Hydrostatic drive control system, control method and loader

Abstract

The invention discloses a hydrostatic drive control system, a hydrostatic drive control method and a loader. The system comprises a walking system and a working system, the walking system comprises a whole vehicle controller, an engine controller, an engine, an electric control closed variable pump and an electric control variable motor. The working system comprises a quantitative hydraulic pump, a control valve, a working hydraulic cylinder and a hydraulic motor; the input end of the whole vehicle controller is connected with the output end of the engine controller and the signal output ends of an accelerator pedal, a hand accelerator knob, a speed governor knob and an FNR selection switch of the loader. Two different working modes are formed based on coupling and separation control of the engine rotating speed and the electric control closed variable pump displacement under different use working conditions, so that following control over the vehicle speed and the engine rotating speed can be achieved, and separation control over the vehicle speed and the engine rotating speed can also be achieved. The problems that under the working conditions of close-range loading of the loader and constant accessory flow, the vehicle speed and accessory operation action speed are poor in collaboration, and control is complex are solved. And the displacement of the electric control closed variable pump is subjected to multi-stage proportional control, so that any real-time vehicle speed is limited, and the vehicle speed requirements under different working conditions are conveniently controlled.

Description

Technical Field

[0001] The present invention relates to a hydrostatic drive control system, a control method and a loader, belonging to the technical fields of construction machinery and forestry machinery. Background Art

[0002] The traveling system of a hydrostatic loader consists of a closed-loop variable hydraulic pump and a variable hydraulic motor to form a closed loop, replacing the torque converter and gearbox in the traditional drive system. It not only meets the basic functions of vehicle driving, but also, compared with the traditional drive system, can achieve continuously variable speed regulation in the full speed range, large traction force at low engine speeds and precise traction force adjustment, power shift during driving, quick and convenient commutation, integration of inch forward auxiliary braking and mechanical braking. These advantages make the hydrostatic drive system have a wider application prospect in the market of medium and small tonnage loaders.

[0003] The hydrostatic loader completes operations through the cooperation of the traveling system and the working device. The power element hydraulic pumps of the traveling drive hydrostatic system and the working hydraulic system are both driven by the engine. The driving speed follows the engine speed, and the operating speed of the working device also follows the engine speed. For short-distance loading operations, the driving speed does not need to be too high, and the working device needs to complete the loading operation quickly. In order to increase the operating speed of the working device, the engine speed is increased, and the driving speed increases accordingly. In order to limit the speed to a smaller value, the inch forward pedal needs to be stepped on to reduce the speed. For the constant flow rate condition of attachments (sweeping, snow removal), in order to keep the flow rate of the attachments constant, the engine speed must remain unchanged. Therefore, the vehicle speed cannot be changed arbitrarily. In this way, there is a problem that the driving speed and the operating speed of the attachments can only be controlled by stepping on the accelerator pedal and the brake pedal at the same time, resulting in poor speed coordination between the two and increased control difficulty.

[0004] For the decoupled control of the driving speed of the hydrostatic loader and the operating speed of the working attachments, the existing technical solutions use an electronically controlled closed-loop variable hydraulic pump for the traveling system and an electronically controlled variable hydraulic pump for the working system. The required displacement of the electronically controlled closed-loop variable of the traveling system is controlled by the throttle electrical signal to independently control the vehicle speed of the traveling system, and the required displacement of the electronically controlled variable hydraulic pump of the working system is controlled by the handle electrical signal to independently control the operating speed of the working system.

