Abstract:
A system and method for completing an automatic up-shift during an engine progressive governor event in a controller-assisted, manually shifted compound transmission system ( 10 ) and splitter shift control therefor. Auxiliary splitter section ( 16 B) shifts are automatically implemented by a splitter shifter ( 28 ) under commands ( 56 ) from a controller ( 48 ). The controller ( 48 ) overrides the engine governor control and controls engine torque to approach, and preferably reach a zero torque condition and bring the transmission to a splitter-neutral condition to enable an automatic up-shift when the splitter button has been selected or lever shift has been moved by the operator. Depending on the type of shift event, the transmission will automatically complete the upshift or the operator can manually complete the upshift after engine synchronization. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to automatic splitter shifting in a manually shifted compound transmission having a lever-shifted main section connected in series with an auxiliary splitter or splitter-and-range section. In particular, the present invention relates to a splitter control for transmissions of the type described for automatically implementing splitter up-shifts and/or splitter-and-range shifts during a manual lever shift when an engine governor event is encountered. 
     2. Description of the Related Art 
     Controller-assisted, manually shifted transmission systems are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,582,558; 5,755,639; 5,766,111; 5,791,189; 5,974,906; 5,989,155 and 6,015,366, the disclosures of which are incorporated herein by reference. 
     Compound transmissions having a range and/or combined range- and splitter-type auxiliary transmission section are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,754,665 and 5,390,561, the disclosures of which are incorporated herein by reference. 
     Transmissions having manually shifted main sections and automatically shifted splitter sections are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,435,212; 5,938,711; 6,007,455 and 6,044,721, the disclosures of which are incorporated herein by reference. 
     Compound transmissions having automatically implemented range shifting are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,911,787 and 5,974,906, the disclosures of which are incorporated herein by reference. 
     One technique for controlling engine fueling to thereby limit engine speed during manual gear shifting operations is commonly referred to as progressive shift governor control, as may be seen by reference to U.S. Pat No. 6,135,918, the disclosure of which is incorporated herein by reference. In progressive shift governor control, a linear engine speed limit, or governed engine speed limit, is typically established by specifying a first engine speed limit RPM 1  at a first vehicle speed VS 1 , and a second engine speed limit RPM 2  at a second vehicle speed VS 2 . The governed engine speed limit linearly increases from RPM 1  to RPM 2  between VS 1  and VS 2  and is held constant at RPM 2  beyond VS 2 , wherein RPM 2  is typically less than rated engine speed. Rated engine speed is defined for purposes of the present invention as the engine speed at which the engine produces an advertised horsepower value. 
     The purpose of progressive shift governor control is to gradually increase available engine speed (and thus more engine power) as vehicle speed increases between VS 1  and VS 2 , wherein typical values for VS 1  and VS 2  are 0.0 and 40 mph, respectively. This engine speed limiting scheme accordingly encourages the vehicle operator to manually shift gears at lower engine speeds than may otherwise occur, particularly in the lower transmission gears, thereby resulting in fuel savings associated with more efficient engine operation. 
     While the progressive shift governor control feature achieves the goal of encouraging vehicle operators to shift at lower engine speeds, it has certain drawbacks associated therewith. For example, when descending a grade or when hauling a heavily loaded trailer on level ground, providing a hard limit on available engine speed can hinder the drivability of the vehicle. One example of such hindered drivability may occur when attempting an automatic up-shift during an engine progressive shift governor event when descending a downhill grade, or moving at speed on level ground in a heavily loaded condition under low throttle, hereinafter characterized as a coasting condition or coasting. When in the coasting condition, the engine is being forced by the inertia of the vehicle to rotate at a higher speed than is commanded by the engine controller. Under the control of the progressive shift governor control, the governed engine speed limit may cause the vehicle to enter into a coasting condition in which the vehicle is driving the engine at a speed greater than that permitted by the progressive shift governor control, irrespective of the throttle position, resulting in a negative driveline torque. If the operator attempts to select the next higher gear by depressing the splitter button under such a negative torque condition, it may not be possible to shift gears due to the negative torque. As a result, the operator may be forced to break torque by depressing the clutch so that the transmission may be shifted to splitter-neutral and then to splitter high for the desired up-shift, thereby overcoming much of the benefit of an automated shift. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a manually shifted compound transmission with a splitter or combined splitter-and-range auxiliary section is provided, which will automatically shift the splitter section and/or automatically disengage and then reengage the splitter section as long as the lever position does not change. Logic rules are provided to determine when the splitter should be reengaged after the splitter is shifted to neutral. 
