CN1530521A

CN1530521A - Topping cam engine

Info

Publication number: CN1530521A
Application number: CNA2004100295292A
Authority: CN
Inventors: 田中宏幸
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2003-03-18
Filing date: 2004-03-18
Publication date: 2004-09-22
Anticipated expiration: 2024-03-18
Also published as: EP1460238A2; JP2004278447A; ES2301934T3; CN1317488C; TWI240040B; TW200424424A; EP1460238B1; JP4025667B2; EP1460238A3

Abstract

To compact a combustion chamber and downsize a cylinder head in an overhead cam engine, wherein a cam shaft is provided between intake and exhaust valve springs and is rotatably supported by the cylinder head; and wherein the cam shaft is provided with a first cam to drive one of an intake valve and an exhaust valve and is provided with a second cam to drive the other of the intake valve and the exhaust valve. A cylinder head 16F supports a cam shaft 131 with its axis line approximately disposed above a cylinder axis line. A second cam 143 is disposed between intake and exhaust valve springs 129 and 130 and is formed to be smaller than a first cam 142. The first cam 142 is disposed farther from the position between the intake and exhaust valve springs 129 and 130 along the direction of the axis line of the cam shaft 131.

Description

The overhead cam h type engine h

Technical field

The present invention relates to a kind of overhead cam h type engine h, wherein, on the cylinder head of a part that constitutes engine main body, can be provided with suction valve and outlet valve with opening and closing, it is energized towards closing the valve direction by air inlet side and exhaust side valve spring, be arranged on the camshaft that is rotatably supported between described suction valve side valve spring and the exhaust valve side valve spring on the described cylinder head, be provided with first cam that is used for driving one of suction valve and outlet valve and be used for driving suction valve and another second cam of outlet valve.

Background technique

Known for example have following overhead cam h type engine h in patent documentation 1 grade, wherein, in order to ensure the space that spark plug is set, the camshaft that is arranged between suction valve and the outlet valve is leaned on from cylinder axis to a lateral deviation of suction valve and outlet valve.

Patent documentation 1

Special public clear 59-25861 communique

But in described prior art, because the formed valve angle of valve rod of suction valve and outlet valve is bigger, so be unfavorable for the increase that reduces to cause the cylinder head size of the overall dimensions of firing chamber.

Summary of the invention

The present invention In view of the foregoing makes invention, and its purpose is to provide a kind of overhead cam h type engine h, and it can reduce the overall dimensions of firing chamber and make the cylinder head miniaturization.

In order to realize described purpose, the described invention of first aspect present invention relates to a kind of overhead cam h type engine h, wherein, on the cylinder head of a part that constitutes engine main body, can be provided with suction valve and outlet valve with opening and closing, this suction valve and outlet valve are by spiral helicine air inlet side and exhaust side valve spring, energized towards closing the valve direction, be arranged on the camshaft that is rotatably supported between described suction valve side valve spring and the exhaust valve side valve spring on the described cylinder head, be provided with first cam and second cam, this first cam is used for driving one of suction valve and outlet valve, this second cam be used for driving suction valve and outlet valve another, it is characterized in that, described camshaft, its axis is configured on the cylinder axis basically, and be supported on the described cylinder head, be arranged at second cam between air inlet side and the exhaust side valve spring less than first cam, first cam is arranged at along the direction of the axis of described camshaft, the position of staggering between described relatively air inlet side and the exhaust side valve spring.

By such scheme, can be in the interference of avoiding between first and second cams and air inlet side and the exhaust side valve spring, set the angle of the valve shaft of suction valve and outlet valve less, the overall dimensions that can reduce the firing chamber obtains higher compression ratio, reduce to include the overall dimensions of the valve transmission device of camshaft simultaneously, and then reduce the size of cylinder head.

And, the described invention of second aspect present invention, scheme according to the described invention of first aspect present invention, it is characterized in that, both sides at described camshaft, direction a pair of respectively suction valve and outlet valve arranged side by side along the axis of this camshaft can be arranged on the described cylinder head with opening and closing, according to described scheme, overhead cam h type engine h for 4 valves, can reduce the overall dimensions of firing chamber, obtain higher compression ratio, reduce to comprise the overall dimensions of the valve transmission device of camshaft, and then reduce the size of cylinder head.

The described invention of third aspect present invention, the scheme of the first or two described inventions in aspect according to the present invention, it is characterized in that, the engine main body that comprises described cylinder head, described cylinder axis tilts forward and the axis of bent axle is in the attitude of level, rear in the front-wheel of dilly is installed on the vehicle frame, first swing arm that is driven in described first and second cams one is supported swingably by having first swing axis that parallels to the axis with described camshaft, be driven in described first and second cams supporting swingably of another by having second swing axis that parallels to the axis with described camshaft, this second swing axis is arranged at the rear of first swing axis, distance between second swing axis and the described bent axle is less than the distance between first swing axis and the described bent axle, according to described scheme, although cylinder axis is towards preceding tilting, still can shorten the distance of the front bottom end from the bent axle to the engine main body as best one can, can be in the interference of avoiding front-wheel, make engine main body near front wheel side, can shorten the wheel base of dilly, maybe can must be longer with the travel settings of front-wheel.

The described invention of fourth aspect present invention, scheme according to the described invention of third aspect present invention, it is characterized in that, the roller that axle Zhi Youyu first cam rolls and contacts in described first swing arm, described second swing arm is provided with the cam roller that contacts with described second cam slide, according to described scheme, avoid making and the less cam slide in space is set and is arranged at second cam slide between air inlet side and the exhaust side valve spring and contacts the situation that the angle of the valve shaft of suction valve and outlet valve increases, and can reduce the size of cylinder head, in addition, owing to be arranged at the position of staggering between relative air inlet side and the exhaust side valve spring, therefore by making the contact of rolling of the bigger roller in space is set on first cam that described angle is not impacted, and can helps the reduction of the frictional loss of valve transmission device.

The described invention of the present invention the 5th and the 6th aspect, according to the present invention the 3rd or the scheme of the described invention of fourth aspect, it is characterized in that, described engine main body is V-shaped, it has towards the front assembly of the described cylinder axis that preceding tilts and the rear assembly of seeing from the side with the V-shaped cylinder axis that intersects of described cylinder axis, according to described scheme, avoid being installed in the engine main body of the V-type engine on the dilly, the cylinder head that this engine main body had and the interference of front-wheel, avoid the wheel base of dilly to increase thus, the wheel stroke of front-wheel shortens, simultaneously, engine main body is configured in lower position as far as possible, can guarantees the space of miscellaneous part above engine main body, reduce the height of driver with seat.

