Spark timing control device for use in internal combustion engines

Claim 1

A spark timing control device for use in an internal combustion engine, comprising: an intake passage in said engine provided with an intake port; a pressure control valve operative so that when an input vacuum applied thereto is not higher than a given vacuum level, an output vacuum therefrom remains at a zero level, and when an input vacuum applied thereto is not lower than said given vacuum level, an output vacuum therefrom will be a product of a proportional constant and the difference between said input vacuum and said given vacuum level; a vacuum advance control mechanism; and, a pressure responsive valve having a first input port, a second input port, an output port and a control vacuum port, including means for selectively connecting said first input port or said second input port to said output port in response to the magnitude of a vacuum supplied to said control vacuum port, said intake port being connected to said control vacuum port and said first input port in said pressure responsive valve as well as to the input side of said pressure control valve; the output side of said pressure control valve being connected to said second input port in said pressure responsive valve, and said output port in said pressure responsive valve being connected to said vacuum advance control mechanism.