Cooling system for a gas engine piston, gas engine, cooling method for a gas engine piston

Abstract

Cooling system (10) for a gas engine piston (100) for the combustion of hydrogen or hydrogen / hydrocarbon gas mixtures, the system comprising: a piston cooling device (12) configured to spray a cooling oil flow (14) from a first position (P1) and / or at least a second position (P2); and a control device (16) configured to control the piston cooling device (12) to the first and / or second position (P1, P2) based on at least one specified parameter (18).

Description

field of technology

[0001] The present invention relates to a cooling system for cooling a gas engine piston suitable for the combustion of hydrogen or hydrogen / hydrocarbon gas mixtures. The present disclosure also relates to a gas engine comprising such a cooling system. Furthermore, the present disclosure relates to a cooling method for cooling a gas engine piston suitable for the combustion of hydrogen or hydrogen / hydrocarbon gas mixtures. Technological state of the art

[0002] Growing awareness of the impacts associated with emissions from conventional fossil fuels has made natural gas (NG) an attractive alternative to internal combustion engines, particularly because it is environmentally friendly, clean-burning, economical and efficient.

[0003] Hydrogen and hydrocarbon gases are considered a viable option for making gas engine exhaust gases even cleaner. However, operating gas engines with hydrogen or hydrogen / hydrocarbon gas mixtures also carries the risk of potentially adverse effects associated with the combustion of hydrogen in gas engines.

[0004] The gas engine piston cooling system, gas engine, and gas engine piston cooling method of the present disclosure solve one or more of the problems set forth above. Brief description of the invention

[0005] Based on the state of the art, the goal is to provide a simple, cost-effective, and reliable cooling system for a gas engine piston suitable for the combustion of hydrogen or hydrogen / hydrocarbon gas mixtures. Furthermore, self-ignition caused by glow spots in gas engine pistons should be reliably prevented.

[0006] This object is achieved by a cooling system for a gas engine piston having the features of claim 1, a gas engine having such a system having the features of claim 14 and a cooling method for a gas engine piston having the features of claim 15. Preferred embodiments are set out in the present description, the figures and the dependent claims.

[0007] Accordingly, a cooling system for cooling a gas engine piston suitable for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures is provided. The cooling system comprises a piston cooling device configured to spray a cooling oil stream from a first position and / or from at least one second position, and a control device configured to control the piston cooling device to the first and / or second position based on at least one predetermined parameter.

[0008] Furthermore, a gas engine for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures is provided. The gas engine comprises at least one gas engine piston and a cooling system according to the present disclosure.

[0009] In terms of methodology, a cooling method for cooling a gas engine piston suitable for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures is provided, comprising a piston cooling device configured to spray a cooling oil stream from a first position and at least one second position. The method according to the present disclosure comprises the steps of receiving a predetermined parameter at the control device, controlling the piston cooling device to the first and / or second position based on the at least one predetermined parameter, such that cooling oil deposits on a gas engine piston surface are burned to ash. Short description of the drawings.

[0010] The present disclosure will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which: Fig. 1 schematically shows a cooling system for a gas engine piston according to a first embodiment; Fig. 2 schematically shows a cooling system for a gas engine piston according to another embodiment; Fig. 3 schematically shows a cooling system for a gas engine piston according to another embodiment; Fig. 4 schematically shows a cooling system for a gas engine piston according to a further development; Fig. 5 schematically shows a cooling system for a gas engine piston according to another embodiment; Fig. 6 shows a first embodiment of a piston cooling device suitable for the cooling system, in a plan view; Fig. 7 shows a second embodiment of a piston cooling device suitable for the cooling system, in a side view; Fig. 8 schematically shows a gas engine with a cooling system according to the first embodiment; and Fig. 9 schematically shows a flow diagram of a cooling method according to a first embodiment. Detailed description of the preferred embodiments

[0011] The invention will be explained in more detail below with reference to the accompanying figures. Similar elements are identified by identical reference numerals, and a repeated description thereof may be omitted to avoid redundancy.

[0012] The present disclosure generally relates to piston cooling applications for cooling a gas engine piston suitable for combusting hydrogen and / or hydrogen / hydrocarbon mixtures as fuel gas. According to one example, such a gas engine piston may be suitable for a fuel gas comprising only hydrogen, such as used in H2 gas engines. According to another example, the piston may be suitable for a fuel gas comprising a hydrogen / hydrocarbon mixture with a specific hydrogen / hydrocarbon gas ratio.

[0013] It has been found that hydrogen and hydrogen / hydrocarbon gas mixtures can offer better flame speeds, a wider flammability range, lower minimum ignition energy and / or lower emissions.

[0014] Compared to natural gas combustion, hydrogen combustion generates less heat per gas volume. When hydrogen is burned in-cylinder, piston cooling requirements may differ from those for natural gas combustion. In particular, it has been found that using a specific gas engine piston with piston cooling adapted for natural gas combustion and operating this piston with hydrogen can result in lower piston temperatures. This effect has also been observed for gas engine pistons operating with hydrogen / hydrocarbon gas mixtures.

[0015] During the combustion of natural gas in a gas engine, the temperature of the gas engine piston is high enough to burn any cooling oil residue to ash. However, it has been observed that lower piston temperatures, such as those observed during the combustion of hydrogen, can lead to conditions where cooling oil residue on the piston is not burned to ash during combustion. Instead, cooling oil residue has been observed to remain in place as partially burned cooling oil coke deposits. Often, such partially burned cooling oil coke deposits form glow spots that can trigger pre-ignition or auto-ignition in the following combustion cycle. In general, cooling oil coke deposits tend to glow for much longer than ash, posing a much greater risk of acting as glow spots in a subsequent combustion cycle.

