Method of starting an internal combustion engine

Abstract

A method of starting an internal combustion engine 1 comprising an electric lubricant pump 4, comprising performing an internal combustion engine cranking routine (101, Fig. 2) which causes a speed of the internal combustion engine to increase from rest to an idle speed, and concurrently with the internal combustion engine cranking routine, performing an electric lubricant pump start routine (102, Fig. 2); The electric lubricant pump start routine comprises supplying electrical power to the electric lubricant pump to cause a lubricant pressure of lubricant supplied to the internal combustion engine 1 to increase to a predetermined lubricant pressure; The electrical power supplied to the electric lubricant pump is controlled based on a rate of increase of the speed of the internal combustion engine from rest to the engine idle speed; the predetermined lubricant pressure may be selected based on a lubrication pressure of a turbocharger 10.

Description

Field of the disclosure The present disclosure relates to turbochargers. In particular, the present disclosure relates to lubrication of a turbocharger. Background Turbochargers typically comprise a compressor and a turbine. The compressor may be connected to the turbine by a bearing section comprising a bearing. Turbochargers bearings may be supplied with a continuous supply of lubricant (e.g. oil) to bearing surfaces to maintain shaft stability and prevent excessive wear of the bearing surfaces. In order to provide suitable lubrication, the lubricant may be supplied to the bearing section under pressure. If the turbocharger bearing is operated without sufficient lubricant pressure, the bearing surfaces may become worn and / or the bearing may seize. Low lubricant pressure is particularly prevalent during start-up of an internal combustion engine, as lubricant pressure may lower whilst the internal combustion engine is at rest. Lubricant flow may be supplied by a pump connected to an internal combustion engine. Conventionally, the pump is driven by the internal combustion engine. So, at start-up of the internal combustion engine, the change in pump speed, and thus the change in lubricant pressure, depends on the manner in which the internal combustion engine is started. In some known systems, the speed of the internal combustion engine may be held at a fixed idle speed for a period of time to allow the lubricant pressure to reach a sufficient level before allowing the internal combustion engine and associated components to operate at higher loads. Summary According to a first aspect of the disclosure a method of starting an internal combustion engine comprising an electric lubricant pump is provided. The method comprises performing an internal combustion engine cranking routine which causes a speed of the internal combustion engine to increase from rest to an idle speed, and concurrently with the internal combustion engine cranking routine, performing an electric lubricant pump start routine. The electric lubricant pump start routine comprises supplying electrical power to the electric lubricant pump to cause a lubricant pressure of lubricant supplied to the internal combustion engine to increase to a predetermined lubricant pressure. The electrical power supplied to the electric lubricant pump is controlled based on a rate of increase of the speed of the internal combustion engine from rest to the engine idle speed. The method of the first aspect utilises an electric lubricant pump to pressurise the lubricant supplied to the internal combustion engine upon starting the internal combustion engine. By utilising an electric lubricant pump, the power output of the electric lubricant pump may be varied independently of the power output of the internal combustion engine and its speed. That is to say, the power output of the electric lubricant pump is not dependent on, or limited by, the time taken for the internal combustion engine to start up. Thus, according to the method of the first aspect, the electrical power supplied to electric lubricant pump may be controlled in order to affect the rate at which the lubricant pressure increases up to a predetermined lubricant pressure. The predetermined lubricant pressure may be a lubricant pressure which provides for sufficient lubrication of the various components of the internal combustion engine during normal use. According to the first aspect, the rate at which the predetermined lubricant pressure is reached is based on the rate of increase of the speed of the internal combustion engine. As such, where the internal combustion engine is reaching an idle speed relatively quickly, the rate of increase of lubricant pressure may be increased to avoid an excessive