Engine system

Abstract

Provided is an engine system capable of adjusting intake air to an appropriate intake air temperature and improving the combustion efficiency of an engine when at least one of two or more types of fuel is supplied to the engine. An engine system (1) that operates by combusting at least one of two or more types of fuel including alcohol fuel such as methanol and hydrocarbon fuel such as light oil, has an intake air temperature adjustment section that is capable of adjusting the intake air temperature of intake air in an intake passage (3) based on the supply ratio of the two or more types of fuel.

Description

Technical Field

[0001] The present invention relates to an engine system that operates by burning at least one of two or more fuels. Background Technology

[0002] In the past, engine systems consisted of structures that supplied methanol or other alcohol fuels to the engine (internal combustion engine) and allowed it to burn for operation.

[0003] For example, regarding the ship disclosed in Patent Document 1, the use of a diesel engine capable of operating on methanol as fuel as the main internal combustion engine can significantly reduce sulfur oxides, particulate matter, and nitrogen oxides in the exhaust gas compared to the case of using liquefied natural gas as fuel, and can also reduce carbon dioxide emissions.

[0004] In addition, regarding engine systems, there exists a so-called dual-fuel engine: the engine is powered by supplying at least one of two or more fuels, including alcohol fuels such as methanol and hydrocarbon fuels such as light oil, and then burning them to operate.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-221645 Summary of the Invention

[0008] However, in engine systems that inject methanol or other alcohol fuels into the intake passage, insufficient vaporization can prevent them from mixing with air, potentially causing them to adhere as liquid to the walls of the intake passage. Therefore, it is necessary to increase the intake temperature to promote vaporization. On the other hand, in engine systems that directly inject light oil or other hydrocarbon fuels into the combustion chamber, a lower intake temperature is preferred in order to increase the compression ratio.

[0009] Therefore, for dual-fuel engines that supply at least one of two or more fuels, including alcohol fuels and hydrocarbon fuels, the optimal intake temperature needs to be adjusted separately because the combustion characteristics of each fuel are different.

[0010] The purpose of this invention is to provide an engine system that, when at least one of two or more fuels is supplied to the engine, can adjust the intake gas to an appropriate intake temperature to improve the engine's combustion efficiency.

[0011] To solve the above-mentioned problems, the engine system of the present invention operates by burning at least one of two or more fuels, wherein the engine system includes an intake air temperature adjustment unit that can adjust the intake air temperature based on the supply ratio of the two or more fuels.

[0012] Invention Effects

[0013] According to the present invention, an engine system is provided that, when at least one of two or more fuels is supplied to the engine, can adjust the intake gas to an appropriate intake temperature to improve the combustion efficiency of the engine. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating an example of an engine system according to an embodiment of the present invention.

[0015] Figure 2 This is a schematic diagram illustrating a first modified example of an engine system according to an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram illustrating a second variation of the engine system according to an embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram illustrating a third variation of an engine system according to an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures

[0019] 1…Engine system, 2…Engine, 3…Intake passage, 3a…Intake air temperature acquisition unit, 4…Exhaust passage, 5…Turbocharger, 5a…Turbine, 5b…Compressor, 6…Heat exchange unit, 6a…Heat exchange medium passage, 6b…Medium flow rate adjustment unit, 7…First fuel supply unit, 7a…Injection pressure acquisition unit, 8…Second fuel supply unit, 10…Control unit, 11…Cylinder block, 12…Cylinder, 12a…Combustion chamber, 13…Cylinder block, 14…Piston, 15…Cylinder head, 16…Connecting rod, 17…Crankshaft, 18…Intake port, 19…Exhaust port, 20…Intake valve, 21…Exhaust valve, 22…First fuel tank, 23…Second fuel tank, 30…Intake gas parameter acquisition unit, 31…Intake gas dissipation unit, 31a…Dissipation passage, 31b…Dissipation amount adjustment unit, 32…Exhaust gas purification unit, 32a…Exhaust gas purification catalyst, 40…Bypass unit, 40a…Bypass passage, 40b…Bypass amount adjustment unit. Detailed Implementation

[0020] The engine system 1, which is an embodiment of the present invention, will be described with reference to the accompanying drawings. Figure 1 As shown, the engine system 1 includes an engine 2, an intake passage 3, an exhaust passage 4, a turbocharger 5, a heat exchange unit 6 (intake temperature adjustment unit), a first fuel supply unit 7, a second fuel supply unit 8, and a control unit 10.

[0021] In this embodiment, in particular, the engine system 1 supplies at least one of two or more fuels with different combustion characteristics, including alcohol fuels such as methanol and hydrocarbon fuels such as light oil, to the engine 2, which is an internal combustion engine, and operates it by combustion. The engine 2 is a dual-fuel engine capable of operating using air, including alcohol fuels and hydrocarbon fuels.

