CA1040035A - Recirculation barrier for a heat transfer system - Google Patents
Recirculation barrier for a heat transfer systemInfo
- Publication number
- CA1040035A CA1040035A CA290,975A CA290975A CA1040035A CA 1040035 A CA1040035 A CA 1040035A CA 290975 A CA290975 A CA 290975A CA 1040035 A CA1040035 A CA 1040035A
- Authority
- CA
- Canada
- Prior art keywords
- fan
- plane
- radial
- heat exchange
- shroud
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
- F01P5/00—Pumping cooling-air or liquid coolants
- F01P5/02—Pumping cooling-air; Arrangements of cooling-air pumps, e.g. fans or blowers
- F01P5/06—Guiding or ducting air to, or from, ducted fans
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D19/00—Axial-flow pumps
- F04D19/002—Axial flow fans
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/52—Casings; Connections of working fluid for axial pumps
- F04D29/54—Fluid-guiding means, e.g. diffusers
- F04D29/541—Specially adapted for elastic fluid pumps
- F04D29/545—Ducts
- F04D29/547—Ducts having a special shape in order to influence fluid flow
Abstract
RECIRCULATION BARRIER FOR
A HEAT TRANSFER SYSTEM
ABSTRACT OF THE DISCLOSURE
An internal combustion engine, having a heat exchange cooling system, a fan for moving air therethrough and a fan shroud and shroud exit section for controlling the air path. The shroud exit encloses the fan and in-cludes throat (CF) radial expander (R) and radial flat (RF) sections whereby air is drawn through the heat exchanger axially and expelled radially along said exit sections. The fan has a projected axial width (AW) such that a general relationship exists with the shroud exit sections: CF = AW/3, RF = AW/3, and R = 2AW/3. A barrier located behind the fan and away from the heat exchanger eliminates air recirculation in the fan hub region.
A HEAT TRANSFER SYSTEM
ABSTRACT OF THE DISCLOSURE
An internal combustion engine, having a heat exchange cooling system, a fan for moving air therethrough and a fan shroud and shroud exit section for controlling the air path. The shroud exit encloses the fan and in-cludes throat (CF) radial expander (R) and radial flat (RF) sections whereby air is drawn through the heat exchanger axially and expelled radially along said exit sections. The fan has a projected axial width (AW) such that a general relationship exists with the shroud exit sections: CF = AW/3, RF = AW/3, and R = 2AW/3. A barrier located behind the fan and away from the heat exchanger eliminates air recirculation in the fan hub region.
Description
This application i~a4~1el~sSon of Canadian Serial No. 213,118, filed November 6, 1974.
RECIRCULATION BARRIER FOR A HEAT TRANSFER SYSTEM
SPECIFIC~,TION
This invention relates to a cooling assembly and more ; particularly to a fan shroud, a contoured fan shroud exit section and a fan loca-ted therein which has an air obs-truction barrier therebehind. Reference should be made -to my copending Canadian applications Serial Numbers 184,3~0 and 184,381, both filed November 2, 1973.
Most vehicles in general used today are driven by internal combustion engines. These engines being heat produc-ing are for the most part water cooled, that is, the engine is jacketed for circulation of water which takes up the heat and subsequently transfers it to the atmosphere. The radiator is used for cooling the liquid circulating through the engine by dissipating the heat to an air stream. The air flowing through the radiator absorbs the heat and carries it out into the atmosphere. Different types of fan systems are used to achieve the necessary air velocity through the radiator.
That is, some fan assemblies draw air from the atmosphere through the radiator and back over the engine thereafter exiting to the atmosphere. This type of fan is known as an axial flow suction fan, drawing air axially through the radi-ator and discharging it into the engine compartment. Other fans work in the reversed manner, that is, they draw air from the engine compartment wherefrom it is blown forwardly through the radiator to achieve the necessary radiator cooling.
Under optimum conditions it is believed prior art fans norMally employ only about 1/3 of the length of the fan blade for the movement of air through the heat exchanger. The outer 1/3 of the blade length or tip regions, pulls in air from behind the shroud and recirculates it. The inner 1/3 or, hub region, pulls in air from the rear which it thereafter dis-
RECIRCULATION BARRIER FOR A HEAT TRANSFER SYSTEM
SPECIFIC~,TION
This invention relates to a cooling assembly and more ; particularly to a fan shroud, a contoured fan shroud exit section and a fan loca-ted therein which has an air obs-truction barrier therebehind. Reference should be made -to my copending Canadian applications Serial Numbers 184,3~0 and 184,381, both filed November 2, 1973.
Most vehicles in general used today are driven by internal combustion engines. These engines being heat produc-ing are for the most part water cooled, that is, the engine is jacketed for circulation of water which takes up the heat and subsequently transfers it to the atmosphere. The radiator is used for cooling the liquid circulating through the engine by dissipating the heat to an air stream. The air flowing through the radiator absorbs the heat and carries it out into the atmosphere. Different types of fan systems are used to achieve the necessary air velocity through the radiator.
