Pressure wave valve

The invention relates to a valve for protecting against pressure waves in order to prevent unacceptable air pressures entering vehicles. Valves for protecting against pressure waves serve, in high speed trains, to prevent pressure surges resulting from trains passing one another, travelling through tunnels and the like from affecting the passengers unpleasantly by rapidly closing the fresh air vents. The invention disclosed in Claim 1 is based on the problem of providing a valve for protecting against pressure waves which ensures high functional reliablility despite the aforesaid environmental influences and at the same time ensures that the fresh air which is to be fed to the passengers in accordance with hygiene regulations is controlled. This problem is solved by the measures of Claim 1. Advantageous refinements of the invention are disclosed in Claims 2 to 6.