U.S. patent application number 11/002017 was filed with the patent office on 2005-06-09 for fluid machine.
Invention is credited to Fujii, Toshiro, Hoshino, Tatsuyuki, Ishida, Atsuhiro.
Application Number | 20050123415 11/002017 |
Document ID | / |
Family ID | 34631722 |
Filed Date | 2005-06-09 |
United States Patent
Application |
20050123415 |
Kind Code |
A1 |
Hoshino, Tatsuyuki ; et
al. |
June 9, 2005 |
Fluid machine
Abstract
A fluid machine includes a motor and a motor housing. The motor
housing defines a motor chamber for accommodating the motor. The
motor chamber is filled with inert gas. A rotor rotates in
accordance with rotation of the motor. A pump housing defines a
pump chamber for accommodating the rotor. A dividing wall is
located between the pump housing and the motor housing. The pump
housing and the motor housing are attached to each other via the
dividing wall. Therefore, water is prevented from being generated
in the motor chamber even if fluid that contains hydrogen leaks
from the pump chamber to the motor chamber.
Inventors: |
Hoshino, Tatsuyuki;
(Kariya-shi, JP) ; Fujii, Toshiro; (Kariya-shi,
JP) ; Ishida, Atsuhiro; (Kariya-shi, JP) |
Correspondence
Address: |
Morgan & Finnegan, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
34631722 |
Appl. No.: |
11/002017 |
Filed: |
December 2, 2004 |
Current U.S.
Class: |
417/369 ;
417/366; 417/410.4 |
Current CPC
Class: |
F04C 28/28 20130101;
F04C 18/16 20130101; F04C 29/0085 20130101; F04C 18/123 20130101;
F04C 18/086 20130101; F01C 21/10 20130101; F04C 27/00 20130101;
F04C 2210/224 20130101; F04C 25/00 20130101; F04C 27/009
20130101 |
Class at
Publication: |
417/369 ;
417/366; 417/410.4 |
International
Class: |
F04B 017/00; F04B
035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2003 |
JP |
2003-406052 |
Claims
1. A fluid machine, comprising: a motor; a motor housing, which
defines a motor chamber for accommodating the motor, the motor
chamber being filled with inert gas; a rotor, which rotates in
accordance with rotation of the motor; a pump housing, which
defines a pump chamber for accommodating the rotor; and a dividing
wall located between the pump housing and the motor housing, the
pump housing and the motor housing being attached to each other via
the dividing wall.
2. The fluid machine according to claim 1, wherein the inert gas is
at least one of nitrogen, argon, helium, neon, xenon, and
krypton.
3. The fluid machine according to claim 1, further comprising: a
rotary shaft, which transmits rotation of the motor to the rotor,
the dividing wall has a through hole through which the rotary shaft
extends; and a sealing material located between the inner surface
of the through hole and the rotary shaft.
4. The fluid machine according to claim 1, further comprising a
sealing member located at a contact portion between the motor
housing and the dividing wall.
5. The fluid machine according to claim 1, wherein the dividing
wall includes a plurality of dividing members, which are piled on
each other, and a sealing member is located at least one of a
portion between the adjacent dividing members, a portion between
the motor housing and the adjacent dividing member, and a portion
between the pump housing and the adjacent dividing member.
6. The fluid machine according to claim 1, wherein the motor
housing is open toward the dividing wall and the pump housing is
open toward the dividing wall, wherein the dividing wall closes the
motor housing and the pump housing.
7. The fluid machine according to claim 1, wherein the fluid
machine is a fluid pump for fluid including hydrogen.
8. The fluid machine according to claim 1, wherein the fluid
machine is incorporated in a fuel cell system.
9. A fluid machine, comprising: a motor; a motor housing, which
defines a motor chamber for accommodating the motor, the motor
chamber being filled with inert gas; a rotor, which rotates in
accordance with rotation of the motor; a pump housing, which
defines a pump chamber for accommodating the rotor; a dividing wall
located between the pump housing and the motor housing, the pump
housing and the motor housing being attached to each other via the
dividing wall, and the motor housing is open toward the dividing
wall and the pump housing is open toward the dividing wall, wherein
the dividing wall closes the motor housing and the pump housing; a
rotary shaft, which transmits rotation of the motor to the rotor,
the dividing wall has a through hole through which the rotary shaft
extends; and a sealing material located between the inner surface
of the through hole and the rotary shaft.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a fluid machine that draws
fluid into a pump chamber by rotation of a rotor and discharges the
fluid out of the pump chamber through an outlet.
