Variable valve system, and engine device and vehicle including the same

Abstract

During a low revolution period, centrifugal force applied to a weight is small and therefore the rotating operation of the weight is restricted. This prevents a lock pin from being fitted to the lock pin fitting hole of a floating cam portion, and the floating cam portion idles around a cam fixing shaft. During a high revolution period, centrifugal force applied to the weight increases, and therefore the weight rotates around the rotation shaft. In this way, the tip end of the lock pin is fitted to the lock pin fitting portion of the floating cam portion. Therefore, during the high revolution period, the floating cam portion is fixed with respect to the rotating direction of the variable valve system by the lock pin.

1 . A variable valve system adapted to drive a valve in an engine, comprising:
 a rotation shaft provided to be rotatable in response to the revolution of said engine;   a first cam member provided to rotate together with said rotation shaft and operating to open/close said valve;   a second cam member provided rotatably with respect to said rotation shaft and operating to open/close said valve;   an engaging member provided to be switchable between a first state in which said second cam member is allowed to rotate with respect to said rotation shaft and a second state in which said second cam member is engaged to said rotation shaft;   an energizing member that generates energizing force that switches said engaging member to said first state; and   a driving member that operates to switch said engaging member to said second state against the energizing force by said energizing member by centrifugal force generated by the rotation of said rotation shaft,   said first cam member operating to open/close said valve when said engaging member is in said first state, said second cam member operating to open/close said valve when said engaging member is in said second state.   
   
   
       2 . The variable valve system according to  claim 1 , wherein said driving member is provided pivotably from a first position to a second position by centrifugal force generated by the rotation of said rotation shaft,
 said engaging member is provided movably in one direction along said rotation shaft as said driving member pivots from said first position to said second position,   said energizing member applies energizing force to said driving member so that said driving member is moved toward said first position, and   said engaging member attains said first state when said driving member is in said first position and said second state when said driving member is in said second position.   
   
   
       3 . The variable valve system according to  claim 1 , wherein said engaging member has an engaging portion,
 said second cam member has an engagement portion to be engaged by said engaging portion of said engaging member,   said engaging portion is disengaged from said engagement portion when said engaging member is in said first state, and   said engaging portion engages said engagement portion when said engaging member is in said second state.   
   
   
       4 . The variable valve system according to  claim 3 , wherein said engaging member includes a rod-shaped member, said engaging portion is an end of said rod-shaped member, and
 said engagement portion of said second cam member is a hole to which the end of said rod-shaped member can be fitted.   
   
   
       5 . The variable valve system according to  claim 4 , wherein said engaging member is a plurality of rod-shaped members, said engagement portion of said second cam member is a plurality of holes to which ends of said plurality of rod-shaped members can be fitted, and
 said plurality of rod-shaped members are provided in asymmetric positions with one another with respect to the center of said rotation shaft.   
   
   
       6 . The variable valve system according to  claim 1 , further comprising a movement stopping member that prevents the movement of said engaging member when said engaging member is in at least one of said first state and said second state. 
   
   
       7 . The variable valve system according to  claim 6 , wherein said engaging member has at least one groove, and
 said movement stopping member has a fitting portion that can be fitted to said groove when said engaging member is in at least one of said first state and said second state.   
   
   
       8 . The variable valve system according to  claim 7 , wherein said groove of said engaging member and said fitting portion of said movement stopping member are formed so that said fitting portion can be withdrawn from said at least one groove at least one of when said engaging member switches from said first state to said second state and when said engaging member switches from said second state to said first state. 
   
   
       9 . The variable valve system according to  claim 1 , further comprising a first transmission member that swings in response to the rotation of said first cam member and moves said valve up and down, and
 a second transmission member that swings said first transmission member in response to the rotation of said second cam member.   
   
   
       10 . The variable valve system according to  claim 1 , wherein said first cam member operates to open said valve with a first lift amount in said first state, and
 said second cam member operates to open said valve with a second lift amount larger than said first lift amount in said second state.   
   
   
       11 . The variable valve system according to  claim 1 , wherein said first cam member operates to open said valve with a first operation angle in said first state, and
 said second cam member operates to open said valve with a second operation angle larger than said first operation angle in said second state.   
   
   
       12 . The variable valve system according to  claim 1 , wherein said valve is an intake valve. 
   
   
       13 . An engine device, comprising:
 an engine having a valve; and   a variable valve system adapted to drive said valve in said engine,   said variable valve system including:   a rotation shaft provided to be rotatable in response to the rotation of said engine;   a first cam member provided to rotate together with said rotation shaft and operating to open/close said valve;   a second cam member provided rotatably with respect to said rotation shaft and operating to open/close said valve;   an engaging member provided to be switchable between a first state in which said second cam member is allowed to rotate with respect to said rotation shaft and a second state in which said second cam member is engaged to said rotation shaft;   an energizing member that generates energizing force that switches said engaging member to said first state; and   a driving member that operates to switch said engaging member to said second state against the energizing force by said energizing member by centrifugal force generated by the rotation of said rotation shaft,   said first cam member operating to open/close said valve when said engaging member is in said first state, said second cam member operating to open/close said valve when said engaging member is in said second state.   
   
   
       14 . A vehicle, comprising:
 an engine device;   a driving wheel; and   a transmission mechanism that transmits motive power generated by said engine device to said driving wheel,   said engine device including:   an engine having a valve; and   a variable valve system adapted to drive said valve in said engine,   said variable valve system including:   a rotation shaft provided to be rotatable in response to the rotation of said engine;   a first cam member provided to rotate together with said rotation shaft and operating to open/close said valve;   a second cam member provided rotatably with respect to said rotation shaft and operating to open/close said valve;   an engaging member provided to be switchable between a first state in which said second cam member is allowed to rotate with respect to said rotation shaft and a second state in which said second cam member is engaged to said rotation shaft;   an energizing member that generates energizing force that switches said engaging member to said first state; and   a driving member that operates to switch said engaging member to said second state against the energizing force by said energizing member by centrifugal force generated by the rotation of said rotation shaft,   said first cam member operating to open/close said valve when said engaging member is in said first state,   said second cam member operating to open/close said valve when said engaging member is in said second state.