Maryland's Defense Patent Database

The defense community in Maryland is an R&D powerhouse. Use this database to see the innovative patents that are poised for commercialization.

Data is provided by DoD Naval labs in Southern Maryland. Database funding supported by the DoD Office of Economic Adjustment through a Defense Industry Adjustment grant program.

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Air-safed underwater fuze system for launched munitions

Patent Number: 6,131,516

AbstractAn air-safed underwater fuze system is provided for munitions that are to launch-deployed and water-detonated. A housing defines a first bore contiguous with a second bore. Radial ports in the housing communicate with the first bore. A first piston is slidably mounted in the first bore and a second piston is slidably mounted in the second bore and positioned flush with the first bore. Piston control means are coupled between the munitions and first piston for positioning the first piston in a first position prior to launch in which the first piston seals off the radial ports while being spaced apart from the second piston to define a chamber. The piston control means moves the first piston at launch to a second position so that the chamber expands and the radial ports are in communication with the chamber. The piston control means further drives the first piston from its second position towards its first position at a specified time after launch. Once the first piston seals off the radial ports, the first piston pressurizes the water in the chamber. As a result, the second piston is driven along the second bore as actuating movement. A firing mechanism is provided in communication with the second bore and coupled to the munitions. The firing mechanism is responsive to the actuating movement of the second piston to generate detonation energy for the munitions.
Patent Number6,131,516 Issue Date2000-10-17 Link USPTO website

Primary Category

Biographical Information


  • Matthew J. Sanford, Bel Alton, MD
  • Keith B. Lewis, King George, VA


  • The United States of America as represented by the Secretary of the Navy

Executive Summary

This patent was granted in 1 year, 314 days, which is a faster than average speed.

It has 20 claims, which is fewer than average for this category.

Its proximity to basic research is much less than others in this category, and it displays a slower than average technology cycle time.

This patent received far fewer citations from other patents, and references far fewer other patents, as compared to other patents in this category.

Grant Time

1 year, 314 days



Patent Grant Time

This patent had a faster than average grant time compared to others in this category.

Patent grant time can be influenced by many factors. Activities within the USPTO that are beyond the control of patent attornies can influence grant time, but short grant times can also indicate well-written patents and dedicated efforts to respond rapidly to USPTO office actions with strong arguments. Shorter grant times are preferable, and the scores for this section are inverse measures — higher scores are better.

Patent Claims

This patent has fewer claims compared to others in this category.

The number of claims in a patent is correlated with its strength. Because greater claim counts increase the cost of a patent, more claims can indicate the importance an applicant assigns to a patent. Importantly, some may elect to file claims across multiple patents. A higher score in this metric indicates more claims, relative to others in this category.

Citations From Other Patents

This patent has received far fewer citations from other patents, than others in this category.

Citations from other patents are an important measure of the significance of a patent. More citations indicate that other technologies build on a patent. Higher scores in this metric are better, and indicate more citations from other patents.

Citations to Other Patents

This patent referenced many more citations to other patents, than others in this category.

A lower number of citations to other patents can be a sign of diminished patent strength. More citations indicate dependence on more other technologies. Higher scores in this category are better, and indicate fewer citations to other patents.

Research and Innovation Indicators
These are percentile ranks — they indicate the percentage of peers with lower scores.

Proximity to Basic Research



This patent has much less proximity to basic research compared to others in this category.

Proximity to basic research is measured by comparing the number of citations to non-patent literature among a cohort of patents. Because most non-patent citations are primary research papers, a higher count indicates greater proximity to basic research.