DE102008024561A1 - Method for operating internal combustion engine, involves detecting induced signal through electrical load, and starting fuel circulation in low-pressure fuel circuit in response to detected signal - Google Patents

Abstract

The method involves detecting an induced signal through an electrical load, and starting a fuel circulation in a low-pressure fuel circuit in response to the detected signal, where the signal is applied as start pulse for the starting of the fuel circulation. A petrol engine is applied as internal combustion engine. An independent claim is included for an internal combustion engine, which comprises a low-pressure fuel circuit.

Description

The The invention relates to a method for operating an internal combustion engine according to the preamble of claim 1 and an internal combustion engine according to the preamble of claim 12.

Petrol engines Be after the state of the art for the operation with the Fuel gasoline designed. Accordingly, the control and Control strategies of the engine management of the engine control unit and the maps used by him on the physical properties of gasoline fuel, in particular on its vaporization characteristics.

The Evaporation characteristic of the fuel gasoline is different but significantly from the evaporation characteristics of the fuel LPG. While gasoline has a boiling range of 25 ° C-210 ° C and its vapor pressure in operation is about 0.5 bar, the boiling point of LPG is at one Pressure of 1013 mbar -30 ° C (Applies to LPG fuel consisting of 60% propane and 40% butane) and the vapor pressure approximately 6 bar.

Out this difference in fuel vaporisation characteristics during operation of an Otto engine with the fuel LPG in liquid phase specific problems, especially at the start of the engine both in Cold (cold start) and warm operating condition (warm start).

injection injecting the LPG in liquid phase in principle the problem is that the operating pressure at each point in the fuel flow the fuel supply system from the fuel tank to the Fuel injection valves above the evaporation pressure the LPG used must be so that the internal combustion engine can work smoothly. This ensures in known Injection systems inject the LPG into liquid phase one electrically driven fuel pump in LPG tank in combination with a pressure regulator in the fuel return line. Ensures fuel vapor pressure compensation of the pressure regulator that the changing evaporation pressures result in different Fuel temperatures of the LPG in the LPG tank not by one of the fuel pump to be generated, overpressure compensated Need to become. The fuel evaporation pressure compensation the pressure regulator does not compensate for the local evaporation pressure increase, by warming the LPG on its way from the LPG tank to the injectors swell by heat from heat, such as winding the fuel pump, solenoid valve of the shut-off device on the LPG tank, heat conduction from the warm engine and the air heated by it in the engine compartment, fuel compression in the high-pressure pump, solenoid valves to lock the fuels against each other in bivalent operation, sets. When the engine is running this problem by a continuous, cooling Fuel circulation in the fuel supply system and through the cooling Fuel flow through the fuel injectors solved.

Known Systems containing LPG in liquid phase in the intake duct inject a gasoline engine, have a lower heat input in the LPG as systems, the LPG in liquid phase directly inject into the combustion chamber. Therefore, they are sufficient in this Operating state normally a permanent overpressure from 3-5 bar to the evaporation pressure increasing Heat input on the way of the LPG in liquid phase from the tank to the injectors so buffer the LPG in Liquid phase remains. However, this also stays with this one Configuring the residual risk that with prolonged uninterrupted engine operation and a resulting low Tank contents in the LPG tank, the LPG in the LPG tank heats up so much that its evaporation pressure is higher than the pressure, the a pump is generated on an LPG fuel pump, so that a Refueling of LPG possible after a cooling phase is.

Direct injection systems, as used in the DE 101 46 051 are described, inject the LPG in liquid phase into the combustion chamber of the gasoline engine through the high-pressure fuel pump and the solenoid valves that control the switching of the fuel types, an additional, higher heat input into the fuel. In the DE 101 46 051 Therefore, a fuel supply system for LPG is described, which has in the fuel supply line connected to an air conditioning fuel cooling device. This configuration controls all heat input into the LPG while the engine is running.

