CN102168628B - Crankcase structure - Google Patents

Abstract

The invention provides a kind of crankcase structure, it suppresses internal-combustion engine because of the variation of the pasta in the oil sump that causes that tilts and decline, and makes oil return rapidly to prevent inlet port from exposing, thus prevents from producing air pocket in oil pump.Have in the crankcase (2) of the internal-combustion engine (1) of oil sump (61) in bottom at supporting crankshaft (3) and speed changer (4), the inlet port (66) of the oil sucked in oil sump (61) by oil pump (62) is arranged on the bottom of oil sump (61), this crankcase (2) comprising: arrange and make the oil of lubrication bent axle (3) or speed changer (4) turn back to the return opening (74) of oil sump (61), and the next door (71L separated between bent axle (3) and oil sump (61), next door (72L 71R) or between separation speed changer (4) and oil sump (61), 72R), and to be connected with described next door and the internal-combustion engine being configured in the appropriate oil stored by described oil sump at least partially stops time the oil extraction portion (78 on top of pasta, 78 ').

Description

Crankcase structure

Technical field

The present invention relates to a kind of crankcase structure of internal-combustion engine, this crankcase is configured to be provided with oil sump below crankcase, and the bottom of oil sump is provided with inlet port.

Background technique

The internal-combustion engine being provided with oil sump below crankcase comprises lubrication system, and this lubrication system is drawn the oil that is stored in oil sump and is supplied to the lubricant housings needing lubrication.Utilizing in the oily drawing mechanism of oil pump in this lubrication system, is arranged inlet port close to the bottom surface of oil sump, in order to not by the impact of the oil mass be stored in oil sump, makes inlet port immerse completely in oil all the time, avoids sucking air.

If sucked air, then output oil pressure change because of air pocket (エ ア Nogami body) of oil pump, thus oil supply can not be supplied with stable oil pressure to lubricant housings.

Therefore, not only make inlet port close to the bottom surface of oil sump, and, particularly in the internal-combustion engine being installed on two-wheeled vehicle such as grade, even if store internal-combustion engine with tilting of car body in oil sump, the oil of the abundance that inlet port also can not expose from pasta.But, acutely to shake along with car body or when accelerating, slowing down, the pasta in oil sump can change, if variation is large, even then inlet port moment also may expose at internal-combustion engine.Therefore, in order to prevent this situation, just need to store a large amount of oil.

Therefore, there are the following problems: weight can increase, and if oil is spilled over to crankshaft room, because the crank arm of bent axle immerses in oil, therefore, the rotation rubbed along with bent axle can increase.

So, such as, described in following patent documentation 1, proposing by substantially horizontally forming next door in oil sump, controlling the technological scheme of the pasta variation stored in oil sump.

Patent documentation 1:(Japan) JP 2008-223880 publication (Fig. 4)

Internal-combustion engine described in above-mentioned patent documentation 1 is mounted in the two-wheeled internal-combustion engine waiting vehicle, is in the crankcase of collecting bent axle, is provided with the single-cylinder four-stroke internal-combustion engine of speed changer, the below of crankcase is provided with oil sump at the rear of bent axle.

In addition, be formed with respectively to the inner side extension of oil sump the lower alar septum separated up and down from the case periphery wall before and after crankcase.Further, above the lower alar septum of the front side of crankcase, the upper alar septum of the rotating locus convex curvature downwards along crank arm is formed.By these lower alar septum and upper alar septum, the variation of the pasta be stored in oil sump can be suppressed.

The At The Height that the lower alar septum of front and back is roughly the same in the bottom surface apart from oil sump extends to direction close to each other, and between both extension front ends, form the large opening portion being communicated with upper and lower space.

Insert fuel sucking pipe at this opening portion, the inlet port close with the bottom surface of oil sump is set in the lower end of this fuel sucking pipe.

Upper alar septum below bent axle is erected between a pair vertical wall of axle supporting crankshaft, between the case periphery wall of front side, have gap part, and the lowest part bent downwards at the ratio of the midway of rotating locus is formed with outlet mouth slightly by rear.

Therefore, the oil be trapped in above alar septum flows out from outlet mouth to the opening portion just in time between the lower alar septum of front and back, thus reduces the friction that the crank arm rotated immerses the bent axle produced in oil.

But, in above-mentioned patent documentation 1, when internal-combustion engine significantly tilts, particularly when internal-combustion engine all around to tilt along with car body or accelerate, slow down, because the pasta in oil sump can tilt at this moment, therefore, oil easily move by the top of lower alar septum forwards, backwards and the top in next door, top, cause the pasta of oil sump significantly to decline, thus likely make inlet port expose.Further, to move to due to the temporary transient inclination of pasta on next door or returning of oil outside oil sump between crankcase and crankcase cover etc. can be delayed.On the other hand, in order to prevent inlet port from exposing, just needing mass storage oil, thus producing following problem: weight increases, and if oil is spilled over to crankshaft room, then the friction produced along with the rotation of bent axle increases.

In addition, outlet mouth due to upper alar septum is positioned at higher position, and the oil on upper alar septum is along with the rotation of crank arm, extrude from outlet mouth and flow out, and the opening portion between lower alar septum before and after falling into, therefore, easily produce foam, the possibility that foam is sucked by the inlet port be positioned at below this opening portion is very high, further, due to air pocket, the output oil pressure of oil pump easily becomes unstable.

Particularly, in order to adopt metal bearing on bent axle, need to specify above supply oil pressure, if by making oil pump maximize to improve supply oil pressure, then cause internal-combustion engine to become maximization.

Summary of the invention

The present invention makes to solve the problem, its object is to the crankcase structure that a kind of internal-combustion engine is provided, its can suppress gasoline engine vibration, tilt time oil sump in pasta variation, pasta is suppressed to decline, and make the oil of the movement due to inclination promptly return oil sump to expose to prevent inlet port, in addition suppress the oil returning oil sump to bubble, can prevent from producing cavitation erosion at oil pump.

In order to achieve the above object, first aspect of the invention provides a kind of crankcase structure, have in the crankcase of the internal-combustion engine of oil sump in bottom at supporting crankshaft and speed changer, the inlet port of the oil sucked in described oil sump by oil pump is arranged on the bottom of this oil sump, the feature of this crankcase structure is, comprise: next door, its setting makes the oil of the described bent axle of lubrication or described speed changer turn back to the return opening of described oil sump, and separates between described bent axle and described oil sump or between described speed changer and described oil sump; Oil extraction portion, its be connected with described next door and the internal-combustion engine being configured in the appropriate oil stored by described oil sump at least partially stops time the top of pasta.

On the basis of the crankcase structure that second aspect of the invention is recorded in first aspect of the invention, have pedal axle be bearing in by described crankcase be arranged on outside this crankcase first hood-shaped become the first side room in pedal starting structure; From pedal axle direction, described oil extraction portion is configured in the position overlapping with the foot-operated actuation gear of described pedal starting structure.

On the basis of the crankcase structure that third aspect of the invention is recorded in first aspect or second aspect of the invention, be installed on by described internal-combustion engine under the state on vehicle, the transmission shaft of described bent axle and described speed changer is configured to the overall width direction pointing to this vehicle; Described crankcase structure comprises: a pair vertical wall, and it is made up of the first vertical wall and the second vertical wall that can support described bent axle and described transmission shaft rotatably; Case periphery wall, this pair vertical wall connects by it; Described oil extraction portion to be connected between described a pair vertical wall and to be connected on described case periphery wall.

On the basis of the crankcase structure that fourth aspect of the invention is recorded in third aspect of the invention, comprise: spill port, it forms the opening being formed in described first vertical wall along the upper limb in described oil extraction portion, and make the oil of this oil extraction portion periphery to by described first vertical wall be arranged on outside this first vertical wall first hood-shaped become the first side room in discharge; Oil sump intercommunicating pore, in the below in described next door, it forms the opening being formed in described first vertical wall, and the oil in described first side room is turned back to described oil sump.

