split-cycle engine

Abstract

A split-cycle internal combustion engine comprising a compression cylinder housing a compression piston; and a combustion cylinder housing a combustion piston; a crossover passage between the compression cylinder and the combustion cylinder arranged to provide working fluid to the combustion cylinder; a reactivity adjuster operable to adjust the reactivity of a fuel used in combustion; and a controller arranged to receive an indication of at least one of (i) the pressure of the working fluid, (ii) the temperature of the working fluid, (iii) the combustion generated NOx, and (iv) the extent of engine knock in the combustion cylinder; wherein the controller is configured to operate the reactivity adjuster to adjust the reactivity of the fuel based on the received indication. This can improve efficiency as a greater proportion of the fuel can be combusted.

Description

[0001] Related applications

[0002] This application is a divisional application of Chinese application No. 201880048263.6, entitled "Split-cycle engine", which was filed on July 20, 2018 and claimed priority date from the GB Patent Office, which filed on July 27, 2017. Technical Field

[0003] This invention relates to a split-cycle internal combustion engine and its operating method. Background Technology

[0004] Conventional internal combustion engines operate based on the Otto and Diesel cycles. This cycle is fundamentally linked to a close relationship between improved efficiency (and consequently performance) and the generation of NOx, particulate matter, and carbon dioxide emissions. With increasing concerns about air pollution and global warming, modern regulations concerning such emissions are becoming increasingly stringent. A review of this engine cycle reveals that increased cycle efficiency leads to higher temperatures, which in turn leads to increased NOx formation at that efficiency level and limitations on material properties. To mitigate NOx formation, the necessity has been identified for introducing additional equipment complexity in the form of exhaust aftertreatment.

[0005] For both the Otto and Diesel cycles, efficiency is based on the pressure at the end of compression. The Diesel cycle efficiency also depends on the combustion rate, as engine speed and combustion rate affect the volume ratio between the start and end of combustion. Improving the efficiency of modern engines is therefore also limited by the practicalities of materials. This is because the peak temperatures and pressures associated with engines can reach very high levels.

[0006] NOx compounds form when the temperature of the air-fuel mixture rises above 2100 K. This could occur, for example, in localized "hot spots" or over a wider area, such as throughout an engine cylinder. NOx compounds are linked to respiratory health problems in humans; therefore, the production of these compounds and their emission into the atmosphere pose significant health risks. Furthermore, the formation of these compounds is endothermic, making them inherently useless for maximizing the conversion of chemical energy into work.

[0007] UK patent applications Nos. 1622114.5, 1706792.7 and 1709012.7 disclose a split-cycle internal combustion engine that uses coolant injectors for cryogenic fluids (fluids that have been condensed into their liquid phase by a refrigeration process). Summary of the Invention

[0008] The various aspects of the invention are as described in the independent claims, while optional features are as described in the dependent claims. The various aspects of the invention may be provided in combination with each other, and a feature of one aspect may be applied to other aspects. Attached Figure Description

[0009] Various aspects of this disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0010] Figure 1 A schematic diagram of an exemplary split-cycle internal combustion engine device is shown.

[0011] Figure 2 A schematic diagram of an exemplary split-cycle internal combustion engine device is shown.

[0012] Figure 3 A temperature-entropy plot is shown for the operation of an exemplary split-cycle internal combustion engine.

[0013] Figure 4 It shows Figure 3 The temperature-entropy line graph is shown, and the constant pressure line is also shown on the graph.

[0014] Figure 5 A graph is shown illustrating an exemplary scenario using a split-cycle internal combustion engine based on equivalence ratio, onset temperature, and end temperature.

[0015] Figure 6 A flowchart is shown illustrating an exemplary method of operation for a split-cycle internal combustion engine.

[0016] Figure 7 A flowchart is shown illustrating an exemplary method of operation for a split-cycle internal combustion engine.

[0017] Figure 8 A flowchart is shown illustrating an exemplary method of operation for a split-cycle internal combustion engine.

[0018] Figure 9 A flowchart is shown illustrating an exemplary method of operation for a split-cycle internal combustion engine.

[0019] Figure 10A flowchart is shown illustrating an exemplary method of operation for a split-cycle internal combustion engine.

[0020] Figure 11 A flowchart is shown illustrating an exemplary method of operation for a split-cycle internal combustion engine.

[0021] Figure 12 A flowchart is shown illustrating an exemplary method of operation for a split-cycle internal combustion engine. Detailed Implementation

[0022] In one example, a split-cycle internal combustion engine is disclosed, including a controller configured to control a coolant system such that the peak combustion temperature in the combustion cylinder is below a selected threshold. The controller can control the peak combustion temperature to suppress NO during combustion. X The generation of particles has significant environmental benefits because these chemicals are known to be harmful to human health.

[0023] In one example, a split-cycle internal combustion engine is disclosed, including a controller configured to control the opening and closing of an intake valve to control the flow of working fluid into the combustion cylinder. The controller can control the intake valve to open and close at selected times to control the peak combustion temperature, thereby suppressing NO during combustion. X The generation of particles has significant environmental benefits because these chemicals are known to be harmful to human health.

[0024] In one example, a split-cycle internal combustion engine is disclosed, including a controller configured to control a reactivity regulator to adjust fuel reactivity based on received engine operating condition indications. When fuel reactivity is low, the controller can control the reactivity regulator to increase fuel reactivity. This enables improved efficiency because a larger proportion of fuel combustion can be achieved.

[0025] In one example, a split-cycle internal combustion engine is disclosed, including a controller configured to control the injection timing of fuel injectors injecting fuel into the combustion cylinder. The controller can control the timing of the injectors to control the peak combustion temperature in the combustion cylinder. This allows the controller to suppress NO generated during combustion. x And particles, because lower peak temperatures can be achieved. This has significant environmental benefits, as these chemicals are known to be harmful to human health.

[0026] In one example, a split-cycle internal combustion engine is disclosed, including a controller configured to control a coolant system based on an estimate of the peak combustion temperature, thereby maintaining the peak combustion temperature within a selected range. This allows the controller to prevent the engine from releasing NO during combustion at sufficiently high operating temperatures. x And particulate matter, and it can prevent the engine from operating at sufficiently low temperatures that would negatively impact engine performance. In one example, a split-cycle internal combustion engine is disclosed, which includes a controller configured to control the coolant system such that the working fluid in the bridging channel flows into the combustion cylinder at a rate greater than a velocity threshold. This enables better mixing of the fuel and working fluid before combustion. This may reduce the fuel richness, thus providing a leaner air-fuel mixture, allowing for more complete combustion and suppressing the formation of particulates such as soot. It can also reduce the occurrence of any “hot spots” where combustion occurs at higher peak temperatures, which produce NOx or other undesirable pollutants.

[0027] In one example, a split-cycle internal combustion engine is disclosed, including a controller configured to control a cross-sectional area defined by an intake valve leading to a combustion cylinder, such that working fluid flows into the combustion cylinder at a velocity greater than a velocity threshold. This allows for better mixing of the fuel and working fluid before combustion. This can reduce fuel richness and reduce any NO production. x Or, particle "hot spots" may appear.

