METHOD FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE

Abstract

A method for controlling an internal combustion engine, comprising an electric lubricant pump and a turbocharger, is provided. The method includes determining whether the internal combustion engine is operating in a normal operating mode, in which the turbocharger's boost pressure exceeds a boost pressure threshold, or in a low-demand operating mode, in which the turbocharger's boost pressure does not exceed the boost pressure threshold. If it is determined that the internal combustion engine is operating in the normal operating mode, the method includes supplying electrical power to the electric lubricant pump to cause lubricant to be supplied to the turbocharger at a pressure of at least a predetermined lubricant pressure.If it is determined that the internal combustion engine is operating in the low-demand operating mode, the procedure includes reducing the electrical power supplied to the electric lubricant pump in order to lower the lubricant pressure to a leakage prevention pressure that is lower than the predetermined lubricant pressure.

Description

Realm of Revelation

[0001] The present disclosure relates to turbochargers. In particular, the present disclosure relates to the lubrication of a turbocharger. State of the art

[0002] Turbochargers typically comprise a compressor and a turbine. The compressor may be connected to the turbine via a bearing section that includes a bearing. Turbocharger bearings may be lubricated with a continuous supply of lubricant (e.g., oil) to the bearing surfaces to maintain shaft stability and prevent excessive wear of the bearing surfaces.

[0003] To ensure adequate lubrication, the lubricant can be supplied to the bearing section under pressure. If the turbocharger bearing is operated without sufficient lubricant pressure, the bearing surfaces can wear and / or the bearing can seize. Low lubricant pressure occurs particularly when starting an internal combustion engine, as the lubricant pressure can drop when the engine is at rest.

[0004] The lubricant flow can be supplied by a pump connected to an internal combustion engine. The pump is usually driven by the internal combustion engine. During normal operation of the turbocharger / internal combustion engine, the lubricant pressure supplied to the turbocharger is therefore dependent on the engine speed of the internal combustion engine. Brief description

[0005] According to a first aspect of the disclosure, a method for controlling an internal combustion engine is provided, comprising an electric lubricant pump and a turbocharger. The method includes determining whether the internal combustion engine is operating in a normal operating mode, in which the turbocharger's boost pressure exceeds a boost pressure threshold, or in a low-demand operating mode, in which the turbocharger's boost pressure does not exceed the boost pressure threshold. If it is determined that the internal combustion engine is operating in the normal operating mode, the method includes supplying electrical power to the electric lubricant pump to cause lubricant to be supplied to the turbocharger at a pressure of at least a predetermined lubricant pressure.If it is determined that the internal combustion engine is operating in the low-demand operating mode, the procedure includes reducing the electrical power supplied to the electric lubricant pump in order to lower the lubricant pressure to a leakage prevention pressure that is lower than the predetermined lubricant pressure.

[0006] According to the procedure, the turbocharger is supplied with lubricant by an electric lubricant pump. Under normal operation of the internal combustion engine, lubricant can be supplied to the turbocharger at a predetermined pressure. However, during low-demand operation of the internal combustion engine, the reduction in turbocharger boost pressure can lead to an increased pressure differential between a bearing section of the turbocharger (where the lubricant flows) and the compressor and / or turbine of the turbocharger (which normally operate under pressure). This increased pressure differential can cause lubricant to leak from the bearing section into the compressor and / or turbine. The introduction of lubricant into the turbocharger's airflow can damage downstream components such as the aftertreatment system.According to the first aspect of the procedure, in low-demand operating mode the lubricant pressure can be reduced to a leakage prevention pressure that is lower than the predetermined lubricant pressure in order to decrease the pressure differential. This, in turn, reduces or prevents lubricant from leaking into the compressor and / or turbine of the turbocharger. Such control of the lubricant pressure is possible because the lubricant is pressurized using an electric lubricant pump whose pumping capacity can be controlled independently of the operation of the internal combustion engine.

[0007] According to a second aspect of the disclosure, a control system for an internal combustion engine is provided, comprising an electric lubricant pump and a turbocharger. The control system is designed to determine whether the internal combustion engine is operating in a normal operating mode, where the turbocharger boost pressure is above a boost pressure threshold, or in a low-demand operating mode, where the turbocharger boost pressure is not greater than the boost pressure threshold. If the control system determines that the internal combustion engine is operating in the normal operating mode, the control system is designed to cause electrical power to be supplied to the electric lubricant pump to cause lubricant to be supplied to the turbocharger at a pressure of at least a predetermined lubricant pressure.If the control system determines that the internal combustion engine is operating in low-demand mode, the control system is designed to reduce the electrical power supplied to the electric lubricant pump in order to reduce the lubricant pressure to a leakage prevention pressure that is lower than the predetermined lubricant pressure.

