GB2502369A

GB2502369A - An Engine Lubrication System Flow Control Arrangement Which Includes Piston Oil Jet Cooling and a Variable Output Oil Pump.

Info

Publication number: GB2502369A
Application number: GB201209338A
Authority: GB
Inventors: Davide Donna; Andrea Almondo; Luigi Cuccia
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2012-05-25
Filing date: 2012-05-25
Publication date: 2013-11-27
Anticipated expiration: 2032-05-25
Also published as: GB201209338D0; GB2502369B

Abstract

A lubrication system 600 for an i.c. engine (110 Fig 1) has a variable displacement oil pump 605, piston oil jet cooling 700, and oil flow control. A pump inlet 635 connects to a sump 610, a pump outlet 640 connects to a main gallery 615, and oil pressure in primary and secondary control chambers 675, 680 controls pump displacement. The piston cooling jets are connected to an auxiliary gallery 695 having an associated control valve 710 with at least four ports. The first port 720 connects to the secondary control chamber, the second port 725 connects to the auxiliary gallery, the third port 730 connects to the main gallery, and the fourth port 735 connects to the oil sump 610. The valve has a valve member for interconnecting the ports, moveable between a first and second position, such that in the first position, the third port is connected to the second port and contemporaneously the first port is connected to the fourth port, and the second position, in which the second port is disconnected from the third port and contemporaneously the third port is connected to the first port.

Description

LUBRICATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD

The present invention relates to a lubrication system for an internal combustion engine, particularly an internal combustion engine of a motor vehicle.

BACKGROUND

It is known that an internal combustion engine of a motor vehicle comprises a lubrication system for lubricating the rotating or sliding components of the engine.

The lubrication system essentially comprises an oil pump driven by the engine, which draws a lubricating oil from an oil sump and delivers it under pressure to a main oil gal-lery that is made in the engine block.

The main oil gallery is connected by several channels to a plurality of exit holes for lubri- cating crankshaft bearings (main bearings and big-end bearings), camshaft bearings op-erating the valves, tappets, and the like, before the lubricating oil returns into the oil sump again.

In order to reduce polluting emissions and fuel consumption, the oil pump of modern lu- brication systems may be a variable displacement oil pump (VDOP), which advanta-geously allows to regulate the pressure and the flow rate of the lubricating oil which is fed into the main gallery.

The VOOP generally comprises an external casing provided with an oil inlet and an oil outlet, an operative chamber defined inside the external casing which is in communica-tion with the oil inlet and the oil outlet, and a rotor which is mounted to rotate about a fixed axis inside the operative chamber.

The rotor carries a plurality of radial vanes, which can individually slide to and from the axis of rotation and which divide the operative chamber into several pumping compart-ments for pumping the oil from the oil inlet to the oil outlet.

The operative chamber is partially delimited by an annular element or ring, which is ac-commodated inside the external casing to eccentrically enclose the rotor, and which can be moved in different operating positions so as to vary the eccentricity of the rotor, there-by modifying the dimensions of the pumping compartments and thus the displacement of the pump.

The movements of the annular element are caused by the pressures into two control chambers, namely a primary control chamber and a secondary control chamber, which are defined inside the VDOP external casing, separated from the operative chamber by the above mentioned annular element.

More particularly, a pressure increase in the control chambers pushes the annular ele-ment from a position of maximum eccentricity towards a posilion of minimum eccentricity, in contrast with a spring, thereby reducing the displacement of the pump and thus the pressure and the flow rate of the lubricating oil in the main oil gallery.

The first control chamber is usually in direct communication with the main oil gallery, whereas the secondary control chamber is in communication with an electrically driven three-way control valve, which is provided for selectively connect the secondary control chamber to the main oil gallery or to the oil sump.

