The present invention relates to a device at vehicle wheels for vehicles which are adapted to be driven in op- tional directions on an underlayer or ground, inter alia in a main driving direction forward. The vehicle has at least two pairs of wheels including two wheels, wherein said wheels are individually operable for rotation in clockwise as well as in counter clockwise direction. Each wheel is rotatable about an axis of rotation and it is provided or mounted such that its axis of rotation, seen from the front in a direction towards the vehicle, is loca- ted in a first plane in parallel with the main driving di- rection of the vehicle, said plane defining with a second vertical plane in parallel with the main driving direction an angle lying within an interval of 2-45°, preferably 5-25°. The two wheels in each pair of wheels are provided or mounted such that their axes of rotation are located in first planes which, seen from the front in a direction towards the vehicle, intersect under the wheels, whereby the wheels in said pair of wheels are situated in such in- clined positions relative to each other that, seen from the front in a direction towards the vehicle, parts of the wheels turned away from each other are in contact with the ground, while parts of the wheels facing each other are situated above the ground. Each wheel is provided, during driving of the vehicle on the ground, for allowing free pivoting thereof about a horizontal pivot or swinging axle which is located at right angles to the main driving direc- tion such that the axis of rotation of each wheel pivots in said first plane in parallel with the main driving di- rection.

Vehicles having the wheels mounted such that they can be driven in optional directions are previously known from the publication WO 98/28158. The wheels on these ve- hicles are provided with rollers through which they have contact with the ground. Vehicles with such wheels operate

very satisfactory in many applications, but it has been noticed that dust, gravel, sand or other particles easily penetrate into the bearing members of the rollers while driving in environments loaded with or having much such material. This might lead to quick wearing down of the bea- ring members of the rollers, which then must be replaced.

The object of the present invention is to remedy this problem by eliminating the need for rollers but yet allow the vehicle to be driven in optional directions on plain or even as well as uneven or rough grounds. This is arri- ved at according to the invention while the initially de- scribed device is provided with the characterizing fea- tures of subsequent claim 1.

Since the device according to the invention has said characterizing features, it is achieved that the wheels can be designed such that they become substantially less sensitive than previously, while they at the same time permit driving in optional directions on the ground irre- spective of whether the ground is plain or rough. Thus, the wheels permit, inter alia, driving of the vehicle in optional directions in terrain which is rough with refe- rence to unevenness as well as to its surface quality or smoothness.

The invention will be further described below with reference to the accompanying drawings, in which fig. 1 is a schematic plan view of the chassis of a vehicle having a device at wheels according to the inven- tion; fig. 2 is a front view of the chassis of fig. 1 with the wheels set in a backward turned position; fig. 3 is a side view of the chassis of fig. 2 with the wheels set in toe-in positions; fig. 4 is a front view of the chassis of fig. 1 with the wheels set in a forward turned position; fig. 5 is a side view of the chassis of fig. 4 with the wheels set in toe-out positions;

fig. 6 illustrates the chassis of fig. 4 with one wheel and a suspension device therefor; and fig. 7 is a side view of the chassis of fig. 1 and a schematically illustrated setting device.

In the drawings, there is schematically illustrated a chassis 1 for a vehicle F which is adapted to be driven in optional direction or an underlayer or ground 2, inter alia in a main driving direction HF forward or backward, lateral directions SF, in obliquely forward or backward directions, rotating directions and so on. Driving of the vehicle in optional directions means here that the ve- hicle can be driven in optional directions without having to turn the wheels in a traditional manner.

The chassis 1 includes two wheels 3,4 provided in a front wheel pair FP and two wheels 5,6 provided in a rear wheel pair BP. In association with each wheel 3,4, 5 and 6 there is provided a driving motor 7, preferably an electric motor for operating or driving the wheels in- dividually in clockwise as well as counter clockwise di- rection for moving the vehicle F in the desired direction.

