A solenoid valve high dynamic control system and method thereof

Abstract

The present invention discloses a high-dynamic control system for a solenoid valve and a method thereof. The system includes a preload voltage source, a high voltage source, a steady voltage source, a negative voltage source, a zero voltage source, a high-speed switching switch, a current detector, a solenoid valve, a pressure sensing system and a controller; by loading the voltage in advance before the expected opening and closing time of the solenoid valve, the coil current is kept in a state slightly less than the opening current (opening stage), or kept in a state slightly greater than the closing current (closing stage), thereby greatly reducing the opening and closing lag time. In the opening stage, a high voltage source is used for excitation, so that the current rises rapidly, reducing the movement time of the opening stage; in the closing stage, a negative voltage source is used for excitation, so that the current drops rapidly to 0, reducing the movement time of the closing stage.

Description

Technical Field

[0001] The present invention relates to the field of solenoid valve control, and in particular to a solenoid valve high-dynamic control system and a method thereof. Background Art

[0002] In the driving of the solenoid valve, the ampere-turns and the working air gap have the greatest influence on the electromagnetic force of the electromagnet. The ampere-turns are the product of the number of coil turns and the current in a single-turn coil. When the magnetic flux is not saturated, the greater the current, the greater the electromagnetic force; the smaller the working air gap, the greater the electromagnetic force. Since the solenoid valve is often opened when the working air gap in the electromagnet is the largest, and is often closed when the working air gap in the electromagnet is the smallest, the opening current is larger than the closing current.

[0003] At present, most solenoid valves in the hydraulic field adopt single voltage control, that is, at the expected opening time, the driving voltage is turned on to increase the current of the solenoid valve coil until the electromagnetic force is sufficient to overcome various resistances, and the solenoid valve opens; the solenoid valve opens with a lag, and the coil continues to maintain the voltage excitation state, so the coil current continues to increase until the maximum current value that the current driving voltage can reach, until the expected closing time arrives, at which time the driving voltage is disconnected, and the coil current naturally decreases without voltage excitation, and the electromagnetic force also decreases until the electromagnetic force is insufficient to overcome the restoring force, at which time the solenoid valve core begins to reset. This method is simple to control, and the frequency of the solenoid valve switch is achieved by adjusting the frequency of the driving voltage, and the opening and closing time of the solenoid valve within a signal cycle is controlled by adjusting the duty cycle of the driving voltage.

[0004] However, this control method has some shortcomings, mainly manifested in: when the driving voltage is too small, it takes a long time for the current to increase to open the solenoid valve, so 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 current reaches the maximum value that can be reached. Therefore, at the expected closing moment of the solenoid valve, the initial current value is large, and the coil is in the natural state of zero voltage drive. It takes a long time for the current to drop to close the solenoid valve, so the closing lag time is long. Therefore, the single voltage drive method cannot take into account the dynamic characteristics of the two stages of opening and closing of the solenoid valve at the same time. Moreover, in this method, when the valve is already opened, in order to maintain the open state, the driving voltage is still at a high level, which easily causes the current in the coil to continue to rise to the maximum value that can be reached, thereby causing the coil to heat up and reducing the life of the solenoid valve. Summary of the invention

[0005] In order to solve the above difficulties, the present invention proposes a high-dynamic control system and method for a solenoid valve.

[0006] The present invention firstly discloses a high dynamic control system for a solenoid valve, which comprises a preload voltage source, a high voltage source, a stable voltage source, a negative voltage source, a zero voltage source, a high-speed switching switch, a current detector, a solenoid valve, a pressure sensing system and a controller;

[0007] The high-speed switching switch has six contact heads, wherein the first contact head, the second contact head, the third contact head, the fourth contact head, and the fifth contact head are respectively connected to a preload voltage source, a high voltage source, a stable voltage source, a negative voltage source, and a zero voltage source; the sixth contact head is connected to the solenoid valve coil through a current detector; the output port of the controller is connected to the high-speed switching switch and can control the connection state of the sixth contact head and the remaining contact heads; the pressure sensing system is connected to each working port of the solenoid valve to obtain the pressure state of each working port of the solenoid valve; the controller is connected to the pressure sensing system, and the controller includes a control signal generating unit.

