GB775329A - Improvements in or relating to window washing devices for mechanically propelled vehicles - Google Patents

Abstract

775,329. Air pumps on motor vehicles. BOSCH GES., R. May 16, 1955 [July 3, 1954], No. 14008/55. Class 79(3). [Also in Groups XXIII, XXV and XXVIII] Relates to an air pump for operating a window washing device on a motor vehicle (see Group XXIII). The window washing device comprises a container 1, Fig. 1, for washing liquid and a diaphragm air pump 3 to pressurise the liquid in the container to urge the liquid along a supply line 6 past a control valve 7, the pump being operable by the suction in the inlet manifold 5 of the vehicle internal combustion engine. The air pump 3 is mounted on the mouth of the container and is connected by a pipe 4 with the intake manifold 5 of the vehicle engine. Referring to Fig. 3, the air pump 3 comprises upper and lower chambers 24, 25 separated by a diaphragm 22, urged to the position shown by a spring 26. The chamber 25 is formed in the base 31 of the pump which base has a bore 28 communicating with the outside atmosphere and controlled by an inlet valve 27, and a bore 30 communicating with the interior of the container 1 and controlled by an outlet valve 29. Another bore 38 in the base 31 connects with the supply pipe 6 and by a pipe 39 to a point near the bottom of the container 1. Positioned between the base 31 and the mouth of the container is a gasket 32 having a depending tube 37. The tube 37 prevents the filling of the container beyond the level 40, Fig. 3, so that some air is always trapped in the top of the container. In operation when the vehicle throttle is only slightly open and there is maximum engine suction, the diaphragm 22 is raised against the spring 26 so that air is drawn through the bore 28 and valve 27 into the chamber 25. When the throttle opening is increased suction is reduced and the spring urges the diaphragm to the position shown in Fig. 3, to expel the air from the chamber 25 through the outlet valve 29 and bore 30 into the container. When the pressure in the container reaches a predetermined value the back pressure on the diaphragm opposes its motion and balances the differential effect of the maximum suction in the manifold 5 and the spring 26, so that the pumping action ceases.