Small vehicle

Abstract

To stably turn a small vehicle regardless of a driving technique with a simple and inexpensive configuration.SOLUTION: There is provided a small vehicle 1 in which a pair of right and left front wheels 11 is supported so as to be able to be turned to a vehicle body frame. The small vehicle comprises: a pair of right and left suspension arms 44 which rotatably supports the pair of right and left front wheels; a steering shaft 42 which turns the pair of right and left front wheels following a handle operation; and a power transmission mechanism 51 which receives input of the handle operation force from the steering shaft. The pair of right and left suspension arms is supported in a swingable manner to the vehicle body frame, and the power transmission mechanism transmits the handle operation force to at least one of the pair of right and left suspension arms to make the vehicle body frame inclined around a roll shaft O1.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a small vehicle.

Background Art

[0002] There exists a front two-wheel type three-wheeled vehicle in which the vehicle body can be tilted and turned as a small vehicle. The front two-wheel type three-wheeled vehicle is equipped with a pair of left and right front wheels and a single rear wheel. Although the three-wheeled vehicle is compact and easy to use, it is difficult to ensure stability during turning due to its narrow vehicle width. To solve this problem, it is necessary to tilt the vehicle body in the turning direction like a motorcycle, and various structures such as tilting a pair of left and right front wheels and the rear wheel together with the vehicle body have been proposed (for example, see Patent Document 1). In addition, those equipped with various sensors and actuators for detecting acceleration, tilt, moment, etc. to control the tilt of the vehicle body have also been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the three-wheeled vehicle described in Patent Document 1 has a structure in which the wheels and the vehicle body are tilted by the movement of the center of gravity, and since a certain level of driving skill is required of the driver, it is not suitable for everyone. In addition, those that electrically control the tilt of the vehicle body are costly and the control becomes complicated, so when a malfunction occurs in part, the stability of the entire vehicle decreases.

[0005] In view of this point, the present invention has been made, and it is an object of the present invention to provide a small vehicle that can turn stably with a simple and inexpensive configuration regardless of driving skill.

Means for Solving the Problems

[0006] A small vehicle according to one aspect of the present invention is a small vehicle in which a pair of left and right front wheels are rotatably supported with respect to a vehicle body frame, and includes a pair of left and right suspension arms that rotatably support the pair of left and right front wheels, a steering shaft that steers the pair of left and right front wheels in accordance with a steering operation, and a power transmission mechanism to which a steering operation force is input from the steering shaft. A pair of left and right front suspensions that absorb impacts on the vehicle body frame, It is provided with The power transmission mechanism includes a first bevel gear that rotates integrally with the steering shaft, a second bevel gear that meshes with the first bevel gear and rotates, and a suspension lever that swings about an intermediate portion as the second bevel gear rotates. The pair of left and right suspension arms are swingably supported by the vehicle body frame. The fulcrums of the pair of left and right suspension arms on the vehicle body frame are positioned adjacent to the roll axis. The pair of left and right front suspensions connect both ends of the suspension lever and the pair of left and right suspension arms. Steering operation force is transmitted from the suspension lever to the pair of left and right suspension arms via the pair of left and right front suspensions. The above problems are solved by tilting the vehicle body frame around the roll axis.

Effect of the Invention

[0007] According to the small vehicle of one aspect of the present invention, the steering operation force is transmitted to at least one of the pair of left and right suspension arms, but the pair of left and right front wheels are grounded on the road surface and the swinging of the suspension arms is restricted. Therefore, the vehicle body frame is tilted relative to the suspension arms around the roll axis. When the pair of left and right front wheels are steered along with the steering operation and the vehicle body frame is tilted around the roll axis, the driver can turn the vehicle without moving the center of gravity. In addition, since the vehicle body frame is tilted by a mechanical structure, the structure can be simplified and the cost can be reduced. Therefore, the vehicle can be stably turned with a simple and inexpensive configuration regardless of the driving technique.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0009] In a compact vehicle according to one aspect of the present invention, a pair of left and right suspension arms are swingably supported by a vehicle body frame, and a pair of left and right front wheels are rotatably supported by the pair of left and right suspension arms. A pair of left and right front wheels are steered with respect to the vehicle body frame in accordance with a steering operation by a steering shaft. A steering operation force is input from the steering shaft to a power transmission mechanism, and the steering operation force is transmitted from the power transmission mechanism to at least one of the pair of left and right suspension arms. At this time, since the pair of left and right front wheels are grounded on the road surface and the swinging of the suspension arm is restricted, the vehicle body frame is relatively tilted around the roll axis with respect to the suspension arm. Along with the steering of the pair of left and right front wheels according to the steering operation, the vehicle body frame is tilted around the roll axis, and the driver can turn the vehicle without moving the center of gravity. In addition, since the vehicle body frame is tilted by a mechanical structure, the structure can be simplified and the cost can be reduced. Therefore, the vehicle can be stably turned with a simple and inexpensive configuration regardless of the driving technique.