[0028] Figure 1A first example of a split-cycle internal combustion engine 100 is shown, which is arranged to control the peak combustion temperature below a selected threshold. The engine 100 is arranged to provide an indication of the peak combustion temperature to a controller 60, which determines the peak combustion temperature based on this indication. Based on the determined peak combustion temperature, the controller 60 controls the coolant system to regulate the temperature of the working fluid supplied to the combustion cylinder 20 of the engine 100. Specifically, the coolant system can be arranged to control this temperature such that the working fluid in the bridging passage 30 between the compression cylinder 10 and the combustion cylinder 20 of the engine 100 is sufficiently cold, such that when the working fluid is used in the combustion cylinder 20, the peak combustion temperature does not exceed the selected threshold as part of the combustion process. The controller 60 can operate based on a feedback loop that controls the operation of the coolant system, thereby controlling the temperature of the working fluid to be supplied to the combustion cylinder 20 within a selected range. This allows for control of the peak combustion temperature, thereby suppressing the formation of compounds such as NOx. The feedback loop can also be based on a cooling threshold, where, in response to the controller determining that the peak combustion temperature is below the cooling threshold, the controller controls the coolant system to adjust the temperature of the working fluid, thereby causing the peak combustion temperature of the coolant to exceed the cooling threshold. This allows the controller to control the engine to operate within a selected peak temperature range. (See figure.) Figure 1 A split-cycle internal combustion engine 100 is shown, comprising a compression cylinder 10 and a combustion cylinder 20. The compression cylinder 10 houses a compression piston 12, which is connected via a connecting rod 52 to a corresponding crank on a portion of a crankshaft 70. The combustion cylinder 20 houses a combustion piston 22, which is connected via a connecting rod 54 to a corresponding crank on a portion of the crankshaft 70. The compression cylinder 10 is connected to the combustion cylinder 20 via a bridging passage 30. The bridging passage 30 may include a co-current heat exchanger for heat transfer. The compression cylinder 10 includes an inlet port 8 for receiving fluid from outside the engine 100 and an outlet port 9 connected to the bridging passage 30. The outlet port 9 includes a valve, such as a check valve, to prevent compressed fluid from flowing back into the compression cylinder 10. The combustion cylinder 20 includes an intake valve 18 also connected to the bridging passage 30 and an exhaust valve 19 for transferring exhaust gas from the combustion cylinder 20 to the combustion cylinder 20. These clutches provide a fluid flow path between the compression cylinder 10 and the combustion cylinder 20 via a bridging channel 30. The engine 100 also includes a coolant system. The coolant system is shown as including a liquid coolant reservoir 40 connected to the compression cylinder 10 via a coolant injector 14 defining a liquid flow path. The coolant system may also include injectors for injecting coolant into the bridging channel 30, although... Figure 1Not shown. The coolant system may also include heat transfer via a co-current heat exchanger. For example, this may include using heat from exhaust gas from the combustion cylinders to heat the co-current heat exchanger. It may include using the co-current heat exchanger to transfer heat from the split-cycle internal combustion engine 100. The engine 100 also includes a fuel reservoir 80 connected to the combustion cylinders 20 via fuel injectors 82, thereby defining a fluid flow path between the fuel reservoir 80 and the combustion cylinders 20. The engine 100 includes a controller 60 and a plurality of sensors, which are illustrated as black dots connected to the controller 60. However, it should be understood that the sensors shown are merely exemplary and there may be a different number of sensors, or they may be placed in different locations. For example, the inlet port 8 may also include a temperature sensor. The sensors may be connected to the controller 60 via physical wires or wirelessly. Figure 1 In the example shown, a compression sensor 11 is located within the compression cylinder 10. The compression sensor 11 may be mounted, for example, adjacent to the inlet port 8 or adjacent to the coolant injector 14. The compression sensor 11 may include a temperature sensor. Figure 1 The exemplary engine 100 shown also includes a combustion sensor 21 within the combustion cylinder 20. The compression sensor 21 may include a temperature sensor; it may also include a pressure sensor. A bridging sensor 31 within a bridging passage 30 is also shown. The bridging sensor 31 may include a temperature sensor; it may also include a pressure sensor. Additionally, the engine 100 includes a crankshaft sensor 71 mounted to a crankshaft 70. The crankshaft sensor can provide an indication of torque demand from the engine. An exhaust sensor 91 downstream of the exhaust valve 19 in the combustion cylinder 20 is also shown. The exhaust sensor 91 may include a temperature sensor; it may include a pressure sensor; it may include an oxygen content sensor configured to provide NO in the engine exhaust. x Concentration indication. In some examples, the liquid coolant reservoir 40 may also include sensors, for example, for measuring the amount, such as mass, of liquid contained in the reservoir 40. The controller 60 is also connected to the coolant injector 14, the fuel injector 82, and / or the reservoir 80.

[0029] The sensor is configured to send at least one signal to the controller 60, providing an indication of at least one parameter associated with the engine 100. The parameters of the engine 100 may include the temperature of the working fluid in the engine (at various locations, such as exhaust, compression cylinder 10, bridging passage 30, etc.). It may include the pressure of the working fluid in the engine; it may include the demand on the engine; it may include NO in the engine. xThe generated values ​​may include the timing of the opening and closing of the intake valve 18; they may include the timing of fuel injection into the combustion cylinder. Parameters of engine 100 may include an indication of engine knock, for example, based on received audible signals from engine operation. Engine knock can occur when fuel is not ignited at the correct time during piston circulation and can be detected by listening to engine noise; therefore, an indication of engine knock can be considered a parameter of the engine.

[0030] For example, in Figure 1 In the example shown, compression sensor 11 is configured to measure at least one parameter associated with compression cylinder 10. Combustion sensor 21 is configured to measure at least one parameter associated with combustion cylinder 20. Bridging sensor 31 is configured to measure at least one parameter associated with bridging channel 30. Additionally, crank sensor 71 is configured to measure the engine speed (RPM) of engine 100, and exhaust sensor 91 is configured to measure at least one parameter of the exhaust gas discharged through exhaust valve 19 of combustion cylinder 20. This measurement of at least one parameter provides an indication of the peak combustion temperature in combustion cylinder 20. Each sensor can provide the indication of the peak temperature to controller 60, such that controller 60 determines the peak combustion temperature in combustion cylinder 20.

[0031] Engine 100 is arranged such that air is drawn into compression cylinder 10 through inlet port 8. Compression piston 12 is arranged to compress this air, and during the compression phase, liquid coolant can be added to compression cylinder 10. Bridging passage 30 is arranged to receive working fluid via outlet port 9 and deliver it to combustion cylinder 20 via intake valve 18. Engine 100 is also arranged to add fuel from fuel reservoir 80 to the working fluid in combustion cylinder 20 via fuel injector 82, and the mixture of fuel and working fluid (e.g., by operation of an ignition source, not shown) extracts useful work by rotating crankshaft 70.

[0032] Fuel reservoir 80 is connected to controller 60, such that controller 60 controls the delivery of fuel to combustion cylinder 20. In some examples, controller 60 is configured to determine the amount of fuel to be injected based on an indication received from at least one parameter of engine 100. For example, controller 60 may be configured to obtain an indication of at least one parameter via a signal indicating peak combustion temperature received from exhaust sensor 91 or a signal indicating engine demand received from crank sensor 71.

[0033] During operation, controller 60 is configured to receive an indication of the peak combustion temperature. Figure 1At least one sensor shown receives a signal. For example, controller 60 may receive an indication of the temperature in the exhaust gas from exhaust sensor 91. When the controller receives an indication from a sensor that does not directly measure the peak combustion temperature, the controller determines an estimate of the peak combustion temperature in combustion cylinder 20 based on the received indication. For example, the received indication of the temperature in the exhaust gas can be used to infer the peak combustion temperature in the combustion cylinder. When the controller receives an indication from a sensor that directly measures the peak combustion temperature, such as combustion sensor 20, the controller can use the indication of the peak temperature instead of determining the peak temperature separately.

