CN102003263B - Cooling device of a power unit - Google Patents

Abstract

The invention provides a cooling device of a power unit, capable of preventing an oil cooler from projecting. The cooling device comprises an oil cooler (105) and the oil cooler comprises: an oil path (108) for the oil supplied to an engine (20) as the power unit; a cooler cooling mechanism (109) for cooling the oil through the oil path (108), wherein the oil cooler (105) extends upwards along the axle of the cylinder (L1) and is formed into the plate shape at the side of the cylinder (22A).

Description

The cooling unit of power unit

Technical field

The present invention relates to the cooling unit of power unit.

Background technique

Patent Document 1 discloses a kind of structure, namely be equipped on the power unit (also referred to as motor) on two-wheeled motorcycle etc., cylindric oil cooler (for example, referring to patent documentation 1) is configured below the cylinder of power unit.

Patent documentation 1: Japanese Unexamined Patent Publication 2003-314277 publication

But, because structure is in the past the oil cooler of the circumferential arrangement cylindrical shape at cylinder side wall, so oil cooler is outstanding and volume large, cause power unit to maximize.In addition, owing to being configured with oil cooler in crankcase bottom, so the distance of food tray and oil cooler becomes near, the impact of the oil temperature that oil cooler is subject in food tray causes temperature to rise.

Summary of the invention

The present invention is the invention made in view of the foregoing, its object is to the cooling unit providing a kind of power unit, can suppress the outstanding of oil cooler.

In order to solve above-mentioned problem, the cooling unit of power unit of the present invention, this power unit has crankcase and cylinder, described cylinder has the cylinder cooling mechanism of the cylinder sleeve that slidably can keep piston and the periphery covering this cylinder sleeve, it is characterized in that, there is oil cooler, this oil cooler has the oil circuit passed through for the oil being fed into described power unit, the cooler cooling mechanism cooled the oil by this oil circuit, this oil cooler extends on cylinder axis direction, and is formed as the tabular of the side being positioned at described cylinder.

In said structure, described cylinder can by with the clamping bolt of more than configure roughly at equal intervals three and described crankcase fastened integratedly, described cylinder cooling mechanism is formed as the roughly planar extended along the cylinder axis direction linked with roughly straight line between described clamping bolt, and described oil cooler extends at spaced intervals along the plane of described cylinder cooling mechanism.

In addition, in said structure, described power unit, has cylinder in the front being bearing in the bent axle on crankcase, has mission case at crankshaft end, below bent axle, have food tray, and described oil cooler is configured in the top of described food tray.

Can also be that described mission case collecting V belt-type transmission, described oil cooler is located at the front upper place of described mission case in said structure.

In addition, in said structure, can also have oil pump, this oil pump picks up the oil of described food tray, and by oil to each several part supply comprising crankshaft lubrication portion, described oil cooler is configured in described oil pump and between the described crankshaft lubrication portion in its downstream.

In said structure, cylinder head lubricating oil path can also be had, this cylinder head lubricating oil path between described oil pump and described oil cooler via throttle orifice branch, and by oil to be arranged on described cylinder cylinder head supply.

In addition, in said structure, piston nozzle can also be had, this piston nozzle between described oil pump and described oil cooler via throttle orifice branch, and oil to be sprayed to the piston that is free to slide in described cylinder.

In addition, in said structure, at the inner space cooling air of described mission case by suction and discharge, described oil cooler is integrally formed on described mission case.

In addition, in said structure, can also be, described cylinder configures frontward relative to bent axle level, and have cap assembly in described bent axle side, described oil cooler is configured on the end difference between described cylinder and described cap assembly.

In addition, in said structure, can also be, described oil cooler be located on described cap assembly, and the side of the side of cylinder side and the opposition side of cylinder has the cooling fan as described cooler cooling mechanism.

The effect of invention

In the present invention, oil cooler extends on cylinder axis direction, and is formed as the tabular of the side being positioned at cylinder, therefore, it is possible to along cylinder side wall configuration oil cooler, can suppress the outstanding of oil cooler.

In addition, cylinder by with the clamping bolt of more than configure roughly at equal intervals three and crankcase fastening integratedly, cylinder cooling mechanism is formed as the roughly planar along extending with the cylinder axis direction roughly between straight line link clamping bolt, as long as oil cooler extends at spaced intervals along the plane of cylinder cooling mechanism, just oil cooler can be configured close to cylinder, even if its outstanding from motor also can be suppressed for large-scale oil cooler.

In addition, the front that power unit is being supported in the bent axle on crankcase has cylinder; At crankshaft end, there is mission case; Below bent axle, there is food tray, as long as oil cooler is configured in the top of food tray, in the front of bent axle, there is cylinder, crankshaft end has mission case, have in the motor of food tray below bent axle, just oil cooler can be configured away from food tray thus the cooling effectiveness of oil cooler is improved, the miniaturization of oil cooler can be realized.

In addition, mission case collecting V belt-type transmission, as long as oil cooler is arranged on the front upper place of mission case, just can form oil cooler on the box part that inside is dry space, and oil cooler configures away from food tray, the cooling effectiveness of oil cooler can be improved further.

In addition, there is oil pump, this oil pump picks up the oil of food tray, and to comprising each several part in crankshaft lubrication portion for oil supply, as long as oil cooler is configured in oil pump and between the crankshaft lubrication portion in its downstream, just can by the oil that cooled by oil cooler to the supply of crankshaft lubrication portion, even if be the motor that the thermal diffusivity of crankshaft room is not too good, the cooling of crankshaft room also can be carried out well.

In addition, as long as have cylinder head lubricating oil path, this cylinder head lubricating oil path between oil pump and oil cooler via throttle orifice branch, and to the cylinder head be arranged on cylinder for oil supply, then just can carry out the lubrication in cylinder head lubrication portion etc. and the cooling based on oil well without the need to the supply oil circuit lengthened to cylinder head, and the oil-break in cylinder head lubrication portion can be prevented.

In addition, as long as have piston nozzle, this piston nozzle between oil pump and oil cooler via throttle orifice branch, and spray oil to the piston that is free to slide in cylinder, just can guarantee the oil pressure of piston nozzle.

In addition, in the inner space of mission case, cooling air is by suction and discharge, as long as oil cooler is integrally formed on mission case, cooling effect based on internal cooling wind just can act on oil cooler via mission case, improves the cooling effectiveness of oil cooler.

In addition; cylinder configures relative to the horizontal forward direction of bent axle, has cap assembly in bent axle side, and oil cooler is configured on the end difference between cylinder and cap assembly; the maximization of motor can either be avoided like this, maximization and the protection of oil cooler can be realized again simultaneously.

