WO2003085242A1

WO2003085242A1 - Engine

Info

Publication number: WO2003085242A1
Application number: PCT/JP2003/004468
Authority: WO
Inventors: Akifumi Oishi; Yousuke Ishida
Original assignee: Yamaha Hatsudoki Kabushiki Kaisha
Priority date: 2002-04-08
Filing date: 2003-04-08
Publication date: 2003-10-16
Also published as: CN1615397A; JP4181051B2; CN1320263C; AU2003236000A1; JPWO2003085242A1

Abstract

An engine capable of transmitting a rotational force between a crankshaft and first and second driven shafts through first and second drive gears on the crankshaft side and first and second driven gears on the first and second driven shaft sides, wherein the first drive gear is fixedly installed on the crankshaft, the second drive gear is detachably engaged with the first drive gear so as to be overlapped with the engaged part of the first drive gear, the transmission of the rotational force between the crankshaft and the first driven shaft is performed directly between the first drive gear and the first driven gear, and the transmission of the rotational force between the crankshaft and the second driven shaft is performed through the second drive gear between the first drive gear and the second driven gear.

Description

Technical description Technical field

According to the present invention, a first driven shaft and a second driven shaft mounted on a crankshaft respectively drive a first driven shaft and a second driven shaft, for example, a lubricating oil pump shaft and a balancer shaft, or a kick shaft, for example. Accordingly, the present invention relates to an engine in which a crankshaft is rotationally driven via the first drive gear. Background art

For example, in a motorcycle engine, for example, a lubricating oil pump and a balancer shaft are generally driven to rotate by each of a plurality of drive gears mounted on a crankshaft (for example, see Japanese Patent Application Laid-Open No. H8-1899323). No.). In this case, each drive gear is set to an outer diameter corresponding to the purpose of the driven component. For example, the lubricating oil pump is driven at a rotation speed reduced from the engine rotation, and the balancer shaft is driven at the same rotation speed as the engine rotation, so the lubricating oil pump driving gear has a small diameter and the balancer shaft driving gear has a large Generally, the diameter is set. In addition, the crankshaft is equipped with a plurality of drive gears and crankshaft components such as a generator and a cam sprocket, and these gears and crankshaft components are compact as much as possible, and power transmission is reliable and maintenance is possible. It must be mounted to make it easier.

However, if the above-mentioned plurality of drive gears are simply arranged in parallel to the crankshaft, the axial thickness of each drive gear must be increased in order to firmly attach the drive gear to the crankshaft. I have a problem. In addition, when the drive gear is mounted by press fitting, there is a concern that maintenance such as replacement of the drive gear becomes difficult. The present invention has been made in view of the above-described conventional circumstances, and has as its object to provide an engine that can avoid an increase in the length of a crankshaft and that can easily perform maintenance such as replacement of a drive gear. Disclosure of the invention

The invention according to claim 1 is characterized in that, between the crankshaft and the second driven shaft, the first drive gear on the crankshaft side, the second drive gear and the first driven gear on the first and second driven shafts, In the engine configured to transmit torque via a second driven gear, the first driving gear is fixedly mounted on the crankshaft, and the second driving gear is connected to the first driving gear. The first drive gear is removably engaged so as to overlap the engaged portion of the first drive gear, and the transmission of the rotational force between the crankshaft and the first driven shaft is performed by the second drive gear and the second drive gear. (1) Directly between the driven gear and the transmission of the rotational force between the crankshaft and the second driven shaft, the transmission of the first driving gear and the second driven gear through the second driving gear. It is characterized by performing between.

In the present invention, transmitting the torque between the crankshaft and the first and second driven shafts means transmitting the torque of the crankshaft to the first and second driven shafts and transmitting the torque from the first and second driven shafts. This is intended to include a case where the rotating power from the shaft is transmitted to the crankshaft. In the former case, for example, the rotary shaft and balancer shaft of the lubricating oil pump, and in the latter case, for example, the kick shaft.

According to a second aspect of the present invention, in the first aspect, the first drive gear has a cylindrical shape having outer peripheral teeth (external gears) formed on an outer peripheral surface thereof, and is fixed to the crankshaft by press-fitting. The second drive gear is an annular gear having inner teeth (internal gears) and outer teeth (external gears) formed on an inner peripheral surface and an outer peripheral surface. It is characterized in that it is detachably fitted to the engaged portion of the outer peripheral teeth.

According to a third aspect of the present invention, in the first aspect, the first drive gear has a cylindrical shape having an outer peripheral tooth (external gear) on an outer peripheral surface thereof and an outer splan that follows the outer tooth. The second drive gear is annular and has an inner spline and outer teeth (external gear) on an inner peripheral surface and an outer peripheral surface. The gear is detachably fitted to the outer spline.

According to a fourth aspect of the present invention, in any one of the first to third aspects, an outer diameter of the first drive gear is set to be smaller than an inner diameter of a crankcase-side support hole of an adjacent crank journal bearing. (2) The crankcase side support hole can be fitted to the crank journal bearing with the drive gear removed.

A fifth aspect of the present invention is the invention according to any one of the first to fourth aspects, wherein a crankshaft component is detachably mounted outside the second drive gear and the crankshaft component is removed. The second drive gear can be detached from the crankshaft in a state where the crankshaft is in the closed state.

The invention of claim 6 is the invention according to any one of claims 1 to 5, wherein the first drive gear is combined with the kick gear train that transmits the rotation of the kick shaft to the crankshaft. Is characterized by a combination of a balancer gear train for transmitting the rotation of the crankshaft to the balancer shaft.

The invention of claim 7 is the invention according to claim 6, wherein the first drive gear comprises a pump gear train for transmitting the rotation of the crankshaft to the lubricating oil pump and the kick gear train for transmitting the rotation of the kick shaft to the crank shaft. The kick gear train and a part of the pump gear train are shared. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a left side view of a motorcycle equipped with an engine according to an embodiment of the present invention.

Fig. 2 is a cross-sectional plan view showing the deployed state of the engine (cross-sectional view taken along the line Π- Π in Fig. 6). It is.

FIG. 3 is a cross-sectional plan view of the continuously variable transmission mechanism and the centrifugal clutch mechanism of the engine.

FIG. 4 is a right side view of the engine.

FIG. 5 is a left side view of the engine.

Fig. 6 is a right side view of the engine with the continuously variable transmission mechanism and centrifugal clutch mechanism removed.

FIG. 7 is a right side view of the crankcase of the engine.

FIG. 8 is a cross-sectional rear view of the above crankcase (a cross-sectional view taken along the line VIII-VIII in FIG. 5).

FIG. 9 is a cross-sectional view (cross-sectional view taken along line IX-IX of FIG. 5) of the kick device of the engine. FIG. 10 is a cross-sectional view of the kick device.

FIG. 11 is a sectional view showing the lubricating oil path of the engine.

FIG. 12 is a cross-sectional view of the centrifugal clutch mechanism.

FIG. 13 is a side view of the centrifugal clutch mechanism.

FIG. 14 is an enlarged sectional view of a main part of the centrifugal clutch mechanism.

FIG. 15 is an enlarged sectional view of a main part of the centrifugal clutch mechanism.

FIG. 16 is a cross-sectional view of a conventional general driven pulley.

FIG. 17 is a view showing a modification of the engagement structure of the second drive gear in the above embodiment.

