Innovative Design of an Automatic Car-Door Opening System

Transcription

1 Innovative Desin of an Automatic Car-Door Openin System Hsin-Shen Lee and Lon-Chan Hsieh Abstract To improve the existin mechanism for openin the car-door of a mobile shop vehicle, we first apply the contradiction matrix and the idealized desin technique of the Theory of the Solution of Inventive Problems (TRIZ) as a reference to ameliorate an automatic car-door openin (closin) system, and find a scheme matchin requirements in desin. Next, a motor transmission system is desined based on analyses & desin theory for motion of a train. Finally, an automatic car-door openin (closin) system with desin in enineerin is devised under constraints in desin for automatic openin (closin) of a car door. With the systematic scheme for innovative automatic car-door openin (closin) desin evolved to a prototype in this study, the research can be taken as a model for development of an automatic car-door openin (closin) system in the industry. Index Terms Automatic car-door openin (closin) system, TRIZ Theory I. INTRODUCTION As a result of lower costs for enterprise pioneerin and flexible maneuverability, the mobile shop vehicle has been fashionable in recent years. The purpose of this paper is to improve openin mechanism, cut down the cost, and increase the practicability in the industry of a mobile shop vehicle. First, we analyze the structure and car-door openin method of mobile shop vehicle to find any drawback. Then, the desin of amelioratin openin of the car-door is conducted. Due to an innovative idea transferred to systematic information, this automatic car-door openin system can be rearded as a model for desinin this system with various features such as simple secure structure, lon life expectancy, and easily-adjusted & effort-savin openin motions. tarpaulin []-[] is analyzed and contrasted in this study to summarize relevant requirements, restricted conditions and specifications in desin. Divided to both operation mechanisms, human operation and auxiliary-tool operation, for the structure of the car frame and tarpaulin, the former []-[5] has complicated structure causin laborious and time-consumin drawbacks and the latter [6]-[] has defects such as hih maintenance and manufacturin costs, short life expectancy, and heavy weiht. Amon some patents with respect to the above descriptions, T. S. Chun [], who used hydraulic cylinder to drive a car frame, improved the win-type car door structure with advantaes of shelterin rainfall and sunshine, larer space due to openin at three lateral sides, and innovative style but shortcomins of complicated openin structure with a hydraulic drive system, hih costs, and heavy weiht. The ameliorated win-type car door structure is shown in Fi.. Still, the ameliorated win-type car door structure [] is selected as an oriinal mechanism in our study expectin to lower costs and increase facilitation in operations in this car-door openin system. II. LITERATURE REVIEW As a reference of desinin an automatic car-door openin (closin) system, the existin car frame and Fi.. The ameliorated win-type car door structure [] Manuscript received January 08, This work was supported by the National Science of the Republic of China and One-i Company of Taiwan under NSC E CC3. Hsin-Shen Lee was born in 957. She is an associate professor of Power Mechanical Enineerin of National Formosa University in Taiwan. Her research specialties include creative enineerin desin and computer-aided desin ( jennifer@nfu.edu.tw) Lon-Chan Hsieh was born on March, 958. He received his B.S., M.S., and Ph. D. from Mechanical Enineerin of National Chen Kun University in 980, 988, and 993, respectively. Dr. Hsieh had worked in Industry Technoloy Research Institute since 983 to 988. Now, he is a professor of Power Mechanical Enineerin of National Formosa University in TAIWAN. His research specialties include mechanism desin, orthosis desin, and Transmission system desin (correspondin author. tel: ; fax: ; lochsieh@nfu.edu.tw). III. APPLICATIONS OF TRIZ THEORY TRIZ, a Russian acronym of Teoriya Resheniya Izobretatelskikh Zadatch which means Theory of the Solution of Inventive Problems, is developed by a Russian enineer Genrich Altshuller. After readin more than 200 thousand patents, Mr. Altshuller and his colleaues concluded the innovation or invention for an enineerin system is not a random event because a person s capability for invention and creation is trainable. In liht of aruments of the TRIZ theory, the eneral evolution theory available to the technical system can be developed into methods or tools

