A method for setting the camshaft valve timing of a hydrogen-rich fuel gas engine

Abstract

This invention discloses a method for setting the camshaft valve timing of a hydrogen-rich gas engine, specifically including the following steps: At the end of the piston's exhaust stroke, when the exhaust valve is open and the piston is pushing the gas in the cylinder upwards for exhaust, the intake valve is opened before the piston reaches top dead center (TDC). Then, the exhaust valve is delayed in closing after the piston has passed TDC and moved a short distance downwards. Next, the intake valve is delayed in closing after the piston has passed bottom dead center and moved a short distance upwards. The crankshaft rotation causes the piston to move upwards, compressing the gas in the cylinder. At the end of the piston's power stroke, the exhaust valve is opened earlier before the piston reaches bottom dead center for early exhaust. This method for setting the camshaft valve timing of a hydrogen-rich gas engine belongs to the field of diesel engine technology. By using early opening or delayed closing to extend the intake and exhaust times, the crankshaft angles corresponding to the actual intake and exhaust strokes of the engine are both greater than 180°, allowing for more complete intake and more thorough exhaust, thereby improving engine power.

Description

Technical Field

[0001] This invention relates to diesel engine technology, and more specifically, to a method for setting the valve timing of a hydrogen-rich gas engine camshaft. Background Technology

[0002] Valve timing refers to the opening and closing times and durations of the intake and exhaust valves, expressed in crankshaft angles, typically using a circular diagram. Since one stroke requires a 180° crankshaft angle, a four-stroke cycle is 720°. Engine scavenging is controlled by the valves, and the valve opening and closing times are expressed in degrees (°) based on crankshaft angles.

[0003] When an engine (gasoline engine) is running, the ignition timing has a significant impact on its performance. Advanced ignition means that the spark plug ignites the combustible mixture in the combustion chamber before the piston reaches top dead center of the compression stroke. The angle through which the crankshaft rotates from the ignition timing to the piston reaching top dead center is called the ignition advance angle. The ignition advance angle that achieves optimal engine power, fuel economy, and emissions is called the optimal ignition advance angle.

[0004] In existing technologies, hydrogen-rich gases such as coke oven gas, semi-coke gas, and alloy tail gas are widely distributed and exist in large quantities in industrial mining and refining fields. However, hydrogen-rich gases pose a serious risk of backfire in internal combustion engines due to their low density, easy escape, and easy ignition. Therefore, it is necessary to design the camshaft profile structure of the engine and adjust the opening and closing times of the intake and exhaust valves by resetting the valve timing. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art. The purpose of the present invention is to provide a method for setting the valve timing of the camshaft of a hydrogen-rich gas engine.

[0006] To achieve the above objectives, the present invention provides a method for setting the camshaft valve timing of a hydrogen-rich gas engine, specifically including the following method: At the end of the piston's exhaust stroke, when the exhaust valve is open and the piston is pushing the gas in the cylinder upwards for exhaust, the intake valve is opened in advance before the piston reaches top dead center. Then, when the piston moves down a short distance past top dead center, the exhaust valve is closed with a delay. Next, when the piston moves up a short distance past bottom dead center, the intake valve is closed with a delay. The crankshaft rotates, causing the piston to move upwards and compress the gas in the cylinder. At the end of the piston's power stroke, the exhaust valve is opened in advance before the piston reaches bottom dead center for early exhaust.

[0007] Furthermore, the angle of crankshaft rotation during the time from the early opening of the intake valve to the piston reaching the top dead center crank position is set as the intake advance angle α1, and the intake advance angle α1 is set to 5°–10°.

[0008] Furthermore, the angle of crankshaft rotation during the time from when the piston reaches the bottom dead center crank position until the intake valve is delayed in closing is set as the intake lag angle α2, and the intake lag angle α2 is set to 10°–20°.

[0009] Furthermore, during the piston's intake stroke, the angle of crankshaft rotation during the time from when the piston moves a short distance past top dead center until the exhaust valve is delayed in closing is set as the exhaust valve lag angle β2, which is set to 10°–20°.

[0010] Furthermore, the crankshaft rotation angle during the time from the early opening of the intake valve to the delayed closing of the exhaust valve is set to be less than 25°, i.e., α1+β2<25°.

[0011] Furthermore, the intake advance angle α1 is set to 5°, the intake lag angle α2 is set to 10°, and the exhaust valve lag angle β2 is set to 10°.

