JPS61268884A - Pressure adjustor for hydraulic pressure - Google Patents

Abstract

PURPOSE:To remove the expendable supplies and facilitate maintenance by installing a strain gauge for outputting a voltage difference in proportion to the fluid pressure and controlling the drive and stop of a pressure motor by opening and closing a power transistor by a Schmidt circuit according to the output. CONSTITUTION:A pressure motor 1 for compressing air for railway car, etc. is supplied with electricity from a stringing 2 through a pantagraph 3 and an electromagnetic contactor 34. In this case, a strain gauge 21 consisting of strain gauges 22 arranged in bridge form on one surface of a metal bellowphram 23 in a pressure case 7 into which the pressure of the compressed air is supplied from the pressure motor 1 is installed. The voltage difference in proportion to the pheumatic pressure is taken out form the output lines 24C and 24D of the strain gauge 21, and the voltage in proportion to the voltage difference is outputted from a differential amplifying circuit including an operation amplifier A1, and the variation quantity of the output is detected by a Schmidt circuit including an operation amplifier A2, and a power transistor Tr12 is driven by the output, and the electromagnetic contactor 4 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pressure regulator for fluid pressure, and particularly to a pressure regulator used in a pressurizing motor for compressing air in a railway vehicle or the like.

[Prior art JtI & Figures 5 and 6 are, for example, published by Japanese Patent Publication No. 45-14454.
The conventional fluid pressure regulator shown in the publication is used in a pressurizing motor for compressing air in railway vehicles, etc. In Figure 1, (1) shows the pressurizing motor constituting the fluid pressure regulator. The driving voltage is obtained through the overhead wire (2) and the pantograph (3). (4) is an electromagnetic contactor, which is provided between the pressure motor (1) and the pantograph (3), and has a contact α° (15) that directly opens and closes the power supply circuit of the pressure motor (1); It consists of an excitation coil (14) for opening and closing this contact (15), (5) and (6) are driven according to the pressure of compressed air from a pressurizing motor (1), for example. These are proximity switches such as Hall elements, and are driven by different pressures P 1 and P 2 , which will be described later. This proximity switch (5) 1 (
6) The drive If mechanism is constructed as shown in Fig. 6, and includes a piston rod (8) slidably provided in the pressure case (7).
and a piston rod (8) built into the pressure case (7).
a piston spring (9) that biases the piston in the direction of burial (bottom of the drawing); and a piston seal (10) that is biased by the spring (9) and fixed inside the pressure case (7) to support the piston rod (8). ), an air intake port (11) formed on one end surface of the pressure case (7), and a proximity switch (5) provided at a predetermined position on the protruding end of the piston rod (8), respectively.
Proximate object (12), such as a permanent magnet, corresponding to (6)?
It consists of (13).

(Tri) is a common emitter transistor whose base is connected to the output terminal of the proximity switch (5), and (CR1) is a transistor whose output terminal of the proximity switch (6) is connected to the date and whose cathode is connected to the collector of the transistor (Tri). A connected thyristor. Proximity switch (5) and (/(6)
) is grounded. (Ry) is
This is an auxiliary relay having one end connected to the 7/- wire of the thyristor and a contact (16) connected in series to an electromagnetic contactor (Ll) to be described later. (DZI) and (DZ2) are Zener diodes connected in series between the other end of the auxiliary relay (Ry) and ground. The other input terminal of the proximity switches (5) and (6) is a Zener diode (D Z 1
) and (D Z 2 ). (R1)
, (R2) are resistors, which are connected between an electromagnetic contactor (Ll) and an auxiliary relay (Ry), which will be described later, and between both terminals of a V Zener diode (DZl), respectively.
(Ll) is the aforementioned contact (
16) and is an electromagnetic contactor having a contact (17). The contact (17) is connected between electric fi (DC+) and ground via the excitation coil (14) of the electromagnetic contactor (4).

Next, the operation will be explained. Now, set the air pressure of the fluid pressure regulator as P 1 eP 2 (kg/am2) (
However, Pi < P2). First pressurize motor (1)
If the air pressure just before driving the piston rod (8) is below P1, the piston rod (8) in FIG. 6 is sufficiently buried. Therefore, even when the power is turned on, the proximity switches (5) and (6) are not driven, and the transistor (Tri) and thyristor (CRI) are not driven.
) also does not operate, since the coil of the auxiliary relay (Ry) is demagnetized and the contact (16) is closed.
A voltage is applied to the electromagnetic contactor (Ll). Therefore, when the contact (17) is closed and voltage is applied to the electromagnetic contactor (4), the excitation filter (14) closes the contact (15) and the pressurizing motor (1) is driven. Ru.