Examples

[0010] <First Embodiment> Hereinafter, with reference to the accompanying drawings, the small vehicle of the first embodiment will be described in detail. FIG. 1 is a perspective view of the small vehicle of the first embodiment. In the following embodiments, a three-wheeled vehicle will be illustrated and described as the small vehicle. Also, in the following figures, arrow FR indicates the front of the vehicle, arrow RE indicates the rear of the vehicle, arrow L indicates the left side of the vehicle, and arrow R indicates the right side of the vehicle, respectively.

[0011] As shown in FIG. 1, the small vehicle 1 is a front two-wheel type three-wheeled vehicle with a pair of left and right front wheels 11 and a single rear wheel 12. The vehicle body frame 13 of the small vehicle 1 has a base frame 14 at the bottom of the vehicle, a front frame 15 at the front side of the vehicle body, and a rear frame 16 at the rear side of the vehicle body. The base frame 14 forms the skeleton of the bottom of the vehicle, the front frame 15 forms the skeleton of the front side of the vehicle body, and the rear frame 16 forms the skeleton of the rear side of the vehicle body. Various exterior parts such as a cowl and a cover (not shown) are attached to the base frame 14, the front frame 15, and the rear frame 16.

[0012] The base frame 14 is formed by a pair of left and right main pipes 21 extending in the vehicle front-rear direction, a pair of left and right side pipes 22 outside the vehicle width direction of the pair of left and right main pipes 21, and a plurality of bridge pipes 23 connecting these pipes. The front frame 15 is formed in a box shape by a pipe material, a plate material, or the like. A pair of left and right suspension arms 44 are swingably supported below the front frame 15. Each suspension arm 44 extends outward in the vehicle width direction, and a pair of left and right front wheels 11 are rotatably supported at the tip of each suspension arm 44.

[0013] A steering frame 41 is provided at the upper part of the front frame 15, and a steering shaft 42 is supported by the steering frame 41 so as to be steerable. A handle 43 is attached to the upper part of the steering shaft 42, and a steering rod (not shown) is connected to the lower part of the steering shaft 42. The steering rod is moved by the handle operating force to steer each front wheel 11. A suspension lever 56 is supported in a swingable manner in front of the steering frame 41, and suspension arms 44 are connected to both ends of the suspension lever 56 via front suspensions 45.

[0014] The rear frame 16 is formed by a pair of left and right rear pipes 25 that rise obliquely rearward from the rear end of the main pipe 21 and a plurality of bridge pipes 26 that connect the pair of left and right rear pipes 25. An outrigger 27 for preventing tipping is provided on each rear pipe 25. A pair of left and right seat pipes 28 extend horizontally from the middle part in the height direction of the pair of left and right rear pipes 25 toward the front frame 15. A plate-shaped seat 29 is provided on each seat pipe 28, and a saddle-type driver's seat is formed on the base frame 14. A storage space for a fuel tank (not shown) and the like is secured below the seat 29.

[0015] An engine 32 is supported by a suspension bracket 31 at the rear part of the base frame 14 so as to be swingable. As the engine 32, a unit swing engine in which a cylinder assembly 34 is arranged on the front surface of a crankcase 33 is used. The left side of the crankcase 33 extends rearward, and a rear wheel 12 is rotatably supported at the rear end of the crankcase 33. A CVT cover 35 is attached to the open left side surface of the crankcase 33. A belt-type continuously variable transmission (not shown) is housed inside the CVT cover 35, and the driving force of the engine 32 is transmitted to the rear wheel 12 via a belt.

[0016] A magnet cover 36 is attached to the open right side surface of the crankcase 33. A magnet is housed inside the magnet cover 36, and the magnet supplies an ignition voltage to the ignition device. The cylinder axial direction of the cylinder assembly 34 is oriented substantially in the front-rear direction, and the crankcase 33 connected to the cylinder assembly 34 is arranged substantially horizontally to achieve a lower center of gravity of the engine 32. A rear frame 16 is positioned above the engine 32, and a rear end portion on the left side of the crankcase 33 is connected to a part of the bridge pipe 26 of the rear frame 16 via a rear suspension 37.