[0008] As a preferred embodiment of the present invention, the control signal generated by the control signal generating unit is a square wave signal, and the duty cycle of the square wave signal is the ratio of the target opening time of the solenoid valve to the cycle time. The control signal is generated by the operator through the control signal generating unit inside the controller, and the control signal participates in the internal operation of the controller. The controller obtains the duty cycle, frequency, rising edge time and falling edge time of the control signal generated by the control signal generating unit in real time. When the control signal changes, the controller can also know the duty cycle, frequency, rising edge time and falling edge time of the changed control signal, so as to know when the rising edge of the control signal of the next cycle will arrive.

[0009] The present invention also discloses a high-dynamic control method for a solenoid valve based on the system, comprising the following steps:

[0010] The control signal generating unit generates a control signal. Before the rising edge of the control signal arrives, the controller calculates the duration of the preloading stage according to the current coil current state and the electrical parameters of the coil. According to the duration of the preloading stage, the controller connects the sixth contact head with the first contact head in advance to enter the preloading stage. After the preloading stage, the coil current is stabilized at a preloading current state that is less than the set ratio of the start current.

[0011] When the rising edge of the control signal arrives, the controller connects the sixth contact head with the second contact head. Under the excitation of the high voltage source, the current of the coil rises rapidly. Since the current has been stabilized at a state slightly less than the opening current before the rising edge of the control signal arrives, the current will rise to the opening current in a short time with the excitation of the high voltage source. At this time, the solenoid valve core opens and moves to enter the opening stage. The second contact head and the sixth contact head continue to be connected until the connection time is equal to the time required for the solenoid valve to be fully opened by the excitation of the high voltage source under the state of 0 current;

[0012] After the set time is reached, the controller connects the sixth contact head with the third contact head, the current gradually decreases, and finally stabilizes at a maintaining current state that is greater than the set proportion of the closing current to keep the solenoid valve open;

[0013] When the falling edge of the control signal arrives, the controller connects the sixth contact head with the fourth contact head. Under the excitation of the negative voltage source, the coil current quickly decreases to the closing current. At this time, the valve core starts to move and resets. The negative voltage continues to excite until the current decreases to 0.

[0014] When the current reaches 0, the controller connects the sixth contactor to the fifth contactor, and the coil current continues to maintain a zero current state under the excitation of the zero voltage source until the next preloading stage arrives.

[0015] As a preferred embodiment of the present invention, the voltage value of the preloaded voltage source is slightly smaller than the product of the solenoid valve coil resistance and the opening current, and in the preferred embodiment of the present invention, it is smaller than 5%-10% of the product of the solenoid valve coil resistance and the opening current; the voltage value of the steady voltage source is slightly larger than the product of the solenoid valve coil resistance and the closing current, and in the preferred embodiment of the present invention, it is larger than 5%-10% of the product of the solenoid valve coil resistance and the closing current.

[0016] As a preferred embodiment of the present invention, the calculation process of the duration required for the preloading stage is as follows: the controller calculates the time required for the coil current to rise to the preloading current based on the current solenoid valve current, coil resistance and inductance, and based on this time, extends the set time (preferably, based on this time, extends the duration by 5%-10%), which is the duration of the preloading stage.

[0017] The present invention has the following beneficial effects:

[0018] 1) The pressure of each working port of the solenoid valve can be obtained through the pressure sensing system and fed back to the operator. The operator automatically calculates the opening current and closing current based on the data of the previous test of the solenoid valve;

[0019] 2) The pressure sensing system and the controller are used together. Even if the working condition of the solenoid valve changes during operation, the controller can make intelligent adjustments based on the pressure value read by the pressure sensing system, so that the solenoid valve has the ability to adapt to the working condition;

[0020] 3) By loading the response voltage in advance before the expected opening and closing time of the solenoid valve, the coil current is kept at a state slightly smaller than the opening current (opening stage), or kept at a state slightly larger than the closing current (closing stage), thereby greatly reducing the opening and closing lag time.

[0021] 4) The connection time of the high voltage source of the present invention is equal to the time required for the solenoid valve to be fully opened by using the same high voltage source under the 0 current state; the advantage of this approach is that the dynamic characteristics of the opening stage can be further improved. The reason is that if the dynamic characteristics of the solenoid valve are very slow, but the electromagnetic dynamic characteristics of the electromagnet are very good, then the current will quickly rise to the opening current, but the electromagnet is still moving, that is, it is not fully opened. If the high voltage source is switched to a stable voltage source at this time, the dynamic characteristics of the opening stage will be reduced.

