Patent Application
20110253092
This application claims priority to German Patent Application Serial Number 10 2010 027 816.5, titled “INTERNAL COMBUSTION ENGINE WITH OIL CIRCUIT AND METHOD FOR HEATING THE ENGINE OIL OF AN INTERNAL COMBUSTION ENGINE OF SAID TYPE” and filed on Apr. 15, 2010, the entire disclosure of which is hereby incorporated by reference for all purposes.
The present description relates to a system for heating engine oil.
Friction in lubricated engine bearings, such as camshaft bearings, contributes to a vehicle's fuel economy. The friction depends, at least in part, on engine oil viscosity, which is a function of engine oil temperature. Thus, the temperature of the engine oil contributes to the fuel consumption and emissions of the internal combustion engine.
Oil systems may be provided where oil is drawn from a sump and provided to various engine components before being returned to the sump. While various approaches, such as electric heaters and other waste heat recovery mechanisms may be used to provide increased heat to the oil, the inventors herein have recognized that there is still a delay in heating up all of the oil in the system so that sufficiently heated oil is drawn from the sump and delivered to the engine components for lubrication.
As described herein, one approach to address the above issues includes supplying engine oil from a higher pressure oil pump side to reciprocating engine components, where at a first condition, at least some engine oil downstream of the reciprocating engine components is diverted around an oil sump to a lower pressure oil pump side via a bypass line. Further, at a second condition, engine oil downstream of the reciprocating engine components may be routed to the oil sump, for example in a path separate from the bypass line.
In this way, it is possible to provide the available engine heat and friction heat from the engine components to a smaller volume of oil, where that smaller volume of oil is preferentially used as compared to colder oil in the sump. As such, the oil actually provided to the engine components heats up more rapidly for a given amount of heat input, whether from friction, waste heat recovery, electric heater, and the like, which may be used, if desired. Then, once sufficient warm-up has occurred where substantially all of the engine oil, including oil in the sump, has reached a desired operating temperature, the bypass oil line may be disabled. As such, during over-temperature conditions, the full oil supply is available to reduce oil over-heating.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
An internal combustion engine may be used as a drive for motor vehicles. Within the context of the present disclosure, “internal combustion engine” encompasses diesel engines, spark-ignition engines, and hybrid internal combustion engines (e.g., an internal combustion engine operated with a hybrid combustion process). In some embodiments, the engine may be coupled to an electric motor/battery system in a hybrid vehicle. Non-limiting examples of hybrid vehicles may have a parallel configuration, a series configuration, or any suitable variation or combination thereof.
Internal combustion engines have a cylinder block and a cylinder head that are united to form a cylinder for combusting fuel. Referring to
During operation of engine 10, combustion chamber 30 is charged with air and fuel, burns the fuel, and discharges exhaust gas. Valves are generally used to control the charge exchange. Typically, such valves are movable along their longitudinal axis between a closed position and an open position to open and shut an inlet or outlet opening. In one non-limiting example, valves include valve springs that are preloaded in the direction of the closed position and valve actuating devices, or cams, which open the valves against the preload of the valve springs. The valve actuating devices generally comprise one or more camshafts on which a plurality of cams is arranged. The camshafts are rotated by a drive from crankshaft 40. In one non-limiting example, a camshaft may be rotated by a chain drive.
In some embodiments, overhead camshafts may be included in engine 10. Overhead camshafts are mounted in the cylinder head and are arranged above the assembly surface between the cylinder head and cylinder block. Overhead camshafts are often mounted in two-part camshaft receptacles. For this purpose, the overhead camshaft has at least two bearing points, which are generally formed as thickened shaft shoulders.
As shown in
Generally, an upper crankcase is formed by the cylinder block, and is complemented by a lower crankcase, which may be mounted on the upper crankcase by screws, bolts, or other suitable connectors. The lower crankcase may include an oil collection sump, such as an oil pan. In some embodiments, the upper crankcase may include a flange surface to hold the oil sump and a seal to seal off the oil sump or the crankcase with respect to the environment.
