CN101907008B - Motorcycle engine ventilating device - Google Patents

Abstract

The present invention provides a breather device for a motorcycle engine, which can effectively achieve miniaturization and weight reduction, as well as simplification of structure and processing. The motorcycle engine has an engine case including a crankcase (12) equipped with a crankshaft (25) and a gearbox (19) equipped with a plurality of speed change gears. A breather box (22) is arranged on the rear upper surface of the engine case, and an oil return passage (74) communicated with the breather box (22) is formed on the rear wall (19c) of the engine case, from the crankcase ( 12) Leakage gas is introduced into the vent box (22) for gas-liquid separation, and the separated oil returns to the oil storage part (24) through the oil return passage (74).

Description

Ventilation device for motorcycle engine

technical field

The invention relates to a ventilation device (Japanese: ブリザザ device) for engines such as motorcycles, and in particular to an oil return passage structure.

Background technique

In such an engine, gas (blow-by gas) leaking from the combustion chamber into the crank chamber is generated. When the pressure in the crank chamber increases due to the generation of blow-by gas, lubricating oil may leak from the oil seal member, etc., so the blow-by gas is generally discharged to the outside of the engine to prevent the internal pressure of the crank chamber from rising.

In this case, since the blow-by gas contains unburned gas and lubricating oil, in consideration of environmental issues, a structure is generally adopted so that it is not discharged into the atmosphere but returned into the engine. The engine that returns the leaked gas into the engine is configured such that the leaked gas is gas-liquid separated into gas and lubricating oil in the breather, wherein the gas is returned to the suction device side, and the lubricating oil is returned to the oil reservoir.

Especially for the engine that uses the crankcase that splits up and down, for example, the engine described in Patent Document 1, if a breather chamber is provided in the crankcase, the lubricating oil after gas-liquid separation in the breather chamber passes through the crankcase and the crankcase. The passage provided between the gearbox chambers is sent back to the oil reservoir.

Patent Document 1 Japanese Patent Application Laid-Open No. 8-189325

Contents of the invention

The problem to be solved by the invention

However, in an engine in which the gap or interval between the crank chamber and the transmission chamber is small, the space in the engine interior that can be used to arrange the oil return passage is extremely limited. In addition, it is substantially difficult to arrange, for example, a battery motor (starter motor) between this space (or interval) and the breather chamber outside the engine, and to form an oil return passage between the crank chamber and the transmission chamber.

As a countermeasure against this, there is a technique of forming an oil return passage using another member such as a pipe or a hose. Or as shown in Figure 12, the following method can be adopted: a plurality of speed change gears 200A are arranged in the gearbox chamber (gearbox) 200, and the oil return passage 202 is protrudingly arranged on the outer wall 201 of the gearbox chamber 200, through which The oil return passage 202 returns oil from the breather chamber 203 and the like. However, when other components are typically used in this example, the dead bolt 204, the channel 205 for mounting it, and the processing bolt 206 become necessary. Therefore, this becomes disadvantageous in saving the space of the engine, reducing the number of parts, and the like.

In view of the actual situation, the object of the present invention is to provide a breather device for a motorcycle engine, which can effectively achieve miniaturization and weight reduction, and realize simplification of structure and processing.

means to solve the problem

The ventilation device for a motorcycle engine of the present invention, the motorcycle engine has an engine case, the engine case includes a crankcase configured with a crankshaft and a gearbox configured with a plurality of speed change gears, the ventilation device is characterized in that it includes:

a breather box, which is arranged on the rear upper surface of the engine box;

an oil return passage formed on a rear wall of the engine case communicates with the breather case,

Wherein, the breather box guides leakage gas from the crankcase to the breather box for gas-liquid separation, and returns the separated oil to the oil pan through the oil return passage.

In addition, the breather device for a motorcycle engine according to the present invention is characterized in that the crankcase and the gearbox are formed to communicate with each other in the engine case, and the oil return passage is formed in a part of the engine case. A part of the rear wall of the gearbox protrudes toward the inner side of the gearbox.

In addition, the breather device of the motorcycle engine of the present invention is characterized in that the oil return passage is arranged correspondingly to a gear with a non-largest diameter among all the transmission gears arranged in the gearbox.

In addition, the breather device of the motorcycle engine of the present invention is characterized in that it further has a starter motor installed on the upper surface of the engine case, and the starter motor is arranged between the cylinder extending upward from the engine case and the breather case. between.

