Internal combustion engine system

Abstract

This simple configuration recovers exhaust heat from exhaust gases, enabling the supercharging of air to the internal combustion engine. [Solution] The internal combustion engine system comprises a supercharger having a tank for storing liquefied gaseous fuel, a heat exchanger for heating the gaseous fuel from the tank by heat exchange with exhaust gas to generate superheated steam, a turbine driven by the superheated steam of the gaseous fuel generated in the heat exchanger, and a compressor for pressurizing the air supplied to the internal combustion engine by the driving force of the turbine, and an internal combustion engine to which the gaseous fuel after driving the turbine is supplied together with the air pressurized by the compressor and to which the exhaust gas is discharged.

Description

Technical Field

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[0001] The present disclosure relates to an internal combustion engine system.

Background Art

[0002] Patent Document 1 discloses a supercharger for an internal combustion engine that generates steam using the exhaust heat of exhaust gas, generates electricity using a generator equipped with a steam turbine, and supplies power to a motor-driven supercharger.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration of Patent Document 1, since steam is used as the working fluid for driving the supercharger, a steam circulation path, a condenser, etc. are required, and the system becomes complicated.

[0005] In consideration of the above facts, an object of the present disclosure is to recover the exhaust heat of exhaust gas with a simple configuration and enable supercharging of air to an internal combustion engine.

Means for Solving the Problems

[0006] A first aspect includes a tank that stores liquefied gas fuel, a heat exchanger that heats the gas fuel from the tank by heat exchange with exhaust gas to generate superheated steam, a turbine driven by the superheated steam of the gas fuel generated in the heat exchanger, and a compressor that pressurizes air supplied to the internal combustion engine by the driving force of the turbine. The supercharger has a compressor, and the gas fuel after driving the turbine is supplied together with the air pressurized by the compressor, and the internal combustion engine discharges the exhaust gas.

[0007] In the first embodiment, gaseous fuel from a tank is heated by heat exchange with exhaust gas to generate superheated steam, and this superheated steam of gaseous fuel drives the turbine of a turbocharger. The compressor pressurizes the air supplied to the internal combustion engine by the driving force of the turbine. The fuel that has driven the turbine is then supplied to the internal combustion engine.

[0008] Thus, in an internal combustion engine system, gaseous fuel is used as a working fluid to recover exhaust heat and drive a turbine before being consumed as fuel for the internal combustion engine. This eliminates the need for a separate working fluid path in addition to the gaseous fuel path. Therefore, exhaust heat can be recovered from the exhaust gas and used to supercharge air into the internal combustion engine with a simple configuration.

[0009] The second embodiment includes a supply pump that supplies the gas fuel from the tank to the heat exchanger and controls the supply pressure to the heat exchanger according to the supercharging pressure required by the supercharger, as in the first embodiment.

[0010] According to the second embodiment, when the required supercharging pressure is high, the supply pressure to the heat exchanger can be increased. As a result, when the expansion work in the turbine is increased, that is, when the supercharging pressure is increased, it becomes possible to increase the turbine inlet pressure, and the conversion of fuel into wet steam after expansion can be suppressed.

[0011] The third embodiment, in the first embodiment, includes a bypass channel that directs a portion of the superheated steam of the gas fuel generated in the heat exchanger to bypass the turbine, and a control valve that adjusts the flow rate of the gas fuel flowing into the bypass channel.

[0012] According to the third embodiment, by increasing or decreasing the flow rate of gas fuel flowing into the bypass passage, the flow rate of gas fuel driving the turbine is increased or decreased, making it possible to adjust the supercharging pressure. As a result, it becomes possible to adjust the supercharging pressure in the supercharger regardless of the amount of fuel consumed by the internal combustion engine.

[0013] A fourth embodiment includes, in the first embodiment, a control valve that adjusts the flow rate of air sent from the compressor to the internal combustion engine in accordance with the supercharging pressure required in the supercharger.

