WO2003062039A1

WO2003062039A1 - Bicycle joint

Info

Publication number: WO2003062039A1
Application number: PCT/NL2003/000051
Authority: WO
Inventors: Cornelis Jan Versluijs
Original assignee: Cornelis Jan Versluijs
Priority date: 2002-01-24
Filing date: 2003-01-24
Publication date: 2003-07-31
Also published as: NL1022356C2

Abstract

The invention relates to a joint provided with a first body (9) and a second body (10) accommodated therein. The first body (9) and the second body (10) are essentially cylindrical, flexible members (13) being fitted between the first body (9) and the second body (10). These flexible members (13) are fitted so as to be pretensioned on rotation of the second body (10) with respect to the first body (9). The internal radius of the first body (9) is essentially greater than the external radius of the second body (10). The joint (1) according to the invention is particularly suitable for use in the vicinity of the crank axle (3) of a cycle. The resilience characteristics can be adjusted in various ways.

Description

BICYCLE JOINT

The invention relates to ajoint provided with a first body and a second body accommodated therein, the first and the second body being essentially cylindrical, flexible members being fitted between the first and the second body, said flexible members being fitted so as to be pretensioned on rotation of the second body with respect to the first body.

Joints of this type are known in the state of the art. Ajoint is known that has a first body that is square in shape and a second body, that is likewise square in shape, accommodated in said first body, turned through an angle of approximately 45°. Resilient components are positioned in the gap between the four sides of the square that forms the second body and the four corners of the square that forms the first body. When the second body rotates relative to the first body, the resilient components drive the second body back into a starting position. In this way the rotation of the second body is counteracted by the resilient components.

Ajoint of the type described above is used in a shaft construction of, for example, caravans.

In the joint according to the state of the art a gap remains between the second body and the first body, so that the second body is still able to move within the first body to some extent. This prevents proper functioning of the joint and is therefore disadvantageous. EP 0 947 417 A2 furthermore also discloses ajoint device which consists of two cylindrical bodies. The two cylindrical bodies have a relatively large difference in diameter. The largest of the two has a cylindrical recess, the internal diameter of which is greater than the diameter of the smaller cylindrical body. Projections oriented outwards have been formed on the outer surface of the smaller body and projections oriented inwards have been formed on the inner surface of the cylindrical opening in the outer body. The radius of the projections of the inner body is approximately equal to the internal radius of the outer body. The internal radius of the projections on the outer body is approximately equal to the radius of the inner body. The projections of the two bodies are so positioned and sized that the inner body can be accommodated in the outer body with a tight fit. The gap between the projections and the inner and outer body is filled with elastic components, h this way the inner body is able to rotate resiliently in the outer body.

However, the device has the disadvantage that the two bodies touch one another. The mutual guiding of the two bodies takes place at the tops of the respective projections. When the joint is placed under load the projections can deform and thus adversely affect the guiding. As a result of the contact between the various components, the joint will wear rapidly. Because, viewed tangentially, the projections overlap one another a jolting effect will be able to occur since the elastic components are completely surrounded by rigid components.

Furthermore, it is not possible to fit or replace the elastic components without dismantling the entire joint device. Adjustment of the resiliency of the joint is thus not easy. One aim of the present invention is to provide a j oint of the type mentioned in the preamble where the first body is not able to come into contact with the second body.

The aim of the present invention is achieved by means of ajoint of the type described in the preamble, characterised in that the internal radius of the first body is essentially greater than the external radius of the second body. In this way the bodies are prevented from coming into contact with one another. With ajoint of this type it is thus not possible for wear to arise as a result of contact between the first and second body. On rotation of the second body in the first body the flexible members are compressed, so that the rotary movement is counteracted.

A further aim of the present invention is to provide ajoint, the resiliency of which can easily be set by a user.

This aim of the present invention is achieved by means of a joint provided with a first body and a second body accommodated therein, flexible members being fitted between the first and the second body, said flexible members being fitted so as to be pretensioned on rotation of the second body with respect to the first body, characterised in that the flexible members have a hole for accommodating a tensioning element, the hole being made such that the flexible member expands radially when the tensioning element is accommodated. The joint according to the invention is, in particular, intended for a sprung rear wheel suspension in a two-wheeler, such as a bicycle.

