GB2496916A

GB2496916A - Optimizing the transmission efficiency of a gearbox

Info

Publication number: GB2496916A
Application number: GB1120525.9A
Authority: GB
Inventors: Alberto Vassallo
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2011-11-28
Filing date: 2011-11-28
Publication date: 2013-05-29
Also published as: GB201120525D0

Abstract

A system for optimizing the transmission efficiency of a gearbox 2 of an internal combustion engine 110, and a related method and computer program. The engine 110 is provided with an engine oil circuit 10, the gearbox is provided with a gearbox oil circuit 11 and the system comprises at least one supply channel 3 to supply engine lubricating oil heated by said engine to the gearbox oil circuit 11 to warm the gearbox 2. At least one return channel 4 to return engine lubricating oil to said oil circuit 10 of the engine 110 and pressure control means 6 for regulating the amount of the engine lubricating oil supplied to heat said gearbox 2. Optionally the engine lubricating oil returns to the engine oil circuit 10 through channel 4 under the influence of gravity. The gearbox temperature may be measured by sensors 8 and / or estimated on the basis of mathematical models.

Description

Engine and gearbox integrated lubrication and thermo-management

Technical field

The present invention relates to a system and a related method for optimizing the to transmission efficiency of a gearbox of an internal combustion engine.

B ackg round Actual developments in vehicle design and production aim at improving vehicle economy and efficiency that lead to reduction of mass and drag resistance, package restrictions with an overall reduction of the engine and components dimensions, use of highly-efficient engines coupled to specific gearbox, e.g. manual transmission automated (known as MTA transmission) or dry dual clutch transmission (known as dDCT transmission).

The MTA and dDCT transmissions are cheap and are ideal solutions to be used in new vehicle economy applications, in fact, these type of transmission use a lubrication technology known in the art as splash lubrication" where the movement of the mechanical components inside the gearbox allow the required oil distribution, without requiring the use of dedicated gearbox oil pump for lubrication and cooling This type of transmissions, and in particular MTA and dDCT gearboxes, offer high efficiency in warmed conditions, but are subjected to slow warm-up in the case of cold start of the engine, during short vehicle driving, such as certification cycles and short urban commuting.

In other words, the slow and/or incomplete warm-up of the gearbox deteriorates the transmission efficiency because of the high gearbox oil viscosity.

Experimental tests carried out by the applicant show high loss of the transmission efficiency due to oil viscosity at low temperature, and in particular below 70° Celsius.

The high viscous state of the oil results in the consumption of large amount of energy need for driving the components of the transmission. Therefore, there is the need to reduce the amount of time required for reaching the desired temperature of the gearbox, thus avoiding transmission efficiency loss.

In particular, the reduced transmission efficiency causes at least the increasing of fuel consumption and of the emissions produced.

There are many sources of wasted thermal energy that could be used for speeding-up the gearbox warming, for example thermal energy coming from the engine, from engine coolant or cylinder head, or from engine exhaust gases. In all these cases must be carefully taken into account the amount of thermal energy draw from such sources for avoiding thermodynamics and mechanical efficiency losses.

In some proposed systems, the thermal energy coming from the exhaust gases produced by the engine is used to speed up the gearbox warming, but also this solution leads to efficiency losses of the exhaust aftertreatment devices. This problem is particularly fell in new diesel engine provided with many aftertreatment devices, each of which needs a large amount of thermal energy for reaching the desired operating temperature, for example temperature required for carrying out the regeneration process in a diesel particulate filter (DPF).

Alternatively the gearbox can be provided with dedicated heat sources, but also this solution is not applicable in view of targets of vehicle economy, package restriction and emissions reductions.

Therefore, it is an object of art embodiment of the present invention to provide an alternative and effective solution to the gearbox efficiency optimization by speeding-up its warming, without negatively affecting the thermodynamics and the mechanical efficiency of sources from which the thermal energy is drawn.

