JP5911015B2 - Motorcycle - Google Patents

Description

  The present invention relates to an improvement of a motorcycle provided with a mass damper.

  The vibration generated in the motorcycle is roughly classified into vibration caused by engine rotation and vibration received from the road surface during traveling. As a countermeasure against vibration caused by engine rotation, for example, there is one in which a vibration isolating member is interposed between the engine and the vehicle body frame. On the other hand, as a countermeasure against vibration received from a road surface or the like, for example, there is one in which a mass damper is disposed on a swing arm (see, for example, Patent Document 1 (FIG. 2)).

  As shown in FIG. 2 of Patent Document 1, the left and right sides of the rear end of the swing arm (22) that supports the rear wheel (24) (the numbers in parentheses indicate the reference numerals described in Patent Document 1. The same shall apply hereinafter). Mass dampers (30, 30) are attached. If vibration occurs when the vehicle turns, this vibration can be reduced by the left and right mass dampers (30, 30).

However, the arrangement space for other components is reduced by the amount of mass dampers (30, 30) provided. However, in a motorcycle in which the arrangement space for parts is large, it is not preferable to reduce the arrangement space for parts.
Therefore, it is desirable to secure a parts placement space equivalent to a motorcycle without a mass damper even if the motorcycle has a large restriction on the parts placement space.

JP 2011-183981 A

  It is an object of the present invention to provide a technology that can secure a component arrangement space equivalent to a motorcycle that does not include a mass damper even if the motorcycle has a large restriction on the component arrangement space.

The invention according to claim 1 is a vehicle body frame, a front wheel provided at a front portion of the vehicle body frame, a rear wheel provided at a rear portion of the vehicle body frame, an engine provided between the front wheel and the rear wheel, In a motorcycle provided with a head pipe provided at the front end, a steering shaft provided rotatably on the head pipe, and a pair of left and right front forks provided integrally with the steering shaft and supporting the front wheel The head pipe includes a weight and an elastic member that supports the weight, and a cylindrical mass damper that absorbs vibration by moving the weight is disposed . It is characterized by being suspended on the edge.

The invention according to claim 2 is characterized in that a fluid passage is formed in the weight along the moving direction of the weight, and a rubber orifice member is attached to the mouth of the fluid passage opened at both ends of the weight. To do.

The invention according to claim 3 is characterized in that the elastic member is a coil spring, and at least a part of the weight is disposed inside the coil spring.

In the invention according to claim 4 , the mass damper is inserted into the steering shaft and has an outer cylinder that slidably supports the weight inside the mass damper, and the outer cylinder is an inner peripheral surface of the steering shaft. And an outer peripheral surface that radially supports the outer cylinder, and an abutting surface that is increased in diameter outwardly from the outer peripheral surface and contacts the upper opening and supports the outer cylinder in the axial direction.

The invention according to claim 5 is characterized in that the mass damper is set to absorb vibrations of 15 Hz to 25 Hz.

The invention according to claim 6 is characterized in that an O-ring is attached to a lower portion of the outer cylinder between the outer cylinder and the steering shaft.

In the invention according to claim 7 , the upper end of the outer cylinder is closed with a cap, and this cap has a cylindrical fluid reservoir having a communication hole communicating with the outer cylinder, and fills the mass damper with the fluid. A pressure adjusting mechanism that maintains the pressure of the fluid in the mass damper at a predetermined pressure by a fluid reservoir, a piston that can slide in the fluid reservoir, and a spring that presses the piston toward the communication hole. It is characterized by comprising.

  In the invention according to claim 1, a cylindrical mass damper is arranged in the head pipe. If the mass damper is arranged outside the head pipe, a large space is taken outside the front fork. Then, there is a possibility that the layout of other parts may be hindered.

  In this regard, in the present invention, since the mass damper is arranged in the head pipe, it is not necessary to arrange the mass damper outside the head pipe. Since the mass damper is arranged in the head pipe, there is no concern that the layout of other parts will be hindered, and it is not necessary to secure a new mass damper arrangement space. As a result, even in a motorcycle with a large restriction on the component arrangement space, a component arrangement space equivalent to a motorcycle without a mass damper can be secured.

