Patent Publication Number: US-2007114074-A1

Title: Wheel supporting device for vehicles

Description:
AREA OF INVENTION  
      The present invention is of a supporting system for vehicle wheels.  
     TECHNICAL STATUS  
      A wheel supporting system must be able to transfer power to the wheel while, at the same time, allowing the wheel to move in relation to the vehicle chassis, partly vertically through spring action and partly, at least for two wheels, allowing the wheels to be turned round a vertical axle in the steering action. All these requirements are generally fulfilled by the use of torsion axles with ball links or steering rods. In order to allow the axle extension lines of the wheels engaged in the steering action to cross each other at one and the same point, the pole, the wheels must be connected to each other by a parallel rod. This is necessary to enable the wheels to roll without skidding in a road bend. To enable the wheels to move vertically in spring action while retaining their track distance various types of linking rods and steering rods are used in the supporting.  
      Proposals have been made for so-called hybrid vehicles in which the secondary effect derives from an electric motor jointly connected to one or two pairs of wheels. In this system, too, the moment is transferred to the wheels by means of torsion axles with differential gears.  
      Further, there are proposals for electric, pneumatic or hydraulic wheel motors in which at least the torsion axles are replaced with flexible cables or tubes, but in these cases, too, the wheels are turned when steering by steering rods with ball links.  
      When the vehicle is being driven in rough country there is a need to increase the road clearance. When driving on smooth roads a low clearance may be allowed and at high speed a low clearance is desirable to keep the centre of gravity low. There are systems on the market which fulfil these requirements. It may also be the case that the front wheels and the rear wheels should be at different distances from the road surface depending on the load. It may even be desirable that one side is higher than the other, that is to say, the vehicle need to be able to bank or lean in a road bend. It is essential that clearance adjustment can be carried out for each of the four wheels individually.  
     PRINCIPLE OF INVENTION  
      The present invention eliminates the drawbacks of the supporting systems known at present and fulfils the requirements mentioned above, which can be realized through the characteristics mentioned in the patent claims. It also applies to the case where the driving wheels contain individual wheel motors of an electric, pneumatic or hydraulic type. Its main advantage is that it enables all the wheels to take up a transverse position, which drastically simplifies parking. However, the invention may also be applied in cases where the wheels are driven mechanically by a ball link, although in such cases a 90 degrees turning of the wheels is not possible. 
    
    
      The basic principle is shown in the  FIGS. 1-4  where:  
       FIG. 1  shows a side section of the wheel supporting according to the present invention. The figure left of the centre line shows the wheel supporting when the wheel is not under pressure or the spring is in an open position and with the lowest possible clearance. The figure shows the wheel right of the centre line when it is under maximum pressure and the spring is depressed, and the chassis is raised to the highest possible clearance position.  
       FIG. 2  shows a horizontal section of the wheel supporting of  FIG. 1 .  
       FIG. 3  shows a transverse section of the vehicle with an electric wheel motor.  
       FIG. 4  shows the variant with a mechanically driven wheel. Different designs and applications appear in  FIGS. 5-19 , in which:  
       FIG. 5  is a longitudinal section of the vehicle with a variant of the wheel mechanism in which the spring action is performed by a mechanical spring placed in the centre of the mechanism. Left of the centre line, the spring is shown in its unloaded state with the wheel system set for minimum clearance. To the right in the figure the system is shown with the spring depressed with the mechanism set for maximum clearance.  
       FIG. 6  shows a horizontal section of the mechanism.  
       FIG. 7  shows a longitudinal section of a variant of the wheel mechanism in which a gas-hydraulic spring at the centre of the vehicle is used to perform the springing action.  
       FIG. 8  shows a section of the upper part of a system in which an electrically powered motor-driven mechanical screw jack is used as a movement device.  
       FIG. 9  shows a longitudinal section of a mechanism in which, instead of the cassette boxes referred to above, link rods are used to guid the spring action and the lifting action to adjust the clearance.  
       FIG. 10  shows several horizontal sections and views of the mechanism in the previous figure.  
       FIGS. 11-15  show how the wheel mechanism can be fixed to a bottom plate on the vehicle chassis. The right rear wheel is shown in a transverse position and in  FIG. 13  the left front wheel is set for high clearance.  
       FIGS. 16-18  show details of how the wheel mechanism is mounted on, and fixed to, the bottom plate.  
       FIG. 19  shows the air flow around a vehicle. 
    
    
      The aim of the present invention is partly to enable the wheel to have a spring movement range of about 80 mm and partly to enable the chassis to be raised by about 100 mm in relation to the wheel axle. This is possible as the wheel  1  is fixed to the bottom of a box  2 , which is vertically movable inside a second box  3 , which is inside a third box or cassette  4 . The first box  2  is connected to the second box  3  by springs  5  and a shock absorber (not shown) in order to give the wheel springing action on a rough road surface.  
