U.S. patent application number 11/295550 was filed with the patent office on 2006-09-07 for overflow tube.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Hiromichi Kimura, Daisuke Kusamoto, Terufumi Miyazaki, Kazuaki Nakamura, Kazuyuki Watanabe.
Application Number | 20060196575 11/295550 |
Document ID | / |
Family ID | 36914871 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060196575 |
Kind Code |
A1 |
Nakamura; Kazuaki ; et
al. |
September 7, 2006 |
Overflow tube
Abstract
An overflow tube is provided at an oil pan and when the oil pan
receives an amount of a working fluid exceeding a prescribed amount
the overflow tube causes the fluid to overflow to allow the fluid
to have a level set at a prescribed level. The overflow tube has an
end portion positioned in the oil pan and defining an opening of a
drain hole receiving and passing the fluid overflowing. The end
portion has a curved surface facing vertically upward and extending
to surround the opening of the drain hole, and curving in a
direction in contact with a generally horizontal direction. The
overflow tube can thus help to set the fluid's level at a
prescribed level precisely.
Inventors: |
Nakamura; Kazuaki;
(Toyota-shi, JP) ; Kimura; Hiromichi;
(Okazaki-shi, JP) ; Watanabe; Kazuyuki; (Anjo-shi,
JP) ; Miyazaki; Terufumi; (Toyota-shi, JP) ;
Kusamoto; Daisuke; (Nagoya-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi
JP
|
Family ID: |
36914871 |
Appl. No.: |
11/295550 |
Filed: |
December 7, 2005 |
Current U.S.
Class: |
141/198 |
Current CPC
Class: |
F16H 57/0408 20130101;
F16H 57/0449 20130101; F16H 57/0452 20130101 |
Class at
Publication: |
141/198 |
International
Class: |
B65B 57/06 20060101
B65B057/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2005 |
JP |
2005-062770 |
Claims
1. An overflow tube provided at a case body and causing an amount
of a working fluid exceeding a prescribed amount received by said
case body to overflow to set a level of said working fluid at a
prescribed level, the overflow tube comprising an end portion
positioned in said case body and defining an opening receiving and
passing said working fluid overflowing, said end portion having a
curved surface facing vertically upward and extending to surround
said opening, and curving in a direction in contact with a
generally horizontal direction.
2. An overflow tube provided at a case body and causing an amount
of a working fluid exceeding a prescribed amount received by said
case body to overflow to set a level of said working fluid at a
prescribed level, the overflow tube comprising an end portion
positioned in said case body and defining an opening receiving and
passing said working fluid overflowing, said end portion having an
inclined surface facing vertically upward and extending to surround
said opening, and inclining from a circumference of said end
portion toward said opening vertically downward.
3. An overflow tube provided at a case body and causing an amount
of a working fluid exceeding a prescribed amount received by said
case body to overflow to set a level of said working fluid at a
prescribed level, the overflow tube comprising an end portion
positioned in said case body and defining an opening receiving and
passing said working fluid overflowing, said end portion having a
surface facing vertically upward and extending to surround said
opening, and formed to be uneven.
4. The overflow tube according to claim 3, wherein said surface is
satin finished.
5. The overflow tube according to claim 3, wherein said surface is
serrated to have a plurality of teeth arranged along a
circumference of said opening.
6. The overflow tube according to claim 3, wherein said surface has
a groove extending from a circumference of said end portion toward
said opening.
7. An overflow tube provided at a case body and causing an amount
of a working fluid exceeding a prescribed amount received by said
case body to overflow to set a level of said working fluid at a
prescribed level, the overflow tube comprising: an end portion
positioned in said case body and defining an opening receiving and
passing said working fluid overflowing; and a guiding member
provided at said end portion in a form of a string extending from a
circumference of said end portion toward said opening.
8. An overflow tube provided at a case body and causing an amount
of a working fluid exceeding a prescribed amount received by said
case body to overflow to set a level of said working fluid at a
prescribed level, the overflow tube comprising an end portion
positioned in said case body and defining an opening receiving and
passing said working fluid overflowing, said end portion having a
surface facing vertically upward and extending to surround said
opening, and lipophilically coated.
