WO2010016022A1

WO2010016022A1 - Tightening device with cam lever

Info

Publication number: WO2010016022A1
Application number: PCT/IB2009/053423
Authority: WO
Inventors: Alberto Bertani
Original assignee: Elesa S.P.A.
Priority date: 2008-08-07
Filing date: 2009-08-06
Publication date: 2010-02-11
Also published as: DE112009001858T5; DE112009001858B4; IT1391103B1; DE112009001858B8; ITMI20081494A1

Abstract

The invention concerns a device for the tightening of two elements (1, 2) one against the other, comprising a tie-rod (3) and a tightening lever (7) rotating about a pin (6). The tie-rod (3) is steadily anchored to a first element (1) and runs freely through the other element (2) anchoring itself on said pin (6). The end of lever (7) articulated on pin (6) is fork-shaped, the two arms whereof have a profile shaped as an excentric cam with respect to the axis of pin (6), such profile bearing on an adjustable spacer, which in turn is run across by said tie-rod and bears on said second element (2). According to the invention, said spacer consists of two bushes (11, 12), a lower one (11) and an upper one (12), resting one against the other and ro- tatable and axially slidable one with respect to the other; the mutually bearing surfaces (11c, 12c; 11d, 12d) of said bushes (11, 12) consist of two annular, spiral-shaped surfaces, each of which develops across an arc not greater than 180°, with slopes ascending in the same circumferential direction, and which are separated by radial, diametrically opposite step walls. With one of these annular surfaces there is associated a circular groove (11b), and with the other there is associated an axial appendix (19), which engages with said circular groove.

Description

"TIGHTENING DEVICE WITH CAM LEVER'

The object of the present invention is a tightening device with a cam lever. Devices of this kind are largely known and are generally employed for accomplishing the tightening of two mechanical elements one against the other. A particular use is, for example, that of tightening the two arms of a clamp, one agagainst the other, or the tightening of the hubs of bicycle wheels on the brackets of the frame fork, or the like.

A known device of this kind is shown for example in EP- 1,726,403, of which a diagrammatic axial section is shown as fig. 1 in the annex, for a correct understanding of the known art and of the present invention.

As shown there, the tightening device is provided for tightening two elements 1, 2 one against the other. For this purpose, the two elements are run across, with minimal play, by a tie-rod 3, which can be in the shape of a bolt. This bolt carries at one end a retaining nut 4 and at the other end a support 5 for a pin 6 for the articulation of a tightening lever 7. At the end closest to pin 6, lever 7 widens out into an essentially cam-shaped body 7a, having for example a spiral-shaped profile 7a¹, or even simply a circular profile out of centre with respect to the axis of pin 6.

In the tightening position, shown by solid lines in fig. 1, cam body 7a abuts on element 2 with the placing of a spacer 8, 9 in between, better described in the following; as appears from fig. 1, this abutting relationship occurs with the part of profile 7a¹ at the maximum distance from the axis of pin 6. In this position nut 4 is closely applied against element 1, to accomplish the desired tightening of the two elements 1, 2 one against the other.

For unblocking, lever 7 is rotated by about 180° into the position shown by 7' with discontinued lines, wherein cam-shaped body 7a has the portion of profile 7a' thereof being closest to the axis of pin 6 opposed to element 2, i.e. to spacer 8, 9. As a result, an axial play originates, corresponding to the difference between said maximum distance and said minimum distance of profile 7a' from the axis of pin 6; this axial play implies a loosening of the tightening, such that the two elements 1 and 2 can be spaced apart from each other.

Again according to the known art of EP-I, 726, 403, the bearing spacer consists of two bushes 8, 9, screwed one on the other. Through a greater or smaller screwing of such two bushes it is obtained to adjust the tightening of the device; such an adjustment is essential both during the mounting of the device, and when it is necessary to accomplish a taking up of the slacks determined by the wear of the device during use. The adjustment is carried out, very simply, by gripping with a hand lever 7 to alternately bring it from the tightening position to the unblocking position, while with the other hand one of the bushes 8, 9 is caused to rotate with respect to the other, until the desired position is found wherein lever 7, arranged in correspondence of the blocking position thereof shown in fig. 1, accomplishes the maximum admissible tightening.

