JPH0522081B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a pilot pressure reducing valve having a pilot valve equipped with a nozzle flapper mechanism.

BACKGROUND ART As shown in FIG. 3, a pilot type pressure reducing valve having a pilot valve equipped with a nozzle flapper mechanism is known as, for example, the 20 type ultra-precision relay manufactured by Fujikura Rubber Industries, Ltd.

In this valve, a signal pressure is applied to a port 52a or 52 in a measuring capsule (regulating pressure chamber) 51.
The flapper 52 of the pilot valve opens and closes the valve seat 53, and a small amount of air flows into the diaphragm chamber 54 and changes its pressure. At this time, the diaphragm chamber 54 is open to the atmosphere via the nozzle 64. When the pressure in the diaphragm chamber 54 increases, the pilot bellows 55 and the control bellows 56 move, the main valve body 57 opens, and the fluid flows from the primary chamber 58 to the secondary chamber 59.
The pressure in the secondary chamber 59 is introduced into a control chamber (feedback chamber) 62 via a flow path 61, and opens and closes the flapper 52 depending on the balance with the pressure in the measuring capsule (adjustment pressure chamber) 51. Pilot Velophram 55 and Control Velophram 5
6, the main valve body 57
The relief valve 60 operates appropriately in response to the opening/closing movement of the valve and discharges the fluid in the secondary chamber 59 from the discharge port 63.
Perform precise adjustment of secondary pressure.

In this type of pressure reducing valve, in order to improve sensitivity and responsiveness, the nozzle/flapper section of the pilot valve is made large, and the flow rate of the pilot valve section that drives the main valve body 57 is increased to increase the gain of the pilot valve section. It is necessary to increase it. However, looking at the characteristics of this type of pressure reducing valve in a high frequency range, it is found that the output flow of the pilot valve is accumulated in the diaphragm chamber that acts on the diaphragm connected to the main valve, or is discharged from the diaphragm chamber, thereby reducing the main valve body 57. The opening degree of the main valve changes, and the main valve responds in the form of a delay in filling and discharging the pilot valve output pressure due to the time integration of the pilot valve flow rate, etc. For example, if we consider an example in which the flapper opening of the pilot valve changes in a sinusoidal manner due to input, the flow rate of the pilot valve in the diaphragm chamber 54 also changes in a substantially sinusoidal manner. However, since the pilot valve flow rate is charged into and discharged from the diaphragm chamber 54, and the main valve body 57 is opened and closed according to the pressure change in that chamber, the pressure change to the main valve body 57 is equal to the integral value of the pilot valve flow rate. handle. Therefore, the change in the opening degree of the main valve body 57 is simply as follows:
It changes in the form of a cosine wave, which is an integral value for a sine wave. In other words, the phase of the opening of the main valve body is at most 90 degrees relative to the phase of the flapper opening of the pilot valve.
There will be a degree of delay. Similarly, the pressure change in the secondary side chamber 59 of the main valve, that is, the pressure change in the feedback chamber 62, with respect to the opening degree of the main valve body 57
The pressure response of the secondary chamber 59 of the main valve is delayed by a maximum of 90 degrees with respect to the phase of the opening of the main valve body. Based on the change in the flapper opening degree of the pilot valve, a change in the pressure response of the secondary side chamber 59 of the main valve, that is, a feedback pressure change, occurs through a change in the opening degree of the main valve, but this change ultimately causes the opening of the main valve body 57 to change. This is the sum of the phase delay of degrees and the phase delay of the pressure change in the secondary side chamber 59.

For this reason, the phase of the pressure in the secondary side chamber, that is, the phase of the feedback pressure, is delayed by 180 degrees at most with respect to the opening degree phase of the flapper. If delay elements such as friction are added to this, the phase delay of the feedback pressure becomes closer to 180°, and the phase of the feedback pressure becomes in phase with the input, so the system becomes a divergent body.

A pilot type pressure reducing valve with characteristics in the high frequency range as described above becomes stable when the gain of the pilot valve section is small because the amplitude becomes sufficiently small until the response delay reaches 180 degrees, but when the gain is If it increases, there is a problem in that a hunting state occurs in which disturbance or the like becomes a driving force and continues self-transmission.