On the basis of the crankcase structure that fifth aspect of the invention is recorded in the third aspect or fourth aspect of the invention, described oil extraction portion is configured in the below of the speed change gear of described speed changer, and the axially extended top wall had to described transmission shaft, this top wall tilts downwards from described case periphery wall towards described spill port.

On the basis of the crankcase structure that sixth aspect of the invention is recorded in fourth aspect of the invention, the foot-operated actuation gear being bearing in the pedal axle of pedal starting structure and the foot-operated driven gear being bearing in described transmission shaft are engaged with each other via described spill port.

On the basis of the crankcase structure that seventh aspect of the invention is recorded in fourth aspect of the invention, described first cover has cooling fin.

On the basis of the crankcase structure that eighth aspect of the invention is recorded in fifth aspect of the invention, described crankcase is the split casting housing be made up of with second crankcase with described second vertical wall first crankcase with described first vertical wall, described first crankcase from described first vertical wall each other to equidirectional extend described case periphery wall, next door, top wall and described second crankcase from described second vertical wall each other to the described case periphery wall that equidirectional extends, next door, top wall engages on mating face, described oil extraction portion is by by described first crankcase and the second crankcase described case periphery wall separately, the hollow space that next door and top wall engage on mating face and close is formed.

Ninth aspect of the invention provides a kind of crankcase structure, have in the crankcase of the internal-combustion engine of oil sump in bottom at supporting crankshaft and speed changer, the inlet port of the oil sucked in described oil sump by oil pump is arranged on the bottom of this oil sump, the feature of this crankcase structure is, comprise: next door, its setting makes the oil of the described bent axle of lubrication or described speed changer turn back to the return opening of described oil sump, and separates between described bent axle and described oil sump or between described speed changer and described oil sump; Oil extraction portion, it is not directly connected with described next door and is shaped in described crankcase, and the top of pasta when the internal-combustion engine being configured in the appropriate oil stored by described oil sump at least partially stops.

According to the crankcase structure of first aspect of the invention, when gasoline engine vibration, inclination, even if the oil of oil sump exceedes next door because of the variation of pasta, because oil extraction portion is submerged in oil, therefore, the pasta in oil sump also can be suppressed to decline, make pasta maintain eminence to prevent exposing of inlet port, thus can prevent from producing air pocket in oil pump, oil pressure can be suppressed to change.Therefore, by stablizing and specifying above supply oil pressure, the application of metal bearing on bent axle becomes more suitable.

According to second aspect of the invention, on the basis of the effect of first aspect of the invention, along pedal axle to seeing, because oil extraction portion is configured in the position overlapping with the foot-operated actuation gear of pedal starting structure, therefore, the miniaturization of internal-combustion engine becomes possibility.

According to third aspect of the invention, on the basis of the effect of first aspect or second aspect of the invention, owing to utilizing vertical wall, case periphery wall and next door to form oil extraction portion, therefore, it is possible to suppress the weight of crankcase to increase.In addition, owing to internal-combustion engine to be arranged on overall width direction vehicle pointing to vehicle with the bent axle and transmission shaft that make crankcase, therefore, next door is separated between bent axle and oil sump, or between speed changer and oil sump, particularly vehicle fore-and-aft direction vibration and tilt in large vehicle, effectively can realize the effect of first aspect of the invention.

According to fourth aspect of the invention, on the basis of the effect of third aspect of the invention, after the oil in oil extraction portion being discharged temporarily to the first side room in crankcase via spill port, to turn back to the oil sump in crankcase via oil sump intercommunicating pore from the lower below next door, therefore, the foaming in oil sump can be reduced, more effectively can prevent from producing cavitation erosion at oil pump, oil pressure can be suppressed to change.

According to fifth aspect of the invention, on the basis of the effect of the third aspect or fourth aspect of the invention, by top wall is configured in higher position in order to avoid produce with speed change gear and disturb, the maximization in oil extraction portion becomes possibility, further, because the oil in top wall successfully can turn back to oil sump from spill port, therefore, the oil that oil capacity but can be guaranteed in oil sump can not be increased, realize the miniaturization of internal-combustion engine, lightweight.

According to sixth aspect of the invention, on the basis of the effect of fourth aspect of the invention, foot-operated actuation gear and foot-operated driven gear can be lubricated well.

According to seventh aspect of the invention, on the basis of the effect of fourth aspect of the invention, owing to being promoted the cooling of the first cover covering the first side room that oil flows from spill port to oil sump intercommunicating pore by cooling fin, therefore, facilitate the cooling of the oil in oil sump.

According to eighth aspect of the invention, on the basis of the effect of fifth aspect of the invention, by the hollow space that oil extraction portion is designed to close, the rigidity of crankcase can be guaranteed and seek lightweight.In addition, by case periphery wall, next door and top wall are extended in the same direction and are formed, when casting the crankcase as split housing, on the first crankcase and the second crankcase, the halfbody in oil extraction portion can be formed respectively, thus oil extraction portion can be formed when not increasing machining period.

According to ninth aspect of the invention, when gasoline engine vibration, inclination, even if the oil of oil sump exceedes next door because of the variation of pasta, because oil extraction portion is submerged in oil, therefore, the pasta in oil sump also can be suppressed to decline, make pasta maintain eminence to prevent exposing of inlet port, thus can prevent from producing air pocket in oil pump, oil pressure can be suppressed to change.Therefore, by stablizing and specifying above supply oil pressure, the application of metal bearing on bent axle becomes more suitable.In addition, because oil extraction portion is formed as the enclosed space that is not directly connected with next door, therefore, it is possible to the weight controlling crankcase increases.

Accompanying drawing explanation

Fig. 1 be the two-wheeled internal-combustion engine of first embodiment of the invention omission right crankcase and from the right side pseudosection of left crankcase viewed from inner side.

Fig. 2 is the II-II profile stretch-out view of Fig. 1, and Fig. 1 is equivalent to the I-I of Fig. 2 to pseudosection.

Fig. 3 is the right side elevational schematic view of III-III to the first mode of execution looked of Fig. 2, is the position description figure of the inlet port of omissions of detail, oil pump etc.

Fig. 4 omits the IV-IV of the Fig. 2 representing left crankcase to left side (inner side) view of the right crankcase looked, and eliminates each axle of installation etc. and only shows their shaft core position.

Fig. 5 is the V-V that omits the Fig. 2 representing right crankcase cover right side (outside) view to the right crankcase looked, and eliminates each axle of installation etc. and only shows their shaft core position.

Fig. 6 is the sectional arrangement drawing of VI-VI to the right crankcase looked of Fig. 4 (and Fig. 6).

Fig. 7 is the partial longitudinal section of VII-VII to the left crankcase looked of Fig. 1.

Fig. 8 (a) be Fig. 2 VIIIa-VIIIa to depending on the right External view seeing right crankcase cover from right side (outside), (b) is that the VIIIb-VIIIb of (a) is to the sectional arrangement drawing looked.

Fig. 9 is with the omission right crankcase of the crankcase of the first mode of execution first variation of Fig. 1 equidirectional and from the right side elevational cross-section Local map of left crankcase viewed from inner side.

Figure 10 is with the omission right crankcase of the crankcase of the first mode of execution second variation of Fig. 1 equidirectional and from the right side elevational cross-section Local map of left crankcase viewed from inner side.

Figure 11 is with the omission right crankcase of the crankcase of the first mode of execution the 3rd variation of Fig. 1 equidirectional and from the right side elevational cross-section Local map of left crankcase viewed from inner side.

Figure 12 is with the omission right crankcase of the two-wheeled internal-combustion engine of the second embodiment of the invention of Fig. 1 equidirectional and from the right side pseudosection of left crankcase viewed from inner side.

