GB2132416A - Electromagnetic actuator - Google Patents

Abstract

An electromagnetic actuator includes a solenoid assembly 10 defining a surface 11 presented to a flat armature. The surface includes pole faces 12 disposed in spaced side by side relationship extending alternately from opposite edges 13, 14 of said surface. <IMAGE>

Description

SPECIFICATION Electromagnetic actuators This invention relates to an electromagnetic actuator comprising an armature of plate like form and a solenoid assembly defining pole pieces which when a winding of the assembly is supplied with electric current, assume opposite magnetic polarity thereby creating a magnetic fieid to attract the armature towards the pole pieces.

The object of the invention is to provide such an actuator in a simple and convenient form.

According to the invention in an electromagnetic actuator of the kind specified said solenoid assembly on its surface presented to the armature, defines a plurality of pole faces disposed in spaced side by side relationship across said surface, said pole faces extending alternately from opposite edges of said surface and overlapping each other.

An example of the solenoid assembly of an electromagnetic actuator in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a plan view looking onto the surface of the solenoid assembly which is presented to the armature, Figure 2 is a view in the direction of the arrow A of Figure 1 showing also the armature which is not shown in Figure 1, Figure 3 is a view in the direction of the arrow B of Figure 1, and Figures 4, 5, 6 and 7 are side views respectively of laminations forming part of the assembly.

Referring to the drawings, the actuator comprises an armature 9 which is of plate like form and is formed from magnetisable material.

The actuator also includes a solenoid assembly which is generally indicated at 10 and this defines a surface 11 presented in use, to the armature. As will be seen from Figure 1, the aforesaid surface is of generally rectangular form.

The surface 11 is formed by a plurality of pole faces which are generally indicated at 12, the remaining portion of the surface conveniently being composed of a synthetic resin material which is utilised as will be described, to encapsulate the various components of the assembly. The pole faces extend alternately from a pair of opposite sides 13, 14 of the surface 11 and they are disposed in spaced side by side relationship.

The three pole pieces which are shown in the lower part of Figure 1 have additional lines to indicate their construction. Each pole face is made up by the edges of a plurality of laminations disposed in side by side relationship and each complete pole face that is to say an intermediate pole face, is made up of five laminations of differing shape, the effect being to provide a tapered pole face. Figure 4 shows in side elevation the lamination 15, Figure 5 shows in side elevation the lamination 1 6 and Figure 6 shows the lamination which is referenced 17 and Figure 7 shows the lamination which is referenced 18.The laminations are assembled in the appropriate order and can be secured together by means of fixing bolts which extend through apertures 1 9 in the laminations or other methods of securing the laminations together may be employed. The stack of laminations defines a core shown at 20 in Figure 3, for a winding 21 and when the winding is supplied with electric current, adjacent pole faces assume opposite magnetic polarity and create magnetic fields which attract the armature 9 to the surface 11.

It would clearly be difficult to wind the winding 21 with the laminations in assembled relationship. The usual procedure is therefore adopted of winding the winding 21 about a former 22 and then the laminations are inserted in the former to construct the solenoid assembly.

It would be impossible to pass the laminations through the former and hence each lamination is divided so that the two portions of each lamination can be assembled from the opposite ends of the former. It is arranged that the divisions between the laminations which will be adjacent to each other in the completed solenoid assembly are offset, this being the usual practice when constructing laminated cores.

It will be noted from Figure 1 that the gaps between adjcent pole faces at least over the overlapping portions thereof are substantially equal and it is across these gaps that the flux passes. If the armature 9 is closer to the face 11 than the distances between adjacent pole faces, most of the flux will pass between the pole faces and the armature 9 so that there will be a high attractive force between the solenoid assembly and the armature.

As previously mentioned the assembly is encapsulated in a synthetic resin material such as an epoxy resin.

Claims

1. An electromagnetic actuator comprising an armature of plate like form and a solenoid assembly defining pole pieces which when a winding of the assembly is supplied with electric current assume opposite magnetic polarity thereby creating a magnetic field to attract the armature towards the pole pieces, said solenoid assembly on its surface presented to the armature defining a plurality of pole faces disposed in spaced side by side relationship across said surface, said pole faces extending alternately from opposite edges of said surface and overlapping each other.

2. An actuator according to Claim 1 in which each pole face is composed of the edges of a plurality of laminations which are disposed in side by side relationship to form the pole face.