[0017] In such a small vehicle, since the vehicle width is narrow, it is desired to ensure stability during turning. In a general small vehicle, a structure for tilting the vehicle body and the front and rear wheels is adopted. However, like a motorcycle, the vehicle body and the front and rear wheels have to be tilted by shifting the center of gravity, and a certain level of driving skill is required of the driver. When the small vehicle is a front two-wheel type three-wheeler, the roll axis on the front wheel side is on the vehicle body, and the roll axis on the rear wheel side is at the grounding point between the rear wheel and the ground. Therefore, if the roll axes on the front wheel side and the rear wheel side are too far apart in the vertical direction, it is difficult to operate with a natural feeling when the vehicle turns.

[0018] Also, in a structure where the front wheels are tilted, the scrub radius changes significantly due to the tilt of the front wheels during turning. The scrub radius during turning is different from that during straight running, resulting in different operating feelings during turning and straight running. Also, the scrub radii of the inner and outer wheels of a pair of left and right front wheels are different, and the operating feeling changes with respect to the tilt angle of the vehicle and input changes from the road surface, reducing the operability. Furthermore, if the vehicle body is tilted significantly, the vehicle body may not be able to stand on its own when parking. For this reason, a structure for making the vehicle body stand on its own when parking must be provided for the small vehicle.

[0019] Therefore, the small vehicle 1 of the first embodiment is provided with a power transmission mechanism 51 that transmits the steering operation force input from the steering shaft 42 to a pair of left and right suspension arms 44. When the steering operation force is transmitted to the suspension arm 44, the vehicle body is tilted relative to the suspension arm 44 around the roll axis. When the pair of left and right front wheels 11 are steered by the steering operation, the tilting of the vehicle body around the roll axis is interlocked with the steering of the front wheels 11 via the power transmission mechanism 51. Such a mechanical structure solves various problems peculiar to the small vehicle described above.

[0020] Hereinafter, with reference to FIGS. 2 to 4, the power transmission mechanism of the first embodiment will be described. FIG. 2 is a front view of the small vehicle of the first embodiment. FIG. 3 is a cross-sectional view of the small vehicle in FIG. 2 taken along line A-A. FIG. 4 is a cross-sectional view of the small vehicle in FIG. 3 taken along line B-B.

[0021] As shown in FIGS. 2 and 3, the steering shaft 42 is supported by the front frame 15. The steering shaft 42 is arranged so as to tilt rearward through the center of the vehicle. As described above, the steering wheel 43 is provided at the upper part of the steering shaft 42, and the pair of left and right front wheels 11 are connected to the lower part of the steering shaft 42 via a pair of left and right steering rods (not shown). A pair of front and rear support plates 46 having a U-shaped cross section are provided at the lower part of the front frame 15. A pair of left and right suspension arms 44 are swingably supported by the pair of front and rear support plates 46.

[0022] The proximal end side of the suspension arm 44 is bifurcated, and the bifurcated portions of the proximal end side of the suspension arm 44 are respectively supported by a pair of front and rear support plates 46. A joint 47 is fixed to the distal end side of the suspension arm 44, and the front wheel 11 is supported on the kingpin 48 of the joint 47 via a knuckle 49. Since the kingpin 48 extends substantially vertically, the knuckle 49 swings only in the left - right direction. A steering rod is connected to the knuckle 49, and when the steering rod is moved by a handle operation, the front wheel 11 fixed to the knuckle 49 is steered with the kingpin 48 as a fulcrum.

[0023] As shown in FIGS. 2 to 4, a power transmission mechanism 51 for transmitting the handle operating force to a pair of left - and - right suspension arms 44 is provided on the front frame 15. The power transmission mechanism 51 forms a power transmission path by a first bevel gear 52, a second bevel gear 53, a transmission lever 54, a transmission rod 55, and a suspension lever 56. The first bevel gear 52 is fixed to the lower part of the steering shaft 42, and the first bevel gear 52 rotates integrally with the steering shaft 42. The second bevel gear 53 meshes with the first bevel gear 52 and rotates, and the handle operating force is transmitted from the first bevel gear 52 to the second bevel gear 53.

[0024] A shaft support portion 57 is provided on the front frame 15, and a transmission shaft 58 is rotatably supported by the shaft support portion 57. The proximal end portion of the transmission lever 54 is fixed to the transmission shaft 58 together with the second bevel gear 53. The rotation of the second bevel gear 53 causes the transmission lever 54 to swing via the transmission shaft 58, and the handle operating force is transmitted from the second bevel gear 53 to the transmission lever 54. The transmission lever 54 extends leftward from the transmission shaft 58, and the lower end portion of the transmission rod 55 is connected to the tip end portion of the transmission lever 54. The transmission rod 55 extends vertically, and the suspension lever 56 is connected to the upper end portion of the transmission rod 55.