Description
[0001] This nonprovisional application is based on Japanese Patent
Application No. 2005-062770 filed with the Japan Patent Office on
Mar. 7, 2005, the entire content of which is hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to overflow tubes
and particularly to overflow tubes used to control oil level oil in
a casing.
[0004] 2. Description of the Background Art
[0005] For a conventional oil level control scheme, for example
Japanese Patent Laying-open No. 10-213210 discloses an automatic
transmission intended to provide increased workability in storing a
prescribed amount of working fluid. The disclosed automatic
transmission is provided with an oil introduction port for
introducing the working fluid into an oil chamber and an oil
adjustment port allowing the working fluid to overflow from the oil
chamber. Thus the working fluid can be replenished while the
working fluid can overflow allowing one to confirm that the
prescribed amount of the working fluid has been stored.
[0006] Furthermore Japanese Utility Model Laying-open No. 05-017336
discloses an oil supply tank for a petroleum combustion instrument
that can help to break fuel's surface tension to prevent the fuel
from being replenished in a large amount at a time. The disclosed
tank has a plurality of recesses in a surface thereof located at a
topmost end of the tank and defining a fixed oil level in contact
with an oil level. The surface faces a vertically downward
direction.
[0007] As disclosed in Japanese Patent Laying-open No. 10-213210,
when more than the prescribed mount of oil is introduced the oil
level control scheme that exploits overflow externally discharges
the oil through an overflow tube to set an oil level at the
position of an end of the tube.
[0008] However, oil has surface tension and in reality the oil
level is set at a level several millimeters higher than the end of
the tube. The oil level thus set is unstable because of a condition
in introducing the oil, the oil's waving, and the like, and may
have an error introduced therein. Furthermore, it also causes the
tube to have difficulty in stopping the oil flowing out the tube
and one cannot determine when to apply a drain plug to close the
tube, resulting in poor workability in exchanging the oil.
SUMMARY OF THE INVENTION
[0009] The present invention has been made to overcome the above
disadvantage, and it contemplates an overflow tube that can help to
set an oil level precisely at a prescribed level.
[0010] The present invention in one aspect provides an overflow
tube provided at a case body and causing an amount of a working
fluid exceeding a prescribed amount received by the case body to
overflow to set a level of the working fluid at a prescribed level.
The overflow tube includes an end portion positioned in the case
body and defining an opening receiving and passing the working
fluid overflowing. The end portion has a curved surface facing
vertically upward and extending to surround the opening, and
curving in a direction in contact with a generally horizontal
direction. It should be noted that "facing vertically upward" means
facing away from the ground with respect to the horizon (or a
straight line perpendicular to a vertical direction) and
corresponds to a range from a vertically upward direction to a
horizontal direction.
[0011] The overflow tube thus structured has the curved surface
curved in a direction that is in contact with a generally
horizontal direction. The working fluid having a level raised
around the end portion by surface tension can be guided along the
curved surface into the opening. Thus the working fluid's surface
tension can be broken and the working fluid can have a level
readily set at a prescribed level as intended.
[0012] The present invention in another aspect provides an overflow
tube provided at a case body and causing an amount of a working
fluid exceeding a prescribed amount received by the case body to
overflow to set a level of the working fluid at a prescribed level.
The overflow tube includes an end portion positioned in the case
body and defining an opening receiving and passing the working
fluid overflowing. The end portion has an inclined surface facing
vertically upward and extending to surround the opening, and
inclining from a circumference of the end portion toward the
opening vertically downward.
[0013] The overflow tube thus structured has the inclined surface
inclined from the end portion, which is filled with the working
fluid, toward the opening vertically downward. The working fluid
having a level raised around the end portion by surface tension can
be guided along the inclined surface into the opening. Thus the
working fluid's surface tension can be broken and the working fluid
can have a level readily set at a prescribed level as intended.
