U.S. patent application number 15/578437 was filed with the patent office on 2018-05-31 for pump device.
This patent application is currently assigned to KYB Corporation. The applicant listed for this patent is KYB Corporation. Invention is credited to Koichiro AKATSUKA, Tomoyuki FUJITA, Hiroki GOMI, Fumiyasu KATOU, Tomoyuki NAKAGAWA.
Application Number | 20180149153 15/578437 |
Document ID | / |
Family ID | 57440401 |
Filed Date | 2018-05-31 |
United States Patent
Application |
20180149153 |
Kind Code |
A1 |
AKATSUKA; Koichiro ; et
al. |
May 31, 2018 |
PUMP DEVICE
Abstract
A pump device includes: a main pump and a sub pump; and a
switching valve that switches so as to supply the hydraulic oil
discharged from the sub pump to the hydraulic device, or to return
the hydraulic oil discharged from the sub pump to the suction side.
The main pump and the sub pump each include: a rotor, a discharge
port into which the hydraulic oil discharged from a pump chamber is
led, and a groove-shaped discharge-side notch formed from an
opening edge of the discharge port toward a direction opposite to a
rotation direction of the rotor. The switching valve switches
according to a rotation speed of the drive shaft. At least one
discharge-side notch of the sub pump is formed so that a resistance
applied to the flow of the hydraulic oil passing therethrough is
greater than that of the discharge-side notch of the main pump.
Inventors: |
AKATSUKA; Koichiro; (Gifu,
JP) ; FUJITA; Tomoyuki; (Gifu, JP) ; NAKAGAWA;
Tomoyuki; (Gifu, JP) ; KATOU; Fumiyasu;
(Aichi, JP) ; GOMI; Hiroki; (Gifu, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KYB Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
KYB Corporation
Tokyo
JP
|
Family ID: |
57440401 |
Appl. No.: |
15/578437 |
Filed: |
June 1, 2016 |
PCT Filed: |
June 1, 2016 |
PCT NO: |
PCT/JP2016/066137 |
371 Date: |
November 30, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 11/001 20130101;
F04C 14/02 20130101; F01C 21/108 20130101; F04C 14/26 20130101;
F01C 21/0863 20130101; F04C 2/3446 20130101; F04C 15/0049 20130101;
F04C 15/06 20130101; F04C 2270/13 20130101; F04C 11/00 20130101;
F04C 2270/12 20130101; F04C 2/344 20130101 |
International
Class: |
F04C 2/344 20060101
F04C002/344; F04C 11/00 20060101 F04C011/00; F04C 14/26 20060101
F04C014/26; F04C 15/06 20060101 F04C015/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2015 |
JP |
2015-112566 |
Claims
1. A pump device for supplying working fluid to a fluid pressure
device, the pump device comprising: a main pump configured to
supply the working fluid to the fluid pressure device through a
first discharge passage; a sub pump configured to supply the
working fluid to the fluid pressure device through a second
discharge passage that joins with the first discharge passage; a
return passage configured to return the working fluid discharged
from the sub pump to a suction side; and a switching valve
configured to switch regarding whether or not to return the working
fluid discharged from the sub pump to the suction side through the
return passage, wherein the main pump and the sub pump each
comprise: a rotor connected to a common drive shaft; a plurality of
vanes provided so as to be capable of reciprocating in a radial
direction relative to the rotor; a cam ring having an inner
peripheral surface, wherein distal ends of the vanes being
configured to be in sliding contact with the inner peripheral
surface in accordance with rotation of the rotor; pump chambers
defined by the rotor, the cam ring, and adjacent pair of the vanes;
a discharge port into which the working fluid discharged from the
pump chamber is led; and a groove-shaped discharge-side notch
formed from an opening edge of the discharge port toward a
direction opposite to a rotation direction of the rotor, wherein
the switching valve is configured to switch according to a rotation
speed of the drive shaft, and wherein at least one discharge-side
notch of the sub pump is formed so that a resistance applied to the
flow of the working fluid passing therethrough is greater than that
of the discharge-side notch of the main pump.
2. The pump device according to claim 1, wherein the main pump and
the sub pump each further comprise a suction port configured to
lead the working fluid to the pump chamber, and an opening area of
the discharge-side notch of the sub pump at a position separated
from a reference position by a predetermined angle is formed to be
smaller than an opening area of the discharge-side notch of the
main pump at a position separated from the reference position by a
predetermined angle, the reference position being a position of the
vane that is on the front side in the rotation direction among the
pair of vanes that define the pump chamber when communication
between the pump chamber and the discharge port is blocked in
accordance with the rotation of the rotor.
3. The pump device according to claim 1, wherein the main pump and
the sub pump each further comprise a groove-shaped suction-side
notch formed from an opening edge of the suction port toward the
direction opposite to the rotation direction of the rotor, the
suction port being configured to lead the working fluid to the pump
chamber, wherein at least one suction-side notch of the sub pump is
formed so that a resistance applied to the flow of the working
fluid passing therethrough is greater than that of the suction-side
notch of the main pump.
