CN111691999A - Method and device for diagnosing leakage of common rail system - Google Patents
Method and device for diagnosing leakage of common rail system Download PDFInfo
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- CN111691999A CN111691999A CN202010582410.7A CN202010582410A CN111691999A CN 111691999 A CN111691999 A CN 111691999A CN 202010582410 A CN202010582410 A CN 202010582410A CN 111691999 A CN111691999 A CN 111691999A
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- injector
- common rail
- rail system
- pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D2041/224—Diagnosis of the fuel system
- F02D2041/225—Leakage detection
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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- Combustion & Propulsion (AREA)
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- General Engineering & Computer Science (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
The embodiment of the invention discloses a method and a device for diagnosing leakage of a common rail system. The common rail system leakage diagnosis method comprises the following steps: monitoring that the engine is changed from an operating state to a stop state in a first working cycle, controlling all injectors in the common rail system to be closed, and acquiring a first reduction rate of the pressure on a high-pressure path of the common rail system; if the first descending rate is larger than a first threshold value, controlling the injectors in the common rail system to be opened one by one independently, and obtaining a second descending rate of the pressure on a high-pressure path of the common rail system when each injector is opened independently; and determining whether the injector leaks according to the difference value between the second descending speed and the first descending speed corresponding to the injector. The technical scheme provided by the embodiment of the invention can realize timely leakage finding and diagnosis on whether the injector leaks or not when the leakage degree of the common rail system is small.
Description
Technical Field
The invention relates to the technical field of engines, in particular to a method and a device for diagnosing leakage of a common rail system.
Background
The high-pressure part of the high-pressure common rail diesel engine comprises a high-pressure oil pump, an oil pipe, a high-pressure oil rail, an oil injector and the like. The high-pressure common rail system belongs to a precise component, fuel oil leakage of the high-pressure system can not only cause energy waste, but also cause starting difficulty, and the performance of an engine can be reduced after the fuel oil leakage is serious.
There are many reasons for fuel leakage, such as abrasion of moving parts due to impurities, corrosion, etc., and poor sealing performance. The situation with prior art diagnostics is often that leaks have occurred and are relatively severe. How to diagnose the leakage of the fuel system at an early stage is the key point of the current diagnosis system.
Disclosure of Invention
The embodiment of the invention provides a method and a device for diagnosing leakage of a common rail system, which are used for finding leakage in time and diagnosing whether an injector leaks or not when the leakage degree of the common rail system is small.
In a first aspect, an embodiment of the present invention provides a method for diagnosing a common rail system leakage, including:
monitoring that the engine is changed from an operating state to a stop state in a first working cycle, controlling all injectors in the common rail system to be closed, and acquiring a first reduction rate of the pressure on a high-pressure path of the common rail system;
if the first descending rate is larger than a first threshold value, controlling the injectors in the common rail system to be opened one by one independently, and obtaining a second descending rate of the pressure on a high-pressure path of the common rail system when each injector is opened independently;
and determining whether the injector leaks according to the difference value between the second descending speed and the first descending speed corresponding to the injector.
Furthermore, the number of the injectors in the common rail system is multiple, different injectors correspond to different working cycles,
controlling injectors in a common rail system to open individually one after another includes: in a working cycle corresponding to the ejector, the ejector is controlled to be opened independently when the engine is monitored to be changed from an operating state to a stop state;
determining whether the injector leaks according to a difference between the second decreasing rate corresponding to the injector and the first decreasing rate includes: if the difference between the second decreasing rate corresponding to the injector and the first decreasing rate is less than the second threshold, the injector is determined to be leaking.
Further, in a duty cycle corresponding to the injector, it is monitored that the engine is changed from an operation state to a stop, and controlling the injector to be individually opened includes: and controlling the injectors to be opened individually when the engine is monitored to be changed from the running state to the stop state and the pressure on the high-pressure path of the common rail system is monitored to be less than or equal to the pressure required by the injectors to inject the fuel in a working cycle corresponding to the injectors.
