Patent GB-706734-A (GB)
Title: Improvements in or relating to a windshield cleaner
IPC: B60S1/10
Filed: 1951-11-23
Abstract: 706,734. Compressed air engines; vacuum engines ; engine valve gear. TRICO PRODUCTS CORPORATION. Nov. 23, 1951 [Dec. 8, 1950], No. 27557/31. Classes 122 (2) and 122 (3). [Also in Group XXIII] Relates to a pair of flexibly interconnected and fluid pressure differential operable piston motors for driving a pair of windshield wipers (see Group XXIII). As shown in Figs. 1, 2 and 3 two suction motors having cylinders 21, 22 and pistons 25, 26 respectively are mounted in a single casing 1. Piston rods 23, 24 extend from opposite sides from each piston and the adjacent ends of the rods are connected to flexible cables 31 and 35 which cables drive wiper blades 40, 42, respectively. Arranged in the casing 1 longitudinally of and between the cylinders 21, 22, are two passages 65, 66. The passage 65 is connected at one end by a port 68 to one end of the cylinder 21 and at its other end by a port 67 to the opposite end of the cylinder 22. Similarly the passage 66 is connected by a port 70, adjacent port 68, to the cylinder 22 and by a port 169, adjacent port 67 to the cylinder 21. Mounted on the side and centrally of the casing 1 is a donkey motor assembly 8 comprising pressure chambers sealed by flexible diaphragms 74, 75, Fig. 6, and spaced apart by a casting 71. The passage 65 connects by a port 89 with a passage 87 extending horizontally right through the casting 71. The passage 66 connects by a port 88 with a passage 86 extending horizontally in the casting and connected to a vertical passage 83 in the casting. By the side of the passage 83 are two vertical passages 82, 81, which connect at their bottom ends to horizontal ports 85, 84, opening through the outer side of the casting. A valve 109 resiliently carried by a member 102 connecting between the diaphragms 74, 75, has a recess 110 which can either put ports 84, 85, in communication or the outer end of passage 87 and port 84 in communication..Behind the passages 81, 82, 83, there is provided in the casting a horizontal passage 78 communicating with engine suction through a pipe 13. The passage 78 has two vertical ports 79 and 80 passing through the top of the casting. Mounted for movement across the top of the casting, by means of a Bowden cable 20, is a valve plate 113 provided with recesses 114, 115. When the motors are in operation the plate is in the position shown in Fig. 8 and when it is desired to park the wiper blades the plate is in the position shown in Fig. 9. The casting 71 between the pressure chambers is enclosed by a casing 93. The interior of this casing is in communication with the exterior atmosphere through the medium of a filter 91 and an aperture in the casing below the filter. The right hand pressure chamber, Fig. 5, communicates by a passage 129 and passage 133, Fig. 4, in the casing I with a valve controlled recess 137 in the cover 3 of the cylinder 21. The left hand pressure chamber, Fig. 5, communicates by a passage 128, with a passage 132, Fig. 4, in the casing 1 and a valve controlled recess 136 in the cover 2 of the cylinder 21. Referring to Fig. 4 a valve element in the recess 137 is arranged so that the passage 133 is either in communication with the atmosphere via a hole in a cap 142 or with the cylinder 21 via grooves 140 according to the position of the piston 25. A valve element 145 is journalled in the inner wall of the recess 136 which wall has an opening 146 therein. The inner wall is part of the cover 2. The end of the valve 145 within the cylinder 21 has secured thereto a helical spring 149. At its other end the valve 145 has a portion 150 with a conical tip 151. The portion 150 can abut against the inner end of the recess 136 to seal the opening 146. A recessed member 152 is mounted for sliding movement in an enlarged portion of the recess 136. A corresponding member 153 is secured in the outer and of the recess 136 and a compression spring 154 is mounted between the members 152, 153 which are both provided with apertures, the aperture in 152 being sealable by the tip 151. A spring 155 is interposed between the portion 150 and member 152. Piston stop members 156, 157, are provided in opposite ends of the cylinder 21. In the position shown in Fig. 4 the motors are in the parked position suction being applied to the right hand side of the piston 25, the diaphragms 74, 75 are flipped over to the left as viewed in Fig. 6 and the plate 113 is in the position shown in Fig. 9. To operate the wipers the plate 113 is moved to the position shown in Fig. 8. The right side of the piston 25 will then be in communication with atmosphere through the port 69, the passage 66, port 88, passage 86, passage 83, recess 115, passage 82, port 85 and interior of casing 93. The left hand side of the piston 25 will be in communication with suction through port 68, passage 65, port 89, passage 87, recess 110, port 84, passage 81, recess 114, port 79 and suction passage 78. The piston 25 will thus move to the left while of course the piston 26 will move in the opposite direction owing to a reversed state of conditions due to the port connections 67, 70 with the cylinder 22. As soon as the piston 25 moves to the left the spring 155 urges valve portion 150 to the left to seal passage 146 and the spring 154 urges member 152 against a shoulder in the recess 136. Air is then passed to the passage 132 and thus to the left hand pressure chamber in Fig. 6. As soon as the piston 25 reaches the left hand end of its cylinder the valve 138 is operated so that suction is applied to the passage 133 and thus the right hand pressure chamber in Fig. 6. The diaphragms 74, 75 will thus flip over to the position shown in Fig. 6. Air pressure is then applied to the left hand side of the piston 25 through port 68, passage 65, port 89, passage 87 and the interior of the casing 93. At the same time suction will be applied to the right hand side of the piston 25 through port 69, passage 66, port 88, passage 86, passage 83, recess 115, passage 82, port 85, recess 110, port 84, passage 81, recess 114, port 79 and passage 78. The piston 25 will thus move to the right, the reverse conditions applying to the piston 26. As soon as the piston 25 moves to the right the right hand pressure chamber is supplied with air. When the piston abuts the spring 149, the valve 145 is moved suffieiently so that the spring 155 is compressed to allow the tip 151 to seal the aperture in the member 152. However the member 152 does not move against its spring 154 since suction is now applied through the passage 146 to the left hand pressure chamber to cause the diaphragms 74, 75 to flip over to the left as viewed in Fig. 6. Suction is then applied to the teft hand side of the piston 25 and air pressure to the right so that the piston again commences to move to the right before it can abut the stop 157. The wiper blades will thus operate through a predetermined arc of wipe and will not slap against the windscreen frame which constitutes the parked position. To park the wiper blades the plate 113 is moved to the position shown in Fig. 9. As the piston 25 moves to the right in Fig. 4 the right hand side thereof will be connected to suction via passage 83, recess 115 and port 80. Even when the piston abuts the valve 145 causing the flexible diaphragms to flip over the pressure differential in the cylinder 21 remains the same since the atmospheric connection is blocked. The piston can therefore complete its movement to the right and finally abut the stop 157. A modified form of donkey engine described with reference to Figs. 10 to 13 (not shown) utilizes a multi-hubbed piston working in a ported cylinder in lieu of the flexible diaphragms and associated recessed valve.