Repair of scraper level sensor of the hottest pave

2022-07-23
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Repair of material level sensor of paver scraper

during the construction of a V gele-s1800 paver, the right scraper feeder suddenly failed to work normally. The machine adopts a proportional material conveying automatic control system, which is composed of a material level sensor and a proportional solenoid valve. The function of the material level sensor is to adjust the feeding speed in proportion to the change of the height of the material pile

McClelland pointed out: "the current and future vehicles will adopt various energy-saving materials as contact magnetoresistance angular displacement sensors, which are divided into two parts: sensor and controller, and are made into one. The main components of the sensor are magnetoresistance and permanent magnet. The magnetoresistance is made of semiconductor material. The characteristic of this material is that its resistance can change with the strength of the external magnetic field (magnetoresistance effect) ; The permanent magnet is fixed on the rotating shaft connected with the sensor rotating arm. When the height of the asphalt concrete pile changes and the sensor rotating arm rotates, the distance between the magnet and the magnetoresistance is changed, so that the magnetic flux passing through the magnetoresistance changes, and the output value of the magnetoresistance changes accordingly. The resistance value is input to the controller, Through its electronic circuit, its 58R terminal adjusts the voltage of the proportional solenoid valve coil of the variable feed pump, so that the feeding speed changes in proportion to the height of the pile, so as to keep the height of the pile basically constant

open the side cover of the sensor and rotate the rotating arm to make the permanent magnet and the magnetoresistance produce angular displacement. As a result, the reading of the ammeter has not changed. This phenomenon indicates that the controller has been unable to adjust the voltage of the proportional solenoid valve coil, so that the feeder can not automatically control the height of the pusher. The reason for this problem may be: the electronic circuit board of the controller fails; The magnetoresistance is damaged

unplug the four wires of the relevant connectors on the controller, measure the resistance value between the terminals with a resistance gear, and compare the measured value with the value measured during normal operation. The results are consistent, indicating that the electronic circuit board of the controller is normal, and the problem should be caused by the magnetoresistance

the resistance value of the magnetoresistance is measured, and the results are only a few ohms in both positive and negative phases. This situation indicates that the semiconductor material of the magnetoresistance has slipped and been broken down in the process of the experiment. As a result, the resistance value cannot change with the rotation of the rotating arm, so that the sensor cannot work normally

replace the magnetoresistance, plug in all wires (turn on the power supply, and manually move the rotating arm to realize stepless speed regulation). At this time, the voltage value between 54 and 58R of the controller is the voltage value acting on the coil of the proportional solenoid valve. When the voltage reaches 21.8v, "Kearney partner Li Jian said at the meeting that the scraper feeder will reach the maximum speed (the rotating arm will turn to the lower limit baffle position); When the voltage is lower than 15.8v, the scraper feeder adopts electro-hydraulic servo to stop (the rotating arm turns to the upper limit baffle). The repair work was less than 2h, which ensured the paving quality and project progress of the pavement. (end)

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