U.S. patent application number 14/186689 was filed with the patent office on 2014-09-04 for electric vacuum pump.
This patent application is currently assigned to AISAN KOGYO KABUSHIKI KAISHA. The applicant listed for this patent is AISAN KOGYO KABUSHIKI KAISHA. Invention is credited to Katsuhiko MAKINO, Atsushi SUGIMOTO, Shota YAMANAKA.
Application Number | 20140248167 14/186689 |
Document ID | / |
Family ID | 51353173 |
Filed Date | 2014-09-04 |
United States Patent
Application |
20140248167 |
Kind Code |
A1 |
SUGIMOTO; Atsushi ; et
al. |
September 4, 2014 |
ELECTRIC VACUUM PUMP
Abstract
In an electric vacuum pump, a pump housing and a lower-end cover
member respectively include positioning retainers respectively
formed on outer peripheries of the pump housing and the lower-end
cover member. A case includes positioning retainers each protruding
inward from an inner peripheral surface of the case. The
positioning retainers are in contact with the positioning
protrusions, thereby positioning the pump housing and the lower-end
cover member with respect to the case. The positioning protrusions
are formed with screw holes.
Inventors: |
SUGIMOTO; Atsushi; (Obu-shi,
JP) ; MAKINO; Katsuhiko; (Chita-gun, JP) ;
YAMANAKA; Shota; (Hekinan-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AISAN KOGYO KABUSHIKI KAISHA |
Obu-shi |
|
JP |
|
|
Assignee: |
AISAN KOGYO KABUSHIKI
KAISHA
Obu-shi
JP
|
Family ID: |
51353173 |
Appl. No.: |
14/186689 |
Filed: |
February 21, 2014 |
Current U.S.
Class: |
417/410.1 |
Current CPC
Class: |
F04C 2240/30 20130101;
F04C 29/04 20130101; F04C 29/06 20130101; F04B 35/04 20130101; F04C
18/3441 20130101; F04C 25/02 20130101 |
Class at
Publication: |
417/410.1 |
International
Class: |
F04B 35/04 20060101
F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2013 |
JP |
2013-040766 |
Aug 29, 2013 |
JP |
2013-177796 |
Claims
1. An electric vacuum pump including: a case having internal space;
a motor part placed in the internal space of the case; and a pump
part placed in the internal space of the case and to be driven in
sync with the motor part, wherein the pump part includes: a
cylindrical pump housing; a first cover member placed in the pump
housing on one end side in a center axis direction of the pump
housing; a second cover member placed in the pump housing on the
other end in the center axis direction; a pump chamber formed by an
inner peripheral surface of the pump housing, the first cover
member, and the second cover member; and a rotor housed in the pump
chamber and including a plurality of vanes inserted therein, the
electric vacuum pump further includes a fastening member passed
through a through hole formed in the first cover member and being
fastened in a fastening hole formed in the case to fix the first
cover member to the case and the pump housing, the pump housing is
provided with a positioning retainer formed on an outer periphery
and the second cover member is provided with a positioning retainer
formed on an outer periphery, the case is provided with a
positioning protrusion formed to protrude inward from an inner
peripheral surface of the case, the positioning retainers are in
contact with the positioning protrusion to position the pump
housing and the second cover member with respect to the case, and
the fastening hole is formed in the positioning protrusion.
2. The electric vacuum pump according to claim 1, wherein the
positioning retainers are formed to respectively protrude from an
outer peripheral surface of the pump housing and an outer
peripheral surface of the second cover member toward the inner
peripheral surface of the case and include grooves engageable with
the positioning protrusion.
3. The electric vacuum pump according to claim 1, wherein the case
has an end face on the one end side in the center axis direction of
the pump housing, the end face being located in the same position
as an end face of the first cover member on the other end side in
the center axis direction of the pump housing or located in a
position closer to the one end side than the end face of the first
cover member on the other end side.
4. The electric vacuum pump according to claim 1, wherein the pump
part and the inner peripheral surface of the case form therebetween
a space in an area excepting the positioning protrusion and the
positioning retainers.
5. The electric vacuum pump according to claim 4, further including
a member placed in the space to produce at least one of a silencing
effect and a cooling effect.
6. The electric vacuum pump according to claim 4, wherein the case
includes a rib placed in the space and formed to protrude inward
from the inner peripheral surface of the case.
7. The electric vacuum pump according to claim 1, wherein the case,
is provided with a plurality of the positioning protrusions and a
plurality of the fastening holes in two or more and odd-numbered
pairs, and one pair of the pairs of positioning protrusions and
fastening holes is placed in a position 180.degree. opposite to a
center axis of the inner peripheral surface of the pump housing
with respect to a rotation center axis of the rotor.
8. The electric vacuum pump according to claim 1, wherein the first
cover member includes a suction inlet for sucking gas from outside
into the pump chamber and a discharge outlet for discharging gas
from the pump chamber to the outside, and the pump housing and the
first cover member are integrally formed.
9. The electric vacuum pump according to claim 1, further including
a cover closing the internal space of the case from a side of the
pump part, and the cover and the first cover member form
therebetween a space.
10. The electric vacuum pump according to claim 1, wherein the pump
housing has a cylindrical shape of which the outer peripheral
surface has a polygonal cross section, the second cover member has
a plate-like shape of which the outer peripheral surface has a
polygonal cross section, and each of the positioning retainers is a
surface defined by a side of the polygonal cross section.
11. The electric vacuum pump according to claim 1, wherein the case
is made of a metal material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Applications No.
2013-040766 filed Mar. 1, 2013 and No. 2013-177796 filed Aug. 29,
2013, the entire contents of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a vacuum pump for
generating negative pressure to be used in a brake booster of a
vehicle such as a car.
[0004] 2. Related Art
[0005] A brake device for car is provided with a brake booster for
amplifying a braking force by utilizing negative pressure in an
intake pipe ("intake-pipe negative pressure") of an engine. In
recent years, pumping loss is reduced in response to demands for
low-fuel consumption and thus the negative pressure in the intake
pipe tends to decrease. Furthermore, for a hybrid vehicle, an
electric vehicle, or a vehicle with an idling stop function, there
is a case where the intake-pipe negative pressure of an engine
could not be obtained.