In this way, when the second control chamber communicates with the oil sump, whose internal pressure is usually equal to the atmospheric pressure, the annular element is on- ly subjected to the force exerted by the pressure of the lubricating oil in the primary con-trol chamber. As a consequence, as long as a this force is below the force exerted by the spring, the annular element remains in the position of maximum eccentricity. If converse-ly the force exerted by the pressure in the primary control chamber exceeds the force exerted by the spring, the annular element moves towards the position of minimum ec-centricity, thereby automatically reducing the displacement of the pump and thus the pressure of the lubricating oil. In this way, the pressure of the lubricating oil in the lubrica-tion system is effectively prevented from exceeding a predetermined upper level which depends on the preload of the spring.

When the second control chamber communicates with the main oil gallery, the annular element is subjected to the force exerted by the pressure of the lubricating oil in both the control chambers. Clearly, this force is greater than the force exerted in the primary con-trol chamber only, so that the annular element will move to reduce the displacement of the pump when the pressure of the lubricating oil is lower than in the preceding case. As a consequence, the pressure of the lubricating oil in the lubrication system is effectively prevented from exceeding a predetermined level which is lower than the upper level mentioned above.

The above mentioned three-way control valve is generally controlled by an engine con-trol unit (ECU), which is configured to connect the second chamber to the main oil gallery or to the oil sump on the basis of one or more engine operating conditions, especially on the basis of the engine load.

In order to cool and lubricate the engine pistons and the related cylinders, modern lubri- cation systems may also comprise a plurality of piston cooling jets (PCJ) which are indi- vidually provided for jetting lubricating oil into an upper crankcase area towards an en-gine piston.

The PCJs are usually connected to an auxiliary oil gallery, also referted as Oil Pistons Cooling Jets (OPCJ) gallery, which is made in the engine block of the internal combus-tion engine and which is in communication with the main oil gallery.

More particularly, the communication between the main oil gallery and the auxiliary oil gallery may be achieved by means of an electrically actuated ON-OFF valve, conven-tionally referred as Oil Piston Cooling Jets (OPCJ) valve.

In this way, when the OPCJ valve is open, the lubricating oil flows from the main oil gal-lery into the auxiliary oil gallery and exits form the OPJs. Conversely, when the OPCJ valve is closed, the lubricating oil does not flow into the auxiliary oil gallery and no lubri-cating oil is ejected from the PCJs.

The OPCJ valve is generally controlled by the ECU, which is configured to open and closed the OPCJ valve on the basis of one or more engine operating parameters, espe-cially on the basis of the engine temperatures.

In view of the above, it follows that modern lubrication systems usually comprise a rela- tively high number of valves, each of which needs to be properly controlled, thereby mak-ing the lubrication system quite complicated and expensive.

Therefore, an object of an embodiment of the invention is that of providing a lubrication system which is more simple and cheap, without compromising its functionalities.

Another object is to achieve this goal with a simple, rational and rather inexpensive solu-tion.

SUMMARY

These and/or other objects are attained by the features of the embodiments of the inven-tion as reported in the independent claims. The dependent claims recite preferred and/or especially advantageous features of the embodiments of the invention.

More particularly, an embodiment of the invention provides a lubrication system for an internal combustion engine, comprising: -a variable displacement oil pump (VDOP) having an inlet, an outlet, a primary control chamber and a secondary control chamber, wherein the displacement of the oil pump is determined by the pressures in the primary and secondary control chambers, -an oil sump connected to the inlet of the oil pump, -a main gallery connected to the outlet of the oil pump and to the primary control cham-ber, -at least a piston cooling jet for cooling a piston of the engine, -an auxiliary gallery connected to the piston cooling jet, and -a control valve having a first port connected to the secondary control chamber, a se-cond port connected to the auxiliary gallery, a third port connected to the main gallery, a fourth port connected to the oil sump, and a valve member movable between a first posi-tion, in which the third port is connected to the second port and contemporaneously the first pod is connected to the fourth pod, and a second position, in which the second port is disconnected from the third port and contemporaneously the third port is connected to the first pod.

Thanks to this solution, it is advantageously possible to control the PCJs and the VDOP with the single four-way control valve disclosed above, thereby simplifying the lay out of the entire lubrication system and thus reducing its cost.

