Patent Publication Number: US-6981712-B2

Title: Body frame damping structure in a saddle-type vehicle

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field of the Invention 
   The present invention relates to a body frame damping structure in a saddle-type vehicle disposed with a damping force generating means that is disposed so as to bridge portions of the body frame with other portions of the body frame. With the damping force generating means being respectively coupled, the portions and the other portions are elastically deformed when an impact force is applied to the body frame by the road surface. 
   2. Prior Art 
   Conventionally, there are saddle-type vehicles. A vehicle is disposed with a body frame configuring a frame of the vehicle body, a front fork steerably supported at a front end portion of the body frame, a front wheel supported at lower end portions of the front fork, a rear arm pivotally supported by a pivot support shaft at a rear portion of the body frame so as to be swingable up and down, a rear wheel supported at a swinging end of the rear arm, and dampers included inside the front fork and disposed so as to bridge the body frame and the rear arm. 
   The body frame is disposed with a head pipe that configures the front end portion of the body frame and supports the front fork, a frame body that extends rearward and downward from the head pipe and supports the rear arm at extension portions of the frame body, a seat bracket that extends rearward from the frame body and supports a seat, and an internal combustion engine that is supported at the frame body and is interlocked and coupled with the rear wheel. The body frame is supported on a traveling road surface by the front and rear wheels. 
   At the time the vehicle is traveling due to driving of the internal combustion engine, an impact force is applied to the body frame from the traveling road surface via the front and rear wheels, regardless of the presence of the dampers. Here, because it is difficult for the impact force applied to the body frame from the traveling road surface to be damped by the body frame itself when the rigidity of the body frame is too high, the vehicle tends to travel while bouncing from the traveling road surface each time the impact force is applied to the body frame. However, this action of the vehicle is not preferable in terms of the steering stability. 
   Thus, the body frame is usually made elastically deformable to a certain extent, whereby the impact force is damped so that steering stability is satisfactorily maintained when the impact force is applied to the body frame. 
   Incidentally, because the vehicle is of a saddle-type, the constituent parts of the vehicle are disposed compactly to make the vehicle smaller in terms of the function of the vehicle, and there is a demand to make the vehicle lighter. For this reason, it is not easy to ensure sufficient strength and rigidity for the portions of the body frame. For instance, when the vehicle is used for racing and a large impact force (kickback) is instantaneously applied to the body frame during high-speed travel, there is the potential for elastic deformation of the body frame to become large, and this large deformed state tends to persist, which also hinders steering stability and is not preferable. 
   Also, the cross section of the rear arm is made into a box-like shape and an interior space thereof is filled with polyurethane foam, whereby high rigidity is secured for the rear arm of the vehicle body and vibrational sound is reduced. 
   Incidentally, because the foam has compression strength, in a case where the rear arm is elastically deformed by an impact force, it is conceivable for the foam to work, with respect to elastic deformation in which the cross-sectional area of the rear arm is compressed, to counter this compression so that the elastic deformation is suppressed and satisfactory steering stability is maintained. However, because the foam does not include tensile strength, it is difficult for the foam to work against elastic deformation in which the cross-sectional area of the rear arm expands, so that this elastic deformation cannot be sufficiently suppressed. Thus, the above-described configuration is insufficient in terms of maintaining satisfactory steering stability by suppressing elastic deformation of the body frame resulting from the impact force. 
   Moreover, in terms of the properties of the foam, it is also conceivable for the working of the foam in terms of strength to be insufficient simply by applying the foam to outer surface sides of the body frame. Thus, the cross section of the body frame is made into the box-like shape and the interior space of the rear arm is filled with the foam. However, when the foam is disposed in this manner, a constraint is placed on the cross-sectional shape of the body frame and molding of the body frame tends to become cumbersome. 
   The present invention was devised in light of the above-described circumstances, and it is an advantage thereof to ensure that, in a case where an impact force applied to a body frame from a traveling road surface during travel of a vehicle is to be damped by elastic deformation of the body frame, the body frame is deterred from greatly elastically deforming so that the steering stability can be satisfactorily maintained when a large impact force is applied to the body frame. It is also an advantage of the invention to ensure that molding of the body frame can be achieved easily, even in such a case. 
