CN102168628A - Crankcase structure - Google Patents

Abstract

The invention provides a crankcase structure, which inhibits the change and descending of oil level in the bottom of the casing due to the inclination of an internal combustion engine and enables the oil to rapidly return for preventing the exposure of an oil-sucking opening and preventing an oil pump from generating cavitation. In a supporting crankshaft (3) and a speed changer (4) and a crankcase (2) of an internal combustion engine (1) having an oil sump (61) at the bottom, an oil-sucking opening (66) which sucks the oil in the oil sump (61) through an oil pump (62) is disposed at the bottom of the oil sump (61). The crankcase (2) comprises an oil return port (74) which enables the oil of a lubricating crankshaft (3) or the speed changer (4) to return to the oil sump (61), separating walls (71L, 71R) for separating the crankshaft (3) and the oil sump (61) or separating walls (72L, 72R) for separating the speed changer (4) and the oil sump (61), and oil discharging parts (78, 78') which are connected to the separating walls and are at least partially disposed at the upper part of the oil surface when the internal combustion engine storing proper amount of oil stops.

Description

Crankcase structure

Technical field

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

Background technique

The internal-combustion engine that is provided with oil sump below crankcase comprises lubrication system, and this lubrication system is drawn to be stored in the oil in the oil sump and to be supplied to needs lubricated lubricant housings.The oil that utilizes oil pump in this lubrication system draws in the mechanism, and inlet port is provided with near the bottom surface of oil sump, in order not to be stored in the influence of the oil mass in the oil sump, inlet port is immersed in the oil fully, avoids sucking air.

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

Therefore, not only make the bottom surface of inlet port near oil sump, and, particularly in being installed on the two-wheeled internal-combustion engine that waits vehicle, even in oil sump, store internal-combustion engine with tilting of car body, the oil of the abundance that inlet port also can not expose from pasta.But, internal-combustion engine acutely shake along with car body or the situation quickening, slowing down under, the pasta in the oil sump can change, if change is big, even then inlet port moment also may expose.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 the oil, therefore, the rotation that friction is accompanied by bent axle can increase.

So for example following patent documentation 1 is described, proposed to form the next door technological scheme of the pasta change that stores in the control oil sump by the ground of approximate horizontal in oil sump.

Patent documentation 1:(Japan) spy opens 2008-223880 communique (Fig. 4)

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

In addition, the case periphery wall from the crankcase front and back is formed with the following alar septum of separating up and down to the extension of the inboard of oil sump respectively.And, above the following alar septum of the front side of crankcase, be formed with along the rotating locus of the crank arm last alar septum of convex curvature downwards.By alar septum under these and last alar septum, can suppress to be stored in the change of the pasta in the oil sump.

Extend to direction near each other at the following alar septum of the front and back height place roughly the same in the bottom surface of distance oil sump, and form the connection big opening portion in space up and down between both extension front ends.

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

The last alar septum of bent axle below is erected between a pair of vertical wall of a supporting crankshaft, and the case periphery wall of front side between have gap part, and, the ratio midway of rotating locus downwards the lowest part of bending be formed with the discharge oral area by the rear slightly.

Therefore, the oil that is trapped in alar septum top flows out to the opening portion between the following alar septum in front and back just in time from discharging oral area, the friction of the bent axle that produces thereby the crank arm that reduces rotation immerses in the oil.

But, in above-mentioned patent documentation 1, under the situation that internal-combustion engine tilts significantly, particularly internal-combustion engine all around tilt along with car body or the situation quickening, slow down under, because the pasta in the oil sump can tilt at this moment, therefore, move the top of the easy following alar septum forwards, backwards of oil and the top in next door, top, cause the pasta of oil sump significantly to descend, thereby inlet port is exposed.And, owing to the temporary transient inclination of pasta move on the next door or crankcase and crankcase cover between etc. outer the returning of oil of oil sump can lag behind.Relative therewith, expose in order to prevent inlet port, just need a large amount of oils in reserve, thereby produce following problem: weight increases, and if oil is spilled over to crankshaft room, the friction that then produces along with the rotation of bent axle increases.

In addition, because the exhaust port portion of last alar septum is positioned at higher position, and the oil on the last alar septum is along with the rotation of crank arm, extrude and flow out from discharging oral area, and the opening portion between the following alar septum before and after falling into, therefore, be easy to generate foam, the possibility that foam is positioned at the inlet port suction below this opening portion is very high, and because air pocket, it is unstable that the output oil pressure of oil pump becomes easily.

Particularly, in order on bent axle, to adopt metal bearing, need the above supply oil pressure of regulation,, then cause the internal-combustion engine maximization that becomes if supply with oil pressure to improve by oil pump is maximized.

Summary of the invention

The present invention makes in order to address the above problem, its purpose is to provide a kind of crankcase structure of internal-combustion engine, it can suppress the pasta change in gasoline engine vibration, the oil sump when tilting, suppressing pasta descends, and make owing to the oil that tilts to move promptly returns oil sump and expose to prevent inlet port, suppress to return the oil foaming of oil sump in addition, can prevent to produce cavitation erosion at oil pump.

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

Second aspect invention has pedal axle and is bearing in by described crankcase and is arranged on foot pedal starting mechanism in first hood-shaped first side room that becomes outside this crankcase on the basis of the crankcase structure of first aspect invention record; From the pedal axle direction, described oil extraction portion is configured in the foot-operated actuation gear position overlapped with described foot pedal starting mechanism.

