U.S. patent application number 12/032194 was filed with the patent office on 2009-08-20 for internal combustion engine with variable speed coolant pump.
Invention is credited to John P. Bilezikjian, Thomas J. Cusumano, Elmer S. Foster, JR., Ken J. Jackson, Valerie A. Nelson, Brian D. Rutkowski, William S. Schwartz.
Application Number | 20090205588 12/032194 |
Document ID | / |
Family ID | 40953939 |
Filed Date | 2009-08-20 |
United States Patent
Application |
20090205588 |
Kind Code |
A1 |
Bilezikjian; John P. ; et
al. |
August 20, 2009 |
INTERNAL COMBUSTION ENGINE WITH VARIABLE SPEED COOLANT PUMP
Abstract
An internal combustion engine has a variable speed coolant pump
which is operated at a variable duty-cycle at lower coolant
temperatures, while transitioning to a predetermined fixed speed
during a final warmup period of operation, and finally to a
select-speed operation at one of a selected number of steady state
operating speeds selected as a function of at least engine
load.
Inventors: |
Bilezikjian; John P.;
(Canton, MI) ; Cusumano; Thomas J.; (Royal Oak,
MI) ; Nelson; Valerie A.; (Livonia, MI) ;
Jackson; Ken J.; (Dearborn, MI) ; Foster, JR.; Elmer
S.; (Ypsilanti, MI) ; Schwartz; William S.;
(Pleasant Ridge, MI) ; Rutkowski; Brian D.;
(Ypsilanti, MI) |
Correspondence
Address: |
Dickinson Wright PLLC
38525 Woodward Avenue, Suite 2000
Bloomfield Hills
MI
48304
US
|
Family ID: |
40953939 |
Appl. No.: |
12/032194 |
Filed: |
February 15, 2008 |
Current U.S.
Class: |
123/41.02 ;
180/165 |
Current CPC
Class: |
F01P 2037/02 20130101;
F02N 2200/023 20130101; F01P 2050/24 20130101; F01P 7/167 20130101;
F01P 7/164 20130101; F02N 11/0818 20130101 |
Class at
Publication: |
123/41.02 ;
180/165 |
International
Class: |
F01P 7/00 20060101
F01P007/00 |
Claims
1. An internal combustion engine, comprising: an engine housing
having a plurality of coolant passages; a heat exchanger for
rejecting heat from coolant circulated from said engine housing;
and a variable speed coolant pump for circulating coolant from said
engine housing to said heat exchanger, with said coolant pump
operating according to a predetermined, variable duty cycle at
lower coolant temperatures, and with the pump operating at a
selected one of a plurality of predetermined fixed speeds, as a
function of at least engine speed and engine load, once the engine
has attained a higher, stable operating temperature.
2. An internal combustion engine according to claim 1, wherein the
operating speed of said pump is additionally a function of engine
coolant temperature.
3. An internal combustion engine according to claim 1, wherein said
pump is operated at a predetermined fixed speed if heat is
requested from a passenger cabin heater furnished with coolant by
said pump.
4. An internal combustion engine according to claim 1, wherein said
pump is driven by a motor.
5. An internal combustion engine according to claim 4, wherein said
pump is driven by an electric motor.
6. An internal combustion engine according to claim 4, wherein said
pump is driven by a fluid motor.
7. An internal combustion engine according to claim 1, wherein said
pump is shut of when the engine is turned off, unless heat is
requested from a passenger cabin heater furnished with coolant by
said pump.
8. An internal combustion engine according to claim 1, wherein
operation of said pump at said variable duty cycle is at a fixed
speed.
9. An internal combustion engine according to claim 1, further
comprising a controller for operating said pump.
10. A method for operating a variable speed coolant pump for
circulating liquid coolant through a housing of an internal
combustion engine, as well as through a heat exchanger, comprising:
duty-cycle operation of the pump initially at a variable duty cycle
selected as a function of at least a temperature of the engine; and
select-speed operation of the pump at a selected one of a plurality
of predetermined fixed speeds, with said speed being selected as a
function of at least engine speed and engine load, once the engine
has attained a stable operating temperature.
11. A method according to claim 10, further comprising operating
the pump during final warmup at a single predetermined fixed speed
between said duty-cycle operation and said select-speed
operation.
12. A method according to claim 10, wherein said duty-cycle
operation comprises a first period of operation at a shorter duty
cycle, while the coolant temperature is below a first threshold,
and a second period of operation, at a longer duty cycle, while the
coolant is between said first threshold and a second, higher
threshold.
