JPS6140864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device for an internal combustion engine, particularly suitable for use in an internal combustion engine mounted on a motorcycle.

In internal combustion engines for motorcycles, etc., a transmission case with a crank case and a transmission case is installed below the cylinder block, and the engine crankshaft and output shaft are installed side by side within this transmission case.
It is known that these are connected via a V-belt type automatic continuously variable transmission so that the gear ratio can be automatically changed depending on the throttle operation of the engine and the driving conditions of the vehicle. However, the continuously variable transmission is generally housed in a sealed transmission case, and has heat-generating parts such as the drive and the contact area between the driven pulley and the V-belt, and also houses other equipment such as the clutch and reducer. As a result, the temperature inside the transmission case tends to rise, and this tendency is particularly strong when the transmission case is made more compact.

The present invention has been made in view of the above-mentioned circumstances, and is capable of effectively forced cooling of the inside of the transmission case of an engine. An air exhaust port is opened on the side of the case facing away from the continuously variable transmission, and a cooling air passage is formed in the axial direction between the crankshaft and the output shaft in the transmission case. It communicates with the air guide and exhaust ports.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the device of the present invention is implemented in a two-stroke internal combustion engine for a motorcycle will be described below with reference to the drawings. In the following explanation, "front, rear" and "left, right" refer to the body frame F of the motorcycle.
I say to.

In Figure 1, the motorcycle body frame F
is equipped with a two-stroke internal combustion engine. The engine body E of this engine includes a cylinder block 1 tilted forward with respect to the vehicle body frame F, and a transmission case 2 integrally connected to the lower part of this block 1.
This transmission case 2 has a crank chamber 3 in its front part.
However, a mission chamber 4 is also formed at the rear thereof. The transmission case 2 has left and right cover cases 2 2 , 2 on the left and right sides of a case main body _{2 1} divided into left and right halves.
₃ are combined into one body. A crankshaft 5 is rotatably supported in the crank chamber 3 of the transmission case 2, and a crank pin ₅₁ of the crankshaft 5
A piston 8 which is slidably fitted into a cylinder 7 via a connecting rod 6 is connected to the piston 8 . In the transmission chamber 4 of the transmission case 2, an output shaft 9 is rotatably supported parallel to the crankshaft 5.

A V-belt type automatic continuously variable transmission T, which is suspended between the crankshaft 5 and the output shaft 9, is disposed inside one side of the transmission case 2. This transmission T is conventionally known, so to briefly explain its structure, a drive pulley 10 is provided at the right end of the crankshaft 5, and a drive pulley 10 is provided at the right end of the output shaft 9. Large diameter driven pulley 1
1 is provided, and an endless V-belt 12 is suspended between these pulleys 10 and 11. The drive pulley 10 includes a fixed drive pulley half ₁₀₁ fixed to the crankshaft 5 and a movable drive pulley half 1 supported slidably in the axial direction by the crankshaft 5.
The movable drive pulley half ₁₀₂ is equipped with a speed change weight roller 13 that receives centrifugal force and moves it closer to the fixed _drive pulley half ₁₀₁ . The pulley 11 includes a fixed driven pulley half 111 fixed to a hollow pulley shaft 14 rotatably supported on the output shaft 9, and a fixed driven pulley half ₁₁₁ fixed to the pulley shaft 14, which is rotatably supported on the output shaft 9.
It consists of a movable driven pulley half 11 ₂ which can be slid axially on the movable driven pulley half 11 ₂ , which is biased by a pulley spring 15 towards the fixed driven pulley half 11 ₁ .

A centrifugal clutch C for automatic starting is provided on the output shaft 9 and inside the driven pulley 11. Since this centrifugal clutch C is also conventionally known, its structure will be briefly described. A drive plate 17 supporting a clutch weight 16 is fixed to the end of the pulley shaft 14, and is splined to the output shaft 9. A clutch outer 19 is fixed to the clutch shaft 18, and when the rotational speed of the pulley shaft 14 exceeds a set value, the clutch weight 1
6 engages with the clutch outer 19 and the pulley shaft 14
is connected to the output shaft 9.

The output shaft 9 is located at the rear center of the transmission case 2.
The reduction gear case 20 surrounds the left half of the
is formed, and a reduction gear mechanism G is assembled within this reduction gear case 20. A reduction shaft 21 is rotatably supported in the reduction gear case 20 in parallel with the output shaft 9, and this reduction shaft 21 is integrally provided with a large diameter first reduction gear 22 and a small diameter second reduction gear 23. . The first reduction gear 22 is meshed with a drive gear 24 that is integral with the output shaft 9, and the second reduction gear 23 is a large diameter gear that is integral with a final shaft 26 that is rotatably fitted into the left end of the output shaft 9. It meshes with the third reduction gear 25. The final shaft 26 is connected to the reduction gear case 20
It is rotatably supported by the gear case 20, and its left half protrudes outside the reduction gear case 20. A drive sprocket 28 of a chain reduction mechanism 27 is fixed thereto, and this sprocket 28 is connected to a rear wheel (not shown) via an endless chain 29. Linked. Therefore, when the crankshaft 5 is rotated by engine operation, this rotation is transmitted to the output shaft 9 via the V-belt type automatic continuously variable transmission T, the centrifugal clutch C, and the reduction gear mechanism G; It is then transmitted to the rear wheels via the final shaft 26 and the chain reduction mechanism 27.

