JP4558604B2 - Low floor vehicle - Google Patents

Description

  The present invention relates to a low floor type vehicle such as a scooter type motorcycle.

Conventionally, the low floor type vehicle has a low floor portion which is a footrest portion for the occupant between a front wheel steering handle and an occupant seat, and the vehicle is located in the vicinity of the low floor portion. A driving engine is supported by a vehicle body frame, and a swing arm that pivotally supports a rear wheel is pivotally supported at the rear part of the engine (see, for example, Patent Document 1).
JP-A-11-301559

By the way, in recent low floor type vehicles, the displacement of the engine tends to increase, and the engine and the body frame tend to increase in size and weight. Along with such a trend, there is a demand for high vehicle body rigidity. On the other hand, it is necessary to fully consider the torsion of the entire vehicle body as the engine driving force increases. In other words, the vehicle body is moderately twisted to ensure good turning performance, while the left-right shift between the traveling direction of the rear wheel and the grounding portion of the front wheel due to the torsion of the vehicle body is suppressed, and a sense of unity between the vehicle body front and rear can be obtained. Such a configuration is desired.
Further, in order to meet the above demand, in general, the body frame shape and the rubber mount of the engine are often used to adjust the rigidity and torsion of the vehicle body. However, in such a configuration, the adjustment is difficult and the weight is adjusted. May increase costs.
The present invention has been made in view of the above circumstances, and provides a low-floor type vehicle capable of suppressing a lateral shift between a traveling direction of a rear wheel and a grounding portion of a front wheel due to a twist of the vehicle body, and suppressing a vehicle body weight and cost. To do.

As a means for solving the above problems, the invention described in claim 1 is supported by a vehicle body frame (for example, the vehicle body frame 6 of the embodiment) in the vicinity of the low floor portion (for example, the low floor portion 2 of the embodiment) which is a footrest portion. The engine (for example, the engine 15 or 115 of the embodiment) is disposed, and a swing arm (for example, the swing arm 25 of the embodiment) for supporting the rear wheel (for example, the rear wheel 9 of the embodiment) is disposed at the rear of the engine. An upper down pipe (for example, the upper down pipe 58 of the embodiment) that is pivotally supported so that the vehicle body frame branches left and right from the upper part of the head pipe (for example, the head pipe 7 of the embodiment) and extends obliquely downward and rearward. And a lower down pipe (for example, the lower down pipe 59 in the embodiment) which branches from the lower part of the head pipe to the left and right and extends obliquely downward and rearward at a slightly steep slope than the upper down pipe. That a down frame (down frames 11 of the example embodiment), the main frame of the main frame (e.g., embodiments comprising the above said engine from a lower portion of the down frame from the main pipe extending rearward (e.g. main pipe 65 in the embodiment) 12), wherein the seat frame 13) becomes and a low floor type vehicle seat frame (e.g. example extending obliquely upward and rearward from the rear portion of the main frame (e.g., the motorcycle 1 and 101 in the embodiment),
The main pipe has a front end joined to the lower part of the lower down pipe from the rear , and a lower end of the upper down pipe is joined to the front from above, and at least swings from the upper front of the engine. The arm shaft support portion (for example, the swing arm shaft support portion 18a of the embodiment) extends upward and the intermediate portion is curved and provided so as to protrude upward in a vehicle side view ,
The seat frame includes a left and right seat pipe (for example, the seat pipe 70 of the embodiment) that extends obliquely upward and rearward from the vicinity of the curved portion of the left and right main pipes and has a bent portion at an intermediate portion, and a rear end portion of the left and right main pipes. Left and right rear pipes extending obliquely upward and rearward (for example, the rear pipe 71 of the embodiment), a rear side plate (for example, the rear side plate 72 of the embodiment) for connecting the rear portion of the seat pipe and the rear portion of the rear pipe, and the rear end portion of the main pipe A rear gusset pipe (for example, the rear gusset pipe 73 of the embodiment) that extends at a slant from the upper side to the rear and is coupled to the bent portion of the seat pipe,
The engine mount portion of the end portion to the rear portion of the main pipe (for example, an engine mount portion C2 of the last portion in the embodiment) provided, an engine mount portion of the lower end of the lower down pipe is foremost (e.g. front of the Example Engine mount part C1),
The foremost engine mount portion is a line (for example, a straight line in the embodiment) that connects the rearmost engine mount portion and a ground portion (for example, the front wheel ground portion FT) of the front wheel (for example, the front wheel 3 in the embodiment) in a side view of the vehicle. L) located on,
A third engine mount portion (for example, the third engine of the embodiment) that supports the upper portion of the engine in the vicinity of a joint portion of the front portion of the main pipe with the upper down pipe in a side view of the vehicle. Mount portion C3),
The swing arm connects the front inner sides of left and right arm members (for example, the arm members 27 and 28 of the embodiment) with a cross member (for example, the cross member 29 of the embodiment), and a cushion connecting portion ( For example, the cushion connecting portion 29a) of the embodiment is erected upward, and the longitudinal direction is along the front-rear direction between the cushion connecting portion and the longitudinal middle portion of the main frame, and the line is seen in a vehicle side view. And the cushion unit (for example, the cushion unit 30 of an Example) is arrange | positioned so that the last engine mount part may be straddled back and forth .