In addition, oil cooler is located on above-mentioned cap assembly, as cooler cooling mechanism, has cooling fan in the side of the side of cylinder side and the opposition side of cylinder, can improve cooling effectiveness by increasing heat radiation area like this.

Accompanying drawing explanation

Fig. 1 is the side view of the two-wheeled motorcycle of embodiments of the present invention.

Fig. 2 is the in-built figure representing motor on the right side of vehicle body.

Fig. 3 is the figure in the III-III cross section representing Fig. 2.

Fig. 4 is the figure representing peripheral structure and crankcase and cylinder part on the right side of vehicle body together.

Fig. 5 (A) is the figure of the superstructure representing motor, Fig. 5 (B) is the figure representing left and right cross-sectional configuration.

Fig. 6 is the side view observing mission case on the right side of vehicle body.

Fig. 7 is the side view from vehicle body left sides mission case.

Fig. 8 (A) is the figure that (table side) represents oil cooler cover on the right side of vehicle body, Fig. 8 (B) schemes seen by vehicle body rear, Fig. 8 (C) is (inboard) seen figure on the left of vehicle body, and Fig. 8 (D) is the figure in the D-D cross section representing Fig. 8 (A).

Fig. 9 is the figure representing oil lubrication system.

Figure 10 is the figure of the lubricating structure representing crankshaft lubrication portion.

The explanation of reference character

1 two-wheeled motorcycle

2 vehicle body frames

20 motors (power unit)

22 cylinder part

22A cylinder block

22F, 106A, 109 cooling fans

24 crankcases

51 bent axles

51R rotating band wheel shaft (live axle)

60 V variable v-belt drives

61 speed changer accommodation sections

61A mission case (cap assembly)

61B speed changer cover (cap assembly)

64 driven belt wheel shafts (driven shaft)

68 V bands

80 starting clutches (Wetting centrifugal clutch)

97 torsional damper

105 oil coolers

106 oil cooler main bodys

107 oil cooler covers

120 oil pumps

L1 cylinder axis

Embodiment

Below, with reference to accompanying drawing, an embodiment of the invention are described.

In addition, in the following description, about all around and the record in upper and lower direction as without special records with in vehicle towards identical.In addition, in figure, arrow F represents vehicle front, and arrow R represents vehicle body right, and arrow U represents above vehicle body.

Fig. 1 is the side view representing the two-wheeled motorcycle 1 being suitable for embodiments of the present invention.

The vehicle body frame 2 of this two-wheeled motorcycle 1 has: the head tube 3 of body forward structure; Rearward tiltedly to have a down dip the main car frame 4 tiltedly extended from this head tube 3; Extend downwards and be fixed on the pairing left and right pivot cradle 5 at the rear portion of this main car frame 4; Pairing left and right seat rail 6, it rearward tiltedly to extend and at bent halfway until rear end from the front adjacent of the fixed position of pivot cradle 5 at the rear portion of main car frame 4; To the pairing left and right strengthening frame 7 reinforced between pivot cradle 5 and the central part of above-mentioned seat rail 6.

Be provided with above the pairing left and right seat rail 6 of vehicle body frame 2 and take advantage of auto use chair 8, be provided with container (containing box) 9 in its underpart.Above body forward structure, be provided with the handle 10 be bearing in by axle in head tube 3, be thereunder extended with front fork 11,11 and be supported with front-wheel 12 at its lower end axle.Rocking arm (also referred to as back vent) 14 to be bearing in the mode axle enabling front end swing in the pivot cradle 5 of vehicle body central authorities via pivot 13 and rearward to extend, and is supported with trailing wheel 15 at the rearward end axle of rocking arm 14.Between the rear portion of rocking arm 14 and seat rail 6, folder is inserted with pairing left and right rear shock absorber 16.

In the below of main car frame 4 and the front of pivot cradle 5, suspension has as internal-combustion engine and motor (also referred to as power unit) 20.The top of motor 20 is hung to be located on supporting bracket 17, and this supporting bracket 17 hangs down and is located at the central part of main car frame 4, and the rear portion of motor 20 is fixed on two positions in pivot cradle 5.That is, motor 20 is supported on the downside of the rear portion of main car frame 4 with the state of suspention.In addition, vehicle body frame 2 is covered by the plastic body shell 18 being divided into each several part.

Motor 20 is four-stroke air-cooled engines of single-cylinder, be configured to the front surface of cylinder part 22 from crankcase 24 with the horizontal engine significantly leaned forward close to approximate horizontal state, cylinder part 22 is configured to horizontal forward relative to the bent axle 51 be bearing in by axle on crankcase 24.Therefore, while can making vehicle body centre of gravity, the portion that the straddles M that when can also reduce main car frame 4 as illustrated thus can reduce by bus, driver straddles, improves lowering resistance.In addition, in the left surface front portion of crankcase 24, generator cover 25 is installed.As shown in Figure 1, body shell 18 from vehicle body side observe have cover vehicle body until crankcase 24 outer rim near hood-shaped shape, crankcase 24 side comprising generator cover is externally exposed.

On the upside of the cylinder part 22 of this motor 20, be connected with suction tude 26, this suction tude 26 extends upward and is connected to and is supported on throttle valve body 27 on main car frame 4 and air cleaner 28.Outlet pipe 29 is connected with on the downside of cylinder part 22, bending and rearward extend after this outlet pipe 29 extends downwards, and be connected on the baffler 30 that is configured on the right side of trailing wheel 15.

In addition, the output shaft 31 of motor 20 is bearing in the left surface rear portion of crankcase 24 with the mode axle making its front end and expose.Output sprocket (also referred to as driving sprocket wheel) 32 is installed in the front end of this output shaft 31, this output sprocket 32 and and the driven sprocket 33 that is wholely set of trailing wheel 15 between be wound with Transmitted chains 34 (with reference to Fig. 1) thus form chain drive.

That is, this two-wheeled motorcycle 1 is configured to chain driving vehicle, and the rotation of the output shaft 31 of this motor 20 is transmitted to trailing wheel 15 via chain drive.In addition, this chain drive plays a role as the secondary speed-reducing mechanism of the reduction speed ratio set according to the gear ratio of each sprocket wheel 32,33 between output shaft 31 and rear-wheel spindle (secondary speed-reducing ratio).In addition, in figure, reference character 35 represents the cover covering chain drive.

The treadle 36 that vehicle body left and right directions extends is installed in crankcase 24 bottom, at these treadle 36 two ends, pair of pedals 36A, the 36A that driver puts pin is installed.In addition, in Fig. 2, reference character 36B is located at the bottom of crankcase 24 and the locking lug boss having treadle 36 of screw thread.

