DE102006054247A1 - Fuel tank's existing fuel amount determining system for motor vehicle, has processor unit computing existing amount of fuel in fuel tank for filling conditions between filling levels, and indicator provided for indicating amount of fuel - Google Patents

Abstract

The system has a measuring device (4) for measuring an amount of fuel above a filling level (N1) and below another filling level (N2) lying under the filling level (N1). A processor unit (8) computes an existing amount of fuel in a fuel tank (1) for filling conditions between the filling levels. An indicator (11) is provided for indicating the amount of fuel. The processor unit determines a difference between the computed fuel amount and a measured amount of fuel after falling below the filling level (N2). Independent claims are also included for the following: (1) a method for determining the amount of fuel (2) a computer program, which can be directly stored in the digital memory of a computer to execute a method for determining the amount of fuel (3) an electromagnetic signal with modulated data, which represent a computer program to execute a method for determining the amount of fuel (4) a computer program product.

Description

The The invention relates to a system for determining the in a fuel tank of a Motor vehicle existing amount of fuel.

fuel Gauge in a motor vehicle inform the driver about the existing in the fuel tank Fuel volume and allow him, in addition the range of the motor vehicle, of the existing in the motor vehicle container Fuel volume depends, estimate. At present becomes the existing fuel volume the driver usually in analog form by means of a needle, which over a mostly rough scale is shown. Here are analogous Display devices typically have a display area for safety reasons on, which specifically as a reserve level is marked.

The Display of the existing fuel quantity sets first their Measurement ahead, which is difficult in a complex geometry of the fuel tank can shape. The cause is that the fuel tank is at a complex geometry several hydrodynamically decoupled chambers can have. this leads to that when measured in a first chamber, a low Level level present can. Due to the decoupling, however, a high filling level can also be achieved present in a second chamber. The sizes of the respective chamber volumes then determine what total fuel is available. For the correct indication in such cases usually in each of these Chambers of the fuel tank made a measurement and are the individual readings with a Calculator unit added to a total value. For the utilization of the Chamber volumes each chamber has a corresponding pump, e.g. a venturi, with which the fuel is ultimately promoted to calming pot.

The DE 10 2005 055 092 A1 describes a level indicator system for a motor vehicle. A fill level measuring device measures the existing fuel volume with a high measurement accuracy above a measurability limit MG. Below this measurable limit, the existing fuel volume is calculated based on fuel consumption. The measured amount of fuel on the one hand and the calculated fuel amount on the other hand are displayed with two different display devices.

It is an object of an embodiment of the Invention, a simplified system for determining the amount of fuel present in a fuel tank provide.

The solution This object is achieved by the features of the independent claims. advantageous Developments and other embodiments result dealing with the characteristics of dependent Claims.

One The first aspect of the invention relates to a system for determining the in a fuel tank existing fuel quantity. The system includes a measuring device for measuring the amount of fuel above a first level level N1 and below a second below the first level level second filling level N2 and further comprises a computer unit, which for levels between the two level levels N1, N2 calculates the existing fuel quantity.

At the Use of the system results according to a second aspect of Invention A method for determining which is present in a fuel tank Fuel quantity. In the method, a measurement of the amount of fuel takes place above a first fill level N1 and below a second below the first level level N1 filling level N2. Between the two level levels the fuel quantity is calculated.

The Measuring device is located in a selected chamber of the fuel tank, the one can have complex bottom geometry. The reading taken in the selected chamber won, may representative of this for the in total in the fuel tank be existing fuel amount. The measuring device serves with it the measurement of the total amount of fuel in the fuel tank. Is the fuel tank full, so plays when measuring the amount of fuel present the geometry of the fuel tank usually not matter. Reason is that the hydrodynamic decoupling through a jagged, in different chambers K1, K2 ... divided bottom of the fuel tank overcome the high filling level becomes.

Of the For the sake of simplicity assume that a fuel tank has two chambers K1 and K2 has and that the measuring device is located in the chamber K1. In this case, there is for the Fuel tank a level level N1, below which the two chambers hydrodynamically decouple are. The decoupling results from the presence of a corresponding wall between the chambers responsible for levels below level N1 a back and forth prevented by fuel between the two chambers.