Each wheel 3-6 is rotatable about an axis of rota- tion 8 and it is provided or mounted such that its axis of rotation 8, seen from the front in a direction FF to- wards the vehicle F, is located in a first plane PI in parallel with the main driving direction HF of the vehicle F, said plane defining with a second vertical plane VP1 in parallel with the main driving direction HF an angle a lying within an interval or range of 2-45°, preferably 5-25°. The two wheels 3,4 and 5,6 respectively, in each pair of wheels FP and BP respectively, are provided or mounted such that their axes of rotation 8 are located in first planes PI which, seen from the front in a direc- tion FF towards the vehicle F, intersect at a point PU under the wheels 3-6. Hereby, the wheels 3,4 and 5,6 respectively, in said pairs of wheels FP and BP respec- tively, will be situated in such inclined positions rela-

tive to each other that, seen from the front in a direc- tion FF towards the vehicle F, parts 3a, 4a and 5a, 6a respectively, of the wheels 3,4 and 5,6 respectively, turned away from each other are in contact with the ground 2, while parts 3b, 4b and 5b, 6b respectively, of the wheels 3, 4 and 5,6 respectively, facing each other are situated above the ground 2. These positions of the wheels 3-6 appear clearly from fig. 2.

Each wheel 3-6 is provided, during driving of the ve- hicle F on the ground 2, for allowing free pivoting there- of about a horizontal pivot or swinging axle 9 which is located at right angles to the main driving direction HF such that the axis of rotation 8 of each wheel 3-6 pivots in said first plane P1 in parallel with the main driving direction HF.

Each wheel 3-6 is provided for allowing locking of the wheel such that it, during driving of the vehicle F on the ground 2, can not pivot freely about said pivot or swinging axle 9 but maintain certain desired position in relation thereto. Alternatively, the wheels 3-6 may be lockable in pairs.

Seen from the side in a direction FS towards the ve- hicle F, the wheels 3-6 may be lockable in toe-in or toe- -out positions. When the wheels 3-6 are locked in toe-in positions, two planes P3, P4 in which the axes of rotation 8 for the wheels 3,5 or 4,6 in said pairs of wheels FP or BP are located, intersect under the wheels 3,6 at a point PU1 seen from the side in a direction FS towards the vehicle, whereby parts 3c, 4c, 5c, 6c of said wheels 3,5 and 4,6 in said pairs of wheels FP and BP turned away from each other are in contact with the ground 2, but not parts 3d, 4d, 5d, 6d of said wheels 3,5 and 4,6 facing each other (see fig. 3). When the wheels 3-6 are locked in toe-out positions, said two planes P3, P4 inter- sect above the wheels 3-6 at a point P01, whereby parts 3d, 4d, 5d, 6d of said wheels 3,5 and 4,6 facing each other are in contact with the ground 2, but not parts 3c,

4c, 5c, 6c of said wheels 3,5 and 4,6 turned away from each other (see fig. 4).

Each wheel 3-6 can be provided or mounted to pivot freely within a pivoting sector in a forward and backward direction relative to a vertical plane VP2 in which the horizontal pivot or swinging axle 9 is situated.

The pivoting sector may have an angle ß of maximum about 30°, preferably maximum 20°, and each wheel 3-6 can pivot as far or about as far forward as backward relative to the vertical plane VP2.

The wheels 3-6 may be lockable in such toe-in posi- tions that the distance A between their points of contact with the ground 2 is the greatest.

The wheels 3-6 may preferably be provided to swing or pivot freely about the horizontal pivot or swinging axles 9 during driving of the vehicle in the main driving direc- tions HF and other directions with the exception of late- ral driving directions SF relative to the main driving direction HF. The wheels 3-6 and/or the pairs of wheels FP, BP may also be provided or mounted such that they are locked during driving of the vehicle F in said lateral driving directions SF or substantially in said directions such that they thereby do not pivot or swing about the horizontal pivot or swinging axles 9.

The wheels 3-6 can preferably be locked such that they do not pivot about the horizontal pivot or swinging axles 9 when the vehicle during driving changes its dri- ving direction from main driving directions HF and other directions separate from the lateral driving directions SF to said lateral driving directions SF. The wheels 3-6 are preferably releasable such that they pivot about the hori- zontal pivot axles 9 when the vehicle F changes its dri- ving direction from lateral driving directions SF to other driving directions.

The wheels 3-6 are preferably provided or mounted to be locked during driving such that they do not thereafter

pivot or swing freely, they may be provided to be locked in certain or optional positions during driving and they may be individually pivotable and/or lockable. Further- more, the wheels 3-6 may be provided for release during driving such that they thereafter can pivot freely.

