1. A method for diagnosing leakage faults of a pressure release valve of an oil rail is characterized by comprising the following steps:

detecting the operation condition of the engine and determining whether the engine is in a reverse dragging state;

monitoring the working state of the electromagnetic valve of the high-pressure oil pump, and reading real-time working condition parameters of the electromagnetic valve;

and comparing the real-time working condition parameters with the set parameter threshold value, and judging whether the leakage fault exists in the oil rail pressure release valve.

2. The method for diagnosing leakage faults of the oil rail pressure release valve according to claim 1, wherein when the high-pressure oil pump electromagnetic valve is a high-pressure oil pump oil inlet electromagnetic valve, the working state of the high-pressure oil pump oil inlet electromagnetic valve is monitored, the real-time working condition parameters are read, the real-time working condition parameters and the set parameter threshold are compared, and whether the leakage faults exist in the oil rail pressure release valve is judged, including:

reading feedback current of the oil inlet electromagnetic valve of the high-pressure oil pump for maintaining stable pressure;

comparing the feedback current with a set feedback current threshold;

and if the feedback current is larger than the feedback current threshold value, judging that the leakage fault exists in the oil rail pressure release valve, and if the feedback current is smaller than or equal to the feedback current threshold value, judging that the leakage fault does not exist in the oil rail pressure release valve.

3. The method for diagnosing the leakage fault of the oil rail pressure release valve according to claim 2, characterized by further comprising an anti-shake detection step when comparing the feedback current with the feedback current threshold, wherein in an anti-shake detection time, if the feedback current is larger than the feedback current threshold, it is determined that the leakage fault exists in the oil rail pressure release valve, and if the feedback current is smaller than or equal to the feedback current threshold, it is determined that the leakage fault does not exist in the oil rail pressure release valve.

4. The method for diagnosing leakage faults of the oil rail pressure release valve according to claim 1, wherein when the high-pressure oil pump electromagnetic valve is a high-pressure oil pump oil outlet electromagnetic valve, the working state of the high-pressure oil pump oil outlet electromagnetic valve is monitored, the real-time working condition parameters are read, the real-time working condition parameters and the set parameter threshold are compared, and whether the leakage faults exist in the oil rail pressure release valve is judged, including:

reading the power-on time advance angle of the high-pressure oil pump oil outlet electromagnetic valve maintaining the stable pressure;

comparing the power-on time advance angle with a set power-on time advance angle threshold;

and if the power-up time advance angle is larger than the power-up time advance angle threshold, judging that the oil rail pressure release valve has a leakage fault, and if the power-up time advance angle is smaller than or equal to the power-up time advance angle threshold, judging that the oil rail pressure release valve does not have a leakage fault.

5. The method for diagnosing the leakage fault of the oil rail pressure release valve according to claim 1, characterized in that before the working condition parameters of the high-pressure oil pump electromagnetic valve are read, the high-pressure oil pump electromagnetic valve is confirmed to enter a closed-loop control mode, and the rail pressure is maintained stable.

6. The method for diagnosing the leakage fault of the pressure release valve of the oil rail according to claim 1, characterized by detecting the operating condition of the engine, determining whether the engine is in a drag-down state, judging the working condition of an automobile if the engine is in the drag-down state, and diagnosing after the working condition of the engine is met next time if the engine is not in the drag-down state.

7. The method for diagnosing the leakage fault of the pressure release valve of the oil rail according to claim 6, wherein the judgment of the working condition of the automobile comprises that an accelerator is qualified, an oil injection quantity is qualified, a torque is qualified, and a rail pressure is stable.

8. The utility model provides a rail relief valve leaks fault diagnostic device which characterized in that includes:

the monitoring module is used for monitoring whether the engine is in a dragging state, monitoring the working state of the electromagnetic valve of the high-pressure oil pump and reading real-time working condition parameters;

and the judging module is used for comparing the real-time working condition parameters with the set parameter threshold value and judging whether the leakage fault exists in the oil rail pressure release valve.

