GB2069104A - Solenoid valve - Google Patents

Abstract

A three-way solenoid operated valve has a coil 10, a core 12 and an axially movable armature 18. One end of the armature engages a stem 52 which passes through the core and actuates a venting valve mechanism 48, 56. The other end of the armature actuates a main valve mechanism 26, 32. The armature is normally biassed by a spring 54 to close the main valve mechanism 26, 32. In this position a chamber 28 on the outlet side of the main valve is vented to an outlet 66 via passageways 36, 38, 40, 42 and 44. When the solenoid coil 10 is actuated the armature 18 opens the valve mechanism 26, 32 and closes the valve mechanism 48, 56. Fluid may then flow from an inlet 34 through the valve orifice 32 and through passageways 84, 74, 72 and 76 to outlet 30. <IMAGE>

Description

SPECIFICATION Solenoid valve This invention relates to a solenoid operated valve. It is particularly applicable to a three-way solenoid valve, e.g. one which has an inlet and two outlets, one of which may be a venting outlet.

Conventionally, such valves have a solenoid coil, and in the coil there is a core of magnetic material.

An armature is movable in the longitudinal direction of the coil and generally partly within it, towards and away from the core. When the coil is energised, the armature is attracted to the core, and it is spring biassed so as to move away from the core when the coil is de-energised. At the end furthest from the coil and core, the armature carries a seat for the main valve orifice. This seat is urged against the main orifice (which leads to one of the outlets) by the spring when the coil is de-energised. In this conventional valve, the opposite end of the armature, closest to the core and within the coil, also carries a seat which closes a venting valve orifice leading to the other outlet when the coil is energised.Thus, the venting orifice is provided in the face of the core which is adjacent the inner end of the armature, and the venting outlet is a passage which leads through the core.

One problem with this arrangement arises from the fact that there must be an air gap between the armature and the core because the venting valve seat is necessarily of a resilient nature and must be compressed to make a seating with the venting orifice, and because allowance must be made for wear on the seat when it hits the core around the orifice with the full force caused by the magnetic attraction between the core and the armature when the coil is energised. This air gap affects the performance of the solenoid valve, particularly in the case of a low demand valve where the gap will be decreased by wear only slowly, because the effective travel of the armature and the attraction of the armature to the core are both decreased.

According to the present invention we provide a solenoid operated valve having a solenoid coil, a core for the coil, of magnetic material, and an armature of magnetic material which is arranged to move towards the core when the coil is energised and which is otherwise biassed away from the core, the movement of the armature towards the core being transmitted past the core by a stem to actuate a valve mechanism disposed on the side of the core remote from the armature.

Preferably the solenoid valve is of the threeway type pnd has a further valve mechanism disposed at the end of the armature remote from the core, one valve mechanism being open when the other is closed.

The valve on the remote side of the core from the armature may comprise a valve seat which is carried by the stem and which closes a valve orifice when the armature is moved towards the core. The orifice may be adjustable towards and away from the seat.

A solenoid valve according to the invention will now be described by way of example with reference to the accompanying drawing, which is a cross-section of the valve.

Referring to the drawing, the solenoid valve comprises a solenoid coil 10 which has a core 1 2 of magnetic material. The core 12 extends at 14 to form a top cover for the coil 10. This forms part of a magnetic circuit which leads around the outside of the solenoid coil 10 (not shown) to a bottom cover 1 6. An armature 1 8 of magnetic material is slidable in the bore 20 of the coil 10 and in a bore 22 in the bottom cover 16. At its bottom end, the armature 1 8 carries a main valve seat 26 of resiliently compressible material. This is located in a chambers 28 below the armature 18, which communicates with outlet passages 84, 74, 72, 76, 30. Normally, the valve seat 26 closes a main valve orifice 32 which leads from a main inlet passage 34 for the valve.The drilled outlet passages 72 are in a bottom screwed insert 80 and allow the position of the orifice 32 with respect to seat 26 to be turned and adjusted on assembly. "0" rings 78 prevent insert 80 turning in use and seal off the inlet passage 34 from 74, 76, defining an annular passage from the inlet 34 to the orifice 32. However, when the coil 10 is energised the armature 1 8 is attracted to the core 12, lifting the seat 26 from the orifice 32, so that fluid can flow from the inlet 34 to the outlet 30.

