Vehicle

A vehicle including a first member rotatably supporting a rear wheel, a second member disposed in front of the first member, and a coupling member disposed between the first member and the second member and fixed to the first member and the second member to support the first member and the second member swingably in a left-right direction about an axial line in a front-rear direction. The coupling member is provided so that a position of the post-swing ground contact point is closer to the axial line than a position of the post-swing ground contact point in the left-right direction before the first member swings, the ground contact point being a center in an area on a surface of the rear wheel in contact with a road surface, the post-swing ground contact point being the ground contact point after the first member swings about the axial line.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage of PCT international application Ser. No. PCT/JP2021/000937 filed on Jan. 14, 2021 which designates the United States, incorporated herein by reference, and which is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-004838, filed on Jan. 16, 2020, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

This invention relates to a vehicle so as to be capable of swinging in a left-right direction.

BACKGROUND ART

As an apparatus of this type, conventionally, a three wheeled vehicle with one front wheel and two rear wheels has been known in which the front wheel is swingably supported with respect to the rear wheels via a swing axis extending in the front-rear direction and diagonally downward (for example, see Patent Literature 1). Also, a three wheeled vehicle with two front wheels and one rear wheel has been known in which the rear wheel is supported at the rear end of the frame, swingably in the left-right direction by using the frame extending in the front-rear direction as a swing axis, according to the operation of the handle (for example, see Patent Literature 2).

CITATION LIST

Patent Literature

DISCL0SURE OF INVENTION

Problems to be Solved by the Invention

However, in the vehicle described in Patent Literature 1, it is difficult to sufficiently improve the turning performance of the vehicle because the rear wheels do not swing. In the vehicle described in Patent Literature 2, when the rear wheel swings, the ground contact point of the rear wheel is shifted from the swing axis in the left-right direction, and there is room for improvement in the turning performance of the vehicle.

Means for Solving Problem

An aspect of the present invention is a vehicle including: a front wheel; a rear wheel; a first member that rotatably supports the rear wheel; a second member disposed in front of the first member; and a coupling member disposed between the first member and the second member and fixed to each of the first member and the second member so as to support the first member and the second member swingably relative to each other in a left-right direction about an axial line extending in a front-rear direction. The coupling member is provided so that in a case where a ground contact point is set to a center in an area on a surface of the rear wheel in contact with a road surface and the ground contact point after the first member swings about the axial line is defined as a post-swing ground contact point, a position in the left-right direction of the post-swing ground contact point is closer to the axial line than a position in the left-right direction of the post-swing ground contact point before the first member swings.

Effect of the Invention

According to the present invention, it is possible to improve a turning performance of a vehicle.

DESCRIPTION OF EMBODIMENT

Hereinafter, embodiments of the present invention will be described with reference toFIGS.1A to16C.FIG.1AandFIG.1Bare perspective views each illustrating an entire configuration of a vehicle (hereinafter, may also be referred to as a swingable vehicle)100according to an embodiment of the present invention, andFIG.2is a plan view. This swingable vehicle is configured as a single-passenger electric vehicle capable of standing by itself in a stopped state. The front side of the vehicle100is not swingable, and thus unsteadiness at a low speed can be suppressed, and a slip rollover can be suppressed. Therefore, it is possible to use the vehicle as personal mobility, by loading baggage onto the front vehicle body that is not swingable. Note that it is possible to use the vehicle as a commercial vehicle for the purpose of carrying various types of baggage.

Hereinafter, for the sake of convenience, a front-rear direction, a left-right direction, and an up-down direction are defined as illustrated in the drawings, and the configuration of each part will be described in accordance with the definition. The front-rear direction is a lengthwise direction of the vehicle100, the left-right direction is a vehicle width direction, and the up-down direction is a gravity direction. When the vehicle100is located on a horizontal plane, the up-down direction corresponds to a height direction of the vehicle100.FIG.1Ais a perspective view of a vehicle100, when viewed from an obliquely right rear side, andFIG.1Bis a perspective view, when viewed from an obliquely right front side.

As illustrated inFIGS.1A,1B, and2, the vehicle100is configured as a three-wheeled vehicle including two front wheels1and one rear wheel2, with the rear wheel2serving as a driving wheel. In addition to the front wheels1and the rear wheel2, the vehicle100mainly includes a frame10, which forms a skeleton of the vehicle100, a cover20, which covers a periphery of the frame10, a handlebar30, which is operated by a user (driver), and a seat3, on which the user is seated. Its entirety is configured to be substantially left-right symmetric. The frame10is made of a high-strength metal, whereas the cover20is made of a resin material. The configuration of the frame10will be described later.

The cover20broadly includes a front cover210extending in the up-down direction below the handlebar30, a floor cover220extending in the front-rear direction on a rear side of the front cover210, and a rear cover230extending obliquely rearward on a rear side of the floor cover220.

The front cover210includes a pair of front and rear covers, that is to say, a front surface cover211and a rear surface cover212, which are configured to sandwich in the front-rear direction the frame10(a front frame14to be described later) extending from the vicinity of the front wheels1to the vicinity of the handlebar30. The front surface cover211and the rear surface cover212both extend in the left-right direction and the up-down direction, and each of them is formed in a substantially rectangular shape as a whole. The front surface cover211and the rear surface cover212are integrally coupled with each other by use of fastening means such as bolts, and thus constitute the front cover210. A light or the like is attached to the front surface cover211, and a drink holder or the like is provided on the rear surface cover212.

The floor cover220includes a pair of upper and lower covers, that is to say, a top surface cover221and a bottom surface cover222, which are configured to sandwich in the up-down direction the frame10(side frames11to be described later) extending in the front-rear direction between the front wheels1and the rear wheel2. The top surface cover221and the bottom surface cover222both extend in the left-right direction and the front-rear direction. A bulging portion223, which bulges upward, is provided at a central portion in the left-right direction of the top surface cover221, and steps224as placement portions, on which a user seated on the seat3places his/her own feet, are respectively provided on both sides in the left-right direction of the bulging portion223. A front end portion of the step224extends obliquely upward so as not to interfere with the front wheel1. The top surface cover221and the bottom surface cover222are integrally coupled with each other by use of fastening means such as bolts, and thus constitute the floor cover220.

