EP1576272B1 - Non-return fuel supply system - Google Patents

Abstract

The invention relates to a non-return fuel supply system (1) for an internal combustion engine, in particular in a motor vehicle, comprising at least one fuel pump (8), by means of which the fuel may be pumped from a first region (2) of a fuel tank into a pressurised region (12), connected to a fuel distributor (18), at least one suction jet pump (38) through which fuel supplied by the fuel pump (8) along a suction jet pump line (34) flows, by means of which fuel may be supplied from a second region (4) of the fuel tank into the first region (2), at least one means (20, 24, 30), for regulating and/or controlling the pressure in the pressurised region (12) and at least one non-return valve (14), by means of which at least a part of the pressurised region (12) may be sealed off from the fuel pump (8). According to the invention, the means (20, 24, 30) for regulation and/or control of the pressure in the pressurised region contains at least one electrically operated solenoid valve (40; 44), arranged downstream of the non-return valve (14) in the suction jet pump line (34).

Description

State of the art

The invention is based on a non-return fuel supply system according to the preamble of claim 1.

In a fuel supply system, fuel is pumped from a fuel tank from a fuel pump via a pressure line to a fuel rail on the engine with injectors or to a gasoline or diesel high pressure pump. Modern fuel supply systems have a tank installation unit inserted into the fuel tank, in which the fuel pump, a suction filter and a pot are integrated as a fuel reserve, which is filled by one or more suction jet pumps. Consequently, the suction jet pumps ensure that even when the fuel level in the fuel tank drops, the pot for providing the reserve fuel is always completely filled. The suction jet pumps are arranged in the branched off from the pressure line Saugstrahlpumpenleitung, which opens into the pot.

In some fuel supply systems, a return line branches from the fuel rail, leading back into the fuel tank. The fuel quantity not required by the internal combustion engine then flows through the fuel distributor via the return line back into the fuel tank. In contrast, in known from DE 199 51 132 A1 return-free fuel supply systems, however, no return line from the fuel rail to provided the fuel tank. Rather, the pressure in the fuel rail is adjusted as needed by the actual fuel pressure measured by a pressure sensor, compared within a control unit with a stored in a map target fuel pressure and depending on the control difference, the speed of the fuel pump is changed. A downstream of the fuel pump check valve in the pressure line ensures a seal of the pressure distribution containing the fuel rail. The control function takes place as long as the internal combustion engine is operated under load and a consumption amount of fuel is called up.

During phases in which the injection valves are closed and the fuel pump promotes no fuel in the pressure line, for example, engine stall, at high temperatures, the pressure in the one hand by the closed injectors and on the other hand, the closed return valve sealed pressure line rise, which is why mechanically actuated pressure relief valves or Diaphragm pressure regulator can be used see eg US 2002/0043253 to keep the pressure in the pressure line constant. A type of pressure relief valves must always be flushed during operation of a small overflow, which on the one hand requires continuous operation of the fuel pump and thus a certain energy consumption and on the other hand because of the small amount of flushing there is a risk that dirt deposits on the valve seat. Another type of pressure relief valve is closed during operation, so that after a phase of non-promotion and at the beginning of load operation because of the sudden onset of pressure increase over-greasing and higher pressure due to the higher leaks at the injectors higher HC emissions can occur. In addition, the opening pressure in both types of pressure relief valves can not be varied during operation.

Advantages of the invention

By the means controlling and / or controlling the pressure in the pressure region including at least one electrically actuated solenoid valve which is disposed downstream of the check valve in the Saugstrahlpumpenleitung, the solenoid valve can be included in the electronic control of the internal combustion engine, which is a control of the system pressure and the amount of fuel in allows all operating conditions of the internal combustion engine, in particular during the shift operation and at a standstill. Then, in contrast to the mechanically hydraulically actuated valves of the prior art via the electrically actuated solenoid valve depending on the opening duration variable opening pressures are adjustable. This is particularly advantageous for the compensation of temperature-induced pressure changes. Finally, with electrically actuated solenoid valves eliminates the need for constant flushing, which is why the fuel pump can be made smaller and significantly reduces the risk of contamination of the valve seat.

The measures listed in the dependent claims advantageous refinements and improvements of the patent claim 1 invention are possible.

Preferably, the solenoid valve is interposed between the check valve and the ejector and is driven by a central engine control unit, wherein the control of the solenoid valve in response to the pressure measured by a pressure sensor arranged in the pressure region.

By this measure, the solenoid valve is integrated into the electronic engine control, whereby variable opening pressures can be realized. The pressure range associated with injectors is preferably formed by a pressure line connecting the fuel pump to the injectors.

