SU932347A1 - Device for diesel internal combustion engine diagnostics - Google Patents

Description

(54) DEVICE FOR DIAGNOSTIC DIESEL ENGINE

INTERNAL COMBUSTION

The invention relates to mechanical engineering, and more specifically to the field of devices for vibro-acoustic diagnostics of diesel engines of internal combustion. A device for diagnosing a diesel internal combustion dricker is known, comprising an upper dead center sensor, a forcing stage, a trigger, a voltage driver, a vibration sensor, a selective amplifier, a threshold element and a pulse driver, the sensor of the dead center point being connected through the forming stage the trigger input and the control input of the voltage driver, the signal input of which is connected through the selective amplifier to the output of the vibration sensor and the signal input of the threshold element, the reference input of which is connected to the output of the voltage driver, and the output - with the input of the pulse driver I The disadvantage of the known device is that the accuracy of the diagnostic results is low. The purpose of the invention is to increase credibility. To achieve this goal, a switch, a comparison unit and a pulse selector are inserted into the device, and the output of the pulse shaper is connected via a switch to the first and second inputs of the comparison unit, the output of which is connected to the first control input of the pulse selector, the second control input of which is connected to the output the trigger and with the control input of the switch, and the signal input of the pulse driver is associated with the output of the shaping stage and with the clock input of the comparison unit. Comparison slot contains a memory element, two prohibition elements, a reversible counter, two decoders and a control trigger; moreover, the first and second inputs of the memory element serve as the first and second block inputs, the outputs of which through the corresponding prohibition elements are connected to the corresponding inputs of the reversible counter, The output of which is connected to the inputs of the defragragors, the output of each of which is connected to the control input of the corresponding prohibition element and the first and second inputs of the control trigger, the third input of which is It is connected to the third input of the memory element, and the output serves respectively to the synchronizing input and output of the block. The drawing shows a block diagram of a device for diagnosing a diesel internal combustion engine. The device contains an upper dead center sensor 1 (i.c.t.), connected via a second cascade 2 to triggers 3 and a control input of a reference voltage driver 4, the signal input of which is connected to the output of the vibration sensor 5 through a selective bis signal amplifier the input of the threshold element 7, the reference input of which is connected to the output of the imaging device 4, and the output - to the input of the imaging device 8 pulses, the output of which through the switch 9 is connected to the first and second inputs of the comparison unit 10, the output of which is connected to one of the control x inputs of the selector 11 pulses, another control input of which is connected to the output of the trigger 3 and to the control input of the switch 9, and the signal input to the output of the forming stage 2 and to the clock input of the unit 10. The block 10 contains the memory element 12, the outputs which, via elements 13 and 14, are connected to the summing and subtracting inputs of the reversible counter 15, the output of which is connected to the inputs of the digestors 16 and 17, trigger 18. The output of the decoder 16 is connected to the control input of the element 13 and to the single input of the trigger 18, output decipher torus 17 is connected to the control input of the element 14 and the zero input of the trigger 18, the first and second inputs of the element 12 by the first and second inputs of the block 10, and the third input of the trigger 18, combined with the third input of the element 12, and the output of the trigger 18 serve as the synchronizing the input and output of the block 10. The selector 11 is a logic circuit and can be performed, for example, in the form of two series-connected switches, the outputs of the first of which are connected to the inputs of the second. The device works as follows. Let the vibration sensor 5 be installed on the nozzle of the second four-cylinder engine with the series of cylinders I-III-IV-II, and the sensor 1 TDM. generates signals at the time of passage in the mt the first and fourth cylinders at compression cycles, i.e. for one 9 4 cycle of engine operation, sensor 1 generates two signals of an IDM. Accordingly, the signals from sensor 1 form a cascade of 2 for the engine cycle two narrow rectangular impulses, the leading fronts of which correspond to the moments of passage of rm. An impulse was chosen as a reference signal, the leading edge of which corresponds to the moment in mt the first cylinder on the compression stroke. The pulses from the output of the forming cascade 2 are fed to the input of the pulse selector 11 and simultaneously to the counting input of the trigger 3, to the control input of the reference voltage generator 4 and to the clock input of the comparison unit 10. Pulse selector 11 passes one of two pulses of forming cascade 2 at the output of the device during one cycle of the engine at a constant signal at the output of block 10 depending on the value of this signal and the phase of operation of the trigger 3 triggered by the falling edge of the pulse of the forming cascade 2. At that the pulse of the reference signal arrives at the output of the device with a single value of the signal at the output of block 10, if the pulse of the reference signal at the output of the trigger 3 sets a zero signal, and at a zero value of the output signal Lok 10 if the reference signal pulse at the output of flip-flop 3 is set to a single signal. The signal of the vibration sensor 5, installed on the nozzle of the second cylinder, through the selective amplifier 6, which performs amplification and frequency selection of the signal, is fed to the signal inputs of the threshold element 7 and the reference voltage driver 4. The last for each second pulse from the output of the forming cascade 2, i.e. after a time interval equal to the engine operating cycle, it forms a constant voltage at the reference input of the threshold element 7, which is proportional to, but lower in terms of the maximum value of the vibration signal, for an expiring time interval equal to the engine operating cycle. When the signal generated at the output of the amplifier 6 level at the reference input of the threshold element 7 is exceeded, the latter is triggered. At B1 of the driver 8, a pulse occurs at the input of the switch 9. The position