fixed speed engine

Abstract

A method of cranking a fixed speed engine (40) is provided, the method comprising the steps of: a) providing an engine start command; b) enabling one or more cylinders (42) of the fixed speed engine; and c) enabling a pilot injection mode during cranking of the engine, wherein in the pilot injection mode each cylinder cycle of the one or more enabled cylinders includes one or more pilot injections followed by a main injection.

Description

[0001] The present disclosure relates to fixed speed engines and methods of cranking a fixed speed engine and controlling a cylinder deactivation mode of the engine. BACKGROUND

[0002] Fixed speed engines are engines designed and configured to operate at one fixed speed or a limited number of fixed speeds. Fixed speed engines can be used, for example, to generate electricity as part of a primary power generation scheme or as part of a backup / standby power generation scheme. In one exemplary use, a fixed speed engine can be used to generate electricity in the event of a primary power failure.

[0003] Accordingly, some fixed speed engines can be used occasionally and infrequently, but must be reliable in order to satisfactorily serve as a backup / standby power generator. A primary requirement of a backup / standby power generator can be the ability to start reliably and quickly in the event of a primary power failure.

[0004] Additionally, fixed speed engines can be used in a variety of environmental conditions. For example, a fixed speed engine used as a backup / standby power generator can be located indoors or outdoors and can be required to operate in a variety of environmental conditions, including cold environmental conditions. SUMMARY

[0005] An embodiment of the present disclosure provides a method of cranking a fixed speed engine, the method comprising the steps of:

[0006] a) providing an engine start command;

[0007] b) enabling one or more cylinders of the fixed speed engine; and

[0008] c) enabling a pilot injection mode during cranking of the engine

[0009] wherein in the pilot injection mode, each cylinder cycle of the one or more enabled cylinders includes one or more pilot injections followed by a main injection.

[0010] Another embodiment of the present disclosure provides a fixed speed engine, the fixed speed engine comprising a plurality of cylinders and a controller configured to, during cranking of the engine:

[0011] enable one or more cylinders of the fixed speed engine; and

[0012] enable a pilot injection mode;

[0013] wherein in the pilot injection mode, each cylinder cycle of the one or more enabled cylinders includes one or more pilot injections followed by a main injection.

[0014] Another embodiment of the present disclosure provides a method of controlling a cylinder deactivation mode for a fixed speed engine, the method comprising the steps of:

[0015] a) enabling a cylinder deactivation mode wherein one or more cylinders of the engine are deactivated while one or more cylinders of the engine remain activated;

[0016] b) injecting a main injection and optionally one or more pilot injections into the one or more activated cylinders during each cylinder cycle while the cylinder deactivation mode remains active; and

[0017] c) injecting one or more pilot injections but not a main injection into the one or more deactivated cylinders during each cylinder cycle while the cylinder deactivation mode remains active.

[0018] Another embodiment of the present disclosure provides a fixed speed engine comprising a plurality of cylinders and a controller configured to:

[0019] a) enable a cylinder deactivation mode wherein one or more cylinders of the engine are deactivated while one or more cylinders of the engine remain activated;

[0020] b) inject a main injection and optionally one or more pilot injections into the one or more activated cylinders during each cylinder cycle while the cylinder deactivation mode remains active; and

[0021] c) inject one or more pilot injections but not a main injection into the one or more deactivated cylinders during each cylinder cycle while the cylinder deactivation mode remains active. BRIEF DESCRIPTION OF DRAWINGS

[0022] One or more embodiments of the present disclosure will now be described, by way of example only, with reference to the attached drawings in which:

[0023] Figure 1 is a schematic illustration of an engine and controller;

[0024] Figure 2 is a schematic representation of various cylinder layouts for an engine;

[0025] Figure 3 is a schematic flow chart of an embodiment of a cylinder deactivation mode;

[0026] Figure 4 is a plot of engine speed versus time for two engine configurations, A and B; and

[0027] Figure 5is a graph of total hydrocarbon count versus time for two engine configurations, A and B. DETAILED DESCRIPTION

[0028] Unless otherwise defined, all technical and scientific terms used in the present specification have the same meaning as commonly understood by one of ordinary skill in the art to which the claimed subject matter belongs. It should be understood that the foregoing summary of the disclosure and the following examples are merely exemplary and explanatory, and are not restrictive of any subject matter claimed.

[0029] The following description relates to embodiments of the present disclosure. The description of the embodiments is not meant to include all possible embodiments of the present disclosure claimed in the appended claims. Many modifications, improvements, and equivalents of the embodiments described in the following embodiments can fall within the scope of the appended claims. Features described as part of one embodiment can be combined with features of one or more other embodiments unless the context explicitly requires otherwise.

[0030] In this specification, the use of the singular includes the plural unless specifically stated otherwise. In this application, the use of "and / or" means "and" and "or" unless stated otherwise.

[0031] Figure 1 A schematic is shown for illustrating an engine 40 and a controller 41 of the present disclosure. The engine 40 can include a plurality of cylinders 42.

[0032] The engine 40 is a fixed speed engine. The engine 40 can form part of a generator, also known as a genset. The generator can be a stationary generator or a mobile generator. The generator can be an emergency generator. The generator can be used to generate electricity, or as part of a combined heat and power (CHP) generator, which combines electricity and useful heat.

[0033] Alternatively, the engine 40 can form part of a machine, or can be a standalone engine. The machine can include a mobile machine or a stationary machine. The machine can include a wheeled machine or a tracked machine. The machine can be used in the construction and / or mining industries. For example, the machine can include a tractor, a bulldozer, a pipelayer, an automatic grader, a wheel tractor scraper, an excavator, a backhoe loader, a track loader, a wheel loader, an articulated dump truck, a rigid dump truck, or a compactor. The machine can include a locomotive.

[0034] The engine 40 can be an internal combustion engine (ICE). The ICE can use diesel as its primary fuel. The diesel can be, for example, regular diesel or biodiesel.

[0035] Engine 40 can have a plurality of cylinders 42. Engine can have 2 or more cylinders 42, optionally 4 or more cylinders 42, optionally 6 or more cylinders 42, optionally 8 or more cylinders 42, optionally 12 or more cylinders 42, optionally 16 or more cylinders 42, optionally 24 or more cylinders 42.

[0036] Engine 40 can have a fixed speed of, for example, 1500 rpm to 1800 rpm. Fixed speed can be 1500 rpm. Fixed speed can be 1800 rpm. Engine 40 can have a single fixed speed, or can be configured to take on a limited number of fixed speeds. For example, engine 40 can switch between operating at 1500 rpm and operating at 1800 rpm.

