U.S. patent application number 15/227670 was filed with the patent office on 2017-02-09 for engine cooling device.
This patent application is currently assigned to AISIN SEIKI KABUSHIKI KAISHA. The applicant listed for this patent is AISIN SEIKI KABUSHIKI KAISHA, TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Yuta HIRATSUKA, Kenichi KOMURO, Ryusuke SASAKI, Noboru TAKAGI, Masazumi YOSHIDA.
Application Number | 20170037769 15/227670 |
Document ID | / |
Family ID | 56567474 |
Filed Date | 2017-02-09 |
United States Patent
Application |
20170037769 |
Kind Code |
A1 |
YOSHIDA; Masazumi ; et
al. |
February 9, 2017 |
ENGINE COOLING DEVICE
Abstract
An engine cooling device includes: a water pump; a radiator; a
first cooling water channel going through the radiator; a second
cooling water channel not going through the radiator; a solenoid
valve provided in the second cooling water channel; and a control
unit. The control unit moves, at a time of closing the solenoid
valve, a valve body in a valve closing direction while the cooling
water is passing at a decreased flow rate so as to close the
solenoid valve to cut off passage of the cooling water in the
second cooling water channel.
Inventors: |
YOSHIDA; Masazumi;
(Handa-shi, JP) ; HIRATSUKA; Yuta; (Kariya-shi,
JP) ; KOMURO; Kenichi; (Obu-shi, JP) ; SASAKI;
Ryusuke; (Kariya-shi, JP) ; TAKAGI; Noboru;
(Toyota-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AISIN SEIKI KABUSHIKI KAISHA
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Kariya-shi
Toyota-shi |
|
JP
JP |
|
|
Assignee: |
AISIN SEIKI KABUSHIKI
KAISHA
Kariya-shi
JP
TOYOTA JIDOSHA KABUSHIKI KAISHA
Toyota-shi
JP
|
Family ID: |
56567474 |
Appl. No.: |
15/227670 |
Filed: |
August 3, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01P 5/12 20130101; F01P
2005/125 20130101; F01P 7/165 20130101; F01P 2007/146 20130101;
F01P 7/16 20130101; F01P 3/20 20130101 |
International
Class: |
F01P 7/16 20060101
F01P007/16; F01P 5/12 20060101 F01P005/12; F01P 3/20 20060101
F01P003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2015 |
JP |
2015-153962 |
Claims
1. An engine cooling device comprising: a water pump that controls
a flow rate of cooling water for cooling an engine; a radiator; a
first cooling water channel that passes the cooling water to the
engine through the radiator; a second cooling water channel that
passes the cooling water to the engine without going through the
radiator; a solenoid valve provided in the second cooling water
channel, the solenoid valve including a valve body, the valve body
being moved by electric suction force to open and close the
solenoid valve; and a control unit configured to execute control,
at a time of closing the solenoid valve in the second cooling water
channel, to close the solenoid valve so as to cut off passage of
the cooling water in the second cooling water channel by moving the
valve body in a valve closing direction with at least electric
suction force while the cooling water is passing at a decreased
flow rate, the decreased flow rate being achieved by driving the
water pump so as to decrease the flow rate of the cooling
water.
2. The engine cooling device according to claim 1, wherein the
solenoid valve includes an urging member that urges the valve body
in the valve closing direction, the valve body being configured to
be moved in the valve closing direction with urging force of the
urging member and the electric suction force while the water pump
is driven.
3. The engine cooling device according to claim 1, wherein: the
control unit is configured to execute control to close the solenoid
valve in the second cooling water channel by acquiring a
valve-closable maximum speed of the water pump based on at least
flow resistance of the cooling water and by moving the valve body
while the water pump is driven at a speed equal to or less than the
valve-closable maximum speed.
4. The engine cooling device according to claim 3, further
comprising a thermostat provided in the first cooling water
channel, the thermostat having opening that changes based on
temperature of the cooling water, wherein the control unit is
configured to estimate the flow resistance of the cooling water
based on the opening of the thermostat.
5. The engine cooling device according to claim 1, wherein: the
water pump is an electrically-operated water pump including a
sensorless motor.
6. The engine cooling device according to claim 1, wherein: the
control unit is configured to execute control so as to increase the
flow rate of the cooling water with the water pump after closing of
the solenoid valve in the second cooling water channel is
completed.
Description
INCORPORATION BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2015-153962 filed on Aug. 4, 2015 including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an engine cooling
device.
[0004] 2. Description of Related Art
[0005] An engine cooling device including a water pump and a
solenoid valve is known (see, for example, Japanese Patent
Application Publication No. 2013-108398).
[0006] The engine cooling system disclosed in JP 2013-108398 A
includes: an electrically-operated pump that discharges coolant for
cooling an engine; a first channel and a second channel that pass
cooling water to the engine through a radiator; a third channel
that passes the cooling water to the engine without going through
the radiator; a valve provided in the third channel to switch
presence and absence of passage of the coolant in the third
channel; and a control unit that controls the electrically-operated
pump and the valve. The valve of the engine cooling system includes
a valve body, a valve seat, an urging member that urges the valve
body toward the valve seat side, and a solenoid that provides close
contact between the valve seat and the valve body upon
energization. Accordingly, the control unit is configured to
energize the solenoid at the time of closing the valve in the third
channel, so that the valve body and the valve seat are contacted
with urging force by the urging member and suction force by the
solenoid. The control unit is also configured to stop energization
of the solenoid at the time of opening the valve in a closed state,
while passing the coolant with the electrically-operated pump, so
that the valve body and the valve seat are separated against the
urging force of the urging member.
[0007] In the engine cooling system described in JP 2013-108398 A,
the control unit is configured to stop the electrically-operated
pump, at the time of closing the valve in the opened state in the
third channel, to stop passage of the coolant, and then energize
the solenoid of the valve in the third channel.
SUMMARY OF THE INVENTION
[0008] However, the engine cooling system disclosed in JP
2013-108398 A is configured to stop the electrically-operated pump
to thereby stop passage of the coolant in order to close the valve
in the third channel that passes the cooling water to the engine
without going through radiator. This causes an inconvenience that
the passage of the coolant is stopped in the engine cooling system
during the period when the electrically-operated pump is stopped.
