KR100413304B1 - Monitoring method and monitoring device of fuel supply device - Google Patents

Abstract

And more particularly, to a monitoring method and monitoring apparatus for a common rail apparatus of a diesel engine. A fault is identified based on the output signal of the structural noise sensor.

Description

Monitoring method and monitoring device of fuel supply device

Such methods and apparatus are known from U.S. Pat. No. 5,241,933. The U.S. patent discloses a method and apparatus for monitoring a high voltage circuit in a common rail system. In the known device disclosed in the above-mentioned U.S. Patent, the pressure of the rail is controlled. If the adjustment amount of the pressure control circuit is outside the predetermined range, the apparatus identifies an error.

Also known is an apparatus for estimating the presence of an error based on the pressure of the rail. In this device, the pressure is compared with the lower limit and the upper limit, and an error is identified when the pressure is outside the predetermined value range.

The determination of such a configuration is that errors are only identified when the pressure drop is large.

The present invention relates to a monitoring method of a fuel supply apparatus according to claim 1 and an engine monitoring apparatus according to claim 8.

1 is a block circuit diagram of the present invention;

FIGS. 2A to 2C are diagrams showing the output signals of the knocking sensors plotted with time. FIG.

Figure 3 is a flow chart illustrating the steps of the method of the present invention.

4 is a schematic view of an internal combustion engine;

5 is a block circuit diagram of signal evaluation.

Figure 6 is a plot of various signals plotted against time;

An object of the present invention is to provide a monitoring device and a monitoring method for a fuel supply device of the type described above, which can reliably and simply identify an error. This problem is solved by the constitution described in the independent claim of the present invention.

With the method and apparatus of the present invention, it is possible to reliably and simply identify the error in the fuel supply device. In particular, it is possible to reliably detect the failure of the injector in the common rail system.

Advantages and advantageous configurations of the present invention are described in the dependent claims.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail based on the drawings showing embodiments.

Hereinafter, the apparatus of the present invention will be described as an example of a self-ignition type internal combustion engine. In the internal combustion engine, fuel supply is controlled by a solenoid valve. The embodiment shown in Fig. 1 corresponds to a so-called common rail system. However, the means of the present invention is not limited to this system. The present invention can be used in any system capable of providing a corresponding fuel supply.

The internal combustion engine is shown at 100. The internal combustion engine receives fresh air through a suction pipe path (105) and discharges exhaust gas through an exhaust pipe path (110).

The illustrated internal combustion engine is a four-cylinder (four-cylinder) internal combustion engine. In each cylinder of the internal combustion engine, injectors 120, 121, 122, and 123 are disposed. The injector is supplied with fuel through solenoid valves 130, 131, 132, and 133. The fuel reaches the cylinder of the internal combustion engine 100 from the rail 135 through the injectors 120, 121, 122,

The fuel of the rail 135 becomes a pressure that can be adjusted by the connected high-pressure pump 145. The high-pressure pump 145 is connected to the fuel supply pump 155 via the solenoid valve 150. The fuel supply pump is connected to the fuel storage container 160.

An electric fuel pump or a mechanical fuel pump can be used as the fuel supply pump. If an electric fuel pump is used, a forward positioning filter is required. Because of the high fuel temperature, the electric fuel pump is advantageously disposed in the vicinity of the fuel tank. This increases the volume between the electric fuel pump and the high-pressure pump, thus increasing the shut-off time. In particular, a high cost is required for rapid pressure reduction in case of failure.

The mechanical pre-feed pump disposed in the vicinity of the internal combustion engine does not have the above drawbacks. In the case of a mechanical pre-supply pump, a solenoid valve 150 is additionally required. The solenoid valve stops supplying fuel to the high-pressure pump 145 in the event of a failure. The shut-off valve 150 may alternatively be configured as a separate structural unit. However, this shut-off valve can be assembled on the suction side of the high-pressure pump 145 or on the pressurized side to the preliminary feed pump 155.