[0008] Thus, the control of the second aspect can cause an internal combustion engine, which has a turbocharger and an electric lubricant, to carry out the procedure of the first aspect.

[0009] According to a third aspect of the disclosure, an internal combustion engine is provided for a machine. The internal combustion engine includes a control unit according to the second aspect, a turbocharger, and an electric lubricant pump designed to supply lubricant to the turbocharger.

[0010] Thus, the combustion engine of the third aspect can perform the procedure of the first aspect. Brief description of the drawings

[0011] Embodiments of this disclosure are now described with reference to the following figures, in which: - Fig. 1 a block diagram of an internal combustion engine and a turbocharger according to an embodiment of the present disclosure; - Fig. 2 is a schematic representation of a lubricant leakage path in a turbocharger; - Fig. 3 a block diagram of a method for controlling an internal combustion engine according to an embodiment of this disclosure; and - Fig. 4 is a diagram that shows a relationship between lubricant pressure and engine speed. Detailed description

[0012] According to one embodiment of the disclosure, an internal combustion engine 1 is provided. Fig. Figure 1 represents a schematic system diagram of the internal combustion engine 1. As in Fig. As shown in Figure 1, the internal combustion engine 1 includes a turbocharger 10. The internal combustion engine 1 can be provided as part of a machine (in Fig. (1 not shown). The machine could be, for example, a generator or a work vehicle such as an excavator, a wheel loader, a bulldozer, a telescopic handler, a tractor, or the like.

[0013] As in Fig. As shown in Figure 1, the turbocharger 10 comprises a compressor 20, a bearing section 30, and a turbine 40. As shown in the system diagram of Fig. As shown in Figure 1, the compressor 20 of the turbocharger 10 can receive an intake gas, for example from an air intake (in Fig. (1 not shown) is designed. The compressor 20 of the turbocharger 10 can supply the compressed intake gas directly to the combustion engine 1 or via a (in Fig. (1 not shown) aftercooler. The turbine 40 of the turbocharger 10 can receive gas from the combustion engine 1 and deliver gas to a (in Fig. 1 (not shown) aftertreatment system designed. The flow of the various gases to and from the combustion engine 1 and turbocharger 10 is in Fig. 1 indicated by dashed lines.

[0014] The bearing section 30 comprises a bearing 32 that connects a turbine blade assembly (not shown) of the turbine 40 to a compressor impeller (not shown) of the compressor 20. To reduce friction and to reduce or prevent wear of the bearing 32 and the associated surfaces of the bearing section 30 / turbocharger 10, the bearing section 30 of the turbocharger 10 can be provided with a lubricant supply. To reduce or prevent wear of the bearing 32, the bearing section 30 can be supplied with lubricant at a lubricant pressure that is at least at a predetermined lubricant pressure. If the turbocharger 10 is operated at a lubricant pressure below the predetermined lubricant pressure, the bearing 32 (or the surfaces of the bearing section 30) may not be sufficiently lubricated, leading to disproportionate wear of the respective surface.Prolonged operation of the turbocharger 10 at a lubricant pressure below the predetermined lubricant pressure may reduce the service life of the turbocharger 10.

[0015] As shown in the system diagram of Fig. As shown in Figure 1, the internal combustion engine 1 can include a lubricant reservoir 3 and an electric lubricant pump 4. The electric lubricant pump 4 can be in fluid communication with the lubricant reservoir 3 and the bearing section 30 of the turbocharger 10. The electric lubricant pump 4 can be designed to pump lubricant from the lubricant reservoir 3 to the bearing section 30 for lubricating the bearing 32. The bearing section 32 can also be in fluid communication with the lubricant reservoir 3 to provide a return path 6 for lubricant to the lubricant reservoir 3. During normal operation of the internal combustion engine 1 (e.g., when the internal combustion engine has been ready for operation for at least a few minutes), the electric lubricant pump 4 can pump lubricant from the lubricant reservoir 3 to the turbocharger 10. Lubricant can circulate through the bearing section 30 of the turbocharger 10 and via the Fig. 1 return to the lubricant container 3 via the schematically depicted return path 6.

[0016] According to this disclosure, an electric lubricant pump 4 can be understood to be a pump that can be driven by electrical energy for pumping lubricant. In some embodiments, the electric lubricant pump 4 can comprise an electric motor (not shown), wherein the electric motor is designed to receive electrical energy (e.g., from a battery connected to the motor, for example, a battery of the internal combustion engine 1). The electric lubricant pump 4 can be designed to pump lubricant under pressure, wherein the pressure can be controlled by the electrical energy supplied to the electric lubricant pump 4. A control unit 5 of the internal combustion engine 1 can control the electrical energy supplied to the electric lubricant pump 4 in order to control the pressure of the lubricant supplied to the internal combustion engine 1 / turbocharger 10.It is therefore understood that the electric lubricant pump 4 cannot be directly driven by the mechanical energy generated by the internal combustion engine 1. In particular, the power output of the electric lubricant pump 4 must not depend on the engine speed of the internal combustion engine 1.

