JP3576301B2 - Air-cooled engine cylinder head anti-vibration structure - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an air-cooled engine, and more particularly to a cylinder head vibration isolating structure that prevents fin squeal due to vibration of cooling fins.
[0002]
[Prior art]
Generally, an air-cooled engine has a structure in which cooling fins extending in the vehicle traveling direction are integrally formed on outer wall surfaces of a cylinder head and a cylinder block, and heat is radiated through the cooling fins by traveling wind. In such an air-cooled engine, conventionally, in order to prevent fin squeal due to vibration of the cooling fin, a plate-shaped head cover is bolted and fixed with an elastic sheet interposed on the top surface of the cooling fin of the cylinder head. (See, for example, Japanese Utility Model Laid-Open No. 53-207). Further, there is also a configuration in which an elastic member is pushed between the cooling fins, or a hole is formed in each cooling fin, and a vibration of the cooling fin is prevented by driving an elastic member into the hole. .
[0003]
[Problems to be solved by the invention]
However, in the above-described vibration damping structure of the related art, there is a problem that an end face of the elastic sheet and the head cover disposed on the top surface of the cooling fin is exposed to the side and the appearance is deteriorated. Further, the structure in which the elastic member is pushed between the cooling fins has a problem that the number of parts increases.
[0004]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an air-cooled engine capable of preventing the side exposure of an end surface of an elastic sheet or the like to improve the appearance and reducing the number of parts. It is intended to provide a cylinder head vibration isolating structure.
[0005]
[Means for Solving the Problems]
A first aspect of the present invention relates to a cylinder head vibration isolating structure of an air-cooled engine, wherein fin squeal is prevented by preventing vibration of a heat-dissipating cooling fin formed on the upper surface of the cylinder head so as to extend in the vehicle traveling direction. The height of the top surface of the left and right outer cooling fins located on the outside in the thickness direction of the cooling fins is higher than the height of the top surface of the inner cooling fin located on the inside, and the elastic sheet is placed on the top surface of the inner cooling fin It is characterized in that a plate-shaped head cover is arranged and fixed with interposition, and the outer cooling fin and the inner cooling fin adjacent to the fin are integrally connected by a rib.
[0006]
According to a second aspect of the present invention, in the first aspect, a cutout portion is formed in the inner cooling fin adjacent to the outer cooling fin.
[0007]
[Means for Solving the Problems]
A first aspect of the present invention relates to a cylinder head vibration isolating structure of an air-cooled engine, wherein fin squeal is prevented by preventing vibration of a heat-dissipating cooling fin formed on the upper surface of the cylinder head so as to extend in the vehicle traveling direction. The height of the top surface of the left and right outer cooling fins located outside the thickness direction of the cooling fins is made higher than the height of the top surface of the inner cooling fin located inside, and the elastic sheet is placed on the top surface of the inner cooling fin. A plate-shaped head cover is disposed and fixed with interposition, and the outer cooling fin and the inner cooling fin adjacent to the fin are integrally connected by a plurality of ribs, The height of the top surface of the rib was substantially the same as the height of the top surface of the inner cooling fin, and the elastic sheet was brought into contact with the top surface of the rib. It is characterized by:
[0008]
In the figure, reference numeral 1 denotes a motorcycle. A body frame 2 of the motorcycle 1 is connected to a head pipe 3 at a front end of one main frame 4 which extends obliquely downward and rearward of the vehicle body. An upwardly extending U-shaped gusset 7 (reinforcement) is connected to an upwardly extending rail bracket 6 having a U-shaped cross section so as to surround the connection portion, that is, the upper portion of the rail bracket 6 and the rear end of the main frame 4. Plate and a pair of left and right seat rails 5 extending diagonally upward and rearward of the vehicle body are connected to upper ends of the gussets 7 and the rail brackets 6.
[0009]
A back stay 8 is provided between each of the seat rails 5 and the rail bracket 6, and a seat tube 9 is provided upright on the upper surface of the gusset 7. A support bracket 10 is connected to a substantially central lower side of the main frame 4, and a suspension bracket 11 extending downward is connected to a rear end of the main frame 4, and the engine 12 is supported by the two brackets 10, 11.
