JPH0432243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to pneumatic equipment that operates with an output pneumatic pressure proportional to an input electrical signal.

[Prior Art] The inventors of the present invention have provided an electro-pneumatic conversion section that converts an input electrical signal into pneumatic pressure proportional to the electrical signal and outputs it, and a pneumatic operation section that operates based on the signal pneumatic pressure. A pneumatic device using a directional switching valve having an electrostrictive element in the electro-pneumatic conversion part was proposed in 1983.
Proposed by No. 112939 and others.

As shown in FIG. 7, for example, the pneumatic equipment includes an electro-pneumatic conversion section 1 and a pneumatic positioner 2, which is an example of a pneumatic operation section.

The electro-pneumatic converter 1 includes a controller 4 into which a signal current is input, a directional switching valve 5 using an electrostrictive element, and a signal air pipe line that transmits the signal air pressure output from the directional switching valve 5 to a pneumatic positioner. 6, and a pressure sensor 7 that converts the signal air pressure of the signal air pipe line 6 into a feedback electric signal and feeds it back to the controller 4, and the controller 4 compares the magnitude of the input electric signal and the feedback electric signal. Then, a control voltage is applied to the electrostrictive element 13 of the directional switching valve 5.

The valve body 9 of the directional valve 5 has a supply orifice 10 communicating with a source of pressurized air, an exhaust orifice 11 communicating with the outside, and an output port 12 communicating with the air line 6, and receives a control voltage applied from the controller 4. Valve members 14, 14 for opening and closing the orifices 10, 11 are attached to the free end of the electrostrictive element 13, which is distorted by the movement. The electrostrictive element 13 is a bimorph type electrostrictive element made by laminating plate-shaped piezoelectric ceramics on both sides of electrodes that expand and contract depending on the polarity of applied voltage. When a voltage of opposite polarity is applied or the application of the voltage is removed, it is distorted in the opposite direction or returns to its original state.

The pneumatic positioner 2 includes a pressure diaphragm 17 that is displaced by a signal air pressure input from a signal air pipe 6, a flapper 18 that swings due to the displacement of the diaphragm 17, and an opening facing the flapper 18. a nozzle flapper mechanism 20 consisting of a nozzle 19, a back pressure diaphragm 21 that is displaced as the back pressure of the nozzle 19 rises and falls, a valve stem 22 that is displaced integrally with the back pressure diaphragm 21, and the valve stem 2.
2 and the magnitude of the biasing force of the return spring 23, the valve body 24 disconnects the communication path between the pressurized air supply port P and the output port A, and the air pipe line connects the output port A and the diaphragm valve 25. 26, and a feedback mechanism 27 that feeds back the drive of the diaphragm valve 25 to the pressure input diaphragm 17. Clever 31, shaft 32, transmission arm 33 and lever 3
4, and a feedback spring 35 is provided between the lever 34 and the pressure diaphragm 17. Reference numeral 37 in FIG. 7 is a throttle provided in the signal air conduit 6, which eliminates pressure fluctuations (pulsations) caused by the operation of the directional valve 5 and makes the signal air pressure analogous.

In the pneumatic equipment, when a signal current is input to the controller 4, the controller 4 compares the input electric signal with a feedback electric signal obtained by converting the signal air pressure fed back from the pressure sensor 7, and converts the input electric signal into a feedback electric signal. is smaller than the input electrical signal, controller 4
However, since a control voltage with a polarity that distorts the electrostrictive element 13 in the direction of opening the supply orifice 10 and closing the exhaust orifice 11 is applied, the pressurized air from the pressurized air source passes through the output port 12 to the signal air pipe. When the signal air pressure is supplied to the electrostrictive element 1 and increases, thereby causing the feedback electrical signal to become larger than the input electrical signal, the controller 4 causes the electrostrictive element 1 to
3, or by canceling the application of the voltage, the electrostrictive element 13 is returned to the direction in which the supply orifice 10 is closed and the exhaust orifice 11 is opened. As long as the signal air pressure in the line 6 decreases and the feedback electric signal becomes smaller than the input electric signal, and the electric signal is input to the controller 4, the directional control valve 5 repeats the above-described operation.

In this case, by performing the opening/closing operation frequently, an analog signal air pressure proportional to the input electrical signal is output from the output port 12.

