GB2024373A

GB2024373A - Butterfly valve

Info

Publication number: GB2024373A
Application number: GB7900372A
Authority: GB
Original assignee: Maezawa Kasei Kogyo KK
Current assignee: Maezawa Kasei Kogyo KK
Priority date: 1978-06-26
Filing date: 1979-06-05
Publication date: 1980-01-09
Also published as: FR2429945B1; DE2901475A1; FR2429945A1; GB2024373B; IT1110905B; IT7919292A0; JPS556556U; JPS585167Y2

Abstract

The valve casing 1 is made of synthetic plastics and has axially extending reinforcing ribs (23), Figs. 1, 3 and 4 (not shown), formed on its outer circumferential surface. Hollow cylindrical pipe connectors 2 also of synthetic plastics are fastened to one another, as by bolts 25, with said valve casing clamped therebetween. The butterfly disc 8 is rotated by a shaft 21 through a reduction drive constituted by a threaded spindle 22 and an axially movable and rotatable member 15 having circumferential grooves 17 of varying helix angle cooperating with fixed balls 19. <IMAGE>

Description

SPECIFICATION Butterfly valve This invention relates to a butterfly valve to be used for water pipes laid down underground.

Most of conventional butterfly-valves used for the water supply and the like are made of cast iron. In executing the piping arrangement between the cast iron butterfly valve and plastic pipes, the cast iron butterfly valve is first incorporated in a valve casing made of a cast iron and then connected to the plastic pipes. However, since the valve casing is heavy in weight, the plastic pipes tend to cause cracks after the work and thus result in leakage. From time to time a worm reduction gear is used in order to retard the switching speed of the valve. In this case, the valve casing must be large in size and hence, in weight, thereby making it difficult to execute the work.

To reduce the weight of the valve casing, the valve casing made of a synthetic resin is sometimes employed. In such a device, flanges are formed at both open ends of the synthetic resin valve casing and connected by means of bolts and nuts to mating flanges of mouthpieces for coupling the water pipes to thereby establish the connection between the valve casing and the mouthpieces. However, cracks tend to occur at the flanges because the flanges must be fastened firmly in order to prevent leakage.

The present invention is directed to obtain a butterfly valve free from the abovementioned problems. In the butterfly valve in accordance with the present invention, the weight of the valve casing portion is reduced by using a valve casing made of a synthetic resin. Further, in the valve of the present invention, reinforcing ribs are formed extending and axially spacing from one another, on the outer circumferential surface of the valve casing, thereby preventing damages of the valve casing and the flanges of the hollow cylindrical mouthpieces of a synthetic resin abutting to the valve casing arising from the exceeding flangefastening force in the axial direction.

Other objects and features of the device of the present invention will become more apparent from the following detailed description to be read in conjunction with the accompanying drawings: Figure 1 is a side view showing an embodiment of a valve of the present invention; Figure 2 is a longitudinally sectional side view showing the valve; Figure 3 is a side view of a valve room of the valve; Figure 4 is a side view of the valve room in the other embodiment of the present invention; Figure 5 is an exploded view of its inner cylinder; and Figure 6 is a diagram showing the relationship between the flow rate and the opening of a valve plate.

in Figure 1 reference numeral 1 represents a hollow cylindrical valve casing made of a synthetic resin. On the outer circumferential surface of the valve casing, a plurality of reinforcing ribs 23 are formed equidistantly spacing from one another and extending axially through the total length of the valve casing or the length shorter than that. An annular valve seat 6 of an elastic material is fitted onto the inner circumferential wall of the valve casing 1 and its edges at both ends are bent outwardly and fitted into the both open ends 5, 5 of the valve casing 1. To said edges of the valve seat 6, inner open ends 7,7 of the mouthpieces 2, 2 are abutted so as to hold the valve casing 1 therebetween. Flanges 24, 24 provided on the outer circumferential surface of the mouthpieces 2, 2, respectively, are fastened by using bolts 25 and nuts 26.Each bolt 25 is arranged at the intermediate portion of the adjacent reinforcing ribs 23 and the height of each rib 23 is designed not lower than the center level of each bolt 25.