That is, some fan assemblies draw air from the atmosphere through the radiator and back over the engine thereafter exiting to the atmosphere. This type of fan is known as an axial flow suction fan, drawing air axially through the radi-ator and discharging it into the engine compartment. Other fans work in the reversed manner, that is, they draw air from the engine compartment wherefrom it is blown forwardly through the radiator to achieve the necessary radiator cooling.
Under optimum conditions it is believed prior art fans norMally employ only about 1/3 of the length of the fan blade for the movement of air through the heat exchanger. The outer 1/3 of the blade length or tip regions, pulls in air from behind the shroud and recirculates it. The inner 1/3 or, hub region, pulls in air from the rear which it thereafter dis-
-2-~IL(J4Q03S
charges rearwardly. As a result of these conditions only about the middle 1/3 of the fan blade is effective in moving a cooling stream of air past the heat exchanger.
It has been shown, see copending Canadian application Serial Number 184,880, that a contoured shroud exit reduces horsepower requirements and generated noise and hampers the recirculation of air in the tip regions of the fan blade because of the radial air discharge pattern generated thereby.
Employment of Ihe contoured shroud exit thus increases the amount of the fan blade which is effective for moving air past the heat exchanger means.
It is therefore an object of this invention to provide an air barrier means to prevent the drawing in and recirculat-ion of air from behind the fan blade. Still another object of this invention is to provide an air barrier means which does not interere with the flow of air in the tip regions of the fan blade. ~et another object of this invention is to provide an air barrier means which functions as a safety guard. Another object of this invention is to provide a 2~ cooling assembly wherein a majority of the length of fan blade is functioning to move air each past the heat exchanger.
The invention thus contemplates a heat exchange apparatus which comprises a heat exchange means having front and rear faces, a shroud means including a forward section having forwardmost edge means arranged to encircle the rear face of the heat exchange means, and a rear exit shroud means having forwardmost edge means joined to rearwardmost edge means of the forward section. The exit shroud means includes, in successive sections, a generally cylindrical, axially extending throat section, an annular, radial curved section, and an annular, generally radially extending flat portion- A rotatable axial flow, suction-type fan encircled by the rear exit shroud means has a plurality of circumferentially spaced impeller blades (J3S
extending radially from a hub with each of the impeller blades having an effective axial width (AW) measured axially along the rotational axis of the fan between a first plane and a second plane. Those planes are axially spaced and parallel with respect to each other and disposed substantially normal to the rotational axis of the fan with the first and second planes extending radial-ly, respectively, through-points on the leading edges of the ;
impeller blades at the radial tip regions thereof and through points on the trailing edges of the impeller blades at the radial r lO- tip portions thereof. The second plane is substantially coincid-ent with the plane containing the annular, generally radially extending flat portion of the exit shroud means, and the following relationships exist: RF = AW/3 plus or minus 12 percent of AW, CF = AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW where RF is the radial length of the radially extending flat portion, CF is the axial length of the cylindrical throat section, and R is the radius of curvature of the radial curved section.
An air recirculation barrier means is axially spaced rearwardly of the second plane a predetermined distance less than one half of the diameter of the fan for obstructing axial flow of air in a forward direction from the region axially rearwardly of the fan hub when the fan is rotated.
In accordance with the preferred embodiment of this inven-tion a vehicle is provided having a liquid cooled internal com- ,~
bustion engine and a radiator cooling system for dissipating the heat produced. The radiator cooling system includes a standard r radiator, an axial flow fan facing the radiator and having a plurality of angular blades whereby air is drawn rearwardly through the radiator. A shroud rearwardly extends from the back face of the radiator to channel air through the radiator and hamper the fan from drawing air which has not passed through or at least come in contact with the perforated heat exchanging ~L040~35 surfaces of the radiator. For the most part the shroud encloses the entire perforated heat exchanging rear area of the radiator.
A fan shroud exit means is also provided having secured to the backwardly extending portion of the fan shroud and extending rearwardly thereof as well as outwardly. The particular contour of this exit section in combination with an axial flow fan located therein, allows the air stream to be converged and directed generally radially away from the engine compartment. Situated behind the fan is an air barrier means which in combination with the shroud exit section forces the fan to draw air through the radiator. As is apparent this invention is also applicable to a stationary engine where it is desired to achieve a high degree of performance from the fan blades.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which;
FIGURE 1 is a side elevation of an internal combustion engine showing the combination of my invention with a contoured shroud exit section attached to a vehicle;
FIGURE 2 is a fragmentary vertical section showing the relationship of the fan, the contoured exit section, and the air flow pattern without an air barrier; and FIGURE 3 is a fragmentary vertical section showing the air flow pattern with an air barrier.
While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment- On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of this invention as defined by the appended claims.
