DE10038560B4 - Fuel supply system for an internal combustion engine, in particular of a motor vehicle - Google Patents

Abstract

Fuel supply system for an internal combustion engine, in particular of a motor vehicle,
- With at least one combustion chamber (12),
- With at least one first pump (2) by means of the fuel in a first pressure range (5) is conveyed,
- With at least one second pump (6) by means of which the fuel from the first pressure range (5) in a second pressure range (8) is conveyed,
- With at least one pressure accumulator (9) in the second pressure region (8),
- With injection valves (11) by means of which the fuel from the second pressure range (8, 9) directly into the combustion chamber (12) can be injected,
With at least one pressure regulating and / or controlling means (16) arranged in the second pressure area (8),
Wherein the second pump (6) is designed as an electric pump,
characterized,
- That the pressure regulating and / or controlling means (16) and the second pump (6) form a structural unit (21, 21 '), and / or
- that ...

Description

The The invention relates to a fuel supply system for an internal combustion engine in particular of a motor vehicle with a pressure accumulator and a Pump with which the pressure accumulator fuel can be supplied, and injectors, with which fuel can be injected directly into the internal combustion engine is.

At an internal combustion engine, for example, a motor vehicle ever higher Requirements for reducing fuel consumption and the exhaust gases produced in a simultaneously desired increased Power provided. For this purpose are modern

Internal combustion engines provided with a fuel supply system in which the supply of Fuel into the combustion chamber of the engine electronically, in particular with a computer-aided control unit, controlled and / or regulated.

at the so-called gasoline direct injection (BDE), it is necessary that the fuel is injected under pressure into the combustion chamber. For this purpose, an accumulator is provided, in which the fuel Pumped by a pump and placed under a high pressure becomes. From there, the fuel is then directly via injectors in the combustion chambers the internal combustion engine injected.

From the DE 195 48 278 A1 a method and a device for controlling an internal combustion engine with high-pressure injection, in particular for internal combustion engines with auto-ignition is known. In this case, fuel is conveyed by a prefeed pump into a low-pressure region and conveyed by a high-pressure pump into a high-pressure region, a so-called common rail. The prefeed pump conveys the fuel from a fuel tank, the tank, into a low pressure area and is designed as an electric fuel pump. Parallel to the electric fuel pump, a pressure relief valve is arranged, which directs fuel from the low pressure region back into the tank of the motor vehicle when exceeding a certain pressure. In the high pressure area, a pressure sensor is arranged, which detects the pressure in the common rail. Furthermore, a pressure regulating valve is arranged between the high-pressure region and the tank of the motor vehicle, which in response to a drive current from a certain adjustable pressure passes fuel from the high-pressure region back into the tank. It is envisaged that the electric fuel pump is controlled in accordance with a drive signal in the speed to adjust the flow rate to the current needs of the engine. In case of system errors, the pressure control valve can be used as an emergency valve for quickly lowering the pressure in the common rail.

The DE 198 53 823 A1 discloses a method for operating an internal combustion engine, in particular a motor vehicle, in which the fuel from a first, usually driven by an electric motor fuel pump and by a second, usually mechanical high-pressure pump is fed into a pressure accumulator of the internal combustion engine. The pumped amount of fuel is here by a corresponding influence of the electric motor driven first fuel pump changeable. In this way, the pressure accumulator each required amount of fuel is supplied. The delivery rate of the first fuel pump is controlled in dependence on the amount of fuel to be injected and / or the speed of the internal combustion engine and / or the temperature of the intake air and / or the battery voltage via a map. In order to balance tolerances of the various fuel pumps as well as age-related changes, the possibility is revealed of matching the characteristic map with each starting process of the internal combustion engine. For comparison, for example, the actual value of the pressure in the accumulator is measured and compared with a desired value of the pressure in the pressure accumulator as a function of the required amount of fuel. Depending on the comparison of the determined actual value and the desired value of the pressure in the accumulator, the characteristic map is adjusted. The pressure in the pressure accumulator is detected by a pressure sensor arranged in the high-pressure circuit. To control the pressure in the high-pressure accumulator, a pressure control valve is arranged in the high-pressure accumulator, which conveys excess fuel back into the tank of the motor vehicle. The pressure control valve can be opened and closed via an input signal. There is further provided an electronic control device to which the output signal of the pressure sensor is connected and which generates the input signals for the first fuel pump and for the pressure control valve. By this measure can be taken by the electronic control unit influence on the flow rate of the first fuel pump and the pressure in the high pressure region by the pressure control valve.

