This case involves claim construction in the patent administrative litigation. The patentee claims that the "retaining insert" in claim 1 should be interpreted as the insertion of the water guiding cross pipe and the insert base body described in the embodiment of the specification and the accompanying drawings. In the judgment of the second instance, the Beijing Higher People's Court held that: First, the specific meaning of the retaining insert should be defined in accordance with the specific language of the claim 1, and the written record of claim 1 has been able to clearly confirm the structure and the function of the retaining insert, therefore the scope of the protection of claim 1 cannot be further reduced according to the description. Second, according to the description of the present invention, the solution of the technical problem of improving the measurement sensitivity of the turbine flow meter according to the present invention is not related to whether the water conducting cross pipe holding the insert and the insert base are connected to each other or not. In addition, the function of inserting the cross tube between the cross pipe and the insert base body is for positioning, not for improving the measurement sensitivity. Therefore, from the viewpoint of the invention, the technical problem to be solved and the technical effects expected, both cannot be interpreted as a water-conducting cross pipe and an insert base body being plugged with each other; thirdly, according to the principle of difference explanation of a claim, the specific limitations in the specification regarding the mutual connection of the water-carrying cross pipe and the insert base body are set forth in the dependent claim 18, rather than in claim 1. Based on the above major points of view, the second instance of Beijing Higher People's Court decides to revoke the judgment of first instance of Beijing No. 1 Intermediate People's Court and upholds the decision of the Patent Reexamination Board of SIPO to declare all the patents involved invalid.