The air pressure that gradually increases due to the drive of the pressurizing motor (1) pushes against the piston spring (9) and pushes the piston seal (
10) and push up the piston rod (8). If the proximal bodies (12) and (13) are positioned and fixed at predetermined positions, when the air pressure reaches Pl, the proximal body (12)
corresponds to the proximity switch (5), and the proximity switch (5) operates. Therefore, a voltage is applied to the base of the transistor (Tri), and the transistor (Tri) is turned on.

However, since the proximity switch (6) is not working, the sirisk (CR1) remains off and the auxiliary relay (
Ry) maintains a demagnetized state. For this reason, the contact (16
) remains closed, the pressurizing motor (1) continues to drive, and the air pressure increases further.

When the air pressure reaches P2*, the piston rod (8) protrudes further and the proximal body (13) corresponds to the proximity switch (6). Therefore, the proximity switch (6) is turned on, a voltage is applied to the data F of the thyristor (CRI), and the thyristor (CRI) is turned on. At this time, the transistor (T
Since ri) is on as mentioned above, the auxiliary relay (
The fill of Ry) is excited by a current flowing through it. Therefore, the contact (16) is released and demagnetizes the electromagnetic contactor (Ll), which releases the contact (17), thereby turning off the electromagnetic contactor (4) and turning off the pressurizing motor (1). make it stop.

When compressed air is consumed by opening and closing a single-panel door, etc., and the pressure drops below P2, the proximity switch (6) and the proximity object (
13) is separated and no voltage is applied to the thyristor (CRI), but the thyristor (CR1) remains on.

When the air pressure further decreases to below P1, the proximity switch (5) and the proximity body (12) are separated, and at this moment, no voltage is applied to the base of the transistor (Tri). Therefore, as the transistor (Tri) turns off, the thyristor (CRI)
is also turned off, the coil of the auxiliary relay (Ry) is demagnetized, the contact (16) is closed again, and the pressurizing motor (1) starts driving.

By repeating the above operations, the air pressure obtained by the pressurizing motor (1) is always maintained between Pl and R2. The air pressures Pi and P2 are set using the piston rod (8
), the proximal bodies (12) and (13) are screwed and fixed to
This is done by loosening the screws as appropriate and sliding them on the piston rod (8).

[Problem to be solved by the invention 1 Since the conventional fluid pressure regulator is constructed as described above, each part must be replaced as the mechanically movable parts such as the piston rod wear out. There wasn't. In particular, the piston seal had poor durability and had to be replaced every two years. In addition, since the air pressure is set by adjusting the positional relationship between the proximity switch and the nearby object, the accuracy is poor and
There was a problem in that adjustment also required a considerable amount of time.

Furthermore, since the contacts of the electromagnetic contactor apply a relatively large current to the appropriate locations, there is a problem in that maintenance is also required.

This invention was made to solve the above-mentioned problems, and aims to provide a fluid pressure regulator that eliminates consumable parts and allows air pressure to be set easily and accurately. do.

[Means for Solving the Problems] A fluid pressure regulator according to the present invention includes a strain gauge that outputs a voltage difference proportional to the fluid pressure, and a strain gauge that outputs a voltage proportional to the output voltage difference of the strain gauge. a dynamic amplifier circuit, a 91271 circuit that detects the output voltage of this differential amplifier circuit,
The device includes a power transistor driven by the output of the Schmitt circuit, a contactor driven by the power transistor, and a pressurizing motor whose driving and stopping are switched by the contactor.

[Operation] In this invention, the strain gauge supplies a voltage output proportional to the fluid pressure to the Schmitt circuit without using any moving parts, and the Schmitt circuit opens and closes the power transistor to drive the pressurizing motor and Toggle stop. Furthermore, the air pressure is set by changing circuit constants, ie, resistance values, in the Schmitt circuit.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
In the figure and FIG. 2, symbols (1) to (4).

