JPS6224143Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to an improved relief valve.

[Conventional technology]

In a conventional relief valve, as illustrated in FIG. has been established. The valve chamber 5 formed in the cylindrical support part 2 is communicated with the main flow passage 6 through the valve hole 4, and is bypassed through a substantially rectangular window 7 formed in the peripheral wall of the cylindrical support part 2. It communicates with the flow path 8. A support member 9 is provided at the other end of the cylindrical support portion 2.
is slidably inserted therein, and the valve body 1 is provided with a guide member 10 concentric with the support member 9. The valve stem 11 has one end connected to the support member 9, and the other end slidably fitted into the guide member 10. A valve body 12 is supported at an intermediate portion of the valve stem 11, facing the valve seat 3 and loosely inserted into the valve stem 5.
The valve stem 11 is connected to the diaphragm 13 via the support member 9.
and is elastically pressed in the closing direction by a compression coil spring 14.

When the pressure of the fluid flowing into the main flow path 6 is guided to the control pressure chamber 15 through the control flow path 16, the axial position of the valve body 12 is controlled according to the pressure, thereby opening the valve hole 4. As the temperature changes, the amount of fluid released from the main flow path 6 through the valve port 4, the valve chamber 5, and the window 7 to the bypass flow path 8 changes, and the fluid pressure in the main flow path 6 is thus maintained almost constant. It is said that it will be done.

[Problem that the invention attempts to solve]

However, in the above conventional example, the flow rate Q
- When used in conjunction with a centrifugal pump whose pressure H characteristics are as shown by the broken line A in Figure 4, the overall characteristics will be as shown by the dashed line B in the figure, and as the flow rate Q increases, the pressure H will increase. Because of this, good constant pressure characteristics cannot be obtained. Furthermore, when used in conjunction with a pump in which the ratio of pressure change to flow rate change is relatively small, the Q-H characteristic may actually deteriorate.

To explain the reason _in detail, considering the pressure _balance at a certain _time during _{operation in} FIG _. ) However, f ₁ : Force of compression coil spring 14 pushing diaphragm 13 P ₀ S ₁ : Atmospheric pressure P ₀ is diaphragm 1 with pressure receiving area S ₁
Force pushing 3 P ₂ (S ₂ - S ₃ ): Secondary pressure P ₂ is the effective pressure receiving area (S ₂
−S ₃ ) force pushing the valve body 12, S ₂ ... cross-sectional area of the valve body,
S ₃ ... Valve stem cross-sectional area Next, the force Fb in the direction of opening the valve body 12 is Fb = P ₁ (S ₁ - S ₄ ) + P ₁ S ₂ = P ₁ (S ₁ + P ₂ - S ₄ ) However, P ₁ (S ₁ - _{S 4} ): Primary pressure P ₁ in the control pressure chamber 15 is the diaphragm 1 with an effective pressure receiving area (S ₁ - _{S 4} )
P ₁ S ₂ : Force of primary pressure P ₁ pushing valve body 12 At a certain time, valve body 12 moved in the opening (closing) direction from the case of Fa=Fb, and the primary pressure P ₁ was maintained. Assuming that, Fa′=f ₁ ′+P ₀ S ₁ +P ₂ ′(S ₂ −S ₃ ) P ₂ ′≒P ₂ , so =f ₁ ′+P ₀ S ₁ +P ₂ (S ₂ −S ₃ )= Fa−(f ₁ ′−f ₁ )=Fa From the assumption that the primary pressure P ₁ is maintained, Fb′=Fb
Also, from the force balance relationship, Fa′=Fb′ and Fa′=
Fb=Fa, which causes a contradiction in the assumption.

In other words, the primary pressure changes to compensate for the force (f ₁ '-f) based on the displacement of the compression coil spring 14 to maintain balance, and logically the flow rate (Q)
A change in pressure (H) accompanying a change in is unavoidable.

Therefore, in the past, it was thought that the purpose of this function was to prevent excessive pressure from being activated when the pressure exceeded a set level, rather than to obtain constant pressure characteristics.

The present invention has been developed in view of the above circumstances, and its purpose is to provide a relief valve that can maintain a substantially constant pressure regardless of fluctuations in flow rate.

[Means for solving problems]

In the present invention, the outer peripheral part of the valve body is formed so as to be in sliding contact with the inner peripheral wall of the valve chamber, and the window that communicates the valve chamber and the bypass flow path has a circumferential width in the part near the end on the valve hole side. It is characterized by being formed so that it becomes narrower as the width increases.

[Effect]

In the conventional case, the relief flow rate is adjusted by the opening formed between the valve body and the valve seat.For example, if the displacement of the valve body is doubled (1/2 times), the opening is The change in area of is also doubled (1/2 times), resulting in the characteristic shown by B in FIG.

On the other hand, according to the structure of the present invention, the opening area of the window formed in the cylindrical support part can be set to change in area as appropriate with respect to the displacement of the valve body. For example, if the opening shape is made triangular, The displacement is doubled (1/
2 times), the area change of the opening is 4 times (1/4 times)
Therefore, the relief flow rate can be increased (decreased) compared to the conventional method.