Valve 150 has a coil 152. The solenoid valves 130, 131, 132, 133 have the coils 140, 141, 142, 143. Current may be applied to the coil by an output terminal 175, respectively. The output stage 175 is advantageously arranged in the control device 170, and the control device accordingly controls the coil 152. [

In addition, a sensor 177 is provided, which detects the pressure of the rail 135 and transmits a corresponding signal to the control device 170. Reference numeral 180 denotes a so-called structure-borne noise sensor. The sensor is disposed in a place where acoustic conduction is good. The structure noise sensor supplies a signal corresponding to the control device. An acceleration sensor or a knocking sensor may be used instead of the structural noise sensor.

The apparatus operates as follows. The fuel supply pump 155 supplies fuel from the storage container to the high-pressure pump 145 through the valve 150. [ The high pressure pump 145 forms a predetermined pressure on the rail 135. Typically, the pressure in the rail 135 is greater than 800 x 0.986 hectopascals.

Current flows through the coils 140 to 143 so that the corresponding solenoid valves 130 to 133 are controlled. The control signal for the coil sets the fuel injection start and the injection end by the injectors 120 to 123, respectively. The control signal is set by the control device depending on various operating conditions, for example, the driver's turnout, the number of revolutions, and a separate parameter.

In the common rail system, the continuous injection of the injector can not be detected simply and reliably when the mass balance in the rail is balanced. This occurs, for example, when a constant current is flowing through the solenoid valve, or when the injector is locked or the airtightness is insufficient. This may result in an undesirable torque rise in the cylinder and the engine may be destroyed if the peak pressure of the cylinder or the allowable temperature is exceeded.

In the present invention, by using a structural noise sensor or an acceleration sensor, the vibration generated in the combustion chamber is detected and processed using an evaluation circuit. If the detected vibration of each cylinder deviates greatly from a normal value or an expected value, the error of the corresponding injector is estimated.

2A to 2C, the output signal of the knocking sensor is plotted with respect to the angular position of the crankshaft. FIG. 2A shows the output signal of the structure noise sensor when all the injectors operate without error, with respect to the angular position of the crankshaft. Fuel is supplied to the first cylinder at the top dead center region of the first cylinder, that is, at the crankshaft 0 °. This is an important signal for the structural noise sensor during fueling or combustion. Corresponding signals occur at 540 [deg.] In combustion at the second cylinder, 180 [deg.] At the crankshaft, 360 [deg.] At the third cylinder, and at the fourth cylinder.

Figure 2B shows the corresponding signal when there is an error in the injector of the second cylinder. The sound emission at the time of combustion of the second cylinder is clearly extended. This indicates that the injector of the second cylinder is not operating normally. The injector is in an open state longer than expected.

2C, no fuel is injected into the second cylinder. This means that the injector attached to the second cylinder can not regulate the amount of fuel.

In Fig. 3, an evaluation method for error identification is illustrated. In step 300, the output signal of the structural noise sensor is detected upon supply of the fuel quantity to the first cylinder Z1. Correspondingly, at step 301, a structural noise sensor signal at the time of combustion in the second cylinder Z2 is detected. In steps 302 and 303, a structural noise sensor signal for the cylinders Z3 and Z4 is detected. In step 310, the amplitudes of the four signals are added and divided by four. Thereby, the average value M of the four structural noise sensor signals is obtained.

The counter i is set to zero in step 320, and is incremented by one in step 330 in succession. In the query step 340, it is checked whether the difference between the amplitude of the i-th cylinder Zi and the average value M is greater than the threshold value S or not. If not, at query step 350, it is checked whether i is 4 or more. If i is not equal to or greater than 4, a new step 330 is performed and if i is 4 or greater, step 300 continues.