Not dominated by the in the DE 101 46 051 the rapid warm start described after prolonged shutdown of a warm engine when components of the fuel supply system, here in particular the high-pressure fuel pump, have heated up strongly. The cause is the heat flowing from the engine block into the components, which is no longer dissipated by the fuel circulated in the low-pressure fuel circuit or injected into the combustion chamber of the gasoline engine. Then, when the engine is restarted, the engine's failure may fail because there is no liquid fuel available because it has temporarily evaporated and its vapor pressure is higher than the fuel positive pressure generated by the fuel feed pump in the LPG tank.

Otto engines, which are operated with gas, a short lead is sufficient the gasoline pump before the engine start with a short-term increase the fuel pressure around fuel bubbles in the low pressure fuel delivery system, which may have been caused by heating, to eliminate. This gasoline pump flow is used in motor vehicles z. B. by opening the driver's door started.

Otto engines, which inject LPG into liquid phase as fuel the problem that the LPG in the course of this warming process within the components of the injection system from the liquid phase go into the vapor phase. Will these fuel vapor bubbles is not eliminated in the injection system before starting the engine is the engine is not bootable.

One Start with LPG with warm engine without fuel cooling Measures would be with petrol engines, meanwhile exclusively with "top-fed" injection valves inject liquid and intermittent into the intake channel (Channel injection) and in the latest generation increasingly without Fuel return from the fuel rail into the fuel tank manage to realize only with a very high fuel pump pressure.

These Problems with starting the engine with LPG are in known systems bypassed the gasoline engine with two complete fuel supply systems, usually with the fuels gasoline and LPG in liquid phase, is operated, the LPG system with "bottom-fed" injectors and a fuel return into the LPG fuel tank working and the possibility exists between the fuels, to switch back and forth. These engines are usually too started in LPG operating mode with gasoline. After successful engine start Switches the control of the motor after a more or less long Warm-up phase from the fuel gasoline to the LPG fuel.

In the EP 1 095 214 B1 a fuel system for port injection of LPG is described, which operates with variable pump pressures between 8 bar and 4 bar, with the temperature of the LPG in the fuel tank, the pump pressure of 8 bar to 4 bar, when the pressure in the LPG tank to 25 bar increases. For an injection system which injects LPG with "bottom-fed" injection valves into the intake channel, these pump pressures are sufficient to suppress gas bubble formation even during the warm start, because here only, as in the DE 103 60 977 mentioned, temperature differences of about 12-16 ° C are to be suppressed, for which pressures above 4 bar certainly meet. The disadvantage here, however, the high pressure must be permanently generated by the in-tank pump in the LPG tank, resulting in increased pump wear, increased heat input into the fuel and increased fuel consumption.

In the DE 103 60 977 A1 is proposed for a gasoline engine with port injection of LPG in liquid phase, to delay the engine start for predetermined periods of time, when a predetermined fuel temperature in the fuel line is not exceeded, while the fuel pump in the LPG tank pumped until shortly after engine start with maximum power. The period of interest is given as 15 to 30 seconds. This solution requires "bottom-fed" injectors and fuel return into the tank. Otherwise, it would have to operate with such high pressure of the in-tank pump in the LPG tank that would make the waiting time unnecessary.

In gasoline engines inject the LPG directly, although the high-pressure fuel range due to the prevailing high pressures vapor-critical, but are sufficient in the low pressure range of the high-pressure fuel-high-pressure pump also in the EP 1 095 214 B1 high pressures of 8 bar for prefeed pumps in the fuel tank, to the hot phase of the vapor bubbles, which can be due to the temperatures of about 70 ° C, which can heat up the high-pressure pump housing at a standstill after a long period of operation form, in the liquid phase due.

In the EP 06 023 298.0 is described by the author of the application that in gasoline engines with direct fuel injection operation with LPG in liquid phase with a warm engine, depending on the design of the high-pressure fuel pump, with reasonable technical effort is only possible if a low pressure fuel return line, preferably by an additional adapter or an additional Bore, is connected to the low pressure region of the high-pressure fuel pump that a low-pressure fuel circuit is formed, which flows well around the input to the high-pressure pumping chamber of the high-pressure fuel pump as a thermal critical point of the LPG fuel supply system, regardless of the amount of the fuel branched off for combustion.