Third aspect invention is on the basis of the crankcase structure of first aspect or second aspect invention record, and under the state that described internal-combustion engine is installed on the vehicle, the transmission shaft of described bent axle and described speed changer is configured to point to the overall width direction of this vehicle; Described crankcase structure comprises: a pair of vertical wall, and it is made of the first vertical wall that can support described bent axle and described transmission shaft rotatably and the second vertical wall; The case periphery wall, it should connect by a pair of vertical wall; Described oil extraction portion is connected between the described a pair of vertical wall and is connected on the described case periphery wall.

The fourth aspect invention is on the basis of the crankcase structure of third aspect invention record, comprise: spill port, it constitutes along the upper limb of described oil extraction portion and is formed on the opening of the described first vertical wall, and the oil that makes this oil extraction portion periphery is to by the described first vertical wall be arranged in first hood-shaped first side room that becomes outside this first vertical wall and discharge; The oil sump intercommunicating pore, below described next door, its formation is formed on the opening of the described first vertical wall, and the oil in described first side room is turned back to described oil sump.

The invention of the 5th aspect is on the basis of the crankcase structure of the third aspect or fourth aspect invention record, described oil extraction portion is configured in the below of the speed change gear of described speed changer, and having axially extended top wall to described transmission shaft, this top wall tilts downwards towards described spill port from described case periphery wall.

The invention of the 6th aspect is on the basis of the crankcase structure of fourth aspect invention record, and the foot-operated actuation gear that is bearing in the pedal axle of foot pedal starting mechanism is engaged with each other via described spill port with the foot-operated driven gear that is bearing in described transmission shaft.

The invention of the 7th aspect is on the basis of the crankcase structure of fourth aspect invention record, and described first cover has cooling fin.

The eight aspect invention is on the basis of the crankcase structure of invention record aspect the 5th, described crankcase is the split casting housing that is made of first crankcase with described first vertical wall and second crankcase with described second vertical wall, the described case periphery wall that extends to equidirectional each other from the described first vertical wall of described first crankcase, the next door, the described case periphery wall that extends to equidirectional each other from the described second vertical wall of top wall and described second crankcase, the next door, top wall engages on the mating face, and described oil extraction portion is by with described first crankcase and second crankcase described case periphery wall separately, next door and top wall engage and the hollow space formation of sealing on the mating face.

The invention of the 9th aspect provides a kind of crankcase structure, have in the crankcase of internal-combustion engine of oil sump at supporting crankshaft and speed changer and in the bottom, to be arranged on the bottom of this oil sump by the inlet port that oil pump sucks the oil in the described oil sump, this crankcase structure is characterised in that, comprise: the next door, its setting makes the oil of lubricated described bent axle or described speed changer turn back to the return opening of described oil sump, and separates between described bent axle and the described oil sump or between described speed changer and the described oil sump; Oil extraction portion, it directly is not connected with described next door and is shaped in described crankcase, and the top of the pasta of at least a portion internal-combustion engine of being configured in the stored an amount of oil of described oil sump when stopping.

Crankcase structure according to the first aspect invention, at gasoline engine vibration, when tilting, even the oil of oil sump surpasses the next door because of the change of pasta, because oil extraction portion is submerged in the oil, therefore, the pasta that also can suppress in the oil sump descends, and makes pasta maintain eminence to prevent exposing of inlet port, thereby can prevent to produce in the oil pump air pocket, can suppress the oil pressure change.Therefore, by supply oil pressure stable and that regulation is above, the application of metal bearing on bent axle becomes more suitable.

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

According to third aspect invention, on the basis of the effect of first aspect or second aspect invention, owing to utilize vertical wall, case periphery wall and next door to constitute oil extraction portion, therefore, the weight that can suppress crankcase increases.In addition, because internal-combustion engine is installed on the vehicle so that the bent axle of crankcase and transmission shaft point to the overall width direction of vehicle, therefore, separate between bent axle and the oil sump in the next door, perhaps between speed changer and the oil sump, particularly in the vibration and the big vehicle that tilts of vehicle fore-and-aft direction, can realize the effect of first aspect invention effectively.

Invent according to fourth aspect, on the basis of the effect that the third aspect is invented, since via spill port with the oil in the oil extraction portion in the crankcase temporarily after discharge in first side room, turn back to oil sump in the crankcase from the lower of next door below via the oil sump intercommunicating pore, therefore, can reduce the foaming in the oil sump, can more effectively prevent to produce cavitation erosion, can suppress the oil pressure change at oil pump.

Invent according to the 5th aspect, on the basis of the effect of the third aspect or fourth aspect invention, by top wall is configured in higher position in order to avoid produce to disturb with speed change gear, the maximization of oil extraction portion becomes possibility, and, because the oil on the top wall can successfully turn back to oil sump from spill port, therefore, can not increase the oil that oil capacity can guarantee that but oil sump is interior, realize miniaturization, the lightweight of internal-combustion engine.

According to the invention of the 6th aspect, on the basis of the effect that fourth aspect is invented, can lubricate foot-operated actuation gear and foot-operated driven gear well.

According to the invention of the 7th aspect, on the basis of the effect that fourth aspect is invented,, therefore, promoted the cooling of the oil in the oil sump owing to promote to cover oil from the cooling of spill port to first cover in the first mobile side room of oil sump intercommunicating pore by cooling fin.

According to the eight aspect invention, on the basis of the effect of invention aspect the 5th,, can guarantee the rigidity of crankcase and seek lightweight by the hollow space that oil extraction portion is designed to seal.In addition, by being extended in the same direction, case periphery wall, next door and top wall form,, can on first crankcase and second crankcase, form the halfbody of oil extraction portion respectively, thereby under the situation that does not increase machining period, can form oil extraction portion during in casting as the crankcase of split housing.

