Swing control system for construction machines

Patent metadata

Field	Value
Publication number	US-9540789-B2
Application number	US-201314765787-A
Country	US
Kind code	B2
Filing date	Feb 6, 2013
Priority date	Feb 6, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

The disclosed invention relates to a swing control system for construction machines and is useful in a construction equipment in which the shaking or jerking movement of the upper swing structure due to the moment of inertia thereof is controlled by a simple electrical hydraulic control system so that although the swing manipulation is abruptly and repeatedly performed during the excavation or dumping operation, an operator can control the soft swing start/stop of the upper swing structure in the swing operation of construction machine, thereby improving manipulability and work efficiency of the work apparatus.

First claim

The invention claimed is:

1. A swing control system for construction machines, comprising: a hydraulic pump;
a swing motor driven by a hydraulic fluid supplied from the hydraulic pump and configured to swing an upper swing structure;
a swing control valve installed between the hydraulic pump and the swing motor, and configured to control the flow rate of the hydraulic fluid supplied and returned to the swing motor via a pair of hydraulic lines;
swing manipulation means configured to apply a spool shift signal corresponding to a manipulated variable of an operator to the swing control valve;
a shuttle valve installed on a relief line branched off from the hydraulic lines, and configured to select a higher pressure of the pressures of the hydraulic lines and drain a hydraulic fluid of the selected hydraulic line having the higher pressure to the relief line;
a relief valve installed on the relief line at the downstream side of the shuttle valve, and configured to control a required flow rate for a soft swing start to drain the hydraulic fluid through a first cutoff valve to a hydraulic tank, when the first cutoff valve is opened during swing start acceleration;
a first cutoff valve installed between the shuttle valve and the relief valve, and configured to selectively control the required flow rate for the soft swing start through the shuttle valve during swing start acceleration;
a second cutoff valve installed on a connection line branched off from the pair of hydraulic lines, and configured to selectively control a required flow rate for a soft swing stop on the connection line during swing stop deceleration;
a pair of pressure detecting means configured to sense the signal pressure provided to the swing control valve to shift or switch a spool; and
an electric controller electrically connected to the relief valve, the first cutoff valve, the second cutoff valve, and the pressure sensors, the electric controller being configured to determine whether the upper swing structure is in the soft swing start or stop, based on a potential pressure difference between the pressure detecting means, an inertial transform function and a derivative function operated by a predetermined algorithm, and selectively output valve control signals for controlling the valves during the swing start acceleration and the swing stop deceleration.

2. The swing control system for construction machines according to claim 1 , wherein the inertial transform function of the electric controller provides a smoother signal from almost square wave signal of the pressure detecting means, which is expressed by an equation,

Ut
=

K

Ts
-
1

,

wherein T is the machine/bucket size, and K is the pressure/valves voltages.

3. The swing control system for construction machines according to claim 1 , wherein the derivative function is applied to recognize the soft swing start or the soft swing stop, which is expressed by an equation U 1 (t)=Udt.

4. The swing control system for construction machines according to claim 1 , wherein the electric controller outputs the valve control signal continuously until it is determined that the swing start operation or stop operation is terminated.

5. The swing control system for construction machines according to claim 2 , wherein the electric controller outputs the valve control signal discontinuously at a certain interval time in the swing start operation or swing stop operation.

6. The swing control system for construction machines according to claim 1 , wherein the pressure detecting means includes a pressure sensor.

7. The swing control system for construction machines according to claim 1 , further comprising a variable throttle valve installed on the connection line.

8. The swing control system for construction machines according to claim 7 , wherein the swing manipulation means includes a hydraulic joystick.

9. The swing control system for construction machines according to claim 8 , wherein the swing manipulation means includes an electric joystick.

10. A construction machine having a lower traveling structure, an upper swing structure and a work apparatus attached to the upper swing structure, the upper swing structure mounted on the lower traveling structure to be swiveled, the work apparatus including a bucket, an arm and a boom pivotally connected on the upper swing structure, comprising:
a hydraulic pump;
a swing motor driven by a hydraulic fluid supplied from the hydraulic pump and configured to swing an upper swing structure;
a swing control valve installed between the hydraulic pump and the swing motor, and configured to control the flow rate of the hydraulic fluid supplied and returned to the swing motor via a pair of hydraulic lines;
swing manipulation means configured to apply a spool shift signal corresponding to a manipulated variable of an operator to the swing control valve;
a shuttle valve installed on a relief line branched off from the hydraulic lines, and configured to select a higher pressure of the pressures of the hydraulic lines and drain a hydraulic fluid of the selected hydraulic line having the higher pressure to the relief line;
a relief valve installed on the relief line at the downstream side of the shuttle valve, and configured to control a required flow rate for a soft swing start to drain the hydraulic fluid through a first cutoff valve to a hydraulic tank, when the first cutoff valve is opened during swing start acceleration;
a first cutoff valve installed between the shuttle valve and the relief valve, and configured to selectively control the required flow rate for the soft swing start through the shuttle valve during swing start acceleration;
a second cutoff valve installed on a connection line branched off from the pair of hydraulic lines, and configured to selectively control a required flow rate for a soft swing stop on the connection line during swing stop deceleration;
a pair of pressure detecting means configured to sense the signal pressure provided to the swing control valve to shift or switch a spool; and
an electric controller electrically connected to the relief valve, the first cutoff valve, the second cutoff valve, and the pressure sensors, the electric controller being configured to determine whether the upper swing structure is in the soft swing start or stop, based on a potential pressure difference between the pressure detecting means, an inertial transform function and a derivative function operated by a predetermined algorithm, and selectively output valve control signals for controlling the valves during the swing start acceleration and the swing stop deceleration.

11. The construction machines according to claim 10 , wherein the inertial transform function of the electric controller provides a smoother signal from almost square wave signal of the pressure detecting means, which is expressed by an equation,

Ut
=

K

Ts
-
1

,

wherein T is the machine/bucket size, and K is the pressure/valves voltages; and
the derivative function is applied to recognize the soft swing sta

Assignees

• Volvo Constr Equip Ab

Inventors

• Urbanowicz Marek

Classifications

• F15B11/048

  with deceleration control · CPC title

• F15B11/042

  by means in the feed line {, i.e. "meter in"}(F15B11/046, F15B11/05 take precedence) · CPC title

• E02F3/32

  working downwardly and towards the machine, e.g. with backhoes · CPC title

• E02F9/2214

  for reducing the shock generated at the stroke end · CPC title

• E02F9/123 Primary

  Drives or control devices specially adapted therefor (E02F9/125 and E02F9/128 take precedence) · CPC title