Title of Invention

FUEL MONITORING SYSTEM FOR MOTOR VEHICLES

Abstract

A system and method for monitoring fuel consumption in a motor vehicle diesel engine is disclosed. An auxiliary fuel tank is connected between the fuel supply line and the fuel return line of the diesel engine. A metering pump is provided in a fuel line connected between the main tank and the auxiliary tank. The quantity of fuel in the auxiliary tank Is detected for example at predtermined minimum and maximum levels. The fuel metering pump is started when the fuel in the auxiliary tank reaches a first predetermined level and stopped when the fuel in the auxiliary tank reaches a second predetermined level, The amount of fuel displaced by the pump over a given time period Is measured and the fuel consumption by the engine over the given time period is determined, taking into account any change of the amount of fuel in the auxiliary tank.

Full Text

1. Field of the Invention The present invention relates to fuel monitoring systems and in particular fuel monitoring systems for diesel engines of motor vehicles, such as trucks, utility vehicles and automobiles. 2. Description of Related Art Because of the increased cost of fuel for motor vehicle engines Inoluding. diesel engines, there Is a great demand for fuel monitoring systems which have only been employed in large truck fleets. Also there is an increasing demand for fuel monitoring systems in order to detect and possibly prevent fuel pilferage. Yet the cost of such systems is prohibitive for fleets of small trucks and utility vehicles, let alone automobiles. Relatively Inexpensive fuel monitoring kits for dieseJ engines have appeared on the market, but they are generally inaccurate. Such kits are not permanently installed on the vehicle, nor are they in constant operation. In diesel engines, typically, an amount of fuel much in excess of the engine's actual consumption is pumped by the fuel injection pump to the engine. Only a email proportion of the fuel pumped through a supply line is actually consumed and the balance (s reclrculated and returned to the fuel tank via a fuel return line. The temperature of the fuel in the return line is substantially higher than the temperature in the supply line because of the passage of the fuel into and out of the engine. Known monitoring systems for diesel engine fuel consumption comprise two flowmetsre, one Installed in the supply line from the fuel pump to the engine and the second In the return line to the fuel tank. Fuel consumption is not actually measured, rather the system detects the difference In the fuel flows and the resulting difference is recorded and/or displayed on a screen mounted in dashboard or transmitted to a remote monitoring centre. Since the flowmeters do not measure fuel consumption but the difference in the flow fuel in the supply and return lines, there are errors inherent in the design of flowmeters and these are compounded by the fact that two such flowmeters are used. Conventional flowmeters do not provide an accurate determination of fuel consumed. Also, the fiowmeter on the suction side of the fuel pump produces a pressure drop in the fuel supply line which may cause vaporization of fuel and thereby vapour lock In the fuel pump. Since the temperature of the fuel in the return line is much higher than the temperature of the fuel in the supply line, the mass of fuel per unit volume detected by the flowmeter in the return line is considerably less than the mass of fuel per unit volume which is detected by the flowmeter in tha supply line, This results in additional consequential errors in the fuel consumption calculated by such a monitoring system. In an attempt to mitigate this problem, the return fuel line is sometimes cooled by means of a heat transfer line in the fuel circuit or the water circuit of the vehicle or a special refrigerating unit. There is also known a Max Model 710 fuel measuring system available from Max Machinery Inc. which is intended to provide test stand fuel monitoring accuracy In a portable in-vehide unit. This system is temporarily connected to the engine with the equipment mounted on a portable stand and may for example be temporarily located in the vehicle trunk. This unit combines a fuel conditioning and metering package using a number of components outside the normal operating engine including a level controller, a special high accuracy flowmeter, exchanger, pump regulators and the like. The level controller is hooked up to engine components by hoses to temporarily bypass the flowmeter on the supply line and to connect the fuel supply line, the fuel return line