JPH0411430B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine unit for a motorcycle that integrates an engine and a V-belt automatic transmission.

[Prior art]

Small motorcycles called family bikes use so-called unit swing engines, which integrate an engine and a V-belt automatic transmission, with a rear wheel attached to the rear end of the V-belt automatic transmission. unit is used.

This engine unit has a driven shaft parallel to the crankshaft in the transmission case connected to the engine crankcase, rotatably supports the driven pulley on this driven shaft, and connects the driven pulley and driven shaft to the driven shaft. The driven pulley is connected via a centrifugal clutch that allows power transmission only from the pulley side, and a V-belt is spanned between this driven pulley and a driving pulley directly connected to the crankshaft.

By the way, this driven pulley is equipped with a cylindrical boss that is attached to the outer periphery of the driven shaft, and two parts of this boss that are spaced apart in the axial direction are rotatable on the outer periphery of the driven shaft via ball bearings. It is pivoted on. In this case, conventionally, in order to position the ball bearing, the driven shaft is composed of a large diameter part and a small diameter part, and one ball bearing is brought into contact with the stepped part that is the boundary between the large diameter part and the small diameter part. At the same time, a collar is interposed between both of these bearings, and in this state, by screwing a nut into the small diameter part, the two ball bearings are sandwiched and fixed between this nut and the stepped part. is being carried out.

[Problem to be solved by the invention]

However, when the boss portion of the driven pulley is supported via two ball bearings, the outer diameter of the ball bearings is considerably larger than the outer diameter of the driven shaft, so the boss portion itself becomes thick and large. For this reason, when attempting to secure a sufficient range of change in the winding diameter of the V-belt, that is, a sufficient gear ratio, the outer diameter of the driven pulley becomes large, resulting in a problem that hinders the downsizing of the V-belt automatic transmission and, by extension, the overall engine unit. be.

In addition, a special collar is required to maintain a constant distance between the two bearings, which increases the number of parts, which not only requires time and effort to disassemble and reassemble, but also causes a disadvantage in terms of weight. There is a problem.

The present invention was made based on these circumstances, and the diameter of the boss portion of the driven pulley can be reduced, and the driven pulley can be downsized without reducing the range of change in the winding diameter of the V-belt. The purpose of the present invention is to provide an engine unit for a motorcycle that does not require special collars for positioning the bearings, and also allows easy machining of the boss part of the driven pulley and installation of the bearings. do.

[Means to solve the problem]

Therefore, in the present invention, the transmission case includes
One end of a driven shaft parallel to the engine crankshaft is rotatably supported, a driven pulley is rotatably supported around the outer circumference of this driven shaft, and this driven pulley and driven shaft are connected via a centrifugal clutch. At the same time, a V-belt is spanned between this driven pulley and a driving pulley that rotates integrally with the crankshaft,
By changing the groove width of each pulley according to the rotational speed of the crankshaft, the V
In a motorcycle engine unit that performs continuously variable speed by automatically changing the winding diameter of a belt, the driven shaft has a large diameter portion and a small diameter portion coaxially connected to the large diameter portion, and , the driven pulley is provided with a hollow cylindrical boss portion having a through hole through which the large diameter portion and the small diameter portion of the driven shaft are passed, and an outer periphery of one end of the boss portion on the large diameter portion side of the driven shaft,
The driven pulley has a movable plate and a fixed plate for forming a V-shaped groove around which the V-belt is wound, and the boss portion of the driven pulley has both axial ends connected to the driven shaft via bearings. The bearings are rotatably supported on the outer periphery, and among these bearings, the bearings inside the movable plate and the fixed plate are positioned as needle bearings on the large diameter portion of the driven shaft, and the other bearings are positioned as ball bearings on the small diameter portion. The inner ring of this ball bearing is brought into contact with the stepped part at the boundary between the large diameter part and the small diameter part, while the through hole of the boss part is opened sequentially from one end to the other end. The centrifugal plate of the centrifugal clutch is fixed to the other end of the small-diameter side of the driven shaft in this boss part, and the power transmission is intermittent through a weight provided on the centrifugal plate. The present invention is characterized in that a side member is attached to the outer periphery of the small diameter portion together with the ball bearing, and the inner ring of the ball bearing is inserted and fixed between the output side member and the stepped portion on the driven shaft.

