GB2154677A

GB2154677A - Unidirectional coupling device

Info

Publication number: GB2154677A
Application number: GB08503335A
Authority: GB
Inventors: Mario Jona
Original assignee: SFV SOC FINANZ VICENZA SpA
Current assignee: SFV SOC FINANZ VICENZA SpA
Priority date: 1984-02-08
Filing date: 1985-02-08
Publication date: 1985-09-11
Also published as: FR2559223A1; GB8503335D0; JPS60249739A; ES8601779A1; ES540205A0; DE3503737A1; IT8419506A0

Abstract

A unidirectional coupling device, comprises: a driving element (1) and a driven element (2) which are coaxially mounted and relatively rotatable and a set of balls (3) forming rolling connection elements. The balls (3) are interposed between axially facing surfaces of said driving and driven elements and are housed in races (4) which are inclined both radially and axially with respect of said surfaces. The device may be used in association with the hand control lever of a bicycle with change-speed gears. <IMAGE>

Description

SPECIFICATION Unidirectional front coupling device The present invention relates to an improved unidirectional coupling device, which can be used in a wide range of applications.

The present invention also concerns one of these applications, namely a hand control lever for bicycle change-speed gears- adopting said device.

As known, the traditional unidirectional coupling devices, whether they are sprag, radial roller or other types of devices, comprise a large number of parts, or else, in order to work properly, they have to be machined with very close tolerances, or else still, they are apt to operate the coupling only in a finished number of positions.

Such devices are therefore costly and scarcely suited for miniaturization, whereby they cannot find convenient use in many applications.

The present invention relates to a device, which performs the unidirectional coupling function and is, at the same time, of simple construction, of reliable working, of easy miniaturization and capable to operate the coupling in any position.

As known, the unidirectional coupling devices of known technique are essentially formed of a driving element, of a driven element and of a third element, interposed between the first two and apt to connect them. Said third element can consist of a sprag, or of one or more rolling elements, as rollers or balls.

In this last case, the connection is all the more efficient, the deeper the rolling elements wedge in between the two driving and driven elements; that is-in the known radial coupling devices-the smaller the angle a' in Fig. 1 of the accompanying drawings, which actually illustrates a coupling of this type. As seen herein, the rolling element is interposed between the driving element and the driven element, along the radius passing through the common centre.

Since-as shown in Fig. 1-said angle a' depends on the dimensions of both the slot housing the rolling element and of the element itself, as well as on the distance between the two driving and driven elements to be connected, it is essential for the working tolerances for this coupling to be very close.

It has now been noticed that this requirement, which often reduces the possibilities of application of the heretofore described devices and which always increases the cost thereof, does not exist when the device is realized as a front type coupling, namely by interposing one or more rolling elements between axially facing surfaces of the driving element and of the driven element, one or more special inclined races being obtained in one of said two elements for housing said rolling elements, according to the diagram of Fig. 2 of the accompanying drawings. In fact, as clearly shown by this diagram, in such an arrangement the angle a is independent from the dimensions of both the rolling element and the slot for housing the same, and it does not either depend on the distance between the elements to be connected.

A unidirectional front coupling device, realized according to the diagram of Fig. 2, will therefore be easier and more economic to construct, and will have the widest possibilities of application.

The present invention actually concerns a device of this type and, more precisely, a unidirectional coupling device of the type comprising a driving element and a driven element, in reciprocal rotation, and one or more rolling connection elements, characterized in that, said rolling connection elements are interposed between axially facing surfaces of said driving and driven elements, and are housed into races inclined in respect of said surfaces. Preferably, said races are obtained in one of said surfaces, inclined both radially and axially.

The invention also concerns a hand lever for the control of bicycle change-speed gears, which makes use of the heretofore defined front coupling device.

The invention is now described in further detail, by mere way of example, with reference to the accompanying drawings, in which: Figure 1 shows, as mentioned, the diagram of a known type unidirectional radial coupling device; Figure 2 shows, as mentioned, the diagram of a unidirectional front coupling device, illustrating the concept on which the present invention is based; Figures 3 and 4 are, respectively, a section view and a plan view of a practical embodiment of the device according to the invention, illustrating one of the driving or driven elements together with the rolling elements cooperating therewith; and Figure 5 is an axial section view of a hand lever for the control of a bicycle change-speed gear, incorporating the device according to the invention illustrated in Figs. 2 to 4.