[0002] In a conventional fuel cell system that generates electric
power using hydrogen gas and oxidizing gas as reactive gas, water
is produced during generation of electric power. To discharge the
generated water from the fuel cell, the hydrogen gas and the
oxidizing gas are supplied to the fuel cell by an amount greater
than a consumption amount required to generate electric power.
Therefore, the hydrogen gas discharged from the fuel cell (so
called hydrogen off-gas) includes unreacted hydrogen gas.
Discharging the unreacted hydrogen gas deteriorates fuel economy of
the fuel cell system. Therefore, the hydrogen off-gas is circulated
and returned to the fuel cell to improve the fuel economy of the
fuel cell system.
[0003] A fluid machine is used in the fuel cell system as means for
forcibly circulating the hydrogen off-gas (see Japanese Laid-Open
Patent Publication No. 2003-151592). That is, the fuel cell system
of the above publication draws the hydrogen off-gas discharged from
the fuel cell to the fluid machine via a condenser, which separates
gas from liquid. The machine draws the hydrogen off-gas into a pump
chamber and mixes the drawn hydrogen off-gas with new hydrogen gas
supplied from a hydrogen tank. The hydrogen off-gas that is mixed
with the new hydrogen gas is supplied to an anode of the fuel cell
again. The ambient air, which serves as the oxidizing gas, is
supplied to a cathode of the fuel cell via another fluid
machine.
[0004] The fluid machine having such a function has been proposed
in, for example, Japanese Laid-Open Patent Publication No.
2002-54587. The fluid machine of this Publication is an air pump
that supplies air (oxidizing gas) to a fuel cell. The pump includes
a motor housing and a pump housing, which are integrally attached
to each other. The motor housing defines a motor chamber, which
accommodates a motor. The pump housing defines a pump chamber,
which accommodates a rotor, which rotates in accordance with
rotation of the motor. The motor chamber and the pump chamber are
separated by a bottom wall (dividing wall) of the motor housing
through which a rotary shaft of the motor extends. A sealing
material is provided at a portion of the bottom wall where the
rotary shaft is inserted.
[0005] As described above, a fluid machine (hydrogen pump) for
drawing hydrogen gas (hydrogen off-gas) and supplying it to the
fuel cell is provided in the fuel cell system besides the fluid
machine (air pump) for drawing air and supplying it to the fuel
cell. In this case, the fluid machine (hydrogen pump) has
substantially the same structure as the fluid machine (air pump)
disclosed in Japanese Patent Publication No. 2002-54587 except that
the fluid to be drawn and supplied is not air but hydrogen
off-gas.
[0006] However, drawing and supplying hydrogen off-gas with the
fluid machine disclosed in Japanese Patent Publication No.
2002-54587 arises the following problems. That is, since the
hydrogen off-gas has characteristics to penetrate through metal,
the hydrogen off-gas often penetrates through the bottom wall
(dividing wall) of the motor housing, which separates the pump
chamber from the motor chamber, and enters the motor chamber.
Although a sealing material is provided at a portion of the bottom
wall of the motor housing where the rotary shaft of the motor is
inserted through, a slight gap exists to permit the rotary shaft to
rotate. Therefore hydrogen off-gas moves from the pump chamber to
the motor chamber through the slight gap.
[0007] In general, air is sealed in the motor chamber during
assembly. Therefore, the oxygen contained in the air in the motor
chamber and the hydrogen in the hydrogen off-gas that entered the
motor chamber might react and generate water in the motor chamber.
If water is generated as described above, members (such as a motor)
in the motor chamber might be corroded. As a result, the
performance of the fluid machine might deteriorate.
SUMMARY OF THE INVENTION
[0008] Accordingly, it is an objective of the present invention to
provide a fluid machine that prevents water from being generated in
a motor chamber even if fluid that contains hydrogen leaks from a
pump chamber to the motor chamber, and prevents the performance of
the fluid machine from deteriorating.
