GB2204356A

GB2204356A - Locking device for mutually pivotable members

Info

Publication number: GB2204356A
Application number: GB08710762A
Authority: GB
Inventors: Adrian Douglas Stokes; David Peter Allmand Thompson
Original assignee: GORDON RUSSELL PLC
Current assignee: GORDON RUSSELL PLC
Priority date: 1987-05-07
Filing date: 1987-05-07
Publication date: 1988-11-09
Anticipated expiration: 2007-05-07
Also published as: GB2204356B; GB8710762D0

Abstract

A device (1) for locking two mutually pivotable members such as the back and seat of a chair, in any of a plurality of positions comprises a ball member (6); a first element (2) for connection to one of said members; a second element (3), for connection to the other of said members and having a through hole, in which the ball member is located, and a third element (4) for rotation with respect to said second element between two positions in one of which (Fig. 1B) the first and second elements are able to pivot while in the other position (Fig. 1A) the ball member (6) is lockingly engaged by both the first element and the third element. The embodiment shown has flat elements engaging (at 7, 8) the pivot axis of the members. The element (2) has a plurality of recesses while the element (4) has a recess adjoining a shallower channel. The elements (3, 4) may alternatively have a curved slot and channel respectively. In a further embodiment the three elements are formed as coaxial cylindrical members. <IMAGE>

Description

LOCKING DEVICE The present invention relates to a device for locking two mutually rotatable members in any of a plurality of positions.

The present invention provides a device for locking two mutually rotatable members in any of a plurality of positions the device comprising a ball member; a first element for connection to one of said members; a second element for connection to the other of said members and having a through hole in which the ball member is located, and a third element for rotation with respect to said second element between two positions, in one of which the first and second elements are able to rotate with respect to each other and in the other of which the ball member is engaged by both the first element and the third element thereby preventing rotation of said first element with respect to the second element.

The three elements may consist of three co-axial cylindrical members. In an alternative embodiment of the invention, these elements consist of three plates, at least two of which are preferably mounted for rotation about a common axis.

In one embodiment of the present invention, a plurality of ball seats is provided in the third element, one of which being brought into engagement with the ball member upon rotation of the third element to said other position.

In an alternative embodiment, a plurality of ball seats is provided on the first member and the third element has an abutment surface which, on rotation of the third element to said other position, urges the ball member into and retains it in one of the ball seats.

It is preferred that in those embodiments in which the three elements are cylindrical in form, the ball runs in a channel in the first or the third element which extends parallel to the common rotational axis of the elements. In this case, the second element is provided with a slot which extends obliquely with respect to this rotational axis.

Rotation of the second element with respect to that element bearing the channel causes the ball to move along the channel.

In those embodiments in which the channel is provided in the first element, the third element preferably consists of an outer sleeve, an arc of its internal surface being raised and provided with the plurality of ball seats extending along its length.

In those embodiments of the device in which the channel is provided in the third element, the plurality of ball seats is preferably provided on the first element. In this case, the third element has a raised surface which extends along its length and is brought into engagement with the ball member urging it into and retaining it in one of the seats, upon rotation of the third element into said other position.

In those embodiments of the present invention in which the three elements are constituted by flat plates, the through hole in the second element may comprise a curved slot of width commensurate with the diameter of the ball.

Alternatively, it may be a circular hole having a diameter commensurate with that of the ball.

In the former case, the ball runs in a curved channel in the first element, the centre of curvature of the slot and the channel being in opposite directions such that rotation of the second plate with respect to the first causes the ball to move along the curved channel. The third element is mounted adjacent the second for rotation with respect to the second element and has a recess in that surface facing the second element in which the ball member is located when the third element is in said one position. A plurality of ball seats is provided adjacent the recess on the third element such that rotation of the third element into said other position brings one of these seats into engagement with the ball.

