JP2003328854A - Valve system for scooter type motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve system for a scooter type motorcycle having surely improved foot-straddling performance and maintainability by preventing a cam chain adjuster from being protruded upward from a cylinder and therefore preventing a main frame from being protruded upward. <P>SOLUTION: The scooter type motorcycle has the cam chain adjuster 66 provided on the side of the cylinder 32 of an engine unit 3 in the cross direction of the motorcycle for adjusting the tension of a cam chain 62. Thus, the cam adjuster 66 is prevented from being protruded upward and an upper tube 26 is prevented from receiving interference. No need therefore exists for raising the upper position of the upper tube 26 to avoid the interference and the upper edge of a front foot board 19 forming a foot-straddling space is kept lower. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating system for a scooter type motorcycle equipped with a 4-cycle engine.

[0002]

2. Description of the Related Art In the relationship between a frame and an engine in a scooter type motorcycle, in general, a main frame is curved largely downward from immediately after the steering head and is directly above the cylinder head in order to secure a leg straddling space in front of the seat. It extends through the back. The shape of the vehicle body cover in front of the seat is in line with the shape of the main frame, and the floor step, which is a footrest for the occupant, is provided at a lower position near the lower portion of the main frame. It is installed in the room to secure a space for straddling the legs. In this way, the main frame shape that can secure the space in front of and below the seat is secured to ensure the foot straddle characteristic of the scooter type motorcycle (see Japanese Patent Laid-Open No. 2000-303906, etc.).

When the valve operating mechanism of the engine is of the overhead camshaft type (OHC type), the rotational driving force of the crankshaft is normally transmitted to the intake valve / exhaust valve to the camshaft, and the intake valve is driven at a predetermined timing. -A cam chain is used as a transmission means to open and close the exhaust valve. Since the cam chain needs to accurately transmit the rotation of the crank shaft to the cam shaft, a cam chain adjuster is provided to adjust the cam chain to a constantly tensioned state by pressing the cam tune tensioner.

FIG. 6 is an explanatory view of a frame of a scooter type motorcycle and a cam chain adjuster of an engine mounted on the frame. As shown in FIG. 6, the main frame “a” falls from a head pipe (not shown), bends largely backward, and secures a foot straddling space “b” and extends backward. In addition, a down tube c that falls from the lower side of the head pipe and bends rearward at a position approaching the road surface with a predetermined distance and has a substantially L-shape and extends rearward
Is provided. The engine d has a portion a extending rearward of each of the main frame a and the down tube c.
The cylinder e is mounted so as to be located between the first and the first c1. In this engine d, cylinder e (cylinder shaft)
Is inclined forward and substantially horizontally, and the exhaust camshaft f and the intake camshaft g of the engine cylinder head are connected to a cam chain h between a crankshaft (not shown).
Is circulated and circulated to transmit the rotational driving force of the crankshaft. A cam chain tensioner i and a cam chain guide j that prevent the cam chain h from dancing and shaking are provided on the upper and lower sides of the circulation path of the cam chain h. The upper cam chain tensioner i pushes and adjusts the cam chain tensioner i toward the inside of the circulation path of the cam chain h by pushing out the plunger by the spring of the ratchet type cam chain adjuster k, etc. It is designed to maintain tension.

A conventional cam chain adjuster k is shown in FIG.
As shown in the side view of the vehicle body, the cam chain adjuster k projects from the side surface of the upper side of the cylinder, and the main frame a
Projecting upward from a portion a1 that extends rearward.

