JP2012241570A - Shroud for cooling fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control deterioration of cooling performance, and to control an increase of noise.SOLUTION: A shroud 1 covers between around the outer periphery of a cooling fan 15 which generates cooling wind in a direction toward a rotary shaft 15a and a heat exchanger 11. The shroud 1 includes: a shroud body 20 mounted on the heat exchanger 11; and a duct 30 provided inside the shroud body 20 and arranged around the outer periphery of the cooling fan 15. The duct 30 includes an opening edge 40 and a cooling piping 50. The opening edge 40 forms an opening in which the cooling fan 15 is arranged in the inside thereof and is cylindrically formed, centering around the rotary shaft 15a of the cooling fan 15. The cooling piping 50 is arranged, surrounding the outer periphery of the cooling fan 15 and allows a cooling medium to pass through.

Description

  The present invention relates to a shroud that covers the periphery of a cooling fan and a heat exchanger.

  6 and 7 of Patent Document 1 describe a cooling device provided in an engine of a construction machine or the like. The cooling device includes a cooling fan that is rotationally driven by the engine, a heat exchanger, and a shroud that covers a space between the cooling fan and the heat exchanger.

  FIG. 10A shows a cooling device 510 provided with a conventional box-type shroud 501. FIG.10 (b) is F10b arrow line view shown to Fig.10 (a). Fig.11 (a) is an enlarged view of the part F11a enclosed with the broken line in Fig.10 (a). As shown in FIGS. 10B and 11A, the shroud 501 includes a side surface 21 and a vertical surface 22 (a surface perpendicular to the horizontal plane). An opening 22o is formed in the vertical surface 22, and the cooling fan 15 is disposed inside the opening 22o.

JP 2009-73468 A

  The shroud 501 shown in FIGS. 10 and 11 has the following problem. As shown in FIG. 11A, the cooling air flows between the end of the vertical surface 22 on the cooling fan 15 side (the edge of the opening 22 o) and the cooling fan 15. The direction of the flow of the cooling air changes abruptly with the vertical plane 22 as a boundary, and a large disturbance (separation or vortex) occurs in the flow of the cooling air. Then, ventilation resistance and noise increase around the opening 22o.

  11 (b) and 11 (c) show a technique for improving the cooling air disturbance. In the technique shown in FIG. 11B, the edge of the opening 22o of the shroud 501 is cylindrical. Further, in the technique shown in FIG. 11 (c), the edge of the opening 22o has a bell mouth shape. By making the edge of the opening 22o cylindrical or bell mouth like these, it is possible to suppress an increase in ventilation resistance and noise around the opening 22o. However, as will be described below, these effects are offset by the addition of heat exchangers.

  A large number of heat exchangers 11 shown in FIG. 10A are installed, such as an engine cooling radiator 11a, an oil cooler for cooling hydraulic oil, an intercooler 11b, and an air conditioner condenser 11c for air conditioning in the cab. There is a case. Further, in a hybrid construction machine or the like, a heat exchanger 11 for cooling a motor, a bearing, or the like may be added. When a large number of heat exchangers 11 are installed in this way, the ventilation resistance against the cooling air passing through the heat exchanger 11 increases. Then, there is a possibility that the effect of suppressing the ventilation resistance due to the shape of the edge of the opening 22o being a bell mouth shape or the like may be offset. As a result, the amount of cooling air cannot be secured, and the cooling performance of the cooling device may be reduced.

  Further, when the number of rotations of the cooling fan is increased in order to secure the air volume of the cooling air, the sound generated from the cooling fan increases. In particular, the fan pitch sound (prominent peak) resulting from the number of rotations of the cooling fan and the number of blades of the cooling fan may become prominent.

  Then, an object of this invention is to provide the shroud for cooling fans which can suppress the fall of cooling performance and can suppress the increase in noise.

