DE102011005663A1 - Operating method of electric fuel pump in low pressure fuel system of internal combustion engine, involves changing opening timing of pressure limiting valve such that the actual performance reproaching value of fuel system is obtained - Google Patents

Abstract

An operating variable of engine demand characteristic field is pre-controlled, and feed-forward control for providing tolerance compensation value is performed, based on the output of electric fuel pump (3). The selected operating state of fuel system is monitored for a certain period of time, to increase the delivery rate of pump, by the time of opening of a pressure limiting valve (12). The opening timing of the valve is changed, such that the actual performance reproaching value of the low-pressure fuel system is obtained.

Description

The invention relates to an operating method for an electric fuel pump that promotes fuel from a tank of a fuel supply system in particular a motor vehicle to a consumer and in particular to the input side of a high-pressure pump, which conveyed this fuel under high pressure for injection into the combustion chambers of an internal combustion engine or provides the same, wherein the electric fuel pump is precontrolled in terms of their delivery capacity on the basis of at least one operating variable of the consumer or the internal combustion engine taking into account demand map and wherein in this pilot control provided for tolerance compensation Vorhaltewert is included by comparing with a measurable in the fuel system size to the actual present system behavior is adjusted. The state of the art is in addition to the DE 10 2007 062 215 A1 on the DE 10 2008 055 747 A1 directed.

In fuel supply systems of internal combustion engines, one or more electric fuel pumps (hereinafter also abbreviated to the letters "EKP") are used to convey the required fuel. In internal combustion engines, which work with direct injection of the fuel into the combustion chamber, an EKP serves as a prefeed pump in the following to the EKP so-called low-pressure fuel system for supplying one or more high-pressure fuel pumps (hereinafter also abbreviated with the letters "HDP") with the required fuel flow (Flow rate) and low fuel pressure (prefeed pressure) from the fuel tank. Although in the further description only one of an internal combustion engine and a high-pressure pump upstream of this is spoken, yet the present invention is applicable to any consumer of fuel and in particular to those in a motor vehicle.

For controlling one or more EKP of a fuel supply system of an internal combustion engine, various possibilities are known in the prior art. Thus, the control of the EKP in the form of a full control, namely a promotion of the maximum required fuel flow at a maximum required Vorförderdruck or in the form of a demand-driven control. In the case of on-demand control, in one embodiment, for example, only the delivery rate of the EKP is varied at a constant maximum supply pressure of the fuel system. This is a so-called load-speed control. In a further embodiment of the demand-dependent control, the delivery rate of the EKP and its pre-delivery pressure are regulated with the aid of a closed-loop pressure regulation using the measured values of a pressure sensor in the low-pressure fuel system. For this purpose, therefore, a sensor for detecting the fuel pressure in the low-pressure fuel system, d. H. in the area downstream of the electric fuel pump and upstream of the high-pressure fuel pump (HDP) required.

The known in the prior art types for controlling an EKP have, depending on the design to different degrees pronounced disadvantages. Thus, the application of the said full control of an EKP regardless of the actual momentary demand of the fuel supply system always promoted at maximum pre-feed pressure, the maximum amount of fuel required. This is associated with a high electrical power consumption of the EKP. A high electrical power consumption of the EKP leads to an increased load on the electrical components such as EKP, battery of a motor vehicle equipped with this fuel supply system, its electrical line system and generator or generally an electric power source. Therefore, these components may need to be made larger in size, resulting in increased weight and increased cost, or, for example, have a shorter life in the case of the battery. The increased consumption of electrical power also leads to a waste of generated electrical energy; in a motor vehicle with an internal combustion engine as the drive unit, this increases, for example, its fuel consumption.

A fuel supply system with constant or almost constant maximum prefeed pressure and only variable demand-dependent flow rate of the EKP can compensate for these disadvantages only partially, since the required prefeed pressure is not high in all operating conditions of a fuel supply system. This also leads to a high electrical power consumption of the EKP with the disadvantages described above. An above-mentioned fuel supply system with closed-loop pressure control. and a pressure sensor in the low-pressure fuel system can each demand the required. Optimally adjusting the pre-delivery pressure and also adjusting the delivery rate of the EKP according to demand, thus significantly reducing the electrical power consumption of the EKP. However, such a system is associated with high costs due to the required low-pressure fuel sensor.

