lower dead center

简明释义

下死点

英英释义

例句

1.The engine's compression stroke begins after the piston moves up from the lower dead center.

活塞从下止点向上移动后，发动机的压缩行程开始。

2.To ensure proper engine timing, you must check the position of the crankshaft at lower dead center.

为了确保发动机的正确时序，您必须检查曲轴在下止点的位置。

3.The piston reaches the lower dead center when it is at its lowest position in the cylinder.

活塞在气缸的最低位置时到达下止点。

4.During the cycle, the crankshaft rotates and brings the piston to the lower dead center before moving up again.

在循环过程中，曲轴旋转并将活塞带到下止点，然后再次向上移动。

5.When tuning the engine, you should always mark the lower dead center for reference.

在调整发动机时，您应该始终标记下止点作为参考。

作文

The concept of lower dead center is crucial in the field of mechanics, particularly when discussing the operation of engines. To fully comprehend what this term means, it is essential to understand its role within the context of a reciprocating engine. In such engines, the pistons move up and down within the cylinders, converting fuel energy into mechanical energy. The positions of these pistons are vital for the efficient functioning of the engine, and one of the key positions is the lower dead center (LDC).

When we refer to the lower dead center, we are describing the lowest point that a piston reaches during its cycle. At this point, the piston has completed its downward stroke and is at the extreme bottom of its travel. This position is critical because it marks the moment when the combustion chamber is at its maximum volume, allowing for the intake of air and fuel mixture for the next cycle. Understanding the timing and mechanics at this point can significantly affect an engine's performance.

In practical terms, the lower dead center is where the engine prepares for the next power stroke. Once the piston reaches this point, it will begin to move back up, compressing the air-fuel mixture to prepare for ignition. If the timing is not correct, or if the engine is not designed properly, it can lead to inefficient fuel combustion, reduced power output, and increased emissions. Therefore, engineers pay close attention to the design of the crankshaft and connecting rods to ensure that the transition through the lower dead center is smooth and efficient.

Moreover, the lower dead center also plays a significant role in the overall design of the engine. It affects the engine's displacement, which is crucial for determining the power output and efficiency. A larger displacement generally means more power, but it also requires careful consideration of how the engine will perform at various RPMs (revolutions per minute). The relationship between the lower dead center and the upper dead center (the highest point of the piston) is fundamental in calculating the engine’s compression ratio, which directly influences its performance characteristics.

In conclusion, understanding the lower dead center is essential for anyone involved in engine design and maintenance. It is not just a technical term; it embodies the intricate balance of engineering that allows modern vehicles to operate efficiently. By grasping the significance of this position within the engine cycle, we can appreciate the complexities of automotive technology and the importance of precision in engineering. As we continue to innovate and improve engine designs, the principles surrounding the lower dead center will remain a foundational aspect of mechanical engineering education and practice.

在机械领域，特别是在讨论发动机运作时，下止点的概念至关重要。要充分理解这个术语的含义，有必要在往复发动机的背景下理解它的作用。在这样的发动机中，活塞在气缸内上下移动，将燃料能量转化为机械能。这些活塞的位置对于发动机的高效运行至关重要，而其中一个关键位置就是下止点（LDC）。

当我们提到下止点时，我们描述的是活塞在其循环中达到的最低点。在这一点上，活塞完成了向下的行程，并处于其运动的最底部。这个位置至关重要，因为它标志着燃烧室达到最大体积的时刻，允许在下一个循环中吸入空气和燃料混合物。理解这个时刻的时机和机制可以显著影响发动机的性能。

在实际操作中，下止点是发动机为下一个动力冲程做准备的地方。一旦活塞达到这一点，它就会开始向上移动，压缩空气-燃料混合物以准备点火。如果时机不正确，或者发动机设计不当，可能会导致燃料燃烧效率低下、功率输出减少和排放增加。因此，工程师们非常关注曲轴和连杆的设计，以确保活塞通过下止点的过渡平稳且高效。

此外，下止点在发动机的整体设计中也扮演着重要角色。它影响发动机的排量，这对确定功率输出和效率至关重要。更大的排量通常意味着更多的功率，但这也需要仔细考虑发动机在不同转速下的表现。下止点与上止点（活塞的最高点）之间的关系在计算发动机的压缩比时是基础，这直接影响其性能特征。

总之，理解下止点对于任何参与发动机设计和维护的人来说都是必不可少的。它不仅仅是一个技术术语；它体现了现代车辆高效运作所需的工程精密平衡。通过掌握这一位置在发动机循环中的重要性，我们可以欣赏汽车技术的复杂性以及工程精确性的重要性。随着我们继续创新和改进发动机设计，围绕下止点的原则将始终是机械工程教育和实践的基础方面。