U.S. patent application number 10/836428 was filed with the patent office on 2004-10-14 for electric pump.
Invention is credited to Fujii, Toshiro, Suzuki, Shigeru.
Application Number | 20040202557 10/836428 |
Document ID | / |
Family ID | 33033090 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040202557 |
Kind Code |
A1 |
Suzuki, Shigeru ; et
al. |
October 14, 2004 |
Electric pump
Abstract
An electric pump draws and discharges fluid. When the fluid
receives heat from the pump, the fluid has a saturation vapor
pressure that can surpass the pressure of fluid that is drawn into
the pump and is lower than the pressure of fluid discharged from
the pump. The pump includes an electric motor; a pump section that
is driven by the electric motor to draw, pressurize, and discharge
the fluid; and a housing for accommodating the pump section. The
housing defines a motor chamber that accommodates the electric
motor. The pressure in the motor chamber is equal to the pressure
of fluid that is discharged from the pump section. Therefore, the
pump prevents fluid in the motor chamber from vaporizing.
Inventors: |
Suzuki, Shigeru;
(Kariya-shi, JP) ; Fujii, Toshiro; (Kariya-shi,
JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 WORLD FINANCIAL CENTER
NEW YORK
NY
10281-2101
US
|
Family ID: |
33033090 |
Appl. No.: |
10/836428 |
Filed: |
April 30, 2004 |
Current U.S.
Class: |
417/410.4 |
Current CPC
Class: |
F02M 37/08 20130101;
F02M 37/103 20130101 |
Class at
Publication: |
417/410.4 |
International
Class: |
F04B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 5, 2003 |
JP |
2003-132311 |
Feb 9, 2003 |
JP |
2003-310294 |
Dec 19, 2003 |
JP |
2003-423587 |
Claims
1. An electric pump for drawing and discharging fluid, wherein,
when the fluid receives heat from the pump, the fluid has a
saturation vapor pressure that can surpass the pressure of fluid
that is drawn into the pump and is lower than the pressure of fluid
discharged from the pump, the pump comprising: an electric motor; a
pump section that is driven by the electric motor to draw,
pressurize, and discharge the fluid; and a housing for
accommodating the pump section, wherein the housing defines a motor
chamber that accommodates the electric motor, and wherein the
pressure in the motor chamber is equal to the pressure of fluid
that is discharged from the pump section.
2. The electric pump according to claim 1, wherein fluid discharged
from the pump section is drawn into the motor chamber.
3. The electric pump according to claim 1, further comprising a
discharge path that guides fluid discharged by the pump section to
the outside of the housing, wherein the motor chamber forms part of
the discharge path.
4. The electric pump according to claim 3, wherein the housing has
a first passage and a second passage, wherein the first passage
guides fluid discharged by the pump section to the motor chamber,
and wherein the second passage guides fluid from the motor chamber
to the outside of the housing.
5. The electric pump according to claim 4, wherein the housing is
accommodated in a tank for storing fluid, and wherein, compared to
the pump section, the motor chamber is located closer to a wall of
the tank.
6. The electric pump according to claim 5, wherein a portion of the
housing that defines the motor chamber is attached to the wall of
the tank.
7. The electric pump according to claim 3, wherein a bearing for
rotatably supporting a rotary shaft of the electric motor is
provided in the housing, and wherein the discharge path passes
through the bearing.
8. The electric pump according to claim 7, wherein the bearing is
exposed to fluid that passes through the discharge path.
9. The electric pump according to claim 7, wherein the bearing has
a space that forms part of the discharge path.
10. The electric pump according to claim 1, wherein the pump is
accommodated in a tank for storing fluid, wherein the pump further
including a connection member that supports the housing with a
damper, the connection member forming part of the tank, wherein one
of the connection member and the housing has a discharge pipe, and
the other one of the connection member and the housing has a
connection hole, wherein the discharge pipe is inserted in the
connection hole, wherein the discharge pipe and the connection hole
form part of a discharge path that guides fluid discharged from the
pump section to the outside of the tank, and wherein a sealing
member is located between a circumferential surface of the
connection hole and an outer circumferential surface of the
discharge pipe.
11. The electric pump according to claim 10, wherein the discharge
pipe is formed in the connection member, and wherein the connection
hole is formed in the housing.
12. The electric pump according to claim 10, wherein the sealing
member permits the circumferential surface of the connection hole
and the outer circumferential surface of the discharge pipe to move
relative to each other.
13. The electric pump according to claim 10, wherein the sealing
member is an annular lip seal.
14. The electric pump according to claim 10, wherein the sealing
member is made of polytetrafluoroethylene.
15. The electric pump according to claim 10, wherein the housing
has an end wall that is perpendicular to a rotary shaft of the
electric motor, wherein the connection hole is formed in the end
wall, wherein one end of the rotary shaft extends into and is
rotatably supported in the connection hole, and wherein the
discharge pipe extends from the connection member toward the
connection hole.
16. The electric pump according to claim 15, wherein a bearing for
supporting the one end is located in the connection hole.
17. The electric pump according to claim 10, further comprising: a
power supply terminal for the motor, the terminal being located in
the connection member; a conductive member for electrically
connecting the power supply terminal with a stator coil of the
motor; a surrounding cylinder provided in the connection member,
wherein the surrounding cylinder surrounds at least one of the
power supply terminal and the conductive member, the surrounding
cylinder passing through the housing and extending to the motor
chamber; and a sealing member located between the surrounding
cylinder and the housing.
18. The electric pump according to claim 10, wherein the damper has
a vibration insulating rubber member, and wherein the surface of
the rubber member is coated with polytetrafluoroethylene.
19. The electric pump according to claim 18, wherein the damper
includes a first attachment member and a second attachment member,
the first and second attachment members being separated from each
other, wherein the first attachment member is fixed to the housing,
and the second attachment member is fixed to the connection member,
wherein each attachment member has a rigidity higher than that of
the rubber member, and wherein the rubber member is located between
the attachment members.
20. The electric pump according to claim 19, wherein the damper
further includes: a first screw for fixing the first attachment
member to the housing; and a second screw for fixing the second
attachment member to the connection member.
21. The electric pump according to claim 20, wherein the second
attachment member has a threaded hole, and wherein the second screw
passes through the connection member and is threaded to the second
attachment member.
22. The electric pump according to claim 19, wherein the rubber
member has a first contacting end face that faces the housing and a
second contacting end face that faces the connection member,
wherein the first attachment member is attached to the first
contacting end face, and the second attachment member is attached
to the second contacting end face.
23. The electric pump according to claim 18, wherein the sealing
member includes the rubber member.
24. The electric pump according to claim 10, wherein the damper
also functions as the seal member.