German Patent Application DE 199 03 272. 6-13 discloses a fuel supply system for an internal combustion engine, in particular of a motor vehicle, in which fuel is pumped by means of a pump into a pressure accumulator and injected directly into the internal combustion engine by injection valves. The possibilities are disclosed of driving the pump mechanically, that is to say by rigid coupling to the internal combustion engine, or of carrying out the pump as an electric pump. The whole system according to the not yet pre-published German Patent Application DE 199 03 272.6-13 has an electric fuel pump that conveys fuel from a tank into a low-pressure region. Starting from this low-pressure region, the fuel is conveyed by means of the high-pressure pump into a pressure region or a common rail. Starting from this pressure range, the fuel is injected by means of injection valves directly into the combustion chamber of the internal combustion engine. In the high pressure region of the system, a pressure sensor and a pressure control valve are also arranged. Both the electric high-pressure pump and the pressure sensor, the injection valves and the pressure control valve are connected to a control unit, which, inter alia, based on the data supplied by the pressure sensor performs at least the control of the electric high-pressure pump, the injection valves and the pressure control valve. To control the amount of fuel delivered, the possibility is disclosed to regulate the speed of the electric fuel pump according to the required delivery rate. The control of the pressure control valve is carried out with different for each constant duty cycle, which are selected according to the operating condition, such as start or normal operation. The peculiarity of the not yet published German patent application

DE 199 03 272.6-13 is to be seen in that the high-pressure pump is designed and is dimensioned that within a short period of time, specifically within a few revolutions of the internal combustion engine already the for the injection of fuel into the combustion chambers of the internal combustion engine sufficient pressure is present in the accumulator.

From the DE 197 42 993 A1 Further, a method for controlling a fuel pressure in a fuel rail is known in which the fuel pressure in the fuel rail is calculated and compared with a target pressure. In order to control the fuel pressure to the target pressure, it is provided to determine a desired current, with which an electric fuel pump is driven to achieve the desired fuel pressure.

Advantages of invention

One Fuel supply system for an internal combustion engine, in particular of a motor vehicle with at least a combustion chamber, with at least a first pump, by means of Fuel is conveyed in a first pressure range, with at least a second pump, by means of which the fuel from the first pressure range is conveyed in a second pressure range, with at least an accumulator in the second pressure range, with injection valves, by means of which the fuel from the second pressure range directly into the combustion chamber can be injected, with at least one a pressure-regulating and / or controlling means arranged in the second pressure area, wherein the second pump is designed as an electric pump, is opposite to that State of the art further developed in that the pressure regulating and / or controlling means and the second pump a structural unit form and / or that the pressure regulating and / or controlling agent integrated into the second pump. The advantages of the fuel supply system according to the invention lie u. a. in the compact size and the cheap costs for such a system.

A particularly advantageous embodiment of the fuel supply system according to the invention results from the fact that the second pump structurally separated from the surrounding the combustion chamber Engine block is arranged. This structural separation offers on the one hand Advantages of packaging in the engine compartment, which in the construction of a new motor vehicle of large Advantage is. On the other hand is due to the structurally separate arrangement a thermal decoupling from the combustion chamber enclosing the engine block guaranteed especially in hot start situations is advantageous because after parking the motor vehicle in the be called State at least the fuel that is still in the pump unit is not heated.

Favorable Way are a speed control device for controlling the second Pump and a control unit for the Control and / or regulation of the speed control device provided. By this speed control device according to the invention can the fuel supply system in particularly advantageous Way demand-driven and operated efficiently, as the speed adapted to the particular requirements of the internal combustion engine can be. This results in a further advantageous development in that the control unit an engine control unit the internal combustion engine is and that this engine control unit in addition to the control the pressure regulating and / or controlling agent is used. The advantage of this embodiment is that on an additional control device for the control and / or regulation of the speed control device can be dispensed with. This in turn has a positive effect on space requirements and costs out.

