Closed motor hydraulic circuit and control method therefor, and work machine

Abstract

The present application belongs to the technical field of hydraulics, and specifically relates to a closed motor hydraulic circuit and a control method therefor, and a work machine. The closed motor hydraulic circuit comprises a hydraulic motor, a hydraulic pump and a motor bypass oil circuit, wherein the motor bypass oil circuit connects an oil inlet end of the hydraulic motor to an oil outlet end of the hydraulic motor, and is provided with a regulating valve configured to control the flow rate of the motor bypass oil circuit. The control method for the closed motor hydraulic circuit comprises the following steps: acquiring a speed control instruction of a hydraulic motor; when a speed value corresponding to the speed control instruction is greater than a preset speed, adjusting the rotating speed of the hydraulic motor, and limiting the pressure at an oil inlet end of the hydraulic motor by means of controlling a regulating valve; and when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, adjusting the rotating speed of the hydraulic motor. By using the control method for the closed motor hydraulic circuit, the rotating speed of the hydraulic motor and the pressure at the oil inlet end of the hydraulic motor can be accurately and stably adjusted.

Description

Closed motor hydraulic circuit and control method thereof, and working machine

[0001] Cross-reference to Related Applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411093162.4, filed August 9, 2024, the contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application belongs to the technical field of hydraulic technology, and particularly relates to a closed motor hydraulic circuit and a control method thereof, and a working machine. BACKGROUND

[0004] With the development of working machine technology, during the precise positioning stage of large load hoisting, millimeter / second level low-speed fine adjustment is required. The pump-controlled motor system in the prior art mainly controls the speed of the hydraulic motor based on the speed control instruction, and collects the hydraulic motor speed in real time. The output displacement of the hydraulic pump is adjusted based on the hydraulic motor speed to adjust the hydraulic motor speed in real time. However, the hydraulic motor speed is affected by different factors to different degrees under different working conditions, resulting in poor control accuracy of the hydraulic motor speed. SUMMARY

[0005] The purpose of the present application is to provide a closed motor hydraulic circuit and a control method thereof, and a working machine, to accurately and stably adjust the speed of the hydraulic motor and the pressure at the oil inlet end of the hydraulic motor.

[0006] To achieve the above-mentioned purpose, the present application provides a control method of a closed motor hydraulic circuit.

[0007] In some embodiments, the closed motor hydraulic circuit comprises a hydraulic motor, a hydraulic pump, and a motor bypass oil path connecting the oil inlet end of the hydraulic motor and the oil outlet end of the hydraulic motor and provided with an adjusting valve for controlling the flow of the motor bypass oil path. The control method of the closed motor hydraulic circuit comprises the following steps:

[0008] Obtaining a speed control instruction of the hydraulic motor;

[0009] In the case where the speed value corresponding to the speed control instruction is greater than a preset speed, adjusting the speed of the hydraulic motor and limiting the pressure at the oil inlet end of the hydraulic motor by controlling the adjusting valve;

[0010] In the case where the speed value corresponding to the speed control instruction is less than or equal to the preset speed, adjusting the speed of the hydraulic motor.

[0011] In some embodiments, when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the step of adjusting the rotating speed of the hydraulic motor comprises: determining a first flow rate according to the speed control instruction when the speed value corresponding to the speed control instruction is less than or equal to the preset speed; and determining the output flow rate of the hydraulic pump according to the first flow rate, so as to adjust the rotating speed of the hydraulic motor by adjusting the output flow rate of the hydraulic pump.

[0012] In some embodiments, the step of determining the output flow rate of the hydraulic pump according to the first flow rate comprises: determining a second flow rate according to the speed control instruction and a first preset correspondence relationship, the second flow rate being a bypass overflow flow rate of the adjusting valve, and the first preset correspondence relationship being a correspondence relationship between the speed control instruction and the second flow rate; and determining the output flow rate of the hydraulic pump according to the second flow rate and the first flow rate.

[0013] In some embodiments, the step of determining the output flow rate of the hydraulic pump according to the second flow rate and the first flow rate comprises: determining a third flow rate according to the pressure value at the oil inlet end of the hydraulic motor, the third flow rate being a leakage amount of the hydraulic motor; and determining the output flow rate of the hydraulic pump according to the first flow rate, the second flow rate and the third flow rate.

[0014] In some embodiments, the closed hydraulic motor circuit further comprises a rotating speed sensor for detecting an actual rotating speed of the hydraulic motor, and when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the step of adjusting the rotating speed of the hydraulic motor further comprises the following steps: acquiring the actual rotating speed of the hydraulic motor when the speed value corresponding to the speed control instruction is less than or equal to the preset speed; and determining a first opening degree control signal of the adjusting valve according to the actual rotating speed and the speed control instruction, the first opening degree control signal being used to adjust the opening degree of the adjusting valve so as to adjust the rotating speed of the hydraulic motor.

[0015] In some embodiments, when the speed value corresponding to the speed control instruction is greater than the preset speed, the step of adjusting the rotating speed of the hydraulic motor and limiting the pressure at the oil inlet end of the hydraulic motor by controlling the adjusting valve comprises the following steps: acquiring the pressure value at the oil inlet end of the hydraulic motor and the pressure value at the oil outlet end of the hydraulic motor in real time; determining an opening set pressure value of the adjusting valve according to the speed value corresponding to the speed control instruction, the pressure value at the oil outlet end of the hydraulic motor and a second preset correspondence relationship, wherein the second preset correspondence relationship is a correspondence relationship among the speed value corresponding to the speed control instruction, the pressure value at the oil outlet end of the hydraulic motor and the opening set pressure value of the adjusting valve; and opening the adjusting valve to reduce the pressure value at the oil inlet end of the hydraulic motor when the pressure value at the oil inlet end of the hydraulic motor is greater than the opening set pressure value.

