Patent Grant
9080624
The invention relates to a motor-vehicle disk brake.
The invention relates to a motor-vehicle disk brake including:
A conventional disk brake includes a fork having at least two generally vertically oriented opposing arms that each have a lateral seat that extends axially and has a C-shaped section opening horizontally towards the opposite arm, and that includes a generally horizontally oriented upper face and a generally vertically oriented lower face.
The seat receives a laminar element made of spring steel that has at least one generally substantially horizontally oriented upper sliding flange that is interposed between the lug of the brake pad and the upper face of the seat, a generally vertically oriented vertical supporting flange that is interposed between the lug of the brake pad and the vertical face, and an elastic retaining flange that is arranged beneath the lug of the brake pad.
In such brakes, increasing the stiffness of the elastic retaining flange to improve retention of the brake pad creates transverse and vertical loads that, on account of the proximity of the elastic flange and of the vertical supporting flange, tend to deform the laminar element.
This prevents a flat-on-flat contact of the laminar element if the lug is not exerting significant pressure on the laminar element, in particular in relation to the vertical supporting flange thereof.
These loads are difficult to control on account of the design of the laminar element. Thus, for low pressures exerted by the lug of the brake pad, the brake pad is in an unpredictable position in relation to the lateral guide seats of the brake pad.
Moreover, during braking, the brake pad follows the rotation of the disk and is subject to a rotational torque exerted substantially on the theoretical center of contact between the brake pad and the disk, while being in transverse horizontal contact.
Theoretically, the resulting forces are aligned but, in consideration of manufacturing variations and uncertainty regarding the actual position of the transverse support between the lug and the laminar element caused by deformation of the element (as explained above), the resulting torque applied to the brake pad (about said theoretical center) may be positive or negative, causing the brake pad to rotate in the direction of rotation of the disk or, conversely, in the opposite direction, which results in unstable behavior of the brake pad.
To overcome this drawback, it is proposed to disconnect the vertical supporting face of the laminar element from the sliding face and from the horizontal supporting face according to a brake design described in the preamble.
Such disk brakes are known in the prior art.
Thus, in such a disk brake, the laminar element has a first lower sliding flange that is theoretically parallel to the second upper vertical supporting flange. Furthermore, the third transverse supporting flange, outside the seat, is orthogonal to the first lower sliding flange.
The first lower sliding flange has an anchoring or attachment tab or tongue that protrudes downwards and that cooperates with the lower face of the seat to anchor itself in this lower face of said seat.
The laminar element positions the lug of the brake pad such as to enable the pad spring to be load-bearing. Preferably, the lower flange provides the corresponding pre-stressing.
The invention overcomes this drawback by proposing a new design of a laminar element able to preload the pad spring when the lug fitted with the spring thereof is inserted and arranged in the laminar element, such as to guarantee optimum contacts between the vertical supporting element of the laminar element and the pad.
Furthermore, the vertical and/or radial instability of the brake pad are advantageously stabilized by disconnecting the axial sliding zones of the brake pads, and by disconnecting the vertical and/or radial return and guide forces.
For this purpose, the invention proposes a disk brake of the type described above, characterized in that the laminar element is elastically deformable between:
According to other features of the invention:
The invention also relates to a method for assembling a disk brake of the type described above, characterized in that it includes:
The invention also relates to a method for replacing a brake pad of a disk brake of the type described above, characterized in that it includes:
Other features and advantages of the invention are given in the detailed description below, provided with reference to the attached drawings, in which:
In the description and claims below, expressions such as “axial”, “transverse” and “vertical” orientations are used as non-limiting references to the dihedral (L, T, V) shown in the figures and in the definitions given in the description, without reference to terrestrial gravity.
In the description below, identical reference signs refer to identical parts or parts having similar functions.
In a known manner, the brake has a fork 11 with at least two opposing arms 14 oriented generally vertically “V”, each of which has a seat 16 oriented axially in the direction “L”, having a C-shaped section opening horizontally towards the opposing arm 14.
Each seat 16 has an upper face 18 oriented generally horizontally and a parallel lower face 20 oriented generally vertically.
The seat 16 receives and seats a laminar element 22 made of spring steel that has at least one generally horizontally oriented upper sliding and supporting flange 25 that is interposed between the lug 26 of the brake pad 12 and the upper face 18 of the seat 16, a vertically oriented vertical supporting flange 28 that is interposed between the lug 26 of the brake pad and the vertical face 20, and an elastic retaining flange 30 that is arranged beneath the lug 26 of the brake pad 12.
