WO2008028609A1

WO2008028609A1 - Method and device for feeding fuel

Info

Publication number: WO2008028609A1
Application number: PCT/EP2007/007670
Authority: WO
Inventors: Karlheinrich Winkelmann
Original assignee: SCHÄCKEL, André
Priority date: 2006-09-05
Filing date: 2007-09-03
Publication date: 2008-03-13
Also published as: DE102006042054A1

Abstract

Proposed is a method and a device, which method utilizes the double character of liquid gas, unique among the conventional fuels for internal combustion engines, of being usable both as a fuel for an internal combustion engine and also as refrigerant in a cooling circuit, simultaneously in a single coupled system. By coupling the fuel supply to the injection valves to the suitable point of the air-conditioning circuit, a part of the air-conditioning circuit is simultaneously utilized as a supply group for the fuel injection. Evaporators in the air-conditioning circuit are simultaneously used not only for the air-conditioning of the interior space, for example of a motor vehicle, but rather also for cooling the combustion air supplied to the internal combustion engine to below the freezing point of water. In this way, the thermodynamic efficiency of the combustion process is improved far beyond the limits of that which could previously be obtained in spark-ignition engines.

Description

Method and device for transporting fuel

Technical area

The invention relates to a method according to the preamble in claim 1 and an apparatus according to claim 10.

State of the art

Gasoline engines, which supply the fuel liquid gas indirectly to the combustion chamber via the intake line of the combustion air, mainly use the evaporation process to bring the liquefied gas into the supply channel for the combustion air. In this case, the liquefied gas is forced out of the tank by its own vapor pressure into a cooling-water-heated evaporator in which it is completely transferred from the mixing phase into the gas phase. From the evaporator, the gaseous liquefied gas is supplied under pressure to its own distribution bar, from which each cylinder, computer-controlled via clocked solenoid valves, the appropriate amount of gaseous fuel is injected into the incoming combustion air for each combustion cycle. These systems can only be operated bivalent, because they need in addition to the liquid gas to start the internal combustion engine another fuel, preferably gasoline. Only when the internal combustion engine delivers sufficient heat for the evaporator can this be switched to operation with LPG. There are also injection systems which liquidly guide the liquefied gas via a pump in the liquefied gas tank to the injection valves for the liquefied gas and liquid inject the liquefied gas into the supply passage for the combustion air before the intake valves. In the literature, as in US 5 857 448 A, EP 1 010 886 A, DE 196 11381 A, patent Abstracts of Japan JP 2001 349256 A ₁ DE 201 01 475 U, DE 101 46 051, Injection systems are described, which also supply via an in-tank fuel delivery unit and usually also via another, lying outside the liquefied gas tank, device for increasing the pressure, the liquefied gas an injector. Common to all the systems mentioned is that they have the special property of the fuel liquefied gas in a temperature-pressure range from the liquid to the gaseous state, which can be controlled technically relatively simple and thereby develop a cooling effect by its evaporative cooling, either not or, in the case of the evaporator mentioned above, without additional profit.

In DE 201 01 672.9 it is proposed to activate the on-board air conditioning system via a knock sensor or a temperature probe in the exhaust duct when a temperature limit is exceeded. The air conditioner supplies coolant to an evaporator through which the intake air flows. To prevent the formation of ice, the on-board air conditioning system limits the cooling temperature to approx. 5 ⁰ C. This configuration allows cooling only up to this temperature. Furthermore, the system works with conventional refrigerants and not with LPG, so it does not use the dual character of fuel and cooling medium. The object of the present invention is to render the fuel supply process thermally more stable and the thermodynamic cycle thermodynamically more efficient.

The Invention These problems are solved by the method described in claim 1. Advantageous variants can be found in the dependent claims.

The present method has advantages at several levels. It saves components, makes the fuel supply of the fuel LPG ther- more robust and increases the efficiency of the thermodynamic cycle.

Neither a fuel evaporator nor a fuel pump in the liquefied gas tank is required because the air conditioning compressor gaseously aspirates the liquefied gas, which is both fuel and refrigerant in the process described herein. As a result, the fuel supply system gains thermal stability. Especially in systems with liquid injection of liquefied gas, any heat input into the fuel on its way from the LPG tank to the injectors had to be compensated for by increased pressure or additional cooling, while at this point in the refrigeration cycle additional warming is welcome as it is the gas phase of the LPG Stabilizes fuel and ensures that the compressor is supplied only liquid gas in the gas phase.