In those embodiments in which the second member has a circular through hole, a plurality of ball seats is preferably provided on the first element. The third element is conveniently mounted for rotation with respect to the first element about a common axis, with the second member located therebetween. The third element is provided with a recess the depth of which is greater than that of the ball seats to enable the ball member to move without engagement therewith. A surface raised with respect to the bottom of the recess is provided on the third element adjacent the recess and bears against the ball member when the third element is in said other position, to cause the ball to pass through the hole and into engagement with one of the ball seats.

The present invention finds particular application as a locking device for a tiltable chair back. Such embodiments permit the locking of the chair back in any of a plurality of orientations with continuous movement of the back between these positions: Embodiments of the present invention have the advantage of being relatively compact and cheap to produce.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1A shows a cross section through an embodiment of the device of the present invention in a locking position.

Fig. 1B shows a cross section through the embodiment of Fig. 1A in a release position.

Fig. 2 shows a plan view of each of three elements of the embodiment of Figs. 1A and B; Fig. 3A shows diagramatically the embodiment of Figs.

1A, 1B and 2 mounted to an office chair; Fg. 3B shows a side view of a portion of the arrangement of Fig. 3B in greater detail; Fig. 4 shows, in plan view, three elements of an embodiment similar to that shown in Figs. 1A, B and 2; Fig. 5 shows an exploded view of a further embodiment of the device of the present invention; Fig. 6 shows an exploded view of a still further embodiment of the device of the present invention; Fig. 7A shows a cross section through yet another embodiment of the present invention, in the locking position; Fig. 7B shows a cross section through the embodiment of Fig. 7A in the release position, and Fig. 8 shows a plan view of three elements of the embodiment of Figs. 7A and 7B.

Figures 1A, 1B and 2 illustrate a preferred embodiment of a locking device 1 of the present invention.

This device 1 comprises three plates 2 to 4, the middle one of which has a through hole 5 in which a ball bearing 6 is housed. The diameter of the hole 5 in plate 3 is commensurate with that of the ball bearing 6. The other two plates 2 and 4 are provided with through holes 7 and 8 which permit them to be mounted for rotation on a common axle 15 (see Figs. 3A and 3B) with plate 3 located between them.

Plates 2 and 4 are thereby able to rotate with respect to each other and to plate 3 with which they are in wiping contact.

Plate 2 is provided with a plurality of ball seats 9 arranged on the arc of a circle the centre of whichcoincides with that of through hole 7. Plate 4 is provided with a recess 10 from which a channel 11 extends. The centre line of this channel 11 is the arc of a circle whose centre coincides with that of through hole 8 and whose radius is identical with that of the centre line of the ball seats 9.

The sum of the depth of plate 3 and the depth of the recess 10 is commensurate with the diameter of the ball bearing 6. Thus, with the plate 4 arranged so that the recess 10 is in register with through hole 5 in plate 3, plate 2 is free to rotate with respect to plate 3. When locking plate 4 is rotated so as to bring the ball 6 into channel 11, the ball is caused to protrude through the plate 3 and into engagement with whichever ball seat is in closest alignment with hole 5. Thus, the present device allows members connected to plates 2 and 3 to rotate freely with respect to each other when the locking plate 4 is in a release position with recess 10 in alignment with hole 5, and their orientation to be secured by movement of the plate 4 to a locking position with the channel 11 in alignment with hole 5.

Figures 3A and 3B show the device of Figure 1 mounted to an office chair whose back 13 is biased to the upright position shown by means of a spring 14. In this arrangement, the plate 2 is mounted to the back 13 of the chair for rotation about axle 15. Ball retaining plate 3 is mounted to the seat 16 of the chair and locking plate 4 to axle 15 biased to locking position by means of a spring 17.

The locking plate 4 is brought to the release position B shown in Fig. 3B by means of a manual lever (not shown). This lever operates to rotate a cam 19 which acts on a lug 20 on plate 4 to rotate the plate 4 to this release position in which a recess in plate 4 is engaged by a spring member 18. The plate 4 is thus retained in the release position B until sufficient force is applied to it to overcome the action of the spring member 18. This is achieved by rotation of the cam 19 by means of the lever, the cam acting on a surface of the plate 4 adjacent the lug 2Q, as can be seen from Figure 3B. The locking plate 4 is then returned to the locking position A under action of spring 17.

