A New Approach on Differential and Variable Speed Braking System for Vehicles

Transcription

1 A New Approach on Differential and Variable Speed Braking System for Vehicles Ron Prodhan, Rahul Yadav Students (B.Tech), Department of Electronics and Communication Engineering, Institute of Engineering and Management, Salt Lake, Kolkata , West Bengal, India. Abstract- We have tried to design a braking system that can be controlled by the user as well as by a system. This system will be able to reduce the speed of the car to any speed desired by the user as and when it is required. The system will be able to generate voltage which can be used to charge the battery of the vehicle. This would not require any additional cost as it is an integral part of the main system. The braking system when system controlled will have the ability to take steeper turns at high speeds, and will ensure better traction control of the vehicle. This will be done by differential braking magnitude applied to different wheels. Keywords: Solenoid coils, differential brakes; Comparators; Variable speed brakes. I. INTRODUCTION Hydraulic and pneumatic brakes used in today s vehicles, especially those manufactured in twenty first century mostly- mechanical or electromechanical system. They are designed to work in absence of any trigger given by the car itself; also the magnitude of speed reduction is also constant, that is a continuous application of brakes for a long period of time would result in the speed of car being reduced to zero. The conventional braking system is not equipped with the ability to reduce the speed of the vehicle to a fixed speed specified by the user or the system. Thus for a system where the user does not want to increase his speed above a desired speed or the user wants to reduce his speed to a desired speed using a switch, it is not possible for user with the conventional braking systems. The kind of flexibility and rigidity required in braking for various environments is absent in the conventional braking systems and it depends purely on the user s conscience, consciousness and effective analysis of the environment. Moreover an added disadvantage is that the user has to apply brakes by pressing the clutch and then the brake. This is relieved in by few companies such as Tata Marcopolo bus where the user has to press only the brake pedal and the clutch pedal is absent. This is highly recommended for a system where the user intends to apply brakes using a switch that is an electromechanical system. Moreover a system controlled brake would require large solenoid valves along with hydraulic pumps. Along with this, a conventional braking system does not allow the user to provide differential brakes on all different wheels that is magnitude of applied brakes is uniform in all four wheels. HYDRAULIC BRAKES The most common arrangement of hydraulic [6] brakes for passenger vehicles, motorcycles, scooters, and mopeds, consists of the following: Brake pedal or lever A pushrod (also called an actuating rod) A master cylinder assembly containing a piston assembly (made up of either one or two pistons, a return spring, a series of gaskets/ O-rings and a fluid reservoir) Reinforced hydraulic lines Brake caliper assembly usually consisting of one or two hollow aluminum or chrome-plated steel pistons (called caliper pistons) A set of thermally conductive brake pads and a rotor (also called a brake disc) or drum attached to an axle. Disadvantages of hydraulic brakes are given below: ISSN: Page 30

2 Sometimes fluid makes the system useless when slight leakage. For intermittently brake the hydraulic system is suitable to be applied. Hydraulic pumps are required if the same has to be automated Cannot be applied differentially. This is the house arrangement of the proposed system which will hold the permanent magnets of the generator system. The ferromagnetic plates used in proposed braking system will be useful for two main purposes: This will reduce the leakage of magnetic lines of force and help the generator coil to generate more voltage. Reduce the influence of magnetic force [1] of the vehicle s wheel on the adjacent car. II. PROPOSED SYSTEM WITH DIFFERENTIAL BRAKING For any conventional automobile equipped with manual transmission the user has to apply clutch to cancel the transmission from the engine and then the brake is applied. The auto transmission vehicles provide the user the ability to apply brakes without applying clutch. The differential braking system, as proposed, will provide the user or a corresponding microcomputer system the ability to brake without involving any mechanical system. The design will also help the user to reduce the vehicle speed to the speed desired by him. The system will include the following parts: A. Generator System Figure 2. Magnets positioned in the wheels (Total eight magnets in 450 apart) The system will have the following arrangement in all the wheels. Figure 3. Magnets positioned in the wheels (side view) Figure 1. Wheel Housing Diagram As the wheel rotates, the rotating magnetic field will generate an electromotive force (emf) on the four generator coils attached to the fixed casing and placed at 90 0 apart. The emf generated is directly proportional to the wheel speed. The arrangement has been shown in Fig 3. ISSN: Page 31

3 It will check the rpm of the concerned wheel of the vehicle It will reduce the rpm to that required by user or system The electronic control system will essentially consist of three parts: 1) Feedback And User Control Figure 4. Generating Coils This part of the system is attached to the generator coil. It receives the generated voltage from the coil after attenuation and compares it to the voltage required by the user. Since the generating voltage is directly proportional to the wheel speed (rpm) [5], the change in wheel speed (rpm) will result in a change in the generated voltage. This voltage will be used in the process of applying brakes in the vehicle. The generated voltage will be compared with a reference voltage (set by the user depending upon the speed desired) in a comparator to generate an error signal. The error signal so produced will trigger the brakes in the respective wheels. The voltage so produced can be used for charging batteries of the vehicle. Figure 6. Generated Voltage Attenuator The Attenuator gives an output proportional to the input generated voltage. Figure 5. Side view of Generating Coils arrangement on the Axle This is the front view of the arrangement of the generating system excluding the magnets. B. Electronic Control The electronic control in this system will be responsible for two main purposes as follows Figure 7. Feedback Comparator Since the generated voltage is directly proportional to the number of revolutions per minute (rpm), the user or system may provide the desired rpm in terms of voltage(vr). The difference in the ISSN: Page 32

