U.S. patent application number 16/333211 was filed with the patent office on 2019-07-18 for variable capacity pump and working oil supply system for internal combustion engine.
This patent application is currently assigned to HITACHI AUTOMOTIVE SYSTEMS, LTD.. The applicant listed for this patent is HITACHI AUTOMOTIVE SYSTEMS, LTD.. Invention is credited to Atsushi NAGANUMA, Hideaki OHNISHI, Koji SAGA, Yasushi WATANABE.
Application Number | 20190219053 16/333211 |
Document ID | / |
Family ID | 61618812 |
Filed Date | 2019-07-18 |
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United States Patent
Application |
20190219053 |
Kind Code |
A1 |
NAGANUMA; Atsushi ; et
al. |
July 18, 2019 |
VARIABLE CAPACITY PUMP AND WORKING OIL SUPPLY SYSTEM FOR INTERNAL
COMBUSTION ENGINE
Abstract
Provided is a variable capacity pump where ease of control can
be improved. A variable capacity pump includes a control chamber
and a control valve. The control chamber is disposed between a pump
accommodating chamber and a movable member, and the volume of the
control chamber is variable with the movement of the movable
member. Working oil discharged from a discharge portion is
introduced into the control chamber. The control valve is provided
in a passage and, with the movement of a valve element, the control
valve varies the cross-sectional area of a flow passage, through
which working oil in the control chamber is drained to a low
pressure portion, while making the discharge portion and the
control chamber communicate with each other.
Inventors: |
NAGANUMA; Atsushi;
(Atsugi-shi, Kanagawa, JP) ; OHNISHI; Hideaki;
(Atsugi-shi, Kanagawa, JP) ; WATANABE; Yasushi;
(Aiko-gun, Kanagawa, JP) ; SAGA; Koji; (Ebina-shi,
Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI AUTOMOTIVE SYSTEMS, LTD. |
Hitachinaka-shi, Ibaraki |
|
JP |
|
|
Assignee: |
HITACHI AUTOMOTIVE SYSTEMS,
LTD.
Hitachinaka-shi, Ibaraki
JP
|
Family ID: |
61618812 |
Appl. No.: |
16/333211 |
Filed: |
August 4, 2017 |
PCT Filed: |
August 4, 2017 |
PCT NO: |
PCT/JP2017/028361 |
371 Date: |
March 13, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 2/344 20130101;
F04C 15/06 20130101; F04C 14/22 20130101; F04B 49/125 20130101;
F04B 49/22 20130101; F04C 14/223 20130101; F04C 2210/206
20130101 |
International
Class: |
F04C 14/22 20060101
F04C014/22; F04C 2/344 20060101 F04C002/344; F04C 15/06 20060101
F04C015/06; F04B 49/22 20060101 F04B049/22 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 2016 |
JP |
2016-181736 |
Claims
1. A variable capacity pump comprising: a housing including a pump
accommodating chamber therein; a pump structure disposed in the
pump accommodating chamber, and configured to vary volumes of a
plurality of working chambers with rotation, the pump structure
being further configured to discharge from a discharge portion
working oil introduced from an intake portion by being rotationally
driven; a movable member disposed in the pump accommodating
chamber, and accommodating the pump structure to define the
plurality of working chambers, the movable member being configured
to cause an amount of increase or decrease in volume of each of the
plurality of working chambers during rotation of the pump structure
to be varied by moving so that an amount of eccentricity of a
center of an inner periphery of the movable member from a center of
rotation of the pump structure varies; a first biasing member
disposed in the pump accommodating chamber in a state where a set
load is applied to the first biasing member, and configured to bias
the movable member in a direction that the amount of increase or
decrease in volume of each of the plurality of working chambers
increases; a first control chamber which is disposed between the
pump accommodating chamber and the movable member, and into which
the working oil discharged from the discharge portion is
introduced, a volume of the first control chamber increasing with
movement of the movable member in a direction opposing a biasing
force of the first biasing member; a second control chamber which
is disposed between the pump accommodating chamber and the movable
member, and into which the working oil discharged from the
discharge portion is introduced through a passage, a volume of the
second control chamber being variable with movement of the movable
member; and a control valve provided in the passage, and configured
to vary, with movement of a valve element, a cross-sectional area
of a flow passage, through which working oil in the second control
chamber is drained to a low pressure portion, while making the
discharge portion and the second control chamber communicate with
each other.
2. The variable capacity pump according to claim 1, wherein with
movement of the valve element in a first direction, the control
valve increases the cross-sectional area of the flow passage,
through which working oil in the second control chamber is drained
to the low pressure portion, while decreasing a cross-sectional
area of a flow passage, through which working oil is introduced
from the discharge portion to the second control chamber.
3. The variable capacity pump according to claim 1, wherein with
movement of the valve element in a second direction, the control
valve decreases the cross-sectional area of the flow passage,
through which working oil in the second control chamber is drained
to the low pressure portion, while increasing a cross-sectional
area of a flow passage through which working oil is introduced from
the discharge portion to the second control chamber.
4. The variable capacity pump according to claim 1, wherein the
control valve is configured to continuously change a position of
the valve element.
5. The variable capacity pump according to claim 4, wherein the
control valve is configured to stop the valve element at any
position.
6. The variable capacity pump according to claim 1, wherein the
control valve includes a solenoid portion configured to generate an
electromagnetic force for biasing the valve element.
7. The variable capacity pump according to claim 6, wherein the
solenoid portion is configured to move the valve element to any
position according to a control signal.
8. The variable capacity pump according to claim 6, wherein the
valve element is integrally coupled to a plunger of the solenoid
portion.
9. The variable capacity pump according to claim 1, wherein the
control valve includes a hollow member which accommodates the valve
element, and which has a first port communicating with the
discharge portion, a second port communicating with the second
control chamber, and a third port communicating with a low pressure
portion, openings of the first port, the second port, and the third
port being formed on an inner periphery of the hollow member.
10. The variable capacity pump according to claim 9, wherein the
control valve includes a solenoid portion configured to generate an
electromagnetic force for biasing the valve element, and the valve
element includes a first land portion disposed on a first port
side, and biased to one side by the solenoid portion, a second land
portion disposed on a third port side, and biased to an opposite
side by a second biasing member, and a connecting portion
connecting the first land portion and the second land portion with
each other.
11. The variable capacity pump according to claim 10, wherein the
second land portion varies an area of the opening of the third port
as the first land portion varies an area of the opening of the
first port.
12. The variable capacity pump according to claim 9, wherein the
control valve includes a solenoid portion configured to generate an
electromagnetic force for biasing the valve element, the opening of
the second port is disposed between the opening of the first port
and the opening of the third port, the valve element includes a
land portion biased to one side by the solenoid portion, and biased
to the opposite side by a second biasing member, and the land
portion varies an area of the opening of the second port
communicating with the opening of the first port, and an area of
the opening of the second port communicating with the opening of
the third port.
13. The variable capacity pump according to claim 1, wherein a
volume of the second control chamber increases with movement of the
movable member in the same direction as a direction of a biasing
force of the first biasing member.
14. The variable capacity pump according to claim 13, wherein the
movable member includes a first pressure receiving surface facing
the first control chamber, and a second pressure receiving surface
facing the second control chamber, and having a pressure receiving
area larger than a pressure receiving area of the first pressure
receiving surface.
15. The variable capacity pump according to claim 13, wherein the
movable member is configured to oscillate around a fulcrum in the
pump accommodating chamber.
16. The variable capacity pump according to claim 13, wherein the
movable member is configured to perform a translational motion in
the pump accommodating chamber.
17. The variable capacity pump according to claim 1, wherein a
volume of the second control chamber increases with movement of the
movable member in a direction opposing the biasing force of the
first biasing member.
18. A variable capacity pump comprising: a housing including a pump
accommodating chamber therein; a pump structure disposed in the
pump accommodating chamber, and configured to vary volumes of a
plurality of working chambers with rotation, the pump structure
being configured to discharge from a discharge portion working oil,
which is introduced from an intake portion by being rotationally
driven; a movable member disposed in the pump accommodating
chamber, and accommodating the pump structure to define the
plurality of working chambers, the movable member being configured
to cause an amount of increase or decrease in volume of each of the
plurality of working chambers during rotation of the pump structure
to be varied by moving so that an amount of eccentricity of a
center of an inner periphery of the movable member from a center of
rotation of the pump structure varies; a first control chamber
which is disposed between the pump accommodating chamber and the
movable member, and into which working oil discharged from the
discharge portion is introduced, a volume of the first control
chamber increasing with movement of the movable member to one side,
a second control chamber which is disposed between the pump
accommodating chamber and the movable member, and into which the
working oil discharged from the discharge portion is to be
introduced through a passage, a volume of the second control
chamber being variable with movement of the movable member; a
cylindrical member having a hollow shape, and including a first
port communicating with the discharge portion, a second port
communicating with the second control chamber, and a third port
communicating with a low pressure portion, openings of the first
port, the second port, and the third port being formed on an inner
periphery of the cylindrical member; and a control valve including
a spool movable in the cylindrical member, and a solenoid portion
configured to move the spool, wherein the spool includes a first
large diameter portion configured to vary an area of the opening of
the first port, and a second large diameter portion configured to
vary an area of the opening of the third port, and the first large
diameter portion and the second large diameter portion are disposed
on the inner periphery of the cylindrical member within a range
sandwiched between the first large diameter portion and the second
large diameter portion such that the first port, the second port,
and the third port are allowed to be at least partially open
simultaneously.
19. A working oil supply system for an internal combustion engine,
the working oil supply system comprising: a variable capacity pump
which introduces working oil discharged from a pump structure into
a control chamber disposed around a movable member, which
accommodates the pump structure therein, so as to move the movable
member to vary an amount of eccentricity of a center of the movable
member from a center of rotation of the pump structure, thus
varying a pressure of working oil discharged from the pump
structure to the internal combustion engine; a pressure measuring
portion configured to measure a pressure of working oil discharged
from the pump structure; a rotational speed measuring portion
configured to measure a rotational speed of the internal combustion
engine; and a control portion which calculates a pressure
difference between a pressure measured by the pressure measuring
portion and a pressure of working oil which the internal combustion
engine is required to have at the rotational speed measured by the
rotational speed measuring portion, the control portion varying,
when the rotational speed is equal to or more than a predetermined
rotational speed, and the pressure difference is larger than a
predetermined pressure difference, a drainage amount of working oil
from the control chamber to a low pressure portion while allowing
working oil to be introduced into the control chamber until the
pressure difference becomes equal to or less than the predetermined
pressure difference.
20. The working oil supply system for an internal combustion engine
according to claim 19, wherein the control portion does not drain
working oil from the control chamber to the low pressure portion
when the rotational speed is less than the predetermined rotational
speed.
Description
TECHNICAL FIELD
[0001] The present invention relates to a variable capacity
pump.
BACKGROUND ART
[0002] Conventionally, variable capacity pumps are known.
CITATION LIST
Patent Literature
[0003] PTL 1: Japanese Patent Laid-Open No. S59-70891
SUMMARY OF INVENTION
Technical Problem
[0004] Conventional variable capacity pumps have room for
improvement in terms of ease of control.
Solution to Problem
[0005] A variable capacity pump according to one embodiment of the
present invention preferably includes a control portion which
varies the cross-sectional area of the flow passage through which
working oil in a control chamber is drained while making a
discharge portion and a control chamber communicate with each
other.
[0006] Accordingly, ease of control can be improved.
BRIEF DESCRIPTION OF DRAWINGS
[0007] FIG. 1 is a circuit diagram of a working oil supply system
for an engine of a first embodiment.
[0008] FIG. 2 is a front view showing a portion of a pump of the
first embodiment.
[0009] FIG. 3 is a schematic view of a control valve in the first
embodiment.
[0010] FIG. 4 is a view showing an operation state of the pump of
the first embodiment.
[0011] FIG. 5 is a view showing the operation state of the pump of
the first embodiment.
[0012] FIG. 6 is a view showing the operation state of the pump of
the first embodiment.
[0013] FIG. 7 is a graph showing the relationship between a duty
ratio D of a solenoid in the first embodiment and the opening area
S of a port.
[0014] FIG. 8 is a graph showing the relationship between a duty
ratio D of the solenoid and a pressure p in a second control
chamber, in the first embodiment.
[0015] FIG. 9 is a graph showing the relationship between a duty
ratio D of the solenoid and an amount of eccentricity .DELTA. of a
cam ring, in the first embodiment.
[0016] FIG. 10 is a graph showing the relationship between a duty
ratio D of the solenoid and a discharge pressure P, in the first
embodiment.
[0017] FIG. 11 is a graph showing the relationship between an
engine speed Ne and a discharge pressure P which are realized by
the pump.
[0018] FIG. 12 is a graph showing a portion of FIG. 11 in an
enlarged manner.
[0019] FIG. 13 is a schematic view of a control valve in a second
embodiment.
[0020] FIG. 14 is a view showing an operation state of a pump of
the second embodiment.
[0021] FIG. 15 is a view showing the operation state of the pump of
the second embodiment.
[0022] FIG. 16 is a view showing the operation state of the pump of
the second embodiment.
[0023] FIG. 17 is a cross-sectional view of a portion of a pump of
a third embodiment.
[0024] FIG. 18 is a schematic view of a control valve in a third
embodiment.
[0025] FIG. 19 is a view showing an operation state of a pump of
the third embodiment.
[0026] FIG. 20 is a cross-sectional view of a portion of a pump of
a fourth embodiment.
[0027] FIG. 21 is a schematic view of a control valve in the fourth
embodiment.
[0028] FIG. 22 is a view showing an operation state of the pump of
the fourth embodiment.
DESCRIPTION OF EMBODIMENTS
[0029] Hereinafter, embodiments for carrying out the present
invention are described with reference to drawings.
