Abstract: A cooling apparatus 1A includes an engine 50A having a cylinder head 52A having a head side W/J 521A equipped with partial W/J 521aA through 521dA individually incorporated into four different cooling systems, first recess/projection portions P capable of generating a flow separation of cooling water in accordance with a change of the flow rate within a range of a maximum flow rate of the cooling water being provided to the head side W/J 521A, and control means for executing a control of changing the flow rate of the cooling water that flows through the first cooling medium passageway in accordance with operating conditions of the engine including a case where the control means partially changes in each of the plurality of the partial cooling medium passageways.

Abstract: A combustion management system for a combustion engine having at least one cylinder with an intake means comprising a sliding port valve and an intake solenoid poppet valve arranged in series and provided at a distance from the cylinder ends, and an exhaust solenoid poppet valve provided at each of the cylinder ends, the system comprising: a valve control means for controlling the intake solenoid poppet valve and the exhaust solenoid poppet valve independently of the position of the piston moving within the cylinder to control the compression and expansion ratios, wherein the piston moves over and past the intake means during each stroke.

Abstract: Disclosed is a device for cooling an internal combustion engine in which circulation of cooling water is halted until the cooling water reaches a predetermined temperature, wherein decline in the durability of a radiator, which is caused by thermal strain that occurs when circulation of the cooling water is restarted and the cooling water is introduced into the radiator, is suppressed. An internal combustion engine (10) comprises an electric pump (23), a water temperature sensor (92), a radiator (21), and a thermostat (22). The water temperature sensor (92) detects a cooling water temperature (THW). The radiator (21) is capable of circulating the cooling water between the radiator (21) and an engine cooling system (13). If the cooling water temperature (THW) is equal to or greater than a valve opening temperature (TZ), the thermostat (22) opens and the cooling water is introduced into the radiator (21).

Abstract: A cooling apparatus that cools with coolant a subject of cooling, which is a heat source. The cooling apparatus includes a cooling circuit, an electric pump, a switching section, and a control section. Through circulation of the coolant, air in the cooing circuit is caused to flow to an air bleeding portion and is discharged from the cooling circuit through the air bleeding portion. The switching section is capable of switching the operation mode of the electric pump between a normal mode and an air bleeding mode for collecting air in the cooling circuit to the air bleeding portion. During the air bleeding mode, the control section is capable of controlling the electric pump to change a coolant displacement from the electric pump according to a change pattern that allows stagnant air in sections of the cooling circuit to flow to the air bleeding portion.

Abstract: The cooling device is provided with an engine including a cylinder block, a cylinder head, and a W/J which is a single system as a whole and which causes coolant to flow from the cylinder block to the cylinder head. The W/J branches into first and second inner paths within the cylinder block, and joints together within the cylinder head. The first inner path is provided with an opening and closing valve for permitting and prohibiting the flow of the coolant based on the pressure of the coolant.

Abstract: A cooling device for engine includes: an engine having a cylinder block, a cylinder head and a gasket, the gasket being provided between the cylinder block and the cylinder head and having a high thermal conductivity member allowing heat transfer between an upper part of a cylinder and the cylinder head with a heat transfer rate higher than the other part, a partial W/J being provided around the high thermal conductivity member; and an ECU performing a control for changing flow condition of cooling medium flowing in the partial W/J, according to combustion engine operation condition.

Abstract: A cooling apparatus includes an engine equipped with a cylinder block and a cylinder head, a flow rate control valve capable of suppressing a cooling capacity of the cylinder head without suppressing a cooling capacity of the cylinder block, and control means that performs a control to suppress the cooling capacity of the cylinder head by controlling the flow rate control valve. The flow rate control valve is cooling capacity control means that controls the cooling capacity of the cylinder head by controlling the flow rate of cooling water that flows through a head side W/J formed in the cylinder head.

Abstract: An internal combustion engine includes a cooling fluid circuit and a pumping circuit. The pumping circuit drives an ejector pump located along the cooling fluid circuit, enabling a reduced parasitic load on the engine from pumping cooling fluid through the cooling fluid circuit.