[0012] Furthermore, during the piston's power stroke, the angle of crankshaft rotation during the time from the early opening of the exhaust valve to the piston's downward movement to the bottom dead center crank position is set as the exhaust advance angle β1, which is set to 30°–50°.

[0013] Furthermore, the exhaust advance angle β1 is set to 45°.

[0014] Beneficial effects Compared with the prior art, the beneficial effects of the camshaft valve timing setting method for hydrogen-rich gas engines of the present invention are as follows: The camshaft valve timing setting method of the hydrogen-rich gas engine of the present invention uses the method of opening early or closing late to extend the intake and exhaust time. In this way, the crankshaft rotation angle corresponding to the actual intake and exhaust strokes of the engine is greater than 180°, so as to make the intake more sufficient and the exhaust more thorough, thereby improving the engine power. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the valve timing limit of the camshaft valve timing setting method for the hydrogen-rich gas engine of the present invention. Detailed Implementation

[0016] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0017] The specific implementation of this invention is as follows: like Figure 1 As shown, a method for setting the valve timing of a hydrogen-rich gas engine camshaft involves setting the valve timing cams on the camshaft to drive the opening and closing of the intake and exhaust valves. The arrangement angle of each valve timing cam on the camshaft is related to the crankshaft rotation angle, i.e., it is set according to the valve timing. The opening and closing times of the intake and exhaust valves are determined by the crankshaft angle and the piston's upward and downward positions, thereby determining the valve timing and driving the structure and arrangement position of the valve timing cams. Specifically, the method includes the following steps: at the tail end of the piston's exhaust stroke, when the exhaust valve is in the open state... As the piston pushes the gas in the cylinder upwards to expel the exhaust, the intake valve is opened before the piston reaches top dead center. This is achieved by adjusting the cam angle on the camshaft. Then, the exhaust valve is delayed in closing a short distance after the piston passes top dead center. Next, the intake valve is delayed in closing a short distance after the piston passes bottom dead center. The crankshaft rotation causes the piston to move upwards, compressing the gas in the cylinder. At the end of the power stroke, before the piston reaches bottom dead center, the exhaust valve is opened to expel the exhaust gas.

[0018] In this method of setting the camshaft valve timing for a hydrogen-rich gas engine, the intake valve opens before the piston reaches top dead center, and the exhaust valve closes late after the piston passes top dead center. The overlap angle between the intake valve opening and the exhaust valve closing is less than 25°. This constitutes an asymmetrical small overlap angle opening structure for the intake and exhaust valve timing, where the intake valve opens before the piston approaches top dead center. When the piston slides to the top and exhausts the gas from the cylinder through the exhaust valve, air is simultaneously injected through the intake valve. The newly injected air lowers the temperature of the gas in the cylinder, and the newly injected air, along with the hot gas in the cylinder, is expelled under the piston's pushing force. As the piston slides downward after reaching top dead center, the delayed closing of the exhaust valve further lowers the temperature of the cylinder due to the newly injected air, and some high-temperature, high-pressure gas is expelled through the exhaust valve. The cylinder temperature and pressure are reduced, preventing high-temperature gas from entering the intake manifold through the intake valve. This reduces the probability of backfire caused by high-temperature gas flowing back into the intake manifold when the intake and exhaust valves are in an overlapping opening state.

[0019] In this hydrogen-rich gas engine camshaft valve timing setting method, the intake valve is delayed in closing after the piston passes bottom dead center. This delayed closing time fully utilizes the pressure difference and significant airflow inertia within the cylinder before the intake stroke ends to continue intake. After bottom dead center, as the piston rises, the cylinder pressure gradually increases, and the intake airflow velocity gradually decreases. When the pressure difference between the inside and outside of the cylinder disappears and the flow velocity approaches zero, the intake valve should close. By delaying the intake valve closing, more air is drawn into the cylinder, ensuring complete combustion of the injected fuel, improving combustion efficiency, and maintaining optimal engine operating conditions.

[0020] In this embodiment, the angle of crankshaft rotation during the time from the intake valve opening in advance to the piston reaching the top dead center crank position is set as the intake advance angle α1. The intake advance angle α1 is set to 5°-10°, and the intake valve opens in advance to ensure that the valve has a large opening at the beginning of the intake stroke, which is beneficial to increasing the charging volume.

[0021] In this embodiment, the angle of crankshaft rotation during the time from when the piston reaches the bottom dead center crank position to when the intake valve is delayed in closing is set as the intake lag angle α2. The intake lag angle α2 is set to 10°-20° to prevent excessive intake lag angle α2 from causing intake backflow.

