Innovative Hill Start Assistance Device

Abstract

The hill start in manual or automated manual transmission vehicles is faced by most users as inconvenient situation. In the time interval between brake pedal releasing and gas pedal pressing, the car might roll backwards, causing an unsafe or at least uncomfortable situation. The device currently presented offers a simple solution that assists the driver in such situation, keeping the vehicle stopped while the driver releases the brake pedal and requests enough engine torque to safely start in hill condition. The simplicity of the device allows its assembly in manual, automated manual or even automatic transmission cars, with or without anti-lock brake system and it also ensures its use from the lowest to the top range of vehicles. The operation principle is based on a directional valve assembled in the brake line which is only activated when all the logic conditions are redundantly checked on a hill start situation. An accelerometer is used to identify the exact hill inclination in which is the vehicle and calculate the required engine torque for a safe start. INTRODUCTION A complex arrangement of factors defines whether or not a new vehicle will become a market success. The continuously more restrictive emission regulation and the increasing concernment regarding fuel consumption have been pushing the powertrain development for new standards on every vehicle launch. Aiming efficiency, several innovative technologies have reached production lines such as downsized engines, hybrid cars and large variety of gearboxes with different principles and several gear ratios. Safety technologies have equally been largely spread over the past few years. In Brazil, the use of anti-lock brake system is defined as obligatory for all vehicles manufactured after January 1st 2014 [1]. The same definition applies to the use of airbags [2]. Despite the legislation, which defines the minimum requirements, the automotive market itself is even more demanding for safety matters. To ensure competitiveness, the basic rule for vehicles is to offer the larger number of features for the lowest price, ensuring the value from the costumers’ perspective. A frequent situation that causes concern for drivers is starting the car in a hill situation without any rollback. This action requires considerable expertise and concentration from the driver and may cause stress in critical hill situations such as maneuvering is tight parking spaces or heavy traffic with frequent stops and starts. If the car rolls to the unintended direction, there is the risk of accident. The vehicle parts are also exposed to abnormal wear if the driver creates excessive clutch slipping during the start. The situations listed above are more applicable to cars with manual or automated manual transmission gearboxes. Nevertheless, automatic transmission vehicles may also be submitted to rollback on hill start if the residual transmission torque is not high enough to keep the vehicle completely stopped. In order to provide assistance to the driver in hill start situation, the device herein presented was developed to prevent the vehicle from rolling in the time interval between brake pedal release and sufficient gas pedal pressing. The purpose of the development is to offer a simple – and therefore massively applicable – solution a very frequent issue faced on a frequent basis by drivers.