In the present invention, the mass damper is suspended from the edge of the upper opening of the steering shaft . Therefore, when assembling the mass damper, the mass damper may be inserted from the upper opening of the steering shaft.

  Moreover, what is necessary is just to extract a mass damper from the upper opening of a steering shaft, when removing a mass damper. Since the mass damper can be attached and detached, maintenance of the mass damper can be improved.

  Moreover, what is necessary is just to extract a mass damper from the upper opening of a front fork when removing a mass damper. Since the mass damper can be attached and detached, maintenance of the mass damper can be improved.

In the invention according to claim 2 , a rubber orifice member is attached to the mouth of the fluid passage opened at both ends of the weight. When the weight swings up and down and reaches the rising end or the falling end, rubber orifice members provided at both ends of the weight hit the upper end or lower end of the cylinder, so that the shock applied to the weight can be alleviated. . As a result, it becomes possible to improve the durability of the mass damper.

  Further, by changing the orifice diameter of the orifice member, the flow rate of the fluid flowing through the fluid passage can be easily changed. As a result, the damper characteristics can be easily changed. In addition, the rubber orifice member is easier to attach and detach than the metal member, and the orifice member can be attached and detached quickly.

In the invention which concerns on Claim 3 , at least one part of a weight is arrange | positioned inside a coil spring. That is, since at least a part of the weight is disposed so as to overlap the coil spring, the vertical length of the mass damper can be suppressed. As a result, the mass damper can be made compact.

In the invention which concerns on Claim 4 , the outer cylinder of a mass damper has an outer peripheral surface and a contact surface. The mass damper was inserted from the upper opening, and the contact surface was placed on the upper opening of the steering shaft so that it was suspended. Thus, since the outer cylinder is arranged to be suspended from the steering shaft, the mass damper can be easily attached and detached. As a result, the maintainability of the mass damper can be improved.

In the invention which concerns on Claim 5 , a mass damper is set so that the vibration of 15 Hz or more and 25 Hz or less may be absorbed. Low frequency vibrations that occur in the vehicle at the early and late stages of the turn are generally around 20 hertz. Since the characteristics of the mass damper are set so as to reduce such low-frequency vibration (15 Hz to 25 Hz) that occurs during turning, low-frequency vibration during turning can be suitably suppressed.

In the invention which concerns on Claim 6 , the O-ring is attached to the lower part of the outer cylinder of a mass damper. The lower part of the outer cylinder is supported on the steering shaft by an O-ring. As a result, the lower part of the mass damper can be reliably supported while keeping the cost increase low.

In the invention according to claim 7, when the temperature of the mass damper rises and the pressure in the mass damper rises, the fluid is released to the fluid reservoir through the communication hole, and the piston of the pressure adjusting mechanism is pressed against the spring to communicate with the communication hole. Move to the opposite side.

  On the other hand, when the temperature of the mass damper decreases and the pressure in the mass damper decreases, the fluid returns from the fluid reservoir to the mass damper through the communication hole, and the piston of the pressure adjusting mechanism is pressed by the spring and moves toward the communication hole. Is done. As described above, the pressure adjustment mechanism is attached to the mass damper, and when the temperature of the mass damper rises, an excessive pressure change in the mass damper can be suppressed by allowing the fluid to escape to the fluid pool through the communication hole. .

1 is a left side view of a motorcycle according to the present invention. FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. It is principal part sectional drawing of a mass damper. It is a figure explaining the attachment structure of a mass damper. It is operation | movement explanatory drawing of a mass damper. It is a diagram explaining the axial displacement of a steering shaft and the swing of a weight. It is an effect | action figure of the mass damper which concerns on an Example and a comparative example. FIG. 6 is a cross-sectional view of a main part of a mass damper according to a second embodiment. 6 is a cross-sectional view of a main part of a mass damper according to Embodiment 3. FIG.

