JP5246462B2 - Motorcycle - Google Patents

Description

  The present invention is suitable mainly for an on / off dual-purpose motorcycle in which both on-road (paved road) and off-road (waste ground) are set as a road surface to be traveled, and more preferably trial running is also possible. The present invention relates to an on / off type motorcycle.

  As the above-mentioned on / off combined type motorcycle (hereinafter abbreviated as “on / off vehicle”), those disclosed in Patent Document 1 and Patent Document 2 are known. In an on-off vehicle disclosed in Patent Document 1 (also referred to as a “trailer vehicle” or “dual-purpose vehicle”), an engine portion having a cylinder and a cylinder head cover is disposed on the front of the transmission case, and the piston is vertically moved. A reciprocating engine, that is, an upright or almost upright engine with a transmission case is mounted between the front and rear wheels, and a rear wheel suspension system with a link mechanism is connected to the transmission case and the rear wheel (rear tire). The structure which arrange | positions and accommodates before and after is taken. In this case, a shock absorber (cushion unit), which is a main component of the rear wheel suspension device and includes a winding spring and a damper, is disposed in a vertically oriented posture.

  The on / off vehicle of Patent Document 2 is an on / off vehicle capable of trial running (hereinafter, abbreviated as “TR vehicle”), and a two-cycle with a substantially upright mission case in which a cylinder is disposed on the front of the mission case. An engine is mounted between the front and rear wheels, and a rear wheel suspension device with a link mechanism is arranged between the front and rear of the transmission case and the rear wheel. In this case, the shock absorber, which is the main component of the rear wheel suspension device, is disposed between the rear wheel and the engine portion in a slanting posture (forward leaning posture) that rises forward, and the front end portion of the shock absorber is It is pivotally connected to the body frame at a position behind the upper end of the cylinder.

  In common with these on-off vehicles, there are problems that the distance between the front and rear axes (which is a so-called wheel base, hereinafter abbreviated as “axial distance”) tends to be long, and the position of the center of gravity tends to be forward. In other words, in order to equip the rear wheel suspension shock absorber and its link mechanism between the front and rear of the engine at the center of the vehicle body and the rear wheel, the length of the swing arm must be considerably increased. is there. The swing arm is a component that supports the rear wheel rotatably at the rear end portion thereof, and the front end portion is pivotally supported by the pivotal support portion of the vehicle body frame so as to swing up and down. Next, the reason why the swing arm (hereinafter abbreviated as “swing arm”) becomes long will be described.

  Normally, the swing arm is formed by connecting and integrating a pair of left and right arm portions arranged on the left and right sides of the rear wheel with sufficient strength on the front end side (the pivot support side). Securing a certain longitudinal length to provide a connecting structure between them, determining the distance between the engine and the rear wheel in consideration of the weight balance in the longitudinal direction, the suspension stroke (cushion stroke) of the rear wheel, The length in the front-rear direction is set based on various design factors such as proper balance with the swing angle of the swing arm, and various conditions such as their interrelationships. In this case, the longer the length of the swing arm, that is, the longer the arm length, the more disadvantageous the strength and weight of the swing arm. Is desirable.

  However, in a structure in which shock absorbers with a link mechanism are arranged between the front and rear of the engine and the rear wheel as in the conventional on / off vehicle shown in Patent Documents 1 and 2, the arrangement space and the movement of the shock absorbers and the link mechanism are movable. In order to secure a space, the length of the swing arm must be longer than the minimum value determined by the above-described method, which is the reason for the “problem” described above. That is, the distance between the front and rear of the engine and the rear wheel becomes longer and the ratio with respect to the axial distance becomes larger, which causes problems such as forward tendency (forward balance) and longer axial distance.

In particular, the front and rear tire sizes are large (front wheel: equivalent to 2.75-21, rear wheel: equivalent to 4.00-18) and the axle distance is set to a relatively short value (1300 to 1350 mm) for the car grade. In order to ensure excellent rear wheel suspension performance, only a shock absorber with a link mechanism or a shock absorber (sometimes referred to as a direct mount type) is placed between the front and rear of the engine with a mission case and the rear wheel. In other words, the engine with a mission case is an upright type, and the position of the upright type engine is limitedly moved forward in the space between the front and rear wheels. Therefore, there is a disadvantage that it becomes difficult to perform the steering operation such as the heavy weight of the steering operation or the steep downhill traveling tends to become unstable because the front part of the vehicle body becomes heavy (forward balance). Problems such as heavy front-up and front hop were difficult.
Japanese Patent Laid-Open No. 10-67375 JP-A-5-131964

  In view of the above situation, a first object of the present invention is to provide a motorcycle having a transmission case with a transmission case disposed between a front wheel and a rear wheel and transmitting a driving force of the engine to the rear wheel. In addition, since the configuration for obtaining good rear wheel suspension performance is adopted, the above-described tendency for the front weight is corrected, and a good front-back weight balance is realized to improve the handle operability.

  By the way, the motorcycle having the structure disclosed in the above-mentioned Patent Document 1 has a problem that it is difficult to increase the fuel tank capacity. In other words, in a motorcycle having an upright engine, a fuel supply device such as a carburetor is disposed at a relatively high position (eg, a height level equivalent to the cylinder head). In the case of adopting a general fuel supply structure that guides the fuel to the fuel supply device, the fuel tank is disposed further above the fuel supply device that is disposed at a relatively high position in the vehicle body. If the fuel tank is set to a large size, the position of the center of gravity when the tank is full is increased, and the above-described tendency of the front weight is further increased, resulting in further deterioration of the handle operability. For this reason, it has been difficult to increase the fuel tank capacity. In particular, the disadvantage tends to increase in a motorcycle equipped with an upright four-cycle engine in which the engine height is higher than that of a two-cycle engine. In addition, this is a serious problem in TR cars that require lightweight and light steering operation.

  Therefore, the second object of the present invention achieves the first object described above, and suppresses or avoids the increase in the capacity of the fuel tank from increasing the position of the center of gravity and incurring further preload. However, it is in the point of obtaining a motorcycle that makes it possible.

In the invention according to claim 1, an engine E with a transmission case m is disposed between a front wheel 1 and a rear wheel 2, and a transmission mechanism 3 for transmitting the driving force of the engine E to the rear wheel 2 is provided. Motorcycles
The rear wheel 2 is supported so as to be rotatable, and the vehicle body frame F and the rear swing arm 12 are pivotally supported by the vehicle body frame F so as to be swingable about a left and right fulcrum P provided at the front end portion. A shock absorber for wheel suspension is disposed in a substantially horizontal front-and-back posture directly above the transmission case m in such a state that there is almost no gap between the transmission case and the transmission case m in the vertical direction. It is directly connected to the moving arm 12, and most of the transmission case m is of an on-off or off-road type provided at a height position higher than the axis 2p of the rear wheel 2. Features.

The invention according to claim 2 is the motorcycle according to claim 1,
The vehicle body frame F includes a first suspension stay 54 for bolting the rear portion of the transmission case m, and a second suspension stay 55 for bolting an engine portion e having the cylinder 15 in the engine E. In addition, the shock absorber CU is connected to a bracket 44 attached to both the first suspension stay 54 and the second suspension stay 55 .

The invention according to claim 3 is the motorcycle according to claim 1 ,
The engine E is configured to be a lying type in which the cylinder 15 is positioned in front of the transmission case m and the piston movement direction line a in the cylinder 15 is horizontal, substantially horizontal, or a forward tilt angle close to horizontal in a side view. It is characterized by being.

[0014]
The invention according to claim 4 is the motorcycle according to claim 3 ,
The side frames 23 and 24 having the left and right fulcrum P on which the swing arm 12 is pivotally supported and the front end portion of the rear wheel 2 are set in a positional relationship where they overlap in a side view .
【Effect of the invention】

According to the invention of claim 1, the details will be described in the section of the embodiment. Rear wheel suspension performance and C.I. B. While improving maneuverability It becomes possible to improve the preload tendency.
First, the effect B. The main points are as follows: a. A rear-wheel suspension shock absorber installed between the swing arm and the vehicle body frame is arranged in a substantially horizontal front-rear posture immediately above the transmission case in a state where it is directly connected to the swing arm. The space for placing the link mechanism between the left and right fulcrum) and the rear wheel or the amount of expansion / contraction movement (stroke) of the shock absorber is no longer required. → The weight balance in the front-rear direction is improved, and the tendency for front weight is eliminated.
Next, effects A. The main points are as follows. → The point of action of the rear wheel suspension shock absorber on the body frame approaches the swing arm fulcrum → The inertia moment around the swing arm fulcrum of the vehicle body due to the rear wheel suspension is reduced → The mass on the spring is relatively heavy (Relatively unsprung mass becomes lighter) → Rear wheel suspension performance is improved. In addition, C.I. The main points of the a. → Shock absorbers are placed close to each other's heavy transmission case → Mass concentration and low center of gravity can be achieved near the center of gravity of the car body → Moment of inertia around the car body center of gravity is reduced, improving the maneuverability of the car body Condition.
As a result, in a motorcycle having a transmission case with a transmission case disposed between the front wheels and the rear wheels and having a transmission mechanism for transmitting the driving force of the engine to the rear wheels, a configuration for obtaining good rear wheel suspension performance is adopted. Therefore, the on-off or off-road motorcycle that improves the handleability by realizing a good front-to-back weight balance, which has been corrected for the aforementioned front weight tendency, is provided with excellent rear wheel suspension performance. can do.