The rear cover230is configured to cover the frame10(seat frames12to be described later) extending rearward and obliquely upward toward the seat3. Electric component parts, such as an electric power control unit, are stored inside the rear cover230.

The seat3is located above and on a front side of (on an obliquely upper side of) the rear wheel2, and is formed to be elongated in the front-rear direction so that the width becomes narrower toward the front side. The handlebar30extends in the left-right direction substantially above the front wheels1(strictly, above and slightly on a rear side of the handlebar30). The seat3is a riding support portion for supporting the user's buttocks. The user rides on the vehicle100, while being seated on the seat3, in a posture of holding the handlebar30with both hands and placing both feet on the left and right steps224on the top surface cover221.

A traveling motor4(in-wheel motor) to be driven by the electric power supplied from a battery40(FIG.3) and a brake unit5are accommodated inside the rear wheel2. For example, the traveling motor4is disposed on the left side, and the brake unit5is disposed on the right side. The brake unit5is configured as, for example, a drum brake unit that constitutes a drum brake. The vehicle100travels with the traveling motor4being driven, and braking force is applied by regeneration of the traveling motor4, electromagnetic brake, drum brake activation by manual operation, and the like.

Grips31L and31R to be gripped by the user are respectively provided at both left and right end portions of the handlebar30, and a display unit32, which displays vehicle information such as a remaining battery capacity and a set vehicle speed, is provided between the left and right grips31L and31R. In the vicinity of the grips31L and31R, various switches such as a starter switch for instructing on and off of the main power supply, a traveling forward and rearward changeover switch for instructing switching between traveling forward and rearward, a blinker switch for instructing a left or right turn, a speed setting switch for setting the maximum vehicle speed, and a horn switch for instructing activation of the horn are provided so as to be operable by the user.

Furthermore, in the vicinity of the grips31L and31R, an accelerator lever for inputting a travel instruction, a brake lever for instructing the activation of the brake, and the like are provided so as to be operable by the user.

FIG.3is a side view of the vehicle100illustrating a state in which the seat3, the cover20, and various component parts provided on the handlebar30are removed from the vehicle100, and mainly illustrates a configuration of the frame10. As illustrated inFIG.3, the frame10includes a pair of left and right (only one of them is illustrated) side frames11disposed at a central part in the front-rear direction of the vehicle100, seat frames12disposed on a rear side of the side frames11, a pair of left and right (only one of them is illustrated) swing arms13extending in the front-rear direction below the seat frames12, and a front frame14extending upward from a front end portion of the side frames11, and the entire frame is formed to be left-right symmetric.

The left and right side frames11are each formed of, for example, a pipe member having a substantially circular cross-section. The left and right side frames11each include a horizontal portion111extending substantially horizontally in the front-rear direction, a front inclined portion112bent from a front end portion of the horizontal portion111and extending inward in the left-right direction and obliquely upward, and a coupling portion113extending in the left-right direction and coupling rear end portions of the left and right horizontal portions111. A bracket141is provided on a lower end portion of the front frame14so as to protrude rearward, and front end portions of the left and right front inclined portions112are respectively fixed to left and right side surfaces of the bracket141by welding or the like.

The vehicle100is provided with a battery accommodation portion15. The battery40has a predetermined length, width, and height, and is formed in a substantially rectangular parallelepiped shape as a whole. The battery40is accommodated in the battery accommodation portion15, which is a space between the left and right side frames11, more specifically, an accommodation space on an inner side of the left and right horizontal portions111. Specifically, the battery40is accommodated to be laid down as illustrated.

The battery accommodation portion15includes a holder151, which surrounds the battery40, and a support frame115, which supports the battery40via the holder151. The support frame115is formed in a substantially letter U shape, when viewed from the front side, and both left and right end portions of the support frame115are respectively fixed to the horizontal portions111of the left and right side frames11.

Although not illustrated, the holder151is supported by the side frame11to be capable of turning in the up-down direction. The battery40is in a horizontal posture as illustrated at the time of traveling. However, at the time of attachment or detachment, the holder151is turned and the battery40is to be in an inclined posture with an upward gradient toward the front side.

The seat frames12include, for example, a pair of left and right pipe members each having a substantially circular cross-section. The seat frames12extend obliquely upward from their front end portion toward the rear side, are bent forward and inward in the left-right direction above the rear wheel2(above the rotation center), and are then integrally connected through a connection portion121. The seat3is attached onto an upper side of the connection portion121of the seat frames12. Brackets123are respectively fixed to lower end portions of left and right seat frames12. As illustrated inFIGS.1A and1B, a guide126as an occupant support portion for supporting the user's buttocks and lumbar part is attached on a rear side of the seat3.

Front end portions of the left and right swing arms13are pivotally supported onto the brackets123so as to be respectively pivotable with a pair of left and right pivot shafts131extending in the left-right direction, as fulcrums. Rear end portions of the left and right swing arms13are rotatably connected with both end portions in the left-right direction of the rotation shaft of the rear wheel2. Impact absorbing units16each having a coil spring or the like are interposed respectively between the left and right seat frames12and between the left and right swing arms13.

A lower end portion of the front frame14is fixed to the bracket141, and the front frame14extends upward and rearward (obliquely rearward) from the lower end portion. At the lower end portion of the front frame14, a support frame is provided to protrude in the left-right direction, and the left and right front wheels1are rotatably supported by the support frame. The front frame14is formed in a pipe shape, and a steering shaft33is rotatably inserted into the front frame14. A stem34is attached onto an upper end portion of the steering shaft33with a bolt. The stem34is bent upward and forward in a substantially letter L shape in a side view, and the handlebar30is fixed to the steering shaft33through the stem34. When the handlebar30is operated to turn to the left or right, its operation force is transmitted through a tie rod, a knuckle, a king pin, and the like, which are not illustrated, to the left and right front wheels1. Accordingly, the left and right front wheels1are steered, and the vehicle100can be made to turn to the left or right.