[0037] Engine 40 can have a compression ratio of less than 14: 1.

[0038] Engine 40 can have a power density of greater than 20 bar gross BMEP, optionally greater than 28 bar gross BMEP, optionally greater than 30 bar gross BMEP.

[0039] Engine 40 can have a cylinder displacement of 3 liters or more per cylinder 42.

[0040] Engine 40 can have an engine displacement of 23 liters or more, optionally 23 liters to 61 liters.

[0041] Controller 41 can include hardware and / or software. Controller 41 can include a control unit, or can be a computer program running on a dedicated or shared computing resource. Controller 41 can include a single unit, or can be made up of a plurality of sub-units operatively connected. Controller 41 can be located on one processing resource, or can be distributed across spatially separated computing resources. Controller 41 can include one or more programmable and / or non-programmable memory units or sub-units. Controller 41 can include data storage and processing units or sub-units. Controller 41 can include or form part of an engine electronic control module (ECM) operatively connected to engine 40.

[0042] Controller 41 can utilize one or more variables associated with operation of engine 40. Variables can include one or more of engine speed 43, engine coolant temperature 44, engine intake manifold temperature 45, and engine load factor 46.

[0043] Engine 40 and / or controller 41 can include one or more associated sensors for detecting, determining, calculating, or inferring the above-mentioned variables. For example, one or more of an engine coolant temperature sensor, an engine intake manifold temperature sensor, an engine speed sensor, an engine manifold absolute pressure sensor, a throttle position sensor, and an intake air sensor can be provided.

[0044] A method of cranking a fixed speed engine 40 is provided. The method includes the steps of providing an engine start command, enabling one or more cylinders 42 of the engine 40, and enabling a pilot injection mode during cranking of the engine 40.

[0045] The fixed speed engine 40 can include a starter motor to assist in the enabling of the one or more cylinders 42 upon receipt of an engine start command.

[0046] In the pilot injection mode, each cylinder cycle of the one or more enabled cylinders includes one or more pilot injections followed by a main injection. The pilot injection mode can also be referred to as a “two-shot” mode because it includes at least two injections. The main injection mode (without any pilot injections) can also be referred to as a “one-shot” mode.

[0047] In this specification, the term “cranking” means a period after engine start during which the engine speed is ramped up to obtain its desired fixed speed.

[0048] In this specification, the term “deactivated”, “deactivating”, and derivatives thereof with respect to one or more cylinders 42 means that the one or more cylinders 42 are configured to receive at least one main injection per cycle of combustion to provide useful power. In contrast, one or more of the cylinders 42 can be “deactivated” or “switched off” so as to not receive a main injection per cycle of combustion to provide useful power. Deactivation / switching off of a cylinder can be achieved, for example, by keeping the intake and exhaust valves of a particular cylinder 42 closed or by disabling the fuel injectors of a particular cylinder 42.

[0049] Controller 41 can be configured to enable the pilot injection mode each time the engine 40 is cranked.

[0050] Alternatively, controller 41 can be configured to check one or more entry conditions to determine whether to enable the pilot injection mode during cranking of the engine 40. In some embodiments, controller 41 can be configured to determine whether the engine coolant temperature 44 is below a pilot mode threshold temperature. If yes, the pilot injection mode can be enabled during cranking; if no, the pilot injection mode can not be enabled during cranking. The pilot mode threshold temperature of the engine coolant temperature 44 can be, for example, 60°C.

[0051] The engine start instruction can be provided by actuation of a virtual or physical key, a switch, a button, or other actuator. In some embodiments, the engine start instruction is provided by a key used to operate the ignition controller. Start of the engine 40 can be under control of the controller 41.

[0052] In the pilot injection mode, the one or more pilot injections can be injected, for example, at 13° to 17°, optionally at 15°, BTDC. The one or more pilot injections can have, for example, a total volume per cycle per cylinder of 30 mm 3 to 200 mm 3 , optionally 30 mm 3 to 80 mm 3 , optionally 30 mm 3 to 75 mm 3 , optionally 35 mm 3 , optionally 75 mm 3 to 200 mm 3 , optionally 80 mm 3 to 200 mm 3 .

[0053] The one or more pilot injections can have, for example, a total volume per cycle per cylinder of 10% to 25% of the main injection volume.

[0054] In the pilot injection mode, the main injection can be injected, for example, at 3° to 7°, optionally at 5°, BTDC. The main injection can have, for example, a total volume per cycle per cylinder of 300 mm 3 to 800 mm 3 .

[0055] The pilot injection mode can remain active throughout the entire rotational start of the engine 40. Alternatively, once the engine 40 obtains a speed within 250 rpm of its fixed speed, optionally within 200 rpm of its fixed speed, optionally within 100 rpm of its fixed speed, the pilot injection mode can be deactivated and the main injection mode (e.g., single injection mode) can be initiated on the one or more enabled cylinders 42. For example, in the main injection mode, each enabled cylinder 42 can receive only a main injection, and no pilot injection, per cycle. Such a main injection can be injected, for example, at 15°, BTDC.

[0056] The following table provides a comparison of the timing of an example of the pilot injection mode and an example of the main injection mode:

[0057]

[0058] The pilot injection mode can have, for example, an injection start pressure of 30 Mpa to 40 Mpa, optionally 35 Mpa.

[0059] In some embodiments, the method can further include enabling a cylinder deactivation mode during cranking of the engine, where in the cylinder deactivation mode one or more cylinders of the engine are deactivated.

[0060] In the cylinder deactivation mode, one or two pairs of cylinders can be deactivated, optionally, the outermost one or two pairs of cylinders can be deactivated.

[0061] Figure 2 Four examples of configurations of deactivated cylinders are schematically shown. In a), an in-line 6 cylinder engine is shown with a deactivation mode in which one pair (the outermost pair) is deactivated (shown in shading) while the remaining cylinders are active (shown non-shading).

[0062] In b), an in-line 8 cylinder engine is shown with a deactivation mode in which two pairs (the outermost pairs) are deactivated (shown in shading) while the remaining cylinders are active (shown non-shading).

[0063] In c), a V12 cylinder engine is shown with a deactivation mode in which two pairs (i.e., the outermost pair of each cylinder bank) are deactivated (shown in shading) while the remaining cylinders are active (shown non-shading).

[0064] In d), a V16 cylinder engine is shown with a deactivation mode in which four pairs (i.e., the outermost two pairs of each cylinder bank) are deactivated (shown in shading) while the remaining cylinders are active (shown non-shading).