When the seat 26 is closing the orifice 32, the chamber 28 is vented via a groove 36 in the side of the armature 1 8. This leads to the air gap 38 which is present between the core 12 and armature 18 when the main valve is closed, through passages 40, 42, 44 through the core 12 and top cover 14 to a chamber 46 in the top cover. In the chamber 46, there is a venting valve seat 48 carried on a head 50 at the top end of a stem 52. The stem 52 extends through the passage 44 and is received slidably in an axial bore in the core 12, its lower end being in contact with the armature 1 8. This contact is maintained by a spring 54 acting on the head 50. The spring 54 also serves, through the stem 52, to bias the armature 18 downwardly so that the seat 26 is biassed to close the orifice 32 except when the coil 10 is energised.

Opposing the seat 48 is a venting valve orifice 56 in a threaded insert 58. The orifice 56 is normally open, but when the coil 10 is energised and the armature 1 8 is attracted towards the coil 12 the venting valve seat 48 bears against the venting valve orifice 56. The orifice 56 leads to an axial passage 60 in the insert 58, which in turn leads to a chamber 62 provided by an inverted cupshaped cap 64 which is grub screw located onto the solenoid valve. The cap 64 has an outlet passage 66 leading from the chamber 62 which, when the coil 10 is not energised, provides the venting for the valve.

The top of the screwed insert 58 is provided with a pair of drilled holes 68, and by simply removing the grub screw located cap 64 the position of the orifice 56 with respect to the seat 48 can be adjusted by screwing in the insert 58. It is particularly advantageous that apart from the removal of the cap 64 no further dismantling of the solenoid valve is required to effect this adjustment. The adjustment is performed while the coil 10 is energised, so that the armature 18 is in contact with the core 12, and the insert 58 is adjusted until a tight seating is obtained between the orifice 56 and seat 48. An "0" ring 82 prevents insert 58 turning in use and seals off chamber 62 from 46.

Apart from this ease of adjustment, further advantages stem from the fact that the seat 48 and orifice 56 are remote from the core and armature. For example, there is no need for any air gap to be left when the armature 18 is brought towards the core 12, as would be the case if the armature carried the seat 48 and the core of the orifice 56. The absence of this air gap means that the attraction between the armature and the core is maximised, giving a more positive action to the valve, or alternatively permitting the use of a less powerful solenoid. The distance travelled by the armature is also maximised so as to give a larger degree of opening of the orifices 32 and 56. (In practice, a very thin brass shim is provided on the upper face 70 of the armature, so as to provide a very small gap which makes it easier to disengage the armature and core when the coil 10 is deenergised.) A further advantage is that as long as the insert 58 is correctly adjusted the wear on the seat 48 is reduced. This is because the seat 48 is only compressed by the amount necessary to form a seal. Further compression, which in a conventional valve would be caused by the impact of the seat 48 on the orifice 56 as the armature is attracted towards the core, and which would cause excessive wear, is prevented because the armature 1 8 physically meets the core 12.

Claims (11)

1. A solenoid operated valve having a solenoid coil, a core for the coil, of magnetic material, and an armature of magnetic material which is arranged to move towards the core when the coil is energised and which is otherwise biassed away from the core, the movement of the armature towards the core being transmitted past the core by a stem to actuate a valve mechanism disposed on the side of the core remote from the armature.

2. A valve as claimed in claim 1 in which the valve mechanism comprises a valve seat and a valve orifice, the spacing between which is adjustable.

3. A valve as claimed in claim 1, in which the valve mechanism comprises a valve seat carried by the stem which is disposed to close a valve orifice when the armature is moved towards the core.

4. A valve as claimed in claim 3 in which the valve orifice is adjustable towards and away from the seat.

5. A valve as claimed in claim 4 in which the valve orifice is provided in a threaded insert and the adjustment is provided by screwing the insert in or out.

6. A valve as claimed in any preceding claim in which a further valve mechanism is disposed at the end of the armature remote from the core, one valve mechanism being open when the other is closed.

7. A valve as claimed in claim 6 in which the said further valve mechanism comprises a valve seat carried on the end of the armature remote from the core, and an opposing vaive orifice.

8. A valve as claimed in claim 7 wherein the valve orifice is adjustable towards and away from the seat.

9. A valve as claimed in any one of claims 6 to 8 which is a three-way valve, in which the further valve mechanism is the main valve mechanism thereof and the first-mentioned valve mechanism is a venting mechanism, there being a venting passage or passages leading from the outlet side of the main valve mechanism to the venting valve mechanism.

10. A valve as claimed in claim 9, in which the venting passage comprises a longitudinal groove formed in the side wall of the armature.

11. A solenoid operated valve, substantially as described herein with reference to the accompanying drawing.