[0010]
The seat tube 9 pivotally supports a front end of a seat 13 integrally formed with a front seat 13a and a rear seat 13b. Below the seat 13, an oil tank 14, a battery 15, and a fuel tank 16 are provided, respectively. Are arranged.
[0011]
A front fork 20 is pivotally supported by the head pipe 3. A front wheel 21 is mounted on a lower end of the front fork 20, and a steering handle 22 is mounted on an upper end. A rear arm 24 is pivotally supported on the suspension bracket 11 via a pivot shaft 23 so as to be vertically swingable. A rear wheel 25 is mounted on the rear end of the rear arm 24. A rear cushion 27 is provided between the rear arm 24 and the rail bracket 6.
[0012]
A cowling 31 to which a headlight 30 is attached is provided at a front portion of the head pipe 3, and a steering handle 22 is provided at an upper portion. An under cover 33 extending downward and surrounding the engine 12 is provided on the left and right portions of the main frame 4, and a side cover 34 is provided on a lower surface of the seat 13. A tail is provided on a rear end of the side cover 34. Light 35 is mounted.
[0013]
As shown in FIG. 3, the engine 12 is an air-cooled two-stroke engine mounted on the body frame 2 with the axis (cylinder axis) of the cylinder bore 37d inclined forward by about 35 degrees. A cylinder body 37 is laminated on the upper surface of the crankcase 36, and a cylinder head 38 is laminated on the upper surface of the cylinder body 37 and fastened with a head bolt. A piston 39 is inserted into a cylinder bore (cylinder) 37d of the cylinder body 37. The piston 39 is slidably inserted, and the piston 39 is connected to a crankpin 42 of a crankshaft 41 by a connecting rod 40. A combustion recess 38a is formed in the lower surface of the cylinder head 38, and the electrode of the ignition plug 42 is exposed in the recess 38a.
[0014]
The inside of the crankcase 36 is divided by a partition wall 36c into a crank chamber 36a that houses the crankshaft 41 and a transmission chamber 36b that houses the transmission mechanism 43. The transmission mechanism 43 transmits the rotation of the crankshaft 41 to the rear wheel 25 via a centrifugal auto clutch (not shown) mounted on the right end thereof, a main shaft 43a, a drive shaft 43b, and a sprocket and a chain not shown. It is designed to communicate. Incidentally, reference numeral 47 in FIG. 1 denotes a chain cover.
[0015]
A balancer shaft 45 is disposed below and parallel to the crankshaft 41. A cell motor 46 has a drive shaft 46a directed toward the left side of the vehicle body at a front portion of a front wall 36d of the crankcase 36. It is arranged parallel to the crankshaft 41. Although not shown, a centrifugal auto clutch is mounted on the right end side of the crankshaft 41.
[0016]
On the outer peripheral wall of the cylinder body 37, a plurality of cooling fins 50 for heat radiation standing upright in a direction perpendicular to the cylinder axis are integrally formed at intervals in the cylinder axis direction. Are integrally connected by the rib 50a. A plurality of scavenging ports 51 are formed in the cylinder wall of the cylinder body 37 to communicate the crank chamber 36a and the inside of the cylinder bore 37d. Further, in the lower mating surface 37b of the cylinder body 37 connected to the crankcase 36, a lightening concave portion 37a for reducing the weight is formed as shown in FIGS.
[0017]
Next, an anti-vibration structure of the cylinder head 38 in the present embodiment will be described.
As shown in FIGS. 4 to 6, a number of cooling fins that stand in the cylinder axis direction and extend in the vehicle traveling direction are integrally formed on the upper wall of the cylinder head 38 at intervals in the vehicle width direction. ing. Of the cooling fins, the top surface height of the outermost fins 52a, 52a located on the left and right outermost sides in the thickness direction (vehicle width direction) is a portion excluding the front end 52b 'of each inner fin 52b located on the inside. Is higher than the top height. The top surface of the front end 52b 'of each inner fin 52b is formed at the same height as the outer fin 52a. That is, each of the inner fins 52b is formed in a stepped shape. On the top surface of the stepped portion of each inner fin 52b, a head cover 54 made of a metal plate is disposed via an elastic sheet 53 made of a rubber plate, and the upper surface of the head cover 54 and the outer fins 52a and the The front end 52b 'is flush with the top surface. The head cover 54 is fixedly fastened by screwing bolts 57 to bosses 38d integrally formed at four corners of the cylinder head 38. A hole 53a is formed in a portion of the elastic sheet 53 corresponding to the stud bolt hole 38b and the spark plug hole 38c.
