WHEEL LOADER AND BUCKET LOAD CALCULATION METHOD

• US 20200131739A1
• Filed: 09/19/2018
• Published: 04/30/2020
• Est. Priority Date: 09/29/2017
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: UEDA, Tomohiro, YOSHIKAWA, Masaki, ISHII, Takashi, MURAHASHI, Takayoshi, KAITOU, Masakazu, SHIMAZAKI, Koji, AOKI, Isamu
• Granted Patent: US 11,293,169 B2
• Time in Patent Office: Days
• CPC Class Codes: E02F 3/283 with a single arm pivoted directly on the chassis linkage mechanism for it E02F3/3405
• CPC Class Codes: E02F 9/26 Indicating devices E02F5/145 takes precedence
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G01G 19/10 having fluid weight-sensitive devices
• CPC Class Codes: G01G 19/16 having fluid weight-sensitive devices
• CPC Class Codes: G07C 5/02 Registering or indicating driving, working, idle, or waiting time only apparatus forming part of taximeters G07B13/00
• CPC Class Codes: G07C 5/08 Registering or indicating performance data other than driving, working, idle, or waiting time, with or without registering driving, working, idle or waiting time

Abstract

In an unloaded state of the bucket (3), a control device (30) calculates an unloaded moment (M₀) around a hinge pin G from the pressure of the lift arm cylinder that is detected by pressure sensors (15a, 15b), the angle of a lift arm that is detected by a lift arm angle sensor 14, and dimension data extracted from a vehicle body information database (35). In a loaded state of the bucket, the control device calculates a loaded moment (M₁) around the hinge pin G from the pressure of the lift arm cylinder, the angle of the lift arm, and the dimension data extracted from the vehicle body information database. The control device calculates the load (W) on the bucket by dividing the difference between the unloaded moment and the loaded moment by the horizontal distance (L_w) between the hinge pin and the gravity center position of the bucket.

Claims

1. A wheel loader comprising:

a vehicle body;

a working device that includes 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;

a lift arm angle sensor that detects the angle of the lift arm;

a pressure sensor that detects the pressure of the lift arm cylinder;

a control device that calculates a load on the bucket; and

a vehicle body information database that stores vehicle body information including dimension data on the working device,

wherein, in an unloaded state of the bucket, the control device calculates 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,

in a loaded state of the bucket, the control device calculates 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, and

the control device calculates 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.

2. The wheel loader according to claim 1,

wherein, at the time of initial operation of the wheel loader, the control device calculates the unloaded moment and stores the calculated unloaded moment in the vehicle body information database, and

when calculating the load on the bucket at the time of normal operation of the wheel loader, the control device calculates the load on the bucket from the unloaded moment and the loaded moment, the unloaded moment being stored in the vehicle body information database, the loaded moment being calculated based on measured data from the pressure sensor and the lift arm angle sensor.

3. The wheel loader according to claim 1, further comprising:

a bucket proximity switch that turns on when a rod of the bucket cylinder is in the most contracted state,

wherein the control device calculates the unloaded moment and the loaded moment in response to an ON signal from the bucket proximity switch.

4. The wheel loader according to claim 2, further comprising:

an engine that drives the vehicle body to travel; and

an engine rotational speed sensor that detects the rotational speed of the engine,

wherein, at the time of initial operation of the wheel loader, the control device calculates a plurality of values of the unloaded moment corresponding to a plurality of values of the engine rotational speed and stores the calculated values in the vehicle body information database in association with the values of the engine rotational speed, and

when calculating the load on the bucket at the time of normal operation of the wheel loader, the control device calculates the load on the bucket from the unloaded moment and the loaded moment, the unloaded moment being corresponding to the engine rotational speed detected by the engine rotational speed sensor, the loaded moment being calculated based on a measured value.

5. The wheel loader according to claim 2, further comprising:

a bucket proximity switch that turns on when a rod of the bucket cylinder is in the most contracted state,

wherein the control device calculates the unloaded moment and the loaded moment in response to an ON signal from the bucket proximity switch.

6. 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, and a vehicle body information database, 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; and

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.