JPH0324617B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an automobile diagnostic device, and more particularly to an automobile diagnostic device suitable for diagnosing a plurality of automobiles. Generally, an automobile diagnostic device has a configuration as shown in FIG. In other words, from Batsuteri 2,
When the starter 4 is driven by the circuit of the starter cable 46, starter 4, and ground cable 48 (usually the circuit is opened by a switch, etc.), the voltage and current measured by the battery voltage sensor 68 and battery voltage sensor 70 are detected. cable 82,
At 84, the signal is sent to the waveform shaping circuit 96. The output of the alternator appears on the ACG wiring 50, which is the output obtained by full-wave rectification of the alternating current generated in the generator coil 6 using the diode 8, and is measured by the ACG voltage sensor 72 and sent to the waveform shaping circuit 96 via the cord 86. The field of the alternator is provided by a field coil 12,
It is controlled by a voltage regulator 10. The voltage is measured by a field voltage sensor 74 and sent by a cord 88. When power is supplied from the battery 2 to the primary coil 18 of the ignition coil 14 via the wiring 52 and the current is interrupted by the interrupter 24 wired in the primary wiring 54, the two 2 are magnetically coupled by the iron core 16. A transient voltage is induced in the next coil 20. Capacitor 26 eliminates the spark arc that occurs when continuator 24 opens. Since the voltage of the primary coil appears in the form of repeated pulses in the primary wiring 54, this is measured by a primary voltage sensor 76 and sent by a cord 90. This is used as an engine rotation signal, etc. Secondary coil 20
The high voltage generated is led to the high voltage distributor 22 via high voltage cords 56 and 58. Therefore, when the rotor electrode 28 is rotated in the direction of the arrow, it faces the stator electrodes 30, 32, 34, and 36 one after another, and in synchronization with this, the ignition coil 14 generates high voltage.
The high voltage is plug cord 60, 62, 64, 66
through the spark plugs 38, 40, 42, respectively.
The high voltage applied to and sparking 44 is detected by a secondary voltage sensor 78 and sent via cord 92. Further, the reference cylinder sensor 80 detects the magnetic field caused by the current flowing through the plug cord 60, and the code 94 is detected.
Send by. This is to obtain a reference cylinder signal for determining the engine cylinder. The signals from each of the above sensors are appropriately shaped by the waveform shaping circuit 96 and then read into the microcomputer 100 via the interface 98, where the signals are analyzed to determine the presence or absence of a failure.
The results are displayed on the display 102 via 06. Note that reference numeral 104 is an operating device for inputting the number of cylinders and number of cycles of the vehicle to be diagnosed, and performing startup operations. FIG. 2 shows a waveform shaping circuit. The reference cylinder sensor 80 has a coil provided in a part of a closed magnetic circuit iron core, and a voltage is induced in the coil by the magnetic field caused by the current in the plug cord 60. This voltage is shaped by a capacitor 440 and input to a comparator 460 via a resistor 420. When this voltage is compared with the voltage of reference voltage source 450, its output is
It becomes a rectangular wave pulse as shown in Figure B. A in the same figure shows the output voltage waveform of the sensor 80. The signal from the primary voltage sensor 76 is formed by a reactor 484 and a capacitor 442, is input to a comparator 462 via a resistor 422, and is input to a reference voltage source 4.
52, resulting in the waveform shown in FIG. 3D.
C is the waveform before molding. The secondary voltage sensor 78 obtains a signal attenuated by resistance division, and has a voltage peak value Vp based on capacitive discharge and a discharge duration Td component based on inductive discharge, as shown in the waveform of FIG. 3E. Vp and Td
The product of is correlated with ignition energy. Vp is resistors 424, 426, analog switch 472 controlled by primary forming signal D, and capacitor 44.
4. It is held by a peak hold circuit consisting of FET 474 and resistor 428, and its output becomes G. On the other hand, the signal passed through a low-frequency three-wave filter composed of a reactor 486 and a capacitor 446 is inverted by an inverter 470, and is inverted by a resistor 430.
When the voltage is inputted to the comparator 464 via the voltage source 464 and compared with the voltage of the reference voltage source 454, the output becomes F. The detection signal of the ACG voltage sensor 72 is a DC voltage including ripples as shown in FIG. 3H. The ripple is a rectification ripple caused by the diode 8, and when one of the diodes 8 is disconnected, a part of the waveform of the ripple changes as shown by the broken line. This voltage signal is transferred by a capacitor 448 to a resistor 43.
