the controller 11 and is used to drive the hydraulic pump 1.

[0058] The motion control system provided in this embodiment is a closed-loop hydraulic circuit based on electro-hydraulic control, including two control devices that control the torque output of the left and right sides of the skid steer, respectively, i.e., control the speed of the left and right wheels of the skid steer. The control logic and structure of the two control devices are consistent. Therefore, this embodiment only uses one control device as an example for discussion, and the control logic and structure of the other control device will not be described in detail.

[0059] Each control device includes a hydraulic pump 1 that converts mechanical energy into hydraulic energy and a travel hydraulic motor 7 that converts hydraulic energy into mechanical energy, i.e., outputting the mechanical energy required for the skid steer to move. The hydraulic pump 1 includes a first inlet / outlet port 2 and a second inlet / outlet port 3, and the travel hydraulic motor 7 includes a third inlet / outlet port 8 and a fourth inlet / outlet port 9. Because the circuit is closed, the first inlet / outlet port 2 of the hydraulic pump 1 is connected to the third inlet / outlet port 8 of the travel hydraulic motor 7, and the fourth inlet / outlet port 9 of the travel hydraulic motor 7 is connected to the second inlet / outlet port 3 of the hydraulic pump 1. For example, hydraulic oil flows from the first inlet / outlet port 2 into the third inlet / outlet port 8, and then flows back from the fourth inlet / outlet port 9 into the second inlet / outlet port 3, causing the travel hydraulic motor 7 to rotate and the skid steer to move forward; hydraulic oil flows from the fourth inlet / outlet port 9 into the second inlet / outlet port 3, and then flows back from the third inlet / outlet port 8 into the first inlet / outlet port 2, causing the travel hydraulic motor 7 to reverse and the skid steer to move backward.

[0060] The first oil inlet / outlet 2 is also connected to the first solenoid directional valve 4, which includes a first oil outlet position 5 and a second oil outlet position 6. When energized, the first solenoid directional valve 4 can switch to the second oil outlet position 6.

[0061] The motion control system provided in this embodiment ensures that the linear movement of the skid steer machine relies on two hydraulic motors that are fixedly connected to two rotating shafts, namely the synchronous hydraulic motors 10 in the two devices. Since the rotating shafts of the two synchronous hydraulic motors 10 are fixedly connected, their rotation speeds are always consistent, and the hydraulic oil flow through the two synchronous hydraulic motors 10 is also always consistent.

[0062] Whether the hydraulic fluid flowing out of or into the first inlet / outlet 2 passes through the synchronous hydraulic motor 10 is determined by the first solenoid directional valve 4. When the first outlet position 5 is connected to the oil circuit, the third inlet / outlet 8 is directly connected to the first inlet / outlet 2, and the hydraulic fluid flowing out of the first inlet / outlet 2 flows directly into the third inlet / outlet 8, and the hydraulic fluid flowing out of the third inlet / outlet 8 flows directly into the first inlet / outlet 2. When the first solenoid directional valve 4 is energized, the second outlet position 6 is connected to the oil circuit, and the third inlet / outlet 8 passes through the traveling hydraulic motor 10. The hydraulic oil flowing from the first inlet / outlet 2 is connected to the first inlet / outlet 2. The hydraulic oil flowing out from the first inlet / outlet 2 flows into the third inlet / outlet 8 through the travel hydraulic motor 7. The hydraulic oil flowing out from the third inlet / outlet 8 flows into the first inlet / outlet 2 through the travel hydraulic motor 7. Because the hydraulic oil flow rate through the two synchronous hydraulic motors 10 is always consistent, the flow rate of hydraulic oil flowing into or out of the travel hydraulic motor 7 is also consistent. This ensures that the rotation speed of the two travel hydraulic motors 7 is the same and the speed of the left and right wheels is the same. The skid steer can achieve high-precision linear travel.

[0063] The motion control system provided in this embodiment also includes a controller 11, which is electrically connected to the first electromagnetic reversing valve 4. When the controller 11 outputs a first control signal to the first electromagnetic reversing valve 4, the first electromagnetic reversing valve 4 is energized and reverses to the second oil outlet position 6, so that the third oil inlet / outlet 8 is connected to the first oil inlet / outlet 2 through the walking hydraulic motor 7.

