Disclosed is a hydraulic power circuit for recycling a flow which is relieved to an operating oil tank when a pressure exceeding a preset pressure occurs at an operating apparatus operating by means of the hydraulic fluid of a hydraulic pump. A hydraulic power circuit for a construction machine according to the present invention comprises: first and second hydraulic pumps and a pilot pump; a first hydraulic actuator which is driven by the hydraulic fluid of the first hydraulic pump; a second hydraulic actuator which is driven by the hydraulic fluid of the second hydraulic pump; first and second operation levers; a first control valve for controlling hydraulic fluid which is supplied from the first hydraulic pump to the second hydraulic actuator at the time of switching; a second control valve for controlling hydraulic fluid which is supplied from the second hydraulic pump to the second hydraulic actuator at the time of switching; a main relief valve which is installed in the flow path of the first hydraulic pump and in a drain flow path which connects the flow path of the second hydraulic pump to the operating oil tank; and a flow sharing valve installed in the drain flow path between the main relief valve and the operating oil tank.

L'invention concerne un circuit de puissance hydraulique pour le recyclage d'un écoulement qui est libéré vers un réservoir d'huile de fonctionnement lorsqu'une pression dépassant une pression prédéfinie survient au niveau d'un appareil d'exploitation fonctionnant au moyen du fluide hydraulique d'une pompe hydraulique. Un circuit de puissance hydraulique, destiné à un engin de construction selon la présente invention, comprend : des première et seconde pompes hydrauliques et une pompe pilote; un premier actionneur hydraulique qui est entraîné par le fluide hydraulique de la première pompe hydraulique; un second actionneur hydraulique qui est entraîné par le fluide hydraulique de la seconde pompe hydraulique; des premier et second leviers de commande; une première soupape de commande permettant de commander le fluide hydraulique qui est fourni de la première pompe hydraulique au second actionneur hydraulique au moment de la commutation; une seconde soupape de commande permettant de commander le fluide hydraulique qui est fourni de la seconde pompe hydraulique au second actionneur hydraulique au moment de la commutation; un clapet de décharge principal qui est installé dans le trajet d'écoulement de la première pompe hydraulique et dans un trajet d'écoulement de drainage qui relie le trajet d'écoulement de la seconde pompe hydraulique vers le réservoir d'huile de fonctionnement; et un clapet de partage d'écoulement installé dans le trajet d'écoulement de drainage entre le clapet de décharge principal et le réservoir d'huile de fonctionnement.

유압펌프의 작동유에 의해 동작하는 작업장치에 설정압력을 초과하는 압력 발생시 작동유탱크로 릴리프되는 유량을 재활용하기 위한 유압회로를 개시한다. 본 발명에 따른 건설기계용 유압회로에 있어서, 제1,2유압펌프 및 파일럿펌프; 상기 제1유압펌프의 작동유에 의해 구동하는 제1유압액츄에이터; 상기 제2유압펌프의 작동유에 의해 구동하는 제2유압액츄에이터; 제1,2조작레버; 절환시 상기 제1유압펌프로부터 상기 제1유압액츄에이터에 공급되는 작동유를 제어하는 제1컨트롤밸브; 절환시 상기 제2유압펌프로부터 상기 제2유압액츄에이터에 공급되는 작동유를 제어하는 제2컨트롤밸브; 상기 제1유압펌프의 유로 및 상기 제2유압펌프의 유로를 작동유탱크에 연결하는 드레인유로에 설치되는 메인 릴리프밸브; 상기 메인 릴리프밸브와 상기 작동유탱크사이의 상기 드레인유로에 설치되는 유량공유밸브;를 구비하는 것을 특징으로 하는 건설기계용 유량 제어장치를 제공한다.