GB2521807A

GB2521807A - Lubrication system for an internal combustion engine

Info

Publication number: GB2521807A
Application number: GB1318131.8A
Authority: GB
Inventors: Giorgio Candela
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2013-10-14
Filing date: 2013-10-14
Publication date: 2015-07-08
Anticipated expiration: 2033-10-14
Also published as: GB2521807B; GB201318131D0

Abstract

A lubrication system 1 for an internal combustion engine (fig 1, 110), the engine comprising an engine block (fig 1, 120), a cylinder head (fig 1, 130), the lubrication system comprising an oil pump 2 for circulating a lubricant in the 5 lubrication system, an oil filter 4, located downstream and in fluid connection with the oil pump, for cleaning the lubricant, a main gallery 5 located in the engine block (fig 1, 120) and in fluid connection with the oil filter, for distributing the lubricant in engine components located in the cylinder block, a head gallery 6 located in the cylinder head (fig 1, 130) and in fluid connection with the main gallery, for distributing the lubricant in engine components located in the cylinder head, an oil pan 8, for collecting the lubricant from the main and the head gallery and from which the oil pump is fed, a relief valve 7 for controlling an oil pressure in the lubrication system, wherein said relief valve 7 is in fluid connection between the main gallery and an oil pump inlet 2'. The lubrication system may also include an oil cooler 3 for cooling the lubricant and a plurality of cooling jets 9 for engine piston (fig 1, 140).

Description

LUBRICATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD

The present disclosure relates to a lubrication system for an internal combustion engine.

In particular, the invention is suitable for lubrication systems provided with a mechanical relief valve, which limits the oil pump pressure.

BACKGROUND

The importance of proper lubrication is obvious, as the majority of operating problems and damage to internal combustion engines are caused by improper lubrication control. The lube oil forms a film around the shafts, separating the shafts and bearings to prevent metal-to-metal contact, thus reducing friction and preventing wear of the bearing metal. The heat due to friction in large bearings can be considerable, and large quantities of oil have to be circulated through the bearings for temperature control.

Typical lubrication systems are a forced-feed system of lubrication and uses the oil contained in the oil pan as a reservoir. A gear type oil pump is driven from the crankshaft The oil enters the pump and is canled around the pump casing by the gear teeth. It is then discharged. The oil is prevented from returning to the inlet by the meshing of the gear teeth. Oil is pumped from the oil pan through an oil filter and cooler into the lubricating oil manifold, which is normally called main gallery and is located into the engine block. A fluid connection brings the oil also in the cylinder head where a head gallery is located.

The pressure control of a lubrication system is very important. In particular, a too high oil pressure should be avoided and normally the lubrication system is provided with a relief valve, which limits the oil pressure at a given threshold. A high oil pressure can be due to high oil viscosity, the relief valve set too high, or blockages. When the engine is cold, the oil pressure is higher than normal, but it should not be excessive. Excessive pressure can rupture oil filters and even wash out bearings if allowed to continue for extended periods of time.

Lubrication circuit architecture in ICE is normally designed with a relief valve, which is located immediately downstream of the oil pump. The reason is to protect the oil cooler and the oil filter from a too high pressure. This kind of architecture does not allow to control the pressure in the main gallery. This could lead to a pressure reduction and consequently to a possible engine seizure in case of leakage from components (for example, oil cooler and oil filter) placed upstream to the cylinder block main gallery.

Therefore a need exists for a new lubrication system architecture which avoids the above mentioned inconvenience.

An object of an embodiment of the invention is to provide a lubrication system for internal combustion engines, whose architecture ensures not to have a too low pressure in the main gallery.

These objects are achieved by a lubrication system and by an engine having the features recited in the independent claims.

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

SUMMARY

An embodiment of the disclosure provides a lubrication system for an internal combustion engine, the engine comprising an engine block, a cylinder head, the lubrication system comprising an oil pump for circulating a lubricant in the lubrication system, an oil filter, located downstream and in fluid connection with the oil pump, for cleaning the lubricant, a main gallery located in the engine block and in fluid connection with the oil filter, for distributing the lubricant in engine components located in the cylinder block, a head gallery located in the cylinder head and in fluid connection with the main gallery, for distributing the lubricant in engine components located in the cylinder head, an oil pan for collecting the lubricant from the main and the head gallery and from which the oil pump is fed, a relief valve for controlling an oil pressure in the lubrication system, wherein said relief valve is in fluid connection between the main gallery and an oil pump inlet.

An advantage of this embodiment is that being the relief valve connected to the cylinder block main gallery, it is possible to keep the oil pressure value constant avoiding too high pressures that can damage sealing features and lube circuit components, but also too low pressures, which can cause seizure to the engine components, the low pressure being due to leakages from components upstream the relief valve.