     The foregoing is accomplished in a manually shifted compound transmission having a lever-shifted main section connected in series with a splitter or combined splitter-and-range auxiliary section having an actuator for automatically implementing controller-initiated splitter shifts by sensing vehicle operating conditions. 
     Accordingly, one aspect of the present invention is to provide a method for controlling splitter shifting in a controller-assisted, manually shifted vehicular transmission system. The method comprises the steps of sensing if an upshift target gear ratio was selected prior to activation of engine governor control, determining a type of shift event, and if the sensing step is satisfied, controlling one of an engine speed and an engine torque to produce a zero torque condition and place the splitter auxiliary section in a splitter-neutral condition. 
     Another aspect of the present invention is to provide a method for controlling splitter shifting in a controller-assisted, manually shifted vehicular transmission system. The method comprises the steps of sensing if an upshift target gear ratio was selected prior to activation of engine governor control, determining a type of shift event, and overriding the engine governor control to produce a zero torque condition when said sensing step is satisfied, thereby placing the splitter auxiliary section in a splitter-neutral condition. 
     Yet another aspect of the present invention is to provide a new and improved splitter shift control for manually shifted compound transmissions having a splitter shifter for automatically implementing splitter shifts, wherein a controller includes logic rules for:
         sensing if an upshift target gear ratio was selected prior to activation of engine governor control;   determining a type of shift event; and   controlling one of an engine speed and an engine torque to produce a zero torque condition and place the splitter auxiliary section in a splitter-neutral condition when the upshift target gear ratio is selected prior to activation of engine governor control.       

     These and other aspects of the present invention will become apparent from a reading of the following description of the preferred embodiment taken in connection with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic illustration of an ECU-assisted compound mechanical transmission system advantageously utilizing the range shifting control of the present invention. 
         FIG. 2  is a chart illustrating the shift pattern and representative numerical ratios for the transmission of FIG.  1 . 
         FIG. 3  is a schematic illustration of the structure of the compound mechanical transmission of FIG.  1 . 
         FIG. 4  is a schematic illustration of a three-position splitter actuator for use with the transmission system of FIG.  1 . 
         FIGS. 5A and 5B  are schematic illustrations of a shift shaft position sensor mechanism for use in the system of FIG.  1 . 
         FIG. 6  is a schematic illustration, in flow chart format, of the splitter and governor control according to one aspect of the present invention. 
         FIG. 7  is a schematic illustration, in flow chart format, of the splitter and governor control according to another aspect of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A computer-assisted (i.e., microprocessor-based, controller-assisted) vehicular compound mechanical transmission system  10 , particularly well suited to utilize the range shift control of the present invention, may be seen by reference to  FIGS. 1-5B . 
     System  10  is of the type commonly utilized in heavy-duty vehicles, such as the conventional tractors of tractor/semi-trailer vehicles, and includes an engine, typically a diesel engine  12 , a master friction clutch  14  contained within a clutch housing, a multiple-speed compound transmission  16 , and a drive axle assembly (not shown). The transmission  16  includes an output shaft  20  drivingly coupled to a vehicle drive shaft  22  by a universal joint  24  for driving the drive axle assembly. The transmission  16  is housed within a transmission housing to which is directly mounted the shift tower of the shift lever assembly  30 . The present system is equally applicable to remotely mounted shift levers, as are used in cab-over-engine types of vehicles. 
