GB2514406A

GB2514406A - Cam cover for a cylinder head of an internal combustion engine

Info

Publication number: GB2514406A
Application number: GB1309325.7A
Authority: GB
Inventors: Roberto Spina; Luigi Di Gennaro
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2013-05-23
Filing date: 2013-05-23
Publication date: 2014-11-26
Also published as: GB201309325D0; CN104179547A

Abstract

A cam cover 600 for covering a cylinder head of an internal combustion engine comprises a structure (605, fig.4) suitable for being associated, in a bottom part thereof, with a camshafts ambient 670 [ie the space between the lower surface of the structure 605 and the seating of the camshafts]. The structure (605) comprises a first chamber 650 having an inlet 510 for an oil-gas mixture from the crankcase and an outlet, eg duct 615, to the camshafts ambient 670 and a second chamber 660 which is separated, eg by a wall 610, from direct communication with the first chamber 650 and which has an inlet, eg hole 620, from the camshafts ambient 670 and outlet (540,560,630) for the collected oil. Oil/gas mixture from the exhaust side may enter the structure via duct 530.

Description

CAM COVER FOR A CYLINDER HEAD OF AN INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD

The present disclosure relates to a cam cover for covering a cylinder head of an internal combustion engine.

BACKGROUND

An internal combustion engine for a motor vehicle generally comprises an engine block which defines at least one cylinder accommodating a reciprocating piston coupled to rotate a crankshaft. The cylinder is closed by a cylinder head that cooperates with the reciprocating piston to define a combustion chamber. A fuel and air mixture is cyclically disposed in the combustion chamber and ignited, thereby generating hot expanding exhaust gasses that cause the reciprocating movements of the piston. The fuel is injected into each cylinder by a respective fuel injector. The fuel is provided at high pressure to each fuel injector from a fuel rail in fluid communication with a high pressure fuel pump that increase the pressure of the fuel received from a fuel source.

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

In th 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, camshafts bearings, valve shafts and other moving metal parts that require lubrication to help avoid excess friction and heat buildup.

: During the operation of the engine, an oil-gas mixture is drawn from the oil sump into a baffle that forms part of a cam cover for covering a cylinder head of an internal combustion engine that operates as an oil separator device. A cam cover is also called ***ee* cylinder head cover in the art.

The baffle forms a U-shaped circuit for the circulation of an oil-gas mixture that is drawn into the baffle through a blow-by duct at the inlet side of the engine, through a blow-by duct from a camshafts ambient and through a blow-by duct at the exhaust side of the engine.

A greater quantity of an oil-gas mixture is drawn through the blow-by duct at the inlet side of the engine because of the direction of rotation of the crankshaft.

The camshafts ambient is the space between the lower portion of the U-shaped baffle and the seating over the cylinder heads of the camshafts that command the opening and closing of the cylinders' valves.

A substantial portion of the oil-gas mixture derives from the blow-by phenomenon that is generated when the explosion that occurs in the engines combustion chamber causes fuel, air and moisture to be forced past sealing rings between piston and cylinder into the crankcase.

A known U-shaped baffle that forms part of a cam cover has a first inlet for the oil-gas mixture in the blow-by duct inlet, a second inlet in the blow-by duct from the camshafts ambient and a third inlet from a blow-by exhaust side duct, these three inlets feeding an U-shaped circuit inside the cam cover and that is interrupted, in a downstream position thereof, by an oil separator.

The oil separator is a filter that is used to collect the oil, for example by virtue of a coalescing phenomenon, in such a way that the collected oil may return, in liquid form, *... 20 via a one-way valve into the oil sump. Another one-way valve is generally provided : * immediately upstream the oil separator because, in that position, part of the oil may be already in liquid form and the one-way valve helps to avoid clogging the circuit.

The air separated from the oil by the oil separator continues through a circuit portion *.*m..

* that terminates in an inlet portion of the engine and mixes with intake air in order to *.**** comply with emissions regulations.

A cam cover, as above described, may not be optimal in case of a high blow-by flow rate produced by the engine, especially by twin stage turbocharged engines.