  The invention described in claim 2 is characterized in that the crankshaft portion of the engine (for example, the crankshaft portion CJ of the embodiment) is positioned on the line in a side view of the vehicle.

  According to a third aspect of the present invention, the exhaust muffler of the engine (for example, the exhaust of the embodiment) is disposed on the line in a side view of the vehicle and above the grounding portion of the rear wheel (for example, the rear wheel grounding portion RT of the embodiment). The support part (for example, the exhaust muffler support part C4 of the embodiment) of the muffler 44A) is located.

The invention described in claim 4 is characterized in that the lower down pipe is provided so as to be substantially orthogonal to the line in a side view of the vehicle.

According to a fifth aspect of the invention, the engine (for example, the engine 115 of the embodiment) is a V-type engine having front and rear cylinders (for example, the front and rear cylinders 117f and 117r of the embodiment), and the third engine mount portion is , It is arranged between the front and rear cylinders.

According to a sixth aspect of the present invention, the vehicle body frame does not have a frame member that extends downward from the down frame to the engine, and has a frame member that extends downward from the main frame on the rear side of the engine. It is characterized by not.

According to the first aspect of the present invention, the vehicle body rear portion including the rear wheel suspended via the engine and the swing arm, the vehicle body frame, and the front wheel steering system pivotally supported by the vehicle when the vehicle is turning. If the main frame extends from above the front of the engine to above the swing arm shaft support to ensure its rigidity, the torsion takes a long distance between the engine mounts. It can be generated around the line connecting the foremost engine mount and the last engine mount, and if the grounding part of the front wheel is positioned on the line, the rear wheel advances relative to the grounding part. It becomes possible to suppress the deviation of the direction. In other words, the vehicle body can be twisted moderately during turning, etc., to improve the turning performance of the vehicle, and the front-wheel front and rear can be prevented from shifting from the traveling direction of the rear wheel due to the torsion of the vehicle body. This makes it possible to enhance the sense of unity, make the occupant feel the rigidity of the vehicle body, and freely set the response when the vehicle moves quickly.
In addition, the engine is supported at a position where the body rigidity is relatively high and away from the line, and even when the engine weight increases as the displacement increases, the twist amount around the line can be easily adjusted. can do.
Furthermore, the rigidity of the down frame itself is increased and the lower part thereof is coupled to the engine, so that the rigidity of the front part of the vehicle body can be increased efficiently.

  According to the second aspect of the present invention, the target torsional characteristics can be obtained more efficiently by bringing the torsion line of the vehicle body close to the rotation center of the crankshaft having a large gyro effect.

  According to the third aspect of the present invention, the torsion of the vehicle body is likely to occur around the line that supports the engine including its exhaust system, and further suppresses the deviation between the front wheel ground contact portion and the rear wheel traveling direction. it can.

  According to the fourth aspect of the present invention, the length of the down frame is suppressed, the amount of deflection thereof is reduced, and the deviation between the front wheel ground contact portion and the rear wheel traveling direction can be further suppressed.

According to the fifth aspect of the present invention, it is possible to efficiently ensure engine support rigidity when a high-performance and narrow V-type engine is mounted.

