GB2483271A

GB2483271A - Oil heating and charge cooling of a turbocharged internal combustion engine

Info

Publication number: GB2483271A
Application number: GB1014574.6A
Authority: GB
Inventors: Fiorello Losano
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2010-09-02
Filing date: 2010-09-02
Publication date: 2012-03-07
Anticipated expiration: 2030-09-02
Also published as: GB201014574D0; GB2483271B

Abstract

A turbocharged internal comÂbustion engine 10 comprising a lubricating circuit 60, an intake line 20, a compressor 42 located in the intake line 20, and a heat exchanger 70 arranged for exchanging heat between a lubricatÂing fluid flowing in the lubricating circuit 60 and a charge air flowing in the intake line 20 downstream of the compressor 42. The engine may also comprise an intercooler or charge air cooler 50 positioned downstream of the compressor 42 and in series or parallel with the heat exchanger 70, and having a bypass conduit and/or hydraulic apparatus 80 for channelling the charge air towards the air cooler 50 or heat exchanger 70. The invention is intended to quicken the warm-up of the lubricating fluid, achieving a better oil viscosity, and to enhance the cooling of the charge air and improve the engineâ s volumetric efficiency.

Description

s TUPBOCHARGED INTERNAL CCt4BUSTION E2GINE TECHNICAL FlEW The present invention relates to a turbocharged internal combustion engine, typically a turbocharged internal combustion engine of a mo-tar vehicle.

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An internal combustion engine is generally provided with an intake manifold, an exhaust manifold, an intake line for conveying air from the environment into the intake manifold, and an exhaust line for conveying the exhaust gas frau the exhaust manifold to the environ-ment.

A turbocharged internal combustion engine is further equipped with a turbocharger comprising a compressor, which is located in the intake line to charge the air into the intake manifold at increased pres-sure, and a turbine, which is located in the exhaust line to drive the compressor.

A side effect of the turbocharger is that the compression of the air causes also an increase of the air temperature, thereby deteriorating the volumetric efficiency, worsening the combustion process and the performance of the internal combustion engine.

For this reason, any turbocharged internal combustion engine conven-tionally comprises a charge air cooler, also referred as intercooler, which is located in the intake line downstream of the corrpressor, in order to cool the charge air to an appropriate low temperature.

As a matter of fact, the charge air cooler *is an heat exchanger, in which the heat of the charge air is transferred directly to the envi-ronment (air to air heat exchanger), or to an intermediate coolant, typically a mixture of water and antifreeze, which flows in a dedi-cated circuit provided with a pump and a radiator (air to liquid heat exchanger).

However, the charge air is not the only engine fluid whose tempera-ture affects the performance of the turbocharged internal combustion engine.

Another engine fluid having this effect is the lubricating fluid (oil) that flows in the lubricating circuit of the turbocharged in-ternal combustion engine, for lubricating and cooling the rotating or sliding components of the latter.

Indeed, the effectiveness of the lubrication depends on the viscosity of the lubricating fluid, which in turn is strongly affected by its temperature.

In particular, when the lubricating fluid is cold, such as at the start of the engine, it has a great viscosity that increases the en- gine frictions, thereby increasing the fuel consumption and the pol-luting emissions.

In view of the above, it is an object of an embodiment of the present invention to quicken the warm-up of the lubricating fluid in the lu- bricating circuit, so as to achieve a better oil viscosity that al-lows to solve, or at least to positively reduce, the above mentioned drawbacks.

Another object is to enhance the cooling of the charge air, at full load conditions of the engine, in order to further increase the volu-metric efficiency and so the engine perfonnance.

These and/or other objects are attained by the characteristics of the embodiments of the invention as reported in independent claims. The dependent claims recite preferred and/or especially advantageous fea-tures of the embodiments of the invention. sBx

An embodiment of the invention provides a turbocharged internal com-bustion engine, which comprises a lubricating circuit, an intake line, a compressor located in the intake line, and an heat exchanger arranged for exchanging heat between a lubricating fluid flowing in the lubricating circuit and a charge air flowing in the intake line downstream of the compressor.