[0016] In some embodiments, the step of opening a regulating valve to reduce the pressure at the inlet of the hydraulic motor when the pressure at the inlet of the hydraulic motor is greater than the opening set pressure value includes: determining the pressure difference between the pressure at the inlet of the hydraulic motor and the opening set pressure value; determining a second opening control signal for the regulating valve based on the pressure difference, the second opening control signal being used to adjust the opening of the regulating valve to adjust the pressure at the inlet of the hydraulic motor.

[0017] In some embodiments, the closed-loop motor hydraulic circuit further includes a speed sensor for detecting the actual speed of the hydraulic motor. When the speed value corresponding to the speed control command is greater than the preset speed, the speed of the hydraulic motor is adjusted, and the pressure at the oil inlet end of the hydraulic motor is limited by controlling the regulating valve. The circuit also includes the following steps: when the speed value corresponding to the speed control command is greater than the preset speed, the actual speed of the hydraulic motor is obtained; and the output flow of the hydraulic pump is adjusted according to the actual speed and the speed control command.

[0018] A second aspect of this application provides a closed-loop motor hydraulic circuit, comprising:

[0019] Hydraulic motor;

[0020] A hydraulic pump is used to drive a hydraulic motor to rotate.

[0021] The motor bypass oil circuit connects the oil inlet end of the hydraulic motor to the oil outlet end of the hydraulic motor and is equipped with a regulating valve for controlling the flow rate of the motor bypass oil circuit.

[0022] And the controller is configured to execute the control method of the closed motor hydraulic circuit described above.

[0023] A third aspect of this application provides a working machine, including the aforementioned closed-loop motor hydraulic circuit.

[0024] In the technical solution, when the speed control instruction for the hydraulic motor is obtained, it is determined whether the speed value corresponding to the speed control instruction is greater than a preset speed. If the speed value corresponding to the speed control instruction is greater than the preset speed, the rotation speed of the hydraulic motor is adjusted, and the pressure at the oil inlet end of the hydraulic motor is limited by controlling the adjusting valve of the motor bypass oil path. By using the method, the speed of the high-speed hydraulic motor can be controlled, and the system impact pressure can be reduced to protect the hydraulic circuit. If the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the rotation speed of the hydraulic motor is adjusted to accurately rotate the hydraulic motor in a low-speed state. In other words, by using the method, different hydraulic control strategies can be adopted for the hydraulic motor according to the rotation speed condition of the hydraulic motor, which helps the hydraulic motor better cope with the influence of external factors, and thus accurate rotation speed control is achieved.

[0025] Other features and advantages of the present application will be illustrated in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with the specific embodiments described below, but do not constitute a limitation on the present application. For those skilled in the art, other drawings can be obtained from the structures shown in the drawings without creative labor. In the drawings:

[0027] Fig. 1 is a flowchart of a control method of a closed motor hydraulic circuit according to an embodiment of the present application;

[0028] Fig. 2 is a hydraulic principle diagram of a closed motor hydraulic circuit according to an embodiment of the present application;

[0029] Fig. 3 is a control flowchart of a low-speed working mode of a hydraulic motor according to an embodiment of the present application;

[0030] Fig. 4 is a control flowchart of a low-speed working mode of a hydraulic motor according to a specific embodiment of the present application;

[0031] Fig. 5 is a rotation speed control flowchart of a hydraulic motor in a high-speed working mode according to an embodiment of the present application;

[0032] Fig. 6 is a pressure control flowchart of an oil inlet end of a hydraulic motor in a high-speed working mode according to an embodiment of the present application;

[0033] Fig. 7 is a flowchart of pressure control and rotation speed control of an oil inlet end of a hydraulic motor in a high-speed working mode according to a specific embodiment of the present application.

[0034] Explanation of Reference Numerals 1 Hydraulic pump 5 Overflow valve 2.1 First overflow oil supply valve 6 Hydraulic oil tank 2.2 Second overflow oil supply valve 7 Regulating valve 3 Oil supply pump A Inlet port end of hydraulic motor 4 Hydraulic motor B Outlet port end of hydraulic motor DETAILED DESCRIPTION

[0035] The specific embodiments of the present application will be described below in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0036] A control method of a closed motor hydraulic circuit, a closed motor hydraulic circuit and a working machine according to the present application are described below with reference to the accompanying drawings. As shown in FIG. 1, a flow chart of a control method of a closed motor hydraulic circuit according to an embodiment of the present application is provided; as shown in FIG. 2, a hydraulic principle diagram of a closed motor hydraulic circuit according to an embodiment of the present application is provided. The closed motor hydraulic circuit includes a hydraulic motor 4, a hydraulic pump 1 and a motor bypass oil passage connecting an inlet port end A of the hydraulic motor with an outlet port end B of the hydraulic motor and provided with a regulating valve 7 for controlling the flow of the motor bypass oil passage, and the control method of the closed motor hydraulic circuit includes the following steps:

[0037] S102, obtaining a speed control instruction of the hydraulic motor 4.

[0038] S104, in a case where a speed value corresponding to the speed control instruction is greater than a preset speed, adjusting the rotational speed of the hydraulic motor 4 and limiting the pressure at the inlet port end A of the hydraulic motor by controlling the regulating valve 7.

[0039] S106, in a case where the speed value corresponding to the speed control instruction is less than or equal to the preset speed, adjusting the rotational speed of the hydraulic motor 4.