9. The leakage fault diagnosis device for the oil rail pressure release valve according to claim 8, wherein when the high-pressure oil pump electromagnetic valve is a high-pressure oil pump oil inlet electromagnetic valve:

the monitoring module is used for reading feedback current of the oil inlet electromagnetic valve of the high-pressure oil pump for maintaining stable voltage;

the judging module is used for comparing the feedback current with a set feedback current threshold, if the feedback current is larger than the feedback current threshold, judging that the leakage fault exists in the oil rail pressure release valve, and if the feedback current is smaller than or equal to the feedback current threshold, judging that the leakage fault does not exist in the oil rail pressure release valve.

10. The leakage fault diagnosis device for the pressure release valve of the oil rail according to claim 8, wherein when the electromagnetic valve of the high-pressure oil pump is an electromagnetic valve for oil outlet of the high-pressure oil pump:

the monitoring module is used for reading the power-on time advance angle of the high-pressure oil pump oil outlet electromagnetic valve for maintaining stable pressure;

the judgment module is used for comparing the pre-angle of the power-on time with a set pre-angle threshold of the power-on time, judging that the oil rail pressure release valve has a leakage fault if the pre-angle of the power-on time is greater than the pre-angle threshold of the power-on time, and judging that the oil rail pressure release valve does not have the leakage fault if the pre-angle of the power-on time is less than or equal to the set pre-angle threshold of the power-on time.

Background

Along with the continuous upgrading of emission regulations, the precision and the requirement of an engine control system are continuously improved, an electric control high-pressure common rail system is a set of fuel system control device which is widely used in the field of diesel engine control at present, the system not only can achieve higher injection pressure, but also can independently and flexibly control the fuel injection timing, the injection pulse width and the fuel injection quantity, so that the diesel engine can be combusted under different working conditions to achieve ideal working conditions, an ideal injection effect is realized, and the fuel economy and the engine power performance are greatly improved while the emission is reduced. In a high-pressure common rail control system, an oil rail pressure relief valve is a very important part in the system, and when the rail pressure in an oil rail exceeds a limit value, the pressure relief of the rail pressure in the oil rail can be realized, and the physical protection and limp home function of the common rail system are realized. The oil rail pressure relief valve can be divided into an electric control pressure relief valve and a mechanical pressure relief valve, the electric control pressure relief valve is controlled by an engine ECU, and the ECU sends a control instruction to the electric control pressure relief valve to open or close according to rail pressure control and system working condition requirements; and the mechanical pressure relief valve protects the rail pressure in the rail pipe through the action of the gasket and the spring, and when the rail pressure in the rail pipe exceeds the acting force of the spring, the mechanical pressure relief valve is opened to relieve the pressure. The leakage fault of the oil rail pressure release valve can occur due to aging, and rail pressure fluctuation can be caused if the pressure release valve leaks, so that the injection precision is reduced, the combustion is deteriorated, and the emission is influenced; in addition, leakage of the pressure relief valve can cause high-pressure fuel to flow back to the fuel tank, energy is wasted, and fuel quality is also affected, so that accurate identification and diagnosis of leakage faults of the fuel rail pressure relief valve are needed.

In the related art, whether the relief valve is in failure or not is diagnosed by comparing the flow of the high-pressure pump or the fuel pressure in the common rail with a corresponding threshold value, but the method only performs valve flushing to judge whether the mechanical overpressure valve is in failure that the mechanical overpressure valve should be opened but cannot be opened by opening and pressurizing a metering valve.

Disclosure of Invention

The application provides a fault diagnosis method and device for an oil rail pressure release valve, which are used for solving the problems that the condition that the oil rail pressure release valve is slightly leaked cannot be detected in the prior art, the detection cannot be carried out in the normal operation process of a system, and the bad influence on the driving feeling can be caused.

In a first aspect, the present application provides a method for diagnosing a fault of a pressure release valve of an oil rail, where the method includes the following steps:

detecting the operation condition of the engine and determining whether the engine is in a reverse dragging state;

monitoring the working state of the electromagnetic valve of the high-pressure oil pump, and reading real-time working condition parameters of the electromagnetic valve;

and comparing the real-time working condition parameters with the set parameter threshold value, and judging whether the leakage fault exists in the oil rail pressure release valve.

