GB2507343A

GB2507343A - A heating apparatus for an internal combustion engine

Info

Publication number: GB2507343A
Application number: GB1219392.6A
Authority: GB
Inventors: Fiorello Losano; Salvatore Mafrici
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2012-10-29
Filing date: 2012-10-29
Publication date: 2014-04-30
Anticipated expiration: 2032-10-29
Also published as: GB201219392D0; GB2507343B

Abstract

The invention provides a heating apparatus 505 for an internal combustion engine 110 equipped with an engine oil circuit 525 which has an engine oil heat exchanger 520. The engine has a main pump 590 for circulating an engine coolant in a main coolant circuit 517, and an auxiliary pump 500 for circulating the coolant in an auxiliary coolant circuit 515 and which includes the engine oil heat exchanger. The main pump and the auxiliary pump are electrically connected to an Electronic Control Unit (ECU) 450 which can monitor an engine oil temperature in the engine oil circuit. The ECU can also energize the auxiliary pump if the monitored engine oil temperature value is lower than a predetermined threshold value. The oil temperature may be measured by a temperature sensor 385 connected to the ECU, and the ECU may both activate and deactivate the main pump.

Description

OIL HEATING APPARATUS FOR AN INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD

The present disclosure relates to an oil heating apparatus for an internal combustion engine.

BACKGROUND

Traditional internal combustion engines have an engine block defining at least one cylinder having a piston coupled to rotate a crankshaft. A cylinder head cooperates with the piston to define a combustion chamber.

Fuel combustion in the combustion chamber generates a significant amount of heat and a cooling circuit is generally provided in order to manage the engine temperature during the various operating phases, allowing for a correct operation of the engine and avoiding possible damages to the engine components due to excessive temperature.

An engine coolant is circulated in the cooling circuit and is sent by a coolant pump to the engine block and circulates therein exiting from a cylinder head1 since the engine block and the cylinder head are equipped with a plurality of passageways cast or mach-med therein to allow the coolant fluid flow.

The coolant is then sent to a radiator which has the function of transferring heat absorbed by the coolant to the ambient air. The coolant may be a mixture of water and of an antifreeze component In some embodiments, a switchable water pump, circulates coolant between the engine and the radiator when the switchable water pump is engaged and a thermostat is open. The thermostat is selectively opened to facilitate coolant flow between the engine and the radiator. For example, the thermostat may be opened when the temperature of the coolant within the engine exceeds a predetermined opening temperature.

The switchable water pump is driven by the engine, for example by rotation of the crankshaft. The switchable water pump may be selectively engaged or disengaged from the engine. For example, the switchable water Øump may be selectively disengaged to disable the circulation of coolant throughout the engine during engine start up for achieving a faster warm up.

A lubricant, such as oil, is generally provided to lubricate the engine, the lubricant circulating in an oil circuit.

In the oil circuit, an oil pump draws oil from a crankcase sump and distributes it to passages leading into the engine block. From there, the oil goes to crankshaft bearings, camshaft bearings, valve shafts and other moving metal parts that require lubrication to help avoid excess friction and heat buildup.

An oil cooler is often provided in the oil circuit to cool off the oil when an excessive oil temperature threshold is reached, avoiding excessive temperature thereof. Below such temperature threshold the oil flow may be directed through an oil cooler by-pass line to bypass the oil cooler.

Oil temperature deeply influences engine friction during warm up: an higher oil temperature has beneficial effects in reducing engine friction.

An object of an embodiment disclosed is improve the performance of the engine, especially at start up.

A further object of an embodiment of the invention is to obtain a thermal management of the engine oil that may improve fuel economy.

Still another object of the present disclosure is to meet these goals by means of a simple, rational and almost inexpensive solution.

These objects are achieved by an oil heating apparatus for an intemal combustion engine, by an internal combustion engine and by a method of operation thereof according to the claims.

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

SUMMARY

An embodiment of the invention provides an oil heating apparatus for heating oil in an internal combustion engine equipped with an oil circuit having an oil heat exchanger, the apparatus comprising a main pump for circulating an engine coolant in a main coolant circuit and an auxiliary pump for circulating the coolant in an auxiliary coolant circuit, the auxiliary coolant circuit comprising the oil heat exchanger, wherein the main pump and the auxiliary pump are electrically connected to an Electronic Control Unit, which is configured for monitoring an engine oil temperature in the oil circuit and for energizing the auxiliary pump if the monitored oil temperature value is lower than a predetermined threshold value thereof.

Thanks to this solution a quicker warming up of engine oil, especially at engine start up, is achieved. This may be beneficial in real life condition, particularly in connection with cold weather temperatures.

