Throttle disk of a hydraulic assembly of a vehicle brake system

In a throttle disk of a dynamic throttle of a hydraulic assembly of a vehicle brake system, with at least one disk surface which is formed by a rigid material, a layer of elastic material is at least partially formed on the disk surface.

This application claims priority under 35 U.S.C. § 119 to application no. DE 10 2013 218 797.1, filed on Sep. 19, 2013 in Germany, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The disclosure relates to a throttle disk of a dynamic throttle of a hydraulic assembly of a vehicle brake system, with at least one disk surface which is formed by a rigid material. The disclosure relates, furthermore, to a use of such a throttle disk in a hydraulic assembly of a vehicle brake system.

Vehicle brake systems of modern motor vehicles, in particular of passenger cars, are equipped with externally controlled regulation of the brake pressure on associated wheel brakes. For this purpose, the vehicle brake systems have a hydraulic assembly in which, by means of pump elements, brake fluid can be conveyed under pressure to the wheel brakes or sucked away from these. The pump elements are configured as piston pumps, the pumping action of which pulses with the movement of the associated pump piston. In order to mitigate the resulting pulsation of the brake fluid stream, it is known to arrange a throttle disk in a fluid line of the vehicle brake system. The throttle disk can be deformed by the brake fluid stream and smoothing of the pressure profile in the fluid stream can thereby be achieved. For this purpose, the throttle disk is produced from comparatively rigid material, usually steel.

SUMMARY

According to the disclosure, a throttle disk of a dynamic throttle of a hydraulic assembly of a vehicle brake system is provided, with at least one disk surface which is formed by a rigid material and on which a layer of elastic material is at least partially formed.

The rigid material used is in this case, in particular, steel having a modulus of elasticity of between 180 000 and 220 000 N/mm2, especially preferably of 200 000 N/mm2.

By means of the throttle disk according to the disclosure, this has formed on it a surface portion on which is located not the rigid material affording the throttle action, but instead an elastic material which is considerably softer in comparison with this. The throttle disk according to the disclosure then bears with this material, in particular, against an adjacent component. Deformation and subsequent reverse deformation of the throttle disk according to the disclosure then gives rise to the situation where the throttle disk does not butt against the adjacent component with rigid hard material, but instead with soft elastic material. As a result, when the associated hydraulic assembly is in operation, less noise arises during the deformation and the reverse deformation of the throttle disk according to the disclosure than is the case in conventional throttle disks. Better noise characteristic values can therefore be achieved by means of the throttle disk according to the disclosure. Furthermore, with an appropriate configuration and placement, the throttle disk according to the disclosure has an increased sealing action, as a result of which the closing momentum intended by it can also be reduced. These functions of the throttle disk according to the disclosure also have an advantageous effect upon its throttling function and also upon its noise behavior. At the same time, the throttle disk according to the disclosure can be produced very cost-effectively and can be installed in the customary tried-and-tested way.

Preferably, in the throttle disk according to the disclosure, its disk surface is configured in the form of a ring with a first disk side and with an opposite second disk side, and the layer of elastic material is formed only at the radially outer margin of the first disk side. The throttle disk, as such, is therefore covered only partially with elastic material, specifically, in particular, only at its outer margin. As explained above, in its position of rest, the throttle disk can then be laid against an adjacent component at this outer margin. By means of its comparatively rigid material, it is deflected resiliently out of the position of rest on account of fluid pressure and subsequently moves back into the position of rest again, the elastic material then butting against the adjacent component and sealing off there.

Furthermore, advantageously, the layer of elastic material can also be formed at the radially outer margin of the second disk side. Such a layer, formed only in regions, of elastic material on the throttle disk according to the disclosure can be produced especially cost-effectively and affords the largely identical effect according to the disclosure, particularly when the throttle disk bears only at its outer margin against another component in order to fulfill its throttling function.

Alternatively, the throttle disk according to the disclosure is configured on its disk surface in the form of a ring with a first disk side and with an opposite second disk side, and the layer of elastic material is formed on the entire area of the first disk side. Preferably, the layer of elastic material is then also formed on the entire area of the second disk side.

The layer of elastic material according to the disclosure is preferably configured with ethylene-propylene-diene rubber (EPDM, ethylene-propylene-diene monomer). This material has a very good heat and cold behavior, has high ozone resistance and, furthermore, is resistant to aqueous chemicals.

