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CN-122029368-A - Drum brake

CN122029368ACN 122029368 ACN122029368 ACN 122029368ACN-122029368-A

Abstract

The invention relates to a drum brake (1), in particular for a utility vehicle, comprising a brake drum (2) rotatably mounted about a rotational Axis (AR), at least two brake linings (3) mounted in a receiving space (22) of the brake drum (2), having a respective friction lining carrier (32) and a friction lining (31) arranged thereon, and comprising a pressing device arranged rotationally fixed on an anchor housing (6), comprising a wedge ring (5) which can be moved on a cylinder liner (61) of the anchor housing (6) parallel to the rotational Axis (AR) of the brake drum (2) and by means of which the brake linings (3) can be pressed onto a housing inner surface (21) of the brake drum (2) in the form of a friction surface, which is embodied radially to the rotational Axis (AR) of the brake drum (2) via a respective pressure plunger (34), wherein the pressure plunger (34) is arranged around the rotational Axis (AR) of the brake drum (2), such that a first angular distance (W 12 ) from a radial axis (T r2 ) of a first pressure plunger (34) among the pressure plungers to a radial axis (T r1 ) of a second pressure plunger (34) adjacent in the circumferential direction (U) is not equal to a second angular distance (W 23 ) to a radial axis (T r3 ) of the pressure plunger (34) adjacent against the circumferential direction (U), wherein a ratio of a smaller angular distance (W 12 ) to a larger angular distance (W 23 ) of the angular distances does not exceed a limit value of 0.8 and does not exceed a limit value of 0.6.

Inventors

  • R. WEBER
  • J. Iresco
  • A. Buch
  • A. Hassani
  • C. Steger
  • A. Jishashi
  • F. Sheropf

Assignees

  • 克诺尔商用车制动系统有限公司

Dates

Publication Date
20260512
Application Date
20241021
Priority Date
20231107

Claims (6)

  1. 1. Drum brake (1) for a commercial vehicle, having: a brake drum (2) rotatably supported about a rotation Axis (AR), The number (N W ) of brake linings (3) mounted in the receiving space (22) of the brake drum (2) is at least two, said brake linings having a respective friction lining carrier (32) and a friction lining (31) arranged thereon, A pressing device which is arranged on the anchor housing (6) in a rotationally fixed manner and has a wedge ring (5) which can be displaced on a cylinder sleeve (61) of the anchor housing (6) parallel to the rotational Axis (AR) of the brake drum (2) and by means of which the brake linings (3) can be pressed via a respective pressure plunger (34) radially to the rotational Axis (AR) of the brake drum (2) onto a housing inner surface (21) of the brake drum (2) which is designed as a friction surface, It is characterized in that the method comprises the steps of, The pressure plungers (34) are arranged about the rotational Axis (AR) of the brake drum (2) such that a first angular distance (W 12 ) from a radial axis (T r2 ) of a first pressure plunger (34) of the pressure plungers to a radial axis (T r1 ) of a second pressure plunger (34) adjacent in the circumferential direction (U) is not equal to a second angular distance (W 23 ) from a radial axis (T r3 ) of a pressure plunger (34) adjacent in the opposite circumferential direction (U), The ratio of the smaller one (W 12 ) of the angular pitches to the larger one (W 23 ) of the angular pitches does not exceed a limit value of 0.8 and is not lower than a limit value of 0.6, And for the smaller of the angular pitches (W 12 ) apply: and for a larger angular interval (W 23 ) among the angular intervals: 。
  2. 2. Drum brake (1) according to claim 1, characterized in that the number (N W ) of brake linings (3) and pressure plungers (34) is four or six, wherein the pressure plungers (34) are arranged opposite each other in pairs with respect to the rotation Axis (AR).
  3. 3. Drum brake (1) according to claim 1 or 2, characterized in that the brake lining length (L) of the brake lining (3) as seen in the direction of rotation and the support height (H) as seen in the radial direction are dimensioned such that the quotient of the length (L) and the support height (H) is adapted: 。
  4. 4. A drum brake (1) according to claim 3, characterized in that the brake lining length (L) does not exceed 200 mm when the friction radius (R) of the brake drum (2) is 150 mm R < 175 mm, the brake lining length (L) does not exceed 240 mm when the friction radius (R) of the brake drum (2) is 175 mm R < 200 mm, and the brake lining length (L) does not exceed 280 mm when the friction radius (R) of the brake drum (2) is 200 mm R < 230 mm.
  5. 5. Drum brake (1) according to claim 4, characterized in that, A) When the friction radius (R) of the brake drum (2) is 150 mm≤R < 175 mm and the maximum brake lining length (L) is 200 mm, the quotient of length (L) and support height (H) applies: ; b) When the friction radius (R) of the brake drum (2) is 175 mm≤R < 200 mm and the maximum brake lining length (L) is 240 mm, the quotient of length (L) and support height (H) applies: ; c) And when the friction radius (R) of the brake drum (2) is 200 mm≤R < 230 mm and the maximum brake lining length (L) is 280 mm, the quotient of the length (L) and the support height (H) applies: 。
  6. 6. brake drum (1) according to any one of the preceding claims, characterized in that for a brake lining width (B) viewed in the direction of the rotation Axis (AR) in the mounted state: , wherein A Drum is defined as the free area of the brake drum (2) which does not contain its flange region (23).