[0034] The peak combustion temperature typically occurs at the end of the piston 22's motion from top dead center (TDC) to bottom dead center ("BDC"). When the controller 60 receives an indication from a sensor that cannot directly measure this peak temperature (e.g., not in the combustion cylinder 20), the controller 60 is configured to determine an estimate of the peak temperature based on the received indication. This may include using a mathematical model that estimates the peak combustion temperature based on engine parameter values ​​(e.g., the temperature of the working fluid in the bridging passage). For example, such a model may include determining values ​​based on prior data used to generate heat throughout the engine cycle and / or dissipate heat and subsequently cool after combustion has occurred. Sensors may measure system and / or working fluid parameters (e.g., temperature, pressure), and this may be an indication provided to the controller 60. Based on this indication, the controller 60 can determine an estimate of the peak temperature in the combustion cylinder 20 using known thermodynamic relationships. For example, based on the received indication of the working fluid's pressure and temperature, the working fluid's density can be determined (e.g., based on an equation of state that relates pressure, temperature, and density).

[0035] In one example, controller 60 may receive an indication of the combustion peak temperature from a sensor that measures parameters of the working fluid after combustion. For example, this measurement may be performed by exhaust sensor 91. Exhaust sensor 91 can be configured to measure the temperature of the working fluid in the exhaust. The post-combustion temperature provides an indication of the combustion peak temperature. An estimate of the combustion peak temperature can be determined based on the post-combustion temperature using prior data, such as a lookup table. It should be understood that this provides a good approximation of the peak temperature of the working fluid during combustion, since the time it takes for the working fluid to flow from combustion cylinder 20 through exhaust valve 19 is very short after the time it takes to reach the combustion peak temperature. Therefore, exhaust sensor 91 can measure the post-combustion temperature and, based on this measurement, provide an indication of the combustion peak temperature to controller 60. Controller 60 then determines the combustion peak temperature based on the post-combustion temperature. The combustion peak temperature is greater than the post-combustion temperature. The combustion peak temperature can be determined using a lookup table that includes a mapping between the values ​​of the post-combustion temperature and the corresponding values ​​of the combustion peak temperature.

[0036] In another example, controller 60 may receive an indication of the peak combustion temperature from a sensor that measures parameters of the working fluid prior to combustion. This measurement could be performed by a supply sensor, which can be any sensor that provides an indication of engine or working fluid parameters prior to combustion; for example, this indication could come from compression sensor 11 or bridging sensor 31. Bridging sensor 31 can be configured to measure the temperature of the working fluid in bridging channel 30 before it flows into combustion cylinder 20. Therefore, bridging sensor 31 can measure the temperature of the working fluid prior to combustion and provide this indication to controller 60. Controller 60 then determines an estimate of the peak combustion temperature in combustion cylinder 20 based on the pre-combustion temperature. The pre-combustion temperature is lower than the peak combustion temperature. Controller 60 can use a lookup table to determine the estimated peak combustion temperature, which includes a mapping between pre-combustion temperature values ​​and corresponding peak combustion temperature values. The values ​​in the mapping can be determined using a mathematical model that models the thermodynamics of the system to predict the temperature. These can include values ​​determined empirically.

[0037] It should be understood that the lookup table used in any example may also include other parameters. The lookup table thus enables the controller 60 to determine an estimate of the peak combustion temperature based on the current condition of the engine 100 and the temperature of the working fluid (e.g., pre-combustion or post-combustion temperature). For example, one of the other parameters may include an indication of the demand on the engine 100, which may be determined based on a signal received from the crank sensor 71. One parameter may include a timer indicating the duration the engine 100 has been running. This can provide an indication of the engine temperature, since the operating temperature will be lower during engine start-up as the engine warms up. Therefore, the time the engine has been running can provide an indication of the likely temperature of the engine itself. One parameter may include an indication of the overall temperature of the engine 100. It should be understood that other parameters may include any suitable parameters that can affect the determination of the peak combustion temperature in the combustion cylinder 20. For example, during engine start-up, the combustion cylinder 20 may be colder than during normal operation, so the temperature increase of the working fluid between the pre-combustion temperature and the peak combustion temperature may be less than that of the combustion cylinder 20 after prolonged use, or under higher demand. Based on the temperature indication of engine 100 (e.g., combustion cylinder 20), or for example based on a timer indicating how long engine 100 has been running, a mapping from pre-combustion temperature to peak combustion temperature can provide a more accurate estimate of the peak combustion temperature in combustion cylinder 20.

[0038] Controller 60 is configured to control the coolant system to cool the working fluid in response to determining that the temperature of the working fluid is greater than a selected threshold. During engine 100 startup, engine 100 will operate at a lower temperature, so controller 60 can determine that the estimated peak combustion temperature is significantly lower than the selected threshold. In this case, controller 60 can control the coolant system such that little or no cooling occurs. Once engine 100 has progressed from the startup state to normal operating mode, controller 60 is configured to determine the peak combustion temperature and control the coolant system to regulate the temperature of the working fluid. Controlling the coolant system is based on a feedback loop that includes programmed monitoring of the peak combustion temperature and control of the cooling of the working fluid such that the peak combustion temperature does not exceed the selected threshold. In response to determining that the peak combustion temperature exceeds the selected threshold, controller 60 is configured to operate the coolant system to increase the cooling of the working fluid. Figure 1In the example shown, this involves controlling the coolant injector 14 to inject more coolant into the compression cylinder 10. However, it should be understood that other methods can be used to control the temperature of the working fluid (e.g., through heat transfer using a co-current heat exchanger). As the working fluid in the compression cylinder 10 is compressed, some of the increased heat in the working fluid can be absorbed by the injected coolant. The coolant will absorb some of the heat to overcome its latent heat of vaporization, which will help to suppress the temperature rise in the combustion cylinder 20. Therefore, by controlling the amount of coolant injected into the combustion cylinder 20, the controller 60 can control the heat of the working fluid. In particular, the controller 60 can influence the heat of the working fluid before it flows into the combustion cylinder 20 in the bridging channel 30.

[0039] The selected threshold includes a criterion for peak combustion temperature. The controller can determine whether the criterion is met based on a comparison including an estimated peak combustion temperature and the criterion. The selected threshold can be a value of a maximum temperature such that any peak combustion temperature above that maximum temperature does not meet the criterion. The value of the selected threshold can be selected to suppress the formation of NOx compounds. The controller can compare the value of the peak combustion temperature with the selected threshold, where the comparison is based on the average of the peak combustion temperatures, i.e., the "global" value of the peak temperature across the entire cylinder. In other examples, the controller can compare the value of the peak combustion temperature with the selected threshold, where the comparison is based on local peaks of the peak combustion temperature. Local peaks can include the value of the highest peak combustion temperature in any region of the combustion cylinder 20. In some examples, the selected threshold can include an indication of the values ​​of both. The selected threshold may require a temperature equal to or less than 2200 Kelvin; it may require a temperature less than 2150 Kelvin; it may require a temperature less than 2125 Kelvin; it may require a temperature less than 2100 Kelvin; it may require a temperature less than 2075 Kelvin; it may require a temperature less than 2050 Kelvin; it may require a temperature less than 2000 Kelvin; it may require a temperature less than 1900 Kelvin. It should be understood that this value can vary depending on the equivalence ratio of the working fluid and fuel mixture.

[0040] In response to determining that the peak combustion temperature is greater than a selected threshold, controller 60 controls the coolant system to regulate the temperature of the working fluid to be supplied to the combustion cylinder 20. Temperature regulation is achieved using the coolant system as described above. In one example, this can be achieved by increasing the amount of coolant injected into the compression cylinder 10, but alternatively or separately, it can be achieved by controlling heat transfer from the co-current heat exchanger in the bridging channel. Controller 60 can be configured to determine the degree of cooling based on an indication of the determined peak combustion temperature. The coolant system can operate continuously such that the amount of coolant injected is proportional to the amount of cooling required to cool the working fluid to below a selected threshold. It can also operate discretely such that a first volume of coolant is injected above a first selected threshold, and a second volume of coolant is injected above a second selected threshold. Multiple such thresholds may exist.

[0041] By controlling the coolant system to regulate the peak combustion temperature in the combustion cylinder 20, the controller 60 can thus control the split-cycle internal combustion engine 100 to keep the combustion process at a lower temperature to reduce the formation of NOx compounds.