  The present invention is a shroud that covers a space between the periphery of a cooling fan that generates cooling air in the direction of the rotation axis and a heat exchanger. The shroud includes a shroud body portion attached to the heat exchanger, and a duct portion provided inside the shroud body portion and disposed around the outer periphery of the cooling fan. The duct portion includes an opening edge and a cooling pipe. The opening edge forms an opening in which the cooling fan is disposed inside, and is formed in a cylindrical shape with the rotation axis of the cooling fan as an axis. The cooling pipe is disposed so as to surround the outer periphery of the cooling fan and allows the cooling medium to pass therethrough.

  In the cooling fan shroud of the present invention, it is possible to suppress a decrease in cooling performance and to suppress an increase in noise.

It is a schematic diagram which shows the cooling device provided with the shroud. FIG. 2 is an enlarged view of the F2a portion shown in FIG. It is F3 arrow line view of shrouds etc. which are shown in FIG. It is a graph which shows the noise level of the construction machine provided with the cooling device shown in FIG. FIG. 3 is a diagram corresponding to FIG. 2 of the second embodiment. It is FIG. 2 equivalent figure of 3rd Embodiment. FIG. 6 is a diagram corresponding to FIG. 3 of the third embodiment. It is FIG. 3 equivalent view of the modification of 3rd Embodiment. FIG. 9 is a diagram corresponding to FIG. 3 of the fourth embodiment. It is a schematic diagram which shows the cooling device provided with the conventional shroud. FIG. 3 is a view corresponding to FIG. 2 of a conventional shroud.

(First embodiment)
The shroud 1 of 1st Embodiment is demonstrated with reference to FIGS. In FIG. 2, the upper pipe P3, the lower pipe P4, and the like are omitted. In FIG. 3, the cooling fan 15 is indicated by a two-dot chain line in order to distinguish the shroud 1 and the cooling fan 15. First, the cooling device 10 provided with the shroud 1 will be described.

  As shown in FIG. 1, the cooling device 10 is provided in an engine E of a construction machine (working machine) such as a hydraulic excavator. The cooling device 10 includes a heat exchanger 11, a cooling fan 15 that is rotationally driven by the engine E, and a shroud 1 (cooling fan shroud) that covers the space between the heat exchanger 11 and the cooling fan 15. The outline of the operation of the cooling device 10 is as follows. The cooling fan 15 is rotationally driven by the engine E to generate cooling air. The cooling air flows from the heat exchanger 11 side to the engine E side. Then, the cooling medium in the heat exchanger 11 is cooled, and the engine E is also cooled. That is, the cooling device 10 is an air suction type cooling device and an air discharge type cooling device. Hereinafter, the upstream side of the cooling air is referred to as “front”, and the downstream side of the cooling air is referred to as “rear”.

  The heat exchanger 11 is a device that cools a cooling medium (heat exchange medium). The heat exchanger 11 that cools the cooling medium includes, for example, the following (a) to (d). (A) A radiator that cools engine coolant for cooling the engine E. (B) An oil cooler that cools hydraulic oil of a hydraulic machine such as a hydraulic pump. (C) An intercooler that cools the compressed air. (D) An air conditioner condenser that cools the refrigerant for air conditioning in the cab of the construction machine. The heat exchanger 11 may be one or plural (see FIG. 10A). The heat exchanger 11 operates as follows. A cooling medium is supplied to the heat exchanger 11 via the pipe P1. The cooling medium passes through the heat exchanger 11 and is cooled by the cooling air. A cooling medium is discharged | emitted from the heat exchanger 11 via the piping P2.

  The cooling fan 15 is a blower that generates cooling air in the direction of the rotation shaft 15a. The direction of the cooling air may be a direction having a component in the direction of the rotating shaft 15a, or may be a direction substantially along the direction of the rotating shaft 15a. The cooling fan 15 is an axial flow fan and may be a mixed flow fan. As shown in FIG. 3, the cooling fan 15 includes a shaft portion 16 disposed in the center portion and a plurality of blades 17 fixed to the shaft portion 16 (in order to avoid complexity, a plurality of blades are shown in FIG. 3. Only one blade 17 out of 17 is provided with a reference numeral). As shown in FIG. 1, the cooling fan 15 has a shaft portion 16 (see FIG. 3) attached to the engine E, and is disposed between the heat exchanger 11 and the engine E. The cooling fan 15 is rotationally driven by utilizing a part of the driving force of the engine E, sucks air from the outside (from the front) through the heat exchanger 11 and discharges the air to the engine E side (rear).