[0006]

In the conventional scooter type vehicle, in order to prevent the cam chain adjuster k from projecting upward from the main frame a as described above,
There is no choice but to raise the upper part of the main frame a. In addition, a front footboard is provided above the main frame around the footrest location as a cover for forming a footrest space. However, in the case where the cam chain adjuster k projects from the cylinder as described above, the footboard is elevated due to the influence. Will need to be located at. In other words, the lower edge of the straddle space becomes high. As a result, there is a problem that the straddle width b and the straddle height increase, such that the straddle space b is located at a high position, which deteriorates the straddle stride. Further, if the cam chain adjuster is protruding from the side surface of the cylinder head, it interferes with the frame when the engine is attached or detached, which causes a problem that maintainability deteriorates. Incidentally, Japanese Patent Laid-Open No. 2000-
As shown in No. 303906, in the case where the engine is mainly provided below the seat and behind the foot straddling space, even if the cam chain adjuster projects from the cylinder, interference can be avoided to some extent, but the engine straddles the foot. Since it is not under the space, there is a problem that the engine layout has a low degree of freedom, and the engine has to be arranged in a narrow space below the seat, resulting in poor maintainability.

The present invention has been made in view of the above-mentioned problems of the prior art, and in a four-cycle engine in which the cylinder is located below the main frame, the cam chain adjuster can be prevented from protruding upward from the cylinder. It is an object of the present invention to provide a valve operating system for a scooter type motorcycle that prevents the cam chain adjuster from interfering with the main frame and can reliably improve the foot straddle property and the maintainability.

[0008]

SUMMARY OF THE INVENTION The present invention is a scooter type motorcycle equipped with a four-cycle engine having a valve operating system for transmitting the rotation of a crankshaft to a camshaft for driving an intake valve and an exhaust valve via a cam chain. In the vehicle body frame, the vehicle body frame has a main frame that falls from a head pipe that indicates front steering and extends rearward through a continuous portion, and in the vehicle body frame, a cylinder is inclined forward and The engine is suspended so that the cylinder is positioned below the main frame continuous portion, and the vehicle body cover covers the main frame and the engine from above in front of the seat, and the front edge forms a passenger straddle space at the upper edge portion. A cam chain that has a footboard and adjusts the tension of the cam chain on the vehicle width direction side of the engine cylinder. A valve operating device of four-stroke scooter type motorcycle, characterized in that a Justa. In the present invention, the cam chain adjuster is inserted in the cam chain chamber of the engine cylinder, and is preferably provided on the cylinder or the cylinder head. Further, in the present invention, it is preferable that the engine location where the cam chain adjuster is disposed is provided at a position avoiding the lowermost portion of the upper edge portion of the front footboard.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 5 are explanatory views of an embodiment, FIG. 1 is an overall side view of a four-cycle scooter type motorcycle according to the embodiment, and FIG. 2 is a right side surface of a vehicle body frame suspending the engine unit and the engine unit. FIG. 3 is a left side view of the engine, FIG. 4 is a side view of the valve operating device around the cam chain adjuster of the engine unit, and FIG. 5 is an engine cylinder head cover removed to remove the cylinder head from the cylinder shaft. It is an explanatory view of the valve operating system seen from a direction and a distant place.

As shown in FIGS. 1 to 3, the embodiment has a valve operating device for transmitting the rotation of the crankshaft 9 to a camshaft for driving an intake valve and an exhaust valve via a cam chain.
The present invention relates to a scooter type motorcycle 1 equipped with a cycle engine. In this motorcycle 1, an engine unit 3 is suspended at a substantially central portion in the front-rear direction of a vehicle body frame 2 extending in the front-rear direction of the vehicle body. A front fork 5 having a front wheel 4 pivotally supported at a lower end and a handle 11 provided at an upper end is pivotally supported by a head pipe 21 at the front portion of the vehicle body so as to be steerable from side to side. Further, a rear wheel suspension device 8 that extends rearward and pivotally supports a rear wheel 7 is swingable in the vertical direction via a pivot shaft 6 that is provided behind the engine unit 3 along the vehicle width direction. Is supported by. In the engine unit 3, the front engine cylinder 32 is tilted substantially horizontally, and the crankshaft 9 is fixedly supported on the vehicle body frame 2 along the left and right in the vehicle width direction (floatingly supported via a rubber bush). ) Is suspended.

The vehicle body frame 2 includes a head upper tube 22 which stands down from a head pipe 21 which indicates front steering, and an upper tube 26 (main part) which extends rearward through a continuous portion 22a at a lower end of the head upper tube 22. (Corresponding to a frame), and is configured as shown below.

