DESCRIPTION

The present invention relates to a water pump for displacing a cooling liquid of an internal combustion engine for motor vehicles or other uses.

More particularly, the invention relates to the system for rotating the shaft of a water pump applied in internal combustion engines and particularly to water- cooled engines, both industrial and commercial, and for both small and large vehicles.

The task of a water pump applied to an internal combustion engine is to move the cooling liquid within the cavities of the engine block and cylinder head (hereinafter called "cylinder block") . The cooling liquid is circulated through a heat exchanger (radiator) and, while cooling, removes heat produced by the combustion of the fuel introduced into the combustion chambers .

Usually, the positioning and shape of the water pump (Figure 1) is decided by the engine designers. Consequently, the water pump can be realized in any possible functional form, while maintaining its functioning principle which is common to all types.

Figures 2-4 schematically show one of the many types of water pump that can be made.

The water pumps, like the engines, must also be properly designed and be reliable enough to ensure that the internal combustion engine works properly, since if the water pump fails unexpectedly, the engine risks to be seriously damaged. The water pump in an internal combustion engine is of major importance, and it therefore appears to be an indispensable component for water-cooled engines, and above all it must be reliable over time.

A common water pump is normally made of components assembled together to constitute the assembly of the pump .

Figure 1 shows an engine 100 of known type, in particular an internal combustion engine, which rotates a driving shaft 101 owing to combustion of a fuel. Via a transmission system, not illustrated, the driving shaft 101 drives the wheels of a vehicle on which the engine 100 is mounted.

A pulley is further fixed to the driving shaft 101, a belt 102 being wound on the pulley, so that the driving shaft 101 moves the belt 102.

The belt 102 is also wound on a pulley 103 keyed on a shaft 104. As will be more fully described below, the shaft 104 supports an impeller of a pump suitable for circulating a cooling liquid. This impeller is housed inside a pump body 105, which is fixed to a cylinder block 106 of the engine 100.

The structure of the pump is shown in detail in Figures 2 to 4.

The pulley 103 is visible in Figure 3; the pulley 103 is usually made of steel, obtained by moulding or sintering .

The pump body 105 can be made of aluminium, cast iron, steel or plastic (thermosetting) .

Reference number 107 indicates an impeller, which can be made of plastic, steel (using pressed steel) or cast iron .

Reference number 108 indicates a bearing made of alloy steel capable of withstanding heavy and long-lasting loads due to the tension of the belt.

Reference number 109 indicates a mechanical seal, consisting of a steel casing internally of which carbon discs or the like are housed. These discs, being pushed against each other, do not allow passage of the cooling liquid .

The pulley 103 is rotated by the driving shaft 101 by means of the belt 102. The pulley 103 serves to transmit the rotational motion to the shaft 104 on which the bearing 108 is mounted.

The shaft 104 in turn rotates the impeller 107 of the pump for circulating the cooling liquid. The impeller 107 is designed with a special shape. Its function is to move the cooling liquid inside the cavities of the cylinder block 106 of the engine 100.

The bearing 108 enables the shaft 104 to rotate with respect to the pump body 105, such as to move the impeller 107.

The pump body 105 enables connection of the water pump assembly, i.e. the pump complete with all its components, to the cylinder block 106.

The mechanical seal 109 is made of two parts: a stationary part which is mounted on the pump body 105 and a movable part which is mounted on the shaft 104. The stationary part and the movable part of the mechanical seal 109 are pushed against each other and do not allow the cooling liquid to come into contact with the bearing 108. The above-described water pump has the sole task of displacing the cooling liquid inside the cylinder block 106 of the engine 100, in order to remove heat generated by the combustion of fuel. Ultimately, for this to be achieved, the impeller 107 has to be rotated.

By rotating, the driving shaft 101 moves the transmission belt 102.

Said belt, as it moves, rotates the pulley 103 which is fixed to the shaft 104 associated to the bearing 108. Since the impeller 107 is fixed on the shaft 104 of the bearing 108, as is the pulley 103, the impeller 107 also rotates solidly with the shaft 104.

The rotation of the impeller 107, as described above, displaces the cooling liquid internally of the cylinder block 106 of the engine 100.