[0025] The middle part of the suspension lever 56 is swingably supported by the front frame 15. The transmission lever 54 and the suspension lever 56 are connected via the transmission rod 55. The suspension lever 56 swings about the middle part together with the transmission lever 54, and the steering operation force is transmitted from the transmission lever 54 to the suspension lever 56. A pair of left and right front suspensions 45 for absorbing the impact on the vehicle body frame 13 are suspended at both ends of the suspension lever 56. A pair of left and right suspension arms 44 are connected to both ends of the suspension lever 56 by the pair of left and right front suspensions 45, and the steering operation force is transmitted from the suspension lever 56 to the pair of left and right suspension arms 44.

[0026] In the power transmission mechanism 51, when one end of the suspension lever 56 is swung upward and the other end of the suspension lever 56 is swung downward by the steering operation. The steering operation force acts on one side suspension arm 44 in the pulling-up direction by one side front suspension 45, and the steering operation force acts on the other side suspension arm 44 in the pushing-down direction by the other side front suspension 45. At this time, the steering operation force on the pair of left and right suspension arms 44 acts on the vehicle body frame 13, and the vehicle body frame 13 is tilted around the roll axis O1 with the lower part of the front frame 15 as the center.

[0027] Referring to FIGS. 5 to 7, the change in the posture of the vehicle body during turning will be described. FIG. 5 is a front view showing the posture of the vehicle body of the small vehicle according to the first embodiment during straight running. FIG. 6 is a front view showing the posture of the vehicle body of the small vehicle according to the first embodiment during left turning. FIG. 7 is a front view showing the posture of the vehicle body of the small vehicle according to the first embodiment during right turning. In the following description, the pair of left and right members are denoted by the symbols L and R, but the symbols L and R may be omitted when not specifying any member. In FIGS. 6 and 7, although the front wheels are actually steered, for the sake of convenience of explanation, the state where the front wheels are not steered is illustrated.

[0028] As shown in Fig. 5, when the small vehicle 1 is moving straight, the steering wheel 43 (see Fig. 2) is maintained in the neutral position. No steering operation force is input to the steering shaft 42, and no steering operation force is transmitted to the suspension arms 44L and 44R via the power transmission mechanism 51. As described above, the suspension arms 44L and 44R are supported by a pair of front and rear support plates 46, and the vehicle body frame 13 is tilted with the support points of the suspension arms 44L and 44R as the fulcrums 62L and 62R. That is, on the center line C of the vehicle body frame 13, the intermediate position between the fulcrums 62L and 62R of the suspension arms 44L and 44R is the roll axis O1.

[0029] At this time, the center lines L1 and L2 of the front wheels 11L and 11R are slightly inclined inward in the vehicle width direction with respect to the perpendicular Z of the road surface 61, but the inclination of the front wheels 11L and 11R is set so that the scrub radius of the front wheels 11L and 11R becomes substantially zero. That is, the contact points P1 and P2 of the front wheels 11L and 11R with respect to the road surface 61 and the intersection points P3 and P4 of the kingpin extension lines (steering center lines) L3 and L4 with respect to the road surface 61 substantially coincide. Therefore, the front wheels 11L and 11R are less affected by the road surface 61, and it is possible to drive stably without the steering wheel 43 (see Fig. 2) being taken by the kickback from the road surface 61.

[0030] As shown in Fig. 6, when the small vehicle 1 is turning left, the steering wheel 43 is operated to the left, and the steering operation force is transmitted to the suspension arms 44L and 44R via the power transmission mechanism 51. More specifically, when a left-handed steering operation force is input to the steering shaft 42, the first bevel gear 52 integrated with the steering shaft 42 is rotated counterclockwise. The first bevel gear 52 rotates the second bevel gear 53, and as the second bevel gear 53 rotates, the transmission lever 54 is swung upward. The left end side of the suspension lever 56 is pushed up via the transmission rod 55 by the swing of the transmission lever 54.

[0031] The left end of the suspension lever 56 swings upward, causing the front suspension 45L to rise slightly. The front suspension 45L applies a steering operation force to the tip of the suspension arm 44L in the upward pulling direction. The front wheel 11L is attached to the tip of the suspension arm 44L, and the upward pull of the suspension arm 44L is restricted by the weight of the front wheel 11L. Therefore, a reaction force that pulls the center line C of the vehicle body frame 13 toward the suspension arm 44L, that is, a reaction force that tilts the vehicle body frame 13 to the left, acts on the vehicle body frame 13.

[0032] On the other hand, the right end of the suspension lever 56 swings downward, causing the front suspension 45R to be tilted down slightly. The front suspension 45R applies a steering operation force to the tip of the suspension arm 44R in the downward pushing direction. The front wheel 11R is attached to the tip of the suspension arm 44R, and the downward push of the suspension arm 44R is restricted by the grounding of the front wheel 11R. Therefore, a reaction force that pushes the center line C of the vehicle body frame 13 away from the suspension arm 44R, that is, a reaction force that tilts the vehicle body frame 13 to the left, acts on the vehicle body frame 13.

