CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application of PCT International Application No. PCT/IB2019/051419, having an International Filing Date of Feb. 21, 2019 which claims priority to Italian Application No. 102018000002973 filed Feb. 23, 2018, each of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a disc brake caliper body, preferably of fixed caliper type, which can be used on vehicles and in particular, but not necessarily, intended for high-performance motor cars.

The present invention further relates to a disc brake caliper and to a disc brake assembly having a caliper body of the type specified above.

BACKGROUND OF THE INVENTION

In a disc brake, the brake caliper is generally arranged straddling the outer peripheral margin of a brake disc, adapted to rotate about a rotation axis (A-A) defining an axial direction (X-X). In a disc brake, a radial direction (R-R), arranged substantially orthogonal to said axial direction (X-X), and a punctually tangential or altogether circumferential direction (C-C), orthogonal to both said axial direction (X-X) and said radial direction (R-R), is further defined.

It is known that a caliper body of fixed caliper disc brake can be associated with a disc so as to maintain its distance from the disc unchanged. Said known caliper body comprises a first half-body, adapted to accommodate first means for generating a braking action, arranged facing a first braking surface of an outer side of said disc, as well as a second half-body, adapted to accommodate second means for generating the braking action, arranged facing a second braking surface of an inner side of said disc. Said first and second half-bodies are connected, by means of fixing means, to two bridge elements arranged straddling the disc.

The expression “outer side” means the side of the disc brake assembly which faces towards the outside of the vehicle when it is fitted on the hub and stub axle, or hub-holder, of the wheel. Similarly, the expression “inner side” means the side of the assembly which faces towards the inside of the vehicle when it is fitted on the wheel hub.

As known, the discs for disc brakes comprise a bell, adapted to associate the disc with a vehicle hub, from which an annular portion, named braking band, intended to cooperate with pads of a caliper, extends.

Said braking band is intended to cooperate with calipers for disc brake adapted to apply a braking action on the vehicle, whereby applying, by means of pads, friction on opposite surfaces of the two plates, named braking surfaces.

It is known that during the operation of the brakes, the friction between the pads of the brake calipers and the braking surfaces of the braking band generates a high amount of heat which needs to be disposed of.

Indeed, the generated heat determines the onset of many undesired phenomena, such as, for example, the deformation of the braking band, the formation of cracks on the braking surfaces or localized state transformations of the material constituting the braking band which, in turn, lead to the deterioration of the braking band itself.

As mentioned above, during the braking of a vehicle, the significant and high forces which bias the caliper body are a clamping action and a braking action. These actions are produced by the means adapted to generate the braking action, e.g. at least one pair of cylinder and piston assemblies, accommodated in the half-bodies, the pistons of which act by means of the pads on the opposite braking surfaces of the disc.

The clamping action of the pads against the braking surfaces of the disc is directed axially and is balanced by the structure of the caliper body which is arranged straddling the disc. In particular, such action is contrasted by the bridge elements which, by embracing the disc, form closed force loops. This action biases the caliper body, determining a spreading of the bridge elements, or, in other words, a bending of the caliper body along the axes in tangential direction, or with concavity about radial axes.

The braking action is instead directed tangentially and in particular in the rotation direction of the disc. This action is transmitted by the disc to the pads and contrasted by shoulders provided in the bridge elements, so as to be released onto the supporting means of the caliper body which are rigidly coupled, for example, to a stub axle or hub-carrier of a wheel of the vehicle. This action biases the bridge elements whereby also deforming portions thereof necessary to connect the half-bodies. Furthermore, the braking action is released onto the supporting means only on the side of the caliper body facing the inner side of the disc, whereby also determining a bending of the caliper body about the radial axes.

The aforesaid actions are notoriously not uniformly distributed on the caliper body and are of a magnitude which is variable over time, whereby causing, in addition to deformations of the caliper body which are sometimes unacceptable for a correct operation of the disc brake, also vibrations and undesired screeching.

Therefore, the need is strongly felt to suggest a caliper body of fixed caliper disc brake, which has such structural and functional characteristics as to overcome the aforesaid disadvantages described with reference to the prior art and in particular to lighten the caliper body but at the same time strengthen the bridge elements arranged straddling the disc brake and at the same time simplify the construction of the caliper body and especially the working of the thrust device housings, e.g. of the cylinders adapted to accommodate the thrust pistons adapted to bias the brake pads.

In some prior art solutions, especially for medium-to-low-performance vehicles, it is known to use a disc brake of the floating caliper type, in which a caliper having a single piston or multiple pistons but all on the same side of the disc brake is supported in the condition that the brake caliper can be freely moved with respect to a supporting element, or bracket, which is fixed to a fixed part of a vehicle, e.g. to the hub-holder, to support the pair of brake pads and with a sliding constraint which allows the supporting element to float or move freely with respect to the disc. As mentioned, in the case of the aforesaid disc brake with floating caliper, the piston is arranged only on one side of the rotor, i.e. the piston is arranged only on the inner side, or vehicle side, of the disc.

In the case of high-performance vehicles, opposed piston disc brakes have become common, because they can produce an excellent braking force, by virtue of their greater efficiency. In the disc brake of the opposed piston type, pistons are provided on both sides of a disc brake. During braking operations, a pair of pads is pushed against both opposite braking surfaces of the disc brake rotor by both opposite pistons. In this opposite piston disc brake, the rotor of the brake disc is interposed between the cylinders adapted to accommodate the pistons and the open sides of the cylinders are opposite to one another.