[0064] The motion control system provided in this embodiment also includes an engine 12, which is connected to both the hydraulic pump 1 and the controller 11, and can drive the hydraulic pump 1 according to the control signal output by the controller 11.

[0065] In one embodiment of this application, the hydraulic pump 1 is a variable displacement pump, and the control device further includes:

[0066] Variable piston 13, the piston rod of variable piston 13 is connected to the movable swashplate of hydraulic pump 1;

[0067] The three-position four-way solenoid valve 14 is connected to the oil tank and to the left and right cylinders of the variable piston 13 respectively. It is used to receive the second control signal output by the controller 11. The second control signal is also output to the engine 12 to control the speed of the engine 12 and control the position of the three-position four-way solenoid valve 14 so that the flow of the hydraulic pump 1 remains constant.

[0068] The three-position four-way solenoid valve 14 is connected to the oil tank via the oil replenishment pump 15.

[0069] The hydraulic pump 1, acting as a variable displacement pump, includes a movable swashplate. The displacement of the hydraulic pump 1 is adjusted by the oscillation of the movable swashplate. The piston rod of the variable piston 13 is connected to the movable swashplate, and the movement of the piston rod directly drives the oscillation of the movable swashplate. The left and right cylinders of the variable piston 13 are respectively connected to a three-position four-way solenoid valve 14 via oil circuits. The three-position four-way solenoid valve 14 is connected to an oil tank and also to a replenishing pump 15 connected to the oil tank. When the three-position four-way solenoid valve 14 is energized and changes position, it causes the piston rod of the variable piston 13 to move, driving the movable swashplate to oscillate, thereby adjusting the displacement of the hydraulic pump 1.

[0070] When the controller 11 outputs a second control signal to the three-position four-way solenoid valve 14, it also outputs a second control signal to the engine 12. The second control signal controls the speed of the engine 12 and the position of the three-position four-way solenoid valve 14, that is, controls the speed and displacement of the hydraulic pump 1, so that the flow rate of the hydraulic pump 1 remains constant, which ensures that the flow rate of the travel hydraulic motor 7 remains constant, and thus ensures that the speed of the travel hydraulic motor 7 remains constant, so that the left and right wheels can maintain a constant speed.

[0071] In one embodiment of this application, the motion control system may further include a flow sensor 26 for collecting the real-time flow rate of hydraulic oil flowing into or out of the hydraulic pump 1, so as to facilitate flow monitoring by the controller 11.

[0072] In one embodiment of this application, the system further includes a speed sensor 16 for acquiring the real-time speed of the engine 12. The controller 11 is also used to acquire the real-time speed and, if the difference between the real-time speed and the engine 12 speed in the previous measurement cycle is greater than a preset threshold, send an overload signal to the three-position four-way solenoid valve 14 to control the three-position four-way solenoid valve 14 to change position, thereby reducing the displacement of the hydraulic pump 1.

[0073] The speed sensor 16 is electrically or communicatively connected to the controller 11. The controller 11 obtains the real-time speed of the engine 12 through the speed sensor 16. If the difference between the real-time speed and the engine 12 speed in the previous measurement cycle is greater than a preset threshold, the controller 11 determines that the engine 12 is in an overload state, sends an overload signal to the three-position four-way solenoid valve 14, controls the three-position four-way solenoid valve 14 to change position, reduces the displacement of the hydraulic pump 1, avoids engine 12 overload, and provides overload protection for the engine 12.

[0074] In one embodiment of this application, the control device further includes:

[0075] The second electromagnetic reversing valve 17 is connected to the first inlet / outlet port 2. The second electromagnetic reversing valve 17 includes a third outlet position 18. The second electromagnetic reversing valve 17 is used to receive a third control signal output by the controller 11. The third control signal is used to control the second electromagnetic reversing valve 17 to switch to the third outlet position 18.

[0076] The second oil inlet / outlet 3 is connected to the third oil outlet 18;

[0077] Damping 19 is connected between the second oil inlet / outlet 3 and the third oil outlet 18.

