CN106762871A - The servo-pump control hydraulic linear drive system and control method of a kind of single-motor double pump - Google Patents

Abstract

The present invention is a single-motor double-pump servo pump-controlled hydraulic linear drive system and its control method. The theoretical displacement of the A and B hydraulic pumps in this system is proportional to the cross-sectional area of the rodless and rod chambers of the hydraulic cylinders. The pumps are respectively connected to the rodless and rod chambers of the hydraulic cylinder, and there are A and B pressure sensors connected to the motion control unit on the pipelines. The two pumps are respectively coupled with the front and rear shaft extensions of the servo motor. The servo drive for driving the servo motor and the displacement sensor on the push rod are connected to the motion control unit. The control method is: when the servo motor rotates forward, pump A rotates forward, oil enters the rodless chamber, and the push rod advances; at the same time, pump B reverses, and oil drains from the rod chamber. On the contrary, the B pump rotates forward, the A pump reverses, and the push rod of the hydraulic cylinder returns. The motion control unit stores process data and control requirements, based on which and the real-time feedback of each sensor, the servo driver's operating instructions are obtained, and the thrust, speed and position of the push rod are precisely controlled. The invention realizes high response frequency and precise position and speed control of the hydraulic cylinder push rod.

Description

A single-motor-double-pump servo pump-controlled hydraulic linear drive system and control method

technical field

The invention relates to a hydraulic transmission control device, specifically a servo pump-controlled hydraulic linear drive system and control method with a single motor and two pumps. The invention uses one servo motor to drive two oil pumps, and then controls the power output of the hydraulic cylinder to realize Control of linear reciprocating motion.

Background technique

It is a common mechanical structure to control linear motion and power output through a hydraulic cylinder. The traditional hydraulic linear drive system is a motor-driven hydraulic pump that runs continuously. The oil circuit composed of various valve groups, sensors and pipelines controls the flow of hydraulic oil. Flow rate, pressure, and then the drive of the hydraulic cylinder. When it is necessary to control the moving speed of the hydraulic cylinder, a proportional directional valve or a proportional directional servo valve is required to adjust the liquid rate entering the hydraulic cylinder; when it is necessary to control the driving force of the hydraulic cylinder, it is necessary to control the overflow pressure of the overflow valve or according to the pressure sensor Feedback and through the proportional pressure valve or proportional pressure servo valve to control the pressure of the liquid entering the hydraulic cylinder, thereby controlling the thrust of the hydraulic cylinder.

This type of traditional hydraulic linear drive system has the following shortcomings: 1. The motor driving the hydraulic pump must run continuously. Even when the hydraulic cylinder movement does not need to be adjusted and controlled, the motor cannot be stopped. It returns to the fuel tank through the valve group again, wasting electric energy. Especially when the hydraulic cylinder outputs thrust but the displacement of the piston is very small or the displacement speed is very low, the high-pressure throttling increases the power consumption of the motor and wastes electric energy; The aging of the seal is accelerated, and the failure rate increases; 3. When the hydraulic oil reciprocates between the rod chamber and the rodless chamber of the hydraulic cylinder, various valve actions need to be controlled, and overflow and liquid filling actions are continuously generated, which increases the System loss, valve failure rate is relatively high; 4. In fast and precise control, it is necessary to use P/Q valve (pressure flow control valve) or servo valve to participate in the control, especially the servo valve is expensive and difficult to maintain, resulting in system failure. The purchase, use and maintenance costs of the equipment have increased significantly; 5. Since the mechanical actions of various valves take a long time to complete, it is impossible to further speed up the switching of various actions in the oil circuit, which directly affects the working rhythm of the equipment.

Patent 201521053147.3 "A Servo Pump-Controlled Hydraulic Linear Drive System" describes a scheme that uses two motors to drive two hydraulic pumps, and then drives the hydraulic cylinder to achieve high-precision, high-response linear reciprocating motion control. Although this solution solves the above-mentioned problems of the traditional hydraulic linear motion mechanism, because it involves the coordinated action of two sets of servo drive systems, its technical difficulty is relatively high, and the economy of the system is not ideal.

Contents of the invention

The object of the present invention is to propose a single-motor-double-pump servo-pump-controlled hydraulic linear drive system and a control method for the deficiencies of the prior art. The theoretical displacement of the two hydraulic pumps A and B is proportional to the cross-sectional area of the rodless cavity and the rod cavity of the hydraulic cylinder, and the liquid outlets of the A and B hydraulic pumps are respectively connected to the rodless cavity and the rod cavity of the hydraulic cylinder. Both A and B hydraulic pumps are forward pumps, the front shaft extension of the servo motor is connected to the A hydraulic pump, and the rear shaft extension is connected to the B hydraulic pump. The servo drive connected to the motion control unit drives the servo motor to run. The signals of the two pressure sensors A and B installed on the oil circuit of the rodless chamber and the rod chamber of the hydraulic cylinder are respectively connected to the motion control unit and installed on the push rod of the hydraulic cylinder. The signal end of the displacement sensor is connected to the motion control unit.

