WO2008065677A2

WO2008065677A2 - A handlebar assembly

Info

Publication number: WO2008065677A2
Application number: PCT/IN2007/000550
Authority: WO
Inventors: Abraham Joseph; Shrinivas Yalaguresh Umarji
Original assignee: Bajaj Auto Limited
Priority date: 2006-11-27
Filing date: 2007-11-19
Publication date: 2008-06-05
Also published as: PE20081211A1; WO2008065677A3

Abstract

A clip on handlebar assembly comprising: a. a handlebar element having an inner end portion and an outer end portion which is adapted to be gripped by the rider; b. a handlebar mount for mounting the handlebar element; and c. connection means for connecting the handlebar element to the handlebar mount; wherein connection of handlebar mount and handlebar element is made to isolate the handlebar element from vibration transmitted through the connection means. Clip on connection of the handlebar element may be made while isolating an at least predominant portion of the handlebar element from the handlebar holder.

Description

A HANDLEBAR ASSEMBLY

FIELD OF THE INVENTION

This invention relates to a handlebar assembly for use as a steering mechanism for a vehicle.

BACKGROUND TO THE INVENTION

Many different handlebar constructions are available. A particularly convenient form of handlebar construction is of the so-called clip-on type. The clip- on handle bar style is a type of motorcycle handlebar in which two separate handlebar elements are attached directly to the front forks, through handlebar mounts, as opposed to a standard one-piece handlebar attached to the triple tree. The term is often shortened to "clip-on". The individual tubes or handlebar elements of the handle bar are attached or clamped to the front suspension (most commonly in the form of front fork tubes) of a motorcycle. Such a construction is popular, particularly for sport type motorcycles, as it allows more control for the rider and a greater flexibility of adjustment of the handlebars.

However, all handlebars are subject to vibration which may make riding a motorcycle uncomfortable. The clip-on type of handlebar is particularly subject to vibration induced by the engine and transmitted through the vehicle chassis or frame that is connected to the fork tubes. More specifically, the outer portion of the handlebar vibrates due to the transmission through it of vibrational forces from the handlebar holder in which the handlebar element or tube is mounted. A rider may prefer to avoid such a construction of handlebar and other forms of handlebar assembly, in which the outer handlebar portion and its holder are subjected to less engine induced vibrations, may be selected instead.

As the handle-bar assembly is part of the steering mechanism and most commonly also mounts a vehicle braking system, the method of securing the clips- ons is of a prime safety concern. If the handle-bars are not securely fastened, or are perceived by the operator to be insecure or too indirect, the operator may choose not to operate the vehicle for lack of confidence in the system.

To some degree, attempts have been made to provide some isolation damping by providing rubberised hand grips for the operator to hold. However, this method has only limited success.

It is an object of the present invention to provide a clip on handlebar assembly less prone to vibration.

SUMMARY OF THE INVENTION

With this object in view, the present invention provides a clip-on handlebar assembly comprising:

(a) a handlebar element, having an inner end portion and an outer end portion which is adapted to be gripped by the rider;

(b) a handlebar mount for mounting the handlebar element; and

(c) connection means for connecting an inner end portion of the handlebar element to the handlebar mount; wherein connection of handlebar mount and handlebar element is made to isolate the handlebar element from vibration transmitted through the connection means.

Conveniently, the connection means connects an inner end portion of the handlebar element to the handlebar mount while isolating an at least predominant portion of the handlebar element from contact with the handlebar mount. More specifically, the handlebar element and handlebar mount are not in physical contact over a predominant portion of their opposing surfaces, these opposing surfaces being located proximate the connection means. Indeed, connection at the inner end or inner end surface of the handlebar element itself may allow vibrational isolation of the handlebar element from the handlebar mount, particularly if the connection means has vibration damping properties. Such damping properties may be achieved by including a damping material, such as rubber, within the connection means. In this case, a vibration damper may form part of the connection means. By "vibrational isolation" is intended that, in design condition, the handlebar element and handlebar mount do not make contact with each other, either directly or indirectly, over the predominant portion of the handlebar element thus minimising transfer of vibrational forces from handlebar element to handlebar holder. Connection may be made at one inner end of the handlebar element with a vibration damper being located between the handlebar holder and the handlebar element at that inner end. Advantageously, the vibration damper is located between the inner end surface of the handlebar element and an opposed surface of the handlebar mount. The damper reduces vibrational forces acting on the connection means, being transmitted to the handlebar element, and becoming amplified at the outer grip end of the handlebar element. Therefore, because less vibration is transferred to the handlebar element, better rider comfort is achieved.

