Abstract:
A disk brake for a motor vehicle having a caliper (1), a carrier (2) which fixed to the vehicle and a pad (41) located between a tip (10) on the caliper (1) and a disk (D). The pad (41) being fitted with a spring (5) which holds the pad against the tip (10) of the caliper (1). The spring (5) bears elastically on inclined surfaces of the tip (10) of the caliper (1) and is subjected to a torque (C--C) which urges the spring (5) to rotate about an axis (X) and to continually urge the spring (5) against the carrier (2).

Description:
The present invention relates to a disk brake for a motor vehicle, comprising: two brake elements which can move with respect to each other, one of which is a caliper straddling a brake disk and the other of which is a carrier fixed to the vehicle; clamping means comprising a tip of the caliper, the tip consisting of a flat shaping of the caliper formed facing a first face of the disk, and a cylinder connected to the caliper and closed by a piston turned toward a second face of the disk; guide means allowing the caliper to slide with respect to the carrier under the effect of urging from the clamping means; and first and second friction pads turned respectively toward the first and second faces of the disk, clamped between the piston and the tip of the caliper and moved in an axial direction of the piston by urging from the clamping means until they are applied against the disk; each of the two pads exhibiting two substantially flat faces, the first of which is partially covered with a friction material, and two lateral lugs; the first and second lugs of the first pad interacting with first and second respective supports of the carrier; and the first pad carrying, on its second face, an elongate spring, with two main branches, which points in a tangential direction of the disk and is intended to hold the first pad on the tip of the caliper and elastically clamps the tip of the caliper between the respective free ends of its two branches and the second face of the first pad. 
     BACKGROUND OF THE INVENTION 
     Devices which comply with this definition, which encompasses a number of disk brakes, are well known in the prior art, as shown, for example, in the documents U.S. Pat. No. 4,082,166 and EP-A-0 112 255. 
     One of the problems posed in disk brakes, particularly those which use pads of the type identified previously, lies in the difficulty of giving the pad, particularly the so-called &#34;outboard&#34; pad which is distant from the piston, a predetermined and reproducible position. 
     This difficulty is particularly troublesome if the pad is attached to the carrier and/or assumed to bear continuously against it, poor positioning of the pad with respect to the caliper then giving rise upon braking to a transient condition which is both noisy and ineffective. 
     The invention falls within this context and its object is to provide a braking device which, although it is of simple structure, ensures that the outboard pad has a predetermined and reproducible position with respect to the carrier. 
     SUMMARY OF THE INVENTION 
     To this end, the brake of the invention, which in other respects complies with the preamble hereinabove, is essentially characterized in that the ends of the two main branches of the spring point toward the tip of the caliper and bear elastically against respective bearing surfaces of the tip of the caliper, in that the bearing surfaces are inclined both with respect to the axial direction of the piston and with respect to the first face of the disk, and in that the bearing surfaces exhibit opposite slopes with respect to the axial direction of the piston, so as partially to convert the elastic bearing of the free ends of the branches of the spring on the bearing surfaces into a torque urging the first pad to rotate about an axis parallel to the axial direction of the piston. 
     For example, the bearing surfaces may be formed by the edges of two respective V-shaped grooves cut in the tip of the caliper, and the free ends of the branches of the spring are preferably cut into a point with a rounded end. 
     The features of the invention are particularly useful in a brake in which the first lateral lug of the first pad at least, and the first support of the carrier, exhibit partially complementary profiles which fasten the first pad with respect to the carrier and in which the second lateral lug of the first pad at least, and the second support of the carrier, exhibit respective regions in contact with each other and ensuring that the first pad bears continuously against the carrier. 
     According to one possible embodiment of the invention, the lateral lugs of the first pad may be rounded. 
     Irrespective of the embodiment, it may be advantageous further to provide for the spring to include an additional branch bearing against the tip of the caliper in order to urge the first pad in translation. 
