V-belt type continuously variable transmission

The present invention relates to a V-belt type continuously variable transmission, and more particularly to a V-belt type continuously variable transmission which is attached to the crankshaft of an engine via a centrifugal clutch.

The V-belt type continuously variable transmission has a type having a clutch function capable of disconnecting the power transmission between the V-belt and the drive pulley assembly (Patent Document 1), and there is always a gap between the V-belt and the drive pulley assembly. There is a type (Patent Document 2) in which a centrifugal clutch or the like is separately arranged between the drive shaft and the crankshaft of the engine, which are connected so as to be able to transmit power.

In the former case, since it is not necessary to separately provide a centrifugal clutch or the like, the entire configuration of the power transmission system can be simplified and the entire power transmission system can be made compact. However, at the time of clutch disengagement, for example, a return spring is required to urge the movable sheave of the drive pulley assembly to the clutch disengagement position, and the V-belt continuously variable transmission becomes large and complicated, and V The clutch capacity is also limited by the frictional force between the belt and the movable sheave.

FIG. 6 shows an example of the latter. Since the centrifugal clutch 307 is arranged between the drive shaft 302 of the V-belt continuously variable transmission 301 and the crankshaft 304 of the engine 303, the power transmission system as a whole However, since the return spring described above is not required, the structure of the V-belt continuously variable transmission 301 itself can be simplified and a large clutch capacity can be secured. In FIG. 6, hatching is not performed to show a cross section.

Briefly explaining the conventional structure of FIG. 6, the centrifugal clutch 307 is housed in the clutch cover 311 attached to the engine 303 crankcase 310, and the clutch input shaft 312 is integrally formed with the crankshaft 304 to form a clutch. The clutch housing 314 on the output side is rotatably supported on the inner surface of the clutch cover 311 via a ball bearing 315.

The transmission case assembly 320 is composed of a transmission case body 321 integrally molded with the crankcase 310 and a transmission cover 322 attached to the transmission case body 321 with bolts. The 322 is made of resin for weight reduction. The driven shaft 330 of the V-belt type continuously variable transmission 301 is integrally molded with the input shaft 332 of the gear type continuously variable transmission 331, and is cantilevered and supported by the crankcase 310. One end of the drive shaft 302 is integrally connected to the clutch housing 314 on the output side of the centrifugal clutch 307, and the other end of the drive shaft 302 is made of aluminum formed of a member separate from the transmission cover 322. It is rotatably supported by the boss portion 333 of the above via a bearing 334 or the like. A stay portion 333a extending along the inner surface of the transmission cover 322 is integrally formed on the aluminum boss portion 333, and the stay portion 333a is formed on the cover mounting surface of the transmission case main body 321 together with the transmission cover 322. It is fixed. By supporting the other end of the drive shaft 302 with the aluminum boss portion 333 and the stay portion 333a, the rigidity of the drive shaft 302 against bending stress is increased.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2003-184972</text></patcit><patcit num="2"><text>JP-A-2007-71255</text></patcit>

<p> However, if the aluminum boss portion 333, which is a separate member from the transmission cover 322, is provided to support the other end of the drive shaft 302 as in the conventional structure shown in FIG. 6, the number of parts is increased. As the number increases, the assembly work of the transmission case assembly 320 becomes complicated.</p><p> The present invention has been made in view of the above problems, and in a V-belt type continuously variable transmission attached to a crankshaft via a centrifugal clutch, the drive shaft has high support rigidity without increasing the number of parts. The purpose is to be able to support both sides.</p>