25. An electric pump for supplying dimethyl ether as fuel to an
internal combustion engine, the pump comprising: an electric motor;
a pump section driven by the electric motor; and a housing for
accommodating the pump section, wherein the housing defines a motor
chamber that accommodates the electric motor, and wherein the
pressure in the motor chamber is equal to the pressure of dimethyl
ether that is discharged from the pump section.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an electric pump in which a
motor chamber is defined in a housing that accommodates a pump
section, and an electric motor for driving the pump section is
accommodated in the motor chamber. Particularly, the present
invention pertains to an electric pump in which the saturation
vapor pressure of fluid that is drawn and pressurized by a pump
section can surpass a suction pressure of the pump section
according to a temperature increase in a motor chamber, and in
which the saturation vapor pressure has a property of being less
than a discharge pressure of the pump section due to heat in the
motor chamber.
[0002] A typical electric pump is used in a fuel supply system of
an internal combustion engine that uses dimethyl ether
(hereinafter, referred to as DME) as the fuel (for example,
Japanese Laid-Open Patent Publication No. 2003-83188). Japanese
Laid-Open Patent Publication No. 2003-83188 discloses an in-tank
pump that includes an electric pump accommodated in a fuel tank.
The electric pump has a motor chamber opened to the interior of the
fuel tank. Therefore, the electric motor is cooled with DME the
temperature of which is relatively low.
[0003] Similar in-tank pumps are disclosed in Japanese Laid-Open
Patent Publications No. 1-151765, No. 6-288313, and No. 2002-98018.
In each of these prior art systems, a discharge pipe is connected
to a lid that forms part of a tank. A rubber flexible hose is
connected to the pump. The hose is also connected to the pipe in
the tank.
[0004] Since the motor chamber is opened to the interior of the
fuel tank, the motor chamber is exposed to a suction pressure of
the pump section. In this configuration, a great amount of DME is
vaporized in the motor chamber due to the characteristics of DME
(heating the motor chamber causes the saturation vapor pressure of
DME to surpass the suction pressure). A considerable amount of
vaporized DME in the motor chamber reduces the heat exchanger
effectiveness between DME and heat producing portions of the
electric motor, which results in an insufficient cooling of the
electric motor.
[0005] Therefore, the housing of the electric motor needs to have a
vent passage that vents vaporized DME from the motor chamber to the
fuel tank. When forming a vent passage in the housing, the vent
passage needs to be located above a portion of the motor chamber in
which vaporized DME collects, so that vaporized DME is effectively
vented from the motor chamber. Accordingly, the position and the
orientation of the electric pump relative to the fuel tank are
limited according to the position of the vent passage formed in the
housing. This reduces the versatility of the electric pump.
[0006] Also, the flexible hose, which functions as part of a
discharge passage, is connected to the pipe by fitting the pipe
into the hose. At the joint of the hose and the pipe, the hose
needs to be fastened with a clip. In this manner, a section of the
discharge passage corresponding to the pipe and a section of the
discharge passage corresponding to the flexible hose are connected.
This configuration increases the space in the tank for
accommodating the pump, and complicates the connecting process.
SUMMARY OF THE INVENTION
[0007] Accordingly, it is an objective of the present invention to
provide an improved electric pump that is capable of preventing
fluid in a motor chamber from vaporizing.
[0008] To achieve the above-mentioned objective, the present
invention provides an electric pump for drawing and discharging
fluid. When the fluid receives heat from the pump, the fluid has a
saturation vapor pressure that can surpass the pressure of fluid
that is drawn into the pump and is lower than the pressure of fluid
discharged from the pump. The pump includes an electric motor; a
pump section that is driven by the electric motor to draw,
pressurize, and discharge the fluid; and a housing for
accommodating the pump section. The housing defines a motor chamber
that accommodates the electric motor. The pressure in the motor
chamber is equal to the pressure of fluid that is discharged from
the pump section.
[0009] 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
[0010] 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:
[0011] FIG. 1 is a cross-sectional view illustrating an electric
pump according to a first embodiment of the present invention;
[0012] FIG. 2 is a cross-sectional view taken along line II-II in
FIG. 1;
[0013] FIG. 3 is a diagrammatic view showing a fuel supply
system;
[0014] FIG. 4 is a graph showing the saturation vapor pressure of
DME;
[0015] FIG. 5 is a cross-sectional view illustrating an electric
pump according to a modification of the first embodiment;
[0016] FIG. 6(a) is a diagrammatic view showing a fuel supply
system according to a second embodiment of the present
invention;
[0017] FIG. 6(b) is a cross-sectional view illustrating the
electric pump of FIG. 6(a);
[0018] FIG. 7 is an enlarged partial cross-sectional view of the
electric pump shown in FIG. 6(b);
[0019] FIG. 8 is an enlarged partial cross-sectional view of the
electric pump shown in FIG. 6(b);
[0020] FIG. 9 is an enlarged view showing the tension spring of
FIG. 6(b);
[0021] FIG. 10 is a cross-sectional view taken along line A-A in
FIG. 6(b);
[0022] FIG. 11 is a cross-sectional view taken along line B-B in
FIG. 6(b);
[0023] FIG. 12 is a cross-sectional view illustrating a third
embodiment of the present invention;
[0024] FIG. 13(a) is a cross-sectional view illustrating an
electric pump according to a fourth embodiment of the present
invention;
[0025] FIG. 13(b) is an enlarged partial cross-sectional view of
the electric pump shown in FIG. 13(a);
[0026] FIG. 14(a) is a cross-sectional view taken along line D-D in
FIG. 13(a);
[0027] FIG. 14(b) is an enlarged partial cross-sectional view of
FIG. 14(a);
[0028] FIG. 15(a) is a partial cross-sectional view illustrating a
fifth embodiment of the present invention;
[0029] FIG. 15(b) is an enlarged partial cross-sectional view of
FIG. 15(a);
[0030] FIG. 16 is an enlarged cross-sectional view illustrating a
sixth embodiment of the present invention;
[0031] FIG. 17 is an enlarged cross-sectional view illustrating a
seventh embodiment of the present invention;
[0032] FIG. 18 is an enlarged cross-sectional view illustrating an
eighth embodiment of the present invention;
[0033] FIG. 19 is an enlarged cross-sectional view illustrating a
ninth embodiment of the present invention;
[0034] FIG. 20(a) is a partial cross-sectional view illustrating an
electric pump according to a tenth embodiment of the present
invention; and
[0035] FIG. 20(b) is an enlarged partial cross-sectional view of
FIG. 20(a).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] A first embodiment of the present invention will now be
described with reference to FIGS. 1 to 4.
[0037] As shown in FIG. 3, a diesel type internal combustion engine
34, which functions as a driving source of a vehicle, has a fuel
supply system. The fuel supply system includes an electric pump 2.