In summary, Figure 3 illustrates the classic design of a water pump, in which the impeller 107 is moved via a built-in bearing 108 protected against the invasion of the cooling liquid by the seal 109. A pulley 103 is forcedly keyed on the left side of the bearing, the pulley 103 being in turn rotated by a belt 102 connected to a pulley mounted directly onto the driving shaft. The whole is then fixed to the cylinder block via the pump body 105.

This system has definitely a very serious drawback, which is that it is permanently uncontrollably connected to the rotation of the drive shaft. This means that the engine must generate energy to move the pump shaft in order to displace the engine cooling liquid.

In other words, the water pump described above exhibits two major drawbacks. Firstly, the water pump group is constantly in motion, even when the functional conditions of the engine do not require it. The pump impeller is in fact rotated, consequently subtracting energy from the engine, even when the engine temperature is still relatively low, i.e. when it would not be strictly necessary to circulate the cooling liquid.

In addition, the maximum working life of the water pump assembly is established a priori, when designing the bearing .

An object of the invention is to improve the devices for circulating a cooling liquid in an engine.

A further object is to provide a device for circulating a cooling liquid in an engine, which device has low energy consumption.

A further object is to provide a device for circulating a cooling liquid in an engine that can be activated only when needed.

According to the invention, there is provided a device comprising a pump for circulating a cooling liquid in an internal combustion engine, the pump comprising an impeller, characterized in that the device further comprises a driving element connected to the pump, the driving element being movable by the exhaust gases produced by the internal combustion engine such as to rotate the impeller of the pump.

Owing to the invention, it is possible to use the energy of the exhaust gases generated by the internal combustion engine to rotate the impeller of the pump and thus to circulate the cooling liquid in the internal combustion engine. This enables recovery of energy that would otherwise be dissipated when the exhaust gases are released into the external environment.

In addition, there is no longer any need to subtract energy from the internal combustion engine for driving the impeller of the pump, as was the case in traditional devices. The energy produced by the internal combustion engine can be usefully exploited for other purposes.

As the impeller of the pump is no longer directly coupled to the internal combustion engine, it is possible to operate the impeller of the pump only when needed, i.e. only when the cooling liquid is to be circulated in order to cool the engine. If the engine temperature is sufficiently low, as happens for example at start-up, the impeller of the pump can be left stationary, even when the engine is operating.

The invention will be better understood and carried out with reference to the accompanying drawings, which illustrate some embodiments of the invention, by way of non-limiting example, in which:

Figure 1 is a perspective view schematically showing an engine according to the prior art;

Figure 2 is an anterior front view of a pump assembly for circulating a cooling liquid in an engine, according to the prior art;

Figure 3 is a section view of the pump assembly of Figure 2;

Figure 4 is a posterior front view of the pump assembly of Figure 2;

Figure 5 is an anterior front view of a device for circulating a cooling liquid in an engine;

Figure 6 is a section view of the device of Figure 5; Figure 7 is a posterior front view of the device of figure 5;

Figure 8 is a perspective view of a device for circulating a cooling liquid in an engine, according to an alternative embodiment;

Figure 9 is a sectioned perspective view of the device of Figure 8 ;

Figure 10 is a side view of the device of Figure 8 ;

Figure 11 is a side view of the device of Figure 8, taken from the opposite side with respect to Figure 10. With reference to Figures 5 to 7, a device 1 is shown, comprising a pump for circulating a cooling liquid in an internal combustion engine, i.e. a water pump. The water pump according to the invention includes a number of components equal to those of the known water pump. These components, assembled with some new components, constitute the assembly of the new water pump.

As shown in Figure 6, the device 1 comprises a cover 2, a turbine 3, a lubrication hole 4, a pump body 5, a transmission shaft 6, at least a bushing 7, a mechanical seal 8 and an impeller 9 of the pump.

The device 1 further comprises a conduit 10, shown in Figure 7, for directing the exhaust gases towards the turbine 3.

The cover 2 is a specific component that is sold in various shapes, coupled with the turbine 3.

The turbine 3 is a specific component that is sold in various shapes, coupled with the cover 2.

The pump body 5 may be similar or in some cases identical to the pump body of the traditional pump assemblies .

The transmission shaft 6 can be made of common alloy steel .

