Automatic compensator component for a motor vehicle drum brake, and motor vehicle drum brake comprising an automatic compensator component

Abstract

The present invention relates to automatic compensation by means of an automatic compensator component for a motor vehicle drum brake, and also to a motor vehicle drum brake comprising the automatic compensator component. A drum brake having a spreading device, in an exemplary embodiment in the form of an electric parking brake actuator (11), comprises a deformation section (18) arranged in a coupling rod (15). The coupling rod (15) transmits a force from the spreading device / parking brake actuator (11) to a brake shoe (2, 3). The deformation section (18) allows a deformation travel (x) to an extent which is restricted to a predetermined degree of wear and tolerance compensation. As a result, the drum brake has a particularly simple design and avoids unwanted noise.

Description

[0001] Description

[0002] Automatic compensator component for a motor vehicle drum brake and a motor vehicle drum brake with automatic compensator component

[0003] The invention relates to an automatic compensator suitable and intended for placement between brake shoes of a motor vehicle drum brake, and a motor vehicle drum brake with the compensator comprising a brake drum rotatably mounted relative to a support plate, two brake shoes arranged on the support plate, a spreading device for preloading the brake shoes against the brake drum, and a coupling rod arranged in the force flow between the parking brake actuator and at least one of the brake shoes. The drum brake preferably comprises an electric spreading device in the form of a motor-gearbox unit, such as, in particular, an electric parking brake actuator with an electric parking brake function that can be locked without current.

[0004] A drum brake is known, for example, from EP 2 670 997 B1. In this drum brake, a lever actuated by a cable is designed with a defined elasticity. The lever is connected to an actuating cable on one side and to a brake shoe on the other, with the lever having a predetermined spring characteristic. If the drum brake performs a parking brake function while hot and the brake drum subsequently cools down, the defined elastic compliance prevents jamming or destruction of the drum brake.

[0005] A drum brake with a coupling rod is known, for example, from WO 2015 / 101486 A1. In this drum brake, the coupling rod has bearings on a parking brake lever and one of the brake shoes. However, these bearings make the drum brake very complex.

[0006] Drum brake shoes are held in a rearward release position by return springs without activation, and an automatically telescoping strut / coupling rod serves to adjust the spacing. However, temperature fluctuations can cause play in transmission elements due to thermal expansion effects. Drum brake friction components (brake drums, brake shoes) are naturally subject to gradual wear of the friction partners, and another source of play can be manufacturing tolerances or installation tolerances of the cooperating components. Wear and installation tolerances can prevent the strut / coupling rod from functioning smoothly. Play between the strut / coupling rod and adjacent components can lead to further wear or annoying rattling noises.

[0007] The invention is based on the problem of developing an automatic compensator component or the relevant drum brake of the type mentioned at the beginning in such a way that it can help to avoid disturbing effects and is also particularly simple in design.

[0008] This problem is solved according to the invention. The invention extends equally to a compensator component, which may be provided as a self-contained, modular, and possibly pre-assembled component, as well as to the entirety of a correspondingly completed vehicle drum brake, which will be explained by way of example in the description based on the drawing.

[0009] The proposed solution is presented in such a way that the compensator component according to the invention enables, for the first time, currentless compensation in the case of elastic preload between brake shoes based on a predetermined, special, i.e., integrally arranged, degree of compliance / elasticity. This compliance is, for the first time, very specifically defined, as it is particularly well-balanced with the preload or spring stiffness of opposing brake shoe return springs.

[0010] The object is therefore excellently achieved by means of a deformation section with a prestressed elasticity / compliance, for example as a defined compensating spring component such that when the brake / parking brake is released, the deformation section / compliance is designed for the elastic prestressing of a strut / coupling rod on adjacent components of the drum brake and that a deformation path of the deformation section is limited to an intended wear and tolerance compensation of the components of the drum brake.

[0011] The arrangement with the integral elasticity of the compensator components can be defined in such a way that the coupling rod / strut elastically clamped between brake shoes, at least in a released state of a motor vehicle drum brake, is in an elastically prestressed force equilibrium with opposite elastically prestressed imposed return spring force (6,7).