One Warm start without unacceptable time delay by is the cooling process of the high-pressure fuel pump However, not only with this configuration, not all types the high-pressure fuel pump ensures. As unacceptable Here a period is defined as greater than 30 s is. The period of 30 s was in trials as the period determined by the operation of the radio unlocking is normally needed until the engine is started, provided the seatbelts are put on before the engine is started.

Under the number 3231881 was a patent for fuel cooling filed in which is proposed, especially in diesel internal combustion engines a fuel flowing through the heat exchanger in the coolant circuit to integrate a vehicle air conditioning system. Fuel cooling is in, representing the prior art, gasoline engines usually not needed with fuel injection and applied, as well with port injection of Otto engines in bivalent operation with the fuels gasoline and LPG.

Of the The invention is based on the problem of a method for operating an internal combustion engine and a correspondingly working internal combustion engine to create those with the mentioned disadvantages when starting the engine be avoided.

This Problem is solved by a method having the features of the claim 1 and an internal combustion engine having the features of the claim 12 solved. Find advantageous embodiments in the subclaims.

According to the invention before starting the engine first via a electronic control unit detects a signal which is on a Battery voltage drop is due to Example by pressing a remote control. This Signal becomes a start pulse for the start of a fuel circulation used. As a result, in particular during warm start a cooling of the fuel to be ignited before starting the engine reached.

• – die Direkteinspritzung von LPG möglich wird, die sonst an Platzgründen und auch aus Kostengründen scheitern würde,
• – die Vorhaltung eines zweiten Kraftstoffzuführungssystems für die Zuführung eines Normaldruck-Ottokraftstoffes, einschließlich des geschlossenen Kraftstoffsystems, das das Austreten von Kraftstoffdämpfen aus dem Kraftstofftank verhindert, aus technischen Gründen überflüssig wird,
• – ein Betrieb eines Otto-Motors ausschließlich mit LPG möglich ist,
• – kein teurer Normaldruck-Ottokraftstoff, vorzugsweise Benzin, zum Starten des Motors mehr benötigt wird, was besonders beim Einsatz von Start-Stopp-Systemen enorm an Bedeutung gewinnt,
• – durch das Vorgenannte CO2-Emission in einer Größenordnung von 15% und mehr vermieden wird,
• – der von der Kraftstoffpumpe im LPG-Tank im Betrieb vorzuhaltende Druck über dem LPG-Verdampfungsdruck gering sein kann,
• – die Kraftstoffpumpe im LPG-Tank keiner, die Pumpenlebensdauer vermindernde, Kavitation durch verdampfendes LPG ausgesetzt ist,
• – dass ein, dem Betrieb mit dem Kraftstoff Benzin vergleichbar, sicherer Betrieb des Otto-Motors ausschließlich mit dem Kraftstoff LPG möglich wird (auch bei einem Betriebszustand mit hohen Außentemperaturen und geringem Kraftstoffinhalt im Tank, der sogar beim Betrieb mit Benzin ein kritischer Zustand darstellt).

In addition, it is achieved by the invention that

• - the direct injection of LPG is possible, which would otherwise fail due to space and also for cost reasons,
• - the provision of a second fuel supply system for the supply of a normal pressure gasoline fuel, including the closed fuel system, which prevents the escape of fuel vapors from the fuel tank, is superfluous for technical reasons,
• - An operation of an Otto engine is possible only with LPG,
• - No expensive normal-pressure gasoline, preferably gasoline, more is needed to start the engine, which is particularly important in the use of start-stop systems enormously important,
• - avoided by the abovementioned CO2 emission of the order of 15% or more,
• The pressure to be maintained by the fuel pump in the LPG tank above the LPG evaporation pressure may be low,
• The fuel pump in the LPG tank is not exposed to pump life reducing cavitation by evaporating LPG,
• - that, comparable to the operation with the fuel gasoline, safe operation of the gasoline engine exclusively with the LPG fuel is possible (even in an operating state with high outside temperatures and low fuel content in the tank, which is a critical condition even when operating with gasoline) ,

It In the following, embodiments of the invention will be simplified illustrated and explained.

