WORK MACHINE

• US 20180282969A1
• Filed: 11/24/2017
• Published: 10/04/2018
• Est. Priority Date: 03/31/2017
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: HITA, Masafumi, SHIBATA, Kouichi
• Granted Patent: US 10,619,326 B2
• Time in Patent Office: Days
• CPC Class Codes: E02F 3/32 working downwardly and towards the machine, e.g. with backhoes
• CPC Class Codes: E02F 3/425 Drive systems for dipper-arms, backhoes or the like
• CPC Class Codes: E02F 3/437 providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant
• CPC Class Codes: E02F 3/439 Automatic repositioning of the implement, e.g. automatic dumping, auto-return E02F3/438 takes precedence
• CPC Class Codes: E02F 9/2203 Arrangements for controlling the attitude of actuators, e.g. speed, floating function
• CPC Class Codes: E02F 9/2271 Actuators and supports therefor and protection therefor
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/262 with follow-up actions to control the work tool, e.g. controller
• CPC Class Codes: E02F 9/265 with follow-up actions (e.g. control signals sent to actuate the work tool)
• CPC Class Codes: F15B 19/002 Calibrating
• CPC Class Codes: G05B 19/416 characterised by control of velocity, acceleration or deceleration G05B19/19 takes precedence

Abstract

The invention provides a work machine that achieves high accuracy of forming a target construction surface and reduced fuel consumption. A trajectory corrective Pi pressure calculation section calculates a trajectory corrective pressure, which is a control signal for a boom cylinder, based on the distance from a front work device to a target construction surface such that the motion trajectory of the work device is maintained above the target construction surface. A power corrective Pi pressure calculation section calculates a power corrective pressure, which is a control signal for the boom cylinder, based on the bottom pressure of an arm cylinder when the difference between the target power and actual power of the arm cylinder is larger than a predetermined output power value. The boom cylinder is controlled based on the larger of the power corrective pressure and the trajectory corrective pressure while the arm cylinder is being operated.

Claims

1. A work machine comprising:

a multi-joint work device for forming a target construction surface;

a plurality of hydraulic actuators for driving the work device based on control signals; and

a controller including a trajectory corrective control signal calculation section for calculating based on a distance from the work device to the target construction surface a trajectory corrective control signal that is a control signal for at least one correction target hydraulic actuator among the plurality of hydraulic actuators such that a motion trajectory of the work device is maintained above the target construction surface, characterized in that

the controller further includes a power corrective control signal calculation section for calculating, when a difference between a target power and an actual power of at least one particular hydraulic actuator among the plurality of hydraulic actuators is larger than a predetermined output power value, a power corrective control signal that is a control signal for the correction target hydraulic actuator based on a drive pressure of the particular hydraulic actuator, and

the correction target hydraulic actuator is controlled based on a larger one of the power corrective control signal and the trajectory corrective control signal while the particular hydraulic actuator is being operated.

2. The work machine of claim 1, wherein, when the drive pressure of the particular hydraulic actuator is larger than a predetermined pressure, the power corrective control signal calculation section calculates the power corrective control signal such that the work device moves away from the target construction surface by an operation of the correction target hydraulic actuator.

3. The work machine of claim 1, wherein, when the drive pressure of the particular hydraulic actuator is smaller than a predetermined pressure, the power corrective control signal calculation section calculates the power corrective control signal such that the work device moves closer to the target construction surface by the operation of the correction target hydraulic actuator.

4. The work machine of claim 1, wherein

the work device is a front work device having a boom, an arm, and a bucket,

the particular hydraulic actuator includes an arm cylinder for driving the arm, and

the correction target hydraulic actuator is a boom cylinder for driving the boom.

5. The work machine of claim 1 further comprising:

a swing structure having the work device attached thereto; and

a hydraulic motor for rotating the swing structure based on a control signal,

wherein, when a control signal for the hydraulic motor is being output, the controller suspends the calculation of the trajectory corrective control signal by the trajectory corrective control signal calculation section and the calculation of the power corrective control signal by the power corrective control signal calculation section.