Brake system with parking brake

Abstract

The invention relates to a brake system comprising a parking brake having an axially movable piston (10) which can be acted upon by a pressure medium and which is operatively connected to a brake lining (2), in particular a brake shoe, said brake system being designed such that the piston (10) acts on a spring system (4) which is connected to the brake lining (2).

Description

Technical Field

[0001] The invention relates to a brake system with a parking brake according to the preamble of claim 1 . Background Art

[0002] Such a brake system is known from US Pat. No. 9,623,855 B2, which is used in particular in rail vehicles.

[0003] The parking brake described therein is designed in such a way that a piston locks the service brake in the parking position.

[0004] Compared to spring-energy brakes also known from the prior art, in which a spring generates the parking brake force, a locking piston is disadvantageous because the brake system as a whole is only elastic to a small extent, which leads to relatively large losses in braking force in the event of travel losses, for example due to cooling of the friction pair.

[0005] In brake systems with a brake caliper unit, this disadvantage does not occur substantially because, due primarily to the elasticity of the brake caliper lever, even in the case of a so-called normal travel loss, the force loss is low, at most 20%.

[0006] Force losses of this magnitude also occur in spring-energized parking brakes known from the prior art, which differ from the parking brake known from the aforementioned US Pat. No. 9,623,855 B2 but also from the parking brake known from EP 2,826,684 B1.

[0007] This is primarily because the spring loses some of its force over time and / or has relatively large tolerances, so that minimum values ​​must be taken into account when designing the spring.

[0008] In addition, the spring has a decreasing spring characteristic curve, that is, the force decreases as the stroke increases. Here, when designing the spring, the most unfavorable situation must always be considered.

[0009] In particular in the case of brake calipers or shoe brakes, a direct implementation of the parking brake system known from US Pat. No. 9,623,855 B2 is not possible, since the entire actuator / brake disc or actuator / wheel bearing / bogie system is so rigid that relative movements, such as occur when loading and unloading the vehicle, lead to large force losses. Summary of the invention

[0010] The object of the present invention is therefore to further develop a brake system of the generic type in order to realize a reliable parking brake in a structurally simple manner.

[0011] This object is achieved by a brake system having the features of claim 1 .

[0012] Thus a system was created which acts only as a parking brake without affecting the function of the service brakes.

[0013] As mentioned above, the rigidity of the force transmission components in certain types of actuators, such as brake calipers or shoe-type brake units, is so great that the brake system known from US 9623 855 B2 cannot be used. In contrast, the spring system according to the invention now creates a remedy. It should be particularly emphasized here that the invention can be realized with only a small outlay in design and manufacturing technology, which meets the requirements of the past.

[0014] The spring system, to which the axially movable piston is connected, can be formed by a preloaded spring assembly which is preloaded by means of the overpressure present during normal actuation of the service brake, thereby producing additional elasticity in the force flow.

[0015] The spring system is designed in such a way that it provides a sufficient travel and does not fall below a minimum parking brake force.

[0016] The spring system can be designed structurally in such a way that a compression spring, preferably a helical spring, is positioned in a telescopic housing, wherein a first housing section (the compression spring is supported on the bottom of the first housing section) is connected to a brake lining, in particular a brake shoe, and another second housing section (the compression spring rests with its other end on the bottom of the second housing section) can be moved relative to the first housing section by means of a piston, thereby tensioning the compression spring.

[0017] A piston acting on the second housing portion is supported in a cylinder, and the piston surface can be acted upon by a pressure medium, in particular compressed air, but also by a pressurized fluid.

[0018] In principle, the spring system can also be formed from one or more spring elements, for example as disc springs, which are arranged in series or in parallel as a spring group.

[0019] Further advantageous embodiments of the invention are characterized in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0021] The single FIGURE shows a schematic side view of a parking brake of a braking system according to the invention. DETAILED DESCRIPTION

[0022] It can be seen in the figure that for braking a wheel 1 , in particular a rail vehicle wheel, a brake lining 2 is provided which is designed as a shoe brake and can be pressed with a brake shoe 3 against the wheel 1 during braking.

[0023] When the wheel 1 or the rail vehicle is in the parking position, the parking brake acts on the brake lining 2 .

[0024] The parking brake has a piston 10 which is guided axially movably in a cylinder 9 , with a piston rod 11 and an end-side piston surface 12 which rests in the cylinder 9 in a sealing manner against the inner wall thereof.

[0025] A pressure medium, preferably compressed air or a pressure fluid, can be supplied via the connection 13 , with which pressure medium the piston surface 12 is acted upon.

[0026] At the end opposite the piston face 12 , the piston rod 11 acts on a spring system 4 which has a housing 5 in which a compression spring 6 in the form of a helical spring is arranged.

[0027] The housing 5 consists of a first housing section 7 and a second housing section 8 which is axially displaceable relative to the first housing section, wherein the two housing sections 7 , 8 are arranged telescopically relative to each other.

[0028] The first housing portion 7 is connected to the brake lining 2 , while the piston rod 11 acts on the second housing portion 8 .

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

[0030] During operation, pressure is built up on the piston 10 via the pressure medium against the piston surface 12 and the spring is tensioned by displacement of the second housing portion 8 , thereby pressing the brake lining 2 against the running surface of the wheel 1 .

[0031] Reference numerals list

[0032] 1 wheel

[0033] 2 brake linings

[0034] 3 brake shoes

[0035] 4 spring system

[0036] 5 Shell

[0037] 6Compression spring

[0038] 7 Shell section

[0039] 8 Shell section

[0040] 9 cylinders

[0041] 10 Piston

[0042] 11 Piston rod

[0043] 12 piston surface

[0044] 13 Connectors

Claims

1. A braking 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 lining (2), in particular a brake shoe, characterized in that: The piston (10) acts on a spring system (4) which is connected to the brake lining (2).

2. The braking system according to claim 1, characterized in that: The spring system (4) is arranged in a telescopically movable housing (5).

3. The braking system according to claim 1 or 2, characterized in that: The housing (5) comprises a first housing section (7) and a second housing section (8), which are axially movable relative to each other.

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 and 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).

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

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

8. Braking 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) bears sealingly against an 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 a pressure medium.

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