GB2486419A

GB2486419A - Engine cooling circuit with turbocharger cooling

Info

Publication number: GB2486419A
Application number: GB201021075A
Authority: GB
Inventors: Luca Borgia
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2010-12-13
Filing date: 2010-12-13
Publication date: 2012-06-20
Also published as: GB201021075D0

Abstract

A cooling circuit 11 for an internal combustion engine 10 equipped with a turbocharger 30 is disclosed. The cooling circuit is provided with a cooling fluid pump 24 for the circulation of a cooling fluid in the circuit and a heat exchanger 20, such as a countercurrent heat exchanger, directly connected to the turbocharger. The heat exchanger is arranged to receive a cooling fluid exiting from the turbocharger and a cooling fluid coming from the engine, allowing a heat exchange between the two fluids. A degassing line 32 may be provided exiting from the heat exchanger and leading to a surge tank 18. Preferably, the heat exchanger has a dimension suitable to cool down the fluid exiting from the turbocharger to a temperature that is lower than the melting temperature of the degassing line or of the surge tank. The cooling fluid coming from the engine may reach the heat exchanger by means of a line 34 bypassing an EGR cooler 16.

Description

COOLING CIRCUIT FOR AN INTERNAL CCMBUSTION ENGINE EQUIPPED WITH A

TURBCCHARGER

TECHNICAL FIELD

The present disclosure relates to a cooling circuit for an internal cortustion engine equipped with a turbocharger.

BAKOUND

Due to current engine technology more and more powerful engines are produced. One of the causes of this phenomenon is the use of riulti-stage cooled TurboChargers (TO) which require huge room availability for their packaging into the engine vane.

A serious disadvantage that arises from this situation is that, since the layout of the turbochargers is usually on top of the engine, especially for multi-stage versions in which generally at least the lower pressure stage of the turbocharger is on the top side of the engine, it becomes difficult to guarantee the effective cooling of the turbocharger bearing housing, also considering the closely packed configuration of these engines.

Also, during operation of the cooling system, gas pockets may occur in the system that are degassed continuously by means of a degassing line which also release a small annunt of coolant into a reservoir or surge tank.

However, the fact that at least the lower pressure stage of the turbocharger is on the top side of the engine requires to have a direct connection to the surge tank to allow the degassing, but with this solution it has been found that there is a high possibility to melt the surge tank due to too high temperatures in the degassing line.

Moreover, if a deviation is allowed in the cooling circuit to connect it to the surge tank, a big quantity of heat is lost in the degassing line, leading to a loss of thermal efficiency in the engine.

A similar issue arises when a siphon is considered for the routing of the turbocharger pipes from the top of the engine towards the lower side; in any case degassing is still needed and vapors that are too hot can still reach the surge tank.

An object of an ertodiment of the invention disclosed is to achieve a greater degree of freedom in the turbocharger and engine layout design, minimizing architeoture roadblocks.

Another object of the present disclosure is to give the engine designers mote options to design the turbocharger pipes touting.

A further object of an embcdiment of the invention is to increase thermal efficiency of the engine as a whole.

These and other objects are achieved by a cooling circuit for an internal conibustion engine equipped with a turbocharger and by an engine having the features recited in the independent claims.

The dependent claims delineate preferred and/or especially advantageous aspects. sunRy

An embodiment of the invention provides for a cooling circuit for an internal combustion engine equipped with a turbocharger, the cooling circuit being provided with a cooling fluid pump for the circulation of a cooling fluid in the circuit and an heat exchanger directly connected to the turbocharger and arranged to receive a cooling fluid exiting from the turbocharger and a cooling fluid coming from the engine allowing an heat exchange between the two fluids.

An advantage of this embodiment is that it allows to recover a certain fraction of heat in the fluid exiting from the turbocharger and send it to the inlet of the cooling fluid pump having 002 emission reduction advantages.

Since the terrperature of the fluid exiting the turbine is generally higher than the temperature of the fluid exiting the engine, it is possible to use such difference to recover some heat.

According to a further embodiment of the invention, a degassing line exiting from the heat exchanger and leading to a surge tank is provided in the cooling circuit.

An advantage of this embodiment is that it configures an optimal point to derive a degassing line.

According to a further embodiment of the invention, the heat exchanger has a dimension suitable to cool down the fluid exiting from the turbocharger to a temperature that is lower than the melting temperature of the degas sing line or of the surge tank.

An advantage of this embodiment is that it allows to send to the surge tank a degassing line carrying a fluid having a temperature that avoids the possibility of surge tank melting.

According to a further embodiment of the invention, the cooling fluid coming fran the engine reaches the heat exchanger by means of a line bypassing an EGR cooler.

An advantage of this erhbodiment is that the heat exchanger can be integrated in an existing portion of the cooling circuit.

Still another embodiment of the invention provides for the fact that the heat exchanger is connected to a cooling fluid purrp inlet by means of a recovery line for recovering the cooling fluid coming from the engine and exiting the heat exchanger.

An advantage of this embodiment is that it leads to higher engine thermal efficiency having benefits on 002 on emission reduction.

According to still another embodiment of the invention, the heat exchanger operates is a countercurrent heat exchanger.

An advantage of this embodiment is that it allows a high heat transfer efficiency.