[0018]
Both ends in the longitudinal direction of the left and right outer fins 52a and the inner fin 52b adjacent to the fins 52a, and a central portion are integrally connected by a rib 60. A cutout 61 is formed in a portion of the adjacent inner fin 52b where the rib 60 is connected. The notch 61 is an opening that opens the space a formed by the fins 52a and 52b and the rib 60 outward at a low place in the vehicle-mounted state. Discharge passage is formed.
[0019]
Of the inner fins 52b, each of the fins 52b located at the center in the vehicle width direction is formed with a relief recess 62 having a semicircular shape in a plan view formed by cutting out a rear edge thereof. The lower edge is located. By forming the escape recess 62, the cylinder head 38 can be attached and detached while the engine is mounted on the vehicle body without changing the size and shape of the main frame 4 and the inclination angle of the engine 12. That is, in order to make the cylinder head detachable while the engine is mounted on the vehicle, it is conceivable to increase the forward tilt angle of the engine or change the frame position upward, but in this case interference with the front fender, There is a problem that the degree of freedom of the frame shape is reduced. Further, since the concave portion 62 is on the opposite side of an exhaust port to be described later, there is almost no effect on cooling performance, and since only a part of the inner fin 52b is cut out, the contact area of the elastic sheet 53 is extremely reduced. No impact on the anti-vibration measures can be avoided.
[0020]
An exhaust port 65 communicating with the cylinder bore 37d is formed obliquely downward on the front wall of the cylinder body 37. Further, an annular convex flange portion 66 is formed on the periphery of the external connection opening of the exhaust port 65, and the convex flange portion 66 is formed so as to be recessed in the direction of arrow a in FIG. 7 so as to approach the center side of the cylinder bore. ing. This reduces the volume around the exhaust port 65 and suppresses the amount of heat stored by the exhaust gas. In addition, since the convex flange portion 66 is recessed, the bending radius of the exhaust pipe 67 can be increased, and the bending of the exhaust pipe 67 can be easily performed. And the problem of interference with the front wheels is less likely to occur. On the other hand, since the convex flange portion 66 is recessed, the lower half portion 66b of the flange portion 66 is separated from the bolt boss portion 37c for fixing the cylinder body 37 to the crankcase 36 as shown in FIG. Since it is located on the center side of the cylinder bore, the shape of the casting mold is restricted as described later.
[0021]
The flange portion 67b of the exhaust pipe 67 is bolted and fixed to the convex flange portion 66 with a gasket (not shown) interposed therebetween. The exhaust pipe 67 extends downward from the cylinder body 37 and then to the right side of the vehicle body and extends rearward therefrom. A muffler 67a is connected to a rear end of the exhaust pipe 67.
[0022]
Next, the mold of the cylinder body 37 in the present embodiment will be described. The cylinder body 37 is manufactured by using the mold 70 shown in FIGS. That is, the mold 70 includes a pair of left and right mother dies 71 and 72 for forming the main part of the cylinder body 37, and the exhaust port 65 and the convex flange in cooperation with the two mother dies 71 and 72. An exhaust core 73 forming an upper half 66a located on the cylinder head side of the portion 66, a lightening concave portion 37a of a lower mating surface 37b of the cylinder body 37, and a crankcase side of the convex flange portion 66. And a lightening die 74 forming a lower half 66b.
[0023]
The exhaust core 73 includes a generally conical port portion 73a forming the exhaust port 65, and a cylindrical portion 73b forming the peripheral edge of the port opening and the inner peripheral surface of the convex flange portion 66. The upper half part 66a of the convex flange 66 is formed by the arc-shaped notch concave parts 71a, 72a formed on the left and right mother dies 71, 72. A support portion 73c for positioning and supporting the core 73 at the time of casting is formed to project from the tip end surface of the port portion 73a.
