IE20100034A1 - A front suspension system for two wheeled vehicles, namely bicycles and motorcycles. - Google Patents

Abstract

A bicycle or motorcycle front wheel suspension comprising of three main structural components; a control arm extends forward from a pivot point on the vehicle body to have a ball joint, or similar means of universal movement, attached at its outward end. Said ball joint further attaches to a fork member where a lower portion extends down to receive the front wheel axle and an upper portion extends out and upward to a pivot point with a steering strut. Said steering strut extends back to attach to the vehicle body by means of an upper means of universal movement. Handlebars connect with the steering strut and a means of suspension dampening/springing attaches with the control arm. Suspension action has reduced frictional resistance and the vehicle body can be of lighter construction compared to telescopic fork designs.

Description

A FRONT SUSPENSION SYSTEM FOR TWO-ψΗΕ BICYCLES AND MOTORCYCLES.

DESCRIPTION OF THE INVENTION.

Background of the invention.

ELY The invention disclosed herein is generally related to single-track two-wheeled vehicles. More particular, the present invention is related to the suspension for the front wheel of two-wheeled vehicles, namely bicycles and motorcycles.

Modem 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 bicycle or motorcycle. The spindle 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 bicycle and motorcycle design for many years. Nevertheless, the conventional fork design suffers from certain disadvantages which have long been recognised but never been completely overcome.

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 inward from the front wheel spindle 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 inward from the front wheel. However, the weight load of the vehicle is purely vertical. If the fork is raked, this results in a lateral stress and consequent frictional resistance to suspension travel. Bicycle and motorcycle design and style is further disadvantaged by telescopic forks because the steering geometry IE 10 00 34 and front suspension travel are intertwined therefore restricting changes in frame design when it may be desirable to alter this out with existing design constraints.

As a general design principle, it is desirable that weight and road loads be transmitted 5 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 to have the most direct connection between the front wheel spindle and the mechanisms used for steering the front wheel. 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 steering motion and suspension action.

In view of these objectives, it will be recognised that one disadvantage of the forktype suspension system is that the load path from the front wheel to the frame of the bicycle or motorcycle 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 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.

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

In this regard, it is a more specific objective of this invention to provide in a two30 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 vehicle body that is low and close to the centre of gravity of the vehicle.

JE 1 0 00 34 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 with as few moving components as possible so to reduce manufacturing costs thereof and enhance performance thereof.

It is a further objective of this invention to provide in a two-wheeled vehicle a front 10 suspension and steering system that can utilize a lighter design of vehicle body/frame.

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 front suspension system of at least three main components incorporating an upper quadrilateral construction with the body of the two-wheeled vehicle in conjunction with an extending lower structural fork portion to support the front wheel. The suspension system includes a 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 control arm is a ball joint, or similar means of universal movement, where said ball joint, or similar, further attaches to a pivoted fork member. This control arm is hinged with the body of the vehicle having an axis of rotation extending transversely in respect to the longitudinal plane of the said control arm.

This said lower ball joint, or similar, lies in the central longitudinal plane of the two30 wheeled vehicle, which also corresponds with the centre plane of the wheel when in its unturned position. The front wheel is positioned below said ball joint, or similar means of universal movement.

JE 1 0 0 0 3 4 The pivoted fork member is connected to the control arm by means of this ball joint, or similar, extending to a position below this to receive the front wheel spindle. Said fork extends down either side of the front wheel to receive both ends of the front wheel spindle where it protrudes out from either side of the centre of the front wheel.

This fork is further hinged at its upper end with the steering strut, having an axis of rotation extending transversely in respect to the longitudinal plane of the said steering strut, where this pivot point is positioned somewhere vertically above the front wheel but at a substantial distance from the front wheel and at a position outward and upward of the said lower ball joint, or similar. This hinge axis of the fork plus the front wheel spindle 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. Said steering strut extends inwards from its attachment at the pivot point with the fork to where there is attachment to a second ball joint, or similar means of universal movement, and is further attached onto the body of the two-wheeled vehicle by means of this upper ball joint, or similar, where this area can be considered the steering-head.

Handlebars, or other methods used for manual steering control of the front wheel, are an integrated part of, attached to, or connected to by mechanical means, the said steering strut. 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 joint/steeringhead and will have marginal motion corresponding with suspension motion of the said steering strut.

