Information
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Patent Grant
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6176205
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Patent Number
6,176,205
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Date Filed
Thursday, April 1, 199925 years ago
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Date Issued
Tuesday, January 23, 200123 years ago
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Inventors
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Original Assignees
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Examiners
- Wolfe; Willis R.
- Harris; Katrina B.
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CPC
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US Classifications
Field of Search
US
- 123 415
- 123 4114
- 123 4127
- 123 4152
- 123 4153
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International Classifications
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Abstract
The present invention provides an airtight reservoir in fluid communication with a cooling system of an internal combustion engine. This cooling system allows coolant to flow into the overflow bottle, thereby compressing air therein, and causing increases pressure. When the coolant again cools, the pressurized coolant flows back into the cooling system, thereby maintaining the system pressure above ambient.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
I. Technical Field
The present invention relates to an engine cooling system, and more particularly to an engine cooling system having an overflow bottle which maintains the cooling system in a pressurized state.
II. Discussion
Engine cooling systems play a critical role in internal combustion engine performance and operation. Primarily, the engine cooling system is responsible for maintaining the engine below a specific temperature by pumping heat, generated by the combustion of fuel within the engine, out to a radiator and ultimately to the atmosphere.
Typical automobile engine cooling systems are known as closed cooling systems. Closed cooling systems circulate a cooling medium, such as an antifreeze-water mixture, through a fully encapsulating circulatory system. This system has the advantage of using the increased temperature within the cooling system to correspondingly increase the pressure. Increased pressure increases the boiling point of the coolant which, as is understood by one skilled in the art, thereby increases the effectiveness of the system in dissipating heat. However, if the temperature of the engine and corresponding cooling medium becomes too high, the pressure within the cooling system will exceed design characteristics and cause damage to the system unless the system is fitted with some means for relieving this pressure. To reduce this pressure buildup, typical cooling systems are fitted with a pressure relieving cap and a reservoir. This cap, typically on the radiator, has a valve which allows pressurized coolant to flow into the tank when the pressure exceeds a specified limit. These check valves typically allow the pressure within the system to build to 14-18 psi before allowing coolant to flow into the tank.
When the engine and corresponding cooling system cools, the pressure within the system drops while the excess coolant remains in the reservoir. When the pressure of the system drops below atmospheric pressure, the difference in pressure between the system and the atmosphere causes coolant within the reservoir to flow back into the cooling system until the pressure equalizes. As a result, anytime the engine and corresponding cooling system is decreasing in temperature, the pressure of the system is usually at or below atmospheric pressure. Low pressure corresponds to a low boiling point temperature which, as discussed above, results in the system having a reduced effectiveness in dissipating heat.
To overcome this drawback, pressurized reservoirs which are maintained at the same pressure as the cooling system and through which a portion of the engine coolant circulates have been developed. These tanks allow the coolant space to expand and contract while maintaining the cooling system at a higher than atmospheric pressure. However, these reservoirs have several drawbacks. First, because of their complexity, typical pressurized reservoirs are rather large, thereby requiring much room in the engine compartment of an automobile. With the ever increasing number of components within an engine compartment, it is difficult to find room for such a tank. Second, again because of their complexity, these reservoirs are expensive. This, too, is an undesirable feature. Third, these reservoirs require at least two additional plumbing circuits to supply coolant to and remove from the reservoir.
SUMMARY OF THE INVENTION
The present invention overcomes the aforementioned drawbacks, among others, by providing an airtight reservoir with an air space in fluid communication with a cooling system of an internal combustion engine. This cooling system allows coolant to flow into the reservoir, thereby compressing air and increasing pressure. When the coolant again cools, the pressurized coolant flows back into the cooling system, thereby maintaining the system pressure above ambient.
In another aspect of the present invention, the reservoir contains a membrane ensuring that coolant and air do not mix. Also, a meltable plug can be fitted within a passage, which allows fluid communication between the reservoir and the cooling system, to allow filling of the system while maintaining the reservoir in a dry condition.
