Valve timing change device

Abstract

A valve timing change device changes a relative rotation phase between a camshaft and a housing rotor which interlocks with rotation of a crankshaft to change open/close timing of an exhaust valve driven by the camshaft to an advancing side or a retarding side. The valve timing change device includes a rotation member which is driven to rotate by being exerted a rotation driving force; an external gear which is interlocked with the rotation member; a first internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the housing rotor; and a second internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the camshaft, and has a number of teeth smaller than the number of teeth of the first internal gear.

What is claimed is: 
     
         1 . A valve timing change device, which changes a relative rotation phase between a camshaft and a housing rotor which interlocking with a rotation of a crankshaft to change an open/close timing of an exhaust valve driven by the camshaft to an advancing side or a retarding side, the valve timing change device comprising:
 a rotation member which is driven to rotate by being exerted a rotation driving force;   an external gear which is interlocked with the rotation member;   a first internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the housing rotor; and   a second internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the camshaft, the second internal gear having a number of teeth smaller than a number of teeth of the first internal gear.   
     
     
         2 . The valve timing change device according to  claim 1 , wherein
 the external gear is formed to be elastically deformable to be directly meshed with the first internal gear and the second internal gear; and   the rotation member comprises a cam portion which exerts, to the external gear, a cam action generating elliptic deformation for meshing with the external gear.   
     
     
         3 . The valve timing change device according to  claim 2 , wherein
 the cam portion of the rotation member is fitted to an inner side of the external gear via a bearing that is elliptically deformable.   
     
     
         4 . The valve timing change device according to  claim 1 , wherein
 the external gear is formed into an annular shape to be directly meshed with the first internal gear and the second internal gear; and   the rotation member comprises an eccentric portion which exerts an eccentricity action to mesh the external gear with the first internal gear and the second internal gear while making the external gear eccentric.   
     
     
         5 . The valve timing change device according to  claim 4 , wherein
 the eccentric portion of the rotation member is fitted to an inner side of the external gear via a bearing.   
     
     
         6 . The valve timing change device according to  claim 1 , wherein
 the number of teeth of the second internal gear is the same as the number of teeth of the external gear.   
     
     
         7 . The valve timing change device according to  claim 1 , wherein
 the external gear is arranged to be indirectly meshed with the first internal gear and the second internal gear via a planetary gear; and   the rotation member is integrally formed with the external gear as a portion of the external gear.   
     
     
         8 . The valve timing change device according to  claim 1 , wherein
 the housing rotor is rotatably supported around an axis line of the camshaft via the second internal gear.   
     
     
         9 . The valve timing change device according to  claim 1 , comprising
 a spacer member which is joined to the camshaft, wherein   the second internal gear is fixed to the camshaft via the spacer member, and   the spacer member is formed in a manner that a relative rotation range is regulated with respect to the housing rotor.   
     
     
         10 . The valve timing change device according to  claim 1 , wherein the housing rotor comprises:
 a first housing which is cylindrical and has a sprocket on an outer periphery of the first housing, and   a second housing which is disc-shaped, bound to the first housing and has an opening portion for exposing an end portion of the rotation member.   
     
     
         11 . The valve timing change device according to  claim 1 , comprising
 an electric motor which exerts the rotation driving force on the rotation member.   
     
     
         12 . The valve timing change device according to  claim 11 , wherein
 the electric motor comprises a housing, and a rotation shaft which is rotatably supported by the housing and is coupled to the rotation member, and   the housing is fixed to a cover member of an engine.