GB2229040A

GB2229040A - Solenoid assembly

Info

Publication number: GB2229040A
Application number: GB8905427A
Authority: GB
Inventors: Alan Godfrey; Barry Shaun Cowley
Original assignee: PED Ltd
Current assignee: PED Ltd
Priority date: 1989-03-09
Filing date: 1989-03-09
Publication date: 1990-09-12
Anticipated expiration: 2009-03-09
Also published as: GB8905427D0; GB2229040B

Abstract

The solenoid assembly comprises a coil 18 mounted in a frame 10 provided with an integral wall 26 in which a bearing 22 acting as a guide for an armature 14 is mounted. When the solenoid is energised, the armature is drawn into the solenoid thereby compressing a coil spring 28 which may engage contacts to operate a buzzer or light. The withdrawal of the armature may allow a door to open. <IMAGE>

Description

Title Solenoid Assembly Field of the invention This invention relates to a solenoid assembly.

Background to the invention A typical known solenoid assembly has a mounting frame which firstly supports a yoke within which is mounted a coil wound on a bobbin and secondly supports a separate guide such as a ccllar fcr guiding tne reverent o; an armature which is attracted towards the coil when the solenoid is energised. It is a object of this invention to provide an improved and si.mplified solenoid assembly.

The invention According to the invention, there is provided a solenoid assembly comprising an armature means slidable relative to and in part guided by a coil means, and connections for enabling an electric current to flow at the coil means in order to attract the armature thereto, characterised by a support frame of unitary material having a region for locating the coil means and an integral upstanding portion providing an outboard guide for the armature means and through which the armature means passes.

In accordance with one aspect of the invention, the support frame is formed entirely from a magnetically susceptible material (hereinafter magnetic material) and the coil means comprises a coil which is wound on a bobbin of non-magnetic material mounted within the first region of the support.

In accordance with another aspect of the invention, the support frame is integrally formed with a bobbin of nonmagnetic material on which the coil is wound, and a separate sub-frame of magnetic material is carried by the support frame to provide a magnetic flux path.

The armature means preferably comprises a body (armature) of magnetic material extending from within the coil means into the space between the first region of the support frame and the upstanding portion, and a plunger which projects on the side of the armature remote fron the coil means (the outboard side) and is guided by said upstanding portion.

The armature and the plunger may be integrally formed, a shoulder between said armature and plunger providing an end stop abutment for limiting movement of the armature means away from the coil means. Alternatively, the armature and the plunger may be separate parts, interconnected by means such as a radial pin within the armature, and either the armature may act as the end stop abutment or a radial shoulder or protrusion on the plunger may act as the end stop abutment.

In a preferred embodiment, the upstanding portion of the support frame has a large enough aperture to allow the armature to pass tPethrough for assembly purposes, and also for the same reason to allow passage of a push-off coil spring whch may be provided around the armature. In this case, the afore-mentioned end stop abutment on the armature means may act against an apertured bearing element fitted to the remote side of the upstanding portion and allowing only the end portion of the plunger to pass therethrough. When the upstanding portion is of magnetic material, the apertured bearing element must be of non-magnetic material in order magnetically to isolate the plunger from the support frame. The said apertured bearing element may have claws push fitting into and spring securing the bearing element in the large aperture in the upstanding portion.

The large aperture in the upstanding portion enables the armature means to be axially assembled into the coil means through said upstanding portion.

Any other convenient bearing element, such as a sleeve, may be provided as a plunger guide at the upstanding portion of the support frame, and be rivetted, bolted, glued or otherwise fixed to said upstanding portion in any convenient manner.

When a normally open contact is required to close (for example to operate a buzzer or light) when the solenoid is energised and the plunger withdrawn (for example to allow a door to open), a pair of electrically isolated conductive contacts may be provided on the end face of the coil former (bobbin), together with associated protruding integral connecting pins bridged by a conductive elenent carried by the armature means when the solenoid is energised. Said conductive element may be constituted, for example, by the afore-mentioned push-off spring which pushes the armature outwards from the coil means when the solenoid is de-energised.When the support frame is of magnetic material, parts thereof may be cut-away to accommodate the contact connecting elements, which project from the end face of the coil former through non-magnetic shielding elements fitted into and extending through said cut-aways.

References herein to non-magnetic material generally indicate a hard wearing, resilient plastics material such as an acetal resin or Nylon (Trade Mark).

In the case of a support frame of magnetic material, this is preferably of a squared S-shape, with one open ended Ushape accommodating the coil means and one oppositely facing open sided U-shape accommodating the armature.

