Variable valve timing engine

Details Variable valve timing engine Variable valve timing engine

1999-09-07

2001-02-20

Denion, Thomas (Department: 3748)

Internal-combustion engines

Charge forming device

Fuel injection system

C123S090150, C073S118040

Reexamination Certificate

active

06189512

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to improvements in a variable valve timing engine which is provided with intake valves whose valve timings are freely controllable so as to regulate an intake air quantity, and more particularly to a system for estimating the intake air quantity when a trouble arises in an intake air quantity measuring device in the variable valve timing engine.
A variable valve timing engine whose valve timings are freely controllable to regulate an intake air quantity has been proposed as disclosed in Japanese Patent Provisional Publication No. 10-37727. This variable valve timing engine is provided in its intake air passageway with an intake air quantity measuring device such as an airflow meter.
SUMMARY OF THE INVENTION
In such a variable valve timing engine, an intake air quantity measured by an intake air quantity measuring device such as an airflow meter is important for operation of the engine, i.e., for decision of a fuel injection quantity and the like. In the event that a trouble arises in the intake air quantity measuring device, the intake air quantity cannot be measured thereby seriously affecting operation of the engine.
In a usual engine, control for the intake air quantity is accomplished by a throttle valve. Accordingly, when a trouble arises in the intake air quantity measuring device, the intake air quantity can be estimated from the opening degree of the throttle valve (or opening area of the intake air passageway) for the backup purpose, thereby solving the above problems.
However, in the conventional variable valve timing engine of the type for controlling the intake air quantity by varying the valve timings of the intake valves, in general, no throttle valve is provided, or otherwise a throttle valve is provided only for the purpose of developing vacuum in the intake air passageway. As a result, it is impossible to estimate the intake air quantity from the opening degree of the throttle valve when a trouble arises in the intake air quantity measuring device. Thus, the conventional variable valve timing engine cannot solve the above problems.
In view of the above, it is an object of the present invention to provide an improved variable valve timing engine of the type wherein an intake air quantity is controllable by regulating valve timings of an intake valve, which can effectively overcome drawbacks encountered in conventional variable valve timing engines of the similar types.
Another object of the present invention is to provide an improved variable valve timing engine of the type wherein an intake air quantity is controllable by regulating valve timings of an intake valve, which engine is provided with an intake air quantity estimating system which can accurately estimate the intake air quantity in the event that a trouble arises in an intake air quantity measuring device such as an airflow meter.
A further object of the present invention is to provide an improved variable valve timing engine of the type wherein an intake air quantity is controllable by regulating valve timings of an intake valve, which engine is provided with an intake air quantity estimating system by which the intake air quantity can be accurately estimated in accordance with valve timings of the intake valve.
An aspect of the present invention resides in a variable valve timing engine which comprises an intake valve whose valve timing is variable to control a quantity of intake air to be supplied to a cylinder. An intake air quantity measuring device is provided for measuring the intake air quantity. An intake air quantity estimating system is provided including a control unit which is programmed to carry out (a) judging that a trouble arises in the intake air quantity measuring device, so as to provide a judgment result, and (b) calculating the intake air quantity in accordance with the valve timing of the intake valve, upon providing the judgment result.
Another aspect of the present invention resides in a method of operating a variable valve timing engine having an intake valve whose valve timing is variable to control an quantity of intake air to be supplied to a cylinder, and an intake air quantity measuring device for measuring the intake air quantity. The operating method comprises an intake air quantity estimating process which includes (a) judging that a trouble arises in the intake air quantity measuring device, so as to provide a judgment result; and (b) calculating the intake air quantity in accordance with the valve timing of the intake valve, upon providing the judgment result.


REFERENCES:
patent: 4945883 (1990-08-01), Ono et al.
patent: 5115782 (1992-05-01), Klinke et al.
patent: 5190012 (1993-03-01), Takahashi
patent: 5560199 (1996-10-01), Agustin
patent: 39 40 752 (1991-06-01), None
patent: 42 36 008 (1994-04-01), None
patent: 195 47 496 (1997-07-01), None
patent: 10-37727 (1998-02-01), None

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