GB2272727A

GB2272727A - Interior mirror with ball joint

Info

Publication number: GB2272727A
Application number: GB9223535A
Authority: GB
Inventors: Michael Joseph Hammett; Peter John Whitehead
Original assignee: Britax Wingard Ltd
Current assignee: SMR Automotive Mirrors UK Ltd
Priority date: 1992-11-10
Filing date: 1992-11-10
Publication date: 1994-05-25
Also published as: GB9223535D0

Abstract

An interior mirror for a motor vehicle has its housing mounted on a tilt plate 20 which carries a boss 30 containing bore 32 having a lip which forms one part 34 of a socket for engaging with a part-spherical ball 14 secured to one end of a base stem 12. The other part of the socket is formed on a plug 36 which is slidable in the bore and biassed by a spring 40 so as to tend to reduce the effective diameter of the socket. <IMAGE>

Description

INTERIOR MIRROR This invention relates to an interior mirror for a motor vehicle of the type having a mirror glass mounted in a housing which contains a part-spherical socket for engaging with a part-spherical ball secured to one end of a base stem.

In known mirrors of this type, the part-spherical socket is formed of a moulded plastics material of sufficient resilience to allow a rigid ball to be pressed into it. The torque resisting angular movement of the housing relative to the stem is dependent both on the materials used and on the fit of the ball. It is therefore very difficult to control. In order to overcome this problem, it has been proposed to provide an adjustment screw for varying the effective size of the socket. This arrangement has the disadvantage that each mirror has to be adjusted individually during production.

The reflective element of a mirror of this type is commonly in the form of a prism with a reflective surface deposited on the second surface of the prism. By tilting the prism, a user can choose between viewing a bright image reflected from the second surface of the prism or a dim image reflected from the first surface of the prism, the latter option being used at night so as to avoid dazzle of the headlamps from following vehicles. The force resisting adjustment of the mirror on its ball joint is critical with this type of mirror. If the force is too high, the mirror dipping mechanism may be actuated inadvertently when adjusting the mirror angle. On the other hand, if the force is too low, the mirror housing orientation may be altered inadvertently when the dipping mechanism is operated.

It is an object of the present invention to provide an interior mirror in which the adjustment force can be accurately predetermined and can be maintained at a reasonably constant value over a wide range of temperatures.

According to the invention, in an interior mirror of the type described above, the socket is formed in two parts, which are arranged for linear movement relative to one another so as to vary the effective diameter of the socket in one direction and spring means are arranged to bias the two parts relative to one another so as to tend to reduce said effective diameter.

Preferably, means are provided for inhibiting relative angular movement of the two parts of the socket about an axis parallel to the direction of linear movement.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of an interior mirror in accordance with the invention; Figure 2 is an exploded view of part of the mirror shown in Figure 1; Figure 3 is a horizontal cross-sectional view of a tilt plate forming part of the mirror shown in Figure 1 before it gas been mounted on the base stem; Figure 4 is a cross-sectional view, similar to Figure 3, but after the tilt plate has been mounted on the stem; and Figure 5 is a cross-sectional view taken on the line 5-5 in Figure 4.

Figure 1 shows an interior mirror comprising a housing 10 mounted on a stem 12. The stem 12 has a ball 14 on its free end which engages in a socket in the housing 10. A lever 16 projects from the bottom of the housing 10 to permit actuation of a dipping mechanism so as to tilt a mirror prism (not shown) about a horizontal axis within the housing 10.

Referring to Figures 2 and 3, a tilt plate 20 is located within the housing 10. As in known mirrors, the tilt plate 20 has two holes 22 and 24 in which a pivot pin (not shown) is journalled, this pivot pin serving to attach the housing 10 to the tilt plate 20. The tilt plate 20 also has formations 26 and 28 which engage with complementary formations (not shown) on the tilt lever 16.

This type of tilt mechanism is well known and will not be described in further detail.

The tilt plate 20 includes a boss 30 containing a cylindrical bore 32 with a lip having a concave partspherical inner surface 34 on its outer end. A cylindrical plug 36 is slidable in the bore 32 and has a concave hemispherical surface 38 confronting the part-spherical surface 34.

A spring pin 40 is received in a transverse groove 42 in the end of the plug 36 opposite to the concave surface 38. The ends of the spring pin 40 are received in grooves 44, 46 in respective flanges 48 and 50 and under integrally formed stirrups 52 and 54 on the surface of the tilt plate 20 opposite to the boss 30. The pivot pin 40 both resists displacement of the plug 36 out of the bore 34 and prevents angular movement of the plug 36 about the axis of the bore 34.

Referring to Figures 4 and 5, when the ball 14 on the end of the stem 12 is forced past the lip formed by the concave surface 34 and into the spherical socket formed by the surfaces 34 and 38, the plug 36 is displaced outwardly of the bore 32, thereby bowing the spring 40. The spring 40 thus causes the plug 36 to exert a frictional force on the ball 14 which is substantially independent of both temperature and manufacturing tolerances.

As an alternative to the use of the engagement of the spring 40 in the groove 42 to resist angular movement of the plug 36, both the latter and the bore 32 may be of non-circular cross-section or may be provided with a spline and keyway.

Claims

1. An interior mirror for a motor vehicle of the type having a mirror glass mounted in a housing which contains a part-spherical socket for engaging with a part-spherical ball secured to one end of a base stem, wherein the socket is formed in two parts, which are arranged for linear movement relative to one another so as to vary the effective diameter of the socket in one direction and spring means are arranged to bias the two parts relative to one another so as to tend to reduce said effective diameter.

2. A mirror according to claim 1 or 2, wherein one of said two parts contains a through hole having a lip with a concave part-spherical inner surface on one end, and the other of said two parts comprises a plug slidably located in the bore 32 and having a concave hemispherical surface confronting the part-spherical surface on the lip.

3. A mirror according to claim 2, wherein said hole and plug are both of non-circular cross-section so as to inhibit relative angular movement therebetween.

4. A mirror according to claim 1 or 2, further comprising means for inhibiting relative angular movement of the two parts of the socket about an axis parallel to the direction of linear movement.

5. A mirror according to claim 4, wherein the means for inhibiting relative angular movement of the two parts of the socket comprises respective abutment surfaces on the two parts each of which is arranged to engage with the spring.

6. An interior mirror for a motor vehicle, substantially as hereinbefore described with reference to the accompanying drawings.