FIG. 18 is a diagram showing another modified example of the engagement structure of the first and second drive gears in the above embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIGS. 1 to 15 are diagrams for explaining a motorcycle engine according to an embodiment of the present invention. FIG. 1 is a left side view of a motorcycle equipped with the engine of the embodiment, and FIG. 2 is an engine. Fig. 3 is a sectional plan view of the continuously variable transmission mechanism and the centrifugal clutch mechanism of the engine, and Figs. 4 and 5 are right and left views of the engine. Fig. 6 is a right side view of the engine with the continuously variable transmission mechanism and centrifugal clutch mechanism removed, Fig. 7 is a right side view of the crankcase, and Fig. 8 is a cross-sectional plan view of the crankcase (Vin in Fig. 5). -VI II cross section), Fig. 9 is a cross section plan of the kick device of the engine (IX-IX cross section in Fig. 5), Fig. 10 is a cross section plan around the kick axis, and Fig. 11 is the engine lubrication. Sectional plan views showing the oil path, and Figs. 12 and 13 show the disconnection of the centrifugal clutch mechanism. Figures 14, 15 and 15 are enlarged cross-sectional views of the main parts of the centrifugal clutch mechanism. Note that the terms front and rear, left and right in the present embodiment mean front and rear and left and right as viewed from a seat.

In the drawing, reference numeral 1 denotes a motorcycle on which an engine 2 of the present embodiment is mounted. The motorcycle 1 includes a front fork 5 on which a front wheel 4 is supported by a head pipe 3 fixed to a front end of a body frame 1a. The rear arm 7 on which the rear wheel 7 is pivotally supported by the rear arm bracket 6 fixed at the center and rotatably pivoted, is pivotably supported up and down, and the driver is mounted on the upper part of the body frame 1a. It has a schematic structure in which a seat 9 composed of a passenger seat portion 9a and a rear passenger seat portion 9b is arranged.

The body frame 1a includes left and right down tubes 1b extending diagonally downward from the head pipe 3, and left and right upper tubes 1c extending diagonally upward following the rear end of each down tube 1b. It is composed of left and right seat rails 1d which are connected to the tube 1b and the upper tube 1c in such a manner as to extend forward and backward. The body frame 1a is surrounded by a resin body cover 10 made of a front cover 10a, a leg shield 1Ob, a side cover 10c, and the like.

A steering handle 11 is fixed to an upper end of the front fork 5, and the steering handle 11 is surrounded by a handle cover 1 la. In addition, The engine 2 is an air-cooled 4-cycle single-cylinder engine, and the cylinder axis A is provided at the rear lower part of the downtube 1b between the engine 8 and the rear arm bracket 6. It is suspended about 45 degrees forward. The engine 2 includes an engine body 15, a V-belt type continuously variable transmission mechanism 16, a wet multi-plate centrifugal clutch mechanism 17 and a reduction gear mechanism 18.

The engine body 15 has a cylinder head 20 connected to the upper surface of the cylinder block 19 and a head cover 21 provided above the cylinder head 20. It has a schematic structure in which a crankcase 22 in which a crankshaft 28 is housed is connected to the lower mating surface of 9.

An intake port 20b communicating with the combustion recess 20a is opened on the rear surface of the cylinder head 20. The carburetor is connected to the intake port 2Ob through an intake pipe 23a. 2 3 are connected. An exhaust port 20c communicating with the combustion recess 20a is opened on the front surface of the cylinder head 20, and an exhaust pipe 24 is connected to the exhaust port 20c. The exhaust pipe 24 extends obliquely downward and to the right of the engine 2, and extends obliquely rearward and upward below a transmission case 45 described below and to the right of the bulging portion 22 b of the lubricating oil chamber 95. And is connected to a muffler 25 disposed on the right side of the rear wheel 7. An ignition plug 30 is inserted into the combustion recess 20a.

On the left side of the cylinder block 19, there is formed a chain chamber 19a for communicating the inside of the crankcase 22 and the inside of the cylinder head 20, and the chain chamber 19a is provided with the crankshaft. A timing chain 34 for rotatably driving the camshaft 31 by the shaft 28 is provided. The camshaft 31 drives the intake valve 32 and the exhaust valve 33 to open and close.

A piston 26 is slidably inserted into the cylinder bore of the cylinder block 19. A small end 27 b of a connecting rod 17 is connected to the piston 26, and a large end 27 a of the connecting rod is connected to the left and right crank arms of the crankshaft 28. It is connected to a crankpin 29 fitted between 2δa and 28b. A transmission shaft 47 is disposed behind the crankshaft 28 in parallel with the crankshaft 28, and an output shaft 48 is coaxially disposed on the left side of the transmission shaft 47 in the axial direction. ing. A drive sprocket 49 is attached to the left end of the output shaft 48, and the drive sprocket 49 is connected to the driven sprocket 51 of the rear wheel 7 via a chain 50. .

A generator 42 is mounted on the left end of the crankshaft '28. This generator 42 has a sleeve 42 fixed to a sleeve 43 fitted to a crankshaft 28 and a stator 42b opposed to the sleeve 42a. Case 4 The structure is fixed to 4.

The crankcase 22 is divided into a first case 40 on the left side in the crankshaft direction and a second case 41 on the right side. A generator case 44 for accommodating the generator 42 is mounted detachably on the outside of the first case 40 in the direction of the crankshaft, and the stepless case is mounted on the outside of the second case 41 in the direction of the crankshaft. A transmission case 45 accommodating the transmission mechanism 16 is mounted.

The dividing line B of the second and fourth cases 40 and 41 is slightly deviated to the left from the cylinder axis A. The second case 40, 41 supports the crankshaft 28 inside the first and second outer peripheral walls 40a, 41a that open substantially outward in the crankshaft direction. It has a schematic structure in which the second support walls 4Oh and 4Ib are integrally formed.

The first support wall 4 Ob of the first case 40 includes a first crank support wall portion 40 c that supports the left crank journal portion 28 c of the crankshaft 28 via the left journal bearing 35. And a speed reduction mechanism support wall portion 40d which is formed in a stepped bulge on the left side in the crankshaft direction with respect to the first crank support wall portion 40c.

The second support wall 4 1b of the second case 41 has a second crank support wall 4 1c that supports the right crank journal 28 d of the crankshaft 28 via the right journal bearing 36. On the left side in the crankshaft direction with respect to the second crank support wall portion 41c. And a clutch supporting wall portion 41d bulgingly formed in a stepped shape. The crank arms 28a and 28b of the crankshaft 28 and the crank pins 29 are provided in a crank chamber 37 formed by the first and second crank support walls 40c and 4l'c. Is housed.

The centrifugal clutch mechanism 17 is accommodated in a clutch chamber 38 formed by the second outer peripheral wall 41 a and the clutch support wall 41 d, and the clutch chamber 38 is provided in the crank chamber 3. 7 is defined.

