Novel Micro Free-Piston Swing Engine and Its Feasibility Validation - ZHANG Shimin.pdf

7/27/2019 Novel Micro Free-Piston Swing Engine and Its Feasibility Validation - ZHANG Shimin.pdf

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TSINGHUA SCIENCE AND TECHNOLOGYI S S N 1 0 0 7 - 0 2 1 4 17/21 p p 3 8 1 - 3 8 6V o l u m e 10, N u m b e r 3, J u n e 2 0 0 5

Novel Micro Free-Piston Swing Engine and ItsFeasibility Validation

ZHANG Shimin (5M &),WA NG Jinsong GUO Zhip ing ( # 4 ^ )Inst i tute of M an u f ac t u r i n g E n g i n eer i n g , D ep ar t m en t of Preci s ion Ins truments and M e c h a n o l o g y ,

Ts inghua Univers i ty , Bei j ing 100084, China

Abstract: To d e v e l o p h i g h e n e r g y - d e n s i t y m i c r o p o w e r g e n e r a t i o n s y s t e m s , a n o v e l t w o - s t r o k e c y c l e m i c r of r e e - p i s t o n s w i n g e n g i n e ( M F P S E ) , i n s p i r e d by the c o n c e p t of the m i c r o i n te r n a l c o m b u s t i o n s w i n g e n g i n e ,i s p r o p o s e d to s u p p l y m e c h a n i c a l p o w e r for a m i c r o p o w e r g e n e r a t i o n s y s t e m . The w o r k i n g p r i n c i p l e , gase x c h a n g e an d i g n i t i o n t i m i n g c o n t r o l c y c l e s , an d s t r u c t u r e and o p e r a t i o n a d v a n t a g e s of the M F P S E ar e d i s c u s s e d in d e t a i l . A p r o t o t y p e w h e r e the t i m i n g c o n t r o l and g e o m e t r i c p a r a m e t e r s ar e d e s i g n e d w i t h r e f e r e n c e to a t r a d i t io n a l t w o - s t r o k e c y c l e i n t e rn a l c o m b u s t i o n e n g i n e is f a b r i c a t e d . The s u c c e s s f u l i g n i t i o n ex-p e r i m e n t s h o w s t h a t t h i s new c o n c e p t e n g i n e is f e a s i b l e and is w o r t h y of f u r t h e r s t u d y .

Key words: t w o - s t r o k e c y c l e ; f r e e - p i s t o n e n g i n e ; s w i n g o u t p u t

IntroductionA s a r esu l t of t h e c o n t i n u o u s and r a p i d d e v e l o p m e n t ofp o r t a b l e e l e c t r o n i c d e v i c e s , h i g h e n e r g y - d e n s i t y p o w e rs o u r c e s are u r g e n t l y r e q u i r e d . H o w e v e r , the e n e r g y -d en s i ty of ch emica l s to r ag e ce l l s w id e ly u sed by p o r t ab le e lec t ro n ic d ev ices has o n l y i n c r e a s e d by a f ac to ro f two o v er the l a s t d ecad es ; far l e s s th an the i n c r e a s e dd e m a n d for h ig h er d en s i ty p o wer so u rces o v er thes a m e p e r i o d .

A s an a l te rn a t iv e to i m p r o v i n g the e n e r g y - d e n s i t y ofch emica l s to r ag e ce l l s , s c ien t i s t s h av e a l so s ta r ted inr e c e n t y e a r s to d e v e l o p new p o w e r s o u r c e s [ 1 _ 5 ] . In t h e s eef fo r t s , o win g to the v ery h ig h en erg y d en s i t ies ofl iq u id or g aseo u s fu e ls and the h i g h e n e r g y c o n v e r s i o nef f ic ien cy of i n t e r n a l c o m b u s t i o n p r o c e s s e s , it s e e m sth a t th e re is m o s t p o t e n t i a l in e m p l o y i n g the r e la t iv e lyc o m p l e x i n t e r n a l c o m b u s t i o n s y s t e m s for p o w e r