Moreover, it is another object of an embodiment of the present invention to provide a system, and a relative method, that allows optimizing the transmission efficiency of the gearbox, in particular by optimizing its heating process, especially for gearbox having no dedicated oil pump and oil cooler, such as TMA and dDCT gearboxes.

Summary

These and other objects are achieved by the system for optimizing the transmission efficiency of a gearbox coupled to an internal combustion engine according to claim 1, and the relative method according to claim 10. Further aspects of an embodiment of the present S invention are set out in the dependent claims.

The present system for optimizing the transmission efficiency of a gearbox of an internal combustion engine, wherein said engine has an engine oil circuit and said gearbox has a gearbox oil circuit, comprises at least one supply channel to supply engine lubricating oil heated by said engine to the gearbox oil circuit, to warm the gearbox, at least one return channel to return engine lubricating oil to said oil circuit of the engine, and pressure control means for regulating the amount of the engine lubricating oil supplied to heat said gearbox.

The engine lubricating oil is warmed relatively quickly due to the heat generated by the combustion process, also in the case of cold start and, advantageously, by means of the supply and return channels of the claimed system, the engine lubricating oil can be supplied to the gearbox for heating and lubricating the gearbox.

In other words, the heated engine oil is used for lubricating, and at the same time, quickly heating the gearbox by means of the fluidic connection between the engine oil circuit and the gearbox oil circuit. Advantageously the amount of the heated engine oil supplied to the gearbox leads to a speeding-up of the gearbox heating, thus reducing the oil viscosity and obtaining a high efficiency transmission also in the case of cold start of the engine and relative short real drive conditions.

it has to be understood that the term channel" is used herein to indicate any suitable means for allowing the fluidic connection of the engine to the gearbox, and vice versa, allowing the circulation of the engine lubricating oil into the gearbox.

Advantageously, use of the thermal energy of the engine lubricating oil for controlling the gearbox temperature has a limited impact on the engine efficiency, and advantageously there is no need for additional gearbox oil pump, especially in the case of splash lubricating gearboxes type, such as TMA and dDCT gearboxes.

According to an aspect of an embodiment of the present invention the engine oil circuit comprises at least one pump positioned upstream with respect to the at least one supply channel, thus the amount of the heated engine alt to be supplied into the gearbox can be regulated by said pressure control means.

Usually, the engine oil circuit comprises a main oil gallery, and the gearbox oil circuit comprises a main oil gallery and the at least one supply channel fluidicalty connects said engine main oil gallery to said gearbox main oil gallery. Moreover, according to a possible embodiment, the engine cit circuit comprises an oil pan and the at least one return channel fluidically connects the gearbox oil circuit to said engine oil pan.

In view of above the present system can be produced with simple piping changes, thus avoiding circuit complexity and production costs increase.

It has to be further noted that the in term of thermal balance, the energy drawn from the engine, and in particular from the engine oil used for warming the gearbox, does not negatively affect the mechanical and thermodynamics efficiency of the engine.

In another embodiment of the present invention a method for optimizing the gearbox transmission efficiency is provided. The method comprises the steps of supplying engine lubricating oil heated by the engine to the gearbox oil circuit through at least one supply channel, to warm the gearbox; returning engine lubricating oil to the oil circuit of the engine through the at least one return channel; and regulating the amount of the engine lubricating oil supplied to heat said gearbox through pressure control means.

According to an embodiment of the invention, in the present method the regulation of the amount of engine oil supplied to the gearbox is performed on the basis of at least the gearbox operating point, and/or of the gearbox temperature, and/or of the ambient temperature.

Preferably the gearbox operating point is evaluated at least by means of the speed, load and gear number It has to be noted that speed and load of the gearbox depend on the speed and load of the engine to which the gearbox is connected.

Advantageously, the present method allows to simply optimize the transmission efficiency of the gearbox by warming the same with the regulation of the amount of the engine oil to be supplied into the gearbox, by operating the pressure control means.

