CN111237178A - Sequence control loop for servo motor driven constant delivery pump - Google Patents

Abstract

A sequential control circuit for a servo motor to drive a quantitative pump is characterized in that it includes an oil outlet pipeline, an oil return pipeline and a double pump driven by the servo motor, and the double pump includes a coaxially arranged first quantitative pump and For the second quantitative pump, the oil outlet of the first quantitative pump is communicated with the oil outlet pipeline, and the oil outlet of the second quantitative pump is communicated with the oil outlet pipeline through a branch; The reversing valve of the reversing valve and the oil return port, the oil inlet of the reversing valve is connected with the oil outlet of the second quantitative pump, the first working port of the reversing valve is connected with the oil outlet pipeline, and the oil return port of the reversing valve is connected with the oil outlet of the second quantitative pump. The oil return line is connected. When the oil pressure of the oil outlet line is lower than the set pressure, the oil inlet of the reversing valve and the first working port are connected. When the oil pressure of the oil outlet line reaches the set pressure, change the Conduction to the inlet and return ports of the valve. The invention relates to a sequence control circuit for a servo motor to drive a quantitative pump, which is more energy-saving and can reduce the heat generation of a hydraulic system.

Description

A Sequence Control Loop for Servo Motor-Driven Quantitative Pumps

technical field

The invention relates to the technical field of power systems, in particular to a sequential control loop used for a servo motor to drive a quantitative pump.

Background technique

The hydraulic transmission system of the rolling mill includes five parts: power element, executive element, control element, auxiliary element (accessory) and working medium. The power element converts the mechanical energy of the power machine into the pressure energy of the working medium, and the control element controls the pressure and flow of the working medium. and flow direction, and transmit the pressure energy of the working medium to the actuator, and the actuator converts the pressure energy of the working medium into mechanical energy, output force and speed (ie linear motion), or torque and rotational speed (ie rotary motion). Among them, the power element and the power machine together constitute the power source of the hydraulic transmission system of the rolling mill.

At present, in order to meet the control requirements of the output flow and pressure of the power source, the power source of the hydraulic transmission system of the rolling mill mainly includes the following two modes:

The first one is the power source of the variable pump, which mainly provides a rotating power of a fixed speed through a three-phase asynchronous motor, so that the variable pump can be set according to the flow value of the upper computer, and the actual displacement of the oil pump is adjusted by the displacement proportional valve, and the proportional The pressure valve regulates the pressure required by the actuator. When the operating pressure of the actuator is greater than the set value, the oil discharged from the oil pump flows back to the oil tank through the proportional pressure valve.

The second is the servo power source, which mainly uses the servo driver to control the servo synchronous motor to output different speeds, thereby driving the quantitative pump to output different flow rates, and the rotational movement of the motor is closed-loop controlled by the speed encoder to stabilize each cycle. During the same action, the flow rate output by the quantitative pump is also closed-loop controlled by the pressure sensor to the torque of the rotational motion of the motor to stabilize the pressure of the same action in each cycle. The relief valve plays a safety protection role in the system. This servo power system can provide more accurate pressure and flow according to the needs of each action, without generating excess flow loss, and is more energy-efficient than the first variable pump system, so it is widely used.

Usually, the actuators of the hydraulic transmission system of the rolling mill need a large flow when starting, and the demand is small under normal working conditions, and because there is a certain internal leakage in the hydraulic transmission system, in order to keep the pressure of the hydraulic system stable, no matter which of the above Power source, the single pump runs at high pressure and low flow under normal working conditions, and excess hydraulic oil flows back to the oil tank through the relief valve, which will cause a lot of power loss, low energy conversion efficiency, and lost power. Converted into heat, the temperature of the hydraulic transmission system will increase, and the service life of the hydraulic system will be shortened. Therefore, it is still necessary to further improve the power source.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a sequential control circuit for a servo motor to drive a quantitative pump, which is more energy-saving and can reduce the calorific value of the hydraulic transmission system in view of the above-mentioned technical situation.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a sequential control circuit for a servo motor to drive a quantitative pump, which is characterized in that it includes an oil outlet pipeline, an oil return pipeline and a double pump driven by the servo motor, The duplex pump includes a first quantitative pump and a second quantitative pump coaxially arranged, the oil outlet of the first quantitative pump is communicated with the oil outlet pipeline, and the oil outlet of the second quantitative pump is communicated with the oil outlet pipeline through a branch;