The oil sump collects and stores the engine oil and is part of the lubricating system. Furthermore, the oil sump may act as a heat exchanger, reducing the oil temperature when the internal combustion engine is at operating temperature. For example, the oil in the oil sump may be cooled by conduction and/or by convection of heat to a heat sink and/or to air conducted over the outside of the oil sump.
Fuel injector 66 is shown positioned to inject fuel directly into combustion chamber 30, which is known to those skilled in the art as direct injection. Alternatively, fuel may be injected to an intake port, which is known to those skilled in the art as port injection. Fuel injector 66 delivers liquid fuel in proportion to the pulse width of signal FPW from controller 12. Fuel is delivered to fuel injector 66 by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). Fuel injector 66 is supplied operating current from driver 68 that responds to controller 12. In addition, intake manifold 44 is shown communicating with optional electronic throttle 62. Electronic throttle 62 adjusts a position of throttle plate 64 to control airflow from air intake 42 to intake manifold 44. In one example, a low-pressure direct injection system may be used, where fuel pressure can be raised to approximately 20-30 bar. Alternatively, a high pressure, dual stage, fuel system may be used to generate higher fuel pressures.
Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12.
The heat released into the cylinder head during the combustion is dissipated partially to the cylinder head and the cylinder block and partially to the adjacent components and the environment via the exhaust gases. Cooling system 150 is included to manage heat loads within engine 10. The cylinder head may be equipped with a coolant jacket or cooling sleeve 114, which may be at least partially integrated in the cylinder head via coolant ducts. In some embodiments, cooling system 150 may be a water cooling system. For example, in the embodiment shown in
Universal Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 126. Converter 70 can include multiple catalyst bricks, in one example. In another example, multiple emission control devices, each with multiple bricks, can be used. Converter 70 can be a three-way type catalyst in one example.
Controller 12 is shown in
Controller 12 is shown receiving various signals from sensors coupled to engine 10, in addition to those signals previously discussed, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; a position sensor 134 coupled to an accelerator pedal 130 for sensing force applied by foot 132; a measurement of engine manifold pressure (MAP) from pressure sensor 122 coupled to intake manifold 44; an engine position sensor from a Hall effect sensor 118 sensing crankshaft 40 position; a measurement of air mass entering the engine from sensor 120; and a measurement of throttle position from sensor 58. Barometric pressure, engine oil temperature, engine oil pressure, etc. may also be sensed (sensors not shown) for processing by controller 12.
In one embodiment, engine position sensor 118 produces a predetermined number of equally spaced pulses every revolution of the crankshaft from which engine speed (RPM) can be determined.
In one embodiment, the stop/start crank position sensor has both zero speed and bi-directional capability. In some applications, a bi-directional Hall sensor may be used.
In other applications, magnets may be mounted to the target. Magnets may be placed on the target and the “missing tooth gap” can potentially be eliminated if the sensor is capable of detecting a change in signal amplitude (e.g., using a stronger or weaker magnet to locate a specific position on the wheel). Further, by using a bi-directional Hall sensor or an equivalent, the engine position may be maintained through shut-down, but an alternative strategy may be used during re-start to assure that the engine is rotating in a forward direction.
During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle. The cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. Generally, exhaust valve 54 closes and intake valve 52 opens during the intake stroke. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position at which piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g. when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC).
During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g. when combustion chamber 30 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). Fuel is introduced into combustion chamber 30 in a process hereinafter referred to as injection. In a process hereinafter referred to as ignition, the injected fuel is ignited by a suitable ignition source, such as spark plug 92, resulting in combustion.
During the expansion stroke, the expanding combustion gases push piston 36 back to BDC. Piston 36 transmits the forces generated by the expanding gases to crankshaft 40. For this purpose, piston 36 is articulately connected to a connecting rod by a piston pin, the connecting rod being movably mounted on crankshaft 40. Crankshaft 40 (which is mounted in a crankcase) absorbs the connecting rod forces, including the forces resulting from combustion and the mass forces resulting from non-uniform movement of the engine parts. The oscillating stroke movement of piston 36 is transformed into a rotational movement of crankshaft 40. Thus, crankshaft 40 converts linear piston movement into a rotational torque.
Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture into exhaust manifold 48 and piston 36 returns to TDC. Note that the above is provide merely as an example, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other attributes associated with the operation of engine 10.
Crankshaft 40 transmits the rotational torque to the drivetrain. In some embodiments, a portion of the energy transmitted to crankshaft 40 also drives auxiliary units (e.g., oil pumps, alternators, etc.) and/or drives a camshaft to actuate a valve drive. In some embodiments, the camshaft may be mounted in the cylinder head as an overhead camshaft.
Crankshaft 40 is mounted with one or more crankshaft journals. The crankshaft journals may be spaced apart from one another along a crankshaft axis. In some embodiments, the crankshaft journals may be formed as thickened shaft shoulders. To hold and mount crankshaft 40, at least two bearings are provided in the crankcase. In some embodiments, such bearings may be of a two-part design, comprising a bearing saddle and a bearing cover connected to the bearing saddle. In one example, bearing covers and bearing saddles may be formed as separate components. In another example, the bearing covers and bearing saddles may be integrated into upper and a lower crankcase portions that are later joined to form the crankcase. Complementary pairs of bearing saddles and bearing covers are assembled to form bores for holding the crankshaft journals. In some embodiments, bearing shells may be arranged as intermediate elements between the crankshaft and the bearings. Similar to a plain bearing, the bores are supplied with engine oil to form a load-bearing lubricating film between an inner surface of each bore and the associated crankshaft journal.
To supply consumers 214 with oil, oil pump 208 feeds engine oil to the bearings via one or more delivery conduits or supply lines 212 and a main oil gallery 220, from which ducts 222 lead to consumers 214. Downstream of consumers 214, return lines 238 conduct the engine oil to oil sump 206 for reuse. As shown in
Oil pump 208 is supplied with engine oil from oil sump 206 via a suction line 210. Oil pump 208 draws engine oil through suction line 210 at a lower pressure, expelling engine oil via supply line 212 at a higher pressure. In some embodiments, oil pump 208 may be sized to provide an application-specific engine oil volume and/or engine oil pressure in supply line 212.
As depicted in the embodiment shown in
As shown in
Typically, supply line 212 leads from oil pump 208 through the cylinder block to main oil gallery 220. In some embodiments, main oil gallery 220 is formed at least in part by a main supply duct aligned along a longitudinal axis of crankshaft 40. The main supply duct may be arranged above or below crankshaft 40 in the crankcase or may be integrated into crankshaft 40.
As depicted in
In some embodiments, supply line 212 leads engine oil first through the cylinder block before supply line 212 enters the cylinder head. In such embodiments, the engine oil is heated as it passes through the cylinder block, so that cylinder head side 202 of the oil circuit is supplied with engine oil that has been heated in the cylinder block. Engine oil is further heated in cylinder head side 202 of oil delivery system 200. For example, after a period of standstill of the vehicle, such as during a restart of internal combustion engine 10, engine oil flows through the cylinder block, where it is heated. The heated oil is subsequently heated further in the cylinder head, which reaches high temperatures more quickly because of the combustion processes. Thus, the heating of engine oil may be more pronounced than it would be if engine oil were to flow through the cylinder block alone.
Alternatively, in some embodiments, supply line 212 of oil delivery system 200 may pass first through the cylinder head before supply line 212 enters the cylinder block. For example, in the case of low outside temperatures, heating of the oil may be assisted by a faster heating cylinder head. This effect may be more pronounced if additional optional features are included in engine 10. For example, the integration of exhaust manifold 48 into the cylinder head may assist engine oil heating in the cylinder head, as explained in more detail below.
