| US 7,500,360 B2 | ||
| Hydraulic driving system of construction machinery | ||
| Tsutomu Udagawa, Ibaraki-ken (Japan); Kazuo Takiguchi, Ibaraki-ken (Japan); Masami Ochiai, Atsugi (Japan); Takashi Yagyuu, Ushiku (Japan); Yukihiko Sugiyama, Tsuchiura (Japan); and Mitsuo Aihara, Ibaraki-ken (Japan) | ||
| Assigned to Hitachi Constuction Machinery Co., Ltd., Tokyo (Japan) | ||
| Appl. No. 10/499,307 PCT Filed Aug. 29, 2003, PCT No. PCT/JP03/11039 § 371(c)(1), (2), (4) Date Jun. 18, 2004, PCT Pub. No. WO2004/022858, PCT Pub. Date Mar. 18, 2004. |
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| Claims priority of application No. 2002-259582 (JP), filed on Sep. 05, 2002; and application No. 2003-297583 (JP), filed on Aug. 21, 2003. | ||
| Prior Publication US 2005/0175485 A1, Aug. 11, 2005 | ||
| Int. Cl. E02F 9/00 (2006.01); E02F 9/20 (2006.01); F15B 11/00 (2006.01) | ||
| U.S. Cl. 60—421 [60/484; 60/486] | 26 Claims |
| 1. A hydraulic drive system for a construction machine comprising a travel body, a swing body swingably mounted onto said
travel body, and a multi-articulated front operating mechanism coupled to said swing body in a vertically angularly movable
manner and made up of a boom and a bucket, wherein said hydraulic drive system comprises:
a first hydraulic pump and a second hydraulic pump driven by prime movers;
a plurality of hydraulic cylinders including a boom hydraulic cylinder, an arm hydraulic cylinder, and a bucket hydraulic
cylinder supplied with hydraulic fluids delivered from said first hydraulic pump and said second hydraulic pump to drive said
boom, said arm, and said bucket, respectively:
a plurality of directional flow control valves for controlling respective flows of the hydraulic fluid supplied from said
first hydraulic pump to said plurality of hydraulic cylinders;
a common high-pressure line having one side connected to the delivery side of said second hydraulic pump and the other side
extended to the side of said front operating mechanism;
a boom branch line branched from said common high-pressure line and connected on the side opposite to the branched side to
a rod pushing-side chamber of said boom hydraulic cylinder;
a boom inflow control valve disposed near a branch position at which said boom branch line is branched from said common high-pressure
line, and controlling a flow of a hydraulic fluid supplied from said common high-pressure line to the rod pushing-side chamber
of said boom hydraulic cylinder;
an arm branch line branched from said common high-pressure line at a position downstream of the branch position of said boom
branch line and connected on the side opposite to the branched side to a rod pushing-side chamber of said arm hydraulic cylinder;
an arm inflow control valve disposed near a branch position at which said arm branch line is branched from said common high-pressure
line, and controlling a flow of a hydraulic fluid supplied from said common high-pressure line to the rod pushing-side chamber
of said arm hydraulic cylinder;
a bucket branch line branched from said common high-pressure line at a position downstream of the branch position of said
boom branch line and connected on the side opposite to the branched side to a rod pushing-side chamber of said bucket hydraulic
cylinder; and
a bucket inflow control valve disposed near the branch position (D2) at which said bucket branch line is branched from said
common high-pressure line, and controlling a flow of a hydraulic fluid supplied from said common high-pressure line to the
rod pushing-side chamber of said bucket hydraulic cylinder,
said hydraulic system being configured such that when said boom hydraulic cylinder, said arm hydraulic cylinder and said bucket
hydraulic cylinder are operated to extend, the hydraulic fluid from said first hydraulic pump is supplied to said rod pushing-side
chambers of said boom, arm and bucket hydraulic cylinders through said plurality of directional flow control valves, respectively,
and the hydraulic fluid from said second hydraulic pump is supplied to said rod pushing-side chambers of said boom, arm and
bucket hydraulic cylinders through said common high-pressure line, said boom branch line, said arm branch line and said bucket
branch line and further said boom inflow control valve, said arm inflow control valve and said bucket inflow control valve,
respectively, and being joined with the hydraulic fluid from said first hydraulic pump, while the fluids discharged from the
rod drawing-side chambers of said boom, arm and bucket hydraulic cylinders are returned to said reservoir only through said
plurality of directional flow control valves, respectively,
wherein:
said inflow control valves are all disposed together in one control valve unit.
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