CN116754243A - Engine fault integrated discrimination method based on multi-level progressive detection principle - Google Patents
Engine fault integrated discrimination method based on multi-level progressive detection principle Download PDFInfo
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Abstract
The application discloses an engine fault diagnosis method based on a multi-level progressive detection principle, which is characterized by comprising the following steps of: measuring the geometric deviation angle of the engine timing to finish the detection of a mechanical layer; measuring and correcting Hall pulse signals of the engine crankshaft and the camshaft to finish detection of an electric signal angle layer: comprehensive analysis of crank angle domain/frequency domain of cold test speed-up working condition of engine, namely vibration acceleration layer detection: artificial intelligence fault identification based on big data. The method provided by the application can progressively judge and identify the faults through the mechanical layer, the electric signal angle layer, the timing belt tension or vibration frequency and the vibration acceleration layer respectively, so that common faults of the engine in the processes of engine cold test and bench test can be rapidly identified. In the judgment of the vibration acceleration layer, the mechanical layer and the electric signal angle layer are combined, and the engine fault is rapidly identified and predicted through an artificial intelligent fault judgment algorithm based on big data.
Description
Technical Field
The application relates to an integrated judging method for engine faults, which relates to an automobile engine timing measurement technology, an engine cold test technology, NVH analysis (vibration acceleration-crank shaft angular domain relation and vibration acceleration-crank shaft rotating speed), an artificial intelligent integrated judging method, an engine bench test technology and the like.
Background
The common engine fault diagnosis at the present stage, in particular NVH fault diagnosis, mainly comprises two kinds of methods, namely a steady-state vibration acceleration-crankshaft rotation speed method and a steady-state vibration acceleration-crankshaft rotation angle method. Under normal conditions, the two can feed back the order of the engine faults and the parts corresponding to the fault characteristics respectively. At this stage, however, the two analysis methods are typically used independently for determining engine failure. Meanwhile, the fault form judgment generally depends on manual subjective judgment, and a layer-by-layer stacking phenomenon exists in mutual inspection among layers (such as deviation of mechanical installation can cause deviation of electrical appliance detection).
In addition, under the condition of performing fault diagnosis of a steady-state vibration acceleration-crank angle method, the engine at the present stage generally has two methods for collecting angular fields, namely a direct installation angle standard method or a crank Hall sensor collecting method.
The direct-mounting angle marker method refers to that the angle marker is mounted on a crankshaft belt pulley at the front end of an engine before testing, and the method can directly obtain good crank angle domain signals because the angle marker has higher measurement accuracy. However, since the corner marker needs to be independently installed at the front end of the engine through a tool, the installation process and the centering process of the corner marker have very high positioning precision requirements, and various installation errors are easy to introduce. Meanwhile, in the running process of the engine, the rigidity of the bracket of the angle marker is low, and a series of conditions such as torsion and the like are unavoidable, so that the dynamic acquisition characteristic of the angle marker is influenced.
The crankshaft Hall sensor acquisition method is to subdivide the signals of the crankshaft Hall sensors of the engine to obtain angular domain signals. The method has the advantages of no need of adding a sensor and good economical efficiency. However, since the crank position sensor mounting plate has a certain component mounting error and machining tolerance in the press-fitting process, the deviation is difficult to eliminate in the collection of the introduction angle area, and a special calibration means and a special calibration method are required to be provided. In particular, NVH fault diagnosis often occurs, and the angular domain signal and the spectrum analysis corresponding to the vibration moment are not actually occurring areas.
Disclosure of Invention
The purpose of the application is that: and the common faults of the engine in the cold test and bench test processes of the engine are rapidly identified.
In order to achieve the above purpose, the technical scheme of the application is to provide an engine fault diagnosis method based on a multi-level progressive detection principle, which is characterized by comprising the following steps:
step 1, measuring a geometric deviation angle of engine timing to finish mechanical layer detection:
measuring the timing geometric angles of a crankshaft and an intake camshaft and an exhaust camshaft of the tested engine through an engine timing angle measuring instrument respectively, and calculating to obtain a timing geometric deviation angle value based on part machining tolerance information related to timing;
step 2, if the geometric deviation angle value of the timing obtained in the step 1 exceeds the allowable range of the timing deviation, indicating that the timing angle is out of tolerance, manually intervening for repairing, reassembling and adjusting the timing, and returning to the step 1 after repairing; if the geometric deviation angle value of the timing obtained in the step 1 does not exceed the allowable range of the timing deviation, entering the next step; thus, the calibration of the actual measured top dead center and the theoretical top dead center is completed while the timing geometric angle of the engine timing mechanical system is measured;
step 3, measuring and correcting Hall pulse signals of an engine crankshaft and a camshaft to finish detection of an electric signal angle layer:
under the constant-speed towing condition, output signals of a crankshaft position sensor and an intake camshaft position sensor and an exhaust camshaft position sensor are respectively collected, so that Hall pulse signals of an engine crankshaft and a camshaft are measured, whether a positive effective angle output by the Hall sensor meets the requirement or not is judged, wherein the positive effective angle comprises a positive geometric deviation angle and a Hall sensor system error, and correction from a mechanical layer to an electric signal angle layer of the engine timing angle deviation is completed;
step 4, comprehensively analyzing the crank angle domain/frequency domain of the cold test speed-up working condition of the engine, namely detecting a vibration acceleration layer:
under a preset speed-up working condition, signals output by a vibration acceleration sensor and a crankshaft position sensor which are arranged on the cylinder body are respectively collected through a vibration analyzer; then, the rotational speed-acceleration frequency domain relation of the engine under the condition of increasing speed is obtained by combining the rotational speed of the crankshaft, the acceleration value of each order is calculated, and the acceleration frequency domain contribution quantity of each order is identified; meanwhile, by combining the relation between the crank shaft angle domain and the acceleration time domain, characteristic acceleration contribution of each cylinder is identified according to order analysis, whether the vibration acceleration of the engine meets the design requirement is judged, and if the vibration acceleration characteristics of the tested engine are exceeded, step 5 is carried out;
step 5, artificial intelligence fault identification based on big data:
filtering the vibration acceleration data acquired in the step 4, so as to filter background noise signals introduced by the outside; then capturing the characteristics of the fault acceleration signals; the failure mode is then identified and classified using a big data based artificial intelligence failure recognition algorithm to determine the failure mode and complete the preliminary localization of the failed component.
