Cooling fan shroud

A cooling fan shroud comprises multiple, functionally identical sections that form a ring-like structure that completely surrounds the fan when the shroud is installed onto an aperture plate or other structure. The shroud makes the cooling system more efficient by improving air flow at a given fan speed by reducing fan tip clearance, and increasing air flow due through the fan. An alternative, single piece shroud is also provided which can be retrofitted to an existing cooling system.

TECHNICAL FIELD

This disclosure relates generally to a cooling fan shroud for heavy duty vehicles. More particularly, this disclosure relates to a cooling fan shroud for heavy duty vehicles that helps direct air flow through the cooling fan, thereby reducing power requirements, sound emissions and fuel consumption.

BACKGROUND

Heavy duty construction machines such as loaders, tractors, bulldozers, excavators, ground movers and the like generally comprise a machine frame, a work implement mounted to the machine frame and an internal combustion engine to power the work implement. A cooling system may be provided for cooling the engine, the cooling system typically comprising a radiator and a fan enclosed within a housing or cover. The fan may be driven hydraulically, electronically or mechanically via a belt system.

The radiator may be mounted on the machine frame next to the engine. In some machines the cooling fan is located outboard the radiator. The fan pulls cooling air through the radiator for engine cooling purposes, and the air is discharged through the fan grill.

In other machines the fan is located between the radiator and the engine. The fan pushes cooling air through the radiator for engine cooling purposes, and the air is discharged through air exhaust ports typically formed in the cooling system housing.

The fan may be rotatively driven by a hydraulic pump working off the engine, or the fan may be belt driven using a fan belt that works off the engine.

Some cooling fans are located within a circular opening in an aperture plate. Aperture plates are low cost, but they have significant disadvantages in terms of sound emissions, power requirements and fuel consumption. For example, aperture plates have a knife edge that can disrupt the flow of air through the fan.

The present disclosure is directed toward one or more of the problems set forth above.

SUMMARY OF THE DISCLOSURE

In one aspect of the disclosure, a shroud is provided that can be installed around the fan to channel air to and away from the fan. The shroud is mountable to an aperture plate having a circular knife edge defining a circular opening. The shroud comprises two or more functionally identical sections that fit together to form the shroud. Each section comprises an annular body having a convex inner surface and a concave outer surface, a bell shaped downstream section and a bell shaped upstream section extending from either end of a cylindrical duct. The downstream section terminates in a substantially circular downstream end. The upstream section terminates in a substantially circular upstream end. A mounting flange is affixed to the outer surface of each section at the duct and extends radially outward therefrom.

In another aspect, a method of installing a multiple piece shroud in a cooling system is provided. The multiple piece shroud comprises multiple sections, each section comprising a mounting flange. The cooling system comprises a radiator, a housing, an aperture plate mounted to the housing and having a circular knife edge defining a circular opening, a hydraulically driven cooling fan located outboard (away from the engine) of the radiator and mounted to a bracket. The bracket has a top connected to the housing by fasteners. Hydraulic hoses may be operably connected to the fan. A grill may be located outboard the fan and bracket. As part of the method, the grill is removed. The hydraulic hoses, if any, are disconnected from the fan. The fasteners that hold the top of the bracket to the housing or other structure are removed so that the fan and the bracket may be rotated (leaned) outward, away from the radiator, to create workspace. Next, the shroud sections are installed one section at a time. Each shroud section is affixed to the aperture plate with fasteners.

Similarly, in still another aspect of the invention, a method of replacing one or more damaged sections of a multiple piece shroud mounted in a cooling system is provided. The method comprises removing the grill and disconnecting any hydraulic hoses from the fan (if the fan is hydraulically driven). The fasteners that hold the top of the fan bracket to the housing are removed so that the fan and bracket can be leaned outward away from the radiator16to create workspace. The damaged sections can then be removed. Finally, the new shroud sections are installed by affixing each of the one or more new sections to the aperture plate18with fasteners.

In yet another aspect of the disclosure the shroud is a single unitary structure. The single piece shroud is mountable to a mounting structure to reduce fan tip clearance between the mounting structure and a fan. The mounting structure has a circular knife edge defining a circular opening or aperture having an aperture radius. The fan blade tips define a fan tip radius. The shroud comprises an annular, outwardly curved body having a convex, fan-facing surface and a concave outer surface. The fan further comprises a cylindrical duct having two ends and defining a shroud inner radius, a bell shaped downstream section extending from one end of the duct and terminating in a circular downstream end defining a shroud downstream end radius, and a bell shaped upstream section extending from the other end of the duct and terminating in a circular upstream end defining a shroud upstream end radius. The shroud also comprises a mounting flange affixed to the concave surface of the body and extending radially outward therefrom. The mounting flange has an outer perimeter defining a flange outer perimeter radius. In a key aspect of the disclosure there is diametrical clearance between the body upstream end and the knife edge32so that at least one side of the shroud can fit within the aperture plate.

