Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2002-06-26
2004-06-22
Vo, Hieu T. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S113000, C477S203000
Reexamination Certificate
active
06754579
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on Japanese Patent Application No. 2001-195204 filed on Jun. 27, 2001 the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an engine control system for a vehicle. The system has an idling stop and automatic restart feature.
2. Description of Related Art
JP-A-58-166165 discloses an engine control system that engages a lock-up clutch of a torque converter and stops fuel supply to the engine when the vehicle in a deceleration and vehicle speed is reduced gradually. As a result, the engine is kept in rotation by directly connecting a crankshaft of the engine and an automatic transmission. It is possible to improve fuel economy.
In this case, it is normal to prevent engine stall by releasing the lock-up clutch and restarting fuel supply when the engine speed is reduced to a predetermined value higher than an idling engine speed in a state of cutting fuel.
JP-A-8-189395 has proposed an engine automatic starting and stopping system for reducing an amount of fuel consumption more than the above-described conventional technology by carrying out a control of cutting fuel while bringing a clutch into a connected state during a time period of establishing an automatic stopping condition of an engine even in the case in which a fuel cut control condition is not established and automatically stopping the engine by releasing the clutch when a clutch releasing condition is established during the time period of establishing the automatic stopping condition of the engine.
According to the engine automatic starting and stopping system, the engine is automatically stopped in running and therefore, when there is used a brake apparatus for carrying out assistance with negative pressure of an intake pipe of the engine as a power source, operability of the brake is deteriorated in running when the engine is being stopped.
With respect to the problem, when there is used a way of thinking of JP-A-58-30438/1983, negative pressure of the brake apparatus can be ensured without operating an electric negative pressure pump by detecting booster negative pressure of the brake apparatus and ensuring the brake negative pressure by restarting the engine when the negative pressure becomes equal to or smaller than a predetermined value.
However, according to the method, there is a time lag in restarting the engine and therefore, there is a case in which booster negative pressure sufficient for operating the brake cannot be ensured in rapid braking operation while stopping the engine in running.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automatic engine stop and start system that is capable of supplying sufficient negative pressure for a brake device.
It is another object of the present invention to provide an automatic engine stop and start system that is capable of restarting the engine before negative pressure is decreased below a predetermined threshold.
According to an aspect of exemplary embodiment of the present invention, an automatic engine stop and start system has negative pressure detecting means for detecting a negative pressure for assisting a brake booster, braking operation detecting means for detecting a braking operation of a driver, and an engine controller for automatically stopping or starting the engine under establishment of a predetermined condition of the engine based on an input signal. The engine controller automatically starts the engine when it is determined that there is carried out a predetermined braking operation for bringing about, as a result, a situation in which the booster negative pressure is estimated to be smaller than a predetermined threshold based on the booster negative pressure and the braking operation.
That is, according to the constitution, the combination of the booster negative pressure and the braking operation is checked with previously stored memory information, it is determined whether the combination is accompanied by a concern of bringing about a reduction in the booster negative pressure effecting adverse influence on the braking operation and when there is the concern, the engine is restarted. Thereby, even when the booster negative pressure is provided with a value sufficiently withstanding a certain kind of the braking operation, in the case in which there is a possibility of effecting adverse influence on the braking operation by carrying out the predetermined braking operation (for example, rapid braking or high speed repeated braking), the engine is restarted and therefore, the engine can be restarted before the booster negative pressure is reduced as a result of the predetermined braking operation. As a result, without awaiting for delay time for restarting the engine, which is brought about when the engine is restarted by simply monitoring the booster negative pressure and when needed (when a reduction in the booster negative pressure needs to restart the engine), the engine can swiftly be restarted before the booster negative pressure is actually reduced and a deterioration in the braking operation can be prevented.
According to an aspect of exemplary embodiment of the present invention, a controller automatically start the engine when there is carried out an operation in which a brake depressing amount is equal to or larger than a predetermined value as the predetermined braking operation under a situation in which the booster negative pressure is equal to or smaller than a predetermined value. That is, under the situation in which the booster negative pressure is reduced to some degree, the engine is restarted with respect to the brake depressing operation having a deep depression significantly reducing the booster negative pressure. Therefore, even when the brake depressing amount is increased, a drawback by delay in restarting the engine can be resolved.
The controller may automatically start the engine when there is carried out an operation in which a rate of changing a brake depressing amount is equal to or larger than a predetermined value as the predetermined braking operation under a situation in which the booster negative pressure is equal to or smaller than a predetermined value. Thereby, there can be resolved occurrence of a failure in assisting the braking operation caused by braking operation for bringing about a rapid reduction in the booster negative pressure such as rapid braking or pumping braking significantly consuming the booster negative pressure under a state in which the booster negative pressure is proximate to an engine restarting limit.
The controller may automatically start the engine when there is carried out an operation in which an accumulated change amount of a brake depressing amount during an immediately proximate predetermined time period is equal to or larger than a predetermined value as the predetermined braking operation under a situation in which the booster negative pressure is equal to or smaller than a predetermined value.
That is, the accumulated amount is brought into a close positive correlated relationship with an amount of reducing the booster negative pressure and therefore, when the accumulated change amount of the brake depressing amount significantly consuming the booster negative pressure is large in the state in which the booster negative pressure is proximate to the engine restarting limit, by restarting the engine with respect to the braking operation, swift engine restarting can be realized and a drawback caused by a delay in restarting the engine can be resolved.
The controller may estimate the booster negative pressure when the brake depressing amount is made to be smaller than a current value thereof by a predetermined amount from the current booster negative pressure and the current brake depressing amount. The controller may start the engine when the estimated booster negative pressure is smaller than the predetermined threshold.
That is, according to the constitution, in the pumping operation
Kamiya Masaru
Kato Akira
Tanaka Naoki
Denso Corporation
Vo Hieu T.
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