The said upper ball joint, or similar means of universal movement, 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 and inward direction with the fork member travelling in a similar direction. Where the lower ball joint, or similar, 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 upper quadrilateral construction of the IE 1 0 0 0 34 suspension system. The upper ball joint, or similar, with its attachment to the body of the two-wheeled vehicle and the pivot point for the control arm on the vehicle body are set sufficiently apart to reduce the leverage effect from the front suspension members on the body of the two-wheeled vehicle where the supporting body/framework can be made of a lighter construction than could otherwise be obtained with a bicycle or a motorcycle equipped with telescopic forks. Suspension travel of the front wheel and fork is thus accompanied by substantially vertical swinging motion of the outward ends of both control arm and steering strut. 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 control arm, or can attach to a mechanical linkage which has at least one pivot point on the body of the two-wheeled vehicle and is connected to and controlled by the 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 fork member for universal movement by means of a ball joint, or other equivalent connecting means that allow universal pivotal motion between the fork and control arm, and the steering head is also connected to the steering strut for universal movement by means of a ball joint, or other equivalent connecting means that allow universal pivotal motion between the steering head and steering strut, where both allow universal movement. This is necessary in order to allow the front wheel fork and steering strut 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 bicycle or motorcycle. In the preferred embodiment of the invention a conventional handlebar is attached rigidly to the steering strut in a position close to the upper ball joint, or similar, where this arrangement is connected to the fork, and by means of these three 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 fork and the steering strut can be made of lighter construction than could otherwise be obtained in a conventional bicycle or IE 1 0 00 34 motorcycle. Further, 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 vehicle propulsion handling and road-holding ability.

An adequate braking system may be attached to any position of the various described 10 suspension members, or may be attached to the body of the two-wheeled vehicle, where such a braking system may operate on a disc, wheel rim, drum, tire, or any other surface relative to the rotating front wheel.

These aspects of the present invention are set forth in the accompanying drawing of 15 the invention.

DRAWING.

Fig 1. A side elevation of the front suspension system on a two-wheeled vehicle 1, with control arm 2, fork 3, and steering strut 4, with handlebars 7, attached. Lower ball joint 5, and upper ball joint 6, provide the steering axis. Hinged arrangement between the fork and steering strut 11, control arm hinges with the body 9, front wheel spindle 10, and two-wheeled vehicle body 8.

Claims (8)

1. The invention for which patent protection is claimed is defined as follows;

1. A front wheel suspension system for a two-wheeled vehicle comprising; a fork member positioned to receive the front wheel spindle extending upward from this position to attach to a lower means of universal movement, then extending upward and outward of this position to a pivot point which hinges with a steering 10 strut, having an axis of rotation extending transversely in respect to the longitudinal plane of the said steering strut; said lower means of universal movement has further attachment to a control arm; said control arm extends inwards of this attachment to a pivot point which hinges with the vehicle body, having an axis of rotation extending transversely in respect to the 15 longitudinal plane of the said control arm; said steering strut extends inwards of the pivot point with said fork member to attach to an upper means of universal movement; said upper means of universal movement has further attachment with the vehicle body; 20 a means of dampening/springing has a connection with at least one of the said suspension members; and, a means of manual steering control is connected to the said steering strut.

2. A front wheel suspension system for a two-wheeled vehicle as claimed in claim 1 25 including attachment of dampening/springing means with said control arm.

3. A front wheel suspension system for a two-wheeled vehicle as claimed in claim 1 including attachment of dampening/springing means to a pivoted mechanical linkage which has a connection with said control arm.

4. A front wheel suspension system for a two-wheeled vehicle as claimed in any preceding claim wherein dampening/springing means can operate in compression, tension, shear, bending or torsion mode. IE 1 0 00 34

5. A front wheel suspension system for a two-wheeled vehicle as claimed in claim 1 wherein means of manual steering control is positioned close to said upper means of universal movement. 5

6. A two-wheeled vehicle with a suspension system for the front wheel including; a vehicle body; a front wheel suspension system comprising; a fork member positioned to receive the spindle of the front wheel extending upwards to a means of universal movement, which has further attachment to a control arm, and 10 then extends outwards and upwards of this position to a hinged pivot point with a steering strut; said steering strut extends inwards to a means of universal movement, which has further attachment to the said vehicle body; said control arm extends inwards of its attachment with a means of universal 15 movement to a hinged pivot point on the said vehicle body; a means of dampening/springing has a connection with at least one of the said suspension members; and, means of manual steering control has a connection to the said steering strut. 20

7. A two-wheeled vehicle with a suspension system for the front wheel as claimed in claimed 6 including dampening/springing means has an attachment with the said control arm.

8. A two-wheeled vehicle with a suspension system for the front wheel as claimed in 25 claim 6 including dampening/springing means has an attachment with a pivoted mechanical linkage which is connected to the said control arm.