Abstract:
A device for use in a vehicle steering system, said device comprising at least one actuator affixed to a wheel linkage of at least one wheel of said vehicle steering system. The actuator comprises a rotation assembly engagable with a first wheel linkage segment, an electric motor for actuating movement of the rotation assembly via a gear box and one or more sensors integrally contained in the actuator for sensing one or more parameters selected from the group consisting of force, speed, turns and rotation. Rotation of the rotation assembly actuates linear movement of said first wheel linkage segment into and out of said actuator to thereby adjust one or more wheel parameters of said at least one wheel, and wherein said one or more sensors provide real time data to an actuator control unit integral to said actuator to self-adjust rotational parameters of said rotation assembly.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for adjusting vehicle steering and a method of using said device to control and adjust vehicle steering. 
     BACKGROUND OF THE INVENTION 
     Vehicle steering has traditionally comprised of adjusting the vehicle wheels&#39; toe angle, caster or camber or all three to direct travel of the vehicle. Camber caster, and toe are typically adjusted during maintenance of a vehicle. Toe angle is typically also constantly changed during driving by turning of the steering wheel, which motion is typically translated through the steering column to a steering gear box or steering rack that changes the angular position of the wheels. 
     Toe angle can affect steer angle as the suspension system is compressed or extended from straight position. These changes in toe angle can enhance steering or it can detract from vehicle performance depending on whether the wheel&#39;s toe angle follows the desired direction of travel or not. In straight ahead driving it is typically desirable for all four wheels to have a slightly toe-in orientation. In braking it is preferably that the front suspension be in compression and the rear suspension be in extension; this tends to result in a toe-out angle for all wheels. To correct this toe-out orientation, an active adjustment needs to be made to all wheels. For improved traction and steering stability while braking in a turn, it is desirable to have some wheels toe-in while other wheels toe-out. 
     In some cases, it may be desirable to adjust wheel toe angle of all four wheels to match one another, to improve turning fidelity and also to reduce drag and improve fuel consumption. In other cases, it may be preferably to adjust the toe angle of the rear or front wheels to oppose one another, for example to enhance braking speed and effectiveness. Adjustment and control of both of these aspects of the wheels&#39; orientation are important to stable driving in a straight direction, as well as accurate turning. 
     U.S. Pat. No. 5,143,400 teaches an apparatus for active toe adjustment in which a complex system of measuring devices are used to sense vehicle motion or toe angle relative to each wheel. This data is then conveyed via a computer to a separate system comprising mechanical screw actuators and optical encoders, to then make secondary toe angle corrections. 
     U.S. Pat. No. 7,873,440 teaches an apparatus for controlling toe angle of a pair of wheels such that the wheel toe angles match one another. The apparatus includes an actuator and a separate sensor on each of only two wheels on a vehicle. The system is not designed for independent movement of all wheels of a vehicle to individual toe angles. 
     A need therefore exists in the art for a convenient and accurate system of vehicle toe angle and camber adjustment. 
     SUMMARY OF THE INVENTION 
     A device for use in a vehicle steering system, said device comprising at least one actuator affixed to a wheel linkage of at least one wheel of said vehicle steering system. The actuator comprises a rotation assembly engagable with a first wheel linkage segment, an electric motor for actuating movement of the rotation assembly via a gear box and one or more sensors integrally contained in the actuator for sensing one or more parameters selected from the group consisting of force, speed, turns and rotation. Rotation of the rotation assembly actuates linear movement of said first wheel linkage segment into and out of said actuator to thereby adjust one or more wheel parameters of said at least one wheel, and wherein said one or more sensors provide real time data to an actuator control unit integral to said actuator to self-adjust rotational parameters of said rotation assembly. 