This solution advantageously allows to use the heat of the charge air downstream of the compressor (which can reach a temperature of 150- 160°C) to increase the temperature of the lubricating fluid, so that the latter is warmed up faster.

At the same time, this solution advantageously allows to enhance the cooling of the charge air and the related engine volumetric efficien-cy.

According to an aspect of the invention, the turbocharged internal combustion engine additionally comprises a charge air cooler, of the conventional kind, which is arranged for cooling the charge air f low-ing in the intake line downstream of the compressor.

In this way, the charge air cooler advantageously guarantees an ef-fective cooling of the charge air, also when the lubricating fluid is warmed up.

According to an embodiment of the invention, the charge air cooler is located in the intake line, while the heat exchanger is located in a bypass conduit connecting a first point of the intake line, which is located between the ccmpressor and the charge air cooler, to a second point of the intake line, which is located downstream of the charge air cooler.

As a matter of fact, this embodiment of the invention provides that the heat exchanger and the charge air cooler are connected in paral-lel, so that it is advantageously possible to bypass the charge air cooler during the warm up of the lubricating fluid, thereby quicken-ing this warm up and preventing a charge air overcooling.

It is also advantageously possible to bypass the heat exchanger once the lubricating fluid is warmed up, so that the heat exchanger can be completely deactivated, thereby reducing the mechanical energy neces-sary to drive the pump of the lubricating circuit.

In order to do so, an aspect of this embodiment provides for the tur- bocharged internal combustion engine to comprise an hydraulic appara-tus, namely one or nore hydraulic valves, arranged for channeling the charge air towards the charge air cooler and alternatively towards the heat exchanger.

According to an alternative embodiment of the invention, both the charge air cooler and the heat exchanger can be located in the intake line downstream of the compressor, so as to be mutually connected in series.

By means of this architecture, the charge air can be subjected to two cooling stages, thereby reaching a lower temperature that achieves benefits in terms of volumetric efficiency, fuel consumption and per-formance of the engine.

Moreover, the use of two cooling stages advantageously allows to di- mensioning the charge air cooler smaller than usual, saving space in-to the engine compartment of the vehicle and gaining benefits in tenis of frontal area and aerodynamic drag of the vehicle, leading to further lower fuel consumption.

According to an aspect of this embodiment, the turbccharged internal combustion engine comprises a bypass conduit connecting a first point of the intake line, which is located between the charge air cooler and the heat exchanger, to a second point of the intake line, which is located at the opposite side of the charge air cooler with respect of the first point, such that the bypass conduit bypasses the charge air cooler.

In this way, it is advantageously possible to bypass the charge air cooler during the warm up of the lubricating fluid, thereby quicken-ing this warm up and preventing a charge air overcooling.

In order to do so, an aspect of this embodiment provides for the tur- bocharged internal combustion engine to comprise an hydraulic appara-tus, which is arranged for channeling the charge air towards the charge air cooler and alternatively towards the bypass conduit.

According to another embodiment of the invention, the turbocharged internal combustion engine comprises a further hydraulic apparatus, which is arranged for allowing and alternatively preventing the lu-bricating fluid to flow through the heat exchanger.

This solution has the advantage of allowing to deactivate the heat exchanger, once the lubricating fluid is warmed up, in order to re-duce the energy consumption of the lubricating fluid pump and thus the fuel consumption.

Another embodiment of the invention provides a method for operating a turbocharged internal combustion engine, which comprises the step of channeling a lubricating fluid, which flows in a lubricating circuit of the engine, and a charge air, which flows in an intake line of the engine downstream of a compressor, to flow through a same heat ex-changer so as to allow an heat exchange between them.

As explained above, this solution advantageously allows to quicken the warm up of the lubricating fluid and to enhance the cooling of the charge air.