A preferred method of manufacture e.,.ploying a magnetic support frame is as follows:1. Pierce a magnetic strip with required apertures and bend to the required S-shape; 2. Wind the coil on a plastics bobbin having a chimney at one end; 3. Locate the coil assembly in one U-shape of the support frame with the chimney located and urged into an aperture in the intermediate wall of the support frame by a leaf spring located between the coil assembly and the end wall of the U-shape; 4. Close an aperture in the end wall of the U-shape by fixing in position an in-board end stop which protrudes through said aperture to locate the adjacent end of the bobbin; 5. Insert the armatureXplunger/coil spring assembly through the large aperture in the other end wall of the support frame; 6.Locate and fix at said other end wall the bearing element for the plunger, thereby also providing an outboard end stop; and 7. Make electrica] connections to the coil and to the bobbin laterally at opposite sides of the support frame, if necessary bending round into the region containing the coil.

Description of embodiments A solenoid assembly in accordance with the invention is exemplified with reference to the accompanying drawings, in which: Figure 1 shows a preferred embodiment in side elevation; Figure 2 shows the assembly in front elevation; Figure 3 shows the assembly in vertical cross section; Figure 4 shows a modification in vertical cross section; Figures 5A and 5B show alternative possible electrical contact arrangements for the solenoid assembly; Figures 6A, 6B and 6C show differing possible arrangements of in-board end stop; and Figure 7 shows a bearing element which can constitute an out-board end stop.

The solenoid assembly illustrated in Figures 1 to 3 comprises a magnetic support frame 10, generally of a squared S-shape, having a coil means 12 fitted in one U shape and an armature 14 extending from within the coil means into the other oppositely facing U-shape.

Ihe ccii means 12 comprises a bobbin 16 of resilient, hard wearing plastics material such as acetal or Nylon (Trade Mark), on which is wound a coil 18 (see Figure 3).

The armature 14 is integrally formed with a plunger 20 which projects axially from the outboard face of the armature, This plunger 20 is guided by a plastics bearing element 22, for example of acetal or Nylon (Trade :raj which has claws 24 enabling said element to be press fitted into and spring secured in a relatively large aperture provided in the end wall 26 of the support frame 10. Figure 7 shows the bearing element 22 as seen in an end view of the solenoid assembly.

A push-off coil spring 28, which can serve as a contact maker as well as for biassing the armature 14 out of the coil 18 when the solenoid is de-energised, is carried by the armature.

The bearing element 22 acts as an end stop limiting movement of the armature in the outboard direction, the shoulder 30 between the armature 14 and the plunger 20 serving as an end stop abutment.

On the in-board side, movement of the armature 14 is limited by an end stop element 32 fitted through a smaller aperture in the other end wall 34 of the support frame 10.

This end stop element, which may be fixed in position by peening 31, as shown in Figure 6A, by a circlip 33 as shown in Figure 6B, or by internal rivetting as shown at 35 in Figure 6C, protrudes into the central opening in the end of the coil former or bobbin 16, in order to assist in locating it in position.

The location of the coil means 12 is completed at the intermediate wall 36 of the support frame 10, where a chimney 38 formed on the outside end face of the bobbin 16 is fitted into an aperture in the intermediate wall which also allows passage of the armature 14 from within the coil means into the U-space terminated by the end wall 26 of the support frame.

Terminal elements for the solenoid assembly are provided in the region of the intermediate wall 36 of the frame support 10.

Thus, referring first to Figure 5A, in an arrangement having four terminal elements, two such elements with contacts 40 are provided for enabling energisation of the coil 18 and two normally open contacts 42 are provided for enabling operation of an auxiliary device such as a buzzer or warning light. The contacts 42 are closed, when the solenoid is energised, by a conductive element 44, which in practice is constituted by the afore-mentioned push-off coil spring 28. Figure 5B shows an arrangement for a similar purpose, but having only three contacts 46. It will be clear that if auxiliary switching is not required, the solenoid assembly requires only two terminal elements.

Figures 1 and 2 show a solenoid assembly having three terminal elements 48, 50, 52, with an optional fourth element shown in broken line at 54 in Figure 2. In Figure 1, terminal element 48 is visible, but hides terminal element 50 on the other side of the assembly, whilst terminal 52 is shown in broken line because it also is located on the other side of the assembly. The terminal elements are fixed to the end face of the bobbin 16, and at least the terminal elements 48 and 50 have connecting parts protruding through cut-away regions of the intermediate wall 36 of the support frame 10 and shielded from said support frame by plastics shielding elements fitted into the recesses, as indicated by way of example at 56 in Figure 1.

Figure 4 of the accompanying drawings shows a modification wherein the support frame 60 is of plastics material and incorporates the bobbin 16, and the yoke for the coil means 12 is a separate element 62 of magnetic material secured to the support frame around the coil 18. Other reference numerals marked in Figure 4 indicate parts analogous to those described with reference to Figures 1 to 3.