The entire electric pump 2 is an in-tank pump that is substantially
entirely accommodated in a bottom portion of a tank 10, in which
DME, or fluid (fuel), is stored. A suction side of the electric
pump 2 is opened to the interior of the tank 10. A discharge side
of the pump 2 is connected to a fuel injection pump 31 with a
discharge pipe 30. The discharge side of the fuel injection pump 31
is connected to the engine 34. The fuel injection pump 31 receives
pressurized DME from the electric pump 2, and sends the DME to the
engine 34 under a high pressure. Surplus DME in the fuel injection
pump 31 is returned to the tank 10 through a return passage 4a.
[0038] As shown in FIG. 1, the electric pump 2 has a connection
member 11 and an accommodation case 8. In a state where the pump 2
is installed in the tank 10, the connection member 11 is exposed to
the outside of the tank 10. The accommodation case 8 is fixed with
bolts (not shown) to a side of the connection member 11 that faces
inward of the tank 10. An inlet forming ring 9 is formed in a wall
10a, or a sidewall of the tank 10. The electric pump 2 is fixed to
the inlet forming ring 9. The electric pump 2 is installed in the
tank 10 by securing radially end portions of the connection member
11 to the inlet forming ring 9 with screws 12 such that the
accommodation case 8 is located inside the tank 10.
[0039] The accommodation case 8 includes a lid 16, a motor housing
15, and a gear housing 17, which are arranged in this order from
the connection member 11. In this embodiment, the motor housing 15,
the gear housing 17, the lid 16 and the connection member 11 form a
pump housing 6, or a housing of the electric pump 2. The motor
housing 15 is fixed to the connection member 11 with bolts (not
shown). The lid 16 is held between the proximal end (left end as
viewed in FIG. 1) of the motor housing 15 and the connection member
11. The position of the gear housing 17 is determined by
positioning pins 51. In this state, the gear housing 17 is fixed to
the distal end (right end as viewed in FIG. 1) by bolts (not
shown).
[0040] A motor chamber 152 is defined inside the motor housing 15.
An electric motor M, which functions as a drive source of the
electric pump 2, is accommodated in the motor chamber 152. The
electric motor M includes a stator 21 and a rotor 22. The stator 21
has a coil 211 and fixed to the inner surface of the motor housing
15. The rotor 22 has an iron core and rotates relative to the
stator 21. A space (gap) 57 exists between the stator 21 and the
rotor 22. Recesses 58 are formed on a surface of the stator 21 that
faces the motor housing 15. The recesses 58 are arranged along the
circumferential direction.
[0041] A rotary shaft 18 is fixed to the rotor 22 such that the
rotary shaft 18 rotates integrally with the rotor 22. The rotary
shaft 18, which functions as a motor shaft, extends between the lid
16 and the gear housing 17. A connection hole 161 is formed in the
lid 16. A radial bearing 19 is located in the connection hole 161
and supports a proximal end portion 181 of the rotary shaft 18. A
distal end of the rotary shaft 18 is supported by a needle bearing
20 accommodated in the gear housing 17. The coil 211 of the stator
21 is connected to terminals 39, 40 (wiring of which is not shown
in FIG. 1) provided in the connection member 11. When current is
supplied to the coil 211 through the terminals 39, 40, the rotary
shaft 18 rotates due to electromagnetic induction between the coil
211 and the iron core.
[0042] A pump section P, which is a gear pump, is located in an
interior of a joint of the motor housing 15 and the gear housing
17. The pump section P includes a gear train 53 that rotates when
the rotary shaft 18 rotates. The gear train 53 has a drive gear 23
and a driven gear 24. The drive gear 23 is fixed to the distal end
of the rotary shaft 18. The driven gear 24 is integrally formed
with a support shaft 241 and is meshed with the drive gear 23. As
shown in FIGS. 1 and 2, a key 56 is attached to the distal
circumferential surface of the rotary shaft 18. The key 56 extends
along the axis of the rotary shaft 18. The drive gear 23 is engaged
with the key 56.
[0043] In the interior of the distal portion of the electric pump
2, a set of pump chambers 27 are defined between the teeth of drive
gear 23 and an upper section of the inner circumferential surface
of the gear housing 17. Another set of pump chambers 27 are defined
between the teeth of driven gear 24 and a lower section of the
inner circumferential surface of the gear housing 17. The pump
chambers 27 function as pressurizing passages for DME. Also, a
shaft chamber 60 for accommodating the distal end of the rotary
shaft 18 is defined in the interior of the distal portion of the
electric pump 2. The shaft chamber 60 extends through the motor
housing 15 and the gear housing 17.
[0044] The support shaft 241 is arranged parallel to the rotary
shaft 18. One end of the support shaft 241 is supported by the
motor housing 15 with a needle bearing 25, and the other end is
supported by the gear housing 17 with a needle bearing 26. When the
rotary shaft 18 rotates, the support shaft 241 rotates following
the rotation of the rotary shaft 18 with the drive gear 23 and the
driven gear 24.
[0045] As shown in FIG. 2, spaces exist frontward and rearward of
the meshed sections of the drive gear 23 and the driven gear 24 in
the gear housing 17. Accordingly, a suction chamber 271 and a
discharge chamber 272, or a discharge side of the pump section P
are defined. DME passes through the suction chamber 271 and the
discharge chamber 272. A suction port 55 is formed in the gear
housing 17 to connect the suction chamber 271 with the outside of
the pump 2, or the interior of the tank 10 outside the pump housing
6. A discharge passage 172 is formed in an end wall 151 of the
motor housing 15 that contacts the gear housing 17. The discharge
passage 172 functions as an introducing passage, or a first
passage, that connects the discharge chamber 272 with the motor
chamber 152.
[0046] When the rotary shaft 18 rotates in a direction indicated by
an arrow (clockwise direction), the support shaft 241 rotates
following rotation of the rotary shaft 18. That is, the support
shaft 241 rotates in a direction indicated by a hollow arrow. At
this time, DME in the tank 10 flows into the suction chamber 271
from the suction port 55. The DME then flows through the pump
chambers 27, while being pressurized. After reaching the discharge
chamber 272, the DME flows out to the motor chamber 152 through the
discharge passage 172.
[0047] As shown in FIG. 1, an annular space 59 is defined in the
lid 16 at a side of the radial bearing 19 that faces the motor
chamber 152. A connection hole 161 is also formed in the lid 16 at
a side of the radial bearing 19 that faces the connection member
11. The connection hole 161 communicates with the space 59 and is
open to the side of the connection member 11. The connection member
11 has a pipe joint 29 to which the discharge pipe 30 (see FIG. 3)
from the fuel injection pump 31 is connected. A discharge port 61
is formed in the connection member 11 and the pipe joint 29. The
discharge port 61 connects the connection hole 161 with the outside
of the tank 10. In this embodiment, the space 59, the connection
hole 161, and the discharge port 61 form a lead-out passage, or a
second passage that connects the motor chamber 152 to the outside
of the pump housing 6, or the outside of the tank 10. Further, the
discharge passage 172, the space 59, the connection hole 161, and
the discharge port 61 form a discharge path.
