JP3590212B2 - Transmission unit for vehicle engine unit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine unit for a vehicle, and more particularly to an assembling structure of a shift mechanism of a transmission.
[0002]
[Prior art]
For example, as an engine unit mounted on a motorcycle, a unit case in which a crankshaft and an input shaft and an output shaft of a transmission are respectively accommodated and arranged in parallel in a unit case formed integrally with a crankcase and a transmission device case. is there. In such an engine unit, a structure is adopted in which a shift mechanism including a shift fork, a fork shaft, a shift drum, and the like of a transmission can be easily assembled. For example, it is common to form an assembling opening in a side wall and a top wall of the crankcase facing the shift mechanism, and assemble the shift mechanism using the side wall opening and the top wall opening. In this case, a dedicated lid member is attached to the side wall opening, and an oil breather chamber that is also used as a lid member is attached to the top wall opening (for example, see Japanese Patent Application No. 63-266941). ).
[0003]
[Problems to be solved by the invention]
However, in the conventional transmission assembling structure, an opening for assembly is also formed in the top wall of the crankcase, so that a lid member is required, and the number of processing steps of the mating surface of the top wall opening is reduced. This requires a lot of man-hours for assembling the lid member, resulting in a problem that the cost is increased, and also a problem that the rigidity of the crankcase is reduced by the opening of the top wall.
[0004]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional circumstances, and provides a transmission apparatus for an engine unit for a vehicle that does not require an opening for assembling a top wall of a crankcase and can suppress an increase in cost and a decrease in rigidity. It is an object.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, the crankshaft 21 and the output shaft 74 of the transmission 70 are arranged on the plane of the crankcase 25, and the input shaft 72 of the transmission 70 is spaced apart from the plane of the crankcase 25. The shift drum 90, the input fork shaft 91 for supporting the input shift fork 93, and the output fork shaft 92 for supporting the output shift fork 94 in parallel with the input shaft 72 and the output shaft 74. In the transmission 70 of the vehicle engine unit 15 disposed so as to face outward from the assembly opening 26 a formed on the side surface of the input shaft 25, the input-side shift fork 93 is slid on the input gear mounted on the input shaft 72. The stopper for restricting the rotation angle of the input side shift fork 93 when the input side shift fork 93 is rotated around the input shaft 72 by engaging with the moving groove 71b It is characterized in that across the input shaft 72 of the case 25 is formed in the counter-min ratio side.
[0006]
According to a second aspect of the present invention, in the first aspect, the stopper portion adjusts the rotation angle of the input-side shift fork 93, the guide groove 90a of the shift drum 90 when the engagement pin 93a of the shift fork 93 is in the normal position. It is characterized in that it is restricted to an angle that deviates from.
[0007]
According to a third aspect of the present invention, in the first or second aspect, the stopper is constituted by a bottom wall 26c of an oil breather chamber 96 formed in the crankcase 25.
[0008]
Operation and Effect of the Invention
The assembling work of the transmission of the vehicle engine unit of the present invention is performed in the following procedure. First, the upper case 26 constituting the crankcase is placed so that the dividing surface faces upward, and the input shaft 72 on which the input gear group is mounted is inserted through an insertion hole or the like formed in the side wall of the upper case 26. And is mounted in the upper case 26.
[0009]
Next, the claw portion of the input side shift fork is engaged with the sliding groove of one of the gears of the input gear group from the opening of the distribution surface of the upper case 26, and the input side shift fork is moved around the input shaft. When the base of the shift fork is brought into contact with the stopper by being rotated downward, the rotation angle position of the input-side shift fork is thereby regulated.
[0010]
Next, the shift drum is inserted and arranged from the assembly opening side, and the engagement pin of the input side shift fork is engaged with the guide groove of the shift drum, and in this state, the input side fork shaft is connected to the input side fork from the assembly opening side. Insert
[0011]
As described above, according to the transmission of the vehicle engine unit according to the first aspect of the present invention, since the stopper portion that regulates the rotation angle of the input side shift fork about the input shaft is formed in the crankcase, the input is made as described above. The side shift fork can be temporarily supported while being locked to the input shaft, and the input side fork shaft is inserted from the assembly opening side of the crankcase side surface to form an assembly opening in the top wall of the crankcase. The assembly of the input side shift fork and the fork shaft can be realized without the need. As a result, it is possible to eliminate the need for the conventional cover member for opening the ceiling wall, the mating process thereof, and the man-hour for attaching the cover member, thereby reducing costs and avoiding a reduction in rigidity of the crankcase.
[0012]
According to the invention of claim 2, the rotation angle of the input side shift fork by the stopper portion is set at a position where the engagement pin of the input side shift fork is disengaged from the guide groove of the shift drum. With the temporary holding state, the shift drum can be inserted from the assembly opening side without any trouble, and there is an effect that the assembly operation can be further facilitated.
[0013]
According to the third aspect of the present invention, since the stopper is constituted by the bottom wall of the oil breather chamber formed in the crankcase, it is not necessary to form the stopper specially, thereby reducing costs and simplifying the structure. This has the effect of avoiding an increase in size.
[0014]
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 17 are diagrams for explaining an engine unit of a motorcycle according to an embodiment of the present invention. FIG. 1 is a left side view of the motorcycle on which the engine unit is mounted, and FIGS. FIG. 5 is a cross-sectional view showing a communication hole portion of a cylinder block, and FIGS. 6 to 8 are a plan view, a cross-sectional side view, and a cross-sectional side view of a cylinder head, respectively. Figures 9 and 9 are side sectional views of the head bolt portion, Figure 10 is a plan view of the camshaft, Figures 11 and 12 are left side views and a sectional rear view of the transmission, and Figures 13 and 14 are cooling water and lubrication. FIG. 15 is a rear view of the starting device, and FIGS. 16 and 17 are a plan view and a schematic configuration diagram of an intake device. Note that the terms front and rear, left and right in this embodiment refer to front and rear, left and right when viewed in a state of sitting on a seat.
[0015]
In FIG. 1, reference numeral 1 denotes a motorcycle, and a vehicle body frame 2 has a structure in which a seat rail 4 extending rearward of the vehicle body is connected to the rear ends of a pair of left and right main frames 3 having a substantially inverted L shape in side view. A fuel tank 5 is mounted on the upper part of the main frame 3, and a main seat 6 and a tandem seat 7 are mounted on the upper part of the seat rail 4, respectively.
[0016]
A front fork 9 is pivotally supported by a head pipe 8 at a front end of the main frame 3, and a front wheel 10 is pivotally supported at a lower end of the front fork 9. A rear arm 11 is pivotally supported by a pivot shaft 12 on a rear arm bracket 3a below the rear end of the main frame 3 so as to be vertically swingable. A rear wheel 13 is supported by the rear end of the rear arm 11. .