According to the invention described in claim 6 , by not having a frame member below the engine,
The engine can be lowered and the center of gravity of the vehicle can be set lower. Further, the weight and cost can be reduced by eliminating the frame members extending downward from the down frame and the main frame.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the directions such as front, rear, left and right are the same as those in the vehicle unless otherwise specified. In the figure, the arrow FR indicates the front of the vehicle, the arrow LH indicates the left side of the vehicle, and the arrow UP indicates the upper side of the vehicle.

  A motorcycle 1 shown in FIG. 1 is a scooter type vehicle (low floor type vehicle) having a low floor portion 2 that is a footrest portion for an occupant, and its front wheels 3 are pivotally supported by left and right front forks 4. The front fork 4 is pivotally supported by a head pipe 7 at the upper front end of the vehicle body frame 6 via a handle stem 5, and a steering handle 8 is attached to the upper portion of the handle stem 5. Here, a grounding portion (front wheel grounding portion) of the front wheel 3 is indicated by a symbol FT in the drawing.

  The vehicle body frame 6 is formed by integrally joining a plurality of types of steel materials by welding or the like, and includes a down frame 11 extending obliquely downward and rearward from the head pipe 7 and a lower floor portion 2 extending rearward from the lower portion of the down frame 11. Mainly, a main frame 12 that passes above the inner engine 15 and a seat frame 13 that extends obliquely upward and rearward from the rear portion of the main frame 12 are mainly used.

  The engine 15 which is a prime mover of the motorcycle 1 is, for example, a water-cooled four-stroke single-cylinder engine, which is arranged with a crankshaft parallel to the left-right direction, and a cylinder 17 is erected substantially forward from the front end of the crankcase 16. Have a configuration. Here, a crankshaft portion (center of rotation of the crankshaft) in a side view of the vehicle is indicated by a symbol CJ. A transmission case 18 is connected to the rear of the crankcase 16, and a pivot shaft 26 is provided at the rear end of the transmission case 18 so that the front end of a swing arm 25 that pivotally supports the rear wheel 9 extends in the left-right direction. And is pivotally supported so as to swing up and down.

  The swing arm 25 is formed by connecting the front inner sides of the left and right arm members 27 and 28 with a cross member 29, and the rear wheel 9 is pivotally supported at the rear end portion thereof. Here, a grounding portion (rear wheel grounding portion) of the rear wheel 9 is indicated by a symbol RT in the drawing. A cushion connecting portion 29a is erected on the upper part of the cross member 29, and a cushioning coil spring and a damper are integrally provided between the cushion connecting portion 29a and the longitudinal intermediate portion of the main frame 12 in an integrated manner. 30 is arranged so that its longitudinal direction (stroke direction) is generally along the front-rear direction.

  In the transmission case 18, a drive pulley 21 coaxially arranged with the crankshaft, a driven pulley 22 coaxially arranged with the transmission shaft behind the crankshaft, and an endless drive belt 23 wound around these pulleys. And the continuously variable transmission 20 mainly. The rotational power of the crankshaft is steplessly changed through the continuously variable transmission 20, and after the centrifugal clutch and the final reduction mechanism (both not shown), the drive on the left side of the rear end of the transmission case 18 is driven. It is output to the sprocket 34.

  An endless drive chain 36 is wound around the drive sprocket 34 and the driven sprocket 35 on the left side of the rear wheel 9, and power can be transmitted between the engine 15 and the rear wheel 9 via the drive chain 36. The The drive sprocket 34 is arranged coaxially with the pivot shaft 26 of the swing arm 25.

  A radiator 39 is disposed in front of the cylinder head 17a, an air cleaner case 40 is disposed above the radiator 39, and an intake pipe 42 extending obliquely downward and rearward from a throttle body 41 connected to a rear portion of the air cleaner case 40 is provided in the cylinder. It is connected to the intake port at the top of the head 17a. An exhaust pipe 43 is connected to the exhaust port below the cylinder head 17a. The exhaust pipe 43 curves below the cylinder head 17a and passes below the crankcase 16 rearward. It rises diagonally upward and rearward and is connected to a silencer 44 disposed on the rear right side of the vehicle body. Hereinafter, the exhaust pipe 43 and the silencer 44 may be collectively referred to as an exhaust muffler 44A.