Another aspect of an embodiment of the invention provides a computer program comprising computer executable codes for carrying out the present method for optimizing the gearbox transmission efficiency.

The claimed system, and the related method, lead to art optimization of the transmission efficiency because of the quickly warming of the gearbox made by the circulation of the engine oil into the gearbox, without increase number of components, without require intermediate exchange circuits with additional thermal capacity, and without increasing calibration effort.

Brief Description of the Drawings

Further advantages and features of an embodiment of the present invention will be more apparent from the description below, provided with reference to the accompanying drawings, purely by way of a non-limiting example! wherein: * Figures 1 and 2 show possible embodiments of an automotive system on which the system according to the present disclosure can be used; * Figure 3 is a simplified scheme of the system for optimizing the transmission efficiency of a gearbox connected to an internal combustion engine according to the

present disclosure.

Detailed Description

Figures 1 and 2 show some embothments of an automotive system 100 on which the system 1 can be installed, which 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. 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 from a fuel source 190. Each of the cylinders 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 th! 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 NOx traps, hydrocarbon adsorbers, selective catalytic reduction (5CR) 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 to1 a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGS 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 VOT 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 and art 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. The program may embody the methods disclosed herein, allowing the CPU to carryout out the steps of such methods and control the ICE 110.

It has to be understood that the automotive system 100, described above in connection to figures 1 and 2, is only an example of a possible application of the present system and method for optimizing the transmission efficiency of a gearbox 2 of an internal combustion engine 110. Obvious!y, the system 1, that will be discussed in greater detail below in connection to figure 3, can be mounted on different types of internal combustion engine, having different layout. Moreover, the present system 1 can be used with internal combustion engine 110 connected to different types of gearbox 2, even though the system 1, and the related method, offer high advantages when used with splash lubricating gearboxes type, such as TMA and dDCT gearboxes, which are not provided with dedicated oil pump.

Figure 3 depicts a simplified scheme of the system 1 for optimizing the transmission efficiency of a gearbox 2 coupled to an intemal combustion engine 110. The internal combustion engine 110 shown in figure 3, similarly to that disclosed in figures 1 and 2, is lubricated in a conventional manner by a lubricating engine oil that circulates in a engine oil circuit 10.

The engine oil circuit 10, comprises at least an oil pan lOb, generally provided in the lower part of the engine 110, intended to receiving and accumulating the engine oil, and an oil S pump lOc, or similar flow means, for circulating the oil in the circuit 10.

The lubricating engine oil is circulated trough ducts leading the oil in many parts of the engine 110, thus the desired engine components can be lubricated. In particular, the engine oil circuit 10, comprises a main distribution duct, known as engine oil main gallery ba. After lubrication of the engine components the oil returns, by gravity, to the oil pan I Ob.

It has to be noted that, other components known in the art and not shown in figure 3, may be provided in the engine oil circuit 10, such as an oil filter, a heat exchanger, and oil temperature and level sensors 380, shown in figures 1 and 2.

As shown in figure 3, a gearbox 2, provided with a gearbox oil circuit 11, is connected to the engine 110 and the engine lubricating oU is used for lubricating the gearbox and for allowing quickly warming of the same, thus avoiding the undesired transmission efficiency losses in cold conditions.

In fact, according to an embodiment of the present invention the system I comprises at least one supply channel 3, that fluidically connects the oil circuit 10 of the engine 110 to the oil circuit 11 of the gearbox 2, and intended to supply engine lubricating oil heated by the engine to the gearbox oH circuit 11 to warm the gearbox 2. Moreover, the system 1 further comprises at Least one return channel 4, which fluidically connects the gearbox oil circuit 11 to the engine oil circuit 10, thus allowing the return of the engine lubricating oil from the gearbox oil circuit 11 to the engine oil circuit 10.