Preferably, in step 1, the machining tolerance of the part related to the timing is obtained by scanning a two-dimensional code on the tested engine.
Preferably, the step 1 further comprises the steps of:
step 101, mounting an engine timing angle measuring instrument to the rear end of a tested engine, and respectively connecting with a crankshaft and a positioning clamping groove at the tail end of an intake camshaft and an exhaust camshaft;
step 102, dragging and rotating the crankshaft of the tested engine at a low speed by using a special motor for cold test, so that more than two working cycles are completed. Measuring the timing geometric angle of the engine to be measured by utilizing the sensing characteristic of a capacitive acceleration sensor of the engine timing angle measuring instrument to the gravity direction;
and 103, scanning machining tolerance information of the timing related parts on the two-dimensional code of the parts by using a scanning gun, acquiring the information, and automatically calculating and generating the timing geometric deviation angle value by using software.
Preferably, the step 3 further comprises the steps of:
step 301, detecting vibration frequencies of a timing belt at a tensioning wheel end and an idler wheel end by using a laser frequency meter to obtain vibration frequency T of the tensioning wheel end 1 With the idler end vibration frequency T 2 Judging the vibration frequency T of the tensioning wheel end 1 With the idler end vibration frequency T 2 Whether the value range shown in the following formula is satisfied:
f zd1 ≤T 1 ≤f zd2 、f dd1 ≤T 2 ≤f dd2
wherein f zd1 、f dd1 F is a preset lower limit value zd2 、f dd2 Is a preset upper limit value;
if the value range is met, the tension or vibration frequency T of the timing belt is assigned as qualified, and the step 302 is entered;
if the value range is met, the tensioning force or the vibration frequency T of the timing belt is assigned as unqualified, the effective angle H at the time is judged to be unqualified, the fact that the fault of the timing system needs to be manually checked and repaired is explained, and the step 1 is returned after the checking and repairing;
302, if the timing geometrical deviation angle G is qualified, namely the timing geometrical angle F is qualified, entering a Hall sensor system error C judging flow, wherein the timing geometrical deviation angle G is measured and obtained, and the timing geometrical deviation angle G is respectively three reference values and three tolerances of an Intake camshaft geometrical deviation angle G-Intake, an exhaust camshaft geometrical deviation angle G-exhaust and a crankshaft geometrical deviation angle G-crankshift, and Intake initial 、Exhaust initial The initial values of the timing angles of the intake camshaft and the exhaust camshaft are respectively shown as follows:
G～Intake＝Intake initial ℃a
g Intake low ℃a≤G～intake≤g Intake up ℃a
G～Exhaust＝Exhaust initial ℃a
g exhaust low ℃a≤G～exhaust≤ge xhaust up ℃a
G～crankshaft＝0℃r
g crankshaft low ℃r≤G～crankshaft≤g Crankshaft up ℃r
g Intake low 、g Intake up the upper limit and the lower limit of the tolerance of the geometric deviation angle G-intake reference value of the intake camshaft are adopted; g exhaust low 、ge xhaust up The upper limit and the lower limit of the tolerance of the geometric deviation angle G-exhaust reference value of the row camshaft are adopted; g crankshaft low 、g Crankshaft up Is the geometric deviation angle G of the crankshaft to the upper extent C An upper tolerance limit and a lower tolerance limit for the rankshaft criterion; DEG C r represents the angle by which the crankshaft rotates about the center of rotation; DEG C a represents the angle by which the camshaft rotates about the center of rotation;
if the geometric deviation angle G exceeds the range shown by the judgment standard, judging that the geometric deviation angle G is unqualified, indicating that the geometric deviation angle G is out of tolerance, requiring manual intervention for repairing, reassembling and adjusting the timing, and returning to the step 1 after repairing; if the geometric deviation angle G does not exceed the range shown by the judgment standard, judging that the geometric deviation angle G is qualified;
step 303, entering a judging flow of a Hall sensor system error C, wherein the Hall sensor system error C comprises three values of an effective deviation angle E-intake of an intake camshaft and an effective deviation angle E-exhaust of a row camshaft and an effective deviation angle E-crankshaft of a crankshaft, and the judging standard is as follows:
C＝＝E～intake
E～intake＝H-(G～intake)-(M～Intake)
d intake low ≤E～intake≤d intake up
wherein d intake low And d intake up Respectively representing the upper and lower limits of the allowable maximum relative deviation angle of the intake camshaft; M-Intake is taken as feedMachining tolerance of the air cam shaft;
C＝＝E～exhaust
E～exhaust＝H-(G～exhaust)-(M～Exhaust)
d exhaust low ≤E～Exhaust≤d exhaust up
wherein d exhaust up And d exhaust low Respectively representing the upper and lower limits of the allowable maximum relative deviation angle of the exhaust camshaft; M-Exhaust represent Exhaust camshaft machining tolerances;
C＝＝E～crankshaft
E～crankshaft＝H-(G～crankshaft)-(M～Crankshaft)
d crankshaft low ≤E～Exhaust≤d crankshaft up
wherein d crankshaft up And d crankshaft low Respectively representing the upper and lower limits of the maximum allowable relative deviation angle of the crankshaft; M-Crankshaft represents Crankshaft machining tolerance;
when the system error C of the Hall sensor exceeds the value range according to the judging standard, judging that the positive effective angle H is unqualified, indicating that the fault of the timing system needs to be manually intervened for repairing, and returning to the step 1 after repairing; and if the system error C of the Hall sensor does not exceed the value range, judging that the positive effective angle H is qualified.