In this case, as in the fourth aspect of the invention, it is advantageous if the side frame having the left and right fulcrum on which the swing arm is pivoted and the front end portion of the rear wheel are set in a positional relationship that overlaps in a side view.

According to the second aspect of the present invention, as will be described in detail in the section of the embodiment, the rear wheel suspension shock absorber is provided for suspending the engine with a transmission case on the vehicle body frame. It is connected to the bracket means using both of the second suspension stays, and it is possible to reduce the number of parts and reduce the cost by sharing the constituent members while achieving the effect of the invention of claim 1. There is an effect that the shock absorber can be connected to the vehicle body frame by the means.
In this case, if the bracket means is bolted to both the first and second suspension stays, the bracket means can be retrofitted and there is an advantage that the suspension performance and the like of the current model can be improved.

According to the invention of claim 3, which will be described in detail in the section of the embodiment, the shortening of the swing arm makes it possible to adopt a horizontal or overturning engine without increasing the axial distance. According to the first aspect of the present invention, It is possible to provide a motorcycle capable of further improving the maneuverability by promoting the lowering of the center of gravity while increasing the fuel tank capacity, or increasing the minimum ground clearance without increasing the position of the center of gravity.
Effect D. In other words, the adoption of a horizontal or ultra-forward engine → the position of a fuel supply device such as a carburetor is lowered → the bottom position of the fuel tank is lowered → the fuel tank capacity is increased. Since the fuel tank capacity can be increased without increasing the position of the center of gravity, it is possible to provide a motorcycle that can increase the cruising distance without oiling and can perform long-distance touring. In particular, a remarkable effect can be expected in a 4-cycle engine in which the engine length is longer than that in a 2-cycle engine.

Embodiments of a motorcycle according to the present invention will be described below with reference to the drawings. 1 to FIG. 3 are TR cars of Example 1, FIG. 4 is a TR car of Example 2, FIGS. 5 and 6 are TR cars of Example 3, FIGS. 9 and 8 are TR cars of Reference Example 1 , FIG. 11 shows a TR car of Reference Example 2 , FIGS. 12 to 15 show a TR car of Example 4 , FIGS. 7 and 16 show a TR car of Reference Example 3 , and FIGS. 17 and 18 show a TR car of Example 5 , respectively. 19 is a side view showing an effective space between the front and rear wheels in a conventional and a TR vehicle according to the present invention, FIG. 20 is a schematic diagram showing the main part of the rear-wheel suspension structure as three kinds of the center of gravity of the vehicle body, and FIG. It is a figure which shows the relationship graph of mass on a spring and lever ratio.

  In the motorcycle according to the first embodiment, as shown in FIGS. 1 to 3, an engine E is disposed between the front wheel 1 and the rear wheel 2 between the front wheel 1 and the rear wheel 2, and the rear wheel 2 having the rear wheel axis 2p is connected to the engine E. This is a TR vehicle having a transmission mechanism 3 for transmitting a driving force. In the figure, F is a body frame, CU is a rear wheel suspension buffer (cushion unit), 4 is a fuel tank, 5 is a seat for boarding, 6 is a silencer, 7 is a radiator, and 8 is a carburetor (fuel supply device). 1), 9 is a front fork, 10 is a front security device, 11 is a handle (steering handle), 12 is a swing arm for supporting a rear wheel, 13 is a rear security device positioned on the rear side of the rear fender 38, 14 Is a two-seater rear step mechanism. Reference numeral 56 denotes a metal plate such as an aluminum alloy or a synthetic resin under guard attached to the lower end portion of the vehicle body frame F, and protects the cylinder head 16 and the exhaust pipe 57 immediately after being taken out from the cylinder head 16. A front guard 58 may be provided. Further, a front cover 59 which is an external part and can protect the radiator 7 may be provided below the front part of the fuel tank 4.

  The engine E mounted on the TR car of the first embodiment is a four-cycle engine with a super-forward tilt type and a mission case m, and includes a single damper 21 and a coil spring 22 disposed on the outer periphery thereof. The shock absorber CU is disposed in a front and back recumbent posture that is substantially horizontal immediately above the mission case m. The front coupling part (the pivotal coupling part on the vehicle body side) fs of the shock absorber CU is provided on the left and right side frames 23 and 24 arranged so as to straddle the carburetor 8, and the rear coupling part (swing arm side) Rs is provided at the top of the swinging arm 12 having a substantially triangular shape in a side view. The oscillating arm 12 includes a main arm portion 12a, an oblique arm portion 12b extending forward and upward from the rear portion thereof, and an oblique arm portion erected from a position corresponding to the front portion of the main arm portion 12a. The vehicle body frame F is configured in a box shape having a support arm portion 12c coupled to 12b, and is swingable up and down by a swing arm fulcrum (an example of a left / right fulcrum) P provided immediately after the drive sprocket 20. It is pivotally connected to.

  The engine E is set to a super-front-inclined type (an example of an overturning type) four-cycle engine in which an engine part e connected to the front part of the transmission case m protrudes forward at an inclination angle of 15 degrees from the horizontal. The engine section e, which is a combustion section, includes a cylinder 15 that is screwed into the transmission case m, a cylinder head 16, and a head cover 17. Here, the inclination angle is an angle formed by a moving direction line a of the piston 18 in the cylinder 15 and a horizontal line, and a forward inclination angle close to horizontal in a side view is referred to as a super forward inclination. Incidentally, when the movement direction line a is horizontal (or almost horizontal), it is called a horizontal engine, and the range from the angle at which the movement direction line a slightly falls to the angle at which the movement direction line a slightly rises including the super forward tilt is expressed as “ The “horizontal, substantially horizontal, or a forward tilt angle close to horizontal” is defined as a fallen engine. Although not shown in the figure, the transmission case m includes a clutch, a gear transmission mechanism having a four to six-stage switching structure, an engine starting mechanism using an exterior kick pedal, a transmission operating mechanism using a change pedal, an oil pump, a cooling water pump, and the like. Equipped.

  The carburetor 8 is connected to the cylinder head 16 via a bent intake manifold 19 and is disposed at a position directly above the cylinder 15 in an upright posture or a slightly tilted posture. An insulator (not shown) for heat insulation may be interposed between the cylinder head 16 and the intake manifold 19 or between the intake manifold 19 and the carburetor 8. Further, a heat insulating sheet (not shown) may be disposed below the carburetor 8 in order to suppress or attenuate the radiant heat from the engine part e to the carburetor 8. Note that the intake manifold 19 itself may be formed of a material having a heat insulating action.

  As shown in FIGS. 1 to 3, the vehicle body frame F includes a head pipe (an example of a frame front end portion) 26 that supports the fork bracket 25 in a steerable manner, and a single main pipe that extends rearward and downward from the head pipe 26 ( Main frame member 27), left and right down tubes 28, 29 disposed across the engine part e, and left and right side pipes 23, 24 integrated with the rear end of the main pipe 27 The frame f and the rear frame r which is detachably attached to the main frame f are configured. The rear frame r includes left and right side tubes 30 and 31 that are bolted to the left and right side pipes 23 and 24, and left and right seat rails 32 and 33. In order to facilitate the assembly and removal of the engine E from the vehicle body frame F, the lower portion 28b of one of the left and right down tubes 28, 29 (eg, the left down tube 28) can be attached to and detached from the upper portion 28a. You may comprise in a desorption frame part. That is, the lower portion 28b is separated at a position immediately below a welding position with the reinforcing member 34 that connects and integrates the side pipes 23 and 24, and is attached to the upper portion 28a using a plurality of bolts. ing. Reference numeral 53 denotes a passenger footrest, and 60 and 61 denote first and second horizontal pipes that connect and integrate the left and right side pipes 23 and 24.

