Board mounted sensor placement into a furnace duct

• US 6,254,008 B1
• Filed: 05/14/1999
• Issued: 07/03/2001
• Est. Priority Date: 05/14/1999
• Status: Active Grant

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Erickson, James E., Tinucci, Thomas C.
• Primary Examiner(s): WAYNER, WILLIAM E
• Application Number:
  US09/312,408
• Time in Patent Office: 781 Days
• Field of Search: 236/DIG.19, 236/44.R, 236/44.A, 126/113, 734/31, 73/290.2, 374/147
• US Class Current: 236/44.00A
• CPC Class Codes: G01N 33/0009 General constructional details of gas analysers, e.g. portable test equipment G01N1/22 takes precedence
• CPC Class Codes: G05D 22/02 characterised by the use of electric means

Abstract

A method and apparatus for protecting humidity sensing equipment within an enclosure that can be mounted in the return airflow of a furnace duct. The humidity sensing equipment is mounted on a printed wiring board, which is protected between a mounting base and an operational cover. The mounting base includes a protective shield which allows the humidity sensing equipment to protrude into the furnace duct and prevents damage to the humidity sensing equipment during installation.

Claims

1. A method for mounting a humidity sensor in a furnace duct, comprising:

a.) forming a base having an opening extending therethrough, said opening protected on one side by a protective shield;

b.) separating a wiring board into first and second pieces, the first piece of said wiring board having a sensing element thereon and the second piece of said wiring board have associated controls thereon;

c.) connecting the first and second pieces of said wiring board by means of a flexible jumper;

d.) bending the flexible jumper so as to cause the first piece of said wiring board to lie essentially parallel to the second piece of said wiring board;

e.) disposing said sensing element though the opening into the protective shield on said base; and

f.) securing said base to the furnace duct so that the sensing element is placed into airflow within the furnace duct.

2. The method for mounting a humidity sensor of claim 1 further comprising the step of:

e₂.) creating an opening in the furnace duct, the opening being large enough to permit passage of the protective shield therethrough.

3. The method for mounting a humidity sensor of claim 1 further comprising the steps of:

h.) placing a first cover over said first and second wiring boards; and

i.) fastening said first cover to said base.

4. The method for mounting a humidity sensor of claim 3 further comprising the steps of:

j.) placing a second cover over said first cover; and

k.) fastening said second cover to said first cover.

5. The method for mounting a humidity sensor of claim 1 wherein:

said sensing element is a humidity-sensing element.

6. A humidistat mounting package for a printed circuit board, the printed circuit board having a sensor attached thereto, comprising:

a longitudinally extending housing base having an opening for passthrough of the sensor, the opening covered by a generally perpendicular cylindrical frame surrounding the opening and defining a protective area surrounding the sensor;

a housing cover;

a attachment means for securing the first housing cover to the housing base; and

a second attachment means for attaching the humidistat to a vertical surface.

7. The humidistat mounting package of claim 6 wherein said sensor is a humidity sensor.

8. The humidistat mounting package of claim 6 wherein said attachment means further comprises:

at least one springable latching element secured to the housing cover;

the at least one springable latching element operable to secure the cover to the base when the cover is pressed toward the base.

9. An improved humidity control mounting package of the type in which a sensing element is mounted proximate to a flat base plate and housing cover, the housing cover having a cooperative means for joining the cover to the base plate, wherein the improvement comprises:

an opening in the base plate extending therethrough; and

a protective shield disposed about the opening in the base plate, the protective shield extending outward from the base plate and the sensing element disposed within the protective shield.

10. The improved humidity control mounting package of claim 9 wherein the base plate is mountable to a furnace duct.

11. A base member for mounting a humidity control device comprising:

a substantially flat plate having a plurality of mounting holes for securing said flat plate to a furnace plenum;

an aperture extending though said flat plate, said aperture suitable for receiving a humidity sensing assembly;

a protective shield disposed about said aperture, said protective shield extending away from the base plate and having openings for the passage of air; and

a plurality of bosses extending from said flat plate.

12. The base member of claim 11 further including:

at least one latching area, suitable for securing a springable latching element to the base plate.

13. A method for fabricating a device including a transducer for converting a sensed value of an environmental condition to an electrical variable and a board mounted circuit for processing the electrical variable, comprising the steps of:

forming a circuit board having a primary surface and including first and second sections joined by at least one flexible jumper, the first section of the circuit board being adapted to hold on its primary surface and in electrical communication with said flexible jumper, a transducer for sensing a predetermined environmental condition, the second section of the circuit board having an electrical circuit substantially only on the primary surface thereof;

folding the circuit board so that the primary surfaces of the first and second sections thereof are substantially non-coplaner;

forming a base plate having an opening therethrough for allowing the transducer to be positioned for exposure to an environment of which the predetermined environmental condition is to be sensed;

mounting the circuit board relative to the base plate so that the second section of the circuit board is adapted to position the transducer for exposure to said environment through the opening in the base plate.

