CN105202252A - Drive device of pneumatic proportional valve - Google Patents

Abstract

The invention discloses a driving device for a pneumatic proportional valve, which is characterized in that the device includes a compressed air source, a solenoid valve, a controller and a cylinder; the cylinder has a piston inside, and the piston is driven up and down by the pressure difference at both ends of the piston. activities, the upper and lower ends are balanced by force, and the piston stays in place; the compressed air source provides pressure to the upper cavity and/or lower cavity of the cylinder piston through the solenoid valve; the controller provides PWM signals to control the electromagnetic Valve on and off. The invention can accurately and stably control the valve at any position of the working stroke through the on-off of the electromagnetic valve, and has good linearity; the number of components used is small and the structure is simple, and the components used are all conventional pneumatic components, so the cost is low.

Description

A driving device for pneumatic proportional valve

technical field

The invention relates to a driving device for a pneumatic proportional valve. Applicable to the field of internal combustion engines.

Background technique

In the prior art, in order to keep the proportional valve at any intermediate position, the method of controlling the input current of the spool electromagnet is often used, or the way of adjusting the intake pressure through the solenoid valve group is realized.

For example: CN201310010367.7 Pneumatic proportional pressure valve, a pneumatic proportional pressure valve, including an upper casing and a lower casing, the inner hole of the upper casing is provided with a main valve core, and the right end of the main valve core is connected to the left end of the upper valve core; The right end of the upper spool is connected to the proportional electromagnet; the left end of the main spool is fixed with a valve port assembly, and the valve port assembly of the main spool is connected to the main spool spring seat through the main spool return spring, and the main spool spring seat is used through the hole. The circlip is fixedly connected to the upper shell; the lower shell is provided with a cup, and an air pressure control chamber is formed between the right side of the cup and the left side of the upper shell; a working hole is opened on the lower shell on the left side of the cup , exhaust hole and overflow hole; the overflow hole is connected with the exhaust hole and the working hole respectively; the working hole is directly connected with the load, the exhaust hole is directly connected to the atmosphere, and the overflow valve assembly is arranged in the overflow hole. The spool of the pneumatic proportional pressure valve is driven by an electromagnet, and the proportional electromagnet receives the input current signal from the controller and converts it into an output force; when the input current increases, the output force of the proportional electromagnet increases to overcome the return spring of the main spool With the spring force of the upper spool return spring, the main spool and the upper spool move to the left together, making the valve port open; when the input current decreases, the output force of the proportional solenoid decreases, and the upper spool is reset by the upper spool The spring pushes to move to the right first, separates from the main valve core, and discharges the gas in the control chamber into the atmosphere through the small cavity of the upper casing, and due to the decrease of the force, the valve opening of the main valve core becomes smaller, The throttling effect is strengthened, so that the pressure in the control chamber drops, and the pressure on the left side of the cup remains at the pressure value before the current decreases, so that there is a pressure difference on both sides, pushing the cup to the right, and the cup no longer seals the air hole; The one-way action of the bowl, in the process of moving to the right, the lip is always in a state of tension under the pressure of the left side, isolating the control chamber and the working hole, and because the cup moves to the right, the exhaust hole and the working hole are connected , the gas in the load is quickly discharged to the atmosphere; when the gas pressure in the load hole drops to a certain value, the left and right sides of the cup, that is, the gas pressure of the load and the working chamber, re-balance, and the cup returns to the initial position, and the exhaust hole and the working hole It is no longer connected, and the gas is no longer expelled. The solution is that the compressed air is connected to a cavity through a proportional solenoid valve. The proportional solenoid valve can linearly control the pressure of the cavity. When the pressure of the cavity is greater than the pressure of the load end, the compressed air in the cavity will enter the load end. , so that the pressure at the load end rises until the pressure between the two is balanced. When the pressure of the cavity is lower than the load end, the air at the load end will be discharged into the atmosphere, thereby reducing the pressure at the load end until the pressure between the two is balanced. The pressure at the load end is indirectly controlled, the response is relatively slow, and the structure of the pneumatic proportional valve is complex, difficult to process, and expensive.

