EP1327766A2 - Method, computer programme and control and/or regulation device for operating an internal combustion engine, and internal combustion engine - Google Patents

Abstract

The engine has a piston pump (18) as a fuel pump with at least one transport chamber (38). The method involves using number of engine operating ranges and separating the transport chamber from a low pressure region (16) with a valve (44) for a defined period every defined number of transport strokes in a first operating range and at different intervals in a different operating range. Independent claims are also included for the following: a computer program and a control and/or regulation device for operating an internal combustion engine.

Description

State of the art

The invention initially relates to a method for operating an internal combustion engine in which a fuel pump from an output shaft of the internal combustion engine and the Fuel from the fuel pump into a fuel rail is promoted, of which he has at least one Fuel injection device in at least one combustion chamber arrives, and in which the amount of fuel pump in through the fuel manifold a valve device is set which a Pressure side of the fuel pump at least temporarily with one Can connect and separate the low pressure area.

Such a method is known from DE 195 39 885 A1. In this is a fuel supply system for one Internal combustion engine described with gasoline direct injection. A first, electrically driven fuel pump delivers the fuel from a fuel reservoir through a Fuel connection to a second, from the Internal combustion engine mechanically driven fuel pump. The second fuel pump in turn delivers the fuel via a fuel rail ("Rail") to several Fuel injection valves. The number of fuel injectors is equal to the number of cylinders Internal combustion engine. The fuel supply system is like that that the fuel injectors built the fuel Inject directly into the combustion chambers of the internal combustion engine.

Since the second fuel pump mechanically with a Output shaft of the internal combustion engine is coupled works the second fuel pump proportional to the speed of the Output shaft of the internal combustion engine. This speed of the Output shaft can, depending on the current operating condition the internal combustion engine, be very different. In the The output shaft can be, for example, a crankshaft or act on a camshaft of the internal combustion engine.

To from the second fuel pump to the fuel rail amount of fuel delivered regardless of To be able to set the speed of the internal combustion engine is a electromagnetic pressure switching valve provided. With this can a pressure side of the second fuel pump with a Low pressure side of the second fuel pump can be connected. In another switching position of the pressure switching valve this connection is broken. Is the connection between the Opened high pressure side and the low pressure side, which rolls second fuel pump the fuel from its high pressure side to the low pressure side. A promotion in the fuel manifold therefore does not take place.

In order to deliver a small amount of fuel, this is allowed Volume control valve during a delivery stroke of the Fuel pump only for a very short period of time be closed. Due to the inertia of the Valve element and minimal for the reduction of the magnetic field required time period, the valve element does not open as fast as you want. Very small amounts can therefore only can be realized with comparatively large valve seats.

However, these require a correspondingly large dimension Magnetic circuit, which in turn is relatively slow.

The present invention has for its object a method of type mentioned at the outset in such a way that robust components can be used, which take a long time Have lifespan, and that on the other hand the Setting range from the fuel pump to the fuel rail delivered fuel quantity is as large as possible. In addition, that exact amount of fuel should be as possible can be promoted, which is injected, and the Pressure in the fuel rail should be as accurate as possible can be adjusted.

This task is carried out in a method of the type mentioned at the beginning Art solved in that a piston pump as a fuel pump is used with at least one funding room that a Plurality of operating areas 1, ..., n der Internal combustion engine is provided, and that at least at times in a first operating area of the Internal combustion engine the delivery room during every c1-th Production hubs and in an nth operating area of the Internal combustion engine during every cnth delivery stroke through the Valve device for a certain period of Low pressure range is separated, where: c1, ..., cn are differently.

Advantages of the invention

The use of a piston pump as a fuel pump has the Advantage that very high pressures in the fuel rail with little wear on the fuel pump are achievable. A piston pump is very simple and is therefore inexpensive. This applies in particular to the use a 1-cylinder piston pump.