In tact, when the valve member of the control valve is in the first position, the VDOP can operate up to its upper pressure level (pressure in the second control chamber is that of the oil sump, typically atmospheric pressure) and contemporaneously the lubricating oil can be ejected by the PCJs (main oil gallery in communication with the auxiliary gallery).

When conversely the valve member is in the second position, the VDOP can operate up to its lower pressure level only (pressure in the second control chamber is that of the main oil gallery) and contemporaneously the lubricating oil is prevented to exit from the PCJs (auxiliary gallery disconnected from the main oil gallery).

According to an aspect of the invention, the control valve may be configured to connect the second port to the fourth port as the valve member is in the second position.

This solution has the advantage that, when the valve member is in the second position, the pressure in the auxiliary gallery is that of the oil sump (typically the atmospheric pressure), thereby guaranteeing that no lubricating oil can exit from the PCJs when the displacement of the VDOP is minimum.

According to another aspect of the invention, the control valve may comprise an electric actuator to move the valve member. The electric actuator may be for example a solenoid incorporated in the control valve and interacting directly with the valve member.

This aspect of the invention has the advantage of allowing an electric actuation of the control valve, which can be easily operated and controlled.

According to still another aspect of the invention, the control valve may also comprise re-silient means, typically a spring, to move the valve member.

This aspect of the invention has the advantage of simplifying the electric actuator, since the electric actuator may be configured to actuate the movement of valve member in one direction only, whereas the movement in the opposite direction may be actuated by the resilient means.

In this regard, an aspect of the invention provides that the resilient means are arranged to move the valve member towards the first position, and the electric actuator is arranged to move the valve member towards the second position.

This aspect of the invention has the advantage that, in case of a failure of the electric ac- tuator, the valve member of the control valve remains in the first position, which corre- sponds to the upper pressure level of the VDOP, thereby always guaranteeing a suffi-cient lubrication of the engine.

According to another aspect of the invention, the piston cooling jet may comprise a check valve for selectively opening and closing the piston coaling jet.

The presence of a check valve has the advantage of guaranteeing that the lubricating oil is ejected by the PCJ only if the auxiliary gallery is connected to the main gallery and the VDOP is generating a sufficient pressure level. In this way, if the control valve is blocked in the first position due to a failure, the check valve prevents the ejection of the lubricat-ing oil from the PCJ when the pressure in the lubrication system is too low. In addition, the check valve prevents the auxiliary gallery and/or the main gallery from being com-pletely emptied.

Another embodiment of the invention provides a method for operating the lubrication sys-tern disclosed above, wherein the method comprises the steps of: -monitoring an engine load, -moving the valve member in the first position if the engine load exceeds a predeter-mined threshold value, -moving the valve member in the second position if the engine load is below the thresh-old value.

Thanks to this solution, the PCJs are open and the VOOP is allowed to operate up to its upper pressure level only when the engine load i high, namely when there is the maxi-mum need for lubrication and cooling of the engine components, whereas the PCJs are closed and the VUOP is limited to its lower pressure level when the engine load is low, thereby advantageously reducing the fuel consumption of the internal combustion en-gine.

The method according to this embodiment of the invention 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 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.

Another embodiment of the invention provides an apparatus for operating the lubrication system disclosed above, wherein the apparatus comprises: -means for monitoring an engine load, -means for moving the valve member in the first position if the engine load exceeds a predetermined threshold value, -means for moving the valve member in the second position if the engine load is below the threshold value.

This embodiment ofhe invention has substantially the same advantages of the method explained above, in particular that of guaranteeing a proper lubrication of the engine while reducing the fuel consumption.

Still another embodiment of the invention provides an automotive system comprising an internal combustion engine, the lubrication system disclosed above, and an electronic control unit configured to: -monitor an engine load, -move the valve member in the first position if the engine load exceeds a predetermined threshold value, -move the valve member in the second position if the engine load is below the threshold value.

