A SUSPENSION SYSTEM FOR THE STEERING AND DRIVING WHEEL IN A VEHICLE

Abstract: A suspension system for the steering and driving wheel in a vehicle, wherein a hydraulic cylinder (2) is used as suspension and wherein the same cylinder functions in form of a fulcrum pin as the bearing of the steering and driving wheel (3) turning motion and wherein the power transmission to the wheel is effected with a hydraulic system by means of a hub motor (4) connected with the same. The cylinder body (2) of the hydraulic cylinder and the dead body of the hub motor (4) are joined together forming a rigid unit.

Description: A SUSPENSION SYSTEM FOR THE STEERING AND DRIVING WHEEL IN A VEHICLE The invention relates to a system according to patent claim 1 by means of which the turning and driving wheel of a vehicle is suspended to the vehicle body. Previously known is the utilization of hydraulic cylinders as a vehicle spring and attenuator when the cylinder fluid is con¬ nected by delivery tubes to a hydraulic accumulator, whereto the fluid flows or from where it flows back. Baffling is produced for instance by choking the delivery tubes. A cylinder is used to suspend the turning wheels also as a s.c. king bolt while letting the piston revolve in the cylinder in the turn¬ ing motion direction. The rigidity of the spring suspension has been adjusted with the cylinder pressure or degree of attenuat¬ ion and the ground clearance is, as is well known, adjusted by a cylinder with spring function. As example the German pub¬ lication 1 120 290 is mentioned. In the first place, the known solutions have been applied to private cars with advanced suspension automation. As to their construction and properties, they do not fit to low-speed vehicles or working machines. In working machines, such as excavators and loaders, there is no reason use the suspension at all while working. To prevent swaying during transportation of loads with working machines, the suspension may be kept in function only either in the front or rear wheels. In many cases all the working machine wheels are wanted to be driving, whereat power transmission must also be arranged for the driving wheels and often also spring suspension. As it is known, the power transmission is effected over the cardan shaft and by means of hub motors. For example, in publication DE-1 120 290 the cylinder portion of the hydraulic cylinder is connected to a body, on which the wheel is fastened with bearings, and which is the hub part of the wheel. The fluid motor is an independent detachable device that transmits the rotation motion over the hub centre to the brake drum illustrated in the figure. In this construction the hydraulic motor is not, as is not any part of it, a supporting structure, neither does any device, related to wheel suspens¬ ion, be in contact with it. The construction becomes quite complicated when the hydraulic driving motor is made easily detachable and the hydraulic motor bearing is not utilized as bearing for the wheel. By means of the system according to the invention a decisive improvement of the suspension of a steering and driving wheel is achieved and the invention is characterized in what is presented in the patent claims. The most important advantage of the invention is the fact that in a working machine with hydraulic power transmission also the turning wheels can be provided with a simple and adjustable suspension and since the hydraulic cylinder functions as a suspensory element, this cylinder can be utilized by carrying out with it vertical working machine motions, especially when it is the question of slow and accurate motions. The wheel bearing system is advantgeously arranged with a hydraulic hub motor, on the rotating part of which the wheel is directly fastened. The wheel and the hub motor are supported from the motor dead part by means of suspension to the vehicle body or axle. Wheel suspension from the axle means that this solution offers an advantageous possibility to increase the track gauge by utilizing a telescopic axle. In the following the invention is described in detail with reference to the enclosed drawing, wherein Fig. 1 is a wheel suspension system. Fig. 2 is a hydraulic system of a suspension system. Fig. 3 is a wheel suspension system in an extending telescopic axle. Fig. 4 is a hydraulic hub motor. Figure 1 shows the wheel suspension of a working machine furnished with a body 1. Wheel 3 has a motor 4 in its hub. The motor is operated with hydraulic pressure and includes also the wheel bearing. The one hub motor end is dead and comprises and end component 15, the lower part of which is a ball and socket joint 6. From this joint a triangular support arm 5 extrudes to the vehicle body 1, into which it is articulated allowing the ball and socket joint to move vertically. On the end component 15 there are auxiliary parts, for instance fasteners 13 and 18, by means of which the cylinder part of the hydraulic cylinder 2 is fixed to the end component. Due to the fasteners, the cylinder and the motor body are one rigid part. The piston of cylinder 2 is articulated from its end to body 1. Wheel 3 is thus supported on the ball and socket joint 6 and the cylinder piston rod. The wheel rotation motion is transmitted as a push/ pull rod motion to an articulated loop 7, on which the rod is fastened. The hydraulic pressure fluid is brought to the hub motor and the cylinder over hoses (not illustrated) . The wheel suspension yields only if the cylinder pressure fluid can flow into the cylinder or out from it. The wheel turns by rotating it around its axle, which runs from the upper joint-point of the piston rod to the ball and socket joint 6. Cylinder 2, in the first place its piston and piston rod, function in assocition with the ball and socket joint 6 as a turning bearing of wheel 3. The wheel steering geometry can, as it is known, be modified by changing the location and direction of the hydraulic cylinder or the location of the ball and socket joint. The ball and socket joint can also be advantageously sited in the cylinder lower end. Figure 2 shows an application of a hydraulic circuit, where cylinder 2 is double-acting and the lower part of its piston connected to a hydraulic accumulator 10 and the upper part of the piston connected to a fluid container 9. In the hydraulic accumulator the pressure fluid is separated by a membran 14 from the gas space, where nitrogen is used in suitable pressure. The nitrogen pressure, for instance 150 bar, is adjusted by valve 12, whereby cylinder 2 functions as sus¬ pension compressing or expanding the gas. In the tube line there is a valve 8 to block suspensive function of the cylinder. The valve can also be pressure-choking, whereby the degree of damping the suspension can be increased. There can also be a valve or a choker in the line leading to container 9, whereby it is possible to adjust suspension while the wheel is moving downward with regard to the body. Figure 3 shows a cylinder turned upside down, whereby the piston is rigidly fastened to the hub motor body 15. Piston rod 17 is supported by parts 16 and 18 on the hub motor end. One end of cylinder 2 and the lower triangular support arm 5 are fixed to axle 21, that moves telescopically in a bigger axle 19. By means of cylinder 20 the axle 21 is pushed outward allowing increasement of the track gauge. The steering arm system, leading to loop 7, is kept in function by means of com¬ pensation cylinders or compensation rods. During working machine operation, increasement of the track gauge means additional working stability and, in many cases, it is possible to work without outriggers. Just the combination of suspension and hub motor, according to this invention, is well suited to be mounted on the end of an telescopically extendable axle, whereby even the wheel can still be steering. The end of a telescopic axle is sufficient as a fixation point for the suspension elelments and wheel fastening. Figure 4 shows a motor wich has a rotation part (a) and a dead body portion (b). In the dead end there are supporting parts 16 and 18 for hydraulic cylinder mounting. In the same end there is also a ball and socket joint 6 for wheel suspension. In figure 2 there can, of course, instead of container 9, be also a hydraulic accumulator, whereby the suspension circuit can be totally disconnected from the other hydraulic circle of the machine. Most generally, valve 8 is totally closing and opening and, in addition, there can be in the line a pressure restricting valve and choke valves either parallel or in progression. While working with a working machine, there can be situations, where suspension is needed and situations, where suspension could cause dangerous swaying. Therefore, in the wheels, at least in either end of the working machine, suspension should be provided, which could be switched on and off upon need. During operation, suspension may not be used in lifting and excavation situations, because it causes violent jerks by sudden load dropping and releasing situations. It is easy utilize the suspensory cylinder for effecting the working machine vertical motion by connecting the suspensory hydraulic circuit to the working machine operational hydraulic circuit. The pressure fluid volume in the suspensory circuit can thereby be adjusted eihter to increase the ground clearance or to carry out the vertical motion. Track gauge enlargement increases the vehicle stability during operation and replaces often separate outriggers.

