Valve Assembly

Abstract

There is provided a valve assembly including: a valve attached to a cylinder head in a movable manner along its axial line direction so as to selectively fluidly connect or close between a combustion chamber and a gas line; a plate-like holding member provided at the valve in a relatively immovable manner along the axial line direction; and a coil spring externally inserted around the valve in a state where its proximal end is directly or indirectly engaged to an external surface of the cylinder head, the coil spring being configured so that its distal end has a diameter smaller than that of the proximal end, wherein the holding member has an engaging surface facing one side along the axial line direction to hold the distal end of the coil spring.

1 . A valve assembly comprising:
 a valve attached to a cylinder head in a movable manner along its axial line direction so as to selectively fluidly connect or close between a combustion chamber and a gas line;   a plate-like holding member provided at the valve in a relatively immovable manner along the axial line direction; and   a coil spring externally inserted around the valve in a state where its proximal end is directly or indirectly engaged to an external surface of the cylinder head, the coil spring being configured so that its distal end has a diameter smaller than that of the proximal end, wherein   the holding member has an engaging surface facing one side along the axial line direction to hold the distal end of the coil spring.   
   
   
       2 . A valve assembly according to  claim 1 , wherein the coil spring has a concave portion, into which the holding member is engaged, at an end surface of the distal end. 
   
   
       3 . A valve assembly according to  claim 1 , wherein the holding member includes a center hole having a diameter larger than an outer diameter of a concave groove formed at a shaft portion of the valve and smaller than an outer diameter of the shaft portion, and a slit opening the center hole to outside. 
   
   
       4 . A valve assembly comprising:
 a valve attached to a cylinder head in a movable manner along its axial line direction so as to selectively fluidly connect or close between a combustion chamber and a gas line;   a plate-like holding member provided at the valve in a relatively immovable manner along the axial line direction, the holding member having an engaging surface facing one side along the axial line direction;   a plate-like retainer externally inserted around the valve in a relatively movable manner along the axial line direction in a state where its inner peripheral surface slidably contacts an outer peripheral surface of the valve, the retainer having a contacting surface that faces the other side along the axial line direction and contacts the engaging surface of the holding member so that an end of a movable area of the retainer towards the other side along the axial line direction is defined; and   a coil spring externally inserted around the valve in a state where its proximal end is directly or indirectly engaged to an external surface of the cylinder head, the coil spring being configured so that its distal end has a diameter smaller than that of the proximal end, wherein   the retainer has a supporting surface facing the one side along the axial line direction to hold the distal end of the coil spring.   
   
   
       5 . A valve assembly according to  claim 4 , wherein the retainer has an outer diameter smaller than an inner diameter of the proximal end of the coil spring. 
   
   
       6 . A valve assembly according to  claim 1 , wherein
 the valve is inserted into an axial line hole of a valve guide in a movable manner along the axial line direction, the valve guide being fixed to the cylinder head; and   the coil spring has an enlarged diameter portion extending from the proximal end towards the other side along the axial line direction so as to surround the valve guide, and a tapered portion that has a diameter becoming smaller as extending from the enlarged diameter portion towards the other side along the axial line direction and terminates at the distal end.   
   
   
       7 . A valve assembly according to  claim 6 , wherein the inner diameter of the distal end of the coil spring is smaller than the outer diameter of the valve guide. 
   
   
       8 . A valve assembly according to  claim 1 , wherein
 the valve comprises a stem member that includes a shaft portion and a flare portion extending towards the one side along the axial line direction from the shaft portion, the stem member having a hollow portion of which the flare portion is an open end, and a lid member fixed to the flare portion of the stem member by caulking;   the flare portion includes an enlarged diameter portion having a diameter becoming larger as extending towards the one side along the axial line direction and a reduced diameter portion extending from the enlarged diameter portion towards the one side along the axial line direction with a flexion point in between, the reduced diameter portion intersecting the enlarged diameter portion in a longitudinal cross sectional view; and   the lid member is sandwiched by the enlarged diameter portion and the reduced diameter portion.