Hydraulic control device for controlling a boom-swing frame combined motion in an excavator

• US 7,275,369 B2
• Filed: 12/21/2005
• Issued: 10/02/2007
• Est. Priority Date: 12/22/2004
• Status: Expired due to Fees

• Current Assignee: Doosan Infracore Company Limited
• Original Assignee: Doosan Infracore Company Limited
• Inventors: Kim, Yong Chae
• Primary Examiner(s): LESLIE, MICHAEL S
• Application Number:
  US11/315,420
• Publication Number:
  US 20060130473A1
• Time in Patent Office: 650 Days
• Field of Search: 604/22, 604/26, 604/29, 604/30, 914/48, 915/16
• US Class Current: 60/422
• CPC Class Codes: E02F 9/2282 Systems using center bypass type changeover valves
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: E02F 9/26 Indicating devices E02F5/145 takes precedence
• CPC Class Codes: F15B 11/17 using two or more pumps
• CPC Class Codes: F15B 2211/20553 with pilot circuit, e.g. for controlling a swash plate
• CPC Class Codes: F15B 2211/30505 Non-return valves, i.e. check valves
• CPC Class Codes: F15B 2211/30565 having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
• CPC Class Codes: F15B 2211/30595 with additional valves between the groups of valves for multiple output members
• CPC Class Codes: F15B 2211/3116 the pump port being open in the centre position, e.g. so-called open centre
• CPC Class Codes: F15B 2211/353 Flow control by regulating means in return line, i.e. meter-out control
• CPC Class Codes: F15B 2211/50518 using pressure relief valves
• CPC Class Codes: F15B 2211/55 for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
• CPC Class Codes: F15B 2211/6355 having valve means
• CPC Class Codes: F15B 2211/7058 Rotary output members
• CPC Class Codes: F15B 2211/7128 the chambers being connected in parallel

Abstract

A hydraulic control device includes first and second pumps, a swing control spool, a boom first-speed control spool, a boom second-speed control spool, a swing motor, a boom cylinder, a pilot control valve, and a confluence line for merging the hydraulic flow from the boom second-speed control spool with that from the boom first-speed control spool. Provided on the confluence line is a swing priority valve having an orifice for variably reducing the hydraulic flow supplied to the boom cylinder through the confluence line. A swing priority control line is provided to interconnect a pressure receiving part of the swing priority valve and a swing control pilot pressure signal line of the pilot control valve in such a manner that an aperture area of the variable orifice of the swing priority valve is reduced in proportion to the magnitude of a swing control pilot pressure of the pilot control valve.

Claims

1. A hydraulic control device for controlling a boom-swing frame combined motion in an excavator, comprising first and second fluid pumps (P1, P2), a swing control spool (13) and a boom second-speed control spool (11B) respectively provided on parallel lines (16, 17) for receiving a hydraulic flow from the first pump (P1) via the parallel lines (16, 17), a boom first-speed control spool (11A) for receiving a hydraulic flow from the second pump (P2), a swing motor (1) actuated by the hydraulic flow supplied from the first pump (P1) through the swing control spool (13), a boom cylinder (3) actuated by the hydraulic flows supplied from the first and second pumps (P1, P2) through the boom second-speed control spool (11B) and the boom first-speed control spool (11A), a pilot control valve (24) for providing a pilot pressure to displace the swing control spool (13), the boom first-speed control spool (11A) and the boom second-speed control spool (11B), and a confluence line (25) for merging the hydraulic flow from the boom second-speed control spool (11B) with that from the boom first-speed control spool (11A), characterized by further comprising:

a swing priority valve (30) provided on the confluence line (25) and having a variable orifice (31) for variably reducing the hydraulic flow supplied to the boom cylinder (3) through the confluence line (25); and

a swing priority control line (27) interconnecting a pressure receiving part of the swing priority valve (30) and a swing control pilot pressure signal line of the pilot control valve (24) in such a manner that an aperture area of the variable orifice (31) of the swing priority valve (30) is reduced in proportion to the magnitude of a swing control pilot pressure of the pilot control valve (24).

2. The hydraulic control device as recited in claim 1, wherein the variable orifice (31) of the swing priority valve (30) comprises a variable throttling section (X) for reducing the aperture area in proportion to the magnitude of a swing control pilot pressure in the swing priority control line (27) and a bleed-off section (Y) formed contiguous to the variable throttling section (X) for keeping the aperture area constant.

3. The hydraulic control device as recited in claim 1, further comprising a selection switch (28) and a selection valve (29) provided on the swing priority control line (27) for selectively opening and shutting off the swing priority control line (27) in response to activation and deactivation of the selection switch (28).

4. The hydraulic control device as recited in claim 2, further comprising a selection switch (28) and a selection valve (29) provided on the swing priority control line (27) for selectively opening and shutting off the swing priority control line (27) in response to activation and deactivation of the selection switch (28).