delay once the internal combustion engine reaches the idle speed. Similarly, where the internal combustion engine reaches the idle speed slowly, for example due to a relatively low ambient temperature, the required rate of change may be adjusted accordingly. The method of the first aspect provides allows an internal combustion engine to be operated following a cold start relatively quickly. In particular, once the internal combustion engine reaches an idle speed, a delay to allow the lubricant pressure to reach a suitable pressure may be reduced or eliminated. In particular, the method according to the first aspect may allow a turbocharger to be sufficiently lubricated once the internal combustion engine reaches an idle speed, allowing the internal combustion engine to operate at higher loads and / or engine speeds without further delay. According to a second aspect of the disclosure, a controller for an internal combustion engine comprising an electric lubricant pump is provided. The controller is configured to cause the internal combustion engine to perform a start routine, wherein the controller is configured to cause the internal combustion engine to perform a cranking routine which causes a speed of the internal combustion engine to increase from rest to an idle speed. Concurrently with the internal combustion engine performing the cranking routine, the controller is configured to cause the electric lubricant pump to perform an electric lubricant pump start routine. The electric lubricant pump start routine comprises the controller causing electrical power to be supplied to the electric lubricant pump to cause a lubricant pressure of lubricant supplied to the internal combustion engine to increase to a predetermined lubricant pressure, wherein the controller controls the electrical power supplied to the electric lubricant pump based on a rate of increase of the speed of the internal combustion engine from rest to the engine idle speed. As such, the controller of the second aspect may be configured to cause an internal combustion engine comprising an electric lubricant pump to perform the method of the first aspect. According to a third aspect of the disclosure, an internal combustion engine comprising an electric lubricant pump and a controller according to the second aspect is provided. In some embodiments, the internal combustion engine is provided as part of a machine. The machine may also comprise a turbocharger. In some embodiments, the electric lubricant pump may be configured to supply lubricant to the turbocharger, wherein the predetermined lubricant pressure is selected based on a lubrication pressure of the turbocharger. Brief description of the figures Embodiments of the disclosure will now be described with reference to the following figures in which: Fig. 1 is a block diagram of an internal combustion engine and a turbocharger according to an embodiment of the disclosure; Fig. 2 is a block diagram of a method of starting an internal combustion engine according to an embodiment of the disclosure; Fig. 3 is a graph showing the change in lubricant pressure during a method of starting an internal combustion engine according to this disclosure; Fig. 4 is a graph showing the change in electrical power supplied to an electric lubricant pump during a method of starting an internal combustion engine; and Fig. 5 is a graph showing the relationship between the electrical power supplied to an electric lubricant pump and each of engine speed and lubricant temperature during a method of starting an internal combustion engine according to this disclosure. Detailed description According to an embodiment of the disclosure, an internal combustion engine 1 and a turbocharger 10 are provided. Fig. 1 shows a schematic system diagram of the internal combustion engine 1 and the turbocharger 10. The internal combustion engine 1 and turbocharger may be provided as part of a machine (not shown in Fig. 1). For example the machine may be a generator or a work vehicle such as an excavator, a wheel loader, a dozer, a telehandler, a tractor and the like. As shown in Fig. 1, the turbocharger 10 comprises a compressor 20, a bearing section 30, and a turbine 40. As shown in the system diagram of Fig. 1, the compressor 20 of the turbocharger 10 may be configured to receive an intake gas, for example from an air inlet (not shown in Fig. 1). The compressor 20 of the turbocharger 10 may output the compressed intake gas directly to the internal combustion engine 1, or via an aftercooler (not shown in Fig. 1). The turbine 40 of the turbocharger 10 may be configured to receive gas from the internal combustion engine 1. The flow of various gasses to and from the internal combustion engine 1 and turbocharger 10 are indicated in Fig. 1 