       FIG. 2  illustrates a shift pattern for assisted manual shifting of a combined range-and-splitter-type compound transmission shifted by a manually operated shift lever. Briefly, the shift lever  31  is movable in the side-to-side or X—X direction to select a particular ratio or ratios to be engaged and is movable in the fore and aft or Y—Y direction to selectively engage and disengage the various ratios. The shift pattern may include an automatic range shifting feature and automatically selected and/or implemented splitter shifting, as is known in the prior art. Manual transmissions utilizing shift mechanisms and shift patterns of this type are well known in the prior art and may be appreciated in greater detail by reference to aforementioned U.S. Pat. Nos. 5,000,060 and 5,390,561. 
     Typically, the shift lever assembly  30  will include a shift finger or the like (not shown) extending downwardly into a shifting mechanism  32 , such as a multiple-rail shift bar housing assembly or a single shift shaft assembly, as is well known in the prior art and as is illustrated in aforementioned U.S. Pat. Nos. 4,455,883; 4,550,627; 4,920,815 and 5,272,931. 
     In the automatic range shifting feature, as the shift lever moves in the transition area between the middle leg (3/4-5/6) and the righthand leg (7/8-9/10) of the shift pattern, it will cross a point, AR, which will actuate a mechanical or electrical range switch, or will be sensed by a position sensor, to cause automatic implementation of a range shift. 
     The present invention also is applicable to transmission systems of the type utilizing range shift selector switches which are manually operated independent of shift lever position, as illustrated in aforementioned U.S. Pat. No. 5,222,404. 
     Shifting of transmission  16 , comprising main section  16 A coupled in series to auxiliary section  16 B, is semi-automatically implemented/assisted by the vehicular transmission system  10 , illustrated in  FIGS. 1-5B . Main section  16 A includes an input shaft  26 , which is operatively coupled to the drive or crank shaft  28  of the vehicle engine  12  by master clutch  14 , and output shaft  20  of auxiliary section  16 B is operatively coupled, commonly by means of a drive shaft  24 , to the drive wheels of the vehicle. The auxiliary section  16 B is a splitter type, preferably a combined range-and-splitter type, as illustrated in U.S. Pat. Nos. 4,754,665 and 5,390,561. 
     The change-gear ratios available from main transmission section  16  are manually selectable by manually positioning the shift lever  31  according to the shift pattern prescribed to engage the particular desired change gear ratio of main section  16 A. 
     The system may include sensors  30  (for sensing engine rotational speed (ES)),  32  (for sensing input shaft rotational speed (IS)), and  34  (for sensing output shaft rotational speed (OS)), and providing signals indicative thereof. As is known, with the clutch  14  (i.e., no slip) engaged and the transmission engaged in a known gear ratio, ES=IS=OS*GR (see U.S. Pat. No. 4,361,060). Accordingly, if clutch  14  is engaged, engine speed and input shaft speed may be considered as equal. Input shaft speed sensor  32  may be eliminated and engine speed (ES), as sensed by a sensor or over a data link (DL), substituted therefor. 
     Engine  12  is electronically controlled, including an electronic controller  36  communicating over an electronic data link (DL) operating under an industry standard protocol such as SAE J-1922, SAE J-1939, ISO 11898 or the like. Throttle position (operator demand) is a desirable parameter for selecting shifting points and in other control logic. A separate throttle position sensor  38  may be provided or throttle position (THL) may be sensed from the data link. Gross engine torque (T EG ) and base engine friction torque (T BEF ) also are available on the data link. 
     A manual clutch pedal  40  controls the master clutch  14 , and a sensor  42  provides a signal (CL) indicative of clutch-engaged or -disengaged condition. The condition of the clutch also may be determined by comparing engine speed to input shaft speed if both signals are available. An auxiliary section actuator  44  including a range shift actuator and a splitter actuator  46  is provided for operating the range clutch and the splitter section clutch in accordance with command output signals from ECU  48 . The shift lever  31  has a knob  50  which contains splitter selector switch  52  by which a driver&#39;s intent to initiate a splitter shift may be sensed. 
     System  10  may include a driver&#39;s display unit  54  including a graphic representation of the six-position shift pattern with individually lightable display elements  56 ,  58 ,  60 ,  62 ,  64  and  66 , representing each of the selectable engagement positions. Preferably, each half of the shift pattern display elements (i.e.,  58 A and  58 B) will be individually lightable, allowing the display to inform the driver of the lever and splitter position for the engaged ratio. 