Abstract: Actuating device for a recirculation pump of a cooling circuit of an internal combustion engine comprising a pulley suitable for being rotationally driven by the engine, a driven shaft for driving the pump and an electromagnetically controlled coupling interposed between the pulley and the driven shaft, in which the electromagnetic coupling comprises an electromagnet, coupling mechanism controlled by the electromagnet and mobile between an engagement position in which the pulley is connected to the driven shaft and a disengagement position, and an elastic member for maintaining an engagement member in the engaged position when the electromagnet is not energized.

Abstract: The present invention relates to a system for cooling a rotary engine, the system comprising a drive shaft having a bore hole and at least one of a coolant transmission hole in fluid communication with the bore hole. At least one of a coolant distribution channel is in fluid communication with the coolant transmission hole. A coolant fluid channel receives a coolant liquid from the coolant distribution channel, wherein the coolant liquid is circulated between the bore hole and the outer coolant fluid channel to cool the rotary engine. Other exemplary embodiments include a centripetal force pump formed by at least the rotation of the drive shaft, which circulates the coolant liquid between the drive shaft bore hole and the outer coolant fluid channel to cool the rotary engine, and adjusting the coolant liquid flow rate based, in part, on the RPM of the drive shaft.

Abstract: A cooling system for variable cylinder engines is is designed to most efficiently cool engine during engine full displacement operation and to heat inactive cylinders and cool active cylinders during engine reduced displacement operation. By heating inactive cylinders, the fuel efficiency during reactivation is improved and the optimal operation of the catalytic converter may be maintained.

Abstract: A hybrid ECU executes a program including the steps of: setting a fan driving level F for a cooling fan, as based on a high voltage battery's temperature TB, SOC and input and output currents, and a vehicular cabin's internal temperature and background noise; detecting from a signal transmitted from a voltage sensor the voltage of an auxiliary battery serving as a power supply for the cooling fan; and setting a duty command value for the cooling fan from fan driving level F and the auxiliary battery's voltage so that the duty command value is smaller as a voltage of the auxiliary battery is higher.

Abstract: In a two-cycle, opposed-piston internal combustion engine, opposed pistons disposed in a cylinder are coupled to a pair of side-mounted crankshafts by connecting rods that are subject to substantially tensile forces acting between the pistons and the crankshafts. This geometry reduces or eliminates side forces between the pistons and the bore of the cylinder. The cylinder and the pistons are independently cooled to reduce cylindrical deformation caused by thermal expansion during engine operation.

Abstract: The ECU includes: a stop control portion controlling an electric water pump to stop, when an engine provided with the electric water pump pressure-feeding a coolant is warmed up; a first drive control portion controlling the electric water pump to drive for a predetermined period at least before the stop control portion performs a control, when a coolant temperature thw in starting the engine is equal to or higher than a predetermined value ?. The electric water pump corresponds to a variable water pump capable of changing the flow rate of the coolant.

Abstract: A cooling system for internal combustion engines provides directed flows of heated or cooled coolant to various engine components and/or accessories as needed. By providing directed flows, the overall coolant flow volume is reduced from that of conventional cooling systems, allowing for a smaller capacity water pump to be employed which results in a net energy savings for the engine. Further, by reducing the overall coolant flow volume, the hoses and/or galleries required for the directed flows are reduced from those of conventional cooling systems, providing a cost savings and a weight savings. Finally, by preferably employing an impellor type water pump, the expense of an electric water pump and its associated control circuitry can be avoided. The direct flows are established by a multifunction valve which, in a preferred implementation, comprises a two-plate valve wherein each plate is operated by a wax motor.

Abstract: A cooling system is provided for a combustion engine having at least one pressure sensor and a diaphragm. The diaphragm is impermeable to a coolant of the cooling system and in contact with the coolant on a first side. A sensor device of the at least one pressure sensor is arranged separated from the coolant on a second side of the diaphragm located opposite the first side and configured to determine a pressure of the coolant.

Abstract: A hybrid cooling system for an engine is provided. The system comprises a block oil cooling circuit, a head coolant cooling circuit, the head and block circuits having a common heat exchanger. The system also includes a flow device in the head cooling circuit for preventing coolant flow in the head cooling circuit at least during a first phase of a warm-up phase of the internal combustion engine, a delivery device in the block cooling circuit which delivers engine oil constantly under pressure through the block cooling circuit to bearing points in a cylinder block and to bearing points in a cylinder head, and a control element arranged in a control line to reduce the delivery capacity of the delivery device through the block cooling circuit at least during the first phase of the warm-up phase. In this way, heat transfer in the common heat exchanger may be substantially prevented.

