Pump

Abstract

The pump ( 10, 110, 210 ) may comprise a casing ( 39, 139, 239 ) and a substantially disk-shaped impeller ( 36, 136, 236 ) that rotates within the casing. A group of depression-shaped grooves may be formed on at least one of the front and reverse surfaces of the impeller and the two casing internal surfaces in opposition to these surfaces. The depression-shaped grooves may extend from the center towards the outer periphery of the impeller. When the impeller rotates, fuel within the clearance between the impeller and the casing is propelled, within the depression-shaped grooves, from the center towards the periphery. In this way, forces are generated in the direction that increases the clearance between the impeller and the casing. It is preferred that the group of depression-shaped grooves 38 b is formed closely spaced near the discharge hole 50 (area B), and elsewhere (area C) is formed more widely spaced. Also, it is preferred that the clearance between the surface on which the depression-shaped grooves 136 c are formed and the surface 138 b in opposition thereto increases from the center of the impeller towards the outer periphery of the impeller.

1 . A pump comprising a casing and a substantially disk-shaped impeller rotating within the casing, wherein 
 a group of concavities is formed on both front and reverse surfaces of the impeller, concavities forming each group are repeated in a circumferential direction of the impeller,    a first groove is formed on a first casing internal surface in opposition to the front surface of the impeller, the first groove extending from an upstream end to a downstream end in an area facing one of the groups of concavities of the impeller,    a second groove is formed on a second casing internal surface in opposition to the reverse surface of the impeller, the second groove extending from an upstream end to a downstream end in an area facing the other of the groups of concavities of the impeller,    an intake hole and a discharge hole are formed in the casing, the intake hole linking the upstream end of one of the first groove and the second groove with the outside of the casing, the discharge hole linking the downstream end of the other of the first groove and the second groove with the outside of the casing, and    a group of depression-shaped grooves is formed in at least the first and second casing internal surfaces, each depression-shaped grooves extends from the center towards the outer periphery while shifting in the direction of rotation of the impeller, and the group of depression-shaped grooves is asymmetrically formed with respect to the axis of rotation of the impeller in accordance with the position of the first and second grooves.    
   
   
       2 . A pump according to  claim 1 , wherein in the area near the discharge hole in the casing internal surface and/or in the area near the intake hole in the casing internal surface, the lift forces generated on the impeller by the group of depression-shaped grooves are greater than in other areas.  
   
   
       3 . A pump according to  claim 1 , wherein the group of depression-shaped grooves is formed only in the area near the discharge hole and/or in the area near the intake hole.  
   
   
       4 . A pump according to  claim 3 , wherein each depression-shaped groove forming the group of depression-shaped grooves extends from the center of the impeller towards the outer periphery of the impeller in a spiral shape.  
   
   
       5 . A pump comprising a casing and a substantially disk-shaped impeller rotating within the casing, wherein 
 a group of concavities is formed on both front and reverse surfaces of the impeller, concavities forming each group are repeated in a circumferential direction of the impeller,    a first groove is formed on a first casing internal surface in opposition to the front surface of the impeller, the first groove extending from an upstream end to a downstream end in an area facing one of the groups of concavities of the impeller,    a second groove is formed on a second casing internal surface in opposition to the reverse surface of the impeller, the second groove extending from an upstream end to a downstream end in an area facing the other of the groups of concavities of the impeller,    an intake hole and a discharge hole are formed in the casing, the intake hole linking the upstream end of one of the first groove and the second groove with the outside of the casing, the discharge hole linking the downstream end of the other of the first groove and the second groove with the outside of the casing,    in at least one surface from among the front and reverse surfaces of the impeller and the first and second casing internal surfaces, depression-shaped grooves are formed so that fluid in the clearance between the impeller and the casing is pressurized and a force is generated in the direction that increases the clearance between the impeller and the casing when the impeller rotates, and    the clearance between the surface on which the depression-shaped grooves are formed and the surface in opposition thereto when the impeller is not inclined with respect to the casing increases from the center of the impeller towards the outer periphery of the impeller.    
   