However, although this solution is effective, it has the drawback that the adjustment of the screwing of the two bushes is not so immediate and simple when the screwing pitch is of the standard type, i.e. it implies a relatively small axial shift (i.e. 1.25 mm) with respect to a relatively wide rotation (i.e. a full rotation, of 360°) of one of the two bushes 8, 9 with respect to the other; in actual fact, the operator must always perform a very wide rotation of the bushes in order to obtain a relatively modest axial adjustment.

The object of the invention is therefore to propose a device of the general type described in publication EP-I, 726, 403, which allows a very easy and quick adjustment, but at the same time highly stable arrangement during use, which gives the operator an immediate perception of the adjustment position, and which allows reduction of component wear. This result is obtained by the features mentioned in claim 1. Further features and advantages of the invention, however, are more evident from the following detailed description of a preferred embodiment, given purely by way of a non-limiting example and shown in the accompanying drawings, wherein: fig. 1 has already been described and concerns a device of the known art; fig. 2 is an overall view of the tightening device according to the present invention, in a vertical section running through the axis of the tightening tie-rod; fig. 3 is a perspective, exploded view of the different parts making up the device according to the invention, except for the tightening tie-rod; figs. 4a, 4b, 4c and 4d are views of the lower bush of the device according to the invention, respectively in perspective, top plant, from one side and from another side at 90° to the previous one; and figs. 5a, 5b, 5c, 5d and 5e are views of the upper bush of the device according to the invention, respectively perspective from below, bottom plant, top, on one side and on another side, at 90° to the previous one, views.

As it is evident from figures 2 to 5, the tightening device according to the invention comprises, in a known manner, a tie- rod 3 steadily fastened by one end thereof to a fixed element 1, of the two elements to be tightened, and runs freely across second element 2, to engage with the other end thereof with the tightening device according to the invention.

This tightening device essentially comprises a control lever 7, with an articulation pin 6 thereof, an adjustment bush 11 and a bearing bush 12, as well as a connection sleeve 13. All these elements are described in detail in the following.

Control lever 7 has a free gripping end and the opposite end widening out into a fork-shaped body (see better in fig. 3} . The two arms 14 and 15 of the fork are mirror-like symmetrical and each has a circular, horizontal cut-out 16 (here and in the following the terms "horizontal" and "vertical" refer only to the views of the drawings, since it is clear that the device accord- ing to the invention can take on any position, different from horizontal or vertical), for the housing of pin 6.

This pin 6, as figs. 2 and 3 equally show, is provided with perforation 6a, perpendicular to the axis thereof, intended for tie-rod 3 to run through, and possibly for supporting a widened head thereof (not shown) on the flared-out edge of the same perforation 6a.

For the purpose of a secure and stable retaining of pin 6 on arms 14, 15 of lever 7, there are further provided

- a levelled surface 6b, parallel to the axis of the same pin 6, acting as keying against rotation; this surface cooperates with a corresponding, levelled surface 13c inside part 13b of sleeve 13 (better described in the following) ;

- a pair of circumferential grooves 6c, formed in the proximity of the ends thereof, acting as keying against sliding in the direction of the axis of the same pin 6; these grooves couple with a pair of annular ribs 14b, 15b formed on arms 14, 15, inside respective cut-outs 16.

In an embodiment, shown in fig. 6, the retaining in the direction of the rotation axis is secured, in addition to annular ribs 14b and 15b, also by a small relief or short, straight rib 13f, protruding transversally to the planar face 13c of sleeve

13 which is apt to engage with a corresponding groove (not shown) in the planar face 6b of pin 6; this rib 13f is used for perfectly engaging with pin 6, even when it may be at the limit of its negative tolerance, and it is a guarantee that, also with an unmounted device, pin 6 cannot come out laterally from arms

14 or 15 of lever 7.

