FLOATING BRAKE DISC

Technical field

This invention relates to the field of braking systems, in particular the object of this invention is a floating brake disc. Background art

There are prior art floating brake discs comprising a cap and a brake strip mutually connected rotationally by the interposition, in suitable seats, of a plurality of bushings designed to transmit the rotational forces between the brake strip and the cap, allowing at the same time the floating of the brake strip on the cap. One of the defects of this system is that it results in a significant wear of the bushings themselves, subjected to considerable forces, forcing the user to carry out frequent and time-consuming replacements.

Also known are floating brake discs wherein the brake strip is rotationally constrained to the cap by means of a shape coupling, for example notched, without the interposing of bushings, between the two parts. These brake discs are generally known as "pulling" brake discs.

Disadvantageously, the free floating of the brake strip on the cap results in problems of vibrations and undesired interactions between brake strip and grippers in the presence of axial and radial forces, in particular of inertia forces, which can be caused, for example, following bends or irregularities in the ground. These interactions result in safety problems, due to the possible unforeseeable effects of undesired contacts between the brake strip and gripper, and greater wear of components.

In this context, the technical purpose which forms the basis of this invention is to propose a floating brake disc which overcomes at least some of the above-mentioned drawbacks of the prior art.

Aim of the invention More specifically, the aim of this invention is to provide a floating brake disc which can improve the safety and reduce the wear of the known brake discs.

The technical purpose indicated and the aims specified are substantially achieved by a floating brake disc comprising the technical features described in one or more of the appended claims.

According to one aspect, this invention relates to a floating brake disc comprising a cap, which can be connected to a wheel of a vehicle in such a way as to have an axis of rotation in common with the wheel itself, and a brake strip. The cap comprises a first connecting portion and the brake strip comprises a second connecting portion, mutually shaped to match the first connecting portion. The first and second connecting portions can be coupled to determine a direct shape coupling between the cap and the brake strip. The shape coupling rotationally constrains the brake strip about the axis of rotation of the cap and allows a translation of the brake strip along the axis of rotation.

The floating brake disc comprises a constraining mechanism connected to the cap and associated with the brake strip.

According to an aspect of the invention, the constraining mechanism causes an axial constraint, acting along the axis of rotation of the cap, between the brake strip and the cap.

The constraining mechanism comprises at least one elastic element having a compliance such as to allow, under force, an axial movement of the brake strip relative to the cap. The axial movement is directed along the axis of rotation and dampened by the elastic element.

According to an aspect of the invention, the brake disc comprises a plurality of seats each for a corresponding elastic element.

The seats are preferably formed as recesses or spot facing or niches for the corresponding elastic element.

This invention may comprise one or more of the following features.

Preferably, the constraining mechanism determines a radial constraint, acting along a radial direction of the cap, between the cap and the brake strip. The radial constraint limits a movement of the brake strip relative to the cap and is configured to determine an elastic opposing action and damping on the radial movement.

Preferably, a radial compliance of the elastic element determines the above-mentioned elastic opposing action and radial damping.

Preferably, the elastic element is interposed between the cap and the brake strip. The brake strip and the cap have mutually connecting surfaces with the elastic element.

Preferably, the constraining mechanism comprises a clamping system determining an end stop of the axial movement of the brake strip.

Preferably, the elastic element is interposed between the brake strip and the clamping system. The brake strip and the clamping system have mutually connecting surfaces or surfaces of contact with the elastic element.

Preferably, the elastic element is interposed between the clamping system and the cap. The clamping system and the cap have mutually connecting surfaces with the elastic element.

Preferably, the clamping system is configured to impart an axial preloading to the elastic element.

Preferably, the brake disc has, at the above-mentioned mutually connecting surfaces, at least one recessed seat, for housing the elastic element, and respective contact surfaces. The recessed seat and the contact surfaces are configured to limit the maximum deformation in the elastic range of the elastic element. Preferably, the maximum deformation is 0.10 mm.

Preferably, one between the first and second connecting portions comprises a plurality of teeth and the other between the first and second connecting portions has a plurality of recesses which can be mutually coupled to the teeth.

Preferably, at least one between the cap and the brake strip comprises at least one shoulder designed to abut on the other between the cap and the brake strip determining an end stop to the axial movement of the brake strip.

Preferably, the elastic element is a cup-shaped spring.

Brief description of the drawings

Further features and advantages of this invention are more apparent in the detailed description below, with reference to a preferred, non-restricting, embodiment of a floating brake disc as illustrated in the accompanying drawings, in which:

- Figure 1 is a front view of a floating brake disc in accordance with this invention;

- Figure 2 is a cross-section of the floating brake disc through the line ll-ll of Figure 1 ;

- Figure 3 is the enlarged detail "A" of the cross-section of Figure 2;

- Figure 4 is a front view of the detail of Figure 3 wherein several elements have been omitted to highlight others;

- Figure 5 is a perspective exploded view of a floating brake disc according to this invention;

- Figure 6 shows the exploded view of Figure 5 from a different angle.