Also this embodiment of the invention has substantially the same advantages of the method explained above, in particular that of guaranteeing a proper lubrication of the en-gine while reducing the fuel consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention wilt now be described, by way of example, with reference to the accompanying drawings.

Figure 1 shows an automotive system.

Figure 2 is the section A-A of an internal combustion engine of the automotive system of figure 1.

Figure 3 is a schematic representation of a lubrication system for the internal combustion engine of figure 2, shown with the valve member of the control valve in a first position.

Figure 4 is a schematic representation of a lubrication system of figure 3, shown with the valve member of the control valve in a second posftion.

Figure 5 is a schematic representation of a lubrication system for the internal combustion engine of figure 2, according to another embodiment of the invention.

DETAILED DESCRIPTION

Some embodiments may include an automotive system 100, as shown in figures 1 and 2, which includes an internal combustion engine (ICE) 110, for example a Diesel engine or a gasoline engine. The ICE 110 comprises 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 mix-ture (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 in-take port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail in fluid communication with a high pressure fuel pump 180 that increases the pies-sure of the fuel received from 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 at least one exhaust 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 pipe 205 may provide air from the ambient environment to the intake mani-fold 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 tur-bocharger 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 intake pipe 205 and manifold 200. An intercooler 260 disposed in the intake pipe 205 may reduce the temperature of the air. The turbine 250 rotates by receiving ex-haust 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. 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 gases exit the turbine 250 and are directed into an exhaust system 270.

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 traps1 hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters. Other embodiments may include an exhaust gas recircu- lation (EGR) system 300 coupled between the exhaust manifold 225 and the intake man- ifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the tempera-ture of the exhaust gases in the EGS 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 and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a camshaft position sensor 410, a crankshaft 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 460 and an interface bus. The memory system 460 may include various storage types including optical storage, magnetic stor- age, solid state storage, and other non-volatile memory. The interface bus may be con-figured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The CPU is configured to execute instructions stored as a program in the memory system 460, and send and receive signals to/from the interface bus. The program may embody the methods disclosed herein, allowing the CPU to car-ryout out the steps of such methods and control the ICE 110.

As shown in figure 3, the automotive system 100 may include a lubrication system 600 for lubricating the rotating and sliding components of the ICE 110.

The lubrication system 600 comprises an oil pump 605 driven by the ICE 110, which is provided for drawing a lubricating oil from an oil sump 610 and for delivering it under pressure to a main oil gallery 615. Some embodiments may comprise one or more de-vices 620 located between the oil pump 605 and the main oil gallery 615, for filtering and/or cooling the lubricating oil.

The oil sump 610 is a single component that is usually fixed at the bottom of the engine block 120 (see also fig. 2), whereas the main oil gallery 615 is usually made inside the casting of the engine block 120.

The main oil gallery 615 is connected by several channels, globally indicated with 625 in figure 3, to a plurality of exit holes (not shown) for lubricating crankshaft bearings (main bearings and big-end bearings), camshaft bearings operating the valves, tappets, and the like, from which the lubricating oil finally returns into the oil sump 610.

The lubrication system 600 further comprises an auxiliary oil gallery 695, which is made in the engine block 120 and which is connected to a plurality of piston cooling jets (PCJs) 700. The PCJs 700 are nozzles individually provided for ejecting lubricating oil into an upper crankcase area towards a respective engine piston 140. In this way, the lubricating oil ejected by the PC.Js 700 lubricates and cools down the engine pistons 140 before re-turning into the oil sump 610 again.

Each PCJ 700 may comprise a mechanical check valve 705, which includes a valve member and a spring for pushing the valve member to close the PCJ 700. In this way, the check valve 705 opens the PCJ 700 only if the pressure of the lubricating oil in the auxiliary oil gallery 695 exceeds a predetermined threshold value, which is determined by the preload of the spring.

In order to reduce polluting emissions and fuel consumption, the oil pump 605 of the lu-brication system 600 is a variable displacement oil pump (VOOP).

