JP2003097379A - Operating method of internal combustion engine for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate whether the pressure drop in a high-pressure accumulator is caused by a defect in a low-pressure area, or by a defect in a high-pressure area in an internal combustion engine of the type in which the fuel is fed from a metering unit (15) to a high-pressure pump (16), and further fed from the high-pressure pump (16) to the accumulator (17), and the fuel fed from the metering unit (15) to the high-pressure pump (16) is controlled according to the maximum feed capacity of the high-pressure pump (16). SOLUTION: When the pressure in the accumulator (17) is dropped by a control device (20), the fuel is fed from the metering unit (15) over the limit, and then, if the pressure in the accumulator (17) is raised, a defect in the upstream side of the high-pressure pump (16), i.e., in the low-pressure area is estimated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel which is supplied from a metering unit to a high-pressure pump, is delivered from the high-pressure pump into a pressure accumulator, and the fuel supplied from the metering unit to the high-pressure pump is a high-pressure pump. In particular, it relates to a method for driving an internal combustion engine of a motor vehicle which is limited according to the maximum delivery capacity, and more particularly to an internal combustion engine and a control device for an internal combustion engine of a corresponding type.

[0002]

In the presence of defects, for example when the filter is contaminated, the pre-delivery pressure required for the maximum delivery capacity of the high-pressure pump is no longer available. This ultimately results in the pressure in the high pressure accumulator decreasing. However, this kind of pressure drop can also occur, for example, because the injection valve is not completely closed. Therefore, it is not possible to determine whether the pressure drop in the high pressure accumulator is due to a defect in the low pressure region or due to a defect in the high pressure region.

[0003]

An object of the present invention is to detect whether there is a defect in a low pressure region or a defect in a high pressure region in the above-mentioned case.
Among other things, it is to provide a method of driving an internal combustion engine of an automobile.

[0004]

The above-mentioned problems are solved by the present invention.
Fuel is supplied from the metering unit to the high-pressure pump, is delivered from the high-pressure pump into the accumulator, and the fuel supplied from the metering unit to the high-pressure pump is limited according to the maximum delivery capacity of the high-pressure pump In the method of driving an internal combustion engine, if the pressure in the accumulator drops, fuel is supplied from the metering unit beyond the limit, and if the pressure in the accumulator subsequently rises, it is estimated that there is a defect in the upstream region of the high-pressure pump. Will be solved. In the case of internal combustion engines and control devices of the type mentioned above, the abovementioned problems are correspondingly solved in the present invention.

[0005]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the metering unit is opened beyond the limits set on itself. This ultimately becomes a virtual shift in the maximum delivery capacity of the high pressure pump. At this time, if the defect exists in the low pressure region,
The measures described above make it possible again to supply more fuel from the metering unit to the high-pressure pump, so that the high-pressure pump can again deliver the fuel into the accumulator in accordance with its maximum delivery capacity. become. The pressure in the accumulator rises again, from which it can be assumed that there is a defect in the low pressure region.

Therefore, overall, the method of the present invention can determine the presence of defects in the low pressure region. In this case, the method according to the invention does not require any additional components and can be carried out simply and quickly.

In a preferred development of the invention, it is presumed that there is a defect in the region of the high-pressure pump or in the downstream region of the high-pressure pump if no pressure rise occurs in the pressure accumulator.

Of particular importance is that the method of the present invention is implemented in the form of a computer program.
This computer program is provided especially for a control device for an internal combustion engine of a motor vehicle. This computer program has the following program code. That is, the program code is suitable for performing the method of the present invention when executed on a computer. Furthermore, this program code can be stored on a computer-readable data carrier, for example a so-called flash memory. In these cases,
The invention is realized by a computer program, which is the subject of the invention.

[0009]

Other features, means of application and advantages of the invention are:
It can be understood from the following description of the embodiments of the present invention. This embodiment is shown in the individual figures.

FIG. 1 shows a fuel supply system 10 for an internal combustion engine.
Is shown. The fuel supply system 10 is usually called a common rail system, and is suitable for directly injecting fuel into a combustion chamber of an internal combustion engine under high pressure.

This fuel is sucked from the fuel tank 11 through the first filter 12 by the pre-delivery pump 13.
As the pre-delivery pump 13, for example, an electric fuel pump can be used.