On the front side of the vehicle, as shown in FIGS. 1 and 2,
A head pipe 21 that supports a front fork 5 that rotatably supports a front wheel 4 so that the front fork 5 is rotatable left and right and is steerable, and a pair of left and right from the upper portion of the head pipe 21 diagonally rearward and downward, and in the middle. The head upper tube 22 is formed by being drooped and extending downward to a height approximately the same as the upper end of the front wheel by gradually increasing the angle from the bent portion to the downward direction and gently bending it into a substantially V shape. ,
It has a pair of left and right below the lower portion of the head pipe 21 and extends rearward and obliquely downward, and has a down tube 23 facing the head upper tube 22 and substantially parallel and shorter than the head upper tube 22.

Between the head upper tube 22 and the down tube 23, a side upper tube 24 that connects a substantially central portion near the bent portion of the head upper tube 22 and an end portion of the down tube 23 is formed in a front-rear direction hole. It is welded and fixed along. At the rear end (lower end) of the down tube 23, a pair of left and right lower down tubes 25 are provided so as to hang downward. The lower down tube 25 hangs downward at the rear of the front wheel 4, bends rearward from around the lower side of the cylinder 32 of the engine unit 3 which is inclined forward, and then inclines rearward and slightly upward. It is formed, extends in the vicinity of the crankcase 33 in a state of being bent and inclined further upward, and is welded and connected in the middle of the upper tube 26 described later.

At the center of the vehicle, an upper tube 26, which constitutes the main part of the vehicle body frame 2, extends from the lower rear of the head pipe 21 to above the rear wheel 8. The front end portion 22a of the upper tube 26 is welded and fixed near the front end portion of the lower down tube 25 (welding portion 25a), and a portion slightly rearward of the front end portion thereof is a continuous portion 22a of the lower end portion of the head upper tube 22. They are connected by welding, and extend from the rearward portion from the connecting portion 25a and the continuous portion 22a rearward with a slight downward inclination, and are bent upward from the front side of the rear wheel 8 and extend upward with a forward inclination. It is set up. The engine unit 3 includes suspension portions 27a, 27 at substantially the central portion and the rear end portion of the down tube 23 in the longitudinal direction and the substantially central portion of the lower down tube 25.
2, the engine case 36 of the engine unit 3 is suspended from the lower side of the lower down tube 25 as shown in FIG. As shown in FIG. 2, the upper tube 2 of the vehicle body frame 2
A lean hosement 28 is installed to diagonally connect the front of the suspension portions 27a, 27b, 27c of 6 and the lower down tube 25 to improve rigidity.

In the motorcycle 1, as shown in FIG. 1, the body pipe 10 covering the body frame 2 and the engine unit 3 and forming the outer shell of the vehicle body includes a head pipe 21 and a front fork 5. And handle 11
And the like, which covers the front steering around from the front and which shields the wind from the front of the occupant, and the front leg shield 12 having a substantially bow shape, and the rear which covers around the front steering from the rear and faces the occupants' feet directly. The leg shield 13 and the upper part have a substantially downward opening U-shape to cover the upper tube 26 and the engine cylinder 32, and the upper end forms the lower edge of the foot straddling space 15 in the front lower part of the seat 14 and to the left and right on both sides of the lower part. A front footboard 19 on which a floor step 18 which is a flat and flat footrest portion is formed, a frame cover front 50 that covers both left and right sides below the seat, and a frame that covers a frame behind the seat (a rear portion of the upper tube 26 and the like). A cover rear 51 is provided. The floor step 18 extends rearward to the lower side of the seat as a footrest portion for a passenger, which extends in the left-right direction of the vehicle body, below the frame cover front 50.

The front fork 5 covers the upper portion of the front wheel 4 which is rotatably supported at the lower end of the front fork 5.
Two are provided. A leg shield lower 53 is provided below the front and rear leg shields 12 and 13 to form a lower edge portion of the vehicle body cover 10 and to adjoin the road surface and to cover the engine unit 3 from both sides from below. The transparent windshield 1 is provided above the front leg shield 12 and in front of the handle 11.
2a is erected.

