Use of fan shroud to ventilate engine compartment

A method and apparatus to ventilate an engine compartment of a vehicle.

FIELD OF THE INVENTION

The present disclosure relates to engine cooling systems. More particularly, the present disclosure relates to fan shrouds used in engine cooling systems to ventilate an engine compartment of a vehicle.

BACKGROUND OF THE INVENTION

Utility vehicles, such as tractors, motor graders, bulldozers, and skidders, are powered by internal combustion engines. Internal combustion engines generate a significant amount of heat during operation. To cool and protect the engine, engine cooling systems are provided. The engine cooling system may include a fan, a radiator, and liquid coolant. In operation, liquid coolant flows through the engine block to absorb heat from the engine. Then, the heated liquid coolant travels through the radiator while the fan directs cool, ambient air across the radiator to cool the liquid coolant. Finally, the cooled liquid coolant leaving the radiator is recirculated through the engine block.

SUMMARY

The present disclosure provides a method and apparatus to ventilate an engine compartment of a vehicle.

According to an embodiment of the present disclosure, a vehicle is provided including a chassis, at least one ground engaging mechanism configured to propel the chassis over the ground, an engine operatively coupled to the at least one ground engaging mechanism to power propulsion of the chassis, a baffle defining a vent aperture, and a cooling system separated from the engine by the baffle. The cooling system includes a heat exchanger, a shroud having an outer periphery that defines an opening, an inlet, and an outlet, the outer periphery of the shroud including a suction aperture in communication with the vent aperture of the baffle, and a fan received in the opening of the shroud for rotation therein, the fan being configured to draw air into the inlet of the shroud and into the suction aperture of the shroud, and also being configured to discharge air from the outlet of the shroud.

According to another embodiment of the present disclosure, a vehicle is provided including a chassis, at least one ground engaging mechanism configured to propel the chassis over the ground, an engine operatively coupled to the at least one ground engaging mechanism to power propulsion of the chassis, a heat exchanger coupled to the engine for cooling the engine, and a fan assembly. The fan assembly includes a first inlet configured to draw air across the heat exchanger and into the fan assembly, a second inlet configured to draw air across the engine and into the fan assembly, and an outlet configured to discharge air drawn into the fan assembly through the first and second inlets.

According to yet another embodiment of the present disclosure, a method is provided to ventilate an engine compartment of a vehicle. The method includes the steps of: providing a vehicle including an engine and a heat exchanger; directing a first air stream across the heat exchanger to cool the heat exchanger; directing a second air stream across the engine to cool the engine; combining the first and second air streams to produce a third air stream; and exhausting the third air stream from the vehicle.

DETAILED DESCRIPTION

Referring toFIG. 1, a utility vehicle in the form of skidder10is illustrated. Although the vehicle is illustrated and described herein as skidder10, the utility vehicle may include a motor grader, a tractor, a bulldozer, or another utility vehicle. Skidder10includes chassis12and ground engaging mechanism14. Ground engaging mechanism14may be capable of supporting chassis12and propelling chassis12across the ground. Although the illustrated skidder10includes wheels as ground engaging mechanism14, skidder10may include tracks, such as steel tracks or rubber tracks. Skidder10also includes multiple work tools, specifically a front-mounted blade16and a rear-mounted grapple18coupled to chassis12via grapple linkage20. Both blade16and grapple18are configured to move relative to chassis12to move material. For example, blade16may be used for leveling dirt and other materials and pushing over trees, and grapple18may be used for pulling tree stumps. The utility vehicle may be provided with other work tools, such as a bucket, a pallet fork, a bail lift, an auger, a harvester, a tiller, or a mower, for example. Skidder10further includes operator cab22. Operator cab22is provided with controls (not shown) to operate skidder10and protects the operator.

Referring next toFIGS. 2 and 3, the front end of skidder10includes hood30(shown in phantom) to enclose and protect internal combustion engine40and other vehicle components, including, for example, a charge air cooling system, a hydraulic system, a transmission system, an after-treatment system, and/or an exhaust system including a muffler. Hood30is supported by chassis12. Hood30may be a one-piece or multi-piece structure and may be constructed of metal, a polymer, or another suitable material. Hood30may include a hinged door (not shown) to provide access to internal combustion engine40. At least some walls of hood30may be screened or vented to permit airflow into and out of hood30. For example, hood30may include front grill32that is vented to permit airflow into and out of the front end of skidder10. Hood30may also include side grills34,34′, that are vented to permit airflow into and out of the sides of skidder10.

