Brake unit for a motor vehicle braking system

Abstract

The invention relates to a brake device (1) for a motor vehicle braking system, comprising a housing (2) with a cylinder bore (3) in which a cylinder piston (4) is axially displaceable along a central axis (M) in an actuation direction (B) and in a release direction (L) opposite to the actuation direction (B), wherein the cylinder piston (4) defines a hydraulic pressure chamber and is connected to an actuating rod (6) via an actuating force-transmitting coupling element (5), wherein a stop surface (8), in particular a rigid one, is provided for the cylinder piston (4) to define an unactuated starting position of the cylinder piston (4), and wherein a damping element (13) is provided for damping a cylinder piston stop. According to the invention, the stop surface (8) is formed integrally on a housing component (7), wherein the damping element (13) is attached to the coupling element (5).

Description

[0001] The invention relates to a brake device for a motor vehicle braking system, wherein the brake device comprises a housing with a cylinder bore in which a cylinder piston is arranged to be axially displaceable along a central axis in an actuation direction and in a release direction opposite to the actuation direction, wherein the cylinder piston defines a hydraulic pressure chamber and is connected to an actuating rod via a coupling element that transmits actuation forces, wherein a stop surface, in particular a rigid one, is provided for the cylinder piston to define an unactuated starting position of the cylinder piston, and wherein a damping element is provided to dampen a cylinder piston stop.

[0002] In motor vehicles, braking systems with a braking device are typically used to decelerate the vehicles in a controlled manner. Usually, hydraulic pressure is built up in the braking system via a pressure medium, in particular brake fluid, which then results in a braking force at the wheel brakes of the vehicle and thus ultimately in the deceleration of the vehicle.

[0003] The braking system can be designed according to the brake-by-wire principle, whereby a driver's braking request or a braking force demand is sensed and converted into actual brake application by means of an electric or electrically actuated pressure source. A brake-by-wire braking system typically has a hydraulic fallback system, i.e., an operating mode in which a brake pedal is hydraulically and / or mechanically coupled to the wheel brakes if the "by-wire" operating mode fails or malfunctions, particularly if pressure build-up is no longer possible via the pressure source. While in normal operation a pedal decoupling unit provides hydraulic decoupling between brake pedal actuation and brake pressure build-up, this decoupling is eliminated in the fallback system.However, the braking system can also be designed in a pure brake-by-wire version, so that a corresponding hydraulic pressure can be built up solely by the electrically actuated pressure source and a manual or hydraulic fallback level is dispensed with.

[0004] Such braking systems require, in particular for reliable control, calibration, and detection of the driver's braking request, knowledge of the exact relative position of the brake cylinder piston in its unactuated starting position – the zero or reference point. To avoid the effort required for complex sensing and spatial calibration, it is known to provide a stationary mechanical stop for the cylinder piston, which defines the aforementioned zero or reference point and serves, in particular, as the measurement origin for an electronic control system.

[0005] However, such vacuum-assisted braking systems, unlike conventional braking systems with a vacuum booster, inherently exhibit relatively low damping. This leads, for example, to a high return velocity of the cylinder piston and the associated massive mechanical actuating components, such as the actuating rod and brake pedal, when the brake pedal is released quickly after braking. This results in a clunking noise when the piston hits the mechanical stop, which can be perceived as disturbing.

[0006] It is therefore already known to use a damping element, such as a rubber disc, for impact damping. For example, DE 10 2017 218 768 A1 discloses a braking device of the type mentioned above, which has a separate stop disc, designed as an independent component, for limiting the movement of a cylinder piston in a release direction and thereby defining its unactuated starting position. The stop disc also has an elastomeric coating for impact damping.

[0007] A disadvantage of this design is the associated high number of individual parts and joining or assembly steps. Furthermore, assembling and reliably fixing the separate components, especially a separate disc- or ring-shaped damping element, in the confined and difficult-to-access housing interior, particularly in the area of ​​the rear end of the cylinder piston, presents a significant challenge and therefore represents a considerable effort. This results in complex manufacturing and high production costs.

[0008] Against this background, the object of the invention is to provide an improved braking device for a motor vehicle braking system, which comprises a simple and compact design and has as few individual parts and joining or assembly steps as possible in the manufacturing process, and is therefore particularly easy and cost-effective to manufacture, and which in operation provides sufficient and reliable damping of a cylinder piston impact, in particular a reduction of impact noise.