[0024]
The lightening die 74 is formed by integrally forming a lower mating surface 37b of the cylinder body 37, a base portion 74a forming a part of the boss portion 37c, and a support portion 74c for supporting the cylindrical portion 73b of the core 73. A pair of convex portions 74b forming the lightening concave portion 37a are protruded on the base portion 74a, and the convex flange portion 66 is formed on the periphery of the support portion 74c by the cylindrical portion 73b. A lower half mold portion 74d forming the lower half portion 66b is recessed.
[0025]
After casting the molten metal into the mold 70, the cylinder body 37 divides the left and right mother dies 71, 72 into right and left molds, and cuts the exhaust core 73 rearward in the port axial direction. Is die-cut downward in the axial direction of the cylinder bore.
[0026]
An intake opening 36e communicating with the crank chamber 36a is formed in a rear upper wall of the crankcase 36, and a reed valve 75 is inserted into the opening 36e. The reed valve 75 is a single-opening type having only a valve plate that opens upward. When the piston 39 rises, the crank chamber 36a automatically opens when a negative pressure is applied and air is introduced. To prevent air from blowing back. A carburetor 76 is connected to the upstream side of the reed valve 75 of the intake opening 36d, and an air cleaner device 68 is connected to an upstream side of the carburetor 76.
[0027]
Next, the air cleaner device 68 will be described.
As shown in FIGS. 12 and 13, the air cleaner device 68 forms an air introduction chamber A with the gusset 7 surrounding the connection portion of the above-mentioned main frame 4 and the rail bracket 6 and the gusset 7. An air cleaner case 80 made of resin is disposed on the left side of the case. At the time of welding between the main frame 4 and the gusset 7 at the bottom of the air introduction chamber A, a gap is provided by not intentionally welding a part to drain the water. If rainwater or the like invades into the water, it falls down and drains from the drainage part.
[0028]
The air cleaner case 80 is of a left- and right-split type consisting of a case body 81 and a case cover 82. The case body 81 is provided with flanges 81a and 81b projecting from the outer wall of the body body 2 so as to cover the body frame 2. Bolts.
[0029]
An element 83 for separating the case main body 81 and the case cover 82 is provided at a joint portion between the case main body 81 and the case cover 82. The element 83 is formed by an engaging projection 84 integrally formed on the periphery of the case main body 81 and the case cover 82. It is clamped and fixed. The case cover 82 is detachably attached to the case body 81 by engaging a boss 82a integrally formed with the case cover 82 so as to be coaxial with the boss 81c of the case body 81 and screwing a bolt 85. ing. Thus, the element 83 can be replaced simply by removing the case cover 82.
[0030]
A cylindrical intake duct 86 extending in the vehicle width direction is integrally formed in the case main body 81, and an upstream intake port 86 a of the intake duct 86 protrudes outward from the case main body 81. A downstream air inlet 86b of the air intake duct 86 penetrates through the element 83 and opens into the case cover 82. A discharge port 81d is formed in a front wall of the case body 81, and an upstream end of the vaporizer 76 is connected to the discharge port 81d via an intake pipe 87.
[0031]
The gusset 7 has an intake port 7a at the left rear and an air intake port 7b at the front right. The upstream intake port 86a of the intake duct 86 passes through the intake port 7a. It is open in the air introduction chamber A. A substantially bowl-shaped suction cover 26 surrounding the opening 7b is fastened and fixed to the gusset 7 by bolts inserted into the bosses 26f and 26g, thereby preventing rainwater or the like from entering the opening 7b. I have. Suction ports 26a to 26d are formed in the suction cover 26, so that the area of the suction port is sufficiently secured and suction resistance is reduced while preventing the rainwater from entering. A cover mounting boss 26e is formed at the front end of the suction cover 26 in the vehicle width direction, and a side cover 34 is fixed to the boss 26e by bolts.
[0032]
In this manner, the air sucked from the air opening 7b through the suction ports 26a to 26d of the suction cover 26 is introduced into the case cover 82 from the air introduction chamber A through the air intake duct 86, and from there the element After being filtered at 83, it enters the case body 81 and is supplied to the vaporizer 76 from the discharge port 81 d (see the mark → in FIG. 12).
[0033]
Next, a neutral kick starting device according to the present embodiment will be described with reference to FIGS.
