ITMI20011659A1 - FUEL SUPPLY SYSTEM FOR AN INTERNAL COMBUSTION ENGINE ESPECIALLY OF A MOTOR VEHICLE - Google Patents

Description

Description

State of the art

The invention relates to a method for operating a fuel supply system for an internal combustion engine, especially of a motor vehicle, in which fuel is pumped by a pump into a pressurized accumulator and by injection valves is directly injected. in the internal combustion engine. The invention also relates to a fuel supply system for an internal combustion engine, especially of a motor vehicle, comprising a pressurized accumulator and a pump, with which fuel can be supplied to the pressurized accumulator, and comprising injection valves , with which fuel can be injected directly into the internal combustion engine. The invention also relates to a control apparatus for an internal combustion engine, especially of a motor vehicle, as well as a storage medium for a control apparatus of an internal combustion engine, especially of a motor vehicle.

Increasingly high requirements are imposed on an internal combustion engine, for example of a motor vehicle, with regard to a reduction in the consumption of fuel and the exhaust gases produced, with an increased power, at the same time required. Modern internal combustion engines are equipped with a fuel supply system for this purpose, in which the fuel supply to the combustion chamber of the internal combustion engine is electronically controlled and / or regulated, especially with a control unit. computer supported.

In the case of the so-called petrol direct injection (BDE), the fuel must be injected under pressure into the combustion chamber. For this purpose, a pressurized accumulator is provided, in which the fuel is pumped by means of a pump and is brought to a high pressure. From here, the fuel is then injected directly, via injection valves, into the combustion chambers of the internal combustion engine.

Document DE 19548 278 A1 discloses a method and a device suitable for managing an internal combustion engine with high pressure injection, especially for internal combustion engines with self-ignition. In this regard, fuel is supplied by a pre-supply pump in a low-pressure zone and by a high-pressure pump in a high-pressure zone, a so-called Common-Rai1. The pre-fuel pump feeds the fuel, coming from a fuel storage vessel, the tank, into a low pressure zone and is performed in the form of an electric fuel pump. Parallel to the electric fuel pump there is a pressure limiting valve which, when rising above a certain pressure, brings the fuel coming from the low pressure zone back into the vehicle tank. In the high pressure area there is a pressure sensor, which detects the pressure in the Common-Rai1. Furthermore, between the high pressure zone and the vehicle tank there is a pressure regulating valve which, according to a driving current, starting from a certain adjustable pressure, brings the fuel back from the high pressure zone. pressure back into the tank. It is envisaged that the electric fuel pump is regulated in the number of revolutions corresponding to a control signal, in order to harmonize the flow rate to the current requirement of the engine. In the event of a system fault, the pressure relief valve can be used as an emergency valve to quickly lower the pressure in the common rail.

Document DE 19853 823 A1 discloses a method for operating an internal combustion engine, especially of a motor vehicle, in which the fuel is fed into a pressurized accumulator of the internal combustion engine by a first fuel pump, usually operated by electric motor, and a second high pressure pump, usually mechanical. The quantity of fuel supplied can be changed in this regard by means of a corresponding influence of the first fuel pump, which is driven by an electric motor. In this way, the quantity of fuel required from time to time is supplied to the pressurized accumulator. The flow rate of the first fuel pump is piloted through a characteristic field as a function of the quantity of fuel to be injected and / or the number of revolutions of the internal combustion engine and / or the temperature of the intake air and / or the battery voltage. In order to compensate for the tolerances of the different fuel pumps, as well as for modifications due to aging, the possibility of balancing the characteristic range at each starting operation of the internal combustion engine is made public. For balancing purposes, for example, the actual pressure value in the pressurized accumulator is measured and compared with a nominal value of the pressure in the pressurized accumulator, depending on the required amount of fuel. The characteristic range is balanced as a function of the comparison between the determined actual value and the nominal value of the pressure in the pressurized accumulator. The pressure in the pressurized accumulator is detected with 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 returns the excess fuel back into the vehicle tank. The pressure control valve can be opened and closed via an input signal. An electronic control device is also provided, 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. As a result of this measure, the electronic control unit can influence the flow rate of the first fuel pump as well as the pressure in the high-pressure zone via the pressure control valve.