[0014] The present invention in still another aspect provides an
overflow tube provided at a case body and causing an amount of a
working fluid exceeding a prescribed amount received by the case
body to overflow to set a level of the working fluid at a
prescribed level. The overflow tube includes an end portion
positioned in the case body and defining an opening receiving and
passing the working fluid overflowing. The end portion has a
surface facing vertically upward and extending to surround the
opening, and formed to be uneven.
[0015] The overflow tube that has the end portion with an uneven
surface can contact the working fluid over a surface having an
increased area. This can promote a fluid guiding effect attributed
to capillarity (i.e., the action by which the surface of a liquid
where it is in contact with a solid is attracted to the solid) to
more positively guide to the opening the working fluid contacting
the surface. Thus the working fluid's surface tension can be broken
and the working fluid can have a level readily set at a prescribed
level as intended.
[0016] Preferably the surface is satin finished. Furthermore,
preferably the surface is serrated to have a plurality of teeth
arranged along a circumference of the opening. Furthermore,
preferably the surface has a groove extending from a circumference
of the end portion toward the opening. The overflow tube thus
structured allows a capillary fluid guiding effect to more
effectively be utilized.
[0017] The present invention in still another aspect provides an
overflow tube provided at a case body and causing an amount of a
working fluid exceeding a prescribed amount received by the case
body to overflow to set a level of the working fluid at a
prescribed level. The overflow tube includes: an end portion
positioned in the case body and defining an opening receiving and
passing the working fluid overflowing; and a guiding member
provided at the end portion in a form of a string extending from a
circumference of the end portion toward the opening.
[0018] The overflow tube thus structured allows the working fluid
having a level raised around the end portion by surface tension to
be guided through capillarity along the guide member into the
opening. Thus the working fluid's surface tension can be broken and
the working fluid can have a level readily set at a prescribed
level as intended.
[0019] The present invention in still another aspect provides an
overflow tube provided at a case body and causing an amount of a
working fluid exceeding a prescribed amount received by the case
body to overflow to set a level of the working fluid at a
prescribed level. The overflow tube includes an end portion
positioned in the case body and defining an opening receiving and
passing the working fluid overflowing. The end portion has a
surface facing vertically upward and extending to surround the
opening, and lipophilically coated.
[0020] The overflow tube that has the end portion with a surface
coated with a lipophilic coating allows the working fluid to have a
surface contacting that of the end portion at a reduced contact
angle. Thus the working fluid's surface tension can be broken and
the working fluid can have a level readily set at a prescribed
level as intended. Note that the "contact angle" as referred to
herein indicates an angle formed by a surface of a solid contacting
a liquid and a gas and a surface of the liquid at a boundary
interface at which the three phases contact each other, as
represented on the liquid's side.
[0021] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is an exploded view of an automatic transmission
employing the present overflow tube in a first embodiment.
[0023] FIG. 2 is a cross section of the automatic transmission of
FIG. 1, as enlarged at a portion encircled by a chained line
II.
[0024] FIG. 3 is a top view of the overflow tube as seen in a
direction indicated in FIG. 2 by an arrow III.
[0025] FIG. 4 is a cross section for illustrating an oil level set
by the overflow tube of FIG. 2.
[0026] FIG. 5 is a cross section of the overflow tube of FIG. 2 in
an exemplary variation.
[0027] FIGS. 6 and 7 are cross sections of the present overflow
tube in second and third embodiments, respectively.
[0028] FIG. 8 is a cross section of the overflow tube of FIG. 7 in
a first exemplary variation.
[0029] FIGS. 9A and 9B are a perspective view and a cross section,
respectively, of the overflow tube of FIG. 7 in a second exemplary
variation.
[0030] FIGS. 10A and 10B are a perspective view and a cross
section, respectively, of the present overflow tube in a fourth
embodiment.
[0031] FIG. 11 is a perspective view of the present overflow tube
in a fifth embodiment.
[0032] FIG. 12 is a cross section of the overflow tube of FIG. 11
at a portion encircled by a chained line XII indicated in FIG.