In some embodiments, when the high-pressure oil pump solenoid valve is high-pressure oil pump oil feed solenoid valve, the control high-pressure oil pump oil feed solenoid valve operating condition reads real-time operating mode parameter, contrast real-time operating mode parameter with the parameter threshold value that sets for judges whether there is the trouble of revealing in the oil rail relief valve, include:

reading feedback current of the oil inlet electromagnetic valve of the high-pressure oil pump for maintaining stable pressure;

comparing the feedback current with a set feedback current threshold;

and if the feedback current is larger than the feedback current threshold value, judging that the leakage fault exists in the oil rail pressure release valve, and if the feedback current is smaller than or equal to the feedback current threshold value, judging that the leakage fault does not exist in the oil rail pressure release valve.

In some embodiments, when the feedback current is compared with the feedback current threshold, an anti-shake detection step is further included, in an anti-shake detection time, if the feedback current is greater than the feedback current threshold, it is determined that a leakage fault exists in the oil rail pressure release valve, and if the feedback current is less than or equal to the feedback current threshold, it is determined that a leakage fault does not exist in the oil rail pressure release valve.

In some embodiments, when the high-pressure oil pump solenoid valve is high-pressure oil pump outlet solenoid valve, monitor high-pressure oil pump outlet solenoid valve operating condition, read the real-time operating mode parameter, compare the real-time operating mode parameter with the parameter threshold value that sets for, judge whether there is the trouble of revealing in the oil rail relief valve, include:

reading the power-on time advance angle of the high-pressure oil pump oil outlet electromagnetic valve maintaining the stable pressure;

comparing the power-on time advance angle with a set power-on time advance angle threshold;

and if the power-up time advance angle is larger than the power-up time advance angle threshold, judging that the oil rail pressure release valve has a leakage fault, and if the power-up time advance angle is smaller than or equal to the power-up time advance angle threshold, judging that the oil rail pressure release valve does not have a leakage fault.

In some embodiments, when comparing the power-on time advance angle with the power-on time advance angle threshold, the method further includes an anti-shake detection step, and in the anti-shake detection time, if the power-on time advance angle is greater than the power-on time advance angle threshold, it is determined that the oil rail pressure release valve has a leakage fault, and if the power-on time advance angle is less than or equal to the power-on time advance angle threshold, it is determined that the oil rail pressure release valve does not have a leakage fault.

In some embodiments, before the operating condition parameter of the high-pressure oil pump electromagnetic valve is read, the high-pressure oil pump electromagnetic valve is confirmed to enter a closed-loop control mode, so that the rail pressure is maintained stable.

In some embodiments, the operating condition of the engine is detected, whether the engine is in a towing state or not is determined, if the engine is in the towing state, the operating condition of the vehicle is determined, and if the engine is not in the towing state, the vehicle is diagnosed after the next time the operating condition of the engine is met.

In some embodiments, the automobile working condition judgment comprises that an accelerator is qualified, an oil injection quantity is qualified, a torque is qualified, and a rail pressure is stable.

In a second aspect, the present application provides a fault diagnosis device for a rail relief valve, the device comprising:

the monitoring module is used for monitoring whether the engine is in a dragging state, monitoring the working state of the electromagnetic valve of the high-pressure oil pump and reading real-time working condition parameters of the electromagnetic valve;

and the judging module is used for comparing the real-time working condition parameters with the set parameter threshold value and judging whether the leakage fault exists in the oil rail pressure release valve.

In some embodiments, when the high-pressure oil pump solenoid valve is a high-pressure oil pump oil inlet solenoid valve, the monitoring module is configured to read a feedback current of the high-pressure oil pump oil inlet solenoid valve maintaining stable voltage;

the judging module is used for comparing the feedback current with a set feedback current threshold, if the feedback current is larger than the feedback current threshold, judging that the leakage fault exists in the oil rail pressure release valve, and if the feedback current is smaller than or equal to the feedback current threshold, judging that the leakage fault does not exist in the oil rail pressure release valve.

In some embodiments, the determining module compares the feedback current with the feedback current threshold, and further includes an anti-shake detection step, in an anti-shake detection time, if the determining module determines that the feedback current is greater than the feedback current threshold, it is determined that the oil rail pressure release valve has a leakage fault, and if the determining module determines that the feedback current is less than or equal to the feedback current threshold, it is determined that the oil rail pressure release valve does not have a leakage fault.