13. A method according to claim 12, wherein operation at said
longer duty cycle is followed by operation of the pump during a
third time period at a single predetermined fixed speed during
final warmup at temperatures between said second threshold and a
third threshold which is higher than the second threshold.
14. A method according to claim 13, wherein said select-speed
operation is initiated at coolant temperatures above said third
threshold.
15. A method according to claim 10, wherein said duty-cycle
operation comprises a first period of operation at a shorter duty
cycle in the range of 10%-20%, while the coolant temperature is
below a first threshold, and a second period of operation, at a
longer duty cycle, in the range of 40%-60%, while the coolant is
between said first threshold and a second, higher threshold.
16. A method according to claim 10, wherein said duty-cycle
operation comprises a first period of operation at a shorter duty
cycle, while the coolant temperature is below a first threshold,
and a second period of operation, at a longer duty cycle, while the
coolant is between said first threshold and a second, higher
threshold, with said duty-cycle operation occurring at a fixed pump
speed.
17. A hybrid vehicle, comprising: an internal combustion engine; an
energy storage device incorporated in a regenerative braking
system; and a cooling system for said engine, with said cooling
system comprising: an engine housing having a plurality of coolant
passages; a heat exchanger for rejecting heat from coolant
circulated from said engine housing; and a variable speed coolant
pump for circulating coolant from said engine housing to said heat
exchanger, with said coolant pump operating according to a
predetermined, variable duty cycle at lower coolant temperatures,
and with the pump operating at a selected one of a plurality of
predetermined fixed speeds, as a function of at least engine speed
and engine load, once the engine has attained a stable operating
temperature.
18. A hybrid vehicle according to claim 17, wherein said pump is
operated at a predetermined fixed speed if heat is requested from a
passenger cabin heater furnished with coolant by said pump.
19. A hybrid vehicle according to claim 17, further comprising a
controller, connected with said engine and said energy storage
device, for operating said pump, as a function of engine speed,
engine temperature, and engine load.
20. A hybrid vehicle according to claim 17, further comprising a
controller, connected with said engine and said energy storage
device, for operating said pump, as a function of engine speed,
engine temperature, and engine operating condition.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] None.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an internal combustion
engine having a coolant pump with a drive speed which is controlled
independently of the rotational speed of the engine.
[0004] 2. Disclosure Information
[0005] Hybrid vehicles have been the subject of ever-increasing
engineering activity prompted by the desire for increased vehicular
fuel economy. One of the principle mechanisms employed with hybrid
vehicles to greatly increase fuel economy is the stop-start mode of
operation in which the vehicle's engine is shut down when the
vehicle is stopped in traffic, such as at a traffic signal. Of
course, it is desirable to keep various vehicle systems in
operation notwithstanding the vehicle's engine has been shut down,
and for this reason many accessories such as a power steering pump
and an air conditioning compressor have been migrated from
traditional mechanical drives to electro drives. In the case of a
vehicle water pump, or coolant pump, there has been general
recognition of benefits obtained from removing the coolant
pump--often the last component powered by a front end accessory
drive of an engine--from the engine and replacing the mechanical
pump with an electric pump. Known electric pumps, however, are not
generally well-suited for use with passenger automotive vehicles
because such pumps operate in a manner which generally inhibits
warmup of the engine, while overcooling the engine in certain
operating modes, while at the same time consuming more power than
is necessary to achieve the required cooling.
[0006] It would be desirable to provide a motor-driven coolant pump
which promotes rapid, safe, and complete warmup of a vehicle
engine, while minimizing energy consumption when a normal, stable,
operating temperature has been reached, while at the same time
providing heated coolant to a cabin heater in the event that the
vehicle's engine has been turned off.
SUMMARY OF THE INVENTION
[0007] According to an aspect of the present invention, an internal
combustion engine includes an engine housing having a number of
coolant passages and a heat exchanger for rejecting heat from
coolant circulated from the engine housing. A variable speed
coolant pump circulates coolant from the engine housing to the heat
exchanger. The coolant pump operates according to a predetermined
variable duty cycle at lower coolant temperatures. The pump
operates at a selected one of a number of predetermined fixed
speeds, as a function of at least engine speed and engine load,
once the engine has attained a higher, stable operating
temperature. Once a stable operating temperature has been reached,
the pump's operating speed may additionally be a function of engine
coolant temperature. Operation of the pump at a variable duty cycle
may be accomplished at either a fixed or a variable speed, but
preferably occurs at a variable speed.
