International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 8, August 2012)

Performance & Value Analysis of Power Steering System Bhushan Akhare1, Sanjeev S Chouhan2 1

Bhushan Akhare M.Tech Mechanical Engineering Student & JIT Borava Khargaon M.P.,India 2 Sanjeev S Chouhan Prof Mechanical engineering Dept. & JIT Borava Khargaon M.P.,India

Abstract— Advancement in the automobile technology reduces lots of human efforts to drive a four wheeler vehicle. The mathematical and logical calculation implementation in a research will increase the performance and efficiency of a design that may be use to get an optimized output from the system. Here in this research paper we are trying to represent the performance analysis of power steering system and its value analysis at various stages for achieving a perfect error free and effortless driving. Power steering system follows various terms to a control and drive the given input to the vehicle. Here in this paper we will discuss all those points that will help us to understand the whole system and the efforts that can be increase the efficiency of the power steering system. Keywords—Power Steering, CAN, CPU, EPHS, PSI, RPM, AI

Advance steering system main helps to drive steer vehicles by human steering effort to the steering wheel. There are basically some actuator assemblies that may hydraulic or electrical which will add controlled energy to the mechanism. So there is very less human efforts is required for driving or turning the car steering. Power steering provides feedback of forces acting on the front wheels to give an ongoing sense of according to the wheels is interacting with the road. Power steering system can be controlled using an hydraulic actuator which is a part of servo system .[1]These system have some direct mechanism have mechanical connection between the steering wheel and contact between steers wheel known as linkage that steers the wheels. The power steering system failure will switch to manual mode. Power steering system have a wire connection that means there is no direct mechanical connection to steering linkage this is called drive by wire this all assembly is drive by electricity which contains power data and feedback signals. The Power Steering Model that we have studied for advance car is a combination of both types hydraulic and electrical power steering .This combination will provide highly precise output with less effort so that the driver should make lots of effort to drive the vehicle or turn it. This model uses lots of sensors and Microprocessors (CPU) to control this whole unit from a centralize point. Most new vehicles now have power steering, owing to the trends toward front wheel drive, greater vehicle mass, and wider tires, which all increase the required steering effort. Heavier vehicles as common in some countries would be extremely difficult to maneuver at low speeds, while vehicles of lighter weight may not need power assisted steering at all.

I. INTRODUCTION The power steering system is system that used to drive or turn the four, six wheeler vehicles with very less human efforts so that the driver can drive, turn & control his vehicle for a long time with good accuracy.The power steering system mainly contains a steering wheel that wheel is connected with the shaft this shaft is then connect with the electronics system this system works according to position and torque sensor activity, this output will used to turn the vehicle in a preferred direction using a dc motor. Here in this system we are using CAN bus, Microprocessor system and lots of AI (artificial intelligence) algorithms to achieve a perfect and hard real time output without delay, for that the power steering system uses various types of high sensitive sensors to process the given input and take the proper action. The turning direction is decided according to the given input at steering wheel is decide by the position and torque sensor in nanoseconds and this information is transmitted toward the CPU(central processing unit) of the system using the CAN(control area network) bus. The CAN bus is a system bus that is used to connect various electronic component of power steering system. This bus will continuously check the all the connected sensors and microprocessor for any given signal.

II. TECHNOLOGY ADVANCEMENT Technology development in the field of steering system is been held from April 3, 1900 for the first four wheel drive system, this is the first system which uses a steering assembly but efforts reduction technique called power steering system technology is start from year 1925 and the first practical power steering system is been developed in 417

