"actuation device for a disc brake"

Abstract

An actuation device (1) for a disc brake (2), comprises a thrust plate (3), a ball ramp motion converter (5), having a first ramp portion (6) axially constrained and rotatable around the actuation axis (4), a second ramp portion (7) coupled with the thrust plate (3) and a plurality of rolling elements (8) interposed in contact between ramp tracks (9) formed by the first (6) and second ramp portion (7), a screw-nut motion converter (22) connected between the second ramp portion (6) and the thrust plate (3), a torque limiter (23) which establishes a torsional connection between the first ramp portion (6) and the second ramp portion (7), wherein the actuation device (1) comprises a joint (10) interposed between the second ramp portion (7) and the thrust plate (3), and wherein the joint (10) is configured to transfer the braking force between the second ramp portion (7) and the thrust plate (3), and to allow and accommodate rotational and / or translational displacements of the thrust plate (3) relative to the second ramp portion (7).

Description

“Actuation device for a disc brake”

[0001] Field of the invention

[0002] The present invention relates to an actuating device for a disc brake, in particular for an electromechanical disc brake, as well as to a disc brake provided with such an actuating device.

[0003] Prior art

[0004] Actuating devices for disc brakes of the Brake-By-Wire type (or “BBW”) are known, comprising a gearmotor associated with a ball screw motion converter formed by a threaded shaft and a nut screw, which converts the torque generated by the gearmotor into a braking force directed against the pads of the disc brake.

[0005] It is known to apply the torque generated by the gearmotor to the threaded shaft, so as to induce a translation of the nut screw towards the pads of the disc brake and thereby generate the braking force.

[0006] In these actuating devices, the ball screw performs two functions. The first is to transmit braking force to the pad of the disc brake, such that the pad applies a braking torque on the brake disc of the disc brake. The second function is to recover, i.e. compensate, for pad wear.

[0007] Although suitable for transferring braking load to the pads of the disc brake and compensating for wear thereof, the actuating devices with ball screw motion converters HAVE several drawbacks.

[0008] For example, these actuating devices have a large axial size, i.e. in the direction of the application of the braking force, as well as high costs, noise levels, and weight.

[0009] Another drawback of actuating devices with ball screw motion converters lies in the impossibility of defining non-linear advancement laws. Indeed, ball screws have a constant thread pitch and, consequently, a linear advancement law directly proportional to the angle of rotation of the screw.

[0010] It would instead be desirable to have an actuating device with a non-linear advancement more suited to the distinct steps of approach of the piston until piston-pad- disc contact is achieved, and of clamping of the piston to press the pads against the brake disc.

[0011] A further known actuating device is the so-called “ball-in-ramp” mechanism. A ball-in-ramp mechanism is likewise a mechanism for converting rotary motion into translational motion and comprises two facing components, rotatable relative to each other, and a plurality of balls interposed in contact between the facing components and housed inside rolling tracks (or ramps) formed in the two components. The rolling trackshave a helical development so that the relative rotation between the two facing components results in a wedge effect and their mutual axial displacement away from each other.

[0012] Ball-in-ramp mechanisms have significantly smaller axial dimensions compared to ball screws, are capable of generating very high braking forces in linear or non-linear dependence (depending on the configuration of the ramp tracks for the balls) on the relative rotation angle of the two facing components.

[0013] However, known ball-in-ramp mechanisms present the drawback of a very limited axial stroke, which makes it difficult to compensate for the wear of the disc brake pads.

[0014] WO2021229375A1 , of the same Applicant, discloses an actuating device for a disc brake comprising a ball-in-ramp mechanism inside. However, such an actuating device is particularly exposed to non-axial loads, i.e. radial to the actuation axis of the device, due to the contact between the pad and the brake disc or to the elastic deformation of the brake caliper. These non-axial loads impair the operation of the actuating device as they affect the threaded connection between the piston and the screw body, and also prevent the balls from rolling correctly in their respective rolling tracks.

[0015] Solution

[0016] The object of the present invention is therefore to provide an actuating device for a disc brake having features such as to overcome at least some of the drawbacks highlighted in the prior art.

[0017] A particular object of the present invention is to provide an actuating device for a disc brake having reduced axial dimensions, costs, and weight, with the same braking efficiency or with improved braking efficiency.

[0018] A further particular object of the present invention is to provide an actuating device for a disc brake that can be configured with non-linear advancement laws.

[0019] A further particular object of the present invention is to provide an actuating device for a disc brake that is less exposed, or more resistant, to non-axial loads.

[0020] These and other objects are achieved by means of an actuating device for a disc brake, in particular for a Brake-By-Wire type braking system, according to claim 1 .

[0021] The dependent claims refer to preferred and advantageous embodiments of the present invention.

