JPH02141383A - Rear wheel steering device for motor bicycle - Google Patents

Abstract

PURPOSE:To cause natural steering of a rear wheel through simple structure by utilizing a lateral force exerted on the rear wheel by a method wherein king pins supporting the rear wheel so that they are capable of being deviated in a lateral direction are disposed so that an intersection between the extension lines and a road surface is displaced in a given direction. CONSTITUTION:In a rear arm serving as a rear wheel support member, the rear ends of upper and lower arms 9 and 10 are intercoupled through a rise arm 11 and formed in the shape of a parallelogram link. A fixed cylinder 12 is secured to the central part in a vertical direction of a rise arm 11, and a moving cylinder 13 is pivotally mounted to the front end of a fixed cylinder 12 by means of king pins 21. An axle 15 is inserted in the two cylinders 12 and 13, and a rear wheel 18 is secured to the axle 15. In this case, a pair of the upper and lower king pins 21 are vertically situated to a portion deviated rearwardly by a given distance from the axle 15 located to a coupling part between the two cylinders 12 and 13. An intersection between the axis extension line of the king pin 21 and a road surface G is positioned rearwardly by a given distance from an intersection between the perpendicular of the axle 15 and the road surface ground G.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a motorcycle in which the rear wheels are also steered by steering the front wheels of a motorcycle or by turning the vehicle by shifting the rider's weight. Regarding the rear wheel steering device, the rear wheel I3A steering device is designed so that the rear wheels are also naturally steered by the lateral force acting on the rear wheels by devising the support structure of the rear wheels with respect to the rear wheel support member. Regarding.

[Conventional technology]

In the past, it was common for motorcycles to steer only the front wheels, but recently, by steering the rear wheels as well as the front wheels, it has been possible to improve running stability at medium and high speeds, or to improve driving stability at low speeds. Consideration is being given to reducing the radius of rotation.

An example of such a front and rear wheel steering device for a motorcycle is one in which a front fork to which a steering handle is attached and a rear wheel supported so as to be able to turn left and right are connected via a transmission link with a cam mechanism interposed therebetween. There are (for example, JP-A-61-
(Refer to Publication No. 178275).

[Problem that the invention seeks to solve]

The above-mentioned conventional device has a structure in which the rear wheels are forcibly steered in conjunction with the operation of the steering wheel, so a transmission link, a cam mechanism, etc. are required, and the structure is complicated.

The present invention has been made in view of the above-mentioned conventional situation, and has a simple structure that simply devises the support structure of the rear wheel with respect to the rear wheel support member, and the rear wheel is automatically moved by the lateral force acting on the rear wheel. The purpose of the present invention is to provide a rear wheel steering device for a motorcycle that allows steering.

[Means for solving problems]

The present invention relates to a rear wheel steering device for a motorcycle in which a rear wheel is supported by a kingpin with respect to a rear wheel support member so as to be able to turn left and right.
The kingpin is arranged so that the kingpin intersection point (referred to as the kingpin intersection point) is deviated to the rear or front of the point of application of the lateral force to the rear wheels, so that the rear wheels are steered by the lateral force acting on the rear wheels. It is characterized by what it did.

In the present invention, in order to locate the kingpin intersection point behind or in front of the point of application of lateral force, for example, the kingpin may be arranged vertically behind or in front of the axle, or
Alternatively, it can be realized by arranging it at an angle. Depending on the position, the steering characteristics will be in phase with or out of phase with the front wheels as described later, so choose as appropriate depending on the characteristics you are trying to obtain. becomes.

[Effect]

In the rear wheel steering device according to the present invention, the kingpin intersection point is deviated back and forth from the point of application of lateral force, so that the lateral force (so-called cornering force, canvas thrust) that acts on the rear wheel during a turn causes the kingpin to be applied to the rear wheel. As a result, the rear wheels are naturally steered in response to the lateral force.

If the king pin intersection point is set behind the point of application of the lateral force, the rear wheels are steered in the same direction (in phase) as the front wheels, improving steering stability in medium and high speed ranges.

On the other hand, when the king pin intersection point is set forward of the point of action, the rear wheels are steered in the opposite direction (opposite phase) to the front wheels, the radius of rotation is reduced, and this is advantageous when making small turns at low speeds.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are diagrams for explaining a rear wheel steering device for a motorcycle according to an embodiment of the present invention.

In the figure, ■ is a scooter-type motorcycle in which the device of this embodiment is adopted, and a front fork 4 that pivotally supports a front end 3 at its lower end is rotatably supported on the front part of the body frame 2 of this vehicle so as to be able to turn left and right. A steering shaft 6 having a steering handle 5 fixed to its upper end is pivotally supported by a head pipe 23 formed in a forward extension from the shaft support. The steering shaft 6 is connected to the front fork 4 via a transmission mechanism including a cam, a link, etc., so that the front wheel 3 can be rotated left and right by operating the steering handle 5. .

Further, a four-stroke engine 7 is mounted on the rear portion of the vehicle body frame 2, and a rear arm 8 serving as a rear wheel support member is pivotally supported for vertical movement. This rear arm 8 has the rear ends of the upper and lower arms 9 and 10 connected to each other by the arm 1.
It is a parallelogram link-like structure connected by 1. The upper and lower ends of the vertical arm 11 are swingably connected to the upper and lower arms 9.10 by inserting fastening poles 1-11b into joints 11a containing bearings. Incidentally, reference numeral 1lc (Fig. 4) is an adjustment bolt for moving this vertical arm 11 back and forth to adjust the tension of the tensioner.