using dashed lines. The bearing section 30 comprises a bearing 32 which 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 associated surfaces which of the bearing section 30 / turbocharger 10, the bearing section 30 of the turbocharger 10 may be provided with a supply of lubricant. In reduce or prevent wear of the bearing 32, the bearing section 30 may be supplied with lubricant at a lubricant pressure which is at least a first lubricant pressure. If the turbocharger 10 is operated when the lubricant pressure is below the first lubricant pressure, the bearing 32 may not be sufficiently lubricated. Prolonged operation of the turbocharger 10 when the lubricant pressure is below the first lubricant pressure may reduce the operational lifetime of the turbocharger 10. As shown in the system diagram of Fig. 1, the internal combustion engine 1 comprises a lubricant reservoir 3 and an electric lubricant pump 4. The electric lubricant pump 4 is fluidly connected to the lubricant reservoir 4 and the bearing section 30 of the turbocharger 10. The electric lubricant pump 4 is configured to pump lubricant from the lubricant reservoir 3 to the bearing section 30 in order to lubricate the bearing 32. The bearing section 32 is also fluidly connected to 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 has been operational for at least several minutes), the electric lubricant pump 4 may pump lubricant from the lubricant reservoir 3 to the turbocharger 10. Lubricant may circulate through the bearing section 30 of the turbocharger 10 and return to the lubricant reservoir 3 via the return path 6 shown schematically in Fig. 1. According to this disclosure, an electric lubricant pump 4 is understood to be a pump which may be powered by electrical energy in order to pump lubricant. For example, in some embodiments, the electric lubricant pump 4 may comprise an electric motor (not shown), the electric motor configured to receive electrical energy (e.g. from a battery connected to the motor, for example a battery of the internal combustion engine 1) and to pump lubricant at a predetermined lubricant pressure. As such, it will be appreciated that the electric lubricant pump 4 may not be powered directly by mechanical energy generated by the internal combustion engine. In particular, the power output of the electric lubricant pump 4 may not be dependent on the engine speed of the internal combustion engine 1. The electric lubricant pump 4 may be configured to pump lubricant to bearing section 30. In normal operation, the electric lubricant pump may be configured to supply lubricant to the bearing section 30 at a predetermined lubricant pressure. The predetermined lubricant pressure may be selected to ensure that lubricant is provided to the bearing section 30 at a sufficient pressure in order to lubricate all relevant surfaces of the bearing section 30 and turbocharger 10. It is important to provide lubricant at a sufficient pressure to reduce or prevent wear of the bearing 32 when the turbocharger is in use. As such, the predetermined lubricant pressure may be greater than or equal to the first lubricant pressure. For example, in some embodiments, the first lubricant pressure may be at least: 50 kPa, 60 kPa, 70 kPa, 80 kPa, 90 kPa or 100 kPa. In some embodiments, the predetermined lubricant pressure may be at least: 10%, 20 %, 50 %, or 100% greater than the first lubricant pressure in order to provide an operational margin. In some embodiments, the predetermined lubricant pressure may not exceed the first lubricant pressure by more than e.g. 500 %, or 400 % of the first lubricant pressure. In some embodiments, it may be desirable to supply lubricant to the turbocharger 10 at a pressure which does not significantly exceed the pressure required for lubrication of the turbocharger 10 in order to operate the internal combustion engine 1 and electric lubricant pump 4 in an efficient manner. In embodiments where the electric lubricant pump 4 is configured to supply lubricant to other components associated with the internal combustion engine 1 (either in addition to, or as an alternative to turbocharger 10), the predetermined lubricant pressure may be selected based on the lubricant pressures which provide sufficient lubrication of said other components. As such, it will be appreciated that the predetermined lubrication pressure may be a lubricant pressure which is suitable for providing sufficient lubrication of the components which are fluidly connected to the electric lubricant pump 4. It will be appreciated that when the internal combustion engine is at rest (i.e. engine speed is 0 revolutions per minute (rpm)), the lubricant pressure of lubricant in the bearing section 30 (or any other part of the lubrication system of the internal