[0042] It should be understood that although the controller has been described as controlling the coolant system to inject more coolant, the same result can be achieved in other ways. For example, this can be achieved by injecting different types of coolant or coolant at different temperatures. Additionally, it should be understood that the sensor is configured to provide the controller 60 with an indication of the combustion peak temperature. However, this indication does not necessarily include temperature; it can include measurements of any suitable thermodynamic parameter from which the combustion peak temperature can be determined. For example, using known thermodynamic relationships, the temperature value can be determined based on a pressure value. On the other hand, Figure 1The operation of the split-cycle internal combustion engine 100 can be achieved by using the timing of the intake valve 18 to regulate the temperature of the working fluid in the combustion cylinder 20. The intake valve 18 is operable to move from a closed state in a first position to an open state in a second position during the piston cycle. When the intake valve 18 is open, the working fluid in the bridging passage 30 can flow into the combustion cylinder 20, while when the intake valve 18 is closed, the working fluid may not enter. In operation, the controller 60 can select the first and second positions based on selected thresholds and / or cooling thresholds. These two positions can be selected such that they are separated by a selected time period; this time period can be constant and / or variable. During the cycle, combustion in the combustion cylinder 20 typically occurs at or very close to the piston's TDC position. Therefore, selecting the first position before TDC allows the working fluid in the bridging passage 30 time to flow into the combustion cylinder 20 before combustion occurs. The second position can be selected at or before TDC, allowing combustion to provide greater force on the piston. This is because the working fluid expands during combustion, causing the combustion piston 22 to move toward its BDC position. If the intake valve remains open during combustion, some of the working fluid may shift back into the bridging channel instead of exerting force on the combustion piston 22. Therefore, if the second position is selected, thus closing the intake valve before the working fluid expands, a greater force will be transmitted to the combustion piston 22.

[0043] Because the first position is before TDC, the working fluid in combustion cylinder 20 will undergo some compression before combustion occurs. This will increase the temperature of the working fluid. The temperature of the working fluid before combustion will affect the peak combustion temperature in combustion cylinder 20, and therefore, by controlling the heat rise caused by this compression in combustion cylinder 20, controller 60 can regulate the peak combustion temperature in combustion cylinder 20. The amount of heat rise caused by compression in combustion cylinder 20 will depend on the first position. The earlier the first position is after BDC, the greater the heat of the working fluid. Therefore, controller 60 can select the first position based on a determined desired heat. This can be determined based on the determined peak combustion temperature in combustion cylinder 20, and therefore the desired additional heat, which is to bring the working fluid to a selected temperature before combustion, thereby ensuring that the peak combustion temperature is within a selected range.

[0044] For example, in response to determining that the estimated peak combustion temperature is greater than a selected threshold, controller 60 selects a first position later during piston cycle. In response to determining that the peak combustion temperature is lower than a cooling threshold, controller 60 selects the first position earlier during piston cycle, allowing the working fluid to receive more heat. Similarly, controller 60 can control a second position based on the peak combustion temperature, cooling, and the selected threshold. On the other hand, Figure 1 The operation of the split-cycle internal combustion engine 100 can regulate the temperature of the working fluid in the combustion cylinder 20 by timing the injection of fuel using the fuel injector 82. Fuel injection can occur at an injection position during the piston cycle. The injection may occur for a preset time period; it may occur within a variable time period; this time period may be based on the amount of fuel to be injected. The controller 60 is configured to select the injection position based on a determined estimate of the peak combustion temperature. For example, in response to determining that the estimated peak combustion temperature is greater than a selected threshold, the controller 60 can control the fuel injector 82 to inject fuel at a delayed injection position during the piston cycle. The delayed injection position may include a position occurring later than the current injection position during the piston cycle. In response to determining that the estimated peak combustion temperature is less than a cooling threshold, the controller 60 can control the fuel injector 82 to inject fuel at an earlier injection position during the piston cycle. The earlier injection position may include a position occurring before the current injection position during the piston cycle.

[0045] Typically, combustion occurs at or shortly after the TDC position of the combustion piston 22. Controlling combustion at the TDC position allows the expansion force to be applied to the combustion piston 22 for a longer period, while the combustion piston 22 returns to its BDC position. The volume in the combustion cylinder 20, defined by the position of the combustion piston 22, changes during the piston stroke and will be lowest at the TDC position of the combustion piston 22. Combustion at the TDC position during the piston cycle results in greater expansion of the working fluid than combustion at a later position. Combustion closer to the TDC can also result in a larger temperature change from the initial temperature compared to combustion later after the TDC. As a result, for earlier-starting combustion, the peak combustion temperature in the combustion cylinder 20 may be higher. There will be no combustion without fuel.

[0046] The controller 60 is configured to control the fuel injector 82 during piston cycle to inject fuel into the combustion cylinder 20 at the injection position. The controller can delay fuel injection, causing fuel to be injected at a later position during piston cycle (e.g., after TDC). Based on a determined estimate of the peak combustion temperature in the combustion cylinder 20, the controller can determine that the estimated peak temperature is too high and may lead to NOx formation. As a way to regulate the temperature in the combustion cylinder 20, the controller can delay fuel injection, thereby causing combustion to occur at a later position during piston cycle. Therefore, the peak combustion temperature can be reduced, which may suppress NOx formation.

[0047] On the other hand, Figure 1The operation of the split-cycle internal combustion engine 100 can be based on an estimated peak combustion temperature in the combustion cylinder 20, using a controller 60 to control the coolant system to regulate the peak temperature of the working fluid supplied to the combustion cylinder 20. The controller 60 can use this estimate to ensure that the peak combustion temperature in the combustion cylinder 20 is within a selected range. Specifically, during normal operation of the engine 100, the controller can select a range such that the peak combustion temperature in the combustion cylinder is not greater than a selected threshold and / or not less than a cooling threshold. The selected range can be chosen as a range of values ​​between the cooling threshold and the selected threshold. This allows the controller 60 to control the engine operation so that both efficiency and NOx generation meet selected evaluation criteria.

[0048] The controller 60 can determine an estimate of the peak combustion temperature based on received indications of engine parameters. For example, the controller 60 can determine the estimate based on received indications of engine demand. In this case, the controller 60 can predict an estimate of the peak combustion temperature to be reached in the combustion cylinder 20 based on the indications of engine demand and (e.g., the indication of the temperature of the working fluid to be supplied to the combustion cylinder 20).

[0049] The prediction can be based on prior data associated with engine 100. For example, controller 60 can access a lookup table that includes a mapping between at least one engine parameter of one or more values ​​and a corresponding estimated peak temperature. Controller 60 may include a machine learning component that includes a model for predicting the peak combustion temperature based on engine-related input data (e.g., engine parameters or measurement records of the engine since it began operating). This machine learning component can be "trained" on data of known peak combustion temperatures associated with the input data. This allows the predictive model of the machine learning component to learn and update based on the training data, thereby providing a more reliable and accurate system for predicting peak temperatures. Based on this estimate, the controller can control the coolant system such that the peak combustion temperature in combustion cylinder 20 is within a selected range. According to the example above, Figure 1 The split-cycle internal combustion engine 100 can regulate the temperature of the working fluid. Temperature regulation can be based on a combination of the examples above.

[0050] Figure 2 A second example of a split-cycle internal combustion engine 100 is shown, which is arranged to control the peak combustion temperature so that it is below a selected threshold. Figure 2 The engine 100 is similar to Figure 1 The engine 100, therefore, components that perform essentially the same functions are given the same reference numerals and will not be described again.

