JP2008068646A - Power unit structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit structure having a V-belt type automatic transmission between an internal combustion engine and a vehicle driving wheel and integrating these, which exhibits good maintenance properties for a clutch and prevents the influence of heat generation of the clutch on other parts. <P>SOLUTION: This structure is provided with an inner side case half body covering the V-belt type transmission consisting of a driving pulley and a driven pulley from the side of the internal combustion engine, and an outer side case half body covering the transmission from the outside. The supporting shaft of the driven pulley is passed through the outer side case half body and extended to the outside, and a centrifugal clutch is provided in the extended section. Moreover, a cover covering the clutch is provided, and the clutch is a wet type. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a V-belt automatic transmission between an internal combustion engine and a vehicle driving wheel, a wet centrifugal clutch at an end of a driven shaft of the V-belt automatic transmission, and a power unit in which these are integrated. Concerning structure.

  Conventionally, a dry type is often used as a centrifugal clutch provided at the end of a driven shaft of a V-belt type automatic transmission. As the above-mentioned centrifugal clutch, it is said that the wet type is more durable than the dry type which easily causes wear. Therefore, some attempts have been made regarding the use of the wet centrifugal clutch (see, for example, Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2003-301903 (FIG. 3).

  The structure disclosed in Patent Document 1 has a structure in which a wet centrifugal clutch is accommodated in a crankcase, and therefore the maintenance performance of the clutch is not good. Further, in the above structure, since the clutch chamber is adjacent to the V-belt type transmission chamber, heat generation of the clutch has an effect, which is not preferable. An object of the present invention is to provide a power unit structure that has good maintainability of the clutch and that is not affected by the heat generated by the clutch.

  The present invention solves the above problems, and the invention according to claim 1 is a power unit structure in which a V-belt type automatic transmission is provided between an internal combustion engine and a vehicle driving wheel, and these are integrated. An inner case half that covers the V-belt transmission consisting of a driving pulley and a driven pulley from the internal combustion engine side, and an outer case half that covers the V-belt transmission from the outside. The present invention relates to a power unit structure, characterized in that a centrifugal clutch is provided in the extended portion through a case half and extended outward, and a cover for covering the clutch is provided.

  According to a second aspect of the present invention, in the power unit structure according to the first aspect, the clutch is wet, and includes a cylindrical boss extending from the clutch drive plate supporting the clutch shoe to the pulley side. An oil seal material is interposed between the outer case half and the outer case half.

  According to a third aspect of the present invention, in the power unit structure according to the second aspect, the cylindrical boss includes a spring seat portion.

  According to the first aspect of the present invention, the clutch exclusive chamber can be provided while simplifying the power transmission structure to the rear wheel portion by a simple structure in which a small cover is added outside the outer case half. Maintainability is improved.

In invention of Claim 2, durability of a clutch improves by making a clutch wet,
By interposing an oil seal between the cylindrical boss and the outer cover, it becomes possible to form a clutch chamber filled with oil for wet clutches, and the clutch chamber is formed outside the V-belt type transmission chamber. Therefore, the cooling performance of the clutch chamber is improved, the influence of the clutch operation heat generation on the V-belt type transmission chamber can be reduced, and the life of the belt can be improved.

  According to the invention of claim 3, the number of parts can be reduced.

  FIG. 1 is a longitudinal sectional view of a power unit P according to an embodiment of the present invention, and FIG. 2 is a horizontal sectional view including a crankshaft 15 and a driven shaft 50 of the power unit P. This power unit P is mounted on a motorcycle, and is an internal combustion engine E on the front side of the vehicle body and a V-belt type continuously variable transmission T that is a power transmission device that is biased to the left and extends rearward from the internal combustion engine E, and V It comprises a reduction gear mechanism G provided at the rear of the belt type continuously variable transmission T. The internal combustion engine E is a one-cylinder four-stroke internal combustion engine.

  The main part of the unit case of the power unit P includes a right unit case 3, a middle unit case 4 and a left unit case 5. The reciprocating motion of the piston 16 slidably fitted to the cylinder bore 12a of the cylinder block 12 is transmitted to the crankshaft 15 rotatably supported by the unit cases 3 and 4 via the connecting rod 17, and the crankshaft 15 Rotates. An ignition plug 26 is attached to the combustion chamber 25 formed on the lower surface of the cylinder head 13 facing the top surface of the piston 16 with the electrodes exposed.

