Abstract:
A blower unit for a vehicle including a fan, a motor, a scroll case, a cooling chamber, a first partition, and a second partition. The fan is configured to generate airflow. The motor is connected to the fan. The scroll case accommodates the fan. The cooling chamber is connected to the scroll case and defines a cooling path for guiding airflow from the fan to the motor. The first partition is arranged in the cooling path. The second partition is arranged in the cooling path spaced apart from the first partition.

Description:
FIELD 
     The present disclosure relates to a scroll type blower unit for a vehicle. 
     BACKGROUND 
     A blower unit for a vehicle inherently generates noise. Such noise may contain undesirable high frequency noise. When the blower unit is running at low speed, the undesirable high frequency noise may be readily perceived by a person in a vehicle cabin. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     The present teachings provide for a blower unit for a vehicle. The blower unit includes a fan, a motor, a scroll case, a cooling path, a first surface, and a second surface. The fan is configured to generate air flow. The motor is connected to the fan. The scroll case accommodates the fan. The cooling path is connected to the scroll case and guides a part of the air flow from the fan to the motor. The first surface is accommodated in the cooling path and is generally perpendicular to the part of the airflow directed to the motor. The second surface is accommodated in the cooling path, and is substantially parallel to the first surface. The first surface and the second surface at least partially overlap each other in a direction of the airflow directed to the motor. The first and the second surfaces define a first gap therebetween. 
     The present teachings also provide for a blower unit for a vehicle that includes a fan, a motor, a scroll case, a cooling chamber, a first partition and a second partition. The fan is configured to generate airflow. The motor is connected to the fan. The scroll case accommodates the fan. The cooling chamber is connected to the scroll case and defines a cooling path for guiding airflow from the fan to the motor. The first partition is arranged in the cooling path. The second partition is arranged in the cooling path spaced apart from the first partition. 
     The present teachings further provide for a blower unit for a vehicle that includes a fan, a motor, a scroll case, a cooling chamber, a sloped surface, a first partition, and a second partition. The fan is configured to generate airflow. The motor is connected to the fan and seated within a motor housing. The scroll case accommodates the fan. The cooling chamber is connected to the scroll case and defines a cooling path for guiding airflow from the fan to the motor. The sloped surface of the cooling chamber extends between an outer peripheral portion of the scroll case to an edge of the motor housing. The first partition is arranged in the cooling path and extends from the scroll case. The second partition is arranged in the cooling path spaced apart from the first partition and extends from one of the scroll case or the sloped surface. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a cross sectional view of a blower unit according to a first embodiment; 
         FIG. 2  is an isometric view of a cooling path according to the first embodiment; 
         FIG. 3  is an isometric view of the cooling path, a fan, and a motor housing of the first embodiment; 
         FIG. 4  is an isometric view of a fan and motor housing assembly, and a scroll case of the first embodiment; 
         FIG. 5  is a cross sectional view of the blower unit of the first embodiment taken along line B-B′ of  FIG. 1  in the direction of arrows A; 
         FIG. 6  is a graph showing noise level created by a brush motor at low speed; 
         FIG. 7  is a graph showing noise reduction effect by a certain length of silencing chamber; 
         FIG. 8  is a cross sectional view of a blower unit for a vehicle according to a second embodiment of the present teachings; 
         FIG. 9  is a graph showing noise reduction effect by multiple lengths of multiple silencing chambers; 
         FIG. 10  is a cross sectional view of a blower unit for a vehicle according to a third embodiment of the present teachings; and 
         FIG. 11  is a cross sectional view of a blower unit for a vehicle according to a fourth embodiment of the present teachings. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
       FIG. 1  is a cross sectional view of a blower unit  100  for a vehicle according to a first embodiment of the present teachings. The blower unit  100  comprises a fan  102 , a motor  104 , a scroll case  106 , and a cooling chamber defining a cooling path  108 . The fan  102  is a centrifugal multi-blade type fan. The fan  102  is connected to the motor  104 . The motor  104  is a brush type motor. The brush type motor comprises a brush and a commutator. The fan  102  creates airflow when rotated by the motor  104 . 
     The motor  104  is accommodated in a motor housing  110 . The motor housing  110  defines an inner cylindrical surface  112 . The scroll case  106  accommodates the fan  102 . The scroll case  106  further defines a fresh air inlet  114 , a recirculation air inlet  116 , and an air outlet  118  (not shown in  FIG. 1 , see  FIGS. 4 and 5 ). The blower unit  100  intakes air from the fresh air inlet  114  or the recirculation air inlet  116 . In this embodiment, the fresh air inlet  114  and the recirculation air inlet  116  are alternatively opened and closed by a door  120 . 
