DESIGN OF MODIFIED STEERING SYSTEM AND

DRIVE MECHANISM FOR TURNING WHEELS

THROUGH 90 DEGREE

Abstract - In this paper, an effort is made on the development of steering and drive mechanism which will result in turning of wheels by 90-degree and also to develop automatic and less costly vehicle. The approach is to construct a vehicle which can turn through any angle. This paper focuses on steering model consists of worm and worm wheel gear set at each wheel which can turn the vehicle at grater angles and at less effort. The steering model in this paper also using chain and sprocket to transfer the motion from dc motor to each shaft which is located at front and rear of the vehicle. Primary objective is to use our vehicle for carrying industrial load on the industrial floor. The reason is space limitation in industries as turning radius is reduced to minimum. Worm and worm wheel gear set is used because speed reduction is of greater advantage than any other gear set. This designed vehicle is automatic to drive as well as to steer. This type vehicle can easily eliminate extra workers to drive in industries thus for industrial purposes it is cost effective and can work at any working condition. Mostly used steering system have movement limitation to such a larger angles and some research papers have also published model of electric vehicles having steering movement larger than 90 degrees but the whole mechanism is dependent on chain drive which is not as efficient as steering movement obtained from worm and worm wheel gear set. some other research papers have steering models having manual steering control with a steering movement of greater than 90 degrees but these types of vehicles have negligible space for suspension system and these vehicles requires man power for control that's why these are not cheaper option for industries or anyone. Because of compact design of this model there is enough space available for suspension system, cost effective and obtaining larger steering angles at smaller steering effort.

1 INTRODUCTION

The conventional steering arrangement is to rotate the front wheels using a hand-operated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal joints to allow it to deviate somewhat from a straight line. Main function of the steering system is to achieve angular motion of the front wheels to negotiate a turn. This is done through linkage and steering gear which convert the rotary motion of the steering wheel into angular motion of the front wheels. For decreasing the turning radius and increasing the turning angle of wheels of vehicles for transverse parking various mechanisms are proposed one after another, some seemed to inspire but most of them failed to get commercialized. Some electric carsare powered with a lithium-ion battery, the wheels have been moved to rotating pods that allows the car to drive the car in any direction. Along with the rotating cabin, this allow the car to pull up next to a parking space, the wheels and cabs simply rotate 90 degree and the car drives in sideways. Each wheel contains a motor for transmitting power in individual. Several other mechanisms were proposed for decreasing the turning radius

of automobiles for better parking at confined spaces.

Four-wheel steering system is a system used by some vehicles to improve steering response, increase vehicle stability while manoeuvring at high speed, or to decrease turning radius at low speed.

In most the currently used four-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the front wheels. Some systems, including Delphi's Quadra steer and the system in Honda's Prelude line, allow for the rear wheels to be steered in the opposite direction as the front wheels during low speeds. This allows thevehicle to turn in a significantly smaller radius, sometimes critical for large trucks or vehicles with trailers. An electronic four-wheel steer system is an option available on the JCB Fastrac.

The mechanism due to which the rear wheels turn counter steer at low speeds and same direction at high speeds can be controlled electronically or hydraulically. The Japanese automakers have come up with this technological solution. Example: Mazda's 626 four-door sedan turns its rear wheels electronically. Sensors monitor the car's speed and its front-wheel angle and pass the information to an onboard computer, which determines in what direction the back wheels should turn. At speeds less than 22 mph, the rear wheels counter steer; at more than 22 mph, their turn version is simpler but more limited.

Worm gear and pinion arrangement based steering mechanism is used in this paperfor designing vehicle. Worm gears are used to transmit power at 90°, Compact gear boxes and worm gear arrangement were used for every individual wheel. They used four motors and gear boxes for individual wheel which drive the wheel. In order to provide angular motion i.e. 90 degree in the wheels they used worm gear arrangement. While for rotating the wheel, they used two separate Geared motors.

2. CONSTRUCTION1) Motor

The 12V DC motor is used for running the vehicle. The system consists of 2 DC motors are used for running the four individual wheels of the vehicle and the rest two motors are used in chain drive system for turning of the wheels of the vehicle.

