Abstract:
A method according to an exemplary aspect of the present disclosure includes, among other things, selectively powering a heating device to augment heating of an engine oil associated with an engine of a vehicle in a manner that influences an oil quality value of the engine oil.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to an oil maintenance strategy within a vehicle. The exemplary strategy includes actuating a heating device to augment heating of engine oil of the electrified vehicle in a manner that influences the quality of the engine oil. 
       BACKGROUND 
       [0002]    The need to reduce automotive fuel consumption and emissions is well known. Therefore, vehicles are being developed that reduce or completely eliminate reliance on internal combustion engines. Electrified vehicles are one type of vehicle currently being developed for this purpose. In general, electrified vehicles differ from conventional motor vehicles because they are selectively driven by one or more battery powered electric machines. Conventional motor vehicles, by contrast, rely exclusively on the internal combustion engine to drive the vehicle. 
         [0003]    Contaminants such as oil, gas and water must be periodically removed from the oil of an internal combustion engine to achieve efficient operation and for engine protection. Electrified vehicles equipped with internal combustion engines, such as hybrid vehicles, typically include a passive oil minder feature that forces the internal combustion engine into high power operation for a sufficient duration in order to help evaporate the contaminants Forced engine operation may be undesirable and time consuming. 
       SUMMARY 
       [0004]    A method according to an exemplary aspect of the present disclosure includes selectively powering a heating device to augment heating of an engine oil associated with an engine of a vehicle in a manner that influences an oil quality value of the engine oil. 
         [0005]    A further non-limiting embodiment of the foregoing method includes determining a measured oil quality value of the engine oil. 
         [0006]    A further non-limiting embodiment of either of the foregoing methods includes estimating the measured oil quality value based on at least one operating condition of the internal combustion engine. 
         [0007]    A further non-limiting embodiment of any of the foregoing methods includes estimating the measured oil quality value based on a number of cold starts of the internal combustion engine. 
         [0008]    A further non-limiting embodiment of any of the foregoing methods includes comparing the measured oil quality value to an oil quality target value. 
         [0009]    A further non-limiting embodiment of any of the foregoing methods includes continuing to actively monitor the measured oil quality value if the measured oil quality value exceeds the oil quality target value. 
         [0010]    A further non-limiting embodiment of any of the foregoing methods includes powering the heating device with a battery pack. 
         [0011]    A further non-limiting embodiment of any of the foregoing methods includes powering the heating device by running the engine at a power level that exceeds driver demanded power and then utilizing the excess power to power the heating device. 
         [0012]    A further non-limiting embodiment of any of the foregoing methods includes opening a valve to allow coolant that is heated by the heating device to be communicated to the engine in order to heat the engine oil. 
         [0013]    A further non-limiting embodiment of any of the foregoing methods includes closing the valve and turning the heating device OFF after a predefined amount of time. 
         [0014]    A method according to another exemplary aspect of the present disclosure includes warming an engine coolant with heat generated by a heating device of a conditioning system configured to condition an engine of an electrified vehicle, and warming engine oil with the engine coolant to a temperature sufficient to remove contaminants from the engine oil. 
         [0015]    A further non-limiting embodiment of the foregoing method includes opening a valve of the conditioning system to communicate the engine coolant heated by the heating device to the engine. 
         [0016]    A further non-limiting embodiment of either of the foregoing methods includes comparing a measured oil quality value to an oil quality target value prior to warming the engine coolant. 
         [0017]    A further non-limiting embodiment of any of the foregoing methods includes warming the engine coolant if the measured oil quality value is less than the oil quality target value. 
         [0018]    A further non-limiting embodiment of any of the foregoing methods includes turning the heating device OFF after a predefined amount of time if the measured oil quality value exceeds the oil quality target value. 
         [0019]    An electrified vehicle according to another exemplary aspect of the present disclosure includes a battery pack configured to selectively power a set of drive wheels, an engine configured to selectively power the drive wheels, a conditioning system configured to condition the engine and a control system configured to control the conditioning system to influence an oil quality value of oil of the engine. 
         [0020]    A further non-limiting embodiment of the foregoing electrified vehicle includes a heating device configured to heat an engine coolant that is used to heat the oil. 
         [0021]    A further non-limiting embodiment of either of the foregoing electrified vehicles includes the heating device configured as a positive temperature coefficient (PTC) heater. 
         [0022]    A further non-limiting embodiment of any of the foregoing electrified vehicles includes the control system configured to open a valve and actuate a heating device to influence the oil quality value of the oil. 
         [0023]    A further non-limiting embodiment of any of the foregoing electrified vehicles includes a primary coolant loop and a secondary coolant loop. 