Advantageously, the pressure regulating and / or controlling means is designed as a pressure regulator and / or a pressure relief valve and / or a pressure control valve and / or a quantity control valve. In combination for this purpose, a pressure sensor is advantageously arranged in the second pressure range, which in the context of a preferred development in the structural unit of the pressure regulating and / or controlling means and the second pump is arranged. By virtue of these further developments according to the invention, in practice, a structural unit results from pressure generation, from pressure detection and from pressure influencing, whereby an almost complete, self-sufficient system for supplying fuel is made available.

A advantageous development provides that a pressure value representative Transfer signal from the pressure sensor to the control unit or to the engine control unit becomes. This can be the transmission the signal over a direct signal line or over an indirect signal line, in particular a vehicle bus system (like a CAN bus).

A sees preferred development of the fuel supply system in that at least one ignition device is assigned to the combustion chamber, by means of which the fuel in the combustion chamber is flammable. Also advantageous is a design of the internal combustion engine such that the fuel in the combustion chamber at least in one first mode during a Compression phase and in a second mode during a Injection is injectable. In particular, the use of direct Injection and the injection in the two different Operating modes in combination with the fuel supply system according to the invention results in a particularly fuel-efficient, space-saving and cost-effective design the internal combustion engine.

Further Features, applications and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, which are illustrated in the figures of the drawing. All described or illustrated features form for themselves or in any combination, the subject matter of the invention, regardless of their summary in the claims or their dependency as well as independently from their formulation or presentation in the description or in the drawing.

embodiments

1 shows a first embodiment of the fuel supply system according to the invention and

2 shows a second embodiment of the fuel supply system according to the invention.

In 1 a fuel supply system is shown, which is intended for use in an internal combustion engine of a motor vehicle. The fuel supply system is a so-called common-rail system which is used in particular in an internal combustion engine with gasoline direct injection (BDE system).

In 1 is with the reference numeral 1 a fuel tank or a tank characterized in the an electrically driven fuel pump 2 is integrated. Also shown is a central engine control unit (for example MOTRONIC) 3 that via a control line 4 the electric fuel pump 2 For example, the speed of the electric fuel pump 2 can regulate and / or control. The fuel is from the electric fuel pump 2 from the tank 1 via a first pressure line 5 to a second pump 6 directed. At the second pump 6 it is an electrically driven high-pressure pump, which consists for example of the combination of any electric motor and a mechanical pump. Via a control line 7 is the high pressure pump 6 with the engine control unit 3 connected, resulting from the engine control unit 3 Influence on the operating behavior of the high pressure pump 6 can be taken. The fuel is from the high pressure pump 6 placed under high pressure and passes through the high pressure line 8th in an accumulator 9 or a common rail. From this accumulator 9 starting from the fuel via high pressure feeders 10 to injectors 11 directed. By means of injectors 11 is the fuel directly into the combustion chambers 12 the internal combustion engine can be injected. In the illustration after 1 is schematically just a combustion chamber 12 shown. The injectors 11 are also via control lines 13 with the engine control unit 3 connected. About these control lines 13 can from the engine control unit 3 the individual injection time and the injection duration of the injection valves 11 be determined. In the area of the pressure accumulator 9 is still a pressure sensor 14 attached, the pressure in the accumulator 9 measures. The result of this measurement is via a signal line 15 the engine control unit 3 fed. Based on the pressure sensor 14 determined pressure data, the engine control unit 3 a pressure regulating and / or pressure control means 16 via a control line 17 drive. The pressure control and / or pressure control means 16 is according to the invention directly to the high-pressure pump 6 Flanged or in the pump 6 integrated. In any case, form the high pressure pump 6 and the pressure control and / or Drucksteurmittel 16 a structural unit 21 separated from the combustion chamber 12 enclosing engine block, indicated here by the structural unit 22 , can be arranged. From the pressure control and / or pressure control means 16 The excess fuel (the excess flow) passes through a pipe 24 back to the first printing area 5 in front of the high pressure pump 6 ,

With 18 is a speed control device for controlling the high-pressure pump 6 called, the for this purpose via the control line 20 with the high pressure pump 6 connected is. The signals, which speed of the speed control device 18 are to be controlled, the speed control device 18 via a control line 19 from the engine control unit 3 fed.

