GB2212555A

GB2212555A - Clamping pivot

Info

Publication number: GB2212555A
Application number: GB8726888A
Authority: GB
Inventors: David Richard Osborn; Christopher John Dearman
Original assignee: Britax Restmor Ltd
Current assignee: Britax Child Safety Ltd
Priority date: 1987-11-17
Filing date: 1987-11-17
Publication date: 1989-07-26
Anticipated expiration: 2007-11-17
Also published as: GB8726888D0; GB2212555B; DE3838925A1

Description

p 4 CLAMPING PIVOT r 22125 j This invention relates to a clamping pivot

joint whereby two members may be coupled to one another for relative angular movement about a pivot axis and secured at a selective orientation relative to one another.

A known pivot joint of this type comprises a rod forming the pivot axis and having a screw-threaded formation at one end and means providing a shoulder at its other end, a first coupling element mounted on the rod and having at least one detent formation, a second coupling element secured fast with the second member and journaled on the rod so that a complementary formation thereon is engageable with the detent formation on the first coupling element, a manually rotatable control element journaled on the rod on the opposite side of the second coupling element to the first coupling element and a nut engaging on the screw-threaded formation of the rod to retain the first and second coupling elements and the control element thereon, mutually confronting surfaces of the second coupling element and the control element having cam-and-follower formations thereon arranged so that angular movement of the control element relative to the second coupling element causes axial movement of the first coupling element along the rod to bring the complementary formation thereon into engagement with the detent formation on the first coupling element, thereby to inhibit relative angular movement between the first and second coupling elements.

The extent to which the nut is screwed on to the rod determines the range of axial movement which can be produced by angular movement of the control element. if the nut is screwed on to the rod to an insufficient extent, thecomplementary formation on the second control member may not be brought into sufficiently reliable locking engagement with the detent formation on the first control member. - It is therefore important for the nut to remain in its preset position. However, frictional engagement between the control element and the nut may result in the nut being partially unscrewed from the rod to such an extent that locking engagement is no longer possible. It is an object of the invention to provide a clamping pivot joint which is not subject to this disadvantage.

According to the-invention, in a clamping pivot joint of the foregoing type, a washer is disposed between the nut and the element with which it engages, the washer being keyed to the rod so as to be axially moveable therealong but restrained against rotation relative thereto.

The effect of this arrangement is that any tendency -for rotation of the control element to cause angular movement of the washer has an equal effect on the rod and vice versa, with the result that there is no possibility of'such rotation causing angular movement of the nut relative to the rod.

In one form of the invention, the washer comprises a flange formed integrally with a hollow cylindrical stem through which the rod projects and which itself projects through the openings in the various elements, the opposite end of the stem being keyed, directly or indirectly, to the rod.

The means for providing a shoulder at the opposite end of the rod to the screw-threaded formation may comprise a head formed integrally with the rod.

Alternatively, the rod may have screw-threaded formation at both ends, in which case either the rod may engage in a tapped hole in the element at the opposite end of the rod to the nut, such element itself providing the shoulder or the means for providing the shoulder may be a second nut.

An embodiment of the invention will now be 1 k 1 1 described, by. way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a pushchair having a clamping pivot joint in accordance with the 5 invention; Figure 2 is an exploded perspective view of a clamping pivot joint for connecting the seat body of a pushchair to the frame thereof, seen from one side of the pushchair; Figure 3 is an exploded partially broken-away perspective view of the clamping pivot joint shown in Figure 2 but seen from a point on a longitudinal vertical plane of symmetry of the pushchair. 1 Referring first to Figure 1, a pushchair comprises a seat body 10 connected to side members 12 and 14 of the-frame of the pushchair by respective clamping pivot joints 16 and 18. The pivot joints 16 and 18 permit the seat body 10 to pivot between the position illustrated, in which the seat portion 20 thereof is substantially horizontal, and a reclined position in which the seat portion 20 and the backrest portion 22 are disposed at approximately equal, but opposite, angles to the horizontal. The periphery of the seat body 10 is surrounded by a tubular member 28. The rest of the pushchair forms no part of the invention and will not be described further.