  The engine E includes a rear upper portion, a rear lower portion, and left and right side pipes 23 and 24 as a first suspension portion t1 and a third attachment portion t3, and left and right down tubes 28, 29 and the rear upper part of the cylinder head 16 are bolted and fixed to the vehicle body frame F as second mounting portions t2 which are also second suspension stays. Although illustrations and symbols are omitted, the left and right down tubes 28 and 29 and the front lower portion of the transmission case m may be connected as a fourth mounting portion. One of the first to third attachment portions t1 to t3 can be omitted. Although not shown in the drawings, a bracket 35 fixed to the left and right side pipes 23 and 24 is extended downward to form a front connection portion fs of the shock absorber CU, and the bracket extension portion is provided at the front front of the transmission case m. It is good also as a structure which bolts and suspends a part.

  As shown in FIG. 2, the center line of the expansion / contraction movement part of the shock absorber CU and the vector line X that is an extension line thereof are configured to pass between the vehicle body center of gravity G and the swing arm fulcrum P in a side view. Yes. The center line X of the extension / contraction moving part is the center line of the piston rod (not shown) of the damper 21. The vehicle body center of gravity G is, in a narrow sense, the portion of the vehicle body excluding unsprung parts such as the front and rear wheels, that is, the center of gravity of the sprung portion. Define that there is. The vehicle body center of gravity G of the TR vehicle according to the first embodiment is located around the lower portion of the carburetor 8 as an example, as shown in FIG.

  The vector line X indicated by the solid line indicates that the equipment is in an empty state, and the vector line X indicated by the one-dot broken line indicates that the rear wheel 2 is in the most suspended stroke, that is, the shock absorber CU is in the most compressed state. In any case, it passes between the center of gravity G of the vehicle body and the swing arm fulcrum P. By the way, the vehicle body center of gravity in the broad sense is the center of gravity of the entire motorcycle excluding the unsprung portion on the rear wheel side, and is located slightly forward and downward from the position of the vehicle body center of gravity G in the narrow sense. In addition, the equipment empty state means a state in which engine oil (mission oil), cooling water, fuel, and the like are filled (with a battery, an electrolyte is included) and the vehicle is not on board.

  The direction of the vector line X accompanying the expansion / contraction movement (stroke) of the shock absorber CU (that is, the direction of the force pushing the vehicle body around the swing arm fulcrum P) is closer to the vehicle body center of gravity G or closer to the swing arm fulcrum P than the vehicle body center of gravity G. Since it is set so as to be close to the position, the inertia with respect to the swing arm fulcrum P of the vehicle body caused by the expansion and contraction movement of the shock absorber CU due to the swing of the swing arm 12 when the rear wheel 2 passes through the unevenness or the like. The moment can be made extremely small. For example, when the rear wheel 2 climbs over a protrusion such as a stone during traveling, the feeling of pushing up through the seat becomes light and the ride comfort is improved, or the ride over the step which is one of the trial driving (staircase) The rear wheel suspension performance has been improved, for example, the rear wheel grip is improved and a higher step can be exceeded. The rear wheel suspension performance according to the present invention is further improved compared to a conventional TR vehicle (see FIG. 19A) having a shock absorber CU disposed in an obliquely vertical posture between the upright engine and the rear wheel. As a result, a rear wheel suspension device with excellent performance has been realized.

  As can be seen from FIG. 2, as the suspension stroke of the rear wheel 2 increases, the direction of the vector line X of the shock absorber CU approaches the swing arm fulcrum P (the interval between the vector line X and the vehicle body center of gravity G increases). To change. That is, it is possible to obtain a preferable characteristic that as the stronger suspension impact such as jump is applied, the inertia moment caused by the rear wheel suspension is changed to a smaller side. That is, the closer the direction of the vector line X is to the swing arm fulcrum P, the greater the force itself that the shock absorber CU compressed by the rear wheel suspension pushes the vehicle body, but the action point, that is, the swing of the front connecting portion fs. The radius around the moving arm fulcrum P becomes smaller. Therefore, according to the theorem concerning the moment of inertia that the moment of inertia about the axis of the object is the product of the mass of the object and the square of the distance from the axis of the part, the moment of inertia proportional to the square of the radius is The direction of the vector line X becomes smaller as it approaches the swing arm fulcrum P, and the influence of turning the vehicle body around the swing arm fulcrum P due to the rear wheel suspension becomes smaller. In particular, the sprung mass is increased, and as a result, the rear wheel suspension performance is improved.

  In addition, as an interpretation of the phrase “the center line of the expansion / contraction moving part of the shock absorber CU or its extension line X is configured to pass through the vehicle body gravity center G or its vicinity in a side view”, “at least the rear wheel 2 of The vector line X in the maximum suspension stroke state may be configured to pass between the vehicle body gravity center G of the sprung portion and the swing arm fulcrum P or in the vicinity of the vehicle body gravity center G of the sprung portion. Even with a simple configuration, a sufficient effect (an effect of improving the rear wheel suspension performance) can be obtained.

  As shown in FIG. 1, it is convenient to use a TR vehicle having a configuration in which a seat device S (shown by a broken line) is detachably mounted. The seat device S includes a rear safety device 13 having a taillight (which may include a stoplight), a winker (direction indicator light), and a support plate for attaching a license plate, and a first seat 5 having a sufficient cushion thickness. The integrated structure is configured so that it can be attached to the vehicle body frame F, kept locked, and removed by an attachment mechanism (not shown) having a fitting structure and a locking device for preventing detachment. The body frame F is provided with a flat, extremely small second seat 36 having a small cushion thickness, and a seat device S is detachably mounted above the second seat 36. Therefore, if the seat device S is removed, the play specification can be changed to a play specification suitable for trial running equipped with the second seat 36. In FIG. 1, the seat device S removed from the vehicle body frame F is indicated by a solid line, and the state of being mounted on the vehicle body frame F is indicated by a broken line.

  In other words, as a general specification equipped with the seat device S, a comfortable seating posture suitable for boarding and a comfortable riding posture with less knee bending by the first seat 5 that can obtain a good riding comfort, such as a general public road or a forest road You can travel to. When performing trial play or the like outside a general public road such as a riverbed or an off-road field, a play specification in which the seat device S is removed and a minimal and flat second sheet 36 (indicated by a virtual line) is exposed. Can be easily switched to. By switching to the play specification, the seat height is reduced and the rear part of the vehicle body is slimmed and lightened, so that trial running can be performed comfortably. Of course, the general specification can be used for trial driving such as play and forest road driving including the same, but in order to perform more trial-like driving, the seat specification S is removed as described above. It is easier to ride.

[Comparison of engine space]
FIG. 19 shows a TR vehicle of the present invention (FIG. 19B) having the ultra-forward engine E shown in FIG. 1 and a shock absorber CU arranged just above the transmission case, and the upright engine E and the transmission case. The effective space between the front and rear wheels (mainly the upper space of the engine) in each of the conventional TR vehicle (FIG. 19A) having the diagonally upward and downward shock absorber CU is shown as a hatched portion. In each figure, the outline of the maximum space that can be secured in a side view between the front and rear wheels is indicated by a dashed line z, and the space above the engine E, carburetor 8, and shock absorber CU is required from the line z and the like. An effective space with a design gap is shown as a hatched portion. The upper limit part of the line z depicts a standard shape as a TR car. In addition, the front and rear wheels 1 and 2 indicated by phantom lines indicate the positions of the most suspended stroke state (maximum pressure state).

  In the case where the axial distance Wj of the conventional TR vehicle and the axial distance W of the TR vehicle of the present invention are the same (Wj = W), a portion that can be used as a space for arranging auxiliary equipment such as a fuel tank or an air cleaner, It can be understood that the hatched effective space is easier to obtain with the TR car according to the present invention. In the conventional apparatus shown in FIG. 19A, the shock absorber CU in the obliquely up and down posture and the engine part e protruding upward are greatly digged into the space surrounded by the line z, and accordingly, the carburetor 8 is also installed at a high position. ing. For this reason, the effective space to which hatching is applied becomes smaller and is divided into front and rear. It seems that there is an effective space in the front part of engine E (without hatching), but it cannot be used as a place for disposing parts other than frame pipes and exhaust pipes, that is, auxiliary equipment for securing engine cooling air. Therefore, the effective space becomes smaller than expected.

  On the other hand, according to the present invention shown in FIG. 19 (b), the super forward tilt or horizontal engine E is disposed at a low position substantially along the bottom of the line z, and the carburetor 8 and the forward / backward-facing lying posture are directly above it. It is a “low position intensive structure” in which the shock absorbers CU are arranged, and a large effective space can be secured above them. The center of gravity can also be achieved. Therefore, the effective space between the front and rear wheels can be substantially expanded without changing the height (upper limit of line z) and the minimum ground height as a TR vehicle, and the capacity of the fuel tank, air cleaner, muffler, etc. is increased. , Low center of gravity or mass concentration can be promoted.