First Embodiment
[0030] First, the configuration is described. A variable capacity
pump (hereinafter referred to as "pump") 2 of this embodiment is an
oil pump used in a working oil supply system 1 of an internal
combustion engine (engine) of an automobile. The pump 2 is disposed
at a front end portion or the like of a cylinder block of the
engine. The pump 2 supplies oil (working oil), which is a fluid
having functions, such as lubrication, to respective slide portions
of the engine, and to a variable valve device (valve timing control
device and the like) which variably controls operation
characteristics of a valve of the engine. As shown in FIG. 1, the
working oil supply system 1 of the engine includes an oil pan 400,
a passage 4, the pump 2, a pressure sensor (pressure measuring
portion) 51, a rotational speed sensor (rotational speed measuring
portion) 52, and an engine control unit (control portion) 6. The
oil pan 400 is a low pressure portion which is disposed below the
engine, and where working oil is stored. The passage 4 is disposed
in the cylinder block, for example, and has an intake passage 40, a
discharge passage 41, a main gallery 42, a control passage 43, and
a relief passage 44. One end of the intake passage 40 is connected
to the oil pan 400 by way of an oil filter 401. The other end of
the intake passage 40 is connected to the pump 2. One end of the
discharge passage 41 is connected to the pump 2. The other end of
the discharge passage 41 is connected to the main gallery 42. An
oil filter 410 and the pressure sensor 51 are provided in the
discharge passage 41. The main gallery 42 is connected to the
respective slide portions of the engine, the variable valve device
and the like. The relief passage 44 is branched from the discharge
passage 41, and is connected to the oil pan 400. A relief valve 440
is provided in the relief passage 44.
[0031] As shown in FIG. 2, the pump 2 is a vane pump. The pump 2
includes a housing, a shaft (drive shaft) 21, a rotor 22, a
plurality of vanes 23, a cam ring 24, a spring (first biasing
member) 25, a first sealing member 261, a second sealing member
262, a pin 27, and a control mechanism 3. The housing includes a
housing body 20 and a cover. FIG. 2 shows the pump 2 from which the
cover is removed. The housing body 20 has, on the inside thereof, a
pump accommodating chamber 200, an intake opening (intake portion)
201, and a discharge opening (discharge portion) 203. The pump
accommodating chamber 200 has a bottomed cylindrical shape, and
opening of the pump accommodating chamber 200 is formed in one side
surface of the housing body 20. A hole (shaft accommodating hole),
in which the drive shaft 21 is accommodated, and a hole (pin hole),
in which the pin 27 is fixed, are formed in a bottom surface of the
pump accommodating chamber 200. The cover is mounted on the one
side surface of the housing body 20 by a plurality of bolts, thus
closing the opening of the pump accommodating chamber 200. One end
of the intake opening 201 is open on the outer surface of the
housing body 20, and the other end of the intake passage 40 is
connected to the one end of the intake opening 201. The other end
of the intake opening 201 is open on the bottom surface of the pump
accommodating chamber 200 as an intake port 202. The intake port
202 is a groove (recessed portion) extending in a circumferential
direction of the shaft accommodating hole, and is disposed on a
side opposite to the pin hole with respect to the shaft
accommodating hole. One end of the discharge opening 203 is formed
in the bottom surface of the pump accommodating chamber 200 as a
discharge port 204. The discharge port 204 is a groove (recessed
portion) extending in a circumferential direction of the shaft
accommodating hole, and is disposed on the pin hole side of the
shaft accommodating hole. The other end of the discharge opening
203 is formed in the outer surface of the housing body 20, and one
end of the discharge passage 41 is connected to the other end of
the discharge opening 203. Grooves which correspond to the intake
port 202 and the discharge port 204 of the housing body 20 are also
formed on a surface of the cover which closes the pump
accommodating chamber 200. The rotor 22, the plurality of vanes 23,
the cam ring 24, and the spring 25 are disposed in the pump
accommodating chamber 200.
[0032] The drive shaft 21 is rotatably supported on the housing.
The drive shaft 21 is coupled to a crankshaft by way of a chain, a
gear or the like. The rotor 22 is fixed to the drive shaft 21 in
the circumferential direction. The rotor 22 has a columnar shape. A
surface of the rotor 22 on one side in the axial direction has a
recessed portion 221. A plurality of (seven) slits 222 extending in
the radial direction are formed in the rotor 22. Back pressure
chambers 223 are disposed on the inner side of the slits 222 in the
radial direction. The outer peripheral surface 220 of the rotor 22
has projecting portions 224 which protrude outward in the radial
direction. The slits 222 are open on the projecting portions 224.
The vanes 23 are accommodated in the slits 222. An annular member
230 is provided in the recessed portion 221. The outer peripheral
surface of the member 230 opposes the proximal ends of the
respective vanes 23. An inner peripheral surface 240 of the cam
ring 24 has a cylindrical shape. The outer periphery of the cam
ring 24 has four protrusions 241 to 244 which protrude outward in
the radial direction. The first sealing member 261 is mounted on
the first protrusion 241. The second sealing member 262 is mounted
on the second protrusion 242. The pin 27 is fitted in the third
protrusion 243. As viewed in the axial direction of the cam ring
24, the first protrusion 241 and the second protrusion 242 are
disposed on sides opposite to each other with respect to a straight
line passing through the axis of the pin 27 and a center 24P of the
inner peripheral surface 240 of the cam ring. One end of the spring
25 is mounted on the fourth protrusion 244.
[0033] On the inside of the pump accommodating chamber 200, a first
control chamber 291, a first control chamber 292, and a spring
accommodating chamber 293 are present between the housing and the
cam ring 24. The first control chamber 291 is formed of a space
defined between a portion of an outer peripheral surface 245 of the
cam ring 24 ranging from the first protrusion 241 (first sealing
member 261) to the third protrusion 243 (pin 27), and the inner
peripheral surface of the housing (pump accommodating chamber 200).
The first control chamber 291 is sealed by the first sealing member
261 and the pin 27. A first region 246 defined between the first
sealing member 261 and the pin 27 on the outer peripheral surface
245 of the cam ring faces the first control chamber 291. A second
control chamber 292 is formed of a space defined between a portion
of the outer peripheral surface 245 of the cam ring ranging from
the second protrusion 242 (second sealing member 262) to the third
protrusion 243 (pin 27), and the inner peripheral surface of the
housing (pump accommodating chamber 200). The second control
chamber 292 is sealed by the second sealing member 262 and the pin
27. A second region 247 defined between the second sealing member
262 and the pin 27 on the outer peripheral surface 245 of the cam
ring faces the second control chamber 292. The area of the second
region 247 (angle subtended by the second region 247 in the
circumferential direction of the cam ring 24) is slightly larger
than the area of the first region 246 (angle subtended by the first
region 246 in the circumferential direction of the cam ring 24).
The width in the radial direction of a portion of the cam ring 24
which corresponds to the second region 247 (the end surface in the
axial direction of the cam ring 24, the end surface being formed so
as to continue to the second region 247, and opposing the bottom
surface of the pump accommodating chamber 200) is larger than the
width in the radial direction of a portion of the cam ring 24 which
corresponds to the first region 246 (the end surface in the axial
direction of the cam ring 24, the end surface being formed so as to
continue to the first region 246, and opposing the bottom surface
of the pump accommodating chamber 200) in average at least in a
region which is disposed adjacent to the discharge port 204 in the
radial direction. The spring accommodating chamber 293 is formed of
a space defined between a portion of the outer peripheral surface
245 of the cam ring ranging from the first protrusion 241 (first
sealing member 261) to the second protrusion 242 (second sealing
member 262) via the fourth protrusion 244, and the inner peripheral
surface of the housing (pump accommodating chamber 200).
[0034] The spring 25 is a compression coil spring. One end of the
spring 25 is brought into contact with the surface of the fourth
protrusion 244 on one side in the circumferential direction of the
cam ring 24. The surface of the fourth protrusion 244 on the other
side in the circumferential direction of the cam ring 24 opposes
the inner peripheral surface of the pump accommodating chamber 200
(spring accommodating chamber 293), and is capable of coming into
contact with this inner peripheral surface. The other end of the
spring 25 is mounted on the inner peripheral surface of the pump
accommodating chamber 200 (spring accommodating chamber 293). The
spring 25 is in a compressed state. The spring 25 has a
predetermined set load in an initial state, and always biases the
fourth protrusion 244 to the other side in the circumferential
direction.
[0035] The control mechanism 3 includes the control passage 43 and
a control valve 7. As shown in FIG. 1, the control passage 43
includes a first feedback passage 431 and a second feedback passage
432. One end side of the first feedback passage 431 is branched
from the discharge passage 41. The other end of the first feedback
passage 431 is connected to the first control chamber 291. The
second feedback passage 432 includes a supply passage 433, a
communication passage 434, and a drainage passage 435. One end side
of the supply passage 433 is branched from the first feedback
passage 431. The other end of the supply passage 433 is connected
to the control valve 7. One end of the communication passage 434 is
connected to the control valve 7. The other end of the
communication passage 434 is connected to the second control
chamber 292. One end of the drainage passage 435 is connected to
the control valve 7. The other end of the drainage passage 435 is
connected to the oil pan 400.
[0036] As shown in FIG. 3, the control valve 7 is formed of an
electromagnetic valve (solenoid valve), and includes a valve
portion 8 and a solenoid portion 9. The valve portion 8 includes a
cylinder (cylindrical member) 80, a spool 81, and a spring (second
biasing member) 82. In FIG. 3, only the cylinder 80 is shown in
cross section. The solenoid portion 9 includes a casing 90, a
solenoid, a plunger, and a connector 92. The cylinder 80 is formed
of a hollow member (cylindrical member), an inner peripheral
surface 800 of which is cylindrical. One side of the cylinder 80 in
the axial direction is open, and the cylinder 80 has a bottom
portion 802 on the other side in the axial direction. A hole 809
penetrates the bottom portion 802 in the axial direction. The
cylinder 80 has a plurality of ports. These ports are holes which
penetrate the cylinder 80 in the radial direction, and each of
these ports is open on the inner peripheral surface 800 and an
outer peripheral surface 801 of the cylinder 80. These ports
function as portions of the second feedback passage 432 together
with the spaces on the inner peripheral side of the cylinder 80.
The plurality of ports include a supply port 803, a communication
port 804, and a drainage port 805. The supply port 803, the
communication port 804, and the drainage port 805 are arranged in
this order from one side to the other side in the axial direction
of the cylinder 80. The other end of the supply passage 433 is
connected to the supply port 803. The supply port 803 communicates
with the discharge opening 203 through the supply passage 433
(second feedback passage 432) and the discharge passage 41. The
supply port 803 allows working oil discharged through the discharge
opening 203 to be introduced into the cylinder 80. One end of the
communication passage 434 is connected to the communication port
804. The communication port 804 communicates with the second
control chamber 292 through the communication passage 434. The
communication port 804 allows the inside of the cylinder 80 and the
second control chamber 292 to communicate with each other. One end
of the drainage passage 435 is connected to the drainage port 805.
The drainage port 805 communicates with the oil pan 400 through the
drainage passage 435. The drainage port 805 can drain working oil
from the inside of the cylinder 80.
[0037] The spool 81 is a valve element (valve) provided in the
second feedback passage 432. The spool 81 is disposed in the
cylinder 80 (accommodated in the cylinder 80), and is reciprocable
in the axial direction of the cylinder 80 along the inner
peripheral surface 800 of the cylinder. The spool 81 includes a
first land portion 811, a second land portion 812, and a connecting
portion 813. The first land portion 811 is disposed at the end of
the spool 81 on one side in the axial direction. The second land
portion 812 is disposed at the end of the spool 81 on the other
side in the axial direction. The connecting portion 813 is disposed
between the first land portion 811 and the second land portion 812,
and connects both land portions 811, 812 with each other. The
diameter of the first land portion 811 and the diameter of the
second land portion 812 are equal to each other. The diameter of
both land portions 811, 812 is slightly smaller than the diameter
of the inner peripheral surface 800 of the cylinder. The connecting
portion 813 is formed of a thin shaft portion. The diameter of the
connecting portion 813 is smaller than the diameter of both land
portions 811, 812. The respective land portions 811, 812 is in
slide contact with the inner peripheral surface 800 of the
cylinder.
[0038] A space 807 is defined between the first land portion 811
and the second land portion 812 as a liquid chamber in the inside
of the cylinder 80. A space 808 is defined between the second land
portion 812 and the bottom portion 802. The space 807 is defined by
the inner peripheral surface 800 of the cylinder, the outer
peripheral surface of the connecting portion 813, the surface of
the first land portion 811 on the other side in the axial
direction, and the surface of the second land portion 812 on one
side in the axial direction. The space 807 has a cylindrical shape
(annular shape). The supply port 803 is open to the space 807 in
the initial state, and the communication port 804 is always open to
the space 807. The drainage port 805 may be open to the space 807.
On the inner peripheral side of the cylinder 80, the space 808 is
defined between the surface of the second land portion 812 on the
other side in the axial direction and the bottom portion 802. The
drainage port 805 is slightly open to the space 808 in the initial
state. The spring 82 is formed of a compression coil spring, and is
disposed in the space 808. The space 808 functions as a spring
chamber which accommodates the spring 82. One end side of the
spring 82 is fitted on the outer peripheral side of a projection
portion which projects from the second land portion 812 of the
spool 81, and one end of the spring 82 is in contact with the end
surface of the second land portion 812 on the other side. The other
end of the spring 82 is in contact with the bottom portion 802. The
spring 82 is in a compressed state. The spring 82 has a
predetermined set load in the initial state, and always biases the
spool 81 to one side in the axial direction. This spring force is
defined as fs.
[0039] The solenoid portion 9 is joined to one side of the valve
portion 8 in the axial direction, thus closing the opening of the
cylinder 80 on one side in the axial direction. The solenoid
portion 9 is an electromagnet which receives a supply of an
electric current through the connector 92. The solenoid and the
plunger are accommodated in the casing 90. The solenoid (coil)
generates an electromagnetic force when energized. The plunger
(armature) is made of a magnetic material, is disposed on the inner
peripheral side of the solenoid, and is movable in the axial
direction. The plunger is biased in the axial direction by an
electromagnetic force generated by the solenoid. The first land
portion 811 of the spool 81 is integrally joined to the plunger.
