2012年下学期期末考试发动机电控技术复习题（In 2012, the final examination of the final test engine will be reworked）.doc

2012年下学期期末考试发动机电控技术复习题（In 2012, the final examination of the final test engine will be reworked） Principle: Carmen vortex caused by changes in air density, affected by the signal generator to send the ultrasonic arrival of the receiver or become early or late, measured the phase difference, the use of amplifiers to form a rectangular wave, rectangular pulse frequency The frequency of the swing for the card door. Detection: Turn the ignition switch to ON position, check the voltage between VC and E2 should be 5V, KS and E2 voltage should be 2 ~ 4V. 88. How does the hot air flowmeter work? How to complete self-cleaning effect? What about the maintenance process? What is the superiority of the hot film air flowmeter? Working principle: RA, RB, RH, RK composition Whiston bridge circuit. (Hot wire resistance RH, temperature compensation resistor RK) Air flow RH → RH temperature reduction → RH resistance decreases → bridge loss of balance → control circuit to increase the current flowing through RH to restore the RH resistance, the bridge rebalance → RA both ends of the voltage increase, this The voltage is the sensor signal of the hot air flow meter Self-cleaning effect After the engine is stopped, the microcomputer centralized control device automatically heats the hotline to about 1000 ° C and burns the dust attached to the hotline. Circuit detection Turn on the ignition switch, do not start the engine, measured E and D, E and C between the voltage for the battery voltage. B and C between the signal voltage engine work for 2 ~ 4V, the engine does not work for the 1.0 ~ 1.5V, F and D between the voltage, turn off the ignition switch, the voltage should be zero and after 5s jump on the students, after 1s In the back to zero, that self-cleaning signal is good.