  The shroud 1 (cooling fan shroud) is a member that covers the periphery of the cooling fan 15 and the heat exchanger 11. The shroud 1 is a member that guides the cooling air so that a part of the cooling air does not diffuse so that the entire flow rate of the cooling air sucked by the cooling fan 15 passes through the heat exchanger 11. The shroud 1 includes a shroud body portion 20 and a duct portion 30 provided inside the shroud body portion 20.

  The shroud main body 20 is a part attached to the heat exchanger 11. The shroud main body 20 may be directly fixed to the heat exchanger 11 or may be indirectly fixed to the heat exchanger 11 through another member between the shroud main body 20 and the heat exchanger 11. The shroud main body 20 is fixed to, for example, the rear end and the outer periphery of the heat exchanger 11. The shroud body 20 is box-shaped. As shown in FIG. 2A, the shroud main body 20 includes a side surface 21 that extends rearward from the rear end of the heat exchanger 11 and a vertical surface 22 that extends from the rear end of the side surface 21 toward the cooling fan 15. Hereinafter, the side closer to the rotating shaft 15a of the cooling fan 15 is referred to as “inside the shroud”, and the side farther from the rotating shaft 15a is referred to as “outside the shroud”. The vertical surface 22 is a surface perpendicular to the horizontal plane. A duct portion 30 is provided inside the shroud of the vertical surface 22. The shroud main body 20 may not have a structure including the side surface 21 and the vertical surface 22 (a structure in which the cross section is bent). For example, the shroud main body 20 may have a shape that gently connects from the attachment portion with the heat exchanger 11 to the duct portion 30.

  The duct portion 30 is a portion provided inside the shroud main body portion 20. The duct portion 30 is disposed around the outer periphery of the cooling fan 15. The duct portion 30 and the shroud main body portion 20 may be integrated or separated. As shown in FIG. 3, the duct portion 30 is formed in a circular shape (ring shape, tubular shape). The inner circumference of the duct part 30 is larger than the outer dimension (outer circumference) of the cooling fan 15. That is, a gap is formed between the duct portion 30 and the cooling fan 15. As shown in FIG. 2A, the duct part 30 includes a duct part front surface 31, an opening edge 40 which is a surface inside the shroud, a duct part rear surface 35, and a cooling pipe 50.

  The duct portion front surface 31 is a surface that extends inward from the shroud inside of the vertical surface 22 of the shroud main body portion 20.

  As shown in FIGS. 2A and 3, the opening edge 40 is a portion that forms an opening in which the cooling fan 15 is disposed. The opening edge 40 is an outer edge of this opening. The opening edge 40 is formed along the flow of cooling air by the cooling fan 15. The opening edge 40 is formed in a cylindrical shape (cylindrical shape) around the rotation shaft 15 a of the cooling fan 15. The opening edge 40 has a circular duct shape. That is, as shown in FIG. 2A, the opening edge 40 is formed so as to extend rearward from the shroud inner end portion of the duct portion front surface 31. The width of the opening edge 40 in the front-rear direction is, for example, approximately the same as the width of the cooling fan 15 in the front-rear direction. The front side (front half) of the opening edge 40 is referred to as “opening edge front part 40f”, and the rear side (rear half) part of the opening edge 40 is referred to as “opening edge rear part 40r”.

  The cooling pipe 50 is a pipe through which a cooling medium passes. In addition, in FIG. 1 etc., the part through which the cooling medium inside the cooling pipe 50 passes is shown by oblique lines. As shown in FIG. 3, the cooling pipe 50 is disposed so as to surround the outer periphery of the cooling fan 15. An upper pipe P3 and a lower pipe P4 are connected to the cooling pipe 50. Hereinafter, the cooling pipe 50 will be further described.

