GB783651A - Improvements in or relating to window wiping equipment - Google Patents

Abstract

783,651. Windscreen cleaners. BOSCH GES., R. Aug. 5, 1955 [Aug. 7, 1954; July 4, 1955], No. 22542/55. Class 138(1). [Also in Group XXIV] In window wiping equipment for driving an oscillatable wiper blade or blades including an electric driving motor and reduction gearing, so that a reduction of the torque required to drive the blade or blades occurs in the region of each reversing or terminal position of the blade or blades, means are provided which during operation of the equipment tend to prevent any substantial increase in motor speed which would otherwise result from the torque reduction. As shown in Figs. 2 and 3, the electric motor, in a housing 10, drives a pinion 27 meshing with a gear wheel 26. A gear wheel 25 integral with the wheel 26 meshes with a gear wheel 8 secured to a shaft 7 connected through a linkage with the windscreen wiper arm or arms. Raised brake cams 11 are provided on the wheel 8, each comprising a gradual inclined portion 14, an even portion 13 and a steeply inclined portion 12. The cams 11 can engage, in turn, a brake pad 16 carried by a spring 15 secured to the gear housing 9. The cams are arranged to engage the brake pad as the wiper blades move towards their terminal positions on the windscreen, and when the torque on the motor is reduced and thus prevent the latter from increasing its speed. In the embodiment shown in Fig. 8, the gears 26, 25 are axially slidable on a shaft 30 against the urge of a spring 31 and the gear pair 25, 8 have helical teeth. When the electric motor 29 is at rest the spring 31 urges the gear 26 against a brake pad 32 but when the motor is running and the torque increases, axial thrust between the gears 25, 8 cause the gears 25, 26 to rise away from the pad 32 against the spring 31. As the torque on the motor is reduced when the wiper blades move towards their terminal positions, the spring 31 overcomes the axial thrust and applies the brake. The gear pair 26, 27 may have helical teeth in which case the fluctuations in the motor load are more rapidly corrected. If desired the gear pair 25, 8 may have straight teeth and the pair 26, 27 helical teeth, in which case the brake 32 is disposed above the gear 26 and the gears 25, 26 are urged upwardly by a helical spring. Instead of the mechanical brakes described, braking may be effected electrically. In the case of a compound-wound D.C. electric motor, a resistance is connected by a cam actuated switch, in parallel with the armature, to reduce the armature current, as described with reference to Fig. 6 (not shown). In the case of a shunt-wound D.C. electric motor, a resistance is insertable in series with the armature by a cam-operated switch as described with reference to Fig. 7 (not shown).