Slewing hydraulic work machine

Patent metadata

Field	Value
Publication number	US-11060261-B2
Application number	US-201816960388-A
Country	US
Kind code	B2
Filing date	Nov 16, 2018
Priority date	Jan 22, 2018
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

A slewing hydraulic work machine includes a slewing control device performing a slewing control in accordance with an applied slewing command operation, a boom control device performing a boom-raising control in accordance with an applied boom-raising command operation, a boom angle detector, and a capacity control section. The capacity control section calculates a command motor capacity based on a boom angle, generates a capacity command signal corresponding to the command motor capacity and inputs the signal to a slewing motor. During the performance of slewing and boom-raising operation, the capacity control section sets the command motor capacity to a value equal to or less than a base capacity when the boom angle is equal to or less than a slewing priority angle and sets the command motor capacity to a value greater than the base capacity when the boom angle is greater than the slewing priority angle.

First claim

The invention claimed is:

1. A slewing hydraulic work machine, comprising:
a lower travelling body;
an upper slewing body slewably mounted on the lower travelling body;
a working device mounted on the upper slewing body and including a boom connected to the upper slewing body so as to be raisable and lowerable;
a hydraulic pump that discharges hydraulic fluid;
a slewing motor formed of a variable displacement hydraulic motor that is driven by hydraulic fluid supplied from the hydraulic pump, the slewing motor configured to slew the upper slewing body in response to the supply of hydraulic fluid;
a slewing control device that controls a direction and a flow rate of hydraulic fluid supplied from the hydraulic pump to the slewing motor in accordance with a slewing command operation applied to the slewing control device for slewing the upper slewing body;
a boom cylinder that is operated, by hydraulic fluid supplied from the hydraulic pump, to raise and lower the boom;
a boom control device that controls a flow rate of the hydraulic fluid supplied from the hydraulic pump to the boom cylinder in accordance with a boom-raising command operation applied to the boom control device for actuating the boom in a rising direction;
a boom angle detector that detects a boom angle that is a rising angle of the boom; and
a capacity control section that controls a slewing motor capacity, which is a capacity of the slewing motor, wherein:
the capacity control section includes a command motor capacity calculation section that calculates a command motor capacity, which is a command value on the slewing motor capacity, based on the boom angle detected by the boom angle detector, and a command signal input section that generates a capacity command signal corresponding to the command motor capacity and inputs the capacity command signal to the slewing motor to thereby make the slewing motor capacity be a capacity corresponding to the command motor capacity; and
the command motor capacity calculation section is configured to set the command motor capacity to a predetermined base capacity or a capacity less than the base capacity when the boom angle is equal to or less than a predetermined slewing priority angle during a performance of a slewing and boom-raising operation in which the slewing command operation is applied to the slewing control device and the boom-raising command operation is applied to the boom control device simultaneously, and configured to set the command motor capacity to a capacity greater than the base capacity when the boom angle is greater than the slewing priority angle during the performance of the slewing and boom-raising operation.

2. The slewing hydraulic work machine according to claim 1 , wherein the command motor capacity calculation section is configured to set the command motor capacity to the base capacity during a performance of a single slewing operation in which the slewing command operation is applied to the slewing control device so as to cause hydraulic fluid discharged from the hydraulic pump to be supplied only to the slewing motor.

3. The slewing hydraulic work machine according to claim 1 , wherein the command motor capacity calculation section is configured to set the command motor capacity to the capacity greater than the base capacity, the capacity greater than the base capacity increasing with increase in the boom angle, when the boom angle is greater than the slewing priority angle during the performance of the slewing and boom-raising operation.

4. The slewing hydraulic work machine according to claim 1 , wherein the command motor capacity calculation section is configured to set the command motor capacity to the capacity less than the base capacity when the boom angle is less than a boom priority angle that is set at a value equal to or less than the slewing priority angle during the performance of the slewing and boom-raising operation.

5. The slewing hydraulic work machine according to claim 4 , wherein the command motor capacity calculation section is configured to set the command motor capacity to the capacity less than the base capacity, the the capacity less than the base capacity decreasing with decrease in the boom angle, when the boom angle is less than the boom priority angle during the performance of the slewing and boom-raising operation.

6. The slewing hydraulic work machine according to claim 4 , wherein the boom priority angle is less than the slewing priority angle, and wherein the command motor capacity calculation section is configured to keep the command motor capacity at the base capacity when the boom angle is within a middle angle range from the boom priority angle to the slewing priority angle during the performance of the slewing and boom-raising.

7. The slewing hydraulic work machine according to claim 1 , the slewing hydraulic work machine further comprises a boom-raising driving pressure detector that detects a boom-raising driving pressure, which is a pressure of the hydraulic fluid supplied to the boom cylinder during the performance of the slewing and boom-raising operation, wherein the command motor capacity calculation section is configured to reduce the command motor capacity when the boom-raising driving pressure is greater than a predetermined boom priority drive pressure during the performance of the slewing and boom-raising operation and wherein the command signal input section is configured to generate the capacity command signal based on the command motor capacity having been reduced.

8. The slewing hydraulic work machine according to claim 7 , wherein the command motor capacity calculation section is configured to increase the command motor capacity when the boom-raising driving pressure is less than a slewing priority drive pressure that is set at a value equal to or less than the boom priority drive pressure during the performance of the slewing and boom-raising operation and the command signal input section is configured to generate the capacity command signal based on the command motor capacity having been increased.

9. The slewing hydraulic work machine according to claim 8 , wherein the slewing priority drive pressure is less than the boom priority drive pressure, and wherein the command motor capacity calculation section is configured to cancel changing the command motor capacity in accordance with the boom-raising driving pressure when the boom-raising driving pressure is within a middle drive pressure range from the slewing priority drive pressure to the boom priority drive pressure during the performance of the slewing and boom-raising operation.

10. The slewing hydraulic work machine according to claim 8 , wherein the command motor capacity calculation section is configured to cancel changing the command motor capacity in accordance with the boom-raising driving pressure when the boom-raising driving pressure is less than a predetermined minimum drive pressure that is less than the slewing priority drive pressure.

11. The slewing hydraulic work machine according to claim 1 , further comprising a motor differential pressure detector that detects an effective differential pressure of the slewing motor and an allowable motor capacity determination section that determines an allowable motor capacity based on an allowable torque set for the slewing motor and the effective differential pressure detected by the motor differential pressure detector, wherein the command signal input section is configured to generate the capacity command signal for setting the slewing motor capacity to the allowable motor capacity when the command motor capacity calculated by the command motor capacity calculation section is greater than the allowable mo

Assignees

• Kobelco Constr Mach Co Ltd

Inventors

• Ueda Koji

Classifications

• F15B11/02

  Systems essentially incorporating special features for controlling the speed or actuating force of an output member · CPC title

• F15B11/046

  depending on the position of the working member · CPC title

• E02F9/22

  Hydraulic or pneumatic drives {(for dipper or bucket arm position control E02F3/43, for blade position control for graders E02F3/844; for turntables E02F9/121; for fork-lift trucks B66F9/22)} · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• E02F9/2235

  including an electronic controller · CPC title