Invent according to the 9th aspect, at gasoline engine vibration, when tilting, even the oil of oil sump surpasses the next door because of the change of pasta, because oil extraction portion is submerged in the oil, therefore, the pasta that also can suppress in the oil sump descends, and makes pasta maintain eminence to prevent exposing of inlet port, thereby can prevent to produce in the oil pump air pocket, can suppress the oil pressure change.Therefore, by supply oil pressure stable and that regulation is above, the application of metal bearing on bent axle becomes more suitable.In addition, because oil extraction portion forms not and the direct-connected enclosed space in next door, therefore, the weight that can control crankcase increases.

Description of drawings

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

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 that the III-III of Fig. 2 looks External view to the right side of first mode of execution of looking, and is the position description figure of the inlet port, oil pump etc. of omissions of detail.

Fig. 4 omits the IV-IV of Fig. 2 of expression left crankcase to the left side (inboard) of the right crankcase of looking view, has omitted each grade of installing and only shows their shaft core position.

Fig. 5 omits the V-V of Fig. 2 of expression right crankcase cover to the right side (outside) of the right crankcase of looking view, has omitted each grade of installing and only shows their shaft core position.

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

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

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

Fig. 9 is with the omission right crankcase of the crankcase of first mode of execution, first variation of Fig. 1 equidirectional and sees that from the inboard right side of left crankcase looks the local figure of section.

Figure 10 is with the omission right crankcase of the crankcase of first mode of execution, second variation of Fig. 1 equidirectional and sees that from the inboard right side of left crankcase looks the local figure of section.

Figure 11 is with the omission right crankcase of the crankcase of first mode of execution the 3rd variation of Fig. 1 equidirectional and sees that from the inboard right side of left crankcase looks the local figure of section.

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

The explanation of reference character

1 internal-combustion engine; 2 crankcases; 2L left crankcase (second crankcase); 2R right crankcase (first crankcase); 3 bent axles; 4 speed changers; 5 cylinder portions; The 6AC generator; 7 multi-disc friction clutches; 8 foot pedal starting mechanisms; 10 pistons; 11 connecting rods; 12 firing chambers; 13 suction ports; 14 relief openings; 15 suction valves; 16 outlet valves; Space in 20 casees; 21L left side vertical wall (the second vertical wall); The right vertical wall (the first vertical wall) of 21R; 22L left side case periphery wall (case periphery wall); The right case periphery wall (case periphery wall) of 22R; 23 crankshaft room; Speed changer chambers 24; 25L left crankcase cover; 25R right crankcase cover (first cover); Chamber, 26L left side; Chamber, 26R right side (first side room); The 27L mating face; The 27R mating face; The right ring-type frame of 28R wall; The 29R mating face; The 30L crank arm; The 30R crank arm; 31 crank pins; 32L left side metal bearing; 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); The 42L left bearing; The 42R right bearing; The 43L left bearing; The 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-changing drum; The 56a selector fork; 57 balancer weights; 58 trunnion shafves; 60 openings (spill port); 61 oil sumps; 62 oil pumps; The upper left wall of 63L oil suction path; The upper right wall of 63R oil suction path; 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 ' front side oil extraction portion (oil extraction portion); 80 pedal axles; 81 left parts; 82a left bearing portion; 82b right bearing portion; 83 right sides; 84 foot-operated arms; 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); 378 front side oil extraction portions (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 and vehicle under the two-wheeled state that waits the internal-combustion engine that present embodiment has been installed on the vehicle towards consistent.Arrow FR represents vehicle front among the figure, and LH represents the vehicle left, and RH represents that vehicle is right-hand, and UP represents the vehicle top.

And the small arrow that is marked on the device of each figure, structural portion schematically shows the flow direction of lubrication oil.

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

Fig. 1 represents the vehicle of present embodiment is installed in attitude on the not shown vehicle with internal-combustion engine 1.

As shown in Figure 1, internal-combustion engine 1 has the cylinder portion 5 of following formation: internal-combustion engine is being installed under the state of vehicle, the axis Y of bent axle 3 and the fore-and-aft direction quadrature of vehicle also point to the width of the carbody direction, bent axle 3 rotates freely, and the earth's axis is bearing in crankcase 2, and this cylinder portion 5 is outstanding upward and the relative vertical curve of cylinder axis X is leaned forward from crankcase 2.Cylinder portion 5 constitutes: overlapping in order and connect cylinder block 50 and cylinder head 51 integratedly at the oblique upper of crankcase 2, on cylinder head 51, cover not shown valve mechanism cover.

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

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

On suction port 13, be connected with not shown throttle-valve body and Fuelinjection nozzle.

II-II profile stretch-out view as Fig. 1 is promptly shown in Figure 2, the crankcase 2 of internal-combustion engine 1 by about the cast housing cut apart constitute, between left crankcase 2L (" second crankcase " of the present invention) and right crankcase 2R (" first crankcase " of the present invention), be formed with space 20 in the 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) in the case, surround the space that forms by left and right sides case periphery wall 22L, 22R (" case periphery wall " of the present invention), space 20 is positioned at a space of front and back and connection mutually in this case for crankshaft room 23 and speed changer chamber 24, wherein, the crank arm 30L of the counterweight that constitutes bent axle 3 accommodates in crankshaft room 23,30R, the speed changer 4 that constitutes normal mesh gear gear is accommodated in speed changer chamber 24.

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

The lateral part root of bent axle wall 30L, the 30R of bent axle 3 rotates freely via left and right sides metal bearing 32L, 32R, and the earth's axis is bearing on relative to each other left and right sides vertical wall 21L, the 21R of left crankcase 2L and right crankcase 2R.When adopting metal bearing, need the stable and supply oil pressure more than the regulation of lubricant oil.