  The cooling pipe 50 is connected to the upper pipe P3 at the upper part 50t of the cooling pipe 50. The cooling pipe 50 is connected to the lower pipe P4 at the lower part 50b of the cooling pipe 50. The cooling medium passes (flows) through the cooling pipe 50 as follows. The cooling medium is supplied from the upper pipe P3 to the upper part 50t of the cooling pipe 50. The cooling medium branches left and right at the upper portion 50t of the cooling pipe 50, passes through the left and right arc-shaped portions of the cooling pipe 50, and merges at the lower portion 50b of the cooling pipe 50. Then, the cooling medium is discharged from the lower part 50b of the cooling pipe 50 to the lower pipe P4.

  As shown in FIG. 1, for example, the upper pipe P <b> 3 branches from the pipe P <b> 1 connected to the heat exchanger 11. The lower piping P4 branches from the piping P2 connected to the heat exchanger 11. Specifically, for example, engine cooling water (cooling medium) is supplied to the radiator (heat exchanger 11) through the pipe P1, and engine cooling water is also supplied to the cooling pipe 50 through the upper pipe P3. . Then, the engine coolant flows from the radiator (heat exchanger 11) through the pipe P2 to the engine E, and the engine coolant flows from the cooling pipe 50 to the engine E through the lower pipe P4 and the pipe P2.

  Further, for example, the upper pipe P3 and the lower pipe P4 may be connected to a dedicated pipe that does not branch from the pipe P1 and the pipe P2. That is, the cooling medium may be cooled only by the cooling pipe 50 without using the heat exchanger 11. Specifically, for example, a cooling medium for an electric motor or a bearing (both not shown) is allowed to flow only through the cooling pipe 50.

  As shown in FIG. 3, the cooling pipe 50 is disposed so as to surround the outer periphery of the cooling fan 15. The cooling pipe 50 has a circular shape when viewed from the direction of the rotating shaft 15a of the cooling fan 15 (front-rear direction). The cooling pipe 50 is disposed in the vicinity of the outer periphery of the cooling fan 15. The cooling pipe 50 is disposed at a position where heat is transferred from the cooling pipe 50 to the opening edge 40. The cooling pipe 50 is provided integrally or separately from the opening edge 40 along the opening edge 40. When the cooling pipe 50 and the opening edge 40 are integrated, a portion inside the shroud of the cooling pipe 50 is the opening edge 40. When the cooling pipe 50 and the opening edge 40 are separate bodies, the inner portion of the cooling pipe 50 is in contact with the opening edge 40, or the same part is disposed adjacent to the opening edge 40 in the vicinity of the opening edge 40. . Hereinafter, the phrase “the cooling pipe 50 is provided at the opening edge 40” means that the cooling pipe 50 is provided integrally or separately from the opening edge 40 as described above. As shown in FIG. 2A, the cooling pipe 50 is provided on the opening edge 40 from the front end to the rear end of the opening edge 40. The cross section of the cooling pipe 50 shown in FIG. 2A is, for example, a substantially rectangular shape. More specifically, the cooling pipe 50 has a circular shape when viewed from the front-rear direction (see FIG. 3), and a cross-section (see FIG. 2A) of the cooling pipe 50 viewed from the direction along the circular circumference is, for example, It is almost rectangular. Hereinafter, the cross section of the shroud 1 viewed from the direction along the circumference is referred to as “cross section D” (the cross section shown in FIG. 2A is an example of the cross section D). The rear surface of the cooling pipe 50, that is, the rear surface of the duct portion 30 is referred to as a “duct portion rear surface 35”.

(Modification of opening edge)
FIG. 2B shows a shroud 1 having a modified opening edge 60. The cylindrical opening edge 40 shown in FIG. 2A can be transformed into a bell mouth-like opening edge 60 shown in FIG.

  The opening edge 60 is formed in a bell mouth shape (cylindrical shape) around the rotation shaft 15 a of the cooling fan 15. The opening edge 60 is formed in a trumpet shape. The opening edge 60 has a circular cross section D. The “arc shape” includes, for example, an elliptical arc or a curve close to an arc. The front part of the opening edge 60 is referred to as “opening edge front part 60f”, and the rear part of the opening edge 60 is referred to as “opening edge rear part 60r”.

