BRAKE PISTON, METHOD FOR MANUFACTURING A BRAKE PISTON, AND BRAKE CALIPER

Abstract

A brake piston is described which comprises a first tubular piston body portion and a second tubular piston body portion. The second piston body portion is connected to the first piston body portion and lies, in an axial view, radially completely inside the first piston body portion, thus forming an annular hollow space. Furthermore, a length of the second piston body portion along a piston longitudinal axis is at least 50% of a length of the first piston body portion. An inner circumferential surface of the second piston body portion comprises an anti-rotation contour which also forms an axial guide contour for a brake piston drive. Moreover, a method for manufacturing such a brake piston is explained. A brake caliper for a disk brake of a vehicle is also presented, which brake caliper comprises such a brake piston.

Claims

1. A brake piston (20), in particular for a disk brake of a vehicle, comprising a first tubular piston body portion and a second tubular piston body portion, both of which extend along a piston longitudinal axis, the second piston body portion being connected to the first piston body portion and lying, in an axial view, radially completely inside the first piston body portion, thus forming an annular hollow space between the first piston body portion and the second piston body portion, wherein a length of the second piston body portion along the piston longitudinal axis is at least 50% of a length of the first piston body portion, and an inner circumferential surface of the second piston body portion comprises an anti-rotation contour for a brake piston drive, which anti-rotation contour also forms an axial guide contour for the brake piston drive.

2. The brake piston according to claim 1, wherein the first piston body portion and the second piston body portion are connected via an annular front wall portion.

3. The brake piston according to claim 1, wherein the second piston body portion is axially closed at one end by a base portion.

4. The brake piston according to claim 2, wherein the base portion and the front wall portion are arranged at axially opposite ends of the second piston body portion.

5. The brake piston according to claim 4, wherein the base portion is flat, conical or frustoconical.

6. The brake piston according to claim 1, wherein a pressure surface for acting on a brake pad is positioned at one axial end of the first piston body portion.

7. The brake piston according to claim 6, wherein the pressure surface and an axially outer end surface of the base portion lie substantially in one plane.

8. The brake piston according to claim 1, wherein the second piston body portion is elastically displaceable in then axial direction with respect to the first piston body portion.

9. The brake piston according to claim 1, wherein the second piston body portion is shaped conically with respect to the piston longitudinal axis.

10. The brake piston according to claim 1, wherein the second piston body portion has a polygonal cross section.

11. The brake piston according to claim 1, wherein the brake piston has a substantially constant wall thickness.

12. The brake piston according to claim 1, wherein the brake piston is manufactured in one piece.

13. A method for manufacturing a brake piston according to claim 1, wherein the brake piston or brake piston parts is/are manufactured by deep drawing a tube that is closed at one end or a disk, it being possible to produce the anti-rotation contour and the axial guide contour the deep drawing.

14. The method for manufacturing a brake piston according to claim 1, wherein the brake piston or brake piston parts is/are manufactured by a forming or deep drawing method, a casting method or a 3D-printing method.

15. A brake caliper for a disk brake of a vehicle, comprising a brake piston according to claim 1, wherein the brake piston is slidably accommodated in a cylindrical opening and/or wherein the brake piston is coupled to a brake piston drive comprising a spindle drive.

16. The brake caliper according to claim 15, wherein the brake piston drive has a cross-sectional geometry that is complementary to the anti-rotation contour in the region with which the brake piston drive protrudes into the anti-rotation contour.

17. The brake piston according to claim 6, wherein an axially outer end surface of the base portion is set back axially with respect to the pressure surface.

18. The brake piston according to claim 11, wherein the brake piston is a sheet metal component.

19. The brake piston according to claim 12, wherein the brake piston is one of a deep-drawn part, a cast part or a 3D-printed part.

