KR100576028B1 - Minimum flow control system of pump for excavator - Google Patents

Minimum flow control system of pump for excavator Download PDF

Info

Publication number
KR100576028B1
KR100576028B1 KR1020010086551A KR20010086551A KR100576028B1 KR 100576028 B1 KR100576028 B1 KR 100576028B1 KR 1020010086551 A KR1020010086551 A KR 1020010086551A KR 20010086551 A KR20010086551 A KR 20010086551A KR 100576028 B1 KR100576028 B1 KR 100576028B1
Authority
KR
South Korea
Prior art keywords
pump
valve
flow rate
signal
central control
Prior art date
Application number
KR1020010086551A
Other languages
Korean (ko)
Other versions
KR20030056347A (en
Inventor
이민희
김병수
Original Assignee
현대중공업 주식회사
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 현대중공업 주식회사 filed Critical 현대중공업 주식회사
Priority to KR1020010086551A priority Critical patent/KR100576028B1/en
Publication of KR20030056347A publication Critical patent/KR20030056347A/en
Application granted granted Critical
Publication of KR100576028B1 publication Critical patent/KR100576028B1/en

Links

Images

Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E02F9/2235—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps including an electronic controller
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2246—Control of prime movers, e.g. depending on the hydraulic load of work tools
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2285—Pilot-operated systems

Landscapes

  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Operation Control Of Excavators (AREA)
  • Control Of Positive-Displacement Pumps (AREA)

Abstract

본 발명은 펌프의 유량 가변제어가 가능한 굴삭기에 있어 작업대기시 동력손실을 최소화하기 위하여 펌프 사판각 및 펌프 입력 마력의 조절 등의 펌프제어를 함으로써 장비의 연료절감 및 내구성 향상시킬 수 있는 굴삭기 펌프 최소 유량 조절방법에 관한 것으로 굴삭기의 작업대기시 엔진 연료 손실을 최소화하기 위하여 엔진(E),가변용량형 펌프(P1),메인 콘트롤 밸브(70),중앙제어 컴퓨터(C),전자비례 감압밸브(1) 및 솔레노이드 밸브(2)를 구성하여 펌프의 최소 유량을 조절함에 있어서,네가티브 라인(3)과 솔레노이드 밸브(2)에 의해 제어되는 파이롯트 펌프(4)의 파이롯트 라인 사이에 셔틀밸브(5)를 설치하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터(C)의 신호로 솔레노이드 밸브(2)를 작동하고 셔틀밸브(5)에서 압력을 비교 센싱하여 펌프의 사판각을 최소로 작동케 하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터(C)에서 펌프 레귤레이터(60) 입력 토크를 조절하는 전자비례 감압밸브(1)에 신호를 가하여 펌프입력 토크를 최소로 제어하는 것을 특징으로 하는 굴삭기 펌프 최소 유량 조절방법.The present invention in the excavator that can control the variable flow rate of the pump in order to minimize the power loss during the operation of the pump control such as the adjustment of the pump swash plate angle and pump input horsepower to minimize the fuel saving and durability of the equipment pump The flow rate control method relates to the engine (E), the variable displacement pump (P1), the main control valve 70, the central control computer (C), the electronic proportional pressure reducing valve ( 1) and in configuring the solenoid valve 2 to regulate the minimum flow rate of the pump, the shuttle valve 5 between the negative line 3 and the pilot line of the pilot pump 4 controlled by the solenoid valve 2. To operate the solenoid valve (2) with the signal of the central control computer (C) receiving the signal of the working standby state, and compare the pressure at the shuttle valve (5) The pump input torque is controlled to a minimum by applying a signal to the electronic proportional pressure reducing valve (1) which controls the input voltage of the pump regulator 60 from the central control computer C which has the minimum operating and received the signal of the working standby state. How to adjust the minimum flow rate of excavator pump.

건설중장비,펌프유량,가변제어,셔틀밸브,솔레노이드 밸브Equipment under construction, pump flow rate, variable control, shuttle valve, solenoid valve

Description

굴삭기 펌프 최소 유량 조절방법 {Minimum flow control system of pump for excavator} Minimal flow control system of pump for excavator             

도 1 은 본 발명의 유압회로도 1 is a hydraulic circuit diagram of the present invention

도 2 는 종래의 유압회로도2 is a conventional hydraulic circuit diagram

<도면의 주요부분에 대한 부호의 설명><Description of the symbols for the main parts of the drawings>

(1) 전자비례 감압밸브 (2) 솔레노이드 밸브(1) Electronic proportional pressure reducing valve (2) Solenoid valve