Detailed description of preferred embodiments of the invention

With reference to drawings, the floating brake disc according to this invention is indicated generically by the numeral 1 .

The floating brake disc 1 comprises a cap 2, a brake strip 3 and a mechanism 4 for constraining the brake strip to the cap.

The cap 2 is configured for the connection to a wheel of a vehicle, not illustrated, in such a way as to share an axis "X" of rotation, with the above-mentioned wheel. The cap 2, moreover, extends rotationally about an axis, preferably coinciding with "X". In the embodiment illustrated, the cap 2 defines a plurality of first holes 5 for connection to the wheel, radially arranged around the axis "X", designed to house clamping means for the connection with the above-mentioned wheel.

The cap 2 comprises a first connecting portion 6, whilst the brake strip 3 comprises a second connecting portion 7, mutually shaped to match the first connecting portion 6. The first connecting portion 6 and the second connecting portion 7 are mutually shaped to match to determine a direct shape coupling between the cap 2 and the brake strip 3.

The expression direct shape coupling is used to mean a coupling between the two parts which does not require third elements for transferring the loads, for example bushings. The direct shape coupling may also comprise further elements interposed between the cap 2 and the brake strip 3 which are not structurally necessary for the above-mentioned shape coupling and for the transfer of the tangential loads, such as for example damping elements having the function to distribute more uniformly the loads.

The above-mentioned shape coupling is configured to rotationally constrain the brake strip 3 to the cap 2, in particular constraining the brake strip 3 to rotate about the axis "X" when the cap 2 rotates about the axis "X". The coupling according to the invention is also configured to allow an axial movement of the brake strip 3 relative to the cap 2 along the axis of rotation "X", so as to form a floating disc. In the preferred embodiment of the shape coupling according to the invention, one of either the first connecting portion 6 and the second connecting portion 7 has a plurality of teeth 8, whilst the other has a plurality of recesses 9 which can be mutually coupled to the teeth 8.

In the embodiment illustrated, the teeth 8 have equal circumferential extension to each other, equivalent to the distance between two successive teeth 8. The latter embodiment is advantageous since it allows a better distribution of the shear forces.

In at least one embodiment, one between the cap 2 and the brake strip 3 comprises at least one shoulder 10 configured to abut on the other between the cap 2 and the brake strip 3, determining an end stop to the above-mentioned axial movement of the brake strip 3.

In the embodiment illustrated, each shoulder 10 is located between two teeth 8 of the cap 2 and operates in synergy with the above-mentioned teeth 8. In this case, the constraint imposed by the shoulders 10 ensures the correct positioning of the teeth 8 in the reciprocal recesses 9 and, vice versa, the constraint imposed by the teeth 8 ensures the correct positioning of the brake strip 3 relative to the cap 2 and to the shoulders 10.

The constraining mechanism 4 is connected to the cap 2 and determines an axial constraint between the cap 2 and the brake strip 3, acting along the axis of rotation "X" of the cap 2, which limits the axial movement of the brake strip 3 relative to the cap 2.

In one embodiment, the constraining mechanism 4 determines a radial constraint between the cap 2 and the brake strip 3, which limits a radial movement of the brake strip 3 relative to the cap 2.

Preferably, the constraining mechanism 4 comprises a clamping system.

In the preferred embodiment, the clamping system comprises a contact ring 1 1 clamped to the cap 2; moreover, in the embodiment illustrated, the clamping system also comprises a plurality of bolts 1 1 a, inserted in respective second holes 1 1 b defined in the contact ring 1 1 and in the cap

2, for clamping the contact ring 1 1 to the cap 2.

Advantageously, the constraining mechanism 4 comprises a plurality of elastic elements 12, preferably cup-shaped springs, having an axial compliance such as to allow, under force, an axial movement of the brake strip 3 relative to the cap 2. The above-mentioned axial movement is directed along the axis of rotation "X" and is opposed elastically and dampened by the elastic elements 12.

In a preferred embodiment, the elastic elements 12 are interposed between the brake strip 3 and the clamping system.

For example, the elastic elements 12 are interposed between the brake strip 3 and the contact ring 1 1 .

In alternative embodiments not illustrated, the elastic elements comprise, for example, helical springs, elastomers, rubber bearings and the like. Advantageously, a radial compliance of the above-mentioned elastic elements 12 allows a radial movement of the brake strip 2 relative to the cap 2. The above-mentioned radial movement is directed along a radial direction of the cap 2 and is opposed elastically and dampened by the elastic elements 12.

In the preferred embodiment illustrated by way of example, the elastic elements 12 are interposed between the teeth 8 of the brake strip 3 and the contact ring 1 1 .

Preferably, the contact ring 1 1 is configured to impart an axial preloading to the elastic elements 12.

Preferably, the contact ring 1 1 imposes an end stop to the axial movement of the brake strip 3, opposite to that imposed by the shoulders 10, with which the contact ring 1 1 operates in synergy. The two end stops imposed, respectively, by the shoulders 10 and by contact ring 1 1 each determine an end stop position of the brake strip 3, allowing the floating between the above-mentioned end stop positions.

