A hydrostatic drive control system, control method and loader

Abstract

This invention discloses a hydrostatic drive control system, control method, and loader. The system includes a walking system and a working system; the walking system includes a vehicle controller, an engine controller, an engine, an electronically controlled closed-loop variable pump, and an electronically controlled variable motor; the working system includes a fixed-displacement hydraulic pump, control valves, working hydraulic cylinders, and a hydraulic motor; the input terminal of the vehicle controller is connected to the output terminal of the engine controller and the signal output terminals of the loader's throttle pedal, hand throttle knob, speed limiter knob, and FNR selector switch. Based on the coupling and decoupling control of engine speed and electronically controlled closed-loop variable pump displacement under different operating conditions, two different working modes are formed. This allows for both vehicle speed and engine speed following control and vehicle speed and engine speed separation control, solving the problems of poor coordination between vehicle speed and attachment operation speed and complex operation under conditions of close-range loading and constant attachment flow. Multi-level proportional control of the electronically controlled closed-loop variable pump displacement enables the limitation of any real-time vehicle speed, solving the problem of convenient control of vehicle speed requirements under different operating conditions.

Description

Technical Field

[0001] This invention relates to a hydrostatic drive control system, control method, and loader, belonging to the technical fields of engineering machinery and forestry machinery. Background Technology

[0002] The hydrostatic loader's travel system consists of a closed-loop system composed of a closed-circuit variable hydraulic pump and a variable hydraulic motor, replacing the hydraulic torque converter and gearbox in the traditional drive system. It not only meets the basic driving functions of the vehicle, but also, compared with the traditional drive system, can achieve continuous stepless speed regulation across the entire speed range, high traction force at low engine speeds and precise traction force adjustment, power shifting during driving, quick and convenient reversing, and the integration of inch-by-inch auxiliary braking and mechanical braking. These advantages make the hydrostatic drive system have a wider application prospect in the small and medium tonnage loader market.

[0003] Hydrostatic loaders complete operations through the coordinated use of their travel system and working device. Both the travel drive hydrostatic system and the working hydraulic system's power components, the hydraulic pumps, are driven by the engine. The vehicle speed follows the engine speed, and the working device's operating speed also follows the engine speed. For short-distance loading operations, the travel speed doesn't need to be too high, but the working device needs to complete the loading operation quickly. To increase the working device's operating speed, the engine speed is increased, which in turn increases the travel speed. To limit the speed to a lower level, the accelerator pedal needs to be pressed to reduce the speed. For working conditions with constant attachment flow (sweeping, snow removal), the engine speed must remain constant to maintain the attachment flow, therefore the vehicle speed cannot be arbitrarily changed. This means that both the travel speed and attachment operation can only be controlled by simultaneously pressing the accelerator and brake pedals, resulting in poor speed coordination and increased operational difficulty.

[0004] For the decoupled control of the travel speed and the working attachment movement speed of a hydrostatic loader, the existing technical solution uses an electronically controlled closed-loop variable hydraulic pump in the travel system and an electronically controlled variable hydraulic pump in the working system. The required displacement of the electronically controlled closed-loop variable pump in the travel system is controlled by the throttle electrical signal, so that the travel speed is independently controlled. The required displacement of the electronically controlled variable hydraulic pump in the working system is controlled by the handle electrical signal, so that the movement speed of the working system is independently controlled.