  Hereinafter, embodiments of the present invention will be described in detail. In the drawings and examples, “up”, “down”, “front”, “rear”, “left”, and “right” respectively indicate directions viewed from the driver who rides the motorcycle.

A first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the motorcycle 10 is provided with a front wheel 13 at a front portion of a body frame 11, a rear wheel 14 at a rear portion of the body frame 11, and an engine 15 between the front wheel 13 and the rear wheel 14. This is a saddle-ride type vehicle in which a seat 16 on which an occupant sits is provided between a front wheel 13 and a rear wheel 14 and the occupant rides over the seat 16.

  The vehicle body frame 11 includes a head pipe 21 constituting a front end thereof, main frames 22L and 22R extending from the head pipe 21 toward the rear of the vehicle (only the reference numeral 22L on the front side in the figure is shown), and main frames 22L and 22R. Pivot frames 24L and 24R connected to the rear end portion and extending downward to support the pivot shaft 23 (only the reference numeral 24L on the front side of the figure is shown), a cross frame 26 extending in the vehicle width direction to the pivot frames 24L and 24R, Seat rails 28L, 28R (only the reference numeral 28L on the front side of the figure is shown) that supports the seat 16 on which the driver sits from the upper part of the pivot frames 24L, 24R, and below the seat rails 28L, 28R, Each is passed between the rear of the seat rails 28L, 28R and the pivot frames 24L, 24R. Braille 29L, consisting a 29R (shown only the viewer's side of the drawing symbols 29L.).

  A steering shaft 31 serving as a hollow shaft is rotatably provided on the head pipe 21, and a top bridge 33 and a bottom bridge 34 are respectively attached to an upper end and a lower end of the steering shaft 31. A front fork 35 is attached to the front and rear.

  The front fork 35 extends obliquely forward and downward, a front wheel axle 37 is passed to the lower end of the front fork 35, and the front wheel 13 is rotatably supported by the front wheel axle 37. A steering handle 36 is attached to the top bridge 33. A so-called inverted type is adopted for the front fork 35. A front fender 41 that covers the front wheel 13 is attached to the front fork 35.

  A radiator unit 42 is provided between the front fork 35 and the engine 15. The radiator unit 42 has an upper end attached to the main frames 22 </ b> L and 22 </ b> R and a lower end attached to the engine 15. Here, the front fork 35 has left and right fork members that support both ends of the front wheel axle 37 that supports the front wheel 13. Hereinafter, these left and right fork members are referred to as left and right front forks 35L and 35R (only the reference numeral 35L on the front side is shown).

  The engine 15 is suspended between the main frames 22L and 22R and the pivot frames 24L and 24R below the main frames 22L and 22R. A fuel tank 27 is supported by main frames 22L and 22R located in front of the seat 16 and above the engine 30.

  The front end of the swing arm 44 is swingably attached to the pivot shaft 23 passed to the pivot frames 24L and 24R. A rear wheel axle 38 is passed to the rear end of the swing arm 44, and the rear wheel 14 driven by the engine 15 is rotatably supported on the rear wheel axle 38. The body frame 11 and the engine 15 are covered with a cowling 40.

  As shown in FIG. 2, the top bridge 33 is a member extending left and right in the vehicle width direction, and upper ends 45L and 45R of the left and right front forks are fixed at left and right ends thereof. A steering shaft 31 is disposed integrally with the top bridge 33 at the center of the top bridge 33 in the vehicle width direction, and a cap member 46 is attached to the upper end of the steering shaft 31. The cap member 46 covers the upper portion of the steering shaft 31. The mass dampers arranged in the steering shaft will be described in the following figures.

Next, the internal structure of the head pipe will be described.
As shown in FIG. 3, a first bearing 51 is fitted to the upper end of the cylindrical head pipe 21, and a second bearing 52 is fitted to the lower end of the head pipe 21, and the first bearing 51 and the second bearing 52 are Inside, the steering shaft 31 is rotatably supported by the head pipe 21.

  A top bridge 33 is attached to the upper end of the steering shaft 31 inserted into the head pipe 21 so that the head pipe 21 is sandwiched from above and below, and a bottom bridge 34 is attached to the lower end of the steering shaft 31.