As a characteristic configuration in the present embodiment, a swing joint50is disposed between the side frames11and the swing arms13for supporting the rear wheel2and between the side frames11and the seat frames12. The side frames11, the seat frames12, and the swing arms13are coupled through the swing joint50. Specifically, rear end portions of the side frames11, and front end portions of the seat frames12and the swing arms13are respectively fixed to a front end portion and a rear end portion of the swing joint50. The rear end portion of the swing joint50is configured to be rotatable about an axial line La with respect to the front end portion, so that the rear wheel2side is capable of swinging in the left-right direction with respect to the side frames11. Hereinafter, the side frames11and the like on the front side of the swing joint50will be referred to as a front vehicle body, whereas the seat frames12, the swing arms13, and the like on the rear side of the swing joint50will be referred to as a rear vehicle body, in some cases.

The swing joint50extends in the front-rear direction along a center line (vehicle center line) passing through the center in the left-right direction of the vehicle100. More specifically, an axial line La passing through the center of the swing joint50(a shaft portion52to be described later), that is, a swing axis extends in the front-rear direction along the vehicle center line with a downward gradient toward the rear side.FIG.3is a view illustrating a state before the rear wheel2swings, and an intersection of a perpendicular line L0drawn from a rotation center P1of the rear wheel2to a road surface S1and the road surface Si is a ground contact point P2before swinging. An intersection Pa of the axial line La and the perpendicular line L0is located above the ground contact point P2and below the rotation center P1. The configuration of the swing joint50will be described later. The pair of left and right front wheels1are not swingable. Therefore, the vehicle100is capable of standing by itself, when stopped, and it is possible to suppress a slip-induced rollover of the front wheels on a slippery road surface. In addition, the unsteadiness of the vehicle100during low-speed traveling is suppressed, and the stability of the vehicle100is high.

FIG.4is a perspective view of the vehicle100, when viewed obliquely from below. As illustrated inFIG.4, the left and right swing arms13are coupled integrally with each other through a coupling frame132in a pipe shape extending in the left-right direction on a front side of the rear wheel2. A coupling frame122in a pipe shape extending in the left-right direction is provided above the coupling frame132(seeFIG.5), and the left and right seat frames12are coupled integrally with each other through the coupling frame122. The left and right brackets123on a front side of the coupling frame132are coupled integrally with each other through a coupling plate17in a substantially rectangular shape that extends in the left-right direction. The coupling plate17is provided to be inclined rearward and downward along the axial line La, and the rear end portion of the swing joint50is attached to a front end portion of the coupling plate17. The front side of the swing joint50is disposed above the bottom surface cover222.

FIG.5is a perspective view of a substantial part of the vehicle100(when viewed obliquely from above) illustrating a configuration of component parts around the swing joint50. InFIG.5, illustration of the cover20is omitted for the sake of convenience. As illustrated inFIG.5, the coupling plate17includes a pair of a front pipe portion171and a rear pipe portion172each having a substantially cylindrical shape and extending on an inner side in the left-right direction of the left and right brackets123, a connection portion173, which connects intermediate portions in the left-right direction of the front pipe portion171and the rear pipe portion172, and a pair of left and right plate portions174, which are bridged between the pipe portions171and172on both the left and right sides of the connection portion173. The swing joint50, the coupling plate17, and the like constitute a coupling portion that swingably supports the rear vehicle body with respect to the front vehicle body.

Screw portions171aare respectively provided at both left and right end portions of the front pipe portion171, and bolts133penetrating through the swing arm13and the bracket123are screwed into the screw portion171a. The front pipe portion171and the bolts133constitute the pivot shaft131, which serves as a pivot fulcrum of the swing arm13. An upper end portion of the bracket123is fixed to the seat frame12by welding, for example.

The rear end portions of the left and right side frames11are fixed to the coupling portion113in a substantially plate shape that extends in the left-right direction on a rear side with respect to the battery40, and the left and right side frames11are coupled integrally through the coupling portion113. Floor frames114are respectively fixed to the left and right side frames11. The floor frame114extends in the front-rear direction to protrude outward in the left-right direction from the side frame11, and the step224(FIG.1A) is supported by the floor frame114.

The swing joint50includes a joint case51formed in a substantially box shape, and a shaft portion52extending along the axial line La in the joint case51and protruding from a rear end surface of the joint case51.FIG.6is a cross-sectional view (cross-sectional view taken along line VI-VI inFIG.5) schematically illustrating an internal configuration of the swing joint50. As illustrated inFIG.6, the swing joint50includes a Neidhart damper53in its inside. The Neidhart damper53includes a cam block531in a substantially rhombic shape that is spline-coupled with the shaft portion52, and rubber rollers532disposed to respectively oppose surfaces each formed in a concave shape of the cam block531.

FIG.6illustrates an initial position before torque works on the shaft portion52.

When the torque works on the shaft portion52from this state and the shaft portion52rotates about the axial line La (swing axis) in an arrow A direction inFIG.6, the cam block531also rotates integrally with the shaft portion52. In this situation, the cam block531elastically deforms the rubber rollers532, and the rubber rollers532become elliptical. The rotational resistance to the shaft portion52increases, as the rotation angle increases. When the torque working on the shaft portion52becomes zero, the rubber rollers532return to the original shapes by the elastic force, and the shaft portion52returns to the initial position. Specifically, the rubber rollers532each function as a repulsive member capable of accumulating repulsive force when the shaft portion52rotates (swings) and urging the shaft portion52in a direction of returning the rotation.

As illustrated inFIG.5, a front end portion of the swing joint50, that is, a front end portion of the joint case51is fixed to an upper surface of the coupling portion113with bolts50a. The rear end portion of the swing joint50, that is, a rear end portion of the shaft portion52is fixed to a front end portion of the coupling plate17. With such a configuration of the swing joint50, the rear vehicle body (the seat frames12and the swing arms13) is capable of swinging with respect to the front vehicle body (the side frames11). As illustrated inFIG.2, rear end portions of steps224are located on a rear side with respect to a front end portion of the rear cover230, and gaps are respectively provided in the left-right direction between the rear cover230, which is a part of the rear vehicle body, and the left and right steps224. The gaps are provided so that the steps224do not come into contact with the rear cover230, even when the rear vehicle body swings to the maximum with respect to the front vehicle body. Therefore, swinging is enabled without interference between the rear cover230and the steps224.