combustion engine 1) may fall below the predetermined lubricant pressure. For example, upon starting an internal combustion engine, the lubricant pressure may be at a rest pressure which may be significantly below the predetermined lubricant pressure, e.g. 0 Pa. In order to prevent or reduce wear of the bearing section 30 of the turbocharger 10, it may be desirable to ensure that the lubricant supplied to the turbocharger is at the predetermined lubricant pressure before the turbocharger 10 is operated. As the power output of the electric lubricant pump 4 is not dependent on the power output of the internal combustion engine 1, the electric lubricant pump 4 may be controlled during start-up of the internal combustion engine to ensure that the predetermined lubricant pressure is provided as part of a method 100 of starting an internal combustion engine 1 according to this disclosure. The method 100 of starting the internal combustion engine 1 may be performed by the internal combustion engine 1 of Fig. 1. As shown in Fig. 1, the internal combustion engine 1 may be controlled by a controller 5 of the internal combustion engine 1. For example, the controller 5 may be an Engine Control Unit (ECU) or any other suitable computer or microprocessor which is suitable for controlling the internal combustion engine 1. Fig. 2 shows a block diagram of a method 100 of starting an internal combustion engine 1 comprising an electric lubricant pump 4 according to this disclosure. While the method 100 discussed herein is configured to provide a predetermined lubricant pressure which is suitable for operation of turbocharger 10, it will be appreciated that the method 100 is not limited to supplying lubricant to a turbocharger. That is to say, method 100 may be suitable for starting an internal combustion engine 1 whilst arriving at a suitable (predetermined) lubricant pressure for any components of the internal combustion engine 1 and / or any other component requiring lubrication associated with the internal combustion engine 1. Method 100 may be initiated (START) when the controller 5 receives a signal indicating that the internal combustion engine is to be started. For example, the controller 5 may be configured to receive a “KEY ON” signal from a user interface connected to the controller 5. As shown in Fig. 2, the method 100 comprises a step 101 of performing an internal combustion engine cranking routine. The internal combustion engine cranking routine causes a speed (rpm) of the internal combustion engine 1 to increase from rest (i.e. 0 rpm) to an idle speed. By idle speed, it is understood that the idle speed is an engine speed which is sufficient to sustain the internal combustion engine’s operation under its own power. For example, the idle speed of the internal combustion engine 1 may be about 1300 rpm. In order to reach the idle speed, an external power source (not shown) may be applied to rotate (crank) the internal combustion engine 1. For example, an external power source suitable for cranking an internal combustion engine 1 may be one or more of: a starter motor, a pneumatic starter, a hydraulic motor for example. The external power source used to crank the engine may be selected in accordance with the size and intended use for the internal combustion engine 1. The time taken to perform the internal combustion engine cranking routine 101 may not be a consistent time period. That is to say, the time taken to perform the internal combustion engine cranking routine 101 may depend on environmental factors such as ambient temperature, the temperature of the internal combustion engine 1, the fuel temperature and the like. The time taken may also depend on the size and type of internal combustion engine, as will be appreciated by the skilled person. For example, at ambient temperature (e.g. 25 °C), a typical duration of an internal combustion engine cranking routine may be in the range of about 3 to 5 seconds. At a lower temperature (e.g. about 0 °C), a typical duration of an internal combustion engine cranking routine 102 for the same internal combustion engine 1 may be in the range of about 10 to 15 seconds. That is to say, the duration of the internal combustion engine cranking routine 101 may vary, relative to the average time taken at ambient temperature, by at least: 100%, 150% or 200% of the average duration, based on e.g. environmental factors. During the internal combustion engine cranking routine, the turbocharger 10 may not be operated. For example, the power output of the internal combustion engine 1 may not be sufficient for beneficial operation of the turbocharger 10 during the internal combustion engine cranking routine 101. Furthermore, it may be desirable to avoid operation of the turbocharger 10 whilst