CN113107694B - A rail pressure sensor fault handling method and common rail system - Google Patents

Abstract

The invention discloses a rail pressure sensor fault processing method and a common rail system, and relates to the technical field of engines. The method comprises the following steps: s1, determining that a rail pressure sensor is in a fault state, and estimating a virtual rail pressure value by a virtual sensor according to a rail pressure actual value before the rail pressure sensor fails; s2, the virtual sensor transmits the estimated virtual rail pressure value to an input module, and the input module forms a rail pressure control signal according to the virtual rail pressure value and a rail pressure set value and sends the rail pressure control signal to a PID controller; s3, after receiving the rail pressure control signal, the PID controller calculates the control duty ratio of the oil quantity metering unit to control the common rail system; and S4, the virtual sensor estimates the next virtual rail pressure value according to the virtual rail pressure value, and then the steps S2 to S4 are repeatedly executed. The method can ensure that closed-loop control can be still realized under the condition that the rail pressure sensor fails through the virtual sensor, solves the problem of rail pressure control when the rail pressure sensor is damaged, and prolongs the service life of the common rail system.

Description

A rail pressure sensor fault handling method and common rail system

technical field

The invention relates to the technical field of engines, in particular to a rail pressure sensor fault handling method and a common rail system.

Background technique

The high pressure common rail system is an oil supply system for diesel engines. In the closed-loop system composed of high-pressure oil pump, real-time pressure sensor and electronic control unit, the system can completely separate the generation of injection pressure and the injection process from each other. It uses a high-pressure oil pump to deliver high-pressure fuel to the common rail pipe, and uses a real-time pressure sensor to measure the pressure in the common rail pipe to achieve precise control, so that the pressure in the common rail pipe has nothing to do with the engine speed, thereby greatly reducing the diesel engine. The degree to which the pressure in the common rail varies with the engine speed. The electronic control unit controls the fuel injection volume of the injector, and the fuel injection volume depends on the pressure of the common rail pipe and the opening time of the solenoid valve. Usually, the pressure in the common rail pipe is called the common rail pressure, or simply called the rail pressure. In the common rail system, the common rail pressure not only determines the level of fuel injection pressure, but also is an important parameter of fuel injection metering. Its stability and transition response directly affect the performance of engine starting, idling and acceleration, so ensure accurate rail alignment It is of great significance to sample, filter and control the pressure signal. At present, most rail pressure sensors are used to monitor the rail pressure signal, but when the rail pressure sensor is damaged or the signal is unreliable due to strong electromagnetic interference, it will have a great impact on the normal operation of the system. In the current existing technology, when the rail pressure sensor fails or the strong electromagnetic interference signal is unreliable, the closed-loop control is switched to open-loop control, and the pressure relief valve of the common rail system is opened under the condition of maximum oil supply to ensure rail pressure. remain unchanged at a fixed value. However, frequent opening of the pressure relief valve will reduce the life of the common rail system. At the same time, the rail pressure will remain basically unchanged after the pressure relief valve is opened, which will deteriorate the emission and economy.

Contents of the invention

The purpose of the present invention is to provide a rail pressure sensor fault handling method and a common rail system, which can solve the problem of rail pressure control when the rail pressure sensor is damaged or is unreliable when the strong electromagnetic interference signal is received, and ensures the normal operation of the common rail system. system lifespan.

For reaching this purpose, the present invention adopts following technical scheme:

A method for troubleshooting a rail pressure sensor, comprising the following steps:

S1. Determine that the rail pressure sensor is in a fault state, and the virtual sensor estimates the virtual rail pressure value according to the actual value of the rail pressure before the rail pressure sensor fails;

S2. The virtual sensor transmits the estimated virtual rail pressure value to an input module, and the input module forms a rail pressure control signal according to the virtual rail pressure value and a rail pressure set value and sends it to a PID controller;

S3. After receiving the rail pressure control signal, the PID controller calculates the control duty ratio of the oil metering unit to control the common rail system;

S4. The virtual sensor estimates the next virtual rail pressure value according to the virtual rail pressure value, and then repeatedly executes steps S2-S4.