[0017] As in Fig. As shown in Figure 1, the electric lubricant pump 4 can be configured to pump lubricant into the bearing section 30. During normal operation, the electric lubricant pump can be configured to supply lubricant to the bearing section 30 at a predetermined lubricant pressure. The predetermined lubricant pressure can be selected to ensure that the lubricant is supplied to the bearing section 30 at a pressure sufficient to lubricate all relevant surfaces of the bearing section 30 and the turbocharger 10. Providing lubricant at sufficient pressure reduces or prevents excessive wear of the bearing 32 when the turbocharger is in operation. Therefore, the predetermined lubricant pressure can be greater than or equal to a first lubricant pressure. In some embodiments, for example, the predetermined lubricant pressure can be at least 200 kPa, 220 kPa, 240 kPa, 260 kPa, 280 kPa, or 300 kPa.In some embodiments it may be desirable to supply lubricant to the turbocharger 10 at a pressure that does not significantly exceed the pressure required to lubricate the turbocharger 10 in order to operate the internal combustion engine 1 and the electric lubricant pump 4 efficiently.

[0018] In some embodiments, the electric lubricant pump 4 may be designed to supply lubricant not only to the turbocharger 10 but also to other components connected to the internal combustion engine 1. In such embodiments, the predetermined lubricant pressure may be selected based on a lubricant pressure that provides sufficient lubrication for the other components and the turbocharger. Therefore, it should be understood that the predetermined lubricant pressure may be a lubricant pressure suitable for providing sufficient lubrication for the components that are in fluid contact with the electric lubricant pump 4 during the normal operation of the turbocharger 10.

[0019] It is important to understand that when the internal combustion engine 1 is at a standstill (i.e., at an engine speed of 0 revolutions per minute (rpm)), the lubricant pressure in the bearing section 30 (or another part of the lubrication system of the internal combustion engine 1) may fall below the predetermined lubricant pressure. Therefore, when starting up the internal combustion engine, a period of time (a start-up time) may be required for the lubricant pressure to reach the predetermined lubricant pressure before normal operation of the internal combustion engine 1 begins.

[0020] During normal operation, the controller 5 regulates the pressure of the lubricant supplied to the turbocharger 10, assuming that the turbocharger 10 is ready for operation. During operation, the compressor 20 and turbine 40 of the turbocharger 10 are pressurized to provide the turbo boost pressure for the internal combustion engine 1. In short, during normal operation of the turbocharger 10, the lubricant pressure in the bearing section 30 is balanced by the pressures in the compressor 20 and turbine 40, thus providing the turbo boost pressure during normal operation of the turbocharger 10.

[0021] Fig. Figure 2 shows a schematic cross-sectional representation of possible leakage paths for lubricant from the bearing section 30 of the turbocharger 10. As in Fig. As shown in Figure 2, the lubricant flows in normal operation from the bearing section inlet 33 to the bearing section outlet 34 through the bearing section 30. Under certain circumstances, lubricant may flow via the Fig. Leakage paths 2 shown from the bearing section 30 to the compressor 20 and / or to the turbine 40. In particular, lubricant can flow through a leakage path between the bearing section 30 and the compressor 20 along a path shown in Fig. Lubricant may flow through the specified leakage path 2 if there is a relatively large difference between the lubricant pressure in bearing section 30 and the pressure in compressor 20 (compared to the pressure difference during normal operation of turbocharger 10). Similarly, lubricant may flow through a leakage path between bearing section 30 and turbine 40 if there is a relatively large pressure difference between the lubricant pressure in bearing section 30 and the pressure in turbine 40. For example, turbocharger 10 may be prone to lubricant leakage if the lubricant pressure is at the predetermined pressure and turbocharger 10 is inoperable due to a fault with the turbocharger (such as when the turbo boost pressure is practically zero).In contrast, when the turbocharger 10 is operational (providing turbo boost pressure), the pressure difference between the predetermined lubricant pressure and the pressure in the compressor 20 / turbine 40 is relatively small, so lubricant does not flow along the leakage paths.

[0022] It is understood that the amount of lubricant flow along the in Fig. The leakage paths specified in 2 are significantly smaller than the lubricant flow from the inlet 33 to the outlet 34 of the bearing section 30, even at a relatively large pressure differential. If lubricant flows along one or more leakage paths, it can flow downstream of the turbocharger 10 into the internal combustion engine 1 and / or the aftertreatment system (not shown). Downstream lubricant flow is undesirable because it can cause downstream systems (internal combustion engine 1, aftertreatment system) to operate in unintended conditions, which can be time-consuming or costly to rectify. Therefore, according to this disclosure, a method 100 for controlling an internal combustion engine 1 is provided, which is directed towards reducing or preventing lubricant leakage into a turbocharger 10. The method 100 can be controlled by the control unit 5 of the turbocharger 10. Fig. The process is carried out using the combustion engine 1 shown in Figure 1. A block diagram of the process 100 is shown in Figure 1. Fig. 3 shown.