[0040] The closed motor hydraulic circuit is a closed hydraulic circuit containing a hydraulic motor 4, and the hydraulic oil in the closed hydraulic circuit continuously flows in the circuit to form a closed loop. The closed hydraulic circuit improves the efficiency and energy utilization of the system by recycling the hydraulic oil. The hydraulic motor 4 can convert the hydraulic energy in the closed motor hydraulic circuit into mechanical energy to drive external components to rotate or move. The closed motor hydraulic circuit of the present application includes a motor bypass oil path connecting the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor, and an adjusting valve 7 is arranged on the motor bypass oil path for controlling the flow of the motor bypass oil path. By adjusting the valve opening of the adjusting valve 7, the flow of the motor bypass oil path can be adjusted, which can affect the hydraulic oil pressure and flow entering the hydraulic motor 4, thereby adjusting the speed of the hydraulic motor 4 and the pressure of the oil inlet of the hydraulic motor 4.

[0041] Specifically, when adjusting the closed motor hydraulic circuit, the controller (not shown in the figure) can control the closed motor hydraulic circuit. First, the controller can obtain a speed control instruction for the hydraulic motor 4. If the speed value corresponding to the speed control instruction is greater than the preset speed, it is determined that the hydraulic motor 4 is in high-speed working mode. If the speed value corresponding to the speed control instruction is less than or equal to the preset speed, it is determined that the hydraulic motor 4 is in low-speed working mode. When the hydraulic motor 4 is in high-speed working mode, the controller can adjust the speed of the hydraulic motor 4 to prevent the speed of the hydraulic motor 4 from deviating too much. Moreover, during high-speed rotation of the hydraulic motor 4, the oil inlet pressure of the hydraulic motor 4 may surge, and the controller can control the adjusting valve 7 to open to reduce the pressure of the oil inlet end A of the hydraulic motor to protect the hydraulic elements in the closed motor hydraulic circuit. When the hydraulic motor 4 is in low-speed working mode, the controller can control the speed of the hydraulic motor 4 to rotate accurately.

[0042] Using the above-mentioned control method of the closed motor hydraulic circuit, when the hydraulic motor 4 is in high-speed working mode, the controller can adjust the pressure of the oil inlet end A of the hydraulic motor during high-speed rotation of the hydraulic motor 4, and can control the speed of the hydraulic motor 4; when the hydraulic motor 4 is in low-speed working mode, the controller can accurately adjust the speed of the hydraulic motor 4 to make the hydraulic motor 4 work smoothly.

[0043] In the first embodiment, in the case that the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the step of adjusting the rotating speed of the hydraulic motor 4 comprises: in the case that the speed value corresponding to the speed control instruction is less than or equal to the preset speed, determining a first flow rate according to the speed control instruction; determining the output flow rate of the hydraulic pump 1 according to the first flow rate, so as to adjust the rotating speed of the hydraulic motor 4 by adjusting the output flow rate of the hydraulic pump 1. After obtaining the speed control instruction, the controller can determine the first flow rate according to the control instruction, wherein the first flow rate is the flow rate required for the rotating speed of the hydraulic motor 4 to reach the speed value corresponding to the speed control instruction. The controller can control the hydraulic pump 1 to output the corresponding flow rate, so as to adjust the rotating speed of the hydraulic motor 4. The hydraulic pump 1 can adjust the flow rate of the hydraulic oil output by the hydraulic pump 1 according to the control instruction output by the controller. The hydraulic pump 1 can be a variable pump or a fixed displacement pump driven by a variable motor.

[0044] In a specific embodiment, the output flow rate of the hydraulic pump 1 is proportional to the rotating speed of the hydraulic motor 4. By determining the proportional coefficient between the rotating speed of the hydraulic motor 4 and the output flow rate of the hydraulic pump 1, the output flow rate of the hydraulic pump 1 can be accurately adjusted. For example, the hydraulic pump 1 is a variable pump. After determining the output flow rate of the hydraulic pump 1, the controller outputs a control signal to the variable pump, so as to adjust the variable mechanism of the variable pump. The variable mechanism changes the swing angle, so that the variable pump can output the corresponding flow rate of the hydraulic oil according to the control signal.

[0045] In the second embodiment, determining the output flow of the hydraulic pump 1 according to the first flow includes: determining the second flow according to the speed control instruction and the first preset correspondence relationship, the second flow being the bypass overflow flow of the regulating valve 7, the first preset correspondence relationship being the correspondence relationship between the speed control instruction and the second flow; and determining the output flow of the hydraulic pump 1 according to the first flow and the second flow. The regulating valve 7 is a hydraulic valve capable of adjusting the valve opening of the regulating valve 7 according to a received control signal, thereby realizing proportional and accurate adjustment of the flow of hydraulic oil. The regulating valve 7 is connected with the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor. When the hydraulic motor 4 is working, part of the hydraulic oil will flow into the regulating valve 7 through the motor bypass oil circuit. Among the hydraulic oil flowing into the regulating valve 7, there will be a part of the hydraulic oil overflowing from the regulating valve 7. Therefore, when the speed of the hydraulic motor 4 is adjusted by the hydraulic pump 1, the hydraulic oil overflowing from the regulating valve 7 should be considered. There is a first preset correspondence relationship between the hydraulic flow overflowing at the regulating valve 7 and the speed value corresponding to the speed control instruction. The controller can determine the second flow according to the first preset correspondence relationship and the speed control instruction, wherein the second flow is the bypass overflow flow of the regulating valve 7. Therefore, the output flow of the hydraulic pump 1 can be determined according to the first flow and the second flow. The first preset correspondence relationship can be a formula, a table or other. Compared with the demand flow of the hydraulic motor 4 determined in the first embodiment, the second embodiment considers the hydraulic oil overflowing from the regulating valve 7 and can more accurately adjust the speed of the hydraulic motor 4.