The above-mentioned electromagnetic force biases the first land
portion 811 (spool 81) to the other side in the axial direction.
This electromagnetic force (thrust of the solenoid for propelling
the spool 81) is assumed as "fm." The solenoid can continuously
change the magnitude of an electromagnetic force fm according to
the value of an electric current supplied. The solenoid portion 9
is subjected to a PWM control, and the current value of the
solenoid is given by a duty ratio D. An electromagnetic force fin
varies according to duty ratio D (the current value of the
solenoid). When a duty ratio D is less than a predetermined value
D1 (dead zone), an electromagnetic force fm assumes zero, which is
the minimum value (the electromagnetic force is not generated),
regardless of the magnitude of the duty ratio D. When a duty ratio
D is equal to or more than the predetermined value D1 and less than
a predetermined value D2, an electromagnetic force fm varies
according to the duty ratio D. With a larger duty ratio D, the
electromagnetic force fm increases more. When a duty ratio D is
equal to or more than the predetermined value D2, an
electromagnetic force fin assumes the maximum value fmax regardless
of the magnitude of the duty ratio D.
[0040] The pressure sensor 51 detects (measures) the pressure of
working oil discharged through the discharge opening 203 of the
pump 2 to the discharge passage 41. In other words, the pressure
sensor 51 detects (measures) the pressure in the main gallery 42
(main gallery hydraulic pressure P). The rotational speed sensor 52
detects (measures) the rotational speed Ne of the engine
(crankshaft).
[0041] The engine control unit (hereinafter, ECU) 6 controls the
opening/closing of the control valve 7 (that is, the discharge
amount of the pump 2) based on inputted information and an
incorporated program. With such control, the pressure and flow rate
of working oil to be supplied to the engine are controlled. The ECU
6 includes a reception portion, a central processing unit (CPU), a
read only memory (ROM), a random access memory (RAM), and a drive
circuit. The ECU 6 includes, as a main component, a microcomputer
where these components are connected with each other through
bidirectional common buses. The reception portion receives detected
values of the pressure sensor 51 and the rotational speed sensor
52, and other information about engine operation conditions (oil
temperature, water temperature, engine load and the like). The ROM
is a memory portion which stores control programs, map data and the
like. The CPU is an arithmetic operation portion which performs an
arithmetic operation using the information inputted from the
reception portion based on a control program which is read out. The
CPU performs arithmetic operations for values, such as an electric
current to be supplied to the control valve 7 (solenoid portion 9).
The CPU outputs a control signal which corresponds to the result of
the arithmetic operation to the drive circuit. The drive circuit
controls an electric current to be supplied to the solenoid such
that the drive circuit supplies electric power to the solenoid in
response to the control signal outputted from the CPU. The drive
circuit is a PWM control circuit, and causes the pulse width (duty
ratio D) of a signal for driving the solenoid to be varied in
response to the control signal.
[0042] During the operation of the engine, the control program is
performed so that the control valve 7 (pump 2) is controlled. The
ECU 6 causes a value (duty ratio D) of an electric current to be
supplied to the solenoid to be varied such that the difference
between a main gallery hydraulic pressure P and a predetermined
required value P* falls within a predetermined range at any engine
speed Ne within a predetermined range of rotational speed of the
engine (Ne.gtoreq.Ne1). Ne1 is a rotational speed which is set in
advance. The required value P* is a hydraulic pressure, such as a
hydraulic pressure required for operating the variable valve
device, a hydraulic pressure required by an oil jet for cooling an
engine piston, or a hydraulic pressure required for lubricating a
bearing of the crankshaft. The required value P* is set in advance
as an ideal value which corresponds to an engine operation
condition, such as an engine speed Ne. The ROM of the ECU 6 stores,
in the form of a map, required values P* for respective engine
speeds Ne (according to the engine operation conditions). The map
may set a discharge pressure, an oil temperature, a water
temperature, an engine load and the like as parameters, for
example. The ECU 6 causes a duty ratio D to be varied according to
an engine speed Ne based on the map. The ECU 6 detects a main
gallery hydraulic pressure P, and performs feedback control so as
to cause the main gallery hydraulic pressure P to approximate a
required value P*. The ECU 6 causes a duty ratio D to be varied
such that the difference between the detected value and the
required value P* for the main gallery hydraulic pressure P falls
within a predetermined range. When an engine speed Ne is less than
Ne1, the ECU 6 sets a duty ratio D to zero. When an engine speed Ne
detected (measured) by a rotational speed sensor 52 is equal to or
more than Ne1, the ECU 6 calculates the difference .DELTA.P (=P*-P)
between a hydraulic pressure P detected (measured) by a pressure
sensor 51 and a required value P* at the above-mentioned (any)
rotational speed Ne detected. When the magnitude of the difference
.DELTA.P is larger than a value .DELTA.Pset set in advance, a duty
ratio D is caused to be varied such that the magnitude of the
difference .DELTA.P is reduced until the magnitude of the
difference .DELTA.P becomes equal to or less than the value
.DELTA.Pset. When the magnitude of the difference .DELTA.P is equal
to or less than the value .DELTA.Pset, a duty ratio D is maintained
(at a value immediately before a value at which the magnitude of
the difference .DELTA.P becomes equal to or less than the value
.DELTA.Pset).
[0043] Next, the manner of operation is described. The cam ring 24
accommodates the rotor 22 and the plurality of vanes 23 so that a
plurality of pump chambers (working chambers) 28 are defined. The
rotor 22 and the plurality of vanes 23 function as elements (pump
structures) which constitute the pump 2. Each working chamber 28 is
formed (defined) by the outer peripheral surface 220 of the rotor
22, two vanes 23 disposed adjacent to each other, the inner
peripheral surface 240 of the cam ring, the bottom surface of the
pump accommodating chamber 200, and the side surface of the cover.
The volume of each of the working chambers 28 is variable with the
rotation. The volume of each working chamber 28 increases and
decreases with the rotation and hence, the plurality of working
chambers 28 function as a pump. Within a range which overlaps with
the intake port 202 (intake region), the volume of the working
chamber 28 increases according to the rotation, and the working
chamber 28 takes in working oil through the intake port 202. Within
a range which overlaps with the discharge port 204 (discharge
region), the volume of the working chamber 28 decreases, and the
working chamber 28 discharges working oil to the discharge port
204. The theoretical discharge amount (a discharge amount per one
rotation), that is capacity, of the pump 2 is determined by the
difference between the maximum volume and the minimum volume of the
working chamber 28. The rotation of the crankshaft is transmitted
to the drive shaft 21 of the pump 2 by way of the chain and the
gear. The drive shaft 21 rotationally drives the rotor 22. The
rotor 22 rotates in the counterclockwise direction in FIG. 2. When
the pump structures including the rotor 22 are rotationally driven,
working oil, which is introduced through the intake opening 201, is
discharged through the discharge opening 203. A discharge pressure
is introduced into the back pressure chambers 223, and pushes out
the vanes 23 from the slits 222, thus improving liquid tightness of
the working chambers 28. Also in the case where an engine speed is
low so that a centrifugal force and a pressure in the back pressure
chambers 223 are low, the annular member 230 pushes out the vanes
23 from the slits 222, thus improving the liquid tightness of the
working chambers 28. The pump 2 sucks working oil from the oil pan
400 through the intake passage 40, and discharges the working oil
to the discharge passage 41. The pump 2 pressure-feeds working oil
to respective portions of the engine through the discharge passage
41 and the main gallery 42. When the pressure (discharge pressure)
in the discharge passage 41 assumes a predetermined high pressure,
the relief valve 440 opens so as to drain working oil through the
relief passage 44 from the discharge passage 41.
[0044] The amount of variation in the volume of the working chamber
28 (the difference between the maximum volume and the minimum
volume) is variable. The cam ring 24 is a member which is movable
(movable member) in the pump accommodating chamber 200, and the cam
ring 24 can perform a rotational oscillation about the pin 27. The
pin 27 functions as a pivot portion (fulcrum) disposed in the pump
accommodating chamber 200. The cam ring 24 performs a rotational
oscillation so that the difference (amount of eccentricity .DELTA.)
between the axis (center of rotation) 22P of the rotor 22 and the
axis (center) 24P of the inner peripheral surface 240 of the cam
ring varies. Varying the amount of eccentricity .DELTA. varies the
amount of increase or decrease in volume (amount of variation in
volume) of each of the plurality of working chambers 28 at the time
of rotating the rotor 22 and the plurality of vanes 23. That is,
the pump 2 is a variable capacity pump. Accordingly, increasing the
amount of eccentricity .DELTA. allows capacity to be increased, and
reducing the amount of eccentricity .DELTA. allows capacity to be
decreased. Further, the volume of the first control chamber 291 and
the volume of the second control chamber 292 can be varied with the
movement of the cam ring 24.
[0045] The cam ring 24 is biased by the spring 25 to one side (to
the side where the amount of increase or decrease in volume of each
of the plurality of working chambers 28 increases, and the amount
of eccentricity .DELTA. increases) in the rotational direction
about the pin 27. This spring force is defined as "Fs." The cam
ring 24 receives the pressure of working oil in the first control
chamber 291. The first region 246 of the outer peripheral surface
245 of the cam ring functions as a pressure receiving surface which
receives a pressure in the first control chamber 291. The cam ring
24 is biased to the other side (to the side where the amount of
eccentricity .DELTA. decreases) in the rotational direction about
the pin 27 by the above-mentioned hydraulic pressure. A force
generated by this hydraulic pressure (hydraulic pressure force) is
defined as "Fp1." The volume of the first control chamber 291
increases with the movement of the cam ring 24 to the other side
(the direction opposing the biasing force Fs of the spring 25) in
the above-mentioned rotational direction. The cam ring 24 receives
the pressure (control hydraulic pressure) p of working oil in the
second control chamber 292. The second region 247 of the outer
peripheral surface 245 of the cam ring functions as a pressure
receiving surface which receives a control hydraulic pressure p.
The cam ring 24 is biased to one side in the above-mentioned
rotational direction by the control hydraulic pressure p. A force
generated by the control hydraulic pressure p (hydraulic pressure
force) is defined as "Fp2." The volume of the second control
chamber 292 increases with the movement of the cam ring 24 to one
side (the same direction as the biasing force Fs) in the
above-mentioned rotational direction. The position of the cam ring
24 in the rotational direction (the amount of eccentricity .DELTA.,
that is, capacity) is mainly determined by hydraulic pressure force
Fp1, hydraulic pressure force Fp2, and biasing force Fs. When a
hydraulic pressure force Fp1 becomes larger than the sum of
hydraulic pressure force Fp2 and biasing force Fs (Fp2+Fs), the cam
ring 24 oscillates to the other side in the above-mentioned
rotational direction so that the amount of eccentricity .DELTA.
(capacity) reduces. When a hydraulic pressure force Fp1 becomes
smaller than the sum of hydraulic pressure force Fp2 and biasing
force Fs (Fp2+Fs), the cam ring 24 oscillates to one side in the
above-mentioned rotational direction so that the amount of
eccentricity .DELTA. (capacity) increases.
[0046] Working oil discharged through the discharge opening 203
(hydraulic pressure P of the main gallery 42) is introduced into
the first control chamber 291 through the first feedback passage
431. Working oil discharged through the discharge opening 203 (main
gallery hydraulic pressure P) may be introduced into the second
control chamber 292 through the second feedback passage 432 (the
supply passage 433, the control valve 7, and the communication
passage 434). Working oil in the second control chamber 292 may be
drained through the drainage passage 435. The control valve 7 can
control an introduction of working oil into the second control
chamber 292 and drainage of working oil from the second control
chamber 292. The spool 81 moves so as to switch the connection
state of the passage. To be more specific, the first land portion
811 causes the opening area of the supply port 803 to be varied,
and the second land portion 812 causes the opening area of the
drainage port 805 to be varied. The opening of the communication
port 804 is not closed by either land portion. The space 807 forms
a passage for working oil. Moving the spool 81 switches between
establishing and shutting off of the connection between the
communication passage 434 and the supply passage 433, or switches
between establishing and shutting off of the connection between the
communication passage 434 and the drainage passage 435. In
performing switching, it is assumed as a basic mode that the
communication passage 434 communicates with both of the supply
passage 433 and the drainage passage 435. To be more specific, in a
state where the first land portion 811 partially closes the opening
of the supply port 803 which is open to the space 807, the second
land portion 812 causes the drainage port 805 to be open to the
space 807. In a state where the second land portion 812 partially
closes the opening of the drainage port 805 which is open to the
space 807, the first land portion 811 causes the supply port 803 to
be open to the space 807. The opening of the communication port
804, which is open to the space 807, is always fully open. In
performing switching, it is sufficient to have a state where the
supply port 803 and the drainage port 805 are simultaneously open
to the space 807 (temporarily at a predetermined position of the
spool 81). It is not necessary to have a state where the maximum
opening area of the supply port 803, which is open to the space
807, and the maximum opening area of the drainage port 805, which
is open to the space 807, are equal to each other. Further, it is
not necessary that the position of the spool at which the opening
area of the supply port 803, which is open to the space 807, starts
to decrease be to the same as the position of the spool at which
the drainage port 805 starts to become open to the space 807. It is
not also necessary that the position of the spool at which the
opening area of the drainage port 805, which is open to the space
807, starts to decrease be to the same as the position of the spool
at which the supply port 803 starts to become open to the space
807. These cases are determined by tuning.
[0047] The spool 81 switches the connection state of the passage,
thus switching between establishing and shutting off of the
communication between the discharge opening 203 and the second
control chamber 292 (through the communication passage 434 and the
supply passage 433) and, switching between establishing and
shutting off of the communication between the second control
chamber 292 and the oil pan 400 (through the communication passage
434 and the drainage passage 435). As shown in FIG. 4, when the
spool 81 is at an initial position, the communication passage 434
and the supply passage 433 are connected with each other without
any limitation (with the maximum cross-sectional area of the flow
passage). The discharge opening 203 and the second control chamber
292 are in a state of maximum communication with each other so that
the amount of working oil which is discharged from the discharge
opening 203 and may be introduced into the second control chamber
292 becomes the maximum. Further, the communication passage 434 and
the drainage passage 435 are connected with each other with the
maximum limitation (with the minimum cross-sectional area of the
flow passage). The second control chamber 292 and the oil pan 400
are in a state of minimum communication with each other so that the
amount of working oil which may be drained from the inside of the
second control chamber 29 becomes the minimum. To be more specific,
both passages 434, 435 are shut off so that the second control
chamber 292 and the oil pan 400 are in a state of non-communication
with each other whereby working oil is not drained from the inside
of the second control chamber 29. Hereinafter, such a state is
referred to as "first state." As shown in FIG. 5, when the spool 81
slightly moves to the other side in the axial direction from the
initial position, the communication passage 434 and the drainage
passage 435 are connected with each other with a limitation (with a
cross-sectional area of the flow passage which is below maximum).