[0033] Due to the reaction force acting on the vehicle body frame 13, the vehicle body frame 13 is tilted to the left about the roll axis O1 with respect to the suspension arms 44L and 44R. When the small vehicle 1 makes a left turn, the driver can tilt the vehicle body frame 13 to the left in accordance with the steering of the front wheels 11L and 11R without shifting the center of gravity to the left. Also, the roll axis O1 of the front wheels 11L and 11R is located at the height of the suspension arms 44L and 44R, and the roll axis O2 of the rear wheels 12 is located at the height of the road surface 61. The difference in height between the roll axis O1 of the front wheels 11L and 11R and the roll axis O2 of the rear wheels 12 is small, making it easier to operate with a natural feeling.

[0034] At this time, the fulcrums 62L and 62R of the suspension arms 44L and 44R are provided adjacent to the roll axis O1, and the swing amounts of the suspension arms 44L and 44R are small. When the compact vehicle 1 is going straight and turning left, the changes in the inclination of the front wheels 11L and 11R are small, and the changes in the scrub radius S of each of the front wheels 11L and 11R are suppressed. Also, the inclinations of the front wheels 11L and 11R are substantially the same, and the difference in the scrub radius S between the inner wheel and the outer wheel is also suppressed. The front wheels 11L and 11R can be turned left without being tilted, and natural handling and running stability can be obtained. The contact ground surface of the front wheels 11L and 11R can be enlarged to ensure good grip force and braking force.

[0035] As shown in FIG. 7, when the compact vehicle 1 makes a right turn, the steering wheel 43 is operated to the right, and the steering operation force is transmitted to the suspension arms 44L and 44R via the power transmission mechanism 51. More specifically, when a clockwise steering operation force is input to the steering shaft 42, the first bevel gear 52 integrally with the steering shaft 42 is rotated clockwise. The first bevel gear 52 rotates the second bevel gear 53, and as the second bevel gear 53 rotates, the transmission lever 54 swings downward. The left end side of the suspension lever 56 is pulled down via the transmission rod 55 by the swing of the transmission lever 54.

[0036] The left end portion of the suspension lever 56 swings downward, and the front suspension 45L is tilted a little. The steering operation force acts on the tip of the suspension arm 44L in the pushing-down direction by the front suspension 45L. The front wheel 11L is attached to the tip of the suspension arm 44L, and the pushing-down of the suspension arm 44L is restricted by the grounding of the front wheel 11L. For this reason, a reaction force that pushes back the center line C of the vehicle body frame 13 from the suspension arm 44L, that is, a reaction force that tilts the vehicle body frame 13 to the right acts on the vehicle body frame 13.

[0037] On the one hand, the right end of the suspension lever 56 swings upward, causing the front suspension 45R to rise slightly. The front suspension 45R applies a steering operation force to the tip of the suspension arm 44R in the upward direction. The front wheel 11R is attached to the tip of the suspension arm 44R, and the upward pull of the suspension arm 44R is restricted by the weight of the front wheel 11R. For this reason, a reaction force that pulls the center line C of the vehicle body frame 13 toward the suspension arm 44R, that is, a reaction force that tilts the vehicle body frame 13 to the right, acts on the vehicle body frame 13.

[0038] Due to the reaction force acting on the vehicle body frame 13, the vehicle body frame 13 is tilted to the right about the roll axis O1 with respect to the suspension arms 44L and 44R. When the small vehicle 1 turns right, the driver can tilt the vehicle body frame 13 to the right in accordance with the steering of the front wheels 11L and 11R without shifting the center of gravity to the right. Further, the roll axis O1 of the front wheels 11L and 11R is located at the height of the suspension arms 44L and 44R, and the roll axis O2 of the rear wheels 12 is located at the height of the road surface 61. The difference in height between the roll axis O1 of the front wheels 11L and 11R and the roll axis O2 of the rear wheels 12 is small, making it easy to operate with a natural feeling.

[0039] At this time, the fulcrums 62L and 62R of the suspension arms 44L and 44R are provided adjacent to the roll axis O1, and the swing amount of the suspension arms 44L and 44R is small. When the small vehicle 1 is going straight and turning right, the change in the inclination of the front wheels 11L and 11R is small, and the change in the scrub radius S of each of the front wheels 11L and 11R is suppressed. Further, the inclinations of the front wheels 11L and 11R are substantially the same, and the difference in the scrub radius S between the inner wheel and the outer wheel is also suppressed. It becomes possible to turn right without tilting the front wheels 11L and 11R, and natural handling and running stability are obtained. The contact surface of the front wheels 11L and 11R can be enlarged to ensure good grip force and braking force.