In such brakes, if the stiffness of the elastic retaining flange 30 is increased to improve retention of the brake pad 12, the elastic foot 30 induces transverse loads “FT” (globally in a horizontal direction) and vertical loads “FV” that tend, on account of the proximity of the elastic flange 30 and the vertical supporting flange 28, to deform the laminar element, which prevents a flat-on-flat contact of the laminar element, as shown by the dotted lines in
Moreover, during braking, the brake pad 12 follows the rotation “R” of the disk and is subject to a rotational torque “CR” exerted substantially on the theoretical center “O” of contact between the friction lining of the brake pad and a related annular track of the disk, while being in transverse horizontal contact.
The resulting forces (not shown) exerted on the lugs 26 of the brake pad 12 are aligned. In consideration of manufacturing variations and uncertainty regarding the actual position of the transverse support between the lug 26 and the laminar element 22 resulting from deformation of the element 22, the resulting torque applied to the brake pad 12 may be positive or negative, causing the brake pad 12 to rotate in the direction “R” of rotation of the disk or in the opposite direction.
To overcome this drawback, it is proposed to disconnect the vertical supporting flange 28 of the laminar element 22 from the horizontal supporting and sliding flange.
According to this design, as shown in
According to this design, the brake 10 has at least one brake pad 12 with two opposing lateral assembly lugs 26, each of which is received in a related seat 16 of a related arm 14 of the fork 11.
As shown in
Furthermore, the brake 10 includes a pad spring 40 that is attached to the related lug 26 of the brake pad 12.
The pad spring 40 includes, in a known manner, at least one lower sliding branch 42 that cooperates with the lower face 34 of the related seat and that pushes the upper surface 36 of the lug vertically upwards against the upper face 32 of the seat 16.
As shown in
The pad spring 40 also has a curved branch 48 that links the attachment branch 46 to the lower sliding branch 42. This curved branch 48 primarily guarantees the elasticity of the pad spring 40.
Finally, the pad spring 40 includes a free branch 50 that prolongs the lower sliding branch 42 and that closes the profile such as to prevent entanglement of the springs stored for assembly.
The lug 26 is received in the seat 16, interposing a spring steel laminar element 22 related to each arm 14 of the fork 11.
As shown more specifically in
The upper part 52 includes a second upper vertical supporting flange 25 oriented generally horizontally that is interposed between the upper surface 36 of the related lug 26 of the brake pad 12 and the upper face 32 of the related seat 16.
The laminar element 22 also has at least one lower axially oriented supporting part 54 having a third transverse supporting flange 28 that prolongs the sliding flange 24, which extends in a plane orthogonal to the plane of the sliding flange 24, which is arranged in contact with the transverse weight-bearing surface 20 of the arm 14, and that is able to form a transverse stop for the related lower surface 38 of the brake pad 12.
In such a disk brake, the laminar element 22 therefore has a first lower sliding flange 24 that is theoretically parallel to the second upper vertical supporting flange 25.
Furthermore, the third transverse supporting flange 28, outside the seat 16, is substantially orthogonal to the first lower sliding flange 24.
The first lower sliding flange 24 also has an anchoring tongue 56 that is generally cut out of the first lower flange 24, which protrudes downwards, and which cooperates with the lower face 34 of the seat 16 to anchor itself in this lower face 34 of the seat 16, as shown in
Furthermore, the anchoring tongue 56 is cut out such as to be separate from the sliding flange, which makes it possible to select the values of the angles “α” and “β” without compromising the correct positioning of the laminar element in the seat thereof.
The instability of the brake pad and the risk of related noise and/or vibrations are aggravated by increasing rigidity, and subsequently the intensity of the return force exerted by the third flange 28 while, on the other hand, the brake pad is stabilized by “medium” or “strong” braking forces on account of the brake pad being driven by the rotation of the disk.
Advantageously, for a total (bearing) return compression by the third flange 28, the return force FS is less than or equal to the tangential driving force Ftg of a brake pad for an actuating pressure of the brake of 105 Pascals (Pa).
Ftg is equal to the product of μ×P×S in which μ is equal to the friction coefficient of the friction lining of the brake pad on the disk, P is equal to the hydraulic actuating pressure of the brake, and S is equal to the surface area of the hydraulic actuating piston of the brake. If P is 2·105 Pa, Ftg is μ×2·105×S.
For a hydraulic actuating piston with a diameter of 60 mm, where μ is 0.5, FS is advantageously less than or equal to 280 Newtons (N).
For a piston with a diameter of 36 mm, FS is advantageously less than or equal to 95 N, and preferably less than or equal to 40 N, and even more preferably less than or equal to 30 N. For a 36 mm piston, FS is for example 20N, 25 N, 30 N or 40 N.
Advantageously, this limited stiffness is due to the geometry of the laminar element, in particular the angle “β”, and a cutout 68 as described below.
The invention proposes a design of the laminar element 22 that is able to preload the pad spring 40 once it has been inserted in the laminar element 22, thereby enabling limited stiffness on the third flange 28.