[0009] The foregoing problem is solved by the teaching of claim 1. Advantageous embodiments and further developments of the invention are set forth in the dependent claims and the following description.

[0010] Accordingly, a brake device for a motor vehicle brake system comprises a housing with a cylinder bore in which a cylinder piston is arranged to be axially displaceable along a central axis in an actuation direction and in a release direction opposite to the actuation direction, wherein the cylinder piston defines a hydraulic pressure chamber and is connected to an actuating rod via a coupling element that transmits actuation forces, wherein a stop surface, in particular a rigid one, is provided for the cylinder piston to define an unactuated starting position of the cylinder piston, and wherein a damping element is provided to dampen a cylinder piston stop.

[0011] According to the invention, the stop surface is formed integrally on a housing component and the damping element is attached to the coupling element.

[0012] The invention is based in particular on the idea of ​​not providing a separate, additional component for forming the stop surface, but rather forming the stop surface integrally with the existing housing component, and by attaching the damping element to the coupling element forming a single (common) assembly consisting of the coupling element and the damping element, which can be manufactured and handled, and in particular assembled, as a pre-assembled unit.

[0013] The embodiment according to the invention thus has the overall advantage that it provides an improved braking device which comprises a simple and compact design and which has as few individual parts and joining or assembly steps in the manufacturing process as possible, and is therefore particularly easy and cost-effective to manufacture, and which in operation has sufficient and reliable damping of a cylinder piston stop, in particular a reduction of a stop noise.

[0014] Advantageously, the actuating rod is connected to a brake pedal.

[0015] The coupling element allows the corresponding actuating force to be transmitted directly to the cylinder piston, particularly when the actuating rod is actuated, preferably when a brake pedal connected to the actuating rod is actuated. The coupling element is advantageously arranged or attached to an end region of the actuating rod on the cylinder-piston side, and is particularly tiltable to a limited extent.

[0016] The housing component and / or the stop surface is located, in particular, in an axial end region of the cylinder bore facing away from the pressure chamber. The stop surface limits the movement of the cylinder piston in the release direction and thereby defines its unactuated starting position.

[0017] The damping element is designed in particular to introduce a force directed from the cylinder piston in the release direction into the housing component and thereby to at least partially absorb this force, and / or is designed to mechanically decouple the coupling element from the housing component or stop surface.

[0018] In particular, the coupling element and the damping element are originally two different, separate components which have been joined together, preferably inseparably, to form a pre-assembled unit in a manufacturing or assembly process.

[0019] In an advantageous embodiment, in the unactuated starting position, the cylinder piston is axially supported against the stop surface via the coupling element and the damping element. Thus, in the unactuated starting position, the damping element rests, in particular directly, at least partially against the stop surface.

[0020] In a further advantageous embodiment, the damping element is attached directly to the coupling element. Thus, the damping element is attached directly to the coupling element; in particular, no other components are arranged between the damping element and the coupling element.

[0021] In a further advantageous embodiment, the damping element is attached to the coupling element by means of a material-bonded connection and / or a positive-locking connection. Thus, the damping element is connected to the coupling element by a material-bonded connection and / or a positive-locking connection. Preferably, the coupling element has a groove in which the damping element is at least partially arranged in a positive-locking manner.

[0022] In a further advantageous embodiment, the damping element is attached to the coupling element by means of an injection molding process, in particular by means of overmolding; preferably, the damping element is applied to at least a partial area of ​​the surface of the coupling element by means of an injection molding process, in particular overmolding.

[0023] In a further advantageous embodiment, the damping element is designed to be elastically reversibly compressible in the axial direction. In particular, the damping element is designed as a solid element that is elastically and reversibly deformable in the axial direction.

[0024] In a further advantageous embodiment, the damping element is manufactured in one piece from a material with a higher material damping compared to a material of the coupling element, wherein the damping element is preferably made of an elastic material, preferably an elastomer, plastic or rubber, in particular a high-hard rubber.

[0025] In a further advantageous embodiment, the damping element is ring-shaped, with a cross-section of the damping element preferably tapering from the coupling element towards the stop surface.

[0026] In a further advantageous embodiment, the damping element is arranged at the axial end region of the coupling element facing the stop surface. In other words, the damping element is thus arranged at the axial end region of the coupling element facing away from the pressure chamber.