[0022] Engine system 1 operates in any of the following modes: gas mode, in which engine 2 is operated by supplying only alcohol fuel; diesel mode, in which engine 2 is operated by supplying only hydrocarbon fuel; and mixed combustion mode, in which engine 2 is operated by supplying both alcohol fuel and hydrocarbon fuel at a predetermined supply ratio. Furthermore, in mixed combustion mode, engine system 1 can set the supply ratio of alcohol fuel to hydrocarbon fuel (e.g., 40%, 50%, 60%, etc.).

[0023] Engine 2 is configured to have multiple cylinders 12 in cylinder block 11, however, Figures 1-3 Only one cylinder 12 is shown. Each cylinder 12 consists of a cylinder body 13, a piston 14, and a cylinder head 15.

[0024] The cylinder block 13 is formed in a cylindrical shape within the cylinder block 11, for example, and the piston 14 is slidably housed within the cylinder block 13. The cylinder head 15 is mounted on the upper side of the cylinder block 13, and the cylinder block 13 and the cylinder head 15 together form a combustion chamber 12a on the inner side.

[0025] Below the cylinder block 13, the crankshaft 17 is connected to the piston 14 via a connecting rod 16, and the reciprocating motion of the piston 14 is converted into the rotational motion of the crankshaft 17 via the connecting rod 16.

[0026] In addition, the cylinder head 15 has an intake port 18 and an exhaust port 19 that communicate with the combustion chamber 12a of the cylinder block 13, and has an intake valve 20 and an exhaust valve 21 that open and close the intake port 18 and the exhaust port 19 respectively relative to the combustion chamber 12a.

[0027] The intake port 18 is connected to the intake passage 3 and introduces air (intake gas) supplied from the intake passage 3 toward the engine 2 into the combustion chamber 12a. The exhaust port 19 is connected to the exhaust passage 4 and discharges the exhaust gas generated in the combustion chamber 12a into the exhaust passage 4. When the intake valve 20 is opened, a mixture of gas and fuel (in the case of co-firing mode) or air (in the case of diesel mode) can be drawn into the combustion chamber 12a through the intake port 18. On the other hand, when the exhaust valve 21 is opened, the exhaust gas generated in the combustion chamber 12a can be discharged through the exhaust port 19.

[0028] The intake passage 3 allows air to flow in the intake direction and is supplied to each cylinder 12 of the engine 2 via the intake port 18. The exhaust passage 4 allows the exhaust gas generated in each cylinder 12 of the engine 2 and discharged via the exhaust port 19 to flow in the exhaust direction and be discharged.

[0029] A turbocharger 5 and a heat exchanger 6 are sequentially arranged upstream of the intake passage 3 in the intake direction. Furthermore, an air filter (not shown) for purifying and introducing fresh air can be installed upstream of the intake passage 3 in the intake direction. An intake temperature acquisition unit 3a is provided in the intake passage 3 to obtain the intake temperature of the intake air. The intake temperature acquisition unit 3a, for example, is composed of a temperature sensor that monitors the internal or external temperature of the intake passage 3, and is positioned downstream of the heat exchanger 6 in the intake direction. Furthermore, the intake temperature acquisition unit 3a can be installed in the atmosphere near the engine system 1.

[0030] The turbocharger 5 compresses the air (intake gas) flowing toward the engine 2 in the intake passage 3 and delivers it downstream in the intake direction. The turbocharger 5 includes a turbine 5a and a compressor 5b. The turbine 5a is disposed in the exhaust passage 4, and the compressor 5b is disposed in the intake passage 3. The exhaust gas flowing in the exhaust passage 4 rotates the turbine 5a, and the rotational force of the turbine 5a drives the compressor 5b, thereby compressing the air flowing in the intake passage 3.

[0031] The heat exchange unit 6 is an intake temperature adjustment unit that adjusts the intake temperature of the intake gas through heat exchange between the intake gas and the heat exchange medium. The heat exchange unit 6 includes: a heat exchange medium passage 6a in which the heat exchange medium flows; and a medium flow rate adjustment unit 6b for adjusting the flow rate of the heat exchange medium in the heat exchange medium passage 6a. The heat exchange unit 6 is controlled by the control unit 10, and the medium flow rate adjustment unit 6b adjusts the flow rate of the heat exchange medium, thereby controlling the degree of heat exchange between the intake gas and the heat exchange medium and adjusting the intake temperature of the intake gas.

[0032] For example, the heat exchange section 6 may be configured as an intercooler that uses a cooling medium to cool the intake gas compressed by the turbocharger 5. Alternatively, the heat exchange section 6 may be configured as a heater that uses a heating medium to heat the intake gas compressed by the turbocharger 5, or it may be configured to heat or cool the intake gas compressed by the turbocharger 5 by supplying air.

[0033] The first fuel supply unit 7 supplies alcohol fuel from the first fuel tank 22, which stores alcohol fuels such as methanol as the first fuel, to the combustion chamber 12a of each cylinder 12 of the engine 2.