According to a first embodiment, an input of the solenoid valve is connected to the pressure range and an output to the ejector. In particular, the solenoid valve is de-energized closed during a standstill phase of the internal combustion engine and otherwise open, for example, during normal operation under load and energized during the coasting operation. In the case of, for example, a temperature-induced increase in pressure during the standstill phase, the solenoid valve is opened by signals from the engine control unit in order to keep the pressure in the pressure line constant. The electronic control of the solenoid valve, in particular, the holding pressure during coasting and engine downtime can be set arbitrarily. However, this also means that the function of the engine control unit must be temporarily maintained even during the stoppage phase of the internal combustion engine.

This can be omitted in a second embodiment, in which the solenoid valve is formed by a 2/3 way valve, of which an input to the pressure line, a first output to the suction jet pump and a second output is connected to a pressure relief valve. This 2/3 way valve is controlled by the engine control unit such that it connects the input to the second output in the de-energized state and the input to the first output when energized. Consequently, at standstill of the engine and de-energized deactivated engine control unit, the 2/3 way valve automatically, for example, by spring preload, in its de-energized position, in which the pressure line is connected to the pressure relief valve, via which then pressure is reduced. In normal load operation or coasting of the internal combustion engine, however, the 2/3 way valve is energized by the engine control unit, so that the suction jet pump is connected to the pressure line.

According to a further embodiment of the invention, the control of the solenoid valve takes place as a function of a degree of filling of the second region the fuel reservoir forming fuel tank with fuel. Within the fuel tank, the pot forming the first region of the fuel reservoir and receiving the fuel pump is then arranged as a reservoir for the reserve fuel. If the solenoid valve is closed when the fill level of the fuel tank is in a range between maximum charge and a level substantially flush with an upper rim of the pot, the fuel will no longer travel past the fuel injector via the closed solenoid valve promoted in the pot. Rather, the fuel then flows to compensate for levels from the fuel tank over the edge of the pot in this. With sufficient filling level of the fuel tank, the ejector can therefore be put out of operation, resulting in a significant reduction in the required by the fuel pump power, in an increase in system efficiency, in a lower electrical system load, in a lower tank heating and in a longer life of the fuel pump.

A further embodiment provides that the solenoid valve is formed by a switching valve, which is controlled clocked to control the driving pressure of the suction jet pump. According to an alternative to this, the solenoid valve may also be a proportional valve, which is controlled to control the driving pressure of the suction jet pump. In both cases, the suction jet pump can always be operated in a region of highest efficiency.

Consequently, the solenoid valve in the sense of a multiple function not only for a particularly advantageous control of the system pressure and the amount of fuel during coasting and at a standstill but also for further energy-saving measures.

Further advantageous embodiments and modifications of the invention are described in the remaining subclaims.

drawings

Fig.1

eine schematische Darstellung einer bevorzugten Ausführungsform eines erfindungsgemäßen Kraftstoffversorgungssystems;

Fig.2

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Kraftstoffversorgungssystems.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. In the drawing shows

Fig.1

a schematic representation of a preferred embodiment of a fuel supply system according to the invention;

Fig.2

a schematic representation of another embodiment of a fuel supply system according to the invention.

Description of the embodiments

The generally designated 1 in Fig.1 return-free fuel supply system is used for example for fueling an internal combustion engine of a vehicle and includes as essential components held within a swirl pot 2 of a fuel tank 4 tank installation unit 6 comprising a fuel pump 8 with a suction side filter 10, based on the fuel pump 8 disposed in a pressure-side pressure line 12 check valve 14 and a fuel injector 16 in fluid communication with fuel injectors 18 or a gasoline or diesel high-pressure pump. In a region between the check valve 14 and the fuel meter 18, a pressure sensor 20 measures the actual pressure in the pressure line 12 and sends via a signal line 22 a corresponding signal to a control unit, which is preferably formed by a central engine control unit 24 (MOTRONIC) and in which is controlled as a function of a control difference between the actual pressure and a demand-based desired pressure via an electrical line 26, a control signal to an electronic, connected to the fuel pump 8 via electrical lines 28 fuel pump controller 30 to the pressure in the pressure line 12 via the Regulate fuel pump 8 demand-dependent.

From a reference to the check valve 14 downstream portion of the pressure line 12 branches off at a branch point 32 from a Saugstrahlpumpenleitung 34, which branches, for example in several, preferably in two individual lines 36 branching in each branch 36 a fuel-carrying suction pump 38, wherein the individual lines 36 open into the swirl pot 2. The swirl pot 2 serves on the one hand as a fuel reservoir, on the other hand it prevents that with strong lateral acceleration the fuel pump 8 can no longer suck fuel for a short time, because this centrifugal force is concentrated in a remote from the suction side portion of the fuel tank 4. In the state through which fuel flows, the suction jet pumps 38 suck fuel from the area of the fuel tank 4 located outside the swirl pot into the two individual lines 36 and ensure a constant fuel level within the swirl pot 2 in a known manner.

