ACOUSTIC MONITORING DEVICE FOR FUEL QUALITY

Abstract

Within the scope of the invention, a device for monitoring the quality of a fuel stored in a fuel tank has been developed. The main field of application is diesel-operated vehicles. The fuel is therefore preferably diesel fuel. The device is defined by the fact that means for determining the boiling point of the fuel are provided. Furthermore, a method for monitoring the quality of a fuel stored in a fuel tank has also been developed within the scope of the invention. The main field of application is diesel-operated vehicles. The fuel is therefore preferably diesel fuel. The method is defined by the fact that the boiling point of the fuel or a deviation of this boiling point from a normal value is measured. During the analysis of real injection pumps which have failed it has been detected that an excessively low boiling point of the fuel can cause the fuel to outgas. As a result, bubbles in which the necessary lubrication is no longer provided locally form in the injection pump. Furthermore, the lubricating effect is dependent on the fuel having a certain minimum viscosity. A low boiling point is also correlated with a low viscosity. Therefore, overall, the boiling point (initial boiling point, IBP) is a particularly good indicator especially of those deviations from standard values for the fuel which entail particularly costly damage.

Claims

1. A device for monitoring the quality of a fuel (3) stored in a fuel tank (1), characterized in that means (2, 2a, 5) for determining the boiling point of the fuel (3) are provided.

2. The device as claimed in claim 1, characterized in that the means comprise a transmitter (2) and a receiver (2a) for ultrasound.

3. The device as claimed in claim 2, characterized in that the transmitter (2) and the receiver (2a) are coupled to the fuel (3).

4. The device as claimed in claim 3, characterized by such an arrangement of the transmitter (2) relative to the fuel tank (1) that the transmitter focusses the intensity of the ultrasound on at least one point in the interior of the tank.

5. A method for monitoring the quality of a fuel (3) stored in a fuel tank (1), characterized in that the boiling point of the fuel (3) or a deviation of said boiling point from a normal value is measured.

6. The method as claimed in claim 5, characterized in that ultrasonic waves are passed through the fuel (3) and the intensity of the ultrasound emitted by the fuel (3) is measured depending on the stimulation amplitude (U) and frequency-dependently as a measure of the boiling point.

7. The method as claimed in claim 6, characterized in that the number and intensity of microscopic vapor shocks that arise during the dissolution of vapor cavitation bubbles (4) is/are measured.

8. The method as claimed in claim 7, characterized in that frequency components of the ultrasound emitted by the fuel (3) above a cutoff frequency are assessed as being caused by microscopic vapor shocks.

9. The method according to claim 6, characterized in that the number and intensity of the dissolution events of gas bubbles that have been formed by gases dissolved in the fuel (3) is/are measured.

10. The method as claimed in claim 9, characterized in that frequency components of the ultrasound emitted by the fuel (3) below a cutoff frequency are assessed as being caused by dissolution events of gas bubbles.

11. The method according to claim 5, characterized in that a reduced boiling point of the fuel (3) is assessed as a signal of contamination with gasoline, water or air.

12. A fuel supply system comprising a fuel tank (1) for storing fuel (3), an injection pump (11) and a fuel line (10) leading from the fuel tank (1) to the injection pump and that can be shut off by a valve (9), characterized in that the valve (9) is connected by a control line (8) to a device for carrying out a method according to claim 6, so that the valve (9) is shut off if the quality of the fuel (3) does not meet a predetermined condition.

13. The device as claimed in claim 1, wherein the device is for a diesel powered vehicle.

14. The device as claimed in claim 2, characterized in that the transmitter (2) is coupled to the fuel (3).

15. The device as claimed in claim 2, characterized in that the receiver (2a) is coupled to the fuel (3).

16. The method as claimed in claim 5, wherein the method monitors the quality of a fuel stored in a fuel tank of a diesel powered vehicle.

17. The method as claimed in claim 6, characterized in that the number of microscopic vapor shocks that arise during the dissolution of vapor cavitation bubbles (4) are measured.

18. The method as claimed in claim 6, characterized in that the intensity of microscopic vapor shocks that arise during the dissolution of vapor cavitation bubbles (4) is measured.

19. The method according to claim 6, characterized in that the number of the dissolution events of gas bubbles that have been formed by gases dissolved in the fuel (3) are measured.

20. The method according to claim 6, characterized in that the intensity of the dissolution events of gas bubbles that have been formed by gases dissolved in the fuel (3) is measured.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further measures that improve the invention are described in detail below together with the description of the preferred exemplary embodiments of the invention using a figure.

[0025] Exemplary embodiments

[0026] In the figure:

[0027] FIG. 1 shows an exemplary embodiment of a device according to the invention.

DETAILED DESCRIPTION

[0028] FIG. 1 shows an exemplary embodiment of the device according to the invention for protecting the injection pump 11 against unsuitable fuel. The fuel tank 1 is filled to about two thirds with fuel 3. In this case, it is diesel fuel. A piezoelectric thickness oscillator 2 that operates as a receiver 2a at the same time is disposed at the lowest point of the tank. A sinusoidal alternating voltage with a constant stimulation frequency and amplitude U increasing with time is applied to the thickness oscillator 2 by drive electronics 5. The sinusoidal time profile of the alternating voltage can also be replaced by a different time profile, for example a square wave profile. At alternating times with the stimulation, the ultrasound emitted by the fuel 3 is detected with the thickness oscillator 2 operating as a receiver 2a. Said signal is delivered to a measurement instrument 7 via a high pass filter 6 consisting of a capacitor C and a resistor R. Instead of said analog high pass filter, digital signal processing can be used.

[0029] From a defined stimulation amplitude U, vapor cavitation bubbles 4 that are filled with fuel vapor form in the fuel 3. From the points 4a at which vapor cavitation bubbles 4 collapse, ultrasound propagates towards the receiver 2a. Said ultrasound contains particularly many high-frequency components that can pass through the high pass filter 6. The stimulation amplitude U at which the signal at the measurement instrument 7 exceeds a predetermined threshold value is assessed as a measure of the boiling point or vapor pressure of the diesel fuel 3. Only if said boiling point or vapor pressure lies within a normal range will the solenoid valve 9 in the fuel line 10 be opened via a control line 8 emanating from the measurement instrument 7. This enables fuel to pass from the tank 1 into the injection pump 11. If contamination of the fuel 3 is detected, the solenoid valve 9 remains in the position thereof shown in FIG. 1 and the injection pump 11 is protected against damage.