Valve seats are one of the components of a diesel generator set. They are round surfaces machined into the cylinder block or cylinder head, with the valve cone sealing or seating on the valve seats, which provide a sealing surface for the intake and exhaust valves to prevent gas leakage. These valve seats also help to dissipate the heat that accumulates on the valves.
Types of valve seats
There are two types of valve seats: one-piece and inserted.
Similar to valve guides, one-piece valve seats are cast directly as part of the cylinder head.
They are cast directly as part of the cylinder head; inserted valve seats use a metal ring as a valve seat that is pressed into the cylinder body and needs to be ground to the correct angle. Engines with aluminum cylinder heads usually use inserted valve seats. Inserted valve seats can be made of cast iron, hardened cast iron, high chromium steel and tungsten-chromium-cobalt alloy (a very hard steel).
To ensure proper operation of the diesel generator set, the valve seats are ground to a specified angle, such as 30° or 45°, etc. There is usually an interference angle when grinding the valves. By grinding the angle of the valve cone to about 1° smaller than the angle of the valve seat, the interference angle can be obtained.
For example, the valve is ground to 44° and the valve seat is ground to 45°. The presence of the interference angle allows the valve to cut through deposits on the valve seat when it is seated, and it also produces a better mechanical seal. As the engine runs and the valve seats wear, the interference angle will gradually disappear. The result is a good linear contact that facilitates the transfer of excess heat from the valve and also facilitates faster valve seating into the cylinder head.
Replace valve seat ring
Valve seat ring is the main role is to seal the valve and withstand high-speed impact, for generator sets, diesel generator set valve seat ring loose, fracture, burn or wear depression too deep, are required to replace the new seat ring, replacement steps are as follows.
1, take off the old valve seat ring.
With flat pliers will have been loose and broken valve seat chisel, and then clamp out, for the inlay is very strong valve seat, you can move a section of steel welded to the valve seat ring on the inner mouth, from the conduit hole to extend a length of the old valve rod, the valve seat ring out.
2, clean up the surface of the seat hole stop. Clear the metal flakes, oxide and other foreign matter inside the valve seat hole stop, check whether the geometry of the stop is regular. If in accordance with the original seat ring when the seat ring around the force is too large, room seat ring hole closure is too large, available scraper will be scraped around the seat hole a little in order to press into the new seat, be sure to ensure that the seat hole and the seat ring with the surface integrity, smooth, no foreign matter.
3、Cold shrink valve seat. Put the new valve seat into the liquid oxygen cooling 10min, use the pointed pliers to take out into the seat hole stop right, insert the special tool pressed into, should actually press the seat to the bottom, and the seat hole fit closely.
4, with a curved edge of the flat chisel will be fixed along the circumference of the seat hole, so that the closure, squeeze the seat ring. Reaming valve seat ring.
