SU1049772A1 - Method and apparatus for engine diagnostics - Google Patents

Abstract

1. A method for diagnosing an internal combustion engine according to the parameters of the piston rings sticking ability, consisting in registering gas pressure parameters in the engine crankcase, determining a generalized parameter and judging by its change, the sealing ability of rotary rings is different, that, in order to improve the accuracy, the recorded parameters of gas pressure are converted into a signal and measuring information, high-frequency components are extracted from the spectrum of a sensor for a given number of cycles frequencies exceeding the frequency of rotation of the engine shaft, and convert them into a generalized parameter as a product of the current value in the time signal. cl

Description

2. A method according to claim I, characterized in that the high-frequency components are selected during extension cycles.

3. A device for diagnosing the internal combustion engine, comprising a pressure parameter converter, an oscillation spectrum converter, a register counter, an upper dead center (TDC) marker, a selector, cycles and a control unit, the spectrum converter being designed as a frequency filter, a control pulse generator and matching circuits connected in series and connected between the parameter converter and the counter, the TDC marker is connected to the matching circuit via a selector, and through the block

control - with a counter, characterized in that in order to increase accuracy, the coincidence circuit is made in the form of an actuator circuit, the selector is made in the form of two drivers and a trigger, and the control unit contains a match circuit 2I, a cycle counter and a trigger, and the formers are connected between the input of the selector and in parallel with the inputs of its trigger, the output of which serves as the output of the Selector, circuit 2I is turned on at the input of the control unit and through the cycle counter is connected to one trigger input of the control unit, the output of which is the output of the trigger, with This other trigger input through the start button is connected to the 2I circuit, and the other output is in parallel with the 2I and ZI circuits.

, one

The invention relates to the technical diagnostics and testing of internal combustion engines.

A method for diagnosing an internal combustion engine is known by the parameters of the sealing ability of piston rings, which consist in registering the gas pressure parameters in the engine crankcase, determining a generalized parameter and judging by its change the sealing rings of the piston rings (I}).

Also known are devices that are applicable to such methods, including a parameter converter, for example, pressure, an oscillation spectrum converter, a recording counter, an upper dead center (TDC) marker, a clock selector and a control unit, the spectrum generator being made in the form of a filter, frequencies, controls pulse generator and a coincidence circuit, connected in series, are connected between the parameter converter and the counter, the TDC timer is connected through the selector to the coincidence circuit, and through the control unit events - with counter 11}.

The known methods require cylinder deactivation and do not provide reliable results in assessing the sealing ability of piston rings in a separate cylinder, since the static pressure of gases in the crankcase is determined by the sealing ability of the rings of all cylinders of a multi-cylinder engine.

These devices do not allow to increase the accuracy of diagnosis and diagnose the engine on separate cylinders during its operation.

The aim of the invention is to improve the accuracy.

This goal is achieved by converting the recorded gas pressure parameters into a measurement information signal, from the spectrum of which, for a given number of cycles, high-frequency components with frequencies exceeding

rotational speed of the motor shaft, and convert them to a generalized parameter in the form of the product of the current signal value by time.

The high frequency components are extracted at the expansion cycles.

In the device, this goal is achieved by the fact that the coincidence circuit is made in the form of an RFI circuit, the selector is designed as two drivers and a trigger, and the control unit contains a 2I matching circuit, a cycle counter and a trigger, and the drivers are connected between the input of the selector and parallel to its trigger inputs, the output of which serves as the output of the selector, the 2I circuit is turned on at the input of the control unit and, through a cycle counter, is connected to one trigger input of the control unit, the output of which is the trigger output, while the other trigger input is h Res start button associated with the circuit 2I, and the other output - with parallel circuits 2I and GI.