Accordingly, since the engine is hardly cooled in the period when
the electrically-operated pump is stopped, the engine during
driving may become high in temperature.
[0009] The present invention provides an engine cooling device
capable of preventing the engine during driving from becoming high
in temperature when the solenoid valve in the cooling water channel
that passes cooling water to the engine without going through a
radiator is put in a closed state.
[0010] An engine cooling device according to an aspect of the
present invention includes: a water pump that controls a flow rate
of cooling water for cooling an engine; a radiator; a first cooling
water channel that passes the cooling water to the engine through
the radiator; a second cooling water channel that passes the
cooling water to the engine without going through the radiator; a
solenoid valve provided in the second cooling water channel, the
solenoid valve including a valve body, the valve body being moved
by electric suction force to open and close the solenoid valve; and
a control unit configured to execute control, at a time of closing
the solenoid valve in the second cooling water channel, to close
the solenoid valve so as to cut off passage of the cooling water in
the second cooling water channel by moving the valve body in a
valve closing direction with at least electric suction force while
the cooling water is passing at a decreased flow rate, the
decreased flow rate being achieved by driving the water pump so as
to decrease the flow rate of the cooling water.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Features, advantages, and technical and industrial
significance of exemplary embodiments of the invention will be
described below with reference to the accompanying drawings, in
which like numerals denote like elements, and wherein:
[0012] FIG. 1 is a schematic view illustrating an engine cooling
device and an engine according to one embodiment of the present
invention;
[0013] FIG. 2 illustrates an opening characteristics map according
to one embodiment of the present invention;
[0014] FIG. 3 illustrates a flow resistance map according to one
embodiment of the present invention;
[0015] FIG. 4 is a sectional view illustrating the structure of an
FSV of the engine cooling device according to one embodiment of the
present invention;
[0016] FIG. 5 illustrates a timing chart at the time of closing an
FSV according to one embodiment of the present invention;
[0017] FIG. 6 illustrates a timing chart at the time of closing the
FSV according to the related art;
[0018] FIG. 7 is a flowchart illustrating a control flow of closing
the FSV in the engine cooling device according to one embodiment of
the present invention;
[0019] FIG. 8 illustrates a cooling loss map according to one
embodiment of the present invention;
[0020] FIG. 9 illustrates a speed map according to one embodiment
of the present invention; and
[0021] FIG. 10 illustrates a closing time map according to one
embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENT
[0022] An embodiment of the present invention will be described
hereinbelow with reference to the drawings.
[0023] First, the configuration of an engine cooling device 100
according to one embodiment of the present invention will be
described with reference to FIGS. 1 to 4.
[0024] The engine cooling device 100 in one embodiment of the
present invention is mounted on a vehicle which is not illustrated.
The engine cooling device 100 supplies cooling water (coolant) to
an engine 101 mounted on the vehicle to cool the engine 101, cools
the cooling water warmed with heat of the engine 101 or the like by
using a radiator 2, and recovers heat from the warmed cooling water
using a heater core 3 or the like. The cooling water refers to
liquid such as water that is used to cool the engine 101.
[0025] As illustrated in FIG. 1, the engine cooling device 100
includes an electric water pump (electric WP) 1, a radiator 2, a
heater core 3, an oil cooler 4, a thermostat 5, and a flow shutting
valve (FSV) 6. The engine cooling device 100 is configured to be
controlled by an engine control unit (ECU) 7 that controls the
speed of the engine 101 and the like. The electric WP 1 is one
example of "a water pump" in the claims, and the FSV 6 is one
example of "a solenoid valve" in the claims. The ECU 7 is one
example of "a control unit" in the claims.
[0026] The engine cooling device 100 is configured so that cooling
water passes and circulates through a cooling water circulation
channel 8. The cooling water circulation channel 8 includes cooling
water channels 8a, 8b, and 8c. The cooling water channels 8a and 8b
are examples of "a first cooling water channel" and "a second
cooling water channel" in the claims, respectively.
[0027] In the cooling water channel 8a, the engine 101, the
electric WP 1, the radiator 2, and the thermostat 5 are arranged.
The electric WP 1 is arranged on the upstream side of the engine
101, the radiator 2 is arranged on the downstream side of the
engine 101, and the thermostat 5 is arranged on the downstream side
of the radiator 2. That is, the cooling water channel 8a is
configured to pass the cooling water to the engine 101 through the
radiator 2. Note that "upstream side" and "downstream side" in the
present embodiment refer to the upstream side and the downstream
side in a cooling water passage direction (chain double-dashed
lines in FIG. 1), respectively.
[0028] The cooling water channels 8b and 8c each branch at a branch
point 9a of the cooling water channel 8a that is on the downstream
side of the engine 101 and on the upstream side of the radiator 2,
and join at a junction 9b of the cooling water channel 8a that is
on the downstream side of the thermostat 5 and on the upstream side
of the electric WP 1. In short, the cooling water channel 8b and
the cooling water channel 8c are provided in parallel.
[0029] In the cooling water channel 8b, the heater core 3 and the
FSV 6 are arranged. More particularly, the cooling water channel
8b, which is the cooling water channel provided with the FSV 6, is
also configured to join the cooling water channel 8a at the
junction 9b without going through the radiator 2 so that the
cooling water can be passed to the engine 101. The heater core 3 is
arranged on the side of the branch point 9a, while the FSV 6 is
arranged on the side of the junction 9b.
[0030] In the cooling water channel 8c, the oil cooler 4 is also
arranged. More particularly, the cooling water channel 8c is
configured to join the cooling water channel 8a at the junction 9b
without going through the radiator 2 so that the cooling water can
be passed to the engine 101.
[0031] The electric WP 1, which is electrically operated, is
configured to control the flow rate of the cooling water discharged
under the control of the ECU 7. The electric WP 1 is configured to
suck the cooling water in the cooling water channel 8a on the side
opposite to the engine 101 and to discharge the cooling water
toward the engine 101. The electric WP 1 is a centrifugal pump
having excellent discharging efficiency.