Compared to the conventional example described above, the rate at which the pressure decreases (increases) as the flow rate increases (decrease) is small, and better constant pressure characteristics can be obtained.

〔Example〕

Hereinafter, the present invention will be described with reference to an illustrated embodiment. In FIGS. 2 and 3, the valve body 20 includes a cylindrical support portion 21. As shown in FIGS. This cylindrical support part 21
A valve hole 23 is formed in a valve seat 22 provided at one end of the valve seat 22 . The valve chamber 24 formed in the cylindrical support part 21 is communicated with the main flow path 25 through the valve hole 23 and communicated with the bypass flow path 27 through the window 26 formed in the peripheral wall of the cylindrical support part 2 . It is communicated. A support member 28 is slidably fitted to the other end of the cylindrical support portion 21 . The valve stem 29 has one end connected to the support member 28 and the other end connected to the valve seat 22.
A valve body 30 inserted into the valve chamber 24 is supported opposite to the valve body 30 . The valve stem 29 is connected to the diaphragm 31 via the support member 28 and is biased in the closing direction by a compression coil spring 32. Bento box 2
0 is provided with a control pressure chamber 33 located on the opposite side of the compression coil spring 32 with respect to the diaphragm 31. The above general configuration may be the same as in the conventional example.

The valve body 30 is formed such that its outer peripheral portion is slidably inscribed in the peripheral wall 34 of the cylindrical support portion 2 . Further, the window 26 is formed such that the width W in the circumferential direction becomes smaller as the portion closer to the valve seat 22 approaches (see FIG. 3). The rate of change of this width W in the axial direction is determined by the diaphragm 31 and the compression coil spring 32.
It is set as appropriate depending on the characteristics of etc.

In the relief valve configured as described above, the pressure of the fluid flowing into the main flow path 25 is controlled by the control flow path 35.
When the pressure is guided to the control pressure chamber 33 through the diaphragm 31, this pressure exerts an urging force on the valve stem 29, a force pushing the valve body 30 from the main channel 25 side, and a restoring force of the compression coil spring 32. The valve body 30 is moved to a position where these are in equilibrium. As a result, the valve chamber 24 is communicated with the main flow path 25 through the valve hole 23 and with the bypass flow path 27 through the window 26, so that a part of the fluid flowing through the main flow path 25 is communicated with the bypass flow path 27. As a result, the pressure of the fluid in the main flow path 25 is controlled.

According to the above configuration, the outer peripheral portion of the valve body 30 is connected to the valve chamber 2.
4, and the window 26 is formed so that the width W becomes narrower in the circumferential direction closer to the valve seat 22, and the relief flow rate can be adjusted by the opening formed with the valve body 30. Therefore, the rate of change in the opening area of the window 26 with respect to the displacement of the valve body 30 is greater than that of the conventional product. Therefore, when the flow rate in the main channel 25 increases (decreases) and the pressure begins to decrease (increase), the relief flow rate is smaller (more) than in the conventional example, and the pressure drop (rise) is reduced. ,
As shown by solid line C in FIG. 4, the pressure can be maintained substantially constant.

In addition, since the valve body 30 is in sliding contact with the peripheral wall 34 of the cylindrical support part 21, the valve body 30 and the cylindrical support part 2
Not only is it possible to control the flow rate by controlling the opening area of the window 26 without allowing the fluid to flow through the gap between the peripheral walls 34 of 1, but it is also possible to extend the valve stem 11 across the main flow path 6 as in the conventional example, Guide member 1 in box 1
Since there is no need to provide a zero, the structure is simpler and easier to manufacture, and there are also effects such as a reduction in fluid flow resistance in the main channel.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications and applications can be made within the scope of the gist thereof.

[Effect of idea]

As explained above, according to the present invention, the pressure can be kept substantially constant regardless of fluctuations in the flow rate, and the constant pressure characteristics are improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional example, Fig. 2 is a sectional view showing an embodiment of the present invention, Fig. 3 is a side view showing the main parts of the same example, and Fig. 4 shows flow rate-pressure characteristics. It is a line diagram shown for comparison. 20... Valve box, 22... Valve seat, 23... Valve hole,
24...Valve chamber, 25...Main flow path, 26...Window, 2
7... Bypass flow path, 30... Valve body, 31... Diaphragm, 32... Compression coil spring, 33...
Control pressure chamber, 34...peripheral wall.

Claims (1)

[Scope of utility model registration request] It communicates with the main flow path through a valve hole opened at the end of the cylindrical support provided in the valve box, and also communicates with the bypass flow path through a window opened in the peripheral wall of the cylindrical support. and a valve body that is inserted into the valve chamber to open and close the valve hole, and the valve body is actuated according to the pressure in the main flow path to control the opening and closing of the valve hole. In the relief valve that adjusts the relief flow rate from the main flow path to the bypass flow path via the valve chamber, the outer periphery of the valve body is slidably inserted into the inner peripheral surface of the cylindrical support part, and the The opening width in the circumferential direction is narrower at the end closer to the valve hole side,
A relief valve characterized in that the amount of opening of the window is controlled by the amount of axial movement of the valve body.