If it is such as described, adopt the described invention of first aspect present invention, can set the angle of the valve shaft of suction valve and outlet valve lessly, the overall dimensions that can reduce the firing chamber obtains higher compression ratio, can reduce simultaneously to include camshaft the valve transmission device overall dimensions so that reduce the size of cylinder head.

And the described invention of second aspect present invention is at the overhead cam h type engine h of 4 valves, can reduce the overall dimensions of firing chamber, obtain higher compression ratio, and can reduce to comprise the overall dimensions of the valve transmission device of camshaft, and then reduce the size of cylinder head.

The described invention of third aspect present invention, although cylinder axis is towards preceding tilting, still can shorten the distance of bent axle as best one can to the front bottom end of engine main body, can be in the interference of avoiding front-wheel, make engine main body near front wheel side, the dwindling of wheel base that helps dilly maybe can must be longer with the wheel travel settings of front-wheel.

The described invention of fourth aspect present invention can avoid the angle of valve shaft of suction valve and outlet valve bigger, can reduce the size of cylinder head, in addition, can help to reduce the frictional loss of valve transmission device.

Also have, the described invention of the present invention the 5th and the 6th aspect can be in the interference of avoiding front-wheel, and the anterior cylinder head of engine main body that makes V-arrangement is near front wheel side, avoid the wheel base of dilly elongated, or the wheel stroke of front-wheel situation about shortening, simultaneously, engine main body is arranged at lower position as best one can, can be above engine main body, guarantee bigger space, this space is used to guarantee the space of miscellaneous part, reduces the height of driver with seat.

Description of drawings

Fig. 1 is the side view of motorcycle.

Fig. 2 is the side view that removes part of the Power Component seen from the direction identical with Fig. 1.

Fig. 3 is the sectional view along the 3-3 line among Fig. 2.

Fig. 4 is the sectional view along the 4-4 line among Fig. 3.

Fig. 5 is the view along the 5-5 line among Fig. 4.

Fig. 6 be omitted swing arm state with the corresponding figure of Fig. 5.

Fig. 7 is the sectional view along the 7-7 line among Fig. 5.

Fig. 8 is the sectional view along 88 lines among Fig. 5.

Fig. 9 is the sectional view along the 9-9 line among Fig. 4.

Figure 10 is the sectional view along the 10-10 line among Fig. 4.

The view of Figure 11 for looking along 11 arrows among Fig. 9.

Symbol description: 11 vehicle frames; 12 bent axles; 13 engine main bodies; 16F, the 16R cylinder head; 127 suction valves; 128 outlet valves; 129 air inlet valve springs; 130 exhaust valve springs; 131 camshafts; 134 first swing arms; 135 second swing arms; 142 first cams; 143 second cams; 144 rollers; 146 cam slides; CF, the CR cylinder axis; E-engine; The FB front assembly; The RB rear assembly; The WF front-wheel.

Concrete enforcement

One embodiment of the invention shown in reference to the accompanying drawings describes embodiments of the invention below.

Fig. 1～11 expression one embodiment of the invention, Fig. 1 is the side view of motorcycle, Fig. 2 is the side view that removes part of the Power Component seen from the direction identical with Fig. 1, Fig. 3 is the sectional view along the 3-3 line among Fig. 2, Fig. 4 is the sectional view along the 4-4 line among Fig. 3, Fig. 5 is the view along the 5-5 line among Fig. 4, Fig. 6 be omitted swing arm state with the corresponding figure of Fig. 5, Fig. 7 is the sectional view along the 7-7 line among Fig. 5, Fig. 8 is the sectional view along the 8-8 line among Fig. 5, Fig. 9 is the sectional view along the 9-9 line among Fig. 4, and Figure 10 is the sectional view along the 10-10 line among Fig. 4, the view of Figure 11 for looking along 11 arrows among Fig. 9.

At first in Fig. 1, on the vehicle frame 11 of the motorcycle of dilly, be equipped with and be disposed at Power Component P between front-wheel WF and the trailing wheel WR, this Power Component P by the motor E of 4 circulations, 2 cylinders and be arranged on this motor E and the axletree 18 of trailing wheel WR between transmission device T constitute.

With reference to Fig. 2～Fig. 4, the engine main body 13 of described motor E comprises: crankcase 14, and it is rotatably mounted to have the bent axle 12 of the horizontal axis that extends along the left and right directions of vehicle frame 11; Front assembly FB, it makes cylinder axis CF towards preceding tilting, and is connected setting with described crankcase 14; Rear assembly RB, it sees from the side to be in the shape of the letter V with described cylinder axis CF described cylinder axis CR is tilted towards the back upper place, and is connected setting with described crankcase 14, two assembly FB, RB is respectively the head valve type.

Front assembly FB comprises anterior cylinder block 15F, and itself and described crankcase 14 link; Anterior cylinder head 16F, itself and described anterior cylinder block 15F link; Anterior skull 17F, its with the opposition side of anterior cylinder block 15F, link with anterior cylinder head 16F, rear assembly RB comprises: rear portion cylinder block 15R, itself and 14 bindings of described crankcase; Rear portion cylinder head 16R, itself and rear portion cylinder block 15R link; Rear portion skull 17R, its with the opposition side of rear portion cylinder block 15R, link with rear portion cylinder head 16R.

Crankcase 14 is linked mutually by housing left side 19 and housing right-hand part 20, this housing left side 19 is towards direct of travel the place ahead of motorcycle the time, be disposed at the left side, this housing right-hand part 20 is towards direct of travel the place ahead of motorcycle the time, be disposed at the right side, described two case half 19,20 by with described front and rear assembly FB, the cylinder axis CF of RB, the junction plane 21 that CR is parallel and mutually combining.

One end of bent axle 12 runs through the left hand crankshaft collar 22 that is arranged on the housing left side 19, and it is rotatably mounted by this crankshaft journal portion 22, the other end of bent axle 12 runs through the right hand crankshaft collar 23 that is arranged on the housing right-hand part 20, and rotatably mounted by this crankshaft journal portion 23.

Bent axle 12 comprises: the first crank counterweight portion 24 that is arranged at the inside of left hand crankshaft collar 22, be arranged at the second crank counterweight portion 25 of the inside of right hand crankshaft collar 23, the big end of common bar 28F rotatably is connected with crank pin 29 with the big end of common bar 28R, this common bar 28F be entrenched in the chimeric piston 27F of cylinder thorax 26F that is arranged among the anterior cylinder block 15F slidably and be connected, this common bar 28R is connected with the piston 27R that is entrenched in the cylinder thorax 26R that is arranged among the cylinder block 15R of rear portion slidably, this crank pin 29 is with the first and second crank counterweight portions 24, connect between 25, be arranged on the bent axle 12.

