Abstract:
In a vehicle having a manual transmission, various sensors such as pedal and gearshift position sensors and accelerometers provide data to a control module such as an engine control module. The control module includes a microprocessor which calculates derivatives, i.e., the rate of change (first derivative) or the rate of change of the rate of change (second derivative) of the data from the sensors. Based on these derivatives, the microprocessor classifies the current driving activity into one of two, three or more modes, for example, track, sport and touring. During a shift, from the data from the gearshift sensor, the microprocessor determines whether an upshift or downshift is imminent or in progress and decreases or increases the engine speed to achieve zero or negligible cross clutch speed differential upon clutch engagement, rapidly if in the first (track) mode, less rapidly in the second (sport) mode and less rapidly still in the third (touring) mode.

Description:
FIELD 
       [0001]    The present disclosure relates to manual transmission control systems and more particularly to a manual transmission control system and method which adjust a rate of clutch engagement to the current style of driving of the vehicle operator. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    Manual motor vehicle transmissions have always been prized by driving enthusiasts for both their objective performance and their contribution to the subjective experience of driving. This is not to say, however, that certain aspects of manual transmissions cannot be improved by the application of modern computer and microprocessor technology. 
         [0004]    A particularly beneficial application of technology involves shaft speed and clutch control and the concept of matching the clutch input speed, that is, the engine output speed, to the transmission input speed when the clutch is about to be closed to engage a new selected gear. Such speed or rev matching improves shift quality and greatly enhances the service life of the clutch. 
         [0005]    Unfortunately, it is often necessary to substantially and rapidly increase or decrease the engine speed prior to clutch closure to achieve such zero cross clutch speed differential. When the vehicle is being driven in a aggressive, sporty manner such a rapid speed change may both be necessary and unnoticed but when this same speed change, especially a commanded rapid speed increase, occurs during casual driving it can be both disconcerting and annoying to the driver. 
         [0006]    Accordingly, an engine control system that matches the rate of engine speed increase or decrease prior to clutch closure to the current style of driving, that is, competitive, aggressive, conventional or casual, for example, to achieve zero cross clutch speed differential would be desirable. The present invention is so directed. 
       SUMMARY 
       [0007]    The present invention provides a variable speed or rev matching control system and method that matches the rate of engine speed increase or decrease to the current style of driving to achieve zero or negligible cross clutch speed differential at the moment of clutch engagement. As used throughout this document, it should be understood that the term “rev matching” is a shortened or abbreviated term meaning matching revolutions per minute of two rotating components, in this case, the output shaft speed of an engine with the input shaft speed of a manual transmission. In a vehicle having a manual transmission, various sensors such as pedal and gearshift position sensors and accelerometers provide data to a control module such as an engine control module. The control module includes a microprocessor which calculates derivatives, i.e., the rate of change (first derivative) or the rate of change of the rate of change (second derivative) or higher derivatives of the data from certain sensors. Based on these derivatives, the microprocessor classifies the current driving activity into one of two, three or more modes, for example, track, sport and touring. During a shift, from the data from the gearshift sensor, the microprocessor determines whether an upshift or downshift is imminent or in progress and decreases or increases the engine speed to achieve zero or negligible cross clutch speed differential upon clutch engagement, rapidly if in the first (track) mode, less rapidly in the second (sport) mode and less rapidly still in the third (touring) mode. 
         [0008]    Thus it is an aspect of the present invention to provide a variable rev or speed matching control system that matches the rate of engine speed increase or decrease to the current style of driving to achieve zero or negligible cross clutch speed differential at the moment of clutch engagement. 
         [0009]    It is a further aspect of the present invention to provide a variable rev or speed matching control method that matches the rate of engine speed increase or decrease to the current style of driving to achieve zero or negligible cross clutch speed differential at the moment of clutch engagement. 
         [0010]    It is a still further aspect of the present invention to provide a variable rev matching control system that includes various sensors such as pedal and gearshift position sensors and accelerometers to provide data to a control module. 
         [0011]    It is a still further aspect of the present invention to provide a variable rev matching control system that includes various sensors such as pedal and gearshift position sensors and accelerometers to provide data to a control module such as an engine control module (ECM) having a microprocessor. 