[0040] Further, the steering shaft 42 is mechanically connected to the suspension arms 44L and 44R via a power transmission mechanism 51. Therefore, when parking, by returning the steering wheel 43 (see FIG. 2) to the neutral position, the vehicle body frame 13 can be changed from an inclined posture to an upright posture, and the small vehicle 1 can be made self-supporting. Further, even when the vehicle is parked with the steering wheel 43 turned, since the inclination of the front wheels 11L and 11R is small, the small vehicle 1 can be made self-supporting while maintaining the inclined posture. Therefore, it is not necessary to provide the small vehicle 1 with a structure for making the vehicle body self-supporting when parking, and the structure of the small vehicle 1 can be simplified.

[0041] As described above, according to the first embodiment, the steering operation force is transmitted to at least one of the pair of left and right suspension arms 44, but the pair of left and right front wheels 11 are grounded on the road surface 61, and the swinging of the suspension arm 44 is restricted. For this reason, the vehicle body frame 13 is tilted relative to the suspension arm 44 about the roll axis O1. As the pair of left and right front wheels 11 are steered along with the steering operation, the vehicle body frame 13 is tilted about the roll axis O1, and the driver can turn the vehicle without moving the center of gravity. Further, since the vehicle body frame 13 is tilted by a mechanical structure, the structure can be simplified and the cost can be reduced. Therefore, with a simple and inexpensive configuration, the vehicle can be stably turned regardless of the driving technique.

[0042] <Second Embodiment> Referring to FIGS. 8 and 9, the small vehicle of the second embodiment will be described. FIG. 8 is a front view of the small vehicle of the second embodiment. FIG. 9 is a cross-sectional view of the small vehicle of FIG. 8 taken along the line C-C. The small vehicle of the second embodiment is different from the small vehicle of the first embodiment in that the suspension lever is directly supported by the transmission shaft. Therefore, regarding the configuration similar to that of the first embodiment in the second embodiment, the description will be omitted as much as possible.

[0043] As shown in FIGS. 8 and 9, a steering shaft 74 is supported by a front frame 72. A handle 75 is provided at the upper part of the steering shaft 74, and a steering plate 76 is provided at the lower part of the steering shaft 74. A pair of front and rear support plates 77 are provided at the lower part of the front frame 72, and the bifurcated base ends of a pair of left and right suspension arms 81 are swingably supported by the pair of front and rear support plates 77. A joint 82 is fixed to the tip side of the suspension arm 81, and a front wheel 73 is supported by a kingpin 83 of the joint 82 via a knuckle 84.

[0044] A power transmission mechanism 91 for transmitting the handle operating force to a pair of left and right suspension arms 81 is provided in the front frame 72. The power transmission mechanism 91 forms a power transmission path by a first bevel gear 92, a second bevel gear 93, and a suspension lever 94. The first bevel gear 92 is fixed to the lower part of the steering shaft 74. A shaft support portion 95 is provided in the front frame 72, and a transmission shaft 96 is rotatably supported by the shaft support portion 95. The second bevel gear 93 and an intermediate portion of a suspension lever 94 having a substantially V shape in front view are fixed to the transmission shaft 96.

[0045] The first bevel gear 92 rotates integrally with the steering shaft 74, the first bevel gear 92 meshes with the second bevel gear 93 and rotates to swing the suspension lever 94. A pair of left and right suspension arms 81 are connected to both ends of the suspension lever 94 via a pair of left and right front suspensions 85. The handle operating force acts on the pair of left and right suspension arms 81 via the pair of left and right front suspensions 85 due to the swinging of the suspension lever 94. The handle operating force acts on one side suspension arm 81 in the pulling-up direction, and the handle operating force acts on the other side suspension arm 81 in the pushing-down direction.

[0046] At this time, a reaction force acts on the vehicle body frame, and the vehicle body frame is tilted about the roll axis O1 between the pair of left and right suspension arms 81. Further, the lower steering plate 76 of the steering shaft 74 is connected to the knuckle 84 of the front wheel 73 via a steering rod (not shown). When the steering rod is moved by a steering operation, the front wheel 73 fixed to the knuckle 84 with the kingpin 83 as a fulcrum is steered. With such a configuration, even in the compact vehicle 71 of the second embodiment, the same effects as those of the compact vehicle 1 of the first embodiment can be obtained.

[0047] <Third Embodiment> Referring to FIG. 10, the compact vehicle of the third embodiment will be described. FIG. 10 is a perspective view of the power transmission mechanism of the third embodiment. The compact vehicle of the third embodiment is different from the compact vehicle of the first embodiment in that a separate type suspension lever is used. Therefore, for the third embodiment, the description of the same configuration as that of the first embodiment will be omitted as much as possible.