     The system includes a control unit or ECU  48 , preferably a microprocessor-based control unit of the type illustrated in U.S. Pat. Nos. 4,595,986; 4,361,065 and 5,335,566, the disclosures of which are incorporated herein by reference, for receiving input signals  68  and processing same according to predetermined logic rules to issue command output signals  70  to system actuators, such as the splitter section actuator  46 , the engine controller  36 , the range shift actuator and/or the display unit  54 . A separate system controller may be utilized, or the engine controller ECU  36  communicating over an electronic data link may be utilized. 
     As shown in U.S. Pat. Nos. 5,651,292 and 5,661,998 (the disclosures of which are incorporated herein by reference), the splitter actuator  46  is, preferably, a three-position device, allowing a selectable and maintainable splitter section neutral. Alternatively, a “pseudo” splitter-neutral may be provided by deenergizing the splitter actuator when the splitter clutch is in an intermediate, non-engaged position. 
     The structure of the  10 -forward-speed combined range-and-splitter-type transmission  16  is schematically illustrated in FIG.  3 . Transmissions of this general type are disclosed in aforementioned U.S. Pat. Nos. 5,000,060; 5,370,013 and 5,390,561. 
     Transmission  16  includes a main section  16 A and an auxiliary section  16 B, both contained within a housing including a forward end wall  16 C, which may be defined by the clutch housing, and a rearward end wall  16 D, but (in this particular embodiment) not an intermediate wall. 
     Input shaft  26  carries input gear  76  fixed for rotation therewith and defines a rearwardly opening pocket wherein a reduced diameter extension of output shaft  20  is piloted. A non-friction bushing or the like may be provided in the pocket or blind bore. The rearward end of input shaft  26  is supported by bearing  78  in front end wall  16 C, while the rearward end of output shaft  20  is supported by bearing assembly  80  in rear end wall  16 D. 
     The mainshaft  82 , which carries mainshaft clutches  84  and  86 , and the mainshaft splitter clutch  88  is in the form of a generally tubular body having an externally splined outer surface and an axially extending through bore for passage of output shaft  20 . Shift forks  90  and  92  are provided for shifting clutches  84  and  86 , respectively (see FIG.  5 A). Mainshaft  82  is independently rotatable relative to input shaft  26  and output shaft  20  and preferably is free for limited radial movement relative thereto. 
     The main section  16 A includes two substantially identical main section countershaft assemblies  94 , each comprising a main section countershaft  96  carrying countershaft gear pairs  98 ,  102 ,  104  and  106  fixed thereto. Gear pairs  98 ,  102 ,  104  and  106  are constantly meshed with input gear  76 , mainshaft gears  108  and  110  and an idler gear (not shown), which is meshed with reverse mainshaft gear  112 , respectively. One of the countershaft assemblies  94  may include a gear  100 , commonly known as a power take-off gear. 
     Main section countershaft  96  extends rearwardly into the auxiliary section, where its rearward end is supported directly or indirectly in rear housing end wall  16 D. 
     The auxiliary section  16 B of transmission  16  includes two substantially identical auxiliary countershaft assemblies  114 , each including an auxiliary countershaft  116  carrying auxiliary countershaft gears  118 ,  120  and  122  for rotation therewith. Auxiliary countershaft gear pairs  118 ,  120  and  122  are constantly meshed with splitter gear  124 , splitter/range gear  126  and range gear  128 , respectively. Splitter clutch  88  is fixed to mainshaft  82  for selectively clutching either gear  124  or  126  thereto, while synchronized range clutch  130  is fixed to output shaft  20  for selectively clutching either gear  126  or gear  128  thereto. 
     Auxiliary countershafts  116  are generally tubular in shape, defining a through bore for receipt of the rearward extensions of the main section countershafts  96 . Bearings or bushings are provided to rotatably support auxiliary countershaft  116  on main section countershaft  96 . 