20. The brake piston according to claim 3, wherein the base portion and the front wall portion are arranged at axially opposite ends of the second piston body portion.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0038] The disclosure is explained below with reference to various exemplary arrangements which are shown in the accompanying drawings, in which:

[0039] FIG. 1 is a partial sectional view of a brake caliper according to the disclosure comprising a brake piston according to the disclosure, which brake piston has been manufactured by a method according to the disclosure, a portion of a brake disk also being shown,

[0040] FIG. 2 shows the brake piston according to the disclosure from FIG. 1 together with components of a brake piston drive designed as a spindle drive,

[0041] FIG. 3 is an isolated view of the brake piston from FIGS. 1 and 2,

[0042] FIG. 4 is a view of the brake piston from FIG. 1 to 3 along a direction IV from FIG. 3,

[0043] FIG. 5 is a perspective view of the brake piston from FIG. 1 to 4,

[0044] FIG. 6 is a different perspective view of the brake piston from FIG. 1 to 4, and

[0045] FIG. 7 is a view, corresponding to FIG. 2, of a variant of the brake piston according to the disclosure.

DETAILED DESCRIPTION

[0046] FIG. 1 shows a brake caliper 10 of a disk brake of a vehicle, which brake caliper interacts with a brake disk 12.

[0047] The brake caliper 10 comprises a brake caliper body 14 to which a first brake pad 16 is fastened. The first brake pad 16 is thus held immovably on the brake caliper body 14.

[0048] In addition, a second brake pad 18 is provided which is slidably mounted on the brake caliper body 14 so that it can optionally be pressed against the brake disk 12 by a brake piston 20 in order to achieve a braking effect.

[0049] For this purpose, the brake piston 20 is slidably mounted in a cylindrical opening, in this case e.g. a fluid cylinder 22, which is formed on the brake caliper body 14.

[0050] In this case, a pressure chamber 24 to which pressurized fluid can be supplied is delimited by an end of the fluid cylinder 22 facing away from the brake disk 12 and by the brake piston 20.

[0051] The pressure chamber 24 is fluidically connected to a pressurized fluid connection 26 via which a pressurized fluid can optionally be introduced into the pressure chamber 24 and discharged therefrom.

[0052] The pressurized fluid is a hydraulic fluid, for example. The fluid cylinder 22 is therefore a hydraulic cylinder.

[0053] The brake piston 20 can therefore be moved hydraulically toward the brake pad 18 and the brake disk 12, so that the brake pad 18 abuts against the brake disk 12 and brakes it.

[0054] Moreover, the brake piston 20 is coupled to a brake piston drive 28 which, in the exemplary arrangement shown, is a spindle drive.

[0055] It should be emphasized, however, that the brake piston having the functions described above and below can also be used in a purely electromechanical brake and is accommodated in this case in a cylindrical opening which can be designed as a bore or as an opening in a tubular cylinder.

[0056] In this context, a spindle nut 30 of the spindle drive is mounted on the brake piston 20 such that it cannot be rotated but can be slid axially along a piston longitudinal axis 32.

[0057] The spindle nut 30 interacts with a spindle 34 of the spindle drive, which spindle is mounted on the brake caliper body 14 such that it can be rotated about the piston longitudinal axis 32 but is otherwise stationary. The spindle 34 can optionally be set in rotation by an electric drive motor 36.

[0058] The brake piston 20 can therefore also be moved toward the brake pad 18 and the brake disk 12 by the brake piston drive 28 designed as a spindle drive, so that the brake pad 18 is pressed against the brake disk 12 and brakes it.

[0059] The brake piston 20 is shown in detail in FIG. 2 to 6. In addition, the spindle nut 30 and the spindle 34 can be seen in FIG. 2.

[0060] In this context, in one exemplary arrangement, the brake piston 20 is substantially composed of a first tubular piston body portion 38 and a second tubular piston body portion 40.

[0061] The two piston body portions 38, 40 extend along the piston longitudinal axis 32.

[0062] The second piston body portion 40 is in this exemplary arrangement is designed to be slightly conical with respect to the piston longitudinal axis 32. Starting from the end which is arranged adjacent to the brake piston drive 28, the cross section of said second piston body portion decreases in the direction of the end on the brake pad side.

