JP2554178Y2 - Crankcase for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankcase for an internal combustion engine mounted on a motorcycle or the like, and more particularly to a crankcase configured to be divided so as to reduce the case width. It is.

2. Description of the Related Art As shown in FIG. 4, a conventional internal combustion engine mounted on a motorcycle or the like includes a transmission case 04 in which a crank chamber 02 and a transmission chamber 03 are juxtaposed below a cylinder block 01. It is connected. Then, a crankshaft 05 and an output shaft 06 are arranged side by side in a transmission case 04, and a drive free 07 provided on the crankshaft 05 and a driven pulley 08 provided on the output shaft 06 are wound between these pulleys 07, 08. And a continuously variable transmission composed of the V-belt 09 arranged on one side of the transmission case 04. Thereby, the rotation of the crankshaft 05 is automatically changed by the output shaft 06 via the continuously variable transmission while automatically changing the gear ratio according to the throttle operation of the engine and the running conditions of the vehicle.
Is transmitted to

In such an internal combustion engine, for example,
No. 23 discloses a driven pulley 08
A cooling air introduction port 010 is provided to face the rear surface of the driven pulley 08, and a suction fan 011 is provided on the rear surface of the driven pulley 08. The suction fan 011 rotates integrally with the driven pulley 08 and takes in cool air from the inlet 010 to cool the members inside the transmission case 04, particularly the cylinder block 01.

Problems to be Solved by the Invention As this kind of crankcase, one that is divided into two parts, a left part and a right part of the case, is generally used. Each of the divided portions supports a member arranged inside the case.

However, in the conventional split crankcase,
The mating surfaces of the divided members are on the same plane. Therefore, for example, an end portion of one side of the case of the reduction gear mechanism projects toward the one side of the case, and the case cover on the one side of the case protrudes toward the one side, so that the effective width W of the entire internal combustion engine is increased. Has become a bottleneck in downsizing vehicles.

Means for Solving the Problems and Effects of the Invention The present invention relates to an improvement of a crankcase for an internal combustion engine which has solved such a problem, and relates to a crankshaft as an input shaft of a V-belt continuously variable transmission, and a V-belt continuously variable transmission. The driven shaft, which is the output shaft of the transmission, is supported by the crankcase,
In a crankcase for an internal combustion engine in which a gear shaft of a reduction gear mechanism having the driven shaft as an input shaft is supported by the crankcase, the crankshaft is supported by one side of the case and another side of the case, The shaft and the gear shaft of the reduction gear mechanism are supported by a case output part and the case one side located on the same side as the case other side with respect to the case one side, and the case one side and the case The mating surface with the output portion is formed stepwise in the case other side direction than the mating surface of the case one side portion and the case other side portion, and the case other side portion and the case output portion are It is characterized by being arranged in contact with one side of the case.

As described above, the present invention supports the crankshaft at one side of the case and the other side of the case, and the gear shaft of the reduction gear mechanism is on the same side of the one side of the case as the other side of the case. The located case output portion, supported by the case one side, the mating surface of the case one side and the case output portion,
Because the case other side portion and the case output portion were positioned differently to the case other side than the mating surface of the case one side portion and the other side portion, and were arranged in contact with the case one side portion. An end portion of one side of the case of the reduction gear mechanism is prevented from protruding toward one side of the case, and a case cover on one side of the case is prevented from protruding toward the one side. Of the internal combustion engine can be miniaturized.

In addition, in the present invention, the case output portion constituting a part of the wall of the reduction gear mechanism is separate from the other side portion of the case involved in supporting the crankshaft, so that it is not necessary to increase the accuracy of the crankcase shaft. The maintenance and maintenance of the crank chamber and the reduction gear mechanism can be performed separately and independently.

Embodiment Hereinafter, an embodiment in which the present invention is applied to a motorcycle will be described with reference to FIGS. 1 to 3.

The internal combustion engine mounted on the motorcycle A includes a power unit including a cylinder block 1, a crank chamber 2, a clutch chamber 3 and a transmission chamber 4, as shown in FIG. This power unit is entirely housed in the engine shroud 51, suction fan cover 52 and crankcase 6.

The cylinder 11 of the cylinder block 1 has a piston 12
The piston 12 is connected to a crankshaft 21 via a connecting rod 13. On the inner wall side of the cylinder 11, the air-fuel mixture in the crank chamber 2 is supplied to the cylinder 11 in accordance with the reciprocating operation of the piston 12.
A scavenging port 14 to be introduced into the inside is provided.

Further, an intake pipe 18 communicates with the crank chamber 2, and a reed valve 17 is attached to an opening of the crank chamber 2.
11, an exhaust port 19 is provided.

Furthermore, the cylinder on the opposite side of the crankshaft 21
At the end of 11, a spark plug attached to the cylinder head 15
16 is facing.

In addition, the crankshaft 21, which is the input shaft of the V-belt continuously variable transmission, has the connecting rod 13 eccentrically attached thereto in order to change the forward and backward movements of the piston 12 into rotational movement.