In some embodiments, when the high-pressure oil pump electromagnetic valve is a high-pressure oil pump oil outlet electromagnetic valve, the monitoring module is configured to read a power-on timing advance angle of the high-pressure oil pump oil outlet electromagnetic valve for maintaining stable pressure;

the judgment module is used for comparing the pre-angle of the power-on time with a set pre-angle threshold of the power-on time, judging that the oil rail pressure release valve has a leakage fault if the pre-angle of the power-on time is greater than the pre-angle threshold of the power-on time, and judging that the oil rail pressure release valve does not have the leakage fault if the pre-angle of the power-on time is less than or equal to the set pre-angle threshold of the power-on time.

In some embodiments, the determining module compares the power-on time advance angle with the power-on time advance angle threshold, and further includes an anti-shake detection step, in an anti-shake detection time, if the determining module determines that the power-on time advance angle is greater than the power-on time advance angle threshold, it is determined that the oil rail pressure release valve has a leakage fault, and if the determining module determines that the power-on time advance angle is less than or equal to the power-on time advance angle threshold, it is determined that the oil rail pressure release valve has no leakage fault.

In some embodiments, before the monitoring module reads the operating condition parameters of the high-pressure oil pump electromagnetic valve, it is determined that the high-pressure oil pump electromagnetic valve enters a closed-loop control mode, so that the rail pressure is maintained stable.

In some embodiments, the monitoring module monitors the operating condition of the engine, determines whether the engine is in a towing backward state, determines the operating condition of the vehicle if the engine is in the towing backward state, and diagnoses the engine after the operating condition of the engine is met next time if the engine is not in the towing backward state.

In some embodiments, the automobile working condition judgment monitored by the monitoring module comprises that an accelerator is qualified, an oil injection quantity is qualified, a torque is qualified, and a rail pressure is stable.

The application provides a leakage fault diagnosis method and device for an oil rail pressure release valve, which are used for reading real-time working condition parameters of a high-pressure oil pump electromagnetic valve by monitoring the working state of the high-pressure oil pump electromagnetic valve, comparing the real-time working condition parameters with set parameter thresholds, judging whether leakage faults exist in the oil rail pressure release valve or not, and realizing the diagnosis of the leakage faults of the oil rail pressure release valve.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a high pressure common rail system block diagram;

fig. 2 is a schematic flow chart of a method for diagnosing a leakage fault of a pressure release valve of an oil rail according to an embodiment of the present application;

FIG. 3 is a flow chart of closed-loop detection of an oil inlet electromagnetic valve of a high-pressure oil pump;

FIG. 4 is a working schematic diagram of an oil outlet electromagnetic valve of the high-pressure oil pump;

FIG. 5 is a flow chart of the closed loop detection of the oil outlet electromagnetic valve of the high-pressure oil pump;

fig. 6 is a schematic block diagram of a leakage fault diagnosis device for a rail pressure relief valve according to an embodiment of the present application.

In the figure, 1-a fuel tank, 2-a rough filter, 3-a fine filter, 4-a low-pressure oil transfer pump, 5-a high-pressure oil pump, 6-a high-pressure oil pump electromagnetic valve (an oil inlet electromagnetic valve of the high-pressure oil pump or an oil outlet electromagnetic valve of the high-pressure oil pump), 7-a rail pressure sensor, 8-a common rail pipe, 9-a rail pressure release valve (an oil rail electric control pressure release valve or an oil rail mechanical pressure release valve) and 10-an oil injector.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The flow diagrams depicted in the figures are merely illustrative and do not necessarily include all of the elements and operations/steps, nor do they necessarily have to be performed in the order depicted. For example, some operations/steps may be decomposed, combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.

The embodiment of the application provides a leakage fault diagnosis method and device for an oil rail pressure release valve, which can diagnose whether the leakage fault exists in the oil rail pressure release valve through real-time working condition parameters of a high-pressure oil rail electromagnetic valve.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

To better explain the method for diagnosing a failure of the rail relief valve, first, the control of the rail pressure will be explained.

Referring to fig. 1, a high pressure common rail system is shown in block diagram form. The high-pressure oil pump electromagnetic valve 6, the rail pressure sensor 7, the oil rail electric control pressure relief valve 9 and the oil injector 10 are controlled by the ECU. The high-pressure oil pump 5 compresses fuel oil in a low-pressure oil way and inputs the compressed fuel oil into the common rail pipe 8, the rail pressure sensor 7 is responsible for monitoring the rail pressure state of the fuel oil in the common rail pipe 8, reference basis is provided for accurately controlling rail pressure balance, and the ECU controls the oil injector 10 to inject oil, so that combustion is realized in the cylinder.