  In the conventional TR vehicle shown in FIG. 19 (a), the vector line X of the shock absorber CU is located at a position far away from the vehicle body center of gravity G by a distance j with a distance j (the swing arm with respect to the vehicle body center of gravity G). The structure is directed to the side opposite to the fulcrum P existence side. Therefore, the magnitude of the moment of inertia related to the swing arm fulcrum P of the vehicle body caused by the rear wheel suspension is larger than that of the conventional TR vehicle shown in FIG. 19 (a). It can be seen that the present invention is superior not only in the advantages related to the effective space described above but also in the rear wheel suspension performance. The advantages related to the effective space can also be obtained in each of the TR cars of Examples 2, 3, 6 and 8, which will be described later.

  19 (a) and 19 (b), the axial distances are Wj, W, the front-rear distance between the engine center of gravity eg and the rear wheel center 2p is Dj, D, and the height of the vehicle body center of gravity from the ground is Aj, A, where the height of the engine center of gravity from the ground is represented as Bj, B, the longitudinal distance between the vehicle body center of gravity G and the rear wheel center 2p is represented as N, Nj, and when Wj = W, D <Dj , A <Aj, B <Bj, and N <Nj. In other words, the TR vehicle according to the first embodiment has both the engine center of gravity eg and the vehicle body center of gravity G lower than the conventional TR vehicle, and is excellent in maneuverability. It is located near the rear. As a result, it can be understood that the front weight tendency is improved, and optimization of the front and rear weight balance can be further promoted.

  As shown in FIG. 4, the motorcycle according to the second embodiment is modified to a semi-competitive specification capable of running on a public road based on the TR car according to the first embodiment. That is, the upper limit position of the fuel tank 4 is lowered, the portion located behind the carburetor 8 is downsized, the air cleaner (not shown) is downsized, the rear frame r is changed, etc. By reducing the necessary space, the set height position of the second sheet 36 is made lower than the play specification shown in FIG. The fuel tank 4 is changed to a small one with a small tank capacity (2 to 4 liters), and the rear safety device 37 is further reduced to a minimum size as compared with the rear security device 13 of the first embodiment. It is structured to be detachably mounted on the rear end portion of the rear fender 38. Other configurations are substantially the same as those of the TR car of the first embodiment.

  This semi-competition-specification TR car is a specification that is suitable for riding in which trial driving is mainly used and public road driving is subordinate. For example, it is necessary to travel on public roads and forest roads while traveling. It is suitable for touring trials that compete by running through the section provided in the place, and adventure driving that runs on steep forest roads and mountain trails. In this case, although not shown, in consideration of a certain level of riding comfort, the second seat 36 is provided with a cushion thickness of about the middle between the second seat 36 shown in FIG. 1 and the first seat 5 shown in FIG. You may comprise in the medium-sized sheet | seat which has front-back length.

  As shown in FIGS. 5 and 6, the motorcycle according to the third embodiment is basically the same as that according to the first embodiment except that the body frame F and the layout structure around it and the engine type (cooling structure) are slightly different. Similarly, it is configured as a TR car of a general specification that can be switched to a play specification. Accordingly, parts different from those of the first embodiment will be mainly described, and the same functions and structures as those of the first embodiment are denoted by the same reference numerals and the description thereof is made. The TR car according to the third embodiment swings the carburetor 8 to the right as a left-right asymmetric body frame F that lowers the position of the left side pipe 23 and raises the position of the right side pipe (positioned close to the right side), The aim is to increase the fuel tank capacity and lower the center of gravity. The detachable seat device S of the first embodiment may be employed in the TR car of the third embodiment.

  As shown in FIG. 6, the main pipe 27 extends rearward and downward as compared with that of the first embodiment (see FIG. 3), and the rear portion is bent slightly to the left from the front and rear intermediate portions in plan view, and is eccentric. The front connecting portion fs of the shock absorber CU is formed in the extension portion 27e that is offset to the left. For example, the shock absorber CU disposed with a distance α offset from the vehicle body center T in the left-right direction by the mounting plate 62 welded to the right wall surface of the extension 27e and the boss member 63 that is welded and supported by the left side pipe 23. The bolts are connected to form a front connecting portion fs. The left side pipe 23 is a relatively short pipe having an upper part that is bent to the right with a small curvature from the lower part where the swing arm fulcrum P is formed and welded in the vicinity of the extension 27e. Reference numeral 24 denotes a long portion extending forward in a state of detouring slightly upward, and is welded to the main pipe 27 at a location slightly away from the front of the carburetor 8. The carburetor 8 is disposed so as to be slightly biased to the right by twisting the intake manifold 19 to the right, and is disposed between the left and right of the rear portion (extension portion 27e) of the main pipe 27 and the right side pipe 24 in plan view. Although the eccentric amount of the carburetor on the right side (lateral direction) is reduced by slightly decentering the rear part of the main pipe 27 to the left side, the carburetor 8 is placed between the main pipe 27 and the right side pipe 24 that are straight forward and backward. You may take the structure to arrange | position.

  In the TR car of the third embodiment, an air-cooled (or water-cooled) four-cycle engine is mounted, and large cooling fins (not shown) are formed in the cylinder 15 and the cylinder head 16. Compared to the water-cooled engine shown in Example 1, the outer shape of the engine part e is enlarged. Further, since the space portion on the front side of the down tubes 28 and 29 is vacant above the cylinder portion e where the radiator is disposed in the first embodiment, the space is arranged for the arrangement of auxiliary equipment such as an exhaust pipe and an air cleaner. It can be used as a place. The left and right shape of the fuel tank 4 and the shapes of the left and right front covers 59 and 59 are asymmetrical. As described above, advantages (actions and effects) when compared with the TR vehicle (motorcycle) according to the configuration of the first embodiment are as follows. The configuration of the side pipes 23 and 24 can be reversed left and right (therefore, the swing direction of the carburetor 8 and the shape of the fuel tank 4 can also be reversed left and right). Reference numeral 64 denotes a reinforcing pipe that connects an intermediate portion of the main pipe 27 and the upper end of the head pipe 26.

  When the position of the right side pipe 24 is high, the degree of exposure of the right side surface portion of the carburetor 8 is increased, the cab operation such as the rotation operation of the slow screw and the maintenance are easy, and the exhaust pipe is taken out to the right side of the engine. In this case, the degree of freedom in the layout of the exhaust pipe behind the exhaust pipe is increased. Since the front side portion of the left side pipe 23 is shortened, the left side portion of the fuel tank 4 with respect to the main pipe 27 can be expanded further inward and rearward, and the right side pipe 24 is lifted upward. Even considering the resulting reduction in tank capacity, the capacity of the fuel tank 4 as a whole can be increased. Further, since the extended portion 27e at the rear end of the main pipe 27 can be used as a constituent member of the front connection portion fs of the shock absorber CU, a dedicated frame portion for supporting the front connection portion fs can be eliminated (or downsized), and more rationally. It becomes possible to set it as a typical structure.

[ Reference Example 1 ]
As shown in FIGS. 9 and 8, the motorcycle according to the reference example 1 includes a shock absorber CU in which a coil spring 22 is disposed around a damper 21 having a cylinder structure for suspension of the rear wheel 2. It is a TR car that adopts a so-called two-suspension structure in which a total of two are arranged in each of the above. The TR car of this reference example 1 is a structure that is a suspension of the first to third embodiments which are mono-suspension cars, and will be described with a focus on the rear wheel suspension structure. The same reference numerals shall be attached. For simplicity, FIGS. 9 and 8 are drawn with parts other than those necessary. A shock absorber CU indicated by a virtual line indicates a position when the rear wheel 2 has a maximum suspension stroke.

  The swing arm 12 includes a pair of left and right main arm portions 12a and 12a that extend linearly rearward and downward from the horizontal axis P, and a pair of left and right support arm portions 12b and 12b that extend upward and forward from the rear portion. And a single connecting arm portion 12d that connects the upper portions of the left and right support arm portions 12b in a state in which the plan view passing through the front of the rear wheel 2 is substantially U-shaped, and the front portion of the main arm portion 12a A box-shaped structure is provided that includes a single or a pair of left and right support arm portions 12c that are erected from a corresponding portion and are connected to the front portion of the connection arm portion 12d. The rear connection part rs of the shock absorber CU is provided at the upper end part of each support arm part 12b, 12b, and the front connection part fs is in a state straddling the left and right side pipes 23, 24 and the rear end part of the main pipe 27. Is provided. For example, as shown in FIG. 8, a stay plate 65 welded to each side pipe 23, 24 and a single pipe member 66 fixed to the rear end of the main pipe 27 are provided. The front coupling part fs of the shock absorber CU is configured to be bolted across 66.