14. The method of claim 13 wherein the step of folding the circuit board comprises folding the second section of said board substantially 180°

relative to the first section thereof so that the primary surfaces of the first and second sections of said board face outwardly from one another.

15. The method of claim 14 wherein:

the steps of forming the circuit board and securing the circuit board to the base plate are effective to position the transducer so that it extends through the opening in the base plate; and

the step of forming the base plate includes forming a protective shield, having an inside and an outside, around the opening on a side of the base plate opposite that on which a cover assembly is to be mounted to form a protected region around the sensor location.

16. The method of claim 15 wherein the protective shield is in the form of a hollow projection extending from the base plate, and having at least one opening between the inside and outside thereof.

17. The method of claim 16:

wherein the step of forming the circuit board comprises forming a circuit having at least one user adjustable component on the primary surface of the second section of the circuit board; and

including the further step of securing a cover assembly to the base plate to enclose the circuit board, the cover assembly having an aperture therein through which the user adjustable component is accessible.

18. The method of claim 17 wherein:

the transducer is a humidity sensor;

the electrical circuit on the second section of the circuit board is adapted to provide an output signal determined, in part, by a humidity value sensed by the humidity sensor; and

the user adjustable component of the electrical circuit is effective to input a humidity set point which, in part, determines the output signal of said circuit.

19. The method of claim 18 wherein:

the circuit board is formed with at least one signal terminal thereon; and

the cover assembly includes a first cover having a first opening therethrough through which the user adjustable component is accessible and having at least a second opening therethrough through which the signal terminal is accessible, the cover assembly further including a second cover having an opening therethrough through which the user adjustable component is accessible.

20. In a humidistat of the type having a humidity sensor located for exposure to air on one side of a barrier, the humidity sensor being mounted on a circuit board carrying circuitry for producing an output signal dependent on the humidity value sensed by the humidity sensor and on a humidity set point determined by a user set point control accessible from the side of the barrier opposite the location of the humidity sensor, the improvement which comprises:

a base plate having first and second oppositely facing principal surfaces and an opening therethrough;

a hollow protective shield, having an inside and outside, surrounding the opening through said base plate projecting from the first principal surface thereof, said hollow protective shield having at least one opening between the inside and outside thereof; and

a printed circuit board having a primary surface and including first and second sections joined by at least one flexible jumper, the first section holding a humidity sensor in electrical communication with the flexible jumper, the second section of the printed circuit board carrying a circuit for receiving a signal communicated from the humidity sensor through the flexible jumper, the first section of the printed circuit board being folded so the primary surfaces of the first and second sections thereof are substantially non-coplaner, said printed circuit board being mounted so that the first section thereof is positioned proximate the second principal surface of said base plate and so that the humidity sensor is positioned on the base plate within said protective shield.

21. The apparatus of claim 20 wherein:

the first section of the printed circuit board is folded substantially 180°

relative to the second section thereof so that the primary surfaces of the first and second sections of said printed circuit board face outwardly from one another.

22. An apparatus for converting a sensed value of an environmental condition to an electrical variable, comprising:

a circuit board having a primary surface, comprising;

a transducer disposed on the primary surface of said circuit board for sensing a predetermined environmental condition;

an electrical circuit disposed substantially on the primary surface of said circuit board, the circuit in electrical communication with the transducer;

a base plate having first and second oppositely facing principal surfaces and an opening therethrough, said circuit board positioned relative to said base plate so that the transducer is positioned for exposure to said environment through the opening in said base plate.

23. The apparatus of claim 22 wherein:

said circuit board comprises first and second sections joined by at least one flexible jumper, the first section of the circuit board being adapted to hold the transducer in electrical communication with said flexible jumper, the second section of the circuit board carrying the electrical circuit.

24. The apparatus of claim 23 wherein:

said circuit board is folded so that the primary surfaces of the first and second sections thereof are substantially non-coplanar.

25. The apparatus of claim 24 wherein:

said circuit board is folded substantially 180°

relative to the first section thereof so that the principal surfaces of the first and second sections of said circuit board face outwardly from one another.

26. The apparatus of claim 22 further comprising:

a protective shield, having an inside and an outside, in the form of a hollow projection extending from said base plate to form a protected region around the opening, and having at least one opening between the inside and outside thereof.

27. The apparatus of claim 22 further comprising:

a user adjustable component on the primary surface of the circuit board; and

a cover assembly secured to said base plate to enclose the circuit board, the cover assembly having an aperture therein through which the user adjustable component is accessible.

28. The apparatus of claim 27 wherein:

said circuit board further comprises at least one signal terminal; and

said cover assembly includes a first cover having a first opening therethrough through which the user adjustable component is accessible and having at least a second opening therethrough through which the signal terminal is accessible, the cover assembly further including a second cover having an opening therethrough through which the user adjustable component is accessible.

29. The apparatus of claim 22 wherein:

the transducer is a humidity sensor; and

the electrical circuit on said circuit board is adapted to provide an output signal determined, in part, by a humidity value sensed by the humidity sensor.