FR2873752A1 - Common rail type dual fuel supply device for diesel engine, has solenoid valve for selecting fuel that directly arrives at feed pump of injection pump, and electronic case connected to tachograph that sends information about vehicle speed - Google Patents

Abstract

The device has a three-way solenoid valve (4) for selecting fuel that then directly arrives at a feed pump of a high pressure injection pump (9). The pump (9) sends the fuel towards a common injection harness (10), which then supplies high pressure injectors (12) that are connected to another three-way solenoid valve (22). An electronic case is connected to a tachograph that sends information about speed of a vehicle.

Description

2873752 1

  DUAL FUEL FEED DEVICE

FOR DIESEL ENGINE

  The invention relates to a device for supplying diesel engines with domestic fuel.

  Such a power supply is used, for example, for self-propelled cranes, self-propelled concrete pumps, concrete mixer trucks (concrete tops), bucket trucks, water-tanker tankers.

  In France, the Ministerial Decree of 29 April 1970 (Official Gazette Laws and Decrees of 10 May 1970, page 4419) set conditions for the use of fuel oil to benefit from the privileged tax regime established by Article 265 of the Customs Code. as regards the internal consumption tax. According to Article 1 of this Decree, special vehicles, such as concrete mixers, with a single engine alternately providing propulsion for the vehicle and the operation of the equipment mounted on it, may use fuel for these appliances, subject to the presence of a double fuel tank and an automatic selection device preventing, during the propulsion of the vehicle, the supply of the single engine from the fuel tank.

  Domestic fuel, much less taxed than diesel in France, must contain a scarlet red dye such as azobetanaphthol and a tracer agent called Solvent Yellow 124, these regulations facilitate the detection of prohibited uses of heating oil.

  Various designs of dual fuel systems for diesel engines are already known in the prior art.

  Document FR-2.220.679 describes a plant for controlling the supply of a diesel engine injection pump, selectively from a fuel tank or a fuel tank. This installation comprises two three-way solenoid valves controlled by the manual control of the clutch of the engine, the first directly and the second via a timed relay.

  2873752 2 The operation of this prior installation is as follows. When the motor of the concrete pump is coupled to this concrete pump, the clutch lever is in a position referenced 2C and the fuel contained in a tank passes into the three-way supply solenoid valve to supply the injection pump of the motor. The output of the injection pump is connected to the three-way return solenoid valve, itself connected to the two fuel tanks. When the engine of the concrete pump is coupled to the wheels of the vehicle, the clutch lever is in a position referenced 2R and the fuel oil is pumped from its tank to pass into the supply solenoid valve, the injection pump and the engine. Return solenoid valve.

  The device described in FR-2.220.679 has many disadvantages. In particular, both fuels use identical circuits (piping and solenoid valves) and a single engine supply pump runs continuously. This device therefore requires modifying the engine mounting of the manufacturer, with risks in terms of warranty, safety, especially with respect to overpressure and heating of fuels.

  Document FR-2,296,766 describes an automatic fuel selection device for a diesel engine. This device is particularly complex and comprises no less than five pneumatic distributors. A single injection pump supplies the engine with diesel and fuel oil, which requires modifying the manufacturer's engine assembly, with risks in terms of guarantee and safety, particularly with respect to overpressures and heating of fuels.

  Document FR-2,474,590 briefly describes a device for raising the quantities of fuel used at the time of filling the two fuel tanks and domestic fuel. A fuel change solenoid valve is connected to both tanks and sends the selected fuel to the booster pump of the engine. The return of the injectors is returned to the domestic fuel tank and the return of the injection pump is conducted upstream of the booster pump.

  Reference may also be made to documents FR-2,483,525 and FR-2. 510,660, FR-2,797,470, US-4,620,568.

  Most of the previously known systems for feeding domestic diesel engines with return are not completely independent of the original fuel system, which can lead to overpressure, overheating of the fuel and damage to the injection system and the filters. , while modifying the manufacturers' settings, so that the manufacturers suspend their guarantee as soon as an anomaly occurs.

  Previously known systems are not, moreover, compatible with modern common rail injection techniques.

