Automatic Jack with Inflator and Electric Wrench

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1 IJIRST International Journal for Innovative Research in Science & Technology Volume 2 Issue 11 April 2016 ISSN (online): Automatic Jack with Inflator and Electric Wrench Degin John Jibin P. John Jeffin James Jibin P. Philip Philip Jacob Perakathu Assistant Professor Abstract When it comes to travelling by cars, mishaps and unwanted incidents such as tyre puncture, low air pressure in tyre are extremely common. A conventional carjacking system makes use of mechanical advantage to lift the cars. Despite the mechanical advantage jacking up a car is a very difficult task for many people especially women and elderly people. The objective of this project is develop a new carjacking system in order to make the operation easier, safer and more reliable in order to save individuals from unnecessary expenditure of energy and reduce health risks especially backache problems. In the context of this particular project, the newly developed scissor jack uses a 12 V DC motor as the prime mover which works using the car battery. The motor is connected to the lead screw of the jack through reduction gear, so as the motor starts, the pinion is rotates with a torque equal to the motor torque. Since the pinion is in mesh with the gear (double the number of teeths in pinion) in the lead screw, the driven gear starts rotating with a multiplied torque, thereby lifting the car. The developed system also has a provision for inflating the tyre, which is used when the air pressure in the tyre is lesser than ideal conditions. The system uses a reciprocating type compressor which works on the 12 V supply. The main advantage of this system is that we can use it whenever we requires. Keywords: Compression ratio, Gear ratio, Helix angle, Lead screw, Pinion I. INTRODUCTION Toggle jack is used to jack the car during side road emergency i.e. tyre puncture. A mechanical jack is a device used to lift all or part of a vehicle above the ground in order to facilitate vehicle maintenances or repair in the event of a breakdown. Changing a flat tire is not a very pleasant experience. Nowadays, a variety of car jacks have been developed for lifting an automobile off the ground. Available car jacks, however, are typically manually operated and therefore require substantial physical effort on the part of the user, making it s usage all the more difficult for the elderly and handicapped. It further requires the operator to remain in an uncomfortable bent or squatting position for extended durations of time while operating the jack. Doing work in a bent or squatting position for long periods of time is not ergonomic and convenient, nor is it a healthy practice. It will most likely result in a severe backache problem in the long run. A toggle jack is operated by means a lead screw. In this type of jack, a small force applied in the horizontal plane is used to raise or lower large loads. This project aims at developing a technology that could potentially replace the aforementioned mechanical jack by combining the effectiveness, comfort and ease of operation of an electric jack while keeping in mind the size constraints which dictate the portability of the newly developed jacking system. The specified jack is designed to withstand a maximum load of 1000 kilogramsthe standard weight of an average car used in India (taking into account the appropriate safety factors). A wide spectrum of tests undertaken by consumer affairs have revealed that most mechanical jacks are unreliable and tend to fail over time when loaded close to 1000 kilograms. Tests have proven that the jack has the tendency to buckle under the weight it is subjected to withstand. The purpose of this project is to develop a car jack which can be easily operated by the user at the minimum use of power and effort while ensuring the design is portable enough to be carried around by an average person during his or her travel. All rights reserved by 379

2 II. DRAWBACKS AND LIMITATIONS OF CONVENTIONAL SYSTEMS The most common method of overcoming unforeseen circumstances such as flat tyres and replacing them with spares can be a tedious and somewhat difficult process for people who are not experienced in such matters. Besides the conventional method of lifting a car and replacing the flat with a spare can also be a waste of energy. This project mainly aims to develop an alternate system of replacing flat tyres that can overcome the drawbacks of the conventional system, such as: - The conventional method of replacing flat tyres is a very time consuming process since it is done manually. - The conventional method of replacing flat tyres is difficult to do for a single person. - The conventional method is person dependent the ease with which the process can be carried out is dependent on the skill and experience of the person carrying out the operation. - It requires large amounts of physical strength that may prove challenging for females, elders and differently abled people. - The present system requires a spare tyre to be present mandatorily, however the developed system can be used to temporarily fill the tyre with compressed air such that it can be used till a gas station can be reached and professional help is obtained. III. DESIGN AND DEVELOPMENT OF THE SYSTEM 1) The ground clearance of the vehicle is assumed to be 165 mm. (Decided on the basis of detailed studies conducted regarding various car specifications.) 2) When the screw jack carries the maximum load, i.e. when the wheel of the vehicle leaves the ground, the screw jack is assumed to have moved in the vertical axis (linearly) by a distance of 50mm. (Decided after practical observational analysis of conditions.) 3) The screw jack supports a quarter of the total vehicle mass, which is approximately 300 kg, i.e N of force of car of weight 1200 kg i.e N. Considering possible fluctuations during operation, weight is taken as 500 kg i.e N. Condition Derived for Initiating Design: Input parameters are decided by making a study of car specifications and various loading conditions. Some inputs are decided by practical analysis of the vehicle lifting conditions while jacking during tyre failure condition. 1) Maximum weight of car = 500 kgf / 5000 N. 2) Ground clearance = 165 mm 3) Maximum lift = 50mm Derived: Max load on jack depending on condition of road: Conditions: 1) On horizontal road surface. 2) On sloping surface. It is observed that max load acts on jack when vehicle is on horizontal surface. Angle between the links with horizontal axis (θ)show in figure 4.2 and figure 4.3 after studying the toggle jack brought from junk yard: Angle in upper position (θ max ): tan(θ max ) = θ max = Angle in lower position (θ min ) All rights reserved by 380