Despite the use of a piston pump, the The method according to the invention, depending on the requirements, is very large, but also small and very small amounts of fuel to the fuel manifold be promoted. An overpressure return from the fuel rail can thus be relatively small be dimensioned, and that for driving the Fuel pump energy is when little Fuel can be fed into the fuel rail should only be relatively minor. That is the following thought based on:

A piston pump works discontinuously, i.e. it can only during a fuel pump delivery stroke Fuel manifold are pressed. Should be the maximum Amount of fuel delivered by the fuel pump, the valve device remains during the entire delivery stroke closed. The fuel delivery volume is thus fully pressed into the fuel rail. Should a lower amount of fuel in the fuel rail will be funded during a funding stroke the valve device opened. Once the valve device is open, the remaining funding volume is no longer into the fuel rail, but into the Low pressure area promoted.

The promotion of small and very small quantities is problematic of fuel into the fuel rail. Such Small volume production is desirable, for example, if the internal combustion engine and the one coupled to it Turn the fuel pump at high speed However, the internal combustion engine is only operated with a low load and therefore only a little fuel from the fuel rail gets into the combustion chambers. In this case with a delivery stroke of the fuel pump only one extreme small amount of fuel in the fuel rail be promoted.

According to the invention, this is implemented as follows:

The internal combustion engine is in an operating range operated in which the fuel pump is only a small one Fuel quantity should promote, and is a relatively seen high engine speed before, the Valve device not for every delivery stroke, but only for controlled every cnth delivery stroke. In this way, the Period during which the valve device is closed, be longer than in the case where the valve device is closed during each delivery stroke. simultaneously is however also the promotion of very small quantities by the Fuel pump in such a operated Internal combustion engine possible. This is through only "Software engineering" measures possible.

A less frequent activation of the valve device is selected when displaying the desired delivery rate due to the system-related limits of the valve device is no longer possible. These are system boundaries then reached when a safe closing of the Valve device due to the short available standing time is no longer guaranteed. The control the valve device must be done so often that the maximum permissible pressure pulsations on the one hand in Low pressure area and on the other hand in the fuel rail not be exceeded.

Basically, ci (i = 1 to n) is any natural number including 0 can assume. With ci = 0 that remains Volume control valve always open, so it takes place at all no funding instead. With ci = 1 takes place with each delivery stroke a funding instead. At ci> 1 funding is granted, but not with each delivery stroke.

Advantageous developments of the invention are in Subclaims specified.

First, it is proposed that two operating areas of the Internal combustion engine are provided and that in the first Operating range of the internal combustion engine in the delivery room every delivery stroke and in the second operating range of Internal combustion engine of the delivery chamber with every third delivery stroke separated from the low pressure area by the valve device becomes. The advantage of this training lies in the one simple software feasibility, since only two Operating areas must be taken into account. On the other hand are only possible with one control of the valve device third delivery stroke also such very small delivery quantities Fuel pump representable, as they are especially at high Speeds and low load of an internal combustion engine be desired.

Such a method is particularly preferred, in which two neighboring operating areas overlap so that a Hysteresis area is formed. This avoids that when the internal combustion engine is operating in the limit range a constant between two neighboring operating areas Switching from one control type of the valve device to a different type of control takes place.

It is also proposed that the operating areas of the Internal combustion engine at least through a speed range a crankshaft of the internal combustion engine and by one Area of an injection from the fuel injector to be introduced into a combustion chamber Fuel mass or through a range of one in the Fuel manifold prevailing fuel pressure are defined. With these parameters and the known ones System properties of the fuel pump are easy define those areas in which the control of the Valve device for example with each delivery stroke or at every third delivery stroke.

The invention also relates to a computer program which for Carrying out the above procedure is appropriate if it is on running on a computer. It becomes special preferred if the computer program is on a memory, is stored in particular on a flash memory.

The invention further relates to a control and / or regulating device for operating an internal combustion engine. With such a Control device is preferred when on it Computer program of the above type is stored.

Part of the invention is also an internal combustion engine, with a Fuel pump, which is driven by an output shaft of the Internal combustion engine is driven, with a fuel rail, into which the fuel pump delivers, with a Fuel injector attached to the fuel rail is connected with a combustion chamber in the the fuel injector injects the fuel, and with a valve device which a pressure side of the Connect fuel pump to a low pressure area and from can separate this.