  The power management of diesel engines is complex. To ensure proper preparation of the fuel / air mixture, the fuel must be injected into the combustion chamber at a pressure between 350 and 2000 bar. For a compromise between low consumption and compliance with the emission limit values (exhaust gas and noise), the start of injection must be accurate to plus or minus a degree of crankshaft angle.

  The so-called common rail fuel injection systems make it possible to generate the injection pressure independently of the speed and the load. The injection pressure is generated by a separate high pressure pump which does not have to operate in synchronism with the injections. The injectors are electronically controlled. In this common rail system, the dispersion between the rolls must be low and the injection system consists of very high precision components. The injection process is initiated by an electronic computer that transmits at the right moment a control pulse to the solenoid valve of the injector. The pressure level frequently exceeds 1400 bar.

  The complexity of common rail type diesel injection systems does not permit the use of a dual fuel delivery device known in the prior art.

  The invention aims in particular to overcome the drawbacks mentioned of dual feed devices for diesel engines known previously.

  The invention aims in particular to provide a bi-fuel device which is completely autonomous and anti-fraud, this device being compatible with the pressures and feed rates of modern diesel engines (of the order of 1200 liters per hour at 25 ° C). bars, and 1600 bar injection), without modifying the performance of these engines, nor increase the pollution levels and the temperature of the supply circuits.

  For these purposes, the invention relates, according to a first aspect, to a device for supplying a common rail engine with domestic fuel or diesel fuel, from separate fuel oil and diesel fuel tanks. domestic fuel being completely independent of the fuel system, characterized in that it comprises, in combination, a three-way solenoid valve for fuel selection, a three-way solenoid valve for fuel return, the fuel selected by the actuation of the solenoid valve of selection of fuel arriving directly to the feed pump of the high-pressure injection pump of the engine, the return solenoid valve being connected to the outlet of the injectors and the common injection rail.

  The feed device has the following characters, possibly combined: it comprises a fuel filtration circuit, connected to the feed pump of the high-pressure injection pump, this circuit comprising a three-way solenoid valve, a gas oil filter, a fuel filter and two non-return valves; the fuel supply circuit comprises a non-return valve upstream of the fuel selection solenoid valve; the fuel supply circuit comprises a non-return valve upstream of the fuel selection solenoid valve; the return solenoid valve placed on the common fuel return circuit allows, by its timed control, the rinsing of the high-pressure injection pump as soon as the diesel engine is restarted; 2873752 5 its operation is automatically switched on when pressure switches on the parking brake system, gearbox and power take-off are engaged; an indicator lights up on the dashboard of the vehicle when the engine is fueled with fuel, a transparent cup being further integrated in the fuel return circuit, downstream of the return solenoid valve, so as to visually check the type fuel used.

  Other objects and advantages of the invention will become apparent from the following description of embodiments, which description will be made with reference to the appended single drawing which is a block diagram of a device according to a particular embodiment. of the invention.

  In this figure are diagrammatically the tanks of domestic fuel 1 and gas oil 2.

  A first conduit 3 brings the fuel contained in the tank 1 to a first three-way solenoid valve 4, feed selection.

  A first non-return valve 5 is placed on the first duct 3 between the tank 1 and the first solenoid valve 4.

  A second duct 6 brings the gasoil contained in the tank 2 to the first solenoid of feed selection 4.

  A second non-return valve 7 is placed on this second duct 6, between the tank 2 and the first solenoid valve 4.

  A third conduit 8 connects the first feed selection solenoid valve 4 to the feed pump of the high pressure injection pump 9 of the common rail type diesel engine.

  This high-pressure injection pump 9 sends the fuel to the common injection rail 10 via a fourth duct 11.

  This injection ramp 10 supplies the high-pressure injectors 12.

  The device comprises a filtration circuit connected to the feed pump of the high-pressure injection pump 9.

  In this filtration circuit, a fifth duct 13 brings the fuel to a second separation and filtration solenoid valve 14, this second three-way solenoid valve 14 being connected to a gas oil filter 15 and a fuel filter 16. The two filters 15, 16 are connected to the feed pump of the high-pressure injection pump, for return after filtration, via a sixth and a seventh conduit 17, 18, each of these conduits 17, 18 comprising a non-return valve 19, 20 .

  The fuel return circuit is as follows.

