JPH1068328A - Injection system monitoring method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost and simple monitoring of a pressure limiting valve in a method and an apparatus for monitoring an injection system. The above object is achieved by providing at least one pump for supplying fuel from a low pressure region to a high pressure region and providing a pressure limiting valve, and the pressure limiting valve switches the high pressure region when the pressure in the high pressure region exceeds a threshold value. Connect to low pressure area,
Under predetermined operating conditions, the means for controlling the pressure is controlled such that the pressure limiting valve connects the high pressure region to the low pressure region without error and the pressure in the high pressure region is evaluated for error identification. It is solved by.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and a device for monitoring an injection system, for example for an internal combustion engine having a common rail system.

[0002]

2. Description of the Related Art A method for monitoring an internal combustion engine is known, for example, from Japanese Patent Publication No. 63143383. It describes the so-called common rail system,
In this common rail system, a pump (not shown) supplies fuel from a low pressure region to a high pressure region. The pressure of the high-pressure area rail can be adjusted to a predetermined value by the pressure adjusting valve. The valve opens the connection between the high pressure region and the low pressure region when the pressure in the high pressure region reaches a predetermined value. This valve is used to control the pressure in the high pressure area.

If the pressure exceeds a predetermined threshold, this is indicated by a signal lamp. Other measures are not performed automatically and need to be performed by the driver.

Another fuel injection system for diesel engines is disclosed in MTZ Motortechnische Zeitung 54,1993,11.
Pages 588 to 599. In this system, the pressure is regulated by the control of a high-pressure pump, depending on a comparison between a desired value and an actual value of the pressure. If the pressure exceeds a predetermined value, a pressure limiting valve opens the connection between the high pressure area and the fuel tank. The monitoring of this pressure limiting valve is not described.

Further, German Patent Application Publication No. 38027
From U.S. Pat. No. 71, a safety system for an internal combustion engine is known. In this safety system, the amount of fuel supplied to the internal combustion engine for monitoring the safety switching valve in the overrun operating state (engine braking operating state) is generated by the injection in which the response signal is actually performed. Up to If an injection is identified, the safety switching valve is controlled and it is checked after the injection whether an injection is still taking place.

[0006] Common rail systems often use pressure limiting valves in addition to pressure regulating valves. The pressure limiting valve opens the connection between the high pressure region and the low pressure region when the pressure exceeds the maximum allowable value. This safety valve is always closed during normal operation. This valve is only opened in the event of a fault which results in a very high pressure rise.

[0007] Sticking (heavy movement), fouling, freezing, or external damage can prevent this pressure limiting valve from functioning.
In the unlikely event that a corresponding fault is not identified, this will cause a pressure limit valve failure and unacceptable system pressure. This can also lead to overloading of the individual components of the system, which can lead to destruction of the injection system or the internal combustion engine or leakage of fuel into the combustion chamber.

[0008] Failure of the pressure limiting valve cannot be easily identified. This is because the pressure limiting valve usually only works if the system is faulty, for example if the pressure exceeds a threshold. In normal operation, this pressure limiting valve usually does not work.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive and simple monitoring of a pressure limiting valve in an injection system monitoring method and apparatus.

[0010]

The above object is achieved by at least one pump supplying fuel from a low pressure region to a high pressure region,
A pressure limiting valve for connecting the high pressure region to the low pressure region when the pressure exceeds a threshold value in the high pressure region, and further controlling a means for controlling the pressure in a predetermined operating state; This is solved by connecting the high-pressure region to the low-pressure region in an error-free manner with the pressure-limiting valve and evaluating the pressure in the high-pressure region for error identification.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The method described here allows simple and reliable monitoring of a pressure limiting valve.

Advantageous and advantageous embodiments of the invention are set out in the dependent claims.

The invention will now be described with reference to the exemplary embodiment shown in the drawings.

FIG. 1 shows the basic components of a fuel supply system for an internal combustion engine having high-pressure injection. This illustrated system is commonly referred to as a common rail system.