[0032] The electric WP 1, which is a centrifugal pump, includes a
brushless sensorless motor 1a for rotating an impeller which is not
unillustrated. Accordingly, the electric WP 1 can be driven
independently of the engine 101. Note that "the brushless motor" is
a motor driven so that operation such as switching the direction of
an electric current is controlled by electric control without use
of brushes that contact-slides and commutators that switch the
direction of the electric current. Accordingly, in the case of
using the brushless sensorless motor 1a, which is free from wear of
the brushes unlike the case of using a motor with brushes, the life
of the electric WP 1 can be lengthened. The brushless sensorless
motor 1a does not include a sensor (Hall element or the like) that
detects the position of a rotor (permanent magnet). Accordingly,
the brushless sensorless motor 1a is configured to detect an
initial position of the rotor based on change in electromotive
force generated upon rotation of the rotor. The brushless
sensorless motor 1a is one example of "a sensorless motor" in the
claims.
[0033] The electric WP 1 is configured to be able to transmit speed
of the brushless sensorless motor 1a (speed of an impeller) to the
ECU 7 as pump speed information.
[0034] The radiator 2 is configured to perform heat exchange
between the cooling water passing inside the radiator 2 and the
running wind (air). Accordingly, the cooling water passing through
the radiator 2 is cooled.
[0035] The heater core 3 is configured to receive air sent from a
fan, which is not illustrated, based on a signal from the ECU 6
when heating operation is performed inside the vehicle which is not
illustrated. This leads to heat exchange between the cooling water
passing through the heater core 3 (cooling water channel 8b) and
wind (air), so that the cooling water is cooled and warm air is
supplied into the vehicle to heat the inside of the vehicle.
[0036] The oil cooler 4 exchanges heat between the cooling water
passing through the oil cooler 4 (cooling water channel 8c) and oil
used for such purposes as lubricating a sliding portion (not
illustrated) of the engine 101, so that the cooling water is warmed
and the oil is cooled.
[0037] The thermostat 5 is configured to have opening that changes
based on the temperature of cooling water. Accordingly, the
thermostat 5 has a function of switching between passing and not
passing the cooling water to the radiator 2 in the cooling water
channel 8a, and a function of regulating the flow rate of the
cooling water when the cooling water is passed to the radiator
2.
[0038] Specifically, the thermostat 5 is configured to be fully
closed (having an opening of 0%), as illustrated in FIG. 2, to
prevent the cooling water from passing to the radiator 2 in the
cooling water channel 8a when the temperature of the cooling water
passing through the thermostat 5 is less than a first temperature
(=about 80.degree. C.). In this case, the cooling water passes from
the branch point 9a to the cooling water channel 8b (with the FSV
in the opened state) and to the cooling water channel 8c, and then
passes (circulates) back to the electric WP 1 again from the
junction 9b, so that the cooling water is not cooled in the
radiator 2. The thermostat 5 is configured to regulate the flow
rate of the cooling water passing through the thermostat 5 based on
the opening that changes in accordance with the temperature of
cooling water when the temperature of the cooling water is equal to
or more than the first temperature. In this case, the cooling water
passes through the radiator 2 in the cooling water channel 8a at
the flow rate regulated in accordance with the opening of the
radiator 2, so that part of the cooling water is cooled in the
radiator 2, while the remaining cooling water passes through the
cooling water channel 8b (when the FSV is in the opened state) and
through the cooling water channel 8c, and then passes (circulates)
back to the electric WP 1 again from the junction 9b. The
thermostat 5 is configured to be fully opened (having an opening of
100%) when the temperature of the cooling water is equal to or more
than a second temperature. In this case, the cooling water passes
through the cooling water channel 8a, the cooling water channel 8b
(with the FSV in the opened state), and the cooling water channel
8c, and then passes (circulates) back to the electric WP 1 again,
so that part of the cooling water is cooled in the radiator 2.
[0039] As a result, in the engine cooling device 100, the channels
that pass the cooling water and the flow rate of each channel
change in accordance with the opened state of the thermostat 5.
Therefore, the engine cooling device 100 is configured so that
resistance (flow resistance) of cooling water passing through the
engine cooling device 100 (cooling water circulation channel 8)
changes in accordance with the opening of the thermostat 5. When
the opening of the thermostat 5 is small as illustrated in FIG. 3,
the flow resistance with respect to the flow rate of cooling water
becomes large, whereas when the opening of the thermostat 5 is
large, the flow resistance with respect to the flow rate of the
cooling water becomes small. Since the flow resistance changes
depending on structural factors of the engine cooling device 100,
such as a diameter of the cooling water circulation channel 8, the
flow resistance is calculated for each of the engine cooling
devices 100 having different structural factors.
[0040] The FSV 6, which is a valve member that is opened and closed
by electric suction force, has a function of cutting off passage of
cooling water in the cooling water channel 8b upon being closed. As
illustrated in FIG. 4, the FSV 6 includes a cylindrical housing 61,
and a valve body 62, a valve seat 63, an urging member 64 and a
solenoid 65 which are arranged inside the housing 61. The housing
61 has an inflow passage 61a that receives inflow of cooling water
coming from side of the heater core 3, an outflow passage 61b
extending in a direction substantially orthogonal to the direction
(Z direction) that the inflow passage 61a extends, the outflow
passage 61b making the cooling water flowing out to the side of the
electric WP 1, and a valve body housing portion 61c that provides
connection between the inflow passage 61a and the outflow passage
61b. The valve body housing portion 61c houses the valve body 62
and the urging member 64.
[0041] The solenoid 65, which is configured with an annular member,
has a body 65a made of a magnetic substance, a bobbin 65b arranged
inside the body 65a, and a winding wire 65c wound around the bobbin
65b to generate a magnetic field upon energization. The solenoid 65
is arranged inside the housing 61 so that an inner side of the
solenoid 65 forms the inflow passage 61a, and a surface of the
solenoid 65 on the side of the valve body housing portion 61c (Z1
side) serves as the valve seat 63 that comes into contact with the
valve body 62.
