JP2002213216A - Parallel four cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively support a thrust force applied to a cam shaft and reduce a size of an engine. SOLUTION: In this parallel four cylinder engine for motorcycle in which a crankshaft 81 is arranged at a front of a crankcase 50 in a motorcycle width direction, a projection 105 for thrust receiving is provided integrally with a cam shaft 100. A cam shaft 100 is driven by the crankshaft 81 at one end thereof, and the projection 105 is formed at a one end side of the cam shaft 100 and is engaged only to a bearing cap 102 of the cam shaft 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a parallel four-cylinder engine used for a motorcycle.

[0002]

2. Description of the Related Art As a parallel four-cylinder engine for a motorcycle, for example, Japanese Unexamined Patent Publication No.
The one disclosed in JP-A-8-15010 is known. This parallel four-cylinder engine receives a thrust force applied to the camshaft by contacting a thrust receiving step provided on the camshaft with a thrust receiver provided on the cylinder head side. However, in a parallel four-cylinder engine having such a structure, since a thrust receiver is provided on a cylinder head disposed between cylinders, a dimension for providing the thrust receiver between the cylinders is required, and there is a limit in reducing the cylinder interval. There is. Also, since the center cam chain method is adopted, there is no idea to make the head and cylinder compact,
Such a structure has a problem that the engine cannot be made compact.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a parallel four-cylinder engine capable of effectively supporting a thrust force applied to a camshaft and reducing the size of the engine. The purpose is.

[0004]

According to a first aspect of the present invention, there is provided a parallel four-cylinder engine for a motorcycle having a crankshaft arranged in a vehicle width direction in front of a crankcase. A parallel four-cylinder engine, comprising a thrust receiving ridge integrally with a camshaft, wherein the camshaft is driven by a crankshaft at one end thereof, and the ridge is formed at the one end of the camshaft. And the camshaft is engaged only with the bearing cap of the camshaft.

[0005] In the parallel four-cylinder engine according to the second aspect of the present invention, in the parallel four-cylinder engine according to the first aspect, the bearing cap is integrally formed as a bearing cap of a camshaft in at least two cylinders on the one end side. It is characterized by being molded.

According to the parallel four-cylinder engine according to the present invention, by driving the camshaft at one end of the crankshaft, it is possible to reduce the dimensions of the crankshaft, the cylinder and the cylinder head along the longitudinal direction of the crankshaft. It becomes possible. Further, since the protrusion provided integrally with the camshaft is formed on one end side of the camshaft and is engaged with the bearing cap, the position where the thrust force is supported is not restricted between the cylinders. Therefore, it is possible to receive a thrust force at a position close to the torque applied to one end of the camshaft.

Further, the upward force applied to the camshaft can be effectively supported by the bearing cap. Further, since there is no need to provide a thrust receiver for receiving the thrust force of the camshaft on the cylinder head side, it is possible to easily make the cylinder and the cylinder head compact.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a parallel four-cylinder engine mounted on a motorcycle will be described below with reference to the accompanying drawings. In the explanation,
The directions such as front and rear and left and right are directions with respect to the vehicle body. FIG. 1 is a side view of the motorcycle 1, and FIGS. 2 and 3 are front views.

The motorcycle 1 includes a body frame 2 and
A pair of left and right front forks 3 rotatably supported by the front end of the body frame 2;
A steering wheel 4 attached to the upper end of the vehicle, a front wheel 5 rotatably supported by the front fork 3, a rear fork 6 swingably supported by the body frame 2,
A rear wheel 7 rotatably supported by the rear end of the rear fork 6, a water-cooled engine 8 according to the present invention supported by the body frame 2, and a radiator 9 also supported by the body frame 2; A fuel tank 10 disposed above the vehicle body frame 2, a seat 11 disposed behind the fuel tank 10 on which a driver and an occupant are seated, steps 12 and 13 for the driving vehicle and the occupant, A retractable stand 14 for supporting the vehicle body in an upright state when parking is provided. Almost the entire vehicle body is covered by a cowling 15 shown in FIG.

The vehicle body frame 2 includes a front end head pipe 16, a front engine hanger 17 a and a rear engine hanger 17 b which extend left and right from the head pipe 16, extend rearward and obliquely downward, and extend forward and backward.
Are integrally formed, a pair of left and right main frames 17 having hollow cross sections, a head pipe 16 and a front engine hanger 1.
A gusset pipe 18 is connected to the main frame 17 and a pair of left and right upper rails 19a and 19b are connected to the rear end of the main frame 17 and extend rearward and obliquely upward. And a seat rail 19. A battery D is accommodated in the front space between the left and right seat rails 19 and below the seat 11.

The step 12 for the driver is carried out through the step bracket 20 through the rear engine hanger 17b.
The step 13 for the occupant is fixed to the lower seat rail 19b via a step bracket 21, and the stand 14 is attached to the lower engine hanger 17b. A lower bridge 2 is provided at the lower end of the head pipe 16 of the body frame 2.
A steering stem (not shown) integrally provided with the steering stem 2 is rotatably inserted around an axis, and a top bridge 23 is fixed to an upper end protruding from the head pipe 16 of the steering stem.

The front fork 3 includes a bottom case 24 and a cushion (not shown).
The inner tube 25 is slidably inserted through the inner tube 25. The inner tube 25 is inserted and fixed to both left and right ends of the top bridge 23 and the lower bridge 22, respectively. As a result, the front fork 3 is integrated with the steering stem via the top bridge 23 and the lower bridge 22 and is rotatable.

