A method for judging fuel leakage of electronically controlled high-pressure common rail engine

Abstract

The present application discloses a method for judging fuel leakage of an electronically controlled high-pressure common rail engine, wherein a return oil temperature sensor is added to the return oil main pipe of the engine fuel supply system to monitor the return oil temperature; the engine is started and adjusted to an intermediate operating condition; the engine maintains stable operation in the intermediate operating condition, at which time the oil inlet temperature remains stable, and the change trend of the return oil temperature is monitored; after a period of stable operation, if the return oil temperature is stable in a certain temperature range, it is considered that there is no leakage in the fuel system; if the return oil temperature continues to rise and exceeds a pre-set threshold, a fuel leakage fault alarm is issued. The present invention utilizes the working characteristics of the electronically controlled common rail engine itself, adds a temperature sensor to the return oil main pipe, monitors the return oil temperature, and can quickly judge whether there is leakage in the high-pressure pipeline of the fuel system at low speed and low load, thereby reducing the engine damage caused by the sudden shutdown of the engine at high speed and high load due to fuel leakage.

Description

Technical Field

[0001] The present application relates to a method for judging fuel leakage of an electronically controlled high-pressure common rail engine, and belongs to the technical field of judging fuel leakage of an engine. Background Art

[0002] In the prior art, the fuel supply system of the electronically controlled high-pressure common rail engine is composed of a fuel pump, a high-pressure oil pump, a high-pressure common rail pipe, an injector, and corresponding connecting pipes between these main components. Since there are many components involved, and there are high-pressure oil inlet system and low-pressure oil return system. Affected by the quality of the components themselves, assembly quality, design defects, etc., it is easy for the hydraulic pipeline to leak in practice. When there is a slight leakage in the hydraulic system, it will not affect the use of the engine. When there is a certain amount of fuel leakage in the hydraulic system, when the engine is under light load, the high-pressure common rail system can still maintain normal operation. However, when the engine is under heavy load, the engine high-pressure common rail system will not work properly, the engine speed will drop rapidly, and the engine will suddenly stop due to crushing, which will cause great damage to the engine running at high speed and heavy load. Summary of the invention

[0003] The technical problem to be solved by the present application is how to determine whether there is a fuel leak in the high-pressure fuel system.

[0004] In order to solve the above technical problems, the technical solution of the present application is to provide a method for judging fuel leakage of an electronically controlled high-pressure common rail engine, wherein a return oil temperature sensor is added to the return oil main pipe of the engine fuel supply system to monitor the return oil temperature;

[0005] Start the engine and adjust the engine to the intermediate operating condition;

[0006] The engine maintains stable operation in the intermediate working condition, at which time the oil inlet temperature remains stable, and the change trend of the oil return temperature is monitored;

[0007] After a period of stable operation, if the return oil temperature is stable within a certain temperature range, it is considered that there is no leakage in the fuel system; if the return oil temperature continues to rise and exceeds the pre-set threshold, a fuel leakage fault alarm is issued.

[0008] Preferably, the intermediate operating condition refers to increasing the engine speed to a stable speed, which is less than or equal to the rated speed; and gradually increasing a small load, which is less than the rated load.

[0009] Preferably, when a fuel leakage fault alarm is issued, whether a serious leakage has occurred is determined based on the return oil temperature rise rate: the return oil temperature rise rate is calculated, and when the monitored oil temperature rise rate exceeds the set threshold, a serious fuel leakage fault alarm is issued, otherwise, a general fuel leakage fault alarm is issued.

[0010] Specifically, the fuel supply system includes a fuel tank. The fuel tank passes through a fuel coarse filter, a fuel pump and a fuel fine filter and then enters a high-pressure fuel pump. The high-pressure fuel pump pressurizes the low-pressure fuel and supplies it to a high-pressure common rail. The high-pressure common rail transmits the fuel to the injector through a high-pressure fuel pipe and a connecting pipe. The excess fuel is collected in an oil return main pipe through an oil return channel and an oil return pipe and then returns to the oil return tank.

[0011] The beneficial effects of the present invention are as follows: the present invention utilizes the working characteristics of the electronically controlled common rail engine itself, separates the return oil of the fuel, adds a temperature sensor in the return oil main pipe, monitors the return oil temperature, and can quickly determine whether there is a leak in the high-pressure pipeline of the fuel system at low speed and low load, thereby reducing engine damage caused by sudden shutdown of the engine at high speed and high load due to fuel leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the fuel supply system structure with an additional oil return temperature sensor;

[0013] Figure 2 The figure is a flow chart of the method for judging fuel leakage. DETAILED DESCRIPTION

[0014] In order to make the present application more clear and understandable, a preferred embodiment is described in detail as follows with reference to the accompanying drawings.

