Hydraulic control device of an excavator with improved loading performance on a slope

• US 7,356,991 B2
• Filed: 12/15/2005
• Issued: 04/15/2008
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: HD Hyundai Infracore Co., Ltd.
• Original Assignee: Doosan Infracore Company Limited
• Inventors: Sohn, Won Sun, Kim, Hyeong Ho
• Primary Examiner(s): LOPEZ, FRANK D
• Application Number:
  US11/305,772
• Publication Number:
  US 20060179691A1
• Time in Patent Office: 852 Days
• Field of Search: 604/21, 604/22, 915/11
• US Class Current: 60/421
• CPC Class Codes: E02F 9/2037 Coordinating the movements of the implement and of the frame
• CPC Class Codes: E02F 9/2242 including an electronic controller
• CPC Class Codes: E02F 9/2282 Systems using center bypass type changeover valves
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• 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 9/265 with follow-up actions (e.g. control signals sent to actuate the work tool)
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/30595 with additional valves between the groups of valves for multiple output members
• CPC Class Codes: F15B 2211/40515 with variable throttles or orifices
• CPC Class Codes: F15B 2211/41509 being connected to a pressure source and a directional control valve
• CPC Class Codes: F15B 2211/6303 using input signals
• CPC Class Codes: F15B 2211/665 Methods of control using electronic components
• CPC Class Codes: F15B 2211/6654 Flow rate control
• CPC Class Codes: F15B 2211/6658 Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode
• CPC Class Codes: F15B 2211/7058 Rotary output members
• CPC Class Codes: F15B 2211/7135 Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
• CPC Class Codes: F15B 2211/7142 the output members being arranged in multiple groups
• CPC Class Codes: F15B 2211/781 one or more output members having priority
• CPC Class Codes: F15B 2211/85 Control during special operating conditions

Abstract

A hydraulic control device of an excavator is provided for controlling combined operation of boom-raising and swing on a slope. A swing priority valve (20) is provided on a pressured fluid supply line (8) that connects a first hydraulic pump (1) to a boom high-speed control valve (7). If an excavator performs its tasks on a slope, the swing priority valve (20) is automatically shifted under a control of an electronic controller (28) into a throttling position to thereby restrict hydraulic flow through the boom high-speed control valve (7) so that an increased amount of hydraulic flow can be supplied to a swing motor (14), thus increasing a swing operating pressure more rapidly than a boom operating pressure and consequently facilitating combined operation of boom-raising and swing on a slope.

Claims

1. A hydraulic control device of an excavator comprising a first hydraulic pump (1), a second hydraulic pump (2), a swing control valve (6) in fluid communication with the first hydraulic pump (1) for controlling hydraulic flow from the first hydraulic pump (1) to a swing motor (14), a boom high-speed control valve (7) disposed at downstream of the swing control valve (6) and in fluid communication with the first hydraulic pump (1) via a pressured fluid supply line (8) for controlling hydraulic flow from the first hydraulic pump (1) to boom cylinders (15), and a boom low-speed control valve (11) for controlling hydraulic flow from the second hydraulic pump (2) to the boom cylinders (15), further comprising:

a working-on-slope detecting means (27) for detecting a tilt angle of the excavator and outputting a working-on-slope signal if the tilt angle detected is greater than a predetermined value; and

a swing priority valve (20) provided on the pressured fluid supply line (8) for the boom high-speed control valve (7) and throttling the hydraulic flow rate supplied to the boom high-speed control valve (7) from the first hydraulic pump (1), thereby relatively increasing the hydraulic flow rate to the swing control valve (6), in case of the working-on-slope signal being provided from the working-on-slope detecting means (27) and at the same time a swing control pilot pressure (SW1,SW2) for shifting the swing control valve (6) being provided thereto.

2. The device as recited in claim 1, further comprising a swing priority control line (23) for delivering a swing control pilot pressure to the swing priority valve (20), and

a selector valve (25) provided on the swing priority control line (23) to open the swing priority control line in case the working-on-slope signal is provided from the working-on-slope detecting means (27) or connect the swing priority control line (23) to a tank in case of no working-on-slope signal from the working-on-slope detecting means (27).

3. The device as recited in claim 2, wherein the working-on-slope detecting means (27) comprises a level for detecting the tilt angle of the excavator and generating the working-on-slope signal if the tilt angle detected is greater than a predetermined value.