Closed-loop motor hydraulic circuit and its control method, operating machinery

Abstract

This invention belongs to the field of hydraulic technology, specifically relating to a closed-loop motor hydraulic circuit and its control method, as well as a working machine. The closed-loop motor hydraulic circuit includes a hydraulic motor, a hydraulic pump, and a motor bypass oil circuit. The motor bypass oil circuit connects the inlet end and outlet end of the hydraulic motor and is equipped with a regulating valve for controlling the flow rate of the motor bypass oil circuit. The control method of the closed-loop motor hydraulic circuit includes the following steps: obtaining a speed control command for the hydraulic motor; adjusting the rotational speed of the hydraulic motor when the speed value corresponding to the speed control command is greater than a preset speed, and limiting the pressure at the inlet end of the hydraulic motor by controlling the regulating valve; adjusting the rotational speed of the hydraulic motor when the speed value corresponding to the speed control command is less than or equal to the preset speed. The above-described control method for the closed-loop motor hydraulic circuit enables precise and stable adjustment of the rotational speed and the pressure at the inlet end of the hydraulic motor.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic technology, specifically relating to a closed-loop motor hydraulic circuit and its control method, as well as a working machine. Background Technology

[0002] With the development of heavy-duty lifting machinery technology, precise positioning under heavy loads requires low-speed fine-tuning at the millimeter / second level. Current pump-controlled motor systems primarily control the hydraulic motor's speed based on speed control commands and collect real-time data on the hydraulic motor's speed. The output displacement of the hydraulic pump is then adjusted based on this speed to regulate the hydraulic motor's speed in real time. However, the hydraulic motor's speed is affected to varying degrees by different factors under different operating conditions, resulting in poor speed control accuracy. Summary of the Invention

[0003] The purpose of this invention is to provide a closed-loop hydraulic circuit for a motor and its control method, as well as a working machine, so as to accurately and stably regulate the speed of the hydraulic motor and the pressure at the oil inlet of the hydraulic motor.

[0004] To achieve the above objectives, the present invention provides a control method for a closed-loop motor hydraulic circuit.

[0005] In some embodiments, the closed-loop motor hydraulic circuit includes a hydraulic motor, a hydraulic pump, and a motor bypass oil passage. The motor bypass oil passage connects the inlet end of the hydraulic motor to the outlet end of the hydraulic motor and is equipped with a regulating valve for controlling the flow rate of the motor bypass oil passage. The control method of the closed-loop motor hydraulic circuit includes the following steps:

[0006] Obtain speed control commands from the hydraulic motor;

[0007] 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 of the hydraulic motor is limited by controlling the regulating valve.

[0008] When the speed value corresponding to the speed control command is less than or equal to the preset speed, the speed of the hydraulic motor is adjusted.

[0009] In some embodiments, when the speed value corresponding to the speed control command is less than or equal to a preset speed, the step of adjusting the rotational speed of the hydraulic motor includes: determining a first flow rate according to the speed control command when the speed value corresponding to the speed control command is less than or equal to the preset speed; determining the output flow rate of the hydraulic pump according to the first flow rate, so as to adjust the rotational speed of the hydraulic motor by adjusting the output flow rate of the hydraulic pump.

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

[0011] In some implementations, determining the output flow rate of the hydraulic pump based on the second flow rate and the first flow rate includes: determining a third flow rate based on the pressure value at the inlet end of the hydraulic motor, wherein the third flow rate is the leakage of the hydraulic motor; and determining the output flow rate of the hydraulic pump based on the first flow rate, the second flow rate, and the third flow rate.

[0012] 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 less than or equal to a preset speed, the step of adjusting the speed of the hydraulic motor further includes the following steps: when the speed value corresponding to the speed control command is less than or equal to the preset speed, acquiring the actual speed of the hydraulic motor; determining a first opening control signal for the regulating valve based on the actual speed and the speed control command, 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, adjusting the rotational speed of the hydraulic motor and limiting the pressure at the inlet of the hydraulic motor by controlling the regulating valve when the speed value corresponding to the speed control command is greater than the preset speed includes the following steps: acquiring the pressure value at the inlet of the hydraulic motor and the pressure value at the outlet 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 command, the pressure value at the outlet of the hydraulic motor, and a second preset correspondence, wherein the second preset correspondence is the correspondence between the speed value corresponding to the speed control command, the pressure value at the outlet of the hydraulic motor, and the opening set pressure value of the regulating valve; and opening the regulating valve to reduce the pressure value at the inlet of the hydraulic motor when the pressure value at the inlet of the hydraulic motor is greater than the opening set pressure value.

