U.S. patent application number 09/832088 was filed with the patent office on 2001-11-15 for apparatus and method for controlling duty ratio for cooling fan associated motor of vehicle.
This patent application is currently assigned to NISSAN MOTOR CO., LTD.. Invention is credited to Furukawa, Tomofumi, Kobayashi, Kazuhira.
Application Number | 20010039926 09/832088 |
Document ID | / |
Family ID | 18646507 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010039926 |
Kind Code |
A1 |
Kobayashi, Kazuhira ; et
al. |
November 15, 2001 |
Apparatus and method for controlling duty ratio for cooling fan
associated motor of vehicle
Abstract
In apparatus and method for controlling a cooling fan associated
motor at a pulse duty ratio, the cooling fan is revolved by the
cooling fan associated motor to cool a radiator of a vehicular
engine coolant and a condenser of a refrigerant of a vehicular air
conditioner and the duty ratio for the cooling fan associated motor
is controlled in such a manner that a sum of a torque required for
a generator to drive the cooling fan associated motor and a torque
required to drive a compressor of the air conditioner is minimized
while satisfying a control demand for a coolant temperature and a
refrigerant pressure so that the cooling fan associated motor is
driven at the duty ratio.
Inventors: |
Kobayashi, Kazuhira;
(Kanagawa, JP) ; Furukawa, Tomofumi; (Kanagawa,
JP) |
Correspondence
Address: |
McDERMOTT, WILL & EMERY
600 13th Street, N.W.
Washington
DC
20005-3096
US
|
Assignee: |
NISSAN MOTOR CO., LTD.
|
Family ID: |
18646507 |
Appl. No.: |
09/832088 |
Filed: |
April 11, 2001 |
Current U.S.
Class: |
123/41.12 |
Current CPC
Class: |
F01P 2060/14 20130101;
F01P 2023/00 20130101; F01P 7/048 20130101; B60H 2001/3248
20130101; F01P 2005/025 20130101; F01P 2005/046 20130101; B60H
2001/3255 20130101; B60H 1/3208 20130101; F01P 2025/04 20130101;
B60H 1/3205 20130101; B60H 2001/3277 20130101; F01P 2025/64
20130101; F01P 2025/08 20130101; B60H 2001/3266 20130101 |
Class at
Publication: |
123/41.12 |
International
Class: |
F01P 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 11, 2000 |
JP |
2000-138979 |
Claims
What is claimed is:
1. A method for controlling a cooling fan associated motor at a
pulse duty ratio, the cooling fan being revolved by the cooling fan
associated motor to cool a radiator of a vehicular engine coolant
and a condenser of a refrigerant of a vehicular air conditioner,
the method comprising: controlling the duty ratio for the cooling
fan associated motor in such a manner that a sum of a torque
required for a generator to drive the cooling fan associated motor
and a torque required to drive a compressor of the air conditioner
minimized while satisfying a control demand for a coolant
temperature and a refrigerant pressure; and driving the cooling
associated motor.
2. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio, the cooling fan being revolved by the cooling fan
associated motor to cool a radiator of a vehicular engine coolant
and a condenser of a refrigerant of a vehicular air conditioner,
the apparatus comprising: a controller to control the duty ratio
for the cooling fan associated motor in such a manner that a sum of
a torque required for a generator to drive the cooling fan
associated motor and a torque required to drive a compressor of the
air conditioner is minimized while satisfying a control demand for
a coolant temperature and a refrigerant pressure; and a driver to
drive the cooling associated motor at the duty ratio.
3. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio as claimed in claim 2, wherein the controller
comprises: a first command value calculating section that
calculates a first command value of the duty ratio in accordance
with the refrigerant pressure; a second command value calculating
section that calculates a second command value of the duty ratio in
accordance with the coolant pressure; a first target value setting
section that sets one of the first and second command values which
is larger than the other to a first target value of the duty ratio;
a second target value setting section that calculates a sum of a
torque of a generator and that of a compressor and sets the duty
ratio which minimizes the sum as a second target value setting
section; and a duty ratio determining section that determines the
final duty ratio from one of the first and second target values
which is larger than the other and wherein the controller controls
the cooling fan associated motor at the final duty ratio.
4. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio as claimed in claim 3, wherein the first command
value calculating section calculates the first command value on the
basis of a first map representing a relationship between the
refrigerant pressure and the duty ratio, the second command value
calculating section calculates the second command value on the
basis of a second map representing a relationship between the
coolant temperature and the duty ratio, the second target value
setting section calculates the torque of the generator on the basis
of third maps representing the relationship between the duty ratio
and a generator current of the generator and the generator current
and the torque of the generator and calculates a torque of the
compressor on the basis of the map representing the relationship
between the duty ratio and the compressor.
5. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio as claimed in claim 4, wherein the first map has
such a characteristic that when the refrigerant pressure falls in a
range equal to or lower than a first predetermined value (P1), the
duty ratio constantly indicates about 30%, the duty ratio is raised
in proportion to the refrigerant pressure when the refrigerant
pressure falls in a range exceeding the first predetermined value
(P1) but equal to or below a second predetermined value (P2), and
the duty ratio indicates constantly 100% when P1>P2.
6. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio as claimed in claim 5, wherein the second map has
such a characteristic that the duty ratio indicates 0% when the
coolant temperature is equal to or lower than a third predetermined
value (T1), is increased in proportion to the coolant temperature
when the coolant temperature falls in a range exceeding the third
predetermined value (T1) but equal to or below a fourth
predetermined value (T2), and indicates constantly 100% when the
coolant temperature is in excess of the fourth predetermined value
(T2).
7. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio as claimed in claim 6, wherein the third maps
comprises a fifth map having such a characteristic that in
proportion to the generator current, the duty ratio is increased
and a sixth map having such a characteristic that in proportion to
the generator current, the torque of the generator is increased for
each engine speed.
8. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio as claimed in claim 7, wherein the fourth map has
a characteristic that, under predetermined compressor revolution
speed and outer temperature outside the vehicle, the required
torque of the compressor is decreased as the duty ratio is
increased.
9. An apparatus for controlling a cooling fan associated motor at a
pulse duty ratio as claimed in claim 8, wherein the cooling fan
motor comprises a plurality of motors, each cooling fan being
attached onto a rotor axis of the corresponding one of the motors
and being faced toward the condenser of the vehicular air
conditioner and the radiator juxtaposed to the condenser, both
condenser and radiator being cooled by the cooling fan motor.
10. An apparatus for controlling a cooling fan associated motor at
a pulse duty ratio as claimed in claim 9, wherein the driver drives
the plurality of motors at the same duty ratio and at mutually
different frequencies.
11. An apparatus for controlling a cooling fan associated motor at
a pulse duty ratio, the cooling fan being revolved by the cooling
fan associated motor to cool a radiator of a vehicular engine
coolant and a condenser of a refrigerant of a vehicular air
conditioner, the apparatus comprising: controlling means for
controlling the duty ratio for the cooling fan associated motor in
such a manner that a sum of a torque required for a generator to
drive the cooling fan associated motor and a torque required to
drive a compressor of the air conditioner is minimized while
satisfying a control demand for a coolant temperature and a
refrigerant pressure; and driving means for driving the cooling
associated motor at the duty ratio.
Description
BACKGROUND OF THE INVENTION
[0001] a) Field of the Invention
[0002] The present invention relates generally to controlling
apparatus and method for controlling a duty ratio for a cooling fan
associated motor (hereinafter, also simply referred to as a fan
motor) of an automotive vehicle, particularly, relates to the
controlling apparatus and method for controlling the duty ratio of
the cooling fan associated motor of an engine cooling radiator and
a condenser of a vehicular air conditioner.
[0003] b) Description of the related art
[0004] A Japanese Patent Application First Publication No. Heisei
11-229876 published on Aug. 24, 1999 exemplifies a previously
proposed automotive vehicle cooling system having a cooling fan
associated motor to cool a radiator and a condenser of a vehicular
air conditioner through the cooling fans to cool a radiator of an
engine and a condenser of the air conditioner.
[0005] A Pulse Width Modulation (PWM) is carried out by detecting a
refrigerant pressure of the air conditioner and a coolant
temperature and an air conditioner and calculating a duty ratio of
the cooling fan in accordance with the coolant temperature and the
refrigerant pressure.