[0017]
A rear cushion 14 is provided between the rear arm 11 and the body frame 2. The lower end of the rear cushion 14 is connected to the lower end of a first link 14a which is erected on the rear side and is supported by the rear arm 11, and the upper end is supported by the body frame. The upper end of the first link 14a is connected to the vehicle body frame via a second link 14b provided upright on the rear side of the rear cushion 14, and the second link 14b and the first link 14a are connected to the rear cushion 14. Is forming a triangle. As described above, since the lower end of the rear cushion 14 is supported by the first and second links 14a and 14b which are arranged upright, a large space is secured below the rear cushion 14 while ensuring so-called progressive characteristics. ing.
[0018]
An engine unit 15 is suspended below the main frame 3, and a radiator 16 is disposed in front of the engine unit 15. The engine unit 15 is a water-cooled 4-cycle, parallel 4-cylinder, 5-valve engine having a cylinder axis 20 inclined forward and a crankshaft 21 directed in the vehicle width direction.
[0019]
As shown in FIGS. 2 to 4, the engine unit 15 has a cylinder head 23 stacked on the upper surface of the cylinder block 22 and fastened with head bolts, and a head cover 24 is mounted on the upper surface of the cylinder head 23. In addition, it has a schematic structure in which a unit case 25 in which a crankcase and a transmission device case are integrated is formed under the cylinder block 22.
[0020]
The unit case 25 is divided into upper and lower cases 26 and 27, and the upper case 26 is formed integrally with the cylinder block 22. The crankshaft 21 is supported by bearings 30 on a plurality of bosses 29 formed on the surface of the upper and lower cases 26 and 27. Further, the crank chamber 19 for each cylinder is independent by the boss portion 29. An oil pan 28 is connected to a lower mating surface of the lower case 27.
[0021]
Four cylinder bores (cylinders) 22a are formed in the cylinder block 22 in parallel, and a piston 31 is slidably inserted into each cylinder bore 22a. A small end of a connecting rod 32 is connected to the piston 31 via a piston pin 31b, and a large end of the connecting rod 32 is connected to a crankpin 21a of the crankshaft 21. The piston 31 is of a so-called slipper type in which a notch concave portion 31c is formed in a shaft end portion of a piston pin 31b of a piston skirt 31a.
[0022]
Three intake ports 33 and two exhaust ports 34 are opened in a combustion recess 23 a formed on the surface of each of the pistons 31 facing the pistons 31 of the cylinder head 23, and each opening can be opened and closed by an intake valve 35 and an exhaust valve 36. It has become. At the upper end of each of the valves 35, 36, a bottomed cylindrical valve lifter 37, 37 is mounted. The valve lifter 37 is slidably supported by a lifter guide hole 23b formed in the cylinder head 23. A spring 38 is provided between each of the valves 35 and 36 and a spring seat 23c formed in the cylinder head 23 to constantly bias the valves in the closing direction.
[0023]
Above the intake valve 35 and exhaust valve 36, camshafts 40 and 41 for pressing and driving the valves are arranged in parallel with each other and in parallel with the crankshaft 21. The camshafts 40 and 41 are housed and arranged in a camshaft arrangement chamber 39 formed by the cylinder head 23 and the head cover 24, and are fixed to the cam bearing portion formed on the cylinder head 23 by bolting. And is rotatably supported by the cam cap 48.
[0024]
Further, the cam sprockets 40a, 41a attached to the right ends of the camshafts 40, 41 in the axial direction and the cam drive teeth 21b integrally formed at the right end of the crankshaft 21 are connected by a timing chain 42. The cam sprockets 40a, 41a, the timing chain 42, and the cam driving teeth 21b of the camshaft driving mechanism configured as described above are integrated with the cylinder block 22 and the right outer end face of the cylinder head 23 in a chain arrangement chamber (cam). (Shaft drive mechanism arrangement chamber) 43. A rotor 44 having outer peripheral teeth is mounted inside the cam driving teeth 21b of the crankshaft 21, and a pickup 45 for detecting a crank rotation angle is opposed to the rotor 44. Reference numeral 46 denotes an automatic tensioner for automatically adjusting the tension of the timing chain 42, and reference numeral 47 denotes a chain guide.
[0025]
An opening 50 for assembling the camshaft drive mechanism is formed in a portion of the outer wall 22b of the cylinder block 22 constituting the chain arrangement chamber 43 facing the crankshaft 21, and the opening 50 is provided with a cover member 51. Are detachably bolted. When viewed in the crankshaft direction, a communication hole 52 communicating the adjacent crank chambers 19 is formed through the lower portion of the cylinder bore 22a located in the assembling opening 50 so as to form the same axis.
[0026]
Each of the communication holes 52 is formed by machining from the assembling opening 50 to reduce the pumping loss due to the reciprocating motion of the piston. A hard plating film a is formed on the inner surface of each of the cylinder bores 22a in order to enhance wear resistance. This plating film a is formed by masking the communication hole portion before forming the communication hole 52 and performing plating processing in this state, thereby facilitating the plating process operation and improving the communication hole. 52 is facilitated.
[0027]
That is, the plating process is performed by closing the upper and lower openings of the cylinder bore 22a and energizing while the plating solution is filled in the closed space, but the communication hole 52 is formed first. And the above-mentioned blockage becomes difficult. On the other hand, if machining is performed after plating, the hard plating film a makes processing difficult. In the present embodiment, since the plating process is performed in a state where the communication hole 52 is masked, the above-described problem can be avoided.
[0028]
As shown in FIG. 5, a lubricating oil passage 53 that connects the bearing 30 of the crankshaft 21 and the inner peripheral surface of the communication hole 52 is formed in each boss 29 of the upper case 26. A cooling nozzle 54 is inserted into the lubricating oil passage 53, and an injection port 54a of the nozzle 54 is directed from the notch concave portion 31c of the piston 31 located at the bottom dead center to the back surface of the piston. The thickness of the communication hole 52 in the crankshaft direction is W2 on the crankshaft side and W1 on the piston side. Therefore, the lubricating oil injected from the injection port 54a is reliably supplied to the piston back surface without being hindered by the periphery of the communication hole 52 or the piston skirt, and the piston 31 can be reliably cooled.
[0029]
Next, the fastening structure of the cylinder head 23 will be described.