[0034] For example, the first fuel supply unit 7 consists of a methanol supply device (LFSS) that provides pressurized supply of alcohol fuel from the first fuel tank 22, and a fuel valve assembly (FVT) that handles fuel supply / cut-off to the engine. When injecting alcohol fuel into the intake gas, the first fuel supply unit 7 uses a control unit 10 to control the injection quantity and timing of the alcohol fuel. Furthermore, the injection pressure of the alcohol fuel can be adjusted using the methanol supply device based on the supply pressure originating from the first fuel supply path from the first fuel tank 22.

[0035] Figure 1 The following example is shown: A first fuel supply unit 7 is provided at the intake port 18 to inject alcohol fuel into the intake port 18 and to supply alcohol fuel to the combustion chamber 12a via the intake port 18. Alternatively, the first fuel supply unit 7 may be provided at the intake passage 3 to inject alcohol fuel into the intake passage 3 and to supply alcohol fuel to the combustion chamber 12a via the intake passage 3 and the intake port 18. Alternatively, the first fuel supply unit 7 may be provided at the cylinder block 13 and the cylinder head 15 and to directly inject and supply alcohol fuel to the combustion chamber 12a.

[0036] Furthermore, the engine system 1 includes an injection pressure acquisition unit 7a that acquires the injection pressure of the alcohol fuel from the first fuel supply unit 7. For example, the injection pressure acquisition unit 7a is composed of a pressure sensor installed in the methanol supply device in the first fuel supply pipe that supplies alcohol fuel from the first fuel tank 22.

[0037] The second fuel supply unit 8 supplies hydrocarbon fuel, which is stored as a second fuel in the second fuel tank 23, to the combustion chamber 12a of each cylinder 12 of the engine 2.

[0038] For example, the second fuel supply unit 8 is composed of a micro-pilot injector that injects a small amount of hydrocarbon fuel. The second fuel supply unit 8 utilizes hydrocarbon fuel to compress and ignite a mixture of alcohol fuel and air (in the case of co-firing mode) or air (in diesel mode) within the combustion chamber 12a, thereby causing combustion. The second fuel supply unit 8 uses the control unit 10 to control the injection quantity and timing of the hydrocarbon fuel. Furthermore, the injection pressure of the hydrocarbon fuel is based on the supply pressure from the second fuel tank 23 to the second fuel supply unit 8.

[0039] Figure 1The following example is shown: A second fuel supply unit 8 is provided in the cylinder head 15 and directly injects hydrocarbon fuel into the combustion chamber 12a. Alternatively, the second fuel supply unit 8 may be provided in the intake port 18 to inject hydrocarbon fuel into the intake port 18 and supply hydrocarbon fuel to the combustion chamber 12a through the intake port 18; or, the second fuel supply unit 8 may be provided in the intake passage 3 to inject hydrocarbon fuel into the intake passage 3 and supply hydrocarbon fuel to the combustion chamber 12a through the intake passage 3 and the intake port 18.

[0040] The control unit 10 is a computer such as an ECU (Engine Control Unit) that controls the operation of the engine system 1. It has a CPU, ROM, RAM, etc., and is configured to control various parts of the engine system 1. The control unit 10 can store various programs used to control the engine system 1, and control the engine system 1 by reading and executing the programs.

[0041] Next, the basic supply control of alcohol and hydrocarbon fuels in engine system 1 will be explained.

[0042] The control unit 10 automatically switches to any of the following operating modes: gas mode, diesel mode, and mixed combustion mode, depending on the load of the engine 2 or the user's operation.

[0043] For example, in gas mode, the control unit 10 controls the combustion chamber 12a by setting the alcohol fuel supply ratio to 100% relative to hydrocarbon fuel and supplying alcohol fuel to the combustion chamber 12a via the first fuel supply unit 7. At this time, when hydrocarbon fuel is used as an ignition source in the combustion chamber 12a, the control unit 10 can control the combustion chamber 12a by supplying a small amount of hydrocarbon fuel to the combustion chamber 12a via the second fuel supply unit 8 and setting the alcohol fuel supply ratio approximately 100%. Alternatively, when ignition is performed in the combustion chamber 12a without using hydrocarbon fuel, the control unit 10 can set the alcohol fuel supply ratio to 100% without supplying hydrocarbon fuel via the second fuel supply unit 8.

[0044] In addition, in diesel mode, the control unit 10 controls the combustion chamber 12a by setting the supply ratio of alcohol fuel to hydrocarbon fuel to 0% and supplying hydrocarbon fuel to the combustion chamber 12a by the second fuel supply unit 8 without supplying alcohol fuel based on the first fuel supply unit 7.

[0045] In the mixed combustion mode, the control unit 10 controls the combustion chamber 12a by supplying alcohol fuel and hydrocarbon fuel to the combustion chamber 12a through the first fuel supply unit 7 and the second fuel supply unit 8. At this time, the injection amount of alcohol fuel and the injection amount of hydrocarbon fuel are controlled in a way that satisfies the set supply ratio set as the supply ratio of alcohol fuel to hydrocarbon fuel.