(3) 네가티브 라인 (4) 파이롯트 펌프(3) Negative Line (4) Pilot Pump

(5) 셔틀밸브 (10) 메인 라인(5) Shuttle Valve (10) Main Line

(20) 메인스풀 (30) 바이패스 릴리프 밸브(20) Main Spool (30) Bypass Relief Valve

(40) 오리피스 (50) 펌프제어 라인(40) Orifice (50) Pump Control Line

(60) 펌프 레귤레이터 (70) 메인 컨트롤밸브(60) Pump Regulator (70) Main Control Valve

(E) 엔진 (P) 메인 펌프(E) Engine (P) Main Pump

(P1) 가변용량 펌프 (C) 중앙제어 컴퓨터(P1) Variable displacement pump (C) Central control computer

(Pia)(Pib) 포트       (Pia) (Pib) port

본 발명은 펌프의 유량 가변제어가 가능한 굴삭기에 있어 작업대기시 동력손실을 최소화하기 위하여 펌프 사판각 및 펌프 입력 마력의 조절 등의 펌프제어를 함으로써 장비의 연료절감 및 내구성 향상시킬 수 있는 굴삭기 펌프 최소 유량 조절방법에 관한 것이다.The present invention in the excavator that can control the variable flow rate of the pump in order to minimize the power loss during the operation of the pump control such as the adjustment of the pump swash plate angle and pump input horsepower to minimize the fuel saving and durability of the equipment pump It relates to a flow rate adjustment method.

종래의 굴삭기에서 작업대기시 엔진 연료손실을 최소화하기 위한 방법으로는 도 2 에 도시된 바와같이 엔진(E)으로부터 회전운동에너지를 이용하여 메인펌프(P)의 가변용량 펌프(P1)에서 작동유를 메인라인(10)을 통해 토출하는 한편 메인스풀(20)이 중립위치 포트(Pia) 또는 포트(Pib)를 통하여 아무런 신호를 받지 않을 경우에는 상기 메인라인(10)을 통한 유량은 바이패스 릴리프 밸브(30)를 통하여 탱크로 귀환하며 이와 동시에 오리피스(40)에서 형성된 압력이 펌프 제어라인(50)을 통하여 펌프 레귤레이터(60)로 전달되어 펌프의 사판각을 제어하여 토출유량을 감소시킨다.As a method for minimizing engine fuel loss during work standby in a conventional excavator, as shown in FIG. 2, the hydraulic fluid is supplied from the variable displacement pump P1 of the main pump P using rotational kinetic energy from the engine E. When the discharge through the main line 10 while the main spool 20 receives no signal through the neutral position port Pi or the port Pib, the flow rate through the main line 10 is a bypass relief valve. Returning to the tank through the 30 and at the same time the pressure formed in the orifice 40 is transmitted to the pump regulator 60 through the pump control line 50 to control the swash plate angle of the pump to reduce the discharge flow rate.

한편으로 작업을 하지 않는 신호를 중앙제어 컴퓨터(C)가 검출하여 엔진(E)의 회전수를 일정값으로 감소시킨다.On the other hand, the central control computer C detects a signal that does not work and reduces the rotation speed of the engine E to a constant value.

상기와 같은 종래의 유량 조절방법은 엔진(E),가변용량형 펌프(P1),메인 컨트롤 밸브(70) 및 중앙제어 컴퓨터(C)로 구성되어 작업대기시 엔진 연료 손실을 최 소화하기 위하여 엔진회전수 자동 감속장치를 적용하여 단지 엔진회전수 만 줄여줌으로써 완전한 펌프 토출유량 및 펌프 입력 토크의 최소화가 이루어지지 않아서 동력손실을 최소화 할 수 없는 문제점이 있었다. Conventional flow control method as described above is composed of an engine (E), a variable displacement pump (P1), the main control valve 70 and the central control computer (C) to minimize the engine fuel loss during work waiting engine By reducing the engine speed by applying the automatic speed reduction device, there was a problem that the power loss could not be minimized because the complete pump discharge flow rate and the pump input torque were not minimized.