         [0024]    The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
         [0025]    The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  schematically illustrates a powertrain of an electrified vehicle. 
           [0027]      FIG. 2  illustrates a vehicle system of an electrified vehicle. 
           [0028]      FIG. 3  schematically illustrates a control strategy for influencing the quality of engine oil used by an engine of an electrified vehicle. 
           [0029]      FIG. 4  is a graphical representation of an engine oil quality measurement. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    This disclosure details an exemplary oil maintenance strategy for controlling a vehicle equipped with an engine. A heating device may be selectively powered to influence the oil quality of engine oil. Once actuated, the heating device generates heat for warming an engine coolant that is passed through the engine. The engine coolant gives off heat to the engine oil through the engine structure to warm the engine oil. Warming the engine oil in this manner allows contaminants to be cleaned (e.g., boiled) out of the oil, thereby improving an oil quality value of the engine oil. The use of the auxiliary heating device can shorten the duration of the oil maintenance strategy, allowing the vehicle to return to a normal mode of operation sooner. These and other features are discussed in greater detail in the following paragraphs of this detailed description. 
         [0031]      FIG. 1  schematically illustrates a powertrain  10  for an electrified vehicle  12 . In one non-limiting embodiment, the electrified vehicle  12  is a plug-in hybrid electric vehicle (PHEV). However, other electrified vehicles could also benefit from the teachings of this disclosure, including but not limited to, battery electric vehicles (BEV&#39;s) and hybrid electric vehicles (HEV&#39;s). The teachings of this disclosure are further applicable to conventional motor vehicles. 
         [0032]    In one non-limiting embodiment, the powertrain  10  is a power-split powertrain system that employs a first drive system and a second drive system. The first drive system may include a combination of an engine  14  and a generator  18  (i.e., a first electric machine). The second drive system includes at least a motor  22  (i.e., a second electric machine) and a battery pack  24 . In this example, the second drive system is considered an electric drive system of the powertrain  10 . The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels  28  of the electrified vehicle  12 . Although a power-split configuration is shown, this disclosure extends to any hybrid or electric vehicle including full hybrids, parallel hybrids, series hybrids, mild hybrids or micro hybrids. 
         [0033]    The engine  14 , which in one embodiment is an internal combustion engine, and the generator  18  may be connected through a power transfer unit  30 , such as a planetary gear set. Of course, other types of power transfer units, including other gear sets and transmissions, may be used to connect the engine  14  to the generator  18 . In one non-limiting embodiment, the power transfer unit  30  is a planetary gear set that includes a ring gear  32 , a sun gear  34 , and a carrier assembly  36 . 
         [0034]    The generator  18  can be driven by the engine  14  through the power transfer unit  30  to convert kinetic energy to electrical energy. The generator  18  can alternatively function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft  38  connected to the power transfer unit  30 . Because the generator  18  is operatively connected to the engine  14 , the speed of the engine  14  can be controlled by the generator  18 . 
         [0035]    The ring gear  32  of the power transfer unit  30  may be connected to a shaft  40 , which is connected to vehicle drive wheels  28  through a second power transfer unit  44 . The second power transfer unit  44  may include a gear set having a plurality of gears  46 . Other power transfer units may also be suitable. The gears  46  transfer torque from the engine  14  to a differential  48  to ultimately provide traction to the vehicle drive wheels  28 . The differential  48  may include a plurality of gears that enable the transfer of torque to the vehicle drive wheels  28 . In one embodiment, the second power transfer unit  44  is mechanically coupled to an axle  50  through the differential  48  to distribute torque to the vehicle drive wheels  28 . In one embodiment, the power transfer units  30 ,  44  are part of a transaxle  20  of the electrified vehicle  12 . 
         [0036]    The motor  22  can also be employed to drive the vehicle drive wheels  28  by outputting torque to a shaft  52  that is also connected to the second power transfer unit  44 . In one embodiment, the motor  22  is part of a regenerative braking system. For example, the motor  22  can each output electrical power to the battery pack  24 . 
         [0037]    The battery pack  24  is an exemplary electrified vehicle battery. The battery pack  24  may be a high voltage traction battery pack that includes a plurality of battery assemblies  25  (i.e., battery arrays or groupings of battery cells) capable of outputting electrical power to operate the motor  22 , the generator  18  and/or other electrical loads of the electrified vehicle  12 . Other types of energy storage devices and/or output devices can also be used to electrically power the electrified vehicle  12 . 