[0048] As shown in FIG. 10, the power transmission mechanism 110 forms a power transmission path by a first bevel gear (not shown), a second bevel gear (not shown), a transmission lever 111, a pair of left and right transmission rods 112, and a pair of left and right suspension levers 113. The intermediate portion of the transmission lever 111 is fixed to the shaft support portion 114 of the front frame 107, and a pair of left and right suspension levers 113 are connected to both ends of the transmission lever 111 via a pair of left and right transmission rods 112. One end of each of the pair of left and right suspension levers 113 is supported by the mounting plate 104 of the front frame 107, and a pair of left and right front suspensions 105 are connected to the other ends of the pair of left and right suspension levers 113.

[0049] When the steering shaft 103 rotates, the transmission lever 111 is swung via the first and second bevel gears. When the suspension lever 113 swings, a steering operation force acts on a pair of left and right suspension arms 106 via a pair of left and right front suspensions 105. A steering operation force acts on one side of the suspension arm 106 in the pulling-up direction, and a steering operation force acts on the other side of the suspension arm 106 in the pushing-down direction, so that a reaction force acts on the vehicle body frame and the vehicle body frame is tilted. With such a configuration, even in the compact vehicle 101 of the third embodiment, the same effects as those of the compact vehicle 1 of the first embodiment can be obtained.

[0050] In the first to third embodiments, the power transmission mechanism is configured to transmit the steering operation force to both of a pair of left and right suspension arms to tilt the vehicle body frame around the roll axis. However, the configuration of the power transmission mechanism is not particularly limited. The power transmission mechanism may be configured to transmit the steering operation force to at least one of a pair of left and right suspension arms to tilt the vehicle body frame around the roll axis.

[0051] In the first to third embodiments, the configuration in which the compact vehicle is a front two-wheel type auto tricycle has been described. However, the compact vehicle is not limited to an auto tricycle. The compact vehicle only needs to be configured such that a pair of left and right front wheels are supported so as to be steerable with respect to the vehicle body frame. For example, the compact vehicle may be provided with a plurality of rear wheels.

[0052] In the first to third embodiments, the configuration in which the compact vehicle is a saddle-riding type vehicle has been described. However, the compact vehicle is not limited to a saddle-riding type vehicle. For example, the compact vehicle may be a vehicle in which a driver and a passenger can ride side by side. Further, the vehicle may be one in which a driver's seat is formed such that the driver can extend his or her legs forward.

[0053] In the first to third embodiments, an engine is used as the prime mover, but a motor may be used as the prime mover. When a motor is used as the prime mover, a swing arm is swingably supported at the rear part of the vehicle body frame, and a rear wheel is rotatably supported at the rear end of the swing arm. The motor may be provided on the vehicle body frame or on the swing arm.

[0054] In the first to third embodiments, a single A-arm is used as the suspension arm, but the type of the suspension arm is not particularly limited. A double wishbone arm may be used as the suspension arm.

[0055] In the first to third embodiments, the shape of the handle is not particularly limited, and a steering wheel or a handlebar may be used as the handle.

[0056] In the first to third embodiments, the connection position between the transmission rod and the suspension lever may be formed so as to be changeable. By changing the connection position between the transmission rod and the suspension lever, the lever ratio is changed and the inclination angle of the vehicle body frame can be adjusted. Also, by disconnecting the connection between the transmission rod and the transmission lever and connecting the suspension lever and the suspension arm via the transmission rod, it is possible to fix the vehicle body frame in an upright state.

[0057] In the first to third embodiments, the inclination of the outrigger may be variable according to the inclination of the vehicle body frame. For example, an outrigger may be attached to a unit swing engine.

[0058] In the first to third embodiments, the fulcrums of the pair of left and right suspension arms are positioned adjacent to the roll axis, but the fulcrums of the pair of left and right suspension arms may be separated from the roll axis.

[0059] In the first embodiment, the transmission lever is connected to the suspension lever via the transmission rod. However, the transmission lever may be connected to the suspension arm via the transmission rod. Even with such a power transmission mechanism, the steering operation force can be transmitted to the suspension arm.