The pneumatic positioner 2 receives a signal from the air conduit 6 by an input electrical signal when the pressure diaphragm 17 and the nozzle flapper mechanism 20 are in equilibrium.
When the signal air pressure increases, the pressure diaphragm 1
7 is displaced to the left in the figure, the flapper 18 swings, the nozzle 19 opens, and its back pressure decreases, so that the back pressure diaphragm 21 and valve stem 22 communicating with the pressure air source are Move to the right, valve body 2
4 connects the supply port P and the output port A.

Therefore, pressurized air is supplied to the diaphragm valve 25 through the air line 26 and the valve 2
5 is driven, and the drive of the valve 25 is fed back to the pressure input diaphragm 17 by a feedback mechanism 27. In this way, when the force exerted by the feedback spring 35 on the input pressure diaphragm 17 becomes equal to the force exerted on the input pressure diaphragm 17 by the signal air pressure, a new equilibrium state is reached and the pressure input diaphragm 17 and the nozzle flap The mechanism 20 is stabilized.

In the pneumatic equipment proposed above, if no throttle is installed in the signal air conduit 6, some pulsation remains in the signal air pressure when the input electric signal is applied stepwise (see FIG. 8). Although the magnitude of this pulsation can be made very small by designing each constant to an optimal value, it is technically difficult to completely eliminate it. However, when this pneumatic equipment is used in a signal system or the like, it is necessary to completely eliminate pulsation.

In this case, by installing a throttle 37 in the signal air pipe line 6, the pulsation of the signal air pressure can be completely eliminated, but the throttle increases the time _t1 for the signal air pressure to reach a predetermined pressure ( (see FIG. 9), in other words, a new problem arises in that the responsiveness of the pneumatic equipment decreases.

[Problems to be Solved by the Invention] The present invention provides electro-pneumatic conversion by providing a second directional valve that communicates the output port of the first directional valve with the pneumatic operating section directly or through a restriction. The problem to be solved is to improve the responsiveness of the air pressure while eliminating the pulsations in the air pressure output from the air pressure section.

[Means for Solving the Problems] The present invention provides an electro-pneumatic conversion section that converts an input electrical signal into pneumatic pressure proportional to the input electrical signal and outputs it;
In this pneumatic device comprising a pneumatic operating section operated by air pressure, the electro-pneumatic conversion section includes a supply orifice communicating with a pressure air source, an exhaust orifice communicating with the outside, an output port communicating with the pneumatic operating section, and a first directional control valve having an electrostrictive element that distorts the input electric signal in response to the input electric signal and switches the output port to communicate with one of the two orifices; The above problem is solved by including a second directional control valve that switches the output port that communicates directly with the pneumatic operating section to a position where it communicates through a throttle.

[Function] When an input electric signal is input, the supply orifice is opened and the exhaust orifice is closed by the electrostrictive element which distorts in response to the input electric signal. Pneumatic pressure is output, and the pneumatic operating section is operated by this pneumatic pressure.

Initially, the air pressure is directly communicated with the pneumatic operating section, so the air pressure of the pneumatic operating section quickly increases. After a predetermined period of time has elapsed, the second directional control valve is switched to a position where it communicates with the pneumatic operating section via the throttle, so that the pulsation of air pressure can be eliminated by the throttle. Furthermore, since the time required for the air pressure to reach a predetermined pressure is shortened, the responsiveness of the device can be improved.

[Embodiment] FIG. 1 shows a first embodiment of the present invention, and this embodiment includes a first directional control valve 4 having an electrostrictive element 13.
A second directional switching valve 42 in place of the throttle 37 is provided in the signal air conduit 6 that communicates the output port 12 of the pneumatic positioner 2 with the pneumatic positioner 2 . Since the other configuration of the first embodiment is the same as the previously proposed pneumatic equipment shown in FIG. 7, the same reference numerals are given in the figure and detailed explanation will be omitted.

The second directional control valve 42 is connected to the output port 12.
an inlet port 43 communicating directly with the signal air line 6 , a first outlet port 44 communicating directly with the signal air line 6 , and a second outlet port 45 , the second outlet port 45 communicating directly with the signal air line 6 through a restriction 46 . The solenoid 42a of the switching valve 42 is electrically connected to the controller 4 via a delay circuit 47.