         [0038]    In one non-limiting embodiment, the electrified vehicle  12  has two basic operating modes. The electrified vehicle  12  may operate in an Electric Vehicle (EV) mode where the motor  22  is used (generally without assistance from the engine  14 ) for vehicle propulsion, thereby depleting the battery pack  24  state of charge up to its maximum allowable discharging rate under certain driving patterns/cycles. The EV mode is an example of a charge depleting mode of operation for the electrified vehicle  12 . During EV mode, the state of charge of the battery pack  24  may increase in some circumstances, for example due to a period of regenerative braking. The engine  14  is generally OFF under a default EV mode but could be operated as necessary based on a vehicle system state or as permitted by the operator. 
         [0039]    The electrified vehicle  12  may additionally operate in a Hybrid (HEV) mode in which the engine  14  and the motor  22  are both used for vehicle propulsion. The HEV mode is an example of a charge sustaining mode of operation for the electrified vehicle  12 . During the HEV mode, the electrified vehicle  12  may reduce the motor  22  propulsion usage in order to maintain the state of charge of the battery pack  24  at a constant or approximately constant level by increasing the engine  14  propulsion. The electrified vehicle  12  may be operated in other operating modes in addition to the EV and HEV modes within the scope of this disclosure. 
         [0040]    The electrified vehicle  12  may also include a charging system  16  for charging the energy storage devices (e.g., battery cells) of the battery pack  24 . The charging system  16  may be connected to an external power source (e.g., electrical grid, not shown) for receiving and distributing power throughout the vehicle. The charging system  16  may also be equipped with power electronics used to convert AC power received from the external power supply to DC power for charging the energy storage devices of the battery pack  24 . The charging system  16  may also accommodate one or more conventional voltage sources from the external power supply (e.g., 110 volt, 220 volt, etc.). 
         [0041]    The powertrain  10  shown in  FIG. 1  is highly schematic and is not intended to limit this disclosure. Various additional components could alternatively or additionally be employed by the powertrain  10  within the scope of this disclosure. 
         [0042]      FIG. 2  is a highly schematic depiction of a vehicle system  56  that may be employed by an electrified vehicle, such as the electrified vehicle  12  of  FIG. 1 . The various components of the vehicle system  56  are shown schematically to better illustrate the features of this disclosure. These components, however, are not necessarily depicted in the exact locations where they would be found in an actual vehicle and are not necessarily shown to scale. 
         [0043]    The vehicle system  56  is adapted to schedule and effectuate conditioning (e.g., warming) of oil  58  of the engine  14  in a manner that influences an oil quality value of the oil  58 . The oil quality value is a calibrated expression of the amount of contaminants, such as fuel and water, present in the oil  58 . In one non-limiting embodiment, the oil  58  is heated to a desired temperature to clean the oil  58  of the contaminants. Conditioning the oil  58  during certain vehicle conditions may improve the fuel efficiency, durability, customer satisfaction and electric range of the electrified vehicle  12 , among providing other potential benefits. 
         [0044]    In one non-limiting embodiment, the exemplary vehicle system  56  includes the engine  14 , a conditioning system  60 , a high voltage battery pack  24 , a charging system  16  and a control module  76 . The engine  14  may be an internal combustion engine or any other type of engine. The engine  14  houses and circulates the oil  58 , which has an optimal operating temperature range, to lubricate the various components of the engine  14 . 
         [0045]    The conditioning system  60  is configured to thermally manage the engine  14 . In one non-limiting embodiment, the conditioning system  60  includes a primary coolant loop  62  and a secondary coolant loop  64 . The primary coolant loop  62  and the secondary coolant loop  64  each circulate a coolant C, such as with a pump (not shown). Although not shown, the conditioning system  60  may additionally include one or more heat exchangers for conditioning the coolant C within the primary coolant loop  62  and/or the secondary coolant loop  64 . The secondary coolant loop  64  may be configured to both augment conditioning of the engine  14  and to condition the interior cabin of the electrified vehicle  12 . During some conditions, excess heat is transferred from the engine  14  to the coolant C within the primary coolant loop  62 . During other conditions, the secondary coolant loop  64  is fluidly connected to the primary coolant loop  62  to warm the oil  58  of the engine  14  by transferring heat from the coolant C into the oil  58 , as further discussed below. 
         [0046]    A valve  66  controls the flow of coolant C between the secondary coolant loop  64  and the primary coolant loop  62 . For example, when the valve  66  is closed, the secondary coolant loop  64  is fluidly isolated or separated from the primary coolant loop  62 . The valve  66  may be selectively opened to fluidly connect or combine the secondary coolant loop  64  and the primary coolant loop  62 . 