   SUMMARY OF THE INVENTION 
   A body frame damping structure in a saddle-ridden vehicle of the invention for solving the above-described problem is as follows. 
   As exemplified in all of the drawings the invention of a body frame damping structure in a saddle-type vehicle includes a front fork steerably supported at a front end portion of a body frame; a front wheel supported at lower end portions of the front fork; a rear arm pivotally supported at a rear portion of the body frame by a pivot support shaft so as to be swingable up and down; and a rear wheel supported at a swinging end of the rear arm. 
   Damping force generating means are disposed so as to bridge portions of the body frame with other portions of the body frame, with the damping force generating means being respectively coupled to the portions and the other portions. 
   As exemplified in all of the drawings, the body frame includes a head pipe, which configures the front end portion of the body frame and supports the front fork, and a frame body, which extends rearward and downward from the head pipe and pivotally supports the rear arm at extension portions of the frame body. The frame body is disposed with linear portions that extend substantially straightly and 
   the damping force generating means are disposed at outward vicinities of the linear portions so as to extend along the linear portions. 
   The frame body includes a pair of left and right frame bodies and the damping force generating means is disposed so as to extend in a width direction of the vehicle and bridge the left and right frame bodies, with the damping force generating means being coupled to the frame bodies. 
   According to another embodiment of the present invention, a body frame damping structure in a saddle-type vehicle includes a front fork steerably supported at a front end portion of a body frame; a front wheel supported at lower end portions of the front fork; a rear arm pivotally supported at a rear portion of the body frame by a pivot support shaft so as to be swingable up and down; and a rear wheel supported at a swinging end of the rear arm. The body frame includes a head pipe, which configures the front end portion of the body frame and supports the front fork, a frame body, which extends rearward and downward from the head pipe and pivotally supports the rear arm at extension portions of the frame body, and a seat bracket, which projects rearward from the frame body and supports a seat. 
   The damping force generating means are disposed so as to bridge the frame body and the seat bracket, with the damping force generating means being respectively coupled to the frame body and the seat bracket. 
   According to another embodiment of the present invention, a body frame damping structure in a saddle-type vehicle includes a front fork steerably supported at a front end portion of a body frame; a front wheel supported at lower end portions of the front fork; a rear arm pivotally supported at a rear portion of the body frame by a pivot support shaft so as to be swingable up and down; and a rear wheel supported at a swinging end of the rear arm. The body frame includes a head pipe, which configures the front end portion of the body frame and supports the front fork, a frame body, which extends rearward and downward from the head pipe and pivotally supports the rear arm at extension portions of the frame body, and an internal combustion engine, which is supported at the frame body and is interlocked and coupled with the rear wheel. 
   The damping force generating means are disposed so as to bridge the frame body and the internal combustion engine, with the damping force generating means being respectively coupled to the frame body and the internal combustion engine. 
   As exemplified in all of the drawings, the damping force generating means damp an impact force applied in one direction to the damping force generating means and an impact force applied in a direction opposite to the one direction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a first embodiment of the present invention. 
       FIG. 2  illustrates a side view of the entire vehicle according to the first embodiment of the present invention. 
       FIG. 3  illustrates the first embodiment of the present invention taken along line  3 — 3 . 
       FIG. 4  illustrates a partially enlarged cross-sectional view of  FIG. 3 . 
       FIG. 5  illustrates a second embodiment of the present invention. 
       FIG. 6  illustrates a partially enlarged view of  FIG. 5  and a view corresponding to  FIG. 1 , according to the second embodiment of the present invention. 
       FIG. 7  illustrates a view corresponding to  FIG. 3  according to the second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the invention will be described below with the drawings. 
   (First Embodiment) 
     FIGS. 1 to 4  show a first embodiment of the invention. 
   In  FIGS. 1 to 3 , reference numeral  1  is a saddle-type vehicle exemplified by a two-wheeled motor vehicle, and arrow Fr represents a front direction thereof. 
   The vehicle  1  is disposed with a body frame  3  configuring a frame of a vehicle body  2 ; a front fork  6  that is supported at a front end portion of the body frame  3  so as to be steerable around a steering axis center  4  and includes a damper  5 ; a front wheel  8  that is rotatably supported at lower end portions of the front fork  6  by an axle  7 ; and an unillustrated steering handle that is supported at an upper end portion of the front fork  6 . 
