U.S. patent application number 14/063539 was filed with the patent office on 2014-05-01 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 | 20140119957 14/063539 |
Document ID | / |
Family ID | 50479924 |
Filed Date | 2014-05-01 |
United States Patent
Application |
20140119957 |
Kind Code |
A1 |
YAMANAKA; Shota ; et
al. |
May 1, 2014 |
ELECTRIC VACUUM PUMP
Abstract
An electric vacuum pump includes: a motor part and a pump part
placed in a case, and a cover member closing the case from a pump
part side. The cover member includes: a suction port for sucking a
fluid from pump outside into the pump part; a silencer part
including a space part communicating with a discharge outlet of the
pump part; and a discharge port for discharging a fluid ejected
from the pump part to pump outside. The suction port has an end
portion placed in sealingly contact with the pump part to
hermetically communicate with a suction inlet of the pump part. The
discharge port is formed with a throat part.
Inventors: |
YAMANAKA; Shota;
(Hekinan-shi, JP) ; MAKINO; Katsuhiko; (Chita-gun,
JP) ; SUGIMOTO; Atsushi; (Obu-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: |
50479924 |
Appl. No.: |
14/063539 |
Filed: |
October 25, 2013 |
Current U.S.
Class: |
417/312 |
Current CPC
Class: |
F04C 18/344 20130101;
F04C 25/02 20130101; F04C 29/063 20130101; F04B 17/03 20130101;
F04C 29/066 20130101 |
Class at
Publication: |
417/312 |
International
Class: |
F04B 17/03 20060101
F04B017/03 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2012 |
JP |
2012-236367 |
Claims
1. An electric vacuum pump including: a resin case having internal
space; a motor part placed in the internal space of the case, a
pump part placed in the internal space of the case and arranged to
drive in sync with the motor part, and a cover member closing the
internal space of the case from a pump part side, wherein the cover
member includes: a suction port for sucking a fluid from outside of
the pump into the pump part; a silencer part including a space part
communicating with a discharge outlet of the pump part; and a
discharge port for discharging a fluid ejected from the pump part
to outside of the pump, the suction port has an end placed in
sealingly contact with the pump part to hermetically communicate
with a suction inlet of the pump part, and the discharge port is
formed with a throat part.
2. The electric vacuum pump according to claim 1, wherein the
suction port and the discharge port are arranged in a project plane
of the electric vacuum pump in an axial direction of the electric
vacuum pump.
3. The electric vacuum pump according to claim 1, wherein the cover
member is made of resin by integral molding.
4. The electric vacuum pump according to claim 1, wherein the
suction port, the discharge port, and the throat part are made
together with the cover member by integral molding.
5. The electric vacuum pump according to claim 1, wherein the
suction port and the discharge port are placed on one end in an
axial direction of the electric vacuum pump so that open ends of
the suction port and the discharge port face in the same direction.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No. 2012-236367
filed on Oct. 26, 2012, 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 motorcar.
[0004] 2. Related Art
[0005] A brake device for vehicle 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 as a vacuum pump is disclosed in for
example Patent Document 1. This pump includes a case having an
internal space, a cylindrical moving member placed to be
eccentrically movable within the internal space, a cover placed in
the case to close the internal space at one end thereof, and a
deformable member fixed to the case and the moving member so as to
be deformed in association with eccentric movement of the moving
member. The cover has two ports for fluid. The deformable member
generates a pump space around the moving member so that the volume
of the pump space varies with the eccentric movement of the moving
member.
RELATED ART DOCUMENTS
Patent Documents
[0008] Patent Document 1: JP 9(1997)-296784A
SUMMARY OF INVENTION
Problems to be Solved by the Invention
[0009] However, the pump disclosed in Patent Document 1 does not
include a silencing function and causes large operation sound. In
particular, in a case where this pump is used in a brake system of
a vehicle such as a motorcar, it is necessary to extremely reduce
the operation sound. It is further desired to improve mountability
and installability on vehicles.
[0010] The present invention has been made to solve the above
problems and has a purpose to provide an electric vacuum pump with
sound-reducing (anti-noise) measure by a simple structure to
minimize operation sound or noise.