     The splitter jaw clutch  88  is a double-sided, non-synchronized clutch assembly which may be selectively positioned in the rightwardmost or leftwardmost positions for engaging either gear  126  or gear  124 , respectively, to the mainshaft  82  or to an intermediate position wherein neither gear  124  or  126  is clutched to the main shaft. Splitter jaw clutch  88  is axially positioned by means of a shift fork  98  controlled by a three-position actuator, such as a piston actuator, which is responsive to a driver selection switch such as a button or the like on the shift knob, as is known in the prior art and to control signals from ECU  48  (see U.S. Pat. No. 5,661,998). Two-position synchronized range clutch assembly  130  is a two-position clutch which may be selectively positioned in either the rightwardmost or leftwardmost positions thereof for selectively clutching either gear  128  or  126 , respectively, to output shaft  20 . Clutch assembly  130  is positioned by means of a shift fork (not shown) operated by means of a two-position piston device. Either piston actuator may be replaced by a functionally equivalent actuator, such as a ball screw mechanism, ball ramp mechanism or the like. 
     By selectively axially positioning both the splitter clutch  88  and the range clutch  130  in the forward and rearward axial positions thereof, four distinct ratios of mainshaft rotation to output shaft rotation may be provided. Accordingly, auxiliary transmission section  16 B is a three-layer auxiliary section of the combined range and splitter type providing four selectable speeds or drive ratios between the input (mainshaft  82 ) and output (output shaft  20 ) thereof. The main section  16 A provides a reverse and three potentially selectable forward speeds. However, one of the selectable main section forward gear ratios, the low-speed gear ratios associated with mainshaft gear  110 , is not utilized in the high range. Thus, transmission  16  is properly designated as a “(2+1)×(2×2)” type transmission providing nine or ten selectable forward speeds, depending upon the desirability and practicality of splitting the low gear ratio. 
     Splitter shifting of transmission  16  is accomplished responsive to initiation by a vehicle operator-actuated splitter button  52  or the like, usually a button located at the shift lever knob, while operation of the range clutch shifting assembly is an automatic response to movement of the gear shift lever between the central and rightwardmost legs of the shift pattern, as illustrated in FIG.  2 . Alternatively, splitter shifting may be automated (see U.S. Pat. No. 5,435,212). Range shift devices of this general type are known in the prior art and may be seen by reference to aforementioned U.S. Pat. Nos. 3,429,202; 4,455,883; 4,561,325 and 4,663,725. 
     To protect the range synchronizers, a properly executed range shift should occur in the sequence of (i) disengaging the main section by shifting to main section neutral, (ii) then initiating and completing the range section shift, and (iii) then, after the range section shift is completed, engaging the main section in the appropriate ratio. 
     As is known in the prior art, range clutch damage, also called “range synchronizer burnout,” is most likely to occur in three situations: (i) if the main section is engaged prior to completion of a range up-shift, (ii) if the main section is engaged prior to completion of a range downshift, or (iii) if a range downshift is attempted at too high a vehicle speed. As will be discussed below, the range shift control of the present invention is effective to minimize or eliminate damage under such occurrences and to allow rapid and dependable completion of permissible range shifts. 
     Although the present invention is illustrated in the embodiment of a compound transmission not having an intermediate wall, the present invention is equally applicable to transmissions of the type illustrated in aforementioned U.S. Pat. Nos. 4,754,665; 5,193,410 and 5,368,145. 
     According to the present invention, and as more fully described in aforementioned U.S. Pat. No. 5,651,292, the interengaging clutch teeth provided on splitter clutch  88  and on splitter gear  124  and splitter/range gear  126  are of a relatively large backlash (i.e., about 0.020-0.060 inches for a 3.6-inch pitch diameter clutch), which will assure that almost any attempted splitter shift under full force will be completed. 
     The clutch  88  is moved by a shift fork  98  attached to the piston rod  140  of the piston actuator assembly  142  (see FIG.  4 ). Actuator assembly  142  may be a conventional three-position actuator (see U.S. Pat. No. 5,054,591, the disclosure of which is incorporated herein by reference) or an actuator of the type illustrated in U.S. Pat. Nos. 5,682,790 or 5,661,998 (the disclosures of which are incorporated herein by reference), wherein pulse width modulation of a selectively pressurized and exhausted chamber  144  may be used to achieve the three splitter positions (L, N, H) of the shift fork. 