The bushing 7 is usually made of alloy brass specific to these applications.

The mechanical seal 8 is identical to the mechanical seal of known pump assemblies.

The impeller 9 of the pump is identical to known pump impellers .

The cover 2 has an internal section that directs the exhaust gases coming from the internal combustion engine through a plurality of holes obtained in the cylinder block thereof, to an area of the turbine 3 known as the ' volute ' .

The cover 2 acts as a casing for housing a turbine impeller .

The turbine 3 serves for rotating the transmission shaft 6.

The pump body 5 serves for solidly connecting the pump assembly (i.e. the pump complete with all components thereof) to the cylinder block of the engine.

The transmission shaft 6 serves for rotating the pump impeller 9.

The bushing 7 is for supporting the transmission shaft 6 during rotation thereof.

The mechanical seal 8 is made of two parts, namely a stationary part mounted on the pump body 5 and a movable part mounted on the transmission shaft 6. The mechanical seal 8 prevents the cooling liquid from coming into contact with the bushing 7.

The impeller 9 of the pump is designed with an appropriate shape. Its function is to set the cooling liquid in motion internally of the cavities of the engine cylinder block.

The device 1 further comprises a choke valve, not illustrated, which serves to regulate the quantity of fumes or exhaust gases passing through the turbine 3. The choke valve is a commercially-available component of a known type.

The functioning of the novel type of water pump is based on application of a turbine 3 to the transmission shaft 6 of the water pump, for the purposes of rotating an impeller, using the residual energy possessed by the engine exhaust fumes.

The combustion residues, commonly known as fumes, are expelled at high speed from the head of the cylinder block through suitable holes.

Said fumes cross the choke valve, not shown in the Figures, which is capable of controlling the amount of fumes to let pass. This regulation occurs through a temperature value. This temperature value is detected by the combination of engine head temperature and cooling liquid temperature.

When the temperature reaches 90 °C (or another predetermined value) , the choke valve will be at its maximum aperture, thereby allowing the maximum amount of fumes to pass through.

When the temperature is low (below a value to be determined) , then the choke valve is fully closed and will not allow any amount of fumes to pass.

The fumes enter the device 1 through the conduit 10 and enter the chamber commonly known as the volute. Owing to their high speed, the fumes rotate the turbine 3.

More precisely, the fumes coming from the conduit 10 enter the turbine 3 and rotate the impeller thereof.

The transmission shaft 6 is fixed relative to the turbine 3, or more precisely relative to the impeller thereof. This shaft rotates inside the bushing 7, and is lubricated by the oil through the holes 4.

As the impeller 9 of the pump is also fastened to the transmission shaft 6, the impeller 9 will also rotate together with the transmission shaft 6, thereby displacing the cooling liquid in the cavities of the engine cylinder block.

In summary, the solution found, represented in Figures 5 to 7, definitely overcomes the drawback described for the traditional pump as explained below. The exhaust gases of the engine, which are full of energy due to combustion, by entering through the conduit 10 suitably shaped and coupled with the cover, rotate the impeller of the turbine 3. The turbine impeller is fixed relative to the shaft 6 supported by the bearings 7. The bushings 7 are oil-lubricated through the holes 4 and are protected by the engine cooling liquid by the seal 8. The shaft 6 in turn rotates the impeller 9 which is fixed relative to the shaft 6, thereby displacing the cooling liquid of the engine. The assembly is fixed to the cylinder block of the engine via the pump body.

The proposed solution certainly entirely obviates the problem of keeping the impeller in rotation, as it is directly controllable through the quantity of exhaust gases. The impeller of the pump can be rotated at the required time, by causing the impeller to rotate at a certain required rotational speed, by means of a circuit, connecting a thermometer which detects temperature of the liquid exiting the engine cylinder block with a valve that regulates the quantity of exhaust gas flow.

This circuit is not shown because it contains no technical innovation; in fact it is already used for other applications.

A further advantage is to use the residual energy possessed by the exhaust gases without having to produce more; in economic terms, this means consuming less, while in the ecological sense it causes less pollution. The substantial difference between the invention and the prior art essentially consists in that the impeller of the cooling liquid is rotated in two different ways: in the prior art by a belt directly connected to the pulley and keyed directly on the driving shaft, while in the invention a turbine is used, which is used by the exhaust gases of the engine combustion itself.

