Gear pump

Abstract

A gear pump having a suction port, first and second discharge ports, an inner rotor having external teeth, an outer rotor having internal teeth such that the number of the internal teeth is larger than that of the external teeth of the inner rotor, and inter-tooth chambers defined by the external teeth and the internal teeth. The first and second discharge ports are in communication with the inter-tooth chamber whose volume is decreased along with rotation of the inner rotor etc. An inter-tooth chamber which has been brought out of communication with the second discharge port is brought into communication with the suction port while the volume is decreasing. The volume of the inter-tooth chamber which has been brought out of communication with the second discharge port is increased after at least a part of the inter-tooth chamber has been brought into communication with the suction port.

Description

TECHNICAL FIELD[0001]The present disclosure relates to a gear pump that includes an inner rotor having a plurality of external teeth and an outer rotor having a plurality of internal teeth and disposed eccentrically with respect to the inner rotor.BACKGROUND ART[0002]There has hitherto been known a gear pump that includes an inner rotor having n external teeth, an outer rotor having (n+1) internal teeth meshed with the external teeth, and a casing formed with a suction port and a discharge port (see Patent Document 1, for example). In the gear pump, a first angle formed by a first line that connects between the center of rotation of the inner rotor and the tooth tip of the external teeth and a second line that connects between the center of rotation and a meshing portion of the external teeth is 1.4 times or more and 1.8 times or less a second angle formed by a third line that connects between the center of rotation and the tooth bottom of the external teeth and the second line. The...

AI Technical Summary

Benefits of technology

The present disclosure provides a gear pump that can prevent fluid containment in a cell with the smallest volume, which is brought out of communication with a discharge port and brought into communication with a suction port. This is achieved by decreasing the volume of the inter-tooth chamber that is brought out of communication with the discharge port and increasing the volume after it has been brought into communication with the suction port. This results in a rapid inflow of fluid into the inter-tooth chamber, which is brought out of communication with the discharge port, from a gap between the inner rotor and the outer rotor. This gear pump design prevents cavitation and ensures improved performance.

Problems solved by technology

Even if the configuration described in Patent Document 1 is adopted, however, it is still difficult to completely suppress an inflow of a fluid into the cell with the smallest volume, from which the fluid has been discharged to the discharge port, through a gap between the case and the rotors (a gap in the axial direction of the gear pump).

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