and the make-up fuel line from the main fuel tank to a level controller tank equipped with a float controlled valve In order to allow entry of make-up fuel. An object of the present Invention is to provide an accurate, reliable and inexpensive fuel monitoring systems for dieeel engines. Another object of the present invention is to provide such a fuel monitoring system which may be permanent equipment for a motor vehicle, such as a truck or lorry for use as OEM or retrofitting. According to a first aspect of the invention, there is provided a fuel monitoring system for a motor vehicle diesel engine comprising an auxiliary fuel tank adapted to be connected between the fuel supply line and the fuel return line of the diesei engine. A detector detects the quantity of fuel in the auxiliary tank. A metering pump Is connected between the auxiliary tank and the main fuel tank of the motor vahicie for supplying rnetered quantities of fuel to the auxiliary tank in response to the quantity of fuel in the auxiliary tank. A sensor associated with the fuel pump provides an output corresponding to the amount of fuel pumped by the metering pump in a given time period, and a computing unit for determining the amount of fuel consumed will be the amount of fuel pumped minus the difference of the amount of fuel between the minimum and maximum levels. The measuring process repeatB Itself intermittently, The starting of a measurement period may be controlled by at predetermined points in time, e.g. beginning of the driver's shift and finish at the end of driver's shift. Alternatively, a measurement period may commence at the departure of a given run and finish at the end of that run. Where they are multiple drivers of the vehicle, the respective driving periods may be monitored separately. Obviously, there are a multitude of schemes for tailoring the system to the needs of a particular user. The magnetic pick-up 47 is connected to an on-board computing unit 50 such as a processor for processing the signals emitted by the magnetic pick-up 47 corresponding to fuel pumped by the fuel pump. The amount of fuel pumped over a given interval (plus or minus any increase or decrease of the fuel in the auxiliary tank over that interval) is also displayed on a display unit connected to the onboard computing unit 50 or transmitted by any conventional telecommunications system to a remote monitoring or control centre, e.g. when such a monitoring system is provided on each a fleet of vehicles. Such an interval may ba a run of the vehicle between a starting point and a finishing point or a driver's shift or a set chronological period, such as an hour, a day or a week. In order to calculate and then display and/or transmit the amount of fuel consumed by the engine per mile or kilometre, the odometer of the vehicle is also connected to the computing unit 50 to provide an indication of the miles or kilometres driven over a given period of time. Thus, the computing unit 50 can determine for display on-board or transmission to a remote control centre the mites or kilometres per litre or the inverse, that is the litres or gallons per a given distance, say, 100 kilometres or 100 miles. It will be appreciated that the determination of fuel consumption will be independent of driving conditions, road conditions, the slope or the terrain, ambient temperature, engine conditions, tyre pressure, the vehicle load and the like. With such accurate determination of fuel consumption, it is possible to detect pilferage and take corrective action. It will be understood that the foregoing description and examples are not limitative of the Invention, the scope and spirit of which are defined in the appended claims. to a number of rotatipne of the pump drive motor shaft. Specifically, the driven shaft is equipped with a gear wheel of the gear coupling 43, for example with 25 teeth associated with a magnetic pick-up 47. The gear wheel teeth selectively interrupt the magnetic flux from the magnetic pick-up, thereby producing output signals which are counted and correspond to the number of strokes of the piston and thereby to the quantity of fuel displaced or pumped by the metering pump. Such a metering pump is very accurate (compared with conventional flowmeters for monitoring systems which give a fuel flow indication) and provides the measurement of the fuel actually consumed, and may have a measurement error below 0.1 % and even below 0.05 %. The auxiliary tank 30 is equipped with a fuel detector or detecting means. Any suitable detecting means may be adopted including a level detector, such ae described hereinafter. Alternatively, a