Internal combustion engine

Abstract

To enable energy of ultra-high-pressure fuel, which is compressed and stored in a fuel tank before being supplied to an engine or a fuel cell, to be recovered and recycled when the fuel is supplied to the engine or the fuel cell.SOLUTION: A fuel supply device 6, which supplies fuel containing hydrogen to an engine 100 or a fuel cell generating output by consuming the fuel, comprises: a fuel tank 61 which stores the fuel; fuel piping 62 which allows the fuel discharged from the fuel tank 61 to be distributed to the engine 100 or the fuel cell; and conversion mechanisms 63 and 64 which extract energy of the fuel before being decompressed while reducing pressure of the fuel flowing in the fuel piping 62.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a device for supplying fuel to a prime mover or a fuel cell that consumes a fuel containing hydrogen to generate an output, or an internal combustion engine that is such a prime mover.

Background Art

[0002] Reduction of emissions of carbon dioxide gas having a greenhouse effect has been recognized as a global issue. Recently, attempts have been made to use hydrogen instead of fossil fuels containing carbon as fuel for internal combustion engines that are used as various power sources.

[0003] Hydrogen is a gas under normal temperature and pressure. Therefore, a hydrogen fuel tank stores hydrogen at an ultra-high pressure of about 70 MPa at maximum. Hydrogen discharged from this fuel tank is decompressed and regulated to a predetermined pressure of about 10 MPa to 20 MPa via a pressure regulator, and then supplied to an injector. Then, the fuel injected from the injector is burned in a cylinder to rotationally drive a crankshaft that is an output shaft of the internal combustion engine.

[0004] Unlike a conventional internal combustion engine that pumps gasoline, light oil, etc., which are liquids under normal temperature and pressure, from a tank to an injector by a fuel pump, in an internal combustion engine that discharges ultra-high pressure hydrogen from a tank to an injector, as the hydrogen stored in the tank is consumed, the pressure in the tank, and thus the pressure of the hydrogen supplied to the injector, decreases. A pressure regulator interposed between the hydrogen fuel tank and the injector functions to keep the pressure of the hydrogen supplied to the injector as constant as possible (for the above, for example, refer to the following patent documents).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] Reducing the pressure of the ultra-high-pressure fuel stored in the tank using a pressure regulator before supplying it means that the energy used for high-pressure compression when filling the tank with fuel is being wasted.

[0007] The present invention Internal combustion engine The primary objective is to recover and reuse the energy contained in ultra-high-pressure fuel before it is supplied to the fuel system. [Means for solving the problem]

[0010] The internal combustion engine according to the present invention, which generates output by consuming a hydrogen-containing fuel, comprises a fuel supply device comprising a fuel tank for storing fuel, a fuel pipe for circulating fuel discharged from the fuel tank toward the cylinders, and a conversion mechanism for extracting the energy contained in the fuel before depressurization while reducing the pressure of the fuel flowing through the fuel pipes. The conversion mechanism comprises a turbine rotated by the fuel flowing through the fuel pipes, a wastegate valve or a variable nozzle attached to the turbine for opening and closing the inlet of a bypass passage that bypasses the turbine, and a generator driven by the turbine. Furthermore, a recirculation passage is provided for recirculating fuel leaking from the turbine side to the generator side into an intake passage connected to the cylinders. The intake passage of the internal combustion engine is equipped with a supercharger that supercharges the intake air, and a check valve or ventilation valve is installed on the return passage to prevent backflow of the supercharger from the intake passage toward the generator. [Effects of the Invention]

[0011] According to the present invention, compressed fuel is stored in a fuel tank. Internal combustion engine The energy contained in the ultra-high-pressure fuel before it is supplied, Internal combustion engine This allows for the collection and reuse of the product during supply, contributing to further improvements in efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] A diagram showing the configuration of the prime mover and fuel supply system of one embodiment of the present invention. [Modes for carrying out the invention]

[0013] One embodiment of the present invention will be described with reference to the drawings. Figure 1 shows the configuration of an internal combustion engine 100 for a vehicle, which is the prime mover in this embodiment, and a fuel supply device 6 that supplies fuel to it.