  The main pipe 27 is a straight line made of a single square pipe material, and the carburetor 8 mounted by being swung to the right from the engine E slightly offset to the right is disposed on the right side of the main pipe 27. FIG. 9 shows an equipped empty state, and even in this state, the center line of the shock absorber CU or a vector line X that is an extension thereof passes between the vehicle body center of gravity G and the swing arm fulcrum P in a side view. It is configured. Naturally, the vector line X (virtual line) in the maximum suspension stroke state in which the shock absorber CU is contracted most passes far below the center of gravity G of the vehicle body. Even in this case, “a configuration in which at least the vector line X in the maximum pressure state of the rear wheel 2 passes between the vehicle body gravity center G and the swing arm fulcrum P or in the vicinity of the vehicle body gravity center G” is significant. It is.

[ Reference Example 2 ]
The motorcycle according to the reference example 2 is a two-suspension TR vehicle having a shock absorber CU on each of the left and right sides of the rear wheel 2 as shown in FIGS. For example, a two-suspension vehicle having a configuration according to the reference example 2 can be modified by modifying a TR car that is manufactured and marketed as a two-suspension car and can travel on a public road. The original rear wheel suspension device before the modification is shown in FIGS. 10 and 11, as indicated by phantom lines, where the rear tube r is connected to the side tubes 30 and 31 and the seat rails 32 and 33, and the swing arm 12. This is a configuration in which a shock absorber CU ′ in an upright posture that slightly tilts forward over the end portion is installed. In the second reference example , the same functional parts as those of the TR vehicle according to the first embodiment are denoted by the same reference numerals, and the description thereof is made.

As shown by the solid line in FIGS. 10 and 11, the rear wheel suspension device as the TR vehicle of Reference Example 2 has the rear wheel suspension buffer CU in a substantially lying posture at a position away from the main arm portion 12a. Has been deployed. That is, the side tubes 30 and 31 in the original state are cut from the vicinity of the connection portion to the upper end portion of the foot frame portion 40 having the swing arm fulcrum P connected to the lower ends of the side frames 23 and 24, Instead, reinforcing frame portions 41 and 42 that are installed and integrated by welding or the like are provided across the intermediate portions of the side frames 23 and 24 and the upper ends of the side tubes 30 and 31, and the reinforcing frame portions 41 and 42 are provided. A bracket 35 is provided to straddle the corresponding side frames 23 and 24. Then, a mounting stay 39 having a triangular shape in side view is attached to the upper side of the front and rear intermediate portion of the swing arm 12 by means of bolts, welding, and the like, and formed on the rear connection portion rs and the bracket 35 formed at the upper end portion thereof. The shock absorber CU is erected and connected to the front connection portion fs. One down tube 28 may be used.

  The mounting stay 39 is formed in such a size that the rear connecting portion rs is positioned at a position sufficiently above so that there is no interference with the chain 3 for driving the rear wheels 2, and the left and right shock absorbers. The CUs are set at the same position in the side view (the left and right positions may be different). Examples of the mounting stay 39 include a pair of left and right steel plates and an aluminum alloy plate, and a cast or forged integrated product (single member). However, other configurations of the pipe material may be used. Although details are omitted, the auxiliary equipment (exhaust pipe, air cleaner, etc.) that was originally placed with the change of the shock absorber CU and its mounting position is scraped off or moved to another position, or another shape. A process such as adding the one formed on is appropriately performed. Reference numeral 34 denotes a reinforcing frame material.

  FIGS. 10 and 11 show a state where the equipment is empty, and the center line of the expansion / contraction movement portion of the shock absorber CU composed of the damper 21 and the coil spring 22 or the vector line X which is an extension line thereof passes through the center of gravity G (or the vicinity thereof) of the vehicle body. In addition, in the maximum suspension stroke state of the rear wheel 2 (also referred to as a full stroke state or a maximum pressure state), the vector line X passes between the vehicle body center of gravity G and the swing arm fulcrum P as shown by a one-dot broken line. Yes. In this way, in the two suspension vehicle having the shock absorber CU on the left and right with respect to the rear wheel 2, the vector line X of the shock absorber CU is configured (remodeled) so as to pass through the vehicle body center of gravity G or the vicinity thereof. Compared to the original specification shown in Fig. 1, the rear wheel suspension performance is dramatically improved. Even in this case, the effect of sufficiently improving the suspension performance can be achieved with the configuration that “the vector line X in the maximum suspension stroke state of the rear wheel 2 passes between the vehicle body gravity center G and the swing arm fulcrum P or in the vicinity of the vehicle body gravity center G”. Can be demonstrated. Then, by setting the position of the rear connection part rs higher with respect to the swing arm 12, or by bringing the position of the front connection part fs closer to the swing arm fulcrum P, the vector line X is also displayed in the vehicle empty state. If it is configured to pass between the center of gravity G and the swing arm fulcrum P, the rear wheel suspension performance can be further improved.

  In the original two-suspension structure indicated by the phantom line, the vector line X ′, which is the center line of the shock absorber CU ′, is configured to face the distance g, that is, far away from the center of gravity G of the vehicle body. I understand that. On the other hand, in the configuration according to the present invention (after modification), as described above, the vector line X of the shock absorber CU almost passes through the center of gravity G of the vehicle body, and the relative sprung mass is greatly increased, so that the protrusion is overcome. The action of rotating the vehicle body forward around the swing arm fulcrum P due to the rear wheel suspension (such as the moment of inertia related to the swing arm fulcrum P of the vehicle body caused by the rear wheel suspension) is significantly reduced. Become.

  That is, in the original two-suspension structure indicated by the phantom line, the vehicle body clearly moves around the swing arm fulcrum P as the rear wheel protrudes, and the vehicle body is centered on the ground contact point of the front wheel 1. Although the rear part shows a large lifting behavior (the seat has a strong push-up feeling and the suspension performance is not good), in the two-suspension motorcycle according to the present invention indicated by the solid line, the sprung mass is relatively heavy, When riding on the convex part of the rear wheel, the compression amount of the shock absorber CU is increased, and the swing movement angle of the swing arm 12 with respect to the vehicle body is increased, so that most of the suspension stroke of the rear wheel 2 is absorbed. The rear lifting behavior is very small.

  Therefore, the rate at which the influence of the undulations and irregularities on the traveling road surface is transmitted to the spring is greatly reduced, and the rear wheel suspension performance is clearly improved, for example, there is almost no push-up feeling from the seat 5. In addition, the road surface grip of the rear wheel 2 is thereby improved, and there is also an advantage that it is possible to perform a rough driving on a steep slope or a trial driving that cannot be conventionally performed such as climbing over a step (eg, a steer case). The height of the limit becomes higher). The shock absorber CU ′ in the original two-suspension specification and the shock absorber CU in the specification according to the present invention have different specifications such as the amount of expansion / contraction movement, the spring constant of the coil spring 22 and the damping characteristic of the damper 21. Needless to say.

As shown in FIGS. 12 to 15, the motorcycle according to the fourth embodiment is a mono-suspension TR vehicle in which a single shock absorber CU is arranged in a forward and backward lying posture in front of the rear wheel 2. The motorcycle manufactured as the suspension TR vehicle can be modified to be a mono suspension vehicle having the configuration according to the present invention. The single shock absorber CU is reconfigured so as to be arranged immediately above the transmission case m between the front and rear of the engine part e and the rear wheel 2, and is indicated by a virtual line in FIGS. The original rear wheel suspension device (the shock absorber CU ′ and its mounting structure, etc.) before remodeling is the same as that in the case of the reference example 2 shown in FIGS. 10 and 11, and the description here is omitted.

  The swing arm 12 is linearly extended from the swing arm fulcrum P to the main arm portion 12a extending rearward and downward, the oblique arm portion 12b extending from the rear portion to the upper front and the front portion of the main arm portion 12a. A single or a plurality of support arm portions 12c that are erected from the corresponding portions and intersect with the front portion of the oblique arm portion 12b are added, and the oblique arm portion 12b is formed in front of the rear wheel 2. A single rear coupling portion rs is formed at or near the coupling point between the support arm portion 12c and the support arm portion 12c. A screw shaft (not shown) that is integrally mounted on the mounting plate portion 12e at the rear end of the main arm portion 12a to screw the rear end portion of the oblique arm portion 12b to the lower end portion of the original shock absorber CU '. You may use the means to screw.

