Patent GB-653258-A (GB)
Title: Improvements in vehicle suspension devices
Inventor: NEALE FRED
IPC: B60G17/048
Filed: 1947-10-15
Abstract: 653,258. Oleo-pneumatic suspension devices. MARSTON, W. W. Oct. 15, 1947 Nos. 27583 and 29338. [Class 108(iii)]  A fluid actuated vehicle suspension device comprises a pair of telescopic members defining at least one hydraulic liquid filled working space; a first variable volume container for compressible fluid and acted upon by the liquid in the working space; a second variable volume container for compressible fluid and acted upon by hydraulic liquid; restricted communication between the containers; valve means controlling the supply of liquid to the device from an extraneous source; and valve operating means responsive to relative movement of the telescopic members, so that the latter assume a predetermined relative position, the valve means being operated to introduce or extract liquid into or from the device to restore the members to their predetermined relative position on the vehicle being loaded or unloaded in order to maintain the resilience of the device under varying load conditions. In the arrangement according to Fig. 1, a liquid-filled cylinder 1 and a piston 2 slidable therein, are adapted for connection to a vehicle axle and chassis respectively. The cylinder is divided into chambers 4, 5 and 6 by a liquid-tight partition 7 and an apertured partition 8. An air bag 10, inflatable through a valve 11 and disposed within chamber 4 is connected through a restricted passageway 13 with an air bag 12 disposed within chamber 5. A valve 15 which its-resiliently connected by a rod 19 to an extension 3 of the piston 2 controls the flow of liquid to and from the chamber 4 in dependence upon substantial relative movement of the piston 2 and cylinder 1 thereby to restore the piston and cylinder to their predetermined relative positions. Rapid relative motion of the piston and cylinder during motion of the vehicle and contraction of the device due to increased loading of the vehicle, are cushioned by the air bag 12. Liquid damping of the valve 15, through a restriction 25, occurs during rapid movement of the valve and one or more restricted duets 24 also damps movement of the piston 2. Extension of the device may be cushioned by a third air bag which may be connected through a restricted passage to a fourth air bag. In another embodiment, Fig. 2, a hollow piston 31 adapted for connection to a vehicle axle or the like is slidable in a cylinder 32 which is rigidly connected to a head 34 and adapted for connection to the vehicle chassis or the like. A container 35, bolted to the head 34 is divided into upper and lower chambers 37, 38 which house annular rubber air bags 39 and 40 respectively. The rubber bags surround a conduit 41 which communicates through a duct 51 in the head 34 with a tubular member 49 extending into the piston 31, and each bag is provided with a restricted bore connection 42 or 42<SP>1</SP> into a valve-mechanism block 60. The chamber 37 communicates through a duct 56 with one working space 48 between the cylinder 32 and a housing 33 therefor, while the chamber 38 communicates through the conduit 41, duct 51 and tube 49 with a second working space 47. In operation, contraction of the device is cushioned by the air bag 40, while extension of the device is cushioned by the bag 39. Evenly distributed liquid pressure on the bags 39 and 40 is ensured respectively by a perforated sleeve 58 in the chamber 37 and perforations in the lower part of the conduit 41. Equalisation of liquid pressures in the spaces 47, 48 when the piston and cylinder are in their predetermined relative positions, is effected by one or more grooves 59 in the cylinder wall. The valve mechanism in the block 60 functions to maintain the predetermined relative position of the piston and cylinder under varying vehicle load conditions and comprises chambers 61 and 63, Fig. 3. separated by a diaphragm valve 62 which permits restricted air flow between air bags 39 and 40 only when the air pressures therein are substantially equal. Increase of vehicle loading therefore disconnects the bag 40 from bag 39 and liquid pressure, through 'a duct 65 in the partition 36 and the block 60 to a valve chamber 66, opens a normally centrally located spring loaded valve member 68 to connect the working space 47 with a pump inlet 70. Equalisation of liquid pressures in the spaces 47 and 48 restores valve 68 to its normal position and consequent equalisation of air pressures in bags 39 and 40 reconnects the bags 39 and 40 through the diaphragm valve 62, the bag 40 being extended to its predetermined volume by moulded-in springs 71, Fig. 2. Decrease in vehicle loading expands the bag 40, diaphragm valve 62 closes and liquid from chamber 37 flows via a duct 72, Fig. 3, to the other end of the valve member 68 to communicate the duct 65 with an exhaust pipe 76, until the piston and cylinder are restored to their predetermined relative positions, whereupon the bags 39 and 40 are reconnected and the bag 40 contracts to its predetermined volume under the action of its springs 71. For charging the device, air under pressure is admitted through a non-return valve 80, a bore 83 of a plunger 82 and thence to bags 39 and 40 via ducts 85 and 86 respectively. Valve 84 lifts and air pressure acts through a duct 87, on a spring-loaded plunger 88 which when the pressure in the air bags reaches a predetermined value opens the valve 68 to the liquid pump inlet pipe 70, to charge the chamber 38, conduit 41, duct 51 and space 47. Movement of the piston to its predetermined position relative to cylinder 32 connects the space 47 to the space 48 through the groove 59 and allows hydraulic liquid to fill the space 48, duct 56 and chamber 37. The liquid pressure then closes valve 84 via ducts 72 and 73 and valve 68 via duct 72, the plunger 88 rising under the action of its spring 89. The device may be charged or recharged with air alone and the pressure of this air may be less than the working pressure of the device. In a further modification, the air bags 10, 12 or 39, 40 may be replaced by pistons slidable in the respective chambers. In the application to the arrangement according to Fig. 2 the sleeve 58 is not perforated and a lower portion thereof constitutes a wall for a chamber of variable volume corresponding to bag 39. Similarly, conduit 41 is not perforated and is provided with an opening at its lower extremity. The pistons are slidable coaxially on conduit 41, the lower piston being spring-loaded to correspond to springs 71 of the bag 40. Either of the arrangements according to Fig. 2 may be such that increased loading on the vehicle to which they are attached tends to extend the device and viceversa, in which case the springs 71 are provided with bag 39 or in the modification the piston equivalent to bag 39 is spring loaded and the connections of chambers 37, 38 reversed. Also the area of piston head 46 presented to space 48 is greater than that of the head presented to space 47.