JPH0640384Y2 - Check valve mounting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a check valve, and more particularly to a novel structure for swingably mounting a valve body on a swing arm in a valve box of the check valve. is there.

BACKGROUND OF THE INVENTION Check valves are widely used in various industrial fields to allow fluid to flow in only one direction and prevent it from flowing in the other direction.

2A and 2B show a typical structural example of such a check valve 1. As is well known, a valve box 2 having a valve lid 3 has a fluid inlet passage 2a and a fluid inlet 2a. The outlet passage 2b is formed, and the valve body 5 attached to the swing arm 4 pivotably supported in the valve box 2 has a fluid inlet passage 2a.
When there is no flow between the outlet passage 2b and the outlet passage 2b, it takes a fully closed position as shown in FIG. 2A, and when a flow occurs, it takes a full open position as shown in FIG. It is adapted to collide with a stopper portion 6 formed on the inner surface of the valve box 1.

Further, when the above-mentioned check valve 1 is used in, for example, a thermal power plant with many load fluctuations, in the process from startup of the plant to a steady operation state, there is a certain flow rate condition of a fluid such as steam. Then, a fluid lift force that stably holds the valve body 5 in the fully opened state cannot be obtained, the valve body 5 vibrates near the fully opened position, and the valve body head 5a temporarily collides with the stopper portion 6 repeatedly. Chattering may occur.

When the valve body head portion 5a collides with the stopper portion 6 in this way, most of the kinetic energy of the valve body 5 is absorbed by the stopper portion 6. However, in the check valve 1, since the valve body 5 is loosely fitted to the swing arm 4, as shown in FIG. 3, when the valve body head 5a collides with the stopper portion 6, the valve body 5 Since the moment of inertia M with respect to the rotation center “0” acts on the valve body 5, the valve body 5 tries to rotate in the direction in which the moment of inertia M acts even after colliding with the stopper portion 6.

The moment of inertia M is a cylindrical portion that receives the bearing portion 4a of the swing arm 4, that is, the head portion 5a of the valve body 5.
Since it is received by the 4a, the outer surface 5b of the valve body 5 and one end surface 4b of the bearing portion 4a of the swing arm 4 are in contact with each other as shown in the figure, or the nut 7 cooperates to move the valve body 5 to the swing arm. As shown by the arrows, reaction forces F ₁ and F ₂ are generated at the position where the other end surface 4c of the bearing portion 4a of the swing arm 4 is in contact with the washer 8 that is fixed to the shaft 4.

On the other hand, in order to attach the above-mentioned valve body 5 to the swing arm 4, as shown in FIG. 4, the head portion 5a of the valve body 5 has a large-diameter portion 5a 'fitted to the bearing portion 4a of the swing arm 4. , A small-diameter screw portion 5a ″ extending from the large-diameter portion, and a nut 7 is screwed onto the small-diameter screw portion 5a ″, and is pressed against the end surface 4c of the bearing portion 4a of the swing arm 4 via a washer 8. It has become.

[Problems to be Solved by the Invention] However, in the mounting structure of the valve body 5 as described above, as described with reference to FIG. 3, the reaction force F is generated by the rotation of the valve body 5 due to the moment of inertia M. _{When 1} and F ₂ are generated, the reaction force F ₂ of the reaction force is the root of the small diameter screw portion 5a ″ of the valve body head 5a via the washer 8, that is, the large diameter portion 5a ′ and the small diameter screw portion 5a ″. It acts as a bending force at the boundary part between and, and the largest impact bending stress is generated at this boundary part. Further, since the above-mentioned boundary portion is a stepped portion between the large diameter portion and the small diameter screw portion, stress concentration occurs in addition to the impact bending stress at the boundary portion, and the product of the impact bending stress and the stress concentration coefficient is calculated. Peak stress occurs.

As can be seen from the above, the conventional valve body mounting structure has a problem in its strength, and in the worst case, the valve body head is broken,
Since the valve body may be separated from the swing arm,
Improvements were strongly desired.

Accordingly, it is an object of the present invention to provide a valve body mounting structure for a check valve that has a significantly improved strength.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a valve having a swing arm whose rotation is restricted by a stopper portion, and a head portion fitted to a cylindrical bearing portion of the swing arm. In a valve body mounting structure in a check valve, comprising a body and a fixing member for fixing the head portion of the valve body to the bearing portion, the head portion is provided on the bearing portion so as to slightly project from the bearing portion. The fixing member includes a large-diameter portion to be fitted and a small-diameter portion extending from the large-diameter portion, and the fixing member contacts the end surface of the bearing portion while surrounding the portion of the large-diameter portion protruding from the bearing portion from the outside. It is characterized in that it is fixed to the small diameter portion in a contact state.