6 to 10, bolt insertion holes 23d are formed in the cylinder axial direction on the intake side and the exhaust side of the portion between the cylinders of the cylinder head 23, and are implanted in the cylinder block 22 in the bolt insertion holes 23d. The upper end of the provided head bolt 55 is located.
[0030]
A washer mounting surface 56 is formed on the upper edge of the bolt insertion hole 23d of the cylinder head 23, and a washer 57 having a diameter slightly smaller than the washer mounting surface 56 is mounted on the mounting surface 56. ing. The cylinder head 23 is fastened and fixed to the cylinder block 22 via the washer 57 by screwing nuts 58 and 59 to the head bolt 55. The nut 58 on the intake side has a smaller diameter than the washer 57, whereas the nut 59 on the exhaust side has the same diameter as the washer 57.
[0031]
Here, if the inter-cylinder dimension is reduced in order to reduce the size of the engine, it becomes difficult to secure a nut mounting space for the head bolt 55. Particularly, since three lifter guide holes 23b are required on the intake side, the wall thickness necessary for the rigidity of the guide holes 23b is secured while reducing the inter-cylinder dimension, and the area required for the washer mounting surface 56 is secured. Is difficult to secure.
[0032]
In the present embodiment, the following structure is adopted to secure the wall rigidity while narrowing the dimension between cylinders and to secure a necessary washer arrangement area. Above the suction side washer mounting surface 56 of the cylinder head 23, a washer rotating hole 60 is formed in a bag shape following the mounting surface and having a diameter slightly larger than the washer 57 and capable of rotating the washer 57. The washer arrangement surface 56 and the washer rotation hole 60 are located below the lower edge of the lifter guide hole 23b when viewed in the height direction.
[0033]
On the upper side of the washer rotation hole 60, a nut insertion hole 61 is formed to have a smaller diameter than the washer rotation hole 60 and a slightly larger diameter than the nut 58, and the nut insertion hole 61 is formed in the camshaft arrangement chamber. 39 is open. A slit 63 having a diameter slightly larger than that of the washer 57 is formed on the inner surface of the nut insertion hole 61. The slit 63 is formed so as to pass through the center of the nut insertion hole 61 and to be perpendicular to the cam shaft 40, and is set to have substantially the same radial length as the washer rotation hole 60.
[0034]
In this manner, the washer 57 is inserted from the slit 63 in a state of being oriented vertically and at right angles to the cam shaft, and is rotated in the washer rotation hole 60 to be seated on the washer mounting surface 56 (FIG. 8, FIG. 8). (See FIG. 9). The exhaust-side nut insertion hole 62 has a slightly larger diameter than the washer 57, and the nut 59 has a pressing surface having the same diameter as the washer 57.
[0035]
Here, of the head bolts 55, the axis of the head bolts 55, 55 on the intake side and the exhaust side between the cylinders are separated from the axes of the cam shafts 40, 41 on the intake side and the exhaust side when viewed from a plane. That is, it is slightly offset outward away from the center of the cylinder bore.
[0036]
Since the inter-cylinder head bolt 55 is offset outward from the camshaft axis in this manner, the wall thickness of the lifter guide hole 23b can be secured while reducing the inter-cylinder dimension.
[0037]
On the other hand, the head bolt 55 located at the end on the chain arrangement chamber 43 side is arranged so as to coincide with the cam axis. Unlike the head bolt between the cylinders, the head bolt 55 disposed at this end is not narrowed by the lifter guide holes 23b, 23b, so that it can be disposed closer to the chain arrangement 43 side. The wall thickness of the lifter guide hole 23b 'can be secured without offsetting from the axis.
[0038]
Here, the torsional torque acting on the camshafts 40 and 41 is maximum at the end on the cam chain arrangement chamber 43 side, and decreases as the distance from the arrangement chamber 43 increases. On the other hand, as described above, the inter-cylinder head bolt is offset outward from the camshaft axis, while the head bolt at the end of the chain arrangement chamber 43 coincides with the camshaft axis. 64 is offset outwardly from the camshaft axis, while the tool hole 64 'at the end coincides with the camshaft axis.
[0039]
As described above, since the tool hole 64 'provided at a position where the torsion torque is large is made to coincide with the camshaft axis, the torsional rigidity of the camshaft due to the tool hole 64' can be suppressed. Further, among the tool holes for the inter-cylinder head bolts, the tool holes near the cam chain arrangement chamber 43 are offset from the camshaft axis, which is disadvantageous in terms of torsional rigidity. However, a thrust receiving portion 65 is provided as described later. Therefore, the above reduction in torsional rigidity can be covered. The remaining tool holes do not pose a problem because the torsion torque is small.
[0040]
Each of the camshafts 40 and 41 is integrally formed with a thrust receiving portion 65 having a predetermined axial width to restrict the axial movement thereof. The thrust receiving portion 65 is formed to have a larger diameter than other portions except the cam nose. The thrust receiving portion 65 is formed vertically above the head bolt 55 between the first and second cylinders located at the outermost ends of the camshafts 40 and 41 on the chain arrangement chamber 43 side (FIG. 6). reference). A tool hole 64 is formed through the thrust receiving portion 65 in the diameter direction. The tool hole 64 is formed so as to be coaxial with the head bolt 55. A similar tool hole 64 is formed in a portion of each of the camshafts 40 and 41 facing the other head bolt 55. Further, a tool hole 48a is formed in a portion facing each tool hole 64 of the cam cap 48, and a plug (not shown) is provided in the tool hole 48a provided at a position corresponding to a bearing portion adjacent to the cam chain. It is detachably inserted.
[0041]
Here, the thrust receiving portion is usually formed in a flange shape having a small axial width, but in this embodiment, the thrust receiving portion 65 is formed to have a large axial width, thereby forming the tool hole 64. As a result, the torsional rigidity of the camshaft is prevented from lowering.
[0042]
Here, when assembling the cylinder head 23 to the cylinder block 22, first, the intake and exhaust valves 34, 35, the spring 38, and the valve lifter 37 are assembled to the cylinder head 23, and the washers 57, nuts 58, 59 are attached to the washer placement surface 56. The cylinder head 23 is so-called sub-assembled by inserting the camshafts 40 and 41 and the cam cap 48 and then assembling them.
[0043]
Then, the sub-assembled cylinder head 23 is placed on the cylinder block 22, a fastening tool is inserted from the tool hole 48 a and the tool hole 64, and the nuts 58 and 59 are fastened to the head bolt 55. The camshafts 40 and 41 may be assembled after the cylinder head 23 is fastened to the cylinder block 22.
