FR2461847A1 - THERMALLY BALANCED DISC BRAKE ROTOR - Google Patents

Abstract

THE ROTOR 14 INCLUDES A PREFERRED MATERIAL OR EARTH IN ONE PIECE WITH THE OUTER ROTOR PERIPHERY, GENERALLY NEAR THIS PERIPHERY, WHICH ACHIEVES THERMAL BALANCE WITH THE CENTRAL CAP PART OF ROTOR 22. IN A BRAKE ROTOR A VENTILATED DISC, THIS BALANCING MASS MAY BE ARRANGED IN THE ROTOR WALL CLOSEST TO THE CAP PART, BY PROPORTIONING THE THICKNESS OF WALL 18 AT A POINT GIVEN AT THE RADIAL DISTANCE AT THE CENTER OF THE ROTOR. IN A MASSIVE ROTOR, THE THERMAL BALANCE MASS MAY BE ARRANGED NEAR THE ROTOR PERIPHERY BEYOND THE ROTOR WALL ZONES BROWN BY THE SKATES. THE INVENTION MAY ALSO BE APPLIED BY PROVIDING AN UNSWEPED SIDE WALL ZONE OF THE ROTOR NEAR ITS OUTER PERIPHERY BY REDUCING THE RADIAL WIDTH OF A BRAKE PAD, WHICH HAS THE EFFECT OF CREATING A ZONE WHICH OPERATES AS A SOURCE. COLD.

Description

The present invention relates to disc brakes.

  ques and, more particularly, disc brakes in which a mass of thermal equilibrium is placed on the rotor or disc. This thermal equilibrium mass acts as a cold source so as to achieve equilibrium with the cold source formed by the support and by the mounting structure which is used to fix the rotor or disc to the

wheel hub.

  The heat of friction and the dissipation of heat

  their vehicle disc brakes is known to be

  precisely cyclical. The brakes are engaged intermittently

  tence and most often relatively infrequently

  quente to stop the vehicle, and this cycle includes

  important time intervals during which the

  friction heated parts can cool down The mass of a solid disc brake is a source

  significant and accessible cold in which the heat

  released along the walls of the disc by friction with the brake pads can be transferred. However, the

  support structure which represents an im-

  bearing, generally located near the inner edge of the disc having no corresponding cold source or

  compensation on the outer edge of the disc, will be at the

  gine of a radial temperature gradient across the dis-

2. that '.

  Prolonged application of disc brakes

  naturally extracts significant amounts of heat which

  can be better dissipated by incorporating a variety of

  ventilation ducts arranged radially inside the disc, which is then called the rotor. (Although the term "disc brake" is commonly used to generally refer to both solid rotor brakes and ventilated rotor brakes, it should be noted that it is correct

  to use the expression "disc" when it comes to

  only a massive brake, and the expression "rotor" in the case of a ventilated brake. This distinction is generally

  respected in all the following description, except however

  when the repetition of the words "disc" and "rotor" would obviously be redundant, or in the case where the expression "disc brake" is generically used to designate a brake comprising a planar and circular member in tight rotation

  in friction by a pair of opposite brake linings).

  The radial channels provide a transfer surface for

  additional heat and air circulation inside

  rotor. A ventilated rotor will generally dissipate heat into the surrounding air more quickly than a solid disk due to its larger heat transfer surface and superior air circulation. Compared

  to a unified mass of a massive disc, the interior walls

  res and exteriors of a ventilated rotor represent mas-

  its thermals which are found in thermal environments

  different miques insofar as they are separated by a plurality of radial ribs. In addition, the hub of the

  rotor and / or mounting structure are generally fa-

  in one piece with (or attached to) at least one

  of the two walls of the rotor and represent a thermal mass

  that or significant cold source. Thus, a ventilated rotor is also subjected to radial temperature gradients

  in the adjacent wall or connected to the mounting structure

age and support.

