The Novel Design of Full-Balancing Mechanism for Single-Cylinder Diesel Engine Bifeng Yin 1,a, Jianguang He 2,b, Yi Xu 2,c and Yongqiang Li 2,d

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1 Applied Mechanics and Materials Online: ISSN: , Vols , pp doi:10.408/ 010 Trans Tech Publications, Switzerland The Novel Design of Full-Balancing Mechanism for Single-Cylinder Diesel Engine Bifeng Yin 1,a, Jianguang He,b, Yi Xu,c and Yongqiang Li,d 1 School of Automotive and Traffic Engineering, Jiangsu University, Zheniang 1013, P.R. China Changchai Co.Ltd, Changzhou 1300, P.R. China a ybf@us.edu.cn, b heg@changchai.com, c ccszx@16.com, d vlyq03@163.com Keywords: Diesel engine, Balancing mechanism, Reciocating inertial force Abstract. One new sliding-block balancing mechanism is oposed for the single-cylinder diesel engine. In the new mechanism, the sliding block is installed against the engine piston. The reciocation traectory of sliding block is collinear with the piston traectory, while sliding block and piston move in the opposite direction, ust like two opposite crank connecting rods. The new mechanism includes the crankshaft, connecting rod ring, the slider and the guide components. Through the bearing, connecting rod is installed in the eccentric ournal of the crankshaft. The circular connecting rod is in the accurate guiding surface of the slider; and the guide pins are in the guide groove. Guide rod connects with supporting shaft through the guide hole of the slide. The optimized parameters for the sliding block show that the ratio of eccentric distance of the eccentric ournal to the length of the connecting rod is equal to the ratio of crank radius to connecting rod length. The apoiate results can balance both the centrifugal inertia force and the reciocating inertia force generated by piston group. Even the complete balance of the first and second-order reciocating inertia forces can be obtained, which can reduce the vibration and noise of diesel engine. Introduction Engine power is ovided by the translation of reciocating linear piston motion into the crankshaft rotation. The inertia force and inertia torque generated in the movement is unfavorable to the diesel engine and complement machines, especially for single-cylinder diesel engine. Single-cylinder diesel engine is characterized in one cylinder, so it can not balance the inertia force of the crank connecting rod with the result of increasing vibration and noise. Therefore, an additional balance mechanism needs to solve the balance of crank connecting rod [1]. Presently, there are overweight balance mechanism, single axle mechanism and double axles mechanism to balance the inertia force. These mechanisms can balance rotating inertia force, however, they can only balance first-order reciocating inertia force, not second-order reciocating inertia force. The severe vibration and noise is inevitable for single-cylinder diesel engine which brings not only noise pollution but the decreasing comfort [1-]. We initialize a new sliding block balancing mechanism for single-cylinder diesel engine, which can completely balance the first and second-order reciocating inertia force of single-cylinder diesel engine. Unbalanced Forces of Single-cylinder Diesel Engine The unbalanced forces of single-cylinder diesel engine include centrifugal inertia force p r and reciocating inertia force p. p r is generated by the revolution of the unbalanced mass in the center of crankpin and p is generated by the reciocating movement of the mass in the axis. The centrifugal inertia force is balanced by the addition of a fan-shaped balance weights in reverse extension line against the crank that can oduce the opposite balanced inertia force. mrr (1) The reciocating inertia forces (p ) include first-order reciocating inertia force (p 1 ) and All rights reserved. No part of contents of this paper may be reoduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-19/0/16,3:33:0)

2 Applied Mechanics and Materials Vols second-order reciocating inertia force (p ). The common balance methods can only partly or fully balance first-order reciocating inertia force, but they can not balance the second-order reciocating inertia force [-4]. p 1 mr cos () p m R (3) cos Where R denotes crank radius (mm), φ is crank angle( A), is ratio of crank radius to length of connecting rod, m is concentrated mass of reciocating movement (kg). Full Balancing Mechanism The Structure of Full Balancing Mechanism. The new full balancing mechanism is a mechanism against piston, shown in Fig. 1. The original crankshaft is modified with eccentric ournal. The length of the eccentric ournal (e) acts as the crank radius of the balance mechanism. And the mass of the eccentric ournal is merged as part of the balance weight to reduce the fan-shaped balance weights [5]. Fig. 1 Schematic diagram for new balance mechanism Fig. and Fig. 3 show the main components and assembly relationship of the new full balancing mechanism. It includes the crankshaft, front and back bearings, front and back circular connecting rods, front and back sliders and the guide components. There are two eccentric ournals on the opposite side of the crankpin on both sides of crank. Peripheral surfaces of the circular connecting rods are composed of two concentric arcs, transitional arc. The right arc radius R1 in reverse direction of crankpin is less than left arc radius R. The distance between the R1 and R center and the axis of the crankshaft eccentric ournal denotes the working length of connecting rod ring l. Suited bearing and connecting rod ring are installed on the eccentric ournal. Guide components include guide pins which installed on top of engine body and guide peg which installed at the bottom of engine body like support shaft. Guide pins are set in the guide groove on the top of sliding block, and the guide pegs connect with the supporting shaft through the guide holes under the sliding block. Principle of Full Balance Mechanism. When the crankshaft turns, circular connecting rod which was driven by bearing on the eccentric ournal swings on the plane along outer arc surface of circular connecting rod. The sliding block which connects with circular connecting rod was driven to perform the reciocating linear motion along the centerline direction. The reciocating traectory of sliding block and the piston traectory are collinear while they move in the opposite direction, which functions as two crank connecting rods. Because the ratio of eccentric distance of the eccentric ournal to the length of the circular connecting rod is equal to the ratio of crank radius to connecting rod length, it can balance both the centrifugal inertia force and the reciocating inertia force generated by pistons group. The complete balance of first and second-order reciocating inertia forces can be obtained [5].