11.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] The present invention in embodiments will now be described
with reference to the drawings. In the figures, identical or like
components are identically denoted.
First Embodiment
[0034] With reference to FIG. 1 an automatic transmission 10 has a
casing formed of a transmission case 11 opened in a vertically
downward direction and an oil pan 12 in the form of a saucer
attached to transmission case 11 to close the position of the
opening. In transmission case 11 is housed a gear, a shaft, a
bearing and the like shifting force output from an engine for
output toward a drive shaft.
[0035] The casing of automatic transmission 10 has a prescribed
amount of working fluid sealed therein and oil pan 12 receives the
working fluid. The working fluid serves for example as a lubricant
oil referred to as automatic transmission fluid (ATF) and serving
to allow a shifting clutch to be operated and a torque converter's
force to be transmitted, and prevent gears and other similar
mechanical elements from seizing up. Oil pan 12 has a bottom 12m
having a mechanism located at a position indicated in a circle II
for controlling the working fluid in level.
[0036] With reference to FIGS. 1 and 2, oil pan 12 is provided at
bottom 12m with an overflow tube 21 having a cylindrical portion 26
extending from bottom 12m vertically upward toward an internal
space 13 of oil pan 12, and an end portion 23 formed at an end of
cylindrical portion 26 opposite to bottom 12m.
[0037] Cylindrical portion 26 has external and internal walls 28
and 27, respectively, and is formed to extend cylindrically around
a vertically extending center axis 101. Surrounded by internal wall
22 is a drain hole 22 communicating external to oil pan 12. Note
that overflow tube 21 may be integrated with oil pan 12 or attached
to a side portion of oil pan 12. Furthermore oil pan 12 may not
necessarily be provided at oil pan 12. For example it may be
provided at transmission case 11. Furthermore, cylindrical portion
26 may by bent between bottom 12m and end portion 23.
[0038] With reference to FIGS. 1-3, end portion 23 is formed to
flare from cylindrical portion 26. At a location surrounded by end
portion 23 is defined an opening of drain hole 22, and at that
location drain hole 22 communicates with internal space 13. End
portion 23 is formed in a body of revolution around center axis
101. More specifically, end portion 23 has an identical cross
section in a circumferential direction with center axis 101 serving
as a center. Working fluid 31 contacts external wall 28 and fills a
circumference of end portion 23 (i.e., a side opposite drain hole
22 with end portion 23 posed therebetween).
[0039] End portion 23 has a curved surface 23a. Curved surface 23a
faces vertically upward and extends annularly to surround the
opening of drain hole 22. Curved surface 23a is formed to curve to
contact in a generally horizontal direction. Curved surface 23a is
formed to directly adjacent to internal wall 27. Curved surface 23a
has a portion 23q extending from a portion 23p, which is in contact
with a generally horizontal direction, toward internal wall 27 in a
direction varying from the generally horizontal direction to a
vertically downward direction.
[0040] FIG. 4 illustrates an oil level set by the overflow tube of
FIG. 2. More specifically, FIG. 4 shows a portion indicated in FIG.
2 that is surrounded by a chained circle IV. With reference to
FIGS. 1-4, working fluid 31 is introduced into the casing of
automatic transmission 10 through a port (not shown) formed through
transmission case 11. When working fluid 31 introduced exceeds a
prescribed amount the excessive amount of working fluid 31 is
externally discharged through the overflow tube 21 drain hole
22.
[0041] In doing so, surface tension acts to causes working fluid 31
to have a level, higher than the position of the opening of
overflow tube 21. In the present embodiment, however, curved
surface 23a is provided at a position spacing working fluid 31 and
drain hole 22. As such, working fluid 31 having a level raised by
surface tension is guided along the curved surface 23a portion 23q
toward drain hole 22. Working fluid 31 can thus have a raised level
31a' reduced to a level 31a having substantially the same level as
portion 23p of curved surface 23a, and set at that level.
