Frost detector

Claim 2

A frost detector for a refrigeration device having an evaporating coil, comprising: a housing, said housing having a light impervious passageway through it, said housing including at least one side wall partially defining said passageway, said side wall having an opening in it; a thermal conductive means mounted in said opening, said conducting means having a first surface area closing the opening in said passageway, and a second surface area; an energy source operatively mounted to said housing, said energy source being adapted to illuminate the first surface area of said thermal conducting means; an energy sensitive device operatively mounted to said housing to sense the level of energy reflected from said thermal conductive means; means for mounting said housing to a refrigerant carrying portion of said refrigeration device along the second surface of said thermal conducting means, the thermal resistance between the second surface of said thermal conducting means and the refrigerant carrying portion of said refrigeration device being adjustable to vary the heat transfer characteristic of said thermal conducting means; and means for operatively connecting said light impervious passageway to a source of air, said connecting means being positioned so that the air pressure drop across said evaporating coil forces air through said light impervious passageway.

Claim 3

The detector of claim 1 further characterized by means for varying the thermal resistance between the second surface of said thermal conducting means and the refrigerant carrying portion of said refrigeration device, said thermal resistance varying means comprising a material having a thermal resistance different from the thermal resistance of said thermal conductive means, said varying means being placed between the refrigerant carrying portion of said refrigeration device and the second surface of said thermal conductive means.

Claim 4

The detector of claim 2 wherein said evaporating coil is further characterized by a refrigerant carrying coil having an inlet, a main body portion, and an outlet, the connecting means of said frost detector being operatively connected to said refrigeration device along one of the inlet, the main body portion, and the outlet of said condensing coil.

Claim 5

The detector of claim 3 further characterized by means for adjusting air flow through said light impervious passage, said adjusting means including means for restricting the size of said light impervious passage.

Claim 6

The detector of claim 4 wherein the second surface of said thermal conducting means has a groove formed in it for engaging the refrigerant carrying portion of said refrigeration device.

Claim 7

A frost detector for a refrigeration device having a coil for circulating a refrigerant, which comprises: a housing, said housing including an enclosure having an inlet, an outlet and an air passageway between said inlet and said outlet; means for adjusting air flow through said light impervious passage by restricting the air passageway at said inlet; thermal conductive means mounted in said enclosure, said thermal conductive means having a first surface area exposed in said air passageway, and a second surface area; an energy source operatively mounted to said housing, said energy source adapted to illuminate the first surface area of said thermal conductive means; an energy sensitive device operatively mounted to said housing, said energy sensitive device adapted to sense the level of energy reflected from said thermal conductive means; means for mounting said sensor to a refrigerant carrying portion of said refrigeration device along the second surface of said thermal conductive means; and means for directing an air flow through said air passageway and along the first surface of said conductive means.

Claim 8

A frost detector for a refrigeration device having a coil for circulating a refrigerant, which comprises: a housing, said housing including an enclosure having an inlet, an outlet and an air passageway between said inlet and said outlet; means for adjusting air flow through said light impervious passage by restricting the air passageway at said inlet; thermal conductive means mounted in said enclosure, said thermal conductive means having a first surface area exposed in said air passageway, and a second surface area; an energy source operatively mounted to said housing, said energy source adapted to illuminate the first surface area of said thermal conductive means; an energy sensitive device operatively mounted to said housing, said energy sensitive device adapted to sense the level of energy reflected from said thermal conductive means; means for mounting said sensor to a refrigerant carrying portion of said refrigeration device along the second surface of said thermal conductive means; and means for directing an air flow through said air passageway and along the first surface of said conductive means.

Claim 9

The detector of claim 6 wherein said air passageway is impervious to external light.

Claim 10

The detector of claim 7 wherein said air directing means is positioned so that the air pressure drop across the coil of said refrigeration device forces air through said air passageway.

Claim 11

The detector of claim 8 further characterized by means for varying the thermal contact between the second surface of said thermal conducting means and the refrigerant carrying portion of said refrigeration device.

Claim 12

The detector of claim 9 wherein the coil of said refrigerating device has an inlet, a main body portion and an outlet, the mounting means of said detector being operatively connected to said refrigeration device along one of the inlet, the main body portion, and the outlet of said condensing coil.

Claim 13

In a refrigeration device having an evaporating coil, said coil having a refrigerant carrying part including an inlet, an outlet and a main body portion, the improvement which comprises detector means for initiating a defrost cycle by sensing frost formation and for terminating the defrost cycle upon removal of frost, said detector means comprising a housing, said housing including an enclosure having an inlet, an outlet, and an air passageway between said inlet and said outlet, thermal conductive means having a first surface area exposed in said air passageway and a second surface area, a light source operatively mounted to said housing, said light source adapted to illuminate said first surface area, a light sensitive device operatively mounted to said housing, said light sensitive device being adapted to sense the level of light reflected from said thermal conductive means, means for mounting said sensor to a refrigerant carrying portion of said refrigeration device along the second surface of said thermal conductive means, means for directing an air flow through the air passageway of said housing, means responsive to said light sensitive device for initiating a defrost cycle upon the formation of a predetermined amount of frost on the first surface area of said thermal conductive means, and for terminating the defrost cycle upon removal of a predetermined amount of frost from the first surface area of said thermal conductive means, and means for adjusting the frosting conditions of said thermal conductive means independently of said refrigeration device.

Claim 14

In a refrigeration device having an evaporating coil, said coil having a refrigerant carrying part including an inlet, an outlet and a main body portion, the improvement which comprises detector means for initiating a defrost cycle by sensing frost formation and for terminating the defrost cycle upon removal of frost, said detector means comprising a housing, said housing including an enclosure having an inlet, an outlet, and an air passageway between said inlet and said outlet, thermal conductive means having a first surface area exposed in said air passageway and a second surface area, a light source operatively mounted to said housing, said light source adapted to illuminate said first surface area, a light sensitive device operatively mounted to said housing, said light sensitive device being adapted to sense the level of light reflected from said thermal conductive means, means for mounting said sensor to a refrigerant carrying portion of said refrigeration device along the second surface of said thermal conductive means, means for directing an air flow through the air passageway of said housing, means responsive to said light sensitive device for initiating a defrost cycle upon the formation of a predetermined amount of frost on the first surface area of said thermal conductive means, and for terminating the defrost cycle upon removal of a predetermined amount of frost from the first surface area of said thermal conductive means, and means for adjusting the frosting conditions of said thermal conductive means independently of said refrigeration device.

Claim 15

The improvement of claim 11 wherein said adjusting means comprises means for varying thermal contact between the second surface of said thermal conducting means and the refrigerant carrying portion of said refrigeration device; and means for adjusting air flow through said light impervious passageway.

Claim 16

The improvement of claim 12 wherein said air flow adjusting means comprises means for altering the size of the inlet of said enclosure.

Claim 17

The improvement of claim 13 wherein the means for varying thermal contact comprises a material placed between the refrigerant carrying portion of said refrigeration device and a second surface of said thermal conductive means, said material having a thermal resistance different from the thermal resistance of said thermal conductive means.