GB2073339A

GB2073339A - Free-wheel coupling

Info

Publication number: GB2073339A
Application number: GB8109710A
Authority: GB
Original assignee: Nadella SA
Current assignee: Timken France SAS
Priority date: 1980-03-31
Filing date: 1981-03-27
Publication date: 1981-10-14
Also published as: GB2073339B; IT8148140A0; FR2479380B1; IT1142378B; FR2479380A1

Abstract

In a free-wheel coupling, wedging needles (5) are retained in cavities (3) formed in a single cylindrical sheet-metal cage (1). When the needles (5) are out of engagement with the ramps (13), the cage (1) bears radially against the cylindrical raceway (31) through flanges (29) on the cage. The cage also has radial projections (27) which are in sliding contact with the smooth cylindrical raceway (7) or with both raceways. <IMAGE>

Description

SPECIFICATION Free-wheel coupling device The present invention relates to a free-wheel coupling device comprising a plurality of wedging elements of cylindrical shape interposed between two concentric cylindrical raceways, one of which raceways is smooth whereas the other is provided with wedging ramps in the region of which ramps the respective wedging elements are circumferentially and axially retained in cavities, means being provided for constituting between the two cylindrical raceways a sliding bearing forthe smooth cylindrical raceway when the cylindrical elements are out of engagement with the wedging ramps.

Such an arrangement, which enables a radial load to be supported, when the device operates as a free-wheel, with no need to associate with the device a distinct rolling bearing or smooth bearing, is known from French Patent 2,340,476 (STIEBER DIVI SION) in which each cavity is defined by an individual cage which is fixed to the cylindrical raceway provided with the ramps and has surfaces which form a sliding support for the smooth cylindrical raceway.

An object of the present invention is to simplify and cheapen the known device. According to the invention, there is provided a free-wheel coupling device of the aforementioned type, wherein the cavities receiving the wedging elements are formed in a single cylindrical cage of thin sheet metal which radially bears against the cylindrical raceway provided with ramps and which comprises at least three radial projections in sliding contact with the smooth cylindrical raceway, said projections being formed by a forming operation on the sheet metal of the cage.

Owing to the face that the cylindrical cage is centered both on the smooth cylindrical raceway and on the cylindrical raceway provided with the ramps, the device operates as a smooth bearing when the wedging elements are in the inoperative position thereof and one of the parts carrying the respective cylindrical raceways, constituted for example by a shaft and a ring, rotates with respect to the other part.

The radial bearing of the cage on the cylindrical raceway provided with ramps may be achieved by means of two radial flanges formed at the respective ends of the cage. It is also possible to provide, instead of the radial flanges, radial projections extending in the opposite direction to those which have a sliding contact with the smooth cylindrical raceway.

Further features and advantages of the invention will be apparent from the ensuing description which is given solely by way of example with reference to the accompanying drawing in which: Figure 1 is a cross-sectional view of a coupling device according to the invention; Figure 2 is a perspective view of a portion of the cage of the coupling of Fig. 1; Figure 3 is a sectional view taken on line 3-3 of Fig. 1, and Figure 4 is a perspective view of a part of a modification of the cage of Fig. 2.

The free-wheel coupling device shown in Fig. 1 in the drive-transmitting state thereof, comprises a cage 1 having cavities 3 for maintaining and/or guiding a plurality of wedging elements 5 formed by rollers or needles and disposed between a smooth cylindrical inner raceway 7 carried by for example a shaft 9, and an outer cylindrical raceway 11 having a circular series of wedging ramps 1 3 carried by a ring 1 5 for example, the biasing of the wedging elements into the locking position thereof being ensured by an outer radial tab 1 7 which is attached to, or cut out from, the cage and at the end of which bears a spring 1 9 which has an opposite end bearing against the radial wall 21 of an axial groove 23 in the ring 1 5. It must be understood that other biasing means for the wedging elements may be employed.

Fig. 2 shows the cage 1 according to the invention obtained by a blanking and forming operation, without the removal of cuttings, of a section of a tube or of a planar metal sheet which is rolled and welded, so as to form therein rectangular cavities 3 the longitudinal sides 24 of which have substantially radial tabs 25 which extend in opposite directions and are adapted to retain and guide the corresponding wedging elements.The cylindrical wall 26 of the cage is subjected locally and within the limits of its effective width, to a cold forming operation including a blanking in accordance with the illustrated embodiment so as to form at at least three places spaced 1 20' apart, each of which is located between two consecutive cavities 3, a radial projection which internally extends the wall 26 in the form of a cup portion 27 which has oblique lateral walls 28 connected to a bottom wall 30 which forms a shoe whose dimensions are close to those of the cavities of the cage.

