JPH0314104B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a pressure control valve, and more specifically, the pressure on the outlet side (secondary side) is not affected by fluctuations in the pressure on the inlet side (primary side). This invention relates to a pressure control valve that can always obtain stable secondary pressure.

Conventionally, this type of pressure control valve has a structure shown in FIG. That is, it includes a casing 4 having a fluid inlet 1, a fluid outlet 2, and a valve opening 3 provided between the inlet and the outlet. A valve 5 is provided in the casing 4 to open and close the valve opening,
A diaphragm 6 is also provided to control this valve. The valve 5 is biased to close the valve opening 3 by a spring 5α. This diaphragm has a structure in which it is displaced in response to pressure on the secondary side and closes the valve 5 due to an increase in the pressure. A control passage 7 is provided in the casing 4 separately from the passage communicating between the inlet 1 and the outlet 2, and this control passage also extends so as to communicate the inlet 1 and the outlet 2.

This control passage is provided with a throttle part 8 and a relief valve 9, and the set pressure of the relief valve 9 directly acts on the diaphragm 6, so that an increase in the set pressure closes the valve 5. In a steady state, the secondary Balances the pressure. When the secondary pressure changes due to fluctuations in the primary pressure or secondary load, the diaphragm 6 displaces accordingly and opens and closes the valve 5, thereby establishing the relationship between secondary pressure = relief valve set pressure. is controlled by. In the structure shown in FIG. 1, a pressure balance mechanism is provided to introduce secondary pressure before and after the valve 5, and the influence of the primary pressure and the secondary pressure applied before and after the valve 5 is removed. As described above, conventional pressure control valves have had the disadvantage that the larger the valve opening, the more a pressure balance mechanism as described above is required and the structure becomes more complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure control valve that eliminates such conventional drawbacks and has a simplified valve structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 2, 3, and 4. Figure 2 is the first
This is an embodiment corresponding to the figure, and FIG. 3 is an embodiment in which a diaphragm is arranged on the primary side of the valve. Furthermore, the second
3 and 3, substantially the same parts as in FIG. 1 are given the same reference numerals.

It should be noted that in the present invention, the control passage 7 is provided with two spaced apart throttle parts, a first throttle part 10 and a second throttle part 11. These aperture parts 10,
11, a passage 12 is provided in the casing, which passage communicates with a chamber in which a diaphragm 6 is provided. FIG. 4 shows a state in which fluid is flowing in the pressure control valve of the present invention. In this state, the valve 5 is open, indicating that fluid is flowing from the inlet 1 toward the outlet 2. In this case, the diaphragm 6 remains stationary in a balanced position. In other words, the valve 5 remains in the open position depending on the flow rate.

Now, in the case of the embodiment shown in FIG. 2, the operation is as follows. Here, the area of valve opening 3 is
S ₁ , diaphragm effective area S ₂ , first constriction section 10
The flow resistance of the second throttle part is C ₁ , the flow resistance of the second throttle part is C ₂ ,
Let the load of the spring 5α be f. Also, the primary pressure
P ₁ , outlet pressure P ₂ , diaphragm control pressure P ₃
shall be.

When the set pressure of the relief valve is P ₀ and the diaphragm is stationary at a balanced open position as shown in FIG. 4, the following balance equation holds true.

S ₁ ·P ₁ +S ₂ ·P ₂ +f=S ₁ ·P ₂ +S ₂ ·P ₃ ...(1) Also, the relational expression of the flow rate before and after the throttle is as follows.

C ₁ √ ₁ − ₃ = C ₂ √ ₃ − ₀ ...(2) Equations (1) and (2) hold because the diaphragm is balanced and stationary as described above. There is no change in the volume of the back pressure chamber, so the flow rate through the first constriction section 10 and the second constriction section 1
This is because the flow rate passing through 1 is equal. Here, if (C ₁ /C ₂ ) ² = α, the secondary pressure P ₂ is (1), (2)
From the formula, P ₂ = 1/S ₂ −S ₁ {(α/1+αS ₂ −S ₁ )P ₁ +1/1+αS ₂・P ₀ −f} ...(3) Therefore, the coefficient of P ₁ , that is (α /1+αS ₂ −S ₁ ) is set to 0, α/1+αS ₂ =S ₁ , that is, α=S ₂ −S ₁ /S ₁ ...(4) By setting, the secondary pressure P ₂ becomes P ₂ =P ₀ −1/S ₂ −S ₁ f ...(5), P ₂ is determined by the setting of P ₀ and the primary pressure
It is not subject to fluctuations in P ₁ .

In the embodiment shown in FIG. 3, the process is as follows.

The balance relational expression for the diaphragm is S ₂ · P ₁ + S ₁ · P ₂ + f = S ₂ · P ₃ + S ₁ P ₁ ...(6) The relational expression for the flow path before and after the throttle part is the same as above.
From equations (2) and (6), P ₂ = 1/S ₁ {−(1/1+αS ₂ −S ₁ )P ₁ +1/1+αS ₂・P ₀ −f ……(7) Same as above, the coefficient of P ₁ is In order to make it zero, 1/1 + αS ₂ = S ₁ , that is, α = S ₁ /S ₂ −S ₁ ...(8), so P ₂ = P ₀ + 1/S ₁ f ...(9), and P ₂ is determined by the setting of P ₀ and is the primary pressure
It is not subject to fluctuations in P ₁ .

According to the present invention, there is the practical benefit of simplifying the valve portion by simply providing one more restrictor in the control passage, eliminating the need to provide a pressure balance mechanism in the valve itself as in the prior art.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional pressure control valve, Figs. 2 and 3 are sectional views showing an embodiment of the pressure control valve according to the present invention, and Fig. 4 is a sectional view of the pressure control valve in an open state. FIG. 4 is a cross-sectional view similar to FIGS. 1...Inlet, 2...Outlet, 3...Valve opening, 4...
...Casing, 5...Valve, 6...Diaphragm,
7... Control passage, 9... Relief valve, 10, 11
...Aperture section.

Claims (1)

[Scope of Claims] 1. A casing having a fluid inlet, a fluid outlet communicating with the inlet, and a valve opening provided in a passage between the inlet and the outlet, and a valve that opens and closes the valve opening; A pressure control valve comprising a diaphragm that is displaced in response to inlet side pressure or outlet side pressure and is disposed in a direction to close the valve when the inlet side pressure or outlet side pressure increases, the passage between the inlet and the outlet; Separately, a control passage leading from the inlet to the outlet is provided in the casing, and the control passage is provided with a first constriction part, a second constriction part, and a relief valve in order from the inlet side, and the first constriction part and the second constriction part are provided in the control passage in order from the inlet side. pressure is applied to the side of the diaphragm opposite to the side to which the inlet or outlet pressure is applied, and the increase in pressure causes the valve to open, and the flow resistance C ₁ of the first constriction part to be increased.
The flow resistance C ₂ of the second throttle part, the area S ₁ of the valve opening, and the effective area S ₂ of the diaphragm are such that the value of (C ₁ /C ₂ ) ² is S ₂ −S ₁ /S ₁ or S ₁ /S ₂ - A pressure control valve, characterized in that it is set equal to the value of S ₁ .