The second control chamber 292 and the oil pan 400 are brought into
a state of partially communicating with each other so that working
oil may be drained from the inside of the second control chamber
292. Further, the communication passage 434 and the supply passage
433 are connected with each other with a limitation. The discharge
opening 203 and the second control chamber 292 are in a state of
partially communicating with each other so that working oil
discharged from the discharge opening 203 may be introduced into
the second control chamber 292. Hereinafter, such a state is
referred to as "second state."
[0048] As shown in FIG. 6, when the spool 81 moves from the initial
position to the other side in the axial direction by a distance
larger than the distance for the second state, the communication
passage 434 and the drainage passage 435 are connected with each
other with a smaller limitation. The second control chamber 292 and
the oil pan 400 are brought into a state of communicating with each
other with a larger cross-sectional area of the flow passage so
that the amount of working oil which may be drained from the inside
of the second control chamber 292 increases. Further, the
communication passage 434 and the supply passage 433 are connected
with each other with a larger limitation. The discharge opening 203
and the second control chamber 292 are brought into a state of
communicating with each other with a smaller cross-sectional area
of the flow passage so that the amount of working oil which is
discharged from the discharge opening 203 and may be introduced
into the second control chamber 292 decrease. Hereinafter, such a
state is referred to as "third state." When the spool 81 moves from
the initial position to the other side in the axial direction by a
predetermined distance or more, the communication passage 434 and
the drainage passage 435 are connected with each other without any
limitation. The second control chamber 292 and the oil pan 400 are
brought into a state of maximum communication with each other so
that the amount of working oil which may be drained from the inside
of the second control chamber 292 becomes the maximum. Further, the
communication passage 434 and the supply passage 433 are connected
with each other with the maximum limitation. The discharge opening
203 and the second control chamber 292 are in a state of minimum
communication with each other so that the amount of working oil
which is discharged from the discharge opening 203 and may be
introduced into the second control chamber 292 becomes the minimum.
To be more specific, both passages 433, 434 are shut off so that
the discharge opening 203 and the second control chamber 292 are in
a state of non-communication with each other whereby working oil is
not introduced into the second control chamber 29. Hereinafter,
such a state is referred to as "fourth state."
[0049] The solenoid portion 9 can move the spool 81 to any position
in response to a control signal (duty ratio D). The position of the
spool 81 is proportional to a duty ratio D on average. The control
valve 7 functions as a proportional control valve. The control
valve 7 can continuously change the position of the spool 81, and
can also stop the spool 81 at any position. The position of the
spool 81 in the axial direction with respect to the cylinder 80 is
mainly determined by a spring force fs and an electromagnetic force
fm. The solenoid can continuously change an electromagnetic force
fm. Changing the magnitude of electromagnetic force fm allows the
spool 81 to move, in other words, allows a transition between the
above-mentioned states (state transition). When an electromagnetic
force fm becomes larger than a spring force fs, the spool 81 moves
to the other side in the axial direction, thus realizing a state
transition from the first state toward the fourth state. When an
electromagnetic force fm becomes smaller than a spring force fs,
the spool 81 moves to one side in the axial direction, thus
realizing a state transition from the fourth state toward the first
state. An electromagnetic force fm varies according to a duty ratio
D. The solenoid functions as a proportional electromagnet which can
continuously control an electromagnetic force fm according to a
duty ratio D (current value). Basically, an electromagnetic force
fm increases when a duty ratio D is increased. The position of the
spool 81 (land portions 811, 812) is determined according to a duty
ratio D. As shown in FIG. 7, the opening area Si of the supply port
803, which is open to the space 807, and the opening area Sd of the
drainage port 805, which is open to the space 807, are respectively
proportional to a duty ratio D. When a duty ratio D is less than a
predetermined value Ds, the opening area Si assumes the maximum
value Smax regardless of the magnitude of the duty ratio D. When a
duty ratio D is equal to or more than the predetermined value Ds
and less than a predetermined value De, the opening area Si varies
according to the duty ratio D so that the opening area Si becomes
smaller with a corresponding larger duty ratio D. When a duty ratio
D is equal to or more than the predetermined value De, the opening
area Si assumes the minimum value Smin (zero in this embodiment)
regardless of the magnitude of the duty ratio D. When a duty ratio
D is less than the predetermined value Ds, the opening area Sd
assumes the minimum value Smin (zero in this embodiment) regardless
of the magnitude of the duty ratio D. When a duty ratio D is equal
to or more than the predetermined value Ds and less than the
predetermined value De, the opening area Sd varies according to the
duty ratio D so that the opening area Sd becomes larger with a
corresponding larger duty ratio D. When a duty ratio D is equal to
or more than the predetermined value De, the opening area Sd
assumes the maximum value Smax regardless of the magnitude of the
duty ratio D. Respective values of the predetermined value Ds, the
predetermined value De, the minimum value Smin, and the maximum
value Smax associated with the opening area Si may be different
from the respective values associated with the opening area Sd. A
predetermined value De at which an opening area Si assumes the
minimum value Smin is larger than the predetermined value Ds at
which an opening area Sd assumes the minimum value Smin. That is,
an opening area Si and an opening area Sd intersect with each other
between the predetermined value Ds and the predetermined value
De.
[0050] The description is made with respect to the operation of the
control valve 7 according to the variation in thrust fm of the
solenoid (duty ratio D) and the operation of the cam ring 24 which
is caused with this operation of the control valve 7. In FIG. 4 to
FIG. 6, a spring force fs acts on the spool 81 in the leftward
direction, and a thrust fm acts on the spool 81 in the rightward
direction. When a duty ratio D is less than the predetermined value
Ds, and a thrust fm is equal to or less than a spring force fs (set
load of the spring 82), as shown in FIG. 4, the spool 81 is at an
initial position where the spool 81 is moved to the position
closest to one side in the axial direction. The opening area Si of
the supply port 803, which is open to the space 807, assumes the
set maximum value Smax. On the other hand, the opening of the
drainage port 805, which is open to the space 807, is completely
closed by the second land portion 812 so that the opening area Sd
assumes the set minimum value Smin (zero). The hydraulic pressure P
introduced into the space 807 from the supply passage 433 is
introduced into the second control chamber 292 without a pressure
loss. The space 807 functions as a communication chamber where
working oil flows through. The sum of hydraulic pressure force Fp2
and biasing force Fs (Fp2+Fs (the set load of the spring 25)) is
larger than the hydraulic pressure force Fp1 which acts on the cam
ring 24. Accordingly, the cam ring 24 is at a position where the
cam ring 24 oscillates the most to one side in the rotational
direction, thus maintaining the maximum amount of eccentricity
.DELTA..
[0051] When a duty ratio D is equal to or more than the
predetermined value Ds and less than the predetermined value De,
and a thrust fm is larger than a spring force fs (set load of the
spring 82), as shown in FIG. 5, the spool 81 slightly moves to the
other side in the axial direction from the initial position. The
opening of the supply port 803, which is open to the space 807, is
partially closed by the first land portion 811 so that the opening
area Si becomes smaller than the maximum value Smax. On the other
hand, the second land portion 812 also moves and hence, the
drainage port 805 becomes partially open to the space 807 whereby
the opening area Sd becomes larger than the minimum value Smin
(zero). That is, connection destination of the communication
passage 434 (second control chamber 292) is switched from only the
supply port 803 to both of the supply port 803 and the drainage
port 805. Working oil is drained from the space 807 through the
drainage passage 435. Accordingly, working oil may be drained from
the communication passage 434 (second control chamber 292) via the
space 807. Further, working oil may also be drained from the supply
passage 433 via the space 807, thus generating a flow of working
oil toward the space 807 from the supply passage 433 through the
supply port 803. In this flow, the supply port 803 with the
decreased opening area Si functions as an orifice so that a
hydraulic pressure in the space 807 becomes lower than a hydraulic
pressure P in the supply passage 433. Accordingly, a pressure which
is reduced to a value lower than the hydraulic pressure P is
introduced into the second control chamber 292 from the space 807
and hence, a control hydraulic pressure p drops. The sum of force
Fp2 and biasing force Fs (Fp2+Fs) which act on the cam ring 24
becomes smaller than a force Fp1 and hence, the cam ring 24
oscillates to the other side in the rotational direction so that
the amount of eccentricity .DELTA. decreases. When the amount of
eccentricity .DELTA. (capacity) decreases, a discharge flow rate
decreases so that a main gallery hydraulic pressure P drops.
[0052] When a duty ratio D further increases in a range where the
duty ratio D is less than the predetermined value De, a thrust fm
further increases so that, as shown in FIG. 6, the spool 81 further
moves to the other side in the axial direction. The opening area Si
further decreases, thus approximating the minimum value Smin. On
the other hand, the opening area Sd further increases, thus
approximating the maximum value Smax. An increase in the opening
area Sd increases the amount of working oil drained from the space
807 through the drainage passage 435. Accordingly, the amount of
working oil which may be drained from the communication passage 434
(second control chamber 292) via the space 807 increases. Further,
a decrease in the opening area Si causes the orifice diameter of
the supply port 803 to decrease so that a hydraulic pressure in the
space 807 becomes further lower than a hydraulic pressure P in the
supply passage 433. Accordingly, a control hydraulic pressure p
further drops. The sum of force Fp2 and biasing force Fs (Fp2+Fs)
which act on the cam ring 24 further decreases so that an amount of
eccentricity .DELTA. further decreases.
[0053] As described above, the control valve 7 changes a control
hydraulic pressure p and an amount of eccentricity .DELTA.
(capacity) by changing the position of the spool 81 according to a
duty ratio D. With such a change, the control valve 7 can control a
hydraulic pressure P and a discharge flow rate. As shown in FIG. 8,
when a duty ratio D is less than the predetermined value Ds, a
control hydraulic pressure p assumes the maximum value pmax (which
corresponds to a main gallery hydraulic pressure P) regardless of
the magnitude of the duty ratio D. When a duty ratio D is equal to
or more than the predetermined value Ds and less than the
predetermined value De, a control hydraulic pressure p varies
according to the duty ratio D so that the control hydraulic
pressure p becomes smaller with a corresponding larger duty ratio
D. When a duty ratio D is equal to or more than the predetermined
value De, a control hydraulic pressure p assumes the minimum value
pmin regardless of the magnitude of the duty ratio D. As shown in
FIG. 9, when a duty ratio D is less than the predetermined value
Ds, an amount of eccentricity .DELTA. assumes the maximum value
.DELTA.max regardless of the magnitude of the duty ratio D. When a
duty ratio D is equal to or more than the predetermined value Ds
and less than the predetermined value De, an amount of eccentricity
.DELTA. varies according to the duty ratio D so that the amount of
eccentricity .DELTA. becomes smaller with a corresponding larger
duty ratio D. When a duty ratio D is equal to or more than the
predetermined value De, an amount of eccentricity .DELTA. assumes
the minimum value .DELTA.min regardless of the magnitude of the
duty ratio D. As shown in FIG. 10, when a duty ratio D is less than
the predetermined value Ds, a main gallery hydraulic pressure P
assumes the maximum value Pmax (with an engine speed Ne at that
time) regardless of the magnitude of the duty ratio D. When a duty
ratio D is equal to or more than the predetermined value Ds and
less than the predetermined value De, a main gallery hydraulic
pressure P varies according to the duty ratio D so that the main
gallery hydraulic pressure P becomes smaller with a corresponding
larger duty ratio D. When a duty ratio D is equal to or more than
the predetermined value De, a main gallery hydraulic pressure P
assumes the minimum value Pmin (with an engine speed Ne at that
time) regardless of the magnitude of the duty ratio D.
[0054] The ECU 6 causes a duty ratio D to be varied according to
the stored map such that, within a range where an engine speed Ne
is equal to or more than Ne1, the difference .DELTA.P between the
detected value and a required value P* for the main gallery
hydraulic pressure P falls within a predetermined range. With such
a variation, it is possible to realize a characteristic of a
hydraulic pressure P with respect to an engine speed Ne as
indicated by a bold solid line in FIG. 11. The description is made
by taking a low rotational speed range of an engine as an example.
As shown in FIG. 12, the ECU 6 causes a duty ratio D to assume 0%
(an electric current is not supplied to the solenoid) within a
range where an engine speed Ne is less than Ne1. Working oil
discharged from the discharge opening 203 is introduced into the
second control chamber 292. However, working oil is not drained
from the second control chamber 292 to the oil pan 400.
