Rotation control device and construction machine including rotation control device

Patent metadata

Field	Value
Publication number	US-9528245-B2
Application number	US-201314132704-A
Country	US
Kind code	B2
Filing date	Dec 18, 2013
Priority date	Dec 26, 2012
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

The invention provides a rotation control device capable of reducing a loss of a power of a hydraulic pump in a backward direction operation and also provides a construction machine including the same. The controller controls a capacity of the hydraulic pump such that, in a forward direction operation in which an operating direction detected by the operation sensor and a rotating direction detected by a rotation sensor coincide with each other, the capacity of the hydraulic pump is increased in accordance with an increase in the operation amount detected by an operation sensor, on the other hand, restricts the capacity of the hydraulic pump more in a backward direction operation, in which the operating direction detected by the operation sensor and the rotating direction detected by the rotation sensor are reverse to each other, than in the forward direction operation.

First claim

What is claimed is:

1. A rotation control device comprising:
a slewing motor driving a slewing body to rotate;
a hydraulic pump serving as a hydraulic pressure source of the slewing motor;
a pair of rotation hydraulic fluid paths connected to ports on both sides of the slewing motor for driving the slewing body in two directions;
a control valve provided between the respective rotation hydraulic fluid paths and the hydraulic pump and switching a supply destination of a hydraulic fluid, which is discharged from the hydraulic pump, between the respective rotation hydraulic fluid paths;
a pair of relief valves serving as brake valves respectively connected to the rotation hydraulic fluid paths;
rotation operating means for operating the control valve;
an operation detector detecting an operating direction and an operating amount of the rotation operating means;
a rotation direction detector for detecting a rotating direction of the slewing body; and
a controller controlling a discharge amount of the hydraulic pump such that in a forward direction operation in which the operating direction detected by the operation detector and the rotating direction detected by the rotation direction detector coincide with each other, the discharge amount of the hydraulic pump is increased in accordance with an increase in the operating amount detected by the operation detector, on the other hand, in a backward direction operation in which the operating direction detected by the operation detector and the rotating direction detected by the rotation direction detector are reverse to each other, the discharge amount of the hydraulic pump is restricted more than the discharge amount in the forward direction operation.

2. The rotation control device according to claim 1 , further comprising:
an unloading circuit for returning the hydraulic fluid from the hydraulic pump to a tank by being branched from a pump discharge path connecting the hydraulic pump and the control valve; and
an unloading valve provided at the unloading circuit and capable of adjusting a size of an opening,
wherein the controller adjusts the opening of the unloading valve to be smaller in accordance with an increase in the operating amount detected by the operation detector in the forward direction operation, on the other hand, adjusts the opening of the unloading valve to be larger in the backward direction operation than when the forward direction operation is carried out.

3. The rotation control device according to claim 2 , further comprising:
a check valve provided between a branch point of the unloading circuit in the pump discharge path and the control valve, and permitting a flow of the hydraulic fluid directed from the hydraulic pump to the control valve, while restricting a flow in a direction reverse thereto.

4. The rotation control device according to claim 1 , wherein the controller gradually reduces the discharge amount of the hydraulic pump to a set value by using a preset delay time since when the backward direction operation is detected.

5. A construction machine comprising:
a self-propelled lower propelling body;
an upper slewing body rotatably provided to the lower propelling body; and
the rotation control device according to claim 1 for rotating the upper slewing body as the slewing body.

6. A rotation control device comprising:
a slewing motor driving a slewing body to rotate;
a hydraulic pump serving as a hydraulic pressure source of the slewing motor;
a pair of rotation hydraulic fluid paths connected to ports on both sides of the slewing motor for driving the slewing body in two directions;
a control valve provided between the respective rotation hydraulic fluid paths and the hydraulic pump and switching a supply destination of a hydraulic fluid, which is discharged from the hydraulic pump, between the respective rotation hydraulic fluid paths;
a pair of relief valves serving as brake valves respectively connected to the rotation hydraulic fluid paths;
an operator actuatable valve providing an output to the control valve for operating the control valve;
an operation detector detecting an operating direction and an operating amount of the operator actuatable valve;
a rotation direction detector for detecting a rotating direction of the slewing body; and
control means for controlling a discharge amount of the hydraulic pump such that in a forward direction operation in which the operating direction detected by the operation detector and the rotating direction detected by the rotation direction detector coincide with each other, the discharge amount of the hydraulic pump is increased in accordance with an increase in the operating amount detected by the operation detector, on the other hand, in a backward direction operation in which the operating direction detected by the operation detector and the rotating direction detected by the rotation direction detector are reverse to each other, the discharge amount of the hydraulic pump is restricted more than the discharge amount in the forward direction operation.

Assignees

• Kobelco Constr Mach Co Ltd

Inventors

• Goto Naoki
• Ueda Koji
• Kamimura Yusuke

Classifications

• F15B2211/755

  Control of acceleration or deceleration of the output member · CPC title

• F15B2211/665

  Methods of control using electronic components · CPC title

• F15B2211/761

  Control of a negative load, i.e. of a load generating hydraulic energy · CPC title

• F15B11/048

  with deceleration control · CPC title

• F15B2211/20546

  variable capacity · CPC title