The laminar element 22 is elastically deformable between an initial state as shown in
In this layout, in the initial state thereof, the upper sliding axial part 52 with a C-shaped section is substantially “closed”, the first sliding flange 24 also forming an acute angle with all planes parallel to the second upper vertical supporting flange 25.
Equally, the third transverse supporting flange 28 forms an acute angle “α” with the transverse weight-bearing surface 20 of the arm 14.
When the pad spring 40 is inserted into the laminar element 22, the first sliding flange 24 forms a reduced acute angle “β” with all planes parallel to the second upper vertical supporting flange 25. Equally, the third transverse supporting flange 28 forms an acute angle “β” with the transverse weight-bearing surface 20 of the arm 14.
The pad spring 40 is then preloaded by the first sliding flange 24, which guarantees a minimum loading and/or pre-stressing of the pad spring when the brake pad 12 is subject to a rotational torque resulting from friction of the brake pad on the brake disk.
Finally, in instances of extreme loading of the pad spring 40 by the brake pad 12, and in particular if the brake pad tends to move transversely/horizontally in the direction “T”, the force exerted tends to force the third transverse supporting flange 28 to bear flatly against the transverse weight-bearing surface 20 of the arm 14, thus guaranteeing a flat-on-flat contact able to better absorb the forces, at low braking pressure, on account of the angles mentioned above, and by a cutout 68 described below.
In the preferred embodiment of the invention, as shown in
Furthermore, the vertical face 20 and the flange 28 of the laminar element are arranged beneath the midpoint “O” of application of the braking forces of the brake pad on the disk.
This arrangement makes it possible to substantially determine the position the application of point of the reaction forces of the arms 14 on the brake pad 12, and therefore to determine the reaction torque that is exerted about the midpoint “O” of application of the braking forces of the brake pad 12 on the disk.
Thus, the total torque applied to the brake pad 12 resulting from the torque exerted by the disk on the brake pad 12 and the reaction torque exerted by the arms 14 on the brake pad 12 is always oriented in the same direction, which guarantees the stability of the brake pad 12 during braking.
As shown in
This cutout enables the angular stiffness of the edge 66 to be reduced, thereby facilitating the deployment or “opening” of the transverse supporting flange.
In this case, the axial cutout 68 extends symmetrically along the connection edge 66, covering most of the width, in the axial direction, of the connection edge 66.
As for the pad spring 40 described above, the first lower sliding flange 24 has an anchoring or attachment tab or tongue 56, in this case cut out from the first lower flange 24, that protrudes vertically downwards and that cooperates with the lower face 34 of the seat 16 to anchor itself in this lower face 34 of said seat 16.
The laminar element 22 also includes an axial immobilization part 58 that prolongs the second vertical supporting flange 25 upwards, and that cooperates with a matching part 60 of the arm 14 to axially immobilize the laminar element 22 in relation to the arm 14.
As shown in
A method for assembling a disk brake is related to the disk brake according to the invention.
This assembly method includes a first step in which the laminar elements 22 are positioned and locked in the related seats 16 of the arms 14 of the fork 11.
The method includes a second subsequent step in which the pad springs 40 are attached to the brake pad 12, the curved branches 48 being arranged on the same side of the brake pad 12.
The method then includes a third step in which the brake pad 12, previously fitted with the two pad springs 40 thereof, is inserted into the seats 16 of the arms 14 of the fork 11 by first inserting the curved branches 48 of the pad springs 40 so that these branches 48 of said pad springs 40 load the laminar elements 22 by separating the first lower sliding flanges 24 from the second vertical supporting flanges 25, thereby pre-stressing the pad springs 40.
Similarly, a method for replacing a brake pad 12 is related to the disk brake according to the invention.
Finally, during the final step, a new brake pad 12 with lugs 26 fitted with two pad springs 40 is inserted into the related seats 16 of the arms 14 of the caliper by inserting first the curved branches 48 of the pad springs 40 so that these branches 48 of the pad springs 40 load the laminar elements 22 by “vertically” separating the first lower sliding flanges 24 from the second vertical supporting flanges 25, thereby pre-stressing the pad springs 40.
The invention proposes a disk brake that suffers no untimely movement of the brake pads 12, which helps to stabilize said brake pads 12, increases the life of the friction linings of said brake pads 12 and reduces braking noise.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13 53906 | Apr 2013 | FR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20090159376 | Rossignol et al. | Jun 2009 | A1 |
| 20120222925 | Kaneko | Sep 2012 | A1 |
| 20140326548 | Merrien et al. | Nov 2014 | A1 |
| Number | Date | Country |
|---|---|---|
| 199 56 968 | May 2000 | DE |
| 2013087856 | Jun 2013 | WO |
| 2013087868 | Jun 2013 | WO |
| Entry |
|---|
| French Search Report, dated Apr. 9, 2014, from corresponding FR application. |
| Number | Date | Country | |
|---|---|---|---|
| 20140318905 A1 | Oct 2014 | US |