In the neutral kick starter, when a kick arm 91 disposed on the right side of the engine 12 is depressed, the kick shaft 90 rotates, and with the rotation, the ratchet 92 moves rightward in the axial direction and moves to the kick gear 93. The crankshaft 41 is configured to engage with the crankshaft 41 via the first speed gear 94 by the rotation of the kick gear 93. The first speed gear 94 is rotatable on the drive shaft 43b in a state where a gear dog (not shown) is not engaged.
[0034]
The crankcase 36 is divided into left and right cases (first and second cases) 95a and 95b, and a case cover 95c is detachably mounted on the right case 95b. The left end of the kick shaft 90 is supported by a left case 95a, the center is supported by a right case 95b, and the right end is supported by a case cover 95c. A stopper 96 is fixed to the inside of the left case 95a of the kick shaft 90 by caulking. The stopper 96 abuts on a case-side stopper (not shown) to regulate the return position (position before rotation) before the kick shaft 90 is depressed. The kick gear 93 is mounted on the inside of the right case 95b of the kick shaft 90 so as to be relatively rotatable, and the kick gear 93 is held by the circlip 97a and the stopper plate 97b so as not to move in the axial direction.
[0035]
A return spring 98 is mounted between the right case 95b and the case cover 95c of the kick shaft 90 to constantly bias the kick shaft 90 in the anti-stepping direction, that is, toward the return position. One end 98a of the spring 98 is locked to the right case 95b, and the other end 98b is locked to the kick shaft 90. A collar 99 is provided between the right case 95b of the kick shaft 90 and the case cover 95c.
[0036]
The ratchet 92 disposed between the stopper 96 of the kick shaft 90 and the kick gear 93 meshes with a torsion spline 90a formed on the kick shaft 90. The ratchet 92 rotates to a predetermined torque. A spring 100 for holding the spring 100 is mounted, and one end of the spring 100 is locked to the ratchet 92 and the other end is locked to the left case 95a.
[0037]
The stopper 96, the ratchet 92, and the kick gear 93 may be arranged symmetrically with respect to FIG. 14, that is, the stopper 96, the ratchet 92, and the kick gear 93 may be arranged in order from right to left in the drawing.
[0038]
Here, the operation of the ratchet 92 will be described. When a rotational force is applied to the ratchet 92 along with the rotation of the kick shaft 90, the ratchet 92 does not rotate because it is held by the spring 100, and therefore the torsional spline 90a reduces the axial driving force of the kick shaft 90. It moves to the receiving kick gear 93 side. When the dog 92a of the ratchet 92 is engaged with the dog 93b of the kick gear 93, the rotation of the kick shaft 90 is transmitted to the kick gear 93 via the ratchet 92, and the kick gear 93 rotates the crankshaft 41 via the first speed gear 94. Will be done.
[0039]
Next, the operation and effect of the present embodiment will be described.
According to the cylinder head anti-vibration structure of the present embodiment, the height of the top surface of the left and right outer fins 52a is made higher than the height of the top surface of the inner fin 52b, and the elastic sheet 53 is interposed on the top surface of the inner fin 52b. Since the head cover 54 is fastened and fixed together by the bolts 57, fin squeak due to fin vibration can be prevented. In this case, the end surfaces of the elastic sheet 53 and the head cover 54 are covered with the outer fins 52a and are not visible from the side, so that the appearance from the side can be improved. Also, the number of components can be reduced and the cost can be reduced as compared with the conventional case where an elastic member is pushed between fins or the like.
[0040]
Since the left and right outer fins 52a and the adjacent inner fins 52b are integrally connected by the rib 60, the rigidity of the left and right outer fins 52a can be increased, and the fins caused by the vibration of the outer fins 52a can be provided. Squeak can be prevented. In addition, since the elastic sheet 53 and the head cover 54 are in contact with the outer fins 52a, the vibration of the outer fins 52a can be prevented from this point as well.
[0041]
Furthermore, since the upper surfaces of the outer fins 52a and the adjacent inner fins 52b are covered with the head cover 54 and the like, muddy water and the like can be prevented from entering the space a surrounded by the fins 52a, 52b and the ribs 60. Further, since the notch 61 is formed in the inner fin 52b, even if muddy water or the like enters the space a, the muddy water or the like that has entered is discharged outward from the notch 61. Water, mud and the like due to the formation of 60 can be prevented.