[0042] The valve body 62, which has a cross section formed into a
reversed T-shaped circular cylindrical form, is configured to be
movable in Z direction. The valve body 62 is formed of a magnetic
substance such as iron. Accordingly, when the solenoid 65 is
magnetized by energization of the winding wire 65c of the solenoid
65, electric suction force is generated between the valve body 62
and the solenoid 65 in a valve closing direction (Z2 direction) in
which the valve body 62 moves toward the valve seat 63. The urging
member 64, which is configured with a coiled spring, is arranged in
the valve body housing portion 61c while the valve body 62 is urged
in the valve closing direction.
[0043] As a result of these arrangements, the FSV 6 is configured
to be in the closed state when the urging force by the urging
member 64 and the electric suction force by the energized solenoid
65 move the valve body 62 in the valve closing direction (Z2
direction) and puts the valve body 62 in contact with the valve
seat 63. In the state where energization of the solenoid 65 is
canceled, the force applied to the valve body 62 from Z2 side based
on the pressure of the cooling water in the inflow passage 61a and
on the pressure of the cooling water in the outflow passage 61b and
in the valve body housing portion 61c may exceed the urging force.
In this case, the valve body 62 is moved in the valve opening
direction (Z1 direction), and the FSV 6 is switched from the closed
state to the opened state.
[0044] Here, both the urging force of the urging member 64 and the
suction force by the solenoid 65 are small. The area (area of a
region surrounded by a chain double-dashed line in the drawing of
the valve in the opened state in FIG. 4) S1 of the valve body 62
that receives pressure from Z2 side in the opened state is larger
than the area (area of a region surrounded by a chain double-dashed
line in the drawing of the valve in the closed state in FIG. 4) S2
of the valve body 62 that receives pressure from Z2 side in the
closed state. As a result, in a normal driving state where the
electric WP 1 is driven at the speed of discharging the cooling
water at a large flow rate, such as about 2000 rpm, the FSV 6 in
the opened state cannot resist the pressure of the cooling water
only with the urging force of the urging member 64 and the suction
force by the solenoid 65. Therefore, in the case of passing the
cooling water through the FSV 6 in the opened state at a normal
flow rate, it is difficult to switch the FSV from the opened state
to the closed state.
[0045] Accordingly, in the engine cooling device 100 of the present
embodiment, the ECU 7 is configured to, at the time of switching
the FSV 6 in the cooling water channel 8b from the opened state to
the closed state, energize the solenoid 65 while performing
low-speed driving of the electric WP 1 at a low speed of, for
example, about 700 rpm or less to make the flow rate of the cooling
water discharged from the electric WP 1 smaller than the normal
flow rate. Accordingly, in the engine cooling device 100, the valve
body 62 is moved in the valve closing direction with the urging
force of the urging member 64 and the electric suction force while
the electric WP 1 is driven, so that the FSV 6 in the cooling water
channel 8b is closed. As a result, passage of the cooling water in
the cooling water channel 8b is cut off. Meanwhile, even during
valve closing operation of the FSV 6 and after completion of the
valve closing operation, the cooling water passes through the
cooling water channels other than the cooling water channel 8b,
including the cooling water channel 8a when the thermostat 5 is
opened and the cooling water channel 8c. This makes it possible to
pass the cooling water to the engine 101. A detailed description of
the control executed by the ECU 7 to close the FSV 6 will be given
later.
[0046] The FSV 6 is closed to cut off the passage of the cooling
water to the heater core 3 in such cases as the case of preventing
the cooling water warmed with the engine 101 from passing to the
heater core 3 (cooling water channel 8b) to enhance cooling
efficiency inside the vehicle, and the case of cutting off the
passage of the cooling water to the heater core 3 and increasing
the flow rate of the cooling water passing through the side of the
oil cooler 4 (cooling water channel 8c) to enhance cooling
efficiency of the oil in the oil cooler 4. It is determined by the
ECU 7 whether or not the FSV 6 is closed to cut off passage of the
cooling water to the heater core 3.
[0047] As illustrated in FIG. 1, a water temperature sensor 7a is
arranged in the engine cooling device 100 to detect downstream
temperature (outlet temperature To) of the cooling water in the
cooling water channel 8a on the downstream side of the engine 101.
The water temperature sensor 7a is configured to transmit
information (outlet water temperature information) about the outlet
water temperature To to the ECU 7.
[0048] A description is now given of comparison between a timing
chart at the time of closing the FSV 6 in one embodiment of the
present invention and a timing chart at the time of closing an FSV
in the related art with reference to FIG. 1 and FIGS. 4 to 6.
[0049] First, the timing chart at the time of closing the FSV 6 in
the present embodiment illustrated in FIG. 5 will be described.
[0050] In the case of cutting off the passage of cooling water to
the heater core 3 (see FIG. 1) in the cooling water channel 8b
while the electric WP 1 is in a normal driving state, the ECU 7
first calculates a maximum speed of the electric WP 1 that can
close the FSV 6 (valve-closable maximum speed) in the present
embodiment. Then, the ECU 7 performs drive control of the electric
WP 1 to conduct low-speed driving of the electric WP 1 at the
calculated valve-closable maximum speed. As a consequence, the
electric WP 1 is put in a low-speed driving state, though the
passage (circulation) of cooling water in the engine cooling device
100 (the cooling water channel 8a going through the radiator 2
(when the thermostat 5 is opened) and the cooling water channel 8c)
is continued. The ECU 7 energizes the FSV 6 at substantially the
same time when instructing low-speed driving of the electric WP 1.
Consequently, electric suction force in the valve closing direction
(see FIG. 4) is applied to the valve body 62. Here, even when the
cooling water is passed through the FSV 6, the total force made up
of the suction force by the solenoid 65 and the urging force by the
urging member 64 is larger than the force based on the pressure of
the cooling water, because the electric WP 1 is driven at the
valve-closable maximum speed. Accordingly, the FSV 6 is closed.
[0051] After closing of the FSV 6 is completed, the ECU 7 performs
drive control to normally drive the electric WP 1. Consequently,
the speed of the electric WP 1 increases, which increases the flow
rate of the cooling water to be discharged.
[0052] A description is now given of the timing chart at the time
of closing the FSV in the related art illustrated in FIG. 6. An
engine cooling device in the related art has the configuration same
as that of the engine cooling device 100 in the embodiment, though
driving of an electric WP is stopped at the time of closing the
FSV.
