JP2577022B2 - Engine timing belt mechanism cooling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a timing belt mechanism of a motorcycle engine, for example, in which a cam shaft is driven by a timing belt, and mainly cools the timing belt of the mechanism with outside air. In particular, the arrangement of the intake port and exhaust port so that noise (hereinafter referred to as belt noise) such as the noise of engagement between the belt and the pulley, the rattling noise of the belt and the operation noise of the cooling fan is not directly emitted to the outside. Regarding the structure.

(Prior Art) In a camshaft driving device for an engine, a timing belt mechanism using a timing belt instead of a timing chain has been adopted from the viewpoint of noise reduction and the like. In such a camshaft driving device, the timing belt mechanism is housed in the belt chamber to prevent the timing belt mechanism from being exposed to the outside. There is a need to. Therefore, a timing belt mechanism cooling device that can ventilate the air in the belt chamber has been conventionally used. Conventionally, as this cooling device, for example,
As proposed in Japanese Patent Publication No. 180018, there is a belt pulley having a fan function for blowing air, and a cover constituting a belt chamber having an intake port and an exhaust port.

(Problems to be Solved by the Invention) However, in the conventional cooling device of the timing belt mechanism, since the intake port and the exhaust port are opened outward, the belt noise is directly emitted to the outside. Engine noise tends to increase. In addition, since it is similarly open outward, earth and sand, rainwater, and the like due to so-called chipping from the road surface easily enter the belt chamber from the intake port or the like. Such a problem is particularly remarkable in a motorcycle engine mounted to be exposed to the outside.

In view of the above problems, an object of the present invention is to provide a timing belt for an engine capable of reducing the noise of the entire engine by suppressing the outward emission of belt noise and suppressing the intrusion of earth and sand into the belt chamber. It is in providing a mechanism cooling device.

(Means for Solving the Problems) The present invention provides an engine timing belt mechanism cooling device for cooling a camshaft driving timing belt wound between a crankshaft and a camshaft with outside air. A belt chamber for accommodating the timing belt mechanism is formed on the side with a gap between the belt chamber and the engine body, and an intake port and an exhaust port are formed on an inner wall of the belt chamber located on the engine body side. It is characterized by.

(Operation) According to the timing belt mechanism cooling device of the present invention, the intake and exhaust ports are formed on the inner wall of the belt chamber located on the engine body side, so that the intake and exhaust ports face the engine body side. As a result, the belt noise from the belt chamber is emitted to the engine main body side, and is not emitted directly to the outside, but the noise of the entire engine can be reduced accordingly. Further, since the intake port and the like face the engine body side, intrusion of earth and sand can be suppressed.

Here, when the belt chamber is constituted by the side wall of the engine body and the cover attached thereto, the intake port and the exhaust port must be opened outward as in the device described in the above-mentioned publication. In the above, the belt chamber was formed with a gap between the engine body and the belt chamber formed independently of the engine body by an inner wall covering the engine body side of the belt and an outer wall covering the outer side of the belt. As described above, the intake port and the exhaust port can be opened toward the engine main body, and as a result, the above-described operation can be obtained.

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

In FIG. 6, reference numeral 1 denotes a motorcycle employing the apparatus of this embodiment, and a front fork 4 for rotatably supporting a front wheel 3 at a lower end at a front end of a body frame 2 of the motorcycle has a shaft rotatable left and right. A fuel tank 5 and a seat 6 are mounted on the upper part, and a rear arm 8 rotatably supporting the rear wheel 7 at the rear end is pivotally supported on the lower rear end.

An engine unit 9 is mounted substantially at the center of the body frame 2. This engine unit 9
Is an L-type four-stroke air-cooled engine viewed from the side, which is connected to a crankcase 10 such that a substantially horizontal front cylinder unit 11 and a substantially vertical rear cylinder unit 12 are opened 90 degrees back and forth. . And each of the above cylinder units
As shown in FIG. 4, the cylinders 11 and 12 are formed by laminating cylinder heads 11b and 12b and head covers 11c and 12c on cylinder bodies 11a and 12a and fixing them with stud bolts (not shown). The cylinder body 12a is offset in the axial direction of the crankshaft 13 by a width of the connecting rods 14a and 14b in a direction opposite to a belt chamber 16 described later.
A cam shaft is provided at the boundary between b and 12b and the head covers 11c and 12c.
15a and 15b are arranged in parallel with the crankshaft 13.