[0048] In the motor chamber 152, the space 57 between the stator 21
and the rotor 22, and the recesses 58 of the stator 21 form a
discharge channel for DME sent to the motor chamber 152 from the
pump section P. The space 59 of the lid 16, a space between an
outer ring 191 and an inner ring 192 of the radial bearing 19, and
the connection hole 161 of the lid 16 form a discharge channel when
DME that flows out from the space 57 and the recesses 58 reaches
the discharge port 61. DME in the motor chamber 152 is sent to the
fuel injection pump 31 through the discharge port 61 and the
discharge pipe 30. As described above, the motor chamber 152 forms
part of the discharge path of DME. Therefore, the motor chamber 152
is exposed to the discharge pressure of the pump section P, or the
pressure in the discharge chamber 272.
[0049] As shown in FIG. 4, DME has a property that, when expressed
in a graph with a horizontal axis of temperature (.degree. C.) and
a vertical axis of pressure (MPa), the saturation vapor pressure of
DME is a quadric curve. When the point defined by the pressure and
the temperature of DME is located in an area above the quadric
curve, DME is liquid. When the point is below the quadric curve,
DME is gas. In the graph of FIG. 4, Pin represents the suction
pressure of the electric pump 2 (pump section P), or the pressure
in the suction chamber 271. In this embodiment, Pin is 1 MPa. Pout
represents the discharge pressure of the electric pump 2 (pump
section P). In this embodiment, Pin is 3 MPa.
[0050] When the electric pump 2 is in a normal operation state that
corresponds to a low or intermediate speed of the vehicle, the
temperature of DME in the motor chamber 152 is approximately
40.degree. C. to 50.degree. C. at the maximum. In these
temperatures, the saturation vapor pressure of DME is in a range
from approximately 0.8 MPa to value slightly higher than 1 MPa as
shown in the graph of FIG. 4. When the electric pump 2 is in a
harsh operation state that corresponds to a high speed or an abrupt
acceleration speed of the vehicle, the temperature of DME in the
motor chamber 152 is increased to approximately 80.degree. C. at
the maximum. When the temperature is increased approximately
80.degree. C., the saturation vapor pressure of DME in the motor
chamber 152 surpasses the suction pressure Pin. However, as obvious
from the graph of FIG. 4, even if the DME temperature is increased
to approximately 80.degree. C., the saturation vapor pressure does
not exceed the discharge pressure Pout.
[0051] Accordingly, DME, which is used in the electric pump 2 of
this embodiment, has the following property. That is, when DME is
heated according to a temperature increase in the motor chamber
152, the saturation vapor pressure of DME can surpass the suction
pressure Pin of the pump section P. At the same time, despite the
temperature increase in the motor chamber 152, the saturation vapor
pressure stays below the discharge pressure Pout of the pump
section P. Therefore, in this embodiment in which the motor chamber
152 is exposed to the discharge pressure, even if the saturation
vapor pressure DME is increased due to a temperature increase, the
pressure in the motor chamber 152 does not fall below the
saturation vapor pressure. Thus, DME is not vaporized in the motor
chamber 152.
[0052] Accordingly, unlike the system disclosed in Japanese
Laid-Open Patent Publication 2003-83188, the present embodiment
does not require a vent passage for venting DME from a motor
chamber to a tank. Therefore, the position and the orientation of
the electric pump 2 relative to the tank 10 are not limited. As a
result, the electric pump 2 is versatile (advantage (1)).
[0053] Other than the advantage (1), the above embodiment provides
the following advantages.
[0054] (2) The motor chamber 152 forms part of the discharge path
of DME from the pump section P to the outside of the pump housing
6, or the outside of the tank 10. Therefore, a flow of DME from the
pump section P to the outside of the pump housing 6 is generated in
the motor chamber 152. This permits the electric motor M to be
effectively cooled with DME.
[0055] (3) The electric pump 2 is of an in-tank type. That is, the
motor chamber 152 is located adjacent to the wall 10a of the tank
10, and the pump section P is located on the opposite side of the
motor chamber 152 from the wall 10a. In other words, a portion of
the pump housing 6 that defines the motor chamber 152 is attached
to the wall 10a. Since the motor chamber 152 is located close to
the wall 10a of the tank 10, the lead-out passage, or the second
passage from the motor chamber 152 to the outside of the tank 10 is
short and simple. In other words, since the motor chamber 152 is
used as the part of the discharge path of DME from the pump section
P to the outside of the pump housing 6, the layout of this
embodiment is applied without complicating the routing of the
lead-out passage.
[0056] (4) The discharge path of DME from the pump section P to the
outside of the pump housing 6 passes through the radial bearing 19,
which rotatably supports the rotary shaft (drive shaft) 18. Thus,
the radial bearing 19 is exposed to a flow of DME and is
effectively cooled with DME.
[0057] (5) The passage of DME when passing through the electric
motor M in the motor chamber 152 is defined not only by the space
57 between the stator 21 and the rotor 22, but also the recesses 58
on the circumferential surface of the stator 21. Thus, compared to
the case where the passage is defined only by the space 57, the
discharge path of DME is broadened.
[0058] (6) The shaft chamber 60 is exposed to the discharge
pressure. Thus, leakage of DME from the pump chamber 27 to the
shaft chamber 60 is suppressed.
[0059] In the above embodiment, the electric pump 2 includes the
single-stage pump section P. However, the present invention is not
limited to electric pumps having a single-stage pump section, but
may be embodied in electric pumps having a multi-stage pump
section, such as a two-stage pump section shown in FIG. 5.
[0060] A second embodiment according to the present invention will
now be described with reference to FIGS. 6(a) to 11. As shown in
FIG. 6(a), a connection member 11 is fixed to an upper wall 101 of
a tank 10 with screws 12. As shown in FIG. 6(b), the connection
member 11, which forms part of the tank 10, covers an insertion
hole 102.
[0061] In this embodiment, the motor housing 15, the gear housing
17 and the lid 16 form a pump housing 7, or a housing of the
electric pump 13. Below the connection member 11, the pump housing
7 is suspended with tension springs 14, the number of which is
three in this embodiment.
[0062] A suction chamber 271, which is shown in FIG. 10, is
connected to the interior of the tank 10 through a suction passage
171. A discharge chamber 272 of the pump chamber 27 is connected to
the interior of the motor housing 15 (the motor chamber 152)
through a discharge passage 172.
[0063] The rotary shaft 18 rotates in a direction indicated by an
arrow R in FIG. 10. When the rotary shaft 18 rotates, the drive
gear 23 rotates integrally with the rotary shaft 18. Accordingly,
the driven gear 24, while being meshed with the drive gear 23,
rotates in a direction indicated by an arrow Q in FIG. 10. When the
drive gear 23 and the driven gear 24 rotate, fluid F (dimethyl
ether) in the tank 10 is drawn into the suction chamber 271 through
the suction passage 171.