Claims: PATENT CLAIMS 1. A suspension system for the steering and driving wheel in a vehicle, wherein a hydraulic cylinder (2) is used as suspension and wherein the same cylinder functions in form of a fulcrum pin as the bearing of the steering and driving wheel (3) turn¬ ing motion and wherein the power transmission to the wheel is effected with a hydraulic system and by means of a hub motor (4) connected to the same, characterized in that the cylinder body (2) or piston (17) of the hydraulic cylinder functions as suspension and as a fulcrum pin and is fastened to the dead end (15) of the hub motor. 2. A system according to patent claim 1 characterized in that the ball and socket joint (6) of the lower support arm (5) is astened to the said hub motor end (15) . 3. A system according to patent claim 1 characterized in that the ball and socket joint (6) of the lower support arm (5) is fastened to the lower end of the said hydraulic cylinder or close to it. 4. A system according to patent claims 1, 2 or 3 characterized in that in order to increase the rigidity of the suspension system, it must be possible to block the suspensory effect of the hydraulic cylinder (2) . 5. A system according to any of the above patent claims 1 - 4 characterized in that by means of the hydraulic cylinder, which is connected to the hub motor, it is possible to carry out the operational motion of a working machine when the hydraulic cir¬ cuit of the suspension is connected to the operational hydraul¬ ic circuit of the working machine. 6. A system according to any of the above patent claims 1 - 5 characterized in that in the pipe line between cylinder (2) and hydraulic accumulator (10) there is a valve restricting the flow of pressure fluid. 7. A system according to any of the above patent claims 1 - 6 characterized in that the cylinder (2), from its upper end, and the lower support arm (5) are fastened only on the end of a telescopically extendable axle (21) allowing to change the track gauge by extending or shortening the said axle. 8. A system according to any of the above patent claims 1 - 7 characterized in that the dead end (15) of the hub motor forms a portion of the supporting construction in the wheel suspens¬ ion system.

Inventors: RAUNISTO YRJOE, RAUNISTO, YRJOE
Applicants: RAUNISTO AIRI, RAUNISTO, AIRI
Application year: 1992
Main classification: B60G3
IPC codes: B60G3, B60G17