In addition, on this two-wheeled motorcycle 1, form pilot engine 20 the pedal part (starting system parts) 37 of a part of kick-type starter be disposed in side on the left of crankcase 24.That is, this pedal part 37 has: the foot-operated arm 39 that the pedal axle 38 of ground axle suspension on crankcase 24 is installed is exposed in front end; Rotatably can be arranged on the foot treadle 40 of the front end of this foot-operated arm 39.Trample foot treadle 40 by driver and pedal axle 38 rotated thus 20 can be piloted engine.

And, on this two-wheeled motorcycle 1, except the kick-type starter controlled based on above-mentioned pedal part 37, be also equipped with the starting motor 41 of engine start.It is anterior that this starting motor 41 is arranged on crankcase 24 upper surface, can pilot engine 20 by making this starting motor 41 work.That is, in this two-wheeled motorcycle 1,20 can both be piloted engine by any one method in foot-operated and starting motor formula.

Fig. 2 is the in-built figure representing motor 20 on the right side of vehicle body, shows the position of the main running shaft of power-transmission system and starting system.In addition, also show cylinder axis L1.In addition, Fig. 3 is the figure in the III-III cross section representing Fig. 2, Fig. 4 is the figure representing crankcase 24 and cylinder part 22 on the right side of vehicle body together with peripheral structure, Fig. 5 (A), (B) represents that the figure of structure is analysed and observe in the superstructure of motor 20 and left and right.

As shown in Fig. 2 ~ Fig. 5, the cylinder part 22 of motor 20 has: the cylinder block 22A linked with crankcase 24 front surface; The cylinder head 22B linked with cylinder block 22A front surface; Cover the head-shield 22C of the front surface of cylinder head 22B.Cylinder block 22A is the part forming cylinder main body (cylinder principal part), has: the cylinder sleeve 22S (with reference to Fig. 3) that can keep piston 21A slidably; Form cooling fan (radiation fan) 22F of the cylinder cooling mechanism of the periphery covering this cylinder sleeve 22S.

This cylinder block 22A and cylinder head 22B are provided with through hole 42H (with reference to Fig. 4), and this through hole 42H and cylinder axis L1 is interspersed with stud bolt and the clamping bolt 42 of more than three (in this example being four) abreast.Clamping bolt 42 is inserted respectively in each through hole 42H, one end (cylinder block 22A side) of each clamping bolt 42 is fastened on crankcase 24, be fastened with tightening nut 43 at the other end (cylinder head 22B side) of clamping bolt 42, cylinder block 22A and cylinder head 22B is fastened on crankcase 24 integratedly thus.Here, cylinder block 22A and cylinder head 22B has the sectional shape of rectangle, and clamping bolt 42 is configured in (with reference to Fig. 4 and Fig. 5 (A), (B)) on each bight of the rectangular cross-section centered by cylinder axis L1 along cylinder axis L1.

As shown in Figure 2, cooling fan 22F is the cooling fan orthogonal relative to cylinder axis L1, more specifically, be located at the right flank of cylinder sleeve 22S and upper and lower surface and the planar extended on cylinder above-below direction and left and right directions, with formation multiple row spaced apart on cylinder axis direction.

As shown in the drawing, the outer circumferential face of multiple cooling fan 22F is when observing from lateral cylinder surface and observe from plan view, is respectively along linking plane HL that the cylinder axis L1 direction between clamping bolt 42 extends, HU, HB (with reference to Fig. 3, Fig. 2) formation with straight line.Therefore, the cylinder cooling mechanism be made up of multiple cooling fan 22F is formed as the roughly planar along the cylinder axis L1 direction extension linked with straight line between clamping bolt 42, is that lateral cylinder surface (cylinder block 22A side) is formed as plane shape.

Here, as shown in Figure 1, the body shell 18 due to this two-wheeled motorcycle 1 has the leg protective cover 18A extended to the rear lower side from body forward structure, so to flow downwards and at cylinder part 22 ambient dynamic along leg protective cover 18A from the traveling wind of vehicle front.Because above-mentioned cooling fan 22F is the fan extended in the vertical direction at lateral cylinder surface, so the flowing of the traveling wind down along leg protective cover 18A can not be hindered, traveling wind can be made easily to flow around cooling fan 22F, thus fully can guarantee radiating efficiency.

Not shown suction port cylinder head 22B being formed with firing chamber 22D and be connected with firing chamber 22D and relief opening, firing chamber 22D is configured with ignition spark plug 23 in the mode that front end is facing, inlet port is connected with above-mentioned suction tude 26, relief opening outlet is connected with above-mentioned outlet pipe 29.

As shown in Figure 3, the crankcase 24 of motor 20 is formed with the left and right two-part segmentation structure be made up of left crankcase 24A and right crankcase 24B.Via the pairing left and right bearing (rolling bearing) 45,45 be supported on crankcase 24A, 24B of left and right, it is anterior that bent axle 51 is laterally bearing in crankcase 24 by axle in the mode that axle center C1 is orthogonal with vehicle direct of travel.

Bent axle 51 has: the crankshaft journal 51A becoming rotating center; The crank arm 51B that diameter is larger than crankshaft journal 51A; Via this crank arm 51B by crankpin (eccentric shaft) 51C supported.Crank arm 51B and crankpin 51C is between pairing left and right bearing 45,45.In addition, crank arm 51B is provided with counterweight (hereinafter referred to as " the counterweight ") 51D for obtaining spin balancing.In addition, in Fig. 3, reference character 46 represents the bearing (rolling bearing) be configured between bent axle 51 and generator cover 25.

The piston 21A slidably configured along cylinder axis L1 in cylinder part 22 is attached on the crankpin 51C of bent axle 51 via connecting rod 21B.In Fig. 3, reference character 55A represents the sprocket wheel be located on bent axle 51, and reference character 55B represents the sprocket wheel be located on camshaft 55C, and wherein, camshaft 55C is located in the head-shield 22C of cylinder part 22, links between sprocket wheel 55A, 55B via cam chain 55D.Thus, the rotation of camshaft 55C and bent axle 51 correspondingly rotates, thus is driven for the active valve mechanism pressed the not shown air inlet-exhaust valve be located on cylinder head 22B.

Be provided with V variable v-belt drive 60 on the right side (side) of this bent axle 51, be provided with generator 180 in the left side (opposite side) of this bent axle 51.

Specifically, the left end of bent axle 51 extends to the left in left crankcase 24A, near the generator cover 25 that the mode extending to the left side opening (outer openings) covering this left crankcase 24A is installed, and be rotatably bearing in generator cover 25 by bearing (rolling bearing) 46.That is, generator 180 is housed in the space that surrounded by generator cover 25 and left crankcase 24A.Generator 180 has the rotor 181 be fixed on bent axle 51 and the stator 182 be configured in rotor 181, and stator 182 is fixed in generator cover 25.

