Check valve used with vacuum system for an automotive vehicle

摘要

A vacuum system used with an automotive vehicle such that an appropriate negative pressure is maintained within the vacuum system in order to assure the function of the vacuum brake booster even when the vacuum clutch booster is defective with respect to airtightness. A vacuum system according to the present invention comprises a novel second check valve having an orifice formed in the poppet valve or in the valve body, being connected between the intake manifold and the vacuum clutch booster. The second check valve operates as an ordinary check valve in a normal condition but as an orifice in an abnormal condition to prevent the vacuum pressure in the system from being decreased quickly, without use of any conventional vacuum tank.