A preferred method of producing the solenoid assembly of Figures 1 to 3 is to pierce and bend a strip of magnetic material to form the support frame 10, wind the coil 18 on the bobbin 16, locate the coil means in the frame with the aid of leaf spring 64 shown in Figure 3, complete location of the coil means by fixing the end stop 32 in position, add the push-off coil spring 28 to the integral armature/plunger 14, 20, locate this armature/plunger/ spring unit into the coil means by axial insertion through the aperture in the out-board end wall 26 of the support frame, fix the bearing element/end stop 22 in position, and fix in position the required terminal elements 48, 50, 52, if necessary bending the connecting parts of said terminal elements round into the space containing the coil.

It will be appreciated that the above-described embodiments may be modified in various ways within the scope of the invention hereinbefore described.

Claims

Claims:

1. A solenoid assembly comprising an armature means slidable relative to and in part guided by a coil means1 and connections for enabling an electric current to flow in the coil means in order to attract the armature thereto, characterised by a support frame of unitary material having a first region for locating the coil means therein and an integral upstanding portion providing an outboard guide for the armature means and through which the armature means passes.

2. A solenoid assembly according to Claim 1, wherein the support frame is formed entirely from a magnetically susceptible material and the coil means comprises a coil which is wound on a bobbin of non-magnetic material mounted within the first region of the support.

3. A solenoid assembly according to Claim 2, wherein the support frame is of a squared S-shape, defining two oppositely directed openings, one accommodating the coil means and the other accommodating the armature means.

4. A solenoid assembly according to Claim 1, wherein the support frame is integrally formed with t bobbin of.nonmagnetic material on which a coil is wound, and a separate sub-frame of a magnetically susceptible material is carried by the support frame to provide a magnetic flux path.

5. A solenoid assembly according to Claim 4, wherein the non-magnetic material of which the support frame is formed from wear-resistant, resilient plastics material.

6. A solenoid assembly according to any one of the preceding claims, wherein the armature means comprises a body of a magnetically susceptible material extending from within the coil means into the space between the first region of the support frame and the upstanding portion, and a plunger which projects on the side of the armature remote from the coil means (the outboard side) and is guided by said upstanding portion.

7. A solenoid assembly according to Claim 6, wherein the armature and the plunger are integrally formed, a shoulder between said armature and said plunger providing an end stop abutment for limiting movement of the armature means away from the coil means.

8. A solenoid assembly according to Claim 6, wherein the armature and the plunger are separate but interconnected parts and wherein either the armature or a shoulder or protrusion on the plunger acts as an end stop abutment for limiting movement of the armature means away from the coil means.

9. A solenoid assembly according to any one of the preceding claims, wherein the upstanding portion of the support frame includes an aperture through which the armature means can pass for assembly purposes.

10. A solenoid assembly according to any one of the preceding clam, wherein a push-off coil spring is provided around the armature means, and the upstanding portion of the support frame includes an aperture through which the armature means and the coil spring can pass together for assembly purposes.

11. A solenoid assembly according to Claim 9 or Claim 10, wherein an end stop abutment provided on the armature means for limiting movement of the armature means away from the coil means acts against an apertured bearing element fitted to the remote side of the upstanding portion and allows only the outboard end portion of the armature means to pass therethrough.

12. A solenoid assembly according to Claim 11, wherein the apertured bearing element has claws push fitting into and spring securing the bearing element in the aperture in the upstanding portion of the support frame.

13. A solenoid assembly according to any one of the preceding claims, wherein the coil means comprises a coil wound on a bobbin, a pair of electrically isolated conductive contacts being provided on the end face of the bobbin, together with associated protruding integral connecting pins which, when the solenoid is energised, are bridged by a conductive element carried by the armature means.

14. A solenoid assembly according to Claim 13, wherein a push-off coil spring is provided around the armature means, which coil spring constitutes the conductive element and pushes the armature means outwards from the coil means when the solenoid is de-energised.

15. A solenoid assembly accordng-to Claim 13 or Claim 14, wherein the support frame is formed from a magnetically susceptible material and parts of the said support frame are cut away to accommodate the connecting pins, which pins project from the end face of the coil former through non-magnetic shielding elements fitted into and extending through the cut-away regions of the support frame.

16. A solenoid assembly according to any one of the preceding claims and substantially as herein described with reference to the accompanying drawings.

17. A method of manufacture of a solenoid assembly comprising the following steps:a) Piercing a strip of a magnetically susceptible material with required apertures and bending the strip into an S-shape to form a support frame, having two oppositely directed openings; b) Winding a coil on a bobbin having a chimney at one of its ends; c) Locating the coil and bobbin (the coil assembly) in one of the openings in the support frame with the chimney located and urged into an aperture in an intermediate wall of the support frame by a leaf spring located between the coil assembly and an end wall of the support frames d) Closing an aperture in the end wall of the opening by fixing in position an in-board end stop which protrudes through said aperture to locate the adjacent end of the bobbin: e) Inserting an armature means into the other opening in the support frame through an aperture in the end wall of the support frames f) Locating and fixing at said end wall of the support frame a bearing element for the armature means, thereby also providing an out-board end stopt and g) Making electrical connections to the coil and to the bobbin on opposite sides of the support frame.