Rotating pump

Abstract

A rotating pump includes an outer and an inner rotor disposed in a casing with a gap between the casing and the outer rotor. The rotating pump also includes a first and a second sealing member in the casing to define a low-pressure region and a high-pressure region within the gap. Each of the first and second sealing members is made up of a seal functioning portion and an elastically pressing portion. The seal functioning portion includes a resinous member and a deformation-suppressing member. The resinous member contacts the outer rotor and a low-pressure side inner surface of the casing to establish a difference in pressure between the low-pressure region and the high-pressure region. The deformation-suppressing member works to stop the resinous member from deforming undesirably. This minimizes the risk of breakage of the resinous member and enables the rotating pump to discharge the fluid at an increased pressure.

What is claimed is: 
     
         1 . A rotating pump comprising:
 a drive shaft;   a rotor assembly made up of an outer rotor and an inner rotor, the outer rotor having inner teeth formed on an inner periphery thereof, the inner rotor having outer teeth formed on an outer periphery thereof and being rotated by the drive shaft around an axis defined by the drive shaft, the outer teeth meshing with the inner teeth of the outer rotor to define a plurality of cavities;   a casing in which the drive shaft is installed, the casing including a rotor chamber in which the rotor assembly is mounted to be rotatable with a gap formed between an inner peripheral surface of the casing which faces the outer rotor and an outer peripheral surface of the outer rotor, the casing having an inlet port from which fluid is sucked into the rotor assembly and an outlet port from which the fluid is discharged with rotation of the rotor assembly;   a first and a second recess formed in the inner peripheral surface of the casing which is exposed to the gap; and   a first and a second sealing member which are disposed in the first and second recesses, respectively, to define within the gap a low-pressure region leading to the inlet port and a high-pressure region leading to the outlet port, each of the first and second sealing members being made up of a seal functioning portion and an elastically pressing portion, the seal functioning portion being placed in contact with the outer periphery of the outer rotor and a low-pressure side surface that is a portion of an inner wall surface of a corresponding one of the first and second recesses which is closer to the low-pressure region than to the high-pressure region to establish a difference in pressure between the low-pressure region and the high-pressure region, the elastically pressing portion being located closer to a bottom of a corresponding one of the first and second recesses than the seal functioning portion is and working to press the seal functioning portion against the outer periphery of the outer rotor, the seal functioning portion including a resinous member and a deformation-suppressing member, the resinous member being placed in contact with the outer periphery of the outer rotor and the low-pressure side surface of the inner wall surface of a corresponding one of the first and second recesses to establish the difference in pressure between the low-pressure region and the high-pressure region, the deformation-suppressing member being made of material which is more rigid than that of the resinous member and located closer to the low-pressure region than the resinous member is, a boundary between a surface of the deformation-suppressing member which faces the low-pressure side surface and a surface of the resinous member which faces the low-pressure side surface being located inside a corresponding one of the recesses.   
     
     
         2 . A rotating pump as set forth in  claim 1 , wherein the deformation-suppressing member of the seal functioning portion has a dimension which is smaller than that of the rotor chamber in a direction parallel to an axis of rotation of the outer rotor. 
     
     
         3 . A rotating pump as set forth in  claim 1 , wherein the resinous member of the seal functioning portion has a dimension which is greater than that of the rotor chamber in a direction parallel to an axis of rotation of the inner rotor, and wherein the resinous member is elastically deformed in the direction parallel to the axis of rotation of the outer rotor and disposed in the casing.