[0064] An upper end 141 of each spring 14 is hooked to the
connection member 11 as shown in FIG. 9. A lower end 142 of each
spring 14 is hooked to a screw 43 in a recess 164 formed in the
upper surface of the lid 16. When transmitted to the connection
member 11, vibration of the electric pump 13, or vibration of the
pump housing 7 generates noise. However, the tension springs 14
function as vibration prevention mechanism (dumper) that prevents
vibration of the electric pump 13 from being transmitted to the
connection member 11.
[0065] As shown in FIG. 6(b), a discharge pipe 28 is integrally
formed with and projects from a center of the lower surface of the
connection member 11. A pipe joint 29 is attached to a center of
the upper surface of the connection member 11. A channel 291 in the
pipe joint 29 communicates with a discharge passage 281 in the
discharge pipe 28. As shown in FIG. 6(a), the discharge pipe 30 is
connected to the pipe joint 29. The discharge pipe 30 is connected
to the fuel injection pump 31.
[0066] As shown in FIGS. 6(b) and 7, the discharge pipe 28 is
inserted in the connection hole 161 so that the discharge passage
281 communicates with the connection hole 161. A sealing member,
which is a lip seal 32, is located between a circumferential
surface 162 of the connection hole 161 and an outer circumferential
surface 282 of the discharge pipe 28. The lip seal 32 includes an
annular case 321, a pair of retainer rings 322, 323, and a lip ring
324 held between the retainer rings 322, 323. The lip ring 324 is
made of polytetrafluorethylene. The case 321 is fitted in the
connection hole 161. The position of the case 321 is determined by
a snap ring 33 fitted to a circumferential surface 162 of the
connection hole 161. The lip ring 324 contacts the outer
circumferential surface 282 of the discharge pipe 28.
[0067] Fluid F in the motor chamber 152 is sent to the discharge
passage 281 via space between the outer ring 191 and the inner ring
192 of the radial bearing 19, and the connection hole 161. Fluid F
in the discharge passage 281 is sent to the fuel injection pump 31
via the channel 291 in the pipe joint 29 and the discharge pipe 30.
The fuel injection pump 31 receives fluid F, and sends the fluid F
to the engine 34 shown in FIG. 6(a).
[0068] As shown in FIG. 6(b), a surrounding cylinder 35 projects
and integrally formed with the lower surface of the connection
member 11. A through hole 163 is formed in the lid 16, and the
surrounding cylinder 35 is inserted in the through hole 163. A
sealing member, which is a lip seal 36, is located between an outer
circumferential surface 352 of the surrounding cylinder 35 and a
circumferential surface 166 of the through hole 163. As shown in
FIG. 8, the lip seal 36 includes an annular case 361, a pair of
retainer rings 362, 363, and a lip ring 364 held between the
retainer rings 362, 363. The lip ring 364 is made of
polytetrafluorethylene. The case 361 is fitted in the through hole
163. The position of the case 361 is determined by a snap ring 37
fitted to a circumferential surface 166 of the through hole 163.
The lip ring 364 contacts an outer circumferential surface 352 of
the surrounding cylinder 35.
[0069] As shown in FIG. 6(b), the surrounding cylinder 35 has a
wiring hole 351 that passes through the connection member 11. A
cup-shaped shutter 38 is fitted in the wiring hole 351. The
terminals 39, 40 pass through and are fixed to the bottom wall of
the shutter 38. The stator 21 and the inner ends of the terminals
39, 40 are electrically connected to each other with conductive
members, which are lead wires 41. The outer ends of the terminals
39, 40 are electrically connected to a power supply (not shown).
The position of the shutter 38 is determined by a snap ring 42
fitted to a circumferential surface of the wiring hole 351. The
shutter 38 disconnects the interior of the motor housing 15 (the
motor chamber 152) and the outside of the tank 10.
[0070] The pressure of the interior of the motor housing 15 is
higher than the pressure in the tank 10 outside the motor housing
15. The pressure difference presses the lip ring 324 of the lip
seal 32 against the outer circumferential surface 282 of the
discharge pipe 28. The pressure difference also presses the lip
ring 364 of the lip seal 36 against the outer circumferential
surface 352 of the surrounding cylinder 35. The interior of the
motor housing 15 (the motor chamber 152) is disconnected from the
interior of the tank 10 outside the pump housing 7 by the lip seals
32, 36.
[0071] The pump housing 7, or the main body of the electric pump 13
is attached to the connection member 11 before being installed in
the tank 10. Before attaching the pump housing 7 to the connection
member 11, the lead wires 41 are not connected to the terminals 39,
40, and the shutter 38 is not attached to the connection member 11.
The attachment is carried out in the following manner. First, the
lead wires 41 are drawn through the wiring hole 351 from the
surrounding cylinder 35. The length of the lead wires 41 are
determined such that a sufficient length of each lead wire 41 is
drawn from the wiring hole 351. In this state, the lip seal 32 is
fitted in the discharge pipe 28, and the lip seal 36 is fitted in
the surrounding cylinder 35. In a state where the discharge pipe 28
is fitted in the lip seal 32 and the surrounding cylinder 35 is
fitted in the lip seal 36, the lower ends 142 of the tension
springs 14 are inserted in the recesses 164. Then, each screw 43 is
threaded into a threaded hole 165 such that the screw 43 crosses
the corresponding recess 164.
[0072] Next, the lead wires 41, which have been drawn out of the
wiring hole 351, are soldered to the terminals 39, 40. Thereafter,
the shutter 38 is fitted in the wiring hole 351 and fixed with the
snap ring 42. In a state where the shutter 38 is fitted in and
fixed to the wiring hole 351, pressurized fluid F in the motor
chamber 152 does not leak to the outside of the tank 10 through the
wiring hole 351.
[0073] In this manner, the pump housing 7 is attached to the
connection member 11. The pump housing 7 is then placed in the tank
10 through the insertion hole 102. The connection member 11, to
which the pump housing 7 is attached, is fastened to the upper wall
101 of the tank 10 with the screws 12.
[0074] The second embodiment provides the following advantages
besides the advantages (1) to (6) of the first embodiment.
[0075] (2-1) In a state where the pump housing 7 is attached to the
connection member 11, which forms part of the tank 10, the space
between the circumferential surface 162 of the connection hole 161
and the outer circumferential surface 282 of the discharge pipe 28
is sealed with the lip seal 32, and the space between the
circumferential surface 166 of the through hole 163 and the outer
circumferential surface 352 of the surrounding cylinder 35 is
sealed with the lip seal 36. That is, the discharge pipe 28 is
connected to the connection hole 161, and the surrounding cylinder
35 is connected to the through hole 163. In a state where the
discharge pipe 28 is connected to the connection hole 161,
pressurized fluid F in the motor chamber 152 does not leak to the
interior of the tank 10 through the connection hole 161. Also, in a
state where the surrounding cylinder 35 is connected to the through
hole 163, pressurized fluid F in the motor chamber 152 does not
leak to the interior of the tank 10 through the through hole
163.