Further, on one side of the crankshaft 21, a drive fixed face 22a and a drive movable face 2 constituting the drive pulley 22 are provided.
2b is provided. The drive movable face 22b is
It is fitted to the crankshaft 21 via the sleep 22c.

Further, a cam plate 23 is fixed to an end of the crankshaft 21 further outside the drive movable face 22b.
The peripheral portion of the cam plate 23 is in contact with the driving movable face 22b in a fitted state, and a weight 24 is interposed between the driving movable face 22b and the cam plate 23.

On the other side of the crankshaft 21, a suction fan 25 is fixed so as to rotate integrally with the crankshaft 21. The suction fan 25 is for taking in cool air from a cooling air inlet 53 provided in a suction fan cover 52 near the suction fan 25 and cooling various members disposed therein, particularly the cylinder block 1.

Further, the clutch chamber 3 is provided with a driven shaft 31 serving as an input shaft of a reduction gear mechanism 41 having an axial length extending to the transmission chamber 4.

On one side of the driven shaft 31, a driven fixed face 32a and a driven movable face 32b constituting the driven pulley 32 are bearings.
It is fitted to the driven shaft 31 via 36.

Further, the driven fixed face 32a is fixed to the collar 33. On the other hand, the driven movable face 32b is
While being guided by a guide pin 34 inserted in a key groove 33a formed in the driven shaft 31, the driven shaft 31 is movable in the axial length direction. Reference numeral 35 denotes a spring that constantly biases the driven movable pulley 32b toward the driven fixed pulley 32a.

Moreover, the collar 33 is rotatably provided on the peripheral surface of the driven shaft 31 by the bearing 36.

The left end of the collar 33 is fitted to the driven fixed face 32a of the driven pulley 32, and the inner disk 37a is integrally fitted to the right end of the collar 33. In addition, a weight 37c that is in contact with the inner peripheral surface of the outer disk 37b during high-speed rotation is attached to the inner disk 37a. Further, the outer disk 37b is connected to the driven shaft 3 via the sleeve 38.
Spline-joined to 1. The inner disc 37a, the outer disc 37b, and the weight 37c constitute a centrifugal clutch 37.

The drive pulley 22 of the crank chamber 2 configured as described above
A V-belt 39 is stretched between the driven pulley 32 and the driven pulley 32 in the clutch chamber 3, and the drive pulley 22, the driven pulley 32, and the V-belt 39 constitute a V-belt continuously variable transmission.

The driven shaft 31 extending to the transmission chamber 4 has a reduction gear mechanism.
A final shaft 42 is connected via 41. A chain 44 extending to a drive wheel Wr (see FIG. 1) of the motorcycle is suspended on a chain sprocket 43 provided at an end of the final shaft 42.

Of these mechanisms, the cylinder block 1 is covered with an engine shroud 51 and a suction fan cover 52. As described above, the suction fan cover 52 is provided with the cooling air inlet 53 for taking in the cool air and cooling the cylinder 11 and the like.

On the other hand, each member of the crank chamber 2, the clutch chamber 3 and the transmission chamber 4 is supported by a crank case 6.
This crankcase 6 has a split configuration of a case left portion 61, a case right portion 62, and a case output portion 63. That is, the crankshaft 21 is supported by the case left portion 61 and the case right portion 62, and the driven shaft 31, the reduction gear mechanism 41, the final shaft 42, and the like are supported by the case left portion 61 and the case output portion 63. The crankshaft 21, the driving pulley 22, the driven shaft 31, the driven pulley 32, and the like protruding laterally from the case left portion 61 are covered with a left crankcase cover 64.

Reference numeral 65 denotes a mating surface between the case left side portion 61 and the case right side portion 62. Reference numeral 66 denotes a mating surface between the case left side portion 61 and the case output portion 63. The mating surfaces 65 and 66 are stepped as shown in the drawing, and the mating surface 65 is located closer to the left crankcase cover 64 than the mating surface 66.

Reference numeral 67 denotes an engine hanger boss provided on the rear end side of the crankcase 6.

Next, the operation of the power unit described above will be described.

When the engine is operating, the rotation of the crankshaft 21 is transmitted from the driving pulley 22 to the driven pulley 32 via the V-belt 39.
Is transmitted to When this rotation is low speed, the space between the drive fixed face 22a and the drive movable face 22b is sufficiently open,
The V-belt 39 is located near the crankshaft 21 as shown by a solid line in FIG. On the other hand, on the driven pulley 32 side, the driven movable face 32b is pushed by the spring 35 toward the driven fixed face 32a, and the gap between the driven movable face 32b and the driven fixed face 32a is narrowed.
Is separated from the driven shaft 31.

That is, on the crankshaft 21 side, the V-belt 39 travels along an arc trajectory with a small radius, while the driven shaft
On the 31 side, the V-belt 39 runs along an arc trajectory with a large radius. Therefore, the driven pulley 32 with respect to the drive pulley 22
, The power is not transmitted to the transmission chamber 4 in this state.

