Oil pump for internal combustion engine

Abstract

A first fitting portion is coupled to a protruding end of the crankshaft to be rotatable about a crankshaft rotational axis. An intermediate member includes a first hole wall slidably supporting the first fitting portion in a first direction orthogonal to the crankshaft rotational axis so that the intermediate member rotates together with the crankshaft. An inner rotor includes a second hole wall slidably supporting the second fitting portion in a second direction orthogonal to the first direction and the crankshaft rotational axis so that the inner rotor rotates together with the intermediate member. One of the first direction and the second direction is in parallel with a line segment joining the crankshaft rotational axis and an axis of a crankpin of the internal combustion engine which is closest to the protruding end of the crankshaft.

What is claimed is: 
     
         1 . An oil pump for an internal combustion engine, comprising:
 a crankshaft that is supported on an internal combustion engine body so as to be rotatable about a predetermined crank axis;   an inner rotor that is connected to one end of the crankshaft via an Oldham's coupling; and   an outer rotor that is rotatably accommodated in a pump housing coupled to the internal combustion engine body, and meshes at an inner circumferential part thereof with an outer circumferential part of the inner rotor, wherein   the Oldham's coupling has:
 a first fitting portion that is provided at the one end of the crankshaft; 
 an intermediate member that includes
 a first fitting hole accommodating the first fitting portion so that the first fitting portion is slidable in a first direction orthogonal to an axis of the crankshaft and rotates together with the first fitting hole, and 
 a second fitting portion; and 
 
 a second fitting hole that accommodates the second fitting portion so that the second fitting portion is slidable in a second direction orthogonal to the first direction and rotates together with the second fitting hole, and 
   any one of the first direction and the second direction extends parallel with a line segment that joins an axis of a crankpin closest to the one end of the crankshaft and the axis of the crankshaft.   
     
     
         2 . The oil pump according to  claim 1 , wherein
 the first fitting portion, the first fitting hole, the second fitting portion, and the second fitting hole are arranged on one plane orthogonal to the axis of the crankshaft.   
     
     
         3 . The oil pump according to  claim 1 , wherein
 the first fitting portion has:
 a pair of first side faces that extend parallel with the first direction with the axis of the crankshaft interposed therebetween; and 
 a pair of arcuate first side end faces that join opposed end parts of the pair of first side faces, 
   the first fitting hole has:
 a pair of planar first hole wall faces that are in sliding contact with the paired first side faces respectively; and 
 a pair of arcuate first hole wall end faces that join opposed end parts of the pair of first hole wall faces, and 
   each first hole wall end face has a curvature smaller than each first side end face.   
     
     
         4 . The oil pump according to  claim 1 , wherein
 the second fitting portion has:
 a pair of second side faces that extend parallel with the second direction with the axis of the crankshaft interposed therebetween; and 
 a pair of arcuate second side end faces that join opposed end parts of the pair of second side faces, 
   the second fitting hole has:
 a pair of planar second hole wall faces that are in sliding contact with the paired second side faces respectively; and 
 a pair of arcuate second hole wall end faces that join opposed end parts of the pair of second hole wall faces, and 
   each second hole wall end face has a curvature smaller than each second side end face.   
     
     
         5 . The oil pump according to  claim 1 , wherein
 the one end of the crankshaft penetrates the pump housing,   the pump housing has, on a distal side thereof in a direction of the axis of the crankshaft, a distal-side wall portion that is in sliding contact with an end face of the inner rotor on the distal side and has, on a proximal side thereof in the direction of the axis of the crankshaft, a proximal-side wall portion that is in sliding contact with end faces of the inter rotor and the intermediate member on the proximal side,   the crankshaft is provided with a restriction wall that is in sliding contact with an end face of the intermediate member on the distal side,   an oil seal designed to seal a space between the distal-side wall portion and any one of the crankshaft and a member coupled integrally to the crankshaft is provided,   the first fitting hole penetrates the intermediate member in the direction of the axis of the crankshaft, and   the second fitting hole penetrates the inner rotor in the direction of the axis of the crankshaft.   
     
     
         6 . The oil pump according to  claim 1 , further comprising
 a crank pulley that includes:
 a circular pulley body portion; and 
 a pulley cylindrical portion which is provided at a center of the pulley body portion and in which the one end of the crankshaft is inserted unrotatably, wherein 
   the first fitting portion is formed in an outer circumferential face of the pulley cylindrical portion.   
     
     
         7 . The oil pump according to  claim 1 , wherein
 the internal combustion engine body has:
 a cylinder block; and 
 a chain cover that is coupled to an end face of the cylinder block on one end side thereof in the direction of the axis of the crankshaft, and forms a space with the cylinder block therebetween, and 
   the pump housing is provided in the chain cover.   
     
     
         8 . The oil pump according to  claim 1 , wherein
 the inner rotor has a cylindrical boss portion having an axis of the inner rotor as a center thereof, and   the pump housing has a circular fitting hole in which the boss portion is fitted rotatably.   
     