Preferably, in step 4, the crank angular domain relationship is a vibration acceleration-crank angular domain relationship; the acceleration time domain relationship is vibration acceleration-crankshaft rotational speed.
Preferably, the contribution of the vibration of the reciprocating linear motion type parts of each cylinder to the vibration acceleration can be rapidly identified through the analysis of the vibration acceleration-crank angle domain.
The method provided by the application can be used for progressively judging and identifying the faults through the mechanical layer (part machining tolerance, part assembly error), the electric signal angle layer (sensor system error), the tension force or vibration frequency of the timing belt and the vibration acceleration layer, so that common faults of the engine in the processes of cold test and bench test of the engine can be rapidly identified. In the judgment of the vibration acceleration layer, the mechanical layer and the electric signal angle layer are combined, and the engine fault is rapidly identified and predicted through an artificial intelligent fault judgment algorithm based on big data.
Drawings
FIG. 1 illustrates various links of engine timing misalignment including mechanical and electrical signal angle layers;
FIG. 2 illustrates a typical engine cold test order map;
FIG. 3 illustrates a typical engine crank angle domain map;
FIG. 4 illustrates an artificial intelligence algorithm such as a neural network;
FIG. 5 illustrates a confusion matrix for a test set of a fault diagnosis model of a support vector machine at different rotational speeds;
FIG. 6 is a flow chart of an engine fault integration operation of the multi-level progressive inspection principle.
Detailed Description
The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. Furthermore, it should be understood that various changes and modifications can be made by one skilled in the art after reading the teachings of the present application, and such equivalents are intended to fall within the scope of the application as defined in the appended claims.
The application discloses an engine fault diagnosis method based on a multi-level progressive detection principle, which comprises the following steps:
step 1, measuring the geometric deviation angle of engine timing
The engine timing geometrical deviation angle is determined as the identification of the mechanical layer state of the engine, and the basic flow further comprises the following steps:
and 101, mounting an engine timing angle measuring instrument T220 (the instrument resolution is 0.01 ℃ r, hereinafter referred to as T220) at the rear end of the tested engine, and respectively connecting with the crankshaft and the tail end positioning clamping grooves of the air intake and exhaust cam shaft.
Step 102, dragging and rotating the crankshaft of the tested engine at a low speed by using a special motor for cold test, so that more than two working cycles are completed. And measuring the geometric angle of the timing of the tested engine by using the sensing characteristic of the T220 acceleration sensor on the gravity direction.
And 103, scanning machining tolerance information of timing related parts on the two-dimensional code of the parts by using a scanning gun, automatically calculating and generating a timing geometric deviation angle value by software (C#) after acquiring the information, and completing calibration work of a theoretical top dead center and a geometric top dead center of a mechanical layer.
Step 2, if the geometric deviation angle value of the timing exceeds the allowable range of the timing deviation, the fact that the timing angle is out of tolerance is indicated, manual intervention is needed for repairing (reassembling and timing adjustment), and after repairing, the step 1 is returned to continue measuring;
if the timing geometry deviation angle value does not exceed the range allowed by the timing deviation, then the T220 is detached from the tested engine and ready for the next step.
Step 3, measuring and correcting Hall pulse signals of an engine crankshaft and a camshaft, namely, measuring and correcting a positive effective angle, wherein the positive effective angle is measured and corrected into an electric signal angle layer detection, and the process comprises the following steps:
after a test accessory is preassembled on a tested engine, the tested engine is automatically sent to a cold test station by utilizing a sliding rail, a cold test bench is started, the tested engine starts to be dragged and rotated at a constant speed according to a preset rotating speed spectrum, output signals of a crankshaft position sensor and an intake camshaft position sensor and an exhaust camshaft position sensor are respectively collected, hall pulse signals of a crankshaft and a camshaft are measured, namely a positive effective angle, and the positive effective angle comprises a sensor system error (mainly comprising a sensor installation deviation).
