Heater unit for air conditioning system for automotive vehicles

A heater unit for use in an air conditioning system for automotive vehicles, which comprises:

• (1) a casing comprising a box-shaped body having a ceiling wall, a rear side wall, a front side wall, a bottom wall and opposite lateral side walls and a tubular projection having a ceiling wall and a bottom wall and having a substantially rectangular cross section, said tubular projection extending laterally from one of said lateral side walls at a location biased toward said ceiling wall and rear side wall of said box-shaped body, said tubular projection having an air inlet formed in an end face thereof, said tubular projection having a cross sectional area smaller than that of said one lateral side wall, said ceiling wall having a defroster air outlet, said front side wall having an upper or face air outlet, said opposite lateral side walls having a floor air outlet opening in lower portions thereof;
• (2) a heater core horizontally disposed within said casing, said heater core being arranged on a line extending from said air inlet of said tubular projection at a substantially vertically central portion of said one lateral side wall, said heater core having one side wall disposed in contact with said rear side wall of said casing and another side wall with the other lateral side wall of said casing, respectively, said heater core cooperating with said rear side wall, ceiling wall, front side wall and other lateral side wall of said casing to define a cold air and warm air mixing chamber in a zone immediately above said heater core, said upper or face air outlet and said defroster air outlet opening in said air mixing chamber;
• (3) a horizontal partition member horizontally extending at a level at least lower than the of said bottom wall of said tubular projection and joined to at least said rear side wall and said other lateral side wall;
• (4) a partition wall extending substantially vertically from said horizontal member and joined to said heater core at a side facing said air inlet, said vertical partition wall cooperating with said front side wall, bottom wall and opposite lateral side walls of said casing and said horizontal partition member to define an air guide passage communicating with said air mixing chamber, said floor air outlet opening in said air guide passage;
• (5) an air-mix damper vertically pivotally mounted on said heater core at said side facing said air inlet and extending from said heater core into said lateral projection, said air-mix damper having a free end disposed to be seated on said ceiling wall and bottom wall of said tubular projection, said air-mix damper and said heater core cooperating with said tubular projection, said ceiling wall, said rear side wall, said horizontal partition member and said vertical partition wall to define an upper air passage and a lower air passage for guiding air introduced in through said air inlet, said upper air passage extending substantially horizontally from said air inlet to said air mixing chamber, said lower air passage extending from said air inlet to a lower side of said heater core to allow air introduced thereinto to flow through said heater core upwardly thereof, whereby cold air delivered to said air mixing chamber through said upper air passage and warm air delivered to said air mixing chamber through said lower air passage and said heater core collide with each other at substantially right angles to be mixed together;
• (6) a first damper arranged to close selectively said upper or face air outlet and said defroster air outlet;
• (7) a second damper arranged to close only part of said defroster air outlet;
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• (8) a third damper arranged to close said air guide passage.