Another object of the present invention is to propose a control method for the above-mentioned single-motor-two-pump servo pump-controlled hydraulic linear drive system, where the servo driver controls the servo motor to drive the A and B hydraulic pumps. When the servo motor rotates forward, the A hydraulic pump runs forward to pump oil, and the B hydraulic pump runs reversely to drain oil; when the servo motor reverses, the A hydraulic pump runs reversely to drain oil, and the B hydraulic pump runs forward to pump oil. According to the motion position and speed control requirements of the push rod and the current displacement signal of the push rod, the motion control unit calculates the control command of the servo drive and sends it to the servo drive to realize the high-speed and precise reciprocating motion of the hydraulic cylinder push rod.

A single-motor double-pump servo pump-controlled hydraulic linear drive system designed by the present invention includes a hydraulic cylinder, two hydraulic pumps, a servo motor, a servo driver and a motion control unit, the piston is connected to a push rod, and the hydraulic cylinder inner cavity It is divided into a rod chamber and a rodless chamber. The rodless chamber of the hydraulic cylinder is connected to the liquid outlet of the A hydraulic pump, and the rod chamber of the hydraulic cylinder is connected to the liquid outlet of the B hydraulic pump. In the present invention, the liquid inlet ends of the A hydraulic pump and the B hydraulic pump are connected to each other, and a liquid storage/accumulator is also connected to this section of the oil circuit. The theoretical displacement of the two hydraulic pumps A and B is proportional to the cross-sectional area of the rodless cavity and the rod cavity of the hydraulic cylinder. Both A and B hydraulic pumps are forward pumps, the front shaft extension of a servo motor is connected to the A hydraulic pump, and the rear shaft extension is connected to the B hydraulic pump; or the A hydraulic pump is a forward pump, and the B hydraulic pump is a reverse pump. Pumps, A, B hydraulic pumps and a shaft extension coupling at the same end of a servo motor. A servo driver is connected to control the servo motor. The control end of the motion control unit is connected to the servo driver. A pressure sensor is installed on the pipe connecting the rodless chamber of the hydraulic cylinder and the outlet end of the hydraulic pump A, and a pressure sensor B is installed on the pipe connecting the rod chamber of the hydraulic cylinder and the outlet end of the hydraulic pump B, and the signal output terminals of the A and B pressure sensors are connected into the motion control unit. The displacement sensor is installed on the push rod of the hydraulic cylinder, and its signal output end is connected to the input end of the motion control unit.

The A relief valve is forwardly connected between the oil passage connecting the rod chamber and the rodless chamber of the hydraulic cylinder, and the B relief valve is reversely connected between the oil passage connecting the rod chamber and the rodless chamber of the hydraulic cylinder. When the liquid pressure difference in the oil passage connected between the rod cavity and the rodless cavity of the hydraulic cylinder exceeds the upper limit set by the overflow valve, the overflow valve conducts for pressure limiting protection.

The motion control unit is a central processor equipped with a communication interface and a man-machine interface.

One of the schemes of the present invention is to install a power-off brake on the shaft of the servo motor. When the system fails to protect the shutdown or power failure, the power-off brake locks the shaft of the servo motor to stop the hydraulic pump from rotating, avoiding the push rod and installation of the hydraulic cylinder. The workpiece on it falls rapidly due to gravity to ensure the safety of the system equipment.

In another solution of the present invention, the servo motor is a three-phase permanent magnet synchronous servo motor, and its three-phase winding is equipped with a power-off normally closed contactor or a power-off normally closed relay. short circuit. When the push rod of the hydraulic cylinder and the workpiece installed on it are pulled down by gravity, the hydraulic oil pushes the two hydraulic pumps to rotate, thereby driving the rotor of the servo motor to rotate in the opposite direction. Due to the short circuit of the three-phase winding of the servo motor, a damping torque is generated. The first hydraulic pump can only rotate slowly, so that the push rod and piston of the hydraulic cylinder slide slowly to the mechanical limit position, so as to protect the safety of the system equipment.

In another solution of the present invention, a protection valve that automatically closes when the power is off is installed on the pipeline connecting the rod chamber or rodless chamber of the hydraulic cylinder to the hydraulic pump, and the protection valve is automatically closed when the system fails to protect the shutdown or power failure , The flow of hydraulic oil is blocked, which can prevent the push rod of the hydraulic cylinder from falling due to the gravity of the workpiece installed on it, which plays a role of safety protection.