[0016] In other words, reaching piston temperatures that are too low can lead to self-ignition and ultimately engine failure. If, however, the piston surface temperatures are maintained at a sufficiently high temperature, cooling oil residues on the piston surfaces are burned to ash without the formation of hot spots.

[0017] Therefore, improved gas engine piston cooling devices are needed to compensate for the lower heat release observed during the combustion of weak, hydrogen-containing fuel gases.

[0018] In Fig. 1 schematically shows a cooling system 10 for a gas engine piston 100. The cooling system 10 comprises a piston cooling device 12 configured to spray a cooling oil stream 14 onto the gas engine piston 100 from a first position P1 and / or from at least one second position P2. The cooling system 10 further comprises a control device 16 configured to control the piston cooling device 12 to the first and / or second position P1, P2 based on at least one predetermined parameter 18.

[0019] The gas engine piston 100 may be configured to be operable with a fuel gas 20, preferably a fuel gas 20 with different hydrogen / hydrocarbon gas ratios. For example, the fuel gas 20 may consist of air + H2 or air + H2 + C n H mThe gas engine piston 100 may be part of a gas engine, e.g., a gas engine of the internal combustion engine type, which burns the fuel gas 20 in a combustion chamber 150. The gas engine piston 100 may have a gas engine piston surface 140 facing the combustion chamber 150. The cooling oil used in the cooling oil flow 14 may be engine oil taken from an oil pan of the gas engine piston (in Fig. 1 not shown).

[0020] As shown in the illustration by Fig. 1, the first and second positions P1, P2 can be understood as two different spatial locations from which a cooling oil stream 14 is sprayed, preferably in the direction of the gas engine piston 100. However, the first and second positions P1, P2 can also be understood as two different orientations of a cooling oil spray. In other words, the two different positions can be understood as two different oil outlet positions and / or orientations of the cooling stream 14. In addition to the first position and the second position, the piston cooling device 12 can be further configured to spray a cooling oil stream from a first, second, and nth position P1, P2, Pn.

[0021] Accordingly, providing a control device 16 configured to control the piston cooling device 12 to the first and / or second position P1, P2 can be understood as providing a control device 16 configured to control whether a cooling oil flow 14 is sprayed from the first position P1 and / or from the second position P2. For example, the control device 16 can be configured to direct, restrict, or allow a cooling oil flow 14 to be sprayed from the first and / or second position P1, P2 based on at least the specified parameter 18.

[0022] Depending on whether the control device 16 controls the piston cooling device 12 to the first position P1 and / or the second position P2, the cooling oil flow 14 can be sprayed from the first and / or second position P1, P2. In the illustration shown, the control device 16 controls the piston cooling device 12 to the first position P1 and the second position P2. Under normal conditions, however, the control device 16 can also control the piston cooling device 12 only to either the first position P1 or the second position P2.

[0023] The fact that the control is based at least on the specified parameter 18 means that although the control may depend on additional parameters or be a function of these parameters, it must be based on the specified parameter 18.

[0024] The specified parameter 18 may be one or more analog signals in the form of continuous signals representing physical measurements or inputs. Alternatively, the specified parameter may be a digital signal in the form of one or more time-separated signals generated by digital modulation. Furthermore, the specified parameter 18 may be an input signal of the control device 16. The specified parameter 18 may be a parameter that is specified prior to combustion. For example, the specified parameter 18 may be specified prior to operation of the gas engine piston 100 or prior to combustion of another fuel gas in the gas engine piston 100. Preferably, the specified parameter 18 may apply to an entire operating cycle of a gas engine piston, including the start-up and operating phases of the gas engine piston.

[0025] Using such a fixed parameter allows piston temperature control without relying exclusively on real-time parameters such as gas piston temperature. Furthermore, piston temperature can be controlled without relying exclusively on an engine operating condition, such as "start-up" or "rated operation."

[0026] By controlling the piston cooling device 12 to these different positions P1, P2, Pn based on at least one specified parameter, precise cooling of the gas engine piston 100 can be achieved, with the result that cooling oil deposits, for example, cooling oil coke deposits, are burned to ash during combustion. This prevents unburned cooling oil coke deposits from forming glow spots in a subsequent combustion cycle. Self-ignition due to glow spots can thus be avoided. This increases the operational reliability of the gas engine piston 100.

[0027] According to the Fig. 1, the first position P1 may be a position suitable for spraying the cooling oil stream 14 into a piston oil line 130. The second position P2 may be a position suitable for spraying the cooling oil 14 onto a piston bottom 120.

[0028] Depending on the position selected for the emanating spray of the cooling oil stream 14, the cooling system 10 can have different cooling capacities. For example, the cooling capacity can be high if the cooling oil stream 14 is sprayed from the first position P1 into the cooling oil line 130. Likewise, the cooling capacity can be lower if the cooling oil stream 14 is sprayed from the second position P2 onto the piston underside 120. The cooling capacity of the cooling system can be controlled based on at least the specified parameter 18.

[0029] For this purpose, the piston cooling device 12 may include a first cooling oil nozzle 13 configured to spray the cooling oil stream 14 from the first position P1. The piston cooling device 12 may further include a second cooling oil nozzle 15 configured to spray a cooling oil stream 14 from the second position P2. The first and second cooling oil nozzles 13, 15 may be configured identically, so that the spray formed by these nozzles 13, 15 has similar properties.

