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

Abstract

The invention belongs to the technical field of hydraulic pressure, and particularly relates to a closed motor hydraulic circuit, a control method of the closed motor hydraulic circuit and an operation machine. The motor bypass oil way is connected with the oil inlet end of the hydraulic motor and the oil outlet end of the hydraulic motor and provided with an adjusting valve used for controlling the flow of the motor bypass oil way. The control method of the closed type motor hydraulic circuit comprises the following steps that a speed control instruction of the hydraulic motor is obtained; under the condition that the speed value corresponding to the speed control instruction is larger than the preset speed, the rotating speed of the hydraulic motor is adjusted, and the pressure of the oil inlet end of the hydraulic motor is limited by controlling an adjusting valve; and under the condition that the speed value corresponding to the speed control instruction is smaller than or equal to the preset speed, the rotating speed of the hydraulic motor is adjusted. By means of the control method of the closed type motor hydraulic circuit, the rotating speed of the hydraulic motor and the pressure of the oil inlet end of the hydraulic motor can be accurately and stably adjusted.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic technology, and in particular relates to a closed motor hydraulic circuit and a control method thereof, and an operating machine. Background Art

[0002] With the development of operating machinery technology, millimeter / second-level low-speed fine-tuning is required during the precise positioning of large load hoisting. The pump-controlled motor system in the prior art mainly controls the speed of the hydraulic motor based on the speed control instruction, collects the speed of the hydraulic motor in real time, and adjusts the output displacement of the hydraulic pump based on the speed of the hydraulic motor to adjust the speed of the hydraulic motor in real time. However, the speed of the hydraulic motor is affected to varying degrees by different factors under different working conditions, resulting in poor control accuracy of the hydraulic motor speed. Summary of the invention

[0003] The object of the present invention is to provide a closed motor hydraulic circuit and a control method thereof, and an operating machine, so as to accurately and stably adjust the rotation speed of a hydraulic motor and the pressure at the oil inlet end of the hydraulic motor.

[0004] In order to achieve the above objectives, the present invention provides a control method for a closed motor hydraulic circuit.

[0005] In some embodiments, the closed motor hydraulic circuit includes a hydraulic motor, a hydraulic pump and a motor bypass oil circuit, the motor bypass oil circuit connects the oil inlet end of the hydraulic motor and the oil outlet end of the hydraulic motor and is provided with a regulating valve for controlling the flow of the motor bypass oil circuit, and the control method of the closed motor hydraulic circuit includes the following steps:

[0006] Obtain speed control instructions for hydraulic motors;

[0007] When the speed value corresponding to the speed control instruction 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;

[0008] When 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.

[0009] 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 speed of the hydraulic motor includes: when 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 an output flow rate of the hydraulic pump according to the first flow rate, so as to adjust the speed of the hydraulic motor by adjusting the output flow rate of the hydraulic pump.

[0010] In some embodiments, determining the output flow of the hydraulic pump based on the first flow includes: determining the second flow based on the speed control instruction and the first preset correspondence, the second flow is the bypass overflow of the regulating valve, and the first preset correspondence is the correspondence between the speed control instruction and the second flow; determining the output flow of the hydraulic pump based on the second flow and the first flow.

[0011] In some embodiments, the output flow of the hydraulic pump is determined based on the second flow and the first flow, including: determining a third flow based on the pressure value at the oil inlet end of the hydraulic motor, the third flow being the leakage of the hydraulic motor; and determining the output flow of the hydraulic pump based on the first flow, the second flow, and the third flow.

[0012] In some embodiments, the closed motor hydraulic circuit also includes a speed sensor for detecting the actual speed of the hydraulic motor. When the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the step of adjusting the speed of the hydraulic motor also includes the following steps: when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, obtaining the actual speed of the hydraulic motor; determining a first opening control signal of the regulating valve according to the actual speed and the speed control instruction, the first opening control signal being used to adjust the opening of the regulating valve to adjust the speed of the hydraulic motor.

[0013] In some embodiments, when 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 regulating valve, including the following steps: obtaining the pressure value of the oil inlet end of the hydraulic motor and the pressure value of the oil outlet end of the hydraulic motor in real time; determining the opening set pressure value of the regulating valve according to the speed value corresponding to the speed control instruction, the pressure value of the oil outlet end of the hydraulic motor and a second preset corresponding relationship, wherein the second preset corresponding relationship is the corresponding relationship between the speed value corresponding to the speed control instruction, the pressure value of the oil outlet end of the hydraulic motor and the opening set pressure value of the regulating valve; when the pressure value at the oil inlet end of the hydraulic motor is greater than the opening set pressure value, opening the regulating valve to reduce the pressure value at the oil inlet end of the hydraulic motor.