In the 26L of chamber, left side from this left side metal bearing 32L on the outstanding bent axle 3 of left, the cam chain driving sprocket wheel 33 of active valve mechanism is installed, and is provided with AC generator 6 in left end side, 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 sides vertical wall 21L of 2R, between the two vertical walls of the rear extension of 21R, with the axis Y of bent axle 3 abreast, via left and right sides bearing 42L, 42R rotates the main shaft 40 (" transmission shaft " of the present invention) that the earth's axis freely is supported with speed changer 4, via left and right sides bearing 43L, 43R rotates the countershaft 41 (" transmission shaft " of the present invention) that the earth's axis freely is supported with speed changer 4, and, the gear train 44 that is bearing in main shaft 40 meshes each corresponding gear all the time with the driven tooth train 45 (" speed change gear " of the present invention) that is bearing in countershaft 41, and is housed in the speed changer chamber 24.

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

Though 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 sides, the main driven gear 46 of multi-disc friction clutch 7 sides, but, multi-disc friction clutch 7 constitutes: in the gear of speed changer 4 switches, the rotating power with bent axle 3 does not transmit to speed changer 4, be in the neutral state, in the gear finishing switching of speed changer 4, the rotating power of bent axle 3 is transmitted to speed changer 4.

Left vertical wall 21L is being connected and to the left part of the outstanding countershaft 41 in outside, is embedded with output sprocket 47 to left, and volume hangs with rear wheel drive with chain 48 on output sprocket 47.

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

In speed changer chamber 24, the foot-operated driven gear 49 that is driven by foot pedal starting mechanism 8 be entrenched in the approaching countershaft 41 of right bearing 43R on.

In the 26R of chamber, right side, the left part 81 of the pedal axle 80 of foot pedal starting mechanism 8 is bearing on the 82a of left bearing portion on the right side (outside) of the right vertical wall 21R that is arranged at right crankcase 2R, right part 83 is bearing on the right crankcase cover 25R via the 82b of right bearing portion, and connect right crankcase cover 25R, and foot-operated arm 84 is installed.

On pedal axle 80 with left part 81 in abutting connection with and the chimeric foot-operated actuation gear 85 that has with foot-operated driven gear 49 engagements, foot-operated driven gear 49 and foot-operated actuation gear 85 separately are positioned at the inboard and the outside of right vertical wall 21R, are meshing with each other via the opening 60 that is arranged on right vertical wall 21R (" spill port 60 " described later).

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 under, than countershaft 41 low position configuration speed-changing drum 55 is arranged.Speed-changing drum 55 is rotated by not shown unsteady axle (シ Off ト ス ピ Application De Le), select to carry out effectively the gear mesh of transmission of power so that selector fork 56a, 56b move each meshed gears centering of the gear train 44 of speed changer 4 and driven tooth train 45, carry out speed change thus.

And in the place ahead of bent axle 3, trunnion shaft 58 rotations with balancer weight 57 are erected on left and right sides vertical wall 21L, the 21R freely, and are driven by bent axle 3 rotations via not shown gear.

And, as shown in Figure 1, in crankcase 2, left and right sides case periphery wall 22L, the 22R of left and right sides crankcase 2L, the 2R of 24 tops, speed changer chamber forms ventilation and protrudes wall 87 across left and right sides crankcase 2L, 2R protrude upward, ventilation is protruded the inside of wall 87 by ventilation chamber diapire and 24 separations of speed changer chamber, thereby forms ventilation chamber 89.

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

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

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

In addition, Fig. 5 is that (outside) figure is looked on the right side of pulling down behind the right crankcase cover 25R of right crankcase 2R, be provided with the right ring-type frame wall 28R of the tab-like one-tenth in side to the right at right crankcase 2R, and be formed with the ring-type mating face 29R (part shown in the trellis shade) of itself and right crankcase cover 25R in its its right end face with right vertical wall 21R.

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, thereby portion is formed with chamber, right side 26R within it.

As shown in Figure 1 and Figure 4, left and right sides case periphery wall 22L, the 22R of left and right sides crankcase 2L, 2R cover periphery in the following manner: pass through the below of bent axle 3 and the lower direction rear bending extension of speed changer 4 from the place ahead of trunnion shaft 58, and the rear of process speed changer 4 is bending extension upward, thereby arrives the top of speed changer 4.

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

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

In oil sump 61, be necessary to store an amount of oil all the time, in Fig. 1 and Fig. 4, represent the average pasta S of an amount of oil when internal-combustion engine stops (below, brief note is " pasta S when stopping " in this manual) with double dot dash line.

When internal-combustion engine 1 stops, if pasta is positioned at this when stopping pasta S up and down near, then oil is an amount of.

If internal-combustion engine 1 work, then the oil in the oil sump 61 are drawn by the driving of oil pump 62 (with reference to Fig. 3), are supplied to each lubricant housings, and therefore, the pasta during work is in the position of pasta S when being lower than Fig. 1 and shown in Figure 4 stopping 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, rearward be connected integratedly and extend and be formed with the upper right wall 63R of oil suction path along the bottom surface with right vertical wall 21R from the front panel of right case periphery wall 22R.

The upper right wall 63R of oil suction path and be formed on symmetrically left crankcase 2L upper left wall 63L (with reference to Fig. 1) butt of oil suction path and and the bottom surface of oil sump 61 between be formed with oil suction path 64.