A wheel setting device 10 schematically illustrated in fig. 1 may be provided or mounted on the chassis 1 for pivoting the wheels 3-6 about the pivot or swinging axles 9 until the wheels 3-6 are set in selected toe-in or toe- -out positions. The wheel setting device 10 may also be provided to lock the wheels 3-6 in said selected toe-in or toe-out positions and to release said wheels 3-6 there- from when desired. The wheel setting device 10 may pre- ferably carry through said functions during driving of the vehicle F.

The wheel setting device 10 illustrated in fig. 1 may consist or four or another number of units. Each such unit may have a wheel 3,4,5 or 6 associated therewith and it may be controlled electronically by means of a central control unit 11 which in turn is controlled by the driver or operator of the vehicle F. Each unit in the wheel set- ting device 10 may comprise a snap-in unit (not shown) which provides for a snap-in fixation or locking of the wheels 3-6 when said wheels are in their toe-in or toe-out positions and which also permits release of the wheels 3-6 from said positions.

The wheel setting device may be designed in many dif- ferent ways and another type of such a device is shown in fig. 7.

Said latter wheel setting device 12 cooperates with two adjacent pairs of wheels FP, BP for simultaneous set- ting of the wheels 3-6 in said toe-in or toe-out positions.

Said latter wheel setting device 12 comprises a set- ting means 13 which is rotatable about a horizontal axis of rotation that is located at right angles relative to the main driving direction HF of the vehicle. The setting means 13 cooperates e. g. through at least a first movement

transfer means 15 with one pair of wheels FP and e. g. through a second movement transfer means 16 with the other pair of wheels BP such that when the setting means 13 is rotated about said axis of rotation 14, the wheels 3,5 and 4,6 respectively, in the adjacent pairs of wheels FP, BP are rotated in opposite directions to their toe-in or toe-out positions. The movement transfer means 15,16 may be wires, rods or similar and they may be mounted such that they simultaneously rotate a wheel 3,5 or 4,6 in each pair of wheels FP, BP instead of both wheels 3,4 and 5,6 in each pair of wheels FP, BP.

The movement transfer means 15,16 may preferably be connected to such parts of the pairs of wheels FP, BP which, seen from the side in a direction FS towards the vehicle F, are situated either inside or outside said vertical plane VP2.

Each wheel 3-6 engages the ground with such downwardly directed parts 17 which are centered with and rotate about the axis of rotation 8. Those portions 18 of the down- wardly directed parts 17 through which the wheel 3-6 shall engage the ground 2, are located in a plane which extends at right angles relative to the axis of rotation 8. Said downwardly directed parts 17 of each wheel 3-6 may be de- signed as annular tires which can be massive or pneumatic.

The tires may also have patterned tread surfaces.

The wheels 3-6 may be suspended on the chassis 1 through different types of suspension devices. One example of such a device is shown in fig. 6 and consists of a yoke 19 which is pivotally suspended on the pivot or swinging axle 9. The yoke 19 is down below provided with a bracket 20 for the wheel 3-6 and the driving motor 7 may also be mounted on said bracket 20.

The chassis 1 may be divided into two chassis mem- bers la and 1b located beside each other. At such an em- bodiment of the chassis 1, one wheel 3 on one pair of wheels FP and one wheel 5 on the other pair of wheels BP are mounted on one chassis member la. The other wheel 4

on said one pair of wheels FP and the other wheel 6 on said other pair of wheels BP are provided on the other chassis member lb. The chassis members la, 1b are pivotally connected to each other through a horizontal pivot or swinging axle 21 which is located between the pairs of wheels FP, BP and which defines right angles with the vertical plane VP1.

It should also be mentioned that the wheels 3-6 can be provided or mounted on schematically illustrated sup- port means 22 which are extensible such that the wheels 3-6 are moved in a direction away from each other, where- by the distance between the wheels 3-6 may be increased.

The support means 22 may be telescopic and they may be mounted such that the wheels are moved in a direction out- wards relative to the chassis 1 about 45° relative to the main driving direction HF from inner positions to outer positions.

Finally, it should be mentioned that the abovementio- ned angle settings may vary within an interval of 1-4° without loss of the desired embodiments.

The device according to the invention is not limited to what is described above and illustrated in the drawings, but may vary within the scope of the subsequent claims regarding its function and construction. As an example of alternative embodiments it should be mentioned that the chassis 1 may comprise more than two pairs of wheels and the chassis 1, the wheels 3-6 and associated members may be of other constructions than those shown.