Abstract:
A method for changing the track of a vehicle ( 100 ) having first and second wheels ( 108, 110 ) disposed on opposing sides of the vehicle ( 100 ) along a line generally perpendicular to the direction of travel of the vehicle, the first and second wheels ( 108, 110  are supported on first and second wheel supports ( 114, 116, 204 ) to permit the track of the first and second wheels ( 108, 110 ) to be adjusted, at least one actuator ( 218, 220 ) is coupled to at least one wheel of the first and second wheels ( 108, 110 ) and is configured to change the toe angle of said first and second wheels ( 108, 110 ), and an electronic control unit ( 402 ) is coupled to the actuator ( 218, 220 ) that is configured to command the actuator ( 218, 220 ) to change the toe angle, the method comprising the steps of changing the toe angle of the first and second wheels ( 108, 110 ); rolling the vehicle ( 100 ) on the first and second wheels ( 108, 110 ) over the ground to generate opposing lateral forces on the first and second wheels ( 108, 110 ); and applying the opposing lateral forces to the first and second wheel supports ( 114, 116, 204 ) to change the track of the first and second wheels ( 108, 110 ).

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to motor vehicles. More particularly it related to motor vehicles having adjustable track. Even more particularly it is related to motor vehicles with an adjustable track that are configured to change toe angle to assist in changing the track. 
       BACKGROUND OF THE INVENTION 
       [0002]    Automatically adjustable toe angle systems for automobiles have been in existence for many years. International class B62D17 is directed to automatic camber, caster, and toe-in adjustment systems. 
         [0003]    WO2010045999 shows automatic adjustment devices for the toe angle of an automobile by sensing driving-critical conditions. 
         [0004]    EP2163412 teaches algorithms for a toe angle adjustment ECU of an automobile. 
         [0005]    DE 102008027326 teaches a single actuator adjustment system for simultaneously changing the toe angle of automobile wheels. 
         [0006]    WO2009113642 teaches a toe angle adjustment controller for dynamically adjusting the toe angle of an automobile&#39;s rear wheels. 
         [0007]    EP2067689 teaches a toe angle adjustment system for dynamically adjusting the rear wheel toe angle based on a steering angle velocity. 
         [0008]    None of the above systems have been provided on vehicles that have an adjustable track. 
         [0009]    None of the above systems are used to solve the problem of changing the vehicle track with a reduced force. 
       SUMMARY OF THE INVENTION 
       [0010]    The technical problem solved by the present invention is that of changing the toe angle of a vehicle to assist in changing the track of a vehicle by reducing or eliminating the force required to change the track of a vehicle. 
         [0011]    The solution, as provided herein, includes a method of automatically changing the toe angle of the wheels and then moving the vehicle over the ground with this changed toe angle in order to increase or decrease the track of the vehicle. 
         [0012]    The operator may manually select the toe angle he desires and the system may be configured to responsively and automatically change the toe angle. The operator can then drive the vehicle forward or backward until the inward or outward for generated by the toe-in or toe-out pushes together or pulls apart the wheels to thereby decrease or increase the track, respectively. 
         [0013]    The operator may manually select a desired track and the system may automatically and responsively change the toe angle as the operator drives the vehicle over the ground until the appropriate track is reached. The system may automatically change the toe angle once the vehicle has achieved the selected track to prevent further changes in track. 
         [0014]    The terms “front”, “in front of”, “forward”, “behind”, “rear”, “to the rear of” and the like refer to the direction the vehicle travels during normal field operations. 
         [0015]    “Track” as the term is used herein refers to the spacing between a rear wheel on the left side of the vehicle and a rear wheel on the right side of the vehicle. 
         [0016]    As used herein, wheels are “toe-out” when planes passing through the wheels and normal to the rotational axes of the wheels intersect each other at ground level at a point forward of both wheel hubs. 
         [0017]    As used herein, wheels are toe-in when planes passing through the wheels and normal to the rotational axes of the wheels intersect each other at ground level at a point to the rear of both wheel hubs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a plan view of a vehicle in accordance with the current invention. 
           [0019]      FIG. 2  is a rear view of the rear axle arrangement of the vehicle before the toe angle is changed and the track increased. 
           [0020]      FIG. 3  is a rear view of the rear axle arrangement of the vehicle after the toe angle has been changed and the track increased. 