As the rotational speed of the crankshaft 21 increases, the weight
Large centrifugal force acts on 24. Therefore, weight 24
Is the crankshaft as shown by the dashed line in FIG.
Move away from 21. By the movement of the weight 24, the drive movable face 22b is moved to the drive fixed face 22a.
The V-belt 39 is lifted in the direction away from the crankshaft 21 by being pushed to the side.

On the other hand, on the driven shaft 31 side, since the V-belt 39 is pulled in the direction of the crankshaft 21, the fixed face 32a and the movable face 3
The space between the V belt 39 and the V-belt 39 is pushed closer to the driven shaft 31.

As a result, the V-belt 39 travels along an arc trajectory having a large radius on the crankshaft 21 side, and travels along an arc trajectory having a small radius on the driven shaft 31 side. Therefore, the rotation ratio of the driven pulley 32 to the driving pulley 22 increases, and the driven pulley 32 rotates at high speed.

When the rotation of the driven pulley 32 increases, a large centrifugal force acts on the weight 37c, and the weight 37c is moved to the outer disk 37.
The inner disk 37a is pressed against the inner peripheral surface of b, and power is transmitted to the outer disk 37b. As a result, the rotation of the driven shaft 31 is started, and this rotation is transmitted to the chain sprocket 43 via the reduction gear mechanism 41 and the final shaft 42, and makes the chain 44 circulate.

Here, the mating surface of the case left portion 61 and the case right portion 62
65 is formed stepwise with respect to the mating surface 66 of the case left side portion 61 and the case output portion 63. That is, both mating surfaces 6
A step D is provided between the driven pulley 32 and the centrifugal clutch 37 so that the mating surface 65 is on the left side (the upper side in FIG. 3) so that a sufficient space can be secured around the cylinder block 1.
On the side of the driven shaft 31 equipped with a, the mating surface 66 is set on the right side so that the clutch chamber 3 is widened.

Since the bearing position can be arbitrarily set according to the step D, the crankshaft 21 and the driven shaft 31 can be reduced to a minimum, and the entire engine can be made compact.

Since the case output portion 63 is attached to the case left side portion 61 from the chain sprocket 43 side, the transmission chamber 4
It is not necessary to remove the case left portion 61, the left crankcase cover 64, and the like when performing the maintenance of.

Furthermore, the engine hanger boss 67 is attached to the wide case left portion 61 without being mounted over the split member of the crankcase as in the prior art, so that it is integrally molded with high rigidity and excellent mounting accuracy. Can be used. Therefore, for example, maintenance of the crank chamber 2, the clutch chamber 3, the transmission chamber 4, and the like can be performed while the engine is mounted.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a motorcycle to which the present invention is applied, FIG. 2 is a side sectional view showing an embodiment of an internal combustion engine having a crankcase of the present invention, and FIG. FIG. 4 is a sectional view of a conventional internal combustion engine. 1 ... cylinder block, 11 ... cylinder, 12 ... piston, 13 ... connecting rod, 14 ... scavenging port, 15 ... cylinder head, 16 ... spark plug, 17 ...
Reed valve, 18 ... intake pipe, 19 ... exhaust port. 2 ... Crank chamber, 21 ... Crank shaft, 22 ... Drive pulley, 22a ... Drive fixed face, 22b ... Drive movable face, 22c ... Sleeve, 23 ... Cam plate, 24
... weight, 25 ... suction fan. 3 ... clutch chamber, 31 ... driven shaft, 32 ... driven pulley,
32a: driven fixed face, 32b: driven movable face,
33c …… Sleeve, 33 …… Color, 33a …… Keyway, 34…
… Guide pin, 35 …… spring, 36 …… bearing,
37 …… Centrifugal clutch, 37a …… Inner disc, 37b…
... outer disc, 37c ... weight, 38 ... sleeve, 39 ... V-belt. 4 Mission room, 41 Reduction gear mechanism, 42 Final shaft, 43 Chain sprocket, 44
chain. 51 ... Engine shroud, 52 ... Suction fan cover,
53 ... Cooling air inlet. 6 ... Crank case, 61 ... Left case part, 62 ... Case right part, 63 ... Case output part, 64 ... Left crank case cover, 65,66 ... Mating surface, 67 ... Engine hanger boss. D: Step of the mating surface.

Claims (1)

(57) [Scope of request for utility model registration] 1. A crankshaft, which is an input shaft of a continuously variable V-belt transmission, and a driven shaft, which is an output shaft of the continuously variable V-belt transmission,
In a crankcase for an internal combustion engine, which is supported by a crankcase and a gear shaft of a reduction gear mechanism having the driven shaft as an input shaft is supported by the crankcase, the crankshaft includes one side of the case and the other side of the case. The driven shaft and the gear shaft of the reduction gear mechanism are supported by the case output portion and the case one side located on the same side as the case other side with respect to the case one side, The mating surface of the case one side and the case output portion is formed to be more stepwise in the case other side than the mating surface of the case one side and the case other side, and the case other side is The crankcase for an internal combustion engine, wherein the case output section is disposed in contact with one side of the case.