JP7236407B2 - Internal combustion engine using hydrogen fuel - Google Patents

Description

The present invention relates to an internal combustion engine using hydrogen fuel.

In recent years, there has been a demand for clean energy sources from the viewpoint of environmental conservation. From this point of view, the development and popularization of internal combustion engines using hydrocarbon-based gas fuel, which uses hydrocarbon-based gas fuel such as natural gas as the main fuel, are rapidly progressing (see, for example, Patent Document 1).

However, the internal combustion engine using this hydrocarbon-based gas fuel has the problem of emitting a large amount of carbon dioxide, as with the conventional petroleum-based fuel such as heavy oil. In addition, since combustion is basically performed in the same heat cycle as a diesel engine, there is also the problem of generating nitrogen oxides. Therefore, from the viewpoint of environmental conservation, the development of internal combustion engines using fuels that are more suitable for environmental conservation than hydrocarbon gas fuels is expected.

In order to meet this demand, an internal combustion engine using hydrogen fuel with light oil as the main fuel has been disclosed (see, for example, Patent Document 2).

JP 2015-190328 A JP 2009-216041 A

However, the above-mentioned internal combustion engine using hydrogen fuel whose main fuel is light oil relates to a small four-cycle diesel engine for automobiles with a relatively high rotational speed. Cycle uniflow diesel engines have extremely low rotational speeds, whereas hydrogen fuel ignites and burns at extremely high speeds, causing abnormal combustion due to premature ignition, etc., and the above-mentioned knocking is seen as a problem. As compared with an internal combustion engine using a hydrocarbon-based gas fuel, the occurrence of knocking is more pronounced, which is a critical problem for an internal combustion engine.

Therefore, the invention of the small 4-cycle diesel engine cannot be easily applied to the low-speed 2-cycle uniflow diesel engine, which is a completely different type of internal combustion engine, and an internal combustion engine using hydrogen fuel is realized. Further breakthroughs are needed to achieve this.

The present invention has been made to solve such problems, and in particular, in order to reduce the amount of carbon dioxide emissions, hydrogen fuel that does not generate carbon dioxide at all is used for low-speed two-cycle uniflow internal combustion engines. An object of the present invention is to provide a hydrogen-fueled internal combustion engine that can be used as a fuel.

In order to solve the above problems, the means adopted by the internal combustion engine using hydrogen fuel of the present invention is a low-speed two-cycle uniflow diesel engine having a scavenging port in the lower part of the cylinder and an exhaust valve in the cylinder head. a hydrogen fuel injection valve for injecting hydrogen fuel disposed in the middle region of the cylinder; a hydrogen fuel supply device for supplying hydrogen fuel to the hydrogen fuel injection valve; and a cylinder head for injecting petroleum-based fuel. a petroleum-based fuel injection valve, a petroleum-based fuel supply device that supplies the petroleum-based fuel to the petroleum-based fuel injection valve, and a controller that controls operations of the hydrogen fuel supply device and the petroleum-based fuel supply device, wherein the controller sets the injection amount ratio of hydrogen fuel and petroleum fuel to 1: (0.5 to 2.0) in terms of energy ratio, and controls the hydrogen fuel supply device so that the piston rises from the bottom dead center in the scavenging stroke. Hydrogen fuel is injected into the cylinder from the hydrogen fuel injection valve at a predetermined time immediately after the scavenging port is closed, and the petroleum fuel is injected when the piston approaches the top dead center in the scavenging stroke by controlling the petroleum fuel supply device. To inject petroleum-based fuel from a valve into a cylinder.

Thus, in a low-speed two-cycle uniflow diesel engine having a scavenging port in the lower part of the cylinder and an exhaust valve in the cylinder head, the hydrogen fuel supply device is controlled to raise the piston from the bottom dead center in the scavenging stroke. At a predetermined time immediately after the scavenging port is closed, hydrogen fuel is injected into the cylinder from a hydrogen fuel injection valve disposed in the central region of the cylinder, and the petroleum-based fuel supply device is controlled so that the piston approaches the top dead center. When the petroleum-based fuel is injected into the cylinder from the petroleum-based fuel injection valve provided in the cylinder head, the injected petroleum-based fuel is ignited, thereby igniting the hydrogen fuel, which burns at an extremely high speed. After the fuel is burned, the petroleum-based fuel continues to burn, so that the internal combustion engine can be operated smoothly without causing abnormal combustion such as knocking.

As a result, a portion of the conventional petroleum-based fuel can be replaced with hydrogen fuel for combustion, and the generation of carbon dioxide can be greatly reduced.