  The cooling pipe 70 is formed in a shape corresponding to the opening edge 60. The front surface of the cooling pipe 70 in the cross section D, the inner surface of the shroud, and the rear surface are arcuate. The shape of the entire cooling pipe 70 in the cross section D is, for example, a semicircular shape (a circular shape or the like may be used).

(Other variations of the opening edge)
The shape of the opening edge 40 shown in FIG. For example, the opening edge 40 may have a cylindrical shape (not shown) having a taper shape with the rotating shaft 15a of the cooling fan 15 as an axis. Further, for example, the shape of the cross section D of the opening edge 40 may be a combination of an arc shape and a straight line. For example, it is good also as a shape which combined the cylindrical opening edge 40 and the bellmouth-shaped opening edge 60 (refer FIG.2 (b)).

(Experiment)
FIG. 4 shows the measurement results of the noise level around the hydraulic excavator when the shroud 1 and the like are installed on a large hydraulic excavator (not shown). As shown in FIG. 11A, the result of the case (comparative example) provided with a shroud 501 not provided with a cylindrical or bell mouth-shaped opening edge is indicated by a broken line in the graph of FIG. As shown in FIG. 1, the result when the shroud 1 including the cylindrical opening edge 40 is provided (the present invention) is shown by a solid line in the graph of FIG. 4. The result was as follows. In the comparative example, fan pitch sound (prominent peak) resulting from the number of rotations of the cooling fan 15 (see FIG. 3) and the number of blades 17 of the cooling fan 15 is generated in the 300 Hz band. On the other hand, in this invention, it turns out that this fan pitch sound is reducing.

(Effect 1)
Next, the effect of the shroud 1 shown in FIG. 1 will be described. The shroud 1 covers the periphery of the cooling fan 15 that generates cooling air in the direction of the rotating shaft 15 a and the heat exchanger 11. The shroud 1 includes a shroud main body portion 20 attached to the heat exchanger 11 and a duct portion 30 provided inside the shroud main body portion 20.

The duct portion 30 is disposed around the outer periphery of the cooling fan 15. The duct portion 30 includes an opening edge 40 (or an opening edge 60 shown in FIG. 2B) that forms an opening in which the cooling fan 15 is disposed inside. The opening edge 40 is formed in a cylindrical shape with the rotation shaft 15 a of the cooling fan 15 as an axis. Therefore, the cooling air around the outer periphery of the cooling fan 15 tends to flow along the opening edge 40. Therefore, generation | occurrence | production of peeling and eddy current around the opening edge 40 is suppressed. Therefore, heat is easily dissipated from the opening edge 40.
In addition, since generation | occurrence | production of peeling and eddy current around the opening edge 40 is suppressed, like the conventional shroud 501 shown in FIGS. 11B and 11C, the ventilation resistance and noise around the opening edge 40 are suppressed. it can.

  As shown in FIG. 3, the duct portion 30 is disposed around the outer periphery of the cooling fan 15. Here, the cooling air generated by the cooling fan 15 has the fastest flow velocity on the outer periphery of the cooling fan 15 (the tip of the blade 17). Therefore, heat is easily dissipated from the opening edge 40 of the duct part 30.

  The duct portion 30 includes a cooling pipe 50 (or a cooling pipe 70 shown in FIG. 2B, which is shown in FIG. 2B) through which the cooling medium passes. Further, as described above, heat is easily dissipated from the opening edge 40. Therefore, the heat transmitted from the cooling pipe 50 to the opening edge 40 is easily dissipated from the opening edge 40. Therefore, the cooling medium passing through the cooling pipe 50 is easily cooled.

  As shown in FIG. 3, the cooling pipe 50 is disposed so as to surround the outer periphery of the cooling fan 15. Therefore, compared with the case where the cooling pipe 50 is arranged only in the vicinity of a part of the outer periphery of the cooling fan 15, the cooling medium passing through the cooling pipe 50 is more easily cooled.