  The steering shaft 31 has a stepped portion 54 extending radially outward at a lower end 32 protruding downward from the head pipe 21. This step portion 54 is hooked on the lower end of the bottom bridge 34, and a fastening nut 57 is screwed into a male screw portion 56 formed on the upper portion of the steering shaft 31, so that the top bridge 33 and the bottom bridge 34 are clamped in the axial direction of the steering shaft 31. By fastening in this manner, the top bridge 33 and the bottom bridge 34 are integrated with the steering shaft 31. A front fork 35 is attached to the top bridge 33 and the bottom bridge 34 so as to penetrate the top bridge 33 and the bottom bridge 34.

  A mass damper 60 is disposed inside the steering shaft 31. The mass damper 60 has a cylindrical shape. The mass damper 60 includes a weight 61 and an elastic member (coil springs 66, 66) that supports the weight 61 from above and below the weight 61 as main elements. When the vehicle turns, the weight 61 swings in a direction to cancel the vibration, thereby absorbing the vibration generated in the front portion of the vehicle body.

  The mass damper 60 is inserted from the upper opening 71 of the steering shaft 31, as will be described later. The upper opening 71 of the steering shaft 31 into which the mass damper 60 is inserted is closed with a cap 74 having a flange 73 having a bowl-like upper end. In FIG. 2, the cap 74 is fastened to the upper surface of the fastening nut 57 by three screws 75 arranged on the flange 73. The detailed structure of the mass damper will be described with reference to the next figure.

  As shown in FIG. 4, the mass damper 60 includes a bottomed outer cylinder 81 having a bottom 82 at the lower end, and a lower coil spring 68 inserted into the outer cylinder 81 to a position where it abuts on the bottom 82 of the outer cylinder 81. A weight 61 inserted into the outer cylinder 81 to a position where it abuts on the upper end of the lower coil spring 68, an upper coil spring 67 inserted into the outer cylinder 81 to a position where it abuts on the upper portion of the weight 61, and an outer cylinder The main element is a cap 74 that is inserted into the upper end of the upper coil spring 67 and closes the upper opening 83 of the outer cylinder 81.

  The weight 61 includes a first weight 62 provided substantially at the center of the mass damper 60 in the height direction, an upper second weight 63 connected and fixed to the first weight 62 from above, and a lower weight connected to the first weight 62. It consists of a lower second weight 64 to be fixed. The first weight 62, the upper second weight 63, and the lower second weight 64 are respectively formed with fluid passages 92, 93, 94 along the axial direction of the weight movement direction. A rubber upper orifice member 95 is attached to the upper end of the upper second weight 63 so as to fit, and a rubber lower orifice member 96 is attached to the lower end of the lower second weight 64. It has been. The upper and lower orifice members 95 and 96 made of rubber have upper and lower orifices 97 and 98, respectively, and the upper and lower orifices 97 and 98 communicate with the fluid passages 92, 93, and 94, respectively. The upper and lower orifices 97 and 98 are portions having a smaller cross-sectional area than the cross-sectional area of the fluid passage 92 (or the fluid passage 93 or the fluid passage 94), and restrict the flow of fluid.

  That is, the fluid passage 90 is formed in the weight 61 along the moving direction of the weight 61, and the fluid passage ports 103 and 104 opened at both ends of the weight 61 (the upper second weight 63 and the lower second weight 64). In addition, rubber orifice members (upper orifice member 95 and lower orifice member 96) having upper and lower orifices 97 and 98, respectively, are attached.

Next, the pressure adjustment mechanism will be described.
The cap 74 has a cylindrical fluid reservoir 112 having a communication hole 111 communicating with the inside of the outer cylinder (in the figure, the volume of the fluid reservoir 112 is occupied by a piston 113 described later and is zero), and is a mass damper. When the inside is filled with a fluid such as oil, a fluid reservoir 112, a piston 113 slidable in the fluid reservoir 112, a spring 114 that presses the piston 113 toward the orifice, and a lid 115 that presses the spring 114. Thus, the pressure adjusting mechanism 110 that maintains the pressure of the fluid in the mass damper 60 at a predetermined pressure is configured. The cap 74 is provided with a pressure adjustment mechanism 110.