V variable v-belt drive 60 does not carry out based on machine oil (below, be called suitable oil (lubricant oil)) the power transmission mechanism of dry type of lubrication, be housed in the speed changer accommodation section (cap assembly) 61 on the right side (side) being located at bent axle 51.This speed changer accommodation section 61 is the rooms not having fluid formed respectively with the crankcase 24 of oil lubrication, and with the formation of structure that left and right two-part that the speed changer cover 61B of the outer openings (right openings) of the mission case 61A of the main part forming speed changer accommodation section 61 and this mission case of covering 61A is such are split.

Specifically, the right-hand member of bent axle 51 runs through right crankcase 24B and extends to the right further, and run through by the mission case 61A of bolt link on the right side of this right crankcase 24B, extend near the speed changer cover 61B that is connected with on mission case 61A, this right part uses as rotating band wheel shaft (live axle) 51R of V variable v-belt drive 60, and this rotating band wheel shaft 51R is provided with driving pulley 63.

The driven belt wheel shaft (driven shaft) 64 of V variable v-belt drive 60 is bearing in crankcase 24 rear portion with the horizontal earth's axis of the mode that axle center C2 is orthogonal with vehicle direct of travel.This driven belt wheel shaft 64 is positioned at the rear of rotating band wheel shaft 51R abreast, and by being bearing in pairing left and right bearing (rolling bearing) 65, the 65 axle supporting on right crankcase 24B and speed changer accommodation section 61 (mission case 61A).

This driven belt wheel shaft 64 is provided with driven pulley 67, and between driving pulley 63 and driven pulley 67, be wound with V band 68, the rotation of driving pulley 63 is transmitted by driven pulley 67.In addition, between speed changer accommodation section 61 and each sprocket shaft 51R, 64, press from both sides sealed member 69A, 69B of being inserted with for preventing the engine oil of crankcase 24 side from invading in speed changer accommodation section 61, thus sealed between speed changer accommodation section 61 and crankcase 24.

Driving pulley 63 has the fixing halfbody 63A and movable halves 63B rotated together with rotating band wheel shaft 51R, and fixing halfbody 63A is fixed on rotating band wheel shaft 51R, and movable halves 63B is fixed on the left side of fixing halfbody 63A in the mode that can move freely in the axial direction.This movable halves 63B rotates together with bent axle 51, by because of centrifugal force to the counterweight roller 70 of centrifugal direction movement act on axially slide thus relative to fixing halfbody 63A close to or away from, thus change be clamped between two sprocket half 63A, 63B V band 68 roll diameter.

The driven pulley 67 of V variable v-belt drive 60 has the fixing halfbody 67A and movable halves 67B rotated together with driven belt wheel shaft 64, and fixing halfbody 67A is fixed on the left side of movable halves 67B.Movable halves 67B is configured in the right part of driven belt wheel shaft 64 with moving freely in the axial direction via ring-type slide block 71, (fixed halfbody 67A side) to the left suppress by disc spring and snap parts 72.Therefore, if the V between halved body 63A, 63B being clamped in driving pulley 63 is with the roll diameter of 68 to become large, then on the contrary, the interval of halved body 67A, 67B of driven pulley 67 is resisted the elastic force pressure of disc spring 72 and expands, thus reduce the roll diameter of V band 68, automatically can carry out stepless change.

Driven belt wheel shaft 64 via starting clutch 80 by transmission of power to the power transmission mechanism 81 be configured in crankcase 24, wherein starting clutch 80 is configured in the space (clutch chamber R1 described later) be formed between right crankcase 24B and mission case 61A.

Starting clutch 80 is the centrifugal clutchs being carried out the lubrication of each several part and the wet type of cooling by oil, there is the clutch Outside part 85 that spline is entrenched in clutch inner piece 83 on driven belt wheel shaft 64 and large footpath, wherein, clutch Outside part 85 is attached on clutch output gear 84, clutch output gear 84 is rotatably located at the left part of driven belt wheel shaft 64 relatively, and the multiple fulcrums 86 of side, periphery being darted at clutch inner piece 83 are provided with clutch weight 87.Therefore, when the rotational speed of driven belt wheel shaft 64 exceedes fixing speed, engaged with clutch Outside part 85 by the clutch weight 87 of centrifugal force to centrifugal direction movement, make clutch Outside part 85 and driven belt wheel shaft 64 rotate integratedly thus clutch output gear 84 is rotated.

In addition, in figure, reference character 88 represents the clutch reinforcing plate for suppressing clutch Outside part 85 to expand to centrifugal direction, and reference character 90 represents the spacer ring be configured between clutch output gear 84 and driven belt wheel shaft 64.This spacer ring 90 will have the roller row that two are listed in the bearing roller circumferentially configured at spaced intervals in the axial direction, by this two row roller row, clutch output gear 84 rotated relatively relative to driven belt wheel shaft 64.

Power transmission mechanism 81 be carry out V variable v-belt drive 60 and motor 20 output shaft 31 between the mechanism of transmission of power, and, be the mechanism played a role as reducing gear.This power transmission mechanism 81 is located between driven belt wheel shaft 64 and output shaft 31, have intermediate gear shaft (reducing gear wheel shaft) 91, this intermediate gear shaft 91 makes the rotation of the above-mentioned clutch output gear 84 be located on driven belt wheel shaft 64 slow down with regulation reduction speed ratio and transmit to output shaft 31.In addition, in Fig. 2, the axle center of intermediate gear shaft 91 represents by reference number C 3, and the axle center of output shaft 31 represents by reference number C 4.

Namely, in this motor 20, from V variable v-belt drive 60 to the power transmission mechanism 81 becoming a reducing gear, constitute the speed changer (engine side speed changer) of motor 20 side, that is, the power of V variable v-belt drive 60, starting clutch 80 and power transmission mechanism 81 structure coupled engines 20 carries out the engine side speed changer of speed change.In addition, the chain drive of formation secondary speed-reducing mechanism constitutes the speed changer (the outer gear of motor) outside motor 20.

On the pairing left and right bearing (rolling bearing) 92,92 that intermediate gear shaft 91 crankcase 24A, 24B that rotatably axle is bearing in left and right support, there is the through shaft portion 91A of the wall portion running through right crankcase 24B.This through shaft portion 91A is fixed with the counter shaft driven gear (reduction gear) 93 in the large footpath of engaging with the clutch output gear 84 be located on driven belt wheel shaft 64, in the space between crankcase 24A, 24B of left and right, be fixed with the countershaft drive gear 94 of the path engaged with the end gear 95 be fixed on output shaft 31.Thus, the rotation being positioned at the clutch output gear 84 outside crankcase 24 is transmitted via the end gear 95 of intermediate gear shaft 91 to the output shaft 31 being positioned at crankcase 24 with the reduction speed ratio of regulation.In addition, make countershaft drive gear 94 and end gear 95 be helical gear, the sound because gears meshing produces can be reduced.