2 to solve oriinality [2]-[3]. A. Contradiction Matrix Analyzin more than 200 thousand patents since 950 s, Genrich Altshuller and his colleaues developed the contradiction matrix as one tool to solve contradictions in techniques by inducin 39 enineerin parameters and 40 creation principles. Based on the TRIZ theory, the existin systems always contain contradictions and an innovation is materialized with these contradictions excluded from a question. To find a feasible solution principle, Genrich Altshuller arraned 39 enineerin parameters into two axes of the matrix wherein the vertical axis contains parameters to be improved and the horizontal axis includes parameters avoidin to be deteriorated. The correspondin rid intersected by both contradiction parameters is the solution principle recommended. Because the costs for the car-door openin system and the facilitation for operatin the oriinal mechanism [] are expected to be lowered and increased, respectively, parameters to be improved are fixed members areas (6), power (2) and device complexity (), and parameters avoided to be deteriorated are fixed members lenths (4), strenth (4) and reliability (27). As shown in Table for the contradiction matrix, the most frequent solution principle is Principle 26, simplified and inexpensive objects employed to replace hih-priced ones. For the sake of reducin costs, the manner of openin the car frame is chaned to a mechanism driven by motors and connectin rods. As shown in Fi. 2, the scheme for automatically openin a car frame is: The Motor (5) links the Linkae (4), which connects the Car Door () with the Linkae joints(3), and the Lateral Car Door (2) forms an anle of 90 derees with the Car Door (). Activation of the Motor (5) is able to drive the Connectin Rod Assembly (4) which drives the Car Door () to open the Lateral Car Door (2). Table The contradiction matrix Improvin Factor 6 Worsenin Factor Area of stationary object 2 Power Device complexity 4 Lenth of stationary object 26,27 9, Strenth 40 26,0 28 2, Reliability 32,35 40, 4 9, 24 26,3 3,35 Fi.2. The scheme of automatic openin car door B. Idealized Desin Theory The concept of idealized desin developed by Genrich Altshuller emphasizes that any technical system is always evolved to a simplified, effective, idealized system within its life cycle. Supplyin a systematic method to help a desiner to correctively define questions, the idealized desin theory can enerate innovative concepts for idealized tarets. Due to six steps for definin and analyzin questions to discover a scheme for settlement in an idealized desin, the steps for an idealized desin in this study are: ) Finalized tarets for one desin: Improvement for openin a car frame, reduction in costs, and increase in practicability for the industry. 2) Idealized solution: Development of a controllable sinle-side car-door openin (closin) system to realize liht weiht, lower costs, and no rock of the body with the car frame opened. 3) Obstacles for idealized solutions: Owin to complexity of the hydraulic openin system, the hydraulic cylinder, hydraulic pumps, and pipelines need to be reularly maintained or oil leakae is inevitable. The hydraulic equipment is required to match a vehicle s dimensions and has hih costs and weiht. Lackin a self-lockin function, the car doors without an extra safety device added may cause daner while radually slippin downward. 4) Results with obstacles occurred: Employment of a hydraulic openin system. 5) Conditions without obstacles occurred: Another openin system to replace the hydraulic openin system. 6) Usable resources for creation of these conditions: Car frame, car doors, motors, and lead screws. The scheme for idealized solutions based on employment of a displacement system and chanes in operation principles: ) Displacement system: Displace the hydraulic drive openin system in the oriinal mechanism with the motor- and -driven openin system. 2) Chanes in operation principles: To improve drawbacks in the openin system of the innovative desin scheme (Fi. 2) such as members easily eroded, contaminated and occupyin lare volume as a result of exposure outside a car body and to materialize reduction in costs and simplification of openin operations, the position for the openin system in this desin scheme is chaned with motors, worms and s placed on the car frame as well as the linkae chaned to an electric motor- cylinder, which is driven to open the car door by activation of motor, worm and worm. IV. DESIGN OF THE INNOVATIVE SCHEME A. The Desin of Automatically Car-Door Openin System The objective of this study is to explore major specifications and functions of an automatic car-door openin system and propose new desin concepts as references of desinin this system. The automatic car-door openin system includes electric motor- cylinders and