[0063] Furthermore, the second piston body portion 40 is arranged, in an axial view, radially completely inside the first piston body portion 38, thus forming an annular hollow space 42. In other words, the second piston body portion 40 lies completely inside the first piston body portion 38 when the brake piston 20 is viewed along the piston longitudinal axis 32.

[0064] In the exemplary arrangement shown, the second piston body portion 40 also lies axially completely inside the first piston body portion 38. This means that the second piston body portion 40 does not project axially beyond the first piston body portion 38. This applies to both axial ends of the second piston body portion 40.

[0065] In this case, the first piston body portion 38 and the second piston body portion 40 are connected to one another via an annular front wall portion 44. The annular front wall portion 44 thus also delimits the hollow space 42 in the axial direction.

[0066] In addition, the second piston body portion 40 is axially closed, by a base portion 46, at its end opposite the front wall portion 44 along the piston longitudinal axis 32.

[0067] In the exemplary arrangement shown, the base portion 46 is frustoconical. It goes without saying, however, that this base portion can also be shaped differently, e.g. so as to be flat or conical.

[0068] In the exemplary arrangement shown, a length L2 of the second piston body portion 40 is 70% to 80% of a length L1 of the first piston body portion 38 (see FIG. 3).

[0069] Of course, other lengths L2 of the second piston body portion 40 are also possible. As will become clear from the following explanation, however, a minimum length must be specified. Overall, a length L2 of the second piston body portion 40 along the piston longitudinal axis 32 is at least 50% of the length L1 of the first piston body portion 38.

[0070] The second piston body portion 40 and the base portion 46 together form a cavity in which the spindle nut 30 is received.

[0071] An inner circumferential surface 48 of the second piston body portion 40 has an anti-rotation contour 50.

[0072] In the exemplary arrangement shown, the anti-rotation contour 50 is formed by the second piston body portion having an octagonal cross section (see in particular FIG. 5).

[0073] The spindle nut 30, which represents a region of the brake piston drive 28 which protrudes into the anti-rotation contour 50, has a complementary cross-sectional geometry, i.e. is also octagonal. This means that the spindle nut 30 cannot be rotated relative to the brake piston 20.

[0074] However, the spindle nut 30 can be slid along the piston longitudinal axis 32 within the second piston body portion 40.

[0075] The inner circumferential surface 48 thus also forms an axial guide contour 52 for the brake piston drive 28, more precisely for the spindle nut 30.

[0076] The aforementioned conicity of the second piston body portion 40 is so slight that the spindle nut 30 can be guided over the entire length L2 due to the guide contour 52.

[0077] In addition, a pressure surface 54 is positioned at an axial end of the first piston body portion 38, which pressure surface is used to abut against the brake pad 18, i.e. to apply a force thereto.

[0078] The pressure surface 54 extends over the axial front surface of the first piston body portion 38 and over an annular pressure surface extension 56 extending radially inward from the front surface.

[0079] In order to increase the friction between the brake pad 18 and the pressure surface 54, said pressure surface is provided with radial grooves 58.

[0080] In order to prevent the brake piston 20 from rotating relative to the brake caliper body 14, said brake piston is non-rotatably connected e.g. to the brake pad 18, usually to the so-called back plate of the brake pad 18, via a mechanical coupling. For example, a projection is provided on the brake piston 20 or on the back plate, which projection engages in the other component of the brake piston 20 and back plate in order to produce a non-rotatable coupling.

[0081] The brake piston 20 is also designed in such a way that the pressure surface 54 and an axially outer end surface 60 of the base portion 46 lie substantially in one plane E (see FIGS. 2 and 3).

[0082] When the brake piston 20 is in operation, not only the pressure surface 54 but also the end surface 60 abuts against the brake pad 18.

[0083] As can be seen in particular from FIG. 3, the brake piston 20 has a substantially constant wall thickness d.