R ece i v ed : 2 0 0 4 -0 3 -0 1* S u p p o r t ed by the N at i o n a l N a t u r a l S c i en ce F o u n d a t i o n of C h i n a

( N o . 5 0 3 7 5 0 7 8 )* * To w h o m co r r e s p o n d en ce s h o u l d be ad d re s s ed .E -m a i l : w an g j s @ t s i n g h u a . ed u . cn ; T e l : 8 6 -1 0 -6 2 7 9 7 0 3 9

g e n e r a t i o n s y s t e m s . H o w e v e r , at p r e s e n t , the a p p r o a c his la rg e ly fo cu sed on s c a l i n g d o w n the ex is t in gm a c r o s c a l e p o w e r g e n e r a t i o n s y s t e m s i n t o m i c r o s c a l ev e r s i o n s , w i t h the h o p e of u s i n g m o r e a d v a n c e dm a n u f a c t u r i n g t e c h n i q u e s , s u c h as m i c r o e l e c t r o m e c h a n i c a l s y s t e m s ( M E M S ) , to a c h i e v e thep r o d u c t i o n r e q u i r e m e n t s . In f ac t , th ese p ar t icu la rc o m b u s t i o n s y s t e m s do not a p p e a r to be e s p e c i a l l yw e l l - s u i t e d for m i n i a t u r i z e d o p e r a t i o n , b e c a u s e m o s t oft h e i r m a j o r c o m p o n e n t s m u s t be r e t a i n e d at ther ed u ced sca le in o r d e r for the s y s t e m to fu n c t io np r o p e r l y . It is ap p aren t th a t the id ea l in te rn a lco mb u s t io n sy s tem sp ec i f ica l ly in ten d ed for o p e r a t i o nat the m i c r o - s c a l e l e v e l is l ik e ly to be v ery d i f f e r en tf ro m th a t ru n n in g b es t at the m a c r o - s c a l e l e v e l .M o r e o v e r , as a c o n s e q u e n c e of th e l imi ted av a i lab i l i tyo f f e a s i b l e m a n u f a c t u r i n g p r o c e s s e s , the s c a l e - d o w na p p r o a c h r e q u i r e s m o s t of t h e t i m e and the effort to bes p e n t on how to b u i l d the s c a l e - d o w n c o m p o n e n t sb efo re a p o i n t can be r e a c h e d w h e r e the s y s t e m can bes t u d i e d as a w h o l e .

T o o v e r c o m e the p r o b l e m s met in the effor ts ofm i n i a t u r i z i n g l a r g e s c a l e p o w e r g e n e r a t i o n s y s t e m s ,D a h m et al. h a v e d e v e l o p e d a new c o n c e p t m i c r o


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3 8 2 Tsinghua Science and Technology, June 200 5, 10(3) : 381 - 3 86

i n t e r n a l c o m b u s t i o n s w i n g e n g i n e ( M I C S E ) [ 6 ] , wh ich i sc o m p o s e d o f f o u r c o m b u s t i o n c h a m b e r s i n o n e b a s ep la te , wh ere each o p era t in g cy c le in c lu d es fo u r s t ro k es .Th e M IC SE is th e fi r st en g in e esp ec ia l ly d es ig n ed fo rm a n - p o r t a b l e p o w e r g e n e r a t i o n s y s t e m s . I t a l s orep rese n ts a b r ea k th ro u g h fo r r ea l iza t io n o f man -p o r t a b l e p o w e r g e n e r a t i o n s y s t e m s .

In sp i r ed b y MIC SE sy s tem, an d in o rd er to fu r th ers imp l i fy th e s t ru c tu re an d th e co n t ro l sy s tem o f th i sty p e o f in te rn a l co mb u s t io n en g in e , a n ew m icro f r ee -p i s t o n s w i n g e n g i n e ( M F P S E ) h a s b e e n d e v e l o p e d a tT s i n g h u a U n i v e r s i t y [ 7 ] .1 M FP SE Structure Description and

Working Principle1 .1 Stru cture desc r ipt ionI n c o n t r a s t t o t h e M I C S E , t h e M F P S E i s a t w o - s t r o k ec y c l e m i c r o i n t e r n a l c o m b u s t i o n s w i n g e n g i n e , w h e r eth e mech an ica l p o wer i s a l so o u tp u t b y mean s o f aswi n g in s tead o f b y ro ta t io n as in t r ad i t io n a l in te rn a lc o m b u s t i o n e n g i n e s . A s c h e m a t i c d i a g r a m o f t h e s t r u c tu re o f th e MFPSE is i l lu s t r a ted in F ig . l .

