ELECTROMECHANICAL VEHICLE BRAKE

An electromechanical vehicle brake for a motor vehicle is disclosed, having a housing with a piston chamber containing gas, an actuating piston for a brake lining, and an electric motor for driving the actuating piston. The actuating piston can be moved optionally between a retracted position and an extended position, wherein the actuating piston is accommodated movably in the housing, such that an end of the actuating piston directed towards the brake lining protrudes from the housing and an opposite end of the actuating piston is accommodated in the housing. At least one venting unit is accommodated in the housing in order to allow a gas exchange between the piston chamber and the environment. The venting unit comprises a gas-permeable filter element and a holding element for the filter element, and the venting unit is fixed on the housing by the holding element.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Priority Application No. 102022134392.8, filed Dec. 21, 2022, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to an electromechanical vehicle brake for a motor vehicle.

BACKGROUND

Due to an electromechanical vehicle brake, it is possible to generate a braking force directly on the wheels of the vehicle.

Electromechanical vehicle brakes generally comprise a housing with a piston chamber containing gas, an actuating piston for a brake lining, and an electric motor for driving the actuating piston, wherein the actuating piston can be moved optionally between a retracted position and an extended position. In its extended position, the actuating piston presses a brake pad against a brake disc of a wheel brake.

The actuating piston is usually accommodated in a gas-tight manner in the piston chamber in order to avoid dirt or other contaminants as well as moisture entering the piston chamber.

Owing to the gas-tight accommodation of the actuating piston in the piston chamber, however, there is a change in the gas pressure in the piston chamber when a temperature change or a piston movement occurs. Such changes in the gas pressure promote wear of the vehicle brake.

Moreover, an increasing number of dynamic braking operations generates an increasing vacuum in the piston chamber on account of wear of the friction linings. However, the tightness of the piston chamber with respect to the environment can only be ensured up to a certain pressure difference between the internal pressure of the piston chamber and the environment. If the specific pressure difference is exceeded, there is the risk that leaks will occur and moisture and dirt particles will be sucked into the piston chamber, and this also promotes the wear of the electric motor vehicle brake.

SUMMARY

What is needed is an electromechanical vehicle brake which is optimized with regard to service life.

According to the disclosure, an electromechanical vehicle brake for a motor vehicle is disclosed, having a housing with a piston chamber containing gas, an actuating piston for a brake lining, and an electric motor for driving the actuating piston, wherein the actuating piston can be moved optionally between a retracted position and an extended position, wherein the actuating piston is movably accommodated in the housing, such that an end of the actuating piston directed towards the brake lining protrudes from the housing and an opposite end of the actuating piston is accommodated in the housing. At least one venting unit is accommodated in the housing in order to allow a gas exchange between the piston chamber and the environment, wherein the venting unit comprises a gas-permeable filter element and a holding element for the filter element, and the venting unit is fixed on the housing by the holding element.

The vehicle brake according to the disclosure has the advantage that the gas pressure in the piston chamber corresponds at least approximately to the ambient pressure. This means that pressure fluctuations in the piston chamber are reduced, thereby reducing a load on the components of the vehicle brake, which in turn has an advantageous effect on the service life of the vehicle brake. For example, a pressure difference between the piston chamber and the environment is avoided, thereby preventing leaks of the vehicle brake and thus minimizing the risk of moisture and dirt particles entering the piston chamber. In other words, the venting unit promotes pressure equalization between the piston chamber and the environment. In this way, the risk of condensation forming in the piston chamber is also minimized.

The filter element can be fixed to the housing in a simple manner by due to the holding element.

For example, the venting unit is pre-assembled, thus enabling it to be fixed to the housing in a single assembly step.

The filter element is configured to be impenetrable to dirt particles.

The gas contained in the piston chamber is, for example, air, for example, atmospheric air.

The gas exchange via the venting element can take place in both directions.

For example, the housing has at least one aperture, wherein the venting unit is accommodated in the at least one aperture or covers the at least one aperture.

Thus, the venting unit makes the aperture impenetrable to dirt particles.

The venting unit can be secured on an inner side or an outer side of the housing or protrude through the housing. This allows more flexible positioning of the venting unit.

For example, latching elements are integrally formed on the holding element, wherein the holding element protrudes through an aperture in the housing and is latched on the housing. As a result, the venting unit can be mounted easily and without the use of a separate fastening arrangement. Specifically, the venting unit can be inserted into the aperture and latched with a single movement of the hand.

According to a further exemplary arrangement, a thread is formed on the holding element, and the holding element is screwed into an aperture in the housing. A thread also enables the venting unit to be easily mounted in an aperture without the need for a separate fastening arrangement. In addition, a thread provides improved sealing between the housing and the venting unit.