SUMMARY OF THE INVENTION
[0006] However, since, in the above-described Japanese Patent
Application Publication No. Heisei 11-229876, the duty ratio
control for the motor is carried out with only the coolant
temperature and a performance of the air conditioner taken into
account, a fuel consumption of the whole vehicle often becomes
worsened depending upon a situation of a motor operation.
[0007] In addition, since the cooling fan associated motor is
constituted by two or more cooling fans and associated motors, a
beat tone is often developed in accordance with individual product
difference or fan profile difference when two or more motors are
controlled at the same frequencies.
[0008] It is, hence, an object of the present invention to provide
controlling apparatus and method for controlling a duty ratio of
each cooling fan associated motor of an automotive vehicle.
[0009] According to one aspect of the present invention, there is
provided a method for controlling a cooling fan associated motor at
a pulse duty ratio, the cooling fan being revolved by the cooling
fan associated motor to cool a radiator of a vehicular engine
coolant and a condenser of a refrigerant of a vehicular air
conditioner, the method comprising: controlling the duty ratio for
the cooling fan associated motor in such a manner that a sum of a
torque required for a generator to drive the cooling fan associated
motor and a torque required to drive a compressor of the air
conditioner is minimized while satisfying a control demand for a
coolant temperature and a refrigerant pressure; and driving the
cooling associated motor.
[0010] According to another aspect of the present invention, there
is provided an apparatus for controlling a cooling fan associated
motor at a pulse duty ratio, the cooling fan being revolved by the
cooling fan associated motor to cool a radiator of a vehicular
engine coolant and a condenser of a refrigerant of a vehicular air
conditioner, the apparatus comprising: a controller to control the
duty ratio for the cooling fan associated motor in such a manner
that a sum of a torque required for a generator to drive the
cooling fan associated motor and a torque required to drive a
compressor of the air conditioner is minimized while satisfying a
control demand for a coolant temperature and a refrigerant
pressure; and a driver to drive the cooling associated motor at the
duty ratio.
[0011] This summary of the invention does not necessarily describe
all necessary features so that the invention may also be a
sub-combination of these described features.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1A is a schematic circuit block diagram of a vehicular
cooling system to which a preferred embodiment of a cooling fan
associated motor controlling apparatus is applicable.
[0013] FIG. 1B is a schematic circuit block diagram of a fan motor
controller and an engine controller shown in FIG. 1A.
[0014] FIG. 2A is a characteristic graph of a map representing a
relationship between a duty ratio for the cooling fan associated
motor and a refrigerant pressure.
[0015] FIG. 2B is a characteristic graph of a map representing a
relationship between the duty ratio and a coolant temperature.
[0016] FIG. 3 is a characteristic graph of a map representing the
duty ratio and a generator current.
[0017] FIG. 4 is a characteristic graph of maps representing
relationships between the generator's torque and generator current
with engine speed as a parameter.
[0018] FIG. 5 is a characteristic graph of maps representing a
torque of a compressor and duty ratio with the engine speed and
outer temperature as parameters.
[0019] FIG. 6 is an operational flowchart for explaining an
operation of the cooling fan motor controller shown in FIG. 1A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Reference will hereinafter be made to the drawings in order
to facilitate a better understanding of the present invention.
[0021] FIG. 1A shows a schematic circuit block diagram of a
vehicular cooling system to which a cooling fan duty ratio
controlling apparatus in a preferred embodiment according to the
present invention is applicable.
[0022] An engine speed sensor 13 and a coolant temperature sensor
14 are connected to an engine controller 12 to control an engine
operation of an engine 11. The engine speed sensor 13 detects an
engine speed and the coolant temperature 14 to detect an engine
coolant temperature.
[0023] An engine coolant of the engine 11 is cooled with a radiator
15 which is arranged within an engine compartment. A condenser 16
of the air-conditioner A/C is disposed in a vehicular
forward/rearward (longitudinal) direction together with the
radiator 15.
[0024] A cooling fan couple 17 (17a, 17b) is associated with each
corresponding motor at a rear side of the vehicle. The condenser 16
and radiator 15 are cooled in accordance with an outside air and
the cooling fan couple 17 (17a, 17b).
