CN211738170U

CN211738170U - High dynamic control system of solenoid valve

Info

Publication number: CN211738170U
Application number: CN202020025868.8U
Authority: CN
Inventors: 钟麒; 孙造诣; 王军; 何贤剑; 汪谢乐; 李研彪; 陈波; 孙鹏
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2020-01-07
Filing date: 2020-01-07
Publication date: 2020-10-23
Anticipated expiration: 2030-01-07

Abstract

The utility model discloses a high dynamic control system of solenoid valve. The system comprises a preloading voltage source, a high voltage source, a voltage stabilizing source, a negative voltage source, a zero voltage source, a high-speed change-over switch, a current detector, an electromagnetic valve, a pressure sensing system and a controller; by loading the voltage in advance before the expected opening and closing time of the electromagnetic valve, the current of the coil is kept in a state slightly smaller than the opening current (opening stage) or in a state slightly larger than the closing current (closing stage), so that the opening and closing lag time is greatly reduced. In the starting stage, a high-voltage source is adopted for excitation, so that the current rises rapidly, and the movement time in the starting stage is reduced; in the closing stage, the current is rapidly reduced to 0 by adopting the excitation of a negative voltage source, and the movement time of the closing stage is reduced.

Description

High dynamic control system of solenoid valve

Technical Field

The utility model relates to a solenoid valve control field, concretely relates to high dynamic control system of solenoid valve.

Background

In the driving of the electromagnetic valve, the ampere-turns and the working air gap have the largest influence on the electromagnetic force of the electromagnet. Ampere-turns is the product of the number of turns of the coil and the current in the single coil. In the case where the magnetic flux is not saturated, the larger the current, the larger the electromagnetic force; the smaller the working air gap, the greater the electromagnetic force. Since the solenoid valve is usually opened when the working air gap in the electromagnet is largest, and closed when the working air gap in the electromagnet is smallest, the opening current is larger than the closing current.

At present, the solenoid valves in the hydraulic field are mostly controlled by single voltage, namely, at the expected opening time, the driving voltage is switched on, so that the current of a solenoid valve coil is increased, and the solenoid valves are opened until the electromagnetic force is enough to overcome various resistances; the electromagnetic valve is opened and lagged, the coil keeps a voltage excitation state, so that the current of the coil is continuously increased until the maximum current value which can be reached by the current driving voltage is reached until the expected closing moment is reached, at the moment, the driving voltage is disconnected, the current of the coil is naturally reduced under the condition of no voltage excitation, the electromagnetic force is reduced along with the current of the coil until the electromagnetic force is insufficient to overcome the restoring force, and at the moment, the valve core of the electromagnetic valve starts to perform reset motion. The method is simple to control, the frequency of the electromagnetic valve switch is realized by adjusting the frequency of the driving voltage, and the opening and closing time of the electromagnetic valve in a signal period is controlled by adjusting the duty ratio of the driving voltage.

However, the control method has some disadvantages, which are mainly expressed in that: when the drive voltage is too small, the time required for the current to increase to open the solenoid is long, and therefore the opening lag time is long; when the driving voltage is too large, the current continues to increase after the solenoid valve is opened until the maximum value that the current can reach, so that at the expected closing time of the solenoid valve, the initial value of the current is large, and the time required for the current to drop to close the solenoid valve is long under the natural state of zero-voltage driving of the coil, so that the closing lag time is long. Therefore, the single-voltage driving method cannot simultaneously take account of the dynamic characteristics of the two stages of opening and closing the solenoid valve. Furthermore, in the method, when the valve is opened, the driving voltage is still high in order to maintain the open state, which easily causes the current in the coil to continuously rise to the maximum value, thereby causing the coil to generate heat and reducing the service life of the solenoid valve.

Disclosure of Invention

In order to solve the difficulty, the utility model provides a high dynamic control system of solenoid valve and method.

The utility model discloses a high dynamic control system of solenoid valve at first, it includes preloading voltage source, high voltage source, voltage stabilizing source, negative voltage source, zero voltage source, high-speed change over switch, current detector, solenoid valve, pressure sensing system and controller;

the high-speed change-over switch is provided with six contact heads, wherein a first contact head, a second contact head, a third contact head, a fourth contact head and a fifth contact head are respectively connected with a preloading voltage source, a high voltage source, a stable voltage source, a negative voltage source and a zero voltage source; the sixth contact is connected with the solenoid valve coil through the current detector; the output port of the controller is connected with the high-speed selector switch and can control the connection state of the sixth contact and the rest contacts; the pressure sensing system is connected with each working port of the electromagnetic valve and is used for obtaining the pressure state of each working port of the electromagnetic valve; the controller is connected with the pressure sensing system and comprises a control signal generating unit.