[0005] However, the above technical solutions have the following disadvantages: (1) The method of independently controlling the vehicle speed of the traveling system and the working system and the operating speed of the attachments is only applicable to devices equipped with electronically controlled variable pumps for both the traveling system and the working system, and the cost is relatively high. For devices with an electronically controlled variable pump configured for the traveling system and a fixed-displacement pump for the working system, the requirements cannot be met, and the application range is limited; (2) The essence of the method of independently controlling the vehicle speed of the walking system and the working system and the operation speed of the attachment is to separately control the displacement of the electro-hydraulic pumps of the two systems, and it is impossible to achieve separate control of the vehicle speed and the engine speed; Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a hydrostatic drive control system, a control method and a loader. Based on the coupling and separation control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump under different operating conditions, two different working modes are formed. It can not only achieve the follow-up control of the vehicle speed and the engine speed, but also achieve the separate control of the vehicle speed and the engine speed, and solve the problems of poor coordination and complex operation between the vehicle speed and the operation speed of the attachment under the conditions of short-distance loading of the loader and constant flow of the attachment; multi-stage proportional control of the displacement of the electro-hydraulic closed-loop variable pump is carried out to achieve the limitation of any real-time vehicle speed, and solve the convenient control of the vehicle speed requirements under different working conditions.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are 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 electro-hydraulic closed-loop variable pump and an electro-hydraulic 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 end of the vehicle controller is respectively connected to the input ends of the engine controller, the electro-hydraulic closed-loop variable pump, the electro-hydraulic variable motor and the control valve, and the input end of the vehicle controller is connected to the output end of the engine controller and the signal output ends of the accelerator pedal, the speed limiter knob and the FNR selection switch of the loader; 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 respectively connected to the input shaft ends of the electro-hydraulic closed-loop variable pump and the fixed-displacement hydraulic pump; The two oil ports of the electro-hydraulic closed-loop variable pump and the two oil ports of the electro-hydraulic variable motor are respectively connected by pipelines to form a closed loop, and the output shaft end of the electro-hydraulic variable motor is connected to the reduction gear device wheel; The output oil port of the fixed-displacement hydraulic pump is connected to the oil inlet of the control valve by a pipeline, and the oil outlet of the control valve is connected to the oil inlet of the working hydraulic cylinder and / or the hydraulic motor.

[0008] The above-mentioned hydrostatic drive control system is characterized in that: the input end of the vehicle controller is further connected to the signal output end of the working mode selection switch of the loader, 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 end of the vehicle controller is further connected to the signal output end of the hand throttle knob of the loader.

[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 entering the working hydraulic cylinder and / or hydraulic motor is determined by the opening degree of the control valve. Electrically controlled closed-loop variable displacement pump The aforementioned hydrostatic drive control system is characterized in that: the operating speeds of the working hydraulic cylinder and the hydraulic motor are jointly controlled by the engine speed and the opening degree of the control valve. When the opening degree of the control valve is constant, the operating speed of the working hydraulic cylinder or the hydraulic motor is only controlled by the engine speed. A control method using the aforementioned hydrostatic drive control system includes the following steps: (1) Input corresponding selection signals to the vehicle controller through the mode selection switch and the FNR selection switch of the loader; (2) Transmit the output signals of the accelerator pedal and / or the hand throttle knob of the loader to the vehicle controller, If only one of the signals is transmitted to the vehicle controller, the vehicle controller converts the signal into an engine requested speed value and transmits it to the engine controller, If two corresponding signals are transmitted to the vehicle controller, the vehicle controller converts the two signals into two corresponding engine requested speed values, and takes the larger value and transmits it 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 a first displacement value of the electrically controlled closed-loop variable displacement pump based on the actual speed value; at the same time, the engine drives the fixed-displacement hydraulic pump to work at the actual speed value, and the output flow rate of the fixed-displacement hydraulic pump drives the working hydraulic cylinder and / or the hydraulic motor to actuate through the control valve; (4) Input a speed limit signal to the vehicle controller through the speed limiter knob, and the vehicle controller calculates the second displacement value of the electrically controlled closed-loop variable displacement 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 electrically controlled closed-loop variable displacement pump under the control of the speed limiter knob. The electrically controlled closed-loop variable displacement pump outputs flow into the electrically controlled variable motor at the actual displacement value, drives the electrically controlled variable motor to rotate, and then drives the vehicle to move through the reduction gear.

