'rIT1.E Q F THE INVEWTION
A m T m i O m R . .
TECHNICAL FIELD
[QOO 1 1
The present invention relates to an .aut~-tensionewr hich moderately maintains the
tension of a belt.
I3ACKG:ROUND ART
[oooz]
Hitherto, far ,example,.i n .an: auxiliarym achine :drive .syst&~~ i 'af vehicle .or
t1ii like, an auto-tensioner has been employed. in order to prevent a beit slip at the Eime
whsn the tension of ,a belt is changed.
[0003]
For example, an auto-'knsioner described inpatent Document I has a gtatiamy
member, a roeatable member which is supp~rtedto be able-tor owe relative to the
.Stationary member, a d a coil spring which hiases the rotatable member to rotate relative to
the statinnay member. A pulley on which.-&be lt is wound is mounted to Ole rotatable
member. The stationary member and the rotatable member have outer cylindrical
.purtions f6r accommodating '&e coil spring therein. Further, on the insides of the outer
.cylindricalp orti~no fthe statbntuy member and the outer cyfindrical portion of 'the.
rc~~atabmlee mber, in addition to the coil Spring,.i iictian members .are mauged for damping.
..the os'cillation of the rijtatable. member, The friction member$ are all owed to .slide on the
stationary member or the rotatable member when the rota-bke member romks.
yo004 1
During the use of'xhe~ autb-tensioneq.muddwy arm . e r n eo il3, .and the Iike.s tick to
the outer surface 0 f . h stationary member or the rotatable member and idhate idta the
inside through the gap between the stationary member and h rotatable member. When
the muddy water and the like infiltrate bewen the- fiotion member made of a rubber -or a
spiyhetic resin and a sliding object (he stationary member or the rotatable member), wear
ofr he tiiction member is accelerated, and a--dampinge ffect.i s reduced due to a reduction in
braking force. Moreover, there was cqnc-ern that the infiltrating muddy water and the like
may have an adverse effect on the durability df members ather than the friction members.
[OOoj J
As the auto-tensiuner which pkeven@. the;inf3tration of muddy water and lhe like,
kr.:cxample, there is.. oned isclowd in Patent Do~ufzlen.t2 . The auto-tensioner has a
structure in which a lip is furmed to extend outward h m a part of the peripheral edge of
an crpening podon of a stationary member (iensioner cup) and an outer race portion of a
rotaxable member (tensioner am] extends to cover the lip, thereby suppressing the
infiltration of muddy water and the like. The lip is disposed so as to be on the upper side
5 when the engine is mounted. In addition, between the inner peripheral surface of the
opening portion of the stationary member and the outer peripheral surface of an inner race
portion of the rotatable member, a friction member (damping band) is dispsd over the
entirc periphery.
L RELATED ART DOCUMENTS
PATENT 1 .Tl'liRAW,
t0006J
Patent D o c ~ m1t: JP-A-2010- 11 2549
Patent Document 2: JP-A-2004-204937
. .
SUMMARY OF THE ~WNTIOFY
PROBLEMS TO BE SOLVED BY THE INVENTION
[OQ07]
However, in the structure of Patent Do~ument2 , the lip which protrudes outward
L 5 from the peripheral edge of the opening portion of the stationary member acts as a bdwark
and can impede the infiltration of muddy water and the like, but any guide mms for
actively discharsing ruddy warn and the like is not provided. l%erefore. muddy water
and the like move downward along the outer peripheral surface of the stationary member
and then easily collect between the lower portion of the outer peripheral surface of the
stationary member and the lower portion of the outer race portion of the rotatable membtr,
ard thus there is concern that this may then infiltrate into the inside.
[uooal
Here, an object of the present invention is to provide m auto-tensioner capable of
suppressing the infiltration of muddy water and the like inlo the inside and actively
, I. coliecting and smoothly discharging the muddy water and the like.
MEANS FOR SOI,VING THE PROBLEMS
[oU09]
An auto- tensioner of a first aspect of the present inventioh includes:
- . a stationary member having a fust cylindrical portion;
a rotatable member which has a second cylindrical partion of which at leasst a part
is disposed to overlap the 5~3c%y lindrical portion in aradial dire~+on, md is support&
retatably relative to he stationary member;
a coil spring which is wccomadaned gn insides of the first cyhdrical portion and
the second cylindrical portion and has one. end lackkd to the stationary member anxZ ~e
other cnd locked to the rotatable memb;.-and
a drainage mechanism provided at a boundaiy part of the h t cylindrical pa&on
5 m d ' the second cylindrical .portion,
in which the drainage mechmism includes
a wter configured. by a gap betwee~~,oaunt er peripheral surfaceof tbe.first
gylindrical portion and an outer peripheral surface of .the second cylindricalportion and
being open along a peripheral direction,
. ,
,. l. ! a water passzge which iq configured by &..gapb etween a water caUwtin,g g r o w
i2rmcd along 'the peripheral direction in the outer peripheral .surface oE ane: of the:tw~
Cpli,nddcal partions and the ather cylindrical partion, and comunicates with the Water
inlct, and
at least one drainage: port farmed in a peripheral wail on an outside in the-radial
7 -
-2 directinn of fhe water passage.
