GB2068509A - Suction valves - Google Patents

Abstract

A suction valve for a pressure pump includes an annular valve seat (4) defining a flow path and a closure member with an annular seating surface arranged to cooperate with that of the valve seat part. The seating surface (11) of the closure member (7) is formed at its periphery as a part- spherical surface and the valve seat (4) is formed as a part of a conical surface or has a convex curvature considered in cross-section, Fig. 3, (not shown). <IMAGE>

Description

SPECIFICATION Valves The invention relates to a suction valve according to the preamble of patent claim 1.

A suction valve is conventionally controlled in a hydraulic pump automatically by the suction pressure. In a known construction a sleeve-like insert is provided, which surrounds a path for the pressure medium, and defines an annular ring shaped plane valve seat which serves for the support of a plane surface side of the disc shape closing body. The closing body is loaded by a spring, which presses it onto the valve seat, when no appreciable pressure is generated in the passage. In a still new suction valve of this kind in spite of the fine machining of the cooperating surfaces there remains a roughness, which is only lost with increasing period of use. The cooperating surfaces so to speak beat each other smooth. If the suction valve is then closed, there arises, however, during light loading of the pump a substantial audible unacceptable noise.This metallic noise disappears again, as soon as the pump is working under load. This no-load noise simulates a mechanical defect in the pump, as a result of which the pump user is made uncertain.

He replaces the suction valve, although this remains fully operational. If he, on the other hand, after a suitable construction on the part of the manufacturer of the pump continues to operate it and ignores the noise generation the danger arises, that he overlooks the initiation of an actual mechanical defect in the workings of the pump.

The invention is based on the problem of improving a suction valve of the hereinbefore mentioned kind so that it operates without noise throughout the whole of its operational life.

The stated problem is solved in accordance with the invention by the features set forth in the characterising clause of patent claim 1.

By means of this construction a circular line shaped contact line is produced between the closing body and the valve seat, which remains maintained even after a long operational period and running of a suction valve. Even if as a result of the turbulent circulatory flow by the pressure medium the closing body is from time to time caused to seat on the valve seat in a tilted condition, there remains a circular line shaped contact zone, since the seat surface part is a sphere surface which always contacts the valve seat on the same circle diameter. Most importantly the suction valve in accordance with the invention gives rise to no no-load noise. With the known suction valves after long term use the valve seat impresses itself in the seating surface of the closing body.This disadvantage is likewise overcome by the construction in accordance with the invention, since the cooperating surfaces always enter into contact with one another flush and no edges are provided, which can sink into or impact the groove action. A mechanical wear of the cooperating surfaces naturally cannot be excluded, however this wear is so balanced with regard to the valve seat and the seating surface, that no groove formation, ribs or such uneven features arise.

A preferred construction of the invention is apparent from claim 2. With such cone angles of the valve seat there is produced in the closure position a particularly good sealing action.

A further, preferred construction of the invention is set forth in claim 3. With this feature it is ensured that even with a tilted closure body a satisfactory sealing action takes place.

A further, preferred embodiment of the invention is set forth in claim 4. This width ratio ensures that even with extreme tilting of the closure body no sharp edges can enter into contact with one another and that furthermore any eventually produced wear is distributed over an optimum large surface.

A further, preferred embodiment by way of example of the invention is set forth in claim 5.

The closure body is, in this manner given particular design strength but is nevertheless light so that the valve operates even with high operating speeds satisfactorily and does not impact the valve seat. A disc-like closure body with spherical seating surfaces is subject to particularly satisfactory flow conditions.

A further, preferred embodiment of the invention is set forth in claim 6. With this constructional feature a favourably large seating surface for the closure body is provided.

Nevertheless its overall size and thus its weight is small. The cup-shape of the underside of the closure body leads additionally to the fact that the surrounding pressure medium after initial raising of the closure body of the suction valve can maintain it completely open easily and quickly.

A further, preferred embodiment of a suction valve, in which there is provided a surrounding spacer spaced from the valve seat, which supports the spring loading the closure body, will be apparent from the claim 7. This arrangement leads to easy guidance during movement of the closure body, which under certain operational conditions is of considerable value. Moreover, the projection or extension gives rise to a balanced force action by the valve spring.

A further, preferred embodiment of the invention is set forth in claim 8. This constructional feature improves the through flow characteristics of the suction valve. Moreover with all the embodiments of the invention by the construction of the seating surface and of the valve seat and flow characteristics in the suction valve are substantially improved. With conventional valves with disc-shaped closing bodies during initial opening of the valve and also in the completely open condition substantial turbulences are generated at the sharp edges of the valve seat and with flow around the closure body, which lead not only to energylosses but also additional closure initiated loads on the valve elements (cavitation).

Finally, a further important concept of the invention is set forth in claim 9.

The suction valve in accordance with the invention can be converted without substantial modifications to act as a pressure valve. This simplifies and renders less expensive the manufacture as well as the assembly of the valves of the pumps, since at least the same closure bodies for both valves can be used.

Embodiments of the invention will be hereinafter explained with reference to the drawing. There is shown Figure 1 a transverse section through a suction valve, in the right hand in the closed position, in the left hand in the open position, Figure 2 a transverse section through a pressure valve, and Figure 3 a detail from a further modified embodiment.