[0022] Figures

[0023] In order to better understand the invention and appreciate its advantages, some exemplary and non-limiting embodiments thereof will be described below, withreference to the accompanying figures, in which:

[0024] - Figure 1 is a front perspective view of an actuating device for a disc brake, according to one embodiment of the invention;

[0025] - Figure 2 is a rear perspective view of the actuating device for a disc brake shown in Figure 1 ;

[0026] - Figure 3 is an exploded view of the actuating device for a disc brake shown in Figure 1 ;

[0027] - Figure 4 is an axial sectional view of an actuating device for a disc brake, according to one embodiment of the invention;

[0028] - Figure 5 is an axial sectional view of the actuating device for a disc brake shown in Figure 1 ;

[0029] - Figure 6 is an axial sectional view of a disc brake, according to one embodiment of the invention.

[0030] Description of some preferred embodiments

[0031] In the following description, the term “front” refers to the orientation of sides, faces, surfaces, etc. in the direction of advancement (braking) of the piston or thrust plate, the term “rear” refers to the orientation of sides, faces, surfaces, etc. in the direction of retraction of the piston or thrust plate, unless otherwise specified. The terms “radial”, “circumferential”, and “axial” are to be understood with reference to the actuation axis of the piston or thrust plate, unless otherwise specified.

[0032] With reference to the figures, an actuating device is generally denoted by the reference number 1 . The actuating device 1 is suitable for a disc brake 2.

[0033] The actuating device 1 comprises a thrust plate 3, slidingly supported along an actuation axis 4.

[0034] The actuating device 1 further comprises a ramp-mounted ball motion converter 5, having a first ramp portion 6 axially constrained and rotatable about the actuation axis 4, a second ramp portion 7 coupled with the thrust plate 3 and facing the first ramp portion 6, and a plurality of rolling members 8 interposed in contact between ramp tracks 9, or cam tracks, formed by the first ramp portion 6 and the second ramp portion 7, so that the rotation of the first ramp portion 6 with respect to the second ramp portion 7, about the actuation axis 4, results in a braking translation of the second ramp portion 7 together with the thrust plate 3 with respect to the first ramp portion 6, along the actuation axis 4.

[0035] The actuating device 1 further comprises a screw-nut screw motion converter 22, without ball recirculation, connected between the second ramp portion 6 and the thrust plate 3, so that a rotation of the second ramp portion 6 with respect to the thrustplate 3 about the actuation axis 4 results in a further compensating translation of the thrust plate 3 with respect to the second ramp portion 6, along the actuation axis 4.

[0036] Furthermore, the actuating device 1 comprises a torque limiter 23 (or, in other words, a torsional clutch), which:

[0037] - realizes a torsional connection between the first ramp portion 6 and the second ramp portion 7, for their unison rotation about the actuation axis 4, until a predetermined limit torsional moment in said torsional connection is reached,

[0038] - decouples the rotation of the first ramp portion 6 with respect to the second ramp portion 7 about the actuation axis 4 when the predetermined limit torsional moment is exceeded.

[0039] In this way, in a first step of approach of the thrust plate 3 to the pad 21 until a thrust plate-pad-brake disc engagement is achieved (the overstroke step required to compensate for the worn pad thickness), both the ramp portions 6, 7 of the rampmounted ball motion converter 5 rotate in unison and advance the thrust plate 3 due to the action of the screw-nut screw motion converter 22 alone. At the end of the first approach step, the pressing engagement of the thrust plate-pad-brake disc increases the mechanical resistance against further advancement of the thrust plate 3 until the predetermined limit torsional moment in the torsional connection between the first ramp portion 6 and the second ramp portion 7 is exceeded, and their relative rotation results in the braking translation of the thrust plate 3 (for a very limited braking stroke), due to the action of the ramp-mounted ball motion converter 5 alone.

[0040] The thrust plate 3 is operatively connected to the second ramp portion 7. Moreover, the thrust plate 3 is configured to receive a braking force from the second ramp portion 7 generated by the translation of the second ramp portion 7 induced by the rotation of the first ramp portion 6.

[0041] The thrust plate 3 is configured to discharge the braking force onto a pad 21 of the disc brake 2.

[0042] The actuating device 1 further comprises an joint 10 interposed between the second ramp portion 7 and the thrust plate 3.

[0043] The joint 10 is configured to:

[0044] - transfer the braking force between the second ramp portion 7 and the thrust plate 3, and

[0045] - allow and accommodate rotational and / or translational displacements of the thrust plate 3 with respect to the second ramp portion 7.

[0046] Advantageously, an actuating device 1 configured in this manner is more compact and lighter than the actuating devices of the prior art.

[0047] As a further advantage, the actuating device 1 so configured eliminates the need to use ball screw motion converters and features reduced dimensions, weight, and cost.

