JPH01129310A - Automatic set pressure reducing valve - Google Patents

Abstract

PURPOSE:To prevent a secondary pressure from abnormally rising even when a primary pressure is returned again by preventing an adjusting means from being over-displaced with a driving means even when the primary pressure is lowered. CONSTITUTION:When the secondary pressure is higher than a pressure to be set by a pressure setting spring 24, a diaphragm 28 is pushed up against the operating force of the pressure setting spring 24 and the aperture degree of a pilot valve 32 is made small. Accordingly, the aperture degree of a main valve body 46 is made small and the secondary pressure is made small and held to the setting pressure. On the other hand, when the secondary pressure is lower than the setting pressure, with the reverse operation of steam, the secondary pressure is made large and held to the setting pressure. When the primary pressure is lowered and a signal from a pressure sensor 66 in a primary side goes to be smaller than a setting pressure signal to be inputted from a setting part 61, the signals are compared in a microcomputer 60 and a signal for driving stop is sent to a motor 4. Then, the motor is stopped. Thus, an equipment can be prevented from being damaged by the abnormal rising of the secondary pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pressure reducing valve that adjusts a secondary pressure to a set pressure, and more particularly to a pressure reducing valve that automatically adjusts the set pressure.

2. Description of the Related Art A conventional automatic setting pressure reducing valve is shown in FIG. In the figure, reference numeral 24 denotes a pressure setting spring, and a spring receiver that contacts the diaphragm is attached to one end (not shown), and a spring receiver 22 is attached to the other end. This spring receiver 22 is in contact with the tip of the adjusting screw 10 via the ball 20. This adjustment screw 10
A male thread 16 is formed on the peripheral edge of the distal end thereof, and is screwed into a fixedly provided female thread part 18. A midway portion of the adjusting screw 10 is supported by a thrust bearing 15, and a hole is cut from the other end toward the inner depth. A retainer 12 and a pawl 14 are provided within this hole to form a spline hole. A spline shaft 8 is spline-fitted into this spline hole, and this spline I[lI8 is connected to the rotating shaft of the motor 4 via a speed reducer 6.

When the rotary shaft of the motor 4 is rotated in one direction, the spline shaft 8 rotates, and this rotation is transmitted to the adjustment screw 10 to rotate it. At this time, since the male threaded portion 16 of the adjusting screw 10 is screwed into the fixedly provided female screw 18, the adjusting screw 10 descends downward, the spring receiver 22 compresses the pressure setting spring 24, and the set pressure can be made larger. When the rotating shaft of the motor 4 is rotated in the opposite direction, the adjusting screw 10 is raised in the same manner as described above, and the pressure setting spring 24 is extended to reduce the set pressure.

There is a functional relationship between the value representing how far the tip of the adjusting screw 10 is from the reference position (screw position) and the degree of compression of the pressure setting spring 24, and thus the set pressure, which causes the motor 4 to rotate. By causing the adjustment screw 10 to take a predetermined screw position, a predetermined set pressure can be set.

In addition, as a method of controlling the adjusting screw 10 so that it takes a predetermined screw position, for example, a screw position detection device such as a potentiometer is provided, and the motor is rotated until the output from this generates a signal that detects the predetermined screw position. Is there a way to do it?
Alternatively, a method of controlling the number of pulses supplied to the stepping motor by using a stepping motor for which it is known how many times it will rotate when one pulse is supplied can be used.

As mentioned above, there must be a functional relationship between the screw position and the set pressure, so this relational expression is recorded in the microcomputer in the adjustment system, the set pressure is input to the microcomputer, and the screw position is determined. The microcomputer controls the motor 4 so that the adjusting screw 10 takes the calculated screw position.

Then, the actual secondary pressure is detected by a pressure sensor provided on the secondary side of the pressure reducing valve, and the screw position is adjusted so that the deviation between this secondary pressure and the set pressure becomes O.

Problems to be Solved by the Invention The pressure reducing valve itself has the function of maintaining the secondary pressure at a specified set pressure even if the secondary pressure changes due to load fluctuations or secondary pressure fluctuations. However, at this time, if the pressure reducing valve itself cannot adjust the secondary pressure in response to fluctuations in the primary pressure, a pressure sensor installed on the secondary side detects the secondary pressure, and the deviation between the secondary pressure and the set pressure is detected. Drive the motor so that becomes O.

However, if the primary pressure drops below the set pressure due to some reason, or if the boiler stops,
The motor attempts to return the secondary pressure to the set pressure and ends up compressing the pressure setting spring to its ultimate value.

When the secondary pressure rises again from this state, the pressure reducing valve is at the highest set pressure, so the secondary pressure may exceed the desired level, leading to equipment damage.

Therefore, the technical problem of the present invention is to provide an automatically setting pressure reducing valve which solves the above-mentioned problems.