[0006] Accordingly, the negative pressure to be supplied to a brake
booster is generated by use of an electric vacuum pump. In a
vehicle mounting a diesel engine that generates no intake-pipe
negative pressure, negative pressure is also generated by use of an
electric vacuum pump.
[0007] One example of such a vacuum pump is disclosed in, for
example, Patent Document 1. In this vane pump, a cam ring and a
bearing, which are internally mounted in a casing, are formed with
cutouts in alignment with each other on respective outer peripheral
surfaces and thus are positioned in place with respect to the
casing by a pin inserted in the cutouts. The casing is mounted
together with a front cover placed on one end side in a housing
placed on the other end side through a joint bolt.
RELATED ART DOCUMENTS
Patent Documents
[0008] Patent Document 1: JP-A-3(1991)-290083
SUMMARY OF INVENTION
Problems to be Solved by the Invention
[0009] However the vane pump disclosed in Patent Document 1 is
configured such that a screw hole for a bolt to integrally assemble
the casing and the housing is provided in an annular bracket of a
motor. A portion for positioning the cam ring and the baring with
respect to the casing and a portion through which the bolt is
formed to integrally assemble the casing and the housing are formed
in different positions so that they are displaced in a radial
direction of the vane pump. This causes an increase in cross
sectional area of the vane pump in the radial direction, resulting
in a large sized vane pump.
[0010] The present invention has been made to solve the above
problems and has a purpose to provide an electric vacuum pump
capable of achieving reduced size and improved accuracy of
assembling components to constitute a pump chamber.
Means of Solving the Problems
[0011] To achieve the above purpose, one aspect of the invention
provides an electric vacuum pump including: a case having internal
space; a motor part placed in the internal space of the case; and a
pump part placed in the internal space of the case and to be driven
in sync with the motor part, wherein the pump part includes: a
cylindrical pump housing; a first cover member placed in the pump
housing on one end side in a center axis direction of the pump
housing; a second cover member placed in the pump housing on the
other end in the center axis direction; a pump chamber formed by an
inner peripheral surface of the pump housing, the first cover
member, and the second cover member; and a rotor housed in the pump
chamber and including a plurality of vanes inserted therein, the
electric vacuum pump further includes a fastening member passed
through a through hole formed in the first cover member and being
fastened in a fastening hole formed in the case to fix the first
cover member to the case and the pump housing, the pump housing is
provided with a positioning retainer formed on an outer periphery
and the second cover member is provided with a positioning retainer
formed on an outer periphery, the case is provided with a
positioning protrusion formed to protrude inward from an inner
peripheral surface of the case, the positioning retainers are in
contact with the positioning protrusion to position the pump
housing and the second cover member with respect to the case, and
the fastening hole is formed in the positioning protrusion.
[0012] According to the above configuration, the first cover member
is fixed to the case and the pump housing by the fastening member.
The fastening hole in which the fastening member is to be fastened
is formed in the positioning protrusion formed on the inner
peripheral surface of the case. In this way, the positioning
protrusion and the fastening hole are formed in the same place in
the radial direction. Accordingly, the cross sectional area of the
electric vacuum pump in the radial direction is reduced and thus
the electric vacuum pump can be reduced in size. When the
positioning retainers are in contact with the positioning
protrusion, positioning the pump housing and the second cover
member with respect to the case, the pump housing and the second
cover member can be assembled with the case with high accuracy. In
this manner, the electric vacuum pump can achieve size reduction
and also improved assembling accuracy of the components to form the
pump chamber.
[0013] The pump housing and the second cover member are placed in
contact with the case so that the positioning retainers contact
with the positioning protrusion. This can enhance heat dissipation
property of the electric vacuum pump from the pump part to the
outside.
[0014] In the above configuration, preferably, the positioning
retainers are formed to respectively protrude from an outer
peripheral surface of the pump housing and an outer peripheral
surface of the second cover member toward the inner peripheral
surface of the case and include grooves engageable with the
positioning protrusion.
[0015] According to the above configuration, the grooves of the
positioning retainer is in contact engagement with the positioning
protrusion of the case, thereby enabling reliable positioning of
each of the pump housing and the second cover member with respect
to the case. This further improves the assembling accuracy of the
pump housing and the second cover member with respect to the
case.
[0016] In the above configuration, preferably, the case has an end
face on the one end side in the center axis direction of the pump
housing, the end face being located in the same position as an end
face of the first cover member on the other end side in the center
axis direction of the pump housing or located in a position closer
to the one end side than the end face of the first cover member on
the other end side.
[0017] According to the above configuration, a portion of the
positioning protrusion surrounding the fastening hole in the radial
direction can have sufficient thickness and also the outer
peripheral surface of the case and the outer peripheral surface of
the positioning protrusion can be made common. This enables further
reduction in the cross sectional area of the case in the radial
direction and thus further size reduction of the electric vacuum
pump.
[0018] In the above configuration, preferably, the pump part and
the inner peripheral surface of the case form therebetween a space
in an area excepting the positioning protrusion and the positioning
retainers.
[0019] According to the above configuration, the space is generated
around the pump part. Since the fastening hole is formed in the
positioning protrusion as above, the volume of the space can be
increased as large as possible. This can enhance the silencing
performance of the electric vacuum pump during operation.
[0020] Preferably, the above configuration further includes a
member placed in the space to produce at least one of a silencing
effect and a cooling effect.
[0021] According to the above configuration, the silencing
performance and the cooling performance of the electric vacuum pump
can be further enhanced. Since the member is set in the space
formed between the pump part and the inner peripheral surface of
the case, furthermore, assembling the member is easy.
[0022] In the above configuration, preferably, the case includes a
rib placed in the space and formed to protrude inward from the
inner peripheral surface of the case.
[0023] According to the above configuration, the case can have high
strength.