[0014] According to the fourth aspect, it becomes possible to adjust the boost pressure in the supercharger regardless of the amount of fuel consumed by the internal combustion engine.

[0015] The fifth embodiment includes a generator that generates electricity using the driving force of the turbine and whose power generation load can be controlled according to the supercharger pressure required by the supercharger, in accordance with the first embodiment.

[0016] According to the fifth aspect, it becomes possible to adjust the boost pressure in the supercharger regardless of the amount of fuel consumed by the internal combustion engine.

[0017] The sixth embodiment includes a control unit that controls at least one of the fuel pressure and the supercharger pressure such that the fuel pressure of the gaseous fuel supplied to the internal combustion engine is higher than the supercharger pressure in the supercharger, in the first embodiment.

[0018] According to the sixth aspect, it becomes possible to supply fuel to the internal combustion engine regardless of the supercharging pressure in the supercharger.

[0019] The seventh embodiment includes a vaporizer, which in the first embodiment is positioned between the tank and the heat exchanger, and vaporizes the gaseous fuel from the tank by heat exchange with the cooling water of the internal combustion engine.

[0020] According to the seventh embodiment, by providing a vaporizer, it becomes possible to recover waste heat not only from the exhaust gas but also from the cooling water, thereby improving thermal efficiency. [Effects of the Invention]

[0021] According to this disclosure, exhaust heat from exhaust gases can be recovered with a simple configuration, and air can be supercharged to an internal combustion engine. [Brief explanation of the drawing]

[0022] [Figure 1] It is a schematic diagram showing an internal combustion engine system according to this embodiment. [Figure 2] It is a graph showing the relationship between the required boost pressure and the supply pressure to the heat exchanger in the internal combustion engine system according to this embodiment. [Figure 3] It is a schematic diagram showing a modified example provided with a bypass circuit in the internal combustion engine system according to this embodiment. [Figure 4] It is a schematic diagram showing a modified example provided with an adjustment valve in the internal combustion engine system according to this embodiment. [Figure 5] It is a schematic diagram showing a modified example provided with a generator in the internal combustion engine system according to this embodiment. [Figure 6] It is a schematic diagram showing a modified example provided with a carburetor in the internal combustion engine system according to this embodiment.

Mode for Carrying Out the Invention

[0023] Hereinafter, an example of an embodiment according to the present invention will be described based on the drawings. However, the present disclosure is not limited to the following embodiments. When describing an embodiment with reference to the drawings in the present disclosure, the configuration of the embodiment is not limited to the configuration shown in the drawings.

[0024] In the following description of the drawings, the same parts are denoted by the same reference numerals. However, the sizes of the members in each figure are conceptual, and the relative size relationships between the members are not limited to this. Also, unless otherwise specified in the specification, the number of each component of the present disclosure is not limited to one, and a plurality of components may exist.

[0025] <Internal combustion engine system 10> First, the internal combustion engine system 10 according to this embodiment will be described. FIG. 1 is a schematic diagram showing the internal combustion engine system 10 according to this embodiment.

[0026] The internal combustion engine system 10 shown in Figure 1 is a system that burns fuel in an internal combustion engine and uses the resulting combustion gases to obtain mechanical work. As shown in Figure 1, the internal combustion engine system 10 comprises a fuel tank 12, a supply pump 14, a heat exchanger 16, a supercharger 40 having a turbine 18, a regulator 22, an injector 24, an internal combustion engine 30, and an exhaust gas purification medium 38.

[0027] <Fuel tank 12 and supply pump 14> The fuel tank 12 is a storage section for liquefied gaseous fuel 13 (hereinafter referred to as fuel 13), which is a liquefied gaseous fuel. As fuel 13, liquefied natural gas (LNG), liquefied petroleum gas (LPG), dimethyl ether (DME), and ammonia can be used.

