TECHNICAL FIELD

The present invention relates to an adjustable wheel suspension for utility vehicles according to the preamble to the following Claim 1.

BACKGROUND ART

In, for example, EP 1 180 474, an arrangement for adjustable wheel suspensions is already known, but, in the past, complicated solutions have been used that have a large number of moving parts in order to obtain an integral height adjustment function, in particular with multi-wheel suspensions of the bogie type.

DISCLOSURE OF INVENTION The object of the invention is to create a simple mechanism for adjustment between different height positions and working positions of a multi-wheel suspension for a utility vehicle.

This object is achieved by means of the wheel suspension according to the invention, with the characteristics that are described in the following Claim 1.

DESCRIPTION OF DRAWINGS

The invention will be described below in greater detail, with reference to the attached drawings, in which Figure 1 is a view from the back of a trailer of a type that can be provided with the wheel suspension according to the invention, Figure 2 is a view from the side of the same trailer in a tipping position and provided with an interchangeable open container, Figures 3-5 show schematically the wheel suspension in different working positions in large scale, and

Figures 6-9 show the wheel suspension in smaller scale, from the side and from above in different views of a rear part of the left side of a trailer.

MODES FOR CARRYING OUT THE INVENTION

The wheel suspension according to the invention can be used on different types of wheeled vehicles for transporting loads, where there is need of a bogie that is adjustable between a movable and fixed state and where a vehicle frame is required that is adjustable between different height positions, such as, for example, in the case of trailers of the cargo shifter type 1 , examples of which are shown in Figures 1 and 2. The basic construction of a trailer of this type comprises a chassis 2 with a frame 3 and wheel suspension 4 for the wheels 5-8, of which there are at least two on each side, forming a combined unit, commonly called a bogie. On heavy vehicles, trailers or tractors there are also front wheels, but, in principle, a trailer with a bogie according to the invention can consist of two pairs of wheels and a towing device arranged at the front end of the frame. In addition, the trailer in the example has a superstructure in the form of a shifter unit 9 with tipping frame 10 and open interchangeable container 1 1 , that is a loose container that can be tipped off and positioned for loading, and exchanged for a new container. For this purpose, a height-adjusting function is advantageous, so that it is possible to lower the frame to a lower height in the unloading and loading positions, that gives a less steep incline for pulling the container onto the trailer, and to raise it to a greater height in the driving position.

The wheel suspension 4 according to the invention is, as shown by for example Figure 1 , constructed, on each side of the trailer, of a rigid suspension part 13 mounted on the frame 3 of the trailer in such a way that it can pivot around a horizontal shaft 12, and two supporting arms 14, 15, one for each wheel 16, 17, arranged so that they can pivot around the same bearing shaft, one forward-directed supporting arm 14 for the front wheel 16 and one backward-directed supporting arm 15 for the rear wheel 17. The

wheels are mounted, in such a way that they can rotate, on separate wheel axles 18, 19 at the outer end 20, 21 of each supporting arm, the inner end 22, 23 of which is mounted on the frame 3 of the trailer. Each supporting arm can, in principle, have a separate pivot point, that in addition is separate from the pivot axle 12 of the suspension part 13, but common axles have great advantages.

Due to the fact that the rigid suspension part 13 can be pivoted around its horizontal pivot axle 12 and can either swing freely or be locked in a symmetrical position or inclined in one direction or the other, and due to the fact that the supporting arms 14, 15 can, in addition, be connected rigidly to the suspension part or angled in relation to each other and to the suspension part, a number of operating positions and modes are made possible.

The controlled positions and modes of the suspension part 13 are achieved due to the fact that linear force devices are arranged between the frame 3 and the suspension part, which linear force devices are arranged either to allow the pivoting movement of the suspension part within a limited angular range or to lock the part in a selected rotational position. In the example, two piston cylinders 30, 31 , of for example pneumatic or hydraulic type, are arranged symmetrically on each side of the trailer around the imaginary vertical plane 24 and are attached by one end, in the example the cylinder end 28, 29, to the longitudinal frame member 25 of the frame 3 in such a way that they can pivot on separate horizontal bearing shafts 26, 27. At its other end, in the example the piston rod end 32, 33, each piston cylinder is connected to the pivoting suspension part 13 at separate locations 34, 35 that are at a distance from each other and at a distance from the pivot axle 12 of the suspension part and are positioned in such a way that the longitudinal axes 36, 37 of the piston cylinders do not intersect the pivot axle 12, in order to create a turning moment.

It can be said that the pivot axle 12 and the connection points 34, 35 form the corners of an imaginary triangle with its apex pointing downwards. The connection points 34, 35 are movable, due to the fact that the ends of the piston rods have spindles 38, 39 or rollers that can run in guides 40, 41 respectively on the suspension part 13. The two guides extend in such a way that the two opposing piston cylinders are essentially horizontal, that is they extend with essentially horizontal longitudinal axes 36, 37 in a neutral position and can be angled upwards and downwards in other positions.