(7), (11), (14) and (15) are shown in FIG.
This is similar to the conventional device shown in FIG. (21)
is a strain gauge, and is constructed as shown in FIG. (22) is a strain gauge arranged in a bridge shape, and is fixed on the surface opposite to the air intake port (11) of a metal bellows frame (23) fixed in the pressure case (7). At the connection point of each strain gauge (22), a power source M (24
A)? A power supply input line (24B) and output lines (24C) and (24D) connected to the common terminal C are connected. Therefore, when compressed air pressure is applied from the air intake port (11), the metal bellofram (23) is deflected, and the strain gauge (22) fixed to it is distorted in accordance with the air pressure, resulting in a change in resistance value. Therefore, connect the power input line (24A) to the bridge-connected strain gauge (22).
.

If voltage is applied through (24B), output line (24B)
4C) and (24D), a voltage difference proportional to the air pressure is generated.

(A 1 ) and (A 2 ) are operational amplifiers configured as rct'. The operational amplifier (A1) is connected to the resistor (R11
), (R12) to the output line (2) of the strain gauge (21).
4C).

(24D) is input, the resistor (R11) side is fed back via the resistor (R13), and the resistor (R12
) side is connected to the common terminal (C) via a resistor (R14). The operational amplifier (A1) is connected to the resistor (R11)
~ (R14) constitutes a differential amplifier circuit, and the strain gauge (
21) is amplified to a predetermined voltage value corresponding to the voltage difference. As a result, the output voltage V (A1) of the operational amplifier (A1) in the differential amplifier circuit becomes proportional to the value of the air pressure P, as shown in the fJS3 diagram.

The operational amplifier (A2) outputs the output voltage V (A1) of the differential amplifier circuit, that is, the operational amplifier (A1), through the resistor (R15).
This input terminal is connected to a variable resistor (V R1
) is connected to the terminal (isv>) and is fed back via the capacitor (C1).
The other input terminal of A2) is fed back via a variable resistor (V R2) and is connected to the common terminal (C) via a resistor (R16).

The operational amplifier (A2) has resistors (R15) and (R16)
.

A Schmitt circuit is constructed within the variable resistors (V R1), (V R2) and tlcontin+ (C1), and the fourth
It has hysteresis characteristics as shown in the figure.

Voltage value V2 in this hysteresis characteristic. Vl is variable resistance n(VRI)-(VH2)I:! Therefore, the air pressure P2 can be adjusted by variable resistance a (V R1), and the air pressure P1 can be adjusted by variable resistance 11 (V R2).
Each can be set.

The output voltage V (A2) of the operational amplifier (A2) is
17) to the base of the transistor (Trll), and the voltage terminal (+15V) is applied to the base of the transistor (Trll) through the
l>, and the emitter of the transistor (Trll) is connected to the mercury contact relay (Rs).
It is connected to the common terminal (C) via. The contact (S) of the mercury contact relay (Rs) has a resistance of 1s (RlB),
(R19) is provided between a 100V I source terminal (DC terminal) and the base of a power transistor (Tr12) to be described later. The transistor (Trll) constitutes a power transistor drive circuit together with a mercury contact relay (Rs) and resistors (R17) to (R19).

(25) is a constant voltage generation circuit, and the terminal (DC+)
The power supply voltage (+15V), (-
15V) and a common voltage terminal (C) are generated and supplied to each circuit. , the power transistor (Tr12) is
The emitter is grounded via the excitation coil (14) of the electromagnetic contactor (4), and its collector is connected to jl (DC+), forming a power transistor output circuit together with the power transistor drive circuit. The emitter of the power transistor (Tr12) is connected to the excitation coils (not shown) of other multiple electromagnetic contactors, and drives and controls multiple similar pressurizing motors in synchronization. explain. As before, the set air pressure value is P 1 rP 2 (kg/am”) (however,
Assuming that Pl<R2), the initial air pressure is less than P1, so the output voltage V(AI) of the operational amplifier (A1) is less than R1 as shown in FIG. At this time, the output voltage V (A2) of the operational amplifier (A2) is equal to the on-voltage v of the transistor (Trll) as shown in FIG.

Therefore, the transistor (Trll) is turned on, the coil of the mercury contact relay (Rs) is energized, and the contact (S
) is closed. Therefore, the power transistor (Tr12
) is closed, and the electromagnetic contact &(4> contact (
15) is closed, the pressurizing motor (1) is driven.