With reference to Figs. 2 to 4, the device according to the invention comprises a driving element 1 and a driven element 2. formed of coaxial and reciprocally rotating cylindrical flattened bodies, as well as rolling ball elements 3 interposed between said elements 1 and 2. According to the invention, the ball elements 3 are each housed into a race 4 of the driving or driven element, for instance of the driven element 2, which race is obtained on the surface facing the other element, for instance the driving element 1, and is inclined both radially (see Fig. 4) and axially (see Fig.

3). Light springs 5 can be housed into the races 4, for pushing the rolling elements 3 out of said races towards the driving element 1. However, such springs are not indispensable and could be left out.

When the device is in operation, the driving element 1 freely rotates in one direction, in that it tends to move the rolling elements 3 towards the deepest part of the races 4, against the action of the springs 5 or of the mere load of the balls 3. In this case, no motion is hence transmitted to the driven element 2.

Where, when said driving element 1 rotates in the opposite direction, the balls 3 are urged-thanks also to the action of the spring 5 or of the load-to move towards the less deep part of the races 4 and to quickly wedge in against the driven element 2, thereby imparting to the same the desired rotation.

As said, the invention also concerns the application of the coupling device of Figs. 2 and 4 to a hand control lever for bicycle change-speed gears.

With reference to Fig. 5, said hand lever comprises a body 6, made in one piece with a control lever 7, forming the driving element of the coupling, a splined ring 8, forming the driven element, and some balls 9 (only one being illustrated), forming the rolling connection elements of the coupling.

The splines 10, obtained in the ring 8 for housing the balls 9, are inclined both radially and axially and form races which are similar to the races 4 of the device described with reference to Figs. 2 to 4.

The hand lever body 6 and the splined ring 8 are mounted coaxial, the first rotatable on the second and this latter rotatable on a pin 11 to be fixed to the bicycle frame.

The movements of the ring 8 are braked, through a friction washer 12, by a pressure bushing 1 3 onto which a spring 14 acts with adjustable force by screwing more or less tightly the pin 1 5 of a pressure plate 16, thanks to a ring 17.

When using the change-speed gear, the hand lever body 6,-while controlling the displacement of the transmission chain from the smaller to the larger diameter sprockets-freely rotates on the splined ring 8, thus subjected only to the resistance opposed by the spring of the change-speed gear. Whereas-when controlling the transmission chain displacement from the larger to the smaller diameter sprockets-the hand lever body 6 is engaged by the balls 9 which wedge into the bottom of the splines 10, so as to rotate together with the splined ring 8. On this latter acts the resistance of the friction 12, 13, adjustable by means of the ring 1 7.

This device has all the advantages of hand control levers for bicycle change-speed gears with unidirectional coupling. It in fact annihilates the resistance of the friction during control of the transmission chain displacement from the smaller to the larger diameter sprockets, while offering said resistance during control of the transmission chain displacement from the larger to the smaller diameter sprockets: hence, the strength required to operate the hand lever for displacement of the transmission chain in either directions, is practically constant. In fact, during displacement from the smaller to the larger diameter sprockets, the force on the hand lever will have to oppose only the resistance of the spring the change-speed gear, while during displacement from the larger to the smaller diameter sprockets, it will have to oppose only the friction resistance of the hand level, said resistances being almost alike. This determines an easier and more precise control. In addition to these advantages, already present in the known devices, the heretofore described hand lever provides the advantages of the unidirectional coupling devices according to the invention, namely simplicity and economy in construction, as well as excellent functional capabilities.

Claims

1. Unidirectional coupling device, of the type comprising a driving element and a driven element, in reciprocal rotation, and one or more rolling connection elements, characterized in that, said rolling connection elements are interposed between axially facing surfaces of said driving and driven elements and are housed into races inclined in respect of said surfaces.

2. Unidirectional coupling device as in claim 1, wherein said races are obtained, inclined both radially and axially, in one of said surfaces.

3. Unidirectional coupling device as in claim 1, wherein the rolling connection elements are rollers.

4. Unidirectional coupling device as in claim 1, wherein the rolling connection elements are balls.

5. Unidirectional coupling device as in claims 1 to 3, wherein said rolling connection elements are pushed towards the narrower part of the race by elastic elements.

6. Unidirectional coupling device as in claim 1, wherein three rolling connection elements and three races are provided at an even distance and with a uniform radial inclination.

7. Hand control lever for change-speed gears of bicycles, equipped with a unidirectional coupling device as in claims 1 to 5.

8. Hand control lever as in claim 7, comprising a body in one piece with a control lever and a splined ring, said body and said ring being mounted coaxial and rotatable, with interposed balls housed into races of the splined ring, to form a unidirectional coupling device as in claims 1 to 5, said splined ring being mounted rotatable on a pin to be fixed on the bicycle and being opposed to rotation by adjustable friction means.