Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-07-24
2001-07-03
Nguyen, Hoang (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S612000, C060S615000
Reexamination Certificate
active
06253551
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an arrangement for controlling the boost pressure of an internal combustion engine which has a turbocharger in its at least one exhaust line and an actuator that acts on the turbocharger and is controlled by a first. The first controller is only switched through to the actuator when a fault detection device detects no fault in the operation of the engine.
BACKGROUND OF THE INVENTION
In boost pressure control, it may occur that a fault in the operation of the internal combustion engine (e.g., a combustion miss) or faulty sensors (e.g., air pressure sensor, air mass flow sensor) causes the speed of the turbocharger to be adjusted upward into a critical range and the turbocharger is permanently damaged as a result. German Patent No. 195 13 156 describes that this problem occurs, in particular, in internal combustion engines having two rows of cylinders with one turbocharger each. If one of the two turbochargers is in fact defective or a catalytic converter is clogged in one of the two exhaust lines, the control circuit will balance the system deviation of the actual boost pressure value from the setpoint boost pressure value caused by the fault occurring on one side by increasing the speed of the turbocharger on the side without a fault. In doing so, the speed of the turbocharger can reach a critical value, resulting in permanent damage to the turbocharger. In order to preclude permanent damage to a turbocharger in the event of a fault, as described in German Patent No. 195 13 156, the closed-loop control is switched off and a switchover is made to an open-loop control if a fault recognition device detects a fault in one side of the two exhaust gas lines. The open-loop control is designed in such a way that the speed of the turbocharger is not increased into its critical speed range. In contrast to closed-loop control, the actual value of charge air or air mass no longer has an influence on the control signal for the turbocharger in the event of a fault in open-loop control. The open-loop control limits the speed of the turbocharger to a constant value. In many types of faults, this value represents an overreaction in limiting the speed of the turbocharger to a constant value.
A control device for an internal combustion engine is described in U.S. Pat. No. 5,497,751, which provides two controllers for the control of the ignition and/or fuel injection for the individual cylinders. The identical input variables, which are provided by separate sensors, are supplied to both controllers so that both controllers make the same control information available to the ignition and/or injection device of the internal combustion engine. The control device therefore has a second controller in order to increase the reliability in an engine used in an airplane.
The objective of the present invention is to provide an arrangement that reacts with flexible control of the turbocharger in the event of a fault.
SUMMARY OF THE INVENTION
The object is attained in that a first controller which controls the turbocharger when no fault exists is switched off and a switchover is made to a second controller when a fault is detected in the operation of the engine. In this connection, the second controller receives a system deviation as an input signal that is different from the one received by the first controller boost pressure measured by an air pressure sensor in the intake path on the pressure side of the turbocharger serves as an actual value for the first system deviation and an air mass measured in the intake path on the suction side of the turbocharger serves as an actual value for the second system deviation. With such an arrangement, the control of the turbocharger can be adapted in an essentially more flexible manner to the type of the fault present than with a rigid control of the turbocharger.
A control signal suitable for the turbocharger in the case of a fault is produced by superimposing a precontrol signal on the output signal of the second controller. It is advantageous to make the precontrol signal dependent on the type of fault.
The fault recognition device should be capable of recognizing a great variety of signals. For example, it monitors the sensors required for the boost pressure control and/or an existing lambda control for errors and/or it detects combustion misses and signals a fault if a specific miss rate is exceeded.
In an internal combustion engine having two rows of cylinders with two turbochargers, both turbochargers are controlled simultaneously, a switchover taking place from the first to the second controller if the fault detection device detects a fault in the area of one of the two rows of cylinders.
REFERENCES:
patent: 4466248 (1984-08-01), Nartowski
patent: 4660382 (1987-04-01), Ueno et al.
patent: 4748567 (1988-05-01), Sumizawa et al.
patent: 4891946 (1990-01-01), Inoue
patent: 5497751 (1996-03-01), Yukio
patent: 40 32 451 (1992-04-01), None
patent: 195 13 156 (1996-05-01), None
Baeuerle Michael
Lohmann Andrea
Ries-Mueller Klaus
Kenyon & Kenyon
Nguyen Hoang
Robert & Bosch GmbH
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