Further, the common rail system leakage diagnosis method further includes:
if the first reduction rate is smaller than or equal to a first threshold value, determining that the common rail system has no leakage;
if the difference value between the second descending speed corresponding to the ejector and the first descending speed is larger than or equal to a second threshold value, determining that the ejector does not leak;
after determining the injector leak, further comprising:
and in a working cycle after the working cycle corresponding to the injector, when the starting or running of the engine is monitored, outputting an alarm signal corresponding to the leakage of the injector.
Further, monitoring that the engine has changed from an operating state to shutdown comprises: monitoring the rotating speed of the engine to drop to zero;
obtaining a first rate of decrease of pressure on a high pressure path of a common rail system comprises: acquiring a first pressure difference of pressure on a high-pressure path of the common rail system in a first preset time period, and taking the ratio of the first pressure difference to the first preset time period as a first descending rate;
acquiring the second rate of decrease in the pressure on the high-pressure path of the common rail system when each injector is individually opened includes: and acquiring a second pressure difference of the pressure on the high-pressure path of the common rail system when each injector is opened individually in a second preset time period, and taking the ratio of the second pressure difference to the second preset time period as a second descending rate.
In a second aspect, an embodiment of the present invention further provides a common rail system leakage diagnosis device, including:
the system comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for monitoring that the engine is changed from an operation state to a stop state in a first working cycle, controlling all injectors in the common rail system to be closed and acquiring a first reduction rate of the pressure on a high-pressure path of the common rail system;
the second obtaining module is used for controlling the injectors in the common rail system to be opened independently one by one if the first reduction rate is larger than a first threshold value, and obtaining a second reduction rate of the pressure on a high-pressure path of the common rail system when each injector is opened independently;
the first determining module is used for determining whether the injector leaks according to the difference value of the second descending rate corresponding to the injector and the first descending rate.
Furthermore, the number of the injectors in the common rail system is multiple, different injectors correspond to different working cycles,
the second acquisition module is used for monitoring that the engine is changed from a running state to a stop state in a working cycle corresponding to the injector, and controlling the injector to be opened independently;
the first determination module is used for determining that the injector leaks if a difference value between a second descending rate corresponding to the injector and the first descending rate is smaller than a second threshold value.
Further, the second acquisition module is configured to control the injector to open alone when it is monitored that the engine is turned off from an operating state and a pressure on a high pressure path of the common rail system is less than or equal to a pressure required for the injector to inject fuel during a duty cycle corresponding to the injector.
The first determining module is further used for determining that the injector does not leak if the difference value between the second descending rate corresponding to the injector and the first descending rate is larger than or equal to a second threshold value;
the common rail system leakage diagnosis device further includes:
the second determining module is used for determining that the common rail system has no leakage if the first reduction rate is smaller than or equal to a first threshold value;
and the alarm module is used for outputting an alarm signal corresponding to the leakage of the injector in a working cycle after the working cycle corresponding to the injector in case of monitoring that the engine is started or operated after the first determination module determines that the injector leaks.
Further, monitoring that the engine has changed from an operating state to shutdown comprises: monitoring the rotating speed of the engine to drop to zero;
obtaining a first rate of decrease of pressure on a high pressure path of a common rail system comprises: acquiring a first pressure difference of pressure on a high-pressure path of the common rail system in a first preset time period, and taking the ratio of the first pressure difference to the first preset time period as a first descending rate;
acquiring the second rate of decrease in the pressure on the high-pressure path of the common rail system when each injector is individually opened includes: and acquiring a second pressure difference of the pressure on the high-pressure path of the common rail system when each injector is opened individually in a second preset time period, and taking the ratio of the second pressure difference to the second preset time period as a second descending rate.
According to the technical scheme of the embodiment of the invention, the engine is monitored to be changed from the running state to the shutdown state in the first working cycle, all injectors in the common rail system are controlled to be closed, and the first reduction rate of the pressure on the high-pressure path of the common rail system is obtained; if the first descending rate is larger than a first threshold value, controlling the injectors in the common rail system to be opened one by one independently, and obtaining a second descending rate of the pressure on a high-pressure path of the common rail system when each injector is opened independently; and determining whether the injector leaks according to the difference value between the second descending rate and the first descending rate corresponding to the injector, namely judging whether the injector leaks according to the variation of the descending rate of the pressure on the high-pressure path of the common rail system before and after the injector is opened independently, thereby realizing the diagnosis of whether the injector leaks.
