EP2476890B1 - Supply device with a fuel transport device and use of such a supply device - Google Patents

Description

The invention relates to a supply device with a fuel delivery device for a fuel collector, in particular for a common rail injection device of an internal combustion engine, with the features in the preamble of claim 1. The invention further relates to a use of a pertinent supply device.

For fuel supply of combustion chambers, in particular self-igniting internal combustion engines, such as diesel engines, pressure-controlled or stroke-controlled fuel injection devices can be used. As fuel injectors are pump-nozzle devices or pump-line devices, such as storage-injection systems (common rail) is used. Such common rail injection systems make it possible to adapt the injection pressure to the respective load and the speed of the relevant internal combustion engine. In order to achieve high specific performance of such internal combustion engines and to minimize the emissions of such internal combustion engines, the highest possible injection pressure is desired. The fuel for such fuel injectors is in a conventional manner with supply devices with a fuel delivery from a fuel tank by means of a fuel pump via a fuel line promoted the pertinent, designed as a common rail injector fuel pickup.

The DE 199 10 970 A1 describes a fuel injection device with a arranged between a pressure accumulator space and a nozzle chamber pressure booster unit whose pressure chamber is connected via a pressure line to the nozzle chamber, and with a connected to the pressure accumulator chamber bypass line.

The DE 102 47 210 A1 describes a fuel injection device for internal combustion engines having a fuel injector acted upon by a high-pressure fuel source and a pressure intensifier having a movable pressure interrupter, which is arranged between the fuel injector and the high-pressure source, which separates a connectable to the high-pressure source via a high-pressure line working space from a fuel injector acting high-pressure chamber, by Filling a back space of the pressure booster with fuel and by emptying the rear space of fuel, the fuel pressure in the high pressure chamber is variable.

The EP 1 387 079 A1 describes a common rail fuel injection system with a high-pressure pump, which supplies the rail system with fuel via a flow rate control, to which in turn fuel injectors for fuel injection of each cylinder of an internal combustion engine are connected. The high-pressure pump is supplied with fuel via a low-pressure feed pump, wherein the low-pressure feed pump draws fuel from a tank and forwards it via a fuel filter to the high-pressure pump. The operating pressure in the rail system is regulated by means of an electronic control unit.

The DE 197 41 297 A1 shows a fuel supply system of an internal combustion engine. Fuel is pumped from a tank to a distribution unit by a pump. Between the pump and the distributor unit, a spring-loaded pressure accumulator for the fuel is provided. The accumulator is controlled by a valve which is connected in parallel to the pump.

From the DE 10 2005 059 160 A1 shows a fuel system for an internal combustion engine, in which the fuel is conveyed from a tank to a distribution bar by two feed pumps connected in series. Between the feed pumps, a check valve and a spring-loaded pressure accumulator are provided.

The DE 101 49 412 C1 describes a generic supply device with a fuel delivery device for a fuel pickup, in particular for a common rail injector of an internal combustion engine, with at least one fuel tank, is conveyed from the fuel via a fuel line to the fuel consumer, wherein a biasing device formed by a hydraulic accumulator for the hydraulic bias of Fuel is provided in the fuel line in the direction of the fuel pickup, wherein the biasing means is provided adjacent to a biasing side with an energy storage such that fuel injected at a preselectable pressure is stored at this pressure level in the biasing means, wherein for performing a charge and / or discharge cycle between the pretensioner and the fuel line, a drive unit is provided, which is a connecting line between the biasing means and the fuel line such that at least the connecting line is partially blocked or released, wherein the energy storage is formed from a compressible medium in the form of a gas supply and wherein the fuel delivery device has at least a first conveyor unit and a second conveyor unit.

The known supply devices with a fuel delivery device are in particular in need of improvement in relation to the pressure build-up in their fuel line. As a result, a cold start behavior of an internal combustion engine, which is supplied by a common rail injector with fuel, improved.

A device for damping pressure pulsations in a fluid system is known from DE 103 27 408 A1 out.

Based on this prior art, the invention has for its object to provide a supply device with a fuel delivery device whose performance is improved.

