INTERNAL GEAR PUMP

PROBLEM TO BE SOLVED: To provide a variable displacement type internal gear pump capable of preventing reduction in pump efficiency.SOLUTION: The internal gear pump includes an inner rotor 3, an outer rotor 4, a guide means B which swings the outer rotor 4 along a predetermined locus, and a pump housing A. In the interproximal space S which is formed between the inner rotor 3 and the outer rotor 4, a maximum interproximal space Sa is formed on a first partitioning part 14 at the initial position. The outer rotor 4 is swung from the initial position by the guide means B to move the maximum interproximal space Sa over a suction port 12, and to position the interproximal space S adjacent to the front side in the rotor rotating direction on the first partitioning part 14. The interproximal space S positioned on the first partitioning part 14 does not communicate with the maximum interproximal space Sa adjacent to the rear side in the rotor rotating direction, but communicates with the interproximal space S adjacent to the front side in the rotor rotating direction.