Cooling system for automotive engine or the like

In order to attenuate the amount of liquid coolant which flows from the coolant jacket to the radiator of an evaporative cooled internal combustion engine, a vapor manifold is arranged to induce the coolant vapor to flow through a collector section thereof in a manner that the liquid droplets develop a velocity which tends to carry the same through a drain port formed at one end of the manifold. The vapor is caused to pass out through a vapor discharge port formed at an acute angle with respect to the direction in which the coolant flows through the collector section. This induces a flow pattern in the vapor flow which produces an angular acceleration which separates liquid coolant droplets from the vapor before the vapor passes out through the vapor discharge port.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to an evaporative type cooling 
system for an internal combustion engine wherein liquid coolant is 
permitted to boil and the vapor used as a vehicle for removing heat 
therefrom, and more specifically to a simple and compact vapor manifold 
for such a system which attenuates excessive transmission of liquid 
coolant along with the coolant vapor between the engine coolant jacket and 
the radiator or condensor in which the coolant is condensed back to its 
liquid form. 
2. Description of the Prior Art 
In currently used "water cooled" internal combustion engines (liquid) is 
forcefully circulated by a water pump, through a cooling circuit including 
the engine coolant jacket and an air-cooled radiator. This type of system 
encounters the drawback that a large volume of water is required to be 
circulated between the radiator and the coolant jacket in order to remove 
the required amount of heat. 
Further, due to the large mass of water inherently required, the warm-up 
characteristics of the engine are undesirably sluggish. For example, if 
the temperature difference between the inlet and discharge ports of the 
coolant jacket is 4 degrees, the amount of heat which 1 Kg of water may 
effectively remove from the engine under such conditions is 4 Kcal. 
Accordingly, in the case of an engine having an 1800 cc displacement (by 
way of example) is operated full throttle, the cooling system is required 
to remove approximately 4000 Kcal/h. In order to achieve this, a flow rate 
of 167 liter/min (viz., 4000-60.times.14) must be produced by the water 
pump. This of course undesirably consumes several horsepower. 
FIG. 2 shows an arrangement disclosed in Japanese Patent Application Second 
Provisional Publication Sho. No. 57-57608. This arrangement has attempted 
to vaporize a liquid coolant and use the gaseous form thereof as a vehicle 
for removing heat from the engine. In this system the radiator 1 and the 
coolant jacket 2 are in constant and free communication via conduits 3, 4 
whereby the coolant which condenses in the radiator 1 is returned to the 
coolant jacket 2 little by little under the influence of gravity. 
This arrangement while eliminating the power consuming coolant circulation 
pump which plagues the above mentioned arrangement, has suffered from the 
drawbacks that the radiator, depending on its position with respect to the 
engine proper, tends to be at least partially filled with liquid coolant. 
This greatly reduces the dry surface area via which the gaseous coolant 
(for example steam) can effectively release its latent heat of 
vaporization and accordingly condense, and thus has lacked any notable 
improvement in cooling efficiency. Further, with this system in order to 
maintain the pressure within the coolant jacket and radiator at 
atmospheric level, a gas permeable water shedding filter 5 is arranged as 
shown, to permit the entry of air into and out of the system. 
However, this filter permits gaseous coolant to readily escape from the 
system, inducing the need for frequent topping up of the coolant level. A 
further problem with this arrangement has come in that some of the air, 
which is sucked into the cooling system as the engine cools, tends to 
dissolve in the water, whereby upon start up of the engine, the dissolved 
air tends to come out of solution and forms small bubbles in the radiator 
which adhere to the walls thereof and form an insulating layer. The 
undissolved air also tends to collect in the upper section of the radiator 
and inhibit the convention-like circulation of the vapor from the cylinder 
block to the radiator. This of course further deteriorates the performance 
of the device. 
European Patent Application Provisional Publication No. 0 059 423 published 
on Sept. 8, 1982 discloses another arrangement wherein, liquid coolant in 
the coolant jacket of the engine, is not forcefully circulated therein and 
permitted to absorb heat to the point of boiling. The gaseous coolant thus 
generated is adiabatically compressed in a compressor so as to raise the 
temperature and pressure thereof and thereafter introduced into a heat 
exchanger (radiator). After condensing, the coolant is temporarily stored 
in a reservoir and recycled back into the coolant jacket via a flow 
control valve. 
This arrangement has suffered from the drawback that when the engine is 
stopped and cools down, the coolant vapor condenses and induces 
sub-atmospheric conditions which tend to induce air to leak into the 
system. This air tends to be forced by the compressor along with the 
gaseous coolant into the radiator. 