[0048] As a further advantage, the actuating device 1 so configured is less stressed by non-axial loads and forces, i.e. radial to the actuation axis 4. Indeed, when the actuating device 1 is actuated to apply a braking force, the joint 10 allows the thrust plate 3 to be in full contact with a pad 21 of the disc brake 2 even when the pad 21 of the disc brake 2 flexes under the force applied by the actuating device 1 , while at the same time preventing such loads from being transferred to the ramp-mounted ball motion converter 5. As a further advantage, the joint 10 avoids the generation of unbalanced loads acting on the ramp-mounted ball motion converter 5, which would otherwise be caused by deformation of the caliper of the disc brake 2 under the action of the braking force.

[0049] The first ramp portion 6 can be connected to an input shaft or to a generic rotating input member, for example of a reduction gear or an electric motor.

[0050] Conventionally, the thrust plate 3 is configured to transmit an axial force in the direction of the actuation axis 4, onto a pad 21 of the disc brake 2.

[0051] The actuating device 1 so configured converts a torque originating from the rotating input member into a linear force, through two distinct operating steps. In the first step, pad wear recovery of the pads 21 of the disc brake 2 takes place, by moving the thrust plate 3 close to the pad 21 of the disc brake 2. This movement is achieved by means of the screw-nut screw motion converter 22, through forces that are not high, and lower than the braking force. In the second step, the actual braking occurs, i.e. the generation of the braking force by the thrust plate 3 on the pad 21 of the disc brake 2. The translational movement of the thrust plate 3 that generates the braking force is produced by means of the ramp-mounted ball motion converter 5.

[0052] Joint 10

[0053] According to one embodiment, the joint 10 is a ball joint.

[0054] According to one embodiment, the joint 10 defines a convex surface 11 facing the thrust plate 3. The convex surface 1 1 is convex with respect to the thrust plate 3.

[0055] According to one embodiment, the thrust plate 3 comprises a front plate wall 12 and an opposite rear plate wall 13. Optionally, the front plate wall 12 and the rear plate wall 13 are coaxial with the actuation axis 4.

[0056] The front plate wall 12 defines a thrust surface 14, which can face, and is adapted to abut against, the pad 21 of the disc brake 2.

[0057] The thrust surface 14 extends on a plane orthogonal to the actuation axis 4. Preferably, the thrust surface 14 is coaxial with the actuation axis 4.

[0058] The rear plate wall 13 defines a concave surface 15 facing the joint 10. The concave surface 15 is concave with respect to the joint 10.

[0059] The convex surface 11 of the joint 10 is positioned abutting against the concave surface 15 of the thrust plate 3.

[0060] The convex surface 11 of the joint 10 and the concave surface 15 of the thrust plate 3 form a shape coupling.

[0061] Advantageously, this shape coupling between the joint 10 and the thrust plate 3 allows for a relative rotation between the thrust plate 3 and the joint 10 about the actuation axis 4 and / or about rotation axes orthogonal to the actuation axis 4, which prevents or minimizes the transfer of radial loads to the ramp-mounted ball motion converter 5.

[0062] According to one embodiment, the concave surface 15 or the convex surface 11 , preferably both the concave surface 15 and the convex surface 11 , are shaped as a portion of a sphere.

[0063] According to one embodiment, the joint 10 comprises a centering pin 16 projecting from the convex surface 11 , along the actuation axis 4.

[0064] Furthermore, the rear plate wall 13 of the thrust plate 3 defines a corresponding pin seat 17, extending inside the rear plate wall 13 and / or the concave surface 15, along the actuation axis 4.

[0065] The centering pin 16 of the joint 10 is inserted into the pin seat 17 of the thrust plate 3.

[0066] Advantageously, this configuration preserves the connection between the thrust plate 3 and the joint 10, limiting the maximum relative rotation between the thrust plate 3 and the joint 10.

[0067] Screw-nut screw motion converter 22

[0068] The screw-nut screw motion converter 22 comprises a screw body 29 and a nut screw body 30 externally screwed to the screw body 29.

[0069] Both the screw body 29 and the nut screw body 30 extend in the direction of the actuation axis 4, preferably coaxial to the actuation axis 4.

[0070] According to one embodiment, the second ramp portion 7 may be directly formed at the nut screw body 30 of the screw-nut screw motion converter 22.

[0071] This increases the compactness of the actuating device 1 , reducing its axial dimensions along the actuation axis 4.

[0072] According to one embodiment, the nut screw body 30 forms an internally threaded wall 33, substantially cylindrical and concentric with respect to the actuationaxis 4.

