EP4675051A1

EP4675051A1 - Work machine

Info

Publication number: EP4675051A1
Application number: EP24186188.9A
Authority: EP
Inventors: Antoine Gambier; Quentin COLIBERT
Original assignee: Yanmar Holdings Co Ltd
Current assignee: Yanmar Holdings Co Ltd
Priority date: 2024-07-03
Filing date: 2024-07-03
Publication date: 2026-01-07

Abstract

[Problem] To cool an entire heat exchanger while suppressing occurrence of uneven cooling which causes a difference in a degree of cooling depending on a location in a heat exchanger.

[Solution] A work machine (3) includes a fan (60) that blows air toward a heat exchanger (50). In the work machine, the fan is driven to cause air inside a machine room to pass through the heat exchanger and to be discharged to an outside of the machine room. The fan includes a hub (61) to which a plurality of propellers (65) are attached on an outer peripheral surface thereof. The hub has an end surface (64a) tapered toward the heat exchanger side.

Description

TECHNICAL FIELD

The present invention relates to a work machine such as a hydraulic excavator.

BACKGROUND ART

A discharge-type construction machine which blows air toward a heat exchanger from a fan and discharges the air having passed through the heat exchanger to the outside of a machine room has been known (see, for example, Patent Document 1).

PRIOR ART DOCUMENT

PATENT DOCUMENT

Patent Document 1: EP 1903149

SUMMARY OF INVENTION

TECHNICAL PROBLEM

The fan used in the discharge type has a hub fixed to a fan pulley. To an outer peripheral surface of the hub, a plurality of propellers are attached.
In the hub, if an end surface on a side facing the heat exchanger is formed to be flat, when the fan rotates, an air flow is less likely to occur between the end surface of the hub and the heat exchanger. Therefore, the air generated by driving of the fan is less likely to hit a region (central region) facing the hub in the heat exchanger. As a result, the central region of the heat exchanger is less likely to be cooled as compared with surrounding peripheral regions. That is, in the heat exchanger, uneven cooling occurs in which a degree of cooling varies depending on the location.
The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a work machine capable of cooling the entire heat exchanger while suppressing occurrence of uneven cooling in which the degree of cooling varies depending on the location in the heat exchanger.

SOLUTION TO PROBLEM

A work machine according to one aspect of the present invention is a work machine including a fan that blows air toward a heat exchanger and discharges air inside a machine room to an outside of the machine room through the heat exchanger by driving of the fan, in which the fan has a hub to which a plurality of propellers are attached on an outer peripheral surface thereof, and the hub has an end surface tapered toward the heat exchanger side.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the above configuration, it is possible to cool the entire heat exchanger while suppressing the occurrence of uneven cooling in which the degree of cooling varies depending on the location in the heat exchanger.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view illustrating a schematic configuration of a hydraulic excavator as an example of a work machine according to an embodiment of the present invention;
FIG. 2 is a perspective view illustrating an internal configuration of a machine room of the hydraulic excavator;
FIG. 3 is a front view illustrating the internal configuration of the machine room;
FIG. 4 is a perspective view of a shroud disposed inside the machine room;
FIG. 5 is a perspective view of a fan disposed inside the machine room;
FIG. 6 is a side view of the fan;
FIG. 7 is an exploded perspective view of the fan;
FIG. 8 is an exploded perspective view of the fan;
FIG. 9 is an explanatory view schematically illustrating a positional relation among a heat exchanger disposed inside the machine room, the fan, and the shroud;
FIG. 10 is an explanatory view schematically illustrating a flow of air when the heat exchanger is cooled by using the fan of a reference example;
FIG. 11 is an explanatory view schematically illustrating a flow of air when the heat exchanger is cooled by using the fan of an Embodiment of the present invention;
FIG. 12A is a side view schematically illustrating a variation of an end surface of a hub of the fan;
FIG. 12B is a side view schematically illustrating a variation of the end surface;
FIG. 13A is a side view schematically illustrating a variation of the end surface; and
FIG. 13B is a side view schematically illustrating a variation of the end surface.

DESCRIPTION OF EMBODIMENTS

An Embodiment of the present invention will be described below with reference to the drawings.

