Characteristic+Simulation+of+Telescopic+Shock+Absorber.rtf

1、978-1-4244-1787-2/08/$ chmetcnvTCSC0NumberType1NegativeFalseHasSpaceTrueSourceValue25UnitNameC25.00 c Characteristic Simulation of Telescopic Shock Absorber First A. Changcheng Zhou, Second B. Yuanyi Liu, and Third C. Y

2、anhui CaiAbstract—According to the throttle slice thickness andpre-deformation of throttle slice, the velocity points of valve opening were analyzed by the relation of flux to the velocity, and the anal

3、ytic formulas of shock absorber velocity when valve opening were given. Based on this, the outer characteristic model of shock absorber was established by piecewise linear function. A practic

4、al example of simulation of shock absorber outer characteristic was given, and the performance test was conducted. The results show that the model of outer simulation is correct, the simulation values

5、 is coincide with test values, and it has important reference value for telescope shock absorber design and characteristic analysis.I. INTRODUCTIONHE shock absorber of automobile is one of the mostwith the

6、 analytic formula of throttle slice deformation, according to the velocity points at which the valve opening, the model of shock absorber outer characteristic was established by the piecewise linear function.

7、 The simulation and analysis of outer characteristic was given, and the performance test was conducted.II. ANALYSIS OF DAMPING COMPONENTSWhen the characteristic of shock absorber is analyzed, thethrottle holes,

8、piston hole and piston slot should be taken into account, meanwhile the local throttle loss must also be considered. The analysis on the structure, the throttle pressure and the flux of the throttle valves are as

9、 follows.A. Throttle Holesimportant components of suspension system, and plays a vital role in the driving process of vehicles. TheThrottle holes area is composed of a number of smallcharacteristic o

10、f shock absorber influences driving smoothness and ride comfortableness of vehicles [1]-[2]. The shock absorber used most commonly on automobile is telescopic shock absorber.The characteristic simulation h

11、as the significance for therectangular holes on slice. It could be regarded as thin-walled hole. Therefore, the relation between flux and throttle pressure can be regarded as [9]2 p 0 QA = ε A 0 (1)design of sho

12、ck absorber [3]-[4]. With the characteristic 0 ρ simulation, the flaws of design could be found and modified in time, so the design and develop could speed up, while also the test costs could be reduced. However, at

13、 present, both in Where, ε is throttle flow coefficient, which is decided bydomestic and abroad, the characteristic of shock absorber is simulated mostly with ready-made simulation software [5] - [6]. Utilizing this me

14、thod, most of necessary parameters used in the modeling of characteristic are obtained through the experiment tests, therefore, it is hard to establish the accurate simulation model, and the simulation results is a

15、lso not reliable [7]-[8]. Though some scholars had built the model of characteristic with math function, due to the inaccurate analysis of the shock absorber damping component, and the imprec

16、ise computation of throttle slice deformation and opening size of the throttle valve with the Mechanical Design Handbook which provides only thethe type of throttle holes; p 0 is the pressure of throttle holes;A

17、0is the total area of throttle holes.B. Deformation of Throttle SliceNormally, the velocity of shock absorber is quite slow, and the throttle pressure is low, thus the deformation of throttle slice could be reg

18、ard as minor deflection bending deformation. According to the calculation method of the bending deformation coefficient, the deformation [10] at valve mouth radius can be expressed asp f f = G (2)ma

19、ximum deformation proximately formula, so it is difficult to build the accuracy model.In this paper, by the analysis to the pathway throttle lossr k r k h3Where, G r is the deformation coefficient of throttle slice atcoe

20、fficient and local throttle loss coefficient of piston holes,Manuscript received July 15, 2008. This work was supported in part by the SDNSF under Grant Y2007F72 and NEDTF h is the thickness of throttle slice; pf is the

21、 pressure on throttle slice.The opening size of throttle valve is determined by the total deformation f and pre-deformation f of throttle slice atF. A. Changcheng Zhou is with Shandong University of Technology, Zibo2550

22、49, China (phone: 86-533-8333230; fax: 86-533-2786837; e-mail: greatwall@sdut.edu.cn).S. B. Yuanyi Liu is with the Shandong University of Technology, Zibo255049, China (phone: 86-533-2780023; fax: 86-533-2780023; e

23、-mail:r kvalve mouth radius, that isδ = fr k 0? f (3)Liuyuanyi@sdut.edu.cn).T. D. Yanhui Cai is with the Weihai Vocational College, Weihai 264200,China(e-mail: caiyh1965@126.com).○ 2008 IEEEr k r k r k 0207 C. Throttle

24、SlotAfter the throttle valve opening, the planar-ring throttleslot δ is generated between the throttle slice and the end ofWhere, Re is Renault coefficient. While designing the orifice, the velocity of shock absorberr kv

25、alve-seat. Therefore, the relation between the flux through throttle slot and the throttle pressure is written asπδ r 3 p fgenerally is less than the critical velocity Vc, the pathway throttle loss coefficient is calcula

26、ted according to laminar.2) Local throttle loss When oil flows through the piston hole into the cavity of the rebound valve, there are three local throttle loss, that isQ f =6 μkln( r / r ) (4)suddenly expand, reduce an

27、d direction change, respectivelyt b kWhere, μ t is oil power viscosity.D. Piston Slotthe coefficients are ζ h1 , ζ h2 and ζ h3Total local throttle loss are computed with superposition principle, and then converted i

28、nto pathway throttle loss coefficient. Therefore, the local throttle loss coefficients of rebound valve are converted into the length of piston holes,The size of piston slot δ H is determined by the fit tolerancetha

29、t is based on the piston and the cylinder inner diameter of the shock absorber. Thus, when oil flows through the pistonthat isL = ( ζ +ζ + ζ ) λ / d (9)slot, the throttle pressure is generated and can be expressed as e

30、h 1 h2 h3 h hThe equivalent length of piston hole is the sum of thepH = 12 Q μ H t H L (5)3 2 structure length and the length converted by local throttle lossπ D δ h H (1 + 1.5 e )Where, D his the cylinder inner

31、diameter;coefficient, namelyQ H is the flux L = L + L (10)that flows through the piston slot; e is the piston eccentricity rate ( 0 Vc, the flow stateof oil is turbulence, the pathway throttle loss coefficient isˉFig. 1.

32、 Oil path s before the rebound valve opening firstly.Define pre-deformation of throttle slice at valve mouthradius is fr k 0 , when the deformation is equal to thepre-deformation, the rebound valve opens first.

33、According to the formula of the slice deformation, the pressure on slice at this time is ?0.25 ª 4ShV ºλ h =0.2 Re ˙ 0.2 ?? ?? (8)??n h πd h ν ¼ p f k1 = 3h fr 0 / G r (11)208k k2008 Asia Simulation Confe