  As described above, in the shroud 1 shown in FIG. 1, the cooling medium can be cooled by the duct portion 30. Therefore, there is no need to add a heat exchanger 11 for cooling the cooling medium. Therefore, an increase in ventilation resistance due to the addition of the heat exchanger 11 can be suppressed, and a decrease in the amount of cooling air due to an increase in ventilation resistance can be suppressed. Therefore, the fall of the cooling performance (cooling performance of the cooling device 10 provided with the shroud 1) by the fall of the air volume of cooling air can be suppressed.

  As described above, it is possible to suppress a decrease in the amount of cooling air due to the addition of the heat exchanger 11. Therefore, it is not necessary to increase the rotational speed of the cooling fan 15 in order to compensate for the decrease in the amount of cooling air. Therefore, an increase in noise due to an increase in the rotation speed of the cooling fan 15 can be suppressed.

(Second Embodiment)
A shroud 201 of the second embodiment will be described with reference to FIG.
In the shroud 1 shown in FIG. 1, the cooling pipe 50 is provided over the entire front and rear width of the opening edge 40. In the shroud 201 shown in FIG. 5A, a cooling pipe 250 is provided at a part of the opening edge 40, and a heat radiating plate 241 is formed at the other part of the opening edge 40. Hereinafter, the difference will be further described.

  The heat dissipation plate 241 is a component of the opening edge 40 and is a plate that promotes heat dissipation in the duct portion 30. A portion of the opening edge 40 where the cooling pipe 250 is not provided functions as the heat radiating plate 241 (utilized as the heat radiating plate 241). That is, the cooling pipe 250 is provided in the opening edge front portion 40f of the opening edge 40, and the opening edge rear portion 40r is the heat radiating plate 241 where the cooling pipe 250 is not provided in the opening edge rear portion 40r. For example, when the flow rate of the cooling medium passing through the cooling pipe 50 shown in FIG. 1 is small, the cooling pipe 50 can be narrowed like the cooling pipe 250 shown in FIG. As a result of narrowing the cooling pipe 250, the heat radiating plate 241 is formed.

  The heat sink 241 operates as follows. As described above, the cooling air flows along the opening edge 40, and as a result, the cooling air flows along the heat radiating plate 241 (the cooling air hits the heat radiating plate 241). Then, the heat conducted from the cooling pipe 250 to the heat radiating plate 241 is dissipated from the heat radiating plate 241. The heat conducted from the cooling pipe 250 is also dissipated from the duct portion rear surface 35 (the duct portion rear surface 35 which is not a component of the opening edge 40) where the cooling air does not directly hit.

(Modification of opening edge)
FIG. 5B shows a shroud 201 provided with a heat radiating plate 261 of a modification. The cylindrical opening edge 40 shown in FIG. 2 (a) could be transformed into a bell mouth-like opening edge 60 shown in FIG. 2 (b). Similarly, the heat radiating plate 241 of the cylindrical opening edge 40 shown in FIG. 5A can be transformed into the heat radiating plate 261 of the bell mouth-shaped opening edge 60 shown in FIG. 5B. That is, the cooling pipe 270 is provided in a part of the opening edge 60, and the portion of the opening edge 60 where the cooling pipe 270 is not provided is the heat radiating plate 261.

(Other variations of the opening edge)
The position of the heat sink 241 at the opening edge 40 shown in FIG. For example, the opening edge front portion 40f may be the heat radiating plate 241 and the opening edge rear portion 40r may be provided with the cooling pipe 250. Further, for example, the heat radiating plate 241 may be provided in the opening edge front part 40f and the opening edge rear part 40r, and the cooling pipe 250 may be provided therebetween. Similarly, the position of the heat radiating plate 261 at the opening edge 60 shown in FIG.

(Effect 2)
As shown in FIG. 5A, the opening edge 40 of the shroud 201 includes a heat radiating plate 241. Therefore, the heat of the cooling medium passing through the cooling pipe 250 is dissipated from the heat radiating plate 241. Therefore, the cooling medium passing through the cooling pipe 250 is more easily cooled.

