GB2031058A

GB2031058A - Lockable Stays

Info

Publication number: GB2031058A
Application number: GB7916677A
Authority: GB
Original assignee: FRENCH ENG Ltd J
Current assignee: FRENCH ENG Ltd J
Priority date: 1978-05-24
Filing date: 1979-05-14
Publication date: 1980-04-16
Also published as: GB2031058B

Abstract

A stay mechanism for locking one component in a selected position relative to another component, for example for locking a pivotal chair back in a selected angular position relative to the seat part comprises two toothed members e.g. an externally threaded member (30) secured to one of the two components and an internally threaded member (32) secured to the other of the two components. One of the screw- threads is machined away over part of its circumference to enable the member (30) to be displaced laterally between positions in which it is engaged with and disengaged from the member (32), this lateral movement being effected as shown by the means of a cam (34). When the two members are disengaged, one of the members can be moved into a selected axial position whereupon the cam (34) is operated to displace the member (30) laterally into engagement with the member (32) so as to lock the members together. <IMAGE>

Description

SPECIFICATION Adjuster Mechanisms The present invention relates to adjuster mechanisms for locking one component in a selected position relative to another component, and more particularly but not exclusively to adjuster mechanisms for locking a pivotal back part of a chair in a selected angular position relative to a seat part of the chair.

According to the present invention, there is provided a mechanism for adjusting the relative position of two components, said mechanism comprising first and second relatively movable members each arranged for connection to a respective one of the two components, each of said members having a toothed portion extending in the direction of the axis of relative movement of the two members, the toothed portion of one of said members being movable relative to the other member in a direction transversely to said axis, between a position in which the toothed portion of the said one member is disengaged from the toothed portion of the other member whereby to permit relative movement between said members in the direction of said axis, and a position in which the toothed portions of the two members are in engagement to secure the two members in a selected position against such relative movement, and control means for effecting movement of the said one member from one to the other of said positions.

According to the invention, there is further provided a mechanism for adjusting the relative position of two components, said mechanism comprising first and second telescopically movable members each arranged for connection to a respective one of the two components, an internal screw-thread movable with one of said members, an external screw-thread movable with the other of said members and surrounded by the internal screw-thread, said screw-threads extending along the axis of relative movement of said members and being such that one of said threads can move laterally between a position in which it is free from engagement with the other thread whereby to permit relative movement between the two members, and a position in which it is engaged with the other thread so that the two members are secured by the interengaging threads against relative movement, spring means applying a bias in a sense to move the said one thread into one of said positions, and cam means mounted for pivotal movement about the axis of relative movement of the two members to move the said one thread from the said one position into the other position against the bias of the spring means.

Further according to the invention, there is provided a mechanism for adjusting the relative position of two components, said mechanism comprising an internally screw-threaded member movable with one of said components, an externally screw-threaded member movable with the other of said components and locatable within the internally screw-threaded member, said members being relatively movable in the axial direction of the screw-threads and said screwthreads being such that one of said members can move laterally between a position in which its thread is free from engagement with the thread of the other member whereby to permit relative axial movement between the two members, and a position in which its thread is engaged with the thread of the other member so that the two members are secured by the interengaging threads against relative axial movement, said one member being biased to move into one of said positions, and cam means mounted on the other member to move the said one member from the said one position into the other position against the bias.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a side elevation of an adjuster mechanism according to the present invention; Figure 2 is a cross-section through the mechanism, the left-hand part of the section being taken on line X-X of Figure 1, and the right-hand part of the section being taken on line Y-Y of Figure 1; Figure 3 is a side elevation of another embodiment of an adjuster mechanism in accordance with the invention; and Figure 4 is a sectional end elevation of the mechanism of Figure 3.

The mechanism shown in Figures 1 and 2, comprises an outer tube 2 which is attachable by means (not shown) to one component, for example the frame of a seat part of a chair, and a tubular slide member 4 telescopically mounted within the outer tube and which is attachable by means (not shown) to another component, for example the frame of a pivotal back of the chair, which is movable into a selected one of a series of discrete positions relative to the first component.

An elongate cylindrical nut 6 is a press fit within the end portion of the outer tube 2 remote from the slide member 4, and projects outwardly from that end of the tube 2. The nut 6 receives an axially-extending screw-threaded rod 8 the thread of which is of the same pitch diameter as that of the nut. The inner end of the rod 8 is attached by means of a pin 10 to the slide member 4 so that the slide member 4 and rod 8 can move axially as a unit. The nut 6 and the screw-threaded rod 8 form, in effect, toothed portions carried by the tube 2 and the slide member 4 respectively.

