DE10057934A1 - Measuring liquid volume in container, especially fuel tank, involves using liquid level determined by detecting proportion of enclosing walls off container covered by liquid - Google Patents

Abstract

The method involves measuring the level of liquid (3) in an internal volume of the container (1) defined by enclosing walls to obtain corresponding level information and deriving the liquid volume from the level information and geometric information. The level is determined by detecting the proportion of the enclosing walls covered by the liquid. AN Independent claim is also included for the following: (a) an arrangement for measuring a liquid volume in a container, especially a fuel tank.

Description

The present invention relates to a method and a corresponding device for measuring the volume of liquid in a container. In particular The present invention relates to a method and a corresponding device for measuring the volume of fuel in a fuel tank.

The direct measurement of the fuel volume or fuel supply is in motor vehicles very difficult. Suitable inexpensive measuring methods have so far not been possible push through. Therefore, the level in the fuel tank is conventionally measured and over a level-volume characteristic of the used Fuel tanks converted into the fuel volume in the fuel tank.

For example, in US 4,739,494 a method for measuring the in one Fuel tank located fuel volume according to the preamble of claim 1 described, with the help of several grid-like over the bottom of the fuel tank distributed pressure sensors, the level at the respective measuring point is determined becomes. Based on the measured values of the individual pressure sensors, the Level of the liquid level in the fuel tank is determined, so that together with Information about the geometry of the fuel tank that in the fuel tank located fuel volume can be calculated.

Similar processes are also in DE 42 01 301 C2 and DE 197 04 683 A1 described.

The previously explained conventional method for measuring that in a fuel tank located fuel supply or fuel volume has in common that one A large number of sensors arranged at discrete measuring points for measuring the Level, d. H. the level of the liquid at the individual measuring points be used. The use of such a variety of discrete sensors has, however, an increase in the manufacturing costs of the corresponding measuring systems Episode. In addition, a relatively complex evaluation logic or evaluation circuit required to share the measurement signals supplied by the individual sensors evaluate and into the fuel volume in the respective fuel tank to be able to convert. In addition, at such a point Measured value acquisition at several measuring points within the fuel tank Insufficient consideration is given to the tank shape. This is particularly problematic because increasingly complex tank forms are offered.

The present invention is therefore based on the object of a method and a Device for measuring in a container, in particular a fuel tank, to provide liquid volume or liquid supply with which the problems previously described can be avoided. In particular, a Method and an apparatus for measuring in a container, in particular a fuel tank, liquid volume located, which a simple and inexpensive determination of what is in the container Allow liquid volume and also precise measurement results for complicated deliver assembled container shapes.

This object is achieved by a method with the features of Claim 1 and a device with the features of claim 5 solved. The Sub-claims each define preferred and advantageous embodiments of the present invention.

According to the invention for measuring the in a container, in particular a Fuel tank, liquid volume is not a selective measurement of the Level proposed at several discrete measuring points within the container, but to measure the fill level are portions of the conversion of the container detects which are covered by the liquid.

For example, a hose-like, tube-like or film-like one can be used for this purpose continuous sensor can be used, which is flexible along the inside of the Conversion of the container used in each case can be relocated and thus the total distance covered by the liquid on the inside of the transformation of the Can capture container in a cross-sectional plane of the container. Based on Geometry information that can describe the interior of the container the volume of liquid in the container is then determined therefrom become.

In particular, a capacitive level sensor can be used as the sensor, which is a plurality of common in the longitudinal direction of the sensor Carrier material, for example a flexible circuit board or the like, arranged includes capacitive sensor elements.

