Patent Publication Number: US-6659080-B2

Title: Methods and apparatus for adjusting a throttle of a vehicle engine

Description:
TECHNICAL FIELD 
     The present invention generally relates to vehicle controls and, more particularly, to methods and apparatus for adjusting a throttle of a vehicle engine. 
     BACKGROUND OF THE INVENTION 
     Operation of a vehicle generally includes operator adjustment of a throttle to select the operating level of the vehicle engine. For example, operation of an automobile generally includes adjusting the fuel injectors, engine spark and amount of airflow through an intake manifold to an intake port of an internal combustion engine in response to operator adjustment of the throttle. The operator adjustment of the throttle is typically accomplished with an input mechanism, such as a foot pedal, joystick, hand pedal, lever or track ball, which is coupled to an input sensor. The input sensor provides an input signal to a processor that generates the control signals for the hardware of the vehicle engine to provide the operating level indicated by the input mechanism. 
     The ability of the operator to accurately adjust the input mechanism for a maximum operating level of the vehicle engine can be limited by a number of factors. For example, the physical characteristics of an operator (e.g., height) can limit the ability of the operator to position the input mechanism at a location that provides the maximum operating level of the vehicle engine. In addition, variations in the placement of the input mechanism within a vehicle compartment or variations in obstructions to the motion of the input mechanism (e.g., floor mat thickness) can limit the ability of an operator to obtain the maximum operating level. Therefore, these and other factors that limit the ability of the operator to adjust the input mechanism for a maximum operating level of the vehicle engine can result in undesirable attributes of the throttle, such as a dead pedal at maximum pedal travel. 
     In view of the foregoing, it should be appreciated that it would be desirable to provide methods and apparatus for adjusting a throttle of a vehicle engine to address these and other variations that limit the ability of an operator to accurately obtain the maximum operating level of the vehicle engine. Furthermore, additional desirable features will become apparent to one skilled in the art from the foregoing background of the invention and following detailed description of a preferred exemplary embodiment and appended claims. 
     SUMMARY OF THE INVENTION 
     In accordance with the teachings of the present invention, methods and apparatus are provided for adjusting a throttle of a vehicle engine to obtain the maximum operating level of the vehicle engine. The apparatus comprises an input sensor configured to provide an input signal having a value that corresponds to an operating level of the vehicle engine requested by an operator and a memory configured to store a maximum input value for the input sensor. The maximum input value provides the value of the input signal that corresponds to a maximum operating level of the vehicle engine. The apparatus is further configured to receive the input signal and access the memory to retrieve the maximum input value and further configured to update the maximum input value with the value of the input signal if the value of the input signal is greater than the maximum input value. The processor is also configured to generate a throttle control signal that controls the throttle of the vehicle engine using the maximum input value and the input signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements, and: 
     FIG. 1 is a simplified diagram of an apparatus for adjusting a throttle of a vehicle engine according to a preferred exemplary embodiment of the present invention; and 
     FIG. 2 is a flow chart illustrating a method for adjusting a throttle of a vehicle engine according to a preferred exemplary embodiment of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS 
     The following detailed description of preferred exemplary embodiments of the invention is mainly exemplary in nature and is not intended to limit the invention or the application or use of the invention. 
     Referring to FIG. 2, an apparatus  20  is illustrated for adjusting a throttle  22  of a vehicle engine  24  according to a preferred exemplary embodiment of the present invention. The apparatus  20  is comprised of an input sensor  26  that is configured to provide an input signal  28  having a value that approximately corresponds to an operating level of the vehicle engine  24  requested by an operator (not shown). The apparatus  20  is also comprised of a memory  30  that is configured to store a maximum input value (e.g., MAX_INPUT_ 1 )  32  for the input sensor  26  and a processor  34  configured to receive the input signal  28  provided by the input sensor  26 . The processor  30  is also configured to access the memory  30  to retrieve the maximum input value  32 . The processor  34  is further configured to compare the value of the input signal  28  and the maximum input value  32  and update the maximum input value  32  with the value of the input signal  28  if the value of the input signal  28  is greater than the maximum input value  32 . 