Further, the reduction gear mechanism 18 is accommodated in a reduction chamber 39 formed by the reduction mechanism support wall 40 d and the clutch support wall 41 d, and the reduction chamber 39 is provided in the crank chamber 37. Is in communication with

The reduction gear mechanism 18 has a reduction shaft 52 mounted between the support wall portions 40 d and 41 d in parallel with the transmission shaft 47, and a right side portion of the reduction shaft 52 is connected to the clutch support wall. The shaft 41 is supported by the part 41d via the reduction bearing 53, and the left end is supported by the recess 40e formed in the reduction mechanism support wall 40d via the reduction bearing 54. Also, a primary reduction small gear 74 is mounted on the transmission shaft 47 located in the clutch chamber 38 so as to be relatively rotatable, and the primary reduction large gear 75 is combined with the primary reduction small gear 74 on the reduction shaft 52. The secondary reduction small gear 52 is integrally formed on the reduction shaft 52 located in the reduction chamber 39, and the secondary reduction small gear 52 is formed on the output shaft 48. The structure is such that the large secondary reduction gear 48a is integrally formed.

The output shaft 48 is disposed on the same axis as the transmission shaft 47. At the right end of the output shaft 48, a support hole 48b into which the left end of the transmission shaft 47 is inserted is recessed, and a bearing 76 mounted in the support hole 48b is provided. The right end of the output shaft 48 is rotatably supported by the variable speed shaft 47. The left end of the output shaft 48 penetrates the deceleration mechanism support wall 40d of the first case 40, and is supported by the support wall 40d via a bearing 77. . The drive sprocket 49 is fixedly attached to the projecting end of the output shaft 48. The V-belt type continuously variable transmission mechanism 16 has a drive pulley 55 attached to the right outer end of the crankshaft 28 and a driven bully 56 driven rightward of the transmission shaft 47. The pulleys 55 and 56 are attached to each other by a V-belt 57 wound thereon.

The V-belt 57 is made of heat-resistant and durable resin, and has the following structure in detail. For example, a large number of resin blocks 57a formed by mixing a carbon fiber or an aramid fiber into a polyamide resin and forming the same into a horizontal H shape are arranged side by side, and these are connected to a pair of super-heat-resistant rubber annular connecting members. 5 7b is fitted and connected.

The drive pulley 55 includes a fixed pulley half 55 a fixed to the right end portion of the crankshaft 28, and a fixed pulley half 55 a that can slide axially inward in the crankshaft direction. And a movable pulley half 55b arranged to rotate with the crankshaft 28 via a slide collar 59. A cam plate 58 and a slide collar 59 are mounted on the right end of the crankshaft 28 by spline fitting, and the fixed pulley half 55a is mounted on the axially outer side thereof, and a lock nut 60 is mounted. It is tightened and fixed. The movable pulley half 5 5 b and the cam plate 5

8, a cylindrical weight 61 is provided. As the rotation of the crankshaft 28 rises, the weight 61 moves radially outward due to centrifugal force and the movable pulley half

By moving 55b outward in the axial direction, the winding diameter of the pulley increases, and the reduction ratio decreases.

The driven pulley 56 is fixed to the right outer end of the transmission shaft 47 and is fixedly slidable in the axial direction to the outside of the fixed pulley half 56 a in the crankshaft direction. And a movable pulley half 56b. Above fixed pulley half 5

The cylindrical slide collar 6 2 fixed to the shaft center of 6 a is spline-fitted to the speed change shaft 47, and the slide pulley 62 has the shaft center of the movable pulley half 56 b mounted thereon. A cylindrical boss portion 63 fixed to the portion is mounted movably in the axial direction. This The guide bin 64 implanted in the slide collar 62 can slide in the slide groove 63 a formed in a slit shape in the boss portion 63 of the movable pulley, and the movable pulley half 56 b It is engaged to rotate with the fixed pulley half 56a.

A spring receiving member 65 composed of an annular plate is attached to the tip of the slide collar 62 by a circlip 65a. The spring receiving member 65 and the movable plastic half 56b A coil spring 67, which constantly urges the movable pulley half 56b toward the fixed pulley half 56a, is interposed therebetween.

The driven pulley 56 is inserted and disposed so as to be immersed in the distal end 62 a of the slide collar 62, and a lock nut screwed to the distal end 47 a of the transmission shaft 47. The transmission shaft 47 is fixed to the transmission shaft 47 from the point 66. (

Here, the inner diameter of the slide collar 62 is set to be larger in a stepped manner than the outer diameter of the transmission shaft 47, and the tip end 47a of the transmission shaft 47 is set to be a smaller diameter in a stepped manner. I have. As a result, the mouth nuts 66 and the washers 66a can be inserted into the slide collars 62 without hindrance, and thus the lock nuts 66 can be moved from the spring receiving members 65 of the coil springs 67 to the crankshaft. It can be positioned inside the direction.

According to the present embodiment, the movable pulley half 56 b of the driven pulley 56 attached to the speed change shaft 47 is disposed outside the fixed pulley half 56 a in the crankshaft direction. An empty space can be secured in the inner portion of the driven pulley 56, and the centrifugal clutch mechanism 17 can be disposed adjacent to the fixed pulley half 56a by using this empty space. As a result, the output shaft 48 can be coaxially arranged on the counter driven pulley 56 side of the transmission shaft 47 without increasing the engine width. As a result, the conventional output shaft is arranged behind the transmission shaft. The front-rear length of the engine can be shortened compared to the ones.

In this embodiment, the lock nut 66 is fixed to the movable pulley half 56 b. A spring receiving member 6 for supporting a coil spring 67 for urging the pulley half 56 a side is provided. The coil springs 6 are arranged so that they are immersed inward in the axial direction, so that the required length of the coil springs 6 7 can be secured and the protrusion to the outside in the shifting axial direction can be reduced with a simple structure. Can be suppressed.

That is, for example, as shown in FIG. 16, in the case of a structure in which the outer end surface of the slide collar 201 is fastened and fixed to the transmission shaft 200 with the lock nut 203, the lock nut 203 The transmission case 204 protrudes outward in the vehicle width direction by an amount corresponding to that. On the other hand, in the present embodiment, since the lock nut 66 is located axially inward of the outer end of the spring receiving member 65, the protrusion of the transmission case 45 is reduced by t (about 1 Omm). it can.

In addition, since the coil spring 67 is located on the outside in the axial direction, the maintenance and replacement of the coil spring 67 can be performed simply by removing the circlip 65a, which facilitates the work. By the way, when the movable pulley half is placed inside the fixed pulley half, that is, the coil spring is placed inside in the axial direction, the entire driven burley must be removed, and the workability is low.

The transmission case 45 has a substantially hermetic structure formed independently of the crankcase 22. When viewed from the right side (see FIG. 4), most of the upper part of the crankcase 22 is formed. Has an elliptical shape that covers The transmission case 45 is made up of a resin-made case body 45 a having a bottomed box shape that opens outward in the direction of the crank axis and a lid 45 b made of aluminum alloy that airtightly closes the opening. It is fixed together with the second case 41 by bolts 70. A gap a is provided between the bottom wall 45 c of the case body 45 a and the second case 41, and the gap a prevents heat from the engine 2 being transmitted to the transmission case 45. Restrained.

An opening 41 e having a size that allows the centrifugal clutch mechanism 17 to enter and exit is formed outside the second outer peripheral wall 41 a forming the clutch chamber 38 in the axial direction. A clutch cover (clutch other side support wall) 71 is air-tightly mounted in the opening 41 e. The clutch cover 71 is opened by the port 72 to the opening of the second outer peripheral wall 41 a. It is detachably fastened and fixed to the edge. Thus, the transmission case 45 is removed together with the driven pulley 56, and the clutch cover 71 is removed so that the centrifugal clutch mechanism 1 Ί can be removed together with the transmission shaft 47.

