EP0929436A1

EP0929436A1 - Angle setting device for vehicle wheels

Info

Publication number: EP0929436A1
Application number: EP97945150A
Authority: EP
Inventors: Sture Rönnbäck
Original assignee: Novelty Inventions AB
Current assignee: Novelty Inventions AB
Priority date: 1996-10-11
Filing date: 1997-10-10
Publication date: 1999-07-21
Also published as: WO1998016418A1; SE9603714D0; SE9603714L; SE507494C2; AU4642097A

Abstract

Angle setting device for vehicle wheels which are journalled by a wheel shaft (33), which can be adjusted in different angles. The device comprises a first bearing unit (42), carried by an attachment, which unit is turnably journalled in the attachment around a first rotation axis (A) and which carries a second bearing unit (40), which is turnable in a second rotation axis (B), which deviates from the first said by a first angle (α). The second bearing unit (40) carries the wheel shaft (33) in a second angle (β) between the rotation axis (C) and the second rotation axis (B). Hereby the wheel shaft (33) can be swung in different angles compared to the first rotation axis (A) in the attachment by turning the second bearing unit and simultaneous turning of the latter in the attachment (36).

Description

TITLE :

Angle setting device for vehicle wheels

TECHNICAL FIELD:

The present invention relates to an angle setting device for wheeled vehicles such as road vehicles and crosscountry trucks.

PRIOR ART:

Within the car industry a type of steering arrangement which briefly will be described below, is commonly used. This is based on the fact that, for the steering, the two steerable forward wheels of the vehicle are each swingable around an upright standing wheel spindle, which is turnable during steering, which spindle carries the wheel shaft around which one of the forward wheels rotates. The wheel spindle is in its turn carried by a spring wheel suspension. As a starting point, one can presume that the wheel spindle stands perpendicularly to the road on which the wheels shall run and that the wheel shaft is parallel with the road and in a neutral position for forward movement is perpendicular to the longitudinal direction of the vehicle and that the wheel shafts of both sides are aligned with each other and with the linkage for the steering so that the wheels are tangential to the turning circle of each wheel when cornering. However, it has occured during forward movement especially at high speeds that such an arrangement is not satisfactory with regard to either the stability of the movement or to the wearing of the tyres. Therefore, the steering arrangement of the vehicle is constructed with a number of angle deviations in relation to the normal "angles" at the described theoretical starting point. Such angles are the inclination of the wheels, the camber angle, which shall compensate for the change of the wheel inclination which in most spring systems is created when the spring is compressed, the spindle bolt inclination, KPI, which shall compensate for the case that, for construction reasons, the turning axis of the spindle must be located inside the central plane of the wheel, which compensation sometimes is exaggerated to influence certain road properties, the shaft inclination, the caster angle, which is the inclination backwards or forwards of the spindle bolt and provides a force to bring the wheels back for steering straight forward, "toe-in", which is a setting of the wheel shafts so that the wheels in a neutral steering position are directed forwardly - inwardly in relation to each other to compensate for the tendency towards opposite turning which arises through the use of play in the steering mechanism under force influence during movement. Also, with the linkage system for the steering a compensation is brought about so that the inner wheel rolls along a circle arch having a smaller radius than the outer wheel so that the cornering angle "toe-out" gives each wheel a tangential position in relation to its rolling arch.

To achieve the least wear on the tyres, it is desirable that each wheel stands perpendicular to the road and parallel with the rolling direction of the wheel, which during turning means tangentially to the circle arch of the wheel for its rolling. The said angles are therefore intended to compensate for imperfections in the steering mechanisms and also for forces which arise during movement, especially at high speeds.

However, bringing about a compensation with fixed angles gives optimal results only in certain ideal conditions, whereas in other conditions the compensation will be imperfect or even can work against its purpose. Examples of this are conditions which arise at strong or very low compression of the springs, respectively, on forceful braking or acceleration, in the case of uneven roads and especially during cross-country driving and cornering at high speeds, in the presence of sloping roads or side winds .

