Ke y wor ds :r a ilwa ys , j oi ntga poft her a i l s ,e l e c t r oma gne t i cs e ns or ,vol t a gede t e c t i ngt yper a il j oi ntga ps e ns or ,e ddy c ur r e n t .

Me mo i r sofNa ga noNa t i o n a lCo l l e geo fTe c hno l o gy,No. 3 5 ( 2 0 0 1 ) 2 9

Electromagnetic Measurement on Singular Joint Gap of the Rails

Seiichi WATANABE Tsutomu MIZUNO Shigemi ENOKI and Hajime YAMADA

Thi spa pe rde s c r i be st hemea s ur e me ntr e s ul t sofanor ma lj oi ntga pa ndas i ngul a rj oi ntga poft her ai l s us l ngVOl t a gede t e c t i ngt yper ai l j oi ntga ps e ns or .I nt hec a s eofas i ngul a rj oi ntga p,t hem i ni mum va l ueofa J Ol ntga pi sa bl et obeobt a i ne dbyc ompa r i ngt heout putvol t a geort wode t e c t i ngc oi l st ha tpl a c e di tt owa r d t her a ilw id t ha ndt heme a s ur e me ntr e s ul t sofanor ma l j oi ntga p.

Ke y wor ds :r a ilwa ys , j oi ntga poft her a i l s ,e l e c t r oma gne t i cs e ns or ,vol t a gede t e c t i ngt yper a il j oi ntga ps e ns or ,e ddy c ur r e n t .

1 . I nt roduct i on

A

n e l e c t r o ma g ne t i c s e ns or' i s a lr e a d y us e d i n a me a s ur e me ntofr a ildi s pl a c e me ntbe c a us eme a s ur e me nt i spos s i bl ei na nywe a t he rc ondi t i onl 1 日2 ] .Thea u t hor s c ons i de r e da boutame a s ur e me n tme t hodofj oi n tg a pof t hem il sus i n gi mpe da nc ede t e c t i n gt y pea ndvo l t a ge de t e c t i ngt yper a i lj oi ntga ps e ns orbya i r ‑ c or ec oi l sf ♭r r a il j oi ntga pme a s ur e me ntl 3 日4 ) .Thi spa pe rde s c r ibe d a sf o l l ows :( 1 )s t r uc t ur eofvol t a gede t e c t i ngt y per a il j oi n tga ps e ns or ,a ndm

nngme t ho dofs i ng u l a rj o i nt g a po ft he r a il s ;( 2)me a s ur e me ntofs i ng ul a rj oi ntga pof t her a i l s .

2 . St ruct ur eofvol t agedet ect i ngt ype rai lj oi ntgaps ens or

Fi g.1s howsas t r uc t ur eofvol t a gede t e c t i ngt yper a il j oi ntga ps e ns or . Thevo l t a g ede t e c t i ngt yper a il j oi n tga p

s e ns o ri sc o mpr is e d f o urde t e c t i ng c oi l sunde rone e xc i t I ' ngc oi l . He r e ,aj oi n tga poft her a il si sme a s ur e dby

Ap a r tO ft hi s

s e a r c hwa sa c c o mp l i s h e db yt h ee d u c a t i o n r e s e a r c hs p e c i a le x p e n d i t u r eo f1 9 9 9t e r m.

*IRe t o u c hc o r r e c t i o no fT hi r dEu r o p e a nCo n f e r e n c eo n Ma g n e t i cS e n s o r sa T L dAc t u a t o r s ; J u l y1 9 ‑ 2 0 , 2 0 0 0 .

*2Re s e a r c hA ss i s t a n t , De p a r t me n to fEl e c t r i c a lEn g in e e r i n g

*3A ss o c i a t ePr o f e s s o r ,Fa c u l t y o fEn g i n e e r i n g ,S h i n s h u Un i v c r s i t y

*4S hi n k a waSe n s o rT e c h n o l o g yhc .

*5Do c t o r sI n t e ma t i o n a lCo l l a b o r a t i o nI n s t i t u t e Re c e i v e dS e p t e mb e r2 8 , 2 0 0

( b )S i d ev i e w

Fi g .1 S

r

c t u r eo f v o l t a g ed e t e c t i n gt y p er a il j o i n tg a ps e n s o r ( u n i t: mm) .

us i ngt wode t e c t i ngc oi l sAa J l d B.