[0012] Due to the preferred embodiment of the invention, the deformation section compensates for any possible play with adjacent brake shoes and the spreading device or electric parking brake actuator. However, during service braking, as well as when the parking brake is applied, the automatic limitation of the deformation path ensures reliable power transmission via the strut / coupling rod, because after the deformation path has been limited, the coupling rod according to the invention can function similarly to a rigid coupling rod / strut. The elasticity, in particular the spring force of the elasticity / compensating spring, is advantageously dimensioned such that it is strong enough to reliably position the ends of the coupling rod relative to adjacent areas of the drum brake in force equilibrium with return springs. Thanks to the invention, the deformation section prevents rattling of the coupling rod when the parking brake actuator is inactive.

[0013] According to another advantageous development of the invention, the coupling rod is particularly simply constructed if the coupling rod has, in line with the deformation section, a further section with high rigidity for supporting the brake shoe when the parking brake actuator is activated. Furthermore, the further section can have a length intended for use in the drum brake. The further section can be rigid or have a spring-loaded design.

[0014] According to another advantageous development of the invention, the necessary deformation path can be easily estimated if the deformation path corresponds to the path of the brake shoe over the wear of a friction lining plus a safety margin. Such a deformation path can be 4 to 6 mm for drum brakes for passenger cars, plus a safety margin.

[0015] According to another advantageous development of the invention, the coupling rod is designed to be particularly simple in terms of construction if the deformation section of the coupling rod has a cylinder and a piston that can be moved longitudinally therein, and if the piston is supported in the cylinder via the compensating spring. Furthermore, this allows the coupling rod to be manufactured as a preassembled component.

[0016] According to another advantageous development of the invention, it contributes to further simplifying the design of the drum brake if the piston and cylinder have stops opposite one another and if, in an unloaded basic position of the coupling rod, the distance between the stops corresponds to the intended deformation path.

[0017] Coupling rods of today's drum brakes are rigid in one embodiment, or they have a spring brake in another embodiment. According to another advantageous development of the invention, the drum brake embodiment featuring the spring brake enables a play-free arrangement of the coupling rod if a spring of a spring brake is arranged in the further section of the coupling rod and if the compensating spring has a lower spring force than the spring of the spring brake. This design ensures that the spring of the spring brake is only loaded when the deformation path of the second section is limited, for example, by the stops meeting.

[0018] Return springs in drum brakes are generally used to keep the brake shoe spaced from the brake drum when the actuators are inactive. According to another advantageous embodiment of the invention, disruption of the return spring's function due to the deformation section can be easily avoided if the compensating spring has a lower spring force than a return spring that retracts the brake shoe supported by the coupling rod to its home position. According to another advantageous embodiment of the invention, complex mounting of the coupling rod on the adjacent component can be easily avoided if the coupling rod and an adjacent component have support elements that axially bear against one another.

[0019] The invention permits numerous embodiments. To further clarify its basic principle, two of them are shown in the drawing and are described below. This shows in

[0020] Fig.1 shows a perspective view of a part of a drum brake,

[0021] Fig.2 schematically shows a first embodiment of a coupling rod of the drum brake from Figure 1 in partial section,

[0022] Fig.3 schematically shows another embodiment of a coupling rod from Figure 1.

[0023] Figure 1 shows a portion of a drum brake of a motor vehicle with a support plate 1 and brake shoes 2, 3 with friction linings 4, 5 supported on the support plate 1. For simplicity, a brake drum enclosing the brake shoes is only partially shown in the drawing in dash-dotted lines, with its contour opposite the brake shoes. In the assembled state, the brake drum is connected to a wheel (not shown), and the support plate 1 is connected to a body of the motor vehicle (likewise not shown). Two return springs 6, 7 bias the brake shoes 2, 3 against each other and thus away from the brake drum. The drum brake has a brake actuator 8 designed as a wheel brake cylinder as a spreading device for a service brake. An adjustment unit 9 is arranged parallel to the brake actuator 8. The ends of the brake shoes 2, 3 facing away from the brake actuator 8 are supported on a support bearing 10.

