GB2096281A

GB2096281A - Non-return valve

Info

Publication number: GB2096281A
Application number: GB8204524A
Authority: GB
Original assignee: Gustav F Gerdts KG
Current assignee: Gustav F Gerdts KG
Priority date: 1981-04-07
Filing date: 1982-02-16
Publication date: 1982-10-13
Also published as: FR2503318A1; DE3113938A1; JPS57179478A

Abstract

A non-return valve has a valve casing (1), two closure parts (5, 6), which can pivot about two juxtaposed axes and a closing leg spring for each closure part (5, 6). On the outflow side each closure part (5, 6) carries two trunnions. The leg springs are arranged on two bearing spindles (15, 16) located coaxially between the trunnions. Supports (10) for the bearing spindles (15, 16) are provided in the valve casing (1). This permits a low flow resistance, even in the case of small nominal diameters. <IMAGE>

Description

SPECIFICATION Non-return valve This invention relates to non-return valves and is particularly concerned with a non-return valve of the type having a valve casing, two closure parts which can pivot about juxtaposed axes and a closing leg spring arranged to act on each of the closure parts.

Owing to the double axiality, i.e. a separate pivoting axis for each closure part, in the case of such non-return valves the closure parts do not impede one another, which has a particularly positive effect in the case of a vertical axial path.

Owing to the fact that each closure part has its own leg spring and the considerable spring length made possible through mounting on two axes, it is possible to keep particularly low the rise in the spring closing moment on opening the non-return valves. Owing to the substantial coaxiality of the pivoting axis of the particular closure part and the coiling axis of the associated leg spring, relative movement between the leg spring and its bearing surface on the closure part, as well as resulting friction and wear, are prevented. Non-return valves of this type have a particularly favourable opening and closing behaviour.

In a known construction of such non-return valves (German Gebrauchsmuster No.

79 29 136) the necessary width of the web in the valve casing is predetermined by the diameter of the bearing bushes of the closure parts, as well as the necessary width of the valve seat portion on the web. In the case of large nominal widths, such non-return valves are characterized by a very limited flow resistance. However, in the case of smaller non-return valves, there is a relatively wide web compared with the nominal diameter and a correspondingly increased flow resistance.

The present invention aims to provide a nonreturn valve of the aforementioned type which, whilst maintaining the double axiality permits a particularly limited flow resistance, even in the case of small nominal diameters.

According to the invention, there is provided a non-return valve having a valve casing, two closure parts co-operating with a valve seat in the valve casing and pivotable at their facing edges about two juxtaposed axes, and at least one closing leg spring for each closure part, the coiling axes of the leg springs being substantially coaxial to the pivoting axes of the closure parts, wherein the pivoting axes of the closure parts are arranged on the outflow side behind the said closure parts.

Owing to the positioning of the two axes on the outflow side behind the closure parts instead of between the latter, the closure parts can now be juxtaposed with a very limited spacing and, as a result, the web can be particularly narrow so that a limited flow resistance is obtained. There is no need to renounce the constructional principle of double axiality.

Preferably, each closure part carries on its outflow-side end face two trunnions acting as pivoting axes and mounted at their ends projecting laterally from the closure parts in the valve casing, the leg springs being located on respective bearing spindles provided between the closure part-side ends ot the trunnions ot both closure parts and supports for the bearing spindles being provided in the valve casing. This arrangement leads to a further significant improvement in that instead of thick-walled bearing bushes with a correspondingly large external diameter on the closure parts, trunnions with a smaller diameter are used. The axial lines of the trunnions can be positioned particularly close to the adjacent closure part, as well as to the seat.Through positioning the trunnions close to the seat, a radially dutwardly directed movement component of the outer edge of the closure part is prevented during pivoting. This permits particularly large closure parts and as a result a large passage cross-section in the valve seat, without impairing the freedom of pivoting of the closure parts by outflow-side connecting parts or casing constrictions. Through positioning the axial lines close to the edge of the closure part, in the open position the closure parts are largely in the wake of the web. This leads to a particularly low flow resistance of the non-return valve. There are still two bearing spindles for receiving the leg springs.

It is also preferred that the supports are constituted by two brackets held on the valve casing on the outflow side behind the closure parts and extending longitudinally over and beyond the trunnions, said brackets having at their free ends traverse arms which project between the facing ends of the trunnions adjacent to the closure parts and hold the bearing spindles. This arrangement provides a particularly advantageous constructional principle for the supports of the leg spring bearing spindles.