[oo r o]
In this configuration, in a case where-the auto-tendaner is disposed so that the
cylinder axiaI direction thereof is in a direction other than the upward apd downward
djre~tiun( for example, substantially in a horizontal direction), muddy water a dt he like
:: :! :fluwing into the water inlet Bow into thewater piassage provided on the ,inside in the radial
direction of.t he .water inlet,,m uve.do~4warddb ng thk .periphk.;al direction in the water
passage, and thereafter, me dihcharged to the o.ut@e from the &&age port. Therefife,
the. coiIee;ted muddy wafer md :$he like dan be smoothly diwharged .while suppre.ssing.t~
.Idillratibn of the muddy water .and the likeinto the, inside pf the autg-tensioner.
L :. [Qtlli)
According io .the auto-tensionex :of a: sewnd aqeot gf the present invention, iil the
.first aspect, the water c,oi:lectingg roove has a depth dimction in a cyhder mid direction
of the e ylindrical portion, and 'the cylindrical partian .of the:.twa sylhdr3ca! portions, in
\$hi& no water cdllecting groove is formed, has a tip end'portion inserted into ;the water
i . n collecting groove.
loo 121
In this configuration, since the tip end portion af the cylindricd portion in which
IIO water collecting pow is famed js inserted into the water collecting groove, the water
passage has a U shape. Accordingly, muddy wafer and tbe like flowing into the water
: inlet flow into an outside part in the radial directbn ofthe U-shaped water passage a d
rnnve downward alung the peripheral. diremion in this part. Therefore, muddy water and
the like are.less Likely to infiltrate into an inside part inthe radial direction of the Il-shqed
water pasage. Consequently, infiltration of muddy water and the Iike into the inside of
he auto-tensinner can be more reliably suppressed.
[OO 131
The auto-tensioner of a third aspect of the prescmf invention, in the first or second
5 aspect, further includes: an elastic body which has one end lacked to one member of the
rotatable member and the stationary member and tfie other end that is a free end, and
extends along an inner pipherd surface of the cyliidricd portion of the other member of
the rotatable member and .the stationary member; and a friction member which is joined
immovable relative .to the elastic body in the peripheral direction and cgmes into contact
I I-r with the inner peripheral suxface of the cylindrical portion, of the other member of the
rotatabie member and the stationary member.
[OO 141
In this configuration, when the tension of a belt is changed and the rotatable
member is rarated relative to the stationary mamber, the friction member slides on he
: :. stationary member or the rotatable member. Accordingly, the osciIIation of the rotatable
member can be suppressed and damped, hrthem~orefi~c tion forces generated between
the friction member and the sIiding object can be made a difference between the cases
where the tension of the belt is increased and decreased.
[OO 151
According to the auto-knsioner of a fourth aspect of the present invention, in any
uf thc iixst to third aspects, the drainage port communicates with a lowm ~ o d oonf the
water passage.
[OO 1.61
In this configuration, muddy water arid the like flowing into the water passage can
,< :.i be relinbl y discharged from the drainage port.
100 1 71
Accardining to the auto-tensioner of a fiRh aspect of the present invention, in the
third or fourth aspect, the drainage pat is formed in the cylindxieaf pertion of the other
member, and the friction member is not present on an inside of the cylindrical partion of
- 1 thc uthcr member in a peripheral direction mge of the drainage port.
[OOl S]
In this configuration, even in the case where muddy water and the like infiltrate
into the inside of the cylindrical portion of the o&er member fiom the drainage pofl, since
the fiction member is not present at the position that is most affected by the muddy water
: 5 and the like infiltrating from the drainage port* we= of the friction member can be
suppressed.
.BRIEF ZI ISSCRIPTTON 'OF THE DIRGWXNGS
100 1 91
[FIG I Fig. I is a perspective view of m auto-tensionex of a fnst embodiment of
the present inventiprl.
[FIG 21 Fig. 2 is a cross-sectional view of the auto-tensioner illustrated in Fig. 1.
3 FIG. 33 Pig. 3 is a cross-sectional view taken dong line A-A of Fig. 2.
[FIG 4 J Fig. 4 is a diagram of a stationary member and members mounted to Ehe
sttationary member illustrated in Fig. 1, viewed h r n the right in Fig. 1.
[FIG, 551 Fig. 5 is a perspective view of the stationary member iIIustrated in Fig. 1 .
[PIG. 61 Fig. 6 is a partiat cross-sectional view of an auto-tensioner of a
7 5 modification example of the first embodiment.
[FIG. 71 Fig. 7 is a partial crass-sectional view of an auto-tensioner of a
tnadi fication example of the first embodiment.
[PIG. 81 Fig. 8 is a putid cross-sectional view of an auto-tensianer of a
modifreation example of the first embodiment.
I T; [FIG. 91 Fig. 9 is a crossaectiand view of an auto-tensioner of a second
embodiment of the present invention-
[FIG. 101 Fig, 1 0 is a cross-smtianaI view taken along line B-B of Fig. 9.
hIODE FOR CARRYING OUT THE INVIENTION
- . [0020]
-=First Ernbndimenp
An auto-tensioner 1 according to a first embodiment of the present invention will
be described below.
The auto-tensioner 1 afthis embodiment adjusts the temion of a trammission belt
. for transmitting power of the crankshaft of an engine to auxiliary machines and is mounted
to the engine block of a vehicle.