Over approximately half of its circumference (as shown, the left-hand half in Figure 2), the screw-thread of the nut 6 is machined away, and when the screw-threaded rod 8 is displaced laterally to the left as viewed in Figure 2, the screw-thread of the rod 8 will move out of engagement with the remaining screw-thread on the nut 6 with the result that the assembly formed by the rod 8 and slide member 4 are freed to move axially relative to the assembly formed by the nut 6 and the outer tube 2.

The nut 6 is provided with two radially-directed lateral bores 12. The two bores are diametricallyopposed but are offset along the axis of the nut 6.

A bearing ball 14 having a diameter approximately equal to the wall thickness of the nut 6 is located in each of the bores 1 2. The righthand bore 12 shown in Figure 2 is aligned with the bore of a bush 1 6 inset into the wall of the outer tube 2 so as to project laterally from the outer tube 2. A compression spring 1 8 housed in the bush 1 6 is interposed between the ball 14 in the right-hand bore 12, and a screw cap 20 screwed into the outer end portion of the bush 16, and acts to apply a bias which urges the associated ball 14 and thus the rod 8 laterally towards the left and thus towards the non-screwthreaded part of the nut 6.This movement of the rod 8 is normally resisted by the opposing ball 14 which engages an inner annular surface of a camforming collar 22 mounted for rotation on the projecting portion of the nut 4 and located axially between the end of the tube 2 and a circlip 24 on the end of the nut 6. The inner surface of the collar 22 is concentric with the nut 6 and is formed with a part-spherical depression 22a.

When it is required to move the assembly of the rod 8 and slide member 4, relative to the assembly of the nut 6 and tube 2, the collar 22 is rotated manually until the depression 22a is aligned with the left-hand ball 14. This ball will then move into the depression and the rod 8 will move to the left under the bias of the spring 18, and, therefore, out of engagement with the threaded portion of the nut. The rod 8 is now free to move axially in the nut 6 to enable the required adjustment to be made in the axial position of the slide member 4 relative to the tube 2.When the desired relative position between these members has been attained, the collar 22 is rotated to move the depression 22a away from the left-hand ball 14 and thereby this ball and the rod 8 are displaced laterally towards the right so that the rod 8 is returned into engagement with the screw-threaded portion of the nut 6 and thereby the rod 8 and the slide member 4 are locked in their adjusted positions.

The mechanism shown in Figures 3 and 4 comprises a threaded stud 30 which passes through a block 32 which, in the embodiment shown, is of rectangular form. The block 32 is provided with a threaded bore which receives the stud 30, but most of the screw-thread has been machined away around its circumference so that only a portion of the original screw-thread remains. As shown, the original bore has been machined away to form an approximately rectangular passage 33 through the block with only about one fifth of the original screw-thread remaining.

A bolt 34 is slidably mounted in the block 32 for movement in a direction transversely with respect to the stud 30. The bolt 32 passes through the rectangular passage so as to lie adjacent a side of the passage opposite to the remaining portion of the original screw-thread.

The stud 30 is located within the passage between the bolt 34 and the remaining screwthread with a flat being machined along the bottom of the stud, and this flat rests on the bolt 34.

A portion 34a of the bolt shank is machined away to a reduced diameter, and when the bolt 34 is slid transversely relatively to the stud 30 into a position in which the flat of the stud 30 is seated within the reduced-diameter portion 34a (as shown in Figure 4), the thread of the stud 30 will be located out of engagement with the threaded side of the passage 33 in the block 32 to enable the stud 30 to be moved axially relative to the block 32. When the selected axial position has been reached, the bolt 34 is moved axially so that the flat of the stud 30 moves out of the reduced diameter portion 34e of the bolt shank and is pushed transversely by the bolt shank into engagement with the thread in the passage 33 so that the stud and the block are locked against relative axial movement.The shank of the bolt 34 with its reduced diameter portion 34a in effect forms a cam which is movable rectilinearly in order to move the stud between its engaged and disengaged positions.

The sliding movements of the bolt 34 are preferably effected by means of the handle 36 screwed onto one end of the bolt, with a spring 38 being interposed between the end of the handle and a side of the block 32 so as to bias axially the bolt 34 into a position in which it locks the stud 30 in engagement with the block 32, the stud 30 being disengaged from the block 32 simply by pressing the handle 36 against the bias of the spring 38 so that the stud 32 falls into the reduced-diameter portion 34a of the bolt 34.

Similarly to the first embodiment, the mechanism of Figures 3 and 4 may also be incorporated in a chair having a pivotal back so as to lock the back in a selected one of a series of discrete angular positions. For this purpose, the stud 30 may be connected to the frame of the pivotal back part, and the block 32 to the frame of the seat part of the chair.