[0024] In the above configuration, preferably, the case is provided
with a plurality of the positioning protrusions and a plurality of
the fastening holes in two or more and odd-numbered pairs, and one
pair of the pairs of positioning protrusions and fastening holes is
placed in a position 180.degree. opposite to a center axis of the
inner peripheral surface of the pump housing with respect to a
rotation center axis of the rotor.
[0025] According to the above configuration, the electric vacuum
pump can be reduced in size more effectively.
[0026] In the above configuration, preferably, the first cover
member includes a suction inlet for sucking gas from outside into
the pump chamber and a discharge outlet for discharging gas from
the pump chamber to the outside, and the pump housing and the first
cover member are integrally formed.
[0027] The above configuration can provide improved positional
accuracy of the suction inlet for sucking gas from outside into the
pump chamber and the discharge outlet for discharging gas from the
pump chamber to the outside, thus increasing a pump efficiency of
the electric vacuum pump.
[0028] In the above configuration, preferably, a cover closing the
internal space of the case from a side of the pump part, and the
cover and the first cover member form therebetween a space.
[0029] According to the above configuration, the space is formed in
the cover member and thus the silencing performance of the electric
vacuum pump during operation can be enhanced.
[0030] In the above configuration, preferably, the pump housing has
a cylindrical shape of which the outer peripheral surface has a
polygonal cross section, the second cover member has a plate-like
shape of which the outer peripheral surface has a polygonal cross
section, and each of the positioning retainers is a surface defined
by a side of the polygonal cross section.
[0031] According to the above configuration, the surface defined by
one side of the polygonal shape of each of the pump housing and the
second cover member is placed in contact with the positioning
protrusion of the case, so that the pump housing and the second
cover member can be reliably positioned in place with respect to
the case. Accordingly, the assembling accuracy of the pump housing
and the second cover member with respect to the case can be further
improved.
[0032] In the above configuration, preferably, the case is made of
a metal material.
[0033] The above configuration allows the pump housing and the
second cover member to be press-fit in the metal case, so that the
accuracy for assembling the member to constitute the pump chamber
in the radial direction can be enhanced.
Effects of the Invention
[0034] The electric vacuum pump according to the invention can
achieve reduced size and improved accuracy for assembling
components to constitute a pump chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a schematic configuration view of a brake system
including an electric vacuum pump in an embodiment;
[0036] FIG. 2 is a block diagram showing a control system of the
brake system including the electric vacuum pump in the
embodiment;
[0037] FIG. 3 is a front view of the electric vacuum pump in the
embodiment;
[0038] FIG. 4 is a top view of the electric vacuum pump in the
embodiment;
[0039] FIG. 5 is a cross sectional view taken along a line A-A in
FIG. 3;
[0040] FIG. 6 is a cross sectional view taken along a line B-B in
FIG. 5;
[0041] FIG. 7 is a perspective exploded view of the electric vacuum
pump in the embodiment;
[0042] FIG. 8 is a top view of an upper-end cover member;
[0043] FIG. 9 is a top view of a pump housing;
[0044] FIG. 10 is a top view of a lower-end cover member;
[0045] FIG. 11 is a cross sectional view of a modified example,
corresponding FIG. 5;
[0046] FIG. 12 is one example of a cross sectional view taken along
a line C-C in FIG. 11;
[0047] FIG. 13 is another example of the cross sectional view taken
along the line C-C in FIG. 11;
[0048] FIG. 14 is a cross sectional view of another modified
example, corresponding to FIG. 5;
[0049] FIG. 15 is a cross sectional view of another modified
example, corresponding to FIG. 6;
[0050] FIG. 16 is a top view of a one-piece housing;
[0051] FIG. 17 is a cross sectional view of the one-piece housing
taken along a line D-D in FIG. 16;
[0052] FIG. 18 is a cross sectional view of an electric vacuum pump
of another modified example;
[0053] FIG. 19 is a top view of a lower-end cover member of the
modified example shown in FIG. 18; and
[0054] FIG. 20 is a cross sectional view of an electric vacuum pump
of a comparative example.
DESCRIPTION OF EMBODIMENTS
[0055] A detailed description of a preferred embodiment of an
electric vacuum pump embodying the present invention will now be
given referring to the accompanying drawings. In the present
embodiment, the electric vacuum pump of the invention applied to a
brake system will be explained.
[0056] This brake system is first explained referring to FIGS. 1
and 2. FIG. 1 is a schematic configuration view of the brake system
including the electric vacuum pump in the present embodiment. FIG.
2 is a block diagram showing a control system of the brake system
including the electric vacuum pump in the present embodiment.
[0057] A brake system 1 in the present embodiment includes, as
shown in FIGS. 1 and 2, a brake pedal 10, a brake booster 12, a
master cylinder 14, a negative pressure sensor 16, an electric
vacuum pump 18 (labeled "Electric VP" in the figure), a first check
valve 20, a second check valve 22, an ECU 24, an intake pipe
pressure detection unit 26, an engine stop determination unit 28,
and others.
[0058] The brake booster 12 is provided between the brake pedal 10
and the master cylinder 14 as shown in FIG. 1. This brake booster
12 generates an assist force at a predetermined boosting ratio to a
tread force on the brake pedal 10.
[0059] The brake booster 12 is internally partitioned by a
diaphragm (not illustrated) into a negative pressure chamber (not
shown) close to the master cylinder 14 and a transformer chamber
(not shown) allowing introduction of atmospheric air. The negative
pressure chamber of the brake booster 12 is connected to an intake
pipe 32 of an engine through a first passage L1. Specifically, the
first passage L1 is connected to the negative pressure chamber of
the brake booster 12 and the intake pipe 32. Accordingly, the
negative pressure chamber of the brake booster 12 is supplied with
negative pressure generated in the intake pipe 32 through the first
passage L1 according to an opening degree of a throttle valve 34
during driving of the engine.