The control method of a servo pump-controlled hydraulic linear drive system with a single motor and two pumps proposed by the present invention is as follows: the servo driver drives the servo motor. When the servo motor runs forward, the A hydraulic pump connected to it runs forward, and the B hydraulic pump The pump rotates in reverse. The A hydraulic pump supplies pressure liquid to the rodless chamber of the hydraulic cylinder, the piston of the hydraulic cylinder moves toward the rod chamber, and the push rod outputs power; at the same time, the hydraulic oil in the rod chamber of the hydraulic cylinder is discharged through the B hydraulic pump It goes out to the pipeline connected to the oil inlet of A hydraulic pump and the liquid storage/accumulator; on the contrary, when the servo motor runs in reverse, the B hydraulic pump runs forward, the A hydraulic pump runs reversely, and the B hydraulic pump turns to the hydraulic pressure. The pressure liquid is provided in the rod chamber of the cylinder, and the piston of the hydraulic cylinder moves toward the rodless chamber, and the hydraulic oil in the rodless chamber is discharged through the A hydraulic pump to the pipeline connected to the oil inlet end of the B hydraulic pump and the liquid storage/storage energy device. Due to the difference in the cross-sectional area of the rod chamber and the rodless chamber, the unbalanced part of the pump oil and oil return volume on both sides is balanced by the liquid storage/accumulator. Since the theoretical displacement of A and B hydraulic pumps is proportional to the cross-sectional area of the rodless cavity and the rod cavity of the hydraulic cylinder, when the piston in the hydraulic cylinder moves a certain distance, the oil intake of the rod cavity is the same as that of the rodless cavity. The oil discharge volume is proportional to the theoretical displacement of hydraulic pumps A and B respectively, and the two pumps rotate at the same speed to meet the requirements of the oil intake volume and oil discharge volume of the hydraulic cylinder. When the piston of the hydraulic cylinder moves to the direction of the rodless chamber, the amount of oil discharged from the rodless chamber is greater than the amount of oil entering the rod chamber, and the hydraulic oil discharged from the rodless chamber of the hydraulic cylinder and the A hydraulic pump is pumped by the B hydraulic pump. into the rod chamber of the hydraulic cylinder, and the remaining part enters the liquid storage/accumulator; when the hydraulic cylinder piston moves toward the rod chamber, the amount of oil leaked from the rod chamber is less than the oil volume entering the rodless chamber, and the oil from the hydraulic cylinder All the hydraulic oil discharged from the rod chamber and the B hydraulic pump is pumped into the rod chamber of the hydraulic cylinder through the A hydraulic pump, and the insufficient oil is provided by the liquid storage/accumulator.

The motion control unit stores the process data of the system and the relationship data between the push rod displacement signal and the servo drive control command under different control modes. The speed corresponding to the cylinder push rod moving to a certain moment or the corresponding speed when the push rod moves to a certain position, the motion control unit performs pressure closed-loop calculation according to the control requirements and the received feedback signals of A and B pressure sensors, and obtains the servo drive operation command ; The motion control unit performs speed and position closed-loop calculations according to the control requirements and the current displacement signal of the push rod received from the displacement sensor, and obtains the operation command of the servo drive. The servo motor and A and B hydraulic pumps rotate under the drive of the servo driver, and then adjust the thrust, speed and position of the hydraulic cylinder push rod to achieve precise thrust control, speed control and position control of the push rod.

According to the above control method, the high-speed and precise reciprocating motion of the hydraulic cylinder push rod can be realized. The usual push rod motion methods are divided into the following three modes, namely forward mode, return mode and high-speed reciprocating mode, but the push rod motion is not limited to these three modes. kind of exercise.

Ⅰ. Way forward

The forward mode refers to the movement of the hydraulic cylinder push rod to the direction of the rod cavity, which is divided into two types: fast forward mode (empty travel) and working mode.

Ⅰ-1. Fast forward mode

At this time, the bottom end of the hydraulic cylinder push rod does not bear the resistance of the workpiece, and the movement speed is usually high to improve work efficiency. The motion control unit sends a speed command of high-speed forward rotation to the servo driver. Driven by the servo driver, the servo motor rotates forward at high speed, and the A hydraulic pump runs forward, supplies hydraulic oil into the rodless cavity, and pushes the hydraulic cylinder at a predetermined speed. The push rod of the push rod moves forward, and at the same time, the B hydraulic pump reverses to discharge the hydraulic oil in the rod chamber and send it to the pipeline connected to the oil inlet of the A hydraulic pump.