In the delay circuit 47, the signal air pressure that increases due to the application of voltage to the electrostrictive element 13 is approximately 50% of the output pressure.
-97%, preferably 90-95%, the solenoid 42a is energized. When the solenoid 42a is energized, the inlet port 43 communicating with the first outlet port 44 is connected to the second outlet port. 45
The signal air pressure is transmitted to the pneumatic operating section 2 via the throttle 46.

Therefore, before the delay time elapses, the responsiveness of the device can be improved by directly transmitting the signal air pressure to the pneumatic operating unit 2 and shortening the time _t2 for the signal air pressure to reach a predetermined pressure. After the delay time has elapsed, the pulsation of the signal air pressure can be completely eliminated by transmitting the signal air pressure to the air pressure operating section via the throttle 46 (see FIG. 2).

When the input electric signal is released, the second directional switching valve 42 returns to the position where the inlet port 43 and the first outlet port 44 communicate with each other by the biasing force of the return spring.

The other operations of the first embodiment are the same as those of the pneumatic equipment shown in FIG. 7, so a detailed explanation will be omitted.

FIG. 3 shows how the second directional control valve 50 is operated at the inlet port 51 by de-energizing and energizing the solenoid 50a.
A modified example is shown in which a two-port valve is used to cut off communication between the valve and the outlet port 52, and the signal air line 6 is provided with a throttle 54 in a bypass 53 connected in parallel with the second directional control valve 50.

When the solenoid 50a is de-energized, the directional control valve is connected to the output port 1 of the first directional control valve 41.
2 communicates with the signal air line 6 by a directional valve 50 and a bypass 54, and by a bypass 53 with a throttle 54 when the solenoid 50a is energized.

FIG. 4 shows another modified example in which the second directional control valve 60 has an inlet orifice 61, an outlet port 62, and an electrostrictive element 63 that opens and closes the inlet orifice 61 by applying and removing voltage. , the signal air line 6 is provided with a restriction 65 in a bypass 64 connected in parallel with the second directional valve 60 .

In the directional switching valve, when no control voltage is applied to the electrostrictive element 63, the inlet orifice 61 and the output port 62 communicate with each other, and when the control voltage is applied via the delay circuit 47, the electrostrictive element 63 is distorted. to close the inlet orifice 61.

FIG. 5 shows a second embodiment of the present invention in which the pneumatic operation section is a control valve 70 having a feedback mechanism to an electropneumatic conversion section 69, and the controller 4 and the first directional control valve 4 in the second embodiment
Since the first and second directional switching valves 42 have the same configuration as in the first embodiment, they are designated by the same reference numerals in the drawings, and detailed description thereof will be omitted. Note that the second directional switching valve may be the directional switching valves 50 and 60 shown in FIGS. 3 and 4.

The feedback 71 in the control valve 70 is operated by a feedback lever 73, a support shaft 74, a feedback cam 75, and a press of the feedback cam 75, which are rotated by a valve lever 72 that is driven integrally with the control valve 70. A cantilever 76 that twists and flexes, a displacement sensor 77 that is attached to the cantilever 76 and converts the displacement of the cantilever 76 into an electric signal proportional to it and outputs it, and a feedback electric signal output from the displacement sensor 77 is fed back to the controller 4. A feedback circuit 78 is provided, and the feedback cam 75 has a cam surface whose distance from the support shaft increases as it rotates clockwise in the figure.

Therefore, when the control valve 70 is driven by the output air pressure from the first directional control valve 4 due to the application of a control voltage to the electrostrictive element 13, the valve lever 72 moves downward as shown in the figure, and the feedback is controlled. The lever 73, the support shaft 74, and the feedback cam 75 are rotated clockwise in the figure, and the roll 79 at the tip of the cantilever is pressed by the cam 75, displacing the cantilever 76.
The upper displacement sensor 77 converts this displacement into a proportional feedback electrical signal and feeds it back to the controller 4.

Second directional control valve 42 in the second embodiment
Or, since the actions of 50 and 60 are as described above, detailed explanation will be omitted.