[0060] The master cylinder 14 increases oil pressure of a brake
main body (not shown) by operation of the brake booster 12, thereby
generating a braking force in the brake main body. The negative
pressure sensor 16 detects the negative pressure in the negative
pressure chamber of the brake booster 12.
[0061] The electric vacuum pump 18 is connected to a second passage
L2 as shown in FIG. 1. Specifically, a suction port 141 of the
electric vacuum pump 18 is connected to the negative pressure
chamber of the brake booster 12 through the second passage L2 and
the first passage L1. It is to be noted that a discharge port 142
of the electric vacuum pump 18 is connected to the intake pipe 32
upstream of the throttle valve 34 and is open to the atmosphere.
Herein, the second passage L2 is a pathway for branching from the
first passage L1 at a position on the first passage L1 between the
first check valve 20 and the second check valve 22.
[0062] The electric vacuum pump 18 is further connected to the ECU
24 through a relay 36 as shown in FIG. 2. Driving of the electric
vacuum pump 18 is controlled by ON/OFF operation of the relay 36 by
the ECU 24.
[0063] The first check valve 20 is provided in the first passage L1
at a position between a branch point to the second passage L2 and
the brake booster 12 as shown in FIG. 1. The second check valve 22
is provided in the first passage L1 at a position closer to the
intake pipe 32 than the first check valve 20 and between the branch
point to the second passage L2 and the intake pipe 32. These first
check valve 20 and second check valve 22 are each configured to
open only when negative pressure on the side of the intake pipe 32
is higher than the negative pressure on the side of the negative
pressure chamber of the brake booster 12 and to permit a fluid to
flow only from the negative pressure chamber of the brake booster
12 to the intake pipe 32. In this manner, the brake system 1 can
encapsulate negative pressure in the negative pressure chamber of
the brake booster 12 by the first check valve 20 and the second
check valve 22.
[0064] The ECU 24 consists of for example a microcomputer and
includes a ROM that stores control programs, a rewritable RAM that
stores calculation results and others, a timer, a counter, an input
interface, and an output interface. To this ECU 24, as shown in
FIG. 2, there are connected the negative pressure sensor 16, the
electric vacuum pump 18, the intake pipe pressure detection unit
26, the engine stop determination unit 28, the relay 36, and
others.
[0065] Next, the electric vacuum pump 18 will be explained
referring to FIGS. 3 to 6. FIG. 3 is a front view of the electric
vacuum pump in the present embodiment. FIG. 4 is a top view of the
electric vacuum pump in the present embodiment. FIG. 5 is a cross
sectional view taken along a line A-A in FIG. 3. FIG. 6 is a cross
sectional view taken along a line B-B in FIG. 5.
[0066] The electric vacuum pump 18 has a cylindrical shape as shown
in FIGS. 3 and 4 and is provided with the suction port 141 and the
discharge port 142 at an upper end and a connector 118 at a lower
end. This electric vacuum pump 18 includes a motor part 110, a pump
part 120, a resin case 130, a resin upper cover 140, and a resin
lower cover 160. Further, as shown in FIG. 6, the case 130 contains
the internal space in which the motor part 110 and the pump part
120 are accommodated. The case 130 containing the motor part 110
and the pump part 120 is closed by the upper cover 140 and the
lower cover 160.
[0067] The motor part 110 includes an electric motor 112, a metal
motor case 114, a rotary shaft 116, and the connector 118. The
electric motor 112 is set in the motor case 114 and includes a
stator 112a and a rotor 112b. The stator 112a is fixed to the motor
case 114 so that the rotor 112b is rotatably placed inside the
stator 112a with a clearance therefrom.
[0068] The rotary shaft 116 is attached to this rotor 112b. The
connector 118 including terminals 118a for supplying electric power
to the electric motor 112 (the stator 112a) is provided on the
lower cover 160.
[0069] Accordingly, in the motor part 110, the electric motor 112
is driven by an external power supply connected through the
connector 118 to drive the rotary shaft 116 to rotate. The rotary
shaft 116 is rotatably supported by a bearing fixed to the motor
case 114.
[0070] The pump part 120 is constituted of a vane-type vacuum pump
and is placed above the motor part 110 in the case 130. The pump
part 120 will be driven in sync with the motor part 110. Herein,
the vane-type vacuum pump is configured such that a rotor having a
circular columnar shape placed in an eccentric state in a pump
chamber is formed with grooves, in which a plurality of vanes are
inserted to be movable in a rotor radial direction. When the rotor
rotates, the vanes are caused to protrude from the grooves by
centrifugal force and slide in contact with the inner peripheral
surface of the pump chamber, thereby maintaining hermetical sealing
between adjacent small chambers of the pump chamber. In association
therewith, the volume of each closed space or small chamber
partitioned by the vanes is increased or decreased, thereby causing
suction, compression, and discharge of air, so that negative
pressure is generated in the pump chamber.
[0071] To be concrete, the pump part 120 is provided with a pump
housing 121 having an inner peripheral surface 121a of a nearly
cylindrical shape. The inner peripheral surface 121a of a nearly
cylindrical shape represents that the cross section of the pump
housing is defined in a circular shape surrounded by a curved line
without being limited to a perfect circular or elliptic shape. Both
ends of the pump housing 121 are closed by an upper-end cover
member 122a (see FIG. 7) having a nearly circular disc shape and a
lower-end cover member 122b (see FIG. 7) having a nearly circular
disc shape formed with a hole 122bb at almost the center. The inner
peripheral surface 121a of the pump housing 121, the upper-end
cover member 122a, and the lower-end cover member 122b form a pump
chamber 123. The pump housing 121 is fixed to the case 130. It is
to be noted that the upper-end cover member 122a is one example of
a "first cover member" of the invention and the lower-end cover
member 122b is one example of a "second cover member" of the
invention.
[0072] In the pump chamber 123, a circular columnar rotor 124 is
housed to be rotatable about the axis eccentric to the center axis
of the pump chamber 123. This rotor 124 is coupled to the rotary
shaft 116 of the electric motor 112. Accordingly, the rotor 124 is
rotated in sync with rotary driving of the electric motor 112 via
the rotary shaft 116.