The explanation of reference character

1 internal-combustion engine; 2 crankcases; 2L left crankcase (the second crankcase); 2R right crankcase (the first crankcase); 3 bent axles; 4 speed changers; 5 cylinder part; 6AC generator; 7 multi-disc friction clutches; 8 pedal starting structures; 10 pistons; 11 connecting rods; 12 firing chambers; 13 suction ports; 14 relief openings; 15 suction valves; 16 outlet valves; Space in 20 casees; The left vertical wall of 21L (the second vertical wall); The right vertical wall of 21R (the first vertical wall); The left case periphery wall of 22L (case periphery wall); The right case periphery wall of 22R (case periphery wall); 23 crankshaft room; 24 speed changer rooms; 25L left crankcase cover; 25R right crankcase cover (the first cover); Room on the left of 26L; On the right side of 26R room (the first side room); 27L mating face; 27R mating face; 28R right ring-type frame wall; 29R mating face; 30L crank arm; 30R crank arm; 31 crank pins; The left metal bearing of 32L; The right metal bearing of 32R; 33 cam chain driving sprocket wheels; 34 main actuation gears; 40 main shafts (transmission shaft); 41 countershafts (transmission shaft); 42L left bearing; 42R right bearing; 43L left bearing; 43R right bearing; 44 gear train; 45 driven tooth trains (speed change gear); 46 main driven gears; 47 output sprockets; 48 rear wheel drive chains; 49 foot-operated driven gears; 50 cylinder block; 51 cylinder head; 55 speed transmission drums; 56a selector fork; 57 balancer weights; 58 trunnion shafves; 60 openings (spill port); 61 oil sumps; 62 oil pumps; 63L oil suction path upper left wall; 63R oil suction path upper right wall; 64 oil suction paths; The left back wall of 65L oil suction path; The right back wall of 65R oil suction path; 66 inlet ports; 67 rectangular openings; 68 oily fuel filters; 69 oily access; 70 oil rectifiers; 71L front left side next door (next door); 71R forward right side next door (next door); 72L left rear side next door (next door); 72R right lateral side next door (next door); 73L upper left quarter wall (top wall); 73R upper right quarter wall (top wall); 74 return openings; 75 forward right side spill ports (spill port); 76 oil sump intercommunicating pores; 77 front left side spill ports; 78 oil extraction portions; 78 ' oil extraction portion, front side (oil extraction portion); 80 pedal axles; 81 left parts; 82a left bearing portion; 82b right bearing portion; 83 right sides; 84 pedals; 85 foot-operated actuation gears; Wall is protruded in 87 ventilations; 88 ventilation chamber diapires; 89 ventilation chamber; 90 cooling fin; 91 ditch portions; 100 power units; 172L left rear side next door (next door); 173L upper left quarter wall (top wall); 178 oil extraction portions; 272L left rear side next door (next door); 273L upper left quarter wall (top wall); 278 oil extraction portions; 371L front left side next door (next door); On front side of in the of 378 oil extraction portion (oil extraction portion); The left back midfeather of 473aL; The left back top wall of 473bL; 478 oil extraction portions.

Embodiment

Below, based on Fig. 1 ~ Figure 11, the crankcase structure of first embodiment of the invention is described.

In this specification and claims book, all around go up inferior direction with at the two-wheeled vehicle waited under the state that the internal-combustion engine of present embodiment installed by vehicle towards consistent.In figure, arrow FR represents vehicle front, and LH represents vehicle left, and RH represents vehicle right, and UP represents vehicle up direction.

Further, the small arrow device, structural portion of each figure marked schematically shows the flow direction of lubrication oil.

The internal-combustion engine 1 of present embodiment is single-cylinder four-stroke internal-combustion engine, and on not shown vehicle is such as two-wheeled, the axle of the bent axle 3 and speed changer 4 that this internal-combustion engine 1 are configured to crankcase 2 points to the overall width direction of vehicle.

Fig. 1 represents the attitude be arranged on by the internal combustion engine for vehicle 1 of present embodiment on not shown vehicle.

As shown in Figure 1, internal-combustion engine 1 has the following cylinder part 5 formed: under the state that internal-combustion engine is installed on vehicle, the axis Y of bent axle 3 is orthogonal with the fore-and-aft direction of vehicle and point to width of the carbody direction, the rotatable earth's axis of bent axle 3 is bearing in crankcase 2, further, this cylinder part 5 is given prominence to upward from crankcase 2 and cylinder axis X opposed vertical line is leaned forward.Cylinder part 5 is configured to: in the oblique upper of crankcase 2, and overlap also connects cylinder block 50 and cylinder head 51 integratedly in order, and cylinder head 51 covers not shown valve mechanism cover.

Piston 10 is inlaid in the cylinder block 50 of giving prominence to obliquely upward from crankcase 2 slidably, and is connected with the crank handle between crank arm 30L, 30R of being erected at bent axle 3 via connecting rod 11.According to the action of piston 10, make bent axle 3 rotary actuation (with reference to Fig. 2).

In the bottom of cylinder head 51, the top of piston 10 is formed with firing chamber 12.Firing chamber 12 is connected with suction port 13, relief opening 14, is provided with the suction valve 15 and the outlet valve 16 that the inner of suction port 13 and relief opening 14 are carried out to opening and closing in firing chamber 12.

Suction port 13 is connected with not shown throttle-valve body and Fuelinjection nozzle.

As shown in the II-II profile stretch-out view of Fig. 1 and Fig. 2, the cast housing that the crankcase 2 of internal-combustion engine 1 is split by left and right is formed, between left crankcase 2L (" the second crankcase " of the present invention) and right crankcase 2R (" the first crankcase " of the present invention), be formed with space 20 in case.

In case, space 20 is between left vertical wall 21L respect to one another (" the second vertical wall " of the present invention), right vertical wall (" the first vertical wall " of the present invention), the space formed is surrounded by left and right case periphery wall 22L, 22R (" case periphery wall " of the present invention), in this case, space 20 is that crankshaft room 23 is positioned at front and back and the space be communicated with mutually with speed changer room 24, wherein, the crank arm 30L of the counterweight forming bent axle 3 accommodates in crankshaft room 23,30R, the speed changer 4 forming normal mesh gear gear is accommodated in speed changer room 24.

Left crankcase cover 25L and right crankcase cover 25R (" the first cover " of the present invention) covers the outside of the left and right directions of left crankcase 2L and right crankcase 2R.

Between left crankcase 2L and left crankcase cover 25L, be formed with room, the left side 26L of collecting AC generator 6, between right crankcase 2R and right crankcase cover 25R, be formed with room, the right side 26R (" the first side room " of the present invention) of collecting multi-disc friction clutch 7, pedal starting structure 8.

The lateral part root of bent axle wall 30L, 30R of bent axle 3 is bearing on left and right vertical wall 21L, 21R relative to each other of left crankcase 2L and right crankcase 2R via the left and right rotatable earth's axis of metal bearing 32L, 32R.When adopting metal bearing, needing the stable of lubricant oil and specifying above supply oil pressure.

In the 26L of room, left side from the bent axle 3 that this left metal bearing 32L gives prominence to the left, the cam chain driving sprocket wheel 33 of active valve mechanism is installed, and left end side is provided with AC generator 6, AC generator 6 is covered by left crankcase cover 25L.

As shown in Figure 2, at crankcase 2L to the left and right, the left and right vertical wall 21L of 2R, between two vertical walls of the rear extension of 21R, with the axis Y of bent axle 3 abreast, via left and right bearing 42L, 42R is rotatably supported by the shaft with the main shaft 40 (" transmission shaft " of the present invention) of speed changer 4, via left and right bearing 43L, 43R is rotatably supported by the shaft with the countershaft 41 (" transmission shaft " of the present invention) of speed changer 4, and, the gear train 44 being bearing in main shaft 40 and the driven tooth train 45 (" speed change gear " of the present invention) being bearing in countershaft 41 engage the gear of each correspondence all the time, and be housed in speed changer room 24.