Exhaus t por tC o m b u s t i o nch am b er A

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R eed v a l v e

C o m b u s t i o nch am b er

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P re - co m p r es s i o nch am b er

In le t por tBody

Transfer por t A S wing arm Transfer por t Fig. 1 Schem at ic diagram of the MF PS E

A swin g a rm i s in s ta l led in th e cen te r o f th e cav i ty ina s in g le b ase s t ru c tu re , d iv id in g th e cav i ty in to fo u rc h a m b e r s . T h e u p p e r t w o c h a m b e r s , l a b e l e dc o m b u s t i o n c h a m b e r A a n d c o m b u s t i o n c h a m b e r B ,s e r v e a s c o m b u s t i o n c h a m b e r s ; t h e l o w e r t w oc h a m b e r s , l a b e l e d p r e - c o m p r e s s i o n c h a m b e r A a n dp r e - c o m p r e s s i o n c h a m b e r B , s e r v e a s p r e - c o m p r e s s i n gfor the f resh charge. The swing arm is also used as as e a l i n g p a r t b e t w e e n t h e c h a m b e r s . T h e r e a r e t w ot r an s fe r p o r t s o n th e h in g e su r f ace o f th e swin g a rm,sy mmetr ica l ly lo ca ted w i th r esp ec t to th e lo n g ax is o fthe sw ing arm . A n outpu t shaf t is f ixed in the cent er of

th e swin g a rm b y a b o n d . In each p re - c o m p res s io nch amb er , th e re i s a r eed v a lv e co v er in g th e in le t p o r t tose rv e as a ch ec k v a lv e fo r th e p re -m ix ed a i r / fu e lmix tu re . Th e ex h au s t p o r t i s a t th e b isec to r o f th e u p p ert w o c o m b u s t i o n c h a m b e r s , a n d s h a r e d b y t w oc o m b u s t i o n c h a m b e r s . A l o n g t h e a x i s o f t h e o u t p u tshaf t , a f ront cover and a back cover are f ixed on theb ase s t ru c tu re . A l l th e ax ia l an d r ad ia l c lea r an cesb e tween th e swin g a rm an d th e b ase s t ru c tu re a r e15 .

I t i s ap p aren t th a t th e MFPSE is a two -cy l in d ersu p er - ch arg ed micro in te rn a l co mb u s t io n en g in e . I t canb e e n v i s a g e d a s t w o c r a n k c a s e - s c a v e n g e d i n t e rn a lco m b u s t io n en g in e s in p ara l le l d es ig n e d o n o n e b ases t ru c tu re .1 .2 W o r k i n g p r i n c i p l eTh e wo rk in g p ro cess an d th e f lo w d i r ec t io n s a r e i l lu s t r a ted in F ig . 2 . Su p p o se th a t co mb u s t io n ch amb er A i sa t t h e p o s i t i o n o f t h e t o p d e a d c e n t e r ( T D C ) t h e v e r yb e g i n n i n g o f t h e c o m b u s t i o n / e x p a n s i o n p r o c e s s . T r a n s f e r p o r t A an d ex h au s t p o r t a r e th u s c lo sed b y th eswin g a rm ( F ig . 2 a ) ; th e co mp resse d mix tu re i s ig n i tedb y a sp ark p lu g , an d th e swin g a rm wi l l b e p u sh ed to w a r d s t h e b o t t o m d e a d c e n t e r ( B D C ) o f c o m b u s t i o nc h a m b e r A . I n t h e m e a n t i m e , c o m b u s t i o n c h a m b e r i s a t t h e po s i ti o n o f i ts o w n B D C t h e v e r y b e g i n n i n go f t h e c o m p r e s s i o n p r o c e s s . T r a n s fe r p o r t a n d e x h au s t p o r t a r e b o th o p en ed , th e scav en g in g p ro cesstak es p lace , an d th e f r esh ch arg e sweep s th e b u rn t g as -ses o u t f ro m i t . Wh en p re -co mp ress io n ch amb er A i s a tt h e b e g i n n i n g o f t h e p r e - c o m p r e s s i o n p r o c e s s , t h e r e e dv a lv e w i l l b e c lo sed a t o n ce ; th e p ressu re o f th e mix tu re in s id e w i l l in c rease as th e swin g a rm mo v esc l o c k w i s e . W h e n p r e - c o m p r e s s i o n c h a m b e r i s a t t h eb eg in n in g o f th e p re - in tak e p ro cess , th e r eed v a lv e w i l lb e o p en ed b y th e v acu u m fo rmed in i t a s th e swin g a rmm o v e s c l o c k w i s e .