For example, in some automotive systems, an engine oil temperature of 40 °C instead of 30 DC may reduce engine friction at 2000 rpm of approximately 20%, a phenomenon that may correspond to approximately 4% in fuel economy.

Furthermore, with this embodiment, it is not necessary to equip the oil circuit with an oil cooler by-pass as in conventional applications.

According to a further embodiment of the invention, the auxiliary pump is an electric pump.

An advantage of this embodiment is that the auxiliary pump may be autonomously energized by a command of the Electronic Control Unit according to the needs.

According to still another embodiment of the invention, the Electronic Control Unit is configured to activate or deactivate the main pump.

An advantage of this embodiment is that by deactivating the main pump, namely by switching off the switchable water pump during start up of the engine, a faster warm up of the coolant can be obtained and this increase of temperature can be used effectively to increase the oil temperature by means of the thermal interchange between the coolant and the oil in the heat exchanger.

According to a further embodiment of the invention, the engine oil temperature in the oil circuit is measured by a temperature sensor connected to the Electronic Control Unit.

This embodiment has the advantage of providing a reliable measure of the temperature of the oil in the oil circuit in order to provide a signal to the Electronic Control Unit of the engine.

Another embodiment of the invention provides an internal combustion engine managed by an Electronic Control Unit and equipped with an engine oil heating apparatus, the engine being equipped with an oil circuit having an oil heat exchanger, the apparatus comprising a main pump for circulating an engine coolant in a main coolant circuit and an auxiliary pump for circulating the coolant in an auxiliary coolant circuit, the auxiliary coolant circuit comprising the oil heat exchanger, wherein the main pump and the auxiliary pump are electrically connected to an Electronic Control Unit, which is configured for monitoring an engine oil temperature in the oil circuit and for energizing the auxiliary pump if the monitored oil temperature value is lower than a predetermined threshold value thereof.

Another embodiment of the invention provides a method for operating an internal combustion engine equipped with an oil circuft having an oil heat exchanger, the apparatus comprising a main pump for circulating an engine coolant in a main coolant circuit and an auxiliary pump for circulating the coolant in an auxiliary coolant circuit, the auxiliary coolant circuit comprising the oil heat exchanger, wherein the main pump and the auxiliary pump are electrically connected to an Electronic Control Unit, which is configured for monitoring an engine oil temperature in the oil circuit and for energizing the auxiliary pump if the monitored oil temperature value is lower than a predetermined threshold value thereof.

According to still another embodiment of the invention, the step of energizing the auxiliary pump is performed when the main pump is deactivated.

According to another embodiment of the invention, the monitoring of the temperature value of the oil is done by measuring a signal from an oil temperature sensor, the signal being proportional to the oil temperature.

Advantages of these embodiments of the method of the invention are substantially the same as those described for the oil heating apparatus above.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an automotive system; Figure 2 is a cross-section of an internal combustion engine belonging to the automotive system of figure 1; Figure 3 represents a graph of the friction between the engine's components as a function of oil temperature; Figure 4 represents a graph of coolant and oil temperatures during a new European driving cycle (NEDC); Figure 5 is a schematic representation of an oil heating apparatus according to an embodiment of the invention; and Figure 6 is a flowchart of a method of operating an internal combustion engine equipped with an oil heating apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Preferred embodiments will now be described with reference to the enclosed drawings.

Some embodiments may include an automotive system 100, as shown in Figures 1 and 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145.

A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150.

A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. Injectors 160 in fig. 1 are represented in a purely schematical way.

The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received a fuel source 190.

Each of the cylinders 125 has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NO traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110.

The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant temperature sensor 380, oil temperature sensor 385 and level sensors thereof, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with a memory system, or data carrier46O, and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices.

Figure 3 represents a graph of friction mean effective pressure (FMEP) as a function of engine oil temperature.

FMEP may be calculated experimentally by known methods and is a parameter indicative of internal losses of the engine due to friction, -The temperature of the oil circulating in an engine oil circuit deeply influences FMEP and, generally speaking, warmer oil corresponds to lower engine friction and therefore to lower FMEP.

For example, as expressed in Figure 4, an oil temperature T2 higher than oil temperature Ti brings a benefits in terms of a lower FMEP value F2 with respect to a FMEP value of Fl corresponding to temperature Ti.

For example an oil temperature of 40°C (T2) instead of 30°C (11) brings a benefits in FMEP at 2000 RPM (Revolutions Per Minute) of approximately 20% (F2 with respect to Fl), which corresponds to a benefit of approximately 4% in fuel economy. Different values may be found for different engine systems, but the principle that an higher oil temperature corresponds to lower engine friction expressed in terms of FMEP is generally valid.

