Water box and expansion chamber device, e.g. for an internal combustion engine radiator

The water box and expansion chamber for the radiator of an internal combustion engine radiator may be moulded as a single piece. The water box (12) and the expansion chamber (11) are connected in the usual way near the top by a degassing duct. Near the bottom it is important to provide suction in the expansion chamber to ensure effective degassing. Suction may either be provided by a channel (21) enabling the main outlet flow of fluid from the radiator to entrain fluid from the expansion chamber, or it may be provided by a separate suction outlet (30) for connection to a pump. Different kinds of engine use different suction systems. The present invention allows both systems to be catered for by a single type of device in which the unwanted suction path is readily closed off, either during the original moulding operation (e.g. wall 31) or by means of a stopper (20) that provides a path when inserted in out orientation, but which closes a path when turned to another orientation.

The present invention relates to a water box and expansion chamber device 
(eg. a single moulded part) for use in a heat exchanger such as the 
radiator of an internal combustion engine cooling system. 
BACKGROUND OF THE INVENTION 
In such a device, the expansion chamber and the water box are generally 
interconnected by an upper passage which constitutes a degassing duct, and 
by a lower passage which provides a suction orifice. The degassing duct 
serves to trap bubbles of air or gas in the water box and coming from the 
cooling liquid and to discharge them into the expansion chamber in order 
to avoid the risk of "hot spots" in the engine block. 
To enable said degassing to operate, the expansion chamber is kept at a 
lower pressure than the water box by means of suction generated by the 
cooling liquid flowing out from the water box towards an outlet tube 
thereform and past the lower or suction orifice or passage. 
However, in many practical cases, the outlet tube is sufficiently bulky to 
require some special orientation to be able to fit in the space available. 
This can lead to the flow of liquid to the outlet tube creating back 
pressure rather than suction in the vicinity of the lower or suction 
orifice or passage. This hinders putting the expansion chamber at reduced 
pressure and prevents proper degassing of the liquid circulating in the 
cooling circuit. 
Preferred embodiments of the present invention provide a water box and 
expansion chamber device, preferably in the form of a single moulding, 
which avoids the above drawback, and in which degassing effectiveness is 
maintained regardless of the direction in which the outlet tube leaves the 
bottom of the water box. 
SUMMARY OF THE INVENTION 
The present invention provides a water box and expansion chamber device for 
a heat exchanger such as a radiator in the cooling circuit of an internal 
combustion engine, wherein the expansion chamber and the water box are 
connected by an upper degassing passage, wherein the bottom of the water 
box is provided with an outlet tube for fluid outlet from the heat 
exchanger, and wherein a communication channel connects the expansion 
chamber to said outlet tube, eg. substantially to the inlet thereof, while 
separating expansion chamber from the water box per se. 
Thus the suction developed in the expansion chamber by the communication 
channel is independent of the conditions of liquid flow in the water box 
immediately upstream from the outlet tube, since the communication channel 
connects the expansion chamber directly to the outlet tube. 
Preferably the communication channel points substantially parallel to the 
axis of the outlet tube where it opens out therein. 
This maximises suction of the liquid in the expansion chamber by the 
communication channel. 
The device may be used in two different applications that require differing 
modes of operation. Engine cooling circuits exist which are controlled by 
a thermostatically controlled valve which serves to short circuit the 
radiator while the temperature of the cooling liquid remains below a 
threshold value, for example in order to reduce the warming up period of 
the engine after a cold start. Putting the thermostatically controlled 
valve in the short circuit position generally means that the cooling is 
not degassed, since the degassing means are in the radiator which the 
valve is short circuiting. 
However, in some cases, particularly when the engine is a Diesel engine, it 
is desirable for the cooling liquid to be degassed even when the radiator 
is being short circuited. To do this, a direct connection is provided from 
the bottom of the expansion chamber to the suction side of a pump for 
circulating liquid in the cooling circuit. 
At the price of a very small and cheap modification during moulding or 
assembly (or both), the device in accordance with the present invention 
can be made for one or other type of expansion chamber suction.