W h e n t h e s w i n g a r m s w i n g s c l o c k w i s e t o t h e T D Co f c o m b u s t i o n c h a m b e r B , c o m b u s t i on c h a m b e r w i l lb eg in i t s co mb u s t io n /ex p an s io n p ro cess , ex ac t ly as fo rc o m b u s t i o n c h a m b e r A ( F i g . 2 c ) . H o w e v e r , t h i s t i m et h e h i g h p r e s s u r e p r o d u c e d i n c o m b u s t i o n c h a m b e r w i l l p u s h t h e s w i n g a r m s w i n g i n g c o u n t e r c l o c k w i s e . I no t h e r w o r d s , t h e c o m b u s t i o n c h a m b e r A a n d c o m b u s t i o n c h a m b e r w i l l re p e a t t h e i r s t r o k e c y c l e s b y t u r n ,an d th e o sc i l la t in g mech an ica l p o wer can b e ex t r ac ted


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Z H A N G S h i m i n ( ? & ) et a l : Novel Micro Free-Piston Swing Engine and 3 83

f rom the o u tp u t sh af t co n t in u o u s ly . One cy c le w i l l bec o m p l e t e d f r o m Fig. 2a to Fig. 2f, and the n ex t cy c lew i l l be s tar ted f rom Fig. 2a a g a i n .

T h e M F P S E s i m p l i f i e s e n g i n e t i m i n g c o n t r o l andt h e r e is no n e c e s s i t y to use any v a l v e . M o r ei m p o r t a n t l y , it i n c r e a s e s the in teg ra tab i l i ty of thes w i n g - p i s t o n e n g i n e s y s t e m . The e n g i n e t i m i n g c o n t r o lc y c l e for gas e x c h a n g e and ig n i t io n is i l lu s t r a ted inF i g . 3. The ig n i t io n swi tch is on w h e n e v e r the top d e a d

c e n t e r is r e a c h e d .It is v ery c lea r th a t the w o r k i n g p r o c e s s of the

M F P S E is dif ferent f rom that of the M I C S E [ 6 ] , ev ent h o u g h t h e y h a v e a s i m i l a r a p p e a r a n c e . The f o r m e r is ap a r a l l e l t w o - c y l i n d e r , t w o - s t r o k e i n t e r n a l c o m b u s t i o ne n g i n e , and the l a t te r is a four cylinder , four s troke in-t e r n a l c o m b u s t i o n e n g i n e . The d i f f e r en ces of s t ru c tu re ,t i m i n g c o n t r o l m e t h o d , and w o r k i n g p r o c e s s r e s u l t ind i f f e r en t ch arac te r i s t ics and p e r f o r m a n c e .

