Patent Application
20140106659
The present disclosure relates generally to air cooling systems. Specifically, an embodiment of the present invention relates to air cooling system for a compartment.
Work machines, for example wheel loaders, generally require relatively high power levels to perform desired work on a worksite. To achieve these high power levels, engines in the machines often operate at relatively high engine and exhaust system temperatures. Engine exhaust aftertreatment equipment, to meet stricter emissions regulation compliance, often reduces the available space. Thus, airflow essential in cooling is reduced. Most of these machines are also subject to noise regulations in many regions of the world. Enclosing the engine in a compartment, reducing openings to the compartment, and adding larger mufflers are methods that have been used to meet these acoustic emission requirements. The combination of increased engine and exhaust temperatures, placing the engine in an enclosed compartment with fewer openings, and reducing the airflow in the compartment present substantial cooling challenges.
The paper “A High Performance, Low Back Pressure Jet Ejector” presented by John F. Foss (Mechanical Engineering Department, Michigan State University, East Lansing, Mich., USA) and Alan R. Lawrenz (Mechanical Engineering Department, Michigan State University, East Lansing, Mich., USA) at the proceedings of the 2011 ASME-JSME-KSME Joint Fluids Engineering Conference held Jul. 24-29, 2011 in Hamamatsu, Shizuoka, Japan, proposes enhanced mixing, with the attendant transfer of momentum between a high speed jet and its surrounding fluid, can be created by the use of triangularly-shaped tabs in conjunction with a tapered exhaust stack. The basic physics of the primary tab flow is to create a “pressure hill” on the bounding surface of the primary conduit. Since vorticity is introduced into a flow at a physical surface in the presence of a surface pressure gradient (as if the entering vorticity is “rolling down the hill”), there are streamwise vortex motions at the exit plane that propel the primary flow into the ambient region. A secondary added tab provides an attachment surface that helps the vortex motions advance into the ambient region for increased entrainment.
In one aspect of the disclosure, a compartment cooling system includes a housing defining a substantially enclosed compartment, a flow of heated gas, a nozzle, and multiple tabs. The housing has an air inlet and an air outlet stack defining a flow path. The nozzle directs the flow of heated gas substantially in the flow path direction. The nozzle has an outlet end with a predefined shape. The multiple tabs are adjacent to and spaced about the outlet end. Each tab has a side adjacent the outlet end, and at least three sides in the flow of heated gas. The sides in the flow of heated gas form at least two corners.
In another aspect of the disclosure, an engine compartment cooling system includes a housing defining a substantially enclosed compartment, an engine disposed in the compartment, an engine exhaust system, and multiple tabs. The housing includes an air inlet and an air outlet stack defining a flow path direction. The engine exhausts a flow of heated gas. The engine exhaust system includes a nozzle for directing the flow of heated gas substantially in the flow path direction. The nozzle has an outlet end with a predefined shape. Each tab has a side adjacent the outlet end, and at least three sides in the flow of heated gas. The sides in the flow of heated gas form at least two corners.
In another aspect of the disclosure, a machine compartment cooling system includes a machine body substantially defining an enclosed compartment, an engine disposed in the compartment, an engine exhaust system, and multiple tabs. The machine body includes a compartment air inlet and a compartment air outlet stack defining a flow path direction. The engine powers the machine and exhausts a flow of heated gas. The engine exhaust system includes a nozzle for directing the flow of heated gas substantially in the flow path direction. The nozzle has an outlet end with a predefined shape. Each tab has a side adjacent the outlet end, and at least three sides in the flow of heated gas. The sides in the flow of heated gas form at least two corners.
In another aspect of the disclosure, a method of cooling a compartment is disclosed. A housing substantially encloses and defines the compartment. The housing includes an air inlet and an air outlet stack defining a flow path. The compartment substantially encloses a heat radiating component. The method includes directing a flow of heated gas into the compartment substantially in the flow path direction through a nozzle with an outlet end having a predefined shape; directing the flow of heated gas over at least three sides and at least two corners formed by the three sides of each of multiple tabs, the tabs adjacent to and spaced about the outlet end; drawing air cooler than the flow of heated gas into the compartment through the air inlet; transferring heat radiating from the heat radiating component to the cooler air; and creating vortex flow between the heated gas and the cooler air with the tabs to draw the cooler air through the compartment and out of the compartment through the air outlet stack.
