JP2016148316A - Cooling fan structure for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling fan structure for an internal combustion engine that has a simple configuration but can effectively increase fan efficiency.SOLUTION: The cooling fan structure for an internal combustion engine includes a cooling fan 17 turned by power of a crankshaft of an engine in an integrated manner. The cooling fan 17 has multiple rotary vanes 24 disposed around a revolving shaft 26. Each of the multiple rotary vanes 24 has a front end side in the rotation direction thereof that is formed so as to be bent into a hook-shape in axial view of the revolving shaft 26. A hook-shaped opening part 30 is opened on a positive pressure side (+) in a rotation direction A of the cooling fan 17.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a cooling fan structure of an internal combustion engine suitable for an engine in a vehicle such as a motorcycle, particularly a forced air cooling type engine.

  In an internal combustion engine mounted on a so-called motorcycle such as a scooter, a cylinder and a cylinder head, which are radiating portions, are covered with a shroud, and cooling air is introduced into the shroud with a cooling fan provided at the shaft end of the crankshaft. There is a cooling structure in which the cooling air is blown around the cylinder head. In addition to the motorcycle of this example, various forced air-cooling type cooling devices using a centrifugal cooling fan are used, including home appliances and the like.

  In addition, in the thing of patent document 1, for example, this is an application example of an air conditioner or the like. It is provided with a plurality of blade portions provided at intervals, and the blade portion is formed by bending the center line of the blade cross-sectional shape extending between the front edge portion and the rear edge portion at a plurality of locations, and is ahead of the rear edge portion. It has a bent portion arranged in a region near the edge. And in the direction which a bending part connects a front edge part and a rear edge part, it is going to aim at the improvement of ventilation capability with the centrifugal fan formed so that a folding direction may become an opposite direction alternately.

Japanese Patent No. 4761323

  In conventional vehicle cooling systems, the cooling air around the cylinder head is cooled by cooling air introduced into the shroud by a cooling fan. On the other hand, the air blowing efficiency of the cooling fan significantly affects the fuel consumption etc. in relation to its driving energy. It is a very important factor. In the past, there was essentially no consideration for the efficiency of the cooling fan, especially in relation to the shape of the cooling fan itself, and it was limited to adjusting the exit angle or blade height of the rotor blade or rotor blade of the cooling fan. Was the actual situation.

  In addition, in the centrifugal fan according to Patent Document 1, since the rotating blades or the rotating blades are bent at the bent portion, there is a problem that the passage area of the inflowing air becomes narrow and the amount of air blown has to be reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling fan structure for an internal combustion engine that can effectively improve fan efficiency while having a simple configuration.

  A cooling fan structure for an internal combustion engine according to the present invention is a cooling fan structure for an internal combustion engine having a cooling fan that rotates integrally with the power of a crankshaft of the engine, and the cooling fans are arranged around a rotating shaft. The rotary blades are characterized in that each rotary blade is bent in a hook shape when viewed in the axial direction of the rotary shaft.

  In the cooling fan structure for an internal combustion engine according to the present invention, the hook-shaped opening is formed on the positive pressure side in the rotation direction of the cooling fan.

  The cooling fan structure for an internal combustion engine according to the present invention has an arc portion that forms the hook shape, and the arc portion is disposed so as to face the rotation axis of the cooling fan.

  Also, in the cooling fan structure for an internal combustion engine according to the present invention, the rotary blades are connected to each other via a reinforcing ring at the tip end side of the rotating shaft, and the hook-shaped opening is formed by the reinforcing ring. It protrudes to the inner side of the part.

  Further, in the cooling fan structure of the internal combustion engine according to the present invention, each of the rotary blades is provided with a rib on the negative pressure side opposite to the opening of the hook type when viewed from the axial direction of the rotary shaft. A recess is provided up to the rear end in the rotation direction.

  Further, in the cooling fan structure of the internal combustion engine according to the present invention, the rotating blades are connected to each other via a base portion on the base end side of the rotating shaft, and the front end side in the rotation direction is connected to the base portion. The rear end side in the rotation direction is connected to the reinforcing annular portion.

