A system and method for a variable displacement internal combustion engine using different types of pneumatic cylinder springs on skipped working cycles to control engine and aftertreatment system temperatures are described. The system and method may be used to rapidly heat up the aftertreatment system(s) and/or an engine block of the engine following a cold start by using one or more different types of pneumatic cylinder springs during skipped firing opportunities. By rapidly heating the aftertreatment system(s) and/or engine block, noxious emissions such as hydrocarbons, carbon monoxide, NO.sub.x and/or particulates, following cold starts are significantly reduced.

A system and method for a variable displacement internal combustion engine using different types of pneumatic cylinder springs on skipped working cycles to control engine and aftertreatment system temperatures are described. The system and method may be used to rapidly heat up the aftertreatment system(s) and/or an engine block of the engine following a cold start by using one or more different types of pneumatic cylinder springs during skipped firing opportunities. By rapidly heating the aftertreatment system(s) and/or engine block, noxious emissions such as hydrocarbons, carbon monoxide, NO.sub.x and/or particulates, following cold starts are significantly reduced.

The invention relates to a method of managing the oil temperature of a transmission of a motor vehicle, the transmission comprising a lubrication circuit and an oil cooling circuit, the oil temperature management circuit comprising a liquid/liquid heat exchanger mounted on the lubrication circuit, the lubrication circuit comprising a pump for circulating the oil in the lubrication circuit, and a temperature sensor wherein, before a starting stage of the vehicle, if the temperature of the oil is lower than a first value, the pump of the lubrication circuit is activated so as to circulate the oil in the liquid/liquid exchanger.

Aircraft engine oil tanks, lubrication systems, and associated methods are provided. The oil tank includes a first tank portion defining a first volume for holding oil and a second tank portion defining a second volume for holding oil, in fluid communication with the first volume. The first tank portion includes an oil outlet for delivering oil to a lubrication load via a pump. The first volume is in fluid communication with a vent opening for venting the oil tank. At least part of the second tank portion is disposed higher than the vent opening for retaining a quantity of oil inside the oil tank during a negative-g force flight condition and facilitate the recovery of the lubrication system following the negative-g force flight condition.

Methods and systems are provided for diagnosing degradation of a variable oil pump (VOP). In one example, a method may include during a deceleration fuel shut-off (DFSO) condition, diagnosing degradation of the VOP based on a rotational speed of the engine.

Methods and systems are provided for diagnosing degradation of a variable oil pump (VOP). In one example, a method may include during a deceleration fuel shut-off (DFSO) condition, diagnosing degradation of the VOP based on a rotational speed of the engine.

A method of controlling an electric oil pump (EOP) for a vehicle includes, if a current temperature of oil is lower than a reference temperature, determining whether an EOP RPM is lower than a minimum driving RPM, if the EOP RPM is lower than the minimum driving RPM, applying a first reduction rate for a first setting time and reducing a target line pressure and an instruction RPM of the EOP, if the EOP RPM is equal to or higher than the minimum driving RPM, determining whether vibration of the EOP RPM is generated above a reference vibration, and if the vibration is generated above the reference vibration, applying a second reduction rate for a second setting time and reducing the target line pressure or the instruction RPM of the EOP.

A method of controlling an electric oil pump (EOP) for a vehicle includes, if a current temperature of oil is lower than a reference temperature, determining whether an EOP RPM is lower than a minimum driving RPM, if the EOP RPM is lower than the minimum driving RPM, applying a first reduction rate for a first setting time and reducing a target line pressure and an instruction RPM of the EOP, if the EOP RPM is equal to or higher than the minimum driving RPM, determining whether vibration of the EOP RPM is generated above a reference vibration, and if the vibration is generated above the reference vibration, applying a second reduction rate for a second setting time and reducing the target line pressure or the instruction RPM of the EOP.

Embodiments of systems and methods disclosed provide a hydraulic fracturing unit that includes a reciprocating plunger pump configured to pump a fracturing fluid and a powertrain configured to power the reciprocating plunger pump. The powertrain includes a prime mover and a drivetrain, the prime mover including a gas turbine engine. The hydraulic fracturing unit also includes auxiliary equipment configured to support operation of the hydraulic fracturing unit including the reciprocating plunger pump and the powertrain. A power system is configured to power the auxiliary equipment. The power system includes a power source and a power network. The power source is configured to generate power for the auxiliary equipment. The power network is coupled to the power source and the auxiliary equipment, and configured to deliver the power generated by the power source to the auxiliary equipment. Associated systems including a plurality of hydraulic fracturing units are also provided.

A scavenge filter system according to an exemplary aspect of the present disclosure includes, among other things, a first scavenge pump stage positioned in a first flow path downstream of a first bearing compartment of a spool and a second scavenge pump stage positioned in a second flow path downstream of a second bearing compartment. The second bearing compartment houses a geared architecture mechanically coupled to the spool. A first scavenge filter fluidly couples the first scavenge pump stage to at least one oil reservoir. A second scavenge filter fluidly couples the second scavenge pump stage to the at least one oil reservoir. The first and second scavenge filters are separate and distinct. A method of filtering debris is also disclosed.