[0046] In a specific embodiment, the regulating valve 7 is an electric proportional regulating valve. Compared with other forms of hydraulic regulating valves, the electric proportional regulating valve can simply adjust the throttling area of the valve body according to the current input to the electric proportional regulating valve, and has simple structure, accurate adjustment and fast response.

[0047] In another specific embodiment, the regulating valve 7 is an electric control regulating valve, which can adjust the throttling area according to the control signal input to the electric control regulating valve.

[0048] In addition, the regulating valve 7 can also be an adjustable overflow valve, which can change the overflow value according to the current input to the adjustable overflow valve, thereby adjusting the pressure and flow of the hydraulic motor 4.

[0049] In the third embodiment, the output flow rate of the hydraulic pump 1 is determined according to the second flow rate and the first flow rate, including: determining the third flow rate according to the pressure value of the oil inlet end A of the hydraulic motor, the third flow rate being the leakage amount of the hydraulic motor 4; determining the output flow rate of the hydraulic pump 1 according to the first flow rate, the second flow rate, and the third flow rate. During the operation of the hydraulic motor 4, there is a certain leakage amount at the hydraulic motor 4, so when the output flow rate of the hydraulic pump 1 is adjusted to adjust the speed of the hydraulic motor 4, the leakage amount of the hydraulic oil at the hydraulic motor 4 should be considered. The leakage amount of the hydraulic motor 4 is related to the pressure of the oil inlet end A of the hydraulic motor, so according to the pressure of the oil inlet end A of the hydraulic motor, the leakage amount of the hydraulic oil at the hydraulic motor 4 can be determined. The controller can determine the third flow rate according to the pressure value of the oil inlet end A of the hydraulic motor, the third flow rate being the leakage amount of the hydraulic motor 4. Further, the controller can determine the output flow rate of the hydraulic pump 1 according to the above-mentioned first flow rate, second flow rate, and third flow rate, to accurately adjust the speed of the hydraulic motor 4. In the third embodiment, the output flow rate of the hydraulic pump 1 is determined according to the leakage amount of the hydraulic motor 4, the required flow rate of the hydraulic motor 4, and the overflow flow rate of the adjusting valve 7, which is more accurate than the output flow rate of the hydraulic pump 1 determined in the second embodiment, so as to enable the controller to more accurately adjust the speed of the hydraulic motor 4.

[0050] In a specific embodiment, the controller can determine the output flow rate of the hydraulic pump 1 according to formula (1): V=k2P+k3ω+k4ω in (1)

[0051] wherein V is the output flow rate of the hydraulic pump 1, k2 is the equivalent leakage coefficient of the hydraulic motor 4, k3 is the equivalent displacement coefficient of the hydraulic motor 4, k4 is the bypass damping coefficient of the adjusting valve 7, P in is the pressure value of the oil inlet end A of the hydraulic motor, ω is the speed value corresponding to the speed control command, k3ω is the first flow rate, k4ω is the second flow rate, and k2P in is the third flow rate.

[0052] In the fourth embodiment, the closed motor hydraulic circuit further comprises a rotating speed sensor (not shown in the figure) for detecting the actual rotating speed of the hydraulic motor 4, and the step of adjusting the rotating speed of the hydraulic motor 4 in the case that the speed value corresponding to the speed control instruction is less than or equal to the preset speed further comprises the following steps: acquiring the actual rotating speed of the hydraulic motor 4 in the case that the speed value corresponding to the speed control instruction is less than or equal to the preset speed; and determining the first opening degree control signal of the adjusting valve 7 according to the actual rotating speed and the speed control instruction, the first opening degree control signal being used to adjust the opening degree of the adjusting valve 7 to adjust the rotating speed of the hydraulic motor 4. The rotating speed sensor can be used to determine the rotating speed of the hydraulic motor 4, and the controller can acquire the actual rotating speed of the hydraulic motor 4 in the case that the speed value corresponding to the speed control instruction is less than or equal to the preset speed, and compare the actual rotating speed with the speed value corresponding to the speed control instruction, and the controller can determine the first adjusting current of the electric proportional adjusting valve according to the difference between the actual rotating speed and the speed value corresponding to the speed control instruction. The adjusting valve 7 is arranged on the motor bypass oil path and is used to adjust the flow of the motor bypass oil path, and when the flow of the motor bypass oil path changes, the flow and pressure of the hydraulic oil flowing into the hydraulic motor 4 also change, thereby the rotating speed of the hydraulic motor 4 can be adjusted. The rotating speed sensor can detect the actual rotating speed of the hydraulic motor 4, and when there is a difference between the actual rotating speed and the speed value corresponding to the speed control instruction, the controller can control the adjusting valve 7 to adjust the flow of the hydraulic motor 4, thereby the rotating speed of the hydraulic motor 4 can be adjusted.