When the fast-forward mode ends and the work-forward mode is switched, the motion control unit sends an instruction to the servo driver to reduce the speed setting value, so that the speed of the servo motor and the two hydraulic pumps decreases, and the speed of the hydraulic cylinder push rod decreases.

Ⅰ-2. Working method

At this time, the bottom end of the push rod of the hydraulic cylinder bears the resistance of the workpiece, and its movement overcomes the resistance and does work.

The motion control unit sends a speed command to the servo driver for forward rotation at the working speed. Driven by the servo driver, the servo motor rotates forward at the working speed, and the A hydraulic pump supplies hydraulic oil to the rodless cavity, and the predetermined working speed Push the push rod of the hydraulic cylinder forward, and at the same time, the B hydraulic pump reverses to discharge the hydraulic oil in the rod cavity and send it to the oil circuit connected to the inlet of the A hydraulic pump.

Ⅱ. Return method

The return stroke means that the push rod of the hydraulic cylinder moves in the direction of the rodless chamber. The motion control unit sends a speed command for reverse rotation to the servo driver, and the servo motor rotates reversely under the drive of the servo driver. At this time, the B hydraulic pump rotates forward, supplies hydraulic oil into the rod cavity, and pushes the piston push rod The return stroke in the direction of the cavity; the A hydraulic pump is reversed, and the hydraulic oil in the rodless cavity is pumped out, and sent to the pipeline connected to the oil inlet of the B hydraulic pump and the liquid storage/accumulator; the hydraulic oil part leaked from the rodless cavity of the hydraulic cylinder It is pumped into the rod cavity of the hydraulic cylinder through the B hydraulic pump, and the excess part is temporarily stored in the liquid storage/accumulator.

In the return mode and the forward mode, the motion control unit adjusts the speed command of the servo driver in real time according to the control requirements and the displacement feedback value of the displacement sensor, and controls the speed of the servo motor, so as to realize the precise control of the position and speed of the hydraulic cylinder push rod.

In the above motion control, in order to obtain the thrust of the push rod, the motion control unit calculates the thrust of the push rod according to the feedback signals of the connected A and B pressure sensors and the pre-stored cross-sectional area data of the rod chamber and the rodless chamber of the hydraulic cylinder, and then calculates the thrust of the push rod. The thrust of the rod is controlled, and the thrust in the speed and position control is feed-forward controlled.

Ⅲ. High-speed reciprocating mode

The high-speed reciprocating mode is the high-speed repetition of the above-mentioned working mode and return mode. At this time, there is no fast-forward mode, and the hydraulic cylinder is in the reciprocating motion state of "working-returning-working...". The motion control unit predetermines the arrival position and/or arrival time of the push rod as the basis for judging the end of the work progress or the end of the return journey, and judges the end of the work progress or the end of the return journey according to the displacement signal and/or time of the displacement sensor, and realizes the return mode or the work progress mode cycle conversion. Since the response frequency of the servo motor driven by the servo driver is very high, it can realize fast forward and reverse switching. The servo drive device of this system can realize high-precision and high-repeatability reciprocating motion of more than ten to tens of hertz.

Compared with the prior art, the present invention has the beneficial effects of a servo pump-controlled hydraulic linear drive system and control method with a single motor and two pumps: 1. One servo motor simultaneously drives two hydraulic pumps to control the power of the hydraulic cylinder. 2. The response frequency and speed control accuracy of the servo motor and servo drive are high, so the system can achieve a response frequency of up to ten to tens of hertz and a position with a precision of more than ten microns or even microns Control; 3. The hydraulic valves in the system pipeline are only two overflow valves for hydraulic protection, and do not need other solenoid valves, P/Q valves or servo valves. The system has simple structure, low cost and high reliability.

Description of drawings

Fig. 1 is a schematic structural diagram of an embodiment of a servo pump-controlled hydraulic linear drive system with a single motor and two pumps.

Marks in the figure: 1. Hydraulic cylinder; 2. A relief valve (AF); 3. B relief valve (BF); 4. A pressure sensor (AP); 5. A hydraulic pump (AU); 6. Servo Motor (M); 7. Fluid storage/accumulator (CY); 8. Servo driver (S); 9. Motion control unit (YK); 10. B hydraulic pump (BU); 11. B pressure sensor (BP ); 12. Displacement sensor.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment of Servo Pump Control Hydraulic Linear Drive System with Single Motor and Two Pumps

The embodiment of the servo pump-controlled hydraulic linear drive system with single motor and double pumps is shown in Figure 1. The solid lines connecting the components in the figure indicate the oil pipelines connecting the components, and the dotted lines indicate the signal lines of the sensors and the motion control unit. The control signal line, the signal line between the servo driver and the servo motor and the electric power connection line, the double solid line connecting the servo motor and the hydraulic pump indicate that the two are coaxial.