Figures 2 and 3 show the pivot joint 16, which is substantially identical to the pivot joint 18. The pivot joint 16 has a disc-like first coupling element 30 with a tubular formation 32 extending along its edge, whereby it is secured rigidly to the tubular member 28. A second coupling element 34, similar to the coupling element 30, has a tubular formation 36 whereby it is secured to the side member 12 of the frame in alignment with the first coupling element 30. Each of the coupling elements 30 and 34 has a central hole for accommodating a bolt 38 with its axis perpendicular to the longitudinal axes of the tubular members 12 and 28. The end of the hole 40 in the first coupling element 30 is of square cross-section dimensioned to receive a square cross-section formation 41 adjacent to the head 43 of the bolt 38. The other end of the hole 40 is of hexagonal cross-section and is larger than the portion of square cross-section and serves a purpose to.be explained hereinafter. The central hole 42 in the second coupling 10 element 34 is of circular cross-section.

The mutually confronting surfaces of the coupling elements 30 and 34 carry respective sets of detent formations 44 and 46 circumferentially spaced around the central holes 40 and 42 respectively and so arranged that if the two coupling elements 30 and 34 are urged into engagement with one another, relative -angular movement about the bolt 38 is prevented while, if they are allowed to move apart from one another, such angular movement is possible.

The second coupling element 34 has a circular recess 52 coaxial with its central hole 42 on the side opposite to the first coupling element 30. An annular flange 54 projects from the inner end of the recess 52 and is spaced radially inwardly from the side wall thereof. on its free edge, the flange 54 has three symmetrically-located cam profiles each of which consists of a ramp portion 56 and a.flat portion 58 located at the end of the ramp portion 56 further from the base of the recess 52. Each of the three cam formations is 30 separated from its neighbour by a projection 60.

A control knob 62 has a central hole 64, through which the bolt 38 projects, and an annular skirt 66 dimensioned to project into the recess 52 radially outwardly of the flange 54. Inside the skirt 66, the control knob also has three uniformly-spaced cam followers 68, 70 and 72, each of which engages with a i respective cam formation on the flange 54. A springloaded detent 74 projects radially outwardly from the skirt 66 and is engageable in a slot 76 in the side of the recess 52 when the cam followers 68, 70 and 72 are in engagement with the flat portions 58 of their respective cam profiles.

on the opposite side to the skirt 66, the control knob 62 has a cylindrical recess 80. A cylindrical sleeve 82, having a circular flange 84 on one end and a hexagonal formation 86 on the other projects through the holes 64 and 42 in the control knob 62 and the second coupling element 34 respectively, and the hexagonal formation 86-engages in the hexagonal part of the hole 40 in the first coupling element 30, the flange 84 being received in the recess 80 in the control knob 62. The engagement between the hexagonal formation 86 and the hole 40 prevents rotation of the flange 84 relative to the first coupling element 30 which is itself nonrotatably coupled to the bolt 38 by the square formation 41 thereon. Consequently, although the flange 84 can move axially relative to the bolt 38, rotation relative thereto is prevented. The assembly is held together by a nut 88 which engages on a screw thread 90 formed on the opposite end of the bolt 38 to its head 43. Since it will usually be convenient to form the sleeve 82 and flange 84 as a plastics moulding and the nut 88 of metal, a metal washer 92 is preferably located between the nut 88 and the flange 84 although this is not essential. 30 A cap 94 has a hexagonal recess 96 for receiving the nut 88 on one side and a transverse slot 98 on the other. The slot 98 is wide enough to receive a coin and thus permits adjustment of the nut 88 without special tools. The cap 94 also has a flange 100. An annular retaining cap 102, which is dimensioned to be an interference fit in the recess 80, engages with the 1 flange 100 to keep the cap 94 in place.

In use, the nut 88 is tightened so that, when the cam followers 68, 70 and 72 are in engagement with the flat portions 58 of their respective cams, the detent formations 44 and 46 on the two adjustment elements 30 and 34 are held firmly in engagement with one another and relative angular movement between the tubular members 12 and 28 is prevented. If the spring loaded detent 74 is then disengaged from the slot 76 and the knob 62 rotated in the anti-clockwise direction, as viewed in Figure 2, the cam followers 68, 70 and 72 move along the ramp portions 56 of their respective cams, allowing the second coupling element 34 to move axially along the bolt 38 away from the first coupling element 30, thus disengaging the detent formations 44 and 46 from one another and allowing the angle between the tubular members 12 and 28 to be varied, thereby varying the angle between the chair body 10 and the pushchair frame. The knob 62 can then be turned in the clockwise direction to re-engage the detent formations 44 and 46, thus locking the mechanism in its new position. Since the flange 84 is, at all times held stationary relative to the bulk 38, there is no possibility of angular movement of the control knobs 62 being transmitted to-the nut 88, causing the latter to be loosened.