But rear portion cylinder block 15R comes to distolateral and be provided with along the axis of bent axle 12 partially from described cylinder block 15F, described two common bar 28F, the big end of 28R is following, in the first and second crank counterweight portions 24, be connected with crank pin 29 between 25, so that the common bar 28F of anterior cylinder block 15F side is provided with near the described second crank counterweight portion 25, the common bar 28R of rear portion cylinder block 15R side is provided with near the first crank counterweight portion 24.

End at the bent axle of giving prominence to from left hand crankshaft collar 22 12 is equipped with generator 30, and this generator 30 is made of with the stator 32 that is accommodated in this rotor 31 rotor 31 on the end that is fixed in bent axle 12.This generator 30 is covered by the port engine cowling 33 that is connected with the housing left side 19 of crankcase 14, and described stator 32 is fixed on the port engine cowling 33.

Be provided with between left crankshaft journal portion 22 and generator 30 and the bent axle 12 coaxial driven gears that center on 35, this driven gear 35 is connected with the rotor 31 of generator 30 by overrunning clutch 34.In addition, the starter motor 36 with spin axis parallel with bent axle 12 is positioned at front and rear cylinder block 15F so that be supported on the top of crankcase 14, between the 15R.The output shaft of this starter motor 36 is provided with driving pinion 37.On the other hand, between the housing left side 19 and port engine cowling 33 of crankcase 14, be integrally formed first and second intermediate gears 38,39, with the 3rd intermediate gear 40, around the axis parallel with bent axle 12 by rotatably mounted, described driving pinion 37 and first intermediate gear 38 engagements of diameter greater than this driving pinion 37, diameter is less than second intermediate gear 39 and 40 engagements of the 3rd intermediate gear of first intermediate gear 38, and the diameter of the 3rd intermediate gear 40 meshes greater than second intermediate gear 39 and with driven gear 35.

Therefore by when motor E starts, making starter motor 36 work, driving force from starter motor 36 is reduced, it is passed to bent axle 12, in addition, after motor E starting, give starter motor 36 1 sides with the transmission of power of bent axle 12 by the effect of overrunning clutch 34.

The other end at the bent axle of giving prominence to from right hand crankshaft collar 23 12, be fixed with a pair of driving sprocket wheel 44F with being integrally formed, 44R, therein on driving sprocket wheel 44F, be wound with cam chain 46F, it is used to drive the valve transmission device 45R that is arranged on the anterior cylinder head 16F, and on another driving sprocket wheel 46R, reeling is used to drive the valve transmission device 45R that is provided with on exhaust casing head 16R.In addition, the starboard engine cowling 47 of the other end of covering bent axle 12 is connected with the housing right-hand part 20 of crankcase 14.

See Fig. 1 again, the air cleaner 48 that is arranged at the place ahead oblique upper of motor E is installed on the vehicle frame 11, and the fuel tank 49 that is arranged at the top of air cleaner 48 is installed on the vehicle frame 11, forwardly with rear portion cylinder head 16F, the last suction tude 50F that passes through separately of 16R, 50R connects described air cleaner 48.And, to from front and rear cylinder head 16F, the outlet pipe 51F that the gas that 16R discharges leads, 51R commonly is connected with the exhaust silencer 52 on the right side that is arranged at trailing wheel WR.

Power transmitting deice T has: belt-type stepless speed variator 53, and it automatically and infinitely changes from the power of bent axle 12 outputs; Train of reduction gears 54 reduces the output of this circulation speed changer 53; Chain type transmission mechanism 55 is arranged between the axletree 18 of train of reduction gears 54 and trailing wheel WR.

The gearbox casing 56 that this power transmitting deice T is had, by housing main body 57, right side housing 58 and left side housing 59 constitute, this housing main body 57 is integral on the housing left side 19 and housing right-hand part 20 that is arranged at crankcase 14, the front portion is arranged at the right side of the case support 14a that extends in the wings, and extend so that the rear portion is arranged at the left side of trailing wheel WR along front and back, the first half right side that this right side housing 58 covers this housing main body 57 is connected with housing main body 57, the latter half of left side of these left side housing 59 covering shell main bodys 57 is connected with housing main body 57, and the case support 14a of the front portion of housing main body 57 and crankcase 14 links.

Between the first half of housing main body 57 and right side housing 58, be formed with speed changer chamber 60, between the latter half of of housing main body 57 and left side housing 59, be formed with gear chamber 61.

Stepless speed variator 53 is accommodated in the speed changer chamber 60, and it comprises drive pulley axle 62, its with the perpendicular plane of the axis of bent axle 12 in, and dispose on the position at these bent axle 12 spaced apart intervals, it has the axis that parallels with bent axle 12; Driven pulley axle 63, it has the axis parallel with this drive pulley axle 62; Driven pulley 64, it is installed on the drive pulley axle 62; Driven pulley 65, it is installed on the driven pulley axle 63; The vee-belt 66 of circulation shape, it is wound on driven pulley 64 and the driven pulley 65.

Drive pulley axle 62 is arranged at the rear of bent axle 12, one end of this drive pulley axle 62 is located on the distolateral support 67 on the housing left side 19 of crankcase 14 rotatably mounted, the intermediate portion of drive pulley axle 62 is rotatably mounted by the intermediate bearing portion 68 on the housing right-hand part 20 of being located at crankcase 14, and the other end of this drive pulley axle 62 is rotatably mounted by the other end side bearing portion 69 on the right side housing 58 of being located at gearbox casing 56.In addition, intermediate bearing portion 68 is the shape of its part along the formed rotating locus of periphery of the second crank counterweight portion 25 of bent axle 12, is arranged on the housing right-hand part 20 of crankcase 14.

Between bent axle 12 and drive pulley axle 62, be provided with driving gear set 70, this driving gear set 70 is the outside of the first crank counterweight portion 24 and be positioned at the inside of left hand crankshaft collar 22, and the generator 30 that is arranged at the outside of left hand crankshaft collar 22 is arranged at the outside of driving gear set 70.

Described driving gear set 70 is by the driving gear 71 that is fixed on the bent axle 12, constitute with the driven gear 72 that is fixed on the drive pulley axle 62 with driving gear 71 engagements, be rotatably installed on the active belt teeth wheel shaft 62 with the equipment gear 73 relative actuation gears 72 of driving gear 71 engagements, so that suppress the generation of the abnormal sound that the backlash of the engaging piece of driving gear 71 and driven gear 72 causes, between driven gear 72 and equipment gear 73, be provided with to apply and make driven gear 73 and the spring of equipment gear 72 to the elastic force of relative sense of rotation.

