Abstract:
A caliper for disk brakes for high-performance cars, which has a high degree of reliability, comprises a body having two side portions and two transverse bridges connecting the two side portions, cylinder-piston units arranged along each side portion, and a circuit for a fluid for cooling the cylinder-piston units, the circuit comprising wells which are formed along the side portions and are of a depth such that they extend substantially as far as the wall delimiting the cylinder-piston units, and which are closed by covers, the circuit also comprising connecting ducts between adjacent wells.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a caliper for disk brakes for motorcars, particularly high-performance cars, of the type comprising a body having two side portions and two transverse bridges connecting the two side portions, cylinder-piston units arranged along each side portion, and a circuit with an inlet and an outlet for a fluid for cooling the cylinder-piston units. 
     As is known, in calipers of the type specified, it is necessary to cool the cylinder-piston units so that the braking fluid does not reach excessively high temperatures which would lead to boiling of the braking fluid and consequently to loss of braking efficiency. 
     In known calipers, although the circuits for the cooling fluid used up to now for preventing the braking fluid from reaching excessively high temperatures are substantially satisfactory, they have recognized disadvantages. 
     For example, there are known calipers which have cooling-fluid circuits constituted by ducts formed in the caliper body during casting. These ducts extend along the side portions of the caliper and their path extends past the walls of the cylinder-piston units. However, this known solution requires the caliper bodies to be produced by casting with the disadvantage of structural complexity of the body. 
     Calipers which have fluid ducts, particularly air ducts, which extend along the cylinder-piston units in the vicinity of the region of contact with the braking pads have also been proposed. However, this latter solution is penalized by the poor heat-removal capacity typical of air, and requires very large ducts. 
     The technical solution of fitting, on the caliper body, elements having ducts through which a cooling liquid, rather than air, is intended to flow, however, have the disadvantage of requiring dimensions which are notably large, although smaller than those of solutions in which the cooling fluid is air. 
     SUMMARY OF THE INVENTION 
     The problem upon which the present invention is based is therefore to devise a caliper of the type specified which has structural and functional characteristics such as to satisfy the above-mentioned need to cool the cylinder-piston units, at the same time overcoming the disadvantages mentioned with reference to the prior art. 
     This problem is solved by a caliper of the type specified which is characterized in that the circuit for the fluid for cooling the cylinder-piston units comprises wells formed along at least one of the side portions, the wells being of a depth such that they extend substantially as far as the vicinity of the wall delimiting at least one of the cylinder piston units, and the wells being closed by covers, the circuit also comprising connecting ducts for putting the wells into fluid communication with one another. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristics and the advantages of the caliper according to the present invention will become clear from the following description of embodiments thereof given by way of non-limiting example and illustrated in the appended drawings, in which: 
     FIG. 1 is a view showing a first embodiment of the caliper according to the invention, in longitudinal section, 
     FIG. 2 is a perspective view of the caliper of FIG. 1 with parts separated, viewed substantially from below and from the rear, 
     FIG. 3 is a perspective view of the caliper of FIG. 1 with parts separated, taken from above and from the rear, 
     FIG. 4 is a perspective view of the caliper of FIG. 1, with parts separated, taken from above and from the front, 
     FIG. 5 is a shows a variant of the caliper of the preceding drawings, in longitudinal section, 
     FIG. 6 is a perspective view of the caliper of FIG. 5, taken from below. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the appended drawings, a caliper for a disk brake intended for a motorcar in general and for a high-performance motorcar in particular, is generally indicated  1 . 
     The caliper  1  comprises a body  2  produced by machining from a solid semi-finished product, for example, from a rolled piece or from a forging of a suitable aluminium alloy known per se. 
     The body  2  has opposed elongate side portions  3  and  4  which are intended to be arranged along opposed sides of a braking band of the disk of a disk brake, not shown in the drawings. 
     The side portion  3  is disposed on the inner side and the side portion  4  is disposed on the outer side of the disk, in conventional manner. 
     Each of the side portions  3  and  4  has a lower peripheral wall  3   a ,  4   a  and an upper peripheral wall  3   b ,  4   b.    
     Two transverse connecting bridges  5  and  6  connect the two side portions  3  and  4  to one another at their respective ends and on the side with the peripheral walls  3   b  and  4   b . These connecting bridges  5  and  6  extend over the braking band of the disk. 
     The caliper  1  is of the fixed type and is intended to be fixed to an axle of the motor vehicle in conventional manner. 
     Cylinder-piston units are arranged along each of the two side portions  3  and  4 . In the embodiment illustrated, four cylinder-piston units  7 ,  8 ,  9  and  10  are disposed in the side portion  3  and four cylinder-piston units  11 ,  12 ,  13  and  14  are disposed in the side portion  4 . 