1. Work Machine

FIG. 1 is a side view illustrating a schematic configuration of a hydraulic excavator 1 as an example of a work machine according to this Embodiment. The hydraulic excavator 1 includes a lower traveling body 2, a work machine 3, and an upper revolving body 4. In this specification, the upper revolving body 4 may be referred to as a "machine body" in some cases.
Here, in this specification, each direction is described according to the following definition. The direction in which an operator (manipulator, driver) seated in a driver's seat 41a of the upper revolving body 4 faces forward is defined as front, and the opposite direction is defined as back. Therefore, in a state in which the upper revolving body 4 is not revolving with respect to the lower traveling body 2 (turning angle 0°), the front-back direction of the upper revolving body 4 coincides with the direction in which the lower traveling body 2 moves forward and backward. Moreover, the left side as viewed from the operator seated in the driver's seat 41a is referred to as "left" and the right side as "right", respectively. Further, a gravity direction perpendicular to the front-rear direction and the left-right direction is defined as an up-down direction, an upstream side in the gravity direction is defined as "up", and a downstream side is defined as "down". In the drawings, the hydraulic excavator 1 is illustrated in a state in which the upper revolving body 4 is not revolving with respect to the lower traveling body 2. Moreover, in the drawings, "F" represents a front side, "B" for a rear side, "L" for a left side, "R" for a right side, "U" for an upper side, and "D" for a lower side.
The lower traveling body 2 includes a pair of left and right crawlers 21 and a pair of left and right traveling motors 22. Each traveling motor 22 is a hydraulic motor. The left and right traveling motors 22 drive the left and right crawlers 21, respectively, so that the hydraulic excavator 1 can be moved forward and backward. The lower traveling body 2 further includes a blade 23 for a leveling work and a blade cylinder (not shown) for rotationally moving the blade 23 in the up-down direction.
The work machine 3 includes a boom 31, an arm 32, and a bucket 33. By driving the boom 31, the arm 32, and the bucket 33 independently, an excavation work of earth, sand and the like can be performed. Moreover, instead of the bucket 33, an attachment can be attached to the work machine as appropriate. For example, when a breaker is attached as the attachment, a crushing work or a demolishing work by a breaker can be performed.
The boom 31, the arm 32, and the bucket 33 are driven by a boom cylinder 31a, an arm cylinder 32a, and a bucket cylinder 33a, respectively. The boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a are constituted by hydraulic cylinders.
A base end part of the boom 31, that is, an end part of the boom 31 on a side opposite to a side connected to the arm 32 is swingably connected to a distal end portion 42a of a revolving frame 42 via a boom bracket 421. That is, the hydraulic excavator 1 of this Embodiment has a boom swing function in which the boom 31 swings to the left and right with the distal end portion 42a as a starting point. On the revolving frame 42, a swing cylinder 42b is provided. The swing cylinder 42b is constituted by a hydraulic cylinder and causes the boom 31 to swing by expanding / contracting.
The boom 31 has a shape bent forward at an obtuse angle, and is rotationally moved in the up-down direction by expansion / contraction of the boom cylinder 31a. The boom cylinder 31a is located closer to the front than the boom 31. The boom cylinder 31a has a base end part supported by the boom bracket 421, and a distal end part connected to a bent part of the boom 31 so as to be movable in an expansion / contraction manner. The arm 32 is connected capable of rotational movement at the distal end part of the boom 31. The arm 32 is rotationally moved in the up-down direction by expansion / contraction of the arm cylinder 32a. The arm cylinder 32a has a base end part supported by the boom 31, and a distal end part connected to a base end part of an arm 32 so as to be movable in the expansion / contraction manner. The bucket 33 is connected to the distal end part of the arm 32 via a link mechanism 34 and is rotationally moved in the up-down direction by the expansion and contraction of the bucket cylinder 33a. The bucket cylinder 33a has a base end part supported by the arm 32, and a distal end part connected to the link mechanism 34 so as to expand / contract.
The upper revolving body 4 is located above the lower traveling body 2 and is provided capable of revolving with respect to the lower traveling body 2. An operation portion 41, the revolving frame 42, a revolving motor 43, and a machine room 44 are disposed in the upper revolving body 4. The upper revolving body 4 is driven by the revolving motor 43, which is a hydraulic motor, to revolve via a revolving bearing (not illustrated). A plurality of hydraulic pumps (not shown) in addition to the engine 40, which provides power to various portions, are disposed inside the machine room 44.
Each hydraulic pump supplies hydraulic oil (pressure oil) to a hydraulic motor (for example, the left and right traveling motors 22 and the revolving motor 43) and a hydraulic cylinder via a hydraulic pipe. In addition to the above-described blade cylinder, the above-described hydraulic cylinder includes the boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a. The above-described hydraulic motors and hydraulic cylinders to which the hydraulic oil is supplied from an arbitrary hydraulic pump and driven are collectively called hydraulic actuators.
The operation portion 41 is provided on an upper part of the machine room 44. The driver's seat 41a is disposed in the operation portion 41. Various operation levers 41b are disposed in the periphery of the driver's seat 41a. When an operator is seated in the driver's seat 41a and operates the operation lever 41b, the predetermined hydraulic actuators are driven.
The operation portion 41 includes a canopy 45. The canopy 45 is erected on a rear upper part of the machine room 44 and covers at least the upper part of the driver's seat 41a. Note that a cabin may be provided instead of the canopy 45. The cabin has a door that is opened / closed when an operator gets on and off, and covers not only the upper part of the driver's seat 41a but also the front, rear, left, and right sides of the driver's seat 41a.
Side walls of the machine room 44 include a left hood (not shown), a right hood 44R, and a rear hood 44B. In the right hood 44R, a vent port 44P is provided. The vent port 44P is formed in a mesh shape. Air inside the machine room 44 is discharged to the outside through the vent port 44P by driving of a fan 60 (see FIG. 2 and the like), which will be described later, disposed inside the machine room 44.