[0065] The cylinder deactivation mode can be enabled during cranking of the engine 40 in conjunction with the enabling of the pilot injection mode as described above. In some embodiments, the cylinder deactivation mode can always be enabled during cranking of the engine 40 without any error conditions. Alternatively, the cylinder deactivation mode can be enabled during cranking depending on one or more entry conditions being met.

[0066] As discussed further below, the cylinder deactivation mode can also be enabled during an idle of the engine 40 and / or during a low load condition of the engine 40.

[0067] The cylinder deactivation mode can be enabled at the start of cranking or after a time delay after the start of cranking. The cylinder deactivation mode can remain enabled for the remainder of the cranking of the engine 40. In some embodiments, the cylinder deactivation mode can be enabled for the entire cranking period.

[0068] Optionally, the cylinder deactivation mode can be deactivated during cranking according to one or more threshold values or variables or upon encountering one or more error conditions.

[0069] A non-limiting example of the activation and deactivation of the cylinder deactivation mode will now be described.

[0070] Figure 3 A schematic diagram illustrating an embodiment of the cylinder deactivation mode according to the present disclosure.

[0071] At step 1, an engine start instruction is provided. As described above, the engine start instruction can comprise actuation of a virtual or physical key, a switch, a button or other actuator.

[0072] At step 2, the controller 41 can check if the ON condition for the cylinder deactivation mode is considered OK. The ON condition can be considered “OK” when one or more of the following statements are TRUE:

[0073] • The cylinder deactivation mode is ON in the controller 41;

[0074] • No fault condition is detected in the fuel injectors associated with the cylinders 42 of the engine 40;

[0075] • No fault condition associated with the engine speed 43 or engine speed sensor is detected; and

[0076] • The engine speed 43 is not zero.

[0077] Optionally, the ON condition can be considered OK only if all the above statements are TRUE.

[0078] Only if the ON condition is considered “OK”, the cylinder deactivation mode can be turned ON.

[0079] If the ON condition is considered “OK”, the method can move to step 3.

[0080] If at step 2, the ON condition is not considered OK, the method can move to step 10 via arrow 21. At step 10, the controller can designate the cylinder deactivation mode as OFF. Then, the method can move to step 11 in which the engine 40 can be cranked and / or run with the cylinder deactivation mode deactivated (i.e. all cylinders 42 of the engine 40 are active) until the engine 40 is stopped by operation of the key (or other actuator).

[0081] At step 3, with the ON condition considered OK, the controller 41 can check if the entry condition for the cylinder deactivation mode is MET. The entry condition can be considered “MET” when one or more of the following statements are TRUE:

[0082] • The engine coolant temperature 44 is below or equal to an engine coolant temperature threshold;

[0083] • the engine intake manifold temperature 45 is lower than or equal to an engine intake manifold temperature threshold; and

[0084] • the engine load factor 46 is lower than or equal to an engine load factor threshold.

[0085] Optionally, the entry condition can be considered MET only if all of the above statements are TRUE.

[0086] The cylinder deactivation mode can be entered only if the entry condition is considered MET.

[0087] The engine coolant temperature threshold can be set at a temperature of -60°C to 150°C, optionally -40°C to 90°C. The engine intake manifold temperature threshold can be set at a temperature of -60°C to 300°C, optionally -40°C to 60°C. The engine load factor threshold can be set at a percentage of 0 to 120%, optionally 1 to 100%.

[0088] Optionally, one or more of the variables of the engine speed 43, the engine coolant temperature 44, the engine intake manifold temperature 45, and the engine load factor 46 can be associated with a de-bounce variable that can act to prevent the controller 41 from invoking the respective variable too frequently or acting on the respective variable that exceeds its threshold too quickly. For example, the variable of the engine coolant temperature 44 can have a de-bounce variable set at a time of 0 seconds to 60 seconds. For example, the engine intake manifold temperature 45 can have a de-bounce variable set at a time of 0 seconds to 60 seconds. For example, the engine load factor 46 can have a de-bounce variable set at a time of 0 seconds to 10 seconds.

[0089] At step 3, if the entry condition is MET, the method can move to step 4.

[0090] At step 3, if the entry condition is NOT MET, the method can move to step 10 via arrow 22. At step 10, the controller can designate the cylinder deactivation mode as OFF. The method can then move to step 11, in which the engine 40 can be cranked or run with the cylinder deactivation mode deactivated until the engine 40 is stopped by operation of the key (or other actuator).

[0091] At step 4, the controller 41 can determine whether the engine speed 43 is lower than or equal to an engine speed threshold. The engine speed threshold can be a speed of 0 rpm to 2000 rpm.

[0092] At step 4, if engine speed 43 is below or equal to a threshold, the method can optionally move to step 10 via arrow 23. At step 10, the controller can designate the cylinder deactivation mode as OFF. The method can then move to step 11, in which the engine 40 can be cranking with the cylinder deactivation mode disabled (i.e., all cylinders of the engine 40 are active) until the engine 40 is stopped by operation of the key (or other actuator).

[0093] At step 4, the controller 41 can determine whether the engine 40 is cranking or running. If the engine 40 is cranking, the method can move to step 5 via arrow 24. If the engine 40 is running, the method can move to step 6 via arrow 25.

[0094] The controller 41 can determine whether the engine 40 is cranking or running, for example, by monitoring engine speed. The determining factor can be, for example, a designated rpm engine speed or a predetermined offset from a desired rpm engine speed. For example, if the desired running speed of the engine 40 (e.g., a fixed desired running speed) is 1800 rpm, the controller 41 can be configured to treat engine speeds below 1600 rpm as the engine 40 cranking and engine speeds above 1600 rpm as the engine 40 running, for example. In another example, the controller 41 can be configured to treat engine speeds within, for example, 100 rpm or 200 rpm of the desired running speed as the engine 40 running and all lower speeds as cranking. The controller 41 can be configured such that once the engine 40 is determined to be running, the engine 40 cannot be determined to be cranking until the engine 40 is shut off and restarted.

[0095] At step 5, the controller 41 can monitor the cranking function of the engine 40. As described above, the cranking function can be encountered during start-up of the engine 40.

[0096] At step 5, the controller 41 can check whether the ON condition for the cylinder deactivation mode is considered NOT OK. The ON condition can be considered NOT OK when one or more of the following statements are not NOT TRUE:

[0097] • the cylinder deactivation mode is ON in the controller 41;

[0098] • a fault condition is not detected in the fuel injector associated with a cylinder 42 of the engine 40;

[0099] • a fault condition associated with the engine speed 43 or engine speed sensor is not detected;

[0100] • the engine speed 43 is not zero;

[0101] • the cylinder cut-off mode has been active for more than 10 to 30 seconds.