The centrifugal clutch mechanism 17 is positioned and clamped so that it cannot move in the axial direction by one-side and other-side clutch bearings 80 and 81 mounted on the left end and the center of the transmission shaft 47 in the axial direction. The one-side clutch bearing 80 is supported by a clutch support wall 41 d, the other-side clutch bearing 81 is supported by the clutch cover 71, and the one-side clutch bearing 80 and The clutch support wall 41d supporting the reduction bearing 53 is deviated to the left in the crankshaft direction from the second crank support wall 41c supporting the right journal bearing 36, in other words, the left side described above. It is located between the first crank support wall 40c supporting the journal bearing 35 and the second crank support wall 41c. More specifically, it is located on the cylinder axis A, or closer to the split line B than the cylinder axis A.

The clutch cover 71 that supports the other-side clutch bearing 81 is located on the right side in the crankshaft direction with respect to the second crank support wall 41 b that supports the right journal bearing 36. Furthermore, the speed reduction mechanism supporting wall 40 d supporting the left bearing 77 of the output shaft 48 is located further to the left outside in the crankshaft direction than the first crank supporting wall 40 c supporting the left journal bearing 35. ing.

According to the present embodiment, since the V belt 57 wound around the driving pulley 55 and the driven pulley 56 is made of resin, the heat resistance and durability of the belt itself are reduced to a rubber belt. The cooling of the V-belt 57 can be eliminated. As a result, the transmission case 45 can be made to have a closed structure, and water and dust can be prevented from entering.

In addition, the use of a highly durable resin belt 57 makes it possible to reduce the outer diameters of the drive and driven pulleys 55 and 56, and to that extent the drive and driven pulleys. The distance between the shafts 55, 56 can be shortened, and the entire engine can be made compact.

In this embodiment, since the transmission case 45 has a closed structure independent of the crankcase 22, engine heat is shut off by the gap a generated between the two cases 22, 45. The heat from the engine 2 is not easily transmitted to the transmission case 45, and the temperature rise in the belt room can be suppressed. Further, heat transmission from the engine side is suppressed because the case body 45a is made of a resin to which heat is hardly transmitted.

The crankcase 12 is divided into first and second cases 40 and 41 in the crankshaft direction, and the transmission case 45 is disposed outside the second case 41 in the crankshaft direction. Since the centrifugal clutch mechanism 17 is arranged near the inner side of the case 45 in the crankshaft direction, the output shaft 48 can be coaxially arranged on the opposite side of the continuously variable transmission mechanism 16 of the transmission shaft 47 from the engine. The dimension in the front-rear direction can be reduced while suppressing an increase in the width dimension of 2.

Also, since the centrifugal clutch mechanism 17 is sandwiched between the one-side and other-side clutch bearings 80 and 81 mounted on the transmission shaft 47, the centrifugal clutch mechanism 17 can be mounted with a simple structure without using separate parts. Can be positioned and supported in any direction.

In this embodiment, the one-side clutch support wall 41 d supporting the one-side clutch bearing 80 is connected to the first and second crank support walls supporting the left and right journal bearings 35, 36 of the crankshaft 28. Clutch cover (clutch other-side support wall) 7 that supports the other clutch bearing 8 1, which is located between 40 c and 1 c, and 2nd crank support wall 4 1 c that supports the right journal bearing 36 The first crank support wall 40c, the clutch one-side support wall 41d and the second crank support wall 41c and the clutch cover 71 are located on the same line. As compared with the case, the volume of the clutch chamber 38 can be secured while shortening the distance between the crankshaft 28 and the transmission shaft 47, and the centrifugal clutch mechanism 17 can be housed in a compact, and as a result, the entire engine To It can be compact.

Also, since the clutch cover 71 is detachably attached to the opening 4 le of the second case 41, the transmission shaft 45 is removed by removing the transmission case 45 and the clutch cover 71.

The centrifugal clutch mechanism 17 can be removed together with 7, making maintenance and parts replacement easier.

In the present embodiment, the output shaft 4δ is arranged coaxially on the anti-transmission case 45 side of the transmission shaft 47, and the drive sprocket 49 is mounted on the output shaft 48. The latch mechanism 17 and the drive sprocket 49 can be arranged coaxially, and the longitudinal dimension of the engine can be reduced.

The centrifugal clutch mechanism 17 is disposed close to and inside the driven pulley 56 in the crankshaft direction. The centrifugal clutch mechanism 17 is of a wet multi-plate type, and as shown mainly in FIGS. 12 to 15, a spline is formed so that the boss 83b of the bowl-shaped clutch 83 rotates together with the transmission shaft 47. The inner clutch 84 was coaxially arranged axially inside the outer clutch 83, and the hub portion 84a of the inner clutch 84 was spline-fitted so as to rotate together with the primary reduction gear 74. It has a schematic structure. The small primary reduction gear 74 is rotatably mounted on the transmission shaft 47.

A plurality of outer clutch plates 85 are arranged in the inner clutch 83, and two pressing plates 86, 86 are arranged at both ends thereof. The outer clutch 83 is engaged with the outer clutch 83 so as to rotate therewith. An inner clutch plate 87 is disposed between the outer clutch plate 85 and the pressing plate 86, and the inner clutch plates 87 are engaged with the outer periphery of the inner clutch 84 so as to rotate together with the inner clutch 84. ing. A cam surface 83 a is formed inside the outer clutch 83, and a weight 88 is disposed between the cam surface 83 a and the outer pressing plate 86. This weight 88 moves radially outward due to the centrifugal force of the outer clutch 83. As a result, the cam surface 83a moves to the left of the drawing in FIG. 12 (clutch connection direction), and the pressing plate 86 is pressed and moved to connect the outer and inner clutch plates 85, 86 to each other. And In FIG. 12, the upper side of the axis of the centrifugal clutch mechanism 17 indicates the disconnected state, and the lower side thereof indicates the connected state.

The centrifugal clutch mechanism 17 is provided with a clutch plate sticking prevention mechanism 90. The sticking prevention mechanism 90 is provided between the outer clutch plates 85 and between the outer clutch plates 85 and the pressing plate 86 to form an adhesive clutch plate 85 and a pressing plate 86. It is configured with a leaf spring 91 urged in the direction of separating from each other.

Pins 92 for regulating the axial movement of the inner clutch plate 87 are inserted through the inner clutch plates 87 at a certain interval in the circumferential direction. A coil spring 93 for urging the inner clutch plates 87 in a direction to separate the inner clutch plates 87 from each other is mounted therebetween.

In the centrifugal clutch mechanism 17 of the present embodiment, the weight 88 moves outward in the clutch radial direction by centrifugal force as the engine rotation increases, and the axial position is determined by the cam surface 83a. When the rotation of the throttle (not shown) causes the engine rotation to reach a predetermined value or more, the weight 88 presses and moves the pressing plate 86 to press the auta and the inner clutch plates 85 and 87 into pressure. As a result, the engine rotation is transmitted from the variable speed shaft 47 to the output shaft 48 via the reduction gear mechanism 18, and the rotation of the output shaft 48 causes the rear wheel 7 via the drive sprocket 49 and the chain 50. It is driven to rotate.