(a ) (b) (c)

^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ' ^ " ] } ^ ^ ^ ^ ^ ^ j p

(d ) (c) (f)Exhaus t f low *~ In take f lowS cav en g e f l ow ^ ^ M o v i n g d i r ec t io n of the swing arm

Fig. 2 M F P S E w ork i n g p roces s

1.3 C h a r a c t e r i s t i c sT h e f o l l o w i n g a d v a n t a g e s are o b v i o u s for the M F P S E .

1) The s t ru c tu re of the M F P S E is s i m p l e . The o n l ym o v i n g p a r t is the s w i n g arm, w h i c h s e r v e s s i m u l t a n e o u s l y as the s e a l i n g w a l l b e t w e e n c h a m b e r s and as them e c h a n i c a l e n e r g y - e x t r a c t i n g c o m p o n e n t . I n s t e a d ofe x h a u s t v a l v e s and a s s o c i a t e d d r i v i n g m e c h a n i s m s , theM F P S E u s e s i n l e t p o r t s , e x h a u s t p o r t s , and s c a v e n g i n gp o r t s to fur ther s implify its s t ru c tu re . Mo reo v er , th e reis no r e e d v a l v e e x p o s e d in the c o m b u s t i o n c h a m b e r s .Th e sy s tem re l iab i l i ty is g r e a t l y i n c r e a s e d .

2 ) Th ere are l e s s v ib ra t io n co n cern s f ro m theM F P S E u n i t , b e c a u s e the o n ly mo v in g p ar t , the s w i n ga r m , can eas i ly be b a l a n c e d d y n a m i c a l l y . M o r e

i m p o r t a n t l y , the en erg y r e leased f ro m the c o m b u s t i o np r o c e s s is co n v er ted d i r ec t ly in to the p u r e m o m e n t u me n e r g y of the output shaf t ; no s ig n i f ican t r ad ia l andax ia l f o r ce co mp o n en ts ex is t d u r in g en g in e o p era t io nth a t co u ld cau se the d e v i c e to v i b r a t e .

3 ) The M F P S E w i l l h a v e a b e t te r ex te rn a l - lo ad (ex-t r ac t in g en erg y lev e l ) ch arac te r i s t ic b ecau se of itsu n i q u e s w i n g m o t i o n o u t p u t . One p a r t of th e en erg y re-l eased f ro m the c o m b u s t i o n p r o c e s s w i l l be c o n v e r t e din to k in e t ic en erg y of the s w i n g arm first; the o t h e rp ar t w i l l be ex t r ac ted f ro m the s y s t e m and the r e m a i n in g p ar t w i l l be c o n v e r t e d b a c k to the s y s t e m as the po-t en t ia l en erg y of the g ases in s id e the c o m p r e s s i o nc h a m b e r . W h e n the ex te rn a l ex t r ac t in g en erg y lev e ld e c r e a s e s , it wil l in c rease the e n e r g y c o n v e r t e d b a c k toth e sy s tem, th e reb y in creas in g the p r e s s u r e of the


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c o m p r e s s i o n c h a m b e r a n d t h e c o m p r e s s i o n r a t i o .4 ) A l m o s t a l l -m a j o r c o m p o n e n t s o f t h e M F P S E i n

v o l v e t w o - d i m e n s i o n a l p l a n a r d e s i g n w i t h s i m p l eg eo metr ic sh ap es . Th ere a r e v ar io u s way s to b u i ldt h e m . T h e c o m p l e t e s y s t e m c a n b e m a d e i n m a n y dif-f e r en t s izes acco rd in g to th e b es t co s t -p er fo rman ce

c h a r a c t e r i s t i c s , a n d d e v e l o p e d b a s e d o n h o w m u c h o fth e ex t r ac t in g en erg y i s n eed ed .

5 ) Th e co n t ro l sy s te m is v ery s im p le b ecau se n o so len o id v a lv es a r e n eed ed . Th e t imin g co n t ro l f o r g asex ch an g e i s d ec id ed b y th e p o s i t io n o f th e swin g a rm.