Arranged in the suction jet pump line 34 branching off from the pressure line 12 is an electrically actuated solenoid valve 40, which is controlled by the central engine control unit 24 via a control line 42, preferably as a function of the measured pressure in the pressure line 12, the temperature of the fuel, the level and / or the engine operating conditions is controlled. The solenoid valve 40 is designed to open or close the cross section of the suction jet pump line 34. The solenoid valve 40 is preferably closed and energized closed open.

Against this background, the operation of the fuel supply system 1 is as follows: In load operation of the internal combustion engine, the fuel pump sucks 8 fuel from the swirl pot 2, wherein the fuel flow opens the check valve 14 under the effect of fuel pressure and a portion of the fuel flow at the branch point 32 in the Saugstrahlpumpenleitung 34th flows. In load operation, the engine control unit 24 energizes the solenoid valve 40, whereupon this is switched to the open position, so that the suction jet pumps 38 fuel the region of the fuel tank 4 located outside of the swirl pot 2 can suck into the swirl pot 2. The other part of the fuel flow is fed to the fuel meter 18 as required depending along the pressure line 12 in order to be injected via the injection valves 16 into combustion chambers of the internal combustion engine.

In the coasting mode, the injection valves 16 are closed, so that the fuel flow in the pressure line 12 is equal to zero, however, the Saugstrahlpumpenleitung 34 is flowed through the still energized and thereby kept open solenoid valve 40 and thus promoted fuel into the swirl pot 2.

During a standstill phase of the internal combustion engine, however, the engine control unit 24 switches the solenoid valve 40 de-energized, whereupon it closes. Consequently, the arranged downstream of the check valve 14 portion of the pressure line 12 and the upstream of the solenoid valve 40 disposed portion of the Saugstrahlpumpenleitung 34 is sealed by the closed injectors 16, the closed solenoid valve 40 and by the closed fuel pump 8 towards the check valve 14 against the environment, the Pressure of existing in these sections amount of fuel to be kept constant. Ternperaturbedingt however, the holding pressure may be too high, which is detected by the pressure sensor 20 and reported to the central engine control unit 24. Then, the solenoid valve 40 is briefly switched by the engine control unit 24 by a current pulse in the open position to reduce the predetermined holding pressure.

In the case of the second embodiment of the invention according to FIG. 2, the parts which are the same and function the same as in the preceding example are identified by the same reference numerals. As a solenoid valve here a 2/3 way valve 44 is used, of which an input 46 to the pressure line 12, a first output 48 to the suction jet 38 and a second output 50 is connected to a pressure relief valve 52. The 2/3 way valve 44 is controlled by the central engine control unit 24 such that it connects the input 46 to the second output 50 in the de-energized state and the input 46 to the first output 48 when energized. Preferably, the 2/3-way valve 44 is de-energized during a standstill phase of the internal combustion engine and otherwise energized, ie in load operation and in overrun operation. Consequently, at standstill of the engine and de-energized deactivated engine control unit 24, the 2/3-way valve 44 automatically, for example by spring preload, in its de-energized position, in which the pressure line 12 is connected to the pressure relief valve 52, via which then pressure can be reduced. In normal load operation or in coasting of the internal combustion engine, however, the 2/3 way valve 44 is energized by the engine control unit 24, so that the suction jet pumps 38 are connected to the pressure line 12.

According to a development of the first embodiment of Figure 1, the control of the solenoid valve 40 takes place in dependence on a degree of filling of the fuel tank 4 with fuel. If the solenoid valve 40 is closed, when the filling level of the fuel tank 4 is in a range between maximum filling and a level that is substantially flush with an upper edge 54 of the swirl pot 2, the fuel is no longer beyond that through the closed solenoid valve 40 except Operation set Saugstrahlpumpen 38 from the fuel tank 4 in the swirl pot 2 promoted. Rather, the fuel then flows to level compensation from the fuel tank 4 via the edge 54 of the swirl pot 2 in this. With sufficient degree of filling of the fuel tank 4, the suction jet pumps 38 can thus be put out of operation. Further, it is possible to vary the shutdown pressure as a function of the temperature and / or of the engine operating conditions.

The decommissioning of the Saugstrahlpumpen 38 and the variation of the Abstelldrucks can also by the 3/2-way valve 44 according to the second embodiment 2, if it is switched in the above-described, sufficient water level in the fuel tank 4 such that the input 46 is connected to the second output 50, which opens into the pressure relief valve 52. Then, the part of the suction jet pump line 34 located downstream of the 2/3-way valve 44 is shut off to a predetermined pressure level, so that the suction jet pumps 38 are no longer supplied with fuel.