     The respective cylindrical seat of the cylinder of each cylinder-piston unit  7 - 14  in which the respective piston, not shown, can slide, is indicated  7   a - 14   a.    
     A fluid circuit  15  for a braking fluid supplies all of the cylinder-piston units in conventional manner known per se. 
     According to the present invention, the caliper  1  comprises a fluid circuit  16  for a cooling fluid, for example water, which is provided for cooling the cylinder-piston units  7 - 14  and, more precisely, for cooling the braking fluid operating therein, in order to avoid the danger of boiling of the braking fluid. 
     The fluid circuit  16  for the cooling fluid has a path  17  which extends between two connectors  18  and  19  which constitute the inlet and the outlet for the cooling fluid. 
     Wells are formed in the lower walls  3   a  and  4   a  of the side portions  3  and  4 , preferably by mechanical milling with machine tools. More precisely, according to the embodiment shown in FIGS. 1-4, three wells  20 ,  21 ,  22  and  23 ,  24 ,  25 , respectively, are formed in each side portion  3  and  4 , each in a position between respective adjacent cylinder-piston units. 
     Each well  20 - 25  has a substantially cusp-shaped end  20   a - 25   a  fitted between the respective adjacent cylinder-piston units so that the ends  20   a - 25   a  of the wells are close to the walls delimiting the cylindrical seats  7   a - 14   a  and hence are in a good heat-exchange relationship therewith. 
     The wells  20 - 25  are closed in a leaktight manner by respective covers  20   b - 25   b , for example, by means of conventional screws, or by snap-closure means, or even by gluing, leaktightness being ensured by respective seals  20   c - 25   c.    
     The well  21  and the well  24 , which are deeper, are closed by the covers  21   b  and  24   b . These have appendages  26  and  27  which project into the respective wells  21  and  24  defining respective spaces  28  of limited transverse dimensions. 
     The wells  20  and  21 , as well as the wells  23  and  24  are in fluid communication with one another by means of respective ducts  29 . The wells  21  and  22  as well as the wells  24  and  25  are in fluid communication by means of ducts  30 . 
     The ducts  29  and  30  are produced by drilling along two intersecting axes. 
     The well  22  is put into fluid communication with the well  25  by means of a conventional duct, not shown, and the well  23  is put into communication, by means of a further duct, not shown, with a threaded hole  31 , opening into the inner side of the side portion  3 . The connector  19  is screwed into the threaded hole  31  on the outside of the caliper. A threaded hole  32  is formed in the cover  20   b . This hole  32  which, in practice, is on the outside of the caliper in the same manner as the threaded hole  31 , houses the connector  18  which is screwed therein. 
     It is clear at this point that the circuit  16  for the cooling liquid is constituted by the spaces  28  formed by the covers  20   b - 25   b  with the ends of the respective wells  20 - 25 , by the ducts  29  and  30 , and by the transverse connecting ducts (not shown) which put the well  22  into communication with the well  25  and the well  23  into communication with the threaded hole  31 . 
     All of the covers  20   b - 25   b  are made of aluminium. The appendages  26  and  27  formed integrally with the respective covers  21   b  and  24   b  are also made of aluminium. 
     In operation, the cooling fluid which passes along the path  17  of the circuit  16  flows through the ducts, close to the cylinder-piston units, ensuring that the temperature of the braking fluid is kept below its boiling points. 
     With reference to the embodiment of FIGS. 5 and 6, it will be noted that the circuit for the fluid for cooling the cylinder-piston units comprises, for each side portion  3  and  4 , two wells, indicated  33  and  34 , closed by respective covers  33   b  and  34   b  with seals  33   c  and  34   c . The wells  33  and  34  of the side portion  4  are shown in FIG. 6 without the respective covers. The ends  35  and  36  of the well  33  and of the well  34 , respectively, are shaped so as to be close to the peripheral walls of the cylindrical seats of the cylinder-piston units and the respective covers  33   b  and  34   b  are shaped, for example, by drawing, so as to reproduce the shapes of the ends  35  and  36 . A space  37  formed between the covers  33   b  and  34   b  and the ends  35  and  36  of the respective wells constitutes part of the circuit for the cooling fluid. 
     The connectors  18  and  19  which, in the embodiment of FIGS. 5 and 6, are indicated  18   a  and  19   a , are advantageously positioned in the vicinity of the centreline x—x of the caliper. 
     The main advantage of the caliper according to the present invention lies in its reliability, as well as in maximum strength. 
     Naturally, in order to satisfy contingent and specific requirements, an expert in the art may apply to the above-described caliper many modifications and variations all of which, however, are included within the scope of protection of the invention as defined by the following claims.