[0073] According to one embodiment, the screw body 29 forms:

[0074] - an externally threaded side wall 34, substantially cylindrical and concentric with respect to the actuation axis 4, for screwing with the internally threaded wall 33 of the nut screw body 30;

[0075] - a front screw wall 35 facing in the advancement direction of the thrust plate3 and a rear screw wall 36 opposite to the front screw wall 35;

[0076] - a geometric coupling hole 37, extending through the rear screw wall 36 into the screw body 29 in the direction of the actuation axis 4, for accommodating an antirotation pin 38.

[0077] Optionally, the geometric coupling hole 37 defines, in a section orthogonal to the actuation axis 4, a prismatic shape configured to prevent a relative rotation between the geometric coupling hole 37 and the anti-rotation pin 38 about the actuation axis 4.

[0078] Advantageously, this configuration contributes to a further reduction of the axial dimensions of the actuating device 1 .

[0079] The geometric coupling hole 37 opens onto the rear screw wall 36. In particular, the anti-rotation pin 38 is inserted into the geometric coupling hole 37 through the rear screw wall 36, so as to realise the geometric coupling with the geometric coupling hole 37.

[0080] According to one embodiment, the geometric coupling hole 37 is a through hole passing through the screw body 29, coaxial with the actuation axis 4. Consequently, the geometric coupling hole 37 extends between the front screw wall 35 and the rear screw wall 36.

[0081] According to one embodiment, the anti-rotation pin 38 is connected, preferably directly and in contact, to a force sensor 39. The force sensor 39 is configured to detect the braking force applied by the actuating device 1 .

[0082] The force sensor 39 is positioned opposite to the screw-nut screw motion converter 22, with respect to the anti-rotation pin 38. According to this embodiment, the anti-rotation pin 38 is configured to discharge onto the force sensor 39 the reaction force acting on the thrust plate 3.

[0083] Advantageously, by detecting the force acting on the anti-rotation pin 38, originating from the thrust plate 3, the force sensor 39 is able to determine the braking force applied by means of the actuating device 1 .

[0084] According to one embodiment, the screw body 29 defines a joint seat 18, for housing the joint 10. In particular, the joint seat 18 is defined at the front screw wall 35.

[0085] The joint seat 18 extends into the screw body 29, along the actuation axis 4.

[0086] The joint seat 18 is defined by a peripheral surface 19 and a bottom surface 20.

[0087] The peripheral surface 19 faces the actuation axis 4. Optionally, the peripheral surface 19 is coaxial with the actuation axis 4 and has a substantially cylindrical shape.

[0088] The joint 10 is positioned abutting against the bottom surface 20. The bottom surface 20 extends substantially along a plane orthogonal to the actuation axis 4.

[0089] The joint 10 is at least partially inserted into the joint seat 18, optionally entirely inserted into the joint seat 18.

[0090] Furthermore, the thrust plate 3 is at least partially inserted into the joint seat 18. Optionally, the rear plate wall 13 is entirely inserted into the joint seat 18. Optionally, the concave surface 15 is entirely positioned within the joint seat 18.

[0091] Advantageously, this configuration further reduces the axial dimensions of the actuating device 1 , since the axial dimensions of the second ramp portion 7, the joint 10, and the thrust plate 3 are at least partially overlapped.

[0092] “Axial dimension” is intended to mean the projection or footprint of a component along the actuation axis 4.

[0093] According to one embodiment, the actuating device 1 comprises a damper element 48 interposed between the thrust plate 3 and the second ramp portion 7.

[0094] The damper element 48 is configured to dampen the relative movement between the thrust plate 3 and the second ramp portion 7.

[0095] Furthermore, the damper element 48 is configured to axially constrain the thrust plate 3 to the second ramp portion 7.

[0096] Advantageously, the damper element 48 reduces the transmission of radial loads from the thrust plate 3 to the second ramp portion 7. As a further advantage, the damper element 48 retains the thrust plate 3 to the second ramp portion 7 such that, during release of the braking force, i.e. during retraction of the actuating device 1 , the thrust plate 3 is also retracted towards the rest position.

[0097] According to one embodiment, the damper element 48 is made of a polymer material.

[0098] According to one embodiment, the damper element 48 is an annular gasket. Optionally, such annular gasket is fitted onto the thrust plate 3, in particular on the rear plate wall 13, and interposed between the thrust plate 3, in particular the rear plate wall 13, and the peripheral surface 19 of the joint seat 18.

[0099] According to one embodiment, the damper element 48 is positioned interposed between the thrust plate 3 and the screw body 29. Consequently, the damper element 48 is configured to dampen a relative movement between the thrust plate 3 andthe screw body 29, and to axially constrain the thrust plate 3 to the screw body 29.

[0100] Ramp-mounted ball motion converter 5

[0101] According to one embodiment, the first ramp portion 6 may itself form the rotating input member.