         [0012]    It is a still further aspect of the present invention to provide a variable rev matching control system that includes a microprocessor which calculates a derivative, i.e., the rate of change (first derivative) or the rate of change of the rate of change (second derivative) or higher derivatives of the data from certain sensors. 
         [0013]    It is a still further aspect of the present invention to provide a variable rev matching control system that includes a microprocessor that classifies the current driving activity into one of two, three or more modes, for example, track, sport and touring. 
         [0014]    It is a still further aspect of the present invention to provide a variable rev matching control system that includes a microprocessor that determines whether an upshift or downshift is imminent or in progress and decreases or increases the engine speed to achieve zero cross clutch speed differential upon clutch engagement, rapidly if in a first (track) mode, less rapidly in a second (sport) mode and less rapidly still in a third (touring) mode. 
         [0015]    Further advantages, aspects and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0016]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0017]      FIG. 1  is a schematic diagram of the relevant electric, electronic, electromechanical and mechanical components of a motor vehicle equipped with a manual transmission and the present invention; 
           [0018]      FIG. 2  is a perspective view of a manual transmission shift lever and gear absolute position sensor assembly according to the present invention; 
           [0019]      FIG. 3  is a flow chart illustrating the logic and computational steps of the variable rev or speed matching method according to the present invention; and 
           [0020]      FIG. 4  is a graphical representation of the typical operation of the rev or speed matching achieved by the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0022]    With reference to  FIG. 1 , the relevant electric, electronic, electromechanical and mechanical components of a motor vehicle equipped with a manual transmission and the present invention are illustrated and generally designated by the reference number  10 . The significant mechanical components  10  include a prime mover  12  which may be a gasoline, Diesel or flex-fuel engine, or a hybrid or electric power plant. The prime mover  12  includes an output shaft  14  which drives a main friction clutch  16  which is typically engaged and dis-engaged by the vehicle operator (not illustrated). The main clutch  16 , which may be either mechanically or hydraulically operated, selectively provides drive torque to an input shaft  18  of a manual transmission  20 . The manual transmission  20  may be conventional and includes a housing  22  as well as shafts, gears, bearings and synchronizers (all not illustrated) which cooperatively provide, for example, four, five, six or more forward speeds or gear ratios and reverse. The transmission  20  includes an output shaft  24  which is coupled to a final drive assembly  26  which may include, for example, a propshaft, a differential assembly and a pair of drive axles. 
         [0023]    The components  10  also include a plurality of electric and electronic sensors which provide real time data to an engine control module (ECM) or similar device. An electronic speed sensor (tachometer)  32  is disposed in sensing relationship with the output shaft  14  of the prime mover  12  and provides a signal representing the instantaneous speed of the prime mover  12  to the control module  30 . Likewise, an optional transmission input shaft speed sensor (TISS)  34 , disposed in sensing relationship with the input shaft  18  of the transmission  20 , provides a signal representing the instantaneous speed of the input shaft  18  to the control module  30  and a transmission output speed sensor (TOSS)  36 , disposed in sensing relationship with the output shaft  24  of the transmission  20 , provides a signal representing the instantaneous speed of the output shaft  24  to the control module  30 . The transmission input shaft speed sensor  34  is optional because the speed of the input shaft  18  can be computed by simple multiplication from the known speed of the output shaft  24  and ratio of the currently selected or about to be selected gear. 
         [0024]    The transmission  20  includes a manual gear shift lever  42  which is manipulated by the vehicle operator to select a desired gear (or speed ratio) and is coupled to a gear absolute shift position sensor assembly  44  which preferably includes an application specific integrated circuit (ASIC)  46 , the data output or which is supplied to the control module  30  and which indicates the current position of the shift lever  42 . 
