GB2211239A

GB2211239A - Door handle incorporating an electrically operable clutch

Info

Publication number: GB2211239A
Application number: GB8724364A
Authority: GB
Inventors: Donald Thomas Talbot; Walter John Aston
Original assignee: Yale Security Products Ltd
Current assignee: Security Products UK Ltd
Priority date: 1987-10-17
Filing date: 1987-10-17
Publication date: 1989-06-28
Also published as: GB8724364D0

Abstract

A door handle (10) is formed with a blind bore (11) which houses an electromagnetic clutch. The electromagnet of this clutch includes a sleeve (12) which is notched (12a) to provide a drive connection with a notch (18b) on an end member (18) which is spring-loaded towards the sleeve (12) and houses a drive dog (20) which is repelled into a matching recess at the blind end of the bore (11) when the electromagnet is energised. The end member (18) is free to move sufficiently far to disengage the finger (18a) thereon from the notch (12a) and prevent a driving connection between the handle and the sleeve being established by displacement of the drive dog by tapping rather than by electromagnet energisation. <IMAGE>

Description

DOOR HANDLE INCORPORATING AN ELECTRICALLY OPERABLE CLUTCH This invention relates to a door handle incorporating an electrically operable clutch.

I A door handle has already been proposed in which the handle is formed with a blind bore in which an electromagnetic clutch is formed. The clutch includes a steel sleeve containing an electromagnet and having means for coupling it at one end to a spindle. A drive recess is formed in the blind end of the bore and a complementary drive dog is slideably mounted in an end member on the other end of the sleeve, a driving connection being provided between the end member and the sleeve. The drive dog incorporates a permanent magnet such that when the electromagnet is not energised the drive dog is attracted towards the electromagnet and is held clear of the drive recess. When the electromagnet is energised, the drive dog is repelled therefrom into the recess so as to provide a driving connection between the handle and the end member.

Such a handle can be mass produced very inexpensively so that it can be used in conjunction with a simple electronic circuit for energising the electromagnet to provide a low cost electronic lock.

However, it has been found that it is possible to open the lock simply by tapping the handle while turningit. This can cause the drive dog to move into the recess where it becomes trapped by the torque applied to the handle.

It is an object of the invention to provide a simple construction in which this problem is overcome in a simple and efficaceous manner.

In accordance with the invention there is provided the combination of a handle formed with a blind bore having a drive recess formed at its blind end, an electromagnet, mounted in said bore and having. at one end means for drivingly coupling it to an operating spindle, an end member mounted in the bore between the blind end thereof and the other end of the electromagnet, a drive .dog slidably mounted in a passage in said end member and having a permanent magnet thereon such that the drive dog can be repelled from the electromagnet into said recess to provide a driving ' connection between the handle and the end member, characterised in that the end member is free to move axially in the bore and has a drive element facing a complementary drive element on the electromagnet, resilient means being provided to urge the end member towards the electromagnet, the permitted axial travel of the end member being sufficient to disengage said drive elements.

With such an arrangement, any attempt to engage the drive member with the recess by tapping the handle will be foiled by virtue of the fact that the end member will also move axially and break the driving connection formed by said drive elements.

In the accompanying drawings, Figure 1 is a longitudinal section through one example of a handle in accordance with the invention; Figure 2 is a fragmentary section on line 2.2 in Figure 1; and Figure 3 is an exploded fragmentary view showing some of the internal components of the handle.

As shown, the handle 10 is formed with a blind bore, at the blind end of which there is formed a drive recess 11 of non-circular, for example cruciform, cross sectional configuration. Located in the bore and rotatable therein, is an electromagnet consisting of a steel sleeve 12 containing a solenoid 13 on an iron core piece 14. Attached to the core at the end opposite the blind end of the bore is a drive piece 15 which has a square socket therein to receive a square spindle 16. The drive piece 15 is retained by a circlip 17 but is free to rotate in the bore.

At the other end of the electromagnet, an end member 18 is contained in the bore. This end member is formed with a passage 18a of the same cross-sectional shape as the recess 11. This end member 18 is axially slidable in the bore and has a projecting drive element in the form of a finger 18a facing towards the electromagnet.

This finger 18a can be received by a complementary drive element on the sleeve, formed by a notch 12a in the end thereof. The end member 18 is lightly urged towards the electromagnet by a light spring 19.

Axially slidably mounted in the end member is a drive dog 20 which has a permanent magnet disc 21 attached to it. This attracts the dog 20 towards the electromagnet and maintains the dog 20 clear of the recess 11 when the electromagnet is not energised. Energisation of the electromagnet in the appropriate sense, will, however, cause the drive dog to be repelled towards the recess so that it can enter the recess and provide a driving connection between the handle 10 and the member 18 and hence between the handle and the spindle.

If an attempt is made to open the door by tapping the handle in such a way that the drive dog 20 rebounds and enters the recess, this will also cause the end member 18 to rebound. This will cause the finger 18a to move clear of the notch 12a so that no driving connection exists between the end member and the sleeve 12. As a result the torque required to trap the dog 20 in the -recess 11 cannot be applied as the member 18 becomes free to turn.

It will thus be seen that the problem of preventing unauthorised opening of a door on which the handle is fitted, by tapping of the handle, is avoided.

Claims

1. The combination of a handle formed with a blind bore having a drive recess formed at its blind end, an electromagnet mounted in said bore and having at one end means for drivingly coupling it to an operating spindle, an end member mounted in the bore between the blind end thereof and the other end of the electromagnet, a drive dog slidably mounted in a passage in said end member and having a permanent magnet thereon such that the drive dog can be repelled from the electromagnet into said recess to provide a driving connection between the handle and the end member, characterised in that the end member is free to move axially in the bore and has a drive element facing a complementary drive element on the electromagnet, resilient means being provided to urge the end member towards the electromagnet, the permitted axial travel of the end member being sufficient to disengage said drive elements.

2. The combination claimed in claim 1 in which said electromagnet includes a sleeve of ferromagnetic material rotatably mounted in the bore in the handle and attached to said coupling means, said drive element comprising a finger on said end member and said complementary drive member being a notch in the end of said sleeve.

3. The combination as claimed in claim 1 or claim 2 in which said drive recess, said drive dog and said passage in said member are all of cruciform cross-section.

4. The combination of a door handle and an electromagnetically operable clutch substantially as hereinbefore described with reference to and as shown in the accompanying drawings.