[0053] In one embodiment, the adjusting valve 7 is an electric proportional adjusting valve, which can adjust the opening degree of the valve 7 according to the first opening degree control signal, thereby adjusting the rotating speed of the hydraulic motor 4. The controller determines the first adjusting current of the electric proportional adjusting valve according to the pressure difference between the inlet and outlet of the hydraulic motor 4, the speed control instruction and a preset third corresponding relationship, and delivers the first adjusting current to the electric proportional adjusting valve. The preset third corresponding relationship can be a formula, a table or other. After the electric proportional adjusting valve is opened according to the first adjusting current, the rotating speed sensor acquires the actual rotating speed of the hydraulic motor 4 and transmits the detection value to the controller. The controller compares the actual rotating speed with the speed value corresponding to the speed control instruction, and performs PID adjustment on the first adjusting current of the electric proportional adjusting valve, so that the actual rotating speed of the hydraulic motor 4 is adjusted to the speed value corresponding to the speed control instruction.

[0054] In a specific embodiment, the first adjusting current of the electric proportional adjusting valve can be determined according to the following formula (2):

[0055] wherein I1 is the first adjusting current, k4 is the bypass damping coefficient of the electric proportional adjusting valve, k5 is the current-displacement coefficient of the electric proportional adjusting valve, ω is the speed value corresponding to the speed control instruction, C is the flow coefficient, ρ is the density of the hydraulic oil, P is the pressure of the hydraulic oil, and A is the cross-sectional area of the motor bypass oil path. d in ​P is the pressure value of the oil inlet end A of the hydraulic motor out P is the pressure value of the oil outlet end B of the hydraulic motor.

[0056] In one embodiment, as shown in FIG. 3, a control flow chart of the low-speed working mode of the hydraulic motor 4 provided according to the embodiments of the present application is provided. Step S103 includes the following detailed steps: S202, acquiring the pressures of the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor in real time. S204, determining the required flow of the hydraulic motor 4 when the hydraulic pump 1 is at the speed value corresponding to the speed control instruction. S206, the controller controls the hydraulic pump 1 to output the required flow, so that the hydraulic motor 4 rotates at the speed value corresponding to the speed control instruction. S208, determining the first regulating current of the electric proportional regulating valve according to the pressure of the oil inlet end A of the hydraulic motor, the pressure of the oil outlet end B of the hydraulic motor, and the speed value corresponding to the speed control instruction. S210, according to the first regulating current, the electric proportional regulating valve is controlled to open and adjust the rotating speed of the hydraulic motor 4. S212, comparing the actual rotating speed of the hydraulic motor 4 with the rotating speed corresponding to the speed control instruction, and adjusting the regulating current of the electric proportional regulating valve according to the comparison result, so that the hydraulic motor 4 accurately rotates at the rotating speed corresponding to the speed control instruction.

[0057] In one specific embodiment, as shown in FIG. 4, a control flow chart of the low-speed working mode of the hydraulic motor 4 provided according to the specific embodiments of the present application is provided. The regulating valve 7 is an electric proportional reversing valve. When the hydraulic motor 4 is in the low-speed working mode, the controller can acquire the rotating speed instruction of the hydraulic motor 4 and the hydraulic oil pressures of the two oil ports of the hydraulic motor 4, and compare the pressures of the two oil ports to determine the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor. The output flow of the variable pump is determined according to the above formula (1), and the swing angle γ of the variable pump is adjusted. The regulating current of the electric proportional reversing valve is determined according to the above formula (2), and the regulating current of the electric proportional reversing valve is adjusted. The actual rotating speed of the hydraulic motor 4 is acquired, and the regulating current of the electric proportional reversing valve is PID adjusted according to the difference between the rotating speed control instruction and the actual rotating speed. The electric proportional reversing valve can adjust the valve opening or perform the reversing operation according to the electric proportion.

[0058] In one embodiment, when the speed value corresponding to the speed control instruction is greater than the preset speed, the speed of the hydraulic motor 4 is adjusted, and the pressure of the oil inlet end A of the hydraulic motor is limited by controlling the adjusting valve 7, including the following steps: obtaining the pressure values of the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor in real time; determining the opening set pressure value of the adjusting valve 7 according to the speed value corresponding to the speed control instruction, the pressure value of the oil outlet end B of the hydraulic motor, and a second preset corresponding relationship, wherein the second preset corresponding relationship is the corresponding relationship among the speed value corresponding to the speed control instruction, the pressure value of the oil outlet end B of the hydraulic motor, and the opening set pressure value of the adjusting valve 7; and opening the adjusting valve 7 to reduce the pressure value of the oil inlet end A of the hydraulic motor when the pressure value of the oil inlet end A of the hydraulic motor is greater than the opening set pressure value. When the speed value corresponding to the speed control instruction is greater than the preset speed, the hydraulic motor 4 is in a high-speed working mode. In the high-speed working mode, the pressure of the oil inlet end A of the hydraulic motor may be large during starting and braking, thereby causing damage to the closed motor hydraulic circuit. Therefore, when the pressure of the oil inlet end A of the hydraulic motor is greater than the opening set pressure value in the high-speed working mode of the hydraulic motor 4, the adjusting valve 7 can be opened to reduce the pressure of the oil inlet end A of the hydraulic motor.

[0059] Specifically, when it is determined that the speed value corresponding to the speed control instruction is greater than the preset speed, the controller obtains the pressure values of the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor in real time, and determines the opening set pressure value required for adjusting the pressure of the oil outlet end B of the hydraulic motor according to the speed value corresponding to the speed control instruction, the pressure value of the oil outlet end B of the hydraulic motor, and a second preset corresponding relationship. The second preset corresponding relationship is a formula, a table or other. When the pressure value of the oil inlet end A of the hydraulic motor is greater than the opening set pressure value, the controller can open the adjusting valve 7 to shunt the hydraulic oil in the closed motor hydraulic circuit, reduce the pressure of the oil inlet end A of the hydraulic motor, and protect the hydraulic components in the closed motor hydraulic circuit.