The handles 4 are a pair of left and right, and the inner ends are fitted and fixed to the upper ends of the front forks 3 projecting from the top bridge 23, respectively. The front wheel 5 is formed by mounting a tire 27 on an outer periphery of a wheel 26 having an axle 26a provided at an axis.
Both ends of the axle 26a are supported by the lower end of the bottom case 24 of each front fork 3. In addition, a front fender 28 that covers an upper part of the front wheel 5 is attached to the left and right bottom cases 24.

On both left and right sides of the wheel 26 of the front wheel 5, a rotor 30 constituting a front disc brake device 29 is provided.
Are fixed coaxially and integrally with the wheel 26. The front disc brake device 29 is provided with the rotor 30
The rotor 3 is fixed to the rear side of the bottom case 24 of each front fork 3 via a stay 31 in an operating state.
The brake caliper 32 includes a brake caliper 32 that brakes the rotation of the brake caliper by frictional force with a zero interposed therebetween, and a brake lever 33 attached to the right handle 4 to operate the brake caliper 32.

The rear fork 6 has a base 3 at its front end.
A pair of left and right forks 35 extend rearward from the base 4. The base 34 is pivotally supported by a pivot 36 provided between the rear engine hangers 17 b of the main frame 17, thereby pivoting the pivot 36. The fork 35 can swing up and down. The fork 3
5, a triangular bulge 35a is attached to the upper part,
A rear fender 37 that covers an upper part of the front portion of the rear wheel 7 is integrally attached to the bulging portion 35a.

The rear wheel 7 has a slightly larger diameter than the front wheel 5 and, like the front wheel 5, is provided with a tire 39 mounted on the outer periphery of a wheel 38 provided with an axle 38a at an axial center. Are supported by the rear end of the fork portion 35 of the rear fork 6 so as to swing together with the rear fork 6.

The swinging of the rear wheel 7 from the road surface is buffered by the rear cushion unit 40. The rear cushion unit 40 is composed of a damper 41a, a spring 41b, and the like. The upper end of the cushion body 41 is pin-connected to a cross member (not shown) fixed between the left and right main frames 17, and the lower end of the cushion body 41. The first link 42 has one end connected to a pin and a cross member (not shown) provided between the other end of the first link 42 and the lower end of the left and right rear engine hanger 17b. And a second link 43 which is pin-connected.

The rear wheel 7 is also provided with a rear disk brake device including a rotor and a brake caliper, similar to the front disk brake device 29 of the front wheel 5, but the description thereof is omitted here. On the left side of the wheel 38 of the rear wheel 7, a sprocket 44 is fixed coaxially with the wheel 38, and a drive chain 45 described later is wound around the drive sprocket 44.

As shown in FIGS. 5 to 7 and the like, the engine 8 includes a cylinder block 49 comprising a cylinder block body 46, a cylinder head 47 and a cylinder head cover 48, and a crank provided below the cylinder block 49. This is a parallel four-cylinder four-cycle engine including a case 50 and four cylinders (cylinders) 51 arranged in parallel in a left-right direction in a cylinder block 49.
In the engine 8, the cylinder block 49 is inclined slightly forward, and the front portion of the cylinder block 49 is connected to the front engine hanger 17 a of the main frame 17.
The rear side is connected to the main frame 17 via the stay 52,
The rear part of the crankcase 50 is the rear engine hanger 1.
7b is supported by the vehicle body frame 2 by being bolted to each.

At the rear of the cylinder block 49 of the engine 8, the cylinder block 4
A carburetor 53 for supplying an air-fuel mixture into 9 is connected,
Further, an air cleaner 54 is connected to the carburetor 53. The air cleaner 54 is disposed in a recess 10 a formed on the front lower surface of the fuel tank 10. An intake pipe 55 that is bent downward is connected to a front portion (upstream side) of the air cleaner 54, and an intake port 53a of the carburetor 53 is inserted into a rear portion.

An exhaust pipe 56 is connected to the front of the cylinder block 49 for each cylinder 51. As shown in FIG. 2, the first exhaust pipes 56a, 2
No. exhaust pipe 56b, No. 3 exhaust pipe 56c, No. 4 exhaust pipe 56d
These four exhaust pipes 56 extend downward from the connection end to the cylinder block 49 and are aligned below the engine 8, and are further bent and bent.
It extends rearward along the lower surface of the crankcase 50 and is integrated into one collecting pipe 57 at the lower rear part of the crankcase 50. The collecting pipe 57 is routed to the right side of the rear wheel 7 while rising diagonally right rearward, and a cylindrical silencer 58 extending diagonally upward is mounted at the end of the collecting pipe 57. The engine 8 will be described later in detail.

The radiator 9 is of a horizontally long rectangular cross-flow type in which a cooling water inflow tank (both not shown) is connected to the right side of the core and an outflow tank 9a is connected to the left side. In this state, it is disposed in front of the engine 8 and is supported by the front engine hanger 17 a and the gusset pipe 18. Immediately behind the radiator 9, a radiator fan 9 for cooling the radiator 9 is provided.
A is equipped. Also, in front of the radiator 9,
An alarm 59 is provided. The alarm 59 is attached to the front engine hanger 17a via stays 60 and 61.

As shown in FIGS. 1 to 4, the cowling 15 covers a front cowl 62 whose front end surface is along the main frame 17 and a portion below the fuel tank 10 and the seat 11. A rear cowl 63 covers the rear of a vehicle body, and a front cowl 62
Is divided into an upper cowl 64, a middle cowl 65 and an under cowl 66.