The measurement or detection proposed in the context of the present invention of the liquid covered portions of the wall of the container compared to the discrete level measurement described at the beginning on several Measuring points have a number of advantages. A major advantage of the present The invention is that properties can be achieved that a volume measurement to come close. In particular, the present invention is also complicated constructed container shapes, for example for multi-chamber tanks (e.g. saddle tanks), Suitable, since only one sensor can be used, which over all chambers is relocated. In addition, the present invention allows the compensation of a Inclination of the container or when using the present invention in the Automotive technology a vehicle inclination, since with the help of the invention used sensors also make a statement about the angle of inclination Liquid level in the container can be obtained. Likewise, a Sloshing of the liquid, expansion of the container and tolerances are compensated become. This is particularly advantageous in motor vehicle technology, since here in the Usually the fuel tank expands in height with increasing service life, which at Application of conventional measuring methods or measuring systems to corresponding ones Errors in the determination of the fuel supply leads.

The present invention is described in more detail below with reference to preferred Embodiments explained with reference to the accompanying drawings. there In particular, the present invention is based on the preferred application Determination of what is in a fuel tank of a motor vehicle Fuel supply or fuel volume described. The present invention is however, of course, in principle of any container type for measuring the in the volume of any liquid can be used in the respective container.

Fig. 1 is a cross-sectional view showing a fuel tank including a device for measuring the volume of fuel contained in the fuel tank according to a preferred embodiment of the present invention,

FIG. 2 shows an illustration to clarify the functioning of the present invention using the example of a cuboid fuel tank,

Fig. 3 is a drawing to show the independence of the volume measurement showed the invention of the inclination angle of the fluid or fuel surface, and

Fig. 4 shows the representation of various capacitive level sensors in plan and cross-sectional view, which can be used for example in the context of the present invention.

In Fig. 1 a vertical cross section through the fuel tank 1 of a motor vehicle. In the fuel tank 1, a fuel pump 2 is arranged, which serves for conveying the fuel 3 located in the fuel tank. 1 A fill level sensor 4 is installed along the cross-sectional line on the inside of the conversion of the fuel tank 1 , which level sensor 4 particularly follows the shape of the conversion of the fuel tank 1 . For this purpose, the fill level sensor 4 can be flexibly installed as a hose, tube, film or the like on the bottom and the side walls of the fuel tank 1 , so that the fill level sensor 4 is arranged in the interior of the fuel tank 1 in a manner adapted to the tank geometry.

The fill level sensor 4 is configured in such a way that it delivers a measurement signal which is proportional to the surface portions of the fill level sensor 4 covered with the fuel 3 . The measurement signal of the fill level sensor 4 is thus correspondingly proportional to the path or distance portions of the conversion of the fuel tank 1 covered by the fuel 3 in the corresponding cross-sectional plane in which the fill level sensor runs. The measurement signal supplied by the fill level sensor 4 is fed to an evaluation logic or evaluation circuit 5 , which accesses a memory 6 in which geometric information about the tank geometry of the fuel tank 1 used in each case is stored. The evaluation logic 5 can determine the fuel volume V located in the fuel tank 1 or the corresponding fuel supply with the aid of the fill level and geometry information thus present. The function of the evaluation logic 5 can be performed, for example, by a suitable microprocessor, which does not have to be arranged in the vicinity of the fuel tank 1 , but can be accommodated in a combination instrument.

In the exemplary embodiment shown in FIG. 1, the fill level sensor 4 is laid continuously along the inside of the conversion of the fuel tank 1 . Of course, it is also fundamentally conceivable to use several individual corresponding level sensors which are laid in the fuel tank and adjoin one another. In principle, it is sufficient to arrange the fill level sensors 4 only in those areas of the fuel tank 1 where they can be covered by the fuel 3 .

In general, sensors can be used as the fill level sensor 4 , which provide a measurement signal that is dependent on the proportion of the surface of the respective sensor covered by the fuel 3 .

For this purpose, thermal sensors are suitable, for example, and as measuring sensors A heating resistor is used because the heat dissipation is covered by fuel Parts of a heating foil of this thermal sensor is larger than for air-flushed parts, so the heating resistor is a measure of the portion of the heating foil covered by fuel of the thermal sensor. One with the use of thermal sensors related problem, however, is the fact that by measuring the Heating resistor an additional fuel heating occurs.