In the internal combustion engine using hydrogen fuel, the predetermined timing is set between immediately before the piston rises from the bottom dead center and closing the scavenging port to immediately after the exhaust valve is closed under the control of the controller . is desirable.

In this way, the predetermined timing for injecting the hydrogen fuel from the hydrogen fuel injection valve into the cylinder can be set from immediately before the piston rises from the bottom dead center and closing the scavenging port to immediately after the exhaust valve is closed under the control of the controller . By setting the predetermined timing between , it is possible to almost completely prevent the hydrogen fuel injected into the cylinder from flowing out from the exhaust valve whose closing timing is set mainly from the heat cycle. can be very evenly distributed in the cylinder. The injection timing of the hydrogen fuel is an extremely important factor for efficient combustion of the hydrogen fuel in the present invention.

The above internal combustion engine using hydrogen fuel further includes an EGR device that is controlled by a controller and circulates exhaust gas discharged from the exhaust valve into scavenging air, and the controller controls the EGR device to reduce the oxygen concentration in the scavenging air. It is desirable to

In this way, by further providing an EGR device (exhaust gas recirculation device), the oxygen concentration in the scavenging air can be reduced, thereby optimally adjusting the hydrogen oxygen concentration after the hydrogen fuel injection, so that the hydrogen fuel can be used. Explosive combustion can be suppressed, thereby further reducing the occurrence of abnormal combustion such as knocking in a low-speed internal combustion engine.

As described above, in a low-speed two-cycle uniflow internal combustion engine using hydrogen fuel, combustion is performed using an EGR device that is usually used for the purpose of reducing the amount of nitrogen oxide emissions by preventing the combustion temperature from rising. The invention that optimally adjusts the hydrogen oxygen concentration of the hydrogen fuel to prevent premature ignition of the hydrogen fuel and prevent abnormal combustion such as knocking is completely unheard of in the prior art. It is a breakthrough for internal combustion engines that use fuel.

In the internal combustion engine using the hydrogen fuel, it is desirable to ignite and burn the hydrogen fuel in the cylinder by injecting the petroleum-based fuel from the petroleum-based fuel injection valve.

Hydrogen fuel is highly ignitable and can be self-ignited only by compression by a piston. However, in this case, the ignition timing varies, and there is a possibility that abnormal combustion may occur due to premature ignition or the like. Therefore, by igniting and burning the hydrogen fuel in the cylinder by the injection of the petroleum-based fuel from the petroleum-based fuel injection valve, the operation is reliably controlled by the controller. By using fuel injection as an ignition source, the ignition timing of the hydrogen fuel can be freely controlled.

In this way, by igniting and burning the hydrogen fuel in the cylinder by injecting the petroleum-based fuel from the petroleum-based fuel injection valve, the conventional internal combustion engine using only petroleum-based fuel and the hydrocarbon system It is possible to eliminate the pilot fuel injection valve and the pilot fuel supply device for igniting the fuel, which are necessary for gas injection engines that use only gas fuel, and to simplify the system and reduce costs. can.

This ignition method by injection of petroleum fuel makes it possible to freely control the ignition timing of hydrogen fuel, which could not be controlled by compression ignition alone, while making full use of the characteristics of hydrogen fuel, which is extremely ignitable. A breakthrough is expected.

In the above internal combustion engine using hydrogen fuel, the injection amount ratio of hydrogen fuel and petroleum-based fuel is preferably 1:(0.5 to 2.0) in terms of energy ratio during steady operation.

The injection amount ratio between hydrogen fuel and petroleum fuel is an extremely important factor for preventing abnormal combustion such as knocking caused by using hydrogen fuel. To achieve an internal combustion engine using hydrogen fuel without causing abnormal combustion such as knocking by setting the injection ratio to 1: (0.5 to 2.0) as an energy ratio during steady operation. can be done.

The internal combustion engine using hydrogen fuel according to the present invention is a low-speed two-cycle uniflow diesel engine having a scavenging port in the lower part of the cylinder and an exhaust valve in the cylinder head. a hydrogen fuel injection valve that injects a hydrogen fuel, a hydrogen fuel supply device that supplies hydrogen fuel to the hydrogen fuel injection valve, a petroleum fuel injection valve that is disposed in the cylinder head and injects petroleum fuel, and the petroleum fuel injection A petroleum-based fuel supply device that supplies the petroleum-based fuel to the valve, and a controller that controls the operation of the hydrogen fuel supply device and the petroleum-based fuel supply device, wherein the controller controls the injection amount ratio between the hydrogen fuel and the petroleum-based fuel. with an energy ratio of 1: (0.5 to 2.0), the hydrogen fuel supply device is controlled to supply hydrogen fuel at a predetermined time immediately after the piston rises from the bottom dead center and closes the scavenging port in the scavenging stroke. The hydrogen fuel injection valve is injected into the cylinder, and the petroleum-based fuel supply device is controlled to inject the petroleum-based fuel into the cylinder from the petroleum-based fuel injection valve when the piston approaches the top dead center in the scavenging stroke.