Finally, is still another aspect of the invention, a method of installing a single piece cooling fan shroud on an aperture plate is provided, in which the aperture plate has a knife edge and defines a plurality of spaced apart circumferentially disposed first openings for receiving fasteners. The method comprises the steps of: providing a cooling fan shroud comprising an annular, outwardly curved body having a downstream end, a duct and an upstream end and a flange affixed to the duct and extending radially outward therefrom, the flange having a distal end and a proximal end adjoining the body, the flange defining a plurality of spaced apart circumferentially disposed flange openings for receiving fasteners alignable with the aperture plate openings; positioning the shroud so that the flange openings align with the aperture plate openings; and securing the shroud to the aperture plate with fasteners.

DETAILED DESCRIPTION

While this disclosure may be embodied in many forms, there is shown in the drawings and will herein be described in detail one or more embodiments with the understanding that this disclosure is to be considered an exemplification of the principles of the disclosure and is not intended to limit the disclosure to the illustrated embodiments.

Turning to the drawings, there is shown inFIG. 1an engine cooling system indicated generally at12and comprising a radiator14, a housing16, an aperture plate18and a cooling fan20. The radiator14may be mounted to a machine frame (not shown) or to the housing16at a location adjacent the cooling fan20and may be oriented normal to the axis of rotation (A) of the fan20. The housing16may serve as a structural support for the aperture plate18and may be mounted to the machine frame.

In some cooling systems12like the one shown inFIG. 1, the fan20is located outboard (downstream) of the radiator14on the side away from the engine22and pulls air from the engine compartment23through the radiator14to facilitate the transfer of heat from the coolant circulating within the radiator14to the ambient air. This engine-radiator-fan arrangement is common in bulldozers.

In other cooling systems like the one shown inFIG. 8, the fan20is located downstream of the radiator, between the radiator14and the engine22. The fan20pulls air from the outside through air intake openings25in the housing36and through the radiator14, after which the air exits the engine compartment23through air exhaust openings (not shown).

The fan20generally comprises a hub24and a plurality of spaced apart blades26connected to and radiating outwardly from the hub24. The hub24is mounted to a bracket28or other structure. The bracket28or other structure may be mounted to the cooling system housing16, the aperture plate18, the machine frame or any other suitable structure by fastening means. For example, the bracket28may be mounted on hinges (not shown) located at the bottom of the bracket28and secured to the cooling system housing16by fasteners (not shown) located at the top of the bracket28so that, by removing the fasteners, the fan20and bracket28can be tilted outward for easier access to the radiator14and the aperture plate18.

The aperture plate18is substantially planar and may define a plane (P) normal to the fan axis (A). The aperture plate18may have a circular, inwardly facing perimeter edge32, also known as a “knife edge”, which defines a large circular central opening30. The fan20may be horizontally aligned with the central opening30and may be aligned with or offset from the plane (P). The size of the central opening30is generally a function of the size of the fan20and generally will have a diameter slightly larger than that of the fan20. The distance between the tips (distal edges)34of the fan blades26and the knife edge32is referred to as the fan tip clearance.

For safety, an optional protective grill (not shown) constructed of spaced wire formed into a domed or other configuration may be positioned outboard the fan20and bracket28.

Cooling fans that are hydraulically powered work off of a hydraulic pump powered by the engine. Cooling fans that are belt driven work off of a fan belt that is rotated by an engine drive pulley connected to the crankshaft powered by the engine. Either way, cooling fans are a parasitic load on the engine, and the power drain from the cooling fan can be as much as twenty kilowatts (kW) or more. Increasing air flow by increasing fan speed requires an exponential increase in power drain from the engine and thus fuel consumption, as well as increased noise. Increasing fan speed can also result in increased fan tip erosion. Adding a shroud, as described below, can improve air flow without increasing fan speed, which results in better cooling at lower engine loads and also less fan noise.

FIG. 2is a side cross-sectional view of the engine cooling system ofFIG. 1with the addition of a cooling fan shroud40according to the present disclosure.FIG. 3is a partial close up view ofFIG. 2showing the shroud40in greater detail. According to one embodiment of the present disclosure, the shroud40comprises multiple, functionally identical sections42that form a ring-like structure40that completely surrounds the fan20when the shroud40is installed onto the aperture plate18.

