Surging investment by Chinese companies in U.S. research labs is yielding a fast-growing trove of patents, part of a push to mine the U.S. for ideas to help China shift from being the world’s factory floor to a driver of innovation, according to an analysis of Thomson Reuters’ global intellectual property database. Patented inventions by Chinese firms that involved at least one U.S. researcher roughly doubled worldwide in each of the last three years, reaching 910 in 2014.