<p> In order to solve the above problems, the V-belt type continuously variable transmission according to the present invention is a V-belt type continuously variable transmission attached to the crankshaft of the engine via a centrifugal clutch, and is provided on the drive shaft. A drive pulley assembly, a driven pulley assembly provided on a driven shaft, a V-belt wound between the two pulley assemblies, and a transmission case assembly for accommodating the both pulley assemblies and the V-belt. , One end of the drive shaft in the axial direction is connected to the output side rotating member of the centrifugal clutch, and the other end of the drive shaft is a boss portion formed in the transmission case assembly. It is rotatably supported.</p><p> According to the above configuration, for supporting the drive shaft of the V-belt type continuously variable transmission, the drive shaft can be supported by both sides without providing a shaft support member separate from the transmission case assembly. , The assembly work of the transmission case assembly becomes easy, and the number of parts of the V-belt type continuously variable transmission can be reduced.</p><p> In addition to the above features, the present invention can have the following features. (1) The transmission case assembly includes a transmission case body fixed or integrally formed on the crankcase of the engine, and an aluminum or aluminum alloy transmission cover attached to the transmission case body. The boss portion is formed on the transmission cover.</p><p> According to the above configuration, since the other end of the drive shaft is supported by the boss portion formed on the transmission cover made of aluminum or aluminum alloy, the support rigidity of the drive shaft can be improved and the strength of the transmission cover can be improved. Also improves. In addition, heat dissipation is also improved.</p><p>(2) The one end portion of the drive shaft is supported by a shaft support portion formed on the transmission case main body together with the output side rotating member of the centrifugal clutch.</p><p> According to the above configuration, the support structure at one end of the drive shaft can also be simplified.</p><p>(3) Reinforcing ribs are formed on the transmission cover. The rib for reinforcement can be formed so as to extend radially from the center of the boss portion.</p><p> According to the above configuration, the rigidity of the transmission cover can be increased and the support strength of the other end of the drive shaft can be increased without increasing the wall thickness of the transmission cover. In particular, when ribs are formed radially from the boss portion, the rigidity of the boss portion and its vicinity can be intensively improved. In addition, the reinforcing ribs can reduce the vibration of the transmission cover and reduce the generation of noise.</p><p>(4) A seal is arranged on the mating surface between the transmission cover and the transmission case main body.</p><p> According to the above configuration, it is possible to prevent not only the dustproof effect but also the vibration of the engine or the like from being transmitted to the transmission cover and the generation of noise.</p>

[First Embodiment of the present invention] 1 to 4 show an engine and a four-wheeled vehicle provided with a V-belt type continuously variable transmission according to the first embodiment of the present invention, and one embodiment of the present invention is based on these drawings. Will be explained.

FIG. 1 is a left side view of the four-wheeled vehicle. The small four-wheeled vehicle for rough terrain (so-called utility vehicle) is provided with a pair of left and right front wheels 2 on the front portion of the vehicle body frame 1, and the vehicle body frame. A pair of left and right rear wheels 3 are provided at the rear of 1, a cabin 6 surrounded by a cabin frame 5 is provided between the front wheels 2 and the rear wheels 3, a loading platform 7 is provided behind the cabin 6, and the front wheels 2 are provided. A fender (not shown) is provided above the rear wheel 3 and above the rear wheel 3, and a bonnet 8 and a bumper 9 are provided in front of the cabin 6.

A bench-shaped front seat 10 is installed in the front half of the cabin 6, a foldable bench-shaped rear seat 11 is installed in the second half of the cabin 6, and a dashboard (operation) is installed at the front end of the cabin 6. Part) 12 is provided.

The engine room 14 is formed so as to extend from the lower space of the front seat 10 to the lower space of the rear seat 11, and is located at the center of the vehicle in the vehicle width direction. 20 is stored and supported by the body frame 1. The engine 20 is a single cylinder engine and has a single cylinder 21 tilted forward. In particular, in order to reduce the overall height of the engine 20, the inclination angle of the cylinder 21 is set to, for example, an inclination angle of approximately 60 ° or more with respect to the vertical direction. The engine 20 may also include an engine having a V-type or other type of cylinder.

The exhaust pipe 25 connected to the exhaust port (not shown) of the engine 20 extends rearwardly and is connected to the exhaust muffler 26 arranged under the loading platform 7.

In FIG. 4, a transmission case main body 40 having a clutch cover 40a integrally is connected to the left wall of the crankcase 30 of the engine 20 by a plurality of bolts 44, and the clutch cover 40a and the left wall of the crankcase 30 are connected. As a result, a clutch chamber 41 for accommodating the centrifugal clutch 39 is formed. The transmission case body 40 is made of aluminum or an aluminum alloy.