In order to mount the sections42of the shroud40to the aperture plate18, the aperture plate18has spaced apart, circumferentially disposed openings48for receiving bolts or other fasteners50. Each shroud section42has flange openings52spaced apart at the same intervals as the aperture plate openings48so that, when each shroud section42is positioned with its flange46abutting the aperture plate18, the shroud flange openings52and the aperture plate openings48align to receive the fasteners50. There may be some play (extra space) designed into the aperture plate openings48and/or in the flange openings52relative to the opening in the other structure to help position the shroud sections42on the aperture plate18for proper fan tip clearance. If necessary, fastener openings may be drilled through the flange46and/or aperture plate18for mounting purposes.

The shroud40may comprise two, three, four, five or any suitable number of identical sections42, with four being the preferred number because each section42presents a right angle for easy installation. Because the sections are identical, only one part needs to be manufactured, resulting in cost-efficiencies.

FIGS. 4,5and6are various views of a section42of a four piece shroud40. Because the shroud40is substantially circular, each section42describes a ninety degree arc. (In a three section shroud each section describes a one hundred and twenty degree arc; in a two section shroud each section describes a one hundred and eighty degree arc; etc.) Each section42comprises an annular body44and a substantially planar mounting flange46connected to the body44and extending outward therefrom.

As best shown inFIG. 3, the annular body44has a generally C-shaped radial cross-sectional profile, with an optional cylindrical duct62that appears relatively flat in the cross-sectional view ofFIG. 3. The body44is generally outwardly curved (curved away from the fan20) on either side of the duct62, giving the body44a substantially convex, inner (fan-facing) surface54and a substantially concave outer (aperture plate-facing) surface56. The annular body44further comprises a bell shaped downstream section58and a bell shaped upstream section60extending from either side of the duct62. The downstream section58terminates in a substantially circular downstream end64and the upstream section60terminates in a substantially circular upstream end66.

The mounting flange46is affixed to the outer surface56of the duct62and extends radially outward therefrom, forming an annular, ring-like structure. The mounting flange46has an outer edge or perimeter68and an inner end or perimeter70that adjoins the annular body44, preferably along the duct62.

As noted above, the flange46has axially oriented openings52spaced apart at the same intervals as the aperture plate openings48, either as original equipment features or drilled in later. The flange46may be discontinuous, that is, the flange46may have discontinuities or gaps53(FIG. 4) that make it easier to bend or otherwise distort the section42if needed for installation.

The shroud40may be made of metal, plastic, composite material such as fiberglass, or any suitable material. The multiple sections42are partially nestable so the shroud40can be shipped in a smaller space than a single piece shroud.

The amount and quality of airflow through the fan20is a function of, among other things, fan speed, fan projection (i.e., location of the fan20with respect to the shroud40), and the shape of the shroud40. Therefore the upstream section60of the shroud40may be optimized to guide or channel the flow of air into the fan40, while the downstream section58of the shroud40may be designed to maximize air flow by transitioning the exiting air from axial to radial flow.

Although the multiple piece cooling fan shroud40is shown inFIG. 2as part of a cooling system12in which the fan20is located outboard of the radiator14, it should be understood that the shroud40also may be used as part of a cooling system in which the fan20is located between the radiator14and the engine22like that shown inFIG. 8.

The shroud40can be installed as original equipment. The shroud40can also be added to a cooling system12like that shown inFIG. 1as part of a retrofitting. Finally, damaged sections42of a multiple-piece shroud40can be replaced in the field.

The installation of a new shroud40as part of a cooling system retrofitting will now be described with respect to the cooling system12ofFIG. 1. As previously noted, the cooling system12comprises a radiator14, a housing16, an aperture plate18, a cooling fan20, a bracket28and a grill (not shown). The bracket28has a top connected to the housing16by fasteners (not shown). The housing16serves as a structural support for the aperture plate18. The fan20is located outboard (downstream) of the radiator14and is mounted to the bracket28. The aperture plate18has a circular knife edge32defining a circular opening30.

The shroud40may be installed from the front (downstream) side of such a cooling system12by removing the protective grill (not shown inFIG. 1), unhooking some of the hydraulic hoses if the fan is hydraulically driven (also not shown inFIG. 1), undoing some of the bolts that hold the bracket28in place (not shown), leaning the fan20and bracket28outward to create workspace, and installing the shroud sections42, one section42at a time. The shroud sections42are affixed to the aperture plate18and may also be affixed to each other. If the fastener openings in the shroud sections42and the aperture plate18do not align, it may be necessary to drill new openings in one or the other to accommodate the fasteners50.