As the engine speed decreases due to the throttle closing operation, the weight δ 8 moves inward in the radial direction, and when the engine speed falls below a predetermined value, the pressing force by the weight 8 8 is released, and the above-mentioned auta and inner clutch plate are released. 85, 87 rotate relative to each other, and engine rotation is cut off between the transmission shaft 47 and the output shaft 48.

When the pressure contact force is released when the clutch is disengaged, the leaf spring 91 The reaction clutch causes the clutch plate 85 and the pressing plate 86 to separate from each other, and the reaction force of the coil spring 93 causes the inner clutch plates 87 to separate from each other.

This can prevent the auta and inner clutch plates 85, 87 from sticking to each other due to lubricating oil, and prevent the clutch from dragging.

In addition, since the axial movement of the inner clutch plate 87 is restricted by each pin 92, it is possible to prevent the inner crack plate 87 from tilting when the clutch is disengaged, and in this respect, to prevent the clutch dragging phenomenon. .

Next, the lubricating oil system of the engine 2 will be described.

In this lubricating oil system, the lubricating oil in a lubricating oil chamber 95 formed in the bottom 22 a of the crankcase 22 is sucked by an oil pump 96 and the bearings of the crankshaft 28 and camshaft 31 and The lubricating oil is lubricated by lubricating the lubricating part and returned to the lubricating oil chamber 95 by gravity.

The oil pump 96 is disposed mainly below the first case 40 of the crankcase 22, as shown in FIG. 11, and more specifically, the anti-transmission case of the lubricating oil chamber 95. It is attached to the inner surface 22c located on the 45th side. The oil pump 96 has a pump shaft 96a supported by a housing 97 having a suction port 97a and a discharge port 97b, and a pump gear 98 mounted on an outer end of the pump shaft 96a. It has a structured structure.

The first case 40 is provided with a suction passage 40 f communicating with the suction port 97 a, and the suction passage 40 f is provided on the bottom surface in the lubricating oil chamber 95 via an oil strainer 99. It is open to. Further, a lubricating oil supply passage 40 g communicating with the discharge port 97 b is formed in the first case 40. The supply passage 40 g communicates with a main supply passage 44 a formed in the generator case 44 via an oil filter 100 on the way, and is connected to the main supply passage 44 a. The downstream end is connected to an oil chamber 44c communicating with the left end face of the crankshaft 28.

The crankshaft 28 has an oil passage 28 e communicating with the oil chamber 44 c. The oil passage 28 e is formed in the direction of the center, and the oil passage 28 e is connected to a connecting bearing portion 101 of the crank pin 29 and the connecting rod 27 via a branch passage 29 a formed in the crank pin 29. It is open to.

The lubricating oil sucked by the oil pump 96 is supplied under pressure to the oil passage 28 e through the supply passage 40 g and the main supply passage 44 a, and from the oil passage 28 e through the branch passage 29 a. It is supplied to the connecting bearing 101. The lubricating oil supplied to the connecting bearing portion 101 is scattered into the crank chamber 37 by the supplied hydraulic pressure and the centrifugal force of the crankshaft 28, and a part of the scattered lubricating oil is reduced by the deceleration chamber. 39, lubricating the secondary reduction small gear 52a and large gear 48a, and then falls into the lubricating oil chamber 95.

The lubricating oil chamber 95 is provided at the bottom 22 a of the crankcase 22.

37 is formed below the transmission case 45, and a bulging portion 22b is formed so as to protrude below the transmission case 45 (FIGS. 8, 11). reference)

. The bulging portion 22b is formed so as to be located within the projection plane of the transmission case 45 when viewed from a plane. The center line D of the lubricating oil chamber 95 in the vehicle width direction is from the cylinder axis A. It is deviated to the above transmission case 45 side.

According to the present embodiment, since the bulging portion 22b is formed so as to be located below the transmission case 45 at the bottom portion 12a of the crankcase 22, an empty space below the transmission case 45 is formed. It is possible to increase the amount of lubricating oil in the lubricating oil chamber 95 by effectively utilizing the space, and it is necessary to make the height of the engine 2 larger than when the case bottom is deepened to secure the amount of lubricating oil. Absent.

In addition, since the bottom portion 22 a of the crankcase 22 is bulged below the transmission case 45, the surface area of the lubricating oil chamber 95 can be increased, and the cooling performance can be improved accordingly, and the entire engine can be further improved. Weight balance can be improved.

Here, in this embodiment, the V-belt 57 is made of resin and the transmission case

4 5 is made independent of the crankcase 2 2 so a rubber belt is used. The heat resistance and the durability of the belt itself can be increased as compared with the case where the belt itself is used, and the influence of the original heat can be suppressed. As a result, the drive and driven pulleys 55, 56 can be reduced in diameter, the transmission case 45 can be reduced in size, and an empty space can be provided below the transmission case 45. As a result, the swollen portion 22b was formed to increase the lubricating oil capacity.

Next, the lubricating structure of the centrifugal clutch mechanism 17 will be described.

As shown in FIGS. 3 and 7, the centrifugal clutch mechanism 17 scatters lubricating oil from the bearing 101 connected to the connecting rod 27 and the crank pin 29 when viewed in a direction perpendicular to the crankshaft. It is located so as to partially overlap the area. Specifically, the aft of the centrifugal clutch mechanism 17 and the inner clutch plates 85, 87 are arranged at positions facing the crank chamber 37.

The second outer peripheral wall 41 a defining the crank chamber 37 and the clutch chamber 38 has an inlet opening through which lubricating oil scattered from the connecting bearing 101 is introduced into the clutch chamber 38. 103 are formed.

Further, a guide portion 104 extending inside the clutch chamber 38 is formed on the clutch support wall portion 41d. The guide portion 104 is located on an extension line connecting the crankshaft 28 and the transmission shaft 47, and has a lubricating oil receiving portion 104 a extending in the vertical direction so as to substantially face the introduction opening 103. The lubricating oil receiving portion 104 has a guide portion 104 b extending in an arc shape so as to extend below the transmission shaft 47 following the lower end of the lubricating oil receiving portion 104 a. The guide portion 104 b is positioned so as to be inserted into a boss portion of the inner clutch 84 having a truncated cone shape.

As a result, the lubricating oil that has entered from the introduction opening 103 is received by the guide portion 104 and is guided more to the inner portion than the outer periphery of the centrifugal clutch mechanism 17. As a result, the above lubricating oil is supplied between the outer and inner clutch plates 85, 87, and is also supplied to the joint between the primary reduction large gear 75, and the small gear 74 (see arrows in FIGS. 3 and 7). See). 3/04468

19 According to the centrifugal clutch mechanism lubrication structure of the present embodiment, the lubricating oil supplied to the coupling bearing portion 101 between the crank pin 29 and the large end portion 27 a of the condole is supplied to the centrifugal clutch mechanism 17. As a result, a large amount of lubricating oil spouted and scattered from the connecting bearing part 10 i can be supplied to the centrifugal clutch mechanism 17, eliminating the need for a special lubricating oil path and providing a sufficient amount of lubricating oil. It can be supplied to the centrifugal clutch mechanism 17 to prevent seizure of the auta and inner clutch plates 85, 87.