The front and rear cylinder units 11, 12 and the side surfaces of the crankcase 10 are provided with belt chambers so as to cover them.
16 is formed with a gap between the side walls of the cylinder units 11 and 12. The belt chamber 16 has an L-shape in a side view in accordance with the shape of the engine. The belt chamber 16 is a left-right split type including an L-shaped inner cover 17, front and rear outer covers 18a and 18b, and an ACG cover 21. ing. The inner cover 17 is a rubber bush 19a-1
The bolt is fixed to the head cover 12c, the bearing wall 10a of the crankcase 10, and the head cover 11c via 9d.

An intake port 17a is formed substantially in the center of the inner cover 17 on the side of the front cylinder unit 11, and is formed in a triangular shape as shown in FIG. Is filled with an air filter 33. An exhaust fan 34 is formed at the upper end of the rear side of the inner cover 17 on the cylinder unit 12 side.
The casing 34a is integrally formed with a casing 34a having a cochlear shape and having an exhaust port 34b at the distal end of the inner cover 17, and a blower blade 34c is rotatably arranged at the center of the casing 34a. The blade 34c is mounted and fixed on the cam shaft 15b. The outer covers 18a and 18b are fixed to the inner cover 17 with bolts via seal packings 19e.

A rotating member 20a of a generator (ACG) 20 is bolted and fixed to an outer end of the crankshaft 13 protruding from a bearing wall 10a, and an ACG cover 21 is disposed outside the rotating member 20a. I have. The ACG cover 21 has a cap shape surrounding the rotating member 20a, is fixed to a peripheral wall 10b erected around a bearing wall 10a of the crankcase 10 by bolts, and a bottom wall portion of the cover 21 is provided. The coil 20b is fixed.

A drive pulley 22 having engagement teeth formed on the outer peripheral surface is attached to the inside of the rotating member 20a of the crankshaft 13, and is fixed by a key 23a and a lock nut 23b. In addition, driven pulleys 24 and 25 each having an engaging tooth are attached to the protruding ends of the cam shafts 15a and 15b in the belt chamber 16 and are fixed by bolts, and the driven pulley 25 is provided outside the blowing blade 34c. It is located in. And the driving pulley 2
Between the driven pulleys 24 and 25, one timing belt 25a meshing with the engagement teeth is wound.

A first idler pulley is provided on the bearing wall 10a of the crankcase 10 so as to face the crankshaft 13.
26, a second idler pulley 27 and a tensioner pulley 28 are respectively disposed before and after a line connecting the idler pulley 26 and the crankshaft 13 as shown in FIG. The three pulleys 26-28 are crankcase
The second idler pulley 27 and the tensioner pulley 28 are
And the driven pulley 24 or 25 is located substantially inside the tangent line.

The first and second idler pulleys 26 and 27 are of a fixed type and have smooth outer peripheries on support pins 26a and 27a implanted in the bearing wall 10a of the crankcase 10 as shown in FIGS. It is constructed by mounting cylindrical pulley bodies 26b and 27b via bearings. 26c is an engine suspension bolt for connecting the left and right crankcases.

The above-mentioned tensioner pulley 28 is of a movable type, and is configured such that a cylindrical pulley main body 28b is rotatably mounted on the tip end of a swing arm 29 via a bearing 28a. A fulcrum 29a of the swing arm 29 is rotatably mounted on a support pin 30 provided between the first idler pulley 26 and the crankshaft 13 of the bearing wall 10a. Also, this fulcrum
A biasing spring 31 is mounted on 29a, and one end of the biasing spring 31 is locked by a locking pin 29b implanted on the side of the pulley body 28b of the swing arm 29, and the other end is the same as the above-described one. The idler pulley 27 is engaged with a support pin 27a, whereby the tensioner pulley 28 is urged to rotate in a direction for applying a tension to the timing belt 25a, that is, counterclockwise in FIG.