   The vehicle  1  is also disposed with a rear arm  10  that is made of a metal plate, disposed rearward of a lower portion of the body frame  3  and extends in a front-rear direction, with a front end portion of the metal plate rear arm  10  being pivotally supported at a rear lower portion of the body frame  3  by a pivot support shaft  9  so that a rear portion of the rear arm  10  is swingable up and down; a rear wheel  12  that is rotatably supported at the swinging end portion of the rear arm  10  by an axle  11 ; a link mechanism  13  disposed so as to bridge the rear lower portion of the body frame  3  and a front portion of the rear arm  10 ; and a damper  14  disposed so as to bridge a rear upper portion of the body frame  3  and the link mechanism  13 . Each of the dampers  5  and  14  is of a cylinder format using a fluid. The body frame  3  is supported on a traveling road surface  15  by the front and rear wheels  8  and  12 , whereby the vehicle  1  can travel forward. 
   The body frame  3  is disposed with a head pipe  18  that configures the front end portion of the body frame  3  and supports the front fork  6 ; a pair of left and right frame bodies  19  that are made of metal plates, extend rearward and downward from the head pipe  18  and pivotally support, with the pivot support shaft  9 , the rear arm  10  at extension portions of the frame bodies  19 ; and upper and lower cross members  20  and  21  that join mutual extension portions of the left and right frame bodies  19 . The cross section of each frame body  19  in a longitudinal direction thereof has a long box-like shape. 
   Each frame body  19  is disposed with a main frame  22 , which extends substantially straightly rearward and downward from the head pipe  18  when the vehicle body  2  is seen from the side ( FIGS. 1 and 2 ), and a rear arm bracket  23 , which configures the extension portion of the frame body  19  and integrally extends rearward and downward from an extension end portion of the main frame  22 . The depression angle of the rear arm bracket  23  is larger than the rearward depression angle of the main frame  22 . In other words, a joint portion at which the main frame  22  and the rear arm bracket  23  are mutually joined is formed as a curved portion. Also, when the vehicle body  2  is seen in plan view ( FIG. 3 ), each main frame  22  has a curved shape that extends rearward and outward from the head pipe  18  and then extends substantially straightly rearward to become outwardly convex when the vehicle body  2  is seen in plan view. 
   Mutual upper portions and lower portions of the left and right rear arm brackets  23 ,  23  are respectively joined by the upper and lower cross members  20  and  21 . The front end portion of the rear arm  10  is pivotally supported by the pivot support shaft  9  at intermediate portions, in the vertical direction, of the rear arm brackets  23 ,  23 . One end portion of the link mechanism  13  is pivotally supported at the extension end portions (lower end portions) of the rear arm brackets  23 ,  23 . 
   The body frame  3  is disposed with a seat bracket  26  that projects rearward and upward from the joint portions at which the main frames  22  and the rear arm brackets  23  are joined. A front end portion of the seat bracket  26  is fastened by fasteners  27  to the joint portions and cantilever-supported at the rear portion of the frame bodies  19  of the body frame  3 , whereby a seat  28  is supported at the seat bracket  26 . Foot rests  29  are disposed below a front end portion of the seat  28 . The foot rests  29  are supported by brackets  30  at intermediate portions in the vertical direction of the rear arm brackets  23 . A rider seated saddle-style in the seat  28  can place his/her feet on the foot rests  29 , so that the rider can grip the handle in this posture. 
   A traveling drive-use drive device  33  of the vehicle  1  is disposed below the left and right main frames  22 ,  22  of the body frame  3 . The drive device  33  is disposed with an internal combustion engine  34 , which configures a front portion of the drive device  33 , a power transmission device  35 , which is positioned rearward of the internal combustion engine  34  and connected to the internal combustion engine  34 , and unillustrated interlocking means such as a chain, which interlocks and couples the rear wheel  12  to the power transmission device  35 . 