2. Internal Configuration of Machine Room

2-1. Heat Exchanger

FIGS. 2 and 3 are a perspective view and a front view, respectively, illustrating a configuration of an interior of the machine room 44. Inside the machine room 44, a heat exchanger 50 is disposed in addition to the engine 40 described above. The heat exchanger 50 is disposed on the right side of the engine 40 inside the machine room 44. The above-described vent port 44P (see FIG. 1) is disposed further on the right side of the heat exchanger 50. The heat exchanger 50 includes a radiator 51 and an oil cooler 52.
The radiator 51 is a first heat exchanger connected to a water jacket of the engine 40 via a piping and cools a refrigerant passing through the above-described water jacket. The engine 40 can be cooled by cooling the above-described refrigerant by heat exchange in the radiator 51 and by supplying the refrigerant from the radiator 51 to the engine 40 (water jacket). The above-described refrigerant is, for example, cooling water.
The oil cooler 52 is a second heat exchanger connected to an oil passage circulating via the above-described hydraulic pump, the hydraulic actuator, and the like. The oil cooler 52 cools, through heat exchange, the hydraulic oil flowing in the above-described oil passage by driving of the hydraulic pump. In the example of FIG. 2, the oil cooler 52 is disposed side by side with the radiator 51 in the front-rear direction. Note that the oil cooler 52 may be disposed so as to at least partially overlap the radiator 51 when viewed from the left-right direction in FIG. 2.

2-2. Fan

As shown in FIGS. 2 and 3, the fan 60 is disposed between the engine 40 as a prime mover and the heat exchanger 50. Rotational power of a crankshaft of the engine 40 is transmitted to the fan 60 via a fan belt and a fan pulley. As a result, the fan 60 is rotationally driven. As described above, the hydraulic excavator 1 according to this Embodiment includes the engine 40 which generates power for driving the fan 60.
When the fan 60 is driven, the fan 60 blows air toward the heat exchanger 50. More specifically, when the fan 60 is driven, air is taken into the machine room 44 through, for example, an opening (not shown) provided in the revolving frame 42, and the taken-in air flows toward the heat exchanger 50. As a result, the heat exchanger 50 is cooled. In other words, the refrigerant (cooling water) flowing through the radiator 51 of the heat exchanger 50 is cooled, and the hydraulic oil flowing through the oil cooler 52 is cooled.
The air that has cooled the heat exchanger 50 passes through the gaps in the heat exchanger 50 or flows along the surfaces of the heat exchanger 50, is directed toward the vent port 44P (see FIG. 1), and is discharged from the vent port 44P to the outside of the machine room 44. As described above, the hydraulic excavator 1 as a work machine of this Embodiment includes the fan 60 disposed inside the machine room 44. The hydraulic excavator 1 discharges the air inside the machine room 44 to the outside of the machine room 44 through the heat exchanger 50 by driving of the fan 60. Note that details of the configuration of the fan 60 will be described later.