Such an internal combustion engine is also from the
DE 195 39 885 A1 known. So that such an internal combustion engine is as robust as possible and can be manufactured inexpensively, it is proposed that the fuel pump comprise a piston pump with at least one delivery chamber and that the internal combustion engine comprise a control and / or regulating device which comprises a plurality of operating areas 1, ... , n of the internal combustion engine of the internal combustion engine and which controls the valve device in such a way that, at least temporarily in a first operating range of the internal combustion engine, the delivery chamber for every c1th delivery stroke and in an nth operating range of the internal combustion engine for every cnth delivery stroke through the valve device for a certain period of time is separated from the low pressure range, where: c1, ..., cn are different.

In such an internal combustion engine, it is also advantageous if they are a control and / or regulating device includes the above type.

drawing

Fig. 1:

eine Prinzipdarstellung einer Brennkraftmaschine mit einer Kraftstoffpumpe und einem Mengensteuerventil;

Fig. 2:

eine detailliertere Darstellung der Kraftstoffpumpe und des Mengensteuerventils von Fig. 1 während eines Saughubes;

Fig. 3:

eine Darstellung ähnlich Fig. 2 zu Beginn eines Förderhubes;

Fig. 4:

eine Darstellung ähnlich Fig. 2 gegen Ende eines Förderhubes;

Fig. 5:

ein Diagramm, in dem zwei Betriebsbereiche der Brennkraftmaschine von Fig. 1 abhängig von dem von der Kraftstoffpumpe zu fördernden Kraftstoff-Mengenstrom und von der Drehzahl einer Kurbelwelle der Brennkraftmaschine dargestellt sind;

Fig. 6:

ein Diagramm, in dem die Betriebsbereiche der Brennkraftmaschine von Fig. 1 abhängig von einem Druck in einer Kraftstoff -Sammelleitung und der Drehzahl einer Kurbelwelle der Brennkraftmaschine dargestellt sind.

Fig. 7:

ein Diagramm, in dem der Hub eines Kolbens der Kraftstoffpumpe von Fig. 1 über der Zeit im ersten Betriebsbereich der Brennkraftmaschine dargestellt ist;

Fig. 8:

ein Diagramm, in dem der Steuerstrom des Mengensteuerventils von Fig. 1 in dem ersten Betriebsbereich der Brennkraftmaschine dargestellt ist;

Fig. 9:

ein Diagramm ähnlich Fig. 7, in dem der Hub eines Kolbens der Kraftstoffpumpe von Fig. 1 über der Zeit im zweiten Betriebsbereich der Brennkraftmaschine dargestellt ist; und

Fig. 10:

ein Diagramm ähnlich Fig. 8, in dem die Bestromung des Mengensteuerventils von Fig. 1 in dem zweiten Betriebsbereich der Brennkraftmaschine dargestellt ist.

A particularly preferred exemplary embodiment of the invention is explained in detail below with reference to the accompanying drawing. The drawing shows:

Fig. 1:

a schematic diagram of an internal combustion engine with a fuel pump and a quantity control valve;

Fig. 2:

a more detailed representation of the fuel pump and the quantity control valve of Figure 1 during a suction stroke.

Fig. 3:

a representation similar to Figure 2 at the beginning of a delivery stroke.

Fig. 4:

a representation similar to Figure 2 towards the end of a delivery stroke.

Fig. 5:

a diagram in which two operating ranges of the internal combustion engine of FIG. 1 are shown depending on the fuel flow to be delivered by the fuel pump and on the speed of a crankshaft of the internal combustion engine;

Fig. 6:

a diagram in which the operating ranges of the internal combustion engine of FIG. 1 are shown depending on a pressure in a fuel manifold and the speed of a crankshaft of the internal combustion engine.

