FR3003202A1 - FREE WHEEL BODY HUB FREE WHEEL AND CYCLE WHEEL EQUIPPED WITH SUCH HUB - Google Patents

Abstract

This freewheel body (40) of a freewheel hub comprises: - a body (42) comprising assembly means (41), with possibility of unidirectional rotation, with a hub body of the wheel hub; free, - an insert (44) mounted around the body (42) and made from a material different from that of the body (42), the insert (44) having means (44.2) for securing in rotation with a cassette of sprockets. The body (42) and the insert (44) are assembled together by means of complementary assembly means (S42.2, S44A) and by adhesive means.

Description

The invention relates to a freewheel body for a cycle, such as a bicycle, to a free wheel hub, as well as to a freewheel body. to a cycle wheel equipped with such a hub. It is known to equip a cycle with a free wheel hub which allows the drive of this wheel by means of a chain engaged on a cassette of gears, while allowing the cycle to advance, on its momentum, without that the user has to pedal continuously. A free wheel hub generally has a freewheel body mounted around a portion of the hub body, with the possibility of unidirectional rotation. The freewheel body is generally provided with outer splines which cooperate with the gear cassette. When the cyclist pedal, the pinion cassette exerts a force on the grooves which tend to deform plastically by matting. During maintenance, it becomes difficult, if not impossible, to extract the pinion cassette. In order to reduce weight, some freewheel bodies are made from a light metal alloy such as an aluminum alloy, but they are sensitive to matting. Other heavier freewheel bodies are made of steel or titanium and have better resistance to the matting phenomenon. However, their mass and cost are high. EP-A-1 495 879 discloses a free wheel hub for a cycle in which the freewheel body is in two portions. A first portion is assembled to the hub body and comprises, over one part of its length, splines, the other portion being smooth and receiving a removable ring provided with complementary splines. The rotational connection of the two portions of the freewheel body is ensured by the pinion cassette. In case of wear, the removable portion can be replaced. This geometry makes it possible to replace only a part of the surfaces subjected to matting. The torque transmitted by the pinion cassette to the freewheel body can be very important. If the materials and the dimensioning, in particular the thickness, of the mechanical parts constituting the hub are poorly chosen, the latter may undergo deformations, such as, for example, diameter expansions which reduce the clearance between the splines and the gables or contractions of diameter which have the effect of damaging the bearings. It is these disadvantages that the invention intends to remedy more particularly by proposing a new lightweight, economical and easy-to-produce free wheel hub, in which the surfaces subjected to matting are reinforced. The object of the invention is also to provide a hub whose different parts will not undergo deformation in response to the torque transmitted between the pinions and the freewheel body.

To this end, the invention relates to a freewheel body of a freewheel hub, said freewheel body comprising: a body comprising assembly means, with possibility of unidirectional rotation, with a body of wheel-free hub hub, an insert mounted around the body and made from a material different from that of the body, the insert having means for securing in rotation with a pinion cassette. The body and the insert are assembled together by means of complementary assembly means and by adhesive means.