[0014] The internal combustion engine 100 of this embodiment is a direct-injection (direct injection) four-stroke spark-ignition engine mounted as a power source in a vehicle, and has multiple cylinders 1 (one of which is shown in Figure 1). Each cylinder 1 is equipped with an injector 11 for directly injecting fuel into the combustion chamber of that cylinder 1. In addition, a spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 generates a spark discharge between its center electrode and ground electrode upon application of an induced voltage generated by the ignition coil. The ignition coil, together with an igniter which is a semiconductor switching element, is integrally built into the coil case.

[0015] The intake passage 3, which supplies intake air, takes in air from the outside and guides it to the intake port of each cylinder 1. The air cleaner 31, the electronically controlled throttle valve 32 which is an intake throttling valve, the surge tank 33, and the intake manifold 34 are arranged on the intake passage 3 in this order from upstream.

[0016] The exhaust passage 4 for discharging exhaust gases guides the exhaust gases generated as a result of fuel combustion in each cylinder 1 to the outside through the exhaust port of each cylinder 1. An exhaust manifold 42 and an exhaust gas purification device 41 are located on this exhaust passage 4. The exhaust gas purification device 41 includes a three-way catalyst that promotes oxidation / reduction reactions of hydrocarbons, carbon monoxide, and nitrogen oxides, and a selective catalytic reduction device that reduces nitrogen oxides using a reducing agent such as urea water. In addition, an exhaust bypass passage 43 that bypasses the exhaust turbine 52 and a wastegate valve 44, which is a bypass valve that opens and closes the inlet of this bypass passage 43 are provided.

[0017] The exhaust turbocharger 5 is configured such that the exhaust turbine 52 and the compressor impeller 51 are coaxially connected via a shaft 53 and operate in conjunction. The turbine 52 and impeller 51 are rotationally driven using the energy of the exhaust gas flowing through the exhaust passage 4. This rotational force causes the compressor to perform a pumping action, thereby pressurizing and compressing (supercharging) the intake air flowing through the intake passage 3 and sending it to the cylinder 1.

[0018] The internal combustion engine 100 of this embodiment uses a hydrogen-containing fuel (which may be extremely high-purity hydrogen). The fuel tank 61 stores hydrogen fuel that has been compressed to an ultra-high pressure state when filled. The fuel discharged from this fuel tank 61 is sent to the injector 11 via the fuel pipe 62 and injected into the combustion chamber of cylinder 1 when the injector 11 opens.

[0019] A turbine 63 is mounted on the fuel piping 62 from the fuel tank 61 to the injector 11. A generator 64 is coaxially connected to the turbine 63. These turbines 63 and generator 64 are rotationally driven using the ultra-high-pressure fuel flowing through the fuel piping 62. The rotating generator 64 generates electricity. This electricity can be used to charge onboard energy storage devices (such as secondary batteries like lead-acid batteries, lithium-ion batteries, and nickel-metal hydride batteries, or capacitors) or to supply electric motors for the vehicle's propulsion system or electrical loads for the vehicle's electrical system.

[0020] As the fuel discharged from the tank 61 flows through the fuel piping 62 and passes through the turbine 63, the fuel pressure decreases. The fuel pressure downstream of the turbine 63 is lower than the fuel pressure upstream of the turbine 63 and in the tank 61. The turbine 63 and generator 64 act as a conversion mechanism that recovers and reuses at least a portion of the energy contained in the high-pressure fuel before it was depressurized when supplying it to cylinder 1 of the internal combustion engine 100 after depressurizing the high-pressure fuel stored in the tank 61.