Drawings
FIG. 1 is a flow chart of a method for diagnosing common rail system leakage according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a common rail system according to an embodiment of the present invention
FIG. 3 is a flow chart of a method for diagnosing a common rail system leakage according to an embodiment of the present invention;
FIG. 4 is a flow chart illustrating a method for diagnosing a common rail system leakage according to an embodiment of the present invention;
FIG. 5 is a schematic block diagram of an engine cylinder according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a common rail system leakage diagnosis device according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of still another common rail system leakage diagnosis device according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
The embodiment of the invention provides a method for diagnosing leakage of a common rail system. Fig. 1 is a flowchart of a common rail system leakage diagnosis method according to an embodiment of the present invention. Fig. 2 is a schematic structural diagram of a common rail system according to an embodiment of the present invention. The common rail system leakage diagnosis method may be performed by a common rail system leakage diagnosis device, which may be implemented in software and/or hardware, and may be integrated in an Electronic Control Unit (ECU) of an engine, and the like. The common rail system leakage diagnosis method specifically comprises the following steps:
in a first operating cycle, it is monitored that the engine has changed from an operating state to a stop, all injectors in the common rail system are controlled to close, and a first rate of decrease of the pressure in the high pressure path of the common rail system is obtained, step 110.
The common rail system may include a storage tank 10, a filter 20, a high pressure pump 30, a common rail 40, and an injector 50, which are sequentially communicated through pipes. The tank 10 is used for storing fuel, which may be oil or gas fuel. The filter 20 serves to filter moisture and foreign substances. High pressure pump 30 is used to power the circulating flow of fuel in the system. The fuel injector 50 is used to inject fuel into a combustion chamber of the engine. The high pressure path of the common rail system may include a high pressure pump outlet, a conduit 41 communicating between the high pressure pump outlet and the common rail conduit, and a conduit 42 communicating between the common rail conduit and the injector inlet. The low pressure path of the common rail system may include a conduit communicating between the storage tank and the filter, a conduit communicating between the filter and the high pressure pump, and a conduit communicating an oil return of the high pressure pump, an oil return of the common rail pipe, and an oil return of the injector to the storage tank.
It should be noted that each operating cycle of the engine may include a plurality of phases, such as an engine start phase, an engine run phase, and an engine stop phase. During the engine starting phase, the rotation speed of the engine is gradually increased from zero, the high-pressure pump starts to start and operates, and the pressure on the high-pressure path of the common rail system is gradually increased from zero. In the engine operation stage, the rotation speed of the engine is greater than zero, the same rotation speed can be maintained or the rotation speeds of a plurality of gears can be switched, the high-pressure pump keeps operating, the pressure on the high-pressure path of the common rail system is kept in a high-pressure state, and if the common rail system leaks to a small extent, the rotation speed of the high-pressure pump is increased so as to keep the pressure on the high-pressure path of the common rail system in the high-pressure state. During the engine stop phase (out run), the engine speed is reduced to zero, the high-pressure pump is deactivated and the pressure in the high-pressure path of the common rail system will gradually drop to zero. The work cycle may be a driving cycle of the vehicle. It should be noted that the first working cycle may be the first working cycle of the engine or other working cycles, which is not limited in the embodiment of the present invention.
Optionally, monitoring that the engine has changed from an operating state to shutdown comprises: the engine speed is monitored to drop to zero. Optionally, obtaining the first reduction rate of the pressure on the high-pressure path of the common rail system comprises: a first pressure difference of the pressure on a high-pressure path of the common rail system in a first preset time period is obtained, and the ratio of the first pressure difference to the first preset time period is used as a first descending rate. Alternatively, a pressure sensor may be provided on the common rail pipe 40 to obtain the pressure on the high pressure path of the common rail system.
And step 120, if the first descending rate is larger than a first threshold value, controlling the injectors in the common rail system to be opened one by one, and acquiring a second descending rate of the pressure on the high-pressure path of the common rail system when each injector is opened independently.