[Effect]

According to this configuration, the outer diameter of the outer ring in contact with the boss of the needle bearing located inside the driven pulley is smaller than that of a ball bearing, so the diameter of the boss can be made smaller by that amount. The diameter of the driven pulley can be reduced while ensuring a sufficient range of change in the belt winding diameter. In this case, if a ball bearing with a larger outer diameter than a needle bearing is placed on the small diameter part of the driven shaft, the diameter of the boss can be made smaller over the entire length, making it possible to reduce the weight of the driven pulley. At the same time, the wall thickness on the small-diameter side of the post section does not become thinner locally, which is advantageous in terms of strength.

Further, since the stepped portion on the driven shaft can be used for axial positioning of the ball bearing, there is no need for a special collar as in the prior art, and the number of parts can be reduced and the structure can be simplified accordingly.

Moreover, the through hole of the boss part through which the driven shaft passes,
Since the inner diameter of the driven shaft gradually increases from the large diameter side to the small diameter side, the through hole can be machined all at once from the other end side of the boss portion. Therefore, when machining a through hole, there is no need to perform machining from both sides of the boss in the axial direction, which eliminates the need for troublesome and time-consuming work such as changing the position of the boss. , the boss part can be easily processed.

Furthermore, since the needle bearing, which is elongated in the axial direction of the through hole, is located at one end of the boss portion, it can be mounted from the opening at one end of the through hole. Therefore, when installing a needle bearing that is elongated in the axial direction of the through hole into the through hole, the length of pushing the needle bearing into the through hole can be kept short.
Accordingly, the contact resistance generated between the needle bearing and the through hole is reduced, and the work of assembling the needle bearing into the boss portion can be easily performed.

〔Example〕

An embodiment of the present invention will be described below based on the drawings in which the present invention is applied to a scooter type motorcycle.

Reference numeral 1 in FIG. 3 is a pipe frame constituting the vehicle body, and a down tube 3 extending downward is connected to a head pipe 2 located at the front end of the pipe frame. A main pipe 4 extending rearward is connected to the lower end of the down tube 3. The rear end portion of the main pipe 4 is raised upward, and the upper portion of this rising portion 5 constitutes a seat rail 6 extending rearward. A steering shaft 7 is pivotally supported on the head pipe 2, and a front wheel 9 is supported at the lower end of the steering shaft 7 via a front fork 8.
A handle 7a is attached to the upper end of the steering shaft 7.

Incidentally, a front end portion of an engine unit 10 is swingably supported on the rising portion 5 of the frame 1 via a support shaft 11. Details of this engine unit 10 are shown in FIGS. 1 and 2, and this engine unit 10 will be explained below.

That is, this engine unit 10 is configured as an integral structure of a forced air-cooled engine 12 and a transmission case 14 extending rearward from the left side of a crankcase 13 of this engine 12. It is suspended by a shock absorber 15 installed between it and the upper seat rail 6.
The crankcase 13 of the engine 12 is divided into two parts, a left case 13a and a right case 13b.
A crankshaft 17 extending along the left and right direction of the vehicle body is supported via the shaft. Further, an upright cylinder 18 is provided on the upper surface of the crankcase 13.
A piston 19 within this cylinder 18 is connected to the crankshaft 17 via a connecting rod 20.
A flywheel magneto 21 and a fan 22 are attached to one end of the crankshaft 17. The fan 22 is for forced air cooling of the cylinder 18 and cylinder head 23 of the engine 12, and the cylinder 18 and cylinder head 23 are covered by a shroud 24. The shroud 24 has an intake port 25 facing the fan 22.
and an exhaust port 26, and the outside air sucked in from the intake port 25 by the rotation of the fan 22 flows around the cylinder 18 and the cylinder head 23, and then is exhausted to the outside through the exhaust port 26. .

