P RODUCTS

The concept of the EPB system was supposed firstly in 1996 [15]. Several foresighted corporations started to apply for the patents of these new techniques. After developing for several years, vehicle companies and component manufacturers attempted to produce a usable commercial product. The Lincon Corp. starts to set up the EPB system in their LS type vehicles in 2003. Then, many other companies started to install the EPB system in their vehicles. (Table 2.3-1) For example, the Jaguar XJ and S-type, the Audi A6 and A8, the Renault New Vel Satis and Scenic, the BMW 7-Series and the Volkswagen Passat all have the EPB system in their vehicles from 2003 to 2005. In past, the EPB was limited to expensive vehicles. However, after the success of EPB system in these vehicles, moddle-level vehicles, such as the Ford Focus and G-Max, use the EPB system nowadays. In addition, there are at least eight types of vehicles plan to set the EPB system in 2006. As a result, more customers will anticipate using the new system after the price decreasing. It is believed that the EPB system may become a basic equipment by which the EPB market will have a bright future.

Companies Types Companies Types

LS 7-Series

XJ and S-type New Passat

Focus and

Table 2.3-1 Commercial Products of the EPB System

Besides, the EPB system is not all manufactured by the vehicle companies. Some products are cooperated by both vehicle companies and the vehicle component manufacturers.

For manufacturers, they may choose to cooperate with vehicle companies or independently design the system by themselves. On the one hand, if the manufacturer chooses the former, they can get classified information and the cost of the product can be decreased efficiently.

For example, the TRW corp., one famous component manufacturer in Germany, has cooperated with Renault for developing the EPB system installed in Scenic. Cooperation makes designs more transparent. Connecting attached system with the Electronic Control Unit

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(ECU) of vehicles can make the cost down. Nevertheless, the market of the product will be limited to certain type of vehicles, because of the compatibility of the specification.

On the other hand, if these manufacturers choose the latter, the necessary information of researches and developments, such as the sensor signals and the control logic, will not easy to been acquired. And the functions between components can not easily be integrated. For the reason, the function of product will be restricted and the cost will increase. For instance, the microeletrical brake system (MBS) Corp., a vehicle companies in Taiwan, has invented an independent component without cooperating with any vehicle companies. The product only has some basic functions required for an EPB system, such as switch on/off. However, the market and the compatibility will be expanded because of the property of independent controlling. The list of the manufacturers of the EPB system is listed in Table 2.3-2.

Country Company

Table 2.3-2 Manufacturers of the EPB System

Although, there are two different development tendencies, the objectives are the same (Table 2.3-3), including simple mechanism, high efficiency, self-lock, adjustable force, small volume of motor, low cost, and rare failure.

Objectives Numbers

Simple Mechanism 33

High Efficiency 16

Self-Lock 13

Adjustable Force 8

Small Volume of Motor 5

Low Cost 4

Rare Failure 3

Sliding Avoiding 2

Table 2.3-3 The Objectives of the Patents of the EPB System

Therefore, available EPBs can be divided into two types: single component and complete system (Fig 2.3-1). Single component is usually provided by small manufacturers, and their target market always concentrates on customers whose car has no EPB initially. For this reason, it must be simple, low cost, and easy installation. Conversely, the complete system is usually developed by vehicle companies. The objectives of such product are to increase the selling price and improve the performance of their vehicles. As a result, the complete system needs to be multi-functions and high qualities, and the cost of it is always higher than the single component.

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Fig 2.3-1 Tendencies of the EPB System

2.3.1

MBS Corp. is a Taiwanese company, and they don’t cooperate with any vehicles company. Its target market concentrates on common users. Therefore, the product is compatible for any kind of vehicles, including AT or MT vehicles. Users can buy the product from retailers and install it by themselves. However, the more compatibility it has, the less functions it contains. Therefore, this simple product cannot meet the entire requirement for customers.

Complete System Single Component

EPB

ABS EPB BAS

TCS ETC ESP AT MT AMT

Insert to Vehicle Vehicle Product

The function and the control logic of the MBS product are simple, and can be divided into two modes, automatic and manual mode (Table 2.3-4). The logic of the automatic mode are different between AT and MT vehicles. For example, for an AT vehicle, the brake will engage when the shifting lever is at N position. And the brake will disengaged when the shifting lever is at R or D position. However, for a MT vehicle, the system will engage the brake when the vehicle stop (speed is equal to zero). And the system will disengage the brake when the user steps on the gas pedal. Furthermore, if users want to actively operate the system, they can turn on/off the switch to engage/disengage the brake easily.

Mode Type Brake Situation

Engage Shifting lever at N position AT

Disengage Shifting lever at R or D position

Engage Stop Automatic

MT

Disengage Step on the gas pedal

Engage Turn on the switch

Manual

Disengage Turn off the switch

Table 2.3-4 Logic Control of the EPB System of MBS

2.3.2

Renault’s product is designed by Renault and TRW. The functions of the product can be divided into two parts: automatic and manual mode. Each detailed operation is described in Table 2.3-5. It is suitable for use in both AT and MT vehicles (only for Renault vehicles).

However, the functions mentioned below are depending on the product designed for AT

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vehicles (Table 2.3-5). The function and the logic control of this product are difficult than MBS. For the automatic mode, the brake will be engaged when the user turns off the ignition, and be disengaged when the user steps on the gas pedal. On the contrast, for the manual mode, the brake will be engaged when the user turns on the switch, and be disengaged when the user turns off the switch and push safety button.

Furthermore, the product comprises more safety functions, such as disengaging when driving and warming signals as components get failure. The brake force also can be adjusted if the user pushes the switch more strongly or longer. Besides, the product even provides a manual releaser installed in rear box of vehicle for emergency.

Mode Brake Situation

Engage Turn off ignition

Automatic

Disengage Step on the gas pedal

Engage Turn on the switch

Manual

2.Double check (LED and button light) 3.Manual releaser when failing

4.Adjustable force

Table 2.3-5 Logic Control of the EPB System of Renault Scenic

2.3.3

“Audi” is treated as a symbol of high level vehicles. The performance of product is superior, and the functions and the logic control are very complicated. It can be divided into two modes, automatic mode and manual mode (Table 2.3-6). Generally speaking, the user should always uses the manual mode to make the brake engaging, and the automatic mode to make the brake disengaging. But the system can make the brake engaging automatically to avoid the vehicle sliding down on a hill. And the user also can directly turn on the switch to make the brake disengaging.

In Audi products, hill holder is a special function that does not appear in middle-level vehicles now. The brake force can be adjusted according to the gradient automatically. In addition, the manual releaser is also an essential requirement. Furthermorer, the system applies other additional functions, including the temperature compensation and brake attrition feedback. These functions make the vehicle more convenient safer.

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Mode Brake Situation

Engage On a hill

Automatic

Disengage Step on the gas pedal and set the safety belt

Engage Turn on the switch

Manual

Disengage Turn off the switch

Special Functions

1. Hill holder

2. Drum attrition feedback 3. Temperature compensation 4. Manual releaser when failing

5. Double check (LED and button light) 6. Adjective force

Table 2.3-6 Logic Control of the EPB System of Audi A6 and A8