[0053] Assume the case where passage of cooling water to the heater
core is desired to be cut off when the electric WP is in the normal
driving state. In this case, the ECU stops driving of the electric
WP in the related art. Then, after fluctuation in a front-rear
differential pressure of the FSV is settled down and the
differential pressure almost disappears, the ECU energizes the FSV.
As a consequence, the FSV is closed. The ECU performs drive control
of the electric WP to re-drive the electric WP at substantially the
same time when energizing the FSV. In this case, a start-up driving
period is needed until normal-driving of the electric WP is
actually performed after the ECU instructs driving of the electric
WP, because the electric WP includes a brushless sensorless
motor.
[0054] As a result, at the time of closing the FSV in the engine
cooling device in the related art, circulation of the cooling water
in the engine cooling device is stopped during a stop period of the
electric WP that is required to close the FSV and during a period
for start-up driving. This lengthens the period when the engine is
not cooled, as a result of which the engine becomes high in
temperature due to insufficient cooling of the engine during
driving. Contrary to this, in the engine cooling device 100 of the
present embodiment, low-speed driving of the electric WP 1
continues even while the FSV 6 is controlled to be closed.
Accordingly, the cooling water is passed into the engine cooling
device 100 (the cooling water channel 8a when the thermostat 5 is
opened and the cooling water channel 8c), so that the cooling water
is passed to the engine 101 during driving. Furthermore, unlike the
engine cooling device in the related art, the period for start-up
driving of the electric WP 1 is not generated. This makes it
possible to effectively prevent the inconvenience attributed to
insufficient cooling of the engine 101 from occurring.
[0055] A description is now given of the control flow of closing
the FSV 6 in one embodiment of the present invention with reference
to FIGS. 1 to 5 and FIGS. 7 to 10. The control flow is performed by
the ECU 7 (see FIG. 1).
[0056] First, as illustrated in FIG. 7, in step S1, it is
determined whether or not the FSV 6 in the cooling water channel 8b
needs to be closed, and the control operation in step S1 is
repeated until it is determined that the FSV 6 needs to be closed.
When it is determined that the FSV 6 needs to be closed, a
downstream temperature (outlet water temperature To) of the cooling
water on the downstream side (outlet) of the engine 101 is acquired
based on the outlet water temperature information transmitted from
the water temperature sensor 7a in step S2. In step S3, current
engine speed and engine torque of the engine 101 are acquired based
on engine speed information and torque information transmitted from
the engine 101, and a current speed (pump speed) of the electric WP
1 is acquired based on the pump speed information transmitted from
the electric WP 1.
[0057] Then, in step S4, an upstream temperature (inlet water
temperature Ti) of the cooling water on the upstream side (inlet)
of the engine 101 is estimated based on the acquired outlet
temperature To, engine speed, and engine torque.
[0058] Specifically, the ECU 7 first calculates a cooling loss from
the acquired engine speed and engine torque based on a cooling loss
map illustrated in FIG. 8, the cooling loss map being prestored in
a storage unit (not illustrated) of the ECU 7. The cooling loss map
depicts the cooling loss with respect to the engine torque for each
engine speed. For example, when the engine speed is about 2000 rpm,
and the engine torque is about 150 Nm, the ECU 7 calculates the
cooling loss to be about 25 kW with reference to the cooling loss
map.
[0059] Then, an engine inlet-outlet water temperature difference
.DELTA.T and an inlet water temperature Ti are estimated based on
the cooling loss and the outlet water temperature To by using
Expression (1): engine inlet-outlet water temperature difference
.DELTA.T=(cooling temperature To-inlet water temperature
Ti)=(cooling loss/(flow rate of cooling water.times.specific heat
of cooling water.times.density of cooling water)). In Expression
(1), "flow rate of cooling water" is the flow rate of cooling water
discharged from the electric WP 1, the flow rate being acquired by
the ECU 7 based on the pump speed. In Expression (1), "specific
heat of cooling water" and "density of cooling water" may simply be
approximated to 1, respectively, or may be calculated by conducting
measurement and the like in advance, respectively.
[0060] Next, in step S5, an opening of the thermostat 5 is
estimated based on the inlet water temperature Ti. Specifically,
the inlet water temperature Ti is substantially equal to the
temperature of the cooling water in the thermostat 5 arranged in
the vicinity of the engine 101 on the upstream side of the engine
101. Accordingly, the ECU 7 estimates the opening of the thermostat
5 based on the inlet water temperature Ti using the opening
characteristics map illustrated in FIG. 2, the opening
characteristics map being prestored in the storage unit of the ECU
7. The opening characteristics map depicts the opening of the
thermostat 5 with respect to the inlet water temperature Ti. For
example, when the inlet water temperature Ti is about 80.degree.
C., the opening of the thermostat 5 is estimated to be 0% with
reference to the opening characteristics map.
[0061] Next, in step S6, flow resistance of the cooling water with
respect to the flow rate of the cooling water discharged from the
electric WP 1 is estimated based on the opening of the thermostat
5. Specifically, the ECU 7 estimates the flow resistance of the
cooling water corresponding to the estimated opening of the
thermostat 5 with use of a flow resistance map illustrated in the
FIG. 3, the flow resistance map being stored in the storage unit of
the ECU 7. The flow resistance map depicts the flow resistance of
the cooling water with respect to the flow rate of the cooling
water in the electric WP 1 for each opening of the thermostat 5. As
the opening of the thermostat 5 becomes smaller, the flow
resistance of the cooling water with respect to the flow rate of
the cooling water is larger.
[0062] Then in step S7, a maximum speed of the electric WP 1 that
can close the FSV 6 (valve-closable maximum speed) is acquired
based on the flow resistance of the cooling water. Specifically,
the storage unit of the ECU 7 stores the preobtained maximum
discharge pressure of the electric WP 1 that can close the FSV 6
(valve-closable maximum discharge pressure) and a speed map
illustrated in FIG. 9. The speed map depicts the discharge pressure
of the electric WP 1 with respect to the flow rate of the cooling
water in the electric WP 1 for each speed of the electric WP 1.