Besides the angle setting which, for said reasons, is required for the steered wheels resetting of the wheel angles occurs in these vehicles also for other wheels. Thus, it happens that the wheel angles for the rear wheels are changed during cornering, which can give improved driving properties.

OBJECT OF THE INVENTION:

The object of the invention is to bring about an angle setting device by means of which a compensating setting of the vehicle wheels can be obtained, which gives an ideal wheel setting for low tyre wear and the best driving properties in all conditions and circumstances, even extreme ones. To achieve this the following is required:

- that the wheels are so suspended and journalled that they can be set in all angles within a certain angle range with a directly influenceable mechanism which has sufficiently great strength against those forces which arise in the vehicle;

- that a controlling member is arranged which steers the angle setting mechanism in such a way that the wheels under the present forces and running circumstances will obtain an optimal angle setting with regard to driving properties and tyre wear.

How this is brought about according to the invention in a steered wheel of a vehicle will appear from the following description. DESCRIPTION OF THE FIGURES:

A number of embodiments of the invention are shown in the attached drawings. Further, an embodiment example is given with relation to a steering wheel of a vehicle. The drawings show

Fig. 1 the angle setting mechanism, schematically; Fig. 2 the control member, also schematically; Fig. 3 an embodiment example of an angle setting mechanism; and

Fig. 4 the mechanism substantially according to Fig. 3 but shown with some details added.

PRINCIPAL DESCRIPTION AND PREFERRED EMBODIMENTS: In Fig. 1 the angle setting device denoted with 1 is shown schematically. It consists of the main components an inner bearing 2 by means of which an inner member 3 carrying a bearing called the intermediate bearing 4 for an outer part 5 is turnably journalled along an axis A. The outer part is then journalled in the inner member 2 along an axis B which has an angle a to the axis A. The outer part 5 carries in turn an outer bearing 6 for a shaft 9 to a working member 7, the position of which is indicated with an imagined point 8. The rotation axis for the working member 7, called C, has an angle of β in relation to the axis B. In the figure, the angles α and β are shown to be of equal size. This embodiment is presupposed also in the following description of the preferred embodiment of the invention. When A=B what is gained is that turning in a plane, such as during steering, can occur by means of simultaneous turning with the same rotation angle in both the axes A and B but in opposite turning directions. In the position shown with continuous lines it appears that the geometric relations are such that the axis C can be arranged to constitute an extension of the axis A. The indication point 8 then lies on this axis A-C. It can be said that the bearing 2 is the carrying part of the mechanism and the working member its setting part in different cases. For a steering arrangement this means that the bearing 2 should correspond to the wheel suspension carried by a spring system, whereas the working member is the vehicle wheel. Its angle setting corresponds accordingly to the angle setting of the axis C. This angle setting can be obtained with every angle within a cone having its tip starting from the crossing between the axes A and B and symmetrically located in relation to the axis A. This means that the indication point 8 can be moved to every position of a spherical cap, the central angle of which is equal to 2 β .

This is indicated in Fig. 1 in which the central axis D indicates a turning of the outer part 5 of the bearing 4 by 180° so that the point 8 is displaced outside the central axis A-C of the arrangement. If the part 3 is now turned in the bearing 2, the point 8 will describe a circle around its common central axis A-C. This circular line is the largest possible one with the set dimensions and value of the angle β . By turning the part 5 a smaller angle than 180°, the point 8 may be made to follow a smaller circle and thus every conceivable circle inside the maximum and down to 0 with the position shown in Fig. 1 by continuous lines can be covered. By turning the part 3, also every angle position for the point 8 in every conceivable circle arch can be made. This means that the point 8 can, within the maximal circle line by simultaneous turning of the parts 3 and 5 in their bearings, be made to assume every position within said maximal circle. This means at the same time that the outer part 5 with its central axis C can be made to assume every angle position in relation to the axis A within the imagined cone which is made during rotation of the axis C around the axis A. Every such angle position with corresponding position of the point 8 is accordingly obtained through a certain relation between the turning of the part 3 in the bearing 2 and the turning of the part 5 in the bearing 4, see arrows. In the same way, the track for the movement of point 8 between two positions can be decided by adjustment of the turning relation between the axes A and B and thereby the displacement of the axis C. If, accordingly, the axes A and B, when =β _r are turned with the same angle velocity but mutually in opposite directions, the point 8 will describe a straight line, which means that the working part 7 can only be turned in one plane. By mutually different turning of the two axes, it can be made to swing in all planes.

