Thursday, August 29, 2013

FUNDAMENTAL OF AUTOTRONIC

AUTOTRONIC

Autotronic merupakan gabungan pelbagai kemahiran seperti berikut :


Penguasaan pelbagai kemahiran membolehkan seseorang itu menjadi kreatif dan menghasilkan rekacipta. Untuk menguasai sesuatu kemahiran, kita perlu memahami asal-usul (fundamental) bidang tersebut. 

Fundamental kepada autotronic terbahagi kepada 3 bahagian, iaitu:





Posted by at No comments:

Saturday, August 10, 2013

ACTIVE vs SEMI-ACTIVE SUSPENSION ANALYSIS


MODULE OBJECTIVE :

At the end of this module, trainee must be able to :

1. Understand difference between active and semi-active suspension.
2. Understand between active and passive suspension
3. Hydraulic Actuated Systems
4. Electromagnetic Recuperative
5. Solenoid/valve Actuated
6. Magneto Rheological Damper


TYPES OF SUSPENSIONS
Fig.1 : Types of Suspensions
  • Passive
    • Movement determined entirely by surface vehicle is riding on.
Fig.2 : Bicycle is passive or no suspension system
  • Semi-Active

    • Only changes viscous damping coefficient of shock absorber.

Fig.3: Semi-Active Suspensions System
  • Active
    • Use independent forces on the suspension to increase riding characteristics.


Fig.4: Active Suspension system layout in vehicle
Fig.5: Shock Absorber layout for active suspension system.

Fig.6: Active Suspension system in axle location.

Fig.7: Active Suspension on bus using Air Suspension System

Fig.8: Voice-Coil-Motor System for Active Suspension System


Active Vs. Passive Suspension

Advantages                                                                      

  • Virtually eliminates body roll and pitch variation.               
  • Better ride quality                                                                 
  • Better handling                                                                        

Disadvantages


  • Expensive
  • Added Complication
  • Can be difficult to reliably diagnose




Hydraulic Actuated Systems

Fig. 8: Hydraulic Actuated Systems

žControlled by hydraulic servomechanisms
žžSelf Leveling and Height Adjustment
žLowers height at high speeds
žžDeveloped in 1980’s


Electromagnetic Recuperative

žBose System
                Released in 2009
Uses Linear Electromagnetic motor at each wheel
Possible “Drop-in” Installation


Fig.9:  Electromagnetic Recuperative in vehicle.

 Solenoid/Valve Actuated

 Most basic semi-active suspension
žžAlters flow of hydraulic fluid inside shock absorber
Air ride suspensions



Fig.10: Air Suspension system
Fig.11: Pneumatic components for air suspension system

Fig.12: Air Suspension system on vehicle


Magneto Rheological Damper

žAudi System
Magnetic field changes alignment of the particles
Increasing current flow in damper raises spring stiffness
—žOriginally developed in the 1980’s
Finding increased usage in the USA







Fig.13:  Magneto Rheological Damper

Conclusion

Active Suspension

žMore expensive
žProvides extremely good suspension performance
žžProvides excellent ride quality
žžVery complex systems, since the vehicle must be able to manipulate the suspension in many different ways. 

Semi-Active Suspension
žMuch cheaper
žPerformance can be very comparable to active suspension
žRide quality also can be very similar to active suspension
žMuch simpler systems than active suspensions, since only the damping coefficient changes
Resources informations:
Posted by at No comments:

Sunday, August 4, 2013

ELECTRONIC CONTROL SUSPENSION SYSTEM

ECS - Electronically Controlled Suspension


The main purpose of the ECS is to adapt the suspension of the car into the driving conditions taking account the speed, surface of the road, cornering, stopping requirements and acceleration. The aim is to increase safety and driving comfort. The basic driving characteristics of the car can be changed from a soft, smooth ride to a hard driving experience of a sports car and everything between. All should happen quickly and continuously. The driver has an option for select for manual selection by pushing a button to drive continuously in sport, normal or comfort mode.
The purpose of an accelerometer is to measure the car body motion and, in some cases, the vertical motion of the front wheels. The car body motion is measured by two accelerometers located very close to the upper fixing point of the front shock absorbers and springs. The wheel hub sensors are located at the other end of the shocks and springs next to the wheel. The idea is to measure the difference in vertical motion between the wheel and the body. In more modern systems the wheel hub sensors have been replaced by position sensors, which directly measure the distance between the wheel and body.
Most systems also include one accelerometer in the middle or rear part of the car's to measure pitch of the car. The aim of this feature is to reduce the inclination of the car when accelerating and braking.
Today the majority of new cars in the luxury and upper middle class range, including some Sport Utility Vehicles (SUVs), have air suspension. The volume of the air in the air cushions in all corners of the car can be controlled. This is done by controlling the flow of the air in and out of the additional air reservoirs. The system includes a special air compressor, one or two air reservoirs, four shock absorber units with air springs and traditional shock absorbers, 2 to 5 stand-alone accelerometers and the electronic control unit (ECU).
The alternative solution is to control the flow of oil inside traditional shock absorbers. The flow of oil is controlled by special electrically controlled valves inside the shock absorber. The system contains 3 or 5 stand alone accelerometers. 