[0042]
Since the notch 61 is formed not on the outer fin 52a but on the inner fin 52b, the notch is not seen in a side view, and the appearance of the notch can be prevented from being deteriorated by providing the notch. Further, since the muddy water flows out to the front side of the vehicle, the muddy water does not become dirty when viewed from the side, and the appearance can be prevented from being deteriorated from this point as well.
[0043]
Here, as shown by a two-dot chain line in FIG. 5, for example, a leg 53a may be integrally formed on the elastic sheet 53 and the leg 53a may be pushed between the outer fin 52a and the inner fin 52b. . In this case, the vibration of the outer fins 52a can be further suppressed without increasing the number of parts, and the number of ribs 60 can be reduced or omitted.
[0044]
According to the cylinder body mold 70 of the present embodiment, the upper half 66a of the convex flange 66 is formed by the left and right mother dies 71, 72 and the exhaust core 73, and the lower half 66b is formed. Since the exhaust core 73 is formed by the lower half mold part 74d formed in the hollow mold 74, the exhaust core 73 is formed by the exhaust port port 73a and the inner peripheral surface of the convex flange 66. The core structure can be simplified, and the core structure can be simplified and the cost can be reduced as compared with the conventional case where separate cores are formed and then joined.
[0045]
Further, the hollow portion 37a and the lower half portion 66b of the convex flange portion 66 can be simultaneously formed only by the hollow portion 74, so that a separate mold member is not required and the cost can be reduced accordingly.
[0046]
According to the air cleaner device 68 of the present embodiment, the air inlet chamber A is constituted by the connection portion of the main frame 4 and the rail bracket 6 and the gusset 7 surrounding the portion, and the air cleaner 80 is provided at the air inlet 7a of the gusset 7. Since the intake duct 86 is inserted and opened into the air introduction chamber A, it is possible to reliably prevent water from entering. Further, since the intake port 7a is located higher than the bottom of the air introduction chamber A, the water that has entered the air introduction chamber A does not enter the intake duct section 8b. The main frame 4, which is consciously provided at the lowest position, is discharged to the outside through a non-welding point (drainage) between the set 7 and the main frame 4 to prevent intrusion of water from entering the air. it can. As a result, it is possible to reliably prevent rainwater or the like from being sucked in without requiring a special water-intrusion prevention plate.
[0047]
Further, since the intake duct 86 is formed integrally with the case body 81, the cost can be reduced as compared with a case where a separate duct is provided. Further, since the volume of the air introduction chamber A is larger than that of other body parts, the intake amount does not decrease, and the interior of the gusset 7 having higher rigidity is set as the air introduction chamber A. It can be prevented from becoming a source. Further, since the intake duct 86 is provided and the inside of the air cleaner is inverted, and both the upstream intake port 86a and the discharge port 81d are formed on the case body 81 side, a communication portion as an intake passage is unnecessary on the case cover 82 side. Since the structure is easy to attach and detach, maintenance such as cleaning and replacement of the element is easy. Further, since the element 83 is sandwiched between the case body 81 and the case cover 82 and the case cover 82 is detachable, the element 83 can be replaced simply by removing the case cover 82, which also facilitates maintenance. Can be done.
[0048]
According to the kick starting device of the present embodiment, when the kick shaft 90 is bridged between the left and right cases 95a and 95b to support the kick shaft 90, the stopper 96 is fixed to the left case 95a side of the kick shaft 90 and the ratchet 92 is fixed. Since the kick gear 93 is mounted, the assembling work can be easily performed. That is, when assembling the kick shaft 90 to the crankcase 36, the stopper 96, the ratchet 92, and the kick gear 93 are attached to the kick shaft 90 in advance, and the left end is assembled to a shaft support hole of the left case 95a. After the case 95a and the right case 95b are joined, the kick shaft 90 is turned to the pre-rotation position so that the stopper 96 comes into contact with the case-side stopper at a portion of the kick shaft 90 protruding outward from the right case 95b. The return spring 98 is mounted in the moving state, and the collar 99 is mounted. Then, the case cover 95c may be attached, and finally, the kick arm 91 may be attached. Therefore, it is not necessary to perform the mounting work while aligning the stopper and the ratchet as in the related art, and the workability can be improved. A slit is formed in the collar 99, and the collar 99 can be mounted after the spring 98 is mounted by locating the end of the return spring 98 in the slit.