In the right side of the main shaft 40 by through to the right for right vertical wall 21R and outstanding in the 26R of side room speed changer 4, be assembled with the multi-disc friction clutch 7 of gearshift as described above to the right.

Although the rotating power of bent axle 3 is passed to multi-disc friction clutch 7 via the main actuation gear 34 of bent axle 3 side, the main driven gear 46 of multi-disc friction clutch 7 side, but, multi-disc friction clutch 7 is configured to: in the gear of speed changer 4 switches, the rotating power of bent axle 3 is not transmitted to speed changer 4, be in neutral position state, while the gear finishing switching of speed changer 4, the rotating power of bent axle 3 is transmitted to speed changer 4.

In the left part by through to the left for left vertical wall 21L and externally outstanding countershaft 41, be embedded with output sprocket 47, output sprocket 47 has been wrapping with rear wheel drive chain 48.

That is, its crankcase 2 is formed so-called power unit 100 as power unit case by the internal-combustion engine 1 of present embodiment, and countershaft 41 becomes the output shaft of power unit 100.

In speed changer room 24, be entrenched on the countershaft 41 close with right bearing 43R by the foot-operated driven gear 49 that pedal starting structure 8 drives.

In the 26R of room, right side, the left part 81 of the pedal axle 80 of pedal starting structure 8 is bearing on the left bearing portion 82a on the right side (outside) of the right vertical wall 21R being arranged at right crankcase 2R, right part 83 is bearing on right crankcase cover 25R via right bearing portion 82b, and through right crankcase cover 25R, and pedal 84 is installed.

Adjacent with left part 81 and chimericly have the foot-operated actuation gear 85 engaged with foot-operated driven gear 49 on pedal axle 80, foot-operated driven gear 49 and foot-operated actuation gear 85 are separately positioned at the inner side and outer side of right vertical wall 21R, engage each other via the opening 60 (" spill port 60 " described later) being arranged on right vertical wall 21R.

As shown in Figure 2, main shaft 40 is parallel with bent axle 3 with countershaft 41, and as shown in Figure 1, main shaft 41 is positioned at the oblique upper at the rear of bent axle 3, and countershaft 41 is positioned at the oblique below at the more rear of main shaft 40.

Main shaft 40 roughly immediately below, the position lower than countershaft 41 is configured with speed transmission drum 55.Speed transmission drum 55 is rotated by not shown Shift spindle (シ Off ト ス ピ Application De Le), select each meshed gears centering of the gear train 44 of speed changer 4 and driven tooth train 45 gear mesh effectively carrying out transmission of power to make selector fork 56a, 56b move, carry out speed change thus.

Further, in the front of bent axle 3, the trunnion shaft 58 with balancer weight 57 is rotatably erected on left and right vertical wall 21L, 21R, and via not shown gear by bent axle 3 rotary actuation.

And, as shown in Figure 1, in crankcase 2, left and right case periphery wall 22L, the 22R of left and right crankcase 2L, 2R above speed changer room 24 form ventilation and protrude wall 87 across left and right crankcase 2L, 2R protrude upward, the inside that wall 87 is protruded in ventilation is separated by ventilation chamber diapire and speed changer room 24, thus forms ventilation chamber 89.

Fig. 1 omits right crankcase 2R and right side (inner face) view of internal-combustion engine 1 from the part section of left crankcase 2L viewed from inner side, and the mating face 27L (shown in trellis shade part) of left crankcase 2L and right crankcase 2R is formed ring-type (having cut locally cylinder part).

On the other hand, Fig. 4 omits left crankcase 2L and left side (inner face) view of right crankcase 2R from right crankcase 2R viewed from inner side, and the mating face 27R (shown in trellis shade part) of right crankcase 2R and left crankcase 2L is formed ring-type (having cut locally cylinder part).

Therefore, the mating face 27R of the right crankcase 2R shown in mating face 27L and Fig. 4 of the left crankcase 2L shown in Fig. 1 is docked, form space 20 in case that inside as shown in Figure 2 has crankshaft room 23 and a speed changer room 24.

In addition, Fig. 5 is that (outside) figure is looked on the right side after the right crankcase cover 25R pulling down right crankcase 2R, to be provided with together with right vertical wall 21R side to the right at right crankcase 2R and to give prominence to the right ring-type frame wall 28R of formation, and be formed with the annular engaging surface 29R (part shown in trellis shade) of itself and right crankcase cover 25R in its its right end face.

Right crankcase cover 25R is docked at the mating face 29R of the right ring-type frame wall 28R of right crankcase 2R, and covers the right side of right crankcase 2R, thus is formed with right side room 26R therein.

As shown in Figure 1 and Figure 4, left and right case periphery wall 22L, 22R of left and right crankcase 2L, 2R cover periphery in the following manner: rearward bend extension from the front of trunnion shaft 58 through the below of the below of bent axle 3 and speed changer 4, and the bending extension upward through the rear of speed changer 4, thus arrive the top of speed changer 4.

The inner side end of left and right case periphery wall 22L, 22R is each mating face 27L, 27R.

In left and right crankcase 2L, 2R, left and right vertical wall 21L, 21R and left and right case periphery wall 22L, 22R extend downwards and form the oil sump 61 of the oil in reserve of depression in the below of crankshaft room 23 and speed changer room 24.

All the time be necessary to store appropriate oil in oil sump 61, in Fig. 1 and Fig. 4, represent the appropriate average pasta S of oil when internal-combustion engine stops (below, in this manual referred to as " during stopping pasta S ") with double dot dash line.

When internal-combustion engine 1 stops, if when pasta is positioned at this stopping pasta S upper and lower near, then oil is appropriate.

If internal-combustion engine 1 works, then the oil in oil sump 61 is drawn by the driving of oil pump 62 (with reference to Fig. 3), is supplied to each lubricant housings, and therefore, pasta during work is in the position lower than pasta S during stopping shown in Fig. 1 and Fig. 4 always.

As shown in Figure 4, at the inner face of right crankcase 2R, above the front half part of the bottom surface of oil sump 61, be rearward connected integratedly with right vertical wall 21R from the front panel of right case periphery wall 22R and extend and be formed with oil suction path upper right wall 63R along bottom surface.

Oil suction path upper right wall 63R abuts with the oil suction path upper left wall 63L (with reference to Fig. 1) being formed in left crankcase 2L symmetrically and between the bottom surface of oil sump 61, is formed with oil suction path 64.

Now, the left and right of the flattened rectangular opening formed between the rear end of oil suction path left and right upper wall 63L, 63R and the bottom surface of oil sump 61 is closed by oil suction path left and right rear wall 65L, 65R, and forms inlet port 66 (with reference to Fig. 6) in central authorities.

The right flank (outside) of the right vertical wall 21R of the right crankcase 2R shown in Fig. 5, be formed by right ring-type frame wall 28R with flattened rectangular perforation rectangular opening 67, at rectangular opening 67, oily fuel filter 68 is installed.

The below of rectangular opening 67 is communicated with oil suction path 64 via oily access 69 (with reference to Fig. 4).This oily access 69 is bored a hole at right vertical wall 21R along the lower edge of oil suction path upper right wall 63R.

The right crankcase cover 25R that the right-end openings of rectangular opening 67 is installed by being blocked by the right flank of right crankcase 2R closes, and the top of rectangular opening 67 is communicated with the oil pump 62 be arranged between the right vertical wall 21R of right crankcase 2R and the inner face of right crankcase cover 25R.

