Membrane type non-intrusive ice detector
First Claim
1. An ice detector adapted for mounting on a wall having a curved outer surface, said ice detector comprising a disphragm member adapted to be exposed with such wall to an air stream in which ice is to be detected, said diaphragm member having a center portion, an outer edge support portion, and a flexible wall portion extending between the outer edge support portion and the center portion, said flexible wall portion permitting deflecting movement of the center portion in direction generally normal to the diaphragm member;
- the diaphragm member being curved to form a smooth continuation of the curved outer surface of a wall on which the diaphragm member is mounted, means connected to the center portion of the diaphragm member to vibrate the center portion and having a mass that is selected to cause the natural frequency of vibration of the means to vibrate and the connected center portion of the diaphragm member to be dependent upon the flexibility of said flexible wall portion between the center portion and the outer edge support portion of said diaphragm member; and
means to sense changes in natural frequency of said means to vibrate upon change in flexibility of the flexible wall portion due to stiffness of ice accumulating on said diaphragm member.
1 Assignment
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Accused Products
Abstract
An ice detector of the vibrating element type comprises a tube that vibrates along its longitudinal axis, and is driven by an excitation coil at the natural frequency of the tube is sealed by a diaphragm which has a surface exposed to an air stream in which icing is to be sensed. The exposed diaphragm surface is deflectable during vibration of the tube at a flexible support portion of the diaphragm. As ice accumulates on the exposed surface of the flexible support the spring rate or flexibility of the flexible support changes, thereby changing the natural frequency of the vibration of the tube section. The changes in the natural frequency are sensed to determine that ice is accumulating. The diaphragm is of low mass, and small so that stiffness of small amounts of ice significantly changes the spring constant of the flexible support and the diaphragm is shaped to conform to adjacent aerodynamic surfaces.
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Citations
8 Claims
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1. An ice detector adapted for mounting on a wall having a curved outer surface, said ice detector comprising a disphragm member adapted to be exposed with such wall to an air stream in which ice is to be detected, said diaphragm member having a center portion, an outer edge support portion, and a flexible wall portion extending between the outer edge support portion and the center portion, said flexible wall portion permitting deflecting movement of the center portion in direction generally normal to the diaphragm member;
- the diaphragm member being curved to form a smooth continuation of the curved outer surface of a wall on which the diaphragm member is mounted, means connected to the center portion of the diaphragm member to vibrate the center portion and having a mass that is selected to cause the natural frequency of vibration of the means to vibrate and the connected center portion of the diaphragm member to be dependent upon the flexibility of said flexible wall portion between the center portion and the outer edge support portion of said diaphragm member; and
means to sense changes in natural frequency of said means to vibrate upon change in flexibility of the flexible wall portion due to stiffness of ice accumulating on said diaphragm member. - View Dependent Claims (2, 3)
- the diaphragm member being curved to form a smooth continuation of the curved outer surface of a wall on which the diaphragm member is mounted, means connected to the center portion of the diaphragm member to vibrate the center portion and having a mass that is selected to cause the natural frequency of vibration of the means to vibrate and the connected center portion of the diaphragm member to be dependent upon the flexibility of said flexible wall portion between the center portion and the outer edge support portion of said diaphragm member; and
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4. An ice detector comprising a small diaphragm member exposed to an air stream in which ice is to be detected, said diaphragm member having a center portion, an outer edge support portion, and a flexible wall portion extending between the outer edge support portion and the center portion, said flexible wall portion permitting deflecting movement of the center portion in direction generally normal to the diaphragm member;
- means connected to the center portion for vibrating the center portion of the diaphragm member and having a mass that is selected to cause the natural frequency of vibration of the connected center portion and the means for vibrating to be dependent upon the flexibility of said flexible wall portion between the center portion and the outer support edge portion of said diaphragm member wherein said means for vibrating said center portion comprising a tube member positioned on a side of said diaphragm member opposite from the airstream, a nodal support for supporting said tube member and dividing the tube member into first and second tube sections, the first tube section extending toward the diaphragm member and having its outer end connected to the center portion of said diaphragm member, and the second tube section extending in direction from said nodal support away from said diaphragm member, said first and second tube sections having substantially the same natural frequency of vibration in direction along the longitudinal axis, means for exciting the first and second tube sections into vibration at a natural frequency and for detecting such frequency of vibration, whereby changes in the natural frequency of one of the first and second tube sections results in an indication of change of frequency in the other tube section; and
means to sense changes in natural frequency of said means to vibrate upon change in flexibility of the flexible wall portion due to stiffness of ice accumulating on said diaphragm member. - View Dependent Claims (5, 6, 7)
- means connected to the center portion for vibrating the center portion of the diaphragm member and having a mass that is selected to cause the natural frequency of vibration of the connected center portion and the means for vibrating to be dependent upon the flexibility of said flexible wall portion between the center portion and the outer support edge portion of said diaphragm member wherein said means for vibrating said center portion comprising a tube member positioned on a side of said diaphragm member opposite from the airstream, a nodal support for supporting said tube member and dividing the tube member into first and second tube sections, the first tube section extending toward the diaphragm member and having its outer end connected to the center portion of said diaphragm member, and the second tube section extending in direction from said nodal support away from said diaphragm member, said first and second tube sections having substantially the same natural frequency of vibration in direction along the longitudinal axis, means for exciting the first and second tube sections into vibration at a natural frequency and for detecting such frequency of vibration, whereby changes in the natural frequency of one of the first and second tube sections results in an indication of change of frequency in the other tube section; and
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8. An ice detector for mounting with respect to a wall having an outer surface exposed to an airstream in which formation of ice is to be detected comprising a diaphragm member adapted to be mounted on the wall and having an outer surface in the airstream, said diaphragm member having a center portion, an outer edge support portion, and a spring wall portion extending between the outer edge support portion and the center portion, said spring wall portion permitting deflecting movement of the center portion under spring load in a first direction axis;
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a housing adapted to be mounted with respect to the wall and positioned on a side of said diaphragm member opposite from the airstream; a tube member; a support mounting said tube member to the housing to form a nodal support for the tube member and dividing the tube member into two vibrating tube sections, one of said tube sections extending from the nodal support toward the diaphragm member and having the outer end connected to the center portion of said diaphragm member for causing deflecting movement of the center portion along the first direction axis, said first direction axis being generally parallel to the orientation of the longitudinal axis of the tube member, and the other of said tube sections extending in direction from said nodal support away from said diaphragm member, said two tube sections having substantially the same natural frequency of vibration in direction along the longitudinal axis; means for exciting the tube sections into vibration along the longitudinal axis at a natural frequency, and for detecting such frequency of vibration, whereby changes in the natural frequency of one of the tube sections results in an indication of change of frequency in the other tube section; the center portion of said diaphragm vibrating with the first tube section, said first tube section and center portion being of a combined mass that is selected to cause the natural frequency of vibration of the first tube section to be dependent upon the spring constant of said spring wall portion between the center portion and the outer support portions of said diaphragm member; and means to sense changes in natural frequency of said tube sections upon change in spring constant of the spring wall portion due to stiffness of ice accumulating on the outer surface of said diaphragm member.
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Specification