[0023] In step 101, method 100 includes determining an operating mode of the internal combustion engine 1. For example, the controller 5 can determine whether the internal combustion engine 1 is operating in a normal operating mode, in which the turbocharger boost pressure is above a boost pressure threshold, or in a low-demand operating mode, in which the turbocharger boost pressure is not greater than the boost pressure threshold. Therefore, the boost pressure threshold can indicate an operating condition of the turbocharger below which the pressure in the compressor 20 and / or turbine 40 is so high that lubricant leakage can occur. The controller 5 can determine the turbocharger boost pressure based on one or more pressure sensors (not shown) connected to the turbocharger. In some embodiments, the boost pressure threshold can be a predetermined (i.e., fixed) value.In some embodiments, the boost pressure threshold can be determined using a control map of the control unit, as explained below.

[0024] If it is determined that the internal combustion engine is operating in normal mode (step 102), the method includes supplying electrical power to the electric lubricant pump to ensure that lubricant is supplied to the turbocharger at a pressure of at least a predetermined lubricant pressure. Thus, in normal operation, the controller 5 controls the electric lubricant pump to supply lubricant to the turbocharger 10 at a predetermined lubricant pressure that provides adequate lubrication of the turbocharger 10. In some embodiments, the predetermined lubricant pressure may, for example, be at least 200 kPa.

[0025] In some embodiments, during normal operation, electrical power is supplied to the electric lubricant pump to cause lubricant to be supplied to the internal combustion engine at a pressure of at least one predetermined lubricant pressure, whereby the predetermined lubricant pressure can be controlled based on the engine speed of the internal combustion engine 1. Therefore, in some embodiments, the controller 5 can adjust the predetermined lubricant pressure based on the engine speed of the internal combustion engine 1 and / or other operating parameters of the internal combustion engine 1. For example, the controller 5 can be designed to increase the predetermined lubricant pressure when the engine speed increases above an idle speed to provide additional lubrication at higher engine speeds.

[0026] In an internal combustion engine that includes a mechanical lubricant pump (i.e., a pump driven by the mechanical power generated by the engine), an increase in engine speed can typically lead to an increase in lubricant pressure. To prevent the lubricant pressure from becoming excessively high, a mechanical lubricant pump may be connected to a pressure relief valve. The pressure relief valve can provide a return path for lubricant to a lubricant reservoir when a pressure threshold set by the valve is exceeded.

[0027] In some embodiments of the disclosure, the electric lubricant pump 4 can be controlled by the controller 5 in normal operating mode such that the lubricant pressure does not exceed a threshold pressure. Accordingly, the controller 5 can control the electric lubricant pump independently of the engine speed to provide functionality similar to a pressure relief valve. Therefore, in some embodiments, the lubrication system of the internal combustion engine 1 can be provided without pressure relief to simplify the system.

[0028] If the turbo boost pressure does not exceed the boost pressure threshold, the control unit determines that the combustion engine 1 is operating in low-demand mode (step 102 of Fig. 3) If it is determined that the internal combustion engine 1 is operating in the low-demand operating mode (step 103), the turbocharger 10 may be in a state where the pressure differential between the bearing section 30 and the compressor 20 and / or the turbine 40 could lead to lubricant leakage. To reduce or prevent lubricant leakage when the internal combustion engine 1 is operating in the low-demand operating mode (step 103), the method involves reducing the electrical power supplied to the electric lubricant pump 4 to reduce the lubricant pressure to a leakage prevention pressure that is lower than the predetermined lubricant pressure. By reducing the lubricant pressure to the leakage prevention pressure, the method 100 reduces the pressure differential between the bearing section 30 and the compressor 20 and / or the turbine 40 to reduce or prevent lubricant leakage.

[0029] In some embodiments, when operating in low-demand mode, electrical power can be supplied to the electric lubricant pump 4 to cause lubricant to be supplied to the internal combustion engine 1 at the leakage prevention pressure, the leakage prevention pressure being controlled based on the engine speed of the internal combustion engine 1. In some embodiments, the leakage prevention pressure may not exceed 90%, 80%, 70%, 60%, or 50% of the predetermined lubricant pressure. In some embodiments, the leakage prevention pressure may be selected based on the design of the turbocharger 10 and / or an operating speed of the turbocharger 10. In some embodiments, for example, the controller 5 may determine the leakage prevention pressure based on a control map of the controller 5 based on an operating speed of the turbocharger 10.