         [0025]    The mechanical and electro-mechanical components  10  include a clutch pedal  52  which is linked through a line  54  to the main clutch  16  and includes a clutch pedal position sensor  56  which provides a signal in a line  58  representing the instantaneous position of the clutch pedal  52  to the control module  30 . Likewise, a brake pedal  62  is linked to an anti-lock braking system (ABS) module  64  which provides braking signals and/or pressures to the four wheels of the vehicle and includes a brake pedal position sensor  66  which provides a signal in a line  68  representing the instantaneous position of the brake pedal  62  to the control module  30 . Additionally, in a typical and contemporary drive-by wire engine configuration, an accelerator or throttle pedal  72  includes a throttle pedal position sensor  74  which provides a signal in a line  76  representing the instantaneous position of the throttle pedal  72  to the control module  30 . This information, as well as other engine control signals according to the present invention, are provided in a line or lines  78  to one or more control devices  80  associated with the prime mover  12 . These control devices  80  adjust the speed of the prime mover  12  up or down and may include the throttle, active fuel management, that is, controlling the quantity of fuel to the engine or one or more cylinders, spark advance, as well as cam phasing, intake manifold tuning, port deactivation, exhaust gas recirculation, related methods and combinations thereof. 
         [0026]    The pedal position sensors  56 ,  66  and  74  may be any resistive, magnetic, PWM, linear variable displacement transformer (LVDT), permanent magnet linear contactless displacement (PLOD), Hall effect or other type of sensor providing an essentially analog, i.e., continuous, output from 0 to 100% of a variable as the pedal travels from an at rest (unactivated) position to a fully depressed (fully activated) position. 
         [0027]    The components  10  may also include a driver interface  82  which generally includes those switches, controls and devices under the supervision of and operated by the vehicle operator. For example, a switch of the driver interface  82  may manually activate and de-activate the present rev matching system. Additionally, the vehicle may include lateral and longitudinal accelerometers  84  which provide data in real time regarding the instantaneous acceleration in the X-Y plane the vehicle is experiencing as well as a steering angle sensor  86 . Preferably, data and signals from the driver interface  82 , the lateral and longitudinal accelerometers  84  and the steering angle sensor  86  are provided to a body control module (BCM)  88  or similar control module which acts as a centralized operational destination for such signals and data and which provides selected signals and data to the control module  30 . 
         [0028]    Referring now to  FIG. 2 , the manual gear shift lever  42  is a component of a shift linkage  90  that includes a shift handle  92  and a shift ball or pivot  94  and a link  96  which couples the motion of the gear shift lever  42  to a shaft  98  extending into the transmission  20  which translates both axially and rotationally. The shift lever  42  is moveable through a virtual or actual shift gate or “H” pattern which facilitates selection of, separates and creates tactile feedback for a number of forward gears or speed ratios and reverse. The gear absolute shift position sensor assembly  44  includes a first arc magnet or ring  102  and an axially spaced apart second arc magnet or ring  104 , both secured to the shaft  98 . In the neutral position of the shift linkage  90 , a first Hall effect sensor  106  is disposed proximate the first arc magnet  102  and a second Hall effect sensor  108  is disposed proximate the second arc magnet  104 . The outputs of the first Hall effect sensor  106  and the second Hall effect sensor  108  are fed directly to the application specific integrated circuit  46  which may be fabricated and integrated with the sensors  102  and  104  into a unitary device. 
         [0029]    Alternatively, a single arc magnet or ring and a proximate single three dimensional (3D) Hall effect sensor may be utilized in place of the two arc magnets  102  and  104  and the two Hall effect sensors  106  and  108 . In either case, it should be appreciated that the gear absolute position sensor assembly  44  provides instantaneous data or signals indicating the actual, current position of the shift lever  42  as it travels in the “H” shift pattern from one gear, through neutral, to another gear. That is, not only are data or signals regarding selected, discrete gears provided, but also data or signals indicating any and all current intermediate positions are provided. 
         [0030]    As an alternative to Hall effect sensors, anisotropic magneto resistance (AMR), giant magneto resistance (GMR), permanent magnet linear contactless displacement (PLOD), linear variable displacement transformer (LVDT), magneto elastic (ME) or magneto inductive (MI) sensors may be utilized. Further details of the gear absolute shift position sensor assembly  44  and the shift linkage  90  may be found in U.S. Pat. No. 8,739,647 B2 which is incorporated herein by reference. 