Due to the difference in specific gravity, the above mentioned air tends to 
rise in the hot environment while the coolant which has condensed moves 
downwardly. The air, due to this inherent tendency to rise, tends to form 
pockets of air which cause a kind of "embolism" in the radiator and which 
badly impair the heat exchange ability thereof. 
With this arrangement the provision of the compressor renders the control 
of the pressure prevailing in the cooling circuit for the purpose of 
varying the coolant boilding point with load and/or engine speed 
difficult. 
U.S. Pat. No. 4,367,699 issued on Jan. 11, 1983 in the name of Evans (see 
FIG. 3 of the drawings) discloses an engine system wherein the coolant is 
boiled and the vapor used to remove heat from the engine. This arrangement 
features a separation tank 6 wherein gaseous and liquid coolant are 
initially separated. The liquid coolant is fed back to the cylinder block 
7 under the influence of gravity while the relatively dry gaseous coolant 
(steam for example) is condensed in a fan cooled radiator 8. 
The temperature of the radiator is controlled by selective energizations of 
the fan 9 which maintains a rate of condensation therein sufficient to 
provide a liquid seal at the bottom of the device. Condensate discharged 
from the radiator via the above mentioned liquid seal is collected in a 
small reservior-like arrangement 10 and pumped back up to the separation 
tank via a small constantly energized pump 11. 
This arrangement, while providing an arrangement via which air can be 
initially purged to some degree from the system tends to, due to the 
nature of the arrangement which permits said initial non-condensible 
matter to be forced out of the system, suffers from rapid loss of coolant 
when operated at relatively high altitudes. Further, once the engine cools 
air is relatively freely admitted back into the system. The provision of 
the bulky separation tank 6 also renders engine layout difficult. 
The rate of condensation in the condensor is controlled by a temperature 
sensor disposed on or in the condensor per se. 
Japanese Patent Application First Provisional Publication No. sho. 56-32026 
(see FIG. 4 of the drawings) discloses an arrangement wherein the 
structure defining the cylinder head and cylinder liners are covered in a 
porous layer of ceramic material 12 and wherein coolant is sprayed into 
the cylinder block from shower-like arrangements 13 located above the 
cylinder heads 14. The interior of the coolant jacket defined within the 
engine proper is essentially filled with gaseous coolant during engine 
operation at which time liquid coolant sprayed onto the ceramic layers 12. 
However, this arrangement has proven totally unsatisfactory in that upon 
boiling of the liquid coolant absorbed into the ceramic layers, the vapor 
thus produced and which escapes toward and into the coolant jacket, 
inhibits the penetration of fresh liquid coolant into the layers and 
induces the situation wherein rapid overheat and thermal damage of the 
ceramic layers 12 and/or engine soon results. Further, this arrangement is 
of the closed circuit type and is plagued with air contamination and 
blockages in the radiator similar to the compressor equipped arrangement 
discussed above. 
FIG. 7 shows in arrangement which is disclosed in U.S. Pat. No. 4,549,505 
issued on Oct. 29, 1985 in the name of Hirano. The disclosure of this 
application is hereby incorporated by reference thereto. For convenience 
the same numerals as used in the above mentioned Patent are also used in 
FIG. 7. 
This arrangement while solving the drawbacks encountered with the 
previously disclosed prior art has itself suffered from the drawbacks that 
when the engine is operated under high speed/load conditions, the boiling 
of the coolant in the coolant jacket 120 becomes so vigorous as to bump 
and froth to the degree that sufficient liquid coolant flows from the 
coolant jacket to the radiator 126 as to wet the interior of the latter 
mentioned device to the point of inhibiting the release of the latent heat 
of evaporation of the gaseous coolant. Viz., the liquid film on the wetted 
surfaces of the radiator act as an insulator which prevents the heat in 
the vapor from being readily released. This situation is highly 
undesirable in that the engine tends to be combusting large amounts of 
fuel per unit time at this time (ie. high speed/load operation) and thus 
induces the demand for a high radiator heat exchange efficiency. 
FIGS. 8 and 9 show an arrangement disclosed in U.S. Pat. No. 4,499,866 
issued on Feb. 19, 1985 in the name of Hirano which directed to 
overcomming the "boil-over" type problem discussed hereinabove. This 
arrangement includes a vapor manifold 232 which is mounted atop of a 
cylinder head which has a internal passage structure designed to limit the 
boiling froth which actually enters the manifold per se. The manifold 232 
as shown, has a collector section 234 which is located vertically above 
the vapor discharge ports 216 formed in the cylinder head. With this, any 
liquid coolant which precipitates out of the vapor flow due to the 
numerous changes in flow direction which occur before the flow reaches the 
outlet 238 of the manifold, tends to drain back down into the coolant 
jacket partially quelling the upwardly moving coolant froth and foam. 