Arun Kumar, Ashutosh Singh Chauhan, Aditya Tyagi, Ashwani Rathore, Anshul RathiME, ABES Engineering College, Ghaziabad

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3. WORKING

In this project turning of wheels at any angle is achieved by our designed steering mechanism. We are going to use total three DC motors one motor is used to move the chain and sprocket. Other two DC motors are used to rotate the wheels of vehicle. Chain and sprocket move two shafts placed at front and rear end of vehicle these two shafts are connected with worm and worm wheel gear set. These gears set transfer motion at 90 degree to each wheel which is required for turning or steering of our vehicle.

4.CALCULATIONS1) Chain sprocket calculation: -Mass of vehicle = mass of body + weight which can be placed on body

= 10 + 5

= 15 kg

Load or weight due to vehicle =15 × 9.8 =147 NMass is uniformly distributed, so the weight on single wheel = 147/4 = 36.75N

Static friction on each wheel (Fs) = µN

µ for dry road and wheel is 1 = 36.75 N

Initial rotating velocity of wheel (Wi) = 0 rad/sec

Since, (Ɵ = π/2)

Assume time to rotate = 5 sec

Ɵ= Wi × t + 0.5 × α × t2 ؞

α = 0.125 rad/sec2

Torque (Ʈ) = Fs × r + I × α

Where, r = perpendicular distance of wheel centre from rotating rod.

I = moment of inertia of about rotating axis or rod.

Assume r = 2cm = 0.02m

I = mr2 = 0.2 × 0.022 = 0.00008 kgm2

Mass of single wheel = 200 gm

Ʈ = 36.75 × 0.02 + 0.0008 × 0.125 = 0.73501 Nm

(Wf)2 = (Wi)2 + 2 × Ɵ

Wf = 0.6266 rad/s

Take maximum omega for calculating rpm of rod.

i.e. Wf = 0.6266 rad/sec

W =(2πn)/60

n = 5.94 rpm

Velocity ratio = (10/2) [ Taken from worm gear calculation]

N (worm) / N(worm gear) = 10/2 ؞

N (worm gear) = n of rod = 5.94 rpm

N(worm) = 5 × 5.94 = 29.7 rpm

Rpm of worm = rpm of sprocket

N of sprocket = 29.7 rpm ؞

2) Wheels-

The wheels are used for the motion of the vehicle and each individual wheel in the vehicle is controlled by the individual DC motor which is run by the battery. Thus, the wheels of the vehicle are run by using electric power.

3) Chain and Sprocket-

Here chain and sprocket mechanism is used for turning the wheels of our vehicle at required angle. This chain rotates shaft at front and rear end with the help of sprocket and motor.

4) Frame

frame is used to bear all the weight and vibration on the vehicle.Itis also able to hold extra weight for which the vehicle is designed.

5) Worm and worm wheel gear set-

It is used to transfer motion at an angle of 90 degrees. It is also used for velocity reduction. These gears are only responsible for turning of wheels at any angle.

Design of modified steering system and drive mechanism for turning wheels through 90 Degree

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Design of Worm

Assume velocity ratio = 10:2, and centre distance = 27.05

cot3 ƛ = V.R = 5

ƛ = 30.319°

xln = (1/2π) × (1sinƛ+ V.Rcosƛ)

ln = 21.865

axial load, L = ln/cosƛ = 25.329

n = 4 (quadruple)

Axial pitch, Pa = L/4 = 6.3325mm

Module = Pa/π =2.0156 =2 (approx.)

Now, Pa = Pc = π m =6.2831 mm

L = 4 Pa =25.1324 mm

Ln = L cos ƛ =21.694 mm

Ta = 5×4 =20 teeth

Depth of tooth, h = 3.914

Addendum, a = 0.286 Pc = 1.7969 mm

Dw = L/(π tanƛ) = 13.679mm

Do w = 13.679 + 2a =17.278 mm

4)Design of Worm Gear

Teeth = 5×4 = 20

Diameter (Da) =m×Tg = 2×20 =40mm

Do G = DG + 0.8903 Pc = 40 + 5.593 = 45.5938 mm

b (tou width) = 2.15 Pc + 5mm = 18.508mm

# Power ratio of chain = KW to transmit ×KsK1 ×K2

Now KW to transmit to single wheel = (2 π n Ʈ)/ (60 ×1000) = (2 π ×5.94 ×0.73501)/ (60000) = 0.457 KW

Total power to be transmitted = 4 × 0.457 KW = 1.828 × 10-3 KW

Now from V B Bhandari: -

Ks = 1, K1 = 1, K2 = 0.55 [for Zdriving = 10]

We take Zdriving = 10 as speed or rpm of sprocket is very low.

