"PLUG FOR BRAKE CALIPER" * * * * *

Technical Field of the invention

The present invention relates to a caliper for brakes that can be applied to members moving relative to each other.

In particular, the present invention relates to a caliper for disc brakes, for example for bicycles and motorcycles.

Background Art

As it is known, the disc brake comprises a disc solid to the wheel of the vehicle and a brake caliper mounted, by means of suitable supports, to a part of the same vehicle.

The caliper is provided with one or more small pistons which close up onto the disc to exert the braking action by means of either a pedal-operated pump mounted close to one of the footboard of the motorcycle, or a lever disposed on the handlebar of same motorcycle.

In particular, the small pistons are in contact with the respective pads, which are the components actually exerting the braking action on the disc. The pads are usually made from sintered, organic or combined materials (semimetallic, carbon, ceramic...) having high friction capacity and being resistant to high temperatures .

After the release of the brake control by the user, the small pistons and, thus, the pads, return approximately to the initial position, due also to the action exerted by an elastic means interposed therebetween.

It is a growing trend to produce calipers for disc brakes in one-piece component. This embodiment allows achieving a greater structural resistance of the whole braking system, but gives however problems relative to the accessibility necessary for assembling the components and, in general, when carrying out the machining operations inside the body of the same caliper (seats of pistons and gaskets, hydraulic

channels ... ) •

To overcome this drawback it results therefore crucial to form at least a hole for access into the containment body of the brake caliper. Said hole must then be hermetically sealed by a plug.

In the known brake calipers, this plug is applied on the caliper body, usually in alignment with the axis of the pistons and fixed, for example, by means of threaded elements on the containment body, thereby requiring added material with consequent increase of the caliper's overall dimensions .

The known calipers for brakes are not therefore without drawbacks . A first drawback lies in the fact that in the known calipers, the presence of the plug needs the said added material to form a housing for the same plug, such provision giving rise to an asymmetry of the caliper that may generate braking forces not perfectly balanced between the piston acting in the caliper portion which includes the plug, and the piston acting in the opposite portion.

A second drawback, again caused by the presence of added material provided for housing the plug, is given by the fact that a caliper having such added material can be mounted on the vehicle only on a single part of the wheel. In particular, the caliper must be mounted on the vehicle so that the added material will face the outside of the wheel in order not to interfere, for example, with the spokes of the wheel of a bicycle or motorcycle. Disclosure of the Invention The object of the present invention is therefore to overcome the above said drawbacks by providing a caliper for brakes suited for an easy and practical assembly on both sides of the wheel of a bicycle or motorcycle, without creating any interference with the elements of the same wheel.

The technical characteristics of the invention, according to the above objects, are clearly set forth in the appended claims, the advantages of the same invention being more evident from the detailed description that follows with reference to the accompanying drawings, which show an exemplary and non-limiting embodiment thereof. In the drawings :

- Fig. 1 is a first section view of a brake caliper according to the present invention; - Fig. 2 is a second section view of a brake caliper according to the present invention;

- Fig. 3 is a side view of brake caliper shown in the previous figures;

- Fig. 4 shows in detail a preferred embodiment of a plug used in a brake caliper according to the present invention; and

- Fig. 5 shows in detail a possible type of piston used in a brake caliper according to the present invention. Described herebelow, according to the accompanying drawings and reference being made in particular to Figs. 1 to 3, is a brake caliper comprising a one-piece containment body 2 having an external surface and being substantially symmetrical to a plane "X". The containment body 2 comprises, on a first portion 2a, a cavity 20 allowing access to the inner regions of the brake caliper to ease the assembly upon production (for example of pistons 3, 5) and any service operation to be carried out also after the assembly of the caliper on the vehicle or a generic member to _^ _Jqe slowed down and/or stopped. More precisely, the containment body 2 results substantially symmetrical to the plane "X" save for the supports 15.

In particular, the containment body 2 exhibits two opposite portions 2a, 2b with equal overall dimensions along the direction "Y" and comprising the same components (pistons

3, 5, gaskets 4, 16), except for a plug 1 included only in the first portion 2a in order to seal tightly a cavity 20 housing the piston 3, as shown in Fig. 1.

The plug 1 has an external surface Ic and can be fixed in the cavity 20 to close it off.

