| 摘要 |
A blower unit for a vehicle HVAC system, which is operable in one of a fresh air mode, a recirculation air mode and a mixture mode, comprises a housing defining an exterior fresh air intake aperture and an interior recirculation air intake aperture. A suction passage is in communication with both the exterior and interior air intake apertures. A first door is operably associated with the exterior air intake aperture for selectively opening and closing the exterior air intake aperture. A second door operably associated with the interior air intake aperture for selectively opening and closing the interior air intake aperture. The first and second doors are movable independent of each other. A partition is located in the suction passage for at least partially dividing the suction passage. The partition is selectively engaged by at least one of the first and second doors depending on the mode of the HVAC system. In the mixture mode, the first door is configured to control ram pressure as vehicle speed increases to maintain a predetermined airflow ratio between fresh air flowing into the housing via the exterior air intake aperture and recirculation air flowing into the housing via the interior air intake aperture.
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