Measuring and testing – Liquid level or depth gauge – With other measuring device
Patent
1993-08-12
1995-01-10
Gutierrez, Diego F. F.
Measuring and testing
Liquid level or depth gauge
With other measuring device
73299, G01F 2300, G01F 2314
Patent
active
053796381
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method and a device for detecting the fluid level of fuel in the tank of a motor vehicle.
Every motor vehicle with an internal combustion engine has a tank fluid-level sensor which is usually a device which checks the level of a float in the fuel tank and outputs a signal dependent on the level of the float.
A large number of motor vehicles have control devices in which operating parameter signals are subjected to digital data processing. For this purpose, the sensors whose signals are to be processed must be fed to the control device via lines and most of these signals must be digitized since they are initially present as analog signals. Because of the expenditure which is associated with the routing of the lines and the digitization, efforts are made to use as few signals as possible. The signal of the fluid-level sensor is one which typically is not processed in a control device. However, for various purposes, for example in conjunction with functions carried out in a tank venting system, it would be useful to know roughly the tank fluid-level.
If a signal relating to an operating parameter of interest is not fed to a control device, efforts are made to estimate the instantaneous value of the operating parameter which is of interest as satisfactorily as possible from values of other operating parameters concerning which the control device receives signals. In the present case, these can only be signals which originate from the tank and/or the tank venting system connected to it.
In vehicles with a tank venting system it is obligatory to check the operability of the said system to function, i.e. to investigate whether the system is leaktight and not clogged. In accordance with a catalogue of proposed requirements from the Californian Environmental Authority (CARB) published in 1989, testing is to take place in that lean correction testing is carried out with the aid of a lambda controller when certain conditions which make vaporization of the fuel very likely are fulfilled. If, in fact, a lean correction is required, it is assumed that fuel vapour has passed correctly through the tank venting system into the intake line of the motor vehicle so that the system is assessed to be leaktight and not clogged.
U.S. Pat. No. 4,962,744 discloses a method which utilizes a temperature sensor arranged in the adsorption filter of
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method and device for detecting a fluid level in a tank, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a changes such as occur during adsorption and desorption of fuel during a tank-filling process or during subsequent regeneration in an adsorption filter. The detected temperature changes are compared with predetermined values in order thus to determine whether the system is leaktight and not clogged.
DE-A-40,03,751 discloses a tank venting system which has a tank with tank pressure sensor, an adsorption filter which is connected to the tank via a tank connecting line and has a venting line which can be closed by means of a shut-off valve, and a tank venting valve which is connected to the adsorption filter via a valve line. In order to determine operability to function, the tank venting system thus constructed is operated in such a way that the shut-off valve is closed and then the system is pumped out via the tank venting valve with the aid of the partial vacuum in the intake line. If a predetermined partial vacuum is not achieved, the system is assessed as functionally defective.
In DE-A-41,11,361 which is part of a prior application but does not constitute a prior publication, a method for checking the leaktightness of a tank venting system is described which does not operate with the abovementioned pressure comparison but rather with pressure gradient comparisons. For this purpos
REFERENCES:
patent: 4949070 (1990-08-01), Wetzel
patent: 5090242 (1992-03-01), Hilton
patent: 5146783 (1992-09-01), Jansche et al.
Blumenstock Andreas
Denz Helmut
Gutierrez Diego F. F.
Robert & Bosch GmbH
Striker Michael J.
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