[0028] The supply pump 14 is a pump that supplies fuel 13 contained in the fuel tank 12 to the heat exchanger 16. In this embodiment, the supply pump 14 pressurizes the fuel 13 contained in the fuel tank 12 and pumps the fuel 13 to the heat exchanger 16.

[0029] Furthermore, the internal combustion engine system 10 may consist of liquefied gas fuel as a fuel source for at least a portion of its composition, and may also be configured to supply diesel fuel, such as light oil, to the internal combustion engine 30 in addition to the liquefied gas fuel.

[0030] <Heat exchanger 16> The heat exchanger 16 vaporizes the fuel 13 from the fuel tank 12 through heat exchange with the exhaust gas. The heat exchanger 16 transfers the heat from the exhaust gas to the fuel 13, heating it and generating superheated steam. This superheated steam is supplied to the turbine 18.

[0031] In this embodiment, as shown in Figure 1, the heat exchanger 16 is positioned downstream of the exhaust gas purification medium 38 in the exhaust pipe 34. Here, the exhaust gas sent to the heat exchanger 16 has unburned components (e.g., hydrocarbons) oxidized by the exhaust gas purification medium 38, causing its temperature to rise. Therefore, by positioning the heat exchanger 16 downstream of the exhaust gas purification medium 38 in the exhaust pipe 34, the amount of exhaust heat recovered increases.

[0032] <Supercharger 40> The supercharger 40 is a device that supplies compressed air to the internal combustion engine 30. The supercharger 40 includes a turbine 18, a compressor 42, an intercooler 44, and a throttle 46.

[0033] The turbine 18 is a mechanical element driven by superheated steam of fuel 13 generated in the heat exchanger 16. The compressor 42 is a device that pressurizes the air supplied to the internal combustion engine 30 using the driving force of the turbine 18. In other words, the compressor 42 operates using the driving force of the turbine 18, compressing the air to produce compressed air.

[0034] In the supercharger 40, the air pressurized by the compressor 42 is cooled by the intercooler 44, and then the supply amount and supply pressure are adjusted by the throttle 46 before being supplied to the internal combustion engine 30.

[0035] <Regulator 22, injector 24, internal combustion engine 30, and exhaust gas purification medium 38> The internal combustion engine 30 is a prime mover in which the combustion of fuel takes place inside the engine, and the thermal energy of the combustion gases is converted into mechanical energy. As an example of the internal combustion engine 30, an engine mounted on a vehicle (for example, a four-cylinder engine) can be used.

[0036] An intake manifold 32 is attached to the internal combustion engine 30, through which vaporized fuel 13 is drawn in. An injector 24 is provided in the intake manifold 32 to supply fuel 13 to the internal combustion engine 30. In the internal combustion engine system 10, a regulator 22 for regulating the pressure of the fuel 13 is located between the turbine 18 and the injector 24. The regulator 22 controls the fuel pressure so that the fuel pressure of the gaseous fuel supplied to the internal combustion engine 30 is higher than the supercharging pressure in the supercharger 40. Note that the regulator 22 is an example of a control unit.

[0037] Furthermore, the internal combustion engine 30 is fitted with an exhaust pipe 34 that discharges the combustion gases (i.e., exhaust gases) remaining after the fuel has been burned inside. An exhaust gas purification medium 38 is fitted to the exhaust pipe 34.

[0038] The exhaust gas purification medium 38 has the function of converting nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (HC) contained in the exhaust gas into harmless carbon dioxide, water, nitrogen, oxygen, etc.

[0039] In this embodiment, the fuel 13, after driving the turbine 18, is pressure-regulated by the regulator 22 and then supplied to the internal combustion engine 30 by the injector 24. The amount of fuel supplied to the internal combustion engine 30 is controlled by the opening time of the injector 24.

[0040] Fuel 13 is burned in the internal combustion engine 30, and exhaust gas is discharged from the internal combustion engine 30 to the exhaust pipe 34. The exhaust gas is purified by the exhaust gas purification medium 38 through the exhaust pipe 34 and then discharged to the outside of the internal combustion engine system 10 (for example, into the atmosphere).