[0024] The drum brake also has a parking brake actuator 11. The parking brake actuator 11 is connected to a parking brake lever 13 via a parking brake actuator cable 12. The parking brake lever 13 is pivotally mounted about a bearing 14 and is supported on one of the brake shoes 2 via a coupling rod 15. Figure 2 shows a schematic partial section of the coupling rod 15 from Figure 1. The coupling rod 15 has support elements 16, 17 at its ends that axially support the parking brake lever 13 and one of the brake shoes 2. The coupling rod 15 has a deformation section 18 and a further section 19 that is very rigid compared to the deformation section 18. The further section 19 is rigid in this embodiment. The deformation section 18 has a piston 21 which can be moved into a cylinder 20 and a compensating spring 22 which supports the piston 21 in the cylinder 20.The coupling rod 15 also has opposing stops 23, 24, which limit the possible deformation by the deformation section 18 to a deformation path X. The compensating spring 22 has a lower spring stiffness than the return springs 6, 7 of Figure 1.

[0025] Figure 3 shows a further embodiment of a coupling rod 115, which differs from that of Figure 2 only in that a spring-loaded actuator 125 with a spring 126 preloaded with a defined force is arranged in a further section 119. The function of the spring-loaded actuator 125 comes into play when the parking brake actuator 111 is activated, when the drum brake cools down, or when the parking brake torque is reversed. If the force in the coupling rod 115 increases beyond the preload force of the spring 126, the length of the coupling rod 115 is reduced.

[0026] A deformation section 118 with a compensating spring 122 is arranged in a row with the further section 119. The compensating spring 122 has a lower stiffness than the spring 126 in the spring accumulator 125, so that here too the compensating spring 122 preloads the ends of the coupling rod 115 against adjacent components of the drum brake. As in the embodiment according to Figure 2, the deformation section 118 has two stops 123, 124 arranged at a distance from one another in an unloaded basic position with a deformation path X, which limit the possible deformation of the deformation section 118. List of reference symbols

[0027] Support plate

[0028] 2, 3 brake shoes

[0029] 4, 5 Friction lining

[0030] 6, 7 Return spring

[0031] 8 Brake actuator

[0032] 9 Adjustment unit

[0033] 10 support bearings

[0034] 11 Parking brake actuator

[0035] 12 Parking brake actuator cable

[0036] 13 Parking brake lever

[0037] 14 Storage

[0038] 15, 115 coupling rods

[0039] 16, 17 Support element

[0040] 18, 118 deformation section

[0041] 19, 119 Section

[0042] 20 cylinders

[0043] 21 pistons

[0044] 22, 122 compensating spring

[0045] 23, 24, 123, 124 stop

[0046] 125 spring accumulators

[0047] 126 spring

[0048] X Deformation path

Claims

Patent claims 1. Automatic compensator component for a motor vehicle drum brake, which is preferably formed as a multi-piece and telescopic coupling rod or strut, characterized in that the compensator component, namely in particular the coupling rod (15, 115), has a defined elasticity, which is in particular exemplary structurally present as a flexible deformation section (18, 118), so that an elastically prestressable compliance is defined such that its structurally predetermined deformation path (x) is limited on the basis of a structurally predetermined defined wear dimension range and / or tolerance dimension range during operational cooperation of the components of the motor vehicle drum brake.

2. Automatic compensator component according to claim 1, characterized in that the structurally predetermined deformation path (x) of the deformation section (18, 118) is limited to the wear dimension range and / or tolerance dimension range of the drum brake.

3. Automatic compensator components according to one or more of the preceding claims, characterized in that the elasticity of the compensator component is defined such that an elastically clamped coupling rod / strut, at least in a released state of a motor vehicle drum brake, is in a force equilibrium with a permanently impressed return spring force (6, 7) when elastically clamped.

4. Automatic compensator component for a motor vehicle drum brake, according to one or more of the preceding claims, characterized in that the coupling rod (15, 115) defines with the deformation section (x), preferably in alignment / in series on one axis, a further section (19, 119), preferably comprising a fixed stop, which is fixed or with an increased rigidity relative to the deformation section (x), namely in particular quasi-rigid, for the purpose of firmly supporting the brake shoe (2, 3) when the brake is actuated, such as in particular when the parking brake actuator (11) is actuated.

5. Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized in that the deformation path (x) corresponds to the path of the brake shoe (2, 3) via the wear of a friction lining (4, 5) plus a safety margin.

6. Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized in that the deformation section (18, 118) of the coupling rod (15, 115) comprises a cylinder (20) and a piston (21) which is longitudinally displaceable therein and that the piston (21 ) is supported in the cylinder (20) via the compensating spring (22, 122).

7. Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized in that the piston (21) and cylinder (20) have stops (23, 24, 123, 124) facing one another and that in an unloaded basic position of the coupling rod (15, 115) the distance between the stops (23, 24, 123, 124) corresponds to the intended deformation path (X).

8. Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized in that a spring (126) of a spring accumulator (125) is arranged in the further section (119) of the coupling rod (115) and that the compensating spring (122) has a lower spring force than the spring (126) of the spring accumulator (125).

9. Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized in that the compensating spring (22, 122) has a lower spring force than a return spring (6, 7) which retracts the brake shoe (2, 3) supported by the coupling rod (15, 115) into the basic position.

10. Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized in that the coupling rod (15, 115) and an adjacent component have support elements (16, 17) which axially support one another.

11. Motor vehicle drum brake with a brake drum arranged rotatably relative to a support plate (1), with two brake shoes (2, 3) arranged on the support plate (1), with a spreading device for displacing and / or bracing the brake shoes (2, 3) against the brake drum and with a strut / coupling rod (15, 115) arranged in the force flow between the spreading device and at least one of the brake shoes, wherein preferably an electrically actuated brake actuator is present, which is preferably formed as an electric motor-gearbox unit, such as in particular as an electric parking brake actuator with a current-free lockable electric parking brake function, and comprising an automatic compensator component, in particular according to one or more of the preceding claims 1-10, characterized in that the coupling rod (15, 115) has a deformation section (18, 118) with an elastically prestressed compensating spring (22,122) has that when the parking brake actuator (11) is inactive, the deformation section (18, 118) is designed to preload the ends of the coupling rod (15, 115) against adjacent components of the drum brake and that a deformation path (x) of the deformation section (18, 118) is limited to an intended wear and tolerance compensation of the components of the drum brake., 12. Motor vehicle drum brake according to claim 11, characterized in that the coupling rod (15, 115) with the deformation section (x) has in a row a further section (19, 119) with a high rigidity for supporting the brake shoe (2, 3) when the parking brake actuator (11) is activated.

13. Motor vehicle drum brake according to one or more of the preceding claims, characterized in that the deformation path (x) corresponds to the path of the brake shoe (2, 3) via the wear of a friction lining (4, 5) plus a safety margin.

14. Motor vehicle drum brake according to one or more of the preceding Claims, characterized in that the Deformation section (18, 118) of the coupling rod (15, 115) a cylinder (20) and a piston (21) which is longitudinally displaceable therein and in that the piston (21) is supported in the cylinder (20) via the compensating spring (22, 122).

15. Motor vehicle drum brake according to one or more of the preceding claims, characterized in that the piston (21) and cylinder (20) have stops (23, 24, 123, 124) opposite one another and that in an unloaded basic position of the coupling rod (15, 115) the distance between the stops (23, 24, 123, 124) corresponds to the intended deformation path (X).

16. Motor vehicle drum brake according to one or more of the preceding claims, characterized in that a spring (126) of a spring accumulator (125) is arranged in the further section (119) of the coupling rod (115) and that the compensating spring (122) has a lower spring force than the spring (126) of the spring accumulator (125).

17. Motor vehicle drum brake according to one or more of the preceding claims, characterized in that the compensating spring (22, 122) has a lower spring force than a return spring (6, 7) which retracts the brake shoe (2, 3) supported by the coupling rod (15, 115) into the basic position.

18. Motor vehicle drum brake according to one or more of the preceding claims, characterized in that the coupling rod (15, 115) and an adjacent component have support elements (16, 17) which axially support one another.

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