JPS595161B2 - pressure generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure generator that generates a pneumatic output signal in response to an electrical human power signal.

FIG. 1 is an explanatory diagram of the configuration of a conventional example generally used in conventional equipment.

In the figure, 1a is a human electric signal, 2a is a current-displacement converter, and 3a is a balance lever whose middle part is supported by a fulcrum O and to which displacement from the current-displacement converter 2a is applied.

4a is arranged opposite to the other end of the lever 3a, and
This is a nozzle that constitutes a nozzle-flapper mechanism.

41a is a supply air source.

5a is an air amplifier that amplifies the back pressure Pn of the nozzle 4a.

6a is a feedback bellows arranged opposite to lever 3a.

A part of the output of the air amplifier 5a is introduced into the feedback bellows 6a and outputted as an output air pressure 7a.

8a is a zero adjustment spring mechanism. In the above configuration, when the human-powered electric signal 1a is manually applied, a displacement corresponding to the magnitude thereof is applied to one end of the lever 3a by the current-displacement converter 2a.

Corresponding to this displacement, the gap G between the other end of the lever 3a and the nozzle 4a changes.

This change in the gap G causes a change in the back pressure Pn of the nozzle 4a, and this back pressure Pn is amplified by the air amplifier 5a and output as an output air pressure 7a, and a portion is fed back to the feedback bellows 6a.

In the balance lever 3a, the current-displacement converter 2a
The balance lever is kept in balance in a state where the force due to the feedback bellows 6a and the force due to the feedback bellows 6a are balanced.

As described above, the output air pressure 1a corresponding to the input electrical signal 1a is output.

However, since such a device uses a nozzle flapper mechanism, as will be described later, the pressure is zero.
Due to its characteristics, nonlinearity errors in the vicinity become large.

Further, the nozzle-flapper mechanism generally has a high gain.

That is, the nozzle back pressure Pn changes from the supply air pressure 41a to approximately O.
The nozzle gap G until the atmospheric pressure is reached is usually 0.1 to 0.
There are only two strokes.

Therefore, if an attempt is made to obtain a device with a resolution of 0.01%, the displacement of the flapper will be on the order of 0.02 μm.

Such items may suffer from vibrations, subtle changes in ambient temperature, etc.
Even minute hysteresis etc. can have a large influence on the characteristics as errors and cannot be used.

If an attempt is made to lower the gain in order to set the loop gain of the entire device to an appropriate value, the non-linear error near the pressure O becomes worse and the output pressure becomes less close to the pressure O.

Therefore, it is easy to oscillate, the device lacks stability, and offset is likely to occur.

Further, the flapper is susceptible to vibrations in the direction of movement and its output is likely to fluctuate.

In addition, in practical use, there is often a need to use a pressure close to pressure O, such as the pressure of LoomH20.

The present invention solves this problem.

An object of the present invention is to provide a pressure generator that has good linearity in the vicinity of the output air pressure O, has no offset, has high vibration resistance, and has a highly stable system.

In order to achieve this purpose, a pneumatic converter converts an output pneumatic signal into an electric signal in response to an output pneumatic signal, and a differential amplifier differentially amplifies the electric signal from the pneumatic converter and the input electric signal. a servo motor section driven by the output of the differential amplifier section, and a valve mechanism that generates an air output signal in response to the amount of rotation of the servo motor section, the valve mechanism being directly connected to the tapered section. A valve seat in the shape of a venturi tube consisting of a pipe portion and a widened end portion that is closed, a supply pipe provided in the valve seat on the widened end side of the widened portion, and a valve seat of the straight pipe portion or the widened portion. A pressure generator comprising an output pipe provided in a direction substantially perpendicular to the axis of the valve seat, and a substantially conical valve body inserted into and away from the valve seat from the tapered portion side. It is.

FIG. 2 is an explanatory diagram of the configuration of one embodiment of the present invention, and FIG.
FIG. 2 is a block diagram of FIG.

In the figure, 1 is a human electric signal, 2 is an output pneumatic signal 3
This is a pneumatic converter that converts the pneumatic signal into an electric signal in response to the pneumatic signal 3.
The differential inductance circuit 23 converts the displacement of 1 into an electric signal via a plate-shaped spring 22, and a preamplifier 24 amplifies the output of the differential inductance circuit 23.

Reference numeral 4 denotes a differential amplifier section that differentially amplifies the electric signals of the human power electric signal 1 and the air-electric conversion section 2.1.