The engine lubricating oil undergoes a quickly warming due to the combustion process in the engine 110, and advantageously, the fluidically connection between the engine 110 and the gearbox 2, by means of the supply and return channels 3 and 4, allow the use of the engine lubricating oil for lubricating and heating the gearbox 2.

Preferably, the gearbox 2 is of the splash lubricating type, and is not provided with a dedicated gearbox oil pump, in fact, the engine lubricating oil is circulating in the engine oil circuit 10 by means of the engine oil pump lie and is supplied in the gearbox 2 by means of the supply channel 3. It has to be noted that the engine oil pump lie of the engine oil circuit 10 is preferably positioned upstream with respect to the supply channel 3. As shown in figure 3, the system 1 further comprises pressure control means 6 for regulating the amount of the engine lubricating oil supplied to heat said gearbox 2.

According to a possible embodiment control means comprises at Least one pressure control valve 6, preferabLy electrically actuated by the ECU 450, for regulating the engine oil flow in the supply channel 3, which also avoid an undesired increasing of the engine oil inside the gearbox 2.

The gearbox oil circuit 11 is provided at least with a main distribution duct, known as gearbox main oil gallery ii a, intended to leads the oil to the internal components of the gearbox 2 that need to be lubricated. In figure 3, internal components of the gearbox 2 are not shown, and generally comprise shaft bearings, synchronizers, etc. The engine lubricating oil supplied into the gearbox 2 is distributed to the gearbox components and then is accumulated in correspondence of the lower portion lib of the gearbox 2, generally by gravity.

According to a preferred embodiment, the supply channel 3 fluidically connects the main oil gallery 1 Ga of the engine oil circuit 10 and the main oil gallery 11 a of the gearbox oil circuit 11, and the return channel 4 fluidically connects the gearbox oil circuit 11, and in particular the gearbox lower portion 11 b where the oil is accumulated, to the oil pan lOb of the engine oil circtht 10.

Obviously, the connection between the engine 110 and the gearbox 2, and in particular the connection of the engine main oil gallery Wa with the gearbox main oil gallery ii, and of the gearbox oil circuit with the engine oil pan lOb, respectively by means of the supply 3 and return 4 channels, is realized in a seal-tight manner, thus avoiding any leakage.

The return of the oil into the engine oil circuit 10 is preferably obtained by gravity trough the return channel 4.

In the embodiment shown in figure 3, the return channel 4 is inclined with respect to a horizontal plane, in order to facilitate the gravity drain of the oil from the gearbox lower portion llb into the engine oil pan lab.

At the same time the inclination of the return channel 4 avoids the undesired circulation of the oil from the engine oil pan lob into the gearbox lower portion 11 b, especially during real drive when the vehicle, and also the engine and gearbox undergo lateral accelerations. It has to be understood that the inclination of the return channel 4 is measured from an horizontal plane, i.e. the substantially horizontal surface of the lower portion of the engine, or the horizontal surface (the street) on which the vehicle is moving. Preferably the inclination of the return channel 4 with respect to the horizontal is of 450* According to Other possible embodiments the system I further comprises means 7 for preventing the circulation of the engine lubricating oil from the engine oil circuit 10 to the gearbox oil circuit 11 trough the at least one return channel 4. Preferably) at least one check valve 7 prevents the passage of the lubricating oil from the engine oil circuit 10 to the gearbox oil circuit 11 trough the return channel 4. In particular, the check valve 7 avoids the circulation of the engine lubricating oil from the engine oil pan lOb into the gearbox lower portion 11 b. As will be disclosed herein below, other means can be provide for preventing the passage of the lubricating oil from the engine oil circuit 10 to the gearbox oil circuit 11 trough the return channel 4, such as electrically actuated valves connected to the ECU 450, As shown in figure 3, the present system 1 further comprises an electronic control unit ECU 450 for the internal combustion engine 110 comprising a digital central processing unit CPU and a storage memory, connected to said pressure control means 6, and in particular to the electricafly controlled pressure control valve 6 for regulating the amount of heated engine oil supplied to the gearbox 2, thus controlling the heating of the gearbox. As will be disclosed later, ECU 450 operates the pressure control valve 6 for regulating the oil amount supplied from the engine 110 to the gearbox 2, at least on the basis of the gearbox operating point, andlor the ambient temperature and/or the gearbox temperature. which are measured by means of sensors (8) 9) and/ar estimated on the basis of mathematical models.