[0009] To achieve the above-mentioned objective, the present
invention provides a fluid machine. The machine includes a motor
and a motor housing. The motor housing defines a motor chamber for
accommodating the motor. The motor chamber is filled with inert
gas. A rotor rotates in accordance with rotation of the motor. A
pump housing defines a pump chamber for accommodating the rotor. A
dividing wall is located between the pump housing and the motor
housing. The pump housing and the motor housing are attached to
each other via the dividing wall.
[0010] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0012] FIG. 1 is a plan cross-sectional view illustrating a
hydrogen pump according to one embodiment of the present invention;
and
[0013] FIG. 2 is a partially enlarged view of FIG. 1 explaining the
state where hydrogen off-gas enters the motor chamber of the pump
shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] One embodiment of the present invention will now be
described with reference to FIGS. 1 and 2.
[0015] FIG. 1 shows a hydrogen pump 10, which is one type of fluid
machine used in a fuel cell system. That is, the fluid machine in
this embodiment is a fluid pump for fluid including hydrogen. The
hydrogen pump 10 of this embodiment is formed by a motor portion M
and a pump portion P. The motor portion M includes a substantially
cup-shaped motor housing 11, which has a closed first end (left end
in FIG. 1) and an open second end (right end in FIG. 1), and a
partition (dividing member) 12, which is coupled to the motor
housing 11 to close the opening. The inner surface of the motor
housing 11 and the inner surface of the partition 12 define a motor
chamber 13. The motor chamber 13 is filled with inert gas (such as
nitrogen) G.
[0016] The pump portion P includes a substantially oval cup-shaped
pump housing 14, which has an open first end (left end in FIG. 1)
and a bearing block (dividing member) 16, which is coupled to the
pump housing 14 with bolts 15 to close the opening. The inner
surface of the pump housing 14 and the inner surface of the bearing
block 16 define a pump chamber 17. In this embodiment, the
partition 12 and the bearing block 16 form a dividing wall. The
motor housing 11 is open toward the dividing wall and the pump
housing 14 is open toward the dividing wall. The dividing wall
closes the motor housing 11 and the pump housing 14.
[0017] A substantially oval cup-shaped gear housing 18 is secured
to a second end (right end in FIG. 1) of the pump housing 14 of the
pump portion P with bolts (not shown). The gear housing 18 is
smaller than the pump housing 14. The outer surface of the second
end of the pump housing 14 and the inner surface of the gear
housing 18 define a gear chamber 19. The outer surface of the
partition 12 and the outer surface of the bearing block 16 are
secured to each other with bolts (not shown) so that the motor
portion M is integrated with the pump portion P. An O-ring 20 is
arranged between the motor housing 11 and the partition 12, the
pump housing 14 and the bearing block 16, the pump housing 14 and
the gear housing 18, and the partition 12 and the bearing block 16
as a sealing member to keep the interior sealed from the
outside.
[0018] A bearing 22 is located at a bottom portion 21 of the motor
housing 11. The bearing 22 is coaxial with the motor housing 11 and
faces the interior of the motor chamber 13. The bearing 22
rotatably supports a first end (left end in FIG. 1) of a drive
shaft (rotary shaft) 23. A second end of the drive shaft 23 extends
to the interior of the gear chamber 19 through a through hole 12a
formed in the partition 12, a through hole 16a formed in the
bearing block 16, and a through hole 24a formed in a bottom portion
24 of the pump housing 14.
[0019] The second end of the drive shaft 23 is rotatably supported
by a bearing 25 located at the bottom portion 24 of the pump
housing 14, and the middle portion of the drive shaft 23 is
rotatably supported by a bearing 26 provided in the bearing block
16. A motor rotor 27 is secured to the drive shaft 23 in the motor
chamber 13. A motor stator 28 is secured to the motor housing 11
such that the motor stator 28 is located on the outer
circumferential side of the motor rotor 27. The motor rotor 27 and
the motor stator 28 form an electric motor 29.