[0030] Alternatively, the first and second cooling oil nozzles 13, 15 may be shaped differently to accommodate different spraying characteristics when spraying the cooling oil stream 14.

[0031] In the Fig. 1, the first cooling oil nozzle 13 can be attached to a first arm 36 and the second cooling oil nozzle 15 can be attached to a second arm 38.

[0032] The first and second cooling oil nozzles 13, 15 can be offset from one another in a cooling oil flow direction. Furthermore, the first and second cooling oil nozzles 13, 15 can have a different orientation relative to one another.

[0033] In Fig. 2 shows an example of a cooling system 10 for a gas engine piston 100 according to another embodiment. Fig. The embodiment shown in Figure 2 differs from Fig. 1 in that the fixed parameter 18 can be a function of a fuel gas 20 and that the control device 16 consists of Fig. 2 can be configured to further control the piston cooling device 12 into the first and / or second position P1, P2 based on a gas piston temperature 110. The gas piston cooling device 12 can be controlled into the first and / or second position P1, P2 based on a gas piston temperature 110 and a fuel gas 20.

[0034] In a further embodiment, the specified parameter 18 may be a function of a fuel gas concentration 22, a hydrogen concentration 24, and / or a hydrogen / hydrocarbon fuel gas substitution ratio 25. Furthermore, the specified parameter 18 and the gas piston temperature 110 may be used as input to the control device 16. The specified parameter 18 may include the fuel gas concentration 22, the hydrogen concentration 24, and / or the hydrogen / fuel gas substitution ratio 25 as explicit or implicit information in an analog or digital signal, as in connection with Fig. 1 defined.

[0035] According to a further embodiment, which is also described in Fig. 2, the control device 16 can be configured such that the piston cooling device 12 is controlled to the second position P2 when the fuel gas 20 has a high hydrogen concentration 22, for example, a hydrogen concentration between 100 and 70 vol.%. Alternatively or additionally, the control device 16 can be configured such that the piston cooling device 12 is controlled to the first position P1 when the fuel gas 20 has a low hydrogen concentration 22, for example, a hydrogen concentration 22 between 0 and 70 vol.%.

[0036] In the context of the present disclosure, a high hydrogen concentration can be understood as a hydrogen concentration that would result in unburned cooling oil coke residues forming a glow spot during combustion in the gas engine piston if the gas engine piston were cooled from the first position P1. Likewise, a low hydrogen concentration can be understood as a hydrogen concentration that would not lead to glow spot-related cooling oil coking during combustion in the gas engine piston if the gas engine piston were cooled from the first position P1.

[0037] In this context, the hydrogen / hydrocarbon gas substitution ratio can be understood literally, assuming a fixed amount of air and natural gas that is partially replaced by molecular hydrogen. In the broadest sense, a hydrogen concentration and a hydrogen / hydrocarbon gas ratio can be used interchangeably.

[0038] Such configurations of the control device 16 are based on the observation that the presence of hydrogen in the fuel gas correlates positively with lower piston heating, thereby reducing the need for piston cooling.

[0039] More specifically, lower temperatures occur during the combustion of fuel gases with a higher hydrogen concentration or a higher hydrogen / hydrocarbon gas ratio than during the combustion of hydrocarbon gas mixtures such as natural gas. Due to the observed lower temperatures, cooling oil deposits on piston surfaces are burned to ash during combustion, but may instead remain in the form of partially burned, glowing cooling oil coke deposits. As a result, such cooling oil coke deposits can form glow spots and lead to pre-ignition during a subsequent combustion cycle. These phenomena can be avoided by the cooling system according to the present disclosure only to the extent that the temperature of the piston during combustion is sufficiently high that cooling oil residues are burned to ash.

[0040] In Fig. 3, a cooling system 10 according to another embodiment is shown. According to the Fig. 3, the cooling system 10 may further include a user input interface 26 configured to provide the specified parameter 18.

[0041] The user input interface 26 may be any device suitable for providing the specified parameter 18 in response to user input. For example, the user input interface 26 may be a device configured to provide the specified parameter 18 as a function of a fuel gas 20, as a function of the fuel gas concentration 22, as a hydrogen concentration 24, or as a hydrogen / hydrocarbon gas ratio 25. The user input 26 itself may consist of the specified parameter 18 itself or may be related to the specified parameter 18.

[0042] In Fig. 4, a cooling system 10 according to another embodiment is shown. Accordingly, the cooling system 10 may further include a hydrogen sensor 28 configured to provide the specified parameter 18. The hydrogen sensor 28 may, for example, be of the TCD type. The hydrogen sensor 28 may be configured to provide the specified parameter 18 without requiring user input. For example, the hydrogen sensor 28 may provide the specified parameter 18 in the form of an analog or digital signal representing a hydrogen concentration 24 or a hydrogen / hydrocarbon gas ratio 25.

[0043] The hydrogen sensor may be used as the sole source providing the specified parameter 18. Alternatively, the hydrogen sensor 28 may not be the sole source providing the specified parameter 18.

[0044] In Fig. 5 shows a cooling system 10 according to another embodiment. Fig. The embodiment shown in Figure 5 is based on the example shown in Fig. 2. The embodiment shown in Fig. However, the embodiment shown in Figure 5 is also compatible with any other Fig. 1 to Fig. 4 shown embodiment. Fig. 5 may further include a lookup table, correlation, and / or algorithm 30 configured to provide an output for controlling the piston cooling device 12 to the first and / or second position P1, P2. The output may further include a piston motor temperature 110.