[0005] However, the above technical solution has the following drawbacks: (1) The method of independently controlling the speed of the walking system and the working system and the speed of the attachments is only applicable to devices in which both the walking system and the working system are equipped with electronically controlled variable pumps. The cost is relatively high. However, it cannot meet the requirements for devices in which the walking system is equipped with an electronically controlled variable pump and the working system is a fixed pump, thus limiting its application scope. (2) The method of independently controlling the vehicle speed and attachment operation speed of the walking system and the working system is essentially to control the displacement of the two systems' electro-hydraulic pumps separately, which cannot achieve separate control of vehicle speed and engine speed; Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a hydrostatic drive control system, control method, and loader. Based on the coupling and separation control of engine speed and electronically controlled closed variable pump displacement under different operating conditions, two different working modes are formed. It can realize vehicle speed and engine speed following control, or vehicle speed and engine speed separation control, solving the problems of poor coordination between vehicle speed and attachment operation speed and complex operation when the loader is loading at close distances and the attachment flow is constant. Multi-level proportional control of electronically controlled closed variable pump displacement enables the limitation of arbitrary real-time vehicle speed, solving the problem of convenient control of vehicle speed requirements under different operating conditions.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A hydrostatic drive control system includes a walking system and a working system; The walking system includes a vehicle controller, an engine controller, an engine, an electronically controlled closed-loop variable pump, and an electronically controlled variable motor. The working system includes a fixed-displacement hydraulic pump, a control valve, a working hydraulic cylinder, and a hydraulic motor; wherein, The output terminal of the vehicle controller is connected to the input terminals of the engine controller, the electronically controlled closed variable pump, the electronically controlled variable motor, and the control valve, respectively. The input terminal of the vehicle controller is connected to the output terminal of the engine controller and the signal output terminals of the loader's accelerator pedal, speed limiter knob, and FNR selector switch. The input end of the engine is connected to the output end of the engine controller, and the output shaft end of the engine is connected to the input shaft ends of the electronically controlled closed variable pump and the fixed displacement hydraulic pump, respectively. The two oil ports of the electronically controlled closed variable pump and the two oil ports of the electronically controlled variable motor are respectively connected by pipelines to form a closed loop, and the output shaft end of the electronically controlled variable motor is connected to the wheel of the reduction device. The output port of the quantitative hydraulic pump is connected to the inlet of the control valve via a pipeline, and the outlet of the control valve is connected to the inlet of the working hydraulic cylinder and / or the hydraulic motor.

[0008] The aforementioned hydrostatic drive control system is characterized in that: the input terminal of the vehicle controller is also connected to the signal output terminal of the loader's working mode selection switch, and the working mode selection switch provides at least two different working mode selection signals.

[0009] The aforementioned hydrostatic drive control system is characterized in that: the input terminal of the vehicle controller is also connected to the signal output terminal of the loader's hand throttle knob.

[0010] The aforementioned hydrostatic drive control system is characterized in that: the output flow rate of the fixed-displacement hydraulic pump is controlled by the engine speed, and the flow rate of the fixed-displacement hydraulic pump into the working hydraulic cylinder and / or hydraulic motor is determined by the opening degree of the control valve. Electro-controlled closed-loop variable pump. The aforementioned hydrostatic drive control system is characterized in that: the operating speed of the working hydraulic cylinder and the hydraulic motor is jointly controlled by the engine speed and the control valve opening; when the control valve opening is constant, the operating speed of the working hydraulic cylinder or the hydraulic motor is controlled only by the engine speed. The control method using the aforementioned hydrostatic drive control system includes the following steps: (1) Input the corresponding selection signal to the vehicle controller through the loader's mode selection switch and FNR selection switch; (2) Transmit the output signals of the loader's throttle pedal and / or hand throttle knob to the vehicle controller. If only one of the signals is transmitted to the vehicle controller, the vehicle controller converts that signal into an engine request speed value and transmits it to the engine controller. If two corresponding signals are transmitted to the vehicle controller, the vehicle controller will convert the two signals into two corresponding engine request speed values ​​and take the larger value to transmit to the engine controller. (3) The engine controller feeds back the actual speed value of the engine to the vehicle controller, and the vehicle controller generates the first displacement value of the electronically controlled closed variable pump based on the actual speed value; at the same time, the engine drives the fixed displacement hydraulic pump to work under the actual speed value, and the output flow of the fixed displacement hydraulic pump drives the working hydraulic cylinder and / or hydraulic motor to move through the control valve. (4) Input the speed limit signal to the vehicle controller through the speed limiter knob, and the vehicle controller calculates the second displacement value of the electronically controlled closed variable pump corresponding to the speed limit signal; (5) Compare the first displacement value and the second displacement value in steps (3) and (4), and take the smaller value as the actual displacement value of the current electronically controlled closed variable pump under the control of the speed limiter knob. The output flow of the electronically controlled closed variable pump under the actual displacement value enters the electronically controlled variable motor, drives the electronically controlled variable motor to rotate, and then drives the vehicle to move through the deceleration device.