Another example: CN201110205797.5 A pneumatic proportional adjustment device based on electromagnetic valve array, which includes a main valve body, an upper end cover, a lower end cover, an inlet electromagnetic valve array and an air outlet electromagnetic valve array. Air cavity, intake air path and exhaust air path, pressure sensor and circuit board are installed on the top of the main valve body, and the upper end cover is installed on the top of the main valve body to accommodate the pressure sensor and circuit board; the bottom of the main valve body is installed with the lower end cover; the left and right sides of the main valve body are respectively equipped with an air intake solenoid valve array and an air outlet electromagnetic valve array; the front side of the main valve body is provided with a first interface and a second interface respectively connected with the air intake air circuit and the air cavity. The intake solenoid valve array includes solenoid valves of at least two diameters, and each solenoid valve is connected to two air ports opened on the left side of the main valve body, one of which is connected to the air cavity, and the other is connected to the intake air path. The exhaust solenoid valve array includes solenoid valves of at least two diameters, and each solenoid valve is connected to two air ports opened on the right side of the main valve body, one of which is connected to the air cavity, and the other is connected to the exhaust port. The gas path is connected. This scheme realizes the pressure adjustment of the pressure chamber through the combination of the number of solenoid valves opened by the intake solenoid valve group and the exhaust solenoid valve group. As the number of valves opened by the valve group increases, the air pressure decreases. This method requires the use of many solenoid valves with complex structures, and the linearity of air pressure control is poor.

Contents of the invention

The object of the present invention is to provide a driving device and a driving method for a pneumatic proportional valve with simple structure, good linearity and fast response speed in view of the above defects in the prior art.

In order to achieve the above object, the present invention adopts the following technical solutions:

A driving device for a pneumatic proportional valve, characterized in that the device includes a compressed air source, a solenoid valve, a controller and a cylinder; the cylinder has a piston inside, and the piston is driven to move up and down by the pressure difference between the two ends of the piston. The force on the end is balanced, and the piston stays in position; the compressed air source provides pressure to the upper cavity and/or lower cavity of the cylinder piston through the switching of the solenoid valve; the controller provides a PWM signal to control the switching of the solenoid valve.

One method: a compression spring is arranged under the piston to provide an upward force to the piston; the solenoid valve is a two-position three-way solenoid valve, which has two working states of I and II, and the state is controlled by the PWM signal of the controller. Switching; in working state Ⅰ, the compressed air provided by the compressed air source enters the upper cavity of the cylinder piston after passing through the solenoid valve, and drives the piston to overcome the elastic force of the compression spring to go down; in the working state Ⅱ, the compressed air in the upper cavity of the cylinder piston passes through the electromagnetic valve. After the valve enters the cavity at the lower end of the piston of the cylinder and is discharged into the atmosphere, the elastic force of the compression spring drives the piston upward.

Preferably: the compressed air of the compressed air source enters the upper cavity of the cylinder piston through the one-way valve and then through the solenoid valve; the compressed air in the upper cavity of the cylinder piston is divided into two parts through the solenoid valve and then through the one-way valve. One way goes through the throttle valve and then enters the lower end cavity of the cylinder piston, and the other way goes through the one-way valve and then discharges into the atmosphere.

Another form: the solenoid valve is a two-position five-way solenoid valve, which has two working states of I and II, and is switched under the control of the PWM signal of the controller; in working state I, the compressed air provided by the compressed air source is passed through The solenoid valve enters the upper cavity of the cylinder piston, and the air in the lower cavity of the cylinder piston is discharged into the atmosphere after passing through the solenoid valve. After the valve, it enters the lower end cavity of the cylinder piston, and the air in the upper end cavity of the cylinder piston is discharged into the atmosphere after passing through the solenoid valve, and the pressure difference at both ends of the piston drives the piston upward.

Preferably: the compressed air provided by the compressed air source passes through the one-way valve and then enters the upper cavity or the lower cavity of the cylinder piston through the solenoid valve; the compressed air in the upper cavity and the lower cavity of the cylinder piston passes through the solenoid valve Then it is discharged into the atmosphere after the one-way valve and the throttle valve.

The duty cycle value of the PWM signal of the above-mentioned controller is controlled by a method of PID regulation.

An induction body is fixed on the piston of the cylinder, and a position sensor is fixed on the casing of the cylinder, and the position sensor outputs a corresponding signal to the controller according to the position of the induction body, and the controller formulates according to the obtained position signal and the target position signal. A control strategy controls the solenoid valve.

The positive effects of the present invention are: through the on-off of the electromagnetic valve, the valve can be accurately and stably controlled at any position of the working stroke, and the linearity is good; the number of components used is small and the structure is simple, and the components used are all conventional pneumatic components, reducing the cost. Low.

Description of drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

Fig. 2 is a schematic diagram of working state I of the structure in Fig. 1 .

Fig. 3 is a schematic diagram of working state II of the structure in Fig. 1 .

Fig. 4 is a schematic structural diagram of another embodiment of the present invention.