Turning first to Figure 1 there is shown a conventional water cooled heat producing internal combustion engine means 10 forwardly carried on longitudinally extend:ing parallel support means 12 of vehicle means 14.
~040~35 As shown herein vehicle means 14 is a tractor, however, as will hereafter become more apparent th;s invention can be applied to any type of vehicle employing a heat generating internal combustion engine or any other portable or stationary device requiring an air moving fan. For-wardly mounted is a water cooling radiator means 16 employed to dissipate the engine generated heat. Water flows between the water jacket on the engine (not shown) and the radiator through a series of fluid communicating means 18 and 20. In this particular embodiment sheet metal means 22 encircles engine means 10 thereby forming the engine compartment area means 24.
Carried at the forward end of engine means 10 is a fan shaft means 26 whereby power is delivered to drive fan means 28 (Figure 2). As is apparent, the particular mode whereby power is transmitted thereto is not critical and belts and pulleys could also be employed. As employed here, fan means 28 is a rotatable suction fan positioned opposite the radiator means 16, and normally creating a flow of air or drawing in a stream of cooling air rearwardly through the radiator with a subsequent axial discharge thereof. This axial flow of air is directed to the fan means by a shroud ~ means 30. The particular shape of the forward section 32 is dependent upon the shape and design of the perforated heat exchanging design of the radiator. The nature of the connection between the leading edge of 32 and the rear face 3~ of the radiator will be dependent upon the particular characteristics of these components, that is, some connections being provided with air gaps while others -~4~3S
are substantially sealed over the entire circumference of the enclosure. In the preferred form of this inven- -tion the entire perforated area is substantially sealed against the passage of air from any other direction except through the radiator. From the forward edges the shroud means 30 (be it a taper transition as shown or a box type~ converges rearwardly to a circular rear section 36. An air barrier means 31 is positioned rearwardly of the shroud exit section 38 as will be more fully hereafter discussed.
Referring now to Figure 2 wherein is more clearly shown a shroud exit means 38 extending rearwardly and outwardly from shroud edge 36. The connection between the shroud and the shroud exit can be achieved by any suitable means, however, it is desirable that such con-nection be relatively free of gaps or spaces which would allow the passage of air. Exit shroud means 38 includes a tubular means 40, an arcuated means portion 42 and a flat flange portion means 44. For the most part tubular means portion 40 forms the leading edge of the shroud exit means while arcuated means portion 42 still extend-ing generally rearwardly simultaneously extends outwardly around an arc the reference point of which is defined - as point 46. That is, arcuated section 42 has a general bell-shaped appearance being a section of a transition surface or some approximation thereof. In the preferred embodiment arcuated section 42 is a section of a constant radius arch. Flat flange portion 44 forms the trailing edge of exit shroud means 38 and has a major plane per-pendicular to that of tubular section 40. For purposes 1~)46~!~35 of simplicity, tubular means 40 will be hereafter referred to as the cylindrical throat means, arcuated portion 42 will be referred to as the radial expanding means and flat flange portion 44 will be referred to as radial flat means. Overall the entire fan shroud exit means 38 has a horn-like configuration.
The fan means 28 is rotatingly carried adjacent said radiator means and operable to establish a flow of cooling air therethrough.
Fan means 28 includes a plurality of fan blade means 48 (only one shown) as is well known in the art. As shown in Figure 2 fan means 28 is surrounded by said contoured fan shroud exit section 38. The enclosure of the fan means 28 within shroud means 30 is such that a front plane struck out by the leading edge 50 is coextensive and passes through the leading section of throat means 40 and a rear plane struck out by trailing edge 52 is about coextensive and parallel with said radial flat portion 44. It should be noted, however, that there is a plus or minus error factor involved in both of these values of about 12 percent oE AW. That is, the respective planes formed by the blade means can be within about 12 percent of optimum and still function satisactorily within the scope of this invention. Thus, within this range the deflected air stream will still be substan-tially radial. And generally about the outer two/thirds of the blade means is efficiently moving air through the radiator means.
While a beneficial effect is achieved by spacing the fan blades 48 with respect to the contoured shroud means 38 within the - aforementioned range, it has been determined that best results are obtained when the front or first vertical plane struck out by the leading edges 50 of the fan blades 48 pass through the juncture or merger between the entrance shroud means 32 and the cylindrical 3n exit shroud section 40. Even more determinative on the result is the relationship between the so-called rear plane struck out by the trailing edges 52 of the fan blades 48 and the radial flat flange shroud portion 44. Best overall performance is achieved when the rear or second vertical plane and the radial flat flange shroud portion or section 44 lie in the same plane.
The fol.lowing rela-tionship exists between these parameters: RF = AW/3, CF = AW/3, and R = 2A~/3 where RF is the length of the radial flat portion 44, CF is the length of the cylindrical throat section 40 and R is a radius of the radial expanding section 42 or distance from the reference point to the transition surface and AW is the projected axial width of fan 28.
