Automotive HVAC Diffuser With Cooperating Wall Guide And Vane
A case for an HVAC system has at least two molded shells joined together along a parting line to enclose a heat exchanger chamber, a blower chamber, and a diffuser section. The diffuser section includes a floor, a ceiling, an outer wall, and an inner wall around a longitudinal axis. The walls provide an airflow path through the diffuser between the blower and heat exchanger chamber, and the airflow path makes a substantially right angle turn into the heat exchanger chamber which results in a tendency to create a high flow region at the outer wall because of centrifugal effects. The outer wall is shaped to form a wall guide partially projecting into the airflow path in the diffuser, wherein the wall guide has an upstream encroaching surface and a downstream retreating surface so that a portion of the guided air is directed from the outer wall toward the inner wall. At least one of the floor or the ceiling includes a vane projecting into and deflecting the guided air in the airflow path, wherein the vane has an upstream end proximate to the wall guide and a downstream end extending toward the heat exchanger chamber for initiating a portion of the substantially right angle turn for a portion of the airflow.
Latest AUTOMOTIVE COMPONENTS HOLDINGS, LLC Patents:
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCHNot Applicable.
BACKGROUND OF THE INVENTIONThe present invention relates in general to a case for an automotive HVAC system, and, more specifically, to wall guide and vane features for improving air flow into an evaporator core.
In a typical automotive HVAC system, a blower delivers fresh or recirculated air to heat exchangers (e.g., an evaporator) which is then distributed to the passenger cabin via ducts. A diffuser couples the air stream from the blower to the evaporator. Due to space requirements, the diffuser turns the air stream by about 90° for delivery to the evaporator. Conventional blower/diffuser combinations produce a non-uniform flow that tends to produce high flows on the outer periphery of the diffuser due to centrifugal forces, and the high flow becomes concentrated at one end of the evaporator.
A uniform velocity distribution at the diffuser outlet and into the evaporator is very desirable to ensure efficient evaporator performance, higher total air flow, and reduced noise generation as the air passes through the evaporator core. Prior attempts to improve the uniformity of the air flow have included the addition of aerodynamic vanes in the interior or at the walls of the diffuser.
The diffuser is normally made as a molded plastic part. The height of interior vanes from a corresponding wall have been restricted due to limitations in the molding process and limitations associated with handling of the part after molding (e.g., breakage of the vanes). Therefore, vanes can affect the air flow near to the diffuser walls but are less able to affect air flow near the midline of the diffuser. Furthermore, the die draw of the molding process does not allow vanes to extend from walls that are perpendicular to one another (i.e., vanes cannot extend from both the curved outer peripheral wall and either of the transverse (i.e., floor and ceiling) walls in the same molded section).
For similar reasons, structures built directly into the side walls have a greater influence on air flow in the regions of those walls. Prior art systems have, nevertheless, achieved some improvements in flow uniformity using vanes and wall structures to diffuse the air stream. However, it would be desirable to reduce the complexity and to increase the efficiency of such structures.
SUMMARY OF THE INVENTIONThe present invention overcomes limitations of the prior art by combining effects of a wall guide and a vane together to achieve uniform airflow across the evaporator core.
In one aspect of the invention, a case for an HVAC system in a transportation vehicle comprises at least two molded shells joined together along a parting line to receive a heat exchanger and a blower. The shells enclose a heat exchanger chamber, a blower chamber, and a diffuser section for guiding air from the blower chamber to the heat exchanger chamber. The diffuser section includes a floor, a ceiling, an outer wall, and an inner wall around a longitudinal axis between an inlet and an outlet. The walls provide an airflow path through the diffuser between the blower and heat exchanger chamber, and the airflow path makes a substantially right angle turn into the heat exchanger chamber which results in a tendency to create a high flow region at the outer wall because of centrifugal effects. The outer wall is shaped to form a wall guide partially projecting into the airflow path in the diffuser, wherein the wall guide has an upstream encroaching surface and a downstream retreating surface so that a portion of the guided air is directed from the outer wall toward the inner wall. At least one of the floor or the ceiling includes a vane projecting into and deflecting the guided air in the airflow path, wherein the vane has an upstream end proximate to the wall guide and a downstream end extending toward the heat exchanger chamber for initiating a portion of the substantially right angle turn for a portion of the airflow.