Means of Solving the Problems
[0011] To achieve the above purpose, one aspect of the invention
provides an electric vacuum pump including: a resin case having
internal space; a motor part placed in the internal space of the
case, a pump part placed in the internal space of the case and
arranged to drive in sync with the motor part, and a cover member
closing the internal space of the case from a pump part side,
wherein the cover member includes: a suction port for sucking a
fluid from outside of the pump into the pump part; a silencer part
including a space part communicating with a discharge outlet of the
pump part; and a discharge port for discharging a fluid ejected
from the pump part to outside of the pump, the suction port has an
end placed in sealingly contact with the pump part to hermetically
communicate with a suction inlet of the pump part, and the
discharge port is formed with a throat part.
Effects of the Invention
[0012] The electric vacuum pump of the invention, as explained
above can be provided with sound-reducing measure by a simple
structure and minimize operation sound or noise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic configuration view of a brake system
including an electric vacuum pump in an embodiment;
[0014] FIG. 2 is a block diagram showing a control system of the
brake system including the electric vacuum pump in the
embodiment;
[0015] FIG. 3 is a front view of the electric vacuum pump in the
embodiment;
[0016] FIG. 4 is a top view of the electric vacuum pump in the
embodiment;
[0017] FIG. 5 is a cross sectional view taken along a line A-A in
FIG. 4; and
[0018] FIG. 6 is a view showing a modified example of an electric
vacuum pump.
DESCRIPTION OF EMBODIMENTS
[0019] 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. The present
embodiment shows a case where the electric vacuum pump according to
the invention is applied to a brake system.
[0020] Thus, the brake system is firstly explained referring to
FIGS. 1 and 2. FIG. 1 is a schematic configuration view of the
brake system including the 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.
[0021] 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, and an engine stop determination unit
28, and others.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] The electric vacuum pump 18 is connected to the 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.
[0026] Furthermore, the electric vacuum pump 18 is connected to the
ECU 24 through a motor part 110 (electric motor 112) and 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.
[0027] 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. 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.
[0028] 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.
[0029] Herein, the electric vacuum pump 18 will be explained
referring to FIGS. 3 to 5. 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. 4.
[0030] 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 the 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. 5, the motor part
110 and the pump part 120 are housed in the case 130. 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.
[0031] 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 housed 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.
[0032] 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. 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.
[0033] The pump part 120 is constituted of a vane-type vacuum pump
and is placed above the motor part 110 in the case 130. 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.
[0034] To be concrete, the pump part 120 is provided with a housing
121 having an inner peripheral surface of a nearly cylindrical
shape. The inner peripheral surface of a nearly cylindrical shape
represents that the cross section of the 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 housing 121
are closed by circular cover members 122a and 122b, so that a pump
chamber 123 is formed by the inner peripheral surface of the
housing 121 and the cover members 122a and 122b. The housing 121 is
fixed to the case 130.
[0035] 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.
[0036] The rotor 124 has a plurality of vane grooves formed
radially extending from the axis in a radial direction. In the vane
groove, vanes 125 each formed in a flat plate shape are slidably
engaged to be movable in and out in the radial direction of the
circular columnar rotor 124. Those vanes 125 are arranged radially
and spaced circumferentially at equal intervals. A radially outer
end of each vane 125 slides in contact with the inner peripheral
surface of the 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.
[0037] 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 cover member 122a and communicated with the pump
chamber 123. The suction inlet 126 is hermetically closed by an end
of the suction port 141 sealingly connected to the cover member
122a to suck air from pump outside (the outside of the electric
vacuum pump 18) into the pump chamber 123. Similarly, the discharge
outlet 127 is also provided in the cover member 122a and
communicated with the pump chamber 123. Exhaust air ejected from
the discharge outlet 127 is discharged to the pump outside through
the discharge port 142.
[0038] The upper cover 140 is a resin member closing an upper open
end of the case 130 that houses the motor part 110 and the pump
part 120. The upper cover 140 is one example of a "cover member" of
the invention. Specifically, the upper cover 140 closes the case
130 from the pump part side (from above in FIG. 5).