Preferably, the mounting of the handlebar element to the handlebar mount via the vibration damper is done in such a way that good driver feel is maintained of the vehicle steering. This can conveniently be achieved by using a suitable selected vibration damping material and dimensions.

The handlebar mount may be a holder having a mounting aperture; and the handlebar element, which may be tubular or have tubular portions, may have its inner end portion located within the mounting aperture and an outer end portion accessible to be gripped by the rider. Alternatively, the handlebar element may be mounted over the handlebar mount which has a portion forming a spigot for the handlebar element. In either event, the inner portion of the handlebar element is connected to the handlebar holder by connection means having vibration damping properties.

This assembly vibrational^ isolates the handlebar element from the handlebar holder so as to minimise transfer of amplified vibration forces along the outwardly extending length of the handlebar mount to the outer end portion of the handlebar element. Means may be provided to prevent transmission of vibrational forces in a radial direction from handlebar holder to handlebar tube. To this end, clearance(s) or space(s) may be left between opposing surfaces of the handlebar element and handlebar mount. Such clearance(s) prevent physical contact between handlebar element and handlebar mount over a predominant portion of their opposing surfaces under design conditions. In the case of a tubular handlebar element and handlebar mount or holder, for example comprising a cylindrical mounting aperture and cylindrical handlebar element, such a clearance may take the form of an annular volume or annular gap. One first clearance may extend axially along the length of the handlebar element towards the outer end portion of the handlebar element. A second clearance may be located between the inner end surface of the handlebar element and an opposed surface of the handlebar mount. This opposed surface may form a base of the mounting aperture of the handlebar mount. It may be observed that both clearances are proximate the connection means.

Vibration damping material is preferably not to be inserted in the clearance(s), particularly the first axially extending clearance, as this could assist transfer of vibrational forces from handlebar holder to handlebar element.

In addition, it is preferable that the mounting of the handlebar element, via the vibration damper to the handlebar mount is in a "fail safe" mode in the event that the vibration damper fails or its limits are exceeded. Conveniently, this may be achieved by ensuring that the handlebar element and the handlebar mount are in close proximity to each other and will come into contact with each other in the event that the vibration damper suffers a mechanical failure, or otherwise exceeds its safe operating limits. In this way, excessive relative motion between the handlebar element and the handlebar mount can be avoided both to ensure a fail safe operation and to ensure that good and accurate driver feel of the steering is maintained.

The damped connection means is desirably located at as far inward as possible of a portion of the mounting aperture such that connection between handlebar mount and handlebar element is made at this point. In such manner, the handlebar element is isolated from the handlebar mount providing an optimal reduction of vibration. A vibration damper, including such material, may form part of the connection means and may be configured to isolate handlebar element from the handlebar mount to reduce transmission of vibration.

The vibration damper may have a first portion forming part of a connection or clamping arrangement for connecting handlebar mount and handlebar element; and a second portion of damping material, the two portions being integrally formed within the vibration damper. The first portion of the vibration damper may be provided with serrations to assist frictional engagement with the handlebar mount.

The connection means advantageously allows press-fitting of the connection means into or over the handlebar element. The connection means may then be press fitted through or over the handlebar mount. In such case, the above described vibration damper of the connection means may be a sleeve or silent bush which may be press fitted within the mounting aperture. The handlebar element may then be press-fitted within the silent bush with the bush providing a clearance between the handlebar element and the surface of the mounting aperture. This clearance acts to minimise vibration and its design dimension may be selected with that object in view.

Alternatively, the damping sleeve or silent bush may be arranged such that a handlebar element fits over it, preferably by press fitting a handlebar element over the silent bush. There is provided a clearance between handlebar element and the surface of the mounting aperture. In this way, the connection between holder and handlebar element is made through a vibration damped connection made through the silent bush. Again, the design dimension of the clearance may be selected to minimise probability of contact between handlebar element and mounting aperture surface and consequential transfer of vibration between the two components under normal or design conditions.

The connection between handlebar mount and handlebar element or tube may be made secure through suitable configuration of the connection means, damping element and mounting aperture. For example, the inner end portion of a handlebar element may taper inwardly co-operating with a complementary inward taper of an inner diameter of the damping element where the handlebar element is to be press fitted within the inner diameter of the damping ^"element.^{1 5}If the damping element is a silent bush, the inner diameter of the silent bush tapers inward. This tapered configuration allows a better engagement.