The upper cowl 64 of the front cowl 62
Is formed in a streamline shape from the front to the rear of the head pipe 16 and covers both sides of the upper part of the front fork 3 and both sides of the radiator 9 and the cylinder block 49 of the engine 8. A notch 64a for avoiding interference with the handle 4 is formed, and a substantially U-shaped notch 64b when viewed from the front is formed at the upper end of the front portion. A transparent screen 67 that extends to bend substantially to the upper side and covers the upper part of the front fork 3 is provided integrally. The upper cowl 64 has a front end supported by a cowl stay (not shown), and a side portion bolted to the main frame 17 and the front engine hanger 17a.

As shown in FIG. 2 and the like, on the left and right sides of the front portion of the upper cowl 64, there are formed air inlets 68 for introducing the traveling wind to the radiator 9, and a center between the air inlets 68 is formed. , A headlight 69 is arranged, and an air inlet 70 is formed above the headlight 69. A meter unit 71 to which a speedometer, an engine tachometer, and the like are attached is disposed inside the upper cowl 64. This meter unit 71
The head pipe 16 is attached via a stay 72. Further, direction indicators 73 are attached below the left and right air introduction ports 68 of the upper cowl 64, respectively.

Middle cowl 65 of front cowl 62
The upper cowl 64 is formed in a shape conforming to the notch 64c at the rear of the upper cowl 64. The upper cowl 64 and the under cowl 66 are located on the rear side of the engine 8.
It is bolted to. At the front end of the middle cowl 65, an exhaust port 65a for discharging air introduced into the cowling 15 to the outside is formed.

Under cowl 66 of front cowl 62
Has a U-shaped cross section, continuously covers both sides of the crankcase 50 of the engine 8 and the exhaust pipe 56 from the lower end of the upper cowl 64, and is bolted to the main frame 17. An air inlet 66 for introducing a traveling wind into the under cowl 66 is provided at a lower front portion of the under cowl 66.
a is formed.

The rear cowl 63 is formed so as to cover the side of a seat rail 19 composed of two upper rails 19a and two lower rails 19b on the left and right sides. And are attached to the rails 19a and 19b by fitting means such as hooks. A rear fender 74 that covers an upper rear portion of the rear wheel 7 is attached to a rear end of the rear cowl 63. Further, two exhaust ports 63 for exhausting the air in the rear cowl 63 to the outside are provided at the front part thereof.
b, 63c are formed.

Next, the engine 8 will be described in detail with reference to FIGS. The engine 8 includes a cylinder block body 46 and a cylinder head 47 as described above.
And a cylinder block 49 including a cylinder head cover 48 and a crankcase 50. The crankcase 50 is formed by integrally joining an upper case 50a and a lower case 50b so that the upper case 50a and the lower case 50b can be divided. Have been. Further, an oil pan 75 is joined below the lower case 50b. A crankshaft 81 is disposed at the front of the crankcase 50 in the vehicle width direction, and a transmission 131 and a clutch mechanism 144 are disposed at the rear of the crankcase 50.
Is arranged.

As shown in FIG. 7, the cylinder block 49
, Four cylinders 51 are arranged in parallel, and a piston 77 is slidably fitted in these cylinders 51 via a casting sleeve 76. These pistons 7
The chain sprocket 7 is rotatably supported in the crankcase 50 via a connecting rod 78 and is provided at one end (in this case, the right end: the end on the side where the clutch mechanism 144 exists).
9 is connected to a crankshaft 81 in which an oil groove 80a for supplying lubricating oil is formed on the peripheral surface of the journal portion 80. The rotation of the crankshaft 81 causes the cylinder 5 to rotate.
1 to reciprocate up and down. As shown in FIG. 5, the connecting rod 78 is formed with an oil hole 82 for sending the lubricating oil flowing through the oil groove 80a to the lower surface of the piston 77. The oil hole 82 linearly extends from the upper surface of the large end 78a of the connecting rod 78 in a direction slightly deviated toward the piston 77 from the center of the large end 78a.

As shown in FIG. 5, the cylinder head 47 is provided with combustion chambers 83 each formed by the cylinder head 47 and each piston 77 reaching the top dead center. Spark plug 8
4 are further screwed in, and further, an intake passage 85 and an exhaust passage 86 that communicate each combustion chamber 83 with the outside are formed.

As shown in FIG. 9, the intake passage 85 is connected to a combustion chamber 83 of one cylinder 51 via a main intake passage 85A which opens to the outside and a branch portion 85B.
The branch passages 85a and 85b are formed to branch into two, and each of the branch passages 85a and 85b communicates with the combustion chamber 83, respectively, and these two openings serve as intake ports 87a and 87b, respectively. .

Further, two exhaust ports, which are openings of the exhaust passage 86 to the combustion chamber 83, are formed for one combustion chamber 83. That is, the exhaust passage 86 is formed by two main branch passages 86A formed by two branch passages 86a and 86b communicating with the combustion chamber 83 via the gathering portion 86b, and each branch passage 86a and 86b is opened to the combustion chamber 83. Are exhaust ports 88a and 88b, respectively.

FIGS. 8 and 9 show the cylinder head 47.
As shown in the figure, an intake valve 89a for opening and closing the intake ports 87a and 87b and the exhaust ports 88a and 88b,
89b and exhaust valves 90a and 90b are provided respectively. As shown in FIG. 8, each of the intake valves 89a and 89b has a valve stem 91 having an umbrella-shaped valve body 91a that actually opens and closes each of the intake ports 87a and 87b, and biases the valve stem 91 upward. A valve spring 9 for closing the intake ports 87a and 87b with the valve body 91a closed
2 and a cylindrical valve lifter 93 mounted on the upper end of the valve stem 91. The valve stem 91 is slidably inserted into a valve guide 94 fitted to the cylinder head 47.