[0060] In one specific embodiment, the opening set pressure value can be obtained according to the following formula (3):

[0061] wherein P set is the opening set pressure value, k1 is a pressure impact coefficient, J m is the equivalent rotational inertia of the hydraulic motor 4 and the load, ω is the speed value corresponding to the speed control instruction, t is the response time requirement of the controller, B m is the viscous resistance coefficient of the hydraulic motor 4, T is the load torque of the hydraulic motor 4, V m is the displacement of the hydraulic motor 4, and P outPout is the pressure value of the oil outlet end B of the hydraulic motor. The response time requirement of the controller is related to the acquisition frequency or acquisition time interval of the controller itself.

[0062] In one embodiment, when the pressure value of the oil inlet end A of the hydraulic motor is greater than the opening set pressure value, the step of opening the regulating valve 7 to reduce the pressure value of the oil inlet end A of the hydraulic motor includes: determining the pressure difference between the pressure value of the oil inlet end A of the hydraulic motor and the opening set pressure value; determining a second opening degree control signal of the regulating valve 7 according to the pressure difference, the second opening degree control signal being used to adjust the opening degree of the regulating valve 7 to adjust the pressure of the oil inlet end A of the hydraulic motor. The motor bypass oil circuit can divert the hydraulic oil flowing into the hydraulic motor 4, and the greater the diversion flow, the smaller the pressure of the oil inlet end A of the hydraulic motor. The second opening degree control signal can control the regulating valve 7 to open the valve port according to the valve port opening degree corresponding to the second opening degree control signal. In the case where the regulating valve 7 needs to be opened to reduce the pressure of the oil inlet end A of the hydraulic motor, the controller can determine the valve port opening degree of the regulating valve 7 according to the pressure difference between the pressure value of the oil inlet end A of the hydraulic motor and the opening set pressure, and send a second opening degree control signal to the regulating valve 7. Wherein, the second opening degree control signal is a second regulating current, and the greater the current value of the second regulating current, the greater the valve port opening degree of the regulating valve 7. By using the above-mentioned control method of the closed motor hydraulic circuit, the pressure of the oil inlet end A of the hydraulic motor can be adjusted according to the difference between the opening set pressure and the pressure value of the oil inlet end A of the hydraulic motor when the pressure value of the oil inlet end A of the hydraulic motor is greater than the opening set pressure, the hydraulic oil is diverted to the minimum extent to ensure that the hydraulic oil pressure is within a safe range, and the hydraulic motor 4 is prevented from rotating too low due to pressure reduction, thereby affecting the work efficiency.

[0063] In a specific embodiment, the second opening degree control signal is a second regulating current, and the current value of the current signal is obtained according to the following formula (4): in -P set )+I de (4)

[0064] Wherein, I2 is the second regulating current, k2 is the equivalent leakage coefficient of the hydraulic motor 4, P in is the pressure value of the oil inlet end A of the hydraulic motor, P set is the opening set pressure value, and I de is a preset current coefficient.

[0065] In one specific embodiment, the controller only adjusts the pressure of the oil inlet end A of the hydraulic motor when the hydraulic motor 4 is started and stopped, so as to avoid excessive impact when the hydraulic motor 4 is started and stopped.

[0066] In one embodiment, the closed motor hydraulic circuit further comprises a rotating speed sensor for detecting the actual rotating speed of the hydraulic motor 4, and in the case that the speed value corresponding to the speed control instruction is greater than the preset speed, the rotating speed of the hydraulic motor 4 is adjusted, and the pressure of the oil inlet end A of the hydraulic motor is limited by controlling the adjusting valve 7. The method further comprises the following steps: in the case that the speed value corresponding to the speed control instruction is greater than the preset speed, the actual rotating speed of the hydraulic motor 4 is obtained; and the output flow of the hydraulic pump 1 is adjusted according to the actual rotating speed and the speed control instruction. In the high-speed working mode of the hydraulic motor 4, the actual rotating speed of the hydraulic motor 4 is easy to deviate from the speed value corresponding to the speed control instruction. The controller can obtain the actual rotating speed detected by the rotating speed sensor, compare it with the speed value corresponding to the speed control instruction, and adjust the output flow of the hydraulic pump 1 according to the comparison result to adjust the rotating speed of the hydraulic motor 4. By using the above-mentioned control method of the closed motor hydraulic circuit, the speed of the high-speed rotating hydraulic motor 4 can be adjusted, and the hydraulic motor 4 is prevented from deviating from the rotating speed corresponding to the speed control instruction, thereby affecting the working effect.

[0067] In one embodiment, the controller can perform PID adjustment on the output flow of the hydraulic pump 1 according to the actual rotating speed and the rotating speed corresponding to the speed control instruction, so that the hydraulic pump 1 outputs corresponding hydraulic oil to gradually approach the rotating speed of the hydraulic motor 4 to the speed value corresponding to the speed control instruction.

[0068] In one embodiment, the hydraulic pump 1 is a variable pump. FIG. 5 is a speed control flowchart of the hydraulic motor 4 in the high-speed working mode according to an embodiment of the present application. Step S102 comprises the following detailed steps: S302, the pressures of the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor are obtained in real time. S304, the required flow of the variable pump is determined according to the speed value corresponding to the speed control instruction. S306, the variable pump is controlled to adjust the swing angle of the variable pump according to the required flow. S308, after the hydraulic motor 4 starts to rotate, the swing angle of the hydraulic pump 1 is adjusted according to the actual rotating speed of the hydraulic motor 4 and the speed value corresponding to the speed control instruction to adjust the rotating speed of the hydraulic motor 4.