FIG. Figure 1 shows oscillograms of the pressure of gases in the crankcase under normal sealing ability of the rings, which fully comply with the technical conditions for the assembly of diesel engines; in fig. 2 - the same, with a deteriorated sealing ability (the thermal gap of the second compression ring is increased from 0.25 mm to 20 mm, the third compression ring is broken into two approximately equal parts); in fig. 3 is a device for carrying out the method. The oscillograms show curves 1 and II, which characterize the pressure of gases in the crankcase, recorded with a strain gauge and eddy-current pressure transducer, respectively; curve III of gas pressure in the combustion chamber; maximum PC pressure in the combustion chamber with the fuel supply turned off (the high-pressure pump plunger is raised); maximum pressure PI in the combustion chamber when fuel is fed into it. FIG. I and 2, each separately, indicate the presence of two characteristic processes of pressure oscillation of gases in the crankcase; a low frequency process with a frequency equal to the frequency of rotation of the motor shaft, and a high frequency process with frequencies much higher than the frequency of rotation of the shaft. At the same time, an increase in the maximum pressure in the combustion chamber from PC to Ft, which, as is well known, leads to an increase in the amount of gases erupting into the crankcase from the combustion chamber, leading to an increase in the intensity of high-frequency oscillations. Comparison between the curves of pressure fluctuations of gases in the crankcase shown in FIG. I and 2 show that the deterioration of the sealing ability of the piston rings leads to an increase in the intensity of high-frequency fluctuations in the pressure of gases in the crankcase. As a generalized parameter of these oscillations, their amplitude, frequency, etc. can be taken. However, the more complete characteristic of oscillations will be the area under the curve of the signal of oscillations over time, i.e. product of current value of oscillations by time. It is proposed to diagnose the engine using a generalized parameter. The pressure fluctuations of the gases in the crankcase in two ways. One of them consists in performing the following technological operations. Using a pressure transducer, they generate a signal reflecting the process of gas pressure fluctuations in the crankcase section of the diagnostic cylinder; The pressure oscillation signal is filtered, extracting components with frequencies above the shaft rotation frequency. For a certain number of engine cycles, a general parameter of the selection of high-frequency oscillations is determined, and by its change, the sealing ability of the portions of the rings in the cylinder being diagnosed is judged. The advantage of this method is the simplicity of its implementation. The second method has high accuracy and consists in performing the following sequence of technological operations for diagnosing ICE. Using a pressure transducer, a signal is generated representing the process of gas pressure fluctuations in the crankcase. In the intervals corresponding to the loosening steps in the cylinder being diagnosed, components with frequencies exceeding the frequency of rotation of the engine shaft are separated from the spectrum of the oscillation signal. For a certain number of engine cycles, a generalized parameter of the detected high-frequency oscillations is determined and, by its change, a change in the sealing ability of the piston rings in the cylinder being diagnosed is judged. The proposed method of diagnosing ICE can be implemented using the proposed device. Device for diagnosing internal combustion engines contains measuring transducer 1 for crankcase gases, phase TDC meter 2, spectrum converter 3 for fluctuations of pressure for crankcase gases, selector of 4 strokes, control unit 5 and recording counter 6. Generating, converting and transmitting the measuring information signal is provided by serial connection measuring converter 1, spectrum converter 3 and a recording counter 6. Forming, converting and transmitting control and formation provided posledovatelnoparallelnym compound TDC phase timer 2, a selector 4 cycles Rasschirennaya and the control unit 5. By controlling the inputs, the spectrum converter 3 is connected to the selector 4 and the control unit 5. The spectrum converter 3 is connected to the pressure transmitter I by the measurement information signal, and to the outputs of the selector 4 and the control block 5 by control signals .. To the selector inputs 4 and the control unit 5 are connected to the phase marker 2. The recording counter 6 is connected to the output of the spectrum converter 3.. The device works as follows. From the spectrum of oscillations of the pressure of the crankcase gases, the spectrum converter 3 separates the components in frequency exceeding the frequency of rotation of the crankshaft, and converts them into pulses whose frequency deviation is proportional to the amplitudes of the pulsations of these components. Spectrum converter pulses 3 enter the recording counter 6, where they are counted in accordance with the algorithm given by control unit 5 and selector 4, and name: control unit 5 sets the number of duty cycles during which the calculation is performed, and village 4 is the duration of the calculations d for one engine cycle. Since high-frequency pulsations of pressure fluctuations of crankcase gases are a consequence of gas breakthrough through the rings to the crankcase, and the impulses of converter 3 have a frequency proportional to their amplitudes, a number proportional to the sum of the areas of these high-frequency pulsations over a set number of cycles will appear on the display board of the recording counter 6. Thus, this number characterizes the generalized parameter of the relationship between the technical state of piston rings and the nature of the gas-gas process in the engine crankcase. It is a measure of the gas breakthrough into the crankcase and serves as a criterion used to diagnose two. The algorithm for calculating the generalized parameter is determined by a set of technical means, implementing a spectrum converter 3, an expansion clock selector 4, and a control unit 5. Spectrum converter 3 contains a detection filter. upper frequency 7, controlled pulse generator 18 (voltage-frequency converter) n logic coincidence circuit 9 of the ZI type; the expansion clock selector 4 contains pulse formers 10 "And with adjustable delays and trigger 12; control unit 5 contains a logic circuit of coincidences J3 type 2I, cycle counter J4 n trigger JS. In the initial state, the logic schemes of coincidences ZI and 2I are closed by the potential signal of trigger 15. After pressing the manual start button 16 with the very first pulse of TDC, trigger 15 is canceled, discarding the readings of registering counter b and opening the coincidence circuit of ZI and 2I. The latter begin to pass pulses, respectively, from a controlled generator of 8 pulses to registering counter 6 and from phase marker 2 to cycle counter 14. Pulse formers 10 and II delay TDC pulses for time intervals equal to ti and tj, respectively, set by the operator. These pulses transfer the trigger 12, from the output of which in the pre-electric circuit of each engine operating cycle to the control input of the coincidence circuit GI, the enabling signal of duration t 7 t | t .tj. When the loop counter reaches 14 of a predetermined number of cycles, trigger 15 is transferred, close the ZI and 2I matching schemes. In this case, the supply of pulses to the counters 6 and 14 is stopped. The display of the counting register CHAK9 6 shows a fixed number equal to the number of pulses transmitted from the controlled pulse generator 8, i.e. proportional to the sum of the areas bounded by the high frequency components of the pulsations present in the signal spectrum of the measuring transducer 1. The technical and economic advantages of the proposed invention are to improve the accuracy of determining the sealing ability of piston rings and to reduce the laboriousness of preparation and diagnostic operations.