According to an aspect of the invention, the method comprises the further steps of: -monitoring a value of a parameter indicative of an engine tem-perature, and -preventing the charge air to flow through the heat exchanger, if the value of the parameter exceeds a threshold value of this parameter.

This aspect has the advantage of preventing an overheating of the lu-bricating fluid once the letter is warmed up.

According to still another aspect of the invention, the method com-prises the further step of preventing also the lubricating oil to flow through the heat exchanger, if the value of the parameter ex-ceeds the threshold value.

In this way, it is advantageously possible to reduce the energy spent by the pump of the lubricating circuit for circulating the lubricat-ing fluid, getting better fuel economy.

An eritodiment of the invention provides for the method to comprise an additional step of channeling the charge air to flow also through a charge air cooler.

This solution advantageously allows to achieve an adequate reduction of the charge air temperature, even when the lubricating fluid is al-ready warmed up.

According to an aspect of this embodiment, the method comprises the step of preventing the charge air to flow through the charge air coo-ler, if the value of the above mentioned parameter indicative of the engine temperature falls below the threshold value.

This aspect of the invention has the advantage of preventing an over-cooling of the charge air.

According to still another embodiment of the invention, the method can be carried out with the help of a computer program comprising a program-code for carrying out all the steps of the method described above, and in the form of a computer program product comprising the computer program.

The computer program product can be embodied as a control apparatus for a turbocharged internal combustion engine, comprising an engine control unit (ECU), a data carrier associated to the engine control unit, and the computer program stored in the data carrier, so that, when the ECU executes the computer program, all the steps of the me-thod described above are carried out.

The method can be also embodied as an electromagnetic signal, said signal being modulated to carry a sequence of data bits which represent a computer program to carry out all steps of the method.

BRIET DESCRIPflC*T OF TI DRAWfl4GS The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: figure 1 schematically illustrates a turbocharged internal combustion engine according to a first embodiment of the invention; figure 2 is a flowchart schematically representing a method for oper-ating the turbocharged internal combustion engine of figure 1; figure 3 schematically illustrates a turbocharged internal combustion engine according to a second embodiment of the invention; figure 4 is a flowchart schematically representing a method for oper-ating the turbocharged internal combustion engine of figure 3.

DEThIL DEScRXPTIQ4 Figure 1 shows an turbocharged internal combustion engine 10 of a mo-tar vehicle, which can be a Diesel engine as well as a spark ignited engine.

The turbocharged internal combustion engine 10 comprises an intake line 20, for conveying air into an intake manifold 21 connected with the engine cylinders, and an exhaust line 30, for discharging exhaust gas from an exhaust manifold 31 connected to the same engine cylind-ers.

The turbocharged internal combustion engine 10 is further equipped with a turbocharger 40, which comprises a turbine 41 and a compressor 42 mutually connected by a shaft 43.

The compressor 42 is located in the intake line 20 to charge the air into the intake manifold 21 at increased pressure, while the turbine 41 is located in the exhaust line 30 to rotate under the action of the exhaust gas, and thus to drive the compressor 42 by means of the connecting shaft 43.

A conventional charge air cooler 50 is located in the intake line 20 downstream of the compressor 42, with respect to the direction of the air flow, in order to cool the charge air to an appropriate low tem- perature suitable for enhancing the combustion process and the per-fonnance of the engine 10.

In the present embodiment, the charge air cooler 50 is an air to liq- uid heat exchanger, in which the heat of the charge air is trans-ferred to an intermediate coolant, typically a mixture of water and antifreeze, which flows in a dedicated circuit 51 provided with a pump 52 and a radiator 53.

Eventually, the charge air cooler 50 can be replaced by an air to air heat exchanger.

The turbocharged internal combustion engine 10 is further equipped with a conventional lubricating circuit 60, in which a lubricating oil is circulated so as to cool and lubricate the rotating or sliding components of the engine 10.