Output shaft 31 is supported on pairing left and right bearing (rolling bearing) 96,96, and pairing left and right bearing 96,96 is supported on crankcase 24A, 24B of left and right.This output shaft 31 rotate free and can be provided with end gear 95 movably in the axial direction, the rotation of this end gear 95 is transmitted to this output shaft 31 via the torsional damper (gear dampers) 97 of cammingly.

This torsional damper 97 is supported on output shaft 31, by have by elastic member (in this example for multi-disc belleville spring) the elastic force pressure friction apply of 99 and the end gear (the first transferring elements) 95 of intermeshing not shown cam configuration and damper holding member (the second transferring elements) 98 are formed.End gear 95 rotatably remains on output shaft 31, and suppressed to the right by the folder belleville spring 99 be inserted on the left of end gear 95, in addition, damper holding member 98 is pressed into fixed on output shaft 31 on the right side of end gear 95.Therefore, driving torque is being acted on from motor 20 side, and when not acting on from driven wheel side (trailing wheel 15 side) to reciprocal torque (i.e. countertorque) with driving direction, by the driving torque from motor 20 side, output shaft 31 and end gear 95 rotary actuation integratedly, the trailing wheel 15 as driving wheel is driven.On the other hand, when acting on countertorque from driven wheel side (trailing wheel 15 side), by this countertorque, friction apply between end gear 95 and damper holding member 98 is removed, the not shown convexo-convex wheel of damper holding member 98 slides in a circumferential direction relative to the not shown concave of end gear 95, and the transmission to the countertorque of motor 20 side is relaxed.Thus, the cammingly torsional damper that the countertorque from driven wheel side absorbs is configured between clutch Outside part 85 and Transmitted chains 34 in crankcase 24.

As mentioned above, in this motor 20, in the adjacent position, right side of the space that crankcase 24A, the 24B by left and right surrounds (hereinafter referred to as crankshaft room R0), be formed with the space (hereinafter referred to as clutch chamber R1) surrounded by right crankcase 24B and mission case 61A.That is, mission case 61A is attached on right crankcase 24B, doubles as the clutch box body component into forming clutch casing thus.

And this crankshaft room R0 and clutch chamber R1 is the room that engine oil carries out lubricating and cooling, form oily delay portion (being equivalent to food tray 114) in crankcase 24 bottom and mission case 61A bottom.

In addition, in the adjacent position, right side of this clutch chamber R1, be formed with the space (hereinafter referred to as speed changer room R2) surrounded by mission case 61A and speed changer cover 61B, this speed changer room R2 carries out the lubrication of engine oil and the room of cooling.That is, in this motor 20, the room that engine oil exists and non-existent room are distinguished clearly on overall width direction.In addition, in Fig. 2, reference character R2A is the bottom surface of speed changer room R2.

As shown in Figure 2, pedal axle 38, in the front lower place of driven belt wheel shaft 64, is configured in and observes from the side on nonoverlapping position with the driven pulley 67 being formed as large footpath.The foot-operated jack shaft 150 be made up of the first foot-operated jack shaft 151 and the second foot-operated jack shaft 155 that is rotated through of pedal axle 38 is passed to bent axle 51.

First foot-operated jack shaft 151 is below the neutral position of driven belt wheel shaft 64 and bent axle 51, observed on overlapping position from the side by the driven pulley 67 be disposed transversely on be formed as large footpath, second foot-operated jack shaft 155 is in the rear lower side of bent axle 51, observed from the side on nonoverlapping position by the driven pulley 67 be disposed transversely on being formed as large footpath, and be configured to engage with the foot pedal starting driven gear 172 (with reference to Fig. 3) be located on bent axle 51.Here, in fig. 2, the axle center of pedal axle 38 reference character K1 is represented, the axle center of the first foot-operated jack shaft 151 is represented with reference character K2, the axle center of the second foot-operated jack shaft 155 is represented with reference character K3.

Below the wind-guiding construct of V variable v-belt drive 60 is described.

Fig. 6 is the side view that (outside motor) observes mission case 61A on the right side of vehicle body, and Fig. 7 is the side view that (inside motor) observes mission case 61A on the left of vehicle body.

In the R2 of speed changer room, that is in speed changer accommodation section 61, be imported with outer gas, the outer gas being configured to be imported into by this is cooled V variable v-belt drive 60.

As shown in Figure 6, be provided with outer gas suction port 115 at the front upper part being equivalent to the mission case 61A above driving pulley 63, be provided with outer gas relief opening 116 the superior posterior being equivalent to the mission case 61A above driven pulley 67.These outer gas suction ports 115 and outer gas relief opening 116 are arranged at spaced intervals in front and back, and have the pipe section 115A, the 116A that extend abreast rearwardly and upwardly, and are formed on mission case 61A.And, be connected with not shown pipeline in the upper end portion of these outer gas suction ports 115 and outer gas relief opening 116, can free flow via the outer gas of this pipeline.In addition, in Fig. 6, reference character 62 is Drainage Divisions of the water for discharging (in the R2 of speed changer room) in mission case 61A.

As shown in Figure 3, the fixing halfbody 63A of the driving pulley 63 be configured in speed changer accommodation section 61 is provided with the air-supply fan 63C for making this driving pulley 63 play blowing fan effect, by the rotation of driving pulley 63, air-supply fan 63C rotates, and outer gas is delivered in the R2 of speed changer room by from outer gas suction port 115.

And, the fixing halfbody 67A of the driven pulley 67 in speed changer accommodation section 61 is also provided with the air-supply fan 67C for making driven pulley 67 play blowing fan effect, by the rotation of air-supply with fan 67C, the outer gas be delivered into from outer gas suction port 115 can be introduced to driven pulley 67 side in the R2 of speed changer room, can be exhausted from outer gas relief opening 116.Thus, in the R2 of speed changer room, generate the outer air-flow from driving pulley 63 side direction driven pulley 67 side, V variable v-belt drive 60 is forced air cooling.

In addition, in Fig. 6, the sense of rotation of driving pulley 63 and driven pulley 67 is represented with solid arrow, observe all to right rotation from right flank, outer gas can be sucked swimmingly thus from outer gas suction port 115, and the outer gas (in Fig. 6, being represented by dotted arrow) sucked can be exhausted from outer gas relief opening 116 swimmingly.It is more than the explanation of wind-guiding construct.In addition, it is to anticlockwise (Fig. 2, shown in solid arrow) that the forward direction of intermediate gear shaft 91 is observed from right flank, and it is to right rotation (Fig. 2, shown in solid arrow) that the forward direction of output shaft 31 is observed from right flank.