2-3. Shroud

A shroud 70 is disposed on the engine 40 side with respect to the heat exchanger 50. That is, the hydraulic excavator 1 includes the shroud 70 disposed between the engine 40 and the heat exchanger 50. The shroud 70 is a cover that covers the fan 60 and is also called a fan shroud.
FIG. 4 is a perspective view of the shroud 70 when viewed from the downstream side in the air blowing direction of the fan 60 (the side where the heat exchanger 50 is disposed). The shroud 70 has a first opening portion 71 and a second opening portion 72. The first opening portion 71 is provided on the upstream side in the air blowing direction with respect to the second opening portion 72 in the shroud 70. The first opening portion 71 is formed in a circular shape, for example, but the shape is not particularly limited. The fan 60 is disposed to enter the first opening portion 71. Therefore, the first opening portion 71 is formed in a shape larger than the fan 60 when viewed from the left-right direction of the hydraulic excavator 1.
The second opening portion 72 is provided on the downstream side in the air blowing direction, that is, on the heat exchanger 50 side in the shroud 70. The second opening portion 72 is formed in a square shape corresponding to an outer shape of the heat exchanger 50.
From the viewpoint of efficiently guiding of the air (cooling air) generated by the driving of the fan 60 to the heat exchanger 50 without diffusing the air to the surroundings and efficiently cooling of the heat exchanger 50, it is desirable to provide the above-described shroud 70 having the first opening portion 71 and the second opening portion 72 between the engine 40 and the heat exchanger 50.

2-4. Details of Fan

Subsequently, a configuration of the fan 60 will be described in detail. FIG. 5 is a perspective view of the above-described fan 60 when viewed from the heat exchanger 50 side. FIG. 6 is a side view of the fan 60. FIGS. 7 and 8 are perspective views of the fan 60 exploded and viewed from different directions. FIG. 9 is an explanatory view schematically illustrating a positional relation among the heat exchanger 50, the fan 60, and the shroud 70.
The fan 60 rotates around a rotation axis AX. In this Embodiment, the rotation axis AX extends in a direction passing through the heat exchanger 50, or specifically, in the left-right direction of the hydraulic excavator 1. The fan 60 includes a hub 61. The hub 61 includes an outer hub 62, an inner hub 63 (see FIG. 7), and a protruding portion 64.

2-4-1. Outer Hub

The outer hub 62 has a cylindrical portion 621. A central axis of the cylindrical portion 621 matches the rotation axis AX of the fan 60. A plurality of propellers 65 are attached to an outer peripheral surface 621a of the cylindrical portion 621. That is, the fan 60 has the hub 61 having the plurality of propellers 65 attached to the outer peripheral surface 621a thereof. In this Embodiment, five pieces of the propellers 65 are attached to the outer peripheral surface 621a. The number of propellers 65 is not limited to five, and can be arbitrarily set.
The outer hub 62 further has a bottom portion 622 (see FIG. 8). The bottom portion 622 is disposed inside the cylindrical portion 621 and on the side opposite to an insertion side of the inner hub 63. The bottom portion 622 and the cylindrical portion 621 are connected by a plurality of ribs 623 extending in the radial direction. Note that the radial direction refers to a direction perpendicular to the rotation axis AX. The plurality of ribs 623 are disposed in the circumferential direction of the rotation axis AX between the bottom portion 622 and the cylindrical portion 621.
The bottom portion 622 has a shaft insertion portion 622a and a hub fixing hole 622b provided. The shaft insertion portion 622a is a recessed portion formed at the center of the bottom portion 622. A drive shaft (not shown) of the fan 60 is inserted into and fixed to the shaft insertion portion 622a in an axial direction (a direction in which the rotation axis AX extends). Power from the engine 40 (see FIG. 1) is transmitted to the drive shaft via a fan belt or the like. The hub fixing holes 622b are formed at a plurality of positions (for example, four positions) around the shaft insertion portion 622a in the bottom portion 622. A bolt (not shown) for fixing the inner hub 63 is inserted into the hub fixing hole 622b.