The branch circuit is provided with a reversing valve having an oil inlet, a first working port and an oil return port, the oil inlet of the reversing valve is communicated with the oil outlet of the second quantitative pump, and the reversing valve The first working port of the valve is communicated with the oil outlet line, the oil return port of the reversing valve is communicated with the oil return line, and when the oil pressure of the oil outlet line is lower than the set pressure, the The oil inlet and the first working port of the reversing valve are connected, and when the oil pressure of the oil outlet pipeline reaches the set pressure, the oil inlet and the oil return port of the reversing valve are connected.

In the hydraulic station of the rolling mill, the actuator is mainly a depressing oil cylinder, and the difference between the large flow required for the actuator to start and the small flow required for normal working conditions is not large. Therefore, in order to better adapt to the rolling mill’s actuator Power demand, the first quantitative pump is a large-flow low-pressure pump, and the second quantitative pump is a small-flow high-pressure pump. Under normal working conditions, the power source continues to supply oil through a large-flow low-pressure pump, so that the power source can support more types of actuator actions, and the power source has a wider range of applications.

In order to control the reversing of the reversing valve, it also includes an oil discharge pipeline and a sequence valve for controlling the reversing valve to change its internal hydraulic oil flow state. The sequence valve has an oil inlet and an oil outlet. The oil inlet of the sequence valve is communicated with the oil outlet pipeline, and the opening pressure of the sequence valve is the set pressure; the reversing valve is a hydraulic reversing valve with a control port, and the hydraulic reversing valve One way of the control port is communicated with the oil outlet of the sequence valve, and the other way is communicated with the oil discharge pipeline.

When the oil pressure of the oil outlet pipeline is lower than the opening pressure of the sequence valve, the valve port of the sequence valve is closed, the oil inlet and the oil outlet of the hydraulic reversing valve are connected, and the second quantitative pump and the first quantitative pump supply oil at the same time; When the oil pressure of the oil outlet pipeline rises to the opening pressure of the sequence valve, the valve port of the sequence valve is opened, and the control port of the hydraulic reversing valve enters oil so that the oil inlet and the oil return port of the hydraulic reversing valve are connected, and the second quantitative The pump is unloaded, and only the first quantitative pump supplies oil; when the oil pressure of the oil outlet pipeline is reduced to the opening pressure of the sequence valve due to the large flow operation and other working conditions, the valve port of the sequence valve is closed again, and the hydraulic reversing valve The control port of the hydraulic reversing valve no longer receives oil, and the remaining oil flows into the oil discharge pipeline through the control port of the hydraulic reversing valve, so that the hydraulic reversing valve is reset, and the oil inlet and outlet of the hydraulic reversing valve are connected again. Make the second metering pump and the first metering pump supply oil at the same time again.

The hydraulic reversing valve is controlled by the sequence valve. Compared with the electromagnetic reversing valve, which needs to be controlled by an external controller, the hydraulic control method of the reversing valve can not only realize self-control, but also make the control signal transmission more reliable, and the operation is not easy. error; moreover, the hydraulic oil flowing out of the small-flow high-pressure pump will have a greater impact when reversing inside the reversing valve, and the hydraulic control method can delay this impact and make the control system run more stably.

In order to delay the reset action of the hydraulic reversing valve, a damper for adjusting the reset time of the hydraulic reversing valve is provided between the control port of the hydraulic reversing valve and the oil discharge pipeline or on the oil discharge pipeline. The setting of the damper can protect the control circuit and the reversing valve.

In order to accelerate the unloading of the second quantitative pump, the reversing valve further has a second working port that is communicated with the oil return line, and when the oil pressure of the oil outlet line reaches the set pressure, the changeover valve The oil inlet port of the valve is also communicated with the second working port. When the oil pressure of the oil outlet pipeline reaches the set pressure, the hydraulic oil flowing out from the oil outlet of the second quantitative pump is simultaneously unloaded through the second working port and the oil return port of the reversing valve, and the unloading is faster. .

