Vacuum generator in combustion engine

A vacuum generator in a combustion engine of the type that an idling air passage incorporating an idle speed control valve for controlling the idling rotational speed of said combustion engine is connected to a suction pipe to bypass a throttle valve arranged in said suction pipe, said vacuum generator including:

• conduit means for leading the intake negative pressure of said combustion engine to a negative pressure device through a check valve;
• and
• an ejector for flowing therethrough a part of the intake air volume toward said combustion engine to generate a negative pressure at a vacuum takeout port thereof and for utilizing the negative pressure generated at said vacuum takeout port to increase the absolute value of the negative pressure led to said negative pressure device, said ejector being arranged in said idling air passage at the downstream of said idle speed control valve in serial relation to the same so that the air flow from an inflow port to an outflow port of said ejector is inhaled into a combustion chamber of said combustion engine.