The object is achieved with a supply device having the features of patent claim 1 in its entirety and with a use of a supply device for an internal combustion engine according to claim 11.

According to the characterizing part of claim 1, it is provided that the hydraulic accumulator is a membrane, piston or bellows accumulator, that blocking means prevent unwanted backflow of the fuel from the hydraulic accumulator in the direction of the first delivery unit and that the pretensioning device in the fuel line between the first and second delivery unit the connection line and the drive unit provided therein is switched on.

The fact that the biasing device is formed from a hydraulic accumulator in the form of a diaphragm, piston or bellows, can be achieved by the choice of hydraulic accumulator types basically different pressure levels in the fuel delivery line or make the total cost of the supply device.

Said first and second delivery unit may be formed as a low pressure pump or high pressure pump. In order to prevent unwanted fuel flow from the biasing means across the first conveyor unit, blocking means are provided according to the invention, in particular in the form of a check valve, which prevent unwanted backflow of the fuel in the direction of the first conveyor unit.

The biasing means is introduced via the connecting line with the drive unit between the first and second delivery unit in the fuel line. In this case, the first delivery unit can provide fuel at a lower pressure and the second delivery unit can provide fuel at high pressure to the fuel collector. In this way, the input side of the second delivery unit fuel is present at a defined pressure level fitting. Cavitation in the second conveyor unit is prevented by this structural measure.

By the biasing means ensures that in the fuel line constantly a fuel pressure is applied, which is adapted to supply a fuel pickup and preferably a high-pressure fuel source with fuel at a suitable pressure level. In particular, pressure fluctuations of the fuel pressure in the pertinent injector at the start of an internal combustion engine are thereby avoided. Overall, emissions of the internal combustion engine can thereby be reduced in addition to an improved starting behavior of the internal combustion engine. In addition, a means is provided by the drive unit for supplying fuel to or from the biasing device as a function of the different operating phases of the fuel pickup.

Advantageously, the first conveyor unit supplies fuel in a charging cycle to a biasing side of the biasing device, in a discharge cycle Releases fuel under bias in the assignable fuel line again. As a result of this structural measure, fuel can be conveyed to a biasing side of the pretensioning device during operation of the internal combustion engine as well as before or after operation of the internal combustion engine, and can also be withdrawn again. The biasing device thus causes via the hydraulic bias of the fuel in the fuel line also a feed possibility of fuel in the pertinent fuel line.

The drive unit can be designed as a valve, in particular as a 2/2-way switching valve. Also by this constructive measure, the manufacturing cost of the supply device can make advantageous.

In a fuel return line from the fuel collector in the direction of the fuel tank, a branch line may be provided, which opens onto the energy storage side of the biasing device.

A fuel filter device may be provided between the first conveyor unit and the blocking means in order to be able to supply prefiltered fuel to the second conveyor unit.

To improve the cold start characteristics of the internal combustion engine, the biasing device is advantageously switched into the discharge cycle at the beginning of the starting process and at the beginning of the operation of the first conveying unit. The biasing device thus assists both the pressurization of fuel in the fuel delivery line and the delivery of fuel in the fuel delivery line to the first delivery unit. In particular, the common rail system is directly supplied with fuel via the biasing device, even if the respective delivery unit due to the cold start process only one can apply low flow rate. In that regard, the biasing device serves as a kind of bridging until the normal high pressure supply is ensured.

Fig. 1

einen schematischen Schaltplan eines ersten Ausführungsbeispiels der Versorgungsvorrichtung für eine Kraftstofffördereinrichtung für einen Kraftstoffabnehmer in Form einer Common-Rail-Einspritzeinrichtung einer Dieselbrennkraftmaschine; und

Fig. 2 bis 5

weitere Ausführungsbeispiele eines jeweiligen schematischen Schaltplans einer Versorgungsvorrichtung mit einer Kraftstofffördereinrichtung.

In the following, the supply device according to the invention will be described with reference to various embodiments according to the drawings. It shows the

Fig. 1

a schematic circuit diagram of a first embodiment of the supply device for a fuel delivery device for a fuel pickup in the form of a common rail injector of a diesel engine; and

Fig. 2 to 5

Further embodiments of a respective schematic circuit diagram of a supply device with a fuel delivery device.

