Internal-combustion engines – Cooling – With jacketed head and/or cylinder
Reexamination Certificate
2002-11-27
2004-12-14
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Cooling
With jacketed head and/or cylinder
Reexamination Certificate
active
06830016
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system and method for cooling an engine, and more particularly, to a system and method for cooling an engine by separately cooling an engine's cylinder block and cylinder head.
BACKGROUND OF THE INVENTION
An internal combustion engine produces power by burning fuel in air. Accordingly, such engines are typically provided with cooling systems to radiate heat produced during the combustion away from the engine. Two types of cooling systems are widely used, namely, water-cooled systems and an air-cooled systems. Air-cooled systems cool the engine by flow of air, while water-cooled systems cool the engine by forcing coolant through the engine.
FIG. 1
shows a typical construction of a water-cooled system.
An engine
100
includes a cylinder head
110
and a cylinder block
120
, where the cylinder head
110
and the cylinder block
120
respectively have first and second water-jackets
115
and
125
. The first and second water-jackets
115
and
125
are connected and open to each other such that cylinders (not shown) and combustion chambers (not shown) are enclosed by the first and second water jackets
115
and
125
. The first and second water-jackets
115
and
125
are usually collectively called the water-jacket.
A water-cooled cooling system includes a radiator
150
for cooling the coolant. Hot coolant is supplied from the water-jackets
115
and
125
to the radiator
150
through a high-temperature coolant line
130
. The coolant, once cooled at the radiator
150
, returns to the engine
100
through a low-temperature coolant line
140
. A hydraulic pump
160
for generating such coolant flow is provided at a portion of the engine
100
.
When the engine
100
is initially started, the coolant does not have to be cooled because its temperature is low. In fact, the coolant flow is generally blocked to quickly increase the coolant temperature. For this reason, a thermostat
170
is provided at a predetermined position in one of the high-temperature coolant line
130
and the low-temperature coolant line
140
. The thermostat
170
opens the coolant line when the coolant temperature is above a predetermined temperature, and closes the coolant line when the coolant temperature is below the predetermined temperature. As shown in
FIG. 1
, the thermostat
170
can be disposed along either the high-temperature coolant line
130
or the low-temperature coolant line
140
, at either end of the engine, such as at point A or B.
Furthermore, such a coolant circulation system typically includes a heater
180
for radiating heat into the interior of a vehicle. This heater
180
radiates heat of the coolant, supplied through the high-temperature coolant line
130
, into the interior of the vehicle. In order to quickly radiate heat, a heater supply-line
185
, for supplying coolant to the heater
180
, is connected to the high-temperature coolant line
130
or to the cylinder head
110
(as shown). Where the thermostat
170
is disposed at the high-temperature coolant line
130
, the heater supply-line
185
is connected to either the cylinder head
110
, or between the engine and the thermostat
170
. Where the thermostat
170
is disposed at the low-temperature coolant line
140
, the heater supply-line
175
may be connected elsewhere.
Coolant is also supplied to a throttle body
190
that includes a throttle valve. The connection of a throttle body supply-line
195
for supplying coolant to the throttle body
190
is similar to the connection of the heater supply-line
185
described above.
In use, when the engine
100
is cool, the thermostat
170
closes the low-temperature coolant line
140
such that coolant flow to the radiator
150
is blocked. Accordingly the coolant circulates in the first and second water-jackets
115
and
125
, the heater
180
, and the throttle body
190
as shown by dotted arrows in FIG.
1
. Once the engine
100
has warmed up such that the coolant temperature becomes a predetermined temperature (usually preset in the range of 82° C. and 88° C.), the thermostat
170
is opened such that the coolant can circulate through the radiator
150
as shown by solid arrows in FIG.
1
. Because the cylinder head
110
is exposed to more heat than any other part in the internal combustion engine, more heat is conducted and radiated through the cylinder head
110
. While the engine is warming up, coolant flows through the heater
180
and the throttle body
190
. However, such coolant flows through the cylinder block
120
, as well as the cylinder head
110
, and accordingly heating efficiency to the interior of a vehicle is deteriorated. Furthermore, the warm-up period is lengthened.
In addition, during the warm-up period where the engine
100
is below a normal operating temperature, a catalytic converter, used for emission-control, does not sufficiently function to reduce noxious gas. Therefore, if the warm-up period is reduced, noxious exhaust gas may be reduced.
Furthermore, fuel consumption is increased during the warm-up period because lubricant temperature is low and its viscosity is high such that friction of mechanical parts of the engine
100
is high. Therefore, if the warm-up period is reduced, fuel consumption may also be lowered.
What is more, when the engine is warmed up to a normal operating temperature, the cylinder head
110
is exposed to substantially large amounts of heat. Therefore, heat from the cylinder head
110
should be more efficiently radiated. Furthermore, a cooling system and method of an engine should be preferably enhanced to reflect engine load, as radiation of heat is dependent on whether the engine load is high or low.
SUMMARY OF THE INVENTION
Embodiments of the present invention provide systems and methods for cooling an engine where a cylinder block and cylinder head are separately cooled. It should be appreciated that a “thermostat” as used here includes any device that acts as a valve, which is open at a temperature above a predetermined temperature, and closed at a temperature below the predetermined temperature. Also, a “water-jacket” as used herein includes any kind of passage with any shape, for enabling flow of coolant.
The cooling systems described herein are preferably used for cooling an engine. The engine preferably includes a cylinder head and a cylinder block. The cylinder head includes a head water-jacket for circulating coolant, while the cylinder block includes a block water-jacket for circulating the coolant. An exemplary cooling system also preferably includes a radiator for cooling the coolant, a high-temperature coolant line for supplying the coolant from the cylinder head to the radiator, a low-temperature coolant line for supplying the coolant from the radiator to at least one of the head and block water-jackets, a first thermostat disposed at a predetermined position in either the low-temperature coolant line or the high-temperature coolant line, a branch coolant line for supplying the coolant from the block water-jacket to the high-temperature coolant line, a second thermostat disposed at the branch coolant line, and a hydraulic pump for generating coolant flow in the coolant lines. The head and block water-jackets communicate with each other via a primary pathway for transporting the coolant therebetween. Also, coolant flow is blocked within a cylinder-region, where the cylinder region is a region between the primary pathway and the branch coolant line.
The low-temperature coolant line preferably supplies the coolant to the block water-jacket. A bypass flow-line for bypassing the second thermostat is preferably formed at the branch coolant line and/or the second thermostat.
A flow-rate of the second thermostat is preferably smaller than a flow-rate of the first thermostat by a predetermined ratio. More specifically, the predetermined ratio is preferably preset such that the ratio of coolant flow passing through the head water-jacket and the block water-jacket lies within a range of 7:3 to 5:5.
The primary pathway is preferably formed near
Ali Hyder
Argenbright Tony M.
Hyundai Motor Company
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