When the engine is stopped from the running state, the high-pressure pump stops working, the pressure on the high-pressure path of the common rail system gradually decreases to zero, if the common rail system does not leak, the first decreasing rate of the pressure on the high-pressure path of the common rail system is smaller, and if the common rail system leaks, the first decreasing rate of the pressure on the high-pressure path of the common rail system is larger, so that when the first decreasing rate is larger than the first threshold value, the common rail system leaks. The number of injectors in the common rail system may be one or more. If the number of the injectors in the common rail system is multiple, the injectors can be individually opened one by one when the engine is monitored to be changed from the operating state to the stop state in the same working cycle, or one part of the injectors can be individually opened one by one when the engine is monitored to be changed from the operating state to the stop state in one working cycle, and the other part of the injectors can be individually opened one by one when the engine is monitored to be changed from the operating state to the stop state in another working cycle. The number of the injectors which are individually opened one by one when the engine is monitored to be stopped from the running state in each working cycle is not limited in the embodiment of the invention. Some or all of the injectors in the common rail system may be individually opened one by one in a first working cycle. Alternatively, the obtaining a second rate of decrease in pressure on the high pressure path of the common rail system when each injector is individually opened includes: and acquiring a second pressure difference of the pressure on the high-pressure path of the common rail system when each injector is opened individually in a second preset time period, and taking the ratio of the second pressure difference to the second preset time period as a second descending rate.
Step 130, determining whether the injector leaks according to a difference between the second descent rate corresponding to the injector and the first descent rate.
Wherein if the injector does not leak, the rate of decrease in pressure in the high pressure path before and after the injector is opened will vary greatly when the injector is opened alone and the remaining injectors are closed. If the injector leaks, the rate of decrease in pressure in the high-pressure path before and after the injector opens does not change much when the injector is opened alone and the remaining injectors are closed. Whether the injector leaks or not can be determined according to the difference of the decreasing rates of the pressures on the high-pressure paths of the common rail system before and after the injector is opened independently, if the difference is smaller, the injector leaks, if the difference is larger, the injector does not leak,
for example, the number of the injectors in the common rail system is two, and the injectors are respectively a first injector and a second injector, if the first falling rate dP1 is greater than a first threshold, the first injector can be controlled to be opened alone, the second injector can be controlled to be closed, and a second falling rate dP21 of the pressure on the high-pressure path of the common rail system when the first injector is opened alone, that is, a second falling rate corresponding to the first injector, is obtained, and whether the first injector leaks or not can be determined according to the difference between the second falling rate dP21 corresponding to the first injector and the first falling rate dP 1; thereafter, it may be determined whether the second injector leaks, based on a difference between the second lowering rate dP22 corresponding to the second injector and the first lowering rate dP1, by opening the second injector alone, closing the first injector, and acquiring the second lowering rate dP22 of the pressure on the high pressure path of the common rail system when the second injector is opened alone, that is, the second lowering rate dP22 corresponding to the second injector. The first injector and the second injector may be separately opened one after the other in the first working cycle; alternatively, the first injector and the second injector may be individually opened one after the other in one working cycle after the first working cycle when the engine is changed from the running state to the stop state; alternatively, the first and second injectors may each be separately opened in a different duty cycle following the first duty cycle. Determining that the first injector does not leak if a difference between the second rate of decrease dP21 and the first rate of decrease dP1 corresponding to the first injector is greater than or equal to a fourth threshold; if the difference between the second rate of decrease dP21 and the first rate of decrease dP1 corresponding to the first injector is less than the fourth threshold, then a first injector leak is determined. Determining that the second injector does not leak if a difference between the second rate of decrease dP22 and the first rate of decrease dP1 corresponding to the second injector is greater than or equal to a fifth threshold; if the difference between the second rate of decrease dP22 and the first rate of decrease dP1 corresponding to the second injector is less than the fifth threshold, then a second injector leak is determined. The first injector and the second injector are separately opened in sequence in the same working cycle, and the pressure on the high-pressure path of the common rail system is gradually reduced in the shutdown stage, so the first injector and the second injector are not opened simultaneously, the pressure on the high-pressure path of the common rail system at the initial moment when the first injector is separately opened is different from the pressure on the high-pressure path of the common rail system at the initial moment when the second injector is separately opened, and the selected fourth threshold value and the selected fifth threshold value are different. The greater the pressure on the high pressure path of the common rail system, the greater the rate of decrease of the pressure on the high pressure path of the common rail system when either injector is opened alone.