In summary, a turbine impeller is used, the turbine impeller being capable of using the energy of exhaust gases coming from the combustion that occurs in the engine or from other sources for rotating the impeller of the water pump for motor vehicles or other.

In the known system, the water pump, and thus the impeller of the pump, is moved by the transmission belt which is directly and constantly connected to the driving shaft.

In the new system, rotation of the water pump and therefore of the pump impeller is obtained via a turbine 3 rotated by the exhaust gases of the internal combustion engine.

Owing to this substantial difference, it can be assumed that the two systems for rotating the water pumps are profoundly different from one another. For this reason the relative water pumps are also different from one another .

By comparing the two types of pump, the system according to the invention surely enables obviating some drawbacks in comparison with those of the known type.

The invention provides multiple benefits, including:

1. The pump starts up only when the temperature exceeds predetermined values.

2. An improved engine performance is obtained.

3. There is a reduction in fuel consumption.

4. The quantity of CO ₂ emitted into the atmosphere is reduced .

5. Maintenance costs are reduced.

6. A high degree of reliability is achieved in setting the water pump in rotation.

With reference to point 1 above, owing to the choke valve for the fumes, the pump actually operates only when the combined value of the temperature coincides with the operating temperature. At this point, the valve begins to open and then allows the fumes to pass.

At this point, the fumes begin to turn the turbine and thus the impeller of the pump, which in turn displaces the cooling liquid.

When the temperature falls below the operating temperature, the system no longer requires movement of the cooling liquid and thus the choke valve closes and prevents the passage of fumes. Thus the turbine rotation halts and the water pump is stopped. With reference to the advantages referred to in points 2 and 3, engine performance increases because the engine does not generate energy continuously for rotating the water pump. This naturally means lower fuel consumption. As the engine uses less fuel, a smaller amount of CO ₂ will be released into the atmosphere. This advantage is perfectly in line with EU directives.

Since the bearing which determines the working life of the known-type water pump assembly has been removed, it follows that the duration of the water pump is no longer limited by the working life of the bearing and the frequent replacements of the latter. This leads to savings in maintenance costs.

The new system is more reliable than the known system, by virtue of the fact that the rotation motion is no longer transmitted by the transmission belt, which if broken could cause significant damage to the engine.

Figures 8 to 11 show an alternative embodiment of a device for circulating a cooling liquid, particularly water, internally of an internal combustion engine so as to cool the engine. This device is indicated by the reference number 11.

The device 11 comprises a pump for displacing the cooling liquid. The pump in turn includes an impeller 19, shown in Figure 9. The impeller 19 is fixed to a shaft 16 by a connection enabling the impeller 19 to rotate together with the shaft 16. The connection between the impeller 19 and shaft 16 can be removable, for example a threaded connection.

The impeller 19 can be mounted in particular to a first end of the shaft 16. In this case, a threaded shank is obtained on the first end of the shaft 16, on which shank the impeller 19 is screwed. The threaded shank projects from a frustum-conical portion of the shaft 16, which enables centring the impeller 19 with respect to the shaft 16.

The shaft 16 is rotatably supported by a support element, which in the illustrated example includes a bearing 17.

The device 1 further comprises a turbine arranged for rotating the shaft 16 around the longitudinal axis thereof. The turbine comprises an impeller 13 shown in Figure 9. In particular, the impeller 13 of the turbine can be mounted at a second end of the shaft 16, the second end being opposite the first end that supports the impeller 19 of the pump.

The impeller 13 of the turbine is connected to the shaft 16 by connecting means that enable the impeller 13 of the turbine to rotate together with the shaft 16. The connecting means can be removable and may include, for example, a threaded connection.

In the example shown, the impeller 13 of the turbine is screwed onto a further threaded shank obtained at the second end of the shaft 16. The further threaded shank projects from a respective frustum-conical portion of the shaft 16, which enables centring the impeller 13 of the turbine with respect to the shaft 16.

The impeller 13 of the turbine is rotatable internally of a casing 12, which can be considered as a stator or a cover .

