Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-01-24
2001-11-20
Denion, Thomas (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S600000, C060S602000, C060S612000, C123S337000
Reexamination Certificate
active
06318085
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for controlling a coasting air recirculation valve of the turbocharger of an internal combustion engine, the coasting air recirculation valve being arranged in a coasting air recirculation line that bypasses a compressor in the intake duct, and the coasting air recirculation valve being controllable by way of the intake duct pressure on the downstream side of the throttle valve.
BACKGROUND INFORMATION
A conventional apparatus is described in German Patent No. 28 23 067. In this German Patent, the coasting air recirculation valve is activated exclusively pneumatically by the intake duct pressure: the coasting air recirculation valve opens when a certain negative pressure, occurring while the vehicle is in coasting mode, is present in the intake duct on the outflow side of the throttle valve. The fact that the outlet of the compressor is connected to its inlet via the coasting air recirculation line causes a decrease in the boost pressure in the intake duct downstream from the compressor, which is expressed as better engine response to rapid closing of the throttle valve. The opening or closing behavior of the coasting air recirculation valve is not optimally defined in the case of activation exclusively by way of the intake duct pressure.
U.S. Pat. No. 5,083,543 describes a coasting air recirculation valve which has its control pressure delivered from a negative pressure vessel. This negative pressure vessel is fed from the intake duct pressure. The coasting air recirculation valve is thus controlled solely as a function of the intake duct pressure.
Japanese Patent Application No. 06 117 263 (provided in, e.g., Patent Abstracts of Japan, Vol. No. 408, Jul. 29, 1994) describes a coasting air recirculation valve which is controlled as a function of the negative pressure in the intake duct on the downstream side of the throttle valve, and which is located in a coasting air recirculation line. Inserted in a line between the intake duct downstream side and the coasting air recirculation valve is a vacuum vessel whose negative pressure depends solely on the negative pressure in the intake duct on the downstream side of the throttle valve. The purpose of the vacuum vessel is to damp air flow noises that occur when the coasting air recirculation valve is opened.
It is therefore the object of the present invention to describe an apparatus of the kind cited initially that allows highly defined opening and closing of the coasting air recirculation valve.
SUMMARY OF THE INVENTION
This object is achieved with an electrically controllable solenoid valve according to the present invention, which delivers to the coasting air recirculation valve (as a function of a control signal) either the intake duct pressure or a control pressure, independent thereof, from a negative pressure vessel. Thus, it is possible to prevent the coasting air recirculation valve from being prematurely closed by the negative intake duct pressure on the downstream side of the throttle valve in the event of rapid closure of the throttle valve due to pumping of the boost air column. The boost pressure is uniformly and continuously decreased. Boost pressure fluctuations, and jerking of the vehicle caused thereby, are prevented.
It is advantageous for a control signal activating the solenoid valve to be emitted if the load gradient of the engine exceeds a threshold that depends on reference boost pressure. The load gradient can have a predictive value superimposed on it if the current load gradient has risen as compared with the load gradient existing one timing cycle earlier.
It is advantageous for a control signal activating the solenoid valve to be made available if the absolute intake duct pressure lies below a pressure threshold at which the coasting air recirculation valve would open. A control signal activating the solenoid valve should then be made available if the absolute intake duct pressure exceeds the pressure threshold. The pressure threshold can be taken from a characteristics diagram that depends on the actual boost pressure and the ambient pressure.
REFERENCES:
patent: 4282713 (1981-08-01), Antoku et al.
patent: 4434775 (1984-03-01), Yoshimura et al.
patent: 5083543 (1992-01-01), Harada et al.
patent: 5103791 (1992-04-01), Tomisawa
patent: 5201790 (1993-04-01), Mukai et al.
patent: 6018949 (2000-02-01), Brosecke et al.
patent: 28 23 067 (1978-12-01), None
patent: 196 39 146 (1997-11-01), None
patent: 06 117263 (1994-04-01), None
Bauerle Michael
Franke Steffen
Haming Werner
Kluth Carsten
Surjadi Iwan
Denion Thomas
Kenyon & Kenyon
Robert & Bosch GmbH
Trieu Thai-Ba
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