According to the technical scheme, the engine is monitored to be changed from the running state to the stop state in the first working cycle, all injectors in the common rail system are controlled to be closed, and a first reduction rate of the pressure on a high-pressure path of the common rail system is obtained; if the first descending rate is larger than a first threshold value, controlling the injectors in the common rail system to be opened one by one independently, and obtaining a second descending rate of the pressure on a high-pressure path of the common rail system when each injector is opened independently; and determining whether the injector leaks according to the difference value between the second descending rate and the first descending rate corresponding to the injector, namely judging whether the injector leaks according to the variation of the descending rate of the pressure on the high-pressure path of the common rail system before and after the injector is opened independently, thereby realizing the diagnosis of whether the injector leaks.
The embodiment of the invention provides a method for diagnosing leakage of a common rail system. Fig. 3 is a flowchart of a method for diagnosing a leakage of a common rail system according to an embodiment of the present invention. On the basis of the above embodiment, the number of injectors in the common rail system is plural, and different injectors are individually opened in different working cycles, and the method includes:
step 210, monitoring that the engine is changed from an operating state to a stop in a first working cycle, controlling all injectors in the common rail system to close, and acquiring a first reduction rate of the pressure on the high-pressure path of the common rail system.
And step 220, if the first reduction rate is larger than a first threshold value, in a working cycle corresponding to the injector, monitoring that the engine is changed from a running state to a stop state, controlling the injector to be opened independently, and obtaining a second reduction rate of the pressure on a high-pressure path of the common rail system when each injector is opened independently, wherein the number of the injectors in the common rail system is multiple, and different injectors correspond to different working cycles.
Wherein the duty cycle corresponding to the first individually opened injector may be the first duty cycle, or the duty cycle corresponding to the first individually opened injector may be a duty cycle after the first duty cycle.
Illustratively, the number of the injectors in the common rail system is two, that is, a first injector and a second injector, respectively, and if the first falling rate dP1 is greater than the first threshold value, in one operation cycle after the first operation cycle, for example, the second operation cycle may be performed, when the engine is changed from the operating state to the stop, the first injector is individually opened, the second injector is closed, and the second falling rate dP21 of the pressure on the high-pressure path of the common rail system when the first injector is individually opened is obtained; in another operation cycle after the first operation cycle, which may be, for example, the third operation cycle, when the engine is changed from the operating state to the stop, the second injector is opened alone, the first injector is closed, and the second rate dP22 of decrease in the pressure on the high-pressure path of the common rail system when the second injector is opened alone is acquired. And in a working cycle corresponding to the injectors, when the engine is monitored to be changed from the running state to the stop state and the pressure on the high-pressure path of the common rail system is monitored to be equal to the preset pressure, the injectors are controlled to be opened independently, so that the pressure on the high-pressure path of the common rail system is the same at the initial moment when all the injectors are opened independently.
Step 230, if the difference between the second decreasing rate corresponding to the injector and the first decreasing rate is less than the second threshold, determining that the injector is leaking.
Here, if the pressure on the high-pressure path of the common rail system at the initial time when all the injectors are individually opened is the same, the threshold value of the leakage judgment of all the injectors may be the same. For example, if the difference between the second rate of decrease dP21 and the first rate of decrease dP1 corresponding to the first injector is greater than or equal to the second threshold, then it is determined that the first injector is not leaking; if the difference between the second rate of decrease dP21 and the first rate of decrease dP1 corresponding to the first injector is less than the second threshold, then a first injector leak is determined. Determining that the second injector does not leak if a difference between the second rate of decrease dP22 and the first rate of decrease dP1 corresponding to the second injector is greater than or equal to a second threshold; if the difference between the second rate of decrease dP22 and the first rate of decrease dP1 corresponding to the second injector is less than the second threshold, then a second injector leak is determined.
The embodiment of the invention provides a method for diagnosing leakage of a common rail system. Fig. 4 is a flowchart of a method for diagnosing a leakage of a common rail system according to an embodiment of the present invention. On the basis of the above embodiment, the method includes:
in a first operating cycle, it is monitored that the engine has changed from an operating state to a stop, all injectors in the common rail system are controlled to close, and a first rate of decrease of pressure in the high pressure path of the common rail system is obtained, step 310.
