During the construction of the paver, the scraper feeder on the right side suddenly fails to work normally. The machine adopts proportional automatic feeding system, which is composed of material level sensor and proportional solenoid valve. The function of the level sensor is to adjust the feeding speed proportionally according to the change of the pile height.

 

 

 

The material level sensor is a contact type magnetoresistance type angular displacement sensor, which is divided into two parts: the sensor and the controller, and is made into a whole. The main components of the sensor are magnetoresistance and permanent magnet. Magnetoresistance is made of semiconductor material, which is characterized by that its resistance can change with the strength of the external magnetic field (magnetoresistance effect); The permanent magnet is fixed on the shaft connected with the sensor arm. When the height of the asphalt concrete pile changes and the sensor arm rotates, the distance between the magnet and the magnetoresistor is changed, so that the magnetic flux passing through the magnetoresistor changes. Then the output value of the magnetoresistor changes accordingly, and this resistance value is input to the controller, Through its electronic circuit, its 58R terminal regulates the voltage of the proportional solenoid valve coil of the feed variable pump, so that the feed speed changes proportionally to the height of the pile, so as to keep the pile height basically constant.

 

 

 

 

Open the side cover of the sensor, and rotate the rotary arm to make the permanent magnet and the magnetoresistor produce angular displacement. As a result, the reading of the ammeter does not change. This phenomenon indicates that the controller can no longer adjust the voltage of the proportional solenoid valve coil, resulting in the feeder can not automatically control the height of the feed. The cause of this problem may be: the electronic circuit board of the controller fails; The magnetoresistance is damaged.