Throttle-valve control apparatus for spark-ignition two-cycle engines

A throttle-valve control apparatus for an AR-combustible spark-ignition two-cycle engine wherein, at least in a region of light-load operations, a compression-start pressure is controlled in order to let a fresh air/fuel mixture in a combustion chamber self-ignite so as to undergo active thermal atmosphere combustion, said throttle-valve control apparatus comprising:

• a throttle valve fixed in an air intake passage;
• a throttle-valve operation member for manually operating said throttle valve;
• a throttle-valve-closing-direction limiting means for selectively limiting a closing direction of said throttle valve so as to prevent said throttle valve from being closed beyond a predetermined amount;
• and
• throttle-valve-opening-limit control means for controlling said throttle-valve-closing-direction limiting means by determining whether a current state is a state for operating said AR-combustible spark-ignition two-cycle engine by combustion resulting from spark ignition or a state for operating said AR-combustible spark-ignition two-cycle engine by AR-combustion resulting from self-ignition at a controlled ignition time, and either actuating said throttle-valve-closing-direction limiting means so as to prevent said throttle valve from being closed beyond the predetermined amount if said current state was determined to be a state for operating said AR-combustible spark-ignition two-cycle engine by combustion resulting from spark ignition or placing said throttle-valve-closing-direction limiting means in a non-operative state so as to allow said throttle valve to be closed more than said predetermined amount if said current state was determined to be a state for operating said AR-combustible spark-ignition two-cycle engine by AR-combustion resulting from self-ignition at a controlled ignition time.

A throttle-valve control apparatus for an AR-combustible spark-ignition two-cycle engine wherein, at least in a region of light-load operations, a compression-start pressure is properly controlled in order to let a fresh air/fuel mixture in a combustion chamber self-ignite so as to undergo active thermal atmosphere combustion, said throttle-valve control apparatus comprising:

• a throttle valve fixed in an air intake passage;
• a throttle-valve operation member for manually operating said throttle valve;
• a throttle-valve opening means for opening said throttle valve in accordance with amounts of manual operation of said throttle-valve operation member;
• and
• a throttle-valve-opening control means for driving said throttle-valve opening means by determining whether a current state is a state for operating said AR-combustible spark-ignition two-cycle engine by combustion resulting from spark ignition or a state for operating said AR-combustible spark-ignition two-cycle engine by AR-combustion resulting from self-ignition at a controlled ignition time, and setting a lower-limit value of the opening of said throttle valve resulting from manual operations of said throttle-valve operation member small in comparison with a lower-limit value of those in a state for operating said AR-combustible spark-ignition two-cycle engine by ordinary combustion resulting from spark ignition if said current state was determined to be a state for operating said AR-combustible spark-ignition two-cycle engine by AR combustion resulting from self-ignition at a controlled ignition time.