Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1999-05-17
2001-03-06
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S090000, C701S053000, C701S051000, C477S034000, C477S108000, C477S115000, C477S110000, C290S04000F, C290S00100C
Reexamination Certificate
active
06199004
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system and method to control an internal combustion engine coupled to a torque converter and in particular to adjusting engine output to control torque converter slip, or speed ratio.
BACKGROUND OF THE INVENTION
Internal combustion engines must be controlled in many different ways to provide acceptable driving comfort during all operating conditions. Some methods use engine output, or torque control where the actual engine torque is controlled to a desired engine torque through an output adjusting device, such as with an electronic throttle, ignition timing, or various other devices. In some cases, such as during normal driving conditions, the desired engine torque is calculated from the amount of depression of an accelerator pedal. In other conditions, such as idle speed control, the desired engine torque is calculated based on a speed error between actual engine speed and a desired engine speed. Some attempts have been made to use this torque control architecture to improve driveability during deceleration conditions, such as when a driver releases their foot to the minimum accelerator pedal position, known to those skilled in the art as a tip-out. During a tip-out, the driver is indicating a desire for reduced engine output.
One system that attempts to use speed control during deceleration conditions operates the engine in such a way as to maintain constant engine speed during slow moving or stopped conditions. In this system, the engine is controlled to a constant speed taking into account the loading from the torque converter. The loading from the torque converter is calculated based on the engine speed and turbine speed. Engine speed can be controlled to a constant level during deceleration to adsorb energy from the vehicle and assists in vehicle braking. Further, as turbine speed increases, the desired engine speed is reduced to provide even more engine braking. Such a system is described in D.E. 4321413A1.
The inventors herein have recognized a disadvantage with the above invention. In particular, the accelerator pedal is released and subsequently engaged, the prior art system exhibits poor driveability due transmission gears lash. For example, when the engine transitions from exerting a positive torque to exerting a negative torque (or being driven), the gears in the transmission separate at the zero torque transition point. Then, after passing through the zero torque point, the gears again make contact to transfer torque. This series of events produces an impact, or clunk, resulting in poor driveability and customer disatisfaction. In other words, the engine first exerts a positive torque through the torque converter onto the transmission input gears to drive the vehicle. Then, when using the prior art approach during deceleration, the engine is driven by the torque from the transmission through the torque converter. The transition between these to modes is the point where the engine is producing exactly zero engine brake torque. Then, at this transition point, the gears in the transmission separate because of inevitable transmission gear lash. When the gears again make contact, they do so dynamically resulting in an undesirable impact.
This disadvantage of the prior art is exacerbated when the operator returns the accelerator pedal to a depressed position, indicating a desire for increased engine torque. In this situation, the zero torque transition point must again be traversed. However, in this situation, the engine is producing a larger amount of torque than during deceleration because the driver is requesting acceleration. Thus, another, more severe, impact is experienced due to the transmission lash during the zero torque transition.
SUMMARY OF THE INVENTION
An object of the invention claimed herein is to provide an engine output control system for preventing or easing transitions through the transmission lash zone.
The above object is achieved, and problems of prior approaches overcome, by a vehicle control method for a vehicle having an internal combustion engine coupled to a torque converter having a torque converter speed ratio determined by dividing torque converter output turbine speed by engine speed, the torque converter coupled to a transmission. The method comprises the steps of creating a desired engine speed as a function of and greater than torque converter turbine speed so that a positive torque is applied to the transmission thereby preventing transmission gear separation, and adjusting an engine output amount so that an actual engine speed approaches said desired engine speed.
By using signals already available to provide real-time feedback control positive torque will be applied to the transmission to eliminate the lash zone. In other words, the present invention utilizes the torque converter characteristics in the following way. Because these measurements are readily available, a simple engine speed controller can be developed that will guarantee positive torque application to the transmission. In the simplest form, according to the present invention, this amounts to controlling engine torque to keep the engine speed greater than the torque converter turbine speed. Thus, during tip-out conditions, driveability problems associated with traversing the zero torque lash point are avoided. Further, by using turbine speed to generate the desired engine speed, thus guaranteeing a positive torque, effects from road grade, vehicle mass, temperature, and other factors are inherently considered without complexity or addition computation.
An advantage of the above aspect of the invention is improved driveability.
Another advantage of the above aspect of the invention is improved customer satisfaction.
Other objects, features and advantages of the present invention will be readily appreciated by the reader of this specification.
REFERENCES:
patent: 5058013 (1991-10-01), Iwatsuki et al.
patent: 5325740 (1994-07-01), Zhang et al.
patent: 5403247 (1995-04-01), Yagi
patent: 5580334 (1996-12-01), Minowa et al.
patent: 5797110 (1998-08-01), Braun et al.
patent: 5909094 (1999-06-01), Yamada et al.
patent: 5938712 (1999-08-01), Ibamoto et al.
patent: 6014604 (2000-01-01), Kuroiwa et al.
patent: 6067494 (2000-05-01), Noda et al.
patent: 4321413A1 (1995-01-01), None
Kotwicki Allan Joseph
Russell John David
Cuchlinski Jr. William A.
Ford Global Technologies Inc.
Hernandez Olga
Russell John D.
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