In the example, the suspension part 13 has a selected configuration, but it can have a completely different design. It consists of a rigid unit, that is arranged on the pivot axle 12 in such a way that it can pivot and comprises, in the example, a rigid bracket 42 with two arms 43, 44, that meet at the bottom at the pivot point 12 and that have an upper part 45 at the top, which upper part, in the example, is in the form of a slightly angled inverted V, with two arms 46, 47, that can be constructed as box girders, in which the piston cylinders 30, 31 are inserted, and that have guides 40, 41 that can be constructed as elongated slots in the walls of the girders. Each slot is delimited at its ends by outer and inner stops 48-51 , against which the spindles 38, 39 make contact to limit the pivoting movement of the suspension part or to lock it completely in a selected position, determined by the positions of the piston cylinders 30, 31.

According to the invention, a second pair of linear force devices 52, 53 is arranged, each of which is arranged between the suspension part 13 and the respective supporting arm 14, 15. These consist of piston cylinders, that are attached at one end, for example the cylinder end 54, 55, to the upper part

46 in such a way that they can rotate around a spindle 56, 57 and, at the other end, in the example the piston rod end 58, 59, are attached to the respective supporting arm by means of a spindle 60, 61 at a distance from the pivot point 12, in such a way that they can rotate. The piston cylinders are arranged to control the angular positions of the supporting arms in relation to

the suspension part or alternatively to allow a movement in relation to this, for example a springing movement if such a function is selected, for example by the piston cylinders being allowed to change length during the springing movement, for example by means of compressed air.

By means of the wheel suspension according to the invention, adjustment of the two pairs of wheels 5-8 between different operating positions and modes is made possible, for example for adjusting the vehicle for different terrains by, for example, letting the wheel suspension float freely, so that the pairs of wheels are allowed to follow the surface irregularities and by selecting different clearances, either with floating or locked suspension, with the wheels at the same axle distance or different axle distances to the frame. The wheels have been omitted from the side views for the sake of clarity.

Figure 3 shows the operating mode with floating bogie with the supporting arms in the neutral position, when the horizontal piston cylinders 30, 31 are in a central position and do not lock the suspension part 13 that is thus able to float, and the inclining piston cylinders 52, 53 are similarly in a central position as far as their linear change of length is concerned. In this position, all four piston cylinders can be locked by means of their hydraulic fluid. Alternatively, the horizontal piston cylinders 30, 31 can be unloaded and allowed to follow the floating movement, when the spindles 38, 39 make contact with the respective stops 48-51 , whereby a damped floating movement is obtained. The lower, vertical or inclined piston cylinders 52, 53 can also either be locked or can move with hydraulic medium damping or with a spring function.

Figure 4 shows an operating mode in which the upper, horizontal piston cylinders 30, 31 are extended to their inner stops 49, 51 and remain in this position by the action of the hydraulic fluid pressure. The suspension part 13 is thereby locked and creates fixed positions for the upper attachment points of the inclined piston cylinders 52, 53, whereby the piston cylinders can be

set in selected extended positions, that are locked by means of the hydraulic fluid pressure, illustrated in Figure 4 as a central position for a medium height of the trailer frame 3 and with both pairs of wheels in an active load-bearing position, on a horizontal surface.

Figure 5 shows a floating bogie, that is a suspension part 13, similar to the operating mode in Figure 3, but in fully deflected position, where the end position is reached by the outer stop 30 of the front guide 40 coming into contact with the spindle 32 of the front horizontal piston cylinder 30, while at the same time, the hydraulic system locks the same piston cylinder. The front wheel is accordingly in its highest position, on account of the unevenness of the ground.

Figure 6 shows a locked bogie similar to the position in Figure 4, but where the front wheel is raised to the top position by the front inclined piston cylinder 52 being maximally retracted and accordingly by the front supporting arm 14 being pivoted up around the pivot axle 12.

Figure 7 is a partial view from above of the rear part of the trailer, showing more clearly the supporting arms 14, 15 and their mounting on the pivot axle

12, that can be physically constructed in the form of a tube that extends under the trailer and, at its opposite end at the right side of the trailer, forms a corresponding mounting for the supporting arms and suspension part of the right wheel suspension. These parts and the piston cylinders have been omitted in Figures 7 and 8 for the sake of clarity.

Figures 8 and 9 are views corresponding to Figures 6 and 7, but with the piston cylinders and the suspension part omitted.

The invention is not limited to the examples described above and shown in the drawings, but can be varied within the framework of the following claims. The piston cylinders can be comprised in a pressurized medium system, that

is advantageously hydraulic, but can be solely pneumatic or combined with air suspension, where the inclined piston cylinders can be given a spring function. The bogie can alternatively be a so-called triple bogie. The bogies on the left and right sides of the trailer are suitably mounted separately so that they can float individually in response to the unevenness of the ground, but they are advantageously synchronously controlled in an integrated operating system, for example a hydraulic system. The horizontal piston cylinders can alternatively be connected to the frame in such a way that they can move.