WO2010038225A2

WO2010038225A2 - Suspension system for the front wheel of a two-wheeled vehicle, namely bicycles and motorcycles

Info

Publication number: WO2010038225A2
Application number: PCT/IE2009/000069
Authority: WO
Inventors: Robert Rae
Original assignee: Robert Rae
Priority date: 2008-10-03
Filing date: 2009-09-30
Publication date: 2010-04-08
Also published as: IE20080796A1

Abstract

A suspension system for the front wheel of a two-wheeled vehicle, namely bicycle or motorcycle. A pivoted control arm extends forward from the main body of the two-wheeled vehicle, on which is a ball joint with attachment to a kingpin. The kingpin receives the front wheel axle and also pivots with a vertical steering member. This steering member is attached via a second ball joint to the body. Handlebars, or methods of steering, are attached to, or connected to by mechanical means, steering member/s and are positioned close to the upper ball joint. The positioning of ball joints determines the steering axis. Suspension motion is determined by the control arm, kingpin, and steering member, where means of suspension dampening is/are attached to at least one suspension member. The system minimises the tendency to dive under front wheel braking, and provides superior feeling from the front wheel through the method/s of steering.

Description

TITLE.

SUSPENSION SYSTEM FOR THE FRONT WHEEL OF A TWO-WHEELED VEHICLE, NAMELY BICYCLES AND MOTORCYCLES

DESCRIPTION OF THE INVENTION.

Background of the invention.

The invention disclosed herein is generally related to two-wheeled vehicles. More particular, the present invention is related to suspension and steering systems for the front wheel of two-wheeled vehicles.

Modern two-wheeled vehicles, namely bicycles and motorcycles, with front suspension systems are equipped universally with a fork type system. Such a system includes a pair of telescopic tubes. These telescopic tubes are inverted one inside the other and contain internal springs and dampeners. The fork tubes are connected through a head assembly to a freely rotating steering column which is attached to the main frame of the two- wheeled vehicle. The axle for the front wheel is fixed perpendicular to the lower ends of the said fork tubes. This simple structure has been a basic element of two-wheeled vehicle design for many years. Nevertheless, the conventional fork design suffers from certain disadvantages which have long been recognised but never been completely overcome. For example, there is a well known tendency for the two-wheeled vehicle to 'dive', or pitch forward and downward, during hard braking of the front wheel. This tendency has been partially but not adequately mitigated by the advent in recent years of complex anti-dive mechanisms, some of which operate essentially by increasing the compression pressure in the fork tube shock absorbers during braking of the front wheel. Other designs of anti-dive mechanisms include mechanically levered systems which have brake calliper attachment plus further connection to a position relative to the body whereby utilising torque on the calliper/s, generated from the slowing process of the front wheel, to resist compression of the front suspension. Further, there is a fundamental design problem which arises from the fact that the tubes must bear sizable lateral loads and yet also slide smoothly in a telescoping manner during suspension travel. Lateral stresses exist because the fork is necessarily oriented with a 'rake angle' i.e. the fork extends at an angle upwardly and rearward from the front wheel axle to the steering column. A substantial rake angle is necessary because it renders the fork action most efficient in absorbing road shocks, which are directed both upward and rearward from the front wheel. However, the weight load of the two-wheeled vehicle is purely vertical. If the fork is raked, this results in a lateral stress and consequent frictional resistance to suspension travel. This problem is normally resolved by using large diameter sliding bushings in the telescoping fork tubes to bear such lateral stresses with a minimum of frictional resistance. As a result, however, the shock absorption performance of the fork tube suspension system varies with the weight and shock loads on the two-wheeled vehicle.

Designs of mechanical linkage front suspension have been devised to mitigate performance deficiencies associated with how shock loads are received by the telescopic forks and their resulting operation, but when complex mechanical designs are utilised there is a loss of feeling experienced at the handlebars due to a remoteness of connection from the front wheel axle to the steering control methods, which, in general, are the handlebars. This loss of feeling can result in a handling disadvantage, thereby making operation of such mechanical linkage front suspension equipped two- wheeled vehicles less safe than would be the case with conventional telescopic fork equipped two-wheeled vehicles.