[0046] Specifically, in the 40% co-firing mode, the control unit 10 controls the first fuel supply unit 7 and the second fuel supply unit 8 to achieve an injection quantity of 40% of the total amount of alcohol fuel and hydrocarbon fuel, thus controlling the supply ratio of alcohol fuel to hydrocarbon fuel to be 40%. Similarly, in the 50% co-firing mode, the control unit 10 controls the first fuel supply unit 7 and the second fuel supply unit 8 to achieve an injection quantity of 50% of the total amount of alcohol fuel and hydrocarbon fuel, thus controlling the supply ratio of alcohol fuel to hydrocarbon fuel to be 50%. Furthermore, in the 60% co-firing mode, the control unit 10 controls the first fuel supply unit 7 and the second fuel supply unit 8 to achieve an injection quantity of 60% of the total amount of alcohol fuel and hydrocarbon fuel, thus controlling the supply ratio of alcohol fuel to hydrocarbon fuel to be 60%. Furthermore, even if it is not a gas mode (the alcohol fuel supply ratio is 100%), the maximum co-combustion ratio of the target engine system 1 (e.g., the alcohol fuel supply ratio is 80%) can be regarded as a gas mode.

[0047] In addition, the adjustment and control of the intake air temperature of the intake gas of engine system 1 will be explained.

[0048] In the co-firing mode, the control unit 10 controls the heat exchange unit 6 by adjusting the intake air temperature based on the supply ratio or co-firing rate of alcohol fuel and hydrocarbon fuel. In other words, the heat exchange unit 6 is configured to adjust the intake air temperature based on the supply ratio or co-firing rate of two or more fuels.

[0049] Specifically, the control unit 10 controls the medium flow rate adjustment unit 6b of the heat exchange unit 6 to adjust the medium flow rate of the heat exchange medium, thereby controlling the degree of heat exchange between the intake gas and the heat exchange medium and adjusting the intake temperature of the intake gas.

[0050] For example, the control unit 10 adjusts the flow rate of the heat exchange medium by controlling the flow rate adjustment unit 6b in a manner that the flow rate of the heat exchange medium when the supply ratio or co-combustion ratio of alcohol fuel to hydrocarbon fuel reaches or exceeds a predetermined threshold is smaller than the flow rate of the heat exchange medium when the supply ratio or co-combustion ratio is less than the predetermined threshold. In other words, the control unit 10 controls the flow rate adjustment unit 6b in a manner that the higher the supply ratio or co-combustion ratio of alcohol fuel to hydrocarbon fuel, the lower the flow rate of the heat exchange medium. That is, when the heat exchange unit 6 is an intercooler, the control unit 10 controls the heat exchange unit 6 in a manner that the higher the supply ratio or co-combustion ratio of alcohol fuel to hydrocarbon fuel, the higher the intake air temperature.

[0051] Furthermore, in engine system 1, regarding the intake air temperature for efficiently vaporizing (promoting vaporization) alcohol fuel in the co-firing mode, a correspondence between each alcohol fuel supply ratio or co-firing rate and the intake air temperature (target intake air temperature) for efficient vaporization at that supply ratio or co-firing rate is stored in advance using a correspondence diagram and mathematical formula. Moreover, control unit 10 uses intake air temperature acquisition unit 3a to acquire the intake air temperature (current intake air temperature) of the intake gas flowing in intake passage 3, and controls heat exchange unit 6 to adjust the intake air temperature of the intake gas flowing in intake passage 3 in a manner that makes the acquired current intake air temperature reach the target intake air temperature corresponding to the set supply ratio or co-firing rate based on the correspondence between the acquired current intake air temperature and the alcohol fuel supply ratio (set supply ratio) or co-firing rate set in the co-firing mode.

[0052] In addition, the control of the supply ratio of alcohol fuel and hydrocarbon fuel in engine system 1 is explained.

[0053] The control unit 10 controls the supply ratio of alcohol fuel to hydrocarbon fuel based on the injection pressure of alcohol fuel obtained by the injection pressure acquisition unit 7a from the first fuel supply unit 7.

[0054] Specifically, regarding engine system 1, in gas mode, the alcohol fuel supply ratio (set supply ratio) is set to 100%. Furthermore, in co-firing mode, the alcohol fuel supply ratio (set supply ratio) is also set. Control unit 10 controls the injection quantity of alcohol fuel from the first fuel supply unit 7 and the injection quantity of hydrocarbon fuel from the second fuel supply unit 8 based on the set supply ratio of alcohol fuel. Here, using the injection pressure of the alcohol fuel injected from the first fuel supply unit 7 as a reference, and based on the supply pressure of the first fuel supply path supplying alcohol fuel from the first fuel tank 22, control unit 10 sets the injection quantity of alcohol fuel from the first fuel supply unit 7 to an injection quantity (set injection quantity) corresponding to the set supply ratio of alcohol fuel, based on the case where the alcohol fuel injection pressure is a predetermined injection pressure.