The transmission cover 42 is connected to the cover mounting surface at the left end of the transmission case body 40 by a plurality of bolts 45 via a trim seal 51 made of an elastic material, and is not connected to the continuously variable transmission case body 40. The speed transmission cover 42 constitutes the transmission case assembly 38. The inside of the transmission case assembly 38 is a continuously variable transmission room 43. The transmission cover 42 is made of aluminum or an aluminum alloy, similarly to the transmission case main body 40. Further, the transmission case main body 40 and the transmission cover 42 are positioned with each other by the knock pin 52. As described above, when the transmission case main body 40 and the transmission cover 42 are made of aluminum or an aluminum alloy, high strength can be obtained and the structure has excellent heat dissipation.

The left journal portion 35b of the crankshaft 35 of the engine 20 is rotatably supported in a bearing hole on the left wall of the crankcase 30 via a ball bearing 36. The left journal portion 35b is integrally formed with a clutch shaft 55 on the clutch input side that protrudes into the clutch chamber 41. A boss portion 56a of the inner member 56 of the centrifugal clutch 39 is spline-fitted on the outer peripheral surface of the clutch shaft 55 so as to rotate integrally with the clutch shaft 55. The boss portion 60a of the clutch housing 60 is fitted to the outer peripheral surface of the boss portion 56a via a one-way clutch. The boss portion 60a of the clutch housing 60 is integrally formed with the drive shaft 59 of the V-belt type continuously variable transmission 46, and is rotatably supported on the inner peripheral surface of the clutch cover 40a via a ball bearing 61. ..

A transmission chamber 31 is provided at the rear of the crankcase 30, and a gear-type transmission having a shift input shaft 32, a shift output shaft 33, and the like (gears and the like are omitted) is arranged in the transmission chamber 31. .. The speed change output shaft 33 is connected to the rear wheel 3 (FIG. 1) so as to be able to transmit power via a bevel gear mechanism, a power transmission shaft, and the like. The shift input shaft 32 is rotatably supported on the left wall of the transmission chamber 31, and a driven shaft 63 of the V-belt type continuously variable transmission 46 is formed integrally with the shift input shaft 32.

(V-belt continuously variable transmission 46) The V-belt type continuously variable transmission 46 arranged in the continuously variable transmission room 43 is located in the drive pulley assembly 65 arranged in the front part of the continuously variable transmission room 43 and in the rear part of the continuously variable transmission room 43. The transmission case assembly that houses the arranged driven pulley assembly 66, the V-belt 67 wound around both pulley assemblies 65,66, and both pulley assemblies 65,66 and V-belt 67. It is composed of 38 and.

(Structure of drive pulley assembly 65) The drive pulley assembly 65 includes a fixed sheave 69 fixed to the drive shaft 59 so as not to be movable in the drive shaft direction, a movable sheave 70 fitted to the drive shaft 59 so as to be movable in the drive shaft direction, and a fly weight type. It is composed of a sheave thrust generation mechanism 71 and the like. As described above, one end portion, that is, the right end portion in the axial direction of the drive shaft 59 is integrally formed with the boss portion 60a of the housing 60 on the clutch output side of the centrifugal clutch 39, and the clutch cover 40a is formed via the ball bearing 61. It is supported by the inner peripheral surface of the. The other end of the drive shaft 59, that is, the left end, is rotatably supported on the inner peripheral surface of the boss portion 93 formed on the transmission cover 42 via a ball bearing 94. That is, the drive shaft 59 is supported by both the inner peripheral surface of the clutch cover 40a and the boss portion 93 of the transmission cover 42. The center of the boss portion 93 of the transmission cover 42 is aligned with the center of the bearing hole portion (the portion supporting the ball bearing 61) of the transmission case 40 by the knock pin 52.