Further, a drive shaft 41a is connected to a connection piece 29c protruding from the tip of the swing arm 29, and this is in contact with a cylindrical body 41 of the auto tensioner 32 as described later. The casing 40 of the auto-tensioner 32 is bolted and fixed on the bearing wall 10a of the crankcase 10. In this manner, the auto-tensioner 32 and the swing arm 29 of the tensioner pulley 28 Is disposed so as to sandwich the crankshaft 13.

The above-mentioned auto tensioner 32 is of a screw type. As schematically shown in FIG. 5, a cylindrical body 41 having a female thread is screwed onto a shaft 42 having a thread at the tip. Is disposed in a casing 40, a helical spring 43 is mounted on the shaft 42, and one end of the spring 43 is engaged with the cutout 42a of the shaft 42, and the other end is connected to the casing 40.
The upper end of the cylindrical body 41 is in contact with a drive shaft 41a coupled to a connecting piece 29c of the swing arm 29.

 Next, the operation and effect of this embodiment will be described.

In the engine of this embodiment, when the crankshaft 13 rotates,
The camshafts 15a and 15b are rotationally driven by the timing bell 25a, whereby the blower blades 34c of the exhaust fan 34 are rotated by the camshaft 15b. Then, the inside of the belt chamber 16 becomes a negative pressure, and the outside air is sucked into the belt chamber 16 from the intake port 17a of the front cylinder unit 11 through the gap. The suction air passes through the rear cylinder unit 12 while cooling the timing belt 25a from the front cylinder unit 11 side, is introduced into the casing 34a of the exhaust fan 34, and is discharged from the exhaust port 34b into the gap. .

Note that the cam shafts 15a, 15
In driving b, the urging spring 31 of the tensioner pulley 28
And the timing belt 25a by the auto tensioner 32
Is adjusted to a predetermined value.

As described above, in this embodiment, the timing belt cooling air intake port 17a and the exhaust port 34b are opened on the gap side between the belt chamber 16 and the cylinder units 11 and 12, that is, on the back side of the belt chamber 16, so that the timing Belt 25a and each pulley 24
Belt noises such as meshing noises with -28 are not emitted directly to the outside, and the noise of the entire engine can be reduced accordingly. Further, since the cooling air is sucked from the back side of the belt chamber 16 and is discharged to the back side, the discharge of the intake sound and the exhaust sound to the outside is also suppressed, and the engine noise can be reduced from this point as well. .

Further, the intake port 17a and the exhaust port 34b are formed toward the back side of the belt chamber 16, that is, without being exposed to the outside of the engine. It is possible to prevent the raised earth and sand, rainwater, and the like from entering the belt chamber 16 from this opening, and the belt life can be extended accordingly.

In this embodiment, the intake port 17a and the like are connected to the cylinder unit 1.
The reason why the belt chamber 16 was able to be opened to the side 1 and 12 is that the belt chamber 16 was formed separately from the engine body by the inner cover 17 and the outer cover 18 and a gap was opened. The open structure prevents heat from the engine body, especially the cylinder bodies 11a and 12a, from being transmitted to the belt chamber 16, and improves the cooling efficiency of the timing belt because running air passes through this gap. As a result, the belt life can be extended. In addition, since the blades 34c dedicated to air blowing are mounted on the cam shaft 15b, a sufficient air blowing amount can be secured. On the other hand, when such a dedicated blade is mounted, there is a concern that the engine width may be increased by the axial length of the blade. On the other hand, in this embodiment, since the blower blades 34c are mounted on the cam shaft 15b on the cylinder unit 12 side after being offset to the opposite side of the belt chamber 16, the increase in the engine width can be prevented. That is, the axis of the cam shaft 15b on the rear cylinder unit 12 side is
The offset amount (the connecting rod 14
a or 14b), and
Therefore, a space is formed between the driven pulley 25 and the inner deviating amount, and the blower blades 34c are disposed by using the empty space. Therefore, there is no problem that the blower blades increase the engine width.

In general, hot air has a low specific gravity and easily rises, but in this embodiment, the front and rear cylinder units are arranged in an L shape, and the blowing blade 34c is mounted on the cam shaft 15B located at the highest position, Since the exhaust port 34b is arranged in this portion, and the intake port 17a is arranged in the lowest position of the front cylinder unit 11, cooling air can be reliably blown with one blower blade 34c,
It can be cooled efficiently.