At 100, a fuel tank is shown. The fuel tank includes a first filter 105,
It is connected to the second filter means 115 via the discharge pump 110. From this second filter means 115 the fuel reaches the valve 120 via a conduit. The connecting conduit between the filter means 115 and the valve 120 is connected to the fuel tank 100 via a low pressure limiting valve 140. The valve 120 is connected to a rail 130 via a high-pressure pump 125. This rail is connected to different injectors 131 via a fuel conduit. The rail 130 is connected to the fuel tank 100 via a pressure regulating valve 135. This pressure regulating valve 1
35 is controlled by a coil 136.

The conduit between the output of high pressure pump 125 and the input of pressure regulating valve 135 is called the high pressure region.
In this region, the fuel is under high pressure. The pressure in this high pressure region is detected by the sensor 150.

In addition to the pressure regulating valve 135, a pressure limiting valve 145 is provided. This pressure limiting valve 1
45 is configured as follows. That is, the connection between the high-pressure area and the low-pressure area is opened only at a predetermined pressure, so that a rapid pressure reduction is possible on the rail 130. This pressure limiting valve 14
The pressure at which 5 is opened is selected in this case as follows. That is, the value of this pressure is chosen so that it does not normally appear in normal error-free operation.

The control device 10 includes a high-pressure pump 125 and / or
Alternatively, a control signal is supplied to the pressure adjusting valve 136.

This device operates as follows. Fuel in the fuel tank is supplied by a discharge pump 110 through filter means 105 and 115. The output side of the discharge pump 110 is supplied with fuel having a pressure between 1 and approximately 3 bar. When the pressure in the low pressure region of the fuel system reaches a predetermined pressure, the valve 120 opens and a predetermined pressure is applied to the input side of the high pressure pump 125. This pressure depends on the configuration of the valve 120. Typically, this valve 120 is configured to open a connection to the high pressure pump 125 at a pressure of approximately 1 bar.

If the pressure in the low pressure region rises to an unacceptably high value, the low pressure limiting valve 140 opens, opening the connection between the output of the discharge pump 110 and the fuel tank 100. Valve 120 and low pressure limiting valve 14
By means of zero, the pressure in the low pressure region is kept at a value between approximately 1 bar and 3 bar.

The high-pressure pump 125 supplies fuel from a low-pressure area to a high-pressure area. This high pressure pump 125 creates a very high pressure on the rail 130. Usually, in the case of a system for an external ignition internal combustion engine, approximately 30 to 100
A pressure value of bar is obtained, and in the case of a self-igniting internal combustion engine a pressure value of approximately 1000 to 2000 bar is obtained. High-pressure fuel is distributed to the individual cylinders of the internal combustion engine via injectors 131.

The pressure in the rail or in the entire high pressure region is detected by the sensor 150. The pressure in the high pressure region is adjusted by a pressure adjusting valve 135 that can be controlled by the coil 136. Depending on the voltage applied to the coil 136 or the current flowing through the coil 136, the pressure regulating valve 135 is opened at various pressure values.

The pressure limiting valve 145 is activated only when the system is faulty, for example, when the pressure exceeds a predetermined threshold. During normal operation, this pressure limiting valve 1
45 does not work.

[0024] Sticking (heavy movement), fouling, freezing or external damage can prevent this pressure limiting valve 145 from functioning. In the unlikely event that no corresponding fault is identified, this will cause the pressure limiting valve 145 to fail and unacceptable system pressure. This can cause yet another serious damage to the system, for example the internal combustion engine.

In order to guarantee the function of the pressure limiting valve 145 in the unlikely event that the pressure limiting valve 145 functions, the following configuration is provided.

In a driving situation where there is no problem, the control device 1
0 is the pressure regulating valve 136 and / or the high pressure pump 12
The control of 5 raises the pressure in rail 130 to a value to which the operable pressure limiting valve 145 responds. Such a running situation occurs, for example, when fuel is not injected. This is the case, for example, with overrun operating conditions. In addition, a check is performed during the so-called run-on shutdown switching process and / or before starting. As soon as the control determines that the internal combustion engine is to be switched off, the pressure is increased until the pressure limiting valve responds.

If the pressure drops, the controller identifies a functioning pressure limiting valve 145. If the pressure exceeds a critical value, the controller identifies a malfunction of the pressure limiting valve 145 and transitions to emergency driving mode. This emergency driving mode prevents overloading of the system.