As the preferred embodiment of the present invention, the control signal generated by the control signal generating unit is a square wave signal, and the duty ratio of the square wave signal is the ratio of the target opening time to the cycle time of the solenoid valve. The control signal is generated by an operator through programming of a control signal generating unit inside the controller, and the control signal participates in the operation inside the controller. The controller acquires the duty ratio, the frequency, the rising edge moment and the falling edge moment of the control signal generated by the control signal generating unit in real time. When the control signal is changed, the controller can also know the duty ratio, the frequency, the rising edge time and the falling edge time of the changed control signal, so that the controller can know when the rising edge of the control signal of the next period comes.

The utility model has the advantages that:

1) the pressure of each working port of the electromagnetic valve can be obtained through a pressure sensing system and fed back to an arithmetic unit, and the arithmetic unit automatically calculates opening current and closing current according to data tested in the early stage of the electromagnetic valve;

2) the pressure sensing system and the controller are matched for use, and even if the working condition of the electromagnetic valve changes in the working process, the controller can also intelligently adjust according to the pressure value read by the pressure sensing system, so that the electromagnetic valve has the self-adaptive capacity to the working condition;

3) by loading the response voltage in advance before the expected opening and closing time of the electromagnetic valve, the current of the coil is kept in a state slightly smaller than the opening current (opening stage) or in a state slightly larger than the closing current (closing stage), so that the opening and closing lag time is greatly reduced.

4) The high voltage source connection time of the utility model is equal to the time required by the electromagnetic valve to be excited to be completely opened by adopting the same high voltage source under the 0 current state; the method has the advantages that: the dynamic characteristic of the opening phase can be further improved because if the dynamic characteristic of the solenoid valve is slow, but the electromagnetic dynamic characteristic of the electromagnet is good, then there will be a rapid rise of the current to the opening current, while the electromagnet is still moving, i.e. not fully opened, if at this time the high voltage source is switched to a regulated voltage source, the dynamic characteristic of the opening phase will be reduced.

5) The utility model discloses under the state of intercommunication negative voltage source, make the negative voltage continue to encourage, reduce to 0 until the electric current. This method is different from the prior art scheme that only uses a negative voltage source to reduce the current to less than the critical off current. The dynamic characteristic of the electromagnetic valve is weak, the electromagnetic dynamic characteristic of the electromagnet is good, and the method in the prior art can have a phenomenon that the current is reduced to the closing current, but the electromagnet is still in the closing motion stage and the motion speed is slow. If the negative voltage is switched to zero at this time, the dynamic characteristic of the closing movement of the electromagnet cannot be further improved. Therefore, the current of the electromagnet is directly reduced to zero, and the dynamic characteristic of the closing stage of the electromagnet can be improved to the maximum extent.

Drawings

Fig. 1 is a schematic structural diagram of the high dynamic control system of the electromagnetic valve of the present invention;

fig. 2 is a control signal and current curve diagram of the present invention.

Fig. 3 shows the opening and closing characteristics (opening) of the solenoid valve of the high dynamic control system of the solenoid valve.

Fig. 4 shows the solenoid valve opening and closing characteristics (closing) of the high dynamic control system of the solenoid valve.

Detailed Description

The invention is further described with reference to the drawings and the specific embodiments.

As shown in fig. 1, the high dynamic control system for the solenoid valve of the present embodiment includes a preload voltage source 1, a high voltage source 2, a steady voltage source 3, a negative voltage source 4, a zero voltage source 5, a high speed switch 6, a current detector 7, a solenoid valve 8, a pressure sensing system 9, a controller 10, and a control signal 11. The controller 10 includes a control signal generating unit, and the control signal 11 is generated by an operator through programming of the control signal generating unit inside the controller, and the control signal participates in the operation inside the controller. The controller 10 acquires the duty ratio, the frequency, the rising edge time and the falling edge time of the control signal generated by the control signal generating unit in real time.