[OOZ i]
As illustrated in Fig. L and Fig. 2, the auto-tensibner 1, includes a stationary
rnenibcr 20, a rotatable member 30, a coil spring 4, a drainage mechanism 5 0, a leaf spring
: (elastic body) 6, and a plurdity of fiction members 7. A pulley I DO on which a
transmission be11 is wound is to be mounted to the rotatable membw 20. In addition, the
rotatable member 30 is supported rotatably relative to the stationary member 20 via a shaft
8 and bushes 9. In the following description, the direstion of the rotary axis of the
ro~abblem ember 30 (the axial direction of the shaft 8) is simply referred to as an axial
. direction. Incidentally, in Fig. 2, a form of the mmding portions of the coil spring 4
and the drainage m~hanism50 viewed in backward of the line of sight from the crosssection
is also illustrated, but the other part8 are illustrated only in cross-scction. In
addition, in Fig. 6 to Fig, 8 wd Fig. 10 of a modification exmple and a sccand
embodiment described Irzter; the ssame applies.
[oozz]
The stationary member 20 is fixed to a non-ilIustrated engine block so fiat the up
1; and dom direction thereof is the upward and downwad direction (arrow X: upper
direcrion, arrow Y downward direction] shown in Fig. 2 and Fig. 4. The stationary
member 20 is constituted by an outer cylindrical podon (first cylin&ical portion] 21, an
imer cylindrical portion 22 disposed inside the outer cylindrical portion 21, a d an annular
bottom wall portion 23 connecting the outer cylhdrical portion 2 f and the inner cyhdrical
: fi portion 22. The inner cylindrical portion 22 is fixed unrotatably relative ta the shaft 8.
As illustrated in Fig. 4 and Fig. 5, substantially at the enter in the axial directicm of the
outer oylindrical portion 21, a substmthUy triangular flange portion 21 a is prbvided.
Ir>cidentdly, in the specification, "upward" and "downward" respectively mean '%vertically
upward" and "vertically downward" unless otherwise noted,
[0023]
As illustrated in Fig. 4 and Fig. 5, in tbe outer peripheral surface (specifically, the
Flange portiun 21aj of the outer cylindrical portion 21, a water coIlecting groove 21b is
fmrncd over the entire periphery. The depth direction of the water collecting groove 2 1 b
is in the axial direction, and a depth H (see Fig. 2) of the waler collecting groove 2 1b is, for
T rl: exanple, 2 to 5 m. In the case where the water collecting groove 2 1 b is too deep, the
strength of the stationary member 20 cmot be maintained, and in the case where it is too
shallow, a bction of collecting water is not achieved. Therefore, the depth of the water
collecting groove 2 1 b is preferably in the above range.
[0024]
8 . .% A As illustrated in Fig. I and Fig. 5, a cutout 21c is formed in the peripheral wall
(flange portion 2 1 a) on the outer side in the rsdial direction of the water collecting groove
2 1 b. By the cutout 2 f c, a drainage port 53 of fhe &ahage mechanism SO is configured.
As illustrated in Fig. 1 and Fig. 4, the stati~narym ember 20 is installed so that the drainage
port 53 is pasitioncd on the lower side of the water collecting groove 21 b. Aperiphmal
. . . direction range L of the drainage port 53 is prefarably a range of ZQ deg;cees (a. in Fig. 3)
each in the cIockw-ise direction and the counterclackwise direction from the position
immetliatdy below the central axis of ro&m.
[oozrl
The ratatable member 3 0 is constituted by an outer cylindrical portion (second
-, cylindrical partion) 3 1, an inner cylindrical portjoa 32 disposed inside the outer cylindrical
portion 3 I, an annular bottom wall poxtion 33 comeding h e outer cylindrical portion 3 1
and thc inner cylirrdri~apl ortion 32, and a pdley support portion 34. The pulley 10Q is
clcrachably mounted to the pulley support portioa 34.
[oms]
The inner cylindrical, portion 32 is disposed side by side to the inner cylindrical
portion 22 of the stationary member 20 in the axial dirmtirm. The inner cylin&iml
pclrtion 32 is mounted rotatably relative to the s M 8 via the bushes 9. Accordingly, the
: rotatable member 3 0 is rotatable relative tb the stationary member 20. The inner
cylindrical portion 32 has a 1-r outside diameter in the right part than that in the Ieft pw
in Fig. 2. A surface of the part with the larger outside diameter and Facing the coil spring
4 is fbrmed in a spiral shape so as ts be along the mil spring 4. Thedre, as illustrated
in Fig. 3, a steppcd portion 32a is formed ai the boundary of the start positian and the end ' :.I position of the spiral. Incidentally, in Fig. 3, iIIustr.stion of the outer cylindrid pufiion
3 1 a f the rotatable member 3 0 is omitted.
[0027]
The outer cylindrical portion 3 1 is disposed to overlap the outer cylindrical
portion 2 1 of the s a t i o n 9 member 20 in the radial direction. Specifically, the outer
. cylindrical postion 3 1 is disposed on the outer side in th radial direction af the outer
cy IindricaI portion 2 1 of the stationary member 20. In addition, the tip end portion of the
outer cylindrical portion 3 t is inserted into the inside of the water collecting groove 21 b
h m d in the outer cylindrical portion 21 of the stationary member 20. Therefore, the
gap between the water collecting groove 21 b and the tip end portion of the outer
' cyliodrical portion 3 1 of the rotatable member 30 h a U shape. The U-shaped gap
hnns a water passage 52 of the drainage mechanism 50. The water passage 52 is farmed
elver the entire periphery.