[0027] In a further advantageous embodiment, a rear surface is formed on the coupling element for transmitting forces from the cylinder piston in the release direction into the housing component. Advantageously, a front surface is also formed on the coupling element for transmitting actuating forces in the actuating direction into the cylinder piston.

[0028] In a further advantageous embodiment, a radial flange is formed on the axial end region of the coupling element facing the actuating rod, with the rear surface being arranged on the radial flange. The radial flange is thus designed as a flange extending radially outwards, and in particular as a completely circumferential flange. The radial flange is specifically designed as a completely circumferential radial collar. In an advantageous embodiment in which a front surface for introducing actuating forces in the actuating direction into the cylinder piston is also formed on the coupling element, the rear surface and the front surface are arranged on the radial flange.

[0029] In a further advantageous embodiment, the damping element is attached to the back surface. Accordingly, the damping element is arranged axially, and in particular directly, between the back surface and the stop surface. Preferably, the back surface has a groove in which the damping element is at least partially and positively engaged.

[0030] In a further advantageous embodiment, the housing component has a circumferential support projection extending radially inwards, particularly into the cylinder bore, which at least partially forms the stop surface. The support projection is particularly designed as an annular and / or fully circumferential support projection.

[0031] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 in a longitudinal section view a partial representation of a braking device according to the invention in an unactuated starting position, and Fig. 2 in a longitudinal section view the coupling element with the damping element of the brake device attached to it according to Fig. 1.

[0032] Corresponding parts in all figures are always marked with the same reference symbols.

[0033] In Fig. Figure 1 shows a sectional view of an embodiment of a brake device 1 according to the invention for a motor vehicle brake system in an unactuated initial position.

[0034] The brake device 1 has a housing 2 with a cylinder bore 3. A cylinder piston 4 is axially displaceable in the cylinder bore 3 along a central axis M in an actuation direction B and in a release direction L opposite to the actuation direction B. The cylinder piston 4 is connected to an actuating rod 6 via a coupling element 5 that transmits actuating forces. The cylinder piston 4 defines a hydraulic pressure chamber (not shown) located at an end region of the cylinder bore 3 opposite the actuating rod 6. The coupling element 5 is tiltably mounted to an end region of the actuating rod 6 on the cylinder piston side. The actuating rod 6 is connected at its end opposite the cylinder piston 4 to a brake pedal (not shown).Via the coupling element 5, the corresponding actuating force can be transmitted directly to the cylinder piston 4 when the brake pedal connected to the actuating rod 6 is actuated.

[0035] To define an unactuated starting position of the cylinder piston 4, a stop surface 8 is formed in one piece on a rigid housing component 7, which is arranged in an axial end region of the cylinder bore 3 facing away from the pressure chamber. For this purpose, the housing component 7 has a circumferential support projection 9 extending radially inwards into the cylinder bore 3, which at least partially forms the stop surface 8. The stop surface 8 limits the movement of the cylinder piston 4 in the release direction L and thereby defines its unactuated starting position.

[0036] A radial and fully circumferential flange 10 is formed on the axial end region of the coupling element 5 facing the actuating rod 6. The flange 10 has a rear surface 11 for transmitting forces from the cylinder piston 4 in the release direction L into the housing component 7 and a front surface 12 for transmitting actuating forces in the actuating direction B into the cylinder piston 4.

[0037] A damping element 13 for damping a cylinder piston stop is directly attached to the rear surface 11 of the flange 10. For this purpose, the rear surface 11 has a fully circumferential groove 14 in which the damping element 13 is at least partially arranged in a form-fitting manner. The damping element 13 is manufactured in one piece from a high-hardness rubber and is designed to be ring-shaped and elastically reversible in the axial direction, with a cross-section of the damping element 13 tapering from the rear surface 11 of the flange 10 towards the stop surface 8.

[0038] The damping element 13 is thus arranged axially directly between the rear surface 11 of the coupling element 5 and the stop surface 8. In the unactuated starting position of the cylinder piston 4, it is therefore indirectly supported axially against the stop surface 8 via the coupling element 5 and the damping element 13, which is attached to the rear surface 11 of the flange 10 of the coupling element 5. Thus, in the unactuated starting position, the damping element 13 rests directly, at least partially, against the stop surface 8. In particular, the damping element 13 transmits corresponding impact forces from the cylinder piston 4 into the housing component 7 and partially absorbs them, thereby reliably damping the impact.