Although the mechanism described is particularly suitable for use in adjusting the inclination of a seat back part, it may also be used for other purposes in which it is required to lock one component in a selected position relative to another component.

Claims

1. A mechanism for adjusting the relative position of two components, said mechanism comprising first and second relatively movable members each arranged for connection to a respective one of the two components, each of said members having a toothed portion extending in the direction of the axis of relative movement of the two members, the toothed portion of one of said members being movable relative to the other member in a direction transversely to said axis, between a position in which the toothed portion of the said one member is disengaged from the toothed portion of the other member whereby to permit relative movement between said members in the direction of said axis, and a position in which the toothed portions of the two members are in engagement to secure the two members in a selected position against such relative movement, and control means for effecting movement of the said one member from one to the other of said positions.

2. A mechanism according to claim 1, wherein each of said toothed portions is defined by a screw-thread.

3. A mechanism according to claim 2, wherein the two toothed portions are respectively defined by an internal and external screw-thread of the same pitch diameter, one of said threads being removed over part of its circumference to permit relative movement of the two threads transversely of the axis of the threads between said engaged and disengaged positions.

4. A mechanism according to any one of claims 1 to 3, wherein said control means comprises cam means mounted for pivotal movement.

5. A mechanism according to any one of claims 1 to 3, wherein said control means comprises cam means mounted for rectilinear movement.

6. A mechanism according to any one of claims 1 to 5, wherein the said one member is biased to move into its disengaged position.

7. A mechanism according to any one of claims 1 to 4, wherein the said one member is biased resiliently to move -into its disengaged position.

8. A mechanism for adjusting the relative position of two components, said mechanism comprising first and second telescopically movable members each arranged for connection to a respective one of the two components, an internal screw-thread movable with one of said members, an external screw-thread movable with the other of said members and surrounded by the internal screw-thread, said screw-threads extending along the axis of relative movement of said members and being such that one of said threads can move laterally between a position in which it is free from engagement with the other - thread whereby to permit relative movement between the two members, and a position in which it is engaged with the other thread so that the two members are secured by the interengaging threads against relative movement, spring means applying a bias in a sense to move the said one thread into one of said positions, and cam means mounted for pivotal movement about the axis of relative movement of the two members to move the said one thread from the said one position into the other position against the bias of the spring means.

9. A mechanism according to claim 8, wherein the external thread is formed on a rod which is movable axially with the said other member and which is movable laterally with respect to the internal screw-thread, the spring biases the said rod laterally via a ball which engages one side of the rod, and the cam acts on the rod via a ball which engages the opposite side of the rod.

10. A mechanism according to claim 9, wherein the cam is formed by a rotary collar, the ball associated with the cam is located within the inner annular surface of the collar and is held against rotation with the collar, and the said surface of the collar includes at least one depression which can be positioned to receive the ball upon rotation of the collar whereby when the depression is so positioned, the spring can act to move the rod laterally to one side, and when the collar is rotated to move the depression away from the ball, the ball is moved out of the depression and forces the rod laterally to the other side against the spring bias.

11. A mechanism according to claim 10, wherein the internal screw-thread is formed by the threaded surface of a nut carried by the said one member, the collar rotatably surrounds the nut, and the ball associated with the collar is located within a radial passage in the nut.

1 2. A mechanism for adjusting the relative positions of two components, said mechanism comprising an internally screw-threaded member movable with one of said components, an externally screw-threaded member movable with the other of said components and locatable within the internally screw-threaded member, said members being relatively movable in the axial direction of the screw-threads and said screwthreads being such that one of said members can move laterally between a position in which its thread is free from engagement with the thread of the other member whereby to permit relative axial movement between the two members, and a position in which its thread is engaged with the thread of the other member so that the two members are secured by the interengaging threads against relative axial movement, said one member being biased to move into one of said positions, and cam means mounted on the other member to move the said one member from the said one position into the other position against the bias.

13. A mechanism according to claim 12, wherein the two threads are of the same pitch size, and at least one of the threads is machined away over part of its circumference to permit the lateral movement of the said one member between its engaged and disengaged positions.

14. A mechanism according to claim 12 or claim 13, wherein the cam is mounted on the said one member for rectilinear movement and is biased into a position in which the said one member is held in its engaged position.

15. A mechanism according to claim 14, wherein the said one member is gravity-biased into its disengaged position.

1 6. A mechanism substantially as hereinbefore described with reference to Figures 1 and 2, or 3 and 4 of the accompanying drawings.