As a general design principle, it is desirable that weight and road loads be transmitted in the simplest and shortest possible manner in order to minimise the weight of the structures which must transmit and bear these loads. It is further desirable from the standpoint of stability to have the centre of gravity of the two-wheeled vehicle as low as possible centred between the two wheels. It is also desirable to have the most direct connection between the front wheel axle and the mechanisms used for steering the front wheel. Further, it is also desirable to have as few moving components in a suspension system as possible, so to reduce complication, manufacturing costs, and also to reduce the inertia associated with both steering motion and suspension action. In view of these objectives, it will be recognised that one disadvantage of the fork- type suspension system is that the load path from the front wheel to the body of the two-wheeled vehicle must pass through the steering shaft and the associated steering head in which the steering shaft is contained. This results in a load path which is angular and lengthy. It also requires the steering shaft, the steering head and their supporting structures to be considerably stronger and heavier than would otherwise be necessary to simply accommodate the torque necessary to effect steering, i.e. if a major weight and shock load-bearing function were not also required. The angular load path also results in shock loads being transmitted to a high point on the frame, in the vicinity of the steering shaft, which is sufficiently far removed from the centre of gravity on the two-wheeled vehicle to result in an undesirable pitching motion in response to road shocks. This response is in effect due to the large polar moment of inertia that results from absorbing road shocks at a point far from the centre of gravity.

There is yet another disadvantage of the conventional telescopic fork suspension. This disadvantage arises from the fact that, because of the rake angle discussed above, the front wheel has a component of motion during suspension travel that is forward and rearward relative to the body of the two-wheeled vehicle. Consequently, it is necessary to provide a considerable clearance between the front wheel and the body in order to allow rearward motion of the front wheel in response to road shocks. In some cases this increases the wheelbase of the two-wheeled vehicle beyond that which would otherwise be desirable solely from the standpoint of performance considerations. In other cases it results in components being positioned close to the rear wheel in order to minimise wheelbase, thereby resulting in the seat of the two- wheeled vehicle being higher than may be desired.

Accordingly, it is the object and purpose of the present invention to provide an improved suspension and steering system for the front wheel of the two-wheeled vehicle.

In this regard, it is a more specific objective of this invention to provide in a two- wheeled vehicle a front suspension system that transfers weight and shock loads in a direct path from the front wheel in the direction of the body that is low and close to the centre of gravity of the two-wheeled vehicle.

It is another objective of the present invention to provide a suspension system in which there is maintained a substantially constant geometry throughout the entire range of ordinary suspension travel.

It is another objective of this invention to provide in a two-wheeled vehicle a front suspension and steering system that minimises bump-steer and diving.

It is another objective of this invention to provide in a two-wheeled vehicle a front suspension and steering system that will transfer ample feeling from the front wheel through to the means used for steering control.

It is another objective of this invention to provide in a two-wheeled vehicle a front suspension and steering system with as few moving components as possible so to reduce manufacturing costs thereof and enhance performance thereof.

It is yet another objective of the invention to provide in a two-wheeled vehicle a front suspension and steering system in which the travel of the front wheel in response to road shock is in a substantially vertical direction, thereby permitting other favourable design changes to be incorporated into the body of the two-wheeled vehicle which have heretofore been prohibited in conventional designs by the requirements to provide for travel of the front wheel in a fore-and-aft direction.

Additional objects of the present invention include the provision of brake and spring/dampener assemblies for the suspension system described below.

Detailed description of the invention.

The foregoing and other objects are attained in the present invention, which provides a one-sided suspension system incorporating a quadrilateral construction. The suspension system includes a lower control arm hinged with the body of the two- wheeled vehicle, extending outward from a pivot point on the said body along the longitudinal axis of which, for substantially vertical swinging motion, where at the outward end of the said arm is a ball joint, or similar, permitting universal movement, where said ball joint, or similar, further attaches to a kingpin. The said control arm is accurately shaped, extending outwardly from the body to one side so to provide sufficient clearance for the front wheel to turn through a full range of steering motion.

The said lower ball joint, or similar, lies in the central longitudinal plane of the two- wheeled vehicle, which also corresponds with the centre plane of the wheel when in its unturned position. The front wheel is either offset to accommodate this, or the hub of the front wheel is offset for such accommodation.

The kingpin is connected to the control arm by means of this ball joint, or similar, where in a position relatively close to, and either above, below, in either side of, or centred with the said ball joint, or similar, is held the axle to receive the front wheel. This kingpin may be single or double-sided relating to its function on either side of the front wheel, it may also be constructed of separate parts, essentially so when it is positioned to hold both sides of the front wheel axle and/or when it is hinged with the steering strut but with the pivot point separated and/or obstructed by the sides of the front wheel. It is positioned, extending in an outward direction from the wheel axle and lower ball joint, or similar, which corresponds with travelling along the longitudinal axis of the two-wheeled vehicle when travelling away from the body. This kingpin is hinged at its outward end with the steering strut, having an axis of rotation extending transversely in respect to the longitudinal plane of the kingpin, where this pivot point is positioned somewhere between an outer periphery of the front wheel and within an inner periphery of the front wheel but at a substantial distance from the front wheel axle. This hinge axis of the kingpin plus the front wheel axle always remain in parallel throughout ordinary steering and suspension motion, whereas neither remain in parallel with the hinge axis for the said control arm once the wheel is turned from its straight ahead position.