The damping element may have an inner end shaped or fitted with engaging elements to allow better fixity or frictional engagement within the mounting aperture. In particular, the engaging elements may prevent rotation of handlebar tube -clamp assembly where the connection means is a clamp and a handlebar element is a tube. For example, the silent bush may have an inner end and an outer end. The inner end contacting a base wall of the mounting aperture may be provided with serrations, or other frictional engaging means which allows better fixity of the bush/handlebar tube assembly (connection means) within the mounting aperture.

A handlebar element or tube may be connected by connection means secured through an aperture of the handlebar mount or holder, and communicating with a corresponding aperture in the handlebar element, for example by a bolting arrangement. Other connection arrangements may be envisaged.

Conveniently, handlebar elements are of tubular construction as typically used in motorcycles and motor scooters. Although the handlebar construction of the invention is well adapted to use in 2 wheel vehicles such as motorcycles, it could also be used in other vehicles, including 3 wheelers, using handlebars.

The handlebar assembly of the present invention allows the benefit of a clip on fit while minimising vibration and increasing rider comfort. Vibration is damped significantly because the connection between holder and handlebar element is made as close to the inward end of the handlebar element as possible such that vibration is damped and magnification of vibrations along the length of the handlebar avoided. Other than at the point of connection, the handlebar element is designed to be vibrationally isolated from its handlebar mount. BRIEF DESCRIPTION OF THE DRAWINGS

The handlebar assembly of the present invention may be more fully understood from the following description of preferred embodiments thereof made with reference to the accompanying drawings in which:

Figure 1a is a top cross-sectional view of a prior art handlebar assembly;

Figure 1 b is a top cross-sectional exploded view of the handlebar assembly of Figure

1a;

Figure 2a is a top cross-sectional view of a handlebar assembly in accordance with a first embodiment of the present invention;

Figure 2b is a top cross-sectional exploded view of the handlebar assembly of Figure

2a;

Figure 2c is a side view of a damping element used in the handlebar assembly of

Figures 2a and 2b;

Figure 3a is a top cross-sectional view of a handlebar assembly in accordance with a second embodiment of the present invention; and

Figure 3b is a top cross-sectional exploded view of the handlebar assembly of Figure

3a.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to Figures 1a and 1 b, there is shown a handlebar assembly 90 formed in a prior art clip-on type as is particularly convenient for a motorcycle. However, this handlebar assembly 90 is also prone to vibration. Such vibration is caused by transmission of engine induced vibration from the front forks (not shown) of the motorcycle to the handlebar mount or holder 95 and through the connection between the handlebar holder 95 and the handlebar element or handlebar 92.

Handlebar 92 is of tubular construction having an inward portion 92a with outer cylindrical surface 92b. At an inner end 92a of the handlebar 92 is fitted a bush 93. The bush 93 is formed with a threading 93a to accommodate a bolt of a clamping arrangement to be described below. Handlebar holder 95 includes a mounting aperture 97 of cylindrical shape and having a bore 96 at a base end 97a. The mounting aperture 97 has a surface 97b which engages with the handlebar 92 on its connection to the handlebar holder 95.

To connect handlebar 92 to holder 95, the handlebar tube 92 is press fitted into mounting aperture 97 and connected into position by a connection means. The chosen method of connection is clamping. Handlebar 92 is clamped into position using a clamping arrangement of bolt type having threading 94b, mounting bolt 94a and washer 94. Bolt 94a is fitted through the washer 94 and the bore 96 of the mounting aperture 97 and into the threading 93a of the bush 93. Contact between outer cylindrical surface 92b and surface 97b of the aperture may be noted along the inner portion of the handlebar 92. This contact or engagement is valuable in achieving interference fitting but also allows vibrational forces, particularly those induced by the engine, to be transmitted through the clamping arrangement (93, 94, 94a, 94b, 96) to act on the handlebar 92. This engine induced vibration causes rider discomfort.

In Figures 2a and 2b is shown an alternative handlebar assembly 190, according to the first embodiment of the invention. Again, the handlebar assembly is of clip-on type.

Handlebar element or handlebar 192 is also of tubular construction having an inward portion 192a with outer cylindrical surface 192b and an inner end surface 192c, this surface being formed by the wall of tubular handlebar 192 and, consequently, having relatively small cross-sectional area. A bore 192d of the handlebar 192 receives a portion of a silent bush 193. Inward portion 192a tapers outwardly towards inner end 192c.