International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 8, August 2012) year 1926 & this technology is adopted by general motors and then company were start working for the development of hydraulic & electronics power steering system[2].At initial stage of power steering development the system was only developed for the military services like tanks and other heavy vehicles because of high cost. As technology grown the cost of the power steering technology reduces so that the lots of research is possible in this field .In the time between year 1970 to 1990 the power steering field is divided into two type Electronics power steering system and Hydraulic power steering system. These both type of power steering system is mainly used to reduce the human efforts as well as provide a high accuracy and precise output. A fail safe circuit is been researched and implemented into the power steering system after the year 1990, this system provides the safety and if the main system fail then this system were jump to the manual mode. When the development goes in the field of electronics and microprocessor the accuracy possibility at low cost is possible and concept of real time is achieved. There lots of things is use in the power steering system like

worm on the motor shaft meshes with the gear on the steering shaft. The gear ratio is 22:1. The gear body and the worm are made of metal. The gear ring is manufactured from plastic to reduce mechanical noise. (e) Steering column electronics control unit:-This control unit is mounted in a frame which is bolted to the housing of the worm drive. Five non-interchangeable connectors are attached to the terminal strip of the control unit by clips. The control unit calculates the steering assistance required from the data from the sensors, making allowance for road speed. (f) Electro-mechanical power steering motor:-This motor is bolted to the housing of the worm gear by means of rubber buffers so that no vibrations can be transmitted between the motor and steering column. The motor shaft is connected to the worm shaft via a flexible rubber coupling in such a way that motor starting torque is transmitted softly to the worm gear. The motor itself has a maximum power consumption of 720 W and develops 2 Nm of torque. It has an extremely short response time which allows it to assist steering wheel movements quickly.

(a)Power Steering Servo Value:-These servo values are mainly used in the steering column or directly into rack and pinion. [3] Servo value is developed after the year 1990 these are available in three types (light, medium, and heavy) can be tuned to suit the driver’s preference by means of a system of interchangeable torsion bars. The bars control the sensitivity of the power steering response and can be switched in the field without disassembly of the servo. A second revolutionary feature allows external adjustment of the left-to-right balance of the power steering.

(g) Restart protection:-The EPHS Electrically Powered Hydraulic Steering features a restart protection after a fault, failure or crash. The restart protection, if activated because of a crash, can only be deactivated with a diagnostic tool. If other faults exist, the restart protection can be cancelled by switching the ignition off and starting the engine again. It may be necessary to wait about 15 minutes in order to allow the engine pump assembly to cool down after having overheated.[4] If, after this waiting period, it is still not possible to override the restart protection by starting the engine, this indicates there is a fault in the vehicle electrical system or the engine pump assembly is faulty. In such cases, it is necessary to conduct a self-diagnosis and, if the engine pump assembly is faulty, to replace it.

(b)Power Steering Pumps:-This feature allows the mechanic to fine-tune the pump volume to match the quickness of the steering. Power steering pumps are made to precision tolerances and will produce a remarkably constant volume over the entire RPM range of the engine.

III. PERFORMANCE ANALYSIS (c) Hydraulic Assist Cylinders:-since 1989 and continually improved since, these lightweight double-acting cylinders bolt rigidly to the rack housing with four symmetrically located sockets head cap screws. The thrust is absorbed independently of the bolts by a 9/16 dowel. A thick nonmetallic piston prevents metal-to-metal contact in the bore and contributes to the very long useful life of these parts. These cylinders are tested to 1800 PSI in both directions.

Power Steering hydraulic system:The fluid pump is directly driven by the engine through a belt. The fluid flow is maintained almost constant regardless of change in the engine speed by the function of the flow control valve. The flow-regulated fluid is delivered to the control valve through hose A. When the steering wheel is turned, the rotary control valve connected to the pinion shaft opens the hydraulic circuit corresponding to the direction in which the steering wheel is turned.