(Third embodiment)
A shroud 301 of the third embodiment will be described with reference to FIGS. 6 and 7. FIG. 7 is a view taken in the direction of arrow F7 shown in FIG. A shroud 201 shown in FIG. 5A includes a heat radiating plate 241 in a portion of the opening edge 40 where the cooling pipe 250 is not provided. A shroud 301 shown in FIG. 6A includes a resonance silencer 355 in a portion (space) of the duct portion 30 where the cooling pipe 250 is not provided. Hereinafter, the difference will be further described.

  The resonance silencer 355 is a portion having an acoustic resonance structure in order to suppress noise. The resonance silencer 355 includes a box-shaped portion 355a, a hole 355b formed on the cooling fan 15 side (inside the shroud), and a cylindrical neck 355c extending from the hole 355b to the inside of the box-shaped portion 355a. Prepare. The resonant silencer 355 is provided integrally with the opening edge 40 (may be a separate body). The hole 355 b is formed in the opening edge 40. The resonant silencer 355 is provided integrally with the cooling pipe 250 (may be separate). For example, the inside of the cooling pipe 50 shown in FIG. 2A is divided at the center in the front-rear direction and the like, as shown in FIG. A container 355 is used.

  As shown in FIG. 7, the resonance silencer 355 is disposed along the circular duct portion 30 when viewed from the front-rear direction. The resonance silencer 355 is disposed so as to surround the outer periphery of the cooling fan 15. Note that the resonance silencer 355 may be disposed only in a part of the periphery of the cooling fan 15 instead of the entire periphery. For example, a plurality of resonance mufflers 355 (12 in FIG. 7) are provided.

  The resonance silencer 355 shown in FIG. 6A and FIG. 7 has a shape that can obtain a reduction effect with respect to the fan pitch sound (specific frequency peak) generated by the cooling fan 15. The frequency at which the reduction effect can be obtained is adjusted by adjusting the volume of the box-shaped portion 355a (back space), the cross-sectional areas of the hole portion 355b and the neck portion 355c, and the length of the neck portion 355c. The plurality of resonant silencers 355 may all have the same shape, or some or all of them may have different shapes.

(Modification of opening edge)
FIG. 6B shows a shroud 301 including a resonance type silencer 375 according to a modification. The cylindrical opening edge 40 shown in FIG. 5 (a) could be transformed into a bell mouth-like opening edge 60 shown in FIG. 5 (b). Similarly, the resonance silencer 355 of the duct portion 30 having the cylindrical opening edge 40 shown in FIG. 6A is a duct having the bell mouth-like opening edge 60 shown in FIG. 6B. The resonance muffler 375 of the unit 30 can be transformed.

(Other variations of the opening edge)
As in the case where the positions of the heat radiation plates 241 and 261 at the opening edges 40 and 60 shown in FIGS. 5A and 5B can be variously modified, in the duct portion 30 shown in FIGS. 6A and 6B. The positions of the resonance silencers 355 and 375 can be variously modified.

(Effect 3)
The duct portion 30 of the shroud 301 includes a resonance type silencer 355. Therefore, the noise in the cooling device 10 provided with the shroud 1 can be further reduced.

  As shown in FIG. 7, the resonance silencer 355 is disposed so as to surround the outer periphery of the cooling fan 15. Therefore, noise can be further reduced as compared with the case where the resonance silencer 355 is provided only in the vicinity of a part of the outer periphery of the cooling fan 15.

(Modification of the third embodiment)
A shroud 302 according to a modification of the third embodiment will be described with reference to FIG. The resonance silencer 355 shown in FIG. 7 may be transformed into a side branch resonance silencer 385 as shown in FIG. Hereinafter, this difference will be further described.