Furthermore, optical sensors are also suitable for carrying out the present invention, for example. B. a light beam transmitted between an optical transmitter and an optical receiver is interrupted by the fuel liquid, or alternatively optical fibers are attached to the inside of the fuel tank. In the second case, depending on whether fuel is present or not, a total reflection takes place at the end of the respective optical fiber, so that by evaluating the light reflected by the individual optical fibers, conclusions can be drawn about the portions of the conversion of the fuel tank 1 covered with fuel.

Capacitive sensors are particularly suitable, the capacity of which changes depending on how large the portion of the respective sensor covered with fuel is. Various embodiments of such capacitive sensors are shown in FIG. 4, wherein these sensors can each be designed in the form of a flexible film, a flexible hose or tube and are therefore suitable for laying in a fuel tank adapted to the tank geometry.

The embodiment shown in Fig. 4 (a) is two wires or rods with spacers. According to Fig. 4 (b) are used as two sensor deposited on a support material traces. In the exemplary embodiment shown in FIG. 4 (c), two electrodes are designed in the form of a tube, the capacitance of this tube being used in combination with an oscillator or multivibrator as the measurement transducer.

The embodiment shown in FIG. 4 (d) is particularly advantageous, in which a multiplicity of capacitive sensor elements arranged next to one another on a carrier material in the longitudinal direction of the sensor are provided, so that by evaluating the capacitance of each individual sensor element it can be determined exactly whether the respective Sensor elements are covered with fuel or not. The use of several individual capacitive sensor elements at discrete positions is advantageous since the sensor formed thereby is relatively insensitive to water, dirt on the tank bottom or at times poor mixing (after a tank operation) or the like.

The exemplary embodiment shown in FIG. 4 (e) essentially corresponds to FIG. 4 (b), but a reference capacity is additionally installed on the tank bottom. According to FIG. 4 (f), similar to FIG. 4 (d), several individual capacities are formed, which are arranged without gaps over the entire fill level area within the fuel tank. The individual capacities are in particular overlapping. By determining the capacities covered by the fuel, an exact level measurement is possible. In the in Fig. 4 (g) shown embodiment, embodiments of a continuous capacitance measurement or a capacitance measurement discrete shown 4 (d) are the 4 (b) and in Fig.. Combined.

The illustration of FIG. 2 serves to illustrate the basic principle of the present invention using a simple example of a block-shaped fuel tank 1 with the height H and the width B. The FIG. 2 sensor 4 used comprises vertical sections 8, 9 and a horizontal part section 10 and is laid on the inside of the wall of the fuel tank 1 . The liquid surface of the fuel 3 located in the fuel tank 1 is shown obliquely in Fig. 2 to the geometric conditions in the case of an inclined position to make clear the corresponding vehicle. In addition, a conventional fill level measuring device 7 , for example in the form of a lever transmitter, is shown in FIG. 2.

For a 72 l fuel tank, for a fuel volume of 30 l when using the conventional fill level measuring device 7 shown in FIG. 2, the clear dependence of the measured fuel volume on the inclination angle α of the motor vehicle, shown in dashed lines in FIG. 3, results. The level detected by the level measuring device 7 is denoted by h _α in the figure. Since the fill level h _α detected by the fill level measuring device 7 is dependent on the inclination angle α of the motor vehicle, the fuel volume determined as a function of this fill level is also dependent on the inclination angle. The offset of the fill level measuring device 7 is designated by e in FIG. 2.

With the aid of the fuel volume measurement according to the invention, the fuel volume V located in the fuel tank 1 can be determined independently of the fill level. This can e.g. B. happen that the two vertically running sections 8 , 9 of the sensor 4, the fuel-covered heights a2 and a1 are measured. With this information, the angle of inclination α can be determined, so that the angle of inclination can be compensated with its knowledge.