For these reasons, the ECU 450 is also connected to the gearbox 2 for deriving information on its operating point, and in particular on at least speed, load and gear number, and it is also connected to temperature sensors 8 and 9, respectively for deriving temperature data of the gearbox and of the ambient.

It has to be understood that engine speed and load are transmitted from the engine output shaft, e.g. the crankshaft, to the gearbox input shaft, e.g. the gearbox main shaft. Thus, load and speed at the output shaft of the engine are equal to speed and load at the input shaft of the gearbox.

In the case the system 1 is provided with electrically actuated means 7 for preventing the circulation of the engine lubricating oil from the engine oil circuit 10 to the gearbox oil circuit 11 trough the at least one return channel 4, such as an electrically actuated stop valve, the ECU 450 is also connected to it (connection is not shown in figure 3). The electrically actuated stop valve is operated by the ECU 450 when there is the need to stop the oil flow from the engine 110 to the gearbox 2 trough the return channel 4, especially for preventing undesired oil circulation from the engine oil pan 1 Ob to the gearbox oil lower portion 11 b, during real driving conditions when the vehicle undergoes lateral accelerations.

A further aspect of an embodiment of the present invention relates to a method for optimizing the gearbox transmission efficiency of an engine, the method comprises the steps of supplying engine lubricating oil heated by the engine to the gearbox oil circuit 11 through at least one supply channel 3 to warm the gearbox 2; returning engine lubricating oi to said oil circuit 10 of the engine 110 through at least one return channel 4; and regulating the amount of the engine lubricating oil supplied to heat said gearbox 2 through pressure control means 6.

The regulation of the amount of the engine lubricating oil supplied to heat the gearbox 2, by means of pressure control means 6, can be performed on the basis of accurate control strategies a'so correlated to the engine control strategies.

According to an embodiment of the present invention, in the present method the regulation of the amount of engine oil supplied to the gearbox is performed on the basis of at least the gearbox operating point evaluated at least by means of speed, load and gear number, and/or of the gearbox temperature, and/or of the ambient temperature.

It has to be noted that the gearbox operating point, the gearbox temperature and ambient temperature are measured by said sensors and/or estimated on the base of mathematical models.

In fact, as already disclosed above, the ECU 450 is connected also to one or more gearbox temperature sensors S and to one or more ambient temperature sensors 9, in order to derive temperature value that can be used for regulating the amount of engine oil supplied to the gearbox its warming.

S

According to a possible embodiment of the present invention the amount of the oil to be supplied from the engine 110 to the gearbox 2, is derived on the basis of operating point of the gearbox, and in particular on the basis of the load, the speed and of the gear number, on the bases of a preset map of values stored in the ECU 450.

In particular, a map of values for each gear is stored into the ECU, and from said map can be derived the desired oil amount, and in particular the pressure of the engine oil to be supplied into the gearbox, as a function of the brake mean effective pressure (BMEP) and the rotation speed of the gearbox. As already mentioned above, gearbox speed and load at the gearbox input shaft, e.g. gearbox main shaft, are equal to speed and load of the engine at its output shaft.

Therefore for each gearbox operating point is possible to derive the desired pressure of the engine oil to be supplied from the engine into the gearbox, and ECU 450 operates the pressure control valve 6 in order to regulate the amount of the oil supplied from the engine oil circuit 10 to the gearbox oiL circuit 11 trough the supply channel 3.