The majority of motor vehicles that are new on the market, is now equipped with air conditioning. Thus, the condition is given to establish a refrigerant circuit with the fuel LPG as the refrigerant without substantial cost in place of the refrigeration cycle with the usual refrigerant R134a. What is essential is the possible gain in thermodynamic efficiency which the cooling of the intake air brings about by the cooling effect of the liquefied gas evaporating in the refrigeration cycle. Calculations show that reducing the initial temperature in the thermodynamic cycle of combustion increases the efficiency of the process three times compared to increasing the final temperature by the same amount of temperature. The refrigeration cycle of the liquefied gas now allows cooling of the combustion air below the ambient temperature and below the freezing point of the water. This makes it possible to increase the compression of the internal combustion engine significantly without exceeding the auto-ignition temperature of the fuel LPG. As a result, can be in the gasoline engine compression ratios that do not limit their 90 more, as at present, by reaching the autoignition temperature of the fuel, but in the mechanical and thermal capacity of the material. As a result, it is possible to realize thermodynamic efficiencies which are equivalent to the efficiency of the diesel process or even surpass it and go far beyond the limits of what was previously achievable with petrol engines. This in turn means that torque and power increase significantly, while at the same time significantly reducing specific fuel consumption and, in parallel, the CO2 emissions of the combustion process. According to an advantageous variant of the method, it is provided that

100 down the fuel tank there is a device in which incoming, not yet vaporized, liquid liquid refrigerant portions are completely evaporated before entering the air-fuel compressor. Furthermore, it is provided in an advantageous variant of the method that a dosing device by the combustion process the cooling force

105 extracted compressor lubricant.

Brief description of the drawings

Embodiments of the method are shown schematically in Figures 1 and 2. Figure 1 forms a fuel-cooling system with direct injection of

FIG. 2 shows a fuel-cooling system with injection of the fuel into the intake passage of the gasoline engine, with FIG. 2 essentially differing from FIG. 1 by the omission of the high-pressure fuel pump. For this reason, FIG. 1 will be described in greater detail below.

It shows the figure 1 is a schematically illustrated fuel-cooling system whose components fuel tank, device for fuel heating, compressor, condenser, high-pressure fuel pump, expansion valve of the refrigeration cycle, two parallel evaporators connected by fuel lines are connected to a circuit. It shows a diversion from 120 fuel in the high-pressure fuel pump which leads to the fuel rail with the injection valves of a (not shown here) gasoline engine, where the fuel is injected directly into the combustion chamber.

Figure 1 also shows schematically the connection of an air conditioning circuit with which, for example, the cabin of a motor vehicle can be air-conditioned.

125 Not shown is a possible variant, which branches off the fuel in front of the condenser of the refrigeration cycle in the gas phase and feeds him inflation valves in gaseous form.

Best way to carry out the invention

130 The compressor 2 of the fuel-cooling circuit sucks in gaseous liquefied petroleum gas and compresses it. In a preferred embodiment, it is driven independently of the internal combustion engine, preferably electrically. This has the advantage that the compressor 2 can start even before the engine starts and thereby the fuel supply system (7 - 11) when starting

135 of the engine liquid fuel is available. This is necessary if a pressure equalization takes place at a standstill via the cooling circuit, so that no fuel would be available in the liquid phase to the fuel injection system without compressor advance at the start of the engine. Before the liquid gas 3 enters the compressor 2, it first flows through the

140 device for re-evaporation of the liquefied gas 5, which, if necessary, by additionally heating the liquefied gas ensures that even at full load flow rate, no liquefied gas in the liquid state of matter enters the compressor 2. Subsequently, should the necessity arise in the practical testing, the LPG for lubrication of the compressor 2

145 to admix a lubricant, which admixed the liquid gas extracted by the combustion compressor super lubricants by a metering device 15 to the fuel-air conditioning system again. The compressor 2 then presses the compressed liquid gas 3 via the line 7 to the condenser 6, where the, heated by the compression, liquefied gas 3 is cooled and 150 liquefies. After the condenser 6, the fuel line branches 7. In the case of high-pressure direct injection of the fuel required for combustion of the high-pressure fuel pump 8 is again set under increased pressure and passes through a high pressure line 9 to the fuel rail 10, from where the fuel via injectors 11 in the (here

155 not shown) combustion chamber of the internal combustion engine is injected.

The non-branched for the combustion, excess liquid fuel flows through the low pressure region of the high-pressure fuel pump and remains in the refrigeration cycle and passes through the expansion valve 17, where he

160 is evaporated.