[0102] This increases the compactness of the actuating device 1 , reducing its axial dimensions along the actuation axis 4.

[0103] According to one embodiment, the first ramp portion 6 is formed by a rotor body 24 having a substantially cylindrical shape, with a circumferential rotor wall 25 extending in a direction opposite to the actuation axis 4, a front rotor wall 26, and a rear rotor wall 27.

[0104] The front rotor wall 26 faces in an advancement direction of the thrust plate 3 and forms one or more, preferably three, first rolling tracks 28 of the ramp tracks 9.

[0105] The circumferential rotor wall 25 may form a toothing 47, preferably an external toothing, extending around the actuation axis 4, for example at the front rotor wall 26, for transmitting an actuation torque / rotation.

[0106] According to one embodiment, a rear nut screw wall 31 of the nut screw body 30, facing the rotor body 24, forms at least one, preferably three, second rolling tracks 32 of the ramp tracks 9.

[0107] Advantageously, respectively one first rolling track 28 and one second rolling track 32, facing each other, respectively accommodate a rolling member 8, in particular a rolling ball 8.

[0108] The ramp tracks 9 of the ramp portions 6, 7 extend helically (or, in other words: eccentrically and in a circumferential direction) with respect to the actuation axis 4. Each of the ramp portions 6, 7 may form, for example, two or three ramp tracks 9 arranged in circumferential succession and separated from each other, for example by separating ribs, so as to accommodate the rolling members (the rolling balls 8) in their planned position.

[0109] The ramp tracks 9 may be configured as a variable pitch helix in the direction of the actuation axis 4, defining a non-linear rotation-to-translation conversion law.

[0110] According to one embodiment, at least one ramp track 9 is shaped so as to radially limit the movement of the rolling member 8, in particular the rolling ball 8.

[0111] Advantageously, this avoids the risk of possible ejection of at least one rolling member 8, in particular a rolling ball 8, from the corresponding ramp track 9.

[0112] According to an advantageous embodiment, the rolling members 8 are also accommodated in a retaining cage interposed between the first ramp portion 6 and the second ramp portion 7, i.e., between the rotor body 24 and the nut screw body 30.

[0113] According to one embodiment, the first ramp portion 6, the second ramp portion 7, and the rolling members 8 are elastically biased into contact with each other in the direction of the actuation axis 4. This prevents the onset of vibrations and noise from the balls in the ramp tracks and maintains the individual components in their planned position.

[0114] According to one embodiment, the rotor body 24 defines a through hole 41 extending inside the rotor body 24 coaxially to the actuation axis 4.

[0115] The nut screw body 30 is at least partially inserted through the through hole 41 , so that the internally threaded wall 33 of the nut screw body 30 is at least partially housed inside the through hole 41 .

[0116] Advantageously, this configuration further reduces the axial dimensions of the actuating device 1 .

[0117] Torque limiter 23

[0118] According to one embodiment, the torque limiter 23 is at least partially, preferably entirely, housed in an internal cavity of the rotor body 24, preferably formed at the rear rotor wall 27.

[0119] According to one embodiment, the torque limiter 23 is formed by a torsional spring 40, for example a spiral spring, connected between the first ramp portion 6 and the second ramp portion 7 of the ramp-mounted ball motion converter 5.

[0120] The torque-deformation curve of the torsional spring 40 is selected so that, below the predetermined limit torsional moment, the torsional spring 40 substantially rotationally couples the first ramp portion 6 and the second ramp portion 7, whereas above the predetermined limit torsional moment, the torsional spring 40 progressively deforms, allowing a relative rotation of the first ramp portion 6 with respect to the second ramp portion 7.

[0121] According to one embodiment, a first end of the torsional spring 40 is integrally connected to the rotor body 24, and a second end of the torsional spring 40 is integrally connected to the nut screw body 30.

[0122] Additional components of the actuating device 1

[0123] According to one embodiment, the actuating device 1 comprises a radial bearing 41 .

[0124] The radial bearing 41 is fitted onto the rotor body 24. Specifically, the radial bearing 41 is interposed between the rotor body 24 and a wall of the housing of the disc brake 2, so as to allow a relative rotation of the rotor body 24 with respect to said wall of the housing of the disc brake 2.

[0125] Optionally, the radial bearing 41 is a roller-type bearing. Alternatively, theradial bearing 41 is a ball bearing.

[0126] According to one embodiment, the actuating device 1 comprises a thrust bearing 42.

[0127] The thrust bearing 42 realizes a reaction support for the rotor body 24 in the direction of the actuation axis 4.

[0128] The thrust bearing 42 is positioned at the rear rotor wall 27.

[0129] According to one embodiment, the thrust bearing 42 comprises a first ring 43 and an opposite second ring 44. The first ring 43 is rotatable with respect to the second ring 44 about the actuation axis 4.

