Work vehicle

Patent metadata

Field	Value
Publication number	US-11035099-B2
Application number	US-201716085402-A
Country	US
Kind code	B2
Filing date	Sep 8, 2017
Priority date	Sep 30, 2016
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

A wheel loader includes a working device, a lift cylinder 152 which is a hydraulic actuator that drives the working device, a hydraulic pump 220 that supplies hydraulic oil to the lift cylinder 152 , a lift cylinder bottom pressure detector 252 that detects a pressure of the lift cylinder 152 , a control valve 221 that controls the amount of hydraulic oil to be supplied from the hydraulic pump 220 to the lift cylinder 152 , a vehicle acceleration detector 254 that detects a vehicle acceleration in a longitudinal direction, and a control device 240 . The control device 240 determines whether the working device has started excavation, or not, based on the lift cylinder bottom pressure detected by the lift cylinder bottom pressure detector 252 and the vehicle acceleration detected by the vehicle acceleration detector 254.

First claim

The invention claimed is:

1. A wheel loader comprising:
a frame;
a lift arm attached to a front of the frame;
a bucket attached to a distal end of the lift arm;
a hydraulic actuator that rotates the lift arm in a vertical direction;
a hydraulic pump that supplies hydraulic oil to the hydraulic actuator;
a hydraulic actuator pressure detector that detects a pressure of the hydraulic actuator;
a control valve that controls the amount of hydraulic oil to be supplied from the hydraulic pump to the hydraulic actuator;
a vehicle acceleration detector that detects a vehicle acceleration of the wheel loader; and
a control device that determines whether excavation by the bucket has been started, or not, based on an increasing speed of the pressure of the hydraulic actuator detected by the hydraulic actuator pressure detector and the vehicle acceleration detected by the vehicle acceleration detector, wherein
the control device includes an excavation start determination section that calculates an increment of the pressure of the hydraulic actuator per unit time, as the increasing speed of the pressure of the hydraulic actuator, according to the pressure of the hydraulic actuator detected by and input from the hydraulic actuator pressure detector and determines that excavation by the bucket has been started in a case where the increment is equal to or more than a predetermined first threshold value and the vehicle acceleration is equal to or less than a predetermined second threshold value.

2. The wheel loader according to claim 1 , further comprising:
a bucket cylinder stroke detector that detects a stroke of the bucket cylinder,
a lift arm angle detector that detects an angle of the lift arm, and
a vehicle traveling direction detector that detects whether a vehicle traveling direction is forward or backward, wherein
the control device includes a working device to ground angle acquisition section that acquires an angle of the bucket to the ground based on the stroke of the bucket cylinder detected by the bucket cylinder stroke detector and the angle of the lift arm detected by the lift arm angle detector and an excavation work prediction section that predicts that excavation by the bucket is performed in a case where the vehicle traveling direction detected by the vehicle traveling direction detector is forward and the angle of the bucket to the ground acquired by the working device to ground angle acquisition section falls within a predetermined range, and
the excavation start determination section determines whether excavation by the bucket has been started, or not, based on the increasing speed of the pressure of the hydraulic actuator and the vehicle acceleration in a case where the excavation work prediction section predicts that excavation by the bucket is performed.

3. The wheel loader according to claim 1 , wherein
the control device further includes an excavation determination notification section that gives notification to the effect that an operator is urged to lift the bucket in a case where it is determined that excavation by the bucket has been started.

4. The wheel loader according to claim 1 , wherein
the control device further includes a control valve control section that controls the control valve to start supply of hydraulic oil from the hydraulic pump to the hydraulic actuator in a case where it is determined that excavation by the bucket has been started.

Assignees

• Hitachi Construction Mach Co

Inventors

• Kimura Shota
• Osaka Tadashi
• Moriki Hidekazu
• Ishida Kazuo
• Itou Noritaka

Classifications

• E02F9/264 Primary

  Sensors and their calibration for indicating the position of the work tool · CPC title

• E02F9/2253

  Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission · CPC title

• E02F9/2228

  including an electronic controller · CPC title

• E02F9/2079

  Control of mechanical transmission (for hydrostatic transmission or hydraulic torque converter E02F9/2253) · CPC title

• E02F3/431

  for bucket-arms, front-end loaders, dumpers or the like · CPC title