At this moment, sealed by oil suction path left and right sides rear wall 65L, 65R about the flattened rectangular opening that forms between the rear end of oil suction path left and right sides upper wall 63L, 63R and the bottom surface of oil sump 61, and form inlet port 66 (with reference to Fig. 6) in central authorities.

At the right flank (outside) of the right vertical wall 21R of right crankcase 2R shown in Figure 5, be formed with in the right ring-type frame wall 28R with the rectangular opening 67 of flattened rectangular perforation, 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 oil access 69 is bored a hole at right vertical wall 21R along the lower edge of the upper right wall 63R of oil suction path.

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

Therefore, as shown in Figure 3, if internal-combustion engine 1 is worked and is driven oil pump 62, then near the oil the bottom surface of the oil sump 61 in the crankcase 2 flows into oil suction path 64 from inlet port 66, and via in the oily access 69 suction rectangular openings 67, and be filtered, thereby sucked by oil pump 62 by the oily fuel filters 68 that are installed in the rectangular opening 67.The oil pump 62 of present embodiment is a trochoid pump.

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

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

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

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

The interval that has regulation between the rear end of the connecting part of the front end of left rear side next door 72L and upper left quarter wall 73L and front left side next door 71L disposes speed-changing drum 55 in this compartment.

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, left rear side next door 72L and the upper left quarter wall 73L of the inner face of left crankcase 2L.

Therefore, if left crankcase 2L and right crankcase 2R zoarium, then about before alar septum 71L, 71R constitute mating face butt each other and become the preceding alar septum (" next door " of the present invention) of same one.

In addition, about back alar septum 72L, 72R constitute mating face butt each other and become the back alar septum (" next door " of the present invention) of same one, left and right sides top wall 73L, 73R constitute mating face butt each other and become the top wall (" top wall " of the present invention) of same one.

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

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

Oil extraction portion 78 with about back alar septum 72L, 72R be connected, the major part at its rear portion is configured in the top of pasta S when stopping.

Therefore, when internal-combustion engine 1 tilted rearward, even the oil of oil sump 61 because of pasta rearward move to wait change to surpass about back alar septum 72L, 72R because oil extraction portion 78 is submerged in the oil, therefore, also can suppress the interior pastas decline of oil sump 61.In addition, under the situation of internal-combustion engine 1 lateral inclination, a part that is submerged in the oil extraction portion 78 in the oil also obtains identical effect.

Therefore, the pasta in the oil sump 61 can be maintained higher position, thereby can prevent that inlet port 66 from exposing, can prevent to produce air pocket in the oil pump 62, can suppress the change of oil pressure.

In addition, since about before the rear end side of alar septum 71L, 71R be positioned at the top of pasta S when stopping, therefore, under the situation that internal-combustion engine 1 forwards tilts, about the oil of oil sump 61 waits change to surpass because of pasta forwards moves when preceding alar septum 72L, 72R, because rear end side is submerged in the oil, therefore, has the function of the front side oil extraction portion 78 ' (" oil extraction portion " of the present invention) of the pasta decline in the control oil sump 61.Under the situation of internal-combustion engine 1 lateral inclination, a part that is submerged in the oil extraction portion 78 ' in the oil also obtains identical effect.

Fig. 9 to Figure 11 represents first variation to the, three variation of the crankcase structure of present embodiment.

Each variation illustrates the variation of oil extraction portion 78 or front side oil extraction portion 78 ', and is 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 the annular wall of sealing, and right crankcase 2R also forms corresponding identical annular wall, thereby constitute the oil extraction portion 78 with enclosed space.Relative therewith, in first variation shown in Figure 9, in left crankcase 2L, part excision with left case periphery wall 22L, 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), form the recess of opening to the outside of crankcase 2, in right crankcase 2R, form the same structure corresponding, thereby constitute oil extraction portion 178 with it.

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

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

By this oil extraction portion 278, not only can realize prevent the effect that pasta descend identical, and by the metallic material that use with above-mentioned first mode of execution more, the cooling that can improve crankcase 2, 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 of the oil extraction portion 78 of above-mentioned first mode of execution, form the bottom in front left side next door 371L (" next door " of the present invention) thickly, in right crankcase 2R, also form the same structure relative, thereby constitute front side 378 (" oil extraction portions " of the present invention) of oil extraction portion with it.

In the first embodiment, about before the rearward end of alar septum 71L, 71R be positioned at the top of pasta S when stopping, about before alar septum 71L, 71R itself have certain function as front side oil extraction portion 78 '.But, owing in the 3rd variation, constituted the bigger front side oil extraction portion 378 of volume, therefore, under the situation that internal-combustion engine 1 forwards tilts, even the oil of oil sump 61 because of pasta forwards move to wait change to surpass about preceding alar septum, because front side oil extraction portion 378 is submerged in the oil, therefore, the pasta that also can suppress in the oil sump 61 descends.Under the situation of internal-combustion engine 1 lateral inclination, a part that is submerged in the front side oil extraction portion 378 in the oil plays same effect.

Therefore, the pasta in the oil sump 61 can be maintained the higher position, prevent that inlet port 66 from exposing, can prevent to produce air pocket in the oil pump 62, can suppress the oil pressure change.

Above-mentioned first to the 3rd variation is not limited to above-mentioned mode, can implement by the mode of possible combination in any, and for example, the 3rd variation can combine and implement with second variation or the 3rd variation.

In addition, the oil extraction portion 78 of present embodiment is in left crankcase 2L side, in by the scope of left case outer circumferential side 22L, left rear side next door 72L and upper left quarter wall 73L encirclement and on the whole width at left crankcase 2L, form (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 foot pedal starting mechanism 8 is positioned at the zone of the oil extraction portion 78 that is surrounded by right case periphery wall 22R, right lateral side next door 72R and upper right quarter wall 73R in overlapping mode.

