Note: Descriptions are shown in the official language in which they were submitted.
CA 022~4822 1998-11-26
KJB/sjp~3290
IMPROVEMENTS RELATING TO THE LIQUID
COOLED I.C. ENGINES
This invention relates to liquid cooled internal combustion or I.C.
engines. It is conventional to provide a coolant circuit including a radiator
allowing heat exchange between the coolant and for example a fan driven flow
of ambient air. The coolant is driven from engine to radiator and vice versa viaflexible hoses which allow for relative movement of the engine and radiator, by
a so-called water pump having an impeller mounted on a drive shaft also
carrying a pulley. The impeller is located in a chamber in the engine, on the face
of the cylinder block adjacent the radiator, and the pulley is engaged by a vee
belt driven from the cr~nk~h~ft and often also serving to drive an alternator and
the fan, in the latter case possibly via an electric clutch allowing the fan to turn
or not according to control applied by an engine management system or in
simpler versions under the control of a thermostat sensing coolant temperature.
The impeller, drive shaft and a plate closing the impeller chamber and
containing bearing and seal form a single unit which is replaceable. The usual
reasons for replacement are leakage caused by chemicals, dirt or impurities in
the coolant, or wear caused either by long use, or quite frequently by improper
use such as over tightening the drive belt which places undue load on the
bearing or seal.
An object of this invention is to provide improvements over the prior art.
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CA 022~4822 1998 -11- 26
According to the one aspect of the invention there is provided a liquid
cooled I.C. engine cooling system comprises a radiator, and an impeller
mounted on a drive shaft and forming part of the radiator assembly.
Hence, a compartment in the radiator header tank, assuming a vertical
flow radiator in this instance, may be used as an impeller chamber, and the
chamber may be closed by a plate carrying a bearing and a seal for co-operation
with the drive shaft.
Preferably, the drive shaft carries a separate and distinct drive motor,
which will usually be an electric motor. The motor may be under the control of
an engine management system or a thermostat and this gives a completely new
control in engine management. Hitherto, as far as the applicants are aware, it
has only been the coolant fan which has been controlled in this way. The
significance of controlling the water pump by the same or a similar system is
that power utilization in driving the pump is avoided at times when the pump is
unnecessary, that is when the coolant temperature has not risen to a point whereheat exchange is required, and moreover rise in engine temperature to the
required range can be more rapidly controlled. These factors can lead to
substantially improved fuel consumption as compared to what is possible with
known designs. Additionally, the system can continue to cool an engine even
after the ignition has been turned off - for example to ensure a predetermined
non-operating temperature is reached.
Independence of drive from engine speed also allows water pump
operating speed to be selected in terms of efficiency. For example, when an
engine is idling and a vehicle is stationary in traffic, it may be desirable for the
pump to operate at maximum speed (assuming that speed variation is a
possibility with the chosen design) whereas when the vehicle is travelling lower
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CA 022~4822 1998-11-26
pump speeds will be possible. This in general is a reverse of what is provided
by the conventional arrangements.
Again, whilst the foregoing description is solely in relation to engine
cooling, the same possibilities exist where the coolant is used for other purposes
for example as part of the heating system of a vehicle. In such instances it maybe that operation of the impeller or an impeller to drive engine coolant via theheating system is required at times when engine cooling is not required, and theinvention contemplates the use of multiple impellers and/or valving
arrangements allowing diversion of the coolant according to requirements for
the different purposes. Multiple impellers can be used in parallel (effectively
multiple pumps) or in series thereby effectively to provide a multiple stage
pump. Accordingly, for a parallel arrangement or suitable valve arrangement,
coolant flow to the radiator can be restricted or elimin~ted and flow can be
directed to other components of a vehicle or engine.
Another possibility with the use of an electric motor is to make a
magnetic coupling between the impeller and the motor so that the plate carrying
the shaft bearing can be completely closed and again elimin~te risk of leakage to
the exterior. In the event of motor failure, the motor can be replaced without
affecting the integrity of the coolant system.