The embodiments of the Fig. 2 and 5 are merely illustrative of the background of the invention and are not the subject of a claim.

In the Fig. 1 is shown in a schematic circuit diagram as a whole designated 1 supply device with a fuel delivery device 3 for conveying fuel for a fuel pickup 5. The fuel collector 5 is in the in the Fig. 1 to 5 shown embodiments of the supply device 1 shown as a common rail injection device 7 for a diesel internal combustion engine not shown in detail. The supply device 1 has a fuel tank 9, is conveyed from the fuel via a fuel line 11 to the fuel pickup 5. Further, to the supply device 1 is a biasing means 13 belonging to the hydraulic bias of the fuel in the fuel line 11 in the direction of the fuel pickup fifth

In the fuel line 11, a first conveyor unit 15 is introduced, which supplies fuel in a charging cycle to a biasing side 17 of the biasing device 13. The biasing device 13 further comprises an energy storage 19, which serves to stockpiled fuel fed on the biasing side 17 with a predetermined elevated pressure level in the biasing device 13. As the Fig. 1 to 5 show, to the fuel conveyor 3 at least one further, second conveyor unit 21 belonging, wherein the biasing means 13 is connected between the first and the second conveyor unit in the fuel line 11. The first delivery unit 15 provides fuel of lower pressure and the second delivery unit 21 high pressure fuel to the fuel pickup 5 available. For carrying out a charging and / or discharging cycle between the pretensioning device 13 and the fuel line 11, a drive unit 23 is provided, which controls a connecting line 25 between the pretensioning device 13 and the fuel line 11 so that at least the connecting line 25 is partially blocked or released.

The biasing device 13 is formed in the embodiments shown from a hydraulic accumulator 27, which in the form of a membrane memory (see. Fig. 1 and Fig. 4 ) or in the form of a piston accumulator (cf. Fig. 2 and Fig. 3 ) or in the form of a bellows storage (cf. Fig. 5 ) is trained.

In the exemplary embodiments shown, the drive unit 23 is formed from a valve 33, in particular from a 2/2-way switching valve. The first conveyor unit 15 is designed as a low pressure pump and the second conveyor unit 21 is formed as a high pressure pump. Instead of the respective delivery unit, in particular in the form of the high-pressure pump could also be a pressure booster (not shown) occur. In order to prevent a backflow of fuel from the biasing device 13 in the direction of the first conveyor unit 15, blocking means 35 are introduced in the form of a check valve 37 in the fuel line 11. As the Fig. 2 and 5 show is in a particularly advantageous embodiment of the supply device, a branch line 41 is provided, which comes from a fuel return line 39 from the fuel pickup 5 coming to the side with the energy storage 19 of the biasing device 13. By this design measure, the energy storage 19 may be supported in its effect on the biasing side 17 of the hydraulic accumulator 27.

For filtering the fuel, which is conveyed in the direction of the second conveying unit 21 with the aid of the first conveying unit 15, a fuel filter device 43 is introduced into the fuel line 11 between the blocking means 35 and the first conveying unit 15.

In addition to the different types of hydraulic accumulator 27, the embodiments differ in the Fig. 1 to 5 In particular, by various types of drive unit 23. In all the embodiments shown, the drive unit 23 is formed as an electrically operated spring-centered 2/2-way switching valve, however, individual valve elements 45 of the valves 23 shown are formed differently from each other. The initial positions of the valve elements 45 of all valves 23 shown is a "closed position" in that the connecting line 25 is closed by the valve element 45, wherein in the embodiment in FIG Fig. 3 a check valve 47 and in the embodiment in Fig. 4 a lock block 49 is used with two oppositely acting check valves. By energizing the relevant valve 23, which takes place via a control device, not shown, depending on the charge or discharge cycle to be carried out with the biasing means 13, the valve element 45 in all embodiments of Fig. 1 to 5 moved to an "open position" to the effect that the connecting line 25 is opened by moving the valve member 45 in the direction of the figures to the right to a passage position. Fuel can in this case from the bias side 17 of the relevant Hydrospeichers 27 are introduced into the fuel line 11 under pressure of the prevailing pressure levels, wherein the further flow direction of the fuel in the fuel line 11 in the direction of the second conveyor unit 21 is predetermined by the respective blocking means 35. In the embodiments shown in all figures, this switching position of the valve element 45 also corresponds to the switching position in which the hydraulic accumulator 27 is refilled with fuel. Among other things, the operation of the first conveyor unit 15 serves this purpose.