In described one distolateral bearing portion 67, offer an end that makes drive pulley axle 62 and rotatably run through wherein bearing hole 74, between the outside of the inner face of this bearing hole 74 and drive pulley axle 62, be folded with ball bearing 75.In addition, bearing hole 76 and described bearing hole 74 coaxial settings that the axle direction intermediate portion of described drive pulley axle 62 is rotatably run through are folded with the sealed member 78 of ball bearing 77 and ring-type between the outside of the inner face of bearing hole 76 and drive pulley axle 62.In addition, in described the other end side bearing portion 69, the other end of drive pulley axle 62 is inserted with the bearing hole 79 at the end, itself and each bearing hole 74,76 coaxially, ball bearing 80 is installed between the outside of the inner face of bearing hole 79 and drive pulley axle 62.

Thus, both sides in driving gear set 70, two support bearing drive pulley axles 62, thus, can alleviate the load of intermediate bearing portion 68, make 68 miniaturizations of intermediate bearing portion as far as possible, make it near the second crank counterweight portion, 25 sides, shorten the front and back length of Power Component P more further, can further shorten wheel base.

Drive pulley 64 is made of movable belt pulley half one 85 of master end fast pulley half one 84 and master end, the other end of drive pulley axle 62 is fixed in this master end fast pulley half one 84, this master end movable belt pulley half one 85 relatively master end fast pulley half one 84 approaching, leave and be supported on slidably on the drive pulley axle 62, this drive pulley axle 62 is arranged at the periphery rotating locus of the first and second crank counterweight portions 24,25 of describing bent axle 12 and sees the position that overlaps with the part of drive pulley 64 from the side.

And, described master end movable belt pulley half one 85 axially drives by belt pulley driving mechanism 86, this belt pulley driving mechanism 86 is arranged at corresponding to being wound with described cam chain 46F, the driving sprocket wheel 44F of 46R, on the 44R along on the axial position of described bent axle 12, between described master end movable belt pulley half one 85 and described intermediate bearing portion 68, be provided with described belt pulley driving mechanism 86.

Between the inner ring of ball bearing 77 and master end fast pulley half one 84 on drive pulley axle 62, sleeve cylindraceous 87 around this drive pulley axle 62 is installed, and the movable belt pulley in this master end half one 85 can be supported on this sleeve 87 slidably at axle direction.

Described belt pulley driving mechanism 86 comprises: screw rod 88, this screw rod 88 form around described sleeve 87 cylindric and are fixed on the housing main body 57 of gearbox casing 56; Nut 89, this nut 89 screws togather with screw rod 88; Driven gear 90, this driven gear 90 is integrally formed in the periphery of nut 89; Driving pinion 92, this driving pinion 92 are arranged on the output shaft of the electric motor 91 (with reference to Fig. 2) on the housing main body 57 that is supported on gearbox casing 56; Reduction gear 93, this reduction gear 93 reduces the rotating power of electric motor 91, and it from driving pinion 92, is passed to driven gear 90, is arranged between driving pinion 92 and the driven gear 90.

If adopt such belt pulley driving mechanism 86, corresponding to the work of electric motor 91, nut 89 is in the axle direction advance and retreat work of drive pulley axle 62.In addition, nut 89 is connected with the movable belt pulley in master end half one 85 by ball bearing 94, and corresponding to the described advance and retreat work of nut 89, the movable belt pulley in master end half one 85 slides at the axle direction of drive pulley axle 62.

Thus, the intermediate portion of seeing the drive pulley axle 62 that is arranged at the position that the part that makes drive pulley 64 overlaps with generator 30 from the side is by intermediate bearing portion 68 rotatably supports that are arranged on the crankcase 14, the part of intermediate bearing portion 68 forms along the shape of the formed rotating locus of periphery of describing first and crank counterweight portion 25 that bent axle 12 had, the master end fast pulley axle 84 of driving on being fixed in drive pulley axle 62 that slide along driven pulley axle 63 constitutes the belt pulley driving mechanism 86 of the movable belt pulley 85 in master end of drive pulley 64, be configured in axle direction and driving sprocket wheel 44F along bent axle 12, the corresponding position of 44R, thus, drive pulley 64 its parts are seen from the side, overlap with generator 30 and near bent axle 12 1 sides, consequently, the front and back length of Power Component P can be shortened, and then wheel base can be shortened.

One end of driven pulley axle 63 rotatably runs through housing main body 57 and protrudes in the gear chamber 61, and ball bearing 95 is installed between housing main body 57 and the driven pulley axle 63.In addition, the other end of driven pulley axle 63 is rotatably supported on the right side housing 58 by ball bearing 96.

Driven pulley 65, constitute by slave end fast pulley half one 97 and the movable belt pulley of slave end half one 98, the position of these slave end fast pulley half 97 axial directions is certain and be rotatably supported on the driven pulley axle 63, the movable belt pulley of this slave end half one 98 slave end fast pulley half one 97 relatively is toward or away from slip and is supported on the relative rotation in slave end fast pulley half one 97, and spring energized towards slave end fast pulley half 97 usefulness.

In slave end fast pulley half one 97, can be provided with guide portion 97a cylindraceous with being integral with the relative rotation, and with driven pulley axle 63 around same axis, the movable belt pulley of slave end half one 98 of right side housing 58 sides from gearbox casing 56 and described slave end fast pulley half 97 subtends is supported slidably by described guide portion 97a.And be fixed between the valve spring storage member 99 and movable half belt pulley 98 of slave end on the end of right side housing 58 sides of described guide portion 97a, be provided with the valve spring 100 that movable half belt pulley 98 of slave end is energized towards slave end fast pulley half 97 sides.

Between the guide portion 97a of described slave end fast pulley half one 97 and driven pulley axle 63, be provided with centrifugal clutch 101, rotate with the number of revolution more than the specified value corresponding to the axis of described slave end fast pulley 97, the rotating power of driven pulley 65 is passed to driven pulley axle 63 around driven pulley axle 63.

Train of reduction gears 54 constitutes the rotating power from an end of described driven pulley axle 63 is passed to output shaft 103 and is accommodated in gear chamber 61 through deceleration limit, jack shaft 102 limit, jack shaft 102 and output shaft 103 are rotatably supported on housing main body 57 and the left side housing 59, and an end of output shaft 103 is outstanding from left side housing 59.

Chain type transmission mechanism 55 constitutes, the chain 107 of circulation shape is wound on driving sprocket wheel 105 and the driven sprocket 106, this driving sprocket wheel 105 is fixed in coaxial and non-rotatably is connected on the live axle 104 of this output shaft 103, this driven sprocket 106 is fixed on the axletree 18 of trailing wheel WR, and this chain type transmission mechanism 55 is accommodated in the chain shell 108 in the left side of being located at trailing wheel WR.

