Air intake heating and diagnostic system for internal combustion engines

A method of warning a vehicle operator of a fault in an air intake heating system for supplying heated air to an internal combustion engine of the vehicle, said air intake heating system having means for sensing intake manifold air temperature, said engine having switch means for starting and stopping said engine,said switch means being switchable between "off", "on" and "crank" states, said method comprising the steps of:

• (1) switching said switch means from said "off" state to said "on" state;
• (2) sensing intake manifold air temperature;
• (3) comparing said sensed intake manifold air temperature to a first and second reference temperature;
• (4) warning said vehicle operator of one of
• (a) a first fault condition if said sensed intake manifold air temperature falls below said first reference temperature for at least a first predetermined time period, and
• (b) a second fault condition if said sensed intake manifold air temperature exceeds said second reference temperature for at least a second predetermined time period;
• and
• (5) continuously performing steps (2)-(4) from the time the switch means is switched on prior to starting said engine and during the time the engine is operating after the switch has been switched to the "crank" state until said switch means is switched to said "off" state to thereby stop said engine.

A diagnostic system for detecting faults in an air intake heating system for supplying heated air to an internal combustion engine of a vehicle, said air intake heating system having means for sensing intake manifold air temperature and producing a temperature signal corresponding thereto, means for sensing engine speed level and producing an engine speed signal corresponding thereto and means for heating said intake manifold air, said engine having switch means for starting and stopping said engine, said switch means being switchable between "off", "on" and "crank" states, said means for sensing intake manifold air temperature sensing an initial air temperature when said switch means is switched from said "off" state to said "on" state prior to starting said engine, said diagnostic system comprising:

• means for storing a number of temperature threshold levels, a predetermined time period and a number of flags;
• and
• controller means for detecting air intake heating system faults, said controller means receiving said temperature and engine speed signals and continuously computing the difference between said intake manifold air temperature and said initial temperature for a predetermined postheat time period, and
• storing a first flag within said storing means if said difference exceeds a particular one of said number of temperature threshold levels within said predetermined time period, and
• storing a second flag within said storing means if said difference has not exceeded said particular one of said number of temperature threshold levels within said predetermined time period;
• said controller means storing either of said first and second flags in accordance with said difference if said intake air temperature is below a first predetermined temperature and said engine speed is above a first predetermined RPM level, said controller means otherwise storing only said first flag within said storing means regardless of said difference if either said initial air temperature is above a first predetermined temperature or said engine speed is below a first predetermined RPM level.

A method of detecting faults in an air intake heating system for supplying heated air to an internal combustion engine of a vehicle, said air intake heating system having means for sensing intake manifold air temperature, means for sensing engine speed, means for heating said intake manifold air and a memory, said engine having switch means for starting and stopping said engine, said switch means being switchable between "off", "on" and "crank" states, said method comprising the steps of:

• (1) switching said switch means from said "off" state to said "on" state prior to starting said engine;
• (2) sensing an initial intake manifold air temperature when said switch means is switched from said "off" state to said "on" state;
• (3) sensing engine speed after starting said engine;
• (4) performing steps (5)-(7) if said initial intake manifold air temperature is below a predetermined temperature level and said engine speed is above a predetermined RPM level, and otherwise storing a first flag within said memory;
• (5) sensing air manifold temperature and determining the difference between said intake manifold air temperature and said initial intake manifold air temperature;
• (6) storing said first flag within said memory if said difference exceeds a predetermined temperature threshold level within a first predetermined time period;
• (7) storing a second flag within said memory if said difference does not exceed said predetermined temperature threshold level within said first predetermined time period;
• and
• (8) performing steps (5)-(7) for a second predetermined time period unless one of said first and second flags is stored within said memory.

An air intake heating and diagnostic system for use with a vehicle having an internal combustion engine, said system comprising:

• means for sensing intake manifold air temperature and producing a temperature signal corresponding thereto;
• means for starting and stopping said engine, said starting and stopping means being switchable between "off", "on" and "crank" states and producing an ignition signal corresponding to each of said states, said manifold air intake temperature sensing means sensing an initial intake manifold air temperature when said ignition signal is switched from said "off" state to said "on" state;
• means for warning said operator of said vehicle of a fault condition detected in said system;
• means for heating intake manifold air;
• and
• means for controlling said air intake heating means for a variable preheat time period prior to starting said engine, said controller means having a first input for receiving said temperature signal and a second input for receiving said ignition signal, said controller means receiving said temperature and ignition signals, and
• responding to a first fault condition by replacing said variable preheat time period with a predetermined preheat time period and activating said intake manifold air heating means, if said temperature signal falls below a first predetermined temperature level for at least a first predetermined time period, and
• responding to a second fault condition by activating said warning means, deactivating said intake manifold air heating means and ending said variable preheat time period, if said temperature signal exceeds a second predetermined temperature level for at least a second predetermined time period,
• said controller means activating said intake manifold air heating means for said variable preheat time period in accordance with predetermined ranges of said initial temperature if neither of said first and second fault conditions are detected within said variable preheat time period and said initial temperature is below a threshold temperature level.