The inclusion of the silent bush 193 forms another aspect of the invention. Silent bush 193 is formed in two parts. A first part 193d of cylindrical shape is formed with a bore 193a to accommodate a bolt of a clamping arrangement to be described below. This first part 193d may also be a polymeric material having some vibration damping capacity. A second part 193e incorporates a primary damping element. Therefore, unlike bush 93, the silent bush 193 is not a simple cylinder of damping material. The silent bush part 193d has one inner end 193b formed as a flange. The silent bush part 193e is generally cylindrical and encloses a cylindrical insert 193f formed of a damping material such as rubber. This enclosure is formed by a metal skin 193g forming an outer surface of the silent bush. The metal skin 193g may also be formed as a cylinder enclosing the damping element though it may be open at an outer end 193c of the silent bush 193. Inner end 193b, forming a first portion, of silent bush 193 is formed wjth serrations 200 as shown in Figure 2c which are frictional gripping or engagement means.

. Handlebar mount or holder 195 includes a mounting aperture 197 of cylindrical shape and having a bore 196 at a base end 197a. Bore 196 is of lesser diameter than an outer diameter of handlebar 192. The mounting aperture 197 has a surface 197b and a base wall 197c.

Handlebar 192 is connected to handlebar holder 195 by clamping. The silent bush 193 is first press fitted into the bore 192d of the handlebar 192. It is the silent bush which will engage with a' clamping arrangement to allow connection of handlebar 192 to handlebar holder 195.

The handlebar clamping arrangement is again of bolt type having washer 194 and mounting bolt 194a with threading 194c. A cap 194b may be provided for the bolt arrangement enclosing aperture 199 of handlebar holder 195 when connection is finished. Cap 194b may also be formed of a vibration damping material, portion of which may surround the bolt 194a, isolating it from the handlebar holder 195. Such enclosure prevents transfer of vibration between bolt 194a and handlebar holder 195 as well as ingress of water and dirt to the clamping arrangement which may make servicing more difficult. Bolt 194a is fitted through the washer 194 and the bore 196 of the mounting aperture 197 and into the threaded bore 193a of the silent bush 193. The bolt is tightened to clamp the handlebar 192 into position within the mounting aperture 197. As clamping proceeds, serrations 200 come into frictional engagement with the base wall 197c of mounting aperture 197 and connection of handlebar 192 to handlebar 195 is completed.

The connection varies in significant manner from that described in Figures 1a and 1 b to achieve lesser vibration. First, the handlebar 192 is not press fitted within the mounting aperture 197 leaving the handlebar 192 in contact with handlebar holder 195. The outer surface 192b of the handlebar 192 has a clearance C (illustrated in Figure 2a), and taking the form of an annular gap, from surface 197b of the mounting aperture 197 which prevents contact between opposing surfaces 192b and 197b - which contact would enable transmission of a significant degree of vibration of the handlebar 192 - under design conditions. Second, the inner end surface 192c of handlebar 192 is isolated from the opposed base wall 197c of the mounting aperture 197 by an inner end or flange 193a of the silent bush 193 and a further clearance D of the inner end 192c of handlebar 192 from the silent bush flange 193b, this flange having vibration damping properties. Consequently, vibration forces acting on inner end surface 192c are minimised or avoided because handlebar 192 and handlebar holder 195 are vibrational^ isolated from each other. Rider comfort is increased. On the other hand, the benefit of a clip-on type construction is maintained.

In an alternative arrangement depicted in Figure 3a and 3b, the handlebar holder 295 has a mounting aperture 297 of cylindrical construction. Portion 297a has lesser diameter than portion 297b and is arranged on a handlebar side of the handlebar holder 295. Mounting aperture portion 297b has a surface 297c.

The silent bush 293 is also of different construction though having two parts 293a and 293b, each part being of generally cylindrical shape. Part 293b, located outwardly of damping part 293, forms a sleeve for part 293a which is again a silent bush formed of a vibrational^ damping material such as rubber. Silent bush 293a has an inner diameter of tapered cross-section.

Handlebar 292 may also have an inner end 292a of the handlebar 292 fitted with a bush 303. Bush 303 is formed with a threading 303a into which a bolt 294 of a clamping arrangement of nut and bolt type is fitted. The inward taper of handlebar 292 may also be noted. The tapered portion 292a of the handlebar 292 co-operates with the correspondingly tapered inner diameter of silent bush 293.

