Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-09-20
2001-11-20
Nguyen, Hoang (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S603000, C060S611000
Reexamination Certificate
active
06318083
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to technology for improving transient response characteristics of supercharged pressure in an engine equipped with a charger and a throttle valve of which opening degree is electronically controlled.
2. Related Art of the Invention
There has heretofore been proposed a device for controlling an intake air amount by an engine equipped with a throttle valve of which opening degree is electronically controlled as disclosed in, for example, Japanese Unexamined Patent Publication No. 62-110536.
According to this device, the throttle valve is controlled by calculating a target torque of the engine based upon an accelerator opening degree and an engine rotational speed, and calculating a target throttle valve opening degree based upon the above target torque and the engine rotational speed to obtain a target intake air amount.
In electronically controlling the throttle valve of the engine equipped with a charger for supercharging intake air, it is possible to adjust the target throttle valve opening degree for the target intake air amount corresponding to the supercharged pressure that is variably controlled depending upon the operation conditions, which, however, is not enough for quickly changing the intake air amount due to a delay in the change of the supercharged pressure during the transient period in which the supercharged pressure is changing depending upon a change in the operation conditions. Therefore, it is not possible to control the intake air amount to meet the requirement. In an engine in which the stratified charge combustion and the homogeneous combustion are changed over to each other depending upon the operation conditions, in particular, the supercharged pressure for producing the same torque differs depending upon the respective combustions, giving the occurrence of a torque difference at the time of changing over the combustion.
SUMMARY OF THE INVENTION
The present invention was accomplished by giving attention to the above problem inherent in the prior art, and its object is to suppress a delay in an intake air amount caused by a delay in the change of the supercharged pressure during the transient period to so control the intake air amount as to meet the requirement, by suitably controlling the opening degree of a throttle valve.
Another object of the invention is to improve response characteristics of acceleration/deceleration performance by controlling the intake air amount while suppressing the delay.
A further object of the invention is to suppress a torque difference that occurs when the stratified charge combustion and the homogeneous combustion are changed over to each other by controlling the intake air amount while suppressing the delay.
A still further object of the invention is to control the intake air amount in a software manner without adding any particular hardware.
A yet further object of the invention is to maintain a good accelerator operability for a driver even when the atmospheric pressure has decreased such as when the vehicle is traveling at a high altitude, relying upon a modified embodiment of the control system.
In order to accomplish the above-mentioned objects, the present invention is constituted such that, in an engine with a charger in which an intake passage is provided with a throttle valve which is electronically controlled to a target opening degree and the charger on the upstream side of the throttle valve, a target supercharged pressure of the charger is set, a supercharged pressure on the upstream side of the throttle valve is detected, the target supercharged pressure is corrected in a direction of eliminating a delay in the intake air amount based upon a difference between the target supercharged pressure that has been set and the real supercharged pressure that is detected, and a target opening degree of the throttle valve is set based on the corrected target supercharged pressure.
Then, the target supercharged pressure is corrected in a direction of eliminating a delay in the intake air amount that is caused by a delay in the change of the supercharged pressure corresponding to a difference between the target supercharged pressure and the real supercharged pressure, and the opening degree of the throttle valve is corrected based upon the corrected target supercharged pressure.
This suppresses a delay in the intake air amount for a delay in the change of the supercharged pressure during the transient period, and makes it possible to quickly obtain a target intake air amount and, hence, to obtain acceleration/deceleration performance maintaining good response.
Further, the target supercharged pressure may be corrected based upon a deviation or a ratio between the target supercharged pressure and the real supercharged pressure.
Then, the target supercharged pressure can be easily corrected in a direction of eliminating the delay in the intake air amount based upon the deviation or the ratio between the target supercharged pressure and the real supercharged pressure.
The correction of the target supercharged pressure may be stopped when the difference (for example, deviation) between the target supercharged pressure and the real supercharged pressure becomes equal to or smaller than a set value.
The real supercharged pressure fluctuates at all times even in a steady state due to pulsation caused by the turbine, the suction and the like. When the target supercharged pressure is corrected in response thereto, then, the throttle valve must be moved at all times, resulting in further deterioration of the durability of the throttle valve.
Durability deterioration of the throttle valve can be suppressed by stopping the correction of the target supercharged pressure when the difference becomes equal to or smaller than the set value.
Further, an estimated supercharged pressure may be calculated based upon a change in the real supercharged pressure, to correct the target supercharged pressure based upon a difference between the target supercharged pressure and the estimated supercharged pressure.
In the system that corrects the target supercharged pressure based on a deviation or a ratio between the target supercharged pressure and the real supercharged pressure, a deviation (steady deviation) occurs between the target supercharged pressure and the real supercharged pressure when the atmospheric pressure decreases such as when the vehicle is traveling at a high altitude, even though the supercharged pressure is in an equilibrium state. If the throttle valve opening degree is corrected by correcting the target supercharged pressure even for the above deviation, then, the range in which the throttle valve can be controlled by a driver becomes narrow (output reaches a maximum before the accelerator is opened to a maximum degree), which is not desirable from the standpoint of operation.
Therefore, a change in the supercharged pressure during the transient period under the standard atmospheric pressure condition is estimated by using a rate of change without using an absolute value of the real supercharged pressure, and the target supercharged pressure is corrected based on the difference between the estimated supercharged pressure and the target supercharged pressure to eliminate steady deviation so that a good operability can be maintained by inhibiting the correction of the throttle valve opening degree for the steady deviation (the control range for the driver can be maintained so that a maximum output is obtained at a maximum accelerator opening degree).
The correction of the target supercharged pressure may be stopped when the difference (for example, deviation) between the target supercharged pressure and the estimated supercharged pressure becomes equal to or smaller than a set value.
Because of the same reasons as those of when the target supercharged pressure and the real supercharged pressure were used, the correction of the target supercharged pressure is stopped when the deviation between the target supercharged pressure and the estimated s
Fuse Toru
Kawasaki Takao
Machida Kenichi
McDermott & Will & Emery
Nguyen Hoang
Unisia Jecs Corporation
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