U.S. patent application number 10/310781 was filed with the patent office on 2004-06-10 for engine cooling system thermostat bypass for dual temperature control.
This patent application is currently assigned to Daimler Chrysler Corporation. Invention is credited to Roth, David.
Application Number | 20040107922 10/310781 |
Document ID | / |
Family ID | 32468111 |
Filed Date | 2004-06-10 |
United States Patent
Application |
20040107922 |
Kind Code |
A1 |
Roth, David |
June 10, 2004 |
Engine cooling system thermostat bypass for dual temperature
control
Abstract
A dual temperature control system as part of an engine cooling
system. In one aspect, a valve is regulated as a function of engine
load and disposed in a by-pass line between the radiator and the
coolant pump. The valve is designed to normally block the by-pass
line, but permits coolant to by-pass the thermostat and be conveyed
from the radiator to the engine when the load of the engine
approaches a wide-open-throttle condition. In another aspect, both
high-temperature and low-temperature thermostats are employed and a
normally closed valve is actuated when the load of the engine
approaches a wide-open-throttle condition to permit coolant to be
conveyed through the low-temperature thermostat and on to the
engine.
Inventors: |
Roth, David; (West
Bloomfield, MI) |
Correspondence
Address: |
Ralph E. Smith
Daimler Chrysler Intellectual Capital Corporation
800 Chrysler Drive East
Auburn Hill
MI
48326-2757
US
|
Assignee: |
Daimler Chrysler
Corporation
|
Family ID: |
32468111 |
Appl. No.: |
10/310781 |
Filed: |
December 6, 2002 |
Current U.S.
Class: |
123/41.1 |
Current CPC
Class: |
F01P 2025/50 20130101;
F01P 2007/146 20130101; F01P 7/167 20130101 |
Class at
Publication: |
123/041.1 |
International
Class: |
F01P 007/14 |
Claims
What is claimed is:
1. An apparatus for regulating a coolant circuit for an engine, the
coolant circuit having a radiator, a thermostat, a coolant pump,
and a first coolant circuit for coolant flowing through the
radiator, thermostat, coolant pump, and engine, the radiator and
engine having feed and discharge lines, the apparatus comprising: a
second coolant circuit connecting the radiator discharge line to
the engine feed line; and a valve regulated as a function of engine
load and disposed in the second coolant circuit, the valve blocking
the second coolant circuit under normal operation of the engine and
permitting coolant to by-pass the thermostat and be conveyed from
the radiator discharge line to the engine feed line when the engine
load approaches a wide-open-throttle condition.
2. The apparatus of claim 1, wherein the coolant pump has a feed
and discharge line and is located upstream of the engine; and the
second coolant circuit is connected from the radiator discharge
line to the coolant pump feed line.
3. The apparatus of claim 1, wherein the valve comprises an
electronic actuation mechanism.
4. The apparatus of claim 1, wherein the valve comprises a
vacuum-actuation mechanism.
5. The apparatus of claim 4, wherein the engine comprises an intake
manifold plenum and further comprises a vacuum line, wherein the
vacuum line is disposed between the intake manifold plenum and the
vacuum-actuation mechanism.
6. The apparatus of claim 4, further comprising a vacuum switching
valve, wherein the vacuum switching valve is in fluid communication
with the vacuum-actuation mechanism.
7. An internal combustion engine, the engine having feed and
discharge lines, comprising: a radiator for cooling the internal
combustion engine, the radiator having feed and discharge lines; a
coolant pump for pumping coolant; a thermostat for regulating the
temperature of the coolant directed to the engine; a first coolant
circuit for the coolant flowing through the radiator, the
thermostat, the coolant pump, and the engine; a second coolant
circuit connecting the radiator discharge line to the engine feed
line; and a valve regulated as a function of engine load and
disposed in the second coolant circuit, the valve blocking the
second coolant circuit under normal operation of the engine and
permitting coolant to by-pass the thermostat and be conveyed from
the radiator discharge line to the engine feed line when the load
of the engine approaches a wide-open-throttle condition.
8. The engine of claim 7, wherein the coolant pump has a feed and
discharge line and is located upstream of the engine; and the
second coolant circuit is connected from the radiator discharge
line to the coolant pump feed line.
9. A method of regulating the temperature of an engine, comprising:
circulating coolant between a radiator and the engine, regulating
the temperature of the engine using a thermostat, by-passing the
thermostat and delivering coolant to the engine when the engine
load approaches a wide-open-throttle condition.
10. The method of claim 9, wherein the delivery further comprises
conveying coolant from the radiator to a coolant pump that
transfers coolant to the engine.