The fuel sucked by the pre-delivery pump 13 is delivered to the metering unit 15 via the second filter 14. As the metering unit 15, for example, an electromagnetically controlled proportional valve is used.

A high-pressure pump 16 is installed after the metering unit 15. Generally, a mechanical pump is used as the high pressure pump 16, and the mechanical pump is driven by an internal combustion engine.

The high-pressure pump 16 is connected to a pressure accumulator 17, which is often also called a rail. The pressure accumulator 17 is connected to the injection valve 21 via a fuel pipe. Fuel is injected into the combustion chamber of the internal combustion engine via the injection valve 21.

A pressure adjusting valve 18 is connected to the pressure accumulator 17, and this pressure adjusting valve is connected to the outlet side of the fuel tank 11. The pressure regulating valve 18 may be, for example, an electrically driven solenoid valve.

Further, the pressure sensor 19 may be provided so as to be connected to the pressure accumulator 17.

A controller 20 is provided to which a plurality of input signals are applied. These input signals can be the engine speed N of the internal combustion engine or the engine temperature T of the internal combustion engine. Similarly, the pressure inside the fuel pressure accumulator 17 measured by the pressure sensor 19 can be used.

Depending on the input signal, the controller 20 produces a plurality of output signals. These output signals are, for example, signals for controlling the pre-delivery pump 13, or signals for controlling the metering unit 15, or the pressure regulating valve 18.
Can be a signal for controlling.

The fuel supply system 10 is illustrated in FIG. 1 and operates as follows.

The fuel present in the fuel tank 11 is sucked by the pre-delivery pump 13 and delivered to the metering unit 15. The pressure in this region of the fuel supply system 10, also referred to as the pre-delivery pressure, is typically in the range of about 1-3 bar. Therefore, this region is also referred to as the low pressure region. The aforementioned areas can be monitored here and / or controlled and / or regulated here by means of further valves not shown in FIG.

From the metering unit 15, the amount of fuel to be injected into the combustion chamber of the internal combustion engine is further sent out to the high pressure pump 16 via the injection valve 21 based on the instantaneous driving state of the internal combustion engine. The quantity of fuel supplied from the metering unit 15 to the high-pressure pump 16 is in this case called the delivery quantity.

Subsequently, the fuel to be jetted from the high-pressure pump 16 is sent to the fuel pressure accumulator 17, from which the injection valve 2 is injected.
1 is injected into each combustion chamber of the internal combustion engine. The pressure in the accumulator 17 used to inject will be about 1600 bar. The amount of fuel supplied from the injection valve 21 to the combustion chamber is called the injection amount in this case.

As mentioned above, the pressure regulating valve 18 is used to limit pressure during operation of the internal combustion engine.
This means that the pressure control valve 18 is controlled to open when the pressure in the pressure accumulator 17 reaches a predetermined pressure. In this way, the pressure in the pressure accumulator 17 is prevented from rising above a predetermined value.

Especially at low fuel temperatures, metering of the fuel to be injected is only possible with a limited capacity via the metering unit 15. Instead, the metering unit 15 is controlled such that a so-called complete delivery is carried out. This is because the high-pressure pump 16 outputs the maximum fuel amount of each
Means to send to.

In this operating mode, the amount of fuel to be injected is influenced by the pressure in the accumulator 17 being controlled and / or regulated. A pressure regulating valve 18 and a pressure sensor 19 are used for this pressure control and / or regulation.

The characteristic curve of the metering unit 15 is shown in FIG. 2a. Here, the delivery quantity F delivered from the metering unit 15 is the control current I for the metering unit 15.
Is plotted above. The metering unit 15 is in this case completely open when in a currentless state.

The high-pressure pump 16 has the maximum delivery capacity at a predetermined rotation speed. This maximum delivery capacity is obtained from the geometric delivery of the high-pressure pump 16 and the number of revolutions at each time. This maximum delivery capacity of the high-pressure pump 16 is in this case achieved only when a certain pre-delivery pressure is present upstream of the metering unit 15.