     
         9 . An oil pump for an internal combustion engine, comprising:
 a pump housing coupled to an engine body of the internal combustion engine;   a crankshaft supported on the engine body to be rotatable about a crankshaft rotational axis, the crankshaft having a protruding end protruding from the engine body;   a first fitting portion coupled to the protruding end of the crankshaft;   an intermediate member slidably coupled to the first fitting portion, the intermediate member comprising:
 a first hole wall surrounding the crankshaft rotational axis and defining a first fitting hole in which the first fitting portion is provided, the first hole wall slidably supporting the first fitting portion in a first direction orthogonal to the crankshaft rotational axis so that the intermediate member rotates together with the crankshaft; and 
 a second fitting portion provided to be opposite to and around the first hole wall; 
   an inner rotor slidably coupled to the intermediate member to be rotatable about an inner rotor rotational axis parallel to the crankshaft rotational axis, the inner rotor comprising:
 a second hole wall surrounding the inner rotor rotational axis and defining a second fitting hole in which the second fitting portion is provided, the second hole wall slidably supporting the second fitting portion in a second direction orthogonal to the first direction and the crankshaft rotational axis so that the inner rotor rotates together with the intermediate member, one of the first direction and the second direction being in parallel with a line segment joining the crankshaft rotational axis and an axis of a crankpin of the internal combustion engine which is closest to the protruding end of the crankshaft; and 
 an inner rotor outer circumferential part provided to be opposite to and around the second hole wall; and 
   an outer rotor accommodated in the pump housing to be rotatable about an outer rotor rotational axis parallel to the crankshaft rotational axis and comprising an outer rotor inner circumferential part surrounding the outer rotor rotational axis to mesh with the inner rotor outer circumferential part.   
     
     
         10 . The oil pump according to  claim 9 , wherein
 the first fitting portion, the first fitting hole, the second fitting portion, and the second fitting hole are arranged on one plane orthogonal to the crankshaft rotational axis.   
     
     
         11 . The oil pump according to  claim 9 , wherein
 the first fitting portion has:
 a pair of first side faces that extend parallel with the first direction with the axis of the crankshaft interposed therebetween; and 
 a pair of arcuate first side end faces that join opposed end parts of the pair of first side faces, 
   the first hole wall has:
 a pair of planar first hole wall faces that are in sliding contact with the paired first side faces respectively; and 
 a pair of arcuate first hole wall end faces that join opposed end parts of the pair of first hole wall faces, and 
   each first hole wall end face has a curvature smaller than each first side end face.   
     
     
         12 . The oil pump according to  claim 9 , wherein
 the second fitting portion has:
 a pair of second side faces that extend parallel with the second direction with the axis of the crankshaft interposed therebetween; and 
 a pair of arcuate second side end faces that join opposed end parts of the pair of second side faces, 
   the second fitting wall has:
 a pair of planar second hole wall faces that are in sliding contact with the paired second side faces respectively; and 
 a pair of arcuate second hole wall end faces that join opposed end parts of the pair of second hole wall faces, and 
   each second hole wall end face has a curvature smaller than each second side end face.   
     
     
         13 . The oil pump according to  claim 9 , wherein
 the protruding end of the crankshaft penetrates the pump housing,   the pump housing has, on a distal side thereof in a direction of the crankshaft rotational axis, a distal-side wall portion that is in sliding contact with an end face of the inner rotor on the distal side and has, on a proximal side thereof in the direction of the crankshaft rotational axis, a proximal-side wall portion that is in sliding contact with end faces of the inter rotor and the intermediate member on the proximal side,   the crankshaft is provided with a restriction wall that is in sliding contact with an end face of the intermediate member on the distal side,   an oil seal designed to seal a space between the distal-side wall portion and any one of the crankshaft and a member coupled integrally to the crankshaft is provided,   the first fitting hole penetrates the intermediate member in the direction of the crankshaft rotational axis, and   the second fitting hole penetrates the inner rotor in the direction of the crankshaft rotational axis.   
     
     
         14 . The oil pump according to  claim 9 , further comprising
 a crank pulley that includes:
 a circular pulley body portion; and 
 a pulley cylindrical portion which is provided at a center of the pulley body portion and in which the protruding end of the crankshaft is inserted unrotatably, wherein 
   the first fitting portion is formed in an outer circumferential face of the pulley cylindrical portion.   
     
     
         15 . The oil pump according to  claim 9 , wherein
 the engine body has:
 a cylinder block; and 
 a chain cover that is coupled to an end face of the cylinder block on one end side thereof in the direction of the crankshaft rotational axis, and forms a space with the cylinder block therebetween, and 
   the pump housing is provided in the chain cover.   
     
     
         16 . The oil pump according to  claim 9 , wherein
 the inner rotor has a cylindrical boss portion a center of which is the inner rotor rotational axis, and   the pump housing has a circular fitting hole in which the boss portion is fitted rotatably.