[Operation] When the valve body is attached to the swing arm by the above-described valve body attachment structure of the present invention, when the swing arm is restricted from pivoting due to collision of the head portion of the valve body with the stopper,
Reaction force due to rotation of valve body due to moment of inertia M at the time of collision
Although F ₁ and F ₂ are generated, the extension of the fixing member (nut) is attached to the large diameter part of the valve head at the part where the reaction force F ₂ that has generated the largest impact bending reaction force in the past acts. Since they are fitted together, the impact bending reaction force is alleviated. Further, since the above-mentioned portion is located at a position crossing the large-diameter portion and has no step, no stress is concentrated.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding portions.

The present invention relates to a check valve, and in particular, provides a structure for attaching the valve body to a swing arm, but the detailed structure of the check valve itself is not the gist of the present invention. For example, see FIGS. 2A and 2B. The description can be omitted because it can be the same as that described in relation to.

According to the preferred embodiment of the present invention, the valve body mounting structure is constructed as shown in FIG. That is, in FIG.
The swing arm 4, which can be rotatably attached to the valve box (see FIGS. 2A and 2B), has a cylindrical bearing portion 4a at its tip,
The head portion 5a of the valve body 5 is fitted in the bearing portion 4a. The valve body head portion 5a has a large diameter portion 5a 'and a small diameter screw portion 5a "(small diameter portion) extending from the large diameter portion 5a'.

In the prior art, the axial dimension or length of the large-diameter portion 5a 'was substantially equal to the length of the bearing portion 4a of the swing arm 4, but in the present invention, it is substantially smaller than the length of the bearing portion 4a. It is formed to be long and protrudes from the end surface 4c of the bearing portion 4a.
Further, the valve body head having the large diameter portion 5a ′ thus projected.
The nut (fixing member) 7 provided for fixing the 5a to the swing arm 4 has a cylindrical extension 7a extending toward the bearing 4a, and the end face of the extension 7a is the end face of the bearing 4a.
It is configured to abut the 4c. The nut 7 is fixed to the bearing portion 4a of the swing arm 4 by welding, as shown by reference numeral 9, after being screwed onto the small diameter screw portion 5a ″.

In this embodiment, the end surface 7b of the extension portion 7a of the nut 7 comes into direct contact with the end surface 4c of the bearing portion 4a, but an appropriate washer may be used, or the extension portion 7a may be almost The corresponding portion may be a washer that is separate from the nut body. Further, the nut 7 has the small-diameter threaded portion 5a ″ as described above.
Since the small-diameter screw portion and the nut do not have to be threaded members because they are fixed to each other, for example, key grooves are formed at corresponding positions on both sides, and after inserting a key into the key groove, Appropriate fixing means for fixing the key by welding may be adopted.

When the valve body 5 is attached to the swing arm 4 by the above-described valve body mounting structure of the present invention, the stopper portion 6 (see FIG. 3)
The reaction forces F ₁ and F ₂ are generated by the rotation of the valve body 5 due to the moment of inertia M at the time of a collision, but the reaction force F ₂ that has generated the largest impact bending stress in the past acts on the part (indicated by reference numeral 10). ), The extension portion of the nut 7 is attached to the large diameter portion 5a 'of the valve head portion 5a.
Since 7a is fitted, the impact bending stress is relieved. Also, since there is no step in the above-mentioned part 10,
Stress is not concentrated.

[Advantage of Invention] Therefore, according to the present invention, not only the impact bending stress in the portion receiving the reaction force F ₂ is alleviated but also there is no stress concentration in the portion, so that the strength is greatly improved and the breakage accident is prevented. It is possible to provide a valve body mounting structure that does not have a valve body.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of an essential part of a valve body mounting structure according to a preferred embodiment of the present invention, and FIGS. 2A and 2B show a fully open state and a fully closed state of a typical check valve valve body. FIG. 3 is a schematic sectional view showing each, and FIG. 3 is a sectional view for explaining a vibration phenomenon at the time of full opening of a valve body mounted on a swing arm by a conventional valve body mounting structure, and FIG. 4 is shown in FIG. It is a principal part sectional view of the conventional valve body mounting structure. DESCRIPTION OF SYMBOLS 1 ... Check valve, 4 ... Swing arm 4a ... Cylindrical bearing part, 4c ... End surface of bearing part 5 ... Valve body, 5a ... Head of valve body 5a '... Large diameter part of valve head 5a "... Small diameter part of valve head (small diameter screw part) 6 ... Stopper part, 7 ... Fixing member (nut)

Claims (1)

[Scope of utility model registration request] 1. A swing arm whose rotation is restricted by a stopper portion, a valve body having a head portion fitted into a cylindrical bearing portion of the swing arm, and the head portion of the valve body serving as the bearing portion. In a valve body mounting structure in a check valve including a fixing member for fixing, the head portion has a large diameter portion that fits into the bearing portion so as to slightly project from the bearing portion, and a small diameter portion that extends from the large diameter portion. The fixing member is fixed to the small diameter portion in a state of being in contact with the end surface of the bearing portion while surrounding the portion of the large diameter portion protruding from the bearing portion from the outside. A feature of the valve mounting structure for check valves.