The amount or relation of the fan means 28 -to the exit section means 38 is most conveniently expressed in terms of the amount of the fan which is exposed past the end of the shroud or projects rearwardly thereof (XE). It has been found that XE equal to zero gives optimum resul-ts; however, reasonable resul-ts can be achieved by having XE about equal to plus or minus 12 percent of AW. That is, as explained previously when the plane swept out by the rear edge is coextensive with the surface of the radial flat or within -the tolerance set forth. By changing the orientation of the fan with respect to the fan exit section it is also possible to direct the air stream, straight back, at an angle off radial, etc., depending on preference and need.
Considering the air flow patterns shown in E`igure 2 it is necessary to cut off the air flow, figura-tively shown as number 51, without the interruption of the generally radially flow pattern shown as number 53. As was previously stated the drawing of air in the hub region has a substantial detrimental effect on the eficiency of the fan. However, if a barrier is employed it should be positioned to cut off hub recirculation and not disrupt the flow pattern in the tip regions.
Referring to Figure 1 and 3, an air recirculation barrier means 31 is shown positioned behind the fan blade means 28. As shown in Figure 1 barrier means 31 is in the form of a flat disk which ~q~40~3S
has an overall diameter abou-t equal to that of the periphery of flange 44 of the shroud exit section 38. The barrier means is secured to frame means 12 by any suitable mode with a properly located opening for the fan drive shaft means 26.
It should be noted, however, barrier means or disk 31 could be mounted to the drive shaft 26 or in fact front portion means 37 of engine means 10 could be positioned and modified to perform the necessary function of preventing the recirculation of air in the hub region.
It has been determined that optimum performance of the cooling assembly so described can be achieved when barrier means 31 is positioned on a third vertical plane rear-wardly of the second plane containing the trailing edge means 52 of fan means 28, a distance corresponding to about 15 percent of the diameter of the circle generated by the tips of the fan means 28, which is an axial distance less than one-half of the diameter of the generated circle. The diameter of the barrier need only be substantially equal to that of the periphery of flange 44 in order to prevent the drawing in of air from the rearward areas into the hub portion.
The location of such a barrier means on a third plane which is generally opposite and parallel with the second plane containing the trailing edge of fan means 28 has been found to effectively retard hub recirculation without detrimentally effecting air flow patterns in the tip regions. This result is shown in Figure 3 by the air flow pattern as characterized by the number 39.
The barrier means 31 also serves as a safety guard for preventing accidental entry of hands etc. into the area adjacent fan means 28.
Thus it is apparent that there has been provided in accordance with the invention a shroud exit means that fully satisfies the objects, aims, and advantages set forth above. While the invention has been described in --10-- ' -104al~35 conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the fore~oin~ description. ~ccordingly, it is int~nded to emhrace all such alternatives, modifica-tions, and variations as fall within the spirit and broad scope of the appended claims.
1~
charges rearwardly. As a result of these conditions only about the middle 1/3 of the fan blade is effective in moving a cooling stream of air past the heat exchanger.
It has been shown, see copending Canadian application Serial Number 184,880, that a contoured shroud exit reduces horsepower requirements and generated noise and hampers the recirculation of air in the tip regions of the fan blade because of the radial air discharge pattern generated thereby.
Employment of Ihe contoured shroud exit thus increases the amount of the fan blade which is effective for moving air past the heat exchanger means.
It is therefore an object of this invention to provide an air barrier means to prevent the drawing in and recirculat-ion of air from behind the fan blade. Still another object of this invention is to provide an air barrier means which does not interere with the flow of air in the tip regions of the fan blade. ~et another object of this invention is to provide an air barrier means which functions as a safety guard. Another object of this invention is to provide a 2~ cooling assembly wherein a majority of the length of fan blade is functioning to move air each past the heat exchanger.
The invention thus contemplates a heat exchange apparatus which comprises a heat exchange means having front and rear faces, a shroud means including a forward section having forwardmost edge means arranged to encircle the rear face of the heat exchange means, and a rear exit shroud means having forwardmost edge means joined to rearwardmost edge means of the forward section. The exit shroud means includes, in successive sections, a generally cylindrical, axially extending throat section, an annular, radial curved section, and an annular, generally radially extending flat portion- A rotatable axial flow, suction-type fan encircled by the rear exit shroud means has a plurality of circumferentially spaced impeller blades (J3S
extending radially from a hub with each of the impeller blades having an effective axial width (AW) measured axially along the rotational axis of the fan between a first plane and a second plane. Those planes are axially spaced and parallel with respect to each other and disposed substantially normal to the rotational axis of the fan with the first and second planes extending radial-ly, respectively, through-points on the leading edges of the ;
impeller blades at the radial tip regions thereof and through points on the trailing edges of the impeller blades at the radial r lO- tip portions thereof. The second plane is substantially coincid-ent with the plane containing the annular, generally radially extending flat portion of the exit shroud means, and the following relationships exist: RF = AW/3 plus or minus 12 percent of AW, CF = AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW where RF is the radial length of the radially extending flat portion, CF is the axial length of the cylindrical throat section, and R is the radius of curvature of the radial curved section.