[0020] A driven shaft 30, which is parallel to the drive shaft 23,
is located in the pump chamber 17 of the pump portion P. The ends
of the driven shaft 30 are rotatably supported by a bearing 31
provided in the bottom portion 24 of the pump housing 14 and a
bearing 32 provided in the bearing block 16. A two-blade drive
rotor 33 and a two-blade driven rotor 34 are secured to the drive
shaft 23 and the driven shaft 30 in the pump chamber 17,
respectively. A second end (right end) of the driven shaft 30
extends to the interior of the gear chamber 19 through the bottom
portion 24 of the pump housing 14 in the same manner as the second
end (right end) of the drive shaft 23. A drive gear 35 secured to
the second end of the drive shaft 23 and a driven gear 36 secured
to the second end of the driven shaft 30 engage with each other in
the gear chamber 19.
[0021] A seal ring (sealing material) 37 is located in the bearing
block 16 next to the bearing 26 on the side facing the drive rotor
33 to seal the gap between the drive shaft 23 and the bearing block
16. The seal ring 37 is located between the inner surface of the
through hole 16a and the drive shaft 23. In the same manner, a seal
ring (sealing material) 37 is located in the bearing block 16 next
to the bearing 32 on the side facing the driven rotor 34 to seal
the gap between the driven shaft 30 and the bearing block 16. In
this embodiment, a seal ring 37 is also located in the bottom
portion 24 of the pump housing 14 next to the bearing 25 on the
side facing the drive rotor 33 to seal the gap between the drive
shaft 23 and the pump housing 14. In the same manner, a seal ring
(sealing material) 37 is located in the bottom portion 24 of the
pump housing 14 next to the bearing 31 on the side facing the
driven rotor 34 to seal the gap between the driven shaft 30 and the
pump housing 14.
[0022] The hydrogen pump 10 is placed such that an imaginary plane
that includes the axes of the drive shaft 23 and the driven shaft
30 is horizontal. An inlet (not shown) is formed in the ceiling of
the pump housing 14 of the pump portion P to draw hydrogen off-gas
discharged from the fuel cell, which is not shown, into the pump
chamber 17. An outlet 38 is formed in the bottom portion of the
pump chamber 17 to discharge the hydrogen off-gas drawn by the
rotation of the rotors 33, 34 from the pump chamber 17. Therefore,
the hydrogen off-gas drawn into the pump chamber 17 from the inlet
is discharged through the outlet 38 and supplied to the fuel cell
again. As described above, the hydrogen pump 10 repeats drawing and
supplying operation in which hydrogen off-gas is drawn into the
pump chamber 17 and then discharged.
[0023] The operation of the hydrogen pump (fluid machine) 10
constituted as described above will now be described. The operation
performed when hydrogen off-gas in the pump chamber 17 enters the
motor chamber 13 will mainly be discussed below.
[0024] In a case where the hydrogen pump 10 repeats the drawing and
supplying operation of hydrogen off-gas as described above, part of
the hydrogen off-gas drawn into the pump chamber 17 from the inlet
might enter the motor chamber 13 via the through hole 16a of the
bearing block 16 and the through hole 12a of the partition 12 as
shown in FIG. 2. That is, although the seal ring 37 is located in
the through hole 16a of the bearing block 16, a slight gap is
formed between the seal ring 37 and the drive shaft 23 to permit
the drive shaft 23 to rotate.
[0025] A gap is also formed between the through hole 12a of the
partition 12 and the circumferential surface of the drive shaft 23
to permit the drive shaft 23 to rotate. Therefore, the hydrogen
off-gas drawn into the pump chamber 17 might enter the motor
chamber 13 through the gaps. Since the hydrogen gas (hydrogen
off-gas) has the characteristics to penetrate through metal, the
hydrogen off-gas might penetrate through the bearing block 16 and
the partition 12, which are made of metal material (for example,
aluminum alloy), and enter the motor chamber 13.
[0026] However, in this embodiment, since the motor chamber 13 is
filled with inert gas (nitrogen) G, that is, there is no residual
air (oxidizing gas), the hydrogen off-gas that entered the motor
chamber 13 does not generate water by a reaction with the air
(oxidizing gas). Therefore, even if hydrogen off-gas enters the
motor chamber 13, water is not generated by a reaction with air
(oxidizing gas). Therefore, members such as electric motor 29 in
the motor chamber 13 are prevented from corroding. As a result, the
performance of the hydrogen pump 10 is prevented from
deteriorating.