FIG.7is a plan view illustrating an operation when the vehicle100makes a turn (for example, turns to the left). At the time of turning to the left, the driver inclines his/her own body to the left while holding the non-swingable handlebar30on the front side of the vehicle and placing his/her own feet on the non-swingable steps224to support his/her own body (holding firmly). Furthermore, the driver steers the handlebar30to finely adjust the turning direction. In this situation, as illustrated inFIG.7, the rear vehicle body swings, the rear wheel2is inclined to the left, and the gravity center position of the vehicle100changes to P11on the left side from P10on a vehicle center line CL0. In this manner, the rear vehicle body on which the user is seated swings, and the gravity center position of the vehicle100during traveling changes to be closer to the center of the turn. Thus, the turning performance can be improved.

The front wheels1face the left direction. Therefore, a leftward slip angle θ11with respect to an advancing direction A1, that is, the slip angle θ11in an identical direction to the turning direction is generated in the front wheels1, and leftward cornering force as indicated by an arrow F1works on the front wheels1. On the other hand, the rear wheel2faces the right direction. Therefore, a rightward slip angle θ12, that is, the slip angle θ12in an opposite direction to the turning direction is generated in the rear wheel2, and rightward cornering force as indicated by an arrow F2works on the rear wheel2. That is, a toe angle opposite to the swing direction is generated in the rear wheel2. Furthermore, a leftward camber thrust caused by the swing, as indicated by an arrow F3, works on the rear wheel2.

FIGS.8A and8Bare rear views of the vehicle100respectively illustrating a state before swinging and a state after swinging of the rear vehicle body (a state before making a turn and a state after making a turn to the left). The position of the axial line La (swing axis) of the swing joint50is unchanged before and after swinging, and passes through the center in the left-right direction (on the vehicle center line CL0) of the vehicle100. Therefore, as illustrated inFIG.8A, a center line CL1passing through the center in the width direction of the rear wheel2before swinging coincides with the axial line La. InFIG.8B, an angle formed by the perpendicular line L0(FIG.3) perpendicular to the road surface S1and the center line CL1, that is, a swing angle θ1is, for example, 15 degrees.

The rear wheel2includes a tire having an arc-shaped cross-section in which a ground contact area hardly changes before and after swinging. Therefore, in the following description, it is assumed that the rear wheel2comes into contact with the road surface Si at a point (ground contact point) instead of a plane. Strictly, the tire elastically deforms and comes into contact with the road surface S1on a plane. However, the ground contact area is narrow in a case where a tire having an arc-shaped cross-section is used. Hence, in the present embodiment, the center of the ground contact area is defined as the ground contact point for the sake of convenience. The ground contact point (pre-swing ground contact point) P2inFIG.8Ais identical to the ground contact point P2inFIG.3.

As illustrated inFIG.8B, when the rear wheel2swings leftward, a point P21on the tire surface on a left side with respect to the pre-swing ground contact point P2becomes a new ground contact point (post-swing ground contact point). On the other hand, the pre-swing ground contact point P2is shifted to a right side with respect to the axial line La, and moves upward from the road surface S1. Note that although the movement of the ground contact point is small, the position of the ground contact point is illustrated in an exaggerated manner inFIGS.8A and8B. As illustrated inFIG.8A, the post-swing ground contact point P21is located above the road surface S1before swinging, and is not in contact with the ground. In other words, at the time of swinging, the post-swing ground contact point P21moves to under the axial line La, as illustrated inFIG.8B. Accordingly, the post-swing ground contact point P21coincides with the position in the left-right direction of the axial line La, when the vehicle100makes a turn, and the turning performance of the vehicle100is improved. In the present embodiment, attention is given to a position change of the post-swing ground contact point P21, which is not in contact with the ground before swinging, but which is in contact with the ground after swinging. Therefore, the post-swing ground contact point P21may be referred to as an attention point. The post-swing ground contact point P21is preferably provided so as to coincide with the axial line La all the time from a swing start to a maximum swing state.

FIG.9is a view for describing settings of the axial line La of the swing joint50, and schematically illustrates the position of the axial line La before swinging. The axial line La in the drawing is identical to that inFIG.3, and axial lines Lb and Lc are comparative examples in the present embodiment. Angles θa, θb, and θc respectively formed by the axial lines La, Lb, and Lc and the horizontal line, that is, the inclination angle increases in the order of the axial lines La, Lb, and Lc (θa<θb<θc). Therefore, respective intersections Pa, Pb, and Pc of the perpendicular line L0drawn from the rotation center P1of the rear wheel2to the road surface S1and the axial lines La, Lb, and Lc are located to be higher in the order of Pc, Pb, and Pa. In particular, the intersection Pa is located to be higher than the ground contact point P2(FIG.8A), the intersection Pb is located at an identical position to the ground contact point P2, and the intersection Pc is located to be lower than the ground contact point P2.

FIGS.10A to10Care plan views each illustrating a position change of the rear wheel2with respect to the axial lines La, Lb, and Lc, in a case where the rear vehicle body is made to swing to the left side when the vehicle100turns to the left, in a similar manner toFIG.8B. P21a, P21b, and P21cin the drawing respectively correspond to the post-swing ground contact point P21inFIG.8B. An intersection P20of the center line CL1in the width direction of the rear wheel2and a center line CL2along the rotation center of the rear wheel2corresponds to a center point indicating the center position of the rear wheel2.

As illustrated inFIG.10A, in the present embodiment, the post-swing ground contact point P21ais located on the axial line La (an identical position to the position in the left-right direction of the axial line La). Therefore, the positions of the ground contact points are identical to each other before and after swinging (both on the axial line La), and the vehicle100is capable of making a turn smoothly in accordance with swinging of the rear vehicle body. On the other hand, as illustrated inFIGS.10B and10C, in the comparative examples of the present embodiment, the post-swing ground contact points P21band P21care respectively shifted to the left side with respect to the axial lines Lband Lc. In this case, the shift amount is larger in the example ofFIG.10Cthan that in the example ofFIG.10B. When the post-swing ground contact points P21band P21care respectively shifted in the left-right direction with respect to the axial lines Lb and Lc in this manner, the position of the ground contact point is shifted from the swing axis (axial lines Lb and Lc) whenever the vehicle100makes a turn. Accordingly, it is difficult to make a turn smoothly.

