JPH0218467B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cage valve in which the shape of a window provided in a cage is simplified and can be easily manufactured.

[Prior art]

This type of cage valve conventionally used for flow control is usually constructed as shown in FIG. That is, 1 is a valve main body, 2 is a partition wall provided inside the valve main body 1 and partitions the upstream flow path 10 and the downstream flow path 11, and 3 is a partition wall that is fitted into the upper opening of the valve main body 1 and has a plurality of partition walls. The upper cover is fixed with bolts 4, and a seat ring 5 is provided between the upper cover 3 and the partition wall 2.
and the cage 6 are arranged in an overlapping state. In this case, the seat ring 5 is fitted and fixed into a mounting hole 7 provided in the partition wall 2 via a packing 8, and the lower end opening communicates with the flow path 10 on the upstream side. On the other hand, the cage 6 is placed coaxially on the seat ring 5 and is pressed against the seat ring 5 by the upper cover 3, and has a plurality of windows 12 having a shape as shown in FIG. They are equally spaced in the circumferential direction. A plug 14 provided at the lower end of the valve rod 13 passing through the upper cover 3 is slidably fitted into the inner hole of the cage 6. A valve seat 15 is provided at the lower end edge of the plug 14 at the upper end opening of the seat ring 5.
An undergarment seat 16 is provided for seating on the cage 6, while an upper seating portion 18 is provided on the outer peripheral surface of the upper end for seating on a valve seat 17 provided on the inner peripheral surface of the cage 6.

Note that when the valve stem 13 is moved up and down by the actuation of a drive unit by an automatic control device or by manual operation, the plug 14 moves together with the valve stem 13 to change the opening degree of the window 12, in other words, the opening area. , thereby controlling the flow rate of the controlled fluid.

By the way, in such a cage valve, if it is desired that the flow rate characteristic, that is, the shape of the curve obtained by plotting the flow rate with respect to the position of the plug 14, be an equal percentage characteristic, the window 12 should be a large window width as shown in FIG. 1, a constant width portion A, a window width changing portion B that continues from the first constant width portion A and gradually narrows in window width as it goes downwards, and a small window width continuing from the lower end of this window width changing portion B. and a second equal-width portion C.

However, since such a window 12 has a special shape, it is not only difficult to manufacture, but also requires high precision, especially for the second constant width portion C, in order to control a small flow rate when the valve is opened at a low level. When the cage 6 was manufactured by casting, the second uniform width portion C could not be finished with high precision, and therefore it was necessary to perform post-processing using an end mill or the like. However, such post-processing is troublesome and increases manufacturing costs.

[Summary of the invention]

The present invention has been made in view of the above-mentioned points, and is such that a seat ring is integrally provided with a protrusion having a notch, the lower end of the cage is fitted onto the outer periphery of the protrusion, and the open end of the notch is connected to the cage. communicate with the window of
This cage valve has an extremely simple structure in which this notch functions as a flow rate control part when the window is open at a low valve opening, which simplifies the shape of the window, improves the manufacturability of the cage, and allows it to be manufactured at a low cost. It provides:

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 3 is a partially cutaway exploded perspective view of the cage and seat ring incorporated in the cage valve according to the present invention;
The figure is a sectional view of a main part showing the state in which the cage and seat ring are connected, and FIG. 5 is a sectional view taken along the line of FIG. 4. Components in the drawings that are the same as those in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted. A plurality of arcuate protrusions 20 are integrally provided on the upper end surface of the seat ring 5 so as to surround the valve seat 15. These protrusions 20 are provided on the same circumference, and their number matches the number of windows 12 provided on the circumferential surface of the cage 6. A notch 21 is formed between adjacent protrusions 20. In this case, the height H of the protrusion 20 is approximately equal to the height h ₁ of the second uniform width portion C (see FIG. 2) serving as the flow rate control portion when the window 12 is in the low valve opening state, and each Width D of notch 21
is approximately equal to the width d ₁ of the second equal width portion C.