The characteristic curve of the metering unit 15 is limited to the aforementioned maximum delivery capacity of the high-pressure pump 16. This means that the metering unit 15 cannot be opened further beyond the maximum delivery capacity of the high-pressure pump 16. A metering unit 15 corresponding to a predetermined pre-delivery pressure
This characteristic curve of is designated by the reference numeral 25 in FIG. 2a.

The characteristic curve of the high-pressure pump 16 is shown in FIG. 2b. Here, the maximum delivery capacity of the high-pressure pump 16
L is plotted on the number of revolutions N ′ when the metering unit 15 is completely opened. Here, it is obvious that the rotation speed N of the internal combustion engine and the rotation speed N ′ of the high-pressure pump 16 do not have to be the same and may be multiples of each other.

As already mentioned, the premise for the maximum delivery capacity of the high-pressure pump 16 is that there is a certain pre-delivery pressure upstream of the metering unit 15. Figure 2
At b, the maximum delivery capacity of the high-pressure pump 16 in the presence of a given pre-delivery pressure for a given number of revolutions is indicated by the reference numeral 26.

However, the required pre-delivery pressure may not be present due to defects. This can occur, for example, because either filter 12 or 14 is contaminated or clogged. The pre-delivery pressure present upstream of the metering unit 15 is therefore lower than it should be.

During operation of the internal combustion engine, in particular during so-called full delivery, in other words when the metering unit 15 is operating according to the characteristic curve 25 of FIG.
The result is that the high-pressure pump 16 is no longer completely filled due to the drop in the pre-delivery pressure, so that the high-pressure pump 16 no longer delivers a quantity of fuel corresponding to the maximum delivery capacity. Finally, the high-pressure pump 16 is no longer supplied with sufficient fuel and the maximum delivery capacity is never reached.

This means the same as the shift of the characteristic curve 25 of FIG. 2a. That is, the delivery amount of the metering unit 15 decreases. In FIG. 2a, this shift is designated by reference numeral 2.
7, the characteristic curve of the metering unit 15 corresponding to the reduced pre-delivery pressure is designated by the reference numeral 28.

The insufficient filling of the high pressure pump 16 described above causes a pressure drop in the high pressure accumulator 17. This can be identified by the control device 20 via the pressure sensor 19. However, whether the pressure drop in the high pressure accumulator 17 is due to a defect in the low pressure region, that is, in the region upstream of the high pressure pump 16, or in the high pressure region, that is, in the region of the high pressure pump 16 itself. , Or whether it is due to a defect in the downstream region of the high-pressure pump, remains open.

This question can be answered by the controller 20 as follows.

When the number of revolutions of the high-pressure pump 16 is substantially constant as preset, the metering unit 15 is opened above the maximum delivery capacity of the high-pressure pump 16 belonging to this number of revolutions. That is, the metering unit 15 is opened beyond the limit. This means that the metering unit 15 can supply the high-pressure pump 16 with a larger delivery than the high-pressure pump 16 can deliver to the pressure accumulator 17 on the basis of its geometrical delivery capacity. The characteristic curve 26 of FIG. 2a for the maximum delivery capacity of the high-pressure pump 16 is thus, virtually,
It is shifted to a larger value. This is indicated by the characteristic curve 29 and the arrow 30 in FIG. 2b.

Let us now consider the case where the pressure drop in the high pressure accumulator 17 is due to a defect in the low pressure region, for example due to contamination of the filter 12 or 14, as already mentioned. In this case, if the metering unit 15 is opened further, a relatively large delivery amount can reach the high pressure pump 16 from the metering unit 15. This will ultimately compensate for the reduced pre-delivery pressure upstream of the metering unit 15. To that extent, a defective pre-delivery pressure drop is compensated. This is indicated in FIG. 2a by arrow 30 as in FIG. 2b.
The metering unit 15 thereby returns to the characteristic curve 25 again.

This is because the maximum delivery amount of the high pressure pump 16 is
The result is that it is again delivered in practice, so that the pressure in the accumulator 17 rises again to a value corresponding to a defect-free drive. This increase in pressure is identified by the control device 20 via the pressure sensor 19. Based on this pressure increase, the control device 20 can estimate a defect in the low pressure region.