1 shows the monovalent version of LPG direct injection in gasoline engines, which is operated with the method for operating an internal combustion engine according to claim 1.

2 shows a bivalent version of LPG direct injection in gasoline engines, in which in the operating mode LPG also the method for operating an internal combustion engine according to claim 1 is used.

The 3a , b show a pressure regulator with internal evaporation pressure compensation, bypass and three variants of a device in the pressure regulator, which allow a short-term pressure increase.

In 1 press one, in a catch tank 3 housed fuel pump 2 , from the pressure-resistant LPG tank provided with the prescribed safety fittings 1 , LPG in liquid phase 4 into the fuel supply line 5 to the high-pressure fuel pump 6 out. In a preferred embodiment, the LPG flows through in liquid phase 4 on the way to the high-pressure fuel pump 6 a heat exchanger connected to an on-board air conditioning system 13 where it is additionally cooled. A hole 7 at a special location of the high pressure pump 6 attached, it allows the LPG in liquid phase 4 from the fuel supply line 5 at the entrance of the high pressure pump chamber in the high pressure pump over into the fuel return line 8th to the LPG tank 1 to flow. A valve controlled by the engine control in the high-pressure pump 6 allows the fuel required for combustion from the passing fuel flow into the high pressure pump chamber of the high pressure pump 6 drain where the fuel is 4 pressurized by the pump piston and via the high pressure fuel line 9 to the fuel rail 10 is pressed. The fuel rail 10 supplies the fuel injection valves 20 with the necessary fuel, which they inject with high pressure (40-200 bar) into the combustion chamber of the (not shown here) engine. On the way from the high pressure pump 6 back to the LPG tank 1 by the fuel flows 4 one with a bypass 12 provided pressure regulator 11 and a heat exchanger connected to the air conditioner 13 where the fuel 4 is cooled again so that he, despite the in the high-pressure fuel pump 6 heat input, in the liquid phase back into the catch tank of the tank module 3 in the LPG tank. This avoids cavitation by evaporating LPG in the catch tank 3 and the associated load on the fuel pump 2 ,

For safety reasons, the control unit detects 16 over the pressure sensor 14 in all phases of operation, including the pre-emergence phase and the post-emergence phase with the engine stopped, the pressure in the low-pressure fuel circuit. Is from the control unit 16 no pressure detected in the system, then stops the control unit 16 the operation of the LPG fuel pump 2 and closes the solenoid valve 18 in the fuel flow. A leak of LPG 4 from the LPG tank 1 It is thus both in leaking as well as torn off fuel line 5 / 8th prevented.

The control unit 16 detects at standstill of the motor, induced by an electrical load, voltage drop of the battery and uses it as a control pulse to the fuel pump 2 to get started. This ensures that a cooling fuel circulation in low-pressure fuel circuit is already set in motion when z. B. the lock of a motor vehicle is unlocked, so even before opening a vehicle door. At the same time the control unit opens 16 the bypass 12 of the pressure regulator 11 , what the hydraulic resistance in the fuel line to the hydraulic resistance of the pressure regulator 11 reduced. This increases the fuel volume flow and thus the cooling effect.