fuel detector which weighs the amount of fuel in the auxiliary tank or the like may be employed. As illustrated herein, the fuel detector comprises a float switch 32, known per se, having a minimum and maximum levels defined by stops 33, 34. When the float 37 reaches the minimum level, the float switch 32 emits a signal to a motor controller 41 for activating the metering pump 40. The metering pump will then pump fuel from the main tank 21 to the auxiliary tank 30, When the float 37 reaches the maximum level position, the float switch 32 emits a signal to the motor controller 41 to deactivate the metering pump. The amount of fuel consumed over the operating period of the metering pump is equal to the amount of fuel pumped by trie metering pump, plus or minus any change in the level of the fuel In the auxiliary fuel tank. In order to eliminate the need for constantly monitoring the level of fuel in the auxiliary fuel tank, the determination of fuel consumed Is made at given intervals corresponding to the starting and/or stopping of the fuel pumped and thereby the known minimum or maximum level of fuel In the auxiliary tank. If pumped fuel is determined when the fuel in the auxiliary tank is at its minimum level and then determined when the fuel In the auxiliary tank is at Its maximum level, the known difference between the minimum and maximum levels, typically between 2 and 4 litres, and preferably around 3 litres or no more than about 10 % of the total capacity of the auxiliary tank, the amount of fuel consumed will be the amount of fuel pumped plus the amount of fuel between the minimum and maximum levels. Alternatively, if the first reading is made at the maximum level of the fuel in the auxiliary tank, then the As shown, the auxiliary fuel tank Is located closer to the engine thanthe main tank 21 .and thus the suction side pressure drop will be reduced. As the auxiliary tank 30 receives the return fuel from the engine which is at a higher temperature than the temperature of the fuel in the main fuel tank 21, the auxiliary tank 30 contains a sufficient amount of fuel at all times so that the higher temperature fuel returned to the auxiliary tank 30 does not unduly increase the temperature of the fuel In the auxiliary tank 30. In the present example, the auxiliary tank 30 contains a minimum of about 25-30 litres of diesel fuel at all times. Thus, the temperature of fuel In the auxiliary tank 30 will be substantially the same as the temperature of fuel in the main tank 21, and In practice close to ambient temperature. A supply header 36 and a return header 35 are mounted in the auxiliary tank at the same level as the supply header and the return header (not shown) in the main fuel tank which are disconnected or demounted. In this case sealing plugs are installed. The auxiliary tank also has, as illustrated, a vent for preventing excess pressure in the tank and a cap and filling tube for Initially filling the auxiliary tank. The main fuel tank 21 Is connected to the auxiliary tank 30 by a fuel line 22 equipped with a metering pump 40. The metering pump 40 is a positive displacement pump and preferably a piston or a diaphragm metering pump and therefore has the advantage of delivering identical volumes of fuel per stroke regardless of the suction and discharge side pressures. Such piston and diaphragm metering pumps are known per se. A discharge non-return valve (not shown) oonnected to the auxiliary tank 30 via line 39 and a suction non-return valve (not shown) connected to the main fuel tank 21 via line 22. The metering pump may be of conventional construction and Is Illustrated only schematically. The piston pump 48 has a pump body and a piston shaft 46 connected to the piston per se. The piston le driven by a standard pump motor 42 via a geared coupling 43 and a reduction gear mechanism 44 which drives a cam 45 which ensures reciprocal movement of the piston shaft 46, as is conventional per se. Sensing means are associated with the metering pump for providing an output corresponding to the amount of fuel pumped by the metering pump in the given time period. In the illustrated embodiment, the pump discharge corresponds An embodiment of the fuel monitoring system for the motor vehicle diesel engine will now be described by way of example with reference to the accompanying drawings. Brief Description of the Drawings Fig. 1 is a schematic view of an embodiment of the fuel monitoring system for a motor vehicle diesel engine. Fig. 2 is a schematic view of the auxiliary tank and the metering pump for the embodiment of Fig. 1. Fig. 3 Is a schematic view of the fuel pump and control and