  The object of the present invention is to provide a

246 1847

  3. brake rotor or disc comprising a thermal equilibrium mass which acts as a cold source so as to compensate for the

  mass and therefore the cold source supplied in a manner

  inherent in the rotor mounting structure or

  than. As will appear, the balance mass can be cast in one piece with the disc or rotor, or be attached to the rotor or disc in an appropriate step of the

  manufacturing process by any means of fixing

  appropriate material. In addition, the material of the balancing mass

  bre can be, but it is not necessary, identical to the material of the disc or rotor itself. For example, if space is an important parameter, a material with high specific heat can be used. In other applications, the use of a light material may be desirable. All these variants of mass forming a cold source to counterbalance the mass forming a cold source

  of the rotor or disc support structure are con-

  considered to fall within the scope of this invention

  tion. In a ventilated rotor, the balance mass can be placed on the wall of the rotor closest to the support means, generally the outer wall, so that

  the thickness of the outer wall increases with its distance

  this radial in the center of the rotor. As a variant, the mass for-

  mant cold source can be arranged along a wall of the rotor so as to obtain thermal equilibrium with that of the rotor support structure, and to minimize

  the radial temperature gradients.

  Alternatively, the ventilated rotor, or solid disc, may comprise a mass or material on the periphery which is not in contact with the brake shoe. This can

  be obtained either by reducing the area of the rubbing zone

  between the brake shoe and the rotor wall or

  only by decreasing the radial width of the shoe, which

  provides an unswept ring around the periphery

  external rie of the rotor or disc which functions in cold source, either by adding a material of any 4. shape around the periphery of the disc. The distribution (i.e. the cut) of the peripheral mass can be adjusted to be adapted to the particular conditions

space and thermal balance.

  The object of the present invention is therefore to provide a brake rotor or disc which has a

  minimum radial temperature gradient.

  Another object of the present invention is to provide a ventilated brake rotor having a minimum radial temperature gradient which can be produced by

  classical and current techniques.

  The present invention will be clearly understood from the

  reading of the following description made in conjunction with-

  attached drawings in which: Figure 1 is a perspective view of a ventilated disc brake and rotor according to the present invention; Figure 2 is a fragmentary sectional view of an assembly consisting of a ventilated brake rotor and a caliper taken along line 2-2 of Figure 1;

  Figure 3 is a fragmentary perspective view

  re of a ventilated brake rotor according to the present invention, representing the radial air passage channels;

  Figure 4 is a fragmentary perspective view

  cover of a ventilated disc brake rotor according to the present invention, representing another embodiment of the mass distribution and of the radial air passage channels; Figure 5 is a schematic sectional view of a portion of a ventilated brake rotor, showing the general theory of heat transfer according to the invention; Figure 6 is a fragmentary sectional view of a solid brake disc according to the present invention; Figure 7 is a fragmentary sectional view of another embodiment of a solid brake disc according to the present invention; Figure 8 is a fragmentary sectional view of another embodiment of a solid brake disc according to the present invention; and 5. Figure 9 is a fragmentary sectional view of another embodiment of a solid brake disc

according to the present invention.

  In connection with FIG. 1, a disc brake assembled according to the present invention is generally designated by the reference 10. The assembly 10 comprises a

  assembled caliper 12 and an assembled rotor 14. The rotor as-

  kit 14 includes a rotor part 16 having walls

  exterior and interior generally flat and parallel

  îo 18 and 20, respectively. The rotor 14 comprises at or

  be a frustoconical cap 22 which is generally cast

  in one piece with part 16. The support structure

  port, or hat part 22, defines a plurality of openings

  vertices 24, which cooperate with a plurality of bolts 26 and other components of a wheel hub 28 so as to allow the fixing of the rotor 14 to the hub 28 in the conventional manner. The support structure of the rotor part 16 as well as the means making it possible to attach it to the wheel hub 28 can take various forms and be manufactured by various manufacturing processes in addition to the

  processes described and shown. For example, the structu-

  support re may consist of a protruding part

  inwardly facing, flat, of a rotor or disc mounted axially by sliding on a shaft by means of a spline connection, of a separate attached part which is linked to the rotor or disc by any suitable fixing means, including by casting in one piece, or from a structure having a U-shaped section which is

  attached to the periphery of the disc or rotor. The present invention

  tion applies in all the preceding cases and in

many other types of mounting.