The one branch 19 supplies a heat exchanger 20, through which a heat transfer medium, preferably a water-antifreeze mixture flows, which receives the cold of the evaporating liquefied gas, from where it to another

165 heat exchanger 22 is pumped inside the cabin by a circulation pump 23. By suitable coupling to the heating circuit, the desired temperature can then be adjusted by mixing the heat transfer media. The other strand 24 leads to two evaporators 25,26 that of the coolant

170 are flowed through in parallel but successively from the combustion air 27. In this case, the combustion air temperature of the evaporator 25, which is first passed through by the combustion air, is regulated in such a way that it precipitates the moisture contained in it and is discharged downwards in liquid form 28. In the following evaporator 26, the dry combustion

175 29 until the freezing point continues to cool. From the evaporators 25, 26, a refrigerant line 30 continues downstream in the direction of the compressor 2 after the refrigerant line 19 of the heat exchanger has previously been added. At a suitable location between the expansion valve 17 and the evaporators 180, the fuel tank 1 is connected by a line 12. From the fuel tank 1, the fuel consumed in the combustion process is supplemented via an expansion valve 16, whereby it evaporates to cool the combustion air 27.

185

List of reference numbers

1 liquefied gas tank

2 compressor

190 3 Liquefied Petroleum Gas (LPG) in the gas phase

4 liquefied petroleum gas (LPG) in the liquid phase

5 Device for re-evaporation of the liquefied gas

6 capacitor

7 Fuel Refrigerant Line 195 8 High-pressure fuel pump

9 high-pressure fuel line

10 fuel rail

11 injectors

12 Fuel line 00 13 Check valve

14 storage and expansion vessel

15 lubricant metering device

16 expansion valve

17 Expansion valve 05 18 Refrigerant line

19 Refrigerant line

20 heat exchangers

21 heat transfer medium 22 Heat exchanger interior 23 Circulation pump

24 fuel refrigerant line

25 evaporator stage 1

26 evaporator stage 2

27 Combustion air humid 28 Condensate drain

29 combustion air dry

30 fuel refrigerant line

Claims

Patentansprüche240

Method for conveying fuel, in particular liquefied petroleum gas (3) or one of its components or a mixture of its components from a fuel tank (1) into the fuel supply system (7-11)

245 of an internal combustion engine characterized in that at ai suitable place in the fuel supply system (7 -11) a

Part of the fuel as a refrigerant for cooling the combustion air (27) is diverted. 250

2. The method according to claim 1, characterized in that the refrigerant remaining in the circuit as a fuel quantity is evaporated and the cold generated thereby is transmitted to the combustion air of the engine.

255

3. The method according to claim 1, characterized in that the branched off for combustion in the internal combustion engine amount of fuel (3) in the case of port injection the fuel injection system (10,11) directly, in the case of direct injection via a Hochdruckkraft-

260 fuel pump (8) is supplied, in particular the excess

Fuel quantity is passed through the low pressure part of the high-pressure fuel pump (8).

4. Method according to one of the preceding claims characterized in that a fuel supply in the liquid state of aggregation (4) is available for starting the internal combustion engine, which is stored in a supply and expansion vessel (14), which fuel supply (4) is prevented by at least one valve (13) from the fuel supply system back into the cooling circuit.

5. The method according to claim 3, characterized in that, alternatively or in addition to the fuel supply in the liquid state (4), a compressor (2) by forward flow before the start of Verbrennungskraftma- 275 the necessary fuel for combustion in the liquid phase (4) ,

6. The method according to any one of the preceding claims, characterized in that the cooling of the combustion air (27) takes place in at least two 280 stages when the combustion air (27) is to be cooled below the freezing point of the water vapor contained therein, wherein the temperature of the first cooling stage (25) is limited by a control or regulation so that the steam contained in the combustion air (27) as condensation water and not as ice 285 deposited.

7. The method according to any one of the preceding claims, characterized in that the circuit for the air conditioning of an interior space (22,23) is supplied by the fuel-cooling circuit with cold, pre 290 preferably via a heat exchanger (20,21).

8. The method according to any one of the preceding claims, characterized in that the fuel rail (10) flowing fuel is additionally cooled, in the case of direct high-pressure injection before entering 295, the high-pressure fuel pump (8).

9. A method of transporting fuel, in particular according to one of the preceding claims, characterized in that, for the force generated fuel combustion at a suitable location of the refrigeration circuit is supplemented from the fuel tank (1), contributes to cooling by evaporation, to be subsequently sucked, compressed and liquefied transported by cooling in the fuel supply system.

10. A device for carrying out a method according to one of the preceding claims with a fuel supply system and a cooling device for cooling the combustion air, characterized in that the Krεftstoffzuführungssystem has a branch (18) which connects the fuel supply system with the refrigeration device, so

310 that a portion of the fuel is passed through the refrigeration device and that the fuel tank (1) is connected by a conduit (12) to the refrigeration device, so that the supplemental fuel is passed through the refrigeration device.

315

320

325