As a matter of fact, the lubricating circuit schematically comprises an oil pump 61 driven by the engine 10, which draws lubricating oil from an engine oil sump, and which delivers this lubricating oil un- der pressure through an oil gallery in the cylinder block of the en-gine 10.

The oil gallery is connected via respective pipes to a plurality of exit holes for lubricating crankshaft bearings (main bearings and big-end bearings), camshaft bearings operating the valves, tappets, and the like.

A radiator 62 is usually located in the lubricating circuit 60 for cooling the lubricating oil, thereby maintain its temperature below a predetermined value of about 110°C.

According to an aspect of the invention, the turbocharged internal combustion engine 10 further comprises an auxiliary heat exchanger 70, which is arranged for transferring heat from the charge air f low- ing in the intake line 20 downstream of the compressor 42 to the lu-bricating oil flowing in the lubricating circuit 60, keeping them physically separated.

In the embodiment shown in figure 1, the heat exchanger 70 is located in a bypass conduit 22, which branches from a first point 23 of the intake line 20 downstream of the compressor 42, and which leads to a second point 24 of the intake line 20 downstream of the charge air cooler 50.

In this way, the heat exchanger 70 and the charge air cooler 50 are connected in parallel.

An hydraulic apparatus 80 is arranged for channeling the charge air towards the charge air cooler 50 and alternatively towards the heat exchanger 70 via the bypass conduit 22.

The hydraulic apparatus 80 coniprises two controlled valves, including a first valve 81 located in the intake line 20, between the point 23 and the charge air cooler 50, and a second valve 82 located in the bypass conduit 22, between the point 23 and the heat exchanger 70.

Alternatively, the valves 81 and 82 can be replaced by a single valve, such as for example by a three way valve located in the point 23.

The heat exchanger 70 is further hydraulically located in the lubri-cating circuit 60.

The lubricating circuit 60 comprises a bypass conduit 63, which branches from a first point 64 between the pump 61 and the heat ex-changer 70, and which leads to a second point 65 downstream of the heat exchanger 70.

P1n hydraulic apparatus 90 is arranged for channeling the lubricating oil towards the heat exchanger 70 and alternatively towards the by-pass conduit 63.

This hydraulic apparatus 90 comprises an controlled valve 91 located in the bypass conduit 63, and another controlled valve 92 located in the lubricating circuit 60 between the point 64 and the heat exchang-er 70.

Also in this case, the valves 91 and 92 can be replaced by a single valve, such as for example by a three way valve located in the point 64.

The valves 81, 82, 91 and 92 are connected to a control apparatus 100 comprising an engine control unit (ECU) 101, which is configured for controlling their operation according to the strategy schematically represented in the flowchart of figure 2.

This control strategy firstly provides for monitoring a value T of a parameter indicative of the temperature of the turbocharged internal combustion engine 10.

In the present example, this parameter is the temperature of the lu-bricating oil.

Alternatively, the parameter could be the temperature of the exhaust gas, the temperature of the engine coolant (water), or an engine met-al temperature, that is the temperature of a metallic component of the engine, such as for example the cylinder head or the cylinder block.

The engine temperature parameter can be monitored by means of a dedi- cated sensor connected to the ECU 101 and/or with the aid of an esti-roation.

As long as the value T is below a predetermined threshold value Th of the lubricating oil temperature, namely during a warm up stage of the engine 10, the strategy provides for preventing the charge air to flow through the charge air cooler 50, but for allowing both the charge air and the lubricating oil to flow through the heat exchanger 70.

As a matter of fact, this arrangement can be achieved by the ECU 101 through the steps of closing the valves 81 and 91, and of opening the valves 82 and 92.

In this way, the heat exchanger 70 allows a transfer of heat from the charged air flowing downstream the compressor 42 (whose temperature can reach about 150-160°C) to the lubricating oil flowing in the lu-bricating circuit 60.

