Cam follower device

Abstract

A cam follower device includes a pair of plate-shaped rocker arms 17 parallel mutually, a support shaft 7 a fixed in support holes 8 a , 8 a at one end portions of the rocker arms 17 at both end portions and a tappet roller 9 supported rotatably around a circumference of an intermediate portion of the support shaft 7 a . When the cam follower device is built in a valve train, rotary motion of a cam 2 provided on a camshaft is transmitted to valve elements 12 constituting two inlet (or exhaust) valves by the tappet roller 9 and the pair of rocker arms 17 so as to reciprocate the two valve elements 12 axially. By this configuration, the number of components in a valve train of an engine, in which a number of at least one of inlet and exhaust valves per cylinder is two or more, can be reduced.

1 . A cam follower device that is built in a valve train of an engine in which a number of at least one of inlet valves and exhaust valves which are to be provided per cylinder is two or more, comprising:
 a pair of rocker arms which are disposed parallel to each other with a predetermined interval provided therebetween and have a pair of support holes which are concentric with each other at one end portions or intermediate portions thereof in positions which are aligned with each other;   a support shaft which is fixed to both the rocker arms so as to be extended between the rocker arms by fitting both end portions in the support holes, respectively;   a tappet roller which is supported rotatably around a periphery of an intermediate portion of the support shaft, an outer circumferential surface of the tappet roller being capable of abutting with an outer circumferential surface of a cam which is fixed on a camshaft when the cam follower device is built in the valve train; and   a pair of pressing portions which are provided directly or via a separate member at the other end portions of both the rocker arms, the pair of pressing portions being capable of striking individually proximal end faces of two inlet valves or two exhaust valves when the cam follower device is built in the valve train.   
   
   
       2 . The cam follower device as set forth in  claim 1 , wherein
 the pair of rocker arms is formed separately.   
   
   
       3 . The cam follower device as set forth in  claim 2 , wherein
 the pair of support holes are formed at the one end portions of the pair of rocker arms, and   a pair of through holes, into which a rocker arm shaft provided in parallel with the camshaft is capable of being inserted when the cam follower device is built in the valve train, are formed at the intermediate portions of the rocker arms in positions which are aligned with each other, so as to enable a swinging displacement of both the rocker arms.   
   
   
       4 . The cam follower device as set forth in  claim 3 , wherein
 an interval between inner surfaces of both the rocker arms which confront each other are made relatively narrow at the one end portions and relatively wide at the other end portions of both the rocker arms by making thickness of both the rocker arms relatively large at the one end portions and relatively small at the other end portions of both the rocker arms.   
   
   
       5 . The cam follower device as set forth in  claim 3 , wherein
 an interval between inner surfaces of both the rocker arms which confront each other are made relatively narrow at the one end portions and relatively wide at the other end portions of both the rocker arms by providing non-parallel plate portions which are not parallel to the intermediate portions of both the rocker arms at portions between the one end portions and the intermediate portions or between the intermediate portions and the other end portions of both the rocker arms.   
   
   
       6 . The cam follower device as set forth in  claim 3 , wherein
 both end portions of a cylindrical sleeve are inwardly fitted and fixed, respectively, in the pair of through holes and   the rocker arm shaft is inserted into an inside of the sleeve.   
   
   
       7 . The cam follower device as set forth in  claim 2 , wherein
 the pair of support holes are formed at the intermediate portions of the pair of rocker arms, and   the one end portions of both the rocker arms have a pair of receiving portions which are provided thereon directly or via separate members and with which distal end faces of a pair of plungers is capable of being brought into abutment when the cam follower device is built in the valve train, so as to enable a swinging displacement of both the rocker arms about abutment portions between the receiving portions and the distal end faces of the pair of plungers as fulcrums.   
   
   
       8 . The cam follower device as set forth in  claim 7 , wherein
 an interval between inner surfaces of both the rocker arms which confront each other are made relatively narrow at the one end portions and relatively wide at the other end portions of both the rocker arms by making thickness of both the rocker arms relatively large at the one end portions and relatively small at the other end portions of both the rocker arms.   
   
   
       9 . The cam follower device as set forth in  claim 7 , wherein
 an interval between inner surfaces of both the rocker arms which confront each other are made relatively narrow at the one end portions and relatively wide at the other end portions of both the rocker arms by providing non-parallel plate portions which are not parallel to the intermediate portions of both the rocker arms at portions between the one end portions and the intermediate portions or between the intermediate portions and the other end portions of both the rocker arms.   
   
   
       10 . The cam follower device as set forth in  claim 1 , wherein
 an axial displacement amount allowed to the tappet roller is controlled to a desired magnitude by disposing spacers which are fitted on the support shaft, respectively, between inner surfaces of both the rocker arms and both axial end faces of the tappet roller.   
   
   
       11 . The cam follower device as set forth in  claim 1 , wherein
 thickness of portions of both the rocker arms which need to have a higher strength than that of peripheral areas thereof are larger than thickness of the peripheral areas.   
   
   
       12 . The cam follower device as set forth in  claim 2 , wherein
 the pair of rocker arms is each formed by applying stamping process to a single sheet metal.   
   
   
       13 . The cam follower device as set forth in  claim 1 , wherein
 the pair of rocker arms is connected together by a connecting portion provided in at least one location so as to prohibit a relative displacement.   
   
   
       14 . The cam follower device as set forth in  claim 13 , wherein
 the pair of support holes are formed at the one end portions of the pair of rocker arms, and   a pair of through holes into which a rocker arm shaft provided in parallel with the camshaft is capable of being inserted when the cam follower device is built in the valve train, are formed at the intermediate portions of the rocker arms in positions which are aligned with each other, so as to enable a swinging displacement of both the rocker arms.   
   
   
       15 . The cam follower device as set forth in  claim 13 , wherein
 the pair of rocker arms which are connected together by the connecting portion provided in at least the one location so as to prohibit a relative displacement are made by applying stamping process and bending process to a single sheet metal.