In addition, as illustrated inFIG.10A, in the present embodiment, a slip angle θ12aof the rear wheel2when the vehicle100makes a turn faces an opposite direction to the turning direction. Therefore, a turning radius of the vehicle100can be made small, and a small-turning performance is improved. As illustrated inFIGS.10A to10C, the slip angles θ12a, θ12b, and θ12cof the rear wheel2when the vehicle100makes a turn are larger, as the inclination angles of the axial lines La, Lb, and Lc (FIG.9) become larger (θ12a<θ12b<θ12c). Therefore, the small-turning performance of the vehicle100is adjustable by appropriately setting the inclination angle.

According to the present embodiment, the following operations and effects are achievable.

(1) The vehicle100includes the front wheels1and the rear wheel2, the rear vehicle body (the seat frames12and the swing arms13) that supports the rear wheel2to be rotatable, the front vehicle body (the side frames11) disposed on a front side of the rear vehicle body, and the swing joint50that is disposed between the rear vehicle body and the front vehicle body, that is fixed to each the rear vehicle body and the front vehicle body, and that supports the rear vehicle body to be swingable in the left-right direction with respect to the front vehicle body about the axial line La extending in the front-rear direction (FIGS.1A,1B, and3). The swing joint50is provided so that the position in the left-right direction of an attention point (the post-swing ground contact point P21), on the surface of the rear wheel2, that constitutes the center of the ground contact area between the rear wheel2and the road surface S1, when the rear vehicle body swings about the axial line La, is closer to the axial line La than the position before the rear vehicle body swings. More specifically, the swing joint50is provided so that the position in left-right direction of the attention point after swinging substantially coincides with the position in left-right direction of the axial line La (FIGS.8A,8B, and10A). In other words, the swing joint50is provided so that in a case where the ground contact point is set to the center of the area on the surface of the rear wheel2in contact with the road surface S1(ground surface), the position in the left-right direction of the post-swing ground contact point P21(FIG.8B), which is a ground contact point when the rear vehicle body swings about the axial line La, is closer to the axial line La than the position in the left-right direction of the post-swing ground contact point P21(FIG.8A) before the rear vehicle body swings.

With this configuration, the ground contact points (the pre-swing ground contact point P2and the post-swing ground contact point P21) are both located below the axial line La, before and after the rear vehicle body swings. Therefore, the ground contact point can be prevented from being shifted in the left-right direction from the axial line La at the time of swinging, and the vehicle100is capable of making a turn smoothly.

(2) The swing joint50is provided such that the intersection Pa of the axial line La and the perpendicular line L0to the road surface S1passing through the rotation center P1of the rear wheel2before the rear vehicle body swings is located to be higher than the road surface S1(FIGS.3and9). Accordingly, the position in the left-right direction of the attention point after swinging (the post-swing ground contact point P21) can be made to coincide with the axial line La.

(3) The axial line La of the swing joint50is provided to be inclined with a downward gradient toward the rear side (FIGS.3and9). Accordingly, the slip angle θ12aof the rear wheel2can be generated in an opposite direction to the turning direction (FIG.10A), and the turning performance of the vehicle100can be improved.

(4) The swing joint50and the rear vehicle body are provided such that when the rear vehicle body swings about the axial line La, the direction of the rear wheel2(direction orthogonal to the rotation shaft of the rear wheel2) is shifted with respect to the front-rear direction (axial line La) that is the advancing direction of the vehicle100(FIG.10A). Accordingly, the small-turning performance of the vehicle100can be easily improved.

(5) The vehicle100further includes the seat3and the guide126, which are coupled with the rear vehicle body to swing integrally with the rear vehicle body, and which supports the user's buttocks or back (FIGS.1A and1B). Accordingly, the rear vehicle body can be easily swung by the weight shift of the user.

(6) The vehicle100further includes the step224provided integrally with the front vehicle body to enable the user's foot to be placed on (FIGS.1A and1B). Accordingly, the user is able to easily swing the rear vehicle body with respect to the front vehicle body while holding his/her own feet firmly.

(7) The axial line La extends in the front-rear direction along the vehicle center line CL0at the center in the left-right direction of the vehicle100(FIGS.3and7). The front wheel1includes two wheels arranged on both sides in the left-right direction of an extension line of the axial line La, and the rear wheel2includes a single wheel arranged at the center in the left-right direction of the vehicle100(FIGS.1A,1B, and7). In such a three-wheeled vehicle including two front wheels and one rear wheel, the rear wheel2side is configured to swing as in the present embodiment, so that the vehicle100is capable of standing by itself when stopped, and it is possible to improve the turning performance, while ensuring the stability of the vehicle100.

The vehicle100in the present embodiment, by the way, is configured to be swingable. Hence, the following drawback may occur, when the vehicle travels on the ground inclined in the vehicle width direction (on a lateral-side inclined surface).FIG.11Ais a rear view of the vehicle100traveling on a lateral-side inclined surface that is inclined at a predetermined angle θa with respect to the horizontal plane. As illustrated inFIG.11A, while the vehicle is traveling on the lateral-side inclined surface, a gravity center position Pα of the vehicle100is shifted in the left-right direction (to a valley side) from a reference line CLα extending in the vertical direction passing through the ground contact point of the rear wheel2. For this reason, a moment due to gravity at the gravity center position Pα works on the rear vehicle body with the ground contact point of the rear wheel2as a fulcrum.