Referring now to
Diffuser section 13 includes an outer wall 15, an inner wall 16, a floor 17, and a ceiling (not shown) that surround a generally longitudinal axis of diffuser section 13 that extends between an inlet from the blower section 11 and an outlet to evaporator section 12. Due to centrifugal affects, a region of high flow is generally associated with outer wall 15 which results in non-uniform entry of the air flow into evaporator section 12. To improve uniformity and to reduce the generally high flow along outer wall 15, the present invention employs a wall guide 20 and a vane 21 for interacting with the guided air 14 and redirecting it in a beneficial manner.
Wall guide 20 is shown in greater detail in
One embodiment of a wall guide 35 is shown in greater detail in
The shape of downstream surface 37 is less critical. As shown in
Use of a wall guide together with a vane is shown in
The cross-sectional shape of the vane may be streamlined as shown in
Vane 93 extends to a height 97 above the floor. Parting line 96 is at a height 98 above the floor. The height of a vane may typically be limited to about 50 to about 75 millimeters. This may comprise about 60% to 70% of the distance of the floor or ceiling to the parting line. As a result, about 30% to 40% or more of the height of the airflow between floor and ceiling cannot be effectively shaped by the vanes. Thus,
Claims
1. A case for an HVAC system in a transportation vehicle, comprising at least two molded shells joined together along a parting line to receive a heat exchanger and a blower, wherein the shells enclose a heat exchanger chamber, a blower chamber, and a diffuser section for guiding air from the blower chamber to the heat exchanger chamber;
- wherein the diffuser section includes a floor, a ceiling, an outer wall, and an inner wall around a longitudinal axis between an inlet and an outlet;
- wherein the walls provide an airflow path through the diffuser between the blower and heat exchanger chamber, and wherein the airflow path makes a substantially right angle turn before entering the heat exchanger chamber which results in a tendency to create a high flow region at the outer wall because of centrifugal effects;
- wherein the outer wall is shaped to form a wall guide partially projecting into the airflow path in the diffuser, wherein the wall guide has an upstream encroaching surface and a downstream retreating surface so that a portion of the guided air is directed from the outer wall toward the inner wall; and
- wherein at least one of the floor or the ceiling includes a vane projecting into and deflecting the guided air in the airflow path, wherein the vane and wall guide cooperate to mutually direct the guided air from the outer wall toward the inner wall.
2. The case of claim 1 wherein the vane extends to a first height which is less than about 70 percent of a height of the parting line, and wherein the wall guide spans a region around the parting line.
3. The case of claim 1 wherein the vane has an upstream end proximate to the wall guide and a downstream end extending toward the heat exchanger chamber for initiating a portion of the substantially right angle turn for a portion of the airflow.
4. The case of claim 1 wherein at least a portion of the upstream end of the vane extends substantially parallel to the local flow so that a region of the airflow path between the vane and the downstream returning surface has an increasing cross-sectional area that causes guided air passing through the region to have a reduction in speed by the Bernoulli Effect.
5. The case of claim 1 wherein the downstream end of the vane has an extended teardrop shape.
6. The case of claim 1 wherein the upstream encroaching surface of the wall guide includes a generally concave shape with a radius of curvature in the range of about 15 to about 100 millimeters.
7. The case of claim 1 wherein the downstream retreating surface of the wall guide includes a generally concave shape with a radius of curvature greater than about 100 millimeters.
8. The case of claim 1 wherein the wall guide further includes a transition between the upstream encroaching surface and the downstream retreating surface having a generally convex shape with a radius of curvature less than about 40 millimeters.
9. The case of claim 1 wherein the cooperation of the wall guide and vane is comprised of the wall guide and vane being disposed in a side-by-side relationship to define a curved air channel, whereby the guided air is deflected along a curving trajectory toward the heat exchanger chamber.
Type: Application
Filed: Jan 4, 2011
Publication Date: Jul 5, 2012
Applicant: AUTOMOTIVE COMPONENTS HOLDINGS, LLC (Dearborn, MI)
Inventors: Vivek A. Jairazbhoy (Farmington Hills, MI), Mehran Shahabi (Ypsilanti, MI)
Application Number: 12/984,178
International Classification: F24H 9/02 (20060101); F24F 7/007 (20060101);