           [0021]      FIG. 4  is a schematic diagram of the automatic toe angle adjustment system. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    In a vehicle with adjustable track, an automatic toe adjustment system is provided to reduce or eliminate the effort required to increase or decrease the track of the vehicle. 
         [0023]    Referring to  FIG. 1 , the vehicle  100 , here shown as a combine harvester, consists of a chassis  102  supported on two front wheels including left front wheel  104  and right front wheel  106 , and two rear wheels including left rear wheel  108  and right rear wheel  110 . 
         [0024]    All four wheels are driven and steered by motors (not shown) under the control of an operator who operates the vehicle from an operator&#39;s cab  112 . 
         [0025]    The vehicle  100  has extendible rear axles including a left rear extendible axle  114  and a right rear extendible axle  116 . 
         [0026]    Left rear extendible axle  114  is coupled to and supports left rear wheel  108  for rotation. When it is extending, left rear extendible axle  114  moves left rear wheel  108  outward and away from the side of the vehicle and moves the wheel inwardly when retracting. 
         [0027]    Right rear extendible axle  116  is coupled to and supports right rear wheel  110  for rotation. 
         [0028]    When it is extending, right rear extendible axle  116  moves right rear wheel  110  outward and away from the side of the vehicle, and moves the wheel inwardly when retracting. 
         [0029]    Referring to  FIG. 2 , extendible axles  114 ,  116  are supported on and slidably received in opposing ends  200 ,  202  of a central axle portion  204  that is coupled to the chassis  102  at a central pivot point  205  to pivot with respect to chassis  102  about a pivoting axis that extends generally horizontally and longitudinally parallel to the direction of travel of the vehicle over the ground in a straight line. This pivoting axle arrangement is typically of combine harvesters and is provided to permit the vehicle load to be continuously equalized on the left and right rear wheels as the vehicle moves through the field. 
         [0030]    The extendible axles  114 ,  116  are coupled to actuators  206 ,  208 , here shown as hydraulic cylinders, which are disposed to extend and retract the extendible axles  114 ,  116  with respect to the sides of the vehicle. 
         [0031]    Left and right rear wheel angle position sensors  210 ,  212  are disposed to sense the steering angle of the left and right rear wheels, respectively. They provide signals indicative of the wheel angle positions of the rear wheels. The sensors indicate the angular position to which each wheel is steered. The toe angle is the difference between the steering angle of the left rear wheel and the steering angle of the right rear wheel. Thus the steering angles of the left rear wheel and the right rear wheel indicate the toe angle. 
         [0032]    Two axle extension sensors  214 ,  216  are disposed to sense the degree of extension of extendable rear axles  114 ,  116 , respectively. They provide signals indicative of the degree of extension of the extendable rear axles. 
         [0033]    Left and right steering actuators  218 ,  220  are fixed to the outer ends of extendable rear axles  114 ,  116 , respectively, and are configured to steer the left and right rear wheels  108 ,  110  both to the left and to the right with respect to a straightahead position. 
         [0034]    It is desirable to extend or retract the rear wheels. Extending and retracting the rear wheels changes the track of the rear wheels. In one instance, it may be desirable to extend the wheels to a first track spacing to harvest a first row crop with a first row spacing, and then change the track to harvest a second row crop in a second field with a second and different row spacing. 
         [0035]    Actuators  206 ,  208  may be extended and retracted gradually as the vehicle moves through the field in order to extend and retract extendable rear axles  114 ,  116 , respectively. On occasion, however, it may be desirable to rapidly change the track of the rear wheels. If, for example, the operator attempts to use actuators  206 ,  208  to extend the extendable rear axles when the vehicle is stationary and the rear wheels have sunk in the earth, actuators  206 ,  208  may be unable to extend the extendable rear axles without damaging some portion of the vehicle. 
         [0036]      FIG. 3  illustrates the arrangement of the rear axle when the extendable axles  114 ,  116  have been extended. They are shown telescoped outward from the central axle portion  204  which is tubular and in which the extendable axles  114 ,  116  are slidably and telescopically supported. 
         [0037]    To make this extension process easier and reduce the forces applied to the rear axle, the system is configured to change the toe angle of the rear wheel to a more toe-in or more toe-out angle during the axle extension process, depending upon whether the track is being decreased or increased, respectively. 
