JPH057039Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to an engine cooling system for a model helicopter operated by radio control or the like, and particularly relates to a cooling system that generates cooling air for forced air cooling of the engine. The present invention relates to an engine cooling device equipped with a fan.

(Prior Art) In a model helicopter operated by radio control or the like, the output rotation of a model engine is transmitted to a main rotor and a tail rotor via a clutch and a reduction mechanism, and as these rotors rotate, It is designed to fly in the air in a stable position.

In that case, it is necessary to cool the engine, and in model engines, a forced air cooling method using a cooling fan is often adopted as the cooling method.

In a typical conventional engine cooling system using such a forced air cooling method, a centrifugal fan is directly attached to the crankshaft of the engine, and cooling air is generated by the centrifugal fan. In such a device, the cooling air flows out radially in a direction perpendicular to the axial direction of the crankshaft. In that case, the cylinder head of the engine is also located perpendicular to the axial direction of the crankshaft, but since the position of the centrifugal fan and the position of the cylinder head are relatively shifted in the longitudinal direction of the crankshaft, cooling air is does not flow to the cylinder head. Therefore, a cooling cover is usually provided to enclose the centrifugal fan, and the cover guides cooling air to the cylinder head.

(Problems to be Solved by the Invention) However, in such an engine cooling system, the air delivery efficiency of the centrifugal fan is not very high, so a large amount of air cannot be sent to the cylinder head. Moreover, since the flow of cooling air is bent by the cooling cover, turbulence occurs in the flow, and a portion of the cooling air escapes to the outside.

As a result, the flow rate of cooling air flowing into the cylinder head is small compared to the rotational speed of the fan.

Therefore, the engine cannot be effectively cooled, and the power loss of the engine becomes extremely large.

Furthermore, in the case where the cooling air is guided to the cylinder head by a cooling cover, the cooling air comes into contact with the cylinder head only from one direction.
Therefore, the cylinder head is cooled only on one side and cannot be cooled uniformly, resulting in uneven cooling effect.

Moreover, in the case where the fan is simply provided on the crankshaft, a cooling cover is required to guide the cooling air to the cylinder head, which increases the number of parts.

The present invention was devised in view of such problems, and its purpose is to enable the engine to be effectively cooled while reducing the power loss of the engine as much as possible.

Another object of the present invention is to reduce the number of parts.

(Means for solving the problem) In order to achieve this object, the present invention uses an axial flow fan as the cooling fan. The engine is supported within the cylindrical casing by aligning the center axis of the cylinder with the center axis of the casing, and the axial fan can be rotated by aligning the axis of the rotating shaft with the center axis of the casing. The axial fan is rotated by the power of the engine via a power transmission mechanism that supports the fan and transmits the rotation of the engine's crankshaft while changing the direction almost at right angles.

(Operation) With this configuration, the cylinder of the engine and the rotating shaft of the axial flow fan are arranged in series on a straight line.

In that case, the rotational axis of the axial fan and the crankshaft are perpendicular to each other, but the rotation of the crankshaft is transmitted to the rotational axis of the axial fan by being redirected by the power transmission mechanism.
Therefore, the axial fan can be rotated by the engine, and cooling air can be generated by rotation of the axial fan.

At this time, since the cooling air is guided by the cylindrical casing, it flows approximately linearly. This allows all of the cooling air to contact the engine.

As a result, the engine is effectively cooled.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

The figures show an embodiment of the engine cooling system for a model helicopter according to the present invention, and FIG. 1 is a front view of the engine cooling system, and FIG.
A partial vertical sectional view taken along the - line in the figure.
FIG. 3 is a sectional view taken along the - line in the figure.

As shown in FIGS. 1 to 3, the casing 1 is formed in a cylindrical shape, and its central axis extends in the longitudinal direction of the fuselage. A portion near the front end of the casing 1 is a reduced diameter portion 1a, and the front end portion of the casing 1 is formed so as to continue outward from the reduced diameter portion 1a and widen toward the end.

An engine 2 is disposed near the front end of the internal space of the casing 1. In this engine 2, the cylinder head 2a has an opening 1b on the front end side of the casing 1.
cylinder 2.
It is attached to the inner wall 1c of the casing 1 so that the center axis of the casing 1b coincides with the center axis of the casing 1. In this case, the portions of the cylinder head 2a and the cylinder 2b where the cooling fins 2c are formed are located in the reduced diameter portion 1a of the casing 1.

A large number of cooling fins 2d are formed in the cylinder 2a. The outer diameter of these fins 2d is set approximately equal to the inner diameter of the reduced diameter portion 1a, so that almost no gap is formed between the outer peripheral surface of the fins 2d and the casing inner wall 1c. However, since the outer diameter of the base 2e that contacts the cylinder 2b of the cylinder head 2a is set smaller than the outer diameter of the fins 2d, there is a gap between the fins 2d and between the outer peripheral surface of the base 2e and the inner wall 1c of the casing. A large number of gaps a are formed therebetween. Therefore, both the front and rear sides of the cylinder head 2a communicate through the gap a.