[0014] In some embodiments, when the pressure value at the oil inlet end of the hydraulic motor is greater than the opening set pressure value, the step of opening the regulating valve to reduce the pressure value at the oil inlet end of the hydraulic motor includes: determining the pressure difference between the pressure value at the oil inlet end of the hydraulic motor and the opening set pressure value; determining a second opening control signal of the regulating valve according to the pressure difference, the second opening control signal being used to adjust the opening of the regulating valve to adjust the pressure at the oil inlet end of the hydraulic motor.

[0015] In some embodiments, the closed motor hydraulic circuit also includes a speed sensor for detecting the actual speed of the hydraulic motor. When the speed value corresponding to the speed control instruction 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 following steps are also included: when the speed value corresponding to the speed control instruction 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 instruction.

[0016] A second aspect of the present invention provides a closed motor hydraulic circuit, comprising:

[0017] Hydraulic motor;

[0018] A hydraulic pump, used to drive the hydraulic motor to rotate;

[0019] A motor bypass oil circuit, connecting the oil inlet end of the hydraulic motor and the oil outlet end of the hydraulic motor and provided with a regulating valve for controlling the flow of the motor bypass oil circuit;

[0020] and a controller configured to execute the above-mentioned control method of the closed motor hydraulic circuit.

[0021] A third aspect of the present invention provides a working machine comprising the above-mentioned closed motor hydraulic circuit.

[0022] In the above technical scheme, the present application provides a control method for a closed motor hydraulic circuit. When a 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. When the speed value corresponding to the speed control instruction 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 of the motor bypass oil circuit. By adopting the above 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; when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the speed of the hydraulic motor is adjusted to enable the hydraulic motor to rotate accurately at a low speed. In other words, by adopting the above method, different hydraulic control strategies can be performed on the hydraulic motor according to the speed working condition of the hydraulic motor, which helps the hydraulic motor to better cope with the influence of external factors under the working conditions, thereby achieving precise speed control.

[0023] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative work. In the accompanying drawings:

[0025] Figure 1 A flow chart of a method for controlling a closed motor hydraulic circuit according to an embodiment of the present invention;

[0026] Figure 2 A hydraulic principle diagram of a closed motor hydraulic circuit provided according to an embodiment of the present invention;

[0027] Figure 3 A control flow chart of a low-speed working mode of a hydraulic motor provided according to an embodiment of the present invention;

[0028] Figure 4 A control flow chart of a low-speed working mode of a hydraulic motor provided according to a specific embodiment of the present invention;

[0029] Figure 5 A flow chart of speed control of a hydraulic motor in a high-speed working mode according to an embodiment of the present invention;

[0030] Figure 6 A flow chart of pressure control at the oil inlet end of a hydraulic motor in a high-speed working mode according to an embodiment of the present invention;

[0031] Figure 7 The flowchart is a flow chart of pressure control and speed control at the oil inlet end of a hydraulic motor in a high-speed working mode according to a specific embodiment of the present invention.

[0032] Description of Reference Numerals

[0033] 1 Hydraulic pump 5 Relief valve

[0034] 2.1 First overflow oil supply valve 6 Hydraulic oil tank

[0035] 2.2 Second overflow oil supply valve 7 regulating valve

[0036] 3 Charge pump A Hydraulic motor oil inlet end

[0037] 4 Hydraulic motor B Hydraulic motor oil outlet DETAILED DESCRIPTION

[0038] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0039] The following describes a control method for a closed motor hydraulic circuit, a closed motor hydraulic circuit, and a working machine according to the present invention with reference to the accompanying drawings. Figure 1 As shown, it is a flow chart of a control method of a closed motor hydraulic circuit provided according to an embodiment of the present invention; Figure 2 , which is a hydraulic principle diagram of a closed motor hydraulic circuit provided according to an embodiment of the present invention. The closed motor hydraulic circuit comprises a hydraulic motor 4, a hydraulic pump 1 and a motor bypass oil circuit, wherein the motor bypass oil circuit connects an oil inlet port A of the hydraulic motor and an oil outlet port B of the hydraulic motor and is provided with a regulating valve 7 for controlling the flow of the motor bypass oil circuit, and a control method of the closed motor hydraulic circuit comprises the following steps:

[0040] S102, obtaining a speed control instruction of the hydraulic motor 4.

[0041] S104, when the speed value corresponding to the speed control instruction is greater than the preset speed, the rotation speed of the hydraulic motor 4 is adjusted, and the pressure of the oil inlet port A of the hydraulic motor is limited by controlling the regulating valve 7.

[0042] S106: When 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 4 is adjusted.