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I g ni ti on s w i tc h o nFig. 3 MF PS E t iming control cycle ("Ex." represen t s the exhau s t proces s , and "Sc." represent s the scaven ging pr oces s )

C o m p a r e d w i t h o t h e r m i c r o p o w e r g e n e r a t i o nsy s tems , i t s eems th a t th e MFPSE is a mo re p rac t ica lap p ro ach fo r ach iev in g ro b u s t , h ig h en erg y -d en s i ty ,a n d m i n i a t u r i z e d p o w e r g e n e r a t i o n s y s t e m s .2 Prototype Fabrication and

Experimental Bench Bui ldIn o rd er to v a l id a te th e f eas ib i l i ty o f th i s n ew co n cep to f mic ro f r ee -p is to n swin g en g in e , a p ro to ty p e w asfab r ica ted , an d an ex p er imen ta l b en ch u n i t was b u i l t .2 . 1 P r o t o t y p e f a b r i c a t i o nF o r m a n u f a c t u r e , w i r e e l e c t r i c a l d i s c h a r g e m a c h i n i n g( EDM) was ad o p ted to cu t th e cav i ty an d th e o u t l in e o fth e swin g a rm; th e scav en g in g p o r t s were a l so mad e b yE D M . T h e g e o m e t r i c p a r a m e t e r s w e r e d e s i g n e d w i t hre f e r en ce to t r ad i t io n a l two - s t ro k e cy c le en g in es in th eM F P S E p r o t o t y p e [ 8 ~ 1 0 ] . So me d ef in i t io n s o f th eg eo metr ic p aramete r s a r e i l lu s t r a ted in F ig . 4 . d\ is theb ase d iamete r o f b ase cav i ty ; d 2 i s th e h in g e d iam ete ro f sw in g a rm; a\ i s th e b ase cav i ty an g le ; a 2 is thein c lu d ed an g le o f th e swin g a rm; a 3 i s th e in c lu d e dan g le o f ex h au s t p o r t ; h i s th e h e ig h t o f th e ex h au s t

p o r t . Th e th ick n ess o f th e swin g a rm i s 1 5 m m ; th ewid th an d r ad iu s o f th e t r an s fe r p o r t a r e 8 m m an d7 mm, r esp ec t iv e ly ; an d th e d iamete r o f th e in tak e p o r ti s 6 mm. A f ab r ica ted swin g a rm i s i l lu s t r a ted in F ig . 5 .

Fig. 4 Def ini t ions of the geometric param eters(d\=45 m m , d 2=3 6 m m , i = 1 4 4 , r / 2= 36 , a 3 = 1 8 ,h=17 m m )

2 . 2 E x p e r i m e n t a l b e n c h b u i l dTh e MFPSE is fu e led b y g aso l in e ; an ig n i t io n sy s temmu s t a l so th ere fo re b e d ev e lo p ed fo r th e ex p er imen ta l

E

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TaepA

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Z H A N G S h i m i n ( ? & ) e t a l : Novel Micro Free-Piston Swing Engine and 3 8 5

Fig. 7 Expe rimen tal bench uni t of the MF PS E (Out l ined i m e n si o n o f t h e M F P S E : 50 m m X 5 0 m m X 3 5 m m )

2 . 3 A n a l y s i s

Fig. 5 A fabricated swing armb en ch u n i t . Th e ex p er im en ta l ig n i t io n sy s tem ( F ig . 6 )co n s is t s o f an en co d er , an F -V mo d u le , two ig n i t io nmo d u les , two co i l s , an d two sp ark p lu g s . Th e swin gm o t i o n o f t h e M F P S E i s c h e c k e d b y t h e p h o t o e l e c t r i cen co d er , wh ich i s co n n ec ted to th e o u tp u t sh af t b y ap las t ic co n n ec to r . Th e p h o to e lec t r ic en co d er p ro d u cestwo s ig n a ls , n amed s ig n a l A an d s ig n a l B , a r e sen t toth e F -V mo d u le , wh ich can co n v er t th e f r eq u en cy o fth e d ig i ta l s ig n a l in to a co n t in u o u s v o l tag e s ig n a l . Nex t ,th e v o l tag e s ig n a l i s f ed to o n e o f th e ig n i t io n mo d u lesdirectly , and i ts reversed s ignal is fed to another .F in a l ly , th e h ig h v o l tag e i s f o rmed in each co i l , an d th esp ark i s g en era ted a t th e co r r esp o n d in g sp ark p lu gw h e n e v e r t h e s w i n g a r m r e a c h e s T D C . T h e m i c r ocarb u re to r u sed in th e MFPSE is a se t as semb led o n amo d el en g in e fo r a mo d e l a i rp lan e . Th e co m p le te dex p er imen ta l b en ch u n i t i s p r esen ted in F ig . 7 .

