JP2002130406A - Automatic transmission for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a transmission and enhance the transmission torque by surely cooling a dry type belt. SOLUTION: A fixed sheave 25 and a movable sheave 26 of a driving pulley 21 are formed of aluminum alloy respectively. The dry type belt 24 formed of a lot of elements 42 and rings 43 is wound around the driving pulley 21 and a driven pulley 23. The element 42 is formed of synthetic resin. The rings 43 are so constituted as to connect the respective elements 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission for a vehicle mounted on, for example, a scooter.

[0002]

2. Description of the Related Art Conventionally, an automatic transmission of a motorcycle such as a scooter has been incorporated in a transmission case of a unit swing type power unit. A drive pulley is mounted on a crankshaft of an engine, and an output of a rear wheel side is provided. A driven pulley is mounted on the shaft, and a V-belt is wound around both pulleys. The drive pulley and the driven pulley are each composed of a fixed sheave that is prevented from moving in the axial direction and a movable sheave that can move in the axial direction.

In this type of automatic transmission, the winding diameter of the V-belt changes according to the number of revolutions of a crankshaft by a speed change means provided on a drive pulley.
The transmission means includes a cam surface formed at one end in the axial direction of the movable pulley so as to extend in the radial direction, and a centrifugal weight that is in contact with the cam surface and moves in the radial direction of the movable sheave. According to this speed change means, the centrifugal weight moves outward in the radial direction of the movable sheave due to the centrifugal force, so that the movable sheave approaches the fixed sheave and the winding diameter of the drive pulley increases.

[0004]

Generally, a rubber V-belt is used for a small torque of a motorcycle or the like. However, in the conventional automatic transmission for a vehicle configured as described above, the V-belt is not used. There is also a limit in increasing the transmission torque due to slip. In order to increase the transmission torque, it is conceivable to use a metal belt used for a transmission (CVT) of an automobile instead of the rubber V-belt. This CVT belt has a structure in which a number of metal elements are connected by a ring.

However, the CVT belt must be operated in oil because the contact portion between the metal element and the pulley must be lubricated, and further increases the frictional force reduced by lubrication. Therefore, the movable pulley must be pressed with hydraulic pressure. For this reason, if this CVT belt is used in a transmission for a motorcycle, the unit swing type power unit becomes large and the bank angle becomes narrow. Further, since the hydraulic pump for generating the hydraulic pressure must be driven by the engine, fuel consumption is reduced accordingly, and the engine used for a scooter or the like has a smaller output than an automobile engine. The running performance is also reduced, including the increase in weight.

The present inventors have attempted to reduce the size of the power unit and improve the transmission torque by forming a dry automatic transmission by replacing the metal element of the CVT belt with a synthetic resin element. I'm thinking about that.
However, in order to form such a dry automatic transmission, there is a problem in cooling a synthetic resin belt whose temperature increases due to friction. This is because the transmission must be housed in the transmission case of the unit swing type power unit, and the space formed around the transmission is narrower than when mounted on an automobile. Failure to cool the belt significantly reduces the durability of the belt.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem, and it is intended to surely cool a dry belt composed of a synthetic resin element and a ring, to reduce the size of a transmission and to reduce the transmission torque. It aims at improvement.

[0008]

In order to achieve this object, an automatic transmission for a vehicle according to the present invention has a fixed sheave and a movable sheave of a drive pulley formed of an aluminum alloy, respectively. , A dry belt comprising a number of elements formed of a synthetic resin and a ring connecting the elements. According to the present invention, the heat of the synthetic resin element is easily transmitted to the driving pulley, and is radiated to the surrounding space by the rotation of the driving pulley.