Next oil lubrication structure is described.

As shown in Figure 4, in the crankcase 24 of this motor 20, be provided with the oil pump 120 supplied to each several part of motor 20 by engine oil.The oblique below, front that this oil pump 120 is located at bent axle 51, driven by cam chain, and driven by the rotating force of bent axle 51 and discharge engine oil, by this engine oil to supplies such as the active valve mechanism (not shown) of each bearing such as bearing 45,45 of supporting crankshaft 51, cylinder part 22, starting clutch 80 and power transmission mechanisms 81.

In addition, this motor 20 has the one-piece type small-sized oil cooler 105 of motor, and the oil of each several part of this oil cooler 105 pairs of lubricating engines 20 cools.This oil cooler 105 has: when mission case 61A casts and the oil cooler main body (extension part) 106 of the integrally formed tabular of this casing 61A; By the oil cooler cover of bolt link in this oil cooler main body 106 (oil circuit cover) 107.Here, Fig. 8 (A) ~ (D) shows oil cooler cover 107.In addition, Fig. 8 (D) represents the D-D cross section of Fig. 8 (A).

As shown in Fig. 6 and Fig. 7, oil cooler main body 106 extends from mission case 61A in cylinder axis L1 direction, be formed as the tabular of the side being positioned at cylinder part 22 (cylinder block 22A), and extend along it at spaced intervals on the plane HL of cooling fan 22F forming cylinder cooling mechanism.In addition, this oil cooler main body 106 is roughly along the shape that the front surface of crankcase 24 extends in roughly vertical direction, oil circuit (hereinafter referred to as cooling oil road) 108A is formed in the mode extended along the outer shape of this oil cooler main body 106.

That is, this cooling oil road 108A is formed as long in roughly vertical direction, and crooked roughly ring-type short in the longitudinal direction, and be connected in the pair of openings portion 110,111 of formation oil-in and oil export.In addition, at the outer surface of this oil cooler main body 106, namely in the side of cylinder side, be formed with cancellate cooling fan 106A (with reference to Fig. 7), by this cooling fan 106A, add the surface area of oil cooler main body 106, thus more effectively can be cooled through the oil of cooling oil road 108A.In addition, this cooling fan 106A is formed as cancellate ribbed, this improves the rigidity of oil cooler main body 106.

Oil cooler cover 107 is the lids covered the cooling oil road 108A of oil cooler main body 106.As shown in Fig. 8 (A) ~ (D), on this oil cooler cover 107, be integrally formed with the cooling oil road 108B (with reference to Fig. 8 (C)) that forms a cooling oil road 108 with cooling oil road 108A combinedly and formed along the periphery of this cooling oil road 108B and insert the seal groove 108C (reference Fig. 8 (C)) of oil seal, meanwhile, outer surface (face contrary with cylinder part 22) is formed with the many cooling fans 109 that the shape that is in line along the vertical direction extends.

Like this, in oil cooler main body 106 and oil cooler cover 107, be provided with cooling oil road 108A, 108B respectively and form the cooling fan 106A, 109 of cooler cooling mechanism, therefore, cooling oil road 108A, 108B can be made close to cooling fan 106A, 109, the cooling effectiveness of the engine oil by cooling oil road 108 can be improved.

In addition, because cooling fan 109 is the fans extended along the vertical direction, so can not hinder the flowing along the downward traveling wind of leg protective cover 18A, traveling wind easily can guarantee radiating efficiency efficiently at cooling fan 109 ambient dynamic.In addition, oil cooler cover 107 can be reinforced by this cooling fan 109.In addition, in figure, reference character 107A is for oil cooler cover 107 being fastened by bolts the bolton portion with through hole in oil cooler main body 106.

As shown in Figure 2, this oil cooler 105 observes from the side with cylinder axis L1 as downward-extension on benchmark, its lower end PA is positioned at the position slightly lower than bent axle 51, and be positioned at the top of the base portion lower end of cylinder block 22A, its upper end PB is positioned at the position higher than bent axle 51, and is positioned at the height identical with the base portion upper end of cylinder block 22A.Therefore, oil cooler 105 is observed overlapping with cylinder block 22A from the side, and can suppress to observe from the side oil cooler 105 and give prominence to from motor 20, that is, can suppress the outstanding of motor 20 above-below direction forwards, backwards.

In addition, because this motor 20 is single cylinder motor, so compared with the Extreme breadth of the left and right directions of motor 20, the width of cylinder part 22 is narrow, cylinder part 22 and form motor 20 side cap assembly mission case 61A between be formed with end difference X (with reference to Fig. 2).As shown in Figure 2, because above-mentioned oil cooler 105 is located on the end difference X between cylinder part 22 and mission case 61A, so it is outstanding to suppress from top view oil cooler 105 from motor 20, that is, left and right directions outstanding to motor 20 can be suppressed.Therefore, suppress oil cooler 105 from the outstanding of motor 20 completely thus the maximization of motor 20 can be avoided, and, oil cooler 105 can be made not maximize highlightedly, and oil cooler 105 can be protected.

In addition, the lower end PA of oil cooler 105 is positioned at the top of the food tray 114 (with reference to Fig. 4) that the oil measure of crankcase 24 is stayed.That is, as shown in Figure 4, food tray 114 is arranged on the height be communicated with in the horizontal direction with filter chamber 121, this filter chamber forms oil pump 120 sucking-off oil filtration device, therefore, be positioned at crankcase 24 bottom, and adverse current can not be located at the position lower than cylinder part 22 to the mode of cylinder part 22 to be trapped in oil in food tray 114.

Therefore, the oil cooler 105 of this structure is arranged on really high than the upper liquid level UL (with reference to Fig. 2) of the oil be trapped in food tray 114 position, and configures with leaving from food tray 114.If oil cooler 105 and food tray 114 configure with leaving, then due to after the lubrication of carrying out each several part and cooling, the oil temperature that deadweight drops to high temperature in food tray 114 is difficult to transmit to oil cooler 105, therefore, it is possible to improve the cooling effectiveness of oil cooler 105.

In addition, as shown in Figure 4, oil pump 120 is located at the top of filter chamber 121, and via the suction oil circuit 122 of downward-extension in right crankcase 24B, oil pump 120 is communicated with filter chamber 121.In addition, between filter chamber 121 and suction oil circuit 122, be configured with oil strainer 123, by this oil strainer 123, be cleaned (filtration) by the oil that oil pump 120 sucks.

Fig. 9 is the figure representing oil lubrication system.In addition, the flowing of oil is represented in fig .9 by solid arrow.