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

[0012] A control method for a hydrostatic drive control system as described above includes the following steps: (1) Input corresponding selection signals to the vehicle controller through the mode selection switch and FNR selection switch of the loader; (2) Transmit the output signal of the hand throttle knob of the loader to the vehicle controller, convert it into an engine requested speed value, and transmit it 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 a fixed-displacement hydraulic pump to work, and the output flow of the fixed-displacement hydraulic pump drives the working hydraulic cylinder and / or hydraulic motor to actuate through a control valve; (3) Transmit the output signal of the accelerator pedal of the loader to the vehicle controller, and the vehicle controller generates a first displacement value of the electro-hydraulic closed-loop variable pump from this signal; at the same time, transmit the output signal of the speed limiter knob of the loader to the vehicle controller, and the vehicle controller generates a third displacement value of the electro-hydraulic closed-loop variable pump from this 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 electro-hydraulic closed-loop variable pump under the combined control of the accelerator pedal and the speed limiter knob. The electro-hydraulic closed-loop variable pump outputs flow into the electro-hydraulic variable motor at this actual displacement value, drives the electro-hydraulic variable motor to rotate, and then drives the vehicle to move through a reduction gear.

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

[0014] A loader is configured with the hydrostatic drive control system as described above.

[0015] The beneficial effects of the present invention are: (1) Adopting the coupling control and separation control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump can not only achieve the follow-up control of the vehicle speed and the engine speed, but also achieve the separation control of the vehicle speed and the engine speed. And by adding a hand throttle knob, a speed limiter knob, and a working mode selection switch device, two working modes are formed; (2) The traveling system adopts an electro-hydraulic control system, and the working system adopts a hydraulic control system, which can achieve independent control of the traveling system and the working system, and meet the precise coordinated control of the vehicle speed and the action speed of the attachment under the conditions of short-distance loading operations and constant attachment flow; (3) Multi-stage proportional control of the displacement of the electro-hydraulic closed-loop variable pump realizes the limitation of any real-time vehicle speed, and solves the convenient control of vehicle speed requirements under different working conditions. Description of the Drawings

[0016] Figure 1It is a schematic diagram of a hydrostatic drive control system of the present invention; Figure 2 It is a schematic diagram of the working mode of the second embodiment of the present invention; Figure 3 It is a schematic diagram of the working mode of the third embodiment of the present invention; Among them, 1. Engine; 2. Engine controller; 3. Electrically controlled closed-loop variable pump; 4. Electrically controlled variable motor; 6. Reduction gear wheel; 8. Vehicle controller; 9. Accelerator pedal; 10. Manual throttle knob; 11. Speed limiter knob; 12. Working mode selection switch; 13. FNR selection switch; 14. Fixed-displacement hydraulic pump; 15. Control valve; 16. Working hydraulic cylinder; 17. Hydraulic motor. Detailed implementation manners

[0017] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices. Embodiment 1

[0019] Figure 1 It is a structural schematic diagram of a hydrostatic drive control system provided in Embodiment 1 of the present invention. This control system mainly includes a traveling system and a working system; the traveling system includes a vehicle controller 8, an engine controller 2, an engine 1, an electrically controlled closed-loop variable pump 3 and an electrically 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 end of the vehicle controller 8 is respectively connected to the input ends of the engine controller 2, the electronically controlled closed-loop variable pump 3, the electronically controlled variable motor 4, and the controller 15, and the input end of the vehicle controller 8 is connected to the output end of the engine controller 2 and the signal output ends of the accelerator pedal 9, the speed limiter knob 11, and the FNR selection switch 13 of the loader; 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 respectively connected to the input shaft ends of the electronically controlled closed-loop variable pump 3 and the fixed-displacement hydraulic pump 14; the two oil ports of the electronically controlled closed-loop variable pump 3 and the two oil ports of the electronically controlled variable motor 4 are respectively connected by pipelines to form a closed loop, and the output shaft end of the electronically controlled variable motor 4 is connected to the reduction gear device wheel 6. In this embodiment, the input end of the vehicle controller is further connected to the signal output end of the hand throttle knob 10 of the loader.