Coil

P h o t o elect r i ce n c o d e r

Signal Ai J T J T J LJUUlSignal

LH M F P S E

F -Vmodulel

h A / WW A

Ignit ionm o d u l eIgn i t ionm o d u l eA

Coil AFig. 6 Schem at ic diagram of igni t ion sys tem

Fro m F ig . 7 , i t can b e n o t iced th a t th e re a r e n oex p er imen ta l sen so r s f ix ed fo r tes t p u rp o ses ; th e r easo nis th a t th e o r ig in a l g o a l o f man u fac tu r in g th e p ro to ty p ean d ex p e r ime n ta l b e n ch u n i t i s ju s t to v a l id a te th efeas ib i l i ty o f th i s ty p e o f micro - swin g en g in e . I t i s a l soo b v i o u s t h a t a n M F P S E d e s i g n e d b y m e a n s o fco mp ar iso n i s imp o ss ib le to wo rk a t i t s o p t imal s ta te .Th u s , i t i s n o t n ecessa ry to tes t th e sy s tem th o ro u g h lyin i t s p r esen t fo rm.

3 ConclusionsTh e main p u rp o se o f th i s wo rk i s to v a l id a te a n ewc o n c e p t o f a m i c r o f r e e - p is t o n s w i n g e n g i n e ( M F P S E ) .T h e p a r a m e t e r s o b t a i n e d b y i n t r o d u c i n g t h e d e s i g nme th o d u sed in t r ad i t io n a l two - s t ro k e cy c le in te rn a lc o m b u s t i o n e n g i n e s w i l l n o t re s u l t in t h e M F P S Ewo rk in g a t an o p t imal s ta te . Th e su ccess fu l r ea l iza t io nan d o p era t io n o f th e p ro to ty p e a r e en co u rag in g , a n dfu r th er s tu d ies o n i t s co mb u s t io n p ro cess an d scav en g i n g p r o c e s s , a s w e l l a s t h e t h e r m o d y n a m i c s a n d t h ef lu id d y n amics an a ly ses , a r e b e in g ca r r ied o u t . Mo reo v er , f ro m th e s t ru c tu re an d th e o p era t in g ch arac te r i s t ics o f th e MFPSE, i t i s a l r ead y c lea r th a t th e MFPSEis wor thy of fur ther s tudy, and that i t has the potentialt o re a l i z e p r a c ti c a l m i c r o p o w e r g e n e r a t i o n s y s t e m s .R e f e r e n c e s[1] Spear ing S M, Chen S . Micro-ga s t urb ine engine mater i

als and st ructures. In: Ceram. Eng. Sei . Proc. Westervi l l :A m e r i c a n C e r a m i c S o c , 1 9 9 7 : 1 1 - 1 8 .


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[2] Wal ther D C. ME M S oppor tuni t i es i n comb ust ion dr ivenpower genera t ion sys t ems, h t t p : / /mae .eng .uc i . edu/ seminar s/ w a l t h e r a b s . h t m l , 2 0 0 2 .

[3] Fernand ez-Pel lo A C. Micropow er genera t ion us ingcombust ion: I ssues and approaches . I n : Proceedings of t heCombust ion Ins t i t u t e . USA: Combust ion Ins t i t u t e , 2002:8 8 3 - 8 9 8 .

[ 4] J i a n g C , P r e w e t t D , W a r d C L , et a l. D e s i g n o f amicro Wankel r o t ary engine for MEMS fabr i ca t ion . I n :P r o c . S P I E I n t . S o c. O p t . E n g . U S A : S P I E - In t . S o c . O p t .E n g . , 2 0 0 1 : 5 4 -6 0 .