Abstract: A cooling system for an engine is provided. In one embodiment, an internal combustion engine comprises a cabin heat exchanger circuit including a connecting line opening on an inlet side into a cylinder block coolant jacket, a main coolant pump arranged in the cabin heat exchanger circuit, an auxiliary coolant pump arranged in the connecting line, and a check valve. In this way, additional cooling and/or heating may be provided to the engine and associated components by the auxiliary coolant pump.

Abstract: Actuating device for a recirculation pump of a cooling circuit of an internal combustion engine comprising a pulley suitable for being rotationally driven by the engine, a driven shaft for driving the pump and an electromagnetically controlled coupling interposed between the pulley and the driven shaft, in which the electromagnetic coupling comprises an electromagnet, coupling mechanism controlled by the electromagnet and mobile between an engagement position in which the pulley is connected to the driven shaft and a disengagement position, and an elastic member for maintaining an engagement member in the engaged position when the electromagnet is not energized.

Abstract: The present disclosure is directed to various embodiments of systems and methods for cooling a combustion chamber of an engine. One method includes introducing fuel into the combustion chamber of an engine having an energy transfer device that moves through an intake stroke, a compression stroke, a power stroke, and an exhaust stroke. The method further includes monitoring a temperature of the combustion chamber. When the temperature reaches a predetermined value, the method also includes introducing coolant into the combustion chamber only during at least one of the power stroke and the exhaust stroke of the energy transfer device.

Abstract: A method for operating an engine system comprises charging a cylinder of the engine system with exhaust from upstream of an exhaust turbine at a first rate. The method further comprises charging the cylinder with exhaust from downstream of the turbine at a second rate. The exhaust from downstream of the turbine is routed to the cylinder via a low-pressure exhaust-gas recirculation path. The method further comprises increasing the second rate relative to the first rate in response to a coolant-overheating condition.

Abstract: A drive component for driving an electric water pump for causing engine coolant to flow is mounted in an engine compartment. When the ignition is off and the temperature of a exhaust heat recovery device is above a temperature, an ECU estimates a peak temperature in the engine compartment after the stop of the engine. When the peak temperature is above a temperature, the ECU stops the engine and drives the electric water pump and an electric fan for cooling the drive component for driving the electric water pump.

Abstract: A coolant circulation circuit for an engine includes a first coolant line through which coolant heated in an engine and circulated in a radiator passes, a second coolant line through which coolant heated in the engine and circulated in additional elements passes, a bypass coolant line through which coolant heated in the engine passes, a coolant outlet where the coolant flows into the engine, a first chamber where the coolant having passed through the bypass coolant line flows in, a second chamber where the coolant having passed through the second coolant line flows in, a partition formed between the first chamber and the second chamber and a thermostat selectively blocking the first chamber from the second chamber.

Abstract: An object of the present invention is to ensure appropriate cooling amounts for two exhaust ports, respectively, in an internal combustion engine in which an exhaust port that communicates with an inlet of a turbine of a turbocharger and an exhaust port that does not communicate with the inlet of the turbine are formed in a cylinder head. A cooling apparatus for an internal combustion engine of the present invention has a first exhaust port and a second exhaust port formed in a cylinder head of the internal combustion engine. The first exhaust port communicates with an inlet of a turbine of the turbocharger. The second exhaust port does not communicate with the inlet of the turbine. Each cylinder of the internal combustion engine includes a first exhaust valve that communicates with the first exhaust port and a second exhaust valve that communicates with the second exhaust port.

Abstract: An internal combustion engine has a cylinder-head-passage through which an engine coolant flows toward a water jacket when a water pump is operated. The water pump is an electric water pump utilizing the electric power charged in the battery. A radiator is provided in the cylinder-head-passage. Even after the engine is shut off, the water pump is kept driven.

Abstract: An arrangement for controlling cooling of a gaseous medium for a supercharged combustion engine (2): A low temperature cooling system with a coolant, a coolant pump (27) for circulating the coolant in the cooling system. A cooler (10, 15) in which a gaseous medium which contains water vapour is intended to be cooled by the coolant in the cooling system. At least one sensor (33, 35) for detecting a parameter which indicates whether the gaseous medium is cooled so much that there is ice formation or risk of ice formation in the cooler (10, 15). A control unit (31) for receiving information from the sensors (33, 35) and for deciding whether there is ice formation or risk of ice formation in the cooler (10, 15) and, if so, for controlling the coolant pump to be temporarily switched off or circulate a reduced flow of coolant through the cooler (10, 15) relative to a normal flow.

