Showing papers on "Disc brake published in 2004"

Linear eigenvalue analysis of the disc-brake squeal problem

Abstract: This paper presents a numerical method to calculate the unstable frequencies of a car disc brake and suggests a suitable analysis procedure. The stationary components of the disc brake are modelled using finite elements and the disc as a thin plate. The separate treatments of the stationary components and the rotating disc facilitate the modelling of the disc brake squeal as a moving load problem. Some uncertain system parameters of the stationary components and the disc are tuned to fit experimental results. A linear, complex-valued, asymmetric eigenvalue formulation is derived for the friction-induced vibration of the disc brake. Predicted unstable frequencies are compared with experimentally established squeal frequencies of a real car disc brake. Copyright © 2004 John Wiley & Sons, Ltd.

Reduction of squeal noise from disc brake systems using constrained layer damping

Abstract: Squeal noise generation during braking is a complicated dynamic problem which automobile manufacturers have confronted for decades. Customer complaints result in significant yearly warranty costs. More importantly, customer dissatisfaction may result in rejection of certain brands of brake systems. In order to produce quality automobiles that can compete in today's marketplace, the occurrence of disc brake squeal noise must be reduced. The addition of a constrained layer material to brake pads is commonly utilized as a means of introducing additional damping to the brake system. Additional damping is one way to reduce vibration at resonance, and hence, squeal noise. The simulation of braking events in dynamometers has typically been the preferred insulator selection process. However, this method is costly, time consuming and often does not provide an insight into the mechanism of squeal noise generation. This work demonstrates the use of modal analysis techniques to select brake dampers for reducing braking squeal. The proposed methodology reduces significantly the insulator selection time and allows an optimized use of the brake dynamometer to validate selected insulators.

Two-/three-dimensional hybrid model of the thermomechanical behaviour of disc brakes

Abstract: Prediction of the surface temperature in friction braking systems is the main problem in the analysis of thermal dissipation and surface degradations such as wear, phase transformation, cracks, etc. The first difficulty of the thermal prediction is presented by the complex interactions between the thermal, mechanical and tribological behaviour. The second problem is due to the multiscale aspect, from the macroscopic response of the disc and brake pads (conduction, distortions, etc.) to local surface effects (surface roughness, wear debris, phase changes, etc.). This paper aims to propose a macrostructural model of the thermomechanical behaviour of the disc brake, taking into account the real three-dimensional geometry of the disc–pad couple. Contact surface variations, distortions and wear are taken into account. Real body geometry and thermoelastoplastic modelling of the disc material are specially introduced. Such a model aims to give predictions of the thermal gradients varying with time and of the thermomechanical response of the components. Predictions of the temperature distributions are compared with experimental measurements obtained by thermographs and thermocouples. Such a model seems to be a suitable base for the study of the thermal dissipation and the thermomechanical behaviour and for the introduction of local friction effects.

Control of an Electromechanical Brake for Automotive Brake-By-Wire Systems with an Adapted Motion Control Architecture

Abstract: A disk brake clamp force controller for electromechanical brakes (EMB) in automotive brake-by-wire systems may be obtained from a standard motion control architecture with cascaded position, speed and current control loops by replacing the outer position control loop with a force control loop. When implemented with proportional, integral and differential (PID) controllers this architecture generally performs well for standard motion control problems, but the EMB control problem is differentiated by a large operating range in which non-linear load disturbances such as friction become significant at high clamp forces of up to 30kN. This paper investigates the feasibility of a cascaded PI control architecture for an EMB with the intention of establishing a baseline standard against which the performance of future control schemes may be compared. Simulation results are presented based on an accepted EMB model.