[0130] According to one embodiment, the first ring 43 is distinct from the rotor body 24, is positioned abutting against the rear rotor wall 27, and is integrally connected to the rotor body 24.

[0131] Alternatively, the first ring 43 is formed in one piece with the rotor body 24, in particular with the rear rotor wall 27.

[0132] According to one embodiment, the screw body 29 is positioned passing through the thrust bearing 42.

[0133] Advantageously, this configuration further reduces the overall dimensions of the actuating device 1 .

[0134] According to one embodiment, the thrust bearing 42 is positioned interposed between the rear rotor wall 27 and the anti-rotation pin 38.

[0135] According to one embodiment, the actuating device 1 comprises a spacer 45. The spacer 45 is positioned interposed between the second ring 44 of the thrust bearing 42 and the anti-rotation pin 38. The spacer 45 has a substantially annular shape, coaxial to the actuation axis 4.

[0136] According to one embodiment, the actuating device 1 comprises a static gasket 46 connected to the thrust plate 3 and extending radially outward from the thrust plate 3.

[0137] The static gasket 46 is configured to create a fluid-tight seal between the pad 21 of the disc brake 2 and the components of the actuating device 1 positioned opposite the thrust plate 3 with respect to the pad 21 .

[0138] In particular, the static gasket 46 is positioned at the thrust plate 3, so as to separate both the ramp-mounted ball motion converter 5 and the screw-nut screw motion converter 22 from the pad 21 .

[0139] According to one embodiment, the static gasket 46 is a bellows-type gasket.

[0140] Advantageously, the static gasket 46 protects said mechanical components ofthe actuating device 1 , in particular the ramp-mounted ball motion converter 5 and the screw-nut screw motion converter 22, from contact with dust, moisture or other contaminants.

[0141] Disc brake 2

[0142] A disc brake 2 conventionally comprises a caliper, comprising two side walls spaced apart from each other which delimit a disc space for accommodating a portion of a brake disc, means for fixing the caliper to a vehicle, a connection structure extending across the disc space and connecting the side walls to each other, at least one pad seat formed in each of said side walls and adapted to accommodate at least one friction pad 21 , thrust means constrained to one or both side walls and adapted to bias the friction pads 21 against the brake disc to clamp it, wherein, according to the present invention, the thrust means comprise the actuating device 1 as described above.

[0143] According to one embodiment, the caliper is of the floating type. According to an alternative embodiment, the caliper is of the fixed type.

[0144] According to one embodiment, the disc brake 2 comprises a gearmotor and a transmission system configured to transmit a mechanical power generated by the gearmotor to the rotor body 24 of the actuating device 1 , in particular to the toothing 47. In particular, the transmission system comprises a gear meshing with the toothing 47 of the rotor body 24.

[0145] Advantageously, an actuating device 1 and a disc brake 2 so configured are integrable both in motorcycles or motor vehicles with at least two wheels, for both front and rear brakes, and in motor vehicles and heavy vehicles such as vans and trucks.

[0146] Naturally, the person skilled in the art will be able to make changes or adaptations to the present invention, without however departing from the scope of the following claims.Reference list1 . Actuating device2. Disc brake3. Thrust plate4. Actuation axis5. Ramp-mounted ball motion converter6. First ramp portion7. Second ramp portion8. Rolling member9. Ramp track10. Joint11 . Convex surface12. Front plate wall13. Rear plate wall14. Thrust surface15. Concave surface16. Centering pin17. Pin seat18. Joint seat19. Peripheral surface20. Bottom surface21 . Pad22. Screw-nut screw motion converter23. Torque limiter24. Rotor body25. Circumferential rotor wall26. Front rotor wall27. Rear rotor wall28. First rolling track29. Screw body30. Nut screw body31 . Rear nut screw wall32. Second rolling track33. Internally threaded wall34. Externally threaded wall35. Front screw wall