An intake duct opening 54 corresponding to the intake side opening 44a of the intake duct 44 installed in the transmission case 41 of the transmission 34 is provided on the vehicle right side surface portion of the frame cover front 50. Further, the seat 14 is a tandem seat in which the seat portions of the driver and the passenger are different in the front and rear, and the frame cover rear 51
The engine case 3 of the engine unit 3, which is the upper surface portion
6 to the rear wheel 4, and are installed so as to overlap the case 36 and the rear wheel 4 when viewed from above.
Further, the exhaust pipe 55 exiting the cylinder exhaust port of each cylinder of the engine unit 3 wraps around the lower side of the cylinder 32 and extends rearward, and the exhaust pipes 55 of the left and right cylinders join near the rear end pivot shaft 6 of the engine unit 3. The exhausts of the cylinders are collectively connected to a front end portion of a muffler 56 that is provided below the frame cover rear 51 and on the right side surface of the vehicle body and has a rearward rising inclination.

As shown in FIGS. 2 and 3, in the engine unit 3, the crankshaft 9 is oriented in the vehicle width direction, and a cylinder head 31 and a cylinder 32 for two cylinders are provided in front of the crankcase 33. A front horizontally installed engine equipped with a central axis of the cylinder that is substantially horizontal (substantially parallel to the road surface in a running state) and has a transmission 34 in the front-rear direction behind the crankcase 33. It is a unit engine with two cylinders and four cycles that are integrally installed in parallel with each other.

In the engine unit 3, an intake system is arranged above the cylinder center axis 38 in a side view of the vehicle, and a radiator and an exhaust system (the exhaust pipe 55 and the muffler 56 are arranged below the cylinder center axis. Is provided.

Cylinder 32 tilted forward almost horizontally
Above the cylinder head 31 of the intake manifold 31
a is formed. In the intake manifold 31a, an intake path communicating with an intake port (not shown), that is, an intake pipe, a throttle body, a carburetor inlet tube, and an air cleaner are arranged substantially linearly inclining upward toward the front. . The air cleaner includes a head upper tube 21 and a down tube 23.
And it is arrange | positioned in the space formed between the side upper tube 24 and it.

Although not shown, a V-belt type continuously variable transmission is accommodated inside the transmission case 41 of the engine case 36 as the transmission 34, and the reference numeral 42 is a drive side pulley to which the drive output of the crankshaft is input. Is a drive shaft, and 43 is a driven shaft on which a corresponding driven pulley is axially installed. An intake duct 44 for taking in outside air by a fan (not shown) of the driven shaft 43 accommodates the transmission 34. Is provided on the right side surface of the. Further, reference numeral 45 is an output shaft of the engine unit 3 coaxial with the pivot shaft 6 at the rear end of the engine case, and its output is input to the transmission unit 46 that transmits the driving force to the rear wheels 4.

Here, as shown in FIGS. 2 to 5, the cylinder head 31 is located inside the valve operating chamber 37 in the space covered by the cylinder head cover 35 and is located above the cylinder center axis 38 in a side view of the vehicle. An intake cam shaft (intake cam shaft) 16 for opening and closing the intake valve is provided, and an exhaust cam shaft (exhaust cam shaft) 17 for opening and closing the exhaust valve is provided below the cylinder center axis 38. The intake camshaft 16 and the exhaust camshaft 17 are covered with independent camshaft housings 57 and 58, respectively, and an intake cam sprocket 59 and an exhaust cam sprocket 60 are provided at the right end of the camshafts 16 and 17 in the vehicle body direction. Set up.
A cam chain chamber (cam chain passage) 61 is formed on the right side of the cylinder 32 toward the right side of the vehicle body. The cam chain chamber (cam chain passage) 61 communicates with the valve chamber 37 for accommodating the cam sprocket into the crank chamber. The intake cam sprocket 59 and the exhaust cam sprocket 60 face each other.