  Regarding the structure of the front connection portion fs of the shock absorber CU, stays 23a and 24a that are integrally mounted on the front side of the side frames 23 and 24 by welding or the like, and fastening members (brackets) that are screwed to the 23a and 24a. 44) is additionally configured. The fastening member 44 is composed of a total of two parts, that is, a pair of left and right triangular plate members 44A and 44A integrally having a boss portion 44a, and also has a connecting member (not shown) for integrally connecting the triangular plate members 44A and 44A. It may be configured. A front connecting portion fs is configured by bolting a damper-side support portion (not shown) of the shock absorber CU between the left and right boss portions 44a, 44a located at all end portions of the triangular plate material 44A. ing. In the case of an erecting type or an erecting type four-stroke engine tilted slightly forward, a space is formed between the carburetor 8 disposed behind the cylinder head and the transmission case m, so that the space in front of the buffer CU Arrangement can be made with the part inserted. When the vertical dimension of the space is small, the carburetor 8 and the shock absorber CU are arranged with their relative positions shifted to the left and right. For simplicity, the right fastening member 44 is omitted in FIG.

12 and 13, the fastening member 44 is fastened together with the first suspension stay 54 for bolting the rear upper part to the stays 23a, 24a and for bolting the rear upper part of the engine E. The lower part of the rear part is bolted to the vehicle body frame F, and it is reasonably detachably mounted with the joint mounting structure with the first mounting part t1, but is fixed to the side frames 23, 24 by means such as welding. It is also possible to use means. In the fourth embodiment , since the single shock absorber CU is arranged at the center or almost the center position in the vehicle body width direction, the side tubes 30 and 31 are divided as in the case of the reference example 2 , and the modification such as the handling change is performed. It can be omitted. Although details are omitted, the auxiliary equipment (exhaust pipes, air cleaners, etc.) originally placed on the shock absorber CU at the center of the car body has been scraped, reshaped, etc. The process of moving to the position is appropriately performed.

  As shown in FIGS. 14 and 15, the fastening member 44 is fastened together with a second suspension stay 55 for suspending the rear end portion of the cylinder head 16 or the head cover 17 of the engine portion e, and One part is composed of two parts having a pair of left and right bracket plates 44A, 44A whose lower ends are fastened to one suspension stay 54, or a single part composed of these bracket plates 44A, 44A and a connecting member for integrally connecting them. It may be done. That is, it is a rational structure in which the first and second attachment portions t1 and t2 are used together. In this case, there is an advantage that the stays 23a and 24a (see FIG. 13) welded to the left and right side pipes 23 and 24 become unnecessary. In FIG. 13 and FIG. 15, the shock absorber CU is arranged at the center of the left and right. However, if it is easy to interfere with the lower part of the carburetor 8, it may be provided close to the side that does not interfere with the carburetor 8.

[ Reference Example 3 ]
As shown in FIGS. 7 and 16, the motorcycle according to Reference Example 3 is a two-suspension TR vehicle having a shock absorber CU on each of the left and right sides of the rear wheel 2. For example, a two-suspension vehicle configured as a reference example by remodeling a TR car that is manufactured and marketed as a two-suspension car and that can run on general public roads (a motorcycle of a different model from Examples 5 and 6). Is possible. In the original motorcycle before remodeling, from a single main frame portion 27 extending from the head pipe 26 which is the front end portion of the frame to the swing arm fulcrum P (lower rear portion of the engine E), and the lower end portion of the down tube 28, A pair of left and right side tubes 30, 31 extending over the conventional rear connection portion rs', a seat rail 32 having a substantially U shape in plan view, a lower end portion of the main frame portion 27, and intermediate portions of the side tubes 30, 31 Frame F having a horizontal pipe 43 connecting the two.

  First, lower reinforcement for cutting the upper and lower intermediate portions 30a and 31a of the rear portions of the side tubes 30 and 31 with a predetermined width, and connecting and integrating the upper end of the lower portion and the main frame portion 27 after cutting. The frame portions 45 and 45 are newly provided, and upper reinforcing frame portions 46 and 46 for connecting and integrating the lower end portion of the upper portion after cutting and the main frame portion 27 are newly provided. For example, a sturdy pipe material 47 penetrating left and right is provided at the upper and lower portions of the upper and lower reinforcing frame portions 46 and 45 in the vertical frame portion 27A of the main frame portion 27, and screw shafts ( The front connecting portion fs is configured by fixing the notation). The ground indicated by the phantom line (not shown) is the case of the conventional specification equipped with the original shock absorber CU ′, and the ground indicated by the solid line (not shown) is the case of the present invention. The position is relatively lowered to increase the suspension stroke of the rear wheel 2. As shown in FIG. 16, the vector line X of the shock absorber CU and the vector line X in the maximum suspension stroke state indicated by a one-dot broken line are both configured to pass between the vehicle body center of gravity G and the swing arm fulcrum P. Yes.

  On the other hand, the swing arm 12 is newly provided with a pair of left and right mounting stays 39, 39 that are connected and integrated at the rear part and the front and rear intermediate part, and a rear connection part rs is provided at the top of the mounting stays 39, 39, Thereafter, the shock absorber CU in the lying position is erected and connected across the connecting portion rs and the front connecting portion fs. As shown in FIG. 16, the mounting stay 39 includes an oblique arm portion 12b whose rear end portion is screwed to the original rear connecting portion rs ′ and a support portion fixed to the front and rear intermediate portions of the main arm portion 12a. A detachable structure having a support arm portion 12c whose lower end is screwed to 12f may be used, but a structure using a triangular plate as shown in FIGS. In addition, it is advantageous in terms of strength if a support member 48 (shown in phantom) that is disposed between the chain 3 and the rear wheel 2 and connects the main arm portion 12a and the front coupling portion fs or its vicinity is provided. is there. Although details are omitted, the auxiliary equipment (exhaust pipes, air cleaners, etc.) originally placed with the change of the shock absorber CU and its mounting position is scraped off or moved to another position, or in another shape. A process such as adding the formed one is appropriately performed. Further, the above-described modification processing of the side tubes 30 and 31 accompanying the change of the mounting position of the shock absorber CU is an example, and is not limited thereto.

As shown in FIGS. 17 and 18, the motorcycle according to the fifth embodiment is a mono-suspension TR vehicle in which a single shock absorber CU is arranged in a front-rear lying posture immediately above the transmission case m and in front of the rear wheel 2. It is. For example, a motorcycle manufactured as a two-suspension TR vehicle may be modified to form the monosuspension vehicle of the fifth embodiment . The original two-suspension rear wheel suspension before remodeling is the same as that of the reference example 3 shown in FIGS. 7 and 16, and description thereof is omitted here. The gist of the configuration (remodeling) related to the TR vehicle of the fifth embodiment is that a single shock absorber CU is directed forward and backward through a vertical portion 27A of a single main frame portion 27 extending between the frame tip portion 26 and the swing arm fulcrum P. The point is that it is placed in a lying position. In addition, it is also possible to adopt a configuration in which the single shock absorber CU and the single main frame portion 27 are displaced from each other on the left and right sides, and the vertical portion 27A is slightly recessed and connected without passing through the vertical portion 27A. It is. Note that reference numeral 67 in FIG. 18 denotes a cylindrical boss for pivotally supporting the swing arm 12 on the vertical portion 27A.

A portion slightly above the mission case m in the vertical portion 27A is cut off by a predetermined vertical dimension, and instead, a tunnel space portion ts is formed by welding reinforcement frame members 49 and 50 on the left and right sides thereof, and is passed therethrough. A single shock absorber CU is placed on the side. A pair of left and right brackets 51, 51 extending forward from the left and right reinforcing frame members 49, 50 is provided with a front connecting portion fs, and a swinging arm provided with an oblique arm portion 12b and a support arm portion 12c. A rear connection portion rs is provided at the intersection of the oblique arm portion 12b and the support arm portion 12c in the arm 12. For example, the mounting plate 52 is fixed to each of the reinforcing frame members 49, 50, the rear lower portion of the triangular plate-like bracket 51 is fastened together with the first mounting portion t1 for engine suspension, and the rear upper portion is attached to the mounting plate. 52 may be bolted to the structure. The side tubes 30 and 31 need not be changed or modified, or little. In addition, along with the modification, auxiliary machinery (exhaust pipe, air cleaner, etc.) that was originally placed should be processed appropriately, such as shaving, moving to another position, or adding another shape. Do. As shown in FIG. 17, the vector line X of the shock absorber CU is configured to pass between the vehicle body center of gravity G and the swing arm fulcrum P. Also in the motorcycles of Reference Example 3 and Example 5 , the same operations and effects as the motorcycles of Reference Example 2 and Example 4 can be obtained.

