GB2258288A

GB2258288A - Control valve

Info

Publication number: GB2258288A
Application number: GB9215259A
Authority: GB
Inventors: Helmut Goettling; Rudolf Moeller; Gerhard Scharnowski
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1991-07-31
Filing date: 1992-07-17
Publication date: 1993-02-03
Also published as: DE4125817C2; ITMI921525A1; DE4125817A1; FR2679976A1; ITMI921525A0; GB9215259D0; IT1254983B

Description

2 2 -,,,2 j 1 CONTROL VALVE Constantly operating valves (directional

control-, pressureand flow valves), whose hydraulic output value is proportional to the electrical input signal and which are generally actuated by a proportional magnet, are known. A pilot-controlledi multi-channel valve of this kind is described in German Published Application 38 42 633 and comprises a plurality of pressure medium chambers arranged in series. The stem and the valve piston are guided through 0-rings. The adjustment of the two parts is correspondingly difficult due to the effects of friction. Furthermore, the seat diameters must be designed to be overlarge for the provision of the sealing rings and the structurally influenced flow cross- sections.

To reduce the adjusting energy which must be expended, friction forces must be substantially avoided. Pressure- and closing forces are to be minimised. Therefore the stems which are required should also not be conducted through the seats. It should also be ensured that the valve- and magnet strokes are adapted to one another.

The object of the invention is to address the problem of providing a directional control valve which can be operated with the least possible energy.

According to the present invention, there is provided a directional control valve, in particular a proportional valve for a pneumatic medium, comprising a valve housing and an operating member guided therein, an electromagnet which is positioned in sealing fashion on the valve housing and the armature of which actuates the operating member, and comprising media terminals for operating-, pressure-, and ventilating lines, wherein the operating member is movable between three positions in a central bore of the valve housing, wherein first lever ends of axially supported, lever-like seal carriers abut against said operating member, the seal carriers being pivotably mounted at their other, second lever end in the valve housing, and biased resiliently into engagement with the operating 2 element, and in a predeterminable lever length ratio bear a sealing element, and that a pressure chamber is formed within the valve housing, in which chamber a respective seal seat associated with a media terminal is assigned to each sealing element.

The advantages attained by the invention consist, in particular, in that only two very light, or in dependence upon the valve, even only one single U-shaped seal carrier are/is mounted in the valve housing in such manner that when the stem is in the central position the seal carriers can be pressed against the existing sealing seats by the compression springs, which requires only minimal energy. At the same time such a valve can be produced cost-favourably and requires fewer parts than previously. For different strokes, stroke adaptation can be carried out via the lever length ratio.

In accordance with further features of the invention it is advantageous that the lever-like seal carriers are formed from sheet metal and include bent, angled portions which abut against an end face of the large shaft member formed on the valve stem. Commencing from the aforementioned central position, when the magnet armature is retracted the governing spring urges the lever-like seal carrier away from the seal seat and thereby releases the flow cross-section.

An improvement of the invention provides that at its first lever end the lever-like seal carrier is guided between projections which are formed on a surface of the pressure chamber in the valve housing. The lever-like seal carrier is thus always moved at right angles to the sealing plane.

Other features provide that the respective bent, angled portions of two lever-like sealing bodies abut against oppositely disposed end faces of the shaft member formed on the valve stem. In this design a 3/3-way valve is formed.

Another advantageous embodiment of the invention provides that media channels, the outputs of which form the media terminals, extend in a wall cross-section of the valve housing adjacent to the pressure chamber,. Advantageously this produces short flow paths within the valve.

3 An improvement of the invention provides that the valve housing is substantially formed by an inner hub, an outer rim and the wall crosssection which accommodates the media channels. Depending upon the size of the valve, a substantial amount of material can thus be saved in comparison to known valve housings.

A further improvement of the invention consists in that for the compression springs which subject the lever-like seal carriers to spring force, a respective receiving trough is formed in a cover housing and in the valve housing cover, and a guide shoulder is formed on the lever-like seal carrier. These two measures ensure a secure mounting of the compression springs.