  According to the present invention, it is possible to effectively improve the fan efficiency and to simplify the apparatus and reduce the weight by changing only the shape of the rotary blade.

1 is a side view showing an overall configuration of a motorcycle according to the present invention. 1 is a front perspective view showing a configuration example of a power unit in a motorcycle according to the present invention. It is a right side view showing a configuration example of a power unit in the motorcycle according to the present invention. 1 is a plan sectional view showing a configuration example of a power unit in a motorcycle according to the present invention. It is a right perspective view of the cooling fan which concerns on the cooling fan structure of the internal combustion engine of this invention. It is a left perspective view of the cooling fan which concerns on the cooling fan structure of the internal combustion engine of this invention. It is a right front view of the cooling fan according to the cooling fan structure of the internal combustion engine of the present invention. It is a longitudinal cross-sectional view of FIG. 7A which passes along the rotary blade of the cooling fan which concerns on the cooling fan structure of the internal combustion engine of this invention. It is a left front view of the cooling fan which concerns on the cooling fan structure of the internal combustion engine of this invention. It is a longitudinal cross-sectional view of FIG. 8A which passes along the rotary blade of the cooling fan which concerns on the cooling fan structure of the internal combustion engine of this invention.

Hereinafter, preferred embodiments of a cooling fan structure for an internal combustion engine according to the present invention will be described with reference to the drawings.
FIG. 1 is a side view of a motorcycle as a vehicle according to the present invention. First, the overall configuration of the motorcycle will be described with reference to FIG. In the drawings used in the following description, including FIG. 1, the front of the vehicle is indicated by an arrow Fr, the rear of the vehicle is indicated by an arrow Rr, and the lateral right side of the vehicle is indicated by an arrow R as necessary. The left side is indicated by an arrow L.

  The vehicle 100 has a vehicle body skeleton formed by a plurality of vehicle body frames made of steel or aluminum alloy, and is configured through various components mounted on the vehicle body frame. Although not shown in detail, the down tube, which is a part of the vehicle body frame, has a front end coupled to the steering head pipe, extends substantially downward from the steering head pipe, and has an under frame near its lower end. 101 is connected. The under frame 101 extends substantially rearward. A pair of left and right rear frames 102 as a part of the vehicle body frame is coupled to the rear side of the under frame 101, and each of the pair extends generally inclining rearward and upward.

  Further, the steering head pipe supports the front fork 103 so that the front fork 103 can be rotated in the left-right direction. A handlebar 104 is fixed above the front fork 103 and a front wheel 105 is rotatably supported on the lower end side. . The front wheel 105 is equipped with a brake disk 106 that rotates integrally therewith.

  Further, a bracket for supporting the power unit 10 including the engine 11 (see FIG. 2 and the like in detail) is attached to the rear end of the under frame 101, and a swing shaft 108 is provided via a stay 107 provided on the bracket. A swing type power unit 10 is supported so as to be swingable in the vertical direction. The power unit 10 is a unit that includes a cylinder assembly (described later) of the engine 11 and a power transmission device that includes a continuously variable transmission using a crankcase and a belt / pulley. The rear wheel 109 is rotatably supported by a power transmission device on the rear side of the vehicle. The axle side of the rear wheel 109 and the rear frame 102 are connected by a shock absorber 110, and the power unit 10 as a whole functions as a swing arm.

  As shown in FIG. 1, a seat 111 for a rider to sit on is installed above the power unit 10, and a step board 112 on which the rider seated on the seat 111 places his feet above the underframe 101, Supported by a step frame. The step board 112 is formed integrally with the leg frame cover 113 that constitutes the exterior of the vehicle. Further, between the power unit 10 and the seat 111, there is a luggage box configured as a storage space for articles and the like opened and closed by the seat 111.

  As a vehicle exterior, various vehicle body covers are supported and attached to appropriate positions such as a vehicle body frame. The front leg shield 114 covers the front side of the vehicle and is mounted with a winker or the like, and is continuous with the above-described step board 112. The rear frame cover 115 covers the lower side of the seat 111 or the rear side of the vehicle, and a winker and a brake lamp are mounted. Upper portions of the front wheel 105 and the rear wheel 109 are covered with a front fender 116 and a rear fender 117, respectively.

