Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1999-02-18
2001-07-31
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S085000, C701S068000, C477S906000
Reexamination Certificate
active
06269294
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to drive control devices provided for vehicles having automatic transmission for changing gears in response to shift ranges.
2. Description of the Related Art
Generally, vehicles (e.g. cars) are equipped with automatic transmission for changing gears in response to shift ranges such as the non-running range and running range, each of which is appropriately selected by a driver. At a shift mode to change gears from the non-running range to the running range, a driver of the vehicle inevitably feels a start shock in running.
The vehicle equipped with the automatic transmission, which is disclosed by the paper of Japanese Patent Application, Publication No. Hei 5-118435, for example, operates as follows:
At a start mode, the shift range is changed from the neutral range (i.e., N range) to the drive range (i.e., D range). Therefore, oil pressure is applied to the clutch of the gear which is selectively engaged at the start mode, so that the clutch is put in an engaged state. Thus, drive force of the engine is transmitted to the wheels via the engaged gear at the start mode. Normally, the driver depresses the accel (or accelerator pedal) to start the vehicle after changing the gears from the N range to the D range.
In some case, there occurs a situation due to carelessness of the driver that the driver depresses the accelerator pedal in the N range but the drive changes gears from the N range to the D range while depressing the accelerator pedal. For instance, such a situation occurs as follows.
The driver does not take notice of a fact that the shift range is presently placed in the N range but watches another vehicle, parked in front of the driver's vehicle, to suddenly start running. In that case, the driver depresses the accelerator pedal in a fluster, then, the driver realizes that the present shift range is the N range, so that the driver changes over the shift range from the N range to the D range.
In the aforementioned situation, engagement of the clutch is made under a condition that the engine speed is high. So, there occurs a problem that an engagement shock becomes large. The technology disclosed in the aforementioned paper suffers from such a problem as well.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a drive control device which is capable of easing an engagement shock of a clutch of a vehicle when a driver changes gears from the N range to the D range.
A drive control device of this invention is provided for a vehicle which has an automatic transmission and which is capable of setting a throttle opening independently of an accelerator opening. Herein, the drive control device detects a shift range selected by the automatic transmission and an engine speed, based on which prescribed controls are made with regard to a throttle and a clutch.
Namely, if the engine speed is higher than a predetermined engine speed value when the shift range is changed over from a non-running range (e.g., N range) to a running range (e.g., D range), the drive control device controls the throttle opening substantially in a fully closed state, regardless of the accelerator opening, while it also controls clutch oil pressure of a start-mode-engaged gear to be set at a predetermined oil pressure value which is greater than zero and at which the clutch does not have a torque transmission capacity.
The drive control device waits for an event that the engine speed is sufficiently reduced, then, the drive control device increases the clutch oil pressure to control the clutch in an engaged state. Therefore, it is possible to avoid a progression in engagement of the clutch under the condition where the engine speed is high, so it is possible to avoid occurrence of an engagement shock of the clutch.
Concretely speaking, for example, if the driver depresses the accelerator pedal in the N range but changes gears from the N range to the D range while depressing the accelerator pedal, the drive control device makes a control in such a way that the engine speed is reduced, regardless of depression of the accelerator pedal. Then, when the engine speed is reduced to some extent, the drive control device starts an engagement operation of the clutch. For this reason, engagement of the clutch is performed under the condition where the engine speed is low, so it is possible to ease the engagement shock of the clutch.
Besides, in a predetermined time after the engine speed becomes lower than the predetermined engine speed value, the drive control device maintains the throttle opening in the fully closed state while gradually increasing the clutch oil pressure of the start-mode-engaged gear so as to control the clutch to start an engagement operation.
In other words, at the timing when the throttle opening is place in the fully closed state so that the engine speed becomes lower than the predetermined engine speed value, the driver control device gradually increases the clutch oil pressure of the start-mode-engaged gear so that the clutch performs the engagement operation. In the predetermined time counted from the above timing, the drive control device maintains the throttle opening in the fully closed state, so that the engine speed is sufficiently reduced. Such controls are required to avoid occurrence of control hunting, which is caused to occur as follows.
If the clutch oil pressure is increased while the throttle opening is simultaneously restored to the original value (i.e., normal value corresponding to the accelerator opening) under the condition that the engine speed is not sufficiently reduced, the engine speed increases before the clutch has a torque transmission capacity, which causes occurrence of hunting on control of the vehicle.
Incidentally, as the aforementioned predetermined time, it is possible to set a time that brings the clutch to have the torque transmission capacity or so.
REFERENCES:
patent: 3733932 (1973-05-01), Uozumi et al.
patent: 4942784 (1990-07-01), Okahara
patent: 5113721 (1992-05-01), Polly
patent: 5957808 (1999-09-01), Iizuka
patent: 5-118435 (1993-05-01), None
Kon Takanori
Saito Yoshiharu
Armstrong Westerman Hattori McLeland & Naughton LLP
Cuchlinski Jr. William A.
Honda Giken Kogyo Kabushiki Kaisha
Pipala Edward
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