Abstract: A vehicle control system 10 includes a water pump 23 with an electromagnetic clutch, an oil relief device 25, an OCV 26, a water temperature sensor 31, and an ECU 11. The ECU 11 causes the electromagnetic clutch of the water pump 23 to be disengaged on the basis of the detection result detected by the water temperature sensor 31, and stops the coolant circulation. The ECU 11 instructs the OCV 26 to adjust the lubricant pressure to low by an oil relief device 25. The ECU 11 determines whether or not the adjustment of the lubricant pressure to low by the oil relief device 25 is stopped on the basis of the detection result detected by the water temperature sensor 31 when the engagement of the electromagnetic clutch of the water pump 23 continues for a given period.

Abstract: A cooling system includes a cooling portion for flowing a coolant therethrough, a coolant sensitive sensor portion detecting a temperature of the coolant, a heat exchanging device using a heat of the coolant, a circulation flow varying device for varying a circulation flow, a circulation path for flowing the coolant therethrough, and a controller for regulating the circulation flow by controlling the circulation flow varying device while referring to the temperature of the coolant upon a receipt of a request for a requested flow from the heat exchanging device. The controller determines a condition for warming-up when the warming-up of the engine is performed in accordance with the temperature of the coolant, controls the circulation flow varying device for warming-up the engine without circulating the coolant, and increases the circulation flow to the requested flow for a predetermined period of time when the requested flow is requested during the warming-up.

Abstract: A method is provided for the control of a switchable water pump for a water cooling circuit in an internal combustion engine. The method includes, but is not limited to monitoring a parameter representative of the cylinder head temperature and, in case the temperature is below a predetermined value, perform at least an on-off cycle for the switchable water pump. The on-off cycle, includes, but is not limited to at least a first phase in which the water pump is switched OFF for a time period T1 and a second phase in which the water pump is switched ON for a time period T2.

Abstract: In one embodiment, an apparatus is disclosed for heating a reductant delivery line using coolant from an internal combustion engine where the reductant delivery line receives reductant from a reductant tank and a portion of a coolant line is positioned within the reductant tank. The apparatus includes a coolant temperature module that is configured to determine a reductant tank outlet coolant temperature target. Additionally, the apparatus includes a coolant flow rate module that is configured to generate a coolant valve flow rate command and transmit the command to a coolant valve. The coolant valve is controllable to regulate the flow rate of coolant through the coolant line. The coolant valve flow rate command is based on the reductant tank outlet coolant temperature target, a reductant tank inlet coolant temperature, and a reductant tank reductant temperature.

Abstract: An internal combustion engine control apparatus includes: a fuel injector; a cooling fan of a radiator that radiates the heat of coolant in a coolant passage in the internal combustion engine; a flow rate control mechanism that variably controls the flow rate of the coolant; an abnormality detector that detects an abnormality of the cooling fan; and a controller that controls the amount of fuel injected from the fuel injector to the internal combustion engine and the operation of the flow rate control mechanism in accordance with the result of the abnormality detector.

Abstract: A method for controlling a marine engine uses a flow regulating valve in combination with a solenoid operated two position control valve to regulate the flow of cooling water through exhaust system components. Temperatures are measured at the components, such as within the cooling jacket of exhaust manifolds, and a microprocessor compares the measured temperatures to desired ranges. When the temperatures exceed upper limits, additional flow is directed from a pump to the exhaust system components. When the temperatures are below desired flow thresholds, the flow of the water in the pump is restricted in order to allow the exhaust system components to rise in temperature.

Abstract: An arrangement for a supercharged combustion engine for preventing ice formation in a cooler. A first cooling system with a circulating coolant. A second cooling system with a circulating coolant which during normal operation of the combustion engine is at a lower temperature than the coolant in the first cooling system. The cooler in which a gaseous medium for the engine and which contains water vapour is intended to be cooled by the coolant in the second cooling system. A heat exchanger. A valve which can be placed in a first position wherein coolant from at least one of the cooling systems is prevented from flowing through the heat exchanger and in a second position wherein coolant from both of the cooling systems flows through the heat exchanger so that the coolant in the second cooling system is warmed by the coolant in the first cooling system.