[0063] The valve-closable maximum discharge pressure is calculated
in advance by acquiring, through measurement and the like, a
valve-closable maximum front-rear differential pressure upon
energization of the FSV 6 and a ratio of the front-rear
differential pressure of the FSV 6 to the pressure of the cooling
water discharged from the electric WP 1, and then by dividing the
valve-closable maximum front-rear differential pressure by the
ratio of the front-rear differential pressure. For example, when
the valve-closable maximum front-rear differential pressure upon
energization of the FSV 6 is about 0.2 kPa, and the ratio of the
front-rear differential pressure of the FSV 6 to the pressure of
the cooling water discharged from the electric WP 1 is 10%, the
valve-closable maximum discharge pressure is about 2 kPa
(=0.2/0.1).
[0064] Then, the ECU 7 acquires, as a valve-closable maximum speed,
the speed of the electric WP 1 that passes an intersection O of the
valve-closable maximum discharge pressure and the flow resistance
of cooling water on the speed map. For example, when the flow
resistance of the cooling water with respect to the flow rate of
the cooling water discharged from the electric WP 1 (illustrated
with a straight line) crosses the valve-closable maximum discharge
pressure at the intersection O as illustrated in FIG. 9, a speed
curve (=about 400 rpm) passing through the intersection O is
acquired as a valve-closable maximum speed. As illustrated in FIG.
9, as the flow resistance of the cooling water becomes larger, the
valve-closable maximum speed becomes smaller.
[0065] In step S8, valve closing time of the FSV 6 is acquired
based on the flow resistance of the cooling water. Specifically,
based on the flow rate of the cooling water corresponding to the
intersection O in FIG. 9 and on a preobtained ratio of the flow
rate of the cooling water in the cooling water channel 8b (FSV 6)
to the flow rate of the cooling water discharged from the electric
WP 1, the ECU 7 acquires the flow rate of the cooling water in the
FSV 6 when the electric WP 1 is driven at the valve-closable
maximum speed. The flow rate of the cooling water in the FSV 6 is
preferably about 1 (L/min) or less and is more preferably about 0.5
(L/min) or less.
[0066] Then, the ECU 7 acquires valve closing time of the FSV 6
from the acquired flow rate of the cooling water in the FSV 6 and
the flow resistance of the cooling water acquired in step S6, based
on a valve closing time map illustrated in FIG. 10, the valve
closing time map being prestored in the storage unit (not
illustrated) of the ECU 7. The valve closing time map depicts valve
closing time of the FSV 6 with respect to the flow rate of the
cooling water in the FSV 6 for each flow resistance of the cooling
water. The valve closing time becomes longer as the flow resistance
of the cooling water becomes larger.
[0067] In step S9, the electric WP 1 is drive-controlled so that
the electric WP 1 is driven at the acquired valve-closable maximum
speed. As a consequence, as illustrated in FIG. 5, the driving
state of the electric WP 1 is switched from the normal driving
state to the low-speed driving state, so that the flow rate of the
cooling water discharged from the electric WP 1 decreases. Then, in
step S10, the solenoid 65 of the FSV 6 is energized. Accordingly,
even in the state where the cooling water is passing, total force
made up of the electric suction force and the urging force of the
urging member 64 increases beyond the force based on the pressure
of the cooling water, because the flow rate of the cooling water is
decreased. As a result, the valve body 62 is moved in the valve
closing direction (see FIG. 4). Consequently, the FSV 6 in the
cooling water channel 8b is put in the closed state. The cooling
water with a decreased flow rate passes through the cooling water
channel 8a when the thermostat 5 is opened and through the cooling
water channel 8c other than the cooling water channel 8b. This
makes it possible to continuously pass the cooling water to the
engine 101.
[0068] Then, in step S11, after the solenoid 65 of the FSV 6 is
energized, it is determined whether or not the valve closing time
of the FSV 6 acquired in step S8 has elapsed, and the control
operation of step S11 is repeated until it is determined that the
time has elapsed. When it is determined that the valve closing time
of the FSV 6 has elapsed, the driving state of the electric WP 1 is
returned from the low-speed driving state to the normal driving
state in step S12, so that the flow rate of the cooling water
discharged from the electric WP 1 is increased. That is, in the
engine cooling device 100, the ECU 7 sets the valve closing time of
the FSV 6, and after the lapse of the valve closing time, the ECU 7
increases the flow rate of the cooling water in the cooling water
circulation channel 8. Then, the control flow of closing the FSV 6
is ended.
[0069] In this case, even in the low-speed driving period of the
electric WP 1, the electric WP 1 still continues to be driven, so
that the electric WP 1 is swiftly switched from the low-speed
driving state to the normal driving state without requiring the
period for start-up driving. Accordingly, even in the case where
the engine 101 cannot sufficiently be cooled as the electric WP 1
is in the low-speed driving state, such as in the case of driving
the engine 101 with a high load, the electric WP 1 is swiftly
switched to the normal driving state, so that the engine 101 is
swiftly and sufficiently cooled.
[0070] As a consequence, the following effects can be obtained in
the present embodiment.
[0071] In the present embodiment, as described in the foregoing,
there is provided the ECU 7 that executes control, at the time of
closing the FSV 6 in the cooling water channel 8b not going through
the radiator 2, to cut off passage of the cooling water in the
cooling water channel 8b by closing the FSV 6 while the cooling
water is passing at a decreased flow rate. Accordingly, since the
FSV 6 is closed while the cooling water is passing, the cooling
water can be passed into the engine cooling device 100 (the cooling
water channel 8a going through the radiator 2 (when the thermostat
5 is opened) and the cooling water channel 8c) even in the case of
closing the FSV 6 in the cooling water channel 8b not going through
the radiator 2. This makes it possible to suppress the situation
where the cooling water is not passed to the engine 101. As a
result, in the case of closing the FSV 6 in the cooling water
channel 8b not going through the radiator 2, the engine 101 can
continue to be cooled by the passing cooling water, which makes it
possible to prevent the engine 101 during driving from becoming
high in temperature. When the valve body 62 is moved in the valve
closing direction, cooling water is passed at a decreased flow
rate, which can suppress increase in the force to move the valve
body 62 in the valve closing direction against the passing cooling
water. This makes it possible to prevent the necessary electric
suction force from increasing in the FSV 6. Therefore, increase in
electric power necessary for closing the FSV 6 can be suppressed,
while upsizing of the FSV 6 to generate larger electric suction
force can also be suppressed.