Since the solenoid valves 40, 44 according to the embodiments of Figure 1 and Figure 2 are preferably switching valves, they can be controlled clocked to control the motive pressure of the ejector 38. According to an alternative to this, the solenoid valve 40, 44 may also be a proportional valve, which is controlled to control the driving pressure of the suction jet pump. By controlling the driving pressure, the suction jet pump 38 can then always be operated in a region of highest efficiency.

Claims (16)

1. Non-return fuel supply system (1) for an internal combustion engine, with

   - at least one fuel pump (8) by means of which fuel can be conveyed out of a first region (2) of a fuel reservoir into a pressure region (12) connected to a fuel distributor (18),

   - at least one suction-jet pump (38), through which flows fuel conveyed through a suction-jet pump line (34) by means of the fuel pump (8) and by means of which fuel can be conveyed out of a second region (4) of the fuel reservoir into the first region (2),

   - at least one means (20, 24, 30) regulating and/or controlling the pressure in the pressure region (12),

   - at least one non-return valve (14), by means of which at least part of the pressure region (12) can be shut off with respect to the fuel pump (8),

   characterized in that the means (20, 24, 30) regulating and/or controlling the pressure in the pressure region (12) contain at least one electrically actuable solenoid valve (40; 44) which is arranged downstream of the non-return valve (14) in a suction-jet pump line (34).
2. Non-return fuel supply system according to Claim 1, characterized in that the solenoid valve (40; 44) is arranged between the non-return valve (14) and the suction-jet pump (38).
3. Non-return fuel supply system according to Claim 1 or 2, characterized in that the solenoid valve (40; 44) is activated by an electronic engine control apparatus (24).
4. Non-return fuel supply system according to Claim 3, characterized in that the activation of the solenoid valve (40; 44) takes place as a function of the pressure measured by a pressure sensor (20) arranged in the pressure region (12).
5. Non-return fuel supply system according to one of the preceding claims, characterized in that an inlet of the solenoid valve (40) is connected to the pressure region (12) and an outlet is connected to the suction-jet pump (38).
6. Non-return fuel supply system according to Claim 5, characterized in that the solenoid valve (40) is closed, dead, during a standstill phase of the internal combustion engine and is open, live, otherwise.
7. Non-return fuel supply system according to one of Claims 1 to 4, characterized in that the solenoid valve is formed by a 2/3-way valve (44), of which an inlet (46) is connected to the pressure region (12), a first outlet (48) is connected to the suction-jet pump (38) and a second outlet (50) is connected to a pressure-limiting valve (52).
8. Non-return fuel supply system according to Claim 7, characterized in that the 2/3-way valve (44) is activated in such a way that, in the dead state, it connects the inlet (46) to the second outlet (50) and, in the live state, it connects the inlet (46) to the first outlet (48).
9. Non-return fuel supply system according to Claim 8, characterized in that the 2/3-way valve (44) is dead during a standstill phase of the internal combustion engine and is live otherwise.
10. Non-return fuel supply system according to one of the preceding claims, characterized in that the pressure region connected to the fuel distributor (18) is formed by a pressure line (12) which connects the fuel pump (8) to injection valves (16).
11. Non-return fuel supply system according to Claim 10, characterized in that the suction-jet pump line (34) branches off, downstream of the non-return valve (14), from the pressure line (12).
12. Non-return fuel supply system according to one of Claims 1 to 3, characterized in that the activation of the solenoid valve (40; 44) takes place as a function of a degree of filling of the second region (4) of the fuel reservoir with fuel.
13. Non-return fuel supply system according to Claim 12, characterized in that the first region of the fuel reservoir is formed by a pot (2) which receives the fuel pump (8) and which is arranged within the second region (4) of the fuel reservoir.
14. Non-return fuel supply system according to Claim 13, characterized in that the solenoid valve (40; 44) is closed when the filling level of the second region (4) of the fuel reservoir lies in a range between maximum filling and a level which is aligned essentially with an upper edge of the pot, and in that it is open otherwise.
15. Non-return fuel supply system according to one of the preceding claims, characterized in that the solenoid valve (40; 44) is formed by a switching valve which is activated, clocked, in order to regulate the propulsive pressure of the suction-jet pump (38).
16. Non-return fuel supply system according to one of Claims 1 to 3, characterized in that the solenoid valve is formed by a proportional valve (40; 44) which is activated in order to regulate propulsive pressure of the suction-jet pump (38).

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