         [0031]    Referring now to  FIG. 3 , a program setting forth the steps of the method of variable rev or speed matching according to the present invention is designated by the reference number  120 . The program  120  begins with an initializing step  122  that clears certain registers and undertakes other normalizing activities and moves to an process step  124  that polls or reads one or more of the sensors such as the throttle position sensor  74 , the brake position sensor  66 , the clutch position sensor  56 , the gear absolute shift position sensor assembly  44 , the lateral and longitudinal accelerometers  84  and the steering angle sensor  86 . The program  120  then moves to a process or computation step  126  in which first, second or higher order derivatives are calculated for one or more of the current values provided by the throttle position sensor  74 , the brake position sensor  66 , the clutch position sensor  56 , the gear absolute shift position sensor assembly  44  and the lateral and longitudinal accelerometers  84 . Typically, the value of the steering angle sensor  86  is not differentiated as will be explained below. 
         [0032]    These first, second or higher order derivative values are then analyzed according to one of several schemes or hierarchies to arrive at a value or values that can be utilized to determine which of two, three or more operating modes should be selected to match the vehicle driver&#39;s current activity. For example, a first approach places primary importance on the data (derivatives) from the lateral accelerometer  84 , the clutch pedal sensor  56  and the gear shift sensor assembly  44  and less or little importance on the data (derivatives) from the remaining sensors. 
         [0033]    A second approach provides a weighted average of this data, that is, the data (derivatives) from each sensor are weighted by multiplying them by a distinct predetermined factor and the values summed. In this way, greater significance may be accorded to certain data such as that from the gear shift sensor assembly  44  or the brake pedal position sensor  66 , somewhat less to, for example, the accelerator pedal position sensor  74  or the lateral accelerometer  84  and less still to, for example, the longitudinal accelerometer  84  or the clutch pedal position sensor  56 . 
         [0034]    A third approach establishes one or more threshold values corresponding to the two, three or more operating modes of the system. When one or a defined number of the derivatives exceed a threshold value corresponding to one of the defined operational modes, that operational mode is selected by the program  120 . In yet another configuration, all or a selected plurality of the derivatives may simply be summed, the larger values contributing more to a total that is then utilized to determine the operating mode. It should be understood that undifferentiated data from the steering angle sensor  86 , when the indication is a significant or relatively marked front wheel angle to either the left or the right, may be utilized to override all other data and place the system in the least aggressive driving mode, i.e., “touring” in the present example. 
         [0035]    Given these above-discussed computations, the program  120  enters a decision point  130  which enquires whether the selected, weighted or summed derivative value or values are greater than a first, predetermined value or values. If it or they are, the decision point  130  is exited at YES and a flag is set in a process step  132  indicating the system is operating in the most aggressive mode, here denominated “TRACK.” Setting the flag in the step  132  may provide a signal to other systems and modules in the vehicle such as the body control module  88  and may illuminate an indicator light or icon on the dashboard or instrument panel informing the driver that the system is operating in the “TRACK” mode. Next, the current speeds of the prime mover  12  and the output shaft speed of the transmission  20  are read in a process step  134 . Also, any further activity of the shift lever  42  such as motion into or out of a gear and the speed of such motion is read. 
         [0036]    Then, another decision point  136  is entered and, depending upon the current activity of the shift lever  42 , the control module  30  determines that either an upshift or downshift is about to be undertaken. If an upshift is determined, the decision point  136  is exited at YES. If it is determined that a downshift is about to be undertaken, the decision point  136  is exited at NO. A YES response leads to a process step  140  which commands and completes a speed decrease of the prime mover  12  to achieve rev matching between the output shaft  14  of the prime mover  12  and the input shaft  18  of the transmission  20  within a first, shortest period of time. It should be understood that since the “TRACK” mode of operation is the most aggressive, this time period will be the shortest of the two, three or more rev matching times commanded and achieved by the present invention. While this time may change given the many variables between vehicles such as weight, horsepower, torque, transmission gears and drivetrain configuration, for example, for purposes of description and comparison a nominal value of 300 milliseconds and a range of from 200 to 400 milliseconds or more or less may be considered functional. 