1002S?
In addition, a pat obtained by excluding the drainage part 53 from the gap
; :, between the outer peripheral surface of the auta cylindricd portion 2 1 of the stationary
member 20 and the outer peripheral s&ce of the outer cylindrical partion 3 1 of the
rotatable member 30 forms a water inlet 51 of the drainage mechanism 50. The water
inlet 5 1 is open along the peripheral direction. An interval D (see Fig. 2) of the wafer
inlet 5 1 is, for example, 1 ta 3 mm- In the case where the water inlet 5 1 is too I-, there
- 1 is a praklenl in that dirt easily infiltrates and the gap becomes dogged, and in the case
where it is roo small, dirt is likely to collect. Therefare, the intervd of the water inlet 5 I
is preferably in the above rmge.
[OU29]
The drainage mechanism 50 is for preventing muddy water and the like from
L. infiltrating into the inside of the auto-tensioner 1. The W a g e mechanism 50 is
provided at the boundary part of the outer cylindricaf portion 21 of the stationq member
20 and the outer cylindrical portion 3 1 of the rotatable member 3 0 and is constituted by the
water inlet 5 1, the water passage 52, and &e drainage port 53 described above.
t 00301
As iIlustrated in Fig. 2, the cail spring 4 is disposed inside the outer cylindrical
pofiiun 21 a£ the stationary member 20 and the outer cylindrical portion 3 1 of the rotatable
member 330. One ~ npdor tion 4a (right end portion in Fig. 2) of the cail spring 4 is locked
ir to the rotatable member 33, md the ether end portion (kit end portion h Fig. 2) is lock&
to the: maiionary membcr 20, so that the rotatable member 3 0 is biased ta rotate relative to
thc stationary member 20 in one direction. The biasing direction of the coil spring 4 is a
direction in which a tension is to be appli~dto the transmission belt wound on the pulley
1 QO.
LO03 11
As illustrated in Fig. 3, the end portion 4a of tbe coiI spring 4 presss the stepped
portion 32a of the rotatable member 30 via the leaf spring 6, and accofdingly, the end
portion of the coil spring 4 is locked to the rotatable member 30. A method of 1 o&ng the
end portion of the coil spring 4 to the statiana~m~e mber 20 is not particularIy limited-
! .) For example, the other end portion of the coil spring 4 is fitted into a groove portion
formed in the stationary member 20, or a bent end portion of the coil spring 4 is presslitted
ro a locking hole which is formed in the stationary member 20 and extends in the
radial direction or the axial direction to be locked.
COO321
As illustrated in Fig. 3 and Fig. 4, a coil spring support member 10 far suppressing
the tilt of the position of the coil spring 4 is mounted to the coil spring 4. The coil sphg
support member f 0 is interposed between the fiction member 7 and the coil spring 4 (see
Fig. 4). Incidentally. the coil spring support member 10 may not be provided
[0033]
As illustrated in Fig. 2 and Fig, 3, the leaf spring (dastic body) 6 is disposed on
the inside of the tip end side part of the outer cylindrical portion 21 of the stationary
member 20 and extends along the inner pripheral surface of the outer cylindrical portion
21. As illustrated in Fig. 3, one c3aA portion 6a of the leaf spring 6 is bent at 90 degrees
toward the inside in the radial direction and is nipped between the stepped portion 32a of
:.> the rotatable member 30 and the end portion 4a of the coil spring 4. AccordingIy, the end
partion 6a of the leaf spring 6 is locked to the rotateable member 30, An end pohon on
the opposite end to the end podon 6aof the Zedspring 6 is a free end. In additionp in the
lcaf spring 6, a plurality of mounting hdes 6b to which the plurality of friction members 7
are mounted are f~ormeds ide by side to the peripheral direction.
[0034]
The plurality of (in this embodiment, seven] friction members 7 ate arranged
bctween the inner peripheral surface of the outer cylindrical portion 21 of the stationary
member 20 and the leaf spring 6. The plurality of friction mcmbers 7 are arranged side
hy side to the peripheral direction outside a paiphaal diration range L of the drainage
porr 53. The plurality of friction members 7 are preferably arranged outside a rmge of 20
degrees (a in Fig. 3) each in the clockwise direction and the cowterdockwi~d imction
fi-om the position imrzlediardy below the central axis of rotation. The friction members 7
are filled into the mounting holes 6b farmed in the leaf spring 6 and are joined so as to be
jmmnvable relative to the Ieaf spring 6 in tho peripheral direction. The leaf spring 6 is
disposed in a state of being slightly contracted in diameter, arxd thus the friction members 7
receive a self-elastic diameter-enlarging form of the leaf spring 6 and always come into
contact with the inner peripheral surface of the outer cylindrical portion 21 of the
:. I stationary member 20. The fiction member 7 is formed to mainly contain, for ~xmpIca,
synthetic resin such as a polyami.de resin including Nyjan 66, a pal yacetal resin, a
pmlyaylate resin, a phenol resin, a p01ypbenyTene sulfide (PPS) resin, or m ultra-highmolecular-
weight polyethylene resin.