the lubricant is not sufficiently pressurised to prevent or reduce wear of the turbocharger 10. Concurrently with the internal combustion engine cranking routine (step 101), the method 100 comprises a step of performing an electric lubricant pump start routine 102. The electric lubricant pump start routine 102 comprises supplying electrical power to the electric lubricant pump 4. Accordingly, the electric lubricant pump 4 is operated to pump (or pressurise) the lubricant supplied to the internal combustion engine 1 and associated components such as turbocharger 10. As such, the supply of electrical power to the electric lubricant pump 4 causes a lubricant pressure output by the pump to increase gradually. The electric lubricant pump start routine 102 may be controlled by the controller 5 to cause the lubricant pressure supplied to the internal combustion engine 1 to increase to a predetermined lubricant pressure. As discussed above, in the embodiment of Fig. 1, the predetermined lubricant pressure may be selected based to be at least the first lubricant pressure for sufficiently lubricating the turbocharger 10. As the internal combustion engine 1 may have been at rest for some time, the lubricant pressure upon commencing the electric lubricant pump start routine 102 may be significantly below the predetermined lubricant pressure. As such, it will be appreciated that the electric lubricant pump 4 may not be capable of instantaneously pressurising the lubricant system to the predetermined lubricant pressure. Rather, a period of time may be required for the electric lubricant pump 4 to cause the lubricant pressure to reach the predetermined lubricant pressure. In order to efficiently operate the electric lubricant pump 4, it may be desirable to ensure that the lubricant pressure reaches the predetermined lubricant pressure shortly before the end of the internal combustion engine cranking routine 101. As such, according to the electric lubricant pump start routine, the controller 5 controls the electrical power supplied to the electric lubricant pump based on a rate of increase of the speed of the internal combustion engine from rest to the engine idle speed. For example, where the internal combustion engine 1 is reaching idle speed relatively slowly, a greater time period is available for pressurising the lubricant, and so the electrical power supplied to the pump may be reduced in order to operate the electric lubricant pump 4 in an efficient manner. Where the internal combustion engine 1 is reaching idle at a faster rate, the power supplied to the electrical lubricant pump 4 may be increased in order to ensure that the predetermined lubricant pressure is reached before the end of the internal combustion engine cranking routine. For example in some embodiments, the electrical power supplied to the electric lubricant pump 4 may be controlled to increase at a rate based on the rate of increase of the speed of the internal combustion engine 1. For example, at the start of the electric lubricant pump start routine, the power may increase from a rest power (e.g. zero power) at a rate which is based on the rate of increase of the speed of the internal combustion engine 1. In some embodiments, it will be appreciated that the rate of change of the lubricant pressure depends, at least in part, on the temperature of the lubricant. The temperature of the lubricant may be influenced by one or more of: the ambient temperature, the internal combustion engine temperature, and the operational history of the internal combustion engine. In particular, a viscosity of the lubricant may depend on the temperature of the lubricant, with a lower temperature causing the viscosity of the lubricant to increase. The viscosity of the lubricant may in turn affect rate at which the lubricant pressure increases when the electric lubricant pump 4 is operated. As such, for a given electrical power supplied to the electric lubricant pump 4, the time taken to reach the predetermined lubricant pressure may increase as the (initial) lubricant temperature is lowered. Thus, in some embodiments, the controller may control the rate of increase of the electrical power supplied to the electric lubricant pump 4 based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed and a temperature indicative of a temperature of the lubricant. In some embodiments, the controller 5 may determine a temperature of the lubricant based on the output of one or more temperature sensors associated with the internal combustion engine 1. For the purpose of the method of starting the internal combustion engine 1, the controller 5 may determine a temperature of the lubricant based on a temperature determined at the start of the method 100. For example, the controller 5 of the