A method of controlling an air intake heating system for an internal combustion engine of a vehicle for a variable preheat time period prior to starting said engine, said air intake heating system having means for sensing intake manifold air temperature, means for heating intake manifold air, means for warning an operator of said vehicle of a fault detected in said system and means for prompting said operator to wait for said variable preheat time period prior to starting said engine, said engine having switch means for starting and stopping said engine, said switch means being switchable between "off", "on" and "crank" states, said method comprising the steps of:

• (1) switching said switch means from said "off" state to said "on" state prior to starting said engine and sensing an initial intake manifold air temperature when said switch means is switched from said "off" state to said "on" state;
• (2) performing steps (3)-(13) for said variable preheat time period in accordance with said initial intake manifold air temperature, if said initial intake manifold air temperature is below a first predetermined temperature level;
• (3) activating said prompting means;
• (4) sensing said intake manifold air temperature and comparing said intake manifold air temperature to first and second reference temperatures;
• (5) performing steps (6)-(8) if said intake manifold air temperature falls below said first reference temperature for a first predetermined time period;
• (6) setting said variable preheat time period to a predetermined preheat time period;
• (7) activating said intake manifold air heating means;
• (8) continuously activating and deactivating said prompting means at a predetermined frequency;
• (9) performing steps (10)-(12) if said intake manifold air temperature exceeds said second reference temperature for a second predetermined time period;
• (10) deactivating said intake manifold air heating means and said prompting means if said intake manifold air heating means and said prompting means are activated;
• (11) activating said warning means;
• (12) ending said variable preheat time period;
• and
• (13 ) otherwise activating said intake manifold air heating means.

An air intake heating and diagnostic system for use with a vehicle having an internal combustion engine, said system comprising:

• means for sensing intake manifold air temperature and producing a temperature signal corresponding thereto;
• means for sensing engine speed and producing an engine speed signal corresponding thereto;
• means for starting and stopping said engine, said starting and stopping means being switchable between "off", "on" and "crank" states and producing an ignition signal corresponding to each of said states, said means for sensing manifold air temperature sensing an initial temperature when said starting and stopping means is switched from said "off" state to said "on" state prior to starting said engine;
• means for heating intake manifold air;
• and
• means for controlling said intake manifold air heating means for a predetermined postheat time period after starting said engine, said controller means having memory, a first input for receiving said temperature signal, a second input for receiving said engine speed signal and a third input for receiving said ignition signal, said controller means receiving said temperature, engine speed and iginition signals and activating said intake manifold air heating means for said predetermined postheat time period in accordance with predetermined ranges of said initial temperature and predetermined ranges of said engine speed if said initial temperature is below a first predetermined temperature and said engine speed is above a predetermined RPM level,
• said controller means further continuously computing the difference between said intake manifold air temperature and said initial temperature for the duration of said predetermined postheat time period, and
• storing a first flag within said memory if said difference exceeds a predetermined threshold temperature level, and
• storing a second flag within said memory if said difference has not exceeded said predetermined threshold temperature level within a first predetermined time period.

A method of controlling an air intake heating system for an internal combustion engine of a vehicle after starting said engine, said air intake heating system having means for sensing intake manifold air temperature, means for sensing engine speed, means for heating intake manifold air and electronic memory, said engine having switch means for starting and stopping said engine, said switch means being switchable between "off", "on" and "crank" states, said method comprising the step of:

• (1) switching said switch means from said "off" state to said "on" state prior to starting said engine and sensing an initial intake manifold air temperature when said switch means is switched from said "off" state to said "on" state;
• (2) sensing engine speed after starting said engine and performing steps (3)-(7) if said engine speed exceeds a predetermined RPM level and said initial intake manifold air temperature is below a first predetermined temperature level, and otherwise storing a first flag within said memory;
• (3) activating said intake manifold air heater means in accordance with predetermined ranges of said initial intake manifold air temperature and predetermined ranges of said engine speed;
• (4) continuously sensing said intake manifold air temperature;
• (5) determining the difference between said intake manifold air temperature and said initial intake manifold air temperature;
• (6) storing a first flag within said memory if said difference exceeds a predetermined threshold temperature;
• (7) storing a second flag within said memory if said difference does not exceed said predetermined threshold temperature within a first predetermined time period;
• and
• (8) performing steps (3)-(7) for a predetermined postheat time period unless one of said first and second flags is stored within said memory.

