Internal gear pump

Abstract

An internal gear pump which has a crescent disposed between an outer rotor and an inner rotor having a trochoidal tooth profile, and which reduces vibrations caused by pulsations generated when the fluid is discharged. The internal gear pump has an outer rotor having internal teeth formed therein, an inner rotor disposed on the inner peripheral side of the outer rotor and having formed therein external teeth that mesh with the internal teeth, and a crescent disposed in a clearance between the outer rotor and the inner rotor. Pitch spacings of the external teeth of the inner rotor are formed as non-equal spacings, and pitch spacings of the internal teeth of the outer rotor correspond to the pitch spacings of the external teeth of the inner rotor.

1 . An internal gear pump, comprising: an outer rotor having internal teeth formed therein; an inner rotor disposed on the inner peripheral side of the outer rotor and having formed therein external teeth that mesh with the internal teeth; and a crescent disposed in a clearance between the outer rotor and the inner rotor, wherein
 pitch spacings of the external teeth of the inner rotor are formed as non-equal spacings, and pitch spacings of the internal teeth of the outer rotor correspond to the pitch spacings of the external teeth of the inner rotor.   
   
   
       2 . The internal gear pump according to  claim 1 , wherein a row of teeth with the number of teeth equal to the common divisor of the number of external teeth of the inner rotor and the number of internal teeth of the outer rotor is taken as a non-equal spacing pitch row, and identical non-equal spacing pitch rows are formed repeatedly. 
   
   
       3 . The internal gear pump according to  claim 2 , wherein the number of the non-equal spacing pitch rows is 3 or more. 
   
   
       4 . The internal gear pump according to  claim 1 , wherein the number of teeth of the inner rotor is 6 or more, and the number of teeth of the outer rotor is 9 or more. 
   
   
       5 . The internal gear pump according to  claim 1  wherein the tooth thicknesses of the external teeth and internal teeth in the non-equal spacing pitch rows are set to differ. 
   
   
       6 . The internal gear pump according to  claim 1 , wherein the tooth profile of the inner rotor is a trochoidal tooth profile. 
   
   
       7 . An internal gear pump, comprising: an outer rotor having internal teeth formed therein; an inner rotor disposed on the inner peripheral side of the outer rotor and having formed therein external teeth that mesh with the internal teeth; and a crescent disposed in a clearance between the outer rotor and the inner rotor, wherein
 tooth thickness dimensions of the external teeth of the inner rotor are formed to be non-uniform, and the tooth thicknesses of the internal teeth of the outer rotor correspond to the tooth thickness dimensions of the inner rotor.   
   
   
       8 . The internal gear pump according to  claim 7 , wherein the number of external teeth of the inner rotor and the number of internal teeth of the outer rotor are multiples of a common divisor of the number of external teeth and the number of internal teeth, a plurality of unit external tooth rows having the number of teeth at least equal to the greatest common divisor and also having different tooth thicknesses are provided in the external teeth of the inner rotor, and a plurality of unit internal tooth rows in which the internal teeth corresponding to the unit external tooth row of the inner rotor are arranged consecutively are provided in the outer rotor. 
   
   
       9 . The internal gear pump according to  claim 8 , wherein the number of unit external tooth rows of the inner rotor is 3 or more. 
   
   
       10 . The internal gear pump according to  claim 7 , wherein the number of teeth of the inner rotor is 6 or more, and the number of teeth of the outer rotor is 9 or more. 
   
   
       11 . The internal gear pump according to  claim 7 , wherein the tooth profile of the inner rotor is a trochoidal tooth profile. 
   
   
       12 . The internal gear pump according to  claim 7 , wherein a pitch angle of the external teeth of the inner rotor is formed to be non-uniform, and a pitch angle of the internal teeth of the outer rotor corresponds to the pitch angle of the external teeth. 
   
   
       13 . The internal gear pump according to  claim 8 , wherein a pitch angle of the external teeth of the unit external tooth row of the inner rotor is formed to be non-uniform, and a pitch angle of the internal teeth of the unit internal tooth row of the outer row corresponds to the pitch angle of the external teeth of the unit external tooth row. 
   
   
       14 . The internal gear pump according to  claim 2 , wherein the number of teeth of the inner rotor is 6 or more, and the number of teeth of the outer rotor is 9 or more. 
   
   
       15 . The internal gear pump according to  claim 2 , wherein the tooth thicknesses of the external teeth and internal teeth in the non-equal spacing pitch rows are set to differ. 
   
   
       16 . The internal gear pump according to  claim 2 , wherein the tooth profile of the inner rotor is a trochoidal tooth profile. 
   
   
       17 . The internal gear pump according to  claim 8 , wherein the number of teeth of the inner rotor is 6 or more, and the number of teeth of the outer rotor is 9 or more. 
   
   
       18 . The internal gear pump according to  claim 8 , wherein the tooth profile of the inner rotor is a trochoidal tooth profile. 
   
   
       19 . The internal gear pump according to  claim 8 , wherein a pitch angle of the external teeth of the inner rotor is formed to be non-uniform, and a pitch angle of the internal teeth of the outer rotor corresponds to the pitch angle of the external teeth. 
   
   
       20 . The internal gear pump according to  claim 9 , wherein a pitch angle of the external teeth of the unit external tooth row of the inner rotor is formed to be non-uniform, and a pitch angle of the internal teeth of the unit internal tooth row of the outer row corresponds to the pitch angle of the external teeth of the unit external tooth row.