   An upper portion of the internal combustion engine  34  is supported by fasteners  36 ,  36  at intermediate portions, in the front-rear direction, of the main frames  22  of the frame bodies  19 . A rear portion of the power transmission device  35  is supported by fasteners  37  and  38  at upper and lower end portions of the rear arm brackets  23  of the frame bodies  19 . Thus, the internal combustion engine  34  is supported by the frame bodies  19  of the body frame  3 . The internal combustion engine  34  itself has sufficient strength and rigidity and is supported so as to straddle the main frames  22  and the rear arm brackets  23  of the frames bodies  19  in the body frame  3 . For this reason, the internal combustion engine  34  configures part of the body frame  3 . 
   A fuel tank  40  is supported above the main frames  22  of the body frame  3 , and fuel inside the fuel tank  40  is supplied to the internal combustion engine  34  of the drive device  33 .  41  is a cowling. 
   In  FIGS. 1 to 4 , a pair of left and right damping force generating means  44 ,  44 , which extend in the front-rear direction and bridge portions  3   a  (front portions) and other portions  3   b  (rear portions) of outer surface sides of the frame bodies  19  in the body frame  3 , with front and rear end portions that are end portions being respectively coupled by couplers  42  and  43  to the portions  3   a  and the other portions  3   b , are disposed. The damping force generating means  44  can dampen an impact force that is applied to the body frame  3  and causes the portions  3   a  and other portions  3   b  to relatively elastically deform so that the portions  3   a  and the other portions  3   b  move towards and away from each other. The damping force generating means  44  are cylinder-format dampers that use a fluid (oil). The damping force generating means  44  extend substantially straight and have the same shape and the same size. When an impact force is applied in one direction (tensile direction) that is the axial direction of the damping force generating means  44 , or when an impact force is applied in the direction (compression direction) opposite to the one direction, the damping force generating means  44  extend or contract in the axial direction. In other words, the damping force generating means  44  can dampen the impact force by extending and contracting. 
   Each coupler  42  and  43  is disposed with a bracket  47 , which is fastened by a fastener  46  and supported at outer side surfaces of the frame bodies  19 , and a pivot support shaft  48 , which pivotally supports the end portions of each damping force generating means  44  at the brackets  47 . Each of the damping force generating means  44  is disposed with a cylinder tube  50 , which configures an end portion of the damping force generating means  44  and is coupled to the other portions  3   b  of the frame bodies  19  by the couplers  43 ; an unillustrated piston, which is fitted in the cylinder tube  50  so as to be movable in an axial direction; and a piston rod  51 , which extends from the piston to the outside of the cylinder tube  50 , configures another end portion of the damping force generating means  44 , and is coupled to the portions  3   a  of the frame bodies  19  by the couplers  42 . Two pressure oil chambers that are partitioned by the piston inside the cylinder tube  50  communicate with each other through an orifice. 
   When a driving force of the internal combustion engine  34  is transmitted via the power transmission device  35  to the rear wheel  12  by the driving of the internal combustion engine  34  of the drive device  33 , it is possible for the vehicle  1  to travel forward on the traveling road surface  15 . Although an impact force is applied to the body frame  3  from the traveling road surface  15  while the vehicle is traveling, via the front and rear wheels  8  and  12 , the front fork  6  including the damper  5 , the rear arm  10 , the link mechanism  13  and the damper  14 , the impact force applied to the body frame  3  is alleviated by the dampers  5  and  14 . 
   When the frame bodies  19  of the body frame  3  are elastically deformed (0.1 to 0.2 mm) by the impact force applied to the body frame  3 , so as to extend and contract in the front-rear direction (longitudinal direction), and the portions  3   a  and the other portions  3   b  move towards and away from each other, the damping force generating means  44  disposed so as to bridge the frame bodies  19  extend and contract in accompaniment therewith, and the following “action and effects” arise. 
   That is, “action and effects” arise in that, when the damping force generating means  44  extend and contract, oil flows through the orifice from one of the two pressure oil chambers in each of the cylinder tubes  50  of the damping force generating means  44  to the other chamber, whereby the impact force is damped and each frame body  19  is deterred from being largely elastically deformed frontward and rearward by a reaction force generated in the longitudinal direction of the damping force generating means  44 . 
