柴油机为什么不装火花塞也能点燃混合气?压燃方式下喷油提前角如何影响燃烧相位与整机表现?
Why does a diesel engine ignite its mixture with no spark plugs at all, and how does injection timing shape combustion phasing and overall behavior in compression ignition?
柴油机将空气压缩到很高的压缩比(通常14至22),缸内温度升到500摄氏度以上,雾化燃油喷入高温高压空气中自行着火,完全不需要火花塞。喷油提前角决定滞燃期长短与放热重心:过早喷油会使压力升高率过大、工作粗暴且NOx排放增多,过晚喷油则后燃加重、排气温度升高、热效率下降。
A diesel engine compresses intake air to a high compression ratio, typically 14 to 22, pushing in-cylinder temperature above about 500 degrees Celsius, so atomized fuel injected into the hot charge autoignites without any spark plug. Injection timing sets the ignition delay and the center of heat release: fuel delivered too early produces an excessive rate of pressure rise, rough running, and higher NOx, while fuel delivered too late intensifies afterburning, raises exhaust temperature, and cuts thermal efficiency.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
John B. Heywood著《Internal Combustion Engine Fundamentals》(McGraw-Hill,2018年第2版)第10章柴油机燃烧
John B. Heywood, Internal Combustion Engine Fundamentals, 2nd ed., McGraw-Hill, 2018, Chapter 10 on diesel engine combustion.
独立核验依据 · Independent verification: 核验依据 1 ISBN 9781260116106 (2018)
#内燃机 #压燃点火
为什么发动机能驱动汽车？
How does an engine drive a car?
燃料爆炸推动活塞,经曲轴转为旋转动力,再驱动车轮。
Fuel explosions push pistons, turning a shaft to drive wheels.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Heywood，《内燃机基础》
Heywood, 'Internal Combustion Engine Fundamentals'
独立核验依据 · Independent verification: 核验依据 1 ISBN 9781260116106 (2018)
#活塞 #曲轴 #动力
阿特金森循环相比传统奥托循环热效率更高，但现代量产车上的“阿特金森发动机”实际是米勒循环——两者区别在哪？为何混合动力车几乎都用这类循环而传统燃油车很少用？
The Atkinson cycle offers higher thermal efficiency than the conventional Otto cycle, yet modern production 'Atkinson engines' are actually Miller-cycle engines — what distinguishes them, and why do hybrid vehicles almost universally use such cycles while conventional ICE cars rarely do?
理论阿特金森循环的膨胀行程长于压缩行程，需要复杂的连杆机构实现；米勒循环用进气门晚关（或早关）实现同样的有效膨胀比大于压缩比效果，机械上就是普通四冲程机加可变气门正时（米勒循环还常带增压中冷）。代价是进气量减少、升功率明显下降。混动车有电机补足低速与急加速扭矩，发动机可以专心运行在高效区，因此广泛采用该循环；纯燃油车若采用同样方案会感到动力不足，难以被市场接受。
In the ideal Atkinson cycle the expansion stroke exceeds the compression stroke, historically requiring intricate linkage mechanisms; the Miller cycle achieves the same effective-expansion-ratio-greater-than-compression-ratio effect by late (or early) intake-valve closing, i.e., a conventional four-stroke engine with variable valve timing, often plus turbocharging and intercooling. The penalty is reduced trapped air and markedly lower specific output. Hybrids use electric motors to supply low-speed and launch torque, letting the engine dwell in its high-efficiency island, so they adopt this cycle widely; a conventional car would feel underpowered and uncompetitive if it did the same.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Heywood,《Internal Combustion Engine Fundamentals》第2版(McGraw-Hill) 第2章;SAE论文 2012-01-1017（丰田THS-II紧凑型车动力总成）
J.B. Heywood, Internal Combustion Engine Fundamentals, 2nd ed. (McGraw-Hill), Ch.2; SAE Paper 2012-01-1017 (Development of the New THS-II Powertrain for Compact Vehicles)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9781260116106 (2018)
#内燃机与热机 #阿特金森/米勒循环与混动应用