[0045] The output may be a function of a pressure, in particular a cooling oil pressure. An output of the control device 16 may be adapted to an input of the cooling oil supply 12. The lookup table, the correlation, and / or the algorithm 30 may contain empirically obtained data.

[0046] According to a further embodiment, the control device 16 may further comprise signal modulation means configured to generate digital signals from analog signals.

[0047] Furthermore, the piston cooling device 12 may comprise more than one first and second cooling oil nozzle 13, 15.

[0048] In Fig. 6 shows an exemplary first embodiment of a piston cooling device 12 suitable for use in the cooling system 10, shown in a plan view. The piston cooling device 12 is configured to spray a cooling oil stream 14 from a first position P1 and / or from at least one second position P2. For this purpose, the piston cooling device 12 may include a first cooling oil nozzle 13 configured to spray the cooling oil stream 14 from the first position P1. The piston cooling device 12 may further include a second cooling oil nozzle 15 configured to spray the cooling oil stream 14 from the second position P2.

[0049] The first cooling oil nozzle 13 may be attached to a first arm 36, which includes a first cooling oil channel 40. Likewise, the second cooling oil nozzle 15 may be attached to a second arm 38, which includes a second cooling oil channel 42. As shown, the first and second cooling oil nozzles 13, 15 may be offset from one another. The offset extends in a direction parallel to the piston bottom (in Fig. 6 (not shown). Furthermore, the first and second cooling oil nozzles 13, 15 may be offset in a direction perpendicular thereto, which may be a direction of cooling oil spraying. The first and second cooling oil nozzles may have the same orientation, i.e., the spray jets formed at the first and second nozzles 13, 15 may move in the same direction, but from different spatial positions due to the offset.

[0050] The piston cooling device 12 may have a cooling oil valve 32 (in Fig. 6 not shown, see Fig. 7) configured to allow or block a cooling oil flow 14 into the first cooling oil channel 40 and / or the second cooling oil channel 42. The cooling oil valve 32 may be a pressure-actuated valve. For example, the cooling oil valve 32 may be configured such that, at a cooling oil pressure of 5 bar or more, the cooling oil flow 14 is directed to the first cooling nozzle 13. Thus, the cooling oil flow 14 can be sprayed from the first position P1. Likewise, the cooling oil valve 32 may be configured such that, at a cooling oil pressure below 5 bar, the cooling oil flow 14 is directed to the second cooling nozzle 15. Thus, the cooling oil flow 14 can be sprayed from the second position P2.

[0051] In Fig. 7 shows a side view of an exemplary second embodiment of a piston cooling device 12 suitable for the cooling system 10. This second embodiment differs from the one shown in Fig. 6 in that the piston cooling device 12 may comprise a rotatable nozzle 17 configured to be rotatable into the first position P1 and / or the at least second position P2. In other words, the piston cooling device 12 according to the second embodiment may comprise only a first arm 36 comprising a first cooling oil channel 40. Due to its rotatable configuration, for example, by a flexible or pivotable arm 36, the rotatable nozzle 17 can be brought into the first position P1 and at least the second position P2.

[0052] The piston cooling device 12 may include a cooling oil valve 32 configured to allow or block a cooling oil flow 14 in the first cooling oil channel 40. The cooling oil valve 32 may be a pressure-actuated valve. Furthermore, the rotatable nozzle 17 may be configured to be rotatable by pressure. For example, the cooling oil valve 32 may be configured such that, at a cooling oil pressure of 5 bar or more, the cooling oil flow 14 is directed into the cooling oil channel 40 and the rotatable nozzle 17 is in the first position P1. Thus, the cooling oil 14 can be sprayed from the first position P1. Likewise, the cooling oil valve 32 may be configured such that, at a cooling oil pressure below 5 bar, the cooling oil flow 14 is still directed into the cooling oil channel 40 and the rotatable nozzle 17 is in the second position P2. Thus, the cooling oil 14 can be sprayed from the second position P2.

[0053] According to both embodiments of the piston cooling device 12, the first position P1 may be a position suitable for directing the cooling oil flow 14 into an oil piston line 130 (in the Fig. 6 and Fig. 7 not shown), and the second position P2 may be a position suitable for spraying the cooling oil 14 onto a piston bottom 120 (in the Fig. 6 and Fig. 7 not shown). Therefore, the first position P1 can be suitable for operating conditions where a high cooling requirement must be met, e.g., when operating a gas engine piston with a fuel gas having a low hydrogen concentration. Likewise, the second position P2 can be suitable for operating conditions where a lower cooling requirement must be met, e.g., when operating a gas engine piston with a fuel gas having a high hydrogen concentration. This can achieve combustion of cooling oil residues to ash, with the result that pre-ignition or self-ignition of the fuel gas due to the glow point can be avoided. This can increase the operational reliability of a gas engine piston that uses hydrogen or hydrogen / hydrocarbon mixtures as the fuel gas.

[0054] Those skilled in the art will appreciate that the embodiments of the piston cooling device 12 can be combined with one another to configure the piston cooling device 12 such that a cooling oil stream 14 is sprayed from a first position P1 and / or from at least one second position P2 without departing from the present disclosure. For example, multiple nozzles may be provided, none, one, some, or all of which may be rotatable cooling oil nozzles.

[0055] The piston cooling device 12, in particular the cooling oil valve 32, can be configured such that the piston cooling device 12 is controlled to the first and / or second position P1, P2 once per operation, preferably once per fuel gas used. In particular, the control device 16 can be configured to control the piston cooling device 12 to the first and / or second position not based on an operating phase of the gas engine piston, such as start-up or nominal operation, but based on the specified parameter 18, in particular a fuel gas composition.