     A method is further provided for adjusting vehicle steering. The method comprises providing at least one actuator to a wheel linkage of at least one wheel of said vehicle said actuator comprising, a rotation assembly engagable with a first wheel linkage segment, an electric motor connected to the rotation assembly via a gear box and one or more sensors integrally contained in the actuator, rotating the rotation assembly to actuate linear movement of said first wheel linkage segment into and out of said actuator to thereby adjust one or more wheel parameters of said at least one wheel and relaying real time data from said one or more sensors to an actuator control unit integral to said actuator to self-adjust rotation of said rotation assembly. Data from collected by said one or more sensors is selected from the group consisting of force, speed, turns and rotation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view of a first embodiment of the present invention; 
         FIG. 2  is a cross sectional view of a second embodiment of the present invention; 
         FIG. 3   a  is a cross sectional view of a first embodiment of the rotation means of the present invention; 
         FIG. 3   b  is a cross sectional view of a second embodiment of the rotation means of the present invention; 
         FIG. 3   c  is a cross sectional view of a third embodiment of the rotation means of the present invention; 
         FIG. 4   a  is a detailed cross sectional view of a first embodiment of a force sensor of the present invention; 
         FIG. 4   b  is a detailed cross sectional view of a second embodiment of a force sensor of the present invention; 
         FIG. 5  is a detailed cross sectional view of a first end of the actuator housing of the present invention; 
         FIG. 6   a  is a detailed cross sectional view of a first embodiment of a second end of the actuator housing of the present invention; 
         FIG. 6   b  is a detailed cross sectional view of a second embodiment of a second end of the actuator housing of the present invention; 
         FIG. 6   c  is a detailed cross sectional view of a third embodiment of a second end of the actuator housing of the present invention; 
         FIG. 7   a  is a detailed cross sectional view of a first embodiment of the arrangement between the first tie rod segment and the second tie rod segment of the present invention; 
         FIG. 7   b  is a detailed cross sectional view of a second embodiment of the arrangement between the first tie rod segment and the second tie rod segment of the present invention; 
         FIG. 7   c  is a detailed cross sectional view of a third embodiment of the arrangement between the first tie rod segment and the second tie rod segment of the present invention; 
         FIG. 7   d  is a detailed cross section view taken along line D-D of  FIG. 7   b;    
         FIG. 8  is a schematic plan view of a first embodiment of a vehicle suspension system incorporating the system of the present invention; 
         FIG. 9  is a schematic plan view of a second embodiment of a vehicle suspension system incorporating the system of the present invention; 
         FIG. 10  is a schematic elevation view of one embodiment of the present invention, for use in wheel camber or castor adjustment and control; 
         FIG. 11  is a schematic elevation view of one embodiment of the present invention, for use in vehicle height adjustment and control; and 
         FIG. 12  is a schematic diagram of one method of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides a wheel actuator for a vehicle that is electronically powered and self-adjusting. The present actuator can be affixed to any wheel linkage of each wheel to adjust such parameters as toe angle, camber, caster and vehicle height. The wheel linkage may be a steering linkage such as a tie rod, or a suspension linkage such as a strut, control arm or any other part of that connects the wheel to the vehicle suspension system or to the vehicle steering system. 
     The present actuators include integral force sensors to sense forces acting on a particular wheel and to detect changes in driving mode. Information from the force sensors is then fed back to the actuator to make self-adjustments in actuation to achieve the desired toe angle, vehicle height, wheel caster or wheel camber. 
     With reference to the Figures, one embodiment of the present actuator  2  is shown. The present actuator  2  is preferably an electrically driven, mechanical screw type or ball bearing type actuator that can be affixed to any and each modified wheel linkage of a vehicle wheel. For the purposes of toe angle adjustment, the present actuator  2  can be affixed around a modified tie rod having a first tie rod segment  4  connected to a wheel  50 , and a second tie rod segment  6  that surrounds the first tie rod segment  4  at one end and is connectable to the vehicle suspension  56  or vehicle body  58  at the other end. At least a portion of the first tie rod segment  4  is preferably threaded  8 . It would be well understood by a person of skill in the art that for adjustment and control of other wheel parameters, the actuator  2  may be affixed to any wheel linkage of any wheel of the vehicle, furthermore, one or more actuators may be affixed to one or more wheel linkages of a wheel. 
     The actuator  2  comprises an actuator housing  10  that contains all of the components of the actuator  2  and receives the first tie rod segment  4 . The actuator housing  10  can be affixed to the second tie rod segment  6  in any number of means including threading, welding, friction fit. Most preferably the actuator housing  10  is threadably connected  38  to the second tie rod segment  6 , as illustrated in  FIG. 5 , to thereby advantageously allow the actuator  2  to be removed if desired. Any number of arrangements can be made to allow for linear movement of the first tie rod segment  4  within the actuator housing  10 , some of which are illustrated in  FIGS. 6   a  to  6   c , including a bushing connection  40  as shown in  FIG. 6   a , or a busing  40  combined with a seal  42  as illustrated in  FIG. 6   b , to keep debris from entering the actuator housing  10 .  FIG. 6   c  illustrates a bushing connection  40  in combination with a cover  44  to prevent ingress of debris into the first tie rod segment  4 . 
