SU1075113A1 - Method of diagnosis of internal combustion engine and device for effecting same - Google Patents

Abstract

1. A method for diagnosing an internal combustion engine, which consists in registering the vibroscale with a converter by parameters of the vibration pulses from the test interface, the vibration pulses in the ultrasonic frequency range, processing the signals, and determining the state of the interface, differing in that , in order to improve the accuracy of diagnostics and noise immunity, the allocation of vibration pulses is carried out in the resonance region of the vibration converter by differentiation and filtering, Otherwise, the order of differentiation is chosen equal to or greater than three. € /)

Description

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2. A device for diagnosing an internal combustion engine, comprising a measuring and computing unit, a phase selection device, a first and second conversion circuits, each of which contains a vibrator and connected in series, the first and second circuits being connected respectively to the measuring and computing unit and

1075

with a phase-selective device, which are interconnected, characterized in that, in order to increase the diagnostic accuracy and noise immunity, it additionally contains two differentiators, each of which is connected to a vibrating transducer with a filter, and the latter is tuned to the resonant region of the vibrator.

The invention relates to the field of diagnostics of mechanisms and machines, in particular, dg; gamers of internal assembly (two). There are known methods for diagnosing toSCl, which consist in registering the parameters of the vibratory pulses from the mating under study, and they select the pulses in a predetermined range of frequencies And, The disadvantages of this method are with low accuracy and reliability, since the allocation of the vibrational signal in the region natural vibrations of the vibroacoustic channel located in the audio frequency range are associated with the distortion of the vibro-impact response and the presence of interference from unchecked mates. The accuracy of the method is also associated with a large value of the vibration oscillation time in the vibration 5 channel at the sound frequency, which exceeds the duration of the impact-response in the engine with the quality factor U t0-200 and many times (up to one hundred or more) times. Methods of diagnosing the internal combustion engine j are known that the vibration pulses are recorded by the parameters of the vibration pulses from the NIN sample under study, and the vibration pulses are recorded in the ultrasonic frequency range, the signals are processed and the conditions are determined by comparing them with the standard e mate C2. The disadvantages of the known method and device are low accuracy and noise immunity, which are associated with instability of parameters and low attenuation of the signal of the vibrator at its difference frequency. The aim of the invention is to improve the accuracy of diagnosis and noise immunity. The goal is achieved by the choo in the method of diagnosing the internal combustion engine, which consists in recording the parameters of the vibration pulses from the tested coupling by the vibration transducer, and the vibration pulses are allocated in the ultrasonic frequency range, the signals are processed and the matching state is determined by comparison vibration pulses are carried out in the resonance region of the vibration transducer by differentiation and filtering, with the order of differentiation being chosen equal or greater have three. In the device for diagnosing the internal combustion engine, containing, measuring and computing unit, phase selection device, the first and. the second transformation chain, each of which contains vibropress; the former and the filter, connected in succession, the first and second circuits, respectively, connected to the measuring and computing unit and phase selection device, which are interconnected, additionally included two differential diameters, each of which is connected to the vibrator transducer with a filter, and the last on the resonance region of the vibration transducer. Fig, 1, and shows the spectrum of the shock pulse; in fig. 1.6 — the normiro3 bath is the amplitude-frequency characteristic of a piezoelectric vibrating plate; in fig. Г, в - differentiation operator; Fig. 1, the spectrum of the vibrosignal after diffraction; in fig. 2 is a block diagram of the device. The idealized frequency spectrum (see Fig. 1, a) of the impact in conjugation of the mechanism is represented by the formula: sindf n Jfc- I where tt is the acceleration amplitude; f is the frequency (selection) of the signal; t is the impact-impact duration; ,14. The hop frequency response of the vibroaxis converter is described by the relation (Fig. 16): 1I / LF / cW) where fj, Q is the resonance frequency and the q of the viral transform From expression (5), it can be inferred that the signal amplitude depends on the frequency most strongly areas of resonance inbreeding. It depends on the accuracy of the signal selection at the frequency and the Q value of the vibration transducer. Since the quality factor of C1 7 / -10, when c lectures a signal at a frequency, the expression (5) will look like: 145MJ Hct (j4) It is known that with an increase in the frequency of signal selection, a decrease in the attenuation and vibration absorption of the diagnosed object is observed. With this in mind, as well as expressions (4) and (56) in the resonant region of the vibrator, the amplitude of the selected vibro-impulse is maximum according to the law: (L “a / (s) 3L where n 7.3 is an exponent. Due to the fact that the value of the quality factor of the vibroacoustic channel and the absorption of the vibration signal is unknown, we assume that ...o6. Without taking into account the process of establishing and I decay of oscillations during the vibration pulse, the process of vibration at frequency f is described by sinusoidal A (t | jSir. (Zlfi-H j where (A | the amplitude of the component with the frequency f is found as a function of STK (6); i - current time; If - the initial phase of oscillation. Selection of high-frequency components from the entire spectrum of vibration pulses is difficult due to their small value. Reduction of amplitudes of frequency components of selectable vibration pulse with an increase in frequency can be compensated by law (6) by differentiation, the operator is shown in Fig. 1c. Then the transformed spectrum of the components of the vibrosignal is described by the formula: A (). (, C8) is the differential operator of the HZ-th order. Derivatives of sine and cosine cosine and sine, respectively, differ from each other only in the initial phase V, which does not matter when measuring the vibration parameters of the internal combustion engine; neither Then the envelope of the maximum amplitudes of the vibration spectrum takes the form: / MaKc El Kf, O) and the full spectrum of the differentiated vibration signal:) Kc ((sit) (jTf), (10) where K is the proportionality coefficient. If you take, then the spectrum of the differentiated signal of the vibrator, The former has a nearly even envelope of the maximum amplitudes of the frequency components of an impact (Fig. 1 g). From a signal with such a spectrum by filtering, high-frequency components of the resonator vibrator region are easily separable. It is taken sufficient to suppress low-frequency components, and the exact equality is not necessary; if the signal is sapiccin, the vibrating transducer diagnoses two in the resonance region, for example, f 300 kHz 7 to 32 kHz error components (1) (3) are absent, the error from the deviation of the frequency of the vibrator transducer : V., Oll, /. - .. +7 ° v II, where d1d is the deviation of the frequency of the vibration transducer in the conditions of diagnosis. At both kHz and about 32 kHz, the error is much less than the components of the error according to the prototype method. It is known that with an increase in the frequency of oscillations, the quality of the material of the propagation body oscillates and the absorption decreases, which means that the amplitude of the vibration in the ultrasonic region of the vibrator is less distorted by the internal resonances of the acoustic channel of the internal combustion engine, According to the data of the experiment at an I 300 kHz frequency in the vibrating signal of the injector, diesel engine of the SMD-62 type, the amplitude of the vibration pulses from unchecked The interference mapping (interference) is up to 10 times less than at the frequency f cj f, - 32 kHz. Improving the accuracy of the selection of vibro impulses and, thus, improving their compliance with the working processes of the internal combustion engine will provide an increase in the accuracy and reliability of diagnostic measurements. According to the phase and amplitude parameters of the vibration pulses selected by the described method, the technical condition of the diagnosed mechanism is determined according to the well-known dependences of parametric pulses on the technical condition two. Thus, the proposed conditions for implementing the method of vibration diagnostics provide an increase in the noise immunity and accuracy of determining the technical condition two. The device carrying out the proposed method contains vibration converters 1 and 2, differentiators 3 and 4, filters 5 and 6, measuring and calculating unit 7 and phase selection device 8, the selective vibration transducer 1 is attached to the control point of the diagnosed ICE interface, and the vibration converter 2 synchronization to the interface, the vibration pulse of which repeats at a certain moment during the full cycle of the internal combustion engine, As a source of the sync signal, serves, for example, a nozzle, the vibration pulse of which repeats for each two rotations of the crankshaft of the four-stroke internal combustion engine, vibration transducer signals 1 and 2 are fed to the inputs of differentiators 3 and 4, respectively; the biometric signals with the transformed spectrum from the outputs of differentiators 3 and 4 are fed to F1-shtry 5 and 6 to select a signal in the resonant region of the vibration transducer, using a signal the synchronization vibration transducer 2 by the phase-selection device 8 out of two signals of the reference point, for example, the top dead center (TDC) of the piston, in the work cycle, one is allocated, corresponding to the checked operation To which the ICE process, the Phase Selection Device 8, operating synchronously with the ICE, produces gating pulses applied to the computation unit 7 3 for the time interval of the workflow of the tested mate. The measuring and computing unit 7 measures the amplitude values or the phase of the vibration pulses received by the inverter 1 during the pulse, gating. As an example, we consider the diagnosis of a piston-piston group (CPG) of one of the cylinders two. For this, the measuring vibration transducer 1 is installed in the corresponding control point of the engine block. The synchronization vibration converter 2 is attached, for example, to the second injector of the internal combustion engine. The amplitude of the vibration pulses from the impact is put at the rear of the piston at TDC, at the beginning of the expansion stroke in the cylinder being checked. It is known that there is an almost linear relationship between the amplitude of the AV signal (5 pulses and the gap in the CNG. Then the error in determining the CNG gap (diagnostics) is equal to the error of selection and measuring the amplitude of the vibration pulses. Reducing the error in the vibration of the LAN signal ensures that the diagnostics accuracy of its technician will reduce its accuracy. Selection of the signal during the measurement of the phase of the working process, for example, the fuel advance angle by the fuel pump section, is carried out in the same way as described above. the distributor 2 is mounted on the checked section of the fuel pump. The measurement is performed on the front edge of the vibration pulse exceeding the actuation level.