A fuel supply system for an internal combustion engine, especially of a motor vehicle, in which fuel is pumped by means of a pump in an accumulator under pressure and from injection valves is directly injected into the internal combustion engine. The possibilities of operating the pump mechanically, therefore by rigid coupling with the internal combustion engine, or of running the pump in the form of an electric pump, are made public. The overall system, corresponding to the Germanic invention patent application DE 199 03 272.6-13 not yet previously disclosed, has an electric fuel pump, which feeds fuel, coming from a tank, in a low pressure zone. From this low-pressure zone, the fuel is fed, by means of the high-pressure pump, into a pressure zone, respectively in a Common-Rail. From this pressure zone, the fuel is injected directly into the combustion chamber of the internal combustion engine by means of injection valves. In addition to this, a pressure sensor and a pressure control valve are located in the high-pressure zone of the system. Both the electric high-pressure pump as well as the pressure sensor, the injection valves and the pressure control valve are connected to a control device which, inter alia, implements, on the basis of the data provided by the pressure sensor, at least the piloting of the high pressure electric pump, of the injection valves and of the pressure control valve. For the purpose of managing the quantity of fuel supplied, the possibility of regulating the number of revolutions of the electric fuel pump corresponding to the requested flow rate is made public. The piloting of the pressure control valve takes place with different synchronization ratios, which in themselves are constant from time to time, which are selected according to the operating condition, by way of example starting operation, or normal. The peculiarity of the Germanic invention patent application not yet previously made public DE 199 03 272.6-13 is to be seen in the fact that the high pressure pump is configured and dimensioned in such a way that, within a modest time interval, especially within a few revolutions of the internal combustion engine, sufficient pressure is already present in the pressurized accumulator for the injection of the fuel into the combustion chambers of the internal combustion engine.

Advantages of the invention

A fuel supply system for an internal combustion engine, especially of a motor vehicle, comprising at least a combustion chamber, such as a first pump, by means of which the fuel can be fed into a first pressurized zone, at least a second pump , by means of the wing the fuel can be fed, starting from the first pressure zone, in a second pressure zone, at least a pressure accumulator in the second pressure zone, v e injection, by means of which the paper can be injected , starting from the second. a under pressure, directly in the chamber itself or, at least a means that regulates and / or with a pressure and which is arranged in the second a under pressure, where the second pump is in the form of an electric pump, developed with respect to the state of the art due to the fact that the means which regulates and / or with the pressure and the second pump form a constructive unit and / or due to the fact that the means which regulates and / or controls the pressure is integrated in the second pump. The advantages of the ema fuel supply conforming to the invention lie, among other things, in the compact dimensions and the favorable costs for such a system.

A particularly advantageous development of the fuel supply system according to the invention is that the second pump is arranged in a constructively separate manner from the engine block surrounding the combustion chamber. On the one hand, this constructive separation offers advantages when packaging in the engine compartment, which is of great advantage in the case of the construction of a new vehicle. On the other hand, due to the constructively separated arrangement, a thermal decoupling is ensured relative to the engine block that encloses the combustion chamber, which is advantageous especially in hot start situations, given that, after the motor vehicle has stopped hot condition, at least the propellant still in the pump unit will not heat up further.

Advantageously, a device for regulating the number of revolutions is provided for driving the second pump and a control device for controlling and / or regulating the device for regulating the number of revolutions. As a result of this inventive speed control device, the fuel supply system can be operated particularly advantageously, in a demand-controlled and efficient manner, since the speed can be adapted to suit respective requirements of the internal combustion engine. In this regard, a further advantageous development is that the control unit is an internal combustion engine control unit and that this engine control unit is additionally used for driving the means which regulates and / or controls the pressure. The advantage of this configuration lies in the fact that an additional control unit for controlling and / or regulating the speed control device can be dispensed with. This again has a positive effect on space requirements and costs.