Active Control of Brake Squeal Via “Smart Pads”

Abstract: Considerable effort is spent in the design and testing of disk brakes of modern passenger cars. This effort can be reduced if refined mathematical-mechanical models and new experimental techniques are used for studying the dynamics of these brakes. The present paper is devoted to the modeling and experimental investigation of a floating caliper disk brake, special regard being given to the suppression of squeal using active elements. To actively suppress brake squeal, smart pads were designed and manufactured. These pads contain piezoceramic staple actuators, which can be independently driven at both pads and within the pads. In experiments they were successfully used for the active suppression of squeal via optimal control. As the piezoceramic elements can be used both as actuators as well as sensors, the smart pads are also useful in experimental investigations such as measuring transfer functions. In this manner, design modifications proposed for conventional disk brakes can easily be tested using this method. Active control of squeal using smart pads is presently not envisaged as a technique to suppress squeal in mass produced disk brakes, but rather as a possible tool to be used in industrial laboratories to shorten the time for optimizing new brake designs, with high potential saving benefits. The development and laboratory implementation of the active squeal control goes along with a more profound understanding of brake squeal and a better modeling of the phenomena, ultimately leading to improvements in the design of disk brakes.

A disc brake

Abstract: A disc brake with self-servo effect comprises: a movable ramp plate (7) connected to a brake pad (2) for engagement with a brake disc (1), a ramp bridge (8), stationary in relation to the ramp plate, rollers (9) movable in ramps (7’, 8’) in surfaces facing each other of the ramp plate and the ramp bridge, and means (10-14) for imparting a control movement on the ramp plate. The arrangement is such that a movement of the ramp plate in the tangential direction of the brake disc will cause it to move towards or away from the brake disc. Slack adjusting means (27, 28) for compensating for the wear of the brake pad are arranged between the ramp plate and the brake pad.

Method of making brake discs and rotors with open slots and brake discs and rotors made therewith

Abstract: The present invention broadly comprises a brake disc having superior cooling characteristics and a method for manufacturing brake discs with superior cooling characteristics. The brake disc has at least one slot arranged at an angle greater than zero degrees and less than ninety degrees with respect to a radius of said disc passing through said slot. The angle can be selected to enhance cooling under specified conditions. Slots in the disc can open to an inner or outer perimeter of the disc or may be fully enclosed within the disc. The shape and width of the slots and the spacing between the slots can be selected to enhance cooling properties of the disc.

Manufacture of functionally graded carbon-carbon composites

Abstract: Annular brake disc preform (15), wherein 40 to 80 layers of reinforcement fibers of at least two different lengths (11, 19) ranging from 10-60 mm are distributed in a planar gradient throughout the body of the preform, with the reinforcement fibers located near the exterior planes of the disc being predominately shorter fibers (11) and with the reinforcement fibers located in the central planes of the disc being predominately longer fibers (19) Also, process of making carbon-carbon composite preforms by: providing chopped pitch or PAN fibers (11, 19) of at least two different lengths; directing a robotic spraying apparatus to spray the chopped fibers into an annular mold (5) in 40 to 80 concentric iterations of chopped fiber deposition to provide a matrix of fibers in the mold; depositing a curable binder into the mold to intermix the binder with the fiber matrix; compressing the fiber matrix and curable binder within the mold; curing the binder to form a preform matrix; filling the preform matrix with pitch to form a pitch matrix; and subjecting the pitch matrix to chemical vapor deposition to form a carbon-carbon composite preform (15)

Coulomb friction damped disc brake rotors

Abstract: A Coulomb friction damped disc brake rotor, wherein damping is provided Coulomb friction in generally coextensive relation with the braking surfaces of the one or more rotor cheeks. The Coulomb friction damped disc brake rotor has at least one interfacial boundary formed in at least one rotor cheek disposed in generally coextensive relation to the braking surface thereof. The interfacial boundary provides a mechanically distinguishable surface boundary between two surfaces which are in mutual contact such that a state of Coulomb friction exists therebetween.

Electric disc brake apparatus

Abstract: An object of the present invention is to provide an electric disc brake apparatus having a simple constitution in which the operating condition of a parking brake can be reliably detected. A controller detects the operating condition (steps S25, S26) of a solenoid for driving a parking brake locking mechanism (holding mechanism) by means of a motor current (step S24). As a result, a state in which thrust generated by the motor (first electric actuator) is maintained by the parking brake locking mechanism, and accordingly the operative and inoperative states of the parking brake can be understood easily. Further, detection of the motor current is performed using a current sensor that is also used to realize a function of the motor (a function for moving brake pads toward a disc rotor), and hence separate current detection means need not be provided. Accordingly, the operative or inoperative state of the parking brake can be understood by means of a simple constitution, enabling a reduction in the cost of the apparatus.

