Internal gear pump

Abstract

An internal gear pump for delivering a fluid, in particular one of the gerotor pump type, having a driven gear wheel, a rotatable annular gear interacting with the gear wheel, and a substantially cylindrical housing, in which the gear wheel and the annular gear are arranged. The housing has a base portion, an annular portion and a cover portion, the base portion having a pressure port, which forms a delivery chamber of the pump or opens into the latter. A thrust ring is arranged between the gear wheel and the annular gear on the one hand and the cover portion of the housing on the other. At least one connecting passage on or in the housing of the pump extends from the delivery chamber of the pump up to a gap between the thrust ring and the cover portion of the housing, in order to carry fluid from the delivery chamber into the gap.

1 . A gear pump for delivering a fluid, comprising:
 a driven gear wheel;   a rotatable annular gear operatively communicating with the driven gear wheel;   a housing in which the driven gear wheel and the rotatable annular gear are arranged, the housing comprising a base portion, an annular portion and a cover portion, the base portion having a pressure port which forms a fluid delivery chamber;   a thrust ring arranged between the driven gear wheel and the rotatable annular gear and also the driven gear wheel and the cover portion;   a gap formed between the thrust ring and the cover portion; and   at least one fluid connecting passage extending from the fluid delivery chamber up to the gap in order to carry fluid from the delivery chamber into the gap.   
     
     
         2 . The gear pump of  claim 1 , wherein the connecting passage comprises at least one connecting groove which extends along the inner circumference of the annular portion of the housing. 
     
     
         3 . The gear pump of  claim 2 , wherein the connecting groove along the inner circumference of the annular portion is aligned parallel to the axis of rotation of the rotatable annular gear. 
     
     
         4 . The gear pump of  claim 1 , wherein the connecting passage comprises a connecting groove which extends from the delivery chamber of the pump along the base portion of the housing. 
     
     
         5 . The gear pump of  claim 1 , wherein the connecting passage opens into an annular groove which extends circumferentially along a transition between the annular portion and the cover portion of the housing and along the thrust ring. 
     
     
         6 . The gear pump of  claim 1 , wherein the cover portion of the housing comprises at least one distribution groove which extends radially inward on the inside surface of the cover portion. 
     
     
         7 . The gear pump of  claim 6 , wherein the distribution groove of the cover portion extends radially inward from the outer circumference of the cover portion to a central aperture of the cover portion. 
     
     
         8 . The gear pump of  claim 1 , wherein the thrust ring comprises at least one distribution groove which on the side of the thrust ring facing the cover portion of the housing extends radially inward from the outer circumference of the thrust ring. 
     
     
         9 . The gear pump of  claim 8 , wherein the distribution groove of the thrust ring extends radially inward from the outer circumference of the thrust ring to a central aperture of the thrust ring. 
     
     
         10 . The gear pump of  claim 1 , wherein the surface of the thrust ring facing the cover portion of the housing is one of tapered, truncated cone shape, and convexly curved. 
     
     
         11 . The gear pump of  claim 1 , wherein the housing comprises an outlet port configured to conduct a proportion of the fluid, carried out of the delivery chamber towards the gap, to another component to thereby lubricate the component. 
     
     
         12 . The gear pump of  claim 1 , wherein the thrust ring extends in one piece in a radial direction between the driven gear wheel and the rotatable annular gear. 
     
     
         13 . The gear pump of  claim 1 , wherein the thrust ring is rotationally fixed to the annular gear. 
     
     
         14 . The gear pump of  claim 1 , wherein the rotatable annular gear and the thrust ring are integrally formed. 
     
     
         15 . A gear pump for a gerotor pump, the gear pump comprising:
 a gear wheel which is rotatable about a first axis;   an annular gear which is rotatable about a second axis;   a thrust ring rotationally fixed to the annular gear;   a housing which houses the gear wheel, the annular gear and the thrust ring, the housing having a fluid delivery chamber and a cover portion;   a gap formed between the thrust ring and the cover portion; and   a fluid connecting passage in the housing through which fluid flows from the fluid delivery chamber to the gap to thereby form a hydrodynamic lubricating film in the gap which reduces operational friction between the thrust ring and the cover portion.   
     
     
         16 . The gear pump of  claim 15 , wherein the fluid connecting passage comprises:
 a first connecting groove extending radially and in communication with the fluid delivery chamber;   a second connecting groove extending axially and in communication with the first connecting groove; and   a third connecting groove extending radially and in communication with the second connecting groove and the gap.   
     
     
         17 . The gear pump of  claim 15 , wherein the thrust ring has a plurality of distribution grooves on a surface thereof which faces the gap and which are configured to distribute the fluid into the gap. 
     
     
         18 . The gear pump of  claim 17 , wherein the plurality of distribution grooves extend from an outer circumference to an inner circumference of the thrust ring portion. 
     
     
         19 . The gear pump of  claim 17 , wherein the plurality of distribution grooves extend from an outer circumference of the thrust ring portion to a predetermined distance from the inner circumference of the thrust ring portion. 
     
     
         20 . A gear pump comprising:
 a gear wheel;   an annular gear;   a thrust ring;   a housing having a fluid delivery chamber and a cover portion configured for placement such that a gap is formed between the thrust ring and the cover portion; and   a fluid connecting passage through a fluid flows from the fluid delivery chamber to the gap to thereby form a hydrodynamic lubricating film in the gap which reduces operational friction between the thrust ring and the cover portion,   wherein:
 the fluid connecting passage has a first connecting groove in communication with the fluid delivery chamber, a second connecting groove in communication with the first connecting groove, and a third connecting groove in communication with the second connecting groove and the gap, and 
 the thrust ring has a plurality of distribution grooves on a surface thereof which faces the gap and which are configured to distribute the fluid into the gap.