Moreover, according to a possib'e embodiment of the invention, in the case the system 1 is provided with electrically actuated means 7 for preventing the undesired circulation of the engine oil from the engine oil pan lob to the gearbox oil circuit 11 trough the return channel 4, i.e. a stop valve, the ECU 450 can use accelerations data derived from acceleration sensors (not shown), installed on the vehicle, and already used for example for stability control systems, to operates said stop valve for preventing oil circulation from the engine to the gearbox trough the return channel 4 on the basis of accelerations of the vehicle during real driving conditions.

The method for optimizing the transmission efficiency of the gearbox may be carried out by means of a computer program comprising program codes (computer executable codes) for performing the method steps already described above. n

The computer program comprises computer executable codes that can be stored on the ECU, or on a computer readable medium, or a storage unit, such as CD, DVD, flash memory, hard-disk, or the like. More in detail the engine control unit (ECU) comprises a digital central processing unit (CPU) and a storage memory for storing a computer program for carrying out the above disclosed method, the digital central processing unit (CPU) is able to receive and to execute said computer executable codes of the computer program.

The computer program comprises computer executable code for supplying engine lubricating oil heated by the engine to the gearbox oil circuit 11 through the supply channel 3 to warm the gearbox 2; computer executable code for returning engine lubricating oil to the oil circuit 10 of the engine 110 through the return channel 4; and computer executable code for regulating the amount of the engine lubricating oil supplied to heat the gearbox 2 through pressure control means 6.

Advantageously the system 1, and the related method, by using the engine lubricating oil that circulates between the engine 110 and the gearbox 2 trough at least one supply channel 3 and at least one return channel 4, increase the transmission efficiency due to the quickly warming up of the gearbox, leading to a potential reduction of carbon dioxide (GO2) emissions, of around 2.5% and up to 5% in real driving conditions with ow ambient temperature.

Moreover, the use of the engine lubricating oil also for the gearbox lubrication produce a package and a cast-effective solution, which is opened to further layout optimizations between engine and the gearbox.

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.

List of reference numerals 1: system 2: gearbox 3: supply channel 4: return channel 6: pressure control valve 7: check valve 8: gearbox temperature sensor 9: ambient temperature sensor 10: engine oil circuit Wa: engine oil main gallery lob:, engine oil pan jOe: engine oil pump ii: gearbox oil circuit 11 a: gearbox oil main gallery jib: gearbox lower portion 100: Automotive system 110: Internal Combustion Engine 120: Engine block 125: Cylinder 130: cylinder head 135: camshaft 140: Piston Crankshaft 150: Combustion chamber 155: Cam phaser 160: Fuel injector 170: Fuel rail 180: High pressure fuel pump 190: Fuel source 200: Intake manifold 205: Air intake line 210: Intake port 215: Valves 220: Port 230: Turbocharger 240: compressor 250: Turbine 260: Intercooler 270: Exhaust system 275: Exhaust line 280: After-treatment devices 290: Variable Geometry Turbine (VGT) actuator 300: Exhaust Gas Recirculation (EGR) system 310: EGR cooler 320: EGR valve 330: Throttle body 340: Mass airflow and temperature sensor 350: Manifold pressure and temperature sensor 360: Combustion pressure sensor 380: Coolant and oil temperature and level sensors 400: Fuel rail pressure sensor 410: Cam position sensor 420: Crank position sensor 430: Exhaust pressure and temperature sensor 440: EGR temperature sensor 445: Accelerator pedal position sensor 450: Electronic Control Unit (ECU)