Sleeve 13 consists of a main part 13a, of a cylindrical shape having a vertical axis, and of a joining part 13b, of an equally cylindrical shape, but having a horizontal axis.

This cylindrical joining part 13b is open at the two ends thereof and two circular cut-outs are further formed therein, an upper one 17a and a lower one 17b, which lie on the extension of the vertical-axis cavity of main part 13a and also on the extension of perforation 6a of pin 6. Moreover, the inner surface of cylinder 13b has a levelled area 13c, acting as keying upon rotation, already described above.

Finally, on the outer wall of part 13a two diametrically opposite teeth 18 are formed, while the lower contour thereof is limited by a lip-shaped edge 13d; this edge is preferably elas- tically yielding, for the function better described in the following.

Upper bush 12 has a widened-out central perforation, which determines an annular upper surface; this one has two diametrically opposite, planar parts 12a, separated by two concave parts 12b. These last ones are sectors of cylindrical surfaces having a horizontal axis (see better in fig. 5d) .

According to the fundamental feature of the present invention, and as better visible in figures 5, the lower annular surface of bush 12 is divided into two sectors 12c and 12d (see figs. 5a and 5b), each of which develops across 180° and is sloped; more precisely, the two surfaces 12c, 12d are joined by two steps 12e, from the top of which they have slopes sloping down into opposite directions F, F' . In the proximity of one of teeth 12e an end-of-travel appendix 19 is further formed, protruding downwards .

The inner wall of the central perforation of bush 12 is furthermore provided with two axial grooves 12f, the width and depth whereof substantially correspond to the width and thickness of teeth 18 of sleeve 13.

Lower bush 11 has a cylindrical inner cavity 11a, the diameter of which is just above the diameter of the outer cylindrical surface of upper bush 12, so that said upper bush can be housed in the cavity 11a of the first one.

Equally according to the fundamental feature of the present invention, and as better visible in figures 4, on the bottom of cavity 11a there is formed an annular surface divided into two sectors lie and Hd (see figs. 4a and 4b), each of which develops across 180° and is sloping; more precisely, these surfaces Hc and Hd are joined by two steps He, from the top of which they slope down to opposite directions F, F¹, hence with a sub- stantially identical shape and mirror-like symmetrical to surfaces 12c and 12d of bush 12. Thereby, these last ones rest perfectly on the first ones when bush 12 is housed in bush 11.

In surface Hd a circular groove Hb is further obtained, of a size apt to house end-of-travel appendix 19, as better described in the following.

In the inner wall of the central perforation of bush 11 an annular rib Hf is further formed, ever so slightly in relief and preferably elastically yielding for the function better described in the following.

Finally, as shown by fig. Ae₁ the lower surface of bush 11 is provided with a series of small rotation-preventing teeth Hh, Hi and Hj; more precisely, these are teeth Hh in the shape of circular rib sectors, and teeth Hi and Hj shaped as opposite arrows and positioned along two circumferential bands, a fist one for teeth Hi, and a second one for teeth Hj, respectively, outwardly and inwardly to the series of circular ribs Hh. These teeth are used for guaranteeing a perfect adherence of the device according to the invention to the surface of the element 2 to be tightened, giving greater stability with respect to involuntary, lateral movements. At the same time they impart stability to the device during the adjustment operation.

As fig. 2 shows clearly, the different elements 6, 7, H,

12, 13, making up the device according to the invention, are mounted in the following way:

- sleeve 13 is firstly introduced between arms 14 and 15 of lever 7, so that its connecting part 13b arranges itself with the axis thereof coinciding with the axis of cut-out 16. Pin 6 is then introduced through cut-outs 16 and part 13b of sleeve

13. In order to obtain a correct introduction, levelled surface 6b of pin 6 must arrange itself in correspondence of the levelled part 13c of the sleeve; thereby, a coupling is accomplished which makes pin 6 perfectly integral with part 13b of sleeve 13 to rotation;