[0069] In addition, FIG. 6 is a pressure control flowchart of the oil inlet end of the hydraulic motor 4 in the high-speed working mode according to an embodiment of the present application. The adjusting valve 7 is an electric proportional adjusting valve. Step S102 further comprises the following detailed steps: S402, the opening set pressure of the electric proportional adjusting valve is determined according to the speed value corresponding to the speed control instruction and the oil outlet pressure value of the hydraulic motor 4. S404, in the case that the pressure of the oil inlet end A of the hydraulic motor is greater than the opening set pressure, the electric proportional adjusting valve is controlled to determine a second adjusting current according to the pressure difference between the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor. S406, the valve opening of the electric proportional adjusting valve is adjusted according to the second adjusting current to reduce the pressure of the oil inlet end A of the hydraulic motor.

[0070] In a specific embodiment, as shown in FIG. 7, a flow chart of the pressure control and speed control of the oil inlet end of the hydraulic motor 4 in the high-speed working mode according to the specific embodiment of the present application. The regulating valve 7 is an electric proportional directional valve, and the hydraulic pump 1 is a variable pump. When the hydraulic motor 4 is in the high-speed working mode, the controller can obtain the speed instruction of the hydraulic motor 4, the acquisition time interval t of the controller, and the hydraulic oil pressure of the two oil ports of the hydraulic motor 4, and compare the pressure of the two oil ports to determine the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor. According to the above formula (3), the opening set pressure value of the electric proportional directional valve is determined. When the hydraulic oil pressure of the oil inlet end A of the hydraulic motor is greater than the opening set pressure value, the second regulating current of the electric proportional directional valve is determined according to the above formula (4), and the current of the electric proportional directional valve is adjusted according to the second regulating current. When the hydraulic oil pressure of the oil inlet end A of the hydraulic motor is less than or equal to the opening set pressure value, the electric proportional directional valve is closed. In the embodiment of the present application, the speed of the hydraulic motor 4 can be determined in real time by the motor speed sensor, and the swing angle of the variable pump can be adjusted by PID according to the speed of the hydraulic motor 4 and the motor speed instruction, so as to accurately adjust the speed of the hydraulic motor 4.

[0071] The speed of the hydraulic motor 4 is adjusted by adjusting the flow of the hydraulic pump 1. In addition, when the pressure of the oil inlet end A of the hydraulic motor is greater than the opening set pressure, the controller can control the regulating valve 7 to open to reduce the pressure of the oil inlet end A of the hydraulic motor, so as to prevent the damage of the closed motor hydraulic circuit components caused by the excessively high pressure.

[0072] In an embodiment, the closed motor hydraulic circuit further comprises an oil supplement oil path, which can supplement the hydraulic oil overflowing from the hydraulic motor 4, the hydraulic pump 1 and the regulating valve 7, so as to prevent the cavitation of the hydraulic pump and the hydraulic motor.

[0073] In an embodiment, the oil supplement oil path comprises an oil supplement pump 3 and a plurality of overflow oil supplement valves. The oil supplement pump 3 is in communication with the hydraulic oil tank 6, and is used to deliver the hydraulic oil to the overflow oil supplement valves. The overflow oil supplement valves can deliver the hydraulic oil from the oil supplement oil path to the hydraulic pump 1, the hydraulic motor 4 or the regulating valve 7 in a one-way manner.

[0074] In a specific embodiment, the oil supplement oil path comprises a first overflow oil supplement valve 2.1 and a second overflow oil supplement valve 2.2. The first overflow oil supplement valve 2.1 and the second overflow oil supplement valve 2.2 supplement the two oil ports of the hydraulic pump 1 respectively.

[0075] In an embodiment, the oil supplement pump 3 is coaxially arranged with the hydraulic pump 1. The rotation of the hydraulic pump 1 can drive the oil supplement pump 3 to work. The working efficiency is high, the structure is simple, and it is easy to realize.

[0076] In one embodiment, the oil supplementing oil path further comprises an overflow valve 5, one end of the overflow valve 5 being in communication with the oil outlet end of the oil supplementing pump 3, and the other end of the overflow valve 5 being in communication with the hydraulic oil tank 6, the overflow valve 5 being used to prevent the hydraulic oil pressure in the oil supplementing oil path from being too high to cause damage to the hydraulic components in the closed motor hydraulic circuit.

[0077] The embodiment of the present application further provides a closed motor hydraulic circuit, comprising:

[0078] a hydraulic motor 4;

[0079] a hydraulic pump 1 used to drive the hydraulic motor 4 to rotate;

[0080] a motor bypass oil path connecting the oil inlet end A of the hydraulic motor with the oil outlet end B of the hydraulic motor and being provided with an adjusting valve 7 used to control the flow of the motor bypass oil path;

[0081] and a controller configured to execute the control method of the closed motor hydraulic circuit described above.

[0082] In one embodiment, a working machine is provided, comprising the closed motor hydraulic circuit described above.

[0083] In the description of the present application, it should be understood that the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0084] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected or can communicate with each other; can be directly connected, or can be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0085] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0086] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A control method of a closed motor hydraulic circuit, wherein, The closed motor hydraulic circuit comprises a hydraulic motor (4), a hydraulic pump (1) and a motor bypass oil path connecting an oil inlet end (A) of the hydraulic motor with an oil outlet end (B) of the hydraulic motor and provided with an adjusting valve (7) for controlling the flow of the motor bypass oil path, and the control method comprises the following steps: obtaining a speed control instruction of the hydraulic motor (4); adjusting the rotating speed of the hydraulic motor (4) when the speed value corresponding to the speed control instruction is greater than a preset speed, and limiting the pressure of the oil inlet end (A) of the hydraulic motor by controlling the adjusting valve (7); adjusting the rotating speed of the hydraulic motor (4) when the speed value corresponding to the speed control instruction is less than or equal to the preset speed.

