Main contents of this paper are summarized as following : ( 1 ) on the basis of deeply researching the processes and characteristics of product variant design , this paper puts forward the product model and the intelligent reasoning model for variant design ; they are the hierarchical model for product variant design and hybrid reasoning model that cbr is the core . the frame of knowledge - based variant design is puts forward . the system includes four sub - systems : the product recourse base subsystem , the product recourse managing subsystem , the variant design subsystem , and the design evaluation subsystem 具体研究内容如下： （ 1 ）深入研究了产品变型设计过程和特点，提出了面向变型设计的产品模型和智能推理模型，它们分别是产品变型设计层次化模型、以cbr为核心的混合推理模型；建立了基于知识的产品变型设计系统框架，该系统包括四个子系统：产品资源库子系统、产品资源管理子系统、变型设计子系统和设计检验子系统。
In the course of designing reasoning machine , this article uses forward inference and the tactics of best - first search . and in connection with much of fuzzy knowledge , it introduces confidence theory to infer the formula of confidence which propagate in and / or tree , and illustrates how to calculate the confidence when it propagate in the course of automobile components failure analysis reasoning 在推理机的编制过程中，本文采用了正向推理方法及最好优先搜索策略，同时针对知识库中大量的模糊知识，本文引入了可信度推理模型，推导了可信度在与或树中传播计算公式，并举例说明了在汽车零部件失效分析推理过程中可信度的传播计算方法。