A consequence of this is an anomalous liquid oil accumulation in the baffle chamber of the device.

The liquid oil so accumulated is then blown off through the peparator by the blow-by flow: the final result is a very low separation efficiency and a very high oil consumption.

An object of an embodiment disclosed is to decrease liquid oil accumulation in the cam cover in order to achieve better separation efficiency and to decrease the blow-by flow velocity.

The overall result is a decrease of the oil carry over amount and, as consequence, of the engine oil consumption.

These objects are achieved by a cam cover for covering a cylinder head of an internal combustion engine that operates separating oil from an oil-gas mixture and by an engine having the features recited in the independent claims.

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

SUMMARY

An embodiment of the invention provides a cam cover for covering a cylinder head of an internal combustion engine. The cam cover comprises a structure which, when mounted in or on an engine is in fluid/flow communication with a camshafts ambient of ": 20 the engine, in particular in a bottom part thereof. The structure comprises a first chamber : ** equipped with an inlet for an oil-gas mixture from a crankcase of the engine and a S...

second chamber equipped with an outlet for the collected oil, the first and second chamber being in flow communication with the camshafts ambient.

* The two flow communications with the camshafts ambient serve to enable a flow of *5*SS* * 25 gas-oil mixture from the first chamber to the camshafts ambient and from there to the second chamber.

An advantage of this embodiment is that, by virtue of the configuration of the device, the oil-gas mixture flows through a lengthy and tortuous path.

Furthermore, since the above embodiment creates a long path for the oil-gas mixture flow, this allows operating properly with high blow-by flow rates such as those created by a twin turbo engine.

This embodiment has improved separation efficiency and reduced oil consumption.

According to another embodiment of the invention, the first chamber and the second chamber are separated by a wall. The wall may extend o'&er the whole height and length of a section of the structure. With the wall there is no direct flow communication between the first chamber and the second chamber or in other words the two chambers are fluidly decoupled or flow-separated as the wall prevents a direct flow of a gas-oil mixture from the first chamber directly to the second chamber completely. The net effect is that 100% of the gas-oil mixture entering the first chamber is channeled to the camshafts ambient instead and from the to the second chamber, such that there is only an indirect flow of oil-gas mixture and thus an indirect coupling of the two chambers via the camshafts ambient.

An advantage of this embodiment is that a single structure in the cam cover can * . 20 provide the tortuous path for the oil-gas mixture.

: ** Another advantage of this embodiment is that it creates a subdivision of the circuit in two chambers and, at the same time, compels the oil-gas mixture to flow through the camshaft ambient. *

*.e.ee * According to a further embodiment of the invention, the first chamber comprises a ****** * 25 duct in communication with the camshafts ambient. The duct is preferably positioned upstream of the wall.

An advantage of this embodiment is that it allows increasing the length of the oil-gas mixture circuit by employing also the space defined by the camshafts ambient.

According to still another embodiment of the invention, the second chamber comprises a hole in flow communication with the camshafts ambient. The hole is preferably positioned downstream of the wall.

An advantage of this embodiment is that it allows the oil-gas mixture to flow back from the camshafts ambient into the second chamber of the circuit.

According to another embodiment of the invention, the second chamber comprises an oil separator An advantage of this embodiment is that the oil separator separates the oil that has not yet separated from the oil-gas mixture in the previous portions of the circuit.

According to another embodiment of the invention, the outlet or the collected oil in the second chamber comprises a one-way valve.

An advantage of this embodiment is that it allows oil that has already separated from the oil-gas mixture to flow back into the oil sump.

A still further aspect of the invention provides an internal combustion engine equipped with a crankcase, a cylinder head, a cam cover for covering the cylinder head, the cam cover being in flow communication, in particular in a bottom part thereof, with a camshafts ambient of the engine, the structure comprising a first chamber equipped with an inlet for an oil-gas mixture from a crankcase of the engine and a second chamber equipped with an outlet for collected oil, the first and second chamber being in flow communication with the camshafts ambient.