     Preferably, the splitter clutch actuator  142  will be capable of applying a variable force, such as by pulse width modulation, of supply pressure. A force lesser than full force may be utilized when disengaging and/or when synchronous conditions cannot be verified. 
     The controller  48  is provided with logic rules under which, if the main section is engaged, a shift from splitter neutral into a selected target splitter ratio is initiated such that, under normal conditions, including proper operator fuel control, the synchronous error (which is equal to input shaft rotational speed minus the product of output shaft rotational speed and transmission target gear ratio) is expected to be equal to or less than a value selected to give smooth, high-quality shifts ((IS-(OS*GR))=ERROR≦REF). The timing is done in regard to sensed/expected shaft speeds, shaft acceleration/deceleration and actuator reaction times. 
     In certain situations, the logic rules will recognize operating conditions wherein the preferred synchronous window (i.e., IS=(OS*GR)±60 RPM) must be expanded to accomplish a splitter shift, even at the expense of shift quality. These situations, usually associated with up-shifts, include if shifting attempted at low engine speeds wherein expected engine speed at shift completion will be undesirably low, if deceleration of the output shaft is relatively high (dOS/dt&lt;REF), if the deceleration of the engine is relatively low (dES/dt&gt;REF) and/or if the absolute value of the synchronous error is not approaching the normal value at an acceptable rate. 
     The position of the shift lever  31  or of the shifting mechanism  32  controlled thereby may be sensed by a position sensor device. Various positioning sensing assemblies are known in the prior art, with a preferred type illustrated in allowed U.S. Pat. No. 5,743,143, assigned to the assignee of this application, the disclosure of which is incorporated herein by reference. 
     Referring to  FIGS. 5A and 5B , shifting mechanism  32  is illustrated as a single shift shaft device  160  having a shaft  162  which is rotatable in response to X—X movements of shift lever  31  and axially movable in response to Y—Y movements of shift lever  31 . Mechanisms of this type are described in detail in aforementioned U.S. Pat. No. 4,920,815. 
     Shift shaft  162  carries the main section shift forks  90  and  92  for selective axial movement therewith and a shift block member  164  for receiving a shift finger or the like. A pair of coils  166  and  168  provides a pair of signals (collectively GR) indicative of the axial and rotational position of shaft  162  and, thus, of shift lever  31  relative to the shift pattern illustrated in FIG.  2 . Preferably, the rate of change of position (dGR/dt) also may be determined and utilized to enhance shifting of the system  10 . 
     By way of example, referring to  FIG. 2 , if shift lever position can be sensed, the need for a fixed switch or the like at point AR to sense a required initiation of a shift between low range and high range is eliminated. Further, as physical switches are no longer required, the shift pattern position at which a range shift will be commanded can be varied, such as to points  180 ,  182  or  184 , to enhance system performance under various operating conditions. 
     If in first (1st) through fourth (4th), a shift into high range is unlikely, and the auto range shift initiation point may be moved to position  184  (away from the expected shift lever path) to prevent inadvertent actuation of a range shift. If in sixth (6th) with a high engine speed, a shift into high range is likely and moving the auto range initiation point to position  180  will allow for a quicker initiation of a range shift. 
     According to the present invention, the operator is allowed to control engine fueling unless the current vehicle operating conditions indicate that his/her operation of the throttle pedal will not allow the jaw clutches associated with the current target ratio to engage. If operating conditions, including operator setting of the throttle pedal, indicate that the operator will complete a splitter shift into target ratio, the engine will be fueled in accordance with operator throttle setting. If not, automatic engine fueling may occur. If the splitter section does engage prior to the main section, as is preferred, the operator will remain in complete control of engine fueling to complete the shift by engaging the main section. 
     The state of engagement (i.e., engaged or neutral) of the main transmission section  16 A is an important control parameter for system  10 . By way of example, if main section neutral is sensed, the splitter may be commanded to a full force engagement, regardless of the existence or absence of appropriate synchronous conditions. Also, if the main section is engaged while the splitter is in neutral, the system will not cause splitter engagement until an appropriate substantial synchronous condition is sensed and may then initiate automatic fuel control if required. Of course, it is important to prevent or minimize false determinations of main section neutral and/or engaged conditions. 