Further, the outer diameter of the cooling fin 2c of the cylinder 2b is also set smaller than the inner diameter of the reduced diameter portion 1a,
A gap is formed between the outer peripheral surface of the cooling fin 2c and the inner peripheral surface of the reduced diameter portion 1a.

A clutch shaft 2g projects downward from a crankcase 2f of the engine 2, and furthermore, this shaft 2g passes through an opening formed in the lower part of the casing 1 and projects to the outside. The tip of the shaft 2g is connected to the drive side of the clutch 3. Further, a drive pinion gear 4 is attached to the driven side of the clutch 3.
The clutch 3 is a centrifugal clutch, and is connected when the engine 2 rotates at a predetermined speed or higher.

A mast 5, to which a main rotor (not shown) is attached at its upper end, is provided so as to pass approximately along the central axis of the casing 1 and to penetrate the casing 1 in the vertical direction. This mast 5 is rotatably supported by a bearing in the casing 1 and parallel to the crankshaft 2g. A rotor drive gear 6 having internal teeth 6a meshing with the pinion gear 4 is attached to the lower end of the mast 5 via an autorotation clutch 7 formed as a one-way clutch. Therefore, the rotation of gear 6 is transmitted to mast 5, but the rotation of mast 5 is not transmitted to gear 6, so that if the engine stops during flight, the main rotor can rotate freely. ing. Further, the pinion gear 4 and the rotor drive gear 6 constitute a deceleration mechanism that decelerates the rotation of the engine 2 and transmits it to the mast 5.

Furthermore, a mast 5 is attached to the inner wall 1c of the casing 1.
A mounting bracket 8 is fixed at a rear position. The width of the mounting bracket 8 in the left-right direction is set to be considerably smaller than the inner diameter of the casing 1, as shown in FIG. Therefore, there is a relatively large space b between the left and right side surfaces 8a and 8b of the bracket 8 and the inner wall 1c of the casing 1.
are formed so that both the front and rear sides of the bracket 8 are in communication with each other.

In this way, even if the engine 2, the mounting bracket 8, etc. are provided in the internal space of the casing 1, the opening 1b on the front end side of the casing 1 and the opening 1 on the rear end side
d and is in communication with it, allowing air to flow therethrough.

A tail rotor drive shaft 9 is rotatably supported by the mounting bracket 8 at the center of the casing 1 in the longitudinal direction. The rear end of the shaft 9 is connected to a tail rotor (not shown) via a joint 10. In addition, at the front end of the shaft 9,
A cooling fan 11 consisting of an axial flow fan equipped with a large number of impellers 11a is fixed. That is,
The central axis of the cooling fan 11 and the central axis of the cylinder 2b are arranged on the same straight line. Furthermore, a bevel gear 12 is integrally formed approximately at the center of the shaft 9 in the longitudinal direction.

Further, a power transmission shaft 13 is rotatably provided on the mounting bracket 8 and protrudes from the casing 1 in a direction perpendicular to the shaft 9 and downward. Therefore, the shaft 13 is also parallel to the crankshaft 2g. A bevel gear 14 that meshes with the bevel gear 12 is provided at the upper end of the shaft 13. On the other hand, a pinion gear 15 that meshes with the internal teeth 6a of the rotor drive gear 6 is provided at the lower end of the shaft 13. The diameter of this pinion gear 15 is set to be slightly larger than the diameter of the drive pinion gear 4. Therefore, the rotation of the engine 2 is transmitted to the tail rotor (not shown) and the cooling fan 11 at a slightly reduced speed.

In this way, the casing 1 includes the engine 2, the mast 5, the tail rotor drive shaft 9
It also functions as a frame to support etc.

Next, the operation of the engine cooling system configured as described above will be explained.

Engine 2 is driven, crankshaft 2g
When the rotational speed reaches a predetermined rotational speed, the clutch 3 is connected and the drive pinion gear 4 rotates.
The rotation of the gear 4 causes the rotor drive gear 6 to rotate at a predetermined reduction ratio. When the gear 6 rotates, the mast 5 rotates and the mast 5
The main rotor at the upper end rotates.

Also, due to the rotation of gear 6, pinion gear 15
rotates, and the tail rotor drive shaft 9 further rotates via the shaft 13 and gears 14 and 12. As a result, the tail rotor rotates and the cooling fan 11 also rotates.

In this way, gears 4, 6, 15, shaft 13,
Crankshaft 2g by gears 14 and 12
A power transmission mechanism is configured to change the direction of the rotation at right angles and transmit it to the shaft 9.

