GB1464394A - Pressure medium suspensions - Google Patents

Abstract

1464394 Controlling vehicle suspension height ROBERT BOSCH GmbH 25 March 1974 [24 March 1973] 13046/74 Heading B7D In a vehicle having a level-regulated rear axle 16 and an unregulated front axle 1, a level transmitter 4 sensitive to the front suspension height acts through a hydraulic transmission line 9 on a level regulator 10 having a second input from the rear axle 16 and means for damping the movement of the hydraulic fluid, the level regulator 10 acting to adjust the rear suspension height in response to a difference in the suspension heights at the front and rear. The level transmitter 10 includes a diaphragm piston 7 on which the front suspension acts through a lever 3 and a spring 6 and which is located in a chamber 8 corrugated to the line 9. The level regulator 10 includes a lower chamber 26 which is connected to the line 9 and communicates with an upper chamber through the damping means 41. A diaphragm piston 11 in the lower chamber 26 is subjected to rear suspension movements through a lever 14 and spring 12, and a spring- loaded diaphragm piston 35 in the upper chamber 34 is arranged to actuate micro-switches 17 controlling operation of a pressure generating unit 25 connected to rear suspension units 15. The fluid damping means 41 comprises valve plates 32, 33 mounted on a wall 27 dividing the chambers 26, 34 by rivets 30, 31 to control flow through a bore 27<SP>1</SP> in the wall, and a damping piston 36 carried by the piston 35 and projecting into a bore 37 in the wall 27 to form a small annular gap 38. With identical height changes at front and rear fluid only moves to and fro through the line 9 so that the micro-switch 17 is not actuated, but when the heights are unequal fluid passes through the wall 27 to displace the piston 35. To prevent operation of the microswitch 17 due to transient height changes fluid can pass only through the gap 38 until the piston 35 reaches the end of its stroke and actuates the micro-switch whereupon the damping piston 37 acts directly on tongues on the valve plates 32, 33 to open the box 27<SP>1</SP> so that rapid return of the piston 35 terminates the levelling operation quickly when the correct height is reached.