In contrast, it is thus more advantageous, as is generally known (cf., for example, the two publications cited above), to determine the delivery rate of the EKP and the prefeed pressure of the low-pressure Fuel system by a suitable control of the EKP preconditioned as needed. The demand-dependent flow rate of the EKP and the required pre-feed pressure of the fuel system is preferably determined by means of demand maps as a function of the operating point (= "operating variable") of the engine and from a required setpoint control of the EKP determined and predetermined, due to which the EKP a certain Delivery service. A suitable desired control of the EKP can be realized, for example, in the form of a setpoint speed as a default for a suitable EKP control unit, for example, with subsequent speed control of the EKP. Another suitable setpoint control of the EKP can be, for example, a suitable voltage signal for triggering the EKP.

In the implementation of a low-pressure fuel system with a demand-dependent feedforward control of an electric fuel pump, the required flow of the EKP is piloted together with the required delivery pressure of the EKP, should due to the lack of information about the amount of actually adjusting fuel pressure in itself to the EKP subsequent and the EKP with containing so-called. Low pressure system for safe operation of the system so-called. Provision for different tolerances and scattering bands of components and components of the low-pressure fuel system are taken into account. A corresponding reserve value for the delivery volume flow and / or the delivery pressure of the EKP can therefore be provided to compensate for pressure losses in the flow through fuel filters (including the influence of their contamination) and / or pressure losses in the flow through fuel lines, and also to reduce the EKP delivery volume flow To compensate for hot promotion or wear, and also to compensate for tolerances or scattering bands of possibly supplied by the EKP suction jet pump (hereinafter also abbreviated to "SSP") and / or tolerances or scatter bands of the delivery characteristics of EKP. Furthermore, can be compensated by a number of such effects taking into account pressure drops in the flow of pressure relief valves or pressure relief valves and further safety margins of the fuel pressure to the vapor pressure curve of each fuel used pressure margins to account for dynamic effects (for example, local pressure minima due to high flow velocities) to avoid vapor bubble formation and to avoid cavitation, and more. These provisions are made in order to operate a fuel supply system with components at the boundaries of the scattering bands functionally reliable. By way of example, a copy of an EKP with a minimum delivery characteristic compared to a copy of an EKP with a medium delivery characteristic, with the same activation, promotes a lower volume flow. The control is carried out for a functionally reliable fuel supply system usefully in such a way that even an EKP can be installed with minimal funding characteristic. If, however, a copy of an EKP with a medium delivery characteristic is then installed, a correspondingly higher prefeed pressure is established in the low-pressure fuel system with the same activation. Such a higher feed pressure reduces the potential for lowering the electric power consumption of the EKP. This consequently also reduces the potential for reducing fuel consumption, for example of a motor vehicle with such a fuel supply system.

To point out a remedy for this problem is the object of the present invention.

A first solution to this problem is for an operating method according to the preamble of claim 1, characterized in that controlled and monitored by an electronic control unit in a selected operating condition of the fuel system over a certain period of time, the flow rate of the electric fuel pump continuously over the time of opening a in either the time profile of the electric current consumption of the electric fuel pump and / or the by means of a pressure sensor downstream of the high-pressure pump detectable and the fuel pressure in the fuel low pressure system corresponding fuel pressure is tracked is followed by the electric fuel pump subsequent low-pressure fuel system provided pressure limiting valve , wherein the opening time of said pressure relief valve is reflected in a change in the tracked history, so that it is known from which particular Aufn In the case of electric current, the known opening pressure of the pressure-limiting valve in the low-pressure fuel system is achieved and then the derivative value suitable for the actual system behavior is derived by comparison with a predefined desired pressure value at this specific power consumption.

A second solution to this problem is for a limited to the application in connection with a high pressure pump for an internal combustion engine operating method according to the preamble of claim 2, characterized in that controlled and monitored by an electronic control unit in a selected operating state of the fuel system, the electric fuel pump with a known delivery rate is operated while the detectable by means of a pressure sensor downstream of the high-pressure pump and the fuel pressure corresponding fuel pressure is detected in the fuel low pressure system and is compared with the known for this flow rate target pressure, whereupon from this comparison a suitable for the actual system behavior Vorhaltewert is derived.