The means which regulates and / or controls the pressure is advantageously realized in the form of a pressure regulator and / or a pressure limiting valve and / or a pressure control valve and / or a flow control valve. In combination with this, a pressure sensor is advantageously arranged in the second pressure zone, which, in the context of a preferred development, is arranged in the construction unit formed by the means which regulates and / or controls the pressure and the second pump. . As a result of these developments in accordance with the invention, a constructive unit consisting of pressure generation, pressure detection and pressure influence is obtained, for which a more or less completely self-sufficient system for supply is made available. fuel.

An advantageous development provides that a signal representing a pressure value is transmitted from the pressure sensor to the control device or to the engine control device. In this case, the signal transmission can take place via a direct signal line or via an indirect signal line, here in particular a vehicle bus system (such as a CAN bus).

A preferred development of the fuel supply system provides that at least an ignition device is associated with the combustion chamber, by means of which the fuel in the combustion chamber can be ignited. Advantageous is also a conception of the internal combustion engine such that the fuel can be injected into the combustion chamber, at least in a first type of operation, during a compression phase and in a second type of operation during an intake phase. In particular, the use of direct injection and injection, in the two different types of operation, in combination with the fuel supply system according to the invention gives rise to a conception of the internal combustion engine which particularly allows savings. fuel, save space and is economical.

Other characteristics, possibilities of application and advantages of the invention can be deduced from the following description of examples of embodiment of the invention, which are shown in the figures of the drawing. All the characteristics described or represented in this regard form the subject of the invention, independently or in arbitrary combination, regardless of their grouping in the claims, or their correlation, as well as regardless of their formulation, respectively representation in the description, respectively in the drawing.

Examples of realization

Figure 1 shows a first example of embodiment of the fuel supply system according to the invention e

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

Figure 1 shows a fuel supply system which is intended for use in an internal combustion engine of a motor vehicle. As far as the fuel supply system is concerned, this is a so-called system of the Common-Rai1 type, which is used especially in an internal combustion engine with direct petrol injection (BDE system).

The designation 1 in FIG. 1 characterizes a fuel storage vessel, or tank, in which an electrically operated fuel pump 2 is integrated. Also shown is a central device of the engine (for example MOTRONIC) 3 which, through a control line 4, can regulate and / or control the electric fuel pump 2, by way of example the number of revolutions of the electric pump of the fuel 2. The fuel is conveyed by the electric fuel pump 2, starting from the tank 1, passing through a first pipeline under pressure 5, towards a second pump 6. As regards the second pump 6, it is a high-pressure pump operated electrically, which is for example constituted by the combination of an arbitrary electric motor and a mechanical pump. The high-pressure pump 6 is connected to the motor control unit 3 via a control line 7, whereby an influence on the operating behavior of the high-pressure pump 6 can be exerted by the motor control unit 3 The fuel is put under high pressure by the high-pressure pump 6 and through the high-pressure line 8 it reaches a pressurized accumulator 9, respectively in a Common-Rail. Starting from this pressurized accumulator 9, the fuel is conveyed towards the injection valves 11 via high pressure supplies 10. By means of the injection valves 11, the fuel can be injected directly into the combustion chambers 12 of the internal combustion engine. In the representation of Figure 1, only one combustion chamber 12 is schematically represented. The injection valves 11 are likewise connected, through control lines 13, to the engine control unit 3. Through these control lines 13 from the The injection time and duration of the injection valves 11 can be set individually in each case. A pressure sensor 14 is also fitted in the area of the pressure accumulator 9, which measures the pressure in the pressure accumulator 9. The result of this measurement is fed back to the motor control unit 3 via a signal line 15. Based on the pressure data determined by the pressure sensor 14, the motor control unit 3 can control a means for regulating the pressure and / or for controlling the pressure 16 through a control line 17. The means for regulating the pressure and / or pressure control 16 is, according to the invention, flanged directly on the high-pressure pump 6, or is integrated in the pump 6. In any case, the high-pressure pump 6 and the control means 16 form a constructive unit 21, which can be arranged separately with respect to the engine block enclosing the combustion chamber 12, mentioned here by means of constructive unit 22. The excess fuel ( quantity that overflows) returns, through a duct 24, to the first pressure zone 5, in front of the high-pressure pump 6.