of the switch 9 changes synchronously with the change in the value of the signal at the output of the trigger 3 so that in one of the half-function of the engine; (the output of the imaging unit 8 is connected to one, and in the other semi-loop to the other input of the block 10. At the same time, the first input of the unit 10 impulses from the imaging unit 8 when it is single, and - at zero signal at the output of the trigger 3. Block 10 changes its state by one counting unit at the end of each half cycle of engine operation by a signal from the forming stage 2, if during this half cycle, one or more pulses, t. E. It records the presence of at least one triggering of the threshold element 7 in the engine half-cycle. For simplicity, let us assume that the threshold element 7 during the engine half-cycle works no more than once and denotes. Nj and Nj are the number of pulses arriving at the first and second inputs of block 10, respectively. If after a certain number of engine cycles, the number of pulses at one of the inputs of block 10 exceeds the number of pulses at the other input by an amount equal to the hyster of M of block 10, the latter passes to one of its extreme states and changes the value of the signal at its output. Here, if NI-NJ M, then a 10 signal is set at the output of a single signal and, if NJ-NI M, then a zero signal is set at the output of a block 10. Let the phase of operation of trigger 3 be such that a zero signal is established from the pulse of the reference signal from the output of the shaping stage 2 at the output of trigger 3. Then the useful signal of the vibration sensor 5, which occurs when fuel is injected into the nozzle of the second cylinder, is formed in the interval of a single signal at the output of the trigger 3. Therefore, the pulse of the imaging unit 8, which occurs when the threshold element 7 in the half cycles of the useful signal of the vibration sensor 5 arrives only at the first input block 10. Accordingly, the second input of block 10 receives impulses arising in half-cycles adjacent to half-cycles of the useful signal, if the interference level triggers the threshold element 7. H Res certain number of cycles of engine operation due to the number NI of pulses bolschoy useful signal intensity exceeds the number of pulses N2 so that Nj-NI M and the output signal of the unit 10 is mounted unit. The latter translates the selector 11 into the selection mode of pulses of the forming cascade 2, which sets the zero signal at the output of trigger 3. As a result, the selector 11 permits only a pulse of the reference signal to be output to the engine cycle. Consequently, on the high side. The device generates a pulse sequence with a follow-up frequency equal to the frequency of engine operation cycles, and the leading edge of which corresponds to the moment of torque mt. the first cylinder on the compression stroke. Thus, at the output of the device, a sequence of pulses is formed, which is a reference for diagnostic devices that measure the phase characteristics of the engines, make a time selection per cycle of the operation of the engines, etc. The reference pulse sequence is also formed at the output of the device during another phase of operation of the trigger 3, since in this case the pulses formed when threshold element 7 is triggered in the half-cycle of the useful signal arrive at the second input of unit 10 and produce a zero signal at its output the selector 11 in accordance with another phase of operation of the trigger 3. The steady-state value of the signal at the output of the block 10, and hence the mode of operation of the selector 11, do not change until the corresponding and Changing the difference in the number of pulses at the inputs of block 10, which, with an appropriate choice of the hysteresis value of block 10, ensures stable operation of the device not only when pulses are lost in half cycles of the useful signal, but also when pulses appear in adjacent half cycles. Comparison unit 10 operates as follows. When a pulse arrives at the first input of unit 10, memory element 12 is activated and a single signal appears at the input of prohibition element 13. At the end of the half-cycle, the trailing edge of the pulse arriving at the synchronizing input of the block 10 produces a zero signal at the output of element 12. Thus, regardless of the number of pulses received in the current half-cycle to the first input of block 10, one pulse arrives at the input of element 13. Similarly, a pulse is formed at the input of element 14 when pulses arrive at the second input of block 10. The pulses through elements 13 and 14 arrive respectively at the summing and subtracting inputs of the reversing counter 15 with a capacity of N. The N value defines the hysteresis M of the block 10, and M (N- one). Decoders 16 and 17 are triggered when counter 15 is set to the (N-1) and 0, respectively. If at a certain time interval the number of pulses at the summing input of the counter 15 exceeds the number of pulses fed to its subtracting input by (N-1), then a number (N-1) will be fixed in the counter 15. The decoder 16 is triggered and a single signal is set at its output, a blocking element 13 and arriving at the single input of the trigger 18. As a result, the block 10 is set to the extreme state (N-1) k on the falling edge of the pulse entering the synchronizing input of the block 10 The trigger 18 is triggered at its output, and hence at the output of block 10, a single signal is established. ; The newly appearing pulses on the first input do not change the state of the counter 15, and, consequently, the value of the signal at the output of the block 10, since element 13 is blocked. The number in the counter 15 is changed and is equal to (N-2), if now the pulse arrives on. a subtracting input of counter 15. At the output of the decoder 16, a zero signal is again formed and element 13 is unblocked. The pulse arriving at the sync input of block 10 does not change the state of trigger 18, since at its single and zero inputs the signals have a zero value. If the counter 15 goes to the zero state, then the decoder 17, the blocking element 14, triggers. At the zero input of the trigger 18, a single signal is set and a pulse arriving at the synchronizing input of the block 10 at the output of the trigger 18, and consequently, at the output of the block 10, a zero signal is set. I Introduction of a switch, a comparison unit containing a memory element, barred elements, a reversible counter, decoders and a trigger, a pulse selector distinguishes the proposed device from the known one, since it allows to increase the reliability of diagnostics by means of noise immunity to synchronization time, which allows forming a reference impulse sequence with large values of dick instability of the vibrating signal and small values of the signal-to-noise ratio at the output of the vibration sensor.