According to a second aspect of the present invention, there is provided an automatic transmission for a vehicle according to the first aspect of the invention, wherein a centrifugal roller is attached to a cam surface formed on a movable sheave of a driving pulley. The transmission means is constituted by contacting the outer peripheral portion of the centrifugal roller and the element of the dry belt with the same type of synthetic resin material. According to the present invention, both the centrifugal roller and the element are less likely to be deformed, and the heat dissipation is further improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic transmission for a vehicle according to the present invention will be described below in detail with reference to FIGS. Here, an embodiment in which the vehicle automatic transmission according to the present invention is applied to a scooter type motorcycle will be described. FIG. 1 is a side view of a scooter type motorcycle equipped with a vehicle automatic transmission according to the present invention, FIG. 2 is an enlarged sectional view showing a drive pulley portion of a unit swing type power unit, and FIG. 3 is a unit swing type power unit. It is sectional drawing which expands and shows the driven pulley part of a unit. 4 is a cross-sectional view of the dry belt, FIG. 5 is a cross-sectional view taken along line VV in FIG. 4, and FIG.

In these figures, what is indicated by reference numeral 1 is a scooter type motorcycle according to this embodiment. The motorcycle 1 has a configuration in which a rear wheel 2 is driven by a unit swing type power unit 3. In FIG. 1, reference numeral 4 denotes a front wheel, 5 denotes a front fork, 6 denotes a steering handle, 7 denotes a body frame, 8 denotes a seat, 9 denotes a storage box below the seat, 10 denotes a helmet stored in the storage box 9. , 11 indicate a fuel tank.

The unit swing type power unit 3
Is an automatic transmission 13 stored in the transmission case 12 and described later.
Except that the driving pulley and the belt are different, a structure equivalent to a conventionally well-known one is employed. The power unit 3 is provided with an engine 14 at a front end portion of the vehicle body so that a cylinder extends forward of the vehicle body. The front portion on which the engine 14 is provided is swingable vertically by the support shaft 15 on the vehicle body frame 7. And a transmission case 12 extending rearward from the vehicle body from an end of the engine 14 on the vehicle body left side.
A rear wheel 2 is rotatably provided at the rear end of the vehicle. A cushion unit 16 is interposed between the rear end of the transmission case 12 and the vehicle body frame 7.

As shown in FIGS. 2 and 3, the transmission case 12 includes a right half portion 12a integrally formed with a crankcase 14a of the engine 14, and an opening portion (an end portion on the left side of the vehicle body) of the right half portion 12a. ) Is formed by the left half portion 12b that closes the upper portion. An outer cover 12c for soundproofing is attached to the left half portion 12b. The automatic transmission 13 accommodated in the transmission case 12 includes a drive pulley 21 (see FIG. 2) mounted on the crankshaft 17 of the engine 14.
It is constituted by a driven pulley 23 mounted on an output shaft 22 (see FIG. 3) at the rear end of the transmission case, and a dry belt 24 wound around these pulleys 21 and 23.

The drive pulley 21 is formed by a fixed sheave 25 and a movable sheave 26,
Have been supported. The sheaves 25 and 26 are made of an aluminum alloy. The fixed sheave 25 is integrally formed with a blower fin 25a. The movable sheave 26 is provided with a cam plate 27 adjacent to the movable sheave 26 and a transmission means 28. Surface 26a and guide 2 constituting
6b. In the transmission case 12 according to the present embodiment, when the blower fins 25a rotate together with the fixed sheave 25, outside air is sucked into the transmission case 12 from an outside air suction port (not shown) at the front of the transmission case. The air in the transmission case 12 is formed to be exhausted from an exhaust port (not shown).

The fixed sheave 25 is fixed to the crankshaft 17, and the movable sheave 26 is supported by a sleeve 29, which is spline-fitted to the crankshaft 17, by a bearing 30 so as to be movable in the axial direction. A cam plate 27 adjacent to the movable sheave 26 is fixed to the crankshaft 17 and connected to the guide 26b of the movable sheave 26 via a slider 27a. In FIG. 2, a kick starter device indicated by reference numeral 31 located on the left side of the vehicle body with respect to the fixed sheave 25 is shown.

The transmission means 28 has a structure in which a plurality of centrifugal rollers 32 are sandwiched between the cam surface 26a of the movable sheave 26 and the cam plate 27. The centrifugal roller 32 is formed in a cylindrical shape by a metal cylinder 32a and a synthetic resin outer cylinder 32b provided on the outer periphery of the cylinder 32a. As the synthetic resin material forming the outer cylinder 32b, a material having heat resistance, abrasion resistance and self-lubricating property is adopted. In this embodiment, 4.6 nylon is used.

