An Empirical Investigation Into Co-Patent Networks and Their Characteristics, Evolution: The Case of China’s Rail Transit Equipment Industry

Faced with fierce external competition and rapidly growing demand, China’s rail transit equipment industry can advance by strengthening the collaborative performance among industries, universities, and research institutes (I-U-R). This study aims to construct and visualize the I-U-R co-patent networks of China’s rail transit equipment industry to gain a comprehensive understanding of the patterns and dynamics of collaborative innovation. Based on 2876 cooperative patents from the China National Knowledge Infrastructure database (1986–2018), the study applies statistical and social network analysis methods to systematically analyze the full evolutionary trajectory of I-U-R co-patent networks in China’s rail transit equipment industry, from “quantitative change” (scale expansion) to “qualitative change” (structural transformation). The results show that the connections among network innovation participants have become progressively closer, the network has expanded in scale, and distinct developmental stages have emerged. The network structure has evolved from a single-core to a cross-regional, multi-core configuration, with enterprises consolidating their dominant position, occupying the core of the network. This study provides theoretical support for strengthening China’s rail transit equipment industry’s co-patent networks and contributes to both collaborative innovation network theory and co-patent research methodology.