If fuel is subsequently consumed, the total quantity of fuel present in the fuel tank drops to a level below that Level levels N1. If the measuring device is located in the chamber K1 and if there is a pump, or alternatively a Venturi nozzle with supply line from the fuel system, for conveying fuel from the chamber K1 into a calming pot, the amount of fuel in the chamber K1 decreases. Because of the hydrodynamic decoupling of the two chambers, however, this is not the case in the chamber K2. If now a pump located in the chamber K2 is activated, it pumps the fuel out of the chamber K2 or into the chamber K1. During this evacuation process, the amount of fuel measured in the chamber K1 does not correspond to the actual amount of fuel present in the entire fuel tank due to the hydrodynamic decoupling. Namely, during the pumping operation, the amount of fuel in the chamber K1 remains constant while the total amount of fuel remaining decreases.

To the emptying of the chamber K2 is the entire existing in the fuel tank Amount of fuel in the chamber K1. The level of the whole Fuel tank is then N2. If more fuel is consumed, so is the of the Measuring device in the chamber K1 measured amount of fuel always the total in the fuel tank existing fuel quantity.

For level levels between N1 and N2 the available fuel quantity of one Calculated computer unit. This will be a measuring device in the Chamber K2 saved, making the system easier, cheaper and cheaper less prone to error. The saved measuring device will continue to be for you electrical leads and is saved in this respect assembly costs. Also, no coordination of signals for two measuring devices is required.

Of the A person skilled in the art will recognize that the above statements to the case of n> 2 Generalize chambers, where n is an integer. So can For example, pumps the fuel from two chambers K2 and K3 pump to chamber K1 and the fuel pump located in K1 pump to the calming pot. In all cases, the measuring device be in that chamber in which also the calming pot or is conveyed from the fuel in the sedative pot.

In a second embodiment the system has exactly one measuring device.

The System of the last paragraph is particularly well suited for one Saddle tank, so a fuel tank with a first chamber, the above communicating a saddle with a second chamber, and in which due to the hydraulic design fuel of a chamber K2 is conveyed into the chamber K1. When saddle tank are the ratios designed particularly simple, since one measured in the first chamber K1 Filling height above the lower saddle surface by calibration directly reflects the total amount of fuel in the fuel tank. The chamber K1 takes over for the chamber K2 a similar Function as the calming pot for the chamber K1. Is the Measuring device in the first chamber, so that corresponds to the difference (N1-N2) the two level levels about the volume of the chamber K2. On the measuring device in the chamber K2 can then be dispensed with.

In a further embodiment the calculation of the existing fuel quantity is based on Engine consumption data made.

at This procedure can be a computer, for example the on-board computer of the motor vehicle, the opening times Add up the injectors of the engine and the consumed Calculate fuel quantity with consumption per unit of time. Starting from a measured value M1 at level level N1 becomes at sinking level consumed fuel quantity V is calculated and will be between the two filling level N1 and N2 the amount M1-V brought to the display. This procedure is particularly simple because the on-board computer has the data already available anyway and to implement only an adapted on-board computer software is required.

Farther is an embodiment provided that the system has a display device for displaying have the amount of fuel and a switching device. The switching device switches when falling below the first fill level N1 at the Display device of supplied measured values supplied to the measuring device calculated values of the computer unit.

By said switching when falling below the first level level N1 is guaranteed that the display, usually an analog display, with a needle, too with further fuel consumption, a drop in the existing in the fuel tank Fuel quantity shows and the driver is not by a constant Display value, how he would adjust himself with a saddle tank, or a fake one Display value is irritated.

Furthermore, an embodiment is proposed in which, when the second fill level N2 in the display device falls below the second fill level N2 in the display device, the switching device switches over from supplied calculated values of the computer unit to supplied measured values of the measuring device. This additional functionality has the consequence that when Unterschrei th second level level N2 is again brought to the current state of the art over the calculated value more accurate reading displayed. This is particularly useful when the second level level N2 is close to the reserve level, since then the driver has a particular interest in the most accurate indication, to avoid lying down because of fuel shortage.