An air recirculation barrier means is axially spaced rearwardly of the second plane a predetermined distance less than one half of the diameter of the fan for obstructing axial flow of air in a forward direction from the region axially rearwardly of the fan hub when the fan is rotated.
In accordance with the preferred embodiment of this inven-tion a vehicle is provided having a liquid cooled internal com- ,~
bustion engine and a radiator cooling system for dissipating the heat produced. The radiator cooling system includes a standard r radiator, an axial flow fan facing the radiator and having a plurality of angular blades whereby air is drawn rearwardly through the radiator. A shroud rearwardly extends from the back face of the radiator to channel air through the radiator and hamper the fan from drawing air which has not passed through or at least come in contact with the perforated heat exchanging ~L040~35 surfaces of the radiator. For the most part the shroud encloses the entire perforated heat exchanging rear area of the radiator.
A fan shroud exit means is also provided having secured to the backwardly extending portion of the fan shroud and extending rearwardly thereof as well as outwardly. The particular contour of this exit section in combination with an axial flow fan located therein, allows the air stream to be converged and directed generally radially away from the engine compartment. Situated behind the fan is an air barrier means which in combination with the shroud exit section forces the fan to draw air through the radiator. As is apparent this invention is also applicable to a stationary engine where it is desired to achieve a high degree of performance from the fan blades.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which;
FIGURE 1 is a side elevation of an internal combustion engine showing the combination of my invention with a contoured shroud exit section attached to a vehicle;
FIGURE 2 is a fragmentary vertical section showing the relationship of the fan, the contoured exit section, and the air flow pattern without an air barrier; and FIGURE 3 is a fragmentary vertical section showing the air flow pattern with an air barrier.
While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment- On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of this invention as defined by the appended claims.
Turning first to Figure 1 there is shown a conventional water cooled heat producing internal combustion engine means 10 forwardly carried on longitudinally extend:ing parallel support means 12 of vehicle means 14.
~040~35 As shown herein vehicle means 14 is a tractor, however, as will hereafter become more apparent th;s invention can be applied to any type of vehicle employing a heat generating internal combustion engine or any other portable or stationary device requiring an air moving fan. For-wardly mounted is a water cooling radiator means 16 employed to dissipate the engine generated heat. Water flows between the water jacket on the engine (not shown) and the radiator through a series of fluid communicating means 18 and 20. In this particular embodiment sheet metal means 22 encircles engine means 10 thereby forming the engine compartment area means 24.
Carried at the forward end of engine means 10 is a fan shaft means 26 whereby power is delivered to drive fan means 28 (Figure 2). As is apparent, the particular mode whereby power is transmitted thereto is not critical and belts and pulleys could also be employed. As employed here, fan means 28 is a rotatable suction fan positioned opposite the radiator means 16, and normally creating a flow of air or drawing in a stream of cooling air rearwardly through the radiator with a subsequent axial discharge thereof. This axial flow of air is directed to the fan means by a shroud ~ means 30. The particular shape of the forward section 32 is dependent upon the shape and design of the perforated heat exchanging design of the radiator. The nature of the connection between the leading edge of 32 and the rear face 3~ of the radiator will be dependent upon the particular characteristics of these components, that is, some connections being provided with air gaps while others -~4~3S
are substantially sealed over the entire circumference of the enclosure. In the preferred form of this inven- -tion the entire perforated area is substantially sealed against the passage of air from any other direction except through the radiator. From the forward edges the shroud means 30 (be it a taper transition as shown or a box type~ converges rearwardly to a circular rear section 36. An air barrier means 31 is positioned rearwardly of the shroud exit section 38 as will be more fully hereafter discussed.
Referring now to Figure 2 wherein is more clearly shown a shroud exit means 38 extending rearwardly and outwardly from shroud edge 36. The connection between the shroud and the shroud exit can be achieved by any suitable means, however, it is desirable that such con-nection be relatively free of gaps or spaces which would allow the passage of air. Exit shroud means 38 includes a tubular means 40, an arcuated means portion 42 and a flat flange portion means 44. For the most part tubular means portion 40 forms the leading edge of the shroud exit means while arcuated means portion 42 still extend-ing generally rearwardly simultaneously extends outwardly around an arc the reference point of which is defined - as point 46. That is, arcuated section 42 has a general bell-shaped appearance being a section of a transition surface or some approximation thereof. In the preferred embodiment arcuated section 42 is a section of a constant radius arch. Flat flange portion 44 forms the trailing edge of exit shroud means 38 and has a major plane per-pendicular to that of tubular section 40. For purposes 1~)46~!~35 of simplicity, tubular means 40 will be hereafter referred to as the cylindrical throat means, arcuated portion 42 will be referred to as the radial expanding means and flat flange portion 44 will be referred to as radial flat means. Overall the entire fan shroud exit means 38 has a horn-like configuration.
