Abstract: The X-axis dimension from the front wheel center to the driver's tread point, also known as L113 dimension, is the core dimension of the entire vehicle and the foundation of its construction. Its influencing factors involve a wide range, and it needs to be reasonably defined in the conceptual design stage. L113 is generally set as a fixed feature within the same platform. The unification of L113 can achieve standardization of the layout of the front and rear modules of the front bumper, reduce module boundary design variables. The physical boundaries involved in L113 include the layout of the front cabin, the definition of the front bumper position, the definition of the three pedal position, tire selection and envelope, and the boundary of the vehicle structure. The performance involved includes overall vehicle safety performance, human-machine comfort, and ease of entry and exit. This article investigates the influence of physical boundaries and performance requirements on L113, and explores the X-direction distance definition method from the front wheel center to the driver's tread point through the decomposition of three key main cross-sections and dimension chains, for reference.

Key words: L113 dimension; influencing factors; main section; definition methods

摘要： 前轮心到驾驶员踏点的 X 向尺寸即 L113 尺寸，是整车核心尺寸之一，其影响因素涉及 范围广，在概念设计阶段就需进行合理性定义。L113 的统一可实现前围板前后模块布局标准 化，减少模块边界设计变量。为探究 L113 尺寸的定义方法，文章主要通过将 L113 尺寸的影 响因素，包括前舱布置、前围板位置定义、三踏板位置定义、轮胎选型及包络、车身结构边 界、整车安全性能、人机舒适性、进出方便性等，分解至三个关键主断面中，并通过尺寸链 分解设计方法，得出 L113 尺寸的量化方法，以供参考。

关键词: L113 尺寸；影响因素；主断面；定义方法