In order to make the hydraulic oil flowing out from the second working port of the reversing valve quickly enter the oil return line, a first check valve is provided between the second working port of the reversing valve and the oil return line, and the The inlet of the first check valve is communicated with the second working port of the reversing valve, and the outlet of the first check valve is communicated with the oil return pipeline.

In order to enable the hydraulic oil of the double pump to quickly enter the oil outlet pipeline, the oil outlet pipeline is provided with a second one-way valve, and the branch is provided with a third one-way valve behind the reversing valve. The inlet of the third one-way valve is communicated with the first working port of the reversing valve, and the outlet of the third one-way valve and the oil outlet of the first quantitative pump are both connected with the second one-way valve. The inlet of the valve is connected. In this way, the hydraulic oil flowing out of the second quantitative pump can flow out through the third one-way valve and join with the hydraulic oil flowing out of the first quantitative pump to enter the second one-way valve.

In order to protect the control circuit, it also includes a first relief valve with an oil inlet and an oil outlet, the oil inlet of the first relief valve is communicated with the oil outlet pipeline, and the outlet of the first relief valve The oil port is communicated with the oil return line.

Similarly, in order to protect the control circuit, it also includes a second relief valve with an oil inlet and an oil outlet, the oil inlet of the second relief valve is communicated with the branch, the second relief valve The oil outlet is communicated with the oil return line.

In order to detect the pressure of hydraulic oil, a first pressure gauge is arranged on the oil outlet pipeline, and a second pressure gauge is arranged on the branch.

Compared with the prior art, the present invention has the advantages that the servo motor is used to drive the double pump as the power source of the hydraulic transmission system of the rolling mill, and when the actuator is started, the first quantitative pump and the second quantitative pump are combined to supply the power supply. Oil, the servo motor runs at high speed to meet the large flow required when the actuator starts, and in normal working conditions, the reversing valve changes direction in response to the oil pressure of the oil outlet pipeline, so that the second quantitative pump is unloaded, and only the first quantitative pump is unloaded. A certain amount of oil is supplied by the pump, and the servo motor runs at a low speed to meet the small flow required for the normal operation of the actuator, which can effectively reduce the power loss, improve the energy conversion efficiency, reduce the heat generation of the hydraulic system, and prolong the hydraulic system. The first quantitative pump is a large-flow low-pressure pump, and the second quantitative pump is a small-flow high-pressure pump, so that the power source can still supply oil to the large-flow low-pressure pump under normal working conditions, which not only makes the power source more efficient It is well adapted to the power requirements of the actuators of the rolling mill, and also enables the power source to support more types of actuator actions, and the power source has a wider range of applications; controlling the reversing of the hydraulic reversing valve through the sequence valve, compared with the need to combine As far as the electromagnetic directional valve used in the control element is concerned, it can not only realize self-control, make the control signal transmission more reliable, and make the operation less prone to errors, but also delay the hydraulic oil flowing out of the small flow high-pressure pump when it changes direction inside the directional valve. impact, make the control system run more stably.

Description of drawings

FIG. 1 is a schematic diagram of the connection of a sequence control loop used for a servo motor to drive a quantitative pump in an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the embodiments of the accompanying drawings.

As shown in FIG. 1 , the sequence control circuit involved in this embodiment for the servo motor to drive the quantitative pump includes the servo motor 1, the double pump, the oil outlet pipeline 31, the oil return pipeline 32, the oil discharge pipeline 33, the branch circuit 34. Reversing valve 4, sequence valve 5, damper 6, first check valve 71, second check valve 72, third check valve 73, first relief valve 81, second relief valve 82, The first pressure gauge 91 and the second pressure gauge 92 .

