GB2204381A

GB2204381A - Solenoids

Info

Publication number: GB2204381A
Application number: GB08709611A
Authority: GB
Inventors: Michael Clift
Original assignee: Teddington Controls Ltd
Current assignee: Teddington Controls Ltd
Priority date: 1987-04-23
Filing date: 1987-04-23
Publication date: 1988-11-09
Also published as: GB8709611D0

Abstract

The solenoid-operated valve comprises a coil (25) operating an armature (26) carrying a shaft (30). A body (31) has a cavity (34) which houses the coil and armature, and has an opening (32) through which the shaft passes. A valve head (20) is carried on the free end of the shaft. The relative diameters of the cavity (34) and the armature are selected so that the armature can close the valve in the tilted position shown if the shaft is improperly aligned with a valve seat (not shown). The upper and lower edges (36, 37) of the armature contact opposite sides of the cavity (34). No contact between shaft (30) and the periphery of opening (32) takes place, the diameter of the opening being enlarged to ensure this. The maximum angle of tilt allowed for is 1 DEG 4 min , equivalent to 1.3 mm tip displacement at the valve head. <IMAGE>

Description

SOLENOIDS.

This invention relates to solenoid-operated valves of the kind in which a valve head co-operates with a valve seat.

The invention provides a solenoid-operated valve in which an armature moves in a cavity in a coaxial coil, the armature carrying a shaft on which a valve head is mounted, the shaft leaving said cavity through an opening, the relative diameters of the cavity and armature, shaft and openings being such that the armature may tilt until its upper and lower edges contact the cavity walls without the shaft contacting the walls of the opening.

Preferably the angle of tilt so achieved is about 1041. The valve head may be tapered so as to co-operate with a tapered valve seat whereby misalignment between the valve head and seat is accommodated by the shaft and armature being urged to take up said tilt. The armature may carry the shaft at one end and at its other end have a conical opening which co-operates with a tapered stop whereby the armature is restored to a central position when it is retracted.

A specific embodiment of the invention is shown in the accompanying drawings, in which: Figure 1 is a side section through a composite gas control, and Figure 2 is a detail of Figure 1 showing a solenoid-operated valve in section.

Referring first to Figure 1, a composite gas control (11) comprises two independently-operated valves (12, 13) arranged in gas series. One valve (12) is operated by a thermostatic sealed system (14) of which only part is shown, while the other valve (13) is operated by a solenoid (15).

When both valves are open, a gas path is completed from inlet (16) to outlet (17). Such a composite control may be used in a gas cooker in which a timer operates the solenoid and the oven temperature operates the thermostat, so that timed cooking operations can be made.

The solenoid-operated valve (13) has a hardened rubber tapered head (20) which seats in a chamfered seat (21). The valve (13) is mounted in the body (22) of the control (11) by means of a threaded portion (23) which engages a similarly threaded opening in the body (22). It will be seen that any misalignment of the threaded opening and seat (21) will mean that the head (20) is imperfectly aligned with the seat.

As seen in Figure 2, the solenoid-operated valve comprises a coil (25) which when energized operates on an armature (26) in the sense to draw the armature up and withdraw the valve head (20) from the seat (21).

Spring (27) opposes this movement. tapered stop (28) engages in a tapered opening (29) in the end of the armature as the opening movement takes place to centre the armature and locate it in its open position.

A shaft (30) of smaller diameter than the armature is secured to it and to the valve head (20). The solenoid is mounted in a body (31) having at one end the threaded portion (23) and concentric with portion (23) an opening (32) through which the shaft passes. Internally of the coil (25) there is a cylindrical cavity (34) in which the armature works, cavity (34) having a larger diameter than opening (32).

The relative diameters of the cavity (34) and the armature are selected so that the armature when in the closed position shdwn in Figure 2 can take up a tilted position. This is shown to an exaggerated degree in Figure 2, the upper edge (36) of the armature contacting the cavity wall and the lower edge (37) of the armature contacting the opposite side of the cavity wall. This degree of tilting takes place without any contact between the shaft (30) and opening (32), the diameter (32) being enlarged to ensure this.

The maximum angle of tilt A allowed from the mean position is 1041, an increase of some 30% on more usual arrangements. This is equivalent to 1.3 mm tip displacement when the shaft is projecting the same amount as when installed in the body.

h'hen the tapered valve head (20) approaches seat (21) to close the valve and the seat is not fully aligned with the head, the tapered edge of the head engages the similar chamfer of the seat (21). The shaft and armature (26) then tilt until the valve head is guided into alignment with the seat (21) and the valve closes.

When the valve opens, the armature is drawn back, the stop (28) engages in te armature, and the armature is guided back into a central position in the cavity (34). Electrical leads (38) supply fully rectified electrical power to the solenoid so that there is little or no tendency to chatter.

It is of importance that shaft (30) does not contact the sides of opening (32) because remanent magnetism would hold the movement up, slowing operation of the valve. Thus the relationships between the diameters of cavity (34), armature (26), opening (32) and shaft (30) are carefully calculated to allow the degree of tilting to cause the armature to contact the cavity without the shaft contacting the opening (32).

Claims

CLAIMS:

1. A solenoid-operated valve in which an armature moves in a cavity in a coaxial coil, the armature carrying a shaft on which a valve head is mounted, the shaft leaving said cavity through an opening, the relative diameters of the cavity and armature, shaft and opening being such that the armature may tilt until its upper and lower edges contact the cavity walls without the shaft contacting the periphery of the opening.

2. A valve as claimed in claim 1, wherein the angle of tilt of the armature at which said upper and lower edges contact the cavity walls is Gp to 104

3. A valve as claimed in claim 1 or claim 2, wherein the valve head is tapered so as to be able to co-operate with a tapered valve seat w--êrebv misalisnment between the valve head and seat may be accommodated by the shaft and armature being urged to take up a tilted position.

4. A valve as claimed in any of claims 1 to 3, wherein the armature rries the shaft at one end and at its other end has a conical opening we cm engages with a stationary tapered stop when the armature is retracted, whereby the armature is restored to a central until csition

5. A valve as claimed in any of claims 1 to 4, having a housing in which the coil is located, said housing providing said opening and concentric with said opening a threaded portion whereby the valve may be rrounted.

6. A solenoid-operated valve substantially as described hereinbefore with reference to Figure 2 of the accompanying drawings.

7. A solenoid-operated valve as claimed in any of claims 1 to 6, mounted in a composite gas control body which houses a valve seat for the valve.

8. A solenoid-operated valve as claimed in claim 7 and substantially as described hereinbefore with reference to Figure 1 of the accompanying drawings.