JPS6143009Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Industrial application field) This invention is used in large-capacity gas containers such as blast furnaces and ore sintering furnace equipment, and when the inside of the flow path reaches a predetermined set pressure or higher, the This invention relates to a safety valve that is opened and maintained in its open state.

(Prior art and problems) In general, as safety valves for large-capacity gas containers such as blast furnaces and ore sintering furnace equipment, the weight type shown in Figure 1a, the spring type shown in Figure 1b, etc. have been conventionally used. There is. These pressures are higher than the set pressure, that is, the force in the opening direction that acts on the valve bodies 102, 202 based on the pipe pressure is the moment of the weight 108, the weight of the valve bodies 102, 202, the elastic force of the spring 208, etc. When the force in the closing direction is overcome, the tube opens as shown in FIGS. 1a and 1b, releasing the high-pressure fluid inside to the outside and preventing the pressure inside the tube from increasing beyond the set pressure.

However, even if such a conventional safety valve operates at a pressure above a predetermined pressure, the degree of opening will depend on the degree of internal pressure, and once the internal pressure returns to below the predetermined pressure, the valve will be fully closed again. This allows the pressure inside the pipe to rise up to the set pressure.
Once the pressure reaches a predetermined level or higher, it is necessary to release the pressure rapidly, and it is not suitable for high-pressure vessel equipment where the open state needs to be maintained until the abnormality is repaired.

In addition, in the conventional safety valve shown in Fig. 1, the larger the diameter, the heavier the valve body, and the one in Fig. 1a requires a large weight, resulting in a significant increase in total weight. In particular, it is difficult to install the valve in a high place, and furthermore, in the case of the valve shown in FIG. 1b, if the diameter is large, the weight increases and there are problems such as the valve not functioning as a safety valve.

On the other hand, as a safety valve that maintains its state once it is opened, for example,
Using a spring and cam like No. 32493,
A structure is known in which, when the valve body is opened beyond a certain level, the valve body is biased in the opening direction by the elasticity of a spring via a cam.

However, although a safety valve with this structure is suitable for opening and closing a small-diameter exhaust hole with a lightweight valve body, it is suitable for opening and closing a small-diameter exhaust hole with a lightweight valve body, but it is suitable for opening and closing a small-diameter exhaust hole with a lightweight valve body. To adapt to piping equipment, it is necessary to release a large amount of gas in a short time, so the safety valve itself is large and heavy, and as in Utility Model Publication No. 35-32493, the weight of the valve body is A structure that supports the opening and maintains the open state requires a powerful spring, making it difficult to manufacture and, in some cases, requiring a great deal of effort to assemble, resulting in problems such as being inappropriate.

In view of these conventional problems, the present invention is suitable for large-diameter safety valves that can be used in large-capacity, high-pressure gas containers such as blast furnaces and ore sintering furnace equipment, and can rapidly release pressure. Once activated, it can continue to remain fully open,
Furthermore, it is an object of the present invention to provide a safety valve with a simple structure that can be made lightweight as a whole even when the diameter is increased, and can be operated with a small acting force.

(Means for Solving the Problems) In order to solve these conventional problems, the present invention includes a valve box that forms part of the flow path, and a valve shaft that is rotatably supported within the valve box. , a butterfly valve body that opens and closes the flow path, and a valve seat that is fixed to the inner surface of the valve box and abuts an edge of one side of the butterfly valve body in a valve-closing manner, and the valve shaft is connected to the butterfly valve body. A lever member is attached to the valve shaft eccentrically to one side from the center, and a lever member is attached to the valve shaft outside the valve box.
A weight is supported by the lever member and is slidable downward under its own weight along the inclination of the lever member, and when the butterfly valve body is in a closed state, the weight pushes the lever member in the valve closing direction. The lever member is installed so as to be slightly inclined from the horizontal so that the lever member is located on the side where the pressure is applied, and the butterfly valve body is moved in the opening direction by the pressure in the flow path, and the inclination direction of the lever member is changed. Thus, a safety valve is constructed in which the weight slides toward the side that urges the butterfly valve element in the opening direction, and the open state is maintained by the weight of the weight.