  Next, the power unit 10 will be described with reference to FIGS. 2 is a front perspective view of the power unit 10, FIG. 3 is a right side view of the power unit 10 with the shroud removed, and FIG. 4 is a plan sectional view. The basic configuration of the power unit 10 includes an air-cooled four-cycle single-cylinder engine 11, which is, for example, an SOHC engine in this example. The engine 11 includes a crankcase 13 that rotatably supports and accommodates a crankshaft 12 (abbreviated by a one-dot chain line in FIG. 2) that is horizontally arranged in the left-right direction, and a cylinder 14 and a cylinder sequentially forward with respect to the crankcase 13. The head 15 and the cylinder head cover 16 are coupled, and the cylinder axis Z is set in a substantially horizontal direction. In this case, the cylinder axis Z of the cylinder 14 is tilted considerably forward, that is, approximately in the form of substantially horizontal so that the cylinder head 15 side is appropriately raised.

  A centrifugal cooling fan 17 for cooling the engine is attached to the shaft end of the crankshaft 12, and this cooling fan 17 generates cooling air as will be described later. In this case, the cylinder 14, the cylinder head 15, and the cooling fan 17 are covered with the shroud 18 so as to form a predetermined cooling air flow path. Therefore, the portions of the cylinder 14 and the cylinder head 15 that are covered with the shroud 18 do not substantially appear in appearance as shown in FIG.

  The power unit 10 further includes a power transmission 19 that is integrally coupled to the crankcase 13, and the power transmission 19 includes a continuously variable transmission that uses a belt, a pulley, and the like. In this example, as shown in FIG. 4, the crankcase 13 is divided into left and right parts (crankcase 13R, crankcase 13L), and the casing 20 of the power transmission device 19 is coupled to the crankcase 13L. A continuously variable transmission including a belt, a pulley, and the like is disposed in the casing 20, and the crankshaft 12 and the axle of the rear wheel 109 are connected by a power transmission device 19.

  Although not shown in FIG. 2 and the like, an intake system including an air cleaner and the like is arranged on the upper surface side of the power transmission device 19. In this intake system, an intake hose, a throttle body, an intake pipe (intake pipe), and the like are sequentially connected in front of the air cleaner. This intake pipe communicates with an intake port (intake port) 21 of the cylinder head 15 shown in FIG. 2, and is cleaned from the air cleaner to the intake port 21 of the cylinder head 15 through an intake passage constituted by these members. Supplied air is supplied. In addition, a fuel injection device is mounted at an appropriate position along the intake pipe so as to inject fuel toward the intake port.

  On the other hand, in the exhaust system for exhausting exhaust gas from the engine 11, an exhaust port (exhaust port) is provided on the lower surface side of the cylinder head 15 in this example. An exhaust pipe (exhaust pipe) is coupled to the exhaust port. The exhaust pipe temporarily extends to the right from the connection portion with the exhaust port, then curves backward, and further extends backward near the lower portion of the cooling fan 17. The exhaust pipe is further connected to a muffler 22 (see FIG. 1) at the rear of the vehicle. The combustion gas generated in the engine 11 passes through the exhaust pipe from the exhaust port and is finally exhausted from the muffler 22 as exhaust gas.

  Next, in the cooling system that cools the power unit 10, the cylinder 14, the cylinder head 15, and the cooling fan 17 are covered with the shroud 18 as described above (see FIGS. 2 and 4). That is, the cylinder 14 and the cylinder head 15 including the cooling fan 17 are surrounded by the shroud 18 as shown in FIG. The shroud 18 is formed of a synthetic resin or a plastic material, and the crankcase 13 or the cylinder block is fitted with a fixing means such as a screw in a suitable place on the outer wall of the cylinder case 13 or the cylinder block. It is fixed so that it does not occur. The top of each cooling fin 23 (see FIGS. 3 and 4) projecting from the outer peripheral surface of the cylinder 14 and the like and the inner surface of the shroud 18 are spaced so as to form a fixed gap.