[0043] A closed motor hydraulic circuit is a closed hydraulic circuit including a hydraulic motor 4, in which the hydraulic oil in the closed hydraulic circuit continuously flows in the circuit to form a closed circuit. 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 invention includes a motor bypass oil circuit, which connects the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor. A regulating valve 7 for controlling the flow of the motor bypass oil circuit is provided on the motor bypass oil circuit. By adjusting the valve opening of the regulating valve 7, the flow of the motor bypass oil circuit can be adjusted, which can affect the pressure and flow of the hydraulic oil introduced into the hydraulic motor 4, thereby adjusting the rotation speed of the hydraulic motor 4 and the pressure of the oil inlet of the hydraulic motor 4.

[0044] Specifically, when the present invention adjusts the closed motor hydraulic circuit, the closed motor hydraulic circuit can be controlled by a controller (not shown in the figure). First, the controller can obtain the speed control instruction for the hydraulic motor 4. When 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 the high-speed working mode. When 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 the low-speed working mode. When the hydraulic motor 4 is in the high-speed working mode, the controller can adjust the speed of the hydraulic motor 4 to prevent the hydraulic motor 4 from having a large speed deviation. In addition, during the high-speed rotation of the hydraulic motor 4, the oil inlet pressure of the hydraulic motor 4 may increase suddenly. The controller can control the regulating valve 7 to open to reduce the pressure of the oil inlet end A of the hydraulic motor to protect the hydraulic components in the closed motor hydraulic circuit. When the hydraulic motor 4 is in the low-speed working mode, the controller can control the rotation speed of the hydraulic motor 4 to make the hydraulic motor 4 rotate accurately.

[0045] By adopting the control method of the closed motor hydraulic circuit mentioned above, when the hydraulic motor 4 is in the high-speed working mode, the controller can adjust the pressure of the oil inlet end A of the hydraulic motor when the hydraulic motor 4 rotates at high speed, and can control the speed of the hydraulic motor 4; when the hydraulic motor 4 is in the low-speed working mode, the controller can accurately adjust the speed of the hydraulic motor 4 to enable the hydraulic motor 4 to work smoothly.

[0046] In the first embodiment, when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the step of adjusting the speed of the hydraulic motor 4 includes: when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, determining the 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 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 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 to adjust the 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 issued by the controller. Among them, the hydraulic pump 1 can be selected as a variable pump or a fixed displacement pump driven by a variable speed motor.

[0047] In a specific embodiment, the output flow of the hydraulic pump 1 is proportional to the rotation speed of the hydraulic motor 4. By determining the proportionality coefficient between the rotation speed of the hydraulic motor 4 and the output flow of the hydraulic pump 1, the output flow of the hydraulic pump 1 can be accurately adjusted. For example, the hydraulic pump 1 is a variable pump. After determining the output flow of the hydraulic pump 1, the controller outputs a control signal to the variable pump to adjust the variable mechanism of the variable pump. The variable mechanism changes the swing angle so that the variable pump can output hydraulic oil of a corresponding flow according to the control signal.

[0048] 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 corresponding relationship, the second flow is the bypass overflow of the regulating valve 7, and the first preset corresponding relationship is the 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. The regulating valve 7 is a hydraulic valve that can adjust the valve opening of the regulating valve 7 according to the received control signal, thereby realizing precise adjustment of the flow ratio of the hydraulic oil. The regulating valve 7 is connected to the oil inlet port A of the hydraulic motor and the oil outlet port 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 path, and part of the hydraulic oil flowing into the regulating valve 7 will overflow from the regulating valve 7. Therefore, when adjusting the speed of the hydraulic motor 4 by the hydraulic pump 1, the hydraulic oil overflowing from the position of the regulating valve 7 should be considered. There is a first preset correspondence between the hydraulic flow overflowing at the regulating valve 7 and the speed value corresponding to the speed control instruction, and the controller can determine the second flow according to the first preset correspondence and the speed control instruction, wherein the second flow is the bypass overflow 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. Among them, the first preset correspondence can be a formula, a table or other. Compared with the required flow of the hydraulic motor 4 determined by the first embodiment, the second embodiment takes into account the hydraulic oil overflowing from the regulating valve 7, and can more accurately adjust the speed of the hydraulic motor 4.

[0049] 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 magnitude of the current input to the electric proportional regulating valve. It has a simple structure, precise adjustment, and fast response speed.

[0050] In another specific embodiment, the regulating valve 7 is an electrically controlled regulating valve, which can adjust the throttling area according to a control signal input to the electrically controlled regulating valve.

[0051] In addition, the regulating valve 7 may also be an adjustable relief valve, which can change the relief value according to the magnitude of the current input to the adjustable relief valve, thereby adjusting the pressure and flow of the hydraulic motor 4.

