Patent GB-736064-A (GB)
Title: Improvements in or relating to a windshield wiper
IPC: B60S1/08
Filed: 1953-10-26
Abstract: 736,064. Control of D.C. motors; fluid actuation of switches; mechanical switches. TRICO PRODUCTS CORPORATION. Oct. 26, 1953 [Oct. 27, 1952], No. 29575/53. Classes 38 (3) and 38 (5). [Also in Group XXIII] Relates to the control of an electric motor driving a windscreen wiper installation (see Group XXIII) and to manual and automatic switches therefor. The electric motor 8, Fig. 9, drives a worm and two worm wheels connected respectively to two spaced wipers, through rocker arms and links in known manner. One of the rocker arms is provided with cam projection, which, when the rocker arm is in a position corresponding to the parked position of the wipers, actuates a switch 26, described with reference to Fig. 3 (not shown), to break the motor circuit. The circuit, Fig. 9, is controlled by a four-position manual switch 22. In the first position contacts A1, B1, C1 are bridged by the contact 23 and the motor 8 then only operates if the parking switch 26 is closed. Consequently the motor moves the wipers to the parked position and is de-energized when the switch 26 is automatically opened. In the second position, the contact 23 bridges contacts A2, B2, C2 and the motor 8 is connected through lines 21, 20 to run at its fastest speed. In the third position, the contacts A3, B3, D3 are bridged and a resistor 35 is then inserted in the circuit of the motor armature 16<SP>1</SP> so that the motor runs at a reduced speed. In the fourth position, which corresponds to automatic control, the contacts A4, B4, C4 and D4 are bridged. The resistor 35 is still in the armature circuit but may be short-circuited by a switch 38 responsive to the suction of the engine intake manifold. At high engine speeds when the motor is low the switch 38 short-circuits the resistor. The switch 38 may alternatively be operated by a centrifugal device mounted on the vehicle generator shaft as described with reference to Fig. 10 (not shown), or by continued depression of the vehicle accelerator pedal as described with reference to Fig. 11 (not shown). In both alternatives, the switch 38 is arranged to close when the engine is running at high speeds. Other vehicle controls may be used to actuate the switch 38 or it may be operated by an inertia actuated pendulum. The resistor may alternatively be arranged in the motor field 16 in the case of the shunt wound motor. If the motor is compound-wound, speed regulation may be achieved by alternate use of only the series field or the combined series and shunt fields. The manual control switch 22, Fig. 7, comprises chamber 18 the interior sides of which have fitted respectively thereto, the sets of contacts A, B, C, D, shown in Fig. 9. Four switch blades 23, all connected together (see Fig. 8), are mounted on a shank 33, slidable by a knob 24 within the chamber, the shank having four notches 32 to engage a spring-pressed ball 31. The switch 38, Fig. 6, comprises a fixed contact 38<SP>1</SP> and a contact 39 on a diaphragm 40 urged to the switch-closing position by a spring 52, the diaphragm forming one wall of a chamber 41 communicating either with atmosphere through ports 42, 44 or with the engine intake manifold through ports 42, 46 and a pipe 43. The ports 44, 46 are controlled by a valve assembly 45, 47, 51 urged upwardly by an adjustable spring 48. When the engine is running fast and suction is low the valve assembly will be positioned as shown in Fig. 6, but when the engine speed is low and the suction high, the valve assembly will be moved downwardly by a piston element 47<SP>1</SP>, to place suction in communication with the diaphragm and thus open the contacts 38<SP>1</SP>, 39.