The inner cavity of the hydraulic cylinder 1 is divided into a rod cavity and a rodless cavity. The rodless cavity of the hydraulic cylinder 1 is connected to the liquid outlet of the A hydraulic pump 5 (AU in the figure), and the rod cavity of the hydraulic cylinder 1 is connected to the The liquid outlet of B hydraulic pump 10 (shown as BU in the figure) is connected. The liquid inlet ends of the A hydraulic pump 5 and the B hydraulic pump 10 are connected by a pipeline, and at the same time are connected to the liquid storage/accumulator 7 (shown as CY in the figure). The theoretical displacement of the A hydraulic pump 5 and the B hydraulic pump 10 is proportional to the area of the rodless cavity and the rod cavity of the hydraulic cylinder 1 . In this example, the A hydraulic pump 5 and the B hydraulic pump 10 are both forward pumps. The front shaft extension of the servo motor 6 (shown as M in the figure) is connected with the A hydraulic pump 5, and the rear shaft is connected with the B hydraulic pump 10. The servo driver 8 (shown as S in the figure) is connected to control the servo motor 6 . The control end of the motion control unit 9 (shown as YK in the figure) is connected to the servo driver 8 . Installed on the signal output end of A pressure sensor 4 (AP shown in the figure) on the pipeline connecting the rodless chamber of hydraulic cylinder 1 and the liquid outlet of hydraulic pump A and hydraulic cylinder 1 and the liquid outlet of hydraulic pump B 10 The signal output ends of the B pressure sensor 11 (BP shown in the figure) installed on the pipeline at the end are all connected to the motion control unit 9 . The displacement sensor 12 is installed on the push rod of the hydraulic cylinder 1 , and its signal output end is connected to the input end of the motion control unit 9 .

There are two relief valves connected between the pipe on the side of the rod chamber and the pipe on the side of the rodless chamber of hydraulic cylinder 1: A relief valve 2 (shown as AF in the figure) is positively connected, and B is overflowing Valve 3 (shown as BF in the figure) is reverse bridged. When the pressure difference between the oil circuit connected to the rod chamber and the rodless chamber of the hydraulic cylinder 1 exceeds the allowable value, the overflow valve is turned on to protect the safety of the oil circuit.

In this example, the motion control unit is a central processor, equipped with a communication interface and a man-machine interface.

In order to ensure that the push rod of hydraulic cylinder 1 will not be pulled out of control by the load under abnormal conditions, for safety reasons, the servo motor in this example is equipped with a power-off brake (not shown in the figure). The brake locks the shaft of the servo motor.

Other protection schemes can also be used, such as: installing a protection valve that automatically closes when the power is off on the pipeline connected to the hydraulic cylinder 1. When the system fails to protect the shutdown or power failure, the protection valve can shut off the rod chamber of the hydraulic cylinder The oil passage on the side or the side of the rodless chamber plays a protective role.

Or, when the servo motor 6 is a three-phase permanent magnet synchronous servo motor, its three-phase winding is equipped with a power-off normally closed contactor or a power-off normally closed relay. The closed contactor or the power-off normally closed relay is short-circuited, and the braking force of the permanent magnet synchronous motor winding short-circuit is used to ensure the safety of the system.

Embodiment of a control method for a servo pump-controlled hydraulic linear drive system with a single motor and two pumps

The embodiment of the control method of the single-motor-two-pump servo-pump-controlled hydraulic linear drive system adopts the above-mentioned embodiment of the single-motor double-pump servo-pump-controlled hydraulic linear drive system. When the servo driver 8 drives the servo motor 6 to run forward, the A hydraulic pump 5 connected to it runs forward to provide pressure liquid to the rodless chamber of the hydraulic cylinder 1, and the piston of the hydraulic cylinder 1 moves toward the rod chamber, pushing The rod outputs power; at the same time, the B hydraulic pump 10 runs in reverse, and the hydraulic oil in the rod cavity of the hydraulic cylinder 1 is discharged to the pipeline connected to the oil inlet of the A hydraulic pump through the B hydraulic pump 10. At this time, the rod cavity After the hydraulic oil is discharged, all the hydraulic oil is pumped to the rodless chamber of the hydraulic cylinder 1 through the A hydraulic pump, and the insufficient hydraulic oil is provided by the liquid storage/accumulator 7. Conversely, when the servo motor 6 rotates in the reverse direction, the B hydraulic pump 10 connected to the shaft rotates forward to provide pressure liquid to the rod chamber of the hydraulic cylinder 1, and the piston of the hydraulic cylinder 1 moves toward the rod chamber. At the same time, A The hydraulic pump 5 runs in reverse, and the hydraulic oil in the rodless chamber of the hydraulic cylinder 1 is discharged through the A hydraulic pump 5 to the pipeline connected to the oil inlet of the B hydraulic pump and the liquid storage/accumulator. Part of the output hydraulic oil is pumped to the rod cavity of the hydraulic cylinder 1 through the B hydraulic pump 10 , and the rest of the hydraulic oil enters the liquid storage/accumulator 7 .

