Spiral connection mechanism for simplified mounting of electromechanical brake caliper pistons

Abstract

The present invention relates to a screw connection mechanism for an electromechanical brake piston, configured to be mounted inside the piston, comprising a sleeve (13) and a drive member (9) cooperating by means of a screw connection having a longitudinal axis (AX), and means (14) for rotationally locking the sleeve with respect to the piston about the longitudinal axis (AX) and axially retaining the mechanism, said means comprising a plate (28) fixed to the sleeve (13) and extending orthogonally to the longitudinal axis (AX), at least three axial extensions (32) cooperating with an axial wall of the piston, and at least one radial shape (40) cooperating with an axial wall of the piston.

Description

TECHNICAL FIELD

[0001] The present invention relates to a screw connection mechanism for a piston of a caliper of a disc brake with an electromechanical actuator. BACKGROUND

[0002] An electromechanical disc brake comprises a caliper straddling a brake disc, such a caliper comprising a caliper body carrying two pads on either side of the disc and equipped with an electromechanical actuator for pressing the pads against the disc when activated, in order to generate a braking torque.

[0003] The caliper body has a cylindrical housing extending between the actuator and one of the pads, in which a movable piston having a head bearing on this pad slides. The actuator has an output shaft coupled to a drive or drive member, which forms part of a screw-type connection located in the cylindrical housing and partly in the piston, interposed between the actuator and the piston head.

[0004] When the actuator is activated, it exerts a torque via its output shaft, which is translated into pressure by the screw connection mechanism, so that the piston presses the pad onto the disc. The caliper is generally mounted to float in the axial direction of the disc, so that the pressure exerted by the single piston is sufficient to press the two opposite pads against the disc.

[0005] In such a system, the screw connection is irreversible: a force exerted on the piston does not induce the torque exerted by the drive to screw. This connection comprises a sleeve into which the drive member is screwed, which is housed in the piston and joined to the piston by a prismatic type of connection, i.e. which allows the sleeve to slide longitudinally in the piston but prevents it from rotating relative to the piston. The piston slides in its housing but is rotationally locked relative to the caliper body.

[0006] The prismatic connection is made by fixing a plate to the sleeve and extending it transversely to the axis of the sleeve, and by making the plate have notches on its outer periphery which cooperate with longitudinal ribs formed on the inner surface of the piston.

[0007] When the actuator is activated, which roughly corresponds to the parking brake command, the sleeve bearing against the inner face of the piston head pushes the piston towards the disc. Independently, pressurizing the piston housing, which roughly corresponds to the service brake command, also allows this piston to be pressed towards the disc.

[0008] However, during assembly of the brake, in particular during installation of the screw connection mechanism, the screw connection mechanism can be skewed relative to the longitudinal axis, which complicates further assembly, in particular the connection between the drive member and the electric motor. SUMMARY

[0009] It is therefore an object of the present application to provide a screw connection mechanism for a caliper piston of an electromechanical disc brake that facilitates the assembly of the brake.

[0010] The above object is achieved by a screw connection mechanism for a caliper piston of an electromechanical disc brake, comprising a sleeve and a drive member cooperating with each other by a screw connection, and means for rotationally stopping the sleeve in the piston, said stopping means also ensuring the holding of the sleeve and the drive member in a position coaxial to the piston.

[0011] In one illustrative embodiment, the rotational stopping and axial holding means comprise a plate attached to the sleeve, and axial extensions whose shape is set to cooperate with the internal surface of the piston and ensure the rotational locking of the sleeve with respect to the piston and the alignment of the sleeve with the piston axis.

[0012] In another illustrative embodiment, the rotational stopping and axial holding means comprise a plate attached to the sleeve, axial extensions whose shape is set to cooperate with the internal surface of the piston and ensure the alignment of the sleeve with the piston axis, and at least one shape cooperating with the internal surface of the piston and ensuring the rotational locking of the sleeve with respect to the piston, and

[0013] Very advantageously, the means are made by cutting, bending and stamping a sheet metal. The manufacturing is very simple. Moreover, the mass of the plate and extension assembly is low.