If it is determined at query step 340 that the absolute value of the difference between the amplitude of the i-th cylinder Zi and the mean value M is greater than the threshold value S, then an error is identified at step 360, / RTI >

The above method has been described as an example of a four-cylinder internal combustion engine. By properly selecting the parameters, in particular i, the method of the present invention can be applied to internal combustion engines of other cylinder numbers.

Optionally, the duration of the signal, rather than the amplitude of the signal, can be evaluated for error identification.

Other advantageous configurations are shown in the following figures. FIG. 4 shows a four-cylinder diesel engine having two schematic structural noise sensors 410 and 411 in outline. These structural noise sensors are attached to the engine so as to be conducted acoustically. Reference numeral 415 denotes a needle movement sensor, and reference numeral 420 denotes a cylinder pressure sensor. Reference numeral 105 denotes a fresh air duct, and reference numeral 110 denotes an exhaust gas duct.

In Fig. 5, a signal evaluation section for two knocking sensors 410 and 411 is shown as a block circuit diagram. The output signal of the first knock sensor 410 is supplied to the cylinder selection unit 220 via the delay time correction unit 201. The output signal of the second knocking sensor 411 is supplied to the cylinder selecting unit 220 via the second delay time correcting unit 202 in a corresponding manner.

A signal is supplied to the first band pass filter 210 and the second band pass filter 215 from the cylinder selector 220. The output signal of the band-pass filter is supplied to the signal processing unit 230, and the signal processing unit supplies the signal to the engine control unit 240 again. The output signals of the band-pass filters 210 and 215 are also supplied directly to the engine control device 240. The signal processing unit 230 also processes signals of various sensors 235.

These devices operate as follows. If the signals are different, the delay time from the signal source to the other knock sensors 410 and 411 is also different. The delay time is compensated by the delay time correctors 201 and 202. The cylinder selection unit assigns a signal to a predetermined sensor based on the signal level. The signal level also depends on the distance from the source to the sensor. Thus, the allocation between the detected signal and the predetermined cylinder is executed.

Basically, the steps described below can also be carried out by a structural noise sensor. Signal quality is significantly improved by using two or more structural noise sensors. It is particularly advantageous to place the structural noise sensor in a spatially different structure in the engine. By adding the delay-time-corrected signal, a useful signal can be significantly increased compared with the noise signal.

In the present invention, the first bandpass filter has a cutoff frequency of 10 kHz and 30 kHz. The second bandpass filter has cutoff frequencies of 500 Hz and 4 kHz. The frequency value is a simple guide value and can be changed according to each type of the internal combustion engine.

The bandpass filter filters the output signals of the knock sensors 410 and 411. Based on the filtered signal, the signal processing section detects various parameters characterizing the injection or combustion. The thus obtained signal is used for control and adjustment of the internal combustion engine by the engine control unit.

C) represents an output signal of the knocking sensor; d) represents an output signal of the first band-pass filter; e) represents a second band-pass filter Are respectively plotted with respect to time. When the amount for the preliminary injection is small, the valve needle generally does not open to the upper stopper.

At the time of the preliminary injection, the collision of the needle at the lower stopper is only identified at the end of the injection process. At this point, the amplitude of the output signal of the knock sensor rises. At this point, the high frequency component of the output signal of the knock sensor increases. This point is shown as VE.

At the start and end of the main injection, the needle of the needle movement sensor moves to the lower stopper or the upper stopper. At this time point, the amplitude of the output signal of the knocking sensor rises, and in particular, the high frequency component increases. This point is shown as HE.

The injection start and injection end of the main injection are identified when the needle of the injectors 120 to 123 is moved to the upper stopper when the needle is opened and when the needle is closed to the lower stopper. This point is identified based on the fact that the output signal of the first band-pass filter rises above the first threshold value. Continuous injection is identified if a collision of the needle of the injector is not identified, or if a collision at the time of closing of the injector is not identified.

Based on these signals, it is detected whether or not there is continuous injection at each injection. Monitoring is advantageously done separately for each cylinder. A fault is identified if a predetermined number of continuous injections are identified in one cylinder.

