Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-05-31
2001-08-28
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S053000, C701S054000, C701S055000, C477S110000, C477S125000
Reexamination Certificate
active
06282481
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving force control apparatus for vehicles and a driving force control method for vehicles, which controls driving force transmitted to the wheels.
2. Related Background Art
An example of the conventionally known driving force control apparatus for vehicles is one constructed to detect an acceleration slip occurring at the driving wheel under acceleration of a vehicle and effect braking at the driving wheel upon occurrence of the acceleration slip, as described in Japanese Patent Application Laid-Open No. 8-61107. This apparatus is intended for such control that the power output of the internal combustion engine is restrained to effect braking at the driving wheel upon occurrence of the acceleration slip, so as to decrease a speed difference between the left and right driving wheels, thereby preventing seizure of the differential.
SUMMARY OF THE INVENTION
Since the conventional apparatus of this type is constructed to control the power output of the internal combustion engine simply when the rotational speed difference between the left and right driving wheels becomes over a predetermined value, there is the possibility that driving force of the internal combustion engine is over-restrained, so as to degrade driving performance of the vehicle, however. For example, when the vehicle runs on a road surface with large running resistance, such as a muddy road or a deep snow road, the road ability is often higher in the case of the vehicle running with maintaining the power output of the internal combustion engine as much as possible. Therefore, the excessive suppression of the driving force of the engine is not preferable in that case.
The present invention has been accomplished in order to solve this problem and an object of the present invention is to provide a driving force control apparatus for vehicles and a driving force control method for vehicles that can maintain the driving force during running while preventing a breakdown of the power train, thereby improving the driving performance.
Namely, a driving force control apparatus for vehicles according to the present invention is a driving force control apparatus for vehicles, which controls driving force distributed through a differential gear unit to a plurality of wheels, the driving force control apparatus comprising: permissible torque computing means for computing permissible torque that can be permitted to enter the differential gear unit, based on a differential rotational speed of the differential gear unit; input torque computing means for computing input torque entered into the differential gear unit; and control means for performing control to decrease engine power output so as to keep the input torque into the differential gear unit not more than the permissible torque when the input torque computed by the input torque computing means is greater than the permissible torque computed by the permissible torque computing means.
The driving force control apparatus for vehicles according to the present invention is also characterized in that the aforementioned control means performs the control to decrease the engine power output by adjusting a throttle opening angle of a throttle valve.
The driving force control apparatus for vehicles according to the present invention is also characterized by further comprising: target torque computing means for setting the permissible torque as target torque of the input torque when the input torque computed by the input torque computing means is greater than the permissible torque computed by the permissible torque computing means; and target throttle opening computing means for computing a target throttle opening angle, based on the target torque and an engine speed, and characterized in that the aforementioned control means performs the control to decrease the engine power output so as to keep the input torque into the differential gear unit not more than the permissible torque, by adjusting the throttle opening angle, based on the target throttle opening angle computed by the target throttle opening computing means.
The driving force control apparatus for vehicles according to the present invention is also characterized in that the permissible torque computing means, the input torque computing means and the control means are ECU.
A driving force control method for vehicles according to the present invention is a driving force control method for vehicles, which controls driving force distributed through a differential gear unit to a plurality of wheels, the driving force control method comprising the steps of: computing permissible torque that can be permitted to enter the differential gear unit, based on a differential rotational speed of the differential gear unit; computing input torque entered into the differential gear unit; and performing control to decrease engine power output so as to keep the input torque into the differential gear unit not more than the permissible torque when the input torque computed is greater than the permissible torque computed.
The driving force control method for vehicles according to the present invention is also characterized in that the steps of performing control to decrease engine power output includes performing the control to decrease the engine power output by adjusting a throttle opening angle of a throttle valve.
The driving force control method for vehicles according to the present invention is also characterized by further comprising the steps of: setting the permissible torque as target torque of the input torque when the input torque computed is greater than the permissible torque computed; and computing a target throttle opening angle, based on the target torque and an engine speed, wherein the step of performing control to decrease engine power output includes performing the control to decrease the engine power output so as to keep the input torque into the differential gear unit not more than the permissible torque, by adjusting the throttle opening angle, based on the target throttle opening angle computed.
According to the invention described above, the input torque entered into the differential gear unit is controlled at or below the given permissible value, whereby an overload can be prevented from being exerted on the differential gear unit. On the other hand, the driving force is not restrained when the input torque into the differential gear unit is not more than the given permissible value. When the input torque is greater than the given permissible value, the engine power output can be controlled so as to keep the input torque at the upper limit of the permissible value. Therefore, the constant driving force is maintained and the driving performance of the vehicle can be improved thereby.
The driving force control apparatus for vehicles according to the present invention is also characterized by further comprising traction control means whereby when a slip occurs in either of the wheels, braking force is exerted on the wheel to restrain the slip.
The driving force control method for vehicles according to the present invention is also characterized by further comprising the steps of: braking force is exerted on the wheel to restrain the slip when a slip occurs in either of the wheels.
According to the invention, the braking force is exerted on the slipping wheel, so as to decrease the differential rotational speed of the differential gear unit, whereby the durability of the differential gear unit is improved further.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by wa
Cuchlinski Jr. William A.
Marc-Coleman Marthe
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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