[0073] The rotor 124 has a plurality of vane grooves. In the vane
groove, vanes 125 each formed in a flat plate shape are slidably
engaged to be radially movable in and out. A radially outer end of
each vane 125 slides in contact with the inner peripheral surface
121a of the pump housing 121 by centrifugal force imparted to the
vanes 125 during rotation of the rotor 124. Upper and lower end
faces of the vanes 125 are in contact with the cover members 122a
and 122b respectively. Thus, the vanes 125 partition the pump
chamber 123 into a plurality of small chambers or spaces.
[0074] The pump chamber 123 communicates with the outside through a
suction inlet 126 and a discharge outlet 127. The suction inlet 126
is provided in the upper-end cover member 122a to communicate with
the pump chamber 123. The suction inlet 126 is hermetically
connected to an inlet pipe 141a continuous with the suction port
141 to suck air from pump outside into the pump chamber 123.
Similarly, the discharge outlet 127 is also provided in the
upper-end cover member 122a to communicate with the pump chamber
123. Exhaust air ejected from the discharge outlet 127 is
discharged to the pump outside through the discharge port 142.
[0075] The upper cover 140 is a resin member closing an upper open
end of the case 130 accommodating the motor part 110 and the pump
part 120. The upper cover 140 is one example of a "cover" of the
invention. Specifically, the upper cover 140 closes the case 130
from the pump part side (from above in FIG. 6).
[0076] This upper cover 140 is provided with the suction port 141
to suck air in the pump part 120 from the pump outside, the inlet
pipe 141a connected to the suction port 141, a silencer part 143
formed by the space communicating with the discharge outlet 127 of
the pump part 120, the discharge port 142 to discharge exhaust air
discharged or ejected from the pump part 120 to the pump outside,
and a throat part 142a provided in the discharge port 142.
[0077] The silencer part 143 is formed by the internal space of the
upper cover 140. Specifically, the silencer part 143 is defined by
the space between the upper cover 140 and the upper-end cover
member 122a. The throat part 142a is formed in the discharge port
142. Thus, exhaust air discharged or ejected from the discharge
outlet 127 of the pump part 120 passes through the silencer part
143 and then is discharged to the pump outside through the throat
part 142a. Consequently, the exhaust air can be repeatedly exposed
to loads, so that pump operation sound or noise can be reduced to a
minimum. In this manner, the electric vacuum pump 18 can be
effectively provided with the sound-reducing (silencing) measure
with a very simple structure.
[0078] The shape of the throat part 142a is not particularly
limited and may be a shape that an entire discharge port is
narrowed to form a throat as shown in FIG. 6 or a shape that part
of the discharge port is narrowed or constricted.
[0079] The lower cover 160 is a resin member closing a lower open
end of the case 130 accommodating the motor part 110 and the pump
part 120. The lower cover 160 closes the case 130 from the motor
part side (from below in FIG. 6).
[0080] In the electric vacuum pump 18 configured as above, when the
electric motor 112 is driven to rotate upon receipt of power from
an external source, the rotor 124 is rotated in synchronization
therewith. Then, the vanes 125 slide along the vane grooves by
centrifugal force, causing the end faces of the vanes 125 to
contact with the inner peripheral surface 121a of the pump housing
121. While keeping such a contact state, the vanes 125 are rotated
along the inner peripheral surface 121a of the pump housing 121.
This rotation of the rotor 124 causes the volume of each small
chamber of the pump chamber 123 to expand or contract, thereby
sucking air into the pump chamber 123 through the suction inlet 126
and ejecting air from the pump chamber 123 through the discharge
outlet 127. This operation generates negative pressure in the pump
chamber 123.
[0081] Specifically, in the brake system 1, when the relay 36 is
turned on based on a drive start signal from the ECU 24, the
electric vacuum pump 18 starts operating, thereby supplying
negative pressure to the negative pressure chamber of the brake
booster 12 through the suction port 141, the second passage L2 and
the first passage L1. Furthermore, when the relay 36 is turned off
based on a drive stop signal from the ECU 24, the electric vacuum
pump 18 stops operating, thereby stopping supplying negative
pressure to the negative pressure chamber of the brake booster 12
through the suction port 141, the second passage L2 and the first
passage L1.
[0082] In the brake system 1, in a case where the engine is running
and negative pressure is generated in the intake pipe, the negative
pressure in the intake pipe 32 is supplied to the negative pressure
chamber of the brake booster 12 through the first passage L1 to
regulate the negative pressure in the negative pressure chamber of
the brake booster 12. In a case where the engine is stopped or in a
case where the ECU 24 determines that the negative pressure is
insufficient, the ECU 24 turns on the relay 36, thereby driving the
electric vacuum pump 18 to supply the negative pressure to the
negative pressure chamber of the brake booster 12 through the
second passage L2 and the first passage L1. Thus, the negative
pressure in the negative pressure chamber of the brake booster 12
can be regulated.
[0083] Herein, an explanation is given to positioning of the pump
housing 121 and the lower-end cover member 122b with respect to the
case 130 and fixing of the upper-end cover member 122a to the pump
housing 121 and the case 130.
[0084] As shown in FIGS. 5 and 6, the pump part 120 includes the
pump housing 121, the upper-end cover member 122a, the lower-end
cover member 122b, the pump chamber 123, the rotor 124, and others.
The upper-end cover member 122a is placed on an upper end of the
pump housing 121 in a center axis direction of the pump housing
121. The lower-end cover member 122b is placed on a lower end of
the pump housing 121 in the center axis direction of the pump
housing 121. The pump chamber 123 is defined by the inner
peripheral surface 121a of the pump housing 121, the upper-end
cover member 122a, and the lower-end cover member 122b.
