JP2024060254A - Rear two-wheel vehicle - Google Patents

Abstract

[Problem] To prevent a two-wheeled vehicle from tipping over when stopped and ensure stable running. [Solution] In a two-wheeled vehicle in which a front wheel F is steered left and right by rotating a handle post 3 rotatably supported on a frame 1, and a rear wheel R has two wheels W, W arranged in parallel in the vehicle width direction, the vehicle is equipped with rear wheel support parts 7, 9 provided at the rear of the frame 1, a link mechanism 10 connected to the rear wheel support parts 7, 9, a pair of axles B, B supported by the link mechanism 10 or the rear wheel support parts 7, 9 and separately supporting the two wheels W, W, an auxiliary axle B' that rotates about its axis due to driving force, and a driving force transmission mechanism 40 that transmits the rotation of the auxiliary axle B' about its axis to the pair of axles B, B. [Selected Figure] Figure 1

Description

This invention relates to a two-wheeled vehicle with two rear wheels arranged side by side in the vehicle width direction.

There are two-wheeled vehicles with two wheels arranged side by side in the width direction of the vehicle body. For example, the two-wheeled vehicles in Patent Documents 1 and 2 have a frame extending in the front-rear direction of the vehicle body, a cylindrical center post provided at the front end of the frame, and a steering mechanism for the front wheels attached to the center post. The steering mechanism is composed of a front fork member that rotatably supports the front wheel, a handle post inserted into the center post, a steering handle, etc. In addition, a rear wheel holder that supports the axle between the left and right rear wheels is connected to the rear end of the frame. When the driver rotates the crank pedal with his/her foot pressure, the rear wheel is driven via a chain.

Furthermore, electric-assisted bicycles with two rear wheels are provided with a pedaling force assist device near the center of the frame that assists the pedaling force of the rider. The crank pedal to which the rider's pedaling force is input is connected to the pedaling force assist device, and the driving force is transmitted to the axle connecting the left and right tire wheels of the rear wheel via a shaft and chain. In recent years, two rear wheels have also been put to practical use in motorcycles equipped with a prime mover such as an engine.

Japanese Patent Application Laid-Open No. 10-264875 Japanese Patent Application Laid-Open No. 10-264872

In conventional two-wheeled vehicles, a swing mechanism is provided between the rear wheel holder, which supports the axle between the left and right rear wheels, and the frame of the vehicle body. In a two-wheeled vehicle equipped with a swing mechanism, the left and right rear wheels can be kept on the ground and smooth driving can be achieved by tilting the vehicle body when passing through intersections or curves. However, in a two-wheeled vehicle, the two rear wheels do not swing, only the frame swings. This results in insufficient load transfer when turning, and stable driving may not be ensured depending on the driving conditions.

The objective of this invention is to ensure stable driving in a two-wheeled vehicle with two rear wheels arranged side by side in the vehicle width direction.

In order to solve the above problems, the present invention provides a two-wheeled vehicle in which the front wheels are steered left and right by rotating a handle post rotatably supported on a frame, and the rear wheels are arranged in parallel in the vehicle width direction, the vehicle being provided with a rear wheel support section provided on the rear of the frame, a link mechanism connected to the rear wheel support section, a pair of axles supported by the link mechanism and separately supporting the two wheels, an auxiliary axle supported by the link mechanism or the rear wheel support section and rotating around its axis due to driving force, and a driving force transmission mechanism that transmits the rotation of the auxiliary axle around its axis to the pair of axles.

Here, the link mechanism can be configured to include an upper link bar and a lower link bar arranged in the vehicle body width direction, and a pair of vertical link bars connecting both ends of the upper link bar and the lower link bar, and the pair of axles can be supported on the lower link bar via a bearing unit so as to be freely rotatable about their axes.

In each of these aspects, the drive force transmission mechanism can be configured to include a pair of first rotating members attached to the auxiliary axle so as to rotate integrally therewith, a pair of second rotating members attached to each of the pair of axles so as to rotate integrally therewith, and a pair of endless members wound around the pair of first rotating members and the pair of second rotating members, respectively.

This invention ensures stable driving in a two-wheeled vehicle with two rear wheels arranged side by side in the vehicle width direction.

