In view of the foregoing, {HEAD ~ the invention} provides {TAIL ~ a control valve} including a negative pressure chamber defined within a housing and in which a negative pressure is maintained, a variable pressure chamber formed within the housing, an atmosphere chamber formed within the housing and into which the atmosphere is introduced, a valve mechanism disposed within the housing for switching communication between the individual chambers, and a solenoid for operating the valve mechanism 
In view of the foregoing , { HEAD ~ the invention } provides { TAIL ~ a control valve } including a negative pressure chamber defined within a housing and in which a negative pressure is maintained , a variable pressure chamber formed within the housing , an atmosphere chamber formed within the housing and into which the atmosphere is introduced , a valve mechanism disposed within the housing for switching communication between the individual chambers , and a solenoid for operating the valve mechanism
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