[0014] In other words, the anti-rotation function is supplemented by an anti-inclination function. The cost associated with this additional function is very low, or even zero.

[0015] The object of the present application is then a screw connection mechanism for a piston of an electromechanical brake, configured to be mounted in said piston, comprising a sleeve and a drive member cooperating with each other by a screw connection having a longitudinal axis, and means for rotationally locking said sleeve with respect to the piston around the longitudinal axis and axially holding the mechanism, said means comprising a plate attached to the sleeve and extending orthogonally to the longitudinal axis. The rotational locking and axial holding means comprise at least three axial extensions cooperating with an axial wall of the piston, and at least one radial shape cooperating with the axial wall of the piston.

[0016] In one illustrative embodiment, the at least one radial shape is carried by the axial extensions.

[0017] The at least one radial shape can be a groove or a rib extending axially along the axial extensions.

[0018] In another illustrative embodiment, the at least one radial shape is a protrusion or a recess in the outer edge of the plate.

[0019] In an advantageous example, the device is made by cutting and bending a sheet of metal.

[0020] It is also an object of the application a caliper for an electromechanical brake, comprising a caliper body comprising a housing enclosing a piston and a screw connection mechanism, said piston comprising an inner housing delimited by a bottom and a lateral wall and a mechanism according to the application, said lateral wall comprising in its inner surface at least one shape cooperating with a radial shape, said shape extending axially over the entire axial dimension of the inner surface of the lateral wall.

[0021] It is also an object of the application a disc brake comprising a caliper according to the application and an electric motor connected to a drive member.

[0022] It is also an object of the application a method for manufacturing a screw connection mechanism according to the application, the method comprising:

[0023] a) providing a sleeve and a drive member and assembling the sleeve and the drive member,

[0024] b) cutting a sheet of metal into a shape comprising a plate and elongated portions,

[0025] c) deforming said elongated portions so as to form axial extensions and optionally at least one radial shape,

[0026] d) attaching said shape to said sleeve.

[0027] In an example, said shape comprises at least one radial shape and elongated portions tangential to the plate. For example, step c) can comprise bending so as to fold these elongated portions around an axis extending radially with respect to the longitudinal axis.

[0028] In another example, said shape comprises radially extending elongated portions. For example, step c) comprises bending so as to fold these elongated portions around an axis tangential to the circle circumscribed by the plate, and stamping at least one elongated portion so as to form at least one radial shape. BRIEF DESCRIPTION OF DRAWINGS

[0029] The application will be better understood with the following description and the appended drawings, in which:

[0030] Figure 1 is a schematic cross-sectional view of an electromechanical disc brake.

[0031] Figure 2 is a perspective view of a screw connection mechanism according to a schematic embodiment.

[0032] Figure 3 isFigure 2 A partial longitudinal sectional view of the mechanism installed in the disc brake piston.

[0033] Figure 4 is a perspective view of a screw connection mechanism according to another exemplary embodiment.

[0034] Figure 5 is a perspective view of a screw connection mechanism according to another exemplary embodiment. DETAILED DESCRIPTION

[0035] exist Figure 1 In the figure, an electromechanical disc brake, indicated at 1 , can be seen comprising a caliper 2 comprising a caliper body 3 carrying two pads 4 and 5 which clamp a disc 6 , said caliper body 3 being equipped with an electromechanical actuator (not shown).

[0036] The caliper body comprises a cylindrical housing 7 extending between the actuator and one of the pads, in which a movable piston 8 is housed, the head of which is supported on the pad 4, this piston 8 being movable in translation relative to the caliper body 3 in the axial direction AX and locked in rotation about the axis AX.

[0037] This piston 8 is moved towards or pressed against the liner 4 by means of a screw connection 9 , which is coupled to an actuator (not shown) and is primarily housed in the piston 8 .

[0038] This screw connection 9 comprises a driver or drive member 11 screwed into a sleeve 13, carrying means 14 for locking the sleeve 13 in rotation relative to the piston 8 and keeping the mechanism aligned with the axis AX of the piston. Figure 1 As can be seen in FIG, the sleeve 13 and the device 14 are located in the internal space delimited by the cylindrical skirt 16 of the piston 8.