3. An actuator according to Claim 2 in which each pole face is tapered.

4. An actuator according to Claim 3 in which the portion of the surface not defined by the pole faces is formed by synthetic resin material.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electromagnetic actuators This invention relates to an electromagnetic actuator comprising an armature of plate like form and a solenoid assembly defining pole pieces which when a winding of the assembly is supplied with electric current, assume opposite magnetic polarity thereby creating a magnetic fieid to attract the armature towards the pole pieces. The object of the invention is to provide such an actuator in a simple and convenient form. According to the invention in an electromagnetic actuator of the kind specified said solenoid assembly on its surface presented to the armature, defines a plurality of pole faces disposed in spaced side by side relationship across said surface, said pole faces extending alternately from opposite edges of said surface and overlapping each other. An example of the solenoid assembly of an electromagnetic actuator in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a plan view looking onto the surface of the solenoid assembly which is presented to the armature, Figure 2 is a view in the direction of the arrow A of Figure 1 showing also the armature which is not shown in Figure 1, Figure 3 is a view in the direction of the arrow B of Figure 1, and Figures 4, 5, 6 and 7 are side views respectively of laminations forming part of the assembly. Referring to the drawings, the actuator comprises an armature 9 which is of plate like form and is formed from magnetisable material. The actuator also includes a solenoid assembly which is generally indicated at 10 and this defines a surface 11 presented in use, to the armature. As will be seen from Figure 1, the aforesaid surface is of generally rectangular form. The surface 11 is formed by a plurality of pole faces which are generally indicated at 12, the remaining portion of the surface conveniently being composed of a synthetic resin material which is utilised as will be described, to encapsulate the various components of the assembly. The pole faces extend alternately from a pair of opposite sides 13, 14 of the surface 11 and they are disposed in spaced side by side relationship. The three pole pieces which are shown in the lower part of Figure 1 have additional lines to indicate their construction. Each pole face is made up by the edges of a plurality of laminations disposed in side by side relationship and each complete pole face that is to say an intermediate pole face, is made up of five laminations of differing shape, the effect being to provide a tapered pole face. Figure 4 shows in side elevation the lamination 15, Figure 5 shows in side elevation the lamination 1 6 and Figure 6 shows the lamination which is referenced 17 and Figure 7 shows the lamination which is referenced 18.The laminations are assembled in the appropriate order and can be secured together by means of fixing bolts which extend through apertures 1 9 in the laminations or other methods of securing the laminations together may be employed. The stack of laminations defines a core shown at 20 in Figure 3, for a winding 21 and when the winding is supplied with electric current, adjacent pole faces assume opposite magnetic polarity and create magnetic fields which attract the armature 9 to the surface 11. It would clearly be difficult to wind the winding 21 with the laminations in assembled relationship. The usual procedure is therefore adopted of winding the winding 21 about a former 22 and then the laminations are inserted in the former to construct the solenoid assembly. It would be impossible to pass the laminations through the former and hence each lamination is divided so that the two portions of each lamination can be assembled from the opposite ends of the former. It is arranged that the divisions between the laminations which will be adjacent to each other in the completed solenoid assembly are offset, this being the usual practice when constructing laminated cores. It will be noted from Figure 1 that the gaps between adjcent pole faces at least over the overlapping portions thereof are substantially equal and it is across these gaps that the flux passes. If the armature 9 is closer to the face 11 than the distances between adjacent pole faces, most of the flux will pass between the pole faces and the armature 9 so that there will be a high attractive force between the solenoid assembly and the armature. As previously mentioned the assembly is encapsulated in a synthetic resin material such as an epoxy resin. Claims

1. An electromagnetic actuator comprising an armature of plate like form and a solenoid assembly defining pole pieces which when a winding of the assembly is supplied with electric current assume opposite magnetic polarity thereby creating a magnetic field to attract the armature towards the pole pieces, said solenoid assembly on its surface presented to the armature defining a plurality of pole faces disposed in spaced side by side relationship across said surface, said pole faces extending alternately from opposite edges of said surface and overlapping each other.

2. An actuator according to Claim 1 in which each pole face is composed of the edges of a plurality of laminations which are disposed in side by side relationship to form the pole face.

3. An actuator according to Claim 2 in which each pole face is tapered.

4. An actuator according to Claim 3 in which the portion of the surface not defined by the pole faces is formed by synthetic resin material.

5. An electromagnetic actuator comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.