In particular, the oil pump 605 comprises an external casing 630 provided with an oil inlet 635 and with an oil outlet 640. The oil inlet 635 is in communication with the oil sump 610, whereas the oil outlet 640 is in communication with the main oil gallery 615 via the filtering and cooling device(s) 620.

The external casing 630 encloses an operative chamber 645, which is in communication with the oil inlet 635 and with the oil outlet 640. A rotor 650 is mounted inside the opera-tive chamber 645 and is coupled to the engine crankshaft 145 to rotate about a fixed axis A. The rotor 650 carries a plurality of radial vanes 655, which can individually slide, into respective slots of the rotor 650, to and from the axis of rotation A, and which divide the operative chamber 645 into several pumping compartments 660 for pumping the lubricat-ing oil from the oil inlet 635 to the oil outlet 640.

The lateral perimeter of the operative chamber 645 is delimited by an annular element 665, which is accommodated inside the external casing 630 so as to eccentrically en-close the rotor 650. The annular element 665 is hinged to the external casing 630 by an articulate joint 670, so as to be able to rotate across different operating positions, thereby varying the relative eccentricity of the rotor 650, the dimensions of the pumping com-partments 660 and thus the global displacement of the oil pump 605.

The external casing 630 encloses also a spring 690 and two control chambers, namely a primary control chamber 675 and a secondary control chamber 680, which are provided for regulating the movements of the annular element 665.

The control chambers 675 and 680 are partially delimited by the annular element 665, which separates them from the operative chamber 645. The primary control chamber 675 is also separated from the secondary control chamber 680 by a compressible gas-kets 685 that rests on the annular element 665.

The spring 690 acts on the annular element 665 so as to push it towards a position of maximum eccentricity (shown in figure 3), which corresponds to a configuration of maxi-mum displacement for the oil pump 605.

The control chambers 675 and 680 are located so that the inside pressure pushes the annular element 665, against the action of the spring 690, towards a position of minimum eccentricity (not shown), which corresponds to a configuration of minimum displacement for the oil pump 605.

The primary control chamber 675 is in communication with the main oil gallery 615 through a direct conduit 702, and the secondary control chamber 680 is connected to a four-way two-position control valve 710.

The control valve 710 comprises a valve body 715 having four ports that, through re-spective conduits, are in communication with the secondary control chamber 680, the auxiliary oil gallery 695, the main oil gallery 615 and a fourth port 735 the oil sump 610.

More precisely, the valve body 715 includes a first port 720 in communication with the secondary control chamber 680, a second port 725 in communication with the auxiliary oil gallery 695, a third port 730 in communication with the main oil gallery 615 and a fourth port 735 in communication with the oil sump 610.

The control valve 710 further comprises a valve member 740, which is movable inside the valve body 715 between a first position and a second position. A spring 745 is ar- ranged to push the valve member 740 towards the first position, whereas an electric ac-tuator 750 is arranged so that, when electrically powered, it moves the valve member 740 toward the second position, against the action of the spring 745. The electric actua- tor 750 may be for example a solenoid incorporated in the control valve 710 and interact-ing directly with the valve member 740.

When the valye member 740 is in the first position (shown in figure 3), the first port 720 communicates with the fourth port 735 and contemporaneously the second port 725 communicates with the third port 730. In this way, the secondary control chamber 680 of the oil pump 605 is in direct communication with the oil sump 610, whose internal pres-sure (i.e. atmospheric pressure) is lower than the pressure in the main oil gallery 615. In this way, the annular element 665 is actually subjected to the force exerted by the pres-sure of the lubricating oil in the primary control chamber 675 only. As a consequence, as long as a this force is below the force exerted by the spring 690, the annular element 665 remains in the position of maximum eccentricity. If the force exerted by the pressure in the primary control chamber 675 exceeds the force exerted by the spring 690, the annu- lar element 665 moves towards the position of minimum eccentricity, thereby automati-cally reducing the displacement of the pump 605 and thus the pressure of the lubricating oil. In this way, the pressure of the lubricating oil in the lubrication system 600 is effec-tively prevented from exceeding a predetermined upper pressure level, which depends on the preload of the spring 690. contemporaneously, the main oil gallery 615 is in direct communication with the auxiliary oil gallery 695, so that the lubricating oil can flow there-in to be ejected by the PCJs 700.