      The second box  3  and the cassette  4  are connected to the movement mechanism  6  by mechanical jacks or air or oil cylinders. Since the cassette  4  is fixed to the vehicle chassis by ears, the chassis can be raised or lowered by activating the movement mechanism  6 . In order to ensure that the different boxes move with the minimum degree of friction and to eliminate the risk of jamming, they are controlled by ball guides  8 .  
      In  FIG. 1  to the left of the centre line is shown the wheel supporting when the wheel is not under pressure or the spring is not depressed and the clearance is at the lowest setting possible. To the right of the centre line in the same figure is shown the wheel mechanism when the wheel is under maximal pressure, the spring is depressed and the chassis raised to maximum clearance. The aim is also to enable the wheel to turn at least  45  degrees in one direction and 90 degrees in the opposite direction round the vertical central axle of the wheel. This is possible as the axle of the wheel  9  is supported by a fork  10  with one or two brackets ( 10   a,    10   b ) from a disc  11 , which, together with its stub axle  12  and ball bearings  12 ,  13 , is journalled in the inner box  2  mentioned above. One  13  of these bearings is of a type that can absorb axial forces and moments at right angles to the stub axle  12 . The stub axle of the wheel fork  10  has a worm wheel  15 , interacting with the screw  16  in a worm gear  17 . The worm gear  17  is driven by a “Can”-controlled step motor  18 , which turns the wheel  1  by steering impulses from the driver&#39;s seat. For reasons of safety, these steering impulses must be regressive in relation to the steering wheel movements and follow a programme in which the steering radius and the speed of the vehicle are parameters. It is taken as understood that the wheel can be turned either by a pneumatic or a hydraulic control system. The design described above can also be used in cases where the wheel is driven mechanically by means of a universal joint  37 ,  FIG. 4 , but the turning ability of the wheel is limited by the angular adjustment range of the universal joint.  
      A supporting system according to the present invention may easily include sensors for factors of importance for the safe handling of the vehicle. The turning angle of the wheels alfa can be derived from the steering impulses going to the positioning motor  18 . The sideways pull on the vehicle in bends or the centrifugal force Fc can be gauged by an accelerometer or pressure sensor in one of the fixing bolts  7 . The weight of the vehicle Fg can be derived from the impulses going to the mechanism for raising and lowering the vehicle  6  and this movement h can be gauged simply with a position sensor in the same mechanism.  
     DESIGNS ACCORDING TO PRINCIPLE  
      A detailed description of the present invention with references to the figures:  
       FIGS. 5 and 6 : The vehicle wheel  1  is supported by a fork  10  with one  10   a  or two  10   b  brackets from a disc  11  with an axle stub  12 . The axle stub  12  is journalled with ball bearings  13 ,  14  in a gear box  17 . The gear box  17  is built into a box  2 , which is vertically movable within a box  3 . Its mobility is facilitated by ball guides  8  placed in three or four of the corners of the box. The boxes can be made quite rectangular with four corners, but also, as is shown in  FIG. 6 , with five corners, so that one short side is wedge-shaped. The stub axle  12  is hollow, so that a spring coil  19  can be placed inside it which at the lower end rests on the fork disc  11  via a journalled washer  11   b  and at the top end pushes against the ceiling of the box. The spring  19  can thus absorb and damp shocks from the wheel caused by bumps in the road.  
      Mounted on the stub axle  12  is the worm wheel  15 , which, together with the worm screw  16 , is part of the worm gear  17 , which makes it possible, by means of an electric motor  18 , to turn the wheel fork  10  in order to steer the vehicle. If faults develop in the electrical system of the positioning motor  18 , in an emergency, the wheel fork can be steered mechanically by connecting an axle with a ball joint from an emergency steering wheel to a spare axle  16   b  on the angular gear of the positioning motor.  
      The box  3  mentioned above is movably mounted in a cassette  4 , which is fixed by means of ears and screws  7  to the sub-frame of the vehicle. Here, too, mobility is facilitated and controlled by ball guides  8  in the corners of the boxes. A cylinder  20  containing a piston with a rod  21  is fixed to the roof of the box. Thus the cassette  4  along with the chassis, which are fixed together, can be raised in relation to the wheel axle by the induction of hydraulic oil or compressed air through a duct  22 , which is shown to the right of the centre line of the section in  FIG. 5 . In order to prevent the introduction of sand and other impurities into the gaps between box  2 , box  3  and cassette  4 , strip seals of the scraping—tongues type are applied at their lower edge.  
      A variant of a spring coil system is shown in  FIG. 7 . Here the cylinder  20  mentioned above is shaped like a piston  23  on the outside, which moves in a second cylinder  24 , which ,in its turn, functions as a piston moving inside a third cylinder  25 , extending from the roof of the box  3 . The space on either side  26 a,  26 b of the first piston  23  is filled with hydraulic oil, which can flow through nozzles in the piston, the area of the nozzles determining the speed of the motion. The upper space between the latter piston  24  and the cylinder  25  is filled with inert gas.  
      Oil and gas are replenished through connections and ducts not shown in the figure.  
      As the functioning of this gas-hydraulic spring is well known from other contexts, for example the undercarriage of aeroplanes, it is not further described here. Gasket rings are inserted to tighten the pistons in the normal way.  