     Further features and advantages of the invention will emerge clearly from the description thereof given hereafter by way of non-limiting indication with reference to the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a disk brake in accordance with the invention; 
     FIG. 2 is a front view of the disk brake of FIG. 1, viewed in the direction identified by the arrows 2--2 of FIG. 1; 
     FIG. 3 is a view similar to that of FIG. 2, distinguishable therefrom merely in that it illustrates, in a less complete and more diagrammatic fashion, another embodiment of a disk brake in accordance with the invention; 
     FIG. 4 is a part section view in the direction of the arrows 4--4 of FIG. 3, and enlarged; 
     FIG. 5 is an enlarged view of the spring illustrated in FIG. 3; and 
     FIG. 6 is a part section view in the direction of the arrows 6--6 of FIG. 3, and enlarged. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown especially in FIGS. 1 and 2, the invention relates in general to a disk brake, such a brake conventionally comprising: two brake elements which can move with respect to each other, one of which is a caliper 1 straddling a brake disk D and the other of which is a carrier 2 fixed to the vehicle; clamping means comprising a tip of a caliper 10, the tip consisting of a flat shaping of the caliper formed facing a first face Di of the disk D, and a cylinder 3 connected to the caliper 1 and closed by a piston 31 turned toward a second face D2 of the disk D; guide means, such as guide pins 11, 12, connected to the caliper and sliding in bores 21, 22 of the carrier, to allow the caliper 1 to slide with respect to the carrier 2 under the effect of urging from the clamping means; and first and second friction pads 41 and 42. 
     These first and second friction pads 41 and 42 are turned respectively toward the first and second faces D1 and D2 of the disk D (FIG. 1), are clamped between the piston 31 and the tip 10 of the caliper 1 and are capable of being moved in the axial direction A of the piston 31 by an increasing pressure in the cylinder 3, by virtue of which the piston 31 on the one hand and the tip 10 of the caliper 1 on the other hand apply them against the disk D. 
     Each pad such as 41 or 42 includes two substantially flat faces such as 411, 412 and 421, 422, the first 411, 421 of which is partially covered, in a central region, with a friction material F (FIG. 1). 
     Each pad further includes, on either side of this central region, two lateral lugs such as 41a and 41b, the lugs of the first pad at least interacting with the respective supports 23a, 23b of the carrier 2. 
     Furthermore, on its second face 412, the first pad 41 carries an elongate spring 5, with two main branches 51 and 52, which is oriented in a tangential direction of the disk D, is intended to hold the first pad 41 on the tip 10 of the caliper, and elastically clamps the tip 10 of the caliper between the respective free ends 510, 520 of its two branches and the second face 412 of this first pad. 
     It is important, for the invention, for the spring 5 to be secured to the second face 412 of the first pad 41 in a way which prevents any relative rotation of this spring and of this pad, and for example by means of two spaced-apart anchoring points 53, 54. 
     According to the invention, the ends 510, 520 of the two main branches 51, 52 of the spring 5 point toward the tip 10 of the caliper (FIGS. 4 and 6) and bear elastically against respective bearing surfaces 130, 140 of the tip 10 of the caliper. 
     Moreover, these bearing surfaces 130, 140 are inclined both with respect to the axial direction A of the piston and with respect to the first face D1 of the disk, and exhibit opposite slopes with respect to the axial direction A of the piston, so as partially to convert the elastic bearing of the free ends 510, 520 of the branches 51, 52 of the spring 5 on the bearing surfaces 130, 140 into a torque C--C urging the first pad 41 to rotate about an axis X parallel to the axial direction A of the piston and, in this case, coincident with the axis of the piston in FIGS. 2 and 3. 
     As FIGS. 4 and 6 show, the bearing surfaces 130, 140 may be formed adequately by the edges of two respective V-shaped grooves 13 and 14 cut in the tip 10 of the caliper. 
     Furthermore, the free ends 510, 520 of the main branches 51, 52 of the spring 5 are preferably cut into a point with a rounded end in order to be able to slide better over the bearing surfaces 130, 140. 
     The invention is particularly advantageous in the case, illustrated in FIGS. 2 and 3, in which the first lateral lug 41a of the first pad 41 at least, and the first support 23a of the carrier 2, exhibit partially complementary profiles which fasten the first pad 41 with respect to the carrier 2, and in which the second lateral lug 41b of the first pad 41 at least, and the second support 23b of the carrier 2, exhibit respective regions in contact with each other and ensuring that the first pad bears continuously against he carrier. 
     In point of fact, in such a configuration, in which the disk D is assumed to have a favoured direction of rotation indicated by the arrow R, the torque C--C which urges the first pad 41 to rotate about the axis X has the effect of reinforcing the holding of each of the two ends of this pad by the carrier. 
     By way of indication, and as shown in FIG. 3, the lateral lugs 41a, 41b of the first pad at least may be rounded. 
     Irrespective of the shape of these lugs, it may further be advantageous, as illustrated in FIGS. 2, 3 and 5, for the spring 5 to include an additional branch 55 bearing against the tip 10 of the caliper, in order to urge the first pad 41 in translation and reinforce its contacts with the carrier.