Fluid handling – With indicator – register – recorder – alarm or inspection means – Fluid pressure responsive indicator – recorder or alarm
Patent
1999-07-15
2000-12-26
Lee, Kevin
Fluid handling
With indicator, register, recorder, alarm or inspection means
Fluid pressure responsive indicator, recorder or alarm
73299, 123509, 123514, G01F 2318
Patent
active
061643254
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is based on a level measuring device for a fuel tank of a motor vehicle.
A level measuring device of this kind is known from DE 39 14 637 A1. This level measuring device has a measuring tube disposed in the fuel tank, which extends from the bottom of the fuel tank to at least the height of the maximal fill level of the fuel tank and into which the fuel is delivered. The level measuring device also has a differential pressure sensor, whose one measurement input is connected to the lower end of the measuring tube and whose other measurement input is subjected to the fluid pressure at the bottom of the fuel tank. The measuring tube has an overflow opening which is disposed at least at the height of the maximal fill level of the fuel tank. The measuring tube can be emptied by means of an opening disposed close to the bottom of the fuel tank or by means of a valve at the height of the current level of the fuel tank. The level determination takes place in an evaluation device based on the difference of the output signals of the differential pressure sensor when the measuring tube is filled up to the overflow opening and when the measuring tube is emptied to the current level of the fuel tank. The delivery of fuel into the measuring tube takes place by way of a return line, through which fuel not consumed by the internal combustion engine of the motor vehicle is delivered back into the fuel tank. The fuel flowing through the return line is possibly heated so that there is a temperature difference between the fuel in the measuring tube and the fuel in the fuel tank, which in turn results in a difference in the density of the fuel in the measuring tube in comparison to the density of the fuel in the fuel tank, which leads to errors in the output signals of the differential pressure sensor. Furthermore, fuel delivery systems are also known in which there is no return from the engine to the fuel tank so that the known level measuring device cannot be used.
SUMMARY OF THE INVENTION
In accordance with the present invention, the delivery unit is disposed in the fuel tank and delivers fuel from the fuel tank to an injection system of an internal combustion engine of the motor vehicle, and the measuring tube of the level measuring device is filled by means of a partial flow of the fuel delivered by the delivery unit.
The level measuring device according to the invention, which is for a fuel tank of a motor vehicle, has the advantage over the prior art in that the fuel delivered into the measuring tube is not heated and that it is possible to use it in fuel delivery systems without a return.
BRIEF DESCRIPTION OF THE DRAWINGS
Two exemplary embodiment of the level measuring device according to the invention are depicted in the drawings and are explained in more detail in the description below.
FIG. 1 shows a fuel tank of a motor vehicle with a level measuring device according to a first exemplary embodiment disposed in it, with a filled measuring tube,
FIG. 2 shows the fuel tank with the level measuring device with an empty measuring tube, and
FIG. 3 shows the fuel tank with the level measuring device according to a second exemplary embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1 to 3 respectively show a fuel tank 10 of a motor vehicle, which can be comprised of metal or plastic. A level measuring device 12 is disposed in the fuel tank 10, which is used to detect the level of the fuel tank 10, which is depicted in a known manner on a indicator instrument 34 in the vehicle driver's field of view. The level measuring device 12 has a vertically extending measuring tube 14 which is disposed in the fuel tank 10 and whose cross section is significantly smaller than the cross section of the fuel tank 10. The measuring tube 14 can, for example, be comprised of plastic or metal and extends from the bottom 16 of the fuel tank 10 to the vicinity of its top 18. Close to its upper end 20, the measuring tube 14 has an overflow opening 22, which feeds into the fuel tank 10.
T
REFERENCES:
patent: 4554830 (1985-11-01), Khoi
patent: 4928657 (1990-05-01), Asselin
patent: 5265644 (1993-11-01), Tuckey
patent: 5661228 (1997-08-01), Young
patent: 6065335 (2000-05-01), Denz et al.
Lee Kevin
Robert & Bosch GmbH
Striker Michael J.
LandOfFree
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