  When the temperature of the mass damper 60 rises and the pressure in the mass damper rises, the fluid flows into the fluid reservoir 112 through the communication hole 111 and presses the piston 113 of the pressure adjustment mechanism 110 against the spring 114 to communicate with the communication hole. It is moved upward in the direction opposite to 111. On the other hand, when the temperature of the mass damper 60 decreases and the pressure in the mass damper decreases, the fluid flows out of the fluid reservoir 112 through the communication hole 111, and the piston 113 of the pressure adjustment mechanism 110 is pressed by the spring 114 and is connected to the communication hole. It is moved in the direction of 111. Thus, since the pressure adjustment mechanism 110 is attached to the mass damper 60, even when the temperature of the mass damper 60 changes, the characteristics of the mass damper 60 can be maintained constant.

  The upper second weight 63 constituting a part of the weight is disposed inside the upper coil spring 67. Further, the lower second weight 64 is disposed inside the lower coil spring 68. At least a part of the weight 61 is disposed inside a coil spring 66 (an upper coil spring 67 and a lower coil spring 68) as an elastic member. That is, since at least a part of the weight is disposed so as to overlap with the coil spring 66, the vertical length of the mass damper 60 can be suppressed by the amount of overlap. As a result, the mass damper 60 can be kept compact in the axial direction.

Next, the mass damper mounting structure of the present invention will be described.
As shown in FIG. 5, the mass damper 60 is inserted from an upper opening 71 opened at the top of the steering shaft 31 and is attached to be suspended from an edge 72 of the upper opening. Specifically, the mass damper 60 in which the upper opening 83 of the outer cylinder 81 is closed with a cap 74 is inserted from the upper opening 71 of the round cylindrical steering shaft 31 and is suspended from the edge 72 of the upper opening. Installed.

  The mass damper 60 has an outer cylinder 81 that slidably supports a weight 61 on its inner surface, and the outer cylinder 81 is fitted on the inner peripheral surface 30 of the steering shaft and supports the outer cylinder 81 in the radial direction. 85 and an abutment surface 86 that is expanded outward from the outer peripheral surface 85 and abuts against the upper opening 71 of the steering shaft to support the outer cylinder 81 in the axial direction.

  The outer cylinder 81 of the mass damper has an outer peripheral surface 85 and a contact surface 86. The mass damper 60 was inserted from the upper opening 71 of the steering shaft, and the contact surface 86 was placed on the upper opening 71 of the steering shaft so as to be suspended.

  When assembling the mass damper 60, the mass damper 60 is inserted from the upper opening 71 of the steering shaft 31 as indicated by the arrow m, and the contact surface 86 of the outer cylinder 81 is applied to the edge 72 of the steering shaft 31. The outer cylinder 81 integrated with the cap 74 was inserted, and the mass damper 60 was formed on the upper surface of the fastening nut 57 via the three screws 75 and fastened to the screw 77. On the other hand, when removing the mass damper 60, the three screws 75 may be removed, and the mass damper 60 integrated with the cap 74 may be extracted from the upper opening 71 of the steering shaft. Since the detachability of the mass damper 60 is improved, the maintainability of the mass damper 60 can be improved.

  An O-ring 88 is attached to a lower portion 70 located near the bottom 82 of the outer cylinder between the outer cylinder 81 and the steering shaft 31. The lower portion 70 of the outer cylinder is supported on the steering shaft 31 by an O-ring 88 when the mass damper 60 is assembled in the steering shaft 31. As a result, the lower portion 70 of the mass damper can be reliably supported on the steering shaft 31 while suppressing an increase in cost.

The operation of the motorcycle described above will be described next.
In FIG. 6A, when the steering shaft 31 is not subjected to vibration in the axial direction, the mass damper weight 61 is in the neutral position.