[0011] The aforementioned control method for a hydrostatic drive control system is characterized in that: in step (3), when the opening of the control valve is fixed, the operating speed of the working hydraulic cylinder and / or hydraulic motor follows the engine speed controlled by the accelerator pedal and the hand throttle knob.

[0012] The control method using the aforementioned hydrostatic drive control system includes the following steps: (1) Input the corresponding selection signal to the vehicle controller through the loader's mode selection switch and FNR selection switch; (2) The output signal of the loader's hand throttle knob is transmitted to the vehicle controller, converted into the engine request speed value, and transmitted to the engine controller. The engine controller feeds back the actual speed of the engine to the vehicle controller in real time. At the same time, the engine drives the fixed displacement hydraulic pump to work. The output flow of the fixed displacement hydraulic pump drives the working hydraulic cylinder and / or hydraulic motor to move through the control valve. (3) The output signal of the loader's accelerator pedal is transmitted to the vehicle controller, and the vehicle controller generates the first displacement value of the electronically controlled closed variable pump from the signal; at the same time, the output signal of the loader's speed limiter knob is transmitted to the vehicle controller, and the vehicle controller generates the third displacement value of the electronically controlled closed variable pump from the signal. (4) Compare the first displacement value and the third displacement value in step (3), and take the larger value as the actual displacement value of the current electronically controlled closed variable pump under the joint control of the accelerator pedal and the speed limiter knob. The output flow of the electronically controlled closed variable pump under this actual displacement value enters the electronically controlled variable motor, drives the electronically controlled variable motor to rotate, and then drives the vehicle to move through the deceleration device.

[0013] The aforementioned control method for a hydrostatic drive control system is characterized in that: in step (2), when the opening of the control valve is fixed, the operating speed of the working hydraulic cylinder and / or hydraulic motor follows the engine speed controlled by the hand throttle knob.

[0014] A loader equipped with the aforementioned hydrostatic drive control system.

[0015] The beneficial effects of this invention are: (1) The engine speed and the electronically controlled closed variable pump displacement are coupled and separated, which can realize both vehicle speed and engine speed following control and vehicle speed and engine speed separation control. Furthermore, by adding a hand throttle knob, a speed limiter knob and a working mode selection switch, two working modes are formed. (2) The walking system adopts an electro-hydraulic control system and the working system adopts a hydraulic control system, which can realize independent control of the walking system and the working system, and meet the precise coordinated control of vehicle speed and attachment movement speed under close-range loading operations and attachment flow constant working conditions; (3) Multi-stage proportional control of the displacement of the electronically controlled closed variable pump is implemented to limit the vehicle speed in any real time, thus solving the problem of convenient control of vehicle speed requirements under different working conditions. Attached Figure Description

[0016] Figure 1This is a schematic diagram of a hydrostatic drive control system according to the present invention; Figure 2 This is a schematic diagram of the working mode of the second embodiment of the present invention; Figure 3 This is a schematic diagram of the working mode of the third embodiment of the present invention; The components include: 1. Engine; 2. Engine controller; 3. Electronically controlled closed-loop variable pump; 4. Electronically controlled variable motor; 6. Reducer wheel; 8. Vehicle controller; 9. Accelerator pedal; 10. Hand throttle knob; 11. Speed ​​limiter knob; 12. Operating mode selection switch; 13. FNR selection switch; 14. Fixed displacement hydraulic pump; 15. Control valve; 16. Working hydraulic cylinder; 17. Hydraulic motor. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0018] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. Example 1

[0019] Figure 1 This is a schematic diagram of a hydrostatic drive control system provided in Embodiment 1 of the present invention. The control system mainly includes a walking system and a working system; the walking system includes a vehicle controller 8, an engine controller 2, an engine 1, an electronically controlled closed-loop variable pump 3, and an electronically controlled variable motor 4; the working system includes a fixed displacement hydraulic pump 14, a control valve 15, a working hydraulic cylinder 16, and a hydraulic motor 17.

