Measuring and testing – Simulating operating condition – Marine
Reexamination Certificate
2003-03-18
2004-10-19
McCall, Eric S. (Department: 2855)
Measuring and testing
Simulating operating condition
Marine
Reexamination Certificate
active
06804996
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of the cyclic, torture testing of an engine cylinder head gasket. More particularly, the present invention relates to an apparatus and a method for rapidly cooling the engine, including the cylinder head and cylinders using the engine's liquid cooling system, from a high temperature of approximately about 230° F. to 250° F. to a temperature of approximately about −16° F. to −40° F., thereby stressing the head gasket to between its extreme sealing limits.
BACKGROUND OF THE INVENTION
Engine cylinder head gasket designs must be tested under extreme conditions to predict whether a particular design will be able to withstand a lifetime of rigors associated with the conditions to which it will be exposed in an engine during regular use. Tests are known for conducting torture tests of cylinder head gaskets for liquid cooled engines. In one type of test, the engine coolant in the engine is cycled between hot and cold under specific conditions for periods of time to cause the engine to expand and contract in a predetermined manner.
In this type of testing apparatus and method, the integrity of the engine's head gasket and design are tested by cyclically exposing the engine to extreme coolant temperatures by running the engine hard to make it become very hot and then by running super chilled coolant in the engine's cooling system, both for prolonged periods of time, thereby causing maximum expansion and contraction of the cylinder head, engine block, cylinder bolts, etc. and subsequent compression and relaxation of the head gasket. More specifically, the cylinder heads and cylinders are exposed to relatively high coolant temperatures of approximately about 230° F. to 240° F. and then relatively very cold or super chilled engine coolant is run into the testing system and engine so the engine is rapidly exposed to the very cold temperatures of about −40° F. to −16° F.
In fact, there is a known specification setting the parameters under which one OEM conducts such head gasket tests for engines. Ford Motor Company test specification CETP: 03.01-L315, details the timing, testing points, temperatures and methods for its preferred methodology in conducting head gasket torture testing, which is incorporated herein by reference. However, it is understood in practice that it is very difficult to develop a test apparatus which is capable of meeting every detail of this specification.
In one common test conducted pursuant to the Ford specification, the engine is exposed to the relatively hot engine coolant during a first test period and is then subsequently exposed to the relatively cold coolant in a second test period. During the first period, lasting on order about 15 minutes, the engine is started and stabilized at idle for 1 minute and as the first period continues the engine is then run at wide open throttle (W.O.T.) while yielding maximum horse power, and maximum internal cylinder pressures to stress the head gasket, for 14 minutes. During this first period the coolant out temperature commonly stabilizes between 230° F. to 240° F. and the coolant system pressure is on the order of approximately between 13 and 16 psig (90 to 110 kPa).
At the end of the first period, the engine is stopped (i.e., zero RPM) during the second test period for approximately 15 minutes. During the second test period, the relatively hot coolant is continuously replaced with super chilled coolant to maintain the coolant out temperature from the engine between approximately about −16° F. to −40° F. as quickly as possible, preferably within ten minutes of engine stoppage and remain at that level until fifteen minutes has passed since the engine stopped. The completion of the first and second test periods, completes one thirty minute test cycle. The test cycle is then continuously repeated until the engine cylinder gasket experiences a predetermined number of testing cycles (typically at least 50 or more testing cycles depending on the type of engine and customer requirements) or until the head gasket fails.
A conventional testing apparatus design for conducting a head gasket test for cooling the engine coolant to perform the second period of the testing cycle is shown in FIG.
1
. Depending upon the engine size and type, a typical chill cycle (or second test period) requires 5 to 25 gallons per minute of super chilled coolant to reach the desired engine out cold temperature of approximately −16° F. to −40° F. Thus, for a 15 minute second test period, there will be required approximately between 75 and 375 gallons of super chilled engine coolant to complete one testing cycle. Since it is common for one cooling system to be designed to support several simultaneously running engine head gasket tests, the amount of required super chilled engine coolant may be doubled, tripled or even more. Thus, existing test facilities are known to begin with a 2000-3000 gallon insulated cold storage tank
20
containing a coolant
21
typically maintained between approximately −20° F. and −40° F.
It should be noted that the engine coolant can be any conventional or appropriate coolant or other liquid (or a combination thereof) that has a freezing point less than approximately −50° F. Usually, it is common to use a 40/60 mixture of water and conventional coolant, such as an ethylene-glycol based coolant.
The tank
20
has an inlet
24
, an outlet
26
, and a vent
22
. Super chilled coolant
21
exits the cold storage tank
20
, via the outlet
26
, and is pumped by a first vane or rotary pump
28
to a first valve
30
. The coolant
21
entering the first valve
30
flows, via an inlet
32
, into the cooling system of the engine
34
around the cylinder and cylinder head cooling cavities. While in the engine
34
, the coolant
21
absorbs heat from the engine
34
thereby reducing the temperature of the engine
34
and its components. After passing through the engine
34
, the coolant
21
exits, via an outlet
36
, and flows to a second valve
38
. At this juncture, the coolant
21
may be channeled into a air-cooled radiator
42
(via a radiator inlet
40
) or be channeled into a recovery tank
48
. It should be appreciated that the tank
48
must necessarily be of equal or greater size than storage tank
20
.
Referring still to
FIG. 1
, if the coolant
21
is directed to the radiator
42
, the coolant passes there through and exits the radiator
42
via an outlet
44
. The coolant
21
then flows back to the first valve
30
which, in turn, directs the coolant
21
back to the engine
34
. This is the typical valve selection and coolant flow for the hot cycle or the first test period wherein the coolant in the engine runs at a temperature of approximately about 230° F. to 240° F. On the other hand, if the coolant
21
exiting the engine
34
at the outlet
36
is pumped into an inlet
46
of the recovery tank
48
, two possible results exist for the coolant
21
.
The first result is that the heated engine coolant
21
may be channeled, via an outlet
36
in the recovery tank
48
, into a refrigeration or super chilling unit
66
via an inlet
64
in the refrigeration unit
66
. The refrigeration unit
66
is typically a relatively very large capacity system in the 30-100 ton range (wherein the system is capable of removing heat from the engine coolant at a rate of 360,000 to 1,200,000 BTU/Hr or 6,000 to 20,000 BTU/Min). The refrigeration unit
66
must be sufficiently large enough to rapidly cool the engine coolant
21
in the recovery tank
48
to the desired testing temperature while minimizing down time between cycles. The refrigeration unit
66
employs conventional mechanical cooling techniques such as using a hydrofluorocarbon refrigerant, or the like, to create a sufficient cooling capacity to super chill the engine coolant
21
to approximately −20° F. to −40°F. (“testing temperature”) for use in conducting the head gasket test. Despite the significantly large cooling ca
EDP Technical Services, Inc.
Foley & Lardner LLP
McCall Eric S.
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