Also, when the cylinder unit is placed before and after,
Although the rear cylinder unit is obstructed by the front cylinder unit and the traveling wind is difficult to hit, the temperature of the rear belt chamber is likely to rise.However, in this embodiment, the exhaust fan is disposed on the rear cylinder unit 12 side. With the provision of 34, the ventilation of the rear belt room is ensured and the temperature rise can be suppressed.
Further, in the present embodiment, the front cylinder unit 11 is substantially horizontal and the rear cylinder unit 12 is substantially vertical, so that the front cylinder unit does not interfere.
The traveling wind easily hits the rear cylinder unit 12, and the cooling efficiency can be improved from this point as well. From the viewpoint of heat conduction to the belt chamber 16, the camshaft conducts heat, but in the present embodiment, since the blowing blade is attached to this camshaft, the above-mentioned conducted heat is effectively reduced. And the temperature rise of the belt chamber can be suppressed.

In the above-described embodiment, the engine in which the cylinder units are arranged in an L-shape before and after is described. However, the scope of the present invention is not limited to such an engine. The present invention can be applied if it is formed with a gap from the main body.

FIGS. 7 and 8 show another embodiment adopted in a parallel two-cylinder four-stroke air-cooled engine.
4 and FIG. 4 indicate the same or corresponding parts. Also in the present embodiment, the belt chamber is formed with a gap from the cylinder unit, but in the present embodiment, the intake port 17a is formed on the peripheral wall 10 of the crankcase 10 that forms a part of the inner cover 17.
It is formed to open at the lower end of b and toward the crankcase 10 as the engine body.

In this embodiment, similarly to the first embodiment, the belt noise can be prevented from being directly emitted to the outside to reduce the noise of the entire engine, and the intrusion of earth and sand can be prevented to extend the life of the belt. it can.

In the above embodiment, the air-cooled engine has been described. However, the present invention can be applied to a water-cooled engine.

(Effects of the Invention) As described above, according to the timing belt mechanism cooling device of the present invention, the belt chamber is formed with a gap from the engine body, and the intake and exhaust ports for cooling air are provided inside the belt chamber. Since it is formed on the wall, it has the effect of suppressing the outward emission of belt noise and reducing engine noise, and has the effect of suppressing the intrusion of earth and sand into the belt chamber and extending the life of the belt.

[Brief description of the drawings]

1 to 4 are views for explaining a timing belt mechanism cooling device according to an embodiment of the present invention.
FIG. 4 is a side view showing a state in which an outer cover and a generator are removed, FIG. 4 is a cross-sectional development view taken along line IV-IV of FIG. 1, FIG. 6 is a side view of a motorcycle using the apparatus of the embodiment, FIG. FIG. 7 is a side view of a timing belt mechanism cooling device according to another embodiment of the present invention. FIG. 2 is a diagram for explaining a cam shaft driving device, and is a sectional view taken along line II-II of FIG. FIG. 3 is also the same as FIG.
FIG. 5 is a cross-sectional view taken along the line III-III, FIG. 5 is a schematic view showing the auto tensioner, and FIG. 8 is a cross-sectional view taken along the line VII-VII in FIG. In the figure, 9 is an engine unit, 11 and 12 are front and rear cylinder units (engine body), 13 is a crankshaft, 15
a and 15b are cam shafts, 16 is a belt chamber, 17 is an inner cover (inner side wall), 17a is an intake port, 22 is a drive pulley, 24 and 25 are driven pulleys, 25a is a timing belt, and 34b is an exhaust port.

Claims (2)

(57) [Claims] An engine timing belt mechanism cooling apparatus for cooling a timing belt mechanism formed by winding a timing belt between a driving pulley fixed to a crankshaft and a driven pulley fixed to a camshaft by outside air.
A belt chamber for accommodating the timing belt mechanism is formed on the side of the engine main body with a gap between the belt main body and the engine main body. An engine timing belt mechanism cooling device, wherein an exhaust port is formed. 2. The engine according to claim 1, wherein said engine is a V-type engine having front and rear cylinder units arranged in a V-shape in front and rear of the vehicle, wherein said intake port is located near a crankshaft, and said exhaust port is provided for each cylinder unit. 2. The cooling device according to claim 1, wherein the cooling device is formed near the camshaft.