(Function) Normally, this safety valve is energized by the weight of the weight in the direction in which the butterfly valve element comes into contact with the valve seat, thereby closing the flow path.
When the internal pressure of the flow path on the valve seat side increases, the valve stem is in an eccentric position, so the internal pressure of the flow path adds a moment in the direction that opposes the force exerted by the weight of the butterfly valve body, and that moment is caused by the weight. When the force becomes larger than the applied force, the butterfly valve body rotates and the flow path is opened. This rotational action changes the inclination direction of the lever member supporting the weight, which changes the inclination direction of the lever member supporting the weight, and the weight moves toward the opposite end of the lever member along the inclination. Move to. As a result, the weight of the weight acts on the butterfly valve element in the opening direction, and even if the inside of the flow path is depressurized by the outflow of gas, the open state of the butterfly valve element is maintained.

(Example) Next, an example of the implementation of the present invention will be explained with reference to the drawings from FIG. 2 onwards.

FIG. 2 is a front view of the safety valve according to the present invention, and FIG. 3 is a partially cutaway side view of the same.

In the figure, 1 is a valve box formed into a rectangular cylindrical shape from a steel plate or the like, and piping bolt holes 1c are bored at appropriate pitches on the entire circumference of the flange portions 1a and 1b forming the front and rear end surfaces in the axial direction of the valve box 1. It is set up.

A rectangular flat plate-shaped valve body 2 is integrally fixed to a horizontally suspended valve shaft 3 eccentrically upward from a horizontal center position with a slight gap between it and the inner edge of the valve body 1. ing. The valve shaft 3 is rotatably supported by bearing units 4, 4 fixed to both side walls of the valve body 1, and the valve body 2 is also rotatably supported integrally with the valve shaft 3. A plurality of reinforcing ribs 5 are fixed to the front and rear surfaces of the valve body 2 at appropriate pitches, and a valve seat member is provided on the inner bottom surface of the lower part of the valve body 1 so as to be in contact with the lower part of the valve body 2 in the fully closed state shown in the figure. 6 is fixed.

A bracket member 7 is attached to one of the shaft ends (right side in FIG. 2) of the valve shaft 3 that protrudes from the valve body 1.
This bracket member 7 is keyed to rotate together with the valve body, and this bracket member 7 is set vertically upward when the valve body 2 is fully closed, as shown in FIG. A fixed weight 8 is fixed to the upper end of 7.

The center portion of a lever member 9 formed by cutting an I-shaped steel or the like to an appropriate length is fixed to the lower end of the bracket member 7, and a movable weight 10 is inserted into a groove 9a of the lever member 9 via rollers 11. It is slidably supported. As shown in FIG. 3, the lever member 9 is fixed in a fully closed state slightly downward to the right, and at this time the movable weight 10 is located at the right end of the lever member 9.

A manual drive unit 12 is attached to the other protruding end of the valve shaft 3 (left side in FIG. 2) for returning the safety valve, which is in the fully open state after activation, to the fully closed state again.

In this embodiment, the valve body 1 and the valve body 2 are rectangular, but they may be circular or any other arbitrary shape.

Next, the operation of this safety valve will be explained. It is now assumed that a fluid at pressure P is acting on the left side of the valve body 2 in FIG. of
A ₁ , and the area of the valve body 2 occupying the lower part of the valve stem 3 is A ₂ , then the center of gravity of these areas A ₁ and A ₂ has a rightward force F ₁ (=P・A ₁ ), F ₂
(=P・A ₂ ) acts. However, there is always a relationship F ₂ >F ₁ , and the fluid at pressure P acts to operate the valve body 2 in the opening direction.

Also, as shown in Figure 3, the valve shaft 3 is the point of application of the forces F ₁ and F ₂ .
The distance from the center O of the valve seat 6 is l ₁ and l ₂ respectively, the distance from the center O of the reaction force R from the valve seat 6 is l, and the moving weight 1
Consider the suspension of moments around the center O, with the weight of 0 being W, the distance of its center of gravity G from the center O being S, and the line segment connecting O and G forming the horizontal axis H-H as θ. Then, the following formula holds true.

PA ₁ l ₁ +WScosθ=PA ₂ l ₂ +Rl (1) Therefore, the reaction force R is expressed by the following formula.