Further, a fixed cylinder 12 for holding the rear wheel is fixed to the vertical center of the vertical arm 11, and a movable cylinder 13 is rotatably connected to the front end of this by a king pin 21, which will be described later. There is. An axle 15 consisting of an outer axle and an inner axle 15a15b is inserted into both cylinders 12 and 13, and each is rotatably supported by a bearing 16 and connected by a universal joint 17. A rear wheel 18 is fixed to the inner axle 15b by spline fitting, and a rear wheel sprocket 19 is fixed to the outer axle 15a by spline fitting. A power transmission chino 20 is wound between the two.

Note that 19a is a Cheno case.

Rectangular connecting portions 12a and 13a are formed at opposite ends of the fixed tube 12 and movable tube 13, respectively, and the connecting portion 13a is inserted into the connecting portion 12a. A pair of upper and lower king pins 21 are provided at the portions of the reconnection portions 12a and 13a that are deviated rearward by an amount D from the axle 15.
, 21 are inserted vertically through sliding bearings 22a, 22b, and a washer 22C is inserted between both bearings 22a, 22b. The king pin 21 is fixed to the fixed cylinder 12 side by pressing the head with a cover plate 23 fixed to the fixed cylinder 12 with bolts 24.

As a result, the intersection B of the shaft extension of the king pin 21 with the road surface G is located at the rear of the vehicle by a distance D from the intersection A of the perpendicular line drawn from the axle 15 (see FIG. 5), and the movable cylinder 13 and, by extension, The rear wheel 18 can be turned left and right around this king pin 21 with respect to the fixed cylinder 12.

Further, a pair of upper and lower dampers 26 are arranged in front of the axle 15 of the reconnection parts 12a and 13b, and this damper 26 is for regulating the amount of left and right turning of the movable cylinder 13. be. This damper 2G has inner and outer cylinders 26a
, 26b, and the body 26c is inserted and baked, and is attached to the movable cylinder 13 side. And the inner cylinder 26
A guide portion 27a of the connecting pin 27 is inserted into the inside a, and the head of the connecting pin 27 is inserted! Tentative 23. It is fixed with a bolt 24, so that the amount of rotation of the movable cylinder 13 is regulated by the elasticity of the rubber body 26e.

Next, the effects of this embodiment will be explained.

In the motorcycle 1 of this embodiment, when the front wheel 3 is steered to the left using the steering handle 5, for example, as shown in FIG. As a result, a lateral force F is applied to the rear wheel 18 from the road surface G toward the inside of the turn.
will come into play.

At this time, the point of application of the lateral force can be considered to be approximately at a position A directly below the axle 15. Therefore, a moment corresponding to the product of this lateral force F and the deflection i1D of the king pin 21 acts on the rear wheel 18, and as a result, the rear wheel 18 is steered in the same phase as the front wheel 3, as shown by the broken line in the figure. It will be done.

As described above, in this embodiment, since the king pin 21 is arranged behind the axle 15, the rear wheels 18 can be steered in the same phase as the front wheels 3 by the lateral force during turning, and the steering in the medium speed and high speed ranges is improved. Stability can be improved.

By the way, in the above embodiment, the king pin 21 is connected to the axle 15.
By arranging the rear wheel 18 more rearward and vertically, the rear wheel 18 is aligned with the front wheel 3.
However, in the present invention, it is not necessary to arrange the kingpin vertically. For example, as shown in FIG. 6, by placing the kingpin 21 tilted forward,
The intersection point B of the extension line with the road surface G may be located further back from the point of application.The king pin 21 does not necessarily have to pass through the axle 15.In this case, the rear wheel 18 is connected to the front wheel 3. It can be steered in the same phase as the

Further, in the above embodiment, a case has been described in which the rear wheels are steered in the same phase as the front wheels, but according to the present invention, the rear wheels can also be steered in the opposite phase to the front wheels.

In this case, as shown in FIG. 7(a), the kingpin 21
The king pin 21 may be tilted rearward, or the king pin 21 may be placed vertically in front of the axle 15 as shown in FIG.

〔Effect of the invention〕

As described above, according to the rear wheel steering device for a motorcycle according to the present invention, the kingpin is arranged such that the intersection of the kingpin extension line with the road surface is located behind or in front of the point of application of lateral force to the rear wheel. Therefore, the rear wheels can be steered by the lateral force generated during turning, and there is an effect that rear wheel steering can be realized without providing a complicated mechanism.

[Brief explanation of the drawing]

1 to 5 are diagrams for explaining a rear wheel steering device for a motorcycle according to an embodiment of the present invention, in which FIG. 1 is a cross-sectional side view of the kingpin portion, and FIG. 2 is a cross-sectional side view of the rear wheel portion. 3 is a cross-sectional plan view thereof, FIG. 4 is a side view of a motorcycle to which the embodiment device is applied, and FIG.
(bl is a schematic plan view for explaining the operation,
6 is a side view schematically showing a modification of the kingpin arrangement structure, and FIGS. 7A and 7B are side views schematically showing another modification of the kingpin arrangement structure. , l is the motorcycle, 8 is the rear arm (rear wheel support member), 1st is the rear wheel, 21 is the kingpin, A is the point of action, B is the intersection, D is the amount of deviation, and F is the lateral force.Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Disembarking Group 2nd Ward 3rd Figure Figure 6A/, Color

Claims (1)

[Claims] (1) In a rear wheel steering device for a motorcycle in which the rear wheel is supported by a kingpin with respect to a rear wheel support member so as to be able to turn left and right, the intersection of the extension line of the kingpin and the road surface is the rear wheel of the rear wheel due to lateral force. 1. A front and rear wheel steering device for a motorcycle, characterized in that the front and rear wheel steering device for a motorcycle is arranged so as to be deviated rearward or forward from a point of application to the rear wheel, so that the rear wheel is steered by the lateral force acting on the rear wheel.