[0056] In Fig. 8, a gas engine 200 according to the present disclosure is shown. The gas engine 200 is suitable for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures and includes at least one gas engine piston 100 and a cooling system 10 according to the present disclosure. To this end, the same explanations, definitions, and principles explained above in connection with the cooling system 10 also apply to the gas engine 200. The gas engine piston 100 may include a gas engine piston surface 140 facing a combustion chamber 150.

[0057] Therefore, the gas engine 200 comprises a piston cooling device 12 configured to spray a cooling oil stream 14 from a first position P1 and / or at least one second position P2, and a control device 16 configured to control the piston cooling device 12 to the first and / or second position P1, P2 based on at least the specified parameter.

[0058] In Fig. Figure 9 shows a flowchart for a cooling method according to the present disclosure. Accordingly, a cooling method for a gas engine piston 100 for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures is shown. The steps of the cooling method can be carried out using a cooling system 10 according to the present disclosure. For this purpose, the cooling method comprises a piston cooling device 12 configured to spray a cooling oil stream 14 from a first position P1 and / or from at least one second position P2, and a cooling device 16 configured to control the piston cooling device 12 to the first and / or second position P1, P2 based on at least one predetermined parameter.

[0059] The cooling method of a gas engine 100 for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures according to the present disclosure comprises the steps of receiving S10 a predetermined parameter 18 at the control device 16, controlling S20 the piston cooling device 12 to the first and / or second position P1, P2 based on the at least one predetermined parameter 18, such that cooling oil deposits on a gas engine piston surface 140 are burned to ash.

[0060] More specifically, controlling S20 the piston cooling device 12 such that cooling oil deposits on the gas engine piston surface 140 are burned to ash may include adjusting, for example, reducing, a cooling oil flow such that a temperature at the piston surface 140 is maintained that is sufficient to burn cooling oil deposits to ash during combustion.

[0061] According to a preferred embodiment, the gas engine piston surface 140 may be a surface facing the combustion chamber 150.

[0062] It will be apparent to one skilled in the art that these embodiments and subject matter are merely examples of a multitude of possibilities. Therefore, the embodiments shown herein should not be understood as limiting these features and configurations. Any possible combination and configuration of the described features may be chosen within the scope of the invention.

[0063] This applies in particular to the following optional features, which can be combined with some or all of the aforementioned embodiments, elements, and all features in any technically feasible combination. For example, the cooling system may be suitable for more than one gas engine piston. A gas engine piston may be a component of a gas engine powered by a fuel gas. Furthermore, the gas engine piston or the gas engine may be powered by a fuel gas with different hydrogen / hydrocarbon ratios.

[0064] A cooling system for a gas engine piston for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures may be provided, comprising a piston cooling device configured to spray a cooling oil stream from a first position and / or at least one second position, and a control device configured to control the piston cooling device to the first and / or second position based on at least one predetermined parameter.

[0065] In the context of the present disclosure, the term hydrogen may refer to diatomic, homonuclear hydrogen, H2. Similarly, the term hydrocarbon gas may refer to one or more heteronuclear hydrocarbon gases, C n H m , relate.

[0066] In the context of the present disclosure, cooling oil may be an oil extracted from an oil pan of a gas engine, for example, from a region below a crankshaft to which the piston cylinder is attached. The cooling oil stream may be a stream of cooling oil supplied to the gas engine piston via the piston cooling device.

[0067] The piston cooling device may, for example, comprise a cooling oil inlet and be attached to a piston cylinder such that the cooling oil inlet is in fluid communication with a cooling oil supply available on the piston cylinder.

[0068] The control device may be a control unit with an input and an output. Controlling the piston cooling device to the first and / or second position based on at least the specified parameter may be understood as using the specified parameter as an input parameter for the control device. Likewise, any signal output by the control device for controlling the piston cooling device may be understood as an output of the control device. Control of the piston cooling device by the control device may include inputting an output of the control device to the piston cooling device. The piston cooling device may therefore be configured to receive such an input and implement a cooling oil flow from the first and / or second position in accordance with the control input.For this purpose, commercially available switches and / or valves can be used that are suitable for directing, blocking and allowing the flow of cooling oil.

[0069] The specified parameter may be a parameter that is specified prior to operation of the gas engine piston. According to one example, the specified parameter may be a parameter that is specified prior to engine start-up. According to another example, the specified parameter may be a parameter that is specified prior to a fuel gas having a particular hydrogen / hydrocarbon gas ratio entering the gas engine piston. According to another example, the specified parameter may be understood to exclude real-time operating phases of the engine, such as start-up at rated engine operation.

[0070] For the purposes of the present disclosure, controlling or regulating the piston cooling device may refer to a closed-loop control or a closed-loop control. In some cases, the control may also refer only to the (one-time) adjustment of the piston cooling device before or at the start of gas engine piston operation. Adjusting the piston cooling device to the first and / or second position may be performed by setting the specified parameter. The specified parameter may be a function of the cooling oil flow or may comprise a property thereof in explicit or implicit form. The setting of the piston cooling device (first position and / or the at least second position) may be read from a table.

[0071] In a preferred embodiment, the piston cooling device may further comprise means configured to limit and / or exceed a cooling oil flow based on an output of the control device.

[0072] A cooling system comprising such a piston cooling device and a control device configured to control the piston cooling device to the first and / or at least the second position based on at least the specified parameter has the advantage that piston cooling can be avoided depending on gas engine operating phases such as start-up or nominal operation. This allows the cooling system for a gas engine piston to be tailored to the combustion of hydrogen and hydrogen / hydrocarbon gas mixtures. The proposed cooling system can thus be more reliable, more cost-effective, less prone to failure, and easier to maintain.