[0102] Optionally, the enable condition can be considered NOT OK only if any of the above statements is not TRUE.

[0103] If the enable condition is considered NOT OK, the method can move to step 10. At step 10, the controller can designate the cylinder cut-off mode as OFF. Then, the method can move to step 11, in which the engine 40 can run with the cylinder cut-off mode deactivated (i.e. all cylinders 42 of the engine 40 are active) until the engine 40 is stopped by operation of the key (or other actuator).

[0104] Additionally or alternatively, the method can move to step 10 via arrow 26 if the controller 41 no longer requests the cylinder cut-off mode, for example if the engine 40 is in a droop mode. The droop mode can be used as an engine load vs. speed factor characteristic, which allows the engine 40 to receive a load as a function of the engine speed. This can be used as an open loop engine regulator.

[0105] At step 5, if the enable condition is OK and the controller 41 still requests the cylinder cut-off mode, the cylinder cut-off mode can be enabled during cranking and run to the desired engine speed.

[0106] At step 5, if during cranking the engine coolant temperature 44 exceeds the aforementioned engine coolant temperature threshold, the method can move to step 7 via arrow 28. At step 7, the cylinder cut-off mode can be suspended (i.e. any deactivated cylinders 42 can be re-enabled) until the engine coolant temperature 44 returns below the engine coolant temperature threshold. Optionally, a coolant temperature hysteresis variable can be provided. The coolant temperature hysteresis variable can be for example 20°C. Optionally, the method can return to step 5 via arrow 28 only when the engine coolant temperature 44 has returned to a temperature equal to ‘the engine coolant temperature threshold minus the coolant temperature hysteresis variable’ below. For example, when:

[0107] • the engine coolant temperature threshold = 90°C

[0108] • the coolant temperature hysteresis variable = 20°C

[0109] When the engine coolant temperature 44 exceeds 90°C, the cylinder deactivation mode will be suspended and once the engine coolant temperature 44 returns to below 70°C (90°C - 20°C = 70°C), the cylinder deactivation mode will be re-enabled.

[0110] As mentioned above, the engine coolant temperature 44 can have a debouncing variable set to a time of 0 seconds to 60 seconds. As such, unless the engine coolant temperature 44 remains above the engine coolant temperature threshold for at least the period set to the debouncing variable, the method can not move from step 5 to step 7.

[0111] At step 5, once the cranking has been completed, the method can move to step 6 via arrow 27. As mentioned above, the point of moving from step 5 to step 6 can be determined by the controller 41 by monitoring the engine speed. The deciding factor can be, for example, a specified rpm engine speed or a predetermined offset from the desired rpm engine speed.

[0112] As mentioned above, the cylinder deactivation mode can also be enabled or remain enabled during periods of idling of the engine 40 and / or during low load conditions of the engine 40.

[0113] At step 6, the controller 41 can monitor for an idling mode of the engine 40. The idling mode can be encountered, for example, during operation of the engine 40 after the cranking start-up and in particular can be encountered during periods of idling of the engine 40 or when the engine is under low load conditions.

[0114] At step 6, if during the idling, the engine load factor 46 exceeds the aforementioned engine load factor threshold, the method can move to step 9 via arrow 33, where the controller 41 can monitor for a loading function of the engine 40. As mentioned above, the engine load factor 46 can have a debouncing variable set to a time of 0 seconds to 10 seconds. As such, unless the engine load factor 46 remains above the engine load factor threshold for at least the period set to the debouncing variable, the method can not move from step 6 to step 9.

[0115] At step 6, if during the idling, the engine coolant temperature 44 exceeds the aforementioned engine coolant temperature threshold, the method can move to step 7 via arrow 29. Step 7 functions in the same manner as described above, except that when the engine coolant temperature 44 returns to below the engine coolant temperature threshold or the engine coolant temperature threshold plus the coolant temperature hysteresis variable, the method can return to step 6 via arrow 29. The movement from step 6 to step 7 can include a debouncing variable as discussed above with respect to the movement from step 5 to step 7.

[0116] At step 6, if, during idle, the engine speed 43 exceeds the desired engine speed (e.g., the desired engine idle speed) by a greater than an engine speed threshold, the method can proceed to step 8 via arrow 30, where the controller 41 can suspend the cylinder cut-off mode (i.e., temporarily reactivate any deactivated cylinder 42). The engine speed threshold can be a fixed rpm value, a percentage of the desired engine speed rpm, etc. For example, the engine speed threshold can be set to a value from 1 rpm to 300 rpm. In one example, the threshold is set to 30 rpm.

[0117] At step 8, once the engine speed 43 has returned to within the desired engine speed threshold, the method can return to step 6, optionally continuing the de-chirping time. The cylinder cut-off mode may not be paused upon returning to step 6. The de-chirping time can be, for example, from 0 seconds to 10 seconds.

[0118] The controller 41 can be configured with a pause limit variable to limit the number of times the method accesses step 8 before the cylinder cutoff mode is completely disabled, until the engine 40 stops and restarts. For example, the pause limit variable could be 2, 3, 4, or 5.

[0119] For example, when:

[0120] Desired engine idle speed = 1200 rpm

[0121] Engine speed threshold = 200 rpm

[0122] Dejitter time = 5 seconds

[0123] Access Restriction = 2

[0124] The function of this method is as follows:

[0125]

[0126] At step 9, the controller 41 can monitor the loading function of the engine 40. For example, a loading function may be encountered during the operation of the engine 40 when the engine is under medium or high load conditions.

[0127] At step 6 and / or step 9, controller 41 may check whether the activation condition for the cylinder cut-off mode is considered NOT OK. The activation condition may be considered NOT OK when one or more of the following statements are not NOT TRUE:

[0128] • Activate the cylinder cut-off mode in controller 41;

[0129] No fault condition was detected in the fuel injector associated with cylinder 42 of engine 40;

[0130] • no fault condition associated with engine speed 43 or engine speed sensor is detected;

[0131] • engine speed 43 is not zero;

[0132] Optionally, the enable condition can be considered NOT OK only if any of the above statements is not TRUE.

[0133] If the enable condition is considered NOT OK, the method can move from step 6 and / or step 9 to step 10 via the respective arrows 32 and 34. At step 10, the controller can designate the cylinder cut-off mode as OFF. The method can then move to step 11, in which the engine 40 can be operated with the cylinder cut-off mode deactivated (i.e. all cylinders 42 of the engine 40 are active) until the engine 40 is stopped by operation of the key (or other actuator).

