CN110985224B - Method and system for judging working state of oil sprayer at initial starting stage of diesel engine - Google Patents

Abstract

The invention discloses a method and a system for judging the working state of a fuel injector at the initial stage of starting a diesel engine, and relates to the field of engines. The method includes the following steps: obtaining the running state of the engine; judging whether the running state of the engine is the starting stage; if so, obtaining each cylinder the actual rail pressure at the initial stage of injection and the lowest rail pressure during the injection process; use the formula to obtain the real-time injection rail pressure deviation of each cylinder; judge whether the real-time injection rail pressure deviation of each cylinder is less than or equal to the preset rail pressure deviation threshold; if so, If an error is reported once, the counter used to accumulate the number of errors reported by each cylinder is accumulated; it is judged whether the accumulated number of times is greater than or equal to the preset number of times threshold; if so, a fault signal is output for the injector of the corresponding cylinder, and the corresponding counter is cleared. Therefore, the present invention can judge the working state of the fuel injector at the initial stage of engine starting, and effectively lock whether the failure to start the diesel engine is related to the fuel injector.

Description

A method and system for judging the working state of a fuel injector in the initial stage of a diesel engine

technical field

The invention relates to the technical field of engines, in particular to a method and a system for judging the working state of a fuel injector at the initial stage of starting a diesel engine.

Background technique

In the initial stage of diesel engine starting, especially in the early stage of cold start, the fuel injector may not be able to inject fuel normally due to low battery voltage, stuck injector or consistency of the injector, and in severe cases, it may even fail to start.

At present, the control logic of the diesel engine ECU cannot be recognized, and the start fails due to the abnormal working state of the injector. As shown in Figure 4, in the initial stage of diesel engine startup, when a cylinder starts to ignite, the diesel in the high-pressure common rail pipe 1 will be injected into the combustion chamber through the injector 3 immediately. The opening of the unit valve and the engine speed remain basically unchanged, so the oil intake remains unchanged, so the diesel pressure in the high-pressure common rail pipe 1 will decrease rapidly. In fact, the volume of the high-pressure common rail pipe 1 should theoretically reduce the oil supply pressure fluctuation of the high-pressure oil pump and the pressure fluctuation caused by the injection process of each injector. When it is low, the accumulating effect is not obvious.

Usually, the rail pressure changes during the normal injection at the beginning of the start. When the 1st cylinder is fired, the rail pressure drops by 58bar, the 3rd cylinder is 70bar, the 4th cylinder is 72bar, and the 2nd cylinder is 61bar.

SUMMARY OF THE INVENTION

In view of the above deficiencies, the technical problem to be solved by the present invention is to provide a method and system for judging the working state of the fuel injector in the initial stage of starting the diesel engine, which can judge the working state of the fuel injector at the initial stage of engine starting, and effectively lock the starting of the diesel engine. Is the failure related to the injector.

For solving the above-mentioned technical problems, the technical scheme of the present invention is:

A method for judging the working state of a fuel injector in the initial stage of starting a diesel engine, comprising the following steps:

Get the engine running status;

Determine whether the engine running state is the starting stage;

If yes, obtain the actual rail pressure at the initial stage of injection and the lowest rail pressure during the injection process of each cylinder;

Use the formula to obtain the real-time injection rail pressure deviation of each cylinder, the formula is: real-time injection rail pressure deviation = actual rail pressure at the initial stage of injection - minimum rail pressure during injection;

Determine whether the real-time injection rail pressure deviation of each cylinder is less than or equal to the preset rail pressure deviation threshold;

If it is, it will report an error once, and the counter used to accumulate the number of errors reported by each cylinder is accumulated;

Determine whether the accumulated number of times is greater than or equal to the preset number of times threshold;

If it is, output the failure signal of the injector of the corresponding cylinder, and clear the corresponding counter.

Preferably, before the step of judging whether the real-time injection rail pressure difference of each cylinder is less than or equal to a preset rail pressure deviation threshold, the following steps are further included:

Get engine speed and fuel injection quantity;

Find the pre-calibrated map table according to the engine speed and fuel injection quantity, and find the calibration rail pressure deviation;

The calibrated rail pressure deviation is used as the rail pressure deviation threshold.

Preferably, after the step of calibrating the rail pressure deviation is found, the following steps are further included:

According to the actual rail pressure at the initial stage of injection of each cylinder, find the pre-calibrated correction curve, and find the correction coefficient;

Then the rail pressure deviation threshold is the product of the calibration rail pressure deviation and the correction coefficient.

