Engine intake and exhaust system with switchable mode

The invention discloses an engine intake and exhaust system with the switchable mode. An intake main pipe connected with an intake manifold is branched into a first intake branch and a second intake branch, an exhaust main pipe connected with an exhaust manifold is branched into a first exhaust branch and a second exhaust branch, and a compressor and a turbine are arranged on the first intake branch and the first exhaust branch, so that a turbine pressurizing intake and exhaust loop is formed; the second intake branch and the second exhaust branch are arranged to a natural suction intake and exhaust loop; and through control over intake valves and exhaust valves on the intake branches and the exhaust branches, switching between the turbine pressurizing intake and exhaust loop and the natural suction intake and exhaust loop is controlled, and the requirement of an engine for intake and exhaust modes under different working conditions is met. 本发明公开了种可切换模式的发动机进排气系统,将与进气岐管连接的进气总管分支成第进气分支、第二进气分支，将与排气岐管连接的排气总管分支成第排