internal combustion engine 1 may be configured to receive a signal indicative of a temperature of the lubricant from an air inlet temperature sensor, a lubricant temperature sensor, a coolant temperature sensor, or an ambient temperature sensor of the internal combustion engine 1 (all not shown in Fig. 1). As such, the temperature indicative of a temperature of the lubricant may be determined by the controller 5 based on one or more of: an air inlet temperature, a lubricant temperature, a coolant temperature, and an ambient temperature produced by a respective sensor. Where one or more temperature readings are available to the controller 5, the controller 5 may determine the temperature of the lubricant as an average of the available temperature readings for example. Fig. 3 is a graph showing how lubricant pressure varies with time as part of a method 100 of staring an internal combustion engine 1 according to this disclosure. Fig. 3 shows two graphs which illustrate the change in lubricant pressure. One graph shows the change based on a relative fast increase in engine speed and another graph shows the change based on a relatively slower increase in engine speed. In each case, the electric lubricant pump routine 102 causes the lubricant pressure to reach the predetermined lubricant pressure before the speed of the internal combustion engine reaches the idle speed. As shown in Fig. 3, the time taken for the internal combustion engine 1 to reach the idle speed varies. By utilising an electric lubricant pump 4, the method 100 ensures that the internal combustion engine 1 and associated components (e.g. turbocharger 10) are sufficiently lubricated such that they are ready to be operated at the end of the internal combustion engine cranking routine 101. As such, the method 100 may reduce or eliminate any holding period where the internal combustion engine 1 is maintained in an idle state to wait for the lubricant pressure to increase. In some embodiments, the controller 5 may cause the lubricant pressure to reach the predetermined lubricant pressure at the end of the internal combustion engine start routine 101. For example, the controller 5 may predict an expected duration for the internal combustion engine start routine 1 based on the rate of change in engine speed, and adjust the electrical power supplied to the electric lubricant pump 4 accordingly. In some embodiments, the controller 5 may cause the lubricant pressure to reach the predetermined lubricant pressure before the predicted end of the internal combustion engine start routine 101. For example, the controller may control the electric lubricant pump 4 to reach that predetermined pressure over a duration which is no greater than 95 %, 90 %, 85 %, or 80 % of the predicted duration of the internal combustion engine start routine 101. As such, the controller 5 may include a margin of at least 5 % to improve the resilience of the method 100. In some embodiments, the internal combustion engine 1 may comprise a lubricant pressure sensor which is configured to detect a current lubricant pressure which is indicative of the lubricant pressure output by the electric lubricant pump 4. The controller 5 may utilise the lubricant pressure sensor to control the electrical power supplied to the electric lubricant pump 4. As such, in some embodiments, the rate of increase of the electrical power supplied to the electric lubricant pump may be controlled based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed, the predetermined lubricant pressure, and a current lubricant pressure. As such, the lubricant pressure sensor may provide feedback to the controller 5 and electric lubricant pump 4 to further improve the resilience of the electric lubricant pump start routine 102. Fig. 4 is a further graph showing the change in electrical power supplied to the electric lubricant pump over the duration of the electric lubricant pump start routine 102. The graph of Fig. 4 shows the variation in electrical power for the example shown in Fig. 3. As shown in Fig. 3, the electrical power supplied to the electric lubricant pump 4 increases from a rest power to a first power over the duration of the electric lubricant pump start routine. The first power may be selected based on a rate of increase of the speed of the internal combustion engine. As such, where the engine speed is increasing at a faster rate, the time taken for the internal combustion engine 1 to reach idle speed may be reduced. Accordingly, in order to supply sufficient energy to bring the lubricant up to the predetermined lubricant pressure, the first power may be increased. Where the engine speed is increasing at a slower rate, the time taken for the internal combustion engine 1 to reach idle speed may be increased. With