In addition, the breather device for a motorcycle engine according to the present invention is characterized in that the oil return passage is arranged so as to overlap with at least one speed change gear arranged in the transmission case when viewed from the side.

The effect of the invention

According to the present invention, the engine can be arranged at an optimal position without interference with the vehicle body frame by making the oil return passage protrude inwardly of the transmission instead of protruding rearward. Specifically, by correspondingly arranging the non-maximum-diameter transmission gears in the gearbox, especially the minimum-diameter transmission gears, mutual interference can be prevented, and at the same time, the size of the engine case can be effectively realized. Furthermore, by arranging the starter motor and the breather box side by side on the upper surface of the engine case, the size can be reduced, and the appropriate arrangement relationship with the peripheral auxiliary machinery can be maintained to make a better arrangement structure of the breather box.

Description of drawings

Fig. 1 is a side view of a motorcycle according to an embodiment of the present invention.

Fig. 2 is a side view showing the periphery of the power unit of the motorcycle according to the embodiment of the present invention.

Fig. 3 is a perspective view showing the periphery of the power unit of the motorcycle according to the embodiment of the present invention.

Fig. 4 is a perspective view showing a power unit of the motorcycle according to the embodiment of the present invention.

Fig. 5 is a side view and a plan view showing the upper part of the engine case of the motorcycle engine according to the embodiment of the present invention.

Fig. 6 is a plan view showing the lower part of the engine case of the motorcycle engine according to the embodiment of the present invention.

Fig. 7 is a plan view showing a configuration example in a gearbox of a motorcycle engine according to an embodiment of the present invention.

Fig. 8 is a perspective view showing the lower part of the engine case of the motorcycle engine according to the embodiment of the present invention.

Fig. 9 is a sectional view along the oil return passage of the motorcycle engine according to the embodiment of the present invention.

Fig. 10 is a diagram showing an arrangement relationship of transmission gears in an oil return passage of a motorcycle engine according to an embodiment of the present invention.

Fig. 11 is a right side view showing a motorcycle engine according to an embodiment of the present invention.

Fig. 12 is a diagram showing a configuration example of a conventional ventilation device.

Symbol Description

10: power unit; 11: engine; 12: crankcase; 12a: left side wall; 12b: rear wall; 13: upper part of crankcase; 13a, 14a: mating surface; 14: lower part of crankcase; 15: cylinder; 16 : cylinder head; 17: cylinder head cover; 18: starter motor; 19: gearbox; 19a: left side wall; 19A: upper box; 19B: lower box; 20: magnetic cover; 21: clutch cover; 22: ventilation box ; 23: ventilation cover; 24: oil pan; 25: crankshaft; 25a: crank arm; 26: axle center; 27: metal bearing (bearing part); 28: auxiliary shaft; 33: bearing; 34: primary driven wheel; 35: bearing; 36: clutch device; 37: clutch separation mechanism; 38: clutch housing; 39: clutch hub; 40: pressure plate; 41: driving plate; 42: driven plate; 43: Clutch spring; 44: Clutch release part; 45: Primary shock absorber; 46: Rivet parts; 47: Spline shaft; 48, 49: Gear group; 50: Drive sprocket; 51: Step part; 52: Clutch Line; 53: outer tube; 54: stop part; 55: clutch release bracket; 56: clutch release shaft; 57: cam piece; 58: clutch release arm; 58a: front end; 59: front end; 60: storage part ;61: push rod; 62: intermediate rod; 63: main passage; 64, 65, 66, 67: oil passage; 68: oil leakage prevention groove; 69: ventilation chamber; 70: blowing part; 71: leakage gas introduction Passage; 72: hose; 73: communication hole; 74: oil return passage; 100: motorcycle; 101: body frame; 102: head tube; 103: front fork; 104: steering rod; 105: handle; 106: Clutch lever; 107: rearview mirror; 108: front wheel; 109: front fender; 110: brake disc; 111: fuel tank track; 112: body frame; 113: drop tube; 114: down tube; 115: seat strut; 116: seat rail; 117: pivot bracket; 118: pivot; 119: swing arm; 120: rear wheel; 121: chain; 122: driven sprocket; 123: engine setup; 124: fuel Box; 125: seat; 126: rear fender; 127: upper bracket; 128: lower bracket; 129: headlight unit; 130: instrument unit; 131A～131C: covers; 132: front light; 133 : Tail lamp; 134: Air filter; 135: Throttle valve body; 136: Actuator; 137: Injector; 138: Discharge pipe; 139: Muffler; 140: Catalytic device; 141: Cooler unit; 142: Cooler; 143: hose; 144: water pump; 145: hose; 146: hose.

