Fluid handling – With indicator – register – recorder – alarm or inspection means – Liquid level responsive indicator – recorder or alarm
Reexamination Certificate
2000-04-20
2001-07-24
Chambers, A. Michael (Department: 3753)
Fluid handling
With indicator, register, recorder, alarm or inspection means
Liquid level responsive indicator, recorder or alarm
C137S392000, C137S574000, C137S576000
Reexamination Certificate
active
06263916
ABSTRACT:
BACKGROUND
1. Field of the Invention
The invention relates to a tank system, in particular a fuel tank system having a splash pot and a filling level sensor, and to a method for controlling and operating such a tank system.
2. Related Art
It has already been proposed, for example, in German Application no. 196 10 154.9) to provide, within the main tank of a motor vehicle, an additional or reserve volume which is always filled up as a priority and which is automatically released by means of a switchable valve, as required (lowering of the filling level of the main tank below a predetermined minimum value). In order to improve the driver's information on the fuel supply available, simultaneously with the release of the reserve a signal indicating this operation and/or an accurately indicating or high-definition addition indication of the residual fuel quantity is activated. The vehicle driver can consequently estimate the remaining range of his vehicle more accurately. Use is made, in this case, of the fact that the geometry of the additional volume is simpler than that of present-day main tanks, since, with a view to optimum space utilization, these sometimes have a highly angular shape and therefore make it difficult to detect and indicate the filling level accurately.
The reserve supply is released into the main tank or into a splash pot, preferably directly on the suction side of the fuel pump. The additional volume is filled preferably directly from the inflow pipe (also tank filler neck).
It is normally located directly above the tank bottom and is always kept full. For refilling during operation, for example, suction jet pumps are used, which are operated by forward or return fuel streams and convey a volume flow constantly out of the main tank into the splash pot. There are also solutions with two-stage fuel pumps, the first stage of which feeds out of the main tank into the splash pot and the second stage of which then delivers from the splash pot to the carburetor or injection pump.
Excess quantities run over the upper edge of the splash pot back into the main tank. Suitable means (splash pot plates, labyrinth systems) prevent the splash pot from being emptied unintentionally, even when the vehicle undergoes high accelerations or decelerations. In the known system, admittedly, the changeover of the reserve release valve is controlled by a filling level limit switch arranged in the splash pot itself. Although it must be assumed that the splash pot will always be full if there is a sufficient supply of fuel in the main tank, in this configuration the possibility cannot be ruled out that, in the event of a merely temporary lack of fuel in the splash pot, the reserve volume is released prematurely and is then used up by the time the next refueling occurs.
Furthermore, a measuring device for tanks in motor vehicles is known, which possesses a main sensor arranged in a main tank and a secondary sensor for the filling level arranged in a secondary tank, as described in German Patent no. 32 24 919 A1). The volume present in the secondary tank serves as a reserve and is indicated. However, the indicated reserve is dependent on a filling level signal from the main sensor in the main tank. Since only the one measuring point is present in the main tank, the main sensor delivers signals which, depending on driving situations, are different from the actual filling level. The reserve indicator therefore also gives situations which differ from the actual filling level.
SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS
The object on which the invention is based is to improve even further the fuel tank system initially described and to specify an improved method for controlling and operating a tank system.
Regarding the device features, this object is achieved, according to the invention, by means of a fuel tank system having a tank with at least one filling level transmitter and a display for indicating the filling level of the tank; a measurable and indicatable reserve volume which is arranged in the tank and is always refuelable as a priority via an inflow pipe, and the content of which is available as a fuel reserve when a minimum filling level is reached in the main tank; a switching means for activating, by means of a control unit, an indicator signaling operation on fuel reserve; a splash pot which is arranged in the main tank and the content of which is capable of being sucked in by a fuel pump; the content of the splash pot being the measurable and indicatable reserve volume; wherein, in addition to the filling level transmitter, at least one further level transmitter for detecting a lack of fuel, said level transmitter being connected to the control unit, is provided in the tank near the bottom. The tank system is appreciably simplified and therefore becomes less complicated if the content of the splash pot is utilized directly as the reserve volume.
It is then possible not only to omit the separate additional volume, but also to dispense with the controlled release of the reserve volume by the switching of a valve. It goes without saying that the splash pot must be designed with a sufficient volume content, in order to ensure a minimum range during operation on fuel reserve.
A further advantageous effect of this arrangement is that, when new vehicles are filled for the first time, generally only a small fuel volume has to be introduced, but the ultimate purchaser is not left in doubt as to the potential remaining range of the new vehicle on account of the improved indication.
The tank system is automatically controlled and operated as follows: in the event of a lack of fuel in the main tank, a preferentially filled reserve volume is released automatically to the fuel pump fed from the splash pot; and the changeover to operation on fuel reserve and the available reserve volume and/or a remaining range are indicated by means of indicator elements which are capable of being activated by a control unit evaluating measurement signals; wherein the lack of fuel in the main tank is detected by means of a filling level transmitter and at least one additional level transmitter and corresponding signals are interlinked and evaluated in the control unit; during or after changeover to operation on fuel reserve, the control unit activates a level sensor arranged within the splash pot and evaluates the signal from said level sensor in order to indicate the reserve volume formed by the splash pot content itself.
The splash pot has preferably a sufficient volume to ensure a predetermined remaining range, for example 100 km or more, solely with its initial content. It is particularly advantageous as regards the driver's information if a continuously measuring filling level sensor is provided in the splash pot, because the actual reserve level can therefore be detected accurately as a result of the relatively simple geometry of the splash pot and can be displayed by means of the following indicator instrument. This sensor is advantageously used and activated only on fuel reserve, so that a long service life may be expected. On the other hand, the improved indication of the reserve enables the vehicle driver to utilize more effectively the fuel supply and the actual range of the vehicle, so that, where appropriate, even shorter travel times are achieved due to longer refueling intervals.
It seems particularly advantageous that, because of the improved indication of the reserve, the conventional fuel supply indicator instrument can be designed with a relatively low definition and therefore inexpensively, since differentiated and highly accurate indication becomes possible in the critical area of operation on fuel reserve. This indication may be displayed digitally in plain text so as to be capable of being read off particularly simply, whilst the low-definition indicator may be designed as a simple analog instrument. A scale changeover from low-definition to spread-out fine-definition division may alternatively also be provided.
A possibly even more convenient indicator function can be ac
Chambers A. Michael
Mannesmann VDO AG
Mayer Brown & Platt
McShane Thomas L.
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