The fan means 28 is rotatingly carried adjacent said radiator means and operable to establish a flow of cooling air therethrough.
Fan means 28 includes a plurality of fan blade means 48 (only one shown) as is well known in the art. As shown in Figure 2 fan means 28 is surrounded by said contoured fan shroud exit section 38. The enclosure of the fan means 28 within shroud means 30 is such that a front plane struck out by the leading edge 50 is coextensive and passes through the leading section of throat means 40 and a rear plane struck out by trailing edge 52 is about coextensive and parallel with said radial flat portion 44. It should be noted, however, that there is a plus or minus error factor involved in both of these values of about 12 percent oE AW. That is, the respective planes formed by the blade means can be within about 12 percent of optimum and still function satisactorily within the scope of this invention. Thus, within this range the deflected air stream will still be substan-tially radial. And generally about the outer two/thirds of the blade means is efficiently moving air through the radiator means.
While a beneficial effect is achieved by spacing the fan blades 48 with respect to the contoured shroud means 38 within the - aforementioned range, it has been determined that best results are obtained when the front or first vertical plane struck out by the leading edges 50 of the fan blades 48 pass through the juncture or merger between the entrance shroud means 32 and the cylindrical 3n exit shroud section 40. Even more determinative on the result is the relationship between the so-called rear plane struck out by the trailing edges 52 of the fan blades 48 and the radial flat flange shroud portion 44. Best overall performance is achieved when the rear or second vertical plane and the radial flat flange shroud portion or section 44 lie in the same plane.
The fol.lowing rela-tionship exists between these parameters: RF = AW/3, CF = AW/3, and R = 2A~/3 where RF is the length of the radial flat portion 44, CF is the length of the cylindrical throat section 40 and R is a radius of the radial expanding section 42 or distance from the reference point to the transition surface and AW is the projected axial width of fan 28.
The amount or relation of the fan means 28 -to the exit section means 38 is most conveniently expressed in terms of the amount of the fan which is exposed past the end of the shroud or projects rearwardly thereof (XE). It has been found that XE equal to zero gives optimum resul-ts; however, reasonable resul-ts can be achieved by having XE about equal to plus or minus 12 percent of AW. That is, as explained previously when the plane swept out by the rear edge is coextensive with the surface of the radial flat or within -the tolerance set forth. By changing the orientation of the fan with respect to the fan exit section it is also possible to direct the air stream, straight back, at an angle off radial, etc., depending on preference and need.
Considering the air flow patterns shown in E`igure 2 it is necessary to cut off the air flow, figura-tively shown as number 51, without the interruption of the generally radially flow pattern shown as number 53. As was previously stated the drawing of air in the hub region has a substantial detrimental effect on the eficiency of the fan. However, if a barrier is employed it should be positioned to cut off hub recirculation and not disrupt the flow pattern in the tip regions.
Referring to Figure 1 and 3, an air recirculation barrier means 31 is shown positioned behind the fan blade means 28. As shown in Figure 1 barrier means 31 is in the form of a flat disk which ~q~40~3S
has an overall diameter abou-t equal to that of the periphery of flange 44 of the shroud exit section 38. The barrier means is secured to frame means 12 by any suitable mode with a properly located opening for the fan drive shaft means 26.
It should be noted, however, barrier means or disk 31 could be mounted to the drive shaft 26 or in fact front portion means 37 of engine means 10 could be positioned and modified to perform the necessary function of preventing the recirculation of air in the hub region.
It has been determined that optimum performance of the cooling assembly so described can be achieved when barrier means 31 is positioned on a third vertical plane rear-wardly of the second plane containing the trailing edge means 52 of fan means 28, a distance corresponding to about 15 percent of the diameter of the circle generated by the tips of the fan means 28, which is an axial distance less than one-half of the diameter of the generated circle. The diameter of the barrier need only be substantially equal to that of the periphery of flange 44 in order to prevent the drawing in of air from the rearward areas into the hub portion.
The location of such a barrier means on a third plane which is generally opposite and parallel with the second plane containing the trailing edge of fan means 28 has been found to effectively retard hub recirculation without detrimentally effecting air flow patterns in the tip regions. This result is shown in Figure 3 by the air flow pattern as characterized by the number 39.
The barrier means 31 also serves as a safety guard for preventing accidental entry of hands etc. into the area adjacent fan means 28.
Thus it is apparent that there has been provided in accordance with the invention a shroud exit means that fully satisfies the objects, aims, and advantages set forth above. While the invention has been described in --10-- ' -104al~35 conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the fore~oin~ description. ~ccordingly, it is int~nded to emhrace all such alternatives, modifica-tions, and variations as fall within the spirit and broad scope of the appended claims.