4. The pump device according to claim 1, wherein the switching
valve configured to switch so as to return the working fluid to the
suction side through the return passage when the rotation speed of
the drive shaft is at or above a predetermined pump rotation speed.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pump device.
BACKGROUND ART
[0002] JP2010-14101A discloses a multiple vane pump in which the
rotors of a first vane pump and a second vane pump are connected by
a common drive shaft so as to be connected in parallel.
[0003] During startup of this multiple vane pump, a working fluid
is supplied to a fluid pressure device by the first vane pump and
the second vane pump. In the multiple vane pump, if the rotation
speed of the pump increases and the discharge flow rate of the
second vane pump reaches or exceeds a necessary flow rate, the
working fluid discharged from the first vane pump is returned to a
suction passage, and working fluid is supplied to the fluid
pressure device by the second vane pump alone.
[0004] This kind of vane pump includes a groove-shaped notch which
is in communication with a discharge port in order to prevent
sudden fluctuations in the pressure of the working fluid that is
led to a high-pressure chamber.
SUMMARY OF INVENTION
[0005] In such a multiple vane pump, in order to prevent sudden
pressure fluctuations of the working fluid during high rotation of
the pump, the notch is formed so as to have a long length and a
large cross-section area so that the resistance applied to the flow
of working fluid passing therethrough is relatively small. During
high rotation of the pump, by decreasing the resistance applied by
the notch so as to promote the flow of working fluid from the
high-pressure chamber to a pump chamber through the notch, the rate
of pressure rise within the pump chamber relative to the rotation
angle of the pump increases. Thereby, the pump chamber communicates
with the high-pressure chamber in a state in which the pressure has
risen sufficiently such that sudden fluctuations in the pressure of
the working fluid are prevented, and the occurrence of vibrations
and noise during high rotation of the pump is suppressed.
[0006] However, during low rotation of the pump, the movement speed
of the vanes in the rotation direction of the rotor decreases
compared to that during high rotation of the pump, and thus the
flow of working fluid from the high-pressure chamber to the pump
chamber through the notch is easily promoted. Therefore, during low
rotation of the pump, the rate of pressure rise within the pump
chamber relative to the rotation angle of the pump is high.
Accordingly, if the length of the notch is formed to be relatively
long and the cross-section area of the notch is formed to be
relatively large, during low rotation of the pump, the rate of
pressure rise within the pump chamber relative to the rotation
angle of the pump may become too high. Consequently, if the notch
is formed to have a long length and a large cross-section area,
sudden pressure fluctuations may occur during low rotation of the
pump, and this can lead to the occurrence of vibrations and
noise.
[0007] An object of the present invention is to suppress the
occurrence of vibrations and noise in a pump device including a
main pump and a sub pump.
[0008] According to one aspect of the present invention, a pump
device for supplying working fluid to a fluid pressure device is
provided. The pump device includes: a main pump configured to
supply the working fluid to the fluid pressure device through a
first discharge passage, a sub pump configured to supply the
working fluid to the fluid pressure device through a second
discharge passage that joins with the first discharge passage, a
return passage configured to return the working fluid discharged
from the sub pump to a suction side, and a switching valve
configured to switch regarding whether or not to return the working
fluid discharged from the sub pump to the suction side through the
return passage. The main pump and the sub pump each include: a
rotor connected to a common drive shaft, a plurality of vanes
provided so as to be capable of reciprocating in a radial direction
relative to the rotor, a cam ring having an inner peripheral
surface. Distal ends of the vanes being configured to be in sliding
contact with the inner peripheral surface in accordance with
rotation of the rotor. The main pump and the sub pump each include:
pump chambers defined by the rotor, the cam ring, and adjacent pair
of the vanes, a discharge port into which the working fluid
discharged from the pump chamber is led, and a groove-shaped
discharge-side notch formed from an opening edge of the discharge
port toward a direction opposite to a rotation direction of the
rotor. The switching valve is configured to switch according to a
rotation speed of the drive shaft. At least one discharge-side
notch of the sub pump is formed so that a resistance applied to the
flow of the working fluid passing therethrough is greater than that
of the discharge-side notch of the main pump.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a cross-section view of a pump device according to
an embodiment of the present invention.
[0010] FIG. 2 is a plan view when viewed in the direction of arrow
A in FIG. 1 of a pump cartridge in a main pump of the pump device
according to the embodiment of the present invention.
[0011] FIG. 3 is a plan view when viewed in the direction of arrow
B in FIG. 1 of a pump cartridge in a sub pump of the pump device
according to the embodiment of the present invention.
[0012] FIG. 4 is a hydraulic circuit diagram of the pump device
according to the embodiment of the present invention.
[0013] FIG. 5 is a graph illustrating the flow rate characteristics
of the pump device according to the embodiment of the present
invention.
[0014] FIG. 6A is an enlarged view illustrating the relationship
among a pump chamber, a discharge port, and a notch in the main
pump of the pump device according to the embodiment of the present
invention.
[0015] FIG. 6B is an enlarged view illustrating the relationship
among a pump chamber, a discharge port, and a notch in the sub pump
of the pump device according to the embodiment of the present
invention.