As shown in Figure 1, the double pump is driven by a servo motor 1. The double pump includes a first quantitative pump 11 and a second quantitative pump 12 arranged coaxially. The oil outlet of the first quantitative pump 11 is communicated with the oil outlet pipeline 31, and the oil outlet of the second quantitative pump 12 passes through the branch circuit. 34 communicates with the oil outlet pipeline 31 . The branch line 34 is provided with a reversing valve 4 having an oil inlet, a first working port and an oil return port, and the oil inlet of the reversing valve 4 is communicated with the oil outlet of the second quantitative pump 12, and the direction is reversed. The first working port of the valve 4 communicates with the oil outlet line 31 , and the oil return port of the reversing valve 4 communicates with the oil return line 32 . The reversing valve 4 changes the flow direction of the oil in the reversing valve 4 in response to the oil pressure of the oil outlet line 31 . Specifically, when the oil pressure of the oil outlet pipe 31 is lower than the set pressure, the oil inlet of the reversing valve 4 is connected to the first working port; when the oil pressure of the oil outlet pipe 31 reaches the set pressure, The oil inlet and the oil return port of the reversing valve 4 are connected.

In the sequence control loop for the servo motor to drive the quantitative pump in this embodiment, the servo motor 1 drives the double pump as the power source, and when the actuator starts, the first quantitative pump 11 and the second quantitative pump 12 are merged. For oil supply, the servo motor 1 runs at a high speed to meet the large flow required when the actuator is started, and in normal working conditions, the reversing valve 4 changes direction in response to the oil pressure of the oil outlet pipeline 31, so that the second quantitative pump 12 Unloading, only the first quantitative pump 11 supplies oil, and the servo motor 1 runs at low speed to meet the small flow required for the normal operation of the actuator, which can effectively reduce the power loss and improve the energy conversion efficiency. Compared with the existing The power source in the technology is more energy-saving, and can also reduce the heat generation of the hydraulic system and prolong the service life of the hydraulic system.

In the hydraulic station of the rolling mill, the actuator is mainly a depressing oil cylinder, and the difference between the large flow required for the actuator to start and the small flow required for normal working conditions is not large. Therefore, in order to better adapt to the rolling mill’s actuator Power demand, the first quantitative pump 11 is a large-flow low-pressure pump, and the second quantitative pump 12 is a small-flow high-pressure pump. Under normal working conditions, the power source continues to supply oil through a large-flow low-pressure pump, so that the power source can support more types of actions of the actuators, and the power source has a wider application range.

As shown in FIG. 1 , in order to accelerate the unloading of the second quantitative pump 12, the reversing valve 4 also has a second working port that communicates with the oil return line 32. When the oil pressure of the oil outlet line 31 reaches the set pressure , the oil inlet of the reversing valve 4 is also connected to the second working port. A first check valve 71 is provided between the second working port of the reversing valve 4 and the oil return line 32, and the inlet of the first check valve 71 is communicated with the second working port of the reversing valve 4, and the first check valve 71 is connected to the second working port of the reversing valve 4. The outlet to the valve 71 communicates with the oil return line 32 .

As shown in FIG. 1 , the sequence valve 5 is used to control the reversing valve 4 to change the flow direction of the internal hydraulic oil in response to the oil pressure of the oil outlet pipeline 31 . The sequence valve 5 has an oil inlet and an oil outlet, wherein the oil inlet of the sequence valve 5 is communicated with the oil outlet pipeline 31, and the opening pressure of the sequence valve 5 is the aforementioned set pressure; the reversing valve 4 has a control port One of the control ports of the hydraulic reversing valve is connected with the oil outlet of the sequence valve 5, and the other is connected with the oil discharge pipeline 33. In this embodiment, the sequence valve 5 is used to control the reversing of the hydraulic reversing valve. Compared with the electromagnetic reversing valve that needs to be used in conjunction with the control element, it can not only realize self-control, but also make the transmission of control signals more reliable, and the operation is not easy to make mistakes. It can also delay the impact of the hydraulic oil flowing out of the small-flow high-pressure pump when it changes direction in the reversing valve, so that the control system runs more stably.

As shown in FIG. 1 , in order to delay the reset action of the hydraulic reversing valve, the oil discharge pipeline 33 is provided with a damper 6 for adjusting the resetting time of the hydraulic reversing valve. The arrangement of the damper 6 can protect the control circuit and the reversing valve 4 .