2-4-2. Inner Hub

The inner hub 63 is formed in a columnar shape, and is fitted into the cylindrical portion 621 of the outer hub 62. The inner hub 63 is formed integrally with the protruding portion 64. In the inner hub 63, a through hole 63a penetrating in a direction parallel to the rotation axis AX is provided at a position corresponding to the hub fixing hole 622b of the outer hub 62. The through hole 63a is connected to a recessed portion 64P, which will be described later, provided in the protruding portion 64. The inner hub 63 is fixed to the outer hub 62 together with the protruding portion 64 by inserting the above-described bolt into the recessed portion 64P, passing the bolt through the through hole 63a and the hub fixing hole 622b, and fixing the bolt with a nut.
Note that the recessed portion 64P does not have to be connected to the through hole 63a. In this case, for example, a thread groove is formed in the inner peripheral surface of the through hole 63a, and a bolt is inserted from the hub fixing hole 622b side to be engaged with the thread groove in the inner surface of the through hole 63a, whereby the inner hub 63 can be fixed to the outer hub 62 together with the protruding portion 64.

2-4-3. Protruding Portion

The protruding portion 64 is disposed so as to protrude toward the heat exchanger 50 side with respect to the outer hub 62. The protruding portion has, for example, a conical shape and has an end surface 64a and a bottom surface portion 64b (see FIG. 8). The end surface 64a corresponds to a side surface of a conical shape which becomes a fan shape when being developed. The end surface 64a has a distal end portion 64T. The distal end portion 64T is a portion corresponding to the apex of the conical shape, and is located on the end surface 64a at a position closest to the heat exchanger 50 on the rotation axis AX. The bottom surface portion 64b is a portion corresponding to a bottom surface of the cone and is connected to the end surface 64a on the side opposite to the distal end portion 64T in the direction of the rotation axis AX. The inner hub 63 is connected to the bottom surface portion 64b.
A contact area (an area of a connection portion) of the bottom surface portion 64b with the inner hub 63 is smaller than an area of the entire bottom surface portion 64b. Therefore, when the inner hub 63 is fitted into the cylindrical portion 621 of the outer hub 62, the protruding portion 64 (in particular, the bottom surface portion 64b) comes into contact with the cylindrical portion 621 and does not enter the cylindrical portion 621.
Since the protruding portion 64 has a conical shape, a width (diameter) in the radial direction becomes narrower as the protruding portion 64 approaches the heat exchanger 50. That is, the protruding portion 64 has a shape tapered toward the heat exchanger 50 side. Therefore, the end surface 64a constituting the side surface of the protruding portion 64 also has a shape tapered toward the heat exchanger 50 side. That is, the hub 61 has the end surface 64a tapered toward the heat exchanger 50 side. In the end surface 64a, a plurality of the recessed portions 64P are provided, but details of the recessed portions 64P will be described later.
FIG. 10 is an explanatory view schematically illustrating a flow of air (cooling air) when the heat exchanger 50 is cooled using the fan 60A of the reference example. The fan 60A of the reference example corresponds to a configuration in which the protruding portion 64 is removed from the hub 61 in the fan 60 of this Embodiment. As the result of removing the protruding portion 64 from the hub 61, a surface 61S of the hub 61 facing the heat exchanger 50 is constituted by a flat surface perpendicular to the rotation axis AX. With this configuration, even when the fan 60A rotates, an air flow is unlikely to occur between the surface 61S of the hub 61 and the heat exchanger 50. Therefore, the air generated by the driving of the fan 60A is less likely to hit a central region CR facing the hub 61 in the heat exchanger 50. As a result, the central region CR of the heat exchanger 50 is less likely to be cooled as compared with a surrounding peripheral region PR, and uneven cooling occurs.
