JPH0448325Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an electro-pneumatic converter that controls air output in response to input current.

More specifically, the present invention relates to an electropneumatic converter that improves the stability of a control loop.

(Prior Art) FIG. 3 is a diagram illustrating the configuration of a conventional example that has been commonly used.

In the figure, 1 is a torque motor that drives a movable piece 11 in response to an input current Iin. A nozzle 2 is provided opposite one end of the movable piece 11 and constitutes a nozzle flapper mechanism. 3 has a diaphragm 30, an exhaust valve 31, and an air supply valve 32, and amplifies the back pressure of the nozzle 2 and outputs the load A as an output pressure Pout.
This is a control relay that outputs to 4 is a feedback bellow to which the output air pressure Pout of the control relay 3 is input. 5 is a means for feeding back the force signal of the feedback bellows 4, and in this case, the movable piece 11 is also used. A lever 6 has one end connected to the exhaust valve 31 of the control relay 3 and the other end facing one end of the movable piece 11. 7 is a spring provided between the lever 6 and one end of the movable piece 11.

In the above configuration, the input signal current Iin is input. Now, due to the input signal current Iin, the movable piece 11
Suppose that the nozzle 2 is displaced in the direction of closing the nozzle 2. The nozzle back pressure P _N increases, is amplified by the movement of the exhaust valve 31 and the air supply valve 32 in the control relay 3, and output pressure is output. On the other hand, the same pressure as the output pressure Pout is input to the feedback bellow 4, which presses the movable piece 11 and acts in the direction of opening the gap with the nozzle 2. Thus, the above operation is repeated to achieve equilibrium corresponding to the input signal current Iin.

On the other hand, nozzle back pressure P _N control relay 3
In response to the input to The operation is repeated to balance the input signal current Iin. That is,
As shown in the block diagram of FIG. 4, a minor feedback loop B is formed and contributes to stabilizing the entire loop. Therefore, a device with good system stabilization properties can be obtained.

(Problems to be Solved by the Invention) However, in such a device, accuracy is required for the mounting position of the spring 7 between the movable piece 11 and the lever 6. If the spring 7 is misaligned in the axial direction, the spring 7
The body may bend in the sitting position or become bent into a dogleg shape. Further, if there is a deviation in the axial direction of the spring 7, the initial compressive force of the spring 7 will differ, and in some cases, there is a risk that the stress will exceed the allowable stress value of the spring 7 during operation. If the lever 6 and the movable piece 11 are to be positioned accurately, the cost will increase.

The present invention solves this problem.

An object of the present invention is to provide an electro-pneumatic converter with a simple configuration that does not require precision in the positional relationship between the flapper and the control relay, is inexpensive, and has good stabilization characteristics.

(Means for solving the problem) In order to achieve this object, the present application provides a driving means for driving a flapper in response to an input current in an electro-pneumatic converter that controls pneumatic output in response to an input current. a nozzle that is provided opposite to one end of the flapper and forms a nozzle flapper mechanism with the one end of the flapper; a control relay that amplifies the back pressure of the nozzle and outputs it as output air pressure; and an output air pressure of the control relay. a feedback bellow to which the same pressure is input; a feedback means for feeding back the force signal of the feedback bellow to the input side of the flapper; one end connected to the exhaust valve of the control relay and the other end connected to the A lever disposed opposite to one end of the flapper, and a magnetic means provided on at least one of the opposing portions of the lever and the flapper to repel or attract the opposing portions of the lever and the flapper. This is a configuration of a characteristic electro-pneumatic converter.

(Function) In the above configuration, when an input signal current is input, the flapper is displaced by the input signal current. When the nozzle is displaced in the direction of closing, the nozzle back pressure increases, is amplified in the control relay, and output pressure is output. On the other hand, the same pressure as the output pressure is input to the feedback bellow, which presses the flapper and acts in the direction of opening the gap with the nozzle. The above operation is then repeated to balance the input signal current.

On the other hand, by inputting the nozzle back pressure to the control relay, the exhaust valve of the control relay is moved, and the lever is actuated in the direction of opening the gap with the nozzle via magnetic means. The above operation is then repeated to balance the input signal current.

Examples will be described in detail below.

(Embodiment) FIG. 1 is an explanatory diagram of the main part configuration of an embodiment of the present invention.

In the figure, the same symbols as in FIG. 3 indicate the same functions.