Therefore, in particular, in order to reduce carbon dioxide generation, it is possible to use hydrogen fuel that does not generate carbon dioxide at all for a two-cycle uniflow internal combustion engine.

1 is a simplified longitudinal sectional view showing a state in which a piston of an internal combustion engine using hydrogen fuel according to the present invention is at bottom dead center; FIG. FIG. 2 is an overall system diagram of the internal combustion engine using the hydrogen fuel of FIG. 1; FIG. 2 is a system diagram showing the control of the controller of the internal combustion engine using the hydrogen fuel of FIG. 1; FIG. 11 is a simplified vertical cross-sectional view showing another embodiment;

DETAILED DESCRIPTION OF THE INVENTION Embodiments for implementing an internal combustion engine using hydrogen fuel according to the present invention will be described in detail with reference to FIGS. 1 to 4. FIG.

As shown in FIG. 1, reference numeral 2 denotes a cylinder of a marine low-speed two-cycle uniflow diesel engine (two-cycle uniflow internal combustion engine) 1, 3 a cylinder head, 4 a piston that slides up and down in the cylinder 2, 5 is an exhaust valve provided in the cylinder head 3 for exhausting combustion gas in the cylinder 2 into an exhaust receiver 5b which will be described later.

As shown in FIG. 2, the operation of the exhaust valve 5 is controlled by an exhaust valve operation controller 5a. The cylinder 2 mentioned above is formed in the inner cylindrical space. A cylinder liner (not shown) is generally provided in the cylinder 2 for smooth sliding with the piston 4. Let's call it 2.

As shown in FIG. 1, the cylinder head 3 is provided with a petroleum-based fuel injection valve 6 for injecting a petroleum-based fuel such as heavy oil as the main fuel in the cylinder 2 toward the piston 4 (downward in the drawing). As shown in FIG. 2 , the petroleum-based fuel is supplied to the petroleum-based fuel injection valve 6 from the petroleum-based fuel supply device 7 .

As shown in FIG. 1, in the middle region of the cylinder 2, for example, within the range of 30 to 70% from the bottom dead center side of the length L (full stroke) of the cylinder 2 from the bottom dead center to the top dead center of the piston 4 , a hydrogen fuel injection valve 8 for injecting hydrogen fuel into the cylinder 2 substantially horizontally with respect to the cylinder axis. As shown in FIG. 2 , the hydrogen fuel injection valve 8 is supplied with hydrogen fuel from a hydrogen fuel supply device 9 .

Hydrogen pipes for supplying hydrogen fuel are all double pipes in consideration of safety. Further, the pressure of hydrogen supplied from the hydrogen fuel supply device 9 to the hydrogen fuel injection valve 8 is set to approximately 1 to 2 MPa. The hydrogen fuel supply device 9 is provided with a safety mechanism (not shown) that prevents the hydrogen fuel from being injected outside the injection timing of the hydrogen fuel.

As shown in FIG. 1, a scavenging port 10 that guides scavenging air into the cylinder 2 is provided below the cylinder 2 and closer to the bottom dead center than the hydrogen fuel injection valve 8 described above. As shown in FIG. 2, part of the exhaust gas discharged to the exhaust receiver 5b passes through an EGR device (exhaust gas recirculation device) 11 into a scavenging pipe 13 for supplying scavenging air to a scavenging port 10. returned.

That is, EGR devices have traditionally been used to reduce the combustion temperature of internal combustion engines to reduce the formation of nitrogen oxides generated by high temperature combustion. The EGR device 11 optimally adjusts the oxygen concentration in the scavenging air to prevent abnormal combustion such as knocking, which is peculiar to hydrogen fuel.

As a result, an unprecedented breakthrough can be achieved in the internal combustion engine using hydrogen fuel. However, the EGR device 11 is also used as a device for reducing the nitrogen oxides generated during the combustion of the petroleum-based fuel as in the conventional case.