Detailed ways

Next, preferred embodiments of the breather device for a motorcycle engine according to the present invention will be described with reference to the drawings.

Here, first, the overall structure of the motorcycle 100 of the present embodiment will be briefly described. FIG. 1 shows a motorcycle 100 of this embodiment. In addition, in the main parts of each figure referred to below, the front is shown by the arrow Fr, and the rear is shown by the arrow Rr, respectively. In addition, the left-right direction (vehicle width direction) of the vehicle body is indicated by an arrow L and an arrow R, respectively, as necessary.

In FIG. 1 , two front forks 103 are rotatably supported by a head pipe 102 at the front of a vehicle body frame 101 made of, for example, steel or aluminum alloy. A steering rod 104 is fixed to an upper end of the front fork 103 , and handles 105 are provided at both left and right ends of the steering rod 104 . In addition, on the steering lever 104 on the left side, a clutch lever 106 is arranged on the front side of the handle 105 , and a rearview mirror 107 is erected near the base of the handle 105 . Further, a front wheel 108 is rotatably supported on a lower portion of the front fork 103 , and a front fender 109 is fixed to cover an upper portion of the front wheel 108 . The front wheel 108 has a brake disc 110 that rotates integrally therewith.

The vehicle body frame 101 of the present embodiment has a semi-double cradle structure. Referring again to FIGS. 2 and 3 , there is a pair of left and right fuel tank rails 111 extending rearward and downward from the head pipe 102 , and each fuel tank rail 111 is connected to a body frame 112 arranged substantially vertically. A single down tube 113 is steeply inclined toward the rear side from the head tube 102 and extends downward, and a pair of down tubes 114 branch off from the lower end of the down tube 113 . The down tubes 114 extend rearward in parallel to each other, and are joined to lower ends of the seat posts 115 . In addition, the body frames 112 are joined to the vicinity of the lower ends of the seat pillars 115 . The seat rail 116 extends from the vicinity of the upper portion of the vehicle body frame 112 in a posture inclined moderately rearward and upward, and the seat pillar 115 extending rearward and upward is coupled to the seat rail 116 . These frames or rails form the main skeleton of the vehicle body frame 101 .

A pivot bracket 117 is provided near the junction of the vehicle body frame 112 and the seat post 115 , and the tip of a swing arm 119 is vertically supported on a pivot shaft 118 set on the pivot bracket 117 . In addition, a rear buffer unit (not shown) is attached between the vehicle body frame 101 and the swing arm 119 , and a rear wheel 120 is rotatably supported at the rear end of the swing arm 119 . The rear wheel 120 can be rotationally driven by a drive sprocket 122 around which a chain 121 is wound.

The vehicle body frame 101 is provided with a plurality of engine mounts (engine suspension portions) 123 (one of which is shown in FIG. 2 ), and the power unit 10 including an engine and the like is mounted on these engine mounts 123 . The power unit 10 will be described in detail later. Above the power unit 10 , a fuel tank 124 is mounted and supported by a fuel tank rail 111 , and a seat 125 is supported by a seat rail 116 on the rear side of the fuel tank 124 . Below the rear portion of the seat 125, a rear fender 126 covering the rear wheel 120 from above is provided.

In addition, in FIG. 1 , the headlight unit 129 is supported by the upper bracket 127 and the lower bracket 128 on the upper part of the front fork 103 . A meter unit 130 including a speedometer, a tachometer, various indicator lights, and the like is mounted on the headlight unit 129 . Furthermore, casings or covers 131A to 131C are covered along the fuel tank 124 and the side surface of the seat 125 to the vicinity of the lower side, thereby constituting an appearance having a sense of unity on the vehicle. In addition, left and right pairs of headlights 132 and taillights 133 are attached to the front and rear of the vehicle, respectively.