MORE DETAILED DESCRIPTION 
Reference is made initially to FIGS. 1 and 2 which show a first embodiment 
of the invention, suitable for use in the first type of cooling circuit 
mentioned above (in particular for a gasoline engine). 
The device 10 in accordance with the invention comprises an expansion 
chamber 11 and a water box 12 which are made in a single piece, eg. by 
moulding. In the usual manner, the water box 12 has an open face delimited 
by a rim 13 for mounting on a tube plate 14 through which there pass the 
ends 15 of tubes 16 belonging to the core of a heat exchanger, eg. a 
radiator. 
The water box 12 communicates with the expansion chamber 11 both via a 
degassing duct or passage (not shown) which connects the top of the water 
box 12 to a portion of the expansion chamber 11 which is preferably below 
the level of liquid contained therein, and via a bottom orifice or passage 
17 through the wall 18 which separates the expansion chamber 11 from the 
water box 12. 
The bottom portion of the water box 12 is formed with a heat exchanger 
outlet tube 19 which may be moulded in one piece with the wall of the 
water box. The outlet tube 19 is in the form of a cylindrical stub (FIG. 
2) extending perpendicularly to the longitudinal mid plane A of the water 
box 12, ie. at right angles to the plane defined by the bundle of heat 
exchanger tubes, which is the same as being at right angles to the plane 
of FIG. 1. 
A radiator incorporating a water box and expansion chamber device 10 in 
accordance with the invention is used with an engine. When the engine is 
running, the cooling liquid flows through the water boxes and along the 
tubes of the heat exchanger, finally leaving via the ends 15 of the bottom 
tubes 16 into the bottom of the water box 12 and hence into the outlet 
tube 19 from the heat exchanger, as indicated by arrows in FIGS. 1 and 2. 
Thus, until it is deflected through a right angle to pass through the 
outlet tube 19, the liquid leaving the ends 15 of the bottom tubes 16 
flows substantially directly towards the the orifice 17 connecting the 
water box 12 to the expansion chamber 11. This liquid trajectory creates a 
local back pressure or pressure increase in the immediate surroundings of 
the orifice 17, and this excess pressure renders the degassing 
substantially ineffective, since degassing is only effective, as explained 
above, if the flow of liquid through the outlet tube 19 causes in 
expansion chamber 11 suction through the orifice 17. 
To remove this local overpressure effect around the orifice 17, the 
invention provides to close the orifice by means of a member 20 which 
constitutes a stopper having a communication channel leading from the 
inside of the expansion chamber 11 to the outlet tube 19. 
In the example shown in the drawing, the member 20 is in the shape of a 
circular disk whose periphery 22 is pressed from the water box side 
against a shoulder 23 around the rim of the orifice 17. A cylindrical 
skirt or flange 24 projects from the disk and is a tight fit in the 
orifice 17 through the wall 18. 
The channel 21 is delimited by a portion 25 of the circular disk which 
plugs the orifice 17. Said portion 25 is curved through substantially one 
fourth of a circle and serves a shield or screen by deflecting the fluid 
flowing out from the ends 15 of the bottom tubes 16 of the heat exchanger 
core away from the orifice 17. Fluid communication is maintained via a 
radial slot 26 formed through the skirt 24 and the disk 20 inside the 
portion 25. 
The opening of the channel 21 level with the inlet to the outlet tube 19 is 
now aligned with the direction of liquid flow therethrough. 
The member 20 is held in place in the orifice 17 by thrust from the tube 
plate 14 of the radiator core. Said thrust is transmitted by a rod or 
strut 27 which projects perpendicularly from the disk for the required 
distance. 
The member 20 is placed in the orifice 17 by insertion from the water box 
12 before the water box 12 is itself assembled on the tube plate 14 of the 
radiator core. 
The flow of liquid through the heat exchanger and into the outlet tube 19 
therefrom, provides suction in the channel 21, thereby reducing the 
pressure in the bottom of the expansion chamber 11 and promoting degassing 
from the liquid, as explained above. 
In FIG. 3, which shows a modified version of the device for use in a 
radiator in the second type of cooling circuit, in which degassing is 
possible when the thermostat valve is closed, the member 20 is turned 
through about 180.degree. in the orifice 17 such that the outlet from the 
channel 21 points away from the outlet tube 19 and is thus closed by the 
wall of the water box 12. The liquid leaving the the ends 15 of the bottom 
tubes 16 in the heat exchanger core thus reach the outlet tube 19 by 
flowing in the direction indicated by the arrows in FIG. 3, and thus 
without creating suction in the expansion chamber 11. Indeed there is no 
communication between the expansion chamber 11 and the water box 12 via 
the orifice 17. 
A cylindrical stub outlet tube 30 projects from the bottom of the expansion 
chamber 11, made in the same moulding operation as the rest of the 
expansion chamber 11. The outlet tube 30 is intended to communicate with 
the suction side of a pump for circulating the cooling liquid. It is 
suction produced by the pump that reduces the pressure inside the 
expansion chamber and ensures effective degassing of the liquid. 
In the version shown in FIG. 2, the tube 30 is present but plugged by a 
wall 31 which forms part of the same moulding as the tube 30 and the 
expansion chamber 11. 
Thus, to go from the first version to the second, two steps only are 
required: during moulding the plug wall portion 31 is omitted, and during 
assembly, the stopper member 20 is disposed in the orifice 17 through the 
wall 18 in such a manner that the communication channel 21 is plugged by 
the wall of the water box 12 opposite the outlet tube 19. 
Reference is now made to FIGS. 4 to 6 which show a variant embodiment of 
the invention, which differs from the embodiment shown in FIGS. 1 to 3 in 
that the stopper member 20 is replaced by a wall 40 which is moulded 
integrally with the expansion chamber 41 and the water box 42. The stopper 
wall 40 forms a part of the partition 43 separating the expansion chamber 
41 from the water box 42, and has a channel 44 for communication between 
the bottom part of the expansion chamber 41 and the heat exchanger outlet 
tube 45 which is integrally moulded with the water box wall and projects 
perpendicularly therefrom as in the embodiment shown in FIGS. 1 to 3. 
The channel 44 is delimited by a curved wall 46 having substantially the 
shape of one fourth of a sphere for example, similar to the curved wall 25 
of the first embodiment. 
A stub cylindrical tube 47 projects from the bottom of the expansion 
chamber 41 in a manner suitable for connection to the suction side of a 
pump for circulating cooling liquid. 
In a first version shown in FIG. 5, the tube 47 is closed by a wall 48 
which is integrally moulded with the tube 47 and with the wall of the 
expansion chamber 41, while in the FIG. 6 version the outlet tube 47 is 
open. In contrast the second, or FIG. 6 version, has the communication 
channel 44 closed by a wall 49 extending the wall 40, while the FIG. 5 
version has this channel open. 
Thus selection of one version or the other, is merely a matter of suitably 
selecting cores to put in the moulds during manufacture, with the moulds 
being good for either version.