Therefore, as shown in Figure 3, if internal-combustion engine 1 works and drives oil pump 62, oil near the bottom surface of the oil sump 61 then in crankcase 2 flows into oil suction path 64 from inlet port 66, and suck in rectangular opening 67 via oily access 69, and be filtered by the oily fuel filter 68 be arranged in rectangular opening 67, thus sucked by oil pump 62.The oil pump 62 of present embodiment is trochoid pump.

Subsequently, to be pressurizeed by oil pump 62 and the oil exported is supplied to each lubricant housings through oil rectifier 70 etc.

In addition, as shown in Figure 1, at the inner face of left crankcase 2L, front left side next door (crankshaft side next door) 71L is to separate the height of the below of crank arm 30L, the 30R of the counterweight with bent axle 3 up and down, from the front panel of left case periphery wall 22L through the below of trunnion shaft 58, and along the outer periphery convex curvature and extending towards the rear downwards of the rotating locus of crank arm 30L, 30R, thus separate between bent axle 3 and oil pump 61.Pasta S when the bottom of front left side next door 71L immerses stopping a little, the top of pasta S when the rear end side at least in its part and present embodiment is positioned at stopping.

In addition, the height of the below of pasta S when left rear side next door (transmission side next door) 72L is to separate stopping up and down, extend from the rear sidewall front left side next door 71L forwards of left case periphery wall 22L, thus separate between speed changer 4 and oil sump 61, and, above the 72L of left rear side next door, upper left quarter wall 73L forwards extends along the driven tooth train 45 of speed changer 4 in below from the rear sidewall of left case periphery wall 22L.

The top of pasta S when the major part of upper left quarter wall 73L is positioned at stopping, and when relatively stopping, pasta S forward downward tilts, and is connected in the forward end of its forward end with left rear side next door 72L.Left case periphery wall 22L, left rear side next door 72L and upper left quarter wall 73L are interconnected to form the closed wall body of general triangular, and top and the mating face 27L of this wall body become the same face.

There is between the connecting part of the front end of left rear side next door 72L and upper left quarter wall 73L and the rear end of front left side next door 71L the interval of regulation, in this compartment, be configured with speed transmission drum 55.

As shown in Figure 4, at the inner face of right crankcase 2R, be formed with forward right side next door 71R, right lateral side next door 72R and upper right quarter wall 73R symmetrically with front left side next door 71L, the left rear side next door 72L of the inner face of left crankcase 2L and upper left quarter wall 73L.

Therefore, if left crankcase 2L and right crankcase 2R is fit, then the mating face that next door, front side, left and right 71L, 71R is formed each other abuts and becomes the next door, front side (" next door " of the present invention) of the one of the same face.

In addition, 72L, 72R mating face formed each other, rear side next door, left and right abuts and becomes the rear side next door (" next door " of the present invention) of the one of the same face, and the mating face that left and right top wall 73L, 73R are formed each other abuts and becomes the top wall (" top wall " of the present invention) of the one of the same face.

Therefore, right case periphery wall 22R, right lateral side next door 72R that the same each other axial left direction from right vertical wall 21R along speed changer 4 of the periphery wall 22L that left crankcase 2L the same each other axial right direction from left vertical wall 21L along speed changer 4 extends, left rear side next door 72L, upper left quarter wall 73L and right crankcase 2R extends, upper left quarter wall 73R engage to form closed space on mating face, thus form oil extraction portion 78.

Therefore, because oil extraction portion 78 has space, therefore, it is possible to guarantee the intensity of crankcase 2, and realize lightweight.

Oil extraction portion 78 is connected with next door 72L, 72R on rear side of left and right, the top of pasta S when the major part at its rear portion is configured in stopping.

Therefore, when internal-combustion engine 1 tilted rearward, even if the oil of oil sump 61 exceedes rear side next door, left and right 72L, 72R because of variations such as pasta rearward move, because oil extraction portion 78 is submerged in oil, therefore, the pasta in oil sump 61 also can be suppressed to decline.In addition, when internal-combustion engine 1 lateral inclination, the part being submerged in the oil extraction portion 78 in oil also obtains identical effect.

Therefore, it is possible to the pasta in oil sump 61 is maintained higher position, thus can prevent inlet port 66 from exposing, can prevent from producing air pocket in oil pump 62, the variation of oil pressure can be suppressed.

In addition, due to the top of pasta S when the rear end side of next door 71L, 71R on front side of left and right is positioned at stopping, therefore, when internal-combustion engine 1 forwards tilts, when the oil of oil sump 61 exceedes front side, left and right next door 72L, 72R because of variations such as pasta forwards move, because rear end side is submerged in oil, therefore, there is the function in the oil extraction portion, front side 78 ' (" oil extraction portion " of the present invention) that the pasta controlled in oil sump 61 declines.When internal-combustion engine 1 lateral inclination, the part being submerged in the oil extraction portion 78 ' in oil also obtains identical effect.

Fig. 9 to Figure 11 represents that the first variation of the crankcase structure of present embodiment is to the 3rd variation.

Each variation illustrates the variation in oil extraction portion 78 or oil extraction portion, front side 78 ', in addition, identical with present embodiment.

In the above-described first embodiment, left case periphery wall 22L, the left rear side next door 72L of left crankcase 2L and upper left quarter wall 73L form closed annular wall, and right crankcase 2R also forms corresponding identical annular wall, thus form the oil extraction portion 78 with enclosed space.On the other hand, in the first variation shown in Fig. 9, in left crankcase 2L, a part of left case periphery wall 22L is excised, the recess that the outside to crankcase 2 opens is formed between left rear side next door 172L (" next door " of the present invention) and upper left quarter wall 173L (" top wall " of the present invention), in right crankcase 2R, form the same structure corresponding with it, thus form oil extraction portion 178.

By this oil extraction portion 178, the effect that prevent pasta from declining identical with above-mentioned first mode of execution can not only be realized, and lightweight, the miniaturization of crankcase 2 can be realized.

In the second variation shown in Figure 10, in left crankcase 2L, make to be formed between left case periphery wall 22L, left rear side next door 272L (" next door " of the present invention) and upper left quarter wall 273L (" top wall " of the present invention) solid integrative-structure by casting etc., in right crankcase 2R, also form the same structure corresponding with it, thus form oil extraction portion 278.

By this oil extraction portion 278, the effect that prevent pasta from declining identical with above-mentioned first mode of execution can not only be realized, and logical excessive use metallic material, the cooling of crankcase 2 can be improved, and reduce the center of gravity of internal-combustion engine 1.

In the 3rd variation shown in Figure 11, in left crankcase 2L, on the basis in the oil extraction portion 78 of above-mentioned first mode of execution, form the bottom of front left side next door 371L (" next door " of the present invention) thickly, in right crankcase 2R, also form same structure corresponding thereto, thus form oil extraction portion 378, front side (" oil extraction portion " of the present invention).

In the first embodiment, the top of pasta S when the rearward end of next door 71L, 71R is positioned at stopping on front side of left and right, on front side of left and right, next door 71L, 71R itself have the certain function as oil extraction portion, front side 78 '.But, owing to constituting the larger oil extraction portion, front side 378 of volume in the 3rd variation, therefore, when internal-combustion engine 1 forwards tilts, even if the oil of oil sump 61 exceedes next door, front side, left and right because of variations such as pasta forwards move, because oil extraction portion, front side 378 is submerged in oil, therefore, the pasta in oil sump 61 also can be suppressed to decline.When internal-combustion engine 1 lateral inclination, the part being submerged in the oil extraction portion, front side 378 in oil plays same effect.

Therefore, it is possible to the pasta in oil sump 61 is maintained higher position, prevent inlet port 66 from exposing, can prevent from producing air pocket in oil pump 62, oil pressure can be suppressed to change.

Above-mentioned first to the 3rd variation is not limited to above-mentioned mode, can be implemented by the mode of possible combination in any, and such as, the 3rd variation can be combined with the second variation or the 3rd variation and implement.