As a result, as illustrated inFIG.11B, the inclination amount of the rear vehicle body increases, and the gravity center position Pα is further shifted in the left-right direction (to the valley side) from the reference line CLα. From this state, in order to make the gravity center position Pα coincide with the reference line CLα as illustrated inFIG.11C, the user has to shift his/her own weight and change the posture. However, the weight shift amount of the user is large in recovering the posture to the state ofFIG.11Cfrom the state ofFIG.11B. Hence, this is a large burden for the user. Such a drawback similarly occurs not only in a case where the vehicle100travels on the lateral-side inclined surface but also in a case where the rear vehicle body is inclined outward in the turning radius direction due to the centrifugal force working on the vehicle100, when the vehicle100makes a turn.

Therefore, in order to restrict swinging of the rear vehicle body during traveling on the lateral-side inclined surface or during traveling while making a turn, in the present embodiment, as will be described in the following, a restricting portion is provided in the coupling portion (swing joint50) that supports the front vehicle body and the rear vehicle body so as to be relatively swingable in the left-right direction.

FIG.12is a perspective view of the swing joint50, when viewed from an obliquely front side. As illustrated inFIG.12, the swing joint50is fixed to the coupling portion113, with which rear end portions (not illustrated) of the left and right side frames11are fit. A restricting portion60is disposed to be adjacent to a front end surface of the swing joint50. More specifically, a circular plate61is fixed to the front end portion of the shaft portion52of the swing joint50, and the circular plate61rotates integrally with the shaft portion52about the axial line La. A gear61a having a predetermined number of teeth Z1(for example, Z1=100) is formed on an outer circumferential surface of the circular plate61. A rotating body62, which is rotatable about an axial line L1parallel to the axial line La, is disposed above the circular plate61.

The rotating body62includes a small-diameter circular plate and a large-diameter circular plate respectively on a front side and a rear side to rotate integrally with each other about the axial line L1. A gear62ahaving a predetermined number of teeth Z2(for example, Z2=20) to mesh with the gear61ais formed on an outer circumferential surface of the small-diameter circular plate. A gear62bhaving a predetermined number of teeth Z3(for example, Z3=50) is formed on an outer circumferential surface of the large-diameter circular plate. A rotating body63, which is rotatable about an axial line L2parallel to the axial line La, is disposed above the rotating body62. The rotating body63includes a small-diameter circular plate631and a large-diameter circular plate632respectively on a front side and a rear side to rotate integrally with each other about the axial line L2(seeFIG.13A). A gear63ahaving a predetermined number of teeth Z4(for example, Z4=20) to mesh with the gear62bis formed on an outer circumferential surface of the small-diameter circular plate631. An engaging portion65, which is engageable with an outer circumferential surface63bof the circular plate, is disposed above the large-diameter circular plate632.

Although not illustrated in detail, the rotating bodies62and63and the engaging portion65are supported via a bracket64. The bracket64is fixed to a bracket113aat a front end portion of the coupling portion113and the joint case51of the swing joint50(for example, an upper end portion of a bolt51a, which protrudes from the joint case51).

FIG.13Ais a front view (a view when viewed from the front side) illustrating a configuration of a substantial part of the restricting portion60, and is a view illustrating an initial state in a case where the vehicle100travels straight on a horizontal road surface. As illustrated inFIG.13A, the engaging portion65includes a sprag651, which is disposed above the rotating body63so as to face an outer circumferential surface63b of the large-diameter circular plate632. A case652is disposed above the sprag651so as to surround an upper portion of the sprag651. In the initial state ofFIG.13A, a gap is provided between the sprag651and the case652, and the sprag651is swingable in the left-right direction about an axial line L3in the front-rear direction. A bottom surface of the sprag651is formed in a gently curved surface shape. Recesses651aare respectively provided on the left and right side surfaces of the sprag651.

Levers653are respectively provided on both left and right sides of the sprag651so as to be pivotable in the up-down direction about an axial line L4parallel to the axial line La. The lever653is formed to be curved upward toward an inner side in the left-right direction. In the initial state, the lever653is located at an initial position that is pivoted upward. In this situation, tip end portions of the levers653are respectively disposed to face the recesses651a, while being spaced apart from the left and right side surfaces of the sprag651. Balls654are respectively mounted on the upper surfaces of the left and right levers653so as to be movable in the left-right direction along upper surfaces of the levers653.

In the initial state, the ball654is located on a base end portion side (outer side in the left-right direction) of the lever653. In this situation, a bottom surface of the sprag651is spaced apart from the outer circumferential surface63bof the large-diameter circular plate632of the rotating body63. Therefore, the rotating body63is rotatable in any of an R1direction and an R2direction inFIG.13A. In the state ofFIG.13A, when the vehicle100travels on, for example, the lateral-side slope as illustrated inFIG.11A, the shaft portion52rotates due to swinging of the rear vehicle body. The rotation of the shaft portion52is transmitted to the rotating body63through the gear61aof the circular plate61, the gears62aand62bof the rotating body62, and the gear63aof the rotating body63.

While traveling on the lateral-side slope, the balls654move leftward by gravity as illustrated inFIG.13B. Therefore, the lever653on the right side pivots downward, the tip end portion of the lever653abuts a right end surface of the sprag651, and pushes downward a right end portion on a lower side of the sprag651. Accordingly, the sprag651swings leftward, and the bottom surface of the sprag651abuts the outer circumferential surface63b of the circular plate632of the rotating body63. As a result, the rotation of the rotating body63in the R1direction is inhibited, and a leftward swing of the rear vehicle body is inhibited.

While traveling on the lateral-side slope, the rotation of the shaft portion52is accelerated at a predetermined speed increase ratio (for example, 12.5) from the ratio of the numbers of teeth of the gears61a,62a,62b, and63a, and is transmitted to the rotating body63. Therefore, the rotation amount of the rotating body63is increased more than the rotation amount of the shaft portion52, and thus the rotation, that is, swinging of the shaft portion52can be suppressed with high sensitivity.

In this manner, while traveling on the lateral-side slope, the rear vehicle body is restricted from swinging leftward, so that the swing amount of the rear vehicle body is suppressed in the state ofFIG.11A. In this situation, the rotation of the rotating body63in the R2direction inFIG.13Bis permitted, and the rear vehicle body is capable of swinging rightward. Accordingly, the user is easily able to recover his/her own posture to the state ofFIG.11C. In a case where the centrifugal force works while the vehicle is traveling and making a turn, the balls654move in the direction of the centrifugal force. Therefore, similarly to the case where the vehicle travels on the lateral-side slope, swinging of the rear vehicle body can be restricted.

