Free-travel compensated friction pad reset device with residual braking torque avoidance for a motor vehicle wheel brake as well as motor vehicle wheel brake with free-travel compensated friction pad reset device

Abstract

The invention relates to a novel friction lining return device for a motor vehicle wheel brake, such as, in particular, a motor vehicle drum brake, comprising a rotationally fixed holder 1 for an actuating device, namely, in particular, a spreading device 4, which acts upon brake-actuated, displaceable, and rotationally fixed friction linings, namely, in particular, expandable brake shoes 2a, 2b, which cooperate with a brake rotor, namely, in particular, with a brake drum, and comprising at least one friction lining return device associated with a friction lining, which serves to return the lining from a brake actuation position to a brake readiness position, or to a return position, for the purpose of releasing the brake. The invention is based on the objective of eliminating deficiencies according to the prior art and thus offering an effectively and simply rationally improved and needs-based compensated return for a friction brake. The object is solved according to the invention by integrating an automatically self-adjusting adjusting means defined without current in each friction lining resetting device, in order to compensate for unsuitable, undesirable, or situationally excessive friction lining resetting, in particular as a result of friction wear, thermal effect, etc., and wherein the friction lining resetting device is clamped with a defined preload force between holder (1) and brake shoe (2a,b).

Description

[0001] The invention describes a further developed automatic friction pad resetting device for residual braking torque avoidance for a motor vehicle wheel brake, in particular with electromechanical brake-by-wire service brake actuator and a corresponding brake-by-wire (dry-by-wire) motor vehicle wheel brake which includes the idle-compensated improved friction pad resetting device.

[0002] The invention may, in principle, relate equally to an application in connection with dry-by-wire disc brakes as well as to an application in connection with dry-by-wire drum brakes. An exemplary and superior description of the proposed improvement is given below as a dry-by-wire application (electrically actuated brake) for a motor vehicle drum brake, as exemplified in the earlier application DE 10 2023 106 817.2 of the same applicant, and in this context, reference is made to the relevant technology of the electric drum brake with return springs for brake shoes 2a,b in conjunction with a special load measuring device.

[0003] Conventional hydraulically operated drum brakes typically include at least one spreading device between the ends of the brake shoes and two return springs that are elastically pre-tensioned and clamped between the two brake shoes. The line of force exerted by the elastically pre-tensioned return springs is generally parallel to the line of force exerted by the brake shoe spreading mechanism, specifically parallel to the spreading action of the (hydraulic) spreading device.

[0004] From EP 398 546 B1, a combined service and parking brake of the simplex drum brake type with primary and secondary brake shoes in fluidless dry-by-wire actuation is described, including a lever drive train and electromechanical actuation, wherein a telescopic adjusting device (strut) is inserted between the two brake shoes. Furthermore, an elastically pre-tensioned spring is clamped between the lever-actuated brake shoes, which pre-tensions the brake shoes towards each other. For the purpose of returning the brake shoes after brake application, it is described that each brake shoe has its own return spring. Each of the elastically clamped return springs is arranged transversely and acts on one side against one of the brake shoes and on the other side against the brake caliper (brake anchor plate).

[0005] The present invention aims to improve the following problems: Inertial and weight forces of brake shoes (A, B; or 2a, b) as well as inhibition, i.e., frictional forces of a brake shoe holder, are generally capable of preventing or inhibiting the desired brake shoe restoring effect. This inhibition can be promoted, for example, if elastically pre-tensioned (spring) holders / compression springs are provided to prevent rattling / fix the brake shoes A, B; 2a, b, and said retaining / compression springs are, for example, axially elastically pre-tensioned between the brake anchor plate and the brake shoe. This inhibition reduces the restoring effect because it opposes the return of the brake shoes / lining carriers and is therefore the cause of incomplete release of the linings from the drum, which can subsequently lead to undesirable residual braking torque (undesired dragging brake).

[0006] Elastically clamped springs between brake shoes A and B can lead to fault conditions if they are misaligned, if, on the one hand, a rubbing contact of one brake shoe (A) is prevented, but, due to misalignment, gravity, or similar reasons, the other lining (B) unintentionally contacts the brake drum and thereby generates residual braking torque.

