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(11) | EP 0 921 284 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Improvements relating to the liquid cooled I.C. engines |
| (57) A liquid cooled internal combustion engine cooling system comprising a radiator 10,
and an impeller 18 mounted on a drive shaft 20 and forming part of the radiator assembly.
Preferably a compartment in the radiator header tank is 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 from the drive motor 12. |
[0001] 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 via flexible 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 crankshaft 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.
[0002] 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.
[0004] 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.
[0005] 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.
[0006] 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 where heat 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.
[0007] 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 pump speeds will be possible. This in general is a reverse of what is provided by the conventional arrangements.
[0008] 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 may be that operation of the impeller or an impeller to drive engine coolant via the heating system is required at times when engine cooling is not required, and the invention 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 eliminated and flow can be directed to other components of a vehicle or engine.
[0009] 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 eliminate 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.
[0010] 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 possibility and also that of using conventional belt drive without even a magnetic coupling, as long as the radiator location of the impeller is employed.
[0011] 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.
[0012] The header tank may have pump components included as part of unitary injection moulded or die-cast structure and additional components assembled thereto.
[0013] The invention is more particularly described with reference to the accompanying drawings in which:-
FIGURE 1 is a diagrammatic cut-away view showing an end portion of a radiator header tank provided with the invention;
FIGURE 2 is a diagrammatic 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 1;
FIGURE 5 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.
[0014] 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 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 drive motor, 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.
[0015] 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 the 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.
[0016] 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 pump housing 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.
[0017] The pump housing includes flange 28 which is bolted face to face against a like flange 30 on the header tank.
[0018] 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: essentially with the electric motor there will be no rotating part projecting to the exterior and the motor can be completely "canned".
1. A liquid cooled internal combustion engine cooling system comprising a radiator assembly
having a radiator, and an impeller mounted on a drive shaft and forming part of the
radiator assembly.
2. A system according to Claim 1 wherein the radiator comprises a header tank which is
adapted to form a chamber for the impeller.
3. A system according to Claim 2 wherein the chamber is closed by a plate carrying a
bearing and a seal for co-operation with the drive shaft.
4. A system according to any preceding claim wherein the drive shaft carries a separate
and distinct drive, which is preferably a motor such as an electric motor.
5. A system according to any preceding claim comprising a controller for controlling
the operation of the drive in response to predetermine engine temperature characteristics.
6. A system according to Claim 5 wherein the controller comprises part of an engine management
system for a vehicle and/or comprises a thermostat which monitors the engine temperature
of a vehicle.
7. A system according to Claim 5 or 6 wherein the controller enables an engine to reach
a desired operating temperature before actuating the motor thereby to commence cooling
of the engine.
8. A system according to any of Claims 5, 6 or 7 wherein the controller enables continued
operation of the pump after an engine ignition has been turned off, thereby to ensure
continued cooling of an engine.
9. A system according to any preceding claim comprising two or more impellers, and/or
valving arrangement allowing diversion of the coolant so that it does not necessarily
pass through the radiator.
10. A system according to Claim 9 comprising two or more impellers in parallel, or independent
of one another.
11. A system according to Claim 9 or 10 comprising two or more impellers in series with
one another thereby to provide a multiple stage pump.
12. A system according to any preceding claim wherein the impeller and motor are magnetically
coupled through a relatively stationary and relatively non-magnetic plate.
13. A system according to any preceding claim wherein the drive shaft comprises a pulley
operably having a drive belt for co-operation with drive means such as an engine crankshaft
thereby to drive the impeller.
14. A system according to any preceding claim wherein a separate chamber housing is provided
which is connectable to the radiator so as to form a complete unit.
15. A system according to any preceding claim wherein a radiator header tank is provided
having one or more pump components such as a chamber. inlet or outlet for example,
formed therein during manufacture.
16. A system according to Claim 15 wherein the header tank is formed by injection moulding
or diecasting to provide the one or more pump components.