[0021] During the actual operation process, the travel system inputs an engine speed request signal to the vehicle controller 8 by the accelerator pedal 9 and / or the hand throttle knob 10, converts the request signal into the requested engine speed, and then transmits it to the engine controller 2. The engine controller 2 and the vehicle controller 8 are connected through CAN communication for engine requested speed control and engine actual speed feedback, and combined with the speed limit signal transmitted by the speed limiter knob 11 to the vehicle controller 8, an electric current signal for controlling the displacements of the electronically controlled closed-loop variable pump 3 and the electronically controlled variable motor 4 is output through the algorithm of the vehicle controller 8, so as to drive the reduction gear device wheel 6 to move at a corresponding speed, realizing the separate control of the vehicle speed and the engine speed.

[0022] For the working system part, the output oil port of the fixed-displacement hydraulic pump 14 is connected to the oil inlet of the control valve 15 by a pipeline, and the oil outlet of the control valve 15 is connected to the oil inlets of the working hydraulic cylinder 16 and / or the hydraulic motor 17. Since the displacement of the fixed-displacement hydraulic pump 14 is fixed, the output flow of the fixed-displacement hydraulic pump 14 is controlled by the engine speed. The flow rate of the output flow of the fixed-displacement hydraulic pump 14 entering the working hydraulic cylinder 16 and the hydraulic motor 17 through the control valve 15 is determined by the opening degree of the control valve. The action 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. When the opening degree of the control valve is certain, the action speed of the hydraulic cylinder or the hydraulic motor is only controlled by the engine speed.

[0023] Thus, the problems of poor coordination and complex operation between the vehicle speed and the operation speed of the attachments under the conditions of short-distance loading of the loader and constant attachment flow rate are solved. By multi-stage proportional control of the displacement of the electronically controlled closed-loop variable pump, the limitation of any real-time vehicle speed is realized, and the convenient control of the vehicle speed requirements under different working conditions is solved.

[0024] Electronically controlled closed-loop variable pump The input end of the vehicle controller is also connected to the signal output end of the working mode selection switch of the loader, and the working mode selection switch can provide at least two different working mode selection signals. In this embodiment, the hydrostatic drive control system can select two different working modes of coupling control and separation control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump according to needs through the working mode selection switch. Embodiment 2

[0025] As Figure 1 and Figure 2 shown, for a control method of a hydrostatic drive control system, when the vehicle controller 8 receives the signal of working mode 1 selected by the working mode selection switch 12 (that is, selecting the coupling control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump), the control method specifically includes the following steps: (1) Input the corresponding selection signal into the vehicle controller 8 through the FNR selection switch 13 of the loader. In this embodiment, the selection of the F signal is taken as an example for illustration; (2) Transmit the output signals of the accelerator pedal 9 and / or the hand throttle knob 10 of the loader 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 requested 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 requested speed values and takes the larger value of them 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 a first displacement value of the electro-hydraulic closed-loop 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 at this actual speed value, and 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 certain, 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 action speed of the hydraulic cylinder of the working system changes following the engine speed; (4) Input a speed limit signal into the vehicle controller 8 through the speed limiter knob 11, and calculate the second displacement value of the electro-hydraulic closed-loop variable pump corresponding to the speed limit signal by the vehicle controller 8; (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 electro-hydraulic closed-loop variable pump 3 under the control of the speed limiter knob 11. The electro-hydraulic closed-loop variable pump 3 outputs flow at this actual displacement value and enters the electro-hydraulic variable motor 4 to drive the electro-hydraulic variable motor 4 to rotate, and then drives the vehicle to move through the reduction gear.