[0016] FIG. 7A is a cross-section view illustrating a notch shape
of the notch in the main pump of the pump device according to the
embodiment of the present invention.
[0017] FIG. 7B is a cross-section view illustrating a notch shape
of the notch in the sub pump of the pump device according to the
embodiment of the present invention.
[0018] FIG. 7C is a view superimposing FIG. 7A and FIG. 7B.
[0019] FIG. 8A is a cross-section view illustrating an alternative
embodiment of the notch shape of the notch in the main pump of the
pump device according to the embodiment of the present
invention.
[0020] FIG. 8B is a cross-section view illustrating an alternative
embodiment of the notch shape of the notch in the sub pump of the
pump device according to the embodiment of the present
invention.
[0021] FIG. 8C is a view superimposing FIG. 8A and FIG. 8B.
[0022] FIG. 9A is a cross-section view illustrating another
alternative embodiment of the notch shape of the notch in the main
pump of the pump device according to the embodiment of the present
invention.
[0023] FIG. 9B is a cross-section view illustrating another
alternative embodiment of the notch shape of the notch in the sub
pump of the pump device according to the embodiment of the present
invention.
[0024] FIG. 9C is a view superimposing FIG. 9A and FIG. 9B.
[0025] FIG. 10 is a hydraulic circuit diagram illustrating an
alternative embodiment of the pump device according to the
embodiment of the present invention.
[0026] FIG. 11 is a plan view of a center plate in an alternative
embodiment of the pump device according to the embodiment of the
present invention.
DESCRIPTION OF EMBODIMENTS
[0027] A pump device 100 according to an embodiment of the present
invention will now be explained below referring to the
drawings.
[0028] The pump device 100 is used as a hydraulic supply source of
a hydraulic device mounted in a vehicle, such as a power steering
device or a transmission.
[0029] As shown in FIGS. 1 to 3, in the pump device 100, a rotor 2
of a main pump 101 and a rotor 2 of a sub pump 102 are connected to
a common drive shaft 1 to which motive power of an engine 24 (refer
to FIG. 4) is transmitted, and the rotors 2 are rotated by means of
the rotation of the drive shaft 1. FIGS. 2 and 3 respectively
illustrate pump cartridges 21 and 22 of the main pump 101 and the
sub pump 102, and FIG. 2 is a plan view when viewed from the
direction of arrow A in FIG. 1 whereas FIG. 3 is a plan view when
viewed from the direction of arrow B in FIG. 1. The rotor 2 rotates
clockwise in FIG. 2, and rotates counterclockwise in FIG. 3.
[0030] The hydraulic oil (working fluid) discharged from the main
pump 101 is constantly supplied to a hydraulic device (fluid
pressure device) 23 (refer to FIG. 4). Meanwhile, the hydraulic oil
discharged from the sub pump 102 is supplied to the hydraulic
device 23 or returned to the suction side according to the
operation of a switching valve 40 (refer to FIG. 4).
[0031] As shown in FIGS. 2 and 3, the main pump 101 and the sub
pump 102 include: a plurality of vanes 3 provided such that they
can move reciprocally in the radial direction relative to the rotor
2, and a cam ring 4 that accommodates the rotor 2. The distal end
of each vane 3 slidingly contacts a cam surface 4a on the inner
periphery of the cam ring 4 in accordance with the rotation of the
rotor 2.
[0032] In the rotor 2, slits 16 having an opening on the outer
peripheral surface are formed radially at predetermined intervals,
and the vanes 3 are slidably inserted into the slits 16.
[0033] On the base end side of each slit 16, a back pressure
chamber 17 to which pump discharge pressure is led is defined.
Adjacent back pressure chambers 17 communicate with each other by
an arc-shaped groove 2a formed in the rotor 2, and pump discharge
pressure is constantly led to the groove 2a. Each vane 3 is pressed
in the direction in which the vane 3 comes out from the slit 16 by
the pressure of the back pressure chamber 17 and the centrifugal
force generated by the rotation of the rotor 2, and the distal end
of each vane 3 abuts the cam surface 4a on the inner periphery of
the cam ring 4. Thereby, on the inside of the cam ring 4, a
plurality of pump chambers 7 are defined by the outer peripheral
surface of the rotor 2, the cam surface 4a of the cam ring, and the
adjacent pairs of vanes 3. Each pump cartridge 21, 22 is
constituted by the rotor 2, the vanes 3, and the cam ring 4.
[0034] The cam ring 4 is an annular member in which the cam surface
4a on the inner periphery has an approximately elliptical shape.
The cam ring 4 includes a suction region 4b that expands the
capacity of the pump chambers 7 in accordance with the rotation of
the rotor 2, and a discharge region 4b that contracts the capacity
of the pump chambers 7 in accordance with the rotation of the rotor
2.
[0035] A center plate 5 is disposed between the pump cartridges 21
and 22 of the main pump 101 and the sub pump 102, and a side plate
6 is disposed on the side of each pump cartridge 21, 22 (refer to
FIG. 1). In this way, each pump cartridge 21, 22 is sandwiched
between the center plate 5 and the side plate 6, and the pump
chambers 7 are sealed by the center plate 5 and the side plate
6.