[0039] The coupling element 5 and the damping element 13 are originally two different, separate components which, prior to assembly into the housing 2, have already been inseparably joined together in a manufacturing process to form an easily handled or mountable pre-assembly unit, wherein the damping element 13 is applied to the rear surface 11 of the flange 10 of the coupling element 5 by means of an injection molding process, for example by means of overmolding, and is in particular arranged in the groove 14.

[0040] By such a design of the brake device 1, an improved brake device 1 is provided, which comprises a simple and compact design and which has as few individual parts and joining or assembly steps in the manufacturing process as possible and is therefore particularly easy and cost-effective to manufacture and which in operation has sufficient and reliable damping of a cylinder piston stop, in particular a reduction of a stop noise.

[0041] In Fig. 2 is, in a longitudinal section view, the coupling element 5 with attached damping element 13 of the brake device 1 according to Fig.Figure 1 shows in particular the direct attachment of the damping element 13 to the rear surface 11 of the flange 10 of the coupling element 5, wherein the damping element 13 is arranged in the groove 14 in a form-fitting manner, and wherein the coupling element 5 with the damping element 13 attached to it thus forms a (common) assembly unit, which is manufactured and handled as a pre-assembled unit, in particular mountable in the housing 2. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 218 768 A1

[0006]

Claims

[1] Brake device (1) for a motor vehicle brake system, comprising a housing (2) with a cylinder bore (3) in which a cylinder piston (4) is arranged to be axially displaceable along a central axis (M) in an actuation direction (B) and in a release direction (L) opposite to the actuation direction (B), wherein the cylinder piston (4) defines a hydraulic pressure chamber and is connected to an actuating rod (6) via an actuating force-transmitting coupling element (5), wherein a stop surface (8), in particular a rigid one, is provided for the cylinder piston (4) to define an unactuated starting position of the cylinder piston (4), and wherein a damping element (13) is provided to dampen a cylinder piston stop, characterized by , that the stop surface (8) is formed in one piece on a housing component (7), and that the damping element (13) is attached to the coupling element (5). [2] Brake device (1) according to claim 1, characterized by, that in the unactuated starting position the cylinder piston (4) is indirectly supported axially on the stop surface (8) via the coupling element (5) and the damping element (13). [3] Brake device (1) according to claim 1 or 2, characterized by , that the damping element (13) is attached directly to the coupling element (5). [4] Brake device (1) according to any one of the preceding claims, characterized by , that the damping element (13) is attached to the coupling element (5) by means of a material-bonded connection and / or a form-fit connection. [5] Brake device (1) according to any one of the preceding claims, characterized by , that the damping element (13) is attached to the coupling element (5) by means of an injection molding process, in particular by means of overmolding, preferably applied to at least a partial area of ​​the surface of the coupling element (5). [6] Brake device (1) according to any one of the preceding claims, characterized by, that the damping element (13) is designed to be elastically reversibly compressible in the axial direction. [7] Brake device (1) according to any one of the preceding claims, characterized by , that the damping element (13) is made in one piece from a material with a higher material damping compared to a material of the coupling element (5), wherein preferably the damping element (13) is made from an elastic material, preferably from an elastomer, plastic or rubber. [8] Brake device (1) according to any one of the preceding claims, characterized by , that the damping element (13) is designed in a ring shape, wherein preferably a cross-section of the damping element (13) tapers from the coupling element (5) towards the stop surface (8). [9] Brake device (1) according to any one of the preceding claims, characterized by , that the damping element (13) is arranged at the axial end region of the coupling element (5) facing the stop surface (8). [10] Brake device (1) according to any one of the preceding claims, characterized by , that a rear surface (11) is formed on the coupling element (5) for introducing forces from the cylinder piston (4) in the release direction (L) into the housing component (7). [11] Brake device (1) according to claim 10, characterized by , that a radial flange (10) is formed on the axial end region of the coupling element (5) facing the actuating rod (6), wherein the rear surface (11) is arranged on the radial flange (10). [12] Brake device (1) according to one of claims 10 or 11, characterized by , that the damping element (13) is attached to the rear surface (11). [13] Brake device (1) according to any one of the preceding claims, characterized by , that the housing component (7) has a radially inwardly projecting circumferential support projection (9), in particular into the cylinder bore (3), which at least partially forms the stop surface (8).

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