A system for judging the working state of an injector in the initial stage of starting a diesel engine, comprising an electronic control unit, and further comprising: a state detection unit electrically connected to the electronic control unit respectively, and the state detection unit is used for judging whether the engine runs to the start stage ; Rail pressure detection unit, the rail pressure detection unit is used to obtain the actual rail pressure at the initial stage of injection and the lowest rail pressure during the injection process of each cylinder, and obtain the Real-time injection rail pressure deviation; a fault diagnosis unit, the fault diagnosis detection unit compares the real-time injection rail pressure deviation of each cylinder with a preset rail pressure deviation threshold, and when the real-time injection rail pressure deviation is less than or equal to the preset rail pressure deviation When the threshold is set, the corresponding cylinder error signal is issued once; a counting unit, the counting unit is used to accumulate the number of errors reported by each cylinder; the electronic control unit judges whether the number of errors accumulated by the counting unit is greater than or equal to the preset number of errors. Threshold, if If it is greater than or equal to, the abnormal signal of the corresponding cylinder injector will be output.

Preferably, the rail pressure detection unit includes a rail pressure sensor provided on the high-pressure common rail pipe.

In a preferred manner, the counting unit includes four counters, and the four counters are respectively the cumulative number of errors reported by the four cylinders.

Preferably, it further includes a preset unit electrically connected to the electronic control unit, the preset unit presets a calibration rail pressure deviation according to a map table calibrated by the engine speed and the fuel injection amount, and the calibration rail pressure deviation is preset. The pressure deviation is used as the rail pressure deviation threshold.

Preferably, the preset unit presets the correction coefficient, then the electronic control unit searches for the correction coefficient according to the actual rail pressure at the initial stage of injection of each cylinder, and calculates the product of the correction coefficient and the deviation of the calibration rail pressure as the rail pressure deviation threshold.

After adopting the above-mentioned technical scheme, the beneficial effects of the present invention are:

Due to the method and system of the present invention for judging the working state of the injector in the initial stage of diesel engine startup, in the initial stage of diesel engine startup, the real-time injection rail pressure of each cylinder is obtained by detecting the actual rail pressure in the initial stage of injection and the lowest rail pressure in the injection process of each cylinder. pressure deviation, compare the real-time injection rail pressure deviation with the preset rail pressure deviation threshold, when the real-time injection rail pressure deviation is less than or equal to the rail pressure deviation threshold, the condition of the cylinder reporting an error once is satisfied, and the cylinder is used to accumulate the number of errors When the accumulated number of errors reported by the counter is greater than or equal to the preset number of times threshold, it indicates that the injector of this cylinder is in an abnormal state, an error is reported and the counter is cleared. Therefore, the present invention can judge the working state of the fuel injector at the initial stage of engine starting, and effectively lock whether the failure to start the diesel engine is related to the fuel injector.

Description of drawings

Fig. 1 is the flow chart of the method for judging the working state of the fuel injector in the initial stage of diesel engine startup according to the present invention;

Fig. 2 is the logic relation diagram of the method for judging the working state of the fuel injector in the initial stage of diesel engine startup according to the present invention;

Fig. 3 is the principle block diagram of the fan control system in the vehicle regeneration mode of the present invention;

Fig. 4 is the structural representation of the high-pressure common rail pipe of the present invention;

In the picture: 1- high pressure common rail pipe, 2- rail pressure sensor, 3- fuel injector.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1:

As shown in Figure 1 and Figure 2, a method for judging the working state of a fuel injector in the initial stage of starting a diesel engine includes the following steps:

Step S1, obtaining the engine running state;

Step S2, judging whether the engine running state is the starting stage;

Step S3, if yes, obtain the actual rail pressure at the initial stage of injection and the lowest rail pressure during the injection process of each cylinder;

Step S4, using the formula to obtain the real-time injection rail pressure deviation of each cylinder, the formula is: real-time injection rail pressure deviation=actual rail pressure at the initial stage of injection-minimum rail pressure during injection;

Step S5, judging whether the real-time injection rail pressure deviation of each cylinder is less than or equal to a preset rail pressure deviation threshold;

Step S6, if yes, report an error once, and the counter for accumulating the number of times of error reporting of each cylinder is accumulated;

Step S7, judging whether the accumulated number of times is greater than or equal to a preset number of times threshold;

Step S8, if yes, output a failure signal of the fuel injector of the corresponding cylinder, and clear the corresponding counter.