[Effects of rear wheel suspension in the present invention]
Here, the effect of the rear wheel suspension structure (rear wheel suspension device) of the motorcycle according to the present invention will be examined. From the conclusion, the configuration in which the shock absorber CU is directed toward the vehicle body center of gravity G means that the lever ratio between the expansion / contraction amount of the shock absorber CU and the suspension stroke amount of the rear wheel 2 is increased in practice while increasing the relative sprung mass. It is a point that can be set to a value that functions well. First, FIG. 20 shows a reference invention configuration K in which the shock absorber CU is directed to the vehicle body center of gravity G, and the shock absorber CU is directed to a location near the vehicle body gravity center G between the vehicle body gravity center G and the swing arm fulcrum P. 2 Each of the invention configuration Ki and the conventional configuration Ku in which the shock absorber CU faces away from the swing arm fulcrum P from the vehicle body center of gravity G are shown in a simplified manner. Note that FIG. 20 and FIG. 21 to be described later are sample diagrams extremely simplified for easy understanding of the suspension performance, and are not faithfully expressed based on the actual arrangement configuration, dimensions, and the like.

  In FIG. 20, the front connecting portion fs in the reference invention configuration K, the force H and the vector line X that the buffer CU pushes the vehicle body center of gravity G are fi, Hi, Xi in the second invention configuration Ki, and fu in the conventional configuration Ku. , Hu, Xu, and the displacement vector dimension in the direction orthogonal to the corresponding vector line between the pushing direction of the shock absorber CU and the vehicle body center of gravity G, and the corresponding vector line between the swing arm fulcrum P and the vehicle body center of gravity G. The intervals in the orthogonal direction are respectively referred to as di and Li in the second invention configuration Ki, and du and Lu in the conventional configuration Ku. In the reference invention configuration K, it is assumed that the shock absorber CU pushes the vehicle body frame with the force H by the upward force h acting on the rear wheel shaft center 2p due to overcoming the convex portion or the like. Under these conditions, the lever ratio of each component K, Ki, Ku, and the ratio of the relative sprung mass are obtained as follows. The inertia moment of the center of gravity G of the vehicle body with respect to the force of the shock absorber CU is I in the standard invention configuration K, Ii in the second invention configuration Ki, and Iu in the conventional configuration Ku.

In a case where the force that the shock absorber CU with the rear wheel suspension in the reference invention configuration K pushes the center of gravity G of the vehicle body is expressed as H and the moment of inertia I = Hr2, the pressing forces Hi, Hu and inertia in the second invention configuration Ki and the conventional configuration Ku The moments Ii and Iu are expressed as follows.
Hi = H * (Li-di) / Li = H * r / Li
Ii = Hi * Li = (H * r / Li) * Li = H * r * Li
Hu = H × (Lu + du) ÷ Lu = H × r / Lu
Iu = Hu × Lu = (H × r / Lu) × Lu = H × r × Lu
Here, as an example, the ratio of Li and Lu to r is determined by the drawing dimensions in FIG.
Li = 1.25r
Lu = 0.69r
Thus, Ii = 1.25I and Iu = 0.69I. This moment of inertia shall be read as “relative sprung mass”, and the relative sprung mass of each component K, Ki, Ku will be represented as M, Mi, Mu.

  The lever ratio Q is the ratio n / v of the expansion / contraction stroke amount v of the shock absorber CU to the design suspension stroke amount (wheel travel amount) n of the rear wheel 2, for example, the rear wheel suspension stroke amount. Is 180 mm and the expansion / contraction stroke amount of the shock absorber CU is 54 mm, the lever ratio Q = n / v = 54/180 = 0.3. It is empirically known that this lever ratio Q cannot be made physically small in order to function well and obtain the desired cushioning action. That is, the lever ratio Q is preferably set to about 0.33 (1/3) or more, that is, Q> 0.33 although it depends on the suspension stroke amount. For on / off vehicles, etc. with a large amount of suspension stroke (eg, 250 mm or more), the lever ratio Q may be set to about 0.25 (1/4) from the standpoint of arrangement space and link mechanism characteristics. Limiting Q> 0.25 is possible. Incidentally, most of the conventional motorcycles having a monosus structure as shown in FIG. 19 (a) have a link mechanism. The main reason for this is that the expansion and contraction of the shock absorber so that it functions substantially. The advantage is that the amount of movement (stroke) is amplified and a so-called progressive effect can be produced (easily produced).

  Here, the lever ratio Q will be described with reference to FIG. 19B. If the free length, which is the longest state of the shock absorber CU, is Ymax, and the most contracted maximum pressure length is Ymin, the expansion / contraction stroke amount v = Ymax−Ymin, and the suspension stroke n of the rear wheel 2 is the axial center when the shock absorber CU is a free length from the height position of the rear wheel shaft center 2p when the shock absorber CU is the maximum pressure length. The value obtained by subtracting the height position of 2p. Strictly speaking, the free length of the shock absorber CU is not the position shown in FIG. 19B (it is a position slightly lower than the figure), but for convenience of explanation, it is replaced with the position of the equipped empty state. Shall be shown.

  FIG. 21 shows an image of a relation graph in which the relative sprung mass M due to the moment of inertia I applied to the vehicle body center of gravity G by the shock absorber CU is plotted on the vertical axis and the lever ratio Q related to the rear wheel suspension is plotted on the horizontal axis. As shown in FIG. 21, the line Z indicating the relationship between the relative sprung mass M and the lever ratio Q is almost an inversely proportional graph or close to it, and when the lever ratio Q increases (the front connection of the shock absorber CU). When the part fr moves away from the swing arm fulcrum P), the relative sprung mass M becomes smaller (inertia moment I becomes smaller), and when the lever ratio Q becomes smaller (the front connection part fr of the shock absorber CU becomes the swing arm fulcrum). A relation is established that the relative sprung mass M is large (inertia moment I is large) as it approaches P.

  As described above, the larger the relative sprung mass M is, the better the rear wheel suspension performance is. Therefore, in order to improve the suspension performance, the line Z is set as close to the side where the relative sprung mass M is as large as possible. However, in terms of the lever ratio Q, it is desirable that the lever ratio Q is set to an oblique hatched portion where the lever ratio Q is equal to or greater than the first predetermined value (Q = 0.33). Therefore, it can be understood that the first predetermined value on the line Z or a position in the vicinity thereof may be set to satisfy both of these requirements. However, the position is such that the shock absorber CU faces the vehicle body center of gravity G. It almost agrees with the conditions at that time. This means that in claim 1 etc., “... the center line of the expansion / contraction moving part of the shock absorber or its extension line is configured to pass through the center of gravity of the vehicle body or its vicinity in a side view,” and As a result, a motorcycle having a rear wheel suspension device that functions effectively and exhibits excellent performance can be obtained.

  In order to further improve the suspension performance, the second predetermined value s2 that is closer to the upper side (left side) than the first predetermined value s1 in FIG. It is more preferable that, in claim 2, etc., “... the center line of the telescopic moving part of the shock absorber or its extension line passes between the left and right fulcrum and the center of gravity of the vehicle body in a side view. "..." Specifically, “… the center line of the expansion / contraction moving part of the shock absorber or its extension line passes through a portion where the lever ratio between the left and right fulcrum and the center of gravity of the vehicle body is a second predetermined value or more in side view. It is defined as "It is composed ...". An example of the second predetermined value s2 is 0.25 described above.

  The disadvantage of the lever ratio Q being too small is that the absolute expansion / contraction movement amount of the shock absorber CU is physically reduced and the error ratio on the suspension structure is increased, in other words, play in suspension operation. In other words, the stress increases due to excessive increase of the lever ratio and the strength of each part has to be significantly reinforced, and there is a practical limit. What is important in terms of performance is that the damper function cannot be secured. In other words, the damper 21 of the general shock absorber CU that uses resistance when fluid such as oil passes through the orifice is a mechanism in which a damping action occurs due to relative movement between the piston rod and the cylinder, and the amount of movement is too large. When it becomes smaller, attenuation does not substantially occur. That is, it can be said that the first predetermined value s1 and the second predetermined value s2 are provisions on the assumption that a general shock absorber CU having a combination of the damper 21 and the coil spring 22 is used. Note that the lever ratios Q (n / v) of the three configurations K, Ki, and ku in FIG. 20 are the same for the sake of simplicity, and exactly match the graph of FIG. 21 that is close to the actual situation. Absent.