     The cooling path  108  is connected to the scroll case  106  at a bottom surface  122  of the scroll case  106 . The cooling path  108  extends from an outer peripheral portion  124  of the scroll case  106  to the motor  104 . The scroll case  106  has an aperture  126  on its side surface  128 . A part of the airflow is directed into that aperture  126 . An upstream side of the cooling path  108  communicates with a space  130  located at a downstream side of the aperture  126 . A downstream side of the cooling path  108  communicates with the inner side of the motor housing  110 . Thus, the cooling path  108  guides a part of the airflow to the motor  104 . The cooling path  108  defines a slope  132 . The slope  132  declines from the outer peripheral portion  124  of the scroll case  106  to an edge  134  of the motor housing  110 . The airflow directed to the motor  104  goes through the motor housing  110  and enters the scroll case  106  again. 
     A first flat surface  136  is accommodated in the cooling path  108 . The first flat surface  136  in this embodiment is generally perpendicular to a flow direction of the part of the airflow directed to the motor  104 , but the angle of the first flat surface  136  may be inclined as well. In this embodiment, the first flat surface  136  forms a part of the motor housing  110 . The first flat surface  136  is provided on one side of a partition or wall  138  (depicted in  FIG. 2 ). The wall  138  provides a curved surface  140  on the other side of the first flat surface  136 . In another embodiment, the first flat surface  136  does not need to be a part of the scroll case  106  or cooling path  108 . 
     A second flat surface  142  of a second partition or wall is accommodated in the cooling path. The second flat surface  142  is substantially parallel to the first flat surface  136 . The second flat surface  142  protrudes from the slope  132  into the cooling path  108 . The first flat surface  136  and the second flat surface  142  at least partially overlap each other in a direction of the airflow. There is a first gap (g 1 ) between the first flat surface  136  and the second flat surface  142 , as illustrated in  FIG. 1  for example. 
       FIG. 2  further depicts a perspective view of the cooling path  108  in the first embodiment. In this embodiment, the cooling path  108  is a separate part from the scroll case  106 .  FIGS. 3 and 4  are isometric views of the cooling path  108 , the fan  102 , the motor housing  110 , and the scroll case  106  in the first embodiment. The cooling path  108  is attached to the motor housing  110  and scroll case  106  by clamps  144 .  FIG. 5  is a cross sectional view of the blower unit  100  along dashed line B-B′ viewing from the direction of arrow A depicted in  FIG. 1 . The curved surface  140  corresponds to the inner cylindrical surface  112 . 
       FIG. 6  is a graph showing noise level created by a brush motor at low speed. The brush motor typically makes noise at 2 to 10 kHz high frequency bands. The driver may easily perceive such high frequency band noise. In this disclosure, the first flat surface  136  and the second flat surface  142  cooperatively provide a narrow noise reduction chamber, gap (g 1 ), in the cooling path  108 . As shown in  FIG. 7 , the noise reduction effect relates to the chamber length. The length of the chamber (L) is defined by the distance between the flat surfaces. The noise reduction effect has Maximum/peaks calculated by n*c/(4 L), and Pockets/troughs appear at n*c/(2 L) between the Maxima/peaks, where n is an integer, c is velocity of sound, and L is length of the chamber. 
     It is preferable that the cooling path  108  defines a narrow chamber gap (g 1 ), small enough to preclude the above Pockets/troughs from an assumed noise range. For example, if the chamber gap (g 1 ) is set to be less than 1.8 cm, the Pockets/troughs will not appear until about 9 kHz. Thus, the high frequency noise created by brush motor noise may be effectively suppressed by the narrow chamber gap (g 1 ) at all the Maxima/peaks. 
     Second Embodiment 
       FIG. 8  is a cross sectional view of a blower unit  100  in the second embodiment. In the second embodiment, the blower unit  100  for a vehicle further includes a third flat surface  146  or a third partition or wall. The third flat surface  146  is accommodated in the cooling path  108 , and is substantially parallel to the second flat surface  142 . The second flat surface  142  and the third flat surface  146  at least partially overlap each other, and define a second gap (g 2 ) between them. The distance between the first flat surface and the second flat surface (the first gap g 1 ) is different from the distance between the second flat surface and the third flat surface (the second gap g 2 ). More specifically, in this embodiment, the first gap g 1  is larger than the second gap g 2 . In this embodiment, the first flat surface  136  is provided by the outer wall of the motor housing  110 . 
       FIG. 9  shows noise reduction effect by multiple lengths of multiple chambers. Like the configuration depicted in  FIG. 8 , multiple chambers will provide a broad band frequency noise reduction effect. 
       FIG. 10  is a cross sectional view of a blower unit  100  according to a third embodiment of the present teachings. In this third embodiment, the second flat surface  142  and the third flat surface  146  protrude from the bottom surface of the scroll case  106 . In this embodiment, the first gap g 1  is smaller than the second gap g 2 . 
       FIG. 11  is a cross sectional view of a blower unit  100  for a vehicle according to a fourth embodiment of the present teachings. In this fourth embodiment, the second flat surface  142  protrudes from the slope  132  of the cooling path  108 , and the third flat surface  146  protrudes from the bottom surface  122  of the scroll case  106 . In this embodiment, the second gap g 2  is defined between the first flat surface  136  and the third flat surface  146 . The second gap g 2  is larger than the first gap g 1 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.