a longer time period to pressurise the lubricant, the first power may be reduced in order to operate the electric lubricant in a more efficient manner. As shown in the embodiment of Figs. 3 and 4, the electrical power supplied to the electric lubricant pump increases linearly over the duration of the electric lubricant pump start routine. In other embodiments, a different relationship may be used, for example, a polynomial relationship and the like. Once the internal combustion engine 1 reaches the idle speed at the end of the internal combustion engine start routine 101, the method of starting the internal combustion engine 1 may end. According to method 100, as the internal combustion engine 1 reaches the idle speed, the lubricant pressure is at the predetermined lubricant pressure, and so the internal combustion engine 1 and any associated components may be operated in a normal manner. As shown in Fig. 4, once the internal combustion engine 1 reaches idle speed, the electric lubricant pump 4 is supplied with a second power. The second power may be an amount of power required to maintain the predetermined lubricant pressure once the lubrication system is sufficiently pressurised. As will be appreciated from Fig. 4, in some embodiments where the internal combustion engine 1 reaches the idle speed relatively quickly, the electric lubricant pump 4 may be supplied with a first power which is greater than the second power required for normal operation. In some embodiments, controller 5 may select a rate of increase of the electrical power supplied to the electric lubricant pump 4 based on the initial conditions of the internal combustion engine. In some embodiments, the controller 5 may update the rate of increase of the electrical power supplied to the electric lubricant pump over the duration of the electric lubricant pump start routine. As such, during the electric lubricant pump start routine 102, the electrical power supplied may be controlled based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed and a current speed of the internal combustion engine. Fig. 4 shows that the first power to be reached by the electric lubricant pump 4 may be varied based on the rate of change of the engine idle speed. In some embodiments, the first power may also vary based on the temperature of the lubricant. Lubricant at a lower temperature may be more viscous, and therefore require more energy to bring up to the predetermined lubricant pressure. Thus, in some embodiments, the first power may be selected by the controller 5 based on the temperature of the lubricant and the rate of change of the engine idle speed. Fig. 5 is a graph summarising the relationship between the electrical power supplied to the electric lubricant pump and each of the lubricant temperature and the rate of increase of the speed of the internal combustion engine. Industrial applicability According to this disclosure, a method of starting an internal combustion engine 1 is provided. The internal combustion engine 1 may be a diesel engine, a petrol engine, or an internal combustion engine configured to run on an alternative fuel such as hydrogen, acetylene, natural gas, liquefied petroleum gas, ethanol, and biofuel. In some embodiments, the internal combustion engine 1 may be associated with a turbocharger 10 and / or other components which utilise a supply of lubricant provided from the internal combustion engine 1. The internal combustion engine 1 according to this disclosure is provided with an electric lubricant pump 4 which is controlled to enable sufficient lubrication for the internal combustion engine 1 and the associated components at the end of the start routine. The internal combustion engine 1 and turbocharger may be provided as part of a machine. For example the machine may be a generator or a work vehicle such as an excavator, a wheel loader, a dozer, a telehandler, a tractor and the like. Embodiments of this disclosure utilise an electric lubricant pump 4 to pressurise the lubricant supplied to the internal combustion engine 1 upon starting the internal combustion engine 1. By utilising an electric lubricant pump 4, the power output of the electric lubricant pump 4 may be varied independently of the power output of the internal combustion engine 1. That is to say, the power output of the electric lubricant pump 4 is not dependent on, or limited by, the time taken for the internal combustion engine 1 to start up. This enables the electric lubricant pump 4 to bring the lubricant pressure up to the predetermined lubricant pressure concurrently with the cranking of the internal combustion engine 1. Thus, embodiments of this disclosure allow an internal combustion engine 1 to be started and become operational in a shorter period of time.

