Cooling system controller for internal combustion engines

A cooling systems controller for internal combustion engines having two circuits of cooling water for cylinder head side and cylinder block side, each of two circuits being provided with a radiator, a water jacket, a water pump, a conduit, a return passageway, a bypass passageway, a mixing valve, and a motor fan; two heater circuits being provided so as to branch from and return to said main two cooling water circuits, said heater circuits being provided with a first selector valve to junction them and a second selector valve to separate them, said selector valve having a function to supply the higher temperature water from either of two water circuits to a heater radiator by the signals from a control unit for judging which temperature of two circuits is higher, thereby making it possible to obtain more rapid heating effect at the time immediately after starting up the engine without reducing the heating efficiency during normal runs of vehicle.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a cooling system controller for internal 
combustion engines. 
2. Prior Art 
It is a daily experience matter that the heating efficiency of a heater is 
not high at the time immediately after starting up the engine of vehicles. 
This is because, as stated in the Japanese Laid-open Utility Model 
Bulletin Jitsu-kai-sho No. 59-139516 (139516/1984), conventional heaters 
for vehicles use the engine cooling water as the heat source, and 
consequently, the heater does not supply warmed air until the time when 
the temperature of cooling water becomes fully high. Namely, the warm-up 
character of engine has a great influence on the efficiency of heater. 
A device which intends to improve the efficiency of heater is disclosed in 
the Japanese Laid-open Patent Bulletin Toku-kai-sho No. 60-19912. The 
above improvement relates to a heater for an engine having two separated 
cooling water circuits, that is, a circuit including a water jacket 
provided at the cylinder-head side and a circuit including a water jacket 
provided at the cylinder-block side. In the conventional heaters such as 
mentioned in the above literature, the heater circuit is by-passed from 
the cylinder-block side circuit, this is because, in the two-circuits 
cooling system, the temperature at the head side is generally maintained 
lower than the temperature at the block side. But, at the time immediately 
after starting up the engine, the rise of temperature is more rapid at the 
head side than at the block side, as the head side is positioned more 
closely to the combustion chamber which is the main heat-generating 
portion. Therefore, as far as concerned with the heating effect, the 
conventional heater of aforementioned type is disadvantageous. 
Incidentally, the heating effects can be improved by combining the bypass 
valve disclosed in the prior art of said Jitsu-kai-sho No. 59-139516 with 
the bypass in the circuit on the block side disclosed in another prior art 
of said Toku-kai-sho No. 60-19912. By this way, the flow rate of the 
heater circuit can be increased and the heat radiating efficiency of the 
heater radiator can be improved by closing the bypass. But the amount of 
heat radiated from the heater cannot be greater than the amount of heat 
the cooling water receives from the heat generating section. It is also 
clear that the water on the heat side is at a higher temperature because 
the greatest portion of the heat generated immediately after start-up is 
from around the combustion chamber. Thus, the above improvement cannot but 
be disadvantageous. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide an improved controller 
for the two-circuits cooling system, which can avoid the drawback of the 
conventional system that the good heating effect is not obtained at the 
time immediately after starting up the engine, namely, to provide a 
controller which has the improved heating effect at the time immediately 
after starting up the engine, without reducing the efficiency of heater 
radiator at the time of normal running. 
In accordance with the present invention, the cooling system has the first 
and second water jackets, the first and second water pumps, the first and 
second conduits, the first and second return passageways, the first and 
second by-pass passageways, the first and second mixing valves, the first 
and second radiators, and the first and second motor fans. At the 
downstream side outlet ports of said first and second jackets, the first 
and second heater circuits are branched respectively. Said first and 
second heater circuits are junctioned by the first selector valve disposed 
at the upperstream of the heater radiator, are separated by the second 
selector valve disposed at the downstream of said heater radiator, and 
returns to a main water circuit respectively at the upperstream of said 
first or second water pump and at the downstream of said first or second 
mixing valve. Said first and second selector valves have the function to 
feed water of higher temperature out of water in said first or second 
water jacket or to shut off both water flows, in accordance with the 
signal from a control unit having function to detect the temperature at 
the outlet port of the downstream of said first and second water jackets 
by a sensor and to compare them. 
When the heater is unnecessary, both of the first and second selector 
valves are closed and water does not flow in the heater circuit. When the 
heater is necessary, the control unit judges either temperature of the 
temperatures at the cylinder head side and the cylinder block side, and 
controls the opening and closing of the first and second selector valves 
so that the water having higher temperature is fed to the heater circuit. 
Namely, the selector valves opens the cylinder head side at the time 
immediately after staring up the engine, as the temperature at the 
cylinder head side closer to the combustion chamber rises more rapidly. 