[0025] This cooling fan couple 17 are controlled by means of a
control unit 18. The control unit 18 includes: a motor fan
controller 19; and a pair of PWM drivers 20 (20a, 20b) connected
across each of the fan associated motors 17 (17a, 17b).
[0026] This cooling fan couple 17 are controlled by means of a
control unit 18.
[0027] The control unit 18 includes: a motor fan controller 19; and
a pair of PWM drivers 20 (20a, 20b) connected across each of fan
associated motors 17 (17a, 17b).
[0028] The motor fan controller 19 is connected to engine
controller 12 to read the engine speed Ne and coolant temperature
Tw. A pressure sensor 21 and an outer temperature sensor 22 are
connected to fan motor controller 19 to read a refrigerant pressure
of an air conditioner and to read an outer air temperature outside
the vehicle.
[0029] The fan motor controller 19 calculates a duty ratio to
control a drive of fan motor couple 17 (17a, 17b) and outputs the
calculated duty ratio to corresponding PWM driver 20 (20a,
20b).
[0030] To calculate the duty ratio, use is made of previously
prepared maps of a map representing a relationship between the duty
ratio (%) and a pressure of the refrigerant for one motor (17a,
17b) shown in FIG. 2A, a map representing the relationship between
the duty ratio (%) and the coolant temperature shown in FIG. 2B, a
map representing a relationship between the duty ratio of the motor
fan and a power generating current of the power generator shown in
FIG. 3, a map representing the relationship between the power
generating current of the power generator and the torque thereof
shown in FIG. 4, and a map representing the relationship between
the power generating current of the power generator shown in FIG. 4
and a torque of a compressor.
[0031] The PWM driver couple 20 drives the corresponding fan motor
17 with a battery voltage as a power supply upon receipt of an
output of fan motor controller 19. A battery 23 charges via
regulator 25 with an AC power generator 24 driven by an engine.
[0032] It is noted that FIG. 1B shows an internal circuit block
diagram of fan motor controller 19 and engine controller 12 and, as
shown in FIG. 1B, fan motor controller 19 includes a microcomputer
having a CPU 19a(Central Processing Unit), ROM 19b(Read Only
Memory), RAM 19c(Random Access memory), an Input Port 19d, an
Output Port 19e, and a common bus. Engine controller 12 includes
the microcomputer having a CPU 12a, a ROM 12b, a RAM 12c, an Input
Port 12d, and a common bus in the same manner as fan motor
controller 19.
[0033] Next, FIG. 6 shows an operational flowchart representing a
control flow with the fan motor controller. The control operation
in accordance with the flowchart shown in FIG. 6 is executed
whenever an engine ignition switch is turned on and the engine is
started.
[0034] At a step 101, fan motor controller 19 reads the engine
speed Ne and the outer temperature Temp from engine controller
12.
[0035] At a step 102, fan motor controller 19 checks to see if a
power switch of the air conditioner is turned to ON or OFF.
[0036] If A/C ON (yes), namely, the air conditioner is being
operated at step S102, the routine goes to a step S103.
[0037] If A/C is turned to OFF (No), namely, the air conditioner is
not operated, the routine goes to a step 116.
[0038] At step 103, fan motor controller 19 reads refrigerant
pressure from refrigerant pressure sensor 21.
[0039] At a step 104, fan motor controller 19 reads coolant
temperature Tw from engine controller 12.
[0040] At a step 105, fan motor controller 19 calculates a first
command value X of a duty ratio for cooling fan associated motor 17
(17a, 17b) to satisfy a demand to the performance of the air
conditioner using a map representing a relationship between the
refrigerant pressure and duty ratio of fan motor shown in FIG.
2A.
[0041] In FIG. 2A, the map shows that such a characteristic that
the duty ratio is constantly at about 30% when the refrigerant
pressure is equal to or below P1, the duty ratio is raised in
proportion to the refrigerant pressure from P1 to P2, and the
constant duty ratio of 100% is continued when exceeding P2.