FIG.14is a front view (a view when viewed from the front side) illustrating another configuration of the restricting portion. Note that the same parts as those inFIG.12are denoted by the same reference numerals. In the example ofFIG.14, the restricting portion60includes the circular plate61coupled with the front end portion of the shaft portion52, a rotating body621disposed on an upper side of the circular plate61, a rotating body622disposed on an upper side of the rotating body621, and the rotating body66rotatable about the axial line L2. The rotating body621and the rotating body622are respectively rotatable about axial lines L11and L12parallel to the axial line L2. On outer circumferential surfaces of the rotating bodies621and622, gears621aand622aeach including a predetermined number of teeth that mesh with each other are formed. The gear61aof the circular plate61meshes with the gear621a.

The rotating body66includes a small-diameter circular plate661and a pair of front and rear large-diameter circular plates662and663, which rotate integrally with each other about the axial line L2. A gear66ahaving a predetermined number of teeth so as to mesh with the gear622ais formed on an outer circumferential surface of the circular plate661. The circular plates662and663each have a larger diameter than that of the circular plate632inFIG.12, and gears66band66care respectively formed on their outer circumferential surfaces, as illustrated inFIG.15. Each tooth of the gear66bis formed to be inclined in the R1direction, and each tooth of the gear66cis formed to be inclined in the R2direction.

As illustrated inFIG.14, a pair of left and right engaging portions67are respectively provided above the circular plates662and663. The engaging portion67includes a pair of left and right levers671pivotable in the up-down direction, and a pair of left and right balls672, which move in a direction onto which the gravity or centrifugal force works, and push the respective levers671. InFIG.14, the engaging portion67is illustrated in a simplified manner. Although not illustrated, the rotating bodies621,622, and66and the engaging portion67are supported by the coupling portion113and the joint case51via the bracket in a similar manner toFIG.12.

FIG.15is a perspective view illustrating a configuration of a substantial part of the engaging portion67. InFIG.15, illustration of the balls672is omitted. As illustrated inFIG.15, the pair of left and right levers671are pivotally supported via a single shaft portion673extending in the front-rear direction.FIG.15illustrates an initial state before the balls672move in the left-right direction. In this state, claws671aat tip end portions of the left and right levers671are respectively spaced apart from the gears66band66c, and the circular plates662and663are rotatable in the R1direction and the R2direction inFIG.15. The rotating directions of the circular plates662and663are opposite to the rotating direction of the circular plate61. The numbers of teeth of the gears621aand622aare appropriately set so that the torque is transmitted from the circular plate61to the circular plates662and663at a predetermined speed increase ratio.

From this state, for example, the vehicle100travels on a lateral-side slope, and when the balls672move leftward due to gravity, the claw671a of the lever671on the left side is engaged with the gear66b. Accordingly, the rotation of the rotating body66in the R2direction is inhibited, and swinging of the rear vehicle body can be restricted. In this situation, the rotation of the rotating body66in the R1direction is permitted, so that the user is easily able to recover his/her own posture.

The levers671may extend in a substantially arc shape along the outer circumferential surface of the circular plates662and663so that the tip end portions of the levers671are located to be slightly lower than the axial line L2, and weights may be provided at the tip end portions of the levers671. In this case, the circular plates662and663are configured to rotate in an identical direction to the circular plate61. For example, the rotating body622is omitted, and the gear621aof the rotating body621is configured to mesh with the gear61aand the gear66a. According to this configuration, when the gravity or centrifugal force works on the weight, the lever671pivots, and the claw671aat the tip end is engaged with the gear66bor66c. For example, when leftward gravity works on the weight, the claw671aof the lever671on the right side is engaged with the gear66b. Therefore, the ball672for pivoting the lever671is unnecessary.

FIG.16Ais a view illustrating further another configuration of the restricting portion. Similarly to the other restricting portions60, a restricting portion70illustrated inFIG.16Ais also disposed to be adjacent to the front end surface of the swing joint50. As illustrated inFIG.16A, the restricting portion70includes a rotating body71, which is coupled with the front end portion of the shaft portion52, and which rotates integrally with the shaft portion52about the axial line La. On an outer circumferential surface of the rotating body71, a plurality of groove portions71aare formed in an uneven shape over the entire circumference. A lock member72(engaging portion) is disposed below the rotating body71so as to be swingable about an axial line L6, which is located on a vertical line L5passing through the axial line La, and which is parallel to the axial line La. The lock member72includes a horizontal portion721extending in the left-right direction, and vertical portions722respectively extending upward from both left and right end portions of the horizontal portion721, and is configured to be left-right symmetric as a whole.

A case73including an upper surface in a substantially concave curved shape is disposed below the lock member72. A ball74is disposed between the lock member72and the case73so as to be movable in the left-right direction. Although not illustrated, the lock member72is swingably supported by, for example, the joint case51, and the case73is fixed to the joint case51.

FIG.16Acorresponds to a state in which the vehicle100travels straight, and in this state, the ball74is located on the vertical line L5. For this reason, the lock member72does not swing, and upper end portions of the left and right vertical portions722are spaced apart from the outer circumferential surface of the rotating body71. Therefore, the rotating body71is rotatable in any of the R1direction and the R2direction, and the rear vehicle body is swingable to the left and right.

From this state, when the vehicle100travels on a lateral-side slope that is inclined upward to the right (FIG.11A) or turns to the right, the ball74moves to the left side as illustrated inFIG.16B. Accordingly, the lock member72swings rightward about the axial line L6as a fulcrum, and the upper end portion of the vertical portion722on the left side of the lock member72is engaged with the groove portion71a of the rotating body71. As a result, the rotation of the rotating body71in the R1direction is inhibited, and a leftward swing of the rear vehicle body is inhibited. In this situation, the rotation of the rotating body71in the R2direction is enabled, and a rightward swing of the rear vehicle body is permitted.