[0049]
Further, a spring and a guide for moving the conventional ratchet in the axial direction can be dispensed with, and only one circlip for holding the kick gear immovably is required, so that the number of parts and the number of working steps can be reduced, and the cost can be reduced. .
[0050]
In the above embodiment, the case where the kick arm is arranged on the right side of the engine has been described, but the kick arm may be arranged on the left side. In this case, the arrangement positions of the respective parts are symmetric with respect to FIG.
[0051]
【The invention's effect】
According to the first aspect of the present invention, the height of the top surface of the left and right outer cooling fins located on the outside in the thickness direction of the cooling fin is higher than the height of the top surface of the inner cooling fin located on the inside, and the inner cooling fin is provided. The plate-shaped head cover is arranged and fixed with an elastic sheet interposed on the top surface, so that the vibration of the inner cooling fins can be suppressed to prevent fin squeak, and the end surfaces of the elastic sheet and the head cover are exposed to the side. However, there is an effect that the appearance can be improved, and the number of parts can be reduced and the cost can be reduced as compared with a case where the elastic member is pushed between the fins. Since the left and right outer fins and the adjacent inner fins are integrally connected by a rib, the rigidity of the outer fins can be increased, and the outer fins can be prevented from fin squeal due to vibration without being covered with an elastic sheet or a head cover. There is an effect that can be done.
[0052]
According to the second aspect of the present invention, since the notch is formed in the adjacent inner fin, muddy water or the like that has entered the space surrounded by both the fins and the rib can be discharged from the notch, thereby forming the rib. This has the effect of preventing water, mud and the like from being clogged.
[0053]
In addition, since the notch is formed not on the outer fin but on the inner fin, the appearance seen from the side of the outer fin can be secured, and water and mud flowing out of the notch flow out to the front side of the head. This has the effect of ensuring the appearance in side view.
[Brief description of the drawings]
FIG. 1 is a left side view of a motorcycle for explaining a cylinder head vibration isolating structure of an air-cooled engine according to one embodiment of the first and second aspects of the invention.
FIG. 2 is a left side view of a body frame of the motorcycle.
FIG. 3 is a left side sectional view of the air-cooled engine.
FIG. 4 is a plan view of a cylinder head of the engine.
5 is a sectional front view of the cylinder head (a sectional view taken along line VV in FIG. 4).
FIG. 6 is a left side sectional view of the cylinder head.
FIG. 7 is a left side sectional view of a cylinder body of the engine.
FIG. 8 is a bottom view of the cylinder body.
FIG. 9 is a right side view showing a mold of the cylinder body.
FIG. 10 is a front view showing the mold.
FIG. 11 is an exploded perspective view of the mold.
FIG. 12 is a sectional plan view of the air cleaner device of the engine.
FIG. 13 is a left side view of the air cleaner device with a case cover removed.
FIG. 14 is a sectional plan view of the kick starter for the engine.
FIG. 15 is a right side view of the kick starting device with a case cover removed.
FIG. 16 is a view showing a suction cover of the air cleaner device.
[Explanation of symbols]
12 Air-cooled engine
38 cylinder head
52 Cooling fin
52a Outer fin
52b inner fin
53 elastic sheet
54 Head Cover
60 ribs
61 Notch

Claims (2)

In the cylinder head vibration isolating structure of the air-cooled engine, which prevents the fin from squeezing by preventing the vibration of the cooling fin for heat dissipation formed on the upper surface of the cylinder head so as to extend in the vehicle traveling direction, in the thickness direction of the cooling fin A plate-shaped head cover in which the top surfaces of the outer left and right outer cooling fins are higher than the inner surface of the inner cooling fins and an elastic sheet is interposed on the top surface of the inner cooling fins The outer cooling fin and the inner cooling fin adjacent to the fin are integrally connected by a plurality of ribs , and the top surface height of the rib is substantially the same as the top surface height of the inner cooling fin. A vibration-absorbing structure for a cylinder head of an air-cooled engine , wherein the elastic sheet is in contact with a top surface of the rib . 2. The cylinder head vibration damping structure for an air-cooled engine according to claim 1, wherein a cutout portion is formed in the inner cooling fin adjacent to the outer cooling fin.

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