The left case 13a of the crankcase 13 and the side opening of the transmission case 14 connected thereto are covered by a case cover 30, and between these cases 13a, 14 and the case cover 30 is a transmission chamber 31. is formed. A gear chamber 70 separated from the transmission chamber 31 is formed at the rear of the transmission chamber 31. The gear chamber 70 is a gear case 7 integrally formed inside the transmission case 14.
0a and the case cover 3 of this gear case 70a
The gear chamber 70 is configured with a gear case cover 41 that closes the opening on the 0 side.
It is located on the inside surrounded by the mating surface between the case cover 30 and the case cover 30.

Further, a belt type automatic transmission 32 is housed within the transmission chamber 31. This automatic transmission 32
To explain, the left end portion of the crankshaft 17 is introduced into the transmission chamber 31, and a drive pulley 33 is attached to the outer periphery of the left end portion. The drive pulley 33 includes a fixed plate 34a and a movable plate 34b that rotate together with the crankshaft 17. The movable plate 34b is provided so as to be movable toward and away from the fixed plate 34a. V between
A groove 35 is formed. And the movable plate 34b
A support plate 36 that rotates together with the crankshaft 17 is provided at a position adjacent to the crankshaft 17.
A centrifugal weight 37 is provided between 6 and the movable plate 34b. When this centrifugal weight 37 is displaced radially outward due to centrifugal force accompanying an increase in the rotational speed of the movable plate 34b, the movable plate 34b is pushed out in a direction approaching the fixed plate 34a, and the V-shaped groove 35
The width of the groove is reduced.

Further, a crankshaft 17 is provided at the rear end of the transmission chamber 31.
A driven shaft 40 is supported in parallel with. Driven shaft 4
0 is the above gear case cover 41 and case cover 3
0, and both ends thereof are rotatably supported via bearings 42 and 43, respectively. A driven pulley 44 is attached to the outer periphery of this driven shaft 40. Driven pulley 44
includes a hollow cylindrical boss portion 45 having a through hole 45a through which the driven shaft 40 passes. On the outer periphery of one end of the boss portion 45 on the gear case cover 41 side, there is a fixed plate 46a that rotates together with the boss portion 45.
A movable plate 46b is provided which can move toward and away from the fixed plate 46a. The movable plate 46b forms a V-shaped groove 47 with the fixed plate 46a, and is biased by a coil spring 49 in a direction approaching the fixed plate 46a, that is, in a direction that reduces the groove width of the V-shaped groove 47. An endless V-belt 48 is wound between the V-shaped groove 47 of the driven pulley 4 and the V-shaped groove 35 of the drive pulley 33. Therefore, as described above, as the rotational speed of the crankshaft 17 increases, the groove width of the V-shaped groove 35 of the drive pulley 33 is reduced and the V-belt 48 is pushed outward in the radial direction. Since the V-belt 48 is pulled, the movable plate 46b moves in a direction away from the fixed plate 46a against the biasing force of the coil spring 49, and the V-shaped groove 4
7 groove width is widened. As a result, the winding diameter of the V-belt 48 around each pulley 33, 44 changes, and the gear ratio changes continuously and steplessly.