Considering that the camshaft of the engine and the Hall signal hardware part of the crankshaft consist of parts such as a signal wheel, a sensor, a flange and the like and are screwed by bolts, various deviations are inevitably generated when the engine is processed and assembled, and the interferences of equipment and human factors such as part processing tolerance, part assembly error, hall sensor installation deviation and the like are included. In order to effectively separate the deviation generated by each layer, the application defines the relative parameters of the engine timing as follows:
(1) The DEG C r represents the rotation angle of the crankshaft around the rotation center, namely the crank angle, which is simply called as the crank angle, one working cycle of the engine, the crank angle is 720 ℃ r, and the relation between the crank angle and the cam shaft angle is 2:1.
(2) The temperature of the cam shaft is expressed as a rotation angle of the cam shaft around a rotation center, the cam shaft is called a cam shaft rotation angle for short, one working cycle of the engine, the cam shaft rotation angle is 360 ℃ a, and the relation between the cam shaft rotation angle and the crank shaft rotation angle is 1:2.
(3) Part machining tolerance a: is a machining tolerance of parts related to timing, including dimensional tolerance and form and position tolerance.
(4) Two-dimensional code information: the parameter belongs to timing related parts and comprises part machining tolerances of an Intake camshaft, an Exhaust camshaft and a Crankshaft, wherein the machining tolerance of the Intake camshaft is represented as M-Intake, the machining tolerance of the Exhaust camshaft is represented as M-Exhaust, and the machining tolerance of the Crankshaft is represented as M-Crankshaft. The machining tolerance information is in a two-dimensional code form and follows the engine.
(5) Part assembly error B: the difference between the installation position of the parts and the ideal position required by the design and specification of the assembly specification and the process mainly comprises part errors, tool equipment errors, operation errors, environmental errors and consciousness errors.
(6) Sensor system error C: the error of the sensor system error C is the difference between the measured value and the actual value, and the sensor system error C comprises application error (installation error), insertion error, characteristic error, dynamic error and environmental error.
(7) Theoretical top dead center TDC (Top Dead Center): is the extreme position of the piston top furthest from the crankshaft center of rotation. The parameter is a theoretical value, and various deviations and errors are included in actual production processing and measurement. The theoretical top dead center TDC is 0deg.C r.
(8) Geometric top dead center D: the parameter belongs to the category of a mechanical layer, is a top dead center actually measured after the engine is assembled by a mechanical measuring instrument T220, and comprises a part machining deviation A and a part assembly error B. The calculation formula of the geometric top dead center D is as follows:
d=tdc+ (a+b) or d=a+b
The acquisition of the included angle between the TDC and the corresponding position is performed through a T220 device (refer to patent numbers of the T220 device: CN201811141194.1, CN201811142869.4, CN201821592505.1 and CN 201821592508.5), the measurement principle is that the displacement, namely the angle through which the crankshaft rotates, is measured and calculated according to a capacitive acceleration sensor, and the TDC is defined as 0 ℃ r:
(9) Effective top dead center E: the parameter belongs to the category of an electric signal angle layer, is a top dead center obtained by collecting Hall pulse signals of a crankshaft/intake and exhaust camshaft sensor and calculating the phase relation of the crankshaft/intake and exhaust camshaft, and comprises a Hall sensor system error C (mainly comprising sensor installation deviation). The calculation formula of the effective top dead center E is as follows: e=f+c or e= (a+b+c).
(10) Timing belt tension or vibration frequency T: utilize laser frequency meter to take-up pulley end vibration frequency T 1 With the idler end vibration frequency T 2 Detecting the vibration frequency of the timing belt so as to obtain the vibration frequency of the front end crankshaft of the engine, which is assembled by the tensioning wheel, the idler wheel and the timing belt, wherein the judgment standard is that the vibration frequency range of the tensioning wheel end is f zd1 ～f zd2 Hz and idler end vibration frequency range f dd1 ～f dd2 Hz, i.e. f zd1 ≤T 1 ≤f zd2 、f dd1 ≤T 2 ≤f dd2 . T is a logic judgment value, and the vibration frequency T of the tensioning wheel end 1 With the idler end vibration frequency T 2 And when the value range is met, the tensioning force or the vibration frequency T of the timing belt is assigned to be qualified, and when the value range is not met, the value is assigned to be unqualified.
(11) Timing geometry angle F: the parameter belongs to the category of a mechanical layer, is a timing angle which is actually measured after the engine is assembled by using a mechanical measuring instrument, and generally has part machining tolerance and part assembly error inevitably. The deviation of the actual measured geometric top dead center from the theoretical top dead center is a positive geometric deviation angle G, which comprises the following steps: f=tdc+ (a+b) or f=a+b.