A suction valve 1 is arranged in a housing wall 2 of a not further illustrated hydraulic pump. A sleeve-shaped body 3 surrounds a flow path for a pressure medium. The body 3 is broadened out at a part of its longitudinal extent tQ conical shape (zone 6) and ends in the inside of the valve 1 with a valve seat 4. The valve seat 4 is annular and part of a surface of a cone, of which the point of the cone lies in the flow path 5.

The valve seat 4 is provided on a closure body 7 with mushroom-shape configuration, which has a plane surface 8 and a parallel surface 9. The surface 8 is surrounded by a circumferential and upstanding rim 10. The closure body 7 has its seating surface 11 at the outer periphery of the disc-shaped part of the mushroom, which is part of a spherical surface, of which the centre point lies in the middle axis of the cone of the conical surface of the valve seat 4. The breadth B of the seating surface 11 is approximately three to four times as wide as the breadth b of the valve seat 4.

The generatrix of the valve seat 4 is tangential in the closure position of the seating surface 11 in the right hand half of the indicated Figure 1, so that a circle-line shaped contact zone is provided between two parts, in which the flow path is shut off.

The body 3 is inserted in a stepped bore 12 of the housing wall 2 and by packing in the zone 18 is secured in place. It simultaneously secures a flange 17 of a cage 14 in the bore 12, which serves for the support of a valve spring 1 6, which presses against the surface 9 of the closure body 7 and biases this into its closure position.

On the surface 9 a pin-like projection 1 3 is arranged, whcih projects with radial play-through a guide opening 1 5 of the cage 14, so that a loose guidance of the closure body is effected.

In the left half of Figure 1 valve 1 is illustrated in its open position, in which the pressure in the flow path 5 has raised the closure body 7 so that the seating surface 11 is spaced from the valve seat 4, and the pressure medium can further flow into the bore 1 2. For this purpose the cage is provided with interruptions, which are not illustrated in the drawing.

In the contact zone between the closure body and the valve seat there can also be a circular arc line, if the closure body 7 is slightly tilted in relation to the illustrated position.

A pressure valve 20 is illustrated in crosssection in Figure 2, which is basically of the same construction as the hereinbefore described suctioh valve. The right-hand half of Figure 2 indicates the closure position and the left-hand hålf of the open position of the pressure valve. A sleeve-shaped body 21 is secured in the housing wall 2 by packing and is widened out in the zone 22 and forms a valve seat 23, which is part of a conical surface, of which the cone angle alpha amounts to 900 or less. A closure body 24 seats on the valve seat 23 with its seating surface 25 disposed at the periphery, which is part of a sphere. The closure body 24 has a pin-like projection 26, which engages in an opening 28 of a cage 27, so that the closure body is loosely guided by the cage 27.

The closure spring 16 loads the closure body in the direction towards the valve seat 23. The cage 27 is located by pressing in the housing bore. In the left hand half of Figure 2 it is to be seen how the closure body 24 is raised by pressure in the flow path 30 and a flow permitted through the valve seat 23.

In Figure 3 there is shown a sleeve-shaped body 31 in section, which can be used in place of the body 21 or 3 of figures land 2; and has a valve seat 34, which is of convex curvature. The generatrix of the valve seat 34 is for example a circular arc section with the radius 36 and the mid-point at 35. The body 31 again limits a pressure medium flow path 23 and is broadened in a longitudinal zone 33 of conical shape.

Claims (9)

1. Suction valve for a pressure medium pump, in particular for a high pressure hydraulic pump, with an annular valve seat surrounding a flow path, to which in the closed position a spring loaded, disc-like closing body with an annular seating surface is applied, which can be raised by the pressure of the pressure medium in the flow path automatically from the valve seat, characterised in this that the seat surface (1 1, 25) of the closure body (24, 7) is formed at its periphery as a part of a spherical surface and the valve seat (4, 23, 34) is formed as a part of a conical surface or is curved convexly in crosssection.

2. Suction valve according to claim 1 characterised in this that the cone angle (cur) of the valve seat (4, 23) amounts to 900 or less.

3. Suction valve according to one of claims 1 or 2, characterised in this that the imaginary centre point of the spherical surface lies on the middle axis of the conical surface.

4. Suction valve according to one of claims 1 to 3, characterised in this that the width (B) of the seating surface (11, 25) corresponds to approximately three times to four times the width (b) of the valve seat (4, 23, 34).

5. Suction valve according to one of claims 1 to 4, characterised in this that the closure body (7) has a disc-like configuration with surfaces (8, 9) parallel to one another.

6. Suction valve according to claim 5, characterised in this that at least the surface (8) of the closure body (7) is surrounded by a peripheral rim (10) of which the outer periphery is of spherical configuration.

7. Suction valve according to one of claims 1 to 6, in which a cage surrounds at a distance the valve seat, which supports the spring loading the closure body, characterised in this that the closure body (7) is made of mushroom shape and engages freely in a guide opening (1 5) in the cage (14) with a projection (13) arranged on the surface (9) opposite to the through flow path (5).

8. Suction valve according to one of claims 1 to 7, characterised in this that the through flow path (5, 30) is broadened (6, 22, 33) over a part of its longitudinal extent over a part of its valve seat (4, 23, 34) conically.

9. Suction valve according to claims 1 to 8, characterised by its use as a pressure valve in a high pressure hydraulic pump, a reversed through flow direction being substituted.

1 0. A suction valve substantially hereinbefore described with reference to the accompanying drawing.