[0052] 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 port A of the hydraulic motor, the third flow rate is the leakage 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 amount of leakage at the hydraulic motor 4. Therefore, when adjusting the speed of the hydraulic motor 4 by the output flow rate of the hydraulic pump 1, the leakage of the hydraulic oil at the hydraulic motor 4 should be considered. The leakage of the hydraulic motor 4 is related to the pressure of the oil inlet port A of the hydraulic motor. Therefore, according to the pressure of the oil inlet port A of the hydraulic motor, the leakage 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 port A of the hydraulic motor, and the third flow rate is the leakage 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 of the hydraulic pump 1 is determined based on the leakage of the hydraulic motor 4, the required flow of the hydraulic motor 4, and the overflow of the regulating valve 7. Compared with the output flow of the hydraulic pump 1 determined in the second embodiment, it is more accurate, so that the controller can adjust the rotation speed of the hydraulic motor 4 more accurately.

[0053] In a specific embodiment, the controller can determine the output flow of the hydraulic pump 1 according to formula (1):

[0054] V=k 2 P in +k 3 ω+k 4 ω (1)

[0055] Where V is the output flow of hydraulic pump 1, k 2 is the equivalent leakage coefficient of hydraulic motor 4, k 3 is the equivalent displacement coefficient of the hydraulic motor 4, k 4 is the bypass damping coefficient of the regulating valve 7, P in is the pressure value of the oil inlet port A of the hydraulic motor, ω is the speed value corresponding to the speed control command, k 3 ω is the first flow rate, k 4 ω is the second flow rate, k 2 P in The third flow rate.

[0056] In the fourth embodiment, the closed motor hydraulic circuit further includes a speed sensor (not shown in the figure) for detecting the actual 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, the step of adjusting the speed of the hydraulic motor 4 also includes the following steps: when the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the actual speed of the hydraulic motor 4 is obtained; according to the actual speed and the speed control instruction, the first opening control signal of the regulating valve 7 is determined, and the first opening control signal is used to adjust the opening of the regulating valve 7 to adjust the speed of the hydraulic motor 4. The speed sensor can be used to determine the 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, the controller can obtain the actual speed of the hydraulic motor 4 and compare the actual speed with the speed corresponding to the speed control instruction. The controller can adjust the speed according to the difference between the actual speed and the speed corresponding to the speed control instruction. A regulating valve 7 for adjusting the flow of the motor bypass oil circuit is provided on the motor bypass oil circuit. When the flow of the motor bypass oil circuit changes, the flow and pressure of the hydraulic oil flowing into the hydraulic motor 4 will also change, thereby adjusting the speed of the hydraulic motor 4. The speed sensor can detect the actual speed of the hydraulic motor 4 . When there is a difference between the actual speed and the speed value corresponding to the speed control instruction, the controller can control the regulating valve 7 to adjust the flow of the hydraulic motor 4 , thereby adjusting the speed of the hydraulic motor 4 .

[0057] In one embodiment, the regulating valve 7 is an electric proportional regulating valve, which can adjust the speed of the hydraulic motor 4 according to the opening of the first regulating regulating valve 7. The controller determines the first regulating current of the electric proportional regulating valve according to the inlet and outlet pressure difference of the hydraulic motor 4, the speed control instruction and the preset third corresponding relationship, and transmits the first regulating current to the electric proportional regulating valve. Among them, the preset third corresponding relationship can be a formula, a table or other. After the electric proportional regulating valve is opened according to the first regulating current, the speed sensor obtains the actual speed of the hydraulic motor 4 and transmits the detection value to the controller. The controller compares the actual speed with the speed value corresponding to the speed control instruction, and performs PID adjustment on the first regulating current of the electric proportional regulating valve, so that the actual speed of the hydraulic motor 4 is adjusted to the speed corresponding to the speed control instruction.

[0058] In a specific embodiment, the first regulating current of the electric proportional regulating valve can be determined according to the following formula (2):

[0059]

[0060] Among them, I 1 is the first regulating current, k 4 is the bypass damping coefficient of the electric proportional control valve, k 5is the current-displacement coefficient of the electric proportional control valve, ω is the speed value corresponding to the speed control command, C d is the flow coefficient, ρ is the density of hydraulic oil, P in is the pressure value of the oil inlet port A of the hydraulic motor, P out It is the pressure value at the oil outlet port B of the hydraulic motor.