The advantages of this embodiment are substantially the same of the device for

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separating oil from the oil-gas mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, wherein like numerals denote like elements, and 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 cam cover according to the prior art; Figure 4 represents a top view of a structure belonging to a cam cover according to an embodiment of the invention; Figure 5 represents a bottom view of the structure of Figure 4; and Figure 6 represents an isometric view of the structure of Figures 4 and 5.

DETAILED DESCRIPTION

Exemplary embodiments will now be described with reference to the enclosed drawings without intent to limit application and uses.

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 Feast one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145, the crankshaft 145 being housed in a crankcase 680. A cylinder head 130 cooperates *:"* 20 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 hat "S.

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 S..

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 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.

A space in which the camshaft 135 is housed is defined as a camshafts ambient 670 (Fig.2).

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 geometryturbine (VGT) with a VOT 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 u.n.

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 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 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.

More specifically, Figure 3 shows a schematic illustration of a cam cover according to the prior art, globally indicated with the reference number 500.

The cam cover 500 comprises an U-shaped structure 505 that is associated with a * : cover 507 of the engine 110 in such a way to form an U-shaped circuit for the oil-gas * 25 mixture.

The mixture enters into said circuit from an engine inlet side blow-by duct 510, from a camshafts ambient 670 by means of a camshafts ambient blow-by duct 520 and from an engine exhaust side blow-by duct 530 These three blow-by ducts feed the U-shaped circuit of the device 500 and said circuit is interrupted, in a downstream position with respect to the three blow-by ducts, by an oil separator 550.

The oil separator 550 is a filtering device that is used to condense the oil, for example by virtue of a coalescing phenomenon.

An oil outlet 540 is provided immediately upstream the oil separator 550 and a second oil outlet 560 is provided downstream of the oil separator 550, so that the collected oil may return, in liquid form, into the oil sump in the crankcase 680. Both oil oytlets 540,560 comprise each a one-way valve. -Figures 4-6 represents a structure belonging to a cam cover according to an embodiment of the invention.

Similar components with respect to the device of Figure 3 are indicated with the same numerals.

The cam cover is globally indicated with the reference numeral 600 and, in an embodiment of the invention, comprises an U-shaped structure 605 that is associated with a cover (not represented for simplicity), in such a way to form a circuit for the oil-gas mixture.

The cam cover 600 is mounted over a camshafts ambient 670, namely the space : *". between the lower surface of the U-shaped structUre 605 and the seating of the camshafts over the cylinder heads.

The U-shaped structure 605 is provided with a wall 610, positioned downstream of a duct 615 that leads into the camshafts ambient 670, and that extends over the whole height and length of a section of the U-shaped structure, in order to deviate the flow of the oil-gas mixture in that position.

The wall 610 subdivides the circuit formed by the structure 605 into a first chamber 650, that may operate as a pre-separation chamber, and a second chamber 660 that is connected to the oil separator 550.

Downstream of the wall 610, a hole 620 is provided that connects the camshafts ambient 670 to the second chamber 660.

In operation, the oil-gas mixture enters into the circuit from the crankcase 680 of the engine 110 through the engine inlet side blow-by duct 510 and flows through the first chamber 650 until it reaches the duct 615 to the camshafts ambient 670.

Due to the presence of the wall 610, the oil-gas mixture then flows into the camshafts ambient 670 and, from such ambient, flows back into the cam cover 600 by entering the second chamber 660 through the hole 620 connecting the camshafts ambient 670 to the second chamber 660.

A smaller quantity of the oil-gas mixture may flow into the second chamber 660 through the engine exhaust side blow-by duct 530.

In the second chamber 660, part of the oil present in the oil-gas mixture is collected and the collected oil may flow back into the oil sump in the crankcase 680 through the oil outlet 540 and oil outlet 630 upstream the oil separator 550.

Furthermore, the oil-gas mixture is drawn into the oil separator 550 that performs its oil separation function, and the collected oil flows back into the oil sump in the crankcase 680 through oil outlet 560. Oil outlets540,560 and 630 comprise each a one-way valve.