If the the working part 7, if it is a vehicle wheel, with its axis 9 is to rotate, this will occur in the bearing 6 around the angle-adjustable axis C. If the working part 7 is a driven wheel it must be attached to a driving mechanism for its rotation.

For application to a steering arrangement for vehicles this means that the main movement for the steering movement of the wheels, which means turning in one plane, can be brought about if the turning in the axes A and B is synchronized but directed in opposite directions. The turning of the two steerable wheels does not then have to be made with the same angle movement but here it is possible, by letting the synchronic movements of each wheel have different values, to give the wheels the different angle movement which is required for the inner wheel to follow its rolling circle and the outer its larger rolling circle when the vehicle is turned.

Besides this main movement, also angle movements for said compensation can be made by deviation from the synchronism between the turning in the axes A and B, which shall be explained below.

If, accordingly, the parts 2, 3 and 5 correspond to the principal construction of the steering arrangement and its trimming member for the different setting angles, then the working member 7 can be said to correspond to the steerable wheel itself. Besides a bearing, which is indicated at 6, a braking arrangement and, in the case of front wheel driven cars, a driving arrangement are required. The latter shall allow for angle movement of the central axis C in relation to the axis A when turning occurs along the axis B within the position D for the axis C. This can, as for the known front wheel driven constructions, be brought about by means of a driving joint. Besides the already principally described setting arrangement 1, a control arrangement to bring about the coordinated turnings of the axes A and B is also required. This control arrangement 10 shall allow steering by turning the wheels with different turning angles for the inner and outer wheel when cornering for adaptation to the rolling circles of different sizes. Moreover, they shall allow a change of the wheel setting angles for a first trimming to a starting position and also later changes for adaptation to different driving conditions.

The principles for the control arrangement are shown schematically almost as a block diagram in fig. 2. In this figure the two steerable wheels are denoted with 7 (analogous with the reference numerals in fig 1) and their setting units are denoted with 1, which units principally correspond to the principal which is shown in fig. 1. The axes A, B, C in this figure have also been drawn in fig. 2. Control lines 15 and 16, for turning in the respective axes A, and 17 and 18, for turning in the axes B, are shown drawn to the setting units 1. These movements can be made by turning the steering wheel of the vehicle, which is denoted with 23. This steering wheel is connected to a distribution unit 22 which distributes the movements of the steering wheel to both pairs of control lines 15, 17 and 16, 18. The distribution unit 22 is arranged to give the inner and outer wheel different turning angles when cornering. This difference of the turning angles is dependent on the width of the vehicle, which is constant, and the turning angle of the wheels, which represents the steering direction, and its momentary value will therefore have to be recoupled so that different turning angles are obtained. These units and their functions correspond accordingly to what is obtained by a conventional steering arrangement.

Each pair of control lines can also be influenced by means of angle setting units 24 and 25. As mentioned, the turning of the wheels for steering, which means displacement in one plane, is obtained with the present steering arrangement by turning the axes A and B synchronously in opposite rotation directions compared to each other. The angle setting, however, occurs by means of the turning in the two axes being mutually different. The dividing unit 22 causes said synchronous turning in the axes A and B (however with a different degree of angle turning for each of the two wheels), whereas the angle setting units 24 and 25 cause differentiated influence of the turning of the axes by means of the control lines. The two units 24 and 25 are coordinated with regard to their differentiation effect which, however, does not have to be equal in all situations, by means of a coordination unit 26. This will in turn be influenced to bring about via the units 24 and 25 different angle settings adapted to different factors. These factors may be measured conditions such as compressed springs of the steered wheels, wherein such factors can be sensed by a sensor unit 28. Further, a unit 29 for the starting trimming of the setting angles can be arranged, which setting angles are to be regarded as basic settings. Moreover, a manoeuvre unit 30 may be present which is manually operable by the driver.