Description

Drum brake Technical Field The present invention relates to a drum brake according to the preamble of claim 1. Background Drum brakes generally have a drum-shaped rotor on the inner side of which a friction surface is provided (also called brake drum). The braking force is generated by pressing the brake linings against the inner friction surface of the brake drum. According to the prior art, in drum brakes for utility vehicles, the actuating force introduced is usually increased by means of an S-cam in order to generate the required braking torque. In this case, two brake shoes which are rotatably mounted on one side are usually pressed against the inner wall of the brake drum by means of the eccentric action of the S-shaped cam with increased force. By using two brake shoes, the system is relatively stable with respect to its natural modes in terms of noise generation. In the drum brakes of the type described herein, the force transmission is designed such that the force introduced axially to the axis of rotation is increased by deflection thereof such that the reaction force acts radially on the friction surface of the brake drum, and the pressing of the brake linings is effected by means of wedges which can be displaced in the direction of the axis of rotation. The reaction force can be divided here by operating a plurality of pressure plungers. In terms of noise generation, the natural modes of the system are significantly more easily encountered in such drum brakes. This is mainly because the force introduction must take place mainly near the center of the brake lining and thus limits the possible extension of the brake lining in the circumferential direction. In such systems, therefore, at least three brake linings are often required in order to avoid overloading the system with respect to the pressure per unit area of the friction material and the thermal load. However, due to the large number of force introduction sites, the system is more unstable in terms of producing audible or perceptible vibrations (i.e., so-called NVH characteristics—noise, vibration, harshness). Disclosure of Invention The object of the present invention is to provide a drum brake of the same type with improved NVH characteristics. The object is achieved by a drum brake having the features of claim 1. A drum brake according to the invention, in particular for a utility vehicle, has a brake drum rotatably mounted about a rotational axis. The drum brake further has a number of at least two brake linings mounted in the receiving space of the brake drum, which have a respective lining carrier and a lining arranged thereon. The drum brake further has a pressing device, which is arranged on the anchor housing in a rotationally fixed manner and has a wedge ring, which can be displaced on the cylinder liner of the anchor housing parallel to the rotational axis of the brake drum, and by means of which the brake linings can be pressed radially to the rotational axis of the brake drum via the respective pressure ram onto the inner surface of the housing of the brake drum, which is designed as a friction surface. The pressure plungers are arranged around the rotational axis of the brake drum in such a way that a first angular distance from the radial movement axis of a first pressure plunger out of the pressure plungers to the radial movement axis of a second pressure plunger adjacent in the circumferential direction is not equal to a second angular distance from the radial movement axis of the pressure plunger adjacent in the opposite circumferential direction. The ratio of the smaller one of the angular distances (W 12) to the larger one of the angular distances (W 23) here does not exceed a limit value of 0.8 and is not below a limit value of 0.6. Here, for smaller angular distances among the angular distances, it is applicable: 。 For a larger angular interval among the angular intervals, it is applicable that: 。 where N W is the number of pressure plungers or brake pads. By arranging the brake linings in this way in the brake drum, the inherent modes of the system can be avoided, which results in a significantly reduced noise generation compared to the case when the brake linings are evenly distributed. In addition, micro-relative movements between the lining back plate of the brake lining and the anchor housing can thereby also be avoided. Advantageous embodiments of the invention are the subject of the dependent claims. According to an advantageous embodiment, the number of brake linings and pressure plungers is four or six, the pressure plungers being arranged opposite each other in pairs relative to the axis of rotation. By arranging the brake linings in pairs opposite each other, the forces exerted on the brake drum during braking can cancel each other out. According to a further advantageous embodiment, the brake lining length, viewed in the direction of rotation, and the brake lining support height, viewed in the radial direc