The range of application of the invention is extended in that by means of two seal carriers which are arranged so as to be axially offset and to extend radially towards opposite sides a 3/3-way valve is formed, and by omitting one of the two seal carriers a 2/2-way valve is formed.

An exemplary embodiment of the invention is illustrated in the drawings and will be described in detail in the following, wherein:

Figure 1 is an axial cross-section through the directional control valve; Figure 2 is a section on the line II-II of Figure 1; Figures 3 and 4 illustrate a radial cam-type rotary drive; and Figures 5 and 6 illustrate an axial cam-type rotary drive.

The directional control valve, designed in particular as a proportional valve for a pneumatic medium, comprises a valve housing 1 and a valve stem 2 guided therein for linear reciprocating movement. An electromagnet 3 is positioned on and attached to the valve housing 1 via a sealing ring la. Via an applied adapting sleeve 4a, the armature 4 of said electromagnet 3 actuates the valve stem 2 which is supported by means of a governing spring 6, facing away from the electromagnet 3. in a valve housing cover 5 positioned in sealing fashion (by means of an 0-ring 5a). Media terminals 7, 8, 9 for operating-, pressure- and ventilating lines are also provided.

4 The valve stem 2 guided on a central axis 11 comprises a central operating member 12 with a larger diameter 13 than the adjacent portions, and the larger diameter 13 is mounted in sliding fashion in a central bore 14 of the valve housing 1. Respective first ends 15 of leverlike sealing carriers 16 abut against the axially facing end surfaces of the central operating member 12 with the larger diameter 13, and second ends 17 of said seal carriers 16 are pivotably mounted in the valve housing 1. A respective compression spring 18 supports each of the second ends 17 of carriers 16 against a cover housing 19, or against the valve housing cover 5. The lever-like seal carrier 16 is provided in a predeterminable lever length ratio with a sealing element 20 which is of conical formation and the cone 20a of which is attached in a corresponding recess of the seal carrier 16.

For the seal carriers 16, a pressure chamber 21 is formed between the cover housing 19 and valve housing 1, and between the valve housing cover 5 and the valve housing 1. Each sealing element 20 is assigned a seal seat 22 for one of the media terminals 7 and 9. Media terminal 8 opens directly into the chamber 21.

The lever-like seal carriers 16 are expediently formed from sheet metal and have bent, angled portions 23 which each abut against an end face 24 of the central operating member 12 of the valve stem 2. At its second lever end 17 the lever-like seal carrier 16 is guided between projections 25 which are formed on a surface 26 of the pressure chamber 21 in the valve housing 1. As illustrated, the respective angled portions 23 of two lever-like seal carriers 16 are positioned against oppositely disposed end faces 24 of the central operating member 12 formed on the valve stem 2. In the event of an axial displacement of the valve stem 2, then depending upon the direction of axial movement one or the other of the seal carriers 16 is pivoted about its second end 17 so that its associated sealing element 20 is lifted from the seal seat 22 and the corresponding media terminal 7 or 9 is opened. Depending upon the position of the media terminals 7 and 9, the directional control valve may be open or closed in the stress-free state.

The media channels 7, 8 and 9, the outputs 28 of which form the media terminals, extend in a wall cross-section 27 of the valve housing 1 adjacent to the pressure chamber 21. Such an arrangement of the media channels 7, 8 and 9 is possible in that the valve housing 1 is substantially composed of an inner hub 29, an outer rim 30 and a wall cross-section 27 which accommodates the media channels 7 to 9.

For the compression springs 18 which subject the lever-like seal carriers 16 to spring force, a respective receiving recess 32 is formed in the cover housing 19 and in the valve housing cover 5 and a guide shoulder 33 is formed on the lever-like seal carrier 16. As illustrated, in the exemplary embodiment the guide shoulder 33 is conical to allow the centring and guidance of the compression spring 18.

By means of two seal carriers 16 which are arranged so as to be axially offset and so as to extend radially towards opposite sides, a 3/3-way valve can be formed and by omitting one of the two seal carriers 16 a 2/2way valve can be formed.