  A main return duct 21 connects the common rail outlet 10 and the injectors 12 respectively to the high pressure injection pump 9 and the third three-way solenoid valve, return management 22.

  This third solenoid valve 22 sends the fuel to respectively the fuel tank 1 and the fuel tank 2, a transparent cup 23 being placed on the conduit 24 connecting this third solenoid valve 22 to the fuel tank 1.

  This transparent cup 23 allows the customs control, the domestic fuel containing a scarlet red dye such as azobetanaphthol, and a tracer agent called Solvent Yellow 124.

  The device that has just been described has many advantages.

  The domestic fuel pump can be of the same capacity as that of the engine manufacturer or, for very large flows, the original pump.

  The device works with fuel returns, unlike most existing aircraft currently on the market, so a Euro engine remains Euro.

  The device is put into operation as follows: a key installed on the dashboard controls the activation of the solenoid valves, the supply pump sucking the domestic fuel oil instead of the diesel fuel and routing it into the corresponding filter .

  The return solenoid valve 22 activated also ensures the delivery of the overflow to the fuel tank 1.

  If the fuel supply is performed by an additional electric pump or the like, this pump starts and sends the domestic fuel 2873752 7 to its filter, the solenoid valve simultaneously deflecting the fuel to its reservoir, the return solenoid valve 22 being delayed and remaining open the time required for flushing the injection manifold 10 or the injection pump 9, this flushing being fast, of the order of 15 to 30 seconds for most commercial truck engines .

  In one embodiment, the flushing is automatic and controlled by the electronic box of the device, the box connected to the controller.

  The return to the fuel supply to the diesel engine is done automatically as soon as the vehicle resumes the road, without particular handling of the driver, a slow speed of the order of 10 kilometers per hour remaining possible with an oil fuel operation.

  An electronic unit is set, in an advantageous embodiment, once and for all for mounting on the vehicle, for the automatic management of all the functions of the dual power device, including its stop.

  This electronic box is connected to the controller who sends him information on the speed of the vehicle. Thus, as soon as the speed exceeds a so-called slow speed threshold (10 km per hour for example) the dual feed device automatically controls the return of diesel fuel from the vehicle engine. This arrangement avoids the fraud consisting in the use of domestic fuel for the supply of the vehicle in road trip.

  When the vehicle engine is running on fuel oil, it is possible to release the parking brake for a slow speed drive.

Claims (1)

8 claims   1. Device for supplying a common rail engine with domestic fuel or diesel oil, from separate fuel oil and diesel fuel tanks, the domestic fuel supply circuit being completely independent of the fuel system, characterized in that comprises, in combination, a three-way solenoid valve (4) for fuel selection, a three-way solenoid valve (22) for fuel return, the fuel selected by the actuation of the fuel selector solenoid valve (4) arriving directly at the feed pump of the high-pressure injection pump (9) of the engine, the return solenoid valve (22) being connected to the outlet of the injectors (12) and the common injection manifold (10).   2. Feeding device according to claim 1, characterized in that it comprises a fuel filtration circuit, connected to the feed pump of the high-pressure injection pump (9), this circuit comprising a solenoid valve three. channels (14), a gas oil filter (15), a fuel filter (16) and two non-return valves (18, 19).   3. Feeding device according to claim 1 or 2, characterized in that the fuel supply circuit comprises a non-return valve (5) upstream of the fuel selection solenoid valve (4).   4. Feeding device according to any one of claims 1 to 3, characterized in that the fuel supply circuit comprises a non-return valve (7) upstream of the fuel selection solenoid valve (4).   5. Supply device according to any one of the preceding claims, characterized in that the return solenoid valve (22) placed on the common fuel return circuit allows, by its delayed control, the 2873752 9 rinsing pump of high pressure injection (9) as soon as the diesel engine is restarted.   6. Feeding device according to any one of the preceding claims, characterized in that its operation is automatically switched on as soon as pressure switches placed on the parking brake circuit, gearbox and power take-off are engaged.   7. Feeding device according to any one of the preceding claims, characterized in that a warning light on the dashboard of the vehicle when the engine is fueled with fuel, a transparent bucket (23) being further integrated into the fuel return circuit, downstream of the return solenoid valve (22), so as to visually check the type of fuel used.