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

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

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

Vertical wall 21R around configuration by above-mentioned pedal axle 80 and the foot-operated actuation gear 85 direction left forms the shape that step protrudes, foot-operated driven gear 49 and foot-operated actuation gear 85 separately are positioned at the inboard and the outside of right vertical wall 21R, but, opening 60 via the stepped part that is arranged on right vertical wall 21R is engaged with each other, therefore, help the miniaturization (with reference to Fig. 2) of crankcase 2 even internal-combustion engine 1.In addition, opening 60 becomes side room 26R to the right and promptly discharges and wait in the lubricated speed changer chamber 24 and at the spill port 60 (" spill port " of the present invention) that arrives the oil on left and right sides top wall 73L, the 73R below the 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, about the joint of front end of back alar septum 72L, 72R and left and right sides top wall 73L, 73R have the interval of regulation and form rectangular aperture with the rear end of preceding alar septum 71, this rectangular aperture constitutes the return opening 74 that the oil that lubricates 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-changing drum 55 is configured in the position (with reference to Fig. 1) of stopping up rectangular aperture.Therefore, the oil that flows to oil sump 61 from return opening 74 is owing to speed-changing drum 55 reduces inflow velocity, influx, most of oil about arrival on back alar septum 72L, 72R and left and right sides top wall 73L, the 73R suppresses the foaming that produces from the oil that the return opening 74 of higher position directly flows down from spill port 60 and following forward right side spill port 75 side room 26R discharge to the right.

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

And in right vertical wall 21R, chadless is provided with oil sump intercommunicating pore 76 (drawing the some part) below return opening 74.As from the outside (right side) see the shown in Figure 5 of right crankcase 2R, oil sump intercommunicating pore 76 (" oil sump intercommunicating pore " of the present invention) formation above the lower portion of right ring-type frame wall 28R.

Therefore, wait in the lubricated crankshaft room 23 and arrive about before oil on alar septum 71L, the 71R, via forward right side spill port 75 rapidly to the right side room 26R discharge, and in the 26R of chamber, right side, flow down and arrive ring-type frame wall 28R lower portion above.

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

Therefore, because most oil flows into oil sumps 61 at lower position from the oil sump intercommunicating pore 76 of the side that is 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, be provided with front left side spill port 77 (drawing a some part) at the following side perforation of left front sidewall 71L.As shown in Figure 7, the foot of chamber, the left side 26L between front left side spill port 77 and left crankcase 2L and the left crankcase cover 25L is communicated with, and the oil of AC generator 6 grades in the lubricated left side chamber 26L promptly flows into the bottom in the crankcase 2, and turns back to oil sump 61.

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

Especially, because the oil of lubricated crankshaft room 23 sides is almost all discharged from forward right side spill port 75, therefore, preferably make near the place ahead part of the forward right side spill port 75 of forward right side spill port 75 positions of the right crankcase cover 25R that forms chamber, the right side 26R that oil flows down and fully cool off, to realize the cooling of oil.

Therefore, as shown in Figure 8, in the crankcase structure of present embodiment, cooling fin 90 is set among the right crankcase cover 25R the place ahead of the position corresponding with multi-disc friction clutch 7, promptly with the position of forward right side spill port 75 approaching with outsides crankshaft room's 23 respective side.In addition, the left that is formed on crankcase cover 25R to the right between the cooling fin 90 has improved cooling (air cooling) effect of right crankcase cover 25R in the ditch portion 91 of (interior side direction) depression.

Because the crankcase of this first mode of execution has aforesaid structure, therefore realized following effect.

Though average pasta when internal-combustion engine 1 stops has been shown, pasta S when stopping in Fig. 1 and Fig. 4, but, in the work of internal-combustion engine 1, oil is supplied with to each lubricant housings, it is quite low that pasta becomes, for example, than about before alar septum 71L, 71R and about back alar septum 72L, 72R low, therefore, even the oil that is stored in the oil sump 61 flows along with the swing of internal-combustion engine 1 with car body, pasta also can by about before alar septum 71L, 71R and about back alar septum 72L, 72R control, suppress flowing of oil effectively.

Especially, when acceleration and deceleration etc. or vehicle tilt forward and back, under the situation of swinging significantly before and after the oil in oil sump 61, by the front panel inner face with left and right sides case periphery wall 22L, 22R be connected about before alar septum 71L, 71R, can stop oil to reflux than the front panel inner face of 22L, 22R and move in the crankshaft room 23 along left and right sides case periphery.And, by the rear sidewall inner face with left and right sides case periphery wall 22L, 22R be connected about back alar septum 72L, 72R, can stop oil to reflux and move in the speed changer chamber 24, and then stop and arrive in the ventilation chamber 89 along the rear sidewall inner face of left and right sides case periphery wall 22L, 22R.Therefore, can suppress the friction increase of oil and bent axle 3, trunnion shaft 58 and speed changer 4 as much as possible.

And, by about before alar septum 71L, 71R and about the moving of back alar septum 72L, 72R control pasta, thereby prevent to expose along the inlet port 66 of the bottom surface configuration of oil sump 61, can prevent that oil pump 62 from sucking air and producing air pocket from inlet port 66.

