JPH0422083Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pneumatic device that operates with an output air pressure proportional to an input electrical signal.

[Prior Art] A conventionally known pneumatic device operated by an output pneumatic pressure proportional to an input electric signal, as shown in FIG. A nozzle flapper mechanism 5 includes a torque motor 2 driven by a signal current, a flapper 3 that swings due to the drive of the torque motor 2, and a nozzle 4 that opens opposite the flapper 3; and a feedback mechanism 7 that feeds back to the flapper 3 the position of the control valve 6 to be operated, the feedback mechanism 7
has a feedback lever 11, a shaft 12, a transmission arm 13, and a lever 14, which are rotated by a valve lever 10 that operates integrally with the control valve 6, and the lever 14 and the flapper 3 are connected to a feedback spring 15. are connected.

In the above pneumatic equipment, when a signal current is input from the controller 1 to the torque motor 2 while the nozzle flapper mechanism 5 is in an equilibrium state, a force perpendicular to each other is generated in the torque motor 2 in the directions of the current and the magnetic field. Then, the flapper 3 swings around the fulcrum 3a to open the nozzle 4, so the reduced back pressure of the nozzle is amplified by the pilot valve 8 and drives the control valve 6, which in turn drives the valve lever 10. rotates the feedback lever 11, shaft 12, and transmission arm 13 clockwise in the figure. As the transmission arm 13 rotates clockwise, the lever 14 rotates counterclockwise, and the force exerted by the feedback spring 15 on the flapper 3 and the input electric signal are transferred to the flapper 3 via the torque motor 2. When the acting forces become equal, a new equilibrium state is reached and the nozzle flapper mechanism 5 becomes stable.

However, in the above-mentioned known pneumatic equipment, the volume and weight of the electro-pneumatic converter are large because the input electrical signal is converted into pneumatic pressure by a torque motor composed of a coil, a yoke, an armature, a magnet, etc. It is difficult to make the electro-pneumatic converter small and lightweight. In addition, since materials such as permalloy with a high nickel content are usually used for the yoke and armature, the torque motor accounts for a large proportion of the product cost, making it difficult to make the electro-pneumatic converter inexpensive. be.

[Problem to be solved by the invention] The problem to be solved by the invention is to make the electro-pneumatic converter in a pneumatic device operated by an output pneumatic pressure proportional to an input electric signal smaller, lighter, and cheaper. points.

[Means for Solving the Problems] The present invention provides a pneumatic device that operates with an output pneumatic pressure proportional to an input electrical signal. The electro-pneumatic converter converts the input electrical signal and the signal pneumatic pressure into an electrical signal. A controller that compares the magnitude with a feedback electric signal fed back from a piezoelectric sensor that converts the signal into a controller and outputs a control voltage depending on the magnitude of these electric signals, a supply orifice that communicates with a pressure air source, and a a port for outputting signal air pressure; a first opening/closing valve having a piezoelectric element that opens and closes the supply orifice by being distorted by a control voltage from the controller; an exhaust orifice communicating with the outside; a port for inputting the signal air pressure; and a second opening/closing valve having a piezoelectric element that opens and closes the exhaust orifice by distorting the control voltage from the controller, thereby solving the above problem.

[Function] When the input electrical signal is input to the controller,
The controller compares the magnitude of the input electrical signal and the feedback electrical signal obtained by converting the signal air pressure from the pressure sensor, and if the input electrical signal is larger than the feedback electrical signal, the controller controls the electrical power of the first on-off valve. The signal air pressure is increased by applying a control voltage that causes the distortion element to distort the supply orifice in a direction that opens the supply orifice, and the electrostrictive element of the second on-off valve to distort the exhaust orifice in a direction that closes the exhaust orifice. As a result, when the input electric signal becomes smaller than the feedback electric signal, the controller applies a control voltage of opposite polarity to the electrostrictive elements of the first and second on-off valves, or stops applying the control voltage. release, closing the supply orifice and opening the exhaust orifice, causing the signal air pressure to drop.

Therefore, the electro-pneumatic converter outputs a signal pneumatic pressure proportional to the input electric signal, and the pneumatic operating section operates based on this signal pneumatic pressure.