[0014] 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.

[0015] 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.

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

[0017] Hydraulic motor;

[0018] A hydraulic pump is used to drive a hydraulic motor to rotate.

[0019] 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.

[0020] And the controller is configured to execute the control method of the closed motor hydraulic circuit described above.

[0021] A third aspect of the present invention provides a working machine, including the aforementioned closed-loop motor hydraulic circuit.

[0022] In the above technical solution, this application provides a control method for a closed-loop hydraulic circuit of a motor. When a speed control command for the hydraulic motor is received, it is determined whether the speed value corresponding to the speed control command is greater than a preset speed. If the speed value corresponding to the speed control command is greater than the preset speed, the rotational speed of the hydraulic motor is adjusted, and the pressure at the inlet end of the hydraulic motor is limited by controlling the regulating valve of the motor bypass oil circuit. Using the above method, the speed of a 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 command is less than or equal to the preset speed, the rotational speed of the hydraulic motor is adjusted so that the hydraulic motor can rotate accurately at low speed. In other words, using the above method, different hydraulic control strategies can be applied to the hydraulic motor according to the operating conditions of the hydraulic motor, which helps the hydraulic motor to better cope with the influence of external factors under operating 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 section. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. Those skilled in the art can obtain other drawings based on the structures shown in these drawings without any inventive effort. In the drawings:

[0025] Figure 1 A flowchart of a control method for a closed-loop motor hydraulic circuit according to an embodiment of the present invention;

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

[0027] Figure 3 This is a control flowchart for the low-speed operating mode of a hydraulic motor according to an embodiment of the present invention;

[0028] Figure 4 This is a control flowchart for the low-speed operating mode of a hydraulic motor according to a specific embodiment of the present invention;

[0029] Figure 5 This is a flowchart illustrating the speed control of a hydraulic motor in high-speed operating mode according to an embodiment of the present invention.

[0030] Figure 6 A flowchart illustrating the pressure control at the oil inlet end of a hydraulic motor in high-speed operating mode according to an embodiment of the present invention.

[0031] Figure 7 This is a flowchart illustrating the pressure control and speed control at the oil inlet end of a hydraulic motor in high-speed operating mode, according to a specific embodiment of the present invention.

[0032] Explanation of reference numerals in the attached figures

[0033] 1. Hydraulic pump; 5. Relief valve

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

[0035] 2.2 Second overflow replenishment valve 7 regulating valve

[0036] 3. Oil pump A, oil inlet end of hydraulic motor.

[0037] 4. Hydraulic Motor B: Oil outlet end of the hydraulic motor. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0039] The control method, closed-loop motor hydraulic circuit, and working machinery according to the present invention are described below with reference to the accompanying drawings. Figure 1 The diagram shown is a flowchart of a control method for a closed-loop motor hydraulic circuit according to an embodiment of the present invention; as shown... Figure 2 The diagram shown is a hydraulic schematic of a closed-loop motor hydraulic circuit according to an embodiment of the present invention. The closed-loop motor hydraulic circuit includes a hydraulic motor 4, a hydraulic pump 1, and a motor bypass oil circuit. The motor bypass oil circuit connects the inlet end A of the hydraulic motor to the outlet end B of the hydraulic motor and is equipped with a regulating valve 7 for controlling the flow rate of the motor bypass oil circuit. The control method of the closed-loop motor hydraulic circuit includes the following steps:

[0040] S102, Obtain the speed control command for hydraulic motor 4.

[0041] S104, when the speed value corresponding to the speed control command is greater than the preset speed, adjust the speed of the hydraulic motor 4 and limit the pressure at the oil inlet A of the hydraulic motor by controlling the regulating valve 7.

[0042] S106, when the speed value corresponding to the speed control command is less than or equal to the preset speed, the rotational speed of the hydraulic motor 4 is adjusted.

[0043] The closed-loop motor hydraulic circuit is a closed hydraulic circuit that includes a hydraulic motor 4. Hydraulic oil flows continuously within the closed-loop circuit, forming a closed circuit. By recycling the hydraulic oil, the closed-loop hydraulic circuit improves system efficiency and energy utilization. The hydraulic motor 4 converts the hydraulic energy in the closed-loop motor hydraulic circuit into mechanical energy to drive external components to rotate or move. The closed-loop motor hydraulic circuit of this invention includes a motor bypass oil passage connecting the inlet A and outlet B of the hydraulic motor. A regulating valve 7 is installed on the motor bypass oil passage to control the flow rate. By adjusting the opening of the regulating valve 7, the flow rate of the motor bypass oil passage can be adjusted, affecting the hydraulic oil pressure and flow rate supplied to the hydraulic motor 4, thereby regulating the speed of the hydraulic motor 4 and the pressure at the inlet of the hydraulic motor 4.