When the number of revolutions of the engine 14 increases, the centrifugal roller 32 moves radially outward of the movable sheave 26 by centrifugal force, so that the movable sheave 26 moves to the left as shown by a two-dot chain line in FIG. And the winding diameter of the drive pulley 21 increases. Conversely, when the rotation speed of the engine 14 decreases, the movable sheave 26 moves to the right, and the winding diameter of the drive pulley 21 decreases.

The driven pulley 23 has a well-known structure and is rotatably supported on the output shaft 22 via bearings 33 and 34 and a sleeve 35 as shown in FIG. It is composed of a fixed sheave 36 and a movable sheave 37 supported on the sleeve 35 so as to be movable in the axial direction. In FIG. 3, the upper side of the output shaft 22 is illustrated in a state during high-speed operation, and the lower side is illustrated in a state during low-speed operation including idling.

The fixed sheave 36 and the movable sheave 37 of the driven pulley 23 are made of steel. An input member 38a of a centrifugal clutch 38 is fixed to an end of the sleeve 35 on the left side of the vehicle body, and a compression coil spring 39 for pressing the movable sheave 37 toward the fixed sheave 36 is provided between the input member 38a and the movable sheave 37. I am armed. In the centrifugal clutch 38, the output member 38b is fixed to the shaft end of the output shaft 22, and the rotation of the sleeve 35 (the rotation of the driven pulley 23) is transmitted to the output shaft 22 during low rotation such as idling. The rotation of the sleeve 35 is transmitted to the output shaft 22 during other high-speed running. The output shaft 22 is connected to an output gear 22a formed at the right end of the vehicle body via an intermediate gear (not shown) to the reduction gear 41 of the rear wheel shaft 40.

As shown in FIGS. 4 and 5, the dry belt 24 includes a number of elements 42 and two rings 43 connecting the elements 42 to each other. The element 42 is formed in a horizontal H-shape in cross section by a synthetic resin. This element 42
Is the same as the material forming the outer cylinder 32b of the centrifugal weight 32, and uses 4.6 nylon. Also, a horizontal H-shaped element 4
4 out of the four arms 42a to 42d formed in FIG.
The two arms 42a, 42b located on the upper side
As shown in FIG. 5, a ridge 44 projecting downward and having a semicircular cross section is formed at the lower portion, and the other two arms 42c and 4
2d forms a projection 45 having a semicircular cross section projecting upward at the upper part.

The ring 43 includes a plurality of cords 46 formed of aramid fiber, a covering rubber 47 for holding the cords 46 in a line in a horizontal direction, and covers an outer surface of the rubber 47. It is formed by a canvas 48 and fits into a concave portion 49 formed to open laterally on the side of the element 42. The rubber 47 and the canvas 48 form an element 42.
It is formed of a material having heat resistance equivalent to 6 nylon. Further, the rubber 47 is provided with two ridges 44, 4 formed on the four arms 42a to 42d of the element 42.
A large number of concave grooves 47a and 47b to be fitted into the respective grooves 5 are arranged in parallel.

In the automatic transmission 13 configured as described above, when the engine 14 starts, the drive pulley 21 rotates together with the crankshaft 17, and this rotation is performed by the dry belt 2.
4 to the driven pulley 23. Dry belt 2
When the belt 4 rotates, the temperature of the dry belt 24 rises due to frictional heat due to friction with the driving / driven pulleys 21 and 23 and bending of the belt. The friction heat is transmitted to the transmission case 12.
During the rotation of the dry belt 24 inside the case, the dry belt 24 is dissipated into the air inside the case, and is transmitted to the driving pulley 21 and the driven pulley 23 from the contact portion by conduction.

In the automatic transmission 13, since the fixed sheave 25 and the movable sheave 26 of the drive pulley 21 are each formed of an aluminum alloy, the heat of the element 42 of the dry belt 24 is easily transmitted to the drive pulley 21. Therefore, the heat of the dry belt 24 can be efficiently dissipated from the driving pulley 21 to the surrounding space. Therefore, the hydraulic mechanism can be omitted as compared with the case where a metal belt is used, so that downsizing can be achieved and the transmission torque can be improved as compared with the case where a conventional V-belt is used.