Linking on left side housing 59 has fulcrum 109 cylindraceous, and this fulcrum 109 centers on the protuberance of the relative left side housing 59 in the described output shaft 103, and support swingably by radial bearing 110 front portion of described chain shell 108.And live axle 104 is rotatably supported on the chain shell 107 by ball bearing 111,111.

On the other hand, on the housing main body 57 of gearbox casing 56, can swing axis 112 being arranged by radial bearing 113 turntable supportings, this swing axis 112 is coaxial with described output shaft 103 and live axle 104, be arranged at the right side of trailing wheel WR, the front portion of the arm 114 that extends along front and back is fixed on the described swing axis 112.In addition, axletree 18 rotatably supports of trailing wheel WR are between the rear portion of the rear portion of chain shell 108 and above-mentioned arm 114.

But, because on the driven pulley 65 of belt type continuously variable transmission 53, the movable belt pulley of slave end half one 98, from outside and slave end fast pulley half 97 subtends, relatively slave end fast pulley half one 97 approaching, leave, be the shape of fore outer side, its rear portion projection as the right side housing 58 of the exterior side of gearbox casing 56.That is, in right side housing 58, be formed with the 58a of low level portion, the 58a of this low level portion covers drive pulley 64; The 58b of high position portion, the 58b of this high position portion covers driven pulley 65, in the outer side of the 58a of low level portion projection, is connected with the rear portion of the described low level 58a of portion simultaneously.

Around described drive pulley axle 62, on the described low level 58a of portion, offer a plurality of through holes 115, these a plurality of through holes 115 are communicated with speed changer chamber 60, in master end fast pulley half one 84 in drive pulley 64, a plurality of blade 84a have been integrally formed, these a plurality of blade 84a from described each through hole 115, are attracted to the inside of speed changer chamber 60 with air.That is, fast pulley half one 84 in master end is also as fan.

On the right side of gearbox casing 56 housing 58, the air that covers the low level 58a of portion is installed imports cover 116, air imports path 117 and is formed between air importing cover 116 and the 58a of low level portion, this air imports path 117 and is communicated with described each through hole 115, and the front end side of the described high-order 58b of portion of subtend and opening.

And, the opening end that corresponding described air imports path 117 in the front portion of the high-order 58b of portion is formed with the internal communication of the air exhaust passageway 118 that is circular-arc and speed changer chamber 60, this air exhaust passageway 118 opens wide towards the below at the rear of described air introduction hole 117.

And the rotation of corresponding master end fast pulley half one 84, import path 117 from air and import to air the speed changer chamber 60 through through holes 115, stepless speed variator 53 is cooled off, and cooled air 60 is discharged to the outside of gearbox casing 56 through air exhaust passageways 118 from the speed changer chamber.

In crankcase 14, by being arranged at the next door 14b in the crankcase 14, and form crankshaft room 124 and oily reservoir chamber 125 mutually separatedly, the major part of bent axle 12 and an end of drive pulley axle 62 are taken in by this crankshaft room 124; This oil storeroom 125 is arranged at the rear side of bent axle 12, and described oily storeroom 125 extends the inside that also is connected in port engine cowling 33 in the left side of drive pulley axle 62.

And the oil in the described oily storeroom 125 supply to the lubricated portion of each of motor E by not shown delivery valve, and after lubricated, the oil of inside that turns back to crankshaft room 124 turns back to oily storeroom 125 by the not shown valve that returns.

In Fig. 5～Fig. 9, forwardly on the anterior cylinder head 16F of assembly FB, opposed with the top of piston 27F, control is from outlet pipe 50F sucking-off, a pair of suction valve 127 to the gas of the firing chamber 126 that forms between cylinder block 15F forwardly and anterior cylinder head 16F, also can be provided with along arranged side by side on the axial direction of bent axle 12 with opening and closing, control simultaneously from a pair of outlet valve 128 of described firing chamber 126 to the exhaust of outlet pipe 51F, it is parallel with described suction valve 127 places side by side and opens and closes configuration freely, two suction valves 127 are energized to closing the valve direction by the suction side valve spring 129 that is installed in the middle coiled type of anterior cylinder head 16F, and two outlet valves 128 are energized to closing the valve direction by the exhaust side valve spring 130 that is installed in the middle coiled type of anterior cylinder head 16F.

The valve transmission device 45F of described two suction valves 127 of driven for opening and closing and two outlet valves 128 is accommodated among the valve cage 123F that is formed between anterior cylinder head 16F and the anterior skull 17F, this valve transmission device 45F comprises camshaft 131, and this camshaft 131 reduces 1/2 rotating power by synchronous transfer unit 43F through bent axle 12 and rotates driving, is rotatably supported on the anterior cylinder head 16F; First and second swing axiss 132,133, the axis of this first and second swing axis 132,133 and this camshaft 131 are parallel and be supported on the anterior cylinder head 16F; First and second swing arms 134,135, this first and second swing arm 134,135 is supported swingably by first and second balance staffs 132,133.

Described camshaft 131 its axis basic setups are being rotatably supported on the anterior cylinder head 16F between air inlet side valve spring 129 and the exhaust side valve spring 130 on cylinder axis CF.Forwardly on the cylinder head 16F, turning up the soil at interval to be integral along the axle direction of camshaft 131 is provided with a plurality ofly, and for example, pair of support parts 136,137 offers the bearing hole 138,139 that is used for rotatably mounted camshaft 131 on these supports 136,137.And, be folded with ball bearing 140 between the inner face of the bearing hole 138 in support 136 and the periphery of camshaft 131, be folded with ball bearing 141 between the inner face of the bearing hole 139 in support 137 and the periphery of camshaft 131.

At described two supports 136, between 137 on camshaft 131, be integral and be provided with first cam 142 and second cam 143, in these first cam, 142 driving suction valves 127 and the outlet valve 128 one of them is suction valve 127 at present embodiment, this second cam 143 be used for driving suction valve 127 and outlet valve 128 another, be suction valve 128 at present embodiment.And, second cam 143 forms less than first cam, 142 ground, along the direction of the axis of camshaft 131 air inlet side and exhaust side valve spring 129 arranged side by side respectively, the air inlet side and the exhaust side valve spring 129 of axle direction one side (left side of Fig. 5 and Fig. 6) in 130, between 130, first cam 142 is arranged at than the air inlet side of a described axial wherein side and exhaust side valve spring 129,130, further along position that a described axial wherein side staggers.