[0073] According to a further embodiment, the specified parameter can be a function of a fuel gas, a function of a fuel gas concentration, and / or a hydrogen / hydrocarbon gas substitution ratio. This has the advantage that the piston cooling can be tailored to the fuel gas, in particular to fuel gas compositions with different combustion properties and different heat generation properties. In particular, it can be achieved that cooling oil residues are burned to ash during combustion, even when hydrogen is burned in the fuel gas. This prevents the formation of cooling oil coke deposits, which act as glow spots in the subsequent combustion cycle, and thus reduces the risk of spontaneous ignition. Thus, safe and reliable operation of the gas engine can be achieved over a wide range of different fuel gases.

[0074] For example, it is known that the hydrogen concentration in a fuel gas has a significant influence on the heat generation and propagation in a gas engine piston.

[0075] It has been found that an increased hydrogen concentration in a fuel gas can be associated with less heating of the gas engine piston, rather than increased heating of the gas engine piston. Accordingly, an increased hydrogen concentration in a fuel gas can be associated with a lower cooling requirement. With such a control device, it can be achieved that cooling oil residues are burned to ash during combustion. This can prevent the formation of cooling oil coke residues, which act as glow spots, and can prevent glow spot-induced self-ignition. This can improve engine operational reliability and engine performance.

[0076] In a preferred embodiment, the control device can be configured such that the piston cooling device is controlled into the second position when the fuel gas has a high hydrogen concentration, preferably between 100 vol.% and 70 vol.%, wherein preferably the control device is configured such that the piston cooling device is controlled into the first position when the fuel gas has a low hydrogen concentration, preferably between 0 vol.% and 70 vol.%.

[0077] More preferably, the first position may be a position where the cooling performance is high, for example, a position suitable for spraying the cooling oil flow into a cooling oil line of the piston. Furthermore, the second piston may be a position where the cooling performance is lower, for example, a position suitable for spraying the cooling oil flow onto the underside of a piston.

[0078] This can prevent excessive piston cooling when the hydrogen concentration in the fuel gas is high. If a gas engine piston powered by hydrogen or high hydrogen concentrations is cooled in the same way as gas engine pistons powered by hydrocarbon gases, there is a high risk of unburned cooling oil residues causing hot spots on the gas engine piston.

[0079] In a preferred embodiment of the cooling system, the piston cooling device may comprise a first cooling oil nozzle configured to spray the cooling from the first position and a second cooling oil nozzle configured to spray the cooling oil stream from the second position.

[0080] In other words, a separate cooling oil nozzle can be provided for each position. These cooling oil nozzles can be rigidly attached to the piston cooling device. By providing a first cooling oil nozzle and a second cooling oil nozzle in the sense of this embodiment, a repeatable and predictable cooling performance can be achieved by spraying the cooling oil flow from either the first, the second, or both cooling oil nozzles. This can increase the reliability of the cooling system.

[0081] In a preferred embodiment, the first and second cooling oil nozzles can be attached to a first and second arm, respectively, with a first and second cooling oil channel. This allows the positioning of the nozzles on the piston cooling device relative to each other and relative to the gas engine piston to be cooled to be achieved in a simple manner. By providing dedicated cooling oil channels, the piston cooling device can be easily controlled into the first and / or second position by directing a cooling oil flow to one or both dedicated cooling oil channels.

[0082] In a preferred embodiment, the first and second cooling oil nozzles may be offset from one another and / or the first and second cooling oil nozzles may have a different orientation from one another. The offset may be in a plane parallel to the piston bottom. One cooling oil nozzle, e.g., the first cooling oil nozzle, may be aligned below the piston cooling oil line, while the other cooling oil nozzle, e.g., the second cooling oil nozzle, may be aligned below a piston cooling bottom surface. This allows the cooling oil nozzles to be positioned to spray cooling oil onto the assigned target on the gas engine piston. Optionally, such positioning of the cooling oil nozzles may include rearranging them into different orientations to spray cooling oil onto the assigned target on the gas engine piston. Alternatively or additionally, the offset may be in a direction of cooling oil spray.

[0083] According to a further embodiment, the piston cooling device can be configured such that, at a cooling oil pressure of 5 bar or more, the cooling oil flow is directed to the first cooling nozzle. Thus, the cooling oil flow can be sprayed from the first position. Likewise, the cooling oil valve can be configured such that, at a cooling oil pressure below 5 bar, the cooling oil flow is directed to the second cooling nozzle. Thus, the cooling oil flow can be sprayed from the second position.

[0084] According to a further embodiment, the piston cooling device may comprise a cooling oil valve configured to permit or block cooling oil flow in the first cooling oil channel and / or the second cooling oil channel. The cooling oil valve may be a pressure-actuated valve.

[0085] According to another embodiment of the present disclosure, the piston cooling device may comprise a rotatable nozzle configured to be rotatable into the first position and / or the at least second position. In other words, the piston cooling device according to the second embodiment may comprise only a first arm comprising a first cooling oil channel. Due to its rotatable configuration, for example, by a flexible or pivotable arm, the rotatable nozzle can be brought into the first position and the second position.