In this case, when the input electrical signal is constant and the input electrical signal and the feedback electrical signal are equal, there is no air consumption in the pneumatic operating section, so it is possible to close both the supply and exhaust orifices to eliminate wasteful air consumption. can.

The electro-pneumatic converter is large in size and weight,
In addition, since a torque motor that requires expensive materials is not used, the electro-pneumatic converter can be made smaller, lighter, and less expensive.It also operates by comparing the magnitude of electrical signals, so the controller The circuit is simple.

[Embodiment] FIG. 1 shows a first embodiment of the present invention in which the pneumatic operating section is a pneumatic positioner. This pneumatic equipment is composed of an electro-pneumatic conversion section 21 and a pneumatic positioner 22.

The electro-pneumatic converter 21 includes a controller 24 to which a signal current is input, first and second on-off valves 25 and 26 using electrostrictive elements, and these on-off valves 25 and 2.
6 and the pneumatic positioner 22, and a pressure sensor 28 that converts the analog signal air pressure of the signal air pipe 27 into a feedback electric signal and feeds it back to the controller 24. compares the magnitude of the input electric signal and the feedback electric signal and applies a control voltage to the electrostrictive elements of the on-off valves 25 and 26.

The common valve body of the on-off valves 25 and 26 includes valve chambers 29a and 29b, and the valve chamber 29a has a supply orifice 30 communicating with a pressure air source and a signal air line 2.
The controller 2 has a port 31 that communicates with the controller 2.
A valve member 33 that opens and closes the supply orifice 30 is attached to the free end of the electrostrictive element 32 which is distorted by the control voltage applied from the valve member 4 . Further, the valve chamber 29b has an exhaust orifice 35 communicating with the outside and a port 36 communicating with the signal air pipe line 27,
A valve member 38 for opening and closing the exhaust orifice 35 is attached to the free end of the electrostrictive element 37, which is distorted by a control voltage applied from the controller 24.

The electrostrictive elements 32 and 37 are bimorph type, laminated type, etc. electrostrictive elements constructed by laminating plate-shaped piezoelectric ceramics that expand and contract with each other 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.

On the other hand, the pneumatic positioner 22 includes a pressure input diaphragm 41 that is displaced by the signal air pressure inputted from the signal air pipe line 27;
a nozzle flapper mechanism 44 consisting of a flapper 42 that swings according to the displacement of the flapper 42 and a nozzle 43 that opens opposite to the flapper 42; Valve stem 4 that is displaced integrally with 45
6. Valve body 48 which disconnects the communication path between pressurized air supply port P and output port A depending on the displacement of valve stem 46 and the biasing force of return spring 47, and connects output port A and diaphragm valve 49. and a feedback mechanism 51 that feeds back the drive of the diaphragm valve 49 to the pressure input diaphragm 41. The feedback mechanism 51 is rotated by a valve lever 54 that is driven integrally with the diaphragm valve 49. It has a feedback lever 55, a shaft 56, a transmission arm 57, and a lever 58, and a feedback spring 59 is provided between the lever 58 and the pressure diaphragm 41.

Next, the operation of the first embodiment will be explained.

When a signal current is input to the controller 24,
The controller 24 compares the input electrical signal with a feedback electrical signal obtained by converting the signal air pressure fed back from the pressure sensor 28, and if the feedback electrical signal is smaller than the input electrical signal, the controller 24 In the direction of opening the supply orifice 30 to the strain element 32,
Since a control voltage with a polarity that distorts the exhaust orifice 35 in the direction of closing is applied to the electrostrictive element 37, the pressure air from the pressure air source is supplied from the port 31 to the signal air pipe 27, and the signal air pressure is analogized. rise to As a result, when the feedback electrical signal becomes larger than the input electrical signal,
The controller 24 applies a control voltage of the opposite polarity to the electrostrictive elements 32 and 37 or cancels the application of the voltage to the electrostrictive elements 32 and 37 in a direction that closes the orifice 30. is returned in the direction of opening the exhaust orifice 35,
The signal air pressure decreases in an analog manner.

In this case, when the input signal is constant and the input electrical signal and the feedback electrical signal are equal, there is no air consumption in the pneumatic operating section, so both the supply and exhaust orifices can be closed to eliminate wasteful air consumption. .