[0039] More specifically, the drive member 11 comprises a threaded body 17 having a free end 18 and a coupling end 19 for coupling to an actuator (not shown), and a head 21 located adjacent the coupling end 19 .

[0040] The head 21 is shaped substantially as a circular plate of considerable thickness, the outer diameter of which is smaller than the inner diameter of the skirt 16. This head 21 has a bearing surface 23 oriented toward the coupling end 19 and by means of which it bears against the flat bottom 22 of the cylindrical housing 7 via a bearing washer 24.

[0041] like Figure 1As can be seen in the figure, the coupling end 19 passes sealingly through a wall 26 defining the bottom 22 of the caliper body 3 via a hole 27 formed in this wall 26, allowing the output shaft of an actuator (not shown) to be coupled to this end 19, and thus protrudes from the caliper body 3. For example, the end 19 has a hexagonal hollow cavity into which one end of the output shaft of the actuator (which is fitted to the caliper body 3 on the outer face of the wall 26) engages. This type of connection is not restrictive.

[0042] In response to a parking brake command, rotation of the drive member 11 in the tightening direction allows the sleeve 13 to move away from the head 21, thereby causing the sleeve to press the piston 8 against the pad 4 to generate a braking torque. Conversely, rotation in the release direction in response to a parking brake release command moves the sleeve 13 toward the head 21, thereby reducing and canceling the braking torque.

[0043] Furthermore, the housing 7 and the mechanism 9 are immersed in a liquid. In response to a command to apply the service brakes, the pressure of this liquid increases, thereby pressing the piston against the pad 4 to generate a braking torque. Conversely, a decrease in pressure in response to a command to release the service brakes causes the pressure exerted by the piston on the pad 4 to decrease, thereby reducing or even canceling the braking torque.

[0044] exist Figure 2 In FIG. 1 , a schematic embodiment of the device 14 can be seen.

[0045] The device 14 comprises a plate 28 including a central orifice 30 mounted around the sleeve 13 and axial extensions 32 extending from the radially outer periphery of the plate towards the head 21. The plate is made rotationally immovable relative to the sleeve, for example by crimping. Advantageously, the sleeve has axial grooves to improve the rotational grip.

[0046] In the example illustrated, the sleeve 13 comprises a head 34 and a body 36 which is internally threaded and into which the threaded drive member enters.

[0047] The axial extension comprises axial grooves 40 which are intended to engage with axial ribs 42 ( Figure 3 ) and, by cooperating, improve the grip of the plate, and therefore the sleeve, relative to the piston. Alternatively, the axial extensions 40 may comprise ribs, and the skirt may comprise grooves. The outer diameter of the circle enclosed by these axial extensions is approximately equal to or less than the inner diameter of the piston, ensuring insertion of the mechanism into the piston while ensuring alignment between the mechanism and the piston axis. It will be appreciated that the alignment of the mechanism with the piston axis may not be exact, allowing for manufacturing clearance tolerances.

[0048] Alternatively, only one of these axial extensions has a rib or groove cooperating with the piston (for example a single rib or groove), this being sufficient to rotationally lock the sleeve with respect to the piston.

[0049] In the example illustrated, the device 14 comprises four axial extensions 32. Alternatively, the device 14 comprises three or more axial extensions. Preferably, these axial extensions are distributed evenly around the plate, at an angle.

[0050] Very advantageously, the plate 28 and these axial extensions 32 are made in one piece by cutting a sheet, bending and / or stamping a sheet of steel.

[0051] The production of the device 14 is therefore relatively simple and inexpensive.

[0052] After cutting, these extensions extend radially from the plate, generally having a four-pointed star shape.

[0053] In this example, a cut 44 is made at the attachment of the axial extensions 32 to the plate 28, thereby reducing the force required to bend during bending and limiting the appearance of "material bulging".

[0054] In Figure 3 , it can be seen that Figure 2 the mechanism is mounted in the piston, in which the axial extensions 32 form legs to ensure alignment of the sleeve and the drive member with the piston axis.