  The cylinder block 12 tilts forward to near horizontal and protrudes forward from the unit cases 3 and 4. The cylinder head 13 is superimposed on the cylinder block 12, and the valve mechanism 20 provided on the cylinder head 13 is connected to the cylinder head cover 14. Covering. An intake rocker arm 22i and an exhaust rocker arm 22e are slidably in contact with the camshaft 21 of the valve mechanism 20, and an intake valve and an exhaust valve (not shown) are opened and closed by these rocker arms. The camshaft has a reduction ratio of 1/2 that of the crankshaft 15 by a timing chain 24 spanned between a driven sprocket 23b fitted to the right end of the camshaft 21 and a drive sprocket 23a fitted to the crankshaft 15. 21 rotates.

  The crankshaft 15 is rotatably supported by the right unit case 3 and the middle unit case 4 via a right bearing 10 and a left bearing 11, and is disposed at the right end of the crankshaft 15 protruding rightward from the right bearing 10. The rotor 27r of the alternator 27 is fitted, and the right side thereof is covered with the generator cover 8 coupled to the right unit case 3, and the stator 27s of the alternator 27 is attached to the generator cover 8.

  The middle unit case 4 extends rearward and is elongated in the front-rear direction and is opened toward the left. The left open part of the middle unit case 4 (corresponding to the inner case half according to claim 1) is connected to the left unit case 5 (corresponding to the outer case half according to claim 1) from the left. A power transmission chamber D that covers and accommodates the V-belt continuously variable transmission T is formed. That is, the middle unit case 4 and the left unit case 5 constitute a transmission case.

  A drive pulley 30 of a V-belt continuously variable transmission T is attached to the left end portion of the crankshaft 15 protruding leftward from the left bearing 11 provided in the middle unit case 4. The drive pulley 30 is fixed to the crankshaft 15 as a drive shaft in the axial direction and the rotation direction, and has a drive side fixed pulley half 30a having a conical surface with which the V belt 31 contacts, and a drive side fixed pulley half 30a. A drive-side movable pulley half 30b having a conical surface that is coupled to the crankshaft 15 so as to be axially movable with respect to the crankshaft 15 and non-movable in the rotational direction, and to contact with the V-belt 31; On the other hand, a lamp plate 30c fixed in the axial direction and the rotation direction, and a plurality of weight rollers 30d arranged between the driving side movable pulley half 30b and the lamp plate 30c are provided.

  A clutch case 5a that accommodates a wet centrifugal clutch C, which will be described later, is formed at the rear part of the left unit case 5, the outer opening thereof is covered with a clutch cover 6, and a clutch chamber R is formed inside. The clutch cover 6 is attached to the clutch case 5a by a bolt 60 with an O-ring 59 interposed therebetween. The clutch cover 6 is provided with an oil injection port 65 and an oil discharge hole 66. The oil injection port 65 is closed by a cap 67, and the oil discharge hole 66 is closed by screwing a bolt-shaped lid 68.

  At the rear of the power transmission chamber D, a driven shaft 50 with respect to the crankshaft 15 serving as a drive shaft is rotatably supported by the middle unit case 4, the clutch cover 6 and the gear case cover 7 via respective bearings 34, 35 and 36. It is supported. A rotating sleeve 37 is supported on the driven shaft 50 via bearings 38 and 39 so as to be relatively rotatable. A driven pulley 40 that is paired with the driving pulley 30 is provided on the rotating sleeve 37.

  FIG. 3 is an enlarged horizontal sectional view of the rear part of the power unit P. In FIG. 3, a central cylindrical member 49 integral with the clutch outer 48 of the centrifugal clutch C is fitted in a non-rotatable manner through a spline on a driven shaft 50 that passes through the rotary sleeve 37 and extends to the left from its left end. It is fixed by 51. The clutch outer 48 and the central cylindrical member 49 are connected by welding. Thereby, the clutch outer 48 is integrated with the driven shaft 50. Inside the hook-shaped clutch outer 48, a cylindrical boss 43, a pressing member 44, and a clutch drive plate 45 are integrally formed on the outer periphery of the fixed sleeve 42 provided on the outer periphery of the driven shaft 50 with respect to the fixed sleeve 42. And is supported so as to be relatively rotatable.

  The outer peripheral portion of the cylindrical boss 43 into which the clutch drive plate 45 is fitted has a so-called D-cut in which a part of the circular cross section is notched in a straight line, and the clutch drive plate 45 has a hole having the same shape as the above cross section. Is provided to prevent the rotation by fitting in the D-cut portion. In this state, the pressing member 44 is fixed to the cylindrical member 43 with the screw 32 with the clutch drive plate 45 interposed therebetween, and these are integrated. The cylindrical boss 43 is coupled to the rotary sleeve 37 with a screw 33. Therefore, the driven pulley 40, the rotating sleeve 37, the cylindrical boss 43, the clutch drive plate 45, and the pressing member 44 are integrally rotated around the driven shaft 50.