따라서 본 발명은 상기한 종래의 문제점을 해결하기 위한 목적으로 창출된 것으로 굴삭기의 작업대기시 엔진 연료 손실을 최소화하기 위하여 엔진,가변용량형 밸브,중앙제어 컴퓨터,전자비례 감압밸브 및 솔레노이드 밸브를 구성하여 엔진회전수 뿐만 아니라 펌프 토출유량(사판각) 또는 펌프 입력 토크를 최소화 함으로써 공회전시의 동력손실을 최소화시킬 수 있는 굴삭기 펌프 최소 유량 조절방법을 제공하기 위한 것이다.
Therefore, the present invention was created for the purpose of solving the above-mentioned conventional problems, and in order to minimize the engine fuel loss during the standby operation of the excavator, the engine, variable displacement valve, central control computer, electromagnetic proportional pressure reducing valve and solenoid valve By minimizing the pump discharge flow rate (swash plate angle) or the pump input torque as well as the engine speed to provide an excavator pump minimum flow rate control method that can minimize the power loss during idle.

상기한 유량 조절방법을 제공하기 위하여 네가티브 라인과 솔레노이드 밸브에 의해 제어되는 파이롯트 라인 사이에 셔틀밸브를 설치하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터에서 나온 신호로 솔레노이드 밸브를 작동하고 셔틀밸브에서 압력을 비교 센싱하여 펌프의 사판각을 최소로 작동하게 하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터에서 펌프 레귤레이터 입력 토크를 조절하는 전자비례 감압밸브에 신호를 가하여 펌프입력 토크를 최소로 제어시킴으로써 굴삭기의 작업대기시 엔진 연료 손실을 최소화할 수 있는 유량 조절방법을 제공할 수 있는 것이다.In order to provide the above flow control method, a shuttle valve is installed between the negative line and the pilot line controlled by the solenoid valve, and the solenoid valve is operated by the signal from the central control computer receiving the signal of the standby state and the pressure at the shuttle valve By comparing and sensing the swash plate angle of the pump to the minimum, and controlling the pump input torque by applying a signal to the electronic proportional pressure reducing valve that regulates the pump regulator input torque from the central control computer that receives the signal of the working state, It is possible to provide a flow control method that can minimize engine fuel loss during work waiting.

이하 발명의 요지를 첨부된 도면에 연계시켜 그 구성과 작용을 상세히 설명하면 다음과 같다.Hereinafter, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

도 1 은 본 발명에 의한 굴삭기의 펌프 유량 제어하는 유압 회로도이다.1 is a hydraulic circuit diagram for controlling the pump flow rate of an excavator according to the present invention.

굴삭기의 작업대기시 엔진 연료 손실을 최소화하기 위하여 엔진(E),가변용량형 펌프(P1),메인 콘트롤 밸브(70),중앙제어 컴퓨터(C),전자비례 감압밸브(1) 및 솔레노이드 밸브(2)를 구성하여 펌프의 최소 유량을 조절함에 있어서,Engine (E), variable displacement pump (P1), main control valve (70), central control computer (C), electromagnetic proportional pressure reducing valve (1) and solenoid valve 2) in adjusting the minimum flow rate of the pump,

네가티브 라인(3)과 솔레노이드 밸브(2)에 의해 제어되는 파이롯트 펌프(4)의 파이롯트 라인 사이에 셔틀밸브(5)를 설치하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터(C)의 신호로 솔레노이드 밸브(2)를 작동하고 셔틀밸브(5)에서 압력을 비교 센싱하여 펌프의 사판각을 최소로 작동케 하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터(C)에서 펌프 레귤레이터(60) 입력 토크를 조절하는 전자비례 감압밸브(1)에 신호를 가하여 펌프입력 토크를 최소로 제어하는 방법이다.The solenoid is provided by a signal of the central control computer (C) which has a shuttle valve (5) installed between the negative line (3) and the pilot line of the pilot pump (4) controlled by the solenoid valve (2). Operate valve (2) and sense the pressure in shuttle valve (5) to minimize the swash plate angle of pump and increase input torque of pump regulator (60) from central control computer (C) which received the signal of working standby state. It is a method of controlling the pump input torque to a minimum by applying a signal to the electromagnetic proportional pressure reducing valve (1) to be adjusted.

이와같이된 본 발명은 굴삭기가 작업을 하지 않는 조건을 검출하는 중앙제어컴퓨터(C)가 엔진회전수를 제어함과 동시에 전자비례 감압밸브(1) 및 솔레노이드 밸브(2)를 제어하여 펌프의 토출유량 및 입력토크를 최소화하여 건설기계의 내구성을 향상시키고 연료를 절감할 뿐만아니라 환경보호를 할 수 있게한 것으로 작동 상태를 설명하면 다음과 같다.In the present invention as described above, the central control computer C, which detects the condition that the excavator does not work, controls the engine speed and simultaneously controls the electromagnetic proportional pressure reducing valve 1 and the solenoid valve 2 to discharge the pump. And by minimizing the input torque to improve the durability of the construction machinery and save fuel as well as to protect the environment as described the operation state as follows.