The high-speed change-over switch is internally provided with 6 contact heads which are respectively 6-1,6-2,6-3,6-4,6-5 and 6-6, wherein 6-1 to 6-5 are respectively connected with a preloading voltage source 1, a high voltage source 2, a steady voltage source 3, a negative voltage source 4 and a zero voltage source 5, and 6-6 are connected with a current detector. The controller 10 can control the connection state of the contacts 6-6 with the remaining 5 contacts. The pressure sensing system 9 is connected with each working port of the electromagnetic valve 8 and is used for obtaining the pressure state of each working port of the electromagnetic valve. The controller 10 is connected to the pressure sensing system 9. The control signal 11 is input by an operator, and represents the on-off state of the solenoid valve that the operator expects to obtain, and for more clear description of the present scheme, the control signal is drawn outside the controller (mainly used for representing the action relationship of the control signal on the controller), and actually the control signal is generated by the controller itself (generated by a control signal generating unit in the controller).

Before the system is used, electrical parameters such as resistance and inductance of a solenoid valve coil are obtained by a static test method. Obtaining current required by opening of the electromagnetic valve under the current working condition (the current working condition refers to the current oil inlet pressure PP and the control port pressure PA) by a static test method, and fitting by software through earlier-stage test data to obtain a function expression of an electromagnetic valve opening current IO, an electromagnetic valve closing current IC and the current working condition, wherein the current is defined as the opening current; the current required for shutdown at the present operating condition is defined as the shutdown current.

The voltage value of the preloading voltage source 1 is less than 5-10% of the product of the resistance of the solenoid valve coil and the opening current, and the voltage value of the steady voltage source 3 is greater than 5-10% of the product of the resistance of the solenoid valve coil and the closing current. The specific values of preload voltage source 1 and regulated voltage source 3 are freely settable by the operator.

As shown in fig. 2, the method for realizing the high dynamic characteristic of the solenoid valve by the system comprises the following steps: the single working period of the electromagnetic valve is subdivided into 5 stages, and the stages are respectively represented as (r) -fifth from front to back according to the time sequence.

When the system is started, the controller calculates the time required by the coil current to rise to the preloading current according to the current, the coil resistance and the inductance, and on the basis of the time, the time is prolonged by 5-10 percent, namely the duration of the first stage; the controller connects 6-6 and 6-1 in advance before the rising edge of the control signal comes according to the calculation result, and enters a stage I, and the stage I is accurately calculated by the controller, so that the current of the coil can be stabilized in a state slightly smaller than the starting current.

When the rising edge of the control signal comes, which represents that an operator wants the solenoid valve to be opened, the controller connects 6-6 with 6-2, the current of the coil can rapidly rise to the opening current under the excitation of the high voltage source, at the moment, the valve core of the solenoid valve is opened and moved to enter the opening stage, in order to ensure the dynamic characteristic of the opening stage, the connection between 6-6 and 6-2 is continuously kept until the duration time delta t (namely the high voltage excitation time of the utility model) is the time when the current state of the solenoid valve is 0, the same high voltage source is adopted to continuously load until the valve is completely opened. Adopt the utility model discloses the duration deltat that selects certainly can ensure that the solenoid valve is opened completely after this duration under the condition of preloading current. Since the preload current of the invention is already increased compared to the situation when the starting current is 0, it is then certain that the full opening is possible in the case of the preload current if the full opening is possible over this time at 0 current.

The controller then connects 6-6 with 6-3, since the value of the regulated voltage source is slightly larger than the product of the coil resistance and the closing current, the current will gradually decrease and finally stabilize in a state slightly larger than the closing current, so as to keep the solenoid valve open. When the control signal falling edge comes, this time represents that the operator hopes the electromagnetic valve to close, the controller connects 6-6 with 6-4, because when stage (iii) finishes, the electric current has already been maintained at a value slightly greater than closing current, therefore under the excitation of the negative voltage, the electric current will reduce to closing current rapidly, the valve core begins to move at this moment, reset, therefore, the lag time of the closing stage is shorter, the negative voltage continues to excite, until the electric current reduces to 0, because the electric current is 0, the electro-magnet does not produce the electromagnetic force, therefore, the restoring force that the valve core obtains is the biggest, can accelerate the valve core to return to the movement to the greatest extent, improve the dynamic characteristic of the closing stage. When the current reaches 0, the controller connects 6-6 with 6-5, and the coil current keeps the 0 current state under the excitation of 0 voltage until the next (phi) stage arrives. The arrival time of the first stage is still determined according to the arrival time of the rising edge of the next control signal and the time required for the current to rise to a state slightly less than the starting current.