The exhaust valves 90a and 90b are the same as the intake valves 89a and 89b, and include a valve stem 95 having a valve body 95a, a valve spring 96, a valve lifter 97, a valve guide 98, and the like.
On the cylinder head 47, each intake valve 89a, 89
b, an intake-side camshaft 99 and an exhaust-side camshaft 100 for operating the respective exhaust valves 90a and 90b are arranged in parallel with the crankshaft 81.

These camshafts 99 and 100 are hollow, and the cylinder head 4 is
7 is rotatably supported around an axis by a bearing cap 102 fixed to the intake cams 103a, 103b corresponding to the intake valves 89a, 89b and the exhaust valves 90a, 90b. Cam 104
a and 104b are formed integrally with each other, and further, a ridge 105 that engages with the bearing cap 102 and regulates movement in the axial direction is formed integrally with the right end. The hollow portion of each of the camshafts 99 and 100 is a passage for lubricating oil, and an oil hole 220 communicating with this passage is provided.
Are formed from the base surface of each of the cams 103a, 103b, 104a, 104b to the hollow portion.

At the right ends of the camshafts 99 and 100, cam sprockets 106 and 107 are provided integrally, respectively. A cam chain 108 is wound around the cam sprockets 106 and 107 and the chain sprocket 79 of the crankshaft 81. The rotation of the crankshaft 81 causes each of the camshafts 99 and 100 to rotate.
Is designed to rotate.

The camshafts 99, 100
Are rotated, the intake cams 103a, 103b
The peripheral surfaces of the exhaust side cams 104a and 104b correspond to the respective intake valves 89a and 89b and the respective exhaust valves 90a and 89b.
The valve stems 91 and 95 reciprocate up and down by slidingly contacting the valve lifters 93 and 97 a and 90b, whereby the intake ports 87a and 87b and the exhaust ports 88a and 88b open and close.

As shown in FIG. 8, a lubricating oil reservoir 47b, which is a recess, is formed around each of the valve lifters 93 and 97 in the cylinder head 47. And the valve lifter 93,
When the valve 97 moves downward, the valve lifters 93 and 97 and each cam 1
Lubricate sliding with 03a, 103b, 104a, 104b. In FIG. 8, the dashed line is a horizontal line in a state where the engine 8 is mounted on the vehicle body (the vehicle body frame 2). As shown in FIG. 10, oil holes 4 for returning lubricating oil to oil pan 75 are provided at both ends of cylinder head 47.
7c is formed.

As shown in FIG. 6, a cam chain tensioner 109 for suppressing flapping of the cam chain 108 is provided on the outer peripheral side of the cam chain 108 between the cam sprocket 106 and the chain sprocket 79 of the intake cam shaft 99. Is arranged. The cam chain tensioner 109 has one end connected to the cylinder head 47 by a pin and is swingable, and the tensioner slipper 110 extends along the cam chain 108;
a, and is fitted in a piston holder 111 disposed in the cylinder block body 46, and the swing end of the tension slipper 110 is always moved by hydraulic pressure to the cam chain 10.
8 against the piston 112.

As shown in FIG. 6, a cam chain guide 221 is mounted on the cylinder head cover 48 on the outer periphery of the cam chain 108 between the cam sprockets 106 and 107.

As shown in FIG. 5, the carburetor 53 is connected to the outside opening of the intake passage 85 (main intake passage 85A) by a cab insulator 113, and the exhaust passage 86 (main exhaust passage The connection end of the exhaust pipe 56 is connected to the opening 86A on the outside.

The cylinder head cover 48 joined to the cylinder head 47 communicates with the crankcase 50 via a cam chain chamber 108a in which the cylinder head cover 48 and the cam chain 108 are arranged. A breather chamber 114 is provided for separating oil contained in blow-by gas generated therein. The blow-by gas from which oil has been separated in the breather chamber 114 is discharged to the atmosphere from an air guide tube 115 connected to the breather chamber 114.

As shown in FIGS. 6 and 7, the right end of the crankshaft 81 is
1 and a generator cover 117 fixed to cover the crankcase 50
Further, an ignition timing detection mechanism 119 including a pulse generator 118 supported at a position radially outward of the pulsar rotor 116 is provided.

On the left end of the crankshaft 81,
A rotor 120 that rotates integrally with the crankshaft 81,
An AC generator 123 including a stator 122 supported by an AC generator cover 121 fixed to the crankcase 50 is provided. The AC generator cover 121 protrudes slightly outward from a circular opening 66b (see FIG. 4) formed in the under cowl 66 of the front cowl 62. The upper space of the AC generator cover communicates with a lubricating oil passage 46b formed in the cylinder block main body 46. From the lubricating oil passage 46b, a space above a guide rib 121a formed on the inner surface of the AC generator cover 121 is formed. AC through
Lubricating oil is supplied to the sliding portion of the generator cover 123.

Further, the AC generator cover 12
A starter motor driven sprocket 125 is mounted on the crankshaft 81 inside the cylinder 3 via a needle bearing 124. The starter motor driven sprocket 125 is connected to the inner periphery of a ring 120a fixed to the rotor 120 via a one-way clutch 126, and is disposed on the left side in the upper case 50a of the crankcase 50. The drive shaft 127 is connected to gears 129 and 130 via gears 129 and 130. The ring 120a has a plurality of oil holes 120b that serve as passages for lubricating oil along the circumferential direction (FIG. 7).
Only one is visible).

Next, the transmission 131 connected to the engine 8 and the change mechanism 132 for switching and controlling the transmission 131 will be described.