         [0047]    A heating device  68  may be positioned within the secondary coolant loop  64 . The heating device  68  is configured to selectively condition the coolant C within the secondary coolant loop  64 , such as by warming it. In one non-limiting embodiment, the heating device  68  is a positive temperature coefficient (PTC) heater positioned in direct contact with the coolant C. In another non-limiting embodiment, the heating device  68  is an electrically powered heating device. Other heating devices are also contemplated within the scope of this disclosure. 
         [0048]    In one non-limiting embodiment, the heating device  68  is powered by grid power when the vehicle is “on-plug” (i.e., plugged into an external power source  70  when the vehicle is OFF). In another non-limiting embodiment, the heating device  68  is powered by the battery pack  24  when the vehicle is “off-plug” (i.e., unplugged from the external power source  70 ) or during operation of the electrified vehicle  12 . In yet another non-limiting embodiment, the heating device  68  is powered by a self-contained energy storage device, such as a separate battery or special reserve power supply. In yet another non-limiting embodiment, the heating device  68  is powered by operating the engine  14  above driver demanded power and utilizing the excess power to power the heating device  68  rather than sending the excess power to the battery pack  24 . 
         [0049]    The battery pack  24  may include one or more battery assemblies having a plurality of battery cells or other energy storage devices. The energy storage devices of the battery pack  24  store electrical energy that is selectively supplied to power various electrical loads residing on-board the electrified vehicle  12 . These electrical loads may include various high voltage loads (e.g., electric machines, etc.) or various low voltage loads (e.g., lighting systems, low voltage batteries, logic circuitry, etc.). 
         [0050]    The charging system  16  may include a charging port  72  located on the electrified vehicle  12  and a cordset  74  that is operably connectable between the charging port  72  and the external power source  70 . The charging port  72  is adapted to selectively receive energy from the external power source  70 , via the cordset  74 , and then supply the energy to the battery pack  24  for charging the battery cells. If necessary, the charging system  16  may convert alternating current received from the external power source  70  to direct current DC for charging the high voltage battery pack  24 . The charging system  16  is also configured to establish maximum available charging currents for charging the battery pack  24 , among other operational parameters. The external power source  70  includes off-board power, such as utility/grid power, in one non-limiting embodiment. 
         [0051]    The control module  76  may be part of an overall vehicle control unit, such as a vehicle system controller (VSC), or could alternatively be a stand-alone control unit separate from the VSC. In one non-limiting embodiment, the control module  76  is part of an engine control module (ECM) of the electrified vehicle  12 . The control module  76  includes executable instructions for interfacing with and commanding operation of the various components of the vehicle system  56  including, but not limited to, the engine  14 , the battery pack  24 , the charging system  16 , the valve  66  and the heating device  68 . The control module  76  may include multiple inputs and outputs for interfacing with the various components of the vehicle system  56 . The control module  76  may additionally include a processing unit and one or more types of memory for executing the various control strategies and modes of the vehicle system  56 . 
         [0052]    In one non-limiting embodiment, the control module  76  is configured to selectively open the valve  66  and actuate the heating device  68  to augment warming the oil  58  of the engine  14 . Once the valve  66  is opened, heated coolant C from the secondary coolant loop  64  mixes with the coolant C of the primary coolant loop  62 . The heating device  68  adds additional heat to the coolant C that can then be used to warm the oil  58  to a temperature sufficient to clean the oil  58  of contaminants, thereby speeding up oil warm-up times. In another non-limiting embodiment, the control module  76  is configured to determine when to start and stop conditioning the engine  14  using the heating device  68 . In yet another non-limiting embodiment, the control module  76  is configured to determine when the start and stop charging the battery pack  24  and determine the charging rate that should be used. These are but several non-limiting examples of the many functions of the control module  76  of the vehicle system  56 . 
         [0053]      FIG. 3 , with continued reference to  FIGS. 1-2 , schematically illustrates a control strategy  100  for actively influencing the oil quality of the oil  58  used by the engine  14  of the electrified vehicle  12 . The oil quality is “influenced” in by removing contaminants from the oil  58  after the oil quality has fallen below a threshold value. The exemplary control strategy  100  may include actively monitoring an oil quality value associated with the oil  58  and then adjusting operation of the conditioning system  60  based on the monitored oil quality value. Of course, the electrified vehicle  12  is capable of implementing and executing other control strategies within the scope of this disclosure. In one non-limiting embodiment, the control module  76  is programmed with one or more algorithms adapted to execute the control strategy  100 , or any other control strategy. The control strategy  100  may be stored as executable instructions in the non-transitory memory of the control module  76 , in one non-limiting embodiment. 