Reference numeral 5 denotes a servo motor section including a servo motor 51 and a gear mechanism 52 driven by the output from the differential amplifier section.

Reference numeral 6 denotes a valve mechanism that generates an air output signal in accordance with the amount of rotation of the servo motor section 5.

61 is a threaded portion 521 provided on the output shaft of the gear mechanism 52
The tip portion 611 is a substantially conical valve body screwed into the valve body.
In this case, the angle is determined by appropriately selecting the rate of change in the area of the entrance with respect to the movement of the valve body, which will be described later.

62 is a substantially cylindrical valve seat, 621 is a conical tapered part that tapers downward in the figure, 622 is a straight pipe part, 623
is a widening part that expands into a conical shape as it moves toward the bottom of the figure.

63 is a lid provided on the open end side of the wide part, 64 is the lid 6
3, is a supply pipe arranged on the axis of the valve seat 62, and is supplied with a constant supply air pressure Ps.

Reference numeral 65 designates an output pipe that is also provided on the lid 63 and arranged perpendicular to the axis of the valve seat 62.

66 is a coiled spring that pulls the valve body 61 against the valve seat 62 without rotating.

The valve body 61 moves in the direction of arrow X in response to the amount of rotation of the servo motor section 50, and the distal end portion 611 is inserted into the tapered portion 621 so as to be freely movable towards and away from it.

7 is an output tank, 8 is a pipe connecting the valve 6, the bellows 21, and the output tank 7, and 81 is a throttle provided in the pipe 8 near the output tank 7.

In the above configuration, the output pneumatic signal 3 converted into an electric signal by the pneumatic conversion section 2 is sent to the differential amplifier section 4 and compared with the human-powered electric signal 1.

If there is a positive or negative deviation from the human electric signal 1,
The difference amount is amplified by the differential amplifier section 4.

Depending on the polarity of the electrical signal amplified by the differential amplifier section 4, the DC servo motor 51 rotates clockwise or counterclockwise, and the gear mechanism 52 is driven.

As the carrier mechanism 52 rotates, the valve body 61 moves in the direction of the arrow X shown in FIG. 2, and the gap between the valve body 61 and the valve seat 62 changes.

Due to this change in the gap, the back pressure within the valve seat 62 changes, and this back pressure is taken out as the output air pressure signal 3 via the pipe 8 → the output tank 7.

In the above, each component is configured to operate to reduce the deviation.

That is, for example, if the output air pressure signal 3 is lower than the human power electric signal 1, the servo motor 51 and the gear mechanism 5
2 operates to move the valve body 61 downward in the diagram of FIG. 2, the gap between the valve body 61 and the valve seat 62 becomes smaller, and the output air pressure signal 3 increases.

If the output pneumatic signal 3 is higher than the input electrical signal 1, the opposite operation is performed.

Thus, the above-described operation is repeated continuously, and an output air pressure signal 3 corresponding to the human-powered electrical signal 1 is obtained.

In this case, as a displacement-air pressure converter, the valve body 61 is configured to be able to move freely toward and away from the tapered portion 621 side of the valve seat 62 in the shape of a ventilate tube, and a constant pressure is supplied from the axial direction of the valve seat 62. An output pipe 65 that supplies air pressure and is provided at right angles to the axis of the valve seat of the straight pipe section 622 or the diverging section 623.
A valve mechanism designed to extract the output air pressure signal 3 was used.

In such a valve mechanism, the supply air pressure Ps introduced from the supply pipe 64 is taken out from the output pipe 65 as the output air pressure signal 3.

As shown in FIG. 4, the output air pressure signal 3 moves the valve body 61 upward from the valve seat 62 from its close contact with the valve seat 62.
2, the supply air pressure Ps gradually decreases, eventually dropping to below atmospheric pressure, and below atmospheric pressure, the slope gradually becomes gentler.

Therefore, compared to the characteristic curve of the nozzle flapper mechanism commonly used in the past, which is shown by the dotted line in FIG. It becomes wider, and the non-linear error especially near the output pressure of 0 becomes smaller.

Next, now, t: effective length of the valve mechanism 6 of the present invention, X: Stroke α: 1/2 of the apex angle of the valve body 61 d: Inner diameter of valve seat 62 Then, the valve mechanism 6 can be expressed in principle as shown in FIG.

