Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-01-27
2001-10-23
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S085000, C701S090000, C303S140000, C303S146000
Reexamination Certificate
active
06308127
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to apparatus and method for controlling a driving force for a vehicle. The present invention particularly relates to control apparatus and method in which an engine (output) torque is controlled in such a manner that the engine torque provides a driver's demanding torque in accordance with a driver's intention (accelerator operation situation) when no driving force control is executed, the engine torque provides a target engine torque derived from a predetermined driving force control when the driving force control is executed and which have improved reliabilities of control.
b) Description of the Related Art
It is well known that, in a case where excessive slip occurs on drive wheels during a vehicular acceleration, an opening angle of an engine throttle valve is not determined in a direct accordance with a manipulation of an acceleration by a vehicular driver but a traction control is executed such that the opening angle of the throttle valve and/or the number of engine cylinders to which an air-fuel mixture fuel supply is cut off is controlled on a basis of a target engine output torque which is derived so that the slip is suppressed and the driving force is stably transmitted on a road surface. The traction control system described above is normally abbreviated as TCS.
In addition to an engine controller which is enabled to adjust over an engine driving force to adjustably increase or decrease the opening angle of the throttle valve and the number of engine cylinders for which the fuel supply out-off is carried out, a TCS controller is provided. The TCS controller determines a slip condition of drive wheels on the basis of a difference in road wheel velocities between the drive wheels and non-drive wheels, executes the driving force control in a case where the slip condition is excessively large, calculates an appropriate opening angle of the engine throttle valve such as to enable the suppression of the excessive slip, and outputs a signal representing the calculated opening angle of the throttle valve to an engine (output) controller.
SUMMARY OF THE INVENTION
The engine controller compares the opening angle of the throttle valve to achieve the driver's demanding torque in accordance with the accelerator manipulation by the driver and that supplied from the TCS controller to achieve a target engine torque, select either one of these opening angle values which is smaller than the other (viz., either one which provides a smaller engine torque and, so-called, a select-low), and adjusts the actual opening angle of the throttle valve on the basis of the selected opening angle of the throttle valve.
As described above, the engine controller can prevent the engine torque from becoming excessively large to develop an excessive wheel slip, when the smaller value of either the driver's demanding torque or the target engine torque supplied from the TCS controller.
Furthermore, another TCS controller has been proposed in which, in a case where the slip condition of the drive wheels is not determined to be excessive (during the non-execution of the driving force), a maximum value is outputted as a signal representing the opening angle of the throttle valve. In other words, even if the value of the signal representing the opening angle of the throttle valve provides the maximum value, the selection method of the select-low has been adopted in the engine controller so that the opening angle of the engine throttle valve is selected which is in accordance with the driver's demanding torque. Therefore, the engine driving force will not becomes excessive irrespective of the accelerator manipulation by the vehicular driver, during the non-execution of the driving force since the opening angle of the throttle valve in accordance with the driver's demanding torque.
It is assured that if the above-described selection method (select-low) is adopted in the engine controller to which the output signal from the TCS controller is supplied, the excessive torque of the engine can be prevented and a possibility of generating the excessive slip during the vehicular acceleration can be reduced.
However, the inventor has discovered according to the inventor's research that the selection method of the select-low is inconvenient for the driving forces control. That is to say, the select-low method always selects either one of these signals which is smaller than the other. In details, if the driver's demanding torque is larger than the target engine torque supplied from the TCS controller, the target engine torque is selected. On the contrary, if the target engine torque is larger than the driver's demanding torque, the driver's demanding torque is selected. Hence, in a case where it is necessary to output a large engine torque than the driver's demanding torque as the result of the calculation for the driving force control, the select-low method cannot cope with this case.
Therefore, it becomes necessary to select the signal used in the engine controller in response to another signal (a driving force control request signal) supplied from the TCS controller, not through the select-low method described above, In details, such a control structure may be considered that when the TCS controller executes the driving force control, the driving force control request signal having a logical value of “1” is generated and when the TCS controller does not execute the driving force control, the driving force control request signal having the logical value of “0” is generated. Then, the engine controller selects the driver's demanding torque in accordance with the vehicular driver's demanding (accelerator manipulation) when the driving force control request signal is at the logical value of “0” and selects the target engine torque supplied from the TCS controller when the driving force control request signal is at the logical value of “1”.
If the above-described control structure is adopted, the selection of the signal within the engine controller can be controlled at the TCS controller side. Therefore, such as inconvenience as the case where the select-low method is adopted can be eliminated. However, since the receipt and transmission of the signal are carried out between the TCS controller and engine controller via harness, there is a possibility that the logical value of the driving force control request signal is reversed due to surrounding noises.
If the logical value of the driving force control request signal were reversed during the non-execution of the driving force, the engine controller would select the target engine torque supplied from the TCS controller and the driving force of the engine would be controlled according to the value set as the instantaneous target engine torque.
It is, hence, an object of the present invention to provide apparatus and method for controlling an engine driving force for a vehicle.
The above-described object can be achieved by providing a driving force controlling apparatus for a vehicle, comprising: a driver's demanding torque setting device that sets a torque that a vehicular driver is demanding: a slip condition detector to detect a slip condition of vehicular road wheels; a target engine torque setting device that sets a target engine torque in accordance with the slip condition; a driving force control execution determining section that determines whether the driving force control should be executed in accordance with the slip condition; and an engine output torque determining section that gives a determination of an output torque developed by an engine of the vehicle on the basis of the driver's demanding torque and the target engine torque, the engine output torque determining section determining the engine output torque in accordance with the driver's demanding torque when the driving force control execution determining section negates the determination that the driving force control should be executed.
The
Foley & Lardner
Nguyen Tan
Nissan Motor Co,. Ltd.
Tran Dalena
LandOfFree
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