This invention relates to a wire compensator for absorbing elongation of wires in a wire driving window regulator for raising and lowering a window glass of a motor car door or the like by means of wires.
In FIG. 1, there is shown a typical conventional window regulator which comprises a vertical guide rail 2, a carrier plate 63 mounted on this guide rail to be movable upward and downward and also firmly attached to a window glass (not shown), and a gearing device 64.
A wire 66 being wound round a drum 65 of the gearing device 64 and extending therefrom is led by guide rollers 67, 68 each mounted at the top and bottom of the guide rail 62, and is fastened at each end 66a, 66b of the top and bottom parts of the carrier plate 63 respectively. The wire 66 passes through tubes 69, 71 between the guide rail 62 and the gearing device 64, and the tubes 69, 71 are attached at each one end to the guide rail 62 by a holder 72, and also are connected at each another end to the gearing device 64 by a compression spring 73.
In this conventional window regulator 61 in which the drum 65 can be rotated in either normal and reverse directions to raise and lower the carrier plate 63 and the window glass, there is a possibility that repeatedly applying tensile loads to the wire 66 made of such as a metal wire causes a permanent elongation in the wire, and this elongation of the wire results in unsteady movement of the carrier plate 63 when raised and lowered.
In order to prevent the above problems, the window regulator 61 as illustrated in FIG. 1 is provided with a tension compensator 74 comprising the compression springs 73 at an end of an outer casing of the gearing device 64, and when elongation occurs in the wire 66, the compression springs 73 may expand to absorb the elongation of the wire 66.
There is also disclosed another example of such a conventional tension compensator in Japanese Patent Publication No. 46-3001 (see FIG. 4 in particular), which has the same characteristic features with the tension compensator 74 as described in the above.
FIG. 2 shows another window regulator according to the prior art, in which a wire 77 is wound round a drum 65 of a gearing device 76, passes through tubes 78, 79 and then is led by guide members 81, 82 each mounted at the top and bottom of the guide rail 62, and is finally fastened at ends 77a, 77b to the top and bottom of the carrier plate 63 respectively.
The tubes 78, 79 are secured at each one end to the guide members 81, 82 respectively, and bolts 83, 84 each connected to another end of the tubes 78, 79 are screwed onto threaded parts 85, 86 provided at the top and bottom of the gearing device 76.
When elongation occurs in the wire 77, by threading the bolts 83, 84 to substantially increase the route length of the tubes 78, 79 for guiding the wire 77, the elongation of the wire can be absorbed.
In the wire tension compensators as described in the above, there are problems such that arrangements of the wires within the outer casings of the gearing devices 64, 76 are so unnatural that it is heavy to operate the window regulators 61, 75, and that it becomes difficult to adjust tension of the wires 66, 77 according to locations for mounting the gearing devices 64, 76.