   Thus, “action and effects” arise in that, for example, when a large impact force is applied to the body frame  3  from the traveling road surface  15  at the time of high-speed cornering in a race, the frame bodies  19  of the body frame  3  try to largely elastically deform in the saddle-type vehicle  1  for which compactness and lightness are demanded. This elastic deformation however, is prevented by the working of the damping force generating means  44  and a sense of being one with the vehicle  1  is ensured for the rider. In other words, as described above, even when the impact force on the body frame  3  is large, steering stability is satisfactorily maintained. 
   Portions of the frame bodies  19  configuring the rear portions of the main frames  22  are linear portions  19   a  that extend substantially straightly and three-dimensionally. At least one portion of each of the damping force generating means  44  is disposed at lower outward vicinities of the linear portions  19   a  so as to extend substantially parallel to and along the linear portions  19   a.    
   For this reason, as described above, even if the damping force generating means  44  are disposed so that steering stability is satisfactorily maintained, the damping force generating means  44  are prevented from projecting largely outward from the frame bodies  19  of the body frame  3 , these  19  and  44  are disposed compactly, and the vehicle body  2  is prevented from becoming large. 
   Here, the portions  3   a  of the frame bodies  19  of the body frame  3  are positioned near support portions of the internal combustion engine  34  of the drive device  33 , and the other portions  3   b  are positioned near pivot support portions of the rear arm  10 . The support portions of the internal combustion engine  34  of the drive device  33  are portions at which the impact force from the drive device  33  is inputted. The pivot support portions of the rear arm  10  are portions at which the impact force is inputted from the rear wheel  12 . Moreover, portions of the frame bodies  19  between the portions  3   a  and the other portions  3   b  include the curved portions. 
   For this reason, the portions of the frame bodies  19  between the portions  3   a  and the other portions  3   b  tend to be elastically deformed by the impact force, so that they bend up and down and left and right. In other words, the portions  3   a  and the other portions  3   b  tend to be elastically deformed so that they move towards and away from each other. However, the damping force generating means  44  disposed so as to bridge the frame bodies  19  extend and contract with the elastic deformation, whereby the “action and effects” are more reliably achieved. 
   Because the damping force generating means  44  are disposed at the outer sides of the frame bodies  19  and are disposed so as to bridge the frame bodies  19 , when the portions of the frame bodies  19  between the portions  3   a  and the other portions  3   b  are elastically deformed and extend and contract so that they bend left and right, the damping force generating means  44  extend and contract more largely than the extension and contraction of the portions of the frame bodies  19 , whereby the “action and effects” are even more reliably achieved. 
   The fasteners  36  that support the internal combustion engine  34  of the drive device  33  at the frame bodies  19  and the fasteners  46  of the couplers  42  are mutually shared, whereby the configuration is simplified. Also, the fasteners  46  of the couplers  43  are disposed on an axial center of the pivot support shaft  9 . 
   As shown by the single-dot chain line in  FIG. 1 , the portions  3   a  may serve as the front end portions of the frame bodies  19  near the head pipe  18  and the other portions  3   b  may serve as the extension end portions of the frame bodies  19 , so that damping force generating means  44 (A) may be disposed so as to bridge the frame bodies  19 . 
   Here, the front end portions of the frame bodies  19  are portions at which a large impact force is inputted from the outside via the front fork  6  from the front wheel  8 . The extension end portions of the frame bodies  19  are portions at which a large impact force is inputted from the rear arm  10  and the drive device  33 , and the portions of the frame bodies  19  between the portions  3   a  and the other portions  3   b  include the curved portions. 
   For this reason, the portions of the frame bodies  19  between the portions  3   a  and the other portions  3   b  tend to be elastically deformed by the impact force, so that they largely bend up and down and left and right. In other words, the portions  3   a  and the other portions  3   b  tend to be elastically deformed so that they move towards and away from each other. However, the damping force generating means  44 (A) disposed so as to bridge the frame bodies  19  extend and contract with the elastic deformation, whereby the “action and effects” are more reliably achieved. 