  In the above embodiment, the D-cut method is described as the rotation stop of the clutch drive plate 45, but the clutch drive plate 45 and the cylindrical boss 43 may be welded. In this case, the pressing member 44 is not necessary.

  The cylindrical boss 43 is a rotating member, and the clutch case 5a is a fixed member. Since oil needs to be injected into the clutch chamber R, an oil seal member 58 is interposed between the cylindrical boss 43 and the clutch case 5a, and the clutch chamber R is sealed. Similarly, an oil seal material 57 is interposed between the end of the pressing member 44 and the central cylindrical member 49 of the clutch outer 48 to prevent oil leakage.

  The driven pulley 40 is a driven-side fixed pulley half 40a that is integrally attached to the rotating sleeve 37 and prohibited from moving in the axial direction, and a driven that can move in the axial direction on the outer periphery of the rotating sleeve 37 and can move slightly in the rotating direction. A side movable pulley half 40b and a cylindrical compression coil spring 40c that urges the driven side movable pulley half 40b toward the driven side fixed pulley half 40a are provided. One end of the compression coil spring 40 c is supported by a spring seat 41 provided on the cylindrical boss 43.

  When the driven pulley 40 rotates at a rotational speed greater than a predetermined rotational speed, the plurality of clutch shoes 46 supported by the clutch drive plate 45 in a swingable manner are diametrically caused by centrifugal force against the spring force of the clutch spring 47. The friction member 46a provided on the outer peripheral surface of each clutch shoe 46 abuts on the inner peripheral surface of the clutch outer 48, the centrifugal clutch C is connected, and the rotation of the driven pulley 40 is driven by the driven shaft. Transmitted to 50.

  The centrifugal clutch is wet, and engine oil of about 10% of the volume of the clutch chamber R is injected. FIG. 1 shows the oil level L in the clutch chamber R when the engine is stopped. As a result, the inner surface of the clutch outer is always lubricated with oil, so that the clutch shoe 46 smoothly contacts the clutch outer 48 and the transmission torque is stabilized. Further, the durability of the clutch is improved by oil lubrication. The clutch chamber R is a chamber that accommodates only the clutch, and maintenance of only the clutch can be easily performed by opening the small clutch cover 6.

  A V-belt 31 wound around the conical surfaces of the driving-side fixed pulley half 30a and the driving-side movable pulley half 30b of the front driving pulley 30 is behind the driven-side fixed pulley half of the driven pulley 40. 40a and the driven-side movable pulley half 40b are wound around the conical surfaces facing each other.

  Since the V-belt type continuously variable transmission T is configured in this way, when the rotational speed of the internal combustion engine E is low, the drive-side movable pulley half 30b is separated from the drive-side fixed pulley half 30a in the drive pulley 30. Thus, the winding radius of the V-belt 31 is reduced, and in the driven pulley 40, the driven-side movable pulley half 40b biased by the compression coil spring 40c approaches the driven-side fixed pulley half 40a, and V Since the winding radius of the belt 31 is increased, the power of the crankshaft 15 is transmitted to the output shaft with a large gear ratio.

  When the rotational speed increases, in the driving pulley 30, the plurality of weight rollers 30d move radially outward by centrifugal force so that the driving-side movable pulley half 30b approaches the driving-side fixed pulley half 30a. As a result, the winding radius of the V-belt 31 is increased, and in the driven pulley 40, the driven-side movable pulley half 40 moves away from the driven-side fixed pulley half 40 against the spring force of the spring 40, and the V-belt Since the winding radius of 31 is small, the gear ratio is small.

  A gear case cover 7 is placed on the right side of the rear part of the middle unit case 4 to form a reduction gear chamber 52, and the reduction gear mechanism G is accommodated in the reduction gear chamber 52. In the reduction gear chamber 52, a reduction gear shaft 53 is rotatably supported via bearings 54 and 54 in parallel with the driven shaft 50, and a rear axle 55 is rotatably supported via bearings 56 and 56. It is supported. The rear axle 55 passes through the gear case cover 7 and the right half protrudes to the outside. The rear wheel is supported on the right half.

  A small-diameter gear 50a is formed in a portion of the driven shaft 50 protruding into the reduction gear chamber 52, and the large-diameter gear 53a fitted to the reduction gear shaft 53 meshes with the small-diameter gear 50a so as to be integrated with the reduction gear shaft 53. The formed small diameter gear 53b meshes with a large diameter gear 55a fitted to the rear axle 55. Therefore, the rotation of the driven shaft 50 is decelerated via the reduction gear mechanism G and transmitted to the rear axle 55, and the rear wheels rotate.

