GB2309739A - A ball joint mounting - Google Patents

Abstract

A ball and socket joint for mounting a rear view mirror of a vehicle, consists of a ball 30, a retaining socket 20 and a base 10 which has a tapered bore 11. The retaining socket is formed as a longitudinally split sleeve having an outer conical surface 21 and an inner surface of part spherical section 22. The ball is held captive in the retaining socket by the interengagement of the spherical surfaces. The retaining socket is then pressed into the base so that the surfaces 11 and 21 mate. A peripheral flange 26 on the socket may engage a recess 13, formed in the inner surface of the base, to prevent the disengagement of the socket. The retaining surface 22 of the socket may alternatively be two opposed conical surfaces and the socket may be formed of two identical pieces. * small Greek theta * is preferably 2{.

Description

RALL JOINT MOUNTING This invention relates to a mount for a vehicle interior mirror, where the load on the mount is only a few ounces. Typical examples would be rear view mirrors or elements of a forward viewing system.

It is normal practice to mount such mirrors in adjustable mountings, typically a plastic ball-joint. The tightness of these ball-joints is usually adjusted by compressing some part of the socket with a screw thread arrangement, it may also be necessary to allow for creep of the plastic with time. Although these threaded arrangements work well, they either require extra metal components or, if the thread be in the plastic, cause complications in the moulding process.

The invention overcomes the above problems and achieves its objectives without the need of threaded elements. More particularly, the invention is defined by the independent claims, to which reference should now be made.

The invention will now be described by way of example and with reference to the attached drawings.

Fig.1 shows a section through a ball-joint of the type that is the subject of the invention.

Fig.2 is a representation of the retained socket.

Fig.3 shows a mirror mount incorporating the invention.

In a particular embodiment, the invention comprises an adjustable mirror mount, having a base 10 which is fixed to a suitable point in the interior of the vehicle, a retained socket 20 and the ball 30 which is rigidly attached or integral with the articulated member 40.

The base 10 has a tapered bore 11, the surface of which is part of a cone of apex angle 28. The retained socket 20 is in the form of a split sleeve, having an outer conical surface 21 formed from a cone of apex angle 26. The inner surface has a spherical section 22 of radius R and sections 23 and 24, which may be conical or cylindrical of radius r, r being less than R. A rim 25 is provided to assist in assembly.

The ball has a radius close to R, but, as it has limited angular movement, those parts of the surface which do not engage with section 22 at any part of the movement need not be spherical.

An unused spherical cap may be reduced to a plane surface.

To assemble the joint, the retained socket 20 is sprung over the ball 30 until both spherical surfaces are engaged and the ball is captive. The retained socket 20 is then pressed into the baselO so that the surfaces 11 and 21 mate. The tightness of the joint is increased as the split sleeve form of the retained socket is pressed further into the taper bore 11. It will be appreciated that the retained socket 20 could be made in two identical sections rather than a single split item.

It is not essential for the operation of the joint that the surface 22 should be spherical. Although a spherical surface is preferable, it might be replaced, for example, by two opposed conical surfaces to trap the ball.

In practice, it is found that, for the joint to remain assembled, an angle e of 20 is satisfactory if the components be made of acetal resin. Further, the retained socket 20 springs satisfactorily if R = 8mm and (R-r) = 0.5mm, the thickness then varies between imm and 1.5mm. Sufficient adjustment is provided if the gap in the retained socket be lmm.

Fig.3 shows a mirror mount in which the weight of the mirror and ball 30 acts towards the base 10, so adding to the compression of the retained socket 20. Where it is required to suspend the mirror, the taper may be in the opposite sense, the bore being greater at the base surface 12.

If conical surfaces be used for the faces 11 and 21, it is possible, by repeated swivelling, to disengage the retained socket from the base. The possibility may be reduced by a circumferential bead 26 on the retained socket 20 locating in an elongated circumferential depression 13 in the base 10. The bead 26 is an interference fit in the base 10 until the conical surfaces engage.

The bead 26 and the depression 13 do not need to utilise the entire circumference and the bead 26 could be incorporated into the rim 25.

Preferably, the components are made by injection moulding.

It is not essential that the same plastic be used for all the components and desirable properties may be conferred by using dissimilar properties.

Claims (6)

1. An adjustable articulated mount comprising a ball and socket joint whose ball unit is held in a socket which is a push fit into a base unit.

2. A device according to Claim 1 wherein the socket unit is split in a direction substantially parallel to its axis.

3. A device according to Claim 1 or 2 wherein the mating surfaces between the socket unit and the base unit are cylindrical.

4. A device according to Claim 1 or 2 wherein the mating surfaces between the socket unit and the base unit are substantially conical.

5. A device according to any of the above claims wherein the socket unit is latched in the base unit by a bead on its outer face locating in a depression in the inner face of the base unit.

6. A joint substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.