Additional advantages and features of the present invention will be apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1
is a graphical depiction of the state of the engine coolant during operation of a vehicle using a reservoir according to the prior art;
FIG. 2
is a perspective view of an internal combustion engine and a cooling circuit having a pressurized reservoir according to the present invention;
FIG. 3
is a cross-sectional view of a pressurized reservoir according to the present invention;
FIG. 4
is a graphical depiction of the state of the engine coolant during operation of a vehicle using a pressurized reservoir according to the present invention; and
FIG. 5
is a cross-sectional view of a second embodiment of a pressurized reservoir according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Referring now to
FIG. 1
, the operation of a conventional cooling system according to the prior art is graphically depicted. Between time=0 minutes and time=10 minutes, a vehicle containing an internal combustion engine is undergoing a heavy load, such as that associated with traveling up the side of a mountain. During this time, the engine generates heat at a rate greater than the cooling system can expel. As a result, the temperature and pressure within the cooling system increases. Once the pressure reaches the cooling system cap relief pressure, a relief valve is opened and coolant flows into a reservoir at ambient pressure. Between 10 and 20 minutes, the vehicle undergoes a light load, such as that associated with traveling down the side of a mountain. In this situation, the cooling system expels more heat than the engine generates. As a result, the temperature and corresponding pressure, as shown, decreases. Because the coolant in the reservoir is at ambient pressure, it does not flow back into the cooling system until the system is at a pressure below ambient. The absence of the excess coolant in the system, combined with a drop in pressure, causes the pressure within the system to rapidly drop. Because of this low pressure, the boiling point of the coolant contained in the system falls to a level at or below its current temperature. This causes vaporization and reduces the cooling system's overall effectiveness.
Referring now to
FIG. 2
, a pressurized reservoir
10
according to the present invention is shown in conjunction with an engine cooling system
11
and internal combustion engine
13
. Engine cooling system
11
has a radiator
12
which is fluidly connected to internal combustion engine
13
by upper hose
14
and lower hose
24
. This fluid connection allows lower hose
24
to circulate coolant
15
through a cylinder block water jacket
20
and cylinder head water jacket
18
of internal combustion engine
13
. Water pump
28
facilitates this flow by drawing water from lower hose
24
and pushing it through cylinder block water jacket
20
and cylinder head water jacket
18
. Within cylinder block water jacket
20
and cylinder head water jacket
18
, heat is transferred to coolant
15
thereby cooling internal combustion engine
13
and heating coolant
15
. Heated coolant
15
travels out of internal combustion engine
13
and travels into upper hose
14
if thermostat
16
is open. If thermostat
16
is closed, coolant
15
is recirculated through cylinder block water jacket
20
and cylinder head water jacket
18
. Thermostat
16
opens at a predefined coolant temperature to allow coolant
15
to flow into upper hose
14
and into radiator
12
. Radiator
12
uses airflow between fluid passages thereof to cool the heated coolant
15
and provide cool coolant
15
back to lower hose
24
for recirculation.
Referring now to
FIGS. 2 and 3
, pressurized reservoir
10
fluidly communicates with upper hose
14
to allow heated and pressurized coolant
15
to flow therein. Pressurized reservoir
10
generally comprises a spherical wall portion
17
which encapsulates an air filled center. Wall portion
17
is airtight and is preferably made of plastic or other suitable material which is able to withstand temperatures in the range of 130 degrees C. Contained within pressurized reservoir
10
is air. This air remains at ambient pressure when no coolant
15
has entered said reservoir. This allows the tank to be constructed from an inexpensive material since the tank does not have to be maintained at high pressure all the time. Pressurized reservoir
10
fluidly communicates with upper hose
14
by tube
32
. Like wall portion
17
, tube
32
is airtight and allows coolant
15
from upper hose
14
to flow within wall portion
17
of pressurized reservoir
10
. Preferably, reservoir
10
is oriented such that it is above upper hose
14
such that the buoyancy of air and gravity tend to push coolant
15
back into upper hose
14
. This helps ensure that air and coolant do not mix. Preferably, tube
32
has a meltable plug
33
which, when coolant
15
achieves a predetermined temperature, melts. This allows the cooling system to be filled with coolant
15
while maintaining pressurized reservoir
10
dry for assembly purposes. Once the temperature of cooling system
11
achieves the predetermined temperature, meltable plug
33
melts, thereby allowing uninterrupted communication between the coolant flow circuit and the reservoir for normal operation of the system.
When the internal combustion engine
13
is first started, internal combustion engine
13
and coolant within engine cooling system
11
are at ambient temperature. Also, thermostat
16
is closed. As internal combustion engine
13
is run, its temperature and the corresponding temperature of coolant
15
within cooling system
11
increases. This causes thermostat
16
to open, allowing coolant from internal combustion engine
13
to circulate through radiator
12
and dissipate heat.