[0039] This upper cover 140 is provided with the suction port 141
to suck air in the pump part 120 from the pump outside, an inlet
pipe 141a constituting part of the suction port 141, a silencer
part 143 including a space or cavity 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. Those suction port 141, inlet pipe 141a,
discharge port 142, and throat part 142a are made together with the
upper cover 140 by integral molding. Accordingly, joining of the
upper cover 140 with the case 130 housing the motor part 110 can be
made by welding without using screws or the like. In the present
embodiment, outer circumferential end faces of the upper cover 140
and the case 130 are joined to each other by ultrasonic welding.
This can result in a reduction in number of components of the
electric vacuum pump 18 and an increase in productivity thereof,
leading to cost reduction.
[0040] The silencer part 143 is formed by the internal space of the
upper cover 140. 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, flows through the throat part 142a, and then is
discharged to the pump outside. Thus, 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 measure
by a very simple structure.
[0041] The shape of the throat part 142a is not particularly
limited to the above. It may be a shape that an entire discharge
port is narrowed to form a throat as shown in FIG. 5 or a shape
that part of the discharge port is narrowed or constricted.
[0042] Furthermore, the suction port 141 and the discharge port 142
provided in the upper cover 140 are located within a project plane
of the electric vacuum pump 18 with respect to the pump axial
direction (longitudinal direction) (see FIG. 4). In other words,
the suction port 141 and the discharge port 142 are arranged so as
not to project outward from the outer diameter of the electric
vacuum pump 18. Accordingly, when the electric vacuum pump 18 is to
be mounted on a vehicle, the suction port 141 and the discharge
port 142 will not interfere with other components or parts,
resulting in improved mountability. An orientation of the electric
vacuum pump 18 to be mounted on a vehicle is not particularly
limited.
[0043] Moreover, the suction port 141 and the discharge port 142
are arranged on an upper end of the upper cover 140 (one end of the
vacuum pump in the axial direction) so that their open ends face in
the same direction (on the near side of a drawing sheet of FIG. 3).
This can facilitate a piping work in mounting the electric vacuum
pump 18 on a vehicle and thus improve installability.
[0044] The lower cover 160 is a resin member closing a lower open
end of the case 130 that houses 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. 5).
[0045] This lower cover 160 is provided, by integral molding, with
the connector 118 including the terminals 118a extending from the
motor part 110.
[0046] Accordingly, joining of the lower cover 160 with the case
130 housing the motor part 110 can be made by welding without using
screws. In the present embodiment, outer circumferential end faces
of the lower cover 160 and the case 130 are joined to each other by
ultrasonic welding. This can result in a reduction in number of
components of the electric vacuum pump 18 and an increase in
productivity thereof, leading to cost reduction.
[0047] The connector 118 provided in the lower cover 160 is
arranged to face in the same direction as the open ends of the
suction port 141 and the discharge port 142. This can facilitate an
electric wiring work in mounting the electric vacuum pump 18 on a
vehicle and thus improve installability.
[0048] 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 of the housing 121. While
keeping such a contact state, the vanes 125 are rotated along the
inner peripheral surface of the 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.
[0049] 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.
[0050] 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 and 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.
[0051] According to the electric vacuum pump 18 in the present
embodiment as explained in detail above, the sound-reducing measure
is achieved by a very simple configuration that the suction port
141 and the discharge port 142 are provided in the upper cover 140,
the upper cover 140 is internally formed with the space or cavity
providing the silencer part 143, and the throat part 142a is formed
in the discharge port 142. This configuration can minimize
operation sound or noise of the pump.
[0052] The aforementioned embodiment is a mere example and does not
limit the scope of the invention. The present invention may be
embodied in other specific forms without departing from the
essential characteristics thereof.
[0053] For instance, the above embodiment uses the case 130 having
a stepped outer shape different in diameter between a part housing
the pump part and a part housing the motor part. An alternative is
to use a case 130a having a straight shape with no step,
substantially equal in diameter between a pump part and a motor
part, as shown in FIG. 6. This can achieve more improved
mountability in mounting an electric vacuum pump on a vehicle.
* * * * *