On the other hand, FIG. 11 is an explanatory view schematically illustrating a flow of air when the heat exchanger 50 is cooled using the fan 60 of this Embodiment. In the fan 60 of this Embodiment, the protruding portion 64 (end surface 64a) of the hub 61 has a tapered shape toward the heat exchanger 50 side. Therefore, when the fan 60 is driven, a flow of cooling air flowing along the end surface 64a of the hub 61 and toward the central region CR of the heat exchanger 50 can be created in the flow of the cooling air from the fan 60 toward the heat exchanger 50. As a result, the cooling air can be applied to both the central region CR of the heat exchanger 50 and the peripheral region PR outside the central region CR, whereby these regions can be cooled simultaneously. Therefore, it is possible to cool the entire heat exchanger 50 while suppressing uneven cooling in which a degree of cooling varies depending on a location in the heat exchanger 50.
In order to reliably cool the central region CR of the heat exchanger 50 by driving the fan 60, it is desirable to guide the cooling air to the central region CR facing the end surface 64a of the hub 61 in the heat exchanger 50 without being blocked by the other members. From this point of view, it is desirable that the end surface 64a of the hub 61 faces the heat exchanger 50 (without other members interposed therebetween).
In order to reliably realize the end surface 64a having a tapered shape on the heat exchanger 50 side, as shown in FIG. 9, it is desirable that the end surface 64a of the hub 61 has a shape in which the width in the radial direction (the diameter of the protruding portion 64) becomes narrower as the end surface approaches the heat exchanger 50. Moreover, when the end surface 64a of the hub 61 has the above-described shape, the cooling air flowing along the end surface 64a of the hub 61, when the fan 60 is driven, is drawn toward the center of the hub 61 (in a direction approaching the rotation axis AX) as the cooling air approaches the heat exchanger 50. Therefore, the flow of the cooling air guided to the central region CR of the heat exchanger 50 is reliably created.
In this Embodiment, as shown in FIG. 2, the heat exchanger 50 includes a radiator 51. Cooling water for cooling the engine 40 passes through the radiator 51. In the configuration including the engine 40, it is desirable to cool the engine 40 by applying cooling air to the heat exchanger 50 including the radiator 51 by driving of the fan 60 to reliably cool the radiator 51 and the cooling water. From this point of view, it is desirable that the fan 60 is disposed between the engine 40 and the heat exchanger 50 (particularly, the radiator 51).
In order to ensure that the cooling air flowing along the end surface 64a of the hub 61 is reliably applied to the central region CR of the heat exchanger 50, it is desirable to dispose the distal end portion 64T of the hub 61 as close as possible to the heat exchanger 50. For this purpose, it is desirable to dispose the shroud 70 covering the fan 60 as close as possible to the heat exchanger 50. On the other hand, as shown in FIG. 9, even in the case where the shroud 70 is disposed closest to the heat exchanger 50, a gap G serving as a margin in terms of assembly design is secured between the central region CR as well as the peripheral region PR against which the cooling air hits in the heat exchanger 50 and the second opening portion 72 of the shroud 70. In consideration of the gap G as above, it is desirable that the distal end portion 64T of the hub 61 is disposed as follows in order to reliably apply the cooling air to the central region CR of the heat exchanger 50. That is, it is desirable that the distal end portion 64T of the end surface 64a of the hub 61, which is closest to the heat exchanger 50, is disposed so as to protrude from the second opening portion 72 of the shroud 70 toward the heat exchanger 50 side.
In this Embodiment, as shown in FIGS. 5 to 7, the end surface 64a of the hub 61 has a conical shape with the distal end portion 64T closest to the heat exchanger 50 as an apex. With the configuration in which the end surface 64a has a conical shape, it is easy to create a flow of cooling air along the end surface 64a by driving of the fan 60 and to guide the cooling air to the central region CR of the heat exchanger 50.

