Electric Parking Brake Research Articles

Analytical Modeling of Heat Transfer Coefficient Analysis in Dimensionless Number of an Electric Parking Brake Using CFD

The present study intends the development of an electric parking brake (EPB) for commercial vehicles (CVs). CVs with EPB applications are currently available in an entirely different set of issues than EPB applications on passenger cars, which are presently widely used. Safe parking requires much more focus with an order of magnitude, more thermal capacity, brake mass, and clamp pressures. In the first instance, heat loss from the brake disc was estimated. The investigations also allowed for precise prediction of radiative heat loss by defining surface emissivity. The parameters of air movement, convective heat transfer coefficients, and velocities were investigated, and validation was done with the CFD model. When the temperature dropped to 252 °C, the maximum estimated value of the Nusselt number was 72.25. Nusselt number pattern that looks identical over the arc surface yields 13.38 percent better results. Nu values at maximum temperature were calculated to be 80.5 and 82.6 at 251.8 °C. The “hconv” value was 4.1 percent lower than in the arc region, with the highest value at 400°C being 11.5 W/m2K. The present study adopted unique approach and obtained brake disc temperature and the coefficient of convective heat transfer on disc friction surfaces and hat regions. CFD modeling was done during the cooling phase to evaluate flow patterns and “hconv” fluctuation across the entire disc brake surface area. The mathematical modeling and adopted methodology for computing heat transfer coefficients for different disc regions have helped to better understand of a CV brake disc heat dissipation.

Numerical and Experimental Investigation of Compressible-Brake-Fluid Flow Characteristics and Brake-Bleeding Performance in EPB Caliper

This study investigates the compressible-brake-fluid flow characteristics within an electric parking brake (EPB) caliper during the bleeding cycles, subsequently determines the fundamental cause for reduction in brake-bleeding performance, and suggests a new design for its improvements. Three-dimensional simulation validation of the brake-fluid consumption curve is conducted through the parameter study of the air mass flow and bulk modulus. A numerical approach utilizing a three-phase (air, brake-fluid, and brake-fluid vapor) mixture model and a standard k-ω turbulence model is adopted to investigate the flow field details. Based on the unsteady simulation results and experimental verifications for the current and new models of the nut-spindle of a driving part in the EPB caliper, the primary cause for the reduction in the bleeding performance in the EPB caliper is determined to be the trapped air in the thread gap and in the space between the spindle and nut-spindle. Consequently, the head chamfer effect for the nut spindle is beneficial for removing trapped air and leads to performance improvement of 30.3 %.

Functional Safety for Developing of Mechatronic Systems - Electric Parking Brake Case Study

The electric parking brake (EPB) system as the complex mechatronic system consists of the actuators that generate the clamping force necessary to hold the vehicle safe, the conventional calipers that convert clamp force into brake torque, electronic hardware with the Electronic Control Unit (ECU), cable harness and switches and especially the control software providing the functions that the driver will experience. Like most of the modern automotive components, the EPB is equipped with embedded electronic systems that include ECU, electronic sensors, signals, bus systems, and coding. Due to the complex application in electrical, electronics and programmable electronics, the need to carry out detailed safety analyses that are focused on the potential risk of malfunction is crucial for automotive systems. This paper describes a possible division of the EPB sub-functions between the supplier the wheel brakes and the supplier which supplying the ECU. Functional safety must be a guarantee with concerning the overall vehicle system. Functional safety is according to the requirements of the ISO 26262 standard and in the context of this paper relates solely to the E/E components (electrical and/or electronic) of the EPB. This paper covers the hazard analysis and risk assessment relevant to the EPB control software, and the derived allocation of ASIL risk levels to the EPB software elements of the functional architecture of the EPB.

An Electric Parking Brake Motor-On-Caliper actuator model for robust drive away control design

Electric Parking Brake system is the automation of traditional manual vehicle parking brake system. Naturally, an automation in automotive field includes an improvement of vehicle features that will become, in short time, normal production functionalities, since forever present on vehicles for users. Certainly, EPB control design is a robust design which is influenced by a series of different plant disturbances / uncertainties as: available vehicle battery voltage, ambient/caliper/pad temperatures, vehicle harness length, and normal braking hydraulic pressure already present on caliper spindle. Furthermore EPB system performance has a big impact on vehicle safety, ECE 13H braking legislation part related to parking brakes prescribes many different performance thresholds, static and dynamic, that are easily translated in low level control design requirements. In this context, paper presents: an algebraic mathematical model, including linear and non-linear parts of braking motor-on-caliper, dynamic response identification of electric parking brake actuator by least square identification experiments, linearization of identified non-linear model, observability analysis of identified linear model, and control of Motor on Caliper (MoC) validated with MIL and HIL approach. The simulation and experimental results on a motor-on-caliper test bench, carried out in FCA Technical Center, show that designed identified model is well matched with the clamping force actuator, and it can be useful in drive away robust control logics development.

Design of a Cable Pulled Electric Parking Brake System for Light Commercial Vehicle

In order to solve the insufficient parking brake force and other problems of mechanical parking brake system in light commercial vehicle, a cable pulled electric parking brake system had been designed. The hardware and the control strategy of the system had been put forward; In order to verify the feasibility and reliability of cable pulled electric parking brake system, the modeling and simulation of mechanical and electrical parts were completed with MATLAB/Simulink. The simulation results show that the designed maximum braking torque is 5107.38 Nm, which meets the national related standard for parking brake system. The whole parking brake process only takes 1064.1 ms, it is very fast. This design makes parking brake system more intelligent, improves the safety and comfort of light commercial vehicle.

