JPH04264Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is an electric signal that converts electrical signals into air signals.
Regarding empty converters.

Conventionally, electro-pneumatic converters have been implemented based on the principle of using coils as shown in FIGS. 1 and 2. The electro-pneumatic converter shown in FIG. 1 generates an attractive force (repulsive force) between the coil 1 and the permanent magnet 2 by applying an input current to the coil 1, thereby changing the gap between the flapper 3 and the nozzle 4. The supply (air) pressure 5 passes through the throttle 6 and flows out from the nozzle 4, but at the time of exit, the back pressure is changed due to the gap between the flapper 3 and the nozzle 4, and the output (air) pressure 7 is adjusted according to this back pressure. Derive. The force due to this back pressure and the attractive force due to the coil and permanent magnet are both balanced to obtain an output pressure according to the input signal. The basic principle of the electro-pneumatic converter shown in FIG. 2 is the same as that shown in FIG. In addition, the structure is different in that the flapper 3 is pressed.

However, all of the above-mentioned conventional electro-pneumatic converters use coils, and the attraction force of this coil is relatively weak. It has the disadvantage that it has to be large, making it structurally large. In addition, coils, permanent magnets, flapper levers,
The number of parts increases due to the need for bellows, etc., and from this point of view as well, it has the disadvantage of becoming complex and large. Furthermore, since it has many mechanical parts whose characteristics are not linear, it is difficult to expect high performance.

In view of the above, the purpose of this invention is to eliminate the drawbacks of conventional devices and provide a high performance, compact, and inexpensive electro-pneumatic transformer.

In order to achieve the above object, the electro-pneumatic converter of this invention is made by pasting piezoelectric elements on the front and back sides of a thin metal plate with a hollowed out center, one end of which is fixed, and an input voltage is applied between the thin metal plate and the piezoelectric element. It is characterized in that a voltage-displacement conversion element whose other end is displaced by application of voltage is used as a flapper.

This invention will be explained in detail below with reference to embodiments shown in the drawings.

FIG. 3 is a connection diagram of an electro-pneumatic converter showing an embodiment of this invention. In the figure, 11 is a voltage-displacement conversion element used as a flapper. As shown in FIG. 4, the voltage-displacement conversion element 11 is constructed by pasting ceramic piezoelectric element plates 13 and 14 on the front and back sides of a thin metal plate 12 with a hollowed out central portion 12a, and an end portion 12b of the thin metal plate 12. ,12
c is exposed. One tip 1 of the thin metal plate 12
2b is fixed, and the other end 12c faces the nozzle 15. The input signal voltage Ei is applied to the piezoelectric element plates 13 and 14 of the voltage-displacement conversion element 11.
6 and are commonly connected to an amplifier 16 to be amplified and applied. The piezoelectric element plates 13 and 14 are electrically connected in parallel and are grounded via the thin metal plate 12. On the other hand, the supply pressure 17 is applied to the nozzle 15 through a throttle 18, and the back pressure from the nozzle 15 is amplified approximately ten times by a pilot valve 19. An output pressure 20 is derived from the pilot valve 19, and the output pressure is connected to a pressure sensor 21 so as to be applied thereto. The pressure sensor 21 is configured to convert the applied pressure into a voltage corresponding to the applied pressure, and to feed back the voltage corresponding to the output pressure through the resistor R.

Now, when input voltage Ei is applied to the input terminals 22a and 22b in FIG. A voltage amplified by an amplifier 16 is applied to. By the way, as shown in FIG.
uses piezoelectric elements inside each plate that are polarized in the direction of the arrow from bottom to top in the thickness direction, that is, in the same direction. Therefore, the piezoelectric element plate 13 and
Voltages having opposite polarities are applied to the piezoelectric element plate 14 in the polarization direction. Therefore, when the amplified voltage from the amplifier 16 is applied, the piezoelectric element plate 13 is strained so as to expand, and the piezoelectric element plate 14 is strained so as to contract, depending on the applied voltage. As a result, the voltage-displacement conversion element 11 receives a displacement of Δd.
Due to this displacement caused by the voltage change, the tip 12c of the thin metal plate 12 closes the mouth of the nozzle 15, and the nozzle back pressure increases. This back pressure is further amplified by the pilot valve 19, increasing the output pressure. The output pressure is converted into an electrical signal by the pressure sensor 21, which is applied to the input signal circuit through the resistor R and compared with the input voltage Ei, so that the signal from the pressure sensor 21 and the input signal voltage Ei are
The deviation is applied to the amplifier 16, amplified by the amplifier 16, and applied to the voltage-displacement conversion element 11 again. While the input signal voltage Ei is greater than the signal from the pressure sensor 21, the displacement Δd is encouraged to increase and the output pressure also increases. Input signal voltage Ei
When the voltages from the pressure sensor 21 become equal, the output pressure correction operation ends, and the output pressure 20 corresponding to the input signal voltage Ei can be obtained.

In the above embodiment, the thin metal plate 12 is hollowed out in order to make the spring constant of the thin metal plate as small as possible and to increase the piezoelectric constant.

In addition, it is desirable to use a thin metal plate with a coefficient of expansion as small as possible to reduce the influence of temperature.

Furthermore, by widening the width of the voltage-displacement conversion element, the influence of the reaction force of the flapper due to the air jetted from the nozzle can be reduced.

As described above, according to the electro-pneumatic converter of this invention, piezoelectric elements are pasted on the front and back sides of a thin metal plate with the center hollowed out, one end is fixed, and an electric current is applied to the thin metal plate and the piezoelectric element. Since it uses a voltage-displacement element whose other end is displaced according to the voltage as a flapper, there is no need to use a coil like in conventional devices, and therefore there is no need to use a long lever, making it easy to use a converter. Can be made extremely compact.

Furthermore, the circuit that converts the output pressure into an electrical signal using a pressure sensor, the circuit that feeds back the electrical signal to the input side, and the circuit that amplifies the input signal voltage and applies it to the voltage-displacement conversion element can all be configured with electronic circuits. from,
From this point of view, it is possible to miniaturize the circuit by converting it into an IC, etc.
There is an advantage in that the electric-pneumatic conversion characteristics are greatly improved compared to conventional ones, by ensuring linear characteristics through electronic circuitry, and by reducing errors due to the influence of temperature due to fewer mechanical parts.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams showing a conventional electro-pneumatic converter, Fig. 3 is a connection diagram showing an electro-pneumatic converter according to an embodiment of this invention, and Fig. 4 is a diagram showing the implementation of Fig. 3. FIG. 4A is a plan view, FIG. 4B is a cross-sectional view of the same, and FIG. 5 is a diagram showing a voltage-displacement conversion element used in the example. It is a figure showing a state. 11... Voltage-displacement conversion element, 12... Metal thin plate, 13, 14... Piezoelectric element plate, 15... Nozzle, 16... Amplifier, 17... Supply pressure, 18...
Throttle, 19... Pilot valve, 20... Output pressure,
21...Pressure sensor.

Claims (1)

[Scope of utility model registration request] It consists of an electrical input signal source and a piezoelectric element pasted on the front and back sides of a thin metal plate with a hollowed out center, one end of which is fixed, and the voltage from the electrical input signal source is applied to the thin metal plate and the piezoelectric element. A pneumatic system including a voltage-displacement conversion element whose other end is displaced according to the voltage, a nozzle that uses this voltage-displacement conversion element as a flapper, an output pressure according to the supply pressure and the back pressure between the nozzle and the flapper; An electro-pneumatic converter comprising a circuit that converts the output pressure of a pneumatic system into an electrical signal and feeds it back to the electrical input signal source.