2-4-4. Recessed Portion

As shown in FIGS. 5 to 7, the recessed portion 64P is provided in the end surface 64a of the hub 61. The recessed portion 64P extends in the direction of the rotation axis AX and is connected to the through hole 63a of the inner hub 63 but does not necessarily have to be connected thereto. That is, the recessed portion 64P may be a hole connected to the through hole 63a, or may be a concave portion closed on the through hole 63a side.
In the configuration in which the recessed portion 64P is provided in the end surface 64a, when the fan 60 is driven, a turbulent flow occurs in the cooling air flowing along the end surface 64a due to an opening 64P1 of the recessed portion 64P. Note that the opening 64P1 refers to an opening part of an inlet of the recessed portion 64P. Due to the turbulent flow described above, strong cooling air is less likely to locally hit only a part of the central region CR of the heat exchanger 50. That is, it is easy to cool the entire central region CR by applying the cooling air to the entire central region CR of the heat exchanger 50 or in other words, to reduce the uneven cooling of the central region CR.
In this Embodiment, a plurality of the recessed portions 64P are provided in the circumferential direction in the end surface 64a of the hub 61. The presence of the plurality of recessed portions 64P in the end surface 64a increases the effect of generating a turbulent flow by driving of the fan 60. Therefore, it becomes easier to cool the entire central region CR of the heat exchanger 50.
As shown in FIG. 6, the opening 64P1 of the recessed portion 64P has a shape extending toward the distal end portion 64T closest to the heat exchanger 50 in the end surface 64a. For example, as shown in FIG. 6, the opening 64P1 has an oval shape extending in the direction of the rotation axis AX when viewed from the radial direction. Note that the oval shape includes not only an egg shape but also an oblong shape and an elliptical shape.
Since the opening 64P1 of the recessed portion 64P has the above-described shape, when the fan 60 is driven, in the flow direction of the cooling air flowing toward the heat exchanger 50 along the end surface 64a of the hub 61, a range of the opening 64P1 in which a turbulent flow is generated in the cooling air is widened. This makes it easy to generate a turbulent flow in the cooling air.

2-4-5. Variation of Shape of Hub

The end surface 64a (protruding portion 64) of the hub 61 is not limited to the above-described conical shape as long as it has a shape tapered toward the heat exchanger 50 side. FIG. 12A and FIG. 12B are side views schematically illustrating a variation of the end surface 64a (protruding portion 64) of the hub 61. As shown in FIG. 12A, the end surface 64a of the hub 61 may have a truncated conical shape having a plane 64F facing the heat exchanger 50. Moreover, as shown in FIG. 12B, the end surface 64a of the hub 61 may have a shape having a curved surface 64R which is convex toward the heat exchanger 50 at the distal end.
FIG. 13A and FIG. 13B are side views schematically illustrating more variations of the end surface 64a of the hub 61. As shown in FIG. 13A, the entire end surface 64a of the hub 61 may have a shape having a curved surface that is convex toward the heat exchanger 50. Moreover, as shown in FIG. 13B, the end surface 64a of the hub 61 may have a shape having a curved surface that is concave toward the rotation axis AX side.

3. Supplement

Although the hydraulic excavator 1, which is a construction machine, has been described above as an example of a work machine, the work machine is not limited to the hydraulic excavator 1 and may be other construction machines such as a wheel loader, a compact truck loader and the like. Moreover, the work machine may be an agricultural machine such as a combine harvester, a tractor and the like.
The hydraulic excavator 1 as a work machine is configured to include the engine 40 (see FIG. 1) as a power motor but the power motor may be an electric motor.
The hydraulic excavator 1 as the work machine may have a configuration in which hydraulic equipment such as a hydraulic actuator (for example, a hydraulic motor or a hydraulic cylinder) and an actuator driven by electricity are used together. The actuators driven by electricity include an electric traveling motor, an electric cylinder, an electric revolving motor and the like, for example.

4. Supplementary Notes

The work machine described in this Embodiment can also be expressed as the following supplementary notes.
A work machine of Supplementary Note (1) is a work machine including

a fan that blows air toward a heat exchanger and discharging air inside a machine room to an outside of the machine room through the heat exchanger by driving of the fan, in which
the fan has a hub to which a plurality of propellers are attached on an outer peripheral surface thereof, and
the hub has an end surface tapered toward the heat exchanger side.