(12) Timing geometrical deviation angle G:
G＝∣TDC-F∣
∴F＝TDC+(A+B)；
∵G＝A+B；
the parameters are obtained by actual measurement, wherein the timing geometrical deviation angle G is respectively three reference values and three tolerances of an Intake camshaft geometrical deviation angle G-Intake, an exhaust camshaft geometrical deviation angle G-exhaust and a Crankshaft geometrical deviation angle G-Crankshaft, intake initial 、Exhaust initial The initial values of the timing angles of the intake camshaft and the exhaust camshaft are respectively shown as follows:
G～Intake＝Intake initial ℃a
g Intake low ℃a≤G～Intake≤g Intake up ℃a
G～Exhaust＝Exhaust initial ℃a
g exhaust low ℃a≤G～Exhaust≤ge xhaust up ℃a
G～Crankshaft＝0℃r
g crankshaft low ℃r≤G～Crankshaft≤g Crankshaft up ℃r
if the above range is exceeded, the timing geometrical deviation angle G is unqualified, which means that the timing angle is out of tolerance, and manual intervention for repair (reassembly and timing adjustment) is required.
Because there is always an error (new error introduced) between the engine components after assembly. Meanwhile, the G-Crankshaft engine installed on line cannot be guaranteed to be a theoretical zero point under the normal condition. It is necessary to introduce this flow of out-of-tolerance judgment.
(13) The positive effective angle H: the parameter belongs to the category of an electric signal angle layer, and is a pulse signal of a crankshaft and a camshaft Hall of an engine is collected and measured by using a special instrument, and the positive effective angle comprises the deviation and the error.
(14) The formula of the positive effective angle H algorithm is shown as follows:
(F+C)and T→H
F＝A+B
(A+B+C)and T→H
(A+B+C)＝＝X
X and T→H
the method comprises the following steps:
step 301, judging the vibration frequency T of the tensioning wheel end 1 With the idler end vibration frequency T 2 Whether the value range shown in the following formula is satisfied:
f zd1 ≤T 1 ≤f zd2 、f dd1 ≤T 2 ≤f dd2
wherein f zd1 、f dd1 F is a preset lower limit value zd2 、f dd2 Is a preset upper limit value.
If the value range is met, the tensioning force or the vibration frequency T of the timing belt is assigned to be qualified, and an F+C judgment flow is entered, wherein F is a timing geometric angle, and C is a Hall sensor system error.
Step 302, according to the formula g=f= (a+b), the G value and the F value are the relationship between the angular quantity and the linear quantity, if the timing geometric deviation angle G is qualified, the timing geometric angle F is qualified, and the judgment flow of the hall sensor system error C is entered.
Step 303, hall sensor system error C (sensor installation error) belongs to the difference between the mechanical layer and the electrical signal angle layer. When the judging flow of the Hall sensor system error C is entered, the timing geometrical deviation angle G is judged to be a qualified value, and meanwhile, the Hall sensor system error C is a value which needs to be corrected relative to the timing geometrical deviation angle G. The Hall sensor system error C comprises three values of an effective deviation angle E-intake of an air inlet cam shaft, an effective deviation angle E-exhaust of a row cam shaft and an effective deviation angle E-crankshaft of a crank shaft, and the judgment standard is as follows:
C＝＝E～intake
E～intake＝H-(G～Intake)-(M～Intake)
d intake low ≤E～Intake≤d intake up
wherein d intake low And d intake up Respectively representing the upper and lower limits of the allowable maximum relative deviation angle of the intake camshaft;
C＝＝E～exhaust
E～exhaust＝H-(G～exhaust)-(M～exhaust)
d exhaust low ≤E～Exhaust≤d exhaust up
wherein d exhaust up And d exhaust low Respectively represent the upper and lower limits of the allowable maximum relative deviation angle of the exhaust camshaft.
C＝＝E～crankshaft
E～crankshaft＝H-(G～crankshaft)-(M～crankshaft)
d crankshaft low ≤E～Exhaust≤d crankshaft up
Wherein d crankshaft up And d crankshaft low Representing the upper and lower limits of the allowable maximum relative offset angle of the crankshaft, respectively.
When the system error C of the Hall sensor exceeds the value range according to the judging standard, the positive effective angle H-disqualification is judged according to the formula (F+C) and T-H, and the fact that the fault of the timing system needs manual intervention for repair is explained.
If the timing belt tensioning force or vibration frequency T is disqualified, the timing effective angle H is judged to be disqualified, and the fact that the timing system fault needs to be checked and repaired manually is explained.
Step 4, comprehensive analysis of crank angle domain/frequency domain of engine cold test speed-up working condition, namely vibration acceleration layer detection
And 3, after the uniform dragging rotation in the step is completed, the cold test bench drags and rotates the tested engine according to a preset speed-up working condition. Meanwhile, the vibration analyzer respectively collects a vibration acceleration sensor and a crankshaft position sensor which are arranged on the cylinder body. And then, a method such as fast Fourier transform is used for acquiring a rotational speed-acceleration frequency domain relation (spectrogram) under the engine speed-increasing working condition by combining the rotational speed of the crankshaft, the acceleration value of each order is calculated, and the acceleration frequency domain contribution quantity of each order is identified. Meanwhile, the characteristic acceleration contribution quantity of each cylinder is identified according to order analysis by combining the relation between the crank shaft angle domain and the acceleration time domain. And judging whether the vibration acceleration of the engine meets the design requirement.