In the high-pressure common rail system, the high-pressure oil pump electromagnetic valve can be a high-pressure oil pump oil inlet electromagnetic valve and also can be a high-pressure oil pump oil outlet electromagnetic valve, and only one of the high-pressure oil pump electromagnetic valves needs to be selected to control the oil quantity.

Referring to fig. 2, fig. 2 is a schematic flow chart of a method for diagnosing a leakage fault of a rail relief valve according to an embodiment of the present application, where the method includes the following steps,

s1, detecting the operation condition of the engine and determining whether the engine is in a back-dragging state;

s2, monitoring the working state of the high-pressure oil pump electromagnetic valve, and reading the real-time working condition parameters;

and S3, comparing the real-time working condition parameters of the electromagnetic valve of the high-pressure oil pump with the set parameter threshold value, and judging whether the leakage fault exists in the oil rail pressure release valve.

It is worth to be noted that when the high-pressure oil pump electromagnetic valve is a high-pressure oil pump oil inlet electromagnetic valve, the real-time parameter is feedback current, and when the high-pressure oil pump electromagnetic valve is a high-pressure oil pump oil outlet electromagnetic valve, the real-time parameter is an advance angle of power-on time.

The specific method of diagnosis will be described below by way of specific embodiments.

Referring to fig. 3, fig. 3 is a flow chart of closed-loop detection of the oil inlet electromagnetic valve of the high-pressure oil pump.

Firstly, detecting the operating condition of an engine, determining whether the engine is in a towing state, and if the engine is not in the towing state, diagnosing the engine after the next operating condition of the engine is met; if the engine is in a back-dragging state, judging the working condition of the automobile, wherein the qualified conditions of the working condition of the automobile comprise that the accelerator is 0, the fuel injection quantity is 0, the torque is 0 and the rail pressure is stable, and the qualified monitoring module of the working condition of the automobile starts to monitor the working state of the electromagnetic valve of the high-pressure oil pump

After the working condition of the automobile reaches a qualified state, rail pressure is maintained in a stable state, then the feedback current of the oil inlet electromagnetic valve of the high-pressure oil pump which maintains the voltage stabilization at present is read, and the read feedback current is compared with a set feedback current threshold value.

It is worth to say that, the high-pressure oil pump oil inlet electromagnetic valve is a solenoid type electromagnet, the solenoid type electromagnet is controlled in a closed loop mode through PWM (pulse width modulation), so that feedback current is generated, the opening degree of the high-pressure oil pump oil inlet electromagnetic valve is controlled through the feedback current, so that the fuel oil amount entering a plunger cavity of the high-pressure oil pump is controlled, the fuel oil in the plunger cavity of the high-pressure oil pump can be compressed by the high-pressure oil pump and enters a common rail, and therefore rail pressure is adjusted.

Further, a specific adjusting mode is that when the rail pressure is too low, the feedback current is increased, so that the opening degree of the high-pressure oil pump oil inlet electromagnetic valve is increased, the larger the opening of the high-pressure oil pump oil inlet electromagnetic valve is, the more fuel oil enters the plunger cavity of the high-pressure oil pump, the more fuel oil amount compressed by the high-pressure oil pump and enters the common rail pipe is, and the higher the rail pressure of the fuel oil in the common rail pipe is. When the rail pressure is too high, the feedback current is reduced, so that the opening degree of an oil inlet electromagnetic valve of the high-pressure oil pump is reduced, the fuel entering a plunger cavity of the high-pressure oil pump is reduced, the amount of the fuel compressed by the high-pressure oil pump and entering the common rail pipe is reduced, and the rail pressure of the fuel in the common rail pipe is also lower.