As shown in FIG. 7, the transmission 131 is mounted on a transmission case 133 integral with the lower case 50b of the crankcase 50 in parallel with the crankshaft 81 and with the needle bearings 134 and 135 and the ball bearings 136, A hollow main shaft 138 and a counter shaft 13 rotatably disposed via
9 (both spline shafts) and both shafts 13
8, 139 provided on the right end of the main shaft 138 and meshing with the primary drive gear 142 of the crankshaft 81, and a main driven gear 143 provided on the right end of the main shaft 138. 138, a clutch mechanism 144 provided at the right end.
And a clutch mechanism 144 provided at the right end of the main shaft 138, a clutch release 145 inserted through the main shaft 138 so as to be movable in the axial direction, and intermittently connecting and disconnecting the clutch mechanism 144.

Each of the main shaft 138 and the counter shaft 139 is hollow, and the inside thereof is provided with lubricating oil supply passages 146 and 147, respectively.
46, 147 to the outer peripheral surface, the transmission gear group 140a
To 140f and 141a to 141b, clutch mechanism 1
Oil holes 148 and 149 for supplying lubricating oil to 44 are formed, respectively.

According to the transmission 131, the power of the engine 8, that is, the rotation of the crankshaft 81 is transmitted to the main shaft 138 via the primary driven gear 143 and the clutch mechanism 144, and subsequently, the transmission gear groups 140a to 140f , 141a to 141f are transmitted to the countershaft 139, and further transmitted from the driven sprocket 150 fixed to the left end of the countershaft 139 to the rear wheel 7 via the drive chain 45.

The primary driven gear 143 is
It consists of a main gear 143a and a sub gear 143b,
Although the gears 143a and 143b are relatively rotatable, the rotation thereof is restricted by a damper spring 151 so that backlash in meshing with the primary drive gear 142 is suppressed. The main shaft 138 is attached to the main shaft 138 so as to be rotatable relative to the main shaft 138. An oil pump drive sprocket 154 that rotates integrally with the primary driven gear 143 is fitted to the sleeve 152. The oil pump drive sprocket 154 is connected to an oil pump 156 described later by a chain 155.

Next, the clutch mechanism 144 will be described. As shown in FIG. 7, this clutch mechanism 144 is provided with a clutch outer 157 riveted to the primary driven gear 143 and housed in the clutch outer 157. A clutch center 158 that rotates integrally with the main shaft 138;
57 and the friction plate 157a on the clutch center 158 side
, 158a, and both friction plates 157a, 158
a. Clutch pressure plate 1 for alternately pressing
59 and the like.

The clutch pressure plate 159 is rotated integrally with the clutch center 158 by the bolt 160 and is movable in the axial direction of the main shaft 138, but is always urged outward (to the right in FIG. 7) by the clutch spring 161. In this state, the two friction plates 157a, 158a are pressed against each other, and the clutch mechanism 144 is brought into the connected state. When the clutch pressure plate 159 is moved rightward by the operation of the clutch release 145, the friction plate 157a
58a is released and the clutch mechanism 144 is disconnected.

A clutch release 145 is fixed to the transmission case 133 and is set on a clutch cover 162 that covers the clutch mechanism 144 so as to be rotatable around an axis. The rotation of the release shaft 163 causes the main shaft to rotate. 138 is movable in the axial direction, and its tip is connected to the center of a clutch spring 161 via a ball bearing 164 via an operating rod 16.
5, a release lever 166 fixed to the lower end of the release shaft 163, a return spring 167 for controlling the rotation of the release shaft 163, and the like. The release lever 166 is a clutch lever 168 mounted on the left handlebar 4. Is connected to a clutch wire (not shown).

When the clutch wire is operated (pulled) by the clutch lever 168, the release shaft 163 is rotated via the release lever 166, and at the same time, the operation rod 165 moves to the left, and the clutch mechanism 144 is moved. Is turned off.

The change mechanism 132 for switching and controlling the transmission 131 will be described.
As shown in FIG. 7, a change spindle 169 rotatably supported by the transmission case 133 and a plurality of cam grooves 170a formed on the outer periphery are rotatably mounted on the transmission case 133 via ball bearings 171. A shift drum 170 supported on the shift drum 170 is disposed at one end of the shift drum 170 and rotates integrally with the shift drum 170. A shift pin 172a is radially provided at the end of the shift drum 170, and an engagement recess 17 is provided at the periphery.
2b, a shift plate 173 fixed to the right end of the change spindle 169 and an engaging portion 173a provided at the tip engages with a shift pin 172a of the shift drum center 172, and a transmission case 133. The shift drum 17 is fixed and its front end is engaged with the engagement recess 172 b of the shift drum center 172.
A stopper plate 174 for restricting the rotation angle of 0 and a shift fork shaft 175 supported on the transmission case 133 are slidably mounted in the axial direction of the shift fork shaft 175, and one end of the shift
0 of the main shaft 138 and the counter shaft 139 of the transmission gears 140a to 140a.
40f, and a plurality (three in this case) of shift forks 176 which are appropriately engaged with 141a to 141f. Change spindle 169, shift drum 17
The shift fork shaft 175 is disposed in parallel with the main shaft 138 and the counter shaft 139 of the transmission 131, respectively.

A change pedal (not shown) is spline-fitted to the protruding end of the change spindle 169 from the transmission case 133.
9 is rotated by a fixed angle, this rotation is transmitted to the shift drum 170 via the shift plate 173 and the shift drum center 172, and each shift fork 176 is appropriately slid by the rotation of the shift drum 170. The engagement between the transmission gears 140a to 140f and the transmission gears 141a to 141f can be changed as appropriate.

A driven sprocket cover 177 that covers the driven sprocket 150 at the end of the counter shaft 139 is fixed to the transmission case 133. The driven sprocket cover 177 has a back plate 177b fixed to the back side of the cover body 177a by ultrasonic welding.