After turning off the engine the control unit registers 16 over the temperature sensor 15 the temperature of the high pressure pump 6 , If this exceeds a fixed first value, the control unit continues 16 with the help of the fuel pump 2 in the LPG tank 1 a cooling fuel circulation in progress. To relieve the battery and to increase the cooling effect opens the control unit 16 the bypass 12 of the pressure regulator 11 so that its hydraulic resistance is bypassed. The cooling fuel circulation is maintained until a lower second defined temperature at the high pressure pump 6 is fallen short of. This control loop will run through until the controller 16 does not detect any temperature increase beyond the first defined temperature. In a control variant of the cooling fuel pump lag in the low-pressure fuel circuit, the temperature-dependent changing evaporation pressures in the LPG tank are taken into account. The control unit 16 registered after switching off the engine via the temperature sensor 15 the temperature of the high-pressure fuel pump 6 and compares them to the fuel temperature in the LPG tank 1 that has a temperature sensor 17 on or in the LPG tank 1 determined. If the temperature rises at the high-pressure fuel pump 6 a first defined, based on the vapor pressure curve of the LPG, difference to the temperature of the fuel 4 in the LPG tank 1 , puts the control unit 16 with the help of the fuel pump 2 in the LPG tank 1 a cooling fuel circulation in progress. To relieve the battery and to increase the cooling effect opens the control unit 16 the bypass 12 of the pressure regulator 11 so that its hydraulic resistance is bypassed. The cooling fuel circulation is maintained until a second defined temperature difference between the temperature at the high pressure pump 6 and the temperature of the fuel 4 in the LPG tank 1 is fallen short of. This control loop will run through until the controller 16 does not detect a temperature increase beyond the first defined temperature difference.

In 2 is the equivalent bivalent version of direct injection of liquid phase LPG 4 pictured in petrol engines. There is a fuel supply line in the low pressure area 24 for fuel at normal pressure and normal temperature (normal pressure fuel) 21 , preferably gasoline, from an in-tank fuel pump 12 in normal pressure fuel tank 20 is charged and a corresponding fuel supply line in the low pressure range 5 for LPG. The fuel supply lines 5 / 24 for the two fuels 4 / 21 be upstream of the high-pressure fuel pump 6 coupled and through a check valve 31 and two solenoid valves 25 / 32 locked against each other. This ensures that only one of the two fuels 4 / 21 to the high-pressure fuel pump 6 is encouraged. In addition, in the low pressure region of the fuel supply of the normal pressure fuel, a second fuel pump 23 needed to switch from LPG to liquid phase 4 on the normal pressure fuel 21 the evaporation of LPG in liquid phase 4 to prevent.

This procedure is also controlled by the control unit 16 , In detail, the switching process in the DE 101 46 051 described.

An important difference in the fuel supply of the two fuels 4 / 21 also lies in the fact that the normal pressure fuel 21 without return, while the fuel LPG in liquid phase 4 with a fuel return 8th from the high-pressure fuel pump 6 in the LPG tank 1 operated as a fuel circuit, without which he would not be reliable.

This difference of fuels 4 / 21 in operation is also controlled by the controller 16 organized by fuel-specific the return valve 30 downstream of the output of the low pressure region of the high-pressure fuel pump keeps open or closed, namely opened in the liquid phase fuel LPG 4 , whereby a fuel circuit is generated here and closed at the normal pressure fuel 21 , The EP 06 023 298.0 specifies the requirements that the connection of the return line 8th to the high-pressure fuel pump 6 must fulfill in order for it to fulfill its function.

In the in the 3a , B illustrated embodiments of the fuel pressure regulator according to the invention 11 for a fuel injection system for the injection of liquid phase LPG 4 in a gasoline engine, set in a regulator housing 112 movable pressure regulating piston 111 the pressure-regulating component. The conical tip 117 of the pressure regulating piston 111 sits in a corresponding conical receptacle of the controller housing 112 and thereby seals. The sealing force is provided by a spring 113 determined on the back of the pressure regulating piston 111 suppressed. The pressure regulating piston 111 is axial with a flow bore 115 Mistake. It causes the evaporation pressure of the LPG 4 in the liquefied gas tank 1 also on the back of the pressure regulating piston 111 takes effect. The resulting pressure balance between the front and back of the pressure regulating piston 111 As a result, the force of the spring 113 not even the evaporation pressure of the LPG 4 must hold (internal evaporation pressure compensation). Through this internal pressure equalization is in the LPG tank 1 prevailing evaporating pressure compensates, so that the overpressure caused by the fuel pump 2 in the LPG tank 1 in order to prevent the LPG from evaporating, from the evaporation pressure of the LPG 4 in the LPG tank 1 and thus independent of its current temperature. The one from the fuel pump 2 generated overpressure has now only the function of overcompensating the increase in the evaporation pressure, which the LPG in liquid phase 4 on his way from the LPG tank 1 to the fuel high pressure pump 11 by heat input from different sources, such as the fuel pump 2 itself, the electromagnetic shut-off valve 18 at the exit of the LPG tank 1 or the high-pressure fuel pump 6 experiences. This requires, as long as in the low-pressure fuel cycle 1 - 13 fuel 4 is circulated, with favorable design of the low-pressure fuel circuit 1 - 13 , only a slight increase in pressure compared to the fuel pressure in the LPG tank 1 ,