According to another exemplary arrangement, the holding element is adhesively bonded or welded to the housing. Particularly good sealing between the housing and the venting unit is likewise achieved by this arrangement.

The filter element is, for example, overmoulded along its outer edge with the material that forms the holding element. The filter element is thus secured on the holding element in a reliable manner. Moreover, leaks along an outer edge of the filter element are avoided.

Alternatively, the filter element can be adhesively bonded or welded to the holding element.

By way of example, a seal is arranged between the venting unit and the housing, for example between the holding element and the housing. The seal ensures that pressure equalization between the piston chamber and the environment takes place via the filter element and not via any gap that may occur between the venting unit and the housing. The seal is present especially when the venting unit is latched in the housing or, in other words, when there is no material bond between the venting unit and the housing or when the venting unit is not screwed into the housing.

A collar can be integrally formed on the housing, and the venting unit can be surrounded by the collar. The collar thus shields the venting element laterally, thereby protecting the venting unit from mechanical damage.

At least one venting channel is formed in the holding element, which channel is covered by the filter element. As a result, the venting channel is impenetrable to dirt particles, but gas-permeable.

A support surface for the filter element is preferably formed on the holding element. To be more precise, the filter element rests on the holding element adjacent to the at least one venting channel, as a result of which the filter element is supported and elastic deformation of the filter element is limited. This extends the service life of the filter element.

The presence of a plurality of venting channels in the holding element is advantageous compared to a single venting channel with the same overall flow cross section in terms of supporting the filter element, since in this case support surfaces for the filter element are present between the venting channels.

In an alternative exemplary arrangement, the filter element is supported by the housing.

According to one exemplary arrangement, the holding element is annular. A holding element of this type can be produced in a simple and low-cost manner.

The venting unit can have a cover for covering the filter element, wherein the cover has at least one inlet opening arranged in a side wall of the cover. The cover provides additional protection of the filter element from contamination and mechanical damage, while the gas exchange can take place via the at least one inlet opening in the side wall.

According to one exemplary arrangement, the housing and the holding element are shaped in such a way that a meandering venting channel is formed between the housing and the holding element. By virtue of the meandering shape of the venting channel, the flow path to the filter element is extended, making it less easy for dirt particles to reach the filter element.

DETAILED DESCRIPTION

The vehicle brake10comprises a brake caliper12, in which a space14for a brake rotor16is formed.

In addition, the vehicle brake10has an actuating piston18for a brake lining20, as can be seen in the sectional illustration inFIG.2.

The actuating piston18can be moved optionally between a retracted position and an extended position.

The actuating piston18is driven by an electric motor22(seeFIG.3).

Specifically, a drive torque generated by the electric motor22is transmitted to the actuating piston18and converted into a linear movement of the actuating piston18by a transmission unit24and a spindle drive26driven by the transmission unit24.

In the exemplary arrangement, the transmission unit24comprises a drive wheel28and a planetary transmission30, as can be seen inFIG.3. However, other exemplary arrangements are also conceivable.

The spindle drive26comprises a spindle32, which in the exemplary arrangement is designed as a ball screw spindle.

Furthermore, the vehicle brake10comprises a housing34.

The housing34is of multi-part design and comprises two housing shells38,40and a sleeve-shaped section42. However, a different division of the housing34is also conceivable.

With its end close to the brake rotor16, the housing34is fitted partially onto the brake caliper12.

Specifically, the sleeve-shaped section42of the housing34is fitted onto the brake caliper12and screwed thereto.

The housing34has a piston chamber44containing gas.

The piston chamber44accommodates the transmission unit24, the spindle drive26, and a control assembly46.

The actuating piston18is movably accommodated in the housing34, such that an end of the actuating piston18directed towards the brake lining20protrudes from the housing34, and an opposite end of the actuating piston18is accommodated in the housing34.

As can be seen inFIG.2, there is a seal48between the sleeve-shaped section42of the housing34and the brake caliper12.

There is likewise a seal50between the actuating piston18and the brake caliper12.

In one exemplary arrangement, the seal50is folded and can consequently unfold during a corresponding movement of the actuating piston18.

Thus, the gas-containing piston chamber44is sealed off from the outside at the interface between the housing34and the brake caliper12and in the region of the actuating piston18.

In order to enable a controlled pressure equalization or venting of the housing34, at least one venting unit52(seeFIGS.1and3) is accommodated in the housing. The venting unit52enables gas exchange between the piston chamber44and the environment.

In the exemplary arrangement illustrated inFIGS.1to3, the venting unit52is arranged in housing shell40.

Alternatively, the venting unit52can also be arranged in the further housing shell38, for example in its end wall or side wall, or in the sleeve-shaped section42.