Abstract: In one aspect, the present invention is directed to an apparatus for controlling coolant (e.g., water-based liquid) level of an engine, the apparatus comprising: a metering system, for metering coolant level in the cooling system of the engine; an auxiliary reservoir of the coolant; and a conveying mechanism, for conveying coolant from the reservoir to the cooling system upon indicating, from the coolant level, absence of coolant in the cooling system. The conveying mechanism may be activated manually as well as automatically. The gauge may be deployed at the dashboard of the vehicle in which the apparatus is installed.

Abstract: This thermostat (1) comprises a body (10) which comprises a one-piece metal part (11) including simultaneously, in succession along the axis (X-X) of a thermostatic element (20) of the thermostat, a transverse tab (12) against which the piston (22) of this element can bear, a tubular part (13) centred on this axis and defining a shut-off seat (13A), and two support arms (14) supporting a return spring (40) for returning this element, which arms extend lengthwise more or less in the axial direction of the element and each delimits, at their opposite end (14A) to the tubular part, a surface (14A1) for contact with the spring against which surface the compressed spring is pressed.

Abstract: A drive component for driving an electric water pump for causing engine coolant to flow is mounted in an engine compartment. When the ignition is off and the temperature of a exhaust heat recovery device is above a temperature, an ECU estimates a peak temperature in the engine compartment after the stop of the engine. When the peak temperature is above a temperature, the ECU stops the engine and drives the electric water pump and an electric fan for cooling the drive component for driving the electric water pump.

Abstract: The present invention relates to a cooling system for an internal combustion engine. The cooling system can be used in a hybrid electric vehicle. The system includes electric pumps in fluid communication with the engine and a control unit that governs the pumps. The pumps can be configured to supply fluid to either a cylinder block or cylinder head and backflow fluid through either the cylinder block or cylinder heads. Various arrangements of electrical and mechanical pumps are disclosed to control fluid flow and pressure.

Abstract: When knocking occurs, a control apparatus for an internal combustion engine increases the rotational speed of a pump to increase the flow rate of a coolant supplied to an area near a combustion chamber wall surface, and controls an actual mechanical compression ratio to a low mechanical compression ratio lower than a mechanical compression ratio set based on the load of the engine. Thus, the pressure of end gas is decreased, and occurrence of knocking is suppressed. Then, the actual mechanical compression ratio is returned to the mechanical compression ratio at a time point at which the temperature of the combustion chamber wall surface has been sufficiently decreased due to the increase in the rotational speed. Thus, occurrence of knocking is suppressed while avoiding the situation where the actual mechanical compression ratio continues to be controlled to the low mechanical compression ratio that is lower than the mechanical compression ratio.

Abstract: A control device for use in the engine compartment or in the transmission of a motor vehicle. The control device has a housing comprising a housing section for a control unit. The housing also has a line section for the motor or transmission fluid. The line section is thermally coupled to the housing section for the control unit. Such a control device and a cooling arrangement therefore ensure that the electronic components in the control device are cooled such that a pre-determined temperature limit for the electronic components is not exceeded.

Abstract: An onboard cooling system diagnostic strategy utilizes at least one temperature sensor fluidly positioned between an electronically controlled engine and a thermostat. The diagnostic algorithm operates by monitoring coolant temperature during engine startup. By comparing the actual coolant temperature during engine start-up to a predicted coolant temperature that should occur if no cooling system error is present, a cooling system fault condition may be identified. If a cooling system fault is detected, the diagnostic logic may activate the engine cooling fan or intrusively open an electrically controlled thermostat while monitoring the coolant temperature response to the intrusive action. If there is a substantial change in coolant temperature responsive to the intrusive action, this phenomenon can be utilized to correctly distinguish between a thermostat failure and a vehicle configuration error corresponding to an overcooled vehicle.

Abstract: A water pump is driven by a driving force generated by an internal combustion engine, and generates a larger driving force as a pressure introduced into a pressure chamber becomes higher. The pressure chamber is connected to a VSV through a first passage. A portion of an intake passage, which is located downstream of a throttle valve, is connected to the VSV through a second passage. An atmospheric pressure space is connected to the VSV through a third passage. In the VSV, the volume of wax in a temperature-sensitive case is increased to increase the ratio of the cross sectional area of an opening portion of the third passage, which is connected to the first passage, to the cross sectional area of an opening portion of the second passage, which is connected to the first passage, as the temperature of a coolant for the internal combustion engine increases.