[0021] A pressure regulator (not shown) having a function of regulating the pressure of fuel to a predetermined magnitude can be installed at a location downstream of the turbine 63 and upstream of the injector 11 in the fuel pipe 62. However, the pressure regulator for hydrogen fuel is expensive, and if possible, it is desired to eliminate the pressure regulator. When eliminating the pressure regulator, it is necessary to control the rotational speed of the turbine 63, the output of the generator 64, etc. so as to keep the pressure of the fuel passing through the turbine 63 and reaching the injector 11 as constant as possible. A wastegate valve (not shown) for opening and closing the inlet of a bypass passage bypassing the turbine 63 and a variable nozzle (not shown) are attached to the turbine 63, and by opening and closing these wastegates and / or variable nozzles, it becomes possible to increase or decrease and adjust the pressure of the fuel downstream of the turbine 63 and upstream of the injector 11.

[0022] It is also conceivable to install a control valve 65 on the fuel pipe 62 instead of or together with the pressure regulator. The control valve 65 is a flow control valve that can open and close the fuel pipe 62 or increase or decrease and adjust the flow rate of the fuel flowing through the fuel pipe 62. The control valve 65 can serve as a safety valve.

[0023] Sealing is applied to the bearing portion that supports the rotating shaft connecting the turbine 63 and the generator 64, but it cannot be denied that a part of the fuel passing through the turbine 63 may slightly leak from the turbine 63 side to the generator 64 side. Therefore, in the present embodiment, a reflux passage 66 for refluxing the fuel leaked to the generator 64 side to the intake passage 3 of the internal combustion engine 100 is provided. The reflux passage 66 communicates the inside of the generator 64 with the downstream of the throttle valve 32 in the intake passage 3 (particularly, the surge tank 33 or the intake manifold 34). The fuel leaked to the generator 64 side is sucked into the intake passage 3 through the reflux passage 66 and burned in the cylinder 1.

[0024] However, the internal combustion engine of the present embodiment 100 is accompanied by a supercharger 5, and the supercharged air flowing through the intake passage 3 may be significantly increased in pressure. In order to suppress the backflow of the supercharged air from the intake passage 3 toward the generator 4, it is preferable to install a check valve, a ventilation valve, etc. 67 on the reflux passage 66.

[0025] The electronic control unit (Electronic Control Unit) 0 that controls the operation of the internal combustion engine 100 of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, etc. The ECU 0 may be such that a plurality of ECUs or controllers are communicably connected to each other via an electrical communication line such as a CAN (Controller Area Network).

[0026] The input interface of the ECU0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft, which is the output shaft of the internal combustion engine 100, and the engine speed, an accelerator opening signal c output from a sensor that detects the amount the vehicle driver depresses the accelerator pedal as accelerator opening (in other words, the engine load rate or engine torque required for the internal combustion engine 100), an intake air temperature / intake pressure signal d output from an intake air temperature / intake pressure sensor that detects the temperature and pressure of the intake air in the intake passage 3 connected to cylinder 1 (particularly the surge tank 33 or intake manifold 34), and a sensor that detects the coolant temperature of the internal combustion engine 100. The following signals are input: a coolant temperature signal e output from a water temperature sensor; a fuel temperature / fuel pressure signal f output from a fuel temperature / fuel pressure sensor that detects the temperature and pressure of hydrogen fuel in the fuel piping 62 connected to the injector 11 (particularly downstream of the control valve 65 and directly upstream of the injector 11); a gas properties signal g output from sensors that detect the properties of the gas flowing through the exhaust gas purification device 41 in the exhaust passage 4 (including O2 sensors and linear A / F sensors that measure the oxygen concentration in the gas, in other words, the air-fuel ratio, and hydrogen sensors that measure the hydrogen concentration in the gas); and a battery SOC (State of Charge) signal h output from sensors that detect the amount of charge stored in the on-board energy storage device (particularly battery current and / or battery voltage sensors).

[0027] The output interface of the ECU0 outputs an ignition signal i to the igniter of the spark plug 12, a fuel injection signal j to the solenoid of the injector 11, an opening operation signal k to the throttle valve 32, an opening operation signal l to the control valve 65, and an opening operation signal m to the wastegate valve or variable nozzle attached to the turbine 63.

