JPH0412101A - Governing valve - Google Patents

Abstract

PURPOSE:To increase the resistance against bending stress by applying a latch- type, fitting structure to a connecting part between a crosshead, which is operated by an operating mechanism, and a valve rod, which drives a governing valve, thereby relieving the stress concentration in the fitted part. CONSTITUTION:In a device, which supplies high-pressure, high temperature steam, which is kept under due control, to a turbine by closing/opening the valve seat of a valve main body by using a valve (not illustrated here), which is fixed to the bottom end of a valve rod 21, a lip part 21a, whose both sides are cut to a surface width 'c', is formed on the top end of the valve rod 21. This lip part 21a is fitted into the recessed part 22a of a crosshead 22, which is loosely built into a lever-support provided to the upper part of the valve main body. After the valve rod 21 is assembled into the crosshead 22 in the direction 'B', the rod 21 is rotated by an angle of 90 deg., so that the lip part 21a of the valve rod 21 is mounted on a pedestal 'g' within the crosshead 22. Then, a valve rod pressing plate 23 is installed to the crosshead 22 by means of tap bolts 24, thereby completing the assembling work.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a steam control valve that has an improved function of preventing breakage of the valve stem by adopting a latch type fitting structure.

(Prior Art) When controlling high-pressure, high-temperature steam, such as in a steam turbine, a steam control valve is used.

Figures 8 and 9 illustrate a conventional steam control valve, which includes a stand 3 and a lever support in which a valve stem 2 can be incorporated into the upper opening of a valve body 1 that forms a passage that can withstand high-pressure steam. 4 and a spring support box 5 are provided in this order, a crosshead 6 is loosely assembled into the lever support 4, and the threaded portion 2a of the valve stem 2 is screwed into the crosshead 6, and the straight portion 2b near the upper end of the valve stem is screwed into the crosshead 6. Stop the cross head 6 and bottle 7
It's stuck.

On the upper surface of the washer 8 of the crosshead 6 located in the spring support box 5, coil springs 9 and 10 of two types of strength are installed concentrically. In addition, a pin shaft 13 provided in the middle of the lever 12 that is linked to an output shaft 11 of an operating mechanism (not shown) consisting of a servo motor or the like is connected to the crosshead 6, and a link 14 is connected to the free end of the lever 12. The upper end of the link 14 is parallel to the lever 6 and is connected to one end of the combined lever 17 so as to rotate around the support shaft 16 via the pin shaft 18. Connecting rod 19 at the other end
This is provided. A valve 20 is fixed to the lower end of the valve stem 2. 1a indicates a valve seat formed on the inner surface of the valve body 1.

In such a steam control valve, when the lever 12 is pushed upward by the output shaft 11 of the servo motor, the valve stem 2 is moved by the elastic force of the springs 9 and 1o via the crosshead 6 connected by the bottle shaft 13. It resists and is pulled upwards. As a result, the valve 2o fixed to the lower end of the valve stem 2 is separated from the valve seat 1a, and high-pressure steam is supplied to the turbine.

In this case, the lever 17 is configured to rotate around the support shaft 16 via the link 14 connected to the lever 12, so even if each member changes due to thermal expansion caused by high-temperature, high-pressure steam, unreasonable stress will not be applied. will not be given.

(Problems to be Solved by the Invention) The steam control valve described above has high pressure (approximately 248 kg/c4
In order to handle a large amount of high-temperature (approximately 538°C) steam, the design conditions have become stricter. A large excitation force is generated at points where the valve diameter is small.

This excitation force is applied to the threaded part 2a and the straight part 2b of the valve stem 2.
The vibration is transmitted to the crosshead 6 through the vibration, causing the crosshead 6 to vibrate upward, downward, leftward, and rightward. At this time, a large bending stress is generated in the threaded portion 2a, and if this continues repeatedly for a long time, there is a risk that the threaded portion 2a of the valve rod 2 that is threaded with the crosshead 6 may break. .

The present invention has been made in view of the above-mentioned points, and by changing the connection between the crosshead and the valve stem from a screw connection to a fitting connection, the stress concentration factor of the connection is alleviated, and the resistance to bending stress is reduced. The purpose of this invention is to provide a steam control valve that is reinforced.

[Structure of the Invention] (Means for Solving the Problems) The steam control valve of the present invention includes a crosshead operated by an operating mechanism and a valve stem connected to the crosshead that drives the valve. , which is characterized by the adoption of a latch-type fitting structure.

(Function) In the steam control valve of the present invention having such a configuration, the crosshead and the valve stem are connected by a latch type fitting connection, so that stress concentration is alleviated and the strength against bending stress is increased.

(Example) Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 7. In these embodiments, the structure is the same as that shown in FIG. 8 except for the connection between the valve stem and the crosshead, so only the connection between the valve stem and the crosshead will be illustrated and explained.

In FIGS. 1 to 5, reference numeral 21 is a valve stem built into the valve body, and the valve 20 (see FIG. 8) fixed to the lower end of this valve stem 21 is attached to the valve seat of the valve body. By opening and closing, high-pressure, high-temperature steam is supplied to the turbine in a controlled manner.