The motion control unit 9 stores the process data of the system and the relationship data between the push rod displacement signal and the servo driver control command under different control modes. The motion control unit 9 accepts the control requirements input by the man-machine interface, and the control requirements are set according to the work requirements. Determine the push rod thrust, moving speed or positioning position of the hydraulic cylinder 1, and the motion planning of these control quantities over time. The motion control unit 9 performs the closed-loop calculation of the thrust of the hydraulic cylinder 1 according to the control requirements and the received feedback signals of the A and B pressure sensors, and obtains the operating speed and torque command of the servo driver, thereby controlling the push rod thrust of the hydraulic cylinder 1; the motion control unit 9 According to the control requirements and the received push rod position signal feedback from the displacement sensor 12, the speed and position closed-loop calculations are performed to obtain the servo drive speed and torque commands, thereby controlling the push rod movement speed and position of the hydraulic cylinder 1. Realize precise thrust control, speed control and position control of the push rod.

According to the above control method, the high-frequency response and precise reciprocating motion of the push rod of the hydraulic cylinder 1 are realized. The push rod movement mode is mainly divided into the following three modes, namely, the forward mode, the return mode and the high-speed reciprocating mode.

Ⅰ. Way forward

The forward mode refers to that the push rod of the hydraulic cylinder 1 moves toward the direction of the rod cavity. The motion control unit 9 sends a forward rotation speed command to the servo driver 8, the servo driver 8 drives the servo motor 6 to rotate forward, the A hydraulic pump 5 runs forward, and supplies hydraulic oil into the rodless chamber of the hydraulic cylinder 1, according to the predetermined The speed pushes the push rod of hydraulic cylinder 1 forward, and at the same time, the hydraulic oil in the rod cavity of hydraulic cylinder 1 is discharged to the pipeline connected to the oil inlet of A hydraulic pump 5 through B hydraulic pump 10, and the hydraulic oil leaked from the rod cavity All the oil is pumped into the rodless chamber of the hydraulic cylinder 1 through the A hydraulic pump 5, and the insufficient part of the oil is made up by the liquid storage/accumulator 7.

Ⅱ. Return method

The return mode means that the push rod of hydraulic cylinder 1 moves in the direction of the rodless cavity. The motion control unit 9 sends a speed command for reverse rotation to the servo driver 8, the servo driver 8 drives the servo motor 6 to rotate in the reverse direction, the B hydraulic pump 10 rotates forward, pumps hydraulic oil into the rod chamber of the hydraulic cylinder 1, and pushes the piston The push rod returns to the direction of the rodless chamber. The hydraulic oil leaked from the rodless chamber of the hydraulic cylinder 1 enters the pipeline connected to the oil inlet of the hydraulic pump 10 of B and the liquid storage/accumulator through the A hydraulic pump 5, and the hydraulic oil leaked from the rodless chamber passes through the B hydraulic pump 10 is pumped into the rod cavity of the hydraulic cylinder 1, and the excess part is temporarily stored in the liquid storage/accumulator 7.

In the above motion control, in order to obtain the thrust of the push rod, the motion control unit 9 calculates the thrust of the push rod according to the feedback signals of the connected A and B pressure sensors and the pre-stored rod cavity and rodless cavity cross-sectional area data of the hydraulic cylinder 1 , control the thrust of the push rod, and perform feed-forward control on the thrust in speed and position control.

Ⅲ. High-speed reciprocating mode

The high-speed reciprocating mode is a high-speed repetition of the above-mentioned forward mode and return mode. Since the response frequency of the servo drive 8 driving the servo motor 6 is very high, fast forward and reverse switching can be realized, and the servo drive device of this system can realize high-precision, high-repeatability reciprocating motion of tens to tens of Hz.