(Note: In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and irregular motions, which may include many eddies of different scales. A vortex (plural: vortices) means a spinning or swirling flow of fluid. Although vortex can create turbulence, people typically consider vortex as large scale and identifiable swirling flow).
Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Generally, corresponding reference numbers will be used throughout the drawings to refer to the same or corresponding parts.
Referring now to
The wheel loader 104 is equipped with systems that facilitate the operation of the wheel loader 104 at a worksite. In the illustrated embodiment, these systems include a work implement system 109, a drive system 108, and a power system 106 that provides power to the work implement system 109 and the drive system 106. The drive system 108 propels the wheel loader 104 on ground engaging devices 111 (depicted as wheels) to move the wheel loader 104 from one location to another. The work implement system 109 includes at least one work implement 168 (depicted as a bucket) and actuators 170 (depicted as a hydraulic cylinder assemblies) to move the work implement 168 to perform work at the worksite. The power system 106 includes an engine 116. The engine 116 may include an internal combustion reciprocating engine, a turbine, a combination engine/generator, a fuel cell or any other engine known in the art. The wheel loader 104 includes a body 172 and a cab 174 providing a place for an operator to control the wheel loader 104 from. The body 172 defines a substantially enclosed compartment 114, a compartment gas inlet 123 and a gas outlet 125. Wheel loader 104 includes an embodiment of a cooling system 110, depicted in
Referring now to
The illustrated embodiment includes an engine 116 disposed in the compartment 114 and exhausting a flow of a first gas 128 through the nozzle 122. The flow of the first gas may include a flow of heated gas. Although engine 116 exhausts the flow of the first gas 128 in the illustrated embodiment, in other embodiments the flow of the first gas 128 may originate and be directed through the nozzle 122 by other devices or processes known in the art. For example, a turbine may exhaust the flow of the first gas 128 into the nozzle 122, or a manufacturing process may create heat and a series of fans, air conduits, and/or valves may direct the flow of the first gas 128 through the nozzle 122.
Although engine 116 is depicted disposed in the compartment 114, in other embodiments, engine 116 may be located outside the compartment 114. In an embodiment where engine 116 includes an internal combustion engine, the flow of the first gas includes a stream of exhaust from the engine 116. In the embodiment illustrated, the engine 116 includes an air intake 120 fluidly connecting the engine 116 to air outside the compartment 114. The air intake 120 includes an air cleaner 176.
In the illustrated embodiment, the engine 116 includes an exhaust outlet 121. An exhaust system 117 is fluidly connected to the exhaust outlet 121. The exhaust system 117 includes aftertreatment 118, and a muffler 119. The nozzle 122 is fluidly connected to the exhaust outlet 121 to flow exhaust gas substantially in the flow path 126 direction. In the embodiment depicted, exhaust gas flows from the exhaust outlet 121, through the exhaust system 117, through the nozzle 122, and into the compartment 114 through the nozzle outlet 130. Some embodiments may not include the aftertreatment 118 and/or the muffler 119.
When engine 116 is running, engine 116, aftertreatment 118, and muffler 119 may transfer heat into the compartment 114 through convection as shown by the arrows marked “H”. In other embodiments, the compartment 114 may enclose other components. Exemplary non-limiting components include hydraulic pumps, transmissions, gear boxes, and hydraulic valves. Some, none, or all, of these other components may also transfer heat into the compartment 114 through convection.
Gas inlet 123 and gas outlet 125 fluidly connect the compartment 114 with gas outside the compartment 114. Gas outlet 125 defines a flow path 126 for gases to flow out of compartment 114. A second gas may enter compartment 114 through air inlet 123, flow through the compartment 114, and flow out of the compartment 114 through exhaust stack 124 via flow path 126. Arrows labeled 166 depict a flow of the second gas into and through the compartment 114. In some embodiments, the second gas includes ambient temperature air from outside the compartment 114. In most circumstances, the second gas will be cooler than the first gas. Heat may be transferred by convection from the engine 116, aftertreatment 118, and/or other components disposed in the compartment 114 to the second gas and be dispersed outside the compartment 114 as gases flow out exhaust stack 124.
Referring now to
The nozzle 122 includes a nozzle body 142 having a nozzle side wall 144. In the illustrated embodiment, the nozzle body 142 is substantially cylindrical. In alternative embodiments, the body 142 may be any elongated tube type shape known in the art to be operable to direct the flow of heated gas 128 in the flow path 126 direction. Non-limiting examples include a tube like structure with cross sections in the shapes of ellipses or polygons such as octagons, or rectangles. In some embodiments, the body 142 may include cross sections which differ in shape and size at different points on the body 142. The body 142 may, for example, include a venturi type shape. At least a portion of the side wall 144 interfaces with the air in compartment 114 near the outlet end 130.