In addition, the oil extraction portion 78 of present embodiment is in left crankcase 2L side, formed in the scope of being surrounded by left case outer circumferential side 22L, left rear side next door 72L and upper left quarter wall 73L and on the whole width of left crankcase 2L (with reference to Fig. 2), but, in right crankcase 2R, as shown in Figure 4, from the direction of pedal axle 80, the pedal axle 80 of aforesaid pedal starting structure 8 is positioned at the region in the oil extraction portion 78 surrounded by right case periphery wall 22R, right lateral side next door 72R and upper right quarter wall 73R in an overlapping manner.

Therefore, be arranged on the back side of the left bearing portion 82a of the pedal axle 80 on the right side (outside) of the right vertical wall 21R of right crankcase 2R, be positioned at the mating face neighbouring (with reference to figure 2) of right crankcase 2R and left crankcase 2L.

In addition, on pedal axle 80, because foot-operated actuation gear 85 is adjacent and chimeric with on the right side of left bearing portion 82a, therefore, from pedal axle 80 direction (viewed from pedal axle direction), oil extraction portion 78 is configured in the position overlapping with the foot-operated actuation gear 85 of pedal starting structure 8, and right vertical wall 21R forms step and left direction evagination in the mode avoiding foot-operated actuation gear 85.

Therefore, the depth as shallow that formed in the direction of the width of the oil extraction portion 78 of right crankcase 2R side.

Step is formed and the shape protruded by the vertical wall 21R left direction around the configuration of above-mentioned pedal axle 80 and foot-operated actuation gear 85, foot-operated driven gear 49 and foot-operated actuation gear 85 are separately positioned at the inner side and outer side of right vertical wall 21R, but, opening 60 via the stepped part being arranged on right vertical wall 21R is engaged with each other, therefore, the crankcase 2 even miniaturization of internal-combustion engine 1 (with reference to Fig. 2) is contributed to.In addition, opening 60 becomes side room 26R to the right and promptly discharges in lubrication speed changer room 24 and wait and the spill port 60 (" spill port " of the present invention) of oil on arrival left and right, below top wall 73L, the 73R of countershaft 41.

Therefore, foot-operated driven gear 49 and foot-operated actuation gear 85 are lubricated well by the oil by spill port 60.

In addition, the joint of front end and the rear end in next door, front side 71 of left and right rear side next door 72L, 72R and left and right top wall 73L, 73R have the interval of regulation and form rectangular aperture, and this rectangular aperture forms the return opening 74 that the oil lubricating bent axle 3 or speed changer 4 turns back to oil sump 61.Return opening 74 is positioned at the top of inlet port 66.In addition, on return opening 74, speed transmission drum 55 is configured in the position (with reference to Fig. 1) of blocking rectangular aperture.Therefore, the oil flowing to oil sump 61 from return opening 74 reduces inflow velocity, influx due to speed transmission drum 55, arrive most of oil on left and right rear side next door 72L, 72R and left and right top wall 73L, 73R from spill port 60 and following forward right side spill port 75 to the right side room 26R discharges, suppress the foaming of the oil generation directly flowed down from the return opening 74 of higher position.

As shown in Figure 4, along the lowermost portion above bending forward right side next door 71R in the right vertical wall 21R of right crankcase 2R, front and back perforation is provided with two forward right side spill ports 75 (drawing some part) downwards.Forward right side spill port 75 (" spill port " of the present invention) is for being communicated with room, the right side 26R (with reference to Fig. 5) in crankshaft room 23 and right crankcase cover 25R.

Further, in right vertical wall 21R, the inferior portion perforation of return opening 74 is provided with oil sump intercommunicating pore 76 (drawing some part).As seen shown in Fig. 5 of right crankcase 2R from outside (right side), oil sump intercommunicating pore 76 (" oil sump intercommunicating pore " of the present invention) along right ring-type frame wall 28R lower portion above formed.

Therefore, waits in lubrication crankshaft room 23 and arrives the oil on front side of left and right on next door 71L, 71R, on the right side of being rapidly to via forward right side spill port 75, room 26R discharges, and above the lower portion flowing down in the 26R of room, right side and arrive ring-type frame wall 28R.

Afterwards, be expelled to right side room 26R from left and right top wall 73L, 73R via spill port 60 in the oil in the room 26R of lubrication right side and aforesaid lubrication speed changer room 24, and all turn back to oil sump 61 from oil sump intercommunicating pore 76 from the oil that room, right side 26R flows out.

Therefore, because the oil of majority flows into oil sump 61 at lower position from the oil sump intercommunicating pore 76 of the side being positioned at inlet port 66, therefore suppress the foaming of oil.

In addition, as shown in Figure 1, in the left vertical wall 21L of left crankcase 2L, the lower side perforation of left front sidewall 71L is provided with front left side spill port 77 (drawing some part).As shown in Figure 7, front left side spill port 77 is communicated with the foot of room, the left side 26L between left crankcase 2L and left crankcase cover 25L, and the oil of AC generator 6 grade in the room 26L of lubrication left side promptly flows into the bottom in crankcase 2, and turns back to oil sump 61.

As mentioned above, in oil in the case that have lubricated crankcase 2 in space 20 (crankshaft room 23, speed changer room 24), most of oil except directly turn back to the oil of oil sump 61 from return opening 74 except, from forward right side spill port 75, spill port 60 to the right side room 26R discharge, and flow down in the 26R of room, right side, turn back to oil sump 61 from oil sump intercommunicating pore 76.

Especially, because the oil of lubrication crankshaft room 23 side is almost all discharged from forward right side spill port 75, therefore, the forward portion of the forward right side spill port 75 of forward right side spill port 75 position close to the right crankcase cover 25R forming room, the right side 26R that oil flows down preferably is made fully to cool, to realize the cooling of oil.

Therefore, as shown in Figure 8, in the crankcase structure of present embodiment, cooling fin 90 is arranged on the front of position corresponding with multi-disc friction clutch 7 in right crankcase cover 25R, i.e. the outside that is close and crankshaft room 23 respective side with the position of forward right side spill port 75.In addition, in the ditch portion 91 that the left direction (interior side direction) being formed in crankcase cover 25R to the right between cooling fin 90 caves in, improve cooling (Air flow) effect of right crankcase cover 25R.

Because the crankcase of this first mode of execution has structure as above, therefore achieve following effect.

Although pasta S when average pasta when internal-combustion engine 1 stops, stopping have been shown in Fig. 1 and Fig. 4, but, in the work of internal-combustion engine 1, oil supplies to each lubricant housings, pasta becomes quite low, such as, lower than next door 72L, 72R on rear side of next door 71L, 71R on front side of left and right and left and right, therefore, even if the oil be stored in oil sump 61 flows along with the swing of internal-combustion engine 1 together with car body, pasta also can be controlled by next door 72L, 72R on rear side of next door 71L, 71R on front side of left and right and left and right, effectively suppresses the flowing of oil.

Especially, when acceleration and deceleration etc. or vehicle tilts forward and back time, when significantly swinging before and after the oil in oil sump 61, by next door 71L, 71R on front side of the left and right that is connected with the front panel inner face of left and right case periphery wall 22L, 22R, oil can be stoped to move in crankshaft room 23 along case periphery, left and right than the front panel inner face backflow of 22L, 22R.And, by next door 72L, 72R on rear side of the left and right that is connected with the rear sidewall inner face of left and right case periphery wall 22L, 22R, oil can be stoped to move in speed changer room 24 along the rear sidewall inner face backflow of left and right case periphery wall 22L, 22R, and then stop in arrival ventilation chamber 89.Therefore, it is possible to suppress oil to increase with the friction of bent axle 3, trunnion shaft 58 and speed changer 4 as much as possible.