[0055] However, sometimes the actual injection pressure (current injection pressure) of the alcohol fuel injected from the first fuel supply unit 7 is unexpectedly different from the predetermined injection pressure. Therefore, the control unit 10 calculates the injection amount of alcohol fuel that can efficiently vaporize the alcohol fuel injected from the first fuel supply unit 7 at the current injection pressure, based on the injection pressure (current injection pressure) of the alcohol fuel based on the first fuel supply unit 7 obtained by the injection pressure acquisition unit 7a, and controls the supply ratio of alcohol fuel to hydrocarbon fuel in a way that achieves the injection amount. At this time, the control unit 10 stores in advance the correspondence between the intake temperature of the intake passage 3, the injection pressure of the alcohol fuel, and the injection amount (supply ratio) of the alcohol fuel when the alcohol fuel can be efficiently vaporized using a correspondence diagram and mathematical formula, and obtains the injection amount (supply ratio) of alcohol fuel based on the correspondence with respect to the current intake temperature of the intake passage 3 and the current injection pressure of the alcohol fuel.

[0056] Alternatively, the control unit 10 can pre-replace the control of the alcohol fuel supply ratio by storing the correspondence between the intake temperature of the intake passage 3, the injection pressure of the alcohol fuel, and the injection quantity (supply ratio) of the alcohol fuel in the case of efficient vaporization of alcohol fuel using a correspondence diagram and mathematical formula. Based on this correspondence, the target intake temperature of the intake passage 3 is obtained relative to the current injection pressure and the current injection quantity of alcohol fuel. The heat exchange unit 6 is controlled in such a way that the intake temperature of the intake passage 3 reaches the target intake temperature to adjust the intake temperature of the intake gas flowing in the intake passage 3.

[0057] As described above, according to this embodiment, the engine system 1, which operates by burning at least one of two or more fuels, includes an intake air temperature adjustment unit capable of adjusting the intake air temperature of the intake passage 3 based on the supply ratio of the two or more fuels. In the engine system 1, the two or more fuels include alcohol fuels such as methanol, and hydrocarbon fuels such as light oil.

[0058] Therefore, regarding engine system 1, when at least one of two or more fuels with different combustion characteristics is supplied to engine 2, the intake temperature of intake passage 3 is adjusted based on the supply ratio of the two or more fuels to achieve a temperature suitable for the supplied fuel, thereby improving the combustion efficiency of engine 2 by utilizing appropriately vaporized fuel.

[0059] Furthermore, according to this embodiment, as an intake air temperature adjustment unit, the engine system 1 includes a heat exchange unit 6 that adjusts the intake air temperature by heat exchange between the intake air and the heat exchange medium. The heat exchange unit 6 includes a medium flow rate adjustment unit 6b for adjusting the flow rate of the heat exchange medium, and the intake air temperature is adjusted by controlling the medium flow rate adjustment unit 6b. Specifically, the medium flow rate adjustment unit 6b adjusts the medium flow rate when the alcohol fuel supply ratio is above a predetermined threshold to a smaller medium flow rate than when the alcohol fuel supply ratio is below the threshold.

[0060] Therefore, with respect to engine system 1, the intake air temperature can be adjusted by adjusting the flow rate of the heat exchange medium using the heat exchange unit 6.

[0061] Furthermore, according to this embodiment, the engine system 1 includes an intake air temperature acquisition unit 3a for acquiring the intake air temperature of the intake passage 3. Intake air temperature adjustment units such as the heat exchange unit 6 adjust the intake air temperature based on the current intake air temperature acquired by the intake air temperature acquisition unit 3a and a target intake air temperature corresponding to the alcohol fuel supply ratio. The intake air temperature acquisition unit 3a is located downstream of the heat exchange unit 6.

[0062] Therefore, regarding engine system 1, the current intake air temperature of intake passage 3 can be fed back to allow for more precise adjustment of the intake air temperature for the alcohol fuel supply ratio. At this time, engine system 1 can obtain the current intake air temperature using the intake air temperature acquisition unit 3a, which is in an optimal position within intake passage 3.

[0063] Furthermore, according to this embodiment, the engine system 1 includes: a first fuel supply unit 7, which is a fuel injection valve for injecting alcohol fuel; and an injection pressure acquisition unit 7a, which acquires the injection pressure of the alcohol fuel based on the first fuel supply unit 7. The intake air temperature adjustment unit controls the alcohol fuel supply ratio or the intake air temperature of the intake passage 3 based on the alcohol fuel injection pressure acquired by the injection pressure acquisition unit 7a.