Accordingly, working oil can be discharged from the discharge
opening 203 in a state where an amount of eccentricity .DELTA.
assumes the maximum value .DELTA.max. A main gallery hydraulic
pressure P (discharge flow rate) varies according to an engine
speed Ne at a constant gradient which corresponds to the maximum
capacity. Therefore, after the engine is started, it is possible to
cause a main gallery hydraulic pressure P to rapidly rise (it is
possible to ensure operational responsiveness of the variable valve
device, for example) according to an increase in the engine speed
Ne. In a range where an engine speed Ne is equal to or more than
Ne1 and less than Ne2, the magnitude of the difference .DELTA.P is
larger than a value .DELTA.Pset so that the ECU 6 causes a duty
ratio D to increase according to an increase in the engine speed
Ne. The amount of eccentricity .DELTA. (capacity) decreases
according to an increase in the duty ratio D. An increase in the
main gallery hydraulic pressure P caused by an increase in the
engine speed Ne is suppressed by a decrease in the amount of
eccentricity .DELTA.. In the same manner, by causing a duty ratio D
to decrease corresponding to a decrease in the engine speed Ne, a
decrease in the main gallery hydraulic pressure P can be suppressed
by an increase in the amount of eccentricity .DELTA.. Accordingly,
a main gallery hydraulic pressure P is maintained (controlled at a
fixed value) at P1 or around P1 regardless of engine speed Ne.
Therefore, it is possible to decrease the difference .DELTA.P by
making a main gallery hydraulic pressure P approximate a required
value P*. As described above, in the case where an engine speed Ne
is equal to or more than Ne1, when the difference .DELTA.P is
larger than a value .DELTA.Pset, the ECU 6 causes an amount of
working oil which is drained from the second control chamber 292 to
the oil pan 400 to be varied while allowing working oil to be
introduced into the second control chamber 292 until the difference
.DELTA.P becomes equal to or less than a value .DELTA.Pset. In a
range where an engine speed Ne is equal to or more than Ne2 and
less than Ne3, the magnitude of the difference .DELTA.P is equal to
or less than a value .DELTA.Pset and hence, the ECU 6 maintains a
duty ratio D at D3 (which is a value immediately before a value at
which the magnitude of the difference .DELTA.P becomes equal to or
less than the value .DELTA.Pset). A main gallery hydraulic pressure
P varies according to the engine speed Ne at a constant gradient
corresponding to a capacity which corresponds to D3. A main gallery
hydraulic pressure P rises (drops) corresponding to an increase
(decrease) in engine speed Ne. In a range where an engine speed Ne
is equal to or more than Ne3, the magnitude of the difference
.DELTA.P is larger than a value .DELTA.Pset and hence, in the same
manner as the range where an engine speed Ne is equal to or more
than Ne1 and less than Ne2, the ECU 6 causes a duty ratio D to
increase (decrease) according to an increase (decrease) in the
engine speed Ne. Accordingly, a main gallery hydraulic pressure P
is maintained (controlled at a fixed value) at P2 or around P2
regardless of engine speed Ne. This operation is repeated plurality
of times according to variation in engine speed Ne, thus realizing
the above-mentioned characteristic having a stairs-like shape.
[0055] The solenoid can change, according to duty ratio D (the
value of an electric current supplied), the magnitude of an
electromagnetic force fm which biases the spool 81 in the axial
direction. Accordingly, varying duty ratio D according to engine
speed Ne allows main gallery hydraulic pressure P and discharge
flow rate to be freely varied (controlled). Characteristics of main
gallery hydraulic pressure P and discharge flow rate with respect
to engine speed Ne can be easily caused to approximate desired
characteristics. Accordingly, power loss caused due to unnecessary
rise in discharge pressure (increase in flow rate) can be
suppressed so that fuel economy can be improved. In the
above-mentioned description, characteristic is described to have a
stairs-like shape for facilitating understanding of the
description. However, in an actual control, numerous number of
stairs may be formed, that is, main gallery hydraulic pressure P
may be steplessly controlled according to an engine speed Ne, thus
approximately continuously controlling the main gallery hydraulic
pressure P according to required hydraulic pressure P*. A main
gallery hydraulic pressure P is feedback controlled according to a
differential pressure .DELTA.P and hence, the control valve 7 and
the cam ring 24 are operated such that the characteristic of a
discharge pressure P which corresponds to the variation in engine
speed Ne approximates a required characteristic. With such feedback
control, while the pump 2 is prevented from being affected by
leakage (leakage of working oil) or the like caused by a clearance
formed between members, the characteristic of a hydraulic pressure
P can be accurately controlled. A method for feedback controlling a
hydraulic pressure P to a required value P* is not limited to the
above-mentioned method, and any method may be adopted. Setting a
value .DELTA.Pset to a smaller value allows steps of a stairs-like
shape to continuously change more finely. A value .DELTA.Pset may
be set to zero. Hunting in control can be suppressed by setting a
value .DELTA.Pset to a value other than zero, and by preventing a
duty ratio D from being varied when the magnitude of difference
.DELTA.P is equal to or less than the value .DELTA.Pset.
[0056] The control valve 7 can continuously change the position of
the spool 81. Accordingly, the control valve 7 can move the spool
81 to any position, thus controlling a control hydraulic pressure
p, an amount of eccentricity .DELTA. (capacity), and a main gallery
hydraulic pressure P to any values. The control valve 7 can stop
the spool 81 at any position. Accordingly, the control valve 7 can
fix the spool 81 at any position, thus fixing a control hydraulic
pressure p and an amount of eccentricity .DELTA. (capacity) at any
values. Therefore, the control valve 7 can realize control to fix a
gradient when a hydraulic pressure P rises or drops according to a
variation in engine speed Ne.
[0057] The control valve 7 includes the solenoid portion 9 which is
capable of generating an electromagnetic force fm for biasing the
spool 81. Accordingly, the spool 81 can be moved to any position by
the solenoid portion 9. The spool 81 is integrally coupled with the
plunger of the solenoid portion 9. Therefore, even if a force
generated by a hydraulic pressure acts on the spool 81 from one
side or the other side in the axial direction, it is possible to
prevent the spool 81 from being moved. With such a configuration, a
control hydraulic pressure p, an amount of eccentricity .DELTA.,
and a hydraulic pressure P are prevented from being easily affected
by disturbances and hence, ease of control can be improved. A
control hydraulic pressure p, an amount of eccentricity .DELTA.,
and a hydraulic pressure P are controlled by opening/closing the
port of the control valve 7 and hence, the control is not affected
by the spring constant of the spring 25 of the cam ring 24.
[0058] The control valve 7 is provided in the second feedback
passage 432. With the movement of the spool 81, the control valve 7
varies the cross-sectional area Sd of the flow passage, through
which working oil in the second control chamber 292 is drained to
the oil pan 400, while making the discharge opening 203 and the
second control chamber 292 communicate with each other. By varying
the cross-sectional area Sd of the flow passage as described above,
the drainage amount of working oil from the space 807 (second
control chamber 292) is varied (adjusted). With such variation, a
control hydraulic pressure p is varied (controlled), thus
controlling the amount of eccentricity .DELTA. (capacity) and a
main gallery hydraulic pressure P. In this embodiment,
simultaneously with the variation in the cross-sectional area Sd,
the discharge opening 203 and the space 807 (second control chamber
292) are made to communicate with each other. Accordingly, the
drainage amount of working oil from the second control chamber 292
varies slowly with respect to the movement of the spool 81.
Therefore, a control hydraulic pressure p, an amount of
eccentricity .DELTA. (capacity), and a main gallery hydraulic
pressure P vary slowly with respect to variation in duty ratio D
(the movement amount of the spool 81) (the rapid operation of the
cam ring 24 is suppressed). As a result, ease of control of a main
gallery hydraulic pressure P is improved.
[0059] With the movement of the spool 81 to the other side in the
axial direction (in the first direction), the control valve 7
increases the cross-sectional area Sd of the flow passage, through
which working oil in the second control chamber 292 is drained to
the oil pan 400, while decreasing the cross-sectional area Si of
the flow passage, through which working oil is introduce from the
discharge opening 203 to the second control chamber 292.
Accordingly, the discharge opening 203 and the space 807 (second
control chamber 292) are made to communicate with each other
simultaneously with an increase in the cross-sectional area Sd and
hence, a drainage amount from the second control chamber 292
increases slowly with respect to the movement of the spool 81.
Accordingly, it is possible to cause the falling gradient of a
hydraulic pressure P to slowly decrease with respect to a variation
(increase) in duty ratio D. Further, the orifice diameter of the
supply port 803 decreases with a decrease in the opening area Si.
That is, the supply port 803 functions as a variable orifice. For
this reason, it is possible to cause a hydraulic pressure in the
space 807 (that is, a control hydraulic pressure p) to drop
sufficiently with respect to a hydraulic pressure P in the supply
passage 433 without significantly increasing the drainage amount
from the space 807. Accordingly, an increase in drainage amount can
be suppressed, thus suppressing lowering of efficiency of the pump
2. Further, an opening area Si is decreased in increasing a
drainage amount from the second control chamber 292 so that an
amount of working oil which can be introduced into the second
control chamber 292 decreases. Therefore, it is possible to cause a
control hydraulic pressure p to drop sufficiently when desired and
hence, a range (lower limit) of a control hydraulic pressure p can
be expanded. For this reason, ease of control is improved.
[0060] With the movement of the spool 81 to one side in the axial
direction (in a second direction), the control valve 7 decreases
the cross-sectional area Sd of the flow passage while increasing
the cross-sectional area Si of the flow passage. Accordingly, the
discharge opening 203 and the space 807 (second control chamber
292) are made to communicate with each other simultaneously with a
decrease in the cross-sectional area Sd and hence, a drainage
amount from the second control chamber 292 decreases slowly with
respect to the movement of the spool 81. Accordingly, it is
possible to cause the rising gradient of a hydraulic pressure P to
slowly increase with respect to a variation (decrease) in duty
ratio D. Further, an opening area Si is increased in decreasing a
drainage amount from the second control chamber 292 so that an
amount of working oil which can be introduced into the second
control chamber 292 increases. Therefore, it is possible to cause a
control hydraulic pressure p to sufficiently rise when desired and
hence, a range (upper limit) of a control hydraulic pressure p can
be expanded. In other words, when the amount of working oil which
is discharged from the discharge opening 203 and introduced into
the second control chamber 292 increases, a control mechanism 3
decreases the amount of working oil drained from the inside of the
second control chamber 292. When the amount of working oil which is
discharged from the discharge opening 203 and introduced into the
second control chamber 292 decreases, the control mechanism 3
increases the amount of working oil drained from the inside of the
second control chamber 292. Accordingly, it becomes possible to
vary (control) a control hydraulic pressure p within a wide range
from a low pressure to a high pressure. Further, the operation of
the cam ring 24 becomes stable so that a discharge pressure P also
becomes stable.
[0061] To be more specific, the cylinder 80 of the control valve 7
has the supply port 803 as a first port communicating with the
discharge opening 203, the communication port 804 as a second port
communicating with the second control chamber 292, and the drainage
port 805 as a third port communicating with the oil pan 400. These
ports 803 to 805 are open on the inner periphery of the cylinder
80. The various ports of the control valve 7 can be formed with a
simple configuration described above. It is sufficient for the
drainage port 805 to communicate with the low pressure portion. It
is not limited to the configuration that the drainage port 805
communicates with the oil pan 400 (atmospheric pressure). For
example, the drainage port 805 may communicate with the intake
opening 201 side (where an intake negative pressure is generated).
The spool 81 of the control valve 7 is movable in the cylinder 80.
The spool 81 includes: the first land portion 811 as a first large
diameter portion which can vary the area of the above-mentioned
opening of the supply port 803; and the second land portion 812 as
a second large diameter portion which can vary the area of the
above-mentioned opening of the drainage port 805. With such a
simple configuration of a spool valve, the valve portion 8 can
control a control hydraulic pressure p.
[0062] To be more specific, the first land portion 811 and the
second land portion 812 are disposed such that the respective ports
803 to 805 can be at least partially open simultaneously on the
inner periphery of the spool 81 within a range (space 807) between
the first land portion 811 and the second land portion 812.
Accordingly, simultaneous with the communication between the supply
port 803 (discharge opening 203) and the communication port 804
(second control chamber 292) via the space 807, the communication
port 804 (second control chamber 292) and the drainage port 805
(oil pan 400) can be made to communicate with each other. Further,
with the movement of the spool 81, the opening area Sd of the
drainage port 805 which is open to the space 807 (the
cross-sectional area of the flow passage through which working oil
in the second control chamber 292 is drained to the oil pan 400)
can be varied while the supply port 803 (discharge opening 203) and
the communication port 804 (second control chamber 292) are made to
communicate with each other. In other words, in a state where a
flow of working oil from the supply port 803 to the communication
port 804, and a flow of working oil from the communication port 804
to the drainage port 805 are allowed, the first land portion 811
can vary the cross-sectional area of the flow passage between the
supply port 803 and the communication port 804. Further, the second
land portion 812 can vary the cross-sectional area of the flow
passage between the communication port 804 and the drainage port
805. To be more specific, the first land portion 811 can vary the
area of the above-mentioned opening of the supply port 803. The
second land portion 812 can vary the area of the above-mentioned
opening of the drainage port 805. When the first land portion 811
varies the area of the above-mentioned opening of the supply port
803, the second land portion 812 varies the area of the
above-mentioned opening of the drainage port 805. With the movement
of the spool 81 to one side in the axial direction, the opening
area Sd decreases while the opening area Si of the supply port 803
which is open to the space 807 (the cross-sectional area of the
flow passage through which working oil is introduced from the
discharge opening 203 to the second control chamber 292) increases.
With the movement of the spool 81 to the other side in the axial
direction, the opening area Sd increases while the opening area Si
decreases.
[0063] The spool 81 includes the first land portion 811, the second
land portion 812, and the connecting portion 813. The connecting
portion 813 connects the first land portion 811 and the second land
portion 812 with each other. The first land portion 811 is disposed
on the supply port 803 side, and is biased to one side in the axial
direction by the solenoid portion 9. The second land portion 812 is
disposed on the drainage port 805 side, and is biased to the other
side in the axial direction by the spring 82. As described above,
the spring 82 and the solenoid portion 9 differ from each other in
the direction that the member biases the spool 81 and hence, the
electromagnetic force fm and the spring force fs act in opposite
directions. Accordingly, the solenoid portion 9 can favorably
control the spool 81. Further, the spring 82 functions as a return
spring for the spool 81 (the plunger of the solenoid portion 9).