Preferably, the respectively selected operating state is a state in which a start-up of the fuel supply system shut down for a relatively long period of time, on the order of at least several hours, is imminent. Another selected operating condition is a condition in which the high-pressure pump is not operated when the internal combustion engine is in operation, and this operating method is preferably performed by supplying an ejector pump provided in the fuel system in the selected operating condition by the electric fuel pump.

Generally speaking, the present invention provides for the behavior of certain components of a fuel supply system of an internal combustion engine or any consumer (as indicated in the preamble of claim 1) for reducing uncertainties with respect to the actual tolerance position of a fuel supply system or with respect to the actual position of a Fuel system within its scattered bands. By reducing these uncertainties, that is to say by the more precise knowledge of which components are installed with which tolerance position in a present fuel supply system, it is possible to reduce necessary provisions with regard to the precontrol of the delivery quantity and / or with regard to the prefeed pressure of the EKP.

A possible feature of this invention is the use of any frequent or continuous measurement of the electrical power consumption of the EKP in operation. With the help of the current signal is obtained for a specific selected control of the EKP feedback on the actual efficiency of the EKP. On the basis of this information, the tolerance position of the EKP or of the entire fuel supply system can be determined more precisely as follows: If an EKP with a specific activation value, which is determined from a desired delivery volume flow and a desired prefeed pressure, is actuated, then a steady state can occur Operating point of the EKP depending on the tolerance levels in the fuel system, for example, set an actual flow rate, which is equal to the desired flow rate and an actual pre-feed pressure, which is greater than the desired Vorförderdruck. Since the current consumption of an EKP with constant activation depends on the back pressure of the EKP and is present for a given EKP type in the form of maps with scatter bands, the tolerance position of the entire system can be determined in more detail up to the uncertainties from the unknown tolerance position of the EKP. If, for example, it is detected from the EKP current consumption that the pilot-operated, necessary system pressure is exceeded, the triggering of the EKP is consequently reduced. A corresponding adaptation of the EKP control can be done as often or continuously.

A particularly advantageous embodiment of this invention results from a measurement of the electric current consumption of an EKP by utilizing the basically known characteristic of one or more ejector pumps which is / are driven by the EKP, ie. H. whose propulsion flow is diverted from the flow of the EKP, and which is preferably arranged in the manner known in the art in the tank / are. The flow characteristic of a suction jet pump is generally known in relatively narrow limits. If the internal combustion engine is not operated, then the amount of fuel removed is practically equal to zero. Increasing from a low pressure level in the EKP containing and subsequent to this low pressure system starting the control or capacity of the EKP, it can be detected in such a system with therein pressure relief valve opening this pressure relief valve based on the current measurement of EKP.

For this purpose, first to the attached 1 referenced, in which in the form of a schematic diagram, a so-called. Low-pressure fuel system with an inventively operated electric fuel pump (EKP) is shown abstracted to the essential. It is with the reference number 1 a fuel tank of a motor vehicle and identified by the reference numeral 2 a so-called swirl pot, from which an electric fuel pump 3 (EKP) Fuel to a consumer, here a high-pressure fuel pump 4 (HDP) promotes, which provides an unillustrated internal combustion engine this subsidized fuel under high pressure for injection into the engine combustion chambers. In the burbot 2 Fuel is pumped out of the tank 1 by means of an according to the present sketch, although outside, but preferably within the tank 1 arranged suction jet pump 5 (SSP), whose flow (= motive flow) from the EKP 3 is provided and in a known manner after flowing through the SSP 5 together with the fuel flow delivered by this into the swirl pot 2 arrives. Accordingly, the subsidy line branches 6 the EKP 3 upstream of a pressure relief valve 7 in a side branch 8th who joined the SSP 5 ' leads. The already mentioned pressure maintenance valve 7 is in to the HDP 4 leading main branch 10 in which continue a fuel filter 11 is provided downstream of a pressure relief valve 12 containing return line 13 in the tank 1 , more precisely in the bob 2 , leading back, passing through this pressure relief valve 12 the maximum fuel pressure is set in the illustrated low-pressure fuel system.