   Also, as shown by the single-dot chain line in  FIGS. 1 and 2 , damping force generating means  44 (B) may be disposed so as to extend in the width direction of the vehicle  1 , the damping force generating means  44 (B) may be disposed so as to bridge the front portions of the left and right frame bodies  19 ,  19  (intermediate portions in the longitudinal direction of the main frames  22 ) of the body frame  3 , and end portions of the damping force generating means  44 (B) may be coupled by the couplers  42  and  43  to the portion  3   a  of one frame body  19  of the left and right frame bodies  19 ,  19  and to the other portion  3   b  of the other frame body  19 . 
   Here, the left and right frame bodies  19 ,  19  have curved shapes that are outwardly convex when the vehicle body  2  is seen in plan view, their cross sections are long shapes, and they are respectively and separately elastically deformed by the impact force, so that they easily bend in the width direction of the vehicle body  2 . Additionally, when the left and right frame bodies  19 ,  19  are elastically deformed so that they largely move towards and away from each other, the portions  3   a  and the other portions  3   b  largely move towards and away from each other in accompaniment with this elastic deformation, whereby the damping force generating means  44 (B) disposed so as to bridge the left and right frame bodies  19 ,  19  extend and contract, whereby the “action and effects” are effectively achieved. 
   It should be noted that, as shown by the single-dot chain line in  FIG. 1 , damping force generating means  44 (C) extending in the width direction of the vehicle  1  may also be disposed so as to bridge the curved portions of the left and right frame bodies  19 . 
   Although the above depends on the illustrated example, the vehicle  1  may be a three-wheeled motor vehicle or a four-wheeled motor vehicle as long as it is a saddle type. Also, the damping force generating means  44  may be disposed in internal spaces of the frame bodies  19  whose cross sections are of a box-like shape, and may be disposed to bridge the portions  3   a  and the other portions  3   b  of inner surface sides of the frame bodies  19 . Also, these portions  3   a  and other portions  3   b  may also be portions of upper and lower surfaces, regardless of whether they are disposed at the outer or inner surface sides of the frame bodies  19 . Also, the end portion (front end portion) of the damping force generating means  44  may be coupled to the front portion of one of the left and right frame bodies  19 ,  19  and the other end portion (rear end portion) of the damping force generating means  44  may be coupled to the rear portion of the other frame body  19 . 
   Also, the frame bodies  19  may be a single body extending rearward from the head pipe  18  and may be configured by a simple circular pipe. In this case, the damping force generating means  44  may also be made singular. 
   Also, an end portion of the damping force generating means  44  may be coupled to the head pipe  18  and the other end portion may be coupled to one of the cross members  20  and  21 . In this case, the head pipe  18  and the cross member  20  function as a partial configuration of the couplers  42  and  43 . 
   Also, the damping force generating means  44  may be means where the piston frictionally slides with respect to the cylinder tube  50  without using a fluid. Also, the damping force generating means  44  may include a rubber-made elastic body that is vulcanized and adhered to the cylinder tube  50  and the piston rod  51  and in which sheering stress is generated on the basis of the impact force, with the cylinder tube  50  and the piston rod  51  being mutually joined together by the elastic body, without using a fluid and a piston. 
   Moreover, the damping force generating means  44  may be disposed with a damper body, in which a fluid is used in a rotary format supported at the portions  3   a  of the frame bodies  19 , and an interlocking rod that couples the damper body and the other portions  3   b  of the frame bodies  19 . 
     FIGS. 5 to 7 , which will be described below, show a second embodiment. In this embodiment, many points are shared in common with the first embodiment in terms of configuration, action and effects. Thus, with respect to these points shared in common, common reference numerals will be given to the drawings, overlapping description thereof will be omitted, and description will be given mainly in regard to points of difference. Also, in light of the aspects, action and effects of the invention, the configurations of portions in these embodiments may be variously combined. 
   (Second Embodiment) 
     FIGS. 5 to 7  show the second embodiment. 