The steering strut extends upward and rearwards from its attachment at the pivot point with the kingpin to where there is second attachment, by means of a second ball joint, or similar, which permits universal movement, and is further attached onto the body of the two-wheeled vehicle by means of this ball joint, or similar, where this area can be considered the steering-head. Handlebars, or other methods used for steering control of the front wheel, are an integrated part of, attached to, or connected to by mechanical means, the said steering strut. Handlebars or methods used for steering control can, when there is mechanical connection, have connection to both steering strut and body. In a preferred embodiment of this invention, the handlebars or methods used for steering control are attached rigidly to the steering strut with their position for the function of manual control being close to the said upper ball j oint/steering-head.

Alternatively, the handlebars or other methods used for steering control can connect with the kingpin, or with the kingpin and body, or with the kingpin and steering strut, or with the kingpin steering strut and body. As a further alternative, the handlebars or other methods used for steering control can connect with the front wheel axle, or with the front wheel axle and kingpin, or with the front wheel axle and steering strut, or with the front wheel axle and body, or with the front wheel axle kingpin and steering strut, or with the front wheel axle kingpin and body, or with the front-wheel axle steering strut and body, or with the front wheel axle kingpin steering strut and body.

The said upper ball joint, or similar, lies in the central longitudinal plane of the two- wheeled vehicle, which also corresponds with the centre plane of the front wheel when in its unturned position.

Suspension travel of the front wheel, as in response to road shocks, is in a generally vertical direction with the ball joint end of the kingpin travelling in a similar direction. Where the ball joint, or similar, on which in conjunction with the upper ball joint, or similar, together provide the steering axis, to which they maintain a substantially constant rake angle as a consequence of the quadrilateral construction of the suspension system. Suspension travel of the front wheel is thus accompanied by substantially vertical swinging motion of the outward end of the control arm. The suspension travel may be controlled and dampened by means of several types of dampeners and springing methods that can be adapted to any component of the described suspension system. In a preferred embodiment of this invention, means of dampening and/or springing will attach to the said lower control arm, or can attach to a mechanical linkage relative to the lower control arm, where load and weight from suspension action can be directed towards the body of the two- wheeled vehicle by means of the shock absorption unit/s.

As described above, the control arm is connected to the kingpin for universal movement by means of a ball joint or other equivalent connecting means that allow universal pivotal motion between the kingpin and the control arm. This is necessary in order to allow the front wheel and the wheel axle end of the kingpin to undergo vertical motion in response to road shocks and to also undergo rotational steering motion about the said steering axis that is positioned and orientated much in the same manner as in a conventional design of two-wheeled vehicle. In the preferred embodiment of the invention a conventional handlebar is attached rigidly to the steering strut where this arrangement is connected to the kingpin, and by means of these components steering motion will be applied to the front wheel. Since the primary weight and shock loads on the front wheel are transmitted through the ball joint, or similar, to the control arm then in the direction of the body of the two- wheeled vehicle, the kingpin and the steering strut can be made of lighter construction than could otherwise be obtained in a conventional two-wheeled vehicle. Further, in this preferred embodiment, with the handlebar and steering strut attaching rigidly or when they are integrated with each other, together both can be considered as a single member, with such consideration, there are only three moving members for suspension motion, of which only two of these members are orienting solely for rotational steering motion, where with this lack of complication it can be to the benefit of reduced manufacturing costs thereof, weight saving, and performance in respect of handling plus road-holding ability.

The handlebars, or methods of steering control, can be so configured to have marginal motion in a plane relative to motion of the steering strut where said marginal motion corresponds with ordinary travel of suspension motion, with their connection to the steering strut and/or kingpin and/or front wheel axle to the effect of making the surface encountered by the wheel easier to detect, likewise the amount of grip the front wheel has on the surface, to effect greater 'feeling' with the user. Such can be both a performance and safety advantage, allowing superior road-holding and control of the two-wheeled vehicle. An adequate braking system may be attached to any position of the various described suspension members, or may be attached to the body of the two-wheeled vehicle, and may operate on the wheel, on a wheel hub, on a wheel rim, or on a tyre on the front wheel. Such a braking system may operate on a disc, drum, or any other surface relative to the rotating front wheel.

These aspects of the present invention are set forth in the accompanying drawings of the invention.

DRAWINGS.