sensing units therefor. Detailed Description of Embodiments ofth.fl Invention The present fuel monitoring system 20 for a motor vehicle diesel engine 10 may equip the vehicle as original equipment or for retrofitting existing vehicles and also when installed as permanent equipment of the vehicle. Fig. 1 shows part of both the original fuel supply line 11 (in dotted line) and the original fuel return line 12 (also In dotted line) connected between the main fuel tank 21 and the diesei engine 10 as Is known per se and will not be described. The original fuel supply line 11 for carrying fuel from the main tank 21 to the engine and the original fuel return line 12 for carrying fuel to be circulated to the main tank 21 as illustrated are disconnected and/or rerouted via lines 11' and 10' (shown In solid line) from the engine to an auxiliary tank 30. The auxiliary tank 30 preferably has the same cross section as the main tank 21. Also Ihe auxiliary tank Is preferably located so that the bottom of the auxiliary tank 30 and the bottom of the main tank 21 are at the same height over ground level. Accordingly, the engine draws fuel from the auxiliary tank 30 in the same condjtions after the connection of the engine to the auxiliary tank 30 via new fuel supply line 11" and the connection of the auxiliary tank to the engine via new fuel return line 12 as ft did when the main fuel tank was connected to the angina via the original fuel supply line and original fuel return line. The auxiliary tank 30 does not affect the fluid dynamics of the tuel delivery and return system. In the Illustrated embodiment the main tank 21 and the auxiliary tank 30 are cylindrical with their axes disposed horl2ontally. The axis of the preferably cylindrical auxiliary fuel tank 30 Is therefore in alignment with the axis of the main fuel tank 21 and their diameters equal. amount of fuel pumped in the given time period, and thereby the fuel consumption of the engine for the given time period. According to an embodiment of the invention, wherein the detector is a fuel detector mounted in the auxiliary tank for providing a signal to the metering pump when the amount of fuel In the auxiliary tank reaches a predetermined minimum value and/or a predetermined maximum value, so that the metering pump starts pumping fuel when the predetermined minimum value Is reached and stops pumping fuel when the predetermined maximum value is reached. According to an embodiment of the invention, the fuel detector is a fuel level detector and In particular a float switch. Other kinds of fuel detectors may be used which do not involve the detection of the fuel level but, for example, the weight of fuel. According to an embodiment, the auxiliary tank Is mounted on the vehicle at the same level as the main fuel tank and has the same cross section or cross section area as the main fuel tank. According to a second aspect of the invention, there is provided a method for monitoring fuel consumption in a motor vehicle diesel engine comprising providing an auxiliary fuel tank and connecting the auxiliary tank between the fuel supply line and the fuel return line of the diesel engine; providing a metering pump in a fuel line connected between the main tank and the auxiliary tank; detecting the quantity of fuel In the auxiliary tank; starting the metering pump when the fuel in the auxiliary tank reaches a first predetermined level and stopping the metering pump when the fuel in the auxiliary tank reaches a second predetermined level; determining the amount of fuel pumped by the pump over a given time period and thereby determining the fuel consumption by the engine over the given time period. Preferably, for either the first aspect or the second aspect of the invention, in order to avoid constantly monitoring the quantity of fuel in the auxiliary tank, with inherent consequential errors, the amount of fuel pumped by the metering pump Is determined at given Intervals corresponding to the starting and/or stopping of the metering pump and taking into account the quantity of fuel In the auxiliary tank at those given intervals, i.e. the minimum level or the maximum level. CLAIRE 1. A fuel monitoring system (20) for a motor vehicle dlesel engine (10) comprising an auxiliary fuel tank (30) adapted to be connected between the fuel supply line (11) and the fuel return line (12) of the dlesel engine, a detector for detecting the quantity of fuel In the auxiliary tank, a metering pump (40) adapted to be connected between said auxiliary tank (30) and the main fuel tank (21) of the motor vehicle for supplying metered quantities of fuel to the auxiliary tank in