[0041] <Control of the supply pressure of fuel 13 by the supply pump 14> The supply pump 14 can control the supply pressure to the heat exchanger 16 according to the required supercharging pressure in the supercharger 40. Specifically, the supply pump 14 increases the supply pressure to the heat exchanger 16 when the required supercharging pressure is high, for example, as shown in Figure 2.

[0042] This is because, when the expansion work at turbine 18 is increased (i.e., the supercharging pressure is increased), if the inlet pressure of turbine 18 is low, the fuel is more likely to turn into wet steam after expansion.

[0043] It is possible to set the pressure of the regulator 22 to a range that does not generate wet steam, but if the inlet pressure of the turbine 18 is insufficient, the expansion work will be reduced, and the necessary boost pressure cannot be obtained. If the boost pressure is too high, it can be adjusted using the throttle 46. By setting the pressure of the regulator 22 higher than the boost pressure, fuel injection into the internal combustion engine 30 becomes possible.

[0044] <Effects and Effects of Internal Combustion Engine System 10> In the internal combustion engine system 10, fuel 13 from the fuel tank 12 is heated by heat exchange with exhaust gas to generate superheated steam, and this superheated steam of fuel 13 drives the turbine 18 of the turbocharger 40. The compressor 42 pressurizes the air supplied to the internal combustion engine 30 using the driving force of the turbine 18. Then, the fuel 13 that has driven the turbine 18 is supplied to the internal combustion engine 30.

[0045] Thus, in the internal combustion engine system 10, fuel 13 is used as a working fluid to recover exhaust heat and drive the turbine 18, and then consumed as fuel for the internal combustion engine 30. This eliminates the need for a separate working fluid passage in addition to the fuel passage 13. Therefore, exhaust heat from the exhaust gas can be recovered and air can be supercharged into the internal combustion engine 30 with a simple configuration.

[0046] In exhaust turbocharging, where the turbine 18 is driven by the flow of exhaust gas, it is necessary to increase the exhaust pressure to drive the turbine 18. In contrast, in the internal combustion engine system 10, the turbine 18 is driven by superheated steam of fuel 13, so it is not necessary to increase the exhaust pressure of the exhaust gas. Therefore, according to the internal combustion engine system 10, supercharging can be performed without increasing the exhaust pressure of the exhaust gas.

[0047] As a result, the intake pressure can be increased relative to the exhaust pressure, thereby increasing the shaft output of the internal combustion engine 30 and improving its efficiency. Furthermore, reducing the exhaust pressure reduces residual gas, which can suppress abnormal combustion such as plaque and knocking, which are problems during high-load operation.

[0048] Furthermore, with the internal combustion engine system 10, the turbine drive work changes directly depending on the fuel flow rate, which improves the responsiveness of the supercharging. Also, in a mixed combustion system of diesel fuel and liquefied gas fuel, it is common to increase the proportion of liquefied gas fuel as the load increases, and in this configuration, the supercharging pressure can be increased as the load increases.

[0049] Furthermore, in the internal combustion engine system 10, the regulator 22 controls the fuel pressure so that the fuel pressure of the gaseous fuel supplied to the internal combustion engine 30 is higher than the supercharging pressure in the supercharger 40. As a result, it becomes possible to supply fuel 13 to the internal combustion engine 30 regardless of the supercharging pressure in the supercharger 40.

[0050] Furthermore, in the internal combustion engine system 10, the supply pump 14 can control the supply pressure to the heat exchanger 16 according to the required boost pressure in the supercharger 40. This allows the supply pressure to the heat exchanger 16 to be increased when the required boost pressure is high. As a result, when the expansion work in the turbine 18 is increased, that is, when the boost pressure is increased, the inlet pressure of the turbine 18 can be increased, thereby suppressing the fuel from turning into wet vapor after expansion.