[0044]
As shown in FIG. 6, the camshaft bearings 66, 66 at the end of the cylinder head 23 on the side of the chain arrangement chamber 43 are formed wider in the axial direction than the other bearings. A nut insertion hole 67 is formed in the bearing 66. The nut insertion hole 67 is formed offset from the bearing center line E toward the lifter guide hole 23b in the cam shaft direction. Further, an oil passage 128 communicating the oil passages 127 and 129 on the intake side and the exhaust side is offset from the bearing center line E to the side opposite to the lifter guide hole 23b ', that is, in the direction perpendicular to the camshaft toward the chain arrangement chamber 43 side. It is formed so as to extend. Accordingly, the durability of the bearing portion 66 to which a large radial load is applied can be ensured while forming the nut insertion hole 67, and the oil passage 127 that connects the intake side and the exhaust side can be formed without any trouble.
[0045]
Next, the transmission 70 of the engine unit 15 will be described.
The transmission 70 includes a main shaft (input shaft) 72 on which an input gear group 71 is mounted above a rear portion of the crankshaft 21, as shown mainly in FIGS. 2, 4, 11, and 12. Drive shafts (output shafts) 74 each having an output gear group 73 meshing with the input gear group 71 mounted below the shaft 72 are arranged in parallel with the crankshaft 21.
[0046]
The drive shaft 74 is supported via a bearing 75 on a boss formed on the surface of the upper and lower cases 26 and 27 in the same manner as the crankshaft 21. The main shaft 72 is disposed in the upper case 26, and the left end of the main shaft 72 is supported by a boss of the upper case 26 via a bearing 76. The right side portion is supported by a right side wall 26g of the upper case 26 via a bearing 77 and a flange 78, and the flange 78 is fixed to the right side wall 26g by bolting.
[0047]
The left end of the drive shaft 74 protrudes outward from the unit case 25, and a drive sprocket 79 mounted on the protrusion is connected to the rear wheel sprocket 13a of the rear wheel 13 via a chain 80. At the right end of the main shaft 72, a clutch mechanism 81 is mounted. The clutch mechanism 81 meshes with a small reduction gear 82 of the crankshaft 21 and is spline-coupled to the outer drum 84, which is coupled via a damper to a large reduction gear 83 supported by the main shaft 72, and a spline coupling to the main shaft 72. It has a structure in which a number of clutch plates 86 are interposed between the inner drum 85 and the clutch plate 86. The clutch mechanism 81 is turned off the engine power by rotating a push lever 87 connected to the inner drum 85.
[0048]
A shift drum 90, an input-side fork shaft 91, and an output-side fork shaft 92 are disposed in parallel with the main shaft 72 and the drive shaft 74 on the rear obliquely upper rear side thereof. , 92 are supported by right and left bosses 26e, 26f formed integrally with the upper case 26. Note that a bearing 90c is provided between the left end of the shift drum 90 and the left boss 26f. Reference numeral 90d denotes a retaining plate for the bearing 90c and the fork shafts 91 and 92. In FIG. 11, the retaining plate 90 is removed.
[0049]
One input-side shift fork 93 is mounted on the input-side fork shaft 91, and two output-side shift forks 94, 94 are mounted on the output-side fork shaft 92 movably in the axial direction. The bifurcated claws 93b, 94b of the shift forks 93, 94 are slidably engaged with sliding grooves 71b, 73b formed in the gears of the input gear group 71 and the output gear group 73, respectively. Engagement pins 93a, 94a formed integrally with the bases of 93, 94 are slidably engaged with guide grooves 90a formed on the outer peripheral surface of the shift drum 90. By rotating the shift drum 90 by a change mechanism (not shown), the two shift forks 93 and 94 slide in the axial direction to move the gears of the input gear group 71 and the output gear group 73. As a result, Switching is performed between the lowest speed stage and the highest speed stage.
[0050]
An assembly opening 26a is formed in a portion of the left side wall of the upper case 26 that faces the shift drum 90, the input side fork shaft 91, and the left end of the output side fork shaft 92, and a cover plate is formed in the assembly opening 26a. 95 (see FIG. 1) is detachably mounted.
[0051]
An oil breather chamber 96 is formed integrally with an upper portion of the upper case 26 for separating lubricating oil mixed in air discharged from the inside of the crankcase to the outside for adjusting the pressure in the crankcase. Have been. The air from which the lubricating oil has been separated is introduced into the intake system. The bottom wall 26c of the oil breather chamber 96 is located near the upper side of the input-side fork shaft 91, and regulates the rotation angle of the fork 93 when assembling the input-side shift fork 93, as described later. It is a stopper.
[0052]
Next, a procedure for assembling the transmission 70 will be described.
{Circle around (1)} First, the upper case 26 is turned upside down so that the distribution surface faces upward, and is placed on an assembly table or the like. Then, the main shaft 72 in which the input gear group 71 is incorporated is inserted from the right wall opening 26d of the upper case 26 through the insertion hole of the right wall 26g, and the left end is fitted into the bearing 76 and the flange 78 is attached. Tighten the bolt to the right side wall 26g (see FIGS. 2, 4, and 12).
[0053]
{Circle around (2)} Next, the claw portion 93b of the input side shift fork 93 is engaged with the sliding groove 71b of one gear of the input gear group 71 from the distribution surface side, and is rotated around the claw portion 93b. The base 93c is brought into contact with the bottom wall 26c of the oil breather chamber 96. As a result, the input side shift fork 93 is maintained in the state shown by the two-dot chain line in FIG. 11 without disengaging the engagement of the claw portion 93b with the sliding groove 71b. At this time, the engagement pin 93a is located slightly outside the outer peripheral surface of the shift drum 90.
[0054]
{Circle around (3)} Next, the shift drum 90 is inserted into the drum support hole of the left boss portion 26f from the assembly opening 26a of the left wall, and the right end (tip portion) 90b is fitted into the support hole of the right boss portion 26e. The shift drum 90 is set by fitting the left end bearing 90c into the support hole of the left boss portion 26f. At this time, since the rotation angle position of the base 93c of the input side shift fork 93 is held so that the engagement pin 93a does not interfere with the outer peripheral surface of the shift drum 90, the shift drum 90 can be inserted without any trouble. It is.
[0055]
(4) Then, the base 93c of the input shaft side shift fork 93 is rotated upward to engage the engaging pin 93a thereof in the guide groove 90a of the shift drum 90. The fork shaft 91 is inserted into the shift fork 93 from the assembly opening 26a side, and both ends of the input fork shaft 91 are fitted into the support holes of the left and right bosses 26f, 26e of the upper case 26. Thus, the assembly of the main shaft 72 and the input-side shift fork 93 is completed.