[0060] As described above, the compact vehicle (1) of the present embodiment is a compact vehicle in which a pair of left and right front wheels (11) are rotatably supported with respect to a vehicle body frame (13), and includes a pair of left and right suspension arms (44) that rotatably support the pair of left and right front wheels, a steering shaft (42) that steers the pair of left and right front wheels in accordance with a steering operation, and a power transmission mechanism (51) to which a steering operation force is input from the steering shaft. The pair of left and right suspension arms are swingably supported by the vehicle body frame, and the power transmission mechanism transmits the steering operation force to at least one of the pair of left and right suspension arms to tilt the vehicle body frame around the roll axis. According to this configuration, the steering operation force is transmitted to at least one of the pair of left and right suspension arms, but the pair of left and right front wheels are grounded on the road surface and the swing of the suspension arms is restricted. Therefore, the vehicle body frame is tilted relative to the suspension arm around the roll axis. When the pair of left and right front wheels are steered in accordance with the steering operation and the vehicle body frame is tilted around the roll axis, the driver can turn the vehicle without moving the center of gravity. In addition, since the vehicle body frame is tilted by a mechanical structure, the structure can be simplified and the cost can be reduced. Therefore, the vehicle can be stably turned with a simple and inexpensive configuration regardless of the driving technique.

[0061] In the compact vehicle of the present embodiment, the power transmission mechanism transmits the steering operation force to both of the pair of left and right suspension arms to tilt the vehicle body frame. According to this configuration, the vehicle body frame can be tilted more effectively.

[0062] In the small vehicle of this embodiment, the fulcrums (62L, 62R) of the pair of left and right suspension arms in the vehicle body frame are positioned adjacent to the roll axis (O1). According to this configuration, since the roll axis on the front wheel side is between the pair of left and right suspension arms, the roll axes on the front wheel side and the rear wheel side are brought closer vertically, improving the operating feeling. Further, since the fulcrums of the pair of left and right suspension arms are brought closer to the roll axis, the swing amount of the suspension arms is reduced. When the small vehicle is going straight and turning left, the change in the inclination of each front wheel is small, and the change in the scrub radius of each front wheel is suppressed. Also, the inclinations of the pair of left and right front wheels are substantially the same, and the difference in the scrub radii of the pair of left and right front wheels is also suppressed. It is possible to turn without tilting the front wheels, obtaining natural handling and running stability. The contact area of the front wheels can be increased to ensure good grip force and braking force.

[0063] In the small vehicle of this embodiment, a pair of left and right front suspensions (45) that absorb impacts on the vehicle body frame are provided. The power transmission mechanism includes a first bevel gear (52) that rotates integrally with the steering shaft, a second bevel gear (53) that meshes with the first bevel gear and rotates, and a suspension lever (56) that swings about an intermediate portion as the second bevel gear rotates. The pair of left and right front suspensions connect both ends of the suspension lever to the pair of left and right suspension arms, and the steering operation force is transmitted from the suspension lever to the pair of left and right suspension arms via the pair of left and right front suspensions. According to this configuration, the steering operation force can be transmitted to the suspension arms via the front suspensions.

[0064] Although this embodiment has been described, as another embodiment, those obtained by wholly or partially combining the above-described embodiment and the modified examples may also be used.

[0065] Furthermore, the technology of the present invention is not limited to the above embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea. Moreover, if the technical idea can be realized in another way by technological progress or another derived technology, the method may be used for implementation. Therefore, the scope of the claims covers all embodiments that can be included within the scope of the technical idea.

Explanation of Reference Numerals

[0066] 1, 71, 101: Small vehicle 11, 73, 102: Front wheel 13: Vehicle body frame 42, 74, 103: Steering shaft 44, 81, 106: Suspension arm 45, 85, 105: Front suspension 51, 91, 110: Power transmission mechanism 52, 92: First bevel gear 53, 93: Second bevel gear 56, 94, 113: Suspension lever 62L, 62R: Fulcrum O1: Roll axis

Claims

1. A small vehicle in which a pair of left and right front wheels are supported so as to be steerable with respect to a vehicle body frame, a pair of left and right suspension arms that rotatably support the pair of left and right front wheels, a steering shaft that steers the pair of left and right front wheels in accordance with a steering operation, a power transmission mechanism to which a steering operation force is input from the steering shaft, and a pair of left and right front suspensions that absorb an impact on the vehicle body frame, and the power transmission mechanism includes a first bevel gear that rotates integrally with the steering shaft, a second bevel gear that meshes with and rotates with the first bevel gear, and a suspension lever that swings about an intermediate portion as the second bevel gear rotates, the pair of left and right suspension arms are swingably supported by the vehicle body frame, and a fulcrum of the pair of left and right suspension arms in the vehicle body frame is positioned adjacent to a roll axis, the pair of left and right front suspensions connect both ends of the suspension lever and the pair of left and right suspension arms, and a steering operation force is transmitted from the suspension lever to the pair of left and right suspension arms via the pair of left and right front suspensions to tilt the vehicle body frame about the roll axis. A small vehicle characterized by this.

2. The small vehicle according to claim 1, wherein the power transmission mechanism transmits a steering operation force to both of the pair of left and right suspension arms to tilt the vehicle body frame.

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