Patent GB-929866-A (GB)
Title: Vehicle suspension and power system
Inventor: TAYLOR PAUL HOLLIS
IPC: B60G17/00
Filed: 1960-07-12
Abstract: 929,866. Road vehicle suspensions; spring units. TAYCO DEVELOPMENTS Inc. July 12, 1960, No. 24248/60. Classes 108(2) and 108(3). A vehicle suspension system comprises a closed fully liquid filled hydraulic circuit including a hydraulic wheel suspension unit and a conduit permitting liquid flow into and out of said unit in response to shocks and vibrations imparted to said cylinder. There may be two closed, fully liquid circuits, each including a front wheel hydraulic suspension unit and a rear wheel hydraulic suspension unit interconnected by a conduit permitting liquid flow out of said units, at least part of the liquid filling each of said circuits being a compressible polymorphic liquid, that is, a liquid capable of undergoing reversible change of non-gaseous form resulting in a change of volume at substantially constant pressure whereby changes in volume of said compressible liquid cause and permit liquid flow into and out of said units respectively. A heavy road vehicle comprises an engine 22 driving the rear wheels 32 through gears 24, shaft 26 and differential 28. The road wheels 32 and 34 are supported by A members 36 and 38 pivoted at 40 and 42 and connected to the vehicle frame by hydraulic supporting cylinders 44 and 46. A secondary support is provided by coil springs 68 surrounding the rear cylinders 44. The wheel cylinders 44 and 46 on each side are connected to a hydraulic accumulator 48 by lines 52, 54 and 56, 58 respectively and hydraulic fluid under pressure may be supplied to the system on each side by a pump 70 controlled by a valve 76. Each hydraulic accumulator, Fig. 2, comprises a heat insulated casing 82, a vaned container 84 containing a fluid capable of undergoing polymorphic transition and a compressible container 88 connected to the hydraulic circuit through a valve 92. Hot gases from the engine exhausts 64 and 66 (Fig. 1) may be directed through each accumulator, entering through pipe 98 controlled by valve 102 (Fig. 2) and leaving through pipe 100. The valve 102 is normally biased to an open position and is operated by an electric motor 104 operatively connected to one pole 108 of a switch associated with a level sensing member 120, the movable arm 112 of which is connected through the engine ignition switch 116 to the battery. At a given temperature and pressure, the selected fluid, e.g. a dimethyl silicone or benzene, is compressible and provides the resilient springing of the system. The various pipes may be made of nylon, beryllium or copper and may also participate in the springing effect. The container 84 also includes an electric heating element 122 connected through a time delay relay 132 to a pole 136 of the switch. When starting and the engine is cold, contact is maintained between the pole 136 and the arm 112 so that the element 122 is energized and the temperature of the polymorphic liquid is increased, so compressing the liquid in the container 88 and raising the level of the vehicle until a point is reached when a level sensing member 120 causes the arm 112 to break contact with the pole 136. At this point the polymorphic liquid is in the condition whereby it provides a cushioning or springing effect in the system. If the vehicle frame moves upwardly too great a distance, the circuit of motor 104 is completed and the motor is actuated to close valve 102 and so to diminish the heat transfer from the engine gases. The temperature of the container 84 thus drops and the pressure on container 88 diminishes whereby the vehicle level drops until the sensing device 120 again breaks contact with the pole 108. Should the supply of exhaust gases fail, the device will continue to function with heat supplied from the element 122, the level being determined by the point at which contact between the pole 136 and element 112 is broken. The polymorphic liquid is stated to absorb shock and a theoretical explanation is given. The valve 92 has discs 138 and 140 having restricted central orifices 142 and 144. A pressure surge in the accumulator causes the discs to open but pressure surges from the wheel cylinders closes them and restricted flow through the apertures only is permitted, causing the system to damp bounce but not rebound. It is stated that a similar system may be used in conjunction with a vehicle air conditioning plant, cooling air being used. The hydraulic fluid may also be in a circuit including power operated steering, brakes, or power operated ancillaries such as a scoop, bucket or starter, pressure drop being compensated by increase of heat supplied to the accumulator. In a modification, Fig. 3, the accumulator comprises a container 154 for polymorphic liquid in which is located the compressible bulb 158 containing hydraulic liquid connected to the wheel cylinders, and a heating coil 156. The accumulator has inlet and outlet pipes 160 and 162 connected, respectively, to hotter and colder parts of the engine cooling system, a valve 164 regulating the amount of hot or colder water admitted to the accumulator being connected to an element 174 which senses the vehicle height and is provided with damping means so that the arm is not affected by road oscillations. In a further device, Fig. 4, the vaned container 184 for polymorphic fluid may be heated by an electric coil 196 as in Fig. 2 but without the time delay relay, or by a mixture of hot and cold air drawn in through ducts 206 and 208 from the atmosphere or the vehicle heating system respectively, the mixing valve 204 being set by a reversible electric motor 220 actuated by a control device 198. In another embodiment of hydraulic accumulator, Fig. 5, having an outer chamber 232, an inner chamber 234 containing polymorphic fluid and an electric heating coil 248 having a connecting lead 250, the compressible container 240 is connected to the hydraulic wheel cylinders through pipes 242 and 244 and a passage 262 controlled by a disc valve 256 having a small central aperture 258 which may rest either upon fingers 260 or against a seating 266 so that sudden bounce is dampened whereas rebound is not. The passage 262 may be closed by a valve 268 controlled by a solenoid 272 incorporating a time delay relay and comes into play when the engine is switched off to prevent loss of level. The wheel cylinders may comprise a piston 288, Fig. 6, having damping apertures 290, and a cylinder 282 completely filled with hydraulic fluid. Another embodiment of wheel cylinder, Fig. 8, comprises a cylinder 302 having a central tubular portion 312 about which is located the shank 306 of the piston member having a piston head 308 incorporating a valve member comprising an inner member 322 sliding on the tube 312 and being capable of closing off access between the interior of shank 306 and the cylinder, an outer member 334 retained by a ring 342 and having a lip 326 whereby access between the interior of the valve and the cylinder may be prevented and a spring 338. Liquid passages 321, 322, 320 and 318 and liquid seals 310 and 316 are provided, the arrangement being that as the piston moves upwardly relatively to the cylinder, the opening 338 is compressed by movement of the member 334 downwardly, liquid passing through an annular gap 340 between the member 334 and 322, and when the piston moves downwardly, the spring is compressed by upward movement of the valve member 322 leaving a liquid passage both movements providing a damping action with the liquid being forced through the various apertures. In a further embodiment of the cylinder, Fig. 9, a stepped cylinder, 358 is provided with a fixed piston 368, 360 and a moving stepped plunger 364 having a reduced diameter portion 370 providing a damping action. A heavy duty vehicle, Fig. 10, has leaf springs 386 supporting the front wheels 384 and its rear wheels are carried by arms 390 mounted on a torsion bar 392. Wheel cylinders 394, 394 and 396, 396 are provided for each of the front and rear wheels respectively and are connected by conduits 398 to a common accumulator, the system acting for levelling and shock absorption rather than for primary support. The liquids in the wheel cylinders and accumulator in all cases may both be non- polymorphic fluids. Specification 826,370 is referred to.