Patent Application
20090139484
The present disclosure relates generally to an oil renewal system and, more particularly, to an automatically adjustable oil renewal system.
Engines require oil for lubrication of moving mechanical parts. Over time, the oil degrades and must be replaced. Typical oil replacement schedules require the oil to be changed every 500-1000 hrs of engine operation. Although effective at maintaining engine life, the interruption in engine operation required for the oil change can be a nuisance and cause a loss in production and profit, especially when the engine is powering a fleet vehicle at a commercial operation.
To minimize downtime, engine manufacturers have developed automatic oil renewal systems (ORS) that maintain good oil within the engine at all times. The ORS functions by metering used oil into the fuel system of the engine for subsequent combustion. Then, based on a detected low level of oil in the engine, new oil is automatically added to the system. Because each engine operates differently, the ORS must be tuned for a particular application to make sure that enough oil is being burned, while minimizing the amount of oil that is unnecessarily burned.
Although an improvement over periodic oil changes, the tuning described above can be difficult to perform properly. To tune the ORS, the oil must be manually sampled and tested for quality. If the quality is below an expected level, the ORS is adjusted to burn more oil. In contrast, if the oil quality is above the expected level, the burning of oil is turned down. The frequency of testing and adjusting is left to the discretion of the fleet operator/owner. And, unfortunately, this tuning process if often forgotten or disregarded resulting in poor engine operation and a reduction in engine life.
One attempt to minimize oil system tuning difficulty and required operator interaction is described in U.S. Pat. No. 5,964,318 (the '318 patent) issued to Boyle et al. on Oct. 12, 1999. Specifically, the '318 patent describes a system that measures the quality and level of lubricant in an engine lubricant reservoir. The system includes a valve for selectively directing a portion of the lubricant from the engine through a first conduit for return to the engine or through a second conduit for removal from the engine. Within the first conduit are one or more sensors for sensing the condition of the lubricant passing through the first conduit. These sensors are monitored by a controller, which is operative to selectively cause the valve to block the flow of lubricant through the first conduit and direct a portion of the lubricant through the second conduit based on the monitored conditions of the lubricant. The controller also directs a supply of fresh lubricant to the engine in response to the lubricant in the engine lubricant reservoir dropping below a predetermined level. The lubricant flowing through the second conduit may be intermittently mixed with fuel in the engine's fuel tank. The controller may limit the amount of lubricant that can be added to the fuel tank so as not to exceed a predetermined lubricant/fuel ratio for the engine.
Although the system of the '318 patent may limit tuning and operator interaction by automating some functions (i.e., by sensing a lubricant condition and removing oil from the engine based on the condition, and by automatically replenishing the system with new oil), it may be limited. That is, no oil may be removed from the engine of the '318 patent until the oil condition has deteriorated below an unacceptable quality level, and oil removal may only be periodic. Thus, the condition of the oil within the engine of the '318 patent may constantly vary between a good condition and an unacceptable condition. This lack of condition consistency may affect performance of the engine and make some operations, for example emissions generation, unpredictable. Further, the system of the '318 patent may be wasteful by replenishing oil based solely on a level of oil contained within the engine at any given time.
The disclosed oil renewal system is directed to overcoming one or more of the problems set forth above.
In one aspect, the present disclosure is directed to an oil renewal system for an engine. The oil renewal system may include a removal device configured to selectively remove oil from the engine, and a condition sensor situated to generate a condition signal indicative of an oil condition. The oil renewal system may also include a controller in communication with the condition sensor and the removal device. The controller may be configured to determine a deterioration rate of the oil based on the condition signal, and adjust a removal rate of the oil from the engine based on the deterioration rate.
In another aspect, the present disclosure is directed to a method of operating an engine. The method may include removing oil from the engine, and sensing a condition of oil circulated through the engine. The method may further include determining a deterioration rate of the oil based on the sensed condition, and adjusting a rate of the oil removing based on the deterioration rate.
An oil pan 18 may be connected to engine block 16 to form a cavity known as a crankcase 20 located below the combustion chambers. Lubricant, for example engine oil, may be provided from oil pan 18 to engine surfaces to minimize metal-on-metal contact and thereby inhibit damage to the surfaces. Oil pan 18 may serve as a sump for collecting and supplying this lubricant.
Fuel system 12 include components that cooperate to deliver injections of pressurized fuel into each of the combustion chambers. Specifically, fuel system 12 may include a tank 22 configured to hold a supply of fuel, and a fuel pumping arrangement 24 configured to pressurize the fuel and direct the pressurized fuel to a plurality of fuel injectors 26 by way of a manifold 28. A filtering element 30 may be located within a passageway 32 connecting pumping arrangement 24 to manifold 28. In one example, filtering element 30 may be located between filtering stages of pumping arrangement 24, if desired. Filtering element 30 may function to remove debris and/or water from the fuel pressurized by pumping arrangement 24.