The directional control valve can be attached to any machine or device by means of fixing bores 34.

The directional control valve is expediently used as a constant pilot valve.

In Figures 3 and 4 the directional control valve is adapted for operation by a rotary actuator; the valve components which have been used here being substantially identical to those shown in Figures 1 and 2 with the exception of the valve stem 13 and electromagnet. In place of the electromagnet 3, which was in the form of a lifting magnet in Figure 1, here a swivel drive 35 with a sealing element 36 has been provided so that the drive output of the actuator is a rotary shaft 37. Rotation of cam element 121 clockwise as seen in the Figure causes the heel of cam 121 to lift the upper seal carrier 16, opening media port 7 to communicate with port 8. Rotation in the opposite sense depresses lower seal carrier 16, opening media port 9 to communicate with port 8.

6 Figures 4 and 5 illustrate a similar construction for a rotary drive, the individual parts of which likewise substantially correspond to the design illustrated in Figures 1 and 2. The operating member 1211 additionally comprises axial cam surfaces 381 and 3811. Advantageously a double bearing 39 is provided in the valve housing 1 for the accommodation of axial- and radial forces. Rotation of operating member 1211 clockwise as seen in Figure 6 causes lower seal carrier 16 to be depressed by the engagement of its end 23 with cam surface 381. opening communication between ports 9 and 8. Rotation in the opposite sense opens port 7 to communicate with port 8 by lifting upper seal carrier 16 due to the engagement of is end 23 with cam surface 3811.

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Claims

1. A directional control valve, in particular a proportional valve for a pneumatic medium, comprising a valve housing and an operating member guided therein, an electromagnet which is positioned in sealing fashion on the valve housing and the armature of which actuates the operating member, and comprising media terminals for operating-, pressure-, and ventilating lines, wherein the operating member is movable between three positions in a central bore of the valve housing, wherein first lever ends of axially supported, lever-like seal carriers abut against said operating member, the seal carriers being pivotably mounted at their other, second lever end in the valve housing. and biased resiliently into engagement with the operating member, and in a predeterminable lever length ratio bear a sealing element. and that a pressure chamber is formed within the valve housing, in which chamber a respective seal seat associated with a media terminal is assigned to each sealing element.

2. A directional control valve as claimed in Claim 1, wherein the lever-like seal carriers are formed from sheet metal and by means of bent, angled portions abut against respective axial end faces of a central enlarged operating member, the operating member being axially movable between a central, neutral position and operating positions displaced axially in opposite senses from the neutral position.

3. A valve according to Claim 1, wherein the operating member is a rotary cam movable between three angular positions. a central neutral position and operative positions spaced angularly on opposite sides of the neutral position.

4. A directional control valve as claimed in Claims 1 to 3, wherein the first lever end of the lever-like seal carrier is guided between projections which are formed on a surface of the pressure chamber in the valve housing.

5. A directional control valve as claimed in Claims 1 to 4, wherein the respective bent, angled portions of two lever-like seal carriers abut against oppositely disposed faces of the operating member.

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6. A directional control valve as claimed in any preceding Claim, wherein media channels, the outputs of which form the media terminals, extend in a wall cross-section of the valve housing adjacent to the pressure chamber.

7. A directional control valve as claimed in any preceding Claim, wherein the valve housing substantially comprises an inner hub, an outer rim and the wall cross-section which accommodates the media channels.

8. A valve housing as claimed in any preceding Claim, wherein the resilient bias of the seal carriers is achieved by compression springs which subject the lever-like seal carriers to spring force, a respective receiving trough being formed in a cover housing and in the valve housing cover, and a guide shoulder being formed on the lever-like seal carrier, to receive the ends of the springs.

9. A directional control valve as claimed in any preceding Claim, wherein two seal carriers are arranged so as to be axially offset and to extend radially towards opposite sides.

10. A valve according to Claim 9, wherein by the omission of one of the two seal carriers a 2/2-way valve is formed.

11. A valve substantially as herein described with reference to Figures 1 and 2, Figures 3 and 4, or Figures 5 and 6.