[0056]
(5) Next, the drive shaft 74 in which the output gear group 73 is incorporated and the claw portions 94b, 94b of the output shaft side shift forks 94, 94 are engaged with the sliding grooves 73b, 73b is moved to the output shaft side shift. The engagement pin 94a of the fork 94 is placed on the distribution surface of the upper case 26 while being engaged with the guide groove 90a of the shift drum 90. In this state, the output-side fork shaft 92 is inserted through the assembling opening 26a into the shift fork 94, and both ends of the fork shaft 92 are fitted into the support holes of the left and right boss portions 26f, 26e of the upper case 26. . Finally, a retaining plate 90d is attached, and a link mechanism is connected to the left end of the shift drum 90. After setting the shift forks 94, 94, the drive shaft 74 may be mounted.
[0057]
Next, the positional relationship between the crankshaft 21, the main shaft 72, and the drive shaft 74 will be described mainly with reference to FIG. The main shaft 72 has an acute first axis angle θ1 formed by the crankshaft / main shaft straight line A connecting the shaft center of the main shaft and the shaft center of the crankshaft 21 and the cylinder axis 20 on the cylinder head side and the main shaft side. In other words, it is arranged at a position closer to the cylinder head 23 side than a straight line C passing through the axis of the crankshaft 21 and perpendicular to the cylinder axis 20.
[0058]
In the drive shaft 74, a main shaft / drive shaft straight line B and a crank shaft / main shaft straight line A connecting the shaft center of the drive shaft 74 and the main shaft 72 are formed on the drive shaft side and the crank shaft side. The second axis angle θ2 is arranged to be an acute angle. In this manner, the main shaft 72 and the drive shaft 74 are arranged so as to be carried on the back surface of the cylinder block 22.
[0059]
The maximum outer peripheral surface (the outer peripheral surface of the large reduction gear) 81a of the clutch mechanism 81 is located closer to the cylinder head 23 than a straight line D passing through the top surface of the piston 31 'located at the bottom dead center and making a right angle with the cylinder axis 20. are doing. The main shaft 72, the shift drum 90, the fork shafts 91 and 92, and the drive shaft 74 are located in the axial projection plane of the large reduction gear 83 of the clutch mechanism 81.
[0060]
Next, the arrangement of the cooling water pump and the lubricating oil pump will be described.
As shown mainly in FIGS. 2, 13 and 14, the cooling water pump 100 and the lubricating oil pump 101 of the present embodiment are both housed in the lower case 27, and the pump shaft 102 common to both pumps is It is arranged below and in parallel with the crankshaft 21 and the drive shaft 74. The pump shaft 102 is rotatably supported in the housing unit 103 via bearings 104 and 105. The rotor 106 of the lubricating oil pump 101 is provided at the right end of the pump shaft 102, and the cooling water is provided at the left end thereof. The impeller 107 of the pump 100 is fixed. A driven sprocket 108 is fixed to the right end face in the axial direction of the pump shaft 102 with bolts. The driven sprocket 108 is connected to a driving sprocket 110 mounted on a portion of the main shaft 72 outside the flange 78 via a chain 109. Have been.
[0061]
The housing unit 103 has a three-part structure including a main body 103a located at the center in the axial direction, a cooling housing 103b and a lubricating housing 103c located on the left and right sides. 103c is fastened to the main body 103a by bolts 111, 112 screwed in the axial direction. The maximum diameter portion 103d of the housing unit 103 is disposed at a position radially opposed to the highest speed gear 73a (see FIG. 4) having the minimum diameter of the output gear group 73 of the drive shaft 74.
[0062]
When the housing unit 103 is arranged so as to be close to the main shaft 72, the largest diameter portion 103d is arranged so as to radially face the smallest diameter gear of the input gear group 71 of the main shaft 72. It is desirable to do.
[0063]
Here, the housing unit 103 is accommodated in the lower case 27 and fits and supports the cooling-side housing portion 103b to a boss portion 27a formed on the left side wall of the lower case 27 via an O-ring 27b. The lubrication-side housing portion 103c is fixed to the lower case 27 by being fastened to the vertical wall of the lower case 27 by two bolts 113, 113 screwed from below. The vertical wall extends in a substantially vertical direction from the vicinity of the mating surface with the upper case, and functions as a rib for improving the rigidity of the case.
[0064]
A seal member 114 is provided on the left side of the left bearing 104 of the pump shaft 102 in the axial direction, and a mechanical seal 115 is provided on the left side of the seal member 114 at intervals. A drain hole 116 is formed between the seal member 114 at the bottom of the main body 103a and the mechanical seal 115, and a drain pipe (drain pipe) 117 is inserted into the drain hole 116. The lower end of the drain pipe 117 communicates outward through a drain passage 28a formed in the oil pan 28. Thereby, the water leaking from the cooling water pump 100 is discharged to the outside of the engine. The drain pipe 117 is provided between the housing unit 103 supported by the lower case 27 and the oil pan 28 attached to the lower case from below via the O-ring 117a without using a special support member. It is pinched.
[0065]
A cooling water return hose 118 is connected to the suction port 103e of the cooling side housing portion 103b, and a cooling water supply pipe 119 is connected to the discharge port 103f. The cooling water supply pipe 119 is led out to the front of the engine, and is connected to a cooling jacket inlet (not shown) on the front wall of the cylinder block 23 via a cooling hose 123a and a water supply pipe 123b. Therefore, the space between the outlet of the supply pipe 119 from the pump to the front wall of the engine passes through the inside of the crankcase 25, and the part exposed to the outside, the cooling hose 123a, and the water supply pipe 123b are short, so that the appearance of the engine is improved. .
[0066]
An oil strainer 120 disposed in the oil pan 28 is connected to a lubricating oil suction port 103g of the lubricating side housing portion 103c, and a lubricating oil discharge port 103h is connected to a front wall of the lower case 27. The oil filter 121 is connected in communication. The lubricating oil that has left the oil filter 121 passes through a main gallery 122 and is supplied to engine lubrication sections such as the crankshaft 21, the main shaft 72, the drive shaft 74, and the camshafts 40 and 41.
[0067]
Here, the camshaft path of the lubricating oil is, as shown in FIGS. 3, 6 to 8 and 16, the first oil opening between the first cylinder intake side of the cylinder head 23 and the chain arrangement chamber 43. The discharge port 126 a of the passage 126 communicates with a first oil passage 127 extending along the intake-side camshaft 40, and communicates with a fourth oil passage 129 extending along the exhaust-side camshaft 41 through a third oil passage 128. The first and fourth oil passages 127 and 129 are connected to a camshaft bearing. The lubricating oil that has lubricated the camshafts 40 and 41 is recovered into the oil pan 28 through an oil return passage 130 formed between the exhaust sides of the third and fourth cylinders of the cylinder head 23.
