COMBUSTION TYPE POWER HEATER SYSTEM SYSTEM DESCRIPTION


  1. GENERAL


    1. While the 1ND-TV engine offer excellent combustion efficiency, it generates low levels of heat. Therefore, depending on the operating condition, the engine coolant temperature remains low, making it difficult to ensure proper heating. Thus, in order to provide adequate heating, a combustion heater is provided as optional equipment on the cold area specification LHD models for Europe.

    2. This heater system provides a combustion heater between the engine and the heater core. Air and fuel are introduced into the heater's combustion chamber, and a glow plug is used to ignite this mixture. By heating the engine coolant that flows around the combustion chamber, this system ensures proper heating.

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  2. COMBUSTION HEATER ASSEMBLY


    1. This system, which consists of a combustion heater, power heater switch, and a heater pump assembly, operates when the engine is idling and the power heater switch is turned on.


      • The combustion heater consists of a power heater ECU, flame sensor, surface sensor, control overheating sensor, glow plug, and air blower motor. It cannot be disassembled.

      • The power heater ECU in the combustion heater controls this system in accordance with the signals received from the sensors and switches.

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  3. OPERATION


    1. When the engine is idling, turning the power heater switch on causes the air fan to operate for several seconds for verification purposes. Then, the glow plug starts to preheat the combustion chamber. After that, the fuel pump and air fan turn on in order to start low combustion. The fuel pump speed is then increased in steps, and this is accompanied by a gradual increase in the speed of the air fan, thus leading to high combustion.

    2. When the ignition switch is turned off or the power heater switch is turned off, the fuel pump stops, causing the combustion to stop. For the purpose of after-purge, current is applied again to the glow plug, and the air fan is activated for several seconds. Then, the entire system comes to a stop.

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    3. While the system is in operation, it controls the fuel pump speed, switches between high combustion and low combustion, and always keeps the coolant temperature between 68°C (154.4°F) and 78°C (172.4°F). If the coolant temperature exceeds 78°C (172.4°F), the fuel pump stops automatically to stop the combustion. Thereafter, when the coolant temperature reaches 68°C (154.4°F) or below, ignition occurs again. The operation of the glow plug, the air fan, and the fuel pump during extinguishing and re-igniting is the same as when these are operated by switch as mentioned previously.

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  4. FAIL-SAFE


    1. If the glow plug breaks, the power heater ECU detects the breakage and stops the automatic operation to prevent combustion heater operation.

    2. If the temperature detected by the control overheating sensor or the surface sensor exceeds 125°C (257°F), the power heater ECU determines that the combustion heater is operating without engine coolant and automatically stops the system.

    3. If the difference in temperature detected by the control overheating sensor and the surface sensor exceeds 25°C (77°F), the power heater ECU determines that the flow volume of the engine coolant is insufficient and automatically stops the system.

    4. If the temperature of the exhaust gas detected by the flame sensor is low, the power heater ECU determines that a non-ignition or a misfiring condition exists and automatically stops the system.

    5. If an open or short circuit exists in the sensors or actuators, the power heater ECU automatically stops the system.

    6. If the air fan becomes seized, the power heater ECU automatically stops the system.