Multiple tabs 132 are adjacent to and spaced around the outlet end 130. In the illustrated embodiment, the tabs 132 are circumferentially spaced around the circular outlet end 130. Each tab 132 includes an adjacent side 134 adjacent the outlet end 130 of the nozzle 120, and at least three gas flow sides 136 in the flow of heated gas. The gas flow sides 136 form at least two corners 140.
In the illustrated embodiment four tabs 132 are circumferentially evenly spaced around the outlet end 130. In alternative embodiments, different numbers of tabs 132 may be evenly, or unevenly, spaced around the predefined shape of the outlet end 130. There may be, for example, as few as two tabs 132, or as many as eight tabs 132. The number of tabs 132, the shape of tabs 132, and the size of tabs 132, may be determined as a function of a number of factors. Non-limiting examples of factors to be considered include estimates of the range of velocities and temperatures of the stream of the first gas, the velocity profile of the stream of the first gas, and the range of other characteristics of the stream of the first gas. Other examples may include the size and shape of the nozzle 122 and outlet end 130, any obstacle or blockages along the path of the stream of the first gas, the size of the compartment 114, the range of the amount of heat to be convected from components in the compartment 114, the size, placement, and shape of the air inlet 123, and the size and configuration of the exhaust stack 124.
In the illustrated embodiment, the tabs 132 are fixedly attached to the nozzle 122 such that the adjacent side 134 is adjacent the outlet end 130. The tabs 132 may, for example, be welded onto the body 142 of the nozzle 122 with tab attachment pieces 152 as shown and explained in relation to
It is also contemplated that in some embodiments, the tabs 132 may be fixedly attached to another component(s) different than the nozzle 122, and held stationary against the nozzle 122, such that the adjacent sides 134 are adjacent the outlet end 130. In other embodiments the tabs 132 may be fixedly attached to another component(s) different than the nozzle 122, and held in the first gas flow path. For example, the aftertreatment 118, muffler 119, and/or nozzle 122 may be at least partially enclosed by a housing (not shown). The tabs 132 may be fixedly attached to the housing by, for example, brackets, such that the adjacent sides 134 are adjacent the outlet end 130, and/or in the first gas flow.
In the embodiment illustrated, each tab 132 is a generally a trapezoidal shape with a semi-circular adjacent side 134, and three gas flow sides 136 which include an end 146 and two sides 148 of the trapezoidal shape. As depicted in
Tabs 132 may include a compartment surface 147 and a first gas flow surface 145. In the illustrated embodiment, each tab 132 is substantially flat, and the adjacent side 134 and gas flow sides 136 form the outline of the compartment surface 147 and the gas flow surface 145. Both the compartment surface 147 and a first gas flow surface 145 are generally planar. The compartment surface 147 may be in contact with compartment 114 air, and the gas flow surface 145 may be in contact with the flow of the first gas from the nozzle 122. In alternative embodiments, the tabs 132 may be curved as opposed to flat, and in some embodiments the tabs 132 may be angled outward in relation to the nozzle outlet 130.
In the embodiment illustrated, each tab 132 is generally the same size and shape, and adjacent the outlet end 130 at the same tab-compartment air flow angle (α). In alternative embodiments, the tabs 132 may be different shapes and sizes, and adjacent the outlet end 130 at different tab-compartment air flow angles (α).
Referring now to
The tab assembly 150 may be fixedly attached to the nozzle 122 by fixedly attaching the nozzle side 156 of the tab attachment piece 152 to the nozzle side wall 144 of the nozzle 122 such that the adjacent side 134 of the tab 132 is adjacent the outlet end 130 of the nozzle 122. The nozzle side 156 may be fixedly attached to the nozzle side wall 144 through welding, adhesive, clamps, snap rings, bolts, or any other means known in the art.