Fuel pumping arrangement 24 may embody, for example, a high pressure source fluidly connected to tank 22 by way of a fuel line 34. Low pressure feed may be provide to the high pressure source, where the fuel may be pressurized up to as much as 300 MPa, in some cases. Fuel pressurized by pumping arrangement 24 and not injected by injectors 26 may be returned to tank 22 by way of a return line 36.
ORS 14 may have components that cooperate to maintain a target quantity and quality of oil within engine 10. In particular, ORS 14 may include, among other things, a pump 38 configured to draw oil from oil pan 18 and direct the oil either back into engine 10 or to mix with fuel of fuel system 12, one or more filtering element 40 configured to clean the oil, an oil removal device 41, an oil replenishment device 43, and a control system 42 configured to control operation of ORS 14.
Pump 38 may embody a linear or rotary actuator configured to draw oil from oil pan 18 via a passageway 44. It is contemplated that pump 38 may be dedicated to pressurizing only the oil of ORS 14 or, alternatively, may also serve as the primary oil pump of engine 10 tasked with circulating the oil throughout engine 10. Thus, pump 38 may be in fluid communication with fuel system 12 by way of a passageway 46, and, in one embodiment, also in fluid communication with engine block 16 by way of a passageway 48. One filtering element 40 may be located upstream of both passageways 46 and 48, while a second filtering element 40 may be located within passageway 46.
It is contemplated that filtering elements 40 may have different levels of filtration. That is, the filtering element 40 located upstream of passageways 46 and 48 may have a filtration size and/or efficiency less than that of the filtering element 40 located within passageway 46. The reason for the filtration differences may be associated with the maximum size and number of particles that can be tolerated by the lubrication circuits (not shown) of engine 10 and by fuel system 12. It is also contemplated that the filtering element 40 located within passageway 46 may be omitted, if desired, and filtering element 30 primarily relied on to sufficiently filter a mixture of oil and fuel.
Oil replacement device 41 and oil replenishment device 43 may both embody mechanisms operable to selective pass or inhibit the flow of oil. Specifically, oil replacement device 41 may be located downstream of pump 38, for example within passageway 46, to selectively regulate the flow of used oil into fuel system 12. Oil replacement device may embody an injector, a valve, a diverter, or any other known device regulated by control system 42 to remove precise quantities of oil from engine 10 at desired timings (discretely or continuously). Oil replenishment device 43 may likewise embody an injector, a valve, a diverter, or another known device located and regulated by control system 42 to selectively pass new oil to engine 10. In particular, oil replenishment device 43 may be located between engine 10 and an onboard supply 50 of new oil, for example between passageway 44 and onboard supply 50. In this manner, new oil from onboard supply 50 may be directed either directly into oil pan 18, or to a low pressure side of pump 38 for circulation first through engine 10 (i.e., when replacement device 41 is not passing oil into fuel system 12).
Control system 42 may be configured to regulate operation of ORS 14 in response to sensed oil conditions. For this purpose, control system 42 may include an oil quality sensor 52, an oil level sensor 54, and a controller 56 in communication with both of oil quality and oil level sensors 52, 54. Oil quality sensor 52 may be configured to sense a condition of the oil within engine 10, and to generate a condition signal indicative of this condition. The condition may be associated with a quality of the oil. For example, the condition could be an amount of soot entrained within the oil, a temperature of the oil, a viscosity of the oil, a total acid or base number of the oil, or another known condition. Although oil quality sensor 52 is shown as being located within passageway 48, it is contemplated that oil quality sensor 52 may be located anywhere within ORS 14, for example, within oil pan 18. Oil level sensor 54 may be configured to sense a parameter relating to an amount of oil contained within engine 10 and to generate a corresponding level signal. For example, the parameter could be associated with a level of the oil relative to a predefined position or angle in oil pan 18, a pressure of the oil at a predefined depth in oil pan 18, a temperature at a predefined location within oil pan 18, an electrical or acoustic dielectric constant or resistance of the oil within pan 18, or any other known parameter. As an instantaneous measured value for this parameter may not accurately depict the current amount of oil within engine 10, it is contemplated that the level signal provided by sensor 54 may be time averaged or otherwise processed and compensated, if desired. Although shown as being separate from oil quality sensor 52, it is contemplated that oil level sensor 54 may alternatively be integral with oil quality sensor 52, if desired.