[0020] Specifically, the output terminal of the vehicle controller 8 is connected to the input terminals of the engine controller 2, the electronically controlled closed variable pump 3, the electronically controlled variable motor 4, and the control valve 15, respectively. The input terminal of the vehicle controller 8 is connected to the output terminal of the engine controller 2 and the signal output terminals of the loader's accelerator pedal 9, speed limiter knob 11, and FNR selector switch 13. The input end of the engine 1 is connected to the output end of the engine controller 2, and the output shaft end of the engine is connected to the input shaft ends of the electronically controlled closed variable pump 3 and the fixed displacement hydraulic pump 14, respectively. The two oil ports of the electronically controlled closed variable pump 3 and the two oil ports of the electronically controlled variable motor 4 are connected by pipelines to form a closed loop, and the output shaft end of the electronically controlled variable motor 4 is connected to the wheel 6 of the reduction device. In this embodiment, the input end of the vehicle controller is also connected to the signal output end of the loader's hand throttle knob 10.

[0021] In actual operation, the walking system inputs an engine speed request signal to the vehicle controller 8 via the accelerator pedal 9 and / or the hand throttle knob 10. This request signal is then converted into an engine speed request and transmitted to the engine controller 2. The engine controller 2 and the vehicle controller 8 are connected via CAN communication to control the engine speed request and provide feedback on the actual engine speed. Combined with the speed limiter signal transmitted to the vehicle controller 8 via the speed limiter knob 11, the vehicle controller 8 outputs a current signal through its algorithm to control the displacement of the electronically controlled closed variable pump 3 and the electronically controlled variable motor 4. This drives the wheels 6 of the reduction gear to move at the corresponding speed, thus achieving separate control of vehicle speed and engine speed.

[0022] In the working system, the output port of the fixed-displacement hydraulic pump 14 is connected to the inlet of the control valve 15 via a pipeline, and the outlet of the control valve 15 is connected to the inlet of the working hydraulic cylinder 16 and / or the hydraulic motor 17. Since the displacement of the fixed-displacement hydraulic pump 14 is fixed, its output flow rate is controlled by the engine speed. The amount of flow from the fixed-displacement hydraulic pump 14 into the working hydraulic cylinder 16 and the hydraulic motor 17 via the control valve 15 is determined by the opening degree of the control valve. The operating speed of the working hydraulic cylinder 16 and the hydraulic motor 17 is jointly controlled by the engine speed and the opening degree of the control valve. With a fixed control valve opening, the operating speed of the hydraulic cylinder or the hydraulic motor is controlled solely by the engine speed.

[0023] This solves the problems of poor coordination between vehicle speed and attachment operation speed and complex operation when the loader is loading at close range and the attachment flow rate is constant. By controlling the displacement of the electronically controlled closed variable pump in multiple stages, it is possible to limit the vehicle speed at any real time and solve the problem of convenient control of vehicle speed requirements under different working conditions.

[0024] Electrically controlled closed-loop variable pump The input terminal of the vehicle controller is also connected to the signal output terminal of the loader's operating mode selection switch. The operating mode selection switch can provide at least two different operating mode selection signals. In this embodiment, the hydrostatic drive control system can select, as needed, two different operating modes—coupled control and decoupled control of engine speed and electronically controlled closed-loop variable pump displacement—via the operating mode selection switch. Example 2

