When the engine runs in compression stroke and power stroke, the valves must close tightly on their seats to produce a gas-tight seal and thus prevent the gases escaping from the combustion chamber.
When the engine runs in compression stroke and power stroke, the valves must close tightly on their seats to produce a gas-tight seal and thus prevent the gases escaping from the combustion chamber.
当发动机处于压缩行程和做功行程时，阀门必须紧紧地关闭以产生一个不透气的气封，以防止气体逃离燃烧室。