Furthermore, in 1 a variety of other lines 23 shown in or out of the engine control unit 3 lead in or out. These lines 23 symbolize the connections of the engine control unit 13 to the other components of the motor vehicle, according to the illustration 1 not shown.

As the pressure regulating and / or controlling agent 16 For example, a pressure regulator and / or a pressure relief valve and / or a pressure control valve and / or a quantity control valve can be used. If, in the case of a pressure regulator, a mechanical regulator (with integrated mechanical spring) is used, the pressure sensor can be used 14 be waived. In the event that a pressure relief valve, a pressure control valve or a quantity control valve is used, which is electrically controlled, this control is carried out in dependence on the pressure sensor 14 supplied data through the engine control unit 3 ,

It is also within the scope of the fuel supply system according to the invention, that the illustrated control unit 3 not the engine control unit of the internal combustion engine, but any other control device, for example, in the structural unit 21 can be integrated. It is also possible that the in 1 illustrated functions of the engine control unit 3 be fully variable to the engine control unit and another control unit to be divided. There is still the possibility that the speed control device 18 into the structural unit 21 is integrated with. In this way, the entire structural unit could 21 via pure control lines (ie without significant power transmission) from the engine control unit 3 be controlled. Another possibility is that the speed control device 18 (including the drive output stages) is integrated in the control unit or the engine control unit.

One of the big advantages of the structural separation of high-pressure pump 6 and engine block unit 22 consists in the thermal decoupling of the units. In the usual flanging a mechanical high-pressure pump to the engine block is heated by the thermal coupling of the fuel still in the pump when the vehicle is turned off with a hot engine. In such a situation, a subsequent hot start can lead to problems with vapor bubble formation and hence malfunction and / or misfiring. Another big advantage of the structural separation lies in the more flexible distribution of the components in the engine compartment. The existing volume under the bonnet can be used more flexibly in this way.

That of the pressure sensor 14 supplied signal that represents a pressure value in any form, as in 1 represented, via a signal line 15 to the engine control unit 3 transfer. In this case, it is still within the scope of the fuel supply system according to the invention, that for the transmission of the signal no direct signal line, but an indirect signal line, such as a vehicle-bus system (in particular a CAN bus) is used. All others in 1 The signal and control lines shown can also be realized both by direct signal lines and by an indirect connection via a bus system (eg CAN bus).

2 shows a second embodiment of the fuel supply system according to the invention. In the illustration after 2 are those elements that follow 1 correspond with the same reference numerals. The following is thus only on the differences of 2 to 1 received. The main difference of 2 to 1 lies in the fact that the pressure sensor 14 ' also in the structural unit 21 ' is integrated and for example on the high-pressure pump 6 attached or in the high pressure pump 6 is integrated. Also in this case, the signals representing a pressure are transmitted via a signal line 15 ' to the engine control unit 3 transfer. The resulting engine block unit 22 ' is according to 1 marked with a dashed line.

In the context of the fuel supply system according to the invention is of the engine control unit 3 influenced in various ways on fuel production. On the assumption that in the engine control unit due to the currently prevailing operating conditions and the requirements of the driver of the motor vehicle, a determination takes place as to how much fuel is required by the internal combustion engine, on the one hand a pilot control is possible in that the electric fuel pump 2 via a control line 4 is regulated in their speed. Another component of influencing is the pressure regulating and / or controlling agent 16 available via the control line 17 from the engine control unit 3 can be controlled. Finally, there is the speed control device 18 available through which the high pressure pump 6 can be controlled in the speed. All these measures combined result in a fuel supply system that works ideally on demand and at the same time a be especially low own energy needs. The possible achievable fuel savings through the use of an on-demand fueling system over a conventional (unregulated) fueling system are on the order of 1 to 2% of the total fuel consumption of the motor vehicle.