In the present embodiment, when the centrifugal clutch mechanism 17 is viewed in the clutch chamber 38 defined from the crank chamber 37 and in a direction perpendicular to the crankshaft, the lubricating oil scattering area from the coupling bearing portion 101 is viewed. And the second peripheral wall 41 a defining the clutch chamber 38 and the crank chamber 37 is formed with an introduction opening 103 that allows the entry of lubricating oil. The lubricating oil from the crankcase 37 can be effectively introduced into the clutch chamber 38 with a simple structure.

In the present embodiment, a guide portion 104 extending inward of the clutch chamber 38 is integrally formed with the clutch support wall portion 41d, and the guide portion 104 is connected to the crankshaft 28 and the transmission shaft 47. A lubricating oil receiving portion 104 a that is located on an extension line connecting the lubricating oil and extends substantially in opposition to the introduction opening 103, and a lower end of the transmission shaft 47 following the lower end of the lubricating oil receiving portion 104 a The lubricating oil can be more reliably supplied to the auta and the inner clutch plates 85, 87 because the guide portions 104b extend in an arc shape so as to be turned around. Next, the kick device of the engine 2 will be described.

Mainly, as shown in FIGS. 5, 9, and 10, a kick shaft 110 is disposed substantially vertically below the output shaft 48 in parallel with the output shaft 48. When viewed in the direction perpendicular to the crankshaft, the kick shaft 110 has a portion inside the drive sprocket 49, which is supported by a boss 4Oh of the first case 40, and a portion outside the generator. It is supported by a pair of bosses 4 4 b formed on the cover 44.

A kick arm 111 is attached to the outer end of the kick shaft 110. A kick gear 1 1 2 is provided at the inner end of the kick shaft 1] 0 so that it can slide in the axial direction. The kick gear 111 is located in the first case 40. A return spring 113 is wound around the inner end of the kick shaft 110, and the return spring 113 biases the kick shaft 110 to the depressed position. Between the kick shaft 110 and the crankshaft 28, the main intermediate shaft 114 and the sub intermediate shaft 1

15 are arranged in parallel with the kick shaft 1 10 respectively. The main intermediate shaft 1 1 4 is supported by being bridged between the first case 40 and the second case 41.

A main intermediate gear i 16 which can be combined with the kick gear 11 1 is mounted on 14. The sub intermediate shaft 1 15 is supported by a bearing portion 40 j formed in the first case 40. The inner and outer ends of the sub intermediate shaft 115 project inside and outside the first case 40, respectively. A first intermediate gear 1 15a is formed inside the case of the sub intermediate shaft 1 15 to be combined with the main intermediate gear 1 16 and a second intermediate gear 1 17 is formed outside the case. It is installed. A first crank gear 121 described later is combined with the second intermediate gear 117.

When the kick arm 111 is depressed, the kick shaft 110 rotates, and with the rotation, the kick gear 112 moves in the axial direction to engage with the main intermediate gear 116, and 2 The power is transmitted to the first crank gear 121 through the intermediate gears 115a and 117, and the crankshaft 28 rotates.

Between the left journal bearing 35 of the crankshaft 28 and the sleeve 43 of the generator 42, a one-way clutch 120, the first crank gear (first driving gear) 1 2 in order from the outside. 1, Force Musket 1 2 2 is installed.

The one-way clutch 120 is provided with a starting gear 120a, and the starting gear 120a is provided with a drive gear 1 25 of a star motor 125 through an idler gear 124. a is connected. The starter motor 125 is arranged and fixed to the front wall of the crankcase 12 with the motor axis oriented parallel to the crankshaft 28.

The kick gear 1 1 2, the main intermediate gear 1 16, and the first intermediate gear 1 15 a Is disposed at a position in communication with the lubricating oil chamber 95 inside the first case 40. Further, the second intermediate gear 117, the first crank gear 121, and the force spring 122 are arranged outside the first case 40.

According to the kick device of the present embodiment, since the kick gear 1 12, the main intermediate gear 1 16, and the first intermediate gear 1 15 a are located in a portion communicating with the lubricating oil chamber 95, these Can sufficiently lubricate the joints of the gears.

Further, the main intermediate shaft 1 15 is penetrated from the inside to the outside of the first case 40, and the rotation of the kick shaft 110 is transmitted from the inside to the outside of the main intermediate shaft 1 15 to the second intermediate Since the gear 1 17 is transmitted to the crankshaft 28 via the first crank gear 1 1 1, the first crank gear 1 2 1 can be arranged outside the crank journal section 28 c, and the crank bearing 3 The distance between 5, 36 can be reduced, and the crankshaft 28 can be supported by reducing the bending moment by the condole 27. Furthermore, a space for arranging the cam sprocket 122 and the second crank gear 127 can be secured, and the layout around the crank shaft can be easily performed. That is, when the rotation of the kick shaft 110 is transmitted to the crankshaft 28 in the first case 40, a gear is required between the left crank bearing 35 and the left crank arm 28a. The distance between the left and right bearings 35, 36 increases, which is disadvantageous for the bending moment.

In the present embodiment, since the kick shaft 110 is disposed substantially below the output shaft 48 in the vertical direction, the kick arm 111 can be easily depressed, and the front and rear dimensions of the engine 2 can be reduced. Can be.

The inside of the kick shaft 110 in the rear wheel drive sprocket 49 in the vehicle width direction is supported by the first clutch support wall 40 d of the crank case 22, and the outside in the vehicle width direction is the generator case 4. Since the kick arm 111 is attached to the outwardly protruding end of the generator case 44 of the kick shaft 110, the kick shaft 110 and, consequently, the kick arm 111 are mounted on the rear wheel. It can be arranged at the optimum stepping position without interfering with the drive sprocket 49. As shown in FIG. 4, the kick shaft 110 is located in the axial projection plane of the transmission case 45 and the centrifugal clutch mechanism 17 when viewed in the crankshaft direction. positioned. More specifically, it is arranged so as to be located substantially vertically below driven pulley 56.

Since the kick shaft 110 is arranged on the opposite side of the transmission case 45 in this manner, there is no need to secure a kick shaft arrangement space in the transmission case 45, and therefore the stepless transmission mechanism 16 The drive pulley 55 and the driven pulley 56 can be arranged so close to each other that a slight gap b (see FIG. 3) is generated, and the longitudinal length of the engine can be reduced accordingly.

In addition, since the kick shaft 110 is arranged on the projection plane of the transmission case 45 in the crankshaft direction, the kick shaft 110 can be arranged at a position close to the crankshaft 28 and at a position where it can be easily depressed. it can.

In the present embodiment, the centrifugal clutch mechanism 17 is disposed near the inside of the driven pulley 56 in the crankshaft direction, and the kick shaft 110 is positioned in the axial projection plane of the centrifugal clutch mechanism 17, and Since the kick shaft 110 is disposed substantially vertically below the transmission shaft 47, the kick shaft 110 can be disposed at a position where the pedal can be easily depressed by utilizing an empty space in the projection plane of the centrifugal clutch mechanism, and the engine 2 The front and back length of / J can be reduced.

Above and behind the crankshaft 28, a balancer shaft 29 is disposed in parallel with the crankshaft 28. The balancer shaft 1229 is supported by the first and second cases 40 and 41 via balancer bearings 130 and 131, respectively. The left end portion of the balancer shaft 127 projects outward from the first case 40, and a balancer gear 132 is coupled to the projection. A damper member 133 is provided on the inner peripheral portion of the balancer gear 132.