Further examination based on the above, for example, the elastic means such as a coil spring and the damper means using the fluid viscosity are separated, and the damper means is configured so that the lever ratio Q is relatively large, and the suspension means By adopting a composite structure in which the elastic means that bears the main stress accompanying the operation is configured so that the lever ratio becomes small, the lever ratio substantially equal to or less than the second predetermined value (0.25) described above (for example, 0) .1) can be constructed. In other words, the center line of the expansion / contraction moving part of the elastic means installed between the body frame and the swing arm or an extension line thereof is located near the swing arm fulcrum between the swing arm fulcrum and the vehicle body center of gravity. It can be configured to be suitable. Therefore, considering the configuration using the shock absorber having the above-described structure , “... the center line of the expansion / contraction moving portion of the shock absorber or its extension line is configured to pass through the vehicle body center of gravity or the vicinity thereof in a side view. The definition of “is ...” is sufficient.

[Summary]
As described above, the gist of the present invention is that the rear wheel suspension shock absorber CU laid across the vehicle body frame F and the swing arm 12 is a vector that is the center line of the telescopic movement portion or the extension line thereof. The line X is provided in the vicinity of the vehicle body center of gravity G, preferably between the vehicle body center of gravity G and the swing arm fulcrum P. This makes it possible to provide a link mechanism between the rear wheel and the oscillating arm fulcrum, while making the rear wheel suspension performance better or better than before, and the expansion / contraction movement amount (stroke) of the shock absorber. In order to ensure, it is not necessary to lengthen the swing arm length, and the position of the swing arm fulcrum can be moved backward as compared with the prior art. Therefore, the engine position can be moved rearward more easily than before, the tendency of front weight is eliminated, and the effect of facilitating steering operation with excellent front-rear weight balance can be exhibited. This effect can be obtained regardless of whether the engine is upright or overturned.

For example, when remodeling a conventional two-suspension TR car ( Reference Examples 2 and 3 ), the position of the shock absorber is moved closer to the engine and the mass is concentrated to improve the rear wheel suspension performance. There is also an advantage that maneuverability is improved. This accompanying effect can be obtained with one shock absorber (monosus structure) or two shock absorbers (double suspension structure). Further, since the relative moment of inertia with respect to the swing arm fulcrum P of the vehicle body caused by the suspension of the rear wheel 2 can be greatly reduced, the conventional two-suspension vehicle as well as the conventional two-suspension vehicle, as well as the conventional mono-suspension vehicle. There is also an advantage that the rear wheel suspension performance can be improved. That is, it can be said that the number of shock absorbers CU is important, not the number of shock absorbers CU.

  A configuration (Examples 1 to 4) in which a lodging type or horizontal type engine, in particular, a four-cycle engine with a relatively large displacement (125 to 250 cc) is mounted (Embodiments 1 to 4) moves the oscillating arm fulcrum to the rear side. It becomes possible. In a TR car with a wheelbase of 1300-1350mm and front and rear tire sizes equivalent to 2.75-21, 4.00-18, a lying or horizontal mission case in a limited effective space between the front and rear wheels This is because, in order to mount the attached engine, a configuration in which the swing arm fulcrum P is provided immediately before the rear wheel 2 as in the present invention is required. This is because the swing arm fulcrum is moved relatively far from the rear wheel in order to place a single shock absorber in front of the rear wheel in a state where a certain amount of expansion and contraction movement is ensured regardless of the presence or absence of the link mechanism. This is a configuration that cannot be adopted in a conventional rear wheel suspension device for a motorcycle that is indispensable to be provided at a certain position (lengthening the swing arm length). In other words, if it is a 4-cycle engine with a small displacement of 50 to 90 cc, etc., it may be possible to install it as a fallen or horizontal engine on a conventional TR car, but it can be used on a general public road with agility. In order to mount an engine with a displacement (125-250cc or more) that exhibits a certain level of torque and horsepower that can be used in trial competitions, as an overturning or horizontal type, as described above A configuration is required in which the swing arm fulcrum is moved rearward to increase the effective space between the front and rear wheels.

  In addition, the use of a lodging or horizontal engine allows the position of a fuel supply device such as a carburetor to be lowered more easily than with an upright engine, and fuel such as gasoline is supplied to the fuel supply device by gravity. In the case of adopting a general fuel supply structure, the bottom position of the fuel tank can be lowered without difficulty. In this way, in addition to lowering the center of gravity and increasing the minimum ground clearance by adopting an overturned or horizontal engine, the tank capacity can be increased without increasing the position of the fuel tank, and thereby lowering the center of gravity. Is also possible. The increase in the fuel tank capacity that can extend the cruising distance without oiling has a great practical advantage in TR cars and on-off cars that often run in areas with few or no gas stations, such as forest roads and mountain driving.

In addition, the rear wheel suspension structure according to the present invention can be applied by modifying the configuration of the current motorcycle, and specifications for dramatically improving the rear wheel suspension performance without replacing with a new vehicle adopting a monosus structure. Can be obtained relatively inexpensively. That is, as shown in Reference Examples 2 and 3 and Examples 4 and 5 , by changing the body frame and auxiliary equipment, changing the shock absorber, etc., the conventional TR car, trail car, on / off The rear-wheel suspension performance of a two-suspension motorcycle such as a car can be greatly improved.

[Another Example]
The transmission mechanism 3 may be a shaft drive structure or a hydraulic drive structure in addition to the chain. Engine E can also be a two-cycle engine. The shock absorber CU arranged immediately above the mission case m has a configuration in which a total of two shock absorbers CU are arranged side by side to reduce the longitudinal length and diameter, a coil spring is provided on either the left and right sides, and a damper is provided on the other side. It is good also as a structure. In addition to the carburetor, the fuel supply device 8 may be an electronically controlled fuel supply device or other means. In the above-described embodiments, the motorcycles to be invented are all described as TR vehicles. However, the present invention is not limited to this and can be applied to motorcycles of on-off vehicles and off-road vehicles .

Left side view of the TR car according to the first embodiment Right side view of the TR car in Fig. 1 External view of the main frame as viewed from the arrow in FIG. Left side view of the semi-competition specification based on the TR car shown in Fig. 1 (Example 2) Left side view of a TR car according to Example 3 External view of the main frame according to arrow B in FIG. Reference Example 3 (FIG. 16) Plan view showing a vehicle body side connection structure of a rear wheel shock absorber for a TR vehicle Reference Example 1 (FIG. 9) Plan view showing a body frame of a TR car Left side view of TR car according to Reference Example 1 Left side view of a TR car according to Reference Example 2 Right side view of the TR car shown in FIG. Left side view of a TR car according to Example 4 The front view which shows the vehicle body side connection structure of the shock absorber for rear wheels in TR car of FIG. The side view which shows another attachment structure of the shock absorber for rear wheels in TR car of FIG. The front view which shows the vehicle body side connection structure of the shock absorber for rear wheels in TR car of FIG. Left side view of TR car according to Reference Example 3 Left side view of TR car according to Example 5 The rear view which shows the principal part of the vehicle body frame in TR car of FIG. The effective space between front and rear wheels is shown, (a) is a conventional monosus TR car, (b) is the monosus TR car of the first embodiment. Comparison diagram that simplifies the configuration where the shock absorber faces the center of gravity and its top and bottom A graph showing the relationship between the lever ratio of the rear wheel suspension and the relative sprung mass

1 Front wheel 2 Rear wheel 2p Axle 3 Transmission mechanism 12 Swing arm
23, 24 Side frame 44 Bracket means 54 First suspension stay 55 Second suspension stay CU Shock absorber E Engine F Body frame P Left-right fulcrum a Piston moving direction line e Engine part m Mission case

Claims (4)

A motorcycle equipped with a transmission case with a transmission case between a front wheel and a rear wheel and equipped with a transmission mechanism for transmitting the driving force of the engine to the rear wheel,
A rear wheel suspension that spans a swing arm that pivotally supports the body frame and supports the rear wheel so that the rear wheel is rotatable and swings about a left and right fulcrum provided at a front end portion. The shock absorber is disposed in a substantially horizontal front-and-back posture directly above the transmission case in a state where there is almost no gap between the transmission case and the transmission case, and directly on the swing arm. And connected
An on-off or off-road type motorcycle in which most of the transmission case is provided at a height position higher than the axis of the rear wheel. The vehicle body frame includes a first suspension stay for bolting a rear portion of the transmission case and a second suspension stay for bolting an engine portion having a cylinder in the engine, and the first suspension stay. 2. The motorcycle according to claim 1 , wherein the shock absorber is connected to bracket means attached to both the first suspension stay and the second suspension stay . The engine is configured such that a cylinder is positioned in front of the transmission case, and a piston moving direction line in the cylinder is horizontal, substantially horizontal, or has a forward tilt angle close to horizontal in a side view. The motorcycle according to 1 . The motorcycle according to claim 3 , wherein a side frame having the left and right fulcrum on which the swing arm is pivoted and a front end portion of the rear wheel are set to have a positional relationship in a side view .

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