[0022] In this embodiment, during the piston's intake stroke, the angle of crankshaft rotation during the time from when the piston moves a short distance past top dead center to when the exhaust valve is delayed in closing is set as the exhaust valve lag angle β2, and the exhaust valve lag angle β2 is set to 10°–20°.

[0023] In this embodiment, the crankshaft rotation angle during the time from the early opening of the intake valve to the delayed closing of the exhaust valve is set to be less than 25°, i.e., α1+β2<25°.

[0024] In this embodiment, the intake advance angle α1 is set to 5°, the intake lag angle α2 is set to 10°, and the exhaust valve lag angle β2 is set to 10°. That is, both the intake lag angle α2 and the exhaust valve lag angle β2 are set to 10°.

[0025] In this embodiment, during the piston's power stroke, the angle of crankshaft rotation during the time from the early opening of the exhaust valve to the piston's downward movement to the bottom dead center crank position is set as the exhaust advance angle β1, which is set to 30°–50°. Although the early opening of the exhaust valve consumes some power during the power stroke, it allows most of the combustion exhaust gas to be quickly discharged using the higher cylinder pressure. By the time the piston moves upward, the cylinder pressure has dropped significantly, which reduces the power consumed during the exhaust stroke. In addition, the early discharge of high-temperature exhaust gas can also prevent the engine from overheating.

[0026] As attached Figure 1As shown, the crankshaft angle position corresponding to the early opening of the intake valve is set as A, the crankshaft angle position corresponding to the delayed closing of the intake valve is set as B, the crankshaft angle position corresponding to the early opening of the exhaust valve is set as C, and the crankshaft angle position corresponding to the early and delayed closing of the exhaust valve is set as D. The angle of crankshaft rotation during the time from A to B is the intake duration angle α3, the angle of crankshaft rotation during the time from C to D is the exhaust duration angle β3, and the angle of crankshaft rotation during the time from A to D is the valve overlap angle. The exhaust advance angle β1 is set to 45°. The intake duration angle α3 is 195°, and the exhaust duration angle β3 is 235°. In this method of setting the camshaft valve timing for a hydrogen-rich gas engine, the method of early opening or delayed closing is used to extend the intake and exhaust times. In this way, the crankshaft angles corresponding to the actual intake and exhaust strokes of the engine are both greater than 180°, so as to make the intake more sufficient and the exhaust more thorough, thereby improving the engine power.

[0027] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for setting the valve timing phase of a hydrogen-rich gas engine camshaft, characterized in that, Specifically, the methods include the following: At the end of the piston's exhaust stroke, when the exhaust valve is open and the piston is pushing the gas in the cylinder upwards for exhaust, the intake valve is opened before the piston reaches top dead center. Then, the exhaust valve is delayed in closing a short distance after the piston passes top dead center. Next, the intake valve is delayed in closing a short distance after the piston passes bottom dead center, and the crankshaft rotates to compress the gas in the cylinder. At the end of the piston's power stroke, the exhaust valve is opened earlier than the piston is about to reach bottom dead center for early exhaust. The angle of crankshaft rotation during the time from the early opening of the intake valve to the piston reaching the top dead center crank position is set as the intake advance angle α1. The intake advance angle α1 is set to 5°–10°. The angle of crankshaft rotation during the time from reaching the bottom dead center crank position to the delayed closing of the intake valve is set as the intake lag angle α2, which is set to 10°–20°. During the piston's intake stroke, the angle of crankshaft rotation during the time from the piston passing the top dead center and descending a short distance to the delayed closing of the exhaust valve is set as the exhaust valve lag angle β2, which is set to 10°–20°. During the piston's power stroke, the angle of crankshaft rotation during the time from the early opening of the exhaust valve to the piston descending to the bottom dead center crank position is set as the exhaust advance angle β1, which is set to 30°–50°. The angle of crankshaft rotation during the time from the early opening of the intake valve to the delayed closing of the exhaust valve is set to less than 25°, i.e., α1+β2<25°.

2. The method for setting the valve timing of a hydrogen-rich gas engine camshaft according to claim 1, characterized in that, Set the intake advance angle α1 to 5°, the intake lag angle α2 to 10°, and the exhaust valve lag angle β2 to 10°.

3. The method for setting the valve timing of a hydrogen-rich gas engine camshaft according to claim 1, characterized in that, Set the exhaust advance angle β1 to 45°.

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