Patent GB-458379-A (GB)
Title: Improvements in and relating to motor vehicles
IPC: F04C18/18
Filed: 1935-09-16
Abstract: 458,379. Gear pumps. OSHEI, C. H., 3, General Motors Building, Detroit, Michigan, U.S.A. Sept. 16, 1935, Nos. 25634 and 25635. Convention dates, April 24 and July 3. [Class 110 (ii)] [See also Group XXXI] A gear pump for operating, by suction or pressure, windscreen-wipers or other accessories on a motor vehicle, is formed by enclosing the meshing sections of a pair of toothed gears in the transmission system of the vehicle by a lubricant sealed housing, a port in the housing adjacent to the point of intermesh of the gears leading to the accessory. Several arrangements are described including divided housings allowing for relative lateral movements of helical gears. As shown in Figs. 3 and 4, the gears utilized comprise a pinion 7 on the main transmission shaft 5 and a countershaft gear 8 rotating in lubricant in the gear casing 1. The meshing sections are enclosed by a housing 10, Fig. 4, comprising side walls 12 and arcuate transverse walls 13, 14 conforming to the diameters of the gears, a conduit 2 leading from the point of intermesh to the accessory. The housing is hung on the countershaft by an extension 24 and held in engagement by a pin 22 which may allow axial play. The arrangement may be applied to a pinion engaging an internally-toothed wheel, Fig. 5 (not shown). In the case of helically cut gears with lateral play, the housing may be applied between one of the transmission gears and an idler, which is constrained by the housing to accompany the transmission gear in any lateral movement, the conduit being flexible. Alternatively, the teeth of one of the transmission gears 6<1>, Fig. 12, may be shrouded by end discs 20<1> closely fitting ground seating surfaces 30 on a housing 14<1> straddling the other gear and carrying the arcuate gear-fitting transverse walls 16<1>, 17<1>, the upper gear and the arcuate sealing wall 16<1> being widened according to the degree of lateral play. The housing may be loosely located by a pin 251 and pressed into engagement by a spring 31. The pin may be tubular to form part of the conduit, a rubber bushing rendering the fit air-tight. In vehicles in which the gear-changing means includes synchronizing cones, the back of a cone may shroud one end of the teeth of the gear 61, the cone being shouldered to ride on the bearing surface 30 of the housing, Fig. 16 (not shown). Such an arrangement is also shown in Figs. 17 and 18 wherein the end wall of the transmission casing 47 is chambered to receive, and in part form the housing for, the gears 6<11>, 8, the arcuate walls 16<11>, 17<11> being integral therewith and the housing being completed by the back of the synchronizing cone 15 co-operating with a plate 48 secured in position by screws 39<1> with spring washers 40<1>. An alternative form of housing for allowing lateral play of the gears, whilst maintaining the liquid seal, comprises upper and lower sections 51, 55, Fig. 20, shaped to fit the respective gears and slidably connected by a dovetail joint 53, 54. In this form the conduit passage 27<11> is formed at the junction of the arcuate walls and leads to a recess containing the tubular guiding and mounting pin 25". An augmented air seal may be provided by oil grooves 62 receiving oil under pressure as from between the teeth of the gears on the opposite side of the point of intermesh to that of the pump chamber. In forms having housing walls with resilient means for taking up wear, such as the spring washers 40<1>, Fig. 18, a layer of cork, leather, &c. may be interposed between the removable wall and the central or body part of the housing. Alternatively, the housing wall may be provided with a yieldable liner supported by spring extensions and guided in its movements by a tubular stem slidably fitting the conduit, Fig. 14 (not shown). To prevent noise caused by sudden entry of air between the tooth spaces as they emerge from the housing, the clearance between the housing and the gears may be graduated, or venting grooves such as 19, Fig. 3, or 35, Fig. 12, may be formed in the arcuate walls. Instead of, or in association with such means, a relief valve may be provided in the conduit line, Fig. 15 (not shown), the relief valve being put out of action when the valve connecting the pump to the accessory is opened. To prevent drainage of oil from the rising teeth of helical gears, the lower wall of the housing may be extended or the gear teeth may be partly shrouded. To ensure a supply of oil around the lower gear, a retaining flange or wall may be provided in the transmission casing. Specification 442,068 is referred to.