Also in the case where there is a malfunction in the solenoid
portion 9, the spool 81 is biased to the other side in the axial
direction (toward the initial position) by the spring 82 so that it
is possible to set the amount of eccentricity .DELTA. to the
maximum. Therefore, it is possible to cause a discharge pressure P
to rise with the maximum gradient according to an increase in the
engine speed Ne.
[0064] The area of the first region 246 of the outer peripheral
surface 245 of the cam ring which faces the first control chamber
291 may be set equal to the area of the second region 246 of the
outer peripheral surface 245 of the cam ring which faces the second
control chamber 292. Alternatively, the area of the second region
247 may be set smaller than the area of the first region 246. In
this embodiment, the area of the second region 247 (pressure
receiving area) is larger than the area of the first region 246
(pressure receiving area). Accordingly, during the operation of the
pump 2 at a high speed, a stable hydraulic pressure P can be
supplied. That is, when an engine speed Ne (pump rotational speed)
rises, air bubbles may be generated in working oil. When these air
bubbles are collapsed in the working chamber 28 within the
discharge region, there is a possibility that a balance of pressure
which acts on the cam ring 24 is disturbed so that the behavior of
the cam ring 24 becomes unstable, thus causing discharge pressure P
to drop. However, even when the pressure in the first control
chamber 291 and the pressure in the second control chamber 292 are
equal to each other, hydraulic pressure force Fp2 is larger than
hydraulic pressure force Fp1. Accordingly, even if a balance of a
pressure which acts on the cam ring 24 from the working chamber 28
is disturbed, the cam ring 24 is biased in the direction that an
amount of eccentricity .DELTA. increases, thus suppressing that the
behavior of the cam ring 24 becomes unstable. Therefore, it is
possible to suppress dropping of control hydraulic pressure P so
that a stable control hydraulic pressure P can be supplied. In
other words, it becomes possible to discharge working oil of high
pressure.
[0065] The volume of the first control chamber 291 increases with
the movement of the cam ring 24 in the direction opposing the
biasing force Fs of the spring 25. That is, hydraulic pressure
force Fp1 acts in the direction opposite to the direction of
biasing force Fs. The volume of the second control chamber 292
increases with the movement of the cam ring 24 in the same
direction as biasing force Fs. That is, hydraulic pressure force
Fp2 acts in the same direction as biasing force Fs, thus assisting
the biasing force Fs. The operation of the cam ring 24 is decided
by the magnitude relationship between hydraulic pressure force Fp1
and the sum of hydraulic pressure force Fp2 and biasing force Fs
(Fp2+Fs). Accordingly, only a small biasing force Fs is required
for causing the cam ring 24 to be operated in the direction that
the amount of eccentricity .DELTA. increases. The load of the
spring 25 can be reduced. Accordingly, only a small hydraulic
pressure force Fp1 is required for causing the cam ring 24 to be
operated in the direction that the amount of eccentricity .DELTA.
decreases. That is, it is possible to lower a discharge pressure
when the cam ring 24 is operated in the direction that the amount
of eccentricity .DELTA. decreases. In other words, discharge of a
low pressure working oil can be realized. The cam ring 24 can be
oscillated about a fulcrum disposed in the pump accommodating
chamber 200. Accordingly, a range where the cam ring 24 is operated
can be made compact, thus realizing the reduction in size of the
pump 2.
[0066] Lowering a pressure in the second control chamber 292
increases the difference between the pressure in the second control
chamber 292 and the pressure at the discharge port 204.
Accordingly, there is a possibility of increase in the amount of
working oil to be leaked through a gap formed between the side
surface of the cam ring 24 in the axial direction and the bottom
surface of the pump accommodating chamber 200. However, the width
in the radial direction of the second region 247 of the cam ring 24
is larger than the width in the radial direction of the first
region 246. Accordingly, sealing property is improved more on the
second control chamber 292 side than on the first control chamber
291 side and hence, the above-mentioned leakage can be suppressed.
A discharge pressure is always introduced into the first control
chamber 291 so that the difference between the pressure in the
first control chamber 291 and the pressure at the discharge port
204 is small. Accordingly, sealing property is improved (the width
in the radial direction is increased) only on the second control
chamber 292 side and hence, unnecessary increase in weight is
suppressed.
Second Embodiment
[0067] First, the configuration is described. As shown in FIG. 13,
a cylinder 80C has a bottom portion 802 on one side in the axial
direction, and the other side of the cylinder 80C in the axial
direction is open. The opening of a communication port 804C is
formed on an inner peripheral surface 800 of the cylinder between
the opening of a supply port 803 and the opening of a drainage port
805. In the axial direction of the cylinder 80C, the size of the
above-mentioned opening of the communication port 804C is larger
than the sizes of the above-mentioned openings of the supply port
803 and the drainage port 805. A spool 81C includes a first land
portion 814, a second land portion 814, and the connecting portion
813. The size of the first land portion 814 in the axial direction
is smaller than the size of the above-mentioned opening of the
communication port 804C. The first land portion 814 is disposed in
a region which overlaps with the communication port 804C in the
axial direction of the cylinder 80C, and in the vicinity of such a
region. The drainage port 805 is always open to a space 807C, and
the communication port 804C may be open to the space 807C. The
supply port 803 is always open to a space 808C, and the
communication port 804C is open to the space 808C in the initial
state.
[0068] One end side of a spring 82C is fitted on the outer
peripheral side of a projection portion which projects from the
first land portion 814 of the spool 81C, and one end of the spring
82C is in contact with the end surface of the first land portion
814 on one side. The other end of the spring 82C is in contact with
a bottom portion 802. A spring force fs of the spring 82C biases
the first land portion 814 (spool 81C) to the other side in the
axial direction. A solenoid portion 9 is joined to the other side
of a valve portion 8 in the axial direction, thus closing the
opening of the cylinder 80C on the other side in the axial
direction. The second land portion 815 of the spool 81C is
integrally joined to a plunger. The electromagnetic force fin of
the solenoid portion 9 biases the second land portion 815 (the
spool 81C and the first land portion 814) to one side in the axial
direction. Other configurations are to the same as those in the
first embodiment and hence, corresponding constitutional elements
are given the same reference numerals, and the repeated description
of such constitutional elements is omitted.
[0069] Next, the manner of operation is described. The first land
portion 814 can vary the opening area of the communication port
804C. When the edge of the first land portion 814 on one side in
the axial direction is positioned on the other side in the axial
direction of the edge of the communication port 804C on one side in
the axial direction, the communication port 804C is at least
partially open to the space 808C. The above-mentioned opening of
the supply port 803 communicates with the above-mentioned opening
of the communication port 804C via the space 808C. The space 808C
forms a passage for working oil. When the edge of the first land
portion 814 on the other side in the axial direction is positioned
on one side in the axial direction of the edge of the communication
port 804C on the other side in the axial direction, the
communication port 804C is at least partially open to the space
807C. The above-mentioned opening of the drainage port 805
communicates with the above-mentioned opening of the communication
port 804C via the space 807C. The space 807C forms a passage for
working oil. When the first land portion 814 falls within a range
of the communication port 804C in the axial direction, the
communication port 804C is open to both sides of the first land
portion 814 in the axial direction so that the communication port
804C is partially open to both of the space 807C and the space
808C. The first land portion 814 moves within a range of the
communication port 804C in the axial direction, thus varying the
area Si of the above-mentioned opening of the communication port
804C, communicating with the above-mentioned opening of the supply
port 803, and the area Sd of the above-mentioned opening of the
communication port 804C, communicating with the above-mentioned
opening of the drainage port 805.
[0070] As shown in FIG. 14, when the spool 81C is at the initial
position, the first land portion 814 closes the opening of the
communication port 804C which is open to the space 807C and, the
first land portion 814 causes the communication port 804C to be
open to the space 808C, and sets the opening area Si of the
communication port 804C to the maximum Smax. A first state similar
to a state shown in FIG. 4 is realized so that the maximum amount
of eccentricity .DELTA. is maintained. As shown in FIG. 15, when
the spool 81C slightly moves to one side in the axial direction
from the initial position, the first land portion 814 causes the
communication port 804C to become open to the space 808C and,
causes the communication port 804C to become open to the space
807C. A second state similar to a state shown in FIG. 5 is
realized. The opening area Si becomes smaller than the maximum
value Smax. Working oil may be drained from the communication
passage 434 (second control chamber 292) via the space 807C.
Working oil may also be drained from the communication port 804C
via the space 807C, thus generating a flow of working oil toward
the space 807C from a supply passage 433 (space 808C) through the
communication port 804C. In this flow, the communication port 804C
with the decreased opening area Si functions as an orifice so that
a hydraulic pressure in the communication passage 434
(communication port 804C) becomes lower than a hydraulic pressure P
in the supply passage 43 (space 808C). Accordingly, a control
hydraulic pressure p introduced into the second control chamber 292
drops so that the amount of eccentricity .DELTA. decreases. As
shown in FIG. 16, when the spool 81C moves from the initial
position to one side in the axial direction by a distance larger
than a distance for the second state (FIG. 15), the first land
portion 814 increases the opening area Sd of the communication port
804C, which is open to the space 807C, and the first land portion
814 decreases the opening area Si of the communication port 804C,
which is open to the space 808C. A third state similar to a state
shown in FIG. 6 is realized. An increase in the opening area Sd
increases the amount of working oil drained from the space 807C
through the drainage passage 435. Accordingly, the amount of
working oil which may be drained from the communication passage 434
(second control chamber 292) via the space 807C increases. Further,
a decrease in the opening area Si decreases the orifice diameter of
the communication port 804C so that a hydraulic pressure in the
communication passage 434 becomes further lower than a hydraulic
pressure P in the supply passage 433. Accordingly, a control
hydraulic pressure p further drops so that the amount of
eccentricity .DELTA. further decreases.
[0071] In FIG. 14 to FIG. 16, a spring force fs acts on the spool
81C in the rightward direction, and an electromagnetic force fm
acts on the spool 81C in the leftward direction. When an
electromagnetic force fin becomes larger than a spring force fs,
the spool 81C moves to one side in the axial direction, thus
realizing a state transition from the first state toward the third
state. When an electromagnetic force fm becomes smaller than a
spring force fs, the spool 81C moves to the other side in the axial
direction, thus realizing a state transition from the third state
toward the first state.
[0072] Varying the cross-sectional area Sd of the flow passage
allows the drainage amount of working oil from the communication
port 804C (second control chamber 292) to be varied (adjusted).
With such variation, a control hydraulic pressure p is varied
(controlled). In this embodiment, simultaneous with the variation
in the cross-sectional area Sd, the discharge opening 203 and the
communication port 804C (second control chamber 292) are made to
communicate with each other. Accordingly, the drainage amount of
working oil from the second control chamber 292 varies slowly with
respect to the movement of the spool 81C. With the movement of the
spool 81C to one side in the axial direction, the control valve 7
increases the cross-sectional area Sd of the flow passage, through
which working oil in the second control chamber 292 is drained to
the oil pan 400, while decreasing the cross-sectional area Si of
the flow passage, through which working oil is introduced from the
discharge opening 203 to the second control chamber 292. With the
movement of the spool 81C to the other side in the axial direction,
the cross-sectional area Sd of the flow passage is decreased while
the cross-sectional area Si of the flow passage is increased.
[0073] To be more specific, the opening of the communication port
804C (second port) is formed on the inner peripheral surface 800 of
the cylinder between the opening of the supply port 803 (first
port) and the opening of the drainage port 805 (third port). The
spool 81C includes the first land portion 814 which is biased to
one side by the solenoid portion 9 and, is biased to the other side
by the spring 82C. The first land portion 814 varies the area Si of
the above-mentioned opening of the communication port 804C
communicating with the above-mentioned opening of the supply port
803, and the area Sd of the above-mentioned opening of the
communication port 804C communicating with the above-mentioned
opening of the drainage port 805. Accordingly, with such a simpler
configuration of a spool valve, the valve portion 8 can control a
control hydraulic pressure p. The manner of other operations and
advantageous effects are the same as those in the first embodiment.
The configuration of this embodiment is also applicable to any
embodiment other than the first embodiment.
Third Embodiment
[0074] First, the configuration is described. As shown in FIG. 17,
a pump 2 is configured such that, a cam ring 24A of the pump 2
moves in a slidable manner. The pump 2 does not include the first
sealing member 261, the second sealing member 262, and the pin 27
in the first embodiment. The inner peripheral surface of a pump
accommodating chamber 200A of a housing body 20A has planar
surfaces 205 to 207. These planar surfaces 205 to 207 expand
parallel to an axis 22AP of a rotor 22A. The planar surfaces 205,
206 are parallel to each other, and the planar surface 207 expands
in a direction orthogonal to these planar surfaces 205, 206. The
outer periphery of the cam ring 24A has four protrusions 246 to 249
which protrude outward in the radial direction. The first
protrusion 246 and the second protrusion 247 are disposed on sides
opposite to each other with respect to an axis 24AP of an inner
peripheral surface 240A of the cam ring, and the third protrusion
248 and the fourth protrusion 249 are disposed on sides opposite to
each other with respect to the axis 24AP. The first protrusion 247,
the second protrusion 247, and the third protrusion 248 have planar
surfaces, and these planar surfaces expand parallel to the axis
24AP. The planar surface of the first protrusion 246 and the planar
surface of the second protrusion 247 are parallel to each other. A
distance between both planar surfaces is slightly shorter than a
distance between the planar surfaces 205, 206 of the housing body
20A. The planar surface of the first protrusion 246 and the planar
surface of the second protrusion 247 respectively oppose the planar
surfaces 205, 206. The planar surface of the third protrusion 248
expands in a direction orthogonal to the planar surface of the
first protrusion 247 (second protrusion 247), and opposes the
planar surface 207 of the inner peripheral surface of the pump
accommodating chamber 200A. One end of a spring 25A is mounted on
the fourth protrusion 249.