[0076] The connection of the discharge pipe 28 and the connection
hole 161 and the connection of the surrounding cylinder 35 and the
through hole 163 are completed by a simple process in which the
discharge pipe 28 is inserted into the connection hole 161 and the
surrounding cylinder 35 is inserted in the through hole 163.
[0077] (2-2) The lip seals 32, 36, which exert sealing performance
using pressure differences, are favorable as sealing members for
preventing pressurized fluid F in the motor chamber 152 from
leaking into the interior of the tank 10. The lip rings 324, 364 of
the lip seals 32, 36 prevent vibration of the electric pump 13 (the
pump housing 7) from being transmitted to the connection member 11.
Dimethyl ether damages rubber. That is, the dimethyl ether causes
rubber to harden or swell, which can result in breakage. However,
since the lip rings 324, 364 are made of polytetrafluoroethylene,
dimethyl ether does not damage the lip rings 324, 364. Accordingly,
the damping property of the lip rings 324, 364 does not
deteriorate.
[0078] (2-3) The rotary shaft 18 is rotatably supported in the
connection hole 161 formed in the lid 16. That is, a hole for
rotatably supporting the rotary shaft 18, which is the connection
hole 161, is also used as a connection hole for connecting the
interior of the motor housing 15 (the motor chamber 152) with the
discharge passage 281 of the discharge pipe 28. In this structure
where a single hole is used for two purposes, no additional
connection hole is required. This simplifies the structure.
[0079] (2-4) The power supply terminals for the motor M, which are
the terminals 39, 40, are electrically connected to the stator 21
with the lead wires 41. The lip seal 36 is located between the lid
16 and the surrounding cylinder 35, which surrounds the lead wires
41. This structure is favorable for guaranteeing the sealing
property about the lead wires 41.
[0080] (2-5) Unlike Japanese Laid-Open Patent Publications No.
1-151765, No. 6-288313, No. 2002-98018, no flexible hose is used
for connecting a section of the discharge path in the connection
member 11 with a section of the discharge path in the pump housing
7 (the motor chamber 152 in this embodiment). A connection
structure using a flexible tube enlarges the space occupied by a
pump in a tank. However, since no flexible tube is used in this
embodiment, such a problem is avoided.
[0081] (2-6) To facilitate the attachment of the pump housing 7
(the main body of the electric pump 13) to the connection member
11, it is preferably that the tension spring 14 be easily attached
to either one of the pump housing 7 and the connection member 11
during the attaching process. In this embodiment, after the lower
end 142 of each tension spring 14 is inserted in the corresponding
recess 164 formed in the lid 16 of the pump housing 7, the spring
14 is coupled to the pump housing 7 simply by threading the screw
43 in the corresponding threaded hole 165 of the lid 16. The
attachment of the springs 14 is thus simple.
[0082] A third embodiment of the present invention will now be
described with reference to FIG. 12. In the third embodiment, like
or the same reference numerals are given to those components that
are like or the same as the corresponding components of the second
embodiment.
[0083] The pump housing 7 is suspended from the connection member
11 with vibration insulators 65 (only one is shown in FIG. 12) in
between. The vibration insulators 65, which function as dampers are
located about the axis of the rotary shaft 18. The vibration
insulators 65 are made of polytetrafluorethylene. The vibration
insulators 65 are adhered to the upper surface of the lid 16 and to
the lower surface of the connection member 11. The vibration
insulators 65 prevent vibration of the pump housing 7 from being
transmitted to the connection member 11.
[0084] When attaching the pump housing 7 (the electric motor M) to
the connection member 11, a face of each vibration insulator 65 is
adhered to one of the electric motor M and the connection member
11. Adhesive is applied to the opposite face of each vibration
insulator 65. Then, the lead wires 41 are drawn out through the
wiring hole 351. In this state, the lip seal 32 is fitted in the
discharge pipe 28, and the lip seal 36 is fitted in the surrounding
cylinder 35. In a state where the discharge pipe 28 is fitted in
the lip seal 32 and the surrounding cylinder 35 is fitted in the
lip seal 36, the vibration insulators 65 are adhered to the
electric motor M and the connection member 11. Next, the lead wires
41, which have been drawn out of the wiring hole 351, are soldered
to the terminals 39, 40. Thereafter, the shutter 38 is fitted in
the wiring hole 351 and fixed with the snap ring 42.
[0085] Alternatively, the shutter 38 may be fitted in the wiring
hole 351 in advance. In this case, the lead wires 41 are connected
to the terminals 39, 40. Thereafter, the connection member 11 and
the electric motor M are brought close to each other such that the
vibration insulators 65 are adhered to the connection member
11.
[0086] The third embodiment has the same advantages as the
advantages (2-1) to (2-5) of the second embodiment.
[0087] A fourth embodiment will now be described with reference to
FIGS. 13(a), 13(b), 14(a) and 14(b).
[0088] As shown in FIGS. 13(a) and 13(b), vibration insulating
mechanism, or a damper 71 having a vibration insulating rubber
member 70 is located between the lid 16 of the pump housing 7 and
the connection member 11. As shown in FIG. 13(b), the damper 71
includes the rubber member 70, a coupling member 72, a threaded
hole forming member 73, a pair of first screws 74, and a second
screw 75. The first screws 74 are used to fasten the coupling
member 72, which functions as a first attachment member, with the
lid 16. The second screw 75 is used to fasten the threaded hole
forming member 73, which functions as a second attachment member,
to the connection member 11. The coupling member 72 contacts and is
attached to a first contacting end face 701 of the rubber member 70
that faces the pump housing 7. The thread hole forming member 73
includes a nut portion 731 having a threaded hole, and a coupling
plate portion 732 coupled to the nut portion 731. The nut portion
731 is embedded in the rubber member 70. The coupling plate portion
732 is attached to a second contacting end face 702 of the rubber
member 70 that faces the connection member 11.
[0089] The coupling member 72 is fastened to the upper surface of
the lid 16 with the first screws 74 threaded to the lid 16. The
threaded hole forming member 73 is fastened to the lower surface of
the connection member 11 with the second screw 75, which is passed
through a through hole 113 formed in the connection member 11 and
is threaded to the nut portion 731. That is, the damper 71 is
attached to the lid 16 with the coupling member 72, and is also
attached to the connection member 11 with the threaded hole forming
member 73.
[0090] As shown in FIG. 14(a), two or more sets (three in this
embodiment) of the dampers 71 are provided about the discharge pipe
28. The sets of the dampers 71, which are attached to the
connection member 11, suspend the pump housing 7.
[0091] As shown in FIGS. 13(b) and 14(b), a polytetrafluoroethylene
coating layer 76 is formed on a surface of each vibration
insulating rubber member 70 (a circumferential surface 703 in this
embodiment). Also, the coating layer 76 is formed on the surface of
each coupling member 72 and the surface of each threaded hole
forming member 73. Each vibration insulating rubber member 70 is
covered with the coating layer 76 so that the surface of the rubber
member 70 is not exposed.