If one or more shroud sections42become broken or damaged, the sections42also can be replaced from the front (downstream) side of the cooling system12(outboard the fan20) in a similar manner. That is, by removing the protective grill, unhooking some of the hydraulic hoses, undoing some of the bolts that hold the bracket28in place, leaning the fan20and bracket28outward to create workspace, removing the damaged section(s)42and installing new section(s)42.

FIGS. 7-9show another aspect of the disclosure, a single piece shroud80. Like the multiple piece shroud40, the single piece shroud80is substantially circular and comprises an annular body84and a substantially planar mounting flange86connected to the body84. In contrast to the multiple piece shroud40, the single piece shroud80may be formed of roll bent aluminum with two ends that are connected to form a single, circular structure. Manufacturing single piece, extruded aluminum shrouds of varying diameters can be accomplished using a single extrusion die by extruding aluminum pieces of different lengths. After extrusion, the aluminum piece is simply bent to the desired diameter.

The single piece shroud80may be installed as original equipment. In some cases, despite being a single piece, the shroud80also may be installed in the field without removing the fan20and without bending or otherwise distorting the shroud16due to its unique geometry, as explained below.

Like the multiple piece shroud40, the single piece shroud80may be used in any suitable cooling system, including the cooling system shown inFIG. 1in which the cooling fan20is located on the side of the radiator14away from the engine22, as well as the cooling system shown inFIG. 8in which the fan20is located between the radiator14and the engine22. In the latter case, the shroud80may still be installed in the field without too much difficulty, as explained below.

As best shown inFIGS. 9A and 9B, the annular body84has a generally C-shaped axial cross-sectional profile. The body84is outwardly curved (curved away from the fan20) and has a substantially convex, inner (fan-facing) surface94and a substantially concave outer surface96. The annular body84further comprises a bell shaped downstream section98and a bell shaped upstream section100extending from either end of an optional, cylindrical duct102. The downstream section98terminates in a substantially circular downstream end104and the upstream section100terminates in a substantially circular upstream end106.

As in the previous, multiple piece, embodiment, the mounting flange86may be affixed to and extend radially outward from the outer surface96of the duct102. The mounting flange86has an outer edge or perimeter108and an inner end or perimeter110adjoining the annular body84. The shroud80and, more particularly, the flange86, are affixed to the aperture plate18by fasteners50such as bolts. Both the flange86and aperture plate18have openings that align when the shroud80is installed for receiving fasteners50there through. The openings may be formed as original equipment features in the shroud80and/or aperture plate18or drilled later on as needed.

In the discussion that follows various terms are used that will now be defined:Fan tip radius (R1): the distance of the fan blade tips34from the fan axis (A).Shroud inner radius (R2): the radial distance defined by the shroud duct102; also, the inner radius of the shroud. If the shroud80is positioned concentrically around the fan20as shown inFIG. 9B, then R2 is the distance from the shroud duct102to the fan axis (A).Shroud upstream end radius (R3): the radial distance defined by the shroud upstream end106. If the shroud80is positioned concentrically around the fan20as shown inFIG. 9B, then R3 is the distance from the shroud upstream end106to the fan axis (A).Shroud downstream end radius (R4): the radial distance defined by the shroud downstream end106. If the shroud80is positioned concentrically around the fan20as shown inFIG. 9B, then R4 is the distance from the shroud downstream end104to the fan axis (A).Aperture radius (R5): the radial distance defined by the opening30in the aperture plate18. If the fan20is positioned concentrically with respect to the aperture plate18as shown inFIG. 9B, then R5 is the distance from the aperture plate knife edge32to the fan axis (A).Flange outer perimeter radius (R6): the radial distance defined by the flange outer perimeter108. If the shroud80is positioned concentrically around the fan20as shown inFIG. 9B, then R6 is the distance from the flange outer perimeter108to the fan axis (A).Self-locating ring outer radius (R7): the radial distance defined by the outer surface of the self-locating ring116. If the shroud80is positioned concentrically around the fan20as shown inFIG. 10, then R7 is the distance from outer surface of the self-locating ring116to the fan axis (A).

In cooling systems like that shown inFIGS. 8 and 9in which the aperture plate18and fan20are located between the engine and the radiator, and thus the radiator14is upstream of the fan20, installing the shroud80from the engine (downstream) side112of the aperture plate18has advantages over installing the shroud80from the radiator (upstream) side114. Installing the shroud80from the radiator side can require pulling out the radiator14, which takes a significant amount of time. Installing the shroud80from the engine side typically requires removing only a couple of hoses and the fan bracket.