In the conventional pressure reducing valve described above, it is unavoidable that the feedback pressure has a phase delay of up to 180° with respect to the displacement of the flapper. Therefore, it is impossible to avoid the risk of a hunting situation occurring.

Purpose The present invention aims to solve the above-mentioned conventional problems and provide a pilot type pressure reducing valve that does not cause oscillation.

Configuration The present invention achieves the above-mentioned objects by providing an input port, a primary chamber leading to the input port, an outlet port, a secondary chamber leading to the outlet port, and a space between the primary chamber and the secondary chamber. a main valve body having a main valve seat formed in the main valve seat and a pilot pressure chamber, a main valve body that can be seated on the main valve seat, and a main valve body that is connected to the main valve body by a valve stem and that is connected to the secondary side chamber and the pilot a drive member that is hermetically and movably disposed so as to form a boundary with the pressure chamber; a pilot valve portion that opens into the pilot pressure chamber; and a feedback portion that connects the secondary side pressure chamber to the pilot valve portion. A pilot pressure reducing valve comprising a nozzle/flapper mechanism having a nozzle and a flapper provided in a pilot flow passage in which the pilot valve part is connected to the pilot pressure chamber, wherein the pilot valve part an adjustment drive member connected to the pilot valve body formed as the flapper, a feedback chamber connected to the feedback passage with the adjustment drive member in between, and an adjustment provided on the opposite side of the feedback chamber. a pressure chamber; and a regulating fluid inlet port that opens into the regulating pressure chamber via a restriction;
The time constant T _c =CV/S (C is a constant) determined by the volume of the adjustment pressure chamber and the area S of the aperture is larger than the predetermined feedback pressure fluctuation period T _f of the feedback chamber. The volume V of the regulating pressure chamber is adjusted so that the volume V is as small as possible.
This was achieved by a pilot type pressure reducing valve characterized in that the area S of the orifice is set.

Effect According to the present invention, the volume of the regulating pressure chamber and the area of the restriction provided between the regulating pressure chamber and the regulating fluid inlet port are set so that the time constant of the regulating pressure chamber is larger than the hunting period due to feedback. Therefore, even if there is a fluctuation in the pressure acting on the pilot valve body, the effect on the flow rate flowing in and out through the throttle is small. By making the volume of the regulating pressure chamber as small as possible, the influence of fluctuations in feedback pressure on the flapper displacement can be reduced due to the spring action of the regulating fluid. Therefore, even if a phase difference of about 180 degrees occurs in the feedback pressure fluctuations with respect to the fluctuations in the pilot valve body, it has become possible to avoid transition to the hunting state.

Embodiments The details of the structure and operation of the present invention will be explained based on embodiments shown in the drawings.

In Fig. 1, the main valve body 1 has an inlet port 2.
, a primary side chamber 3 communicating with the inlet port 2, an outlet port 4, a secondary side chamber 5 communicating with the first port 4,
A valve seat 6 formed between the primary chamber 3 and the secondary chamber 5 and a pilot pressure chamber 7 are provided.

A main valve body 8 can be seated on the valve seat 6, and a driving member 10 is connected to the main valve body 8 by a valve rod 9.

The drive element 10 is, for example, designed as a diaphragm, as shown in FIG. 1, in which case the pilot pressure chamber 7 forms a diaphragm chamber. In another example, the drive member 10 can be designed as a piston, in which case the pilot pressure chamber 7 is designed as a piston chamber.

A port 12 of a pilot valve 11 opens into the pilot pressure chamber 7. The pilot valve 11 has a pilot valve body 14 that can be seated on a pilot valve seat 13 provided in the port 12. Pilot valve body 1
4 is connected by a valve stem 15 to an adjusting drive member 16 . The adjusting drive element 6 can also be designed as a piston, which in FIG. 1 is designed as a diaphragm.

The super drive member 16 is arranged so as to border a feedback chamber 18 and a regulating pressure chamber 19, and the feedback chamber 18 is
It is connected to the next side chamber 5.