[0086] The piston cooling device may include a cooling oil valve configured to allow or block a cooling oil flow in the first cooling oil channel. The cooling oil valve may be a pressure-actuated valve. Furthermore, the rotatable nozzle may be configured to be rotatable by pressure. For example, the cooling oil valve may be configured such that at a cooling oil pressure of 5 bar or more, the cooling oil flow is directed into the cooling oil channel and the rotatable nozzle is in the first position. Thus, the cooling oil can be sprayed from the first position. Likewise, the cooling oil valve may be configured such that at a cooling oil pressure below 5 bar, the cooling oil flow is still directed into the cooling oil channel and the rotatable nozzle is in the second position. Thus, the cooling oil can be sprayed from the second position.

[0087] According to a preferred embodiment, the control device can be configured to control the piston cooling device to the first and / or second position based on a gas piston temperature. Two inputs can be provided: the gas piston temperature and the specified parameter. In this way, the piston cooling device can be controlled in a fail-safe manner.

[0088] In a preferred embodiment, the cooling system may further comprise a cooling oil pump configured, when actuated by the control device, to increase or decrease the cooling oil pressure to control the piston cooling device to the first and / or second positions. The cooling oil pump may be configured to use an output of the control device as an input. The cooling oil pump may be actuated by the control device to achieve a desired pressure. Preferably, the cooling oil pump may be calibrated to achieve a desired pressure for a particular output of the control device.

[0089] In this way, a simple, cost-effective, and easy-to-operate and maintain cooling system for gas engine pistons can be provided. Furthermore, a cooling system for a gas engine piston can be provided that can be operated with fuel gases with different hydrogen-to-hydrocarbon gas ratios.

[0090] A gas engine may be provided comprising at least one gas engine piston and a cooling system according to the present disclosure, wherein the gas engine piston is configured to be operable with at least one fuel gas, preferably with at least two fuel gases having different hydrogen-to-hydrocarbon gas ratios, wherein the specified parameter is a function of the fuel gas used. With respect to the cooling system, the above-mentioned explanations, embodiments, advantages, and technical effects may apply accordingly.

[0091] A cooling method for a gas engine piston may be provided, including a cooling system according to the present disclosure, and comprising the steps of receiving a specified parameter at the control device, controlling the cooling oil flow based on at least the specified parameter, such that cooling oil deposits on a gas engine piston surface are burned to ash. With respect to the cooling system, the above explanations, embodiments, advantages, and technical effects may apply accordingly, if appropriate.

[0092] More specifically, controlling the piston cooling device so that cooling oil deposits on the gas engine piston surface are burned to ash may include adjusting, for example, reducing a cooling oil flow so that a temperature at the piston surface is maintained that is sufficient to burn cooling oil deposits to ash during combustion.

[0093] According to a preferred embodiment, the gas engine piston surface 140 may be a surface facing a combustion chamber.

[0094] Such a cooling system can ensure that cooling oil residues are burned to ash during combustion. This prevents the formation of cooling oil coke residues, which act as glow spots, and can prevent glow spot-induced self-ignition. This can improve engine operational reliability and performance.

[0095] In this way, a simple, cost-effective and easy-to-operate and maintain cooling method for a gas engine piston can be provided.

[0096] According to a preferred embodiment, the predetermined parameter may comprise a hydrogen concentration and / or a hydrogen / hydrocarbon gas ratio, wherein the control step further comprises a sub-step for reducing the cooling oil flow for an increased hydrogen concentration and / or an increased hydrogen / hydrocarbon gas ratio and preferably a further step for increasing the cooling oil flow for a reduced hydrogen concentration and / or a reduced hydrogen / hydrocarbon gas ratio. Industrial applicability

[0097] With reference to the figures, a cooling system for a gas engine piston, a gas engine and a cooling method for a gas engine piston are applicable in any suitable internal combustion engine, for example in internal combustion engines for gaseous fuels and in particular in an internal combustion engine operated with fuel gases comprising hydrocarbon / hydrogen gas mixtures.

[0098] In practice, a gas engine piston cooling system, a gas engine piston, and / or any combination of these various assemblies and components may be manufactured, purchased, or sold to retrofit a gas engine or a gas engine already in service in the aftermarket, or alternatively, it may be manufactured, purchased, sold, or otherwise acquired in an OEM (Original Equipment Manufacturer) context.

[0099] As already indicated, the above-mentioned embodiments can provide a simple, cost-effective and reliable cooling system for a gas engine piston.

[0100] Referring to Fig. 1, an embodiment is shown disclosing a cooling system for a gas engine, including a piston cooling device configured to spray a cooling oil stream from a first position and / or at least one second position, and a control device configured to control the piston cooling device to the first and / or second position based on at least the specified parameter. One skilled in the art will expect various embodiments of the present disclosure to exhibit improved simplicity, requiring less maintenance and less complex cooling system tuning technologies.

[0101] The same advantages also apply to the other figures, in particular to the gas engine incorporating such a cooling system and to the cooling method.

[0102] The present description is for illustrative purposes only and should not be construed to limit the breadth of the present disclosure in any way. Therefore, those skilled in the art will appreciate that various modifications may be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features, and advantages will become apparent upon an examination of the accompanying drawings and the appended claims. As used herein, the items "a, an" are intended to include one or more items and may be used interchangeably with "a, an, or more." When only one item is intended, the term "a, an" or similar language is used.Likewise, the terms "comprises," "comprise," "having," "include," "includes," "containing," or the like, as used herein, are intended to be extensible. Furthermore, the term "based on" shall mean "at least in part based on," unless expressly stated otherwise.

[0103] All references to the disclosure or examples thereof are intended to refer to the specific example being discussed at that time and are not intended to imply any limitation on the scope of the disclosure generally. Any language of distinction or disparagement with respect to particular features is intended to indicate a lack of preference for those features, but not to exclude them entirely from the scope of the disclosure, unless otherwise noted.