In some embodiments, supply line 212 comprises at least two partial supply lines extending through the cylinder head. This may increase the surface area available for heat exchange with the engine oil within the cylinder head. Partial supply lines may subsequently merge to reform supply line 212 within or downstream of the cylinder head.
For example, in the embodiment shown in
In some embodiments, engine 10 may include at least two cylinders, each having at least one exhaust port joined to an exhaust line, with the exhaust lines of at least two cylinders merging to form exhaust manifold 48. In some embodiments, the exhaust gases may be supplied to a turbocharger and/or to one or more exhaust-gas after-treatment systems downstream of exhaust manifold 48.
For example, one or more turbochargers may be located close to exhaust manifold 48. Locating the turbocharger close to exhaust manifold 48 may provide a faster response at the turbocharger compared to a more distant location because the enthalpy of the exhaust gas is a function of pressure and temperature, which typically diminish as distance from exhaust manifold 48 increases. In another example, exhaust gas treatment systems may be located close to exhaust manifold 48 so that the exhaust-gas treatment systems, supplied with heat from the exhaust gases, may reach operating, activation, or light-off temperatures faster compared to more distant locations. Thus, it will be appreciated that one approach to achieving faster response and activation times from turbochargers and treatment systems may be directed at reducing the mass and the length of the exhaust line, which may reduce a thermal inertia of the exhaust line.
For example, in some embodiments, the exhaust lines may be merged within the cylinder head to form an integrated exhaust manifold. Integrated exhaust manifolds may provide comparatively more compact packaging of the exhaust lines relative to an external exhaust manifold system. In one scenario with a cylinder head having four cylinders in an in-line arrangement, the exhaust lines of the outer cylinders and the exhaust lines of the inner cylinders may merge into one exhaust line. It will be appreciated that a similar approach may be employed, for example, with cylinder heads having three or more cylinders, in which the exhaust lines of two of the three cylinders merge to form an overall exhaust line.
Cylinder heads having an integrated exhaust manifold typically experience higher heat loads than cylinder heads with external exhaust manifolds. Thus, in some embodiments, heating engine oil in a cylinder head that includes an integrated exhaust manifold may contribute to a further reduction in the friction losses of engine 10. For example, during a warm-up condition after a cold start of engine 10, a cylinder head with an integrated exhaust manifold may reach higher temperatures more quickly compared to a cylinder head with an external manifold. Thus, engine oil conducted through the cylinder head having an integrated exhaust manifold may be heated relatively more quickly.
Because a cylinder head with an integrated exhaust manifold may experience a higher heat load than a cylinder head with an external manifold, cooling system 150 may assist in controlling and/or limiting an upward temperature rise of the engine oil in some conditions.
In other conditions, engine 10 may heat the coolant in cooling system 150 faster than the engine oil is heated. Under such conditions, cooling system 150 may be configured to transfer heat to the engine oil. For example, during a warm-up condition, heat from the coolant may be used to heat the engine oil at a heat exchanger, such as oil cooler 218. Thus, it will be appreciated that the heat transfer between the cylinder head and the engine oil situated in the supply line may comprise the introduction of heat into, or extraction of heat from, the engine oil by cooling system 150 in addition to the introduction of heat from hot exhaust gases.
In some embodiments, cooling sleeve 114 may extend at least partially between the at least two partial supply lines. For example, cooling sleeve 114 may be configured to intersect an imaginary boundary encompassing the at least two partial supply lines. As such, the coolant within cooling sleeve 114 may assist in managing heat transfer to the engine oil. This may offset overheating and/or aging of the engine oil. Further, such approaches may mitigate coking processes in the engine oil, potentially reducing the formation of deposits and/or blockages in supply line 212, the partial supply lines, etc.
Having been heated, engine oil is supplied to consumers 214 via supply line 212. Consumers 214 in the cylinder block include bearings for connecting rods 224, including crankshaft-side connecting rod bearings 226 and piston-side connecting rod bearings 232 and one or more crankshaft bearings. In some embodiments, engine oil may be conducted downstream of oil pump 208 first to main oil gallery 220 to supply engine oil to crankshaft bearings before engine oil flows to the cylinder head.