[0092] The fourth embodiment provides the following advantages.
[0093] (4-1) The rubber members 70 prevent vibration of the pump
housing 7 from being transmitted to the connection member 11. Part
of the surface of each vibration insulating rubber member 70 is not
covered with the coupling member 72 and the threaded hole forming
member 73. Such part of the surface is covered with the
polytetrafluoroethylene coating layer 76. That is, the surface of
each vibration insulating rubber member 70 is not exposed to
dimethyl ether, which is a liquefied gas fuel. Therefore, when the
pump housing 7 is suspended in the tank 10 storing dimethyl ether
by using the damper 71, the rubber members 70 do not
deteriorate.
[0094] (4-2) Each damper 71 is attached to the lid 16 and the
connection member 11 in the following manner. First, the first
screws 74 are threaded to fasten the coupling member 72 to the lid
16. Then, the second screw 75 is passed through the through hole
113 and threaded to the nut portion 731 of the threaded hole
forming member 73. That is, each damper 71, in which the coupling
member 72 and the threaded hole forming member 73 are coupled to
the rubber member 70, is easily installed between the pump housing
7 and the connection member 11.
[0095] A fifth embodiment will now be described with reference to
FIGS. 15(a) and 15(b).
[0096] As shown in FIG. 15(a), dampers 78 having a cylindrical
vibration insulating rubber member 77 is located between the lid 16
of the pump housing 7 and the connection member 11. As shown in
FIG. 15(b), the damper 78 includes the rubber member 77, a coupling
member 79, a threaded hole forming member 80, a first screw 81, and
the second screw 75. The first screw 81 is used to fasten the
coupling member 79, which functions as a first attachment member,
to the lid 16. The second screw 75 is used to fasten the threaded
hole forming member 80, which functions as a second attachment
member, to the connection member 11. The coupling member 79
contacts and is attached to a first contacting end face 771 of the
rubber member 77. The thread hole forming member 80 includes a nut
portion 801 having a threaded hole, and a coupling plate portion
802 coupled to the nut portion 801. The nut portion 801 is fitted
in an inner surface 773 of the rubber member 77. The coupling plate
portion 802 is attached to a second contacting end face 772 of the
rubber member 77.
[0097] The coupling member 79 is fastened to the upper surface of
the lid 16 with the first screw 81 threaded to the lid 16. The
threaded hole forming member 80 is fastened to the lower surface of
the connection member 11 with the second screw 75, which is passed
through a through hole 113 formed in the connection member 11 and
is threaded to the nut portion 801. That is, the damper 78 is
attached to the lid 16 with the coupling member 79, and is also
attached to the connection member 11 with the threaded hole forming
member 80.
[0098] The inner diameter of the nut portion 801 of the threaded
hole forming member 80 and the inner diameter of the rubber member
77 are greater than the diameter of the head of the first screw 81.
Therefore, the first screw 81 can be threaded to the lid 16 through
the nut portion 801 and the rubber member 77.
[0099] As shown in FIG. 15(b), a polytetrafluoroethylene coating
layer 82 is formed on a surface of the rubber member 77 and on an
inner surface 773 of the rubber member 77. Also, the coating layer
82 is formed on the surface of the coupling member 79 and the
surface of the threaded hole forming member 80. The rubber member
77 is covered with the coating layer 82 so that the surface of the
rubber member 77 is not exposed.
[0100] The damper 78 is attached to the lid 16 and the connection
member 11 in the following manner. First, the first screw 81 is
threaded to fasten the coupling member 79 to the lid 16. Then, the
second screw 75 is passed through the through hole 113 and threaded
to the nut portion 801 of the threaded hole forming member 80. That
is, the dampers 78, in which the coupling member 79 and the
threaded hole forming member 80 are coupled to the rubber member
77, is easily installed between the pump housing 7 and the
connection member 11. The fifth embodiment has the same advantage
as the advantage (4-1) of the fourth embodiment.
[0101] A sixth embodiment will now be described with reference to
FIG. 16.
[0102] A damper 83 includes a cylindrical vibration insulating
rubber member 84, a cylindrical coupling member 85, a threaded hole
forming member 86, first screws 87, and a second screw 75. The
first screws 87 are used to fasten the coupling member 85, which
functions as a first attachment member, to the lid 16. The second
screw 75 is threaded to the threaded hole forming member 86, which
functions as a second attachment member. The thread hole forming
member 86 includes a nut portion 861 having a threaded hole, and a
flange 862 coupled to the nut portion 861. The rubber member 84 is
fitted in the cylinder of the cylindrical coupling member 85. An
annular plate portion 851 of the coupling member 85 contacts an
upper end face 841 of the rubber member 84. The nut portion 861 is
fitted in the cylinder of the rubber member 84. The flange 862 is
contacts a lower end face 842 of the rubber member 84.
[0103] The flange 852 of the coupling member 85 is fastened to the
upper surface of the lid 16 with the first screws 87 threaded to
the lid 16. The second screw 75 is threaded to the nut portion 861
of the threaded hole forming member 86.
[0104] A polytetrafluoroethylene coating layer 88 is formed on the
surface of the rubber member 84. The rubber member 84 is covered
with the coating layer 88 so that the surface of the rubber member
84 is not exposed.
[0105] The sixth embodiment thus provides the same advantages as
the fourth embodiment.
[0106] A seventh embodiment will now be described with reference to
FIG. 17.
[0107] A damper 89 includes an annular vibration insulating rubber
member 90, an annular holding member 91, and screws 92. The screws
92 are used to fastening the rubber member 90 and the holding
member 91 to the pump housing 7. The insertion hole 102, which is
formed with an inlet forming ring 9, is formed in the upper wall
101 of the tank 10. A flange 901 of the rubber member 90 is held
between the inlet forming ring 9 and the connection member 11.
[0108] A polytetrafluoroethylene coating layer 94 is formed on the
surface of the rubber member 90. The rubber member 90 is covered
with the coating layer 94 so that the surface of the rubber member
90 is not exposed.
[0109] The seventh embodiment provides the same advantage as the
advantage (4-1) of the fourth embodiment.
[0110] An eighth embodiment will now be described with reference to
FIG. 18. An annular rim portion 931 is formed on the inlet forming
ring 9. An annular vibration insulating rubber member 95 is located
between the rim portion 931 and a flange 153 of the motor housing
15. A vibration insulating rubber member 95 is placed on the rim
portion 931, and the flange 153 is placed on the rubber member 95.
The rubber member 95 functions as damper that prevents vibration of
the pump housing 7 from being transmitted to the connection member
11.
[0111] A polytetrafluoroethylene coating layer 96 is formed on the
surface of the rubber member 95. The rubber member 95 is covered
with the coating layer 96 so that the surface of the rubber member
95 is not exposed.