Further is an embodiment provided in the system has a computer unit, which after Falling below the second level level N2 a difference between calculated fuel quantity and measured Determined fuel quantity, the obtained by calculation and displayed display value with further fuel consumption such that difference is corrected up to a calibrated one filling level towards zero.

at this approach is taken into account that the fuel quantity calculation, at least as of today technology, between the two level levels N1 and N2 inaccurate is as their measurement, and that then when switching in the sense of the penultimate paragraph a jump in the display value can occur. To avoid this, will also be below the second level levels N2 only the calculated fuel quantity is displayed. The above Difference corresponds with high accuracy of measurement roughly the error of Display value, which is successively reduced to zero by the correction mode becomes. This will ensure that afterwards at a level level near the reserve level an exact value is displayed which the driver can trust. As stated above is with such small quantities in the fuel tank an accurate knowledge of the residual amount is particularly important to a premature Engine standstill due to lack of fuel to avoid.

One third aspect of the invention relates to a fuel tank with the above system, wherein the fuel tank a Saddle tank can be.

It It goes without saying that the above method is performed computer-aided can. Accordingly, relates Another aspect of the invention relates to a computer program that directly into the digital memory of a computer, e.g. an on-board computer, can be loaded and includes software code sections with which the above process is carried out at least in part can. The method can be embodied on a data carrier and then present a computer program product that is on a computer readable disk is stored and includes computer readable program means having a Computer, e.g. cause the aforementioned on-board computer to perform the procedure described above when the program is run on a Computer running becomes. Furthermore, the computer program can also be in the form of an electromagnetic Signals embodied or realized, as a carrier has modulated data containing the aforementioned computer program represent.

Further Features and advantages of the claimed invention will be apparent from the following detailed description with reference to the accompanying drawings recognizable, which are given below as non-limiting examples are. Here, the use of reference numerals in the figures not to be understood that the reference numerals denote To limit the scope of the claimed invention. It shows:

1 schematically a fuel tank with a system for determining the amount of fuel contained in it.

1 schematically shows a trained as a saddle tank fuel tank 1 , It has two chambers K1 and K2 and a saddle S connecting the two chambers K1 and K2. There is also a calming pot in the left-hand chamber K1 2 that has a flange 3 is sealed to the outside.

After refueling, the measuring device can 4 in the chamber K1 for filling levels h between h _max and N1 measure an amount of fuel that is representative of the total amount of fuel. It determines, as is customary, a filling level or a level, which is measured in millimeters, for example. By means of a test, the fuel level in liters can then be assigned to the level. It is therefore, as well as in the description as a whole, the term "fill level" synonymous with the term "fuel quantity".

If the level falls below level N1, the two chambers K1 and K2 are hydrodynamically decoupled. This means that in the dormant state and without tilting the fuel tank 1 no fuel can pass from one chamber to the other.

At the latest when reaching the level N1, the pump 5 or other means such as a Venturi nozzle in the chamber K2 activated with the fuel via a hose 6 is promoted to the chamber K1. With further fuel consumption, the measuring device 4 because of the present hydrodynamic decoupling of the two chambers K1 and K2 always determine the same measured value, which the Füllstandsni corresponds to N1. The measured value is therefore meaningless.

If the chamber K2 is pumped empty, this corresponds to a level level N2 (= maximum N1). Now is the entire amount of fuel in the fuel tank - except for that in the calming pot 2 existing quantity - identical to the amount of fuel in the chamber K1. The measured value of the measuring device 4 thus reflects the true amount of fuel in the fuel tank 1 contrary.

The measuring device 4 is over a through the flange 3 performed data cable 7 with a computer unit 8th connected. The computer unit 8th has a microprocessor 9 with allocated memory 10 , For a fuel quantity greater than N1, the measured value of the measuring device 4 on the display device 11 brought to the display. The computer unit calculates between N1 and N2 8th the amount of fuel remaining from a calibration value M1 by subtracting the amount of fuel injected into the engine V1. The computer unit 8th is thus at the same time a switching device 12 which switches in the display device from supplied measured values of the measuring device to supplied calculated values or vice versa.