[0134] Additionally or alternatively, the method can move to step 10 via the respective arrows 32 and 34 if the controller 41 no longer requests the cylinder cut-off mode, for example if the engine 40 is in a derated mode.

[0135] Additionally or alternatively, the method can move to step 10 via the respective arrows 32 and 34 if the engine speed 43 exceeds an engine speed maximum threshold of the engine 40 (which can for example be 50 rpm above the rated maximum speed of the engine) and / or if the engine load factor 46 exceeds an engine load factor maximum threshold of the engine 40 (which can for example be 25% above the maximum rated load factor of the engine).

[0136] Additionally or alternatively, the method can move to step 10 via the respective arrows 32 and 34 if the controller 41 detects that the ability of the cylinders to combust fuel is impaired and / or if the controller 41 detects that a Controller Area Network (CAN) bus message is received indicating that a load is intended to be applied to the engine 41.

[0137] In some embodiments of the present disclosure, a method of controlling a cylinder cut-off mode for a fixed speed engine 40 is provided, the method comprising the steps of:

[0138] a) enabling the cylinder cut-off mode, wherein one or more cylinders 42 of the engine 40 are deactivated while one or more cylinders 42 of the engine 40 remain enabled;

[0139] b) injecting a main injection and optionally one or more pilot injections into the one or more enabled cylinders 42 during each cylinder cycle while the cylinder cut-off mode remains active; and

[0140] c) When the cylinder cut-off mode remains active, one or more ignition injections are performed during each cylinder cycle, but the main injection is not performed into the one or more deactivated cylinders 40.

[0141] This method can be specifically applied during the operation of engine 40, that is, after the engine 40 has been started and the engine speed has reached or substantially reached the fixed speed of engine 40. However, this method can also be applied alternatively during the starting of engine 40.

[0142] This method can be applied during engine operation, regardless of whether the cylinder cut-off mode is activated during engine start-up.

[0143] One or more ignition injections into one or more deactivated cylinders 42 may be injected at 30° to 40°, optionally at 35° BTDC.

[0144] One or more ignition injections injected into one or more deactivated cylinders 42 may be injected at an angle of 10° to 30° prior to the main injections injected into one or more deactivated cylinders 42.

[0145] One or more ignition injections into one or more deactivated cylinders 42 may have a diameter of less than 50 mm. 3 Optionally less than 40mm 3 Optional 20mm 3 Up to 40mm 3 Optional 25mm 3 Up to 35mm 3 Optional 30mm 3 The total volume of each cylinder per cycle.

[0146] One or more ignition injections injected into one or more deactivated cylinders 42 may have a per-cycle total volume of 10% to 25% of the main injection volume injected into one or more activated cylinders 42.

[0147] The main jet can be sprayed at 3° to 7°, optionally at 5° BTDC.

[0148] Industrial applicability

[0149] This disclosure can be applied to a fixed-speed engine and methods for starting a fixed-speed engine by rotation and controlling the cylinder cut-off mode of a fixed-speed engine.

[0150] The engine can be an internal combustion engine (ICE). ICEs can use diesel fuel as their primary fuel. In some examples, the engine can be a diesel generator set engine.

[0151] The present application can find particular benefit when the engine is operated in cold conditions, for example when the ambient temperature around the engine is less than 10°C. Under such conditions, starting the engine without a start assist device can be a challenge, particularly for ICEs that use diesel as the primary fuel. For example, under cold conditions, there can be a number of cylinders that do not fire until load is applied to the engine or the engine coolant warms up. Poor incomplete combustion can lead to adverse conditions such as increased vibration, noise and white smoke emissions - indicative of unburnt hydrocarbons.

[0152] According to the present disclosure, there is provided a method of cranking a stationary speed engine, the method comprising the steps of:

[0153] a) providing an engine start instruction;

[0154] b) enabling one or more cylinders of the stationary speed engine; and

[0155] c) enabling a pilot injection mode during cranking of the engine

[0156] wherein in the pilot injection mode, each cylinder cycle of the one or more enabled cylinders comprises one or more pilot injections followed by a main injection.

[0157] Beneficially, the one or more pilot injections can be injected at 13° to 17°, optionally at 15° BTDC. Beneficially, the one or more pilot injections can have a total volume per cycle per cylinder of 30mm 3 to 200mm 3 , optionally 30mm 3 to 80mm 3 , optionally 30mm 3 to 75mm 3 , optionally 35mm 3 , optionally 75mm 3 to 200mm 3 , optionally 80mm 3 to 200mm 3 . Beneficially, the one or more pilot injections can have a total volume per cycle per cylinder that is 10% to 25% of the main injection volume. Beneficially, the main injection can be injected at 3° to 7°, optionally at 5° BTDC. Beneficially, the main injection can have a total volume per cycle per cylinder of 300mm 3 to 800mm 3 . Beneficially, the method can further comprise disabling the pilot injection mode and commencing a main injection mode once the engine attains a speed within 250rpm of its stationary speed, optionally within 200rpm of its stationary speed, optionally within 100rpm of its stationary speed.

[0158] According to the present disclosure, there is also provided a fixed speed engine comprising a plurality of cylinders and a controller configured to, during cranking of the engine:

[0159] enable one or more cylinders of the fixed speed engine; and

[0160] enable a pilot injection mode;

[0161] wherein in the pilot injection mode, each cylinder of the one or more enabled cylinders comprises one or more pilot injections followed by a main injection.

[0162] Advantageously, the method and engine of the present disclosure can enable faster starting of a fixed speed engine, even in cold ambient conditions where the ambient temperature around the fixed speed engine is less than 10°C, thereby allowing for a reduction in cranking time. This can enable a reduction in total unburnt hydrocarbons (THC) emitted by the engine during cranking, and can also reduce vibration and noise of the engine.

[0163] Figure 4 and Figure 5 The following table provides test results for two engine configurations A and B, where configuration B is configured with a pilot injection mode according to the present disclosure to be enabled during cranking. In configuration A, during cranking, no pilot injection mode is active. In each configuration, the engine is a Perkins 4006-23TAG, a straight 6 cylinder engine with an engine displacement of 23 litres.