[0061] In one embodiment, Figure 3 As shown, it is a control flow chart of the low-speed working mode of the hydraulic motor 4 provided according to an embodiment of the present invention. Step S103 includes the following detailed steps: S202, real-time acquisition of the pressure of the oil inlet port A of the hydraulic motor and the oil outlet port B of the hydraulic motor. S204, determining the required flow rate 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 rate so that the hydraulic motor 4 rotates according to the speed value corresponding to the required speed control instruction. S208, according to the pressure of the oil inlet port A of the hydraulic motor, the pressure of the oil outlet port B of the hydraulic motor and the speed value corresponding to the speed control instruction, determine the first regulating current of the electric proportional regulating valve. S210, according to the first regulating current, control the electric proportional regulating valve to open and adjust the speed of the hydraulic motor 4. S212, compare the actual speed of the hydraulic motor 4 with the speed corresponding to the speed control instruction, and adjust the regulating current of the electric proportional regulating valve according to the comparison result, so that the hydraulic motor 4 rotates accurately according to the speed corresponding to the speed control instruction.

[0062] In a specific embodiment, Figure 4 As shown, it is a control flow chart of the low-speed working mode of the hydraulic motor 4 provided according to a specific embodiment of the present invention. 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 obtain the speed command of the hydraulic motor 4 and the hydraulic oil pressure of the oil ports at both ends of the hydraulic motor 4, and compare the pressure of the oil ports at both ends to determine the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor, determine the output flow of the variable pump according to the above formula (1), and adjust the swing angle γ of the variable pump. According to the above formula (2), the regulating current of the electric proportional reversing valve is determined, and the regulating current of the electric proportional reversing valve is adjusted. The actual speed of the hydraulic motor 4 is obtained, and the regulating current of the electric proportional reversing valve is PID-regulated according to the difference between the speed control command and the actual speed. Among them, the electric proportional reversing valve can adjust the valve opening or perform reversing operation according to the electric proportion.

[0063] 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 port A of the hydraulic motor is limited by controlling the regulating valve 7, including the following steps: obtaining the pressure value of the oil inlet port A of the hydraulic motor and the pressure value of the oil outlet port B of the hydraulic motor in real time; determining the opening setting pressure value of the regulating valve 7 according to the speed value corresponding to the speed control instruction, the pressure value of the oil outlet port B of the hydraulic motor and the second preset corresponding relationship, wherein the second preset corresponding relationship is the corresponding relationship between the speed value corresponding to the speed control instruction, the pressure value of the oil outlet port B of the hydraulic motor and the opening setting pressure value of the regulating valve 7; when the pressure value of the oil inlet port A of the hydraulic motor is greater than the opening setting pressure value, the regulating valve 7 is opened to reduce the pressure value of the oil inlet port A of the hydraulic motor. 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 port A of the hydraulic motor may be large during the starting and braking process, thereby causing the closed motor hydraulic circuit to be damaged by force. Therefore, in the high-speed working mode of the hydraulic motor 4, when the pressure at the oil inlet port A of the hydraulic motor is greater than the opening set pressure value, the regulating valve 7 can be opened to reduce the pressure at the oil inlet port A of the hydraulic motor.

[0064] 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 port A of the hydraulic motor and the oil outlet port B of the hydraulic motor in real time, and determines the opening set pressure value that needs to be adjusted for the pressure of the oil outlet port B of the hydraulic motor according to the speed value corresponding to the speed control instruction, the pressure value of the oil outlet port B of the hydraulic motor and the second preset corresponding relationship. Among them, the second preset corresponding relationship is a formula, a table or other. When the pressure value of the oil inlet port A of the hydraulic motor is greater than the opening set pressure value, the controller can open the regulating valve 7 to divert the hydraulic oil in the closed motor hydraulic circuit, reduce the pressure of the oil inlet port A of the hydraulic motor, and protect the hydraulic components in the closed motor hydraulic circuit.

[0065] In a specific embodiment, the opening set pressure value can be obtained according to the following formula (3):

[0066]

[0067] Among them, P set is the opening set pressure value, k 1 is the pressure shock coefficient, J m The equivalent moment of 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 mis the displacement of hydraulic motor 4, P out is the pressure value of the hydraulic motor's oil outlet port B. The response time requirement of the controller is related to the controller's own acquisition frequency or acquisition time interval.

