P4-Explore Integrated Electronic Parking Brake System
An electronic parking brake (EPB), also known as an electric parking brake or electric park brake, is an electronically controlled parking brake, whereby the driver activates the holding mechanism with a button and the brake pads are electrically applied to the rear wheels.[1] This is accomplished by an electronic control unit (ECU) and an actuator mechanism. There are two mechanisms that are currently in production, Cable puller systems and Caliper integrated systems.EPB systems can be considered a subset of Brake-by-wire technology.
Functionality
Apart from performing the basic vehicle holding function required of park brakes, the EPB systems provide other functions like automatic release of the park brakes when the driver presses the accelerator or slips the clutch, and re-clamping using additional force on detection of vehicle motion.[2] Further, the hill-hold function, which applies brakes to prevent roll-back when pulling away on a gradient, can also be implemented using the EPB
A new design of integrated Electric Parking Brake system, called iEPB and integrated in the brake caliper, is introduced in this paper. It consists of an electrically operated brake unit and a hydraulically pressed unit independently, and uses a special self-locking mechanism instead of a screw device to increase the efficiency and the working speed. With all conventional EPB system’s advantages, it also provides a stronger brake performance and a faster reaction time. In this paper, we describe the working principle of this new design at first, and then introduce the arrangement of the testing system, followed by a discussion of experimental data. The testing results prove the feasibility of this design. The conclusion paragraph summarizes the key points about the design of the iEPB system. INTRODUCTION The iEPB system is more convenient and safety than traditional parking systems. It’s operated and released automatically. With integrated intelligent function, the iEPB system has the following merits: • Replace a hand lever by an operation button. • Because of no hand lever, there is more space in the vehicle. • Combining a control unit, the iEPB system can be automatically operated and released at the right time, which makes the operation simpler and the driver to feel more comfortable and safer. • With high performance mechanism, the iEPB system has a faster reaction time. So we can provide the Auto-Hold function by adopting the iEPB system. There are two types of existing electric parking brake. One type is the cable puller[3], and the other is the integrated caliper[4]. This new design belongs to the integrated caliper type. Almost 100% integrated caliper type of market products use the screw device as its linear mechanism. The screw device can provide a large reduction ratio in a small space and transfer the rotation motion into linear motion with a non-reverse feature. But a low mechanical efficiency due to the screw friction makes a great energy lose. In this paper, we introduce a new design that is a type of screw free concept. Basing on the same power source, the screw free design can reduce about three-quarter reaction time of the system
SYSTEM DESCRIPTION For improving working speed, enhancing mechanism efficiency and providing a non-reverse feature at the same time, the iEPB mechanism design is the key point. The important factors that need to be considered include:
Caliper pressing force. • Working time of the actuator. • Power consumption. • Parking force that can be maintained when power off.