[0026] In this embodiment, the speed limiter knob 11 is an operating device that will not automatically return to the initial position after being turned to a certain operating position. Its operating signal is input into the vehicle controller 8. Through a multi-stage proportional control method, the second displacement of the electro-hydraulic closed-loop variable pump 3 corresponding to the current engine speed is generated. It is defined that the initial position of the speed limiter knob 11 corresponds to the first displacement of the electro-hydraulic closed-loop variable pump 3 corresponding to any current engine speed, the end position of the speed limiter knob 11 corresponds to the displacement of the electro-hydraulic closed-loop variable pump 3 being zero, and each position in the middle of the speed limiter knob 11 corresponds to a second displacement of the electro-hydraulic closed-loop variable pump. By comparing the first displacement with 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. By selecting the smaller displacement value, the loader moves at the speed actually generated by the operator's actual operation of the accelerator pedal 9 and / or the hand throttle knob 10, 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 the hand throttle knob 10. By selecting the smaller value, the loader is controlled to move at the speed limited by the speed limiter knob 11), the displacement of the electro-hydraulic closed-loop variable pump generated at the current engine speed is controlled by the multi-stage proportional control of the speed limiter knob 11. When the current vehicle speed is restricted in real time, the engine speed is increased by operating the accelerator pedal 9 or the hand throttle knob 10. When the vehicle speed is restricted by the speed limiter knob 11, the flow rate of the fixed-displacement hydraulic pump 14 of the working system is increased, and thus the operating speed of the working hydraulic cylinder 16 is accelerated. This solves the problems of poor coordination between the vehicle speed and the operating speed of the working device during the short-distance loading condition of the loader, and the difficulty for the operator to step on the accelerator to accelerate the operating speed of the working device while stepping on the brake. Embodiment Three

[0027] As Figure 1 and Figure 3 shown, for a control method of a hydrostatic drive control system, when the vehicle controller 8 receives the signal that the working mode selection switch 12 selects the working mode 2 (i.e., selects the separate control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump), the specific steps of this control method are as follows: (1) Input the corresponding selection signal into the vehicle controller through the FNR selection switch 13 of the loader. In this embodiment, the selection of the F signal is taken as an example for illustration; (2) Transmit the output signal of the hand throttle knob 10 of the loader to the vehicle controller 8, convert it into the engine requested speed value, and transmit it 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 actuate through the control valve 15. When the opening of the control valve 15 is fixed, the rotation speed of the working hydraulic cylinder 16 and the hydraulic motor 17 is only determined by the engine speed controlled by the hand throttle knob; (3) Transmit the output signal of the accelerator pedal 9 of the loader to the vehicle controller 8, and the vehicle controller 8 generates the first displacement value of the electro-hydraulic closed-loop variable pump from this signal; at the same time, transmit the output signal of the speed limiter knob 11 of the loader to the vehicle controller 8, and the vehicle controller 8 generates the third displacement value of the electro-hydraulic closed-loop variable pump from this 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 electro-hydraulic closed-loop variable pump under the combined control of the accelerator pedal and the speed limiter knob. The electro-hydraulic closed-loop variable pump outputs flow into the electro-hydraulic variable motor at this actual displacement value, drives the electro-hydraulic variable motor to rotate, and then drives the vehicle to move through the reduction gear.

[0028] Thus, by controlling the engine speed with the hand throttle knob 10 and controlling the displacement of the electro-hydraulic closed-loop variable pump 3 with the accelerator pedal 9 and / or the speed limiter knob 11, separate control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump 3 is achieved, that is, the vehicle speed is separated from the engine speed, thereby realizing independent control of the traveling system and the working system.