[0064] Regarding engine system 1, sometimes the control unit 10 is unable to control the injection pressure of the alcohol fuel based on the supply pressure from the first fuel tank 22 to the first fuel supply unit 7, and therefore, the current injection pressure of the alcohol fuel unexpectedly differs from the predetermined injection pressure. Even in this case, regarding engine system 1, by controlling the supply ratio of the alcohol fuel or the intake temperature of the intake passage 3 based on the current injection pressure of the alcohol fuel, the combustion efficiency of engine 2 can be improved by properly vaporizing the alcohol fuel.

[0065] Furthermore, in the first variation of this embodiment, such as Figure 2 As shown, the engine system 1 includes an intake gas parameter acquisition unit 30, an intake gas dissipation unit 31, and an exhaust gas purification unit 32.

[0066] The inhalation gas parameter acquisition unit 30 acquires inhalation gas parameters, such as inhalation gas flow rate and inhalation gas pressure, which are related to the inhalation gas in the intake passage 3, at a position upstream or downstream of the heat exchange unit 6 in the intake direction. For example, the inhalation gas parameter acquisition unit 30 includes a flow sensor that detects and acquires the inhalation gas flow rate and a pressure sensor that detects and acquires the inhalation gas pressure.

[0067] The intake gas evaporation section 31 adjusts the gas mixture by evaporating the intake gas from the intake passage 3 that allows the intake gas to flow, and adjusts the intake gas quantity for optimal combustion based on the intake temperature after the intake gas temperature adjustment.

[0068] For example, the intake gas escaping section 31 includes: an escaping passage 31a for escaping intake gas from the intake passage 3; and an escaping amount adjustment section 31b for adjusting the escaping amount of intake gas in the escaping passage 31a. The intake gas escaping section 31 is configured to allow intake gas to escap from the intake passage 3 to the exhaust passage 4 via the escaping passage 31a, which bypasses the intake passage 3.

[0069] The intake gas venting section 31 is located downstream of the heat exchange section 6 in the intake direction and is connected to the intake passage 3. Figure 4 The following example is shown: the intake gas venting section 31 is connected to the exhaust passage 4 at a position further downstream of the turbocharger 5 in the exhaust direction, or the intake gas venting section 31 may be connected to the exhaust passage 4 at a position further upstream of the turbocharger 5, or it may be open to the atmosphere.

[0070] The exhaust gas purification unit 32 includes an exhaust gas purification catalyst 32a, which promotes a reduction reaction that selectively reduces nitrogen oxides in the exhaust gas flowing through the exhaust passage 4 to nitrogen and water, thereby purifying the exhaust gas. The exhaust gas purification unit 32 is located downstream of the turbocharger 5 in the exhaust passage 4. The exhaust gas purification unit 32 is configured to operate in a regeneration mode that regenerates the exhaust gas purification catalyst 32a.

[0071] In the first variation, the engine system 1 uses the control unit 10 and adjusts the gas mixture based on the intake gas parameters obtained by the intake gas parameter acquisition unit 30 and the intake gas emission amount based on the intake gas emission unit 31.

[0072] Regarding engine system 1, alcohol fuels such as methanol are more suitable for combustion with less intake gas compared to hydrocarbon fuels such as light oil. Therefore, if the intake gas is burned in the same amount as hydrocarbon fuel, it will lead to an increase in misfires and unburned fuel. Therefore, regarding engine system 1, in the case of an increase in misfires and unburned fuel due to intake gas parameters, by increasing the intake gas emission amount based on the intake gas emission section 31, the proportion of alcohol fuel relative to the intake gas can be increased, thereby improving the combustion efficiency of engine 2.

[0073] Furthermore, regarding engine system 1, when exhaust gas purification unit 32 operates in regeneration mode that regenerates exhaust gas purification catalyst 32a, the control unit 10 controls the emission amount adjustment unit 31b of intake gas emission unit 31 to adjust the emission amount of intake gas from intake passage 3.

[0074] In engine system 1, regarding the mixture of alcohol fuel and intake gas supplied to engine 2, by increasing the intake gas, the proportion of alcohol fuel relative to the intake gas can be reduced, thereby increasing the amount of unburned fuel. This unburned fuel can be used as a heat source in the regeneration mode where the exhaust gas purification catalyst is regenerated using heat. That is, regarding engine system 1, when the exhaust gas purification catalyst 32a is regenerated, by reducing the amount of intake gas emitted based on the intake gas emission section 31, the amount of unburned alcohol fuel can be increased, thereby enabling efficient regeneration of the exhaust gas purification catalyst 32a.

[0075] Furthermore, in the second variation of this embodiment, such as Figure 3 As shown, the engine system 1 includes a bypass section 40.

[0076] The bypass section 40 functions as an intake temperature adjustment unit to regulate the intake temperature of the intake gas in the intake passage 3 by allowing the intake gas to bypass the heat exchange section 6 in the intake passage 3. The bypass section 40 bypasses the heat exchange section 6 in the intake direction at a position further upstream and downstream. The bypass section 40 includes: a bypass passage 40a through which the intake gas flows bypassing the heat exchange section 6; and a bypass amount adjustment unit 40b for adjusting the bypass amount of the intake gas in the bypass passage 40a.

