As an important part of the valve train of diesel generator set, valve group includes many parts, such as valve, valve seat, valve spring, valve guide, spring seat and so on.

气门座是与气门密封锥面相配合的支承面它与气门共同保证密封性能，同时它还要把气门头部的热量传递出去。

The valve seat is a bearing surface matched with the valve sealing cone. It ensures the sealing performance together with the valve, and it also transfers the heat of the valve head.

气门座可以直接在汽缸盖或汽缸体上加工而成。为了提高气门座表面的耐磨性，有时采用耐热钢、球墨铸铁或合金铸铁制成单独的零件，然后压入相应的孔中。这个零件即称为气门座圈。铝制汽缸盖或汽缸体进、排气门都必须采用气门座圈。对于强化内燃机，排气门热负荷高、磨损严重，所以排气门座通常都采用气门座圈。有的增压内燃机，由于进气管中无真空度，所以进气门处得不到机油的润滑而排气门处由于有废气中的油烟可起到润滑作用，所以进气门座有座圈，而排气门座则没有。

The valve seat can be machined directly on the cylinder head or cylinder block. In order to improve the wear resistance of the valve seat surface, separate parts are sometimes made of heat-resistant steel, nodular cast iron or alloy cast iron, and then pressed into the corresponding holes. This part is called the valve seat ring. Aluminum cylinder head or cylinder block inlet and exhaust valves must adopt valve seat ring. For enhanced internal combustion engines, the exhaust valve has high heat load and serious wear, so the exhaust valve seat usually adopts valve seat ring. In some turbocharged internal combustion engines, there is no vacuum in the intake pipe, so the intake valve can not be lubricated by engine oil, while the exhaust valve can be lubricated by the oil fume in the exhaust gas, so the intake valve seat has a seat ring, while the exhaust valve seat does not.

采用气门座圈的优点是提高了座面的耐磨和寿命，更换和维修也比较方便。缺点是传热条件差，加工要求高，气门座圈如工作时松脱则会造成事故。

The valve seat ring has the advantages of improving the wear resistance and service life of the seat surface, and it is also convenient to replace and maintain. The disadvantages are poor heat transfer conditions and high processing requirements. If the valve seat ring is loose during operation, it will cause accidents.

气门座圈的外表面有制成圆锥形或圆柱形两种。锥形表面压入座圈孔时，必须按规定的冲力将其压紧。气门座圈如压入铝合金汽缸中时，其配合表面常制成沟槽，当气门座圈压入后，少量铝金属会挤入沟槽中，在对气门座孔扩口时也会促使铝合金挤入，以提高座圈在座孔中的紧固程度，防止松脱

The outer surface of the valve seat ring can be made into a cone or a cylinder. When the conical surface is pressed into the seat ring hole, it must be pressed according to the specified impulse. When the valve seat ring is pressed into the aluminum alloy cylinder, its mating surface is often made into a groove. When the valve seat ring is pressed in, a small amount of aluminum metal will squeeze into the groove. When the valve seat hole is flared, it will also promote the aluminum alloy to squeeze in, so as to improve the fastening degree of the seat ring in the seat hole and prevent loosening

气门座紧压在汽缸盖的座孔中，磨损后以更换。气门锥面是气门与气门座之间的配合面，气门的密封性就是依靠两个表面严密贴合来保证的。为了保证密封，每个气门和气门座都要配对研磨，研磨后气门不能互换。

The valve seat is tightly pressed in the seat hole of the cylinder head and can be replaced after wear. The valve cone is the mating surface between the valve and the valve seat. The tightness of the valve depends on the close fitting of the two surfaces. In order to ensure sealing, each valve and valve seat shall be matched and ground. After grinding, the valves cannot be interchanged.