FIG. 1 is an overall view showing a first embodiment of the present invention; FIG. 1 is a side view of a rear wheel in a straight traveling state, as viewed from the front side of a vehicle body, showing the first embodiment of the present invention. FIG. 1 is a side view of the rear wheel in a left steering state as viewed from the front side of the vehicle body according to the first embodiment. FIG. 1 is a side view of a rear wheel in a straight traveling state as viewed from the rear side of the vehicle body according to the first embodiment. FIG. 1 is a side view of the rear wheel in a left steering state as viewed from the rear side of the vehicle body according to the first embodiment. FIG. 1 is an enlarged bottom view of a main part of a rear wheel according to a first embodiment; FIG. 1 is an enlarged side view of a main part of a rear wheel according to a first embodiment; FIG. 11 is a side view of the rear wheel in a straight traveling state, as viewed from the front side of the vehicle body, showing the second embodiment of the present invention. FIG. 11 is a side view of the rear wheel in the left steering state as viewed from the front side of the vehicle body, showing the second embodiment. FIG. 13 is an enlarged bottom view of a main part showing a rear wheel according to a second embodiment; FIG. 11 is an enlarged side view of a main part of a rear wheel according to a second embodiment of the present invention; FIG. 11 is a side view of the rear wheel in a straight running state, as viewed from the front side of the vehicle body, showing the third embodiment of the present invention. FIG. 13 is a side view of the rear wheel in the left steering state as viewed from the front side of the vehicle body, showing the third embodiment. FIG. 13 is an enlarged bottom view of a main part showing a rear wheel according to a third embodiment; FIG. 13 is an enlarged side view of a main part of the rear wheel according to the third embodiment;

A two-wheeled vehicle C according to an embodiment of the present invention will be described with reference to the drawings. Figures 1 to 5 show a first embodiment, Figures 6A to 8 show a second embodiment, and Figures 9A to 11 show a third embodiment. In each embodiment, the present invention is described using a two-wheeled bicycle with one wheel W on the front wheel F and two wheels W, W arranged in parallel in the width direction of the body as rear wheels RL/RR. The two-wheeled bicycle is assumed to be a two-wheeled bicycle that runs only with the driving force associated with pedaling by human power, or an electrically assisted two-wheeled bicycle that uses the driving force of a motor as a driving force to assist human power, but the present invention can also be applied to motorized bicycles that do not use human power as a driving force (two-wheeled motorized bicycles) and other bikes (two-wheeled trikes (special two-wheeled vehicles)).

(First embodiment)
1, the basic configuration of the two-wheeled rear vehicle C of the first embodiment includes a frame 1 extending in the front-rear direction of the vehicle body, a cylindrical center post (head tube) 4 provided at the front end of the frame (down tube) 1, and a front wheel steering mechanism attached to the center post 4. The steering mechanism includes a front fork member 5 that supports one wheel (tire wheel) W constituting a front wheel F so as to be rotatable about an axle A, and a handle post 3 that is inserted into the center post 4 to support the front fork member 5, and a steering handle 2 is connected to the upper end of the handle post 3 by a clamp member.

A saddle 8a is attached to the top of a seat tube 8 that rises from the frame 1 and can be raised and lowered. The rider sitting on the saddle 8a can grip and operate the steering handle 2 by gripping the grip parts 2a at both ends. Brake levers are provided at both ends of the steering handle 2 to adjust the braking force applied to the front wheel F and the rear wheels RR/RL. When the rider turns the steering handle 2 left and right, the handle post 3 rotates about its axis and the front wheel F is steered left and right. The front fork member 5 is composed of a single axle on the upper side, like a typical front and rear two-wheel bicycle, and is bifurcated on the wheel W side, with the tips supporting both ends of the axle A of the wheel W.

The frame 1 also has a seat stay 7 and a chain stay 9 integrated at its rear. The seat stay 7 has a first member 7a that rises upward from the rear end of the chain stay 9, a second member 7b that protrudes rearward from the middle of the first member 7a that faces up and down, and a third member 7c that connects the upper end of the seat tube 8 and the upper end of the first member 7a. The seat stay 7 also has a fourth member 7d that protrudes rearward from the lower end of the first member 7a (the rear end of the chain stay 9). Hereinafter, the seat stays 7 and the chain stays 9 are collectively referred to as the rear wheel support parts 7, 9.