[0077] In the second variation, the engine system 1 uses the control unit 10 to adjust the bypass amount based on the bypass section 40, thereby controlling the amount of intake gas undergoing heat exchange in the heat exchange section 6 and adjusting the intake gas temperature of the intake passage 3. For example, if the heat exchange section 6 is an intercooler, the control unit 10 increases the bypass amount of intake gas in the bypass section 40, thereby reducing the amount of intake gas cooled in the heat exchange section 6 and raising the intake gas temperature.

[0078] Furthermore, in the third variation of this embodiment, such as Figure 4 As shown, in the engine system 1, the heat exchange unit 6 includes two or more heat exchange medium passages 6a through which the heat exchange medium flows, and includes two or more medium flow adjustment units 6b for adjusting the medium flow rate of the heat exchange medium in the two or more heat exchange medium passages 6a respectively. In other words, the heat exchange unit 6 includes two or more heat exchangers composed of heat exchange medium passages 6a and medium flow adjustment units 6b.

[0079] According to the third modification, the heat exchange section 6 can efficiently adjust the intake temperature of the intake gas by utilizing multiple heat exchangers to exchange heat with the intake gas.

[0080] Furthermore, in the above embodiment, an example was described in which the control unit 10 in the engine system 1 controls the heat exchange unit 6 by adjusting the intake air temperature based on the supply ratio of alcohol fuel and hydrocarbon fuel; however, the present invention is not limited to this example. In other examples, the engine system 1 can be configured with multiple levels of combustion modes corresponding to multiple levels of supply ratios (e.g., every 10% of the supply ratio), and the control unit 10 can control the heat exchange unit 6 by adjusting the intake air temperature based on the level of the combustion mode.

[0081] Furthermore, in the above embodiment, an example of using the heat exchange section 6 and the bypass section 40 as an intake air temperature adjustment unit in the engine system 1 was described. Here, the engine system 1 can use any one of the heat exchange section 6 and the bypass section 40 as an intake air temperature adjustment unit, or it can combine two or more of the heat exchange section 6 and the bypass section 40 as an intake air temperature adjustment unit. Moreover, the engine system 1 can select one or more of the heat exchange section 6 and the bypass section 40 as an intake air temperature adjustment unit based on parameters such as the supply ratio of alcohol fuel to hydrocarbon fuel, the level of co-firing mode, and the current intake air temperature of the intake passage 3.

[0082] Furthermore, modifications may be made to the invention without departing from the inventive spirit or concept as understood in the claims and the entire specification. Additionally, the engine system accompanying such modifications is also included in the technical concept of the invention.

[0083] [Postscript to the Invention]

[0084] The following is a summary of the invention derived from the above embodiments. Furthermore, the structures and processing functions described in the following notes can be selected and combined arbitrarily.

[0085] <Postscript 1>

[0086] An engine system that operates by burning at least one of two or more fuels, characterized in that,

[0087] The engine system includes an intake air temperature adjustment unit that can adjust the intake air temperature based on the supply ratio of the two or more fuels.

[0088] <Appendix 2>

[0089] According to the engine system described in Appendix 1, its characteristics are as follows:

[0090] The two or more types of fuel include alcohol fuels.

[0091] <Appendix 3>

[0092] According to the engine system described in Appendix 1 or 2, it is characterized in that,

[0093] The intake air temperature adjustment unit includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium.

[0094] The heat exchange section includes a medium flow rate adjustment section for adjusting the flow rate of the heat exchange medium.

[0095] The intake air temperature is adjusted by controlling the medium flow rate adjustment unit.

[0096] <Appendix 4>

[0097] According to the engine system described in Appendix 3, its characteristics are as follows:

[0098] The two or more types of fuel include alcohol fuels.

[0099] The medium flow rate adjustment unit adjusts the medium flow rate such that when the supply ratio of the alcohol fuel reaches or exceeds a predetermined threshold, the medium flow rate is smaller than when the supply ratio of the alcohol fuel is less than the threshold.

[0100] <Appendix 5>

[0101] The engine system described in any one of Appendices 1 to 4 is characterized in that,

[0102] The intake air temperature adjustment unit includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium.

[0103] The engine system further includes an intake gas parameter acquisition unit, which is used to acquire intake gas parameters related to the intake gas on the upstream or downstream side of the heat exchange unit.

[0104] The engine system includes an intake gas venting section for venting the intake gas from an intake passage through which the intake gas flows.

[0105] The amount of inhaled gas emitted by the inhaled gas emission unit is adjusted based on the inhaled gas parameters obtained by the inhaled gas parameter acquisition unit.

[0106] <Appendix 6>

[0107] According to the engine system described in Appendix 5, its characteristics are as follows:

[0108] The engine system also features an exhaust gas purification catalyst.

[0109] The intake temperature adjustment unit adjusts the amount of intake gas emitted during the regeneration of the exhaust gas purification catalyst.