[0025] like Figure 1 and Figure 2 As shown, a control method for a hydrostatic drive control system includes the following steps when the vehicle controller 8 receives a signal from the operating mode selection switch 12 to select operating mode 1 (i.e., selecting engine speed coupled with electronically controlled closed-loop variable pump displacement control): (1) The corresponding selection signal is input to the vehicle controller 8 through the FNR selection switch 13 of the loader. In this embodiment, the selection F signal is used as an example for explanation; (2) The output signals of the accelerator pedal 9 and / or the hand throttle knob 10 of the loader are transmitted to the vehicle controller 8. If only one of the signals is transmitted to the vehicle controller 8, the vehicle controller 8 converts the signal into an engine request speed value and transmits it to the engine controller 2. If two corresponding signals are transmitted to the vehicle controller 8, the vehicle controller 8 converts the two signals into two corresponding engine request speed values ​​and takes the larger value and transmits it to the engine controller 2. (3) The engine controller 2 feeds back the actual speed value of the engine 1 to the vehicle controller 8, and the vehicle controller 8 generates the first displacement value of the electronically controlled closed variable pump 3 based on the actual speed value; at the same time, the engine 1 drives the fixed displacement hydraulic pump 14 to work under the actual speed value. The output flow of the fixed displacement hydraulic pump 14 drives the working hydraulic cylinder 16 and / or the hydraulic motor 17 to act through the control valve 15. Since the displacement of the fixed displacement hydraulic pump 14 is a fixed value, when the opening of the control valve 15 is constant, the flow rate input to the working hydraulic cylinder 16 and the hydraulic motor 17 is only determined by the engine speed controlled by the accelerator pedal and the hand throttle knob. That is, the hydraulic cylinder action speed of the working system changes with the engine speed. (4) Input the speed limit signal to the vehicle controller 8 through the speed limiter knob 11, and the vehicle controller 8 calculates the second displacement value of the electronically controlled closed variable pump corresponding to the speed limit signal; (5) Compare the first displacement value and the second displacement value in steps (3) and (4), and take the smaller value as the actual displacement value of the current electronically controlled closed variable pump 3 under the control of speed limiter knob 11. The output flow of the electronically controlled closed variable pump 3 under the actual displacement value enters the electronically controlled variable motor 4, drives the electronically controlled variable motor 4 to rotate, and then drives the vehicle to move through the deceleration device.

[0026] In this embodiment, the speed limiter knob 11 is an operating device that, when moved to a certain position, will not automatically return to its initial position upon release. Its operating signal is input to the vehicle controller 8, and through a multi-level proportional control method, a second displacement of the electronically controlled closed variable pump 3 corresponding to the current engine speed is generated. The initial position of the speed limiter knob 11 corresponds to the first displacement of the electronically controlled closed variable pump 3 at any current engine speed, and the final position of the speed limiter knob 11 corresponds to a zero displacement of the electronically controlled closed variable pump 3. Each position in the middle of the speed limiter knob 11 corresponds to a second displacement of the electronically controlled closed variable pump. By comparing the first displacement and the second displacement and taking the smaller value (when the speed limiter knob 11 inputs a speed limit signal, if the second displacement generated corresponding to the input speed limit value is greater than the current first displacement, it indicates that the speed limited by the speed limiter knob 11 is greater than the speed generated by the accelerator pedal 9 and / or the hand throttle knob 10), the speed limiter is determined. The speed limiter knob 11 controls the loader to move at the speed generated by the operator's actual operation of the accelerator pedal 9 and / or hand throttle knob 10 by selecting a smaller displacement value. That is, the speed limit signal input by the speed limiter knob 11 does not actually limit the vehicle speed. If the second displacement generated corresponding to the input speed limit value is less than the current first displacement, it indicates that the speed limited by the speed limiter knob 11 is less than the speed generated by the accelerator pedal 9 and / or hand throttle knob 10. The loader is controlled to move at the speed limited by the speed limiter knob 11 by selecting a smaller value. The speed limiter knob 11 controls the displacement of the electronically controlled closed variable pump generated at the current engine speed through multi-level proportional control. Under the real-time limitation of the current vehicle speed, the engine speed is increased by operating the accelerator pedal 9 or hand throttle knob 10. Under the limitation of the vehicle speed by the speed limiter knob 11, the flow rate of the fixed displacement hydraulic pump 14 of the working system is increased, thereby accelerating the action speed of the working hydraulic cylinder 16. It solves the problems of poor coordination between vehicle speed and working device speed in close-range loading conditions, as well as the difficulty for operators to simultaneously accelerate the working device while applying the brakes. Example 3