  Now in connection with FIGS. 1 and 2, the stirrup 12 generally has the shape of a C, and comprises a stirrup bridge 30 connecting an outer leg 32 to a

  inner leg 34. The bridge 30 extends across the par-

  rotor tie 16 and is positioned and held there by guides (not shown) which are placed parallel 6.

  to the axis of the rotor 14, which are fixed to an an-

  crage 35. The guides constitute a floating assembly for

  the caliper 12, according to the conventional practice of disc brakes

  than. The inner leg 34 of the stirrup 12 defines a cylinder

  dre 36, inside which is disposed a piston 38 directed towards the rotor part 16. According to classical practice,

  pressurized hydraulic fluid is introduced into the cy-

  lindre 36, which has the effect of advancing the piston 38 towards the rotor part 16. Adjacent to the mouth of the cylinder 36 is an annular groove 40 which serves as a seat for an annular seal 42. The seal 42 is preferably made of an elastomeric material such as rubber and prevents leakage of the hydraulic fluid from the cylinder 36 The piston 38 includes an annular groove 44 which serves as a means

  for maintaining the part of complementary shape of a sou-

  anti-dust flounder 46. The bellows 46 forms a seal in

  one piece, molded from an elastomeric material such as rubber

  cabbage. The bellows 46 forms a seal on the periphery of the piston 38, relative to the caliper 12, while allowing a significant relative axial movement between them. An outer disc brake pad 48 and an inner pad

  disc brake 50 are slidably arranged on the plate

  anchor 35 and are in friction contact with the outer wall 18 and the inner wall 20 of the part

16 rotor.

  As appears, or will appear, the present invention does not relate to the stirrup 12 and its components

  associates, and the previous description was simply for

  purpose than to be representative of the components with which

  it can optionally be combined. The present invention

  tion can be practiced with a wide variety of calipers and piston shapes as well as with other

  energy sources, for example with pneumatic devices

  ticks, mechanical or electrical. Furthermore, since

  the structure and function of stirrup 12 and its components

  associated health are classic and therefore well con-

  naked to those skilled in the art, we will not proceed to a description

7.

more complete of these.

  In connection with Figures 2,3, part 16 of

  rotor comprises an outer wall 18 and an inner wall

  lower 20, as described above. Part 16 is ventilated and, as such, has a plurality of radially arranged channels 54 and an identical plurality

  ribs 56 which extend transversely between the pa-

  outer king 18 and the inner wall 20 of this part 16. According to the present invention, the inner wall 20, or more generally the wall which is farthest from the mounting structure or hat section 22 and is

  separated by the ribs 56, has a uniform wall thickness

  form. The outer wall 18, or more generally

  In general, the wall of the part 16 closest to the mounting structure or cap part 22 has a thickness which increases with the distance from the center of the rotor 14. The mass

  wedge-shaped outer wall 18 thermal balance

  mica the mass of the cap portion 22, which

  puts to minimize the radial temperature gradients at

  through the outer wall 18 of the rotor part 16.

  Again, in connection with FIG. 2, and more particularly with FIG. 3, it appears that the aug- '

  indication of the thickness of the outer wall 18 driving

  does a corresponding reduction in the width of the air passage channels 54. If it is assumed that the lengths of the inlet and outlet of the channels 54 are equal, such a reduction in the channel width

  54 results in a substantially lower outlet

  laughing, and by an obstacle to the air flow in the channels 54. This obstacle can, of course, be eliminated by maintaining the cross-sectional area of the outlet orifices of the air passage channels substantially equal to or greater than

  the cross-sectional area of the intake openings of these

  nals. By adjusting the cross-sectional area of the ribs 56, one can maintain a cross-sectional area of the passage channels

  air substantially constant or increasing in the direction

  dial. Thus it is possible to obtain a thermal equilibrium of the 8. cold source of the mounting structure and the maintenance of a good air flow in the radial air passage channels.

  FIG. 4 represents another embodiment.

  tion of a rotor having the reference 60. It will appear that a ventilated rotor such as part 16 does not need to include substantially rectangular ribs, nor substantially rectangular air passage channels according to the present invention. In this regard, the rotor 60 of this embodiment of the present invention comprises an inner wall 62 having a constant thickness at its thinnest part, and an outer wall 64 having a thickness increasing towards the outside. The rotor 60 comprises air passage channels 66 of generally elliptical section.

  main axes of the channels 66 are aligned circumferentially-

  ment around the periphery of the rotor 60. These major axes, on the inner surface of the rotor 60, are parallel to the axis of this rotor and therefore perpendicular to the

  main axes of channels-66 on the outer surface of the rotor.