[0072] In the present embodiment, the FSV 6 is configured to move
the valve body 62 in the valve closing direction with the urging
force of the urging member 64 and the electric suction force, while
the electric WP 1 is driven. Accordingly, the valve body 62 can
easily be moved in the valve closing direction in proportion to the
urging force given by the urging member 64 against the passing
cooling water, which makes it possible to prevent the flow rate of
the cooling water from being significantly decreased for the
purpose of closing the FSV 6 in the cooling water channel 8b not
going through the radiator 2. As a result, even in the state where
the flow rate of the cooling water is decreased, the cooling water
can sufficiently be passed into the engine cooling device 100 (the
cooling water channel 8a going through the radiator 2 (when the
thermostat 5 is opened) and the cooling water channel 8c).
[0073] In the present embodiment, the ECU 7 is configured to
execute control to close the FSV 6 in the cooling water channel 8b
by acquiring the valve-closable maximum speed of the electric WP 1
based on at least flow resistance of the cooling water and moving
the valve body 62 while the electric WP 1 is driven at a speed
equal to the valve-closable maximum speed. Accordingly, since the
valve body 62 is moved while the electric WP 1 is driven at the
valve-closable maximum speed, the FSV 6 in the cooling water
channel 8b not going through the radiator 2 can reliably be closed,
while the cooling water is passing into the engine cooling device
100 (the cooling water channel 8a going through the radiator 2
(when the thermostat 5 is opened) and the cooling water channel
8c). Moreover, since the valve-closable maximum speed of the
electric WP 1 is acquired based on the flow resistance of the
cooling water relating to the valve-closable maximum speed of the
electric WP 1, the FSV 6 can more reliably be closed based on the
precise valve-closable maximum speed of the electric WP 1.
[0074] In the present embodiment, the ECU 7 is configured to
estimate the flow resistance of the cooling water based on the
opening of the thermostat 5. Accordingly, more precise
valve-closable maximum speed of the electric WP 1 can be acquired
based on the appropriately estimated flow resistance of the cooling
water. When the thermostat 5 is in the opened state, the cooling
water can be passed to the engine 101 by passing the cooling water
through the cooling water channel 8a even in the case where passage
of the cooling water in the cooling water channel 8b is cut off. It
also becomes possible to effectively cool the cooling water having
a high temperature by passing the cooling water to the radiator 2
in the first cooling water channel 8a. When the thermostat 5 is in
the closed state, it signifies that cooling the engine 101 during
driving with the cooling water having a low temperature is not
preferable, as in the case of engine warm-up. Accordingly, by
blocking the passage of the cooling water to the radiator 2 in the
first cooling water channel 8a, cooling of the cooling water in the
radiator 2 can be prevented, which can suppress excessive cooling
of the engine 101.
[0075] In the present embodiment, even in the case where the
electric WP 1 is an electrically-operated water pump including the
brushless sensorless motor 1a, the electric WP 1 is driven, at the
time of closing the FSV 6 in the engine cooling device 100, to
decrease the flow rate of the cooling water, which eliminates the
necessity of extra time like the period for start-up driving. As a
result, even in the case where the electric WP 1 includes the
brushless sensorless motor 1a, it becomes possible to prevent the
situation where passage of the cooling water to the engine 101 is
stopped.
[0076] In the present embodiment, after closing of the FSV 6 in the
cooling water channel 8b is completed, the ECU 7 executes control
to increase the flow rate of cooling water with the electric WP 1.
Therefore, the engine 101, the oil of the oil cooler 4, and the
like can effectively be cooled by the cooling water.
[0077] In the present embodiment, the heater core 3 that exchanges
heat with cooling water is arranged in the cooling water channel 8b
where the FSV 6 is arranged.
[0078] Accordingly, when the FSV 6 is in the opened state, the
inside of the vehicle can be heated with the heat recovered from
the cooling water in the heater core 3, so that the heat of the
cooling water can efficiently be used. Moreover, passage of the
cooling water warmed by the engine 101 to the heater core 3
(cooling water channel 8b) can be cut off by putting the FSV 6 into
the closed state, so that the cooling efficiency inside the vehicle
can be enhanced.
[0079] In the present embodiment, the oil cooler 4 that exchanges
heat with the cooling water is arranged in the cooling water
channel 8c. Accordingly, oil can be cooled by using the cooling
water circulating through the cooling water circulation channel 8.
Moreover, when the FSV 6 is put in the closed state, passage of the
cooling water through the heater core 3 (cooling water channel 8b)
can be cut off and the flow rate of the cooling water passing on
the side of the oil cooler 4 (cooling water channel 8c) can be
increased. Hence, the cooling efficiency of the oil in the oil
cooler 4 can be enhanced.
[0080] In the present embodiment, the ECU 7 is configured to
acquire the valve-closable maximum speed of the electric WP 1 based
on the valve-closable maximum discharge pressure of the cooling
water in the electric WP 1 and the flow resistance of the cooling
water. Accordingly, the valve-closable maximum speed of the
electric WP 1 can reliably be acquired.
[0081] In the present embodiment, the ECU 7 is configured to
execute control to set the period (valve closing time) until
closing of the FSV 6 is completed in accordance with the flow
resistance of the cooling water and to increase the flow rate of
the cooling water by the electric WP 1 after the lapse of the set
valve closing time of the FSV 6. Accordingly, it becomes possible
to prevent the flow rate of the cooling water passing through the
FSV 6 from increasing in the state where the FSV 6 is not fully
closed. As a result, the situation where the cooling water
continues to pass through the cooling water channel 8b due to
incomplete closing of the FSV 6 can be suppressed.