On the other hand, the protrusion 2 is provided on the lower end surface of the cage 6.
A skirt portion 25 that fits on the outer circumferential surface of 0 is integrally provided. This skirt portion 25 is constituted by the lower end portion of the cage 6, that is, the lower end portion including the second equal width portion C of the window 12, and its thickness
In this example, w ₁ is the value obtained by subtracting the thickness w ₂ of the protrusion 20 from the thickness W of the cage 6 body.
As shown in FIGS. 3 and 6, each window 12 of the cage 6 has a first equal-width portion A that constitutes a flow rate control section when the high valve is open, and a first equal width section A that constitutes a flow rate control section when the middle valve is open. It does not include a second constant width portion C that constitutes a flow rate control portion when the valve is opened at a low valve opening.
This is because each notch 21 provided between the protrusions 20 of the seat ring 5 has a function as the second equal width portion C of the window 12, and the cage 6 is placed on the seat ring 5. At this time, the open end of the notch 21 that opens upward is communicated with the lower part of the window width changing portion B of each window 12, thereby connecting the first constant width portion A, the constant width changing portion B, and the second width changing portion B. A complete window 12 having equal width portions C (notches 21) and realizing equal percentage characteristics is constructed.

That is, in the present invention, the second equal-width portion C of the window 12 is replaced with a notch 21 that exists between a plurality of protrusions 20 that project from the upper surface of the seat ring 5. Therefore, the shape of the window 12 itself becomes simple, and when the cage 6 is manufactured from casting as in the past, the second uniform width portion C that constitutes the narrow flow path can be made with high precision by post-processing. There is no need for finishing, and the manufacture of the cage 6 itself is facilitated. On the other hand, since the seat ring 5 is originally manufactured by machining, it is easy to manufacture and the width of the notch 21 can be set with high precision, although the number of machining steps increases by the protrusion 20. obtain.

Note that the notch 21 may be used for tightening the seat ring 5. In this case, the seat ring 5 is pressed against the partition wall 2 (see FIG. 1) by fitting each arm 31 into the notch 21 and pressing from above using a cross-shaped tightening jig 30 shown in FIG. do it.

Further, although the above embodiment was applied to a cage valve having an equal percentage characteristic, the present invention is not limited to this, but can be applied to any device having a flow rate control section for a narrow flow path when the valve is opened at a low level. be.

〔Effect of the invention〕

As explained above, the present invention has a structure in which a protrusion body having a notch is integrally provided on the upper surface of the seat ring, and the notch functions as a flow rate control part when the window formed in the cage is opened at a low level. With this configuration, the shape of the window itself can be simplified and the manufacturability of the cage can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional cage valve.
Fig. 2 is a diagram showing the shape of the window of the cage valve, Fig. 3 is a partially cutaway perspective view of the seat ring and cage of the cage valve according to the present invention, and Fig. 4 is a schematic diagram showing the assembled state of the seat ring and cage. 5 is a sectional view taken along the line of FIG. 4, FIG. 6 is a front view of the main part of the cage, and FIG. 7 is a perspective view showing an example of a seat ring tightening jig. 1... Valve body, 2... Partition wall, 5... Seat ring,
6...cage, 12...window, 15...valve seat, 20...projection body, 21...notch, 25...skirt portion.

Claims (1)

[Claims] 1. A cage valve in which a seat ring having a valve seat inside the valve body and a cage having a window on the circumferential surface are overlapped and fixed, and a plug is slidably fitted into the cage and seated on the valve seat. , a protruding body with a notch is integrally provided around the valve seat of the seat ring, and a skirt portion that fits on the outer peripheral surface of the protruding body is integrally provided on the lower end surface of the cage, so that the notch is A cage valve, characterized in that the open end communicates with the window, and the notch serves as a flow rate control part when the window is in a low valve opening state.