As shown in FIG. 1 , in order to enable the hydraulic oil of the double pump to enter the oil outlet pipe 31 quickly, the oil outlet pipe 31 is provided with a second one-way valve 72 , and the branch pipe 34 is provided with a second check valve 72 located behind the reversing valve 4 Three one-way valves 73 . In this embodiment, the inlet of the third one-way valve 73 is communicated with the first working port of the reversing valve 4, and the outlet of the third one-way valve 73 and the oil outlet of the first quantitative pump 11 are both connected to the second one-way valve The inlet of the valve 72 is connected, so that the hydraulic oil from the second quantitative pump 12 flows out through the third one-way valve 73 and merges with the hydraulic oil from the first quantitative pump 11 to enter the second one-way valve 72 .

As shown in FIG. 1 , in order to protect the control circuit, a first relief valve 81 and a second relief valve 82 are also included, and both the first relief valve 81 and the second relief valve 82 have an oil inlet and an oil outlet. The oil inlet of the first relief valve 81 is communicated with the oil outlet pipeline 31 , and the oil outlet of the first relief valve 81 is communicated with the oil return pipeline 32 , so that the first relief valve 81 is used as the set oil outlet pipeline 31 oil pressure relief valve. The oil inlet of the second relief valve 81 is communicated with the branch line 34 , and the oil outlet of the second relief valve 82 is communicated with the oil return line 32 , so that the second relief valve 82 is used as a regulator for adjusting the oil pressure of the branch line 34 . safety valve.

As shown in FIG. 1 , in order to detect the pressure of the hydraulic oil, the oil outlet pipeline 31 is provided with a first pressure gauge 91 , and the branch line 34 is provided with a second pressure gauge 92 .

As shown in Figure 1, the working principle of the sequential control loop for the servo motor to drive the quantitative pump in this embodiment is:

When the oil pressure of the oil outlet pipeline 31 is lower than the opening pressure of the sequence valve 5, the valve port of the sequence valve 5 is closed, the oil inlet and the oil outlet of the hydraulic reversing valve are connected, and the second quantitative pump 12 is connected to the first quantitative The pump 11 supplies oil at the same time, and the servo motor 1 runs at a high speed to meet the large flow required when the actuator is started; when the oil pressure of the oil outlet pipeline 31 rises to the opening pressure of the sequence valve 5, the valve port of the sequence valve 5 is opened, and the hydraulic The oil inlet of the control port of the dynamic reversing valve makes the oil inlet and oil return port of the hydraulic reversing valve conduct, the second quantitative pump 12 is unloaded, only the first quantitative pump 11 supplies oil, and the servo motor 1 runs at a low speed to To meet the small flow required for the normal operation of the actuator, the pressure of the oil outlet pipeline 31 continues to rise until the set pressure of the first relief valve 81. During this process, the sequence valve 5 keeps the valve port open and the hydraulic reversing valve keeps Reversing state; when the oil pressure of the oil outlet pipeline 31 is reduced to the opening pressure of the sequence valve 5 due to the large flow action and other working conditions, the valve port of the sequence valve 5 is closed again, and the control port of the hydraulic reversing valve no longer enters. oil, and the remaining oil flows into the oil discharge pipeline 33 through the control port of the hydraulic reversing valve, so that the hydraulic reversing valve is reset, and the oil inlet and outlet of the hydraulic reversing valve are connected again, so that the second quantitative pump 12 and the first metering pump 11 are again supplied with oil at the same time.