Active suspension


The active suspension and adaptive suspension/semi-active suspension are types of automotive suspensions that controls the vertical movement of the wheels with an onboard system, rather than in passive suspensions where the movement is being determined entirely by the road surface.
This technology allows car manufacturers to achieve a greater degree of ride quality and car handling by keeping the tires perpendicular to the road in corners, allowing better traction and control. An onboard computer detects body movement from sensors throughout the vehicle and, using data calculated by opportune control techniques, controls the action of the active and semi-active suspensions. The system virtually eliminates body roll and pitch variation in many driving situations including cornering, accelerating, andbraking.
Active suspensions can be generally divided into two main classes: pure active suspensions and adaptive/semi-active suspensions. While adaptive suspensions only vary shock absorber firmness to match changing road or dynamic conditions, active suspensions uses some type of actuator to literally raise and lower the chassis independently at each wheel.
Manufacturer brand names for adaptive suspensions include Airmatic suspension (Mercedes-Benz), Adaptive Damping, and Road-Sensing Suspension. Active suspensions include Active Body Control (Mercedes-Benz) and Active Roll Stabilization (BMW). For instance, in the 2005 model year, the Mercedes-Benz S55 AMG has the Active Body Control active suspension as standard equipment, while the Mercedes-Benz S430 comes with the Airmatic adaptive suspension and has Active Body Control as an option.According to The Truth About Cars, Active Body Control (ABC) "senses body movement and strangles it at birth. The PRE-ALPHABETIZED electro-hydraulic doohickey makes a 4300lbs. sports sedan handle like a 3000lbs. sports sedan"


Active

Active suspensions, the first to be introduced, use separate actuators which can exert an independent force on the suspension to improve the riding characteristics. The drawbacks of this design (at least today) are high cost, added complication/mass of the apparatus, and the need for rather frequent maintenance on some implementations. Maintenance can be problematic, since only a factory-authorized dealer will have the tools and mechanics with knowledge of the system, and some problems can be difficult to diagnose.
Michelin's Active Wheel incorporates an in-wheel electrical suspension motor that controls torque distribution, traction, turning maneuvers, pitch, roll and suspension damping for that wheel, in addition to an in-wheel electric traction motor.















Hydraulic actuated

Hydraulically actuated suspensions are controlled with the use of hydraulic servomechanisms. The hydraulic pressure to the servos is supplied by a high pressure radial piston hydraulic pump. Sensors continually monitor body movement and vehicle ride level, constantly supplying the computer with new data. As the computer receives and processes data, it operates the hydraulic servos, mounted beside each wheel. Almost instantly, the servo-regulated suspension generates counter forces to body lean, dive, and squat during driving maneuvers.
In practice, the system has always incorporated the desirable self-levelling suspension and height adjustable suspension features, with the latter now tied to vehicle speed for improved aerodynamic performance, as the vehicle lowers itself at high speed.
Colin Chapman developed the original concept of computer management of hydraulic suspension in the 1980s to improve cornering in racing cars. Lotus developed a version of its 1985 Excel with electro-hydraulic active suspension, but never offered it for sale.
Computer Active Technology Suspension (CATS) co-ordinates the best possible balance between ride quality and handling by analysing road conditions and making up to 3,000 adjustments every second to the suspension settings via electronically controlled dampers.