  The vehicle body frame 6 and the engine 15 are covered with a vehicle body cover 46 made of synthetic resin. The body cover 46 covers a front cowl 47 that covers a range extending from the front of the head pipe 7 to both sides, an inner cover 48 that covers the rear of the head pipe 7, and covers both sides of the lower portion of the engine 15. An under cowl 49, a floor cover 50 that continues below the inner cover 48 and covers the upper portion of the engine 15, and a rear side cover 51 that is provided on both sides below the seat 53 and covers both sides of the rear part of the vehicle body are mainly used.

  The seat frame 13 and the rear side cover 51 support a seat 53 in which a front seating portion for a driver and a rear seating portion for a rear passenger are integrally provided. The seat 53 pivots up and down around the hinge shaft 54 at the front end thereof, thereby opening and closing the article storage box 55 below the front seating portion and allowing access to the fuel tank 56 below the rear seating portion. And The article storage box 55 has a front portion positioned above the rear portion of the crankcase 16, a rear portion positioned above the front portion of the swing arm 25, and a bottom portion that is branched so as to straddle the cushion unit 30. The rear side of the bottom portion is provided so as to incline rearwardly so as to ensure a gap when the swing arm 25 is swung.

  The down frame 11 in the vehicle body frame 6 is branched from the upper part of the head pipe 7 to the left and right and extends obliquely downward and rearwardly, and the upper down pipe 58 is branched from the lower part of the head pipe 7 to the left and right. A lower down pipe (lower frame member) 59 extending obliquely downward and rearward with a slightly steeper slope than 58 is mainly used.

  Between the lower part of the head pipe 7 and the upper middle part of the upper down pipe 58, a gusset pipe 60 arranged substantially horizontally is provided, and the upper end of the lower down pipe 59 is passed through the gusset pipe 60. The part is joined to the lower part of the head pipe 7. In the figure, reference numeral 61 denotes a gusset plate straddling the upper part of the lower down pipe 59, the front part of the gusset pipe 60, and the lower part of the head pipe 7.

  A front engine hanger bracket 62 that also extends obliquely downward and rearward is connected below the lower down pipe 59, and a front lower engine hanger 63 is fastened to a lower end portion of the front engine hanger bracket 62 so that the front lower engine The rear end portion of the hanger 63 is fastened to and supports the lower side of the front portion of the crankcase 16 of the engine 15. Here, the axial center (frontmost engine mount portion) of the bolt along the vehicle width direction that fastens the front lower engine hanger 63 and the engine 15 is denoted by reference numeral C1 in the figure.

  The main frame 12 mainly includes a pair of left and right main pipes 65 corresponding to the left and right upper down pipes 58 and the lower down pipe 59. The main pipe 65 is disposed substantially horizontally at the center of the vehicle body, and is provided with a slight curve so that an intermediate portion thereof is convex upward in a side view of the vehicle. The front end portion of the main pipe 65 is joined to the lower portion of the lower down pipe 59 from the rear, and the lower end portion of the upper down pipe 58 is joined to the front portion from above.

  The main pipe 65 (main frame 12) extends from above the cylinder head 17a of the engine 15 to above the swing arm shaft support 18a at the rear end of the transmission case 18, and at the rear end of the main pipe 65, A rear engine hanger bracket 66 extending rearward is provided so as to continue to this. A rear upper engine hanger 67 projecting downward is provided at the lower portion of the rear engine hanger bracket 66, and a lower end portion of the rear upper engine hanger 67 is connected to and supports the rear upper side of the transmission case 18. . Here, the axial center (the last engine mount portion) of the bolt along the vehicle width direction that fastens the rear upper engine hanger 67 and the engine 15 is indicated by a symbol C2.

  Further, a front upper engine hanger 68 is fastened to a front portion of the main pipe 65 and a joint portion with the upper down pipe 58, and a lower end portion of the front upper engine hanger 68 is connected to the crankcase 16 of the engine 15. It is fastened to the front upper side of the support to support it. Here, the axial center (third engine mount portion) of the bolt along the vehicle width direction that fastens the front upper engine hanger 68 and the engine 15 is indicated by a symbol C3 in the figure. The engine 15 is suspended from the vehicle body frame 6 by using the third engine mount portion C3 and the three portions of the foremost engine mount portion C1 and the rearmost engine mount portion C2.