As shown in FIG. 3, a controller 12 controls the operations of the petroleum-based fuel supply device 7, the hydrogen fuel supply device 9, the exhaust valve actuation control device 5a, and the EGR device 11 described above.

The operation of the internal combustion engine using the hydrogen fuel of the present invention will be described with reference to FIG. Under the control of the controller 12, the piston 4 first begins to descend from the top dead center, and then the exhaust valve 5 is opened after the piston 4 passes through the middle point of the full stroke L described above. As a result, the exhaust gas burned in the previous cycle is discharged through the exhaust valve 5 into the exhaust receiver 5b.

When the piston 4 descends inside the cylinder 2 and passes through the scavenging port 10 , new air (scavenging air) flows into the cylinder 2 through the scavenging port 10 . In the scavenging stroke, when the piston 4 passes through the bottom dead center, rises again, and passes through the scavenging port 10, the scavenging port 10 is closed by the piston 4, and the controller 12 causes the exhaust valve 5 to open immediately before the scavenging port 10 closes. The hydrogen fuel injection valve 8 is opened at a predetermined time until immediately after it is closed, and the hydrogen fuel supplied from the hydrogen fuel supply device 9 is injected into the cylinder 2 in a substantially horizontal direction with respect to the cylinder axis. , the valve closes after injecting the required amount of hydrogen fuel.

In this way, the timing of injecting the hydrogen fuel from the hydrogen fuel injection valve 8 into the cylinder 2 is set immediately before the piston 4 rises from the bottom dead center and the scavenging port 10 is closed. By setting the predetermined timing to immediately after the injection, it is possible to almost completely prevent the hydrogen fuel injected into the cylinder 2 from flowing out from the exhaust valve 5 whose closing timing is set mainly from the thermal cycle. In addition, the hydrogen fuel can be evenly distributed within the cylinder 2 . This is an extremely important factor for efficient combustion of hydrogen fuel in the present invention.

Then, the controller 12 causes the petroleum-based fuel injection valve 6 to inject the petroleum-based fuel into the cylinder 2 when the piston 4 approaches the top dead center in the scavenging stroke. By injecting the petroleum-based fuel from the petroleum-based fuel injection valve 6 into the cylinder 2, the petroleum-based fuel is first ignited. Combustion of hydrogen fuel is extremely rapid compared to conventional petroleum-based fuels and hydrocarbon-based gas fuels, although the oxygen concentration is optimally adjusted by the above-described EGR device if necessary.

Incidentally, hydrogen fuel is highly ignitable and can be self-ignited only by compression by the piston 4, but in this case, ignition timing may vary and abnormal combustion may occur due to premature ignition or the like. Therefore, the hydrogen fuel is ignited and burned by injecting the petroleum fuel into the cylinder 2 from the petroleum fuel injection valve 6 whose injection timing is clearly controlled by the controller 12 . Therefore, the ignition timing of the hydrogen fuel can be freely and reliably controlled by the controller 12 .

Next, following the combustion of the hydrogen fuel described above, the petroleum-based fuel injected from the petroleum-based fuel injection valve 6 is burned. The injection amount of hydrogen fuel per cycle is determined by the hydrogen supply pressure and the opening timing of the hydrogen fuel injection valve 8, but from the viewpoint of reducing carbon dioxide in the exhaust gas, the hydrogen fuel during steady operation The mixing ratio with petroleum fuel should be 1: (0.5 to 2.0) in energy ratio, and 1: (1.0 to 1.2) in energy ratio at 75% load operation. is desirable.

When the energy amount of hydrogen fuel increases with respect to the energy amount of petroleum fuel, abnormal combustion such as knocking due to hydrogen fuel occurs frequently according to the ratio. If the amount of energy is reduced, it becomes difficult to achieve the original purpose of the invention, which is to significantly reduce the amount of carbon dioxide emitted, according to the ratio. Therefore, it is desirable that the mixing amount ratio of the hydrogen fuel and the petroleum-based fuel is within the above range. The mixing ratio of the hydrogen fuel and the petroleum-based fuel is an extremely important factor in realizing the present invention.

Hydrogen fuel burns very quickly, and if the amount of petroleum fuel is minimized and the amount of hydrogen fuel is maximized, the pressure of the combustion gas may become too high, or it may ignite prematurely, resulting in knocking. Abnormal combustion may occur.

In particular, in the above-described internal combustion engine using hydrogen fuel, it is important to prevent the hydrogen fuel that has already been injected into the cylinder 2 from igniting before the petroleum-based fuel is injected. Therefore, the mixing ratio of air, petroleum-based fuel, and hydrogen fuel is 1:(0.5 to 2.0) in energy ratio during steady operation, and 1:(1) in energy ratio during 75% load operation. .0 to 1.2).