The situation is completely different with engine standstill after the engine has been operated. The lack of fuel circulation causes a large pressure difference between the evaporation pressure of the fuel 4 in the LPG tank 1 and, crucially for the operation of the engine, the evaporation pressure of the fuel 4 at the entrance to the high-pressure pump chamber in the high-pressure fuel pump 6 , Without the inventive method and the embodiment of the pressure regulator according to the invention, the spring force of the spring would have 113 Be sized to use the fuel pump 2 in the LPG tank 1 Forced to permanently generate an overpressure that is higher than this evaporating pressure difference at engine standstill with warm engine, thus the fuel 4 also at the entrance to the high-pressure pump chamber in the high-pressure fuel pump 6 remains in the liquid phase. As a result, the fuel pump would have to 2 in the LPG tank 1 Even in the vast majority, uncritical operating conditions permanently create an unnecessarily high pressure with all the associated disadvantages.

The solution according to the invention of this problem 3a is that the compression spring 113 against a second, displaceable piston 114 (Booster piston) is stored. In the case of warm start this pressure booster piston 114 now shifted so that it is the pressure-generating spring 113 compressed by a predetermined amount and thereby generates a higher spring tension, which in turn via the pressure regulating piston 111 a higher fuel pressure in the low-pressure fuel circuit 120 causes.

3a shows two variants of the pressure increase by displacement of the pressure increasing piston 114 , In one variant, the displacement of the pressure increasing piston 114 by the energization of an external solenoid 119 and in the other by the at the entrance of the pressure control valve 11 branched off and on the back of the pressure booster piston 114 guided fuel pressure of the fuel low pressure circuit 120 causes. The positive feedback of the control loop increases the fuel pressure 120 in the low-pressure fuel circuit very fast. A pressure limit prevents ver that the pressure increase a predetermined, the flow rate of the fuel pump 2 in the fuel tank 1 exceeds exceeding level. The duration of the pressure increase is determined by that of the control unit 16 controlled valve 19 determined by the pressurization of the pressure booster piston 114 with the fuel pressure of the low-pressure fuel circuit 120 completed. About the leakage at the pressure booster piston 114 then finds a gradual reduction of the pressure increase in the pressure regulator 11 instead, in parallel with the reduction in fuel temperature in the high-pressure fuel pump 6 runs.

The inventive solution of the problem in 3b This is the back of the pressure control piston 111 in addition to the pressure of feather 113 to apply a defined pressure which is higher than the evaporation pressure of the LPG 4 in the LPG tank 1 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10146051 [0007, 0007, 0008, 0032]
• - EP 1095214 B1 [0013]
• - DE 10360977 [0013]
• - DE 10360977 A1 [0014]
• - EP 1095214 B [0015]
• EP 06023298 [0016, 0034]

Claims (17)