When the cooling fan 11 rotates, the air in the internal space of the casing 1 flows backward, and the opening 1 on the rear end side flows.
It begins to flow out from d. Therefore, since the inside of the casing 1 becomes negative pressure, the opening 1b on the front end side
Air from outside flows into the casing 1. In this way, outside air flows in through the opening 1b, and the space between the gap a of the cooling fin 2d of the cylinder head 2a, the outer periphery of the engine 2, both left and right side surfaces 8a and 8b of the mounting bracket 8, and the inner wall 1c of the casing 1. A flow of air is created which exits from the opening 1d through b.

In that case, since the cylindrical casing 1 guides the air flow, the air will flow approximately linearly. That is, the casing 1 serves as a duct for flowing air. Moreover, since the vicinity of the front end side opening 1b of the casing 1 is widened toward the end, a large amount of air can smoothly flow in.

In this way, all of the outside air flowing in through the opening 1b comes into direct contact with the cylinder head 2a. In that case, the air hits almost the entire surface of the cylinder head 2a uniformly. Therefore, the cylinder head 2a is evenly and efficiently cooled.

Next, the air that has passed through the gap a of the cylinder head 2a comes into contact with the outer circumferential wall of the engine 2, including the cooling fins 2c of the cylinder 2b. In this case, most of the air passing through is brought into contact with the cooling fins 2c by the reduced diameter portion 1a, so that the amount of air that is not used for cooling is extremely small.
Therefore, the engine 2 will be cooled more effectively.

Furthermore, since all of the air flowing in through the opening 1b is used extremely effectively as engine cooling air, there is no need to increase the rotational speed of the cooling fan 11. Furthermore, since there is almost no power loss in the engine 2 that rotates the cooling fan 11, fuel consumption is also extremely low.

The air that cooled the engine 2 is released through the opening 1d on the rear end side.
flows out from the

In addition, in the above-mentioned embodiment, the cooling fan 1
Although the cooling fan 11 is installed at the rear of the engine 2, the present invention is not limited to this, and depending on the relative positions of the engine 2, the mast 5, the speed reduction mechanism, etc., the cooling fan 11 may be installed at the rear of the engine 2. It can also be provided in front of the.

Further, a portion of the casing 1 that is less affected by heat from the engine 2, such as a support portion of the cooling fan 11, is formed of transparent resin, so that the cooling fan 11
By making it visible from the outside, the fashionability of the model helicopter can be improved.

(Effects of the invention) As is clear from the above explanation, according to the invention, the central axis of the engine cylinder and the axis of the rotating shaft of the axial flow fan are made to approximately coincide within the cylindrical casing. Therefore, the cylinder and the axial fan are arranged in series on the same straight line. Moreover, the power of the engine is transmitted to the rotating shaft of the axial flow fan using a power transmission mechanism that transmits the rotation of the crankshaft by changing the direction almost at right angles. It will be rotated.

Therefore, the cooling air generated by the rotation of the axial fan directly contacts the cylinder head without being deflected. Since the cooling air uniformly hits almost the entire surface of the cylinder head, the engine can be cooled extremely effectively.

Moreover, since there is almost no wasted air that is not used for engine cooling, a large amount of air can be sent to the cylinder head without significantly increasing the rotational speed of the cooling fan. Therefore, the cooling fan can be rotated efficiently and power loss of the engine can be reduced. Fuel consumption is thereby significantly reduced.

Furthermore, since the casing that supports the engine and cooling fan guides the flow of cooling air, special parts such as a cooling cover are not required, and the number of parts can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of an engine cooling system for a model helicopter according to the present invention, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. 3 is a line - in FIG. FIG. 1...Casing, 2...Engine, 2b...
Cylinder, 2g... Crankshaft, 4... Drive pinion gear (power transmission mechanism), 6... Rotor drive gear (power transmission mechanism), 9... Tail rotor drive shaft (rotating shaft of cooling fan), 11... Cooling Fan (axial flow fan), 12...
...Bevel pinion gear (power transmission mechanism), 13...
...Power transmission shaft (power transmission mechanism), 14...
Bevel pinion gear (power transmission mechanism), 15...
Pinion gear (power transmission mechanism).

Claims (1)

[Claims for Utility Model Registration] The central axis is defined as the longitudinal direction of the fuselage, and the engine is supported so that the central axis of the cylinder almost coincides with the central axis, and cooling air is allowed to flow through the internal space. a cylindrical casing, which is rotatably supported in a position different from the supporting position of the engine in the casing, with the axis of a rotating shaft substantially coinciding with the central axis of the casing; An engine cooling device for a model helicopter, comprising: an axial flow fan that generates a flow rate; and a power transmission mechanism that transmits the rotation of a crankshaft of the engine to a rotating shaft of the axial flow fan by changing the direction at a substantially right angle.