JP2003531999A - Method of operating a fuel supply system for an internal combustion engine, for example a vehicle internal combustion engine - Google Patents

Abstract

(57) Summary The present invention relates to a fuel supply system (1) for an internal combustion engine, for example, a vehicle internal combustion engine. According to this fuel supply system (1), fuel is pumped to the accumulator (2) by the pumps (6, 10). Then, the pressure in the accumulator (2) is measured, and the pressure in the accumulator (2) can be changed by controlling the pressure control valve (4). In this case, the pressure control valve (4) can be fully opened by the control device (16), and the pressure measured in the accumulator (2) can be compared with the expected pressure by the control device (16). it can.

Description

Detailed Description of the Invention

The present invention relates to a method for operating a fuel supply system for an internal combustion engine, for example a vehicle internal combustion engine. In this method, the fuel is pumped to the pressure accumulator by the pump, the pressure in the pressure accumulator is measured, and the pressure in the pressure accumulator is variable by the control of the pressure control valve.
The invention further relates to a fuel supply system for an internal combustion engine corresponding to this method and a control device for such a fuel supply system.

With regard to internal combustion engines, such as automobile internal combustion engines, there is an ever increasing demand for reducing fuel consumption and produced exhaust gas, and at the same time, it is desired to increase the output. To this end, modern internal combustion engines are provided with a fuel supply system in which the fuel supply to the combustion chambers of the internal combustion engine is electronically controlled and / or regulated, for example by a computer-aided controller. As a result, fuel can be directly injected into the intake pipe of the internal combustion engine or into the combustion chamber of the internal combustion engine.

In the case of the last-named type, so-called direct injection, it is necessary, in particular, to apply a pressure to inject the fuel into the combustion chamber. An accumulator is provided for this purpose, in which the fuel is pumped by a pump and placed in a high-pressure state. Then, fuel is injected from the pressure accumulator into the combustion chamber of the internal combustion engine via the injection valve.

However, because of the high pressure, it is possible that parts of the fuel supply system may change, for example due to aging. Therefore, there is a possibility that the performance of the pressure control valve capable of controlling and / or adjusting the pressure in the pressure accumulator will gradually change.
Furthermore, the pressure control valve may suddenly fail due to dirt. As a result of this change in the function of the pressure control valve, misfire may be caused or other malfunction of the internal combustion engine may occur.

OBJECTS AND ADVANTAGES OF THE INVENTION An object of the present invention is to enable a malfunction of a pressure control valve that gradually occurs to be detected quickly and reliably in a method of operating a fuel supply system for an internal combustion engine.

According to the invention, this problem is solved in a method or fuel supply system of the type mentioned at the outset by opening the pressure control valve fully and comparing the measured pressure in the accumulator with the expected pressure. To be done.

As a result of the pressure control valve being fully opened, dynamic pressure is generated at the pressure control valve.
This dynamic pressure can be obtained in advance in a normal pressure control valve. In this case, the dynamic pressure depends in particular on the parameters of the pressure control valve, for example on the cross-flow cross-section of the pressure control surface. By measuring the actual pressure in the pressure accumulator after the pressure control valve is completely opened, the dynamic pressure currently occurring at the pressure accumulator control valve is finally measured. This measured dynamic pressure is compared with the expected dynamic pressure, and from this comparison the functional normality of the pressure control valve can be deduced.

The method according to the invention can be carried out quickly and without great effort. Further, according to this method, it is possible to identify with high reliability whether or not the pressure control valve is normal. In this case, the method according to the invention can be carried out during operation of the internal combustion engine, but it can also be carried out during inspection of the internal combustion engine, for example in a factory.

It is extremely advantageous to measure the pressure in the pressure accumulator after a waiting time after opening the pressure control valve. This ensures that the dynamic pressure is completely built up at the pressure control valve.

According to an advantageous embodiment of the invention, the expected pressure is determined as a function of normal pressure control valve parameters and / or as a function of the current internal combustion engine operating quantity.

If the measured pressure is greater than the expected pressure, the pressure control valve is identified as dirty.

According to one advantageous embodiment of the invention, the internal combustion engine is in the engine braking or idling state. These are the operating conditions of the internal combustion engine in which the method according to the invention can be carried out very well.

It is likewise advantageous that the temperature and / or the speed of the internal combustion engine are within the permissible range. This further improves the reliability of the method according to the invention.

Other features, applications and advantages of the invention can be read from the description of the exemplary embodiments of the invention depicted in the drawings and described below. It should be noted that all the features described below or shown in the drawings form the subject of the present invention by themselves or in any combination, and this is to be construed in the scope of claims and the subordination of the claims. It does not depend on the relationship, nor does it depend on their representation or drawing in the following description and drawings.

[0015]   Examples of the present invention   FIG. 1 is a diagram showing one embodiment of a fuel supply system according to the present invention.

FIG. 2 is a flow chart showing an embodiment of a method of operating the fuel supply system according to the present invention shown in FIG.