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

[0030] At the same time, by locking the displacement of the electro-hydraulic closed-loop variable pump 3 with the speed limiter knob 11, the vehicle speed remains unchanged. It is also possible to increase the displacement of the electro-hydraulic closed-loop variable pump 3 by stepping on the accelerator pedal 9 to increase the traveling vehicle speed (by taking the larger value of the displacements generated from the signals of the speed limiter knob 11 and the accelerator pedal 9 as the actual displacement value of the current electro-hydraulic closed-loop variable pump under the combined control of the accelerator pedal and the speed limiter knob). When the accelerator pedal is released, the vehicle speed returns to the original vehicle speed, which can be used in working conditions where the operating speed of the attachment needs to be constant, such as the cleaning working condition.

[0031] From the comprehensive description of Embodiment 2 and Embodiment 3, it can be seen that the manual throttle knob 10 and the speed limiter knob 11 are operating devices that will not automatically return to the initial position after being turned to a certain operating position and released. In working mode 1, the manual throttle knob 10 can not only control the engine speed in working mode 1, but also indirectly control the displacement of the electro-hydraulic closed-loop variable pump 3. The speed limiter knob 11 performs multi-stage proportional control on the current displacement of the electro-hydraulic closed-loop variable pump. In working mode 2, the manual throttle knob 10 only controls the engine speed, and the speed limiter knob 11 generates the control displacement of the electro-hydraulic closed-loop variable pump 3. The functions of the manual throttle knob 10 and the speed limiter knob 11 are different in different working modes. Embodiment 4

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

[0033] It should be noted that: The present invention is based on adding a manual throttle knob, a speed limiter knob, and a working mode selection switch, and combining the accelerator pedal to control the engine speed and the displacement of the electro-hydraulic closed-loop variable pump, forming two working modes of coupling and separation control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump. Among them, the manual throttle knob and the speed limiter knob can be replaced with any analog switch; in this patent, the manual throttle knob controls and locks the engine speed, and the real-time engine speed can also be locked through a switch button. By using two switch buttons, each press increases or decreases the fixed engine speed respectively to achieve engine speed control; in this patent, the engine speed and the displacement of the electro-hydraulic closed-loop variable pump are linearly coupled, and the engine speed and the displacement of the electro-hydraulic closed-loop variable pump can also be non-linearly coupled. Any coupling and separation control of the engine speed and the displacement of the electro-hydraulic closed-loop variable pump formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present 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 the engine speed and the displacement of the electro-hydraulic closed-loop variable pump under different operating conditions, which can not only achieve the follow-up control of the vehicle speed and the engine speed, but also achieve the separation control of the vehicle speed and the engine speed.

[0035] The above shows and describes 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 by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the protection scope of the claimed present invention. The protection scope required by the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydrostatic drive control system, characterized in that: It includes a traveling system and a working system; The traveling system includes a vehicle controller, an engine controller, an engine, an electronically controlled closed-loop variable displacement pump, and an electronically controlled variable displacement motor; The working system includes a fixed displacement hydraulic pump, a control valve, a working hydraulic cylinder, and a hydraulic motor; where The output end of the vehicle controller is respectively connected to the input ends of the engine controller, the electronically controlled closed-loop variable displacement pump, the electronically controlled variable displacement motor, and the control valve, and the input end of the vehicle controller is connected to the output end of the engine controller and the signal output ends of the throttle pedal, speed limiter knob, and FNR selection switch of the loader; 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 respectively connected to the input shaft ends of the electronically controlled closed-loop variable displacement pump and the fixed displacement hydraulic pump; The two oil ports of the electronically controlled closed-loop variable displacement pump and the two oil ports of the electronically controlled variable displacement motor are respectively connected by pipelines to form a closed-loop circuit, and the output shaft end of the electronically controlled variable displacement motor is connected to the reduction gear device wheel; The output oil port of the fixed displacement hydraulic pump is connected to the oil inlet of the control valve by a pipeline, and the oil outlet of the control valve is connected to the oil inlets of the working hydraulic cylinder and / or the hydraulic motor.

2. The hydrostatic drive control system according to claim 1, characterized in that: The input end of the vehicle controller is further connected to the signal output end of the working mode selection switch of the loader, and the working mode selection switch provides at least two different working mode selection signals.