To the left of the final shaft 26 is a pedal drive shaft 3 rotatably supported by the left cover case ₂₂ .
0 is arranged in tandem on the same axis as the final shaft 26, and this pedal drive shaft 30 is interlocked with a pedal crank (not shown) via a chain drive mechanism 31. Final shaft 26 and pedal drive shaft 3
A clutch ring 32 is slidably fitted on the outer periphery of the clutch ring 32 to connect them together or disconnect them, and an operating handle 33 is connected to the clutch ring 32. When the clutch ring 32 is in the engaged position as shown in FIG. 1, the pedal drive shaft 30 and the final shaft 26 are connected, and the final shaft 26 can be driven by the driver's pedal depression. It becomes possible to run. Further, when the operating handle 33 is shifted to the left as shown by the chain line in FIG. 1, the clutch ring 32 is also shifted to the left and the connection between the final shaft 26 and the pedal drive shaft 30 is severed.

An alternator A is connected to the left end of the crankshaft 5. Further, a pinion shaft 34 is provided between the crankshaft 5 and the output shaft 9, and an internal gear 36 connected to the starting kick shaft is meshed with a pinion 35 at the left end of the pinion shaft 34, and an internal gear 36 is engaged with the right end of the pinion 35. The starting gear 37 can be engaged with and disengaged from a driven gear 38 on the crankshaft 5.

Note that Ac and Ca in FIG. 1 are the air cleaner and carburetor of the intake system of the engine body E.

Incidentally, a new cooling device is provided in the transmission case 2 to effectively cool the continuously variable transmission T, centrifugal clutch C, reduction gear mechanism G, and generator A incorporated therein. Next, the specific configuration of this cooling device will be explained.

As shown in FIGS. 1, 2 and 7, an inner case 4, which is a part of the transmission case 2, is attached to the inner wall of the right cover case _{2 to 3} .
The inner case 40 and the right cover case ₂₃ form an air guide passage 41. An inlet 42 of this air guide passage 41 is opened in the rear wall of the transmission case 2 and connected to an air cleaner 43, and the inlet of this air cleaner 43 is opened to the atmosphere.
Further, the outlet 44 of the air guide passage 41 is communicated with an air guide port 45 opened in the inner case 40 on the side of the driven pulley 11. Note that the air guide passage 41 may be formed only by the right cover case ₂₃ .

A bowl-shaped drain plate 46 is fixed to the right end of the output shaft 9, and the outer peripheral edge of the drain plate 46 faces the air guide port 45. Further, as clearly shown in FIG. 7, a drain passage 47 communicating with the outlet 44 is formed by the right cover case ₂₃ and the inner case 40, and an outlet 48 of the drain passage 47 is opened at the lower part of the transmission case 2. , a porous material 49 is provided there. A suction fan 50 is provided on the back side of the fixed driven pulley half 111 of the driven pulley ₁₁ , and this suction fan 50 is connected to the driven pulley 1.
1, clean cooling air from an air cleaner 43 can be introduced into the transmission case 2 through the air guide passage 41. Also drive pulley 1
A stirring blade 51 is integrally provided on the back side of the fixed drive pulley half 10 ₁ of 0, and this stirring blade 51
acts to stir the cooling air introduced into the transmission case 2 and cause the cooling air to flow in its radial direction.

As shown in FIGS. 3, 4, and 5, inside the transmission case 2, cooling air passages 52, 53, and 54 are located on the outer periphery of the automatic continuously variable transmission T, between the crankshaft 5 and the output shaft 9, and below them. are formed, and the cooling air passages 52, 53 and 54 have a third
Cooling air flows sequentially as shown by solid line arrows in Figures 4 and 5. As clearly shown in FIG. 5, a part of the bottom wall of the transmission case 2 bulges downward, and the bulge 5
An air exhaust port 56 is opened in the side wall of 5, and a louver 57 is formed in the air exhaust port 56.

Next, the operation of the embodiment of the present invention will be explained.

When the automatic continuously variable transmission T is now driven by the operation of the engine, the fixed driven pulley half _{11 1} of the driven pulley 11 is moved as shown by the solid line in FIGS. 2 and 7.
The suction fan 50 fixedly sucks clean cooling air from the air cleaner 43 into the transmission case 2 through the air guide passage 41. In this case, the moisture mixed in the cooling air is blown away in the radial direction by the draining plate 46, hits the inner wall surface of the right cover case ₂₃ , and is drained through the drain passage 47 as shown by the dotted line in FIG. Water is drained to the outside from the port 48.