Furthermore, according to the disclosure, an elastic material is especially preferably used which has a modulus of elasticity of 15 to 20 N/mm2, in particular of 17.5 N/mm2By means of such material, both the desired throttling action and the intended noise reduction can be optimally achieved.

The disclosure is also correspondingly aimed especially at a use of such a throttle disk according to the disclosure in a hydraulic assembly of a vehicle brake system.

In such a use, the throttle disk is preferably arranged downstream of an outlet valve of a pump element of the hydraulic assembly. The throttle disk is therefore located directly behind the outlet valve in the flow direction and provides the intended reduction in the pressure pulsation there directly behind the pump element along the flow path.

The throttle disk is in this case advantageously arranged in a flow duct of the hydraulic assembly such that it experiences the onflow on one of its disk sides and is deflected transversely to the disk side by the onflow. The throttle disk therefore experiences the onflow transversely to its plate-shaped extent. It consequently has a large onflow surface, upon which the onflowing pulsating fluid can act correspondingly. At the same time, the elastic material attached according to the disclosure to the disk side acts itself as a pulsation damper and, furthermore, reduces the noise behavior of the throttle disk during its deformation and when it butts against adjacent components.

Accordingly, it is especially preferred, according to the disclosure, that the throttle disk experiences the onflow on that disk side on which the layer of elastic material is located.

DETAILED DESCRIPTION

The figures illustrate a portion of a pump element10of a hydraulic assembly of a vehicle brake system. The pump element10is configured with a pump cylinder12, on the end-face cylinder bottom of which is located an outlet valve14. The outlet valve14is configured with a valve seat16which is formed in the cylinder bottom and which frames an annular valve port18.

The valve port18can be closed selectively by a spherical valve body20which is forced against the valve seat16by means of a valve spring22.

In the flow direction of a fluid flowing out through the outlet valve14, that is to say downstream of the valve port18, is located an outlet duct24which surrounds the valve body20and which leads to an annular throttle disk26. The throttle disk26has an essentially plate-shaped configuration, is made from a steel material and extends in a likewise annular throttle space28, into which the outflowing fluid flows through an onflow duct30on the left side with respect toFIG. 1.

The fluid in this case passes through the onflow duct30onto a first disk side32or end face of the throttle disk26, which consequently forms a disk surface, in particular an onflow side of the throttle disk26. The fluid then has to flow around the throttle disk26before it can flow on a second opposite disk side36, as a disk side or end face of the throttle disk26, on its outflow side through an outflow duct34and out of the throttle space28again on the right side with respect toFIG. 1.

The outflowing fluid, when it flows around, deflects the throttle disk26transversely to its disk plane in the direction of an arrow38, in particular, by virtue of its pulsating flow caused by the pump cylinder12. The throttle disk26is subsequently deformed back into its initial position again.

In this initial position, the throttle disk26bears with its first disk side32against a bearing edge40, so that a backing-up region is formed at this bearing edge40when the outflowing fluid flows onto it. The throttle disk26is therefore repeatedly lifted off briefly from the bearing edge40, is deformed into the outflow duct34on the second disk side36and then goes back onto the bearing edge40again.

In order, during this movement of the throttle disk26, to improve overall, in particular, its noise behavior at the bearing edge40and also its dynamic behavior, the throttle disk26is configured on at least one of its disk sides32or36with a layer42of elastic material. In the present case, the elastic material is EPDM which is applied in a layer thickness of between 0.2 mm and 0.6 mm, preferably 0.4 mm, to the otherwise as far as possible rigid steel material of the throttle disk26.

In the exemplary embodiment according toFIG. 2, the layer42of elastic material is applied only at a radially outer margin44of the annular throttle disk26.

In the exemplary embodiment according toFIG. 3, by contrast, the layer42of elastic material extends over the entire first disk side32or front side of the throttle disk26.

The rear side or second disk side36of the throttle disk26is also advantageously coated with elastic material at the margin44or over the entire area. By means of such a configuration, the resilient behavior of the throttle disk26when it is deflected in the throttle space28away from the bearing edge40and back to this bearing edge40can be further improved.

Furthermore, the elastic coating on the otherwise comparatively rigid throttle disk26improves its sealing action at the bearing edge40. The closing momentums of the throttle disk26are reduced, thus leading, in particular, to an improvement in its noise behavior.

Moreover, a coating of elastic material on the throttle disk26over the area of the latter improves the flow of outflowing fluid around it and reduces the occurrence of turbulences on its surface. The flow of the outflowing fluid is consequently smoothed out further and pulsations can be additionally avoided.