As shown in FIG. 3, a lip portion 21a chamfered to have a surface width C is formed at the upper end portion of the valve stem 21. As shown in FIG. This lip portion 21a is connected to the crosshead 2 that is loosely incorporated into the lever support 4 (see Fig. 8) provided at the upper part of the valve body.
2, forming a latch-type fitting structure.

This fitting structure is a feature of this embodiment, and its details will be described below.

Lip portion 21a formed at the upper end of the valve stem 21
The surface width C is l/100 to 5/1. from the width d of the fitting opening formed in the crosshead 22. It is processed to be about OOmm smaller.

In FIG. 3, the valve stem 21 is assembled from the direction of arrow A toward the direction B of the crosshead 22, and when it reaches the point, the valve stem 21 is moved clockwise (or counterclockwise) 90 degrees.
Rotate degrees.

In addition, in FIG. 3, the diameter e of the lip portion 21a formed on the upper part of the valve stem 21 is 17100~5/l[] (approximately 11 smaller than the inner diameter f machined inside the crosshead 22. In addition, the thickness h of the lip portion 21a
is l/100 to 5/100 mu from the height l from the pedestal g machined inside the crosshead 22 to the top surface.
Processed to a smaller size.

Therefore, after the valve stem 21 is rotated 90 degrees inside the crosshead 22, the lip portion 21a of the valve stem 21 is seated on the pedestal g formed inside the crosshead 22. FIG. 2 shows this seated state.

In this state, the valve stem retaining plate 23 shown in FIG. 5 is attached to the crosshead 22 with the retaining bolt 24. The final assembled state is shown in FIG.

As a result, the valve stem 2] and the crosshead 22 are integrated, and by operating the crosshead 22 by the operating mechanism consisting of the output shaft 11 of the servo motor (see Fig. 8), etc., the valve stem 2 Valve 20 formed at the lower end of
(See Figure 8) It can be opened and closed.

Further, as shown in FIG. 4, the lower surface of the lip portion 21a formed at the upper part of the valve stem 21 has a taper a.

By providing b, the incorporation into the crosshead 2 can be strengthened, and stress concentration can be alleviated.

That is, in the conventional technology, the stress concentration coefficient of the threaded portion of the valve stem is about 3 to 4 as shown in FIG. 9, but in the case of the present invention, by adopting a latch type fitting structure, The curved part becomes part b in Fig. 4, and it can be made to have a sufficiently large curvature compared to the curved part (screw bottom) formed in the threaded part, so stress concentration can be significantly alleviated. can.

Next, another embodiment of the present invention is shown in FIGS. 6 and 7.

In FIG. 6, a protrusion 31a is formed on the upper part of the valve stem 31, and the protrusion 31a has a cylindrical shape on the upper side and a thinner rectangular protrusion on the lower side. A lock hole-shaped recess 32a corresponding to the portion 31a is formed.

The protrusion 31a of the valve stem 31 is assembled into the recess 32a of the crosshead from the direction of arrow A in FIG.
As shown in the figure, the pin 33 is driven in to complete the assembly.

In this embodiment as well, the effect of alleviating stress concentration can be obtained as in the previous embodiment.

[Effects of the Invention] As described above, according to the present invention, the fitting portion between the valve stem and crosshead can be made to have a curvature that reduces stress concentration, so bending stress does not occur in the fitting portion between the valve stem and crosshead. Figure 1 of the machine box is a perspective view showing an embodiment of the present invention, Figure 2 is a perspective view showing a state in the process of assembly before attaching the valve stem retaining plate in Figure 1, and Figure 3 is a perspective view of the present invention. A perspective view showing the state of individual valve stems and crossheads according to the embodiment,
FIG. 4 is an explanatory diagram showing the dimensional relationship of a valve stem according to an embodiment of the present invention, FIG. 5 is a perspective view showing an embodiment of a valve stem press plate according to the present invention, and FIG. 6 is another embodiment of the present invention. Fig. 7 is a perspective view showing the state of the valve stem and crosshead after assembly, Fig. 8 is a vertical cross-sectional view showing a conventional steam control valve, and Fig. 9 is FIG. 9 is an enlarged vertical cross-sectional view of the connecting portion between the crosshead and the valve stem in FIG. 8;

1... Valve body 2.21.31... Valve stem 3... Stand 4... Lever support 5... Spring support box 622.32... Cross head 7... Locking pin 8... Washer 9 10... Coil spring 1]... Outer horn ◆Yu 1217...
...-Lever 13 ... Pin shaft 14 ... Link 16 ... Support shaft 19 ... Connection rod 20 ... Valve 21, a ... Lip part 22a 32a... recess 31a... protrusion

Claims (1)

[Claims] At the connection part between the crosshead operated by the operating mechanism and the valve stem connected to this crosshead and driving the valve,
A steam control valve featuring a latch-type snap-in structure.