Patent GB-1015010-A (GB)
Title: Improvements in pneumatic suspensions
IPC: B60G17/052
Filed: 1964-03-16
Abstract: 1,015,010. Pneumatic suspensions. HOESCH A.G. March 16, 1964 [May 27, 1963], No. 11008/64. Heading B7D. A motor vehicle pneumatic suspension comprises an air spring 1which is disposed between an unsprung member 2 and the sprung part 3 of the vehicle and connected by a pair of conduits 4a and 4b, having non-return valves 6a and 6b, with an air reservoir 5. The non-return valves 6a and 6b are acted upon by springs 7a and 7b and may be opened by electromagnets 8a and 8b which are connected to a battery 12 and to switches comprising fixed contacts 15a and 15b and rocker contacts 14a and 14b. A push-rod 9 is connected between the unsprung member 2 and a delay device which has an output member which responds only to changes in the vehicle mean height and is not responsive to instantaneous changes, the member 11 having a head 13 which coacts with the rocker contacts 14a and 14b. At the initial position, the spring 1 and reservoir are in equilibrium. If the vehicle is loaded, the rod 9 is pushed to the position 9a and the head 13 moving to the position 13a closes the contacts 14a, 15a. The spring pressure is released from the valve 6a and in the course of the vehicle vibration, air passes the valve 6a from the reservoir 5 into the spring 1 until the suspension reaches its former height with the pushrod in the position 9. Conversely, when load is removed from the vehicle, the suspension and push-rod move to the position 9b with consequent release of pressure of the spring 7b so that the vehicle vibration causes air to flow past the valve 6b from the spring 1 to the reservoir until the correct mean height is regained. In a modification, Figs. 2 and 3, an air spring 101 located between the sprung and unsprung parts 102, 103 is in communication with an air reservoir 105 by way of a valve device 115 comprising a sliding spool 118 connected to a spring 121 and having a throat portion 118b by means of which an inlet aperture 117a from a passage 104 may be brought into communication with one or other outlet passages 104a and 104b in which are located non-return valves 106a and 1066, respectively. A narrow bore 118c connects the ends of the valve spool and the throat 118b. At the mean height, the valve spool is in the position shown, but if a load is placed upon the vehicle, the valve spool will be moved against the stop 119 connecting the apertures 104a and 117a by the throat 118b. Vibrations of the vehicle body will draw air from the reservoir 101 past the valve 106a into the spring 101 until the mean height is restored. Conversely, if load is removed from the vehicle, the valve spool moves against the stop 120 connecting the apertures 104b and 117a by the throat 118b, and body vibrations cause air to move from the spring 101 past the valve 106b into the reservoir until the correct mean height is regained. The bore 118c prevents pressure surges and acts as a delay mechanism. Adjustment of the mean height may be effected by raising or lowering the valve assembly 115. In an alternative valve assembly 215, Fig. 4, for this modification, a pair of passages 204a and 204b connect the air reservoir and bellows and are closed by two pairs of valves 222b, 206b and 222a, 206a, one or other of the valves 222a and 222b being opened according to whether load is placed upon or removed from the vehicle by a member 218a connected to the spring 221 and having stop devices 223a and 223b whose distance apart is adjustable. The member 218a carries a damping piston 218 with a calibrated aperture 218c and the lip portions of the passages 204a and 204b take account of pressure surges in the bellows and reservoir. The action of the device may be speeded by having two separate reservoirs 5a and 5b, Fig. 5, connected to the passages 104a and 104b, respectively (or 4a, 4b or 204a, 204b), the air in the reservoir 5a being maintained at a higher pressure than reservoir 5b by means of a pump 17 reciprocated in accordance with vibrations of the vehicle and equipped with non-return valves 19 and 18a (in the piston 18). In a modification to provide for a pressure difference before the vehicle is set in motion, an electrically-operated pump 22, Fig. 6, may be used for transferring air from reservoir 5b to reservoir 5a. A non- return valve 20 is provided between the reservoirs. There may be a single reservoir connected to an air spring at each wheel.