   According to this, the damper  14  is disposed as a left and right pair. The body frame  3  is disposed with brackets  53  that are respectively disposed so as to protrude upward from the joint portions at which the rear end portions of the main frames  22  and the upper end portion of the rear arm brackets  23  are joined. Intermediate portions of swinging arms  54  that respectively extend in the front-rear direction with respect to protruding end portions of the left and right brackets  53  are pivotally supported. Upper end portions of the dampers  14  are pivotally supported at end portions (rear end portions) of the swinging arms  54 , and lower end portions of the dampers  14  are pivotally supported at the rear arms  10 . Also, turn buckle-format regulation bars  55 , which are respectively disposed forward of the dampers  14 , extend along the dampers  14 , and whose respective lengths are adjustable in the axial direction, are disposed. Additionally, upper end portions of the regulation bars  55  are pivotally supported at other end portions (front end portions) of the swinging arms  54 , and lower end portions of the regulation bars  55  are pivotally supported at the rear arm  10 . By adjusting the lengths of the regulation bars  55 , damper characteristics of the dampers  14  are possible. 
   A pair of left and right damper force generating means  44 (D), which extend in the front-rear direction, are disposed so as to bridge the portions  3   a  (front portions) and the other portions  3   b  (rear portions) of the outer surface sides of the frame bodies  19  in the body frame  3 , and are respectively coupled by the couplers  43 ,  43  to the portions  3   a  and the portions  3   b , is disposed. 
   The damping force generating means  44 (D) are positioned near upper portions of linear portions  19   a  of the main frames  22  of the frame bodies  19 . For this reason, even if the damping force generating means  44 (D) are disposed, the width dimension of the vehicle body  2  is prevented from becoming larger, which is particularly beneficial with respect to the saddle-type vehicle  1  for which a compact width dimension of the vehicle body  2  is demanded. 
   Also, damping force generating means  44 (E), which are disposed so as to bridge the frame bodies  19  and the seat bracket  26  via the upper cross member  20  and are respectively coupled by the couplers  42  and  43  to the frame bodies  19  and the seat bracket  26 , are disposed. 
   Here, the seat bracket  26  supporting the seat  28  projects from the frame bodies  19  and is cantilever-supported. When an impact force is applied to the body frame  3 , the seat bracket  26  is elastically deformed more than other portions and tends to be largely relatively displaced with respect to the frame bodies  19 . However, in this case the damping force generating means  44 (E) extend and contract, whereby the “action and effects” are more reliably achieved. 
   Also, a pair of left and right damping force generating means  44 (F),  44 (F), which are disposed so as to bridge the frame bodies  10  and the internal combustion engine  34  and are respectively coupled by the couplers  42  and  43  to the frame bodies  19  and the internal combustion engine  34 , is disposed. 
   Here, there is a large difference—particularly with respect to weight, specific gravity and rigidity—between the internal combustion engine  34  and the frame bodies  19  of the body frame  3 . Thus, when an impact force is applied to the body frame  3 , the frame bodies  19  tend to be largely elastically deformed in comparison to the internal combustion engine  34  and more largely relatively displaced with respect to the internal combustion engine  34 . However, in this case, the damping force generating means  44 (F) extend and contract, whereby the “action and effects” are more reliably achieved. 
   Although the above depends on the illustrated example, it is not necessary to dispose all of the damping force generating means  44 (D–F) at the same time. 
   Effects according to the invention are as follows. 
   According to the present invention, a body frame damping structure in a saddle-type vehicle includes a front fork steerably supported at a front end portion of a body frame; a front wheel supported at lower end portions of the front fork; a rear arm pivotally supported at a rear portion of the body frame by a pivot support shaft so as to be swingable up and down; and a rear wheel supported at a swinging end of the rear arm. 
   The damping force generating means are disposed so as to bridge portions of the body frame with other portions of the body frame, with the damping force generating means being respectively coupled to the portions and the other portions. 
   For this reason, when the body frame is elastically deformed by the impact force applied to the body frame at the time the vehicle is traveling, the impact force is damped by the damping force generating means bridging the body frame, and the body frame is deterred from being largely elastically deformed by a reaction force generated in the damping force generating means. 
   Thus, for example, when a large impact force is applied to the body frame from a traveling road surface at the time of high-speed cornering in a race, the body frame tries to largely elastically deform in the saddle-type vehicle for which compactness and lightness are demanded, but this elastic deformation is prevented by the working of the damping force generating means and a sense of being one with the vehicle is ensured for the rider. In other words, as described above, even when the impact force on the body frame is large, steering stability is satisfactorily maintained. 