The corresponding method according to the invention is illustrated in the form of an embodiment in FIG. In step 200, an overrun operating condition is identified. This means that error monitoring is activated. This error monitoring is activated in step 200 when predetermined operating conditions are met. Such operating conditions are met, for example, when no fuel is injected. This is the case, for example, with overrun operating conditions.

Next, at step 210, the time counter t is set to zero. In the next step 220, the current pressure PA in the high pressure region is detected. Next step 2
At 30, a control signal is sent to increase the pressure. This is realized by a signal being supplied to the pressure regulating valve 135 and the pressure increasing. Additionally or alternatively,
In a correspondingly configured high-pressure pump 120, it is possible to control this so that the pressure increases.

Next, at step 240, the time counter t is incremented. In a query step 250, it is checked whether the time counter t is greater than the threshold value ts. If the time counter t is not greater than the threshold value ts, steps 220, 230 and 240 are performed again.

In the inquiry step 250, the time counter t
Is greater than the threshold ts, step 260
Is performed, and a new pressure value PN is detected. This threshold ts is selected as follows. That is, when the pressure rises to this value, the pressure limiting valve 145 is normally selected to open for error-free operation.
This means that the pressure drops after the elapse of the waiting time ts.

Therefore, in step 270, the new value PN
The pressure difference between the pressure and the value before the pressure increase PA is calculated. In step 280, it is checked whether the pressure difference PD is smaller than zero. If this pressure difference PD is smaller than 0, this means that the pressure has dropped. In this case, the program ends at step 295.

If the interrogation step 280 identifies that the pressure difference is greater than zero, this means that the pressure has not dropped, which further infers that the pressure limiting valve 145 is not open. In this case, the error is identified in step 290 and action is taken for the corresponding error. The program then similarly ends at step 295.

Optionally, at step 280, the pressure PN
However, it can also be configured to check whether the pressure limit valve is normally higher than the opening pressure PS. If the pressure PN is greater than this pressure PS, an error is identified as well.

It is advantageous to have information on the pressure limiting valve, which is always a key component in safety technology. Overload and malfunction of the injection system or of the internal combustion engine is reliably prevented. The reliability of the function of the pressure limiting valve can be guaranteed over its lifetime.

[Brief description of the drawings]

FIG. 1 is a block diagram of the device of the present invention.

FIG. 2 is a flowchart of the method of the present invention.

[Explanation of symbols]

 10 Control device 100 Fuel tank 105 First filter 110 Discharge pump 115 Second filter 120 Valve 125 High pressure pump 130 Rail 131 Injector 135 Pressure regulating valve 136 Coil 140 Low pressure limiting valve 145 Pressure limiting valve 150 Sensor

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication G01M 15/00 G01M 15/00 Z // F02M 47/02 F02M 47/02 (72) Inventor Helmut Klaus Germany Republic Eberdingen August-Laemle-Strasse 38

Claims (7)

[Claims] 1. A method of monitoring an injection system, wherein at least one pump supplies fuel from a low pressure region to a high pressure region, and a pressure limiting valve is provided, wherein the pressure limiting valve exceeds a threshold value in a high pressure region. Connecting the high pressure region to the low pressure region, and in a predetermined operating state, controlling the means for controlling the pressure so that the pressure limiting valve connects the high pressure region to the low pressure region in an error-free state; A method for monitoring an injection system, which evaluates the pressure of the system for error identification. 2. The method of claim 1, wherein an error is identified when the pressure increases. 3. The method according to claim 1, wherein an error is identified if the pressure value rises above a threshold. 4. The inspection according to claim 1, wherein the inspection is performed in an operating state in which fuel is not injected.
The method described in the section. 5. The inspection is performed in an overrun operation state (engine brake operation state).
The method according to one of the preceding claims. 6. The method according to claim 1, wherein an error of the pressure limiting valve is identified. 7. A monitoring system for an injection system, comprising: at least one pump for supplying fuel from a low-pressure region to a high-pressure region; means for controlling a pressure in a high-pressure region; The pressure limiting valve connects the high pressure region to the low pressure region when the pressure in the high pressure region exceeds a threshold, and controls the means for controlling the pressure so that the pressure restriction valve is in an error-free state. A monitoring device for an injection system, comprising means for connecting a high pressure region to a low pressure region and evaluating the pressure in the high pressure region for error identification.