[0022] 5) The present invention continues to excite the negative voltage when the negative voltage source is connected until the current is reduced to 0. This method is different from the scheme in the prior art that only uses a negative voltage source to reduce the current to less than the critical closing current. The dynamic characteristics of the solenoid valve are relatively weak, while the electromagnetic dynamic characteristics of the electromagnet are relatively good. There is a phenomenon when using the method in the prior art, that is, the current has been reduced to the closing current, but the electromagnet is still in the closing movement stage, and the movement speed is relatively slow. If the negative voltage is switched to zero voltage at this time, the dynamic characteristics of the electromagnet's closing movement cannot be further improved. Therefore, directly reducing the current of the electromagnet to zero can maximize the dynamic characteristics of the electromagnet in the closing stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the high dynamic control system of the solenoid valve of the present invention;

[0024] Figure 2 It is the control signal and current curve diagram of the present invention.

[0025] Figure 3 It is the opening and closing characteristics (opening) of the solenoid valve of the solenoid valve high dynamic control system.

[0026] Figure 4 It is the opening and closing characteristics (closed) of the solenoid valve of the solenoid valve high dynamic control system. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1As shown, the electromagnetic valve high dynamic control system of this embodiment includes a preload voltage source 1, a high voltage source 2, a regulated voltage source 3, a negative voltage source 4, a zero voltage source 5, a high-speed switching switch 6, a current detector 7, an electromagnetic valve 8, a pressure sensing system 9, a controller 10 and a control signal 11. Among them, the controller 10 includes a control signal generating unit, and the control signal 11 is generated by the operator through the control signal generating unit inside the controller, and the control signal participates in the internal operation of the controller. The controller 10 obtains the duty cycle, frequency, rising edge time and falling edge time of the control signal generated by the control signal generating unit in real time.

[0029] There are 6 contacts inside the high-speed switching switch, namely 6-1, 6-2, 6-3, 6-4, 6-5 and 6-6, of which 6-1 to 6-5 are respectively connected to the preload voltage source 1, the high voltage source 2, the steady voltage source 3, the negative voltage source 4 and the zero voltage source 5, and 6-6 is connected to the current detector. The controller 10 can control the connection state of the contact 6-6 and the other 5 contacts. The pressure sensing system 9 is connected to each working port of the solenoid valve 8 to obtain the pressure state of each working port of the solenoid valve. The controller 10 is connected to the pressure sensing system 9. The control signal 11 is input by the operator and represents the opening and closing state of the solenoid valve that the operator expects to obtain. In order to describe this scheme more clearly, the control signal is drawn outside the controller (mainly used to indicate the effect of the control signal on the controller). In fact, the control signal is generated by the controller itself (generated by the control signal generation unit in the controller).

[0030] Before using the system, the electrical parameters such as the solenoid valve coil resistance and inductance are obtained by static testing. The current required to open the solenoid valve under the current working condition (the current working condition refers to the current oil inlet pressure PP and the control port pressure PA. The function expression of the solenoid valve opening current IO, the solenoid valve closing current IC and the current working condition can be obtained by fitting the previous test data with software) is defined as the opening current; the current required to close the solenoid valve under the current working condition is defined as the closing current.

[0031] The voltage value of the preload voltage source 1 is less than 5-10% of the product of the solenoid valve coil resistance and the opening current, and the voltage value of the stabilizing voltage source 3 is greater than 5-10% of the product of the solenoid valve coil resistance and the closing current. The specific values ​​of the preload voltage source 1 and the stabilizing voltage source 3 can be freely set by the operator.

[0032] like Figure 2 As shown, the method for the system to achieve high dynamic characteristics of the solenoid valve is: subdividing a single working cycle of the solenoid valve into 5 stages, which are represented as ①-⑤ from front to back in chronological order.

[0033] When the system starts, the controller calculates the time required for the coil current to rise to the preload current based on the current, coil resistance and inductance, and extends the time by 5-10%, i.e. the duration of stage ①. Based on the calculation result, the controller connects 6-6 and 6-1 in advance before the rising edge of the control signal arrives, and enters stage ①. Since stage ① is accurately calculated by the controller, the coil current will stabilize at a state slightly smaller than the start-up current.