A regulating fluid input port 21 opens into the regulating pressure chamber 19 via a throttle 20 .

The pilot valve 11 has a nozzle flapper mechanism, and the nozzle flapper mechanism has a flapper formed as a pilot valve body 14 for opening and closing the port 12, and a fixed nozzle 22, which is connected to the pilot pressure chamber 7. The pilot flow path has a pilot inflow path 23 and a pilot outflow path 24 connected to the pilot flow path. In the example of FIG. 1, the fixed nozzle 22 is provided in the pilot outlet passage 24. In the example shown in FIG. In the example shown in FIG. 1, the pilot inlet passage 23 is connected to the port 12, and the pilot outlet passage 24 is connected to the pilot pressure chamber 7 via the nozzle 22.

The operation will be explained below.

When the pressure _P1 in the secondary chamber 5 drops below a predetermined value,
The pressure P ₃ in the feedback chamber 18 decreases, and the adjustment drive member 16 is moved by the pressure P ₄ in the adjustment pressure chamber 19, causing the pilot valve body 14 to move toward the pilot valve seat 1.
Separated from 3.

A chamber 25 connected to the port 12 stores pilot fluid supplied through the pilot inflow passage 23, and the pilot fluid flows into the pilot pressure chamber according to the opening degree of the pilot valve seat 13, that is, the opening degree of the flapper (pilot valve body) 14. 7.

Pilot fluid is temporarily stored in the pilot pressure chamber 7 due to resistance from the nozzle 22, and the driving member 1
0 is the pressure in the pilot pressure chamber 7 and the pressure in the secondary side chamber 5
It is moved according to the differential pressure with P ₁ to move the main valve 8 and open the main valve seat 6. This causes the air to flow in and increase the pressure _P1 in the secondary chamber 5.

The pressure increase in the secondary chamber 5 is caused by the feedback flow path 1.
7 to the feedback chamber 18 and acts on the adjustment drive member 16.

When the pressure in the secondary chamber 5 rises to a predetermined level, the adjustment drive member 16 is moved in accordance with the balance with the pressure in the adjustment pressure chamber 19, and the pilot valve body 14, ie, the flapper, is moved to close the port 12.

The supply of pilot fluid to the pilot pressure chamber 7 is stopped by closing the port 12, but the flow continues from the pilot outlet passage 24 through the nozzle 22, so the pressure _P2 gradually decreases, and the pressure P2 between the pilot fluid 7 and the secondary chamber 5 is reduced. The drive member 10 is moved according to the pressure balance, and the main valve body 8 is moved accordingly, and the main valve seat 6 is closed.

Due to pressure fluctuations in the secondary chamber 5, pressure fluctuations also occur in the feedback chamber 18, and, for example, a pressure wave with a period T _f is formed. The adjustment drive member 16 is affected by this pressure wave, causing the main valve body to oscillate. Therefore, it is necessary to eliminate pressure fluctuations in the feedback chamber.

When the volume of the regulating pressure chamber 19 is V, and the area of the throttle 20 between the regulating fluid inlet port and the regulating pressure chamber 19 is S, the time constant of the regulating pressure chamber 19 is CV/S>T _f =CV/
It becomes S. Here C is a constant.

When the time constant T _c of the regulating pressure chamber 19 is set to be larger than the period T _f of feedback pressure fluctuation,
As regulating fluid, for example air, enters and exits through the restrictor 20, the flow rate through the restrictor 20 decreases in response to pressure waves or pressure fluctuations.

The regulating fluid flowing into the regulating pressure chamber 19 can be considered to have a kind of spring action, the spring constant K being expressed as K=PA ² /V. Here, A is the effective area of the adjusting drive member 16.

By reducing the volume V of the regulating pressure chamber 19, the spring constant can be increased.

The larger the spring constant, the less the adjustment drive member 16 will fluctuate in response to fluctuations in the feedback pressure _P3 . This reduces the fluctuation of the pilot valve pair 14, ie the flapper, as indicated by the arrow x.
In this way, fluctuations in the feedback pressure _P3 can also be reduced.