Reference numeral 8 denotes a magnetic means provided on at least one of the opposing parts of the lever 6 and the flapper to repel or attract the opposing parts of the lever 6 and the flapper, and in this case, a magnet is used. In addition,
In this case, the movable piece 11 functions as the flapper.

In the above configuration, for example, nozzle 2
When δ between and flapper 11 increases, nozzle back pressure P _N decreases, and therefore exhaust valve 31 of control relay 3 is displaced upward in FIG. 1. Therefore, the gap δ between the nozzle 2 and the flapper 11 becomes smaller, and the magnetic force between the magnets 8 becomes larger, so the flapper 11 is displaced upward in the figure and the distance between the nozzle 2 and the flapper 11 is reduced. In other words, negative feedback is caused by a minor loop. Negative feedback is similarly applied when the distance between the nozzle 2 and the flapper 11 becomes smaller.

In this case, since the magnetic means is provided between the lever 6 and the flapper 11, it is not necessary to make the mounting position of the lever 6 and the flapper 11 accurate as in the conventional example, and the initial There is no risk that the compressive force will differ or that the spring 7 will exceed its allowable stress value during operation. Therefore, with a simple configuration, it is possible to obtain an electro-pneumatic converter that does not require precision in the positional relationship between the flapper and the control relay, is inexpensive, and has good stabilization characteristics.

FIG. 2 is an explanatory diagram of the main part configuration of another embodiment of the present invention.

In this embodiment, the magnet 8 is attached only to the lever 6. Note that it is of course possible to attach it only to the movable piece 11.

In addition, in the above-mentioned embodiment, a torque motor was used as a means for driving the movable piece 11, but the present invention is not limited to this.
For example, the movable piece may be driven using a piezoelectric element or the like; in short, any means for driving the movable piece 11 may be used.

(Effects of the Invention) As explained above, the present invention provides an electro-pneumatic converter that controls pneumatic output in response to an input current, including a driving means for driving a flapper in response to an input current, and one end of the flapper. a nozzle that is provided opposite to the flapper and constitutes a nozzle flapper mechanism with one end of the flapper; a control relay that amplifies back pressure of the nozzle and outputs it as output air pressure;
a feedback bellow to which the same pressure as the output air pressure of the control relay is input; a feedback means for feeding back a force signal of the feedback bellow to the input side of the flapper;
a lever having one end connected to the exhaust valve of the control relay and the other end facing one end of the flapper; and a lever provided on at least one of the opposing portions of the lever and the flapper, the lever and the flapper facing each other. Since the electro-pneumatic transducer is characterized in that it is equipped with a magnetic means for repelling or attracting the part that is moving, that is, since the magnetic means is provided between the lever and the flapper, as in the conventional example, There is no need to make the mounting positions of the lever and flapper accurate, and there is no risk that the initial compression force will be different or that the spring will exceed the allowable stress value during operation, unlike conventional springs. Therefore, the simple configuration does not require precision in the positional relationship between the flapper and the control relay.

Therefore, according to the present invention, it is possible to realize an electro-pneumatic converter with a simple configuration, which does not require precision in the positional relationship between the flapper and the control relay, and which is inexpensive and has good stabilization characteristics.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main part configuration of an embodiment of the present invention,
FIG. 2 is an explanatory diagram of the main part configuration of another embodiment of the present invention,
FIG. 3 is an explanatory diagram of the configuration of a conventional example that has been generally used, and FIG. 4 is a block diagram of FIG. 3. 1... Torque motor, 11... Movable piece, 2...
Nozzle, 3... Control relay, 30... Diaphragm, 31... Exhaust valve, 32... Air supply valve,
4... Feedback bellow, 5... Feedback means, 6... Lever, 7... Spring, 8
……magnet.

Claims (1)

[Scope of utility model registration request] In an electro-pneumatic converter that controls pneumatic output in response to an input current, a drive means that drives a flapper in response to an input current, and a nozzle flapper mechanism provided opposite to one end of the flapper and connected to one end of the flapper and a nozzle flapper mechanism. a control relay that amplifies the back pressure of the nozzle and outputs it as output air pressure, a feedback bellow that receives the same pressure as the output air pressure of the control relay, and a control relay that amplifies the back pressure of the nozzle and outputs it as output air pressure; feedback means for feeding back a signal to the input side of the flapper; a lever having one end connected to the exhaust valve of the control relay and the other end facing one end of the flapper; and the lever and the flapper facing each other. An electro-pneumatic converter comprising magnetic means provided on at least one of the parts for repelling or attracting the lever and the opposing part of the flapper.