[0015] This embodiment provides a method for quickly judging fuel leakage in an electronically controlled high-pressure common rail engine, which relies on a fuel supply system with an added oil return temperature sensor. Figure 1 As shown, the fuel enters the high-pressure fuel pump 5 from the fuel tank 1 through the fuel coarse filter 2, the fuel pump 3 and the fuel fine filter 4. The high-pressure fuel pump 5 is responsible for pressurizing the low-pressure fuel and providing it to the high-pressure common rail 6, which is then transferred to the injector 9 through the high-pressure fuel pipe 7 and the connecting pipe 8. The excess fuel is collected in the return oil main pipe through the return oil channel and the return oil pipe, and then returned to the return oil tank 10. The return oil temperature sensor 11 is connected to the return oil main pipe to monitor the return oil temperature.

[0016] The return oil tank and the oil tank are set as independent oil tanks to avoid the influence of the return oil temperature on the incoming oil.

[0017] For a fuel supply system equipped with an oil inlet constant temperature control device, the return oil can be directly introduced into the fuel tank without the need to set up a separate return oil tank.

[0018] See also Figure 2 The steps for judging fuel leakage are as follows:

[0019] Start the engine and adjust it to the intermediate working condition: specifically, increase the engine speed to a stable speed (the speed is less than or equal to the rated speed), and gradually increase a small load (the load is less than the rated load);

[0020] The engine maintains stable operation in the intermediate working condition. At this time, the oil inlet temperature remains stable. The change trend of the oil return temperature is monitored. Under normal circumstances, when the oil inlet temperature is constant, the oil return temperature is maintained in a temperature range slightly higher than the oil inlet temperature and will not rise rapidly. After a period of stable operation, if the oil return temperature is stable in a certain temperature range, it is considered that there is no leakage in the fuel system. If the oil return temperature continues to rise and exceeds the preset threshold, a fuel leakage fault alarm is issued.

[0021] Furthermore, when a fuel leakage fault alarm is issued, it can be determined whether a serious leakage has occurred based on the return oil temperature rise rate: the return oil temperature rise rate is calculated, and when the monitored oil temperature rise rate exceeds the set threshold, a serious fuel leakage fault alarm is issued, otherwise, a general fuel leakage fault alarm is issued.

[0022] This application utilizes the characteristics of the original high-pressure common rail, that is, the high-pressure oil pump in the high-pressure common rail system is responsible for pressurizing the low-pressure fuel and providing it to the high-pressure common rail, which is then transferred to the injector through the high-pressure oil pipe and the connecting pipe. When there is a fuel leak in the high-pressure fuel part, in order to maintain the rail pressure set by the electronic control unit, the high-pressure oil pump needs to continuously pump the additional pressurized fuel into the high-pressure common rail to maintain the required rail pressure. These additional high-pressure and high-temperature fuels directly enter the low-pressure return oil system from the leakage point at the connection of the high-pressure fuel pipeline. In this way, after a short period of operation, the return oil temperature of the fuel will rise rapidly. Using this principle, monitoring the change trend of the return oil temperature in the fuel system will quickly determine whether there is a fuel leak in the fuel system.

[0023] By applying the above-mentioned rapid fuel leakage judgment method, it is possible to quickly judge whether there is a fuel leakage problem in the high-pressure fuel system during the first test run of a new electronic common rail engine or after replacing the fuel high-pressure parts, thereby helping to quickly find the cause of the leakage and reduce engine failures caused by fuel leakage.

[0024] The above-described embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A method for determining fuel leakage in an electronically controlled high-pressure common rail engine, characterized in that: An oil return temperature sensor is added to the oil return main pipe of the engine fuel supply system to monitor the oil return temperature; Start the engine and adjust it to an intermediate operating condition; the intermediate operating condition means that the engine speed is increased to a stable speed, which is less than or equal to the rated speed; gradually increase a small load, which is less than the rated load; the engine maintains stable operation in the intermediate operating condition, at which time the oil inlet temperature remains stable, and the change trend of the return oil temperature is monitored; After a period of stable operation, if the return oil temperature is stable within a certain temperature range, it is considered that there is no leakage in the fuel system; if the return oil temperature continues to rise and exceeds the pre-set threshold, a fuel leakage fault alarm is issued; when a fuel leakage fault alarm is issued, it is determined whether a serious leakage has occurred based on the return oil temperature rising rate: the return oil temperature rising rate is calculated, and when the monitored oil temperature rising rate exceeds the set threshold, a serious fuel leakage fault alarm is issued, otherwise, a general fuel leakage fault alarm is issued.

2. A method for determining fuel leakage of an electronically controlled high-pressure common rail engine as claimed in claim 1, characterized in that: The fuel supply system includes a fuel tank. The fuel tank passes through a fuel coarse filter, a fuel pump and a fuel fine filter and then enters a high-pressure fuel pump. The high-pressure fuel pump pressurizes the low-pressure fuel and supplies it to a high-pressure common rail. The high-pressure common rail transmits the fuel to the injector through a high-pressure fuel pipe and a connecting pipe. Excess fuel is collected in an oil return main pipe through an oil return channel and an oil return pipe and then returns to the oil return tank.

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