Consumers 214 in the cylinder head comprise camshaft bearings 230 included within camshaft receptacles 228, though it will be appreciated that other suitable consumers 214 may be included in some embodiments. Camshaft bearings 230 are supplied with engine oil such that a load-bearing lubricating film is formed as the camshaft rotates. Supplying heated engine oil to the camshaft bearings 230 via supply line 212 may reduce the friction in the bearings of the camshaft and consequently may reduce friction losses in engine 10.
The camshaft may be mounted similarly to the above-described crankshaft mounting approach. For example, in some embodiments employing overhead camshafts, camshaft receptacles 228 may have a two-part construction. A two-part camshaft receptacle comprises a lower part and an upper part in which the bearing saddles and bearing covers are arranged. The overhead camshaft is held and mounted with its bearing points in the bearing saddles and bearing covers. In such embodiments, supply line 212 is connected to the two-part camshaft receptacle.
Accordingly, camshaft receptacle 228 is supplied with engine oil via supply line 212, which branches from main oil gallery 220, extends through the cylinder block, and, in some embodiments including overhead camshafts, extends into the cylinder head. Additionally or alternatively, in some embodiments, supply line 212 may lead from the pump directly into the cylinder head, supplying engine oil to camshaft receptacle 228 upstream of main oil gallery 220. It will be appreciated that these approaches apply to both an inlet-side camshaft and to an outlet-side camshaft.
In some embodiments, consumers 214 may also include various valve drive components, such as a hydraulically-actuated camshaft adjuster.
In some embodiments, consumers 214 may be supplied with engine oil on a regular, but not a continuous, basis. For example, if a bearing engine oil supply interacts with a different engine oil supply (for example, via main oil gallery 220), continuously supplying oil to the bearings may disturb the engine oil pressure in oil delivery system 200. Thus, a regular, but not continuous, oil supply to the bearings may be employed in such embodiments.
After the engine oil is supplied to consumers 214, engine oil returns to oil sump 206 via return lines 238 passing through the cylinder head and/or through the cylinder block. Generally, engine oil in a return line 238 is at a lower pressure than engine oil upstream of return line 238. In some embodiments, flow of engine oil through return lines 238 is gravity-driven.
As shown in
Because the engine oil diverted through bypass line 236 avoids the cooling effect at oil sump 206, the engine oil may have a higher temperature than that of engine oil supply 252. Accordingly, reintroducing the heated engine oil to the inlet of oil pump 208 may increase the engine oil throughput in oil delivery system 200 after a cold start. With the increased throughput, the flow rate of the engine oil may also increase, potentially increasing convective heat transfer to the engine oil from engine 10, particularly from the cylinder head and the cylinder block. Generally, the faster the engine oil is heated, the faster the viscosity of the oil decreases, and the faster the friction losses are reduced. Further, the energy consumption of oil pump 208 may be reduced when bypass line 236 is open, which may reduce fuel consumption and improve the efficiency of engine 10. Accordingly, by programmatically controlling the diversion of oil through bypass line 236, it may be possible to adjust the fuel consumption and the emissions of engine 10.
While the embodiment shown in
In some previous examples, oil sump bypasses have been configured to divert oil directly downstream of the pump. However, the provision of bypass line 236 in the cylinder head may provide more heat to engine oil relative to a branch directly downstream of the pump, and may therefore heat the engine oil comparatively more quickly.