Further, as described above, in the internal combustion engine using the hydrogen fuel of the present invention, the EGR device, which is usually used for the purpose of reducing the amount of nitrogen oxide emissions, is used to reduce the oxygen concentration in the scavenging air, Explosive combustion of hydrogen fuel is suppressed by appropriately adjusting the mixture ratio of hydrogen and oxygen concentration, thereby reducing the occurrence of abnormal combustion such as knocking.

Thus, in an internal combustion engine using hydrogen fuel, it is extremely important to appropriately adjust the hydrogen-oxygen concentration ratio in the cylinder 2. This prevents abnormal combustion such as pre-ignition of the hydrogen fuel. and can provide a breakthrough for internal combustion engines using hydrogen fuel.

Another embodiment is shown in FIG. This shows a case where hydrogen fuel is burned together with heavy oil-based petroleum-based fuel in a 4-cycle diesel engine (internal combustion engine) 30, as in the low-speed 2-cycle uniflow diesel engine 1 described above.

In this case, the hydrogen fuel injection valve 32 disposed in the intake pipe 31 pre-injects the hydrogen fuel into the intake air, and the hydrogen fuel mixture introduced into the cylinder 33 is further added to the petroleum-based fuel of the cylinder head 35 . By injecting the petroleum-based fuel from the fuel injection valve 34, the hydrogen fuel in the intake air is first ignited and burned by the injection ignition of the petroleum-based fuel injected into the cylinder 33, followed by the combustion of the petroleum-based fuel. By doing so, the internal combustion engine using hydrogen fuel can be operated without causing abnormal combustion such as knocking.

1 2-cycle uniflow diesel engine 2 cylinder 3 cylinder head 4 piston 5 exhaust valve 5a exhaust valve operation control device 5b exhaust receiver 6 petroleum fuel injection valve 7 petroleum fuel supply device 8 hydrogen fuel injection valve 9 hydrogen fuel supply device 10 scavenging Port 11 EGR device 12 Controller 13 Scavenging pipe 30 4-cycle diesel engine 31 Intake pipe 32 Hydrogen fuel injection valve 33 Cylinder 34 Petroleum fuel injection valve 35 Cylinder head

Claims (4)

A low speed two-stroke uniflow diesel engine (1) having a scavenging port (10) in the lower part of the cylinder (2) and an exhaust valve (5) in the cylinder head (3), located in the middle region of said cylinder. a hydrogen fuel injection valve (8) for injecting hydrogen fuel; a hydrogen fuel supply device (9) for supplying the hydrogen fuel to the hydrogen fuel injection valve; and a cylinder head for injecting petroleum-based fuel. a petroleum-based fuel injection valve (6), a petroleum-based fuel supply device (7) that supplies the petroleum-based fuel to the petroleum-based fuel injection valve, the hydrogen fuel supply device, and the petroleum-based fuel supply device. a controller (12) for controlling the hydrogen fuel supply device with an injection amount ratio of the hydrogen fuel and the petroleum-based fuel set at an energy ratio of 1:(0.5 to 2.0); In the scavenging stroke, the hydrogen fuel is injected from the hydrogen fuel injection valve into the cylinder at a predetermined time immediately after the piston (4) rises from the bottom dead center and the scavenging port is closed. An internal combustion system using hydrogen fuel, characterized in that a supply device is controlled to inject the petroleum-based fuel into the cylinder from the petroleum-based fuel injection valve when the piston approaches top dead center in the scavenging stroke. institution. The predetermined time is a period from immediately before the piston (4) rises from the bottom dead center and closing the scavenging port (10) to immediately after the exhaust valve (5) is closed under the control of the controller (12). 2. The internal combustion engine using hydrogen fuel according to claim 1, characterized in that it is set. It further comprises an EGR device (11) that is controlled by the controller (12) and circulates the exhaust gas discharged from the exhaust valve (5) into scavenging air, wherein the controller controls the EGR device so that the exhaust gas in the scavenging air is circulated. 3. The internal combustion engine using hydrogen fuel according to claim 1 or 2, characterized in that the oxygen concentration is reduced. The hydrogen fuel in the cylinder (2) is ignited and burned by the injection of the petroleum-based fuel from the petroleum-based fuel injection valve (6), according to any one of claims 1 to 3. Internal combustion engine using hydrogen fuel.

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