By the way, as shown in FIG. 1, the driven shaft 40 passing through the boss portion 45 of the driven pulley 44 is composed of a large diameter portion 51 supported by the gear case 41 and a small diameter portion 52 supported by the case cover 30. be done.
The large diameter portion 51 and the small diameter portion 52 are coaxial, and a stepped portion 53 extending in the radial direction is formed at the boundary portion thereof. Then, the boss portion 4
5 extends over a large diameter portion 51 and a small diameter portion 52,
One end of the through hole 45a is pivotally supported by the large diameter portion 51 via a needle bearing 54, and the other end of the through hole 45a is pivotally supported by the small diameter portion 52 via a ball bearing 55. The needle bearing 54 is located inside the rotating plate 46a and the movable plate 46b,
The outer ring 54a, which is adapted to receive the load transmitted to the driven shaft 40 side through the fixed plate 46a and the movable plate 46b, fits into the inner surface of the boss portion 45.
The outer diameter of the outer ring 55a is smaller than that of the outer ring 55a. As for the ball bearing 55,
The inner ring 55b is fitted onto the outer periphery of the small diameter portion 52, and one end of the inner ring 55b is in contact with the stepped portion 53.

Further, the through hole 45a of the boss portion 44 has the smallest diameter first through hole 45a into which the outer ring 54a of the needle bearing 54 fits.
a hole 45b, a second hole 45c having a larger diameter than the first hole 45b, and a second hole 45c.
The third hole 45d has a larger diameter than that of the third hole 45d and the outer ring 55a of the ball bearing 55 fits therein.
It consists of Each of these holes 45b, 45c,
45d are coaxial with each other, and the first hole 45c is opened at one end surface of the boss section 45, and the third hole 45d is opened at the other end surface of the boss section 45. And the second hole 45c
A step portion 56 extending in the radial direction is formed at the boundary between the third hole portion 45d and the third hole portion 45d, and one end of the outer ring 55a is in contact with this step portion 56.

The driven pulley 44 and the driven shaft 40 are connected via a centrifugal clutch 60. The centrifugal clutch 60 includes a clutch housing 61 having an outer diameter approximately equal to that of the driven pulley 44. This clutch housing 61 is integrally attached to the small diameter part 52 by attaching a cylindrical bearing part 62 provided at the center of rotation to the outer periphery of the small diameter part 52 and tightening it with a nut 63 screwed in from the case cover 30 side. Fixed. The bearing portion 62 of the clutch housing 61 is in contact with the inner ring 55b of the ball bearing 55, and the inner ring 55b is inserted between the stepped portion 53 and the ball bearing 55 is positioned in the axial direction. I am doing it.

A centrifugal plate 64 is arranged inside the clutch housing 61. The centrifugal plate 64 is fixed to the boss portion 45 of the driven pulley 44, and a centrifugal weight 65 is provided on the outer periphery of the centrifugal plate 64 so as to be in contact with the inner circumferential surface of the clutch housing 61 in a movable manner. Therefore, when the rotational speed of the driven pulley 44 reaches a predetermined value, the centrifugal weight 65 is displaced radially outward based on the centrifugal force and comes into contact with the clutch housing 61, and the frictional force accompanying this contact causes the driven pulley 44 to rotate. The rotation is transmitted to the driven shaft 40. From this, in the case of this embodiment, the clutch housing 61 constitutes the output side member.

On the other hand, a rear wheel 73 that supports a rear wheel 79 is pivotally supported at the rear end of the transmission case 14 via a bearing 74 . The rear wheel 73 is located coaxially with the driven shaft 40, and both shafts 40, 73
The mutually opposing ends of are introduced into the gear chamber 70. This gear chamber 70 accommodates a speed reducer 71 that reduces the rotation of the driven shaft 40 and transmits it to the rear axle 73. The reducer 71 includes an intermediate shaft 72 that is parallel to the driven shaft 40 and the rear wheel 73,
The intermediate shaft 72 is rotatably supported astride the transmission case 14 and the gear case cover 41. On the intermediate shaft 72 are a decreasing gear 75 and a decreasing gear 7.
6 is provided, the reducing gear 75 is connected to the small gear 77 provided at the introduction end of the driven shaft 40, and the reducing gear 76 is connected to the output gear 7 which rotates integrally with the rear axle 73.
8 are interlocked with each other. Therefore, the driven shaft 4
The zero rotation is transmitted to the rear wheel 79 after being decelerated in two stages by the meshing of the small gear 77, the large reduction gear 75, and the small reduction gear 76 and the output gear 78.