  FIG. 6B shows that the steering shaft 31 receives a force in the axial direction, and the mass damper weight 61 is in a position moved in the axial direction of the steering shaft (the direction of the arrow b in the figure). At this time, the upper coil spring 67 acts on the weight 61 to return it to the neutral position in FIG. In addition, a force that prevents the fluid 61 from returning to the neutral position in FIG. 6A also acts on the weight 61 due to the resistance of the fluid flowing through the fluid passage 90, the upper and lower orifices 97, 98, and the fluid passage.

  FIG. 6C shows that the steering shaft 31 receives a force in the axial direction, and the mass damper weight 61 is in a position moved in the axial direction of the steering shaft (in the direction of arrow c). At this time, a force for returning the weight 61 to the neutral position in FIG. 6A acts on the weight 61 by the lower coil spring 68. In addition, a force that prevents the fluid 61 from returning to the neutral position in FIG. 6A also acts on the weight 61 due to the resistance of the fluid flowing through the fluid passage 90, the upper and lower orifices 97, 98, and the fluid passage.

  Rubber orifice members (upper and lower orifice members 95 and 96) are attached to the fluid passage ports 103 and 104 opened at both ends of the weight 61, respectively. The weight 61 swings up and down, the weight 61 reaches the rising end or the lowering end, and the upper and lower orifice members 95 and 96 provided at both ends of the weight 61 hit the cap 74 or the bottom 82 of the outer cylinder. The shock of the weight 61 is relieved. As a result, the durability of the mass damper 60 can be improved.

  Further, the fluid flowing through the fluid passage can be obtained by exchanging the orifice diameters of the upper orifice 97 and the lower orifice 98 respectively opened in the upper and lower orifice members 95 and 96 with the upper and lower orifice members 95 and 96 having different orifice diameters. The flow rate can be easily changed. As a result, the damper characteristic can be easily changed, and the optimum damper characteristic can be obtained quickly. In addition, the rubber orifice members 95 and 96 are easier to attach and detach than the metal members, and the orifice members 95 and 96 can be attached and detached quickly. With reference to the next figure, the action of the mass damper's weight swinging in response to the axial displacement of the steering shaft will be described.

  FIG. 7A is a graph showing the relationship between the axial displacement of the steering shaft and time, and FIG. 7B is a graph showing the relationship between the swing (displacement) of the weights constituting the mass damper and time. is there. FIG. 7A and FIG. 7B match the time axis, so that the relationship between the axial displacement of the steering shaft and the swing of the weight is explained. In the figure, the horizontal axis represents time, and the vertical axis represents displacement with the neutral point being zero. Hereinafter, description will be made with reference to FIGS. 6 (a) to 6 (c).

  In the initial state (S1) where the steering shaft (FIG. 6, reference numeral 31) does not swing, the weight 61 does not swing as shown in FIG. 6 (a). Next, when the steering shaft 31 is displaced downward as shown in S1 to S2 and reaches the maximum displacement at the S2 position, the weight 61 is lowered together with the steering shaft 31. The displacement of the weight 61 is at the position (W2) as it is in the initial state.

  Next, the steering shaft 31 rises rapidly from the displacement of S2 (S3). Then, the weight 61 rises rapidly together with the steering shaft 31, but the weight 61 does not swing (W3). At this time, since the weight 61 is not swung, the weight 61 acts to suppress the axial displacement of the steering shaft 31.

  Next, when the displacement of the steering shaft 31 is lowered from the displacement S3 to the displacement S4 through the initial position, the weight 61 is raised upward to the displacement W4 by its inertial force, as shown in FIG. 6B. . Subsequently, when the steering shaft 31 rises and reaches the next rising end S5, the displacement of the weight 61 reaches the lowering end of W5 as shown in FIG. 6 (c).

  Hereinafter, as the displacement of the steering shaft 31 is swung up and down with S6, S7, S8..., The displacement of the weight 61 is W6, W7, W8. Displace. That is, the weight 61 oscillates in the opposite phase to the characteristics of the steering shaft 31 and acts to attenuate the vibration generated in the steering shaft 31.