Fig. 2 of the reference point in relation to which the fuel advance angle is determined is usually used TDC. For an accurate and reliable measurement, it is necessary to trigger the phase meter from the same part of the leading edge of the vibration pulse when the measurement is repeated on many internal combustion engines. This is ensured by the stability of the amplitude and the short duration of the fronts of the vibration pulses, selected in the resonant region of the vibrating transducer. The proposed method and device provide for increasing the accuracy and noise immunity of vibration diagnostics by using vibration pulses allocated in the rezino-nance region of the vibration transducer to judge the technical condition of the LAN mechanisms.

Claims (2)

1. A method for diagnosing an internal combustion engine, which consists in registering the parameters of vibration pulses from the interface being studied by the vibration transducer, the vibration pulses being injected in the ultrasonic frequency range, processing the signals, and comparing them with the standard, determine the state of coupling, which differs in the purpose of improving the accuracy of diagnosis and noise immunity, the selection of vibration pulses is carried out in the resonance region of the vibration transducer by differentiation and filtering, and oryadok differentiation is selected to be three or more. ho 10751 2. A device for diagnosing an internal combustion engine, comprising a measuring and computing unit, a phase-selective device, first and second conversion values, each of which contains a vibration transducer and a filter connected in series, the first and second circuits being connected to the measuring and computing unit and to the phase-selective device, respectively which are interconnected, characterized in that, in order to improve the accuracy of diagnosis and noise immunity, it additionally contains two differentiator, each of which is included in the connection of the vibration transducer with the filter, and the latter is configured for the resonance region of the vibration transducer.