The work machine of Supplementary Note (2) is the work machine described in Supplementary Note (1), in which
the end surface of the hub faces the heat exchanger.
The work machine of Supplementary Note (3) is the work machine described in Supplementary Note (1) or (2), in which
the end surface of the hub has a width in a radial direction narrower as it approaches the heat exchanger.
The work machine of Supplementary Note (4) is the work machine described in any one of Supplementary Notes (1) to (3), in which
a recessed portion is provided in the end surface of the hub.
The work machine of Supplementary Note (5) is the work machine described in Supplementary Note (4), in which
the recessed portions are provided in plural in a circumferential direction in the end surface of the hub.
The work machine of Supplementary Note (6) is the work machine described in Supplementary Note (4) or (5), in which
an opening of the recessed portion has a shape extending toward a distal end portion in the end surface closest to the heat exchanger.
The work machine of Supplementary Note (7) is the work machine described in any one of Supplementary Notes (1) to (6), further including

an engine that generates power for driving the fan, in which
the heat exchanger includes a radiator through which cooling water for cooling the engine passes, and
the fan is disposed between the engine and the heat exchanger.

The work machine of Supplementary Note (8) is the work machine described in any one of Supplementary Notes (1) to (7), further including

a shroud disposed between the engine and the heat exchanger, in which
the shroud includes:
- a first opening portion through which the fan enters, and
- a second opening portion provided in the heat exchanger side.

The work machine of Supplementary Note (9) is the work machine described in Supplementary Note (8), in which
a distal end portion in the end surface of the hub closest to the heat exchanger is disposed so as to protrude from the second opening portion toward the heat exchanger side.
The work machine of Supplementary Note (10) is the work machine described in any one of Supplementary Notes (1) to (9) in which
the end surface of the hub has a conical shape with a distal end portion closest to the heat exchanger as an apex.
Although Embodiments of the present invention have been described above, a scope of the present invention is not limited thereto, and the present invention can be implemented by being expanded or changed within a range not departing from the gist of the invention.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a work machine such as a construction machine and an agricultural machine, for example.

REFERENCE SIGNS LIST

1 Hydraulic excavator (work machine)
40 Engine
44 Machine room
50 Heat exchanger
51 Radiator
60 Fan
61 Hub
64 Protruding portion
64P Recessed portion
64P 1 Opening
64a End surface
64T Distal end portion
65 Propeller
70 Shroud
71 First opening portion
72 Second opening portion
621a Outer peripheral surface
Ax Rotation axis

Claims

A work machine comprising a fan which blows air toward a heat exchanger, the work machine discharging air inside a machine room to an outside of the machine room through the heat exchanger by driving of the fan, wherein
the fan has a hub to which a plurality of propellers are attached on an outer peripheral surface thereof; and

the hub has an end surface tapered toward the heat exchanger side.
The work machine according to claim 1, wherein the end surface of the hub faces the heat exchanger.
The work machine according to claim 1 or 2, wherein the end surface of the hub has a width in a radial direction narrower as approaching the heat exchanger.
The work machine according to any one of claims 1 to 3, wherein a recessed portion is provided in the end surface of the hub.
The work machine according to claim 4, wherein the recessed portions are provided in plural in a circumferential direction in the end surface of the hub.
The work machine according to claim 4 or 5, wherein an opening of the recessed portion has a shape extending toward a distal end portion in the end surface closest to the heat exchanger.
The work machine according to any one of claims 1 to 6, further comprising an engine that generates power for driving the fan, wherein
the heat exchanger includes a radiator through which cooling water for cooling the engine passes; and

the fan is disposed between the engine and the heat exchanger.
The work machine according to any one of claims 1 to 7, further comprising a shroud disposed between the engine and the heat exchanger, wherein
the shroud includes:
a first opening portion through which the fan enters; and

a second opening portion provided on the heat exchanger side.
The work machine according to claim 8, wherein a distal end portion in the end surface of the hub closest to the heat exchanger is disposed and protrudes from the second opening portion toward the heat exchanger side.
The work machine according to any one of claims 1 to 9, wherein the end surface of the hub has a conical shape with a distal end portion closest to the heat exchanger as an apex.