And 320, if the first reduction rate is larger than a first threshold value, in a working cycle corresponding to the injector, when the engine is monitored to be stopped from the running state and the pressure on the high-pressure path of the common rail system is monitored to be smaller than or equal to the pressure required by the injector to inject the fuel, controlling the injector to be independently opened, and acquiring a second reduction rate of the pressure on the high-pressure path of the common rail system when each injector is independently opened, wherein the number of the injectors in the common rail system is multiple, and different injectors correspond to different working cycles.
When the pressure on the high-pressure path of the common rail system is monitored to be smaller than or equal to the pressure required by the injector to inject the fuel, the injector is controlled to be independently opened, the injector cannot inject the fuel to a cylinder of the engine, and therefore the situation that the fuel enters the cylinder of the engine and finally enters an oil pan of the engine to easily dilute the engine oil can be avoided.
Fig. 5 is a schematic structural diagram of an engine cylinder according to an embodiment of the present invention, in an engine operation stage, an injector 50 is opened and injects fuel into a combustion chamber 6 of the engine to perform combustion, generate gas, and discharge the gas from an exhaust port. If the pressure in the high-pressure path of the common rail system is higher than the pressure required by the injector to inject the fuel during the engine stop phase, the injector 50 is controlled to be opened alone, and the injector 50 injects the fuel into the combustion chamber 6 of the cylinder of the engine, but the fuel is not ignited, so that the fuel enters the oil pan 1 of the engine along the edge of the piston 4, and the oil 4 is easily diluted. The engine oil 4 is used as lubricating oil of a lubricating system (not shown in the figure) of the engine and is relatively viscous; and the fuel is leaner. The engine oil 4 is combusted in the combustion chamber 6, and the hot gas is expanded to push the piston 4 to move. The piston 5 is connected to the crankshaft 2 via a connecting rod 3, and the reciprocating motion of the piston 5 is converted into the rotational motion of the crankshaft 2.
Step 330, if the difference between the second decreasing rate corresponding to the injector and the first decreasing rate is less than the second threshold, determining that the injector is leaking.
And 340, in a working cycle after the working cycle corresponding to the injector, when the starting or the running of the engine is monitored, outputting an alarm signal corresponding to the leakage of the injector.
Wherein, the alarm signal can comprise an audio alarm signal, a light alarm signal and the like. In the working cycle after the working cycle corresponding to the ejector, when the starting or the running of the engine is monitored, the alarm signal corresponding to the leakage of the ejector is output, so that the condition that the alarm device stops working in the stop stage in the working cycle corresponding to the ejector can be avoided.
And step 350, if the difference value between the second descending speed corresponding to the injector and the first descending speed is larger than or equal to a second threshold value, determining that the injector does not leak.
If the first reduction rate is greater than the first threshold value and all the injectors are not leaked, it is determined that the high-pressure pump plunger 31 or the high-pressure connecting pipe and the like are leaked, and an alarm signal corresponding to the leakage of the high-pressure pump plunger or the high-pressure connecting pipe can be output in a working cycle after the working cycle corresponding to the last injector which is opened independently, so as to remind a driver of checking.
And step 360, if the first reduction rate is smaller than or equal to the first threshold value, determining that the common rail system has no leakage.
If it is determined that the common rail system has no leakage, the operation cycle after the first operation cycle may be regarded as the first operation cycle again, and the process returns to step 310.
The embodiment of the invention provides a device for diagnosing leakage of a common rail system. Fig. 6 is a schematic structural diagram of a common rail system leakage diagnosis device according to an embodiment of the present invention. The common rail system leakage diagnosis device can be used for executing the common rail system leakage diagnosis method provided by any embodiment of the invention. The common rail system leakage diagnosis device comprises: a first acquisition module 410, a second acquisition module 420, and a first determination module 430.