According to a preferred embodiment of the invention, the brackets constitute the webs of two U-shaped frames fixed in each case by one leg to a wall of the valve casing and have bearing points for the trunnions whilst the other legs form said transverse arms and hold the bearing spindles.

In order to prevent twisting of the U-shaped frames, the said one legs of the frames are desirably arranged to rest on respective shoulders formed on the valve casing. For fixing the Ushaped frame permitting a very close juxtapositioning of the trunnions, each U-shaped frame preferably has, in the casing-side leg between the bearing point for the trunnions and its web, a locating hole for a respective fixing screw.

A particularly simple construction for the bearing points for the trunnions of the closure parts is achieved by providing the said one leg of each U-shaped frame with two locating holes for the trunnions.

Preferably, the valve casing is provided with a supporting shoulder for the trunnions and the said one legs of the U-shaped frames have, in each case, two locating slots for the trunnions which are open towards the supporting shoulder and which serve as said bearing points. This arrangement is particularly advantageous in the case of a valve casing constricted on the outlet side, because the U-shaped frame can be inserted in the valve casing independently of the closure parts and can be placed from above over the trunnions.

The bearing spindles may be fixed, at one end, to one of the supports which makes fitting particularly easy, because through the two bearing spindles for the leg springs and one support forming a fixed unit, the fitting of the said parts in the valve casing is made particularly easy. The bearing spindles are desirably axially displaceablv mounted on the other support which provides the possibility of inserting the bearing spindles with the leg springs and both supports as a single unit into a valve casing constricted on the outlet side.

Planar supporting surfaces for the end faces of the trunnions, which are particularly advantageous in the case of a vertical axial path, can be reaiized in a particularly simple manner by arranging spacing plates between the said one legs of the Ushaped frames and the wall of the valve casing.

The invention will now be further described, by way of example, with reference to the drawings, in which Fig. 1 is a section through one embodiment of a non-return valve according to the invention taken on the line I-I in Fig. 2; Fig. 2 is a part-sectional plan view of the nonreturn valve shown in Fig. 1; Fig. 3 is a section taken on the line Ill-Ill in Fig. 1 in the direction of the arrows; and Fig. 4 is a cutaway portion of a modification of the non-return valve shown in Fig. 1.

Referring to the drawings, a flat, disk-shaped valve casing 1 has a web 3 in its inflow-side inner space 2. In the outflow-side inner space 4, which tapers towards the outlet (Figs. 1 to 3) are juxtaposed two semi-circular closure parts 5, 6, whose facing edges have only a limited spacing behind the web 3. The closure parts 5, 6 cooperate with a valve seat 7 in the valve casing 1.

On their outflow-side end face each of the two closure parts 5, 6 carries oppositely directed trunnions 8, 9. In the radial direction the latter on one side terminate flush with the edge of their closure part 5, 6. In the longitudinal direction they project laterally beyond their closure part 5, 6.

The valve casing 1 contains two U-shaped frames 10, 1 whose open end faces the closure parts 5, 6. In each case they are fixed by one leg 12 to the valve casing 1 and at the same time form bearing points for the trunnions 8, 9. A web 14, which in each case connects the two legs 12, 13 of the U-shaped frame 10 or 1 1, on the outflow side extends spacedly and longitudinally over the trunnions 8, 9 and serves as a pivot stop for the closure parts 5, 6 in the open position. The second leg 1 3 of each U-shaped frame 10 or 11 projects between the opposite ends of the trunnions 8, 9.On the legs 13, both U-shaped frames 10, 11 carry two bearing spindles 15, 16, extending substantially coaxially to the trunnions 8,9. The coils of two leg springs 17 are located on each bearing spindle 15, 1 6. The latter bear by their short legs on the, in each case, adjacent bearing spindle 15 or 16, whereas their long legs act in the closing sense on the closure part 5 or 6 mounted coaxiallywith the particular leg spring 17. Between the web 14 and the trunnions 8, 9, the U-shaped frames 10, 11 have in their leg 12 a locating hole 1 8 for fixing by means of a fixing screw 19 which passes radially through the wall of the valve casing 1.Between the leg 12 and the wall, there is a spacing plate 20 which, in the case of a vertical pivoting axis (Fig. 2), serves as a planar, axial step bearing for the lower trunnions 8, 9. At the front, the leg 1 2 rests on a supporting shoulder 21 of the valve casing 1 positioned a limited distance below the trunnions 8, 9. Each leg 12 also has two juxtaposed locating slots 22 for the trunnions 8, 9 of both closure parts 5, 6 and which are open towards the supporting shoulder 21.