It is worth to be noted that, in the sliding process of the fuel release door in the driving, under normal conditions, in order to maintain stable rail pressure, the oil inlet electromagnetic valve of the high-pressure oil pump should be in a closed state or work with a minimum opening at the moment, if the read feedback current is greater than the feedback current threshold value, it is indicated that the current rail pressure is low, the feedback current needs to be increased, so that the opening of the oil inlet electromagnetic valve of the high-pressure oil pump is increased, the fuel quantity entering a plunger cavity of the high-pressure oil pump is increased, the fuel quantity compressed by the high-pressure oil pump and entering a common rail pipe is also increased, the purpose of increasing the rail pressure is achieved, and the rail pressure is maintained stable, therefore, the read feedback current is greater than the feedback current threshold value, it is determined that the leakage fault exists in the oil rail pressure release valve, the leakage fault is reported to remind a driver to perform maintenance check, if the feedback current is less than or equal to the feedback current threshold value, it is indicated that the rail pressure is stable at the moment, the oil outlet electromagnetic valve of the high-pressure oil pump is in a closed state or works at a tiny power-on advance angle, so that the oil rail pressure release valve is judged to have no leakage fault, and the next detection is waited.

It should be noted that, in order to prevent the occurrence of the misjudgment condition, when the feedback current is compared with the feedback current threshold, an anti-shake detection step is further added, the detection is performed in a stable state of the automobile, and the situation that the static leakage amount of the oil rail pressure release valve is increased due to vehicle shake can be eliminated, so that the fault misjudgment condition is avoided.

Referring to fig. 4 and 5, fig. 4 is a working principle diagram of the oil outlet electromagnetic valve of the high-pressure oil pump. Fig. 5 is a closed-loop detection flow chart of the oil outlet electromagnetic valve of the high-pressure oil pump.

Referring to fig. 5, in the detection process, firstly, the operating condition of the engine is detected, whether the engine is in a towing state or not is determined, and if the engine is not in the towing state, the engine is diagnosed after the operating condition of the engine is met next time; if the engine is in a back-dragging state, judging the working condition of the automobile, wherein the qualified conditions of the working condition of the automobile comprise that the accelerator is 0, the fuel injection quantity is 0, the torque is 0 and the rail pressure is stable, and the qualified monitoring module of the working condition of the automobile starts to monitor the working state of the electromagnetic valve of the high-pressure oil pump

And after the working condition of the automobile reaches a qualified state, determining that the oil outlet electromagnetic valve of the high-pressure oil pump enters a closed-loop control mode, keeping the rail pressure in a stable state, reading the power-on time advance angle of the oil outlet electromagnetic valve of the high-pressure oil pump which currently maintains stable pressure, and comparing the read power-on time advance angle with a set power-on time advance angle threshold.

It should be noted that, referring to fig. 4, in the high-pressure common rail system, the high-pressure oil pump discharge solenoid valve is an on-off valve, and the on-off of the high-pressure oil pump discharge solenoid valve is driven by a PEAK-HOLD (PEAK HOLD function). The working principle of the high-pressure oil pump oil outlet electromagnetic valve is that in the descending process of a high-pressure oil pump plunger, the high-pressure oil pump oil outlet electromagnetic valve is opened, low-pressure oil way fuel oil is sucked into a high-pressure cavity, in the ascending process of the high-pressure oil pump plunger, redundant fuel oil is pushed out of the high-pressure cavity, then the high-pressure oil pump oil outlet electromagnetic valve is closed, so that an oil return channel is closed, the fuel oil left in the high-pressure cavity overcomes the acting force of a spring and is input into a common rail pipe to realize the adjustment of rail pressure, therefore, the moment of controlling the high-pressure oil pump oil outlet electromagnetic valve to be switched on is the moment of power-on, namely the moment of power-on and power-off, the adjustment of the oil pumping quantity can be realized, the specific adjustment mode is that the high-pressure oil pump oil outlet electromagnetic valve is opened, the low-pressure oil way fuel oil is sucked into the high-pressure cavity, in the ascending process of the high-pressure oil pump plunger, the redundant fuel oil is pushed out of the high-pressure oil pump oil outlet electromagnetic valve is adjusted according to the oil flow quantity required for maintaining and pressure stabilization, when the fuel oil reserved in the high-pressure cavity meets the requirement of maintaining the stable pressure, the oil outlet electromagnetic valve of the high-pressure oil pump is closed. When the rail pressure is too low, the high-pressure oil pump oil outlet electromagnetic valve is electrified in advance in the ascending process of the high-pressure oil pump plunger to be closed, so that more fuel oil is reserved in the high-pressure cavity and then is input into the common rail pipe, and the rail pressure is increased.