3 57.5 tan (θ min ) = θ min = Total axial force on the screw, F = W/tan Ө Where W = load Ө = angle between the links with the horizontal axis Force will be maximum when Ө is minimum Force, F = W/tan Өmin = 5000/ tan (29.89) = N Calculation of torque required for overcoming the thread friction (T): Automatic Jack with Inflator and Electric Wrench The lead screw used for the present project has certain specifications. The major specifications of the lead screw are as follows Core diameter, dc = 11.5 mm Outer diameter, d = 16 mm Mean diameter, dm = 14 m Pitch, p = 14 mm For ACME thread, thread angle β = Helix angle, λ = tan -1 ( p ) = πdm tan-1 4 ( ) = π Coefficient of friction( µ \ µ ) = =.15 = cosβ cos14.5 Friction angle Φ = tan - 1(µ / ) = tan - 1(0.154) = Effort required to rotate the screw p = F tan(λ+φ) Required torque, T f = p dm 2 = tan( ) 2 tan29.89 = Nm Efficiency of threads(η) = 1 sinφ 1+sinΦ =1 sin9.80 = 73.46% 1+sin9.80 Actual torque required T = Motor Selection: Tf η = = Nmm The motor used is a salvaged bus wiper motor. The calculated value for the torque according to the manufacturer is 13 Nm torque which, after torque multiplication is high enough and suitable for the project. Specification of motor obtained from label on motor: 1) Brand name: Lucas TVS 2) Part no: 3SW60 3) Use: Wiper 4) Type: DC motor 5) Motor: Brush 6) Power: 60 Watt 7) Torque: 13 Nm 8) Voltage: 12 V 9) Current: 2A Condition for Initiating Design of Gear Pair: A gear is a machine member commonly used in most mechanisms and machines the main function of these rotary members being transmitting motion from one shaft to another. The shafts in consideration may have parallel axes, perpendicular axes etc. Depending on the type of motion and the relative orientation of shafts, different kinds of gears are commonly used such as spur gears, helical gears, herringbone gears, worm gears-worm wheel combinations, rack and pinion arrangements etc. There are several terminologies and dimensions/angles that define the specifications of the gear. The necessary condition for two gears to mesh is that the modules of both the gears must be the same. Module is defined as the ratio between the diameter and the number of teeth. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, torque, and direction of a power supplied from a prime mover (an electric motor in this case). When two gears mesh and one gear is bigger than the other two a mechanical advantage is produced, with the rotational speeds and the torques of the two gears varying according to an inverse relationship. Input parameters are decided after studying and understanding the parameters considering the output of motor and input available for screw of jack. And certain assumptions are considered for designing the gear pair. All rights reserved by 381

Initial Data: 1) Input torque(t1) = 13 Nm 2) Input speed(n1) = 50 rpm(obtained by testing motor) 3) Output torque(t0) = 20.65084Nm 4) Gear ratio(g) = output torque/input torque =20.