In the in Fig. 1 In addition, a bypass line 51 bridging the valve 23 is introduced into the connection line 25. In the bypass line 51 in turn from the fuel line 11 in the direction of the hydraulic accumulator 27 overflowable check valve 53 is mounted. The check valve 53 can ensure the charging cycle of the hydraulic accumulator 27 independently of the respective switching position of the valve element 45.

The supply device 1 shown can so far to improve the cold start characteristics of an internal combustion engine, not shown, of which only the common rail injector 7 in the form of a high-pressure rail 55, are connected to the four fuel injectors 57 contribute, by at the latest at the beginning of the starting process the internal combustion engine and the operation of the first conveyor unit 15, the biasing means 13 is switched by the respective drive unit 23 in a discharge cycle. A further fuel filter device 59 is provided between the fuel tank 9 and the first conveyor unit 15 in order to clean off the tank contents before being supplied to the pertinent low-pressure pump 15.

Claims (8)

1. Supply device with a fuel delivery device (3) for a a fuel consumer (5), in particular for a common rail injection system (7) of an internal combustion engine, with at least one fuel tank (9), from which fuel is conveyed by means of a fuel line (11) to a fuel consumer (5), wherein a pressurising unit (13) formed by a hydraulic accumulator (27) is provided for hydraulic pressurising of the fuel (13) in the fuel line (11) in the direction of the fuel consumer (5), wherein the pressurising unit (13), apart from a pressurising side (17) is provided with an energy storage system (19) so that fuel supplied at preset pressure is stored at this pressure level in the pressurising unit (13), wherein a control unit (23) is provided for execution of a presssurising and/or depressurising cycle between the pressurising unit (13) and the fuel line (11), controlling a connection line (25) between the pressurising unit (13) and the fuel line (11), so that at least the connection line (25) is partly closed or released, wherein the energy storage (19) is formed from a compressible medium in the form of a gas reserve and wherein the fuel delivery device (3) comprises at least a first supply unit (15) and a second supply unit (21), characterised in that the hydraulic accumulator (27) comprises a diaphragm, piston or bellows accumulator, that blocking means (35) prevent an undesired return flow of fuel from the hydraulic accumulator (27) in the direction of the first supply unit (15) and that the pressurising unit (13) in the fuel line (11) is switched between first and second supply units (15, 21) via the connection line (25) and the control unit (23) provided therein.
2. Supply device in accordance with claim 1, characterised in that, in a first pressurising cycle, the first supply unit (15), supplies fuel to a pressurised side (17) of the pressurising unit (13) which, in an depressurising cycle, discharges fuel back into the fuel line (11) again under prelssure, after the first supply unit (15), seen in the fluid direction.
3. Supply device in accordance with claim 1 or 2, characterised in that the first supply unit (15) makes fuel available at low pressure and the second supply unit (21) makes fuel available at high pressure to the fuel consumer (5).
4. Supply device in accordance with one of the preceding claims, characterised in that die the control unit (23) is formed by a valve (33), in particular by 2/2-way switching valve.
5. Supply device in accordance with one of the preceding claims, characterised in that the first supply unit (15) is a low pressure pump and the second supply unit (21) is a high pressure pump.
6. Supply device in accordance with one of the preceding claims, characterised in that the blocking means (35) is provided in the form of a check valve (37).
7. Supply device in accordance with one of the preceding claims, characterised in that a fuel filter unit (43) is provided between the blocking means (35) and the first supply unit (15).
8. Application of a supply device in accordance with one of the preceding claims, characterised in that, for improvement of the cold start characteristics of the internal combustion engine, the pressurising unit (13) is switched to the depressurising cycle, at the latest at the beginning of the start procedure, along with operation of the first supply unit (15).

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