And, the crankcase structure of present embodiment is characterised in that, have in the crankcase 2 of internal-combustion engine 1 of oil sump 61 at supporting crankshaft 3 and speed changer 4 and in the bottom, to be arranged on the bottom of oil sump 61 by the inlet port 66 that oil pump 62 sucks the oil in the oil sump 61, this crankcase structure comprises: the return opening 74 that the oil that makes lubricated bent axle 3 or speed changer 4 turns back to oil sump 61 is set, and separate next door between bent axle 3 and the oil sump 61 (about before alar septum 71L, 71R), perhaps separate next door between speed changer 4 and the oil sump 61 (about back alar septum 72L, 72R), be connected and with each next door and at least a portion is configured in the oil extraction portion 78 on the top of pasta S when stopping, 78 ', 178,278,378.

Therefore, under the situation of internal-combustion engine 1 swing, inclination, even the oil of oil sump 61 surpasses each next door 71L, 71R, 72L, 72R because of the change of pasta, because oil extraction portion 78,78 ', 178,278,378 is submerged in the oil, therefore, the pasta that can suppress in the oil sump 61 descends, thereby pasta can be maintained eminence, prevent that inlet port 66 from exposing, can prevent to produce air pocket in the oil pump 62, can suppress oil pressure and change.Therefore, by supply oil pressure stable and that regulation is above, left and right sides metal bearing 32L, 32R are useful on the bent axle 3 well.

In addition, by crankcase 2 be arranged in chamber, the right side 26R that the right crankcase cover 25R in crankcase 2 outsides constitutes, foot pedal starting mechanism 8 with supporting pedal axle 80, from pedal axle 80 directions, oil extraction portion 78,178,278 is configured in foot-operated actuation gear 85 position overlapped with foot pedal starting mechanism 8.

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

In addition, internal-combustion engine 1 is being installed under the state of vehicle, the main shaft 40 of bent axle 3 and speed changer 4, countershaft 41 point to the overall width direction of vehicle and dispose.Crankcase 2 constitutes and comprises: a pair of vertical wall, and the right vertical wall 21R and the left vertical wall 21L of supporting crankshaft 3 and main shaft 40, countershaft 41 constitute by rotating freely for it; Left and right sides case periphery wall 22L, 22R, it connects a pair of vertical wall 21L, 21R.Be connected between oil extraction portion 78,78 ', 178,278,378 and a pair of vertical wall 21L, the 21R, and be connected with left and right sides case periphery wall 22L, 22R.

Therefore, utilize left and right sides vertical wall 21L, 21R, left and right sides case periphery wall 22L, 22R and about before alar septum 71L, 71R or about back alar septum 72L, 72R constitute oil extraction portion 78,78 ', 178,278,378, thereby the weight that can suppress crankcase 2 increases.And, because with internal-combustion engine 1 so that the mode that the bent axle 3 of crankcase 2 and main shaft 40, countershaft 41 points to the overall width direction of vehicles be installed on the vehicle, therefore, separate between bent axle 3 and oil sump 61 or speed changer 4 and the oil sump 61 in each next door, particularly shake and in the big vehicle of inclination, can realize the effect in each next door effectively at the vehicle fore-and-aft direction.

In addition, comprise: constitute the opening that is formed on right vertical wall 21R along the upper limb of oil extraction portion 78,78 ', 178,278,378, and with the spill port 60,75 that the oil around the oil extraction portion is discharged in the 26R of side room to the right, this chamber, right side 26R is made of right vertical wall 21R and the right crankcase cover 25R that is arranged on the outside of right vertical wall; About before alar septum 71L, 71R or about back alar septum 72L, 72R below constitute and be formed at the opening of right vertical wall 21R, and make oil in the 26R of chamber, right side turn back to the oil sump intercommunicating pore 76 of oil sump 61.

Therefore, after oil in the oil extraction portion 78,78 ', 178,278,378 temporarily is expelled to chamber, right side 26R via spill port 60,75 rapidly in the crankcase 2, turn back to oil sump 61 in the crankcase 2 from the lower of below, each next door via oil sump intercommunicating pore 76, thereby can reduce the foam in the oil sump 61, can more effectively prevent to produce air pocket in the oil pump 62, can suppress the oil pressure 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 axially extended left and right sides top wall 73L, 73R along main shaft 40, countershaft 41, and left and right sides top wall 73L, 73R tilt downwards towards return opening 74 from left and right sides case periphery wall 22L, 22R.

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

And the foot-operated actuation gear 85 that is bearing in the pedal axle 80 of foot pedal starting mechanism 8 is engaged with each other via spill port 60 with the foot-operated driven gear 49 that is bearing in countershaft 41.

Therefore, can lubricate foot-operated actuation gear 85 and foot-operated driven gear 49 well.

And right crankcase cover 25R has cooling fin 90.

Therefore, promote to cover the cooling of the right crankcase cover 25R of chamber, right side 26R by cooling fin 90, thereby promote the cooling of the oil in the oil sump 61, flowing at this chamber, right side oil 26R 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, divided casting housing with left crankcase 2L formation of left vertical wall 21L, the right case periphery wall 22R that extends 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 that extends 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 sides case periphery wall 22L separately, 22R, about back alar septum 72L, 72R and left and right sides top wall 73L, 73R engages and the hollow space of formation sealing on the mating face.

Therefore, by oil extraction portion 78 is constituted the hollow space with sealing, guaranteed the rigidity of crankcase 2, and realized lightweight.And, by make left and right sides case periphery wall 22L, 22R, about back alar septum 72L, 72R and left and right sides top wall 73L, 73R extend in the same direction respectively, in casting during as the crankcase 2 of split case, can form the halfbody of oil extraction portion 78 at right crankcase 2R, left crankcase 2L respectively, thereby do not increase machining period, can form oil extraction portion 78.

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

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

The reference character at each position in second mode of execution is corresponding with first mode of execution, for different parts, use is the reference character of " 4 " combination with the back double figures and hundred figure places of first mode of execution, for the identical reference character of other marks, and omits its explanation.