[0068]
In the above embodiment, the cooling water pump and the lubricating oil pump are integrated and arranged in the clan case. However, only the cooling water pump may be arranged in the crank case.
[0069]
Next, a starting device of the engine unit 15 will be described mainly with reference to FIGS. The starting motor 135 is arranged in parallel with the crankshaft 21 on the back surface of the cylinder bore of the upper case 26. The motor 135 is supported by fixing the rear end support portion 135a of the motor 135 to the upper case 26 with bolts and fitting the front end boss portion 135b into the boss portion of the upper case 26.
[0070]
The output gear 136 of the starter motor 135 projects into the upper case 26, and meshes with the large-diameter gear 138a of the intermediate gear 138. The intermediate gear 138 is supported by an intermediate shaft 137 which is bolted and fixed above the main shaft 72 in the upper case 26. The intermediate shaft 137 is connected to a maximum diameter portion of the clutch mechanism 81 (the large reduction gear 83). ) Is located in the axial projection plane.
[0071]
The small-diameter gear 138b of the intermediate gear 138 meshes with a starting gear 139. The starting gear 139 is connected to a boss portion of the large reduction gear 83 supported by the main shaft 72 via a one-way clutch 140. ing. The one-way clutch 140 is configured to transmit the torque from the starting motor 135 to the large reduction gear 83 and not to transmit the torque from the crankshaft 21 to the starting motor 135.
[0072]
The exhaust device of the engine unit 15 mainly includes an exhaust pipe 141 connected to each exhaust port 34 opening to the front wall of the cylinder head 23, between the engine unit 15 and the rear wheel 13, and below the rear cushion 14. It comprises a first muffler 142 arranged and a second muffler 143 arranged on the upper right side of the rear wheel 13.
[0073]
Each of the exhaust pipes 141 is bent downward from the exhaust port 34 and extends rearward below the oil pan 28. The first muffler 142 is arranged by utilizing a space created by arranging the rear cushion link mechanism between the oil pan 28 and the rear wheel 13 upright. Is provided with a silencing mechanism and a catalyst (not shown).
[0074]
Next, the intake device of the engine unit 15 will be described mainly with reference to FIGS. Each intake port 33 led to the rear wall of the cylinder head 23 is connected to a four-way carburetor unit 151 via a joint 150. This carburetor unit 151 is obtained by unitizing first to fourth carburetors 151a to 151d corresponding to the first to fourth cylinders from the right side. Each of the carburetors 151a to 151d is an automatic variable venturi type having a butterfly type throttle valve 152 that opens and closes by a throttle operation, and a piston valve (not shown) that automatically opens and closes by negative pressure of the intake air of the engine. The respective valve shafts 153 of the throttle valve 152 are connected to each other by a connecting member 154 so as to be able to transmit a rotational force.
[0075]
A throttle opening sensor 155 for detecting the opening of the throttle valve 152 is connected to the right end of the carburetor unit 151 in the vehicle width direction. The opening sensor 155 is connected to the chain arrangement chamber 43 side of the cylinder head 23. That is, it is arranged so as to be located on the back of the right protruding portion of the chain arrangement chamber 43. A throttle pulley 156 is mounted on a connecting member 154 between the first carburetor 151a and the second carburetor 151b, and the throttle pulley 156 is connected to a throttle handle (not shown) of a steering handle via a throttle cable 157. (Shown). Each of the throttle valves 152 is opened and closed in synchronization with the rotation of the throttle grip.
[0076]
Here, the carburetor unit 151 has the same dimension W1 from the vehicle center line L to the right outer end of the throttle opening sensor 155 and the same dimension W2 from the vehicle body center line L to the left outer end of the carburetor unit 151. It is arranged to become. As a result, the center line L of the vehicle body coincides with the center line of the carburetor unit 151 in the vehicle width direction.
[0077]
The axes X1 and X2 passing through the centers of the intake passages of the first and second carburetors 151a and 151b and being parallel to the vehicle center line L pass through the cylinder axis 20 of the first and second cylinders, respectively. Are slightly (specifically, about 2 mm) offset toward the chain arrangement chamber 43 from the axes Y1 and Y2, which are parallel to. On the other hand, the axes X3 and X4 of the third and fourth carburetors 151c and 151d are closer to the chain arrangement chamber 43 than the corresponding axes Y3 and Y4 of the third and fourth cylinders. It is larger than the vessels 151a and 15b. Specifically, the third vaporizer 15c is offset by about 7 mm, and the fourth vaporizer 15d is offset by about 14 mm. The throttle pulley 156 causes the pitch between the carburetors to be increased. In the present embodiment, the throttle pulley 156 is disposed between the first and second carburetors whose pitch is increased by the offset. I have.
[0078]
Next, the operation and effect of the present embodiment will be described.
In the present embodiment, the communication hole 52 for communicating the crank chambers 19 is located in the mounting opening 50 of the camshaft drive mechanism provided on the outer wall 22b of the cylinder block 22 when viewed in the crankshaft direction. The communication hole 52 can be formed by machining using the assembling opening 50, and there is no need to perform extra processing such as separately forming an opening for machining. Therefore, it is not necessary to close the processing opening with the exclusive lid member, and the manufacturing cost can be reduced.
[0079]
Further, in forming the hard plating film on the inner surface of the cylinder bore 22a, the plating process is performed prior to the machining of the communication hole 52, so that the plating operation can be facilitated and the processing of the communication hole 52 can be facilitated. Work can be facilitated. That is, the plating process is performed by closing the upper and lower openings of the cylinder bore 22a and supplying an electric current with the plating solution filled in the closed space. If so, the above-mentioned blockage becomes difficult. On the other hand, if machining is performed after the plating treatment, the working becomes difficult due to the hard plating film. In the present embodiment, since the plating process is performed in a state where the communication hole 52 is masked, the above-described problem can be avoided.
[0080]
In the case where the lubricating oil passage 53 is formed in each boss portion 29 of the upper case 26 so as to open to the inner peripheral surface of the communication hole 52 and the lubricating oil is injected through the passage 53 to the back surface of the piston, Since the width W1 of the upper portion of the communication hole 52 is smaller than the width W2 of the lower portion, the injected lubricating oil is reliably supplied to the back surface of the piston without being interrupted by the upper edge of the communication hole 52. Therefore, it is not necessary to cut out the injection passage in the crank chamber wall, and the piston 31 can be efficiently cooled without increasing the cost.