     In addition to comparing the value of the input signal  28  and the maximum input value  32  and updating the maximum input value  32  with the value of the input signal if the value of the input signal  28  is greater than the maximum input value  32 , the processor  34  is configured to generate a throttle control signal  36  that controls the throttle  22  of the vehicle engine  24  using the maximum input value  32  and the input signal  28 . The processor  34  can be configured to generate the throttle control signal  36  that reflects the operating level of the vehicle engine  24  requested by the operator using any number of methods. For example, and without any intention to limit the invention to this method of generating the throttle control signal  36 , the processor  34  can be configured to determine a ratio of the maximum input value  32  to the input signal  28  [e.g., (value of the input signal  28 )/(maximum input value  32 )] and generate the throttle control  36  that provides the fraction of the maximum operating level for the vehicle engine of the determined ratio [e.g., {fraction (5/10)}=a throttle control signal  36  that configures the throttle for fifty percent (50%) of the maximum operating level of the vehicle engine]. However, as previously described in this detailed description of preferred embodiments, any number of methods can be utilized to generate the throttle control signal  36  using the maximum input value  32 . Furthermore, any number of throttle configurations and any number of vehicle engines for any number of land (e.g., automobiles, trains), air (e.g., aircraft), water (e.g., ships) and space vehicles can be utilized in accordance with the present invention. 
     For example, and for illustrative purposes only, the throttle  22  can include an electronically-controlled intake valve  38 , such as a butterfly or rotary intake air valve, disposed within an intake bore  40 , which rotates to adjust a flow rate of air through the intake bore  40  to the vehicle engine  24 , which is an internal combustion engine in this illustrative example. An electromechanical actuator  42 , such as a Direct Current (DC) motor or step motor, is mechanically linked to the electronically-controlled intake valve  38  with a rotatable output shaft (not shown). The rotational position of the output shaft and the corresponding flow rate of air to the vehicle engine  24  are controlled through the variation of the throttle control signal  36  issued by the processor  30 . 
     As previously described in this detailed description of preferred exemplary embodiments, the processor  34  is configured to generate the throttle control signal  36  that controls the throttle  22  of the vehicle engine  24  using the maximum input value  32  and the input signal  28 . The input sensor  26  preferably produces the input signal  28  as the operator alters the position of the input mechanism  44 , such as an accelerator pedal. However, any number of input mechanisms can be used in accordance with the present invention, such as a foot pedal, hand pedal, joystick, lever or trackball. The operator to request an operating level of the vehicle engine  24  uses the input mechanism  44 . The position of the input mechanism  44  is detected by the input sensor  26 , which can be any number of sensors such as a potentiometric position sensor, and converted to the input signal  24  using any number of techniques, such as a transduction. As can be appreciated by one of ordinary skill in the art, the apparatus  20  for adjusting the throttle of the vehicle engine  22  as previously described in this detailed description of preferred embodiments provides numerous benefits, and a method  46  for adjusting a throttle of a vehicle engine is illustrated in FIG. 2 according to a preferred exemplary embodiment of the present invention, which can be utilized with the apparatus  20  of FIG.  1 . 
     Referring to FIG. 1, the method  46  is comprised of receiving the input signal having a value that corresponds to an operating level of the vehicle engine requested by the operator of the vehicle  48  and comparing the input signal to a maximum input value that provides a value of the input signal that approximately corresponds to a maximum operating level of the vehicle engine  50 . The method  46  is further comprised of updating the maximum input value with the value of the input signal if the value of the input signal is greater than the maximum input value  52 . In addition, the method  46  is also comprised of generating a throttle control signal that is configured to control the vehicle engine using the maximum input value and input signal  54 . Furthermore, the method  46  can also optionally include determining whether an error condition exists  56 , filtering the input signal  58 , and determining whether the maximum input value is a valid value  60  in accordance with the present invention. 
     More specifically, the method  46  can be configured to determine whether any number of error conditions exist  56  that directly or indirectly relate to the throttle function of the vehicle engine. For example, an evaluation of the input signal can be conducted to determine if the accelerator position signal is out of a predetermined range or determine whether an electrical short is present. If a determination is made that an error condition exists, the method  64  continues with generating the throttle control signal that is configured to control the throttle of the vehicle engine using the maximum input value and the input signal  54  without comparing the input signal to a maximum input value that provides a value of the input signal, which corresponds to the maximum operating level of the vehicle engine  50  and subsequent steps. Otherwise, the method  46  preferably continues with comparing the input signal to the maximum input value that provides a value of the input signal, which corresponds to a maximum operating level of the vehicle engine  50  after the filtering of the input signal  58 . 
     The input signal  54  can be filtered with any number of filters such as a first order lag filter. The filtering of the input signal  58  and determining whether an error condition exists  56  prior to comparing the throttle position to the maximum input value  50  increase the fault tolerance of the method  46 , and the fault tolerance of the method  46  can also be increased with determining whether the maximum input value is a valid value  60  after updating the maximum input value with the value of the input signal if the value of the input signal is greater than the maximum input value  52 . 