As already mentioned, in the embodiment illustrated the plurality of elastic elements 12 is interposed between the contact ring 1 1 and the brake strip 3. In this embodiment the brake strip 3 remains, at rest, in the limit position, in contact with the shoulders 10 of the cap 2. Under force, the brake strip 3 can move in the direction of the contact ring 1 1 compressing the elastic elements 12. In other equivalent embodiments, not illustrated, the elastic elements 12 are interposed between the brake strip 3 and the cap 2; in this case the brake strip 3 is, at rest, in the end stop position in contact with contact ring 1 1 and, under force, can move in the direction of the cap 2. In this case, seats for the springs may be formed in the brake strip 3 or in the cap 2. In a further embodiment not illustrated, the elastic elements 12 are interposed, in respective seats, both between the brake strip 3 and the cap 2 and between the brake strip 3 and the contact ring 1 1 , determining a rest position of the brake strip 3 which is intermediate between the two end stops and, under force, an axial movement of the brake strip 3 towards the cap 2 or towards the contact ring 1 1 .

In embodiments which are not illustrated, which are alternative but equivalent, the contact ring 1 1 is clamped to the brake strip 3 and floats with it. In this case, moreover, the brake strip 3 comprises the shoulders 10 and the end stops of the axial movement of the brake strip 3 are determined respectively by the shoulders 10, when in contact with the cap 2, and by the contact ring 1 1 , when in contact with the cap 2. In this case, the elastic elements 12 are interposed between the contact ring 1 1 and the cap 2, or between the brake strip 3 and the cap 2, or both between the contact ring 1 1 and the cap 2 and between the brake strip 3 and the cap 2. These three configurations determine, respectively, a possibility of axial movement under force equivalent to that allowed by each of the three configurations described above.

In other alternative solutions not illustrated, the constraining mechanism 4 comprises two contact rings 1 1 , each determining an end stop to the axial movement of the brake strip 3. In this case, no shoulder 10 is necessary on the cap 2 or on the brake strip 3.

If two contact rings 1 1 are provided, it is possible to provide a first embodiment wherein the above-mentioned contact rings 1 1 are clamped to the cap 2. In this case the brake strip 3 is floating between the two contact rings 1 1 , whilst the elastic elements 12 are interposed between the brake strip 3 and a contact ring 1 1 or between the brake strip 3 and both the contact rings 1 1 . In the first case, the brake strip 3 is, at rest, in contact with a contact ring 1 1 and can move, under force, towards the other contact ring 1 1 , compressing the elastic elements 12. In the second case, the brake strip 3 is, at rest, in an intermediate position between the two contact rings 1 1 and is free to move, under force, towards one of the above-mentioned contact rings 1 1 . If two contact rings 1 1 are provided, it is possible to provide a second embodiment wherein the above-mentioned contact rings 1 1 are clamped to the brake strip 3; in this case, the contact rings 1 1 are integral with the brake strip 3 and floating with it. Each contact ring 1 1 determines, making contact with the cap 2, an end stop to the axial movement of the brake strip 3. In this case, the elastic elements 12 are interposed between a contact ring 1 1 and the cap 2 or between both the contact rings 1 1 and the cap 2. These two configurations determine, respectively, a possibility of axial movement under force equivalent to that allowed by each of the two configurations described above.

All the solutions described above comprise, in the bodies between which the elastic elements 12 are interposed, the presence of mutually connecting surfaces 13 with each of the above-mentioned elastic elements 12 and mutual contact surfaces 14 designed to determine the above- mentioned end stop. Preferably, these mutually connecting surfaces 13 or the contact surfaces 14 comprise recessed seats 20 are configured for housing the elastic elements 12, for example cup-shaped springs.

The seats 20 are formed, in the embodiment illustrated by way of example, in the outer surface of the brake strip 3, in particular of the teeth 8, and are configured for housing respective cup-shaped springs.

Each seat 20 is as recess, in the example illustrated, in the corresponding tooth 8 of the brake strip 3.

Each seat 20 is, for example, formed by removing material from the brake strip 3, for example by milling.

Generally speaking, each seat 20 is in the form of a niche or spot facing for the respective elastic element 12.

The respective configuration of the mutually connecting surfaces 13 and the contact surfaces 14 determines a maximum extension of the axial movement allowed by the brake strip 3. Preferably, the above-mentioned maximum extension is limited to the elastic range of deformation of the elastic elements 12 and the most favourable solution comprises a maximum floating of approximately 0.10 mm.

The invention achieves the set aim by overcoming the disadvantages of the prior art.

By adopting a so-called "pulling" brake disc it is possible to avoid the wear which is typical of the bushing systems since the clamping elements, for example consisting of bolts 1 1 a, do not undergo shear stress, unlike the bushings.

Moreover, the presence of the elastic elements 12 makes it possible to oppose and dampen possible vibrations in an axial or radial direction caused by the stresses acting on a brake disk with the "pulling" configuration.

In the embodiment illustrated by way of example, the ring and the cap are rigidly connected by the bolts and the brake strip can move between the cap and ring suitably opposed by the cup-shaped springs each housed in a respective seat.