[0044] Specifically, when adjusting the hydraulic circuit of a closed-loop motor, the present invention uses a controller (not shown in the figure) to control the hydraulic circuit. First, the controller receives a speed control command for the hydraulic motor 4. If the speed value corresponding to the speed control command is greater than a preset speed, the hydraulic motor 4 is determined to be in a high-speed operating mode; if the speed value corresponding to the speed control command is less than or equal to the preset speed, the hydraulic motor 4 is determined to be in a low-speed operating mode. In the high-speed operating mode, the controller adjusts the speed of the hydraulic motor 4 to prevent large speed deviations. Furthermore, during high-speed rotation of the hydraulic motor 4, the inlet pressure of the hydraulic motor 4 may suddenly increase. The controller can control the opening of the regulating valve 7 to reduce the pressure at the inlet A of the hydraulic motor, thus protecting the hydraulic components in the closed-loop motor hydraulic circuit. In the low-speed operating mode, the controller controls the rotational speed of the hydraulic motor 4 to ensure precise rotation.

[0045] Using the above-mentioned closed-loop hydraulic circuit control method, when the hydraulic motor 4 is in high-speed working mode, the controller can adjust the pressure at the oil inlet end A of the hydraulic motor when the hydraulic motor 4 is rotating at high speed, and can control the speed of the hydraulic motor 4; when the hydraulic motor 4 is in low-speed working mode, the controller can precisely adjust the speed of the hydraulic motor 4 so that the hydraulic motor 4 can work smoothly.

[0046] In the first embodiment, the step of adjusting the rotational speed of the hydraulic motor 4 when the speed value corresponding to the speed control command is less than or equal to the preset speed includes: determining a first flow rate according to the speed control command when the speed value corresponding to the speed control command is less than or equal to the preset speed; determining the output flow rate of the hydraulic pump 1 according to the first flow rate, so as to adjust the rotational speed of the hydraulic motor 4 by adjusting the output flow rate of the hydraulic pump 1. After obtaining the speed control command, the controller can determine the first flow rate according to the control command, wherein the first flow rate is the flow rate required for the rotational speed of the hydraulic motor 4 to reach the speed value corresponding to the speed control command. The controller can control the hydraulic pump 1 to output the corresponding flow rate to adjust the rotational speed of the hydraulic motor 4. The hydraulic pump 1 can adjust the hydraulic oil flow rate output by the hydraulic pump 1 according to the control command issued by the controller. The hydraulic pump 1 can be selected as a variable pump or a fixed displacement pump driven by a variable speed motor.

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

[0048] In the second embodiment, determining the output flow rate of hydraulic pump 1 based on the first flow rate includes: determining a second flow rate based on a speed control command and a first preset correspondence, where the second flow rate is the bypass overflow flow rate of regulating valve 7, and the first preset correspondence is the correspondence between the speed control command and the second flow rate; and determining the output flow rate of hydraulic pump 1 based on the second flow rate and the first flow rate. Regulating valve 7 is a hydraulic valve capable of adjusting its opening degree according to a received control signal, thereby achieving precise proportional regulation of the hydraulic oil flow rate. Regulating valve 7 is connected to the inlet port A and outlet port B of the hydraulic motor. When the hydraulic motor 4 is operating, some hydraulic oil flows into regulating valve 7 through the motor bypass oil passage. A portion of the hydraulic oil flowing into regulating valve 7 overflows from regulating valve 7. Therefore, when adjusting the speed of hydraulic motor 4 using hydraulic pump 1, the hydraulic oil overflowing from regulating valve 7 should be considered. A first preset correspondence exists between the hydraulic flow overflowing at regulating valve 7 and the speed value corresponding to the speed control command. The controller can determine a second flow rate based on the first preset correspondence and the speed control command, where the second flow rate is the bypass overflow of regulating valve 7. Therefore, the output flow rate of hydraulic pump 1 can be determined based on the first and second flow rates. The first preset correspondence can be a formula, table, or other method. Compared to the required flow rate of hydraulic motor 4 determined in the first embodiment, the second embodiment takes into account the hydraulic oil overflowing from regulating valve 7, enabling more precise adjustment of the rotational speed of hydraulic motor 4.