The vehicle components under hood30, including internal combustion engine40, may generate a significant amount of heat during operation. To cool these components, hood30also encloses and protects cooling system50. Cooling system50includes at least one heat exchanger, such as radiator52, which is provided to cool internal combustion engine40. Cooling system50may also include, for example, a heat exchanger for cooling the hydraulic system and a heat exchanger for cooling the transmission system. These various heat exchangers may be combined into an assembly. The illustrated cooling system50also includes fan shroud54and fan56at least partially surrounded by fan shroud54. The components of cooling system50may be supported by chassis12or hood30, for example. As shown inFIG. 3, front grill32of hood30is positioned upstream of radiator52; radiator52is positioned upstream of fan shroud54and fan56; and fan shroud54and fan56are positioned upstream of internal combustion engine40.

Referring next toFIGS. 4 and 5, an exemplary fan shroud54is a generally hollow, box-shaped structure. Fan shroud54may be molded or formed from a polymeric material, such as reinforced polypropylene, metal, such as sheet metal, or another suitable material. Fan shroud54includes top wall60, bottom wall62, and side walls64. Top wall60, bottom wall62, and side walls64, of fan shroud54cooperate to define central opening70that extends through fan shroud54.

Referring back toFIGS. 2 and 3, fan56is positioned in central opening70of fan shroud54and is capable of rotating therein. Fan56may be driven by internal combustion engine40, or fan56may be electrically or hydraulically powered, for example. When fan56rotates in central opening70of fan shroud54, air is suctioned into inlet72of fan shroud54and discharged from outlet74of fan shroud54. The location of inlet72and outlet74of fan shroud54may vary depending on the direction of rotation of fan56. According to an exemplary embodiment of the present disclosure, fan56is rotated such that inlet72of fan shroud54faces front grill32of hood30and radiator52, and outlet74of fan shroud54faces internal combustion engine40, as shown inFIG. 3.

In operation, heat transfer fluids absorb heat from various heat-generating vehicle components. The heat transfer fluids then travel through heat exchangers for cooling. For example, hydraulic oil absorbs heat from the hydraulic system of the vehicle and travels through a heat exchanger for cooling. Also, liquid coolant absorbs heat from internal combustion engine40and travels through radiator52for cooling. Fan56rotates in fan shroud54to pull cool, ambient air across these heat exchangers, including radiator52. Specifically, fan56rotates in fan shroud54to pull cool, ambient air into front grill32of hood30, across radiator52, and into inlet72of fan shroud54. According to an exemplary embodiment of the present disclosure, radiator52may be sealed to hood30and to fan shroud54so that essentially all of the incoming air is directed across radiator52and into fan shroud54. The cool, ambient air traveling across radiator52carries heat away from the liquid coolant in radiator52. The cooled liquid coolant leaving radiator52is then recirculated through internal combustion engine40. The heated air carried across radiator52is blown from outlet74of fan shroud54toward internal combustion engine40.

To prevent the heated air carried across the heat exchangers from flowing over internal combustion engine40, hood30of skidder10may be provided with baffle80. As shown inFIGS. 2 and 3, baffle80is located between fan shroud54and internal combustion engine40and divides hood30into a forward, heat exchanger or radiator compartment90and a rear, engine compartment92. Baffle80may be sized and shaped to provide an air barrier between radiator compartment90of hood30and engine compartment92of hood30. For example, baffle80may be sealed to the walls of hood30. In operation, heated air carried across radiator52may be prevented from flowing beyond baffle80and into engine compartment92of hood30. Instead, the heated air may escape from radiator compartment90of hood30via side grill34or other vented portions of hood30, for example.

Although baffle80may prevent heated air from flowing into engine compartment92of hood30, baffle80may also trap heat generated by internal combustion engine40in engine compartment92of hood30. Some heat may escape from engine compartment92of hood30via side grill34′ or other vented portions of hood30, for example.

To further ventilate engine compartment92of hood30, baffle80may include at least one vent aperture82and fan shroud54may include suction aperture84in communication with vent aperture82. According to an exemplary embodiment of the present disclosure, vent aperture82in baffle80is located proximate to suction aperture84in fan shroud54. Vent aperture82and suction aperture84may have an elongate shape or another suitable shape that permits air flow therethrough. For example, an exemplary suction aperture84in fan shroud54may extend substantially the entire length of fan shroud54. Depending on the size of fan shroud54, suction aperture84in fan shroud54may have a length of approximately 20 inches, 30 inches, or more, for example. Suction aperture84in fan shroud54may have a width of approximately 1 inch, 2 inches, or more, for example.

