DESIGN AND MANUFACTURING CAMSHAFT USING ON HYBRID VEHICLES

Transcription

1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue, June 8, pp. 77 8, Article ID: IJMET_9 Available online at ISSN Print: 97- and ISSN Online: 97-9 IAEME Publication Scopus Indexed DESIGN AND MANUFACTURING CAMSHAFT USING ON HYBRID VEHICLES VanTuan Nguyen University Of Transport Technology, Hanoi, Vietnam ABSTRACT When working on a hybrid vehicle with the help of an electric motor, the heat engine has a working mode that is part load mode, where the engine has a high fuel consumption. One of the solutions to improve the combustion of the engine when used for hybrid car is to complete the gas distribution mechanism. When changing valve timing, engine is fuel economy, increases torque and reduce emissions. The paper presents the basis of calculation, design; fabrication and inspection of the camshaft processes in accordance with the parameters have been determined to ensure the use. Camshaft is calculated and designed by AVL - Excite software using Polydyne method. Then, the improved camshaft is machined according to the selected process, meeting the set technology requirements. The basic parameters of the improved camshaft are checked on the meter, the tolerances are within the allowed value (the error of the working angle is from. to %). This confirms the accuracy of the processing method compared to the design. Keywords: Camshaft, design, manufacture, gasoline engine, hybrid vehicles. Cite this Article: VanTuan Nguyen, Design and Manufacturing Camshaft Using on Hybrid Vehicles, International Journal of Mechanical Engineering and Technology, 9(), 8, pp INTRODUCTION The gasoline-electric hybrid car is the vehicle of interest to researchers, manufacturers and consumers to save fuel and reduce environmental pollution []. With hybrid cars, the heat engine is the main source of supplying energy for the car's operation, thanks to the electric motor that the hybrid engine in the hybrid car has the work mode that is the part load. In this mode, the engine consumes a lot of fuel []. Therefore, it is necessary to improve the working efficiency of the heat engine so that the combustion process is better, thereby reducing the fuel consumption. One of the ways to improve the efficiency of a heat engine is to design and manufacture a camshaft with a new valve timing [] editor@iaeme.com

2 Design and Manufacturing Camshaft Using on Hybrid Vehicles Today, for crystal processingcircular surfaces in machine-building, conventional machining methods such as grinding and lathe are used. For non-circular shaped surfaces that are often used for grinding, splicing, milling on the center CNC milling... In fact, in mass production, block welds are often used for engraver sharpening and milling, the electric-spark machining is used only for complex and requiring precision surfaces because of the high cost and taking a lot of time [,]. Sharpening is fine machining the detail pattern on specialized grinders. Engraver sharpening has the advantage of high productivity and quality [,7]. However, the disadvantage is that the accuracy and quality of the surface of the part depend very much on the precision of the part used to make the specimen during machining, the precision of the grinder and the quality. of grindstone. Another solution for fine machining non-rotating shaped surfaces, without the need for specimen in the machining process, is the hollow milling method on the CNC milling center. For internal combustion engines, the camshaft is a very important part for the engine to be clean and refilled, if the valve timing is wrong, engine will not work or the engine consumes a lot of fuel, The amount of toxic substances in the exhaust gas will increases. For the highprecision camshaft, the camshaft design must be carried out carefully according to the calculation and the machining process is reasonable. Currently, high-speed motors are often used with camshaft with profiles that are designed according to the given motion rules of xupap. When the initial cam settings are chosen correctly, this type of profile ensures that the camshaft closes and opens smoothly and does not cause the impact of the gas distribution mechanism, which is called the cam profile design with not impact method. With the heat engine applied to hybrid vehicles the working area of the engine has been narrowed, so the design and optimization of the cam profile can be done by various methods. However, in this paper the author uses AVL - Excite software to calculate and design a non - collision camshaft profile with the Polydyne method, thereby designing the camshaft and machining the camshaft on CNC milling machines with chopping-knife cover PVD, CVD or CPN.. CALCULATION OF CAM PROFILE.. Model of camshaft calculation a) b) Figure The gas distribution structure model in I SOHC engine with AVL Excite a). Scheme of overhead camshaft system drives valve through the lever b). Alternative equivalent model ISOHC engine air distribution system with overhead camshaft, the torque is transmitted from the crankshaft to the chain and drives the camshaft; the camshaft act fingers to push and the open valve, valve spring close the valve. The regular operation region of the city-cycle 78 editor@iaeme.com