A fuel supply system 1 is depicted in FIG. 1, which system is provided for application in a motor vehicle internal combustion engine. The fuel supply system 1 is a so-called common rail system, which is used especially in direct injection internal combustion engines. Common rail fuel supply systems of this kind are known for both gasoline and diesel internal combustion engines.

The fuel supply system 1 has a pressure accumulator 2, which is provided with a pressure sensor 3 and a pressure control valve 4. The pressure accumulator 2 is connected to a high pressure pump 6 via a pressure line 5. Furthermore, the high-pressure pump 6 is connected to a pressure control valve via a pressure line 8. The pressure control valve 4 and thus also the high-pressure pump 6 are preferably connected to an electrically operated fuel pump 10 via a pressure line 9 and a filter, which fuel pump is suitable for sucking fuel from a fuel tank 11. It is a thing.

The fuel supply system 1 has four injection valves 13, which are connected to the pressure accumulator 2 via pressure lines 14. The injection valve 13 is suitable for injecting fuel into a corresponding internal combustion engine combustion chamber.

The pressure sensor 3 is connected to a control device 16 by a signal line 15, to which a plurality of further signal lines are connected as input lines. The fuel pump 10 is connected to the control device 16 via the signal line 17, and the pressure control valve 4 is connected to the control device 16 via the signal line 18. Furthermore, the injection valve 13 is connected to the control device 16 via a signal line 19.

Fuel is pumped by the fuel pump 10 from the fuel tank 11 to the high pressure pump 6. The use of the high-pressure pump 6 creates a pressure in the pressure accumulator 2 which is measured by the pressure sensor 3 and can be adjusted to the desired value by operating the pressure control valve 4 accordingly. . Then, the fuel is injected into the combustion chamber of the internal combustion engine through the injection valve 13.

The pressure in the accumulator 2 is of particular importance for the determination of the injected fuel quantity or fuel mass. The higher the pressure in the accumulator 2, the more fuel is injected into the combustion chamber during the same injection time. This pressure in the accumulator 2 can be set and adjusted by the control device 16.

When the control device 16 controls the pressure control valve 4 to be closed for this purpose, the pressure in the pressure accumulator 2 is further increased by the high pressure pump 6 and the fuel pump 10. On the contrary, when the control device 16 controls the pressure control valve 4 to open, the fuel is discharged from the pressure accumulator 2 again, and the pressure in the pressure accumulator 2 is reduced again.

Dynamic pressure is generated at the pressure control valve 4 in the fully opened state. This dynamic pressure depends on the open cross-sectional area of the pressure control valve 4 and the amount of fuel flowing through. On the other hand, the latter fuel amount depends, inter alia, on the internal combustion engine speed, the discharged fuel amount and the injected fuel amount to the internal combustion engine. As the operating time of the pressure control valve 4 becomes longer, the through flow cross-sectional area of the pressure control valve 4 may become gradually smaller due to dirt or other deposits. As a result, the pressure accumulator 2 acted upon by the pressure control valve 4.
The internal pressure gradually changes. In particular, if the cross-sectional flow area of the pressure control valve 4 is small, a pressure in the pressure accumulator 2 will be higher than the pressure that should be applicable in the first place. In an extreme case, the through-flow cross section of the pressure control valve 4 is completely blocked and its function cannot be fulfilled, that is, the fuel supply system 1 fails.

According to the method shown in FIG. 2, the manner in which the pressure control valve 4 gradually becomes dirty is identified. The method according to FIG. 2 is carried out by the control unit 16.

At block 21, the control unit 16 checks whether the internal combustion engine temperature is within an allowable range. This is necessary for the method according to FIG. 2 to be implemented reliably. If the temperature is not within the acceptable range, the method according to FIG. 2 is stopped and restarted at a later point.

If the internal combustion engine temperature is within the permissible range, the following block 22 checks whether the internal combustion engine is in the fuel cutoff state during engine braking. In this state the internal combustion engine is driven "externally". An example can be given when the vehicle is traveling downhill, in which case the driver is not operating the accelerator pedal or the clutch pedal, so the transmission is connected but has no driving force. Then the car will roll down the slope. In this state, the internal combustion engine is "propulsed" by the car rolling downhill. Therefore, this state is also referred to as propulsion operation (or engine braking operation).

If the internal combustion engine is not in such an engine braking condition, the method according to FIG. 2 is discontinued and repeated at a later point in time. However, if the internal combustion engine is in the engine brake operating state, in block 23, the pressure control valve 4 (DSV) causes the controller 1
Completely opened by 6.

At block 24, the controller 16 waits for the waiting time to elapse until dynamic pressure is created in the pressure control valve 4. This waiting time depends on the pressure control valve 4 and can be determined beforehand and stored in the control unit 16.

After the waiting time has elapsed, the pressure in the pressure accumulator 2 is measured by the pressure sensor 3 in block 25. This measurement is instructed and executed by the control device 16. Since the pressure control valve 4 is fully open, the pressure measured here is the dynamic pressure in the pressure control valve 4.