[O 03 51
*
I In a case where the tension of the transmission belt is increased, the rotatable
member 38 is rotated in the cIockwise diredon of Fig. 3 against the biasing force of the
coil spring 4. At this time, the end portion 6a of the leaf spring 6 is moved in tbe
clockwise direction of Fig. 3 (a direction away from the fiee end), and thus the leaf spring
6 is cntireiy moved in ihe peripheral direction and is deformed to be slightly enlarged in
i ; diameter. Accordingly, a force! of the friction members 7 being pressed to the inner
periphexal surface of the outer cylindrical portion 21 of the stationary member 20 is
increased, and a large frictional force is generated between the friction members 7 and the
outcr cylindrical portion 21 of the statianary member 20. The fictional force acts as a
damping force of suppressing and damping the osciUation of the rotatable member 30.
; c COO361
On the other hand, in a case whem the tension ofthe transmission belt is reduced,
the rotatable member 30 is rotated in the counterclockwise direction of Fig. 3 by the
biasing force of the coil spring 4. At this time, the end portion 6a of the leaf spring 6 is
moved in the counterclackwise direction of Fig. 3 (a direction toward free end), and
I thus the leaf spring 6 is entirely moved in the peripberd direction and is deformed to be
slightly contraevted in diameter. Accordingly, a force of the fricticrll members 7 being
pres9ed to Chc inner peripheral surface of the outer cylindrical portion 21 of the stationary
mmber 20 is decreased, and only a small fiictbnl force is generated between the friction
members 7 and the outer cylindrid portion 21 of the stationary member 20.
[0037]
=Is described above, in the auto-temioner 1 of this embodiment, the friction forces
gencratcd between the friction members 7 and the outer cylindrical portion 2 1 of the
stationary member 20 can be made a d2fference between the cases where the tension :of the
belt iu increased and decreased.
roo381
Since the auto-tensionei; 1 ofthis embodiment is installed so that the axial
5 direction thereof is. substantidly in a horizontal .direction, muddy water, .en@ne oil and ~e
like that fldw into .the water .inla 51 flow into the water passage 52 pi.bQided on &e inside
in iht: mc$~l direction af the water idet:.5i:m, ovedownward &ng ~e peripheral direction
in the w.jter piissage 52, mid thereafter are discharged to the outside fiom.thc drai.mg@.port
52. Ther~fo.r.em, uddy water and the like can be smoothly discharged while suppresiry;,
1 5 the infi1trati.m af the muddy water and ihe'likei nto the inside .ofthk.iuto-tensi'onk1r.. A$.
a..~esuIgt~,,c elerationi n the .wear of the friction members 7 the muddy water &.the
like infiltrating between the friction members 7 :and the sliding object can b~prevedd,
thereby elongating the Iife-span afthe f~ctionm embers 7.
I00391
In addition, in this embodimenl, sine: the tip end porhon of the outer cylindrical
portion 3 1 is inserted inlo the water w1Iectiag groove 21b, ~e water passage 52 ha$ a U
shape. Accordingly, muddy Waiter and the like flowkg into the water inlet 5 1 flow into an
oulsidc part in the r d i d direction of the U-shaped water passage 52 and move down*.rd
dung the peripheral direction in this part. Therefore, muddy water and tlze like are less
-. ,.:.. r. likely to infiltrate inro the inside part in the radial di~ectiono f the U-shaped water passage
52. Consequently, infilmtion of muddy water and the Iike into the inside of the autotcnsioner
1 can be more reliably suppressed.
[00401
In addition, in this embodiment, since the drainage port 53 communicates with the
Z I., 10t~erp ortion of h ew ater passage 52, muddy water md the like flowing into the water
passage 52 can be reZiably discharged from the drainage port 53.
yo04 11
In addition, in this embodiment, in the peripheral direction range L of the drainage
port 53, the fiction members 7 are not present inside the outer cylindrical portion 21 of the
: stationary member 20. Thmefore, even when muddy water and the Iike are splashed by
the wheel axles from the lower portion of the vehicle, stick to the drainage port 53 and
infiltrate into the inside, since the friction members are not present at &e positions that are
most affected by the muddy water and the like i~lttatingfr om the drainage port 53, wear
of the friction members 7 can bc suppressed.
100423
In addition, in this ~rnbodirnents, ince the cutout 21 c that forms the drainage port
53 is provided in the stationary member 20, the position of tke drainage port 53 is constant
regardless of tl.e rotation of the rotatabIe member 30.
roo431
In addition, in this embodiment, since the dep.th direction of the water collecting
groove 2 1 b is in the axial directioq cumpared to a case where the depth direction is in ttnc
radial direction, a reduction in the strength ofthe stationary member 20 due to the water
5 cal tecting groove being provided can be suppressed,
[0044]
Incidentally, the auto-tensioner 1 of this embodiment can be put into practice in
the foI1owing modifications.
[0045]
1 rj In this embodiment, dl of the plurality of fiction members 7 are arrangd outside
the peripheral direction range L of the drainage port 53. However, any of the plurality of
friction members 7 may dso be disposed inside the peripheral direction range L of the
drainage port 53.
100461
1 ;
L -J 'l'hc leaf spring 6 and the friction membws 7 for damping the oscillation of the
rotatable member 30 may not be provided. In addition, the friction members 7 do not
need to be provided plumIly but may also be one.
100471
In this embodiment, the number of drainage ports 53 is one but may also be PI&.
... 1 ; 'fia~is , the number of cutouts 21 c formed in the peripheral wall of the water collecting
groove 21 b on the outside in the radial direction may also be plural.