FIG. 6 shows the difference in slip ratio between the case where the dry belt 24 according to the present invention is used and the case where the V belt is used. In FIG. 6, the case where the dry belt 24 is used is shown by a solid line, and the case where a rubber V-belt is used is shown by a broken line. As is clear from FIG.
m, the dry belt 24 has a lower V
The slip ratio is lower than that of the belt. For this reason, heat generation of the belt is suppressed, and the durability of the coating rubber is improved,
Higher efficiency and longer life than rubber V-belts.

Further, since the outer cylinder 32b of the centrifugal roller 32 of the automatic transmission 13 and the element 42 of the dry belt 24 are formed of the same synthetic resin material, both of them are less likely to be deformed, so that heat is radiated more. The nature becomes high. The element 42 of the dry belt 24 and the outer cylinder 32b are used to prevent abrasion due to slippage caused by the engagement and disengagement between the dry belt 24 and the pulley, and wear caused by slippage between the pulley and the centrifugal roller 32. Is formed of the same kind of synthetic resin material, the pulley can be made of an aluminum alloy, the heat of the dry belt 24 can be radiated from the pulley, and the durability of the dry belt 24 can be improved. Further, since the element 42 of the dry belt 24 is made of an integral resin, the belt can be made lighter, and in a high-speed driving such as a motorcycle, the centrifugal force of the belt is reduced. Sufficient speed change and torque transmission are possible with thrust of 32. Therefore, the transmission can be downsized, and the object can be achieved without impairing the function of the motorcycle. Moreover, when the centrifugal roller 32 becomes lighter, the centrifugal roller 32 becomes lighter.
The gears can be smoothly shifted even if they rotate at high speed, and the gears can be easily shifted.

[0026]

As described above, according to the present invention, the heat of the synthetic resin element is easily transmitted to the driving pulley, and is radiated to the surrounding space by the rotation of the driving pulley. For this reason, the dry belt made of the synthetic resin element and the ring can be reliably cooled, so that it is possible to provide an automatic transmission for a vehicle that is small and has a large transmission torque.

According to the second aspect of the present invention, both the centrifugal roller and the element are hardly deformed, so that the heat dissipation is further improved.

[Brief description of the drawings]

FIG. 1 is a side view of a scooter type motorcycle equipped with a vehicle automatic transmission according to the present invention.

FIG. 2 is an enlarged sectional view showing a drive pulley portion of the unit swing type power unit.

FIG. 3 is an enlarged sectional view showing a driven pulley portion of the unit swing type power unit.

FIG. 4 is a sectional view of a dry belt.

FIG. 5 is a sectional view taken along line VV in FIG.

FIG. 6 is a graph showing a relationship between a shaft torque and a slip ratio.

[Explanation of symbols]

13 automatic transmission, 21 driving pulley, 23 driven pulley, 24 dry belt, 25 fixed sheave, 26 movable sheave, 28 transmission means, 32 centrifugal roller, 32b
Outer cylinder, 42 ... element, 46 ... core wire, 47 ... rubber for covering, 49 ... concave part.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F16H 55/56 F16H 55/56 57/02 321 57/02 321D 57/04 57/04 C

Claims (2)

[Claims] 1. A drive pulley driven by an engine and a driven pulley connected to the drive pulley via a belt, on a drive wheel side, are movable in an axial direction with a fixed pulley which is prevented from moving in the axial direction. In a vehicular automatic transmission formed by a driven pulley, a fixed sheave and a movable sheave of the drive pulley are each formed of an aluminum alloy, and a large number of elements formed of a synthetic resin are formed on the drive pulley and the driven pulley, An automatic transmission for a vehicle, wherein a dry belt comprising a ring connecting each element is wound around the dry belt. 2. The automatic transmission for a vehicle according to claim 1, wherein the transmission means is constituted by bringing a centrifugal roller into contact with a cam surface formed on a movable sheave of a driving pulley, and an outer peripheral portion of the centrifugal roller; An automatic transmission for a vehicle, wherein the elements of the dry belt are formed of the same kind of synthetic resin material.