1. Field of the Invention
The present invention relates to a method/system for utilizing a position sensor, such as a sensor for sensing the Y-Y position of a shift member in a vehicular transmission shifter, to determine the mode of engine fueling to be utilized to allow a shift to neutral without requiring disengagement of the vehicle master clutch. More particularly, the present invention relates to an adaptive technique utilizing a sensed rate of change in the Y-Y position of a shift member, such as a shift lever or shift finger movable in an xe2x80x9cH-typexe2x80x9d shift pattern or of an automated shift actuator, to determine if a forced torque reversal routine is necessary to allow a shift to neutral.
The present invention also relates to a method/system for causing engine torque to equal a value calculated to provide a zero driveline torque wherein, engine torque is changed at a rate which is a function of sensed throttle pedal position and/or engaged ratio.
2. Description of the Prior Art
Manually operated shift levers and X-Y shifters for moving a shift member, such as a shift finger or the like, in an H-type shift pattern are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,481,170; 5,281,902; 4,899,607; 4,821,590; 4,784,007; 4,455,883; and 4,515,029, the disclosures of which are incorporated herein by reference.
Position sensors of the discrete position type for sensing discrete X-Y positions of a shift member in an H-type shift pattern are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,817,468 and 4,718,307. Sensors providing analog or digital signals, the magnitude of which are representative of the X-X and/or Y-Y position of a shift member in an H-type shift pattern and/or shaft force, are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,911,787; 5,743,143; 5,481,170; and; 5,950,491, the disclosures of which are incorporated herein by reference. Sensors for sensing the position of other shift members, such as pistons, ball screw members and the like are also known in the prior art.
Fully or partially automated mechanical transmission systems that, upon determining that a shift from a currently engaged ratio into neutral and than into a target ratio is desirable, will, while maintaining the vehicle master friction clutch engaged, initiate automatic fuel control to cause reduced torque across the jaw clutches to be disengaged, are also known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,850,236; 5,582,558; 5,735,771; 5,775,639; and 6,015,366, the disclosures of which are incorporated herein by reference.
These systems include systems that attempt to fuel the engine to achieve a zero driveline torque, see U.S. Pat. No. 4,593,580, the disclosure of which is incorporated herein by reference, and systems that fuel the engine to force one or more torque reversals, see U.S. Pat. No. 4,850,236.
Systems utilizing the engine fueling technique of forced torque reversals, especially repeated forced torque reversals, provide a highly reliable routine for allowing a shift to neutral, but may provide a somewhat less than desirable shift feel. Systems utilizing the engine fueling technique of aiming and attempting to remain at zero driveline torque provide a relatively high quality shift fuel, but did not provide desirable reliability of allowing an engaged jaw clutch to be acceptably disengaged.
In accordance with the present invention, an adaptive engine fueling control is provided which, based upon a sensed movement, preferably a rate of movement of a shift member, such as a shift lever in the Y-Y direction or the like, will utilize engine fueling to achieve the most appropriate (a) of aiming at a zero driveline torque, (b) or causing torque bumps to force torque reversals across the jaw clutch to be disengaged, or (c) a combination of thereof.
In a preferred embodiment, the above is accomplished by, upon determining that a shift into transmission neutral is required, causing the engine to be fueled to cause an output (flywheel) torque determined to cause a substantially zero driveline torque while monitoring shift member position. After a period of time, if the rate of change of the shift member position is greater than a reference value, than the desired substantially zero torque condition has been achieved (as expressed by the operator""s ability to move the shift lever toward the Y-Y neutral position) and a torque bump routine to forced torque reversals is not required. If however, the shift member rate of movement is not at least equal to the reference value, than the torque bump routine may be necessary and will be initiated.
Accordingly, it is an object of the present invention to provide an improved method/system for adaptively controlling engine fueling to allow a shift into neutral without requiring master friction clutch to remain disengaged. The adaptive engine fuel control is a function of sensed change or rate of change of a shift member position, such as, for example, the Y-Y position of a shift member movable in an H-type shift pattern.
This and other objects and advantages 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.