[0085] In the present embodiment, as shown in FIG. 7, screws 170
are passed through through holes 172 of the upper-end cover member
122a and fastened in screw holes 174 formed in the case 130 to
thereby fix the upper-end cover member 122a to the case 130 and the
pump housing 121. Accordingly, the pump housing 121 and the
lower-end cover member 122b are simultaneously fixed to the case
130. The screws 170 are one example of a "fastening member" of the
invention and the screw holes 174 are one example of a "fastening
hole" of the invention. In FIG. 7, the rotor 124 is omitted for
convenience of explanation.
[0086] The case 130 is provided, on its inner peripheral surface
130a, with positioning protrusions 176 formed radially protruding
inward in the case 130. Each of the positioning protrusions 176 is
designed so that its outer peripheral surface 176a has a nearly
cylindrical shape. The positioning protrusions 176 are arranged
outside the pump chamber 123 in the radial direction of the case
130. In an example shown in FIG. 5 and other figures, the case 130
includes three positioning protrusions 176. Having the nearly
cylindrical shape as each outer peripheral surface 176a represents
that the cross section of each positioning protrusion 176 is not
limited to a perfect circle or an ellipse, but is defined as a
circular shape surrounded by a curved line.
[0087] As shown in FIGS. 5 to 7 and 9, the pump housing 121 is
provided with positioning retainers 178 formed on the outer
periphery. Each of the positioning retainers 178 is formed to
protrude from an outer peripheral surface 121b of the pump housing
121 toward the inner peripheral surface 130a of the case 130 and is
provided with a groove 180 engageable with the corresponding
positioning protrusion 176. In the example shown in FIG. 5 and
others, the pump housing 121 includes three positioning retainers
178. As shown in FIG. 5, the grooves 180 of the positioning
retainers 178 are in contact engagement with the positioning
protrusions 176, so that the pump housing 121 is positioned in
place with respect to the case 130.
[0088] As shown in FIGS. 6, 7, and 10, the lower-end cover member
122b includes positioning retainers 182 formed on the outer
periphery. Each of the positioning retainers 182 is formed to
protrude from an outer peripheral surface 122ba of the lower-end
cover member 122b toward the inner peripheral surface 130a of the
case 130 and is provided with a groove 184 engageable with the
corresponding positioning protrusion 176. In the example shown in
FIG. 10 and others, the lower-end cover member 122b includes three
positioning retainers 182. The grooves 184 of the positioning
retainers 182 are in contact engagement with the positioning
protrusions 176, so that the lower-end cover member 122b is
positioned in place with respect to the case 130.
[0089] As shown in FIGS. 6 to 8, the upper-end cover member 122a
includes screw stoppers 185 formed on the outer periphery. Each of
the screw stoppers 185 is formed to protrude from an outer
peripheral surface 122aa of the upper-end cover member 122a toward
the inner peripheral surface 130a of the case 130 and is provided
with the through holes 172 through which the screws 170 are passed.
In the example shown in FIG. 8 and others, the upper-end cover
member 122a includes three screw stoppers 185. Since the screws 170
are passed through the through holes 172 and are fastened in the
screw holes 174, the upper-end cover member 122a is fixed to the
case 130. Accordingly, the upper-end cover member 122a is
positioned with respect to the case 130.
[0090] In the present embodiment, the screw holes 174 are formed
one each in the positioning protrusions 176. In this way, the screw
holes 174 and the positioning protrusions 176 are arranged in the
same positions in the radial direction of the case 130. Thus, the
cross sectional area of the electric vacuum pump 18 in the radial
direction is small and the electric vacuum pump 18 can be reduced
in size.
[0091] In the present embodiment, as shown in FIG. 6, an end face
130b of the case 130 on an upper side (on one end side) in the
axial direction of the electric vacuum pump 18, i.e., in the axial
direction of the pump housing 121 (in an up and down direction in
FIG. 6) is located in a position above an end face 122ab of the
upper-end cover member 122a on a lower side (on the other end side)
in the axial direction of the pump housing 121. Specifically, in
the axial direction of the pump housing 121, the upper end face
130b of the case 130 is located above the upper end faces 176b of
the positioning protrusions 176.
[0092] In the above manner, while each portion forming the
positioning protrusions 176 surrounding the corresponding screw
holes 174 in the radial direction is thick enough to resist against
fastening forces of the screws 170, an outer peripheral surface
130c of the case 130 and outer peripheral surfaces 176a of the
positioning protrusions 176 are made common. This can achieve
reduction of the cross sectional area of the case 130 in the radial
direction and further size reduction of the electric vacuum pump
18.
[0093] The inner peripheral surface 130a of the case 130 is located
outside the outer peripheral surface 122aa of the upper-end cover
member 122a, so that the upper-end cover member 122a is assembled
with the pump housing 121 by being guided by the inner peripheral
surface 130a of the case 130. Thus, the assembling accuracy of the
upper-end cover member 122a (positional accuracy of the upper-end
cover member 122a to be assembled) in the radial direction (a right
and left direction in FIG. 6) of the pump housing 121 can be
enhanced.
[0094] In the axial direction of the electric vacuum pump 18, the
upper end face 130b of the case 130 may be located on the same
level or position as the lower end face 122ab of the upper-end
cover member 122a.
[0095] Silencer parts 186 are formed by space or cavity between the
pump part 120 and the inner peripheral surface 130a of the case
130, in an area excepting the positioning protrusions 176,
positioning retainers 178, and positioning retainers 182. Each
silencer part 186 is communicated with the aforementioned silencer
part 143. In the present embodiment in which the screw holes 174
are formed in the positioning protrusions 176, the width .delta.
(see FIG. 5) of each of the positioning retainers 178 and 182 in
the circumferential direction of the case 130 can be reduced to the
minimum. This increases the volume of the space, i.e., the silencer
parts 186, contributing to high silencing performance during
operation of the electric vacuum pump 18. For instance, the width 6
in the present embodiment can be reduced as compared with the width
60 of each positioning retainer 202 of an electric vacuum pump 200
in a comparative example shown in FIG. 20. The electric vacuum pump
200 is configured such that positioning protrusions 204 and screw
holes 206 are formed in different positions with displacement in
the circumferential direction of a case 208.