  Here, the crankshaft 12 is abbreviated by a one-dot chain line in FIG. 4, but is rotatably supported by the crankcase 13R and the crankcase 13L via a bearing. In this example, as shown in FIG. 4, a cooling fan 17 is integrally coupled to the right end of the crankshaft 12, and the cooling fan 17 is centered on the crankshaft 12 as shown in FIG. A plurality of rotating blades 24 are disposed along the circumferential direction. The details of the cooling fan 17 including the rotary blades 24 and the like will be described later. The cooling fan 17 is coupled to rotate integrally with the crankshaft 12. An alternator 25 (shown schematically by a two-dot chain line in FIG. 4) is disposed adjacent to the inside of the engine 11 of the cooling fan 17, and a rotor (not shown) of the alternator 25 is coaxially fixed to the crankshaft 12 so that the crank It rotates integrally with the shaft 12.

  With respect to the shape of the shroud 18 and the like, an air introduction opening 18 a concentric with the rotating shaft (crankshaft 12) of the cooling fan 17 is opened on the right side of the shroud 18 corresponding to the cooling fan 17. The shroud 18 has a side wall 18b (right side wall) extending forward from the air introduction opening 18a to a portion corresponding to the right side surface of the cylinder head 15. As shown in FIG. 4, the side wall 18b of the shroud 18 has a lateral width that narrows from the air introduction opening 18a toward the tip, that is, the side wall 18b faces forward in the plan view of FIG. A curve is formed with a large curvature radius so as to approach the cylinder axis Z.

The basic operation and the like in the cooling system having the cooling structure having the above configuration will be described briefly. When the engine 11 is started and the crankshaft 12 rotates, the rotation of the cooling fan 17 attached to the shaft end side of the crankshaft 12 rotates. The blade | wing 24 rotates like the arrow A of FIG. As a result, the air around the cooling fan 17 is entrained and introduced into the shroud 18 from the air introduction opening 18a as indicated by the arrow _AIN in FIG. Mainstream of the cooling air flows to the cylinder head 15 along the inner wall of the shroud 18 as shown by an arrow A _1. Thereafter, the cooling air branches upward and downward, and the branched cooling air passes through the periphery of the cylinder 14 and the cylinder head 15 and is discharged from the cooling air exhaust port.

  In the cooling fan structure of the internal combustion engine of the present invention, the cylinder 14 and the cylinder head 15 as the heat radiating section are covered with the shroud 18 as described above, and the cooling air is shroud by the cooling fan 17 that rotates integrally with the power of the crankshaft 12. 18 and is forced to cool around the cylinder 14 and the cylinder head 15.

  In the present invention, in particular, as shown in FIGS. 5 and 6, the cooling fan 17 has a plurality of rotating blades 24 disposed around the rotating shaft 26. 5 is a perspective view of the cooling fan 17 viewed from the right side, and FIG. 6 is a perspective view of the cooling fan 17 viewed from the left side (crankshaft 12 side). Each rotary blade 24 is formed in a hook-like shape on the front end side in the rotational direction (FIG. 5, arrow A) as viewed in the axial direction of the rotary shaft 26. Here, the rotating shaft 26 of the cooling fan 17 is abbreviated by an alternate long and short dash line in FIG. 5 and the like, but is set coaxially on the shaft end portion on the right side of the crankshaft 12.

  The cooling fan 17 includes a plurality of rotating blades 24 arranged at predetermined pitch intervals along the rotation direction, a base portion 27 supported on the right shaft end side of the crankshaft 12, and the rotating blades 24. The base portion 27 includes a reinforcing annular portion 28 disposed on the opposite side of the rotating shaft 26 in the axial direction, and these can be integrally formed of a synthetic resin material. The base portion 27 has a substantially disk shape centered on the rotating shaft 26. As a specific mounting structure, for example, a plurality of mounting boss portions 29 are attached to a bracket fixed to the right shaft end portion of the crankshaft 12. The base portion 27 rotates synchronously with the crankshaft 12. The reinforcing annular portion 28 has a ring shape or a donut shape.

