ITMI980062A1 - AXIAL POSITIONING DEVICE OF THE BRAKE BAND FOR DISC BRAKES - Google Patents

Description

Description of a patent application for an industrial invention entitled: "Device for axial positioning of the braking band, for disc brakes".

DESCRIPTION

The invention relates to a device for axial positioning of the braking band, for disc brakes for motorcycles, in which the screws with connecting bushes between the aforementioned braking discs and the wheel hubs are combined with springs with a shaped profile which include folded side arms for centering and an orthogonal tooth for transversal positioning. The springs, engaged to the screws with connecting bushes, enter into engagement relationship in adherence with the lateral walls of radial slots; they allow adequate and necessary radial sliding of brake discs subject to thermal expansion; they allow a constant adherence between the connection bushings and the walls of the same slots at the contact and dragging points; and allow a constant axial self-centering of said discs with respect to the braking pads which operate simultaneously on their opposite parallel faces.

This condition guarantees over time a constant centered maintenance of the parallel braking bands of the discs, in relation to the positions that the braking pads take up, activated by the hydraulic pistons sliding in the seats of the relative calipers. The aforementioned centering avoids the onset of irregular wear of the parts and low-frequency vibratory phenomena, known with the name of "judder".

It is known that in current construction techniques, the brake discs for small to medium power motorcycles, which are cheaper and with lower performance, are simply made in a single block with the bell or hub engaged in the center of the wheels. It is evident that the coupling of said discs with the control calipers and with the brake pads themselves is geometrically rigid and without the possibility of adaptation and / or self-alignment of the parts, with consequent non-uniform wear phenomena of the associated components. The aforementioned conditions, although reasonably acceptable from the point of view of industrial economy, and in any case not prejudicial from the point of view of safety in relation to the limited performance of these motorcycles, certainly cannot be adopted for higher performance machines.

For this reason, so-called floating discs are currently being adapted to large displacement motorcycles with high power and speed, in which the braking band, i.e. the disc on whose parallel faces the associated pads exert their frictional action, is not integral with the wheel hub, but engages with it, in concentric circumferential alignment, by means of a mobile coupling which allows radial thermal expansions and axial displacements of the disc itself. Said coupling is constituted by the reciprocal engagement of asoleradials, obtained on the floating disc, and of centering bushes, engaged on the hub, with the interposition of cup springs with axial elastic deformation.

In this way, the disc braking band can expand radially, under the effect of the heating generated by the braking friction, and can move axially along the aforesaid bushings to align with the braking pads when they close.

With the adoption of the floating discs described above, the operating conditions of the braking system are certainly improved since the axial elastic deformation of the cup springs allows a corresponding axial movement of the braking disc when the braking pads are closed. by operating on the braking surface of the friction disc with a calliper grip, they cause it to temporarily self-align with them. at each release of the pads in opening due to the elastic return of the axially oriented disc springs.

So that, taking into account the aforementioned effect and the fact that the machining tolerances of the braking band with respect to the support hub, however narrow and precise, can produce axial oscillations during the rotational motion of the wheels, contact can occur over time. discontinuous sliding between disc and pad, even when the brake is not activated.

This phenomenon produces variations in thickness, measurable along any circumference included in the working area of the pads.

If the differences in thickness of the braking band reach high values, low frequency vibratory phenomena still arise during braking actions, and the phenomenon tends to increase more and more over time, making it essential to replace the disc, even if it is not very worn.

The purpose of the present invention is to eliminate the aforementioned drawbacks. The invention, as it is characterized by the claims, solves the problem by means of an axial positioning device of the braking band for disc brakes, in particular for motorcycle brakes, by which the following results are obtained: the braking disc is engaged in concentric circumferential alignment to the corresponding wheel hub by means of a mobile coupling that guarantees its radial expansion, under the thermal effect produced by the braking friction, and its axial positioning, with permanence in this position assumed both during the actions braking that after releases; the coupling consists of the mutual engagement of radial slots, present on the braking disc and of centering and driving bushes, engaged on the hub, cooperating with elastic means, or springs with a shaped profile, with folded side arms for centering and of transversal positioning.

The advantages achieved by the present invention essentially consist in the fact that the movable coupling between the parts ensures correct and free expansion in the radial direction of the braking disk, under the thermal effect produced by the friction between the braking surfaces of the brake disk and of the pads, and guarantees a correct and lasting self-centering of the braking band, with respect to the position assumed by the opposing braking pads and acting astride the band itself, both during the active phases and during the rest phases, so that with the brake shoes open, in any way pads can enter into sliding relationship with the surfaces of the braking bands since the resulting clearance between the spaced parts is equal on both sides and is certainly higher than the machining tolerances between the band and hub; this condition prevents the occurrence of any phenomenon of vibrations, regardless of the natural oscillations of the band deriving from the processing tolerances.