Theou t pu tvol t a ge ,V &a ndVb( V) ,oft hede t e c t i ng c o i l sAa ndBa r eg iv e nby( I )a nd( 2) .

V 8 ‑ ‑N

. ^{笠 ‑‑N}

v b ‑ ‑ N d 笠‑ ‑ N d

( 1 )

( 2)

3 0 _{Se i i c hiWATANAB ETs ut omuMI Z UNO,Shi ge m i ENOKT ,Ha j i meYAMA DA}

whe r e￠.i st hen u x( W b ) ofde t e c t i ngc o i lA,N di st he nu m b e roft u msofde t e c t i ngc oi l ,B

i sd i el i nka gef l ux de n s i t y ( T)ofde t e c t i ngc o i l A,ndi st heuni tme t hodl i ne ve c t o rofa r e aofde t e c t i ngc o i l , Adi st hea r e a( m

of de t e c t i ngc o i

i st het i me( S ) ,￠bi st hef l u x( Wb) of de t e c t i ngc oi lB,a ndBbi st hel i nka genu xde ns i t y( T)of d e t e c t i ngc o i l B.

Theout putvol t a ge ,V&a nd V b ,i nc r e a s ei nt hec a s et ha t t

hede t e c t i ngc oi l si si nt heu ppe rpa r tofaj oi ntga p.

Be c a us e ,nu xoc c u r r e db ye d d yc ur r e n tde c r e a s e si nt he uppe rp

r tofaj oi n tga p.

Fi g.2s howsamode lofas i ngul a r j oi ntga poft he r a i l s . A j oi ntga p , 6 ,i sde f i ne dw it h t hem ini mum va lue i ni n t e r va lofm i lA a nd B . A n e dgef a c eofm i l A i s ve r t i c a lt o wa rdal ong it udi na ldi r e c t i onofr a i l . A n e dge f a c eofr a ilBi ss ha ve do bl i q u e l ys howni n Fi g.2( a ) .I n t

hec a s et ha ta n e d gef a c eofm i IB i sve r t i c a lt owa r da l ongi t udi na ldi r e c t i onorr a i li sc a l l e dbynom a lj oi nt ga p,a nda n e dgef a c eofr a iIB i ss ha ve dobl i que l yi s c a l l e dbys i ngul a r j oi ntga p.

3. M e as ur ngmet hodofs i nguhrj oi ntgap of t he r ai l s

Fi g. 3 s howst heme a s ur e me ntbl o c kofs i ngul a rj oi nt ga poft her a il sus i ngvol t a gede t e c t i ngt yper a il j oi ntga p s e n s or .Out putvol t a ge ,V & a nd V b ,Ofde t e c t i ngc oi l s A a

ndB,r e s pe c t i ve l y ,a r eme a s u r e da tl i R･ o f f,

7 mm ,

r a ildi s pl a c e me n t ,

0mm,ke que nc y , I ‑1MHz ,a nd e xc i t i ngvol t a ge ,V c= 20Vwh e nt he ydi s pl a c ei tt owa r d al o ng it udi na ldi r e c t i onofm i 1 ( i nt hedi r e c t i onof y‑ a xi s ) .

4. M eas ur ementofs i ngul a r j oi ntgap oft her a il s

Fi g. 4 s howst hec ha r a c t e r is t i c sofou t putvol t a ge ,V &

a

nd V b ,VS . di s pl a c e me n t , ya tSe0 m m ( m i lAa ndr a ilB

O) ) F r o nt v ie w ( C )Si dev ie w Fi g . 2 Amo d e l o fs i n gu l a r j o i n tga po f t h er a i l s( u ni t: mm) .

( a )Fr o n tv i e w ( b )Si d ev i e w Fi g.3 Me a s u r e me n tbl o c ko fs i n g u l a rr a ilj o i ntg a pu s l n g v o l t a g ed e t e c t i n gt yp e m il j o i n tga ps e n s o r( u ni t: mm) .

De wc t i ngc

旦1｢ 上 l＼

l 35 t l

V c .