     The determining whether the maximum input value is a valid value  60  can include any number of validation conditions. For example and without any intention to limit the validation conditions, the validation conditions can include a predefined minimum value and a predefined maximum value that define a valid range for the maximum input value, which is considered to be invalid if the value is outside the range (i.e., the maximum input value is greater than and/or equal to the predefined maximum value or less than and/or equal to the predefined minimum value). If the determination is made that the maximum input value is not valid, the maximum input value is preferably set to a predefined value  64  prior to generating the throttle control signal that is configured to control the throttle of the vehicle engine using the maximum input value and input signal  54 . In addition to determining whether the maximum input value is a valid value  60 , determining whether an error condition exists  56  and/or filtering the input signal  58 , fault tolerance can also be increased with verification of the memory  30  of FIG.  1 . 
     For example and with reference to FIG. 1, the memory  30  that is configured to store the maximum input value  32  is preferably a Keep-Alive-Memory (KAM). This provides for a retention of the adjusted maximum input value  32  from key-cycle to key-cycle of the vehicle. However, in order to ensure that an appropriate value for the maximum input value  32  is retained from key-cycle to key-cycle, a memory corruption test is preferably conducted on the memory  30  and the maximum input value  32  is reset to a predefined value if the memory fails the memory corruption test. In addition, the apparatus  20  can be configured to reduce the maximum input value  32 . 
     More specifically and according to another embodiment of the present invention, the processor  34  can be configured to access the memory  30 , retrieve the maximum input value  32 , and decrement the maximum input value  32  by a predetermined amount at least once per key-cycle. The processor  30  can also be provided with a minimum value, below which the processor  30  cannot reduce the maximum input value  32 , and a maximum value, above which the processor  30  cannot increase the maximum input value  32 . As can be appreciated by one of ordinary skill in the art, this provides for adjustment of the throttle if the limitations to the ability of the operation to position the input mechanism at a location that provides the maximum operating level of the vehicle engine is removed or reduced or an operator with different limitations is operating the vehicle. 
     Continuing with reference to FIG. 2, hardware redundancy is preferably provided in another preferred embodiment of the present invention to increase fault tolerance. The hardware redundancy can be provided with a second input sensor  66  that is configured to provide a second input signal  68  having a second value that approximately corresponds to the operating level of the vehicle engine  24  requested by an operator (not shown). The memory  30  is also configured to store a second maximum input value (e.g., MAX_INPUT_ 2 )  70  for the second input sensor  66 , and the processor  34  is configured to receive the second input signal  68  provided by the input sensor  66  and access the memory  30  to retrieve the second maximum input value  70 . The processor  34  is further configured to compare the value of the input signal  28  and the maximum input value  32  and compare the value of the second input signal  68  and the second maximum input value  70  and update the maximum input value  32  with the value of the input signal  28  and update the second maximum input value  70  with the value of the second input signal  68  if the value of the input signal  28  is greater than the maximum input value  32  and the value of the second input signal  68  is greater than the second maximum input value  70 . 
     In addition to comparing the values of the input signals ( 28 , 68 ) and the maximum input values ( 32 , 70 ) and updating the maximum input values ( 32 , 70 ) with the values of the input signals ( 28 , 68 ) if the values of the input signals ( 28 , 68 ) are greater than the maximum input values ( 32 , 70 ), the processor  34  is configured to generate the throttle control signal  36  that controls the throttle  22  of the vehicle engine  24  using the first maximum input value  32  and the second maximum throttle value  70 . The processor  34  can be configured to generate the throttle control signal  36  that reflects the operating level of the vehicle engine  24  requested by the operator as previously described in this detailed description of preferred embodiments with fault tolerance. The fault tolerance can be provided with a greater number of input sensors than the input sensor  26  and the second input sensor  66 , a greater number of input signals than the input signal  28  and the second input signal  68 , and a greater number of maximum input values than the maximum input value  32  and the second maximum input value  70 . In addition, as can be appreciated by one of ordinary skill in the art, the method  46  for adjusting a throttle of a vehicle engine of FIG. 2 can be modified to include steps that incorporate the redundant hardware as previously described for the preceding embodiment of the present invention. 
     From the foregoing detailed description of preferred exemplary embodiments, it should be appreciated that apparatus and methods are provided for adjusting a throttle of a vehicle engine to address variations that limit the ability of an operator to accurately obtain the maximum operating level of the vehicle engine. While preferred exemplary embodiments have been presented in the foregoing detailed description of preferred exemplary embodiments, it should be appreciated that a vast number of variations exist. It should also be appreciated that these preferred exemplary embodiments are only examples and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the ensuing detailed description will provide those skilled in the art with a convenient road map for implementing a preferred embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary preferred embodiment without departing from the spirit and scope of the invention as set forth in the appended claims.