The cooling air from which moisture has been removed is forced to be sent in the radial direction of the driven pulley 11 by the suction fan 50. The pressurized cooling air around the outer circumference of the driven pulley 11 is
The cooling air flows through the cooling air passage 52 between the automatic continuously variable transmission T and the transmission case 2 toward the drive pulley 10, and is stirred by the stirring blade 51 provided on the fixed drive pulley half ₁₀₁ of the pulley 10. To effectively cool heat generating parts of a transmission T, such as friction contact parts of a V-belt 12, a driven pulley 11, and a drive pulley 10. The cooling air that has cooled the automatic continuously variable transmission T passes between the drive pulley 10 and the driven pulley 11 as shown in FIGS.
flows along the axial direction of the shafts 5 and 9 and cools the centrifugal clutch C and the reduction gear case 20 from the clutch outer 19 through the outer periphery of the reduction gear case 20. It reaches the opposite side of T, where some of the cooling air passes around the outer circumference of the generator A and cools the generator A.
As described above, the cooling air that has sequentially forcedly cooled the automatic continuously variable transmission T, centrifugal clutch C, reduction gear mechanism G, and generator A in the transmission case 2 is directed toward the crankshaft as shown in FIGS. 5 and is discharged to the outside from the exhaust port 56 through the cooling air passage 54 under the output shaft 9.

By the way, the V-belt 12 of the automatic continuously variable transmission T
, drive pulley 10 and driven pulley 1
The heat generating part such as the contact part with the suction fan 50
The cooling air that is forcibly drawn into the transmission case 2 can be effectively cooled, and the distance between the crankshaft 5 and the output shaft 9 can be shortened to make the transmission case 2 more compact. Also, it becomes possible to prevent an excessive temperature rise inside the case 2, and it is possible to prevent the V-belt 12 from deteriorating due to heat generation.

Further, since the driven pulley 11 is rotated at a higher speed as the vehicle speed increases, the amount of cooling air sucked by the suction fan 50 increases as the rotational speed of the driven pulley 11 increases, that is, as the amount of heat generated by the heat generating section increases. , good cooling efficiency,
No Juan Ross.

As described above, according to the present invention, the transmission case 2
A cooling air guide port 45 is opened on the side of the continuously variable transmission T, and an air exhaust port 56 is opened on the side of the case 2 facing away from the continuously variable transmission T, and the crankshaft 5 and the output shaft 9 Cooling air passages 53 and 54 are formed between them in the axial direction, and these cooling air passages 5
3 and 54 are communicated with the air guide port 45 and the air exhaust port 56, after effectively cooling the heat generating part of the continuously variable transmission T inside the transmission case 2, the cooling air is used to cool the centrifugal clutch inside the transmission case 2. C, reduction gear mechanism G, generator A, and other devices can also be cooled, and the service life of the continuously variable transmission T and other devices can be increased. Furthermore, even if the effective area of the transmission case 2 is reduced, an excessive temperature rise inside the case 2 can be suppressed, and when the transmission case 2 is made more compact, there is no restriction due to the temperature rise inside the case 2. It disappears.

[Brief explanation of the drawing]

Fig. 1 is a side view of an internal combustion engine equipped with the device of the present invention mounted on the body frame of a motorcycle, Fig. 2 is a developed cross-sectional view taken along the line of Fig. 1, and Fig. 3 is a
Figure 2 - Side view of the transmission case along line, No. 4
The figures are a side view of the transmission case along the line in Figure 2, Figure 5 is a sectional view along the line in Figure 2, Figure 6 is a side view along the line in Figure 2, and Figure 7 is a side view along the line in Figure 1. FIG. 1...Cylinder block, 2...Transmission case,
3... Crank chamber, 4... Mission room, 5...
Crankshaft, 9... Output shaft, 45... Air guide port, 5
6...Exhaust port, T...Automatic continuously variable transmission.

Claims (1)

[Claims] 1 A transmission case 2 having a crank chamber 3 and a transmission chamber 4 therein is installed below the cylinder block 1, and a crankshaft 5 and an output shaft 9 are installed side by side in the transmission case 2. A continuously variable transmission T connecting the crankshaft 5 and the output shaft 9 is provided on one side of the case 2, and the rotation of the crankshaft 5 is transmitted to the output shaft 9 via the continuously variable transmission T. In the internal combustion engine configured as above, a cooling air guide port 45 is opened on the side of the continuously variable transmission T of the transmission case 2, and an air exhaust port 56 is opened on the side of the case 2 facing away from the continuously variable transmission T. cooling air passages 53, 54 are formed between the crankshaft 5 and the output shaft 9 in the axial direction thereof;
54 communicates with the air guide port 45 and the air exhaust port 56.