[0049] In one specific embodiment, the regulating valve 7 is an electro-proportional regulating valve. Compared with other forms of hydraulic regulating valves, the electro-proportional regulating valve can easily adjust the throttling area of ​​the valve body according to the magnitude of the current input to the electro-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 the control signal input to the electrically controlled regulating valve.

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

[0052] In the third embodiment, determining the output flow rate of hydraulic pump 1 based on the second and first flow rates includes: determining a third flow rate based on the pressure value at the inlet A of the hydraulic motor, where the third flow rate represents the leakage of hydraulic motor 4; and determining the output flow rate of hydraulic pump 1 based on the first, second, and third flow rates. During the operation of hydraulic motor 4, a certain amount of leakage occurs at hydraulic motor 4. Therefore, when adjusting the speed of hydraulic motor 4 using the output flow rate of hydraulic pump 1, the leakage of hydraulic oil at hydraulic motor 4 should be considered. The leakage of hydraulic motor 4 is related to the pressure at the inlet A of the hydraulic motor. Therefore, the leakage of hydraulic oil at hydraulic motor 4 can be determined based on the pressure at the inlet A of the hydraulic motor. The controller can determine the third flow rate based on the pressure value at the inlet A of the hydraulic motor, which is the leakage of hydraulic motor 4. Furthermore, the controller can determine the output flow rate of hydraulic pump 1 based on the aforementioned first, second, and third flow rates to precisely adjust the speed of hydraulic motor 4. In the third embodiment, the output flow rate of the hydraulic pump 1 is determined based on the leakage of the hydraulic motor 4, the required flow rate of the hydraulic motor 4, and the overflow of the regulating valve 7. This is more accurate than the output flow rate of the hydraulic pump 1 determined in the second embodiment, thereby enabling the controller to more accurately adjust the speed of the hydraulic motor 4.

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

[0054] V = k2P in +k3ω+k4ω (1)

[0055] Where V is the output flow rate of hydraulic pump 1, k2 is the equivalent leakage coefficient of hydraulic motor 4, k3 is the equivalent displacement coefficient of hydraulic motor 4, k4 is the bypass damping coefficient of regulating valve 7, and P in ω is the pressure value at the inlet A of the hydraulic motor, k3ω is the speed value corresponding to the speed control command, k4ω is the first flow rate, k2P is the second flow rate, and k2P is the third flow rate. in This is the third flow.

[0056] In the fourth embodiment, the closed-loop 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 command is less than or equal to a preset speed, the step of adjusting the speed of the hydraulic motor 4 further includes the following steps: when the speed value corresponding to the speed control command is less than or equal to the preset speed, acquiring the actual speed of the hydraulic motor 4; determining a first opening control signal for the regulating valve 7 based on the actual speed and the speed control command. 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 command is less than or equal to the preset speed, the controller can acquire the actual speed of the hydraulic motor 4 and compare the actual speed with the speed corresponding to the speed control command. The controller can adjust the speed based on the difference between the actual speed and the speed corresponding to the speed control command. A regulating valve 7 for adjusting the flow rate of the motor bypass oil circuit is provided on the motor bypass oil circuit. When the flow rate of the motor bypass oil circuit changes, the flow rate and pressure of the hydraulic oil flowing into the hydraulic motor 4 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 command, 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 electro-proportional regulating valve, which can adjust the speed of the hydraulic motor 4 according to the opening degree of the first regulating valve 7 port. The controller determines the first regulating current of the electro-proportional regulating valve based on the pressure difference between the inlet and outlet of the hydraulic motor 4, the speed control command, and a preset third correspondence, and sends the first regulating current to the electro-proportional regulating valve. The preset third correspondence can be a formula, table, or other similar method. After the electro-proportional regulating valve opens according to the first regulating current, the speed sensor acquires the actual speed of the hydraulic motor 4 and transmits the detected value to the controller. The controller compares the actual speed with the speed value corresponding to the speed control command and performs PID regulation on the first regulating current of the electro-proportional regulating valve to adjust the actual speed of the hydraulic motor 4 towards the speed corresponding to the speed control command.

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

[0059]

[0060] Where I1 is the first regulating current, k4 is the bypass damping coefficient of the electro-proportional regulating valve, k5 is the current-displacement coefficient of the electro-proportional regulating valve, ω is the speed value corresponding to the speed control command, and C d Where ρ is the flow coefficient, ρ is the density of the hydraulic oil, and P is the flow coefficient.in P is the pressure value at the oil inlet A of the hydraulic motor. out This is the pressure value at the oil outlet B of the hydraulic motor.