1~
Claims (9)
1. A heat exchange apparatus comprising:
a heat exchange means having front and rear faces;
a shroud means including a forward section having forwardmost edge means arranged to encircle said rear face of said heat exchange means, and a rear exit shroud means having forwardmost edge means joined to rearwardmost edge means of said forward section, said exit shroud means including, in successive sections, a generally cylindrical, axially extending throat section, an annular, radial curved section, and an annular, generally radially extending flat portion;
a rotatable axial flow, suction-type fan encircled by said rear exit shroud means having a plurality of circumferent-ially spaced impeller blades extending radially from a hub, each of said impeller blades having an effective axial width (AW) measured axially along the rotational axis of the fan between a first plane and a second plane, said planes being axially spaced and parallel with respect to each other and disposed substantially normal to the rotational axis of the fan, said first and second planes extending radially, respectively, through points on the leading edges of the impeller blades at the radial tip regions thereof and through points on the trailing edges of the impeller blades at the radial tip portions thereof, said second plane being substantially coincident with the plane containing said annular, generally radially extending flat portion of said exit shroud means, and the following relationships exist: RF = AW/3 plus or minus 12 percent of AW, CF = AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW where RF is the radial length of the radially extending flat portion, CF is the axial length of the cylindrical throat section, and R is the radius of curvat-ure of the radial curved section; and air recirculation barrier means axially spaced rearwardly of said second plane a predetermined distance less than one half of the diameter of said fan for obstructing axial flow of air in a forward direction from the region axially rearwardly of said fan hub when said fan is rotated.
a heat exchange means having front and rear faces;
a shroud means including a forward section having forwardmost edge means arranged to encircle said rear face of said heat exchange means, and a rear exit shroud means having forwardmost edge means joined to rearwardmost edge means of said forward section, said exit shroud means including, in successive sections, a generally cylindrical, axially extending throat section, an annular, radial curved section, and an annular, generally radially extending flat portion;
a rotatable axial flow, suction-type fan encircled by said rear exit shroud means having a plurality of circumferent-ially spaced impeller blades extending radially from a hub, each of said impeller blades having an effective axial width (AW) measured axially along the rotational axis of the fan between a first plane and a second plane, said planes being axially spaced and parallel with respect to each other and disposed substantially normal to the rotational axis of the fan, said first and second planes extending radially, respectively, through points on the leading edges of the impeller blades at the radial tip regions thereof and through points on the trailing edges of the impeller blades at the radial tip portions thereof, said second plane being substantially coincident with the plane containing said annular, generally radially extending flat portion of said exit shroud means, and the following relationships exist: RF = AW/3 plus or minus 12 percent of AW, CF = AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW, and R = 2AW/3 plus or minus 12 percent of AW where RF is the radial length of the radially extending flat portion, CF is the axial length of the cylindrical throat section, and R is the radius of curvat-ure of the radial curved section; and air recirculation barrier means axially spaced rearwardly of said second plane a predetermined distance less than one half of the diameter of said fan for obstructing axial flow of air in a forward direction from the region axially rearwardly of said fan hub when said fan is rotated.
2. A heat exchange apparatus as set forth in Claim 1, wherein:
said barrier means lies substantially in a plane spaced and substantially parallel with respect to said second plane.
said barrier means lies substantially in a plane spaced and substantially parallel with respect to said second plane.
3. A heat exchange apparatus as set forth in Claim 1, wherein:
said air recirculation barrier means is generally in a form of a flat and substantially imperforate disk, said disk lying substantially in a radial plane spaced and parallel with respect to said second radial plane.
said air recirculation barrier means is generally in a form of a flat and substantially imperforate disk, said disk lying substantially in a radial plane spaced and parallel with respect to said second radial plane.
4. A heat exchange apparatus as set forth in Claim 3, wherein:
said predetermined distance said air recirculation barrier means is axially spaced rearwardly of said second plane is about 15 percent of the diameter of said fan.
said predetermined distance said air recirculation barrier means is axially spaced rearwardly of said second plane is about 15 percent of the diameter of said fan.
5. A heat exchange apparatus as set forth in Claim 3, wherein:
said radial flat portion has its radially outermost periphery defined by a circle; and said flat and substantially imperforate disk has its radially outermost periphery defined by a circle having sub-stantially the same diameter as said circle defining the radially outermost periphery of said radial flat portion of said shroud means.
said radial flat portion has its radially outermost periphery defined by a circle; and said flat and substantially imperforate disk has its radially outermost periphery defined by a circle having sub-stantially the same diameter as said circle defining the radially outermost periphery of said radial flat portion of said shroud means.
6. A heat exchange apparatus as set forth in Claim 5, wherein:
said predetermined distance said air recirculation barrier means is axially spaced rearwardly of said second plane is about 15 percent of the diameter of said fan.
said predetermined distance said air recirculation barrier means is axially spaced rearwardly of said second plane is about 15 percent of the diameter of said fan.