Now, as described in the previous paragraph preceding paragraph, the output of the EKP 3 is continuously increased when the internal combustion engine is not operated, so initially the funded fuel flow only via the SSP 5 back to the tank 1 , more precisely in the bob 2 led, whereby the electrical current consumption of the EKP 3 viewed over time increases with a certain slope. Reference is made to the attached 2 in which the electric current consumption I of the EKP is plotted on the ordinate in the form of a curve I composed here of two straight lines A, B over the time axis t as abscissa. The first with still closed pressure relief valve 12 detected current consumption thus corresponds to the straight line section A shown in a solid line of the exemplary applied curve I.

After with a further increase in the output of the EKP 3 the pressure in the low-pressure fuel system continues to rise, opens the pressure relief valve at a certain time t _Ö 12 According to which the increase in the fuel pressure in the system significantly reduced or the fuel pressure does not increase at all. With further increase in the delivery rate of the EKP 3 increases over the pressure relief valve 12 in the tank 1 flowing fuel flow, while the fuel flow through the so-called. Trebleitung the SSP 5 remains constant or nearly constant due to the constant or nearly constant system pressure. A system design can now use the delivery characteristics of the EKP 3 and / or the pressure storage capability of the low-pressure fuel system and / or the flow characteristics of the pressure relief valve 12 in such a way that with a constant increase of the delivery rate the EKP with constant slope (ie with a linear increase of their in the 2 represented by the line C control. the EKP 3 ) the pressure increase in the low-pressure fuel system in time before opening the pressure relief valve 12 , ie before the time t _Ö another shape and / or slope in the course of power consumption 1 the EKP 3 causes, namely the straight section A, as an increase of the delivered fuel volume flow after opening the pressure relief valve 12 , in this case the straight section B.

For example, the following relationship applies to conventional electric fuel pumps: (partial derivation of the power consumption of the EKP after triggering the EKP at a constant delivery volume flow) is unequal (partial derivation of the power consumption of the EKP after triggering the EKP at constant back pressure).

The opening of the pressure relief valve can thus as in 2 visible for example by a kink in the measured current consumption I of the EKP 3 be detected. Since at the time t _Ö of opening the pressure relief valve both the fuel pressure in the low pressure system is known, which is equal to the opening pressure of the pressure relief valve 12 is, as well as the current control of the EKP 3 is known about the relatively narrow tolerated characteristics of the SSP 5 - The flow through the SSP 5 is at the known adjacent opening pressure of the pressure relief valve 12 sufficiently accurately known - to close the tolerance position of the EKP or the tolerance position of the entire fuel low pressure system. The accuracy of this tolerance narrowing is essentially determined by the accuracy of the characteristic of the SSP 5 and the accuracy of the detection of the opening of the pressure relief valve 12 certainly. However, these two quantities are generally much more accurate than a typical tolerance of an EKP, or a typical tolerance of the entire fuel supply system with respect to the relationship between EKP control, EKP delivery and fuel system pressure. As a result of the more precise knowledge of the present tolerance positions, the provisions for ensuring correct operation can be reduced, that is to say the triggering of the EKP 3 is reduced by the correspondingly unnecessary portions of a Fördervolumenstrom- or Druckvorhalts and it is derived for the as described actually determined system behavior suitable Vorhaltewert, for example, can be stored in tables in the said electronic control unit.

Alternatively or in addition to the method of operation described so far, a pressure sensor usually provided downstream of a high-pressure pump (HDP) can be used to achieve the object according to the invention, using a known type of such HDP, in which the high-pressure side of the HDP with the low-pressure side in certain operating states the HDP is in direct connection. In such operating conditions, the fuel pressure in the low-pressure system can thus also be measured by means of an existing high-pressure sensor, without the need for an independent pressure sensor in the low-pressure system. If, in such an operating condition, the EKP is a specific flow rate is controlled, it can be measured via the high pressure sensor in the low pressure system adjusting fuel pressure and from a comparison of the measured fuel pressure with a target fuel pressure of this feedforward can then consider the initially taken into account for the pressure or the flow rate of the EKP to a more suitable Preservation value to be adjusted. For example, starting from a state in which the measured fuel pressure is greater than the target fuel pressure stored in the electronic control unit for this control of the EKP, the control of the EKP can be reduced until equality exists between these two values.