Optionally, step S1 specifically includes: judging whether the rail pressure sensor is in a fault state, and if so, the virtual sensor estimates the virtual rail pressure value according to the actual value of the rail pressure before the rail pressure sensor fails And execute step S2; if not, execute step S11 and then repeatedly execute step S11 and step S3.

S11. The common rail system sends the actual value of the rail pressure to the input module, and the input module forms the rail pressure control signal according to the actual value of the rail pressure and the set value of the rail pressure and sends it to The PID controller; then execute step S3 and then repeat step S11 and step S3.

Optionally, when step S11 is executed, the actual value of the rail pressure continues to initialize the virtual sensor, and when it is judged that the rail pressure sensor is in a fault state, the initialization is stopped.

Optionally, the rail pressure control signal in step S11 is equal to the rail pressure set value minus the rail pressure actual value.

Optionally, in step S4, the virtual sensor can receive the control duty ratio of the fuel metering unit and the virtual rail pressure value output by the common rail system, combined with the engine speed and the power-on time of the fuel injector Estimate the next virtual rail pressure value.

Optionally, the virtual sensor estimates the virtual rail pressure value through the formula P ₁ ′=β(Q ₁ −Q ₂ )/V;

Among them: P ₁ 'is the first derivative of the virtual rail pressure; β is the elastic modulus of fuel; Q ₁ is the average fuel delivery volume of the high-pressure fuel pump; Q ₂ is the average fuel injection volume of the injector; V is the volume of the common rail pipe.

Optionally, said Q ₁ =-k ₁ D+b;

Among them: D is the control duty ratio of the fuel quantity metering unit; K ₁ is a constant; b is a constant.

Optionally, said Q ₂ =k ₂ TnP;

Among them: k ₂ is a constant; n is the engine speed; T is the power-on time of the fuel injector; P is the last virtual rail pressure value.

Optionally, the rail pressure control signal in step S2 is equal to the rail pressure set value minus the virtual rail pressure value.

A common rail system includes a rail pressure sensor. When the rail pressure sensor fails, the common rail system uses the above-mentioned rail pressure sensor fault handling method to perform rail pressure control.

Beneficial effects of the present invention: the rail pressure sensor fault processing method provided by the present invention first determines that the rail pressure sensor is in a fault state, and the virtual sensor estimates the virtual rail pressure value according to the actual value of the rail pressure before the rail pressure sensor fails; then the virtual sensor will The estimated virtual rail pressure value is sent to the input module, and the input module forms a rail pressure control signal based on the virtual rail pressure value and the rail pressure set value and sends it to the PID controller; then the PID controller calculates the oil pressure after receiving the rail pressure control signal The metering unit controls the duty ratio to control the common rail system; finally, the virtual sensor estimates the next virtual rail pressure value according to the virtual rail pressure value, and then repeats steps S2-S4. Through the virtual sensor, this processing method can ensure that closed-loop control can still be realized in the case of rail pressure sensor failure, solves the problem of rail pressure control when the rail pressure sensor is damaged or is unreliable due to strong electromagnetic interference signals, and prolongs the life of the common rail system. service life.

The common rail system provided by the invention includes a rail pressure sensor. When the rail pressure sensor fails, the common rail system can continue to work, prolonging the service life of the system.

Description of drawings

Fig. 1 is a flow chart of main steps of a rail pressure sensor fault handling method provided by an embodiment of the present invention;

Fig. 2 is a detailed step-by-step flowchart of a rail pressure sensor fault handling method provided by an embodiment of the present invention;

Fig. 3 is a control flowchart of a rail pressure sensor fault handling method provided by an embodiment of the present invention.

In the picture:

1-virtual sensor; 2-input module; 3-PID controller; 4-common rail system.

detailed description

In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only the technical solutions of the present invention. Some, but not all, embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected" and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated ; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

In the present invention, unless otherwise clearly specified and limited, a first feature being "on" or "under" a second feature may include direct contact between the first and second features, and may also include the first and second features Not in direct contact but through another characteristic contact between them. Moreover, "above", "above" and "above" the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "under" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

As shown in Figures 1 and 3, the rail pressure sensor fault handling method mainly includes the following steps:

S1. Determine that the rail pressure sensor is in a fault state, and the virtual sensor 1 estimates the virtual rail pressure value according to the actual value of the rail pressure before the rail pressure sensor fails;

S2. The virtual sensor 1 sends the estimated virtual rail pressure value to the input module 2, and the input module 2 forms a rail pressure control signal according to the virtual rail pressure value and the rail pressure set value input by the input module 2 and sends it to the PID controller 3;

S3. After receiving the rail pressure control signal, the PID controller 3 calculates the fuel quantity metering unit to control the duty ratio to control the common rail system 4;

S4. The virtual sensor 1 estimates the next virtual rail pressure value according to the virtual rail pressure value, and then repeats steps S2-S4.