[0042] At a step 106, fan motor controller 19 calculates a second
command value Y of a duty ratio for the fan motor to satisfy the
demand to the coolant temperature Tw using a map representing the
relationship between the coolant temperature and duty ratio of the
motor fan shown in FIG. 2B.
[0043] In FIG. 2B, the map shows that such a characteristic is set
that the fan motor is not driven with the duty ratio set to 0% when
the coolant temperature is equal to or lower than T1, the duty
ratio is raised in proportion to coolant temperature Tw when the
coolant temperature Tw ranges from T1 to (T1 exclusive) to T2, and
duty ratio of 100% is continued constantly when Tw>T2.
[0044] At a step 107, fan motor controller 19 compares first
command value X with second command value Y to determine if
X>Y.
[0045] If first command value X is larger than second command value
Y (X>Y)(Yes) at step 107, the routine goes to a step 108.
[0046] If X<Y (No) at step 107, the routine goes to a step
109.
[0047] At step 108, fan motor controller 19 sets first command
value X to a first target value D1 of duty ratio of fan motor
17(D1=X).
[0048] At a step 109, fan motor controller 19 sets the second
command value to a second target value D2 of duty ratio of the fan
motor. That is to say, if the duty ratio for command values X and Y
which is larger than the other from among first and second command
values X and Y, the fan motor can satisfy the demand of both
coolant temperature and performance if the air conditioner.
[0049] At a step 110, fan motor controller 19 calculates a power
generation current I1 of power generator from first target value D1
using the map representing a relationship between the duty ratio of
the fan motor and power generating current of the power generator
shown in FIG. 3.
[0050] In FIG. 3, the map shows such a characteristic that the
power generation current at its duty ratio required to drive the
fan becomes large.
[0051] At a step 111, fan motor controller 19 calculates a torque
Ti1 of the power generator from power generator current I1 using
the map representing the power generating current of the generator
shown in FIG. 4 and the torque.
[0052] In FIG. 4, the map shows such a characteristic that, at a
predetermined engine speed (namely, the revolution speed of the
power generator), the torque requires to generate the current of
the power generator in proportion to the magnitude of the power
supply current of the power generator and prepared for each engine
speed.
[0053] At a step 112, fan motor controller 19 calculates a torque
Tc1 of compressor using a map representing the duty ratio of the
fan motor and torque of the compressor shown in FIG. 5. The map
shown in FIG. 5 represents the relationship between the duty ratio
of the fan motor 17 and the torque of the compressor when the
condenser is cooled by means of the fan motor driven at the duty
ratio. As the duty ratio becomes large, the required torque is
decreased. Such a map as described above is prepared for each
combination of the engine speed and outer temperature. At a step
113, a total of generator's torque Ti1 and compressor's torque Te1
is set to T1.
[0054] At a step 114, fan motor controller 19 calculates second
target value D2 of the fan motor duty ratio such that a sum (total)
of the generator's torque and compressor's torque becomes minimized
with the operation states of the generator and compressor taken
into account.
[0055] In FIG. 4, the map shows such a characteristic that, at a
predetermined engine speed (namely, the revolution speed of the
power generator), the torque requires to generate the current of
the power generator in proportion to the magnitude of the power
supply current of the power generator and prepared for each engine
speed.
[0056] At a step 112, fan motor controller 19 calculates a torque
Tc1 of compressor using a map representing the duty ratio of
cooling fan associated motor 17 and torque of the compressor shown
in FIG. 5.
[0057] The map shown in FIG. 5 represents the relationship between
the duty ratio of the fan motor and the torque of the compressor
when the condenser is cooled by means of the fan motor driven at
the duty ratio. As the duty ratio becomes large, the required
torque is decreased. Such a map as described above is prepared for
each combination of the engine speed and outer temperature.
[0058] At a step 113, a total of generator torque Ti1 and
compressor torque Tc1 is set to T1. At a step 114, fan motor
controller 19 calculates second torque value D2 of the fan motor
duty ratio such that the total of the generator's torque and
compressor's torque becomes minimized with the operation states of
the generator and compressor taken into account.
[0059] At a step 114, fan motor controller 19 calculates second
torque value D2 of the fan motor duty ratio such that the total of
the generator's torque and compressor's torque becomes minimized
with the operation states of the generator and compressor taken
into account.