  It will be noted that such a configuration also makes it possible to

  maintain air passage channels having a running surface

  eg constant or increasing in the radial direction, in addition

  of a mass forming a cold source and that it allows equal-C.

  to obtain reduced radial temperature gradients

  in the wall of the rotor 60 adjacent to the mounting structure

  ge, while maintaining a good air flow in the channels 66. It will be noted on the other hand that neither the conical wall of the

  preferred rotor, adjacent to the bonnet part with its ca-

  generally rectangular air passage channels, nor the notched conical wall of the other embodiment of the

  rotor with its generally elliptical air passage channels

  These do not constitute limitations of the field of application of the present invention. On the contrary, any configuration

  walls of a rotor (or disc) which has a mass

  mant cold source to balance the mass and the effect of

  cold source of the rotor mounting structure (or

  9. que) in order to minimize the radial temperature gradients inside the rotor (or disc) is considered

  as falling within the scope of the present invention.

  Figure 5 is another representation of the thermal equilibrium obtained by placing the mass on a wall of a ventilated brake rotor in order to balance

  the inherent cold source formed by the structure of my-

  rotor stage, and thus minimize the temperature gradients

  radial erasure inside the rotor. It will be noted that the calculations indicated later are only given as

  example, and simply to explain the pre-

  invention. The accuracy of the results is proportional

  born from the apparent complexity and sophistication of

  mathematical analysis. The results should be considered

  res as constituting a first approximation which can be improved by using a mathematical analysis

  more empirical and empirical, as well as experimental

  such as dynamometer tests.

  Figure 5 shows an outer wall of

  rotor and bonnet section, which are similar to the

  corresponding parts which could be used in a vehicle brake. The ribs and the inner wall of the rotor are shown in dotted lines only for reference, and do not enter into the following calculations since their characteristics of heat transfer and temperature gradient are supposed to have a negligible effect on the heat transfer characteristics

  in the radial and temperature gradient direction of the pa-

  rotor king adjacent to the mounting structure. As noted, the bonnet part of the rotor, that is to say the elements 1, 2 and 3 in FIG. 5, constitutes a cold source for the frictional heat released on the surface of the external wall. adjacent to the rotor (item 4) and

  absorbed by this wall. Element 5 in Figure 5 shows

  feels a mass of conical shape arranged on the wall of

  rotor which, with the mass of element 4, balances the source

  this cold formed by elements 1, 2 and 3, of section 10.

hat.

  The following calculations quantify this relationship

  of equilibrium and determine a width, or thickness, ap-

  T of the triangular element 5 for dimensions

  given elements 1, 2, 3 and 4 of the cap part and the rotor part, respectively. The radii and other dimensions of the elements of the cap part and of the rotor are represented in FIG. 5. Pappus' theorem according to which the volume of a solid of revolution is the product of the generating area by the distance traveled

  by the center of gravity of the area is used to calculate

  ler the volumes of the various elements and so to calculate

  implicitly the mass and specific heat of these elements

  since it is assumed that the density and heat

  their specific rotor are constant.

  For element 1 (hat part), the area (A1) is equal to 12.7 mm x 61 mm, i.e. A = 775 mm2, the radius (Y1) of the center of gravity is = 38 + 30.5, i.e. = 68.5 mm and the distance traveled by the center of gravity (D1) = 137 n mm. According to Pappus' theorem, the product A D is equal to the volume (V1) of element 1 and A1D = 106 n cm. Similarly, with regard to element 2, the surface (A2) is equal to 12.7 mm x 50.8 mm, that is to say = 645 mm 2; the radius of the center of gravity (Y2) is equal to 99 mm + 6.35 mm, i.e. 105.4 mm and the distance traveled by the center of gravity (D2) is 210.8 n mm. The product A2D2 is equal to 136 n cm, which corresponds to the volume (V2) of element 2. With regard to element 3, the area (A3) is equal to 12.7 mm x 30.5 mm = 387 mmn, the radius of the center of gravity (Y3) is equal to 99 mm + 15.2 mm, i.e. 114.25 mm and the distance traveled by the center of gravity (D3) is

  228.5 n mm. The product A D is equal to 88 n cm, which corresponds to

  3 3 pond to the volume (V3) of element 3. Finally, the total volume (and proportionally the mass) of elements 1, 2 and 3 (V123) is equal to

V1 + V2 + V3 = 330 n cm.

  By carrying out the same calculations for elements 11. 4 and 5 of the rotor part, the area of element 4 (A4) is equal to 12.7 x 66 mm = 838 mm; the radius of the center of gravity (Y4) is 129.5 + 33 = 162.5 mm and the distance

  traversed by the center of gravity (D4) is equal to 325 T cm.