The seat frame 13 mainly includes left and right seat pipes 70 extending obliquely upward and rearward from the vicinity of the curved portion of the left and right main pipes 65 and left and right rear pipes 71 extending obliquely upward and rearward from the rear ends of the left and right main pipes 65. The seat pipe 70 is bent and provided so that an intermediate portion thereof protrudes obliquely upward and upward in a side view of the vehicle, and the left and right end portions thereof are provided integrally with each other. The rear part of the seat pipe 70 and the rear part of the rear pipe 71 are coupled via a rear side plate 72. Further, the upper end portion of the rear gusset pipe 73 extending from the rear end portion of the main pipe 65 with a steep slope obliquely upward and rearward is joined to the bent portion of the seat pipe 70 from below.

  Here, in this embodiment, the body frame 6 is a so-called diamond type frame in which the frame member below the engine 15 is eliminated, and the engine 15 also serves as a reinforcing member for the body frame 6. Accordingly, the position of the engine 15 can be lowered to lower the center of gravity, and the weight and cost of the vehicle body frame 6 can be suppressed by reducing the number of frame members. The body frame 6 also eliminates a frame member (so-called pivot plate) that extends downward from the main frame 12 on the rear side of the engine 15, further reducing the weight and cost.

  The silencer 44 on the right side of the rear part of the vehicle body has, for example, a cylindrical appearance along the rearward rising axis, and is disposed at a position below the rear pipe 71 of the seat frame 13 in a side view of the vehicle. A support bracket 44b that protrudes upward is provided at an intermediate portion in the longitudinal direction of the silencer 44, and the support bracket 44b is fastened to a muffler hanger 74 that protrudes downward from the rear portion of the rear pipe 71. The rear portion of the exhaust muffler 44A is supported by the seat frame 13. Here, the axial center of the bolt (supporting portion of the exhaust muffler 44A) along the vehicle width direction for fastening the seat frame 13 and the exhaust muffler 44A is indicated by a symbol C4 in the drawing. The support portion (exhaust muffler support portion) C4 is located on a vertical line that generally passes through the rear wheel ground contact portion RT.

  Here, in the vehicle side view of the motorcycle 1, the front wheel grounding portion FT, the frontmost engine mount portion C1 in the front lower engine hanger 63, and the rearmost engine mount portion C2 in the rear upper engine hanger 67 are: It arrange | positions so that it may be located on the straight line L which goes up back.

  Further, the exhaust muffler support portion C4 in the muffler hanger 74 and the crankshaft portion CJ in the engine 15 are also positioned on an extension of the straight line L in the vehicle side view. With respect to such a straight line L, the lower down pipe 59 in the down frame 11 is provided so as to be substantially orthogonal in a vehicle side view.

  FIG. 2 is a diagram schematically showing a state in which the rear wheel grounding portion RT is shifted to the left and right with respect to the front wheel grounding portion FT due to the twisting of the vehicle body that occurs during turning of the motorcycle 1 and the like. In addition, for example, when the motorcycle 1 tries to turn or a torsional force is applied between the front part of the vehicle body and the rear part of the vehicle body due to a disturbance, the torsion occurs around the straight line L. 9 in the direction of travel (indicated by the arrow S in FIG. 2).

  The characteristics of the torsion of the vehicle body as described above can be changed mainly by adjusting the rigidity of the engine mounts C1, C2, and C3 in the vehicle body frame 6. That is, by rearranging the engine mount portions C1, C2, C3 or changing the rigidity of the engine hangers 63, 67, 68, the rear wheel suspension via the engine 15 and the swing arm 25 supported by the engine 15 is supported. To change the torsion degree between the rear part of the vehicle body including the system and the front part of the vehicle body including the front wheel steering system via the vehicle body frame 6 and the front fork 4 supported by the vehicle body. it can.

  Here, the distance between the foremost engine mount C1 that supports the lower front side of the crankcase 16 and the rearmost engine mount C2 that supports the upper rear side of the crankcase 16 is determined by the respective engine mounts. Since the bending rigidity between the engine mounts is longer than the distance between C1, C2 and the third engine mount C3, the torsion of the vehicle body causes the foremost and rearmost engine mount C1. , C 2, that is, the line L is likely to be generated.