A link mechanism (swing mechanism) 10 is connected to the rear wheel support parts 7, 9. A pair of axles B, B that separately support the two wheels (tire wheels) W, W that make up the rear wheels RR/RL are also connected to the link mechanism 10. The pair of axles B, B are composed of separate, discontinuous axles. Furthermore, the link mechanism 10 or the rear wheel support parts 7, 9 supports an auxiliary axle B' that rotates around its axis by driving force so that it can rotate around its axis, and a driving force transmission mechanism 40 is provided between the auxiliary axle B' and the pair of axles B, B to transmit the rotation of the auxiliary axle B' around its axis to the pair of axles B, B. The rear wheel unit U is composed of these devices attached to the rear wheel support parts 7, 9, i.e., the link mechanism 10, axles B, B, the auxiliary axle B', the two wheels W, W of the rear wheels RR/RL, the driving force transmission mechanism 40, etc.

The link mechanism 10 includes an upper link bar 11 and a lower link bar 12 arranged in the vehicle body width direction, and a pair of vertical link bars 13, 13 that connect both ends of the upper link bar 11 and the lower link bar 12, respectively. The lower link bar 12 is arranged below the upper link bar 11.

The upper link bar 11 is a longitudinal member arranged in the vehicle width direction. The upper link bar 11 can swing freely around the axis of the swing shaft 15 relative to the rear wheel support parts 7, 9. In this embodiment, the swing shaft 15 is fixed to the second member 7b of the rear wheel support part 7 and penetrates the longitudinal center of the upper link bar 11. The upper link bar 11 can swing freely around the axis of the swing shaft 15. Here, a bearing may be arranged between the swing shaft 15, which is fixed to the frame (second member 7b), and the upper link bar 11, or the swing shaft 15 and the upper link bar 11 may be integrated and a bearing may be arranged between the frame (second member 7b) and the swing shaft 15.

The lower link bar 12 is a longitudinal member arranged in the vehicle body width direction. The lower link bar 12 can freely swing around the axis of a swing shaft 18 relative to the rear wheel support parts 7, 9. In this embodiment, the swing shaft 18 is fixed to the lower end of the second member 7b of the rear wheel support part 7 and penetrates the center of the lower link bar 12 in the longitudinal direction. The support structure of the swing shaft 18 to the frame (second member 7b) can be the same as that of the swing shaft 15.

The pair of vertical link bars 13, 13 have their upper and lower ends pin-connected to both ends of the upper link bar 11 and the lower link bar 12, respectively, and the upper link bar 11, the lower link bar 12, and the pair of vertical link bars 13, 13 form a four-joint crank mechanism. For example, if the second member 7b is oriented vertically, the four-joint crank mechanism deforms so that when the right end of the upper link bar 11 in the vehicle width direction rises, the left end in the vehicle width direction lowers, and when the right end of the upper link bar 11 in the vehicle width direction lowers, the left end in the vehicle width direction rises. At this time, the lower link bar 12 moves while maintaining a parallel state with the upper link bar 11.

The pair of axles B, B are supported by the link mechanism 10 via bearing units 46 so as to be rotatable about their axes. As shown in FIG. 4, the bearing unit 46 has two rolling bearings 46a arranged in parallel inside the housing, and is configured to support a rotating shaft 47 that rotates integrally with the two axles B, B so as to be rotatable about its axis. In this embodiment, the housing of the bearing unit 46 is supported by both ends of the lower link bar 12 of the link mechanism 10, but it may also be supported by the lower end of the vertical link bar 13.

The auxiliary axle B' is supported so as to be rotatable about its axis by an auxiliary axle support 44 fixed to the link mechanism 10 or the rear wheel support parts 7 and 9. In this embodiment, the auxiliary axle support 44 is fixed to the lower link bar 12 (see the bottom view of FIG. 4 and the side view of FIG. 5), but it may also be fixed to the lower end of the vertical link bar 13 or to the rear wheel support parts 7 and 9.