         [0038]    In one mode of operation, the system is configured to increase the track by signaling actuators  218 ,  220  to move the rear wheels to a toe-out position. In a toe-out position, when the vehicle moves forward, the left rear wheel  108  pulls left rear extendable axle  114  outward to the left and the right rear wheel  110  pulls right rear extendable axle  116  outward to the right, in the opposite direction, thus tending to increase the distance between the 2 wheels. 
         [0039]    At the same time, the system is configured to signal actuators  206 ,  208  to extend and to apply force to extendable rear axles  114 ,  116 , thereby assisting in sliding extendable rear axles  114 ,  116  outward from central axle portion  204 . 
         [0040]    In an alternative arrangement, clamps may be provided in place of actuators  206 ,  208 , and the system may automatically release these clamps to permit extendable rear axles  114 ,  116  to extend outward as the wheels in their toe-out position extend the rear axles as the vehicle rolls forward over the ground. 
         [0041]    In another mode of operation, the system is configured to decrease the track by signaling actuators  218 ,  220  to move the rear wheels to a toe-in position. In a toe-in position, when the vehicle moves forward, the left rear wheel  108  pulls left rear extendable axle  114  inward to the right and the right rear wheel  110  pulls right rear extendable axle  116  inward to the left, in the opposite direction, thus tending to decrease the distance between the 2 wheels. 
         [0042]    At the same time, the system is configured to signal actuators  206 ,  208  to retract, thereby assisting in sliding extendable rear axles  114 ,  116  inward into central axle portion  204 . 
         [0043]    In an alternative arrangement, clamps may be provided in place of actuators  206 ,  208 , and the system may automatically release these clamps to permit extendable rear axles  114 ,  116  to extend outward as the wheels in their toe-out position extend the rear axles as the vehicle rolls forward over the ground. 
         [0044]    In a third mode of operation, the system is configured to extend the extendable rear axles in the same manner described above, but by moving the wheels to a toe-in position, and rolling the vehicle over the ground in reverse. 
         [0045]    In a fourth mode of operation, the system is configured to retract the extendable rear axles in the same manner described above, but by moving the wheels to a toe-out position, and rolling the vehicle over the ground in reverse. 
         [0046]    In one variation of the above modes of operation, the system is configured to change the track by first extending (or retracting) one axle and then by extending (or retracting) the other axle. This reduces the power demands on the engine by only requiring one actuator  206 ,  208  to be operated at a time. 
         [0047]    In another variation of the above modes of operation, the system is configured to change the track by simultaneously extending and retracting both axles. This requires more power, but it permits the track change to occur faster. 
         [0048]    In another variation of the above modes of operation, the system is configured to begin the track change process at the operator&#39;s command and to cease the track change process by the operator&#39;s command using an operator input device. 
         [0049]    In another variation of the above modes of operation, the system is configured to begin the track change process at the operator&#39;s command and to end the track change process automatically when a particular track has been achieved. 
         [0050]    In this variation, the operator selects a desired track with an operator input device. The system responsively increases (or alternatively decreases) the toe angle. As the vehicle is driven over the ground, the track is increased (or alternatively decreased). The system is configured to repeatedly monitor the axle extension sensors  214 ,  216  and to compare the sensed axle extension with the operator&#39;s selected track as the track is increased (or alternatively decreased). Once the system determines that the track is equal to the operator&#39;s selected track in this comparison, the system automatically, and with no additional input from the operator, changes the toe angle to reduce or eliminate the ground forces applied to the wheels that work to increase (or alternatively decrease) the track. 
         [0051]    The process of changing the track in any of the above modes of operation can be done passively using solely the force generated by a toe in or toe out orientation of the rear wheels and rolling the vehicle over the ground. 
         [0052]    Alternatively the process of changing the track in any of the modes of operation can be actively by the combined effort of (1) rolling the vehicle (while having a non-zero toe angle, either toe in or toe out) and (2) driving the actuators  206 ,  208  to assist this operation by track change process can be assisted by and to process by extending (or retracting) the extendable rear axles  114 ,  116  at the operator&#39;s command. 
