| # | Country | Total Patents | |
|---|---|---|---|
| #1 | United States | 9 | |
| #2 | Canada | 3 | |
| #3 | Germany | 2 | |
| #4 | United Kingdom | 2 | |
| #5 | France | 1 |
| # | Industry | |
|---|---|---|
| #1 | Engines, pumps and turbines | |
| #2 | Electrical machinery and energy | |
| #3 | Environmental technology |
| # | Name | Total Patents |
|---|---|---|
| #1 | Harper Jr William | 9 |
| #2 | Harper William Jr | 3 |
| Publication | Filing date | Title |
|---|---|---|
| GB545351A | Improvements in or relating to spark plugs | |
| US2205196A | Spark plug | |
| US2127513A | Spark plug | |
| US2127512A | Spark plug | |
| US2135939A | Differential pressure mechanism | |
| US2153501A | Piston for internal combustion engines | |
| DE634053C | Ignition device for internal combustion engines | |
| US2025203A | Combustion engine | |
| US2041709A | Combustion engine | |
| US2025202A | Combustion engine | |
| US2041708A | Combustion engine | |
| CA392922A | Spark plug | |
| CA394425A | Spark plug | |
| CA360806A | Internal combustion engine |