FIG. 2

FIG.

Claims (3)

1. A method for diagnosing an internal combustion engine by the parameters of the sealing ability of the piston rings, which consists in registering the gas pressure parameters in the crankcase, determining a generalized parameter and judging by its change a change in the sealing ability of the piston rings, characterized in that, with In order to increase accuracy, the recorded gas pressure parameters are converted into a measurement information signal, from the spectrum of which for a given number of cycles high-frequency components are extracted per hour totals exceeding the engine shaft speed, and convert them into a generalized parameter in the form of the product of the current signal value by the time. Figure 1 ( 2, The method of π. 1, characterized in that the high-frequency. Components emit on the expansion cycles. 3. A device for diagnosing an internal combustion engine, comprising a pressure parameter converter, an oscillation spectrum converter, a recording counter, a top dead center marker (TDC), a selector, a clock and a control unit, the spectrum converter being made in the form of a frequency filter, a control pulse generator and a circuit matches connected in series and is connected between the parameter converter and the counter, the TDC marker is connected to the coincidence circuit through the selector, and through the control unit sensor, characterized in that in order to improve accuracy, the matching circuit is made in the form of a ZI circuit, the selector is made in the form of two shapers and a trigger, and the control unit contains a 2I matching circuit, a loop counter and a trigger, with the shapers connected between the input of the selector and parallel to the inputs its trigger, the output of which serves as the output of the Selector, circuit 2I is connected to the input of the control unit and connected through a cycle counter to one input of the trigger of the control unit, the output of which is the output of the trigger, while the other input is three ger through the start button is associated to a 2I, and the other way - in parallel with the schemes and 2I GI.