본 발명에 의한 기어 펌프(1)는 내치 기어(10) 및 제 1 외치 기어(20)의 회전에 따라서 유체가 흡입되는 제 1 흡입 공간(L1)과 유체가 토출되는 제 1 토출 공간(H1)을 가짐과 아울러, 내치 기어(10) 및 제 2 외치 기어(30)의 회전에 따라서 유체가 흡입되는 제 2 흡입 공간(L2)과 유체가 토출되는 제 2 토출 공간(H2)을 갖고, 케이스 부재(50)는 흡입 공간(L1, L2)의 각각에 연통하는 흡입 공간 연통부(57)를 갖고, 플레이트 부재(80)는 토출 공간(H1, H2)의 각각에 연통하는 토출 공간 연통부(83)를 가져서 구성된다.
A gear pump comprises an internal gear (10), a first external gear (20) and a second external gear (30), a case member (50) having a one end side accommodation portion (52) for retaining these gears (10,20,30), an other end side accommodation portion (53) at other end side and a partition wall portion (54) therebetween, a cover member (70) and a plate member (80). A pump chamber (P) defined inside the internal gear (10) is divided into a first pump chamber (P1) which has a first intake-discharge space (L1) and a first discharge-intake space (H1), and a second pump chamber (P2)chich has a second intake-discharge space (L2) and a second discharge-intake space (H2). The plate member has a first communication path (81) and a second communication path (82) between the plate member (80) and the cover member (70). The one side communication passage (57) is communicated with the first communication path (81). Two penetrating holes (82b,82c) are formed on the plate member (80). An other side communication passage (82a), which communicate the two penetrating holes (82b,82c) with each other, is formed between the plate member (80) and the cover member (70).[Image]