However, as shown the overall height of the engine is increased by the 
provision of this type of manfifold and thus induces design problems when 
attempting the lower the bonnet line of an automotive vehicle wherein the 
engine is located in the forward section of the engine. 
The content of the above mentioned United States Patent is hereby 
incorporated by reference thereto. For ease of comparison the numerals 
used in FIGS. 8 and 9 differ from those used in the corresponding drawings 
of the said patent only by the addition of the value of 200 to each. Viz., 
numeral 10 becomes 210 etc. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a vapor manifold for an 
evaporative cooled engine which is compact and simple in construction and 
which suitably attenutes the transmission of coolant in its liquid state 
between the coolant jacket and the radiator of the system. 
In brief, the above object is achieved by a vapor manifold which is 
arranged to induce the coolant vapor to flow through a collector section 
thereof in a manner that the liquid droplets develop a velocity which 
tends to carry the same through a drain port formed at one end of the 
manifold. The vapor is caused to pass out through a vapor discharge port 
formed at an acute angle with respect to the direction in which the 
coolant flows through the collector section. This induces a flow pattern 
in the vapor flow which produces an angular acceleration which separates 
liquid coolant droplets from the vapor before the vapor passes out through 
the vapor discharge port. 
More specifically, the present invention takes the form of a cooling system 
for an internal combustion engine which includes a coolant jacket in which 
coolant is boiled and a coolant vapor produced; a radiator in fluid 
communication with the coolant jacket and in which the coolant vapor 
produced in the coolant jacket is condensed to its liquid form; and a 
vapor manifold interposed between the coolant jacket and the radiator, the 
manifold comprising: an elongate collector section which communicates with 
the coolant jacekt through a runner; means defining a liquid drain port at 
one end of the collector, the drain port being essentially aligned with a 
longitudinal axis of the collector section, the collector section being 
arranged so that the vapor from the branch runner enters the collector 
section and flows essentially along the longitudinal axis toward the drain 
port; means defining a vapor discharge port, the vapor discharge port 
being arranged in proximity of the drain port at a location upsteam of the 
drain port and at an angle with respect to the longitudinal axis, the 
vapor discharge port being fluidly communicated with the radiator; the 
arrangement of the drain port and the vapor discharge port being such as 
to define means for causing the vapor to be subject to an angular 
acceleration which causes liquid coolant entrained therein to be separated 
from the vapor before the vapor passes through the vapor discharge port.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 10 and 11 show an embodiment of the present invention. This 
arrangement as shown, takes the form of a manifold 300 having an enlongate 
collector section 302 which communicates with a plurality of vapor 
discharge ports (not shown) via branch runners 304. It will be noted that 
the cross sectional of the collector section 302 increases in the 
direction of the vapor discharge port 306 and the liquid coolant drain 
port 308 so as to accomodate the increased amount of vapor which tends to 
be introduced into the device with each succesive branch runner 304. 
The liquid coolant drain port 308 is located at one end of the manifold in 
a manner to be essentially alinged with the axis of the arrangement, while 
the vapor discharge port 306 is arranged to extend from one side of the 
manifold. In the instant embodiment the vapor discharge port 306 is 
arranged with respect to the axial direction of the collector section 302 
in a manner which defines an acute angle therewith. 
With this arrangement as the coolant vapor enters the collector section 302 
from the branch runners 304 it tends to flow in a manner which imparts 
sufficient velocity to the droplets of liquid coolant entrained therein 
that upon reaching the end of the collector whereat the drain and 
discharge ports 308, 306 are located the droplets are carried (as shown by 
broken line) under the influence of their own inertia toward and into the 
drain port 308 while the vapor (as shown in solid line) undergoes a change 
in direction which tends to induce a rotating flow pattern. This latter 
mentioned phenomeon imparts an angular acceleration to the liquid coolant 
in zone "A" which tends to induce a kind of "centrifugal" separation 
wherein the remaining droplets of liquid in the vapor flow tend to to 
"flung off" from the vapor flow and prevented from passing through the 
vapor discharge port along with the vapor per se. 
Although not shown, the drain port 308 can be connected to the coolant 
jacket in a manner to return the collected coolant thereto. Examples of 
connections which can be used to return the collected coolant may be found 
in copending U.S. patent application Ser. No. 654,222 filed on Sept. 25, 
1984 in the name of Hirano now U.S. Pat. No. 4,570,579 and Ser. No. 
751,537 filed on July 3, 1985 in the name of Hayashi et al.