[0061] In one embodiment, such as Figure 3 The diagram shown is a control flowchart for the low-speed operating mode of the hydraulic motor 4 according to an embodiment of the present invention. Step S103 includes the following detailed steps: S202, real-time acquisition of the pressure at the inlet A and outlet B of the hydraulic motor. S204, determination of the required flow rate of the hydraulic motor 4 at the speed value corresponding to the speed control command of the hydraulic pump 1. 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 command. S208, determination of the first regulating current of the electro-proportional regulating valve based on the pressure at the inlet A of the hydraulic motor, the pressure at the outlet B of the hydraulic motor, and the speed value corresponding to the speed control command. S210, control the opening of the electro-proportional regulating valve according to the first regulating current to adjust the speed of the hydraulic motor 4. S212, comparison of the actual speed of the hydraulic motor 4 with the speed corresponding to the speed control command, and adjustment of the regulating current of the electro-proportional regulating valve according to the comparison result so that the hydraulic motor 4 rotates precisely according to the speed corresponding to the speed control command.

[0062] In a specific embodiment, such as Figure 4 The diagram shows the control flow chart for the low-speed operating mode of the hydraulic motor 4 according to a specific embodiment of the present invention. The regulating valve 7 is an electro-proportional directional valve. When the hydraulic motor 4 is in low-speed operating mode, the controller can obtain the speed command of the hydraulic motor 4 and the hydraulic oil pressure at both ends of the hydraulic motor 4, and determine the inlet port A and outlet port B of the hydraulic motor by comparing the pressure at both ends. The output flow rate 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 electro-proportional directional valve is determined according to the above formula (2), and the regulating current of the electro-proportional directional valve is adjusted. The actual speed of the hydraulic motor 4 is obtained, and the regulating current of the electro-proportional directional valve is PID-regulated according to the difference between the speed control command and the actual speed. The electro-proportional directional valve can adjust the valve opening or perform a reversing operation according to the electro-proportional ratio.

[0063] In one embodiment, when the speed value corresponding to the speed control command is greater than a preset speed, adjusting the rotational speed of the hydraulic motor 4 and limiting the pressure at the inlet A of the hydraulic motor by controlling the regulating valve 7 includes the following steps: acquiring the pressure values ​​at the inlet A and outlet B of the hydraulic motor in real time; determining the opening set pressure value of the regulating valve 7 based on the speed value corresponding to the speed control command, the pressure value at the outlet B of the hydraulic motor, and a second preset correspondence, wherein the second preset correspondence is the correspondence between the speed value corresponding to the speed control command, the pressure value at the outlet B of the hydraulic motor, and the opening set pressure value of the regulating valve 7; and opening the regulating valve 7 when the pressure value at the inlet A of the hydraulic motor is greater than the opening set pressure value to reduce the pressure value at the inlet A of the hydraulic motor. When the speed value corresponding to the speed control command is greater than the preset speed, the hydraulic motor 4 is in a high-speed operating mode. In the high-speed operating mode, the pressure at the inlet A of the hydraulic motor may be high during startup and braking, potentially causing damage to the closed-loop motor hydraulic circuit. Therefore, in the high-speed working mode of hydraulic motor 4, when the pressure at the oil inlet 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 A of the hydraulic motor.

[0064] Specifically, when the speed value corresponding to the speed control command is greater than the preset speed, the controller acquires the pressure values ​​at the inlet A and outlet B of the hydraulic motor in real time. Based on the speed value corresponding to the speed control command, the pressure value at the outlet B of the hydraulic motor, and a second preset correspondence, the controller determines the opening set pressure value for adjusting the pressure at the outlet B of the hydraulic motor. The second preset correspondence can be a formula, table, or other method. When the pressure value at the inlet A of the hydraulic motor is greater than the opening set pressure value, the controller can open the regulating valve 7 to divert hydraulic oil in the closed-loop motor hydraulic circuit, reducing the pressure at the inlet A of the hydraulic motor and protecting the hydraulic components in the closed-loop motor hydraulic circuit.

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

[0066]

[0067] Among them, P set To activate the set pressure value, k1 is the pressure impact coefficient, J m The equivalent moment of inertia of hydraulic motor 4 and the load, ω is the speed value corresponding to the speed control command, t is the response time requirement of the controller, and B m V is the viscous resistance coefficient of hydraulic motor 4, T is the load torque of hydraulic motor 4, and V is the viscous resistance coefficient of hydraulic motor 4. m P is the displacement of hydraulic motor 4.out This represents the pressure value at the outlet port B of the hydraulic motor. The controller's response time requirement is related to the controller's own data acquisition frequency or time interval.