[0027] like Figure 1 and Figure 3 As shown, a control method for a hydrostatic drive control system includes the following steps when the vehicle controller 8 receives a signal from the operating mode selection switch 12 to select operating mode 2 (i.e., to select separate control of engine speed and electronically controlled closed-loop variable pump displacement): (1) The corresponding selection signal is input to the vehicle controller through the FNR selection switch 13 of the loader. In this embodiment, the selection F signal is used as an example for explanation; (2) The output signal of the loader's hand throttle knob 10 is transmitted to the vehicle controller 8, converted into the engine request speed value, and transmitted to the engine controller 2. The engine controller 2 feeds back the actual speed of the engine 1 to the vehicle controller 8 in real time. At the same time, the engine drives the fixed displacement hydraulic pump 14 to work. The output flow of the fixed displacement hydraulic pump 14 drives the working hydraulic cylinder 16 and / or the hydraulic motor 17 to move through the control valve 15. Under the fixed opening of the control valve 15, the rotation speed of the working hydraulic cylinder 16 and the hydraulic motor 17 is determined only by the engine speed controlled by the hand throttle knob. (3) The output signal of the accelerator pedal 9 of the loader is transmitted to the vehicle controller 8, and the vehicle controller 8 generates the first displacement value of the electronically controlled closed variable pump from the signal; at the same time, the output signal of the speed limiter knob 11 of the loader is transmitted to the vehicle controller 8, and the vehicle controller 8 generates the third displacement value of the electronically controlled closed variable pump from the signal. (4) Compare the first displacement value and the third displacement value in step (3), and take the larger value as the actual displacement value of the current electronically controlled closed variable pump under the joint control of the accelerator pedal and the speed limiter knob. The output flow of the electronically controlled closed variable pump under this actual displacement value enters the electronically controlled variable motor, drives the electronically controlled variable motor to rotate, and then drives the vehicle to move through the deceleration device.

[0028] Thus, the engine speed is controlled by the hand throttle knob 10, and the displacement of the electronically controlled closed variable pump 3 is controlled by the throttle pedal 9 and / or the speed limiter knob 11, thereby achieving separate control of the engine speed and the displacement of the electronically controlled closed variable pump 3, that is, the vehicle speed and the engine speed are separated, thus realizing independent control of the travel system and the working system.

[0029] When the attachment speed of the working system needs to be kept constant, the engine speed is locked by turning the hand throttle knob 10 to a certain position, so that the flow rate of the fixed-displacement hydraulic pump 14 of the working system remains constant. With the opening of the control valve 15 fixed, the flow rate of the hydraulic cylinder 16 and the hydraulic motor 17 is constant, thus achieving a constant attachment speed. When it is necessary to change from a smaller constant attachment speed to a larger constant attachment speed, the hand throttle knob 10 is turned to increase and lock a larger engine speed, thereby increasing and maintaining a larger attachment speed.

[0030] At the same time, the displacement of the electronically controlled closed variable pump 3 is locked by the speed limiter knob 11 to keep the vehicle speed constant. The displacement of the electronically controlled closed variable pump 3 can also be increased by pressing the accelerator pedal 9 to increase the vehicle speed (the larger value of the displacement generated by the speed limiter knob 11 signal and the accelerator pedal 9 signal is taken as the actual displacement value of the electronically controlled closed variable pump under the joint control of the accelerator pedal and the speed limiter knob). When the accelerator pedal is released, the vehicle speed returns to the original speed. This can be used in working conditions that require the attachment to have a constant operating speed, such as cleaning conditions.