  At this time, the amount of twist of the vehicle body can be adjusted relatively easily by adjusting the rigidity of the third engine mount portion C3 that is separated by a predetermined amount above the straight line L in a side view of the vehicle. Also, the lower down pipe 59 connected to the third engine mount C3 is arranged so as to be substantially orthogonal to the straight line L, so that the length of the lower down pipe 59 is suppressed and the amount of deflection thereof is reduced. Is likely to occur around the straight line L.

  As a result, the traveling direction of the rear wheel 9 is such that the rear wheel 9 swings about the straight line L passing through the front wheel grounding part FT, so that the vehicle body is twisted around the straight line L and the rear wheel grounding part RT Even when the left and right are shifted, the traveling direction of the rear wheel 9 is directed to the front wheel ground contact portion FT. That is, by adopting the configuration of the present invention, it becomes easy to adjust the rigidity of the vehicle body so that the front wheel ground contact portion FT does not deviate from the traveling direction of the rear wheel 9 even if the vehicle body is twisted. It becomes possible to raise.

  As described above, in the motorcycle 1 in the above-described embodiment, the engine 15 supported by the vehicle body frame 6 is disposed in the vicinity of the low floor portion 2 that is a footrest portion, and the rear wheel 9 is disposed at the rear portion of the engine 15. The vehicle body frame 6 extends downward from the head pipe 7 obliquely downward and rearward, and extends downward from the lower frame 11 above the engine 15. A low-floor type vehicle having a main frame 12 and a seat frame 13 extending obliquely upward and rearward from the rear portion of the main frame 12, wherein the main frame 12 is a swing arm shaft support portion from above the front portion of the engine 15. 18a, and a rearmost engine mount C2 is provided at the rear of the main frame 12, while the down frame 11 has a frontmost portion. An engine mount portion C1 provided, outermost front of the engine mount portion C1 is what located on the straight line L connecting the ground portion FT of the engine mount portion C2 and the front wheel 3 of the last portion in the vehicle side view.

  According to this configuration, when the motorcycle 1 is turning, for example, the rear part of the vehicle body including the rear wheel 9 suspended via the engine 15 and the swing arm 25, the vehicle body frame 6 and the front wheel steering pivotally supported by the vehicle body frame 6 are provided. When twisting occurs between the front part of the vehicle body including the system and the main frame 12 is extended from above the front part of the engine 15 to above the swing arm shaft support part 18a to ensure the rigidity thereof, the twisting is caused by the engine. A straight line L connecting the frontmost engine mount part C1 and the rearmost engine mount part C2 having a long distance between the mounts can be formed at the center, and the grounding part FT of the front wheel 3 can be formed on the straight line L. If it is positioned, it is possible to suppress a deviation in the traveling direction of the rear wheel 9 with respect to the ground contact portion FT. In other words, the vehicle body is moderately twisted during turning and the like, thereby improving the turning performance of the vehicle and suppressing the ground contact portion FT of the front wheel 3 from being displaced from the traveling direction of the rear wheel 9 due to the twist of the vehicle body. Enhances the sense of unity between the front and rear of the vehicle, makes the occupant feel the rigidity of the vehicle, and allows the user to freely set the response when the vehicle moves quickly.

  Further, in the motorcycle 1, the crankshaft portion CJ of the engine 15 is positioned on the straight line L in a side view of the vehicle so that the torsion line of the vehicle body and the rotation center of the crankshaft having a high gyro effect are brought close to each other. As a result, the desired torsional characteristics can be achieved without waste.

  Furthermore, in the motorcycle 1, the support portion C4 of the exhaust muffler 44A of the engine 15 is positioned on the straight line L and above the grounding portion RT of the rear wheel 9 in a side view of the vehicle, whereby the vehicle body is twisted. It becomes easy to produce centering on the straight line L which supports the engine 15 including the exhaust system, and the shift | offset | difference with front wheel grounding part FT and a rear-wheel advancing direction can further be suppressed.

  Furthermore, in the motorcycle 1, the down frame 11 is provided so as to be substantially orthogonal to the straight line L in a side view of the vehicle, so that the length of the down frame 11 is suppressed and the amount of deflection is reduced. The deviation between the ground contact portion FT and the rear wheel traveling direction can be further suppressed.