[0075] A first control chamber 291A is formed of a space defined
between a portion of an outer peripheral surface 245A of the cam
ring ranging from the first protrusion 246 to the second protrusion
247 via the third protrusion 248 and the inner peripheral surface
of the pump accommodating chamber 200A. A second control chamber
292A is formed of a space defined between a portion of the outer
peripheral surface 245A of the cam ring ranging from the first
protrusion 246 to the second protrusion 247 via the fourth
protrusion 249 and the inner peripheral surface of the pump
accommodating chamber 200A. A spring accommodating chamber 293A is
integrally formed with the second control chamber 292A, and has a
bottomed cylindrical shape. The other end side of the spring 25A is
disposed in the spring accommodating chamber 293A. A gap formed
between the planar surface of the first protrusion 246 and the
planar surface 205 of the pump accommodating chamber 200A, and a
gap formed between the planar surface of the second protrusion 247
and the planar surface 206 of the pump accommodating chamber 200A
are small and hence, sealing is provided between the first control
chamber 291A and the second control chamber 292A (spring
accommodating chamber 293A).
[0076] The control valve 7 is configured such that, as shown in
FIG. 18, the valve portion 8 includes a retainer 83, and a stopper
84. The solenoid portion 9 includes a rod 91. The rod 91 is joined
to a plunger. The inner peripheral surface 800 of a cylinder 80A
has a cylindrical shape, and both ends of the cylinder 80A in the
axial direction are open. The retainer 83 has a bottomed
cylindrical shape, and has a hole 830 in a bottom portion 831. The
retainer 83 is disposed at the end of the cylinder 80A on the other
side in the axial direction. A cylindrical portion 832 of the
retainer 83 is fitted in the inner periphery of the cylinder 80A.
The stopper 84 has an annular shape, and has a hole 840 at a center
portion thereof. The stopper 84 is disposed at the end of the
cylinder 80A on the other side in the axial direction, and
partially closes the opening of the cylinder 80A. The surface of
the stopper 84 on one side in the axial direction opposes the
bottom portion 831 of the retainer 83. One end of the rod 91
projects to the inner peripheral side of the cylinder 80A, and is
joined to the end of a spool 81A (first land portion 811A) on the
other side in the axial direction. The rod 91 functions as a member
for allowing the solenoid to bias the spool 81A in the axial
direction. The rod 91 is integrally formed with the spool 81A (is
not separate from the spool 81A). A space 808A is defined between a
second land portion 812A and the retainer 83 in the cylinder 80A.
One end side of a spring 82A is fitted in the inner peripheral side
of the retainer 83, and one end of the spring 82A is in contact
with the bottom portion 831 of the retainer 83. The other end of
the spring 82A is in contact with the end surface of the spool 81A
(second land portion 812A) on one side in the axial direction.
Other configurations are to the same as those in the first
embodiment and hence, corresponding constitutional elements are
given the same reference numerals, and the repeated description of
such constitutional elements is omitted.
[0077] Next, the manner of operation is described. The rotor 22A
rotates in the clockwise direction in FIG. 17. The cam ring 24A can
slidably move (linearly move in the radial direction of the rotor
22) along the planar surfaces 205, 206 in the pump accommodating
chamber 200A. The planar surfaces 205, 206 are disposed in the pump
accommodating chamber 200A, and function as guide portions (guides)
for the above-mentioned movement. With a translational motion of
the cam ring 24A, the difference (amount of eccentricity .DELTA.)
between the axis (center of rotation) 22AP of the rotor 22A and the
axis (center) 24AP of the inner peripheral surface 240A of the cam
ring varies. The volume of the first control chamber 291A and the
volume of the second control chamber 292A are variable with the
movement of the cam ring 24A. The position of the cam ring 24A
(amount of eccentricity .DELTA.) is determined by a force Fp1
caused by a pressure in the first control chamber 291A, a force Fp2
caused by a pressure in the second control chamber 292A, and a
biasing force Fs of the spring 25A. When a force Fp1 becomes larger
than the sum of force Fp2 and biasing force Fs (Fp2+Fs), the cam
ring 24A moves to the side where an amount of eccentricity .DELTA.
(capacity) reduces. When a force Fp1 becomes smaller than the sum
of force Fp2 and biasing force Fs (Fp2+Fs), the cam ring 24A moves
to the side where an amount of eccentricity .DELTA. (capacity)
increases. When an electromagnetic force fm is equal to or less
than a spring force fs, as shown in FIG. 19, in the same manner as
FIG. 4, the spool 81A is at the initial position, and a supply port
803A communicates with a communication port 804A. The amount of
eccentricity .DELTA. becomes the maximum due to working oil
(control hydraulic pressure pmax) introduced into a second control
chamber 292A. When an electromagnetic force fm is larger than a
spring force fs, in the same manner as FIG. 5 and FIG. 6, the spool
81 moves to the other side in the axial direction from the initial
position so that a drainage port 805A communicates with the
communication port 804A (as well as the supply port 803A). Working
oil is drained from the second control chamber 292A and hence, an
amount of eccentricity .DELTA. decreases. As described above, the
configuration is adopted where the amount of eccentricity .DELTA.
(capacity) varies with a translational motion of the cam ring 24A
and hence, configurations of the respective control chambers 291A,
292A can be simplified. The manner of other operations and
advantageous effects are to the same as those in the first
embodiment. The configuration of this embodiment is also applicable
to an embodiment other than the first embodiment.
Fourth Embodiment
[0078] First, the configuration is described. A pump 2 is
configured such that, as shown in FIG. 20, as viewed in the axial
direction of a cam ring 24B, a first protrusion 241B and a second
protrusion 242B are disposed on the same side with respect to a
straight line passing through the axis of a pin 27B and a center
24BP of an inner peripheral surface 240B of the cam ring. The first
protrusion 241B is disposed between the second protrusion 242B and
a third protrusion 243B (pin 27B). The first protrusion 241B and
the second protrusion 242B are disposed on the side opposite to a
fourth protrusion 244B with respect to the above-mentioned straight
line. A first control chamber 291B is formed of a space defined
between a portion of an outer peripheral surface 245B of the cam
ring ranging from the first protrusion 241B (first sealing member
261B) to the third protrusion 243B (pin 27B) and the inner
peripheral surface of a pump accommodating chamber 200B. (A portion
of) a discharge port 204B and a discharge opening 203B are open on
the bottom surface of the pump accommodating chamber 200B which
faces the first control chamber 291B. A second control chamber 292B
is formed of a space defined between a portion of the outer
peripheral surface 245B of the cam ring ranging from the first
protrusion 241B (first sealing member 261B) to the second
protrusion 242B (second sealing member 262B) and the inner
peripheral surface of the pump accommodating chamber 200B. A second
region 247B of the outer peripheral surface 245B of the cam ring
between the first sealing member 261B and the second sealing member
262B faces the second control chamber 292. The second control
chamber 292B is sealed by the first sealing member 261B and the
second sealing member 262B. The other end of a communication
passage 434 is open on the bottom surface of the pump accommodating
chamber 200B which faces the second control chamber 292B. A spring
accommodating chamber 293B is formed of a space defined between a
portion of the outer peripheral surface 245B of the cam ring
ranging from the third protrusion 243B (pin 27B) to the second
protrusion 242B (second sealing member 262B) via the fourth
protrusion 244B and the inner peripheral surface of the pump
accommodating chamber 200B. (A portion of) an intake port 202B and
an intake opening 201B are open on the bottom surface of the pump
accommodating chamber 200B which faces the spring accommodating
chamber 293B. The discharge port 204B communicates with both of a
working chamber 28B and the first control chamber 291B, thus
functioning as a first feedback passage 431.
[0079] The control valve 7 is configured such that, as shown in
FIG. 21, the end portion of a cylinder 80B on one side in the axial
direction is not open, but is closed. One end of the spring 82 is
in contact with the above-mentioned end portion of the cylinder
80B. The cylinder 80B has a second drainage port 806 which
penetrates the cylinder 80B in a radial direction. A drainage port
805B, a communication port 804B, a supply port 803B, and the second
drainage port 806 are arranged in this order from one side to the
other side in the axial direction of the cylinder 80B. The drainage
port 805B is open to a space 807B in an initial state. The
communication port 804B is always open to the space 807B, and the
supply port 803B may be open to the space 807B. In the inside of
the cylinder 80B, a space 808 is defined between a second land
portion 812B and the end portion of the cylinder 80B on other side
in the axial direction. The supply port 803B is open to the space
808 in an initial state, and the second drainage port 806 is always
open to the space 808. The second drainage port 806 communicates
with an oil pan 400 through a drainage passage 435. Other
configurations are to the same as those in the first embodiment and
hence, corresponding constitutional elements are given the same
reference numerals, and the repeated description of such
constitutional elements is omitted.
[0080] Next, the manner of operation is described. A rotor 22B
rotates in the clockwise direction in FIG. 20. The cam ring 24B is
biased by a spring force Fs of a spring 25 to one side in the
rotational direction about the pin 27B (to the side where the
amount of increase or decrease in volume of each of the plurality
of working chambers 28B increases, and the amount of eccentricity
.DELTA. increases). The cam ring 24B is biased to the other side in
the rotational direction about the pin 27B (to the side where the
amount of increase or decrease in volume of each of the plurality
of working chambers 28B decreases, and the amount of eccentricity
.DELTA. decreases) by a force Fp1 which is received by a first
region 246B of the outer peripheral surface 245B, and which is
caused by a hydraulic pressure P in the first control chamber 291B,
and by a force Fp2 which is received by the second region 247B, and
which is caused by a hydraulic pressure P in the second control
chamber 292B. The volume of the first control chamber 291B and the
volume of the second control chamber 292B increase with the
movement of the cam ring 24B to the other side in the
above-mentioned rotational direction (in the direction opposite to
the direction of a spring force Fs). When the sum of force Fp1 and
force Fp2 (Fp1+Fp2) becomes larger than a spring force Fs, the cam
ring 24B oscillates to the other side in the above-mentioned
rotational direction and hence, an amount of eccentricity .DELTA.
(capacity) reduces. When the sum of force Fp1 and force Fp2
(Fp1+Fp2) becomes smaller than a spring force Fs, the cam ring 24B
oscillates to one side in the rotational direction about the pin
27B (to the side where the amount of eccentricity .DELTA.
increases) and hence, capacity increases.
[0081] A first land portion 811B of a spool 81B varies the opening
area of the drainage port 805B, and a second land portion 812B
varies the opening area of the supply port 803B. When an
electromagnetic force fm is equal to or less than a spring force fs
(set load of a spring 82B), as shown in FIG. 22, the spool 81B is
at the initial position and, in a state where the second land
portion 812 closes the opening of the supply port 803B which is
open to a space 807B, the first land portion 811B causes the
drainage port 805B to become open to the space 807B. The drainage
port 805B communicates with the communication port 804B. Working
oil is drained from a second control chamber 292B so that a force
Fp2 decreases. When the sum of force Fp1 and force Fp2 (Fp1+Fp2) is
smaller than a biasing force Fs (set load of the spring 25), an
amount of eccentricity .DELTA. becomes the maximum. Working oil is
drained from the space 808 through the second drainage port 806 and
hence, the space 808 is maintained at a low pressure. When an
electromagnetic force fm becomes larger than a spring force fs, the
spool 81B moves to the other side in the axial direction from the
initial position. In a state where the first land portion 811B
partially closes the opening of the drainage port 805B which is
open to the space 807B, the second land portion 812B causes the
supply port 803B to be partially open to the space 807B. The supply
port 803B communicates with the communication port 804B. The
communication passage 434 and the supply passage 433 are connected
with each other so that working oil discharged from a discharge
opening 203B is introduced into the second control chamber 292B. A
force Fp2 increases due to a hydraulic pressure p introduced into
the second control chamber 292B. When the sum of force Fp1 and
force Fp2 (Fp1+Fp2) becomes larger than a biasing force Fs, an
amount of eccentricity .DELTA. decreases.
[0082] As described above, the present invention is applicable to
the pump 2 having the configuration where the volumes of the first
control chamber 291B and the second control chamber 292B increase
(a pressure in the second control chamber 292B acts in a direction
that an amount of eccentricity .DELTA. is reduced) with the
movement of the cam ring 24B in the direction opposing the biasing
force Fs of a spring 25B. The characteristic of main gallery
hydraulic pressure P with respect to engine speed Ne can be easily
caused to approximate the desired characteristic. Additionally,
ease of control can be improved. The manner of other operations and
advantageous effects are to the same as those in the first
embodiment. The configuration of this embodiment is also applicable
to an embodiment other than the first embodiment.
Fifth Embodiment
[0083] First, the configuration is described. The basic
configuration of a pump 2 is to the same as that of the first
embodiment (FIG. 2). However, the pump 2 has only the first control
chamber 291, and does not have the second control chamber 292. To
be more specific, the pump 2 does not include the second protrusion
242 and the second sealing member 262. The basic configuration of a
control valve 7 is to the same as that in the fourth embodiment
(FIG. 21). The basic configuration of a control passage 43 is that
the same as in the first embodiment (FIG. 1). However, the control
passage 43 includes only the first feedback passage 431 which is
branched from the discharge passage 41, and does not include the
second feedback passage 432. The first feedback passage 431
includes a supply passage 433, a communication passage 434, and a
drainage passage 435. One end side of the supply passage 433 is
branched from the discharge passage 41, and the other end of the
supply passage 433 is connected to the supply port 803 B of the
control valve 7. One end of the communication passage 434 is
connected to the communication port 804 B of the control valve 7,
and the other end of the communication passage 434 is connected to
the first control chamber 291. One end of the drainage passage 435
is connected to the drainage port 805 of the control valve 7, and
the other end of the drainage passage 435 is connected to an oil
pan 400. The cam ring 24 receives a pressure p of working oil in
the first control chamber 291 (control hydraulic pressure p). A
first region 246 of the outer peripheral surface 245 of the cam
ring functions as a pressure receiving surface which receives a
control hydraulic pressure p. Other configurations are to the same
as those in the first embodiment and hence, corresponding
constitutional elements are given the same reference numerals, and
the repeated description of such constitutional elements is
omitted.