Accordingly, the arrangement shown in fig. 2 allows usual steering by turning the wheels in a plane by means of the steering wheel 23. Also, the vehicle may be set for certain starting angles by means of the trimming unit 29 and this can accordingly occur centrally with the unit 29 arranged in an easily accessible place and not, as in a conventional steering arrangement, trimming of each setting member separately. Temporarily, retrimming of the starting angles can occur dependent on different conditions such as the loading down of the vehicle, the condition of the road or side winds during measuring of how these conditions influence the contact of the wheels against the road by means of the sensor units 28. Finally, it is possible to arrange that the driver by means of the operating unit 30 can adapt the wheel setting to special conditions, such as cross-country driving. Alternatively, if a simplified construction is wanted, the sensor unit may be excluded and all retrimming, for example adjustment to the loading of the vehicle, can be left to the driver to carry out by means of the unit 30.

It should also be mentioned here that the steering arrangement according to the invention can be provided with servosupport. According to the usually applied principal, a mechanical connection between the steering wheel and the wheels shall exist so that if the servo effect fails steering may nevertheless be carried out. The setting units 1, the control lines 15, 17, 16, 18 and the division unit 22 should accordingly be able to work mechanically in such a way that for servosupport an outer force can be added. After this principal description the technical application of these principals shall now be described by an embodiment example. In figures 3 and 4 an embodiment is shown in a vertical section with the setting device shown in an enlarged scale.

In fig. 3 the same reference numerals as in Figs. 1 and 2 are used. However, the schematic representation in these figures is replaced by a more technical depiction of one embodiment. The steerable wheel 7 is represented only by a tyre profile and it is suspended on its axle spindle 9, which in the bearing 6 is rotatably journalled in the setting device 1, which in its turn is carried by the part 2 here shown as an axle pipe.

The part 3, which is journalled in the part 2, is here shown as a housing which via the journalling 4, carries the part 5 which also here has the form of a housing. This in turn carries the axle spindle 9 which is rotatable in the bearing 6, here shown as a ball bearing. The axes A, B and C are marked as well as the fixed angle between the axes A and B and the angle β between the axes B and C. a and β are of equal size. The axis C for the axle spindle 9 is shown in a set angle position with A and C aligned with each other. The largest deflection to the opposite direction is marked with the axis D.

Fig. 4 describes the embodiment more technically and with mechanical nomenclature with reference by means of new reference numbers. For the working member, that is the steerable wheel, an axle spindle 33 is shown, on which the wheel with braking arrangements can be mounted non-turnable on the axle spindle. The axle spindle is supported by a bearing 34 and is by means thereof rotatably journalled in the setting arrangement, here 35, which in its turn is supported by a wheel attachment 36. The wheel attachment 36 is resiliently suspended by means of a spring leg 37 and an arm 41. Any other resilient arrangement, for example comprising only slewing brackets, may however be used. A driving shaft 38, journalled at 49, is movably arranged on a not shown gear box. from which a corresponding driving shaft to the steerable wheel at the other side of the vehicle extends. The driving shaft 38 is united via a driving joint 39 with the axle spindle 33 so that the driving connection can be maintained in different turning positions for the axle spindle.

Furthermore, it is shown that the bearing 34 of the axle spindle is carried by an outer housng 40. The housing 40 is journalled via bearing 43 in an inner housing 42 which in turn is journalled via bearing 44 in the wheel attachment 36. The latter journalling represents the above-mentioned turning axis A and the journalling 43 has such an angle (the angle α) that its central axis represents the axis B. The central axle of the axle spindle 33 represents in its turn the axis C and in the neutral position shown in fig 1, which is also shown in fig. 3, it can be seen that the axis C in its turn has an angle with the angle β=a from the axis B. As a result of this, the axis C and the axis A are extensions of each other in this position. To bring about the turning in the axis B, a gear ring 45 is journalled on a hollow shaft 43 in the housing 42 at 48 with its central axis in the axis A. This is in connection with a gear ring 46 which is connected with the bearing housing 40 at a point where the two gear rings which are set at an angle to each other, meet (at the top of fig. 4). The housing 42 is also turnable around the axis A when the angled bearing 43 for the gear ring 46 is brought onto the house 40.