The invention is described in more detail below, according to an embodiment given only by way of non-limiting example, with reference to the attached drawings, in which: Fig. 1 is an overall perspective view of a first preferred form of the elastic element with shaped profile, for centering,

Fig. 2 represents the assembly sequence of the parts making up the invention,

Fig. 3 represents a front view, with an enlarged detail of the positioning of an elastic element or spring, in a radial slot of a brake disc,

Figures 4 and 5 show, in front and plan view, the positioning of a spring, with respect to the brake disc and the corresponding hub,

Fig. 6 represents the front view of a brake disc, applied to its hub by means of the invention and combined with the brake pads included in the relative caliper,

Fig. 7 shows an enlarged view of the braking disc / hub coupling with the relative axial self-centering clearances, and

Fig. 8 represents the overall perspective view of a second preferred form of the elastic element with shaped profile, with double annular body.

The figures show a device for axial positioning of the braking band for disc brakes, particularly suitable for applications on motorcycles, in which the braking band (1) is engaged in concentric circumferential alignment with the corresponding wheel hub (2) by means of a mobile coupling. , floating.

Along the internal circumference (3) of the braking band (1) there are equidistant radial surfaces (4) in which through slots are obtained, radial (5), normal to the braking surface, coaxially coupled to the threaded holes (6) made along the outer crown (7) of said hub (2).

The coupling between the braking band (1) and wheel hub (2) is achieved by aligning said radial slots (5) with said threaded holes (6), introducing calibrated bushes (8) into said slots (5), aligning them with bushings the through hole (9) of elastic elements or springs (10) and binding these components together by means of screws (11) coupled to the threaded holes (6). The aforementioned coupling provides that between the aligned parts: band (1) / hub (2), pre-established lateral axial clearances "b" remain, such as to allow axial displacements of the band (1) (fig.7).

The heads (12) of the screws (11) abut against or upper planes (13) of the calibrated bushings (8), with the interposition of the annular part (24) of the shaped springs (10); the thickness of the bushings (8) is substantially greater than the thickness of the braking band (1) which is thus able to perform axial movements "b" along the bushings themselves and in the two opposite directions, while maintaining its concentric position with respect to the hub (2), thanks to the mutual radial arrangements of the aforementioned slots (5) combined with the calibrated bushings (8). From the aforementioned annular part (24), of the springs (10), an appendix (25) extends radially, which then assumes an orthogonal orientation until it constitutes, in its final part, a centering end (17). From the orthogonal section (25 ') of said appendix (25), on the other hand, two side elastic arms (14) extend, opposite each other, which fold back assuming an arched leaf spring shape.

The axial displacements "b" that the braking disc (1) can perform are regulated and limited by the adhesion action that the folded and elastic lateral arms (14) exert on the braking surface, against which they interact.

The springs (10) have the function of allowing the braking band (1) to be able to slide both radially, to compensate for the thermal expansion deriving from the braking friction produced by the pads (16) on the braking band of the disc (1), and axially, according to the dimensions "b", normal to the braking surface, due to the contact and centering between the disc (1) itself and the pads (16).

During vehicle operation, in conditions of non-activated braking system, each spring (10) creates an axial constraint due to friction due to the force F, allowing the disc to slide axially, centering itself between the pads (16). The forces F1 are constant and do not vary as the position of the band varies in the radial or axial direction.

The second function performed by the springs is to ensure the angular positioning of the braking band (1), with respect to the calibrated driving bushes (8). The orthogonal upper end (17) of each spring (10), in fact, engages in a projection or hole (18) made on the vertical support surface (19) of the wheel hub (2). The holes (1B) are made with an eccentricity "e", with respect to the axis of symmetry of the springs (10), in a direction such that the orthogonal ends (17) which engage in them, preload the arms (14) of the springs with an additional force F2. In correspondence with each spring (10), a difference is thus obtained between the tangential forces applied to the two folded and elastic side arms (14), which creates a moment, with respect to the rotation axis, capable of bringing the braking band into contact (1) with the bushes (8) in the tangent points (20), where the forces are discharged during braking. This prevents play between the braking band (1) and bushes (8), which could cause abnormal noise and / or wear. When the braking system is activated, the opposing pads (16) are pushed, by the hydraulic pistons included in the caliper (22), against the parallel braking bands of the disc (1). The braking action, exerted in a substantially equal manner by the two opposing pads, acts on the parallel faces of the disc (1) in equal measure; so that, in the event of a possible misalignment of the competing parts, the disc is axially pushed towards the center of the system, sliding on the bushes (8), in one direction or the opposite within the range of games "b" provided, and sliding on the folded and elastic side arms (14) of all the springs. Once the centered position of the system has been reached, and the offset existing between the disc and the pads has been canceled, the disc remains in this correct position centered with respect to the pads (16) and no longer at the axial clearances "b", even after the braking action has been released. , as there is nothing that contrasts this condition but, on the contrary, the very adherence of the elastic arms (14) to the lateral surfaces of the slots (5) favors its persistence. Basically, after the first settling braking actions, the pads (16) - disc (1) system remains perfectly centered with constant "a" play between the active surfaces of the pads themselves and the parallel surfaces of the disc braking surface (1 ), to the detriment of the "b" games set up for this way of operating. These clearances "a" correspond to the actuation stroke of the thrust pistons of the pads and being well above the machining tolerances of the braking band and hub, they totally exclude the possibility that vibratory phenomena of the type known as " judder ".