One end of the two bearing spindles 15, 16 is in each case connected to the leg 13 of the Ushaped frame 1 To this end, the bearing spindles 15, 1 6 can be screwed to the frame 11 (as shown in Fig. 3), welded or pressed into the same, whilst the bearing spindles 1 5, 1 6 and U-shaped frame 11 can also be constructed as a one-part casting.

The, in each case, other end of the bearing spindles 15, 1 6 is mounted in axially displaceable manner in through-bores in the leg 13 of the frame 10.

The non-return valve is assembled as follows.

Firstly, the two closure parts 5, 6 are inserted in the valve casing 1. Leg springs 1 7 are mounted on the bearing spindles 15, 1 6 fixed to the U-shaped frame 11 and drawn on to the free ends of the bearing spindles 15, 1 6 is the U-shaped frame 10 to such an extent that the bearing and spring constructional group formed from part 10, 11, 1 5, 1 6 and 1 7 can be inserted through the narrowed outlet opening in the valve casing 1. In the inner space 4, the U-shaped frames 10, 11 are moved apart and their legs 12 with their locating slots 22 are placed over the trunnions 8, 9.Spacing plates 20 are placed between the legs 12 and the wall of valve casing 1 and then the two U-shaped frames 10, 11 are fixed to the casing 1 by screws 19.

In the construction according to Fig. 4 the outflow-side inner space 4 of the valve casing 1 is cylindrical. The legs 12 of the U-shaped frames 10, 11 contain locating holes 23 and rest axially on a shoulder 24 of the valve casing 1 located in the vicinity of the valve seat. This axial support defines the fitting position and prevents any rotary movement of the U-shaped frames 10, 11 about the fixing screws 1 9 in the case of a possible assymmetrical loading by the closure parts 5, 6.

The closure part mounting according to the invention on the outflow side behind the closure parts 5, 6 and therefore close at the edge to the adjacent closure parts 6, 5, as well as at a minimum distance from the valve seat 7, permits in spite of the double axiality a particularly narrow web 3 in the valve casing 1 and leads to a particularly low flow resistance of the valve, even in the case of smaller nominal diameters. In addition, an advantageous large fitting length is available on the bearing spindles 1 5, 1 6 for the leg springs 17, which are separate for each closure part 5, 6.

Claims

1. A non-return valve having a valve casing, two closure parts co-operating with a valve seat in the valve casing and pivotable at their facing edges about two juxtaposed axes, and at least one closing leg spring for each closure part, the coiling axes of the leg springs being substantially coaxial to the pivoting axes of the closure parts, wherein the pivoting axes of the closure parts are arranged on the outflow side behind the said closure parts.

2. A non-return valve according to claim 1, wherein each closure part carries on its outflowside end face two trunnions acting as pivoting axes and mounted at their ends projecting laterally from the closure parts in the valve casing, the leg springs being located on respective bearing spindles provided between the closure part-side ends of the trunnions of both closure parts and supports for the bearing spindles being provided in the valve casing.

3. A non-return valve according to claim 2, wherein the supports are constituted by two brackets held on the valve casing on the outflow side behind the closure parts and extending longitudinally over and beyond the trunnions, said brackets having at their free ends transverse arms which project between the facing ends of the trunnions adjacent to the closure parts and hold the bearing spindles.

4. A non-return valve according to claim 3, wherein the brackets constitute the webs of two U-shaped frames fixed in each case by one leg to a wall of the valve casing and have bearing points for the trunnions whilst the other legs form said transverse arms and hold the bearing spindles.

5. A non-return valve according to claim 4, wherein the said one legs of the U-shaped frames rest on respective shoulders formed on the valve casing.

6. A non-return valve according to claim 4 or claim 5, wherein each U-shaped frame has, in the casing-side leg between the bearing point for the trunnions and its web, a locating hole for a respective fixing screw.

7. A non-return valve according to any one of claims 4 to 6, wherein the said one leg of each Ushaped frame has two locating holes for the trunnions.

8. A non-return valve according to any one of claims 4 to 6, wherein the valve casing is provided with a supporting shoulderforthe trunnions and the said one legs of the U-shaped frames have, in each case, two locating slots for the trunnions which are open towards the supporting shoulder and which serve as said bearing points.

9. A non-return valve according to any one of claims 4 to 8, wherein spacing plates are arranged between the said one legs of the U-shaped frames and the wall of the valve casing.

10. A non-return valve according to any one of claims 2 to 8, wherein at their one free ends, the bearing spindles are fixed to one of the supports.

11. A non-return valve according to claim 10, wherein the bearing spindles are axially displaceably mounted on the other support.

12. A non-return valve substantially as described herein with reference to the drawings.