＼‑

⊂ >

〜 l l ヽ ■ 一 ′

O h l 芯J . 丈 l

l l. I 一 く⊂ N ヽ ‖ 一 ー . ● } J t ′ >

Ra i l a †

ヽ

h) q Ap tre .A .払 ｡lt O^ tn d l nO

7 . 8

‑1 00 ー 5 0 0 5 0 1 00 Di s pl a c e me n t , y ( mm)

Fi g . 4 Ch a r a c t e r is t i c so fou t p u tv o l t a g e ,V Aa nd V b ,V S . d i s p l a c e me nt , y( me a s u r in gc o n di t i o n:

‑7 m m, x ‑0m m, f=

1 M

z , V c ‑2 0V,6=Omm) .

a r ec ont a c t i ng) . Out putvol t a ge , V&a ndVbi nc r e a s e si nt he

uppe rpa r tofaj oi ntga p. Ther e s ul ti ndi c a t e di nt heuppe r

pa rtofaj oi ntga p

a tout putvol t a ge ,V a a ndVba gr e e s

El e c t r o ma gn e t i cMe as ur e me ntonSi ngul arJ oi ntGa poft heRai l s f o rt hemos tpa r[a nd V .< VbOnt hes i ngul a rj oi ntga pl n

t h er a il( S=3mm)

Thi sdi f f e r e nc eme a ns

a taj oi n tga p i nt hel oc a t i onofde t e c t i ngc oi l a i s 1 . 8 mm bi gge rt ha n t h a ti nt hel o c a t i o nofde t e c t i ngc o i l A.He r e ,t hevol t a ge c ha ngeofade t e c t i ngc oi l sAa nd B , V.a ndVba r ede f i ne d l w

it hAV&a nd AV b .

Fi g. 5 s ho wst hec ha r a c t e r i s t i c sofvol t a gec ha ng e ,AV . a nd AV b ,VS . j oi ntga pbe t we e nt her a i l s ,6. Thevol t a ge c h a nge ofa de t e c t i ng c o i lB ,AV b ,i s i nc r e a s l ng I n c o mpa r is on w it h t hec ha ngeoft hevol t a gec ha ngeof de t e c t i n gc o i l A,AV & ,a c c or di ngt ot hec ha ngeofaj oi n t g a poft her a il s .

8 6 4 2 1 0 0 0 0

(>) .A V .

!03 的u

9ta p

3tr eq

8 6 4 2 1 0 0 0 0 0 h ) qA V . g t !0 0 3

aIa P J

Su t:t

93 ｡) 70

0

4 8 1 2

J oi n tg a p,♂ ( mm) ( a )Vo l t a g ec h a n g eo fd e t e c t i n gc o i l

AV .

1 6

0 4 8 1 2

J oi n tg a p,♂ ( mm) ( b )Vo l t a g ec h a n g eo fd e t e c t i n gc o i l

Fi g. 5 Cha r a c t e r i s t i c so fv o l t a g ec ha ng e

AV .a ndAVb , V S . j o i n t g a poft her a il s , 6( me a s u r i n gc o n d i t i o n: I ‑7 mm, x ‑0 mm , f‑

1MHz ,

V) .

31 Ass hown i nFi g.4,mi ni mum val ueoraj oi ntga p ,

6 C( m) ,i sg ive nby( 3) /

6 C =

‑ S ( i

a)

2(

x b 6 8 ^‑ x A S b ) + W

3a)

2(

^{( 3)}

whe r e6&i st hej oi ntga p( m)unde rt hede t e c t i ngc o i l

,xAi s t

hel oc a t i o n( m)ofde t e c t i ngc o i lA, wi st hew id t h( m)of r a iI , x

i st hel oc a t i o n( m)ofde t e c t i ng c o i lB ,a nd6

i st hej oi nt g a p( m)u nde rt hed

c t i n g c o i l B.

Fr omt her es ul tofFi g. 5 , j oi ntga poft her a i l s , 6Aa nd S

( m) , a p ee xpr e s s e dwi t ht w ic ef unc t i on.