11. An apparatus for regulating a coolant circuit for an engine,
the coolant circuit having a radiator, a first thermostat, a
coolant pump, and a first coolant circuit for coolant flowing
through the radiator, first thermostat, coolant pump, and engine,
the radiator and engine having feed and discharge lines, the
apparatus comprising: a second thermostat; a second coolant circuit
connecting the radiator discharge line to the second thermostat to
the engine feed line; and a valve regulated as a function of engine
load and disposed in the second coolant circuit, the valve blocking
the second coolant circuit under normal operation of the engine and
permitting coolant to be conveyed from the radiator discharge line
to the second thermostat and to the engine feed line when the load
of the engine approaches a wide-open-throttle condition.
12. The apparatus of claim 11, wherein the coolant pump has a feed
and discharge line and is located upstream of the engine; and the
second coolant circuit is connected from the radiator discharge
line to the coolant pump feed line.
13. An internal combustion engine, the engine having feed and
discharge lines, comprising: a radiator for cooling the internal
combustion engine, the radiator having feed and discharge lines; a
coolant pump for pumping coolant; a first thermostat for regulating
the temperature of the coolant directed to the engine; a first
coolant circuit for the coolant flowing through the radiator, the
first thermostat, the coolant pump, and the engine; a second
thermostat for regulating the temperature of the coolant directed
to the engine; a second coolant circuit connecting the radiator
discharge line to the second thermostat to the engine feed line;
and a valve regulated as a function of engine load and disposed in
the second coolant circuit, the valve blocking the second coolant
circuit under normal operation of the engine and permitting coolant
to be conveyed from the radiator discharge line to the second
thermostat and to the engine feed line when the load of the engine
approaches a wide-open-throttle condition.
14. The engine of claim 13, wherein the coolant pump has a feed and
discharge line and is located upstream of the engine; and the
second coolant circuit is connected from the radiator discharge
line to the coolant pump feed line.
15. A method of regulating the temperature of an engine,
comprising: circulating coolant between a radiator and the engine,
regulating the temperature of the engine using a first thermostat,
and regulating the temperature of the engine using a second
thermostat when the load of the engine approaches a
wide-open-throttle condition.
16. The method of claim 15, wherein the second thermostat has a
setting of less than 190.degree. F.
17. The method of claim 15, wherein the regulating using a second
thermostat further comprises delivering lower temperature coolant
to the engine.
18. The method of claim 15, wherein the regulating using a second
thermostat further comprises conveying coolant to a coolant pump
that transfers coolant to the engine.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The invention relates to internal combustion engine cooling
systems, and more particularly to dual temperature control
arrangements for an engine cooling system.
[0002] In a typical liquid-cooled engine, the set-point of the
coolant thermostat is the result of a compromise between lowered
hydrocarbon emissions and improved fuel economy at part-load
conditions that favor a higher temperature set point, and the best
power available at Wide-Open-Throttle (hereinafter, "WOT") that is
benefited by a lower temperature set point. Currently, standard
practice is to set the thermostat at a temperature between
190.degree. F. and 200.degree. F. Specifically, part-load fuel
consumption and emissions are improved by operating the engine at
225.degree. F. to 240.degree. F., and peak power output can be
enhanced by operating at tempertures as low as 160.degree. F.
[0003] Higher coolant temperatures provide lower hydrocarbon
emissions input because warmer combustion chamber surface and
cylinder bore walls have thinner quench layers and therefore lower
hydrocarbon production. This lower hydrocarbon production, along
with friction reduction and lower throttle losses leads to better
fuel consumption. WOT performance is enhanced at lower coolant
temperatures because knock resistance is improved at lower
combustion chamber, inlet port, and piston surface temperatures.
Also, lower temperature intake ports can improve volumetric
efficiency. Additionally, higher than normal coolant temperatures
(above 210.degree. F.) at WOT are not practical due to the
associated reduction in knock resistance and hence power
output.
[0004] Behr Thermot-tronik Co.'s "MAP Controlled Cooling System"
accomplishes a dual thermostat setting by starting with a
high-temperature (roughly 230.degree. F.) thermostat that has a
electric heating element in the wax "motor" of the thermostat. When
electric current is applied to the heating element, the
high-temperature thermostat is fooled into opening fully, thereby
effectively lowering the set-point to a temperature that is more
advantageous for best power. One disadvantage of this system is
that it is relatively slow to react to the applied current as it
takes roughly 4 seconds for the thermostat to fully open.
Therefore, this system is inferior because transient power is
reduced due to knock limitations and due to the significant
calibration attention required by this system.