- this keying-on to rotation is integrated by a keying on to axial sliding, which - as detailed above - is guaranteed, on one side, by the coupling between the pair of circumferential grooves 6c of pin 6 and the pair of annular ribs 14b, 15b, formed on arms 14, 15 and, on the other side, by the coupling between straight rib 13f, projecting transversally to the planar face 13c of sleeve 13 and the corresponding groove (not shown) in the planar face 6b of pin 6;

- subsequently, bush 12 is introduced from below, on the main part 13a of sleeve 13. Introduction is easy, since the inner diameter of the central perforation of bush 12 is remarkably larger than the outer diameter of the cylindrical part 13b of the sleeve; during this operation, however, teeth 18 projecting from the outer surface of the sleeve 13 must engage with the axial grooves 12f of bush 12;

- the engagement of teeth 18 with grooves 12f causes upper bush 12 to be able to slide axially with respect to sleeve 13, but is integral with the same during rotation. Once this engagement has been accomplished, bush 12 is caused to slide upwards, so as to bring the concave surfaces 12b thereof in contact with the lower surfaces of arms 14, 15 of lever 7;

- subsequently, bush 11 is also introduced in the main part 13b of sleeve 13; also the central perforation of bush 11 has a remarkably larger diameter than the outer diameter of part 3b of the sleeve, which makes introduction easy. It is only necessary, during the final introduction phase, to impart a pressure sufficient for lip edge 13d to surmount annular rib Hf, through a slight elastic yielding of both. Due to this, bush 11 remains anchored to sleeve 13 and retains in position also bush 12.

Once the tightening device according to the present invention has been thus assembled, it is possible to supply it directly to the user - in a so-called "bush version" configuration - or it is first provided to complete it, introducing tie-rod 3 into the coaxial cavities of pin 6 (shown as 6a) and of sleeve 13; the upper end 3a of tie-rod 3 will rest on the edge of perforation 6a, while the lower end 3b thereof will be provided with a temporary blocking element, such as a nut 4 or the like.

The operation of the tightening device according to the in- vention is evident from the description of the known art, given in the premise with reference to figure 1. As concerns specifically the adjustment of the tightening pressure through bushes

11 and 12, it must simply be noticed that, on the one hand, bush

12 is fixed during rotation, since it is retained by the engagement of axial grooves 12f thereof with teeth 18 of sleeve 13, it rests with the spiral surface 12c thereof on the opposite spiral surface lie of bush 11, and it engages appendix 19 thereof with groove lib of bush 11; on the other hand, bush 11 is rotatable and the rotation thereof with respect to bush 12 is limited to an arc of about 180°, due to said engagement of appendix 19 with groove lib.

Due to this construction, when one wants to change the overall height of the spacer, it is firstly provided to bring lever 7 in unblocking position 7' . Thereby, a play originates between the outer surface of arms 14, 15 and the upper surface 12b of bush 12, such as to allow a loosening of the tightening of the device, sufficient to allow a manual intervention for rotating bush 12, with a sliding of oblique surfaces lie, 12c one on the other; there results a moving apart (greater tightening of the device) or coming closer (smaller tightening) of the two bushes, according to the direction of rotation of bush 11.

The outer lateral surface of bush 11 is corrugated (zigzag made or otherwise corrugated to improve gripping) , except on a smooth area Hg (or in any case treated superficially so as to differentiate itself from the remaining corrugated surface) , the upper edge of which has a raising contour, which is substantially parallel to the slope of the spiral surface Hc inside bush 11; this surface Hg supplies the operator with an indication of the direction in which bush 11 must be rotated to obtain a moving away or coming closer, respectively, of the two bushes, i.e. an ascent or descent, respectively, of bush 12.