     A rotation assembly  12  engages threaded portion  8  of the first tie rod segment  4  and is powered by means of an electric motor  14  connected via a gear box  16  to the rotation assembly  12 . The electric motor  14  is controlled by an actuator control unit (ACU)  18 , which are well known in the art. The ACU  18  receives data from the force sensors as well as from the vehicle&#39;s active suspension module  52 . In one embodiment, depicted in  FIG. 1 , the electric motor  14 , gear box,  16  and ACU  18  may be housed on the actuator  2  and more preferably covered by a cover  22  to prevent ingress of dirt and dust into these systems. In an alternate embodiment, illustrated in  FIG. 2 , the electric motor  14 , gear box,  16  and ACU  18  may be located separately to actuator  2  and connected thereto by means of a cable  24 . 
     With reference to  FIGS. 3   a ,  3   b  and  3   c , the rotation assembly  12  of the present invention can be of any form that successfully translates rotation force from the gear box  16  to the threaded portion  8  of the first tie rod segment  4  to result in linear movement of the first tie rod segment  4  into or out of the actuator housing  10 . Such linear movement of the first tie rod segment  4  results in angling of the wheel  50 . In most cases, a first gear  26  is connected to the gear box  16  and translates rotation force from the gear box by a number of mechanisms. For example,  FIG. 3   a  shows the translation of rotation from first gear  26  via a belt  28  to a second gear  30  around the first tie rod segment  4 . The internal surface of the second gear engages the threaded portion  8  of the first tie rod segment  4  to thereby linearly move the first tie rod segment  4  either into or out of the actuator housing  10 .  FIG. 3   b  shows an example in which translation of rotation from the first gear  26  is via a one or more corresponding third gears  32  to the second gear  30  around the first tie rod segment  4 .  FIG. 3   c  shows an example in which rotational force is directly transferred from the first gear  26  to the second gear  30  around the first tie rod segment  4 . 
     Linear movement of the first tie rod segment  4  can be accommodated in the second tie rod segment  6  by any number of means, some of which are illustrated merely by example in  FIGS. 7   a  to  7   c .  FIG. 7   a  illustrates a simple relationship in which sufficient annular space is provided between an outer diameter of the first tie rod segment  40  and the second tie rod segment  6  to accommodate such movement. In  FIGS. 7   b  and  7   d , a non-circular bolt and bolt hole arrangement  46  still allow for linear movement of the first tie rod segment  4  in the second tie rod segment  6 , while preventing any rotation of the former in the latter, for example in the case of any form of breakage in the actuator that might cause the first tie rod segment  4  to spin. In  FIG. 7   c , a bolt and bolt hole in conjunction with a bushing  48  to prevent possible wear of either the first tie rod segment  4  or the second tie rod segment  6 . 
     One or more force sensors  20  are preferably incorporated directly within the actuator  2  of the present invention and located adjacent the rotation assembly within the actuator housing  10 . The force sensors  20  of the present invention can be of any type well known in the art to detect compressive and/or tensile forces or pressures. These force sensors  20  are more preferably arranged in pairs. The force sensors  20  detect compressive or tensional forces between the actuator body  2  and the rotation assembly  12 ; and between the second tie rod segment  6  and the rotation assembly  12 . The compression or tension sensed by each force sensor  20  provides information on whether or not a particular wheel is resisting movement in the direction of desired steering. The force data can also provide an indication of wheel problems such as a loose or flat tire, which will lead to rapid fluctuations in forces or a force reading that is outside of normal steering operation. In this capacity, the present actuator can also provide suspension diagnostics information. 
     Force data collected from the force sensors  20  is returned to the ACU  18  and preferably also sent by the actuator  2  to the vehicle&#39;s controller area network (CAN) bus and to the vehicle&#39;s active suspension module  52 . 
     The force sensors  20  of the present invention may be of any type known in the art to sense compressive and tensional forces. As shown in  FIGS. 1 and 2 , preferably the force sensors  20  of the present invention are provided as a pair of force sensors  20  on either side of rotation assembly  12 . Most preferably the force sensors  20  are placed on either side of the rotation assembly  12 . With reference to  FIGS. 4   a  and  4   b , two preferred embodiments are shown for protecting the force sensor  20  from wear, friction, undesirable movement or breakage resulting from rotational movement of the rotation assembly  12 .  FIG. 4   a  illustrates a thrust ball bearing  34  placed between the rotation assembly  12  and the force sensor  20 , and  FIG. 4   b  illustrates a needle bearing  36  placed between the rotation assembly  12  and the force sensor  20 . 