[0068] In one embodiment, when the pressure value of the oil inlet port 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 port A of the hydraulic motor includes: determining the pressure difference between the pressure value of the oil inlet port A of the hydraulic motor and the opening set pressure value; determining the second opening control signal of the regulating valve 7 according to the pressure difference, and the second opening control signal is used to adjust the opening of the regulating valve 7 to adjust the pressure of the oil inlet port A of the hydraulic motor. The motor bypass oil circuit can divert the hydraulic oil flowing into the hydraulic motor 4, and the larger the diverted flow rate, the smaller the pressure of the oil inlet port A of the hydraulic motor. The second opening control signal can control the regulating valve 7 to open the valve port according to the valve port opening corresponding to the second opening control signal. When it is necessary to open the regulating valve 7 to reduce the pressure of the oil inlet port A of the hydraulic motor, the controller can determine the valve port opening of the regulating valve 7 according to the pressure difference between the pressure value of the oil inlet port A of the hydraulic motor and the opening set pressure, and send the second opening control signal to the regulating valve 7. Among them, the second opening control signal is the second regulating current, and the larger the current value of the second regulating current is, the larger the valve opening of the regulating valve 7 is. By adopting the above-mentioned control method of the closed motor hydraulic circuit, when the pressure value of the oil inlet port A of the hydraulic motor is greater than the opening setting pressure, the pressure of the oil inlet port A of the hydraulic motor can be adjusted according to the difference between the opening setting pressure and the pressure value of the oil inlet port A of the hydraulic motor. Under the condition of ensuring that the hydraulic oil pressure is within a safe range, the hydraulic oil is diverted to a minimum extent to prevent the pressure reduction from causing the hydraulic motor 4 to rotate too slowly, thereby affecting the working efficiency.

[0069] In a specific embodiment, the second opening control signal is a second regulating current, and the current value of the current signal is obtained according to the following formula (4):

[0070] I 2 =k 2 (P in -P set ) +I de (4)

[0071] Among them, I 2 is the second regulating current, k 2 is the equivalent leakage coefficient of the hydraulic motor 4, P in is the pressure value of the oil inlet port A of the hydraulic motor, P set To open the set pressure value, I de is the preset current coefficient.

[0072] In a specific embodiment, the controller adjusts the pressure of the oil inlet port A of the hydraulic motor only when the hydraulic motor 4 is started or stopped, so as to avoid excessive impact when the hydraulic motor 4 is started or stopped.

[0073] In one embodiment, the closed motor hydraulic circuit also includes a speed sensor for detecting the actual speed of the hydraulic motor 4. 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 port A of the hydraulic motor is limited by controlling the regulating valve 7. The following steps are also included: when the speed value corresponding to the speed control instruction is greater than the preset speed, the actual speed of the hydraulic motor 4 is obtained; and the output flow of the hydraulic pump 1 is adjusted according to the actual speed and the speed control instruction. When the hydraulic motor 4 is in the high-speed working mode, the actual 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 speed detected by the speed sensor, and 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 speed of the hydraulic motor 4. The control method of the closed motor hydraulic circuit described above can be used to adjust the speed of the high-speed rotating hydraulic motor 4 to prevent the hydraulic motor 4 from deviating from the speed corresponding to the speed control instruction and affecting the working effect.

[0074] In one embodiment, the controller can perform PID adjustment on the output flow of the hydraulic pump 1 according to the actual speed and the speed corresponding to the speed control instruction, so that the hydraulic pump 1 outputs the corresponding hydraulic oil so that the speed of the hydraulic motor 4 gradually approaches the speed value corresponding to the speed control instruction.

[0075] In one embodiment, the hydraulic pump 1 is a variable displacement pump, such as Figure 5 As shown, it is a flow chart of speed control of the hydraulic motor 4 in the high-speed working mode provided according to an embodiment of the present invention. Step S102 includes the following detailed steps: S302, real-time acquisition of the pressure of the oil inlet port A of the hydraulic motor and the oil outlet port B of the hydraulic motor. S304, determining the required flow rate of the variable pump according to the speed value corresponding to the speed control instruction. S306, controlling the variable pump to adjust the swing angle of the variable pump according to the required flow rate. S308, after the hydraulic motor 4 starts to rotate, the swing angle of the hydraulic pump 1 is adjusted according to the actual speed of the hydraulic motor 4 and the speed value corresponding to the speed control instruction, so as to adjust the speed of the hydraulic motor 4.

[0076] In addition, if Figure 6As shown, it is a pressure control flow chart of the oil inlet end of the hydraulic motor 4 provided in the high-speed working mode according to an embodiment of the present invention. The regulating valve 7 is an electric proportional regulating valve, and step S102 also includes the following detailed steps: S402, determining the opening setting pressure of the electric proportional regulating valve according to the speed value corresponding to the speed control instruction and the oil outlet pressure value of the hydraulic motor 4. S404, when the pressure at the oil inlet end A of the hydraulic motor is greater than the opening setting pressure, controlling the electric proportional regulating valve to determine the second regulating 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, adjusting the valve opening of the electric proportional regulating valve according to the second regulating current to reduce the pressure at the oil inlet end A of the hydraulic motor.