Creep—Slip Capture as a Possible Source of Squeal During Decelerated Sliding

Abstract: Friction-induced vibration of a two-degree-of-freedom mass-damper-spring system interacting with a decelerating rigid strip is investigated. The friction law is approximated by an analytical function to facilitate the analyses and numerical integrations. It is shown that, after a quasi-harmonic transient period, accompanied by viscous energy dissipation, a short period of intensive ‘creep-slip’ vibration occurs, which generates a series of ‘micro-impacts’ on the strip. Because of the impulsive character of such kind of loading, its Fourier spectrum is rich and quite broadband. Using an averaging technique, the ‘normal form’ equations of motion show that the out-of-phase vibration mode absorbs more energy from the decelerating strip when its natural frequency satisfies certain resonance conditions. The study is then applied to an automotive disc brake model to gain useful insight into the generation of squeal. It is shown that the out-of-phase creep-slip vibration (in the longitudinal direction) of the brake pads generates an impulsive bending moment on the decelerating strip (disc rotor). This impulsive load may be considered as a possible source for brake squeal. The technique developed in this paper may be extended to other ‘squealing systems’ including models for geophysical faults (earthquakes).

Disc for a disc brake

Abstract: The present invention relates to a disc for a disc brake comprising a support bell and braking band being coaxial with each other. The support bell has a plurality of radial housings and the braking band has a plurality of connecting elements suitable to connect it to the bell. The connecting elements are integral and made as one piece with said braking band and overhang from the braking band in order to engage the corresponding radial housings. The connecting elements are at least partially surrounded by walls being integral and made as one piece with the support bell such as to be fastened in the axial direction and in the tangential direction and such as to be capable of sliding in the radial direction.

Self-ventilating disc brake rotor

Abstract: There is a brake disc rotor having a central hub ( 1 ) co-axial with surrounding rings ( 2 ) which form brake bands ( 3 ) for engagement with brake pads. The rings ( 3 ) are supported in a spaced apart parallel configuration with channels ( 12 ) therebetween whereby in use of the rotor cooling air is drawn in through vent openings formed around the inner periphery of the rings ( 3 ) and then radially outwardly through the channels ( 12 ) as the rotor turns. The vent openings include inlet vent ports ( 7 ) on the outboard side of the rotor.

Progressive waviness distortion: a new approach of hot spotting in disc brakes

Abstract: This paper deals with the mechanisms of the appearance of hot spots in railway brake disks. From infrared measurements, a classification of hot spots is presented. The most damaging thermal gradients are identified as macroscopic hot spots uniformly distributed on the friction surface. An explanation of the origin of these macroscopic hot spots is presented based on a scenario of progressive distortion of the disk. Three major effects have to be considered: the structural response of the disk and the pads; realistic boundary conditions, both geometric and loading; and the thermoelastoplastic behavior of the material. Finite element simulations based on the proposed model agree with experimental observations.

Pneumatically or electromotively operable disc brake

Abstract: The invention relates to a pneumatically or electromotively operable disc brake, comprising a brake caliper (1) that overlaps a brake disc (3), at least one tensioning device (2) for tensioning the brake disc (3) by means of a displaceably guided element (11), particularly a traverse. The displaceably guided element (11) has at least one threaded borehole into which an adjusting spindle (10) is screwed. This adjusting spindle supports a pressing piece (5) by means of which a brake pad (4) can be pressed against the brake disc (3). The inventive disc brake also comprises a resetting device (6), which is provided for resetting the clearance and which is actively connected to the adjusting spindle (10), and comprises a securing element, which acts upon the adjusting spindle (10) whereby preventing turning up to a specified torque. The invention is characterized in that the securing element is provided in the form of a spring clip (8) with at least one or more spring saddles (14), which are distributed over the periphery and which rest in a rubbing manner against the adjusting spindle (10) outside the internal thread of the displaceably guided element (11).