[0110] <Appendix 7>

[0111] The engine system described in any one of Appendices 1 to 6 is characterized in that,

[0112] The engine system also includes an intake air temperature acquisition unit for acquiring the intake air temperature.

[0113] The intake temperature adjustment unit adjusts the intake temperature based on the current intake temperature obtained by the intake temperature acquisition unit and the target intake temperature corresponding to the supply ratio.

[0114] <Appendix 8>

[0115] According to the engine system described in Appendix 7, its characteristics are as follows:

[0116] The intake air temperature adjustment unit includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium.

[0117] The intake air temperature acquisition unit is located downstream of the heat exchange unit.

[0118] <Appendix 9>

[0119] The engine system described in any one of Appendices 1 to 8 is characterized in that,

[0120] The engine system includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium.

[0121] The intake air temperature adjustment unit also includes a bypass section for allowing the intake air to bypass the heat exchange unit.

[0122] The bypass section includes a bypass flow rate adjustment section for adjusting the bypass flow rate of the inhaled gas, which adjusts the bypass flow rate based on the supply ratio.

[0123] <Postscript 10>

[0124] The engine system described in any one of Appendices 1 to 9 is characterized in that,

[0125] The engine system includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium.

[0126] The heat exchange section includes two or more heat exchange medium passages that allow the heat exchange medium to circulate.

[0127] <Postscript 11>

[0128] The engine system described in any one of Appendices 2 to 10 is characterized in that,

[0129] The engine system also features:

[0130] Fuel injection valve, which injects the alcohol fuel; and

[0131] The injection pressure acquisition unit acquires the injection pressure of the alcohol fuel based on the fuel injection valve.

[0132] The intake air temperature adjustment unit controls the supply ratio or the intake air temperature based on the injection pressure obtained by the injection pressure acquisition unit.

Claims

1. An engine system that operates by burning at least one of two or more fuels, characterized in that, The engine system includes an intake air temperature adjustment unit that can adjust the intake air temperature based on the supply ratio of the two or more fuels.

2. The engine system according to claim 1, characterized in that, The two or more types of fuel include alcohol fuels.

3. The engine system according to claim 1, characterized in that, The intake air temperature adjustment unit includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium. The heat exchange section includes a medium flow rate adjustment section for adjusting the flow rate of the heat exchange medium. The intake air temperature is adjusted by controlling the medium flow rate adjustment unit.

4. The engine system according to claim 3, characterized in that, The two or more types of fuel include alcohol fuels. The medium flow rate adjustment unit adjusts the medium flow rate such that when the supply ratio of the alcohol fuel reaches or exceeds a predetermined threshold, the medium flow rate is smaller than when the supply ratio of the alcohol fuel is less than the threshold.

5. The engine system according to claim 1, characterized in that, The intake air temperature adjustment unit includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium. The engine system further includes an intake gas parameter acquisition unit, which is used to acquire intake gas parameters related to the intake gas on the upstream or downstream side of the heat exchange unit. The engine system includes an intake gas venting section for venting the intake gas from an intake passage through which the intake gas flows. The amount of inhaled gas emitted by the inhaled gas emission unit is adjusted based on the inhaled gas parameters obtained by the inhaled gas parameter acquisition unit.

6. The engine system according to claim 5, characterized in that, The engine system also features an exhaust gas purification catalyst. The intake temperature adjustment unit adjusts the amount of intake gas emitted during the regeneration of the exhaust gas purification catalyst.

7. The engine system according to claim 1, characterized in that, The engine system also includes an intake air temperature acquisition unit for acquiring the intake air temperature. The intake temperature adjustment unit adjusts the intake temperature based on the current intake temperature obtained by the intake temperature acquisition unit and the target intake temperature corresponding to the supply ratio.

8. The engine system according to claim 7, characterized in that, The intake air temperature adjustment unit includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium. The intake air temperature acquisition unit is located downstream of the heat exchange unit.

9. The engine system according to claim 1, characterized in that, The engine system includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium. The intake air temperature adjustment unit also includes a bypass section for allowing the intake air to bypass the heat exchange unit. The bypass section includes a bypass flow rate adjustment section for adjusting the bypass flow rate of the inhaled gas, which adjusts the bypass flow rate based on the supply ratio.

10. The engine system according to claim 1, characterized in that, The engine system includes a heat exchange unit that adjusts the intake air temperature through heat exchange between the intake gas and the heat exchange medium. The heat exchange section includes two or more heat exchange medium passages that allow the heat exchange medium to circulate.

11. The engine system according to claim 2, characterized in that, The engine system also features: Fuel injection valve, which injects the alcohol fuel; and The injection pressure acquisition unit acquires the injection pressure of the alcohol fuel based on the fuel injection valve. The intake air temperature adjustment unit controls the supply ratio or the intake air temperature based on the injection pressure obtained by the injection pressure acquisition unit.

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