[0077] In a specific embodiment, Figure 7 As shown, it is 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 a specific embodiment of the present invention. The regulating valve 7 is an electric proportional reversing 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 command of the hydraulic motor 4, the acquisition time interval t of the controller, and the hydraulic oil pressure of the oil ports at both ends of the hydraulic motor 4, and compare the pressure of the oil ports at both ends to determine the oil inlet end A of the hydraulic motor and the oil outlet end B of the hydraulic motor, and determine the opening set pressure value of the electric proportional reversing valve according to the above formula (3). When the hydraulic oil pressure at 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 reversing valve is determined according to the above formula (4), and the current of the electric proportional reversing valve is adjusted according to the second regulating current. When the hydraulic oil pressure at the oil inlet end A of the hydraulic motor is less than or equal to the opening set pressure value, the electric proportional reversing valve is closed. Moreover, in the embodiment of the present invention, the speed of the hydraulic motor 4 can be determined in real time by a motor speed sensor, and the swing angle of the variable pump can be PID adjusted by comparing the speed of the hydraulic motor 4 with the motor speed command to accurately adjust the speed of the hydraulic motor 4.

[0078] The speed of the hydraulic motor 4 is adjusted by adjusting the flow of the hydraulic pump 1. In addition, when the pressure at the oil inlet port 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 at the oil inlet port A of the hydraulic motor to prevent the closed motor hydraulic circuit components from being damaged due to excessive pressure.

[0079] In one embodiment, the closed motor hydraulic circuit further includes an oil replenishment circuit, which can replenish the hydraulic oil overflowing from the hydraulic motor 4, the hydraulic pump 1 and the regulating valve 7 to prevent cavities in the hydraulic pump and the hydraulic motor.

[0080] In one embodiment, the oil replenishment circuit includes an oil replenishment pump 3 and multiple overflow oil replenishment valves. The oil replenishment pump 3 is connected to the hydraulic oil tank 6 and is used to transport the hydraulic oil to the overflow oil replenishment valves. The overflow oil replenishment valves can transport the hydraulic oil from the oil replenishment circuit to the hydraulic pump 1, the hydraulic motor 4 or the regulating valve 7 in a unidirectional manner.

[0081] In a specific embodiment, the oil replenishment circuit includes a first overflow oil replenishment valve 2.1 and a second overflow oil replenishment valve 2.2, and the first overflow oil replenishment valve 2.1 and the second overflow oil replenishment valve 2.2 replenish oil to the oil ports at both ends of the hydraulic pump 1 respectively.

[0082] In one embodiment, the oil replenishment pump 3 is coupled to the hydraulic pump 1 , and the rotation of the hydraulic pump 1 can drive the oil replenishment pump 3 to work, which has high working efficiency, simple structure, and is easy to implement.

[0083] In one embodiment, the oil replenishment circuit also includes a relief valve 5, one end of the relief valve 5 is connected to the oil outlet end of the oil replenishment pump 3, and the other end of the relief valve 5 is connected to the hydraulic oil tank 6. The relief valve 5 is used to prevent the hydraulic oil pressure in the oil replenishment circuit from being too high, causing damage to the hydraulic components in the closed motor hydraulic circuit.

[0084] The embodiment of the present application also provides a closed motor hydraulic circuit, comprising:

[0085] Hydraulic motor 4;

[0086] A hydraulic pump 1, used to drive a hydraulic motor 4 to rotate;

[0087] A motor bypass oil circuit, connecting the oil inlet port A of the hydraulic motor and the oil outlet port B of the hydraulic motor and provided with a regulating valve 7 for controlling the flow of the motor bypass oil circuit;

[0088] and a controller configured to execute the above-mentioned control method of the closed motor hydraulic circuit.

[0089] In one embodiment, a working machine is provided, comprising the above-mentioned closed motor hydraulic circuit.

[0090] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0091] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0093] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A control method for a closed motor hydraulic circuit, characterized in that: The closed motor hydraulic circuit comprises a hydraulic motor (4), a hydraulic pump (1) and a motor bypass oil circuit, wherein the motor bypass oil circuit connects an oil inlet end (A) of the hydraulic motor and an oil outlet end (B) of the hydraulic motor and is provided with a regulating valve (7) for controlling the flow of the motor bypass oil circuit, and the control method comprises the following steps: Obtaining a speed control instruction of the hydraulic motor (4); When the speed value corresponding to the speed control instruction is greater than a preset speed, the rotation speed of the hydraulic motor (4) is adjusted, and the pressure at the oil inlet end (A) of the hydraulic motor is limited by controlling the regulating valve (7); When 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 (4) is adjusted.