Fig. 7:

a diagram in which the stroke of a piston of the fuel pump of Figure 1 is shown over time in the first operating range of the internal combustion engine;

Fig. 8:

a diagram in which the control flow of the quantity control valve of FIG. 1 is shown in the first operating range of the internal combustion engine;

Fig. 9:

7 shows a diagram similar to FIG. 7, in which the stroke of a piston of the fuel pump from FIG. 1 is shown over time in the second operating range of the internal combustion engine; and

Fig. 10:

a diagram similar to FIG. 8, in which the energization of the quantity control valve of FIG. 1 is shown in the second operating range of the internal combustion engine.

Description of the embodiment

In Fig. 1, an internal combustion engine carries this overall Reference numeral 10. It comprises a fuel tank 12, from which is an electrically driven fuel pump 14 Promotes fuel in a low pressure fuel line 16. This leads to a high-pressure fuel pump 18 The high-pressure fuel line 20 advances the fuel to a fuel manifold 22. In this is the Fuel can be stored under high pressure. To the fuel rail 22 are multiple fuel injectors 24 connected. These inject the Fuel directly into combustion chambers 26. By burning of the fuel in the combustion chambers 26 becomes a crankshaft 28 set in rotation. Only symbolically in FIG. 1 Mechanical coupling 30 shown is the high pressure fuel pump 18 driven by the crankshaft 28.

As can be seen in particular from FIGS. 2-4, acts high-pressure fuel pump 18 is a 1-cylinder piston pump. This is from one to one Drive cam 32 arranged a piston 34 into a shaft 33 Moved back and forth. The piston 34 is in one Housing 36 out. It delimits a funding area 38 Inlet valve 40 may be the delivery chamber 38 with the low pressure fuel line 16 can be connected. Intake valve 40 is designed as a spring-loaded check valve. About one Exhaust valve 42 can the delivery chamber 38 with the high pressure fuel line 20 are connected. Even with the exhaust valve 42 is a spring-loaded check valve.

The delivery chamber 38 can also be operated via a quantity control valve 44 to be connected to the low pressure fuel line 16. The volume control valve 44 is a 2/2-way valve. In the open rest position it is from one Spring 46 acted (in a not shown Embodiment is the opening of the Volume control valve only via the pressure in the delivery chamber). In the closed switch position is from a brought electromagnetic actuator 48. This includes one connected to a valve element 50 Magnet armature 52, which is surrounded by a magnet coil 54.

The solenoid 54 is from an output stage, not shown energized. The final stage is in turn controlled by a control and Control device 56 controlled. The control and regulating device 56 receives signals from a speed sensor 58 which the Speed of crankshaft 28 of internal combustion engine 10 taps. Furthermore, the control and regulating device 56 connected on the input side to a pressure sensor 60 which detects the prevailing pressure in the fuel rail 22 and corresponding signals to the control and regulating device 56 passes.

The basic principle of setting the high pressure fuel pump 18 fuel quantity delivered is now under 2 - 4 explains:

During the suction stroke shown in Fig. 2 the moves Piston 34 down, so fuel over that Inlet valve 40 flows into the delivery chamber 38. After this The piston 34 moves to the bottom dead center back up (Fig. 3). During piston 34 suction stroke the solenoid 54 of the quantity control valve 44 is energized, so this at the latest when reaching the lower one Dead center of the piston 34 closes. Intake valve 40 also closes.

When the opening pressure during the delivery stroke of the piston 34 of the outlet valve 42 in the delivery space 38 is exceeded, open this. This allows the fuel to enter the fuel rail 22 are pressed. Should during a Delivery stroke of the piston 34 to deliver fuel into the Fuel manifold 22 are terminated, the Energizing the solenoid 54 of the quantity control valve 44 ended, so that this again in its open rest position on. This is shown in FIG. 4. The fuel can thus from the delivery chamber 38 via the open one Flow control valve 44 into the low pressure fuel line 16 escape. The outlet valve 42 also closes accordingly.