As illustrated in Figure 8, a conduit 20 opens into the casing 12, the conduit 20 being connected, through an arrangement of conduits that are not illustrated, with one or more discharge holes of one or more cylinders of the internal combustion engine. During operation of the internal combustion engine, a combustion reaction occurs in each cylinder and generates exhaust gases or fumes, which exit from the corresponding cylinder through one or more discharge holes. These discharge holes communicate with the conduit 20 such as to convey the exhaust gases into the casing 12.

The casing 12 is further provided with an opening through which the exhaust gases can exit, after interacting with the turbine impeller 13. A hub of the turbine impeller 13 projects into the opening, said hub being fixed to the shaft 16. An annular opening 21, shown in Figure 9, is defined between the hub of the impeller 13 and the casing 12. By means of the annular opening 21, the exhaust gases can exit the turbine.

The bearing 17 is arranged within a containing body 22 delimited by a side wall extending around the longitudinal axis of the shaft 16. The side wall can have a substantially cylindrical shape.

The side wall of the containing body 22 is distanced from a lateral surface of the bearing 17, such that between the bearing 17 and the containing body 22 a chamber 23 is at least partially defined, as shown in Figure 9. The chamber 23 can be filled with cooling liquid such as to prevent the temperature of the bearing 17 from increasing excessively.

The device 11 comprises an inlet conduit 26 for the inlet of the cooling liquid. The cooling liquid comes, for example, from a radiator of the vehicle on which the device 11 is mounted. In this way, the cooling liquid has a relatively low temperature when it enters the device 11.

In the illustrated example, the inlet conduit 26 opens into the side wall of the containing body 22, such that the cooling liquid enters the chamber 23 to cool the bearing 17.

The chamber 23 also extends internally of a stator body 15 in which the impeller 19 of the pump is housed. The stator body 15 is fixed to the containing body 22 so that the inside of the stator body 15 communicates with the interior of the containing body 22. Thus the chamber 23 is defined, which extends internally of the stator body 15 and the containing body 22.

The stator body 15 can be secured to the containing body 22 via a connecting system that is removable and fluid- tight. In the illustrated example, the stator body 15 is provided with a flange that abuts against a further flange projecting from the side wall of the containing body 22. One or more seal rings can be interposed between the two flanges. The flanges of the stator body 15 and the containing body 22 are then joined together, for example by screws.

The containing body 22 is interposed between the stator body 15 and the casing 12 that houses the turbine impeller 13.

The casing 12 is fixed to the containing body 22 by fastening means, for example of a removable type. In the embodiment shown in Figures 8 to 11, the casing 12 is provided with a flanged end that abuts against a corresponding flanged end of the containing body 22. The two flanged ends are then joined together, for example by ties, screws or clamps, not illustrated, or with other types of connecting elements.

The device 11 further comprises an outlet conduit 27 through which the cooling liquid can be sent to the engine components to be cooled, after interacting with the impeller 19 of the pump.

In the example shown, the outlet conduit 27 is connected to the stator body 15 so as to receive the cooling liquid coming from inside the stator body 15.

The device 11 further comprises a sealing element 18 suitable for preventing the cooling liquid present in the chamber 23 from entering the bearing 17. The sealing element 18 can include a mechanical seal similar to the mechanical seal 8 shown in figure 6.

A communicating conduit 24 is further provided for connecting the inside of the bearing 17 with the environment outside the containing body 22. During operation of the device 11, the communicating conduit 24 is intended to be placed in a vertical position. The communicating conduit 24 causes any quantities of cooling liquid which have penetrated internally of the bearing 17, in a case of wear or poor functioning of the sealing element 18, to exit the bearing 17.

The communicating conduit 24 opens into a lower region of the bearing 17 so that any cooling liquid eventually accumulated in the lower region of the bearing 17 can exit through the communicating conduit 24 owing to the gravity force.

An additional communicating conduit 25 is also provided, shown in Figure 11, through which the interior of the bearing 17 can communicate with the environment outside the containing body 22.

During operation of the device 11, the further communicating conduit 25 is arranged in a horizontal position. The further communicating conduit 25 ensures that pressure inside the bearing 17 is the same as the atmospheric pressure. This prevents a depression from being created internally of the bearing 17 in a case of exit of any cooling liquid through the communicating conduit 24. A depression might prevent exit of further quantities of cooling liquid from the communicating conduit 24.