[0030] As in Fig. As shown in Figure 3, the procedure 100 can repeatedly determine the operating mode of the internal combustion engine 1 and control the lubricant pressure accordingly. Thus, after determining that the turbo boost pressure has dropped below the boost pressure threshold, the procedure can proceed to check whether the internal combustion engine has returned to normal operating mode based on the turbo boost pressure.

[0031] In some embodiments, the boost pressure threshold can be determined using a control map of the control unit. For example, the boost pressure threshold can vary depending on the power output of the internal combustion engine 1 or another suitable parameter of the internal combustion engine 1. In some embodiments, the boost pressure threshold can be determined based on a fuel quantity of the internal combustion engine 1 and an engine speed of the internal combustion engine 1.

[0032] According to some embodiments of the disclosure, when the controller 5 determines that the internal combustion engine 1 is operating in low-demand mode, it can reduce the lubricant to different pressures depending on the cause of the reduction in turbo boost pressure. Thus, the low-demand mode can comprise one operating mode or a plurality of operating modes (or sub-modes) that can be selected by the controller 5, as described below.

[0033] In some embodiments, determining whether the internal combustion engine 1 is operating in a low-demand operating mode includes determining whether the turbocharger 10 is operating in a fault mode. The fault mode of the turbocharger 10 can be determined if the turbocharger boost pressure is below a first boost pressure threshold. If the turbocharger 10 is determined to be operating in a fault mode, the lubricant pressure can be reduced to a fault leakage prevention pressure. The fault mode of the turbocharger 10 can be determined if a fault in the turbocharger 10 has rendered it effectively inoperable. Therefore, in some embodiments, the first boost pressure threshold may be approximately zero turbocharger boost pressure. In some embodiments, the fault mode can be determined if the turbocharger boost pressure is below a first boost pressure threshold and if the turbocharger speed 10 is below an operating speed threshold.For example, if the operating speed of turbocharger 10 is approximately zero, such an operating speed may indicate a fault with turbocharger 10.

[0034] In other embodiments, the fault mode of the turbocharger 10 can also be determined based on one or more parameters associated with the turbocharger 10 that can be received by the controller 5. As will be apparent to those skilled in the art, the controller 5 of the internal combustion engine 1 can be designed to monitor a multitude of parameters of the turbocharger 10 during the operation of the internal combustion engine 1. For example, the controller 5 can be designed to receive data indicating one or more of the following: the boost pressure of the turbocharger 10, the temperature of the turbocharger 10, a fault code indicating the operating state of the turbocharger 10, the pressure of the lubricant supplied to the turbocharger 10, the rotational speed of the turbocharger 10, a vibration signal from the turbocharger 10, and the intake vacuum for the turbocharger 10.The fault mode of turbocharger 10 can be determined by comparing one or more of the aforementioned parameters with a corresponding threshold value to identify the occurrence of a fault in turbocharger 10. By determining the fault mode of turbocharger 10 based on more than one sensor measurement (i.e., based on the turbo boost pressure and another sensor measurement), the controller 5 can reduce the risk of an incorrect determination of the fault mode due to a failure of a sensor associated with the calculation of the turbo boost pressure (e.g., failure of a pressure sensor).

[0035] If a fault mode of the turbocharger 10 is detected, the lubricant pressure of the electric lubricant pump 4 can be significantly reduced compared to the predetermined lubricant pressure. A significant reduction in lubricant pressure is possible because the turbocharger 10 is effectively no longer operational. For example, the fault leakage prevention pressure can be no more than 50%, 40%, 30%, 20%, or 10% of the predetermined lubricant pressure. In some embodiments, the lubricant supply to the turbocharger 10 can be completely interrupted to prevent lubricant leakage. For example, if the fault mode is detected, the controller 5 can be configured to close a turbo lubricant valve 8 (as in Fig. 1 shown), which may be designed to control the lubricant supply to the turbocharger 10 in order to prevent the lubricant supply to the turbocharger 10.

[0036] The fault mode of the turbocharger 10 can be determined when the control unit 5 detects a relative drop in the turbocharger boost pressure (and / or other related parameters of the internal combustion engine 1). In such an operating mode, the lubricant pressure can be reduced to the fault leakage prevention pressure to prevent or reduce the leakage of lubricant into the turbocharger 10 if a fault is detected in the turbocharger 10.