Figure 4 represents a graph of engine coolant and engine oil temperatures during a new European driving cycle (NEDC). In Figure 4, curve A represents the speed of the vehicle during the NEDC, while curve B represents engine coolant temperature and curve C oil temperature. The difference T between the coolant temperature and the oil temperature may be equal to or even greater than 20°C, depending on the automotive system involved. Different values may be found for different engine cycles, the NEDC cycle being used here as an example.

Figure 5 is a schematic representation of an oil heating apparatus 505 according to an embodiment of the invention.

The internal combustion engine 110 is equipped with a cooling circuit 517 for circulating a coolant through the intemal combustion engine 110. The coolant circulating in the main cooling circuit 517 and in the engine 110 is sent to a radiator 560 having the function of transferring heat absorbed by the coolant to the ambient air. The coolant circulating in the engine cooling circuit 517 may be a mixture of water and of an antifreeze component.

The engine cooling circuit is equipped with a main pump 590 that sends the coolant into the engine block 120, whereby the coolant circulates therein for cooling the engine and then exits from the cylinder head 130 of the engine 110.

The main pump 590 may preferably be a switchable water pump 590 that circulates coolant between the engine 110 and the radiator 560 when the switchable water pump 590 is engaged and a thermostat 550 is open. The thermostat 550 is selectively opened to facilitate coolant flow between the engine 110 and the radiator 560. For example, the thermostat 550 may be opened when the temperature of coolant within the engine 110 exceeds a predetermined opening temperature. While the thermostat 550 is shown as being an outlet-side thermostat1 in other embodiments it may be an inlet-side thermostat.

The switchable water pump 590 may be driven by the engine 110, for example by rotation of the crankshaft 145 and may be connected to an Electronic Control Unit 450 of the engine 110 that can disengage the switchable water pump from the engine 110 according to need, for example during startup of the engine 110. Engagement or disengagement of the switchable water pump 590 from the engine 110 may be achieved by known means such as an electrically actuated clutch (not represented for simplicity).

The engine 110 is further equipped with an oil circuit 525 for lubrication of the various mechanical components thereof, in which an oil pump 595 draws oil from a crankcase sump 610 and distributes it to passages leading into the engine block 120.

From there, the oil goes to crankshaft bearings, camshaft bearings, valve shafts and other moving metal parts that would require lubrication to help avoid excess friction and heat buildup.

An oil heat exchanger 520 is provided in the oil circuit 525 to cool off the oil when an excessive oil temperature threshold is reached, thus avoiding excessive temperature thereof.

3D The oil heating apparatus 505 further comprises an auxiliary coolant pump 500 that circulates coolant in an auxiliary coolant circuit 515. The auxiliary coolant circuit 515 is designed in such a way to pass through the engine oil heat exchanger 520.

The auxiliary coolant pump 500 draws hot coolant directly from the coolant that circulates in the engine 110.

Preferably, the auxiliary pump 500 is an electric pump and can be energized following a command issued by the Electronic Control Unit 450.

The main cooling circuit 517 is equipped with a coolant temperature sensor 380 and the oil circuit 525 is equipped with an oil temperature sensor 385, both sensors 380385 being connected to the Electronic Control Unit 450.

Since as expressed in the graph of Figure 4, the coolant temperature is generally higher than the oil temperature, by circulating the coolant into the engine oil heat exchanger 520 and by achieving a thermal exchange therein, the engine oil heat exchanger 520 is used as an heater of the oil.

This is especially effective during engine warm up, when the coolant temperature is higher than the oil temperature when the switchable water pump 590 is turned off.

Figure 6 is a flowchart of a method of operating an internal combustion engine equipped with an oil heating apparatus 505 according to an embodiment of the invention.

At the start of the method, a check is made to verify if the switchable water pump 590 is on or off (block 900). If the switchable water pump 590 is on1 no action is performed on the auxiliary pump 500.

On the contrary if the switchable water pump 590 is off, the auxiliary pump 500 is activated (block 910).

Energizing the auxiliary pump 500 has the effect of warming up the oil by circulating coolant in the auxiliary circuit 515 drawn directly from the engine 110 through the oil heat exchanger 520.

Coolant circulation in the auxiliary circuit 515 may be continued, maintaining the auxiliary pump 500 on, until the temperature T011, for example measured by oil temperature sensor 385, increases and reaches a threshold temperature thereof TOjh* This may be obtained by repeatedly checking if temperature T is less than the threshold temperature TojiTh (block 920).

If this condition is satisfied, the auxiliary pump 500 is maintained on. When the temperature T011 reaches or exceeds the threshold temperature TojiTh, the auxiliary pump 500 is switched off (block 930).

This embodiment of the method allows the engine oil to reach quickly a suitable temperature for better operation at engine start up.