As shown in the analysis of the crank angle domain of fig. 3, 0 ℃ r is the effective top dead center of each cylinder, the angular resolution is 0.5 ℃ r, the self-adaptive dimension of the amplitude is + -5 m/s2, and the vibration signal is analyzed after corresponding to the crank rotation angle of 0-720 ℃ r (angle domain), namely one working cycle of the engine.
Step 5, artificial intelligent fault identification based on big data
After the judgment of the steps 1 to 4 is completed, if the vibration acceleration characteristic of the tested engine exceeds the limit, the step is entered.
In this step, the acceleration signal acquired by the acceleration sensor may include signal noise introduced by external interference or EMC interference with a high probability. Firstly, the vibration acceleration data acquired in the step 4 needs to be filtered, so that background noise signals introduced by the outside are filtered. Features of the fault acceleration signal (such as the order of the vibration acceleration contributions and the corresponding angular domain, etc.) are then captured. The fault pattern is then identified and classified using an artificial intelligence algorithm such as a neural network as shown in fig. 4 or a confusion matrix of a test set at different rotational speeds as shown in fig. 5 for a fault diagnosis model of a support vector machine, etc., thereby determining a fault form and completing preliminary localization of a fault element.
One specific implementation method of the technical content comprises the following steps of
1. Mounting an engine pre-detection and angle measurement instrument T220;
in this step, the engine to be tested is first mounted on a process tray, and its appearance and accessories are visually inspected to see whether or not there are abnormal phenomena such as defects of parts or leakage of lubricating oil. And then, respectively installing T220 timing angle measuring instruments at the rear ends of the crankshaft and the intake and exhaust camshafts.
2. Scanning a two-dimensional code of an engine part, and reading part machining tolerance information;
in this step, the engine component dimensional tolerance information relating to the timing processed in the machining stage is scanned by a scanning gun and automatically input into a computer.
The special station of the engine cold test bench completes T220 measurement and timing geometric angle measurement/calculation of the timing geometric deviation angle (geometric top dead center) and correction;
in the step, a motor special for cold test T220 is used for dragging the bolt of the front end shaft head of the engine, a lower rotating speed (< 30 Rpm) is used for dragging and rotating the crankshaft of the engine, more than two complete working cycles are completed, and the timing geometric angles (including part assembly errors) are collected and automatically input into a computer. Then, the computer automatically calculates the geometric deviation angle (geometric top dead center) of the timing according to the part machining tolerance information scanned in the previous step according to G=F- (A+B), wherein the geometric top dead center is corrected once for the theoretical top dead center, and the step means that the geometric top dead center after the mechanical layer correction is infinitely close to the theoretical top dead center. And removing the instrument after the measurement is finished, and simultaneously, finishing the pre-detection and cold test preparation work of the detected engine, and preparing for entering the next step.
3. Constant-speed dragging and rotating and Hall pulse signal acquisition of crankshaft and camshaft
And (3) operating the prepared engine tray to a cold test rack, finishing the fixing of the tray and the connecting shaft work of the process flywheel, then starting the rack, and dragging and rotating the engine under a preset uniform speed working condition. By collecting the engine crankshaft and Hall pulse signals, namely the timing effective angle, under the constant-speed working condition, a computer calculates and corrects the deviation between the engine crankshaft and the Hall pulse signals, namely the Hall sensor system error (crankshaft position sensor installation error), and the timing geometric angle (geometric top dead center) according to a preset algorithm (F+C) and T-H, and recognizes whether the deviation meets the tolerance requirement, if the deviation meets the requirement, the engine timing deviation angle is corrected for the second time, namely the timing geometric angle, the timing effective angle or the geometric top dead center and the effective top dead center are infinitely close to the theoretical top dead center. And (3) completing the calibration work of the engine timing angle deviation from a mechanical layer to an electric signal angle layer.
4. Engine timing belt tension (vibration frequency) measurement and determination
In the step, when the cold test machine drags the engine to run, the laser frequency meter is utilized to detect the vibration frequency of the timing belt at the tensioning wheel end and the idler wheel end, so that the vibration frequency of the assembled connecting part of the crankshaft at the front end of the engine and the camshaft, comprising the tensioning wheel, the idler wheel and the timing belt, is obtained. The judgment standard is the vibration frequency T of the end of the timing belt tensioning wheel 1 A tensioning wheel end and a T2 idler wheel end, wherein f zd1 ≤T 1 ≤f zd2 、f dd1 ≤T 2 ≤f dd2 When the engine timing angle exceeds the range, the engine timing angle is deviated or the potential risks such as tooth jump and the like tend to occur, and at the moment, the engine should be stopped immediately to check whether the front end tensioning wheel, the idler wheel and the timing belt assembly meet the process requirements, in particular whether the mounting process of the tensioning force and the parts meet the quality requirements. The detection item can rapidly judge whether the tensioning force of the tensioning wheel at the connecting part of the crankshaft and the camshaft, the concentricity (circular runout) of the idler wheel and the material performance of the timing toothed belt meet the process requirements.