   The body frame includes a head pipe, which configures the front end portion of the body frame and supports the front fork, and a frame body, which extends rearward and downward from the head pipe and pivotally supports the rear arm at extension portions of the frame body, the frame body being disposed with linear portions that extend substantially straightly. 
   The damping force generating means are disposed at outward vicinities of the linear portions so as to extend along the linear portions. 
   For this reason, as described above, even if the damping force generating means are disposed so that steering stability is satisfactorily maintained, the damping force generating means are prevented from projecting largely outward from the frame bodies of the body frame. Since these are disposed compactly, the vehicle body is prevented from becoming large, and the damping force generating means are prevented from becoming an obstacle to a rider, which is particularly beneficial to a saddle-type vehicle. 
   Moreover, because the damping force generating means are disposed so as to bridge outer portions of the frame bodies, firstly, they can be disposed regardless of the cross-sectional shape of the frame bodies, the degree of freedom of their disposal is improved, and it also becomes possible to dispose them later with respect to existing body frames. Also, secondly, when the damping force generating means are disposed, constraints attendant to the cross-sectional shape of the body frame can be avoided and molding of the body frame can be easily achieved. 
   The frame body includes a pair of left and right frame bodies and the damping force generating means is disposed so as to extend in a width direction of the vehicle and bridge the left and right frame bodies, with the damping force generating means being coupled to the frame bodies. 
   Here, the left and right frame bodies are respectively and separately elastically deformed by the impact force so that they bend and tend to largely move towards and away from each other. However, in this case, the damping force generating means disposed so as to bridge the left and right frame bodies extends and contracts, whereby the action and effects of the present invention is reliably achieved. 
   A further embodiment of the present invention is a body frame damping structure in a saddle-type vehicle includings a front fork steerably supported at a front end portion of a body frame; a front wheel supported at lower end portions of the front fork; a rear arm pivotally supported at a rear portion of the body frame by a pivot support shaft so as to be swingable up and down; and a rear wheel supported at a swinging end of the rear arm. The body frame includes a head pipe, which configures the front end portion of the body frame and supports the front fork, a frame body, which extends rearward and downward from the head pipe and pivotally supports the rear arm at extension portions of the frame body, and a seat bracket, which projects rearward from the frame body and supports a seat. 
   The damping force generating means are disposed so as to bridge the frame body and the seat bracket, with the damping force generating means being respectively coupled to the frame body and the seat bracket. 
   Here, the seat bracket supporting the seat projects from the frame bodies and is cantilever-supported. When the impact force is applied to the body frame, the seat bracket is elastically deformed more than other portions and tends to be largely relatively displaced with respect to the frame bodies. However, in this case, the damping force generating means extends and contracts. 
   Another embodiment of the present invention is a body frame damping structure in a saddle-type vehicle including a front fork steerably supported at a front end portion of a body frame; a front wheel supported at lower end portions of the front fork; a rear arm pivotally supported at a rear portion of the body frame by a pivot support shaft so as to be swingable up and down; and a rear wheel supported at a swinging end of the rear arm. The body frame including a head pipe, which configures the front end portion of the body frame and supports the front fork, a frame body, which extends rearward and downward from the head pipe and pivotally supports the rear arm at extension portions of the frame body, and an internal combustion engine, which is supported at the frame body and is interlocked and coupled with the rear wheel. 
   The damping force generating means are disposed so as to bridge the frame body and the internal combustion engine, with the damping force generating means being respectively coupled to the frame body and the internal combustion engine. 
   Here, there is a large difference—particularly with respect to weight, specific gravity and rigidity—between the internal combustion engine and the frame bodies of the body frame. Thus, when an impact force is applied to the body frame, the frame bodies tend to be largely elastically deformed in comparison to the internal combustion engine and more largely relatively displaced with respect to the internal combustion engine. However, in this case, the damping force generating means extend and contract. 
   The damping force generating means damp an impact force applied in one direction to the damping force generating means and an impact force applied in a direction opposite to the one direction. 
   For this reason, the damping force generating means damp impact forces in both of one direction with respect to the damping force generating means and the direction opposite thereto, and more effectively suppress elastic deformation of the body frame.