[0037] In some embodiments, determining whether the internal combustion engine 1 is operating in a low-demand operating mode may include determining whether the internal combustion engine 1 is operating in a component failure mode. The component failure mode can be determined based on whether the turbocharger boost pressure falls below a second boost pressure threshold. The second boost pressure threshold may be higher than the first boost pressure threshold (of the turbocharger 10 failure mode). The component failure mode can be determined if the controller 5 detects that a fault may exist in a component of the internal combustion engine (other than the turbocharger 10). Such a fault with a component of the internal combustion engine 1 may cause the turbocharger boost pressure to drop below a second boost pressure threshold. The second boost pressure threshold may be higher than the first threshold.This means that a component fault can be detected even if the turbocharger 10 is still operational (e.g., the turbo boost pressure is reduced but still greater than zero).

[0038] If the internal combustion engine 1 is detected as operating in component fault mode, its speed can be limited to a maximum first speed threshold. If the internal combustion engine 1 is detected as operating in component fault mode, its power output can be limited to a maximum first power output threshold. If the internal combustion engine 1 is detected as operating in component fault mode, the electrical power supplied to the electric lubricant pump 4 can also be limited so that the lubricant pressure does not exceed the leakage prevention pressure.Thus, in component failure mode, the internal combustion engine 1 can be operated at a reduced speed / power output to allow it / the machine to reach a state / location where further maintenance can be performed. The reduced speed / power operation of the internal combustion engine 1 can be detected by the control unit 5 to reduce the risk of further failures resulting from the component failure. During reduced speed / power operation, the lubricant pressure supplied to the turbocharger 10 can also be reduced to minimize or prevent lubricant leakage into the turbocharger 10 due to the reduced turbo boost pressure.

[0039] In some embodiments, the component fault mode can be determined based on whether the turbocharger boost pressure falls below a second boost pressure threshold and the control unit 5 of the internal combustion engine 1 detects a fault with a component of the internal combustion engine 1. By using additional sensor measurements, the control unit 5 can reduce the occurrence of false positives. As will be clear to those skilled in the field, the control unit 5 of the internal combustion engine 1 can be designed to monitor a variety of parameters of the internal combustion engine 1 during operation. For example, the control unit 5 can be designed to receive data indicating one or more of the following: crankcase pressure, temperature of the internal combustion engine 1, a vibration sensor connected to the internal combustion engine, a sensor connected to an aftertreatment system of the internal combustion engine 1, and the like.

[0040] Accordingly, the controller 5 can detect a component fault mode, which causes the internal combustion engine 1 to operate in a mode with reduced power output / reduced engine speed. To reflect this operating mode, the controller 5 can also reduce the lubricant pressure to the maximum leakage prevention pressure in order to reduce or prevent lubricant leakage.

[0041] In some embodiments where the controller 5 determines whether the internal combustion engine 1 is operating in a low-demand mode, the controller 5 also determines whether the internal combustion engine 1 is operating in an extended low-demand mode. In the extended low-demand mode, the turbocharger boost pressure can remain below a third boost pressure threshold for a period exceeding a time threshold. The extended low-demand mode, as such, can indicate that the turbocharger 10 operates at low boost pressure for an extended period, potentially leading to lubricant leakage. To counteract this, the controller 5, in the extended low-demand mode, can be configured to limit the electrical power supplied to the electric lubricant pump 4, ensuring that the lubricant pressure does not exceed an idle-speed pressure that is lower than the predetermined pressure.Therefore, in the extended low-demand operating mode, the lubricant pressure can be reduced compared to the predetermined pressure of the normal operating mode.

[0042] In some embodiments, determining whether the internal combustion engine is operating in the extended low-demand operating mode includes determining whether the turbocharger boost pressure is below the third boost pressure threshold and whether the engine speed of the internal combustion engine 1 is below a low-speed threshold for a period of time greater than the time threshold. For example, a low-speed threshold of an internal combustion engine 1 may be no more than approximately 110% or no more than approximately 105% of an idle speed of the internal combustion engine 1. For example, the time threshold may be at least 1 minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, or 1 hour. Therefore, if the internal combustion engine 1 is operating in the extended low-demand operating mode for a longer period of time, e.g.,When operating at idle speed, the lubricant pressure supplied to the turbocharger 10 (relative to the predetermined lubricant pressure of the normal operating mode) is reduced to reduce or prevent lubricant leakage.

[0043] In some embodiments, the controller 5 can determine that the internal combustion engine is operating in low-demand mode when the turbocharger boost pressure is below the third boost pressure threshold. The controller can then distinguish between extended low-demand mode, component failure mode, and turbocharger boost pressure-based failure mode. For example, in some embodiments, the third boost pressure threshold may be higher than the second boost pressure threshold, and the second boost pressure threshold may be higher than the first boost pressure threshold. Therefore, if the turbocharger boost pressure is between the second and third boost pressure thresholds, the internal combustion engine 1 can operate in extended low-demand mode. If the turbocharger boost pressure is between the first and second boost pressure thresholds, the internal combustion engine 1 can operate in component failure mode.If the turbo boost pressure falls below the first boost pressure threshold, the combustion engine 1 can operate in fault mode. In such an embodiment, the control unit 5 can distinguish between the three sub-modes. In other embodiments, the control unit 5 can distinguish between only two of the sub-modes, or the low-demand operating mode can be based on only one of the sub-modes.

