INTAKE AND EXHAUST VALVE FOR VEHICLE
An intake/exhaust valve for a vehicle to prevent the valve from fixation (valve absorption) may include a first valve stem body which is extruded from a valve head, has a first diameter and is a portion where a relative motion of a valve stem occurs; and a second valve stem body which is formed above the first valve stem body and has a second diameter. The second diameter is less than the first diameter. The relative clearance between the first valve stem body and a valve guide is predetermined for stable guiding of a valve closing, and the relative clearance between the second valve stem body and the valve guide is predetermined for preventing carbon fixation.
1 . An intake/exhaust valve for a vehicle comprising:
a valve head;
a first valve stem body which is extruded from the valve head, has a first diameter and is a portion where a relative motion of a valve stem occurs; and
a second valve stem body which is formed above the first valve stem body and has a second diameter;
wherein the second diameter is less than the first diameter.
2 . The intake/exhaust valve of claim 1 , wherein a portion is formed between the first valve stem body and the second valve stem body with a varied diameter.
3 . The intake/exhaust valve of claim 2 , wherein the diameter of the portion between the first valve stem body and the second valve stem body changes linearly.
4 . The intake/exhaust valve of claim 1 , wherein a length of the first valve stem body is a predetermined length for preventing the valve from interference.
5 . The intake/exhaust valve of claim 4 , wherein the predetermined length is determined so that when the valve is positioned at a lowest potion, the lowest position of the valve is not corresponding to a piston top dead center position.
6 . The intake/exhaust valve of claim 1 , wherein the second diameter is approximately 20 μm smaller than the first diameter.
7 . An intake/exhaust valve for a vehicle comprising:
a valve head;
a first valve stem body which is extruded from a valve head, has a first diameter and is a portion where a relative motion of a valve stem occurs; and
a second valve stem body which is formed above the first valve stem body and has a second diameter;
wherein a relative clearance between the first valve stem body and a valve guide is predetermined for stable guiding of a valve closing, and
a relative clearance between the second valve stem body and the valve guide is predetermined for preventing a valve fixation.
8 . The intake/exhaust valve of claim 7 , wherein a length of the first valve stem body is a predetermined length for stable guiding of the valve closing.
9 . The intake/exhaust valve of claim 7 , wherein the relative clearance between the first valve stem body and the valve guide is approximately 0.020-0.040 mm, and the relative clearance between the second valve stem body and the valve guide is approximately 0.040-0.060 mm.