   
       6 . A pump according to  claim 5 , wherein one surface from among the surface in which the depression-shaped grooves is formed and the surface in opposition thereto is formed as a flat plane, and the other surface is formed in a tapered shape so that the clearance with the impeller increases from the center of the impeller towards the outer periphery of the impeller.  
   
   
       7 . A pump according to  claim 6 , wherein the depression-shaped grooves extend from the center of the impeller towards the outer periphery of the impeller in a spiral shape.  
   
   
       8 . A pump comprising a casing and a substantially disk-shaped impeller rotating within the casing, wherein 
 a group of concavities is formed on both front and reverse surfaces of the impeller, concavities forming each group are repeated in a circumferential direction of the impeller,    a first groove is formed on a first casing internal surface in opposition to the front surface of the impeller, the first groove extending from an upstream end to a downstream end in an area facing one of the groups of concavities of the impeller,    a second groove is formed on a second casing internal surface in opposition to the reverse surface of the impeller, the second groove extending from an upstream end to a downstream end in an area facing the other of the groups of concavities of the impeller,    an intake hole and a discharge hole are formed in the casing, the intake hole linking the upstream end of a pump flow path formed by the groups of concavities, the first groove, and the second groove with the outside of the casing, the discharge hole linking the downstream end of the pump flow path with the outside of the casing,    depression-shaped grooves sealed from the pump flow path are formed on at least one surface from among the intake hole side impeller surface and the intake hole side casing internal surface, and depression-shaped grooves sealed from the pump flow path are formed in neither the discharge hole side impeller surface nor the discharge hole side casing internal surface.    
   
   
       9 . A pump according to  claim 8 , wherein a projecting portion is formed in the discharge hole side casing internal surface as a loop in the circumferential direction of the impeller.  
   
   
       10 . A pump according to  claim 9 , wherein the depression-shaped grooves extend from the center of the impeller towards the outer periphery of the impeller in a spiral shape.  
   
   
       11 . A pump according to  claim 8 , further comprising a motor chamber provided on the outside of the casing, and a motor housed within the motor chamber, wherein the motor includes a shaft that rotates, the discharge hole links the pump flow path and the motor chamber, a through hole that is penetrated by the motor shaft are formed in the casing, and one end of the motor shaft is fitted to the impeller.  
   
   
       12 . A pump comprising a casing and a substantially disk-shaped impeller rotating within the casing, wherein 
 a group of concavities is formed on both front and reverse surfaces of the impeller, concavities forming each group are repeated in a circumferential direction of the impeller,    a first groove is formed on a first casing internal surface in opposition to the front surface of the impeller, the first groove extending from an upstream end to a downstream end in an area facing one of the groups of concavities of the impeller,    a second groove is formed on a second casing internal surface in opposition to the reverse surface of the impeller, the second groove extending from an upstream end to a downstream end in an area facing the other of the groups of concavities of the impeller,    an intake hole and a discharge hole are formed in the casing, the intake hole linking the upstream end of a pump flow path formed by the groups of concavities, the first groove, and the second groove with the outside of the casing, the discharge hole linking the downstream end of the pump flow path with the outside of the casing,    intake hole side depression-shaped grooves are formed on at least one surface from among the intake hole side impeller surface and the intake hole side casing internal surface so that when the impeller rotates fluid is pressurized and a lift force is generated that acts in the direction to increase the clearance between the intake hole side impeller surface and the intake hole side casing internal surface,    discharge hole side depression-shaped grooves are formed on at least one surface from among the discharge hole side impeller surface and the discharge hole side casing internal surface so that when the impeller rotates fluid is pressurized and a lift force is generated that acts in the direction to increase the clearance between the discharge hole side impeller surface and the discharge hole side casing internal surface, and    the number and/or shape of the discharge hole side depression-shaped grooves are determined so that the lift force generated is smaller than the lift force generated by the intake hole side depression-shaped grooves, in accordance with the number and/or shape of the intake hole side depression-shaped grooves.