The sliding portions of the engine 8 and the transmission 131 having the above-described structure are lubricated by a lubricating oil supply device 178 provided below the engine 8. As shown in FIGS. 5, 6, and 11, the lubricating oil supply device 178 is integrally fixed to a lower portion of the lower case 50b of the crankcase 50 and has a lubricating oil L therein.
Oil pan 75 for storing oil, an oil strainer 179 immersed in lubricating oil L, and an oil strainer 17 mounted in a crankcase 50 through a pipe 180.
9 and an oil filter 182 fixed to the front of the crankcase 50 and connected to the oil pump 156 via a first oil passage 181.
And an oil relief valve 183 provided in the middle of the first oil passage 181 and immersed in the lubricating oil L.

The oil pump 156 is connected to the oil pump drive sprocket 154 of the main shaft 138 via the chain 155 as described above, and operates by the rotation of the engine 8 to suck the lubricating oil L from the oil strainer 179. The oil is sent from the pipe 180 to the oil filter 182 via the first oil passage 181. The lubricating oil L filtered through the oil filter 182 is supplied to the second oil passage 18 provided on the left side of the first oil passage 181 in the lower case 50b in parallel with the first oil passage 181.
4, while being cooled by passing through a cooling case 185 provided at the front of the lower case 50b.

As shown in FIGS. 12 to 15, the cooling case 185 is vertically elongated and has a case body 186 interposed between the crankcase 50 and the oil filter 182; And a lid 187 that covers and covers the front side of the 186.

FIG. 13 and FIG.
As shown in FIG. 7, flange portions 188a and 188b to which an oil filter 182 and a lid 187 are joined are formed on the outer periphery, respectively, and the first oil passage 18 is formed.
1 that communicates with the upstream side of the oil filter 182
189, a first inflow port 190 communicating with the downstream side of the oil filter 182, and a second outflow port 191 connected to the first inflow port 190 and rising obliquely upward to the front of the case body 186. A first oil passage pipe 192 that opens through the second oil passage pipe 192 and a second inlet 193 that is an opening to the second oil passage 184 are formed.
A cooling water port 194 is provided at an upper part thereof, and a connecting pipe 19 of a water pipe 195 communicating with a case body 186 is provided at a lower part thereof.
6 is connected. Here, the first oil passage pipe 192 functions as an oil connection passage connecting the cooling case (oil cooler) 185 and the oil filter 182, and the first oil passage pipe 192 is formed of a crankcase. 50 will be arranged in a straight line on the front side.

A second oil passage pipe 197 connecting the second outlet 191 and the second inlet 193 is connected to the front side of the case main body 186. This oil passage pipe 1
In the case 97, a flange portion 197 a integrally formed vertically is screwed to the case main body 186.

The outer peripheral flange portions 188a, 188
b has a through hole 19 for fixing to the crankcase 50.
8 and screws 199 for fixing the lid 187 are formed at appropriate locations. Of these, the lowest through hole 198
Is a drain for draining water.

On the other hand, as shown in FIG. 12, the lid 187 has a shape corresponding to the case main body 186 and has a box-like shape having an appropriate volume inside.
The flange 200 formed on the outer periphery is joined to the flange 188 b of the case main body 186 in the state facing.

The flange body 200 includes a case body 186.
A through-hole (not shown) corresponding to the through-hole 198 formed in the flange portion 188b and the screw hole 199 is formed by a screw (not shown) screwed into the screw hole 199 through the through-hole in the cover 187. Joined to the case body 186,
And the through hole 1 in the lid 187 and the through hole 1 in the case body 186.
The cooling case 185 is screwed into the crankcase 50 through a screw 98 (not shown).
Fixed to. The cooling case (oil cooler) 1
The oil case 85 and the oil filter 182 are arranged side by side on the front surface of the crankcase 50, and the mutually projecting tips of the cooling case 185 and the oil filter 182 are the crankcase 50 and the exhaust pipe 56 in front thereof. It is attached so that it is located in the space surrounded by.

The lubricating oil L passing through the cooling case 185
In the following description, the first oil passage 181 enters the oil filter 182 through the first outlet 189, is filtered by the oil filter 182, and then passes through the first inlet 190 to the first oil passage. Rises inside the pipe 192,
From the second outlet 191 into the second oil passage 197,
After descending in the second oil passage pipe 197, it enters the second oil passage 184 via the second inlet 193. As described later, circulating cooling water flows into the cooling case 185 from the water pipe 195 to cool the lubricating oil L passing through the second oil passage pipe 197.

The lubricating oil L that has entered the second oil passage 184 via the cooling case 185 flows from the second oil passage 184 into the transmission 131 (the main shaft 138, the main shaft 138, as shown in FIG. 6). Counter shaft 139, clutch mechanism 144, etc.). Further, a main gallery 201 communicating with the second oil passage 184 is provided in the lower case 50 b of the crankcase 50. The main gallery 201 extends in the left-right direction, and the lubricating oil L flowing into the main gallery 201 from the second oil passage 184 is supplied to the engine 8 (the crankshaft 81, the piston 7).
7, each camshaft 99, 100, etc.). In FIG. 6, reference numeral 202 indicates the route. Oil pump 1 disposed behind crankshaft 81
A first oil passage (oil passage) 181 that is led from the bottom of the crankshaft 81 to the front of the water-cooled engine through the lower part of the crankshaft 81, and the lubricating oil cooled by the cooling case 185 is supplied to a crankshaft such as a journal. The main gallery 201 to be delivered to each receiving part is provided in the crankcase 50 in a state of intersecting with each other, and the main gallery 201 is provided so as to be located higher than the first oil passage 181 (FIG. 6, see FIG. 11).

