Internal-combustion engines – Engine speed regulator – Responsive to deceleration mode
Reexamination Certificate
1999-06-18
2001-02-27
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Responsive to deceleration mode
C123S090110, C123S295000, C123S339170, C123S339180, C123S481000, C180S197000, C477S109000
Reexamination Certificate
active
06192857
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a control apparatus of an engine with electromagnetically driven intake and exhaust valves and more particularly, to an engine control apparatus with electromagnetically driven intake and exhaust valves which can provide a wide dynamic range of engine brake torque even during fuel cut by controlling the valve open timing of the electromagnetically driven exhaust valve.
A technique disclosed in, for example, JP-A-63-147957 has hitherto been known in which by changing the valve timing of an electromagnetically driven valve, the engine brake effect can be obtained and the torque shock and pumping loss can be decreased. More particularly, in the technique, the valve timing of the intake valve is set to normal timing during deceleration fuel cut and is switched to the early close timing immediately before the fuel cut ends, that is, fuel supply is resumed.
However, the valve switching timing described in the conventional technique as above is set to two stages of normal timing and early close timing and therefore, when the early close timing always proceeds during the fuel cut, the pumping loss is decreased excessively to raise a disadvantage that the engine brake effect becomes insufficient.
Then, a technique has been proposed in JP-A-9-88645, according to which the valve open timing of the intake valve is controlled more finely under a predetermined running condition for fuel cut, thereby decreasing the pumping loss and providing suitable engine brake.
SUMMARY OF THE INVENTION
In the aforementioned technique, the pumping loss can be decreased and suitable engine brake can be obtained by stopping the fuel supply to the engine and correcting the valve open time of the electromagnetically driven intake valve so as to decrease it when a predetermined deceleration condition of the engine is detected but the object to be controlled is the intake valve and the valve open time during intake stroke is controlled, raising a problem that the dynamic range of the engine brake torque cannot be widened.
Further, in a kind of engine system having no throttle valve, the pumping loss does not take place, raising a problem that the engine brake torque per se cannot be obtained.
The present invention contemplates elimination of the above problems and it is an object of the present invention to provide an in-cylinder injection engine control apparatus which can widen the dynamic range of engine brake torque.
To accomplish the above object, an engine control apparatus with electromagnetically driven intake and exhaust valves according to the invention comprises valve control means including fuel injection timed valve controlling means, fuel cut timed valve controlling means and means for controlling drive of intake and exhaust valves on the basis of output signals of the above two means, wherein the fuel cut timed valve controlling means includes exhaust valve open/close timing calculating means for making the valve open timing of the exhaust valve earlier than the fuel injection timing during fuel cut, and the valve control means includes fuel cut deciding means for determining fuel cut under at least one condition that the accelerator operating amount (accelerator pedal depression amount) is detected as being near zero and valve drive changing means for switching an output signal from the fuel injection timed valve controlling means to an output signal of the fuel cut timed valve controlling means when the fuel cut is determined.
In the engine control apparatus with electromagnetically driven intake and exhaust valves according to the invention constructed as above, when fuel is cut with the accelerator operating amount detected as being near zero, the valve open timing of the exhaust valve can be made to be earlier than the fuel injection timing and consequently, sufficient engine brake torque can be obtained.
Also, by controlling the valve open timing of the exhaust valve during the fuel cut to make it variable between the early stage of expansion stroke (near TDC) and the late stage thereof (near BDC), the magnitude of engine brake torque can be controlled and the variable range of the valve open timing can be widened, thereby widening the dynamic range of the engine brake torque.
Further, when large braking torque is required, the valve open timing of the exhaust valve is caused to approach the early stage of expansion stroke (near TDC) and when small braking torque is required, the valve open timing of the exhaust valve is caused to approach the late stage of expansion stroke (near BDC), thereby ensuring that the magnitude of engine brake torque can be controlled.
Furthermore, by gradually advancing the valve open timing of the exhaust valve during engine braking from the late stage of expansion stroke to the initial (early) stage thereof, a shock due to a rapid change of plus (firing) torque to minus (engine brake) torque caused at the time that the accelerator step-on state changes to the accelerator step-off state can be decreased.
In addition, when down shifting from the high speed side gear to the low speed side gear is effected during deceleration by means of AT (Automatic Transmission) control device, a shock during the down shifting can be decreased by changing stepwise the valve open timing of the exhaust valve from the initial or middle stage of expansion stroke to the late stage thereof concurrently with shifting to the low speed side gear and thereafter changing gradually the vale open timing of the exhaust valve from the late stage of expansion stroke to the middle or initial stage thereof to thereby increase the engine brake torque gradually and decrease a shock during down shifting.
Further, when one or more cylinders are made not work by fuel cut for traction control, by changing the valve open timing of the exhaust valve of the cylinder in which fuel cut proceeds to thereby change minus torque continuously, torque shock at a transient state of changing the number of cylinders of fuel-cut can be prevented and as a result, smooth traction control can be ensured.
Furthermore, by providing a re-triggerable delay timer which is turned on for a predetermined time when the slip rate of the wheel is larger than a threshold value during ABS control and which is restarted to be turned on for the predetermined time from a time point at which the slip rate of the wheel again exceeds the threshold value within the on-time, the engine brake torque can be decreased when the slip rate is high, causing the effect of ABS control to fulfil itself.
Besides, when the road surface condition is good with the slip rate decreased and the engine brake torque is allowed to be applied, sufficient braking force can be obtained regardless of actuation
on-actuation of the ABS.
Further, when basic fuel injection quantity Tp
1
, reference fuel injection quantity Tp
2
and target fuel injection quantity Tp
3
are determined and intake air flow Qa is feedback-controlled to cause the basic fuel injection quantity Tp
1
to follow the target fuel injection quantity Tp
3
, the valve open timing of the intake valve is calculated as an intermediate parameter to increase the response capability or speed of engine speed control.
At that time, the reference fuel injection quantity Tp
2
can be a variable retrieved through a map of engine speed axis and accelerator operating amount axis or the reference fuel injection quantity Tp
2
can be a variable retrieved through a table of accelerator operating amount axis.
The control parameter can include one or a plurality of parameters such as air-fuel ratio, ignition timing, fuel injection start timing, fuel injection end timing, EGR rate and magnitude of in-cylinder swirl.
Further, the control parameters may be maps retrievable in accordance with the engine speed axis and the reference fuel injection quantity Tp
2
axis and each map may include three sheets of maps for stoichiometry, homogeneous (weak) lean and stratified (strong) lean.
Furthermore, by increasing the reference fuel injection quantity Tp
2
when the
Argenbright Tony M.
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Hitachi , Ltd.
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