(d)Worm gear:-The worm gear is located in an aluminium gear case where the electric motor is also mounted. A 418

International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 8, August 2012) The fluid then flows into chamber A or B via pipe A or B. The fluid pressure in chamber A or B acts on the rack piston in the same direction as that in which the rack shaft is moved by rotation of the steering wheel. This helps reduce the effort required of the driver to operate the steering wheel. Movement of the rack piston causes the fluid in the other chamber to return to the reservoir tank via pipe A or B, control valve, and hose B.As the steering shaft is connected to the pinion shaft mechanically via the rotary control valve, the steering system can operate as a manual system even if the hydraulic system becomes inoperative. To control the maximum fluid pressure, a relief valve is built into the fluid pump to prevent build up of an excessive fluid pressure.[6]

Rotary control valve:The rotary control valve consists of a rotor (which rotates together with the steering shaft), a pinion (which is connected to the rotor and torsion bar), and a sleeve (which rotates together with the pinion). The rotor and sleeve have grooves C and D, respectively, which form fluid passages V1 through V4.The pinion is in mesh with the rotor with adequate clearance, which enable the rack to be moved manually by rotating the steering shaft (fail-safe feature).

Fig 1:- Power steering hydraulic system [6] Fig 2:-Rotary valve Internal design [6]

(1) Power cylinder (2) Rack piston (3) Rack shaft

When the torsion bar is twisted by a rotational force applied to the steering wheel, the relative position between the rotor and sleeve changes. This changes the crosssectional area of fluid passages V1, V2, V3 and V4. The fluid passages are thus switched and the fluid pressure is controlled in accordance with the operation of the steering wheel. When no steering force is applied: The rotor and sleeve are held at the neutral position. Fluid passages V1, V2, V3 and V4, which are formed by grooves C and D are open equally. Under this condition, the fluid from the pump returns to the reservoir tank so that neither fluid pressure builds up nor the rack piston moves in the power cylinder.[6]

(4) Pinion shaft (5) Chamber A (6) Chamber B (7) Pipe A (8) Pipe B (9) Control valve (10) Steering shaft (11) Steering wheel (12) Tank (13) Vane pump (14) Relief valve (15) Hose A (16) Hose B (17) Pump control valve (18) Fluid pump (19) Engine

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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 8, August 2012)

Fig 3:-Power Steering Piston Movements [6]

IV. VALUE ANALYSIS An electro-mechanical power steering system and a hydraulic system have totally different modes of value analysis By comparison: The specifications emphasis the difference. Hydraulics Electromechanical system Weight 16.3 kg 11.3 k Power consumption Urban cycle Motorway cycle Additional consumption compared to mechanical steering gear in litres per 100 km

400 W

25 W

800 - 1000 W

10 W

0.1l *

0.01 **

* referred to 44 KW SDI engine

** referred to Lupo 3L with 1.2l TDI engine

Figure 4:-Steering wheel torque as a function of lateral acceleration.[5]

Here in the figure 5 we saw the performance graph and its value and pressure or load on the power steering at different driving points, as shown in the graph during the parking the power steering requires more load and less load on highway driving.

Figure 5:-Boost Curve with different working areas depending on the driving envelope.[5]

Here in the figure 4 we saw a comparative graph steering wheel torque and lateral acceleration here an exponential change in the sensitivity of steering wheel torque increase with increase in the acceleration this means that as the speed of vehicle increases less amount of toque is required this graph value is set with the processor of providing exact and accurate output according to input.

V. CONCLUSION “The world of automobile turns around by means of power steering”. The value and performance analysis in this paper will help to understand the error as well as this data can be use to increase the efficiency of power steering . 420

International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 8, August 2012) There are still lots of possibility to make steering system more easy and effortless and this paper will help to provide a helpful thinking in that way. Power steering systems have been a proven technology for decades; there are still problems to be solved, most concerning quality issues. In this thesis, two predominant problems have been studied, hydraulic lag and the chattering phenomena. Power steering made vehicle driver smooth and effective driving in this paper we consider the part of automobile i.e. steering and how it works in terms of performance and values. REFERENCES [1] Introduced industry first power steering Magazine [2] www.time.com/time/magazine/article [3] power steering system components by wood-ward precision power steering

[4] www.volkspage.net/technik/ssp/ssp/SSP_225.pdf self study program 259

[5] Power steering system design by marcus rosth [6] W1860B E.book on power steering system

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