When the plate 4 is in the release position B, pressure appied to the back of the chair against the force of the spring 14 will cause the plate 2 to rotate with respect to plate 3. When the back has reached a desired angle of tilt, operation of the lever to rotate plate 4 to the locking positon A will cause the ball 6 to engage that ball seat in closest alignment with it, thereby preventing further rotation of plate 2 and hence the- chair back 13.

In an alternative embodiment to that shown in Figures 1A, 1B, and 2, illustrated in Figure 4, the ball retaining plate 3 has an overall form similar to that of plates 2 and 4, having a through hole 12 to enable it to be mounted on the common axle 15. Further, the through hole 5 in plate 3 is frusto-conical, the smaller diameter being that adjacent the plate 2.

Also in this embodiment, the recess 10 in plate 4 is provided on the centreline of the plate and two channels 11 are provided which extend on either side of this recess.

This permits locking of the position of the ball by rotation of the plate 4 in either of two directions.

The embodiment shown in Figure 5 consists of three co-axially mounted cylindrical elements, a solid cylindrical member 22 and an inner and an outer sleeve member 23 and 24, respectively. The inner sleeve member 23 has a through slot 25 which extends obliquely with respect to its longitudinal axis, the width of the slot being commensurate with the diameter of a ball bearing 6 which is housed therein.

The outer sleeve 24 has a channel 30 which extends parallel to its longitudinal axis. In this embodiment, the channel 30 extends through the wall of the outer sleeve 24, although its width on the sleeve's external surface is less than the ball's diameter so that the ball is retained. The outer sleeve 24 is intended for mounting such that the channel 30 is provided at the or towards its lowest point so that the ball runs in this channel. Rotation of the inner sleeve member 23 with respect to the outer sleeve 24 causes the ball 6 to move along the channel 30 through its interaction with the slot 25.

The outer sleeve 24 is also provided on its internal surface with a raised abutment surface 31 which extends along its length adjacent the channel 30. The cylindrical member 22 has a plurality of ball seats 9 located in a line parallel with the longitudinal axis of this member.

On rotation of the outer sleeve 24 with respect to the inner sleeve 23, the abutment surface 31 is brought into contact with the ball 6 and pushes this into whichever ball seat is in closest alignment with the current position of the ball.

In mounting the device illustrated in Figure 5 to a chair of the type shown in Figures 3A and B, it is intended that the cylindrical member 22 be mounted to the seat 16 and the inner sleeve member 23 to the back 13.

In the embodiment shown in Figure 6, which also consists of three co-axial cylindrical elements 22, 23 and 24 the innermost, cylindrical member 22 is provided with a channel 40 parallel to its longitudinal axis. As in the embodiment of Figure 5, the inner sleeve 23 has an oblique slot 25 in which the ball is located, being promoted along the channel 40 on rotation of inner sleeve with respect to the cylindrical member 22.

The outer sleeve 24 is provided with a raised inner surface having a plurality of grooves constituting ball seats 9, the radii of the grooves being perpendicular to the longitudinal axis of the sleeve. Rotation of the outer sleeve 24 with respect to the inner sleeve 23 brings one of these grooves into contact with the ball 6 thereby fixing its position within the channel 40.

The cylindrical member 22 and inner sleeve 23 of the embodiment of Figure 6 are preferably connected to a chair in the manner described in relation to that of Figure 5.

The embodiment shown in Figures 7A, 7B and 8 operates in a similar manner to that shown in Figure 6.

However, in this case, the device consists of three flat plates 42 to 44 each having a through hole 47, 48 and 49 respectively. for mounting these plates on a common axle, such that plates 42 and 44 are in wiping contact with plate 43.

Plate 42 has a curved channel 50 and plate 43 a curved through slot 55 whose width is commensurate with the diameter of the ball bearing 6 which it houses. The centre of curvature of the curved channel 50 is on the opposite side thereof from that of the slot 45. Rotation of the plate 43 with respect to plate 42 causes the ball 6 to move along the channel 50.