In the exemplary arrangement according toFIGS.1to4, the housing34has an aperture53, wherein the venting unit52is accommodated in the aperture53.

Integrally formed on the housing34is a collar54, which surrounds the venting unit52and thus protects the venting unit52from damage.

The collar54is in the form of a circumferential rib.

The venting unit52can be seen in detail inFIG.4.

The venting unit52has a gas-permeable filter element56and a holding element58for the filter element56.

As an option, the venting unit52has a cover60for covering the filter element56.

The cover60has a plurality of inlet openings62arranged in a side wall of the cover60.

The cover60is firmly connected to the holding element58, for example latched, adhesively bonded or welded.

The venting unit52is fixed on the housing34by the holding element58.

In the exemplary arrangement according toFIG.4, latching elements64are integrally formed on the holding element58. The holding element58protrudes through the aperture53in the housing34and is latched to the housing34by the latching elements64.

Alternatively, a thread can be formed on the holding element58, thus enabling the venting unit52to be screwed into the housing34. As a further alternative, the holding element58can be adhesively bonded or welded to the housing34.

A seal66, for example, a sealing ring, is present between the venting unit52and the housing34, to be more precise between the holding element58and the housing34. This ensures that a gas exchange takes place exclusively via the filter element56.

Arranged in the holding element58is a plurality of venting channels68, which are covered by the filter element56.

Adjacent to the outlet openings of the venting channels68, a support surface70is formed, against which the filter element56rests, thereby limiting a deformation of the filter element.

The filter element56is formed from a hydrophobic and/or oleophobic material.

Moreover, the filter element56has a microporous structure.

For example, the filter element56consists of polytetrafluoroethylene, for example, of multi-directional expanded polytetrafluoroethylene.

In the exemplary arrangement illustrated inFIG.4, the filter element56is implemented as a membrane, that is, the filter element56has a large extent compared to its material thickness.

The filter element56is overmoulded along its outer edge with the material that forms the holding element58. Alternatively, it is conceivable for the filter element56to be adhesively bonded or welded to the holding element58.

FIG.5shows a venting unit52according to a further exemplary arrangement, which according to the disclosure can also be present in a vehicle brake10.

According to the exemplary arrangement illustrated inFIG.5, the holding element58is annular.

The profile of the annular holding element58is stepped, ensuring that the filter element56is not compressed too much during assembly.

The holding element58may be adhesively bonded or welded to the housing34, for example by ultrasonic welding or high-frequency welding. A gas-tight connection is thus achieved.

During welding, the material of the holding element58and/or of the housing34is melted and penetrates the porous structure of the filter element56, thereby ensuring that a reliable connection is achieved.

The filter element56is formed, for example, from the same material as the filter element56described in conjunction withFIG.4.

In order to simplify handling during assembly, the filter element56can be secured on the holding element58in the manner already described in conjunction withFIG.5, for example by injection moulding, adhesive bonding or welding.

It is also conceivable for the filter element56to be overmoulded along its outer edge with the material that forms the housing34.

In one exemplary arrangement, the venting unit52rests against an inner side of the housing34, thereby protecting the venting unit from mechanical damage. However, it is also conceivable in principle to arrange the venting unit52on the outside of the housing34.

In the region of the venting unit52, there is a plurality of apertures53in the housing34, wherein the venting unit52, to be more precise the filter element56, covers the apertures53.

By providing a plurality of apertures53, the support of the filter element56is optimized in this exemplary arrangement too.

FIG.6shows a venting unit52according to yet another exemplary arrangement, which according to the disclosure can also be present in a vehicle brake10.

For example,FIG.6illustrates two venting units52, wherein one of the two venting units52is identical to the venting unit52illustrated inFIG.5.

The further venting unit52comprises a holding element58which is shaped like a cover and covers the aperture53in the housing34.

In addition, the holding element58covers a further region of the housing34, wherein the housing34and the holding element58are shaped in such a way that a meandering venting channel72is formed between the housing34and the holding element58.

For example, the holding element58and the housing34have a corrugated region.

The venting channel72opens into the aperture53and into an opening74in the cover-shaped holding element58.

A filter element56is arranged, for example clamped, in the venting channel72, that is to say between the holding element58and the housing34.

In this case, the filter element56is accommodated in a form-fitting manner in the venting channel72, and therefore defined positioning of the filter element56is achieved.

In this case, the filter element56is cuboidal.

In a further alternative exemplary arrangement, only one of the two venting units52illustrated inFIG.6may be present.

An alignment element76in the form of an annular projection for aligning the cover-shaped holding element58is provided on the housing34.

The holding element58can be connected, for example, adhesively bonded or welded, to the housing34in a gas-tight manner along the alignment element76.