Electromagnetic recuperative


This type of active suspension uses linear electromagnetic motors attached to each wheel. It provides extremely fast response, and allows regeneration of power consumed by utilizing the motors as generators. This nearly surmounts the issues of slow response times and high power consumption of hydraulic systems. It has only recently come to light as a proof of concept model from the Bose company, the founder of which has been working on exotic suspensions for many years while he worked as an MIT professor. Electronically controlled active suspension system (ECASS) technology was patented by the University of Texas Center for Electromechanics in the 1990s and has been developed by L-3 Electronic Systems for use on military vehicles. The ECASS-equipped HMMWV exceeded the performance specifications for all performance evaluations in terms of absorbed power to the vehicle operator, stability and handling.

Adaptive/Semi-active

Adaptive/semi-active systems can only change the viscous damping coefficient of the shock absorber, and do not add energy to the suspension system. Though limited in their intervention (for example, the control force can never have different direction than the current vector of velocity of the suspension), semi-active suspensions are less expensive to design and consume far less energy. In recent times, research in semi-active suspensions has continued to advance with respect to their capabilities, narrowing the gap between semi-active and fully active suspension systems.

Solenoid/valve actuated


This type is the most economic and basic type of semi-active suspensions. They consist of a solenoid valve which alters the flow of the hydraulic medium inside the shock absorber, therefore changing the damping characteristics of the suspension setup. The solenoids are wired to the controlling computer, which sends them commands depending on the control algorithm (usually the so-called "Sky-Hook" technique). This type of system used in Cadillac's Computer Command Ride (CCR) suspension system.


Magneto rheological damper


Another fairly recent method incorporates magneto rheological dampers with a brand name MagneRide. It was initially developed by Delphi Corporation for GM and was standard, as many other new technologies, for Cadillac Seville STS (from model 2002), and on some other GM models from 2003. This was an upgrade for semi-active systems ("automatic road-sensing suspensions") used in upscale GM vehicles for decades. It allows, together with faster modern computers, changing the stiffness of all wheel suspensions independently. These dampers are finding increased usage in the US and already leases to some foreign brands, mostly in more expensive vehicles. In this system, being in development for 25 years, the damper fluid contains metallic particles. Through the onboard computer, the dampers' compliance characteristics are controlled by an electromagnet. Essentially, increasing the current flow into the damper raises the compression/rebound rates, while a decrease softens the effect of the dampers. Information from wheel sensors (about suspension extension), steering, acceleration sensors and some others is used to calculate the optimized stiffness. The fast reaction of the system allows, for instance, make softer passing by a single wheel over a bump in the road.

Posted by at 1 comment:

DIESEL COMMON RAIL

Common rail direct fuel injection is a modern variant of direct fuel injection system for petrol and diesel engines.
On diesel engines, it features a high-pressure (over 1,000 bar or 15,000 psi) fuel rail feeding individual solenoid valves, as opposed to low-pressure fuel pump feeding unit injectors (Pumpe/Düse or pump nozzles). Third-generation common rail diesels now feature piezoelectricinjectors for increased precision, with fuel pressures up to 3,000 bar or 44,000 psi.[1][2]
In gasoline engines, it is used in gasoline direct injection engine technology.
commonrail flow


commonrail parts


The common rail system prototype was developed in the late 1960s by Robert Huber of Switzerland and the technology further developed by Dr. Marco Ganser at the Swiss Federal Institute of Technology in Zurich, later of Ganser-Hydromag AG (est.1995) in Oberägeri.
The first successful usage in a production vehicle began in Japan by the mid-1990s. Dr. Shohei Itoh and Masahiko Miyaki of the Denso Corporation, a Japanese automotive parts manufacturer, developed the common rail fuel system for heavy duty vehicles and turned it into practical use on their ECD-U2 common-rail system mounted on the Hino Rising Ranger truck and sold for general use in 1995.[3] Denso claims the first commercial high pressure common rail system in 1995.[4]
Modern common rail systems, whilst working on the same principle, are governed by an engine control unit (ECU) which opens each injector electronically rather than mechanically. This was extensively prototyped in the 1990s with collaboration between Magneti Marelli,Centro Ricerche Fiat and Elasis. After research and development by the Fiat Group, the design was acquired by the German companyRobert Bosch GmbH for completion of development and refinement for mass-production. In hindsight, the sale appeared to be a tactical error for Fiat, as the new technology proved to be highly profitable. The company had little choice but to sell, however, as it was in a poor financial state at the time and lacked the resources to complete development on its own.[5] In 1997 they extended its use for passenger cars. The first passenger car that used the common rail system was the 1997 model Alfa Romeo 156 2.4 JTD,[6] and later on that same year Mercedes-Benz C 220 CDI.
Common rail engines have been used in marine and locomotive applications for some time. The Cooper-Bessemer GN-8 (circa 1942) is an example of a hydraulically operated common rail diesel engine, also known as a modified common rail.
Vickers used common rail systems in submarine engines circa 1916. Doxford Engines Ltd.[7] (opposed-piston heavy marine engines) used a common rail system (from 1921 to 1980) whereby a multi-cylinder reciprocating fuel pump generated a pressure of approximately 600 bar, with the fuel being stored in accumulator bottles. Pressure control was achieved by means of an adjustable pump discharge stroke and a "spill valve". Camshaft-operated mechanical timing valves were used to supply the spring-loaded Brice/CAV/Lucas injectors, which injected through the side of the cylinder into the chamber formed between the pistons. Early engines had a pair of timing cams, one for ahead running and one for astern. Later engines had two injectors per cylinder, and the final series of constant-pressure turbocharged engines were fitted with four injectors per cylinder. This system was used for the injection of both diesel oil and heavy fuel oil (600cSt heated to a temperature of approximately 130 °C).
The common rail system is suitable for all types of road cars with diesel engines, ranging from city cars such as the Fiat Nuova Panda to executive cars such as the Audi A6.