[0034] When the rising edge of the control signal arrives, it means that the operator wants the solenoid valve to open. The controller connects 6-6 and 6-2. Under the excitation of the high voltage source, the current of the coil will quickly rise to the opening current. At this time, the solenoid valve core opens and moves, entering the opening stage. In order to ensure the dynamic characteristics of the opening stage, 6-6 and 6-2 continue to be connected until the duration Δt (i.e., the high voltage excitation time of the present invention) is the time when the solenoid valve is in the current state of 0, and the same high voltage source is used to continuously load until the valve is fully opened. The duration Δt selected by the present invention can definitely ensure that the solenoid valve is fully opened after this duration under the condition of preloading current. Because the preloading current of the present invention has increased compared to the situation when the starting current is 0, if it can be fully opened after this time at 0 current, then it can definitely be fully opened under the condition of preloading current.

[0035] Then, the controller connects 6-6 with 6-3. Since the value of the voltage stabilizer is slightly larger than the product of the coil resistance and the closing current, the current will gradually decrease and finally stabilize at a state slightly larger than the closing current to keep the solenoid valve open. When the falling edge of the control signal arrives, it means that the operator wants the solenoid valve to close. The controller connects 6-6 with 6-4. Since the current has been maintained at a value slightly larger than the closing current at the end of stage ③, the current will quickly decrease to the closing current under the excitation of the negative voltage. At this time, the valve core begins to move and reset. Therefore, the lag time of the closing stage is short, and the negative voltage continues to excite until the current is reduced to 0. Since the electromagnet does not generate electromagnetic force when the current is 0, the valve core obtains the maximum restoring force, which can accelerate the valve core recovery movement to the greatest extent and improve the dynamic characteristics of the closing stage. When the current reaches 0, the controller connects 6-6 with 6-5. The coil current continues to maintain a 0 current state under the excitation of 0 voltage until the next stage ① arrives. The arrival time of stage ① is still determined by the arrival time of the next control signal rising edge and the time required for the current to rise to a state slightly smaller than the opening current.

[0036] The method, by preloading the voltage source 1, makes the current in a state slightly less than the opening current before the opening instruction arrives, so when the rising edge of the control signal (opening instruction) arrives, the solenoid valve adopts high voltage excitation, and the current can rise to the opening current in the fastest time, thereby reducing the opening lag time. Moreover, when the current reaches the opening current, the high voltage continues to excite until the connection time is equal to the time required for the solenoid valve to be fully opened by the high voltage source under the 0 current state, thereby continuously increasing the electromagnetic force during the opening movement of the solenoid valve and accelerating the opening movement process. The method, by using a steady voltage source, makes the current in a state slightly greater than the closing current before the closing instruction arrives, so when the falling edge of the control signal (closing instruction) arrives, the solenoid valve adopts negative voltage excitation, and the current can drop to the closing current in the fastest time, thereby reducing the closing lag time. Moreover, when the current reaches the closing current, the negative voltage continues to excite until the current drops to 0, thereby continuously reducing the electromagnetic force during the opening movement of the solenoid valve, increasing the combined force of the valve core recovery process, and accelerating the closing movement process of the solenoid valve.

[0037] Since the opening current and closing current of the solenoid valve are affected by the pressure of its various working ports, the opening current and closing current of the controlled solenoid valve under different pressures of each working port can be obtained in advance, and a database can be established. Then the controller obtains the current pressure of each working port of the solenoid valve through the pressure sensing system, and obtains the opening current and closing current under the current working conditions based on the information in the database. When the system is working, it is used to update the values ​​of the preload voltage source 1 and the steady voltage source 3 in real time.

[0038] like Figure 3-4 As shown, in a specific embodiment of the present invention, the preload voltage source is set to 15V, the high voltage source is 24V, the steady voltage source is 10V, and the negative voltage source is -24V. The control signal opening and closing times are 5ms and 30ms respectively. Since the 15V voltage is used to excite the coil in advance during the preload stage of the high-speed switch valve opening, as shown in FIG. Figure 3 As shown, the coil current is already stable at 1.5A when the opening command signal arrives. The method of the present invention optimizes the initial current in the opening stage, and the opening lag time of the high-speed switch valve is shortened to 0.6ms. When the coil current reaches the opening trigger current value after the high-speed switch valve is opened, the controller Figure 2 The voltage switching mechanism shown in the figure, the 10V closing preload voltage is turned on to continue to excite the high-speed switch valve. Therefore, the coil current gradually decreases and stabilizes at about 1A, providing a small initial current for the closing movement of the high-speed switch valve. When the closing command signal arrives, the controller switches to the -24V closing voltage for excitation, such as Figure 4As shown, under the unloading effect of negative voltage, the current can drop to the 0A current state more quickly, shortening the closing lag process of the high-speed switching valve.

