Patent GB-1535667-A (GB)
Title: Device for winding up a belt band or web
IPC: B60R22/44
Filed: 1977-04-28
Abstract: 1535667 Winding up seat belts J N EBERLE & CIE GmbH 28 April 1977 [28 April 1976 19 May 1976 9 Aug 1976 (2)] 17859/77 Heading A3V A wind-up device, Fig. 2, for a seat belt 1 and of the kind comprising a drive means (7), Fig. 1 (not shown) for winding the belt 1 onto a winding roller 4 is characterised by a spring element 2 that is windable with the belt into a common coil 6 on the roller 4, the unwound end of the spring element 2 being led away from the belt 1 to a separate source 8. The effect of the spring element 2 is to ensure that the tension in the belt 1 during the initial pull-out period is minimised and that the required tension in the belt is present only when the belt has been pulled out beyond a predetermined length. In Fig. 2 the spring 2 may be a scroll spring that is windable onto the roller 4 counter to its normal direction of curvature, so that the scroll springs tends to counter the wind-up effect of a power spring 7, the scroll spring 2 having a free end that extends away from the roller 4. When the belt 1 is fully wound onto the roller 4, the scroll spring 2 may be entirely within the convolutions of the belt 1. The curvature of the scroll spring 2 may vary along its length or the cross section of the spring may vary, for example by having a tapering width or by being formed with a longitudinally extending central slit of varying width. Fig. 6 shows how a housing 5 may have an upper compartment 12 in which the scroll spring 2 can coil freely, there being a wall element 16 that ensures that the free end 14 of the scroll spring 2 is guided up into the compartment 12 when the belt is unwound. An additional wall 13, is associated with the wall element 16 to form an aperture through which the seat belt 1 passes, the arrangement being such that when the seat belt 1 is fully unwound the seat belt passes through the aperture without being deflected by the aperture. Fig. 8 shows a modification in which the walls 13, 16 are jointly displaceable longitudinally such that the belt 1 can always pass through the aperture between the walls 13, 16 without being deflected by the aperture. Fig. 15 shows a modified arrangement in which there is an additional spring 44 attached to the core 4, the spring 44 being so coiled that when it is forced into its housing 42 on unwinding of the belt 1 it adds to the effect of the spring (7) that tends to wind up the belt 1 onto the roller 4. The spring 44 thus ensures that the belt 1 has its required tension only after a certain length has been unwound from the drum 4. Fig. 18 shows an embodiment similar to that in Fig. 15 except that the free end of the spring 44 has an aperture in which a pin 49 extends to prevent the spring 44 from entering the convolutions of the belt on the drum 4. When the seat belt commences to be wound up onto the drum by the power spring 7, the winding on the drum 4 increases in diameter until it causes an arm 50 to retract the pin 49 from the spring 44, whereupon the spring 44 enters the windings on the drum 4 and supplements the power of the spring 7 as described with reference to Fig. 15.