Further, as shown in FIG.
2 passing through the cam chain tensioner 10
9 is operated by hydraulic pressure. That is, the piston holder 111 constituting the cam chain tensioner 109 and the cylinder block body 46 are provided with:
An oil passage 203 through which the lubricating oil L flows from the path 202 into the piston 112 is formed, and the hydraulic pressure of the lubricating oil L always urges the piston 112 toward the tension slipper 110. Then, the lubricating oil L that has completed the lubricating action returns to the oil pan 75 and is stored therein, and is circulated again through the above-described path.

In the circulation of the lubricating oil L, for example, when the oil pressure of the lubricating oil L to be fed increases as the engine 8 (crankshaft 81) rotates at a high speed and reaches a certain oil pressure, as shown in FIG. Also, the oil relief valve 183 shown in FIG. 6 is operated so that an appropriate amount of the lubricating oil L passing through the first oil passage 181 is returned into the oil pan 75, and the oil pressure is adjusted so as not to rise any more. Has become.

This oil relief valve 183 is
Of the lubricating oil L is urged by a spring 205 into a bottomed cylindrical outer cylinder 204 formed in the body of the oil passage 181 so that the discharge port 204a is normally closed. When the lubricating oil L passing through the first oil passage 181 reaches a certain oil pressure as described above, the inner cylinder 206 is opposed to the spring 205 by the lubricating oil L. By moving, the discharge port 204a is opened and the lubricating oil L is discharged into the oil pan 75 from the discharge port 204a.

Next, a cooling system using the radiator 9 will be briefly described with reference to FIGS. 5, 6, and 10. FIG. Lower case 50 in crankcase 50
A water pump 207 that rotates in accordance with the rotation of the crankshaft 81 is disposed substantially at the left side of the center in FIG. b. The water pump 207 has a radiator hose 208 that communicates with the outflow-side tank 9 a of the radiator 9.
And a water pipe 195 connected to the cooling case 185. Also, the cooling case 185
The inside of the lid 187 communicates with a water jacket 46 a formed in the cylinder block main body 46 via a cooling water port 194 formed in the case main body 186.

Further, the cylinder head 47 is formed with a water jacket 47a which is continuous with the water jacket 46a of the cylinder block main body 46. As shown in FIG. Cooling water passage 2 provided in
09. A thermostat 209a is provided in the cooling water passage 209, and when the cooling water passing therethrough reaches a certain temperature or higher, the radiator fan 9A operates.

A radiator hose (both not shown) connected to the leading end of the cooling water passage 209 is connected to the inflow tank of the radiator 9. The above is the circulation path of the cooling water. The cooling water cooled by the radiator 9 is operated by the water pump 207, passes through the radiator 9 → the radiator hose 208 → the water pump 207, the water pipe 195, and the lid of the cooling water case 185. After cooling the lubricating oil L as described above, the engine 8 is cooled by passing through the water jackets 46a and 47a, and then returns to the radiator 9 from the cooling water passage 209.

Next, a secondary air supply device 210 for exhaust gas according to the present invention will be described below with reference to FIGS. 8, 9, 15 to 26. FIG. The secondary air supply device 210 is disposed in front of the engine 8, and is connected to a reed valve 211 connected to a downstream side of the air cleaner 54 via a secondary air supply pipe (not shown), and an exhaust passage 86 in each cylinder 51. , A secondary air supply passage 212 formed in one of the two branch passages 86a and 86b upstream of the collecting portion 86B, and a downstream side of the secondary air supply passage 212 and the reed valve 211. And a connection pipe 213 connecting the two.

Each secondary air supply passage 212 is connected to the right branch passage 86b in the first cylinder 51a and the third cylinder 51c, and to the left branch passage 86a in the second cylinder 51b and the fourth cylinder 51d. The cylinder head 47 extends from the front surface to the inside thereof.
The connection pipe 213 is connected.

Each connecting pipe 2 is provided inside the reed valve 211.
13 are formed, and a reed valve element (both not shown) is provided for each of these passages. When the engine 8 is in the operating state and the combustion chamber 8
3 passes through the exhaust passage 86, and thereby the inside of the secondary air supply passage 212 and the connection pipe 213.
The inside of each of the valve bodies is opened in a negative pressure state, and air (hereinafter referred to as secondary air) is supplied from the air cleaner 54 to the secondary air supply pipe via the secondary air supply pipe, the reed valve 211, and the connection pipe 213. From the passage 212, each branch passage 86a (or 86b)
It is supplied inside.

Incidentally, one cylinder 51 of the exhaust-side camshaft 100 of the engine 8 in the present embodiment.
When the exhaust valve 90a (or 90b) corresponding to the branch passage 86a (or the branch passage 86b) in which the secondary air supply passage 212 is formed is opened, the other exhaust valve 90b is opened. (Or 90a) is set slightly earlier than when the valve is opened.

That is, the exhaust valves 90a (90
Each exhaust side cam 104a (104b) that opens and closes b)
With respect to the other exhaust side cams 104b (104a), a small angle (for example, 2
~ 3 degrees) offset. Each exhaust-side cam 104a (104) shown by a symbol (a) in FIG. 19 and FIG.
b) are those. Therefore, the exhaust gas discharged from the combustion chamber 83 flows into the branch passage 86a (86b) on the side where the secondary air supply passage 212 is formed, instantaneously and quickly.
After that, it flows into another branch passage 86b (86a).

According to the secondary air supply device 210, as described above, when the engine 8 is operating and the exhaust gas generated in the combustion chamber 83 passes through the exhaust passage 86, the secondary air Inside the supply passage 212 and the connection pipe 21
3 is in a negative pressure state, each valve element is opened, and the secondary air is supplied from the air cleaner 54 to the secondary air supply pipe, the reed valve 211,
The air is supplied from the respective secondary air supply passages 212 into the respective branch passages 86a (86b) via the connection pipe 213.