Therefore, in these high-performance vehicles, the need is strongly felt for a caliper body of great stiffness able to maintain the orthogonality between the bridge elements and the half-bodies facing the braking surfaces of the brake disc.

Document GB2214581 by Freni Brembo S.p.A. shows a single-block brake caliper body solution with opposed pistons or fixed caliper body.

Indeed, this single-block caliper body has a structure in which the elongated portions facing the disc brake have a plurality of cylinders integrated in a single body. However, the structure described in the aforesaid patent publication is disadvantageous in that it requires time and complex special methods for working the cylinders and assembling the disc brake of the opposed piston type made in a single block. Therefore, it is impossible to avoid an increase in production costs.

In order to simplify the working of the cylinders, solutions are known in which the calipers are made in two halves and then joined.

In this case, the body having a plurality of cylinders is divided into half-bodies having an attachment portion, or attachment half-body, to be connected to a stationary portion of a vehicle, e.g. a hub-holder, and also having a cylinder on the inner front side, and a portion or outer body having a cylinder on the outer front side. After both bodies have been worked to form the cylinders required in them, the half-bodies are connected and fixed to one another by bolts.

Examples of these caliper bodies are known from GB936222 by DUNLOP RUBBER CO; U.S. Pat. No. 3,261,429 by Bendix Corp.; U.S. Pat. No. 5,538,105 by DAYTON WALTHER CORP and U.S. Pat. No. 5,819,886 by Robert Null.

However, in the known structure mentioned above of the caliper in two parts, the bolts for attaching and fixing the inner body and the outer body to one another receive a braking torque which is given by the outer brake pad and biased by the pistons of the outer body, braking action generated by the friction caused between the outer side face of the rotor, or disc brake, and the outer pad in the braking process. It is therefore necessary for the bolts to withstand this braking torque. Therefore, the diameters of the bolts must be large in size, to the extent of increasing size and weight of the caliper body. The weight of the disc brake, which is supported in an end portion of the angle portion of a vehicle, or corner, becomes an unsprung weight, i.e. not suspended by elastic and/or damping elements. Accordingly, even when the weight of the disc brake increases only slightly, the running performance of a vehicle is also strongly biased by the increase of unsprung weight.

Therefore, the need is strongly felt also to reduce the overall weight of the fixed brake caliper.

This need, combined with the contrasting one of stiffening the caliper body and further the contrasting need of simplifying the working of the thrust means housings, has led to some known solutions which however do not optimize these conflicting requirements.

For instance, there is the solution of U.S. Pat. No. 6,260,670 by AKEBONO BRAKE IND of two-part caliper, the solution of EP1303708B1 by Freni Brembo S.p.A. of three-part caliper, the solution of U.S. 2009236187 of CONTINENTAL TEVES AG & Co OHG of three-part caliper, the solution of U.S. 2006231354 by WARREN, the solution of U.S. 2010170755 by Robert Biggs and the solution of WO201491423 by Franco Iorio.

The solution of U.S. Pat. No. 5,515,948 by Gilliland also shows a caliper in multiple parts connected together by calibrated pins extending straddling the disc brake. This known solution, in order to allow to have the desired strength and mechanical rigidity, requires however calibrated pins and connections between the different parts of considerable diameter, whereby causing considerable radial dimensions of the caliper as a whole, resulting in a solution which is not very suited to the current requirements of a large-size brake disc rotor adapted to increase the range of action of the braking action which leaves very little space between itself and the inner surface of the rim of the vehicle wheel. Furthermore, this known solution which requires large-size steel pins is not optimal for the need of reducing the overall weight of the brake caliper.

Therefore, the need remains strongly felt to provide a fixed caliper body in separable parts but which ensures an accurate alignment of the bridges and of the elongated elements which ensures a perfect orthogonality between the components, which orthogonality does not create problems for pads, such as jamming and non-uniform wear thereof.

Therefore, the need remains strongly felt to improve the accuracy with which the connection elements, or bridges, are connected to the half-bodies, in order to stiffen the parallelogram created by the half-bodies and the bridges. The further need is felt to provide a supporting surface of the bridge connection elements either parallel or perpendicular to the releasing plane of the braking action.

The problem underlying the present invention is thus to provide a fixed caliper body and a caliper, which have structural and functional characteristics such as to satisfy the aforementioned requirements and at the same time solve the drawbacks mentioned with reference to the prior art.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a fixed caliper body, a brake caliper and a braking device in which the aforesaid mutually conflicting requirements are achieved and optimized.

This and other objects and advantages are achieved by a caliper body and a brake caliper as described and claimed herein.

Advantageous embodiments are also described.

The analysis of this solution shows that the suggested solution allows obtaining a caliper body which is light but at the same time able to support high braking actions without being excessively deformed and without exceeding in its overall dimensions.

Furthermore, the suggested solution allows considerably simplifying the working operations of the half-bodies of the caliper.

Furthermore, the suggested solution allows obtaining a braking comfort much higher than the solutions of the prior art, and consequently a reduction of the vibrations and in particular an absence of the vibrations which cause screeching.