[0008] According to another aspect of the present invention, the
coolant pump is operated at a predetermined fixed speed if heat is
requested by a passenger cabin heater furnished with coolant by the
pump.
[0009] According to another aspect of the present invention, the
pump is preferably driven by a motor, such as an electric motor or
a fluid motor. Alternatively, the pump may be driven by a variable
speed drive connected with the engine's crankshaft or camshaft.
[0010] According to another aspect of the present invention, a
method for operating a variable speed coolant pump for circulating
liquid coolant through the housing of an internal combustion
engine, as well as through a heat exchanger, includes duty-cycle
operation of the pump initially at a variable duty-cycle selected
as a function of at least a temperature of the engine, and
select-speed operation of the pump at a selected one of several
predetermined fixed speeds, with the speed being selected as a
function of at least engine speed and engine load, once the engine
has attained a higher, stable operating temperature.
[0011] The present method further includes operating the pump
during final warmup at a single predetermined fixed speed between
the period of duty-cycle operation and the period of select-speed
operation.
[0012] According to another aspect of the present method, the
duty-cycle operation includes a first period of operation at a
shorter duty-cycle, while the coolant temperature is below a first
temperature threshold, and a second period of operation, at a
longer duty-cycle, while the coolant is between the first
temperature threshold and a second, higher temperature threshold.
Operation at the greater duty-cycle may be followed by operation of
the pump at a single predetermined fixed speed during final warmup
at temperatures between the second threshold and a third
temperature threshold which is higher than the second
threshold.
[0013] According to another aspect of the present invention, a
hybrid vehicle includes an internal combustion engine and an energy
storage device incorporated in a regenerative braking system. A
cooling system for the engine includes an engine housing having a
number of coolant passages, a heat exchanger for rejecting heat
from coolant circulated from the engine housing, and a variable
speed coolant pump for circulating coolant from the engine housing
to the heat exchanger, with the coolant pump operating according to
a predetermined variable duty-cycle at lower coolant temperatures,
and with the pump operating at a selected one of a number of
predetermined fixed speeds, as a function of at least engine speed
and engine load, once the engine has attained a stable operating
temperature.
[0014] It is an advantage of a system and method according to the
present invention that an internal combustion engine may be warmed
rapidly, so as to help minimize exhaust emissions and fuel
consumption, particularly by allowing a hybrid vehicle to
transition rapidly into a stop-start mode of operation.
[0015] It is another advantage of a method and system according to
the present invention that an engine equipped with the system may
be operated economically once it has reached a stable operating
temperature, because the coolant pump will extract no more work
than is necessary for the real-time operating conditions of the
engine.
[0016] Other advantages, as well as features of the present
invention will become apparent to the reader of this
specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic representation of a hybrid vehicle
having a cooling system according to the present invention.
[0018] FIG. 2 is a plot showing operation of a variable speed
coolant pump according to an aspect of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] As shown in FIG. 1, internal combustion engine 18 has an
engine housing, 42, with a number of coolant passages 44. A heat
exchanger, 46, rejects heat from coolant circulated from engine
housing 42. A variable speed coolant pump, 34, circulates coolant
from engine housing 42 to heat exchanger 46. Coolant pump 34 is
driven by a motor 38, which may be configured as either an electric
motor, or a fluid motor, or a mechanical or fluid drive associated
with a crankshaft or camshaft (neither is shown) of engine 18.
[0020] Pump 34 and motor 38 are controlled by controller 50, which
is operatively connected with not only motor 38 and pump 34, but
also with engine 18, and energy storage device 30.
[0021] Energy storage device 30 may be configured as either an
electrical traction battery, or a pumped storage device such as a
hydraulic or compressed gas energy storage device. Energy storage
device 30 is connected with pump motor 22, which may be configured
as either a fluid pump and motor, or as an electrical generator and
motor. Pump motor 22 either alone, or in combination with engine
18, powers final drive 26, which in turn powers a pair of road
wheels 14. When operated in a regenerative braking mode, final
drive 26 rotates pump/motor 22 so as to provide energy to storage
device 30. Depending upon whether vehicle 10 is a so-called hard or
soft hybrid, engine 18 may be rotated in unison with
generator/motor 22 or not. This detail is beyond the scope of the
present invention.