Next, the periphery of the power unit 10 will be described. Referring to FIGS. 2 and 3 , in the air intake system for supplying air-fuel mixture to the engine 11 of the power unit 10 , an air filter 134 is supported by the vehicle body frame 101 at approximately the center of the vehicle body. This air filter 134 is connected to the inlet manifold of the engine 11 through a throttle valve body 135 . A throttle valve (not shown) that opens and closes the intake passage is arranged in the throttle body 135 , and the throttle valve can be driven and controlled by the actuator 136 . In addition, a fuel injector 137 is installed in the throttle body 135, and the injector 137 injects fuel supplied from the fuel tank 124 into the intake passage downstream of the throttle valve.

In addition, in the exhaust system of the engine 11 , an exhaust pipe 138 is connected to the exhaust manifold, and exhaust gas after combustion generated in the engine 11 is exhausted through the exhaust pipe 138 . A plurality of (two in this example) exhaust pipes 138 extend downward from the front portion of the power unit 10 , and extend rearward from the rear portion of the power unit 10 as an exhaust pipe gathered at the lower portion. This exhaust pipe is combined with a muffler (exhaust muffler) 139 . The lower part of the power unit 10 is provided with a catalytic device 140 in the middle of the exhaust pipe, and the exhaust gas cleaned and purified by the catalytic device 140 is discharged from the muffler 139 .

In addition, in this embodiment, the engine 11 is a water-cooled type, and therefore has a cooling system including a cooler unit 141 . In the cooler unit 141 , a cooler 142 is mounted in front of the engine 11 , and the cooling water cooled by the cooler 142 is guided to a water pump 144 through a hose 143 . The water pump 144 sends cooling water introduced from the cooler 142 to a water jacket formed on the cylinder block of the engine 11 through a hose 145 , thereby cooling the engine 11 . The cooling water that has cooled the engine 11 flows back to the cooler 142 through the hose 146 .

Here, FIG. 4 shows the power unit 10 . The engine 11 of power unit 10 has: the crankcase 12 that is integrally formed by crankcase top 13 (Fig. 5) and crankcase bottom 14 (Fig. 6), the cylinder 15 that combines with the front upper part of crankcase 12, further with cylinder The cylinder head 16 connected to the upper part of the cylinder head 15 and the cylinder head cover 17 covering the upper part of the cylinder head 16 are mounted on the vehicle body frame 101 in an integrated posture.

In addition, a crankshaft to be described later is rotatably supported in the crankcase 12, and a piston is housed in the cylinder 15 so as to reciprocate up and down, and both are connected by a connecting rod. In addition, the cylinder head 16 accommodates a movable valve device for opening and closing the intake valve and the exhaust valve.

In this example, a starter motor 18 is mounted on the crankcase upper portion 13 behind the cylinder 15 . In addition, the gearbox 19 is integrally formed in a state connected to the rear side of the crankcase 12 . In this case, the crankcase upper portion 13 and the crankcase lower portion 14 are respectively extended rearward, and these extended portions are integrally combined to form a transmission case 19 . The left shaft end of the crankshaft is configured with a generator device, and the generator device is covered by a magnetic cover 20 . A clutch device is disposed on a right shaft end portion of an after-mentioned countershaft arranged in parallel on the rear side of the crankshaft, and the clutch device is covered by a clutch cover 21 . In addition, a breather box 22 is provided on an upper portion of (the upper case 19A of) the transmission case 19 , and the breather box 22 is covered with a breather cover 23 . In addition, an oil pan 24 is arranged at the lower portion of these components across (the lower case 19B of) the transmission case 19 from the crankcase lower portion 14 . In addition, the crankcase 12 and the transmission case 19 are collectively referred to as an engine case.

The above components and the like of the power unit 10 will be further described in detail. 5 is a left side view and a top view showing the upper crankcase 13 , FIG. 6 is a top view showing the lower crankcase 14 (and the transmission case 19 ), and FIG. 7 is a top view showing the transmission case 19 . The crankcase 12 is constituted by upper and lower divisions of the crankcase upper part 13 and the crankcase lower part 14, and the metal bearing (or bearing part) 27 of the crankshaft 25 is formed in both the crankcase upper part 13 and the crankcase lower part 14. The height positions of the shaft center 26 of the crankshaft 25 are aligned on the mating surfaces 13a, 14a.