  Moreover, in the motorcycle 1, the third engine mount C3 that supports the upper portion of the engine 15 is provided above the straight line L in a side view of the vehicle, so that the vehicle body has relatively high rigidity and is separated from the straight line L. Thus, the engine 15 is supported even at this position, and the amount of twist about the straight line L can be easily adjusted even when the engine weight increases as the displacement increases.

  Here, in the motorcycle 1, the down frame 11 has an upper down pipe 58 and a lower down pipe 59 that extend so as to be lined up and down, and the third engine mount portion C3 is connected to the upper down pipe 59. By being provided in the vicinity of the joint portion with the main frame 12, the rigidity of the down frame 11 itself is increased and the lower portion thereof is coupled to the engine 15, so that the front portion of the vehicle body can be efficiently and highly rigid.

  Further, in the motorcycle 1, the body frame 6 does not have a frame member that extends from the down frame 11 to the lower side of the engine 15, and has a frame member that extends downward from the main frame 12 on the rear side of the engine 15. By not doing so, the engine 15 can be lowered downward, and the position of the center of gravity of the vehicle can be set low. Moreover, weight and cost can be reduced by eliminating each frame member extending downward from the down frame 11 and the main frame 12.

Next, a second embodiment of the present invention will be described.
This second embodiment differs from the first embodiment only in the engine type, and the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 3, the engine 115 that is the prime mover of the motorcycle 101 is, for example, a water-cooled four-stroke V-type two-cylinder engine, and is arranged with the crankshaft parallel to the left-right direction, and substantially from the front end of the crankcase 116. The front cylinder 117f is erected forward, and the rear cylinder 117r is erected substantially upward from the upper part of the crankcase 116. The transmission case 18 is continuously provided behind the crankcase 116.

  A radiator 39 is disposed in front of the front cylinder head 117fa, an air cleaner case 40 is disposed above the radiator 39, and intake pipes 142 branching from the throttle body 41 connected to the rear portion of the air cleaner case 40 extend. The front cylinder head 117fa is connected to the upper intake port and the rear cylinder head 117ra front is connected to the intake port. In addition, exhaust pipes 143 are connected to the exhaust ports at the lower part of the front cylinder head 117fa and the rear part of the rear cylinder head 117ra, and the exhaust pipes 143 gather together at the rear of the engine 115 and then rise obliquely upward and rearward. 44.

  The front lower engine hanger 63 below the lower down pipe 59 is fastened to and supports the lower front portion of the crankcase 116 of the engine 115 at the frontmost engine mount portion C1. Further, the rear upper engine hanger 67 at the rear end portion of the main pipe 65 is connected to and supported by the rearmost engine upper portion C2 of the transmission case 18 of the engine 115 at the rearmost engine mount portion C2. Furthermore, the front upper engine hanger 68 at the front of the main pipe 65 is fastened to and supported by the third engine mount C3 on the front upper side of the crankcase 116 of the engine 115. Here, the front upper engine hanger 68 and the third engine mount C3 are located between the front and rear cylinders 117f and 117r in a vehicle side view.

  When viewed from the side of the vehicle, the ground contact portion FT of the front wheel 3 of the motorcycle 101, the foremost engine mount portion C1 of the front lower engine hanger 63, and the rearmost engine mount portion C2 of the rear upper engine hanger 67 are The exhaust muffler support portion C4 in the muffler hanger 74 and the crankshaft portion CJ in the engine 15 are also substantially on the straight line L when viewed from the side of the vehicle. Further, the third engine mount portion C3 in the front upper engine hanger 68 is provided above the straight line L by being separated by a predetermined amount.

  As described above, in the motorcycle 101 in the second embodiment, the engine 115 supported by the vehicle body frame 6 is a V-type engine having the front and rear cylinders 117f and 117r, and the third engine mount C3 is the front and rear. By disposing between the cylinders 117f and 117r, it is possible to efficiently secure the engine support rigidity when a high-performance and narrow V-type engine is mounted.

The present invention is not limited to the above-described embodiments, and for example, a configuration in which the third engine mount C3 is disposed below the straight line L may be employed. Further, the main frame 12 may be extended to the rear of the swing arm pivot to constitute a part of the seat frame 13.
The configuration in the above embodiment is an example of the present invention, and the engine type and the detailed configuration of the vehicle body frame 6 are not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. Needless to say.