[0082] In the present embodiment, the ECU 7 is configured to
estimate the upstream temperature (inlet water temperature Ti) of
the cooling water on the upstream side of the engine 101 based on
the downstream temperature (outlet water temperature To) of the
cooling water on the downstream side of the engine 101 detected by
the water temperature sensor 7a and on the cooling loss in the
engine 101, and to estimate the opening of the thermostat 5
arranged on the upstream side of the engine 101 based on the inlet
water temperature Ti. Accordingly, the opening of the thermostat 5
can be estimated using the detection result (outlet water
temperature To) of the water temperature sensor 7a that is
generally arranged on the downstream side of the engine 101. This
eliminates the necessity of arranging another water temperature
sensor separately from the water temperature sensor 7a on the
upstream side of the engine 101. Thus, the number of component
members can be reduced.
[0083] It should be understood that the embodiment disclosed is in
all respects illustrative and is not considered as the basis for
restrictive interpretation. The scope of the present invention is
defined not by the foregoing description of the embodiment but by
the range of appended claims. Furthermore, all changes
(modifications) which come within the range of the claims and
meaning and the range of equivalency thereof are therefore to be
embraced therein.
[0084] For example, described in the embodiment is an example of
the engine cooling device 100 configured to acquire, at the time of
closing the FSV 6, the valve-closable maximum speed based on
various parameters, such as an outlet water temperature, and to
perform low-speed driving of the electric WP 1 at the acquired
valve-closable maximum speed. However, the present invention is not
limited thereto. In the present invention, the engine cooling
device may be configured to close the FSV at least with electric
suction force while the flow rate of the cooling water is in a
decreased state. For example, the engine cooling device may be
configured to perform low-speed driving of the electric WP at a
preset low speed at the time of closing the FSV. This makes it
unnecessary to calculate the valve-closable maximum speed, and
therefore the control load of the ECU can proportionally be
reduced.
[0085] Moreover, although an example in which the ECU 7 performs
low-speed driving of the electric WP 1 at the acquired
valve-closable maximum speed is described in the embodiment, the
present invention is not limited thereto. In the present invention,
the ECU may perform low-speed driving of the electric WP at speeds
less than the valve-closable maximum speed. In this case, low-speed
driving of the electric WP is preferably performed at speeds that
are less than the valve-closable maximum speed and are in the
vicinity of the valve-closable maximum speed. As a result, it
becomes possible to secure a sufficient flow rate of the cooling
water while the electric WP is in the low-speed driving state and
to achieve more reliable closing of the FSV.
[0086] Although an example of estimating each of the inlet water
temperature Ti, the opening of the thermostat 5, and the flow
resistance of the cooling water is described in the embodiment, the
present invention is not limited thereto. The present invention may
be configured so that the inlet water temperature, the opening of
the thermostat, and the flow resistance of cooling water may
directly be detected using detection units such as sensors,
respectively. In the case of directly detecting the flow resistance
of the cooling water, it is not necessary to acquire (estimate) the
inlet water temperature and the opening of the thermostat. In the
case of directly detecting the opening of the thermostat, it is not
necessary to acquire (estimate) the inlet water temperature.
[0087] An example in which the ECU 7 calculates the valve closing
time of the FSV 6 based on the flow resistance of the cooling water
and on the flow rate of the cooling water in the FSV 6 is described
in the embodiment. However, the present invention is not limited
thereto. In the present invention, the ECU may use a preset valve
closing time as the valve closing time of the FSV. This makes it
unnecessary to calculate the valve closing time, and therefore the
control load of the ECU can proportionally be reduced.
[0088] Although an example of using the electric WP 1 as a water
pump is described in the embodiment, the present invention is not
limited thereto. For example, a non-electric water pump which
receives rotation driving force delivered from an engine crankshaft
or the like may be used as the water pump. In this case, if a
clearance between an impeller inside the water pump and a cover is
configured to be adjustable, the flow rate of the cooling water
discharged from the water pump can be controlled. The flow rate of
the cooling water discharged from the water pump can also be
controlled by controlling the rotation driving force delivered from
the crankshaft with use of a member capable of controlling the
driving force, such as a gear transmission and a clutch.
[0089] Although an example in which the electric WP 1 is an
electrically-operated water pump including the brushless sensorless
motor la is described in the embodiment, the present invention is
not limited thereto. The present invention may be configured so
that the electric WP includes, instead of the brushless sensorless
motor, a brushless motor equipped with a sensor that detects the
position of a rotor, or a motor with a brush.
[0090] Although an example in which the FSV 6 (solenoid valve)
includes the urging member 64 in addition to the solenoid 65 is
described in the embodiment, the present invention is not limited
thereto. In the present invention, the solenoid valve may be
configured so that the valve body moves in the valve closing
direction at least with the electric suction force. That is, the
solenoid valve may be configured without the urging member.
[0091] In the embodiment, an example is described in which the
thermostat 5 is arranged in the cooling water channel 8a (first
cooling water channel) where the radiator 2 is arranged, the heater
core 3 is arranged in the cooling water channel 8b (second cooling
water channel) where the FSV 6 is arranged, and the oil cooler 4 is
arranged in the cooling water channel 8c (third cooling water
channel). However, the present invention is not limited thereto. In
the present invention, a heat exchanger may also be arranged in
addition to the radiator in the first cooling water channel.
Moreover, the thermostat does not need to be arranged in the first
cooling water channel. A heat exchanger other than the heater core
may additionally be arranged in the second cooling water channel,
or another heat exchanger may be arranged in place of the heater
core, or the heat exchanger including the heater core itself does
not need to be arranged. Moreover, a heat exchanger other than the
oil cooler may additionally be arranged in the third cooling water
channel, or another heat exchanger may be arranged in place of the
oil cooler, or the heat exchanger including the oil cooler itself
does not need to be arranged. Here, as a heat exchanger other than
the heater core and the oil cooler, exhaust gas recirculation (EGR)
coolers, exhaust heat recovery devices, mission coolers, inverter
coolers and the like may be used.
[0092] Although an example of providing the cooling water channel
8c (third cooling water channel) where the oil cooler 4 is arranged
is described in the embodiment, the present invention is not
limited thereto. In the present invention, the third cooling water
channel does not need to be arranged.
[0093] Although an example of mounting the engine cooling device
100 on the vehicle is described in the embodiment, the present
invention is not limited thereto. The engine cooling device of the
present invention may be provided in a boat having an engine
attached thereto, or the like.
* * * * *