Since this example is a parallel cylinder engine, four metal bearings 27 are arranged along the vehicle width direction so as to pivotally support both sides of the crank arm 25a facing each cylinder. These metal bearings 27 are substantially arranged in the crankcase 12 so as to be centered in the left-right direction. That is, the crankshaft 25 and the metal bearing 27 are arranged substantially bilaterally symmetrical with respect to the engine center (center line CL).

As described above, the gearbox 19 is integrally formed on the rear side of the crank case 12 in a state extending rearward. As shown in FIG. 7 , inside the transmission case 19 , a counter shaft 28 and a drive shaft 29 are arranged in parallel with the crankshaft 25 in front and rear. The secondary shaft 28 is axially supported via bearings 30, 31 and the drive shaft 29 via bearings 32, 33, respectively.

The primary driven gear 34 is rotatably supported on one end side, for example, the right side, of the countershaft 28 via a bearing 35 , and a clutch device 36 is provided on the right side thereof. As shown in FIG. 7 , these primary driven gears 34 and clutch device 36 are arranged outside the engine case (transmission case 19 ). A clutch disengagement mechanism 37 is disposed on the other end side of the counter shaft 28 , that is, on the left end portion opposite to the clutch device 36 . Note that details of the clutch release mechanism 37 will be described later. A primary drive gear (not shown) provided on the crankshaft 25 always meshes with the primary driven gear 34 .

The clutch device 36 is made into a general multi-plate clutch, consisting of a clutch housing 38, a clutch hub 39, a pressing plate 40, a plurality of driving plates 41, a driven plate 42, a clutch spring 43, a clutch separating member 44, and the like. Among them, the clutch housing 38 rotates integrally with the primary driven gear 34 via a plurality of primary dampers 45 and a plurality of rivets 46 . On the other hand, the clutch hub 39 is coupled to the right end of the countershaft 28 through a spline 47 to integrally rotate and move freely in the axial direction.

The driving plate 41 and the driven plate 42 that overlap each other are integrally pushed toward the clutch hub 39 by the pressing plate 40 biased by the clutch spring 43 . Therefore, the clutch housing 38 and the clutch hub 39 are integrally rotated by the frictional force between each driving plate 41 and each driven plate 42 , and the rotation of the crankshaft 25 is transmitted to and below the countershaft 28 .

On the countershaft 28, gear groups 48 on the driving side are arranged along its axial direction; 49. The transmission gear consisting of the gear group 48 and the gear group 49 moves on the counter shaft 28 and the drive shaft 29 by a shaft mechanism not shown, thereby rotationally driving the drive shaft 29 at a desired gear ratio.

The left end side of the driving shaft 29 protrudes outward from the left side wall 19a of the transmission case 19, and the driving sprocket 50 provided on this protrusion and the driven sprocket 122 provided on the left side of the rear wheel 120 ( Referring to FIG. 1 ), a chain 121 is wound between them.

Here, in the present embodiment, the transmission case 19 and the transmission gears accommodated therein are disposed toward the clutch device 36 side. As shown in Figure 6 or Figure 7, the gearbox 19 is biased to the right from the center of the engine, thus forming a step difference between the left side wall 19a of the gearbox 19 and the left side wall 12a of the crankcase 12, and the crankcase 12 A stepped portion 51 is formed at the corner where the rear wall 12b of the rear portion 12b intersects with the left side wall 19a of the gearbox 19, and the clutch release mechanism 37 is disposed on the stepped portion 51. In addition, this step portion 51 is moderately thickened. The stepped portion 51 is arranged so as to deviate considerably to the right inner side of the drive sprocket 50 with a left-right gap or gap formed therebetween.

The clutch release mechanism 37 will be described in more detail. Here, as shown in FIG. 3 or FIG. 4, etc., at the top of the crankcase 13, specifically at the nearest left side of the top of the starter motor 18, a hanging part 54 is provided, and the hanging part 54 is used to hold the clutch line 52. (the end of) the outer tube 53 . The clutch circuit 52 is stretched and spanned between a clutch release arm described later of the clutch release mechanism 37 and the clutch lever 106 ( FIG. 1 ), and the clutch device 36 can be intermittently controlled by the operation of the clutch lever 106 .

In addition, in FIG. 3 or FIG. 4, etc., although the clutch line 52 and the outer tube 53 are straight in the drawing, they are actually attached so as to be properly bent and rolled up due to relations with peripheral components and the like.

