WO2014075468A1

WO2014075468A1 - Method of collecting and monitoring oil path pressure signal

Info

Publication number: WO2014075468A1
Application number: PCT/CN2013/080891
Authority: WO
Inventors: 李伯承
Original assignee: 奇瑞汽车股份有限公司; 芜湖普威技研有限公司
Priority date: 2012-11-19
Filing date: 2013-08-06
Publication date: 2014-05-22
Also published as: CN103016181A

Abstract

Disclosed is a method of collecting and monitoring an oil path pressure signal, wherein a central processing unit uses a path pressure sensor to measure an oil injection path pressure signal at the point of oil injection and a peak path pressure signal within a pre-set time interval T, and controls the amount of oil injected according to the oil injection path pressure signal; the central processing unit also determines whether or not the peak path pressure signal exceeds a pre-set range, and monitors the dynamic drift of the peak path pressure signal in the start-up phase; when the peak path pressure signal exceeds the pre-set range or the dynamic drift of the peak path pressure signal exceeds the pre-set value, the central processing unit substitutes the actual path pressure signal with a pre-set path pressure value, thereby entering a limp home mode. The method can better serve an engine, making engine operation even more highly efficient.

Description

Method for collecting and monitoring oil pressure signal

This application claims priority to Chinese Patent Application No. 201210464531.7, entitled "A Method for Collecting and Monitoring Oil Pressure Signals" by the Chinese Patent Office on November 19, 2012, the entire contents of which are incorporated by reference. In this application. Technical field

The invention relates to the technical field of a vehicle complete power transmission control system, and is a concrete realization of a control system for collecting, monitoring and solving a fuel pressure in a fuel rail of a power system, which can be used for a high pressure common rail diesel engine and a direct injection gasoline engine. vehicle. In particular, it relates to a method for collecting and monitoring a rail pressure signal. Background technique

In the current form of energy shortage, high-pressure common rail diesel engines have been increasingly used in the passenger vehicle field because of their low fuel consumption and low pollution. The emergence of in-cylinder direct injection gasoline engines has made the rail pressure of the power system a more important input parameter for the power system control strategy. If the calculation of the oil rail pressure is inaccurate, it will lead to inaccurate fuel injection calculation, which will result in unstable engine performance, which will affect the power, economy and emissions of the engine and the vehicle, and will also make the power system components reliable. Sex and durability are facing a severe test. At present, a small number of systems with monitoring functions can realize the collection and monitoring of the oil rail pressure, but the monitoring strategy is relatively simple, and it can not achieve real-time, accurate and comprehensive monitoring. The collected data will be unreasonable and the oil pressure can not be reflected in real time. Changes, as well as faulty and false reported defects. Summary of the invention

It is an object of the present invention to provide a real-time, accurate, and comprehensive method of collecting and monitoring rail pressure signals to improve engine performance.

The method for collecting and monitoring the fuel rail pressure signal of the present invention is as follows: The central processing unit uses the rail pressure sensor to measure the fuel injection pressure signal at the injection time point and the peak rail pressure signal in the predetermined interval time T, and according to the fuel injection rail pressure Signal to control the fuel injection amount; the central processing unit also determines whether the peak rail pressure signal is exceeded The predetermined range, and the dynamic drift of the peak rail pressure signal is monitored during the startup phase. When the peak rail pressure signal exceeds the predetermined range or the dynamic drift of the peak rail pressure signal exceeds a predetermined value, the central processing unit replaces the predetermined rail pressure value. The actual rail pressure signal, thus entering the Limp Home mode.

Specifically, after the system is powered on, the central processing unit reads the stored engine water temperature t_last of the previous driving cycle, and then compares the current water temperature t_time with t_last, if the current water temperature Uirne decreases more than t_last The value t_const, and the engine speed is equal to zero at this time, that is, the oil pressure at this time is equal to the atmospheric pressure, and the dynamic drift monitoring is started; if the central processing unit reads the previous driving cycle water temperature t_last fails after the system is powered on, or the current If the difference between the water temperature t_time and Uast does not exceed the set value ( 01^ , or the engine speed is greater than zero, the dynamic drift detection is not performed. Strict control of the dynamic drift detection during the start-up phase can make the test result unaffected by the engine, thus ensuring accuracy Reliable.

Further, the central processing unit confirms that the fault is true only if the peak rail pressure signal exceeds the predetermined range within a predetermined time length Tcon or the dynamic drift of the peak rail pressure signal exceeds a predetermined value, and the fault occurs but is not central The processing unit confirms that it is in real time, and the central processing unit uses the last measured peak rail pressure signal as the actual rail pressure signal; when the central processing unit confirms that the fault is true, the central processing unit replaces the actual rail pressure signal with the predetermined rail pressure value, thereby Enter the Limp Home mode. By setting a time length Tcon to confirm whether the fault is true, and using the last measured peak rail pressure signal as the actual rail pressure signal after the fault occurs and in the unconfirmed phase, it can avoid the misjudgment caused by occasional signal interference. Take too conservative or intense treatment methods, which in turn affects the work of the engine.

Further, when measuring the peak rail pressure signal within the predetermined interval time T, the central processing unit first collects the pressure value every T1 time, and stores the collected pressure value in a data buffer, and then every T time. Taking the maximum value of the pressure value stored in the data buffer as the peak rail pressure signal of the acquisition, using the peak rail pressure signal for system control and fault monitoring;

T1 is less than τ.

Further, when measuring the fuel injection pressure signal at the injection time, the central processing unit first sets an injection dynamic switch, and controls the injection dynamic switch to close before each system injection, thereby collecting the current fuel rail. pressure.

The method for collecting and monitoring the rail pressure signal of the present invention can better serve the engine and make the engine work more efficiently by adopting an innovative approach in the stages of signal acquisition, fault judgment and processing. DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present invention. Other drawings may also be obtained from those of ordinary skill in the art in light of the inventive work.

Figure 1 is a flow chart of the fuel rail pressure signal acquisition;

Figure 2 is a flow chart of the rail pressure signal monitoring;

Figure 3 is a flow chart of the oil pressure dynamic drift detection;

Figure 4 is a flow chart of fault confirmation. detailed description

The specific embodiments of the present invention, such as the shape and structure of the components involved, the mutual position and connection relationship between the parts, the functions and working principles of the parts, etc., are further described below with reference to the accompanying drawings. Detailed description.

Example 1

The method for collecting and monitoring the fuel rail pressure signal of the present invention is as follows: The central processing unit uses the rail pressure sensor to measure the fuel injection pressure signal at the injection time point and the peak rail pressure signal in the predetermined interval time T, and according to the fuel injection rail pressure The signal is used to control the fuel injection amount; the central processing unit also determines whether the peak rail pressure signal exceeds a predetermined range, and monitors the dynamic drift of the peak rail pressure signal during the startup phase, when the peak rail pressure signal exceeds a predetermined range or peak rail pressure signal When the dynamic drift exceeds a predetermined value, the central processing unit enters the Limp Home mode by replacing the actual rail pressure signal with a predetermined rail pressure value.

Specific steps are as follows:

As shown in Figure 1, the central processing unit is used to collect the output signal of the sensor for the role of the rail pressure signal in the system (the ADC in the figure is an analog-to-digital conversion unit):

One is as a fuel rail pressure signal, and the fuel rail pressure signal is collected by setting a fuel injection dynamic switch, and controlling the fuel injection dynamic switch to be closed before each injection to collect the current rail pressure. Fuel injection includes main spray, pre-spray and post spray. This pressure is the injection pressure of this fuel. In this way, the injection pressure can be calculated more accurately, so that the fuel injection amount can be accurately calculated and controlled.

The other is a peak rail pressure signal as a system control parameter, which is described with a predetermined interval time T of 10 ms, and the peak rail pressure signal is a maximum value of the pressure within 10 ms. Central processing unit first set A lms timer switch that collects the pressure value every millisecond, then stores it in a buffer that can store 10 acquisition data, and then sets a 10ms timer switch to set the maximum value of the pressure value stored in the data buffer every 10ms. It is taken out as the peak pressure of this acquisition, and this peak pressure is used for system control and fault monitoring.

As shown in Figure 2, after collecting the fuel rail pressure signal and the peak rail pressure signal, the central processing unit uses the fuel rail pressure signal to control the fuel injection quantity and determine whether the peak rail pressure signal is faulty. That is, it is judged whether the peak rail pressure signal is within a set reasonable range, or whether the peak rail pressure signal dynamic drift is excessive. When the peak rail pressure signal is out of the reasonable range or the dynamic drift is too large, the fault handling phase is performed.

The step of determining whether the dynamic drift of the peak rail pressure signal is too large is shown in FIG. 3. After the system is powered on, the central processing unit reads the stored engine water temperature tjast of the previous driving cycle, and then the current water temperature t_time and t_last. In comparison, if the current water temperature t_time is lower than the set value t_const by t_last, and the engine speed is equal to zero at this time, it means that the engine has not established the rail pressure at this time, that is, the rail pressure should be equal to the atmospheric pressure, if the pressure drifts at this time. If it is too large, it is judged that the measurement of the rail pressure signal is inaccurate, that is, the fault is detected. If the central processing unit reads the water temperature tjast of the previous driving cycle after the system is powered on, or the difference between the current water temperature t_time and tjast does not exceed When the set value is 1_( 01^ , or the engine speed is greater than zero, the dynamic drift detection is not performed. Strict control of the dynamic drift detection during the start-up phase can make the test result unaffected by the engine, thus ensuring accuracy and reliability.

Further, after the fault occurs, the system does not immediately store the fault in the fault memory. The central processing unit needs to confirm the fault. Only when the fault persists for a certain period of time, the fault is confirmed. That is, the central processing unit confirms that the fault is true only if the peak rail pressure signal exceeds the predetermined range within the predetermined time length Tcon or the dynamic drift of the peak rail pressure signal exceeds the predetermined value, and the fault occurs but the central processing unit is not present. The confirmation is real-time, the central processing unit uses the last measured peak rail pressure signal as the actual rail pressure signal; when the central processing unit confirms that the fault is true, the central processing unit replaces the actual rail pressure signal with the predetermined rail pressure value to enter the Limp. Home mode. By setting a time length Tcon to confirm whether the fault is true, and using the last measured peak rail pressure signal as the actual rail pressure signal after the fault occurs and in the unconfirmed phase, it can avoid the misjudgment caused by occasional signal interference. Take too conservative or intense treatment methods, which in turn affects the work of the engine.

As shown in Figure 4 (in Figure 4, AB < Tcon < CD.), the fault is detected in the AB phase, but since the fault occurrence time does not reach the system-set fault confirmation time Tcon, the fault is not confirmed. It is recognized that in the AB phase, the central processing unit uses the last measured peak rail pressure signal as the actual rail pressure signal. The fault is detected again in the CD phase, and the fault occurrence time reaches the fault check time Tcon set by the system, and the fault is confirmed and stored. Before point D, the system rail pressure takes the last measured effective value. After point D, the central processing unit replaces the actual rail pressure signal with the predetermined rail pressure value. At this point, the system enters the Limp Home mode, that is, the limp home mode. The meter indicator lights to inform the driver that the system is faulty and needs to be repaired. A person skilled in the art may understand that all or part of the steps of implementing the above embodiments may be completed by hardware, or may be instructed by a program to execute related hardware, and the program may be stored in a computer readable storage medium. The storage medium mentioned may be a read only memory, a magnetic disk or an optical disk or the like. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

claims

1. A method for collecting and monitoring fuel rail pressure signals, characterized in that the central processing unit uses a rail pressure sensor to measure the fuel injection rail pressure signal at the injection time point and the peak rail pressure signal within the predetermined interval time T, and based on the injection The fuel rail pressure signal is used to control the fuel injection amount; the central processing unit also determines whether the peak rail pressure signal exceeds the predetermined range, and monitors the dynamic drift of the peak rail pressure signal during the startup phase. When the peak rail pressure signal exceeds the predetermined range or the peak rail When the dynamic drift of the pressure signal exceeds a predetermined value, the central processing unit replaces the actual rail pressure signal with the predetermined rail pressure value, thus entering the Limp Home mode.

2. The method for collecting and monitoring fuel rail pressure signals according to claim 1, characterized in that after the system is powered on, the central processing unit reads the stored engine water temperature tjast of the previous driving cycle, and then sets the current Compare the water temperature t_time with t_last. If the current water temperature t_time is lower than the t_last by more than the set value t_const, and the engine speed is equal to zero at this time, it can be considered that the fuel rail pressure at this time is equal to the atmospheric pressure, and dynamic drift monitoring starts; If on the system After power-on, if the central processing unit fails to read the water temperature tjast of the previous driving cycle, or the difference between the current water temperature t_time and tjast does not exceed the set value t_const, or the engine speed is greater than zero, dynamic drift detection will not be performed.

3. The method for collecting and monitoring fuel rail pressure signals according to claim 1 or 2, characterized in that only within a predetermined time length Tcon, the peak rail pressure signal exceeds a predetermined range or the dynamic drift of the peak rail pressure signal exceeds a predetermined value. The central processing unit only confirms that the fault is true when the fault persists. When the fault occurs but is not confirmed by the central processing unit, the central processing unit takes the last measured peak rail pressure signal as the actual rail pressure signal; when the central processing unit confirms After the fault is confirmed, the central processing unit replaces the actual rail pressure signal with the predetermined rail pressure value, thereby entering the Limp Home mode.

4. The method for collecting and monitoring fuel rail pressure signals according to claim 3, characterized in that when the central processing unit measures the peak rail pressure signal within the predetermined interval time T, it first collects the pressure value every T1 time, and Store the collected pressure value in a data buffer, and then take out the maximum value of the pressure value stored in the data buffer every T time as the peak rail pressure signal collected this time, and use this peak rail pressure signal to Carry out system control and fault monitoring; the T1 is smaller than T.

5. The method for collecting and monitoring fuel rail pressure signals according to claim 3, characterized in that when the central processing unit measures the fuel injection rail pressure signal at the fuel injection time point, it first sets an injection dynamic switch and controls the fuel injection dynamic switch. The injection dynamic switch is closed before each system injection to collect the current fuel rail pressure.