Claims

1. A method of starting an internal combustion engine comprising an electric lubricant pump, the method comprising:performing an internal combustion engine cranking routine which causes a speed of the internal combustion engine to increase from rest to an idle speed; andconcurrently with the internal combustion engine cranking routine, performing an electric lubricant pump start routine comprising:supplying electrical power to the electric lubricant pump to cause a lubricant pressure of lubricant supplied to the internal combustion engine to increase to a predetermined lubricant pressure,wherein the electrical power supplied to the electric lubricant pump is controlled based on a rate of increase of the speed of the internal combustion engine from rest to the engine idle speed.

2. A method according to claim 1, whereinthe electrical power supplied to the electric lubricant pump is controlled to increase at a rate based on the rate of increase of the speed of the internal combustion engine.

3. A method according to claim 2, whereinthe electrical power supplied to the electric lubricant pump increases from a rest power to a first power over the duration of the electric lubricant pump start routine.

4. A method according to claim 2 or claim 3, whereinthe electrical power supplied to the electric lubricant pump increases linearly.

5. A method according to any of claims 1 to 4, whereinthe rate of increase of the electrical power supplied to the electric lubricant pump is controlled based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed and a temperature indicative of a temperature of the lubricant.

6. A method according to claim 5, whereinthe temperature indicative of a temperature of the lubricant is based on one or more of: an air inlet temperature, a lubricant temperature, a coolant temperature, and an ambient temperature.

7. A method according to any of claims 1 to 6, whereinthe electric lubricant pump routine causes the lubricant pressure to reach the predetermined lubricant pressure before the speed of the internal combustion engine reaches the idle speed.

8. A method according to any of claims 1 to 7, whereinthe rate of increase of the electrical power supplied to the electric lubricant pump is controlled based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed and a current speed of the internal combustion engine.

9. A method according to any of claims 1 to 8, whereinthe rate of increase of the electrical power supplied to the electric lubricant pump is controlled based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed, the predetermined lubricant pressure, and a current lubricant pressure.

10. A method according to any of claims 1 to 9, whereinthe electric lubricant pump supplies lubricant to a turbocharger of the internal combustion engine, wherein the predetermined lubricant pressure is selected based on a lubrication pressure of the turbocharger.

11. A controller for an internal combustion engine comprising an electric lubricant pump, the controller configured to cause the internal combustion engine to perform a start routine, wherein the controller is configured to:cause the internal combustion engine to perform a cranking routine which causes a speed of the internal combustion engine to increase from rest to an idle speed; andconcurrently with the internal combustion engine performing the cranking routine, the controller is configured to cause the electric lubricant pump to perform an electric lubricant pump start routine comprising:the controller causing electrical power to be supplied to the electric lubricant pump to cause a lubricant pressure of lubricant supplied to the internal combustion engine to increase to a predetermined lubricant pressure,wherein the controller controls the electrical power supplied to the electric lubricant pump based on a rate of increase of the speed of the internal combustion engine from rest to the engine idle speed.

12. A controller according to claim 11, whereinthe controller causes the electrical power supplied to the electric lubricant pump to increase at a rate based on the rate of increase of the speed of the internal combustion engine.

13. A controller according to claim 12, whereinthe controller causes the electrical power supplied to the electric lubricant pump to increase from a rest power to a first power over the duration of the electric lubricant pump start routine.

14. A controller according to claim 12 or claim 13, whereinthe electrical power supplied to the electric lubricant pump increases linearly.

15. A controller according to any of claims 11 to 14, whereinthe controller is configured to control the rate of increase of the electrical power supplied to the electric lubricant pump based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed and a temperature indicative of a temperature of the lubricant.

16. A controller according to claim 15, whereinthe temperature indicative of a temperature of the lubricant is based on one or more of: an air inlet temperature, a lubricant temperature, a coolant temperature, and an ambient temperature received by the controller.

17. A controller according to any of claims 11 to 16, whereinthe electric lubricant pump routine causes the lubricant pressure to reach the predetermined lubricant pressure before the speed of the internal combustion engine reaches the idle speed.

18. A controller according to any of claims 11 to 17, whereinthe controller is configured to control the rate of increase of the electrical power supplied to the electric lubricant pump based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed and a current speed of the internal combustion engine.

19. A controller according to any of claims 11 to 18, whereinthe controller is configured to control the rate of increase of the electrical power supplied to the electric lubricant pump based on the rate of increase of the speed of the internal combustion engine from rest to the engine idle speed, the predetermined lubricant pressure, and a current lubricant pressure.

20. An internal combustion engine comprising:an electric lubricant pump; anda controller according to any of claims 11 to 19, wherein optionallythe internal combustion engine is associated with a turbocharger, wherein the electric lubricant pump is configured to supply lubricant to the turbocharger, and the predetermined lubricant pressure is selected based on a lubrication pressure of the turbocharger.19

Images