  The A4D4 product is equal to 272 n cm. Similarly, with regard to element 5, the area (A5) is equal to 0.5 x 66 x Tmm2 33 Tmm; the radius of the center of gravity (Y5) is 129.5 + 0.667 x 66 = 173 mm, and the distance traveled by the center of gravity (D5) is 347 n mm. The volume (V5) of

  element 5 is equal to product A5D5, i.e. 11,418 mm3.

  For there to be a static thermal equilibrium, the volume (and the mass) of elements 1, 2 and 3, must be approximately equal to the volume (and the mass) of elements 4 and 5, that is to say:

V1 + V2 + V3 V4 + V5

  By replacing V with their values, we get

T - 5 mm.

  Thus, a value equal to 5 mm for the width ma-

  ximuim of the triangular element 5 of the rotor part is a first approximation of the thickness of the mass which makes it possible to obtain a thermal equilibrium in a rotor

  assembled with the dimensions indicated.

  The foregoing description of embodiments

  particular of the present invention has been focused on ro-

  ventilated torso with air passage channels

  tees generally in the radial direction, which are arranged in-

  be the walls of a brake rotor. However, the concept of the present invention, i.e. the placement of a

  ground on the brake disc or rotor for the purpose of compensating

  ser the inherent cold source characteristics of the

  mounting structure, can also be applied to devices

  massive brake ques. As such, the present invention

  provides either a specific formed peripheral extension-

  on the solid disc, or, alternatively, the supply

  brake pad on the side of the disc the more

  che of the mounting structure, either on both sides, which

  is not in frictional contact with the entire surface

  246i847 12. lateral king of the disc but leaves an unscanned peripheral strip. In such a configuration, this surface of the disc, instead of being a source of heat as a result

  friction contact of the brake pad, becomes simple-

  lies an additional mass which functions as a source

  cold to compensate for cold source characteristics

  inherent in the mounting structure.

  Figures 6, 7, 8 and 9 show four pro-

  solid disc wires which can be used for the

  practice of the present invention. Specifically, the fig-

  re 6 describes a solid disc 70 which is fixed to a bonnet part 72 cast in one piece. The party in contact

  by friction of the disc 70 corresponding to the radiating width

  the effective of the brake pads (not shown) is

  signed by the quotation marks having the reference 74. It appears

  rait that the disc 70 extends beyond this swept area.

  Specifically, the outer edge of the disc 70 is oblique and defines a pointed triangular section 76 around its periphery. The triangular section 76, the greater part of the mass of which is disposed near the edge of the disc 70 closest to the bonnet part, constitutes a substantially larger cold source on this side of the rotor than

  on the opposite side, and, proceeds to the thermal equilibrium of the device

than 70.

  Likewise, FIG. 7 represents a first variation

  disc riant 80 having a cap section 82 and

  rotor surfaces scanned 84. Again, the mass represented

  sensed by the reference 86 is placed on the disk 80.

  In a similar way to the embodiment of FIG. 6, the mass 86 is arranged in a non-uniform manner around the external surface of the disc 80 and forms a somewhat larger cold source in this part of the disc.

  closest to the hat portion 82.

  Since, by its nature, a solid disc will tend to have a more uniform temperature than a ventilated rotor, applications may exist where a mass of thermal equilibrium must be added uniformly to 13.

  the periphery of a disc. In addition, a structure of my-

  such that the planar structure extending radially

  described above, if it is fixed substantially in my-

* symmetrically around the axial median plane of the disc, will generally be thermally balanced optimally by a cold source arranged in a corresponding manner. In

  FIG. 8, a solid brake disc 90 comprises a part

  one-piece flat mounting tie 92 as previously described

  cedent. Again, the area in contact by friction of the

  disk 90 is represented by the quotes and the reference-

  ce 94. A ring 96 having a generally rectan section

  gular is arranged uniformly around the periphery of the disc 90. The ring 96 can be cast in one piece or can then be fixed to the disc 90 and can be of the same or a different material as the disc 90. It will be noted that the mass of ring 96 will function relatively uniformly as a cold source with respect to the faces

  left and right of the solid disk 90, as will the par-

  flat mounting tie 92 as a result of the uniform distribution

  me of material around the axial median plane of the disk 90.