When using such a high-pressure sensor, however, it may be that its accuracy in the low-pressure region is not sufficiently high, so that the low-pressure values measured with the high-pressure sensor can not be used directly. Nevertheless, a pressure sensor provided downstream of said high-pressure pump (HDP) can be used to achieve the present object if a known type of such HDP, in which the high-pressure side of the HDP is in direct communication with the low-pressure side of the HDP in certain operating conditions. For this purpose, a similar operating method is proposed, as described above with the aid of the measurement of the current consumption of the EKP in view of increasing delivery capacity increasing control of the EKP. The enclosed 3 in similar to 2 This measurement principle is illustrated by the time t of the fuel pressure D measured by a high-pressure sensor in the low-pressure system on the ordinate. Accordingly (again on the in connection with 1 explained system) during a steady increase of the control C ( 2 ) of the EKP 3 an opening of the pressure relief valve 12 be detected. Thus, starting from a low fuel pressure in the low-pressure system using an HDP with direct connection between its low-pressure side and high-pressure side in a certain operating state in just this operating state increases the control of the EKP 3 so that their flow rate increases, so first increases the fuel pressure, for example, according to the straight line piece A * of the curve D in 3 , Even if the high-pressure sensor measuring this pressure is too inaccurate to determine the exact value of the pressure, this pressure increase can nevertheless be clearly registered. The fuel pressure on the low pressure side and on the high pressure side of the HDP 4 decreases with increasing triggering of the EKP 3 as long as until the pressure relief valve 12 at time t _Ö opens. Is this pressure relief valve 12 open, the system pressure (low pressure equals high pressure) no longer increases. Opening the pressure relief valve 12 can thus be detected as a kink in the pressure curve D measured by the high pressure sensor; after opening the pressure relief valve 12 the pressure value D remains substantially constant and thus follows the dash-dotted straight line B * in 3 ,

Such a specified operating state of the high-pressure pump HDP, in which by means of a provided on the high pressure side of the HDP pressure sensor and the fuel pressure on the low pressure side of the HDP can be measured, for example, if there is an electrical voltage applied to the electrical elements of the fuel system, however the high-pressure pump downstream engine is not operated, so that the HDP is not put into operation. Such an operating state of the high pressure pump HDP, in which by means of a provided on the high pressure side of the HDP pressure sensor and the fuel pressure on the low pressure side of the HDP can be measured, but is also present, for example, when applied to the electrical elements of the fuel system, an electrical voltage and the Internal combustion engine is operated without the high-pressure pump is operated. In internal combustion engine operating points close to idling or in idle mode of the internal combustion engine is that of the electric fuel pump 3 already asked fuel pressure sufficiently high to be injected through the injectors into the combustion chambers of the internal combustion engine. In this case, therefore, the HDP is simply flowed through without pressure increase from the funded by the EKP fuel.

Such named operating states of the high-pressure pump HDP, in which by means of a provided on the high pressure side of the HDP pressure sensor and the fuel pressure can be measured on the low pressure side of the HDP, can thus serve as said "selected" operating state, in which the described operating method according to the invention is preferably carried out. As for the above-mentioned HDP operating state when the internal combustion engine is not operated, this selected operating state is a state in which start-up of the fuel supply system shut down for a long period on the order of at least several hours is imminent. Thus, for example, in connection with unlocking a motor vehicle in which such a fuel system is installed, the method according to the invention is carried out and the EKP are correspondingly activated. It is advantageous if previously the internal combustion engine of the motor vehicle for a longer period of time (in the order of magnitude of at least several hours) was out of operation, since then the Fuel pressure on the high pressure side of the HDP has degraded so far that it is smaller than the opening pressure of said pressure relief valve. In the case of operation of the internal combustion engine when not operated HDP this condition is fulfilled anyway.

Since both the fuel pressure in the low pressure system is known at the time of said opening of the pressure relief valve, because this is equal to the opening pressure of the pressure relief valve, as well as the control of EKP is known, can be on the relatively narrow tolerated characteristic of the SSP (the flow rate through the SSP is relatively accurately known at the applied opening pressure of the pressure limiting valve) close to the tolerance position of the EKP or the tolerance position of the entire fuel supply system. The accuracy of this tolerance narrowing is essentially determined by the accuracy of the SSP characteristic and the accuracy of the detection of the opening of the pressure relief valve. However, these are generally much more accurate than a typical EKP tolerance or typical tolerance of the entire fuel supply system in terms of the relationship between ECP drive, EKP delivery, and fuel system pressure. As a result of the more precise knowledge of the present tolerance positions, the provisions can be made to ensure a faultless. Reduce operating, that is, the control of the EKP is reduced by the correspondingly unnecessary portions of a Fördervolumenstrom- or Druckvorhalts, and it is derived for the described as actually described system behavior suitable Vorhaltewert, for example, be stored in tables in said electronic control unit can.