[0055] This further facilitates assembly of the brake. Indeed, as Figure 3 depicted in , when the piston is mounted in the caliper housing 7, the end 19 of the drive member slides along the longitudinal axis AX of the housing 7 and is automatically aligned with the hole 27 of the caliper body, which is aligned with the axis AX.

[0056] Alternatively, the rotational clamping is achieved by making the radial protrusion of the plate extend in the plane of the plate and cooperate with an axial groove in the piston, and the aligned retention is achieved by making the axial extensions have an arc-shaped shape in section with a radius corresponding to the internal radius of the piston housing.

[0057] Figure 4 In , another schematic embodiment of the device 114 can be seen, in which, after cutting, the extensions 132 extend approximately tangentially to a circle centered on the longitudinal axis.

[0058] Figure 2 During bending, each axial extension 132 is bent around an approximately radial axis closer to the longitudinal axis, unlike in , in which the extensions are each bent around an axis tangent to the circle circumscribed by the plate.

[0059] Furthermore, in this example, the rotational locking of the sleeve with respect to the piston is achieved by making the radial protrusions 134 carried by the plate cooperate with axial grooves carried by the inner surface of the piston skirt. Alternatively, the extensions 132 can also be made to operate so as to ensure the rotational locking.

[0060] In this example, the faces of the axial extensions that cooperate with the inner surface of the piston skirt are flat.

[0061] In Figure 5 Another schematic embodiment of the device 214 can be seen in which, after cutting, the extensions 232 extend substantially radially.

[0062] During the bending, each axial extension 232 is bent around an axis that is tangent to a circle centered on the longitudinal axis, closer to the longitudinal axis.

[0063] The rotational locking of the sleeve with respect to the piston is improved by making the radial recesses or notches 234 carried by the plate cooperate with axial ribs carried by the inner surface of the piston skirt. These radial recesses are achieved by cutting. Alternatively, the extensions 232 can also be made to operate so as to ensure the rotational locking.

[0064] In this example, the faces of the axial extensions that cooperate with the inner surface of the piston skirt are flat.

[0065] In Figure 5 In the example shown, four longitudinal extensions 232 are provided. Furthermore, two of the four extensions have an enlarged region 236 at approximately the middle length, i.e. the transverse dimension of this enlarged region is greater than the transverse dimension of the rest of the extension. The enlarged portion is arranged in the plane of the longitudinal extension.

[0066] The advantage of this example embodiment is that the mass of the embodiment is reduced, thus reducing the unsprung mass and improving the stability of the vehicle.

[0067] Very advantageously, the device 14, 114, 214 is made by cutting and bending and / or stamping a sheet of steel.

[0068] Advantageously, the ratio of the length of the axial extensions to the length of the piston and / or of the screw connection mechanism is between 1 / 4 and 3 / 4, preferably approximately 1 / 2.

[0069] In the example shown, all the axial extensions have the same length. Alternatively, they have different lengths.

[0070] An example of an assembly method will now be described.

[0071] Consider Figure 2 the mechanism shown:

[0072] The drive member is screwed into the sleeve 13, thus forming a screw connection mechanism.

[0073] The screw connection mechanism is then inserted into the piston by aligning the axial extension with the ribs of the piston skirt. The mechanism is then slid into the piston. The axial extension cooperates with the piston skirt to ensure rotational clamping of the sleeve and to maintain alignment between the drive member and the piston axis.

[0074] In the next step, the piston equipped with the screw connection mechanism is inserted into the caliper bore. The caliper is slid into the bore. Since the drive member is aligned with the piston axis and thus also with the bore axis, the end 19 of the drive member 11 is aligned with the hole 27 in the caliper and naturally enters the hole. The electric motor is then mounted outside the caliper and the shaft of the electric motor is connected to the end 19 of the drive member.

[0075] By virtue of the invention, the installation is simplified and can be automated.