It can be understood that the rail pressure sensor failure processing method can ensure that the closed-loop control can still be realized in the case of a rail pressure sensor failure through the virtual sensor 1, and solves the problem that the rail pressure sensor is damaged or is unreliable when a strong electromagnetic interference signal is received. Pressure control problem, prolonging the service life of the common rail system 4.

In this embodiment, the oil quantity metering unit is the inlet throttle valve of the high-pressure oil pump, and its duty ratio can control the opening of the inlet throttle valve, so as to control the amount of oil entering the common rail pipe of the common rail system 4, Thereby adjusting the size of the rail pressure. As for the specific control process and principle, they are already in the prior art, and will not be repeated here. The PID controller 3 adopts PID control, including a proportional link, an integral link and a differential link, and constructs a system closed-loop control. As for the specific structure and control principle of the PID controller 3, they are already in the prior art, and will not be repeated here.

As shown in Figures 2 and 3, the rail pressure sensor fault handling method specifically includes the following steps:

S1. Determine whether the rail pressure sensor is in a fault state, if so, virtual sensor 1 estimates the virtual rail pressure value according to the actual value of the rail pressure before the rail pressure sensor fails, and executes step S2; if not, executes step S11;

S11. The common rail system 4 sends the actual value of the rail pressure to the input module 2, and the input module 2 forms a rail pressure control signal according to the actual value of the rail pressure and the set value of the rail pressure and sends it to the PID controller 3; then execute step S3 and repeat Execute step S11 and step S3.

It can be understood that when the rail pressure sensor is in a normal state, the common rail system 4 sends the actual value of the rail pressure measured by the rail pressure sensor to the input module 2, and the input module 2 passes the input rail pressure set value and the actual rail pressure The value forms a rail pressure control signal to control the PID controller 3, that is, the virtual rail pressure value estimated by the virtual sensor 1 is not used at this time. Specifically, the rail pressure control signal in step S11 is equal to the set value of the rail pressure minus the actual value of the rail pressure. As for the specific structure and principle of the input module 2, it is already in the prior art. At the same time, how to judge whether the rail pressure sensor fails is already in the prior art, and will not be repeated here. In this embodiment, when the rail pressure sensor does not fail, the actual value of the rail pressure measured by the rail pressure sensor to control the PID controller 3 to further control the common rail system 4 is also a closed-loop control.

Optionally, when step S11 is executed, the virtual sensor 1 is continuously initialized by the actual value of the rail pressure, and the initialization is stopped when it is judged that the rail pressure sensor is in a failure state. It can be understood that when the rail pressure sensor is working normally, although the virtual rail pressure value estimated by the virtual sensor 1 is not used at this time, before the rail pressure sensor fails, the rail pressure sensor output in the common rail system 4 is continuously used The actual value of the rail pressure initializes the actual value of the rail pressure used by the virtual sensor 1 to estimate, and stops the initialization after a fault occurs, which can ensure the accuracy of the estimation of the virtual rail pressure value by the virtual sensor 1, so it can improve the effect of rail pressure control in the fault mode .

S2. The virtual sensor 1 sends the estimated virtual rail pressure value to the input module 2, and the input module 2 forms a rail pressure control signal according to the virtual rail pressure value and the rail pressure set value and sends it to the PID controller 3.