Further, a kick shaft 80 for starting is provided between the crankshaft 17 and the driven shaft 40. The kick shaft 80 is rotatably supported astride the transmission case 14 and the case cover 30, and a kick arm 82 having a kick pedal 81 is attached to its outwardly extending end. A sector gear 83 is rotatably supported on the kick shaft 80, and this sector gear 83 meshes with a helical spline gear 85 provided on the starting shaft 84. Starting shaft 8
4 is provided with a dog gear 86 movable in the axial direction, and this dog gear 86 is connected to the crankshaft 1.
It is adapted to mesh with another dog gear 87 provided on the 7 side. Therefore, when the kick arm 82 is stepped down and the kick shaft 80 is rotated, the fan-shaped gear 83 is rotated and the helical spline gear 8 is rotated.
5 toward the crankshaft 17, the dog gears 86 and 87 mesh with each other, and the crankshaft 17
is rotated.

Note that reference numeral 88 in the figure is a torsion coil spring that biases the fan-shaped gear 83 in the return direction.

According to such a configuration, the needle bearing 54 that supports the boss portion 45 of the driven pulley 44 inside the fixed plate 46a and the movable plate 46b supports the boss portion 45 of the driven pulley 44.
The outer diameter of the outer ring 54a in contact with the inner surface of the ball bearing 5
5, the diameter of the boss portion 45 into which the outer ring 54a fits can be made smaller accordingly. Therefore, the driven pulley 44 can be made smaller while ensuring a sufficient change range in the winding diameter of the V-belt 48 on the driven pulley 44, that is, a shift width.

However, when the diameter of the inner circumference regulated by the driven shaft 40 is the same, the ball bearing 55, in which the outer diameter of the outer ring 55a is larger than that of the needle bearing 54, is By disposing it on the outer periphery of the ball bearing 55, the diameter of the outer ring 55a of the ball bearing 55 can be reduced by the difference in level between the small diameter portion 52 and the large diameter portion 51. Therefore, the outer diameter of the outer ring 55a of the ball bearing 55 is approximately the same as the outer ring 54a of the needle bearing 54, and the diameter of the boss portion 45 can be reduced over the entire length. Therefore, the weight of the driven pulley 44 can be reduced, and the thickness of the boss portion 45 does not become locally thinner at the end on the small diameter portion 52 side, which is advantageous in terms of strength.

Furthermore, the through hole 45a of the boss portion 45 through which the driven shaft 40 passes has an inner diameter that gradually increases from one end where the needle bearing 54 is mounted to the other end where the ball bearing 55 is mounted. Since it changes in three steps, the through hole 45a can be processed all at once from the other end side of the boss portion 45. Therefore, when machining the through hole 45a, there is no need to perform machining from both sides of the boss portion 45 in the axial direction.
Changing the posture eliminates the need for troublesome and time-consuming work, making processing easier.

Moreover, the needle bearing 54 is installed in the first hole 45b of the through hole 45a, and the needle bearing 54 is attached to the first hole 45b of the through hole 45a.
Since it is located at the opening at one end, the needle bearing 54 can be mounted from the opening at one end of the through hole 45a.

Therefore, when the needle bearing 54, which is elongated in the axial direction of the through hole 45a, is installed in the through hole 45a, the length of pushing the needle bearing 54 into the through hole 45a can be kept short. Therefore, the needle bearing 54 and the through hole 45
The contact resistance generated between the needle bearing 54 and the boss portion 45 is reduced, and the work of assembling the needle bearing 54 into the boss portion 45 can be easily performed.

In addition, the ball bearing 55 that supports the other end of the boss portion 45 is fixed by being inserted between the step portion 53 on the driven shaft 40 and the clutch housing 61, so that the ball bearing 55 supports the step portion 53 on the driven shaft 40 and the clutch housing 61. 55 can be used for positioning. This eliminates the need for special collars as in the prior art, making it possible to simplify the structure and reduce the weight of the mounting portion of the driven pulley 44.