Therefore, 7=x0sinα The average circumferential length Cav is the flow area A=l °Cav=πx sinα(d−xsinα
If the area change rate X with respect to cosα last stroke X is small, that is, by changing the apex angle (2α) of the valve body 61,
Rate of change (gain) in valve opening area with respect to displacement of valve body 61
can be changed arbitrarily.

In addition, since the valve body 61 and the tapered portion 621 are mutually smoothly tapered, the air flow is not disturbed.
Therefore, a stable output air pressure signal 3 is obtained without noise caused by air turbulence being added to the output air pressure signal 3.

Generally, in order for a servo system to have a small offset and operate stably without oscillation, it is necessary to set the loop gain to an appropriate value.

Therefore, if the gain of the displacement-air conversion mechanism (valve mechanism) can be arbitrarily selected, the loop gain can be set to an appropriate value.

Nozzle generally used as a displacement-air pressure conversion mechanism
The flapper mechanism has a high gain, and the linearity is inherently poor when the output air pressure is around 0.

When trying to lower the gain in order to set the loop gain of the servo system to an appropriate value, see Figure 4 A-+B-.
*As shown in C, linearity becomes worse and
It has the disadvantage that the output pressure approaches zero or disappears.

In the displacement-air pressure conversion mechanism (valve mechanism) of the device of the present invention, as mentioned above, the gain can be changed arbitrarily, and the linearity does not deteriorate, so the loop gain of the entire system can be appropriately selected. At the same time, since the variation in gain at each setting point is small, the output air pressure signal can be obtained with good stability as a servo system from O to a predetermined pressure.

In addition, in the above-mentioned embodiment, it was explained that the pneumatic converter 2 is composed of a bellows 21, a spring 22, a differential inductance circuit 23, and a preamplifier circuit 24.
The present invention is not limited to this, as long as it has the function of converting air pressure into an electrical signal.

Further, the output tank 7 may not be provided depending on the load condition.

Further, in the valve mechanism 6, although it has been described that the output pipe 65 is provided in the lid 63, it goes without saying that it may be provided in the straight pipe portion 622 or the diverging portion 623.

As explained above, according to the present invention, it is possible to reduce the nonlinearity error of the output air pressure with respect to the human-powered electric signal, especially in the vicinity of 0 output air pressure, and to obtain an appropriate loop gain, thereby preventing oscillation. A stable device is obtained.

Furthermore, the differential amplifier section, the servo motor section, and the displacement-pressure conversion section (valve mechanism) constitute a forward circuit, and the pneumatic conversion section constitutes a feedback circuit. As a result, the servo motor section with integral characteristics is used. Since it is, it is possible to remove off-sera)k.

In addition, since the position of the valve body of the displacement-pressure converter is held by the threaded part provided on the output shaft of the servo motor part,
You can get something that is strong against vibration.

Furthermore, since an electrical signal is used to match the output signal to the input signal, a higher resolution can be obtained than in the case of using an air signal, and a greater practical effect can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a conventional example commonly used, Fig. 2 is an explanatory diagram of the configuration of an embodiment of the present invention, Fig. 3 is a block diagram of Fig. 2, and Fig. 4 5 is a diagram illustrating the characteristics of the valve mechanism of the present invention and a nozzle flapper mechanism commonly used in the prior art, and FIG. 5 is a diagram illustrating the principle of the valve mechanism. 1... Human electric signal, 2... Air conversion section, 3... Output air pressure signal, 4... Differential amplifier section, 5... ...Servo motor section, 6...
... Valve mechanism, 61 ... Valve body, 62 ...
・Valve seat, 621...Tapered part, 622...
・・・Straight pipe part, 623... Wide end part, 64...
... Supply pipe, 65 ... Output pipe.

Claims (1)

[Claims] 1. A pneumatic converter that converts an output air pressure signal into an electric signal, a differential amplifier that differentially amplifies the electric signal from the pneumatic converter and the human-powered electric signal, and the differential amplifier. a servo motor section driven by the output of the servo motor section, and a valve mechanism that generates an air output signal in response to the amount of rotation of the servo motor section, and the valve mechanism has a tapered section, a straight pipe section, and an enlarged end side. a valve seat in the shape of a Venturi tube consisting of a diverging portion, a supply pipe provided on the valve seat on the enlarged end side of the divergent portion, and a direction substantially perpendicular to the axis of the valve seat of the straight pipe portion or the divergent portion; A pressure generator comprising: an output pipe provided in the tapered portion; and a substantially conical valve body inserted into the valve seat from the tapered portion side so as to freely move toward and away from the valve seat.