6a= 1 ･ 38×1 0 1

A

8

+ 1 ･ 39×1

‑

AV B

̲3 . 29×1 0

6

= 1 ･ 71 ×1 0 ‑

A

b

+ 1 ･ 34×1

‑

AV b

̲2. 81 ×1

‑

( 4)

( 5 ) Subs t i t ut i ng( 4)a nd ( 5 ) i n t o( 3) ,m i ni mum va l ueofa j oi ntga p , S c ,i sc a lc ul a t e dus i ngt hec ha r a c t e r is t i c s( S= 0 mm)s ho w n i nFi g . 5 . Thej oi ntga poft her a i l , 6 8 a nd 6

,

a

r ec a l c ul a t e di nt hec a s eof s ‑0 m m i nFi g .5.

Fi g. 6 s ho wst hec ompa r i s onw it hc a lc ul a t e dva lue sof j oi ntga pa ndj oi ntga poft her a il s .I ts howst ha tt hej oi nt ga port her ai l si sa gr e el ngWi t hi n ±0. 9 mm i nt hec a s e or∫‑3 mm.

( u u )

.d 亀 tu to

o a n

2^

a

U 0 6 2 2 1 1 8 4 0

0 4 8 1 2

J oi ntg a p , 6( mm)

1 6

Fi g . 6 Co mpa r is o nw it hc a l c ul a t e dv a l u eo f j o i n tg a pa ndj o i n t g a poft her a il s( me a s u r i n gc o nd i t i on: I= 7 mm, x = 0 m m, f

IMH

32 Se i i c hiWATANAB E ,Ts ut o muMI Z UNO ,Shi ge m i ENO KT ,Ha j i meYAMAD A

5. Concl us i on

l nt hi spa pe r ,i te xpr e s s e da bou tt heme t hodt ha tt he mi ni mumva lueofaj oi ntga poft her a il swa sme a s ur e d e ve ni nt hec a s eofas i nguI a rj oi n tga pb yc ompa ri ngt he me a s ur e me ntr e s ul t sofano r ma l j oi ntg a pu s i n gVol t a g e de t e c t i ngt yper a il j oi ntga ps e ns or . Thef ol l ow ingr e s ul t s we r eobt a ine d.

( 1 ) A s i ng u l 町j oi n tga poft her a il swa sme a s ur e db y t

heou t p utv ol t a geoft wode t e c t i ngc oi l st ha tpl a c e di t t o wa r dt her a ilw idt h,a ndc o ul di de nt i f y i tc l e a r l yw it ha no r ma lj oi ntga p.

( 2)n ej oi ntga pbe t we e nt hee a c hr a ilwa sa gr e e i n g wi 血i n ±0. 9mm i n仙ec a s eO r J‑3mm i nas l ng ul a r j oi ntga p oft he m il s a tl i R ･ o f

I‑ 7 m m ,r a il di s pl a c e me n t ,I=0 m m,f r e que nc y , f =

a nd e xc i t i ngvol t a g e , V c‑20 V.

Ref er ences

l l ]S.Ki s hi mo t o:No n‑ c on t a c tme a s ur e me ntoft her a il di s pl a c e ･ me n tbye dd yc ur r e nts e ns o r ,J o u ma lofJ a pa ne s e Soc i e t yf ♭ rWon ‑de s t mc t i yeI ns pe c t i on, Ⅵ) 1 .40,No･9 , pp.62 4 ‑630 ,1 99 1 ･

( 2 ]Y.Sud a ,j LNa ga t o ,K.Tokuo kaa ndS･Mi ur a:Ne w Ra il , J a p a n Ra il r oa dI ns t i t ut i o nSoc i e t y, p. 485 ,1 99 7.

[ 3 ]S. W

a be ,T.Mi z u n o,T.Na k a j i ma ,S･Eno k i ,KI Th ke s hi t a ,S.Ki s hi mo t oa ndH.Ya ma d a:I mpe da nc e c ha r a c t e r is t i c s of pr obe c oi l f o r m il j oi n t ga p me a s u r e me n t s ,J our na l oft he Ma g ne t i c sSoc i e t y of J a p a L l , Vol . 24, No. 4‑2,pp. 8 63‑ 8 66, 200 0.

[ 4 ]S.Wa

a

a l) e:St ud yone l e c t r oma gne t i cs e ns o r sf o r no n<o nt a c tme a s ur e me n tofr a ilwe a r in gde pt h a ndr a il j oi ntga p,Doc t o r s The s i s ,Shi ns hu Uni v e r s i t y ,pp･

8 2 ‑1 0 4,200 0.