As shown in Figure 9, oil pump 120 is positioned at food tray 114 downstream via oil strainer 123 and suction oil circuit 122, and by this oil pump 120, the oil be trapped in food tray 114 is picked up.This oil pump 120 has single oily ejiction opening 120A (with reference to Fig. 5 (B)), this oily ejiction opening 120A is connected with working connection 131, sprays oil to this working connection 131.

As shown in Fig. 5 (B), this working connection 131 has: be formed in the first oil circuit 132 in the right crankcase in the wall of right crankcase 24B in the mode be communicated with oily ejiction opening 120A; The first oil circuit 133 in the mission case in the wall of mission case 61A is formed in the mode be connected with the downstream of the first oil circuit 132 in this right crankcase.Namely, in right crankcase the downstream of the first oil circuit 132 be in right crankcase 24B with the interface upper shed of mission case 61A, and with being communicated with the first oil circuit 133 in the mission case of the interface upper shed of right crankcase 24B in mission case 61A.

In this mission case, the first oil circuit 133 is communicated with the opening portion 111 (with reference to Fig. 7) of the oil circuit entrance becoming oil cooler 105.Therefore, as shown in Figure 9, the oil in working connection 131 is fed into oil cooler 105 and by air cooling.

Become on the opening portion 110 of oil circuit outlet of oil cooler 105 at this, as shown in Figure 7, be connected with the second oil circuit 134 in the mission case in the wall being formed in mission case 61A, in this mission case the downstream of the second oil circuit 134 be in mission case 61A with the interface upper shed of right crankcase 24B.On the other hand, on the interface of the mission case 61A in right crankcase 24B, to be formed in the right crankcase in the wall of right crankcase 24B the second oil circuit 135 (with reference to Fig. 4) with the mode opening be communicated with the second oil circuit 134 in mission case.

As shown in Figure 4, in right crankcase, the second oil circuit 135 is from oil cooler 105 to being configured in the bent axle 51 at rear of this oil cooler 105 and the oil circuit extended in right crankcase 24B.As shown in Figure 9, crankpin 51C is lubricated through oil circuit 135A by the oil of oil cooler 105.In addition, be branched off into oil circuit 135B by the oil of oil cooler 105, and play a role as the driven bearing clutch lubrication oil circuit according to the bearing (driven bearing) 65 of driven belt wheel shaft 64 and the sequentially feeding oil of starting clutch 80.

Figure 10 represents the lubricating structure of crankpin 51C.

As shown in the drawing, be fed into the oil of the oil circuit 135 in right crankcase 24B, pass through the inner side with groove 51M and by being supported in the bearing 45 on right crankcase 24B by the oil be formed on bent axle 51, and be fed into the crankpin 51C be configured between left and right crankcase 24A, 24B.And this oil is fed into the large end of connecting rod 21B by the oil circuit 51N being formed in the path on crankpin 51C.

That is, in this configuration, at the outer circumferential face of bent axle 51, and form gap between the bearing 45 on right side thus form the oil that oil is passed through to crankpin 51C side and pass through to use groove 51M, thus, without the need to forming oil circuit in bent axle 51, the structure of the supplies such as the slip surface making oil to connecting rod 21B just can be formed.In addition, oil, also can arrange one during sufficient lubrication by can arrange several in the circumferentially spaced apart of bent axle 51 with groove 51M.In addition, the bearing 45 be supported on right crankcase 24B adopts stuffing box bearing, oil can not enter in this bearing 45.

As shown in Figure 9, in this motor 20, between oil pump 120 and oil cooler 105, be branched off into the first auxiliary oil circuit 136A and the second auxiliary oil circuit 136B from working connection 131.First auxiliary oil circuit 136A from working connection 131 via throttle orifice (throttling) 137A branch, and via cylinder block 22A to cylinder head 22B for oil supply.Second auxiliary oil circuit 136B from working connection 131 via throttle orifice 137B branch, and to piston nozzle 138 for oil supply.

In this situation, oil circuit (cylinder head lubricating oil path) 136A is as shown in the flowing of oil indicated by the arrow in Fig. 4 and Fig. 5, be configured to comprise a through hole 42H in multiple (in this example being four) through hole 42H, wherein multiple through hole 42H runs through cylinder block 22A and cylinder head 22B and has inserted clamping bolt 42.Therefore, gap between the clamping bolt 42 that oil is interted in this through hole 42H with gap by through hole 42H and separating, and move to cylinder head 22B effluent via cylinder block 22A, by the oil drainage hole 139 (with reference to Fig. 4) in cylinder block 22A, the active valve mechanism etc. be configured in cylinder head 22B is lubricated.Like this, due to oil circuit can be also used as by running through the through hole 42H having clamping bolt 42, so the rigidity of cylinder part 22 can be avoided to reduce and realize miniaturization.

In addition, the second auxiliary oil circuit 136B is formed as the sectional area in thin footpath compared with other the oil circuit in through cylinder sleeve 22S, to spraying the piston nozzle 138 of oil towards piston 21A for oil supply, carries out lubrication and the piston cooling in piston lubrication portion.In this situation, owing to being via throttle orifice 137B to piston nozzle 138 confession oil supply, therefore, it is possible to guarantee the oil pressure of piston nozzle 138.

Like this, in the motor 20 of present embodiment, to extend on cylinder axis L1 direction owing to having and to be positioned at the oil cooler 105 of the tabular of the side of cylinder part 22, so oil cooler 105 can be configured along cylinder side wall, the outstanding of oil cooler 105 can be suppressed.

And, the cooling fan 22F forming cylinder cooling mechanism observes from lateral cylinder surface and is formed as along linking the plane of plane HL that the cylinder axis L1 direction between clamping bolt 42 extends with straight line, because oil cooler 105 extends at spaced intervals on this plane HL, so oil cooler 105 can be configured close to cylinder part 22 (cylinder block 22A), even large-scale oil cooler 105 also can suppress its outstanding from motor 20.

In addition, in this structure, motor 20 is configured to the horizontal engine in the front of the bent axle 51 be supported on crankcase body 24 with cylinder part 22 (cylinder block 22A), and, be configured to, at crankshaft end, there is mission case 61A, there is food tray 114 below bent axle 51, in the structure shown here, owing to oil cooler 105 to be configured in the top of food tray 114, so have in the horizontal engine of mission case 61A at crankshaft end, the oil cooler of configuration highlightedly 105 of oil cooler 105 can be suppressed, and, oil cooler 105 and food tray 114 are configured with leaving, thus oil cooler 105 can be avoided to be subject to the impact of the oil temperature in food tray 114 and to make temperature increase.In this situation, owing to improve the cooling effectiveness of oil cooler 105, so the amount that can improve with cooling effectiveness correspondingly makes oil cooler 105 miniaturization.