[0044] Fig. Figure 4 presents a diagram of the relationship between lubricant pressure and engine speed of the internal combustion engine 1 for the normal operating mode and the extended low-demand operating mode according to this disclosure. For the internal combustion engine 1 of Fig.4. The idle speed of the internal combustion engine 1 can be approximately 1200 rpm. It is understood that below an idle speed of the internal combustion engine 1, the turbocharger 10 cannot be operational, and therefore the method according to this disclosure cannot be selectively implemented. That is, the methods according to this disclosure can only be implemented while the internal combustion engine 1 is operating at an engine speed of at least an idle speed. Commercial applicability

[0045] According to this disclosure, a method for controlling an internal combustion engine, a control system for an internal combustion engine 1, an internal combustion engine 1, and a machine are provided. The machine can be a generator or a work vehicle such as an excavator, a wheel loader, a bulldozer, a telescopic handler, a tractor, or the like.

[0046] The internal combustion engine 1 comprises a turbocharger 10, which is supplied with lubricant by an electric lubricant pump 4. According to embodiments of this disclosure, lubricant can be supplied to the turbocharger 10 at a predetermined lubricant pressure during normal operation of the internal combustion engine 1. During a low-demand operating mode (which may be a turbocharger failure mode, a component failure mode, or an extended low-demand operating mode) of the internal combustion engine 1, the lubricant pressure can be reduced to a leakage prevention pressure that is lower than the predetermined lubricant pressure in order to reduce or prevent the leakage of lubricant into the compressor and / or turbine of the turbocharger.

[0047] Such control of the lubricant pressure is possible because the lubricant is pressurized using an electric lubricant pump, the pumping power of which can be controlled independently of the operation of the internal combustion engine 1.

