Method and system for an engine assembly

Methods and systems are provided for an internal combustion engine assembly comprising a water pump driven by a crankcase venting system. In one example, a method may include adjusting a transmission ratio of a magnetic transmission in response to a temperature of an engine, wherein the magnetic transmission connects a water pump to a crankcase venting system of the engine.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to German Application No. 102019202339.8 entitled “METHOD AND SYSTEM FOR AN ENGINE ASSEMBLY”, and filed on Feb. 21, 2019. The entire contents of the above-listed application are hereby incorporated by reference for all purposes.

FIELD

The present invention relates to methods and system for an internal combustion engine assembly comprising a water pump driven by a crankcase venting system.

In a crankcase of a combustion engine, crankcase venting gases (blow-by gases) occur, which are discharged from the crankcase via a vent system of the combustion engine and are introduced into an induction tract of the combustion engine, in particular for environmental reasons. A pressure difference between the crankcase and the induction tract can be used for this purpose. The vent system has a vent line from the crankcase to the induction tract, where an oil mist separator is arranged to separate an oil mist contained in the blow-by gases from the blow-by gases. The deposited oil is then returned to the crankcase by the oil mist separator.

DE 101 28 465 A1 discloses an oil separator for crankcase venting of a combustion engine, with a radial feed of blow-by gas and chambers for separating oil and air by rotation. In the oil separator, a conveying means is arranged for conveying the blow-by gas, which has at least a first and second vane wheel. The vane wheels are arranged on a common shaft. The shaft is arranged coaxially to a shaft of a water pump, wherein the two shafts are rotationally fixedly interconnected and are driven by a common drive.

U.S. Pat. No. 7,524,357 B2 discloses an oil mist separator for a gas turbine engine. The oil mist separator has a centrifugal separation stage with a fluid connection to a downstream electrostatic separation stage. The centrifugal separation stage drives an electric generator for driving the electrostatic separation stage.

DE 20 2015 105 904 U1 discloses a pump separator with a separator for separating liquid components from a liquid-solid mixture, a self-priming pump that is designed to convey the liquid-solid mixture into the separator, and a drive shaft, wherein the separator and the pump are driven by the drive shaft.

US 2010/142 962 A2 discloses a magnetic transmission for a vehicle. The magnetic transmission has a first magnet rotor, a second magnet rotor and a rotatable pole shoe element, wherein the rotatable pole shoe element is magnetically coupled to the first magnet rotor and the second magnet rotor. The rotatable pole shoe element works as a control rotor, which is arranged in such a way that in operation a change in the transmission ratio between the magnetic rotors results. The magnetic transmission also has a transmission control means for varying the transmission ratio.

The inventors herein have recognized it is possible provide a combustion engine with a compact and light-weight design by driving a water pump of a cooling circuit of an engine system with an oil mist separator via a magnetic transmission. In one example, the method for the engine may comprise adjusting a transmission ratio of a magnetic transmission in response to a temperature of an engine, wherein the magnetic transmission connects a water pump to a crankcase venting system of the engine. In particular, the magnetic transmission connects the water pump to a shaft of an oil mist separator coupled with an electric drive in the crankcase venting system. In this way, the water pump of a cooling circuit of the engine is powered by the electric drive in the crankcase venting system, and does not require a separate drive. Thus, the engine assembly requires a smaller installation space and lower installation cost, providing a lighter, more compact, and less expensive assembly comparing to conventional internal combustion engines.

In another example, the magnetic transmission can have at least one first magnetic rotor rotationally fixedly connected to the shaft of the oil mist separator with mutually circumferentially offset permanent magnets with alternating polarity, at least one second magnetic rotor rotationally fixedly connected to a rotor of the water pump with mutually circumferentially offset permanent magnets with alternating polarity and at least one rotatably arranged modulator ring arranged radially between the two magnetic rotors. The first magnetic rotor may also be embodied such that the permanent magnets are arranged directly on the shaft of the oil mist separator. By moving the modulator ring, the magnetic flux between the magnetic rotors is varied, which leads to a variation of the transmission ratio of the magnetic transmission. The modulator ring is moved into the magnetic field so that the magnetic field is weakened or moved out of the magnetic field so that the magnetic field is strengthened, so that the rotation speed of the water pump is adjustable. It is true that magnetic losses occur, i.e. heat generation takes place. However, this is no longer harmful, as the water pump can absorb and dissipate this heat due to the circulating coolant. The magnetic field within the electromagnetic transmission is also varied by different currents, so that different speeds are adjustable, wherein even rotational direction changes are possible.