1004 81
In the above embodiment, among the cuter peripheral surface of rhe outer
cylindrical partion 21 of the swtionaq member 20, the part facing the inner peripheral
L. ' I surface of the outer cylindrical portion 3 1 of the rotatable memkr 30 has a flat shape (the
diameter thereof is constant), but the embodiment is not limited to this configuration. For
example, as in an outer cylindrical portion 221 ofthe stationary member ilIusmted in Fig.
6. a groove 22 1 d may also be formed in the peripheral wall of a water collecting groove
221b an the inside in the radial direction. The g~oove2 21d may be formed aver the entire
$ 1 ) region in the peripheraI direction of the water collecting groove 22 1 b or may also be
hmed only in a part of the peripheral direction range of the water collecting groove 221 b-
R y providing the groove 22 1 d, a larger amount of water can be collected by the water
passage 252, and thus infiltration of water into the inside of the auto-tensioner can be
fiuther suppre w cd.
[0045)]
In this embodiment, the tip end portion ofthe outer cylindrical portion 3 1 of-the
rrrt;n~&le1 nember.30:i si nserted into the inside of the water collecfhg'gro'dVe2 1.bf ormed
in the outer cy 1 indfiqal postion 2 1 .of the statimary m6mbber.20. Huwevm, for. examplei :as
iIlustrated in Fig. 7, the tip end portion of an outer cylindrical porti~n3 3 1 of the rotatable
mcmber may not be inserted into the inside of a wata collecting groove 32 1 b fomd in an
uater cylindrical ponion 32 1 of the stationary member.
In the case of this rnodifimtion exampIe, similarly ta this embodiment, a chinage
Z porE 353 is configured by a curout 321c formed in the peripheral wall of the warn
collecting groove 321 b on the outside in the radial direction
[OOSO]
In this embodiment, the water collecting graove 21 b is formed so that the depth
direction thereof is in the axial direction. However, fir example, as illm~atedin Fig. 8, a
I water coI lecting grwve 42 1 b may also be formed so that ths depth direction thereof is in
thc radial direction.
In the case of this modification example, a drainage port 453 is configured by the
gap between a cutout 43 1 a formed in the fip end portion of an outer cylindrical portion 431
of the ~otatablem ember and an outer cylindrical portion 421 of the stationary member.
. .
L : [on3 r 1

Next, an auto-tensioner 501 according to a second embodiment of the present
invention will be described. He*, those having the same configurations as in the first
embodiment are denoted by the same reference numerals, and description therebf will be
. appropriately omitted.
loo521
As illustrated in Fig. 9 and Fig. 10, the auto-tensioner 50 1 of this embodiment
includes a stationary member 520, a rotatable member 530, a coil spring 4, a drainage
mechanism 5 50, a leaf spring (elastic body) 6, and a plurality af friction membm 7.
1: Incidentally, in Fig. 1 0, illustration of an outer cylindrical portion 52 1 of the shtionw
member 520 is omitred.
[(I0531
The stationary member 520 ii constituted by the outer cylindrical pohon (first
cylindrical portion) 52 1, an h e r cylindrical portion 522, and a bottom wall portion 523.
- . , ?'he inner cyIindrica1 portion 522 is f ~ e dm otatably relative to a shaft 8. ?'he inaer
cylindrical portion 522 is formed in a spiral shape so that a surface thereof facing the coil
spring 4 in the axial direction is dong the coil spring 4. Therefore, as illustrated in Fig.
10. a stepped portion 522a is formed at the boundary of the start position and the end
position of the spiral.
[0054]
Thc rotatiible member 530 is constituted by an outer cylindrical portion (second
cy lindricd portion) 53 1, an inner cylindrical portion 532, a bottom wall poflion 5 3 3, and a
pulley support portion 534. The pulley support portion 534 is formed in the same manner
as that of fhe pulley support portion 34 of the frrst embodiment. The inner cylindrical
portion 532 is mounted totatably relative to thc shaft 8 via bushes 9.
[ooss]
The outside diameter of fhe mar cylindrical portion 53 I on the base partion side
5 is larger than that on the tip end side. The part having a larger outside diameter is referred
to as a large-dbeter portion 53 la. Xn tbe outer peripheral surface (spcificslly, the
large-diameter portion 53 1 a) of the outer oylindricd portion 53 1, a water colIecting groove
53 1 b is formed over the entire periphery thereof The depth direction of the water
collecting groove 531b is in the axial direction.
, f0056J
As illustrated in Fig. 9, a cutout 531c is formed in the peripheral wdl on the outer
side in the radial direction of the water colleding groove 531b. By the cutbut 53 1c, a
drainage port 553 of the drainage mechanism 550 is canfigwed, The auto-knsioner 501
of this em bodirnent is installed so that the cutout 53 1 c (the drainage port 553) of tbe
1 i w.tatabIe member 530 is positioned on the lower side of the water coIlecting groove 53 I b.
-4 peripheral direc~ionr ange L of tbe drainage port 553 is preferabIy a range in which a
peripheral direction angle thereof is 40 degrees or less. Zmidentally, the osciliation angle
of thc rordable member 530 is in arange of 3.1 5 degrees to -15 degree.
