# US 2019/0169818 A1 · Work machine

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- Number: US 2019/0169818 A1
- Document ID: US20190169818A1
- Status: Published application
- Kind: A1
- Application number: 16/302,109
- Filed: 2017-04-05
- Published: 2019-06-06
- Earliest claimed: 2016-05-26
- Assignees: Hitachi Construction Machinery Co., Ltd.
- Applicants: Hitachi Construction Machinery Co., Ltd.
- Inventors: Ryu NARIKAWA; Manabu EDAMURA; Kouji ISHIKAWA; Shiho IZUMI
- Web page: https://patentgrep.com/patent/US20190169818A1

## CPC

- E02F 3/435: {for dipper-arms, backhoes or the like}
- E02F 3/437: {providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant}
- E02F 3/43: Control of dipper or bucket position; Control of sequence of drive operations
- E02F 9/20: Drives; Control devices (gearings in general F16H; controlling in general G05; electric multi-motor drives H02K, H02P)
- E02F 9/2004: {Control mechanisms, e.g. control levers (control levers per se G05G)}
- E02F 9/26: Indicating devices {(E02F5/145 takes precedence)}
- E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00)

## Abstract

A hydraulic excavator includes a controller (40) that executes region limiting control to forcibly raise a boom (8) in such a manner that a position of a tip end of a bucket (10) is kept on a target excavation surface and within a region above the target excavation surface if an operation device (45b, 46a) issues an action direction to an arm (9) or the bucket. The controller determines which is selected as a control mode over a raising speed of the boom at a time of executing region limiting control, a first mode or a second mode specified by a raising speed lower than a raising speed of the first mode if the tip end of the bucket is located below the target excavation surface, and controls the raising speed of the boom based on a result of determination.

## Claims

### Claim 1

A work machine comprising:
a travel structure;
a swing structure swingably attached onto the travel structure;
a multijoint work implement that is attached to the swing structure and that includes a boom, an arm, and a bucket;
an operation device that outputs an action direction to each of the travel structure, the swing structure, the boom, the arm, and the bucket in response to an operator's operation; and
a controller configured to execute region limiting control to forcibly raise the boom in such a manner that a position of a tip end of the work implement is kept on a target excavation surface and within a region above the target excavation surface when the operation device issues the action direction to the arm or the bucket, wherein
the controller
includes a target action determination section that determines which is selected, as a control mode over a raising speed of the boom at a time of executing the region limiting control, a first mode or a second mode specified by a raising speed lower than a raising speed of the first mode when the tip end of the work implement is located below the target excavation surface, and
controls the raising speed of the boom during the region limiting control based on a result of determination by the target action determination section.

### Claim 2 (depends on 1)

The work machine according to claim 1, wherein
the target action determination section makes the determination based on a penetration amount of the tip end of the work implement into the target excavation surface, selects the second mode when the penetration amount is equal to or higher than a predetermined value, and selects the first mode when the penetration amount is lower than the predetermined value.

### Claim 3 (depends on 1)

The work machine according to claim 1, wherein
the target action determination section
makes the determination based on the action direction to the travel structure or the swing structure from the operation device and a position relationship between the target excavation surface and the tip end of the work implement, and
selects the second mode when the tip end of the work implement moves below the target excavation surface by the action direction to the travel structure or the swing structure from the operation device, and selects the first mode when the action direction to the travel structure or the swing structure from the operation device is not present.

### Claim 4 (depends on 2)

The work machine according to claim 2, wherein
the target action determination section makes the determination also based on a machine body tilt angle of the work machine, selects the second mode when the penetration amount is equal to or higher than the predetermined value, suspends the region limiting control when the penetration amount is lower than the predetermined value and the machine body tilt angle is equal to or greater than a predetermined angle, and selects the first mode when the penetration amount is lower than the predetermined value and the machine body tilt angle is less than the predetermined angle.

### Claim 5 (depends on 2)

The work machine according to claim 2, further comprising
an informing device that informs an operator of selection of the second mode when the second mode is selected.