2. The control method of a closed motor hydraulic circuit according to claim 1, characterized in that: When the speed value corresponding to the speed control instruction is less than or equal to the preset speed, the step of adjusting the speed of the hydraulic motor (4) comprises: In a case where 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; The output flow rate of the hydraulic pump (1) is determined according to the first flow rate, so as to adjust the rotation speed of the hydraulic motor (4) by adjusting the output flow rate of the hydraulic pump (1).

3. The control method of the closed motor hydraulic circuit according to claim 2, characterized in that: Determining the output flow of the hydraulic pump (1) according to the first flow comprises: determining a second flow rate according to the speed control instruction and a first preset corresponding relationship, the second flow rate being a bypass overflow of the regulating valve (7), and the first preset corresponding relationship being a corresponding relationship between the speed control instruction and the second flow rate; The output flow rate of the hydraulic pump (1) is determined according to the second flow rate and the first flow rate.

4. The control method of the closed motor hydraulic circuit according to claim 3, characterized in that: Determining the output flow rate of the hydraulic pump (1) according to the second flow rate and the first flow rate comprises: determining a third flow rate according to a pressure value at an oil inlet end (A) of the hydraulic motor, wherein the third flow rate is a leakage amount of the hydraulic motor (4); The output flow rate of the hydraulic pump (1) is determined according to the first flow rate, the second flow rate, and the third flow rate.

5. The control method of a closed motor hydraulic circuit according to any one of claims 1 to 4, characterized in that: The closed motor hydraulic circuit further comprises a speed sensor for detecting the actual speed of the hydraulic motor (4), and the step of adjusting the 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: When the speed value corresponding to the speed control instruction is less than or equal to the preset speed, obtaining the actual speed of the hydraulic motor (4); A first opening control signal of the regulating valve (7) is determined according to the actual rotational speed and the speed control instruction, wherein the first opening control signal is used to adjust the opening of the regulating valve (7) to adjust the rotational speed of the hydraulic motor (4).

6. The control method of a closed motor hydraulic circuit according to claim 1, characterized in that: When the speed value corresponding to the speed control instruction is greater than a preset speed, the speed of the hydraulic motor (4) is adjusted, and the pressure at the oil inlet end (A) of the hydraulic motor is limited by controlling the regulating valve (7), comprising the following steps: Real-time acquisition of the pressure value of the oil inlet end (A) of the hydraulic motor and the pressure value of the oil outlet end (B) of the hydraulic motor; Determining the opening set pressure value of the regulating valve (7) according to the speed value corresponding to the speed control instruction, the pressure value at 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 between the speed value corresponding to the speed control instruction, the pressure value at the oil outlet end (B) of the hydraulic motor and the opening set pressure value of the regulating valve (7); When the pressure value at the oil inlet end (A) of the hydraulic motor is greater than the opening set pressure value, the regulating valve (7) is opened to reduce the pressure value at the oil inlet end (A) of the hydraulic motor.

7. The control method of a closed motor hydraulic circuit according to claim 6, characterized in that: The step of opening the regulating valve (7) to reduce the pressure value at the oil inlet end (A) of the hydraulic motor when the pressure value at the oil inlet end (A) of the hydraulic motor is greater than the opening set pressure value comprises: Determine the pressure difference between the pressure value at the oil inlet end (A) of the hydraulic motor and the opening set pressure value; A second opening control signal of the regulating valve (7) is determined according to the pressure difference, and the second opening control signal is used to adjust the opening of the regulating valve (7) to adjust the pressure at the oil inlet end (A) of the hydraulic motor.

8. The control method of a closed motor hydraulic circuit according to claim 1, 6 or 7, characterized in that: The closed motor hydraulic circuit further comprises a speed sensor for detecting the actual speed of the hydraulic motor (4); when the speed value corresponding to the speed control instruction is greater than a preset speed, the speed of the hydraulic motor (4) is adjusted, and the pressure at the oil inlet end (A) of the hydraulic motor is limited by controlling the regulating valve (7); the method further comprises the following steps: When the speed value corresponding to the speed control instruction is greater than the preset speed, obtaining the actual speed of the hydraulic motor (4); The output flow of the hydraulic pump (1) is adjusted according to the actual rotation speed and the speed control instruction.

9. A closed motor hydraulic circuit, characterized in that: include: Hydraulic motor (4); A hydraulic pump (1), used for driving the hydraulic motor (4) to rotate; a motor bypass oil circuit, connecting an oil inlet end (A) of the hydraulic motor and an oil outlet end (B) of the hydraulic motor and provided with a regulating valve (7) for controlling the flow of the motor bypass oil circuit; and A controller is configured to execute the control method of the closed motor hydraulic circuit according to any one of claims 1 to 8.

10. A working machine, characterized in that: Comprising the closed motor hydraulic circuit according to claim 9.

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