      In  FIG. 8 a  variant is shown of the wheel mechanism in which the piston  21  described in  FIG. 5  is replaced with a screw  28 , which is turned, via an angular gear  29 , by an electric positioning motor  30 . The screw  28  moves in a nut  31  which is fixed inside the cylinder  20  mentioned above, which is fixed in the box  3 . When the screw  28  turns, the cassette  4  and, together with it, the whole chassis are raised.  
      In the design of the mechanism according to  FIG. 9 , the worm gear box  17  is connected to a disc  32  by linking arms  33  on either side and this disc  32  is, in its turn, linked by similar arms to a frame  35 , which is fixed to the chassis  37  by vibration-absorbing screws  36 . The spring coil  19  described above in  FIG. 5  is fixed to the disc or the cylinder  25  in  FIG. 7 . The cylinder  20  referred to above and its piston are also included in the design.  FIG. 9 , which presents a sideways view of the mechanism, shows, to the left of the central line, the mechanism with the spring coil unloaded and set for the lowest clearance. To the right of the centre line in the same figure the mechanism is shown under maximum pressure with the chassis raised for maximum clearance.  FIG. 10  shows the same mechanism seen from above or in several different horizontal sections.  
      In the present design the frame  35  corresponds to the cassette  4  and the plate  32  corresponds to the box  3  and the gear box  17  corresponds to the box  2  in the previous versions of the design. An advantage of the invention is that the chassis can be made as a plane bottom plate to which the cassette box  4  can be fixed. This is described in more detail in  FIGS. 11-15 . The bottom plate consists of outer longitudinal hollow girders  38  and central hollow girders  39 , which are held in position by a smooth top plate  40 , which is the floor of the vehicle cabin, and an outer corrugated bottom sheet  41  with longitudinal grooves. The corrugation of the bottom sheet has an arching profile  42  from the ground a 1 m radius R between the girders. This causes the longitudinal air currents to develop between the plate and the ground, which helps the vehicle to stay on course. The space between the smooth top plate and the corrugated bottom plate can be filled with light foam material in order to stabilize the plates and provide heat and noise insulation.  
      Since the supporting system just described lacks steering rods and power axles (for electric wheel motors), the sub-frame with the supporting mechanism in combination with the bottom sheet will have no interfering elements which can catch on bumps in rough ground. In addition, there is no air turbulence under the vehicle and its total air resistance will be reduced, which makes for much improved running economy at high speed.  
      In order to improve the air flow between the wheels and the bottom plate, the wheels can be surrounded by screens, which are shown in detail in  FIGS. 16-18 . On the inside of the wheel, against the fork, a half-moon shaped plate can be mounted, which changes into a mudguard  44  at the upper half of the wheel. A slightly upwards arching torsion disc, positioned between the wheel and the inner wall of the wheel house  45 , follows the turning motion of the wheel. In this motion the disc  46  packs tightly against the wall of the wheel house  45  with an elastic tongue  47 . The disc also  46  helps to maintain an even air flow in the wheel houses and around the wheels as well as prevents mud from splashing on the inner walls of the supporting mechanism. All four supporting mechanisms can be of identical design whether for electric power and four-wheel steering or each pair of wheels identical with two-wheel mechanical drive or two-wheel steering. The fixing procedure to the bottom plate for two wheels is the same as for four wheels and is easily performed when the vehicle is jacked up by pushing the mechanism up from below towards the brackets  50  and  51 , to which it is then fixed with vibration-absorbing bolts. Conversely, the wheel units can be easily dismantled for service. Checking and maintenance can then be carried out at special service stations which have facilities for easy access to all vital parts, such as tyres, wheels and brakes, wheel motors and steering systems.  
      Another advantage of the supporting system according to the present invention is that the steering action takes place by means of electric signals in cables, which makes a mechanical steering wheel and a steering column superfluous. The space in front of the driver&#39;s seat  43  is therefore free both at seat level and, because of the bottom plate just described, also at foot level. Hence the driver&#39;s seat can be designed to give the driver a choice of three positions in which to sit: on the left, as in vehicles for right-hand traffic, in the centre, which is the safest position, and on the right, as in vehicles for left-hand traffic. Thus the driver can sit where he feels safest and most comfortable. This system reduces the risk of dazzling in darkness if the driver, in right-hand traffic, sits on the right or furthest away from the meeting light beam. Similarly, the risk of parking accidents is reduced if the driver, in right-hand traffic, sits on the right and is able to get out of the car onto the pavement to the right—not to the left into the flow of the traffic! 
      A further advantage of the present invention is that the front and the rear of the car can be set at different elevations. This may be necessary to compensate for an uneven load distribution, but also to control the air flow round the vehicle. A wheel supporting system and a vehicle bottom designed according to the present invention ensures an even air flow free from interference around the vehicle ( FIG. 19 ). This air flow will provide a downward pressure which helps to keep the vehicle on the road, especially at high speed, provided the inclination of the bottom, expressed with the angle of incidence of the air v, is correct.