As shown in FIG. 5, the auxiliary axle support 44 in this embodiment is composed of a first support member 44e made of a plate-like member protruding forward from the lower link bar 12, and a second support member 44f with an L-shaped cross section that is fixed to the first support member 44e by fixing means 44a made of bolts, nuts, etc. The rotating shaft 45 that rotates integrally with the auxiliary axle B' is supported rotatably about its axis via a bearing 48 on a third support member 44c that is fixed to the second support member 44f by fixing means 44b made of bolts, nuts, etc.

The link mechanism 10 may also include a spring mechanism as a suspension to absorb shock from the wheels W, W to the frame 1. For example, a pair of left and right coil springs connecting both ends of the upper link bar 11 and the lower link bar 12 can be used as the spring mechanism. Both ends of each coil spring can be pin-joined to both ends of the upper link bar 11 and the lower link bar 12, respectively, to form a four-section crank mechanism with the left and right spring mechanisms, the upper link bar 11, and the lower link bar 12.

The driving force transmission mechanism 40 also includes a pair of first rotating members 41, 41 attached to the auxiliary axle B' so as to rotate together, a pair of second rotating members 43, 43 attached to the pair of axles B, B so as to rotate together, and a pair of endless members 42, 42 wound around one of the pair of first rotating members 41 and one of the pair of second rotating members 43, and the other of the pair of first rotating members 41 and the other of the pair of second rotating members 43. In this embodiment, a belt is used as the endless member 42, and pulleys are used as the first rotating member 41 and the second rotating member 43, but the endless member 42 is not limited to a belt as in the embodiment, and other members such as a chain may be used. When a chain is used as the endless member 42, sprockets can be used for the first rotating member 41 and the second rotating member 43.

In the embodiment, an endless chain 53 is wound between the front sprocket 51 to which the crank pedal 55 is connected and the rear sprocket 52 attached to the auxiliary axle B' so as to rotate together with it, but this chain 53 may be an endless belt and the front sprocket 51 and the rear sprocket 52 may be pulleys.

When the driver rotates the crank pedal 55 with his/her pedaling force, the auxiliary axle B' rotates via the front sprocket 51, rear sprocket 52, and chain 53 due to the driving force. The front sprocket 51 rotates integrally with the rotating shaft 54 of the crank pedal 55, and the rear sprocket 52 rotates integrally with the auxiliary axle B'. When the auxiliary axle B' rotates, the pair of axles B, B rotate via the first rotating members 41, 41, the endless members 42, 42, and the second rotating members 43, 43, and the two wheels W, W of the rear wheels RL/RR rotate. This causes the rear two-wheel vehicle C to move. The reference numeral 62 in each of the figures from FIG. 2A onwards is a brake disc (brake pads and brake calipers are not shown). The brake disc 62 is provided on each of the wheels W, W.

When the driver operates the steering handle 2 to rotate the handle post 3 about its axis, the wheels W of the front wheels F change direction and steering is performed. At this time, the load shifts in the steering direction of the driver (shifting the center of gravity to the right when steering to the right, and to the left when steering to the left) and this causes the frame 1 and the rear wheel support parts 7, 9 to swing left and right relative to the wheels W, W of the rear wheels RL/RR.

Figure 2A (view of the rear wheels from the front of the vehicle body) and Figure 3A (view of the rear wheels from the rear of the vehicle body) show the two-wheeled vehicle C in a neutral state moving straight ahead, while Figure 2B (view of the rear wheels from the front of the vehicle body) and Figure 3B (view of the rear wheels from the front of the vehicle body) show the left turning state.

For example, when the driver turns the steering wheel 2 to the right (when attempting to turn right), the frame 1 and rear wheel supports 7, 9 tilt to the right, pushing the lower link bar 12 to the left and, conversely, the link mechanism 10 deforms in such a direction that the upper link bar 11 is pushed to the right. This causes the frame 1 and rear wheel supports 7, 9 to tilt quickly to the right, facilitating the shifting of the driver's center of gravity and making the vehicle turn to the right smoother. At this time, the wheels W, W of the rear wheels RL/RR also tilt so that their upper ends are more to the right than their lower ends, making the shifting of the driver's center of gravity even smoother.