[0076] Terminology:

[0077] 1 brake

[0078] 2 caliper

[0079] 3 caliper body

[0080] 4 pad

[0081] 5 pad

[0082] 6 disc

[0083] 7 housing

[0084] 8 piston

[0085] 9 mechanism

[0086] 11 drive

[0087] 13 sleeve

[0088] 14 rotational locking and axial holding device

[0089] 16 skirt

[0090] 17 threaded body

[0091] 18 free end

[0092] 19 coupling end

[0093] 21 head

[0094] 22 flat bottom

[0095] 23 bearing surface

[0096] 24 bearing washer

[0097] 26 wall

[0098] 27 aperture

[0099] 28 plate

[0100] 30 central aperture

[0101] 32 axial extension

[0102] 34 head

[0103] 36 body

[0104] 40 axial groove

[0105] 42 axial rib

[0106] 44 cutout

[0107] 46 plate aperture

[0108] 114, 214 rotational locking and axial retention device

[0109] 128 plate

[0110] 132, 232 axial extension

[0111] 134 radial extension

[0112] 234 radial recess

[0113] 236 enlarged region

Claims

1. A screw connection mechanism for a piston of an electromechanical brake, the screw connection mechanism being configured to be mounted in the piston (8), wherein the screw connection mechanism comprising a sleeve (13) and a drive member (11) cooperating by a screw connection having a longitudinal axis (AX), wherein the drive member comprises a head (21) and a rotation locking and axial holding device (14, 114) for rotationally locking the sleeve relative to the piston about the longitudinal axis (AX) and axially holding the screw connection mechanism, wherein the rotation locking and axial holding device (14, 114) comprises a plate (28, 128) attached to the sleeve (13) and extending orthogonally to the longitudinal axis (AX), characterized in that the rotation locking and axial holding device comprises at least three axial extensions (32, 132) cooperating with axial walls of the piston and at least one radial shape (40, 134) cooperating with axial walls of the piston, wherein the axial extensions (32, 132) extend from a radially outer periphery of the plate (28, 128) towards the head (21), wherein the axial extensions (32, 132) form legs configured to ensure an axial alignment of the sleeve (13) and the drive member (11) with the piston (8).

2. The helical connection mechanism of claim 1, wherein, The at least one radial shape (40) is carried by an axial extension (32).

3. The helical connection mechanism of claim 2, wherein, The at least one radial shape (40) is a groove or rib axially extending along an axial extension (32).

4. The helical connection mechanism of claim 1, wherein, The at least one radial shape (134) is a protrusion or recess in an outer edge of the plate (128).

5. The helical connection mechanism of claim 1, wherein, The rotation locking and axial holding device (14, 114) is made by cutting and bending a sheet metal.

6. A caliper (2) for an electromechanical brake (1), the caliper comprising a caliper body (3) comprising: a housing (7) enclosing a piston (8) and a screw connection mechanism, wherein the piston comprises an inner housing delimited by a bottom and a side wall (16) and a screw connection mechanism according to claim 1, wherein the side wall has in its inner surface at least one axial shape (42) cooperating with the radial shape (40, 134), wherein the at least one axial shape (42) axially extends over the entire axial dimension of the inner surface of the side wall (16).

7. A disc brake comprising a caliper according to claim 6 and an electric motor connected to the drive member.

8. A method for manufacturing a screw connection mechanism according to claim 1, the method comprising: a) providing a sleeve (13) and a drive member (11) and assembling the sleeve (13) and the drive member (11), b) cutting a sheet metal into a sheet shape comprising the plate (28, 128) and an elongated portion, c) deforming the elongated portion so as to form the axial extensions (32, 132), d) attaching the sheet shape to the sleeve (13).

9. The manufacturing method according to claim 8, wherein, Said sheet shape comprises at least one radial shape and an elongated portion tangent to said plate.

10. The manufacturing method according to claim 9, wherein, Step c) comprises bending to fold said elongated portion around an axis extending radially with respect to said longitudinal axis (AX).

11. The manufacturing method according to claim 8, wherein, Said sheet shape comprises an elongated portion extending radially.

12. The manufacturing method according to claim 11, wherein, Step c) comprises bending to fold said elongated portion around an axis tangent to a circle circumscribed by said plate, and stamping at least one elongated portion to form said at least one radial shape.

13. The manufacturing method of claim 8, wherein, Step c) comprises deforming said elongated portion so as to form said at least one radial shape (40, 134).

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