[0036] In the center plate 5, suction ports 8, which open toward
the suction region 4b of the cam ring 4 and which lead hydraulic
oil to the pump chambers 7, are formed.
[0037] In each side plate 6, two arc-shaped discharge ports 9,
which open toward the discharge region 4c of the cam ring 4 and to
which hydraulic oil discharged by the pump chambers 7 is led, are
formed.
[0038] Groove-shaped notches (discharge-side notches) 9a, 9b, which
extend from the opening edges of the discharge ports 9 toward the
direction opposite of the rotation direction of the rotor 2, are
formed in the side plates 6 of the main pump 101 and the sub pump
102. By forming these notches 9a, 9b, the flow of hydraulic oil
from the pump chambers 7 to the discharge ports 9 through the
notches 9a, 9b is promoted in accordance with the rotation of the
rotor 2, and thus sudden pressure fluctuations in a high-pressure
chamber 12 to be explained later are prevented.
[0039] During the course of one rotation of the rotor 2, the pump
chambers 7 suction hydraulic oil through the suction port 8 in the
suction region 4b of the cam ring 4 and discharge the suctioned
hydraulic oil through the discharge port 9 in the discharge region
4c of the cam ring 4, and then suction hydraulic oil through the
suction port 8 in the suction region 4b of the cam ring 4 and
discharge the suctioned hydraulic oil through the discharge port 9
in the discharge region 4c of the cam ring 4. In this way, the pump
chambers 7 expand and contract in accordance with the rotation of
the rotor 2, and perform suction/discharge of the hydraulic oil two
times over the course of one rotation of the rotor 2.
[0040] As shown in FIG. 1, the drive shaft 1 is rotatably supported
via bushes 18 on a first pump body 10 and a second pump body 11.
The side plate 6 and the pump cartridge 21 of the main pump 101 are
laminated and accommodated within a pump accommodation recess 10a
formed in the first pump body 10. The side plate 6 and the pump
cartridge 22 of the sub pump 102 as well as the center plate 5 are
laminated and accommodated within a pump accommodation recess 11 a
formed in the second pump body 11. In this way, the main pump 101
is accommodated in the first pump body 10 and the sub pump 102 is
accommodated in the second pump body 11.
[0041] The surfaces having an opening of the first pump body 10 and
the second pump body 11 are abutted to each other to integrally
fasten the first pump body 10 and the second pump body 11 together,
and thereby the pump accommodation recesses 10a and 11a are
sealed.
[0042] The cam rings 4 and the side plates 6 of the main pump 101
and the sub pump 102 are restrained from rotating by two
positioning pins 19 (refer to FIGS. 2 and 3) that are inserted into
the center plate 5. Relative rotation of the center plate 5 and the
side plates 6 relative to the cam ring 4 is restricted by the
positioning pins 19. Thereby, positioning of the suction region 4b
of the cam ring 4 and the suction ports 8 of the center plate 5 is
achieved, and positioning of the discharge region 4c of the cam
ring 4 and the discharge ports 9 of the side plates 6 is
achieved.
[0043] In the first pump body 10 and the second body pump 11, a
high-pressure chamber 12 into which hydraulic oil discharged from
the discharge ports 9 flows is formed. The hydraulic oil of the
high-pressure chamber 12 is supplied to the hydraulic device 23
through a first discharge passage 32 and a second discharge passage
34 (refer to FIG. 4). The hydraulic oil of the high-pressure
chamber 12 is led to the arc-shaped groove 2a of the rotor 2
through a through-hole 6a formed in the side plates 6, and then is
led to the back pressure chambers 17.
[0044] Next, the hydraulic circuit of the pump device 100 will be
explained referring to FIG. 4.
[0045] A suction passage 31 connected to a tank 36 is connected to
the suction ports 8 of the main pump 101 and the sub pump 102.
[0046] The first discharge passage 32 is connected to the discharge
ports of the main pump 101, and hydraulic oil is constantly
supplied from the main pump 101 to the hydraulic device 23 through
the first discharge passage 32.
[0047] A switching passage 33 is connected to the discharge ports 9
of the sub pump 102. The switching valve 40, which switches the
flow of hydraulic oil discharged from the sub pump 102, is provided
in the switching passage 33.
[0048] The following are connected to the switching valve 40: the
second discharge passage 34 that supplies hydraulic oil to the
hydraulic device 23; and a return passage 35 that returns hydraulic
oil to the suction side. The second discharge passage 34 is
provided so as to join with the first discharge passage 32.
[0049] The switching valve 40 switches regarding whether or not to
return the hydraulic oil discharged from the sub pump 102 to the
suction side through the return passage 35. In more detail, the
switching valve 40 selectively switches so as to supply the
hydraulic oil discharged from the sub pump 102 to the hydraulic
device 23 through the second discharge passage 34, or to return the
hydraulic oil discharged from the sub pump 102 to the suction side
through the return passage 35. In other words, the hydraulic oil
discharged from the sub pump 102 is selectively led to either the
hydraulic device 23 or the suction passage 31 by the switching
operation of the switching valve 40.