Therefore, the volume V of the regulating pressure chamber 19 is determined by the time constant T _c of the regulating pressure chamber 19, which is determined in relation to the throttle area S.
It is possible to focus and stop the vibration by setting so that the period of the feedback pressure fluctuation is equal to or longer than the hunting period T _f and the volume V is set to be as small as possible.

The nozzle flapper mechanism can also be modified from the example shown in FIG. 1 as shown in FIG. 2. That is, the port 12 and the pilot outlet passage 24 are connected, and the pilot valve seat 1 is connected to the pilot outlet passage side of the port 12.
3 is formed, a pilot valve body 14 as a flapper is seated on the pilot valve seat 13 on the side of the pilot outflow passage, and a nozzle 22 is formed between the pilot pressure chamber 7 and the pilot inflow passage 23. In the example shown in FIG. 1, the pilot valve seat 13 is opened when the pilot valve body 14 moves downward in the drawing due to the action of the adjusting drive member 13, and closes when it moves upward, whereas in the example shown in FIG. The difference is that the pilot valve seat 13 closes when the pilot valve body 14 descends and opens when it rises. However, since the action of the pilot fluid on the drive member 10 is substantially the same, the same or corresponding members as in FIG. 1 will be given the same reference numerals and detailed explanations will be omitted.

Effects According to the present invention, hunting of the main valve body can be prevented by a simple structure and means of selecting the size of the regulating pressure chamber and the area of the restriction of the regulating fluid inlet port. In particular, by considering only the hunting frequency range and lowering the gain of the pilot section for that frequency, valve oscillation could be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a pilot type pressure reducing valve according to the present invention, FIG. 2 is a sectional view of another embodiment, and FIG. 3 is a sectional view of a conventional pressure reducing valve. 1...Main valve body, 2...Inlet port, 3...1
Next side chamber, 4...Exit port, 5...Secondary side chamber, 6
... Main valve seat, 7 ... Pilot pressure chamber, 8 ... Main valve body, 9 ... Valve stem, 10 ... Drive member, 11 ... Pilot valve, 12 ... Port, 13 ... Pilot valve seat, 14...Pilot valve body (flapper),
16...Adjustment drive member, 17...Feedback channel, 18...Feedback chamber, 19...Adjustment pressure chamber, 20...Aperture, 21...Adjustment fluid inlet port, 22...Nozzle, 23...Pilot inflow Road, 24...Pilot outlet road.

Claims (1)

[Claims] 1. An inlet port 2, and 1 leading to the inlet port 2.
A downstream chamber 3, an outlet port 4, a secondary chamber 5 communicating with the outlet port 4, a main valve seat 6 formed between the primary chamber 3 and the secondary chamber 5, and a pilot pressure chamber 7. a main valve body 1 having a main valve body 1, a main valve body 8 which can be seated on the main valve seat 6, and a valve body 8 connected to the main valve body 8 by a valve rod 9 between the secondary side chamber 5 and the pilot pressure chamber 7. A drive member 10 that is arranged in a sealed and movable manner so as to form a boundary, a pilot valve section 11 that opens into the pilot pressure chamber 7, and a feedback flow that connects the secondary side pressure chamber 5 to the pilot valve section 11. passage 17, and the pilot valve portion 1
1 is a pilot type pressure reducing valve equipped with a nozzle flapper mechanism having a nozzle 22 and a flapper 14 provided in pilot flow passages 23 and 24 connected to the pilot pressure chamber 7, wherein the pilot valve portion 11 is connected to the flapper 14. 14
an adjustment drive member 16 connected to a pilot valve body formed as a pilot valve; a feedback chamber 18 connected to the feedback passage 17 with the adjustment drive member 16 in between; and a regulating fluid inlet port 21 that opens into the regulating pressure chamber 19 via a throttle 20, and has a volume V of the regulating pressure chamber 19.
and the area S of the aperture 20.
The volume V of the adjustment pressure chamber 19 and the aperture 20 are adjusted such that T _c =CV/S is larger than the predetermined feedback pressure fluctuation cycle T _f of the feedback chamber 18, but the volume V is as small as possible. A pilot type pressure reducing valve characterized in that an area S is set.