GB2486225A - Stackable solenoid - Google Patents

Abstract

An electro-mechanical solenoid actuator 5, 6, suitable for a stacked configuration, is arranged to provide a multiple redundancy function. The solenoid actuator 5, 6 may include an external housing enclosing a wire coil surrounding a moveable metallic core 3a, 3b. The housing and core 3a, 3b are designed so that when two or more solenoids 5, 6 are held in contact with each other, movement of one core 3a will be transferred into the core 3b of the other solenoid 6 such that the said cores 3a, 3b move in unison. The external housing of a solenoid may be arranged to have surfaces which correspond with those of another like solenoid, such that solenoids can be readily arranged into an appropriate stacked configuration.

Description

Stackable Solenoid

Field of the invention

The invention relates to electrically operated solenoids. In particular, the invenUon relates to, but is not limited to, solenoids used in safety critical applications

Background to the invention

Solenoids are electro-mechanical transducers commonly used as controlling elements in fluid, pneumatic or mechanical systems.

Many of these systems are critical either commercially or with regard to personal and environmental safety and as such the potential for solenoid failure is a hazard which has to be addressed when designing these systems.

Traditionally a solenoid with built in redundancy will have two individual coils which are electrically independent but act upon a common armature and are enclosed within a common housing.

The disadvantage of this arrangement is that any failure attributable to the armature or mechanical damage to the housing will negate the redundancy function of the solenoid

Statement of the invention

According to the invention there is provided a solenoid comprising: a housing enclosing a copper wound coil. An armature which can slide freely within the coil and under the influence of a magnetic field generated when a current is passed through it The configuration of the housing is such that two or more solenoids can be placed in longitudinal contact with each other and their alignment will be maintained The configuration of the Armature is such that when two or more solenoids are in contact with each other the armatures are in contact and motion in one will be sensed in the others

Brief Description of the Drawings

Fig.1 illustrates a cross section of a single solenoid according to the invention Fig.2 illustrates a single solenoid in its second position with the coil energised Fig. 3 illustrates the embodiment in a typical dual redundancy configuration

Detailed Description

The solenoid consists of a tubular housing 1 which encloses the wire coil 2 Through the centre of the coil is the metallic core 3 which is free to move under

the influence of the coils magnetic field

The distance the core can move is determined by the air gap 4 In Fig.2 the coil is energised, the metallic core has been drawn by the magnetic field and now extends beyond the limits of the housing. This extension of the core is typically what gives the solenoid its function In Fig 3 two solenoids are held together with the forward face of the aft solenoid in contact with rear face of the forward solenoid 6 The housing may or may not include a method of connecting or aligning multiple solenoids With the housings in contact the design of the invention will ensure that the cores (3a & 3b) are held in contact and in this configuration it can be seen that energising either coil will result in the extension of the core thereby giving the arrangement its redundancy function The cores may or may not include a method of being physically connected to enable double acting push or pull operation Other multiples of solenoids may be employed to increase redundancy More than one coil may be energised at one time to increase the force produced