The first obtaining module 410 is used for monitoring that the engine is changed from an operation state to a stop state in a first working cycle, controlling all injectors in the common rail system to be closed, and obtaining a first reduction rate of the pressure on a high-pressure path of the common rail system; the second obtaining module 420 is configured to control the injectors in the common rail system to be individually opened one by one if the first decreasing rate is greater than a first threshold, and obtain a second decreasing rate of the pressure on the high-pressure path of the common rail system when each injector is individually opened; the first determination module 430 is configured to determine whether an injector is leaking based on a difference between a second rate of descent corresponding to the injector and a first rate of descent.
The common rail system leakage diagnosis device provided by the embodiment of the present invention may be used to execute the common rail system leakage diagnosis method provided by any embodiment of the present invention, and therefore the common rail system leakage diagnosis device provided by the embodiment of the present invention also has the beneficial effects described in the above embodiments, and details are not described here.
Optionally, the number of the injectors in the common rail system is multiple, different injectors correspond to different working cycles, and the second obtaining module 420 is configured to detect that the engine is turned off from the operating state in the working cycle corresponding to the injector, and control the injector to be opened alone.
Optionally, the first determination module 430 is configured to determine that the injector is leaking if a difference between a second rate of descent corresponding to the injector and the first rate of descent is less than a second threshold.
Optionally, the second obtaining module 420 is configured to control the injector to open alone when the engine is monitored to be turned off from the operating state and the pressure in the high pressure path of the common rail system is monitored to be less than or equal to a pressure required for the injector to inject the fuel during a working cycle corresponding to the injector.
Optionally, the first determination module 430 is further configured to determine that the injector does not leak if the difference between the second decreasing rate corresponding to the injector and the first decreasing rate is greater than or equal to a second threshold.
Optionally, on the basis of the foregoing embodiment, fig. 7 is a schematic structural diagram of another common rail system leakage diagnosis device provided in an embodiment of the present invention, where the common rail system leakage diagnosis device further includes: the second determination module 440 is configured to determine that the common rail system is leak free if the first drop rate is less than or equal to a first threshold.
Alternatively, with continuing reference to fig. 7 on the basis of the above-described embodiment, the common rail system leakage diagnosis device further includes: and an alarm module 450 for outputting an alarm signal corresponding to the leakage of the injector in a working cycle after the working cycle corresponding to the injector after the first determination module 430 determines that the injector leaks and when the engine is monitored to be started or operated.
Optionally, monitoring that the engine has changed from an operating state to shutdown comprises: the engine speed is monitored to drop to zero.
Optionally, obtaining the first reduction rate of the pressure on the high-pressure path of the common rail system comprises: a first pressure difference of the pressure on a high-pressure path of the common rail system in a first preset time period is obtained, and the ratio of the first pressure difference to the first preset time period is used as a first descending rate.
Alternatively, the obtaining a second rate of decrease in pressure on the high pressure path of the common rail system when each injector is individually opened includes: and acquiring a second pressure difference of the pressure on the high-pressure path of the common rail system when each injector is opened individually in a second preset time period, and taking the ratio of the second pressure difference to the second preset time period as a second descending rate.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A method for diagnosing a common rail system leakage, comprising:
monitoring that an engine is changed from an operating state to a stop state in a first working cycle, controlling all injectors in the common rail system to be closed, and acquiring a first reduction rate of pressure on a high-pressure path of the common rail system;
if the first descending rate is larger than a first threshold value, controlling the injectors in the common rail system to be opened one by one and obtaining a second descending rate of the pressure on the high-pressure path of the common rail system when each injector is opened independently;
determining whether the injector leaks based on a difference between a second rate of descent corresponding to the injector and the first rate of descent.
2. The method of claim 1, wherein the common rail system includes a plurality of injectors, each injector corresponding to a different operating cycle,
controlling injectors in the common rail system to open individually one by one includes: in a working cycle corresponding to an injector, monitoring that the engine is changed from an operating state to a stop state, and controlling the injector to be opened independently;
determining whether the injector leaks based on a difference between a second rate of descent corresponding to the injector and the first rate of descent includes: if the difference between the second rate of descent corresponding to the injector and the first rate of descent is less than a second threshold, determining that the injector is leaking.
3. The common rail system leakage diagnostic method as set forth in claim 2, wherein, in a duty cycle corresponding to an injector, it is monitored that the engine changes from an operating state to a stop, and controlling the injector to open alone comprises: and controlling the injector to be opened alone when the engine is monitored to be stopped from the running state and the pressure on the high-pressure path of the common rail system is monitored to be less than or equal to the pressure required by the injector to inject the fuel in a working cycle corresponding to the injector.