After the method of the invention is adopted, in the initial stage of diesel engine starting, by detecting the actual rail pressure in the initial stage of injection and the lowest rail pressure in the injection process of each cylinder, and through the actual rail pressure in the initial stage of injection and the lowest rail pressure in the injection process, the actual rail pressure in the ignition process of a certain cylinder can be obtained. The real-time rail pressure deviation compares the real-time rail pressure deviation with the rail pressure deviation threshold to judge the working state of the injector in the initial stage of diesel engine startup, which can effectively lock whether the failure of diesel engine startup is related to the injector. In addition, the method of the present invention does not increase the original cost, is easy to operate, and has low cost.

In this embodiment: before step S5, the following steps are also included:

Get engine speed and fuel injection quantity;

Find the pre-calibrated map table according to the engine speed and fuel injection quantity, and find the calibration rail pressure deviation;

Use the calibrated rail pressure deviation as the rail pressure deviation threshold.

By detecting the engine speed and fuel injection amount, the rail pressure deviation threshold is set, so that the detection of the injector status of each cylinder at the initial stage of starting is combined with the real-time working conditions, and the detection is more accurate and reliable.

In this embodiment: after the step of finding the calibration rail pressure deviation, the following steps are also included:

According to the actual rail pressure at the initial stage of injection of each cylinder, find the pre-calibrated correction curve, and find the correction coefficient;

Then the rail pressure deviation threshold is the product of the calibration rail pressure deviation and the correction coefficient.

The correction coefficient is obtained from the actual rail pressure at the initial stage of injection of each cylinder to correct the calibration rail pressure deviation, so as to obtain the rail pressure deviation threshold consistent with the actual working conditions, so that the detection of the injector status of each cylinder at the initial stage of starting is more accurate and reliable.

Embodiment 2:

As shown in Figure 3, a system for judging the working state of an injector in the initial stage of diesel engine startup includes an electronic control unit, and also includes a state detection unit, a rail pressure detection unit, a fault diagnosis unit and a counting unit that are electrically connected to the electronic control unit. , the state detection unit is used to judge whether the engine is running to the starting stage; the rail pressure detection unit is used to obtain the actual rail pressure at the initial stage of injection and the lowest rail pressure during the injection process of each cylinder, and according to the actual rail pressure at the initial stage of injection and the minimum rail pressure during the injection process The minimum rail pressure is used to obtain the real-time injection rail pressure deviation of each cylinder; the fault diagnosis and detection unit compares the real-time injection rail pressure deviation of each cylinder with the preset rail pressure deviation threshold. When the real-time injection rail pressure deviation is less than or equal to the preset When the rail pressure deviation threshold, the corresponding cylinder error signal is issued once; the counting unit is used to accumulate the number of errors reported by each cylinder; the electronic control unit judges whether the number of errors accumulated by the counting unit is greater than or equal to the preset number of errors. Cylinder injector abnormal signal. This counting unit includes four counters, and the four counters are the accumulative error times of the four cylinders respectively.

As shown in FIG. 4 , the rail pressure detection unit includes a rail pressure sensor 2 provided on the high-pressure common rail tube.

In the system of the present invention for judging the working state of the fuel injector in the initial stage of diesel engine startup, when the state detection unit detects that the diesel engine is in the startup stage, the electronic control unit controls the rail pressure detection unit to collect the actual rail pressure at the initial stage of injection of each cylinder and the lowest rail pressure during the injection process. Rail pressure, after calculating the difference between the two, the real-time injection rail pressure deviation of each cylinder is obtained. Specifically, the rail pressure of each cylinder is collected by the rail pressure sensor. After the real-time injection rail pressure deviation is transmitted to the electronic control unit, the electronic control unit activates the fault diagnosis unit to compare the real-time injection rail pressure deviation with a preset rail pressure deviation threshold. When the real-time injection rail pressure deviation is less than or equal to the rail pressure deviation threshold, the condition of one error report is satisfied, and the electronic control unit controls the counter of the corresponding cylinder of the counting unit to accumulate the number of error reports. At the same time, the electronic control unit judges whether the number of error reports accumulated by the counter is greater than or equal to the preset number of times threshold. If it is greater than or equal to, it indicates that the cylinder injector is in an abnormal state, and the cylinder counter is cleared. It can be seen that the system of the present invention can accurately lock the working state of each fuel injector at the initial stage of diesel engine starting, and can quickly lock whether it is related to the fuel injector when the starting is abnormal.