The signal is inputted to an amplifier 480 via a voltage source 2 and amplified, and compared with the voltage of a reference voltage source 456 by a comparator 466, resulting in a rectangular wave as shown in FIG. 3K. Note that K is for the broken line of H. The battery current sensor 70 has a Hall element inserted in a closed magnetic circuit, and a voltage is generated by a magnetic field generated by a current flowing through the cable 48, and this is amplified by an amplifier 482 to obtain a signal voltage I proportional to the current. However, although the conventional diagnostic device described above can perform detailed diagnosis, it has problems such as being difficult to handle and expensive due to the large number of wiring connections between the sensor and the main body. Also,
When used in a repair shop or the like, there is a demand for diagnosing multiple vehicles almost simultaneously using one diagnostic device. SUMMARY OF THE INVENTION In view of the problems in the prior art described above, it is an object of the present invention to provide an automobile diagnostic device that is capable of diagnosing a plurality of automobiles at once. The above object, according to the present invention, is an automobile that uses a microcomputer to attach a plurality of sensors to the running parts of the automobile to be diagnosed, and diagnoses abnormalities in the automobile based on changes in the detected voltage from these sensors. In the diagnostic method, a plurality of subprograms are prepared in the memory of the microcomputer to be executed for each examination table, and the plurality of subprograms are sequentially executed, and detection voltages and battery voltages whose cycles change like an ignition signal are detected. An automobile diagnostic device characterized by measuring an analog detection voltage that does not change much with time like a voltage in a time-division manner, diagnosing inspection points of the automobile based on the measurement results, and displaying the results. It is achieved by doing so. FIG. 4 shows an embodiment of the invention. In the figure, a control unit 200 includes a microcomputer, which controls data transmission and reception, and analyzes and judges data. 30
0 is the main cable, clock line 302, address line 304, transmission line 306, reception line 3
It consists of 08. 310 is an individual cable, which is branched and connected from each line of the main cable. 400 and 410 are terminal transmitting and receiving units;
Each signal group is connected to this. 500,
Reference numeral 510 denotes an operating device, which will be described in detail later in FIG. 6, but includes a diagnosis start switch, a response switch, a switch for inputting the number of cylinders of the car, a number of engine cycles, an operating condition indicator, a display for judgment results, etc. There is. FIG. 5 shows the configuration of the control section 200, and the microcomputer 21 operates according to a program stored in the memory 220. The program contents will be described later. interface 23
Data is input and output via 0. 240 is a printer, which prints out the determination results for each vehicle to be diagnosed. A clock line 302 transmits clock pulses to the terminal transmitting/receiving sections 400 and 410.
This clock pulse is transmitted by the microcomputer 21.
This is designed to derive what 0 has.
The shift register 250 converts address data from a parallel signal to a serial signal and sends it to the address line 304. Shift register 260 similarly sends transmit data to transmit line 306. Shift register 270 is on receive line 3
It converts the serial signal coming in from 08 into a parallel signal and inputs it to the interface 230. FIG. 6 shows a concrete circuit of the operating devices 500 and 510, and a shift register 524 converts serial data of an address signal sent through the address line 304 into parallel data. Address data 5
The first bit among the bits is logic "1" and the four bits represent the address. In this example, up to eight vehicles can be addressed. When the first bit "1" is shifted to a predetermined position, it is input to the NOR gate via the inverter 532. The other 4 bits are each input to one input terminal of the EX-OR gate, and the other input terminal is each input to the memory 5.
36 signals are input. The memory 536 stores the address of its own channel, and is indicated by a fuse symbol.The bit that is connected to the power supply 538 and is energized is "1", and the bit that is disconnected from the memory 536 is "0". becomes. When all bits match, that is, when address data and address memory completely match, a decode signal pulse is output from the NOR gate. This decode signal pulse is passed through flip-flop 534.
given to one input terminal of AND gate 526,
And the latch circuit 540 and the shift register 522
given to. Transmission data sent via transmission line 306 is converted into a parallel signal by shift register 520, each bit of the parallel data is latched by latch circuit 540, and power amplified by drive circuit 542 consisting of an array of amplifiers 544. A light emitting diode 54 corresponding to each bit
Drive 6. The contents of the display by the light emitting diode 546 include informing the operator of the operating conditions of the vehicle, such as cranking, idling,
There are some that instruct the engine to run at 2000 rpm, turn on the headlight, and others that display the code number of the diagnostic result message. On the other hand, the shift register 52
2 converts each data from the engine cycle number setter 548, cylinder number setter 550 (4 bits corresponds to 2, 4, 6, and 8 cylinders), start switch 552, and response switch 554 into serial signals. Receive line 308 via AND gate 526
Send to. After this data has been sent, the control unit sends an address signal and the light emitting diode 54 again.