And as shown in FIG. 5 , on the rear side of the starter motor 18 , on the right obliquely rear of the hook portion 54 , a cylindrical clutch release bracket 55 is erected integrally with the crankcase upper portion 13 and the upper case 19A of the transmission case 19 . . In this example, the clutch release bracket 55 extends obliquely rearward and upwardly from the stepped portion 51 with its cylindrical bottom formed on the stepped portion 51 . Like the stepped portion 55 , the clutch release bracket 55 also has a gap or space in the left-right direction with the drive sprocket 50 . In addition, this clutch release bracket 55 functions as a housing of the clutch release mechanism 37 .

A clutch release shaft 56 is rotatably supported in the clutch release bracket 55 via a bearing not shown (see FIG. 5 ). The lower end of the clutch release shaft 56 is fixed with a cam plate 57 as shown in FIG. 7 . The upper end portion of the clutch release shaft 56 protrudes moderately from the clutch release bracket 55 , and the clutch release arm 58 is coupled to the upper end. As shown in FIG. 4 and the like, the front end portion 58 a of the clutch release arm 58 is located behind the engagement portion 54 and constitutes an engaging portion that engages with the front end portion 59 of the clutch line 52 . In addition, a return spring (not shown) is attached to the upper end of the clutch release shaft 56 , and the clutch release shaft 56 is rotationally biased by the elastic force of the return spring so that the front end 58 a is separated from the hook portion 54 .

As shown in FIGS. 6 and 7 , etc., an accommodating portion 60 is formed in the stepped portion 51 of the crankcase lower portion 14 , and the cam piece 57 is rotatably accommodated in the accommodating portion 60 . The receiving portion 60 is the cylindrical bottom of the above-mentioned clutch release bracket 55 , and the cam plate 57 mounted on the lower end of the clutch release shaft 56 is capable of reciprocating rotation in the receiving portion 60 . Here, as shown in FIG. 7 , a push rod 61 is inserted into the counter shaft 28 so as to be reciprocatable in the axial direction. In addition, the push rod 61 pushes the clutch release member 44 through the intermediate rod 62 . The left end portion of the push rod 61 extends into the housing portion 60 , and the left end abuts against the cam piece 57 .

Here, lubricating oil is supplied in the housing part 60, that is, it has a function of retaining lubricating oil. As shown in FIG. 8 , a lubricating oil main passage 63 is formed at the bottom of the clutch case lower portion 14 along the vehicle width direction, and an oil pump (not shown) supplies lubricating oil to this main passage 63 . Lubricating oil is supplied from the main passage 63 to the necessary parts of the engine. In this lubricating system, for example, an oil passage 64 communicating with the main passage 63 is formed on a protruding portion of the bearing 27 , and lubricating oil is supplied to the bearing 27 through the oil passage 64 .

In addition, an oil passage 65 communicating with the main passage 63 is formed on the left side wall 14b of the lower crankcase 14. The oil passage 65 opens on the mating surface 14a of the lower crankcase 14 and passes through the oil passage formed on the mating surface 14a. The passage 66 communicates with the housing portion 60 through the opening. Further, communication to the adjacent bearing 33 side is formed from the housing portion 60 . Mainly, (the mating surface of) the stepped portion 51 is provided with an oil leakage preventing groove 68 for returning lubricating oil supplied from these oil passages 65 , 66 , 67 into the crankcase 12 .

In the breather device of the present invention, the breather case 22 is disposed on the rear upper surface of the engine case, specifically, the rear upper surface of the transmission case 19 . As shown in FIG. 4 and the like, the vent box 22 has a substantially rectangular shape (planar view). As shown in the figure, the starter motor 18 is disposed behind the starter motor 18 , that is, between the front clutch shaft 25 and the breather case 22 .

Here, as shown in FIG. 6 , in the present embodiment, the crankcase 12 and the transmission case 19 communicate with each other in the engine case, and there is no partition wall or the like that separates them. There is an extremely limited space S between the crankshaft 25 in the crankcase 12 and the gear group 48 arranged on the countershaft 28 in the gearbox 19, and the two are arranged close to each other. This alone contributes to downsizing of the engine 11 .

