AU2014100363A4 - Automotive fuel gauge senor - Google Patents

Abstract

Abstract An automotive fuel gauge sensor has at least one reference unit and one measuring unit working together for measuring the fuel level, and the reference unit detecting the fuel electrical feature variation for the fuel level measurement compensation, and the fuel level for the reference unit remaining stable while measuring, and the measuring unit detecting the fuel level by measuring the fuel electrical feature. *:10 - - ~-.~--'-'--" -- ------ ------- --- ------- ------- ------ 3'--33

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT AUTOMOTIVE FUEL GAUGE SENOR The following statement is a full description of this invention, including the best method of performing it known to me: 1 AUTOMOTIVE FUEL GAUGE SENSOR Most of the automotive fuel gauges are using a floater and mechanical arm driving a varistor to measure the fuel level. It is neither accurate nor reliable. Automotive fuel gauge sensor in accordance with this invention comprises a sensor structure which has at least one reference tube for medium - the fuel and temperature compensation to the fuel level measurement, one measuring tube detecting the fuel level, and the reference tube being filled up by the fuel pump or merged into the fuel, and little holes on one or both end of the tubes for the fuel or air going through as damper, and at least one insulator inside each tube locating and supporting a measuring wire, and the metal tubes also working as measuring reference ground, and the measuring wire working as the measuring electrode. The automotive fuel gauge sensor may measure either the capacitance or resistance of the fuel inside the tubes to detect the fuel level. The dielectric or resistive coefficient of the fuel may vary quite much with the fuel composition and its temperature. Normally the measuring tube and the reference tube can be identical in shape and length for better compensation accuracy. The reference tube can be filled up by the fuel pump while working or merged into the fuel. The reference tube will provide a reference to the measuring tube to compensate for the fuel type and the temperature variation. The little dumping hole on the reference tube and a fuel inlet dumper will limit the fuel amount going through, so the fuel pump is less affected by the extra loading. If the reference tube is merged into the fuel, the two ends of the tube should be open to allow the fuel going through the tube freely and so no dumping required. The little dumping hole on the measuring tube will reduce the fuel level change inside the tube for a stable fuel level measurement.

