Flow control valve for construction equipment, having floating function

Patent metadata

Field	Value
Publication number	US-10208456-B2
Application number	US-201315032926-A
Country	US
Kind code	B2
Filing date	Oct 31, 2013
Priority date	Oct 31, 2013
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

Disclosed is a hydraulic circuit for construction equipment, having a floating function for ground leveling work, which can be implemented by a main control valve. According to the present invention, provided is a flow control valve for construction equipment, having a floating function, comprising: a valve body having, formed therein, a supply path in communication with a pump path to which hydraulic oil is supplied from a hydraulic pump, and first and second actuator paths connected to a hydraulic cylinder driven by the hydraulic oil from the hydraulic pump; a spool switchably built into the valve body for, when switched, communicating the supply path into the first and second actuator paths so as to supply, to the hydraulic cylinder, the hydraulic oil from the hydraulic pump via the supply path and the first actuator path and return, to a tank path, the hydraulic oil discharged from the hydraulic cylinder via the second actuator path; a recycling path for supplying, to a small chamber of the hydraulic cylinder, a portion of the hydraulic oil returned from a large chamber of the hydraulic cylinder to the tank path and recycling the same; and a valve for floating conversion, installed at a predetermined position of the recycling path, wherein, in case of conversion to a floating state by application of pilot pressure to the valve for floating conversion, the large chamber and the small chamber of the hydraulic cylinder are communicated, and a path for supplying the hydraulic oil to the small chamber of the hydraulic cylinder and the recycling path are communicated so as to enable a bi-directional flow of the hydraulic oil.

First claim

The invention claimed is:

1. A flow control valve for construction equipment having a floating function, comprising:
a valve body defining
a supply passage communicating with a pump passage through which working fluid is supplied from a hydraulic pump and
first and second actuator passages connected to a hydraulic cylinder actuated by working fluid supplied from the hydraulic pump;

a spool switchably disposed within the valve body, wherein the spool is switched to allow the supply passage to communicate with the first or second actuator passage, such that working fluid from the hydraulic pump is supplied to the hydraulic cylinder through the supply passage and the first actuator passage, and working fluid discharged from the hydraulic cylinder returns to a tank passage through the second actuator passage;
a regeneration passage through which a portion of working fluid returning to the tank passage from a large chamber of the hydraulic cylinder is supplied to a small chamber of the hydraulic cylinder such that the portion of working fluid is regenerated; and
a floating switching valve disposed in the regeneration passage, wherein the floating switching valve is switched to a floating position in response to a pilot pressure applied thereto,
thereby causing the large chamber and the small chamber of the hydraulic cylinder to communicate with each other, and
causing the second actuator passage, through which working fluid is supplied to the small chamber of the hydraulic cylinder, and the regeneration passage to communicate with each other, such that an amount of working fluid is allowed to flow in both directions;
wherein the floating switching valve comprises:
a logic valve opening and closing the regeneration passage; and
a control valve disposed in a passage between a back pressure chamber of the logic valve and a working fluid tank,
wherein, when the control valve is switched in response to the pilot pressure applied thereto to switch the floating switching valve to the floating position, working fluid drains from the back pressure chamber of the logic valve, thereby allowing an amount of working fluid to flow to the regeneration passage from the second actuator passage through which working fluid is supplied to the small chamber of the hydraulic cylinder; and
wherein a drain line, through which the working fluid drains from the back pressure chamber of the logic valve, is connected to the tank passage within the valve body.

2. The flow control valve according to claim 1 , wherein a drain line, through which the working fluid drains from the back pressure chamber of the logic valve, is connected to a port outside of the valve body.

3. The flow control valve according to claim 1 , wherein the floating switching valve is disposed inside or outside of the valve body.

Assignees

• Volvo Constr Equip Ab

Inventors

• Ku Bon-Seuk

Classifications

• E02F9/2203 Primary

  Arrangements for controlling the attitude of actuators, e.g. speed, floating function · CPC title

• F15B11/15

  with special provision for automatic return · CPC title

• F15B13/021

  Valves for interconnecting the fluid chambers of an actuator · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• E02F9/2267

  Valves or distributors (position of valves arrangements on upper-structures E02F9/0875) · CPC title