In another example, the electric drive of the oil mist separator rotates the shaft at a constant rotational speed, and the method further comprises adjusting a current supply to the electric drive in response to the transmission ratio of the magnetic transmission.

In another example, the electric drive of the oil mist separator does not rotate the shaft at a constant rotational speed. Further, when the oil mist separator is not operating, such as during DFSO (deceleration fuel shut off), in response to the cooling water temperature above a threshold temperature, the electric drive of the oil mist separator is turned on.

In another example, the water pump may have at least one rotor that is in contact with the cooling water. The water pump may be embodied as a centrifugal pump, for example Preferably, an air gap is provided in each case between the first magnetic rotor and the modulator ring and between the modulator ring and the second magnetic rotor, whereby the magnetic transmission does not generate friction losses. Since the magnetic transmission has no roller bearings, no seals are required.

In another example, the oil mist separator is an electric oil mist centrifugal separator in which the oil contained in the blow-by gas is separated from the blow-by gas by means of centrifugal forces, for which the oil mist separator has the centrifugal separator that rotates in operation. The electric drive of the oil mist separator has an electric motor. The shaft serves as an output shaft of the electric drive. The centrifugal separator may, for example, have multiple separating lamellas radially protruding from the shaft and arranged axially spaced apart from each other.

In another example, the internal combustion engine can be a charged or uncharged petrol engine or diesel engine. The crankcase vent system has at least one blow-by gas feed line from the crankcase of the combustion engine to the oil mist separator, at least one gas discharge line for conducting purified gas from the oil mist separator to an induction manifold of the combustion engine and at least one oil drain pipe from the oil mist separator to the crankcase. The cooling circuit has at least one water supply line from a cooler of the cooling circuit to the water pump, at least one water outlet line from the water pump to the internal combustion engine for cooling the internal combustion engine and at least one water pipe from the combustion engine to the cooler.

In another example, the internal combustion engine has at least one controller connected to the magnetic transmission, which is set up to control the magnetic transmission, i.e. the electromagnetic transmission, in such a way that a transmission ratio of the magnetic transmission is varied depending on a cooling requirement detected by sensor of an internal combustion engine of the combustion engine. According to this, the transmission ratio of the magnetic transmission can be varied to increase the speed of the water pump if a higher cooling requirement of the internal combustion engine is determined. Likewise, the transmission ratio of the magnetic transmission can be varied to reduce the speed of the water pump if a lower cooling requirement of the internal combustion engine is determined. The cooling requirement of the internal combustion engine can be determined by means of the controller based on measuring signals of at least one temperature sensor assigned to the combustion engine.

DETAILED DESCRIPTION

The following description relates to methods for operating an engine assembly.FIG. 1shows a schematic depiction of an example engine system with a cooling circuit comprising a water pump and a crankcase venting system comprising an oil mist separator. The water pump and the oil mist separator connected by a magnetic transmission.FIG. 2shows a flow chart of an example method of operating the engine assembly. In response to a cooling water temperature, a transmission ratio of the magnetic transmission is adjusted.

FIG. 1shows a schematic depiction of an example engine system with a cooling circuit comprising a water pump and a crankcase venting system comprising an oil mist separator. Engine system1has an internal combustion engine2with a crankcase3, a crankcase venting system4for venting the crankcase3, and a cooling circuit5for cooling the internal combustion engine2.

In addition, the engine system1has an assembly6, which includes a water pump7of the cooling circuit5and an oil mist separator8of the crankcase venting system4. The water pump7and the oil mist separator8are arranged in a common housing9.

The oil mist separator8has an electric drive10, a shaft11that can be driven by the electric drive10and a centrifugal separator12rotationally fixedly connected to the shaft11. The centrifugal separator12has several separating lamellas13that protrude radially from the shaft11.

The oil mist separator8is connected by a blow-by gas supply line14to the crankcase3and by a gas outlet15line to an induction manifold16of the combustion engine1. Furthermore, the oil mist separator8is connected to the crankcase3via an oil drain pipe17.

The water pump7is connected via a water feed line18to a cooler19of the combustion engine1and via a water outlet line20to the internal combustion engine2.

The assembly6also has a magnetic transmission21connecting the shaft11to the water pump7for drive purposes. The magnetic transmission21has a first magnet rotor that is not shown that is rotationally fixedly connected to the shaft11, a second magnet rotor that is not shown that is rotationally fixedly connected to a rotor22of the water pump7and coaxially arranged relative to the first magnet rotor, and a modulator ring that is not shown that is arranged radially between the magnet rotors and that can be displaced in the circumferential direction for varying the magnetic flux between the magnet rotors. The permanent magnets can also be arranged directly on the shaft11, thus forming the first magnet rotor.