Further, a specific adjusting mode is that when the rail pressure is too high, the high-pressure oil pump oil outlet electromagnetic valve is electrified later in the ascending process of the high-pressure oil pump plunger to be closed, so that a small amount of fuel oil is reserved in the high-pressure cavity and then is input into the common rail pipe, and the rail pressure is reduced. And after the high-pressure oil pump electromagnetic valve is closed, the whole plunger piston is in a closed state in the ascending stage, the relation with the power-on pulse width is not large, and the relation with the rotating speed is irrelevant, because the high-pressure fuel oil in the high-pressure cavity can close the valve top, and the high-pressure fuel oil can be re-opened only in the descending stage of the plunger piston, when the closed-loop control state of the high-pressure oil pump oil outlet electromagnetic valve is discussed later, only the difference of the power-on time advance angle is considered, and the influence of the power-on pulse width and the rotating speed is ignored.

It is worth to be noted that, in order to maintain the rail pressure stable in the normal state, the oil outlet electromagnetic valve of the high-pressure oil pump should be in the closed state or operate at a very small power-on advance angle, if the read power-on time advance angle is larger than the power-on time advance angle threshold, which indicates that the rail pressure is too low at the moment, the high-pressure oil pump oil outlet electromagnetic valve needs to be powered on in advance in the ascending process of the high-pressure oil pump plunger to be closed earlier, thereby reserving a large amount of fuel oil in the high-pressure cavity and then inputting the fuel oil into the common rail pipe, achieving the purpose of increasing the rail pressure to maintain the rail pressure to be stable, therefore, if the read power-on time advance angle is larger than the power-on time advance angle threshold value, the oil rail pressure release valve is judged to have leakage fault, and reporting a leakage fault, and if the feedback current is less than or equal to the feedback current threshold value, judging that the leakage fault does not exist in the oil rail pressure release valve, and waiting for the next detection.

It should be noted that, in order to prevent the occurrence of the misjudgment condition, when the power-on time advance angle is compared with the power-on time advance angle threshold, an anti-shake detection step is added, and detection is performed in a stable state of the vehicle, so that the situation that the static leakage amount of the oil rail pressure release valve is increased due to vehicle body shake can be eliminated, and thus the situation of fault misjudgment is avoided.

The fault diagnosis method comprises the steps of firstly, defaulting that a rail pressure sensor signal is stable and has no fault, enabling an oil injector to work normally and have no fault, then adjusting a high-pressure oil pump electromagnetic valve based on rail pressure closed-loop control, and judging whether a leakage fault exists in an oil rail pressure release valve or not by comparing a real-time working condition parameter for controlling the real-time opening degree of the high-pressure oil pump electromagnetic valve with a set threshold value difference value. The method for diagnosing the leakage fault of the oil rail pressure release valve by using the real-time working condition parameters of the high-pressure oil pump electromagnetic valve is suitable for the oil rail electric control pressure release valve and the oil rail mechanical pressure release valve, can diagnose fine leakage in advance, and avoids the dangerous condition that the fine leakage develops into a large amount of leakage; in addition, valve flushing or stopping is not needed in the diagnosis process, rail pressure fluctuation cannot be caused, further deterioration of emission cannot be caused, and driving feeling cannot be affected; the leakage fault of the oil rail pressure release valve is judged by monitoring the real-time working condition parameters of the high-pressure oil pump electromagnetic valve, the fault diagnosis process is closed-loop control, fault misjudgment caused by the defects of other parts in the common rail system can be effectively avoided, and diagnosis is more comprehensive and accurate. The diagnostic strategy may include a static leak condition or no static leak condition, but the default static leak amount is stable for a static leak condition.

Referring to fig. 6, fig. 6 is a device for diagnosing a leakage fault of a rail relief valve according to an embodiment of the present application, where the device includes: the monitoring module is used for monitoring whether the engine is in a towing state, monitoring the working state of the high-pressure oil pump electromagnetic valve and reading the real-time working condition parameters of the high-pressure oil pump electromagnetic valve; the judgment module is used for comparing the real-time working condition parameters of the electromagnetic valve of the high-pressure oil pump with the set parameter threshold value and judging whether the leakage fault exists in the oil rail pressure release valve or not.