[0057]
The tip end portion of #e outer cylindrical portion 53 Z of the rotatable member
530 is disposed to overlap the outer cyIhdrica1 poilion 521 ofthe stationary member 520
in thc radial direction. In the fust embodiment, the outer cylindri~apl ortion 3 1 of the
rotatable member 30 is disposed on the outside in the radial direction of the outer
cylindrical portion 21 of the sationary member 20. However, in this embodiment, thc
. outer cylindrical portion 52 I of the stationary member 520 is dispsed on the outside in the
radial direction of the outer cylindrical portion 531 of the rotatable member 530.
[ooss]
The tip end portion of the outer cylindrical partion 521 of the stationary member
520 is inserted into the inside of the water co1lecting groove 53 1 b formed in the outer
cylindrical portion 53 1 of the roratable member 530. Therefore, the gap between the
txJElter co I Iecting groove 5 3 3 b and the tip end portion of the outer cylindrical portion 521 of
the stationary member 520 has a U shape. The U-shaped gap forms a water Passage 552
of the drainage mechanism 550.
I00591
- . A part ob~ainedb y excluding the drainage port 553 from the gap between the outer
surface of the outer cylindrical portion 521 of the stationary member 520 and
the outer peripheral surface of tbc outer cy lindrid portion 53 Z of fie ratatable member
570 forms a water inlet 551 of the drainage mechanism 550. The drainage mechanism
550 is constitutcd by the water inlet 551, the water passage 552, and the dPaioage pee 553
described above.
[0060]
Both end portions of the coil spring 4 are respectively lacked to the stationary
:r ~~ernb5e2r0 and the rotatable member 530. As iPwtmted in Fig. 10, a mehod of locking
the end portion of coil spring 4 to the stationary member 520 is the same as the method of
locking the end portion of coil spring 4 Eo the rutatable member 30 in the first embdiment.
'rhxtt is, the left end portion 4b of the coil spring 4 in Fig. 10 is press-fitted to tfie stepped
portion S2Za of the stationary member 520 via the ldspring 6, a d accordingly, the exld
L 4 purrion 4 b of the coil spring 4 is locked to the stationaxy member 520. A method of
lacking the end portion of the coil spriag 4 to the rotatable member 530 is not
limited.
[0061]
In the first embodiment, he leaf spring 6 is disposed along the inner peripheral
1 .: surface of the outer cy Iindrical portion 21 of the stationary member 20. However, in this
embodiment, the Ieaf spring 6 is disposed dong the imer peripheral surface of the outer
cylindrical portion 531 of the ratatable member 530. In addition, one end portion of the
faaf spring 6 is bent at 90 dcgrees toward the inside in the radial direction and is nipped
between the stepped pation 522a of tbe boltom watl portion 523 of the stationary member
. j 520 and the end portion 4b of zhe coil spring 4. The other md portion af the leaf spring 6
is a free end.
100421
In the first embodiment, the ptufdity of fkiotion members 7 come into contact with
the inner peripheral surface of the outer cylindrical portion 21 of the stationwy member 20.
. 1 Iowever, in this embodiment, the plurality of friction members 7 come into contact with
the imer peripheral surface of the outer cylindrical portion 53 1 of the rotatable member
530. In addition, tbe plurality of fiction members 7 erre disposed side by side to the
peripheral direction outside a periphd direction range L of the drainage port 551. The
plurality of Friction members 7 ate preferably disposed between the outer cylkdrid
i I portion 53 1 a d the leaf spring 6 so that the pluraIity of fiction members 7 are positioned
outside a range of 20 degrees (a in Fig. 10) each is the clockwise direction and the
counrerclockwise direction from the position imrriediatdy below the central axis of
rotation when the drainage port 553 is positioned at the lowermost portion of the water
cnIlecting groove 53 1 b as illustrated in Fig. 9. A method af joining the leaf spring 6 and
the friction members 7 is the same as that in the first embadiment.
[0063]
In a case where the lension of the transmission belt is increased, the rotatable
member 530 is rotated in the counterclockwise direction of Fig. 10 agaimt the biasing
iilrcc of the coil spring 4. According to the ratntion of the outer cylindrical portion 53 I of
thc ratatable member 53 0, the friction members 7 slide on the inner peripheral surface of
the outer cylindricd p o ~ o n53 1 of the rotatable member 53 0 and the leaf spring 6 is
deformed to be sligbtl y enlarged in diameter. A[:,c0mly3 a force of the friction
-3 members 7 being pressed to the inner peripheral sdace of the outer cylindrical portion
53 1 of the ratatable member 530 is increased, and a large frictional force is generated
between the friction members 7 and the outer cylindrical portion 53 1 of the rotatable
member 53 0. The Erictional force acts as a damping force of suppressing and damping
the oscillation of the rotatable member 530.
.- . [0064]
On the other hand, in a case where the tension of the transmission belt is reduced,
the rotatable: member 530 is rotated in the clockwise direction of Fig. 1 0 by the biasing
force 6 f the coil spring 4. According to the rotation af&e outer cylindrical portion 53 1 of
the rotatable member 530, the friction members 7 slide on the h e r peripheral surface of
1 5 the outer cylindrical portion 53 1 of the rotatable member 530 4 the leaf spring 6 is
deformed to be slimy contracted in diameter. Therefore, a force of the fiction rnembers
7 being pressed to the inner peripheral surface of the outer cylindrical portion 531 of the
rotatable member 530 is decreased, and only a small frictiond force is generated between
tht friction members 7 and the outer cylindrical portion 53 1 of the rotatable member 530.