Formula Invention

1. A device for diagnosing a diesel internal combustion engine, comprising

Sources of information taken into account in the examination 1. USSR author's certificate, in accordance with the certificate No. 2854781/25-06, cl. G 01 M 15/00, 1979. an upper dead center sensor, a cascade forming, a trigger, a reference voltage driver, a vibration sensor, a selective amplifier, a threshold element and a pulse driver, the upper dead center sensor being connected through the forming cascade to the trigger input and the control input of the reference voltage driver, the signal input of which is connected through a selective amplifier to the output of the vibration sensor and the signal input of the threshold element, the reference input of which is connected to the output of the reference voltage driver and output with a pulse driver input, characterized in that, in order to increase reliability, a switch, a comparison unit and a pulse selector are inserted into the device, and the output of the pulse shaper is connected to the first and second comparator inputs through the switch, the output which is connected to the first control input of the pulse selector, the second control input of which is connected to the trigger output and to the control input of the switch, and the signal input of the form; the pulse adjuster is connected to the output of the SCADA and sinhroniziruyupschm comparing input unit. 2. The device according to claim 1, wherein the comparison unit contains a memory element, two prohibition elements, a reversible counter, two decimal diggers and a control trigger, the first and second inputs of the memory element These serve as the first and second inputs of the block, the outputs of which through the corresponding prohibition elements are connected to the corresponding inputs of the retrospective counter, the output of which is connected to the inputs of the decoders, the output of each of which is connected to the control input of the corresponding prohibition element and the first and second inputs y ravl guide trigger, the third input of which is combined with a third input of the memory element, and the output timing are input, respectively. and block output.

Claims (1)

Claim 1. A device for diagnosing a diesel internal combustion engine, containing