Further, controlled the movement of pasta by next door 72L, 72R on rear side of next door 71L, 71R on front side of left and right and left and right, thus the inlet port 66 preventing the bottom surface along oil sump 61 from configuring exposes, and can prevent oil pump 62 from sucking air from inlet port 66 and producing air pocket.

And, the feature of the crankcase structure of present embodiment is, have in the crankcase 2 of the internal-combustion engine 1 of oil sump 61 in bottom at supporting crankshaft 3 and speed changer 4, the inlet port 66 being sucked the oil in oil sump 61 by oil pump 62 is arranged on the bottom of oil sump 61, this crankcase structure comprises: arrange and make the oil of lubrication bent axle 3 or speed changer 4 turn back to the return opening 74 of oil sump 61, and separate next door between bent axle 3 and oil sump 61 (next door 71L on front side of left and right, 71R), or separate next door between speed changer 4 and oil sump 61 (next door 72L on rear side of left and right, 72R), and the oil extraction portion 78 on the top of pasta S when to be connected with each next door and to be configured in stopping at least partially, 78 ', 178, 278, 378.

Therefore, swing at internal-combustion engine 1, when tilting, even if the oil of oil sump 61 exceedes each next door 71L, 71R, 72L, 72R because of the variation of pasta, because oil extraction portion 78,78 ', 178,278,378 is submerged in oil, therefore, it is possible to suppress the pasta in oil sump 61 to decline, thus pasta can be maintained eminence, prevent inlet port 66 from exposing, can prevent from producing air pocket in oil pump 62, oil pressure can be suppressed to change.Therefore, by stablizing and specifying above supply oil pressure, left and right metal bearing 32L, 32R can be made to be useful in well on bent axle 3.

In addition, by crankcase 2 be arranged in room, right side 26R that the right crankcase cover 25R outside crankcase 2 forms, there is the pedal starting structure 8 of supporting pedal axle 80, from pedal axle 80 direction, oil extraction portion 78,178,278 is configured in the position overlapping with the foot-operated actuation gear 85 of pedal starting structure 8.

Therefore, the miniaturization of internal-combustion engine 1 becomes possibility.

In addition, under the state that internal-combustion engine 1 is installed on vehicle, the main shaft 40 of bent axle 3 and speed changer 4, countershaft 41 point to the overall width direction of vehicle and configure.Crankcase 2 is configured to comprise: a pair vertical wall, and it is made up of the right vertical wall 21R of rotatably supporting crankshaft 3 and main shaft 40, countershaft 41 and left vertical wall 21L; Left and right case periphery wall 22L, 22R, it connects vertical wall 21L, 21R of a pair.Oil extraction portion 78,78 ', 178,278,378 is connected with between a pair vertical wall 21L, 21R, and is connected with left and right case periphery wall 22L, 22R.

Therefore, to utilize on front side of left and right vertical wall 21L, 21R, left and right case periphery wall 22L, 22R and left and right next door 72L, 72R on rear side of next door 71L, 71R or left and right to form oil extraction portion 78,78 ', 178,278,378, thus the weight of crankcase 2 can be suppressed to increase.And, due to internal-combustion engine 1 is arranged on vehicle in the mode making the bent axle 3 of crankcase 2 and main shaft 40, countershaft 41 points to the overall width direction of vehicle, therefore, bent axle 3 and oil sump 61 are separated or between speed changer 4 and oil sump 61 in each next door, in the vehicle that particularly inclination is large in the shake of vehicle fore-and-aft direction, effectively can realize the effect in each next door.

In addition, comprise: the upper limb formed along oil extraction portion 78,78 ', 178,278,378 is formed in the opening of right vertical wall 21R, and by the spill port 60,75 of discharging in the oil around oil extraction portion to the right side room 26R, on the right side of this, room 26R is made up of right vertical wall 21R and the right crankcase cover 25R in the outside being arranged on right vertical wall; On front side of left and right, on rear side of next door 71L, 71R or left and right, the below of next door 72L, 72R forms the opening being formed at right vertical wall 21R, and makes the oil in the room 26R of right side turn back to the oil sump intercommunicating pore 76 of oil sump 61.

Therefore, after oil in oil extraction portion 78,78 ', 178,278,378 is temporarily expelled to rapidly right side room 26R via spill port 60,75 in crankcase 2, to turn back to the oil sump 61 in crankcase 2 via oil sump intercommunicating pore 76 from the lower below each next door, thus the foam that can reduce in oil sump 61, more effectively can prevent from producing air pocket in oil pump 62, oil pressure can be suppressed to change.

In addition, oil extraction portion 78,178,278 is configured in the below of the driven tooth train 45 of speed changer 4, comprise along main shaft 40, the axially extended left and right top wall 73L of countershaft 41,73R, further, left and right top wall 73L, 73R tilt downwards from left and right case periphery wall 22L, 22R towards return opening 74.

Therefore, left and right top wall 73L, 73R are configured in higher position to avoid the interference between driven tooth train 45, thus the maximization in oil extraction portion 78,178,278 becomes possibility.In addition, because the oil on left and right top wall 73L, 73R successfully can turn back to oil sump from return opening 74, therefore, it is possible to do not increase oil capacity and guarantee the oil in oil sump 61, and miniaturization, the lightweight of internal-combustion engine is sought.

Further, the foot-operated actuation gear 85 being bearing in the pedal axle 80 of pedal starting structure 8 and the foot-operated driven gear 49 being bearing in countershaft 41 are engaged with each other via spill port 60.

Therefore, it is possible to lubrication rides actuation gear 85 and foot-operated driven gear 49 well.

Further, right crankcase cover 25R has cooling fin 90.

Therefore, promoted the cooling of the right crankcase cover 25R covering right side room 26R by cooling fin 90, thus promote the cooling of the oil in oil sump 61, on the right side of this, room oil 26R flowing flows to the oil of oil sump intercommunicating pore 76 from forward right side spill port 75 and spill port 60.

And, crankcase 2 is by the right crankcase 2R with right vertical wall 21R, the divided casting housing that the left crankcase 2L with left vertical wall 21L is formed, the right case periphery wall 22R extended in the same direction each other from right vertical wall 21R of right crankcase 2R, right lateral side next door 72R, the left case periphery wall 22L extended in the same direction each other from left vertical wall 21L of upper right quarter wall 73R and left crankcase 2L, left rear side next door 72L, upper left quarter wall 73L is at mating face 27R, 27L engages, and, in oil extraction portion 78, make right crankcase 2R and left crankcase 2L left and right case periphery wall 22L separately, 22R, left and right rear side next door 72L, 72R and left and right top wall 73L, 73R engages on mating face and forms the hollow space closed.

Therefore, by being formed in oil extraction portion 78, there is closed hollow space, ensure that the rigidity of crankcase 2, and achieving lightweight.And, extend in the same direction respectively by making next door 72L, 72R and left and right top wall 73L, 73R on rear side of left and right case periphery wall 22L, 22R, left and right, when casting the crankcase 2 as split case, the halfbody in oil extraction portion 78 can be formed respectively at right crankcase 2R, left crankcase 2L, thus do not increase machining period, oil extraction portion 78 can be formed.

Then, based on Figure 12, the crankcase structure of the second mode of execution of the present invention is described.

Except the oil extraction portion 478 shown in Figure 12, the crankcase structure of the second mode of execution is identical with the first mode of execution, and except the action effect in the oil extraction portion 478 of present embodiment particularly pointed out, identical with the action effect that the first mode of execution plays, therefore, only be described the structure different from the first mode of execution and action effect, other then omit.

The reference character at each position in the second mode of execution is corresponding with the first mode of execution, for different parts, using the rear double figures of the first mode of execution and hundred figure places is the reference character that " 4 " combine, and mark identical reference character, and the description thereof will be omitted for other.