According to another embodiment, the oil pump is a volumetric gear pump and the relief valve is a mechanical valve.

An advantage of this embodiment is that the oil pressure provided by the volumetric gear pump only depends on the calibrated opening pressure of the relief valve, located downstream the pump outlet, and that a mechanical relief valve has a preloaded spring that opens at a defined oil pressure discharging partially the circuit to maintain a constant pressure upstream the valve.

According to a further embodiment, the oil pump is an internal gear pump comprising two eccentric inner gears.

An advantage of this embodiment is that such kind of gear pumps, for example the so called "Gerotors", are widely used today throughout industry, and are produced in a variety of shapes and sizes by a number of different methods.

According to still another embodiment, the oil pump is an external gear pump.

An advantage of this embodiment is that extemal gear pumps work according to a well-known pumping principle and are often used as lubrication pumps in machine tools, in fluid power transfer units, and as oil pumps in engines.

According to a still further embodiment, the lubrication system also comprises an oil cooler for cooling the lubricant and located downstream the oil pump and upstream the oil filter and in fluid connection with both the oil pump and the oil filter.

An advantage of this embodiment is that the present architecture of the lubrication system, with the relief valve located downstream the oil cooler, prevents too low oil pressure due to leakages in the oil cooler.

According to still another embodiment, the lubrication system also comprises a plurality of piston cooling jets for engine pistons cooling and in fluid connection with the main gallery.

An advantage of this embodiment is that the lubrication system also comprises piston cooling jets to keep under control the piston temperature.

Another embodiment of the disclosure provides an internal combustion engine comprising an engine block, a cylinder head and a lubrication system according to any of the preceding embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an automotive system.

Figure 2 is a section of an internal combustion engine belonging to the automotive system of figure 1.

Figure 3 is a scheme of a lubrication system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Some embodiments may include an automotive system 100, as shown in Figures 1 and 2, that includes an intemal 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 125 has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200.

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

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. 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 andlor devices associated with the ICE 110 and equipped with a data carrier 40. 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, pressure, 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 waste gate 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.

According to an embodiment of the present invention, as shown in Fig. 3, the lubrication system 1 comprises an oil pump 2 for circulating a lubricant in the lubrication system, an oil filter 4, located downstream and in fluid connection with the oil pump, for cleaning the lubricant, a main gallery 5 located in the engine block 120 and in fluid connection with the oil filter for distributing the lubricant in engine components located in the cylinder block, a head gallery 6 located in the cylinder head 130 and in fluid connection with the main gallery, for distributing the lubricant in engine components located in the cylinder head, an oil pan 8, for collecting the lubricant from the main and the head gallery and from which the oil pump is fed, a relief valve 7 for controlling an oil pressure in the lubrication system, wherein said relief valve 7 is in fluid connection between the main gallery and an oil pump inlet 2'. Being the relief valve connected to the cylinder block main gallery, it is possible to keep the oil pressure value constant avoiding too high pressures that can damage sealing features and lube circuit components, but also too low pressures, due to leakages from components upstream the relief valve, which can cause seizure to the engine components. The relief valve can be located downstream the oil filter, since this valve normally opens at about 0,9 MPa, while the oil filter, according to several test results, can be used up to 2.5 MPa, without suffering any leakages.

Preferably, the oil pump 2 is a volumetric gear pump and the relief valve 7 is a mechanical valve. As known, a gear pump uses the meshing of gears to pump fluid by displacement. They are one of the most common types of pumps for hydraulic fluid power applications. Gear pumps are positive displacement (or fixed displacement), meaning they pump a constant amount of fluid for each revolution. The oil pressure provided by the volumetric gear pump only depends on the calibrated opening pressure of the relief valve, located downstream the pump outlet. Furthermore, a mechanical relief valve has a preloaded spring that opens at a defined oil pressure discharging partially the circuit to maintain a constant pressure upstream the valve. Therefore, using a gear pump and a mechanical relief valve makes easier to keep a constant oil pressure in the main gallery.

For example, the gear pump can comprise two eccentric inner gears. Intemal gear pumps are exceptionally versatile. In addition to their wide viscosity range, the pump has a wide temperature range as well. The internal gear pump is non-pulsing, self-priming, and can run dry for short periods. Because internal gear pumps have only two moving parts, they are reliable, simple to operate, and easy to maintain. An internal gear pump is also called Gerotor". The name is derived from "Generated Rotor". A "Gerotor" unit consists of an inner and outer rotor. The inner rotor has N teeth, and the outer rotor has Nil teeth. The inner rotor is located off-center and both rotors rotate. The geometry of the two rotors partitions the volume between them into N different dynamically-changing volumes. During the assembly's rotation cycle, each of these volumes changes continuously, so any given volume first increases, and then decreases. An increase creates a vacuum. This vacuum creates suction, and hence, this part of the cycle is where the intake is located. As a volume decreases compression occurs. During this compression period, fluids can be pumped, or compressed (if they are gaseous fluids).