[0051] Figure 2The split-cycle internal combustion engine 100 also includes a reactivity regulator 85. The reactivity regulator 85 is connected to a controller 60, such that the controller 60 controls the operation of the reactivity regulator 85. The reactivity regulator 85 is operable to adjust the reactivity of the fuel used during combustion. The reactivity regulator 85 is shown operable to act on fuel (e.g., in a fuel reservoir 80) to be injected into the combustion cylinder 20. The reactivity regulator 85 is also shown operable to act directly on the fuel within the combustion cylinder 20. The reactivity regulator 85 is operable to increase the fuel's ignition capability. This may include at least one of: making the fuel more reactive, and providing additional means for igniting the fuel in the combustion cylinder 20. The controller 60 may also control the operation of the reactivity regulator 85 in response to determining that the reactivity of the fuel is greater than an overreactivity threshold. This may help reduce NOx formation, as overreactive fuel may produce higher peak combustion temperatures.

[0052] In the example shown, the reactivity regulator 85 includes a system for directing electromagnetic radiation, such as laser or microwave radiation, to the fuel, thereby providing an additional ignition source for the fuel in the combustion cylinder 20. This can provide a more targeted ignition mechanism, thus allowing the fuel to ignite under less favorable ignition conditions, such as when the combustion cylinder 20 is colder than the ignition threshold temperature. The controller 60 can be configured to control the reactivity regulator 85 such that, in response to determining that the temperature in the combustion cylinder 20 and / or the temperature of the working fluid is less than the ignition threshold, the controller 60 controls the reactivity regulator 85 to provide an additional fuel ignition source. The reactivity regulator 85 may include a system for selective energy transfer. The system for selective energy transfer can provide targeted radiation for certain compounds found in the fuel-working fluid mixture to improve the reaction rate. This can include targeted radiation for decomposing compounds that will produce improved combustion, such as decomposing CH4 (methane), thereby allowing combustion to occur at a lower onset temperature, and thus the combustion peak temperature to occur at a lower temperature, which in turn may suppress NOx formation.

[0053] In some examples, the reactivity regulator 85 may include a system for supplying an oxidant or free radical to the fuel. This supply may be in the combustion cylinder 20; it may be in the fuel reservoir 80 (e.g., before fuel is injected into the combustion cylinder 20). The supplied oxidant may ignite a larger proportion of the fuel, potentially increasing the likelihood of initial fuel ignition. Suitable oxidants may include, for example, oxygen or ozone. Although it is understood that any suitable oxidant may be added. The controller 60 is configured to receive an indication of at least one of the pressure, density, and temperature of the working fluid and, based thereon, determine ignition parameters for the working fluid. The determined ignition parameters may provide an indication of the fuel's ignition capability. For example, the ignition parameters may provide an indication of the expected proportion of fuel to be ignited. The controller 60 is configured to determine the ignition parameters based on the received indication. For example, this may include using a lookup table to identify values ​​for the ignition parameters based on one or more values ​​of the thermodynamic properties of the working fluid. These values ​​may be determined theoretically and / or empirically. For example, controller 60 can identify that fuel is unlikely to ignite when it is cold, and therefore, in response to receiving an indication that the working fluid temperature is cold, it can determine the ignition parameters to be low.

[0054] In response to determining that the ignition parameters are below the ignition threshold, controller 60 is configured to operate reactivity regulator 85. Operation of reactivity regulator 85 helps to increase the value of the ignition parameters and thus increases the likelihood of fuel ignition. Controller 60 can be configured to determine the degree of operation of reactivity regulator 85 based on the determined ignition parameters. For example, the degree of operation of reactivity regulator 85 can be determined based on the magnitude of the difference between the ignition parameters and the ignition threshold. Multiple ignition thresholds may exist, and controller 60 can determine the degree of operation of reactivity regulator 85 based on which threshold the ignition parameters satisfy. Reactivity regulator 85 can provide benefits particularly during engine 100 start-up, when the ignition parameters can be below, or even very below, the ignition threshold. For example, the temperature of combustion cylinder 20 may be very low, and operation of reactivity regulator 85 can ignite the fuel, causing combustion to occur at a much lower temperature. Figure 3 It shows the use of Figure 1 and Figure 2The diagram illustrates an exemplary temperature-entropy curve for the operation of a split-cycle internal combustion engine. Dashed lines represent the cycle of an uncooled engine, and solid lines represent the cycle of a cooled engine. This graph is based on approximations of an engine using a pure nitrogen cycle. Both cycles produce the same amount of heat output. Compared to the uncooled cycle, the cycle with added coolant has both lower temperature and entropy values ​​at the bottom left corner. This is due to the increase in mass and decrease in temperature resulting from the addition of coolant. Therefore, the cycle with added coolant has lower temperature and entropy at the top right corner relative to the uncooled cycle. This point represents the combustion peak temperature. Therefore, the amount of cooling can be controlled so that this combustion peak temperature is below a selected threshold. This can suppress NOx formation, but because the same amount of heat can be released, a corresponding decrease in engine efficiency can be avoided. This is because the ratio between the initial and final pressures in the combustion cylinder can be the same for both cooled and uncooled cycles, and the engine cycle efficiency is determined based on this ratio. In each cycle, the slope of the straight line from the top left to the top right corner represents the efficiency of the conversion from heat energy to pressure. The flatter the slope, the higher the conversion efficiency. Figure 3 It can be seen that as the slope becomes shallower, the cooling cycle can improve the conversion efficiency from heat energy to pressure.

[0055] Figure 4 It shows Figure 3 An exemplary temperature-entropy plot of the operation of a split-cycle internal combustion engine is shown, with a line added representing constant pressure. The constant pressure line indicates that for both cycles, the ratio of the final combustion pressure to the initial pressure is the same. As a result, both cycles operate at the same engine efficiency level. However, because the temperature of the "cooled" cycle is controlled to be lower than that of the uncooled cycle, the maximum combustion temperature may be reduced. Conversely, this can suppress the formation of NOx and / or particulates.

[0056] Figure 5 A graph illustrating different combustion onset temperatures mapped to their respective combustion endpoints for n-dodecane, methane (CH4), and isooctane is shown. The graph also provides an indication of the equivalence ratio for each fuel at the onset temperature. The graph also shows the region of endpoint temperatures where NOx formation typically occurs; the endpoint of the line shown is approximately 2200 Kelvin. Generally, the NOx production temperature remains the same for the fuels discussed herein. For example, a selected threshold can be chosen based on typical values ​​of the temperatures at which NOx formation occurs. The graph also shows the region of onset temperatures where complete combustion of the fuel typically occurs. As shown, this region extends from approximately 690 Kelvin to approximately 1600 Kelvin. For example, a cooling threshold can be chosen based on the lower values ​​of the range where complete combustion occurs. This is because, for combustion onset temperatures below these lower values, combustion efficiency may be lower because the fuel cannot be fully ignited and burned.

[0057] This figure shows that, using n-dodecane as fuel, with an initial temperature range of 690 Kelvin to 820 Kelvin, complete combustion may occur without reaching the NOx region at the final combustion temperature. The figure illustrates what happens within this temperature range when the equivalence ratio is 0.4 to 0.48. For equivalence ratios of 0.5 and 0.52, at the lower initial temperatures within this range, the final combustion temperature may not reach the NOx region. However, at the higher initial temperatures, the final combustion temperature may reach the NOx region. As an example, with an equivalence ratio of 0.5 and an initial temperature of approximately 690 Kelvin, the combustion finish temperature is approximately 2100 Kelvin and is not in the NOx region. As another example, with an equivalence ratio of 0.5 and an initial temperature of 820 Kelvin, the combustion finish temperature is approximately 2220 Kelvin and is in the NOx region. This demonstrates that, for a given equivalence ratio, by controlling the initial temperature within a certain range, the final combustion temperature can avoid the NOx region, thereby suppressing NOx formation.