Especially in combination with the application in the gasoline direct injection results in particularly high consumption advantages. Characteristic of the gasoline direct injection is that the fuel in the combustion chamber at least in a first mode during a compression phase and in a second mode during an intake phase is injectable. The second mode, during which it is injected into the intake phase, corresponds approximately to the homogeneous operation of a motor vehicle, in which the power is controlled primarily via the air supplied to the combustion chamber. In this case, the power control takes place via the throttle valve. In the first mode, however, almost unthrottled is driven and the power is influenced primarily by the amount of fuel injected in the combustion chamber. In particular, in this mode, which is also referred to as shift operation, the fuel consumption of the internal combustion engine is lower and the speed of the high-pressure pump 6 can be lowered.

Another big advantage of the structural unit 21 respectively. 21 ' This is because it is easier for the various motor vehicle manufacturers to adapt their existing internal combustion engines to a direct fuel injection (BDE) system.

Claims (11)

Fuel supply system for an internal combustion engine, in particular of a motor vehicle, with at least one combustion chamber ( 12 ), - with at least one first pump ( 2 ) by means of the fuel in a first pressure range ( 5 ) is transportable, - with at least one second pump ( 6 ) by means of which the fuel from the first pressure range ( 5 ) into a second pressure range ( 8th ), - with at least one pressure accumulator ( 9 ) in the second pressure range ( 8th ), - with injection valves ( 11 ) by means of which the fuel from the second pressure range ( 8th . 9 ) directly into the combustion chamber ( 12 ) is injectable, - with at least one pressure regulating and / or controlling agent ( 16 ), which in the second pressure range ( 8th ), the second pump ( 6 ) is designed as an electric pump, characterized in that - the pressure regulating and / or controlling means ( 16 ) and the second pump ( 6 ) a structural unit ( 21 . 21 ' ), and / or - that the pressure regulating and / or controlling agent ( 16 ) into the second pump ( 6 ) integrated ( 21 . 21 ' ), and that a speed control device ( 18 ) for controlling the second pump in the structural unit ( 21 . 21 ' ) is integrated. Fuel supply system according to claim 1, characterized in that the second pump ( 6 ) structurally separate from the combustion chamber ( 12 ) enclosing engine block ( 22 ) is arranged. Fuel supply system according to claim 1, characterized in that the speed control device ( 18 ) for activation ( 20 ) of the second pump ( 6 ) is provided, and that a control unit ( 3 ) for the control ( 19 ) and / or regulation of the speed control device ( 18 ) is provided. Fuel supply system according to claim 1, characterized in that the control unit ( 3 ) an engine control unit ( 3 ) of the internal combustion engine and that a control ( 19 ) of the pressure regulating and / or controlling agent ( 18 ) by the engine control unit ( 3 ) he follows. Fuel supply system according to claim 1, characterized in that the pressure regulating and / or controlling means ( 16 ) is a pressure regulator and / or a pressure relief valve and / or a pressure control valve and / or a quantity control valve. Fuel supply system according to claim 1, characterized in that in the second pressure range ( 8th . 9 ) at least one pressure sensor ( 14 ) is arranged. Fuel supply system according to claim 6, characterized in that the pressure sensor ( 14 ' ) in the structural unit ( 21 ' ) from the pressure regulating and / or controlling agent ( 16 ) and the second pump ( 6 ) is arranged. Fuel supply system according to claims 3 and 6, characterized in that a pressure value representing signal from the pressure sensor ( 14 . 14 ' ) to the control unit ( 3 ) transferable ( 15 . 15 ' ). Fuel supply system according to claim 8, characterized in that for the transmission of the signal, a direct signal line ( 14 . 14 ' ) or an indirect signal line via a vehicle bus system, in particular a CAN bus, is provided. Fuel supply system according to claim 1, characterized in that the combustion chamber ( 12 ) at least one ignition device is assigned, by means of which the fuel in the combustion chamber ( 12 ) is flammable. Fuel supply system according to claim 1, characterized in that the fuel in the combustion chamber ( 12 ) is injectable during a compression phase at least in a first mode and during a suction phase in a second mode.