.. 1: Accordingly, the friction forces generated between the friction members 7 and the outer
cylindrical portion 53 1 of the rotatable member 530 can be made a difference betwen the
cascs where the tension of the belt is inmeased and decreased.
[0065]
In addition, in the auto-tensioner 501 of this embodiment, muddy water and the
, like flawing into the water inlet 551 flow into the water passage 552, move downward
dong the peripheral direction in the water passage 552, and thereafter, d i ~ b g etdo
the outside from the drainage port 553. Therefore, the collected muddy water and the like
can bc smoothly discharged while suppressing the infiltration of the muddy water and the
like intu the inside of the auto-tensioner 501.
[Of3661
In addition, in this embodiment, since the water passage 552 has a U shapq
similarly w the first embodiment, the id1tration of muddy water and the like into the
inside of the auto-tensioner 50 1 can be more reliably suppressed.
[0067]
In addition, in this embodiment, since the d r w e port 553 communicfttcs with
the lower portion of the water passage 552, muddy water and the like flowing into the
water passage 5 52 can be reliably discharged hm &e W a g e port 553.
100681
In addition, in this embodiment, in the peripheral direction mge L of the drainage
pon.553, the friction members 7 are not present inside the outer cylindricd portion 53 1 of
the rotatable member 53 0. Therefore, even when muddy water and the like iditrate into
the inside fiom the drainage part 553, since tkte friction members are not present at the
5 positions that are mast aected by the muddy water and the like infilm& h m the
drainage part 553, wear of the fiction members 7 can be suppressed.
100691
In addjtion, the auto-~nsione5r 01 aft his embodiment can be put into practice in
the same modifications as in the modiiication examples of the firs$ embodiment described
:. r-1 above.
[0070]
Whilc the preen1 invention has been described in detail and with reference to
specific embodim enb thereof, it wiIl be apparent to One skilled in the art that various
changes and modifications can be made therein without departing from the spirit md scope
thereof-.
The present application is based on Japanese Patent Application No. 20 1 1-1 00826,
filed on Apri 1 28,20 1 1, and Japanese Patent Application No. 20 1 2-52991, filed on March
9.2012, the entirety of which is invoked herein by reference.
. DESCRIPTION OF REFERENCE NUMERALS aPFD SIGNS
1007 I
1.501: auto-tensioner
3: coil spring
6: leaf spring (elastic body)
; i, 7: friction member
20,520: stationmy member
2 1,22 1,32 2,42 1,521 : outer cylindricill portion (fintst cylindrical portion)
2lb. 221b, 321b,42Ib, 531b: watercallectinggroove
30. 530: rotatable member
7 1.33 1.43 1.53 1 : outer cylindrical portion (second cylindrical portion)
50.550: drainage mechanism
5 1, 55 1 : water idet
52,252,552: water passage
53. 353.453,553: drainage port
CLAIMS
1 . An auto-tensioner comprising:
a starianary member having a fm cylincjsical portion;
L
J a rotatable member which has a second cylindrical portion of which at Imt a part
is dispo~dto overlap the first cylindrical portion in a radial direction, and is supported
rotatably relative to the stationary member;
a coil spring which is accuwnodated on insides of the first cylindrical partian and
the second cylindrical portion and has one end Iocked to the stationary member and the
'I other end Iocked to the rotatable member; a d
a drainage mechanism, provided at a boundary part of the first cylindricd portion
and the second cylindrical portion,
wherein the drainage mechanism comprises
a water inlet configured by a gap between an mer peripheral surface of the first
I . cy lindricd portion and an outer peripheral surface of the second cylindrical podon md
being open along a peripheral direction,
a water passage which is c o w r e d by a gap between a water collecting groove
formed along the peripheral direction itll the outer peripberal surface of one of the two
cylindrical portions and the other cy1indrica.J porlion, and communicates with the water
4. ...,. inlet, and
at least one drainage port formed in 8 peripheral wall on an outside in the radial
direction of We water passage.
2. *Ihe awe-tenstoner amarding to claim 1,
., 7
,- , wherein the water c o l l ~ ~gnogo w has a depth direction in a cylinder axi.d
riirtict,ir jn of the ~yIn&calp ortion, and
the cy Iindrical portion of the two cyIindrioal po~onsi,n which .now strr
rn1l.cctifi.gg roove is formed, h~ a tip end porti~nin serted into the water collecting groove.
+ . 3. The auto-tensioner according to claim 1 or 2, -ex comprising:
an elastic body which has one end Iocked to one member of the rotatable member
and he stacio~larym ember and the other end that is a free end, and extends along an inner
peripheral surface of the oylirldrical portion ofthe other member of the rotatable member
and the stationary member; and
a friction member which is joined immovable relative to the elastic body in the
peripheral direction and comes into contact with inner peripheral surface of the
cylindrical portion of the other member of tbe rotatable member and the stationaty
rnernber.
4. Z'he auto-tensioner accarding'to any one of cEdms 1 to 3,
wherein the drainage port communicates with a lower portion of the water
passage.
5. The auto-tensioner .according to. claim 3,
wherein the drainage port is formed. in the cylindrical portion of the oth& member,
as?
the friction membet is;not present on an.inside.d f the cylindiical portion .oft he
i. ' j othcr member'in a periphed di.recti.pn mge ofthe drainage port.