5. Comprehensive analysis of vibration acceleration angular domain/frequency domain of cold test speed-up working condition of engine
After the constant-speed dragging working condition of the engine is completed, the cold test bench is set to speed up and drag according to the preset working condition, and meanwhile, a vibration analyzer is used for collecting signals of a crankshaft position sensor, a cylinder cover and a cylinder body acceleration sensor. Subsequently, the vibration acceleration-crank angular domain relationship (time domain analysis) and the vibration acceleration-crank rotational speed (frequency domain waterfall diagram analysis) are identified, respectively. And calculating the frequency domain contribution of the acceleration of each order of the engine and the contribution of the acceleration of each cylinder respectively, and judging whether the vibration acceleration of the engine meets the qualification standard. Subsequently, the engine disassembly line speed for the cold test is completed and the cold test bench is disengaged.
6. Engine cold test fault identification and judgment
And when the engine has faults such as overrun of vibration acceleration or abnormal vibration order in the cold test process, entering an engine cold test fault identification and judgment process.
In this step, the acceleration signal acquired by the acceleration sensor may include signal noise introduced by external interference or EMC interference with a high probability. Firstly, the vibration acceleration data acquired in the third step is required to be filtered, so that background noise signals introduced by the outside are filtered. Features of the fault acceleration signal (such as the order of the vibration acceleration contributions and the corresponding angular domain, etc.) are then captured.
The failure mode is then identified and classified using artificial intelligence algorithms (e.g., neural networks or support vector machines, etc.), thereby determining the failure mode and completing the preliminary localization of the failed component.
Claims (6)
1. An engine fault diagnosis method based on a multi-level progressive detection principle is characterized by comprising the following steps:
step 1, measuring a geometric deviation angle of engine timing to finish mechanical layer detection:
measuring the timing geometric angles of a crankshaft and an intake camshaft and an exhaust camshaft of the tested engine through an engine timing angle measuring instrument respectively, and calculating to obtain a timing geometric deviation angle value based on part machining tolerance information related to timing;
step 2, if the geometric deviation angle value of the timing obtained in the step 1 exceeds the allowable range of the timing deviation, indicating that the timing angle is out of tolerance, manually intervening for repairing, reassembling and adjusting the timing, and returning to the step 1 after repairing; if the geometric deviation angle value of the timing obtained in the step 1 does not exceed the allowable range of the timing deviation, entering the next step; thus, the calibration of the actual measured top dead center and the theoretical top dead center is completed while the timing geometric angle of the engine timing mechanical system is measured;
step 3, measuring and correcting Hall pulse signals of an engine crankshaft and a camshaft to finish detection of an electric signal angle layer:
under the constant-speed towing condition, output signals of a crankshaft position sensor and an intake camshaft position sensor and an exhaust camshaft position sensor are respectively collected, so that Hall pulse signals of an engine crankshaft and a camshaft are measured, whether a positive effective angle output by the Hall sensor meets the requirement or not is judged, wherein the positive effective angle comprises a positive geometric deviation angle and a Hall sensor system error, and correction from a mechanical layer to an electric signal angle layer of the engine timing angle deviation is completed;
step 4, comprehensively analyzing the crank angle domain/frequency domain of the cold test speed-up working condition of the engine, namely detecting a vibration acceleration layer:
under a preset speed-up working condition, signals output by a vibration acceleration sensor and a crankshaft position sensor which are arranged on the cylinder body are respectively collected through a vibration analyzer; then, the rotational speed-acceleration frequency domain relation of the engine under the condition of increasing speed is obtained by combining the rotational speed of the crankshaft, the acceleration value of each order is calculated, and the acceleration frequency domain contribution quantity of each order is identified; meanwhile, by combining the relation between the crank shaft angle domain and the acceleration time domain, characteristic acceleration contribution of each cylinder is identified according to order analysis, whether the vibration acceleration of the engine meets the design requirement is judged, and if the vibration acceleration characteristics of the tested engine are exceeded, step 5 is carried out;
step 5, artificial intelligence fault identification based on big data:
filtering the vibration acceleration data acquired in the step 4, so as to filter background noise signals introduced by the outside; then capturing the characteristics of the fault acceleration signals; the failure mode is then identified and classified using a big data based artificial intelligence failure recognition algorithm to determine the failure mode and complete the preliminary localization of the failed component.
2. The method for diagnosing engine faults based on the multi-level progressive detection principle as claimed in claim 1, wherein in the step 1, the machining tolerance of the parts related to the timing is obtained by scanning a two-dimensional code on the engine to be tested.
3. The method for diagnosing engine faults based on the multi-level progressive inspection principle as claimed in claim 1, wherein the step 1 further comprises the steps of:
step 101, mounting an engine timing angle measuring instrument to the rear end of a tested engine, and respectively connecting with a crankshaft and a positioning clamping groove at the tail end of an intake camshaft and an exhaust camshaft;
step 102, dragging and rotating the crankshaft of the tested engine at a low speed by using a special motor for cold test, so that more than two working cycles are completed. Measuring the timing geometric angle of the engine to be measured by utilizing the sensing characteristic of a capacitive acceleration sensor of the engine timing angle measuring instrument to the gravity direction;
and 103, scanning machining tolerance information of the timing related parts on the two-dimensional code of the parts by using a scanning gun, acquiring the information, and automatically calculating and generating the timing geometric deviation angle value by using software.