     One or more Hall sensors  54  are preferably also provided within the actuator  2  of the present invention, more preferably adjacent the gear box  16  and within the actuator cover  22 . Alternately, as depicted in  FIG. 2 , the Hall sensors  54  may be located with the electric motor  14 , gear box,  16  and ACU  18  separate to actuator  2  and connected thereto by means of a cable  24 . Such Hall sensors  54  can be used to detect and determine parameters related to the gear box  16  including speed, rotation and number of turns of the gear box  16 . Such data can then be fed back to the ACU  18  to determine if the actuator  2  is making proper adjustments to the wheel. While Hall sensors  54  are specifically referred to herein, it would be understood by a person of skill in the art that any number of other sensors that also detect rotation speed and act as turns counters could also be used without detracting from the scope of the present invention, including optical sensors, rate gyros and gyroscopes. Hall sensors are particularly preferred because they are not ill-affected by vibration or environmental contaminants. 
     The Hall sensors  54  of the present invention differ from conventional position sensors often used in the art, which simply provide positional data relative to an inputted initial position. In such cases, the sensors must always be calibrated to ensure that the initial position reading is accurate. No such initial adjustment is required to calibrate the present force sensors  20  or Hall sensors  54 . Furthermore, the integration of the present force sensors  20  and Hall sensors  54  into the present actuator  2  provides more accurate wheel  50  and gear box  16  data than that which could be collected by separate or stand alone sensor systems. 
     With reference now to  FIG. 8 , a conventional set up of the present actuators on a vehicle is shown in which the steering wheel communicates with the vehicle&#39;s suspension  56  to direct steering of the vehicle.  FIG. 8  illustrates a front wheel drive vehicle in which the rear wheels are connected to the vehicle body  58  through any standard linkage. The present actuators  2  are small enough that they can be affixed to each of the wheels  50  of the vehicle. Since the present actuators have integral force sensors  20  and preferably also integral Hall sensors  54 , the present actuators  2  can receive real-time data on wheel position, speed, resistance to turn as well as gear box  16  parameters. This data is then fed back to the ACU  18  and used to self-adjust the actuation of the first tie rod segment  4  to provide continual assessment an adjustment of vehicle height, toe angle, caster or camber. 
     Data from the force sensor  20  and Hall sensor  54  can also optionally be sent by the actuator  2  to the vehicle&#39;s active suspension control  52  to be compared with data from all other wheels  50  to ensure all four wheels  50  are being adjusted as desired in relation to one another. Data can also be sent back to the actuator  2  from the active suspension control  52 . Wheel data provided to the active suspension control  52  can also be sent to other vehicle systems, including but not limited to anti-lock braking systems (ABS), the engine, air bags and other safety systems, parking assist systems, vehicle transmission and navigation systems, to inform and adjust such systems. 
     With reference to  FIG. 9 , an alternate steering concept is illustrated, often referred to as ‘steering by wire.’ In steering by wire, electronics instead of hydraulic or mechanical systems are used to control steering of the vehicle. As such, a conventional steering wheel connected to the front wheels by a steering column would be replaced electronic signals sent to a steering motor  60  and actuate steering and turning of the wheels  50 . In such cases, steering commands can be provided by any number of devices  68  including but not limited to a steering wheel, a joystick, a computer screen interface, a navigation system, buttons etc. via a steering module  62  to the steering motor  60  and vehicle suspension  56 . In steering by wire, it is possible for the steering module  62  to command not only a steering motor  60  on the front wheels, but also on the rear wheels, thereby providing all wheel steering control of the vehicle. 
     The present actuator  2  can advantageously be used in a steering by wire arrangement. One or more of the present actuators  2  can be applied to one or more wheel linkages of each of the wheels  50  to provide data not only on the front wheels, but also to the rear wheels. The integral force sensors  20  and Hall sensors  54  of the present actuators  2  provide real time wheel  50  and gear box  16  data to the actuator  2  to provide a constant assessment and adjustment of the wheel toe angle. The present actuators  2  can additionally communicate force sensor  20  and Hall sensor  54  data with the steering module  62 , via the active suspension control  52 , to provide real time wheel  50  and gear box  16  data to inform the steering module&#39;s  62  commands to the steering motor, and also to send steering commands back to the actuators  2  to ensure a complete feedback loop. This provides full fidelity between the desired steering and driving action and the desired wheel toe angle of all wheels  50  that will achieve and enhance the desired action. 
     Two-way communication of data from the present actuator&#39;s  2  integral force sensors  20  and Hall sensor  54  is also possible between any number of secondary vehicle systems including, but not limited to anti-lock braking systems (ABS), the engine, air bags and other safety systems, parking assist systems, vehicle transmission and navigation systems. This two-way communication not only informs such systems on steering and toe angle, but also provides the present actuators  2  with information on any number of the vehicles other systems, alerting the actuator to abnormal behavior or failures of other systems. For example, brake or engine failure data or deployment of air bags can be sent to the actuators  2  which in turn will adjust wheel toe angles to assist in stopping the vehicle. Alternatively navigation and route programming data can be sent to the steering module  62  and the actuator  2  to self-steer a vehicle to a desired destination. 