When machine 100 is required to perform work requiring high power levels, and meet stricter exhaust emission regulations, engine 116, aftertreatment 118, and muffler 119 may operate with relatively high engine and exhaust temperatures. Engine 116, aftertreatment 118, and/or muffler 119 may also be substantially enclosed in compartment 114 to assist in meeting noise emission regulations. The second gas flow 166 necessary to effectively cool the engine 116 and/or other components in these conditions may be difficult to achieve. Directing the flow of the first gas into the compartment 114 substantially in the direction of the flow path 126, may create a pumping action which draws and increases the velocity of the flow of the cooler second gas 166 through the air inlet 123, through the compartment 114, and out the exhaust stack 124. Directing the flow of the first gas 128 through nozzle 122, and over at least three gas flow sides 136 and at least two corners 140 formed by the three gas flow sides 136 on multiple tabs 132 adjacent to and spaced about the outlet end 130 of the nozzle 122, may increase the pumping effect and the flow of the cooler second gas 166 through the compartment 114. When the flow of the first gas 128 meets the flow of the second gas at these corners, vortices may form. These vortices may increase the velocity of the flow of the second gas through the compartment 114, and thus improve cooling efficiency. Experimental results indicate, that in many circumstances, increasing the number of corners 140 on tabs 132 increases the velocity of the flow of the second gas through the compartment 114, generating a higher volume flow of the second gas through the compartment 114, and providing better cooling of components such as the engine 116, aftertreatment, 118, and muffler 119 contained in the compartment 114.
Referring now to
The method 200 includes directing a flow of a first gas 128 into the compartment 114 substantially in the flow path 126 direction; and directing the flow of the first gas 128 over at least three sides 136 and at least two corners 140 formed by the three sides 136 of each of multiple tabs 132. Additionally included in the method 200 is drawing a second gas, cooler than the first gas, through the gas inlet 123, into and through the compartment 114, and out the gas outlet 125; and cooling the component through convection with the second gas. The method also includes creating vortices between the flow of the first gas 128 and the cooler second gas with the tabs 132 to increase the velocity of the second gas through the compartment 114 and increase the rate of convection.
The method 200 starts at step 202 and proceeds to step 204. Step 204 includes directing a flow of heated gas 128 into the compartment 114 substantially in the flow path 126 direction. In the embodiment illustrated in relation to
The method 200 proceeds from step 204 to step 206. Step 206 includes directing the flow of heated gas 128 over at least three gas flow sides 136 and at least two corners 140 formed by the gas flow sides 136 of each of multiple tabs 132. In the embodiment depicted in
A tab 132 may include a gas flow surface 145 and a compartment surface 147. The gas flow surface 145 may face into the flow of the first gas 128. In the embodiment depicted in
The method 200 proceeds from step 206 to step 208. Step 208 includes drawing a second gas, cooler than the first gas, through the gas inlet 123, into and through the compartment 114, and out the gas outlet 125. Air inlet 123 may include an aperture in the housing such as, for example, a vent. In some embodiments the second gas may flow through a tube, or other ductwork, to the air inlet 123. In the depicted embodiment of the machine 100, where the machine body 172 defines the compartment 114, the air inlet may be an aperture at the bottom of the compartment 114. In most circumstances, the air outside the compartment 114 and/or surrounding the machine 100 will be cooler than the flow of the first gas 128 being exhausted by engine 116. The temperature differential between the exhaust gas and the ambient air entering the compartment 114 will generally increase as engine 116 operating temperature and/or load increases.
The method 200 proceeds from step 208 to step 210. Step 210 includes cooling the component through convection with the second gas. The component may include the engine 116, aftertreatment 118, muffler 119, and/or other components (not shown) such as transmissions, hydraulic valves and pumps, and other components which would be known to an ordinary person skilled in the art now or in the future. Transferring heat from components to a flow of a second gas 166 by convection is a well known cooling method in the art.
The method 200 proceeds from step 210 to 212. Step 212 includes creating vortex flow between the flow of the first gas 128 and the cooler second gas with the tabs 132 to increase the velocity of the second gas through the compartment 114 and increase the rate of convection. Increasing the velocity of a cooler second gas into a compartment 114, through the compartment 114, and out an exhaust stack 124, by directing a flow of a first gas 128 into the compartment 114, substantially in the direction of a flow path 126 defined by the exhaust stack 124, is well known in the art. In the depicted embodiment of
Referring now to
From the foregoing it will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications or variations may be made without deviating from the spirit or scope of inventive features claimed herein. Other embodiments will be apparent to those skilled in the art from consideration of the specification and figures and practice of the arrangements disclosed herein. It is intended that the specification and disclosed examples be considered as exemplary only, with a true inventive scope and spirit being indicated by the following claims and their equivalents.