When the temperature at the cylinder block side becomes higher than the 
temperature at the cylinder head side, the selector valves close the 
cylinder head side and open the cylinder block side. Thus, by the present 
invention, it is possible to make the heater operation effective in the 
time immediately after start-up the engine without degrading the 
efficiency of heat radiator during normal run. 
The foregoing and other objects, features and advantages of the present 
invention will be understood more clearly and fully from the following 
detailed description of preferred embodiments with reference to the 
attached drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring to FIG. 1 and FIG. 2, there is shown an embodiment of the present 
invention. In a cooling system controller 1 for the internal combustion 
engines, the first and second heater circuits 8 and 9 are led from the 
outlet port of the first water jacket 2 on the head side and the outlet 
port of the second water jacket 3 on the block side respectively to 
combine them together; the first selector valve 10 is disposed at the 
junction, a heater radiator 7 is disposed downstream of the valve; the 
water stream is further diverted to circuit 12 which leads the stream to 
upstream of the second water pump 11 on the block side and circuit 14 
which leads the stream to upstream of the first water pump 13 on the head 
side; the second selector valve 15 is disposed at the point of diversion, 
and said first selector valve 10 is able to shut off the water coming from 
both the block side and the head side and has the function of supplying 
either of the water selectively to heater radiator 7 (A side closed, B 
side closed: A side open, B side closed: A side closed, B side open). 
A second selector valve 15, interlocked with the first selector valve 10, 
has the function of returning the water which has passed through the 
heater radiator 7, to the original water circuit. Also temperature sensors 
4 and 5 are provided at the outlet port on the head side and the outlet 
port on the block side respectively so as to send their signals to control 
unit 6. The first and second conduits 16 and 17 connect the outlet ports 
of water jackets 2 and 3 and the inlet ports of the first and second 
radiators 18 and 19 respectively. The return passageways 20 and 21 connect 
the outlet ports of the first and second radiators 18 and 19 and the first 
and second water pumps 13 and 11 respectively. The first and second bypass 
passageways 22 and 23 branch from the first and second conduits 16 and 17 
and communicate with the first and second return passageways 20 and 21 
respectively. The first and second mixing valves 24 and 25 are located at 
the junction of the first and second return passageways and the first and 
second bypass passageways 22 and 23 and mix the cooling water from each 
passageway to return it to the first and second water pumps 13 and 11. The 
first and second motor fans 26 and 27 feed cooling air to the first and 
second radiators 18 and 19 respectively. 
The first water jacket 2 on the head side and the second water jacket 3 on 
the block side have the same temperature at the time immediately after 
start-up of the engine. Then, at the beginning stage when the engine is 
warmed up by repeating combustion, the main heat generating portion is the 
combustion chamber, and the temperature rises more rapidly at the first 
water jacket 2 on the head side. If the heater is switched on at this 
time, control unit 6 compares the signals from the temperature sensors 4 
and 5, judges that the temperature of the water on the head side is 
higher, and opens the first and second selector valves 10 and 15 to the 
head side (A side). 
When the engine is sufficiently warmed up, the water on the head side is 
maintained at a lower temperature than on the block side by the action of 
the first and second mixing valves 24 and 25. In the process to this 
stage, the magnitude of signals of the temperature sensors 4 and 5 are 
reversed and the water stream is changed over so that the water on the 
block side (B side) flows to heater radiator 7 thereafter. When the heater 
is switched off, the first and second selector valves 10 and 15 are closed 
both on the head side and the block side. Thus, the heater works more 
rapidly in the time immediately after start-up because of the heat being 
radiated from the higher temperature water on the head side, while the 
heat radiation efficiency becomes high in the normal running state. 
FIG. 2 shows a second embodiment, which is a system to increase the heater 
flow rate by providing the first and second shut-off valves 28 and 29 for 
shutting off the flow in the bypass passageways only during the warmup 
time of the engine, in the first and second bypass passageways 22 and 23. 
The function and effect of this system is same as in the aforementioned 
first embodiment. The same effect can be achieved by a system in which the 
first and second selector valves 10 and 15 change over only the A side and 
the B side and another ON-OFF valve or a throttle valve is provided at the 
position between the confluence of the first and second selector valves 10 
and 15 and the point of diversion. 
It should be understood that, although the preferred embodiment of the 
present invention has been described herein in considerable detail, 
certain modifications, changes, and adaptations may be made by those 
skilled in the art and that it is hereby intended to cover all 
modifications, changes and adaptations thereof falling within the scope of 
the appended claims.