  FIG. 9 shows a third embodiment of

  reading of a solid disk 100 comprising a mass available

  seated around its periphery in order to balance thermo-

  only the inherent cold source represented by the

  hat tie cast in one piece 102. In this mode

  of realization, the additional mass has a trian- section

  gular 104 and tends to absorb and dissipate uniformly

  even heat from the left and right surfaces

  of the disc 100 in a similar manner to the ring 96 of the

  cond embodiment shown in Figure 8. It appears

  that the additional mass incorporated is in a dis-

  that massive is in a ventilated rotor, can be arranged

  around the periphery of the rotor in any way

  re compatible with the thermal equilibrium objective of the inherent cold source created by the rotor mounting structure. Once the required characteristics of

  heat transfer for thermal equilibrium have been

- 2461847

  14. blies, the specific material, the specific heat, the mass, the section or the thickness may be a function of considerations such as casting techniques and

  manufacturing, cost or conservation of energy.

  As indicated above, the inventive concept can also be put into practice by reducing the value of the surface on the side of the disc or rotor closest to the mounting structure or on both sides of the disc or rotor in contact by friction with the or

  the brake pads. Referring quickly to the figure

  re 9, the surface swept by the classic brake pad

  is represented on the right and indicated by the reference-

  ce 106. On the opposite side of the disc 100, a reduced friction contact surface, represented by the reference 108, is used for the practice of the present invention, insofar as the non-engaged surface represented by the

  reference 110 is no longer a heat source of friction

  but in fact represents a surface and a mass as-

  company that operates in a cold source. It will be noted that the radial width and consequently the surface in friction contact of the two left and right brake pads can be reduced, providing a cold source on both.

brake disc or rotor surfaces.

  The appreciation of some of the measurement values

  above should take into account that they pro-

  come from the conversion of Anglo-Saxon units into metric units.

  The present invention is not limited to the examples

  ples of realization which have just been described, it is on the contrary susceptible of variants and modifications

  which will appear to those skilled in the art.

246 1847

15.

Claims (6)

CLAIMS l - Ground means in a brake incorporating an assembled rotor comprising a rotor part and a mounting structure, an assembled caliper having brake pads and a means for bringing these pads in contact with the rotor part, characterized in that it is distributed over the rotor so as to thermally balance the mass of the mounting structure, as a result of which the radial temperature gradients inside the rotor are minimized.   2 - Disc brake assembled for motor vehicle   tor, characterized in that it comprises, in combination, an assembled rotor having an axis, an assembled caliper having a pair of brake pads and means connected to the pads for bringing them into friction contact with the assembled rotor,   this comprising a rotor part and a cha-   skin placed in the center, the rotor part having a first circular wall fixed to the cap part and a second circular wall arranged coaxially and spaced along   of the axis of the first wall, and a plurality of ribs   res for connecting the first and second walls, the first wall having an outer surface disposed normally to the axis and an inner surface disposed obliquely to the axis, after which the first wall has a   thickness which increases with the distance from the axis.   3 - Brake according to claim 2, characterized   in that the first wall, the second wall, and the nerves   vures define air passage channels, arranged   radially, of substantially uniform section.   4 - Disc brake according to claim 2,   characterized in that the ribs have a sensitive section-   uniformly over their radial length.   - Disc brake, characterized in that it comprises in combination: an assembled rotor having an axis, an assembled caliper having brake pads and a means for   bring them into contact with the assembled rotor, this rotor   seemingly comprising a rotor part, a centrally placed cap part 16. and a cold source means arranged radially outside the cap part to substantially thermally balance the cold source supplied by the cap part, and minimize the gradients of radial temperature in the rotor part. 6 Disc brake according to claim 5, characterized in that the rotor part is solid and in   that the cold source means comprises a flat material   generally adjacent to the outer periphery of the rotor part.   7 - Disc brake according to claim 6, charac-   terized in that the material has a substantially triangular section.   8 - Disc brake according to claim 6, ca-   characterized in that the material has a substantially rectangular section.   9 - Disc brake according to claim 5, ca-   characterized in that the assembled rotor comprises first and second walls which are distant from each other, radial air passage channels being located between them, the means of   cold source being placed along at least one of the kings.   - Disc brake according to claim 9, ca-   characterized in that the thickness of the cold source means increases with distance from the axis.