[0068] In one embodiment, the step of opening the regulating valve 7 to reduce the pressure at the inlet A of the hydraulic motor when the pressure value at the inlet A is greater than the opening set pressure value includes: determining the pressure difference between the pressure value at the inlet A of the hydraulic motor and the opening set pressure value; determining a second opening control signal for the regulating valve 7 based on the pressure difference, the second opening control signal being used to adjust the opening of the regulating valve 7 to adjust the pressure at the inlet A of the hydraulic motor. The motor bypass oil circuit can divert hydraulic oil flowing into the hydraulic motor 4; the greater the diversion flow, the lower the pressure at the inlet A of the hydraulic motor. The second opening control signal can control the regulating valve 7 to open its 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 at the inlet A of the hydraulic motor, the controller can determine the valve port opening of the regulating valve 7 based on the pressure difference between the pressure value at the inlet A of the hydraulic motor and the opening set pressure, and send the second opening control signal to the regulating valve 7. The second opening control signal is the second regulating current. The larger the value of the second regulating current, the larger the opening of the regulating valve 7. Using the above-described closed-loop motor hydraulic circuit control method, when the pressure at the inlet A of the hydraulic motor is greater than the opening set pressure, the pressure at the inlet A of the hydraulic motor can be adjusted according to the difference between the opening set pressure and the pressure at the inlet A of the hydraulic motor. This ensures that the hydraulic oil pressure is within a safe range, minimizes hydraulic oil diversion, and prevents pressure drop from causing the hydraulic motor 4 to rotate too slowly, thus affecting working efficiency.

[0069] In one 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] I2=k2(P in -P set ) +I de (4)

[0071] Where I2 is the second regulating current, k2 is the equivalent leakage coefficient of the hydraulic motor 4, and P in P is the pressure value at the oil inlet A of the hydraulic motor. set To enable the set pressure value, I de This is the preset current coefficient.

[0072] In one specific embodiment, the controller adjusts the pressure at the oil inlet end A of the hydraulic motor only when the hydraulic motor 4 starts and stops, so as to avoid excessive impact when the hydraulic motor 4 starts and stops.

[0073] In one embodiment, the closed-loop motor hydraulic circuit further includes a speed sensor for detecting the actual rotational speed of the hydraulic motor 4. When the speed value corresponding to the speed control command is greater than a preset speed, the rotational speed of the hydraulic motor 4 is adjusted, and the pressure at the inlet A of the hydraulic motor is limited by controlling the regulating valve 7. The circuit also includes the following steps: obtaining the actual rotational speed of the hydraulic motor 4 when the speed value corresponding to the speed control command is greater than the preset speed; and adjusting the output flow of the hydraulic pump 1 according to the actual rotational speed and the speed control command. In high-speed operating mode, the actual rotational speed of the hydraulic motor 4 is prone to deviating from the speed value corresponding to the speed control command. The controller can obtain the actual rotational speed detected by the speed sensor, compare it with the speed value corresponding to the speed control command, and adjust the output flow of the hydraulic pump 1 according to the comparison result to adjust the rotational speed of the hydraulic motor 4. Using the above-described closed-loop motor hydraulic circuit control method, the speed of the high-speed rotating hydraulic motor 4 can be adjusted to prevent the hydraulic motor 4 from deviating from the rotational speed corresponding to the speed control command, thus 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 rotational speed and the rotational speed corresponding to the speed control command, so that the hydraulic pump 1 outputs the corresponding hydraulic oil and the rotational speed of the hydraulic motor 4 gradually approaches the speed value corresponding to the speed control command.

[0075] In one embodiment, hydraulic pump 1 is a variable displacement pump, such as... Figure 5 The diagram shows the speed control flowchart of the hydraulic motor 4 in high-speed operating mode according to an embodiment of the present invention. Step S102 includes the following detailed steps: S302, real-time acquisition of the pressure at the inlet A and outlet B of the hydraulic motor. S304, determination of the required flow rate of the variable pump based on the speed value corresponding to the speed control command. S306, control of 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 rotating, adjustment of the swing angle of the hydraulic pump 1 based on the acquired actual rotation speed of the hydraulic motor 4 and the speed value corresponding to the speed control command, thereby adjusting the rotation speed of the hydraulic motor 4.