The maximum conveyable during a delivery stroke of the piston 34 The amount of fuel is essentially independent of the Speed of the crankshaft 28 and the related Duration of a delivery stroke. However, the absolute duration decreases a delivery stroke inversely proportional to the speed of the Crankshaft 28. Should now, for example, only a third of the maximum possible delivery rate during a delivery stroke of of the fuel pump 18, this means that the quantity control valve 44 approximately after one Third of the stroke of the piston 34 must open ("approximately" because the delivery rate is not proportional to the delivery stroke and for the control duration of the quantity control valve). The Period of time from the bottom dead center of the piston 34 in which the quantity control valve 44 closes at the latest by required opening time of the quantity control valve 44 passes, is, at an assumed same to promoting fuel quantity, at high speed shorter than at low speed.

In order for the internal combustion engine 10 shown in FIG entire speed range of the crankshaft 28 large Amounts of fuel as well as small and very small amounts of fuel to be able to promote by the high pressure fuel pump 18 depending on the operating range in which the internal combustion engine 10 works, the delivery room 38 during each ci-th delivery stroke for a certain period by the quantity control valve 44 of the low pressure fuel line. The following applies in present embodiment in a first Operating range of the internal combustion engine 10 ci = 1 (promotion with each delivery stroke) and in a second operating range Internal combustion engine 10 ci = 3 (promotion every third Delivery stroke). This is now shown in FIGS. 5 to 10 explains:

Parameters are stored in a memory in the control and regulating device 56 filed through the two operating areas of the Internal combustion engine 10 are defined. With these parameters on the one hand it is a speed nmot the Crankshaft 28 of the internal combustion engine 10, on the other hand around the from the fuel injector 24 at one Injection fuel mass to be injected m and finally still the current in the fuel rail 22 prevailing fuel pressure pr. 5 and 6 wear the two operating areas, reference numerals 62 and 64.

In the operating area 62, that is to say overall lower and medium speed nmot and at medium to high fuel mass to be injected m or a medium one to high pressure pr in the fuel rail 22 the solenoid 54 just before the start of each delivery stroke for energized for a certain period of time. This is in Figures 7 and 8. This ensures that Volume control valve 44 at the beginning of the delivery stroke really closed is. A conveying stroke carries this in Fig. 7 Reference numeral 66, the corresponding current pulses in FIG. 8 the reference numerals 68. This means that the conveying space 38 during each delivery stroke 66 for a certain period of the low-pressure fuel line 16 is separated, that is, at each delivery stroke 66, a delivery of fuel takes place.

It should be noted that the energization of the Volume control valve 44 may already be immediately before the start a conveyor stroke 66 can also be ended again. at Appropriate timing is still under due to inertia, a delayed opening immediately after the start of the funding stroke. Such Shift of the control end of the quantity control valve 44 enables dismantling of the built up by the current supply Residual magnetism, which after switching off the Volume control valve 44 is present.

In the operating area 64, on the other hand, that is, at medium to high Speed nmot, with medium to low injection Fuel mass m and medium to low Fuel pressure pr in the fuel rail 22 is the magnetic coil 54, on the other hand, only every third delivery stroke 66 energized. This is shown in FIGS. 9 and 10. Both this remains between the two conveying strokes 66 Volume control valve 44 in this operating area 64 of Internal combustion engine 10 in its open rest position. A Delivery of fuel by the high pressure fuel pump 18 does not take place in these two conveying strokes 66. In this way it is possible to nmot even at high speed only a very small amount of fuel from the high pressure fuel pump 18 per unit of time to promote without the Minimum possible closing time of the volume control valve 44 is undercut.

To prevent the operation of the Internal combustion engine 10 in the border area between the two Operating areas 62 and 64 constantly between those in FIG. 8 energization 68 of the magnet coil 54 shown at each Delivery stroke 66 and the energization 68 shown in FIG. 10 the solenoid 54 back and forth only every third delivery stroke 66 is switched, the operating areas 62 and 64 in Control and regulating device 56 stored so that they are overlap. This creates a hysteresis area 70. A switchover of the control of the quantity control valve 44 from the control shown in FIG. 8 to that in FIG. 10 shown control takes place only when the Operating area 62 is left (arrow 72 in Figs. 5 and 6). Switching from that shown in Fig. 10 Control on the control of the Quantity control valve 44 is only carried out when the Operating area 64 is left (arrow 74 in FIGS. 5 and 6).