Below the level level N2, the chamber K2 is empty. The measuring device 4 returns the true amount of fuel in the entire fuel tank 1 at. In this area brings the computer unit 8th continue to display the calculated value on the display device. As measured values continue to be supplied, they continue to calculate the difference D = (calculated fuel quantity - measured fuel quantity). This difference D is successively brought to zero for a further decreasing level up to a calibration. This implies that, near the reserve fill level, the displayed value returns to the measurement value of the measuring device 4 is. This value is more accurate than that of the computer unit 8th calculated value. Thus, the display is just when the accuracy is particularly important for the driver so as not to be left because of fuel shortage.

For the use of the system is in the working memory 10 the computer unit 8th a computer program loaded with the taking advantage of the measuring device 4 Fuel quantities above a first level level N1 and below a below the first level level lying second level levels N2 are measured and displayed. For levels between the two levels, the fuel quantity is calculated as described above. As stated above, the calculation can be made below the level if required. As is generally customary, the computer program can be stored on a data carrier such as a CD or a DVD or transmitted with an electromagnetic signal via a radio link, for example via WLAN, or via cable, for example via the Internet.

Even though above specific embodiments The person skilled in the art will recognize that the description these embodiments does not have the purpose to limit the invention in the form specified. The Rather, the invention is intended to cover all modifications, equivalents and alternatives which fall within the scope of the claimed invention.

1

Fuel tank

2

swirl pot

3

flange

4

measuring device

5

pump

6

tube

7

data cable

8th

computer unit

9

microprocessor

10

random access memory

11

display device

12

switching device

K1

chamber

K2

chamber

S

saddle

Claims (14)

System for determining in a fuel tank ( 1 ) amount of fuel, comprising a) a measuring device ( 4 ) for measuring the fuel quantity above a first fill level (N1) and below a second fill level (N2) below the first fill level, b) a computer unit ( 8th ) which calculates the amount of fuel present for levels between the two levels (N1, N2). System according to claim 1, wherein exactly one measuring device is provided. System according to one of the preceding claims, in the computer unit is designed, the calculation of the existing Fuel quantity based on engine consumption data make. System according to one of the preceding claims, in which a display device ( 11 ) for displaying the amount of fuel and a switching device ( 12 ) are provided, wherein the Schaltvorrich tion when falling below the first filling level in the display device of supplied measured values of the measuring device to supplied calculated values of the computer unit switches. The system of claim 4, wherein the switching device when falling below the second level level in the display device supplied Calculated values of the computer unit to supplied measured values of Messein direction switches. System according to one of the preceding claims, in the a) the computer unit is designed to fall below the second level level a difference between calculated fuel quantity and measured Determine fuel quantity and b) the data obtained by calculation and display value displayed by the display device at further To correct fuel consumption such that said difference up to a calibrated level towards zero. Fuel tank with a system according to one of the preceding claims. Fuel tank according to claim 7, which is a saddle tank. Method for determining in a fuel tank ( 1 ) amount of fuel comprising the steps of: a) measuring the amount of fuel above a first level (N1) and below a second level (N2) below the first level; b) calculating the level of fuel for levels between the two levels. Method according to claim 9, wherein the calculation the amount of fuel is based on engine consumption data. Method according to one of the preceding claims, further comprising the following steps, after falling below the second Level levels are carried out: a) Calculate the amount of fuel available b) determining a Difference between calculated fuel quantity and measured fuel quantity c) Displaying the calculated amount of fuel, leaving for one decreasing fuel quantity the display value is corrected in such a way that difference is up to a calibrated level level successively goes to zero. Computer program that directly into the digital memory a computer can be loaded and includes software code sections, with which the method according to a at least the previous claims partially performed can be. Electromagnetic signal with modulated data, which represent a computer program according to claim 12. Computer program product running on a computer readable disk is stored and includes computer readable program means cause a computer to perform a procedure according to one of the previous ones claims perform, if the program is running on a computer.