Methods for improving engine combustion

Abstract

This invention provides an engine operation method that optimizes the amount of hydrogen gas added to the intake air of an engine with a constant rotational speed. [Solution] The amount of fuel to be added is calculated based on the propeller pitch of the variable-pitch propeller, the engine output, or the engine characteristics corresponding to the determined power generation. The optimal amount of hydrogen gas or a mixture of hydrogen gas and oxygen gas to be added to this fuel amount is then calculated. The amount of electrolytic electricity required to generate the calculated amount of gas is supplied to the electrolytic gas generator, and the generated gas is added to the air supplied to the engine.

Description

Technical Field

[0005] , ,

[0001] The present invention relates to a method for improving the combustion of an engine by adding a trace amount of hydrogen gas to the intake air.

Background Art

[0002] The inventors have proposed in Patent Document 1 to add a trace amount (0.01 to 0.1 vol%) of hydrogen to the intake air as a method for efficiently burning a high molecular liquid fuel such as gasoline, diesel or heavy oil in an engine. In addition, the inventors have made the following proposals on the premise of adding a trace amount of hydrogen to the intake air.

[0003] Patent Document 2 discloses that a hydrogen gas supply system includes a hydrogen gas generator that electrolyzes pure water to generate hydrogen gas (oxygen gas) and a hydrogen storage alloy cylinder (canister) filled with a hydrogen storage alloy. The hydrogen gas generated by the hydrogen gas generator is supplied to the intake air line 7 (including the supercharger) via the main line (pipe). A sub-line for supplying the hydrogen gas in the hydrogen storage alloy cylinder to the main line is connected to the main line. Pressure regulating valves are provided in the main line and the sub-line. A signal related to the engine speed is sent from the governor to the control device, and a signal corresponding to the valve opening degree for supplying an amount of added hydrogen according to the load state of the engine is sent from this control device to the pressure regulating valve.

[0004] Patent Document 3 discloses that a signal corresponding to the engine speed is sent from a governor provided to keep the engine speed within a certain range to the control device, and a signal for supplying a hydrogen gas amount within the range below the explosion limit and corresponding to the load applied to the engine is sent from the control device that receives this signal to an adjustment valve provided in the intake air line.

[0005] Patent Document 4 discloses that hydrogen gas supplied to the cylinder simultaneously with fuel gas ignites at the same time as ammonia gas ignites, and because the flame propagation speed of hydrogen gas (relative movement speed of the flame surface) is extremely fast compared to ammonia gas, the movement of the hydrogen gas flame surface promotes mixing of ammonia gas and air in the cylinder, thereby accelerating the complete combustion of ammonia gas. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6328186 [Patent Document 2] Patent No. 6825150 [Patent Document 3] Patent No. 7479603 [Patent Document 4] Patent No. 7079890 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The engines described in the aforementioned prior literature vary their rotational speed according to the load. On the other hand, some engines used in ships and generators have their rotational speed controlled to a constant level.

[0008] In conventional systems, the amount of hydrogen gas (a mixture of hydrogen and oxygen) added to the intake air is supplied in such a way that the hydrogen gas concentration in the intake air remains constant, for example, at 0.1%. Therefore, the amount of hydrogen gas added increases or decreases in proportion to the engine speed.

[0009] In contrast, in an engine with a constantly controlled rotational speed, the amount of fuel supplied to the engine, i.e., the fuel concentration in the intake air, is changed according to the load. If the amount of hydrogen gas added to such an engine with a constantly controlled rotational speed is controlled in proportion to the rotational speed, as in the past, there are cases where the effect of hydrogen gas addition (complete combustion) cannot be achieved. [Means for solving the problem]

[0010] To solve the above problems, the engine operation method according to the present invention adds hydrogen gas or a mixture of hydrogen gas and oxygen gas to the air supplied to an engine whose rotational speed is controlled to a constant level. The optimal amount of hydrogen gas or a mixture of hydrogen gas and oxygen gas to be added is calculated from the propeller pitch of a determined variable-pitch propeller and the amount of air supplied that corresponds to the amount of fuel input corresponding to the required engine output or generated power. The electrolysis current necessary to generate the calculated amount of gas to be added is supplied to an electrolysis gas generator, and the generated gas is added to the air supplied to the engine.

[0011] A governor is generally used to control the amount of fuel supplied to the engine in accordance with the load applied to the engine, thereby keeping the engine speed within a certain range. Instead of the governor, engine output or power generation can also be used as an indicator of the amount of fuel being supplied.

[0012] In the above, the mixed gas of hydrogen and oxygen means that both hydrogen and oxygen gas, which are generated during the electrolysis of water, are supplied to the air supply. [Effects of the Invention]

[0013] According to the present invention, even for an engine with a constant rotational speed, hydrogen gas (a mixture of hydrogen gas and oxygen gas) can be supplied to the intake air in an optimal ratio according to the load.

