Vacuum control valves

A vacuum control valve, comprising

• a valve body including a wall having a smooth sealing surface thereon,
• said wall having a vacuum supply port and a vacuum utilization port extending therein from said sealing surface,
• means on said body for establishing a vacuum supply connection to said vacuum supply port,
• means on said body for establishing a vacuum utilization connection to said vacuum utilization port,
• a movable valve member movable along said sealing surface and including a soft resilient sealing member having a slidable sealing engagement with said sealing surface, and
• means guiding said valve member for movement along a predetermined path along said sealing surface of said wall,
• said sealing member of said valve member having passage means therein for selectively establishing communication between said vacuum supply port and said vacuum utilization port in at least one position of said valve member along said path,
• each of said ports comprising an opening with a tapered portion extending into said wall from said sealing surface,
• said tapered portion being at the intersection between said opening and said sealing surface to avoid the formation of any burr at said intersection,
• said tapered portion being of its maximum size at said sealing surface and tapering to a smaller size as said opening extends into said wall from said surface.