[0031] Based on Embodiments 2 and 3, it can be seen that the throttle knob 10 and the speed limiter knob 11 are operating devices that do not automatically return to their initial positions after being moved to a certain position and released. In operating mode 1, the throttle knob 10 can not only control the engine speed, but also indirectly control the displacement of the electronically controlled closed variable pump 3. The speed limiter knob 11 provides multi-level proportional control of the current electronically controlled closed variable pump displacement. In operating mode 2, the throttle knob 10 only controls the engine speed, while the speed limiter knob 11 generates the displacement control of the electronically controlled closed variable pump 3. The functions of the throttle knob 10 and the speed limiter knob 11 are different in different operating modes. Example 4

[0032] Based on the hydrostatic drive control system described in Embodiment 1, this embodiment provides a loader, which is equipped with the hydrostatic drive control system described in Embodiment 1.

[0033] It should be noted that this invention is based on adding a hand throttle knob, a speed limiter knob, and a working mode selection switch, combined with the accelerator pedal controlling engine speed and the electronically controlled closed variable pump displacement, forming two working modes: coupled and decoupled control of engine speed and electronically controlled closed variable pump displacement. The hand throttle knob and speed limiter knob can be replaced with any analog switch. This invention allows the hand throttle knob to control and lock the engine speed, or a single switch button to lock the real-time engine speed. Each press of the two switches increases or decreases the fixed engine speed, achieving engine speed control. This invention allows for linear coupling between engine speed and electronically controlled closed variable pump displacement, or non-linear coupling. Any coupling or decoupling control of engine speed and electronically controlled closed variable pump displacement achieved through equivalent substitution or transformation falls within the protection scope of this invention.

[0034] In summary, the hydrostatic drive control system, control method, and loader of the present invention form two different working modes based on the coupling and separation control of engine speed and electronically controlled closed variable pump displacement under different operating conditions. This allows for both vehicle speed and engine speed following control and vehicle speed and engine speed separation control.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A hydrostatic drive control system, characterized in that: Includes walking systems and working systems; The walking system includes a vehicle controller, an engine controller, an engine, an electronically controlled closed-loop variable pump, and an electronically controlled variable motor. The working system includes a fixed-displacement hydraulic pump, a control valve, a working hydraulic cylinder, and a hydraulic motor; wherein, The output terminal of the vehicle controller is connected to the input terminals of the engine controller, the electronically controlled closed variable pump, the electronically controlled variable motor, and the control valve, respectively. The input terminal of the vehicle controller is connected to the output terminal of the engine controller and the signal output terminals of the loader's accelerator pedal, speed limiter knob, and FNR selector switch. The input end of the engine is connected to the output end of the engine controller, and the output shaft end of the engine is connected to the input shaft ends of the electronically controlled closed variable pump and the fixed displacement hydraulic pump, respectively. The two oil ports of the electronically controlled closed variable pump and the two oil ports of the electronically controlled variable motor are respectively connected by pipelines to form a closed loop, and the output shaft end of the electronically controlled variable motor is connected to the wheel of the reduction device. The output port of the quantitative hydraulic pump is connected to the inlet of the control valve via a pipeline, and the outlet of the control valve is connected to the inlet of the working hydraulic cylinder and / or the hydraulic motor. The input terminal of the vehicle controller is also connected to the signal output terminal of the loader's working mode selection switch, and the working mode selection switch provides at least two different working mode selection signals. The input terminal of the vehicle controller is also connected to the signal output terminal of the loader's hand throttle knob; This hydrostatic drive control system can select between two different operating modes—coupled control and decoupled control—of engine speed and electronically controlled closed variable pump displacement, via a working mode selection switch, as needed.

2. The hydrostatic drive control system according to claim 1, characterized in that: The output flow rate of the fixed-displacement hydraulic pump is controlled by the engine speed, and the flow rate of the fixed-displacement hydraulic pump into the working hydraulic cylinder and / or hydraulic motor is determined by the opening degree of the control valve.