For example, after a cold start of engine 10, the cylinder head heats up comparatively quickly relative to the cylinder block due in part to the combustion processes. A portion of the engine oil heated in the cylinder head is recycled via bypass line 236 to the inlet of oil pump 208, bypassing oil sump 206. The heated engine oil may then be recirculated via supply line 212 to various consumers 214. Thus a quicker warm-up of engine 10 may be achieved relative to examples where oil is diverted upstream of the cylinder head and the cylinder block. Further, the comparatively fast heating of the engine oil during the warm-up phase of engine 10 may provide a correspondingly speedy decrease in engine oil viscosity, which may provide a reduction in friction losses at consumers 214. While
In some embodiments, bypass line 236 may include a bypass valve 244. Bypass valve 244 may be controlled remotely, such as via engine controller 12 as shown in the embodiment depicted in
Oil may be diverted to bypass line 236 according to an engine condition of engine 10. The engine conditions for which engine oil is diverted via bypass line 236, and at which bypass valve 244 is open, may be stored in instructions, which may include a condition map or lookup table, loaded into memory and executed by microprocessor 102 of engine controller 12. It will be appreciated that the engine conditions may include conditions such as speed, load, combustion, and temperature conditions of engine 10, as well as other conditions, such as warm-up, steady-state, and cool-down conditions. Non-limiting example engine conditions are described in more detail below.
In one scenario, the condition map may specify that, at some engine conditions, such as low engine speed, low load and/or low temperature conditions, bypass valve 244 is open. Low temperature conditions may include, but are not limited to, low engine temperature conditions such as engine oil temperature conditions below a first threshold and engine coolant temperature conditions below a second threshold. At other engine conditions, such as high engine speed, high load, and/or high temperature conditions (e.g., speeds, loads, and/or temperatures above respective thresholds), the condition map may indicate that bypass valve 244 is closed. High temperature conditions may include, but are not limited to, high engine temperature conditions such as high engine oil temperature conditions and high engine coolant temperature conditions.
In another scenario, the condition map may specify that during an engine warm-up condition, bypass valve 244 is open. At the end of the engine warm-up condition, the condition map may specify that bypass valve 244 is closed.
In yet another scenario, the condition map may specify that bypass valve 244 is controlled according to an engine oil temperature condition, such as a predetermined engine oil temperature threshold. Thus, the condition map may direct that bypass valve 244 is open below the predetermined engine oil temperature threshold and is closed when the engine oil temperature exceeds the predetermined engine oil temperature threshold.
In some embodiments, bypass line 236 may include a pressure control valve 240. For example, pressure control valve 240 may include a hydraulically controlled or actuated valve that opens if a predetermined oil pressure threshold is exceeded. In such embodiments, pressure control valve 240 operates in response to oil pressure in bypass line 236. Thus, in an embodiment including bypass valve 244, pressure control valve 240 may act automatically in response to oil pressure changes induced by contemporaneous actions at bypass valve 244. In one non-limiting example, pressure control valve 240 may include check valve, such as a 2/2 directional valve having two ports and two switching positions.
In embodiments that omit bypass valve 244, pressure control valve 240 controls the flow of oil through bypass line 236. In such embodiments, pressure control valve 240 may be electrically controlled by engine controller 12 or by other suitable hydraulic, pneumatic, mechanical, or magnetic controllers. In such embodiments, the condition map may include predefined engine oil pressure thresholds for opening pressure control valve 240 at different engine conditions, such that pressure control valve 240 opens or closes at different engine oil pressures under different engine conditions. Alternatively, in some examples, pressure control valve 240 may be controlled according to a predefined engine oil pressure threshold that is independent of the engine conditions.
Further, in some embodiments that omit bypass valve 244, pressure control valve 240, controlled by engine controller 12, may open at a predefined bypass set point (pthreshold,bypass) that is lower than a predefined overpressure set point (pthreshold,short) for opening an overpressure valve in a recycle loop, described in more detail below. In one scenario, pthreshold,bypass may be set at 2 bar and pthreshold,short may be set at 4 bar. However, it will be appreciated that any suitable set points may be employed within the scope of the present disclosure.
In some embodiments, bypass line 236 may also act as a recycle loop. In one example where bypass valve 244 is omitted, pressure control valve 240 may be configured or controlled to limit the oil pressure in the oil circuit, such that pressure control valve 240 opens automatically if a predefined oil pressure is exceeded. However, because bypass line 236 may be distant from the outlet of oil pump 208, it may be difficult to estimate head loss and pressure drop of those portions of the oil circuit that are intermediate to oil pump 208 and bypass line 236.