〔Effect of the invention〕

According to the present invention described in detail above, since the diameter of the boss portion supported on the driven shaft can be reduced over the entire length, the driven pulley can be made smaller in diameter while ensuring a sufficient range of change in the winding diameter of the V-belt. can be converted into
At the same time, the weight of the driven pulley is reduced, and the thickness of the boss portion does not become locally thinner on the small diameter portion side, which is advantageous in terms of strength.

Further, since the stepped portion on the driven shaft can be used for positioning the ball bearing, there is no need for special collars as in the past, and the structure of the attached portion of the driven pulley can be simplified and lightened.

In addition, the inner diameter of the through hole through which the driven shaft passes increases gradually from one end where the needle bearing is installed to the other end where the ball bearing is installed. Processing can be performed all at once from the other end side of the boss portion. Therefore, when machining a through hole, there is no need to perform machining from both sides of the boss in the axial direction, so there is no need to carry out the troublesome and time-consuming work of changing the position of the boss during machining. Therefore, processing can be performed more easily.

At the same time, when a needle bearing having a large contact area with the through hole is mounted in the through hole, the length of pushing the needle bearing into the through hole can be kept short. Therefore, the contact resistance generated between the needle bearing and the through hole is reduced, and the work of assembling the needle bearing into the boss portion can be easily performed.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a sectional view of an engine unit, FIG. 2 is a plan view of the engine unit, and FIG. 3 is a side view of a scooter type motorcycle. 10...Engine unit, 12...Engine, 1
7... Crankshaft, 33... Drive pulley, 40... Driven shaft, 44... Driven pulley, 45... Boss portion, 45a...
Through hole, 46a...fixed plate, 46b...movable plate, 47
...V-shaped groove, 48...V belt, 51...large diameter part, 52
...Small diameter part, 53...Step part, 54...Needle bearing,
55...Ball bearing, 60...Centrifugal clutch, 61...
Output side member (clutch housing), 64...Centrifugal plate, 65...Weight (centrifugal weight).

Claims (1)

[Scope of Claims] 1. One end of a driven shaft parallel to the engine crankshaft is rotatably supported in the transmission case, and a driven pulley is rotatably supported on the outer periphery of this driven shaft. A pulley and a driven shaft are connected via a centrifugal clutch, and a V-belt is spanned between this driven pulley and a driving pulley that rotates integrally with the crankshaft, and each pulley is rotated according to the rotational speed of the crankshaft. In a motorcycle engine unit that performs continuously variable transmission by automatically changing the winding diameter of the V-belt around these pulleys by changing the groove width of the The driven pulley includes a hollow cylindrical boss portion having a through hole through which the large diameter portion and the small diameter portion of the driven shaft are passed, and a driven shaft in the boss portion. The driven pulley has a movable plate and a fixed plate provided on the outer periphery of one end of the large-diameter side to form a V-shaped groove around which the V-belt is wound. Both ends are rotatably supported on the outer periphery of the driven shaft via bearings, and among these bearings, the bearings inside the movable plate and the fixed plate are positioned as needle bearings on the large diameter portion of the driven shaft. At the same time, another bearing is positioned as a ball bearing on the small diameter part, and the inner ring of this ball bearing is brought into contact with the stepped part at the boundary between the large diameter part and the small diameter part, while the through hole of the boss part is The inner diameter of the centrifugal clutch is gradually increased from one end to the other end, and the centrifugal plate of the centrifugal clutch is fixed to the other end of the driven shaft on the small diameter side of the boss. An output side member to which power transmission is interrupted and interrupted via a weight is attached to the outer periphery of the small diameter portion together with the ball bearing, and the inner ring of the ball bearing is mounted between the output side member and the stepped portion on the driven shaft. A motorcycle engine unit characterized by being clamped and fixed.