[0096] In a modified example, as shown in FIGS. 11 and 12, members
194 capable of producing at least one of a silencing effect and a
cooling effect may be placed in the silencer parts 186. For
example, the members 194 are resin filters in the present
embodiment. In this manner, since the filters 194 are placed in the
silencer parts 186, the silencing performance and the cooling
performance of the electric vacuum pump 18 can be further enhanced.
Further, since the filters 194 are simply set in the space forming
the silencer parts 186, mounting of the filters 194 is easy. The
filters 194 may also be filled throughout the entire silencer parts
186. In another modified example, as shown in FIG. 13, the filters
194 may be placed not only in the silencer parts 186 but also in
the silencer part 143. FIGS. 12 and 13 illustrate one examples of a
cross section taken in a line C-C in FIG. 11, showing only the pump
part 120 and its surroundings.
[0097] As shown in FIG. 5, the positioning protrusions 176 and the
screw holes 174 are formed in three pairs so that one of the pairs
is arranged in a position 180-degree opposite to the center axis Sp
of the inner peripheral surface 121a of the pump housing 121 with
respect to the rotation center axis Sr of the rotor 124. This can
achieve size reduction of the electric vacuum pump 18. The
positioning protrusions 176 and the screw holes 174 may also be
formed in two or more and odd-numbered pairs, instead of three
pairs.
[0098] As another modified example, as shown in FIG. 14, the case
130 may be provided with ribs 196 on the inner peripheral surface
130a. Each of the ribs 196 is formed in a cylindrical shape as with
the positioning protrusions 176 so that the direction of the center
axis of each rib 196 is the same as the axial direction of the
electric vacuum pump 18. The ribs 196 are arranged in the silencer
parts 186. In the example shown in FIG. 14, two ribs 196 are
provided. However, the number of ribs 196 is not particularly
limited thereto. In this manner, the case 130 including the ribs
196 formed on the inner peripheral surface 130a can provide
enhanced strength. The ribs 196 may be in contact with the outer
peripheral surface 121b of the pump housing 121 and the outer
peripheral surface 122ba of the lower-end cover member 122b.
[0099] As another modified example, the case 130 may be made of
metal. As shown in FIG. 15, accordingly, the pump housing 121 and
the lower-end cover member 122b can be press-fitted in the case
130. Thus, the pump housing 121 and the lower-end cover member 122b
can be assembled with high accuracy in the radial direction of the
pump housing 121. FIG. 15 shows a press-fit portion a of the pump
housing 121 and the lower-end cover member 122b that are press
fitted in the case 130. In this modified example, the case 130 also
serves as the case 114.
[0100] The electric vacuum pump 18 in the present embodiment
explained in detail above includes the case 130 having the internal
space, the motor part 110 placed in the internal space of the case
130, and the pump part 120 placed in the internal space of the case
130 and to be driven in sync with the motor part 110. The pump part
120 includes the cylindrical pump housing 121, the upper-end cover
member 122a placed on the upper end of the pump housing 121 in the
center axis direction thereof, the lower-end cover member 122b
placed on the lower end of the pump housing 121 in the center axis
direction thereof, the pump chamber 123 formed by the inner
peripheral surface 121a of the pump housing 121, the upper-end
cover member 122a, and the lower-end cover member 122b, and the
rotor 124 which is set in the pump chamber 123 and in which the
plurality of vanes 125 are inserted. The screws 170 are passed
through the through holes 172 of the upper-end cover member 122a
and fastened in the screw holes 174 of the case 130, thereby fixing
the upper-end cover member 122a to the case 130 and the pump
housing 121. The pump housing 121 includes the positioning
retainers 178 formed on the outer periphery of the pump housing
121. The lower-end cover member 122b includes the positioning
retainers 182 formed on the outer periphery of the lower-end cover
member 122b. The case 130 includes the positioning protrusions 176
formed to protrude inward in the case 130 from the inner peripheral
surface 130a of the case 130. Since the positioning retainers 178
and the positioning retainers 182 are in contact with the
positioning protrusions 176, the pump housing 121 and the lower-end
cover member 122b are positioned in place with respect to the case
130. The positioning protrusions 176 are formed with the screw
holes 174.
[0101] As above, the screw holes 174 are formed in the positioning
protrusions 176 of the case 130. The positioning protrusions 176
and the corresponding screw holes 174 are thus formed in the same
places in the radial direction, so that the electric vacuum pump 18
can have a reduced cross sectional area in the radial direction and
thus can have a reduced size. Since the positioning retainers 178
and the positioning retainers 182 are in contact with the
positioning protrusions 176, thereby positioning the pump housing
121 and the lower-end cover member 122b with respect to the case
130, the assembling accuracy of the pump housing 121 and the
lower-end cover member 122b with respect to the case 130 can be
enhanced. In the above manner, the electric vacuum pump 18 can
achieve size reduction and improved assembling accuracy of the
components to form the pump chamber 123.
[0102] The pump housing 121 and the lower-end cover member 122b are
in contact with the case 130 in such a manner that the positioning
retainers 178 and the positioning retainers 182 contact with the
positioning protrusions 176. This can improve heat dissipation
performance of the electric vacuum pump 18 from the pump part 120
to the outside.
[0103] The positioning retainers 178 and the positioning retainers
182 are respectively formed to protrude from the outer peripheral
surface 121b of the pump housing 121 and the outer peripheral
surface 122ba of the lower-end cover member 122b toward the inner
peripheral surface 130a of the case 130 and also respectively
include the grooves 180 and the grooves 184 engageable with the
positioning protrusions 176. Accordingly, the grooves 180 and the
grooves 184 are in contact engagement with the positioning
protrusions 176, thereby ensuring positioning of the pump housing
121 and the lower-end cover member 122b with respect to the case
130. Therefore, the assembling accuracy of the pump housing 121 and
the lower-end cover member 122b with respect to the case 130 can be
further improved.