According to an exemplary embodiment of the present disclosure, skidder10includes duct or chamber86extending between baffle80and fan shroud54. Specifically, skidder10includes chamber86extending between vent aperture82in baffle80and suction aperture84in fan shroud54. As shown inFIG. 4, fan shroud54may include duct aperture88, if necessary, to accommodate chamber86.

Referring toFIGS. 3 and 4, suction aperture84is provided in the outer periphery of fan shroud54. For example, suction aperture84may be formed in top wall60, bottom wall62, and/or side walls64of fan shroud54. Similarly, vent aperture82may be formed near a top end, bottom end, or the sides, of baffle80in communication with suction aperture84. In the illustrated embodiment, suction aperture84is formed in top wall60of fan shroud54, and vent aperture82is formed near a top end of baffle80and is located proximate to suction aperture84in top wall60of fan shroud54. Also, suction aperture84in top wall60extends in a direction that is substantially transverse to inlet72and outlet74of fan shroud54. As shown inFIG. 4, suction aperture84, inlet72, and outlet74communicate with central opening70of fan shroud54.

In operation, fan56rotates to pull air into inlet72of fan shroud54. As discussed above, fan56pulls ambient air across radiator52. The airflow across radiator52in radiator compartment90is represented schematically by arrow100inFIG. 6. Additionally, fan56removes air from engine compartment92of hood30by pulling air through vent aperture82in baffle80, through chamber86, and through suction aperture84in fan shroud54. The airflow across internal combustion engine40and through baffle80is represented schematically by arrow102inFIG. 6, and the airflow through suction aperture84in fan shroud54is represented schematically by arrow106inFIG. 4. By positioning vent aperture82near the top of baffle80, hot air that rises in engine compartment92may be removed by fan56. The hot air from radiator52and the hot air from internal combustion engine40are combined in fan shroud54, the two streams entering substantially transversely, or non-parallel, to one another as illustrated schematically inFIG. 6. Then, the combined hot air stream is blown from outlet74of fan shroud54toward baffle80, forcing the air to escape from radiator compartment90of hood30via side grill34or other vented portions of hood30, for example. The exhaust airflow is represented schematically by arrow104inFIG. 6. According to an exemplary embodiment of the present disclosure, the hot air that is pulled from engine compartment92of hood30is replaced by cool, ambient air that enters via side grill34′ or other vented portions of hood30, for example. This cool, ambient air absorbs heat from internal combustion engine40to further cool internal combustion engine40.

The components described above may be designed to optimize cooling of engine compartment92. For example, the size, shape, and position of vent aperture82and suction aperture84may be varied to optimize the flow rate of hot air from engine compartment92. As another example, the rotation speed of fan56may be varied. As yet another example, side grill34of hood30may be designed to optimize the flow of hot air exhausted from radiator compartment90, and side grill34′ of hood30may be designed to optimize the flow of cool, ambient replacement air into engine compartment92.

The present disclosure may lower the temperature inside engine compartment92of hood30to protect internal combustion engine40and other vehicle components located therein. The present disclosure may also lower the surface temperature of skidder10, such as external surfaces of hood30and surfaces of hood30in contact with operator cab22, which may protect the operator and enhance the operator's comfort inside operator cab22. In addition, the present disclosure may improve the performance of an air conditioning system for operator cab22, because the hot air is exhausted from radiator compartment90rather than from engine compartment92located next to operator cab22.

A test assembly was constructed, including a fan and a baffle, similar to fan56and baffle80described above. Two fan shrouds (Fan Shroud A and Fan Shroud B) were also constructed, each having a suction aperture, similar to suction aperture84of fan shroud54described above. The configurations of the suction apertures are described in Table 1 below.

To compare the Fan Shrouds A and B, the fan was rotated at about 1,500 rpm. Less than 8,700 cubic feet per minute (cfm) of air flowed through the fan with Fan Shroud A, while almost 8,900 cfm of air flowed through the fan with Fan Shroud B. However, over 700 cfm of air flowed through the suction aperture of Fan Shroud A, while less than 400 cfm of air flowed through the suction aperture of Fan Shroud B.

Increasing the fan speed to 1,600 rpm increased the airflow through the fan with Fan Shroud B to almost 9,500 cfm, and also increased the airflow through the suction aperture of Fan Shroud B to above 400 cfm.

A computer model was constructed, including a baffle, a fan, and a fan shroud having a suction aperture. The suction aperture was formed in the top wall of the fan shroud and had the same dimensions as that of Fan Shroud A (Table 1). Using computational fluid dynamics (CFD) analysis, and based on a fan speed of 1,500 rpm, the computer calculated over 800 cfm of airflow through the suction aperture.