Furthermore working fluid 31 located at the raised level will not
gradually flow out drain hole 22, and the tube can thus have
reduced difficulty in stopping working fluid 31 discharged
therethrough. This can provide increased workability in controlling
the level.
[0042] With reference to FIG. 2, to further reduce difficulty in
stopping working fluid 31 discharged through drain hole 22,
overflow tube 21 may have internal wall 27 with a groove formed
therein along center axis 101. The working fluid can flow along the
groove and thus be externally discharged through drain hole 22
rapidly. Note that the embodiments described hereinafter can all
have internal wall 27 provided with a groove.
[0043] Once a level has completely been set an oil plug (not shown)
is attached to overflow tube 21 to close drain hole 22.
[0044] In the present invention as described in the first
embodiment overflow tube 21 is provided at oil pan 12 serving as a
case body and when oil pan 12 receives more than a prescribed
amount of working fluid 31 overflow tube 21 causes the excessive
amount of working fluid 31 to overflow to set level 3la at a
prescribed level. Overflow tube 21 has end portion 23 positioned
internal to oil pan 12 and defining an opening of drain hole 22
serving as an opening receiving and passing the working fluid that
overflows. End portion 23 has curved surface 23a facing vertically
upward and extending to surround the opening of drain hole 22, and
also curving in a direction contacting a generally horizontal
direction.
[0045] The present overflow tube 21 in the first embodiment thus
configured allows end portion 23 that has curved surface 23 to
break surface tension. As such, when automatic transmission 10 is
assembled or repaired or working fluid 31 is exchanged or the like,
working fluid 31 can have level 31a readily set at a prescribed
level previously assumed within oil pan 12. This can for example
prevent level 31a from attaining too high a level resulting in
increased agitation resistance between a gear housed in
transmission case 11 and working fluid 31. This can contribute to
reduced energy loss in automatic transmission 10 and also prevent
the working fluid from increasing in temperature and thus
degrading. Furthermore, level 31a will not be too low, and a pump
that sucks working fluid 31 from oil pan 12 will not suck air.
Automatic transmission 10 can thus be enhanced in reliability and
durability.
[0046] Furthermore, as an appropriate amount of working fluid 31
can be supplied to oil pan 12, working fluid 31 is not wastefully
consumed, which can contribute to reduced cost. Furthermore
automatic transmission 10 can be prevented from having a weight
larger than assumed.
[0047] With reference to FIG. 5, an overflow tube 41 presented as
an exemplary variation has cylindrical portion 26 and an end
portion 42 formed at an end of cylindrical portion 26. End portion
42 is directly adjacent to cylindrical portion 26 and extends
therefrom along center axis 101 cylindrically. End portion 42 has a
curved surface 42a located at its extending end. Curved surface 42a
faces vertically upward and extends to surround the opening of
drain hole 22 and curves in a direction contacting a generally
horizontal direction. Overflow tube 41 thus configured can be as
effective as overflow tube 21.
[0048] Note that while in the present embodiment overflow tube 21
is applied to automatic transmission 10, it is also applicable to a
manual transmission, a continuously variable transmission (CTV),
and the like. Furthermore the present invention is similarly
applicable to engines, power shovels, working robots and other wet
sump machines that require controlling a fluid in amount and
level.
Second Embodiment
[0049] In the present embodiment the arrangement that overlaps that
of overflow tube 21 in the first embodiment will not be described
repeatedly.
[0050] With reference to FIG. 6 an overflow tube 46 has cylindrical
portion 26 and an end portion 47 formed at an end of cylindrical
portion 26. End portion 47 is directly adjacent to cylindrical
portion 26 and extends therefrom along center axis 101
cylindrically. End portion 47 has an inclined surface 47a located
at its extending end. Inclined surface 47a faces vertically upward
and extends annularly to surround the opening of drain hole 22.