A cam chain 62 is wound around the intake cam sprocket 59 and the exhaust cam sprocket 60 of the engine cylinder head 31 through the cam chain chamber 61 and between the crank shaft 9 (not shown in FIGS. 5 and 6). And is circulated, and the rotational driving force of the crankshaft 9 is transmitted to the intake camshaft 16 and the exhaust camshaft 17. The cam chain tensioner 63 and the cam chain 62 for adjusting the tension of the cam chain 62 are provided on the upper side and the lower side (intake side and exhaust side) of the circulation path of the cam chain 62.
A cam chain guide 64 is provided to prevent the dance and blurring. Further, a cam chain guide 65 is provided between the cam sprockets 59 and 60 in the valve operating chamber 37 of the cylinder head 31 so as to be in sliding contact with and adjacent to the path of the cam chain 62 that wraps around.

In the cam chain tensioner 63 and each of the cam chain guides 64 to 65, shoes 63a to 65a made of a material having a low frictional resistance are provided on the circulation side of each cam chain 62 so as to be in sliding contact with the outer periphery of the cam chain 62. Has been. The cam chain tensioner 63 provided on the intake side, which is the upper side, uses the cam chain adjuster 66 to
The shoe 63a is pressed and adjusted toward the inside of the circulation path of the cam chain to keep the tension of the cam chain 62. The cam chain adjuster 66 can advance in only one direction (not retractable) by a ratchet mechanism (not shown) and is urged in the same direction by a spring to insert a rod body 66b into a guide body 66a fixed in the cam tune chamber 61. One end of the rod body 66b opposite to the traveling direction is rotatably connected to one end (camshaft side end) 63a of the cam chain tensioner 63. The other end of the cam chain tensioner 63 is pivotally supported at a predetermined position in the cam chain chamber 61, and when the tension of the cam chain 62 is loosened, the rod body 66b is advanced to restore the tension of the cam chain 62 to a predetermined degree. Has become.

As described above, according to the embodiment, since the cam chain adjuster 66 for adjusting the tension of the cam chain 62 is provided on the side of the cylinder head 31 of the engine unit 3 in the vehicle width direction, the cam chain adjuster 6 is provided.
6 does not project upward, and the upper tube 26 (an example of the main frame) is not interfered with. Therefore, since it is not necessary to raise the upper position of the upper tube 26 to avoid such interference, the position of the front footboard 19 forming the foot straddling space can be kept low. Therefore, in the scooter type motorcycle, the cam chain adjuster 66 can be prevented from projecting upward from the cylinder 32, so that the main frame is prevented from being positioned above and the foot straddling space 15 can be secured low to ensure the foot straddling property. Can be improved to the upper tube 26
Further, the cam chain adjuster 66 does not interfere with each other, so that an operator can easily inspect and maintainability can be improved.

Incidentally, the cam chain adjuster 66
Is inserted in the cam chain chamber 61 of the engine cylinder 32 and is provided in the cylinder 32 or the cylinder head 31, so that the cam chain adjuster 66 does not project from the side surface of the cylinder 31 or the cylinder head 31. Good maintainability when installing and removing the engine. Further, if the engine location where the Cam Cherna Juster 66 is disposed is provided at a position avoiding the lowermost part of the upper edge of the front footboard 19, the foot straddling space 15 can be secured and the foot straddling performance can be improved. .

[0027]