Thus, in some embodiments, oil delivery system 200 may include a recycle loop 248. Where provided, recycle loop 248 may adjust engine oil pressure within oil delivery system 200. For example, when bypass line 236 is closed, recycle loop 248 may divert a portion of the engine oil from the outlet of oil pump 208 to the inlet of oil pump 208. In one example, recycle loop 248 may branch from supply line 212 directly downstream of oil pump 208. Because this location is close to the outlet of oil pump 208, the effects of various pressure drops within oil delivery system 200 may be smaller than for a more distant location. For example, pressure drop across oil filter 216 may vary as a function of oil temperature. By locating the branch point for recycle loop 248 upstream of oil filter 216, such pressure drop variation may not affect the operation of recycle loop 248. Thus, it will be appreciated that, in some embodiments, oil filter 216, oil cooler 218, etc., may be located downstream in supply line 212 from an inlet of recycle loop 248.
In some embodiments, an overpressure valve 250 may be included within recycle loop 248. Overpressure valve 250 may open automatically if a predefined engine oil pressure threshold is exceeded. For example, overpressure valve 250 may automatically open at relatively high pressures, such as those that might be realized when bypass line 236 is closed after the warm-up phase has ended. In one scenario, of a predefined engine oil pressure threshold for opening overpressure valve 250 may be 4 bar. In some embodiments, overpressure valve 250 may be an automatically opening check valve such as a 2/2 directional valve with two feed lines or ports and two switching positions (e.g., open or closed).
It will be appreciated that extended storage at high temperatures may degrade engine oil lifetime. Thus, storing engine oil in an insulated reservoir may reduce the working life of engine oil. Accordingly, heated engine oil may be cooled in various components of oil delivery system 200. As described previously, the oil may be cooled in oil sump 206 by means of air cooling.
In some embodiments, oil sump 206 may include cooling fins, thereby increasing the surface area available for heat dissipation. The heat dissipation may occur via convective heat transfer to an air flow conducted past oil sump 206. In some examples, the air flow may be provided when the vehicle is in motion. Optionally, a fan may be included to supplement the air flow while the vehicle is in motion and/or to provide air flow when the vehicle is not in motion. Oil sump 206 may include materials selected in consideration of heat dissipation characteristics.
In some embodiments, oil cooler 218 may be included in supply line 212. For example, oil cooler 218 may be included downstream of oil pump 208 and upstream of the first consumer 214 in the oil circuit. In some embodiments, oil cooler 218 may comprise a liquid coolant oil cooler that extracts heat from the engine oil using the coolant of the cooling system 150. In some engine conditions, such as during a steady-state operating condition, coolant supplied to oil cooler 218 may reduce the temperature of the oil flowing through oil cooler 218, and may keep the engine oil temperature within a predetermined oil temperature range. In some other engine conditions, such as during cold start conditions, coolant heated by engine 10 may be supplied to oil cooler 218 to increase the temperature of the engine oil flowing through oil cooler 218.
In some embodiments, oil cooler 218 may be activated on demand. While the above-described oil cooler 218 relates to a liquid-cooled oil cooler, it will be appreciated that, in some embodiments, oil cooler 218 may comprise an air-operated oil cooler.
While the scenarios described below make reference to the bypass line operating parameters and hardware described above, it will be appreciated that method 300 may be used with other suitable bypass line operating parameters and/or hardware, and is not limited to the descriptions set forth.
With reference to
At 306, the routine selects one or more temperatures to utilize in determining whether to operate the oil bypass. For example, under some conditions, oil temperature may dictate whether to bypass oil, or not to bypass oil. In other conditions, coolant temperature may dictate whether to bypass oil, or not to bypass oil. Further, in still other example, a combination of various temperatures may determine whether to bypass oil or not around the sump.