  The mass damper 60 is set to absorb vibrations of 15 hertz or more and 25 hertz or less. Low frequency vibrations that occur in the vehicle at the early and late stages of the turn are generally around 20 hertz. By disposing the mass damper 60 set in accordance with such low frequency vibration of 20 Hz, low frequency vibration (15 Hz or more and 25 Hz or less) generated during turning can be suitably suppressed.

Next, the effect | action of arrange | positioning a mass damper in the head pipe which becomes a dead space easily is demonstrated.
As shown in the embodiment of FIG. 8A, the mass damper 60 is disposed in the steering shaft 31.

  As shown in the comparative example of FIG. 8B, the mass damper 120 (120a, 120b, 120c) of the motorcycle 10X is disposed at the rear end of the swing arm 121, below the seat 16 on which the occupant sits, and / or at the rear of the vehicle body. May be. When the mass damper 120a is arranged at the rear end of the swing arm 121, there is a problem that the rear end of the swing arm 121 becomes bulky due to the mass damper 120a. Further, if the mass dampers 120b and 120c are arranged below the seat 16 and / or in the rear part of the vehicle body, there is a possibility that the arrangement space for other parts may be restricted.

  In FIG. 8A, in the present invention, a mass damper 60 is disposed in the steering shaft 31. When the mass damper 60 is disposed at the front of the vehicle body, it is not necessary to dispose the mass damper outside the front fork 35. Since the mass damper 60 is arranged in the head pipe, there is no concern that the layout of other parts will be hindered, and it is not necessary to newly secure an arrangement space for the mass damper 60. As a result, the mass damper 60 can be disposed in a place where a dead space is likely to occur.

  That is, in the present invention, since the mass damper 60 is disposed in the space inside the existing steering shaft 31, the vibration of the front portion of the vehicle can be reduced without affecting the component layout of the front portion of the vehicle.

A second embodiment of the present invention will be described with reference to the drawings. In the figure, the head pipe is omitted.
As shown in FIG. 9, the mass damper 60B includes a lower coil spring 68B that is inserted into the bottom portion 82B of the steering shaft 31, and a weight 61B that is inserted into the steering shaft 31 so as to contact the upper end of the lower coil spring 68B. An upper coil spring 67B inserted into the steering shaft 31 so as to contact the upper part of the weight 61B and a cap 74B that closes the upper opening 71 of the steering shaft 31 so as to contact the upper end of the upper coil spring 67B are mainly used. Elements.

  The major difference from the first embodiment is that the mass damper 60B is not provided with an outer cylinder, and the lower coil spring 68B, the upper coil spring 67B and the weight 61B are directly inserted into the steering shaft 31B, and a liquid such as oil. The fluid is not sealed and the cap is not provided with a pressure adjusting mechanism. There were no significant differences in other functions and effects, and the same functions and effects as in Example 1 were obtained.

A third embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 10, a mass damper 60C is disposed inside the upper portion of the left front fork 35L. The mass damper 60C has a cylindrical shape and includes a weight 61C and an elastic member (coil spring 66C) that supports the weight 61C. The mass damper 60C absorbs vibration generated at the front of the vehicle body as the weight 61C moves.

  In the structure of the mass damper, the third embodiment differs greatly from the first embodiment in that it is arranged not inward of the steering shaft but inward of the upper portion of the front fork, and because of the space limitation of the front fork, This is the point that the length of the coil spring is shortened, and there is no other significant difference, and the explanation is omitted.

  The mass damper 60 </ b> C is disposed above the spring 131 that constitutes the pair of left and right front forks 35, and is attached so as to be suspended from an edge 123 </ b> C of the upper opening opened at the top of the pair of left and right front forks 35.

  In the drawing, the internal structure of the left front fork 35L has been described, but the internal structure of the right front fork 35R is the same. That is, the mass damper built in the right front fork 35R is the same as the left front fork 35L, and the description thereof is omitted.

  In the third embodiment, the mass damper is disposed above the spring 131 that constitutes the pair of left and right front forks. However, the mass damper may be disposed below the spring 131 of the front fork. In addition, mass dampers may be provided on both the left and right pair of front forks and the steering shaft.