[0051] Inclined surface 47a has an outer circumferential edge 47p
directly adjacent to external wall 28 and located relatively
distant from center axis 101 and an inner circumferential edge 47q
directly adjacent to internal wall 27 and located relatively close
to center axis 101. Inclined surface 47a as seen from outer
circumferential edge 47p toward inner circumferential edge 47q is
formed to extend vertically downward. Inclined surface 47a may be
adapted to have an inclination varying between outer
circumferential edge 47p and inner circumferential edge 47q.
[0052] Thus working fluid 31 having a level raised around overflow
tube 46 by surface tension is guided along inclined surface 47a
into drain hole 22. Working fluid 31 can thus have level 31a set
substantially at the same level as outer circumferential edge 47p
of inclined surface 47a.
[0053] The present invention in the second embodiment provides
overflow tube 46 including an end portion 47 positioned internal to
oil pan 12 and defining an opening of drain hole 22 receiving and
passing a working fluid that overflows. End portion 47 has an
inclined surface 47a facing vertically upward and extending to
surround the opening of drain hole 22, and also inclining from a
circumference of end portion 47 toward the opening of drain hole 22
vertically downward.
[0054] Overflow tube 46 thus configured can achieve an effect
similar to that described in the first embodiment.
Third Embodiment
[0055] In the present embodiment the arrangement that overlaps that
of overflow tube 21 in the first embodiment will not be described
repeatedly.
[0056] With reference to FIG. 7 an overflow tube 51 has cylindrical
portion 26 and an end portion 52 formed at an end of cylindrical
portion 26. End portion 52 is directly adjacent to cylindrical
portion 26 and extends therefrom along center axis 101
cylindrically. End portion 52 has an uneven surface 52a located at
its extending end. Uneven surface 52a faces vertically upward and
extends annularly to surround the opening of drain hole 22.
[0057] Uneven surface 52a is formed of surfaces of a protrusion 53
and a depression 54, respectively, alternately arranged around
center axis 101 circumferentially. Protrusion 53 and depression 54
are formed to have a top surface 53a and a bottom surface 54a,
respectively, having a step in a direction along center axis 101.
Depression 54 is formed to extend around center axis 101
radially.
[0058] Uneven surface 52 thus formed enables working fluid 31
filling around the opening of drain hole 22 to contact surface 52a
over an area larger than when surface 52a is formed flat. This can
promote a capillary fluid guiding effect to guide working fluid 31
into drain hole 22 more positively. Working fluid 31 can thus have
level 31a set substantially at the same level of top surface 53a of
protrusion 53. It should be noted that for a different height of
protrusion 53, a different width of depression 54 and some other
conditions, level 31a may be set at bottom surface 54a of
depression 54.
[0059] The present invention in the third embodiment provides
overflow tube 51 including an end portion 52 positioned internal to
oil pan 12 and defining an opening of drain hole 22 receiving and
passing a working fluid that overflows. End portion 52 has an
uneven surface 52a facing vertically upward and extending to
surround the opening of drain hole 22.
[0060] Overflow tube 51 thus configured can achieve an effect
similar to that described in the first embodiment.
[0061] With reference to FIG. 8, an overflow tube 56 as an
exemplary variation has cylindrical portion 26 and an end portion
57 formed at an end of cylindrical portion 26. End portion 57 has a
serrated surface 57a facing vertically upward and, as seen at a
circumference of end portion 57, zigzagging around center axis 101
circumferentially. This arrangement allows working fluid 31 to have
level 31a set substantially at the same level as an apex of
serrated surface 57a. An effect similar to that of overflow tube 51
can be achieved.
[0062] FIG. 9 shows the overflow tube of FIG. 7 in a second
exemplary variation, or an overflow tube 61, having cylindrical
portion 26 and an end portion 62 formed at an end of cylindrical
portion 26 and having an uneven surface 62a formed of a surface of
a protrusion 63 provided around center axis 101 for every
90.degree. and a surface of a groove 64 formed between adjacent
protrusions 63. Protrusion 63 and groove 64 are formed to have a
top surface 63a and a bottom surface 64a, respectively, together
forming a step in a direction along center axis 101, with top
surface 63a smaller in area than bottom surface 64a. This
arrangement allows working fluid 31 to have level 31a set
substantially at the same level as bottom surface 64a of groove 64.