[0005] The foregoing demonstrates that there is a need for dual
temperature control of an engine cooling system that optimizes
hydrocarbon emissions, fuel economy, and power while providing
quick response time such that transient power is sustained.
[0006] The invention satisfies the need and avoids the drawbacks of
the prior art by providing an apparatus, system and method that
efficiently provides dual temperature control of an engine cooling
system. The invention also provides quicker response and lower cost
compared to electronic thermostats. The invention further provides
reduced pressure drop compared to an electronically-controlled
thermostat, at high power settings, which may allow additional
benefits with regard to coolant pump sizing.
[0007] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 provides a schematic view of one embodiment of the
system employing a dual thermostat feature according to the
principles of the invention.
[0009] FIG. 2 provides a schematic view of another embodiment of
the system utilizing an additional coolant circuit according to the
principles of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0010] It is understood that the coolant circuits depicted in FIGS.
1 and 2 relate to only a portion of an internal combustion engine,
which is of known design and function, and therefore the details of
the operation are only briefly discussed. An internal combustion
engine having a cylinder block 10 and a cylinder head 20 is
connected to a coolant circuit. The coolant circuit has a coolant
pump 30 which may be driven by the engine crankshaft. Located after
cylinder head 20 in the coolant flow direction is a tee 40 that
permits coolant to flow through a bypass line 50 to a thermostat or
through a radiator inlet line 60 to a radiator 70.
[0011] As is shown in FIG. 1, in one embodiment according to the
invention, radiator outlet line 80 permits coolant to flow from
radiator 70 to a tee 90 which splits into a high-temperature
thermostat inlet line 100 and a low-temperature thermostat line
110. High-temperature thermostat inlet line 100 permits coolant to
flow to a high-temperature thermostat 120 and low-temperature
thermostat line 110 permits coolant to flow to low-temperature
thermostat 130 when valve 140 is in an open position. From
high-temperature thermostat 120 and low-temperature thermostat 130
coolant flows through coolant pump inlet line 150 to coolant pump
30. Also bypass line 50 may be routed to flow over the
temperature-sensing element of thermostat 120 and/or 130 if this is
required to improve temperature regulation.
[0012] FIG. 2 illustrates a different embodiment, according to the
invention, where coolant flowing through the radiator outlet line
80 flows from radiator 70 to a tee 90 which splits into a
thermostat inlet line 200 and a by-pass inlet line 260. Coolant
flows from thermostat inlet line 200 to thermostat 220 and to
coolant pump 30 via coolant pump inlet line 250. Additionally,
according to the principles of the invention, when valve 270 is
open coolant flows from by-pass inlet line 260 to by-pass outlet
line 280 and then to coolant pump 30 via coolant pump inlet line
250 and on to cylinder block 10 and cylinder head 20. Of course,
the depicted arrangement of these devices and lines are
illustrative and could be modified according to the principles of
the invention. For example, the coolant pump may be located between
the cylinder block/head and the radiator. The thermostats of the
invention are depicted in a location at the pump inlet; however,
the thermostats may be located at the engine outlet. Also bypass
line 50 may be routed to flow over the temperature-sensing element
of thermostat 220 if this is required to improve temperature
regulation. A temperature monitor 160 is located between coolant
pump 30 and cylinder block 10, but, of course, could be located in
a variety of positions in the coolant circuit.
[0013] In one aspect, operation of the system accomplishes a dual
temperature advantage, according to the principles of the
invention, by employing valve 140 to direct coolant to the
low-temperature thermostat 130 and on to the cylinder block 10 and
cylinder head 20 to quickly cool the engine so as to improve peak
power output. In a preferred embodiment, when the system is
operating at part-throttle, valve 140 is closed and the temperature
of the coolant is controlled by high-temperature thermostat 120.
Valve 140 may be simple or complex and may be actuated using any
number of mechanisms including electric, mechanical and vacuum. The
lines used in the invention, such as line 110, may be hoses or any
other fluid conveying devices and may be constructed of any
suitable material acceptable for the temperatures, pressures, and
service associated with coolant systems for engines. According to
the principles of the invention, in order to take full advantage of
the inventive system, high-temperature thermostat 120 may be
designed to operate at a temperature that is significantly higher
than is what is employed in current practice. For example, current
systems that are controlled in a range of 195 to 200.degree. F. may
be modified to utilize thermostats having temperature set points in
a range of 220 to 240.degree. F. These higher temperatures are
advantageous for reduced hydrocarbon emissions and enhanced fuel
economy. During operation of the internal combustion engine
associated with the coolant system of the invention, when power
demand approaches or is at WOT, valve 140 will open to allow the
coldest coolant in the system, coolant exiting radiator 70, to flow
to low-temperature thermostat 130 and on to coolant pump 30, and at
an increased flow rate due to reduced pressure drop, to rapidly
lower the engine operating temperature. The lower engine operating
temperature results in an improved peak power output at WOT.