[0104] The mention of ranges of values ​​herein serves merely as a shorthand for individually referring to each value falling within the range, unless otherwise stated herein, and each value is incorporated into the specification as if individually recited herein.

[0105] Certain steps of each method may be omitted, performed in a different order than expressly mentioned, or, in some cases, performed concurrently or in partial steps. Furthermore, variations or modifications may be made to certain aspects or features of various embodiments to provide further embodiments, and features and aspects of various embodiments may be added to or substituted for other features or aspects of other embodiments to provide still further embodiments.

[0106] Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the appended claims, to the extent permitted by applicable law. Furthermore, any combination of the elements described above, in all possible variations thereof, is included in the disclosure, unless otherwise stated herein or clearly contradicted by context. List of reference symbols: P1 first position P2 second position S10 Step for receiving a specified parameter S20 Step for controlling the piston cooling device 10 Piston cooling system 12 Piston cooling device 13 first cooling nozzle 14 Cooling oil flow 15 second cooling nozzle 16 Control device 17 rotatable nozzle 18 fixed parameters 20 fuel gas 22 Fuel gas concentration 24 Hydrogen concentration 25 Hydrogen / hydrocarbon ratio 26 User input interface 28 Hydrogen sensor 30th issue 32 Cooling oil valve 34 Cooling oil pump 36 first arm 38 second arm 40 first cooling oil channel 42 second cooling oil channel 44 fasteners 100 gas engine pistons 110 Piston oil temperature 120 piston bottom 130 piston oil line 140 piston surface 150 combustion chamber 200 gas engine

Claims

[1] Cooling system (10) for a gas engine piston (100) for the combustion of hydrogen or hydrogen / hydrocarbon gas mixtures, the system comprising: a piston cooling device (12) configured to spray a cooling oil stream (14) from a first position (P1) and / or at least one second position (P2); and a control device (16) configured to control the piston cooling device (12) into the first and / or second position (P1, P2) based on at least one predetermined parameter (18). [2] Cooling system (10) according to claim 1, wherein the first position (P1) is a position suitable for spraying the cooling oil flow (14) into a piston oil line (130), and wherein the second position (P2) is a position suitable for spraying the cooling oil flow (14) onto a piston underside (120). [3] Cooling system (10) according to claim 1 or claim 2, wherein the predetermined parameter (18) is a function of a fuel gas (20). [4] Cooling system (10) according to claim 3, wherein the fixed parameter (18) is a function of a fuel gas concentration (22), a hydrogen concentration (24) and / or a hydrogen / hydrocarbon ratio (25). [5] Cooling system (10) according to one of claims 3 to 4, wherein the control device (16) is configured such that the piston cooling device (12) is controlled into the second position (P2) when the fuel gas (20) has a high hydrogen concentration (24), preferably between 100 vol.% and 70 vol.%, wherein preferably the control device (16) is configured such that the piston cooling device (12) is controlled into the first position (P1) when the fuel gas (20) has a low hydrogen concentration, preferably (24) between 0 vol.% and 70 vol.%. [6] Cooling system (10) according to one of the preceding claims, wherein the piston cooling device (12) comprises a first cooling oil nozzle (13) configured to spray the cooling oil flow (14) from the first position (P1) and a second cooling oil nozzle (15) configured to spray the cooling oil flow (14) from the second position (P2). [7] Cooling system (10) according to claim 6, wherein the first and second cooling oil nozzles (13, 15) are attached to first and second arms (36, 38) respectively, which comprise first and second cooling oil channels (40, 42). [8] Cooling system (10) according to claims 6 to 7, wherein the first and second cooling oil nozzles (13, 15) are offset from one another and / or wherein the first and second cooling oil nozzles (13, 15) have different orientations with respect to one another. [9] Cooling system (10) according to one of claims 1 to 5, wherein the piston cooling device (12) comprises a rotatable (3D) nozzle (17) configured to be rotatable into the first position (P1) and / or the at least second position (P2). [10] Cooling system (10) according to claim 9, wherein the control device (16) is configured to further control the piston cooling device (12) to the first and / or second position (P1, P2) based on a gas piston temperature (110). [11] Cooling system (10) according to any one of the preceding claims, further comprising a user input interface (26) configured to provide the specified parameter (18). [12] Cooling system (10) according to one of the preceding claims, wherein the control device further comprises a lookup table, correlation and / or algorithm configured to provide an output (30) for selecting the first and / or second position (P1, P2), preferably wherein the output (30) is a function of a cooling oil pressure. [13] Cooling system (10) according to one of the preceding claims, further comprising a cooling oil pump (34) configured to increase or decrease cooling oil pressure upon actuation by the control device (16) to control the piston cooling device (12) to the first and / or second position (P1, P2). [14] Gas engine (200) for the combustion of hydrogen or hydrogen / hydrocarbon gas mixtures, comprising at least one gas engine piston (12) and a cooling system (10) according to one of the preceding claims. [15] Cooling method for a gas engine piston (100) for combustion of hydrogen or hydrogen / hydrocarbon gas mixtures, comprising a piston cooling device (12) configured to spray a cooling oil stream (14) from a first position (P1) and / or at least one second position (P2), and a control device (16) configured to control the piston cooling device (12) to the first and / or second position (P1, P2), comprising the following steps: - receiving (S10) a specified parameter (18) at the control device (16); - controlling (S20) the piston cooling device (12) into the first and / or second position (P1, P2) based on at least the specified parameter (18) so that cooling oil deposits on a gas engine piston surface (140) are burned to ash.

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