In addition, contain in mission case 61A and do not need lubricant oil to carry out the V variable v-belt drive 60 lubricated, because oil cooler 105 is formed in the front upper part of mission case 61A, so in inside be dry space box part on be formed with oil cooler 105, and, oil cooler 105 configures from food tray 114 with leaving, and can improve the cooling effectiveness of oil cooler 105 further.

In addition, between the crankshaft lubrication portion (bearing 45,45) being configured in oil pump 120 due to oil cooler 105 and being positioned at its downstream, so the oil cooled by oil cooler 105 can be supplied to crankshaft lubrication portion, even the not too good motor of the thermal diffusivity of crankshaft room also can carry out good cooling to crankshaft room.

In addition, owing to being provided with the first auxiliary oil circuit 136A (cylinder head lubricating oil path), this first auxiliary oil circuit 136A between oil pump 120 and oil cooler 105 via throttle orifice 137A branch, and oil is supplied to the cylinder head 22B be arranged on cylinder block 22A, so without the need to lengthening the supply oil circuit to cylinder head 22B, just can carry out the lubrication in cylinder head lubrication portion (active valve mechanism) etc. and the cooling based on oil well, and cylinder head lubrication portion oil-break can be prevented.

In addition, owing to having piston nozzle 138, this piston nozzle 138 between oil pump 120 and oil cooler 105 via throttle orifice 137B branch, and spray oil, so the oil pressure of piston nozzle 138 can be guaranteed to the piston 21A that is free to slide in cylinder.

In addition, due to the inner space at mission case 61A, cooling air is by suction and discharge, oil cooler 105 is integrally formed on mission case 61A, so also act on oil cooler 105 via mission case 61A based on the cooling effect of internal cooling wind, thus improve the cooling effectiveness of oil cooler 105.

In addition; because cylinder part 22 (cylinder block 22A) configures relative to the horizontal forward direction of bent axle 51; there is in bent axle side mission case (cap assembly) 61A; oil cooler 105 is configured on the end difference X between cylinder part 22 (cylinder block 22A) and mission case 61A; so the maximization of motor 20 can be avoided, and realize maximization and the protection of oil cooler 105.

In addition, because oil cooler 105 has in the side of the side of cylinder side and the opposition side of cylinder the cooling fan 109, the 106A that play a role as cooler cooling mechanism, so can increase and guarantee heat diffusion area, improve cooling effectiveness.

Above, describe the present invention based on a mode of execution, but, the present invention is not limited thereto.Such as, in the above-described embodiment, the situation being made up of the cooling mechanism of oil cooler 105 cooling fan 109 of air cooling, 106A is illustrated, but, be not limited thereto.Such as, can also be configured to form water passage on oil cooler 105, make cooling water flow through this water passage thus make oil cooler 105 become water-cooled.In this situation, for the water passage forming cooler cooling mechanism, be formed as plane along what extend with the cylinder axis L1 direction between straight line link clamping bolt 42, and, oil cooler 105 is extended at spaced intervals, thereby, it is possible to configured close to cylinder part 22 (cylinder block 22A) by oil cooler 105 along this plane, even large-scale oil cooler 105, its outstanding from motor 20 also can be avoided.

In addition, in the above-described embodiment, be illustrated being suitable for situation of the present invention in single cylinder motor, but be not limited thereto.And be not limited to be suitable for situation of the present invention in the power unit cooling unit of two-wheeled motorcycle, the power unit cooling unit of riding vehicle also can be suitable for the present invention.In addition, refer to that striding across vehicle body carries out rolling stock by bus as riding vehicle, be not only two-wheeled motorcycle (also comprising the bicycle of band prime mover), comprise the three-wheeled vehicle and four-wheel car that are divided into ATV (All-terrain moving vehicle), and comprise the scooter of the pin mounting portion with low base plate.

Claims (6)

1. a cooling unit for power unit, described power unit has crankcase and cylinder, and described cylinder has the cylinder cooling mechanism of the cylinder sleeve that slidably can keep piston and the periphery covering this cylinder sleeve, it is characterized in that,

Described power unit is the air-cooled engines that described cylinder cooling mechanism is made up of multiple cooling fan, described air-cooled engines has in the front being bearing in the bent axle on crankcase and is configured to horizontal forward cylinder, at crankshaft end, there is mission case, below bent axle, there is food tray

Described mission case collecting V belt-type transmission, in the inner space of this mission case, cooling air by suction and discharge,

Described cylinder by with the clamping bolt of more than configure roughly at equal intervals three and described crankcase fastened integratedly, and described multiple cooling fan is at least arranged on the side in the overall width direction of described cylinder sleeve,

The cooling unit of described power unit has oil cooler, this oil cooler has the oil circuit passed through for the oil being fed into described air-cooled engines, the cooler cooling mechanism cooled the oil by this oil circuit, and there is in described bent axle side the described mission case of the part forming cap assembly

Described oil cooler be configured in described food tray top and in the front upper place of described mission case, end difference between described cylinder and described cap assembly, extend along cylinder axis direction at spaced intervals to the outer circumferential face outside the overall width direction of described cooling fan in overall width direction, and described oil cooler is integrally formed on described mission case in mode overlapping with described cylinder under side-looking

Described oil cooler has the cooling fan as described cooler cooling mechanism on the side of the side of cylinder side and the opposition side of cylinder.

2. the cooling unit of power unit as claimed in claim 1, is characterized in that,

Described cylinder cooling mechanism is formed as the roughly planar extended along the cylinder axis direction linked with roughly straight line between described clamping bolt, and described oil cooler extends at spaced intervals along the plane of described cylinder cooling mechanism.

3. the cooling unit of power unit as claimed in claim 1, is characterized in that,

Have oil pump, this oil pump picks up the oil of described food tray, and by oil to each several part supply comprising crankshaft lubrication portion,

Described oil cooler is configured in described oil pump and between the described crankshaft lubrication portion in its downstream.

4. the cooling unit of power unit as claimed in claim 3, is characterized in that,

There is cylinder head lubricating oil path, this cylinder head lubricating oil path between described oil pump and described oil cooler via throttle orifice branch, and by oil to be arranged on described cylinder cylinder head supply.

5. the cooling unit of the power unit as described in claim 3 or 4, is characterized in that,

There is piston nozzle, this piston nozzle between described oil pump and described oil cooler via throttle orifice branch, and oil to be sprayed to the piston that is free to slide in described cylinder.

6. the cooling unit of power unit as claimed in claim 1, is characterized in that,

Described cylinder configures frontward relative to bent axle level, and have cap assembly in described bent axle side, described oil cooler is configured on the end difference between described cylinder and described cap assembly.