Finally, the residual gas flows back into the inlet manifold of the engine 110.

By virtue of the configuration of the cam cover 600, the oil-gas mixture flows through *....: 25 a long and tortuous path.

This allows for improved separation efficiency and reduced oil consumption.

In general, the cam cover 600, according to the various embodiments of the invention, can be configured as comprising a structure 605 suitable for being associated, in a bottom part thereof, with a camshafts ambient 670 of the engine 110.

The structure 605 may comprise one or more parts that, when mounted in the cam cover 600, form a first chamber 650 equipped with an inlet 510 for the oil-gas mixture from the crankcase 680 of the engine 110 and a second chamber 660 equipped with an outlet 540,560,630 for the collected oil in such a way that the first and second chamber 650,660 are in communication with the camshafts ambient 670.

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. * . .

* * 20 -* . * .. *1 * **** * * *

S * S

REFERENCE NUMBERS

automotive system internal combustion engine (ICE) engine block 125 cylinder cylinder head camshaft piston crankshaft 150 combustion chamber cam phaser fuel injector fuel rail fuel pump 190 fuel source intake manifold 205 air intake duct 210 intake air port 215 valves of the cylinder :e.: 20 22Oexhaustgasport * 225 exhaust manifold : *". 230 turbocharger 240 compressor 250 turbine * *..: 25 260 intercooler 270 exhaust system 275 exhaust pipe 280 exhaust aftertreatment device 290 VGT actuator 300 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 senspr 430 exhaust pressure and temperature sensor 445 accelerator pedal position sensor 450 electronic control unit (ECU) 460 data carrier 20 Soocamcover(priorart) * 505 U-shaped structure : *. 507 cover of the engine 510 engine inlet side blow-by duct 520 camshafts ambient blow-by duct *** * * 530 engine exhaust side blow-by duct 540 oil outlet upstream oil separator 550 oil separator 560 oil outlet downstream oil separator 600 cam cover 605 U-shaped structure 610 wall 615 duct to the camshafts ambient 620 hoLe from camshafts ambient 630 oil outlet upstream oil separator 650 first chamber 660 second chamber 670 camshafts ambient 680 crankcase -S. * S S * S

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50e5S5 * S * S. * S S...

*5555. * S

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Claims

CLAIMS1. A cam cover (600) for covering a cylinder head (130) of an internal combustion engine (110), the cam cover (600) comprising a structure (605) which, when mounted in the engine, is in flow communication with a camshafts ambient (670) of the engine (110), the structure (605) comprising a first chamber (650) equipped with an inlet (510) for an oil-gas mixture from a crankcase (680) of the engine (110) and a second chamber (660) equipped with an outlet (540,560,630) for collected oil, the first and second chamber (650,660) being in flow communication with the camshafts ambient (670).
2. A cam cover (600) according to claim 1, wherein the first chamber (650) and the second chamber (660) are separated by a wall (610).
3. A cam cover (600) according to claim 2, wherein the first chamber (650) comprises a duct (615) to the camshafts ambient (615).
4. A cam cover (600) according to claim 2, wherein the second chamber (660) comprises a hole (620) in communication with the camshafts ambient (670).
5. A cam cover (600) according to claim 1, wherein the second chamber (660) comprises an oil separator (550).
6. A cam cover (600) according to claim 5, wherein the outlet (540,560,630) for the collected oil in the second chamber (660) comprises a one-way valve (540). S. *e * . .* * 20
7. An internal combustion engine (110) equipped with a crankcase (680), a cylinder head (130), a cam cover (600) for covering the cylinder head (130), the cam cover (600) comprising a structure (605) being in flow communication, in particular in a bottom part thereof, with a camshafts ambient (670), the structure (605) comprising a first chamber (650) equipped with an inlet (510) for an oil-gas mixture from a crankcase (680) and a second chamber (660) equipped with an outlet (540,560,630) for collected oil, the first-Jand second chamber (650660) being in flow communication with the camshafts ambient (670). * a a *a..... * . * a. * * a a... a * . * a