ELECTRIC POWER STEERING (EPS)
Electric power steering (EPS or EPAS) uses an electric motor to assist the driver of a vehicle. Sensors detect the position and torque of the steering column, and a computer module applies assistive torque via the motor, which connects to either the steering gear or steering column. This allows varying amounts of assistance to be applied depending on driving conditions. Engineers can therefore tailor steering-gear response to variable-rate and variable-damping suspension systems, optimizing ride, handling, and steering for each vehicle. On Fiat group cars the amount of assistance can be regulated using a button named "CITY" that switches between two different assist curves, while most other EPS systems have variable assist. These give more assistance as the vehicle slows down, and less at faster speeds. In the event of component failure that fails to provide assistance, a mechanical linkage such as a rack and pinion serves as a back-up in a manner similar to that of hydraulic systems.
Electric systems have an advantage in fuel efficiency because there is no belt-driven hydraulic pump constantly running, whether assistance is required or not, and this is a major reason for their introduction. Another major advantage is the elimination of a belt-driven engine accessory, and several high-pressure hydraulic hoses between the hydraulic pump, mounted on the engine, and the steering gear, mounted on the chassis. This greatly simplifies manufacturing and maintenance. By incorporating electronic stability control electric power steering systems can instantly vary torque assist levels to aid the driver in corrective maneuvers.
Electric Power Steering (EPS) is favored over hydraulic power steering in most new vehicles. Eliminating the power steering pump can reduce weight and improve fuel economy. EPS also offers greater handling and steering feel while improving vehicle safety by adapting the steering torque to the vehicle's speed and providing active torque in critical driving situations.
The central electronic elements of today's electric power steering systems are modern 16- and 32-bit MCUs designed for safety-critical applications. Freescale's 16-bit and Qorivva 32-bit single and dual-core MCU provide enhanced computing power and specialized peripherals for complex electric motor control functions. Integrated power supply solutions are also important elements of a power steering control unit. They provide connectivity to automotive busses, such as CAN and LIN. For MOSFET power stages control, integrated pre-drivers are typically used to interface with the MCU directly or via SPI.
DUAL FUEL ENGINES
(CO) and non-methane hydrocarbon (NMHC) emissions is required. Cummins and Dual Fuel
Cummins will produce dual fuel engines for well servicing applications. The engines using Cummins Dual Fuel technology substitute diesel fuel with natural gas in the combustion process, reducing the amount of diesel fuel required to operate frac equipment. The first engine in the Cummins Dual Fuel portfolio for well servicing will be the QSK50, followed by dual fuel for land-based drilling applications, with other QSK Series engines to follow, including engines capable of meeting worldwide emissions regulations. Dual-Fuel engines operate on both natural gas and diesel fuel simultaneously, majority of fuel burned being natural gas. Diesel fuel acts essentially as a ‘spark plug’ as it auto ignites under compression and then ignites the gas. The use of diesel fuel allows the retention of the diesel compression ratio and its efficiency while the natural gas contributes to economy and is responsible for lowering emissions.
The Fumigation Principle
Natural Gas can be introduced to the combustion chamber by either mixing it with the airflow or injecting it into the manifold/chamber. In the Fumigation process, the gas is blended with air and both enter the inlet together in correct proportion whereas in...
Please join StudyMode to read the full document