As a consequence, while the charged air is cooled to enhance the com-bustion process and the performance of the engine 10, the lubricating oil is heated to quicken its warm up, thereby reducing the engine frictions and the fuel consumption.

1⁄2hen the value T of the lubricating oil temperature exceeds the pre-determined threshold value Th, namely when the lubricating oil is properly warmed up, the strategy provides for allowing the charge air to flow through the charge air cooler 50, and for preventing both the charge air and the lubricating oil to flow through the heat exchanger 70.

As a matter of fact, this second condition can be achieved by the ECU 101 through the steps of opening the valves 81 and 91, and of closing the valves 82 and 92.

In this way, the charge air is cooled inside the charge air cooler 50 in a conventional mode, while the mechanical work requested to the pump 61 for delivering the lubricating oil in the lubricating circuit is advantageously reduced, thereby reducing also the fuel consump-tion.

Figure 3 shows an turbocharged internal combustion engine 10 accord-ing to a second embodiment of the invention, wherein the features in common with the first embodiment are indicated with the same refer-ence numbers.

As a matter of fact, the turbocharged internal combustion engine 10 of this second embodiment differs from the preceding one essentially in that both the heat exchanger 70 and the charge air cooler 50 are located in the intake line 20 downstream of the compressor 42.

More precisely, the heat exchanger 70 is located upstream of the charge air cooler 50.

In this way, the heat exchanger 70 and the charge air cooler 50 are connected in series.

The turbocharged internal combustion engine 10 further comprises a bypass conduit 25, which branches from a first point 26 of the intake line 20 between the heat exchanger 70 and the charge air cooler 50, and which leads to a second point 27 of the intake line 20 at the op-posite side of the charge air cooler 50, namely downstream of the latter.

As a consequence, the charge air is forced to always flow trough the heat exchanger 70.

An hydraulic apparatus 110 is arranged for channeling the charge air towards the charge air cooler 50 and alternatively towards the bypass conduit 25.

The hydraulic apparatus 110 comprises two controlled valves, includ-ing a first valve 111 located in the intake line 20, between the point 26 and the charge air cooler 50, and a second valve 112 located in the bypass conduit 25.

Alternatively, the valves 111 and 112 could be replaced by a single valve, for instance a three way valve located in the point 26 of the intake line 20.

The valves 91, 92, 111 and 112 are connected to the engine control unit (ECU) 101, which is configured for controlling their operation according to the strategy schematically represented by the flowchart shown in figure 4.

As before, this control strategy provides for monitoring the value T of a parameter indicative of the temperature of the turbocharged in- ternal combustion engine 10, in this case the temperature of the lu-bricating oil.

As long as the value T is below the predetermined threshold value Th, namely during a warm up stage of the engine 10, the strategy provides for preventing the charge air to flow through the charge air cooler 50, and for allowing the lubricating oil to flow through the heat ex-changer 70.

As a matter of fact, this arrangement can be achieved by the ECU 101 through the steps of closing the valves 111 and 91, and of opening the valves 112 and 92.

In this way, the heat exchanger 70 allows a transfer of heat from the charged air flowing downstream the compressor 42 to the lubricating oil flowing in the lubricating circuit 60, so that the charged air is cooled while the lubricating oil is heated.

When the value T of the lubricating oil temperature exceeds the pre-determined threshold value Th, namely when the lubricating oil is warmed up, the strategy provides for allowing the charge air to flow also through the charge air cooler 50.

As a matter of fact, this second condition can be achieved by the ECU 101 through the steps of opening the valve 111 and of closing the valve 112.

Meanwhile, the valves 91 and 92 are kept respectively closed and open, so that the lubricating oil continues to flow through the heat exchanger 70.

In this way, the charge air is subjected to two cooling stages, the-reby reaching a lower temperature that causes benefits in terms of volumetric efficiency, fuel consumption and performance of the en-gine.

Moreover, the use of two cooling stages advantageously allows to di-mensioning the charge air cooler 50 smaller than usual, saving space into the engine compartment of the vehicle.

