GB431969A - Improvements in or relating to pneumatic tires and inflators therefor - Google Patents

Abstract

431,969. Tyre pumps. HOSKING, O. W., Monroe, New York, U.S.A. July 20,1934, No. 21344. [Class 8 (i)] [See also Groups XXXIV and XXIX] A device, actuated by the flexing of the tyre tread, for automatically inflating tyres whilst running comprises a reciprocating pump, the casing of which is attached to the rimseating portion of the air-tube, the pumppiston being connected to the tread portion of the tube by a non-rigid member (such as a chain 65) to effect the operative stroke of the piston as the flattened portion of the tyre assumes its normal form on leaving the ground. The return (suction) stroke of the piston is effected by separate means (such as a spring 65). A relief-valve is provided to prevent excess pressure in the tyre and maintain a continuous circulation of air through the tube. In the form shown in Figs. 2 and 3, a pump cylinder 20 is clamped to the wheel-rim 12 and air-tube 15 by nuts 26, 23 respectively, the piston P being connected to the tread side of the air-tube by a chain &c. 65, as by a ball-and-socket 68, 70. The piston is normally urged to occupy the lower, or radially-outward, position shown in Fig. 3 by the tyre (which is inflated through an ordinary valve 60), but is moved towards the opposite end of the cylinder on flattening of the tyre in road-contact by the pull of a spring 40. In this movement, air trapped in the cylinder (in the previous outward movement of the piston) is forced past a one-way ballvalve 82 and through piston-ports 84, 85, 86 so that when this part of the tyre leaves the ground the return stroke of the piston (by the pull of the chain 65) forces the air through a non-return valve 78 into the tyre. A reliefvalve is fitted at a diametrically-opposite position on the wheel. This valve, shown in Fig. 4, comprises a casing 90 clamped to the rim and tube fitted with a tubular plunger 100 having a rubber-faced flange 101 normally pressed on to a seat 103 by an adjustablyloaded spring 105. In the modification shown in Fig. 5, a spring-loaded valve 147 is fitted to the head of a casing 51 mounted on the pumpcylinder. The seating-end of the tubular valvestem 142 is normally closed by a one-way ball-valve 150 past which air is admitted to the cylinder during the compression-stroke of the piston. In this stroke, air which has entered the lower end of the cylinder through a tubular valve 117, past a one-way ball-valve 130, and through piston-ports 132, 133, is forced into the tyre past a one-way ball-valve 131. During this movement, any excess pressure set up in the tyre causes the relief-valve 126 formed in the stem 117 to be moved from its seat 122. Fig. 6 shows a device for equalizing the pressures in twin tyres 157 comprising a cylinder 166, the opposite ends of which are connected to the tyres by branch-pipes 164, 165. A piston 167 is normally held in the position shown by springs 168, 169 whereby the pipes 164, 165 are placed in communication through a port 170 in the cylinder-wall. On deflation of either tyre, the piston 167 moves to close the corresponding end of the port 170 and shut off communication between the tyres. An excesspressure relief-valve 181 is fitted in one of the branch-pipes.