Issued Patents 1997
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5617823 | Spark-ignited reciprocating piston engine having a subdivided combustion chamber | Karl H. Hellmann, Gary W. Rogers, Ulrich Hilger | 1997-04-08 |
| 5611300 | Floating piston, piston-valve engine | — | 1997-03-18 |
| 5609131 | Multi-stage combustion engine | Karl H. Hellman | 1997-03-11 |