3 VanTuan Nguyen heat engine is rpm rpm. This speed range is much narrower than the original speed range when the motor alone n = rpm rpm. With the narrow speed range, the adjustment of work cycle will be highly effective. In this area we calculate the valve timing for point n = rpm; M = 8.7 N.m, early opening angle of intake valve φ = (crankshaft angle), angle of late intake valve φ = 9 (crankshaft angle); early opening angle of exhaust valve φ = (crankshaft angle), angle of late exhaust valve φ = (crankshaft angle). The author develops the valve timing model using AVL Excite software as shown in Figure... Design of camshaft When calculating the optimum cam profile, the initial calculation condition is as follows: Inlet camshaft profile and exhaust camshaft profile: The cam profile in polar coordinates has been calculated using the AVL Excite software in the optimal way. Dimensions of the original camshaft: Axle diameter, axle, cam spacing, keyhole, oil- hole, remain the original camshaft. Deflection angle of the top points of each cam: is the important parameter and decide the accuracy of the selected valve timing. In order to determine the angle of deflection of the camshaft, for the original engine, this is based on the pulley positioning pin as the standard for the exhaust camshaft of the first cylinder as standard alignment with the locating pin. And the system should be adjusted between the time of opening and closing valve with the position of the piston. When calculating the redesign of the camshaft profile, valve timing changes, thus it is important not to break the synchronization of the system... Evaluating the results of cam design with Polydyne method From the results of calculating the lifting stroke of the intake valve, after synthesizing, we get to evaluate the kinematic parameters and dynamics of the gas distribution structure with optimal cam profile. Let j +, j- is the positive acceleration and negative acceleration has the greatest absolute value of valve. Through the results of the kinematic and dynamic calculation of the gas distribution structure of the optimization scheme, the author has some comments as follows: According to Figure, Figure, although the maximum displacement of the valve for the optimal scheme is not greater than the original, but due to the lateral angle of the load it increases, the time value of the cross sectional area of the optimal project is greater than primitive Cam Follower Lift (mm) Cam Follower Lift Mod (mm) Cam Follower Velocity (mm/rad) Cam Follower Velocity Mod (mm/rad) Cam Follower Acceleration (mm/rad^) Cam Follower Acceleration Mod(mm/rad^) Acceleration (mm/rad^) Velocity (mm/rad) Lift[mm] Figure Results of the original camshaft and new intake cam 79 editor@iaeme.com

4 Design and Manufacturing Camshaft Using on Hybrid Vehicles Cam Follower Lift (mm) Cam Follower Lift Mod (mm) Cam Follower Velocity (mm/rad) Cam Follower Velocity Mod (mm/rad) Cam Follower Acceleration (mm/rad^) Cam Follower Acceleration Mod(mm/rad^) - -9 Acceleration (mm/rad^) Velocity (mm/rad) Lift[mm] Figure Results of the original camshaft and new exhaust cam The inlet camshaft contact pressure of 7 MN/m of the optimum is within the allowable range. The speed of the finger tail at the transition area is within the allowable range and smaller than the original cam. The velocity at the transitional area of the fingers, intake valve and exhaust valve is not change much to allow the gas distribution mechanism to work smoothly. Positive acceleration and negative acceleration are within acceptable limits, however the absolute value of the maximum positive acceleration is greater than that of the original cam, since the increasedcross sectional value can increase the level of circulation. The speed of opening valve must be fast enough to maintain the highest position for a long time and close quickly. The results of the new camshaft profile after design are shown in Figure, Figure. Lift[mm] Valve Lift (mm) 8 Valve Lift Mod (mm) Lift[mm] 8 7 Valve Lift (mm) Valve Lift Mod (mm) 8 Figure The intake valve lifting of original cam and new cam Figure The exhaust valve lifting of original cam and new cam The cam with the profile as shown in Figure, Figure 7 after the design will be machined on the CNC machine. The camshaft after the design is shown in Figure 8. R (mm) R (mm) Figure New intake cam profile Figure 7 New exhaust cam profile 8 editor@iaeme.com