A comparison with Fig. 1 reveals that the said angle settings can be made within the imagined cone which has a tip angle 2β by turning the housing 40 by means of the hole shaft 47 via the gear ring 46 and the gear ring 45 and thereby displacing the bearing 34 for the wheel spindle 33. Hereby, as mentioned above, a turning of the wheel for steering in only one plane means that turning in the axes A and B shall occur synchronously but in mutually opposite directions. (This is valid when the angles and β are of equal size. )

To bring about steering and angle setting by means of the control arrangement 10, turning of the two elements the housing 42 and the hole shaft 47 with its gear ring 45 is accordingly required. The synchronous turning for steering shall then be brought about by a connection with the steering wheel of the vehicle. A non-synchronous turning issues, as mentioned above, from the units 24 and 25. As an example, Fig. 4 shows how the coupling to the wheel setting units can be made. The housing 42 is provided with an arm

50 intended to be connected with one of the driving lines

15/16 in a pair for turning the housing 42. On the hollow axis 47 earring the gear ring 45 a second arm 51 is arranged which shall be connected to the second driving line 17/18 for turning the housing 40.

The embodiment example shown is only one conceivable embodiment. The power transmission between the steering wheel and the setting unit, especially, can be carried out in a number of different ways. Since the setting units must be movable under spring loading in relation to the steering wheel, corresponding movement possibility in the driving lines is required. Besides by means of the arms 50, 51 shown here, this can occur, for example by means of racks and displaceable, bendable rods, made with the driving lines, as bendable shafts, link systems or as, for instance, hydraulic power transmission. The embodiment example is related to steerable vehicle wheels such as the front wheels of passenger cars and lorries. Since the arrangement according to the invention can be constructed for setting of the wheel angles as well as for turning for cornering, this application is presumably the most interesting.

However, there might be a need for setting and resetting of the wheel angles also of the other wheels of the vehicle, in normal cases, accordingly, of the rear wheels of the vehicle. Also here it is possible to gain advantages such as decreased tyre wear by adapting the wheel angles to the spring compression and other factors. It also occurs that vehicles having front wheel steering are provided with a change of the rolling angle for the rear wheel adapted for cornering, which gives a better cornering ability especially at high speeds.

Vehicles having bogies have increase tyre wear in that the bogie wheels, which are set for rolling in a straight line, in bends will slide sidewards towards the road when the bogie is turned. A possibility for resetting of the wheel angles when turning should eliminate this said disadvantage.

Further, there may be special vehicles, such as vehicles for movement along narrow tracks having sharp curves, in which there is a need for steering possibilities of all four wheels.

Even if the arrangement according to the invention is primarily intended for setting and resetting of the wheel angles and for turning the steerable wheels of a road vehicle, the inventive idea also includes further applications where a wheel setting arrangement is required on a vehicle, for example in such cases which have been mentioned above.