When the valve member 740 is in the second position (shown in figure 4), the first port 720 communicates with the third port 730 and contemporaneously the second port 725 communicates with the fourth pod 735. In this way, the secondary control chamber 680 of the oil pump 605 is in direct communication with the main oil gallery 615, whose inter- nal pressure is greater than the pressure in the oil sump 610. As a consequence, the an-nular element is actually subjected to the force exerted by the pressure of the lubricating oil in both the control chambers 675 and 680. Clearly, this force is greater than the force exerted in the primary control chamber 675 only, so that the annular element 665 will move to automatically reduce the displacement of the pump 605 when the pressure of the lubricating oil is lower than in the preceding case. In this way, the pressure of the lu- bricating oil in the lubrication system 600 is effectively prevented from exceeding a pre- determined level which is lower than the upper level mentioned above. Contemporane- ously, the auxiliary oil gallery 615 is disconnected from the main oil gallery 615 and con-nected to the oil sump 610. As a consequence, the pressure of the lubricating oil in the auxiliary oil gallery 695 drops to the pressure of the oil sump 610 (i.e. atmospheric pres-sure), thereby preventing any ejections of lubricating oil from the PCJs 700.

It should be understood that, in this context, the check valves 705 of the PCJs 700 are not essential and could be avoided. If present, the check valves 705 has the advantage of guaranteeing that the lubricating oil is ejected by the PCJs 700 only if the auxiliary oil gallery 695 is connected to the main oil gallery 615 and the pump 605 is generating a sufficient pressure level. In this way, if the valve member 740 is blocked in the first posi-tion due to a failure, the check valves 705 prevent the ejection of the lubricating oil from the PCJ5 700 when the pressure in the lubrication system 600 is too low, and additionally prevent the auxiliary oil gallery 695 and the main oil gallery 615 from being completely emptied.

The movements of the valve member 740 between the first and the second position are determined and controlled by the ECU 450, which is connected to the electric actuator 750 and which is configured to execute the operating procedure described below.

While the ICE 110 is running, the operating procedure provides for the ECU 450 to con-stantly monitor the current value of the engine load. The engine load may be represented andlor determined by the position of the accelerator pedal of the automotive system 100.

Accordingly, the current value of the engine load can be monitored by the ECU 450 by means of the accelerator pedal position sensor 445.

The current value of the engine load is compared with a predetermined threshold value.

This threshold value can be determined during an experimental activity executed on a test bench and then stored in the memory system 460.

When the current value of the engine load exceeds the threshold value, the ECU 450 does not supply electrical power to the electric actuator 750 of the control valve 710, so that the spring 745 moves the valve member 740 in the first position.

In this way, when the engine load is high, the ECU 450 activates the PCJs 700 and con-temporaneously allows the oil pump 605 to raise the pressure of the lubricating oil up to the upper level, thereby guaranteeing a sufficient lubrication and cooling of the ICE 110.

When the current value of the engine load is below the threshold value, the ECU 450 supplies electrical power to the electric actuator 750 of the control valve 710, so that the valve member 740 is moved in the second position.

In this way, when the engine load is low, the ECU 450 deactivates the PCJs 700 and contemporaneously allows the oil pump 605 to raise the pressure of the lubricating oil at most up to the lower level, thereby reducing the fuel consumption of the ICE 110.

Figure 5 shows a lubrication system 600 which differs from that disclosed above and il-lustrated in figure 3 and 4 only because the control valve 710 is configured so that, when the valve member 740 is in the second position, the auxiliary oil gallery 695 is simply dis- connected from the main oil gallery 615 but not connected to the oil sump 610. This em-bodiment of the invention works exactly as the preceding one and achieves the same advantages.