  Although the present invention is applied to a motorcycle in the embodiment, it can also be applied to a tricycle and can be applied to a general vehicle.

  The present invention is suitable for a motorcycle in which a mass damper is disposed at the front of the vehicle body.

  DESCRIPTION OF SYMBOLS 10 ... Motorcycle, 11 ... Body frame, 13 ... Front wheel, 14 ... Rear wheel, 15 ... Engine, 21 ... Head pipe, 30 ... Inner surface of steering shaft, 31 ... Steering shaft, 35L, 35R ... Left and right front forks , 60 ... mass damper, 61 ... weight, 66 ... elastic member (coil spring) 71 ... upper opening of the steering shaft, 72 ... edge of the steering shaft, 74 ... cap, 81 ... outer cylinder, 85 ... outer peripheral surface of the mass damper, 86 ... Abutting surface of mass damper, 88 ... O-ring, 95 ... Orifice member (upper orifice member), 96 ... Orifice member (lower orifice member), 103 ... Port of fluid passage (upper second weight port) 104 ... Fluid passage port (lower second weight port), 110 ... Pressure adjusting mechanism, 111 ... Communication hole, 112 ... Fluid pool 113 ... piston 114 ... spring 131 ... elastic member (spring).

Claims (7)

A vehicle body frame (11), a front wheel (13) provided at the front part of the vehicle body frame (11), a rear wheel (14) provided at the rear part of the vehicle body frame (11), the front wheel (13) and the rear wheel An engine (15) provided between the wheels (14), a head pipe (21) provided at the front end of the vehicle body frame (11), and a steering shaft (31) rotatably provided on the head pipe (21) ) And a pair of left and right front forks (35L, 35R) provided integrally with the steering shaft (31) and supporting the front wheel (13),
The head pipe (21) includes a weight (61) and an elastic member (66) that supports the weight (61). The weight (61) moves to move the weight (61) to absorb vibration. mass damper (60) is arranged,
The mass damper (60) is suspended from an edge (72) of the upper opening (71) of the steering shaft (31) ,
Motorcycle characterized by that. A fluid passageway (90) is formed in the weight (61) along the moving direction of the weight (61),
The motorcycle according to claim 1 , characterized in that rubber orifice members (95, 96) are attached to the mouths (103, 104) of the fluid passages opened at both ends of the weight (61). The said elastic member is a coil spring (66), Comprising: At least one part of the said weight (61) is arrange | positioned inside the said coil spring (66), The Claim 1 or 2 characterized by the above-mentioned. The described motorcycle. The mass damper (60) has an outer cylinder (81) inserted into the steering shaft (31) and slidably supporting the weight (61) inside the mass damper (60).
The outer cylinder (81) is fitted to the inner peripheral surface (30) of the steering shaft and supports an outer peripheral surface (85) for supporting the outer cylinder (81) in the radial direction, and extends outward from the outer peripheral surface (85). 4. The contact surface according to claim 1, wherein the contact surface has a diameter and a contact surface (86) that contacts the upper opening (71) and supports the outer cylinder (81) in the axial direction. 5. Motorcycle. The motorcycle according to any one of claims 1 to 4 , wherein the mass damper (60) is set to absorb vibrations of 15 Hz to 25 Hz. The motorcycle according to claim 4 , wherein an O-ring (88) is attached to a lower portion of the outer cylinder (81) between the outer cylinder (81) and the steering shaft (31). The upper end of the outer cylinder (81) is closed with a cap (74),
The cap (74) has a cylindrical fluid reservoir (112) having a communication hole (111) communicating with the outer cylinder (81).
When the mass damper (60) is filled with fluid, the fluid reservoir (112), a piston (113) slidable in the fluid reservoir (112), and the piston (113) are connected to the communication hole. (111) out with spring (114) for pressing the side, according to claim 4, characterized in that the pressure of fluid in the mass damper (60) constitutes a pressure regulating mechanism (110) to maintain a predetermined pressure or The motorcycle according to claim 6 .

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