Fig. 5 is a schematic diagram of working state I of the structure in Fig. 4 .

FIG. 6 is a schematic diagram of working state II of the structure in FIG. 4 .

Detailed ways

Example 1:

As shown in Figure 1-3, the solenoid valve 13 has two working states of I and II, and three channels of P, A, and T, wherein channel A is connected to channel 17, channel P is connected to one-way valve 15, and channel T is connected with check valve 2, check valve 15 is downstream of compressed air source 1, check valve 2 is downstream of channel T, check valve 14 is downstream of check valve 2, throttle valve 3 is downstream of check valve 2 To the upstream of the valve 14, the electromagnetic valve 13 can be a double-coil type or a single-coil type. Each coil of the double-coil type controls a working state. If a double-coil type is used, the two coils are controlled by complementary signals. The control signal directly controls one of the coils, and controls the other coil after reverse processing. The single-coil coil only controls from one state to another state when it is energized, and when it returns to the original state, the coil is de-energized through the spring. If you use a single coil The control signal directly controls the coil. The cylinder 19 is a single-acting cylinder, the downward movement of the piston 20 is driven by the active force of the air pressure, and the upward movement is driven by the spring force. An induction body 29 is fixed on the piston 20 of the cylinder 19, and a position sensor 30 is fixed on the casing of the cylinder 19, and the position sensor 30 can output a corresponding signal to the controller 4 according to the position of the induction body 29, and the controller 4. Formulate a control strategy to control the solenoid valve 13 according to the obtained position signal and the target position signal, so that the piston 9 moves to the target position quickly and accurately and stabilizes at the target position. The spring 23 not only has the function of driving, but also has the function of returning to the zero position of the valve when the system stops working.

2 and 3 are schematic diagrams of two working states of the solenoid valve 13 . As shown in Figure 2, when the solenoid valve 13 is working in working state I, the one-way valve 15 is opened, the channel P communicates with the channel A, and the air enters through the one-way valve 15, the channel P, the channel A, and the channel 17. In the cavity 18; the air pressure in the cavity 18 causes the piston 20 to move downward against the spring force of the spring 23, and the air in the cavity 21 will generate a certain air pressure under the action of the piston 20, and the check valve 14 will move downward under the action of the air pressure. Open, the air in the cavity 21 is discharged into the atmosphere through the throttle valve 3 and the one-way valve 14 . As shown in Figure 3, when the solenoid valve 13 is working in the working state II, the passage T communicates with the passage A, the piston 20 moves upward under the action of the spring force of the spring 23, a negative pressure is formed in the cavity 21, and at the same time the cavity The air pressure in 18 makes check valve 2 open, and a part of air in cavity 18 enters in cavity 21 through channel 17, channel A, channel T, check valve 2, throttle valve 3, channel 24; At the time of I, the cavity 18 is filled with high-pressure air. After switching to the working state II, the air in the cavity 18 will enter the pipeline at the positive end of the one-way valve 14, so that the air pressure at the positive end is higher than that at the negative end, and the one-way valve 14 will open. , a part of the air in the cavity 18 will be discharged into the atmosphere through the channel 17, the channel A, the channel T, the check valve 2, and the check valve 14.

The solenoid valve 13 is controlled by the PWM signal to quickly switch between the I and II states, and the cycle value of the switch is the same as that required for the opening of the one-way valve 2, the one-way valve 14, and the one-way valve 15 when the air flows forwardly. Timings are matched to achieve the following effects:

When the solenoid valve 13 is switched from the working state II to the working state I, the channel T is closed, there is no positive pressure difference across the check valve 2, the check valve 2 is closed, and the check valve 15 is opened by the positive pressure difference , but it takes a while to open, and even if the one-way valve 15 is opened and a small amount of compressed air enters the cavity 18, the air in the cavity 21 will hinder the downward movement of the piston 20 when the one-way valve 14 is not opened. , although the one-way valve 14 has a tendency to open due to the positive pressure difference at this time, it takes a certain amount of time to open, and the solenoid valve 13 switches from working state I to Working state II; when the solenoid valve 13 is switched from working state I to working state II, the channel P is closed, and there is no positive pressure difference between the two ends of the check valves 15 and 14, they will be closed, and the check valve 2 is positively The differential pressure has a tendency to open, but it takes a period of time to open, and the solenoid valve 13 is switched from working state II to working state I before the check valve 2 is opened or opened soon.