According to the present invention, in the vehicle body frame, the engine is suspended such that the cylinder is inclined forward and the cylinder is positioned below the main frame continuous portion, and the front of the vehicle body cover is suspended. A footboard covers the main frame and the engine from above in front of the seat, and forms an occupant foot straddling space at the upper edge,
Since the cam chain adjuster for adjusting the tension of the cam chain is provided on the side portion of the cylinder of the engine in the vehicle width direction, the cam chain adjuster does not project upward and the main frame is not interfered with. Therefore, since it is not necessary to raise the upper position of the main frame to avoid such interference, the position of the front footboard forming the straddle space can be lowered. Therefore,
In the scooter type motorcycle, the cam chain adjuster can be prevented from projecting upward from the cylinder, so that the main frame can be prevented from being located above, the leg straddle property can be reliably improved, and the maintainability can also be improved. The cam chain adjuster is inserted in the cam chain chamber of the engine cylinder, and if it is provided on the cylinder or cylinder head, the cam chain adjuster does not protrude from the side surface of the cylinder or cylinder head. There are no obtrusive protrusions, and maintenance is easy when the engine is attached or detached. Further, if the engine location where the cam chain adjuster is disposed is provided at a position avoiding the lowermost part of the upper edge of the front footboard, a foot straddling space can be secured and foot straddling performance can be improved.

[Brief description of drawings]

FIG. 1 is an overall side view of a 4-cycle scooter type motorcycle according to an embodiment of the present invention.

FIG. 2 is a right side view explanatory diagram of the engine unit and a vehicle body frame suspending the engine unit.

FIG. 3 is a left side view of the engine.

FIG. 4 is a side view explanatory diagram of a valve train around the cam chain adjuster of the engine unit.

FIG. 5 is an explanatory diagram of the valve operating system when the engine cylinder head cover is removed and the cylinder head is viewed from above in the cylinder axial direction (from the front because it is a forward tilt cylinder).

FIG. 6 is an explanatory view of a frame of a conventional scooter type motorcycle and a cam chain adjuster of an engine mounted therein.

[Explanation of symbols]

1 motorcycle 2 body frame 3 engine unit 10 Body cover 11 handle 12 front leg shield 13 Rear leg shield 14 seats 15 straddle space 16 intake camshaft 17 Exhaust cam shaft 18 floor steps 19 front footboard 21 head pipe 22 head upper tube 22a continuous section 23 Down Tube 25 lower down tube 26 Upper tube 31 cylinder head 32 cylinders 33 crankcase 34 transmission 35 cylinder head cover 36 engine case 37 Valve room 38 cylinder center axis 50 frame cover front 51 frame cover rear 52 front fender 53 Leg Shield Lower 55 exhaust pipe 56 muffler 57, 58 Camshaft cover 59 intake cam sprocket 60 exhaust cam sprocket 61 Cam chain room 62 cam chain 63 Cam chain tensioner on intake side 64 Exhaust side cam chain guide 65 Cam chain guide in valve train 66 Cam Chain Adjuster

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02B 61/02 F02B 61/02 D 67/06 67/06 A F16H 7/08 F16H 7/08 B F term (Reference) 3G016 AA02 AA06 AA08 AA12 BA23 BA24 CA42 DA21 FA27 FA39 GA00 3G024 AA48 DA03 DA08 DA10 DA18 EA04 FA14 GA26 3J049 AA08 AB03 BB02 BB10 BB13 BB23 BC03 CA10

Claims (3)

[Claims] 1. A scooter type motorcycle equipped with a 4-cycle engine having a valve operating device for transmitting the rotation of a crankshaft to a camshaft for driving an intake valve / exhaust valve via a cam chain, wherein a vehicle body frame has a front body. A main frame is provided that extends downward from a head pipe that indicates steering and extends rearward through a continuous portion. The body frame has a cylinder inclined forward and the cylinder includes a main frame continuous portion. The engine is suspended so as to be positioned below the vehicle body cover, and the vehicle body cover has a front footboard that covers the main frame and the engine from above in front of the seat, and forms an occupant foot straddling space at the upper edge portion, A cam chain adjuster that adjusts the tension of the cam chain is provided on the side of the engine cylinder in the vehicle width direction. Scooter type motorcycle valve operating system according to claim. 2. The scooter type motorcycle according to claim 1, wherein the cam chain adjuster is inserted in a cam chain chamber of an engine cylinder, and is provided in a cylinder or a cylinder head. Valve device. 3. The scooter type motorcycle according to claim 1, wherein the engine location where the cam chain adjuster is disposed is provided at a position avoiding the lowermost portion of the upper edge portion of the front footboard. Valve drive.