KW rating of chain = 1.828 × 10-3 ×11 ×0.55 = 3.323 × 10-3KW ؞

Now, Ns = 29.7 rpm

Zs = 10 teeth

From above rating of power, we can choose 10(ANSI- 50) chain.

p = 15.69 mm ؞

D = p / {sin(α/2)} = 15.69 / {sin (2 π/ Z × 2)} = 50.8 mm

For this chain-

Roller diameter (d1) max = 10.16 mm

Width b1 min = 9.4 mm

Length of chain (T) = 2 × 9 ×25.4sin45 + 18 × 25.4 + D2×Ɵ2180 × 2 + D2×Ɵ1180

Ɵ2 = 135, Ɵ1 = 90

T = 1263.36 mm

Links(L) = Ln × p

Ln = 80 links

2) Sprocket calculation

From VB Bhandari, p = 15.69 mm

D =50.8 mm

(Da) max = D + 1.2P p-d1 = 60.25

(Da)min = D + p{1-(16/z)} – d1 = 53.819 mm

Df = D – 2ri

(ri) max =0.505 d1 = 0.069 d11/3

(ri) min = 0.505 d1

(ri) max = 5.280 mm

(ri) min = 5.130 mm

(re) max = 0.008 d1 (Z2 + 100)

(re)min =0.12 d1 (Z + 2)

(re) max = 22.758 mm

(re) min = 14.630 mm

(ha) max = 0.625 p – 0.5 d1 + (0.8p/2)

(ha) min = 0.5 (p –d1)

(ha) max = 5.981 mm

(ha) min = 2.765 mmbf1 = 0.95 b1 (if p > 12.7)

Vision & Quest, Vol. 9, No. 2, Jan.-June 2019ISSN: 0975-8410

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Assembly

REFERENCE

1) Vishal Dhumal1, Dube

ndra Yewale2, 90 Degree Steering System 1Professor, Dept. of Automobile Engineering, Dr. D Y Patil SOET, Pune 05 | May 2019.

2) Ravi Shankar*, Kumar Saumya, Fabrication of modified steering and drive mechanism for turning wheels through 90 degree in parallel parking,*Research Scholars, Department of Mechanical Engineering, Amrapali Institute of Technology & Sciences, Haldwani, India, ISSN No. (Print): 0975-8364

3) Arjun V Pradeep,Jijomon Joseph,Harikrishnan S,90 Degree Steering Mechanism,UG Student, Department of Mechanical Engineering Saintgits College of Engineering, Kottayuam, Kerala,IJIRST –International Journal for Innovative Research in Science & Technology| Volume 2 | Issue 11 | April 2016

4) ��. ����������, Design and Fabrication of Four wheel 90 Degrees Steering System for Advanced ParkingPG Scholar, Department of Mechanical Engineering, Gnanamani College of Technology, Namakkal, Tamilnadu, IndiaIJARIIE-ISSN(O)-2395-4396.

5) M Suvarna, M Poojitha, T. Nikitha 90 DEGREES STEERING MECHANISM Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-5, 2017

6) International Journal of mechanical engineering & robotics research, National conference on “Recent advances in Mechanical Engineering” RAME -2013, Vol. 1, No.1, January 2014.

7) Three dimensional modeling and dynamic analysis of four-wheel-steering vehicles”, Journal Acta Mechenica Sinica, Publisher: Springer Berlin / Heidelberg, Issue, pp. 79-88, Vol. 19, No. 1, February 2003

8) A textbook for Machine Design Book by V.B. BHANDARI.

9) A text book for Automobile Engineering by Dr. Kirpal Singh

10) A text bookfor Theory of Machine by R.S. KHURMI

Design of modified steering system and drive mechanism for turning wheels through 90 Degree

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