As can be easily understood, the tightening device according to the present invention has various advantages:

- firstly, it is designed to avoid causing possible problems even when it is not mounted in an operating position yet, as de- tailed in the following, in particular to prevent the user from incorrect mounting. Lever 7 is in fact retained against accidental rotation about the vertical axis of tie-rod 3, with respect to bush 12, not only due to the engagement of teeth 18 of sleeve 13 with grooves 12f thereof, but also due to the arms 14, 15 of lever 7 bearing in the two concavities 12b of the upper surface thereof; as a matter of fact, these two concavities 12f prevent the rotation of lever 7 about the vertical axis due to the geometric engagement with the surfaces of said arms 14, 15. Teeth 18, which improve this anti-rotation effect, have in actual fact a fundamental function when the device is not yet fastened to a plane by tie-rod 3, but is simply assembled in the parts thereof - in a temporary package, as shown in fig. 2 - to be supplied to the user; in this arrangement, pin 6 is introduced and blocked in cut-outs 16 of lever 7 and in part 13b of sleeve 13, but bushes 11 and 12 are only retained by the undercut formed by lip edge 13d and by annular rib Hf. In these conditions there exists a freedom of axial movement of the bushes, which instead is not present when the device is fastened to a plane by a central tie-rod: lever 7 could therefore be lifted from the seats 12b of bush 12 and pushed upwards as far as the play between undercut ribs 13d and Hf allows. Such play is greatest when the lever is in a relaxed position (position 7' of fig. 1) and the inclined surfaces of sectors 12c, 12d, Hc, Hd are in the minimum position. In such conditions, lever 7 may come out of seats 12b and, if used incorrectly, it may rotate about the vertical axis and then damage bush 12. In order to avoid that, teeth 18 are provided, constraining in all possible conditions lever 7 to bush 12. The length of teeth 18, according to the vertical axis, is limited with respect to the length of sleeve 13: this is to prevent such teeth 18 from interfering with rib Hf found on bush

11 in certain operating conditions. Likewise, tooth 19 of bush

12 is of such a length to prevent, in the above-cited case of maximum play between the pieces, with the device still unmounted, bush 12 from rotating about bush 11 beyond the angle defined by the circular development of groove Hb. - moreover, it allows, as already said, a very easy and quick adjustment, due to the fact that a screwing action across multiple rotations of lower bush 11 on upper bush 12 is no longer necessary, but the entire mutual axial run of the two bushes is obtained with a rotation of 180° at most of sole lower bush 11;

- at the same time, the adjustment is very stable, because the only rotating piece is bush 11, which can be made of a suitable plastic material, i.e. the sliding surfaces thereof - i.e. both the inclined upper surfaces lie, Hd, and the lower surface provided with teeth Hh, Hi, Hj - can have a ruggedness to such an extent as to avoid an accidental backward rotation and hence a loss of adjustment;

- moreover, the shaped surface Hg of bush 11 supplies each operator with an immediate perception of the adjustment position, which is evidently advantageous, both during the adjustment itself and during use, to provide an indication of the tightening force of the device;

- finally, component wear occurs only in correspondence of the bearing area of arms 14, 15 of lever 7 on saddles 12 of bush 12, i.e. in correspondence of surfaces which, due to the nature of the material they are made of and/or due to their shape, are durable in time.

However, it is understood that the invention must not be considered limited to the particular arrangement illustrated a- bove, which represents only a preferred embodiment, but various changes are possible, all within the reach of a person skilled in the field and therefore falling within the scope of protection of the invention, as defined by the following claims.

Claims

1) Device for tightening two members (1, 2) one against the other, of the type comprising a tie rod (3) and a tightening lever (7) rotatable about a pin (6), the tie rod (3) being steadily anchored to a first one (1) of said members and freely running through the other member (2), anchoring to said pin (6), the end of said lever (7) articulated on said pin (6) being cam- shaped, with a profile eccentric with respect to the axis of the pin (6), the profile of said cam bearing on an adjustable spacer, which is in turn run through by said tie rod and bears on said second member (2) ,

- characterised in that said spacer consists of two bushes (11, 12) , a lower bush (11) and an upper bush (12) , resting one against the other and rotatable and axially slidable one with respect to the other,

- and in that the mutually bearing surfaces (lie, 12c; Lid, 12d) of said bushes (11, 12) consist of two spiral-shaped, annular surfaces, each of which develops over an arc not exceeding 180°, said surfaces having upward slopes in the same circumferential direction, and being separated by diametrically opposite, radial step walls.