When the No. 6 lighting signal is sent, the decode signal sets the flip-flop 534 to "0", so there is no data to be sent from the shift register 522, and the receive line 308 is provided for another channel. FIG. 7 shows a specific circuit example of the terminal transmitting/receiving sections 400, 410, . The address signal from line 304 is converted to a parallel signal by shift register 724. The first bit of the address signal is "1" and the other four bits represent the address.
Each of these bits is connected to an inverter 732 and four
Enter EX-OR gate 730. The gate 730 has an address memory 766 consisting of four storage elements.
is connected to the input terminal. The memory 766 can be configured, for example, by connecting a voltage source 738 to one end of a fuse and connecting the gate 730 to the other end. In this case, the bit with the fuse blown provides a "0" signal. Address signal and address memory 76
When each bit of 6 matches, the NOR gate 728
A decode signal is output to the output terminal. This decode signal is transmitted to the latch circuit 740 and the flip-flop 7.
Given to 34. Serial data from line 306 is converted to a parallel signal by shift register 720, and the parallel signal is transferred to latch circuit 7.
40 and output to each output terminal of d ₁ , d ₂ , . . . d ₆ . The signals d ₁ , d ₂ , and d ₃ are used as chip selection inputs of the AD converter 742 . Select one of the battery voltage signal V _B on line 82, the alternator field voltage signal V _F on line 88, the battery current signal I, and the secondary voltage peak value signal V _P for each of d ₁ to _{d 6} outputs to 001000, 010000, 011000, 100000. _d4 ,
The signals d ₅ and d ₆ are used to select signals F, K, and D in FIG. 3. _d1 ~ _d6 output is 000100, 000010,
F, K, and D are selected for 000001, respectively.
When all three bits _d1 to _d3 are "0", the AD converter 742 does not operate, but when any one bit is "1", it operates. Its operation is triggered by applying a pulse to the reset terminal R, converts one of the analog signals selected by the output signals of _d1 to _d3 into a digital signal, and the conversion is completed. Then it issues a signal EOC. signal EOC
is provided by line 768 to the reset terminal R of shift register 722, where AD
The parallel signal of the digital output signal from the converter 742 is converted into a serial signal and the OR gate 750
and a signal on line 308 via AND gate 726. The AD converter 742 is reset when d ₁ , d ₄ , d ₅ , and d ₆ are all “0” and the output of the flip-flop 734 becomes “1”.
Or, d ₁ is “1”, flip-flop 734,7
36 are both "1" and the signal D becomes "1". In the former case, NOR gate 756
and via OR gate 752, and in the latter case
A reset signal is provided through AND gate 758 and OR gate 752. The former is an analog signal
V _B , V _F , and I are the targets, and the latter is the target G. Signals F and KD are output to AND gates 760 and 76, respectively, when the outputs of d ₄ , d ₅ and d ₆ are respectively "1" and the output of flip-flop 736 is "1".
2,764 and is sent to line 308 via OR gate 750 and AND gate 726. The input to flip-flop 736 is provided by the output signal of AND gate 735 which passes reference cylinder signal B when the output of flip-flop 734 is "1". Therefore, signals G, F, K, and D are sent on line 308 during one cycle of all cylinders of the engine. 8, 9, and 10 are part of a control flowchart by the microcomputer 210 of the control section 200. FIG. In Figure 8, “beginning” 60
0 indicates that the control program starts when the power of the device (not shown) is turned on. When the number of vehicles that can be diagnosed simultaneously is N, 602, 604, 606
Variable X(J) (J=1, 2,...
N) to 1. Symbol J is an auxiliary variable that repeatedly controls the plurality of terminal units 400, 410, . . . in order. Next, 608,
Through loops 609, 610, 611, and 612, subprograms with the same name as the value of A given in 609 are called repeatedly in order from 1 to N, and the value of variable It is updated and stored as the diagnosis progresses. An example of the memory configuration is shown in the table below.

【table】

Claims (1)

[Claims] 1. In a method of diagnosing a vehicle, a microcomputer is used to attach a plurality of sensors to the traveling location of the vehicle to be diagnosed, and to diagnose abnormalities in the vehicle based on changes in the detected voltage from these sensors,
A plurality of subprograms to be executed for each examination table are prepared in the memory of the microcomputer, and the plurality of subprograms are executed sequentially,
Detection voltages that change in period, such as ignition signals, and analog detection voltages that do not change over time, such as battery voltage, are measured in a time-division manner, and based on the above measurement results, the inspection points of the automobile are diagnosed, and the results are A method for diagnosing an automobile, characterized by displaying the following.