  The resonance silencer 385 includes a box-shaped portion 355a and a hole 355b, and does not include the neck 355c shown in FIG. The hole 355b is formed near the end of the box-shaped portion 355a. This “near end portion” means the vicinity of the end portion of the box-shaped portion 355a in the direction along the circumference of the circular duct portion 30 when viewed from the front-rear direction (referred to as “direction C”). The length L in the direction C inside the box-shaped portion 355a is adjusted according to the peak frequency of the fan pitch sound by the cooling fan 15 or the like. Specifically, for example, the length L is 1/4 of the wavelength of the sound at the peak frequency of the fan pitch sound. For example, a plurality of resonance mufflers 385 (six in FIG. 8) are provided.

  The shroud 302 including the resonance silencer 385 has the same effect as the shroud 301 including the resonance silencer 355 shown in FIG.

(Fourth embodiment)
A shroud 401 of the fourth embodiment will be described with reference to FIG. FIG. 9A corresponds to FIG. In FIG. 9A, the inside of the cooling pipe 50 is omitted. FIGS. 9B and 9C are schematic views showing the inside of the cooling pipe 50 shown in FIG. Unlike the shroud 1 shown in FIG. 3, the cooling pipe 50 of the shroud 401 shown in FIGS. 9A to 9C includes fin portions 451. Hereinafter, this difference will be further described.

  The fin portion 451 is provided inside the cooling pipe 50. The fin portion 451 includes a plurality of fin plates 451 a attached (fixed) to the inner surface of the cooling pipe 50. As shown in FIG. 9B, the fin portion 451 is provided over the entire cooling pipe 50. Moreover, as shown in FIG.9 (c), the fin part 451 is provided in a part (for example, center part of an up-down direction) of the cooling piping 50. As shown in FIG.

  The operation of the fin portion 451 shown in FIG. 9B or 9C is as follows. The fin part 451 makes the flow path of the cooling medium passing through the cooling pipe 50 into a labyrinth shape. The cooling medium flows through the cooling pipe 50 while being bent in a zigzag shape (S shape, Z shape), a spiral shape, etc. while being bent a plurality of times while hitting the fin plate 451a. Specifically, for example, the fin plates 451a are alternately arranged in the front-rear direction or the left-right direction (the direction on the horizontal plane orthogonal to the front-rear direction).

(Effect 4)
The cooling pipe 50 of the shroud 401 includes fin portions 451 inside. Therefore, the cooling medium passing through the cooling pipe 50 passes through the cooling pipe 50 while being in contact with the fin portion 451. Therefore, heat is further conducted from the cooling medium to the cooling pipe 50, and the heat of the cooling medium is more dissipated from the duct portion 30 (see FIG. 9A). Therefore, the cooling medium passing through the cooling pipe 50 is more easily cooled.

(Other variations)
The heat sink 241 and the like shown in FIG. 5, the resonance silencer 355 and the like shown in FIGS. 6 to 8, and the fin portion 451 shown in FIG. 9 have been described as separate embodiments. However, two or more of the above components may be combined.

1 Shroud (cooling fan shroud)
DESCRIPTION OF SYMBOLS 11 Heat exchanger 15 Cooling fan 15a Rotating shaft 20 Shroud main-body part 30 Duct part 40 Opening edge 50, 70 Cooling piping 241,261 Heat sink 355,375,385 Resonance type silencer 451 Fin part

Claims (4)

A shroud that covers between the periphery of the cooling fan that generates cooling air in the direction of the rotation axis and the heat exchanger,
A shroud body attached to the heat exchanger;
A duct portion provided inside the shroud main body portion and disposed around an outer periphery of the cooling fan;
The duct part is
An opening edge formed in a cylindrical shape with the rotation axis of the cooling fan as an axis, and forming an opening portion on which the cooling fan is disposed inside;
A cooling fan shroud comprising: a cooling pipe arranged to surround an outer periphery of the cooling fan and allowing a cooling medium to pass therethrough.   The shroud for a cooling fan according to claim 1, wherein the opening edge includes a heat radiating plate.   The cooling fan shroud according to claim 1, wherein the duct portion includes a resonance silencer.   The shroud for a cooling fan according to any one of claims 1 to 3, wherein the cooling pipe includes a fin portion therein.

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