[5] Me hra A, Wai t z I A . Develo pme nt of a hydrogencombu stor for a microfabr i ca t ed ga s t urb ine engine . I n :Technica l Diges t , Sol id-Sta t e Sensor and Actua torWorkshop. Hi l t on Head I s l and: Transducer Res . Found,1998: 3 5 - 4 0 .

[6] Da hm W A , Ni J, Mij i t K, et al . Mi cro internal c om bus t ionswing engine (MICSE) for por t ab l e power genera t ionsys t ems (A IAA Pa per 2002 -0722) . I n : 40 th A erospac eSciences Meet ing and Exhib i t . Reno, NV, USA, 2002.

[7] Wa ng J insong, Zhan g Shimin . A two- s t roke cycle microf r ee-p is ton swing engine . C hinese P at ent , 0 211708 1.9 .( i n Chinese)

[8] Hey woo d J B , Sher E . The tw o- s t roke cycl e engine : I t sdevelopment , opera t ion , and des ign . Ann Arbor : Taylor &Franci s I nc . , 1999: 155-207.

[9] Hey woo d J B . I n t erna l Combus t ion Fund amen ta l s . N ewY o r k : M c G r a w , 1 9 8 8 : 2 0 5 - 2 7 0 .

[ 1 0] G o r d o n . D e s i g n a n d s im u l a t io n o f t w o - s t ro k e e n g i n e s .War rend ale : Soci e ty of Autom ot ive Enginee r s , I nc ., 1996:4 1 5 - 4 6 2 .

Olympic Logist ics Symposium Garners Global Input for 2008 GamesT h e f i rs t O l y m p i c L o g i s t i c s S y m p o s i u m j o i n t l y s p o n s o r e d b y t h e U n i v e r s i t y o f N o r t h C a r o l i n a a n d T s i n g h u a U n i v er s i ty o p en ed o n Feb . 2 5 , 2 0 0 5 , b r in g in g to g e th er mo re th an 1 0 0 d o mes t ic an d fo re ig n lo g is t ics ex p er t s to d i scu sst h e l o g i st i c a l c h a l l e n g e s p o s e d b y t h e 2 0 0 8 O l y m p i c G a m e s .

T h e e x p e r t s w e r e f r o m g o v e r n m e n t s , u n i v e r s i t i e s , a n d a c a d e m i c r e s e a r c h i n s t i tu t i o n s t h r o u g h o u t t h e w o r l d .D iscu ss io n s cen te r ed o n su ch to p ics as h o w lo g is t ics en te rp r i ses in th e C h in ese cap i ta l an d th ro u g h o u t th e co u n

t ry w i l l d es ig n ap p ro p r ia te lo g is t ics p lan s fo r th e Games ; h o w ad v an ced tech n o lo g y wi l l b e ap p l ied in lo g is t ics ; an dh o w th e lo g is t ics ex p er ien ce o f o th er co u n t r ies can b e p u t to u se in th e o rg an iz in g o f th e 2 0 0 8 Games .

In 2 0 0 4 , th e En g in e er in g De p ar t me n t o f Ts i n g h u a o rg an ize d a team o f r esea rch er s to seek so lu t io n s to th e lo g is t ica l i s su es su r ro u n d in g th e u p c o m in g Ga me s . Th e d ep ar tm en t h as tak e n p ar t in th e o ff ic ial p lan n in g p ro jec ts , an dh a s r e c o m m e n d e d a n u m b e r o f p r o f e s s o r s t o w o r k f o r t h e B e i j i n g O l y m p i c C o m m i t t e e .

To p ro mo te th e O ly mp ic- r e la ted lo g is t ics r esearch p ro jec ts , Ts in g h u a Un iv er s i ty w i l l e s tab l i sh a lo g is t icsr esea rch cen te r w i th Un iv e r s i ty o f No r th C aro l in a an d p lan to h o ld th e lo g is t ics sy m p o s i u m an n u a l ly u n t i l 2 0 0 8 .

T s i n g h u a V i c e P r e s i d e n t K a n g K e j u n d e l i v e r e d a s p e e c h a t t h e o p e n i n g c e r e m o n y .

( F r o m h t t p : / / n e w s . t s i n g h u a . e d u . c n )

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