[0050] The switching valve 40 has a first communication position
40a in which communication is established between the switching
passage 33 and the second discharge passage 34, and a second
communication position 40b in which communication is established
between the switching passage 33 and the return passage 35. The
switching valve 40 is an electromagnetic switching valve in which
the position is switched by a control current output from a
controller 30. The switching valve 40 is set to the second
communication position 40b by a biasing force of a spring 42 when a
solenoid 41 is not energized, and is set to the first communication
position 40a against the biasing force of the spring 42 when the
solenoid 41 is energized.
[0051] The position of the switching valve 40 is switched according
to, for example, the rotation speed of the engine 24 that is input
into the controller 30, i.e. a pump rotation speed which is the
rotation speed of the drive shaft 1 and the rotor 2. The switching
valve 40 is not limited to an electromagnetic switching valve, and
may also be a pilot-type switching valve in which the switching
operation is performed by a pilot liquid pressure.
[0052] In this way, the main pump 101 suctions hydraulic oil from
the tank 36 through the suction passage 31, and supplies the
hydraulic oil to the hydraulic device 23 through the first
discharge passage 32. The sub pump 102 suctions hydraulic oil from
the tank 36 through the suction passage 31, and supplies the
hydraulic oil to the hydraulic device 23 through the second
discharge passage 34 or returns the hydraulic oil to the suction
side through the return passage 35.
[0053] Next, the operation of the pump device 100 will be
explained.
[0054] During startup of the pump device 100, the switching valve
40 is set to the first communication position 40a.
[0055] Hydraulic oil discharged from the main pump 101 is supplied
to the hydraulic device 23 regardless of which position the
switching valve 40 is in.
[0056] Hydraulic oil discharged from the sub pump 102 is supplied
to the hydraulic device 23 through the second discharge passage
34.
[0057] Thereby, hydraulic oil in a flow rate which is the combined
total of the discharge flow rates of the main pump 101 and the sub
pump 102 is supplied to the hydraulic device 23.
[0058] FIG. 5 is a graph illustrating the relationship between the
discharge flow rate and the rotation speed of the pump device 100.
In FIG. 5, the solid line represents the overall discharge flow
rate of the pump device 100, and the dashed lines represent the
combined discharge flow rate of the main pump 101 and the sub pump
102 and the discharge flow rate of the main pump 101 alone. As
shown in FIG. 5, the discharge flow rate of the pump device 100
increases in accordance with an increase in the pump rotation
speed. If the pump rotation speed reaches a predetermined pump
rotation speed Ni and the discharge flow rate of the main pump 101
alone reaches or exceeds a required flow rate Q1 of the hydraulic
device 23, the switching valve 40 is switched to the second
communication position 40b. Thereby, the hydraulic oil discharged
from the sub pump 102 is returned to the suction side through the
return passage 35.
[0059] In this way, when the pump rotation speed is less than the
pump rotation speed Ni at which the discharge flow rate of the main
pump 101 reaches the required flow rate Q1 (hereinafter referred to
as "during low rotation of the pump"), hydraulic oil discharged
from the main pump 101 and the sub pump 102 is supplied to the
hydraulic device 23. Further, when the pump rotation speed is at or
above the pump rotation speed N1 (hereinafter referred to as
"during high rotation of the pump"), the discharge flow rate of the
main pump 101 alone is supplied to the hydraulic device 23, and the
hydraulic oil discharged from the sub pump 102 is returned to the
suction side. In other words, the sub pump 102 is used as a
pressure source supplying hydraulic oil to the hydraulic device 23
during low rotation of the pump, and is not used as such a pressure
source during high rotation of the pump.
[0060] Next, referring to FIGS. 6 and 7, the notch shape of the
main pump 101 and the sub pump 102 will be explained in detail. In
the following, a state in which communication between the pump
chamber 7 and the suction port 8 is blocked in accordance with
rotation of the rotor 2 will be referred to as a "reference state"
(the dashed lines in FIG. 6), a state in which there is direct
communication between the pump chamber 7 and the discharge port 9
without using the notches 9a, 9b will be referred to as a
"communication state" (the solid lines in FIG. 6), and a region in
the space between the reference state and the communication state
will be referred to as a "transition region". Further, a position
in the reference state of a vane 3b which is on the front side in
the rotation direction among the pair of vanes 3a, 3b that define
the pump chamber 7 will be referred to as a "reference position"
(refer to FIG. 6), and a cross-section area that intersects a
center line C (refer to FIGS. 2, 3, and 6) of the notches 9a, 9b at
a position separated by an angle a from the reference position will
be referred to as a "notch opening area".
[0061] The notches 9a, 9b of the main pump 101 and the sub pump 102
are formed so that the cross-section shape that is perpendicular to
the longitudinal direction thereof, i.e. the cross-section shape
intersecting the center line C, is an approximately triangular
shape. Further, the notches 9a, 9b of the main pump 101 and the sub
pump 102 are formed in a tapered shape in which the cross-section
area of the notch gradually decreases from the opening edge on the
rear side in the rotation direction of the discharge port 9 toward
the rear in the rotation direction of the rotor 2.