Common rail today

 

Bosch common rail diesel fuel injector from a Volvo truck engine

Ashok Leyland's CRS Engines (used in U Truck and E4 Busses)Robert Bosch GmbH, Delphi Automotive Systems, Denso Corporation, and Siemens VDO (now owned by Continental AG) are the main suppliers of modern common rail systems. The car makers refer to their common rail engines by their own brand names:

Principles


Common Rail Scheme.svg 

Solenoid or piezoelectric valves make possible fine electronic control over the fuel injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel atomisation. In order to lower engine noise, the engine's electronic control unit can inject a small amount of diesel just before the main injection event ("pilot" injection), thus reducing its explosiveness and vibration, as well as optimising injection timing and quantity for variations in fuel quality, cold starting and so on. Some advanced common rail fuel systems perform as many as five injections per stroke.[8]
Common rail engines require a very short (< 10 seconds) to no heating-up time[citation needed], depending on ambient temperature, and produce lower engine noise and emissions than older systems[citation needed].
Diesel engines have historically used various forms of fuel injection. Two common types include the unit injection system and the distributor/inline pump systems (See diesel engine and unit injector for more information). While these older systems provided accurate fuel quantity and injection timing control, they were limited by several factors:
  • They were cam driven, and injection pressure was proportional to engine speed. This typically meant that the highest injection pressure could only be achieved at the highest engine speed and the maximum achievable injection pressure decreased as engine speed decreased. This relationship is true with all pumps, even those used on common rail systems; with the unit or distributor systems, however, the injection pressure is tied to the instantaneous pressure of a single pumping event with no accumulator, and thus the relationship is more prominent and troublesome.
  • They were limited in the number and timing of injection events that could be commanded during a single combustion event. While multiple injection events are possible with these older systems, it is much more difficult and costly to achieve.
  • For the typical distributor/inline system, the start of injection occurred at a pre-determined pressure (often referred to as: pop pressure) and ended at a pre-determined pressure. This characteristic resulted from "dummy" injectors in the cylinder head which opened and closed at pressures determined by the spring preload applied to the plunger in the injector. Once the pressure in the injector reached a pre-determined level, the plunger would lift and injection would start.
In common rail systems, a high-pressure pump stores a reservoir of fuel at high pressure — up to and above 2,000 bars (29,000 psi). The term "common rail" refers to the fact that all of the fuel injectors are supplied by a common fuel rail which is nothing more than a pressure accumulator where the fuel is stored at high pressure. This accumulator supplies multiple fuel injectors with high-pressure fuel. This simplifies the purpose of the high-pressure pump in that it only has to maintain a commanded pressure at a target (either mechanically or electronically controlled). The fuel injectors are typically ECU-controlled. When the fuel injectors are electrically activated, a hydraulic valve (consisting of a nozzle and plunger) is mechanically or hydraulically opened and fuel is sprayed into the cylinders at the desired pressure. Since the fuel pressure energy is stored remotely and the injectors are electrically actuated, the injection pressure at the start and end of injection is very near the pressure in the accumulator (rail), thus producing a square injection rate. If the accumulator, pump and plumbing are sized properly, the injection pressure and rate will be the same for each of the multiple injection events.



Posted by at No comments:
Subscribe to: Posts (Atom)