# US 2021/0330018 A1 · Protective helmet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0330018 A1 - Document ID: US20210330018A1 - Status: Published application - Kind: A1 - Application number: 17/218,666 - Filed: 2021-03-31 - Published: 2021-10-28 - Earliest claimed: 2020-04-27 - Assignees: Honeywell International Inc. - Applicants: Honeywell International Inc. - Inventors: Prudhvi Krishna YARLAGADDA; Rizwan AHMAD; Alan SCHIERENBECK - Web page: https://patentgrep.com/patent/US20210330018A1 ## CPC - A42B 3/064: {with relative movement between layers} - A42B 3/065: {Corrugated or ribbed shells} - A42B 3/124: {with at least one corrugated or ribbed layer} - A42B 3/14: Suspension devices - A42B: HATS; HEAD COVERINGS (headbands A41D20/00; head-scarves A41D23/00) ## Abstract Various embodiments are directed to a protective helmet comprising: a protective shell having a substantially dome-shaped configuration, the protective shell comprising: an outer shell surface; an inner shell surface; and at least one groove extending along at least a portion of the inner shell surface, wherein the at least one groove is embodied as a material recess within a wall thickness; wherein a ratio of the shell thickness at a first shell location adjacent the at least one groove to the groove depth of the at least one groove is at least a predetermined threshold value. In various embodiments, a protective helmet may further comprise an impact cap and/or an inner ring, one or both of which may comprise a respective groove configuration. In various embodiments, the one or more groove configurations may be configured to reduce the helmet weight of the invention by at least 15%. ## Claims ### Claim 1 A protective helmet comprising: a protective shell having a substantially dome-shaped configuration, the protective shell comprising: an outer shell surface; an inner shell surface comprising a lower perimeter and defining, at least in part, an internal shell portion configured to receive at least a portion of a head of a user extending through the lower perimeter of the inner shell surface; and at least one groove extending along at least a portion of the inner shell surface, wherein the at least one groove is defined at least in part by a groove depth; wherein the protective shell is defined at least in part by a shell thickness defined at least in part by a perpendicular distance between the outer shell surface and the inner shell surface; wherein the at least one groove is embodied as a material recess within the cap thickness extending from the inner shell surface to a maximum recession point, wherein the groove depth of the at least one groove is defined at least in part by a distance between the inner shell surface and the maximum recession point of the at least one groove; and wherein a ratio of the shell thickness at a first shell location adjacent the at least one groove to the groove depth of the at least one groove is at least a predetermined threshold value. ### Claim 2 (depends on 1) The protective helmet of claim 1, wherein the predetermined threshold value of the ratio of the shell thickness at the first shell location adjacent the at least one groove to the groove depth of the at least one groove is between 1.5:1 and 3:1. ### Claim 3 (depends on 1) The protective helmet of claim 1, wherein the groove configuration is configured to reduce a shell weight of the protective shell by at least 10%. ### Claim 4 (depends on 1) The protective helmet of claim 1, wherein the ratio of the shell thickness at the first shell location adjacent the at least one groove to the groove depth of the at least one groove is different than a second ratio of the shell thickness at a second shell location adjacent the at least one groove to the groove depth of the at least one groove. ### Claim 5 A protective helmet comprising: a protective shell; and an inner ring; wherein each of the protective shell and the inner ring are defined by a respective wall thickness; wherein one or more of the protective shell and the inner ring comprises a groove configuration defined by at least one groove, wherein the at least one groove is embodied as a material recess extending into the respective wall thickness from a respective surface thereof; and wherein the groove configuration is configured to reduce an amount of material within the protective helmet. ### Claim 6 (depends on 5) The protective helmet of claim 5, wherein the at least one groove is defined in part by a respective groove depth, and wherein the groove configuration is defined by a ratio of the respective wall thickness at a first location adjacent the at least one groove to the groove depth of the at least one groove is at least a predetermined threshold value. ### Claim 7 (depends on 6) The protective helmet of claim 6, wherein the predetermined threshold value of the ratio of the respective wall thickness at the first location adjacent the at least one groove to the groove depth of the at least one groove is between 1.5:1 and 3:1. ### Claim 8 (depends on 5) The protective helmet of claim 5, wherein each of the protective shell and the inner ring comprises a respective groove configuration. ### Claim 9 (depends on 5) The protective helmet of claim 5, wherein the groove configuration is configured to reduce a helmet weight of the protective helmet by at least 15%. ### Claim 10 (depends on 5) The protective helmet of claim 5, wherein the ratio of the respective wall thickness at the first location adjacent the at least one groove to the groove depth of the at least one groove is different than a second ratio of the respective wall thickness at a second location adjacent the at least one groove to the groove depth of the at least one groove. ### Claim 11 (depends on 5) The protective helmet of claim 5, further comprising an impact cap, wherein the protective helmet is configured such that the impact cap is positioned at least partially between the protective shell and the inner ring such that the impact cap defines an intermediate buffer between the shell and the inner ring. ### Claim 12 (depends on 9) The protective helmet of claim 9, wherein the impact cap comprises at least one impact cap groove configuration defined by one or more impact cap grooves, wherein the one or more impact cap groove are embodied as a material recess extending into an impact cap wall thickness from an external surface thereof. ### Claim 13 A protective helmet comprising: a protective shell; an impact cap; and an inner ring; wherein each of the protective shell, the impact cap, and the inner ring are defined by a respective wall thickness; wherein one or more of the protective shell, the impact cap, and the inner ring comprises a groove configuration defined by one or more grooves, wherein the one or more grooves are embodied as a material recess extending into the respective wall thickness from a respective surface thereof; and wherein the groove configuration is configured to reduce an amount of material within the protective helmet. ### Claim 14 (depends on 13) The protective helmet of claim 13, wherein the at least one groove is defined in part by a respective groove depth, and wherein the groove configuration is defined by a ratio of the respective wall thickness at a first location adjacent the at least one groove to the groove depth of the at least one groove is at least a predetermined threshold value. ### Claim 15 (depends on 14) The protective helmet of claim 14, wherein the predetermined threshold value of the ratio of the respective wall thickness at the first location adjacent the at least one groove to the groove depth of the at least one groove is between 1.5:1 and 3:1. ### Claim 16 (depends on 13) The protective helmet of claim 13, wherein each of the protective shell, the impact cap, and the inner ring comprises a respective groove configuration. ### Claim 17 (depends on 13) The protective helmet of claim 13, wherein the groove configuration is configured to reduce a helmet weight of the protective helmet by at least 15%. ### Claim 18 (depends on 13) The protective helmet of claim 13, wherein the ratio of the respective wall thickness at the first location adjacent the at least one groove to the groove depth of the at least one groove is different than a second ratio of the respective wall thickness at a second location adjacent the at least one groove to the groove depth of the at least one groove.