In another example, the controller may utilize the speed of the engine or the load of the engine as an operating parameter to determine the oil delivery system operating state. In the present example, the controller holds instructions to execute an operating condition based on one or more of the engine coolant temperature ECT 310, or the temperature of the bypass line Tbypass 312, or the temperature of the main line Tmain 314, or the temperature of the sump Tsump 316, or the temperature of the exhaust Texhaust 318. There may be additional temperature sensors that the controller may utilize to determine the operating condition of the oil delivery system. When the ECT is less than the ambient temperature Tambient, or Tbypass is less than Tambient, or Tmain is less than Tambient or Tsump is less than Tambient or Texhaust is less than Tambient, the oil delivery system is set to first condition 320, which corresponds to opening the bypass valve, allowing a portion of the oil from the reciprocating engine components to be diverted around the oil sump to a lower pressure side of the oil pump while concurrently circulating oil from the reciprocating engine components via the oil sump to the lower pressure side of the oil pump. This may provide a faster heat up for the engine oil in a cold start scenario, potentially reducing engine frictional losses and/or emissions faster than if all of the engine oil were to be circulated through the oil sump.
When the ECT is not less than Tambient, or Tbypass is not less than Tambient, or Tmain is not less than Tambient or Tsump is not less than Tambient, or Texhaust is not less than Tambient, the oil delivery system is set to second condition 322, the bypass valve is closed and all the oil from the reciprocating engine components is routed to the lower pressure side of the oil pump via the oil sump.
It will be appreciated that the controller holds instructions for method 300, stored in memory and executed on a processor to perform the embodiment described above for method 300. It will also be appreciated that while method 300 illustrates a finite pathway for the controller to analyze the oil delivery system, other embodiments may comprise more than one loop of method 300 involving the controller to reevaluate a bypass line operating parameter 308 to determine the oil delivery system operating condition; a first condition 320 or a second condition 322. The reevaluation may incorporate different sensors or different combinations of sensors, such as engine speed sensors and/or load sensors with each evaluation, examples of which are discussed further below. In some embodiments, the controller may also comprise continual monitoring of the oil delivery system. Additionally or alternatively, method 300 may monitor the bypass line operating condition periodically and/or responsive to a trigger event. For example, in one scenario, method 300 may monitor the bypass line operating condition only on engine start.
In some embodiments, method 300 may include, heating the engine oil with heat from an engine coolant. For example, in a scenario where an engine coolant temperature exceeds an engine oil temperature, warmer engine coolant flowing through an oil cooler may transfer heat to the engine oil.
While method 300 is discussed above with respect to a cold start scenario, it will be appreciated that method 300 may used to operate the bypass line in any suitable situation.
For example, in one scenario, method 300 may operate the bypass line responsive to an engine speed parameter. Because low engine speeds may have lower engine operating temperatures, engine speed may be a proxy for engine temperature, such as when an engine is idling at a low speed. In such a scenario, method 300 may monitor engine speed and, upon detecting a low engine speed condition, open the control valve in the bypass line. Once the engine speed climbs above a preselected threshold speed, the bypass line may close. Thus, above the preselected threshold speed, all of the engine oil is circulated to the oil sump, so that only the oil sump supplies engine oil to the low pressure side of the oil pump.
For similar reasons, in another scenario, method 300 may operate the bypass line responsive to an engine load parameter Upon detecting a low engine load condition, method 300 may open the control valve in the bypass line so that oil is circulated to the low pressure side of the oil pump without passing through the oil sump. Once the engine load climbs above a preselected threshold load, the bypass line may close, so that all of the engine oil is circulated to the oil sump, and so that only the oil sump supplies engine oil to the low pressure side of the oil pump.
This concludes the description. The reading of it by those skilled in the art would bring to mind many alterations and modifications without departing from the spirit and the scope of the description. For example, I3, I4, I5, V6, V8, V10, and V12 engines operating in natural gas, gasoline, diesel, or alternative fuel configurations could use the present description to advantage.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2010-027816.5 | Apr 2010 | DE | national |
