1. Multiple valves are put into work separately;

  (1) The valve is controlled to open or close under the set working conditions by cam or rocker arm.

  (2) A rotary valve is arranged on the intake passage to open or close the intake passage of the valve according to the set working condition. This structure is simpler to control than the cam and the rocker arm.

2. Variable inlet system;

  (1) Double pulse intake system.

  (2) Four-valve two-stage intake system.

  (3) Three-stage air intake system.

Double pulse intake system

   a) low speed section (n<4400r/min); b) high speed section (n>4400r/min)

    When the power valve in the intake pipe is closed, the variable intake pipe volume and the intake pipe with a total length of about 70 cm can form a resonant intake pressure wave at the engine speed n=3300r/min, which improves the charging efficiency and makes the torque reach Maximum value. When the engine speed is greater than 4000r/min, an effective intake pressure wave cannot be formed in the intake pipe, so that the power valve is opened and the two intermediate intake passages are connected into one body. Optimized to select the volume of the branch pipe connected to each cylinder and the main pipe, the high-speed (such as: n = 4400r / min) resonant intake pulse wave can be formed, so that the torque value reaches a higher value. Therefore, the torque curve changes gently in the range of n=1500 to 5000r/min.

The failure mode of the valve:

   Valve breakage often occurs where the neck and the head are welded, and the concentration of welding stress is the main cause of the breakage of the valve here;

   When the valve is worn, the valve stem is continuously rubbed during the movement of the valve guide, and the lubrication condition is poor, and the dust abrasive and the carbon depositing glue are mixed, so that both are worn;

Valve carbon deposit;

Valves in special environments have poor corrosion resistance, such as valves on ships;