Patent GB-819775-A (GB)
Title: Fluid motors
IPC: B60S1/10
Filed: 1957-10-14
Abstract: 819,775. Compressed-air engines; driving gear; valves. ANDERSON CO. Oct. 14, 1957 [Nov. 16, 1956], No. 31990/57. Classes 122 (2) and 122 (3). A fluid pressure operated motor suitable for driving a windscreen wiper.comprises a housing 11 having a closed chamber in the opposite end portions, a piston reciprocably mounted. in each chamber, rigid interconnecting means between the pistons and a shaft 17 journalled in the housing, a pulley 34 carried on the shaft, flexible means 36, 37 acting between the piston and the pulley for oscillating the pulley and shaft, an oscillating valve 62 in the housing connected with a source of fluid, means connecting opposite sides of the valve with the closed chambers and means for reversing the valve to reverse the piston movement. The opposed pressure chambers 14, 15 in cylinders 13 contain pistons 21, 22 which are rigidly interconnected by a member 28 for unitary reciprocation. The axis of the shaft 17 lies in a plane perpendicular to the housing and the longitudinal axis of the cylinders. Cables 36, 37 have their outer ends adjustably secured to the member 28 and are arranged, as shown in Fig. 3, with their inner ends secured to a key 44 carried in a slot 43 in the pulley; an eccentric cam 54 may be used to vary the tension on the cables. Fluid pressure is directed alternately to the chambers 14, 15 by the oscillating valve 62 mounted on and operated by the end of the shaft 17 remote from that to which the wiper arm is attached. Resilient piston-cushioning pads 31, 32 are provided at the ends of chambers 14, 15. A valve block 12 contains admission and exhaust ports and passages and a slide valve 60 with a manual control 97, Fig. 2, for " on " and " off " control. With the valve 60 in the " on " position, Fig. 5, pressure is admitted through port 78 to a valve chamber 72 and through port 81 to a chamber 89 and thence via ports 70 and 68 and 66 to the pressure chamber 14 to drive the piston to the right, Fig. 2, the fluid in chamber 15 being simultaneously exhausted through passage 69, ports 71, 80, passage 83 and port 86 to the exhaust port 92 under the oscillating valve 62; when the latter is swung through a " kick " mechanism to its reversing position, Fig. 9, the port 85 is put into communication with port 92 and pressure is applied to chamber 15 via, port 86 and passage 83 and ports 80 and 71. When the valve 60 is moved to the " off " position shown in Fig. 6 pressure is continuously applied to the chamber 15 via ports 78, 71 to maintain the wiper in the " parked " position. The " kick " mechanism of the valve 62 comprises a lostmotion device between the shaft 17 and a cam element 117, Fig. 9, and a trip-washer or driver 144 which engages a rectangular portion formed on the end of the shaft. Lugs 148, 149 on the trip-washer bear upon the edges of cams 119, 120 which in turn engages notches 136, 137 formed in the oscillating-valve-carrying member 132. The cam element 117 is engaged by spring-loaded rocker arms 114, 115 with detents 125, 128 which effect a snap-action as they are moved into engagement against the spring 122.