[0084] Next, the manner of operation is described. A cam ring 24 is
biased by a spring force Fs of a spring 25 to one side in the
rotational direction about a pin 27 (to the side where the amount
of increase or decrease in volume of each of the plurality of
working chambers 28 increases, and the amount of eccentricity
.DELTA. increases). The cam ring 24 is biased to the other side in
the rotational direction about the pin 27 (to the side where the
amount of increase or decrease in volume of each of the plurality
of working chambers 28 decreases, and the amount of eccentricity
.DELTA. decreases) by a force Fp1 which is caused by a control
hydraulic pressure P. When a force Fp1 becomes larger than a spring
force Fs, the cam ring 24 oscillates to the other side in the
above-mentioned rotational direction and hence, the amount of
eccentricity .DELTA. (capacity) reduces. When a force Fp1 becomes
smaller than a spring force Fs, the cam ring 24 oscillates to one
side in the rotational direction about the pin 27 (to the side
where the amount of eccentricity .DELTA. increases) and hence,
capacity increases. When an electromagnetic force fm is smaller
than a spring force fs, the spool 81 moves to one side in the axial
direction toward the initial position so that an amount of working
oil drained from the first control chamber 291 increases whereby a
force Fp1 decreases. When a force Fp1 is smaller than a spring
force Fs, an amount of eccentricity .DELTA. increases. When an
electromagnetic force fm is larger than a spring force fs, the
spool 81 moves to the other side in the axial direction.
Accordingly, working oil is introduced into the first control
chamber 291 and, the amount of working oil drained from the first
control chamber 291 decreases so that a force Fp1 increases. When a
force Fp1 becomes larger than a spring force Fs, an amount of
eccentricity .DELTA. decreases.
[0085] As described above, the present invention is also applicable
to the pump 2 having the configuration where the control mechanism
3 (control valve 7) controls a pressure in the first control
chamber 291. The characteristic of main gallery hydraulic pressure
P with respect to engine speed Ne can be easily caused to
approximate the desired characteristic. Additionally, ease of
control can be improved. The manner of other operations and
advantageous effects are to the same as those in the first
embodiment. The configuration of this embodiment is also applicable
to an embodiment other than the first embodiment.
OTHER EMBODIMENTS
[0086] Embodiments for carrying out the present invention have been
described heretofore with reference to drawings. However, the
specific configuration of the present invention is not limited to
any of the above-mentioned embodiments. The present invention also
includes embodiments to which design change or the like is added
without departing from the gist of the invention. Within a range
where at least a portion of the above-mentioned problem can be
solved or a range where at least a portion of the above-mentioned
advantageous effects can be acquired, respective constitutional
elements described in the claims the specification may be
arbitrarily combined or omitted. For example, the pump may also be
used in a working oil supply system for a mechanical device other
than a working oil supply system for an automobile or an engine.
The specific configuration of the vane pump is not limited to the
embodiments, and may be suitably changed. It is sufficient that the
pump is a variable capacity pump, and members other than vanes may
be used as pump structures. A member other than a cam ring may be
used as a movable member which causes the amount of increase or
decrease in volume of each of the plurality of working chambers
during the rotation of pump structures to be varied. For example, a
pump may be formed of a trochoid gear pump. In this case, by
disposing an outer rotor, which is an external gear, so as to allow
eccentric movement, and by disposing a control chamber and a spring
on the outer peripheral side of the outer rotor, it is possible to
realize a variable capacity pump (the outer rotor corresponds to
the movable member).
[0087] Each of the arithmetic operation portion and the reception
portion of the ECU is realized by software in a microcomputer in
the embodiments. However, the arithmetic operation portion or the
reception portion of the ECU may be realized by an electronic
circuit. An arithmetic operation means not only an arithmetic
operation using a formula, but also general processing performed on
software. The reception portion may be an interface of a
microcomputer, or may be software in the microcomputer. A control
signal may be a signal relating to a current value, or a signal
relating to the thrust of a solenoid. A method for controlling an
electric current to be supplied to a solenoid is not limited to PWM
control. Current values which correspond to rotational speeds of an
engine may be set in advance by a map. Characteristic information
which causes a control signal of a solenoid to be varied according
to variation in engine speed may be realized by performing an
arithmetic operation instead of being realized by a map in a
microcomputer.
[0088] [Other Aspects which May be Understood Based on
Embodiments]
[0089] Other aspects which may be understood based on the
above-mentioned embodiment are described hereinafter.
[0090] (1) In one aspect, a variable capacity pump includes:
[0091] a housing including a pump accommodating chamber
therein;
[0092] a pump structure disposed in the pump accommodating chamber,
and configured to vary volumes of a plurality of working chambers
with rotation, the pump structure being configured to discharge
from a discharge portion working oil introduced from an intake
portion by being rotationally driven;
[0093] a movable member disposed in the pump accommodating chamber,
and accommodating the pump structure to define the plurality of
working chambers, the movable member being configured to cause an
amount of increase or decrease in volume of each of the plurality
of working chambers during rotation of the pump structure to be
varied by moving so that an amount of eccentricity of a center of
an inner periphery of the movable member from a center of rotation
of the pump structure varies;
[0094] a first biasing member disposed in the pump accommodating
chamber in a state where a set load is applied to the first biasing
member, and configured to bias the movable member in a direction
that the amount of increase or decrease in volume of each of the
plurality of working chambers increases;
[0095] a first control chamber which is disposed between the pump
accommodating chamber and the movable member, and into which the
working oil discharged from the discharge portion is introduced, a
volume of the first control chamber increasing with movement of the
movable member in a direction opposing a biasing force of the first
biasing member;
[0096] a second control chamber which is disposed between the pump
accommodating chamber and the movable member, and into which the
working oil discharged from the discharge portion is introduced
through a passage, a volume of the second control chamber being
variable with movement of the movable member; and
[0097] a control valve provided in the passage, and configured to
vary, with movement of a valve element, a cross-sectional area of a
flow passage, through which working oil in the second control
chamber is drained to a low pressure portion, while making the
discharge portion and the second control chamber communicate with
each other.
[0098] (2) In a more preferred aspect, in the above-mentioned
aspect,
[0099] with movement of the valve element in a first direction, the
control valve increases the cross-sectional area of the flow
passage, through which working oil in the second control chamber is
drained to the low pressure portion, while decreasing a
cross-sectional area of a flow passage, through which working oil
is introduced from the discharge portion to the second control
chamber.
[0100] (3) In another preferred aspect, in any one of the
above-mentioned aspects,
[0101] with movement of the valve element in a second direction,
the control valve decreases the cross-sectional area of the flow
passage, through which working oil in the second control chamber is
drained to the low pressure portion, while increasing a
cross-sectional area of a flow passage through which working oil is
introduced from the discharge portion to the second control
chamber.
[0102] (4) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0103] the control valve is configured to continuously change a
position of the valve element.
[0104] (5) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0105] the control valve is configured to stop the valve element at
any position.
[0106] (6) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0107] the control valve includes a solenoid portion configured to
generate an electromagnetic force for biasing the valve
element.
[0108] (7) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0109] the solenoid portion is configured to move the valve element
to any position according to a control signal.
[0110] (8) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0111] the valve element is integrally coupled to a plunger of the
solenoid portion.
[0112] (9) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0113] the control valve includes a hollow member which
accommodates the valve element, and which has a first port
communicating with the discharge portion, a second port
communicating with the second control chamber, and a third port
communicating with a low pressure portion, openings of the first
port, the second port, and the third port being formed on an inner
periphery of the hollow member.
[0114] (10) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0115] the control valve includes a solenoid portion configured to
generate an electromagnetic force for biasing the valve element,
and
[0116] the valve element includes
[0117] a first land portion disposed on a first port side, and
biased to one side by the solenoid portion,
[0118] a second land portion disposed on a third port side, and
biased to an opposite side by a second biasing member, and
[0119] a connecting portion connecting the first land portion and
the second land portion with each other.
[0120] (11) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0121] the second land portion varies an area of the opening of the
third port as the first land portion varies an area of the opening
of the first port.
[0122] (12) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0123] the control valve includes a solenoid portion configured to
generate an electromagnetic force for biasing the valve
element,
[0124] the opening of the second port is disposed between the
opening of the first port and the opening of the third port,
[0125] the valve element includes a land portion biased to one side
by the solenoid portion, and biased to the opposite side by a
second biasing member, and
[0126] the land portion varies an area of the opening of the second
port communicating with the opening of the first port, and an area
of the opening of the second port communicating with the opening of
the third port.
[0127] (13) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0128] a volume of the second control chamber increases with
movement of the movable member in the same direction as a direction
of a biasing force of the first biasing member.
[0129] (14) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0130] the movable member includes a first pressure receiving
surface facing the first control chamber, and a second pressure
receiving surface facing the second control chamber, and having a
pressure receiving area larger than a pressure receiving area of
the first pressure receiving surface.
[0131] (15) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0132] the movable member is configured to oscillate around a
fulcrum in the pump accommodating chamber.
[0133] (16) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0134] the movable member is configured to perform a translational
motion in the pump accommodating chamber.
[0135] (17) In still another preferred aspect, in any one of the
above-mentioned aspects,
[0136] a volume of the second control chamber increases with
movement of the movable member in a direction opposing the biasing
force of the first biasing member.
[0137] (18) Further, from another view point, in one aspect, a
variable capacity pump includes:
[0138] a housing including a pump accommodating chamber
therein;
[0139] a pump structure disposed in the pump accommodating chamber,
and configured to vary volumes of a plurality of working chambers
with rotation, the pump structure being configured to discharge
from a discharge portion working oil introduced from an intake
portion by being rotationally driven;
[0140] a movable member disposed in the pump accommodating chamber,
and accommodating the pump structure to define the plurality of
working chambers, the movable member being configured to cause an
amount of increase or decrease in volume of each of the plurality
of working chambers during rotation of the pump structure to be
varied by moving so that an amount of eccentricity of a center of
an inner periphery of the movable member from a center of rotation
of the pump structure varies;
[0141] a first control chamber which is disposed between the pump
accommodating chamber and the movable member, and into which the
working oil discharged from the discharge portion is introduced, a
volume of the first control chamber increasing with movement of the
movable member in one direction;
[0142] a second control chamber which is disposed between the pump
accommodating chamber and the movable member, and into which the
working oil discharged from the discharge portion is introduced
through a passage, a volume of the second control chamber being
variable with movement of the movable member;
[0143] a cylindrical member having a hollow shape, and including a
first port communicating with the discharge portion, a second port
communicating with the second control chamber, and a third port
communicating with a low pressure portion, openings of the first
port, the second port, and the third port being formed on an inner
periphery of the cylindrical member; and
[0144] a control valve including a spool movable in the cylindrical
member, and a solenoid portion configured to move the spool.
[0145] The spool includes a first large diameter portion configured
to vary an area of the opening of the first port, and a second
large diameter portion configured to vary an area of the opening of
the third port, and the first large diameter portion and the second
large diameter portion are disposed on the inner periphery of the
cylindrical member within a range sandwiched between the first
large diameter portion and the second large diameter portion such
that the first port, the second port, and the third port are
allowed to be at least partially open simultaneously.
[0146] (19) In one aspect, a working oil supply system for an
internal combustion engine includes:
[0147] a variable capacity pump which introduces working oil
discharged from a pump structure into a control chamber disposed
around a movable member, which accommodates the pump structure
therein, so as to move the movable member to vary an amount of
eccentricity of a center of the movable member from a center of
rotation of the pump structure, thus varying a pressure of working
oil discharged from the pump structure to the internal combustion
engine;
[0148] a pressure measuring portion configured to measure a
pressure of working oil discharged from the pump structure;
[0149] a rotational speed measuring portion configured to measure a
rotational speed of the internal combustion engine; and
[0150] a control portion which calculates a pressure difference
between a pressure measured by the pressure measuring portion and a
pressure of working oil which the internal combustion engine is
required to have at the rotational speed measured by the rotational
speed measuring portion, the control portion varying, when the
rotational speed is equal to or more than a predetermined
rotational speed and the pressure difference is larger than a
predetermined pressure difference, a drainage amount of working oil
from the control chamber to a low pressure portion while allowing
working oil to be introduced into the control chamber until the
pressure difference becomes equal to or less than the predetermined
pressure difference.
[0151] (20) In a more preferred aspect, in the above-mentioned
aspect,
[0152] the control portion does not drain working oil from the
control chamber to the low pressure portion when the rotational
speed is less than the predetermined rotational speed.
[0153] (21) In another preferred aspect, in any one of the
above-mentioned aspects,
[0154] the control portion controls, when the rotational speed is
equal to or more than the predetermined rotational speed and the
pressure difference is equal to or less than the set pressure
difference, a drainage amount of working oil from the control
chamber to the low pressure portion at a predetermined fixed amount
until the pressure difference becomes larger than the set pressure
difference.
[0155] This application claims priority to Japanese patent
application No. 2016-181736 filed on Sep. 16, 2016. The entire
disclosure, including the specification, the claims, the drawings,
and the abstract of Japanese patent application No. 2016-181736
filed on Sep. 16, 2016 is incorporated herein by reference.
REFERENCE SIGNS LIST
[0156] 1 working oil supply system [0157] 2 variable capacity pump
[0158] 20 housing body [0159] 200 pump accommodating chamber [0160]
201 intake opening (intake portion) [0161] 203 discharge opening
(discharge portion) [0162] 22 rotor (pump structure) [0163] 23 vane
(pump structure) [0164] 24 cam ring (movable member) [0165] 25
spring (first biasing member) [0166] 28 working chamber [0167] 291
first control chamber [0168] 292 second control chamber [0169] 3
control mechanism [0170] 4 passage [0171] 400 oil pan (low pressure
portion) [0172] 6 engine control unit (control portion) [0173] 7
control valve [0174] 8 valve portion [0175] 81 spool (valve body)
[0176] 9 solenoid portion
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