Referring to FIG. 5( b ), in the vent box 22 , an arcuate or D-shaped leak gas blowing portion 70 is disposed on the right side (clutch device 36 side) of the vent chamber 69 . Corresponding to the air blowing portion 70, a leakage gas introduction passage 71 communicating from the right side wall 19b (see FIG. 11) of the transmission case 19 (specifically, the upper case 19A) to the breather chamber 69 is formed. That is, the clutch chamber side communicates with the breather chamber 69 through the leakage gas introduction passage 71 .

In addition, as shown in FIG. 9 , the breather case 22 is arranged on the rear upper surface of the transmission case 19 . In addition, as shown in the figure, the crankshaft 25, the countershaft 28 and the drive shaft 29 are arranged neatly on the upper and lower mating surfaces of the engine case. The upper part of the vent box 22 is covered with a vent cap 23 , and a hose 72 is connected to the vent cap 23 . As shown in FIG. 2 , this hose 72 extends upward and is connected to an air filter 134 . That is, the gas in the leakage gas separated into gas and liquid in the vent box 22 is sent to the air filter 134 through the hose 72 .

And, as shown in FIG. 11, a communication hole 73 is formed at the bottom of the right side wall 12c of the crankcase 12 (specifically, the crankcase lower part 14), and the communication hole 73 communicates with the crankcase 12 and the side wall 12c sandwiching the right side wall. Adjacent to the clutch chamber on the right side. Through this communication hole 73, the side of the crankcase 12 (and the gearbox 19) and the side of the clutch chamber are connected, that is, the leakage gas in the crankcase 12 is sent to the clutch chamber through this communication hole 73, and the leakage gas is passed through the leakage gas. The introduction passage 71 feeds from the clutch chamber to the breather chamber 69 .

Therefore, in the breather device of the present invention, as shown in FIG. 9 and the like, an oil return passage 74 communicating with the breather case 22 is formed on the rear wall of the engine case. The blow-by gas is introduced from the crankcase 12 to the breather case 22 to separate the gas and liquid, and the separated oil is returned to the storage part (that is, the oil pan 24 ) through the oil return passage 74 .

Specifically, the oil return passage 74 is integrally formed on the rear wall 19c of the transmission case 19 constituting a part of the engine case so as to protrude toward the inner side of the rear wall 19c. Although in the rear wall 19c of the transmission case 19 (the upper case 19A and the lower case 19B), the oil return passage 74 is formed in the vertical direction, but as shown in FIG. 6 or FIG. The front side, that is, does not protrude toward the rear. The upper end of the oil return passage 74 opens into the breather chamber 69 , and, as shown in the example of FIG.

As described above, there is only a limited space S between the crankcase 12 and the transmission case 19, and therefore it is not possible to substantially provide a partition wall at this location. As described above, the size of the engine 11 can be reduced especially in the front-rear direction by not providing a partition wall at this location. While being miniaturized, the oil after gas-liquid separation can be returned to the oil pan 24 through the oil return passage 74 provided on the rear wall 19c of the transmission case 19 as described above. In this case, by making the oil return passage 74 protrude toward the inner side (front side) of the transmission case 19 instead of protruding rearward, the engine case can be arranged without intentionally moving the front side, so that the oil return passage 74 and the The engine 11 is arranged at an optimum position where the vehicle body frame 101 does not interfere.

In addition, as described above, when the oil return passage 74 is formed, it is arranged correspondingly to a transmission gear having a non-largest diameter among the transmission gears arranged in line in the transmission case 19 . For example, as shown in FIG. 6 or FIG. 7 , it is formed and arranged to correspond to the smallest-diameter gear 49A in the gear group 49 on the drive shaft 29 side.

By arranging in correspondence with the gear 49A having the smallest diameter in this way, it is possible to effectively reduce the size of the engine case while preventing mutual interference. In this regard, when arranging to correspond to a large-diameter transmission gear, the oil return passage 74 has to be arranged away from the breather chamber 69 (backward in the example of FIG. 9 and the like) due to the increase in diameter. In this case, it is necessary to provide a horizontal (horizontal communication hole) for connecting the upper end of the oil return passage 74 to the breather chamber 69, and to insert a deadbolt into the opening of the communication hole (refer to FIG. 12). When the gear 49A with the smallest diameter as shown in FIG. 6 or FIG. 7 is arranged correspondingly with the gear 49B with a larger diameter, in order to avoid interference with the gear 49B, it is necessary to retreat the oil return passage 74, and the retreat of the oil return passage 74 The amount will increase the size of the gearbox.