[0007] Against this background, the present invention proposes at least one additional restoring measure, as can be seen in the drawing. The additional measure can, in particular, be in the form of an additional restoring device, which may preferably be designed as an elastic element, and especially preferably as one or more special springs. The additional measure can be embodied with several special springs (see in particular the drawing). Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6) are present.

[0008] An additionally defined return mechanism according to the invention may, in particular preferably, have at least one further integrally incorporated elasticity, and in the particularly preferred embodiment, may also be designed as a special spring (special spring mechanism). Particularly preferably, a special spring engages radially between the brake holder and a brake shoe, as can be seen from the figure. If the aforementioned additional measure is implemented as shown in Fig. In a particularly advantageous embodiment, a centering measure is made possible by the fact that 1 - 6 are arranged in pairs and diametrically opposite each other.

[0009] The intended beneficial effect of the described additional device / special measure / special spring mechanism is as follows: The force flow, or arrangement of additional elasticity / special spring, is achieved, on the one hand, with a fixed connection / support to a brake carrier / brake anchor plate / drum brake backing plate, such that each brake shoe or lining carrier receives a (radially inward-directed) force vector for basic elastic distancing. This force vector serves the purpose of removing each brake shoe from the frictional engagement of the brake drum in the brake release direction. The separate, i.e., individualized, return action is intended to prevent any feedback effect on the positioning of another friction lining / brake shoe. This function applies equally to all wear conditions of the wheel brake system.The individually tailored measure implemented according to the invention effectively prevents undesirable feedback to an adjacent friction lining. Undesirable offset, lateral interference, or transfer, such that the resetting of one friction lining could cause a neighboring friction lining to come into undesirable contact, is avoided according to the invention. Advantageously, the resetting path of the special resetting mechanism is limited to the path of the clearance range. In the particularly advantageous variant presented, with the special measure arranged in pairs diametrically opposed to each other, optimal centering of all brake shoes in relation to the brake drum is achieved. This advantageous effect can thus help to prevent uneven friction lining wear.

[0010] The following explanation of further details of the invention relates in particular primarily to the Fig. 7 - 9 in conjunction with functional elements of special spring mechanisms: In order to overcome fundamentally prevailing "disturbance", i.e., parasitic forces or influences (gravitational force, frictional force), a preferred restoring device has an automatic current-free limitation. This can be embodied, for example, by the limitation being represented by a restrained elasticity, such as, in particular, by a restrained spring, which in turn imposes a defined limited restoring force that is suitable and intended to limit the restoring force imparted to the respective brake shoe over the entire operating air gap range sair as well as over the entire operating pad wear range Spad wear and actuation range sactuation. Fig. 8) to limit between a maximum force effect Fmax_Reverse and a minimum force effect Fmin_Reverse. Changes resulting from the wear of the friction partners (drum and lining wear) can preferably be compensated by a self-adjusting plastic element on which the restrained spring may rest and which, during the actuation process, is directly or indirectly (e.g., via the spring) plastically pressed against the back plate by the moving lining carrier.

[0011] It is understood that an additional device according to the invention, such as the advantageously described elasticity, namely that one or more springs in system operation can be designed to be at least partially elastic and / or at least partially plastically deformable at least over certain wear conditions, so that independent automatic compensation is enabled.

[0012] In further explanation based on Fig. 10+ Fig. 11. It should be noted that the design and construction of an additional return mechanism can, in principle, be represented in many different ways. In an alternative embodiment, it is particularly conceivable, for example, that a plastically effective (travel) compensation is designed to be reversible and / or irreversible. As an example of irreversible plastic deformation, a plastically compliant component, such as a plastically deformable spring (section), can be given. Reversible plastic deformation has the advantage that components can be reused. Such a reversible design can, for example, be based on the model of a slip clutch, in that at least two components are mounted so that they can be moved relative to each other, and in which a force-fit connection, such as a clamping connection, ratchet connection, or similar, exists between the at least two components.is present, and the automatic compensation task may be formulated on the basis of the fundamentally relatively displaceable arrangement of the parts or components (cf. . Fig. 10 - 13). Reference symbol list 1 backplate 2a First brake shoe 2b Second brake shoe 3 Adjustment unit 4 Spreading device 5 WCU (Wheel Control Unit = wheel brake electronics with or without electromechanical actuator) 7 Load measuring device QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2023 106 817.2