At this point it should be noted that the Realization of even the smallest flow rates at high speeds nmot of the internal combustion engine 10 exclusively by a appropriate software programming of the control and Control device 56 is made possible. Whether the internal combustion engine 10 currently in operating area 62 or in operating area 64 works by comparing the speed sensor 58 and signals provided by the pressure sensor 60 as well as in the Control and regulating device 56 depending on the desired load determined amount of fuel to be injected with the Control and regulating device 56 stored parameter areas certainly.

Claims (9)

Method for operating an internal combustion engine (10), in which a fuel pump (18) is driven by an output shaft (28) of the internal combustion engine (10) and the fuel is conveyed by the fuel pump (18) into a fuel collecting line (22), from which it reaches at least one combustion chamber (26) via at least one fuel injection device (24), and in which the quantity (m) of fuel delivered by the fuel pump (18) into the fuel collecting line (22) through a valve device (44) is set, which can connect and disconnect a pressure side (38) of the fuel pump (18) at least temporarily to a low-pressure region (16), characterized in that a piston pump (18) with at least one delivery chamber (38) is used as the fuel pump, that a plurality of operating areas 1, ..., n (62, 64) of the internal combustion engine (10) is provided, and that at least temporarily in a first operating area (62) of the internal combustion engine Motor (10) the delivery chamber (38) during each c1-th delivery stroke (66) and in an n-th operating area (64) of the internal combustion engine (10) during every cn-th delivery stroke (66) by the valve device (44) for one certain duration is separated from the low-pressure area (16), where: c1, ..., cn are different. A method according to claim 1, characterized in that two operating areas (62, 64) of the internal combustion engine (10) are provided and that in the first operating area (62) of the internal combustion engine (10) the delivery chamber (38) with each delivery stroke (66) and in the second operating area (64) of the internal combustion engine (10) the delivery chamber (38) is separated from the low-pressure area (16) by the valve device (44) on every third delivery stroke (66). Method according to one of claims 1 or 2, characterized in that two adjacent operating areas (62, 64) overlap so that a hysteresis area (70) is formed. Method according to one of the preceding claims, characterized in that the operating ranges (62, 64) of the internal combustion engine (10) at least by a speed range (nmot) of a crankshaft (28) of the internal combustion engine (10) and by a range during an injection of the Fuel injection device (24) in a combustion chamber (26) to be introduced fuel mass (m) or by a range of a prevailing in the fuel manifold (22) fuel pressure (pr). Computer program, characterized in that it is suitable for carrying out the method according to one of the preceding claims if it is executed on a computer. Computer program according to claim 5, characterized in that it is stored on a memory, in particular on a flash memory. Control and / or regulating device (56) for operating an internal combustion engine (10), characterized in that it comprises a memory on which a computer program according to one of claims 5 or 6 is stored. Internal combustion engine (10), with a fuel pump (18) which is driven by an output shaft (28) of the internal combustion engine (10), with a fuel collecting line (22) into which the fuel pump (18) delivers, with a fuel injection device (24), which is connected to the fuel collecting line (22), with a combustion chamber (26) into which the fuel injection device (24) injects the fuel, and with a valve device (44), which has a pressure side (34) the fuel pump (18) can connect to and separate from a low-pressure region (16), characterized in that the fuel pump comprises a piston pump (18) with at least one delivery chamber (38), and in that the internal combustion engine (10) has a control and / or or control device (56) which recognizes a plurality of operating areas 1, ..., n (62, 64) of the internal combustion engine (10) and which controls the valve device (44) in such a way that at least temporarily in a first operation bsbereich (62) of the internal combustion engine (10) the delivery chamber (34) with every c1-th delivery stroke (66) and in an n-th operating area (64) of the internal combustion engine (10) with every cn-th delivery stroke (68) through the valve device (44) is separated from the low-pressure region (16) for a certain period of time, where: c1, ..., cn are different. Internal combustion engine (10) according to claim 8, characterized in that it comprises a control and / or regulating device (56) according to claim 7.

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