Wheel loader and bucket load calculation method

A bucket load calculation method that is applied to a wheel loader and used to calculate a load on a bucket, the wheel loader including a vehicle body, a working device, a lift arm angle sensor, a pressure sensor, a vehicle body information database, and a display device that presents information to an operator, the working device including a lift arm, a lift arm cylinder, a bucket, and a bucket cylinder, the lift arm being disposed at the front of the vehicle body and coupled to the vehicle body via a hinge pin, the lift arm cylinder rotating the lift arm in a vertical direction, the bucket being coupled to a tip of the lift arm, the bucket cylinder rotating the bucket in the vertical direction, the lift arm angle sensor detecting the angle of the lift arm, the pressure sensor detecting the pressure of the lift arm cylinder, the vehicle body information database storing various vehicle body information including dimension data on the working device, the bucket load calculation method comprising:

• a first step of calculating, in an unloaded state of the bucket, an unloaded moment, namely, the moment around the hinge pin, from the pressure of the lift arm cylinder that is detected by the pressure sensor, the angle of the lift arm that is detected by the lift arm angle sensor, and the dimension data extracted from the vehicle body information database, and storing the calculated unloaded moment in the vehicle body information database as an initial learned value;
• a second step of calculating, in a loaded state of the bucket, a loaded moment, namely, the moment around the hinge pin, from the pressure of the lift arm cylinder that is detected by the pressure sensor, the angle of the lift arm that is detected by the lift arm angle sensor, and the dimension data extracted from the vehicle body information database;
• a third step of calculating the load on the bucket by dividing the difference between the unloaded moment and the loaded moment by the horizontal distance between the hinge pin and the gravity center position of the bucket, the unloaded moment being stored in the vehicle body information database in the first step, the loaded moment being calculated in the second step;
• and
• a fourth step of displaying the load on the bucket calculated in the third step on the display device.