The locking plate 44 has a recess 60, the depth of which is such as not to obstruct the free movement of the ball 6 along channel 50. Adjacent the recess 60 is a row of ball seats 9 arranged on a curve which mirrors that of the channel 50 on the plate 42. Rotation of the member 44 from the position in which the ball 6 is free to move in the recess 60, to that in which the ball seats 9 are in alignment with the channel 50 causes the ball to be engaged in that seat in closest alignment with its current position.

Claims

1. A device for locking two mutually rotatable members in any of a plurality of positions, the device comprising a ball member; a first element for connection to one of said members; a second element for connection to the other of said members and having a through hole in which the ball member is located, and a third element for rotation with respect to said second element between two positions, in one of which the first and second elements are able to rotate with respect to each other and in the other of which the ball member is engaged by both the first element and the third element thereby preventing rotation of said first element with respect to the second element.

2. A device as claimed in claim 1 wherein the three elements consist of three co-axial cylindrical members.

3. A device as claimed in claim 1 wherein the three elements consist of three plates.

4. A device as claimed in claim 3, wherein at least two of the plates are mounted for rotation about a common axis.

5. A device as claimed in any preceding claim wherein a plurality of ball seats is provided on the third element, one of which being brought into engagement with the ball member upon rotation of the third element to said other position.

6. A device as claimed in any one of claims 1 to 4 wherein a plurality of ball seats is provided on the first member and the third element has an abutment surface which, on rotation of the third element to said other position, urges the ball member into and retains it in one of the ball seats.

7. A device as claimed in claim 2 wherein a channel is provided in one of the first and third elements in which the ball run and which extends parallel to the common rotational axis of the elements and the second element is provided with a slot which extends obliquely with respect to this rotational axis, such that rotation of the second element with respect to that element bearing the channel causes the ball to move along the channel.

8. A device as claimed in claim 7 wherein the channel is provided in the first element and the third element consists of an outer sleeve which has an arc of its internal surface raised providing a plurality of ball seats extending along its length.

9. A device as claimed in claim 7 wherein the channel is provided in the third element, a plurality of ball seats is provided on the first element and the third element has a raised surface which extends along its length and is brought into engagement with the ball member to urge it into and retain it in one of the seats, upon rotation of the third element into said other position.

10. A device as claimed in claim 3 or 4 wherein the through hole in the second element comprises a curved slot of width commensurate with the diameter of the ball.

11. A device as claimed in claim 10 wherein a curved channel is provided in the first element, the centre of curvature of the slot and the channel being in opposite directions such that rotation of the second plate with respect to the first causes the ball to move along the curved channel.

13. A device as claimed in claim 11 or 12 wherein the third element is mounted adjacent the second element for rotation with respect thereto and has a recess in that surface facing the second element in which the ball member is located when the third element is in said one position.

14. A device as claimed in claim 13 wherein a plurality of ball seats is provided adjacent the recess on the third element such that rotation of the third element into said other position brings one of these seats into engagement with the ball.

15. A device as claimed in claim 3 or 4 wherein the through hole in the second element is a circular hole having a diameter commensurate with that of the ball.

16. A device as claimed in claim 15 wherein a plurality of ball seats is provided on the first element.

17. A device as claimed in claim 16 wherein the third element is mounted for rotation with respect to the first element about a common axis, with the second member located therebetween.

18. A device as claimed in claim 16 or 17 wherein the third element is provided with a recess the depth of which is greater than that of the ball seats to enable the ball member to move without engagement therewith, and a surface is provided on the third element adjacent the recess which is raised with respect to the bottom of the recess and bears against the ball member when the third element is in said other position, to cause the ball to pass through the hole and into engagement with one of the ball seats.

19. A device for locking two mutually rotatable members substantially as herein described with reference to any of Figures lA, 1B, 2 and 4 to 8 with or without reference to Figures 3A and 3B of the accompanying drawings.

20. A locking device for a tiltable chair back, comprising a device as claimed in any preceding claim.