A tensioning element can be accommodated in the hole in the flexible member. The tensiomng element ensures that the flexible member expands radially. In this way the resiliency of the joint element can be set. Preferably, the tensioning element is so constructed that the resiliency can be adjusted in a simple manner, for example by tightening a bolt or a socket screw in the hole. As a result the pretension in the flexible member increases. Tightening a bolt in the flexible member has the result that the flexible member expands in the radial direction. The flexible member comes into contact with the walls of the grooves, as a result of which pretensioning is produced. As a result of the increase in pretensioning the resiliency of the assembly of the flexible member and the tensioning element increases. Other embodiments of tensioning elements will be discussed further below.

According to one embodiment of such ajoint according to the invention, the joint has at least one tensioning element having a diameter greater than that of the hole. Specifically, a tensioning element of this type will stretch the diameter of the hole, which results in radial expansion of the flexible material.

More preferentially, the present invention is characterised in that the first body and the second body are provided with grooves for accommodating the flexible members and the grooves of the second body adjoin the grooves in the first body, the grooves together enclosing a channel essentially in the shape of a cylinder. By making grooves for accommodating flexible members, the flexible members do not shift between the first body and the second body, whilst good resilient action is still ensured. The flexible members are held in place by accommodation in the grooves. The bodies are preferably so stiff that the degree of deformation is small and guiding is still ensured.

Preferably, at least part of the circumference of the second body that adjoins the first body is made of a low-friction material, for example nylon. The term low-friction material is used to refer to a material that has a low frictional resistance. Wear is prevented from occurring between the two bodies as a result of the use of a low-friction material between the first and the second body.

In a further embodiment the invention is characterised in that the flexible members are made of a flexible material, for example a rubber or elastomer. Narious types of flexible material can be fitted in the grooves produced. If a suspension has to be relatively hard, a rubber composition having a high resilience is chosen. If, however, a suspension has to be relatively soft, a rubber composition having a low resilience is chosen. Flexible materials, such as a rubber, have good resilient properties and are therefore also particularly suitable as production material for the flexible components. Flexible members of different material composition can be placed in the various grooves. It is also possible to provide only some of the grooves with a flexible member. As a result the resiliency of the joint can be set. The invention can furthermore be characterised in that the joint is covered by a closing wall on an axial side. The use of a closing wall prevents the ingress of dirt into the space between the first and the second body. The construction of the joint is also protected against outside influences.

The invention furthermore relates to a two-wheeler, for example a bicycle, provided with ajoint according to the invention. The joint according to the invention can be fitted around the crank axle. As a result the distance between the axes of the sprockets remains constant. A chain that links the two sprockets to one another can then be tensioned more precisely between the two sprockets. Of course, it is possible to fit the joint in other positions, such as, for example, in the front fork of a two-wheeler. Preferably, the two-wheeler is characterised in that the crank axle is fitted in the second body. As a result the distance between the axis of the crank axle and the axis of the drive shaft of a wheel remains constant. When the wheel is driven the tension in the drive chain will not vary as a result of the relative movement of the axis of the crank axle and the axis of the drive shaft. As a result the chain can be tensioned more precisely, which results in a better transfer of force.

Preferably, the two-wheeler is characterised in that the second body is rigidly joined to a rigid arm for holding a wheel and fixing the first body in the second body in the axial direction. The front wheel suspension or the rear wheel suspension can be constructed using ajoint according to the present invention. A wheel suspension could then be constructed in accordance with the 'swing arm' principle. By fixing the first body in the second body in the axial direction, shifting of the second body within the first body is prevented. When a force in the axial direction is exerted on the joint no play is produced, but the second body is restrained.

In a further embodiment the rigid arm for holding a wheel is provided with openings to enable the flexible members and/or the tensioning elements to be inserted and removed. As a result a user can easily replace the flexible members by new members or, for example, by flexible members having different resilience characteristics.

The invention furthermore relates to a method for the production of a first and/or second body of a joint according to the invention. This method is characterised in that the first and/or second body is produced from an extruded section. The first and the second body of the joint can advantageously be produced by extruding, for example, a metal material. By means of the extrusion process both the first body and the second body can be provided with grooves, so that no additional operations are required to make these grooves in the first or second body.

After extrusion, the extruded product is cut to the desired length, which desired length corresponds to the width of the desired joint. If aluminium is used as the material for extrusion, a saving in weight can be achieved compared with conventional materials such as steel, which is advantageous in particular when using ajoint in two-wheelers.

