Planetary gear device for vehicle, having clutch drum provided with retainer ring

Abstract

A vehicle planetary gear device including a sun gear, a carrier, a ring gear, a clutch drum, clutch plates axially slidably fitted in the drum, a backing plate fixedly disposed in the drum on one side of a series of clutch plates, and a piston axially movable fitted in the drum and disposed on the other side of the series of clutch plates, and wherein the ring gear is fixedly fitted in the drum with its engaging teeth held in engagement with engaging grooves of the drum, and only two retainer rings are fixed on the drum and disposed on opposite sides of the ring gear and in contact with the teeth of the ring gear, or at least one retainer ring is fixed on the drum and disposed in contact with the teeth of one-piece member consisting of the ring gear and the backing plate, whereby axial movements of the backing plate and the ring gear relative to the drum are prevented by the two retainer rings or the at least one retainer ring.

1 . A planetary gear device for an automotive vehicle, comprising (a) three rotary elements consisting of a sun gear, a carrier and a ring gear, (b) a clutch drum having a plurality of engaging grooves formed in its inner circumferential surface and parallel to its axial direction, (c) a plurality of friction members fitted in said clutch drum such that said friction members are rotatable with said clutch drum and axially movable relative to said clutch drum, each of said friction members having a plurality of engaging teeth formed on its outer circumferential surface and held in engagement with the respective engaging grooves of said clutch drum, (d) an abutting member having a plurality of engaging teeth formed on its outer circumferential surface, fixed in said clutch drum at said engaging teeth thereof and disposed on one side of a series of said friction members such that said abutting member is rotatable with said clutch drum and abuttable on a nearest one of said friction members, and (e) a piston slidably fitted in said clutch drum and disposed on the other side of said series of the friction members such that said piston is axially movable relative to said clutch drum, to press said friction members toward said abutting member, and wherein said ring gear has a plurality of engaging teeth formed on its outer circumferential surface, fixedly fitted in said clutch drum at said engaging teeth thereof such that said ring gear is rotatable with said clutch drum, said planetary gear device further comprising: 
 a first retainer ring and a second retainer ring which are fixed on said clutch drum, to prevent axial movements of said abutting member and said ring gear relative to said clutch drum, said first retainer ring being disposed between and in contact with said engaging teeth of said abutting member and said engaging teeth of said ring gear, while said second retainer ring being disposed on one side of a radially outer portion of said ring gear having its engaging teeth, which one side is remote from said piston, said second retainer ring being held in contact with said engaging teeth of said ring gear.    
   
   
       2 . A planetary gear device according to  claim 1 , wherein said first and second retainer ring are fixed on said inner circumferential surface of said clutch drum in which said plurality of engaging grooves are formed.  
   
   
       3 . A planetary gear device according to  claim 1 , wherein said radially outer portion of said ring gear is an outwardly extending flange formed at one axial end of said ring gear which is adjacent to said abutting member.