As shown in Figure 3, the system also includes a preset unit that is electrically connected to the electronic control unit. The preset unit is based on the map table calibrated by the engine speed and the fuel injection amount, and the preset calibrated rail pressure deviation and the calibrated rail pressure deviation. as the rail pressure deviation threshold.

The preset unit sets the calibration rail pressure deviation related to the engine speed and the fuel injection amount as the rail pressure deviation threshold value, which improves the reliability of the system detection and makes the current real-time injection rail pressure deviation of each cylinder related to the engine operating conditions .

In order to further improve the reliability of the system, the preset unit presets the correction coefficient, the electronic control unit searches for the correction coefficient according to the actual rail pressure at the initial stage of injection of each cylinder, and takes the product of the correction coefficient and the calibration rail pressure deviation as the rail pressure deviation threshold .

The above-mentioned preferred embodiments of the present invention are not intended to limit the present invention. Any modification made within the spirit and principle of the present invention is equivalent to a method and system for judging the working state of the fuel injector in the initial stage of diesel engine startup. The improvements, etc., should be included within the protection scope of the present invention.

Claims (4)

1. a method for judging the working state of fuel injector in the initial stage of diesel engine startup, is characterized in that, comprises the following steps: Get the engine running status; Determine whether the engine running state is the starting stage; If yes, obtain the actual rail pressure at the initial stage of injection and the lowest rail pressure during the injection process of each cylinder; Use the formula to obtain the real-time injection rail pressure deviation of each cylinder, the formula is: real-time injection rail pressure deviation = actual rail pressure at the initial stage of injection - minimum rail pressure during injection; Determine whether the real-time injection rail pressure deviation of each cylinder is less than or equal to the preset rail pressure deviation threshold; If it is, it will report an error once, and the counter used to accumulate the number of errors reported by each cylinder is accumulated; Determine whether the accumulated number of times is greater than or equal to the preset number of times threshold; If it is, output the failure signal of the injector of the corresponding cylinder, and clear the corresponding counter; Before the step of judging whether the real-time injection rail pressure difference of each cylinder is less than or equal to the preset rail pressure deviation threshold value, the following steps are also included: Get engine speed and fuel injection quantity; Find the pre-calibrated map table according to the engine speed and fuel injection quantity, and find the calibration rail pressure deviation; using the calibrated rail pressure deviation as the rail pressure deviation threshold; After the step of calibrating the rail pressure deviation is found, the following steps are also included: According to the actual rail pressure at the initial stage of injection of each cylinder, find the pre-calibrated correction curve, and find the correction coefficient; Then the rail pressure deviation threshold is the product of the calibration rail pressure deviation and the correction coefficient. 2. A system for judging the working state of a fuel injector in the initial stage of diesel engine startup, comprising an electronic control unit, and characterized in that it also includes electrically connected to the electronic control unit respectively: a state detection unit, the state detection unit is used for judging whether the engine runs to the start stage; Rail pressure detection unit, the rail pressure detection unit is used to obtain the actual rail pressure at the initial stage of injection and the minimum rail pressure during the injection process of each cylinder, and obtain the real-time rail pressure of each cylinder according to the actual rail pressure at the initial stage of injection and the minimum rail pressure during the injection process Injection rail pressure deviation; A fault diagnosis unit, the fault diagnosis and detection unit compares the real-time injection rail pressure deviation of each cylinder with a preset rail pressure deviation threshold, and when the real-time injection rail pressure deviation is less than or equal to the preset rail pressure deviation threshold, sends out the corresponding cylinder Error signal once; a counting unit, which is used for accumulating the number of errors reported by each cylinder; The electronic control unit judges whether the number of error reports accumulated by the counting unit is greater than or equal to a preset error number threshold, and if it is greater than or equal to, an abnormal signal of the corresponding cylinder injector is output; a preset unit, the preset unit presets the calibration rail pressure deviation according to the map table of the engine speed and the fuel injection amount, and the calibrated rail pressure deviation is used as the rail pressure deviation threshold; The preset unit presets the correction coefficient, then the electronic control unit searches for the correction coefficient according to the actual rail pressure at the initial stage of injection of each cylinder, and takes the product of the correction coefficient and the calibration rail pressure deviation as the rail pressure deviation threshold. 3 . The system for judging the working state of the fuel injector in the initial stage of diesel engine startup according to claim 2 , wherein the rail pressure detection unit comprises a rail pressure sensor provided on the high-pressure common rail pipe. 4 . 4 . The system of claim 3 , wherein the counting unit comprises four counters, and the four counters are respectively the cumulative number of errors reported by the four cylinders. 5 .

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