2) Tightening device as claimed in claim 1) , characterised in that a circular groove (lib) is associated with one of said mutually bearing, annular surfaces, said groove developing over the peripheral contour, over an arc smaller than 180°, and in that, with the other one of said surfaces, an axial appendix (19) is associated, which appendix engages with said circular groove.

3) Tightening device as claimed in claim 1) , characterised in that said manoeuvring lever (7) ends fork-shaped, the two arms (14, 15) whereof have each an identically-shaped profile, forming said cam-shaped part.

4) Tightening device as claimed in any one of the preceding claims, characterised in that with said tightening lever (7) there is associated a sleeve (13) for guiding said upper bush (12) and lower bush (11), guiding means (12f, 18) for the axial sliding and retaining means against mutual rotation being associated respectively with the outer surface of said sleeve and with the inner surface of said upper bush.

5) Tightening device as claimed in claim 4) , characterised in that said guiding means consist of at least one tooth (18) fastened to the outer surface of said sleeve and of at least one axial groove (12f) , formed on the inner surface of said upper bush (12) .

6) Tightening device as claimed in any one of the preceding claims, characterised in that said sleeve consists of a vertical-axis, cylindrical-shaped main part (13a), and of a horizontal-axis, cylindrical-shaped connection part (13b) , intended to form the housing for said pin (6) of the manoeuvring lever (7) .

7) Tightening device as claimed in claim 6), characterised in that said cylinder-shaped connection part (13b) , is open at the two ends and therein there are further formed two circular cut-outs (17a and 17b) , which are aligned with the vertical-axis cavity of the main part (13a) , this main part (13a) and said circular cut-outs (17a and 17b) forming a housing for said tie rod (3) .

8) Tightening device as claimed in claim 6) , characterised in that the inner surface of said cylinder-shaped part (13b) has a levelled area (13c) , cooperating with a corresponding levelled surface (6b) of the pin (6) to accomplish a function of keying on upon rotation.

9) Tightening device as claimed in claim 6) or 8), characterised in that said two levelled surfaces (13c, 6b) are provided with a rib (13f) and with a groove, respectively, capable of cooperating one with the other to accomplish a function of keying on against the axial sliding of said pin (6) .

10) Tightening device as claimed in claim 6) , characterised in that said pin (6) has a pair of circumferential grooves (6c), formed in the proximity of the ends thereof, keying on against sliding in the direction of the axis of the same pin (6) , cooperating with a pair of annular ribs (14b, 15b) , formed on the arms (14, 15), inside respective cut-outs (16) for housing the pin (6) .

11) Tightening device as claimed in any one of the preceding claims, characterised in that said upper bush (12) has an annular upper surface (12a, 12b) which surrounds the widened central perforation thereof, and which is divided into two diametrically-opposite, plane sectors (12a) , separated by two concave sectors (12b) .

12) Tightening device as claimed in claim 11) , characterised in that said concave sectors (12b) have cylindrical surfaces, having a common horizontal axis, and act as a bearing for said two cam-shaped end arms (14, 15), of said manoeuvring lever (7) .

13) Tightening device as claimed in any one of the preceding claims, characterised in that said lower bush (11) has, in the inner wall of the central perforation thereof, an annular rib (llf), and said main part (13a) of said sleeve (13) has at the lower end thereof a lip edge (13d), said rib and said lip edge being just in relief and preferably elastically yielding, so as to form a yielding undercut.

14) Tightening device as claimed in any one of the preceding claims, characterised in that said lower bush (11) has, on the lower surface thereof, a series of teeth (Hh, Hi and Hj), shaped as sectors (Hh) of a circular rib and as reliefs (Hi, Hj) shaped as opposite arrows, arranged on concentrical, circumferential bands, so as to accomplish an anti-rotation adherence function of the lower bush (11) on the surface of element (2) to be tightened and/or, said lower bush having also, on the lateral surface thereof, marks (Hg) indicating the slope direction of the inner bearing surface (Hc, Hd) .