For example, when the driver turns the steering wheel 2 to the left (when attempting to turn left), as shown in Figures 2B and 3B, the frame 1 and rear wheel supports 7, 9 tilt to the left, pushing the lower link bar 12 to the right and, conversely, the link mechanism 10 deforms in a direction that pushes the upper link bar 11 to the left. This causes the frame 1 and rear wheel supports 7, 9 to tilt quickly to the left, facilitating the shifting of the driver's center of gravity and making the vehicle turn left smoother. At this time, the wheels W, W of the rear wheels RL/RR also tilt so that their upper ends are more leftward than their lower ends, making the shifting of the driver's center of gravity even smoother. This makes it possible to ensure stable driving by appropriately tilting the vehicle body.

Here, in the neutral state, the axial direction of the auxiliary axle B' is parallel to the axial direction of the paired axles B, B (see Figs. 2A and 3A), whereas during turning, the axial direction of the auxiliary axle B' cannot be kept parallel to the axial direction of the paired axles B, B (see Figs. 2B and 3B). In other words, the first rotating members 41, 41 and the second rotating members 43, 43 are in a twisted state. However, the endless members 42, 42 each deform appropriately in response to the twist, and the state of transmission of the driving force from the first rotating members 41, 41 to the second rotating members 43, 43 can be maintained, so that the rear two-wheeled vehicle C can continue to run.

In this embodiment, the upper link bar 11 is made of a single continuous member over its entire length, but it may be divided into a first upper link bar located on one side of the vehicle width (the right side as seen by the driver) and a second upper link bar located on the other side of the vehicle width (the left side as seen by the driver). In addition, the lower link bar 12 is also made of a single continuous member over its entire length, but it may be divided into a first lower link bar located on one side of the vehicle width (the right side as seen by the driver) and a second lower link bar located on the other side of the vehicle width (the left side as seen by the driver). This is the same for each embodiment described below.

Second Embodiment
The second embodiment of the present invention will be described with reference to Figures 6A, 6B, 7 and 8. The basic configuration of the two-wheeled rear vehicle C is similar to that of the first embodiment, so the following description will focus on the support structure of the auxiliary axle B', which is the difference from the first embodiment.

In this embodiment, the auxiliary axle B' is supported so as to be rotatable about its axis by an auxiliary axle support part 44 fixed to the rear wheel support parts 7 and 9 (see Figures 7 and 8). In this embodiment, the auxiliary axle support part 44 is supported so as to be swingable on the rear ends of the rear wheel support parts 7 and 9.

The pair of axles B, B are supported by the link mechanism 10 via bearing units 46 so as to be rotatable about their axes. As shown in FIG. 7, the bearing unit 46 has two rolling bearings 46a arranged in parallel inside the housing, and is configured to support a rotating shaft 47 that rotates integrally with the two axles B, B so as to be rotatable about its axis. In this embodiment, the housing of the bearing unit 46 is supported by both ends of the lower link bar 12 of the link mechanism 10, but it may also be supported by the lower end of the vertical link bar 13.

7 and 8, the auxiliary axle support 44 of this embodiment is composed of a first support member 44e made of a plate-like member and a shaft-like second support member 44f provided to protrude forward from the first support member 44e. The first support member 44e is provided along the width direction of the vehicle body and is supported by a pair of connecting members 44j arranged in the vertical direction with respect to the lower link bar 12 (see Figs. 6A and 6B). The lower link bar 12 and the connecting member 44j, and the first support member 44e and the connecting member 44j are connected rotatably via pins 44h and 44i, respectively. The first support member 44e is supported rotatably via a bearing 7g on a fifth member 7f that protrudes downward from the connection portion between the seat stay 7 and the chain stay 9 that constitute the rear wheel support portion 7, 9. The fifth member 7f has a support portion 7e that protrudes toward the rear, and the first support member 44e fits into the support portion 7e via a bearing 7g and is held in place by a nut 7h that is screwed in from the rear side of the vehicle body. The rotating shaft 45 that rotates integrally with the auxiliary axle B' is supported by the second support member 44f via a bearing 48 so that it can rotate freely around its axis.

In this embodiment, a belt is used as the endless member 42, and pulleys are used as the first rotating member 41 and the second rotating member 43, but like the other embodiments, other members such as a chain can be used as the endless member 42, and sprockets can be used as the first rotating member 41 and the second rotating member 43.