In figure 8 the elastic element or spring (10 ') is shown in a second preferred embodiment thereof, in which the structure, substantially the same in shape and purposes as that (10) already described, also comprises a second annular part ( 24 ') parallel, aligned and integral with the first annular part (24), spaced from it substantially by the thickness of the bush (8) and competing with the bush itself for the constitution of the axial clearances "b".

This configuration has the main function of making the structure of the spring more rigid and avoiding its eventual twisting under the effect of braking actions.

While the present invention has been described and illustrated according to an embodiment thereof given solely by way of non-limiting example, it will be evident to those skilled in the art that various modifications to the structure and / or shape of the elastic retaining and guiding elements, upon coupling of the parts, to the means of pushing and maintaining the shot may be made, without thereby leaving the SOUTH scope and purpose.

Claims (8)

CLAIMS 1) Device for positioning the braking band, for floating-type disc brakes, in which the braking band (1) and the wheel hub (2) are coaxially engaged with each other by means of axial bushes (8) which are constrained to said hub (2) passing through radial slots (5) obtained on said braking band (1), characterized in that it comprises shaped elastic elements (10) which are interposed between said fixing means and which include lateral extensions (14) and central (17) which enter into sliding adherence and centering relationship with the lateral surfaces (15) of said radial slots (5), of said band (1), and with the support surface (19) of said hub (2 ), which has a greater thickness than said band (1). 2) Device according to claim 1 characterized by the fact that the shaped elastic elements (10) consist of one or two aligned annular bodies (24) combined with radial appendages (25) which fold orthogonally (25 ') and form a protruding end centering (17); said orthogonal extensions (25 ') comprising opposite lateral arms (14) which assume an arched, elastic leaf-spring configuration. 3) Device according to claims 1 and 2, characterized in that the shaped elastic elements (10) enter into coaxial engagement relationship with said bushings (8), and the relative fastening means (11), through their annular parts (24) (24 ') and that said elastic lateral arms (14) opposed and shaped like a leaf spring enter into frictional engagement relationship with the lateral surfaces (15) of said radial slots (5) of the braking bands (1). 4) Device according to claims 1 to 3, characterized in that said opposite elastic lateral arms (14), of said elastic elements (10), enter into frictional engagement relationship in seats or radial slots (5), normal to the braking surface. 5) Device according to claims 1 to 4, characterized in that said elastic elements (10) constitute the angular positioning means, with respect to the braking band (1), through the eccentric couplings "e", of the centering end ( 17) with the projections or holes (18) of the hub (2). 6) Device according to claims 1 to 5, characterized by the fact that the engagement by friction between the elastic lateral arms (14), opposite and shaped like a leaf spring, and the lateral surfaces (15) of said radial slots (5) of the braking band (1), cannot be influenced by the radial position of the disc itself and by its radial thermal expansion, but is compatible with the axial displacements "b" for centering the braking, normal to the braking surface of the same disc. 7) Device according to claims 1 to 6, characterized in that the axial self-centering movement "a", normal to the braking surface, and the axial movement "b" on one side or the opposite side, of the braking band (1) with respect to the centering bushings (8) and with respect to the wheel hub (2), it is a function of the position assumed by the braking pads (16) during the first actuations; said self-centering "a" for axial positioning of the band (1), with respect to said pads (16) being permanent over time, but not fixed, ie it can vary the position on the basis of new positions that the pads can assume. 8) Device for axial positioning of the braking band for floating type disc brakes as described with the reservation expressed in the last sentence of the descriptive part, as illustrated by way of example, according to the preceding claims and for the specified purposes.