3. The hydrostatic drive control system according to claim 2, characterized in that: The operating speed of the working hydraulic cylinder and the hydraulic motor is jointly controlled by the engine speed and the opening of the control valve. When the opening of the control valve is constant, the operating speed of the working hydraulic cylinder or the hydraulic motor is controlled only by the engine speed.

4. A hydrostatic drive control system according to any one of claims 1-3, characterized in that: When the vehicle controller receives a working mode selection switch indicating that the engine speed and electronically controlled closed-loop variable pump displacement are coupled for control, the following steps are included: (1) Input the corresponding selection signal to the vehicle controller through the loader's mode selection switch and FNR selection switch; (2) Transmit the output signals of the loader's throttle pedal and / or hand throttle knob to the vehicle controller. If only one of the signals is transmitted to the vehicle controller, the vehicle controller converts that signal into an engine request speed value and transmits it to the engine controller. If two corresponding signals are transmitted to the vehicle controller, the vehicle controller will convert the two signals into two corresponding engine request speed values ​​and take the larger value to transmit to the engine controller. (3) The engine controller feeds back the actual speed value of the engine to the vehicle controller, and the vehicle controller generates the first displacement value of the electronically controlled closed variable pump based on the actual speed value; at the same time, the engine drives the fixed displacement hydraulic pump to work under the actual speed value, and the output flow of the fixed displacement hydraulic pump drives the working hydraulic cylinder and / or hydraulic motor to move through the control valve. (4) Input the speed limit signal to the vehicle controller through the speed limiter knob, and the vehicle controller calculates the second displacement value of the electronically controlled closed variable pump corresponding to the speed limit signal; (5) Compare the first displacement value and the second displacement value in steps (3) and (4), and take the smaller value as the actual displacement value of the current electronically controlled closed variable pump under the control of the speed limiter knob. The output flow of the electronically controlled closed variable pump under the actual displacement value enters the electronically controlled variable motor, drives the electronically controlled variable motor to rotate, and then drives the vehicle to move through the deceleration device.

5. A hydrostatic drive control system according to claim 4, characterized in that: In step (3), with the control valve opening fixed, the operating speed of the working hydraulic cylinder and / or hydraulic motor follows the engine speed controlled by the accelerator pedal and the hand throttle knob.

6. A hydrostatic drive control system according to any one of claims 1-3, characterized in that: When the vehicle controller receives a working mode selection switch indicating that engine speed and electronically controlled closed-loop variable pump displacement are to be controlled separately, the following steps are included: (1) Input the corresponding selection signal to the vehicle controller through the loader's mode selection switch and FNR selection switch; (2) The output signal of the loader's hand throttle knob is transmitted to the vehicle controller, converted into the engine request speed value, and transmitted to the engine controller. The engine controller feeds back the actual speed of the engine to the vehicle controller in real time. At the same time, the engine drives the fixed displacement hydraulic pump to work. The output flow of the fixed displacement hydraulic pump drives the working hydraulic cylinder and / or hydraulic motor to move through the control valve. (3) The output signal of the loader's accelerator pedal is transmitted to the vehicle controller, and the vehicle controller generates the first displacement value of the electronically controlled closed variable pump from the signal; at the same time, the output signal of the loader's speed limiter knob is transmitted to the vehicle controller, and the vehicle controller generates the third displacement value of the electronically controlled closed variable pump from the signal. (4) Compare the first displacement value and the third displacement value in step (3), and take the larger value as the actual displacement value of the current electronically controlled closed variable pump under the joint control of the accelerator pedal and the speed limiter knob. The output flow of the electronically controlled closed variable pump under this actual displacement value enters the electronically controlled variable motor, drives the electronically controlled variable motor to rotate, and then drives the vehicle to move through the deceleration device.

7. A hydrostatic drive control system according to claim 6, characterized in that: In step (2), with the control valve opening fixed, the operating speed of the working hydraulic cylinder and / or hydraulic motor follows the engine speed controlled by the hand throttle knob.

8. A loader, characterized in that: The loader is equipped with a hydrostatic drive control system as described in any one of claims 1-3.

Images