[0058] As shown in the figure, the equivalence ratio is the fuel-air equivalence ratio. For dodecane, when the fuel-air equivalence ratio is 0.4, the air-fuel equivalence ratio (λ) is 2. The fuel-air equivalence ratio can be selected based on a dilution threshold. The dilution ratio can be defined based on the fuel-air equivalence ratio. For example, the dilution threshold can be selected based on a fuel-air equivalence ratio of 0.4; it could be 0.42; it could be 0.44; it could be 0.46; it could be 0.48; it could be 0.5. If the dilution of the fuel and working fluid mixture is below a certain value, particulate formation may occur. The dilution threshold can be selected based on a specific value. Particulate formation can include the formation of soot in the engine. The dilution of the mixture between the working fluid and fuel can be controlled so that the mixture is sufficiently dilute to avoid particulate formation. Typically, particulate formation occurs as a result of a fuel "enrichment zone" where the fuel is not mixed with enough oxygen, thus resulting in incomplete combustion. Combustion can also be controlled to avoid the formation of compounds HC and CO, the presence of which often leads to ineffective combustion. The stoichiometric ratio can be based on the local stoichiometric ratio; it can be based on the average stoichiometric ratio of the combustion cylinder; or it can be based on both. On the other hand, Figure 1 or Figure 2The engine 100 can be operated such that the controller 60 controls at least one thermodynamic property of the working fluid within the bridging channel 30, thereby ensuring that the working fluid flowing into the combustion cylinder 20 meets selected evaluation criteria. Specifically, the controller 60 is configured to control at least one of the pressure and density of the working fluid in the bridging channel 30, such that the working fluid flows into the combustion cylinder 20 at a velocity greater than a velocity threshold. The velocity threshold is selected such that the working fluid flowing into the combustion cylinder 20 allows for lean mixing of the fuel with the working fluid in the combustion cylinder 20. For example, the working fluid may flow through the intake valve 18 at a certain velocity, thereby generating significant turbulence and causing the fluid to flow rapidly through the fuel injector 82. When fuel is injected into the combustion cylinder 20, the fuel can be properly dispersed due to the flow velocity of the working fluid. This reduces the amount of "fuel pouches" that burn at temperatures higher than their ambient temperature, thus reducing the formation of NOx and / or soot. This also ensures that the fuel is completely reacted, leaving no pyrolysis products, and allows a larger proportion of fuel to be consumed to produce useful output.

[0059] In operation, controller 60 is configured to receive an indication of at least one of the pressure and density of the working fluid in the bridging channel 30. The indication can be received from bridging sensor 31, which can be configured to measure a suitable thermodynamic parameter from which the pressure and / or density can be determined. Controller 60 can determine the pressure and / or density using a lookup table or mathematical model that provides a mapping between the measured parameter and corresponding values ​​of pressure and / or density. Controller 60 is configured to compare this determined value with an input threshold. The input threshold can be a value of the measured parameter in the bridging channel that is expected to produce working fluid flowing into the combustion cylinder at a rate greater than or equal to a velocity threshold. Controller 60 is configured to control the pressure and / or density of the working fluid based on this comparison. The pressure and / or density of the working fluid are controlled such that the fluid flows into the combustion cylinder 20 at a rate greater than the velocity threshold.

[0060] The velocity threshold is selected as a velocity that causes fluid inflow and turbulent flow in the combustion cylinder 20 to provide a lean mixture of fuel and working fluid. The value of the velocity threshold can be determined based on the pressure and / or density of the working fluid in the bridging channel 30, and the dimensions of the combustion cylinder 20 and the intake valve 18, which can be used to model the fluid flowing into the combustion cylinder 20. Therefore, a velocity threshold is selected such that the working fluid flows into the combustion cylinder 20 at this velocity threshold, resulting in a lean mixture of fuel. This lean mixture of fuel is selected to ensure complete combustion and suppress particulate generation. Alternatively, the leanness can be selected such that not all fuel is ignited at once, but rather the fuel ignition is staggered throughout the duration of the combustion stroke, as this can provide a more consistent power output from the engine 100. For example, the speed threshold can be greater than 350 m / s; it could be 345 m / s; it could be 343 m / s; it could be 340 m / s; it could be 335 m / s; it could be 330 m / s; it could be 325 m / s; it could be 320 m / s; it could be 310 m / s; it could be 300 m / s. However, it should be understood that this value depends on different engine parameters and can therefore be considerably higher or lower. For example, pressure or density can affect the value of the speed threshold. Typically, at these speeds, the fluid flow into the combustion cylinder 20 will be a blocked flow due to the disruption of the working fluid flow into the combustion cylinder 20 caused by the breaking of the sound barrier.

[0061] The input threshold is selected based on a velocity threshold and / or a selected level of turbulence within the combustion cylinder 20. For example, the input threshold can be selected based on empirical data and / or a mathematical model, which provides an indication of the relevant level of turbulence within the combustion cylinder 20. The input threshold can be selected such that a working fluid having a pressure and / or density at the input threshold will flow into the combustion cylinder 20 at the velocity threshold. In response to determining that the pressure and / or density of the working fluid is greater than the input threshold, the controller 60 is configured to control the pressure and / or density of the working fluid. The controller 60 can use a coolant system to control the pressure and / or density of the working fluid. In response to determining that the pressure and / or density is lower than the input threshold, the controller 60 is configured to control the operation of the coolant system. This can lower the temperature of the working fluid, which can result in a higher pressure and / or density in the bridging channel 30. For example, in an engine 100 with 973 K and 7 MPa, lowering the temperature to 700 K would increase the density by 40%. The operational status of the coolant system can be determined based on the degree of difference between the working fluid's pressure and / or density and an input threshold value. Figure 1 and Figure 2In the example, the coolant system includes a coolant injector 14 for injecting coolant into the compression cylinder 10 of the engine 100. Operation of the coolant system may include increasing the volume of coolant injected into the compression cylinder 10. The controller 60 may also control the volume of injected coolant based on determined fluid pressure and / or density. The increased pressure in the bridging channel 30 will create an increased pressure differential between the bridging channel 30 and the combustion cylinder 20, thus allowing a greater flow of working fluid into the combustion cylinder 20 in response to the intake valve 18 of the combustion cylinder 20 opening. The increased density will increase the density of the oxygen-carrying gas in the combustion cylinder 20. Another result of the increased density is a lower initial temperature of the working fluid in the combustion cylinder 20, thus reducing the likelihood of NOx formation. This increased density provides an increased gas mass, resulting in increased pressure and less temperature rise during combustion. Therefore, this also lowers the peak combustion temperature, thereby suppressing NOx formation.

[0062] On the other hand, the split-cycle internal combustion engine 100 can operate based on selected valve timing. Valve timing includes the time associated with a first position during piston cycle when the intake valve 18 moves from closed to open, and a second position during piston cycle when the intake valve 18 moves from open to closed. The first and second positions can be fixed, allowing the intake valve 18 to move at selected positions uncontrolled by the controller 60. Therefore, the controller 60 can determine an input threshold based on the selected positions. This includes determining the value of the input threshold based on the conditions of the engine 100 at each position, such that the working fluid in the bridging passage 30 at the input threshold can flow into the combustion cylinder 20 at a rate greater than a speed threshold after the intake valve 18 has moved to the open position in the first position.

[0063] On the other hand, the split-cycle internal combustion engine 100 can operate based on control of the movement of the intake valve 18 for the combustion cylinder 20. The intake valve 18 can move from a closed state to an open state. The movement to the open state includes movement of the valve such that the working fluid in the bridging passage has a cross-sectional area, allowing fluid to flow through and enter the combustion cylinder 20. The intake valve 18 can be configured to move between a closed state and multiple open states. The multiple open states can include a series of discrete states in which different cross-sectional areas are defined; it can include a continuum of states with continuously different cross-sectional areas. The controller 60 is configured to control the movement of the intake valve 18 to define a selected cross-sectional area, allowing the working fluid to flow through and enter the combustion cylinder 20.