response to changes In the quantity of fuel in the auxiliary tank, sensing means associated with the fuel pump for providing an output corresponding to the amount of fuel pumped by the metering pump in a given time period and a computing unit (50) for determining the amount of metered fuel displaced by the metering pump in a given time period and thereby the fuel consumption of the engine for the given time period 2. A fuel monitoring system according to claim 1, wherein the is e fuel detector mounted in the auxiliary tank (30) for providing a signal to the metering pump (40) when the amount of fuel in the auxiliary tank (30) reaches a predetermined minimum value and/or a predetermined maximum value, so that the metering pump (40) starts pumping fuel when the predetermined minimum value is reached and stops pumping fuel when the predetermined maximum value is reached. 3. A fuel monitoring system according to claim 2, wherein the fuel detector is a fuel level detector. 4. A fuel monitoring system according to claim 2, wherein the fuel detector is a fuel level switch. 5. A fuel monitoring system according to any one of the preceding claims, wherein the auxiliary tank (30) has the same height and width as the main fuel tank (21). 6. A fuel monitoring system according to any one of the preceding claims, wherein the bottom of the auxiliary tank (30) is at the same level as the bottom of the main fuel tank (21). 7. A fuel monitoring system according to any one of the preceding claims wherein the,amounts of fuel pumped by the metering pump (40) are determined at given intervals corresponding to the starting and/or stopping of the metering pump (40). 8. A fuel monitoring system according to claim 7, wherein the fuel consumption corresponds to the amount of fuel pumped plus or minus the change of the quantity of fuel In the auxiliary tank (30).. 9. A motor vehicle diesal engine equipped with a fuel monitoring system according to any one of the preceding claims. 10. A method for monitoring fuel consumption in a motor vehicle dieeel engine comprising providing an auxiliary fuel tank and connecting the auxiliary tank between the fuel supply line and the fuel return line of the diesel engine; providing a metering pump In a fuel line connected between the main tank and the auxiliary tank; detecting the quantity of fuel In the auxiliary tank; starting the metering pump when the fuel in the auxiliary tank reaches a first predetermined level and stopping the metering pump when the fuel in the auxiliary tank reaches a second predetermined level; determining the amount of fuel displaced by the pump over a given time period and thereby determining the fuel consumption by the engine over the given time period. 11. A method for monitoring fuel consumption in a motor vehicle diesel engine, according to claim 10, wherein changes In the amount of fuel in the auxiliary tank (30) are taken Into consideration when determining the fuel consumption based on the amount of fuel displaced by the pump. 11 A method for monitoring fuel consumption In a motor vehicle diesel engine according to claim 10, comprising determining the amounts of fuel pumped by the metering pump at given Intervale corresponding to the starting and/or stopping of the metering pump. 12. A method for monitoring fuel consumption in a motor vehicle diesel engine according to claim 10 or claim 11 wherein the fuel consumption corresponds to the amount of fuel pumped plus or minus the change of the quantity of fuel in the auxiliary tank. 13. A method for monitoring fuel consumption in a motor vehicle diesel engine according to any one of the preceding claims, wherein the fuel consumption is displayed In the vehicle. 14. A method for monitoring fuel consumption In a motor vehicle diese! engine according to any one of the preceding claims, wherein the fuel consumption is transmitted to a remote or control centre for controlling fuel consumption of a fleet of vehicles.

Documents:

0709-che-2005-abstract.pdf

0709-che-2005-claims.pdf

0709-che-2005-correspondnece-others.pdf

0709-che-2005-description(complete).pdf

0709-che-2005-drawings.pdf

0709-che-2005-form 1.pdf

0709-che-2005-form 3.pdf

709-CHE-2005 AMENDED PAGES OF SPECIFICATION 02-01-2014.pdf

709-CHE-2005 AMENDED CLAIMS 02-01-2014.pdf

709-CHE-2005 CORRESPONDENCE OTHERS 08-03-2013.pdf

709-CHE-2005 EXAMINATION REPORT REPLY RECEIVED 02-01-2014.pdf

709-CHE-2005 FORM-1 02-01-2014.pdf

709-CHE-2005 FORM-13 02-01-2014.pdf

709-CHE-2005 FORM-13-1 02-01-2014.pdf

709-CHE-2005 FORM-3 02-01-2014.pdf

709-CHE-2005 POWER OF ATTORNEY 02-01-2014.pdf

709-CHE-2005 OTHER PATENT DOCUMENT 02-01-2014.pdf