Impact-absorbing sound-attenuating earcup

• US 5,023,955 A
• Filed: 04/13/1989
• Issued: 06/18/1991
• Est. Priority Date: 04/13/1989
• Status: Expired due to Fees

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Westgate, Charles A., Murphy, John A. II
• Primary Examiner(s): NERBUN, PETER P
• Application Number:
  US07/337,407
• Time in Patent Office: 796 Days
• Field of Search: 2/209, 2/423, 2/6, 2/411, 2/412, 181/129
• US Class Current: 2/209
• CPC Class Codes: A61F 11/14 external, e.g. earcaps or earmuffs
• CPC Class Codes: Y10S 2/909 Head protector, e.g. helmet, goggles

Abstract

A sound-attenuating impact-absorbing earcup comprises a shell having a plurality of generally circular recesses adjacent to the periphery of the cup which function as stiffening contours. The stiffening contours increase the effective stiffness of the earcup shell, improving its sound attenuating capability, and also concentrate applied stress onto those portions of the stiffening contours nearest the point of applied stress. Sufficient applied force causes the shell to fracture in the areas of the stress concentrators, thereby to absorb impact energy in a controlled manner without transmitting it to the head of the wearer. To further enhance its sound-attenuating and impact-absorbing capabilities, the earcup is formed of a low-tensile-strength, high-elongation, high-loss-factor material such as polyvinyl chloride or similar polymer.

Claims

1. A sound attenuating earcup for insulating the ear of a wearer from ambient sound while inhibiting transmission to the wearer'"'"'s head through the earcup of shocks of impact from severe bumps or the like which might otherwise injure the head of the wearer comprising a discrete hollow cup-shaped crushable shell forming a cavity for the wearer'"'"'s ear to provide a sound-attenuating chamber around the ear, said shell having a periphery toward which stress resulting from a shock of impact travels along a path from a point of impact adjacent to the center of the shell, said shell being formed with stress concentrators, each of which has an appreciable extent in a direction across said path from said point of impact toward said periphery, said shell being formed of such a material and of such a thickness as to maintain its rigidity in ordinary use and to collapse upon impact from such severe bumps or the like to dissipate energy at an applied force less than that required to crush the skull of the wearer, said stress concentrators forming recesses in said shell, the surface of said shell having a center point, said recesses having edge portions extending generally tangentially relative to a line perpendicular to said path of stress resulting from a force applied at said point.

2. An earcup as in claim 1 in which said recesses are generally circular.

3. An earcup as in claim 1 in which said generally tangentially extending edge portions extend along a substantial portion of a closed curve surrounding said point.

4. An earcup as in claim 3 in which said generally tangentially extending edge portions comprise at least about 45% of the length of said curve.

5. An earcup as in claim 1 in which the ratio of the lengths of said portions to the area of said recesses is at least about 0.12 inch per square inch.

6. A sound-attenuating earcup as in claim 1 in which said shell is formed of a material having a tensile strength of not more than about 3,000 pounds per square inch, an ultimate elongation of not less than about twenty percent and a loss factor at least 0.10 at 68°

F. and upon subjecting the earcup to sound energy at a frequency of 1,000 Hz and being of such a thickness as to maintain its rigidity in ordinary use and to collapse upon impact from such severe bumps or the like to dissipate energy at an applied force less than that required to crush the skull of the wearer.