The reinforcing ribs 23 may be arranged at portions near the both sides of each bolt 25 as shown in Figure 4.

Rubber rings 4, 4 are fitted into annular grooves 3, 3 formed on the inner circumference in the proximity of the outer ends of the mouthpieces 2, 2, respectively. A swelling portion is formed on a disc-like valve plate 8 made of a synthetic resin and fitted to the valve seat 6 and extends in the direction of diameter.

A valve shaft 9 is inserted into this swelling portion of the valve plate 8 engages with a knurled groove 10 formed around the outer circumference of the valve shaft 9 and is secured thereto. The lower end of the valve shaft 9 is supported by the lower bottom portion of the valve casing 1 via a bearing 11 and its intermediate portion is supported by the upper wall of the valve casing 1 via a bearing 1 2. The upper end of the valve shaft 9 penetrates through the upper wall of the valve casing 1 and extends to protrude into an axial cylinder 13 that is formed integrally with, and protrudes above, the valve casing 1.The valve shaft 9 is further inserted into a hollow cylindrical rotary moving member 1 5 capable of moving up and down inside the axial cylinder 13 and is allowed to mate with a key groove 1 6 formed on the inner circumferential wall of the moving member 1 5 and extending in the axial direction by means of a key (not shown).

A bolt 22 is brought into screw engagement with the upper portion of the moving member 15 and its upper end protrudes upward beyond a lid 14 at the upper end of the axial cylinder 13 and is interconnected to a rotary handle shaft 21. Screw slots 1 7 having a pitch greater than that of the screw of the abovementioned bolt 22 is cut on the outer circumference of the moving member 1 5 in such a manner that the lead angle of the screw slot 1 7 becomes great as represented by a1 in Figure 5 when the opening of the valve plate 8 rotates in the range of from 0 to about 20 degrees and becomes small as represented by a in the range of from 20 to 90 degrees. It goes without special noting in this instance that the lead angle a2 is greater than that of the bolt 22.Balls 19, 19 are fitted into the screw slots 1 7 of the moving member 1 5 from through-holes 1 8, 18 that are formed respectively to penetrate through the circumferential wall of the axial cylinder 13. Set screws 20, 20 are screwed into the through-holes, 18, 18 so as to bring these balls 19, 19 into pressing contact with the screw slots 1 7.

The explanation will now be given on the action of this embodiment of the butterfly valve in accordance with the present invention.

Water pipes a, a made of a synthetic resin are connected to the right and left mouthpieces 2, 2 via the rubber rings 4,4 respectively and laid down underground.

Deviation of axis between the valve casing and the water pipes due to the soil pressure and the like, if any, and oscillation due to the water hammer can be absorbed by the elastic deformation of the rubber rings 4, thereby enabling to prevent damages of the synthetic resin valve casing and water pipe.

When the handle shaft 21 is turned, the bolt 22 directly connected to the handle shaft 21 is also turned so that the moving member 15 screwed to this bolt 22 moves up and down while rotating.

Since the pitch on the outer circumference of the moving member 1 5 is greater than that of the screw of the bolt 22, however, the moving member 1 5 is guided by the screw slots 1 7 and the ball 1 9 fitted thereto and rotates at a speed slower than that of the bolt 22. For example, when the bolt 22 turns 8 rounds, the valve shaft 9 does 1/4 rounds. Smooth rotation is ensured for the moving member 1 5 by the roller action of the ball 19. At this time the valve shaft 9 engaged with the moving member 1 5 by the key rotates in response to the rotation of the moving member 1 5 without causing the movement in the vertical direction whereby the valve plate 8 causes the opening or closing action.