Claims

[1] A method for controlling an internal combustion engine comprising an electric lubricant pump and a turbocharger, comprising: Determine whether the internal combustion engine is operating in a normal operating mode in which a turbo boost pressure of the turbocharger is above a boost pressure threshold, or in a low-demand operating mode in which the turbo boost pressure is not above the boost pressure threshold, wherein, when it is determined that the internal combustion engine is operating in the normal operating mode, the method comprises supplying electrical power to the electric lubricant pump to cause lubricant to be supplied to the turbocharger at a pressure of at least a predetermined lubricant pressure; and wherein, when it is determined that the internal combustion engine is operating in the low demand operating mode, the method comprises reducing the electrical power supplied to the electric lubricant pump to lower the lubricant pressure to a leak prevention pressure that is lower than the predetermined lubricant pressure. [2] The method of claim 1, wherein, when operating in the normal operating mode, electrical power is supplied to the electric lubricant pump to cause lubricant to be supplied to the internal combustion engine at a pressure of at least a predetermined lubricant pressure, the predetermined lubricant pressure being controlled based on an engine speed of the internal combustion engine. [3] A method according to claim 1 or claim 2, wherein, when operating in the low demand mode of operation, electrical power is supplied to the electric lubricant pump to cause lubricant to be supplied to the internal combustion engine at the leak prevention pressure, the leak prevention pressure being controlled based on the engine speed of the internal combustion engine. [4] The method of any one of claims 1 to 3, wherein determining whether the internal combustion engine is operating in a low demand operating mode comprises: Determining whether the turbocharger is operating in a failure mode when the turbo boost pressure is below a first boost pressure threshold; wherein, if the turbocharger is determined to be operating in a failure mode, the method further comprises reducing the lubricant pressure to a leak prevention pressure that is lower than the leak prevention pressure. [5] The method of claim 4, wherein determining whether the turbocharger is operating in a failure mode comprises determining whether the turbo boost pressure is below a first boost pressure threshold and determining whether a turbo speed of the turbocharger is below an operating speed threshold. [6] A method according to claim 4 or claim 5, wherein when the turbocharger is determined to be operating in a failure mode, the method further comprises closing a turbo lubricant valve configured to control the supply of lubricant to the turbocharger to prevent the supply of lubricant to the turbocharger. [7] The method of any one of claims 1 to 6, wherein determining whether the internal combustion engine is operating in a low demand operating mode comprises: Determine whether the internal combustion engine is operating in a component failure mode based on whether the turbo boost pressure is below a second boost pressure threshold, wherein, if the internal combustion engine is determined to be operating in a component failure mode, the method further comprises: Limiting the engine speed of the internal combustion engine to no more than a first speed threshold and / or limiting the power output of the internal combustion engine to no more than a first power output threshold; and limiting the electrical power supplied to the electric lubricant pump such that the lubricant pressure is no greater than the leakage prevention pressure. [8] The method of claim 7, wherein determining whether the internal combustion engine is operating in the component failure mode comprises determining whether the turbo boost pressure is below a second boost pressure threshold and a controller of the internal combustion engine detects a fault in a component of the internal combustion engine. [9] The method of any one of claims 1 to 8, wherein determining whether the internal combustion engine is operating in a low demand operating mode comprises: Determining whether the internal combustion engine is operating in an extended low demand operating mode when the turbo boost pressure is below a third boost pressure threshold for a period of time greater than a time threshold, wherein, if the internal combustion engine is determined to be operating in an extended low demand operating mode, the method further comprises: Limiting the electrical power supplied to the electric lubricant pump so that the lubricant pressure is not higher than an idle speed pressure lower than the predetermined pressure. [10] The method of claim 9, wherein determining whether the engine is operating in an enhanced low demand operating mode comprises determining whether the turbo boost pressure is below the third boost pressure threshold and a controller of the engine determines that an engine speed of the engine is below a low speed threshold for a period of time greater than the time threshold. [11] A method according to claim 9 or 10 when dependent at least on claims 4 and 7, wherein the third boost pressure threshold is greater than the second boost pressure threshold, and the second boost pressure threshold is greater than the first boost pressure threshold. [12] A method according to any one of claims 1 to 11, wherein the predetermined lubricant pressure is at least 200 kPa. [13] A method according to any one of claims 1 to 12, wherein the leakage prevention pressure is not more than 80% of the predetermined lubricant pressure. [14] A control system for an internal combustion engine comprising an electric lubricant pump and a turbocharger, the control system being designed to: Determine whether the internal combustion engine is operating in a normal operating mode, where the turbocharger boost pressure is above a boost pressure threshold, or in a low demand operating mode, where the turbocharger boost pressure is not greater than the boost pressure threshold; wherein, when the controller determines that the internal combustion engine is operating in the normal operating mode, the controller is configured to cause electrical power to be supplied to the electric lubricant pump to cause lubricant to be supplied to the turbocharger at a pressure of at least a predetermined lubricant pressure; and when the controller determines that the internal combustion engine is operating in the low-demand operating mode, the controller is configured to reduce the electrical power supplied to the electric lubricant pump to reduce the lubricant pressure to a leakage prevention pressure lower than the predetermined lubricant pressure. [15] The controller of claim 14, wherein when the controller is configured to determine whether the internal combustion engine is operating in a low demand operating mode, the controller is configured to: Determining whether the turbocharger is operating in a failure mode when the turbo boost pressure is below a first boost pressure threshold; wherein, when the controller determines the turbocharger to be operating in a failure mode, the controller is configured to reduce the lubricant pressure to a failure leak prevention pressure that is lower than the leak prevention pressure. [16] The controller of claim 15, wherein when the controller determines the turbocharger to be operating in the fault mode, the controller is configured to cause a turbo lubricant valve of the internal combustion engine to close to prevent the supply of lubricant to the turbocharger. [17] A controller according to any one of claims 14 to 16, wherein when the controller is configured to determine whether the internal combustion engine is operating in a low demand operating mode, the controller is configured to: Determine whether the internal combustion engine is operating in a component failure mode based on whether the turbo boost pressure is below a second boost pressure threshold, wherein, when the controller determines the internal combustion engine to be operating in the component failure mode, the controller is configured to: Causing an engine speed of the internal combustion engine to be limited to no more than a first speed threshold and / or causing a power output of the internal combustion engine to be limited to no more than a first power output threshold; and Limiting the electric power supplied to the electric lubricant pump so that the lubricant pressure is not greater than the leakage prevention pressure. [18] A controller according to any one of claims 14 to 17, wherein when the controller is configured to determine whether the internal combustion engine is operating in a low demand operating mode, the controller is configured to: Determining whether the internal combustion engine is operating in an extended low demand operating mode when the turbo boost pressure is below a third boost pressure threshold for a period of time greater than a time threshold, wherein, when the controller determines the internal combustion engine to be operating in the extended low demand operating mode, the controller is configured to: Causing the electric power supplied to the electric lubricant pump to be limited so that the lubricant pressure is not greater than an idle speed pressure lower than the predetermined pressure. [19] A controller according to claim 18 when dependent on at least claims 15 and 17, wherein the third boost pressure threshold is greater than the second boost pressure threshold, and the second boost pressure threshold is greater than the first boost pressure threshold. [20] Internal combustion engine for a machine, the internal combustion engine comprising: a controller according to one of claims 14 to 19; a turbocharger; and an electric lubricant pump designed to supply lubricant to the turbocharger.

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