Thanks to the invention, the body of the freewheel body can be made from a light and inexpensive material, such as an aluminum alloy, which is not necessarily resistant to matting. The insert can be made from a material that is more resistant to matting. The overall mass and the cost price of the freewheel body are thus reduced. According to advantageous but non-mandatory aspects of the invention, such a hub may incorporate one or more of the following features taken in any technically permissible combination: the complementary assembly means are constituted by a threading of the body and by a complementary thread of the insert. - A threaded portion of the insert protrudes beyond the body, along a central axis of the freewheel body. - The body is made from an aluminum alloy. - The insert is made from a steel alloy. - The insert is manufactured by bar turning. - The adhesive means consist of glue, including two-component epoxy adhesive or anaerobic monocomponent. - The insert is supported against a shoulder of the body, possibly via a washer. The invention also relates to a freewheel hub, comprising a central shaft defining an axis of rotation, a hub body and such a freewheel body mounted free to rotate about the central shaft. The invention also relates to a cycle wheel comprising such a free wheel hub. The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of a freewheel hub and a freewheel body conforming to its principle, given only by way of example and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a free wheel hub according to the invention; Figure 2 is an exploded perspective view of a freewheel body forming part of the free wheel hub of Figure 1; and Figure 3 is a longitudinal section of the freewheel body of Figure 2, equipped with a pinion cassette. The free wheel hub 2 shown in Figure 1 is part of a bicycle rear wheel whose spokes 4 are shown in their center lines in Figure 1 only, these spokes being mounted on a not shown rim. The hub 2 comprises a hollow shaft 10 whose longitudinal axis X is noted. This shaft 10 carries, at a first threaded end 12, a nut 14. At its second threaded end 16 opposite the end 12, the shaft 10 carries a second nut 18. The nuts 14 and 18 allow the mounting of the hub 2 and the wheel to which it belongs on the not shown frame of a bicycle. In what follows, the terms "axial" and "radial" are defined with respect to the axis X. For example, an axial dimension is measured parallel to the axis X, while a radial dimension is measured in one direction radial with respect to this axis. A hub body 20 is mounted around the shaft 10, with possibility of rotation, relative to the shaft 10, about the axis X. Non-visible ball bearings in the figures are interposed radially between the shaft 10 and the body 20. The hub body 20 has two lateral flanges 22 and 24 on which the spokes 4 are mounted. A freewheel body 40 is assembled with the hub body 20 by means of a gear mechanism. wheel-free known in itself, partially visible in the figures, with the possibility of unidirectional rotation. For example, the freewheel body 40 is provided with notches 41 for receiving pawls, and the hub body 20 is provided with an internal toothing intended to interact with the pawls, for selectively securing the bodies 20 and 40 when the hub 2 is in a so-called pedaling configuration, in which the freewheel body 40 is driving relative to the hub body 20 because the cyclist exerts a driving force in rotation of the freewheel body 40, by means of of a chain not shown. The pawls allow a unidirectional rotation of the hub body 20 relative to the freewheel body 40 and do not oppose the rotation of the wheel when the cyclist stops pedaling. The freewheel body 40 is centered on an axis X40 which coincides with the X axis in the mounted configuration of the free wheel hub 2. The freewheel body 40 comprises a body 42 and an insert 44 mounted around the body 42. The body 42 comprises a first zone 42.1 which comprises the notches 41 engaged with the freewheel mechanism. The first zone 42.1 is extended by a second zone 42.2 circular section of smaller diameter than that of the first zone 42.1. An annular shoulder 42.3 perpendicular to the axis X40 is formed between the areas 42.1 and 42.2. The outer surface S42.2 of the second zone 42.2 is threaded and receives the insert 44. The inner surface of the body 42 is like the hub body 20 rotatably mounted on the shaft 10, via one or several rolling bearings 49 or plain bearing.

The insert 44 is generally cylindrical with a circular section, and its inner surface S44A comprises a threading complementary to the thread of the body 42. The inner surface is threaded over its entire length. Optionally, a washer 43 is interposed between the shoulder 42.3 and the insert 44. The sum of the length L42 of the second zone 42.2 of the body 42 and the thickness E of the washer 43, measured along the length X40 axis, is strictly less than the length L44 of the insert 44, measured along the axis X. Thus, in the assembled configuration of the freewheel body 40, an end portion 44.1 of the insert 44 protrudes beyond the body 42, along the axis X. The thickness of the end portion 44.1 is relatively small but its mechanical strength is satisfactory because the material used to make the insert 44 is resistant, as explained below. An externally threaded washer 48 is provided to engage the tapping of the end portion 44.1. This washer has an outer flange 48.1 which axially retains a pinion cassette 46 against the shoulder 42.3. Thus the portion 44.1 of the tapping which is not in contact with the threaded surface of the second zone 42.2 is used for the assembly of the washer 48 and thus for the axial retention of the pinions 47. The outer surface S44B of the insert 44 is provided with external ribs or splines 44.2 parallel to the axis X40 which form reliefs for rotationally fastening the freewheel body 40 with the pinion cassette 46, which is provided with complementary securing reliefs. In the example shown, the pinion cassette 46 is composed of several individual pinions 47 of different diameters, separated from each other by spacers 48 mounted around the insert 44. In a variant, the pinion cassette 46 is of a single taking. Adhesive means not visible in the figures, such as two-component epoxy adhesive or anaerobic monocomponent, are placed at the thread between the body 42 and the insert 44, namely on the inner surface S44A of the insert 44 and / or on the outer surface S42.2 of the body 42.

