Abstract: The inference and solution process of air-conditioning system fault diagnosis is analysed in accordance with the operating property of air-conditioning system. A fuzzy description method and a fuzzy inference method of expert system based on diagnosis knowledge are proposed. The method of calculating the confidence of fuzzy affirm is elaborated with positive reasoning, negative reasoning and mixed positive-negative reasoning in fault diagnosis inference, and the application examples are given.

Key words: Air-conditioning system; Fault diagnosis; Fuzzy description; Fuzzy inference; Fuzzy affirm; Confidence

摘要： 针对空调系统的故障诊断问题及其特点，提出了一种基于诊断知识的模糊描述和模糊推理方法，阐述了空调系统故障诊断专家系统中前向推理、后向推理以及正反向混合推理模糊断言可信度的计算方法，并且给出了相应的实例。

关键词: 空调系统；故障诊断；模糊描述；模糊推理；模糊断言；可信度