[0076] In addition, such as Figure 6The diagram shows the pressure control flow at the inlet end of the hydraulic motor 4 in high-speed operating mode according to an embodiment of the present invention. The regulating valve 7 is an electro-proportional regulating valve. Step S102 further includes the following refined steps: S402, determining the opening set pressure of the electro-proportional regulating valve based on the speed value corresponding to the speed control command and the outlet pressure value of the hydraulic motor 4. S404, when the pressure at the inlet end A of the hydraulic motor is greater than the opening set pressure, controlling the electro-proportional regulating valve to determine a second regulating current based on the pressure difference between the inlet end A and the outlet end B of the hydraulic motor. S406, adjusting the valve opening of the electro-proportional regulating valve according to the second regulating current to reduce the pressure at the inlet end A of the hydraulic motor.

[0077] In a specific embodiment, such as Figure 7 The diagram shows a flowchart of the pressure control and speed control at the inlet end of the hydraulic motor 4 in high-speed operating mode according to a specific embodiment of the present invention. The regulating valve 7 is an electro-proportional directional valve, and the hydraulic pump 1 is a variable displacement pump. When the hydraulic motor 4 is in high-speed operating mode, the controller can acquire the speed command of the hydraulic motor 4, the controller's acquisition time interval t, and the hydraulic oil pressure at both ends of the hydraulic motor 4. It then compares the pressure at both ends to determine the inlet end A and outlet end B of the hydraulic motor, and determines the opening set pressure value of the electro-proportional directional valve according to the above formula (3). When the hydraulic oil pressure at the inlet end A of the hydraulic motor is greater than the opening set pressure value, the second regulating current of the electro-proportional directional valve is determined according to the above formula (4), and the current of the electro-proportional directional valve is adjusted according to the second regulating current. When the hydraulic oil pressure at the inlet end A of the hydraulic motor is less than or equal to the opening set pressure value, the electro-proportional directional valve closes. Furthermore, in this embodiment of the invention, the rotational 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 rotational speed of the hydraulic motor 4 with the motor speed command, so as to accurately adjust the rotational speed of the hydraulic motor 4.

[0078] The speed of the hydraulic motor 4 is adjusted by regulating the flow rate of the hydraulic pump 1. Furthermore, when the pressure at the inlet A of the hydraulic motor exceeds the set opening pressure, the controller can open the regulating valve 7 to reduce the pressure at the inlet A of the hydraulic motor, preventing damage to the components of the closed-loop motor hydraulic circuit due to excessive pressure.

[0079] In one embodiment, the closed-loop motor hydraulic circuit also includes a replenishing oil circuit, which can replenish the hydraulic oil overflowing from the hydraulic motor 4, hydraulic pump 1 and regulating valve 7, preventing cavities from appearing in the hydraulic pump and hydraulic motor.

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

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

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

[0083] In one embodiment, the replenishing oil circuit also includes a relief valve 5. One end of the relief valve 5 is connected to the oil outlet of the replenishing oil 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 replenishing oil circuit from being too high, which could damage the hydraulic components in the closed motor hydraulic circuit.

[0084] This application embodiment also provides a closed-loop motor hydraulic circuit, including:

[0085] Hydraulic motor 4;

[0086] Hydraulic pump 1 is used to drive hydraulic motor 4 to rotate;

[0087] The motor bypass oil circuit connects the oil inlet A of the hydraulic motor to the oil outlet B of the hydraulic motor and is equipped with a regulating valve 7 for controlling the flow rate of the motor bypass oil circuit.

[0088] And the controller is configured to execute the control method of the closed motor hydraulic circuit described above.

[0089] In one embodiment, a working machine is provided, including the aforementioned closed-loop motor hydraulic circuit.

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

[0091] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0092] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0093] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A control method for a closed-loop motor hydraulic circuit, characterized in that, The closed-loop motor hydraulic circuit includes a hydraulic motor (4), a hydraulic pump (1), and a motor bypass oil circuit. The motor bypass oil circuit connects the inlet end (A) of the hydraulic motor to the outlet end (B) of the hydraulic motor, and is provided with a regulating valve (7) for controlling the flow rate from the inlet end (A) to the outlet end (B) delivered via the motor bypass oil circuit. The control method includes the following steps: Obtain the speed control command of the hydraulic motor (4); When the speed value corresponding to the speed control command is greater than the preset speed, the rotation speed of the hydraulic motor (4) is adjusted, and the flow rate of the bypass oil circuit of the motor is adjusted by controlling the regulating valve (7) to limit the pressure at the oil inlet end (A) of the hydraulic motor. When the speed value corresponding to the speed control command is less than or equal to the preset speed, the rotational speed of the hydraulic motor (4) is adjusted.