Here, the left and right crank arms 28 a and 28 b of the crankshaft 28 are located within the above balancer bearings 130 and 1331, and the balance weight of the balancer shaft 119 is located. The reference numeral 129a is disposed between the left and right crank arms 28a, 28b and close to the crankshaft 28 so as to overlap the rotation locus of the crankpin 29. This makes the area around the balancer axis compact.

A second crank gear (second drive gear) 127 is mounted on the first crank gear (first drive gear) 121 press-fitted into the crankshaft 28 so as to rotate together. The balancer gear (second driven gear) 13 2 is connected to the second crank gear 1 I 7. Further, a second intermediate gear 117 of a kick gear train that transmits the rotation of the kick shaft 110 to the crank shaft is combined with the first crank gear 121. Further, a pump gear 98 of the lubricating oil pump 96 is connected to the first crank gear 122 via the second intermediate gear 117. That is, the second intermediate gear 117 is shared as a part of the pump gear train and the kick gear train.

More specifically, the first crank gear 1 21 is a cylindrical one having outer teeth (external gear) 1 2 a formed on the outer peripheral surface, and has a thickness more than twice that of other plate gears. And is firmly press-fitted and fixed to the outer periphery of the crankshaft 28. The second crank gear 127 has an annular shape in which an inner peripheral tooth (internal gear) 127 a and an outer peripheral tooth (external gear) 127 b are formed on an inner peripheral surface and an outer peripheral surface. The second crank gear 117 is mounted so as to cover the engaged portion (right end) of the first crank gear 121, and its inner peripheral teeth 127a are attached to the first crank gear 122. It is fitted to the outer peripheral teeth 1 2 a of 1 (see Fig. 6). Thus, the rotation of the crankshaft 28 is transmitted from the first crank gear 122 to the balancer gear 132 via the second crank gear 127.

Here, the outer diameter of the first crank gear 1 2 1 is equal to the outer rim 3 5 b of the left crank journal bearing 35 formed in the first case 40. It is set to a smaller diameter. As a result, the operation for assembling the crankshaft 28 into the crankcase 22 can be realized with a simple structure. That is, with the second crank gear 127 removed, the first case 40 is moved from left to right to fit the support hole 35a into the left crank journal bearing 35a. 2 crank gear 1 2 7 is fitted to the first crank gear 1 2].

In addition, the one-way clutch 120 mounted on the crankshaft 28, the first crank gear 12 and the cam sprocket 122 tighten the nut 123 screwed to the left end of the crankshaft 28. As a result, the sleeve 43 and the journal bearing 35 are sandwiched so as not to move in the axial direction.

According to the present embodiment, the cylindrical first crank gear 1 21 is press-fitted and fixed to the crankshaft 28, so that the press-fit length of the first crank gear 1 11 1 to the crankshaft 28 is reduced. Thus, the first crank gear 111 can be firmly fixed to the crankshaft 2δ.

In addition, the rotation of the crankshaft 28 is transmitted from the first crank gear 111 firmly fixed thereto to the pump gear 98, and the rotation of the kick shaft 110 is transmitted via the first crank gear 122. Since the torque is transmitted to the crankshaft 28, the torque transmitted between the crankshaft 28, the lubricating oil pump 96, and the kickshaft 110 can be reliably transmitted.

Also, the second crank gear 127 is arranged so as to overlap the engaged portion (right end) of the first crank gear 121, so that the first crank gear 122 has a sufficient press-fit length. When the length in the direction of the crankshaft is increased while forming a cylindrical shape that can be secured, the problem can be avoided.

Also, the structure is such that the inner peripheral teeth 1 27 a of the second crank gear 127 are detachably fitted to the outer teeth 1 211 a of the first crank gear 121, so that the second crank gear 127 Can be easily attached and detached.

Also, the outer diameter of the first crank gear 1 2 1 is set smaller than the inner diameter of the outer edge 35 b of the crankcase side support hole 35 a of the adjacent crank journal bearing 35, so the crank case 22 is divided into left and right. With this structure, the crankshaft 28 can be easily assembled in the crankcase with a simple structure. That is, when assembling the crankshaft 28, the first case 40 is removed with the second crank gear 127 removed. By moving the bearing support hole 35a into the crank journal bearing 35 by moving it inward in the axial direction, the support between the crankcase 22 and the crankshaft 28 is assembled. .

By removing the generator 42 and the one-way clutch 120 mounted outside the first and second crank gears 121 and 127 of the crankshaft 28, the second crank gear 127 can be removed. Can be removed axially outward. Thus, the second crank gear 127 can be easily assembled and removed. Since the balancer shaft 1 29 driven by the second crank gear 127 is always rotating at the same speed as the engine rotation, it may be a source of noise. Since it can be replaced, it is easy to realize a combination of the second crank gear 127 and the balancer gear 132 with less noise during engine assembly.

Also, the second intermediate gear 1 17, which is coupled to the first crank gear 1 2 1, transmits the rotation of the kick shaft 1 10 to the crank shaft 28, and the rotation of the crank shaft 28 to the pump gear 98. Since it is shared with the transmission, the crankshaft length can be shortened accordingly, the engine width can be made compact, and the required number of gears and gear shafts can be reduced.

In addition, the inner peripheral teeth 1 17 a of the second crank gear 127 are fitted to the first crank gear 121 press-fitted to the crankshaft 28, and the second intermediate gear 117 is fitted. As a result, the press-fit length of the first crank gear 1 2 1 into the crankshaft 28 can be sufficiently ensured, and the rotation of the crankshaft 28 can be ensured by the pump gear 98 and the balancer gear 1 32 Can be transmitted.

In the present embodiment, a structure is employed in which the outer peripheral teeth 121 a of the first crank gear 121 and the inner peripheral teeth 117 a of the second crank gear I 17 are employed. 1 27 is easy to assemble and can be easily removed for maintenance. That is, by removing the nut 123 of the crankshaft 28 and removing the sleeve 43 and the one-way clutch 120, the second crank gear 1 I7 is moved to the first crank. It can be easily removed from the rank gear 1 2 1.

Here, in the above-described embodiment, the first drive gear has outer peripheral teeth (external gears) over its entire length. However, the engaged portion of the first drive gear is an outer spline, (2) The drive gear may have an inner spline on its inner peripheral surface, and both splines may be fitted. In this case, since the formation of the internal gear is not required, the manufacture of the second drive gear is facilitated.

Further, as for the engagement structure between the first drive gear and the second drive gear, as shown in FIG. 17, the engaged portion 1 2 1b of the first drive gear 12 1 It is also possible to machine the shaft shape of the second drive gear 127 and the engaging portion 127c of the second drive gear 127 into a hole shape with a circular cross section, respectively, and to connect them with the key 127d. . Further, as shown in FIG. 18, flat portions 12 1 c and 17 e are formed on the outer surface of the second drive gear and the inner surface of the shaft hole, and the outer flat portions 1 2 1 c and I 2 7e may be engaged, and other various structures can be adopted. When the above-described engagement structure is adopted, it is desirable to locate the engagement portion on the generator side for the convenience of attaching and detaching the second drive gear 127.

Each shaft of the engine 2 of the present embodiment has the following arrangement structure.