[0051] <Modified example having a bypass channel 60> This modified configuration, as shown in Figure 3, includes a bypass channel 60 that directs a portion of the superheated steam of the fuel 13 generated in the heat exchanger 16 to bypass the turbine 18. The bypass channel 60 is equipped with a control valve 62 that adjusts the flow rate of the fuel 13 flowing into the bypass channel 60.

[0052] In this configuration, the flow rate of fuel 13 passing through the turbine 18 can be increased or decreased by increasing or decreasing the flow rate of fuel 13 flowing into the bypass passage 60, thereby making it possible to adjust the boost pressure. As a result, it becomes possible to adjust the boost pressure in the turbocharger 40 regardless of the amount of fuel 13 consumed by the internal combustion engine 30.

[0053] <Modified example with adjustment valve 70> This modified version, as shown in Figure 4, includes a control valve 70 that adjusts the flow rate of air sent from the compressor 42 to the internal combustion engine 30 according to the required boost pressure in the supercharger 40. The control valve 70 is located downstream of the compressor 42 and upstream of the intercooler 44. For example, when the required boost pressure in the supercharger 40 is low, the control valve 70 can be opened wider to release air into the atmosphere.

[0054] This configuration makes it possible to adjust the boost pressure in the supercharger 40 regardless of the amount of fuel 13 consumed by the internal combustion engine 30.

[0055] <Modified example with generator 80> This modified example, as shown in Figure 5, has a generator 80 that generates electricity using the driving force of the turbine 18 and whose power generation load can be controlled according to the supercharger pressure required by the supercharger 40. In the generator 80, for example, if the supercharger pressure required by the supercharger 40 is low, the power generation load is increased to absorb the work done by the turbine 18. This makes it possible to reduce the supercharger pressure in the supercharger 40.

[0056] This configuration makes it possible to adjust the boost pressure in the supercharger 40 regardless of the amount of fuel 13 consumed by the internal combustion engine 30. Furthermore, the generator 80 may assist in driving the compressor 42 when the boost pressure in the supercharger 40 is insufficient.

[0057] <Modified example having a vaporizer 90> This modified configuration, as shown in Figure 6, includes a vaporizer 90 positioned between the fuel tank 12 and the heat exchanger 16, which vaporizes the fuel 13 from the fuel tank 12 through heat exchange with the cooling water of the internal combustion engine. In this modified configuration, a portion of the fuel 13 from the fuel tank 12 can be vaporized in the vaporizer 90, and the remainder can be vaporized in the heat exchanger 16. Alternatively, in this modified configuration, the entire amount of fuel 13 from the fuel tank 12 can be vaporized in the vaporizer 90, and the vaporized fuel 13 can be further heated in the heat exchanger 16 to generate superheated steam.

[0058] In this modified example, by adding the vaporizer 90, it becomes possible to recover waste heat not only from the exhaust gas but also from the cooling water, thereby improving thermal efficiency. Furthermore, even when the exhaust temperature is low, such as during cold starts, heat exchange with a liquid, which has a larger heat capacity than a gas, becomes possible, allowing for the vaporization of the starting fuel.

[0059] The present invention is not limited to the embodiments described above, and various modifications, changes, and improvements are possible without departing from the spirit of the invention. For example, the modified forms shown above may be combined in any way.