Abstract: A cooling apparatus that cools with coolant a subject of cooling, which is a heat source. The cooling apparatus includes a cooling circuit, an electric pump, a switching section, and a control section. Through circulation of the coolant, air in the cooing circuit is caused to flow to an air bleeding portion and is discharged from the cooling circuit through the air bleeding portion. The switching section is capable of switching the operation mode of the electric pump between a normal mode and an air bleeding mode for collecting air in the cooling circuit to the air bleeding portion. During the air bleeding mode, the control section is capable of controlling the electric pump to change a coolant displacement from the electric pump according to a change pattern that allows stagnant air in sections of the cooling circuit to flow to the air bleeding portion.

Abstract: A cooling system for a liquid cooled internal combustion engine having coolant passages and a heat exchanger selected to operate the engine cooling system in the region of nucleate boiling. A sensor detect the presence of nucleate boiling and a pump and pressure relief valve responsive to the sensor maintain the coolant system pressure at a level marinating optimum nucleate boiling to increase heat flux from the engine and reduce overall size of the system.

Abstract: A medium circulating apparatus of engine oil, which improves startability and warm up ability of an internal combustion engine, includes a microbubble generator that generates microbubbles and mixes the microbubbles into the circulating engine oil. Further, the medium circulating apparatus includes a medium temperature acquiring unit that acquires a temperature of the engine oil. The microbubbles are generated by the microbubble generator when the temperature of the engine oil is less than or equal to a predetermined value in order to decrease a viscosity, a heat conductivity, and a heat capacity of the engine oil in which the microbubbles are mixed.

Abstract: A system and method for removing gases from an engine coolant system. In one embodiment, the system includes a fluid system that is operable to collects gas, and a gas collection system coupled to the fluid system. The system also includes a venturi pump system coupled to the fluid system and to the collection system, where the venturi pump system is operable to extract the gas from the fluid system via the collection system.

Abstract: A method for controlling an engine output with at least two actuators, including applying inputs to actuators which regulate a variable of an engine, evaluating the response of the system, determining the ability of the actuators to change the engine variable, determining the capability of the actuators to reject a disturbance, calculating an optimum actuator feedforward control function based upon the ability and capability determined and controlling the actuators using the calculated function and a feedforward control algorithm.

Abstract: A variable flow coolant pump for an engine of a motor vehicle comprises a pump housing defining a fluid chamber. The fluid chamber includes a fluid inlet and a fluid outlet for providing flow of coolant through the housing. An impeller is rotationally supported in the fluid chamber between the inlet and the outlet for pumping coolant through the housing. An engine driven shaft is disposed within the housing for supporting the impeller and rotating the impeller about a longitudinal axis. An electromagnetic field generator selectively produces a magnetic field that moves the impeller axially along the shaft between a first position and a second position which selectively changes the amount of coolant flow through the housing between the fluid inlet and the fluid outlet.

Abstract: A cooling system for a liquid cooled internal combustion engine having coolant passages and a heat exchanger selected to operate the engine cooling system in the region of nucleate boiling. A sensor detect the presence of nucleate boiling and a pump and pressure relief valve responsive to the sensor maintain the coolant system pressure at a level marinating optimum nucleate boiling to increase heat flux from the engine and reduce overall size of the system.

Abstract: An ECU executes a program including a step of, if an engine is not in a cold state, controlling electric power to be supplied to an electric water pump such that a flow rate requested at the engine is obtained, a step of, if the engine is in the cold state and a heater is not requested to operate, providing control such that the electric water pump is stopped, and a step of, if the engine is in the cold state and the heater is requested to operate, controlling the electric power to be supplied to the electric water pump such that the flow rate is set to the highest one of the flow rate requested at the engine, a flow rate requested at a heater core, and a flow rate requested at an exhaust heat recovery device.

Abstract: An internal combustion engine has a variable speed coolant pump which is operated at a variable duty-cycle at lower coolant temperatures, while transitioning to a predetermined fixed speed during a final warmup period of operation, and finally to a select-speed operation at one of a selected number of steady state operating speeds selected as a function of at least engine load.