Claims

<claim-text>CLAIMS1. A system (1) for optimizing the gearbox (2) transmission efficiency of an internal combustion engine (110), said engine having an engine oil circuit (10) and said gearbox having a gearbox oil circuit (11), the system comprising: -at least one supply channel (3) to supply engine lubricating oil heated by said engine to the gearbox oil circuit (ii) to warm the gearbox (2), -at least one return channel (4) to return engine lubricating oil to said oil circuit (10) of the engine (110), and -pressure control means (6) for regulating the amount of the engine lubricating oil supplied to heat said gearbox (2).</claim-text> <claim-text>2. The system according to claim 1, wherein said engine oil circuit (10) comprises a main oil gallery (lOa), and said gearbox oil circuit (11) comprises a main oil gallery (ha), said at least one supply channel (3)fluidically connecting said engine main oil gallery (ba) to said gearbox main oil gallery (ha).</claim-text> <claim-text>3. The system according to claim 1 or 2, wherein said engine oil circuit (10) comprises an oil pan (lob), said at least one return channel (4) Iluidically connecting said gearbox oil circuit (11) to said engine oil pan (lob).</claim-text> <claim-text>4. The system according to any of the preceding claim, wherein said pressure control means comprises at least one pressure control valve (6) for regulating the amount of the engine lubricating oil supplied to said gearbox trough said at least one supply channel (3).</claim-text> <claim-text>5. The system according to any of the preceding claim, further comprising means (7) for preventing the circulation of the engine lubricating oil from the engine oil circuit (10) to the gearbox oiL circuit (11) trough said at least one return channel (4).</claim-text> <claim-text>6. The system according to any of the preceding claim, wherein the engine lubricating oil returns in said engine oil circuit (10) trough said at least one return channel (4) by gravity.</claim-text> <claim-text>7. The system according to any of the preceding claim, wherein said engine oil circuit (10) comprises at least one pump (bc) positioned upstream with respect to said at least one supply channel (3).</claim-text> <claim-text>6. The system according to any of the preceding claim, further comprising at least one gearbox temperature sensor (B).</claim-text> <claim-text>9. The system according to any of the preceding claim, further comprising an electronic control unit ECU (450) for said engine (110) comprising a digital central processing unit (CPU) and a storage memory, connected at [east to said pressure control means (6) for regulating the amount of the engine lubricating oil supplied to heat said gearbox (2).</claim-text> <claim-text>10. A method for optimizing the gearbox (2) transmission efficiency of an internal combustion engine (110), said engine having an engine oil circuit (11) and said gearbox having a gearbox oil circuit, the method comprising the steps of: -supplying engine lubricating oil heated by said engine to the gearbox oil circuit (11) through at least one supply channel (3) to warm the gearbox (2); -returning engine lubricating oil to said oil circuit (10) of the engine (110) through at least one return channel (4); and -regulating the amount of the engine lubricating oil supplied to heat said gearbox (2) through pressure control means (6), 11. The method according to claim 10, further comprising the step of regulating the amount of the engine lubricating oil supplied to heat said gearbox (2) through pressure control means (6) on the basis of at least the gearbox operating point, and/or the gearbox temperature and/ore the ambient temperature.12. The method according to claim 10 or 11, wherein the gearbox operating point, and/or the gearbox temperature and/or the ambient temperature are measured by means of sensors (8, 9) andlor estimated on the basis of mathematical models.13. The method according to any claim 10 -12, wherein the amount of the engine lubricating oil supplied to heat said gearbox (2) is derived on the basis of the gearbox operating point from a map of preset values stored in the engine control unit ECU (450).14. A computer program comprising computer executable codes for optimizing the gearbox (2) transmission efficiency of an internal combustion engine (110), said computel program being stored on computer-readable medium or a suitable storage unit and comprises: -a computer executable code for supplying engine lubricating oil heated by said engine to the gearbox oil circuit (it) through at Least one supply channel (3)to warm the gearbox (2); -a Gomputer executable code for returning engine lubricating oil to said oil circuit (10) of the engine (110) through at least one return channel (4); and -a computer executable code for regulating the amount of the engine lubricating oil supplied to heat said gearbox (2) through pressure control means (6).15. A computer program product including a readable medium in which a computer program according to claim 14 is stored.</claim-text>