[0078] To prevent hydraulic pump 1 from becoming pressurized, the second solenoid directional valve 17 and the damper 19 are connected between the first inlet / outlet port 2 and the second inlet / outlet port 3. When the second solenoid directional valve 17 is energized by the third control signal output by the controller 11, it switches to the third outlet position 18, so that the first inlet / outlet port 2 can be connected to the second inlet / outlet port 3 through the third outlet position 18. When the oil pressure of the hydraulic oil entering or flowing out of the hydraulic pump 1 is greater than that required by the travel hydraulic motor 7, the excess hydraulic oil can flow through the third outlet position 18 to the damper 19 to consume the oil pressure and then flow back to the second inlet / outlet port 3, thereby preventing hydraulic pump 1 from becoming pressurized.

[0079] In one embodiment of this application, the control device further includes:

[0080] The flushing valve 20 is connected in parallel with the travel hydraulic motor 7 and is connected to the oil tank through an overflow valve 21.

[0081] The hydraulic oil flowing out of the travel hydraulic motor 7 is at a high temperature. In order to protect the components in the oil circuit and extend their service life, a flushing valve 20 needs to be connected in parallel to the travel hydraulic motor 7. When the oil pressure of the high-temperature hydraulic oil flowing out of the travel hydraulic motor 7 accumulates to a certain value, the flushing valve 20 changes position according to the high pressure point, so that the high-temperature hydraulic oil can flow from the circuit to the oil tank and mix with the normal temperature oil in the oil tank. The overflow valve 21 connected to the flushing valve 20 plays the role of overflow protection and pressure stabilization.

[0082] In one embodiment of this application, the control device further includes:

[0083] The first pressure-stabilizing overflow valve 22 has its inlet connected to the first inlet / outlet 2 and its outlet connected to the oil tank.

[0084] The second pressure-stabilizing overflow valve 23 has its inlet connected to the second inlet / outlet 3 and its outlet connected to the oil tank.

[0085] The first check valve 24 is connected in parallel with the first pressure-stabilizing relief valve 22 and is connected to the walking hydraulic motor 7.

[0086] The second check valve 25 is connected in parallel with the second pressure-stabilizing relief valve 23 and is connected to the travel hydraulic motor 7.

[0087] Both the first check valve 24 and the second check valve 25 are connected to the replenishing pump 15, which is connected to the oil tank.

[0088] The control device is equipped with pressure-stabilizing relief valves at both the first inlet / outlet 2 and the second inlet / outlet 3, which are connected to the oil tank. The first pressure-stabilizing relief valve 22 and the second pressure-stabilizing relief valve 23 determine the maximum working pressure of the motion control system. When the pressure at the first inlet / outlet 2 and the second inlet / outlet 3 exceeds the preset value of the maximum working pressure, the first pressure-stabilizing relief valve 22 and the second pressure-stabilizing relief valve 23 open, and the hydraulic oil can flow into the oil tank through the first pressure-stabilizing relief valve 22 and the second pressure-stabilizing relief valve 23.

[0089] As a closed hydraulic circuit, the motion control system may experience negative loads at the actuator end, thus requiring oil replenishment to the actuator end. The control device also includes a first check valve 24 and a second check valve 25, which are connected in parallel with the first pressure-stabilizing relief valve 22 and the second pressure-stabilizing relief valve 23, respectively, and are connected to the oil replenishment pump 15, thus connecting to the travel hydraulic motor 7, i.e., to the actuator end, so that the hydraulic oil flowing out of the oil replenishment pump 15 can be guided to the actuator end.

[0090] By utilizing the electro-hydraulic control principle and controlling the switching of the electromagnetic directional valve, the circulating oil between the two hydraulic pumps and the two travel hydraulic motors is ensured to flow through the two coaxially connected synchronous hydraulic motors. This ensures that the flow rate of hydraulic oil output from or input to the two travel hydraulic motors is equal, which in turn ensures that the rotation speed of the two travel hydraulic motors is equal. This enables the skid steer machine to achieve high-precision linear movement and reduces the intensity of manual operation.