In the following block 26, the controller 16 calculates a comparison value for the dynamic pressure. This comparison value is the expected pressure that would naturally occur if the pressure control valve 4 were normal. This comparison value depends on the current operating state of the internal combustion engine, that is, the current operating amount of the internal combustion engine, such as the rotational speed of the internal combustion engine and the engine temperature. Furthermore, the comparison value depends on the parameter of the pressure control valve 4, which is the control device 1
6 is stored in the characteristic curve or the characteristic map. The above-mentioned parameters relate to the normal pressure control valve 4, and can be obtained in advance from a new pressure control valve 4 and stored in the control device 16, for example.

In the following block 27, the control unit 16 again checks whether the internal combustion engine is still in the fuel cutoff state during engine braking. If this is no longer the case, the method according to FIG. 2 is discontinued and later repeated.

If the internal combustion engine is still in propulsion operation, at block 28 the controller 16
Thus, the measured dynamic pressure is compared with the comparison value (maximum value). If the measured dynamic pressure is less than the comparison value, then in block 29 the controller 16 estimates that the pressure control valve 4 is normal.

On the other hand, if the measured dynamic pressure is greater than the calculated comparison value, block 3
At 0, the controller 16 estimates that the throughflow cross section of the pressure control valve 4 is dirty.

In the method described above, the idling operation of the internal combustion engine may be selected instead of the engine braking operation. In addition to the precondition that the internal combustion engine temperature must be within the permissible range, another precondition for performing the method shown in FIG. 2 is that the internal combustion engine rotational speed must be within the permissible range. It may be configured as follows.

The method described can be implemented during operation of the internal combustion engine. It is also possible to carry out the method in factories with corresponding test equipment.

The already-mentioned parameters of the normal pressure control valve 4 can generally be determined and stored for a given internal combustion engine type, but may be determined and stored individually for each internal combustion period. Further, when the pressure control valve 4 is replaced, new parameters can be obtained and read by the control device 16.

[Brief description of drawings]

[Figure 1]   1 is a diagram showing one embodiment of a fuel supply system according to the present invention.

2 is a flow chart illustrating one embodiment of an operating method of the fuel supply system according to the present invention shown in FIG.

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] April 5, 2002 (2002.4.5)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Harald Lang             Germany Mark Groningen               Porsche Strasse 9 (72) Inventor Hans Jörg Bochum             United States Michigan Novi Par             Mer Drive 30842 F term (reference) 3G084 BA14 CA03 CA06 DA27 EA05                       EA07 EA11 EB06 EB22 EC01                       FA00 FA20 FA33                 3G301 JB09 KA07 KA16 LB06 NB03                       NE23 PB08B PE01B PE08B

Claims (10)

[Claims] 1. Fuel is pumped by a pump (6, 10) to a pressure accumulator (2), a pressure in the pressure accumulator (2) is measured, and a pressure in the pressure accumulator (2) is a pressure. In a method of operating a fuel supply system for an internal combustion engine, for example a vehicle internal combustion engine, of the type which is variable by the control of a control valve (4), the pressure control valve (4) is fully opened and measured in the pressure accumulator (2). A method of operating a fuel supply system, characterized in that the pressure is compared to the expected pressure. 2. The method according to claim 1, wherein the pressure in the pressure accumulator (2) is measured only after a waiting time after the pressure control valve (4) is opened. 3. The method according to claim 1, wherein the expected pressure is determined as a function of the parameters of a normal pressure control valve (4). 4. An expected pressure is determined depending on the current internal combustion engine operating amount,
The method according to any one of claims 1 to 3. 5. The method according to claim 1, wherein the pressure control valve is identified as dirty if the measured pressure is greater than the expected pressure. 6. The method according to claim 1, wherein the internal combustion engine is in an engine braking operating state or an idling operating state. 7. The temperature and / or the rotational speed of the internal combustion engine are within an allowable range,
7. A method according to any one of claims 1 to 6. 8. An electrical control element for a control device (16) of an internal combustion engine, for example a vehicle internal combustion engine, in a flash memory or a read-only memory, implemented in a computing device, for example a microprocessor.
An electric control element, characterized in that a program suitable for carrying out the method according to the section is stored. 9. Fuel pump (6, 10) in a fuel supply system (1)
Is pumped to the accumulator (2) by the pressure in the accumulator (2).
Of the fuel supply system (1) for an internal combustion engine, for example a vehicle internal combustion engine, in which the pressure in the accumulator (2) is variable by the control of a pressure control valve (4) (
In 16), the pressure control valve (4) is fully opened by the controller (16) and the pressure measured in the accumulator (2) by the controller (16) is compared with the expected pressure. Characteristic, control device of fuel supply system. 10. Fuel is pumped to a pressure accumulator (2) by a pump (6, 10), a pressure in the pressure accumulator (2) is measured, and a pressure in the pressure accumulator (2) is a pressure. In a fuel supply system (1) for an internal combustion engine, for example a vehicle internal combustion engine, of the type which is variable under the control of a control valve (4) and which is provided with a control device (16), When the control valve (4) is fully opened, the control device (16
2.) A fuel supply system, characterized in that the pressure measured in the accumulator (2) is compared with the expected pressure by).