When internal combustion engine
13
undergoes extreme loads, such as that associated with mountain driving or hauling, heat is transferred to cooling system
11
faster than radiator
12
can dissipate it. This results in an overall increase in temperature of coolant within engine cooling system
11
. As is known, the increased temperature of the coolant
15
corresponds to an increased pressure in a closed system. Increased pressure results in an increased boiling point. An increased boiling point allows more heat to be transferred to coolant
15
before it boils. When the temperature of coolant within engine cooling system
11
reaches its boiling point temperature, coolant within engine cooling system
11
evaporates, creating a concentration of vapor within radiator
12
and engine
13
. Because vapor has poorer heat transfer characteristics than liquid, the effectiveness of radiator
12
for dissipating head is reduced when coolant
15
boils. Therefore, it is desirable to maintain the pressure within cooling system as high as possible to maintain an elevated boiling point of coolant
15
. However, the design characteristics of cooling system
11
allows coolant
15
to reach a finite pressure, typically 14-18 PSIG. Once coolant
15
exceeds this pressure, some coolant must be bled from the system, thereby expanding the volume and correspondingly dropping the pressure of coolant
15
. As such, pressurized reservoir
10
of the present invention provides for this expansion.
As coolant
15
increases in pressure, it flows into pressurized reservoir
10
from upper hose
14
. This expansion causes air within pressurized reservoir
10
to compress, thereby increasing its pressure and the pressure of the corresponding coolant
15
. Since the air initially within pressurized reservoir
10
was at ambient pressure, the increase in pressure is greater than ambient pressure. This, in turn, maintains the pressure within engine cooling system
11
at higher than ambient pressure.
When internal combustion engine
13
undergoes a light load, such as when traveling on the down side of a mountain, it transfers heat to coolant
15
at a rate lower than that which radiator
12
can dissipate. As a result, the overall temperature of coolant
15
is reduced, thereby reducing the overall pressure within engine cooling system
11
. Since the previous flow of coolant into pressurized reservoir
10
created increased pressure therein, there exists a pressure differential between pressurized reservoir
10
and cooling system
11
. This pressure differential forces coolant
15
back into upper hose
14
and back into engine cooling system
11
, thereby maintaining pressure within cooling system
11
at a level either as high as or higher than ambient pressure.
Referring now to
FIG. 4
, the operation of the present invention is graphically depicted. Between time=0 and time=10 minutes, a vehicle containing internal combustion engine
13
undergoes a heavy load, such as that associated with traveling up the side of a mountain. As depicted in
FIG. 4
, the temperature and corresponding pressure increases during this time frame due to this load. This causes coolant
15
to expand into pressurized reservoir
10
, thereby increasing pressure therein and within engine cooling system
11
. Between time=10 minutes and time=20 minutes, the vehicle containing internal combustion engine
13
undergoes a light load, such as that associated with traveling down the side of a mountain. During this time, the temperature of coolant
15
within engine cooling system
11
decreases (as discussed above), thereby allowing coolant within pressurized reservoir
10
to flow back into cooling system
11
and maintain the corresponding pressure above atmospheric pressure.
Referring now to
FIG. 5
, a second embodiment of the present invention is described. In
FIG. 5
, pressurized reservoir
10
is shown having membrane
30
disposed therein which ensures that air within pressurized reservoir
10
and coolant
15
flowing therein are separated. Pressurized reservoir
10
is also fitted with a valve cock
132
which, when opened, allows coolant
15
to flow into pressurized reservoir
10
. Like meltable plug
33
, valve cock
132
allows the cooling system to be filled while maintaining the reservoir in a dry state.
While the above detailed description describes the preferred embodiment of the invention, it should be understood that the present invention is susceptible to modification, variation, and alteration without deviating from the scope and fair meaning of the following claims.
Claims
- 1. A reservoir for a cooling system for an internal combustion engine, said reservoir comprising:a receptacle for receiving coolant, said receptacle being substantially airtight, said receptacle having an external passageway for conducting coolant into and out of said receptacle, said external passageway attachable to a portion of said cooling system to allow airtight transfer of coolant into and out of said receptacle; and a melt plug located in said external passageway, said melt plug preventing said transfer of coolant into and out of said reservoir.
- 2. A reservoir as claimed in claim 1, wherein said melt plug liquefies at a predetermined temperature.
- 3. A reservoir as claimed in claim 2, wherein said melt plug liquefies at a temperature above 70 degrees C.
- 4. A reservoir for a cooling system for an internal combustion engine, said reservoir comprising:a receptacle for receiving coolant, said receptacle being substantially airtight, said receptacle having an external passageway for conducting coolant into and out of said receptacle, said external passageway attachable to a portion of said cooling system to allow airtight transfer of coolant into and out of said receptacle; and a manually operated valve located in said external passageway, said manually operated valve selectively actuable to allow and disallow said transfer of coolant into and out of said reservoir.
US Referenced Citations (19)
Foreign Referenced Citations (1)
Number |
Date |
Country |
247723 |
Nov 1969 |
RU |