굴삭기가 작업을 하지 않는 조건(작업대기 중)을 중앙제어 컴퓨터(C)가 검출 하여 엔진(E)의 회전수를 일정값으로 감소시킴과 동시에 상기 중앙제어 컴퓨터(C)에서 펌프입력 토크를 제어하는 전자비례 감압밸브(1)에 신호를 가하여 펌프 레귤레이터(60)를 조정하여 펌프입력 토크를 최소로 감소시키는 한편,상기 중앙제어 컴퓨터(C)의 신호로 솔레노이드 밸브(2)를 작동하여 파이롯트 펌프(4)에서 형성된 압유와 메인 컨트롤밸브(70)의 오리피스(40)에서 센싱된 압력이 네가티브 라인(3)을 통하여 압력과 셔틀밸브(5)에서 비교하여 펌프 레귤레이터(60)의 사판각을 최소로 조정하는 것이다.The central control computer C detects the condition that the excavator is not working (during work waiting), reduces the rotation speed of the engine E to a constant value, and simultaneously controls the pump input torque from the central control computer C. By applying a signal to the proportional pressure reducing valve (1) to adjust the pump regulator 60 to reduce the pump input torque to a minimum, while operating the solenoid valve (2) by the signal of the central control computer (C) to operate the pilot pump The oil pressure formed in (4) and the pressure sensed at the orifice 40 of the main control valve 70 are compared with the pressure through the negative line 3 at the shuttle valve 5 to minimize the swash plate angle of the pump regulator 60. To adjust.

본 발명은 상술한 특정의 바람직한 실시예에 한정되지 아니하며, 청구범위에서 청구하는 본 발명의 요지를 벗어남이 없이 당해 발명이 속하는 기술분야에서 통상의 지식을 가진 자라면 누구든지 다양한 변형실시가 가능한 것은 물론이고, 그와 같은 변경은 청구범위 기재의 범위 내에 있게 된다. The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

그러므로 본 발명은 굴삭기의 작업대기시 엔진 연료 손실을 최소화하기 위하여 작업조건을 검출하는 중앙제어 컴퓨터가 엔진회전수 제어와 동시에 전자비례 감압밸브 및 솔레노이드 밸브를 제어하여 엔진회전수 뿐만 아니라 펌프 토출유량(사판각)과 펌프 입력 토크를 최소화 함으로써 공회전시의 동력손실을 최소화시킬 수 있어 연료를 절감할 뿐만아니라 내구성 향상과 환경친화적인 건설기계를 제공할 수 있는 효과가 있는 것이다.Therefore, in the present invention, the central control computer for detecting the operating conditions to minimize the engine fuel loss during the standby operation of the excavator controls the engine speed control and the electronic proportional pressure reducing valve and solenoid valve to control the pump discharge flow rate as well as the engine speed ( By minimizing the swash plate angle and the pump input torque, it is possible to minimize the power loss during idling, thereby saving fuel and providing durability and environmentally friendly construction machinery.

Claims (1)

굴삭기의 작업대기시 엔진 연료 손실을 최소화하기 위하여 엔진(E),가변용량형 펌프(P1),메인 콘트롤 밸브(70),중앙제어 컴퓨터(C),전자비례 감압밸브(1) 및 솔레노이드 밸브(2)를 구성하여 펌프의 최소 유량을 조절함에 있어서,Engine (E), variable displacement pump (P1), main control valve (70), central control computer (C), electromagnetic proportional pressure reducing valve (1) and solenoid valve 2) in adjusting the minimum flow rate of the pump, 네가티브 라인(3)과 솔레노이드 밸브(2)에 의해 제어되는 파이롯트 펌프(4)의 파이롯트 라인 사이에 셔틀밸브(5)를 설치하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터(C)의 신호로 솔레노이드 밸브(2)를 작동하고 셔틀밸브(5)에서 압력을 비교 센싱하여 펌프의 사판각을 최소로 작동케 하고 작업대기 상태의 신호를 받은 중앙제어 컴퓨터(C)에서 펌프 레귤레이터(60) 입력 토크를 조절하는 전자비례 감압밸브(1)에 신호를 가하여 펌프입력 토크를 최소로 제어하는 것을 특징으로 하는 굴삭기 펌프 최소 유량 조절방법.The solenoid is provided by a signal of the central control computer (C) which has a shuttle valve (5) installed between the negative line (3) and the pilot line of the pilot pump (4) controlled by the solenoid valve (2). Operate valve (2) and sense the pressure in shuttle valve (5) to minimize the swash plate angle of pump and increase input torque of pump regulator (60) from central control computer (C) which received the signal of working standby state. Excavator pump minimum flow rate control method characterized in that to control the pump input torque to a minimum by applying a signal to the electronic proportional pressure reducing valve (1) to adjust.
KR1020010086551A 2001-12-28 2001-12-28 Minimum flow control system of pump for excavator KR100576028B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020010086551A KR100576028B1 (en) 2001-12-28 2001-12-28 Minimum flow control system of pump for excavator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020010086551A KR100576028B1 (en) 2001-12-28 2001-12-28 Minimum flow control system of pump for excavator