[0104] In the center axis direction of the pump housing 121, the
upper end face 130b of the case 130 is located on the same level or
position as the lower end face 122ab of the upper-end cover member
122a or located above the lower end face 122ab of the upper-end
cover member 122a. Accordingly, while ensuring the sufficient
thickness of the portion of each positioning protrusion 176
surrounding the screw hole 174 in the radial direction, the outer
peripheral surface 130c of the case 130 and the outer peripheral
surface 176a of each positioning protrusion 176 are made common.
This can achieve further reduction of the cross sectional area of
the case 130 in the radial direction and thus further size
reduction of the electric vacuum pump 18.
[0105] The electric vacuum pump 18 is provided with the silencer
parts 186 between the pump part 120 and the inner peripheral
surface 130a of the case 130, in the area excepting the positioning
protrusions 176 and the positioning retainers 178 and 182. Thus,
the silencer parts 186 are formed around the pump part 120. Since
the positioning protrusions 176 are formed with the screw holes 174
as above, the volume of the silencer parts 186 can be increased as
much as possible. This can enhance the silencing performance of the
electric vacuum pump 18 during operation.
[0106] In the silencer parts 186, there may be placed the filters
194 that exert at least one of the silencing effect and the cooling
effect. Accordingly, the silencing performance and the cooling
performance of the electric vacuum pump 18 can be further improved.
The filters 194 are simply set in the silencer parts 186 defined by
the pump part 120 and the inner peripheral surface 130a of the case
130, so that assembling the filters 194 are easy.
[0107] The electric vacuum pump 18 may further include the ribs 196
formed in the silencer parts 186 to protrude radially inward from
the inner peripheral surface 130a of the case 130. This can enhance
the strength of the case 130.
[0108] The pairs of the positioning protrusions 176 and the screw
holes 174 are formed as two or more and odd-numbered pairs so that
one pair of the pairs of the positioning protrusions 176 and the
screw holes 174 is placed in a position 180.degree. opposite to the
center axis Sp of the inner peripheral surface 121a of the pump
housing 121 with respect to the rotation center axis Sr of the
rotor 124. This can effectively achieve size reduction of the
electric vacuum pump 18.
[0109] The electric vacuum pump 18 further includes the upper cover
140 that closes the internal space of the case 130 from the side of
the pump part 120. Between the upper cover 140 and the upper-end
cover member 122a, the silencer part 143 is formed. Since the space
is thus generated in the upper cover 140, the electric vacuum pump
18 can provide improved silencing performance during operation.
[0110] In a case where the case 130 is made of metal, the pump
housing 121 and the lower-end cover member 122b can be press-fitted
in the metal case 130. Thus, the components to form the pump
chamber 123 can be assembled with high accuracy in the radial
direction of the pump housing 121.
[0111] A conceivable modified example is shown in FIGS. 16 and 17.
In this modified example shown in FIGS. 16 and 17, a one-piece
housing 188 is configured to include the pump housing 121 and the
upper-end cover member 122a integrally formed. This can enhance the
positional accuracy of the suction inlet 126 and the discharge
outlet 127 and improve the pump efficiency of the electric vacuum
pump 18. As still another modified example, the pump housing 121
and the lower-end cover member 122b may be formed integrally.
[0112] Further, a modified example shown in FIGS. 18 and 19 is also
conceived. As shown in FIG. 18, the pump housing 121 is formed in a
rectangular cylindrical shape of which the outer peripheral surface
has a rectangular cross section (defined by four sides). As shown
in FIG. 19, the lower-end cover member 122b is formed in a
rectangular plate like shape of which the outer peripheral surface
has a rectangular cross section (defined by four sides). This cover
member 122b is formed with a hole at the center. Positioning
retainers 190 of the pump housing 121 and positioning retainers 192
of the lower-end cover member 122b correspond to surfaces defined
by the four sides. Accordingly, the positioning retainers 190 and
the positioning retainers 192 are respectively in contact with the
positioning protrusions 176, ensuring positioning of each of the
pump housing 121 and the lower-end cover member 122b with respect
to the case 130. Therefore, the pump housing 121 and the lower-end
cover member 122b can be assembled to the case 130 with high
accuracy. It is to be noted that the outer shape of each of the
pump housing 121 and the lower-end cover member 122b may also be
formed in any polygonal shape other than the rectangular shape.
[0113] The aforementioned embodiment and examples are mere examples
and do not limit the invention. The present invention may be
embodied in other specific forms without departing from the
essential characteristics thereof.
TABLE-US-00001 Reference Sings List 1 Brake system 10 Brake pedal
12 Brake booster 14 Master cylinder 16 Negative pressure sensor 18
Electric vacuum pump 20 First check valve 22 Second check valve 24
ECU 32 Intake pipe 34 Throttle valve 110 Motor part 112 Electric
motor 116 Rotary shaft 118 Connector 120 Pump part 121 Pump housing
121a Inner peripheral surface 121b Outer peripheral surface 122a
Upper-end cover member 122aa Outer peripheral surface 122ab End
face 122b Lower-end cover member 122ba Outer peripheral surface
122bb Hole 123 Pump chamber 124 Rotor 125 Vane 126 Suction inlet
127 Discharge outlet 130 Case 130a Inner peripheral surface 130b
End face 130c Outer peripheral surface 140 Upper cover 141 Suction
port 142 Discharge port 143 Silencer part 160 Lower cover 170 Screw
172 Through hole 174 Screw hole 176 Positioning protrusion 176a
Outer peripheral surface 176b End face 178 Positioning retainer (of
Pump housing) 180 Groove (of Pump housing) 182 Positioning retainer
(of Lower-end cover member) 184 Groove (of Lower-end cover member)
185 Screw stopper (of Upper-end cover member) 186 Silencer part 188
One-piece housing 190 Positioning retainer (of Pump housing) 192
Positioning retainer (of Lower-end cover member) 194 Filter 196 Rib
L1 First passage L2 Second passage Sr Rotation center axis (of
Rotor) Sp Center axis of (Inner peripheral surface of pump housing)
.alpha. Press-fit portion
* * * * *