The fixed sheave 69 is screwed to the right end of the drive shaft 59. The movable sheave 70 faces the fixed sheave 69 from the left in the drive shaft direction, and is fitted to the drive shaft 59 so as to be movable in the drive shaft direction. The V-belt 67 is sandwiched and held from the left and right by the conical pressing surfaces formed on both sheaves 69 and 70.

A square frame-shaped receiving plate 73 is connected to the back surface of the movable sheave 70 via a plurality of connecting arms 72 extending to the left, and the receiving plate 73 moves integrally with the movable sheave 70 in the drive axial direction.

The sheave thrust generation mechanism 71 is arranged between the back surface of the movable sheave 70 and the receiving plate 73, and includes a plurality of (for example, four) fly weights 75, a roller support member 76, a plurality of pressure receiving rollers 77, and a plurality of pressure receiving rollers 77. It is composed of. The roller support member 76 is screwed to the left end of the drive shaft 59 and rotates integrally with the drive shaft 59, and is movable by engaging the roller support member 76 with the connecting arm 72 in the circumferential direction. The sheave 70 rotates integrally with the drive shaft 59 via the roller support member 76. The plurality of fly weights 75 are arranged at intervals in the circumferential direction of the drive shaft 59. Each fly weight 75 is rotatably supported on the back surface of the movable sheave 69 via a support shaft 78, and is in contact with each of the pressure receiving rollers 77 from the right side.

(Structure of driven pulley assembly 66) The driven pulley assembly 66 is composed of a fixed sheave 81 that is immovably fixed to the driven shaft 63 in the driven axial direction, a movable sheave 82 that is movably fitted to the driven shaft 63 in the driven axial direction, and the like. It is configured. As described above, the driven shaft 63 is integrally formed with the shift input shaft 32 of the gear type transmission, and is cantilevered by the boss portion 95 on the left wall of the crankcase 30 via a ball bearing 96. There is.

A cam cylinder 83 having a plurality of spiral cam grooves 83a is fixed to the outer peripheral surface of the driven shaft 63, and the inner peripheral end of the fixed sheave 81 is screwed to the left end portion of the cam cylinder 83. That is, the fixed sheave 81 and the cam cylinder 83 rotate integrally with the driven shaft 63. The movable sheave 82 is arranged to face the fixed sheave 81 from the right side in the driven axial direction, and a sleeve 85 for supporting a roller is integrally connected to the inner peripheral end of the movable sheave 82. The sleeve 85 is fitted to the outer peripheral surface of the cam cylinder 83 so as to be movable in the driven axial direction, and is urged to the fixed sheave 81 side (left side) by the pressure adjusting spring 87, and is driven by the pressure adjusting spring 87. The belt winding radius of the plate assembly 66 is maintained at the maximum diameter (low position).

A roller 86 movably engaged with the spiral cam groove 83a is supported on the sleeve 85, and when the tension of the V-belt 67 increases as the load on the wheel side increases while the vehicle is running, the movable sheave 82 Rotates in the direction of rotation relative to the fixed sheave 81, and due to the cam action between the cam groove 83a of the cam cylinder 83 and the roller 86, the sleeve 85 and the movable sheave 82 are on the right with respect to the cam cylinder 83. It spirals toward and reduces the winding radius of the belt of the driven pulley assembly 66. (Cooling device for V-belt continuously variable transmission 46)

In FIG. 3, an air intake 88 is opened on the upper wall of the transmission case main body 40 at a position substantially directly above the drive shaft 59, and as shown in FIG. 2, air is provided at the air intake 88. The intake duct 89 is connected. The air intake duct 89 is formed in a substantially L shape in a side view and extends forward, and communicates with, for example, in the bonnet 8 of FIG.

In FIG. 2, an air discharge port 90 is opened at the rear end of the transmission cover 42 at a position near the rear of the driven shaft 63, and an air discharge duct 91 is connected to the air discharge port 90. There is.

In FIG. 4, a plurality of first cooling fins 101 are formed on the back surface (right side surface) of the fixed sheave 69 at equal intervals in the circumferential direction. The first casing 102 for the first cooling fan is arranged at a position separated by a predetermined gap to the right in the drive shaft direction with respect to the right end edge of the first cooling fin 101. The first casing 102 is fixed to the portion of the clutch cover 40a of the transmission case body 40 by a bolt 103, and an air inlet 105 is provided at the center of the first casing 102 so as to surround the clutch cover 40a. I have.