One embodiment of the joint according to the present invention is described in more detail with reference to the figures shown in the drawing. In the drawing:

Fig. 1 shows a perspective view of the joint according to the present invention, the crank axle being housed in the j oint;

Fig. 2 shows a side view of the joint; and

Fig. 3 shows an exposed perspective view of the joint.

Fig. 1 shows a perspective view of the joint 1 according to the present invention, the crank axle 2 being housed in the joint. A crank axle 2, to which the crank 8 is connected, is fitted axially through an opening 3 in the joint 1. The housing part 4 of the joint 1 is fixed to the frame 5 of a cycle. The joint 1 is enclosed at the sides with the aid of the frame sections 20, by means of which the joint 1 can be connected to, for example, the rear wheel of the cycle. Fig. 1 furthermore shows a closing wall 6 that can be fixed to the frame sections 20. The closing wall 6 seals off the joint components that protrude through the frame section 20. The closing wall can be fixed to the joint 1 by means of bolts 7. The frame sections 20 thus form self-supporting arms extending from the joint 1, which arms can optionally be supported, but are not rigidly supported.

Fig. 2 shows a side view of the joint 1. The joint 1 comprises a first body 9 and a second body 10 accommodated therein. The first body 9 has a circular cross-section and an essentially circular opening 15 in the axial direction. The second body 10 has an essentially circular cross-section. The internal radius of the circular opening 15 in the first body 9 is essentially greater than the external radius of the second body 10, so that the first body 9 can accommodate the second body 10. The entire assembly of the first body 9 and the second body 10 is joined to a housing section 4 of the frame 5. Grooves 12 for accommodating flexible components 13 are provided on that side of the first body 9 that faces the second body 10. Grooves 14 for accommodating flexible components 13 are also provided on the outer circumferential side in the second body 10. The grooves 12 and 14 are positioned opposite one another in order to accommodate the flexible components 13. Flexible components 13 having a different material composition can be accommodated in the grooves 12 and 14. As a result the resiliency of the joint can be set. It is also possible not to provide all grooves with a flexible component 13, so that the adjustability can also be achieved by placing or not placing a flexible component 13 in the grooves 12, 14.

Low-friction materials 16 are placed in the opening 15 between the first body 9 and the second body 10 to make it possible for the two bodies to slide smoothly over one another. The low-friction materials 16 are positioned recessed in the second body 10 and in the opening 15 are in contact with the wall of the first body 10. The low-friction materials 16, which, for example, consist of nylon strips, are somewhat rounded on the side facing the first body 9 so that they are in good contact with the wall of the first body 9.

The flexible components 13 are of elongated shape and contain a hole 17 for accommodating a tensioning element 21 shown in Fig. 3. By tensioning the tensioning element 21 the flexible component 13 is pretensioned because the entire space in the grooves 12, 14 is filled. Greater pretensioning of the flexible components 13 results in higher resiliency of the joint 1. The hole 17 and the tensioning element 21 preferably have around cross-section, but can, of course, also be of a different shape.

The tensioning element 21 can also be made up of two separate parts that are pushed into the hole 17 on either side. The two parts of the tensioning element 21 meet one another in the hole 17 and can be joined to one another by means of a screw construction. For this purpose one of the parts will be provided with a screw thread and the other part with means for accommodating a screw thread. The two parts of the tensioning elements 21 are made with a widening at the ends facing outwards, which widening cannot be accommodated by the hole 17 and thus bears against the end face of the flexible component 13. In this way the tensioning element 21 is held in position after fitting. If the two parts of the tensioning element 21 are screwed further into one another with the aid of the screw thread, the widenings will compress the flexible component 13 at the end face and expand this component in the radial direction. In this way the pretension in the flexible components 13 can be influenced and the resiliency of the joint 1 can be set. This embodiment of the tensioning elements 21 is, however, not equally effective for all applications. If, for example, the joint 1 is used in a compact manner around the crank axle of a bicycle, the flexible components 13 will have to be made of such a stiff material that it will not expand in the radial direction to a sufficient extent by means of exerting a force on the end face.

In another embodiment the tensioning element 21 has a diameter that is greater than the internal diameter of the hole 17. In this case the flexible material 13 will be pretensioned by inserting the tensioning element 21. Specifically, the diameter of the hole 17 will be stretched, which results in radial expansion of the flexible material 13. The resiliency of the joint 1 can be determined by the selection of the diameter of the tensioning element 21. A user can adjust this resiliency in a simple manner by replacing the tensioning elements 21 by tensioning elements 21 of a greater or smaller diameter, depending on the desired resiliency. The resiliency can also be changed by using different tensioning elements 21 that have the characteristic of causing the flexible component 13 to expand in the radial direction when they are accommodated in the hole 17.