The oil extraction portion 78 of above-mentioned first mode of execution forms for left and right sides top wall 73L, 73R are connected with back alar septum 72L, 72R about left and right sides crankcase 2L, 2R.Relative therewith, as shown in figure 12, in the oil extraction portion 478 of second mode of execution, left and right sides top wall with about back alar septum 72L, 72R directly be not connected.

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

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

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

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

Therefore the crankcase of second mode of execution, plays following effect owing to have said structure.

Promptly, second mode of execution is characterised in that, have in the crankcase 2 of internal-combustion engine 1 of oil sump 61 at supporting crankshaft 3 and speed changer 4 and in the bottom, to be set at the bottom of oil sump 61 by the inlet port 66 that oil pump 62 sucks the oil in the oil sump 61, this crankcase structure comprises: the return opening 74 that the oil that makes lubricated bent axle 3 or speed changer 4 turns back to oil sump 61 is set, and separate next door between bent axle 3 and the oil sump 61 (about before alar septum 71L, 71R), perhaps separate next door between speed changer 4 and the oil sump 61 (about back alar septum 72L, 72R), and directly be not connected and be integrally formed in the oil extraction portion 478 that crankcase 2 and at least a portion are configured in the internal-combustion engine that is stored in the oil of oil sump with appropriate amount top of pasta when stopping with enclosed space with each next door.

Therefore, same with above-mentioned first mode of execution, under the situation of internal-combustion engine 1 vibration, inclination, even the oil of oil sump 61 surpasses each next door 71L, 71R, 72L, 72R because of the change of pasta, because oil extraction portion 478 is submerged in the oil, the pasta that therefore can suppress in the oil sump 61 descends, thereby pasta can be maintained eminence, preventing that inlet port 66 from exposing, and then can prevent to produce air pocket in the oil pump 62, can suppress the oil pressure change.Therefore, by supply oil pressure stable and that regulation is above, left and right sides 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 not and each next door 71L, 71R, the direct-connected enclosed space of 72L, 72R, therefore, can irrespectively form oil extraction portion 478 with the fore-and-aft direction length in each next door, can make the shape and the configuration of oil extraction portion 478 the most suitable, can suppress the increase of the weight of crankcase 2.

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

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

Claims (9)

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

Next door, its setting make the oil of lubricated described bent axle or described speed changer turn back to the return opening of described oil sump, and separate between described bent axle and the described oil sump or between described speed changer and the described oil sump;

Oil extraction portion, the top of the pasta the when internal-combustion engine that it is connected with described next door and at least a portion is configured in the stored an amount of oil of described oil sump stops.

2. as the crankcase structure of claim 1 record, it is characterized in that,

Having pedal axle is bearing in by the foot pedal starting mechanism in described crankcase and first hood-shaped first side room that becomes that is arranged on this crankcase outside;

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

3. as the crankcase structure of claim 1 or 2 records, it is characterized in that,

Under the state that described internal-combustion engine is installed on the vehicle, the transmission shaft of described bent axle and described speed changer is configured to point to the overall width direction of this vehicle;

Described crankcase structure comprises: a pair of vertical wall, and it is made of the first vertical wall that can support described bent axle and described transmission shaft rotatably and the second vertical wall; The case periphery wall, it should connect by a pair of vertical wall;

Described oil extraction portion is connected between the described a pair of vertical wall and is connected on the described case periphery wall.

4. as the crankcase structure of claim 3 record, it is characterized in that, comprising:

Spill port, it constitutes along the upper limb of described oil extraction portion and is formed on the opening of the described first vertical wall, and the oil that makes this oil extraction portion periphery is to by the described first vertical wall be arranged in first hood-shaped first side room that becomes outside this first vertical wall and discharge;

The oil sump intercommunicating pore, below described next door, its formation is formed on the opening of the described first vertical wall, and makes the oil in described first side room turn back to described oil sump.

5. as the crankcase structure of claim 3 or 4 records, it 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 towards described spill port from described case periphery wall.

6. as the crankcase structure of claim 4 record, it is characterized in that,

The foot-operated actuation gear that is bearing in the pedal axle of foot pedal starting mechanism is engaged with each other via described spill port with the foot-operated driven gear that is bearing in described transmission shaft.

7. as the crankcase structure of claim 4 record, it is characterized in that,

Described first cover has cooling fin.

8. as the crankcase structure of claim 5 record, it is characterized in that,

Described crankcase is the split casting housing that is made of first crankcase with described first vertical wall and second crankcase with described second vertical wall,

Described case periphery wall, next door, the top wall of extending to equidirectional each other from the described first vertical wall of described first crankcase engage on the mating face to described case periphery wall, next door, the top wall that equidirectional extends from the described second vertical wall each other with described second crankcase

The hollow space of sealing constitutes by described first crankcase and described second crankcase described case periphery wall, next door and top wall are separately engaged on the mating face in described oil extraction portion.

9. crankcase structure, have in the crankcase of internal-combustion engine of oil sump at supporting crankshaft and speed changer and in the bottom, to be arranged on the bottom of this oil sump by the inlet port that oil pump sucks the oil in the described oil sump, this crankcase structure is characterised in that, comprising:

Next door, its setting make the oil of lubricated described bent axle or described speed changer turn back to the return opening of described oil sump, and separate between described bent axle and the described oil sump or between described speed changer and the described oil sump;

Oil extraction portion, it directly is not connected with described next door and is shaped in described crankcase, and the top of the pasta of at least a portion internal-combustion engine of being configured in the stored an amount of oil of described oil sump when stopping.

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