Claims

1. A high dynamic control system for solenoid valves, Features It includes a preload voltage source (1), a high voltage source (2), a regulated voltage source (3), a negative voltage source (4), a zero voltage source (5), a high-speed switching switch (6), a current detector (7), a solenoid valve (8), a pressure sensing system (9) and a controller (10); The high-speed switching switch (6) has six contact heads, wherein the first contact head (6-1), the second contact head (6-2), the third contact head (6-3), the fourth contact head (6-4) and the fifth contact head (6-5) are respectively connected to the preload voltage source (1), the high voltage source (2), the regulated voltage source (3), the negative voltage source (4) and the zero voltage source (5); the sixth contact head (6-6) is connected to the solenoid valve coil via a current detector (7); the output port of the controller (10) is connected to the high-speed switching switch (6) and can control the connection state of the sixth contact head (6-6) with the remaining contact heads; the pressure sensing system (9) is connected to each working port of the solenoid valve (8) for obtaining the pressure state of each working port of the solenoid valve; the controller (10) is connected to the pressure sensing system (9), and the controller (10) comprises a control signal generating unit.

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

3. The solenoid valve high dynamic control system according to claim 1, Features The controller (10) acquires in real time the duty cycle, frequency, rising edge time and falling edge time of the control signal generated by the control signal generating unit.

4. A solenoid valve high dynamic control method of the solenoid valve high dynamic control system as claimed in claim 1, Features The steps include: Before the rising edge of the control signal arrives, according to the duration of the preloading stage, the controller connects the sixth contact head (6-6) with the first contact head (6-1) in advance to enter the preloading stage, and after the preloading stage, the coil current is stabilized in a preloading current state that is less than the set ratio of the start-up current; When the rising edge of the control signal arrives, the controller connects the sixth contact head (6-6) with the second contact head (6-2), and the coil is stimulated by the high voltage source, and the current rises rapidly. Since the current has been stabilized in the preload current state before the rising edge of the control signal arrives, under the stimulation of the external high voltage source, the current will rise to the opening current in a short time. At this time, the solenoid valve core opens and moves, entering the opening stage, and the second contact head (6-2) and the sixth contact head (6-6) are controlled to continue to maintain connection until the solenoid valve is fully opened; Then, the controller connects the sixth contact head (6-6) to the third contact head (6-3), and the current gradually decreases and finally stabilizes at a maintaining current state that is greater than the set proportion of the closing current, so as to keep the solenoid valve in an open state; When the falling edge of the control signal arrives, the controller connects the sixth contact head (6-6) with the fourth contact head (6-4), and under the stimulation of the negative voltage source, the coil current rapidly decreases to the closing current, at which time the valve core starts to move and resets, and the negative voltage continues to stimulate until the current decreases to 0; When the current reaches 0, the controller connects the sixth contact (6-6) to the fifth contact (6-5), and the coil current continues to maintain a zero current state under the excitation of the zero voltage source until the next preloading stage arrives.

5. The high dynamic control method of the solenoid valve according to claim 4, Features The voltage value of the preload voltage source is less than the product of the solenoid valve coil resistance and the opening current, and the voltage value of the steady voltage source is greater than the product of the solenoid valve coil resistance and the closing current.

6. The high dynamic control method of a solenoid valve according to claim 4, Features The calculation process of the duration required for the preloading stage is as follows: the controller calculates the time required for the coil current to rise to the preloading current based on the current solenoid valve current, coil resistance and inductance, and based on this time, extends the set time as the duration of the preloading stage.

7. The high dynamic control method of a solenoid valve according to claim 4, Features The connection time of the second contact head (6-2) and the sixth contact head (6-6) is equal to the time required for the solenoid valve to be fully opened by being stimulated by the high voltage source in a 0 current state.

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