         [0037]    The program  120  then terminates at an end point  142  and may be repeated according to iterative cycle times established by, for example, the control module  30  or other vehicle control module or system. 
         [0038]    If it is determined that an upshift is not taking place, that is, that a downshift is taking place, the decision point  136  is exited at NO which leads to a process step  144  which commands and completes a speed increase of the prime mover  12  to achieve rev matching between the output shaft  14  of the prime mover  12  and the input shaft  18  of the transmission  20  within the same first, shortest period of time. Again, it should be understood that since the “TRACK” mode of operation is the most aggressive, this time period will be the shortest of the two, three or more rev matching times commanded and achieved by the present invention. This first, shortest time period is subject to the same considerations recited above and will preferably have the same nominal value of 300 milliseconds and a range of from 200 to 400 milliseconds or more or less. 
         [0039]    The program  120  then concludes at the end point  142  and may be repeated according to iterative cycle times established by, for example, the control module  30  or other vehicle control module or system. 
         [0040]    Returning to the decision point  130 , if the selected, weighted or summed derivative value or values are less than a predetermined value or values, the decision point  130  is exited at NO and the program  120  enters another decision point  150  which enquires whether the selected, weighted or summed derivative value or values are greater than a second, smaller predetermined value or values. If it or they are, the decision point  150  is exited at YES and a flag is set in a step  152  indicating the system is operating in a less aggressive mode, here denominated “SPORT.” Setting the flag in the step  152  may provide a signal to other systems and modules in the vehicle such as the body control module  88  and may illuminate an indicator light or icon on the dashboard or instrument panel informing the driver that the system is operating in the “SPORT” mode. Next, the current speeds of the prime mover  12  and the output shaft speed of the transmission  20  are read in a step  154 . Any further activity of the shift lever  42  such as motion into or out of a gear may also be read. 
         [0041]    Then, another decision point  156  is entered and, depending upon the current activity of the shift lever  42 , the control module  30  determines that either an upshift or downshift is about to be undertaken. If an upshift is determined, the decision point  156  is exited at YES. If it is determined that a downshift is about to be undertaken, the decision point  156  is exited at NO. A YES response leads to a process step  160  which commands and completes a speed decrease of the prime mover  12  to achieve rev matching between the output shaft  14  of the prime mover  12  and the input shaft  18  of the transmission  20  within a second, longer period of time. It should be understood that since the “SPORT” mode of operation is less aggressive than the “TRACK” mode, this rev matching time period will be longer than the period of time in the “TRACK” mode but shorter than the rev matching times in the additional, still less aggressive mode or modes described subsequently. While this time may change given the many variables between vehicles such as weight, horsepower, torque, transmission gears and drivetrain configuration, for example, for purposes of description and comparison a nominal value of 500 milliseconds and a range of from 400 to 600 milliseconds or more or less may be considered functional. 
         [0042]    The program  120  then terminates at an end point  142  and may be repeated according to iterative cycle times established by, for example, the control nodule  30  or other vehicle control module or system. 
         [0043]    If it is determined that an upshift is not taking place, that is, that a downshift is taking place, the decision point  156  is exited at NO which leads to a process step  164  which commands and completes a speed increase of the prime mover  12  to achieve rev matching between the output shaft  14  of the prime mover  12  and the input shaft  18  of the transmission  20  within the same second, longer period of time. Again, it should be understood that since the “SPORT” mode of operation is less aggressive than the “TRACK” mode, this rev matching time period will be longer than the period of time in the “TRACK” mode but shorter than the rev matching times in the additional, still less aggressive mode or modes. This second, longer time period is subject to the same considerations recited above and will preferably have the same nominal value of 500 milliseconds and a range of from 400 to 600 milliseconds or more or less. 
         [0044]    The program  120  then concludes at an end point  142  and may be repeated according to iterative cycle times established by, for example, the control module  30  or other vehicle control module or system. 