A study of an electric parking brake system for emergency braking

In this paper, an emergency braking control with electric parking brake (EPB) actuator is proposed and studied. Emergency braking requires a good slip ratio control algorithm to guarantee the brake stability. It is well known that the X-by-wire technologies have considerable advantages over the traditional hydraulic system, especially, bringing great strengths to complex control systems. As one of the brake-by-wire systems, EPB has been used as an advanced parking system in some luxury cars. However, it still has some untapped potential, e.g., dynamic braking. The paper proposes a sliding mode control (SMC) algorithm to effectively control the dc motor in EPB system to attenuate the torque tracking error. Simulation results from a quarter vehicle model with EPB actuator as a spare dynamic braking system show that the proposed control architecture with three sliding surfaces can effectively improve the emergency braking performance in the typical simulation manoeuvres employed and significantly reduce the tracking errors.

Clamping Force Control for an Electric Parking Brake System: Switched System Approach

This paper addresses the modeling, controller design, and stability analysis of an electric parking brake system in which a screw-nut self-locking mechanism is used. The system is modeled as a state-dependent switched system according to the operating mode. A nonlinear proportional (P) clamping force controller using the measured force is proposed to enhance the performance specifications. We show the uniform stability of the state-dependent switched system with the nonlinear P controller using a common Lyapunov theorem and LaSalle's invariance principle. We derive the conditions to assure stable self-locking operation of the system. We also show the existence of the largest invariant set depending on the target braking force. This analysis offers a guideline as to how a nonlinear controller can be designed in view of the self-locking stability and control performance. Through simulation and experimental results, we confirm that the solution is locally uniformly ultimately bounded. Through the experimental results, we show that the nonlinear P controller outperforms a simple on/off controller in terms of the average and deviation of the braking force error. Furthermore, it is experimentally verified that the system is also able to function as a pseudo-antilock braking system.

Slide Mode Control for Integrated Electric Parking Brake System

The emerging integrated electric parking brake (IEPB) system is introduced and studied. Through analyzing the various working stages, the stages switched IEPB system models are given with the consideration of the friction and system idle inertia. The sliding mode control (SMC) method is adopted to control the clamping force by the widely used motor angle and clamping force relationship method. Based on the characteristics of the state equations, two sliding surfaces are built to control the motor angle and current, respectively. And in every working stage, the control stability is guaranteed by choosing the control parameters based on Lyapunov theory and SMC reachability. The effectiveness of the proposed control system has been validated in Matlab/Simulink.

차량 시스템의 소음 기여도분석 및 공진 규명을 통한 전자식 주차 브레이크 소음원 규명

Caliper intergrated Electric Parking Brake (EPB) is an automatic parking brake system, attached to rear caliper. Because EPB uses luxury vehicles recently, the drivers of vehicles are sensitive to the EPB noise. EPB is operated by the motor and gear, so noise is generated by motor and gear. In order to reduce noise, One of EPB manufacturers uses helical gear and changes the shape of EPB housing. But these methods are not optimized for reduction of interior noise. There are many noise transfer paths into vehicle interior and it is difficult to identify the noise sources. Therefore, in this study, we performed contribution analysis and modal testing in the vehicle system. It is possible to distinguish between air-borne noise and structure-borne noise in the vehicle interior noise by comparing interior noise peak with resonance mode map.

Fault detection method for electric parking brake (EPB) systems with sensorless estimation using current ripples

A fault detection method with parity equations is proposed in this paper. Due to its low cost implementation, the velocity of the motor is not measurable in electric parking brake (EPB) systems. Therefore, residuals are not reliable when estimating the motor velocity with a low-resolution encoder. In this paper, we propose a fault detection method with sensorless estimation using current ripples that estimates the position and velocity of the motor by detecting periodical oscillations of the armature current caused by rotor slots. In addition, this method can estimate the position and velocity of the motor with less computational effort than a state observer. Moreover, the method is less sensitive to motor parameters than model-based estimation methods. The effectiveness of this method is validated with experimental data, and the simulation results show that various faults have their own residual patterns. Therefore, we can detect the presence of faults by monitoring the residual signals.

Design and Testing of a New Electric Parking Brake Actuator

There are two types of existing EPB. One is the cable puller, and the other is the caliper. This new concept design belongs to the cable puller type. Many design concepts of the cable puller type use the ways of two cables [1,2]. Some perhaps use one cable to connect by way of the balancer one divides into two brakes [3]. Minorities also use the design concept of one cable method [4,5], which has small curvature radius of cable that will reduce the cable life and mechanical efficiency. The new concept design of this paper will also use one cable to connect two sides of the parking brake, but still maintain the cable life and mechanical efficiency.

Smart parking brake distributes electric park brake functions

In 2002, TRW Automotive introduced the first calliper integrated electric parking brake in the world. Since then, the Electric Parking Brake (EPB) has been launched in over 20 vehicle models — from luxury to midrange platforms. The new Smart Parking Brake (SPB) System presented by TRW removes the requirement for the electric parking brake to have a separate Electronic Control Unit, integrating the EPB into existing systems such as electronic stability control. The new SPB system creates the opportunity for systems integration at a higher level.

Stability Analysis of an Electric Parking Brake (EPB) System with a Nonlinear Proportional Controller

In this paper, an Electric Parking Brake (EPB) system is modelled as a state-dependent switched system. The model involves screw friction which varies depending on the operation region. A new nonlinear proportional (P) controller is proposed and its stability is analyzed via Lyapunov and LaSalle's theory. It is shown that the equilibrium point is locally uniform and ultimately bounded.