[0084] In this exemplary arrangement, the brake piston 20 is manufactured in one piece as a sheet metal component.

[0085] In the exemplary arrangement shown, the brake piston 20 is manufactured by a deep drawing method.

[0086] A disk is used as the starting material.

[0087] This is first formed into a cup or a tube that is closed at one end. A lateral surface of the cup or the tube substantially corresponds to the first piston body portion 38 in terms of its outer contour.

[0088] A central base region of the cup or the tube is then deformed in the direction of the interior of the cup or the tube. This produces the second piston body portion 40 and the base portion 46.

[0089] The regions of the base of the cup or tube that are not ultimately deformed form the annular front wall portion 44.

[0090] Optionally, the pressure surface extension 56 is lastly formed by an end of the first piston body portion 38 opposite the front wall portion 44 being formed radially inward.

[0091] Alternatively, a tube that is closed at one end can also be selected as the starting material. In the method described above, the first step in which the disk is deformed to form such a tube can then be omitted.

[0092] A variant of the brake piston 20 together with the spindle nut 30 and the spindle 34 is shown in FIG. 7.

[0093] The brake piston 20 according to the exemplary arrangement in FIG. 7 only differs from the brake piston 20 explained with reference to FIG. 1 to 6 in that the outer end surface 60 of the base portion 46 is set back axially with respect to the pressure surface 54, i.e. is set back along the piston longitudinal axis 32.

[0094] In the exemplary arrangement according to FIG. 7, in a situation in which the brake piston 20 acts on the brake pad 18, there is thus a free space between the end surface 60 of the base portion 46 and the brake pad 18. The second piston body portion 40 can therefore be displaced elastically toward the brake pad 18 in the axial direction with respect to the first piston body portion 38. This results in particular from an elastic deformation of the annular front wall portion 44.

[0095] This makes it possible for the brake piston 20 to abut against the brake pad 18 under elastic tension, for example when actuated by the brake piston drive 28 and in particular by the spindle nut 30.

[0096] The brake caliper 10 can be operated as follows.

[0097] Starting from the position of the brake piston 20 shown in FIG. 1, said brake piston can be moved to the left, for example by applying pressure to the pressure chamber 24, so that it abuts against the brake pad 18 and presses said brake pad against the brake disk 12. This creates a braking effect.

[0098] In this context, the brake piston drive 28 is not actuated, i.e. the spindle nut 30 does not move.

[0099] When moved in the direction of the brake pad 18, there is therefore a relative movement between the brake piston 20 and the spindle nut 30. This is made possible by the axial guide contour 52.

[0100] Alternatively, it is possible for the brake piston 20, starting from the position shown in FIG. 1, to be moved to the left by the brake piston drive 28. For this purpose, the electric drive motor 36 is activated and the spindle 34 is set in rotation. Once the spindle nut 30 is non-rotatably mounted on the brake piston 20 via the anti-rotation contour 50, the spindle nut 30 is thereby moved to the left. In this case, it is guided by the guide contour 52.

[0101] As soon as the spindle nut 30 strikes against the base portion 46 of the brake piston 20, it entrains the brake piston 20 with it as it moves to the left.

[0102] In so doing, the brake piston 20 abuts against the brake pad 18, which in turn is pressed against the brake disk 12 in order to produce a braking effect.

[0103] In this context, in addition to the aforementioned rotary coupling with the back plate, the brake piston 20 is frictionally held on the brake caliper body 14 as a result of its frictional contact with a seal 62, so that it does not rotate.

[0104] As soon as the brake piston 20 is in contact with the brake pad 18, this system also causes the brake piston to be secured against rotation within the brake caliper body 14.

[0105] If the brake piston is designed according to FIG. 7, the second piston body portion 40 and the base portion 46 can be moved a little further by elastically deforming the front wall portion 44 relative to the first piston body portion 38, the pressure surface 54 of which abuts against the brake pad 18. The brake piston 20 is thus placed under tension.