FIG. 6 shows a modification in which the first directional control valve 80 is made up of two on-off valves 81 and 82 using electrostrictive elements, and the common valve body in this directional control valve 80 is valve chambers 83a and 83b. The valve chamber 83a has a supply orifice 10 that communicates with a source of pressurized air and a port 84 that communicates with an air line 88.The free end of an electrostrictive element 85 that is distorted by a control voltage applied from the controller 4 , a valve member 14 for opening and closing the supply orifice 10 is attached. On the other hand, the valve chamber 83b has an exhaust orifice 11 communicating with the outside.
A valve member 14 for opening and closing the exhaust orifice 11 is attached to the free end of an electrostrictive element 87 that is distorted by a control voltage applied from the controller 4. These electrostrictive elements 85 and 87 are similar to the electrostrictive element 1.
It has the same configuration as 3.

Although not shown, the air pipe line 88 is provided with the above-mentioned second directional control valve 42 or 50, 60.

The directional switching valve 80 is configured such that when the feedback electric signal is smaller than the input electric signal, the controller 4 opens the supply orifice 10 to the electrostrictive element 85 and closes the exhaust orifice 11 to the electrostrictive element 87. Since a control voltage of a polarity that causes distortion is applied respectively, pressurized air from the pressurized air source is supplied from the port 84 to the air line 88, and the air pressure is increased in an analog manner. As a result, when the feedback electric signal becomes larger than the input electric signal, the controller 4 causes the electrostrictive element 85,
87, or by canceling the application of the voltage, the electrostrictive element 85 is supplied with the electrostrictive element 85 in the direction of closing the orifice 10.
7 is returned in the direction of opening the exhaust orifice 11, the air pressure decreases in an analog manner.

In this case, when the input electrical signal is constant and the input electrical signal and the feedback electrical signal are equal,
Since there is no air consumption in the pneumatic working part, it can be closed together with the supply and exhaust orifices to eliminate wasteful air consumption.

Although not shown, the first directional valves 41, 80 and the second directional valves 42, 50, 6
By making 0 integral, it can be made compact. Further, the pneumatic operating section can also be configured in other ways, such as a booster relay.

[Effects of the Invention] The pneumatic equipment of the present invention is provided with a second directional switching valve that switches the output port of the first directional switching valve between a position in which it communicates directly with the pneumatic operating section and a position in which it communicates through a throttle. At the same time, the directional control valve is directly communicated with the pneumatic operating section, and after a predetermined period of time has elapsed, communication is made via the throttle by an input electrical signal, thereby eliminating pulsation of the signal pneumatic pressure from the electro-pneumatic converting section. Although it is possible to do this, it is possible to improve the responsiveness of the device.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of the first embodiment of the present invention, FIG. 2 is an example of waveforms of the input electrical signal and output air pressure, and FIGS. 3 and 4 are modifications of the second directional control valve. FIG. 5 is a schematic diagram of the second embodiment of the present invention, FIG. 6 is a schematic diagram of a modification of the first directional valve, and FIG. 7 is a schematic diagram of the previously proposed pneumatic equipment. The configuration diagram, FIG. 8, and FIG. 9 are examples of the waveforms of the input electrification signal and the signal air pressure when there is no throttle and when the throttle is provided. 1, 69... Electro-pneumatic conversion unit, 2... Pneumatic positioner, 10... Supply orifice, 11... Exhaust orifice, 12... Output port, 13, 63, 8
5, 87... Electrostrictive element, 41, 80... First directional switching valve, 42, 50, 60... Second directional switching valve, 46, 54, 65... Throttle, 70... Control valve.

Claims (1)

[Scope of Claims] 1. A pneumatic device comprising an electro-pneumatic conversion section that converts an input electrical signal into pneumatic pressure proportional to the input electrical signal and outputs the pneumatic pressure, and a pneumatic operation section that operates based on this air pressure, A converting section includes a supply orifice communicating with a source of pressurized air, an exhaust orifice communicating with the outside, an output port communicating with the pneumatic operating section, and a converter correspondingly distorting the input electrical signal and connecting the output port to one of the two orifices. a first directional control valve having an electrostrictive element that is switched to one side for communication; and after a predetermined time elapses, the input electric signal causes
A pneumatic device comprising: a second directional control valve that switches the output port that directly communicates with the pneumatic operating section to a position where it communicates through a throttle.