3 car-door mechanisms. The purpose of this paper is to reduce the volume of automatic car-door openin system and increasin facilitation in operations. The electric motor- cylinder is composed of motor, worm and worm reducer, and screw pair. The desin [4]-[5] for the automatic car-door openin system is described as follows:. Electric motor- cylinder () The desin of worm and worm reducer Based on features of the trains, we desin the worm and worm reducer matchin the requirements in speeds of the automatic car-door openin system. Fi. 3 shows the electric motor- cylinder includin DC motor, worm and worm reducer, and screw pair. The worm (Nw = ) is the input terminal adjacent to DC motor, and the worm (N = ) is the output terminal adjacent to a sinle-thread screw. Hence, the ratio reaches a hih value of for control of rotatin speeds of a worm. Fi.4. Cross-section view of box The motion equation for the screw and slider is: V = ω (3) slider L screw screw With lead of screw L screw = 4 mm and rotatin speed of worm (= rotatin speed of screw) ω = ω = rpm, substituted into Equation (3), we et: screw 00 V slider = 4mm 00( rpm) = 6.667( mm / sec) 60 ( rps / sec) (4) Fi.3. Electric motor- cylinder The motion equation for the worm and worm system [6] is: ω N worm r = = () ω N With motor s input rotatin speed (= rotatin speed of worm) ω worm = 00 rpm, worm N w =, and worm N =, substituted into Equation (), we et: r 00rpm = = ω w Accordin to equation (2), the rotatin speed of a worm at the output terminal is ω = 00 rpm = ω. screw (2) The desin of screw and slider (nut) Screw pair is composed of screw and slider. The rotatin motion of screw can be chaned to the linear motion of slider (nut). It matches the kinematic requirements of automatic car-door openin system. Fi. 4 is the cross-section view of box. (2) Thus, the velocity of slider is 6.667mm/sec and that is the liftin velocity. Based on the above results, the major specifications and functions of electric motor- cylinder are shown in Table 2. Table 2 The specifications for electric motor- cylinder Motor 24V, 70W Motor s input rotatin speed (= rotatin speed of worm) 00 rpm Teeth number of worm T Teeth number of worm T Gear ratio of worm and worm pair rotatin speed of worm (= rotatin speed of screw) 00 rpm Screw lead 4 mm Linear speed of slider (nut) (Liftin speed) 6.67 mm/s 2. The desin of car-door openin mechanism After the desin of motor- transmission system, the next work is to desin the car-door mechanism. The requirements and specifications of the automatic car-door openin system are described below:

4 ) The car-door system must have automatic openin functions. 2) Adopt the electric motor- cylinders as the power devices of automatic car-door openin system for hiher reliability. 3) Add an electric controller to simultaneously control two electric motor- cylinders to open each side car-door by user. 4) The rotatin speed of DC motor is 00rpm and the ratio of worm and worm reducer is, hence the rotatin speed of output shaft (worm ) is 00rpm. 5) The lift of the slider is 250mm. 6) The lead of crew is 4mm. B. Enineerin Desin In this study, the scheme for desin of the automatic car-door openin system coverin the electric motor- cylinders and the car-door openin mechanisms. The enineerin desin contains strenth desin, structure desin, and enineerin drawin. Fi.7 shows the appearance of electric motor- cylinder with total stroke 250mm. The automatic car-door openin system has four roups of electric motor- cylinders equipped between car door and car frame. As shown in Fi. 8, the automatic car-door openin system has two electric controllers overnin the motion of car-door openin mechanism. Accordin to the desin constraints of automatic car-door openin system, the automatic car-door openin mechanism can be desined by 4-bar linkae (RRPR) which is the inversion of slider-crank. Fi. 5 shows the structure skeleton of the RRPR 4-bar linkae. Link 3 and link 4 forms a prismatic pair and can be substituted by motor- transmission system shown in Fi.3. Fi.7. Electric motor- cylinder Fi.5. Car-door openin mechanism (RRPR 4-bar linkae) With the sinle-side hand-controlled device pressed, the activated motor will drive the electric motor- cylinders to work and finally open the car-door because of electric motor- cylinders installed between the car-door and the car-frame. The rotatin directions of all members in the car-door openin system are shown in Fi. 6. (a) car-door openin (b) car-door closin Fi.8. The automatic car-door openin system Fi.6. The rotatin directions of the car-door openin system V. CONCLUSIONS Achievements derived from this study: ) Supply of an innovative process and method for an automatic car-door openin (closin) system as references of systematic desin of this mechanism.

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