[0014] In another aspect of the invention, described in connection
with FIG. 2, operation of the system accomplishes a dual
temperature advantage by providing a by-pass circuit around a
themostat 220, as depicted in FIG. 2, via valve 270 and by-pass
inlet line 260 to by-pass outlet line 280. Like valve 140, valve
270 may be simple or complex and may be actuated using any number
of mechanisms including electric, mechanical and vacuum. Similarly
as described above, lines 260 and 280 may be hoses or any other
fluid conveying devices and may be constructed of any suitable
material acceptable for the temperatures, pressures, and service
associated with coolant systems for engines. In one preferred
embodiment, when the system is operating at part-throttle, valve
270 is closed and the temperature of the coolant is controlled by
thermostat 220, which is, according to the principles of the
invention, set at a temperature that is significantly higher than
is what is employed in current practice. For example, current
systems that are controlled in a range of 195 to 200.degree. F. may
be modified to utilize thermostats having temperature set points in
a range of 220 to 240.degree. F. These higher temperatures are
advantageous for reduced hydrocarbon emissions and enhanced fuel
economy. During operation of an internal combustion engine
associated with the coolant system of the invention, when power
demand approaches or is at WOT, bypass valve 270 will open to allow
the coldest coolant in the system, coolant exiting radiator 70, to
flow into coolant pump 30 directly, and at an increased flow rate
due to reduced pressure drop, and thereby rapidly lower the engine
operating temperature. The lower engine operating temperature
results in a desired peak power output at WOT.
[0015] In other embodiments, high-temperature thermostat 120 and
thermostat 220 may have lower temperature set points than described
above because suitable results may be obtained when the
high-temperature thermostat 120 is set at a higher temperature than
the low-temperature thermostat 130 with respect to the two
thermostat system, and in the single thermostat system of the
invention thermostat 220 should be set to provide the best
part-throttle overall performance and reduction of emissions. For
example, the thermostat may be set in a relatively low temperature
range of 160 to 180.degree. F. in a racing cooling system.
[0016] Valves 140 and 270 may be actuated in any number of manners.
In one embodiment, the valve is a vacuum-actuated valve where low
vacuum opens the valve and high vacuum closes the valve. The vacuum
line may be connected from valve to the intake manifold plenum.
Because the intake manifold plenum has very low vacuum when the
operating engine is at or near WOT, its low vacuum opens valve 140
or 270. Such a construction is advantageous as no electronic
controls are required.
[0017] In another embodiment, valves 140 or 270 may actuated using
an electric solenoid valve. When the operating engine approaches or
is at WOT, the valve is opened by a direct signal from an engine
controller.
[0018] In still another embodiment, the disclosed valves may be
vacuum-actuated where the vacuum signal to the valve is controlled
by a vacuum switching valve (VSV) controlled by an engine
controller. This alternative offers greater control than the
vacuum-actuated valve described above, and may be more economical
than an electric solenoid valve.
[0019] Because the opening of the valve 140 or 270, lowers the
overall flow resistance of the cooling system by decreasing the
flow resistance around the thermostat, cooling of the engine is
improved by the resultant increase in cooling flow rate through the
engine. The disclosed design may allow for downsizing of the
coolant pump and associated equipment and operating savings.
EXAMPLE
[0020] A system according to the principles of the invention, and
particularly the system depicted in FIG. 2, was constructed and
tested on a 4.7 L V8 engine in a vehicle. The standard 195.degree.
F. thermostat was replaced with a 225.degree. F. thermostat, and a
vacuum-actuated coolant-control valve was attached between the
radiator outlet hose and a fitting between the thermostat and the
pump inlet in the front cover of the engine utilizing 5/8" hose
fittings. After the vehicle's engine was warmed up, a WOT condition
was initiated and the temperature of the coolant conveyed through
the by-pass circuit to the coolant pump was lowered by
approximately 10.degree. F. in 5 seconds, which is substantially
faster than current systems.
[0021] Although the invention has been described and illustrated in
detail, it is to be clearly understood that the same is by way of
illustration and example, and is not to be taken by way of
limitation. The spirit and scope of the present invention are to be
limited only by the terms of the appended claims.
* * * * *