4. The method for diagnosing engine faults based on the multi-level progressive inspection principle as claimed in claim 1, wherein the step 3 further comprises the steps of:
step 301, detecting vibration frequencies of a timing belt at a tensioning wheel end and an idler wheel end by using a laser frequency meter to obtain vibration frequency T of the tensioning wheel end 1 With the idler end vibration frequency T 2 Judging the vibration frequency T of the tensioning wheel end 1 With the idler end vibration frequency T 2 Whether the value range shown in the following formula is satisfied:
f zd1 ≤T 1 ≤f zd2 、f dd1 ≤T 2 ≤f dd2
wherein f zd1 、f dd1 F is a preset lower limit value zd2 、f dd2 Is a preset upper limit value;
if the value range is met, the tension or vibration frequency T of the timing belt is assigned as qualified, and the step 302 is entered;
if the value range is met, the tensioning force or the vibration frequency T of the timing belt is assigned as unqualified, the effective angle H at the time is judged to be unqualified, the fact that the fault of the timing system needs to be manually checked and repaired is explained, and the step 1 is returned after the checking and repairing;
302, if the timing geometrical deviation angle G is qualified, namely the timing geometrical angle F is qualified, entering a Hall sensor system error C judging flow, wherein the timing geometrical deviation angle G is measured and obtained, and the timing geometrical deviation angle G is respectively three reference values and three tolerances of an Intake camshaft geometrical deviation angle G-Intake, an exhaust camshaft geometrical deviation angle G-exhaust and a crankshaft geometrical deviation angle G-crankshift, and Intake initial 、Exhaust initial The initial values of the timing angles of the intake camshaft and the exhaust camshaft are respectively shown as follows:
G～Intake＝Intake initial ℃a
g Intakelow ℃a≤G～intake≤g Intakeup ℃a
G～Exhaust＝Exhaust initial ℃a
g exhaustlow ℃a≤G～exhaust≤ge xhaustup ℃a
G～crankshaft＝0℃r
g crankshaftlow ℃r≤G～crankshaft≤g Crankshaftup ℃r
g Intakelow 、g Intakeup the upper limit and the lower limit of the tolerance of the geometric deviation angle G-intake reference value of the intake camshaft are adopted; g exhaustlow 、ge xhaustup The upper limit and the lower limit of the tolerance of the geometric deviation angle G-exhaust reference value of the row camshaft are adopted; g crankshaftlow 、g Crankshaftup Is the geometric deviation angle G of the crankshaft to the upper extent C An upper tolerance limit and a lower tolerance limit for the rankshaft criterion; DEG C r represents the angle by which the crankshaft rotates about the center of rotation; DEG C a represents the angle by which the camshaft rotates about the center of rotation;
if the geometric deviation angle G exceeds the range shown by the judgment standard, judging that the geometric deviation angle G is unqualified, indicating that the geometric deviation angle G is out of tolerance, requiring manual intervention for repairing, reassembling and adjusting the timing, and returning to the step 1 after repairing; if the geometric deviation angle G does not exceed the range shown by the judgment standard, judging that the geometric deviation angle G is qualified;
step 303, entering a judging flow of a Hall sensor system error C, wherein the Hall sensor system error C comprises three values of an effective deviation angle E-intake of an intake camshaft and an effective deviation angle E-exhaust of a row camshaft and an effective deviation angle E-crankshaft of a crankshaft, and the judging standard is as follows:
C＝＝E～intake
E～intake＝H-(G～intake)-(M～Intake)
d intakelow ≤E～intake≤d intakeup
wherein d intakelow And d intakeup Respectively representing the upper and lower limits of the allowable maximum relative deviation angle of the intake camshaft; M-Intake is the machining tolerance of the Intake camshaft;
C＝＝E～exhaust
E～exhaust＝H-(G～exhaust)-(M～Exhaust)
d exhaustlow ≤E～Exhaust≤d exhaustup
wherein d exhaustup And d exhaustlow Respectively representing the upper and lower limits of the allowable maximum relative deviation angle of the exhaust camshaft; M-Exhaust represent Exhaust camshaft machining tolerances;
C＝＝E～crankshaft
E～crankshaft＝H-(G～crankshaft)-(M～Crankshaft)
d crankshaftlow ≤E～Exhaust≤d crankshaftup
wherein d crankshaftup And d crankshaftlow Respectively representing the upper and lower limits of the maximum allowable relative deviation angle of the crankshaft; M-Crankshaft represents Crankshaft machining tolerance;
when the system error C of the Hall sensor exceeds the value range according to the judging standard, judging that the positive effective angle H is unqualified, indicating that the fault of the timing system needs to be manually intervened for repairing, and returning to the step 1 after repairing; and if the system error C of the Hall sensor does not exceed the value range, judging that the positive effective angle H is qualified.
5. The method for diagnosing engine faults based on a multi-level progressive inspection principle as claimed in claim 1, wherein in step 4, the crank angular domain relationship is a vibration acceleration-crank angular domain relationship; the acceleration time domain relationship is vibration acceleration-crankshaft rotational speed.
6. The method for diagnosing engine faults based on the multi-level progressive detection principle as claimed in claim 5, wherein the contribution of vibration of the reciprocating linear motion type parts of each cylinder to the vibration acceleration can be rapidly identified through analysis of the vibration acceleration-crank angle domain.
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