  As described above, the power of the crankshaft 15 of the internal combustion engine E is input to the drive pulley 30 of the V-belt continuously variable transmission T, and the V-belt continuously variable transmission T responds to the rotational speed of the internal combustion engine E. The gear is automatically shifted at a gear ratio, transmitted to the driven pulley 40, and further transmitted to the driven shaft 50 via the centrifugal clutch C. Then, the rotation of the driven shaft 50 is transmitted to the rear axle 55 after being decelerated by the reduction gear mechanism G.

  An intake hole cover 9 (FIG. 2) is attached to the left side of the front part of the left unit case 5 to cover the air intake opening 61 of the left unit case 5. A fan 62 is formed on the left side surface of the driving-side fixed pulley half 30a fitted to the crankshaft 15. When the driving-side fixed pulley half 30a rotates together with the crankshaft 15, the fan 62 rotates to Air flowing in from the front of the hole cover 9 is sucked into the power transmission chamber D from the air suction opening 61, and the V-belt type continuously variable transmission T is cooled. The cooled air is discharged from an air discharge opening 63 (FIG. 1) provided at the rear part of the unit cases 4 and 5.

  On the other hand, oil is injected into the clutch chamber R, and the clutch C is cooled. That is, frictional heat generated between the clutch outer 48 and the friction member 46a of the clutch shoe 46 is transmitted to the peripheral wall portion of the clutch case 5a and the clutch cover 6 by oil. Since the outer surface of the peripheral wall portion is in contact with the outside air, it is cooled and heat is dissipated. Therefore, since the heat generated in the clutch C is independently cooled by the outside air and is not transmitted to the V-belt continuously variable transmission T, the cooling of the V-belt continuously variable transmission T and the clutch C is separately performed. Done effectively.

In the embodiment described above in detail, the following effects are brought about.
(1) The durability of the clutch is improved by making the clutch C wet and oil-lubricated.
(2) Since oil is interposed between the clutch shoe 46 and the clutch outer 48, torque transmission is smooth and stabilized.
(3) Since the clutch exclusive chamber R is provided outside the left unit case 5, the maintenance of the clutch alone is possible.
(4) Since the clutch chamber R is formed outside the V-belt type transmission chamber, the cooling performance of the clutch chamber is improved, the influence of the clutch operation heat generation on the V-belt type transmission chamber can be reduced, and the life of the belt To improve.
(5) An oil seal between the rotating cylindrical boss 43 and the fixed clutch case 5a (formed as a part of the left unit case 5 corresponding to the outer case half according to claim 2). By interposing 58, it is possible to form the clutch chamber R filled with wet clutch oil.
(6) Since the spring seat 41 is provided on the cylindrical boss 43, the number of parts can be reduced.

It is a longitudinal section of power unit P concerning one embodiment of the present invention. It is a horizontal sectional view including the crankshaft and the driven shaft of the power unit P. It is an expanded horizontal sectional view of the rear part of the power unit P.

Explanation of symbols

  P: Power unit, E: Internal combustion engine, T: V belt type continuously variable transmission, C: Wet centrifugal clutch, R: Clutch chamber, L: Oil level when the engine is stopped, 3 ... Right unit case, 4 ... Middle unit case 5 ... Left unit case, 5a ... Clutch case, 6 ... Clutch cover, 15 ... Crankshaft, 30 ... Drive pulley, 31 ... V belt, 40 ... Driven pulley, 41 ... Spring seat, 43 ... Cylindrical boss, 44 ... Presser 45, clutch drive plate, 46 ... clutch shoe, 46a ... friction member of clutch shoe, 47 ... clutch spring, 48 ... clutch outer, 49 ... central cylindrical member of clutch outer, 50 ... driven shaft, 58 ... oil seal material .

Claims (3)

In the power unit structure comprising a V-belt type automatic transmission between the internal combustion engine and the vehicle driving wheel, and integrating them,
An inner case half that covers the V-belt transmission including the driving pulley and the driven pulley from the internal combustion engine side; and an outer case half that covers the V-belt transmission from the outside.
A power unit structure characterized in that a support shaft of a driven pulley extends outwardly through an outer half of the case, a centrifugal clutch is provided at the extending portion, and a cover for covering the clutch is provided. The clutch is wet,
It has a cylindrical boss extending from the clutch drive plate that supports the clutch shoe to the pulley side,
The power unit structure according to claim 1, wherein an oil seal material is interposed between the cylindrical boss and the outer case half.   The power unit structure according to claim 2, wherein the cylindrical boss includes a spring seat portion.

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