Hydraulic circuit for forklift

Patent metadata

Field	Value
Publication number	US-2017247238-A1
Application number	US-201515506166-A
Country	US
Kind code	A1
Filing date	Aug 25, 2015
Priority date	Aug 27, 2014
Publication date	Aug 31, 2017
Grant date	—

Abstract

The present disclosure relates to a hydraulic circuit for a forklift, and more particularly, to a hydraulic circuit for a forklift which is capable of preventing an engine from being stopped due to surge pressure that instantaneously occurs when a lift cylinder reaches an end stroke and thus cannot be operated any further when the lift cylinder is extended. According to the hydraulic circuit for a forklift according to the exemplary embodiment of the present disclosure, which is configured as described above, the accumulator is provided on the hydraulic line through which the working fluid is provided to the lift cylinder, and as a result, the accumulator may quickly absorb surge pressure when the surge pressure is produced in the lift cylinder or the hydraulic line.

First claim

1 . A hydraulic circuit for a forklift, the hydraulic circuit comprising:
an engine which produces power; a hydraulic pump which is operated by the power so as to suck a working fluid from an oil tank and discharge the working fluid; a control valve which is connected to the hydraulic pump through a first hydraulic line, and controls a flow rate and a flow direction of the working fluid discharged from the hydraulic pump; a lift cylinder which is connected to the control valve through a second hydraulic line, operated by the working fluid introduced through the second hydraulic line, and connected to the oil tank through a third hydraulic line so as to discharge the working fluid to the oil tank; a relief valve which is formed on a hydraulic line that connects the second hydraulic line and the third hydraulic line, has relief pressure set thereto, and is opened when abnormal high pressure higher than the relief pressure is formed in the second hydraulic line; and an accumulator which is connected to the first hydraulic line or the second hydraulic line, and absorbs surge pressure when the surge pressure is produced in the first hydraulic line or the second hydraulic line.

2 . The hydraulic circuit of claim 1 , wherein a plurality of accumulators is provided, the plurality of accumulators is connected to the first hydraulic line and the second hydraulic line, respectively, and any one of the plurality of accumulators absorbs the surge pressure when the surge pressure is produced in the first and second hydraulic lines.

3 . The hydraulic circuit of claim 1 , wherein the accumulator absorbs the surge pressure prior to a point in time at which the relief valve is opened.

4 . The hydraulic circuit of claim 3 , wherein free charge pressure of the accumulator is 10% to 20% of the relief pressure of the relief valve.

5 . The hydraulic circuit of claim 2 , wherein the accumulator absorbs the surge pressure prior to a point in time at which the relief valve is opened.

6 . The hydraulic circuit of claim 5 , wherein free charge pressure of the accumulator is 10% to 20% of the relief pressure of the relief valve.

Assignees

• Doosan Corp

Inventors

• Lee Byung Kwon

Classifications

• B66F9/22 Primary

  Hydraulic devices or systems · CPC title

• F15B13/0401

  Valve members; Fluid interconnections therefor · CPC title

• F15B13/024

  Pressure relief valves · CPC title

• F15B11/08

  with only one servomotor · CPC title

• F15B1/021

  used for damping · CPC title