Die-casting cylinder cap for four-stroke small gasoline engine and manufacturing method thereof

Abstract

The invention relates to a die-casting cylinder cap for a four-stroke small gasoline engine and a manufacturing method thereof. An air intake passage of the die-casting cylinder cap consists of two parts, namely a casting section of the air intake passage and a machining section of the air intake passage; the cross section of the casting section of an air intake and exhaust passage is rectangular, or the upper part of the casting section is rectangular and the lower part of the casting section is semicircular; the casting section of the passage is slowly changed along a central line; the area of the casting section is gradually reduced; the tapered gradient is not more than 3 percent; the maximum width or diameter of the casting section at the junction is equal or approximately equal; the inclination angle alpha between the casting section of the passage and the horizontal direction is more than or equal to 15 degrees; and the depth of the machining section of the air intake passage is 0 to 2mm higher than the intersecting part of the casting section and the machining section. Due to the adoption of the structure, the air intake and exhaust passage has relatively high transmissibility coefficient, high power output of and engine and low fuel oil consumption are realized, and discharged pollutants of a gasoline engine are reduced.

Description

technical field [0001] The invention relates to the field of four-stroke small gasoline engine manufacturing, in particular to a die-casting cylinder head for a four-stroke small gasoline engine and a manufacturing method thereof. Background technique [0002] Small gasoline engines include non-road general-purpose small gasoline engines, motorcycle engines and other low-power gasoline engines. In gasoline engines, when the intake and exhaust passages have a smooth flow area and a large flow coefficient, the intake air volume entering the cylinder per cycle can be increased. , clean exhaust, and improved engine combustion conditions are crucial to the improvement of engine performance. At present, there are many researches on the inlet and exhaust ports of diesel engines with swirling flow in China, but little research on the inlet and exhaust ports of small gasoline engines without swirling flow, especially the flow characteristics of die-casting cylinder heads have not bee...

AI Technical Summary

Problems solved by technology

The cylinder heads of small gasoline engines currently produced in China often only consider the technical requirements in the mold design, and seldom consider the flow characteristics of the air passage of the internal combustion engine. Therefore, the shape of the air passage does not meet the performance requirements of gasoline engines, resulting in some small gasoline engines. Small size and poor performance, such as gasoline engines for vertical shaft lawn mowers produced in China, the problem is particularly prominent due to the long air passage of the cylinder head. After we improved the intake and exhaust passages of a gasoline engine, the power of the gasoline engine increased by nearly 15%. Fuel consumption has dropped by 4.7%, and exhaust emissions have been greatly improved

The direct injection diesel engine organizes the intake vortex, so it is necessary to test the flow characteristics of the air passage on a specially developed test bench. Small gasoline engines do not organize the intake vortex, and generally do not test the flow characteristics of the air passage, which is also the reason why it is difficult to find problems in the air passage.

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