The second body 10 is provided with holes 18 for fixing frame sections 20 to the second body 10. As can be seen in Fig. 3, the frame sections 20 are provided with holes 22 for fitting the closing wall 6, for example with the aid of bolts 7. This closing wall 6 prevents the ingress of dirt and the like into the space between the first body 9 and the second body 10 and the other components of the joint 1.

Preferably, the frame sections 20 are provided with openings through which the flexible elements 13 and/or the tensioning elements 12 can be inserted in and removed from the joint. It is then not necessary to dismantle the joint 1 in order to replace these elements.

The second body 10 is furthermore provided with a central opening 19 to allow the drive shaft, for example a crank axle (not shown) to pass through.

Fig. 3 shows an exposed perspective view of the joint 1 according to the present invention. The joint 1 comprises a first body 9 and a second body 10 positioned therein. Both bodies 9, 10 are accommodated in a housing 4, which can be fixed to a frame. The second body 10 is fixed to the rear wheel suspension 20 so that the entire rear wheel suspension is resiliently fixed to the joint 1.

The crank axle 3 is positioned in the opening 19 in the second body 10. The second body 10 is able to rotate about the axial axis of the crank axle 3. The second body 10 rotates within the first body 9 about the axial axis of the same crank axle 3. Guide members, for example in the form of a low-friction material 16, such as, for example, nylon, are placed in the space 15 between the first body 9 and the second body 10, which guide members are in contact with both the first body 9 and the second body 10. Flexible components 13 are also positioned in the grooves. To pretension these flexible components 13, the tensioning elements 21, for example in the form of socket screws, can be screwed into the holes 17, as has already been discussed above. The flexible component expands as a result and will be put under pretension in the cavity that is formed by the grooves 12 and 14.

Claims

1. Joint provided with a first body (9) and a second body (10) accommodated therein, the first (9) and the second body (10) being essentially cylindrical, flexible members (13) being fitted between the first (9) and the second body (10), said flexible members (13) being fitted so as to be pretensioned on rotation of the second body (10) with respect to the first body (9), characterised in that the internal radius of the first body (9) is essentially greater than the external radius of the second body (10).

2. Joint provided with a first body (9) and a second body (10) accommodated therein, flexible members (13) being fitted between the first (9) and the second body (10), said flexible members (13) being fitted so as to be pretensioned on rotation of the second body (10) with respect to the first body (9), characterised in that the flexible members (13) have a hole (17) for accommodating a tensioning element (21), the hole (17) being made such that the flexible members (13) expand radially when the tensioning element (21) is accommodated.

3. Joint according to Claim 2, comprising at least one tensioning element (21) having a diameter greater than that of the hole (17).

4. Joint according to one of the preceding claims, characterised in that the first body (9) and the second body (10) are provided with grooves (12, 14) for accommodating the flexible members (13) and the grooves (14) of the second body (10) adjoin the grooves (12) in the first body (9), the grooves (12, 14) together enclosing a channel essentially in the shape of a cylinder.

5. Joint according to one of the preceding claims, characterised in that at least part of the second body (10) that adjoins the first body (9) comprises a low-friction material (16), for example nylon.

6. Joint according to one of the preceding claims, characterised in that the flexible members (13) are made of a flexible material, for example a rubber or elastomer.

7. Joint according to one of the preceding claims, characterised in that it is covered by a closing wall (6) on the axial side.

8. Two- wheeler, for example a bicycle, provided with ajoint according to one of the preceding claims.

9. Two-wheeler according to Claim 8, characterised in that the crank axle is fitted in the second body (10).

10. Two-wheeler according to Claim 8 or 9, characterised in that the second body (10) is rigidly joined to a rigid arm (20) for holding a wheel and fixing the first body (9) in the second body (10) in the axial direction.

11. Two-wheeler according to Claim 10, characterised in that the rigid arm (20) for holding a wheel is provided with openings to enable the flexible members (13) and/or the tensioning elements (21) to be inserted and removed.

12. Method for the production of a joint according to one of Claims 1 - 8, characterised in that the first (9) and/or second body (10) is produced from an extruded section.