2. The control method for a closed-loop motor hydraulic circuit according to claim 1, characterized in that, The step of adjusting the rotational speed of the hydraulic motor (4) when the speed value corresponding to the speed control command is less than or equal to the preset speed includes: If the speed value corresponding to the speed control command is less than or equal to the preset speed, the first flow rate is determined according to the speed control command. The output flow rate of the hydraulic pump (1) is determined based on 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).

3. The control method for a closed-loop motor hydraulic circuit according to claim 2, characterized in that, The step of determining the output flow rate of the hydraulic pump (1) based on the first flow rate includes: The second flow rate is determined according to the speed control command and the first preset correspondence, the second flow rate is the bypass overflow flow rate of the regulating valve (7), and the first preset correspondence is the correspondence between the speed control command and the second flow rate; The output flow rate of the hydraulic pump (1) is determined based on the second flow rate and the first flow rate.

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

5. The control method for a closed-loop motor hydraulic circuit according to any one of claims 1 to 4, characterized in that, The closed-loop motor hydraulic circuit also includes a speed sensor for detecting the actual speed of the hydraulic motor (4). The step of adjusting the speed of the hydraulic motor (4) when the speed value corresponding to the speed control command is less than or equal to the preset speed further includes the following steps: When the speed value corresponding to the speed control command is less than or equal to the preset speed, the actual rotational speed of the hydraulic motor (4) is obtained; Based on the actual rotational speed and the speed control command, a first opening control signal for the regulating valve (7) is determined. The first opening control signal is used to adjust the opening of the regulating valve (7) to regulate the rotational speed of the hydraulic motor (4).

6. The control method for a closed-loop motor hydraulic circuit according to claim 1, characterized in that, When the speed value corresponding to the speed control command is greater than the preset speed, adjusting the rotational speed of the hydraulic motor (4) and limiting the pressure at the oil inlet end (A) of the hydraulic motor by controlling the regulating valve (7) includes the following steps: The pressure values ​​at the oil inlet (A) and the oil outlet (B) of the hydraulic motor are acquired in real time. Based on the speed value corresponding to the speed control command, the pressure value at the oil outlet (B) of the hydraulic motor, and the second preset correspondence, the opening setting pressure value of the regulating valve (7) is determined. The second preset correspondence is the correspondence between the speed value corresponding to the speed control command, the pressure value at the oil outlet (B) of the hydraulic motor, and the opening setting pressure value of the regulating valve (7). When the pressure at the inlet (A) of the hydraulic motor is greater than the set opening pressure, the regulating valve (7) is opened to reduce the pressure at the inlet (A) of the hydraulic motor.

7. The control method for a closed-loop motor hydraulic circuit according to claim 6, characterized in that, The step of opening the regulating valve (7) to reduce the pressure at the inlet (A) of the hydraulic motor when the pressure value at the inlet (A) is greater than the set opening pressure value includes: Determine the pressure difference between the pressure value at the oil inlet end (A) of the hydraulic motor and the opening set pressure value; The second opening control signal of the regulating valve (7) is determined based on the pressure difference. 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 for a closed-loop motor hydraulic circuit according to claim 1, 6, or 7, characterized in that, The closed-loop motor hydraulic circuit also includes a speed sensor for detecting the actual speed of the hydraulic motor (4). The step of adjusting the speed of the hydraulic motor (4) when the speed value corresponding to the speed control command is greater than the preset speed, and limiting the pressure at the oil inlet end (A) of the hydraulic motor by controlling the regulating valve (7) further includes the following steps: If the speed value corresponding to the speed control command is greater than the preset speed, the actual rotational speed of the hydraulic motor (4) is obtained; The output flow of the hydraulic pump (1) is adjusted according to the actual rotational speed and the speed control command.

9. A closed-loop motor hydraulic circuit, characterized in that, include: Hydraulic motor (4); A hydraulic pump (1) is used to drive the hydraulic motor (4) to rotate; A bypass oil circuit for the motor connects the inlet end (A) and the outlet end (B) of the hydraulic motor and is equipped with a regulating valve (7) for controlling the flow rate of the bypass oil circuit; and The controller is configured to perform the control method for a closed motor hydraulic circuit according to any one of claims 1 to 8.

10. A type of operating machinery, characterized in that, Includes the closed-loop motor hydraulic circuit as described in claim 9.

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