Claims (10)

1. A sequential control loop for a servo motor driven fixed displacement pump, characterized by: the oil return device comprises an oil outlet pipeline (31), an oil return pipeline (32) and a dual pump driven by a servo motor (2), wherein the dual pump comprises a first quantitative pump (11) and a second quantitative pump (12) which are coaxially arranged, the oil outlet of the first quantitative pump (11) is communicated with the oil outlet pipeline (31), and the oil outlet of the second quantitative pump (12) is communicated with the oil outlet pipeline (31) through a branch (34);

be equipped with reversing valve (4) that have oil inlet, first working opening and oil return opening on branch road (34), the oil inlet of reversing valve (4) with the oil-out intercommunication of second constant displacement pump (12), the first working opening of reversing valve (4) with go out oil pipe way (31) intercommunication, the oil return opening of reversing valve (4) with oil return pipeline (32) intercommunication, the oil pressure of going out oil pipe way (31) is less than under the state of set pressure, the oil inlet and the first working opening of reversing valve (4) switch on, the oil pressure of going out oil pipe way (31) reaches under the state of set pressure, the oil inlet and the oil return opening of reversing valve (4) switch on.

2. A sequential control loop for a servo motor driven fixed displacement pump according to claim 1, wherein: the first fixed displacement pump (11) is a high-flow low-pressure pump, and the second fixed displacement pump (12) is a low-flow high-pressure pump.

3. A sequential control loop for a servo motor driven fixed displacement pump according to claims 1-2, wherein: the hydraulic control system is characterized by further comprising an oil unloading pipeline (33) and a sequence valve (5) used for controlling the reversing valve (4) to change the flowing state of hydraulic oil in the reversing valve (4), wherein the sequence valve (5) is provided with an oil inlet and an oil outlet, the oil inlet of the sequence valve (5) is communicated with the oil outlet pipeline (31), and the opening pressure of the sequence valve (5) is the set pressure; the reversing valve (4) is a hydraulic reversing valve with a control port, one path of the control port of the hydraulic reversing valve is communicated with an oil outlet of the sequence valve (5), and the other path of the control port of the hydraulic reversing valve is communicated with the oil discharging pipeline (33).

4. A sequential control loop for a servo motor driven fixed displacement pump according to claim 3, wherein: and a damper (6) for adjusting the reset time of the hydraulic reversing valve is arranged between the control port of the hydraulic reversing valve and the oil unloading pipeline (33) or on the oil unloading pipeline (33).

5. A sequential control loop for a servo motor driven fixed displacement pump according to claim 1, wherein: the reversing valve (4) is also provided with a second working port communicated with the oil return pipeline (32), and an oil inlet of the reversing valve (4) is also communicated with the second working port when the oil pressure of the oil outlet pipeline (31) reaches a set pressure.

6. A sequential control loop for a servo motor driven fixed displacement pump according to claim 5, wherein: a first one-way valve (71) is arranged between a second working port of the reversing valve (4) and the oil return pipeline (32), an inlet of the first one-way valve (71) is communicated with the second working port of the reversing valve (4), and an outlet of the first one-way valve (71) is communicated with the oil return pipeline (32).

7. A sequential control loop for a servo motor driven fixed displacement pump according to claim 1 or 2 or 4 or 5 or 6, wherein: the oil outlet pipeline (31) is provided with a second one-way valve (72), the branch (34) is provided with a third one-way valve (73) located behind the reversing valve (4), an inlet of the third one-way valve (73) is communicated with a first working port of the reversing valve (4), and an outlet of the third one-way valve (73) and an oil outlet of the first dosing pump (11) are communicated with an inlet of the second one-way valve (72).

8. A sequential control loop for a servo motor driven fixed displacement pump according to claim 1 or 2 or 4 or 5 or 6, wherein: the oil return device is characterized by further comprising a first overflow valve (81) with an oil inlet and an oil outlet, the oil inlet of the first overflow valve (81) is communicated with the oil outlet pipeline (31), and the oil outlet of the first overflow valve (81) is communicated with the oil return pipeline (32).

9. A sequential control loop for a servo motor driven fixed displacement pump according to claim 8, wherein: the oil return device is characterized by further comprising a second overflow valve (82) with an oil inlet and an oil outlet, the oil inlet of the second overflow valve (82) is communicated with the branch circuit (34), and the oil outlet of the second overflow valve (82) is communicated with the oil return pipeline (32).

10. A sequential control loop for a servo motor driven fixed displacement pump according to claim 1 or 2 or 4 or 5 or 6, wherein: and a first pressure gauge (91) is arranged on the oil outlet pipeline (31), and a second pressure gauge (92) is arranged on the branch (34).

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