4 feedback voltage and the voltage required by user will result in an error signal [3] required to activate the braking control. The error signal will result in the following changes in the car: Switch off fuel supply Switch off the ignition Clutch disengaged Brake controls activated The car will be in its inertia for the brakes to be applied. 2) Differential Control While taking a left or right turn, this system can control the speed of the inner and outer wheels of the vehicle separately using the steering position of the vehicle. In the steering there are two potentiometers for left and right side (as shown figure 8), whose values can be changed while taking a turn as and when desired. Figure 8. Potentiometer For Differential Braking For example, while taking a right turn when we turn the steering towards right the resistance on the right side of the steering increases as a result the speed of the two inner wheels( in the right) decreases compared to the two outer wheels(in the left), similar procedure is followed when we take a left turn. In this way we can control the speed of the inner and outer wheels of the vehicle while taking a turn(left or right). The output is then fed to an amplifier whose gain depends on the potentiometer output. Figure 9. Amplifier The output of the amplifier determines the magnitude of braking applied on different wheels. 3) Braking Control The braking control will send a current through the brake coil. The current will result in a magnetic field. The current will be changing its direction that is it is alternating. This will be done using a pulse generator [4]. The pulse generator will produce a peak and zero volt. The pulse generator will produce a high output when South Pole of the magnet faces inwards and North Pole of the magnet faces outward. This will be done using a laser diode and light dependent resistor along with a perforated plate arrangement. The plate is perforated at the points where South Pole of the magnet faces inwards. This arrangement will synchronize the frequency of the alternating current to that of the wheel. This will keep the force of attraction prevalent, for the entire duration of braking. This is then sent to a voltage to current converter which will produce a positive and negative cycle current depending on the duty cycle of the pulse generator which can be adjusted. ISSN: Page 33

5 Figure 10a. Pulse Generator (HIGH PULSE GENERATED, FRONT VIEW) Figure 10d. Pulse Generator (HIGH PULSE GENERATED, SIDE VIEW) Figure 10b. Pulse Generator (LOW PULSE GENERATED, FRONT VIEW) Figure 11.. Pulse Current Generator The alternating current so produced will result in the braking as described in the next section. C. BRAKING SYSTEM The braking system employed in the proposed braking system will be a non contact type braking system. It will not employ any kind of friction to brake the car. This will reduce the maintenance cost on brakes. Figure 10c. Pulse Generator (HIGH PULSE GENERATED, SIDE VIEW) ISSN: Page 34

6 Figure 12. Arrangement of Braking coils The braking system will be placed adjacent to the generating coil on the static casing. The coils will be made on a soft iron core which will produce a magnetic field when a current passes through it. This field which will exert a force of attraction on the magnets attached to the rotating wheel. The force of attraction so produced will oppose the motion of the wheels. This will result in the reduction of the number of revolution per minute (rpm) of the wheel. Figure 14. Braking coil arrangement on axle( side view) The braking coils are separated from generating coils to prevent any effect of the magnetic flux produced by braking coils on the generating coils. Figure 15. Side view of the total wheel arrangement III. CONCLUSION Figure 13. Braking Mechanism The force of attraction so produced will have an additional advantage that it will prevent the casing from colliding with the axle shaft. Hence the choice of the force of attraction over the force of repulsion is taken. Therefore the direction of current is continuously alternated so that the polarity of the solenoid coil is opposite to the polarity of bar magnets. This system can be used to create a advanced automobile system for better traction control, speed control and stability control. This system can be used to prevent over steer and under steer of vehicles in very high speed. The best part of this system is that it uses each and every wheel to generate voltage which can be used for charging the batteries of the vehicle. An added advantage of this system is that it stops fuel consumption of the vehicle when the user wants to brake. This makes it suitable as a eco-friendly system. The most important part is that the system can be used along with other systems to bring about necessary modifications in automobiles. ISSN: Page 35

7 Acknowledgement We would like to give our sincerest and heartiest thanks to our mentor Prof. Gautam Ghosh for his support,encouragement and invaluable detailed advice on grammar, organization, content, and the theme of the paper. We would like to thank our parents for their constant support in this endeavor. References [1]L.SULLIVAN STEVEN, DELOS AEROSPACE LLC, Patent No: US Landing gear method and apparatus for braking and maneuvering; Date: [2] Electromagnetic brake, Wikipedia, en.wikipedia.org/wiki/electromagnetic brake. [3] A. S. Sedra and K.C. Smith, Microelectronic Circuits, Oxford University Press, India, 2013 [4] D. Roy Choudhury and Shail B. Jain, Linear Integrated Circuits, New Age Techno Press, India, 2013 [5] B.L. Theraja, - A Textbook of Electrical Technology, S.Chand & Company Pvt. Ltd. India, [6] Hydraulic Brakes, Wikipedia, ISSN: Page 36