The threading considerably increases the bonding surface existing between the insert 44 and the body 42. This surface is almost doubled, which increases the level of resistance of the bonding. On the other hand, the bonding of the threaded connection between the insert 44 and the body 42 has the effect, on the one hand, to prevent the expansion of the insert and, on the other hand, to avoid contraction. of the body 42 and the tightening of the bearing. It has been established that it is possible to transmit a torque of 300 Nm by the bonded / screwed connection of the invention without any deterioration of the operation of the hub. During assembly of the freewheel body 40, the washer 43 is installed around the threaded portion 42.2 of the body 42, against the shoulder 42.3. The adhesive means are arranged. Then, the insert 44 is screwed onto the body 42 until it abuts against the washer 43. Preferably, during assembly of the freewheel body 40, the threading is prestressed with the aid of a tightening torque of about 30 Nm.

The threading and the complementary tapping of the body 42 and of the insert 44 constitute means for assembling the body 42 with the insert 44. After the adhesive means are put in place, the body 42 and the insert 44 are fixed rigidly. to one another. In use, the cycle chain drives the cassette of sprockets 46 in rotation. This driving torque is transmitted to the freewheel body 40 by means of the grooves 44.2 which are subjected to high pressures. The materials from which the body 42 and the insert 44 are made are different. For example, the body 42 is made of aluminum alloy, which contributes to limiting the weight of the freewheel body 40, and the insert 44 is made of steel, so as to ensure good mechanical resistance to the pressures transmitted by the gear cassette 46. The washer 43 can be made for example from an aluminum alloy. Thus, the overall weight of the free wheel body 40 is reduced because the body 42 is relatively light. The freewheel body 40 has good mechanical strength because the insert 44 is made of steel. The direction of the thread between the body 42 and the insert 44 is chosen so that when the cyclist pedal in the direction of advance of the cycle, the insert 44 tends to screw on the body 42. The use of adhesive means allows to prevent the onset of radial stresses that are formed when the insert 44 is screwed with the body 42, especially during the use of the cycle. When a screw-nut connection such as that formed by the body 42 and the insert 44 is tightened, this generates radial stresses which tend to reduce the diameter of the screw, that is to say the diameter of the body 42, and to increase the diameter of the nut, that is to say the diameter of the insert 44. The use of adhesive means makes it possible, during the tightening of the screw-nut connection, not to solicit the threading to transmit the torque motor, because it is the adhesive means that transmit the torque without the threading is solicited. The insert 44 may be manufactured by machining, that is to say machined by removal of material from a metal bar. It is not necessary to manufacture the insert 44 from a forge, the cost of the insert 44 is reduced. The geometry of the insert 44 can be modified according to the standards of the gable cassette manufacturers, keeping the same body 42. In this way, the invention makes it possible to propose a range of products adapted to different standards, while maintaining the same body 42. In a variant, the ring 43 is removed and the insert 44 bears directly against the shoulder 42.3. In the context of the invention, the different variants can be combined with each other.

Claims (10)

CLAIMS1.- Freewheel body (40) of a freewheel hub (2), this freewheel body (40) comprising: - a body (42) comprising assembly means (41), with possibility of unidirectional rotation, with a hub body (20) of the freewheel hub (2), - an insert (44) mounted around the body (42) and made from a material different from that of the body (42) ), the insert (44) having means (44.2) for securing in rotation with a pinion cassette (46), characterized in that the body (42) and the insert (44) are assembled together at a time by complementary assembly means (S42.2, S44A) and by adhesive means. 2.- Freewheel body (40) according to claim 1, characterized in that the complementary assembly means (S42.2, S44A) are constituted by a thread of the body (42) and by a tapping complementary to the insert (44). 3. Freewheel body (40) according to claim 2, characterized in that a threaded portion (44.1) of the insert (44) protrudes beyond the body (42) along an axis. central (X40) of the freewheel body (40). 4.- Freewheel body (40) according to one of the preceding claims, characterized in that the body (42) is made from an aluminum alloy. 5.- Freewheel body (40) according to one of the preceding claims, characterized in that the insert (44) is made from a steel alloy. 6. Freewheel body (40) according to one of the preceding claims, characterized in that the insert (44) is manufactured by bar turning. 7.- Freewheel body (40) according to one of the preceding claims, characterized in that the adhesive means are constituted by glue, including two-component epoxy adhesive or monocomponent anaerobic. 8.- Freewheel body (40) according to one of the preceding claims, characterized in that the insert (44) bears against a shoulder (42.3) of the body (42), optionally via a washer (43). 9.- free wheel hub (2), comprising a central shaft (10) defining an axis of rotation (X), a hub body (20) and a freewheel body (40) rotatably mounted around the central shaft (10), characterized in that the freewheel body (40) is according to one of the preceding claims. 10.- cycle wheel, characterized in that it comprises a freewheel hub (2) according to claim 9.