[0062] FIGS. 6A and 6B illustrate the relationship among the pump
chamber 7, the suction port 8, the discharge port 9, and the
notches 9a, 9b. As shown in FIGS. 6A and 6B, the relationship among
the pump chamber 7, the suction port 8, and the discharge port 9 is
the same in the main pump 101 and the sub pump 102, but the shapes
of the notches 9a and 9b are different from each other.
[0063] The notch 9b of the sub pump 102 is formed so that the
resistance applied to the flow of hydraulic oil passing
therethrough is greater than that of the notch 9a of the main pump
101 in the space where the vane 3b on the front side in the
rotation direction passes through the transition region from the
reference state shown by the dashed lines in FIG. 6B to the
communication state shown by the solid lines in FIG. 6B. In other
words, the notch 9b of the sub pump 102 is formed so that the
pressure loss of the hydraulic oil led from the pump chamber 7
through the notch 9b increases compared to the notch 9a of the main
pump 101 in the space where the vane 3b passes through the
transition region. In detail, in at least a portion within the
range of the transition region, an opening area S2 (refer to FIG.
7B) of the notch 9b at a position separated from the reference
position by an angle a (refer to FIGS. 6A and 6B) in the sub pump
102 is formed to be smaller than an opening area Si (refer to FIG.
7A) of the notch 9a at a position separated from the reference
position by an angle a in the main pump 101.
[0064] In the pump device 100 according to the present embodiment,
as shown in FIGS. 6A and 6B and FIGS. 7A to 7C, the notches 9a, 9b
of the main pump 101 and the sub pump 102 are formed so that the
depths D and the opening widths W are equivalent to each other. In
contrast, as shown in FIGS. 7A to 7C, the lengths of the notches
9a, 9b toward the rotation direction of the rotor 2 are formed so
that a length L2 of the notch 9b in the sub pump 102 is shorter
than a length L1 of the notch 9a in the main pump 101. By forming
the notches 9a, 9b of the main pump 101 and the sub pump 102 in
this way, the opening area S2 of the notch 9b in the sub pump 102
is smaller than the opening area S1 of the notch 9a in the main
pump 101. Thereby, the notch 9b of the sub pump 102 applies a
greater resistance to the flow of hydraulic oil passing
therethrough than the notch 9a of the main pump 101.
[0065] Herein, a pump device as a comparative embodiment will be
explained in order to facilitate the understanding of the pump
device 100.
[0066] The main pump and the sub pump in the pump device according
to the comparative embodiment have groove-shaped notches that are
formed in the same shape and extend from the opening edge of the
discharge port toward the rear side in the rotation direction of
the rotor. The notches are formed so that the lengths are long and
the cross-section areas are large, and the resistance applied to
the hydraulic oil is relatively small.
[0067] During high rotation of the pump, the movement speed of the
vanes in the rotation direction of the rotor is fast, and thus it
becomes difficult to lead hydraulic oil from the discharge ports
into the pump chambers through the notches, and the rate of
pressure rise within the pump chambers is slow compared to during
low rotation. Therefore, in the pump device according to the
comparative embodiment, the notches are formed so that the
resistance applied to the hydraulic oil passing therethrough is
relatively small, and thus it becomes easier to lead hydraulic oil
from the discharge ports into the pump chambers through the
notches. Thereby, even during high rotation of the pump in which
the rate of pressure rise is relatively slow, the pressure
difference between the pump chambers and the high-pressure chamber
decreases when the pump chambers and the high-pressure chamber are
in direct communication, and pressure fluctuations can be
moderated. Therefore, the occurrence of noise and vibrations during
high rotation of the pump can be suppressed. In this way, the
notches of pump device according to the comparative embodiment are
formed in shapes for suppressing the occurrence of noise and
vibrations during high rotation.
[0068] Meanwhile, during low rotation of the pump, the movement
speed of the vanes in the rotation direction of the rotor is slow,
and thus it becomes easy to lead hydraulic oil from the discharge
ports into the pump chambers through the notches compared to during
high rotation of the pump, and the rate of pressure rise within the
pump chambers becomes relatively fast. Therefore, during low
rotation of the pump in the pump device according to the
comparative embodiment, the rate of pressure rise is fast compared
to during high rotation, and hydraulic oil from the discharge ports
is led to the pump chambers through the notches which further
promotes the rise in pressure, and this causes sudden fluctuations
in the pressure within the pump chambers. Therefore, noise and
vibrations occur during low rotation of the pump in the main pump
and the sub pump of the pump device according to the comparative
embodiment.
[0069] In contrast, in the pump device 100, the notches 9a of the
main pump 101 are formed so that the resistance applied to the
hydraulic oil passing therethrough is relatively small, and the
notches 9b of the sub pump 102 are formed so that the resistance
applied to the hydraulic oil passing therethrough is large compared
to the notches 9a of the main pump 101. Thereby, during low
rotation of the pump in the sub pump 102, a situation in which an
excessive amount of hydraulic oil is led from the discharge ports 9
to the pump chambers 7 through the notches 9b is suppressed.