2 For a new fuel gauge system, the identical reference and measuring tubes can be installed inside the fuel tank. The fuel pump needs an extra outlet link to the reference tube and filling up the reference tube while normal operation. The over filled fuel in the reference tube will go back to the fuel tank directly through the little dumping holes on top of the tube. The dumping hole may release the fuel pressure inside the reference tube to limit the fuel leaking possibility. A merging reference tube can be used inside the fuel tank. The merging reference tube might be short for easy installation. The merging reference tube sensor can be good for an existing fuel tank system as fuel gauge upgrade. For the existing fuel tank system, an external reference tube can be used. The external reference tube may be in serial or parallel linked with the fuel pipe, and so the reference tube may be filled up by the fuel pump while normal operation. The fuel inlet for the reference tube should be in a lower location, and the fuel outlet - especially the little dumping hole or little hose or little tube for the reference tube should be in a higher location so the air inside the tube may come off the tube from the outlet and not affect the measurement. The fuel outlet for the reference tube may go back to the fuel tank together with the measuring tube on a sealing terminal. And the sealing terminal may have a sealed collecting channel back to the fuel tank just in case if the reference tube might leak from the wire terminal. The reference and measuring tubes should be built with electrical conductive material and so the tubes can be used as the measuring electrode as well as the electrical shield for the internal measuring wire. For capacitance measurement, the tubes and wires might be insulated with the fuel, and especially the wires should be an insulated wire such as enamel wire for better measurement result. And the connection cable from the wire terminal to the electronic circuit should be as shorter as possible due to the cable capacitance may affect the result. However for the resistance measurement, the tubes and wires must be conductive directly with the fuel. The length of the connection cable 3 from the wire terminal to the electronic circuit would not affect the measurement too much. So the merging reference tube would be good for the resistance measurement. For either new or improvement fuel gauge system, a fuel inlet pipe and the reference and measuring tubes going inside the fuel tank together from the top seal may have less trouble in fuel leaking and be easy for structure seal. And the internal structure may have better performance and be protected well. A triplet can be added on the fuel outlet from the fuel tank to supply the reference tube. The fuel may go back to the fuel tank directly through the dumping holes on top of the reference tube when overflowing. The stainless steel tube could be the best option for both reference and measuring tubes. The wire inside the tube can be in different format. For the capacitance measurement, the wire can be fuel resistance type enameled or insulated conduction wires. The wire end should be well insulated if it is merged in the fuel. A double tubes or wires structure can be used to keep the both wire ends off the fuel. The double tubes may double the measurement sensitivity as well. Or the both wire ends are kept on top of the tube by using double wires structure. The invention may be better understood with reference to the illustrations of embodiments of the invention which: Figure 1 is a sectional elevation of a simplified structure of a fuel gauge sensor with both reference and measuring tubes in a fuel tank. Figure 2 is a sectional elevation of a simplified structure of a fuel gauge sensor with both reference and measuring tubes in a fuel tank, and the reference tube is on bottom of the tank merged in the fuel. Figure 3 is a sectional elevation of a simplified structure of a fuel gauge 4 sensor with only measuring tube in a fuel tank and a reference tube is in outside of the fuel tank. Figure 4 is a sectional elevation of a simplified structure of a fuel gauge sensor with both reference and measuring tubes in a fuel tank, and the reference tube is filled by a pipe from outside of the fuel tank. Figure 5 is a sectional elevation of a simplified structure of a fuel gauge sensor part with double tubes. In figure 1 ~ 4, reference tube 1 and measuring tube 2 may be in different arrangement. Dumping holes 3 on the reference tube 1 or the measuring tube 2 allow air and/or fuel going through slowly. Little insulators 4 locate sensor wire 5 inside the reference tube 1 or the measuring tube 2. Fuel tank 6 has a hole or an adapter for the sensor system installation. Fuel inlet 7 supplies the reference tube 1. Fuel may go back to the fuel pipe through fuel outlet 10 or to the fuel tank through a pipe 11 or dumping hole 3. Seal 8 on one end of the tube 1 or 2 keeps the system sealing and stops the fuel leaking to PCB 9 - the printed circuit board for the fuel level measurement. Figure 1 ~3 are the basic concept arrangements for the automotive fuel gauge sensor. The figure 1 shows the reference and measuring tubes being installed inside the fuel tank. The reference tube may link to the fuel pump directly inside the fuel tank. It will have less trouble as all joints inside the tank so no leaking issue. The figure 2 shows the reference and measuring tubes being installed inside the fuel tank. And the reference tube is merged in the fuel. It does not need an extra connection to the fuel pump. The problem might be that the reference tube is far from the measuring circuit. And the bottom space or shape in the fuel tank may be not suitable for the reference tube. The figure 3 shows only the measuring tubes being installed inside the fuel tank. The reference tube is in outside the fuel tank. The system may be too 5 complex to be used in practice. The reference tube might have higher pressure inside, so the seal would be complex too. Figure 4 is a practical structure design concept. The reference tube may be filled up from the fuel outlet outside the fuel tank. The original fuel tank structure is not changed. So it can be used for upgrading an existing or new fuel gauge system. As in the drawing, the sensor wires are wound back to the top to keep the wire terminals off the fuel. This could be a good option for the wire insulation. Figure 5 shows another option to keep the wire terminals off the fuel. There are some structure details showing the little parts in figure 4 and 5. The system configuration can be different based on the basic invention concepts including mechanical structure, fluid mechanics, material and electronics. This invention can be widely used in many different fields for fluid level measurement. This fuel gauge principal may have high resolution for the fuel level measurement. But the fuel level can be affected very much by the road condition. To install the measuring tube in center of the fuel tank will reduce the influence of the road condition. The modern vehicle has the angle information which may be used to correct the measurement result. This could be a key for the advanced modern system.

Claims (5)

1. An automotive fuel gauge sensor has at least one reference unit and one measuring unit working together for measuring the fuel level, and the reference unit detecting the fuel electrical feature variation for the fuel level measurement compensation, and the fuel level for the reference unit remaining stable while measuring, and the measuring unit detecting the fuel level by measuring the fuel electrical feature.

2. An automotive fuel gauge sensor as claimed in claim 1 has at least one reference tube and one measuring tube with electrical wire inside the tubes to measure the capacitance or resistance of the fuel inside the tubes for measuring the fuel level in the fuel tank, and the reference tube being filled up with the fuel as reference for measurement compensation.

3. An automotive fuel gauge sensor as claimed in claim 1 or claim 2 uses the fuel pump to fill up the reference unit or tube.

4. An automotive fuel gauge sensor as claimed in claim 1 or claim 2 or claim 3 has reference tube and measuring tube installed inside the fuel tank, and at least one little dumping hole on top of each tube, and at least one insulator in each tube locating the measuring wire.

5. An automotive fuel gauge sensor as herein before described with reference to the description and/or figure 1 ~ 5 of the accompanying drawings. DONGNING ZHANG 13 APRIL 2014