  FIG. 7A is a front view of the cooling fan 17 as viewed from the right side, and FIG. 7B is a longitudinal sectional view through the rotary blade 24. 8A is a front view of the cooling fan 17 as viewed from the left, and FIG. 8B is a longitudinal sectional view through the rotary blade 24. Referring also to these drawings, the base portion 27 and the reinforcing annular portion 28 are arranged concentrically, and the outer diameter of the base portion 27 substantially matches the inner diameter of the reinforcing annular portion 28. An opening 30 is provided at a portion of the rotary blade 24 that is bent in a hook shape, that is, at the front end side thereof. The opening 30 of each rotary blade 24 is a positive pressure side in the rotation direction of the cooling fan 17 (illustrated for a specific rotary blade 24 in FIG. 7B, the positive pressure side is indicated by (+), and the negative pressure side is indicated by (−). Is the same for all rotating blades 24).

  In addition, an arc portion 31 that forms a hook shape is formed on the front end side of each rotary blade 24, and the arc portion 31 is disposed so as to face the rotation shaft 26 of the cooling fan 17. The arc portion 31 is located at the front end in the rotation direction of the rotary blade 24 and is formed to face the rotation shaft 26.

  Further, as shown in FIGS. 5 and 6, each rotary blade 24 has a width or a height in the direction of the rotary shaft 26, and a reinforcing annular portion 28 is provided on the tip side (right side) of the rotary shaft 26. Connected to each other. In this case, the hook-shaped opening 30 protrudes to the inner side of the reinforcing annular portion 28. In other words, the front end side of the rotary blade 24 in which the opening 30 is formed is not directly connected to the reinforcing annular portion 28 and is exposed to the inside of the reinforcing annular portion 28 as shown in FIG. 7A.

  On the other hand, the rotating blades 24 are connected to each other via a base portion 27 on the base end side (left side) of the rotating shaft 26, and the front end side in the rotation direction is connected to the base portion 27. In this case, as shown in FIGS. 7B and 8B, the rear end side in the rotation direction of the rotary blade 24 is curved and extended in a generally arcuate shape from the opening 30 toward the outer peripheral side of the reinforcing annular portion 28. , Connected to the reinforcing annular portion 28. More specifically, the rear end side in the rotation direction of the rotary blade 24 may be formed so as to fly in a direction opposite to the rotation direction with respect to the radial direction with respect to the rotation axis 26 passing through the approximate center of the arc portion 31. In addition, it contributes to the rectification | straightening effect | action with respect to the air flow introduce | transduced as a shape effect of this rotary blade 24. FIG.

  Further, each rotary blade 24 is provided with a rib 32 on the negative pressure side (indicated by (−) in FIG. 7B) opposite to the hook-shaped opening 30 as viewed in the axial direction of the rotary shaft 26. In this example, one or a plurality of the above-described arcuate curved portions on the rear end side in the rotation direction of the rotary blades 24 have two ribs 32 in this example, and the rotation direction from the hook-shaped portion on the negative pressure side of each rotary blade 24. A recess 33 is formed by these ribs 32 until the rear end. In this case, as shown in FIG. 7B and FIG. 8B, the rib 32 may be formed so as to intersect the rotary blade 24 (at the rear end side in the rotation direction) at an acute angle. In addition, it contributes to the rectification effect | action with respect to the air flow introduce | transduced as a shape effect of this rotary blade 24 and the rib 32. FIG. About these rotary blades 24, ribs 32, recesses 33, etc., specific symbols are attached in each figure, but the same applies to all rotary blades 24.

  The internal combustion engine cooling fan structure of the present invention is configured as described above. Next, its main effects and the like will be described. First, when the rotating blade 24 of the cooling fan 17 rotates using the crankshaft 12 as a driving source (for example, arrow A in FIG. 3), the air around the cooling fan 17 is drawn into the shroud 18 from the air introduction opening 18a. be introduced. At that time, the wind flowing from the front end side of the rotary blade 24 to the positive pressure side (FIG. 7B, (+) region) is rectified by the small vortex generated in the hook-shaped opening 30, thereby reducing the air resistance.

  In this case, the arc portion 31 is positioned at the front end in the rotation direction of the rotary blade 24 and is disposed so as to face the rotation shaft 26 of the cooling fan 17. Thus, by providing the large circular arc portion 31 on the front end side in the rotation direction of the rotary blade 24, the air resistance when the rotary blade 24 cuts the wind is reduced. And since the air resistance of the rotary blades 24 is reduced, so-called mechanical loss (mechanical loss) is reduced, and the operating efficiency (fan efficiency) of the cooling fan 17 is increased. it can.