Therefore, sudden increases in the pressure of the pump chambers 7
of the sub pump 102 during low rotation are prevented, and pressure
fluctuations when the pump chambers 7 are in direct communication
with the discharge ports 9 become moderate, and the occurrence of
noise and vibrations can be suppressed.
[0070] During high rotation of the pump, the discharge ports 9 of
the sub pump 102 communicate with the return passage 35, and
hydraulic oil discharged from the sub pump 102 is returned to the
suction side. In other words, the pump chambers 7 of the sub pump
102 during high rotation of the pump communicate with the discharge
ports 9 which communicate with the suction side and have low
pressure. In this way, even with the notches 9b in which the
resistance applied to the flow of hydraulic oil passing
therethrough is relatively large, i.e. even with the notches 9b
that is formed in a shape conforming to low rotation of the pump,
during high rotation of the pump, the high-pressure chamber 12
communicates with the suction side and pressure is released, and
thus sudden fluctuations of the pressure in the high-pressure
chamber 12 of the sub pump 102 do not occur. Therefore, the
occurrence of vibrations and noise in the sub pump 102 during high
rotation is suppressed.
[0071] In other words, the notches 9a of the main pump 101, which
is used during low rotation of the pump and during high rotation of
the pump, are formed in a shape for suppressing noise and
vibrations during high rotation, and the notches 9b of the sub pump
102, which is not used during high rotation, are formed in a shape
for suppressing noise and vibrations during low rotation. Thereby,
vibrations and noise can be suppressed in the pump device 100.
[0072] According to the above embodiment, the following effects are
achieved.
[0073] According to the pump device 100, the sub pump 102 has
notches 9b in which the resistance applied to hydraulic oil passing
therethrough is greater than that of the main pump 101, and thus
during low rotation of the pump, the flow of hydraulic oil passing
through the notches 9b is suppressed by the resistance. Therefore,
sudden fluctuations in the pressure of the hydraulic oil when the
pump chambers 7 and the high-pressure chamber 12 are in
communication are prevented, and the occurrence of vibrations and
noise in the sub pump 102 during low rotation of the pump can be
suppressed. Further, if the rotation speed of the pump device 100
increases, hydraulic oil discharged from the sub pump 102 is led to
the suction side of the low pressure by the switching valve 40.
Therefore, even if the sub pump 102 is provided with the notches 9b
that apply a relatively large resistance to the hydraulic oil, the
occurrence of vibrations and noise in the sub pump 102 during high
rotation can be suppressed. Accordingly, the occurrence of
vibrations and noise can be suppressed in the pump device 100 which
includes the main pump 101 and the sub pump 102.
[0074] Next, an alternative embodiment of the above-described
embodiment will be explained.
[0075] In the above-described embodiment, the main pump 101 and the
sub pump 102 do not have notches that communicate with the suction
ports 8. However, as shown in FIG. 11, groove-shaped notches
(suction-side notches) 8a, 8b that extend from the opening edge of
the suction ports 8 in the direction opposite to the rotation
direction of the rotor 2 may be formed in the center plate 5. In
this case as well, the suction-side notches 8b of the sub pump 102
are preferably formed so that the resistance applied to hydraulic
oil passing therethrough becomes greater compared to the
suction-side notches 8a of the main pump 101, such that, for
example, the length of the suction-side notches 8b of the sub pump
102 is less than that of suction-side notches 8a of the main pump
101 as shown in FIG. 11. Thereby, in the sub pump 102 during low
rotation of the pump, pressure fluctuations when the pump chambers
7 on the high-pressure side and the discharge ports 8 on the
low-pressure side are in communication can be moderated. Therefore,
the occurrence of noise and vibrations in the pump device 100 can
be further suppressed. FIG. 11 is a plan view of the center plate 5
when viewed from the sub pump 102 side, and the arrow in FIG. 11
represents the rotation direction of the rotor 2.
[0076] The notch shapes of the main pump 101 and the sub pump 102
are not limited to the shapes described above, and any shape can be
used as long as the notches 9b of the sub pump 102 are formed so
that the resistance applied to the hydraulic oil is greater than
that of the notches 9a of the main pump 101. Concrete embodiments
thereof shall be explained below referring to FIGS. 8 and 9. FIGS.
8 and 9 are cross-section views illustrating the opening area of
the notches 9a, 9b of the main pump 101 and the sub pump 102 in the
reference state.
[0077] As shown in FIG. 8, the notches 9a, 9b of the main pump 101
and the sub pump 102 may be formed so that the lengths L and the
opening widths (not illustrated) are equivalent to each other,
whereas the depth D2 of the notch 9b of the sub pump 102 is smaller
than the depth D1 of the notch 9a of the main pump 101. Thereby,
the resistance applied to the hydraulic oil passing through the
notch 9b of the sub pump 102 becomes greater than that of the notch
9a of the main pump 101.