Claims

1. Angle setting device for vehicle wheels wherein the wheel is journalled by means of a wheel shaft (9), which is arranged to be set in different angles and thereby give the wheel, for its rolling against a support, an advantageous angle setting with regard to wear and the road-holding properties of the vehicle, c h a r a c t e r i z e d i n that for the support of the wheel shaft (9, 33) and the wheel a preferably spring suspended attachment (2, 36) is arranged on the vehicle in which attachment a first bearing unit (3, 42) is arranged turnably around a first rotation axis (A) , which first bearing unit carries a second bearing unit (5, 40) which is turnable in the first bearing unit along a rotation axis (B), which deviates from the rotation axis (A) for the first unit with a first angle (α), which second bearing unit (5) carries the wheel shaft (9, 33) in a second angle (β ) between the rotation axis (C) of the wheel shaft and the rotation axis (B) for the support of the second bearing unit in the first bearing unit, whereby the rotation axis (C) of the wheel shaft can be swung in different angles in relation to the rotation axis (A) of the first bearing unit by turning the second bearing unit in the rotation axis (B) for its support in the first bearing unit and thereby in its more or less angle deviated position in relation to the rotation axis (A) of the first bearing unit can be moved in a circular track by turning the first bearing unit (3) in its attachment (2) so that by simultaneous turning of the first bearing unit in the first rotation axis (A) and the second bearing unit in the second rotation axis (B), the wheel shaft with its rotation axis (C) can be set in all angles within a conical volume the tip of which starts from the crossing point between the rotation axis (C) of the wheel shaft and the rotation axis for the support of the second bearing unit in the first bearing unit and the tip angle of which is determined by the size of said second angle (β) between the two last- mentioned rotation axes (C, B) whereby the vehicle is provided with a control arrangement (24, 25, 26) arranged for simultaneous turning of the first and the second bearing unit so that for the forward movement of the vehicle adapted angle settings are obtained for the vehicle wheels provided with the angle setting arrangement.

2. Angle setting device according to claim 1, c h a r a c t e r i z e d i n that the control arrangement (24, 25, 26) is connected to units (28, 29) arranged for sensing outside factors such as the loading of the vehicle, speed, the inclination of the road and the side wind, for example, and arranged to set the wheel angles via the control arrangement for compensating of said factors when the vehicle is moved forwards.

3. Angle setting device according to claim 1 or 2, c h a r a c t e r i z e d i n that it is arranged on wheels which are steerable for cornering and that the control arrangement (24, 25, 26) is coupled to an operating wheel (23) or similar steering member for turning of respective wheel shafts, and thereby wheels, in the intended angle for the curves.

4. Angle setting device according to claim 1, 2 or 3, c h a r a c t e r i z e d i n that both said angles (α, β) are mutually of equal size whereby the rotation axis (A) of the first bearing unit and the rotation axis (C) of the wheel shaft in a certain turning position between the first and second bearing unit can be made to form a straight line.

5. Angle setting device according to claim 3 and 4, c h a r a c t e r i z e d i n that for turning of respective wheel shafts (9, 33) for cornering, the control arrangement (24, 25, 26) is arranged to turn the first and the second bearing unit (3, 42 - 5, 40) with the same angle, the size of which is determined by the angle size of the operating wheel (23) or similar steering member with the turning of the two bearing units in opposite directions for displacing the wheel shafts substantially in one plane.

6. Angle setting device according to any one of the preceding claims, c h a r a c t e r i z e d i n that said fastening (2) is a wheel suspension unit (36), that the first bearing unit (3) is a first housing (42) and that the second bearing unit (5) is a second housing (40), in which the wheel shaft (33) is suspended, and which housing is supported in the first housing in said rotation axis (B) with the angle ( β ) in relation to the rotation axis (A) of the second housing for its support in the wheel suspension unit (36) and that in the first housing (42) an inner shaft (47) having a cog wheel (45) is suspended concentrically to its rotation axis (A) in the wheel suspension unit, which cog wheel is in engagement with a corresponding cog wheel (46) on the second housing (40) and within the first housing (42) with the two cog wheels forming a conical gear which allows turning of the second housing (42) by turning the inner shaft (47), and that for said simultaneous turning of the first and the second housing members (50, 51) for coupling to the control arrangement (24, 25, 26) are arranged at the first housing (42) and the said inner shaft (47) whereby the two coupling members can be turned around axes concentric to the rotation axis (A) of the first housing.

7. Angle setting device according to claim 6, c h a r a c t e r i z e d i n that it is arranged on a steerable and drivable wheel wherein the inner shaft (47) is arranged as a hollow shaft and is run through by a driving shaft (38) arranged inside it, which by means of a driving gear (39) is connected to the driving shaft (33) housed in the second housing (40).