Formed at the end of the cage are outwardly extending radial flanges 29. Said shoes, which are for example three in number and equally spaced apart on the periphery of the cage, constitute bearing surfaces for centering and sliding on the smooth cylindrical raceway 7. The cage bears on, and is centered by, the outer ring, and more precisely on the portions 31 thereof located between two consecutivn ramps 13, through the flanges 29 of the cage which consequently performs the function of a smooth bearing supporting the radial load when the coupling operates as a free-wheel.

This double centering and this bearing function are more particularly shown in Fig. 3.

It is clear from the foregoing description that the invention permits the use of the conventional method for manufacturing a rolling bearing cage by blanking and forming a strip or a section of a tube which is relatively thin to provide a cheap cage for a free-wheel which also forms a bearing with no need to extend it axially beyond the flanges.

If the diameter of the wedging elements so permits, it is possible, as shown in Fig. 4, to inwardly deform the cylindrical wall 26 of the cage 1 so as to obtain in at least three places spaced 120 apart and, of course, cicumfer entiaily offset with respect to the cup portions 27, the bottom wall 30 of which forms a sliding shoe, a radial projection defining a cup portion 27 the bottom wall 33 of which bears against a portion 31 of the cylindrical raceway 11. Preferably, and as shown in Fig. 4, each bearing cup portion 27 which extends radially outwardly is adjacent to a sliding cup portion 27 which extends radially inwardly.This arrangement ensures, when the device operates as a free-wheel, the double centering of the cage by pairs of cup portions, for example three pairs, equally spaced apart, on one hand on the portions 31 of the outer ring and, on the other hand, on the inner smooth cylindrical raceway 7, with no need to form radial flanges.

It must be understood that the scope of the invention is in no way intended to be limited to the described and illustrated embodiments.

Thus, the bearing and sliding portions, obtained by forming and/or cutting out the wall 26, may have different shapes, orientations or arrangements.

Further, the arrangement shown in Fig. 1 may be reversed by forming a cage provided with outer projections 33 centered between the ramps and the inner end flanges 29 centered on the inner raceway 7.

It may be envisaged to apply the foregoing modifications to a free-wheel whose smooth cylindrical raceway is carried by the outer ring and whose ramps are formed on or attached to the inner ring.

Claims

1. A free-wheel coupling device comprising a plurality of wedging elements of cylindrical shape interposed between two concentric cylindrical raceways, one of which raceways is smooth whereas the other is provided with wedging ramps in the region of which ramps the respective wedging elements are circumferentially and axially retained in cavities, means being provided for constituting between the two cylindrical raceways a sliding bearing for the smooth cylindrical raceway when the cylindrical elements are out of engagement with the wedging ramps, wherein the cavities receiving the wedging elements are formed in a single cylindrical cage of thin sheet metal which radially bears against the cylindrical raceway provided with ramps and which comprises at least three radial projections in sliding contact with the smooth cylindrical raceway, said projections being formed by a forming operation on the sheet metal of the cage.

2. A device according to claim 1, wherein the radial projections define cup portions having bottom walls in sliding contact with the smooth cylindrical raceway.

3. A device according to claim 2, wherein the bottom wall of the cup portions constitutes a sliding shoe and has dimensions close to the dimensions of a cavity.

4. A device according to claim 1, 2 or 3, wherein the cage bears radially against the cylindrical raceway provided with the ramps through two radial flanges formed at respective ends of the cage.

5. A device according to claim 1, 2 or 3, wherein the cage bears radially against the cylindrical raceway provided with the ramps through radial projections which extend in the opposite direction to said projections having a sliding contact with the smooth cylindrical raceway.

6. A device according to claim 5, wherein the radial bearing projections define cup portions having a bottom wall which bears against the cylindrical raceway provided with ramps.

7. A device according to claim 5 or 6, wherein each bearing projection is adjacent to a sliding projection so as to form in the cage at least three pairs of projections, the projections of each of said pairs extending radially in opposite directions.

8. A free-wheel coupling device, substantially as hereinbefore described with reference to and as shown in Figs. 1 to 3 or Fig. 4 of the accompanying drawing.