In addition, in the above case, the starter motor 18 is mounted between the crankshaft 25 and the breather case 22 and on the upper surface of the engine case. That is, the breather box 22 is arranged behind the starter motor 18 .

A starter motor 18 as a starting device of the engine 11 has a function of imparting driving force to the crankshaft 25 , and therefore is basically arranged at the closest position to the crankshaft 25 . On the other hand, especially for a parallel 2-cylinder engine with a relatively small displacement like this embodiment, the width dimension of the engine case in the left-to-right direction should be reduced, and the starter motor 18 and the breather case 22 should be arranged side by side. up is difficult. In contrast, as described above, the crankshaft 25 , the countershaft 28 , and the drive shaft 29 are arranged in a row along the horizontal plane to secure the length of the upper surface of the engine case (gearbox 19 ) in the front-rear direction. Thus, the starter motor 18 and the breather box 22 are arranged in front and back on the upper surface of the engine case, the engine can be miniaturized, and the appropriate arrangement relationship with the surrounding auxiliary machinery can be maintained, making the breather box 22 a better arrangement structure.

Although the oil return passage 74 is arranged correspondingly to the non-largest-diameter speed gear among the speed change gears as described above, in other words, it is configured to overlap with at least one speed change gear arranged in a row in the transmission case 19 when viewed from the side, and when the speed change In the region between the bearings provided on both side walls of the case 19, the transmission gears are sandwiched between each other.

For example, as shown in FIG. 6 or FIG. 7 , a gear 49B having a larger diameter than the gear 49A is disposed adjacent to the gear 49A having the smallest diameter provided corresponding to the oil return passage 74 . As shown in FIG. 10 , the oil return passage 74 overlaps with the gear 49B when viewed from the side. In addition, as shown in FIG. 7 and the like, in the area between the bearing 32 and the bearing 33 of the drive shaft 29 , the oil return passage 74 is sandwiched between the large-diameter gear 49B and gear 49C adjacent to the gear 49A.

As described above, on the rear wall of the transmission case 19, the oil return passage 74 is arranged as close as possible by effectively utilizing the space formed between the gear groups 49, whereby the size and weight of the engine can be reduced, and thus the Reduce fuel costs and improve vehicle maneuverability. Furthermore, not only the engine, but also the entire vehicle body can be reduced in size and weight, and operational stability can be improved. In addition, since redundant components for forming the oil return passage 74 and processing for these components are not required, the processing and assembly steps can be reduced, and the cost can be further reduced.

As mentioned above, although this invention was demonstrated together with various embodiment, this invention is not limited to these embodiment, Change etc. can be implemented within the scope of this invention.

In the above-mentioned embodiment, the gear groups 48 and 49 arranged in the transmission case 19 are not limited to the configuration shown in the illustration, and other configurations are also possible.

Claims (5)

1. the air-breather of a motorcycle engine, this motorcycle engine has engine case, and this engine case comprises crankcase that disposes bent axle and the gearbox that disposes a plurality of speed change gears, and this air-breather is characterised in that, comprising:

Vent box, it is disposed at the rear upper surface of said engine case;

Way to cycle oil, it is formed at the rear wall of said engine case, is communicated with said vent box,

Wherein, said vent box is directed to said vent box with gas leakage from said crankcase and carries out gas-liquid separation, and separated oil is refluxed to food tray through said way to cycle oil.

2. the air-breather of motorcycle engine as claimed in claim 1; It is characterized in that; Said crankcase and said gearbox form in said engine case and are interconnected; And said way to cycle oil is formed on the rear wall of said gearbox of a part that constitutes said engine case, and side-prominent in said gearbox.

3. according to claim 1 or claim 2 the air-breather of motorcycle engine is characterized in that the gear mesh of non-maximum diameter should dispose in all speed change gears of being arranged in said way to cycle oil and the said gearbox.

4. the air-breather of motorcycle engine as claimed in claim 3; It is characterized in that; Also have the actuating motor that is installed on the said engine case upper surface, this actuating motor is configured in between upwardly extending cylinder of said engine case and the said vent box.

5. the air-breather of motorcycle engine as claimed in claim 3 is characterized in that, it is overlapping to see that from the side said way to cycle oil is configured to and is arranged at least one interior speed change gear of said gearbox.

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