Specifically, the rail pressure control signal in step S2 is equal to the rail pressure set value minus the virtual rail pressure value. It can be understood that when the rail pressure sensor fails, the virtual sensor 1 will play a role, and the common rail system 4 will output the actual value of the rail pressure measured by the rail pressure sensor before the rail pressure sensor fails to the virtual sensor 1 to estimate the virtual The rail pressure value is sent to the input module 2. At this time, the rail pressure setting value minus the virtual rail pressure value is used as the rail pressure control signal of the PID controller 3. As for the specific value of the rail pressure setting value, it is not limited here, and can be set adaptively according to the actual situation; meanwhile, the actual value of the rail pressure and the virtual rail pressure value are also values that change in real time, and are not limited here.

S3. After receiving the rail pressure control signal, the PID controller 3 calculates the control duty ratio of the oil metering unit to control the common rail system 4 .

It can be understood that the PID controller 3 controls the common rail system 4 after calculating the duty cycle of the fuel metering unit, that is, it can control the opening of the inlet throttle valve, so as to achieve the purpose of controlling the rail pressure. As for the specific calculation process and principle of the PID controller 3 calculating the control duty ratio of the fuel metering unit according to the rail pressure control signal, it is already in the prior art, and will not be repeated here.

S4. The virtual sensor 1 estimates the next virtual rail pressure value according to the virtual rail pressure value, and then repeats steps S2-S4.

It can be understood that when virtual sensor 1 estimates the virtual rail pressure value for the first time, it uses the actual rail pressure value measured immediately before the rail pressure sensor fails, and each subsequent estimation of the virtual rail pressure value uses the previous virtual rail pressure value. Pressure value, and then continue to control the common rail system 4 through the PID controller 3, so as to achieve the purpose of closed-loop control.

Optionally, in step S4, the virtual sensor 1 can receive the fuel metering unit control duty ratio and the virtual rail pressure value output by the common rail system 4, and estimate the next virtual rail pressure in combination with the engine speed and the fuel injector power-on time value. Specifically, the virtual sensor 1 estimates the virtual rail pressure value through the formula P ₁ ′=β(Q ₁ −Q ₂ )/V; where: P ₁ ′ is the first derivative of the virtual rail pressure value; β is the fuel elastic modulus; Q ₁ is the average oil supply volume of the high-pressure oil pump; Q ₂ is the average fuel injection volume of the injector; V is the volume of the common rail pipe. The volume deformation of the common rail pipe and the rate of change of oil temperature are ignored in the above formula.

Specifically, Q ₁ =-k ₁ D+b; where: D is the control duty ratio of the fuel metering unit; k ₁ is a constant; b is a constant. It can be understood that the average pump oil supply Q ₁ of high-pressure oil is linearly related to the duty ratio D of the oil metering unit control and the slope is a negative number, k ₁ is the absolute value of the slope, which is a constant, and the specific value is not mentioned here As a limitation, the _k1 values of different types of high-pressure oil pumps are different; at the same time, b is the intercept of the above linear relationship, which is also a constant, and the b values of different types of high-pressure oil pumps are also different. The specific values of _k1 and b in the above formula are not limited here, and can be obtained by consulting the parameter table of the high-pressure oil pump according to the actual situation.

Specifically, since the rail pressure is much greater than the cylinder pressure, Taylor expansion is performed on the flow equation to obtain the average fuel injection quantity Q ₂ =k ₂ TnP of the injector; where: k ₂ is a constant; n is the engine speed; T is the fuel injection The power-on time of the device; P is the last virtual rail pressure value. It can be understood that the Q ₂ obtained by the above formula is an approximate average fuel injection quantity; the specific value of k ₂ is not limited here, and the k ₂ values of different types of injectors are different, and the fuel injection can be queried according to the actual situation The parameter table of the device can be obtained. The engine speed n can be obtained by the speed sensor, and the power-on time T of the fuel injector can be obtained by the control unit of the common rail system 4. As for the specific acquisition method and process, they are already in the prior art and will not be repeated here. In this embodiment, the above formula is also used in step S1 to estimate the virtual rail pressure value, and P at this time is the actual value of the rail pressure measured before the rail pressure sensor fails.

The virtual rail pressure value can be estimated by the above formula, and the virtual sensor 1 is continuously initialized by the actual rail pressure value measured before the rail pressure sensor fails, that is, the actual rail pressure value measured before the rail pressure sensor fails can be used as The initial value when estimating the virtual rail pressure value ensures the accuracy of the value estimation of the virtual sensor 1.

The rail pressure sensor fault handling method provided in this embodiment constructs a virtual sensor 1 through a physical model, and at the same time, uses the actual value of the rail pressure to continuously initialize the virtual sensor 1 before the fault occurs, and stops after the fault occurs, ensuring the value of the virtual sensor 1 The accuracy of estimation improves the effect of rail pressure control in failure mode.

This embodiment also provides a common rail system, including a rail pressure sensor. When the rail pressure sensor fails, the common rail system 4 uses the above rail pressure sensor fault handling method to control the rail pressure. When the rail pressure sensor fails, the common rail system 4 can continue to work, prolonging the service life of the system.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in different forms can also be made. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (5)

1. A rail pressure sensor fault processing method is characterized by comprising the following steps:

s1, determining that a rail pressure sensor is in a fault state, and estimating a virtual rail pressure value by a virtual sensor (1) according to a rail pressure actual value before the rail pressure sensor fails;

s2, the virtual sensor (1) transmits the estimated virtual rail pressure value to an input module (2), and the input module (2) forms a rail pressure control signal according to the virtual rail pressure value and a rail pressure set value and sends the rail pressure control signal to a PID controller (3);

s3, after receiving the rail pressure control signal, the PID controller (3) calculates the control duty ratio of the oil quantity metering unit to control the common rail system (4);

s4, the virtual sensor (1) estimates the next virtual rail pressure value according to the virtual rail pressure value, and then the steps S2-S4 are repeatedly executed;

the step S1 specifically includes: judging whether the rail pressure sensor is in a fault state, if so, estimating the virtual rail pressure value by the virtual sensor (1) according to the rail pressure actual value before the rail pressure sensor is in the fault state, and executing the step S2; if not, executing the step S11;

s11, the common rail system (4) sends the rail pressure actual value to the input module (2), and the input module (2) forms the rail pressure control signal according to the rail pressure actual value and the rail pressure set value and sends the rail pressure control signal to the PID controller (3); then, after the step S3 is executed, the step S11 and the step S3 are repeatedly executed;

in the step S4, the virtual sensor (1) can receive the oil quantity metering unit control duty ratio and the virtual rail pressure value output by the common rail system (4), and estimate the next virtual rail pressure value by combining the engine speed and the power-on time of the oil injector;

the virtual sensor (1) is represented by the formula P ₁ ’＝β(Q ₁ -Q ₂ ) V estimating the virtual rail pressure value;

wherein: p ₁ ' is the first derivative of the virtual rail pressure value; beta is the elastic modulus of the fuel oil; q ₁ The average oil supply quantity of the high-pressure oil pump is obtained; q ₂ The average fuel injection quantity of the fuel injector is obtained; v is the volume of the common rail pipe;

said Q ₁ ＝-k ₁ D+b；

Wherein: d is the control duty ratio of the oil quantity metering unit; k is ₁ Is a constant; b is a constant;

said Q ₂ ＝k ₂ TnP；

Wherein: k is a radical of ₂ Is a constant; n is the engine speed; t is the power-on time of the oil sprayer; p is the last virtual rail pressure value;

wherein, the formula P is also adopted in the step S1 ₁ ’＝β(Q ₁ -Q ₂ ) V, said Q ₁ ＝-k ₁ D + b, said Q ₂ ＝k ₂ And TnP estimates the virtual rail pressure value, wherein P at the moment is the actual rail pressure value measured before the rail pressure sensor fails.

2. The rail pressure sensor fault handling method according to claim 1, wherein the rail pressure actual value continuously initializes the virtual sensor (1) when step S11 is executed, and the initialization is stopped when it is determined that the rail pressure sensor is in a fault state.

3. The rail pressure sensor fault handling method of claim 1, wherein the rail pressure control signal is equal to the rail pressure set value minus the rail pressure actual value in step S11.

4. The rail pressure sensor fault handling method of claim 1, wherein the rail pressure control signal is equal to the rail pressure set value minus the virtual rail pressure value in step S2.

5. A common rail system characterized by comprising a rail pressure sensor, wherein when the rail pressure sensor malfunctions, the common rail system (4) performs rail pressure control using the rail pressure sensor malfunction processing method according to any one of claims 1 to 4.

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