1 is a side view of a motorcycle according to a first embodiment of the present invention. FIG. 6 is an operation explanatory diagram of the motorcycle. It is a side view of a motorcycle in the second embodiment of the present invention.

Explanation of symbols

1,101 Motorcycle (Low-floor type vehicle)
2 Low floor 3 Front wheel 6 Body frame 7 Head pipe 9 Rear wheel 11 Down frame 12 Main frame 13 Seat frame 15,115 Engine 18a Swing arm shaft support 25 Swing arm 44A Exhaust muffler 58 Upper down pipe (upper frame member)
59 Lower down pipe (lower frame member)
C1 Frontmost engine mount C2 Last engine mount C3 Third engine mount C4 Exhaust muffler support FT Front wheel grounding part RT Rear wheel grounding part CJ Crankshaft part L Straight line

Claims (6)

Is disposed an engine (15, 115) supported on the body frame (6) in the vicinity of the low-floor portion is footrests (2), a rear portion of the engine (15, 115) and rear wheel (9) a swing arm for rotatably supporting (25) is pivotally supported, the body frame (6) is, upper down pipe (58) extending obliquely downward and rearward branches to the left and right from the upper portion of the head pipe (7) and A down frame (11) consisting of a lower down pipe (59) branched from the lower part of the head pipe (7) to the left and right and extending obliquely downward and rearward at a slightly steep slope from the upper down pipe (58 ), and the lower down pipe ( a main frame (12) comprising an upper of the from the lower engine (15, 115) from the main pipe (65) extending rearward of the 59), obliquely upward and rearward from a rear portion of the main frame (12) In the low floor type vehicle (1, 101) comprising and a seat frame (13) extending,
The main pipe (65) has a front end joined to the lower part of the lower down pipe (59) from the rear, and a lower end of the upper down pipe (58) joined to the front from above, and The upper part of the engine (15, 115) extends from the upper front part to at least the upper part of the swing arm shaft support part (18a) , and the intermediate part is provided curved so as to protrude upward in a side view of the vehicle .
The seat frame (13) includes a left and right seat pipe (70) that extends obliquely upward and rearward from the vicinity of the curved portion of the left and right main pipe (65) and has a bent portion at an intermediate portion, and the rear of the left and right main pipe (65). Left and right rear pipes (71) extending obliquely upward and rearward from the end, a rear side plate (72) for connecting the rear part of the seat pipe (70) and the rear part of the rear pipe (71), and the rear end of the main pipe (65) A rear gusset pipe (73) extending obliquely upward and rearward from the portion and coupled to the bent portion of the seat pipe (70),
The engine mount portion of the end portion (C2) provided on the rear portion of the main pipe (65), an engine mount portion of the foremost part (C1) provided at the lower end of the lower down pipe (59),
The foremost engine mount portion (C1) is located on a line (L) connecting the rearmost engine mount portion (C2) and the ground contact portion (FT) of the front wheel (3) in a vehicle side view ,
The upper part of the engine (15, 115) is supported above the line (L) in the vehicle side view and in the vicinity of the junction with the upper down pipe (58) at the front of the main pipe (65). Three engine mounts (C3)
In the swing arm (25), the front inner sides of the left and right arm members (27, 28) are connected by a cross member (29), and the cushion connecting portion (29a) is directed upward to the cross member (29). Between the cushion connecting portion (29a) and the intermediate portion in the longitudinal direction of the main frame (12). A low floor vehicle , wherein the cushion unit (30) is disposed so as to straddle the engine mount (C2) in the front-rear direction .   The low-floor type vehicle according to claim 1, wherein a crankshaft portion of the engine is positioned on the line in a side view of the vehicle.   The low-floor type vehicle according to claim 1 or 2, wherein a support part of the exhaust muffler of the engine is located on the line in a side view of the vehicle and above the grounding part of the rear wheel. The low floor type vehicle according to any one of claims 1 to 3, wherein the lower down pipe is provided so as to be substantially orthogonal to the line in a side view of the vehicle. The low engine according to any one of claims 1 to 4 , wherein the engine is a V-type engine having front and rear cylinders, and the third engine mount portion is disposed between the front and rear cylinders. Floor vehicle. The body frame according to claim 1, wherein the no frame members extending from the down frame beneath the engine, and no frame members extending downward from the main frame at the engine rear The low floor type vehicle according to any one of 1 to 5 .

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