First and second swing axiss 132,133 are supported on the anterior cylinder head 16F from the position that is positioned at clamp cam axle 131 up and down when the direction of cylinder axis CF is seen, and second swing axis 133 is arranged at the below of first swing axis 132.In addition, be set at distance between second swing axis 133 and the bent axle 12 less than the distance between first swing axis 132 and the bent axle 12.That is, second swing axis 133 distance of comparing Δ L with first swing axis 132 is arranged at the position near bent axle 12.

On first swing axis 132, be supported with first swing arm 134 swingably, this first swing arm 134 has the contact arm 134a that contacts with a pair of suction valve 127 respectively, 134b, in this first swing arm 134, the roller 144 that contacts with first cam, 142 rollings of camshaft 131 is by roller bearing 145 supportings.In addition on second swing axis 134, be supported with second swing arm 135 swingably, this second swing arm 135 has the contact arm 135a that contacts with a pair of outlet valve 128 respectively, 135b, and this second swing arm 135 is provided with second cam, the 143 sliding contact cam slides 146 with camshaft 131.

Synchronous transmission device 43F is accommodated among the 148F of cam chain chamber, this cam chain chamber 148F from crankcase 14 across anterior cylinder block 15F, anterior cylinder head 16F and anterior skull 17F, it comprises the driving sprocket wheel 44F that is fixed on the bent axle 12, be arranged on the driven sprocket 149F on the end of the outstanding camshaft 131 of support part 136 from described cylinder head 16F, be wound in the cam chain 46F on driving sprocket wheel 44F and the driven sprocket 149F, the slack-side of this cam chain 46F is given and chain tensioning device 150F certain force of strain and that contact with cam chain 46F slidably, vertical intermediate portion of pushing this chain tensioning device 150F with certain load is installed on the known tensioning push rod 151F on the anterior cylinder block 15F, this tensioning push rod 151F, with the advancing side sliding contact of cam chain 46F, be installed on the chain guide 152F on the anterior cylinder block 15F.

But, bent axle 12 rotates along the direction shown in the arrow 153 of Fig. 4, because at synchronous transmission device 43F cam chain 46F, be arranged at the front side of cylinder axis CF, promptly, cylinder axis CF is towards preceding tilting, so the bottom side of cylinder axis CF constitutes slack-side, chain tensioning device 150F and tensioning push rod 151F all are arranged at the front side of cylinder axis CF.

Described driven sprocket 149F is by a plurality of, and for example, pair of bolts 155,155 is fixed on the support unit 154, and this support unit 154 waits on the end that is fixed among the anterior cylinder head 16F camshaft 131 that support 136 relatively gives prominence to by being pressed into.

In Figure 10, the valve transmission device 45R of rear assembly RB side is accommodated among the valve cage 123R, this valve cage 123R is formed between rear portion cylinder head 16R and the rear portion skull 17R, this valve transmission device 45R comprises camshaft 131, and this camshaft 131 rotates to drive and is rotatably supported on the cylinder head 16R of rear portion by reducing 1/2 rotating power by synchronous transmission device 43R through bent axle 12; Have the parallel axis of described camshaft 131 and be supported on first and second swing axiss 132,133 on the cylinder head 16R of rear portion; By first and second swing arms 134,135 of supporting swingably respectively of first and second swing axiss 132,133, this valve transmission device 45R constitutes identical with the valve transmission device 45F of front assembly FB side.

And in the structure of valve transmission device 45R, adopt prosign with the corresponding part of the valve transmission device 45F of front assembly FB side, only provide diagram, and omit specific description.

Pay special attention to Fig. 4, synchronous transmission device 43R is accommodated among the 148R of cam chain chamber, across between rear portion cylinder block 15R, rear portion cylinder head 16R and the rear portion skull 17R, it comprises driving sprocket wheel 44R to this cam chain chamber 148F from crankcase 14, and this driving sprocket wheel 44R is fixed on the bent axle 12; Driven sprocket 149R, this driven sprocket 149R are fixed on the end of camshaft 131; Cam chain 46R, this cam chain 46R are wound on driving sprocket wheel 44R and the driven sprocket 149R; Arc chain tensioning device 150R, this chain tensioning device 150R gives certain force of strain to the slack-side of this cam chain 46R and contacts with cam chain 46R slidably; Known tensioning push rod 151R, this tensioning push rod 151R pushes vertical intermediate portion of this chain tensioning device 150R with certain load, and is installed on the anterior cylinder block 15R; Chain guide 152R, this chain guide 152R slides at the advancing side of cam chain 46R, is installed on the cylinder block 15R of rear portion.

And follow the rotation of bent axle 12 along the direction shown in the arrow 153, the cam chain 46R of synchronous transmission device 43R, the front side of the cylinder axis CR of rear assembly RB is a slack-side, and chain tensioning device 150R and tensioning push rod 151R are arranged at the place ahead of the cylinder axis CR that tilts towards the back upper place.

Described driven sprocket 149R for example passes through, pair of bolts 157,157 and be fixed in fixing pulsation cam 156 by an end that is pressed into camshaft 131, on pulsation cam 156, along its circumferential isolated 3 positions, be equipped with along the radial direction teat 156a outstanding, on the cylinder head 16R of rear portion, be equipped with by detecting the compression top dead center detecting sensor 158 that described each teat 156a detects the compression top dead center of piston 27R towards the outside.

But, the cylinder of detection reference when the detection of compression top dead center, detect the compression top dead center of rear assembly RB in the present embodiment, by not shown crankshaft angle sensor, in the present embodiment by judging the phase place of front assembly FB, thus, can detect the compression top dead center of the front assembly FB of other cylinders, only have under the situation of single teat at the pulsation cam, when because of the noise signal confusion, can not judge the compression top dead center of 1 circle of camshaft 131.Therefore, as mentioned above, 3 teats 156 are arranged on the pulsation cam 156, thus, even sneaking under the situation of noise, still can recover by the half-turn (1 circle of bent axle 12) of camshaft 131.

Forwardly among assembly FB and the rear assembly RB, at cylinder head 16F, being separately installed with spark plug 158 on the 16R makes it anterior in the face of firing chamber 126, between suction valve 127 and outlet valve 128, be provided with bent axle 131, comprising cylinder axis CF, CR, and on the projection drawing on the plane (plane shown in Figure 9) of the parallel axes of camshaft 131, spark plug 158 is installed on cylinder head 16F from the inclination side, 16R, its axis and driven sprocket 149F, the angled intersection of elongation line of the axis of the camshaft 131 of 149R opposition side.