Mathematical Model of Brake Caliper to Determine Brake Torque Variation Associated with Disc Thickness Variation (DTV) Input

Abstract: Vehicle brake shudder, or judder, is the result of what is termed brake roughness excitation Objectively, this phenomenon is associated with a brake torque variation (BTV) BTV is the dynamic component of brake torque which is applied to the spindle as an input One of the known mechanical sources of brake torque variation is disc thickness variation (DTV) This source of BTV is associated with the kinematic behaviour of the rotor and caliper from variation in the thickness of the disc rotor The research documented in this paper is related to brake torque variation caused by disc thickness variation A lumped mass-spring mathematical model of the brake caliper system was developed This was used to characterise the dynamic response of the brake assembly to a disc thickness variation input The DTV input was represented mathematically as enforced lateral displacements at the inner and outer rotor/pad interfaces The equations of motion were determined through a Lagrangian approach The solution of these equations was used to describe the caliper dynamics in terms of displacements and forces for each degree of freedom An understanding of these outputs permitted the level of brake torque variation to be calculated The investigation identified the key variables having the largest effect on the level of BTV produced Hence in , a brake caliper mathematical model has been developed which could be used to predict the level of BTV, for a given DTV input, based on the caliper system design variables

Disc Brake Assembly

Abstract: A disc brake assembly includes a brake pad, a pad retainer, a brake caliper, and a pad spring The pad retainer has a planar region situated at a first radius that engages a planar region of the pad spring to restrain radial movement of the brake pad The pad retainer is secured to an outboard side of the caliper at a second radius and has a crook adjacent to the planar region to allow the second radius to be less than the first radius The pad spring has a rounded edge adjacent to the crook

Apparatus for retaining a bicycle disk brake rotor to a bicycle wheel hub

Abstract: An apparatus for fixing a bicycle disk brake rotor a bicycle wheel hub comprises an adapter and a rotor retaining member. The adapter is structured to be nonrotatably coupled to the bicycle wheel hub and to nonrotatably support a disk brake rotor. The adapter includes at least one insertion opening. The rotor retaining member has a latching member structured to be inserted into the insertion opening in the adapter to retain the disk brake rotor to the adapter.

Retraction mechanism for disc brake assembly

Abstract: A disc brake assembly comprises an anchor bracket ( 12 ), a brake shoe ( 10 ) which carries a friction lining ( 16 ), the shoe being slidably supported by the anchor bracket ( 12 ). The assembly includes a retraction mechanism which is adapted to retract the shoe from the disc when the brake is released. The mechanism comprises at least one pin ( 24 ) secured to either a backing plate ( 14 ) or the anchor bracket and a spring clip ( 26 ) fixed relative to the pin which acts between the pin and the other one of the anchor bracket or the backing plate. Deformation of the spring clip as the shoe is moved towards the disc providing a returning force to pull the friction lining away from the disc when the brake is released.

A Through-Process Model of an A356 Brake Caliper for Fatigue Life Prediction

Abstract: The demand for low-cost, high strength-to-weight ratio components continues to drive the development of aluminum alloy castings for new applications. The automotive brake caliper, which has traditionally been made from cast iron, is one such component where aluminum alloys are being considered. The fatigue performance of the brake caliper is an important consideration in evaluating new designs. The use of aluminum alloys in cast components under cyclic loading conditions necessitates a design approach that, in addition to in-service loading, incorporates the impact of microstructural features on fatigue life. In this investigation, a through-process modeling approach has been employed to link a series of mathematical models describing the processing steps of (1) casting, (2) heat treatment, (3) machining, and (4) in-service performance for a preliminary design of a brake caliper made of aluminum alloy A356, Step (1) includes microstructural predictions (secondary dendrite arm spacing and maximum pore size), which are tracked through to the final component. The final lifing of the component combines the effects of these microstructural features with the complex stress state arising from the combined service loading and residual stresses. It was found that all three factors have a strong influence upon the component’s fatigue performance.