Method for operating an internal combustion engine, which includes, among other things, a fuel tank ( 1 ), a low-pressure fuel circuit ( 1 - 13 ), an electrical system and a battery for the supply thereof, characterized in that prior to starting the internal combustion engine the following steps are carried out: a) detecting a signal induced by an electrical load signal by detecting a signal indicative of a drop in the battery b) start of fuel circulation in the low-pressure fuel circuit ( 1 - 13 ) in response to the detected signal, which is used as a start pulse for the start of fuel circulation Method according to claim 1, characterized in that that as a fuel LPG and as an internal combustion engine a gasoline engine is used. A method according to claim 1 or 2, characterized in that after switching off the internal combustion engine upon reaching or exceeding a predetermined first temperature or a first, in particular between the temperature of a high-pressure fuel pump ( 6 ) and the fuel temperature in the fuel tank ( 1 ) measured, temperature difference is a fuel circulation by the fuel low pressure circuit is started. Method according to claim 3, characterized that the fuel circulation takes place until a reaches the second predetermined temperature or temperature difference is below the first temperature. Method according to one of the preceding claims, characterized in that a in the low-pressure fuel circuit ( 1 - 13 ) on the return side provided pressure regulator ( 11 ) while the fuel circulation is bypassed when the internal combustion engine is switched off. Method according to one of the preceding claims, characterized in that at least one point in the fuel low-pressure circuit ( 1 - 13 ), preferably in a return line ( 8th ) thereof, a heat exchanger connected to a cooling device ( 13 ) of the circulated fuel ( 4 ) is flowed through. Method according to Claim 6, characterized that used as a cooling device on-board air conditioning becomes. Method according to one of claims 6 or 7, characterized in that a plurality preferably in one Component summarized heat exchanger is used. Method according to one of the preceding claims, characterized in that when starting the internal combustion engine, the pressure in the low-pressure fuel circuit ( 1 - 13 ) is raised according to a system-specific predetermined fuel evaporation pressure. Method according to one of the preceding claims, characterized in that the delivery rate of the from the fuel tank ( 1 ) of subsidized fuel ( 4 ) is regulated. Method according to one of the preceding claims, characterized in that falls below a predetermined Pressure in the low-pressure fuel circuit the fuel production is prevented. Internal combustion engine which, inter alia, a fuel tank ( 1 ), a low-pressure fuel circuit ( 1 - 13 ), an electrical system and a battery for supplying the same, and a control unit ( 16 ) for controlling the internal combustion engine, characterized in that the control unit ( 16 ) is configured to carry out, prior to starting the internal combustion engine, the steps of: utilizing a signal induced by an electrical load by detecting a signal representative of a drop in the voltage across the battery as a starting pulse for starting the fuel circulation; Fuel circulation in the low-pressure fuel circuit ( 1 - 13 ) as a lead before starting the internal combustion engine. Internal combustion engine according to claim 12, characterized in that in the fuel low-pressure circuit ( 1 - 13 ) a pressure regulator ( 11 ) is provided, which is designed, in the fuel circulation before the starting process, the fuel pressure in the fuel low-pressure circuit ( 1 - 13 ) and when starting the fuel pressure in the low-pressure fuel circuit ( 1 - 13 ). Internal combustion engine according to claim 13, characterized in that the fuel pressure regulator ( 11 ) a pressure regulating piston ( 111 ), which, in addition to the pressure of a compression spring ( 113 ), can be acted upon starting with a predetermined hydraulic pressure which is greater than the evaporation pressure of the fuel ( 4 ) in the fuel tank ( 1 ). Internal combustion engine according to claim 13, characterized in that the fuel pressure regulator ( 11 ) a pressure regulating piston with internal evaporation pressure compensation ( 111 ), which is acted upon by a pressure at start, by the pressure regulating piston with internal evaporation pressure compensation ( 111 ) a spring pressure from a compression spring ( 113 ) is exercised. Internal combustion engine according to claim 15, characterized in that the fuel pressure regulator ( 11 ) a control piston ( 114 ) whose displacement the pressure of the compression spring ( 113 ) on the pressure regulating piston ( 111 ) changed. Internal combustion engine according to claim 16, characterized in that the control piston ( 114 ) at the rear of the fuel pressure regulator ( 11 ) applied fuel low pressure ( 120 ) can be applied.