[0164] [Configuration] A B Pilot injection timing No 15° BTDC Main injection timing 15° BTDC 5° BTDC Rotational start time 14.5 seconds 6.5 seconds Peak THC 27 000 8 500

[0165] As shown, the use of the pilot injection mode according to the present disclosure results in a significantly faster start up for configuration B compared to 14.5 seconds for configuration A, resulting in an engine speed of 1500 rpm being achieved within 6.5 seconds after engine start up. Additionally, total unburnt hydrocarbons are significantly reduced for both peak and total counts for configuration A.

[0166] In another test using the same engine, the timing of the main injection was varied for engines running the pilot injection mode according to the present disclosure:

[0167] Pilot injection timing Main injection timing Rotational start time 15° BTDC 2° BTDC 40 seconds 15° BTDC 5° BTDC 17 seconds 15° BTDC 10° BTDC 30 seconds

[0168] As shown, the use of the pilot injection mode according to the present disclosure was found to be particularly beneficial when combined with a main injection timing of 3° to 7°, preferably 5° BTDC.

[0169] According to the present invention, there is provided a method of controlling a cylinder deactivation mode for a fixed speed engine, the method comprising the steps of:

[0170] a) enabling a cylinder deactivation mode, wherein one or more cylinders of the engine are deactivated, while one or more cylinders of the engine remain enabled;

[0171] b) injecting a main injection and optionally one or more pilot injections into the one or more enabled cylinders during each cylinder cycle while the cylinder deactivation mode remains active; and

[0172] c) injecting one or more pilot injections but not a main injection into the one or more deactivated cylinders during each cylinder cycle while the cylinder deactivation mode remains active.

[0173] Beneficially, the one or more pilot injections injected into the one or more deactivated cylinders can be injected at 30° to 40°, optionally at 35° BTDC. Beneficially, the one or more pilot injections injected into the one or more deactivated cylinders can be injected at 10° to 30° before the main injection injected into the one or more enabled cylinders. Beneficially, the one or more pilot injections injected into the one or more deactivated cylinders can have a total volume per cycle per cylinder of less than 50mm 3 , optionally less than 40mm 3 , optionally 20mm 3 to 40mm 3 , optionally 25mm 3 to 35mm 3 , optionally 30mm 3 . Beneficially, the one or more pilot injections injected into the one or more deactivated cylinders can have a total volume per cycle per cylinder of 10% to 25% of the volume of the main injection injected into the one or more enabled cylinders. Beneficially, the main injection can be injected at 3° to 7°, optionally at 5° BTDC.

[0174] According to the present disclosure, there is provided a fixed speed engine comprising a plurality of cylinders and a controller configured to:

[0175] a) enable a cylinder deactivation mode, wherein one or more cylinders of the engine are deactivated, while one or more cylinders of the engine remain enabled;

[0176] b) inject a main injection and optionally one or more pilot injections into the one or more enabled cylinders during each cylinder cycle while the cylinder deactivation mode remains active; and

[0177] c) injecting one or more pilot injections but no main injection into the one or more deactivated cylinders during each cylinder cycle while the cylinder deactivation mode remains active.

[0178] Advantageously, the method and engine of the present application are able to improve the transient response of the engine when transitioning from the cylinder deactivation mode being active to being deactivated. In particular, while the amount of the one or more pilot injections can not be sufficient to generate sufficient torque to maintain engine speed, it can be sufficient to burn and thus pre-heat the deactivated cylinders, meaning that when the deactivated cylinders are reactivated, the transient response will be improved. Thus, advantageously, even small volumes of pilot injection (e.g. less than 50mm 3 ) can be used to improve engine performance.

[0179] It will be appreciated that at least some of the drawings and description of the present disclosure have been simplified to focus on elements that are deemed to be pertinent for a clear understanding of the present disclosure, while other elements that would be understood by those skilled in the art have been omitted for the sake of brevity and clarity. Descriptions of these elements are not provided herein as they are deemed to be known to those skilled in the art, and because they do not necessarily contribute to a better understanding of the present disclosure.

[0180] Other embodiments of the present disclosure are set forth in the following clauses:

[0181] A1. A method of cranking a fixed speed engine, the method comprising the steps of:

[0182] a) providing an engine crank instruction;

[0183] b) activating one or more cylinders of the fixed speed engine; and

[0184] c) activating a pilot injection mode during cranking of the engine

[0185] wherein in the pilot injection mode, each cylinder cycle of the one or more activated cylinders comprises one or more pilot injections followed by a main injection.

[0186] A2. The method of clause A1, wherein the one or more pilot injections are injected at 13° to 17°, optionally at 15°, BTDC.

[0187] A3. The method of clause A1 or clause A2, wherein the one or more pilot injections have a volume of 30mm 3 to 200mm 3 , optionally 30mm 3 to 80mm 3 , optionally 30mm 3 to 75mm 3 , optionally 35mm3 , optionally 75 mm 3 to 200 mm 3 , optionally 80 mm 3 to 200 mm 3 of total volume per cylinder per cycle.

[0188] A4. The method of any preceding clause, wherein the one or more pilot injections have a total volume per cylinder per cycle of 10% to 25% of the volume of the main injection.

[0189] A5. The method of any preceding clause, wherein the main injection is injected at 3° to 7°, optionally at 5°, BTDC.

[0190] A6. The method of any preceding clause, wherein the main injection has a total volume per cylinder per cycle of 300 mm 3 to 800 mm 3 .

[0191] A7. The method of any preceding clause, further comprising deactivating the pilot injection mode and starting a main injection mode once the engine attains a speed within 250 rpm of its fixed speed, optionally within 200 rpm of its fixed speed, optionally within 100 rpm of its fixed speed.

[0192] A8. The method of any preceding clause, wherein in the pilot injection mode, the injection start pressure is 30 MPa to 40 MPa, optionally 35 MPa.

[0193] A9. The method of any preceding clause, further comprising activating a cylinder deactivation mode during the cranking of the engine;

[0194] wherein in the cylinder deactivation mode, one or more cylinders of the engine are deactivated.

[0195] A10. The method of clause A9, wherein in the cylinder deactivation mode, one or two pairs of cylinders are deactivated, optionally the outermost one or two pairs of cylinders are deactivated.

[0196] A11. The method of any preceding clause, wherein the fixed speed engine has a fixed speed of 1500 rpm to 1800 rpm.

[0197] A12. The method of any preceding clause, wherein the fixed speed engine is a diesel engine.

[0198] A13. The method of any preceding clause, wherein the fixed speed engine has a compression ratio of less than 14:1.

[0199] A14. The method of any preceding clause, wherein the fixed speed engine has a power density greater than 20 bar gross BMEP, optionally greater than 28 bar gross BMEP, optionally greater than 30 bar gross BMEP.