The air pressure P gradually increases and exceeds Pl, and the operational amplifier (
Even if the output voltage V (A1) of A1) exceeds ■1, the operational amplifier (A
Since the output voltage V (A2) of 2) remains at the ON voltage VO of the transistor (Trll) as shown in FIG. 4, the pressurizing motor (1) continues to drive.

When the air pressure P further increases and reaches R2, the output voltage V (AI) of the operational amplifier (A1) becomes ■2, and the output voltage V (A2) of the operational amplifier (A2) becomes 0 as shown in Figure 4.
■It becomes. Therefore, the transistor (Trll) is turned off, and by demagnetizing the coil of the mercury contact relay (Rs) and releasing the base circuit of the power transistor (Tr12), the contact (15) of the magnetic contactor (4) is released. ,
Stop the pressurizing motor (1).

Then, due to the consumption of compressed air, the air pressure P becomes less than R2, and the output voltage V (A1) of the operational amplifier (A1) becomes R2.
Even if the voltage is below, as long as it is V1 or higher, that is, the air pressure is 21 or higher, the output voltage V(A2) of the operational amplifier (A2) is maintained at Ov due to the hysteresis characteristics shown in FIG.

When the air pressure P further decreases to Pl, the output voltage of the operating amplifier (A1), that is, the input voltage V (AI) of the operational amplifier (A2) becomes Vl, and the output voltage V (A2) of the operational amplifier (A2) rises to vO. . Therefore, the transistor (Trll) is turned on again to drive the pressurizing motor (1). Hereafter, while repeating the above operation, pressurize motor (
1) Switch between operation and stop, and set the air pressure to P1.
The pressure is adjusted between ~P2.

The air pressures P 1 and P 2 are set by adjusting the variable resistors (V R2) and (V R1) as described above. It can be easily done by simply turning left and right.

In addition, in the above embodiment, the pressure regulator was used for compressed air in railway heavy vehicles, but it is not limited to this, and it is possible to use it as a pressure regulator for other target devices and other fluids. , it goes without saying that they have the same effect.

[Effects of the Invention] As described above, according to the present invention, a fluid pressure regulator is configured to include a strain dage that outputs a voltage difference proportional to the fluid pressure and a voltage proportional to the output voltage difference of this strain dage. a Schmitt circuit that detects the amount of change in the output voltage of this differential amplifier circuit, a power transistor driven by the output of this Schmitt circuit, a contactor driven by this power transistor, and It consists of a pressure motor that is supplied with power via a contactor, and achieves fluid pressure detection without mechanical consumable parts and output switching without contact parts, making maintenance and air pressure settings easy. effective.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a partial block diagram of a fluid pressure regulator according to an embodiment of the present invention, Fig. 2 is a sectional view showing the structure of the strain gauge shown in Fig. 1, and Fig. #3 and $4 are Characteristic diagrams of each operational amplifier of the differential amplifier circuit and Schmitt circuit in Figure 1,
FIG. MS5 is a circuit diagram partially showing a conventional fluid pressure regulator in block form, and FIG. 6 is a sectional view showing the proximity switch switching mechanism of FIG. 5. (1) is a pressure motor, (4) is an electromagnetic contactor (contactor),
(21) is a distortion 2-no, (AlH) is an operational amplifier that configures a differential amplifier circuit, (A2) is an operational amplifier that configures a Schmitt circuit, and (Tr12) is a power transistor. - or a corresponding portion.

Claims (4)

[Claims] (1) A strain gauge that outputs a voltage difference proportional to the input fluid pressure, a differential amplifier circuit that outputs a voltage proportional to the output voltage difference of this strain gauge, and a change in the output voltage of this differential amplifier circuit. A Schmitt circuit that detects the amount, a power transistor driven by the output of this Schmitt circuit,
A fluid pressure regulator consisting of a contactor driven by this power transistor and a pressure motor to which power is supplied via this contactor. (2) The fluid pressure regulator according to claim 1, wherein the strain gauge comprises a metal verofram and a strain gauge mounted on the metal verofram and connected to the bridge. (3) The fluid pressure regulator according to claim 1 or 2, wherein the Schmitt circuit is composed of an IC operational amplifier and has hysteresis characteristics. (4) The fluid pressure regulator according to any one of claims 1 to 3, wherein the Schmitt circuit has a variable resistor for changing its circuit constant.