     In steer-by-wire operation, the present actuator system can preferably be used as a backup system if the steer-by-wire system were to fail. In such case, the present actuators  2  with their internal force sensor  20  and Hall sensors  54  can take over steering operation and adjustment at limited speeds and in safe or emergency vehicle operation mode. 
     The present actuators  2  can further preferably be used in conjunction with a vehicle&#39;s navigation system, in which case a global positioning system (GPS) and mapping systems can be used to take a vehicle for a starting point to a programmed destination with none to little manual steering needed. 
     The present actuators  2  can also be useful in parking assist systems available in many vehicles. In this application, the present actuator system is able to turn wheels at certain desired toe angles to achieve parking in smaller parking spots. 
     The present actuators  2  can also be used to adjust wheel camber or caster, as illustrated in  FIG. 10 . In such cases one or more actuators  2  can be affixed to a control arm  66  that is connected at one end to an upper or lower portion the wheel  50  and at another end to the vehicle body  58  or sub frame. While  FIG. 10  illustrates the actuator in relation to an upper portion of the wheel  50  it would be well understood by a person skill in the art that other connection locations on the wheel  50  are also possible and will achieve the result of camber adjustment and control when used with the present actuator  2 . In this arrangement, actuation of the actuator  2  serves to draw in or draw out the control arm  66 , moving in or out an upper or lower portion of the wheel, to thereby adjust camber or caster. As described previously, integral force sensors  20  and Hall sensors  54  provide real-time and constant feedback to both the rotation assembly  12  and to the active suspension control  52  to adjust rotation and thereby adjust and control the control arm  66  length. 
     With reference to  FIG. 10 , the upper wheel of this figure illustrates a camber position preferable for straight driving to achieve minimum friction and therefore also minimal fuel consumption. The lower wheel of  FIG. 10  illustrates a camber and caster position preferable for turning or braking, where more friction may be needed to provide control. 
     With reference to  FIG. 11 , the present actuators  2  can also be used to adjust vehicle height. In such cases one or more actuators  2  can be affixed directly to a strut  64  that is linked via control arm  66  to an upper or lower portion the wheel  50  and connected to the vehicle suspension  56  or to the vehicle body  58 . While  FIG. 11  illustrates the actuator in relation to an upper portion of the wheel  50  it would be well understood by a person skill in the art that other connection locations on the wheel  50  are also possible and will achieve the result of vehicle height adjustment and control when used with the present actuator  2 . In this arrangement, actuation of the actuator  2  serves to extend or contract the strut  64 , which in turn raises or lowers the control arm  66 , to thereby adjust the vehicle height. As described previously, integral force sensors  20  and Hall sensors  54  provide real-time and constant feedback to both the rotation assembly  12  and to the active suspension control  52  to adjust rotation and thereby adjust and control the control arm  66  position. 
     If any of the vehicle&#39;s wheels  50  are spinning or not making contact with the ground, the present actuators  2  can be actuated to extend those particular wheels  50  to make contact with ground or to retract other wheels to balance wheel contact of all vehicle wheels. The present actuators  2  can send wheel height data to the active suspension control  52  and to adjust car load, steering, ABS, and possibly also to engine transmission. 
     The present actuator system can further preferably be used for to balance a vehicle&#39;s weight distribution and brake force distribution in cases where the vehicle&#39;s dynamic stability control (DSC) and/or ABS is activated. In such cases, adjusting vehicle height on a chosen wheel serves to change the load on that wheel. This wheel load data can then be sent to the DSC system and can be used to adjust anti-lock braking, traction control and in some vehicles switch driving mode from two-wheel drive to all-wheel drive if needed. 
     Since more than one actuator  2  can be affixed to a particular wheel  50 , vehicle height, toe angle, caster and camber may all be adjusted for a particular wheel  50  simply by installing the present actuators  2  on the wheel linkages of choice. As well vehicle height, camber, caster and toe angle may be adjusted and controlled as part of a conventional feedback system as illustrated in  FIG. 8 , or by a steer-by-wire system as illustrated in  FIG. 9 . 
     In the foregoing specification, the invention has been described with specific embodiments thereof; however, it will be evident that various modifications and changes may be made thereto without departing from the broader scope of the invention, which is limited only by the claims.