[0200] A15. The method of any preceding clause, wherein the fixed speed engine has a cylinder displacement of 3 liters or more liters per cylinder; and / or

[0201] wherein the fixed speed engine has an engine displacement of 23 liters or more, optionally 23 liters to 61 liters.

[0202] A16. The method of any preceding clause, wherein an ambient temperature surrounding the fixed speed engine is less than 10 °C.

[0203] A17. The method of any preceding clause, further comprising determining, based on one or more pilot injection mode entry conditions, whether to enable the pilot injection mode during the cranking of the engine upon receiving the engine start instruction; wherein the one or more pilot injection mode entry conditions are based on at least an engine coolant temperature.

[0204] A18. The method of clause A17, wherein if the determination is not to enable the pilot injection mode, then enabling a main injection mode during the cranking of the engine such that each cylinder cycle includes a main injection but no pilot injection.

[0205] A19. The method of clause A9 or clause A10, further comprising determining, based on one or more cylinder deactivation mode entry conditions, whether to enable the cylinder deactivation mode during the cranking of the engine; wherein the one or more cylinder deactivation mode entry conditions are based on one or more of an engine coolant temperature, an engine intake manifold temperature, and an engine load factor.

[0206] A20. A fixed speed engine comprising a plurality of cylinders and a controller configured to, during a cranking of the engine:

[0207] enable one or more cylinders of the fixed speed engine; and

[0208] enable a pilot injection mode;

[0209] wherein in the pilot injection mode, each cylinder cycle of the one or more enabled cylinders includes one or more pilot injections followed by a main injection.

[0210] A21. The fixed speed engine of clause A20, wherein the one or more pilot injections are injected at 13° to 17°, optionally at 15°, BTDC.

[0211] A22. The fixed speed engine of clause A21 or clause A22, wherein:

[0212] the fixed speed engine is a diesel engine, optionally a diesel genset engine; and / or

[0213] the fixed speed engine has a fixed speed of 1500 rpm to 1800 rpm; and / or

[0214] the fixed speed engine has a compression ratio of less than 14:1; and / or

[0215] the fixed speed engine has a power density of greater than 20 bar gross BMEP, optionally greater than 28 bar gross BMEP, optionally greater than 30 bar gross BMEP; and / or

[0216] the fixed speed engine has a cylinder displacement of 3 liters or more per cylinder; and / or

[0217] the fixed speed engine has an engine displacement of 23 liters or more, optionally 23 liters to 61 liters.

[0218] B1. A method of controlling a cylinder deactivation mode for a fixed speed engine, the method comprising the steps of:

[0219] a) enabling a cylinder deactivation mode, wherein one or more cylinders of the engine are deactivated while one or more cylinders of the engine remain enabled;

[0220] b) injecting a main injection and optionally one or more pilot injections into the one or more enabled cylinders during each cylinder cycle while the cylinder deactivation mode remains active; and

[0221] c) injecting one or more pilot injections but not a main injection into the one or more deactivated cylinders during each cylinder cycle while the cylinder deactivation mode remains active.

[0222] B2. The method of clause B1, wherein the one or more pilot injections injected into the one or more deactivated cylinders are injected at 30° to 40°, optionally at 35°, BTDC.

[0223] B3. The method of clause B1 or clause B2, wherein the one or more pilot injections injected into the one or more deactivated cylinders are injected 10° to 30° prior to the main injection injected into the one or more deactivated cylinders.

[0224] B4. The method of any of clauses B1-B3, wherein the one or more pilot injections into the one or more deactivated cylinders has a total volume per cycle per cylinder that is less than 50 mm 3 , optionally less than 40 mm 3 , optionally 20 mm 3 to 40 mm 3 , optionally 25 mm 3 to 35 mm 3 , optionally 30 mm 3 .

[0225] B5. The method of any of clauses B1-B4, wherein the one or more pilot injections into the one or more deactivated cylinders has a total volume per cycle per cylinder that is 10% to 25% of the volume of the main injection into the one or more activated cylinders.

[0226] B6. The method of any of clauses B1-B5, wherein the main injection is injected 3° to 7°, optionally 5°, BTDC.

[0227] B7. The method of any of clauses B1-B6, wherein when the cylinder cut-off mode is active, one or two pairs of cylinders are deactivated, optionally, the outermost one or two pairs of cylinders are deactivated.

[0228] B8. The method of any of clauses B1-B7, wherein the fixed speed engine has a fixed speed of 1500 rpm to 1800 rpm.

[0229] B9. The method of any of clauses B1-B8, wherein the fixed speed engine is a diesel engine.

[0230] B10. The method of any of clauses B1-B9, wherein the fixed speed engine has a compression ratio of less than 14:1.

[0231] B11. The method of any of clauses B1-B10, wherein the fixed speed engine has a power density of greater than 20 bar gross BMEP, optionally greater than 28 bar gross BMEP, optionally greater than 30 bar gross BMEP.

[0232] B12. The method of any of clauses B1-B11, wherein the fixed speed engine has a cylinder displacement of 3 liters or more per cylinder.

[0233] B13. The method of any of clauses B1-B12, wherein the fixed speed engine has an engine displacement of 23 liters or more, optionally 23 liters to 61 liters.

[0234] B14. The method of any of clauses B1-B13, wherein the ambient temperature around the fixed speed engine is less than 10°C.

[0235] B15. A fixed speed engine comprising a plurality of cylinders and a controller configured to:

[0236] a) enable a cylinder shut down mode in which one or more cylinders of the engine are deactivated while one or more cylinders of the engine remain enabled;

[0237] b) inject a main injection and optionally one or more pilot injections into the one or more enabled cylinders during each cylinder cycle while the cylinder shut down mode remains active; and

[0238] c) inject one or more pilot injections but not a main injection into the one or more deactivated cylinders during each cylinder cycle while the cylinder shut down mode remains active.

[0239] B16. The fixed speed engine of clause B15, wherein:

[0240] the fixed speed engine is a diesel engine, optionally a diesel genset engine; and / or

[0241] the fixed speed engine has a fixed speed of 1500 rpm to 1800 rpm; and / or

[0242] the fixed speed engine has a compression ratio of less than 14:1; and / or

[0243] the fixed speed engine has a power density of greater than 20 bar gross BMEP, optionally greater than 28 bar gross BMEP, optionally greater than 30 bar gross BMEP; and / or

[0244] the fixed speed engine has a cylinder displacement of 3 liters or more per cylinder; and / or

[0245] the fixed speed engine has an engine displacement of 23 liters or more, optionally 23 liters to 61 liters.