Despite being a single piece, the shroud80may be installed onto an aperture plate18from the engine side without removing the fan20and without significant bending or other distorting of the shroud80. This can be accomplished if there is sufficient clearance between the fan20and the aperture plate18. That is, the single piece shroud80may be installed without removing the fan20if at least one side of the shroud80fits between the fan20and the aperture plate18(or other structure within which the fan20is located, i.e., transversely aligned). Put another way, the tip clearance between the fan blades26and the aperture plate18must be sufficiently large to allow the shroud80to be inserted between the fan20and the aperture plate18.

For example, and referring toFIGS. 9A and 9B, the single piece shroud80may be installed onto the engine side of the aperture plate18without removing the fan20if the shroud upstream end100fits between the fan20and the aperture plate18. More particularly, the shroud inner radius R2 must be greater than the fan tip radius R1 so that the shroud clears the fan blades26, and the shroud upstream end radius R3 must be less than the aperture radius R4 so that the shroud80fits within the aperture plate18.

At the same time, the shroud flange86must extend radially outward far enough so that the flange86can be affixed to the aperture plate18or other mounting structure. This requires that the flange outer perimeter radius R6 be sufficiently larger than the aperture radius R5 to enable the flange86to be mounted to the aperture plate18with fastening means50.

In a retrofitting situation where the shroud80is being installed in the field, the diameter of the fan20may be too big to allow the installation of a shroud. (The tip clearance may be too small.) If this is the case, then the old fan can be replaced with a smaller diameter fan to allow room for the shroud80. If necessary, openings can be drilled into the aperture plate18and/or shroud80to accommodate the fasteners50that secure the shroud80to the aperture plate18.

FIG. 10illustrates a further embodiment of the disclosure in which the shroud80further comprises an annular self-locating ring116extending axially from at least one side of the flange86. Preferably the self-locating ring116is circular, extends axially from the radiator (upstream) side of the flange86, and has an outer surface118that defines a self-locating ring outer radius R7 substantially equal to or slightly less than the aperture radius R5. In other words, the locating ring outer surface118and the knife edge inner surface32should have substantially the same circumference so that the shroud80fits within the aperture plate18with little or no play (movement). The self-locating ring116helps center the shroud80within the opening30, allowing the operator to align the openings—or drill new openings in the aperture plate18and/or shroud80—for receiving fasteners50.

In still another aspect of the disclosure a method of installing a single piece cooling fan shroud80on an aperture plate18or other structure is provided. The aperture plate18has a free edge knife edge32and a plurality of spaced apart, circumferentially disposed fastener openings48for receiving bolts or other fasteners50, The method comprises the steps of:providing a cooling fan shroud80comprising an annular, outwardly curved body84having a downstream section98and an upstream section100; and a mounting flange86affixed to the body84and extending radially outward therefrom, the mounting flange86having a free outer perimeter108and a inner perimeter110adjoining the body84, the flange86defining a plurality of spaced apart circumferentially disposed flange openings92for receiving fasteners50, the flange openings92being alignable with the aperture plate openings48;positioning the shroud80so that the flange openings92align with the aperture plate openings48; andsecuring the shroud80to the aperture plate18with fasteners50.

The method may include the steps of positioning the shroud80within the aperture plate18, either with or without the aid of a self-locating ring116, and drilling openings through the flange86and/or the aperture plate18for receiving the fasteners50.

INDUSTRIAL APPLICABILITY

The multiple piece embodiment described herein is intended for use as original equipment in bulldozers and similar machines, where the cooling fan typically is located outboard of the radiator away from the engine. However, it should be understood that the multiple piece embodiment may be used in other situations, such as retrofitting a cooling system, and with any suitable cooling system, including a cooling system in which the fan is located between the radiator and the engine.

The multiple piece shroud was designed specifically for tractor machines manufactured by Caterpillar Inc. meeting U.S. Environmental Protection Agency (EPA) Tier 4 diesel emissions regulations, but could be used in other machines as well. Various shrouds can be designed for specific machines.

The single piece embodiment described herein is intended for use either as original equipment or for retrofitting in the field in heavy duty machines, including but not limited to machines in which the fan is located between the engine and the radiator.

All of the described shroud embodiments are intended to make the cooling system more efficient by improving air flow at a given fan speed by reducing fan tip clearance and increasing air flow due through the fan.

It is understood that the embodiments of the disclosure described above are only particular examples which serve to illustrate the principles of the disclosure. Modifications and alternative embodiments of the disclosure are contemplated which do not depart from the scope of the disclosure as defined by the foregoing teachings and appended claims. It is intended that the claims cover all such modifications and alternative embodiments that fall within their scope.