     Referring to  FIG. 2 , a first narrow band  202  and a second wider band  204  of vertical displacements from a center position  200  are utilized to determine if the main section is or is not in neutral. If the transmission main section is not confirmed as being in main section neutral, the neutral confirmation band will be the narrower band  202 . This will assure that the main section  16 A is truly in neutral before declaring a main section neutral condition. If the transmission main section  16 A is confirmed as being in neutral, the neutral confirmation band will be the wider band  204 . This assures that mere overshooting of neutral or raking of main section jaw clutches will not be incorrectly interpreted as a main section engaged condition. 
     Sensing the shift lever at point  206  will always be interpreted as main section neutral, and sensing the shift lever at point  208  will always be interpreted as main section engaged. However, if the shift lever is sensed at point  210 , this will not cause a previous determination of a neutral or engaged condition to change. 
     Vehicle operating conditions other than or in addition to currently engaged or neutral condition of the main section  16 A may be used to vary the width of the neutral sensing bands. 
     In the prior art automated mechanical transmission systems, when it was necessary to significantly reduce engine speed to synchronize for engaging an up-shift target gear ratio, the engine was commanded by controller  48  to reduce driveline torque to enable a shift to neutral, and to subsequently bring the engine speed to a synchronous target engine speed (ES=ES TARGET ). Certain engines of certain manufacturers also implement an engine governor control of the engine speed, such as a progressive shift engine governor control. The progressive shift engine governor control, in one embodiment, is stored or embedded in the form of logic steps within controller  36 . The engine deceleration rate that occurs is dependent upon the engine manufacturer&#39;s implementation of its speed control mode and can sometimes be undesirably slow, as the speed control mode attempts to smoothly ramp engine speed to the target engine speed limit. “Ramped” is used to mean a modulated rate of deceleration less than the rate of unmodulated engine deceleration. 
     According to the present invention, Applicants have discovered that when a significant decrease in engine speed is required to execute a clutchless or float shift into an up-shift target gear ratio, and the vehicle is operating in a coasting condition, the progressive shift governor control may prevent shifting. Shifting may be prevented if transmission  16  is sustaining a torque load. The transmission will commonly be sustaining a negative torque load in the coasting condition. This negative torque condition undesirably induces a force within transmission  16  resisting a shift to neutral. To permit shifting the transmission, the driver is required to break the engine torque, typically by using the master clutch  14 . Alternatively, if the operator is aware of the potential for the above-described condition, the operator may elect to shift earlier in an attempt to complete a clutchless, automation-assisted shift. However, this attempt to shift early may result in a lower than desired engine speed. 
     According to one aspect of the invention, as shown in  FIG. 6 , a protocol for controlling splitter shifting in a controller-assisted manually shifted vehicular transmission system  10  is described. The protocol, in one embodiment, is stored or embedded in the form of logic steps within ECU  48 . The protocol begins at step  600 , and at step  602 , the engine governor control, such as a progressive shift engine governor control, is activated. Next, the control unit or ECU  48  determines whether a splitter shift is selected and an automatic up-shift is probable, and whether a coasting condition is present in step  604 . A splitter shift is selected when the operator depresses the splitter button. For example, the operator may select a splitter shift when shifting from first (1 st ) to second (2 nd ) to automatically perform a float shift without using the master clutch  14 . Whether an automatic up-shift is probable depends on vehicle conditions, such as engine speed and vehicle speed. For example, an up-shift is probable when the engine speed is near maximum engine speed. A coasting condition exists when the vehicle is driving the engine, rather than the engine driving the vehicle, irrespective of the throttle position. If a splitter shift has not been selected, or if neither an up-shift is probable, nor coasting is present, then the protocol proceeds to step  610  and standard shift protocols are invoked. The up-shift is completed in step  612 , and the protocol ends at step  614 . 
