Internal-combustion engines – Engine speed regulator – Idle speed control
Patent
1997-02-12
1998-01-27
Nelli, Raymond A.
Internal-combustion engines
Engine speed regulator
Idle speed control
F02M 300
Patent
active
057112711
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a throttle apparatus for an internal combustion engine. A throttle apparatus is already known (MTZ, Motortechnische Zeitschrift 54 (1993), No. 11, p. 601), which is embodied as a preassembled unit. The throttle apparatus has a throttle device in the form of a throttle valve, which is rotatably accommodated in a throttle valve support. The throttle apparatus also has a bypass conduit, whose cross section is variable by an idling adjuster for the sake of idling regulation. Upstream of the throttle valve, a temperature sensor is also provided, which measures the temperature of the air flowing in the throttle valve support. The throttle apparatus is mounted on an air distributor, which is provided in the region of a cylinder head of the engine, in order to distribute the air, metered by the throttle valve, via individual intake tubes to individual combustion chambers of the engine. A pressure sensor, which measures the air pressure in the air distributor, is accommodated in the air distributor.
Modern engine control systems require a great deal of information about important operating variables of the engine; the information is furnished by sensors and delivered in the form of electrical signals to an electronic control unit for evaluation. From the sensor signals, the electronic control unit calculates corresponding trigger signals for the final control elements of the engine controller, such as for ignition or for mixture preparation. One important variable is the air mass aspirated by the engine. It is known to ascertain the air mass for instance from the rotary position of the throttle valve and the associated engine rpm. However, that method is relatively inaccurate, and hence air flow rate meters are used, which determine the air mass or flow rate in the throttle valve support upstream of the throttle valve by means of a heated, temperature-dependent measuring element in the form of a hot wire or hot film. Such air flow rate meters are relatively expensive, however.
A further possibility for determining the air mass aspirated by the engine with relatively high accuracy is to ascertain the air mass indirectly from the density of the air in the throttle valve support and from the associated displacement volume of the individual pistons of the engine. The density of the aspirated air can be calculated from the status variables of temperature and pressure of the air; to that end, in the prior art referred to at the outset, a temperature sensor and a pressure sensor are provided. However, in the engine idling range, a relatively low flow speed prevails in the throttle valve support, and thus the aspirated air stays for a relatively long time in the throttle valve support and in the air distributor that for instance is appended to it. The air can then heat up on the warm walls of the throttle valve support and the air distributor, which raises the temperature of the air and changes the air mass, yet the temperature sensor and pressure sensor detect this only with some delay, so that particularly in the critical idling phase of the engine, measurement inaccuracies can occur.
Besides detecting the air mass aspirated by the engine, an engine control system also takes on the task of controlling a regeneration valve, which is part of a fuel vapor trapping system in a fuel tank of the engine. In this kind of fuel vapor trapping system, the fuel vapors in the tank are first temporarily stored in an adsorption filter and then, at certain operating states of the engine, are fed by means of the regeneration valve into the throttle valve support. For that purpose, the engine control system requires among other things information about the current rotary position of the throttle valve, and a rotational angle encoder, for instance in the form of a precision potentiometer, is therefore provided on a shaft of the throttle valve.
The electronic control unit, the regeneration valve, the idling adjuster, the temperature sensor, and the pressure sensor have until now been accommodated in indi
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Jauernig Peter
Laue Harald
Litzinger Rolf
Rottler Jurgen
Schellenberg Gerhard
Greigg Edwin E.
Greigg Ronald E.
Nelli Raymond A.
Robert & Bosch GmbH
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