4 Initial Data: 1) Input torque(t1) = 13 Nm 2) Input speed(n1) = 50 rpm(obtained by testing motor) 3) Output torque(t0) = Nm 4) Gear ratio(g) = output torque/input torque = /13 = 2 5) Actual output torque(t2) = 26 Nm 6) Output speed(n2) = 25rpm Assumptions: 1) Number of teeth on pinion (tp) = 18 2) Number of teeth on gear (tg ) = 36 Design of Inflator: The inflator consists of a compressor and a motor. The shaft of the motor is coupled to the motor shaft to operate it as a single unit. The two types of reciprocating compressors in general use are single acting vertical compressors and double acting horizontal compressors. The single acting compressors usually have their cylinders arranged vertically, radially or in V form. Motor Selection: The motor has been obtained from the junk yard and it is basically a bike starter motor. From the manufacturer and calculated value for the power, is 240 watts which is high enough and suitable for the project. Specification of motor obtained from label on motor: Speed = 1500rpm Current = 20A Voltage = 12V Power = 240W Compressor Selection: Generally the tyre pressure of vehicles is about 2-3 bar ie about 40 Psi. So we have used a compressor with output pressure greater than 40 Psi. Compressor Specifications: Motor speed = 1500 rpm Bore diameter = 20mm Stroke length = 18mm Clearance space length = 3mm Pressure Calculation: Assuming that compression is isentropic. The various processes in the working of a compressor is, Process 4-1 Suction (isobaric) Process 1-2 Compression (isentropic) Process 2-3 Delivery (isobaric) Process 3-4 expansion (isentropic) The p-v relation for isentropic process is given by: P 1V 1r =P 2V 2 r Pressure P 1 = 14.7 psi (1 bar) All rights reserved by 382

V 1 = total volume = π 4 (d2 ) L = π 4 (0.02)2 (.018) =5.654 10-6 m 3 V 2 = clearence volume = π 4 (0.02)2 0.003 = 9.424 10-7 m 3 P 2 = P 1V 1 r /V 2 r = (1 105 (5.654 10-6) 1.4 ) / (9.424 10-7) 1.

5 V 1 = total volume = π 4 (d2 ) L = π 4 (0.02)2 (.018) = m 3 V 2 = clearence volume = π 4 (0.02) = m 3 P 2 = P 1V 1 r /V 2 r = (1 105 ( ) 1.4 ) / ( ) 1.4 = Bar =180 psi Calculation of discharge Mass flow rate through the system = ρ 1v 1 Density ρ 1 = P/RT = 10 5 /( ) = Kg/m 3 Speed of rotation of motor = 1500 rpm Number of strokes per sec = N/60 Mass flow rate per sec = ρ 1V 1N/60 = ( )/60 = kg/s =.1598gram/s Volume flow rate = (mass flow rate per second)/ ρ 2 Temperature T 2 = T 1 ( P1 P2 )γ 1 γ = 303(12.28).4/1.4 = K Density ρ 2 = P 2/RT 2 = ( )/( ) All rights reserved by 383

6 = 6.90 kg/m 3 So, volume flow rate =.1598/6.90 = m 3 /s The expression for work done in a reversible adiabatic or isentropic process per cycle is given by the expression γ 1 W = γ γ 1 P1V1 ((P 2 ) γ -1) P = (( ) ) 1 = Nm/min Power required to drive the compressor is obtained by the relation P = W(in N m/min) 60 = = watts watts IV. APPLICATION/ADVANTAGES - It makes tyre changing process easier for ladies, elders and handicapped people. For ladies, elders and handicapped, changing the tyres of car without any external help can prove to be a challenging and difficult task. But using this unit it is possible for them to do the process without any aid. - Decrease human effort. - Reduces the time needed for the operation. Generally a healthy person requires about minutes for changing car tyres.incase of women the estimated time is usually more than half an hour. Using this equipment the time needed for this process is reduced. The whole tyre changing process can be completed within 10 minutes. V. CONCLUSION Side road emergencies such as tyre puncture, low air pressure in tyres are commonly observed in cars. Conventional car jacks use mechanical advantage to lift the cars, but it is very difficult for the ladies, elderly and handicapped persons to operate the mechanical jack. The significance of this project is that it has culminated in the development of a new car jack design in order to make the operation easier, safer and more reliable in order to save individual internal energy and reduce health risks especially backache problems. The existing jack is modified by making small alterations and making use of an electric motor to drive the power screw. A proper gearing system has been developed to provide proper torque multiplication resulting in decreased power usage by the motor. The automobile 12V battery source operates prime mover, to facilitate easier lifting of payload. Inflator is used during side road emergency like low tyre pressure. During such situations driving cause damage to tyres, rims and may even cause accidents. Inflator consists of a motor and a compressor which works on the 12 v battery. The advantage is that this system can be used at any time. REFERENCES [1] Nitinchandra R Patel(2013); Design of toggle jack considering material selection of screw nut combination, IJIRSCT Vol.2 Issue 5, ISSN: [2] Manoj Patil(2014); Automated car jack, International journal on current environment and technology, Vol.4, No.4 All rights reserved by 384

Development of Motorized Car Jack

Development of Motorized Car Jack Ravi Kumar D Assistant Professor Mechanical Engineering SRM University Shubham Choudhary U.G. Student Mechanical Engineering SRM University Devanshu Pasbola U.G. Student