4. The method of diagnosing a leak in a common rail system according to claim 2, further comprising:
if the first reduction rate is less than or equal to a first threshold, determining that the common rail system has no leakage;
if the difference value between the second descending rate corresponding to the injector and the first descending rate is larger than or equal to a second threshold value, determining that the injector does not leak;
after determining the injector leak, further comprising:
and in a working cycle after the working cycle corresponding to the injector, when the starting or the running of the engine is monitored, outputting an alarm signal corresponding to the leakage of the injector.
5. The common rail system leakage diagnosis method according to claim 1,
monitoring that the engine has changed from an operating state to shutdown includes: monitoring a drop in the engine speed to zero;
obtaining a first rate of decrease of pressure on a high pressure path of the common rail system comprises: acquiring a first pressure difference of pressure on a high-pressure path of the common rail system in a first preset time period, and taking the ratio of the first pressure difference to the first preset time period as a first descending rate;
acquiring a second rate of decrease in pressure on a high pressure path of the common rail system when each injector is individually opened includes: and acquiring a second pressure difference of the pressure on the high-pressure path of the common rail system when each injector is opened individually within a second preset time period, and taking the ratio of the second pressure difference to the second preset time period as a second descending rate.
6. A common rail system leakage diagnosis device, comprising:
the system comprises a first obtaining module, a second obtaining module and a control module, wherein the first obtaining module is used for monitoring that an engine is changed from an operation state to a stop state in a first working cycle, controlling all injectors in the common rail system to be closed, and obtaining a first reduction rate of pressure on a high-pressure path of the common rail system;
the second obtaining module is used for controlling the injectors in the common rail system to be opened independently one by one if the first descending rate is larger than a first threshold value, and obtaining a second descending rate of the pressure on a high-pressure path of the common rail system when each injector is opened independently;
the first determining module is used for determining whether the injector leaks according to the difference value of a second descending rate corresponding to the injector and the first descending rate.
7. The common rail system leakage diagnostic device of claim 6, wherein there are a plurality of injectors in said common rail system, each injector corresponding to a different operating cycle,
the second acquisition module is used for monitoring that the engine is changed from an operating state to a stop state in a working cycle corresponding to an injector, and controlling the injector to be opened independently;
the first determining module is used for determining that the injector leaks if the difference value between a second descending rate corresponding to the injector and the first descending rate is smaller than a second threshold value.
8. The common rail system leakage diagnostic apparatus as claimed in claim 7, wherein the second acquisition module is configured to control the injector to be opened alone when it is monitored that the engine is changed from an operating state to a stop and a pressure on a high pressure path of the common rail system is less than or equal to a pressure required for the injector to inject the fuel in a working cycle corresponding to the injector.
9. The common rail system leakage diagnostic apparatus of claim 7, wherein the first determining module is further configured to determine that an injector does not leak if a difference between a second rate of decrease corresponding to the injector and the first rate of decrease is greater than or equal to a second threshold;
the common rail system leakage diagnosis device further includes:
the second determining module is used for determining that the common rail system has no leakage if the first descending speed is smaller than or equal to a first threshold value;
and the alarm module is used for outputting an alarm signal corresponding to the leakage of the injector in a working cycle after the working cycle corresponding to the injector after the first determination module determines that the injector leaks and when the engine is monitored to be started or operated.
10. The common rail system leakage diagnosis device according to claim 7,
monitoring that the engine has changed from an operating state to shutdown includes: monitoring a drop in the engine speed to zero;
obtaining a first rate of decrease of pressure on a high pressure path of the common rail system comprises: acquiring a first pressure difference of pressure on a high-pressure path of the common rail system in a first preset time period, and taking the ratio of the first pressure difference to the first preset time period as a first descending rate;
acquiring a second rate of decrease in pressure on a high pressure path of the common rail system when each injector is individually opened includes: and acquiring a second pressure difference of the pressure on the high-pressure path of the common rail system when each injector is opened individually within a second preset time period, and taking the ratio of the second pressure difference to the second preset time period as a second descending rate.
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