Patent GB-1461361-A (GB)
Title: Suspension assembly for vehicles capable of cross-country travel
IPC: B60G17/005
Filed: 1974-01-31
Abstract: 1461361 Vehicle suspension; valves L PIETZSCH 31 Jan 1974 [31 Jan 1973] 04590/74 Headings F2S and F2V A gas/hydraulic suspension assembly for mounting on a vehicle intended for crosscountry travel, which comprises at least one hydraulic piston-and-cylinder unit 3 (referred to as the hydraulic cylinder), Fig. 1, constructed and arranged to act between the sprung mass of the vehicle 1 and a ground-engaging support, e.g. a wheel 2 or an endless track, and at least two gas/hydraulic pressure accumulators 12, 13 whereof a first accumulator 13 is permanently connected hydraulically to the compression chamber 5 of the hydraulic cylinder and a second accumulator is connected hydraulically to the compression chamber via a coupling conduit provided with an hydraulic-pressureactuated on-off valve 16 whereby with the valve open both the first and the second accumulators are resiliently operative in the assembly and with the valve closed only the first accumulator is resiliently operative and the second accumulator is hydraulically locked by the closed valve in the condition of deflection reached at the instant of closure of the valve, and which further includes an hydraulic circuit arranged to sense the cyclically-varying hydraulic pressure in the compression chamber of the hydraulic cylinder during the operation of the suspension assembly and to trap the sensed pressure at both its maximum and its minimum values in the circuit, the circuit having control means with an input to which control signals can be applied, which control means utilizes the pressure difference between the trapped maximum and minimum sensed pressures to operate the valve. Operation is similar to that of the system of German Specification 2,043,512. General operation.-A sensor (or sensors) measures the magnitude and (or only) the direction of the oscillation of the vehicle body and/or the speed of the column of fluid in the conduit 5<SP>1</SP>, Fig. 2, to operate an electromagnet 65 and cause opening of the valve 16<SP>1</SP> at a point of zero movement of the vehicle body, i.e. when the direction of reciprocation movement changes. Unlocking or opening of the valve 16<SP>1</SP> also occurs when the pressure exceeds a maximum permissible value and overcomes the effect of a spring 76 which urges a double needle-valve 60-61 to close the h.p. inlet 57 and allow the h.p. trapped below the ball 80 of the valve 16<SP>1</SP> to open that valve. The spring 76 is contacted by an adjusting screw (77, Fig. 4, not shown). Alternatively, a gauge 90 can operate the electromagnet 65 controlling the valve 60-61 if an excess pressure is recorded. Sensing of maximum and minimum pressures of fluid.-The valve 16<SP>1</SP>, Fig. 2, is by-passed by a line 30 having non-return valves 33, 34 on each side of a high-pressure conduit 36 and a line 37 having non-return valves 38, 39 on each side of a low-pressure conduit 41. Thus the highest and lowest pressures are trapped between the pairs of non-return valves. Control of use of such fluid pressures.-According to the position of the double-needle valve 60-61, either the h.p. or 1.p. conduit is connected to the space 54 of a shuttle valve 47. The needle valve 60-61 is operated by the electromagnet 65 through a lever 66, Fig. 2, or directly, Fig. 3. The h.p. side includes an accumulator 70 for high pressures up to 1000 at.