  Further, a hook-shaped opening 30 of the cooling fan 17 is provided so as to project to the inner side of the reinforcing annular portion 28. Since the hook-shaped portion of the rotary blade 24 protrudes inward from the reinforcing annular portion 28 with respect to the air introduced into the shroud 18 from the air introducing opening 18a, the reinforcing annular portion 28 itself Without being obstructed, it is possible to efficiently collect the wind of air that is introduced.

  Furthermore, a rib 32 is provided on the negative pressure side (FIG. 7B, (−) region) opposite to the hook-shaped opening 30, and a recess 33 is provided from the hook shape to the rear end in the rotation direction. Speaking of the rotary blade 24, by providing the concave portion 33 on the back side and generating a small vortex in the concave portion 33, rectification is achieved while suppressing separation of the introduced wind, and air resistance is reduced. Also in this case, the air resistance of the rotary blade 24 is reduced, so that the operating efficiency of the cooling fan 17 can be increased.

  As described above, the rotating blade 24 has a hook-shaped opening 30 with the front end side in the rotation direction connected to the base portion 27 and the rear end side in the rotation direction connected to the reinforcing annular portion 28. Substantial change in the shape of the rotary blade 24 without adding additional parts, etc., but with a simple configuration, the air flow rate as the cooling fan 17 is the same as the conventional product, that is, the air flow rate is equal to or greater than that. Therefore, the number of the rotary blades 24 can be substantially reduced. In this way, the air blowing performance of the cooling fan 17 can be secured and maintained, and the weight of the device can be reduced. At that time, the number of the rotary blades 24 is reduced, so that the passage area of the air wind introduced is reduced. The air resistance is reduced at this point.

As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
The number of the rotary blades 24 and the ribs 32 provided on the rotary blades 24 in the above embodiment is not limited to the illustrated example, and can be increased or decreased as necessary.

DESCRIPTION OF SYMBOLS 10 Power unit, 11 Engine, 12 Crankshaft, 13 Crankcase, 14 Cylinder, 15 Cylinder head, 16 Cylinder head cover, 17 Centrifugal cooling fan, 18 shroud, 19 Power transmission device, 20 Casing, 21 Intake port, 23 Cooling fin, 24 Rotating blades, 25 Alternator, 26 Rotating shaft, 27 Base part, 28 Reinforcement ring part, 29 Mounting boss part, 30 Opening part, 31 Arc part, 32 Rib, 33 Recessed part, 100 Vehicle.

Claims (6)

A cooling fan structure for an internal combustion engine comprising a cooling fan that rotates integrally with the power of the crankshaft of the engine,
The cooling fan has a plurality of rotating blades disposed around a rotating shaft, and each rotating blade has a hook-like curved shape at the front end in the rotating direction when viewed in the axial direction of the rotating shaft. A cooling fan structure for an internal combustion engine.   2. The cooling fan structure for an internal combustion engine according to claim 1, wherein the hook-shaped opening is formed on a positive pressure side in a rotation direction of the cooling fan.   The cooling fan structure for an internal combustion engine according to claim 2, further comprising an arc portion that forms the hook shape, the arc portion being arranged to face the rotation shaft of the cooling fan.   The rotating blades are connected to each other via a reinforcing ring at the tip end side of the rotating shaft, and the hook-shaped opening protrudes to the inner side of the reinforcing ring. A cooling fan structure for an internal combustion engine according to claim 2 or 3.   Each of the rotating blades is provided with a rib on the negative pressure side opposite to the opening of the hook shape when viewed in the axial direction of the rotating shaft, and a recess is provided from the hook shape to the rear end in the rotation direction. The cooling fan structure for an internal combustion engine according to claim 4.   The rotating blades are connected to each other via a base portion on the base end side of the rotating shaft, the front end side in the rotating direction is connected to the base portion, and the rear end side in the rotating direction is connected to the reinforcing annular portion. 6. A cooling fan structure for an internal combustion engine according to claim 4, wherein the cooling fan structure is provided.

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