The above control method can make the air entering and exiting the cavity 18 seldom and the air entering and exiting alternately, the intake air volume is equal to the air output volume, the pressure of the cavity 18 remains stable, and the piston 20 is stable at a fixed position. By adjusting the duty cycle of the PWM signal, the air pressure of the cavity 18 can be adjusted between the atmospheric pressure and the air pressure of the compressed air source 1, so that the position of the piston 20 can be adjusted at any target position within the working stroke.

The function of the throttle valve 3 is to make the moving speed of the piston 20 meet the requirement, and at the same time, a PWM signal with a larger period can be used to control the solenoid valve 13 to improve its reliability. Cancellation of the one-way valve 15 compressed air source 1 directly communicates with the channel P, or cancels the throttle valve 3, and the negative end of the one-way valve 2 and the positive end of the one-way valve 14 are directly communicated with the channel 24, all of which belong to this preferred solution.

Example 2:

Figure 4 shows a schematic diagram of the principle of the invention. Solenoid valve 13 is a two-position five-way solenoid valve with two working states of I and II and five channels of P, A, B, R, and S, of which channel A is connected to channel 6, channel B is connected to channel 12, and channel P It is connected with check valve 15, channel R is connected with check valve 2, channel S is connected with check valve 14, check valve 15 is downstream of compressed air source 1, check valve 2 is downstream of channel R, and check valve 14 is in Downstream of the channel S, the throttle valve 3 is downstream of the one-way valves 2 and 14. The solenoid valve 13 can be a double-coil type or a single-coil type. Each coil of the double-coil type controls a working state. In the coil type, the two coils are controlled by complementary signals. The control signal directly controls one of the coils, and controls the other coil after reverse processing. The single-coil type coil only controls from one state to another state, and returns to the original state. Then the coil power-off is realized by the spring, and if a single-coil type is used, the control signal directly controls the coil. The cylinder 7 is a double-acting cylinder, and the upward and downward movements of the piston 9 are all driven by air pressure. An induction body 29 is fixed on the piston 9 of the cylinder 7, and a position sensor 30 is fixed on the casing of the cylinder 7, and the position sensor 30 can output corresponding signals to the controller 4 according to the position of the induction body 29, and the controller 4. Formulate a control strategy to control the solenoid valve 13 according to the obtained position signal and the target position signal, so that the piston 9 moves to the target position quickly and accurately and stabilizes at the target position. The spring force of spring 31 is very little, only realizes the return effect of valve when the system stops working, and does not play the effect of driving valve, if valve itself has return device spring 31 can cancel.

Figures 5 and 6 are schematic diagrams of two working states of the solenoid valve 13. When the solenoid valve 13 is working in working state II, the check valve 15 is opened, the channel P communicates with the channel B, and the compressed air passes through the one-way valve. The directional valve 15, channel P, channel B, and channel 12 enter the cavity 10; the channel R communicates with the channel A, and the one-way valve 2 is opened under the air pressure in the cavity 8, and the air in the cavity 8 passes through the channel 6. Channel A, channel R, check valve 2, and throttle valve 3 are discharged into the atmosphere, and piston 9 moves upward. When the solenoid valve 13 is working in the working state I, the one-way valve 15 is opened, the channel P communicates with the channel A, and the compressed air enters the cavity 8 through the one-way valve 15, the channel P, the channel A, and the channel 6; Channel S communicates with channel B, the one-way valve 14 is opened under the action of air pressure in the cavity 10, and the air in the cavity 10 passes through the channel 12, channel B, channel S, one-way valve 14, throttle valve 3 rows Into the atmosphere, the piston 9 descends.

When the distance between the position of the piston 9 and the target position is greater than the first threshold, the solenoid valve 13 is controlled by a switch signal, so that the solenoid valve 13 works in working state I or working state II, and the piston 9 moves quickly to the target position . When the distance between the position of the piston 9 and the target position is less than the first threshold value and greater than the second threshold value, the solenoid valve 13 is controlled by a PWM signal whose period is the first period value, so that the solenoid valve 13 is in working state I and Switching between working states II, the switching cycle is equal to the first cycle value, the duty cycle is equal to the duty cycle of the PWM signal, the duty cycle of the PWM signal is controlled by PID adjustment, and the piston 9 moves toward the target at a faster speed. The position moves without over-adjusting. When the distance between the position of the piston 9 and the target position is less than the second threshold value, the solenoid valve 13 is controlled by a PWM signal whose period is the second period value, so that the solenoid valve 13 is between working state I and working state II Switching, the switching period is equal to the second period value, the duty ratio is equal to the duty ratio of the PWM signal, the duty ratio of the PWM signal is controlled by PID adjustment, the second period value and the air flow through the Check valve 2, check valve 14, and check valve 15 match the time required for their opening to achieve the following effects:

When the electromagnetic valve 13 is switched from the working state I to the working state II, there is no positive pressure difference between the two ends of the one-way valve 14, the one-way valve 14 will be closed, and the positive end of the one-way valve 2 communicates with the cavity 8. It will be opened under the action of pressure difference, but it will take a while to open, and the solenoid valve 13 will switch from the working state II to the working state I before the check valve 2 is opened or soon after it is opened, so only a little air is discharged from the cavity 8, The situation is the same when the solenoid valve 13 switches from the working state II to the working state I, only a little air is discharged from the cavity 10, the pressure difference between the cavity 8 and the cavity 10 remains stable, and the piston 9 is stable at the target position .

The function of the throttle valve 3 is to make the moving speed of the piston 9 meet the requirement, and at the same time, a PWM signal with a larger period can be used to control the solenoid valve 13 to improve its reliability. Cancel the one-way valve 15, the compressed air source 1 directly communicates with the channel P, or cancel the throttle valve 3, and the negative ends of the one-way valves 2 and 14 directly connect to the atmosphere, which all belong to this preferred solution.

Claims (7)

1. A drive device for a pneumatic proportional valve, characterized in that: the device comprises a compressed air source, a solenoid valve, a controller and a cylinder; a piston is arranged in the cylinder, and the piston is driven to move up and down by the pressure difference at both ends of the piston, The force on the upper and lower ends is balanced, and the piston stays in position; the compressed air source provides pressure to the upper cavity and/or lower cavity of the cylinder piston through the solenoid valve; the controller provides a PWM signal to control the solenoid valve. broken. 2. The driving device of the pneumatic proportional valve according to claim 1, characterized in that: a compression spring is provided under the piston to provide upward force to the piston; the solenoid valve is a two-position three-way solenoid valve with I Two working states, Ⅱ and Ⅱ, are switched under the control of the PWM signal of the controller; in working state Ⅰ, the compressed air provided by the compressed air source enters the upper cavity of the piston of the cylinder after passing through the solenoid valve, and the piston is driven to overcome the elastic force of the compression spring to move downward; In working state II, the compressed air in the upper cavity of the cylinder piston enters the lower cavity of the cylinder piston through the solenoid valve and is discharged into the atmosphere, and the elastic force of the compression spring drives the piston upward. 3. The driving device of the pneumatic proportional valve according to claim 2, characterized in that: the compressed air from the compressed air source enters the upper cavity of the cylinder piston through the one-way valve and then through the solenoid valve; The compressed air in the upper cavity is divided into two paths through the solenoid valve and then through the one-way valve. One path enters the lower cavity of the cylinder piston after passing through the throttle valve, and the other path is discharged into the atmosphere after passing through the one-way valve. 4. The driving device of the pneumatic proportional valve according to claim 1, characterized in that: the solenoid valve is a two-position five-way solenoid valve, which has two working states of I and II, and the state is controlled by the PWM signal of the controller. Switching; in working state I, the compressed air provided by the compressed air source enters the upper cavity of the cylinder piston after passing through the solenoid valve, and the air in the lower cavity of the cylinder piston is discharged into the atmosphere after passing through the solenoid valve, and the pressure difference at both ends of the piston drives the piston down ; In working state II, the compressed air provided by the compressed air source enters the lower cavity of the cylinder piston through the solenoid valve, and the air in the upper cavity of the cylinder piston passes through the solenoid valve and is discharged into the atmosphere, and the pressure difference at both ends of the piston drives the piston upward. 5. The driving device of the pneumatic proportional valve according to claim 4, characterized in that: the compressed air provided by the compressed air source enters the upper or lower cavity of the cylinder piston through the one-way valve and then through the solenoid valve; The compressed air in the upper cavity and the lower cavity of the piston of the cylinder is discharged into the atmosphere through the electromagnetic valve, the one-way valve and the throttle valve. 6. The driving device of a pneumatic proportional valve according to any one of claims 1-5, characterized in that: the duty cycle value of the PWM signal of the controller is controlled by a PID adjustment method. 7. The driving device of a pneumatic proportional valve according to any one of claims 1-5, characterized in that: an induction body is fixed on the piston of the cylinder, a position sensor is fixed on the shell of the cylinder, and the position The sensor outputs a corresponding signal to the controller according to the position of the induction body, and the controller formulates a control strategy to control the solenoid valve according to the obtained position signal and target position signal.