3 15 Advances in Engineering Design and Optimization 1-piston -connecting rods group 3-crankshaft 4-circular connecting rod 5-left sliding block 6-guide groove 7-right sliding block 8-guide hole Fig. Main components of full balance mechanism [5] 1-piston -piston pin 3-connecting rod group 4-crankshaft 5-left front sliding block 6-right front sliding block 7, 8-circular connecting rod 9, 10-ball bearing 11-left back sliding block 1-right back sliding block 13, 14-guide pin 15, 16, 17, 18-coupling bolt 19, 0-guide peg 1-supporting shaft Fig. 3 Assembly relationship of full balance mechanism [5] The Calculation of the Balance Mechanism The Substitution of Mechanism Mass. Taken a single-cylinder diesel engine as the sample, the balance mechanism was redesigned. Table 1 shows the main parameters of single-cylinder diesel engine. Three-dimensional model of balance mechanism is developed by UG software. The position of the mass center is obtained by the software, then the mass is substituted. Table shows the results.

4 Applied Mechanics and Materials Vols Table 1 Data of crank and connecting rod mechanism and sliding block mechanism Mechanism Name Magnitude Crank and connecting rod mechanism Sliding block balancing mechanism Connecting rod length (L) [mm] 185 Crank radius (R) [mm] 57.5 Connecting rod ratio ( R/ L) Eccentric length(e) [mm] 14 Circular connecting rod length ( l ) [mm] 45 Balancing connecting rod ratio ( e/ l) Table Components mass of single-cylinder diesel engine Components Mass [kg] Crankshaft (m r ) Connecting rod group (m L ) Piston group (m h ) Small end of connecting rod (m 1 ) Big end of connecting rod (m ) 1.44 Circular connecting rod (m l ) 0.97 Mass of circular connecting rod to balance reciocating inertia force (m 1 ) 0.44 Mass of circular connecting rod to balance centrifugal inertia force (m ) Rolling ball bearing (m z ) 0.6 Sliding block group (m h ) Balance Calculation of Rotating Inertia Force. Through the analysis function of UG software, we get the distance of eccentric ournal s barycenter to the axis r=6.43mm. The centrifugal inertia force of big end of connecting rod and p r in the opposite direction are as follows: mrr mr 8.8 (4) p r m r r ( m mz ) e 8.9 (5) And the balance percent of centrifugal inertia force is exessed in the following form: p r % 100% % 8.8 (6) From the results, it is clear that the new balance mechanism can completely balance the centrifugal inertia force. Balance Calculation of Reciocating Inertia Force. We get first and second-order reciocating inertia forces of piston connecting rod mechanism and sliding block balance mechanism from Eq.7- Eq.1 m mh m kg (7) m m m 9.89 kg (8) h 1 p m R (9) 1 cos cos p m R (10) cos 4.38 cos p m e (11) 1 cos cos p m e (1) cos 4.79 cos

5 154 Advances in Engineering Design and Optimization The balance ratios of first and second-order reciocating inertia forces are as follows: p 1 100% 100.9% (13) p p p 1 100% % (14) Because the reciocating inertia forces generated by crank connecting rod and sliding block mechanism are in the opposite direction, the balance ratio of the new balance mechanism reaches nearly 100%. It s concluded that first and second-order reciocating inertia forces generated by crank connecting rod mechanism can be completely balanced. Conclusions One new sliding-block balancing mechanism is oposed for the single-cylinder diesel engine. Then the centrifugal and reciocating inertia forces were calculated. The results show that the new balance mechanism can balance not only centrifugal inertia force and first-order reciocating inertia force, but also the second-order reciocating inertia force. The new balance mechanism can completely balance centrifugal inertia force and reciocating inertia force of single-cylinder diesel engine. Therefore, it can reduce vibration and noise of single-cylinder diesel engine. Acknowledgment Thanks for support from National High Technology Research Development Program of China (009AA04510). References [1] L.H. Yang: Internal Combustion Engine Design (Agricultural Machinery Technology Press, Beiing, China 1981). (in Chinese). [] K.Y. Lin, S.H. Liu and H.B. Huang: ICAFV 006. (in Chinese). [3] F.Q. Luo, Q. Wang: Transactions of CSICE, Vol. 0 (00) No. 1, pp (in Chinese). [4] Y.L. Liu, Q. Wang and F.Q. Luo: Journal of Jiangsu University (Natural Science), Vol. 3 (00) No. 1, pp (in Chinese). [5] B.F. Yin, Y. Xu and Y.K. Cheng: CN Patent, CN (009). (in Chinese).

6 Advances in Engineering Design and Optimization / The Novel Design of Full-Balancing Mechanism for Single-Cylinder Diesel Engine /