R=(A ₁ l ₁ −A ₂ l ₂ )P+WS cos θ/l...
...(2) From equation (2), as the fluid pressure P increases, the reaction force R,
That is, it can be seen that the force trying to close the valve body 2 decreases. If Po is the fluid pressure when this reaction force R=O, it is equal to the set pressure, and Po can be derived from equation (2) as follows.
That is, Po=WS cos θ/A ₂ l ₂ − _{A 1} l ₁ ...(3) Therefore, if the fluid pressure P tries to increase beyond the set pressure Po shown by the above equation (3), the valve body 2 The balance of is disrupted, the valve body 2 rotates counterclockwise in FIG.
Therefore, the valve actuated along the lever member 9, gradually increasing the moment to actuate the valve body 2 in the counterclockwise direction, that is, toward the open state, and gradually moved the valve body 9 to the leftmost position. At this time, the valve body 2 is maintained in a horizontal position, that is, in a fully open state.
At this time, as the fixing member 9 rotates counterclockwise, the moment for guiding the valve body 2 to the open state increases, but this is due to the unbalance of the weight of the valve body 2.
It functions to offset clockwise moments.

Thus, once the safety valve operates and becomes fully open, that is, once the valve body 2 is positioned horizontally, the fluid pressure P
Since this has no effect on the valve body 2, the safety valve is maintained in its fully open state by the weight W of the moving weight 10 as before.

In order to return the safety valve to its original state before activation, the manual drive unit 12 is driven to rotate the valve body 2 clockwise in FIG. It should be located at the right limit of .

In order to change the set pressure, as is clear from equation (3), the weight of the moving weight, the length of the lever member, the initial inclination angle of the lever member, the geometric dimensions of the valve body, and its eccentricity can be adjusted. . In addition, the above explanation was about the case where a safety valve is attached to horizontal piping.
To apply this to vertical piping, the lever member 9 may be installed parallel to the valve box center line N-N.

(Effects of the invention) The safety valve of the invention is constructed as described above, and is equipped with a butterfly valve body having an eccentric valve shaft in the valve box constituting the flow path, so that a rotational moment is applied due to an increase in internal pressure. At the same time, by using a structure in which the valve is biased in the closing direction by a weight, even a large-diameter valve can be operated with a small force, and the weight for balancing is also small and lightweight. The overall weight is small and it can be easily installed in high places.

In addition, the weight is slidable along a lever member fixed to the valve shaft of the butterfly valve body, and when the butterfly valve body is opened, the weight is moved to the other end of the lever member, thereby causing the butterfly valve body to move toward the other end of the lever member. By maintaining the open state, even if the valve body itself is heavy, the open state can be maintained without requiring a large operating force.

[Brief explanation of the drawing]

1a and 1b are longitudinal sectional views of the main parts of conventional separate safety valves, and FIG. 2 is a front view of the safety valve according to the present invention.
FIG. 3 is a partially cutaway side view. 1...Valve box, 2,102,202...Valve body, 3
... Valve stem, 8 ... Fixed weight, 9 ... Lever member, 10 ... Moving weight, F ₁ , F ₂ ... Fluid force, R ... Reaction force, W ... Self-weight of moving weight.

Claims (1)

[Scope of utility model registration request] a valve box constituting a part of a flow path; a butterfly valve body rotatably supported by a valve shaft within the valve box to open and close the flow path; and a butterfly valve body fixed to the inner surface of the valve box,
The valve seat has a valve seat with which an edge of one side of the butterfly valve body comes into contact when the valve is closed, and the valve stem is attached eccentrically to one side from the center of the butterfly valve body, and the valve stem is located outside the valve box. A lever member is attached to the lever member, and a weight is supported by the lever member and is slidable downward under its own weight along the inclination of the lever member, and when the butterfly valve body is in the closed state, the weight is attached to the lever member. The lever member is mounted slightly inclined from the horizontal so that the lever member is located on the side that urges the valve in the valve closing direction, and the butterfly valve body is moved in the opening direction by the pressure in the flow path, and the lever member is moved in the direction of inclination of the lever member. The safety valve is characterized in that as the weight changes, the weight slides toward the side that urges the butterfly valve body in the opening direction, and the open state is maintained by the weight of the weight.