Since the lead angles a1 and a2 of the screw slot 17 of the moving member 1 5 satisfy the relation a1 > a2 as shown in Figure 5, the valve plate 8 opens gradually from 0 to 20 degrees as shown in Figure 6 because the lead angle cg, is large, and opens rapidly from 20 to 90 degrees till it reaches the full admission indicated by chain line in Figure 2 because it is guided by the screw slot 17 having the lead angle a2 smaller than the lead angle sir1. When the valve plate 8 opens to about 20 degrees, the lefthand ball 19 in Figure 2 engages with the upper screw slot 1 7 in Figure 5 and rotates from 20 to 90 degrees whiie being guided by the mutually parallel screw slots 1 7 and 1 7. When the valve plate 8 is closed, its speed of rotation is fast from 90 to 20 degrees and is slow from 20 to 0 degree as the valve plate is guided by the screw slots 1 7 and the balls, thereby preventing the water hammer phenomenon.

As described in the foregoing paragraph, since the valve casing is made of a synthetic resin the weight of the valve casing portion is reduced, so that the mouthpieces connected thereto and the plastic pipes connected to the mouthpieces are prevented from being applied excessive force thereon. Further, axially extending reinforcing ribs are formed on the outer circumferential surface of the synthetic resin valve casing spacing from one another, so that the flange-fastening force is limited by the reinforcing ribs and the valve casing as well as the flanges are prevented from being damaged arising from the excessive flangefastening force in the axial direction.

The embodiment described herein is similar, particularly in terms of the rotation of the valve shaft or spindle 9 by the bolt 22, to the disclosure of our co-pending Patent Application No.

47333/78 (Serial No. 2 012 396).

Claims

1.-A butterfly valve comprising; a hollow cylindrical valve casing made of a synthetic resin; axially extending reinforcing ribs formed on the outer circumferential surface of said valve casing; a valve plate made of a synthetic resin and fitted inscribedly to a valve seat lined onto said valve casing; a valve shaft connected to said valve plate, pivoted turnably to said valve casing and having one end thereof protruding from said valve casing; hollow cylindrical mouthpieces made of a synthetic resin, abutted to the both open ends of said valve casing so as to hold said valve casing therebetween and having flanges on the outer circumferential surfaces thereof; and fastening means for fastening said flanges of the mouthpieces in the axial direction thereof.

2. The butterfly valve as defined in claim 1 including further a rotary moving member engaged with the outer circumferential surface of said valve shaft turnably and slidably in the axial direction, retarding the rotation of an operation handle shaft and transmitting it to said valve shaft.

3. The butterfly valve as defined in claim 1 including further rubber rings fitted into the inner circumferential surfaces of said mouthpieces in the proximity of its respective outer ends.

4. The butterfly valve as defined in any preceding claims 1-3 wherein said rotary moving member is screwed to said handle shaft; a key formed protrusively on the outer circumferential surface of said valve shaft engages a key groove formed on the inner circumferential surface of said rotary moving member to extend in the axial direction; a screw slot having a pitch greater than that of a screw of said handle shaft is defined on the outer circumferential surface of said rotary moving member; and an engaging element protruding from the inner circumferential surface of an axial cylinder formed to protrude from said valve casing engages with said screw slot.

5. Butterfly valve, substantially as hereinbefore described with reference to the accompanying drawings.

6. A butterfly valve comprising a hollow cylindrical valve casing made of a synthetic plastics material, longitudirially extending reinforcing ribs being integrally moulded on the external circumference of the valve casing, a valve member made of a synthetic plastics material and mounted on a valve shaft or spindle which is pivotally mounted with respect to the valve casing and which projects from the valve casing, two hollow cylindrical mouthpieces disposed at respective open ends of the valve casing, each mouthpiece disposed at respective open ends of the valve casing, each mouthpiece having a radially projecting external flange on the end of the mouthpiece adjacent the valve casing, and clamping means which clamp the flanges of the mouthpieces together with the valve casing therebetween.

7. A butterfly valve according to Claim 6, wherein the clamping means comprises bolts, the centres of which are arranged on a pitch circle centred on the aligned longitudinal axes of the valve casing and the hollow mouthpieces, the ribs projecting radially beyond the pitch circle and being spaced circumferentially from the locations of the bolts.