Claims

Claims1. An actuating device (1 ) for a brake disc (2), comprising:- a thrust portion (3) slidingly supported along an actuation axis (4);- a first ramp-mounted ball motion converter (5), having a first ramp portion (6) axially constrained and rotationally actuatable about the actuation axis (4), a second ramp portion (7) coupled to the thrust plate (3) and facing the first ramp portion (6), and a plurality of rolling members (8) interposed in contact between the ramp tracks (9) formed by the first (6) and second (7) ramp portions, so that the rotation of the first ramp portion (6) with respect to the second ramp portion (7), about the actuation axis (4), results in a braking translation of the second ramp portion (7) together with the thrust plate (3) with respect to the first ramp portion (6), along the actuation axis (4),- a screw-nut screw motion converter (22), without ball recirculation, connected between the second ramp portion (6) and the thrust plate (3), so that a rotation of the second ramp portion (6) with respect to the thrust plate (3) about the actuation axis (4) results in a compensating translation of the thrust plate (3) with respect to the second ramp portion (6), along the actuation axis (4),- a torque limiter (23) that:- realizes a torsional connection between the first ramp portion (6) and the second ramp portion (7), for a unison rotation thereof about the actuation axis (4) until a predetermined limit torsional moment in said torsional connection is achieved,- decouples the rotation of the first ramp portion (6) with respect to the second ramp portion (7) about the actuation axis (4) when the predetermined limit torsional moment is exceeded, wherein the thrust plate (3) is operatively connected to the second ramp portion (7), and is configured to receive a braking force from the second ramp portion (7) generated by the translation of the second ramp portion (7) induced by the rotation of the first ramp portion (6), wherein the thrust plate (3) is configured to discharge the braking force onto a pad (21 ) of the disc brake (2), wherein the actuating device (1 ) comprises a joint (10) interposed between the second ramp portion (7) and the thrust plate (3), and wherein the joint (10) is configured to:- transfer the braking force between the second ramp portion (7) and the thrust plate (3), and- allow and accommodate rotational and / or translational displacements of the thrust plate (3) with respect to the second ramp portion (7).

2. An actuating device (1 ) according to claim 1 , wherein the joint (10) is a ball joint.

3. An actuating device (1 ) according to claim 1 or 2, wherein the joint (10) defines a convex surface (11 ) facing the thrust plate (3), wherein the thrust plate (3) comprises a front plate wall (12) and an opposite rear plate wall (13), wherein the front plate wall (12) defines a thrust surface (14), which can face, and adapted to abut against, the pad (21 ) of the disc brake (2), wherein the rear plate wall (13) defines a concave surface (15) facing the joint (10), wherein the convex surface (11 ) of the joint (10) is positioned abutting against the concave surface (15) of the thrust plate (3), so that the convex surface (11 ) of the joint (10) and the concave surface (15) of the thrust plate (3) form a shape coupling, and wherein, optionally, the concave surface (15) and / or the convex surface (1 1 ) are in the shape of a ball portion, and wherein, optionally, the joint (10) comprises a centering pin (16) extending projecting from the convex surface (1 1 ), wherein the rear plate wall (13) of the thrust plate (3) defines a corresponding pin seat (17), and wherein the centering pin (16) of the joint (10) is inserted into the pin seat (17) of the thrust plate (3).

4. An actuating device (1 ) according to any one of the preceding claims, wherein the screw-nut screw motion converter (22) comprises a screw body (29) and a nut screw body (30) externally screwed to the screw body (29), wherein the second ramp portion (7) is directly formed at the nut screw body (30) of the screw-nut screw motion converter (22).

5. An actuating device (1 ) according to any one of the preceding claims, wherein the screw-nut screw motion converter (22) comprises a screw body (29) and a nut screw body (30) externally screwed to the screw body (29), wherein the nut screw body (30) forms an internally threaded wall (33), wherein the screw body (29) forms:- an externally threaded side wall (34), for screwing with the internally threaded wall (33) of the nut screw body (30);- a front screw wall (35) facing in the advancement direction of the thrust plate (3) and a rear screw wall (36) opposite to the front screw wall (35);- a geometric coupling hole (37), extending through the rear screw wall (36) into thescrew body (29) in the direction of the actuation axis (4), for accommodating an antirotation pin (38), and wherein, optionally, the geometric coupling hole (37) defines, in a section orthogonal to the actuation axis (4), a prismatic shape configured to prevent a relative rotation between the geometric coupling hole (37) and the anti-rotation pin (38) about the actuation axis (4).

6. An actuating device (1 ) according to claim 5, wherein the anti-rotation pin (38) is connected to a force sensor (39) configured to detect the braking force applied by the actuating device (1 ).

7. An actuating device (1 ) according to any one of the preceding claims, wherein the screw-nut screw motion converter (22) comprises a screw body (29) and a nut screw body (30) externally screwed to the screw body (29), wherein the screw body (29) defines a joint seat (18), for housing the joint (10), wherein the joint seat (18) extends into the screw body (29), along the actuation axis (4), wherein the joint seat (18) is defined by a peripheral surface (19) and a bottom surface (20), wherein the peripheral surface (19) faces the actuation axis (4), wherein the joint (10) is positioned abutting against the bottom surface (20), and wherein, optionally, the joint (10) is entirely inserted into the joint seat (18).