[0060] Furthermore, the following additional information is disclosed. (Note 1) A tank for storing liquefied gaseous fuel, A heat exchanger that heats gaseous fuel from the aforementioned tank by heat exchange with exhaust gas to generate superheated steam, A supercharger comprising a turbine driven by superheated steam of gaseous fuel generated in the heat exchanger, and a compressor that pressurizes air supplied to an internal combustion engine using the driving force of the turbine, The gaseous fuel after driving the turbine is supplied together with pressurized air from the compressor to an internal combustion engine that discharges the exhaust gas, An internal combustion engine system equipped with the following features. (Note 2) A supply pump that supplies the gas fuel from the tank to the heat exchanger and controls the supply pressure to the heat exchanger according to the supercharging pressure required by the supercharger, An internal combustion engine system as described in Appendix 1, comprising: (Note 3) A bypass channel is provided to direct a portion of the superheated steam of the gaseous fuel generated in the heat exchanger to bypass the turbine, A control valve for adjusting the flow rate of gas fuel into the bypass channel, An internal combustion engine system as described in Appendix 1 or Appendix 2, comprising: (Note 4) A control valve adjusts the flow rate of air sent from the compressor to the internal combustion engine in accordance with the required supercharging pressure in the supercharger. An internal combustion engine system described in any one of the appendices 1 to 3, comprising the features specified above. (Note 5) A generator that generates electricity using the driving force of the turbine and whose power generation load can be controlled according to the supercharger pressure required by the supercharger, An internal combustion engine system described in any one of the appendices 1 to 4, comprising the features specified above. (Note 6) A control unit that controls at least one of the fuel pressure and the supercharger pressure such that the fuel pressure of the gaseous fuel supplied to the internal combustion engine is higher than the supercharger pressure in the supercharger. An internal combustion engine system described in any one of the appendices 1 to 5, comprising the features specified above. (Note 7) A vaporizer is positioned between the tank and the heat exchanger, and vaporizes the gaseous fuel from the tank through heat exchange with the cooling water of the internal combustion engine. An internal combustion engine system described in any one of the appendices 1 to 6, comprising the features specified above. [Explanation of symbols]

[0061] 10 Internal Combustion Engine Systems 12 fuel tanks 13. Liquefied gas fuel 14. Supply pump 16 Heat exchanger 18 Turbine 22 Regulators 24 Injectors 30 Internal Combustion Engines 32 Intake pipe 34 Exhaust pipe 38 Exhaust purifying medium 40 Supercharger 42 Compressor 44 Intercooler 46 Throttle 60 Detour flow path 62 Control valve 70 Adjustment valve 80 Generators 90 Vaporizer

Claims

1. A tank for storing liquefied gaseous fuel, A heat exchanger that heats gaseous fuel from the aforementioned tank through heat exchange with exhaust gas to generate superheated steam, A supercharger comprising a turbine driven by superheated steam of gaseous fuel generated in the heat exchanger, and a compressor that pressurizes the air supplied to the internal combustion engine using the driving force of the turbine, The gaseous fuel after driving the turbine is supplied together with pressurized air from the compressor to an internal combustion engine that discharges the exhaust gas, An internal combustion engine system equipped with the following features.

2. A supply pump that supplies the gas fuel from the tank to the heat exchanger and controls the supply pressure to the heat exchanger according to the supercharging pressure required by the supercharger, The internal combustion engine system according to claim 1, comprising:

3. A bypass channel is provided to direct a portion of the superheated steam of the gaseous fuel generated in the heat exchanger to bypass the turbine, A control valve for adjusting the flow rate of gas fuel into the bypass channel, The internal combustion engine system according to claim 1, comprising:

4. A control valve adjusts the flow rate of air sent from the compressor to the internal combustion engine in accordance with the required supercharging pressure in the supercharger. The internal combustion engine system according to claim 1, comprising:

5. A generator that generates electricity using the driving force of the turbine and whose power generation load can be controlled according to the supercharger pressure required by the supercharger, The internal combustion engine system according to claim 1, comprising:

6. A control unit that controls at least one of the fuel pressure and the supercharger pressure such that the fuel pressure of the gaseous fuel supplied to the internal combustion engine is higher than the supercharger pressure in the supercharger. The internal combustion engine system according to claim 1, comprising:

7. A vaporizer is positioned between the tank and the heat exchanger, and vaporizes the gaseous fuel from the tank through heat exchange with the cooling water of the internal combustion engine. The internal combustion engine system according to claim 1, comprising:

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