CA1124615A - Check valve - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A bearing arrangement for valve pins which are of a material harder than the valve body, afforded by one or more plates of a material of hardness similar to 5 the material of the pins supported in the valve body.

Description

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i~CHECK VALYE
This application is a divisional application with respect ~o patent application 333,984.
This inven~ion is concerned generally with valves 5 and more particularly with certain constructional improvements applicable to check valves of the type having complementary oppositely pivoting yalYe members or plates, sometimes referred to as "flappers".
Check valves of this type are described for 10 example, in United States patents 1413371, 2877792, 3026901, 3452778, 3538946 and 3831628. They typically incorporate one or more helical torsional springs which are mounted on the common hin~e pin for the valve plates and bias the plates to their closed 15 position.
A difficulty encountered with certain valves, and particularly with check val~es of the type referred to, arises from the use of steel val~e pins in a cast iron body. The pins, bsing much harder, perhaps three times 20 harder, than the body have a tendency to relatively quickly washout their locality in the case iron until eventually the valve components dissociate. ~
conventional approach to this problem would be to provide a steel bushing or plug to increase the bearing surface 25 between the steel and cast iron but this approach has not always proven economically viableO
In a second aspect, the inYention accordingly provides a valve comprisin~:
a body with a passageway therethrough at least in 30 part defined by an internal wall of said body.
a Yalve asse~bly havIng a condition in which it closes off said passageway;
a valve pin, being part of said assembly, of a material harder than the ~aterial of said body, said pin 35 extending from said internal wall across the passageway î

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and a pl~te of a material of hardness s:imilar to the material of the pin, which plate is supported in said body and affords a bearing for said pin.
The bearing plate may be mounted in a recessed seat formed on the internal wall of valve boay, It may be cast in situ in the ~alve body or may be inserted after~asting into a complementary seat formed in the body during casting.
Both ends of the valve pin may be supported in respective plates of a hardness similar to the pin. A
sleeve is advantageously moun-ted on the pin with its ends abutting, and thereby properly spacin~ and retaining, the respective plates.
The invention will be further described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is an axial cross-section of a check valve constructed'in accordance with the invention; and Figure 2 is a cross-section on the line 2-2 in Figure 1, one valve pin being cut away for,purposes of illustration.
The illustrated check ~alve 10 includes an annular cast iron valve body 12 flanged at 14, 15 for connection 25 into a liquid supply line, Body 12 bounds a flow passageway 16 ha~ing two parts 16a, 16b communicated by a pair of openings 17, 17a separated by a post 20 being an integral part of body 12. Disposed in a common plane about openings 17j 17a is a suitably finishea or faced 3~ valve seat afforded by an annular shoulder 18 and by a flattened face 22 of post 20 Valve assembly 25 is mounted in portion 16a o~
passageway 16 on a pair of steel pins 26~ 28 w,hich extend parallel to post 20 through the axis of passageway 35 16. Pins 26, 28 locate in respective pairs of opposed complementary bores 30, 32 in the ~alve body which extend to the outside of the body but are closed by sealing ~` ''` '' '~'' ~" '''' '` ~''`'~'~- -~ - ~ - ., ~... ....

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_4--plugs 34. The pins fit fairly loosely into bores 30, 32 and ~ ~ore precise beariny is afforded by apertures in respective rectangular steel plates 36, 37. Plates 36, 37 are set over bores 3~, 32 into complementary 5 seats comprised of slots 38, 39 in the inner wall 40 of the valve body which bounds portion 16a of passageway 16.
It will be seen that each of plates 36, 37 has two apertures, one for each of the pins 26, 28. The plates may have been cast in situ in the body or may be 10 simply placed in position after casting of the body wi~h the requisite slots. They are retained in place by a sleeve 41 mounted on pin 28 with its ends abutting the respective plates.
It will be seen that a substantial increase in 15 bearing surface between the steel and the cast iron, with advantageous irregular boundaries, has been provided with minimal usage of steel, and certainly at lower cost than conventioanl steel bushings or plugs. In this way, the early washout and e~rentual-valve dissociation which 20 would be expected with the steel pins, steel being substantially, harder than cast iron, are largely prevented, In this case, the valYe closure members comprise a pair of semi-circular plates 42, 43 hingeably mounted 25 on pin 26 by way of respectiYe pairs of collared lugs 44, 45. Biasing means in the form of a helical torsional spring 50 is pro~ided to bias valve plates 42, 43 into their closed positions a~ainst the valve seat about openings 17, 17a. In use, fluid flow acting from 30 passageway portion 16b opens the yalve by pivoting plates 42, 43 against spring 50 oppositely about pin 26 to an open position longitudinally within passageway portion 16a against pin 2~, Spring 50 comprises a single lenyth of spriny wire ~5 coiled into three windings and having extended portions or legs 52, 53 at its free ends engaging against the rear faces of val~e plates 42, 43, Two of the windings 54, . ~ . .. ~, .. ,, ~ .. . .. . . . . .

55 have an equal number of turns and are under equal tors~on, These windings are coaxial and are suppor~ed on the hinge pin 26, while the thirdwinding, 56, has substantially fewer turns about an axis offset from the 5 axis of windings 54, 55. Winding 56 is looped about sleeve 41 and is thus supported by pin 2~.
It is found that the divided winding construction of spring 50 is effective to substantially prevent dissipation of stored compressive energy from either of 10 the respective windings 54, 55 to the other, and, accordingly, the ~iasing force imparted by windings 54, 55 remains effectively equal. In this way, synchronous closing of the two valve plates is sustained, even with prolonged operation of the valve. The unitary 15 form of spring 50 is an advantage in assembly of the valve, while the support of the intermediate winding 56 from pin 28 is secure and reliable.

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Claims (5)

CLAIMS:

1. A valve comprising:
a body with a passageway therethrough at least in part defined by an internal wall of said body;
a valve assembly having a condition in which it closes off said passageway;
a valve pin, being part of said assembly, of a material harder than the material of said body, said pin extending from said internal wall across the passageway; and a plate of a material of hardness similar to the material of the pin, which plate is supported in said body and affords a bearing for said pin.

2. A valve according to claim 1 wherein the plate is mounted in a recessed seat formed in said internal wall.

3. A valve according to claim 1 or 2 comprising a pair of said plates affording a bearing for the respective ends of the valve pin.

4. A valve according to claim 3 further comprising a sleeve mounted on the pin with its ends abutting the respective plates.

5. A valve according to claim 1 or 2 wherein said body is of cast iron and said valve pin is of steel.