According to the method, the voltage source 1 is preloaded, so that the current is already in a state slightly smaller than the opening current before the opening instruction comes, therefore, when the rising edge (opening instruction) of a control signal comes, the electromagnetic valve is excited by high voltage, the current can rise to the opening current in the fastest time, and the opening lag time is reduced. And after the current reaches the opening current, the high voltage continues to be excited until the connection time is equal to the time required by the electromagnetic valve to be completely opened by adopting the high voltage source under the 0 current state, so that the electromagnetic force is continuously increased in the opening motion process of the electromagnetic valve, and the opening motion process is accelerated. According to the method, the current is already in a state slightly larger than the closing current before a closing command comes through the voltage stabilizing source, so that when a control signal falling edge (closing command) comes, the electromagnetic valve is excited by adopting negative voltage, the current can be reduced to the closing current in the fastest time, and the closing lag time is reduced. And after the current reaches the closing current, the negative voltage is continuously excited until the current is reduced to 0, so that the electromagnetic force is continuously reduced in the opening motion process of the electromagnetic valve, the resultant force of the valve core in the recovery process is increased, and the closing motion process of the electromagnetic valve is accelerated.

The opening current and the closing current of the electromagnetic valve are influenced by the pressure of each working port, so that the opening current and the closing current of the controlled electromagnetic valve under different pressures of each working port can be obtained in advance, a database is established, then the controller obtains the current pressure of each working port of the electromagnetic valve through the pressure sensing system, obtains the opening current and the closing current under the current working condition according to the data in the database, and is used for updating the numerical values of the pre-loading voltage source 1 and the voltage stabilizing source 3 in real time when the system works.

As shown in fig. 3-4, in one embodiment of the present invention, the preload voltage source is set to 15V, high voltage source 24V, regulated voltage source 10V, and negative voltage source-24V. The on-off time of the control signal is 5ms and 30ms respectively. Since the coil is energized in advance with a voltage of 15V in the opening preload stage of the high-speed switch valve, as shown in fig. 3, the coil current is already stabilized at 1.5A when the opening command signal arrives. The utility model discloses the initial current of opening the stage has been optimized to the method, and high-speed switch valve opening lag time shortens to 0.6 ms. When the coil current reaches the opening trigger current value after the high-speed switch valve is opened, the controller switches on the closing preloading voltage of 10V to continuously excite the high-speed switch valve according to the voltage switching mechanism shown in figure 2. Therefore, the coil current gradually decreases and stabilizes at around 1A, providing a small initial current for the closing movement of the high-speed opening and closing valve. When the closing command signal arrives, the controller switches to a closing voltage of-24V for excitation, and as shown in FIG. 4, under the unloading action of the negative voltage, the current can be rapidly reduced to a 0A current state, and the closing delay process of the high-speed switch valve is shortened.

Claims

1. A high dynamic control system of an electromagnetic valve is characterized by comprising a preloading voltage source (1), a high voltage source (2), a voltage stabilizing source (3), a negative voltage source (4), a zero voltage source (5), a high-speed switch (6), a current detector (7), an electromagnetic valve (8), a pressure sensing system (9) and a controller (10);

the high-speed switch (6) is provided with six contact heads, wherein a first contact head (6-1), a second contact head (6-2), a third contact head (6-3), a fourth contact head (6-4) and a fifth contact head (6-5) are respectively connected with a preloading voltage source (1), a high voltage source (2), a voltage stabilizing source (3), a negative voltage source (4) and a zero voltage source (5); the sixth contact head (6-6) is connected with the solenoid valve coil through a current detector (7); the output port of the controller (10) is connected with the high-speed selector switch (6) and can control the connection state of the sixth contact (6-6) and the rest contacts; the pressure sensing system (9) is connected with each working port of the electromagnetic valve (8) and is used for obtaining the pressure state of each working port of the electromagnetic valve; the controller (10) is connected with the pressure sensing system (9), and the controller (10) comprises a control signal generating unit.

2. The high-dynamic control system for the electromagnetic valve according to claim 1, wherein the control signal generated by the control signal generating unit is a square wave signal, and the duty ratio of the square wave signal is the target opening time and the cycle time ratio of the electromagnetic valve.

3. The high-dynamic control system of the electromagnetic valve according to claim 1, characterized in that the controller (10) obtains the duty ratio, the frequency, the rising edge time and the falling edge time of the control signal generated by the control signal generating unit in real time.