BRIEF DESRIPflfl OF THE DRAWINGS The various embodiments will now be described, by way of example, with reference to the acconanying drawing, in which: Figure 1 is a schematic representation of an internal combustion engine equipped with a turbocharger and a with cooling circuit according to an embodiment of the invention.

DETMLED DESCRtPTI OF THE DRAWINGS Preferred embodiments will now be described with reference to the enclosed drawing.

S In fig. 1 a cooling circuit 11 for an internal combustion engine 10 is represented.

The cooling circuit 11 is provided with a cooling fluid pump 24, acted upon by a thermostat 26, the pump 24 being used to send a cooling fluid, e.g. water with an antifreeze component, to the engine block, where it makes its way through passages in the engine 10 around the cylinders.

The cooling fluid exiting from the engine 10 may be used in connection with an oil heat exchanger 12 for heating the lubricating oil temperature and in connection with a cab heater 14.

Also, the cooling fluid exiting from the engine 10 may be used in connection with an Exhaust Gas Recirculation (EGR) cooler 16 in which the heat of the recirculated exhaust gas is partially transferred to the cooling fluid before the exhaust gas reach the intake manifold.

After passing through the EGR cooler 16, the fluid is sent to an electric pump 24 and back to the thermostat 26.

If the temperature of the cooling fluid exceeds a predefined threshold, the thermostat 26 is operated and the fluid, before reaching the pump 24 is circulated through a radiator 28.

The engine 10 is also equipped with a turbocharger 30.

According to an embodiment of the invention, an heat exchanger 20 is provided that is associated to the turbocharger 30.

The heat exchanger 20 is directly connected to the turbocharger 30 and arranged to receive a cooling fluid exiting from the turbocharger 30.

Namely, the cooling fluid exiting from the pump 24 is also circulated through the turbocharger 30 where it absorbs heat, cooling in particular the turbocharger bearing housing and then reaching a temperature To.

The fluid exiting the turbocharger 30 at temperature T0 is then sent through the heat exchanger 20 where a second flow of fluid coming from a by-pass line 34 and that is at a temperature T2 is circulated in countercurrent.

By effect of the heat exchanger 20, the fluid at temperature T0 is cooled at temperature T1 and the fluid at temperature T2 is warmed and reaches temperature T3.

The fluid at temperature T3 is then sent back to the pump 24 by a cooling fluid recovery line 35 and then through the thermostat 26 and is at a temperature that is higher than the temperature normally obtainable in the by-pass line 34, leading to a recover of heat lost in engine with benefits in terms of 002 emission reduction.

Also from the heat exchanger 20, a degassing line 32 is connected to a surge tank 18 that is used for the release of entrapped gas into the cooling fluid.

The degassed fluid is then recirculated back towards the by-pass line 34 and then to the heat exchanger 20.

By virtue of the above described cooling circuit 11, the fluid exiting from the turbocharger 30 can be cooled down to a temperature T1 that is sufficiently low in order to avoid the melting of the degassing line or of the surge tank 18.

At the same time a portion of heat is recovered to be sent to the cooling fluid pump 24 inlet.

Since degassing is performed spilling colder fluid from the top side of the heat exchanger 20 towards the surge tank 18, the use of a siphon can be allowed if needed.

The turbocharger 30 can be a single-stage turbocharger or a multi-stage turbocharger, in particular the lower pressure stage of a multi-stage turbocharger.

Vthile at least one exemplary embodiment has been presented in the foregoing surrinary 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 examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing surrrnary and detailed description 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 nay be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NtI4BERS engine 11 cooling circuit 12 oil cooler 14 cab heater 16 EGR cooler 18 surge tank heat exchanger 22 electric pump 24 water pump 26 thermostat 28 radiator turbocharger 32 degassing line 34 by-pass line cooling fluid recovery line T0 temperature of fluid exiting the turbocharger T1 temperature of fluid from the turbocharger exiting the heat exchanger T2 temperature of fluid from the engine T3 temperature of fluid from the engine exiting the heat exchanger cians

Claims

1. Cooling circuit (11) for an internal combustion engine (10) equipped with a turbocharger (30), the cooling circuit (11) being provided with a cooling fluid pump (24) for the circulation of a cooling fluid in the circuit (11) and an heat exchanger (20) directly connected to the turbocharger (30) and arranged to receive a cooling fluid exiting from the turbocharger (30) and a cooling fluid coming from the engine (10) allowing an heat exchange between the two fluids.

2. Cooling circuit (11) according to claim 1, in which a degassing line (32) exiting from the heat exchanger (20) and leading to a surge tank (18) is provided.

3. Cooling circuit (11) according to claim 2, in which the heat exchanger (20) has a dimension suitable to cool down the fluid exiting from the turbocharger (30) to a temperature (Ti) that is lower than the melting temperature of the degassing line (32) or of the surge tank (18).

4. Cooling circuit (11) according to claim 1, in which the cooling fluid coming from the engine (10) reaches the heat exchanger (20) by means of a line (34) bypassing an EGR cooler (16).

5. Cooling circuit (11) according to claim 1, in which the heat exchanger (20) is connected to a cooling fluid pump (24) inlet by means of a recovery line (35) for recovering the cooling fluid coming from the engine (10) and exiting the heat exchanger (20).

6. Cooling circuit (11) according to claim 1, in which the heat exchanger (20) is a countercurrent heat exchanger (20).