An air intake heating and diagnostic system for use with a vehicle having an internal combustion engine, said system comprising:

• at least one temperature sensor for sensing intake manifold air temperature and producing a temperature signal corresponding thereto;
• at least one engine speed sensor for sensing engine speed and producing an engine speed signal corresponding thereto;
• a switch for stating and stopping said engine, said switch being switchable between "off", "on " and "crank" states and producing an ignition signal corresponding to each of said states, said temperature sensor sensing an initial air temperature when said switch is switched from said "off" state to said "on " state prior to starting said engine;
• means for prompting and operator of said vehicle to wait a variable preheat time period after switching said switch from said "off" state to said "on" state before switching said switch from said "on" state to said "crank" state to thereby start said engine;
• means for warning said operator of said vehicle of a fault condition detected in said system;
• a number of intake manifold air heaters;
• and
• a controller for controlling said intake manifold air heaters, said controller having memory, a first input for receiving said temperature signal, a second input for receiving said ignition signal ad a third input for receiving said engine speed signal, said controller receiving said temperature, ignition and engine speed signals, and
• activating said warning means until said switch is switched to said "off" state if said temperature sensor is detected as being short circuited,
• activating said intake manifold air heaters and continuously activating and deactivating said prompting means at a predetermined frequency for a predetermined preheat time period if said temperature sensor is detected as being open-circuited,
• activating said intake manifold air heaters for said variable preheat time period in accordance with predetermined ranges of said initial temperature is said temperature sensor is detected as being neither of open-circuited and short-circuited within said variable preheat time period,
• activating said intake manifold heaters for a predetermined postheat time period after starting said engine in accordance with said predetermined ranges of said initial temperature and predetermined ranges of said engine speed, if said temperature sensor is not detected as being short-circuited,
• storing a "pass" flag within said memory if said intake manifold air heater are detected as operating during said predetermined postheat time period, and
• storing a "fail" flag within said memory if said intake manifold air heaters are detected as being inoperable during said predetermined postheat time period.

A method of controlling an air intake heating system for an internal combustion engine of a vehicle, said air intake heating system having means for sensing intake manifold air temperature, means for sensing engine speed, means for heating intake manifold air, means for warning an operator of said vehicle of a fault within said system and electronic memory, said engine having switch means for starting and stopping said engine, said switch means being switchable between "off", "on" and "crank" states, said system further having means for prompting said operator to wait before switching said switch means from said "on " state to said "crank" state, after switching said switch means from said "off" state to said "on" state prior to starting said engine, said method comprising the steps of:

• (1) switching said switch means from said "off" state to said "on" state prior to starting said engine;
• (2) sensing an initial intake manifold air temperature when said switch means is switched from said "off" state to said "on" state;
• (3) continuously monitoring said temperature sensor means for one of an open-circuit fault and a short-circuit fault;
• (4) performing steps (5)-(7) if said initial intake manifold air temperature is below a predetermined temperature;
• (5) activating said intake manifold air temperature heating mens, and continuously activating and deactivating said prompting means at a predetermined frequency, for a predetermined preheat time period and storing a first flag within said memory, if said open-circuit fault is detected;
• (6) activating said warning means until said switch means is returned to said "off" state, storing a second flag within said memory and deactivating said intake manifold air heating means, if said short-circuit fault is detected;
• (7) activating said intake manifold air heating means for a variable preheat time period in accordance with predetermined ranges of said initial temperature if either of said open-circuit fault and said short-circuit fault is detected within said variable preheat time period;
• (8) sensing engine speed and performing steps (9)-(11) if said engine speed exceeds a predetermined RPM level and said initial intake manifold air temperature is below said predetermined temperature;
• (9) activating said intake manifold air heater means for a predetermined postheat time period in accordance with predetermined ranges of sid initial temperature and predetermined ranges of said engine speed;
• (10) storing a third flag within said memory if said intake manifold air heater means is detected as operating during said predetermined postheat time period, and
• (11) storing a fourth flag within said memory if said intake manifold air heater means is detected as being inoperable during said predetermined postheat time period.