5 VanTuan Nguyen , T Xylinder Xylinder Xylinder 9 T Cam Ex_ 7 9,,,,,, T Cam In_, T Figure 8 The new camshaft. ESTABLISHMENT OF TECHNOLOGICAL PROCESS AND MACHINING OF CAMSHAFT.. Workpiece The camshaft is made of XC alloy steel workpiece with a hardness of -HRC. When machining to have a detail as required, we need to cut off layers of metal, so it is necessary to draw detailed drawings of workpiece. The shape of the embryo is completed on the basis of the caculating residual and tolerances as shown in Figure 9. Ø Ø 9 7 Figure 9 The workpiece design of the new camshaft.. Processing of camshaft on CNC machine Figure CNC Machining Center After calculating the design of the camshaft of theconversion engine with the basic software AVL Boost and AVL Excitte, the author carries out processing the camshaft at the CNC center, this is a new technology and is being applied in precision machining. Nowadays, fine machining of circular surfaces in machine-building is done using common machining methods such as grinding and turning. In thehollow milling operation at the CNC milling center shown in Figure and Table, use the AlTiN coated end mill with X alloy steel (contour) with the proper cut modes. 8 editor@iaeme.com

6 Design and Manufacturing Camshaft Using on Hybrid Vehicles Table Specifications of the machine Parameters Size Unit Work area size x mm Travelling capacity X axis 8 mm Travelling capacity Y axis mm Travelling capacity Z axis mm Main spindle diameter Φ mm Cutting speed (Feed rate ) mm/min Fast feed X-Y axis mm/min Fast feed Z axis mm/min Main engine power.7. kw Secvo engine X, Y, Z.. kw Weight kg Spindle speed 8 rpm Tool BT Overall dimensions x x mm After evaluating equipment and technology of camshaft are being used, the authors choose the solution of camshaft processing on CNC machine with process technology is shown in Table. Table Camshaft machining technological process Manufacturing step Content Specifications Step Preparing the workpiece Use XC steel Step Face turning, processing centre hole and profile turning in turn camshaft and cam Standard surface machining in one attachment Step Milling the camshaft on a DMU - Milling in turn from rough, semi-fine axis milling machine to fine Step Machining the camshaft pillow Using lathe center and chuck Step Slot milling take power distributor at the shaft end After machining the camshaft shape is shown in Figure. Figure The camshaft after machining Check the camshaft conversion after process. The camshaft after fabrication was carried out to check the technical parameters during and after the process. The basic parameters to be checked include: The size of the axes. The concentricity of the axes Cams and eccentric wheels. For cams, in addition to checking the cam profile size, they have to check their distribution angles. Figure shows the principle of examining the shape and distribution of cams. If the cam has any error in shape and angle of distribution, the "H" check height will change and be indicated on the meter. There are also parts that calculating respective rotational angles of the shafts on the device. 8 editor@iaeme.com

7 VanTuan Nguyen After measuring the camshaft, processing the results and comparing with the design, the results show that the camshaft shape parameters are within the allowable limits, The surface hardness and gloss of the machined surfaces reaches the technological norm. Since then, the improved camshaft has been made to meet the working conditions and when installing the camshaft on the ISOHC engine to run the test later. The results of the improved camshaft working angle inspection are shown in Table. Figure Checking the cam profile. Testing camshaft,. Sample camshaft,. Check clock Table The improved camshaft working angle inspection results Camshaft Design Cam angle [deg] Measurement Cam angle [deg] Error Cam angle [deg] Intake,',' ' Exhaust,' 7' After checking the test parameters are within the allowable limits, the index of surface hardness and gloss of machined surfaces reach the technological norm. From there, the improved camshaft was built to meet the working conditions, followed by the installation of camshaft on I SOHC engines for testing.. CONCLUSION Research shows that with the AVL-EXCITE software, the process of calculating the design of the gas distribution system can be made easily and quickly, resulting in high efficiency, shortening the test time in the fabrication. The improved camshaft processing technology with non-impact profile has been selected as the complex profile and optimal valve timing has been selected based on the equipment and technology available in the country.. The use of PVD TiAlN coated end mill to cut steel with high hardness (> HRC) with high performance and good quality of surface (Ra =.) helps to make improved camshaft according to the selected process, improved camshaft meets the technology requirements. After checking the test parameters are within the allowable limits, the index of surface hardness and gloss of machined surfaces reach the technological norm. The error of the biggest geometric parameter in the working angles of the cams is 7'camshaft rotation angle. 8 editor@iaeme.com

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