         [0045]    Returning to the decision point  150 , if the selected, weighted or summed derivative value or values are less than the second, smaller predetermined value or values, the decision point  150  is exited at NO and a flag is set in a process step  172  indicating the system is operating in a still less aggressive mode, here denominated “TOURING.” As stated above, setting the flag in the step  172  may provide a signal to other systems and modules in the vehicle such as the body control module  88  and may illuminate an indicator light or icon on the dashboard or instrument panel informing the driver that the system is operating in the “TOURING” mode. Next, the current speeds of the prime mover  12  and the output shaft speed of the transmission  20  are read in a step  174 . Any further activity of the shift lever  42  such as motion into or out of a gear may also be read. 
         [0046]    Then, another decision point  176  is entered and, depending upon the current activity of the shift lever  42 , the control module  30  determines that either an upshift or downshift is about to be undertaken. If an upshift is determined, the decision point  176  is exited at YES. If it is determined that a downshift is about to be undertaken, the decision point  176  is exited at NO. A YES response leads to a process step  180  which commands and completes a speed decrease of the prime mover  12  to achieve rev matching between the output shaft  14  of the prime mover  12  and the input shaft  18  of the transmission  20  within a third, still longer (or longest) period of time. It should be understood that since the “TOURING” mode of operation is less aggressive than the “SPORT” mode, this rev matching time period will be longer than the period of time in the “SPORT” mode but shorter than the rev matching times in any additional, still less aggressive mode or modes. While this time may change depending upon the many variables between vehicles recited above, for purposes of description and comparison a nominal value of 800 milliseconds and a range of from 700 to 900 milliseconds or more or less may be considered functional. 
         [0047]    The program  120  then terminates at an end point  142  and may be repeated according to iterative cycle times established by, for example, the control nodule  30  or other vehicle control module or system. 
         [0048]    If it is determined that an upshift is not taking place, that is, that a downshift is taking place, the decision point  176  is exited at NO which leads to a process step  184  which commands and completes a speed increase of the prime mover  12  to achieve rev matching between the output shaft  14  of the prime mover  12  and the input shaft  18  of the transmission  20  within the same third, longest period of time. Again, it should be understood that since the “TOURING” mode of operation is less aggressive than the “SPORT” mode, this rev matching time period will be longer than the period of time in the “SPORT” mode but shorter than the rev matching times in any additional, still less aggressive mode or modes. This third, longest time period is subject to the same considerations recited above and will preferably have the same nominal value of 800 milliseconds and a range of from 700 to 900 milliseconds or more or less. 
         [0049]    The program  120  then concludes at an end point  142  and may be repeated according to iterative cycle times established by, for example, the control module  30  or other vehicle control module or system. 
         [0050]    It should be understood that while in the above description, three operating modes, “TRACK,” “SPORT,” and “TOURING” having decreasing degrees of aggressive rev matching have been disclosed and described, a system having additional rev matching time periods corresponding to four, five or more modes which provide correspondingly higher resolution of driver aggressiveness and prime mover response thereto are considered to be well within the scope of this invention and claims. In this regard, it should also be understood that the number of operating modes may be increased to the extent that the system operates essentially as a fully proportional system, matching, i.e., proportioning, the rev matching time period to the degree of driver aggressiveness sensed by the sensors  44 ,  56 ,  66 ,  74  and  84  and determined by the control module  30 . 
         [0051]    Referring now to  FIG. 4 , a graphic and qualitative representation of speed or rev matching is illustrated. The Y axis represents speed (RPM) of a prime mover  12  and the X axis represents time. The dark line  190  represents the speed of the prime mover  12  over time as a manual transmission  20  undergoes first a downshift at a point  192 . The present invention commands an increase in the speed of the engine or prime mover  12  represented by the line  194  beginning at the point  192  and the speed increases in the time interval  196  to match, within an acceptable tolerance represented by the dashed lines  198 , the speed of the input shaft  18  of the transmission  20 . Subsequently, an upshift begins at a point  202 . The present invention commands a decrease in the speed of the engine or prime mover  12  represented by the line  204  beginning at the point  202  and the speed decreases in the time interval  206  to match, within an acceptable tolerance represented by the dashed lines  208 , the speed of the input shaft  18  of the transmission  20 . 
         [0052]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.