[0064] Controller 60 is configured to control the movement of the intake valve, thereby defining a selected cross-sectional area. The controller is configured to select the selected cross-sectional area such that the working fluid in the bridging channel 30 flows through the cross-sectional area at a velocity greater than a velocity threshold and into the combustion cylinder 20. Controller 60 may determine the selected cross-sectional area based on received indications of engine parameters. For example, controller 60 may be configured to use a mathematical model (e.g., based on Bernoulli flow) to determine an estimated velocity of the fluid entering the combustion cylinder 20. Controller 60 may determine, for example, based on a mathematical model or lookup table, that the cross-sectional area needs to be limited to the selected cross-sectional area such that the working fluid flows into the combustion cylinder 20 at a velocity below a velocity threshold. Therefore, controller 60 may control the intake valve 18 to move to an open state, wherein moving to an open state includes opening the valve, but not necessarily opening the valve to its fully open state. Rather, the valve may be opened to a portion of its fully open state; for example, the intake valve may be moved to a partially open state. The degree of movement of the intake valve 18 may be based on received pressure indications in the bridging channel 30. For example, if the pressure in the bridging channel 30 is very high, the controller 60 can control the intake valve 18 to open fully because, even with a larger cross-sectional area, the working fluid can flow into the combustion cylinder 20 at a rate greater than a velocity threshold. In another example, the controller 60 can determine that the pressure in the bridging channel 30 is not very high, and therefore can control the intake valve 18 to open only slightly, in which case the defined cross-sectional area is very small, thus causing the working fluid to flow into the combustion cylinder 20 more quickly.

[0065] The controller 60 is configured to control the valve lift so that the working fluid flows into the combustion cylinder at a velocity greater than a velocity threshold. The velocity at which the working fluid flows into the combustion cylinder can be determined as the peak flow rate, which typically occurs when or shortly after the intake valve 18 opens. This velocity can be determined based on measurements from exhaust sensors. For example, if the exhaust sensors determine that NOx and / or particulate matter generation is above a threshold level, the flow rate is too low. By controlling the movement of the intake valve 18 such that the flow velocity of the working fluid entering the combustion cylinder 20 is greater than the velocity threshold, the mixing of air and fuel in the combustion cylinder can be supplied with a lean-to-light ratio greater than the lean-to-light threshold. The lean-to-light threshold can thus suppress particulate formation when the fuel and working fluid are sufficiently mixed such that each fuel cell is supplied with enough oxygen for complete combustion and therefore suppresses particulate formation. Controlling the flow velocity to be greater than the velocity threshold also reduces stress on the fuel injector 82 because less pressure is placed on the fuel injector 82 in terms of fuel and working fluid mixing, which can extend injector life. Additionally, operating the intake valve 18 with a low lift reduces the time it takes for it to move from its closed state to its open state due to the smaller distance it travels. This accelerates the process of introducing working fluid from the bridging channel 30 into the combustion cylinder 20. As a result, the inlet valve 18 can open later during the piston cycle. The controller 60 can determine the movement of the intake valve 18 based on data associated with its design. For example, valve dimensions, such as its shape or surface friction level, can be considered. It should be understood that details of the fluid flow path (e.g., shape, length, diameter, etc.) from the bridging channel 30 into the combustion cylinder 20 can affect the flow velocity. When determining the cross-sectional area defined by the intake valve 18 for fluid flow, the controller 60 can access a lookup table specifically for its inlet valve 18.

[0066] On the other hand, the split-cycle internal combustion engine 100 can operate based on variable valve timing. This may include the controller 60 selecting first and second positions based on determined values ​​for the pressure and / or density of the working fluid, such that the working fluid flows into the combustion cylinder 20 at a rate greater than a speed threshold after the inlet valve 18 has been moved to the open state in the selected first position.

[0067] Now we will combine Figure 6 Describes an operating method for a split-cycle internal combustion engine, for example Figure 1 and 2The method describes a split-cycle internal combustion engine 100. In step 600, the method begins and proceeds to step 610, where a peak temperature indication is received. As described above, this indication can be received from one or more sensors and can provide information about engine parameters. In step 620, based on the indication received in step 610, a combustion peak temperature in the combustion cylinder 200 is determined. The peak temperature can be determined as described above. In step 630, the determined peak temperature is compared to a selected threshold. In response to determining that the peak temperature is less than the selected threshold, the method proceeds to step 640, where the peak temperature is compared to a cooling threshold. In step 640, if the determined peak temperature is greater than the cooling threshold, the peak temperature of the engine is determined to be within a suitable range. The method then cycles back to the starting point, where another peak temperature indication is received. This cycling can occur on a variable time scale, for example, indications can be received during selected time periods; during engine start-up, indications may be received more frequently, where the values ​​of engine parameters will vary more significantly. In response to determining at step 630 that the determined peak temperature is greater than a selected threshold, or at step 640 that it is less than a cooling threshold, the method proceeds to step 650. In step 650, based on the determined peak temperature, the coolant system is controlled to regulate the temperature of the working fluid. The temperature can be adjusted to keep the combustion peak temperature within an appropriate range. The method then loops back to step 610. In response to a loop from step 650 instead of step 640, the frequency of receiving indications can be higher.

[0068] Now we will combine Figure 7 Describes an operating method for a split-cycle internal combustion engine, for example Figure 1 and 2 100 split-cycle internal combustion engine.

[0069] Steps 700 to 740 of this method correspond to the above. Figure 6 Steps 600 to 640 are therefore not described further. In step 750, in response to the determined peak temperature being greater than a selected threshold or the determined peak temperature being less than a cooling threshold, the first and second positions of the corresponding intake valve (open and closed) are selected to adjust the temperature of the working fluid. The temperature of the working fluid can be adjusted to move the combustion peak temperature into a suitable range (e.g., between the cooling threshold and the selected threshold).

[0070] Now we will combine Figure 8 Describes an operating method for a split-cycle internal combustion engine, for example Figure 1 and 2 100 split-cycle internal combustion engine.

[0071] In step 800, the method begins and proceeds to step 810, where an indication of engine parameters is received. In step 820, ignition parameters for the fuel are determined based on the indication received in step 810. Ignition parameters can be determined as described above. In step 830, the ignition parameters are compared to an ignition threshold. In response to determining that the ignition parameters are less than a selected threshold, the method proceeds to step 840, where the ignition parameters are compared to an overreaction threshold. In response that the ignition parameters are less than the overreaction threshold, the ignition parameters are considered to be within a suitable range, and the method loops back to step 810; this loop can be as described above. In response that the ignition parameters are less than the ignition threshold or greater than the overreaction threshold, the method proceeds to step 850, where a reactivity regulator is operated, for example, to adjust the working fluid so that the reactivity is within a suitable range for engine operation.

[0072] Now we will combine Figure 9 Describes an operating method for a split-cycle internal combustion engine, for example Figure 1 and 2 100 split-cycle internal combustion engine.

[0073] Steps 900 to 940 of this method correspond to the above. Figure 6 Steps 600 to 640 are therefore not described further. In step 950, in response to the determined peak temperature being greater than a selected threshold or less than a cooling threshold, the injection position of the injector is selected. As described above, the injection position is selected to regulate the temperature of the working fluid.

[0074] Now we will combine Figure 10 Describes an operating method for a split-cycle internal combustion engine, for example Figure 1 and 2 The split-cycle internal combustion engine 100. In step 1000, the method begins and proceeds to step 1010, where an indication of peak temperature is received. As described above, an estimate of the combustion peak temperature can be determined based on the indication received at step 1010. In step 1030, the coolant system is controlled such that the combustion peak temperature is within a selected range. This step may include increasing and / or decreasing the cooling of the working fluid based on whether the combustion peak temperature is low or high relative to the selected range.