[0060] Specifically, with the duty ratio of the motor fan varied
gradually from first target value D1, generator current I2 of the
power generator is calculated in the same manner as step 110 and,
thereafter, torque Ti2 of the power generator is calculated in the
same manner as step 111 and torque Tc2 of the compressor is
calculated in the same manner as step 112.
[0061] Then, after total of T2 between Ti1 and Ti2 is calculated,
the duty ratio of the fan motor when T2<T1 is derived. The duty
ratio when T2 is minimized is set to a second target value D2. At a
step 115, fan motor controller 19 compares first target value D1
with second target value D2.
[0062] If second target value D2 is equal to or larger than first
target value D1, the routine goes to a step 119. If second target
value D2 is smaller than first target value D1 (D2<D1) at step
115 (No), the routine goes to a step 120.
[0063] At step 119, fan motor controller 19 outputs the duty ratio
of D2 to PWM driver 20 (20a, 20b). In this case, since the load
torque imposed on the engine is minimized and the duty ratio
(namely, D2) of fan motor 17 which does not affect a performance of
the air conditioner is used, operation states of the power
generator and compressor are minimized.
[0064] At a step 120, fan motor controller 19 outputs the duty
ratio of D1 to PWM driver 20 (20a, 20b).
[0065] It is noted that control unit 18 drives the two fan motors
17 (17a, 17b) at mutually different frequencies when the fan motor
is controlled at the duty ratio of D1 and D2.
[0066] It is also noted that control unit 18 drives two fan motors
17 (17a, 17b) at mutually different frequencies when the fan motor
is controlled at the duty ratio of D1 or D2.
[0067] On the other hand, if the power switch of the air
conditioner is turned to OFF at step 102 (No), motor fan controller
19 reads coolant temperature Tw from engine controller 12.
[0068] At a step 117, motor fan controller 19 calculates second
command value Y from coolant temperature read at step 116. it is
noted that since the air conditioner switch is turned to OFF, first
command value X is not calculated.
[0069] At a step 118, second command value Y is set to first target
value D1. As described above, since the air conditioner switch is
turned to OFF, second target value D2 with the operation states of
the compressor taken into account is not calculated.
[0070] Thereafter, the routine goes from step 118 to step 120. It
is noted that after the execution of step 119 or step 120, the
routine returns to a step 101 and the present control is
repeated.
[0071] In this embodiment, steps 103 and 105 are constituted by
first command value calculating means, steps 104 and 106 are
constituted by second command value calculating means, steps 107
through 109 are constituted by first target value setting means,
steps 110 through 114 are constituted by second target value
setting means, and steps 115, 119 and 120 are constituted by duty
ratio determining means.
[0072] In the preferred embodiment described above, the total of
the power generator torque and compressor torque is minimized while
the demand to the coolant temperature and air conditioner
performance satisfied. Since two fan motors 17 (17a, 17b) are
controlled at different frequencies, the fan motor controller can
prevent the beat tone from being developed depending upon the
individual difference between the respective motors and difference
in the fan profiles.
[0073] The entire contents of a Japanese Patent Application No.
2000-138979 (filed in Japan on May 11, 2000) are herein
incorporated by reference. Although the invention has been
described above by reference to certain embodiment of the
invention, the invention is not limited to the preferred embodiment
described above.
[0074] For example, although, in the preferred embodiment, the
number of fan motors 17 are two, the number of fan motors may be
one or three or more. Although, in the preferred embodiment, the
engine speed Ne and coolant temperature Tw can be read through
engine controller 12, fan motor controller 19 may directly be read
thereat. A stream of control by fan motor controller 19 is not only
limited to the case of the preferred embodiment in which the
operation is advanced in accordance with the flowchart of FIG. 6
but also may be such that the sequence of steps 104 and 105 is
reversed and that the sequence on the calculations of first command
value X based on pressure refrigerant and of second command value Y
based on coolant temperature.
[0075] Modifications and variations of the embodiments described
above will occur to those skilled in the art in the light of the
above teachings.
[0076] The scope of the invention is defined with reference to the
following claims.
* * * * *