[0078] Further, as shown in FIG. 9, comparing the transition
regions of the main pump 101 and the sub pump 102, a region R1 in
which the opening area S2 of the notch 9b of the sub pump 102 is
larger than the opening area Si of the notch 9a of the main pump
101 and a region R2 in which the opening area S2 of the notch 9b of
the sub pump 102 is smaller than the opening area Si of the notch
9a of the main pump 101 may be formed. In this case as well, the
notches 9a, 9b of the main pump 101 and the sub pump 102 are formed
so that the notch 9b of the sub pump 102 applies a greater
resistance on the whole to the hydraulic oil passing therethrough
compared to the notch 9a of the main pump 101 in the space where
the vane 3b on the front side in the rotation direction moves
through the transition region. Thereby, effects similar to those of
the above-described embodiment are achieved.
[0079] In the above-described embodiment, the main pump 101 and the
sub pump 102 have the same number of vanes 3. Instead of this
configuration, the number of vanes 3 in the main pump 101 may be
different from that in the sub pump 102. If the number of vanes 3
is different between the main pump 101 and the sub pump 102, the
capacity of each pump chamber 7 defined by the vanes 3 will also
differ, and thus the positions in the circumferential direction at
which the discharge ports 8 are formed will be different. In this
case as well, the notch 9b of the sub pump 102 applies a greater
resistance on the whole to the hydraulic oil passing therethrough
compared to the notch 9a of the main pump 101 in the space where
the vane 3b on the front side in the rotation direction that
defines the pump chamber 7 moves through the transition region.
Thereby, effects similar to those of the above-described embodiment
are achieved.
[0080] In the above-described embodiment, the two notches 9a of the
main pump 101 are formed in the same shape as each other. The two
notches 9b of the sub pump 102 are also formed in the same shape as
each other. Instead of this configuration, the notches 9a of the
main pump 101 may be formed in different shapes from each other.
Further, the notches 9b of the sub pump 102 may also be formed in
different shapes from each other. In order to suppress noise and
vibrations of the pump device 100, both of the two notches 9b of
the sub pump 102 preferably apply a greater resistance to the
hydraulic oil than the notches 9a of the main pump 101. However,
for example, one notch 9b of the sub pump 102 may be formed in the
same shape as that of the notches 9a of the main pump 101, while
the other notch 9b may be formed so as to apply a greater
resistance to hydraulic oil passing therethrough than the notches
9a of the main pump 101. In this way, as long as at least one of
the notches 9b of the sub pump 102 is formed so as to apply a
greater resistance to hydraulic oil passing therethrough than the
notches 9a of the main pump 101.
[0081] In the above-described embodiment, the main pump 101 and the
sub pump 102 each have two discharge ports 9. Instead of this
configuration, there may be one discharge port 9, or three or more
discharge ports 9. In these cases as well, as long as at least one
of the notches 9b of the sub pump 102 is formed so as to apply a
greater resistance to hydraulic oil passing therethrough than the
notches 9a of the main pump 101.
[0082] In the above-described embodiment, a single notch 9a, 9b is
formed to be in communication with each discharge port 9 in the
main pump 101 and the sub pump 102. Instead of this configuration,
two or more notches 9a, 9b that communicate with a single discharge
port 9 may be formed. In this case, the notches 9a, 9b of the main
pump 101 and the sub pump 102 may be formed so that the total
resistance applied to the hydraulic oil passing through the
plurality of notches 9b that communicate with one discharge port 9
of the sub pump 102 is greater than the total resistance applied to
the hydraulic oil passing through the notches 9a that communicate
with one of the discharge ports 9 of the main pump 101.
[0083] In the above-described embodiment, the switching valve 40 is
provided to the switching passage 33, and the second discharge
passage 34 and the return passage 35 are connected to the switching
valve 40. Instead of this configuration, as shown in FIG. 10, the
second discharge passage 34 may be in direct communication with the
sub pump 102 and the return passage 35 may be provided so as to
branch from the second discharge passage 34. In this case, a check
valve 37 that permits only the flow of hydraulic oil from the
second discharge passage 34 to the first discharge passage 32 is
provided to the second discharge passage 34, and the return passage
35 is provided so as to branch from the upstream side of the check
valve 37 in the second discharge passage 34. Further, a switching
valve 140 is provided to the return passage 35. The switching valve
140 has a blocked position 140a in which the return passage 35 is
blocked, and an open position 140b in which the return passage 35
is opened. The position switching operation of the switching valve
140 switches regarding whether or not to return the hydraulic oil
discharged from the sub pump 102 to the suction side through the
return passage 35. The pump device 100 may have such a
configuration, and even in this case, the pump device 100 achieves
effects similar to those of the above-described embodiment.
[0084] Embodiments of this invention were described above, but the
above embodiments are merely examples of applications of this
invention, and the technical scope of this invention is not limited
to the specific constitutions of the above embodiments.
[0085] This application claims priority based on Japanese Patent
Application No.2015-112566 filed with the Japan Patent Office on
Jun. 2, 2015, the entire contents of which are incorporated into
this specification by reference.
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