[0075] Now we will combine Figure 11 Describes an operating method for a split-cycle internal combustion engine, for example Figure 1 and 2 The split-cycle internal combustion engine 100. In step 1100, the method begins and proceeds to step 1110, where an indication of engine parameters is received. In step 1120, based on this indication of engine parameters, the values ​​of the engine parameters can be determined (in... Figure 11In the example, pressure and / or temperature). This determination will depend on what is included in the indication. It may include using thermodynamic relationships to process the value of one engine parameter to determine the value of another engine parameter (pressure or temperature). In step 1130, the determined parameter (pressure and / or temperature) is compared with an input threshold. In response to the parameter being greater than the input threshold, the working fluid is considered suitable for use in the combustion cylinder, and the method loops back to 1110. In response to the parameter not being greater than the input threshold, the method proceeds to step 1140, in which the parameters of the working fluid (pressure / temperature) are controlled such that the working fluid can flow into the combustion cylinder 20 at a rate greater than a velocity threshold within a suitable range. The method then loops back to step 1110.

[0076] Now we will combine Figure 12 Describes an operating method for a split-cycle internal combustion engine, for example Figure 1 and 2 The split-cycle internal combustion engine 100. Steps 1200 to 1230 of this method correspond to the above-mentioned Figure 11 Steps 1100 to 1130 are therefore not described again. In step 1240, the movement of the intake valve is controlled to define a cross-sectional area of ​​the intake valve opening through which the working fluid flows from the bridging channel 30 into the combustion cylinder 20. The selected cross-sectional area, as described above, causes the working fluid to flow into the combustion cylinder 20 at a velocity greater than a velocity threshold.

[0077] It should be understood that although the description is directed at NOx, the term NOx can be considered to cover any suitable nitrogen oxide compound, such as N2O or any other combination of nitrogen and oxygen. It should not be interpreted as being directly limited to compounds containing a single nitrogen atom.

[0078] It should be understood that the piston cycle is periodic and repetitive; therefore, any occurrence occurring later in the piston cycle can refer to an event occurring at a later time. Each piston cycle can be considered to begin with the combustion piston 22 at its bottom dead center (“BDC”) position. During the piston cycle, the combustion piston 22 continues to move from its BDC position to its top dead center (TDC) position before returning to its BDC position. Therefore, discussions, such as whether the injector injects fuel at an earlier / later position during the piston cycle, or whether the intake valve opens or closes at an earlier / later position during the piston cycle, are based on the piston's cycle from BDC to BDC.

[0079] Referring generally to the accompanying drawings, it will be understood that the schematic functional block diagrams are used to indicate the functions of the systems and apparatus described herein. However, it will be appreciated that functionality need not be divided in this way and should not be construed as implying any particular hardware structure other than the hardware described and claimed below. The functions of one or more elements shown in the drawings may be further subdivided and / or distributed throughout the apparatus of this disclosure. In some embodiments, the functions of one or more elements shown in the drawings may be integrated into a single functional element.

[0080] In some examples, one or more storage elements may store data and / or program instructions for implementing the operations described herein. Embodiments of this disclosure provide tangible, non-transitory storage media including program instructions operable to program a processor to perform any one or more of the methods described and / or claimed herein and / or to provide data processing means described and / or claimed herein. The activities and means outlined herein may be implemented with fixed logic, such as components of logic gates, or with programmable logic, such as software and / or computer program instructions executed by a processor. Other types of programmable logic include programmable processors, programmable digital logic (e.g., field-programmable gate arrays (FPGAs), erasable programmable read-only memory (EPROMs), electrically erasable programmable read-only memory (EEPROMs)), application-specific integrated circuits (ASICs), or any other type of digital logic, software, code, electronic instructions, flash memory, optical discs, CD-ROMs, DVD-ROMs, magnetic cards or optical cards, other types of machine-readable media suitable for storing electronic instructions, or any suitable combination thereof.

[0081] From the above discussion, it will be understood that the embodiments shown in the accompanying drawings are merely exemplary and include features that can be generalized, removed, or replaced as described herein and in the claims. Other examples and variations of the apparatus and methods described herein will be apparent to those skilled in the art within the context of this disclosure.

Claims

1. A split-cycle internal combustion engine, comprising: A compression cylinder that houses a compression piston; A combustion cylinder that houses the combustion piston; The bridging channel between the compression cylinder and the combustion cylinder is arranged to provide working fluid to the combustion cylinder; A reactivity regulator that is operable to adjust the reactivity of the fuel used during combustion; as well as A controller is arranged to receive an indication of at least one of the following: (i) the pressure of the working fluid, (ii) the temperature of the working fluid, and (iii) the NO generated during combustion. x (iv) the degree of engine knock in the combustion cylinder; The controller is configured to operate the reactivity regulator to adjust the reactivity of the fuel based on received instructions.

2. The split-cycle internal combustion engine according to claim 1, wherein, The controller is configured to determine the ignition parameters associated with the fuel based on the received instructions.

3. The split-cycle internal combustion engine according to claim 2, wherein, Adjusting the reactivity of the fuel includes: in response to determining that the ignition parameter is below an ignition threshold, operating the reactivity regulator to increase the reactivity of the fuel.

4. The split-cycle internal combustion engine according to claim 2 or 3, wherein, Adjusting the reactivity of the fuel includes: in response to determining that the ignition parameter is greater than an overreactivity threshold, operating the reactivity regulator to reduce the reactivity of the fuel.

5. The split-cycle internal combustion engine according to claim 2 or 3, wherein, The ignition parameters include an indication of the fuel's ignition capability in the combustion cylinder.

6. The split-cycle internal combustion engine according to claim 2 or 3, wherein, The ignition parameters are determined based on the fuel to be used for combustion.

7. The split-cycle internal combustion engine according to claim 2 or 3, wherein, The ignition parameters include at least one of the following: (i) whether the fuel will ignite in the combustion cylinder, and (ii) the proportion of the fuel expected to ignite in the combustion cylinder.

8. The split-cycle internal combustion engine according to any one of claims 1 to 3, wherein, The reactivity regulator is operable to increase the ignition capability of the fuel.

9. The split-cycle internal combustion engine according to any one of claims 1 to 3, wherein, The reactivity regulator is operable to adjust at least one chemical or physical property of the fuel and / or working fluid supplied to the combustion cylinder to increase the ignition capability of the fuel.

10. The split-cycle internal combustion engine according to any one of claims 1 to 3, wherein, The reactivity modulator is operable to direct electromagnetic radiation to the fuel, thereby providing the fuel with an additional ignition source.

11. The split-cycle internal combustion engine according to any one of claims 1 to 3, wherein, The reactivity regulator is operable to inject oxidant into the combustion cylinder to increase the ignition capability of the fuel.

12. The split-cycle internal combustion engine according to any one of claims 1 to 3, wherein, The reactivity regulator is operable to provide a stratified combustion process and is configured to increase the ignition capability of the fuel.

13. The split-cycle internal combustion engine according to any one of claims 1 to 3, wherein, The reactivity modulator provides a source of at least one of free radicals and ozone to increase the ignition capability of the fuel.

14. A method for controlling a split-cycle internal combustion engine, comprising: A compression cylinder that houses a compression piston; A combustion cylinder that houses the combustion piston; The bridging channel between the compression cylinder and the combustion cylinder is arranged to provide working fluid to the combustion cylinder; as well as A reactivity regulator that is operable to adjust the reactivity of the fuel used during combustion; The method includes: Receive at least one of the following instructions: (i) the pressure of the working fluid, (ii) the temperature of the working fluid, (iii) the NO generated by combustion. x (iv) the degree of engine knock in the combustion cylinder; The reactivity regulator is operated based on the received instructions to increase the reactivity of the fuel.

15. A computer program product comprising program instructions configured to program a processor to execute the method of claim 14.

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