[0081]
Furthermore, in the present embodiment, a slipper-type piston 31 in which a notch recess 31c is formed in the piston skirt 31a is employed, and the notch recess of the piston 31 in which the injection port 54a of the lubricating oil passage 53 is located at the bottom dead center. Since it is directed to the back surface of the piston through 31c, the injection flow of the lubricating oil is not interrupted by the piston skirt 31a, and the cooling efficiency can be improved from this point as well. In addition, since the notch recess 31c is provided, the problem that the effective area of the communication hole 52 is reduced by the piston skirt 31a can be avoided. Alternatively, it is not necessary to lengthen the connecting rod in order to avoid area reduction due to the skirt.
[0082]
According to the cylinder head fastening structure of the present embodiment, the washer mounting surface 56 is formed below the lower edge of the lifter guide hole 23b of the cylinder head 23, and the washer having a larger diameter than the washer 57 following the mounting surface 56. A rotation hole 60 is formed, a nut insertion hole 61 into which a nut 58 can be inserted is formed following the washer insertion hole 60, and a slit having substantially the same radial dimension as the washer rotation hole 60 is formed in the nut insertion hole 61. Since the washer 63 has been formed, the washer 57 can be seated on the mounting surface 56 by inserting the washer 57 from the slit 63 in a vertically oriented state and then falling down the washer rotating hole 60. As a result, the dimensions between the adjacent lifter guide holes 23b can be reduced while securing the necessary wall thickness of the lifter guide portion and the area of the nut tightening seat surface, whereby the cylinder pitch can be reduced and the engine width can be made compact. it can.
[0083]
In this embodiment, when the camshafts 40 and 41 are formed through the tool holes 64 for tightening the head bolts disposed between the cylinders, portions of the camshafts 40 and 41 close to the chain arrangement chamber 43, that is, twisting. Since the tool hole 64 formed at the position where the torque increases and the formation position of the wide thrust receiving portion 65 are matched, the reduction of the torsional rigidity of the camshaft due to the formation of the tool hole 64 is wide and large. The diameter can be suppressed by the thrust receiving portion 65.
[0084]
In the transmission of the present embodiment, the bottom wall 26c of the oil breather chamber 96 formed in the upper case 26 is used as a stopper for restricting the rotation angle position of the input side shift fork 93. The assemblability of the input side shift fork 93 can be improved without an increase and a complicated structure.
[0085]
That is, as described in the above-described assembling procedure, when the input side shift fork 93 is rotated downward while the claw portion 93b is engaged with the slide groove 71a of the main shaft 72, the base portion 93c is moved to the bottom. Since the engaging pin 93a of the shift fork 93 is engaged with the guide groove 90a of the shift drum 90 from the assembly opening 26a side of the upper case 26, since the engaging pin 93a of the shift fork 93 is temporarily held in contact with the wall 26c. It can be assembled by inserting the input-side fork shaft 91. Conventionally, an opening for assembling was formed in the top wall of the crankcase. However, in the present embodiment, such an opening can be eliminated, and the number of processing steps, the cover member, and the number of assembling steps for the opening are unnecessary. In addition, the cost can be reduced, and the rigidity of the ceiling portion of the crankcase can be prevented from lowering due to the formation of the assembly opening.
[0086]
Further, the height position of the bottom wall 26c of the oil breather chamber 96 functioning as the stopper portion is set at a position where the locking pin 93a of the input side shift fork 93 is disengaged from the guide groove 90a of the shift drum 90. The shift drum 90 can be inserted from the assembly opening 26a side without any trouble while the 93 is temporarily held, and the assembly work can be easily performed from this point as well.
[0087]
Further, since the stopper portion is constituted by the bottom wall 26c of the oil breather chamber 96 formed integrally with the upper case 26, it is not necessary to form the stopper portion specially, thereby avoiding an increase in cost and an increase in the size of the case.
[0088]
According to the present embodiment, the crankshaft 21, the main shaft 72, and the drive shaft 74 are connected to the first shaft angle θ1 between the crankshaft / main shaft straight line A and the cylinder axis 20; Since the second shaft angle θ2 between the drive shaft straight line B and the drive shaft straight line B is arranged so as to form an acute angle, the distance between the crankshaft 21 and the drive shaft 74 can be reduced, and the length of the engine unit 15 in the front-rear direction can be shortened accordingly. it can.
[0089]
Since the front and rear length of the engine unit can be reduced, the rear arm pivot part can be located forward, and when the wheel base is set as before, the length of the rear arm 11 can be extended, and the vertical swing angle of the rear arm can be reduced accordingly And running stability can be improved. When the length of the rear arm is set to be the same as the conventional one, the wheelbase can be shortened, and the maneuverability can be improved.
[0090]
Further, since the length of the rear arm 11 can be set large, an empty space can be secured between the engine unit 15 and the rear wheel 13, and the first muffler 142 can be disposed by effectively using the space. As a result, the exhaust noise silencing effect can be improved, and the center of gravity can be reduced.
[0091]
In this embodiment, as shown in FIG. 1, the second muffler 143 is connected to the rear of the first muffler 142 via the exhaust pipe 144. However, depending on the capacity of the first muffler, the second muffler is omitted. It is also possible.
[0092]
Further, since the main shaft 72 is arranged closer to the cylinder head 23 side than the right-angled straight line C passing through the crankshaft 21, the main shaft 72 is arranged to be carried on the back of the cylinder block 22, and The length can be further reduced. Further, since the clutch mechanism 81 is disposed such that the maximum outer peripheral surface 81a thereof is located on the cylinder head 23 side with respect to the right-angled straight line D passing through the piston top surface at the bottom dead center, the engine unit 15 can be downsized also from this point.
[0093]
Since the main shaft 72, the shift drum 90, the fork shafts 91 and 92, and the drive shaft 74 are arranged in the axial projection plane of the maximum diameter portion of the clutch mechanism 81, the arrangement of each shaft is compact, and the unit case 25 The protrusion can be reduced, and the engine can be downsized in this respect as well.
[0094]
In the present embodiment, both the cooling water pump 100 and the lubricating oil pump 101 are arranged in the common housing unit 103, and the housing unit 103 is accommodated and arranged in the unit case 25, so that the protrusion from the crankcase side wall is eliminated. The engine width can be reduced, and the bank angle can be set large.
[0095]
Further, since the largest diameter portion 103d of the housing unit 103 is radially opposed to the highest-speed gear 73a having the smallest diameter of the drive shaft 74, the distance between the pump shaft 102 and the drive shaft 74 can be reduced. Can be downsized.