If the fuel supply pump is constructed as a mechanical preliminary feed pump, for example as a gear pump, there is no direct means to stop the supply of fuel by the preliminary feed pump. This is because the preliminary feed pump is directly driven by the engine. Therefore, according to the present invention, the supply of fuel to the high-pressure pump 145 by the preliminary feed pump 155 is stopped by the electrically shut-off valve between the preliminary feed pump 155 and the high-

If a fault is identified, valve 150 stops fueling to high pressure pump 145. Here, the failure can be identified, for example, as described above. However, other methods for identifying faults are also possible.

When the valve 150 is configured as a 2/2 valve, that is, when the flow between the preliminary feed pump 155 and the high-pressure pump 145 is blocked, a pressure is formed upstream from the valve when the valve is closed. Appropriate means must be provided to avoid pressure build up. For example, the pressure control valve can be assembled to the preliminary feed pump. Alternatively, the shut-off valve may be configured as a 3/2 valve. In this case, when the valve 150 is being controlled, the fuel is directly returned from the preliminary feed pump 155 to the fuel storage container 160 via the channel shown by the broken line. In the case of such a configuration, the pressure control valve of the preliminary feed pump 155 may be omitted.

Claims (9)

1. A method for monitoring a fuel supply system in an engine including a plurality of cylinders in which fuel is supplied from a low pressure region to a high pressure region by one or more pumps, Generating an output signal from the structural noise sensor for each of the plurality of cylinders, Calculating an average value of the output signals from the plurality of cylinders, and And identifying a failure of the fuel supply device when the output signal of the specific cylinder deviates from the average value by a predetermined value or more. 1. A method for monitoring a fuel supply system in an engine including a plurality of cylinders in which fuel is supplied from a low pressure region to a high pressure region by one or more pumps, Generating an output signal having a duration from the structural noise sensor for each of the plurality of cylinders, Calculating an average duration of an output signal from the plurality of cylinders, and And identifying a failure of the fuel supply system if the duration of the output signal of the specific cylinder deviates from the average duration by a predetermined value or more. 2. The method of claim 1, wherein each of the plurality of cylinders has an injection period, Filtering the output signal to produce a filtered signal, Determining the start and end of the injection period as a function of the filtered signal, respectively, and Generating a signal representative of the start and end of the injection period, Wherein a failure of one of the plurality of cylinders is identified as a function of a signal indicative of the beginning and end of the injection period, respectively. 4. The method according to claim 3, wherein the failure is identified when a delay between a signal indicative of the start of the injection period and a signal indicative of the end of the injection period obtains a predetermined delay value. The method according to claim 1, wherein the identified fault includes a defect in the solenoid valve. The method according to claim 1, wherein the identified fault includes a defect in the fuel injector. A method for monitoring a common rail fuel supply device in a diesel fuel engine, wherein fuel is supplied from a low pressure area to a high pressure area by one or more spare fuel pumps, Identifying an operational failure of the fuel supply device, and And interrupting the fuel flow between the preliminary fuel pump and the high-pressure pump when the failure is identified. 1. A fuel supply apparatus comprising at least one pump having a high-pressure pump and at least one preliminary supply pump, the fuel supply apparatus comprising: a fuel supply device in which fuel is supplied from a low-pressure region to a high-pressure region by the preliminary supply pump; A sensor having a structural noise sensor or an acceleration sensor for generating an output signal and attached to the engine, An evaluation circuit coupled to the sensor, the evaluation circuit identifying a failure of the fuel supply device if the output signal deviates from a predetermined value; An engine monitoring device coupled to the fuel supply device and including means for preventing fuel flow from the preliminary feed pump to the high pressure pump, 9. The engine monitoring apparatus according to claim 8, wherein the engine includes a diesel fuel engine and the fuel supply apparatus includes a common rail fuel supply apparatus.

Images