3. The hydrostatic drive control system according to claim 1, characterized in that: The input end of the vehicle controller is further connected to the signal output end of the manual throttle knob of the loader.

4. A hydrostatic drive control system according to claim 1, wherein: The output flow of the fixed displacement hydraulic pump is controlled by the engine speed, and the flow rate of the fixed displacement hydraulic pump entering the working hydraulic cylinder and / or the hydraulic motor is determined by the opening of the control valve.

5. The hydrostatic drive control system according to claim 4, characterized in that: The action 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 action speed of the working hydraulic cylinder or the hydraulic motor is only controlled by the engine speed.

6. A control method for a hydrostatic drive control system according to any one of claims 1-5, characterized in that: It includes the following steps: (1) Input the corresponding selection signals to the vehicle controller through the mode selection switch and FNR selection switch of the loader; (2) Transmit the output signals of the throttle pedal and / or the manual throttle knob of the loader to the vehicle controller. If only one of the signals is transmitted to the vehicle controller, the vehicle controller converts the signal into an engine requested speed value and transmits it to the engine controller. If two corresponding signals are transmitted to the vehicle controller, the vehicle controller converts the two signals into two corresponding engine requested speed values, and takes the larger value and transmits it 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 a first displacement value of the electronically controlled closed-loop variable displacement pump based on the actual speed value; at the same time, the engine drives the fixed displacement hydraulic pump to work at this actual speed value, and the output flow of the fixed displacement hydraulic pump drives the working hydraulic cylinder and / or the hydraulic motor to act through the control valve; (4) Input a speed limit signal to the vehicle controller through the speed limiter knob, and calculate the second displacement value of the electronically controlled closed-loop variable displacement pump corresponding to the speed limit signal by the vehicle controller; (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 electro-hydraulic closed-loop variable pump under the control of the speed limiter knob. The electro-hydraulic closed-loop variable pump outputs flow at this actual displacement value to enter the electro-hydraulic variable motor, driving the electro-hydraulic variable motor to rotate, and then driving the vehicle to move through the reduction gear.

7. The control method of a hydrostatic drive control system according to claim 6, characterized in that: In step (3), with the control valve opening fixed, the action speed of the working hydraulic cylinder and / or the hydraulic motor changes following the engine speed controlled by the accelerator pedal and the hand throttle knob.

8. A control method for a hydrostatic drive control system according to any one of claims 1-5, characterized in that: It includes the following steps: (1) Input the corresponding selection signals into the vehicle controller through the mode selection switch and the FNR selection switch of the loader; (2) Transmit the output signal of the hand throttle knob of the loader to the vehicle controller, convert it into an engine requested speed value, and transmit it 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, and the fixed-displacement hydraulic pump outputs flow to drive the working hydraulic cylinder and / or the hydraulic motor to act through the control valve; (3) Transmit the output signal of the accelerator pedal of the loader to the vehicle controller, and the vehicle controller generates the first displacement value of the electro-hydraulic closed-loop variable pump from this signal; at the same time, transmit the output signal of the speed limiter knob of the loader to the vehicle controller, and the vehicle controller generates the third displacement value of the electro-hydraulic closed-loop variable pump from this 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 electro-hydraulic closed-loop variable pump under the joint control of the accelerator pedal and the speed limiter knob. The electro-hydraulic closed-loop variable pump outputs flow at this actual displacement value to enter the electro-hydraulic variable motor, driving the electro-hydraulic variable motor to rotate, and then driving the vehicle to move through the reduction gear.

9. The control method of a hydrostatic drive control system according to claim 8, characterized in that: In step (2), with the control valve opening fixed, the action speed of the working hydraulic cylinder and / or the hydraulic motor changes following the engine speed controlled by the hand throttle knob.

10. A loader, characterized in that: The loader is configured with the hydrostatic drive control system described in any one of claims 1-5.

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