Sealing arrangement for a rotary slide valve

In an arrangement for providing a seal between a rotary slide valve supported in a slide valve housing and subjected to fluctuating pressures in an adjacent combustion chamber and a cylindrical profiled seal having a peripheral sliding surface at one end thereof which engages a counter surface of the slide valve and a first annular surface at the other end on which said fluctuating pressures act to urge the profiled seal in a direction toward the slide valve and increase the force between said peripheral sliding surface and said counter surface, and a peripheral ring positioned near said other end of said profiled seal for sealing an annular gap between the outer surface of said profiled seal and a mating cavity in said slide valve housing, the improvement comprising:

• at least one spring mounted in said slide valve housing and sealed from said combustion chamber arranged to urge said profiled seal towards said slide valve for generating sealing forces between said peripheral sliding surface and the counter surface of said slide valve,
• said peripheral sliding surface being disposed radially outwardly with respect to said first annular surface, and
• said profiled seal being shaped to have a second annular surface coaxial and axially aligned with the first annular surface, the second annular surface having an area approximately equal to the area of said first annular surface on which said fluctuating pressures act to urge the profiled seal in a direction away from the slide valve so as to counteract the pressures acting on said first annular surface whereby sealing forces between the sliding surface and the counter surface are provided substantially only by said spring.