Next, let us consider a case where the pressure drop in the high pressure accumulator 17 is due to a defect in the high pressure region. In this case as well, a further opening of the metering unit 15 results in that a relatively large delivery can be reached from the metering unit 15 to the high-pressure pump 16. However, due to a defect in the high-pressure region, this does not lead to an increase in pressure in the pressure accumulator 17, for example if the injection valve 21 is not completely closed. Instead, this pressure remains at a defective, reduced value. As a result, the pressure in the pressure accumulator 17 is still reduced, so that the control device 20 can estimate the defect in the high pressure region.

[Brief description of drawings]

1 is a block circuit diagram of an embodiment of an internal combustion engine of the present invention for a motor vehicle.

FIG. 2 is a diagram showing operating parameters of the internal combustion engine of FIG.

[Explanation of symbols] 10 Fuel supply system 11 Fuel tank 12 First filter 13 Pre-delivery pump 14 Second filter 15 Metering unit 16 High pressure pump 17 Accumulator / high pressure accumulator / fuel accumulator 18 Pressure regulating valve 19 Pressure sensor 20 Control device 21 injection valve N Internal combustion engine speed T Engine temperature of internal combustion engine

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 65/00 307 F02M 65/00 307 (72) Inventor Ramona Remy Federal Republic of Germany Auenwald-Hoenweiler im Gelsten felt 8 F term (reference) 3G066 AB02 AC09 AD04 BA29 BA30 BA31 BA35 BA69 CE13 DA06 DC18 3G084 BA11 DA27 DA28 EB12 EB22

Claims (8)

[Claims] 1. A method of driving an internal combustion engine of an automobile, wherein fuel is supplied from a metering unit (15) to a high pressure pump (16), and fuel is supplied from the high pressure pump (16) to a pressure accumulator (1).
The fuel sent to the high pressure pump (16) from the metering unit (15) is sent to the high pressure pump (1).
In the type of 6) which is restricted according to the maximum delivery capacity, when the pressure in the pressure accumulator (17) drops, fuel is supplied from the metering unit beyond the limit, and then the pressure accumulator (17). A driving method, characterized in that if the internal pressure rises, it is estimated that a defect exists in the upstream region from the high-pressure pump (16). 2. The method according to claim 1, wherein if no pressure rise occurs in the pressure accumulator (17), it is presumed that there is a defect in the region of the high-pressure pump (16) or in the downstream region of the high-pressure pump (16). . 3. The method as claimed in claim 1, wherein the fuel supply from the metering unit (15) which exceeds the limit is carried out when the rotational speed is substantially constant as set. 4. The maximum delivery capacity of the high pressure pump (16) is
Achieved on the premise that the pre-delivery pressure upstream of the metering unit (15) is predetermined.
4. The method according to any one of 1 to 3. 5. A control unit (20) for an internal combustion engine of a motor vehicle having a program code, which when run on a computer, is suitable for carrying out the method according to claim 1. Computer program for. 6. Computer program according to claim 5, wherein the program code is stored on a computer-readable data carrier. 7. A control device for an internal combustion engine of a motor vehicle (2)
0), in the internal combustion engine fuel is supplied from the metering unit (15) to the high-pressure pump (16) and delivered from the high-pressure pump (16) to the pressure accumulator (17), the metering unit (15) In the type in which the fuel supplied from the high pressure pump (16) to the high pressure pump (16) is limited according to the maximum delivery capacity of the high pressure pump (16), if the pressure in the pressure accumulator (17) decreases, the control device (2
0) exceeds the limit by the fuel metering unit (15)
If the pressure in the accumulator (17) rises subsequently,
A control device, characterized in that it is estimated that a defect exists in an upstream region from the high-pressure pump (16). 8. An internal combustion engine for an automobile, in which fuel is supplied from a metering unit (15) to a high pressure pump (16) and from the high pressure pump (16) into a pressure accumulator (17). The fuel sent out and supplied from the metering unit (15) to the high pressure pump (16) receives the high pressure pump (1
In the type which is restricted according to the maximum delivery capacity of 6), when the pressure in the pressure accumulator (17) decreases, the control device (2
0) exceeds the limit by the fuel metering unit (15)
If the pressure in the accumulator (17) rises subsequently,
An internal combustion engine, characterized in that it is presumed that a defect exists in the upstream region from the high pressure pump (16).