In FIGS. 3 and 4, the driven pulley assembly 66 is also formed with a plurality of second cooling fins 111 at equal intervals in the circumferential direction. In the front half of the fixed sheave 81, a second casing 112 having a substantially semicircular arc shape is arranged at a position separated by a predetermined gap to the left in the drive axis direction with respect to the left end edge of the second cooling fin 111. ing.

In FIG. 4, a part 42a of the continuously variable transmission cover 42 faces the left end edge of the second cooling fin 111 from the left at a predetermined interval in the latter half of the fixed sheave 81 of the driven pulley assembly 66. As a result, a part 42a of the continuously variable transmission cover 42 serves as a second casing.

An air guide portion 120 projecting to the left is integrally formed at a position corresponding to the front-rear direction of both pulley assemblies 65 and 66 of the transmission case body 40, and the air guide portion 120 is a drive pulley. The air sent from the first cooling fan (fixed sheave 69) of the assembly 65 is guided to the air inlet 115 at the center of the driven pulley assembly 66 on the rear left side.

(Action) In FIG. 4, when the engine is stopped or idle rotation, the centrifugal clutch 39 is disengaged, so that the drive shaft 59 of the V-belt type continuously variable transmission 46 is not rotating. At this time, the movable sheave 70 of the drive pulley assembly 65 is integrally moved to the maximum open position with the receiving plate 73. On the other hand, the movable sheave 82 of the driven pulley assembly 66 is moved to the most fixed sheave 81 side (leftmost position side) by the pressure adjusting spring 87. That is, the reduction ratio of the V-belt continuously variable transmission 46 is in the low state (maximum deceleration state).

When the engine speed is increased from idling rotation, the centrifugal clutch 39 is connected and the drive shaft 59 starts to rotate. First, in the low state, from the drive pulley assembly 65 to the driven pulley assembly 66 via the V-belt 67. Power is transmitted.

When the engine speed further increases, the fly weight 75 of the sheave thrust generation mechanism 71 rotates in the arrow S direction due to centrifugal force, and pushes the pressure receiving roller 77. Since the pressure receiving roller 77 itself does not move in the drive shaft direction, the movable sheave 70 and the receiving plate 73 integrally move to the right in the drive shaft direction due to the reaction force of the pressure receiving roller 77, and are fixed to the movable sheave 70. Reduce the distance from the sheave 69. As a result, the V-belt 67 moves outward in the radial direction, and the winding radius increases.

When the winding radius of the V-belt 67 of the drive pulley assembly 65 increases, in the driven pulley assembly 66, the tension of the V-belt 67 increases, so that the left and right sides of the V-belt 67 and both sheaves 81 and 82 are pressure-welded. Power increases. As a result, the movable sheave 82 is spirally moved to the right with respect to the fixed sheave 81 against the pressure adjusting spring 87, widening the distance between the movable sheave 82 and the fixed sheave 81, and the winding radius is increased. Decrease.

As described above, the reduction ratio becomes smaller due to the increase in the winding radius of the drive pulley assembly 65 and the decrease in the winding radius of the driven pulley assembly 66. That is, it shifts from the low state to the high state.

According to the embodiment, since the other end (left end) of the drive shaft 59 is supported by the boss portion 93 formed on the transmission cover 42, the transmission cover 42 is used to support the drive shaft 59. It is not necessary to provide a shaft support member separate from the shaft support member, the number of parts of the V-belt type continuously variable transmission 46 can be reduced, the structure can be simplified, and the assembly work becomes easy. Moreover, since the transmission cover 42 is made of aluminum or an aluminum alloy like the transmission case main body 40, the support rigidity of the drive shaft 59 is further improved, and excellent heat dissipation can be obtained.

Further, since one end of the drive shaft 59 is supported by the clutch cover 40a together with the housing 60 on the clutch output side of the centrifugal clutch 39, the number of parts can be reduced by this as well.