[0112] The eighth embodiment provides the same advantage as the
advantage (4-1) of the fourth embodiment.
[0113] A ninth embodiment will now be described with reference to
FIG. 19. A head 971 of a bolt 97 and an annular washer 98 are
embedded in a vibration insulating rubber member 48. The threaded
portion of the bolt 97 passes through the through hole 113 of the
connection member 11 and protrudes to the outside of the tank 10. A
nut 99 is threaded to the projecting portion of the bolt 97. Screws
74, a coupling member 72, the rubber member 48, the bolt 97, and
the washer 98 form a damper.
[0114] A polytetrafluoroethylene coating layer 100 is formed on the
surface of the coupling member 72 and the surface of the rubber
member 48. The rubber member 48 is covered with the coating layer
100 so that the surface of the rubber member 48 is not exposed.
[0115] The ninth embodiment thus provides the same advantages as
the fourth embodiment.
[0116] A tenth embodiment will now be described with reference to
FIGS. 20(a) and 20(b). In the tenth embodiment, the lip seal 32 and
the lip seal 36 of the second embodiment are replaced by damper 103
and damper 104, respectively.
[0117] The damper 103 includes an annular vibration insulating
rubber member 105, an annular coupling member 106, an annular
thread hole forming member 107, first screws 74, and second screws
75. The first screws 74 are used to fasten the coupling member 106,
which functions as a first attachment member, to the lid 16. The
second screws 75 are used to fasten the threaded hole forming
member 107, which functions as a second attachment member, to the
connection member 11. The discharge pipe 28 is fitted in the
annular rubber member 105. The rubber member 105 has an annular
sealing portion 1053. The sealing portion 1053 is pressed against
the circumferential surface 282 of the discharge pipe 28 by the
difference between the pressure in the motor housing 15 and the
pressure in the tank 10, so that the inner circumferential surface
of the sealing portion 1053 closely contacts the circumferential
surface 282 of the discharge pipe 28.
[0118] The coupling member 106 contacts and is attached to a first
contacting end faces 1051 of the rubber member 105. The threaded
hole forming member 107 includes an annular contacting plate
portion 1072, and nut portions 1071 each having a threaded hole.
The annular contacting plate portion 1072 surrounds the discharge
pipe 28, and the nut portions 1071 are located about the discharge
pipe 28. The nut portions 1071 are embedded in the rubber member
105. The contacting plate portion 1072 is attached to a second
contacting end face 1052 of the rubber member 105.
[0119] A polytetrafluoroethylene coating layer 108 is formed on the
surface of the rubber member 105, the coupling member 106, and the
surface of the threaded hole forming member 107. The rubber member
105 is covered with the coating layer 108 so that the surface of
the rubber member 105 is not exposed.
[0120] The coupling member 106 is fastened to the upper surface of
the lid 16 with the first screws 74 threaded to the lid 16. The
threaded hole forming member 107 is fastened to the lower surface
of the connection member 11 with the second screw 75, which is
passed through a through hole 113 formed in the connection member
11 and is threaded to the nut portion 1071.
[0121] Except for the inner diameter of the rubber member 105, the
damper 104 has the same configuration as the damper 103. Thus, like
or the same reference numerals are given to those components that
are like or the same as the corresponding components of the damper
103. The sealing portion 1053 of the damper 104 is pressed against
the circumferential surface 352 of the surrounding cylinder 35 by
the difference between the pressure in the motor housing 15 and the
pressure in the tank 10, so that the inner circumferential surface
of the sealing portion 1053 of the damper 104 closely contacts the
circumferential surface 352 of the discharge pipe 35.
[0122] The damper 103, 104 are arranged between the lid 16 and the
connection member 11 in the following manner. First, the first
screws 74 are fastened to secure the coupling member 106 to the lid
16. Then, the discharge pipe 28 is fitted in the rubber member 105
of the damper 103, and the surrounding cylinder 35 is fitted in the
rubber member 105 of the damper 104. Subsequently, the second
screws 75 are passed through the through holes 113 and threaded to
the nut portions 1071 of the through hole forming members 107 of
the damper 103, 104. Accordingly, the damper 103, 104 are attached
to the lid 16 and the connection member 11.
[0123] In the tenth embodiment, the damper 103, 104 also function
as the lip seals 32, 36 in the first embodiment. The tenth
embodiment also provides the same advantage as the advantage (4-1)
of the fourth embodiment.
[0124] The invention may be embodied in the following forms.
[0125] The lip rings of the lip seals 32, 36 may be made of
rubber.
[0126] The lip seals 32, 36 may be replaced by O-ring shaped
sealing members.
[0127] In the second to tenth embodiment of the present invention,
the pump housing 7 may be located on the bottom of a tank with
dampers in between.
[0128] The present invention may be applied to a system where a sub
tank is connected to the tank 10 through a pipe, and a pump is
located in the sub tank.
[0129] In the second embodiment of the present invention, the
electric pump may be oriented horizontally and accommodated in the
tank 10. In this case, the connection hole and the through holes
are formed in the sidewall of the motor housing 15.
[0130] The electric pump may be suspended from the connection
member 11 with elastic belts. If the belts are made of rubber, it
is preferable that the surface of the belts be coated with a layer
of polytetrafluorethylene.
[0131] The present invention may be applied to a pump that is used
in a cogeneration system (private electric generator), which
generates electricity while using exhaust heat to heat water
(fluid).
[0132] In the third embodiment, instead of using adhesive, a plate
may be welded to each side of the vibration insulator 65, so that
the electric motor M is fastened to one side with screws, and the
connection member 11 is fastened to the other side with screws.
[0133] In the illustrated embodiments, the present invention is
applied to the electric pump, which uses DME. However, the present
invention may be applied to pumps that use other types of fluid.
That is, as long as a fluid that has the above described properties
(the saturation vapor pressure can surpass the suction pressure of
the pump section due to heat of the motor chamber, and the
saturation vapor pressure stays below the discharge pressure of the
pump section despite the heat in the motor chamber) is used, the
present invention may be any electric pump that uses a fluid other
than DME.
[0134] In the first embodiment, the electric pump 2 need not be of
an in-tank type, but may be of a type that is arranged outside the
tank 10.
[0135] In the illustrated embodiments, the motor chamber 152 need
not form part of the discharge path of DME. That is, the gear
housing 17 may have a discharge port, so that the motor chamber 152
does not form part of the discharge path. In this case, the
discharge port is connected to the motor chamber 152 through the
passage 172 so that the motor chamber 152 is exposed to the
discharge pressure.
[0136] In the second to tenth embodiments, the pump housing 7 may
have the discharge pipe 28 and the connection member 11 may have
the connection hole 161.
[0137] In the illustrated embodiments, the pump section is a gear
pump. However, the pump section does not need to be a gear pump.
For example, the pump section may be a screw pump or a piston
pump.
[0138] 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.
* * * * *