Promptly, with regard to cylinder axis CF, CR with cam chain chamber 148F, the opposition side of 148R is near cylinder head 16F, the skull 17F of 16R, the outer side surface of 17R, be provided with in the installation of private side depression and use recess 159 so that spark plug 158 is installed, with firing chamber 126 subtends be arranged at cylinder head 16F, in the mounting hole 160 on the 16R, be screwed into spark plug 158 with recess 159 from described installation.

In the mounting structure of thus spark plug 158, must prevent to be used for spark plug 158 is installed on cylinder head 16F, instrument on the 16R, countercylinder head 16F, 16R and skull 17F, the joint of 17R causes the situation of interference, from then on viewpoint should connect skull 17F, and 17R is arranged at cylinder head 16F, skull junction surface 161F on the 16R, 161R forms and cylinder axis CF, the plane oblique that CR is vertical so that along the axis of camshaft 131 towards described driven sprocket 149F, 149R and dwindle cylinder block 15F, the distance between the 15R.

But, be integral have first and second cams 142,143 camshaft 131 at the ball bearing 140 that is equipped with between support 136,137,141 state, the outer ring of described ball bearing 140,141 is pressed into the bearing hole 138 of support 136,137, in 139, with the opposition side of described spark plug 158, at described cylinder head 16F, on the sidewall of 16R, as shown in figure 11, two ends and described skull junction surface 161F, 161R connects, and is provided with semicircular recess 162F, 162R, this recess can make this camshaft 131 run through when camshaft 131 being installed in described each bearing hole 138,139.

And, be and described skull junction surface 161F, between the 161R, be folded with gasket seal 164, with cylinder head 16F, the skull 17F that 16R connects is on the 17R, be integral the cap 163 that is provided with semicircle shape, the cap 163 of this semicircle shape is corresponding to described skull 17F, 17R and described cylinder head 16F, the situation that 16R connects, with described recess 162F, the 162R sealing.

But, camshaft 131 is being installed on support 136,137 bearing hole 138, in the time of on 139, described bearing hole 138 is not pure circle, its part is the shape that expands towards the outside so that can run through the high-order portion of first cam 142, so that the first bigger cam 142 in first and second cams 142,143 that camshaft 131 is had runs through the bearing hole 138 of support 136.

Effect to present embodiment describes below, front and rear assembly FB in the motor E of V-arrangement, the valve transmission device 45F of RB, among the 45R, be respectively arranged with first and second cams 142, camshaft 131 its axis basic setups of 143 are in cylinder axis CF, CR is last and be supported on cylinder head 16F, on the 16R, second cam 143 that is arranged between air inlet side and the exhaust side valve spring 129,130 is arranged at along the direction of the axis of camshaft 131 less than first cam, 142, the first cams 142, with the position of staggering between air inlet side and the exhaust side valve spring 129,130.

Therefore, can avoid first and second cams 142,143, with air inlet side and exhaust side valve spring 129, interference between 130 simultaneously, set the angle of the valve rod of suction valve 127 and outlet valve 128 less, can reduce the overall dimensions of firing chamber 126, obtain higher compression ratio, and can realize having the valve transmission device 45F of camshaft 131, the overall dimensions of 45R reduces, and then reduces cylinder head 16F, the size of 16R.

And, both sides at camshaft 131, direction a pair of respectively suction valve 127 and outlet valve 128 arranged side by side along the axis of this camshaft 131 can be arranged at front and rear assembly FR with opening and closing, cylinder head 16F among the RB, on the 16R, thus, in the overhead cam h type engine h of 4 valves, can realize firing chamber 126 overall dimensions reduce to obtain higher compression ratio, and can realize having the valve transmission device 45F of camshaft 131, the overall dimensions of 45R reduces, and then reduces cylinder head 16F, the size of 16R.

Also have, be in the posture of level at axis with bent axle 12, rear at the front-wheel WF of motorcycle, be installed on the front assembly FB of the engine main body 13 on the vehicle frame 11, first swing arm 134 that is driven in first cam 142 is supported swingably by first swing axis 132 with axis parallel with cam 131, second swing arm 135 that is driven in second cam 143 is supported swingably by second swing axis 133, this second swing axis 133 has the axis parallel with camshaft 131, and being arranged at the below of first swing axis 132, the distance between second swing axis 133 and the bent axle 12 is less than the distance between first swing axis 132 and the bent axle 12.

Thus, forwardly among the assembly FB, even cylinder axis CF tilts towards the place ahead, can shorten bent axle 12 as best one can to the distance between the front bottom end of motor 13, can be in the interference of avoiding front-wheel WF, make engine main body 13 near front-wheel WF side, can help the dwindling of wheel base of motorcycle, maybe can must be longer with the wheel travel settings of front-wheel WF.

Also have, motor E is a V-arrangement, can be in the interference of avoiding front-wheel WF, make anterior cylinder head 16F near front-wheel WF side, as best one can engine main body 13 is provided with lower position, can above motor overall 13, guarantees that the space is bigger, to be used for another parts, can reduce the height of driver with seat.

Have again, because in first swing arm 134, roller 144 by the 142 rolling contacts of axle Zhi Youyu first cam, in second swing arm 135, be provided with cam slide 146 with 143 sliding contacts of second cam, the less cam slide in space 146 be can avoid being provided with and air inlet side and exhaust side valve spring 129 are being arranged at, realize sliding contact on second cam 143 between 130, the situation that the angle of the valve shaft of suction valve 127 and outlet valve 128 increases reduces cylinder head 16F, the size of 16R, in addition, because of be arranged at air inlet side and exhaust side valve spring 129,130 between the position of staggering, and on first cam 142 that described angle is not impacted, the bigger roller in space 144 is set realizes the contact of rolling, thus, can help valve transmission device 45F, the reduction of the frictional loss of 45R.

In addition, on the rear assembly RB that cylinder axis CR is tilted, between bent axle 12 and camshaft 131, setting has the synchronous transmission device 43R of chain tensioning device 150R, the power of bent axle 12 is reduced, its gearbox casing 56 that is delivered to the speed changer 53 on the trailing wheel WR is extended to the rear from crankcase 14, but described chain tensioning device 150R is arranged at the place ahead of described cylinder axis CR.

Therefore, setting by chain tensioning device 150R, rear portion cylinder block 15R does not heave towards rear side, the angle of inclination towards rear side of described cylinder axis CR is bigger, even in this case, still can avoid the capacity of gearbox casing 56 to diminish, can avoid the interference of rear portion cylinder block 15R simultaneously, can reduce the height of motor E gearbox casing 56.

And motor E constitutes: front assembly FB, and this front assembly FB makes cylinder axis CF towards preceding tilting; Rear assembly RB, this rear assembly RB makes cylinder axis CR tilt towards the back upper place, and the motor E that can make V-arrangement side in the wings reduces the height of motor E to tilt largely.

