Braking system having a parking brake

Abstract

A braking system having a parking brake which comprises an axially movable piston (10) that can be pressurized by a pressure medium and that is operatively connected to a brake covering (2), in particular a brake pad, is designed in such a way that the piston (10) engages a spring system (4) that is connected to the brake covering (2).

Description

[0001] Braking system with a parking brake

[0002] DESCRIPTION

[0003] The invention relates to a braking system with a parking brake according to the preamble of claim 1.

[0004] Such a braking system, which is used in particular in a rail vehicle, is disclosed in US 9623 855 B2.

[0005] The parking brake described therein is designed in such a way that the piston blocks the service brake in the parking position.

[0006] Compared to a spring-loaded brake, which is also known from the prior art and in which a spring generates the parking brake force, a blockage of the piston is disadvantageous in that the braking system as a whole is only elastic to a small extent, which leads to relatively large losses of braking force in the event of stroke losses, e.g. due to cooling of the friction partners.

[0007] In braking systems with brake caliper units, this disadvantage does not arise because the elasticity of the caliper levers in particular means that the loss of power remains small, at most 20%, even with normal stroke losses.

[0008] A loss of power of this magnitude also occurs in the spring-loaded parking brakes known from the prior art, which differ from the parking brake known from US 9623 855 B2 mentioned at the beginning, but also from the parking brake known from EP 2826 684 B1.

[0009] This is mainly because the springs lose some of their force over time and / or have relatively large tolerances, so that minimum values ​​must be assumed when designing the springs.

[0010] Furthermore, springs have a decreasing spring characteristic, meaning that the force decreases with increasing stroke. Here, too, the worst-case scenario must always be considered when designing springs. Especially with brake calipers or block brakes, the direct implementation of the parking brake system known from US 9623 855 B2 is not possible, since the entire system of actuator / brake disc or actuator / wheel / wheel bearing / bogie is so rigid that relative movements, such as those that occur during loading and unloading of the vehicle, would lead to a significant loss of force.

[0011] The object of the invention is therefore to further develop a braking system according to the type in order to realize a reliable parking brake using structurally simple means.

[0012] This object is achieved by a braking system having the features of claim 1.

[0013] This creates a system that is used exclusively as a parking brake without affecting the function of the service brake.

[0014] As mentioned, the stiffness of the force-transmitting components in certain types of actuators, such as brake calipers or block brake units, is too great to allow the braking system known from US Pat. No. 9,623,855 B2 to be used. The spring system according to the invention now provides a remedy. It is particularly noteworthy that the invention can be implemented with minimal design and manufacturing effort, which meets a constant demand.

[0015] The spring system to which the axially movable piston is connected can be formed from a pre-tensioned spring group which is pre-tensioned by means of an overpressure occurring during normal service brake application, thereby creating additional elasticity in the force flow.

[0016] The spring system is designed to provide sufficient travel and ensure that a minimum parking brake force is not exceeded.

[0017] The spring system can be designed in such a way that a compression spring, preferably a helical spring, is positioned in a telescopic housing, wherein a first housing section, on the base of which the compression spring is supported, is connected to a brake pad, in particular a brake block, while another, second housing section, on the base of which the compression spring rests with its other end, is displaceable by means of the piston relative to the first housing section, whereby the compression spring is tensioned.

[0018] The piston engaging the second housing section is mounted in a cylinder, wherein a piston surface can be subjected to a pressure medium, in particular compressed air, but also to a pressure fluid.

[0019] In principle, the spring system can also be formed by one or more spring elements, for example as disc springs, which are arranged in series or parallel as a spring package.

[0020] Further advantageous embodiments of the invention are characterized in the subclaims.

[0021] An embodiment of the invention is described below with reference to the accompanying drawings.

[0022] The single figure shows a schematic side view of a parking brake of the braking system according to the invention.

[0023] In the figure it can be seen that in order to brake a wheel 1, in particular a rail vehicle wheel, a brake pad 2 is assigned, which is designed as a block brake and can be pressed against the wheel 1 with a brake block 3 in the event of braking.

[0024] A parking brake engages the brake pad 2 when wheel 1 or the rail vehicle takes up a parking position.

[0025] This parking brake has a piston 10 which is guided axially movable in a cylinder 9, with a piston rod 11 and an end-side piston surface 12 which lies tightly against the inner wall of the cylinder 9.

[0026] A pressure medium, preferably compressed air or a pressure fluid, can be supplied via a connection 13, with which the piston surface 12 is acted upon.

[0027] At the end opposite the piston surface 12, the piston rod 11 engages a spring system 4, which has a housing 5 in which a compression spring 6 in the form of a helical spring is arranged. The housing 5 consists of a first housing section 7 and a second housing section 8 that is axially displaceable relative thereto, with both housing sections 7, 8 being arranged telescopically relative to one another.

[0028] The first housing section 7 is connected to the brake pad 2, while the piston rod 11 engages the second housing section 8.

[0029] The compression spring 6 is supported with one end on the base of the first housing section 7 and with its other end region on the base of the second housing section 8.

[0030] When in operation, pressure is built up on the piston surface 12 by a pressure medium on the piston 10 and the spring is tensioned by moving the second housing section 8, while at the same time the brake pad 2 is pressed against the running surface of the wheel 1.

[0031] LIST OF REFERENCE SYMBOLS

[0032] 1 wheel

[0033] 2 brake pads

[0034] 3 brake pad

[0035] 4 spring system

[0036] 5 housings

[0037] 6 compression spring

[0038] 7 Housing section

[0039] 8 Housing section

[0040] 9 cylinders

[0041] 10 pistons

[0042] 11 Piston rod

[0043] 12 piston area

[0044] 13 Connection

Claims

Claims 1. Brake system with a parking brake having an axially movable piston (10) which can be acted upon by a pressure medium and is operatively connected to a brake pad (2), in particular a brake block, characterized in that the piston (10) acts on a spring system (4) which is connected to the brake pad (2).

2. Braking system according to claim 1, characterized in that the spring system (4) is arranged in a telescopically displaceable housing (5).

3. Braking system according to claim 1 or 2, characterized in that the housing (5) has a first housing section (7) and a second housing section (8) which are axially displaceable relative to one another.

4. Braking system according to one of the preceding claims, characterized in that a compression spring (6) is arranged in the housing (5).

5. Braking system according to one of the preceding claims, characterized in that the compression spring (6) is designed as a helical spring, with one end being supported on the base of the first housing section (7) and the other end region being supported on the base of the second housing section (8).

6. Brake system according to one of the preceding claims, characterized in that the first housing section 7 is connected to the brake pad (2).

7. Brake system according to one of the preceding claims, characterized in that the piston (10) has a piston rod (11) connected to the second housing section (8) and provided with a piston surface (12) at the other end.

8. Brake system according to one of the preceding claims, characterized in that the piston (10) is guided in a cylinder (9), wherein the piston surface (12) lies tightly against the inner wall of the cylinder (9).

9. Braking system according to one of the preceding claims, characterized in that the cylinder (9) has a connection (13) for the pressure medium.

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