[0091] In one embodiment of this application, a skid steer is provided, including the motion control system for the skid steer described in the above embodiments.

[0092] In one embodiment of this application, a motion control method for a skid steer is provided, applied to the motion control system for a skid steer described in the above embodiment, the method comprising:

[0093] The controller 11 outputs a first control signal to the first solenoid directional valve 4 to control the first solenoid directional valve 4 to switch to the second oil outlet position 6.

[0094] The first control signal output by the controller 11 causes the first solenoid directional valve 4 to switch to the second oil level. The first inlet / outlet 2 and the third inlet / outlet 8 are connected through the synchronous hydraulic motor 10. The synchronous hydraulic motor 10 of the two control devices ensures that the hydraulic oil flow into or out of the two travel hydraulic motors 7 is consistent, that is, it ensures that the left and right wheels of the skid steer can maintain the same speed and achieve high-precision linear travel.

[0095] In one embodiment of this application, the control device further includes a variable piston 13, the piston rod of which is connected to the movable swashplate of the hydraulic pump 1; a three-position four-way solenoid valve 14, which is connected to an oil tank and to the left and right cylinders of the variable piston 13 respectively; and the three-position four-way solenoid valve 14 is connected to the oil tank via a replenishing pump 15. The method further includes:

[0096] The second control signal is received by the controller 11 through the three-position four-way solenoid valve 14. The second control signal is also output to the engine 12 to control the speed of the engine 12 and control the position of the three-position four-way solenoid valve 14 so that the flow rate of the hydraulic pump 1 remains constant.

[0097] When the controller 11 outputs the second control signal to the engine 12 and the three-position four-way solenoid valve 14, it controls the three-position four-way solenoid valve 14 to change position, that is, to control the displacement of the hydraulic pump 1 and the speed of the engine 12, so that the product of the speed of the engine 12 and the displacement of the hydraulic pump 1—the flow rate of the hydraulic pump 1—remains unchanged, that is, the flow rate entering the travel hydraulic motor 7 remains unchanged, so that both the left and right wheels can maintain a constant speed.

[0098] In one embodiment of this application, the system further includes a speed sensor 16 for acquiring the real-time speed of the engine 12, and the method further includes:

[0099] The controller 11 obtains the real-time speed. If the difference between the real-time speed and the engine 12 speed in the previous measurement cycle is greater than a preset threshold, an overload signal is sent to the three-position four-way solenoid valve 14 to control the three-position four-way solenoid valve 14 to change position, thereby reducing the displacement of the hydraulic pump 1.

[0100] The controller 11 will overload the engine 12 based on the real-time speed of the engine 12. When the difference between the real-time speed and the engine 12 speed in the previous measurement cycle is greater than the preset threshold, it can be determined that the engine 12 is in an overload state and send an overload signal to the three-position four-way solenoid valve 14 to reduce the displacement of the hydraulic pump 1.

[0101] In one embodiment of this application, the control device further includes a second electromagnetic directional valve 17 connected to the first inlet / outlet port 2. The second electromagnetic directional valve 17 includes a third outlet position 18, the second inlet / outlet port 3 is connected to the third outlet position 18, and a damper 19 is connected between the second inlet / outlet port 3 and the third outlet position 18. The method further includes:

[0102] The second solenoid directional valve 17 receives a third control signal output by the controller 11, wherein the third control signal is used to control the second solenoid directional valve 17 to switch to the third oil outlet position 18.

[0103] To prevent hydraulic pump 1 from experiencing pressure buildup, the third oil outlet position 18 of the second solenoid directional valve 17 of the control device is connected between the first inlet / outlet port 2 and the second inlet / outlet port 3, and is connected to a damper 19. When the second solenoid directional valve 17 receives the third control signal and is energized, it can transfer the oil pressure that the travel hydraulic motor 7 cannot handle to the damper 19 for consumption, thus preventing hydraulic pump 1 from experiencing pressure buildup.

[0104] For example, according to the motion control method for skid steer in the above embodiments, the skid steer can be set to two working modes—straight-line walking mode and constant speed walking mode. When the controller 11 does not receive instructions for these two modes, the first electromagnetic reversing valve 4 and the second electromagnetic reversing valve 17 are not energized, and the synchronous hydraulic motor 10 and the damper 19 do not function.