The internal combustion engine1also has controller23connected to the magnetic transmission21and set up to control the magnetic transmission21in such a way that a transmission ratio of the magnetic transmission21is varied depending on a cooling demand of the internal combustion engine2sensed by a temperature sensor24arranged on the internal combustion engine2. Alternatively, the temperature sensor24is arranged in other locations of the cooling circuit5, such as upstream of the cooler19.

Turning now toFIG. 2, an example method of operating an engine system is shown in method200. Instructions for carrying out method200and the rest of the methods included herein may be executed by the controller based on instructions stored on a memory of the controller23and in conjunction with signals received from sensors of the engine system, such as the temperature sensor24described above with reference toFIG. 1.

At201, method200determines whether the engine is operating. If the engine is operating, method200moves to step202. Otherwise, at step208, method200moves to step208to exits the routine.

At202, method200determines if the oil mist separator is turned on. As an example, during an engine cold start, the blow-by gas may not contain oil mist due to a lower temperature. Therefore, the oil mist separator is turned off. As another example, after engine warm-up, temperature of the oil in crankcase may be high enough to form oil mist and mix with the blow-by gas. In this case, the oil mist separator is turned on to separate the oil mist contained in the blow-by gas. If the oil mist separator is turned on, method200moves to step205, wherein a transmission ratio of the magnetic transmission and a current supply to the electric drive are adjusted. If the oil mist separator is turned off, method200moves to step203, wherein temperature of cooling water is compared to a threshold temperature.

At step203, method200compares a cooling water temperature and a threshold temperature. The cooling water temperature is determined by a sensed signal from the temperature sensor24. As described above forFIG. 1, the temperature sensor24may be coupled to the internal combustion engine2. Alternatively, the temperature sensor24may be arranged, but not limited to, upstream of the cooler19or downstream of the water pump7. If the cooling water temperature is not above a threshold temperature, method200moves to step208to exits the routine. If the cooling water temperature is above a threshold temperature, method200moves to step204.

At step204, method200turns on the electric drive of the oil mist separator. By turning on the electric drive of the oil mist separator, the oil mist separator starts operating, and the shaft coupled to the electric drive starts rotating. In one example, the shaft rotates at a constant rotational speed.

At step205, method200adjusts a transmission ratio of the magnetic transmission and a current supply to the electric drive. In particular, at step206, method200adjusts the transmission ratio of the magnetic transmission in response to the cooling water temperature. Specifically, method200increases the transmission ratio in response to an increasing cooling water temperature, and decreases the transmission ratio in response to a decreasing cooling water temperature.

Adjustment of the transmission ratio is achieved by moving the modulator ring of the magnetic transmission. For example, when the modulator ring is moved into the magnetic field, the magnetic field is weakened. As a result, the transmission ratio of the magnetic transmission is reduced, and the rotational speed of the water pump is hence reduced. In an another example, when the modulator ring is moved away from the magnetic field, the magnetic field is strengthened. As a result, the transmission ratio of the magnetic transmission is increased, and the rotational speed of the water pump is hence increased.

At step207, method200adjusts a current supply to the electric drive. As described above, the shaft of the oil mist separator rotates at a constant rotational speed. Therefore, as the speed of the water pump increases, more power is transferred from the shaft to the water pump. Consequently, a current supply to the electric drive is increased to maintain the constant rotational speed of the shaft. On the other hand, as the speed of the water pump decreases, the current supply to the electric drive may be decreased due to a lower power command.

The technical effect of coupling a water pump of a cooling circuit of the engine to an oil mist separator of a crankcase venting system may be providing rotational power to the water pump without using an additional motor for the water pump. In this way, the engine assembly requires less space as well as lower cost, and may provide a more compact and cheaper engine assembly.

A method for an engine includes adjusting a transmission ratio of a magnetic transmission in response to a temperature of an engine, wherein the magnetic transmission connects a water pump to a shaft of an oil mist separator of the engine.

A method for an engine further includes in response to a cooling request of an engine, adjusting a magnetic transmission connecting a water pump and a shaft of an oil separator of the engine.

An engine system, comprising a crankcase, a crankcase venting system coupled to the crankcase, an oil mist separator in the crankcase venting system, wherein the oil mist separator includes an electric drive and a shaft driven by the electric drive, a cooling circuit including a water pump, a magnetic transmission coupled to the shaft, the magnetic transmission connecting the shaft to the water pump, and a controller configured with computer readable instructions stored on non-transitory memory for adjusting a transmission ratio of the magnetic transmission in response to a temperature of the engine