[0027] The inert gas (nitrogen) G in the motor chamber 13 is
prevented from leaking into the pump chamber 17 by the seal ring 37
located in the through hole 16a of the bearing block 16. The
O-rings 20, which function as the sealing members, prevent the
inert gas (nitrogen) G from leaking outside from the contact
portion between the motor housing 11 and the partition 12 and the
contact portion between the partition 12 and the bearing block 16
passing through the through hole 12a of the partition 12. The
O-rings 20 further prevent water from entering the motor chamber 13
from the contact portion between the motor housing 11 and the
partition 12 and the contact portion between the partition 12 and
the bearing block 16.
[0028] The preferred embodiment has the following advantages.
[0029] (1) Even if hydrogen off-gas enters the motor chamber 13
from the pump chamber 17, the motor chamber 13 is filled with inert
gas (nitrogen) G, that is, there is no air (oxidizing gas).
Therefore, water is not generated in the motor chamber 13 by a
reaction between hydrogen and air. Accordingly, the members such as
the electric motor 29 in the motor chamber 13 are prevented from
being corroded by water, and the performance of the hydrogen pump
10 is reliably prevented from deteriorating.
[0030] (2) Since the diffusion velocity of nitrogen that fills the
motor chamber 13 as the inert gas G is slower (about 1/3) than that
of the air, the nitrogen does not leak from the motor chamber 13
easily. Therefore, the performance of the hydrogen pump 10 is
maintained for a long period.
[0031] (3) The sealing material, which is the seal ring 37 in this
embodiment, is located in the through hole 16a of the bearing block
16 through which the drive shaft 23 extends. Therefore, the seal
ring 37 reliably prevents inert gas G in the motor chamber 13 from
leaking into the pump chamber 17 through where (through hole 16a)
the drive shaft 23 extends in the bearing block 16.
[0032] (4) The sealing member, which is the O-ring 20 in this
embodiment, is located at the contact portion between the motor
housing 11 and the partition 12. Therefore, the inert gas G in the
motor chamber 13 is reliably prevented from leaking outside from
the contact portion between the motor housing 11 and the partition
12. The O-ring 20 also prevents water from entering the motor
chamber 13 via the contact portion from the outside.
[0033] (5) The sealing member, which is the O-ring 20 in this
embodiment, is located at the contact portion between the partition
12 and the bearing block 16. Therefore, the inert gas G in the
motor chamber 13 is reliably prevented from leaking outside from
the contact portion between the partition 12 and the bearing block
16. The O-ring 20 also prevents water from entering the motor
chamber 13 via the contact portion from the outside.
[0034] The invention may be embodied in the following forms.
[0035] In the preferred embodiment, the dividing wall is formed by
the partition (dividing member) 12, which closes the opening of the
motor housing 11, and the bearing block (dividing member) 16, which
closes the opening of the pump housing 14. However, the dividing
wall may be formed by only the bearing block 16. In this case, the
bearing block 16 closes the opening of the motor housing 11 and the
opening of the pump housing 14.
[0036] In the preferred embodiment, the O-ring 20 is used as the
sealing member located at the contact portion between the motor
housing 11 and the partition 12. However, the sealing member other
than the O-ring 20 may be used as long as the sealing member
prevents inert gas G from leaking outside via the contact portion
and water from entering via the contact portion.
[0037] In the preferred embodiment, the sealing material, which is
the seal ring 37, is located in the through hole 16a of the bearing
block 16. However, the seal ring 37 may be located in the through
hole 12a of the partition 12.
[0038] In the preferred embodiment, the motor chamber 13 is filled
with the inert gas G, which is nitrogen. However, any inert gas
other than nitrogen (for example, argon, helium, neon, xenon, and
krypton) may be used as long as the inert gas does not react with
hydrogen and generate water. The motor chamber 13 may be filled
with mixed gas (for example, nitrogen and neon) that is the mixture
of several types of inert gases G.
[0039] In the preferred embodiment, the present invention is
embodied in the hydrogen pump 10, which circulates hydrogen gas
(hydrogen off-gas) in the fuel cell system. However, the present
invention may be embodied in any fluid machine (hydrogen pump)
other than that used in the fuel cell system as long as the fluid
machine draws and supplies fluid that includes hydrogen.
[0040] The present examples and embodiments are to be considered as
illustrative and not restrictive and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalence of the appended claims.
* * * * *