Disc brake for vehicle

Abstract: A disc brake for a vehicle has a caliper bracket fixed to a vehicle body, a pair of caliper support arms striding an outer periphery of a disc rotor in a disc axial direction, pad guide grooves formed in the caliper support arms so as to be opposed to each other, friction pads disposed on both sides of the disc rotor, the friction pads having ears projected from both side portions of a back plate thereof, and pad retainers disposed on the pad guide grooves, the ears of the friction pads being movably supported by the pad guide grooves via the pad retainers, wherein pad retainers each has pad returning portions for urging the friction pads away from the disc rotor

Gain stabilizing self-energized brake mechanism

Abstract: A self-energized disk brake assembly includes gain stabilization features for controlling the multiplication of applied force against a rotatable brake member. The brake assembly includes a first brake pad supported about a first pivot and a second brake pad supported about a second pivot. An actuator applies a force to drive the brake pads into the rotatable brake member. Frictional force between the brake pads and the rotatable brake member pulls the brake pads into further engagement generating an increase in braking force from self-energization. A position of the first and second pivots is adjustable to control the amount of braking force generated from self-energization.

Brake caliper for disc brake assembly and method and apparatus for producing same

Abstract: This invention relates to a brake caliper adapted for use in a vehicle disc brake assembly and method and apparatus for producing the same. The method for producing the brake caliper comprises the steps of: (a) providing a mold member having at least two mold sections; (b) providing a core member having at least a first male extension which is adapted to form an integrally cast locating recess in the brake caliper which is used as a locating surface for subsequent machining of the brake caliper; (c) disposing the core member in the mold member in a predetermined position; (d) supplying a suitable material to the mold member so as to form a brake caliper within the mold; (e) removing the brake caliper from the mold, wherein the brake caliper includes an integrally cast locating recess formed therein by the first male extension of the core member; and (f) machining the brake caliper using at least the integrally cast locating recess formed therein as a locating surface.

Pad retraction spring for a brake shoe assembly and a disc brake assembly

Abstract: This invention relates to a pad spring for use in a disc brake assembly. According to one embodiment of the present invention, the disc brake assembly comprises an anchor bracket adapted to be secured to a vehicle component; a brake caliper adapted to be secured to the anchor bracket; an inboard friction pad and an outboard friction pad carried by the disc brake assembly and adapted to be disposed on opposite axial sides of an associated brake rotor; actuation means for selectively moving the inboard and outboard friction pads into frictional engagement with the rotor; and a pad spring carried by at least one end of one of the friction pads for moving the friction pads from engagement with the rotor when the actuation means is released; wherein the pad spring includes a first portion for applying a first retraction force and a second portion for applying a second retraction force which is different from the first retraction force.

Determination of sound radiation from a simplified disk-brake rotor by a semi-analytical method

Abstract: This article describes a semi-analytical procedure to calculate the sound radiated from a simplified disk-brake rotor. First, analytical modal sound radiation solutions of an example of a thick annular disk (with free boundaries) are presented for flexural and radial modes. The analytical solutions were validated by means of experimental and computational methods. Second, the disk sound-radiation solutions were then applied to an example brake rotor. Natural frequencies and mode shapes were computed using a finite-element computer code. Sound-power and radiationefficiency spectra were obtained for both example disks in response to excitation by a multidimensional force. Predictions by the semi-analytical method matched well with predictions obtained using a commercially available computer code for the boundary-element method. The semi-analytical method is computationally efficient and analytically tractable while yielding insights into the contributions of various modes, and their interactions, to the sound radiated from a vibrating disk. © 2004 Institute of Noise Control Engineering

Heat convection and design of brake discs

Abstract: An evaluation method of heat convection from brake discs using analytical and experimental approaches is described. Brake discs may be wheel or axle mounted and either ventilated or solid. ...

Apparatus for the control of brakes in bicycles and the like

Abstract: The invention refers to an apparatus for the control of brakes in bicycles and the like, to be used, in particular, for disc brakes mounted on bicycles and comprising a pump able to push fluid into a hydraulic circuit connected to the brake, characterized in that the pump is held inside the handlebar or a part associated therewith.