Controller 56 may receive the quality and level signals from sensors 52 and 54, and regulate the operation of oil removal and replacement devices 41 and 43 in response thereto. Controller 56 may include all the components required to run an application such as, for example, a memory, a secondary storage device, and a processor, such as a central processing unit. One skilled in the art will appreciate that the controller 56 can contain additional or different components. Controller 56 may be dedicated to control of only ORS 14 or, alternatively, may readily embody a general engine microprocessor capable of controlling numerous engine functions. Associated with controller 56 may be various other known circuits such as, for example, power supply circuitry, signal conditioning circuitry, and solenoid driver circuitry, among others.
The disclosed oil renewal system may applicable to any engine where quality consistency of the engine's lubricating oil is important. The disclosed oil renewal system may ensure quality consistency by replacing deteriorated oil with new oil at a rate substantially equal to a rate of deterioration. The disclosed oil renewal system may provide the quality consistency in a cost efficient manner by replenishing the engine with new oil contingent upon an impending service. The operation of oil renewal system 14 will now be discussed.
During operation of engine 10, oil may be drawn from oil pan 18 and circulated throughout engine 10. The oil may be supplied to engine 10 by way of pump 38 and passageways 44 and 46. Alternatively, the oil may be supplied by a separate lubrication pump, if desired. As pump 38 circulates oil from pan 18 through engine 10, it may pass through filtering element 40, which may remove debris and/or water from the oil.
Even though the oil circulated through engine 10 may be continuously cleaned by filtering element 40, it may still degrade over time. For example, the oil may collect soot from surfaces of engine 10. As the soot entrained within the oil builds, it may agglomerate and block passageways within engine 10. As the passageways become restricted, less oil may pass to critical areas of engine 10. In addition, the lubricity and viscosity of the oil may change over time, thereby reducing the functionality of the oil. In order to ensure adequate protection of engine 10, the condition of the oil may be monitored and the oil may be selectively replaced in response to the condition.
The oil condition may be monitored by way of sensor 52 and adjusted by controller 56. That is, sensor 52 may periodically or continuously measure a parameter (e.g., soot loading, lubricity, viscosity, temperature, total acid number, total base number, etc.) of the oil as it passes through engine 10. Controller 56 may receive a quality signal from sensor 52 indicative of the oil condition. As controller 56 receives the quality signal over a period of time, controller 56 may determine a deterioration rate of the oil (i.e., a rate at which the condition monitored by sensor 52 changes). Controller 56 may then regulate operation of ORS 14 in response to this deterioration rate.
To regulate operation of ORS 14, controller 56 may selectively operate oil removal device 41 to release amounts of oil to fuel system 12. That is, oil removal device 41 may be controlled to pass oil from passageway 48 to fuel return line 36 by way of passageway 46 and filtering element 40. The amount of oil passed to fuel system 12 may correspond with the rate of oil deterioration determined by controller 56. Specifically, the amount of oil passed to fuel system 12 may be such that the oil retained within engine 10 (after replenishment of the removed oil by a substantially equal amount of clean oil) may maintain a substantially consistent quality level. Controller 56 may control oil removal device 41 to remove oil on a periodic or continuous basis.
As oil is removed to fuel system 12, the level of remaining within engine 10 may decrease. To ensure that engine 10 may always have an amount of oil sufficient to protect engine 10 (i.e., a target amount), controller 56 may selectively operate oil replenishment device 43 to allow new oil from onboard supply 50 to pass into engine 10. Oil replenishment device 43 may pass new oil into engine 10 such that the target amount of oil and quality of oil is maintained within engine 10 during normal operation. This target amount of oil and quality of oil may be different for different engines and for different applications of engine 10. This target amount and quality may each be more than minimum acceptable operating amounts and qualities, and selected for optimal operation of engine 10.
In order to minimize operating costs of engine 10, the amount of oil unnecessarily discarded from engine 10 should be minimized. That is, during some engine servicing events, the oil within engine 10 must be discarded either as part of the servicing or event or in order to facilitate the servicing event. Thus, new oil that is directed from onboard supply 50 into engine 10 just prior to the servicing event may be unnecessarily discarded, thereby increasing the operating cost of engine 10. To minimize this cost, controller 56 may change (i.e., reduce) the target amount of oil that should be maintained within engine 10 just prior to a pending servicing event. The indication of a pending servicing event may be received manually or automatically from a servicing system. Alternatively, the need for servicing may be determined and/or scheduled by controller 56 based on the condition of the oil or other machine or engine parameters. Then, based on a duration of time until the servicing event, controller 56 may gradually reduce the target amount of oil until the minimum acceptable amount of oil within engine 10 has been reached.
Several advantages may be associated with the disclosed oil renewal system. For example, the quality of oil maintained within engine 10 may be substantially consistent. A consistent oil quality may help ensure proper and predictable operation of engine 10. Further, the disclosed oil renewal system may minimize operating costs of engine 10, by minimizing the amount of oil unnecessarily discarded from engine 10 during a servicing event.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed oil renewal system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed oil renewal system. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