A valve, not illustrated, can be positioned along the arrangement of conduits that connect the conduit 20 with the exhaust holes in the engine, the valve being arranged for regulating the quantity of exhaust gas that is sent to the turbine. This valve can be similar to the choke valve described with reference to Figures 5 to 7. The valve can be controlled by a control circuit that, based on the cooling liquid temperature and the engine temperature, controls the position of a shutter of the valve, such as to control the amount of exhaust gas that is sent towards the turbine of the device 11.

During operation, the temperature inside the internal combustion engine naturally tends to rise. When the control circuit decides that the temperature of the internal combustion engine has increased excessively, the valve is opened to allow exhaust gases to enter the device 11 through the conduit 20. The exhaust gases are then sent inside the casing 12 and strike the impeller 13 of the turbine. The exhaust gases transfer energy to the turbine impeller 13, which is thus rotated. After transferring energy to the impeller 13, the exhaust gases exit from the casing 12 through the annular opening 21 and are processed in a known way before being released into the atmosphere.

When the impeller 13 of the turbine rotates, the shaft 16 connected to the impeller 13 is also rotated relative to the bearing 17. Since the impeller 19 of the pump is fixed relative to the shaft 16, when the shaft 16 is rotated, so is the impeller 19 of the pump. The impeller 19 of the pump circulates the cooling liquid, which is sent from the chamber 23 to the engine components to be cooled through the outlet conduit 27.

The temperature of the engine is thus lowered.

The cooling liquid reaches the chamber 23 through the inlet conduit 26, after being cooled in the radiator. Before interacting with the impeller 19 of the pump, the cooling liquid which is in the chamber 23 cools the bearing 17, such as to prevent the bearing 17 from reaching excessive temperatures also due to the heat released by the exhaust gases.

The exhaust gas temperatures are typically at temperatures of about 220-230°C when entering the device 11. The temperature of the bearing 17 should advisedly remain below 100-110°C.

The device 11 enables obtaining the advantages described above with reference to the device 1 shown in Figures 5 to 7. In particular, the device 11 can send the cooling liquid to the internal combustion engine using part of the residual energy contained in the exhaust gases, which would otherwise be wasted. By exploiting the energy contained in the exhaust gases, the impeller 19 of the pump can also be moved without subtracting power from the internal combustion engine. In addition, the valve and the control circuit acting on the exhaust gases directed towards the turbine enable circulating the cooling liquid in the engine only when it is effectively necessary to cool the engine.

The device 11 shown in Figures 8 to 11 can also provide some additional benefits.

Firstly, the device 11 can be positioned at any desired point of the vehicle. It is, therefore, not necessary to position the pump circulating the cooling liquid near the engine cylinder block. By using appropriate connecting pipes to connect the inlet conduit 26 to the radiator, the outlet conduit 27 to the engine components to be cooled and the conduit 20 to the holes from which the exhaust gases exit, the device 11 can be positioned in any desired position. This ensures greater design flexibility because the designer is no longer obliged to fix the pump which circulates the cooling liquid to the cylinder block.

In addition, all the components of the device 11 can be easily removed in order to be repaired or replaced. In particular, the stator body 15 can be removed, after which the impeller 19 of the pump can be disassembled from the shaft 16 simply by unscrewing it. At this point, the sealing element 18 can be removed and the bearing 17 slid out when needing replacement.

The working life of the device 11 is thus rendered completely independent of the working life of the bearing 17. The impeller 13 of the turbine can also be easily disassembled from the shaft 16, should this be necessary .

In an embodiment that is not illustrated, instead of the bearing 17 any other support element can be used, the support element being suitable for supporting the shaft 16 during rotation. For example, a self-lubricating bushing can be used instead of the bearing 17.

Finally, instead of the turbine and the corresponding impeller 13 it is possible to use any other driving element that can be moved by the exhaust gases produced by the internal combustion engine, the driving element being capable of being connected to the pump to rotate the impeller of the pump.

For example, instead of the turbine and its impeller 13 a blade or any other rotatable element could be used.