[0028] The ECU0 processor interprets and executes a program pre-stored in memory, calculates operating parameters, and controls the operation of the internal combustion engine 100. The ECU0 acquires various information a, b, c, d, e, f, g, and h necessary for controlling the operation of the internal combustion engine 100 via the input interface, and based on this, determines various operating parameters such as the required fuel injection amount, fuel injection timing (including the number of fuel injections in one cycle of cylinder 1 (in a 4-stroke engine, one cycle consists of the intake stroke, compression stroke, expansion stroke, and exhaust stroke)), fuel injection pressure, ignition timing (including the number of spark ignitions in one cycle of cylinder 1), and power generated by the generator 64 (or output voltage or output current). The ECU0 applies various control signals i, j, k, l, and m corresponding to the operating parameters via the output interface.

[0029] In this embodiment, a fuel supply device 6 for supplying fuel to an internal combustion engine 100, which is a prime mover that generates output by consuming hydrogen-containing fuel, comprises a fuel tank 61 for storing fuel, a fuel pipe 62 for circulating fuel discharged from the fuel tank 61 toward cylinder 1 of the internal combustion engine 100, and a turbine 63 and a generator 64, which are conversion mechanisms that reduce the pressure of the fuel flowing through the fuel pipe 62 while extracting the energy that the fuel contained before depressurization possessed. According to this embodiment, the ultra-high pressure fuel discharged from the fuel tank 61 is reduced to an appropriate pressure and supplied to the internal combustion engine 100, while the energy that the fuel contained before depressurization is recovered and reused in the form of electricity, contributing to further improvement of efficiency.

[0030] Even if the amount of fuel stored in the fuel tank 61 increases or decreases, and the pressure of the fuel discharged from the fuel tank 61 fluctuates, the pressure of the fuel supplied to the injector 11 can be stabilized, allowing the injector 11 to accurately inject the desired amount of fuel. Therefore, the internal combustion engine 100 can be operated stably. It is also possible to eliminate the pressure regulator from the fuel piping 62 between the fuel tank 61 and the injector 11.

[0031] Furthermore, a recirculation passage 66 is provided to return fuel leaking from the turbine 63 to the generator 64 to the intake passage 3 connected to the cylinder 1, allowing the leaked fuel to be burned in the cylinder 1 and preventing waste.

[0032] It should be noted that the present invention is not limited to the embodiments described in detail above. For example, although the internal combustion engine 100 in the above embodiment was of the direct injection type, the present invention may also be applied to a port injection type internal combustion engine in which fuel is injected from an injector towards the intake port of each cylinder.

[0033] Furthermore, in a vehicle equipped with a fuel cell as a power source (Fuel Cell Vehicle), the fuel injection device 6 according to the present invention can also be used to supply fuel to the fuel cell.

[0034] Furthermore, the specific configuration of each part can be modified in various ways without departing from the spirit of the present invention. [Explanation of Symbols]

[0035] 100... Prime mover (internal combustion engine) 1…Cylinder 11…Injector 3…Intake passage 6…Fuel supply device 61…Fuel tank 62…Fuel piping 63, 64… Conversion mechanisms (turbines, generators)

Claims

[Claim 1] An internal combustion engine that generates power by consuming a hydrogen-containing fuel, The fuel supply system comprises a fuel tank for storing fuel, fuel piping for circulating fuel discharged from the fuel tank toward the cylinders, and a conversion mechanism for extracting the energy contained in the fuel before depressurization while reducing the pressure of the fuel flowing through the fuel piping. The conversion mechanism includes a turbine rotated by fuel flowing through the fuel piping, a wastegate valve or a variable nozzle attached to the turbine that opens and closes the inlet of a bypass passage that bypasses the turbine, and a generator driven by the turbine. Furthermore, a recirculation passage is provided to return fuel leaking from the turbine side to the generator side to the intake passage connected to the cylinder. An internal combustion engine having a supercharger attached to the intake passage for supercharging intake air, and a check valve or ventilation valve installed on the return passage to suppress backflow of the supercharger from the intake passage toward the generator.

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