Reference 18 indicates a speed control device which serves to control the high-pressure pump 6, which is connected to the high-pressure pump 6 via the control line 20 for this purpose. of revolutions which are to be controlled by the speed control device 18, are fed to the speed control device 18 via a control line 19 from the motor control unit 3.

Figure 1 also shows a plurality of further lines 23 entering or leaving the engine control unit 3 respectively. These lines 23 symbolize the connections of the engine control unit 3 with the other components of the motor vehicle, which are not shown in the representation in figure 1.

As means 16 which regulate and / or control the pressure, for example, a pressure regulator and / or a pressure limiting valve and / or a pressure control valve and / or a flow control valve can be used. . If, in the case of a pressure regulator, a mechanical regulator (with integrated mechanical spring) is used, then it is possible to dispense with the pressure sensor 14. If a pressure limiting valve is used, a control valve control valve or a flow control valve, which can be controlled electronically, this actuation takes place as a function of the data supplied by the pressure sensor 14 via the motor control unit 3.

The fuel supply system according to the invention also includes the fact that the control unit 3 shown is not the control unit of the internal combustion engine, but an arbitrary additional control unit which can, by way of It is also possible, for example, to be integrated in the construction unit 21. It is also possible that the functions of the motor control unit 3 shown in Fig. 1 are distributed in a fully variable manner to the motor control unit and to a further control unit . There is also the possibility that the speed control device 18 is integrated into the construction unit 21. In this way, the entire construction unit 21 could be driven via pure pilot lines (therefore without noteworthy power transmission) by the Engine control unit 3. A further possibility is that the speed control device 18 (including the final driving stages) is integrated in the control unit or in the engine control unit.

One of the great advantages of the constructive separation between the high-pressure pump 6 and the motor block unit 22 consists in the thermal decoupling of the units. In the case of the otherwise usual flanging of a mechanical high-pressure pump on the engine block, due to the effect of the thermal coupling, the fuel still in the pump is strongly heated when the vehicle is stopped with a hot engine. In such a situation, on the occasion of a subsequent hot start, problems can occur, with the formation of steam bubbles, and therefore malfunctions and / or ignition dystonia. Another major advantage of constructive separation lies in the more flexible distribution of components in the engine compartment. The volume available under the engine hood can thus be used more flexibly.

The signal supplied by the pressure sensor 14, which in arbitrary form represents a pressure value, is transmitted, as shown in FIG. 1, to the engine control unit 3 via a signal line 15. In this regard, within the scope of Fuel system according to the invention also includes the fact that no direct signal line is used for signal transmission, but an indirect signal line, such as a vehicle bus system (especially a CAN bus). All other signal and control lines shown in FIG. 1 can likewise be implemented both via direct signal lines as well as via an indirect connection via a bus system (eg CAN bus).

Figure 2 shows a second example of embodiment of the fuel supply system according to the invention. In the representation of Figure 2, the elements which correspond to those of Figure 1 are characterized by the same markings. Therefore, below we enter only into the merits of the differences between Figure 2 and Figure 1. The substantial difference between Figure 2 and Figure 1 lies in the fact that the pressure sensor 14 'is also integrated in the constructive unit 21' and by way of example, it is applied to the high-pressure pump 6 or integrated into the high-pressure pump 6. In this case too, the signals representing a pressure are transmitted to the control device of the motor 3 via a signal line 15 '. The resulting engine block unit 22 'is characterized, corresponding to Figure 1, with a dashed line.

In the context of the fuel supply system according to the invention, the engine control unit 3 exerts an influence on the fuel supply in a different way. Assuming that a determination is made in the engine control unit based on the pre-existing operating conditions and the requirements of the driver of the vehicle as to how much fuel is required by the internal combustion engine, a pilot control is on the one hand possible due to the fact that the electric fuel pump 2 is regulated in its number of revolutions via a control line 4. As a further component of the influence exerted, the means 16 is available which regulates and / or controls the pressure and which can be controlled by the motor control unit 3 via the control line 17. Finally, the speed control device 18 is still available, through which the high-pressure pump 6 can be controlled in the number of laps. All these measures in combination result in a fuel supply system which ideally works in a demand-driven manner and at the same time has a particularly low self-energy requirement. The possible fuel savings achievable through the use of a fuel supply system managed according to the requirement is in the order of magnitude of 1 up to 2% of consumption compared to a conventional (unregulated) fuel supply system. vehicle fuel assembly.

