the valve guide is a guide means automotive engine valve, the valve is a valve of the catheter from the guide, the valve stem and the heat transmitted to the cylinder head through the valve guide.
1. Basic information catheter valve
is a function of the valve guide movement of the valve guide, the valve reciprocating linear motion to ensure that the valve and valve seat fit properly, and the valve the heat is transferred to the rod of the cylinder head.
The operating temperature of the valve guide is also high, about 200 ℃. When the movement of the valve stem in the conduit, relying valve mechanism for lubricating oil is splashed, it is easy to wear. Therefore, a separate part made of spheroidal graphite cast iron, or powder metallurgical plurality since the sliding material having properties, with a certain interference pressed into the valve guide bore in the cylinder head, to prevent loss. Some engine valve guide in order to prevent loosening of the retaining ring using the catheter with the fixed positioning. Extending into the lower valve guide
into the exhaust passage, in order to prevent resistance to air flow, the outer end projects into a conical end. 0.05 ~ 0.12mm clearance between the valve guide and valve stem, the valve stem can move freely within the catheter.
2. The valve guide valve guide structure
of the valve guide which reciprocates within the valve play in the role of a support guide, valve and valve seat can ensure proper fit, and from heat conduction.
and the valve guide insert with integral into two. Integral valve guide in the cylinder head directly machined valve stem bore. Insert-in valve guide in the cylinder head bore of the conduit is pressed into an interference cylindrical pipe, interference of 0.015 ~ 0.065mm.
Some of the outer cylindrical valve guides machined with an annular groove, the snap ring insert positioned, the lower end further limiting the depth of the airways and prevent loosening. Generally 0.05 ~ 0.12mm with the gap left between the
the valve stem and valve guide. The valve train parts are lubricated by oil splash out between them.
When the valve stem and valve guide gap is too small, it is easy to cause seizure of the valve stem, seal failure, the valve will cause burning of the power, economy, lowered emissions and the like.
If the valve stem and valve guide clearance is too large, it will cause irregularities following:
① valve seating is not stable, decreased sealability, and accelerated wear, resulting in valve burning, power, economy, emission such as a decrease.
② intake leak, gasoline engine becomes lean mixture.
③ excessive oil flow downward through the gap into the combustion chamber or airway (particularly in the intake process), resulting in increased oil consumption, blue smoke, accelerated coke formation.
④ exhaust stroke, the exhaust gas into the crankcase through an exhaust valve stem and valve guide clearance.
⑤ When the exhaust port pressure is lower than the pressure in the crankcase, the oil through an exhaust valve stem and vent valve guide clearanceLeak to the exhaust port.
The reason for starting blue smoke exhaust duct often gap is too large, the oil through the exhaust conduit shutdown percolated down through the gap into the combustion chamber door and the adhesion of the exhaust manifold, it is burned at startup. This phenomenon will increase as the temperature of the engine to reduce or disappear.
Function valve seal is to prevent too much oil into the combustion chamber or intake, exhaust passage through a gap flow valve guide and valve stem. It is a rubber ring, mounted on the upper end of the valve guide. If the valve seal is damaged, there will be too much oil through the valve and the valve guide clearance flow down the combustion chamber or human airways, leading to increased oil consumption, along with the exhaust gas blue smoke, the acceleration valve and combustion chamber coke Formation.
3. The valve guide catheter exchange valve
Valve replacement catheter exchange method is divided into two kinds of a flange and a valve guide without replacing the valve guide flange. When
A flange catheter valve
in the whole of the cylinder head box thermostat heated to 100 ~ 150 ℃, branched and taken out from the cylinder head, a valve with a valve guide catheter removal tools will hit the side towards the camshaft ; then the new O-ring Lubricate new valve mounted on the conduit, then the new valve guide into the valve guide from the camshaft side with a detachable tool; after cooling the cylinder head, the valve the bore in the conduit drops more cutting oil, by trimming of the valve guide reamer valve guide, the valve stem to obtain a suitable clearance with the valve guide; Finally, gasoline or kerosene the cylinder head cleaning installation used to clean thoroughly. More
In other non-flanged valve guide
before working cylinder valve guide, with a vernier caliperMeasure the height of the exposed portion, and make records. When the thermostat on the cylinder head box was heated to 100-150 deg.] C, remove the support from the cylinder head and, with the valve guide catheter removal tools will hit the valve side towards the camshaft; then the new tool is detachably valve guide valve driving the camshaft from the side of the conduit, the valve and measuring the height of the edge portion of the catheter is exposed, while a little bit into the new valve guide until it meets the requirements; after cooling the cylinder head, drops into the hole in the valve guide these cutting oil,) J of the valve with the valve guide catheter hinge trimmed to obtain a suitable valve stem and valve guide with the gap; Finally, gasoline or kerosene the cylinder head cleaning installation used to clean thoroughly.