[0002] EP 398 546 B1

[0004]

Claims

[1] Friction lining resetting device for a motor vehicle wheel brake, such as in particular a motor vehicle disc brake or motor vehicle drum brake, comprising a brake rotor, such as in particular a brake drum, comprising a rotationally fixed holder (1), comprising at least one rotationally fixed actuating device for the purpose of brake actuation, in particular in the configuration of an electrical spreading device (4), which, via preferably one or more translationally adjustable actuating elements, displaces brake-actuable and rotationally fixed brake shoes (2a, 2b) in a brake actuation direction for the purpose of frictional braking engagement with the brake rotor, or displaces them in an opposite direction for the purpose of brake release, and wherein the friction lining resetting device is suitable and intended to automatically reset at least one brake shoe (2a, 2b) in the opposite direction to its brake actuation direction without current, characterized byin that the friction lining resetting device imposes on the brake shoe (2a, 2b) an automatically wear-compensated braking readiness position by providing an automatic compensation means for frictional wear which avoids inappropriate, misplaced or excessive friction lining resetting and at the same time enables an automatic reduction of the free travel by clamping the friction lining resetting device between the holder (1) and the brake shoe (2a, b) in a defined manner as a function of a degree of frictional wear. [2] Friction lining return device or motor vehicle wheel brake according to claim 1, characterized by that the compensated friction lining return device comprises one or more elasticities, such as in particular one or more prestressed spring means. [3] Friction lining return device or motor vehicle wheel brake according to claim 1 and 2, characterized bythat a preload force and / or a preload path of the elasticity(ies), such as in particular of the spring means, is provided so as to be variable depending on the frictional wear path. [4] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that each brake shoe (2a,2b) is / are assigned at least one or more friction lining return devices, in particular exclusively. [5] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized bythat a brake shoe cooperates with several friction lining return devices, which are spaced apart from one another and offset from one another in angle, such that competing lines of action of the friction lining return devices are each aligned radially with respect to a wheel rotation axis Ax in a motor vehicle wheel brake, and further preferably radially, oriented towards the rotation axis. [6] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that competing lines of action, viewed in axial projection, intersect each other within the friction radius of a brake drum. [7] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized bythat one or more adjustment means is / are assigned to one or more return means for the purpose of brake wear compensation. [8] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that an adjustment device for brake wear compensation is designed to be flexible. [9] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that an adjusting means is designed to be deformable, in particular reversibly deformable. [10] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that an adjusting means is designed to be irreversibly deformable. [11] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that an adjusting device is inserted between a brake shoe and a bearing. [12] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that each adjusting means is adjustable depending on the brake wear path, in particular plastically deformable or telescopic, in order to compensate for component wear of brake wear parts. [13] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that the adjustment means is designed as an assembly component that can be handled independently, and / or assembled independently, and / or replaced independently as a wearing part. [14] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that the adjustment means and / or the automatic compensation means is / are designed as a module. [15] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that an adjusting means and / or compensation means is formed in one piece. [16] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that an adjusting means is constructed from two or more components which are held so as to be relatively displaceable and / or movable in relation to one another, such as in particular integrally telescopic. [17] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized bythat an adjusting means has at least one fixing means with a defined fixing force, such as, in particular, for example, a magnetic means, such as, in particular, for example, a retaining clip, such as, in particular, for example, a spring means, namely, in particular, for example, a spring clip. [18] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that an adjusting device is clamped telescopically between a bearing and a brake shoe. [19] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized bythat a safety device is assigned to an adjustment device which is suitable and intended, for example, to carry out an adjustment requested as being of an incorrect size in a limited manner as required, or to prevent an adjustment which is recognised as being requested incorrectly. [20] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized by that a securing device is mechanically designed. [21] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims 19, 20, characterized by that a safety device is designed as a thermal fuse. [22] Friction lining return device or motor vehicle wheel brake according to one or more of the preceding claims, characterized bythat an adjusting means and / or a securing means is formed with a bimetallic component, such as, in particular, for example, with a bimetallic spring, which is preferably designed as an elastically prestressed bimetallic spring clip. [23] Motor vehicle wheel brake with at least one friction lining return device, characterized by that the friction lining return device is designed according to at least one or more of the preceding claims 1-22.

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