Control means and automatic roll-type filter

• US 3,985,528 A
• Filed: 01/24/1975
• Issued: 10/12/1976
• Est. Priority Date: 07/05/1973
• Status: Expired due to Term

• Current Assignee: Snydergeneral Corp (Daikin Industries Ltd)
• Original Assignee: American Air Filter Co., Inc. (Daikin Industries Ltd)
• Inventors: Revell, Alan E.
• Primary Examiner(s): Nozick, Bernard
• Application Number:
  US05/543,941
• Time in Patent Office: 627 Days
• Field of Search: 55/352, 55/274, 55/DIG. 34
• US Class Current: 55/352
• CPC Class Codes: B01D 46/18 Particle separators, e.g. dust precipitators, using filtering belts
• CPC Class Codes: B01D 46/20 the belts combined with drums
• CPC Class Codes: B01D 46/46 automatic

Abstract

A control circuit for an automatic roll-type air filter including a photocell for detecting the dust load condition of the filter media and for energizing the circuit to cause the filter media to advance in response to the dust loading, a variable resistor to provide adjustment of the set-point at which the circuit is energized, and a fixed value resistor in series with the variable resistor to prevent setting of the variable resistor to a value which would allow the circuit to be energized thereby advancing the filter media when cleaned media is present in the air filter zone of the automatic roll-type air filter.

Claims

1. An air filtering apparatus comprising:

a filter media supply roll to receive a roll of filter media;

a filter media take-up roll to receive filter media from said supply roll;

an air filtering zone disposed between said supply roll and said take-up roll;

filter media extending from said media supply roll through said air filtering zone to said filter media take-up roll, so air can be treated passes through said filter media in said air filter zone; and

an adjustable, fail-safe air filter media advanced control system responsive to a reduction in the light transmitting quality of said media, said filter media advanced control system comprising;

an electric light source of controlled intensity disposed on one side of said filter media and electrically connected to a source of electrical energy, and a photocell disposed on the opposite side of said filter media from said light source and connected to a source of electrical energy;

an electric motor drivingly connected to said take-up roll to effect the advance of said media;

an energizing circuit to energize said motor to drive said take-up roll, said energizing circuit including normally open first switch means, normally open second switch means, and normally open third switch means, said first, second and third switch means and said motor being electrically connected in series to a source of electrical energy, and said second switch means being also connected in electrical series to said light source;

a warning light electrically connected to a source of electrical energy;

fourth switch means electrically connected in series with said warning light to the source of electrical energy;

fifth switch means electrically connected to said warning light and parallel to said fourth switch means;

a rheostat electrically connected in series with said photocell and in parallel to said first switch means, said rheostat enables a resistance value to be preselected which when exceeded by the resistance of said photocell initiates activation of said first switch means to energize said motor to drive said take-up roll;

a resistor electrically connected in series with said rheostat and said photocell, said resistor being of sufficient value to prevent said rheostat from being adjusted to such a low resistance value that said first switch means is activated to advance said media when clean media is present in said air filtering zone;

first relay means electrically connected to said first switch means for activating said first switch means, said first relay means being electrically connected to said photocell and parallel with said rheostat and said resistor to close said first switch means when the resistance of said photocell exceeds the resistance of said rheostat due to the quantity of light received by said photocell falling below a first predetermined value;

second relay means electrically connected to said second and fifth switch means for activating said second and fifth switch means, said second relay means being electrically connected in series with said light source to close said second switch means and open said fifth switch means when said light source is energized; and

,

third relay means electrically connected to said third and fourth switch means, said third relay means being electrically connected to said photocell in series with said rheostat and said resistor and in parallel with said first relay means, said third relay means has less resistance than said first relay means, said third relay means to close said third switch means and open said fourth switch means when the resistance of said photocell exceeds the resistance of said third switch means and is less than the resistance of said rheostat and said resistor due to the quantity of light received by said photocell falling below a second predetermined value, said second predetermined value being higher than said first predetermined value,

whereby said motor is energized when said first, second and third switch means are each in a closed position, said warning light is energized and said motor de-energized when said fifth switch means is closed and said second switch means is open indicating the light source is de-energized, and said warning light is energized and said motor de-energized when said fourth switch means is closed and said third switch means is open indicating that the filter media has been exhausted from said air filtering zone.

2. The apparatus of claim 1, wherein said rheostat has a maximum resistance value on the order of ten times the resistance value of said fixed resistor.

3. The apparatus of claim 1, wherein:

the maximum resistance value of said rheostat is on the order of 25 ohms; and

the resistance value of said fixed resistor is on the order of 2.7 ohms.