An effect similar to that of overflow tube 51 can be achieved.
[0063] Furthermore, as a still another exemplary variation, the end
portion may have an end surface satin finished and thus uneven. In
that case, the end portion preferably has the end surface with
maximum and minimum heights having a difference of 0.1 mm or
larger, more preferably 0.3 mm or larger, most preferably 0.5 mm or
larger.
Fourth Embodiment
[0064] In the present embodiment the arrangement that overlaps that
of overflow tube 21 in the first embodiment will not be described
repeatedly.
[0065] With reference to FIG. 10, an overflow tube 66 is formed of
cylindrical portion 26, an end portion 67 formed at an end of
cylindrical portion 26, and a guiding string 68 provided at end
portion 67. End portion 67 is directly adjacent to cylindrical
portion 26 and extends therefrom along center axis 101
cylindrically. End portion 67 has an end surface 67a located at its
extending end. End surface 67a is formed in a plane extending in a
generally horizontal direction. Guiding string 68 is located on end
surface 67a and also extends from external wall 28 to internal wall
27. Note that while the figure shows only a single guiding string
68, more than one guiding string 68 may be provided.
[0066] Working fluid 31 contacting guiding string 68 around a
circumference of overflow tube 66 is drawn by capillarity to
guiding string 68 and guided along guiding string 68 into drain
hole 22. Working fluid 31 can thus have level 31a set substantially
at the same level as end surface 67a.
[0067] In the present invention as described in the fourth
embodiment overflow tube 66 includes end portion 67 positioned
internal to oil pan 12 and defining an opening of drain hole 22
receiving and passing a working fluid that overflows, and guiding
string 68 provided at end portion 67 and serving as a guiding
member in the form of a string extending from a circumference of
end portion 67 into the opening of drain hole 22.
[0068] Overflow tube 66 thus configured can achieve an effect
similar to that described in the first embodiment.
Fifth Embodiment
[0069] In the present embodiment the arrangement that overlaps that
of overflow tube 21 in the first embodiment will not be described
repeatedly.
[0070] With reference to FIGS. 11 and 12 an overflow tube 71 has
cylindrical portion 26 and an end portion 72 formed at an end of
cylindrical portion 26. End portion 72 is directly adjacent to
cylindrical portion 26 and extends therefrom along center axis 101
cylindrically. End portion 72 has an end surface 72a located at its
extending end. End surface 72a is formed in a plane extending
substantially in a generally horizontal direction. End surface 72a
is directly adjacent to both external wall 28 and internal wall 27.
End surface 72a for example has applied thereto a lipophilic
coating 73 formed of titanium oxide.
[0071] Working fluid 31 having a level raised by surface tension
around overflow tube 66 contacts a surface 73a of lipophilic
coating 73 at a reduced angle .alpha.. Working fluid 31 can thus
have a raised level 31a' reduced to level 31a located substantially
at the same level as surface 73a. Working fluid 31 can thus have a
level set at that level.
[0072] The present invention in the fifth embodiment provides
overflow tube 71 including an end portion 72 positioned internal to
oil pan 12 and defining an opening of drain hole 22 receiving and
passing a working fluid that overflows. End portion 72 has an end
surface 72a facing vertically upward and extending to surround the
opening of drain hole 22, and lipophilically coated.
[0073] Overflow tube 71 thus configured can achieve an effect
similar to that described in the first embodiment.
[0074] The overflow tubes of the first to fifth embodiments may
structurally be combined as appropriate to form a different
overflow tube. For example, overflow tube 21 of the first
embodiment may have curved surface 23a satin finished, and overflow
tube 66 of the fourth embodiment may have end surface 67a
lipophilically coated.
[0075] Thus the present invention can provide an overflow tube that
can help to set a level at a prescribed level precisely.
[0076] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the scope of the present invention being limited
only by the terms of the appended claims.
* * * * *