- All sections
- E - Fixed constructions
- E21D - Shaftstunnelsgallerieslarge underground chambers
- E21D 11/20 - Special cross-sections, e.g. corrugated
Patent holdings for IPC class E21D 11/20
Total number of patents in this class: 10
10-year publication summary
|
0
|
2
|
0
|
0
|
0
|
1
|
1
|
2
|
0
|
0
|
| 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
Principal owners for this class
| Owner |
All patents
|
This class
|
|---|---|---|
| AIL International Inc. | 66 |
2 |
| China University of Mining and Technology | 1256 |
1 |
| Nippon Steel & Sumikin Metal Products Co., Ltd. | 34 |
1 |
| Shonan Gosei-Jushi Seisakusho K.K. | 38 |
1 |
| Cheong AM | 2 |
1 |
| Pyungsan SI Ltd. | 4 |
1 |
| China Railway Tunnel Group Co., Ltd | 24 |
1 |
| State Key Laboratory of Shield Machine and Boring Technology | 16 |
1 |
| FCI Holdings Delaware, LLC | 86 |
1 |
| Other owners | 0 |