[0014] As a result, complete combustion can be expected even with load fluctuations in an engine with a constant rotational speed. [Brief explanation of the drawing]

[0015] [Figure 1] A diagram illustrating the engine operation method according to the present invention. [Figure 2] A diagram illustrating another embodiment. [Figure 3] A diagram illustrating another embodiment. [Figure 4] A diagram illustrating another embodiment. [Figure 5] Figure for explaining another embodiment

Embodiments for Carrying out the Invention

[0016] Embodiments of the present invention will be described below based on the accompanying drawings. The method for operating an engine according to the present invention is preferably applied to a variable pitch propeller marine engine, a generator engine, or an electric propulsion marine engine.

[0017] In the case of a variable pitch propeller ship, the speed of the ship is changed by changing the propeller pitch. In this case, since the engine load changes depending on the size of the propeller pitch, the governor controls the fuel injection amount so that the rotational speed of the engine remains constant. Also in the case of a generator engine and an electric propulsion ship, the governor controls the fuel injection amount so that the rotational speed of the engine remains constant according to the power load.

[0018] As shown in FIG. 1, in the present invention, based on any one of the propeller pitch, engine output, or generated power, an air supply amount corresponding to the fuel injection amount determined by the characteristics of the corresponding engine is calculated.

[0019] The characteristics of the engine are the air supply amount corresponding to the fuel injection amount for the engine output according to the load under a constant rotational speed.

[0020] Next, the supply amount (added gas amount) of hydrogen gas (mixed gas of hydrogen gas and oxygen gas) into the air supply corresponding to the air supply amount calculated above is calculated. As the output required by the engine increases, the fuel ratio in the air supply also increases, and the added amount of hydrogen gas (mixed gas of hydrogen gas and oxygen gas) also increases together with the air supply amount for completely burning the increased fuel.

[0021] Then, the amount of hydrogen gas to be added (a mixture of hydrogen and oxygen gas) is calculated, and the electrolytic current required to generate this amount in the electrolyzer is determined. The necessary amount of hydrogen and oxygen gas is then generated in the electrolyzer. Either the generated hydrogen gas alone, or the mixture of generated hydrogen and oxygen gas, is added to the intake air supplied to the engine.

[0022] Figure 2 illustrates another embodiment. In this embodiment, the main engine, whose speed is changed by rotational speed, and the auxiliary engine for power generation, which operates at a constant rotational speed, are controlled by separate systems. For the main engine, the amount of hydrogen gas added is determined according to the engine speed, as in the conventional method.

[0023] For auxiliary engines for generators with a constant rotational speed, the operating method according to the present invention is applied to calculate the amount of fuel to be input corresponding to the required power generation, calculate the amount of additive gas corresponding to this fuel input, and supply the current necessary to generate this amount of additive gas to the electrolyzer.

[0024] Figure 3 illustrates yet another embodiment, in which the amount of added gas is determined according to the rotational speed of the main engine with variable rotational speed, and the amount of added gas is determined according to the required power generation for the auxiliary engine with constant rotational speed. The amount of added gas to the main engine and the amount of added gas to the auxiliary engine are added together, and the total amount of added gas is generated in an electrolyzer. Furthermore, the amount of the generated added gas supplied to the main engine is controlled by a flow control valve.

[0025] The reason for controlling the amount supplied to the main engine with a flow control valve, as described above, is to prevent excessive additive gas from being supplied to the main engine.

[0026] In the embodiment shown in Figure 4, similar to Figure 2, the main engine, whose speed is changed by rotational speed, and the auxiliary engine for power generation, which operates at a constant rotational speed, are controlled by separate systems. For the main engine, the amount of hydrogen gas added is determined according to the propeller pitch, and for the auxiliary engine, the amount of hydrogen gas added is determined according to the required power generation.

[0027] In the embodiment shown in Figure 5, which is a variation of the embodiment shown in Figure 4, the amount of hydrogen gas added is totaled according to the propeller pitch and the power generated, the total amount of added gas is generated in an electrolyzer, and the amount of the generated added gas supplied to the main engine is controlled by a flow control valve.

Claims

[Claim 1] An engine operation method characterized by adding hydrogen gas or a mixture of hydrogen gas and oxygen gas to the air supply to an engine whose rotational speed is controlled to a constant level, by calculating the amount of fuel to be added, which is determined by the propeller pitch of a determined variable-pitch propeller, the determined engine output, or the characteristics of the engine corresponding to the determined power generation, calculating the optimal amount of hydrogen gas or a mixture of hydrogen gas and oxygen gas to be added to this amount of fuel, supplying the amount of electrolysis current necessary to generate the calculated amount of gas to an electrolysis gas generator, and adding the generated gas to the air supply to the engine.

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