For some automotive systems the increase of oil temperature may be around 10 °C The coolant flow required may be provided by an auxiliary pump 500 of 20W, the provision of which has a minimal impact on engine friction. These values are merely cited as examples and may vary according to different engine systems.

When the engine 110 is warm, the auxiliary pump 500 may be switched off and the oil heat exchanger 520 operates as an oil cooler as per conventional solutions.

An increase in fuel economy of approximately 4% in a New European Driving Cycle (NEDC) can be obtained. The major benefits of the embodiments of the invention disclosed are applicable in cold weather temperatures.

Thanks to the various embodiments of the invention it is not necessary to equip the oil circuit with an oil cooler by-pass, as in conventional applications, thus saving costs.

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 examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary 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 may 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 NUMBERS

automotive system internal combustion engine (ICE) engine block 125 cylinder cylinder head piston crankshaft combustion chamber 155 cam phaser fuel injector fuel rail fuel pump fuel source 200 intake manifold 205 air intake duct 210 intake air port 215 valves of the cylinder 220 exhaust gas port 225 exhaust manifold 230 turbocharger 240 compressor 250 turbine 260 intercooler 270 exhaust system 275 exhaust pipe 280 exhaust aftertreatment device 290 VGT actuator 300 EGR system 3lOEGRcooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant temperature sensor 385 oil temperature sensor 400 fuel rail pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensor 445 accelerator pedal position sensor 450 electronic control unit (ECU) 460 data carrier 500 auxiliary pump 505 oil heating apparatus 510 LP EGR cooler 515 auxiliary coolant circuit 517 main coolant circuit 520 engine oil heat exchanger 525 engine oil circuit 550 thermostat 595 oil pump 610 oil sump 900 block 910 block 920 block 930 block

Claims

CLAIMS1. An apparatus (505) for heating oil in an internal combustion engine (110) equipped with an oil circuit (525) having an oil heat exchanger (520), the apparatus (505) comprising a main pump (590) for circulating an engine coolant in amain coolant circuit (517) and an auxiliary pump (500) for circulating the coolant in an auxiliary coolant circuit (515) the auxiliary coolant circuit (515) comprising the oil heat exchanger (520), wherein the main pump (590) and the auxiliary pump (500) are electrically connected to an Electronic Control Unit (450), which is configured for monitoring an engine oil temperature (lou) in the oil circuit (525) and for energizing the auxiliary pump (500) if the monitored oil temperature value (l,,) is lower than a predetermined threshold value thereof (TOIITh).
2. An apparatus as in claim 1, wherein the auxiliary pump (500) is an electric pump.
3. An apparatus as in claim 1, wherein the Electronic Control Unit (450) is configured to activate or deactivate the main pump (590).
4. An apparatus according to claim 1, wherein the engine oil temperature in the oil circuit (525) is measured by a temperature sensor (385) connected to the Electronic Control Unit (450).
5. An internal combustion engine (110) managed by an Electronic Control Unit (450) and equipped with an engine oil heating apparatus (505), the engine (110) being equipped with an oil circuit (525) having an oil heat exchanger (520), the apparatus (505) comprising a main pump (590) for circulating an engine coolant in a main coolant circuit (517) and an auxiliary pump (500) for circulating the coolant in an auxiliary coolant circuit (515), the auxiliary coolant circuit (515) comprising the oil heat exchanger (520), wherein the main pump (590) and the auxiliary pump (500) are electrically connected to an Electronic Control Unit (450), which is configured for monitoring an engine oil temperature (Touu) in the oil circuit (525) and for energizing the auxiliary pump (500) if the monitored oil temperature value (T01) is lower than a predetermined threshold value thereof (TOuITh).
6. A method for operating an intemal combustion engine (110) equipped with an oil circuit (525) having an oil heat exchanger (520) and with an oil heating apparatus (505), the apparatus (505) comprising a main pump (590) for circulating an engine coolant in a main coolant circuit (517) and an auxiliary pump (500) for circulating the coolant in an auxiliary coolant circuit (515), the auxiliary coolant circuit (515) comprising the oil heat exchanger (520), wherein the main pump (590) and the auxiliary pump (500) are electrically connected to an Electronic Control Unit (450), which is configured for monitoring an engine oil temperature (T01) in the oil circuit (525) and for energizing the auxiliary pump (500) if the monitored oil temperature value (T011) is lower than a predetermined threshold value thereof (TCITh).
7. A method according to claim 6, wherein the step of activating the auxiliary pump (500) is performed when the main pump (590) is deactivated.
8. A method according to claim 6, wherein the monitoring of the temperature value (T) of the oil is done by measuring a signal from an oil temperature sensor (385), the signal being proportional to the oil temperature.