Further, since the trim seal 51 made of elastic material is arranged on the mating surface between the transmission case main body 40 and the transmission cover 42, vibration of the engine or the like is prevented from being transmitted to the transmission cover 42, and noise is prevented. Can be prevented.

[Other embodiments] (1) FIG. 5 is a second embodiment, and is a left side view of the transmission cover 42. The transmission cover 42 is made of aluminum or an aluminum alloy as in the first embodiment, and is integrally provided with a boss portion 93 for supporting the drive shaft. A plurality of, for example, three reinforcing ribs 53a, 53b, and 53c are formed on the left side surface (outer surface).

These reinforcing ribs 53a, 53b, and 53c are arranged at the rear half of the transmission cover 42 at intervals in the front-rear direction, and the reinforcing ribs 53a, 53b, and 53c extend substantially in the vertical direction to shift gears. It reaches from the upper end to the lower end of the machine cover 42. The front reinforcing rib 53a is formed substantially linearly when viewed from the side, the intermediate reinforcing rib 53b is slightly bent when viewed from the side, and the rear reinforcing rib 53c is lateral. Seen from the side, it is bent in an L shape.

By forming the reinforcing ribs 53a, 53b, and 53c on the transmission cover 42 in this way, the rigidity can be increased without increasing the wall thickness of the transmission cover 42, and there is no engine vibration or V-belt type. The vibration of the speed transmission can also be suppressed.

Further, in the embodiment shown in FIG. 5, a plurality of reinforcing ribs 201,202,203,204 extending radially from the center point of the boss portion 93 are provided on the left side surface (outer surface surface) and the right side surface (inner surface surface) of the front portion of the transmission cover 42. It is formed. By forming radial reinforcing ribs 201, 202, 203, 204 around the boss portion 93 in this way, the strength of the transmission cover 42 is not only improved, but also the other end of the drive shaft 59 is supported. The support rigidity of the boss portion 93 can be intensively improved.

(2) In the above embodiment, the transmission case main body 40 is formed separately from the crankcase 30 and fixed to the crankcase 30 by bolts 44, but the transmission case main body 40 is referred to as the crankcase 30. It can also be molded integrally. In this case, the crankcase 30 preferably has a left-right split structure.

(3) The present invention is not limited to the engine mounted on the four-wheeled vehicle for rough terrain as shown in FIG. 1, but is mounted on various vehicles such as motorcycles and tricycles, small watercraft, and the like. Of course, it can be applied to engines for vehicles, and it can also be applied to engines for vehicles. Furthermore, it can be applied to a multi-cylinder engine.

(4) The present invention is not limited to the structure of the above-described embodiment, and includes various modifications that can be considered without departing from the contents described in the claims.

<figref num="1">It is a left side view which shows the four-wheeled vehicle equipped with the engine equipped with the V-belt type continuously variable transmission according to one Embodiment of this invention by partially breaking.</figref><figref num="2">It is a left side view of the V-belt type continuously variable transmission of FIG. 1, and is the figure which shows the state which attached the transmission cover, the air introduction duct and the exhaust air duct.</figref><figref num="3">FIG. 1 is a left side view of the V-belt type continuously variable transmission shown in FIG. 1 with the transmission cover removed.</figref><figref num="4">FIG. 3 is a sectional view taken along line IV-IV of FIG.</figref><figref num="5">It is a side view of the transmission cover which concerns on 2nd Embodiment of this invention.</figref><figref num="6">It is a vertical cross-sectional view of a conventional example.</figref>

Code description

20 engine 30 crankcase 35 crankshaft 38 transmission case assembly 39 Centrifugal clutch 40 Transmission case body 42 transmission cover 51 Trim seal 53a, 53b, 53c Reinforcing ribs 59 drive shaft 60 Output side housing (example of output side rotating member) 61 Ball bearing (shaft support part) 63 driven axis 65 drive pulley assembly 66 Driven pulley assembly 67 V belt 93 Boss part 201,202,203,204 Reinforcing ribs in a radial arrangement