With the tank width B, the tank length L, the measured values a2, a1 and b depending on the covered surface of the sensor sections 8-10 and the resulting inclination angle α, the following relationships apply to the fuel volume V:
If the angle of inclination α is so small that a2> 0 applies:

tanα = (a1 - a2) / B (1)

V = [(a1 + a2) / 2] .BL (2)

If the angle of inclination α is so large that a2 = 0 applies:

tanα = a1 / b (3)

V = a1. (B / 2) .BL (4)

The previously described calculation method for determining the fuel volume V relates to the case of a cuboid fuel volume assumed for the sake of simplicity. Similar calculation methods are also possible for determining the fuel volume in complicated tank shapes. REFERENCE SIGN LIST 1 fuel tank
2 fuel pump
3 fuel liquid
4 level sensor
5 evaluation logic
6 memory for storing information about the tank geometry
7 level measuring device
8-10 measuring sections of the level sensor 4
B, H Dimensions of the fuel tank 1
a1, a2, b Measured values of the level sensor 4
e Offset of the level measuring device 7
h _α level measured by the level measuring device 7
α angle of inclination of the fuel liquid
V fuel volume

Claims (11)

1. A method for measuring the volume of liquid in a container, in particular a fuel tank, (a) wherein the fill level of the liquid is measured in the interior of the container defined by a conversion ( 1 ) in order to obtain corresponding fill level information, and (b) The liquid volume in the container ( 1 ) is determined on the basis of the fill level information obtained in step (a) and on the basis of geometric information describing the interior of the container ( 1 ), characterized in that in step (a) the fill level is determined by Liquid-covered proportions of the conversion of the container ( 1 ) is measured. 2. The method according to claim 1, characterized in that in step (a) portions of the walling of the container (1) are detected, which are covered by the liquid in a vertical cross-sectional plane of the container (1). 3. The method according to claim 2, characterized in that in step (a) all of the shares of the walling of the container (1) are detected, which are covered by the liquid in the vertically extending cross-sectional plane of the container (1). 4. The method according to any one of the preceding claims, characterized in that in step (b) on the basis of the level information obtained in step (a) detects an angle of inclination (α) of the liquid in the container ( 1 ) and when determining the liquid volume (V ) is taken into account. 5.Device for measuring the liquid volume in a container, in particular a fuel tank, with sensor means ( 4 ) for measuring the fill level of the liquid in the interior of the container ( 1 ) defined by a conversion, in order to provide corresponding fill level information, and with evaluation means ( 5 ) for determining the liquid volume (V) in the container ( 1 ) on the basis of the fill level information provided by the sensor means ( 4 ) and on the basis of stored geometric information which describe the interior of the container ( 1 ), characterized in that the sensor means ( 4 ) are designed and arranged in such a way that they measure the fill level by detecting portions of the conversion of the container ( 1 ) covered by the liquid. 6. Apparatus according to claim 5, characterized in that the sensor means (4) are arranged along a line extending in a vertical cross-sectional plane of the container (1) and the walling of the container (1) following line. 7. The device according to claim 6, characterized in that the sensor means ( 4 ) on the inside of the conversion of the container ( 1 ) are arranged along the line. 8. The device according to claim 6 or 7, characterized in that the sensor means ( 4 ) comprise a sensor arranged continuously along the line. 9. Device according to one of claims 5-8, characterized in that the sensor means are designed capacitively such that the evaluation means ( 5 ) by evaluating the capacity of the sensor means ( 4 ) on the portions of the conversion of the container covered by the liquid ( 1st ) can close. 10. The device according to claim 8 and 9, characterized in that the sensor means ( 4 ) comprises a sensor with a plurality of capacitive sensor elements arranged side by side in the longitudinal direction of the sensor. 11. The device according to any one of claims 5-10, characterized in that the evaluation means ( 5 ) are designed such that they use the fill level information provided by the sensor means ( 4 ) to provide an angle of inclination (α) of the liquid in the container ( 1 ) determine and take into account when determining the liquid volume (V).