Sensor and control module with improved sensor isolation

• US 5,008,775 A
• Filed: 09/11/1989
• Issued: 04/16/1991
• Est. Priority Date: 09/13/1988
• Status: Expired due to Term

• Current Assignee: Honeywell Regelsysteme GmbH (Honeywell International Inc.)
• Original Assignee: Honeywell Regelsysteme GmbH (Honeywell International Inc.)
• Inventors: Schindler, Juergen, Heinen, Hartwig
• Primary Examiner(s): Tolin, Gerald P.
• Application Number:
  US07/405,481
• