CN112664319B - Control system and fault diagnosis method for aviation piston two-stroke supercharged engine - Google Patents
Control system and fault diagnosis method for aviation piston two-stroke supercharged engine Download PDFInfo
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Abstract
The invention discloses a control system and a fault diagnosis method of an aviation piston two-stroke supercharged engine, and belongs to the field of two-stroke aviation piston supercharged engines. The fault diagnosis method comprises the following steps: obtaining engine operation parameters, and performing preliminary diagnosis on sensor signals; establishing an engine air inflow calculation model and calculating the engine air inflow; determining the oil injection pulse width, controlling the oil injection pulse width by adopting a feed-forward and feedback closed-loop fuel injection control method, and executing an oil injection action; generating an ignition timing signal according to the ignition advance angle, and executing an ignition action; and (5) carrying out fault diagnosis on the exhaust system, positioning fault reasons and giving an alarm. The method establishes an engine air inflow model, enables the engine to always work in the optimal air-fuel ratio range through a feedforward and feedback control mode according to air inflow and air-fuel ratio data, and carries out fault diagnosis on the engine working environment and the vulnerable point of a supercharged engine by a system self-diagnosis function.
Description
Technical Field
The invention is applied to the field of two-stroke aviation piston supercharged engines, and particularly relates to an aviation piston two-stroke supercharged engine control system and a fault diagnosis method thereof.
Background
The technology is applied to a two-stroke aviation piston supercharged engine. Different from a common natural suction two-stroke engine, the aviation piston two-stroke supercharged engine needs to recycle exhaust pulse energy to do work, and exhaust has higher temperature and certain pressure, so that a system needs to bear higher pressure and impact force. Improper engine control strategies can affect in-cylinder combustion efficiency and work efficiency, worsen engine system vibration impact conditions, and cause structural damage. To preserve the life of the system components, there are higher demands on the control system than with naturally aspirated engines.
The ignition and oil injection control parameters are changed along with various factors, the ignition advance angle is accurately calculated, the optimal air-fuel ratio under various working conditions is obtained, and the aim of the control system is to enable the engine to exert the optimal working performance. The aero-engine works under the condition of variable altitude and multiple working conditions, and the conditions such as altitude, temperature and the like directly influence the air input of the engine, so that the oil injection quantity is influenced. The existing pulse spectrum control method based on the bench calibration cannot be adjusted according to the characteristic difference and the gradual change characteristic of an executive device and a related sensor, and the engine cannot be guaranteed to be in the optimal working state. In addition, due to the hysteresis of signal measurement and transmission, the conventional oil passage closed-loop control based on the feedback control of the oxygen sensor is in a passive position in the adjustment of the transient air-fuel ratio. In order to ensure that the engine can still efficiently and stably output the target torque under the extreme environment, a control strategy is required to be capable of adapting to various extreme environments and ensure that the engine can normally work under the extreme environments.
The Control basis of an Electronic Control Unit (ECU) for the operation of an engine is measurement signals of various sensors, the accuracy of the signals is a precondition for the ECU to Control correctly, and the sensors, the signals and structural faults can cause the ECU to judge the state of the engine by mistake, so that the Control system needs to have a self-diagnosis function to prevent the wrong Control caused by the wrong judgment.
Disclosure of Invention
In order to solve the problems, the invention provides an aviation piston two-stroke supercharged engine control system and a fault diagnosis method thereof.
According to a first aspect of the present invention there is provided a method of fault diagnosis for an aviation piston two-stroke supercharged engine, the method comprising:
step 1: acquiring engine operation parameters through a sensor, and performing preliminary diagnosis on a sensor signal;
step 2: establishing an engine air inflow calculation model and calculating air inflow;
and step 3: determining oil injection pulse width according to air inflow, air-fuel ratio data and engine working condition parameters of the engine, controlling the oil injection pulse width by adopting a feed-forward and feedback closed-loop fuel injection control method, and executing oil injection action;
and 4, step 4: generating an ignition timing signal according to the ignition advance angle, and executing an ignition action;
and 5: and diagnosing faults of the air intake and exhaust system and positioning the fault reasons.
Further, in step 1, the preliminary diagnosis includes:
electrical appliance level diagnosis: detecting through a short power supply, a short ground and an open circuit method;
and (3) rationality diagnosis: and judging whether the received data is in a reasonable range of the signals of the sensors under each working condition of the engine through a bench test.
Furthermore, in the step 2, an engine air inflow calculation model is provided by using a slope-intercept method, the engine air inflow calculation model fits a function relation between the engine air inflow and the air inflow pressure of the pressure stabilizing cavity under the specific pressure stabilizing cavity air inflow temperature, the specific engine speed and the specific throttle opening through test data, and the engine air inflow calculation model is used for determining the engine air inflow through the air inflow pressure of the pressure stabilizing cavity.
Further, the engine intake air amount calculation model is as follows:
R＝(P manifold -P residualr )*K；
wherein R is engine intake air quantity, P manifold For maintaining the inlet pressure of the pressure chamber, P residualr For the residual gas pressure in the crankcase, relevant to the rotating speed and the mechanical characteristics of the engine, K is a conversion factor of the air inlet pressure of the pressure stabilizing cavity and the relative air inflation quantity, and the method specifically comprises the following steps:
K＝K v *K t *K f *K p ；
wherein, K v Is an effective volume factor of the cylinder, and is dimensionlessParameter, the value of which depends on the mechanical properties of the engine, K p For the intake air flow loss coefficient, which is related to the engine speed and mechanical characteristics, K t For temperature correction factor, related to the inlet temperature of the plenum chamber, K f The nonlinear correction coefficient of the intake efficiency curve under the full-load working condition is related to the engine speed, the load and the mechanical characteristics of the engine.
Further, the step 2 specifically includes:
step 21: the engine maintains a certain rotating speed, the opening of a throttle valve is adjusted, the air inlet temperature of a pressure stabilizing cavity is maintained within a certain range, the air inlet amount of the engine is measured through an air flow meter, and the air inlet temperature in the pressure stabilizing cavity and the air inlet pressure of the pressure stabilizing cavity are measured through a temperature and pressure sensor;
step 22: performing data fitting by a regression analysis method, and calculating P under the current inlet air temperature of the pressure stabilizing cavity residualr And K;
step 23: maintaining the inlet air temperature of the current pressure stabilizing cavity unchanged, changing the rotating speed of the engine, and calculating P under different rotating speeds of the engine and different opening degrees of the throttle valve according to steps 21 and 22 residualr K, forming the opening of a throttle valve, the rotating speed of the engine and P under the air inlet temperature of the current pressure stabilizing cavity residualr And a three-dimensional table of throttle opening, transmitter rotating speed and K, acquiring the current engine rotating speed and throttle opening, and obtaining P through interpolation calculation residualr K, obtaining the air inflow of the engine according to the air inflow pressure of the pressure stabilizing cavity;
and step 24: and (5) adjusting the air inlet temperature of the pressure stabilizing cavity, and repeating the steps 21 to 23 to obtain a coefficient table look-up table under different air inlet temperatures of the pressure stabilizing cavity.
Furthermore, in step 3, the fuel injection pulse width is preset by using the air inflow of the transmitter according to the bench test data by a self-learning method, the fuel injection pulse width is corrected again by feeding back an air-fuel ratio signal in the operation process, so that the air-fuel ratio is stabilized near a target value, and the fuel injection action is executed.
Further, the step 3 specifically includes:
step 31: the fuel injection pulse width distribution MAP (MAP) of basic fuel injection obtained through a bench calibration test and the corrected fuel injection pulse width distribution MAP (MAP) of cylinder temperature, atmospheric pressure and pressure stabilizing cavity air inlet temperature are stored in a table form, and the ECU performs table lookup interpolation calculation on a first fuel injection pulse width according to the real-time engine rotating speed and a throttle opening value and corrects the first fuel injection pulse width through the cylinder temperature, the atmospheric pressure and the pressure stabilizing cavity air inlet temperature;
step 32: determining target air-fuel ratios under different working conditions, calculating the required oil quantity by using the engine air inflow and the target air-fuel ratio which are calculated by the engine air inflow calculation model, and calculating a second oil injection pulse width according to the characteristics of the oil injector;
step 33: carrying out weighted average on the first oil injection pulse width and the second oil injection pulse width obtained in the steps 31 and 32 to obtain a preset oil injection pulse width;
step 34: and correcting the preset oil injection pulse width by adopting a Proportional-Integral-Derivative (PID) control algorithm according to the difference value between the current air-fuel ratio signal and the target air-fuel ratio to obtain the final oil injection pulse width, and executing the oil injection action.
Further, the step 5 specifically includes:
step 51: through a plurality of test tests, typical fault types in the running process of the engine are summarized, corresponding relations are established between abnormal data and fault cases, a data table is formed, and the data table is stored in an ECU;
step 52: when corresponding abnormal data occurs in the operation of the engine, the ECU compares the abnormal data with the past abnormal data in the data table, judges the fault type and uploads a fault code to warn.
According to a second aspect of the present invention there is provided a control system for an aviation piston two-stroke supercharged engine, the control system being fault-diagnosed based on the method of any one of the preceding aspects, the control system comprising:
the ECU is used for monitoring sensor signals, performing functional diagnosis and sending instructions to the actuator;
a plurality of sensors, comprising: the system comprises a cylinder temperature sensor (2 paths), a heat exhaust sensor (2 paths), a crankshaft position signal sensor (2 paths), an air inlet temperature pressure sensor, a throttle valve position sensor (2 paths), an oil pressure sensor and a wide-range oxygen sensor, wherein the cylinder temperature sensor (2 paths), the heat exhaust sensor (2 paths), the crankshaft position signal sensor (2 paths), the air inlet temperature pressure sensor, the throttle valve position sensor (2 paths), the oil pressure sensor and the wide-range oxygen sensor are used for sensing data signals;
and the actuator comprises an oil injector, an ignition coil and a throttle valve and is used for executing corresponding operation according to the instruction of the ECU.
The invention has the beneficial effects that:
according to the invention, aiming at the characteristics of the supercharged engine and the plateau working environment, oil injection is accurately controlled, and the performance of the engine in the extreme working environment is greatly improved; the air-fuel ratio is subjected to feedforward and feedback closed-loop control, so that the target air-fuel ratio under various working conditions can be obtained, and the preset control can effectively reduce the closed-loop calculation time and increase the response speed; the system self-diagnosis function monitors the sensor signals and the air intake and exhaust working states of the engine, and is beneficial to quickly positioning or eliminating related faults when the working states of the engine are abnormal.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
In the drawings:
FIG. 1 illustrates a control system schematic according to an embodiment of the present invention;
FIG. 2 illustrates a flow chart of a fuel injection pulsewidth calculation according to an embodiment of the present disclosure;
FIG. 3 illustrates a flow chart of closed-loop correction of injection pulsewidth according to an embodiment of the present disclosure;
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.
The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
A plurality, including two or more.
And/or, it should be understood that, as used herein, the term "and/or" is merely one type of association that describes an associated object, meaning that three types of relationships may exist. For example, a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone.
S1: the operating parameters of the supercharged engine are obtained through the sensors, and the rotating speed, the air inlet pressure, the air inlet temperature, the air-fuel ratio and the like are obtained through calculation.
S2: sensor signal diagnostics including appliance level diagnostics and rationality diagnostics. The electric appliance level diagnosis is detected by a short power supply, short ground and open circuit method, the rationality diagnosis determines the reasonable range of signals of each sensor under each working condition of the engine by a rack test and a statistical method, and judges whether the received data is in the reasonable range.
S3: and the ECU determines the ignition or oil injection timing of the engine by taking the engine crankshaft position signal acquired by the crankshaft position sensor as a reference, and judges the current operation condition of the engine.
S4: and calculating air inflow according to the pressure of the pressure stabilizing cavity measured by the air inflow temperature and pressure sensor, and establishing a simulation model by using the data measured by the sensor to calculate the relative air amount. The invention utilizes a slope-intercept method to develop an engine air input calculation model, measures the air inlet pressure, the air inlet temperature and the engine air input in a pressure stabilizing cavity, and obtains the functional relation between the engine air input and the pressure of the pressure stabilizing cavity at a specific rotating speed through data fitting. By using the function, the air inflow of the engine can be determined through the pressure of the pressure stabilizing cavity.
S5: the fuel injection pulse width is determined according to air inflow, air-fuel ratio data and engine working condition parameters, a feed-forward and feedback closed-loop fuel injection control method is adopted, namely fuel injection quantity is preset by a self-learning method according to bench test data by utilizing the air inflow, and the fuel injection quantity is corrected again through air-fuel ratio signal feedback in the running process, so that the air-fuel ratio is stabilized near a target value. And the ECU executes the oil injection action according to the finally calculated oil injection pulse width.
S6: the ECU generates an ignition timing signal according to the ignition advance angle and executes an ignition action.
S7: the air path fault diagnosis and ECU system self-diagnosis function comprises the corresponding relation between the existing data abnormal phenomenon and the fault, and when the engine operation data is abnormal, the ECU can be compared with the former abnormal data to quickly locate the related fault.
In step S5, the basic injection pulse width is obtained by checking MAP from throttle position and rotation speed signals acquired by the ECU, and correcting parameters such as cylinder temperature and air pressure, and the injection MAP is obtained by test calibration during engine design and matching. The calculation mode of the ignition advance angle is the same as the fuel injection pulse width, the basic ignition angle is obtained by table lookup, and the final result is obtained through global correction, temperature correction and pressure correction.
Examples
Fig. 1 shows the control principle of the whole electric control system of this embodiment, which includes an engine electric control unit ECU, various sensors and an actuator, where the sensors include a cylinder temperature sensor (2 ways), a heat-removal sensor (2 ways), a crankshaft position signal sensor (2 ways), an intake air temperature pressure sensor, a throttle position sensor (2 ways), an oil pressure sensor and a wide-range oxygen sensor, and the actuator includes an oil injector, an ignition coil and a throttle.
When the engine works, after information collected by each sensor is transmitted into the ECU, the ECU firstly carries out self-diagnosis, and the signals are allowed to participate in control parameter calculation within a reasonable range. The crankshaft position signal sensor detects a crankshaft position signal and sends the crankshaft position signal to the ECU in a pulse mode, and the ECU calculates the rotating speed according to the crankshaft position signal and determines an ignition phase and an oil injection phase by taking the tooth missing position of the crankshaft as a reference.
And the ECU acquires the current throttle position and rotation speed signals, calculates by looking up a table to obtain a basic ignition advance angle, and obtains a final ignition advance angle through cylinder temperature and air pressure correction.
The flow of the oil injection pulse width is shown in figure 2, an air inlet temperature and pressure sensor is arranged in a pressure stabilizing cavity, an oxygen sensor is arranged in an exhaust pipe, an ECU acquires air inlet pressure data to calculate the air inlet amount of an engine, and the basic oil injection pulse width obtained by table lookup is corrected according to the air inlet amount, an air-fuel ratio signal and a temperature and pressure signal to ensure that the air-fuel ratio is maintained near a target air-fuel ratio so as to ensure that the combustion of mixed gas reaches the optimal state.
Intake air quantity calculation
The air inflow calculation model for calculating the air inflow is calculated based on the pressure of the pressure stabilizing cavity, and the calculation formula is as follows:
R＝(P manifold -P residualr )*K；
wherein R is the air intake of the cylinder, P manifold To stabilize the pressure in the cavity, P residualr The pressure of residual gas in a crankcase is related to the rotating speed and mechanical characteristics of an engine, and K is a conversion factor of the pressure of a pressure stabilizing cavity and relative air charging quantity.
K＝K v *K t *K f *K p ；
Wherein, K v A dimensionless parameter being the effective volume factor of the cylinder, the value of which depends on the mechanical properties of the engine, K p K is an intake flow loss coefficient, which is related to engine speed and mechanical characteristics t As a temperature correction factor, related to the intake air temperature, K f The nonlinear correction coefficient of the intake efficiency curve under the full-load working condition is related to the engine speed, the load and the mechanical characteristics of the engine. From the above analysis, it can be understood that K is affected by the engine speed, load, and intake air temperature for the engine with the configuration parameters determined, and K is f (spd, T) AirIn, D Throtle ) Wherein spd is the engine speed, T AirIn Is the intake air temperature, D Throtle The opening degree of a throttle valve.
It can be seen that the intake air amount is a linear function of the intake air pressure, and the slope and intercept thereof are affected by the engine speed and the intake air temperature. Determine P by way of bench test residualr And K. The parameter determination method comprises the following steps:
(1) the engine maintains a certain rotating speed, the opening of a throttle valve is adjusted, the air inlet temperature is maintained within a certain range, the air inlet amount of the engine is measured through an air flow meter, and the air inlet temperature and the air inlet pressure in a pressure stabilizing cavity are measured through a temperature and pressure sensor.
(2) Performing data fitting by a regression analysis method, and calculating P at the current inlet air temperature residualr And K.
(3) Keeping the current air inlet temperature unchanged, changing the rotating speed of the engine, and calculating P under different rotating speeds and throttle openings according to the steps (1) and (2) residualr And K, forming the opening degree, the rotating speed and the P of a throttle valve at the current temperature residualr And a three-dimensional table of throttle opening, rotating speed and K, wherein the current rotating speed and throttle opening are acquired, and P is obtained in an interpolation calculation mode residualr And K, further obtaining the air inflow according to the air inlet pressure of the pressure stabilizing cavity.
(4) And (4) adjusting the air inlet temperature, and repeating the steps (1), (2) and (3) to obtain a coefficient table look-up table under different air inlet temperatures.
Feed-forward plus feedback fuel injection control
FIG. 3 is a flow chart of an algorithm for calculating closed-loop correction of fuel injection pulsewidth by the ECU, which employs feedforward plus feedback closed-loop fuel injection control, including two parts of closed-loop control and preset control based on air-fuel ratio.
The engine has a wide range of operating conditions, the required mixed gas air-fuel ratios under different rotating speeds are different, in order to ensure that the engine can meet the requirements of dynamic property and reliability under different operating condition modes, an air-fuel ratio zone control mode is adopted, different rotating speed areas are controlled based on different target air-fuel ratios, and the target air-fuel ratios in the different rotating speed areas are shown in the following table 1.
TABLE 1 target air-fuel ratio for different speed intervals
| Interval of rotation/rpm | Air-fuel ratio demand |
| Less than 3000 | 8.9-9.1 |
| 3000-3600 | 8.4-8.8 |
| 3600-3850 | 8.6-8.8 |
| 3850-4000 | 8.8 |
| 4000-5000 | 9.1 |
| 5000-5200 | 8.9 |
| 5200 or more | 8.5 |
PID closed-loop control is adopted, the closed-loop correction amount is proportional term + integral term + differential term, the proportional correction term is a reverse correction amount applied when the concentration change of the mixed gas is detected, when the mixed gas is lean, the mixed gas is enriched by a certain step length, and when the mixed gas is rich, the gas injection amount is reduced by a certain step length, so that the mixed gas is always kept near the target air-fuel ratio. The integral term compensates the deviation of the actual air-fuel ratio to the target air-fuel ratio, and influences the fluctuation and amplitude of the air-fuel ratio, the longer the integral step length is, the shorter the calculation period is, and the faster the integral correction is, so the small step length is used for medium and small loads, and the large step length is used for large loads, and in addition, in order to ensure that the integral correction term is in a reasonable range, the integral correction amount needs to be limited, the limit value represents the correction amount of the oil injection pulse width, the limit of the medium and small loads is smaller, and the limit of the large load is larger. After being calibrated by a plurality of tests, the PID control parameter can quickly adjust the oil injection pulse width to stabilize the air-fuel ratio near the target air-fuel ratio.
In order to ensure the transient response real-time performance of the control system, the MAP obtained by the calibration test of the engine pedestal in advance is calculated and stored in a table form, and the ECU calculates the oil injection pulse width according to the real-time rotating speed and the table lookup interpolation of the throttle valve. When the actual structural parameters of the engine are changed due to product tolerance or aging and abrasion or the fuel quality is changed, the air-fuel ratio and the target value have larger deviation by calculating according to the calibrated MAP. Calculating the fuel injection quantity by utilizing the air inflow and the target air-fuel ratio which are calculated by the air inflow calculation model, wherein the calculation method comprises the following steps:
the fuel injection quantity is equal to the air intake quantity/target air-fuel ratio;
converting the fuel injection quantity into fuel injection pulse width according to the characteristics of the fuel injector, comparing the fuel injection pulse width with the fuel injection pulse width obtained by the MAP table look-up and cylinder temperature and air pressure correction, correcting by a weighted average method to obtain preset fuel injection pulse width, wherein the calculation method comprises the following steps:
y is a/(a + b) fuel injection amount _ intake + b/(a + b) MAP _ fuel injection;
wherein: a, fitting data measured by a bench test off line;
the software self-learning function can adjust the MAP to be close to the optimal value after the calibrated MAP runs for a period of time. The correction formula of the self-learning value to the fuel injection quantity is as follows:
InjWid＝InjWidMap*SL/128
the method comprises the following steps that InjWidMap is an oil injection pulse width value obtained by table lookup, SL is a learning value of a current self-learning unit, and the self-learning value is determined according to the deviation between an actual air-fuel ratio and a target air-fuel ratio; the range is +/-25% of the current oil injection pulse width index value.
System self-diagnosis
The system self-diagnosis function is divided into sensor signal diagnosis and state fault diagnosis, and the sensor signal diagnosis is divided into drive level diagnosis and signal rationality diagnosis. The method comprises the steps that for a complete failure fault of a sensor, in the non-running state of an engine, signals under the condition of line faults of the sensor are obtained through a short power supply, a short ground and an open circuit mode, the signal range of the sensor in normal working is determined and written into software, after an ECU receives signals of the sensor, in order to prevent fault misjudgment, average filtering is carried out on 10 signals collected every time, and whether the filtered values are in the normal working signal range or not is judged. And aiming at the sensor precision reduction fault, the rationality diagnosis also determines the critical value through a critical value judgment method, the critical value is determined through the maximum value and the minimum value of the filtered numerical value under the same working condition, the maximum value and the minimum value are recalculated once every time one datum is received, the weighted average value of the maximum value and the minimum value is calculated to obtain a critical range, and the critical value is always between the maximum value and the minimum value of the appeared actual signal of the sensor.
Air intake and exhaust system leaks necessarily have an effect on engine operation. Through a plurality of test tests, typical fault cases in the running process of the engine are gathered, data abnormal phenomena correspond to the fault cases one by one, the self-diagnosis function of the ECU system comprises the corresponding relation between the existing data abnormal phenomena and faults, and when the corresponding abnormal phenomena occur in the running data of the engine, the ECU can compare with the existing abnormal data, judge the faults and upload fault codes for warning. The relevant faults of the intake and exhaust system that the ECU can locate are shown in table 2 below.
TABLE 2 analysis of engine intake and exhaust system faults
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element identified by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (7)
1. A fault diagnosis method for an aviation piston two-stroke supercharged engine is characterized by comprising the following steps:
step 1: acquiring engine operation parameters through a sensor, and performing preliminary diagnosis on a sensor signal;
step 2: establishing an engine air inflow calculation model and calculating the engine air inflow;
and 3, step 3: determining oil injection pulse width according to air inflow, air-fuel ratio data and engine working condition parameters of the engine, controlling the oil injection pulse width by adopting a feed-forward and feedback closed-loop fuel injection control method, and executing oil injection action;
and 4, step 4: generating an ignition timing signal according to the ignition advance angle, and executing an ignition action;
and 5: fault diagnosis of the exhaust system is carried out, fault causes are positioned and an alarm is given,
in the step 2, an engine air input calculation model is established by using a slope-intercept method, the engine air input calculation model fits a function relation between the engine air input and the air input pressure of the pressure stabilizing cavity under the specific pressure stabilizing cavity air input temperature, the engine rotating speed and the throttle opening through test data, the engine air input is determined by using the engine air input calculation model through the air input pressure of the pressure stabilizing cavity,
wherein, the engine air input calculation model is as follows:
R＝(P manifold -P residualr )*K；
wherein R is engine intake air quantity, P manifold For maintaining the inlet pressure of the pressure chamber, P residualr The pressure of residual gas in a crankcase is related to the rotating speed and the mechanical characteristics of an engine, and K is a conversion factor of the air inlet pressure of a pressure stabilizing cavity and the relative air inflation quantity, and the method specifically comprises the following steps:
K＝K v *K t *K f *K p ；
wherein, K v A dimensionless parameter being the effective volume factor of the cylinder, the value of which depends on the mechanical properties of the engine, K p K is an intake flow loss coefficient, which is related to engine speed and mechanical characteristics t As a temperature correction factor, related to the inlet temperature of the plenum chamber, K f The nonlinear correction coefficient of the air inlet efficiency curve under the full-load working condition is related to the rotating speed, the load and the mechanical characteristics of the engine.
2. The fault diagnosis method according to claim 1, wherein in the step 1, the preliminary diagnosis includes:
electric appliance level diagnosis: detecting through a short power supply, a short ground and an open circuit method;
and (3) rationality diagnosis: and judging whether the received data is in a reasonable range of signals of each sensor under each working condition of the engine through a bench test.
3. The fault diagnosis method according to claim 1, wherein the step 2 specifically includes:
step 21: the method comprises the following steps that an engine maintains a certain rotating speed, the opening of a throttle valve is adjusted, the air inlet temperature of a pressure stabilizing cavity is maintained within a certain range, the air inlet amount of the engine is measured through an air flow meter, and the air inlet temperature and the air inlet pressure of the pressure stabilizing cavity in the pressure stabilizing cavity are measured through a temperature and pressure sensor;
step 22: performing data fitting by a regression analysis method, and calculating P under the current inlet air temperature of the pressure stabilizing cavity residualr And K;
step 23: maintaining the inlet air temperature of the current pressure stabilizing cavity unchanged, changing the rotating speed of the engine, and calculating P under different rotating speeds of the engine and different opening degrees of the throttle valve according to steps 21 and 22 residualr K, forming the opening of a throttle valve, the rotating speed of the engine and P under the air inlet temperature of the current pressure stabilizing cavity residualr And a three-dimensional table of throttle opening, engine speed and K, wherein the current engine speed and throttle opening are acquired, and P is obtained in an interpolation calculation mode residualr K, obtaining the air inflow of the engine according to the air inlet pressure of the pressure stabilizing cavity;
step 24: and (5) adjusting the air inlet temperature of the pressure stabilizing cavity, and repeating the steps 21 to 23 to obtain a coefficient table look-up table under different air inlet temperatures of the pressure stabilizing cavity.
4. The fault diagnosis method according to claim 1, wherein in step 3, the fuel injection pulse width is preset by using the air intake amount of the engine according to the bench test data by a self-learning method, the fuel injection pulse width is corrected again by feeding back the air-fuel ratio signals under different working conditions during operation, so that the air-fuel ratio is stabilized near the target value, and the fuel injection action is executed.
5. The fault diagnosis method according to claim 4, wherein the step 3 specifically includes:
step 31: the method comprises the following steps that an oil injection pulse width distribution map of basic oil injection obtained through a bench calibration test and corrected oil injection pulse width distribution maps of cylinder temperature, atmospheric pressure and pressure stabilizing cavity air inlet temperature are stored in a table form, an electronic control unit calculates a first oil injection pulse width through table lookup interpolation according to real-time engine rotating speed and throttle opening value, and correction is carried out through the cylinder temperature, the atmospheric pressure and the pressure stabilizing cavity air inlet temperature;
step 32: determining target air-fuel ratios under different working conditions, calculating the required oil quantity by using the engine air inflow and the target air-fuel ratio which are calculated by the engine air inflow calculation model, and calculating a second oil injection pulse width according to the characteristics of the oil injector;
step 33: carrying out weighted average on the first oil injection pulse width and the second oil injection pulse width obtained in the steps 31 and 32 to obtain a preset oil injection pulse width;
step 34: and according to the difference value between the current air-fuel ratio signal and the target air-fuel ratio, correcting the preset oil injection pulse width by adopting a proportional-integral-derivative control algorithm to obtain the final oil injection pulse width, and executing the oil injection action.
6. The fault diagnosis method according to claim 1, wherein the step 5 specifically includes:
step 51: through a plurality of test tests, typical fault types in the running process of the engine are summarized, corresponding relations are established between abnormal data and fault cases, and a data table is formed and stored in an electronic control unit;
step 52: when corresponding abnormal data occurs during the operation of the engine, the electronic control unit compares the abnormal data with the past abnormal data in the data table, judges the fault type and uploads a fault code for warning.
7. A control system for an aviation piston two-stroke supercharged engine, the control system performing fault diagnosis based on the method of any one of claims 1 to 6, the control system comprising:
the electronic control unit is used for monitoring sensor signals, performing functional diagnosis and sending instructions to the actuator;
a plurality of sensors, comprising: the system comprises a cylinder temperature sensor, a temperature exhaust sensor, a crankshaft position signal sensor, an air inlet temperature/pressure sensor, a throttle valve position sensor, an oil pressure sensor and a wide-area oxygen sensor, wherein the cylinder temperature sensor, the temperature exhaust sensor, the crankshaft position signal sensor, the air inlet temperature/pressure sensor, the throttle valve position sensor, the oil pressure sensor and the wide-area oxygen sensor are used for sensing data signals;
and the actuator comprises an oil injector, an ignition coil and a throttle valve and is used for executing corresponding operations according to the instructions of the electronic control unit.
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| CN113482767B (en) * | 2021-05-26 | 2022-08-09 | 珠海天晴航空航天科技有限公司 | Unmanned aerial vehicle and engine control method thereof |
| CN113464290B (en) * | 2021-06-28 | 2023-08-11 | 航天时代飞鸿技术有限公司 | Aviation piston engine supercharging self-adaptive control method and system |
| CN113250810B (en) * | 2021-06-29 | 2021-10-01 | 四川迅联达智能科技有限公司 | Method and system for stabilizing intake pressure of two-stroke engine |
| CN113738526A (en) * | 2021-09-18 | 2021-12-03 | 北京信息科技大学 | Fault diagnosis system for abnormal oil injection of small aviation piston engine |
| CN114544181A (en) * | 2022-01-27 | 2022-05-27 | 南京航空航天大学 | Calibration system and control method for electronic control aviation two-stroke kerosene engine |
| CN114508435A (en) * | 2022-02-17 | 2022-05-17 | 上海东古智能科技有限公司 | Control system of two-stroke gasoline aircraft engine |
| CN114720133B (en) * | 2022-04-19 | 2024-06-18 | 潍柴动力股份有限公司 | Calibration method and calibration system for air-fuel ratio of high-power gas engine |
| CN115247606A (en) * | 2022-04-29 | 2022-10-28 | 长城汽车股份有限公司 | Engine fault processing method, control equipment and storage medium |
| CN115111078B (en) * | 2022-07-22 | 2024-03-19 | 浙江吉利控股集团有限公司 | Engine torque monitoring method, equipment and storage medium |
| CN118532278B (en) * | 2024-07-15 | 2024-10-01 | 西北工业大学 | Engine fuel supply curve calibration system, method, device and electronic equipment |
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