The above-mentioned embodiments are only specific examples for further specifying the purpose, technical solutions and beneficial effects of the present invention, and the present invention is not limited thereto. Any modifications, equivalent replacements, improvements, etc. made within the disclosed scope of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A servo pump-controlled hydraulic linear drive system with a single motor and two pumps, including a hydraulic cylinder (1), A hydraulic pump (5) and B hydraulic pump (10), a servo motor (6), and a servo driver (8) And the motion control unit (9), the piston is connected with the push rod, and the inner cavity of the hydraulic cylinder (1) is divided into a rod cavity and a rodless cavity, and the rodless cavity of the hydraulic cylinder (1) is connected with the outlet of the A hydraulic pump (5) The liquid end is connected, and the rod cavity of the hydraulic cylinder (1) is connected with the liquid outlet of the B hydraulic pump (10); it is characterized in that: The liquid inlet ends of the A hydraulic pump (5) and the B hydraulic pump (10) are connected to each other, and a liquid storage/accumulator (7) is also connected to this section of the oil circuit; A and B two hydraulic pumps (5 , 10) The theoretical displacement is proportional to the rodless cavity and the rod cavity sectional area of the hydraulic cylinder (1); A, B hydraulic pumps (5, 10) are forward pumps, and a servo motor (6) front axle The rear shaft extension is connected to the A hydraulic pump (5), and the rear shaft is connected to the B hydraulic pump (10); or the A hydraulic pump (5) is a forward pump, and the B hydraulic pump (10) is a reverse pump. The hydraulic pump (5, 10) and the shaft extension coupling at the same end of a servo motor (6); a servo driver (8) is connected to control the servo motor (6); the control end of the motion control unit (9) is connected to the Servo driver (8) described above; A pressure sensor (4) is installed on the pipe connecting the rodless chamber of hydraulic cylinder (1) and hydraulic pump A (5) on the liquid outlet, and the rod chamber of hydraulic cylinder (1) is connected with hydraulic pump B ( 10) The B pressure sensor (11) is installed on the liquid outlet pipeline, and the signal output terminals of the A and B pressure sensors (4, 11) are connected to the motion control unit (9); the displacement sensor (12) is installed on the hydraulic cylinder (1) A push rod, whose signal output end is connected to the input end of the motion control unit (9); The motion control unit (9) is a central processor equipped with a communication interface and a man-machine interface. 2. The servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 1, characterized in that: A relief valve (2) is positively connected between the oil circuit connecting the rod chamber and the rodless chamber of the hydraulic cylinder (1), and the B relief valve (3) is reversely connected to the hydraulic cylinder (1). Between the rod cavity and the oil passage of the rodless cavity. 3. The servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 1, characterized in that: A power-off brake is installed on the shaft of the servo motor (6), and when the system fails to protect and shut down or loses power, the power-off brake locks the shaft of the servo motor (6). 4. The servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 1, characterized in that: The servo motor (6) is a three-phase permanent magnet synchronous servo motor, and its three-phase winding is equipped with a power-off normally closed contactor or a power-off normally closed relay. The normally closed contactor or the normally closed relay is shorted. 5. The servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 1, characterized in that: On the pipeline of the rod chamber side or the rodless chamber side of the hydraulic cylinder (1), a protection valve that is automatically closed when the power is cut off is installed. When the system fails to protect the shutdown or power failure, the protection valve is automatically closed. 6. The control method of the single-motor double-pump servo pump-controlled hydraulic linear drive system according to any one of claims 1 to 5, characterized in that: The servo driver (8) drives the servo motor (6), and when the servo motor (6) runs forward, the A hydraulic pump (5) connected to it runs forward, and the B hydraulic pump (10) rotates reversely; The hydraulic pump (5) supplies pressure liquid to the rodless cavity of the hydraulic cylinder (1), the piston of the hydraulic cylinder (1) moves toward the rod cavity, and the push rod outputs power; at the same time, the hydraulic cylinder (1) has a The hydraulic oil in the rod cavity is discharged through the B hydraulic pump (10) to the pipeline connected to the oil inlet of the A hydraulic pump (5) and the liquid storage/accumulator (7); otherwise, when the servo motor (6) reverses When running in the forward direction, the B hydraulic pump (10) runs forward, and the A hydraulic pump (5) runs reversely, and the B hydraulic pump (10) provides pressure liquid to the rod chamber of the hydraulic cylinder (1), and the hydraulic cylinder (1) The piston moves toward the rodless chamber, and the hydraulic oil in the rodless chamber is discharged through the A hydraulic pump (5) to the pipeline connected to the oil inlet end of the B hydraulic pump (10) and the liquid storage/accumulator (7). 