[0105] Figure 4 This schematically illustrates a flow chart of a skid steer's straight-line travel mode according to an embodiment of this application, such as... Figure 4 As shown, when the controller 11 receives the command for the straight-line travel mode, it outputs a first control signal to the first solenoid directional valve 4 and a third control signal to the second solenoid directional valve 17. Both solenoid directional valves are energized. The first inlet / outlet port 2 and the third inlet / outlet port 8 are connected through the synchronous hydraulic motor 10, and the first inlet / outlet port 2 and the second inlet / outlet port 3 are connected through the third outlet port 18 and the damper 19. The flow rate of hydraulic oil entering or leaving the two travel hydraulic motors 7 remains consistent, enabling the skid steer to achieve straight-line travel. Hydraulic oil that cannot enter the travel hydraulic motors 7 through the synchronous hydraulic motor 10 is connected to the damper 19 to prevent the hydraulic pump 1 from pressurizing. After receiving the reset signal, the controller 11 exits the straight-line travel mode and no longer outputs the first and third control signals to the first solenoid directional valve 4 and the second solenoid directional valve 17.

[0106] Figure 5 This schematically illustrates a flow chart of a constant speed travel mode for a skid steer according to an embodiment of this application, as shown below. Figure 5 As shown, after receiving the constant speed travel mode command, the controller 11 outputs a first control signal to the first solenoid directional valve 4, a third control signal to the second solenoid directional valve 17, and a second control signal to the engine 12 and the three-position four-way solenoid valve 14. This means that, based on the skid steer's ability to travel in a straight line, the flow rate of the travel hydraulic motor 7 is kept constant, thus achieving constant speed travel for the skid steer. Upon receiving a reset signal, the controller 11 exits the constant speed travel mode and no longer outputs the first and third control signals to the first and second solenoid directional valves 4 and 17, nor does it output the second control signal to the engine 12 and the three-position four-way solenoid valve 14.

[0107] The skid steer can also have an overload protection mode. The controller 11 monitors the real-time speed of the engine 12. If the difference between the real-time speed and the engine 12 speed in the previous measurement cycle is greater than a preset threshold, it can be determined that the engine 12 is in an overload state. An overload signal is sent to the three-position four-way solenoid valve 14 to control the hydraulic pump 1 to reduce the displacement. The priority of the overload protection mode can be set above the straight-line travel mode and the constant speed travel mode. When the controller 11 outputs an overload signal, the skid steer jumps out of the straight-line travel mode or the constant speed travel mode to prevent the engine 12 from stalling or overloading.

[0108] In one embodiment of this application, a machine-readable storage medium is provided, on which instructions are stored, which, when executed by a processor, cause the processor to implement the motion control method for a skid steer described in the above embodiment.

[0109] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0110] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0111] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0112] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0113] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0114] It should also be noted that 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. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0115] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A motion control system for a skid steer machine, characterized in that, The system includes two control devices, the control devices comprising: A hydraulic pump, including a first inlet / outlet and a second inlet / outlet, is connected to an oil tank; A first electromagnetic reversing valve is connected to the first inlet and outlet ports. The first electromagnetic reversing valve includes a first outlet position and a second outlet position. The walking hydraulic motor includes a third oil inlet / outlet and a fourth oil inlet / outlet, wherein the third oil inlet / outlet is connected to the first oil outlet position, and the fourth oil inlet / outlet is connected to the second oil inlet / outlet. A synchronous hydraulic motor is connected to the second oil outlet position and to the travel hydraulic motor. The shafts of the synchronous hydraulic motors of the two control devices are fixedly connected; The system also includes a controller for outputting a first control signal to the first solenoid directional valve to control the first solenoid directional valve to switch to the second oil outlet position; An engine is connected to both the hydraulic pump and the controller, and is used to drive the hydraulic pump. The hydraulic pump is a variable displacement pump, and the control device further includes: A variable piston, the piston rod of which is connected to the movable swashplate of the hydraulic pump; A three-position four-way solenoid valve is connected to the oil tank and to the left and right cylinders of the variable piston, respectively. It is used to receive the second control signal output by the controller. The second control signal is also output to the engine to control the engine speed and control the position of the three-position four-way solenoid valve so that the flow rate of the hydraulic pump remains constant. The three-position four-way solenoid valve is connected to the oil tank via a replenishing pump.