Advantageously, the tight sealing of the cavity 20 is made by fixing the plug 1, the latter being screwed into a threaded hole 8 formed directly in the containment body 2 (as shown in Fig. 5) . Under a closing condition of cavity 20, the external surface Ic of plug 1 remains fully within the overall dimensions defined by the external surface of the containment body 2. More precisely, with reference to Fig. 4, the upper surface "S" of plug 1 results flush with, or at a level below the upper surface ^λλ P" of the first portion 2a of containment body 2.

The second portion 2b of containment body 2 is in fluid communication with the first portion 2a and comprises a cavity 17 in which a second piston 5 is disposed for acting along the same axis "Y" of piston 3 but in opposite direction.

The second piston 5 slides inside the cavity 17 and in contact with a sealing gasket 16 disposed in a seat formed on the same containment body 2.

The first piston 3 and the second piston 5 are associated with respective pads 6 (of known type) which transmits the friction force onto a disc 7 (of known type) solid to the wheel and interposed between said pads . Preferably, a brake caliper according to present invention also comprises at least one gasket 4 disposed in a seat inside the cavity 20 so that, when the plug 1 is screwed into the containment body 2, a first end Ib will result into abutment on the same gasket 4, that is, will provide a positional reference for the gasket 4.

Upon the assembly, preferably prior to the positioning of the plug 1 for the closing of cavity 20, the piston 3 is disposed inside the same cavity 20 for operatively sliding at least partially inside the plug 1 and in contact with the gasket 4 or close thereto.

The assembly and service operations are made easier by the fact that the distance "d" between the pistons 4 and 5 is such as to allow the exit of one of the two pistons without removing the plug 1. In particular, the piston 3 slides directly onto the inner surface Id of the plug 1, the latter carrying out therefore the function of cylinder for the piston 3. Described hereunder, with reference in particular to Fig. 4, is a preferred embodiment of the plug 1 which comprises on its upper end Ia a concave surface 10 allowing the formation of the seat for inserting a tool to be used for the screwing/unscrewing of the same plug 1 (also shown in Fig. 3) , said concave surface being substantially counter shaped to a convex surface 9 formed on the upper end 3a of piston 3.

In this embodiment, the plug 1 also comprises on its end Ia one or more sealing gaskets 12 which allow maintaining a tight-seal condition of the cavity 20 and making more difficult the spontaneous unscrewing of same plug. This solution makes it possible to obtain a reduction of the overall dimensions and weights of the caliper, which is most important for example in the bicycle and motorcycle field. A brake caliper according to the present invention also comprises supports 15 for fixing the same brake caliper on the vehicle or on any member to be slowed down and/or stopped, for example threaded connections, or through slots, of a type known per se and therefore not to be described in greater detail. The brake caliper is connected with a user-operable brake

control (for example a footboard or a lever) by means of at least one connection conduit 13, 14 holding a fluid. In operation, a brake caliper according to the present invention, when the two cavities 17, 20 result filled with fluid introduced by the connectors 13, 14, the actuation of the brake control member by the user generates an almost simultaneous increase of hydraulic pressure, on the external ends (with respect to axis "X") of the two pistons 3 and 5 in the first 2a and second 2b portion of the containment body 2, so as to generate at least one motion component along the axis "Y".

The movement of pistons 3 and 5 close to each other puts the pads 6, associated therewith, in contact with the brake disc 7, thereby generating a braking force necessary for slowing down and/or stopping the vehicle.

The moment the user releases the brake control, the pistons 3 and 5, and respective pads 6, move back to the initial position, thereby facilitating the detachment of the brake disc 7 through the action of an elastic means 11 (in the illustrated example being a spiral spring) interposed between the pads 6.

The present invention achieves important advantages . A first advantage lies in the fact that a brake caliper according to the present invention allows disposing the plug 1, which is capable of tightly sealing the cavity 20, fully within the internal dimensions of same cavity 20, thereby achieving a caliper without added material and thus symmetric to the plane "X", and of less overall dimensions with respect to the known brake calipers. The obtainment of symmetric caliper brings about also significant advantages both in terms of balance of braking forces and possibility of assembling the caliper with the portion 2a of containment body 2 (that is, the portion comprising the plug 1) either on the inner or on the outer side of the vehicle's wheel.

The invention thus conceived is evidently suited for industrial application; the same invention can also be subjected to several modifications and changes falling within the scope of the inventive idea; moreover, all the parts may be replaced by other elements technically equivalent .