         [0053]    The system is also configured to calculate an appropriate degree of axle extension of each of the extendable rear axles  114 ,  116 , and to cease extending the axles when it determines that the appropriate degree of extension has been reached. The system is configured to cease extending the axles by (1) locking actuators  206 ,  208 , and/or by (2) locking the clamps discussed above and/or by steering rear wheels  108 ,  110  to a straightahead (or more straightahead) position using actuators  218 ,  220 . 
         [0054]    The system is configured to determine that the appropriate degree of extension of each of the rear extendable axles  114 ,  116  has have been reached by monitoring sensors  214 ,  216 , respectively. 
         [0055]      FIG. 4  shows a schematic diagram of automatic adjustable toe angle system  400 . An electronic control unit (ECU)  402  is coupled to left and right wheel angle position sensors  210 ,  212 ; left and right rear axle extension sensors  214 ,  216 ; valve driver circuit  404 ; and operator input device  406 . Valve driver circuit  404 , is coupled to electronic control valves  408 ,  410 ,  412 , and  414 , that are interned coupled to end selectively drive left actuator  206 , right actuator  208 , left steering actuator  218 , and right steering actuator  220 . Each of the electronic control the House  408 ,  410 ,  412 , and  414  is respectively coupled to a source of hydraulic fluid under pressure  416  and a low-pressure hydraulic fluid return reservoir  418 . 
         [0056]    ECU  402  is a digital microprocessor based electronic control unit including a digital memory  420  which comprise a plurality of digital machine-readable instructions. These instructions configure ECU  402 , and hence configure the system  400  to operate in all the modes of operation and their alternatives that are described herein. 
         [0057]    ECU  402  is configured by its instructions to read the signals provided by sensors  210 ,  212 ,  214 ,  216 , and operator input device  406 . Operator input device  406  is manually operable by the operator to permit the operator to select any of the modes of operation, alternative modes of operation, and commands or selections described herein. Operator input device  406  may comprise any arrangement of joysticks, knobs, quadrant levers, handles, switches, displays, touch screens, touch pads, digitizer, voice-recognition system or other device configured to transmit signals to ECU  402  for further processing as a digital value. 
         [0058]    ECU  402  is further configured by its instructions to perform the calculations described above, and to responsively signal valve driver circuit  404  to drive valves  408 ,  410 ,  412 ,  414  to change the toe angle and track. 
         [0059]    The invention is not limited to the particular embodiment illustrated herein, but includes any embodiment that falls within the scope of the appended claims. 
         [0060]    For example, ECU  402  is schematically illustrated in  FIG. 4  as a single item. ECU  402  can include multiple digital microprocessors. They can be disposed apart from each other. They can be connected over a digital computer network. They may share the computational requirements to perform the functions described herein. In a preferred arrangement, ECU  402  comprises a plurality of digital microprocessor-based electronic control units that are coupled together over a communications bus, preferably a serial communications bus, more preferably a CAN bus, and even more preferably a CAN bus in accordance with the J1939 standard. 
         [0061]    As a further example, the rear wheels are shown supported on an extendable axle that is extended by hydraulic cylinders to change the track. In another arrangement, the rear wheels may be supported on an arm that is coupled to the chassis to pivot toward or away from the chassis and thereby change the track. In another arrangement, each rear wheel may be supported on a multiple bar mechanical linkage coupled to the chassis to permit the rear wheels to move toward or away from the chassis and thereby change the track. 
         [0062]    As yet another example, while hydraulic actuators are disclosed herein, the actuators may be electrical, electrohydraulic, or pneumatic actuators. 
         [0063]    Linear actuators are illustrated herein to extend and retract the rear extendable axles. These actuators may be rotary actuators. 
         [0064]    A single actuator is disclosed herein for extending each axle, and a single actuator is disclosed herein for steering each wheel. In an alternative arrangement, a plurality of actuators may function together to both extend the axles and to steer the wheels. 
         [0065]    U.S. patent application Ser. No. 12/463,628, which was filed May 11, 2009 shows extendable axle, actuator and sensor arrangements that can all be substituted for the arrangement disclosed herein. The &#39;628 application is incorporated herein by reference for all that it teaches. All of the embodiments of the &#39;628 application are configured as described herein to extend the axles by changing the toe angle, and therefore all of the embodiments of the &#39;628 application, configured as described herein, fall within the scope of the present claims.