[0096]
The left end of the housing unit 103 in the axial direction was fitted to the boss portion 27a of the lower case 27 via an O-ring 27b, and the right end was fixed to the lower case 27 by bolts to support the cantilever. Therefore, the fixing bolts can be reduced while securing both the mounting strength and the sealing property without applying a radially uneven load, thereby reducing the cost and simplifying the mounting structure.
[0097]
In addition, since the drain pipe 117 is inserted between the cooling water pump 100 and the lubricating oil pump 101 of the housing unit 103, and the drain pipe 117 is communicated outward, water leaking from the cooling water pump 100 can be drained. In addition, it is possible to reliably prevent water from being mixed into the lubricating oil while disposing the cooling water pump 100 in the crankcase.
[0098]
According to the starting device of the present embodiment, the output gear 136 of the starting motor 135 is meshed with the starting gear 139 mounted on the main shaft 72 via the intermediate gears 138a and 138b, and meshed with the starting gear 139 and the crankshaft 21. Since the one-way clutch 140 is interposed between the large reduction gear 83 and the starting gear 139, the intermediate gears 138a and 138b, and the output gear 136 do not rotate after the engine is started, the loss horsepower can be reduced.
[0099]
In addition, since the starting gear 139 and the one-way clutch 140 are arranged between the large reduction gear 83 of the main shaft 72 and the input gear group 71, they can be arranged compactly by effectively utilizing the axial dead space of the main shaft 72. Further, the crankshaft can be made shorter than one in which the one-way clutch is provided on the crankshaft. The axial length and the position of the main shaft 72 are determined by the vehicle width direction position of the reduction small gear 82 disposed at the end of the crankshaft 21, the vehicle width direction position of the drive sprocket 79 for the rear wheel 13, and the speed change. The dead space is inevitably determined by the number of stages and the like, so that in the case of an engine having the same specifications as in the present embodiment, the dead space often occurs in the clutch shaft inner portion of the main shaft 72.
[0100]
Since the intermediate shafts 137 of the intermediate gears 138a and 138b are arranged in the axial projection plane of the large reduction gear 83, the layout of the starting device can be made compact and the size of the engine can be reduced. Also, interference with the connecting rod of the starting gear 139 can be avoided while reducing the pitch between the crankshaft and the main shaft.
[0101]
According to the intake device of the present embodiment, the throttle opening sensor 155 is disposed at the end of the carburetor unit 151 on the side of the chain arrangement chamber 43, the throttle pulley is disposed between the first and second carburetors, and the vehicle center line is provided. Since the dimension W1 from L to the outer end of the opening sensor 155 and the dimension W2 from the vehicle body center line L to the outer end of the carburetor unit 151 on the opposite side of the opening sensor 155 are arranged to be substantially the same. The throttle opening sensor 155 can be arranged in an empty space at the end of the chain arrangement chamber 43 side, and the axes X1 to X4 of the carburetors 151a to 151d and the cylinders of the cylinders can be arranged without increasing the vehicle width dimension of the main frame 3. The total amount of offset with respect to the axes Y1 to Y4 can be minimized. As a result, it is possible to reduce the intake passage resistance while reducing the vehicle width to improve the riding position.
[0102]
Further, since the throttle pulley 156 is disposed on the connecting member 154 between the first and second carburetors 151a and 151b located on the side of the chain arrangement chamber 43, the offset between the carburetor and the cylinder can be avoided while avoiding an increase in the width of the vehicle body. The total amount can be minimized and the tuning accuracy of each vaporizer can be improved. That is, for example, when a pulley is arranged at the left end of the carburetor unit, it is necessary to increase the offset amount between the third and fourth cylinders and the carburetor in order to avoid an increase in the width of the vehicle body. Tuning accuracy of the vaporizer is reduced.
[Brief description of the drawings]
FIG. 1 is a left side view of a motorcycle equipped with an engine unit according to an embodiment of the present invention.
FIG. 2 is a right side view of the engine unit.
FIG. 3 is a right side view showing a structure around a chain arrangement chamber of the engine unit.
FIG. 4 is a sectional rear view of the engine unit.
FIG. 5 is a sectional view showing a communication hole portion of the engine unit.
FIG. 6 is a plan view of a cylinder head of the engine unit.
7 is a sectional view of the cylinder head (a sectional view taken along line VII-VII in FIG. 6).
8 is a sectional view of the cylinder head (a sectional view taken along line VIII-VIII in FIG. 6).
9 is a cross-sectional view (a cross-sectional view taken along line IX-IX in FIG. 8) of a fastening portion of the cylinder head.
FIG. 10 is a plan view of an intake camshaft of the engine unit.
FIG. 11 is a left side view of an upper case portion of the engine unit.
FIG. 12 is a sectional view of a transmission of the engine unit.
FIG. 13 is a sectional view of a cooling water pump and a lubricating oil pump of the engine unit.
FIG. 14 is a side view of a lubricating oil pump portion of the engine unit.
FIG. 15 is a developed rear view of the starting device of the engine unit.
FIG. 16 is a schematic plan view of an intake device of the engine unit.
FIG. 17 is a schematic configuration diagram of the intake device.
[Explanation of symbols]
15 Engine unit
21 crankshaft
25 Unit case (crankcase)
26a Assembly opening
26c bottom wall
70 Transmission
71b Sliding groove
72 Main axis (input axis)
74 Drive shaft (output shaft)
90 shift drum
90a Guide groove
91 Input side fork shaft
92 Output side fork shaft
93 Input side shift fork
93a Engagement pin
94 Output side shift fork
96 oil breather room
97 Stopper

Claims (3)

The crankshaft and the output shaft of the transmission are disposed on the plane of the crankcase, and the input shaft of the transmission is disposed away from the plane of the crankcase, and the shift drum is parallel to the input shaft and the output shaft. A vehicle engine in which an input-side fork shaft that supports an input-side shift fork and an output-side fork shaft that supports an output-side shift fork are arranged to face outward from an assembly opening formed in a side surface of the crankcase. In the transmission of the unit, rotation of the input-side shift fork when the input-side shift fork is rotated around the input shaft by engaging with a sliding groove of an input gear mounted on the input shaft. A transmission for an engine unit for a vehicle, wherein a stopper portion for regulating an angle is formed on a side of the crankcase opposite to the input shaft with respect to the input shaft. 2. The vehicle according to claim 1, wherein the stopper restricts the rotation angle of the input-side shift fork to an angle at which an engagement pin of the shift fork is disengaged from a guide groove of a shift drum at a normal position. Transmission of engine unit for vehicle. 3. The transmission according to claim 1, wherein the stopper is formed by a bottom wall of an oil breather chamber formed in the crankcase.

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