On the other hand, from the state ofFIG.16A, when the vehicle100travels on a lateral-side slope that is inclined upward to the left or turns to the left, the ball74moves to the right side as illustrated inFIG.16C. Accordingly, the lock member72swings leftward about the axial line L6as a fulcrum, and the upper end portion of the vertical portion722on the right side of the lock member72is engaged with the groove portion71a of the rotating body71. As a result, the rotation of the rotating body71in the R2direction is inhibited, and a rightward swing of the rear vehicle body is inhibited. In this situation, the rotation of the rotating body71in the R1direction is enabled, and a leftward swing of the rear vehicle body is permitted.

In the present embodiment, various modifications are available. Hereinafter, some modified examples will be described. In the above embodiments, the rear vehicle body such as the seat frames12and the swing arms13supports the rear wheel2to be rotatable. However, the configuration of the rear vehicle body as a first member is not limited to this. In the above embodiments, the rear vehicle body is provided to be swingable with respect to the front vehicle body such as the side frames11. However, the configuration of the front vehicle body as a second member is not limited to this. The second member may rotatably support the front wheels1. The first member and the second member may have any configuration, as long as they are supported by the coupling member so that the swing amount of the first member is larger than the swing amount of the second member, when swinging in the left-right direction in a state in which the front wheels and the rear wheel are in ground contact with a substantially horizontal ground surface.

In the above embodiments, the rear vehicle body is supported to be swingable with respect to the front vehicle body through the coupling member such as the swing joint50and the coupling plate17. However, the configuration of the coupling member is not limited to the above one, as long as it supports the first member and the second member to be swingable relatively in the left-right direction about an axial line extending in the front-rear direction. Specifically, the coupling member may have any configuration, as long as it is provided so that a first position is closer to the axial line La than a second position, in a case where the first position is set to a position in the left-right direction of an attention point, on the surface of the rear wheel2, that constitutes the center in a contact area between the rear wheel2and the ground surface when the first member swings about the axial line La, and the second position is set to a position in the left-right direction of the attention point before the first member swings about the axial line La.

In the above embodiments, the swing joint50is provided so that the post-swing ground contact point P21(attention point) coincides with the axial line La when the rear vehicle body swings. However, the attention point does not have to coincide with the axial line La, as long as the attention point gets closer to the axial line La after swinging than before swinging. In the above embodiments, the seat3, the guide126, and the like are configured to support the user's buttocks or back. However, an occupant support portion may have any configuration, as long as it is coupled with the first member so as to swing integrally with the first member. In the above embodiments, the steps224on which the user's feet are placed while the user is riding on the vehicle are provided. However, a placement portion may have any configuration, as long as each of them is provided integrally with the second member to enable the occupant's foot to be placed on.

In the above embodiments (FIGS.12to16C), the restricting portions60and70, which restrict swinging of the rear vehicle body are provided. However, a restricting portion may have any configuration, as long as it restricts relative swinging of the first member and the second member. More specifically, the restricting portion is preferably provided to restrict swinging of the first member in a direction that increases an angle formed by a perpendicular plane extending in a direction orthogonal to the axial line in rotation of the rear wheel2and a vertical plane passing through the ground contact point of the rear wheel2, or to permit swinging of the first member in a direction that reduces such an angle. The restricting portion may be provided to restrict swinging of the first member outward in making a turn, or to permit swinging of the first member inward in making a turn, in the turning radius direction of the vehicle100. In particular, the restricting portion is preferably provided so as to inhibit the first member from swinging in at least one of a gravity direction and a centrifugal force direction.

In the above embodiments, the rotating bodies63,66, and71, which operate in conjunction with swinging of the rear vehicle body, are configured to be a movable portion (a first engaging element). However, the first engaging element may have any configuration, as long as it operates in conjunction with swinging of the first member. In other words, the first engaging element may be any element other than the rotating body. In the above embodiments (FIGS.12to15), the engaging portions65and67are respectively configured to include the sprag651and the lever671, which are configured to change the posture between a first posture of engaging with the rotating bodies63and66and a second posture of disengaging from the rotating bodies63and66. In the above-described embodiments (FIGS.16A to16C), the lock member72is configured to be capable of changing the posture between the first posture of engaging with the rotating body71and the second posture of disengaging from the rotating body71. However, the configuration of an engaging portion (a second engaging element) is not limited to the above-described ones. In the above embodiments, the restricting portions60and70respectively include the balls654or672and the ball74movable in the gravity direction and in the centrifugal force direction. However, it is sufficient if a movable body is configured to be capable of rolling, and the shape of the movable body is not limited to a spherical one. For example, the movable body may have a cylindrical shape.

In the above embodiments, the shaft portion52of the swing joint50is fixed to the rear vehicle body, and the joint case51(a case portion) is fixed to the front vehicle body. However, the shaft portion may be fixed to the front vehicle body, and the case portion may be fixed to the rear vehicle body. In the above embodiments (FIGS.12to15), the rotation of the shaft portion52is configured to be transmitted through the circular plate61and the rotating body62, or621and622to the rotating body63or66at an increased speed. However, the configuration of the torque transmitting portion is not limited to this. In the above embodiments, the restricting portions60and70are disposed to be adjacent to the front end surface of the case portion. However, a restricting portion may be disposed to be adjacent to a rear end surface of the case portion, instead of the front end surface. In the above embodiments, the Neidhart damper55including the rubber rollers532each functioning as a repulsive member, is used for the swing joint50. However the configuration of a repulsive member that accumulates the repulsive force when the first member and the second member swing relative to each other and that urges swinging in a direction of returning is not limited to the above-described one.

In the embodiment, the vehicle100is configured as a three-wheeled vehicle with two front wheels and one rear wheel. The vehicle100may have three or more front wheels, or it may have one front wheel and two or more rear wheels. Although in the above embodiment, the vehicle is configured as an electric vehicle with the battery40, the vehicle100may be other than an electric vehicle. In other words, the configuration of a vehicle is not limited to those described above.

The above explanation is an explanation as an example and the present invention is not limited to the aforesaid embodiment or modifications unless sacrificing the characteristics of the invention. The aforesaid embodiment can be combined as desired with one or more of the aforesaid modifications. The modifications can also be combined with one another.

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