Fig 1. An oblige drawing of the front suspension system on a two-wheeled vehicle 1, with the pivoted lower control arm 2, hinged at the body of the two- wheeled vehicle 9. At the other end of the lower control arm is a ball joint 5. Attached to the said ball joint is the kingpin 3, which receives the front wheel axle 10, and pivots in a hinged arrangement 11, with the steering member 4, which extends to the steering head. At the steering head is a second ball joint 6, which is attached to the steering member and to the main body of the two- wheeled vehicle. Handlebars 7, have attachment to the steering strut 4, as in the preferred embodiment of the invention.

Fig 2. A side elevation of the front suspension system on a two-wheeled vehicle 1, with lower control arm 2, kingpin 3, and steering strut 4, with handlebars 7, attached. Shock absorbing unit 8, directed in the vicinity of the body, as in the preferred embodiment of the invention. Lower ball joint 5, and upper ball joint 6, provide the steering axis. Hinged arrangement between the kingpin and steering strut 11, control arm hinges with the body 9, and front wheel axle 10.

Claims

Claims.

1. A front wheel suspension system for a two-wheeled vehicle comprising; a one-sided lower control arm extending forward from a hinged pivot point on the body of the two-wheeled vehicle, having an axis of rotation extending transversely with respect to the longitudinal plane of the lower control arm, a means of universal movement attached to the outward end of said lower control arm, said means of universal movement further attached to a kingpin, said kingpin positioned to receive the front wheel axle, where said kingpin extends outwards from the position receiving the front wheel axle to a hinged pivot point with a steering strut, having an axis of rotation extending transversely with respect to the longitudinal plane of the kingpin, said steering strut extends upwards and backwards from its hinged pivot point to an upper means of universal movement which has attachment to the body of the two- wheeled vehicle, and, a means of manual steering control for the front wheel which has a connection with said steering strut.

2. A front wheel suspension system for a two-wheeled vehicle as in claim 1. further comprising; means of manual steering control can be an integral part of the steering strut, can be attached to the steering strut, or can connect by mechanical means with the said steering strut.

3. A front wheel suspension system for a two-wheeled vehicle as in claim 1, further comprising; means of manual steering control can attach by mechanical means to the kingpin, or to the kingpin and steering strut, or to the kingpin and body, or to the kingpin steering strut and body, or to the front wheel axle, or to the front wheel axle and the kingpin, or to the front wheel axle and steering strut, or to the front wheel axle and body, or to the front wheel axle kingpin and steering strut, or to the front wheel axle kingpin and body, or to the front wheel axle steering strut and body, or to the front wheel axle kingpin steering strut and body.

4. A front wheel suspension system for a two-wheeled vehicle as in claims 1, 2, and 3, wherein means of manual steering control can be positioned close to the said upper means of universal movement.

5. A front wheel suspension system for a two-wheeled vehicle as in claim 1 , further comprising; means of dampening/springing can be attached to at least one of the said suspension members.

6. A front wheel suspension system for a two-wheeled vehicle as in claim 5, further comprising; means of suspension dampening/springing can be attached to a mechanical linkage connected to at least one of the said suspension members.

7. A front wheel suspension system for a two-wheeled vehicle as in claims 5 and 6, wherein the dampening/springing means can operate in compression, tension, bending, torsion or shear mode.

8. A two-wheeled vehicle comprising: a body, a front wheel suspension including; a single-sided lower control arm extending forward from a hinged attachment on the said body, having an axis of rotation extending transversely in respect to the longitudinal plane of the lower control arm, said lower control arm has further attachment to a kingpin by a means of universal movement, where said kingpin is positioned to receive the axle for the front wheel and extends outward of the axle position to where it is hinged with a steering strut, where swinging motion of these two members is in a transverse axis in respect to longitudinal plane of said kingpin, steering strut extends upward and backwards from the hinged pivot point towards the body of the two-wheeled vehicle to which there is attachment by an upper means of universal movement, and, a means of manual steering control for the front wheel having a connection with said steering strut.

9. A two-wheeled vehicle as in claim 8, further comprising; at least one means of suspension dampening/springing attached to at least one said member of the suspension.

10. A two-wheeled vehicle as in claim 9, further comprising; at least one means of suspension dampening/springing attached to a mechanical linkage connected to at least one said member of the suspension.

11. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can attach rigidly with said steering strut.

12. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with said kingpin.

13. A two- wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with said kingpin and said body.

14. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with said kingpin and said steering strut.

15. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with said kingpin said steering strut and said body.

16. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle.

17. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle and kingpin.

18. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle and steering strut.

19. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle and body.

20. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle kingpin and steering strut.

21. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle kingpin and body.

22. A two-wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle steering strut and body.

23. A two- wheeled vehicle as in claim 8, wherein means of manual steering control can have a connection with the front wheel axle kingpin steering strut and body.