The invention relates to a rear view mirror for vehicles which is adjustable in two planes and in which the mirror support which holds the glass mirror is arranged within a mirror housing and coupled through a cruciform joint to the housing which accommodates the adjusting drive, an adjustment of the mirror support relative to the mirror housing being effected by the adjusting drive acting on the axis of said cruciform joint.
A rear view mirror for vehicles of this kind is known from German GM 82 17 325. In this known rear view mirror the adjustment of the mirror support is made through a pair of screw spindles operatively driven by the adjusting drive and of which one is in each case arranged in prolongation of one of the axes of the cruciform joint. These two axes of the cruciform joint are mutually rigidly connected at the point of intersection thereof, one axis being attached to the mirror support and the other being attached to the drive housing. However, it was found in practice that this constructional arrangement needed certain improvements.
In order to avoid vibrations of the mirror region which projects outwardly over the screw spindles these spindles must be sited as far out as possible; this entails a considerable spindle length and therefore also an unfortunately great constructional depth of the mirror housing which restricts the viewing range for the driver. Furthermore geometrical faults arise in the course of mirror adjustment because the cruciform joint axis which is secured to the stationary drive housing cannot follow the in- and out-displacements of the associated spindles in such a way that the prolongation of the axis will always pass through the center of the spindle head; this causes a wobbling movement for the associated spindle and therefore reduced functional efficiency for large adjusting angles. Furthermore, the provisions of proper seals at the spindle lead-through points in the drive housing requires substantial expense. Lastly, the spindle length limits the adjusting angle which is very unfavorable particularly in the case of interior mirrors.
It is the basic aim of the invention to provide a rear view mirror for vehicles which is no longer afflicted by these drawbacks. Starting with the initially described known rear view mirror for vehicles, the invention solves this problem by virtue of the fact that the cruciform joint axes:
(a) are both connected with the drive housing; PA1 (b) are operated direct by the adjusting drive, and PA1 (c) are relatively independently rotatable, one axis being attached to the mirror support and the other axis being attached to the mirror housing.
Due to this constructional arrangement the adjustment of the mirror in one plane is obtained by relative displacement of the unit comprising mirror support and mirror glass relative to the drive housing which is stationary during this movement and adjustment in the other plane is obtained by relative displacement of the unit comprising the drive housing, the mirror support and the glass mirror relative to the fixedly mounted mirror housing. In other words, adjustment of the mirror in the one plane has--primarily due to the relatively independent rotatability of the two cruciform joint axes--no effect whatsoever on the other plane so that no geometrical faults or errors can arise. The direct actuation of the joint axes by the adjusting drive eliminates the use of screw spindles and thus creates the precondition for shallow depth measurements and dispensation with sealing problems. Moreover, the joint axes of the cruciform joint may reach as far outwards from the drive housing as desired so that even very large mirrors may be supported in absolutely vibration-free manner. The adjusting angle of the rear view mirror according to the invention is virtually unrestricted.
According to another essential feature of the invention the axes of the cruciform joint are arranged in a plane but are not materially extended within the drive housing. This embodiment is one of several options for rendering the two axes of the joint relatively independently rotatable and would seem to be the most elegant constructional solution.
It was found to be of advantage if each of the two axes of the cruciform joint comprises an axle stub projecting outwardly over the drive housing and carrying a coupling element for operatively connecting the drive housing to the mirror support or to the mirror housing. This arrangement affords a very simple assembly and dismantling operation for the rear view mirror according to the invention and enables an uncomplicated exchange of the adjusting drive.
According to a further development of the invention each driven axis is associated with a slipping clutch which on the one hand fulfills the function of an overload safety device while on the other hand it creates the option of manual rear view mirror adjustment which may become necessary if the adjusting drive fails or the vehicle electrical system malfunctions.