Also have, the sidewall of the anterior cylinder head 16F that had of assembly FB bottom forwardly, and on the sidewall rear portion of the rear portion cylinder head 16R that had of rear assembly RB, be connected with outlet pipe 51F respectively, 51R can be the space that rear side produces with the below of the front assembly FB among the motor E of the V-arrangement that tilts largely, can fetch the outlet pipe 51F of front assembly FB well, suppress outlet pipe 51F from Power Component P, outstanding towards the below, guarantee minimum ground height easily.In addition, because in rear assembly RB, the parts relevant with chain tensioning device 150R, that is, tensioning push rod 151R is not from rear assembly RB, and is rearward outstanding, so can under the situation of not considering to avoid to the interference of these parts, easily arrange the outlet pipe 151R of rear assembly RB.

But, forwardly with rear assembly FB, among the RB, at described valve transmission device 45F, on one end of the camshaft 131 among the 45R, be fixed with driven sprocket 149F, 149R, forwardly with rear portion cylinder head 16F, on the 16R, spark plug 158 is installed, the axis of this spark plug 158 with and driven sprocket 149F, the elongation line of the axis of the camshaft 131 of the opposition side of 149R intersects angledly, should connect skull 17F, 17R's, be arranged at each cylinder head 16F, skull junction surface 161F on the 16R, 161R constitutes the plane of inclination, and this plane of inclination is following, with each cylinder axis CF, the perpendicular plane inclination ground of CR intersects, should for: be driven in along the axis of camshaft 131, towards described driven sprocket 149F, the motion of 149R side, cylinder block 15F, the distance between the 15R diminishes.

If thus, skull junction surface 161F, 161R is driven in along the axis of camshaft 131, towards described driven sprocket 149F, the motion of 149R side, near cylinder block 15F, the inclination of 15R, then with spark plug 158 corresponding parts, described skull junction surface 161F, 161R is positioned at apart from cylinder block 15F, 15R position farthest.Therefore, even under the situation that the mounting position with spark plug 158 with the intermediate portion subtend of firing chamber 126 lifts, still can avoid cylinder head 16F, the size of 16R increases, and skull 17F, and the rigidity that the size of 17R reduces to cause reduces, can avoid simultaneously spark plug instrument countercylinder head 16F, 16R and skull 17F, the interference of the joint of 17R also can increase the installation degrees of freedom of spark plug 158.

And, forwardly with rear portion cylinder head 16F, on the 16R, be integral and be provided with pair of support parts 136,137, this pair of support parts 136,137 have the bearing hole 138 of rotatably mounted camshaft 131 respectively, 139, with the opposition side of spark plug 158, at cylinder head 16F, on the sidewall of 16R, the recess 162F of semicircle shape, 162R connect the described skull junction surface 161F that is arranged at two ends, on the 161R, described camshaft 131 is being installed on each bearing hole 138, in the time of in 139, this recess 162F, 162R can make described camshaft 131 run through.

Thus, at skull 17F, on the 17R, be provided with semicircular cap 163, this cap 163 is corresponding to this skull 17F, 17R and cylinder head 16F, the situation that 16R connects, with described recess 162F, the 162R sealing, in order to seal recess 162F, 16R need not skull 17F, parts beyond the 17R, by recess 162F is set, 162R can prevent the situation that number of components increases.

In the above, embodiments of the invention are illustrated, still, the invention is not restricted to described embodiment, can carry out various design alterations not breaking away under the situation of the present invention that the claim scope put down in writing.

For example, the present invention also can be used for the dilly of the motor tricycle etc. beyond the motorcycle.

Claims

1. overhead cam h type engine h, it is at the cylinder head (16F of a part that constitutes engine main body (13), 16R), can be provided with suction valve (127) and outlet valve (128) with opening and closing, this suction valve (127) and outlet valve (128) are by spiral helicine air inlet side and exhaust side valve spring (129,130), energized towards closing the valve direction, be rotatably supported in described cylinder head (16F being arranged between described suction valve side valve spring (129) and the exhaust valve side valve spring (130), on the camshaft 16R) (131), be provided with first cam (142) and second cam (143), this first cam (142) is used for driving (128) one of suction valve (127) and outlet valves, this second cam (143) be used for driving suction valve (127) and outlet valve (128) another, it is characterized in that, its axis of described camshaft (131) is disposed at cylinder axis (CF basically, CR) on, and be supported on described cylinder head (16F, 16R), be arranged at air inlet side and exhaust side valve spring (129,130) second cam (142) between is less than first cam (142), first cam (142) is arranged at along the direction of the axis of described camshaft (131), the position of staggering between described relatively air inlet side and the exhaust side valve spring (129,130).

2. overhead cam h type engine h according to claim 1, it is characterized in that, both sides in described camshaft (131), along the direction of the axis of this camshaft (131) a pair of suction valve (127) arranged side by side and outlet valve (128) can be arranged at with opening and closing described cylinder head (16F, 16R) on.

3. overhead cam h type engine h according to claim 1 and 2, it is characterized in that, the engine main body (13) that comprises described cylinder head (16F) with described cylinder axis (CF) towards preceding tilting, and the axis of bent axle (12) is in the posture of level, rear at the front-wheel (WF) of dilly, be installed on the vehicle frame (11), be driven in described first and second cams (142, first swing arm (134) of a motion 143) is supported on its axis first swing axis (132) parallel with described camshaft (131) swingably, be driven in described first and second cams (142, second swing arm (135) of another motion 143) is supported on its axis second swing axis (133) parallel with described camshaft (131) swingably, this second swing axis (133) is arranged at the rear of first swing axis (132), and the distance between second swing arm (133) and the bent axle (12) is less than the distance between first swing axis (132) and the bent axle (12).

4. overhead cam h type engine h according to claim 3, it is characterized in that, in described first swing arm (134), roller (144) by axle Zhi Youyu first cam (142) rolling contact, in described second swing arm (135), be provided with cam slide (146) with described second cam (143) sliding contact.

5. overhead cam h type engine h according to claim 3, it is characterized in that, described engine main body (13) is V-shaped, it comprises towards the front assembly of the cylinder axis that preceding tilts (CF) (FB), with the rear assembly (RB) of seeing the cylinder axis (CR) that V-shaped and described cylinder axis (CF) intersects from the side.

6. overhead cam h type engine h according to claim 4, it is characterized in that, described engine main body (13) is V-shaped, it comprises towards the front assembly of the cylinder axis that preceding tilts (CF) (FB), with the rear assembly (RB) of seeing the cylinder axis (CR) that V-shaped and described cylinder axis (CF) intersects from the side.