``Means for Solving the Problems'' - The technical means of the present invention taken to solve the problems described above include a pressure reducing valve, a means for adjusting the set pressure of the pressure reducing valve, and a means for driving the adjusting means. means for detecting the secondary side pressure of the pressure reducing valve and generating a secondary side pressure signal representing the detected secondary pressure; and detecting the primary side pressure of the pressure reducing valve. A primary side pressure detection means that generates a primary side pressure signal representing the primary side pressure, and a setting section that generates a set pressure signal representing the set pressure, until the secondary side pressure signal becomes approximately equal to the above set pressure signal. The driving means includes control means for displacing the adjusting means, and means for generating a signal for stopping the driving means when the primary side pressure signal becomes smaller than the set pressure signal.

Upon application of the operating set pressure signal, the control means causes the drive means to displace the adjusting means to bring the secondary pressure to the set pressure. - When the secondary pressure changes due to a change in the secondary pressure, the driving means is driven so that the secondary pressure becomes equal to the set pressure. If the primary pressure further decreases and becomes lower than the set pressure, a signal is sent to the drive means to stop the drive means.

Effects As described above, according to the present invention, even if the primary pressure decreases, the driving means does not displace the adjusting means excessively, so even when the primary pressure returns again, the secondary pressure will not rise abnormally. do not have.

Example An example will be described showing a specific example of the above technical means.

(See FIG. 1) In this embodiment, parts corresponding to those in FIG. 2 are given the same reference numerals as in FIG. 2, and a detailed explanation of the drive section will be omitted.

A spring receiver 26 provided at the other end of the pressure setting spring 24
compresses the diaphragm 28 through the coil spring 3, lowers the pi
Push down against the force of step 4.

In this state, primary pressure fluid, for example -
When sub-pressure steam is introduced, a portion of this sub-pressure steam is
The screw 1-42 enters the lower chamber of the pilot valve 32 through the opened pilot valve 32 and the upper chamber of the piston 42 through the second passage 40. The main valve element 46 is opened by descending against the acting force of the main valve element 46. Most of the primary pressure steam introduced from the inlet 36 is sent out from the outlet 48 as secondary fumigation through the opened main valve body 46.

A portion of this secondary pressure steam is sent into the chamber below the diaphragm 28 via the third passage 50.

When the secondary pressure is higher than the pressure set by the pressure setting spring 24, the diaphragm 2B is pushed up against the acting force of the pressure setting spring 24, reducing the opening degree of the pilot valve 32, and therefore the main valve body 46 Reduce the opening degree of the secondary pressure and maintain it at the set pressure. On the other hand, if the secondary pressure is lower than the set pressure, the steam reverses its action to increase the secondary pressure and maintain it at the set pressure. In addition, 52 is a microcomputer 6Q that controls the main valve body motor 4 of the main valve body 46 and is attached to the pressure reducing valve. A pressure signal from a pressure sensor 62 representing the pressure is inputted.Furthermore, the functional relationship between the screw position of the adjustment screw 10 and the set pressure is stored in the microcomputer 60.

The setting pressure signal from the setting section 61 is sent to the microcomputer 60.
is given, the screw position is calculated according to the above functional relationship, and the motor 4 is controlled accordingly to set the pressure reducing valve to the set pressure.

When the secondary pressure changes due to load fluctuations or secondary pressure fluctuations, the motor 4 is operated until the deviation between the signal from the secondary side pressure sensor 62 and the set pressure falls within the standard deviation. drive and adjust the pressure setting spring 24.

When the primary pressure decreases and the signal from the pressure sensor 66 on the primary side becomes smaller than the set pressure signal input from the setting section 61, the microcomputer 60 compares the signals and sends a signal to the motor 4 to stop driving. The motor will stop.

In addition, by inputting the negative pressure signal to the microcomputer, if a pressure lower than the primary pressure is input when inputting the set pressure, an alarm will be issued and abnormalities can be detected in advance. can. In addition, the above-mentioned second pressure signal can be used in many other ways.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an automatic setting pressure reducing valve according to an embodiment of the present invention, and FIG. 2 is a sectional view of a drive unit of a conventional automatic setting pressure reducing valve. 4: Motor 10: Adjustment screw

Claims (1)

[Claims] 1. A pressure reducing valve, means for adjusting the set pressure of the pressure reducing valve, means for driving the adjusting means, and a secondary pressure signal that detects the downstream pressure of the pressure reducing valve and represents the detected secondary pressure. a secondary pressure detection means for detecting the primary pressure of the pressure reducing valve and generating a primary pressure signal representing the primary pressure, and a set pressure signal representing the set pressure. a setting unit that generates a setting unit; a control unit that causes the drive unit to displace the adjusting unit until the secondary pressure signal becomes approximately equal to the set pressure signal; and means for generating a signal for stopping said drive means when said pressure reducing valve is activated.