When viewed in the crankshaft direction, the transmission shaft 47 and the output shaft 48 are disposed on the substantially same horizontal plane behind the crankshaft 28. Above the horizontal plane C including the axis of the crankshaft 28 and the output shaft 48, the balancer shaft 12 9 and the reduction shaft 52 are arranged, and the kick shaft 1 10 and the pump shaft 9 6 are arranged below. a, main and sub intermediate shafts 114 and 115 are arranged.

The kick shaft 110 is arranged substantially vertically below the output shaft 48, and the pump shaft 96a is arranged substantially vertically below the balancer shaft 129. Further, the main and sub intermediate shafts 114 and 115 are arranged on a line connecting the crankshaft 28 and the kick shaft 110.

According to the present embodiment, above the horizontal plane C including the crankshaft 28 and the output shaft 48 The I 7 noiser shaft 1 29 is arranged, and the kick shaft 110 and the oil pump 96 shaft 96 a are arranged below, so that these can be arranged well above and below with good balance. The engine can be prevented from becoming larger. That is, there is an empty space above the horizontal plane C and behind the cylinder bore, and the balancer shaft 129 is arranged using this space. Since the weight 12a of the balancer shaft 1229 rotates with a large rotation trajectory, the loss horsepower due to the lubricating oil agitation increases when the balancer 1129 is immersed in the lubricating oil. The shaft 1 29 does not diffuse the lubricating oil. The deceleration shaft 52 is disposed above the horizontal plane C by utilizing an empty space between the balancer shaft 12 9 and the output shaft 48. In this case, the lubricating oil is located at the upper part where it is difficult to supply the lubricating oil.However, the lubricating oil scattered from the connecting bearing 101 of the crankshaft 28 is supplied to the reduction gear 75 etc. No problem.

In addition, since the kick shaft 110 is disposed substantially below the output shaft 48 in the vertical direction, the front-rear length of the engine 2 can be reduced, and the kick shaft 110 can be easily depressed. Can be arranged. Industrial applicability

According to the invention of claim 1, the first drive gear is fixedly mounted on the crankshaft, and the second drive gear is detachably engaged with the engaged portion of the first drive gear. Therefore, more specifically, as in the invention of claim 2, the first drive gear is press-fitted and fixed to the crankshaft, and the second drive gear is attached to the engaged portion (end) of the outer peripheral teeth of the first drive gear. The inner peripheral teeth of the gear are detachably fitted to each other so that the rotation of the crankshaft is transmitted from the first drive gear to the first driven gear and from the first drive gear to the second driven gear via the second drive gear. As a result, the length of the first drive gear fixed to the crankshaft, specifically, the press-fit length can be sufficiently secured, and the rotation of the crankshaft can be reliably transmitted to the second driven gear. . The second drive gear is disposed so as to overlap the engaged portion of the first drive gear, so that even if the press-fit length of the first drive gear is sufficiently ensured, the crankshaft direction is not changed. The problem can be avoided when the direction length increases.

According to the third aspect of the present invention, the engaged portion of the first drive gear is formed as an outer spline, the inner spline is formed on the inner peripheral surface of the second drive gear, and both splines are fitted. There is no need to form an internal gear on the inner peripheral surface of the motor, and the manufacture of the second drive gear is easy.

According to the invention of claim 4, since the outer diameter of the first drive gear is set to be smaller than the inner diameter of the crankcase-side support hole of the adjacent crank journal bearing, the crankcase is divided into left and right parts. The crankshaft can be easily assembled in the crankcase with a simple structure. That is, when assembling the crankshaft, the left and right split crankcases are moved in the crankshaft direction with the second drive gear removed, and the bearing support holes of the crankcase are fitted to the crank journal bearings. By doing so, the support part of the crankcase and the crankshaft is assembled. According to the invention of claim 5, the crankshaft part mounted outside the first and second drive gears of the crankshaft is removed. Sometimes, the second drive gear can be removed to the outside in the axial direction, so that it is easy to assemble and remove the second drive gear. For example, if the noise from the second drive gear is loud, separate it. The work when replacing with a new one can be performed easily.

In the invention of claim 6, since the kick gear train is combined with the first drive gear, and the balancer gear train is combined with the second drive gear, the I drive in which the rotation from the cook shaft is firmly fixed to the crank shaft is provided. It can be reliably transmitted to the crankshaft via the gear. Since the balancer shaft driven by the second drive gear always rotates at the same speed as the engine rotation, it may be a noise source.However, since the second drive gear can be easily replaced, noise during engine assembly is reduced. It is easy to realize a combination of a drive gear and a driven gear that generate less.

In the invention of claim 7, both the pump gear train and the kick gear train share a partially common gear. Since this is combined with the first drive gear through the above, the length of the crankshaft can be shortened accordingly, and the required number of gears and the number of gearshafts can be reduced.

Claims

The scope of the claims

1. Between the crankshaft and the second driven shaft, the first drive gear and the second drive gear on the crankshaft side and the first driven gear and the second driven gear on the second and the second driven shaft are connected. In the engine transmitting torque through the first drive gear, the first drive gear is fixedly mounted on the crankshaft, and the second drive gear is attached to the first drive gear by the first drive gear. The engaging portion is removably engaged with the engaging portion, and the transmission of rotational force between the crankshaft and the first driven shaft is performed by the first driving gear and the first driven gear. The transmission of the rotational force between the crankshaft and the second driven shaft is performed between the first driving gear and the first driven gear via the second driving gear. An engine characterized by that.

2. The first drive gear according to claim 1, wherein the first drive gear has a cylindrical shape having outer peripheral teeth (external gears) formed on an outer peripheral surface thereof, and is fixed to the crankshaft by press-fitting. Is an annular member having an inner peripheral surface and an outer peripheral surface formed with inner peripheral teeth (internal gear) and outer peripheral teeth (external gear). The inner peripheral teeth are engaged with the outer peripheral teeth of the first drive gear. An engine characterized by being detachably fitted to a joint portion.

3. The first drive gear according to claim 1, wherein the first drive gear has a cylindrical shape having outer peripheral teeth (external gears) on an outer peripheral surface thereof and an outer spline following the outer gears, and is fixed to the crankshaft by press-fitting. The second drive gear has an annular shape having inner splines and outer teeth (external gears) on inner and outer peripheral surfaces, and the inner spline is attached to and detached from the outer spline of the first drive gear. An engine which is fitted as possible.

4. An outer diameter of the first drive gear according to any one of claims 1 to 3, wherein the outer diameter of the first drive gear is set to be smaller than an inner diameter of a crankcase-side support hole of an adjacent crank journal bearing. An engine characterized in that the crankcase-side support hole can be fitted to the crank journal bearing in a state where the crank journal bearing is removed.

5. The crankshaft component according to any one of claims 1 to 4, wherein a crankshaft component is detachably mounted outside the first and second drive gears of the crankshaft. An engine wherein the second drive gear is detachable from the crankshaft when the engine is removed.

6. In any one of claims 1 to 5, the first drive gear is combined with a kick gear train that transmits the rotation of a kick shaft to a crankshaft, and the second drive gear is rotated by the rotation of the crankshaft. The engine is characterized in that a balancer gear train transmitting torque to the balancer shaft is engaged.

7. In claim 6, the first drive gear includes a pump gear train transmitting the rotation of the crankshaft to a lubricating oil pump and the kick gear train transmitting the rotation of the kick shaft to the crankshaft. An engine wherein a part of the kick gear train and a part of the pump gear train are shared.