It is worth to explain, when the high-pressure oil pump solenoid valve is high-pressure oil pump oil feed solenoid valve: the monitoring module is used for monitoring whether the engine is in a dragging state or not, reading feedback current of the oil inlet electromagnetic valve of the high-pressure oil pump, and the judging module is used for comparing the feedback current with a set feedback current threshold value, if the judging module judges that the feedback current is greater than the feedback current threshold value, the leakage fault of the oil rail pressure release valve can be judged, and if the judging module judges that the feedback current is less than or equal to the feedback current threshold value, the leakage fault of the oil rail pressure release valve can be judged.

Further, when the judging module compares the feedback current with the feedback current threshold value, the method further comprises an anti-shake detection step, in anti-shake detection time, if the judging module judges that the feedback current is larger than the feedback current threshold value, the oil rail pressure release valve is judged to have a leakage fault, and if the judging module judges that the feedback current is smaller than or equal to the feedback current threshold value, the oil rail pressure release valve is judged to have no leakage fault. The anti-shake detection can eliminate the situation that the static leakage increase amount of the oil rail pressure release valve is caused by shake of the vehicle body, so that the fault misjudgment is avoided.

It is worth to be noted that, when the high-pressure oil pump electromagnetic valve is a high-pressure oil pump oil outlet electromagnetic valve:

the monitoring module is used for monitoring whether the engine is in a dragging state or not, reading a power-on time advance angle of an oil outlet electromagnetic valve of the high-pressure oil pump maintaining stable pressure, and the judging module is used for comparing the power-on time advance angle with a set power-on time advance angle threshold value.

Furthermore, when the judging module compares the power-on time advance angle with the power-on time advance angle threshold, the method further comprises an anti-shake detection step, in the anti-shake detection time, if the judging module judges that the power-on time advance angle is larger than the power-on time advance angle threshold, the oil rail pressure release valve is judged to have the leakage fault, and if the judging module judges that the power-on time advance angle is smaller than or equal to the power-on time advance angle threshold, the oil rail pressure release valve is judged not to have the leakage fault. The anti-shake detection can eliminate the situation that the static leakage increase amount of the oil rail pressure release valve is caused by shake of the vehicle body, so that the fault misjudgment is avoided.

It is worth to be noted that before the monitoring module monitors the working state of the high-pressure oil pump electromagnetic valve and reads the real-time working condition parameters of the high-pressure oil pump electromagnetic valve, the running working condition of the engine is detected to determine whether the engine is in a towing state or not, and if the engine is not in the towing state, the engine is diagnosed after the next working condition of the engine is met; and if the engine is in a back-dragging state, judging the working condition of the automobile, wherein the qualified conditions of the working condition of the automobile comprise that the accelerator is 0, the fuel injection quantity is 0, the torque is 0 and the rail pressure is stable, the working condition of the automobile is qualified, and the monitoring module starts to monitor the working state of the electromagnetic valve of the high-pressure oil pump.

It is worth mentioning that based on the diagnosis in the closed-loop control mode of the high-pressure oil pump oil inlet electromagnetic valve, whether the pressure release valve has a leakage fault is judged by monitoring the feedback current of the high-pressure oil pump oil inlet electromagnetic valve under the set condition, the diagnosis process is closed-loop control, and the misdiagnosis of the system caused by the fault of the high-pressure oil pump oil inlet electromagnetic valve or the rail pressure sensor is eliminated; based on the diagnosis in the closed-loop control mode of the oil outlet electromagnetic valve of the high-pressure oil pump, the fault is judged by monitoring the power-on advance angle of the oil outlet electromagnetic valve of the high-pressure oil pump, the diagnosis process is also closed-loop control, the misdiagnosis of the system leakage caused by the fault of the oil outlet electromagnetic valve of the high-pressure oil pump or the rail pressure sensor is eliminated, and the diagnosis accuracy is improved; the diagnosis method has wide application range, and can be suitable for fault diagnosis of various configured fuel system engines such as a high-pressure oil pump oil inlet electromagnetic valve or a high-pressure oil pump oil outlet electromagnetic valve, an oil rail electric control pressure release valve or an oil rail mechanical pressure release valve and the like; the system can diagnose and judge the slight leakage of the system, avoid the condition of large leakage and remind a driver to check and maintain in time; the diagnosis process does not need to flush a valve or stop the machine, can not cause rail pressure fluctuation, can not cause further deterioration of emission, and can not generate any influence on driving feeling.

It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.