However, in a development of magnetic coupling, the drive motor may be
replaced by a pulley engaged with a drive belt so that the impeller is belt driven
for example from the engine crankshaft with a magnetic coupling to the impeller
and although this is not as readily susceptible of control, it may be considered to
have advantages as compared to the conventional arrangements and location of
the impeller and water pump. An aspect of the invention encompasses this
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CA 022~4822 1998 -11- 26
possibility and also that of using a conventional belt drive without even a
magnetic coupling, as long as the radiator location of the impeller is employed.
Instead of providing the impeller chamber in the header tank or like part
of the radiator, it may be located in a chamber housing connected to the radiator
in this case the chamber may also form part of a complete unit which is
replaceable in case of need.
The header tank may have pump components included as part of unitary
injection moulded or die-cast structure and additional components assembled
thereto.
The invention is more particularly described with reference to the
accompanying drawings in which:-
FIGURE 1 is a diagr~mm~tic cut-away view showing an end portion of a
radiator header tank provided with the invention;
FIGURE 2 is a diagr~mm~tic perspective view of a different embodiment;
FIGURE 3 is an exploded view showing the components used in the
Figure 2 construction;
FIGURE 4 is a side elevation of the arrangement shown in Figure l;
FIGURE S is an underneath plan view of the same;
FIGURE 6 is a section taken on the line VI-VI of Figure 4; and
FIGURE 7 is a block diagram of a system according to the invention.
Turning first to Figures 1 and 4 to 7, the embodiment illustrated therein
has the water pump located in one end of the header tank 10 of a vehicle radiator
associated with an I.C. engine. An electric drive motor 12 is mounted on one
end face of the header tank with a suitable interposed seal and bearings provided
CA 022~4822 1998-11-26
either in the header tank itself or in the drive motor construction. Coolant is
drawn in through the inlet 14 located axially and indeed co-axial with the drivemotor, and expelled through the outlet 16 which in this instance is of somewhat
of a "figure of 8" cross-section, thereby providing a pair of passages. This
coolant flow is caused by impeller 18 mounted on drive shaft 20 and housed in
an appropriate volute 22.
Figure 7 shows a schematic block diagram of a cooling system according
to the invention where it can be seen that motor 12 communicates with a
controller 32 such as an engine management system, which controller further
comprises a thermo couple 34 for monitoring ~he engine temperature. Of
course, multiple thermo couples can be used for monitor temperature at
different locations. Accordingly, controller 32 is used to actuate drive motor 12
thereby to effect pumping by impeller 18 as appropriate and/or as predetermined
dependent on the engine speed and/or temperature.
Turning next to Figures 2 and 3 wherein like reference numerals are used
as to those used in Figures 1 and 4-6, for like parts, the motor shaft 20 here
extends normal to the length of the header tank 12. The motor 12 is associated
with a cover 24 which provides a seal to the shaft 20, and the cover closes pumphousing 26 which forms an equivalent to the volute in the Figure 1 construction.The impeller chamber is formed in the pump housing and the impeller 18 lies in
that chamber which is closed by the cover 24.
The pump housing includes flange 28 which is bolted face to face against
a like flange 30 on the header tank.
It will be appreciated that any seal required by an electric motor is much
simpler than one required where a shaft is required to project to a drive pulley:
CA 022F74822 1998-11-26
essentially with the electric motor there will be no rotating part projecting to the
exterior and the motor can be completely "canned".
Whilst the specific embodiments described use centrifugal flow impellers,
this is not essential and axial flow or mixed flow arrangements are possible andmay be advantageous where space considerations are critical.
Further, whilst the invention has been specifically described in relation to
location of the impeller in the radiator header tank, different locations can beprovided around the radiator to suit particular requirements particularly in terms
of space considerations.