[0246] C1. A method of controlling a fixed speed engine, the method comprising the method of cranking a fixed speed engine of any of clauses A1-A19 and the method of controlling a cylinder shut down mode of a fixed speed engine of any of clauses B1-B14.

[0247] D1. The fixed speed engine of any of clauses A20-A22 and clause B15.

Claims

1. A method for starting a fixed-speed engine by rotation, the method comprising the following steps: a) Provide engine start command; b) Activating one or more cylinders of the fixed-speed engine; and c) Activate the ignition injection mode during the engine's rotational start-up; In the ignition injection mode, each cylinder cycle of the one or more activated cylinders includes one or more ignition injections, followed by the main injection. The method also includes enabling a cylinder cut-off mode during the engine's rotational start-up. In the cylinder cut-off mode, one or more cylinders of the engine are deactivated; When the cylinder cut-off mode remains active, one or more ignition injections are performed during each cylinder cycle, but the main injection is not delivered to one or more deactivated cylinders; and The primary or secondary ignition injections are carried out at 13° to 17° BTDC, and the main injection is carried out at 3° to 7° BTDC.

2. The method of claim 1, wherein the one or more ignition injections are performed at a 15° BTDC.

3. The method of claim 1 or claim 2, wherein the one or more ignition injections have a diameter of 30 mm. 3 Up to 200 mm 3 The total volume of each cylinder per cycle.

4. The method of claim 3, wherein the one or more ignition injections have a diameter of 30 mm. 3 Up to 80 mm 3 The total volume of each cylinder per cycle.

5. The method of claim 4, wherein the one or more ignition injections have a diameter of 30 mm. 3 Up to 75 mm 3 The total volume of each cylinder per cycle.

6. The method of claim 5, wherein the one or more ignition injections have a diameter of 35 mm. 3 The total volume of each cylinder per cycle.

7. The method of claim 3, wherein the one or more ignition injections have a diameter of 75 mm. 3 Up to 200 mm 3 The total volume of each cylinder per cycle.

8. The method of claim 7, wherein the one or more ignition injections have an 80 mm diameter. 3 Up to 200 mm 3 The total volume of each cylinder per cycle.

9. The method of claim 1 or claim 2, wherein the one or more ignition injections have a total volume per cycle per cylinder of 10% to 25% of the volume of the main injection.

10. The method of claim 1 or claim 2, wherein the main jet is injected at 5° BTDC.

11. The method of claim 1 or claim 2, wherein the main jet has a diameter of 300 mm. 3 Up to 800 mm 3 The total volume of each cylinder per cycle.

12. The method of claim 1 or claim 2, further comprising deactivating the ignition injection mode and initiating the main injection mode once the engine reaches a speed within 250 rpm of its fixed speed.

13. The method of claim 12, further comprising deactivating the ignition injection mode and initiating the main injection mode once the engine reaches a speed within 200 rpm of its fixed speed.

14. The method of claim 13, further comprising deactivating the ignition injection mode and initiating the main injection mode once the engine reaches a speed within 100 rpm of its fixed speed.

15. The method of claim 1 or claim 2, wherein in the ignition injection mode, the injection start pressure is 30 MPa to 40 MPa.

16. The method of claim 15, wherein in the ignition injection mode, the injection start pressure is 35 MPa.

17. The method of claim 1, wherein in the cylinder cut-off mode, one or two pairs of cylinders are deactivated.

18. The method of claim 17, wherein in the cylinder cut-off mode, the outermost pair or two pairs of cylinders are deactivated.

19. The method of claim 1 or claim 2, wherein the fixed-speed engine has a fixed speed of 1500 rpm to 1800 rpm.

20. The method of claim 1 or claim 2, wherein the fixed-speed engine is a diesel engine.

21. The method of claim 1 or claim 2, wherein the fixed-speed engine has a compression ratio of less than 14:

1.

22. The method of claim 1 or claim 2, wherein the fixed-speed engine has a power density greater than 20 bar total BMEP.

23. The method of claim 22, wherein the fixed-speed engine has a power density greater than 28 bar total BMEP.

24. The method of claim 23, wherein the fixed-speed engine has a power density greater than 30 bar total BMEP.

25. The method of claim 1 or claim 2, wherein the fixed-speed engine has a cylinder displacement of 3 liters or more per cylinder; and / or The fixed-speed engine has a displacement of 23 liters or more.

26. The method of claim 25, wherein the fixed-speed engine has an engine displacement of 23 to 61 liters.

27. The method of claim 1 or claim 2, wherein the ambient temperature around the fixed-speed engine is less than 10°C.

28. A fixed-speed engine, the fixed-speed engine comprising a plurality of cylinders and a controller, the controller being configured to: Activating one or more cylinders of the fixed-speed engine; and Activate ignition injection mode; In the ignition injection mode, each cylinder cycle of the one or more activated cylinders includes one or more ignition injections, followed by the main injection. The controller is further configured to enable a cylinder cut-off mode during the engine's rotational start-up. In the cylinder cut-off mode, one or more cylinders of the engine are deactivated; When the cylinder cut-off mode remains active, one or more ignition injections are performed during each cylinder cycle, but the main injection is not delivered to one or more deactivated cylinders; and The primary or secondary ignition injections are carried out at 13° to 17° BTDC, and the main injection is carried out at 3° to 7° BTDC.

29. The fixed-speed engine of claim 28, wherein the one or more ignition injections are 13° to 17° BTDC injections.

30. The fixed-speed engine of claim 29, wherein the one or more ignition injections are performed at a 15° BTDC.

31. The fixed-speed engine as claimed in any one of claims 28-30, wherein: The fixed-speed engine is a diesel engine; and / or The fixed-speed engine has a fixed speed of 1500 rpm to 1800 rpm; and / or The fixed-speed engine has a compression ratio of less than 14:1; and / or The fixed-speed engine has a power density greater than 20 bar total BMEP; and / or The fixed-speed engine has a cylinder displacement of 3 liters or more per cylinder; and / or The fixed-speed engine has an engine displacement of 23 liters or more.

32. The fixed-speed engine as claimed in claim 31, wherein, The fixed-speed engine is a diesel generator set engine.

33. The fixed-speed engine as claimed in claim 31, wherein, The fixed-speed engine has a power density greater than 28 bar total BMEP.

34. The fixed-speed engine as claimed in claim 33, wherein, The fixed-speed engine has a power density greater than 30 bar total BMEP.

35. The fixed-speed engine as claimed in claim 31, wherein, The fixed-speed engine has a displacement of 23 to 61 liters.

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