7. The control method of the servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 6, characterized in that: The motion control unit (9) stores the process data of the system and the relationship data between the push rod displacement signal and the control command of the servo driver (8) under different control modes, and the motion control unit (9) accepts the control requirements input by the man-machine interface, The control requirement is to set the corresponding speed when the push rod of the hydraulic cylinder (1) moves to a certain moment or the corresponding speed when the push rod moves to a certain position according to the work requirements, and the motion control unit (9) according to the control requirements and the received A and B pressure sensors (4, 11) feedback signals to perform pressure closed-loop calculations to obtain the servo drive (8) operating instructions; the motion control unit (9) according to the control requirements and the current displacement signal of the push rod received from the displacement sensor (12) Carry out the closed-loop operation of speed and position to obtain the operation command of the servo driver (8); the servo motor (6) and A, B hydraulic pumps (5, 10) rotate under the drive of the servo driver (8), and then adjust the hydraulic cylinder (1 ) thrust, speed and position of the push rod to realize precise thrust control, speed control and position control of the push rod. 8. The control method of the servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 6, characterized in that: The push rod movement modes of the hydraulic cylinder (1) are divided into three types: forward mode, return mode and high-speed reciprocating mode; Ⅰ. Way forward The forward mode refers to the movement of the push rod of the hydraulic cylinder (1) to the direction of the rod cavity, which is divided into two types: fast forward mode and working mode; Ⅰ-1. Fast forward mode At this time, the bottom end of the push rod of the hydraulic cylinder (1) does not bear the resistance of the workpiece, and the motion control unit (9) sends a high-speed forward rotation speed command to the servo driver (8), and the servo motor (6) is driven by the servo driver (8). ) high-speed forward rotation, A hydraulic pump (5) forward rotation, supply hydraulic oil into the rodless chamber, push the push rod of hydraulic cylinder (1) forward at a predetermined speed, at the same time, B hydraulic pump (10) reverse Running, the hydraulic oil in the rod chamber will be released, and sent to the pipeline connected to the oil inlet of A hydraulic pump (5); When the fast-forward mode ends and the work-forward mode is switched, the motion control unit sends an instruction to the servo driver to reduce the speed setting value, so that the speed of the servo motor (6) and A, B hydraulic pumps (5, 10) decreases, and the hydraulic cylinder ( 1) The speed of the push rod is reduced; Ⅰ-2. Working method At this time, the bottom end of the push rod of the hydraulic cylinder (1) bears the resistance of the workpiece, and the motion control unit (9) sends a speed command to the servo driver (8) to rotate forward at the working speed. Driven by the servo driver (8), the servo motor ( 6) Rotate in the forward direction according to the working speed, A hydraulic pump (5) supplies hydraulic oil into the rodless cavity, and pushes the push rod of the hydraulic cylinder (1) forward according to the predetermined working speed, at the same time, B hydraulic pump (10) Reverse operation, the hydraulic oil in the rod cavity is discharged, and sent to the oil circuit connected to the inlet of the A hydraulic pump (5); Ⅱ. Return method The return stroke means that the push rod of the hydraulic cylinder (1) moves in the direction of the rodless chamber; the motion control unit (9) sends a speed command for reverse rotation to the servo driver (8), and the servo motor (6) is driven by the servo driver (8) ) reverse rotation, at this time, the B hydraulic pump (10) rotates forward, supplies hydraulic oil into the rod chamber, and pushes the piston push rod to return to the direction of the rodless chamber; the A hydraulic pump (5) reverses, and the rodless chamber The internal hydraulic oil is pumped out and sent to the pipeline connected to the oil inlet of the B hydraulic pump (10) and the liquid storage/accumulator (7; the hydraulic oil leaked from the rodless cavity of the hydraulic cylinder (1) passes through the B hydraulic pump (10 ) is pumped into the rod cavity of the hydraulic cylinder (1), and the excess part is temporarily stored in the liquid storage/accumulator (7); Ⅲ. High-speed reciprocating mode The high-speed reciprocating mode is the high-speed repetition of the above-mentioned working mode and return mode. The arrival position and/or arrival time of the predetermined push rod of the motion control unit (9) are used as the judgment basis for the end of the work or the end of the return. According to the displacement sensor (12) Displacement signal and/or time judges the end of work progress or the end of return journey, and realizes the cyclic conversion of return mode or work progress mode. 9. The control method of the servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 8, characterized in that: The motion control unit (9) adjusts the speed command of the servo driver (8) in real time according to the control requirements and the displacement feedback value of the displacement sensor (12) in the return mode and the forward mode, controls the speed of the servo motor (6), and realizes the hydraulic cylinder ( 1) The position and speed of the push rod are precisely controlled. 10. The control method of the servo pump-controlled hydraulic linear drive system with single motor and double pumps according to claim 8, characterized in that: The motion control unit (9) calculates the thrust of the push rod according to the feedback signals of the connected A and B pressure sensors (4, 11) and the prestored rod chamber and rodless chamber cross-sectional area data of the hydraulic cylinder (1), and the push rod The thrust is controlled, and the thrust in the speed and position control is feed-forward controlled.