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 forgoing 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 in their legal equivalents.

REFERENCES

automotive system internal combustion engine 120 engine block cylinder cylinder head camshaft piston 145 crankshaft combustion chamber cam phaser fuel injector fuel rail 180 fuel pump fuel source intake manifold 205 air intake pipe 210 intake port 215 valves 220 exhaust port 225 exhaust manifold 230 turbocharger 240 compressor 250 turbine 260 intercooler 270 exhaust system 275 exhaust pipe 280 aftertreatment devices 290 VGT actuator 300 exhaust gas recirculation system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 in-cylinder pressure sensor 380 coolant and oil temperature and level sensors 400 fuel rail pressure sensor 410 camshaft position sensor 420 crankshaft position sensor 430 exhaust pressure and temperature sensors 440 EGR temperature sensor 445 accelerator pedal position sensor 450 ECU 460 memory system 600 lubrication system 605 oil pump 610 oil sump 615 main oil gallery 620 filtering and cooling device 625 channels 630 external casing 635 oil inlet 640 oil outlet 645 operative chamber 650 rotor 655 radial vanes 660 pumping compartments 665 annular element 670 articulate joint 675 primary control chamber 680 secondary control chamber 685 gasket 690 spring 695 auxiliary oil gallery 700 piston cooling jet 702 conduit 705 check valve 710 control valve 715 valve body 720 first port 725 second port 730 third port 735 fourth port 740 valve member 745 spring 750 electric actuator -15

Claims

CLAIMS1. A lubrication system (600) for an internal combustion engine (110), comprising: -a variable displacement oil pump (605) having an inlet (635), an outlet (640), a primary control chamber (675) and a secondary control chamber (680), wherein the displacement of the oil pump (605) is determined by the pressures in the primary and secondary con-trol chambers (675, 680), -an oil sump (610) connected to the inlet (635) of the oil pump (605), -a main gallery (615) connected to the outlet (640) of the oil pump (605) and to the pri-mary control chamber (675), -a piston cooling jet (700) for cooling a piston (140) of the engine (110), -an auxiliary galler (695) connected to the piston cooling jet (700), and -a control valve (710) having a first port (720) connected to the secondary control cham-ber (680), a second port (725) connected to the auxiliary gallery (695), a third port (730) connected to the main gallery (615), a fourth port (735) connected to the oil sump (610), and a valve member (740) movable between a first position, in which the third port (730) is connected to the second port (725) and contemporaneously the first port (720) is con-nected to the fourth port (735), and a second position, in which the second port (725) is disconnected from the third port (730) and contemporaneously the third port (730) is connected to the first port (720).
2. A lubrication system (600) according to claim 1, wherein the control valve (710) is configured to connect the second port (725) to the fourth port (735) as the valve member (740) is in the second position.
3. A lubrication system (600) according to claim 1 or 2, wherein the control valve (710) comprises an electric actuator (750) to move the valve member (740).
4. A lubrication system (600) according to claim 3, wherein the control valve (710) comprises resilient means (745) to move the valve member (740).
5. A lubrication system (600) according to claim 4, wherein the resilient means (745) are arranged to move the valve member (740) towards the first position, and the electric actuator (750) is arranged to move the valve member (740) towards the second position.
6. A lubrication system (600) according to any of the preceding claims, wherein the piston cooling jet (700) comprises a check valve (705) for selectively opening and closing the piston cooling jet (700).
7. A method for operating a lubrication system (600) according to any of the claims from ito 6, wherein the method comprises the steps of: -monitoring an engine load, -moving the valve member (740) in the first position if the engine load exceeds a prede-termined threshold value, -moving the valve member (740) in the second position if the engine load is below the threshold value.
8. A computer program comprising a computer code suitable for performing the method according to claim 7.
9. A computer program product on which the computer program of claim 7 is stored.
10. An electromagnetic signal modulated as a carrier for a sequence of data bits repre-senting the computer program according to claim 7.