Furthermore, when the controller 24 is adjusted to apply a control voltage to the electrostrictive elements 32 and 37 when the difference between the input electric signal and the feedback electric signal reaches a predetermined value, the opening and closing of the orifices 30 and 35 are controlled. Only a portion may be overlapped (meaning that the orifices are closed together) or underlap (meaning that the orifices are both open).
It can be done with or without a wrap.
This allows the controllability of the pneumatic positioner 22 to be changed.

Since the electro-pneumatic converter 21 can omit a torque motor which is large in size and weight, the electro-pneumatic converter can be made small and lightweight, and the controller 24 only compares the magnitude of the electric signals. , the circuit configuration can be made simple and inexpensive.

In the pneumatic positioner 22, when the input electric signal increases the signal air pressure in the signal air conduit 27 while the input diaphragm 41 and the nozzle flapper mechanism 44 are in equilibrium, the input diaphragm 41 moves to the left in the figure. Displaced in the direction and flattened 4
2 swings, the nozzle 43 opens, and its back pressure decreases, so the back pressure diaphragm 45 and valve stem 46, which are in communication with the pressure air source, move to the right in the figure.
Valve body 48 allows supply port P and output port A to communicate with each other.

Therefore, pressurized air is supplied through the air line 50 to the diaphragm valve 49 and the valve 4
9 is driven, and the drive of the valve 49 is fed back to the pressure input diaphragm 41 by a feedback mechanism 51. In this way, when the force exerted by the feedback spring 59 on the input pressure diaphragm 41 becomes equal to the force exerted on the input pressure diaphragm 41 by the signal air pressure, a new equilibrium state is reached, and the pressure input diaphragm 41 and the nozzle flap The mechanism 44 is stabilized.

Although not shown, the electro-pneumatic converter 21
Since it can be made small and lightweight, it can be integrated with the pneumatic positioner 22.

[Effects of the invention] The pneumatic equipment of the invention has an electro-pneumatic converter that converts an input electrical signal into a signal pneumatic pressure proportional to the input signal and outputs it, and a piezoelectric converter that converts the input electrical signal and the signal pneumatic pressure into an electrical signal. Compare the magnitude with the feedback electrical signal fed back from the sensor,
Consists of a controller that outputs a control voltage depending on the magnitude of these electrical signals, and two on-off valves that distort communication between the supply orifice and the port and the exhaust orifice and the port by distorting the control voltage from the controller. As a result, the torque motor, which is large in size and weight and requires expensive materials, can be omitted, making the electro-pneumatic converter smaller, lighter and cheaper, and the controller circuit is relatively simple. It is.

In addition, the controller in the electro-pneumatic conversion section is configured to apply a control voltage to the electrostrictive element when the difference between the input electric signal and the feedback electric signal reaches a predetermined value, and the opening and closing of the supply and exhaust orifices are lapped. The controllability of the pneumatic actuator can be changed by using a wrap or no wrap.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a conventionally known pneumatic device. 21...Electro-pneumatic conversion unit, 24...Controller,
25, 26...Opening/closing valve, 28...Piezoelectric sensor, 3
0... Supply orifice, 31, 36... Port,
32, 37...electrostrictive element, 35...exhaust orifice.

Claims (1)

[Claims for Utility Model Registration] A pneumatic device that operates with an output pneumatic pressure proportional to an input electrical signal, the pneumatic device converting an input electrical signal into a signal pneumatic pressure proportional to the input electrical signal and outputting the signal. a pneumatic converter; and a pneumatic operating part operated by a pneumatic signal from the electro-pneumatic converter; A controller that compares the magnitude with the feedback electric signal to be fed back and outputs a control voltage depending on the magnitude of these electric signals, a supply orifice that communicates with a pressure air source, and a port that outputs a signal air pressure to the pneumatic operation section. , and a first on-off valve having a piezoelectric element that opens and closes the supply orifice by distorting the control voltage from the controller; an exhaust orifice communicating with the outside; a port into which the signal air pressure is input; and control from the controller. A pneumatic device comprising: a second opening/closing valve having a piezoelectric element that opens and closes the exhaust orifice by being distorted by voltage.