2. The motion control system for a skid steer according to claim 1, characterized in that, The system also includes a speed sensor for acquiring the real-time engine speed. The controller is also used to acquire the real-time speed and, if the difference between the real-time speed and the engine speed in the previous measurement cycle is greater than a preset threshold, send an overload signal to the three-position four-way solenoid valve to control the three-position four-way solenoid valve to change position, thereby reducing the displacement of the hydraulic pump.

3. The motion control system for a skid steer machine according to claim 1, characterized in that, The control device further includes: The second electromagnetic reversing valve is connected to the first inlet and outlet ports. The second electromagnetic reversing valve includes a third outlet position. The second electromagnetic reversing valve is used to receive a third control signal output by the controller. The third control signal is used to control the second electromagnetic reversing valve to switch to the third outlet position. The second oil inlet / outlet is connected to the third oil outlet. The damper is connected between the second oil inlet / outlet and the third oil outlet.

4. The motion control system for a skid steer machine according to claim 1, characterized in that, The control device further includes: The flushing valve is connected in parallel with the walking hydraulic motor and is connected to the oil tank through an overflow valve.

5. The motion control system for a skid steer according to claim 1, characterized in that, The control device further includes: The first pressure-stabilizing overflow valve has its inlet connected to the first inlet / outlet, and its outlet connected to the oil tank. The second pressure-stabilizing overflow valve has its inlet connected to the second inlet / outlet, and its outlet connected to the oil tank. The first check valve, connected in parallel with the first pressure-stabilizing relief valve, is connected to the walking hydraulic motor; The second check valve, connected in parallel with the second pressure-stabilizing relief valve, is connected to the walking hydraulic motor; Both the first check valve and the second check valve are connected to the replenishing pump, which is connected to the oil tank.

6. A skid steer, comprising a motion control system for a skid steer as described in any one of claims 1-5.

7. A motion control method for a skid steer machine, characterized in that, The method, applied to the motion control system for a skid steer as described in any one of claims 1-5, comprises: The controller outputs a first control signal to the first solenoid directional valve to control the first solenoid directional valve to switch to the second oil outlet position.

8. The method according to claim 7, characterized in that, The control device further includes a variable piston, the piston rod of which is connected to the movable swashplate of the hydraulic pump; a three-position four-way solenoid valve, connected to the oil tank and respectively connected to the left and right cylinders of the variable piston; the three-position four-way solenoid valve is connected to the oil tank via a replenishing pump; the method further includes: The second control signal output by the controller is received through the three-position four-way solenoid valve. The second control signal is also output to the engine to control the engine speed and control the position of the three-position four-way solenoid valve so that the flow rate of the hydraulic pump remains constant.

9. The motion control method for a skid steer machine according to claim 8, characterized in that, The system also includes a speed sensor for acquiring real-time engine speed, and the method further includes: The controller obtains the real-time rotational speed. If the difference between the real-time rotational speed and the engine speed of the previous measurement cycle is greater than a preset threshold, an overload signal is sent to the three-position four-way solenoid valve to control the three-position four-way solenoid valve to change position, thereby reducing the displacement of the hydraulic pump.

10. The method according to claim 7, characterized in that, The control device further includes a second electromagnetic directional valve connected to the first inlet / outlet port. The second electromagnetic directional valve includes a third outlet position, the second inlet / outlet port being connected to the third outlet position, and a damping element connected between the second inlet / outlet port and the third outlet position. The method further includes: The second electromagnetic reversing valve receives a third control signal output by the controller, wherein the third control signal is used to control the second electromagnetic reversing valve to switch to the third oil outlet position.

11. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions that, when executed by a processor, cause the processor to implement the motion control method for a skid steer according to any one of claims 7-10.

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