The method according to the invention results in an increase in the potential of a reduction in the hydraulic power of a pressure-variable low-pressure system with demand-dependent precontrol of the EKP and thus the potential for a further reduction of the electrical power consumption of the EKP by the targeted reduction of existing pressure reserves for a functionally reliable operation. This further reduces the mean system pressure in the low-pressure system. Due to the further reduced hydraulic system power and the further reduced electrical power consumption of the EKP, potentials for a further reduced fuel consumption of motor vehicles, for example, are tapped. The on average lower system pressure at variable pressure reserves and the lower electrical power consumption also makes it possible to develop potentials with regard to the design and dimensioning of components and components, wherein a lower average load of the components leads to further possible potentials in terms of installation space, weight and costs.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007062215 A1 [0001]
• DE 102008055747 A1 [0001]

Claims (5)

Operating method for an electric fuel pump ( 3 ), the fuel from a tank ( 1 ) of a fuel supply system, in particular of a motor vehicle, to a consumer and, in particular, to the input side of a high-pressure pump ( 4 , HDP) which delivers this pumped fuel under high pressure for injection into the combustion chambers of an internal combustion engine or the like, wherein the electric fuel pump ( 3 ) is precontrolled in terms of their capacity based on a at least one operating variable of the consumer or the internal combustion engine taking into account requirement map and wherein in this pilot control provided for tolerance compensation Vorhaltewert is adjusted by matching with a measurable in the fuel system size to the actual system behavior, characterized in that the output of the electric fuel pump is controlled and monitored by an electronic control unit in a selected operating state of the fuel system over a certain period of time ( 3 ) continuously over the time of opening (t _Ö ) one in itself to the electric fuel pump ( 3 ) subsequent fuel low pressure system provided pressure relief valve ( 12 ) is increased and thereby either the time course of the electrical power consumption of the electric fuel pump ( 3 ) and / or by means of a pressure sensor downstream of the high pressure pump ( 4 ) and the fuel pressure in the low-pressure fuel system corresponding fuel pressure is followed, wherein the opening time (t _Ö ) of said pressure relief valve ( 12 ) is reflected in a change in the tracked history, so that it is known from which particular intake of electric current, the known opening pressure of the pressure relief valve ( 12 ) is achieved in the fuel low pressure system and is then derived by comparison with a predetermined desired pressure value at this particular power consumption of the appropriate for the actual system behavior Vorhaltewert. Operating method for an electric fuel pump ( 3 ), the fuel from a tank ( 1 ) of a fuel supply system of a motor vehicle to the input side of a high pressure pump ( 4 , HDP), which delivers this pumped fuel under high pressure for injection into the combustion chambers of an internal combustion engine, wherein the electric fuel pump ( 3 ) is precontrolled in terms of their capacity on the basis of at least one operating variable of the internal combustion engine requirement map and wherein in this feedforward a provided for tolerance compensation Vorhaltewert is included, which is adjusted by comparison with a measurable in the fuel system size of the actual system behavior, characterized in that controlled and monitored by an electronic control unit in a selected operating state of the fuel system, the electric fuel pump ( 3 ) is operated with a known delivery rate and thereby the means of a pressure sensor downstream of the high-pressure pump ( 4 ) detectable and the fuel pressure in Kraftstoffnie derdrucksystem corresponding fuel pressure is determined and compared with the known for this flow rate target pressure, whereupon from this comparison a suitable for the actual system behavior Vorhaltewert is derived. Operating method according to claim 1 or 2, characterized in that the selected operating state is a state in which a commissioning of the shut down for a long period of time on the order of at least several hours fuel supply system is imminent. Operating method according to one of the preceding claims, characterized in that the selected operating state is a state in which the high-pressure pump ( 4 ) is not operated when the internal combustion engine is in operation. Operating method according to one of the preceding claims with a suction jet pump ( 5 ) as part of the fuel system, in the selected operating condition of the electric fuel pump ( 3 ) is supplied.

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