According to an aspect of the invention, each of the control strate-gies disclosed above, for the first and the second embodiment, can be managed with the help of a computer program comprising a program-code for carrying out all the steps described above.

The computer program is stored in a data carrier 102 associated to the ECU 101.

In this way, when the ECU 101 executes the computer program, all the steps of the errbodiments of the method described above are carried out.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only exam- ples, and are not intended to limit the scope, applicability, or con- figuration in any way. Rather, the foregoing summary and detailed de-scription will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and ar-rangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. aam

Claims

1. Turbocharged internal combustion engine (10) comprising a lubri- cating circuit (60), an intake line (20), a compressor (42) lo- cated in the intake line (20), and an heat exchanger (70) ar-ranged for exchanging heat between a lubricating fluid flowing in the lubricating circuit (60) and a charge air flowing in the in-take line (20) downstream of the compressor (42).

2. Turbocharged internal combustion engine (10) according to claim 1, additionally comprising a charge air cooler (50) arranged for cooling the charge air flowing in the intake line (20) downstream of the compressor (42).

3. Turbocharged internal combustion engine (10) according to claim 2, wherein the charge air cooler (50) is located in the intake line (20), and the heat exchanger (70) is located in a bypass conduit (22) connecting a first point (23) of the intake line (20), which is located between the compressor (42) and the charge air cooler (50), to a second point (24) of the intake line (20), which is located downstream of the charge air cooler (50).

4. Turbocharged internal combustion engine (10) according to claim 3, comprising an hydraulic apparatus (80) for channeling the charge air towards the charge air cooler (50) and alternatively towards the heat exchanger (70).

5. Turbocharged internal combustion engine (10) according to claim 2, wherein both the charge air cooler (50) and the heat exchanger (70) are located in the intake line (20), so as to be mutually connected in series.

6. Turbocharged internal combustion engine (10) according to claim 5, comprising a bypass conduit (25) connecting a first point (26) of the intake line (20), which is located between the charge air cooler (50) and the heat exchanger, to a second point (27) of the intake line (20), such that the bypass conduit (25) bypasses the charge air cooler (50).

7. Turbocharged internal combustion engine (10) according to claim 6, comprising an hydraulic apparatus (110) for channeling the charge air towards the charge air cooler (50) and alternatively towards the bypass conduit (25).

8. Turbocharged internal combustion engine (10) according to any of the preceding claims, comprising an hydraulic apparatus (90) for allowing and alternatively preventing the lubricating fluid to flow through the heat exchanger (70).

9. Method for operating a turbocharged internal combustion engine (10), comprising the step of channeling a lubricating fluid, which flows in a lubricating circuit (60) of the engine (10), and a charge air, which flows in an intake line (20) of the engine (10) downstream of a compressor (42), to flow through a same heat exchanger (70) so as to allow an heat exchange between them.

10. Method according to claim 9, comprising the further steps of: -monitoring a value (T) of a parameter indicative of an en-gine temperature, and -preventing the charge air to flow through the heat exchanger (70), if the value (T) of the parameter exceeds a threshold value (Th) of this parameter.

11. Method according to claim 10, comprising the further step of pre- venting also the lubricating oil to flow through the heat ex-changer, if the value (T) of the parameter exceeds the threshold value (Th).

12. Method according to claim 9, 10 or 11, comprising the additional step of channeling the charge air to flow also through a charge air cooler (50).

13. Method according to claim 10 and 12, comprising the step of pre-venting the charge air to flow through the charge air cooler (50), if the value (T) of the parameter indicative of the engine temperature falls below the threshold value (Th).

14. Computer program comprising a computer-code for carrying out a method according to any of the claims from 9 to 13.

15. Control apparatus (100) for an turbocharged internal combustion engine (10), comprising an engine control unit (101), a data car-rier (102) associated to the engine control unit (101), and a computer program according to claim 14 stored in the data carrier (102).