[0022] The main purpose of pump 34 is to circulate coolant from
engine 18 through heat exchanger 46 and, if called for, to cabin
heater 40, which has access to coolant controlled by means of
valves 41. Controller 50 operates pump 34 and motor 38 according to
the scheme shown generally in FIG. 2. Thus, when engine 18 is
started cold, controller 50 will operate motor 38 initially at a
variable duty-cycle selected as a function of at least a
temperature of engine 18. In a preferred embodiment, the
temperature of a cylinder head of engine 18 is used as a control
parameter. The first period of operation, shown as duty-cycle A of
FIG. 2, is a shorter duty-cycle employed when the coolant
temperature is below a first threshold shown at temperature T1.
This shorter duty-cycle, A, is used circulate coolant minimally
through passages 44, so as to avoid any significant cooling of the
engine, while preventing hot spots at locations adjacent the
combustion chambers of engine 18. Once temperature T1 has been
reached, controller 50 operates pump 34 and motor 38 according to
duty-cycle B, which is a longer duty-cycle characterized by
purposeful circulation of coolant within coolant passage 44 located
within engine housing 42. In essence, during operation of
duty-cycle B between temperatures T1 and T2, the engine coolant is
warmed uniformly.
[0023] Once engine operating temperature exceeds temperature T2,
the final warmup stage is entered. Thus, between temperatures T2
and T3 of FIG. 2, pump 34 is operated at a single, predetermined,
fixed speed which allows final warmup, without overcooling engine
18. The prevention of overcooling is important because stop-start
operation desirably occurs only when temperature T3 has been
attained, and it is desirable to obtain this level of control as
soon as possible during each operating episode of engine 18, so as
to allow engine 18 to be shut off if vehicle 10 is stopped, for
example, at a traffic signal.
[0024] Once temperature T3 has been attained, controller 50 will
operate pump 34 in select-speed operation mode. While in
select-speed operation, pump 34 is operated at a selected one of a
number of predetermined fixed speeds as a function of at least the
rotational speed of engine 18, and the load imposed on engine 18 by
the vehicle driver and by pump/motor 22. An operating temperature
of engine 18, such as cylinder head temperature may also be
employed in the selection of the pump speed at temperatures in
excess of T3. In any event, a purpose of the cooling system is to
maintain the temperature at a value less than T.sub.MAX.
[0025] According to another aspect of the present invention, a
method for operating variable speed coolant pump 34 includes
duty-cycle operation, such as at duty-cycles A and B, of FIG. 2,
initially, or in other words, at cold startup, with duty-cycles A
and B being selected as a function of at least a temperature of
engine 18, followed by select-speed operation of pump 34, with pump
speed being selected as a function of at least the rotational speed
of engine 18 and load imposed upon engine 18, provided engine 18
has attained a stable operating temperature. In one example, pump
38 was operated at a duty-cycle A of about 20%, from a cold
start-up of approximately 70.degree. F. until a cylinder head
temperature of about 180.degree. F. (T1) was reached. Then,
operation continued at a duty-cycle B of about 50% until a cylinder
head temperature of about 188.degree. F. (T2) was attained. This
was followed by a period of final warmup operation at a fixed speed
of about 1300 RPM until a temperature of about 190.degree. F. (T3)
was realized. Then, select speed operation ensued at pump speeds
ranging from about twice engine speed at idle to pump speeds
approximating engine speed at high loads and the highest engine
speeds. While operating in the select speed mode, the pump speed
will be chosen as a function of the engine's operating condition,
including at least engine load, as determined by engine and vehicle
operating parameters such as throttle position.
[0026] Controller 50 has the capability to further control engine
18 by shutting engine 18 off for brief periods once temperature T3
has been attained and vehicle 10 has been brought to an idle
condition, such as at a traffic signal. In the event that cabin
heater 40 is in a demand mode, valves 41 and pump 34 may be
operated by controller 50 so as to circulate engine coolant through
heater 40 without causing the coolant to be circulated through heat
exchanger 46. In this manner, the passenger cabin of vehicle 10 may
be provided with heat even when engine 18 is not running, without
rejecting heat to the atmosphere. Alternatively, heat exchanger 46
may be included in the coolant flow path, so as to provide
additional cooling capacity for engine 44
[0027] Although the present invention has been described in
connection with particular embodiments thereof, it is to be
understood that various modifications, alterations, and adaptations
may be made by those skilled in the art without departing from the
spirit and scope of the invention set forth in the following
claims.
* * * * *