Hot-wire air flowmeter control system for engine

Claim 1

A system for controlling a hot-wire air flowmeter including a hot wire provided for an internal combustion engine having an ignition switch and a canister for storing and supplying fuel evaporated from a fuel tank into an intake passage according to engine operating conditions, said control system comprising: (a) ignition detecting means for detecting whether the ignition switch is turned on or off; (b) engine stop detecting means for detecting whether the engine is running or stopped; and (c) air-flowmeter controlling means having: (1) air-flow measuring means for measuring the amount of air flowing through the intake passage on the basis of the amount of heat radiated from the hot wire when cooled by the air; (2) burning means for allowing a large current to pass through the hot wire for a fixed time period to heat up the hot wire for removal of contaminations sticked onto the hot wire; and (3) large-current controlling means responsive to said ignition detecting means and said engine stop detecting means for activating said burning means to allow a large current to pass through the hot wire for the fixed time period when a first predetermined time period has elapsed after said ignition detecting means detected that the ignition switch was turned off, only when said engine stop detecting means detects that the engine is running a second predetermined time period before said ignition detecting means detects that the ignition switch is turned off.

Claim 2

A system for controlling a hot-wire air flowmeter including a hot wire provided for an internal combustion engine having an ignition switch and a canister for storing and supplying fuel evaporated from a fuel tank into an intake passage according to engine operating conditions, said control system comprising: (a) ignition detecting means for detecting whether the ignition switch is turned on or off; (b) engine stop detecting means for detecting whether the engine is running or stopped; and (c) air-flowmeter controlling means having: (1) air-flow measuring means for measuring the amount of air flowing through the intake passage on the basis of the amount of heat radiated from the hot wire when cooled by the air; (2) burning means for allowing a large current to pass through the hot wire for a fixed time period to heat up the hot wire for removal of contaminations sticked onto the hot wire; and (3) large-current controlling means responsive to said ignition detecting means and said engine stop detecting means for activating said burning means to allow a large current to pass through the hot wire for the fixed time period when a first predetermined time period has elapsed after said ignition detecting means detected that the ignition switch was turned off, only when said engine stop detecting means detects that the engine is running a second predetermined time period before said ignition detecting means detects that the ignition switch is turned off.

Claim 6

A method of controlling a hot-wire air flowmeter including a hot wire provided for an internal combustion engine having an ignition switch and a canister for storing and supplying fuel evaporated from a fuel tank into an intake passage according to engine operating conditions, said control method comprising the following steps of: (a) checking whether the ignition switch is on or off; (b) if on, checking whether the engine is running or stopped; (c) if running, storing this engine-running condition in memory; (d) if stopped, storing this engine-stop condition in memory; (e) checking again whether the ignition switch is on or off; (f) if on, implementing the same steps from (b) to (e) above repeatedly at predetermined time intervals; (g) if off, checking whether the engine-running condition or the engine-stop condition is stored in memory; (h) if the engine-running condition is stored, allowing a large current to pass through the hot wire for a fixed time period to heat up the hot wire for removal of contaminations sticked onto the hot wire; and (i) if the engine-stop condition is stored, implementing the same stops from (a) to (g) above repeatedly.

Claim 7

A method of controlling a hot-wire air flowmeter including a hot wire provided for an internal combustion engine having an ignition switch and a canister for storing and supplying fuel evaporated from a fuel tank into an intake passage according to engine operating conditions, said control method comprising the following steps of: (a) checking whether the ignition switch is on or off; (b) if on, checking whether the engine is running or stopped; (c) if running, storing this engine-running condition in memory; (d) if stopped, storing this engine-stop condition in memory; (e) checking again whether the ignition switch is on or off; (f) if on, implementing the same steps from (b) to (e) above repeatedly at predetermined time intervals; (g) if off, checking whether the engine-running condition or the engine-stop condition is stored in memory; (h) if the engine-running condition is stored, allowing a large current to pass through the hot wire for a fixed time period to heat up the hot wire for removal of contaminations sticked onto the hot wire; and (i) if the engine-stop condition is stored, implementing the same stops from (a) to (g) above repeatedly.