"Gerotor" pumps are generally designed using a trochoidal inner rotor and an outer rotor formed by a circle with intersecting circular arcs.

According to another example the oil pump 2 is an external gear pump. External gear pumps work according to a well-known pumping principle and are often used as lubrication pumps in machine tools, in fluid power transfer units, and as oil pumps in engines. External gear pumps can come in single or double (two sets of gears) pump configurations with spur, helical, and herringbone gears. Helical and herringbone gears typically offer a smoother flow than spur gears, although all gear types are relatively smooth. External gear pumps have close tolerances and shaft support on both sides of the gears. This allows them to run to pressures beyond 20 MPa, making them well suited for use in hydraulics. With four bearings in the liquid and tight tolerances, they are not well suited to handling abrasive or extreme high temperature applications.

Preferably, the lubrication system 1 also comprises an oil cooler 3, for cooling the lubricant and located downstream the oil pump and upstream the oil filter and in fluid connection with both the oil pump and the oil filter. In this way, the present architecture of the lubrication system, with the relief valve located downstream the oil cooler, prevents too low oil pressure due to leakages in the oil cooler. The relief valve can be located downstream the oil cooler, since this valve normally opens at about 0,9 MPa, while the oil cooler, according to several test results, can be used up to 2.5 MPa, without suffering any leakages.

The lubrication system 1 can also comprise a plurality of piston cooling jets 9, for engine pistons 140 cooling, in fluid connection with the main gallery 5.

Summarizing, this circuit architecture is able to protect the main gallery pressure, guaranteeing the desired oil pressure value on the crankshaft main bearings and on other engine block components, even if some component upstream the main gallery has a small oil leakage (namely, oil cooler and oil filter). By this way the engine reliability is significantly increased. No extra components are required with respect to known lubrication system architectures.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS

1 lubrication system 2 oilpump 2' oil pump inlet 3 oil cooler 4 oil filter main gallery 6 head gallery 7 relief valve 8 oil pan 9 piston cooling jets data carrier automotive system 110 internal combustion engine engine block cylinder cylinder head camshaft 140 piston crankshaft combustion chamber cam phaser fuel injector 165 fuel injection system fuel rail fuel pump fuel source intake manifold 205 air intake duct 210 intake port 215 valves 220 port 225 exhaust manifold 230 turbocharger 240 compressor 245 turbocharger shaft 250 turbine 260 intercooler 270 exhaust system 275 exhaust pipe 280 aftertreatment devices 290 waste gate valve 295 waste gate actuator or electric pressure valve or boost pressure control valve 300 exhaust gas recirculation system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow, pressure, temperature and humidity sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant temperature and level sensors 385 lubricating oil temperature and level sensor 390 metal temperature sensor 400 fuel rail digital pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensors 440 EGR temperature sensor 445 accelerator position sensor 446 accelerator pedal 450 ECU

Claims

CLAIMS1. Lubrication system (I) for an internal combustion engine (110), the engine comprising an engine block (120), a cylinder head (130), the lubrication system comprising an oil pump (2) for circulating a lubricant in the lubrication system, an oil filter (4), located downstream and in fluid connection with the oil pump, for cleaning the lubricant, a main gallery (5) located in the engine block (120) and in fluid connection with the oil filter for distributing the lubricant in engine components located in the cylinder block, a head gallery (6) located in the cylinder head (130) and in fluid connection with the main gallery, for distributing the lubricant in engine components located in the cylinder head, an oil pan (8), for collecting the lubricant from the main and the head gallery and from which the oil pump is fed, a relief valve (7) for controlling an oil pressure in the lubrication system, wherein said relief valve (7) is in fluid connection between the main gallery and an oil pump inlet (2').
2. Lubrication system (1) according to claim 1, wherein the oil pump (2) is a volumetric gear pump and the relief valve (7) is a mechanical valve.
3. Lubrication system (1) according to claim 2, wherein the oil pump (2) is an internal gear pump comprising two eccentric inner gears.
4. Lubrication system (1) according to claim 2, wherein the oil pump (2) is an external gear pump.
5. Lubrication system (1) according to any of the preceding claims, wherein it also comprises an oil cooler (3) for cooling the lubricant and located downstream the oil pump and upstream the oil filter and in fluid connection with both the oil pump and the oil filter.
6. Lubrication system (1) according to any of the preceding claims, wherein it also comprises a plurality of piston cooling jets (9) for engine pistons (140) cooling and in fluid connection with the main gallery (5).
7. Internal combustion engine (110) comprising an engine block (120). a cylinder head (130) and a lubrication system (1) according to any of the preceding claims.