2. The control method of a closed motor hydraulic circuit according to claim 1, wherein, The step of adjusting the rotating speed of the hydraulic motor (4) when the speed value corresponding to the speed control instruction is less than or equal to the preset speed comprises: determining a first flow according to the speed control instruction when the speed value corresponding to the speed control instruction is less than or equal to the preset speed; determining the output flow of the hydraulic pump (1) according to the first flow, so as to adjust the rotating speed of the hydraulic motor (4) by adjusting the output flow of the hydraulic pump (1).

3. The control method of a closed motor hydraulic circuit according to claim 2, wherein, The step of determining the output flow of the hydraulic pump (1) according to the first flow comprises: determining a second flow according to the speed control instruction and a first preset corresponding relationship, the second flow being the bypass overflow flow of the adjusting valve (7), and the first preset corresponding relationship being a corresponding relationship between the speed control instruction and the second flow; determining the output flow of the hydraulic pump (1) according to the second flow and the first flow.

4. The control method of a closed motor hydraulic circuit according to claim 3, wherein, The step of determining the output flow of the hydraulic pump (1) according to the second flow and the first flow comprises: determining a third flow according to the pressure value of the oil inlet end (A) of the hydraulic motor, the third flow being the leakage amount of the hydraulic motor (4); determining the output flow of the hydraulic pump (1) according to the first flow, the second flow and the third flow.

5. The control method of a closed motor hydraulic circuit according to any one of claims 1 to 4, wherein The closed motor hydraulic circuit further comprises a rotating speed sensor for detecting the actual rotating speed of the hydraulic motor (4), and the step of adjusting the rotating speed of the hydraulic motor (4) when the speed value corresponding to the speed control instruction is less than or equal to the preset speed further comprises the following steps: obtaining the actual rotating speed of the hydraulic motor (4) when the speed value corresponding to the speed control instruction is less than or equal to the preset speed; determining a first opening degree control signal of the adjusting valve (7) according to the actual rotating speed and the speed control instruction, the first opening degree control signal being used to adjust the opening degree of the adjusting valve (7) so as to adjust the rotating speed of the hydraulic motor (4).

6. The control method of a closed motor hydraulic circuit according to claim 1, wherein, The step of adjusting the rotating speed of the hydraulic motor (4) when the speed value corresponding to the speed control instruction is greater than a preset speed, and limiting the pressure of the oil inlet end (A) of the hydraulic motor by controlling the adjusting valve (7) comprises the following steps: acquire a pressure value of an oil inlet end (A) of the hydraulic motor and a pressure value of an oil outlet end (B) of the hydraulic motor in real time; determine an opening set pressure value of the regulating valve (7) according to a speed value corresponding to the speed control instruction, the pressure value of the oil outlet end (B) of the hydraulic motor, and a second preset corresponding relationship, wherein the second preset corresponding relationship is a corresponding relationship among the speed value corresponding to the speed control instruction, the pressure value of the oil outlet end (B) of the hydraulic motor, and the opening set pressure value of the regulating valve (7); in a case where the pressure value of the oil inlet end (A) of the hydraulic motor is greater than the opening set pressure value, open the regulating valve (7) to reduce the pressure value of the oil inlet end (A) of the hydraulic motor.

7. The control method of a closed motor hydraulic circuit according to claim 6, wherein, The step of, in a case where the pressure value of the oil inlet end (A) of the hydraulic motor is greater than the opening set pressure value, opening the regulating valve (7) to reduce the pressure value of the oil inlet end (A) of the hydraulic motor includes: determine a pressure difference between the pressure value of the oil inlet end (A) of the hydraulic motor and the opening set pressure value; determine a second opening degree control signal of the regulating valve (7) according to the pressure difference, wherein the second opening degree control signal is used to adjust the opening degree of the regulating valve (7) to adjust the pressure of the oil inlet end (A) of the hydraulic motor.

8. The control method of a closed motor hydraulic circuit according to claim 1 or 6 or 7, wherein, The closed motor hydraulic circuit further includes a rotating speed sensor for detecting an actual rotating speed of the hydraulic motor (4), and the step of, in a case where the speed value corresponding to the speed control instruction is greater than a preset speed, adjusting the rotating speed of the hydraulic motor (4) and limiting the pressure of the oil inlet end (A) of the hydraulic motor by controlling the regulating valve (7) includes the following steps: in a case where the speed value corresponding to the speed control instruction is greater than the preset speed, acquire the actual rotating speed of the hydraulic motor (4); adjust the output flow of the hydraulic pump (1) according to the actual rotating speed and the speed control instruction.

9. A closed motor hydraulic circuit wherein, comprise: a hydraulic motor (4); a hydraulic pump (1) for driving the hydraulic motor (4) to rotate; a motor bypass oil path connecting the oil inlet end (A) of the hydraulic motor and the oil outlet end (B) of the hydraulic motor and provided with a regulating valve (7) for controlling the flow of the motor bypass oil path; and a controller configured to perform the control method of the closed motor hydraulic circuit according to any one of claims 1 to 8.

10. A work machine, wherein, comprise the closed motor hydraulic circuit according to claim 9. comprise the closed motor hydraulic circuit according to claim 9.

Images