To connect handlebar 292 to handlebar holder 295, the inner portion 292a of the handlebar 292 is inserted through the mounting aperture and the silent bush 293 is fitted over its inner end. The bolt 294, with a threaded portion 294b is inserted through the washer 294a and then tightened. As the bolt 294 is tightened, the silent bush 293 expands to form an interference fit within mounting aperture portion 297b thus completing connection of handlebar 292 to handlebar holder 295. The handlebar 292 has a clearance from the mounting aperture surface 297c formed by the silent bush 293. The clearance C, in the form of an annular gap, left between the handlebar 292 and the surface 297d of mounting aperture portion 297a may also be noted. This clearance C is designed to avoid physical contact, let alone engagement, between the handlebar 192 and mounting aperture 297 under design conditions. In this manner, the handlebar 292 is vibrationally isolated from the handlebar holder 295 and rider comfort is improved while the benefit of a clip-on handlebar assembly is maintained.

Modifications and variations to the handlebar assembly of the present invention may be apparent to the skilled reader of this disclosure. Such modifications and variations are within the scope of the invention.

Claims

CLAIMS:

1. A clip on handlebar assembly comprising: a) a handlebar element, having an inner end portion and an outer end portion which is adapted to be gripped by the rider; b) a handlebar mount for mounting the handlebar element; and c) connection means for connecting the handlebar element to the handlebar mount; wherein connection of said handlebar mount and said handlebar element is made to isolate the handlebar element from vibration of the handlebar mount transmitted through the connection means.

2. The handlebar assembly of Claim 1 wherein the connection means connects an inner end portion of the handlebar element to the handlebar mount while isolating an at least predominant portion of the handlebar element from contact with the handlebar mount.

3. The handlebar assembly as claimed in any Claim 1 or 2 wherein the connection means has vibration damping properties.

4. The handlebar assembly as claimed in Claim 2 or 3 wherein a vibration damper is located between an inner end surface of the handlebar element and an opposed surface of a mounting aperture of the handlebar mount.

5. The handlebar assembly as claimed in Claim 3 or 4 wherein the handlebar mount is a handlebar holder having a mounting aperture and the handlebar element has its inner end portion located within the mounting aperture and its outer end portion accessible to be gripped by the rider.

6. The handlebar assembly as claimed in any one of Claims 1 to 3 wherein the handlebar element is mounted over the handlebar holder which has a portion forming a spigot for mounting the handlebar element.

7. The handlebar assembly as claimed in any one of the preceding Claims wherein the handlebar element and handlebar mount are not in physical contact over a predominant portion of their opposing surfaces.

8. The handlebar assembly as claimed in any one of the preceding Claims wherein the handlebar element and the handlebar mount are mounted in close proximity to each other.

9. The handlebar assembly as claimed in any one of the preceding Claims wherein a clearance is left between opposing surfaces of the handlebar element and the handlebar mount to prevent physical contact between said opposing surfaces under design conditions.

10. The handlebar assembly as claimed in Claim 8 wherein the handlebar element and handlebar mount are tubular and the clearance left between said opposing surfaces of the handlebar element and handlebar mount is an annular gap.

11. The handlebar assembly as claimed in Claim 9 or 10 wherein the first clearance extends axially along the length of the handlebar element towards the outer end portion of the handlebar element.

12. The handlebar assembly as claimed in any one of the preceding Claims wherein the handlebar element and the handlebar mount are connected leaving a second clearance located between an inner end surface of the handlebar element and an opposed surface of the handlebar mount; and the first clearance located between the axially extending opposed surfaces of the handlebar element and handlebar mount.

13. The handlebar assembly as claimed in any one of the preceding Claims wherein the connection means comprises a vibration damper having a first portion forming part of a clamping arrangement for connecting handlebar mount and handlebar element; and a second portion of damping material, the two portions being integrally formed within the vibration damper.

14. The handlebar assembly of Claim 13 wherein the first portion of the vibration damper is provided with serrations for frictional engagement with said handlebar mount.

15. The handlebar assembly of Claim 13 or 14 wherein the vibration damper is press fitted into or over the handlebar element.

16. The handlebar assembly of Claim 13 or 14 wherein the vibration damper is press fitted through or over the handlebar mount.

17. The handlebar assembly of any one of Claims 13 to 16 wherein the vibration damper is a sleeve.

18. A clip on handlebar assembly comprising a) a handlebar element having an inner end portion and an outer end portion which is adapted to be gripped by the rider; b) a handlebar mount for the handlebar element; and c) connection means for connecting an inner end portion of the handlebar element to the handlebar holder; wherein handlebar mount and handlebar element are vibrational^ isolated from each other at an inner end portion thereof by the connection means.

19. A handlebar assembly substantially as hereinbefore described with reference to Figures 2a to 3b.