Third Embodiment
A third embodiment of the present invention will be described with reference to Figures 9A, 9B, 10 and 11. In this embodiment, the auxiliary axle B' is also supported rotatably about its axis by an auxiliary axle support part 44 fixed to the rear wheel support parts 7, 9 (see Figures 10 and 11). The configuration of the bearing unit 46 is the same as in the above-mentioned embodiments.

In this embodiment, the auxiliary axle support 44 is composed of a fourth support member 44k that protrudes on both sides in the vehicle width direction from the rear ends of the rear wheel support parts 7, 9 (chain stays 9), and a fifth support member 44m made of a plate-shaped member fixed to the fourth support member 44k so as to protrude downward. The rotating shaft 45 that rotates integrally with the auxiliary axle B' is supported on the fifth support member 44m via a bearing 48 (not shown) so as to be rotatable about its axis.

In addition, in this embodiment, a chain is used as the endless member 42, and sprockets are used for the first rotating member 41 and the second rotating member 43, so a chain tensioner 49 is provided to adjust the slack in the chain.

As shown in FIG. 11, the chain tensioner 49 is configured to include an arm 49b supported so as to be able to swing up and down relative to the fifth support member 44m, a small sprocket 49a rotatably provided at the swing end of the arm 49b, and an elastic member 49c that biases the swing end of the arm 49b toward the endless member 42. Installation of such a chain tensioner 49 can also be omitted.

In each of the above embodiments, the rear wheel support parts 7, 9 are formed by the seat stays 7 and the chain stays 9, but the configuration of the rear wheel support parts 7, 9 can be variously adopted depending on the specifications of the vehicle.

In addition, in each of the above embodiments, the contents of this invention have been explained using a two-wheeled bicycle as an example, but the invention can also be applied to various types of two-wheeled vehicles C in which the frame 1 can swing left and right, such as an electrically assisted bicycle (an electrically assisted bicycle with two rear wheels) equipped with a pedaling force assist device that uses the driving force of a motor to assist the rider's pedaling force, a moped (a moped with two rear wheels), and other bikes (two-wheeled trikes (special two-wheeled vehicles)).

1 Frame 2 Steering handle 3 Handle post 4 Center post 7, 9 Rear wheel support portion 10 Link mechanism (swing mechanism)
11 Upper link bar 12 Lower link bar 13 Vertical link bar 40 Driving force transmission mechanism 41 First rotating member 42 Endless member 43 Second rotating member B Axle B' Auxiliary axle C Rear two-wheel vehicle

Claims (3)

A two-wheel vehicle in which a front wheel (F) is steered left and right by rotating a handle post (3) rotatably supported on a frame (1), and a rear wheel (R) is provided with two wheels (W, W) arranged in parallel in the vehicle width direction,
A two-wheeled rear vehicle comprising: a rear wheel support section (7, 9) provided at the rear of the frame (1); a link mechanism (10) connected to the rear wheel support section (7, 9); a pair of axles (B, B) supported by the link mechanism (10) and separately supporting the two wheels (W, W); an auxiliary axle (B') supported by the link mechanism (10) or the rear wheel support section (7, 9) and rotated about its axis by driving force; and a driving force transmission mechanism (40) that transmits the rotation of the auxiliary axle (B') about its axis to the pair of axles (B, B). The link mechanism (10) includes an upper link bar (11) and a lower link bar (12) provided in the vehicle body width direction, and a pair of vertical link bars (13, 13) connecting both ends of the upper link bar (11) and the lower link bar (12), respectively;
2. The two-wheel rear vehicle according to claim 1, wherein the pair of axles (B, B) are supported on the lower link bar (12) via a bearing unit (46) so as to be rotatable about their axes. The two-wheeled rear vehicle according to claim 1 or 2, wherein the driving force transmission mechanism (40) comprises a pair of first rotating members (41, 41) attached to the auxiliary axle (B') so as to rotate integrally therewith, a pair of second rotating members (43, 43) attached to the pair of axles (B, B) so as to rotate integrally therewith, and a pair of endless members (42, 42) wound around the pair of first rotating members (41) and the pair of second rotating members (43, 43), respectively.