8. An actuating device (1 ) according to any one of the preceding claims, comprising a damper element (48) interposed between the thrust plate (3) and the second ramp portion (7), wherein the damper element (48) is configured to dampen the relative movement between the thrust plate (3) and the second ramp portion (7), wherein the damper element (48) is an annular gasket, made of a polymer material, fitted onto the thrust plate (3) and interposed between the thrust plate (3) and a peripheral surface (19) of a joint seat (18).

9. An actuating device (1 ) according to any one of the preceding claims, wherein the first ramp portion (6) is formed by a rotor body (24) being substantially cylindrical in shape, with a circumferential rotor wall (25) extending in the direction opposite to the actuation axis (4), a front rotor wall (26), and a rear rotor wall (27), wherein the front rotor wall (26) faces an advancement direction of the thrust plate (3) and forms one or more, optionally three, first rolling tracks (28) of the ramp tracks (9),wherein the circumferential rotor wall (25) forms a toothing (47), optionally an external toothing, extending about the actuation axis (4), for transmitting an actuation torque / rotation, wherein a rear nut screw wall (31 ) of a nut screw body (30), facing the rotor body (24), forms at least one, optionally three, second rolling tracks (32) of the ramp tracks (9), and wherein a first rolling track (28) and a second rolling track (32), facing each other, respectively, accommodate a rolling member (8) therebetween, respectively.

10. An actuating device (1 ) according to claim 9, wherein the rotor body (24) defines a through hole (41 ) extending into the rotor body (24) coaxially to the actuation axis (4), and wherein the nut screw body (30) is at least partially inserted through the through hole(41 ), so that an internally threaded wall (33) of the nut screw body (30) is at least partially accommodated inside the through hole (41 ).

11. An actuating device (1 ) according to claim 9 or 10, wherein the torque limiter (23) is at least partially, optionally entirely, accommodated in an internal cavity of the rotor body (24) formed at the rear rotor wall (27), and / or wherein the torque limiter (23) is formed by a torsional spring (40) connected between the first ramp portion (6) and the second ramp portion (7) of the ramp-mounted ball motion converter (5), wherein a first end of the torsional spring (40) is integrally connected to the rotor body (24), and a second end of the torsional spring (40) is integrally connected to a nut screw body (30).

12. An actuating device (1 ) according to any one of the preceding claims, comprising:- a radial bearing (41 ), fitted onto a rotor body (24), optionally interposed between the rotor body (24) and a wall of the housing of the disc brake (2), so as to allow a relative rotation of the rotor body (24) with respect to said housing wall of the disc brake (2), and / or- a thrust bearing (42), which realizes a reaction support for a rotor body (24) in the direction of the actuation axis (4), wherein the thrust bearing (42) is positioned at a rear rotor wall (27), wherein the thrust bearing (42) comprises a first ring (43) and an opposite second ring (44), wherein the first ring (43) is rotatable with respect to the second ring (44), about the actuation axis (4), and wherein the first ring (43) is distinct from the rotor body (24) or is formed in one piece with the rotor body (24), wherein, optionally, the screw body (29) is positioned to pass through the thrust bearingwherein, optionally, the thrust bearing (42) is positioned interposed between the rear rotor wall (27) and the anti-rotation pin (38), and / or- a spacer (45), positioned interposed between a second ring (44) of a thrust bearing (42) and an anti-rotation pin (38), wherein the spacer (45) is substantially annular in shape, coaxially to the actuation axis (4), and / or- a static gasket (46) connected to the thrust plate (3) and extending radially outwards from the thrust plate (3), wherein the static gasket (46) is positioned at the thrust plate (3), so as to separate both the ramp-mounted ball motion converter (5) and the screw- nut screw motion converter (22) from the pad (21 ), wherein, optionally, the static gasket (46) is a “bellows” type gasket.

13. An actuating device (1 ) according to any one of the preceding claims, to be integrated in motorcars or motorcycles with at least two wheels, for both the front and rear brakes, and in motor vehicles and heavy vehicles.

14. A disc brake (2) comprising a caliper, of the floating or fixed type, with two side walls spaced apart from each other which delimit a disc space for accommodating a portion of a brake disc, means for fixing the caliper to a vehicle, a connection structure which extends straddling the disc space and connects the side walls to each other, at least one pad seat formed in each of said side walls and adapted to accommodate at least one friction pad (21 ), thrust means constrained to one or both side walls and adapted to bias the friction pads (21 ) against the brake disc to clamp it, and wherein the thrust means comprise an actuating device (1 ) according to any one of the preceding claims, and wherein, optionally, the disc brake (2) comprises a gearmotor and a transmission system configured to transmit a mechanical power generated by the gearmotor to a rotor body (24) of the actuating device (1 ), optionally to a toothing (47) of the rotor body (24), and wherein the disc brake (2) can be integrated in motorcars or motorcycles with at least two wheels, for both the front and rear brakes, and in motor vehicles and heavy vehicles.

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