The oil extraction portion 78 of above-mentioned first mode of execution is for being connected left and right top wall 73L, 73R with next door 72L, 72R on rear side of the left and right of left and right crankcase 2L, 2R and being formed.On the other hand, as shown in figure 12, in the oil extraction portion 478 of the second mode of execution, left and right top wall is not directly connected with next door 72L, 72R on rear side of left and right.

The height and position of left rear side next door 72L when separating stopping up and down below pasta S in present embodiment, forwards extends from the rear sidewall of left case periphery wall 22L.

And, between the 72L of left rear side next door tool spaced above, left back midfeather 473a forwards extends from the rear sidewall of left case periphery wall 22L, and, above it, left back top wall 473b is to avoid the shape of the interference between selector fork 56b, from the rear sidewall of left case periphery wall 22L forwards and extend to the below of driven tooth train 45 along the driven tooth train 45 of speed changer 4, left back midfeather 473aL is connected with the front end (diagram right part) of left back top wall 473bL.

Further, the top of pasta S when the major part of left back top wall 473bL is positioned at stopping.

Therefore, at left bent axle in 2R, left case periphery wall 22L, left back midfeather 473aL and left back top wall 473bL form closed annular wall, at the right crankcase 2R also middle identical annular wall forming correspondence, if left and right crankcase 2L, 2R engage, then form the oil extraction portion 478 with enclosed space.

The crankcase of the second mode of execution, owing to having said structure, therefore, plays following effect.

Namely, the feature of the second mode of execution is, have in the crankcase 2 of the internal-combustion engine 1 of oil sump 61 in bottom at supporting crankshaft 3 and speed changer 4, the inlet port 66 being sucked the oil in oil sump 61 by oil pump 62 is arranged on the bottom of oil sump 61, this crankcase structure comprises: arrange and make the oil of lubrication bent axle 3 or speed changer 4 turn back to the return opening 74 of oil sump 61, and separate next door between bent axle 3 and oil sump 61 (next door 71L on front side of left and right, 71R), or separate next door between speed changer 4 and oil sump 61 (next door 72L on rear side of left and right, 72R), and be not directly connected with each next door and be integrally formed in crankcase 2 and be configured in the oil extraction portion 478 with enclosed space on the top of pasta when the internal-combustion engine being stored in the oil of oil sump with appropriate amount stops at least partially.

Therefore, same with above-mentioned first mode of execution, vibrate at internal-combustion engine 1, when tilting, even if the oil of oil sump 61 exceedes each next door 71L, 71R, 72L, 72R because of the variation of pasta, because oil extraction portion 478 is submerged in oil, therefore, it is possible to suppress the pasta in oil sump 61 to decline, thus pasta can be maintained eminence, to prevent inlet port 66 from exposing, and then can prevent from producing air pocket in oil pump 62, oil pressure can be suppressed to change.Therefore, by stablizing and specifying above supply oil pressure, left and right metal bearing 32L, 32R become more suitable in the application of bent axle 3.

In addition, in this second mode of execution, because oil extraction portion 478 forms the enclosed space be not directly connected with each next door 71L, 71R, 72L, 72R, therefore, oil extraction portion 478 can be independently formed with the fore-and-aft direction length in each next door, the shape in oil extraction portion 478 can be made the most suitable with configuration, the increase of the weight of crankcase 2 can be suppressed.

As mentioned above, according to crankcase structure of the present invention, even if be provided with the inclination of vehicle of internal-combustion engine 1, vibration, also can prevent from as much as possible sucking air from inlet port 66, and the pasta of oil sump 61 can be suppressed to decline, therefore, can avoid producing air pocket in oil pump 62, the output oil pressure of control oil pump 62 can become stable, therefore, aspire for stability and specify that metal bearing 32L, 32R of above supply oil pressure application on the bearing of bent axle 3 etc. becomes more suitable.

The invention is not restricted to the content shown in above-mentioned mode of execution, in the scope of purport of the present invention, comprise numerous embodiments, such as, certainly comprise with the mode of execution of possible mode in conjunction with above-mentioned first mode of execution and the second mode of execution.And, the internal-combustion engine with crankcase structure of the present invention not only can be arranged on the two-wheeled of mode of execution, and the internal combustion engine for vehicle that similarly vibrates, tilt can be widely used in, cylinder number is also not limited to single cylinder, the mounting type of internal-combustion engine on vehicle is also not limited to bent axle and points to overall width direction, is also applicable to the internal-combustion engine that bent axle points to car body fore-and-aft direction.

Claims (8)

1. a crankcase structure, have in the crankcase of the internal-combustion engine of oil sump in bottom at supporting crankshaft and speed changer, the inlet port of the oil sucked in described oil sump by oil pump is arranged on the bottom of this oil sump, the feature of this crankcase structure is, comprising:

Described crankcase is the split casting housing be made up of with second crankcase with the second vertical wall first crankcase with the first vertical wall,

The second case periphery wall extended to equidirectional each other from described second vertical wall of the first case periphery wall extended to equidirectional each other from described first vertical wall of described first crankcase, the first next door and the first top wall and described second crankcase, the second next door and the second top wall engage on mating face

Described first next door and described second next door have the return opening making the oil of the described bent axle of lubrication or described speed changer turn back to described oil sump, and separate between described bent axle and described oil sump or between described speed changer and described oil sump;

Described crankcase structure has oil extraction portion, this oil extraction portion is connected with described first next door and described second next door and the internal-combustion engine being configured in the appropriate oil stored by described oil sump at least partially stops time the top of pasta;

Described oil extraction portion is engaged to form closed space to be formed on mating face by described first next door and described second next door, described first top wall and described second top wall and described first case periphery wall and described second case periphery wall.

2. crankcase structure as claimed in claim 1, is characterized in that,

Have pedal axle be bearing in by described crankcase be arranged on outside this crankcase first hood-shaped become the first side room in pedal starting structure;

From described pedal axle direction, described oil extraction portion is configured in the position overlapping with the foot-operated actuation gear of described pedal starting structure.

3. crankcase structure as claimed in claim 1 or 2, is characterized in that,

Be installed on by described internal-combustion engine under the state on vehicle, the transmission shaft of described bent axle and described speed changer is configured to the overall width direction pointing to this vehicle;

Described crankcase structure comprises: a pair vertical wall, and it is made up of the first vertical wall and the second vertical wall that can support described bent axle and described transmission shaft rotatably; Case periphery wall, this pair vertical wall connects by it;

Described oil extraction portion to be connected between described a pair vertical wall and to be connected on described case periphery wall.

4. crankcase structure as claimed in claim 3, is characterized in that, comprising:

Spill port, it forms the opening being formed in described first vertical wall along the upper limb in described oil extraction portion, and make the oil of this oil extraction portion periphery to by described first vertical wall be arranged on outside this first vertical wall first hood-shaped become the first side room in discharge;

Oil sump intercommunicating pore, in the below in described next door, it forms the opening being formed in described first vertical wall, and makes the oil in described first side room turn back to described oil sump.

5. crankcase structure as claimed in claim 3, is characterized in that,

Described oil extraction portion is configured in the below of the speed change gear of described speed changer, and has the axially extended top wall to described transmission shaft, and this top wall tilts downwards from described case periphery wall towards described return opening.

6. crankcase structure as claimed in claim 4, is characterized in that,

Described oil extraction portion is configured in the below of the speed change gear of described speed changer, and has the axially extended top wall to described transmission shaft, and this top wall tilts downwards from described case periphery wall towards described return opening.

7. crankcase structure as claimed in claim 4, is characterized in that,

The foot-operated actuation gear being bearing in the pedal axle of pedal starting structure and the foot-operated driven gear being bearing in described transmission shaft are engaged with each other via described spill port.

8. crankcase structure as claimed in claim 4, is characterized in that,

Described first cover has cooling fin.