Particularly in combination with use in the case of direct petrol injection, particularly high fuel consumption benefits are achieved. Characteristic for direct petrol injection is the fact that the fuel can be injected into the combustion chamber, at least in a first type of operation, during a compression phase and in a second type of operation during an intake phase. The second type of operation, during which it is injected in the intake phase, corresponds approximately to the homogeneous operation of a motor vehicle, in which the power is primarily managed through the air conveyed to the combustion chamber. In this case, power management takes place via the throttle valve. In the first type of operation, on the other hand, it drives more or less in a non-throttled way and power is primarily influenced by the quantity of fuel injected into the combustion chamber. Especially in this type of operation, which is also called stratified operation, the fuel requirement of the internal combustion machine is low and the speed of the high-pressure pump 6 can be lowered.

Another major advantage of the constructive unit 21, respectively 21 'lies in the fact that it is more easily possible for the various vehicle manufacturers to adapt existing internal combustion engines to a system with direct petrol injection (BDE system).

Claims (1)

Claims 1.- Fuel supply system for an internal combustion engine, especially of a motor vehicle, comprising at least one combustion chamber (12) comprising at least a first pump (2), by means of which the fuel can be fed into a first pressure zone (5), comprising at least a second pump (6), by means of which the fuel coming from the first pressure zone (5) can be fed into a second pressure zone (8), comprising at least a pressurized accumulator (9) in the second zone in pressure (8), comprising injection valves (11), by means of which the fuel coming from the second pressure zone (8, 9) can be injected directly into the combustion chamber (12), comprising at least a means (16) which regulates and / or controls a pressure and which is arranged in the second pressure zone (8), where the second pump (6) is made in the form of an electric pump, characterized by the fact that the means (16) which regulates and / or controls the pressure and the second pump (6) form a constructive unit (21, 21 '), and / or the means (16) which regulates and / or controls the pressure is integrated in the second pump (21, 21 '). 2.- Fuel supply system according to Claim 1, characterized in that the second pump (6) is arranged in a constructively separate manner from the engine block (22) which encloses the combustion chamber (12). 3.- Fuel supply system according to Claim 1, characterized by the fact that there is a device for regulating the number of revolutions (18) adapted to drive (20) the second pump (6), and by the fact that a control unit (3) for piloting (19) and / or for regulating the speed control device (18). 4.- Fuel supply system according to Claim 1, characterized in that the control device (3) is a control device (3) of the internal combustion engine, and in that a control device (19) of the medium (18) which regulates and / or controls the pressure takes place via the engine control apparatus (3). 5.- Fuel supply system according to Claim 1, characterized in that the means (16) which regulates and / or controls the pressure is a pressure regulator and / or a pressure limiting valve and / or a control valve pressure and / or a flow control valve. 6.- Fuel supply system according to Claim 1, characterized in that at least one pressure sensor (14) is arranged in the second pressure zone (8, 9). 7.- Fuel supply system according to Claim 6, characterized in that the pressure sensor (14 ') is arranged in the constructive unit (21'), consisting of the means which regulates and / or controls the pressure and the second pump (6). 8.- Fuel supply system according to claims 3 and 6, characterized in that a signal, representing a pressure value, can be transmitted (15, 15 ') from the pressure sensor (14, 14') to the device control (3). 9.- Fuel supply system according to Claim 8, characterized in that a direct signal line (14, 14 ') or an indirect signal line, via a vehicle bus system, are provided for the transmission of the signal. especially a CAN bus. 10.- Fuel supply system according to Claim 1, characterized in that at least one ignition device is associated with the combustion chamber (12), by means of which the fuel in the combustion chamber (12) can be ignited. 11.- Fuel supply system according to Claim 1, characterized by the fact that the fuel can be injected into the combustion chamber (12), at least in a first type of operation, during a compression phase and in a second type of operation during an aspiration phase.