     If the conditions of step  604  are satisfied, the protocol proceeds to step  606  in which ECU  48  determines whether the shift initiation indicators are true, that is the indicators are consistent with the conditions appropriate for shifting, such as the splitter button being depressed, the throttle pedal is no longer being depressed by the operator, or the like. If not, then the protocol proceeds to steps  610 ,  612  and  614 . If so, then the protocol proceeds to step  608  in which the transmission controller  48  overrides the engine governor control and increases engine torque such that the engine torque approaches, and preferably reaches a zero torque condition to enable the splitter auxiliary section to be shifted to a splitter-neutral condition required for the operator to engage an up-shift target gear ratio. By definition, increasing the engine torque is to overcome the negative torque condition of the transmission  16  by controlling the engine to reduce an absolute magnitude of torque sustained by the transmission. Ideally, the torque magnitude approaches, and preferably reaches zero. 
     In the coasting condition, the engine may be tending to slow down the vehicle and the engine speed may increase when the absolute magnitude of engine torque moves toward the engine zero torque condition. For example, to increase engine torque and/or engine speed, the controller  54  may send a message through the data link DL ( FIG. 1 ) to send a controlled amount of fuel to the engine  12 . Once the engine zero torque condition is reached, the established shift protocol in step  610  can be used to engage an up-shift target gear ratio in step  612 . The protocol then ends in step  614 . 
     According to another aspect of the invention, as shown in  FIG. 7 , an alternative protocol for controlling splitter shifting in a controller-assisted manually shifted vehicular transmission system  10  is described. The protocol begins at step  700 . At step  702 , the engine governor control, such as a progressive shift engine governor control, is activated. Next, a determination is made as to whether the operator has selected an up-shift by the position of the splitter button in step  704 . If not, then the protocol proceeds to step  722  and ends at step  716 . If so, then a determination is made as to whether the up-shift was selected prior to the activation of the governor control in step  706 . If not, then the protocol proceeds to step  720  and determines whether the shift initiation indicators are true, similar to step  606  of FIG.  6 . If so, the controller  48  overrides the governor control and increases engine torque such that the engine torque approaches, and preferably reaches a zero torque condition to enable the splitter auxiliary section to be shifted to a splitter-neutral condition required for the operator to engage an up-shift target gear ratio in step  710 , similar to step  608  of FIG.  6 . If the determination is made in step  720  that the shift initiation indicators are false, then the protocol proceeds to step  722  and the transmission system  10  does not override the governor control and exits in step  716 . 
     If in step  706  a determination was made that up-shift was selected prior to the activation of the governor control, then the protocol proceeds to step  708  and a determination is made whether the operator has selected an automatic up-shift by depressing the splitter button to shift from, for example, first (1 st ) to second (2 nd ), and perform a float shift without using the master clutch  14 . If so, then the protocol proceeds to steps  710  through  716 . If not, then a determination is made in step  718  whether the operator has selected a manual compound shift. A manual compound shift occurs when the operator moves the shift lever, for example, from second (2 nd ) to third (3 rd ). If not, then the protocol proceeds to step  720  for a determination of whether the shift initiation indicators are true. If so, then the protocol proceeds to step  710  and the controller  48  overrides the governor control and increases engine torque such that the engine torque approaches, and preferably reaches a zero torque condition to enable the splitter auxiliary section to be shifted to a splitter-neutral condition required for the operator to engage an up-shift target gear ratio. Then, the protocol proceeds to step  712  through  716 , similar to steps  610  through  614  of FIG.  6 . 
     As can be seen with both aspects of the invention described in  FIGS. 6 and 7 , the transmission system  10  temporarily overrides the engine governor control, for example, a progressive shift governor control, and increases engine torque such that the engine torque approaches, and preferably reaches a zero torque condition to enable the splitter auxiliary section to be shifted to a splitter-neutral condition required for the operator to engage an up-shift target gear ratio. This overriding feature can be accomplished, for example, by the controller  48  sending a message through the data link DL to send a controlled amount of fuel to the engine  12 , thereby temporarily overriding the engine governor control. Once the zero torque condition is reached, an established shift protocol can be used to engage the up-shift target gear ratio. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.