7. A heat exchange apparatus as set forth in Claim 6, wherein:
said air recirculation barrier means is fixed with respect to said shroud means.
said air recirculation barrier means is fixed with respect to said shroud means.
8. A heat exchange apparatus as set forth in Claim 6, wherein:
said air recirculation barrier means is rotatable in unison with said fan blades.
said air recirculation barrier means is rotatable in unison with said fan blades.
9. A heat exchange apparatus as set forth in Claim 2 or Claim 3, wherein said second plane may be axially spaced from and on either axial side of said radial plane containing said radially extending flat portion of said shroud means a distance of 12 percent of AW.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US44719274A | 1974-03-01 | 1974-03-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1040035A true CA1040035A (en) | 1978-10-10 |
Family
ID=23775359
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA213,118A Expired CA1036447A (en) | 1974-03-01 | 1974-11-06 | Recirculation barrier for a heat transfer system |
| CA290,975A Expired CA1040035A (en) | 1974-03-01 | 1977-11-16 | Recirculation barrier for a heat transfer system |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA213,118A Expired CA1036447A (en) | 1974-03-01 | 1974-11-06 | Recirculation barrier for a heat transfer system |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS50121634A (en) |
| AU (1) | AU474370B2 (en) |
| BR (1) | BR7501203A (en) |
| CA (2) | CA1036447A (en) |
| DE (1) | DE2505563B2 (en) |
| FR (1) | FR2262607B2 (en) |
| GB (1) | GB1471503A (en) |
| IT (1) | IT1026476B (en) |
| NL (1) | NL156213B (en) |
| SE (1) | SE409485B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57112025U (en) * | 1980-12-27 | 1982-07-10 | ||
| DE3447195A1 (en) * | 1984-12-22 | 1986-07-03 | M A N Nutzfahrzeuge GmbH, 8000 München | COOLING DEVICE WITH AXIAL FAN IN CAPSULE DESIGN |
| DE3503220C1 (en) * | 1985-01-31 | 1986-07-03 | Daimler-Benz Ag, 7000 Stuttgart | Radiator frame arranged on the cooler of a liquid-cooled internal combustion engine |
| US5105639A (en) * | 1989-02-23 | 1992-04-21 | Spiro America Inc. | Apparatus for forming spiral pipe |
| DE4137703C1 (en) * | 1991-11-15 | 1992-12-10 | Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De | |
| US6192839B1 (en) * | 1997-09-19 | 2001-02-27 | Hitachi Construction Machinery Co., Ltd. | Cooling apparatus for construction machine, and construction machine |
| US6827547B2 (en) | 2003-01-29 | 2004-12-07 | Borgwarner Inc. | Engine cooling fan having improved airflow characteristics |
| USD805107S1 (en) | 2016-12-02 | 2017-12-12 | U.S. Farathane Corporation | Engine fan shroud |
| CN111648854A (en) * | 2020-06-09 | 2020-09-11 | 安徽江淮银联重型工程机械有限公司 | Combined radiator for large forklift |
-
1974
- 1974-11-06 CA CA213,118A patent/CA1036447A/en not_active Expired
- 1974-12-05 AU AU76119/74A patent/AU474370B2/en not_active Expired
- 1974-12-18 NL NL7416536A patent/NL156213B/en not_active IP Right Cessation
-
1975
- 1975-01-14 GB GB153675A patent/GB1471503A/en not_active Expired
- 1975-01-27 IT IT4785675A patent/IT1026476B/en active
- 1975-02-10 DE DE19752505563 patent/DE2505563B2/en not_active Ceased
- 1975-02-27 SE SE7502245A patent/SE409485B/en unknown
- 1975-02-28 FR FR7506250A patent/FR2262607B2/fr not_active Expired
- 1975-02-28 BR BR7501203A patent/BR7501203A/en unknown
- 1975-03-01 JP JP2553675A patent/JPS50121634A/ja active Pending
-
1977
- 1977-11-16 CA CA290,975A patent/CA1040035A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1471503A (en) | 1977-04-27 |
| FR2262607A2 (en) | 1975-09-26 |
| FR2262607B2 (en) | 1979-10-19 |
| AU474370B2 (en) | 1976-07-22 |
| NL156213B (en) | 1978-03-15 |
| IT1026476B (en) | 1978-09-20 |
| JPS50121634A (en) | 1975-09-23 |
| SE7502245A (en) | 1975-09-02 |
| BR7501203A (en) | 1975-12-09 |
| DE2505563B2 (en) | 1976-06-16 |
| SE7502245L (en) | 1975-09-02 |
| NL7416536A (en) | 1975-09-03 |
| SE409485B (en) | 1979-08-20 |
| CA1036447A (en) | 1978-08-15 |
| AU7611974A (en) | 1976-06-10 |
| DE2505563A1 (en) | 1975-09-04 |
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