Publications (2)

Publication Number Publication Date
KR20030056347A KR20030056347A (en) 2003-07-04
KR100576028B1 true KR100576028B1 (en) 2006-05-02

Family

ID=32214546

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020010086551A KR100576028B1 (en) 2001-12-28 2001-12-28 Minimum flow control system of pump for excavator

Country Status (1)

Country Link
KR (1) KR100576028B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20110054894A (en) * 2009-11-18 2011-05-25 볼보 컨스트럭션 이큅먼트 에이비 Hydraulic oil cooling system of construction equipment

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100621976B1 (en) * 2002-04-24 2006-09-13 볼보 컨스트럭션 이키프먼트 홀딩 스웨덴 에이비 construction heavy equipment of having boom down function
KR101328847B1 (en) * 2009-07-17 2013-11-13 현대중공업 주식회사 Negative Flow Control System for Mini Excavator
KR101861384B1 (en) * 2012-10-31 2018-07-06 현대건설기계 주식회사 Method For Driving Flow Rate Control Of Wheel Excavator
KR101978475B1 (en) * 2014-09-03 2019-05-15 현대건설기계 주식회사 Method for controlling work of excavator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20110054894A (en) * 2009-11-18 2011-05-25 볼보 컨스트럭션 이큅먼트 에이비 Hydraulic oil cooling system of construction equipment
KR101657248B1 (en) 2009-11-18 2016-09-19 볼보 컨스트럭션 이큅먼트 에이비 hydraulic oil cooling system of construction equipment

Also Published As

Publication number Publication date
KR20030056347A (en) 2003-07-04

Similar Documents

Publication Publication Date Title
US8024926B2 (en) Hydraulic circuit for heavy equipment
CN101517236B (en) Control system and method for pump output pressure control
US6976358B2 (en) Circuit for controlling discharge amount of hydraulic pump
JPH07127607A (en) Hydraulic device of work machine
JPH0568386B2 (en)
EP2589822B1 (en) Control device for a hydraulic pump of construction machinery
JP2001280256A (en) Pump control method and pump control device
KR100576028B1 (en) Minimum flow control system of pump for excavator
SE0002830D0 (en) Hydraulic system for controlling an attachment to a work machine such as a thumb attachment used on an excavator pivot shaft for an internal combustion engine
JP2578371B2 (en) Displacement control device for variable displacement pump
KR101648982B1 (en) Hydraulic pump control apparatus for construction machinery and hydraulic pump control method for the same
JP2007333017A (en) Energy saving device of construction machine
KR100640538B1 (en) Flow control apparatus of hydraulic pump for excavators
US7165397B2 (en) Anti-stall pilot pressure control system for open center systems
EP3470676B1 (en) Pump device
KR100656070B1 (en) Apparatus for controlling variable displaement hydraulic pumps of a wheel loader
EP0704623B1 (en) Delivery control device for hydraulic pumps
KR100953807B1 (en) Method of controlling power of hydraulic pump in an excavator and apparatus using the same
KR100762078B1 (en) Flow Control System of Hydraulic Pump for Excavators
JP3766972B2 (en) Hydraulic circuit for construction machinery
JP4003644B2 (en) Hydraulic control device for work machine
JP2009097579A (en) Hydraulic circuit of construction machine
JP4838085B2 (en) Engine control device for construction machinery
JP3714713B2 (en) Hydraulic control device
EP0821167A1 (en) Displacement controlling device for a variable displacement type hydraulic pump

Legal Events

Date Code Title Description
A201 Request for examination
E701 Decision to grant or registration of patent right
GRNT Written decision to grant
FPAY Annual fee payment

Payment date: 20110413

Year of fee payment: 7

FPAY Annual fee payment

Payment date: 20130416

Year of fee payment: 9

FPAY Annual fee payment

Payment date: 20160325

Year of fee payment: 11

LAPS Lapse due to unpaid annual fee