When the secondary air is supplied to the branch passages 86a (86b), the branch passages 86a (86b) are supplied.
The exhaust gas flowing into b), that is, the combustion gas remaining in the exhaust gas immediately after being discharged from the combustion chamber 83 reacts with the supplied secondary air to burn (oxidize).

On the other hand, the unburned gas in the exhaust gas flowing into the branch passage 86a (86b) on the side where the secondary air supply channel 212 is not formed reaches the collecting portion 86B of the exhaust passage 86 when the unburned gas reaches the collecting portion 86B. The exhaust gas on this side comes into contact with the secondary air, but the unburned gas burns due to the supply of the secondary air in the adjacent branch passage 86a (86b), so that the temperature near the collecting portion 86B increases. And therefore not immediately after being discharged from the combustion chamber 83, but at the collecting portion 86B
, The unburned gas in the exhaust gas is sufficiently reacted with the secondary air to burn, and almost no unburned gas remains, and the exhaust gas is discharged to the exhaust pipe 56 and the muffler 58. It is discharged to the outside through.

That is, the unburned gas remaining in each of the exhaust gases flowing through the two branch passages 86a and 86b is effectively burned by the secondary air, and the exhaust gas purification efficiency is greatly improved. By the way, FIG. 23 is a diagram showing the opening / closing timing A of the exhaust valve at which the above-mentioned exhaust purification efficiency is obtained highest, and FIG. 24 is a diagram showing the opening / closing timing B of the exhaust valve at which the output is obtained most.
Is a normal intake system with a moderate exhaust purification efficiency and output characteristics.
It is a figure showing the timing C of an exhaust valve. These time shifts are as shown in the graph of FIG. Here, the exhaust valve 90a (in some cases, 90b) on the side where the secondary air supply passage 212 shown in FIG. 22 is formed is the timing A, and the other exhaust valves 90b (in some cases, 90a) are the timing A By setting each of the exhaust side cams 104a and 104b so as to open and close at B, an engine having optimum exhaust purification efficiency and output characteristics is obtained.

[0084]

According to the parallel four-cylinder engine according to the first aspect of the present invention, the dimension of the crankshaft, the cylinder and the cylinder head along the longitudinal direction of the crankshaft can be reduced while reliably supporting the thrust force applied to the camshaft. There is an effect that the size can be shortened and the cylinder interval can be shortened to achieve compactness.

According to the parallel four-cylinder engine according to the second aspect of the present invention, since the bearing cap is integrally formed for the cams of the two cylinders at one end of the camshaft, the positioning thereof is facilitated. This has the effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is an overall side view of a motorcycle to which an embodiment of the present invention is applied.

FIG. 2 is a front view of the motorcycle of FIG.

FIG. 3 is a front view similar to FIG. 2;

FIG. 4 is a side view of the cowling.

FIG. 5 is a partially sectional left view of the engine of the embodiment.

FIG. 6 is a right side view, partially in section, of the engine of FIG. 5;

7 is a longitudinal sectional view of the engine of FIG.

FIG. 8 is a side view of a cylinder head.

FIG. 9 is a schematic plan view of a cylinder head.

FIG. 10 is a partial cross-sectional plan view of the engine with a cylinder head cover removed.

FIG. 11 is a partially transparent rear view of the engine.

FIG. 12 is a partial front perspective view of the engine.

FIG. 13 is a front view of a case main body in the cooling case.

FIG. 14 is a rear view of the case body of FIG. 13;

FIG. 15 is a front view of a lower portion of the engine.

FIG. 16 is a front view of a cylinder head.

FIG. 17 is a partial cross-sectional side view of a cylinder head.

FIG. 18 is a side view of the reed valve.

FIG. 19 is a rear view of the exhaust-side camshaft.

FIG. 20 is a side view of the camshaft of FIG.

FIG. 21 is a side view of the camshaft of FIG. 19 on the opposite side to FIG. 20;

FIG. 22 is a schematic view of an exhaust passage.

FIG. 23 is a diagram illustrating exhaust valve timing when the exhaust gas purification efficiency is the highest.

FIG. 24 is a diagram illustrating exhaust valve timing having the highest output characteristic.

FIG. 25 is a diagram showing normal intake / exhaust valve timing.

FIG. 26 is a graph showing a time lag between the exhaust timings of FIGS. 23 to 25.

[Explanation of symbols]

1 ... motorcycle, 8 ... (water-cooled 4-cylinder) engine 50 ... crankcase,
78 connecting rod, 79 chain sprocket, 81 crankshaft, 108 cam chain, 116 pulsar rotor, 1
18: pulse generator 131: transmission 138: main shaft 142:
Primary drive gear, 143 primary driven gear, 144 clutch mechanism, 154 oil pump drive sprocket, 155 chain
156 ... oil pump.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Mizuno 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G016 AA02 AA08 AA12 AA19 BA03 BA06 BA19 BA23 BA28 BA32 CA07 CA11 CA16 CA23 CA33 GA01 3G024 AA18 AA19 BA05 DA01 DA06 DA10 DA18 EA03 FA13

Claims (2)

[Claims] 1. A parallel four-cylinder engine for a motorcycle having a crankshaft arranged in a vehicle width direction at a front part of a crankcase, comprising: a thrust receiving projection integrally formed with a camshaft; A four-cylinder engine in which the protrusion is formed on one end of the camshaft and is engaged only with a bearing cap of the camshaft. 2. The parallel four-cylinder engine according to claim 1, wherein said bearing cap is integrally formed as a bearing cap of a camshaft in at least two cylinders on said one end side.