Instead of providing a separate retaining cap 102, the cap 94 may itself be an interference fit on the nut 88 and a loose fit in the recess 80.

As an alternative to coupling the bolt to the first coupling element by means of the square crosssection formation 41, and the sleeve 82 to the first coupling element 30 by the formation 86 of hexagonal cross-section, the stem 82 may be directly coupled to the bolt 38. It is not essential for relative angular movement between the bolt 38 and the first coupling element 30 to be prevented. However, prevention of such d 1 1 1 relative movement is preferable in order to avoid the need to provide separate means for holding the bolt 38 stationary while the position of the nut 88 thereon is being adjusted. A further alternative is to key the 5 bolt 38 and sleeve 82 to the second adjustment element 34 and allow them to rotate relative to the first adjustment element 30. Yet another possibility within the scope of the invention is to provide an opening with a square cross- section outer part and a hexagonal cross-section inner part in the control knob 62 and to insert the bolt 38 from this end. The flange 84 on the disk 82 then engages with the first coupling element 30. This arrangement has the advantage that it is not necessary for the slot 98 or other means for adjusting the nut 88 to be visible on the outer face of the knob 62.

The invention may find application wherever it is desired to selectively restrain relative movement between two pivotally coupled members.

1

Claims

1. A clamping pivot joint for coupling two members to one another for relative- angular-movement about a pivot axis and securing said two members at a selective orientation relative to one another, comprising a rod forming the pivot axis and having a screw-threaded formation at one end and means providing a shoulder at its other end, a first coupling element mounted on the rod and having at least one detent formation, a second coupling element secured fast with the second member and journaled on the rod so that a complementary formation thereon is engageable with the detent formation on the first coupling element, a manually rotatable control element journaled on the rod on the opposite side of the second coupling element to the first coupling element and a nut engaging on the screw-threaded formation of the rod to retain the first and second coupling elements and the control element thereon, mutually confronting surfaces of the second coupling element and the control element having cam-and-follower formations thereon arranged so that angular movement of the control element relative to the second coupling element causes axial movement of the first coupling element along the rod to bring the complementary formation thereon into engagement with the detent formation on the first coupling element, thereby to inhibit relative angular movement between the first and second coupling elements, wherein a washer is disposed between the nut and the element with which it engages, the washer being keyed to the rod so as to be axially moveable therealong but restrained against rotation relative thereto.

2. A clamping pivot joint according to claim 1, wherein the washer comprises a flange formed integrally with a hollow cylindrical stem through which the rod projects and which itself projects through the openings 1 in the various elements, the opposite end of the stem being keyed, directly or indirectly, to the rod.

3. A clamping pivot joint according to claim 2, wherein the the stem is keyed to the first coupling element and the first coupling element is keyed to the bolt.

4. A clamping pivot joint according to claim 2, wherein the the stem is keyed to the control element and the control element is keyed to the bolt.

5. A clamping pivot joint according to any preceding claim, wherein the means for providing a shoulder at the opposite end of the rod to the screw-threaded formation comprises a head formed integrally with the rod.

6. A clamping pivot joint according to any preceding 15 claim, wherein the rod has screw-threaded formations at both ends and engages in a tapped hole in the element at the opposite end of the rod to the nut.

7. A clamping pivot joint according to any preceding claim, wherein the rod has screw-threaded formations at both ends and engages-in a second nut.

8. A clamping pivot joint for coupling two members to one another for relative angular movement about a pivot axis and securing said two members at a selective orientation relative to one another, substantialy as hereinbefore described with reference to the accompnying drawings.

Published 1989 atThe Patent Office, State House, 56,171 High Holborn, London WC1R4TF. Further copies maybe obtainedfrom The PatentOffice.

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