         [0054]    As shown in  FIG. 3 , the control strategy  100  begins at block  102 . At block  104 , the control module  76  may estimate and/or measure various operating conditions of the electrified vehicle  12 . For example, the control module  76  may receive sensory feedback from one or more sensors associated with the vehicle system  56 . Exemplary operating conditions include, but are not limited to, engine  14  temperature, battery pack  24  state of charge (SOC), ambient conditions, etc. 
         [0055]    Next, at block  106 , the control strategy  100  may determine an oil quality target value Q target . The oil quality target value Q target  represents the threshold against which a measured oil quality value Q meas  is compared to determine whether the oil quality of the oil  58  of the engine  14  has deteriorated to such a level that corrective action is required. In one non-limiting embodiment, the oil quality target value Q target  is a quantitative value that can be expressed generically as an integer between the numbers  1  and  10 . The oil quality target value Q target  may be set at any value and is a design specific parameter of the control strategy  100 . In one non-limiting embodiment, the oil quality target value Q target  is stored in the memory of the control module  76 , such as within a look-up table. In another embodiment, the oil quality target value Q target  is a variable value that could change based on ambient temperatures, vehicle speed, etc. 
         [0056]    Next, at block  108 , the measured oil quality value Q meas  associated with the oil  58  used by the engine  14  may be measured or inferred. The measured oil quality value Q meas  can be expressed generically as an integer between 0 and 10 and represents an estimate of the amount of contaminants within the engine oil, with ‘0’ representing relatively poor oil quality and ‘10’ representing relatively good oil quality, for example. The measured oil quality value Q meas  may be estimated based on one or more operating conditions of the electrified vehicle  12 . In one non-limiting embodiment, the operating conditions include the number of cold starts of the engine  14  (i.e., the number of times the engine  14  is forced into operation). The measured oil quality value Q meas  could be estimated based on a single engine parameter or a combination of engine parameters within the scope of this disclosure. 
         [0057]    An exemplary plot  80  of the measured oil quality value Q meas  is shown in  FIG. 4 . As illustrated, the measured oil quality value Q meas  (shown on the X-axis) may be a function of the number of engine cold starts (shown on the Y-axis). As also indicated by the plot  80 , the measured oil quality value Q meas  decreases as the number of cold starts increases. In other words, the measured oil quality value Q meas  is inversely related to the number of engine cold starts. 
         [0058]    Referring again to  FIG. 3 , the measured oil quality value Q meas  is next compared against the oil quality target value Q target  at block  110 . If the measured oil quality value Q meas  exceeds the oil quality target value Q target , the control strategy  100  returns to block  108  and actively continues to monitor the measured oil quality value Q meas . 
         [0059]    If, however, the measured oil quality value Q meas  is determined to be less than the oil quality target value Q target  at block  110 , indicating that the oil quality has dropped below a desired threshold of quality, the control strategy  100  may proceed to block  112  by opening the valve  66 , thereby fluidly connecting the primary and secondary coolant loops  62 ,  64  of the conditioning system  60 . The heating device  68  is powered ON at block  114  to augment warming of the oil  58  of the engine  14 . For example, actuating the heating device  68  warms the coolant C in the secondary coolant loop  64 , which has already been fluidly connected to the primary coolant loop  62  by virtue of opening the valve  66 . The warmed coolant C may therefore be communicated through the engine  14  for adding additional heat to the oil  58 . The oil  58  is heated to a temperature sufficient to clean the oil  58  of contaminants. In one non-limiting embodiment, the contaminants are boiled out of the oil  58  due to the additional heat that is added to the coolant C by the heating device  68 . 
         [0060]    In one non-limiting embodiment, the heating device  68  is powered by the battery pack  24 , such as during a drive cycle of the electrified vehicle  12 . In another non-limiting embodiment, the heating device  68  is powered by the external power source  70 , such as during on-plug conditions in which the corset  74  is connected to both the charging port  72  and the external power source  70 . In this way, the oil  58  can be cleaned of contaminants whether or not the electrified vehicle  12  is currently in operation. 
         [0061]    After a predefined amount of time, which may be programmed in the control module  76  or stored in another look-up table, the measured oil quality value Q meas  is again compared against the oil quality target value Q target  at block  116 . The control strategy  100  continues to warm the oil  58  by heating the coolant C with the heating device  68  at block  118  if the measured oil quality value Q meas  remains less than the oil quality target value Q target . Alternatively, if the measured oil quality value Q meas  is determined to exceed the oil quality target value Q target  after the predefined amount of time, the valve  66  is closed and the heating device  68  is actuated OFF at block  120 . The control strategy  100  may then end at block  122 . 
         [0062]    Although the different non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
         [0063]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure. 
         [0064]    The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.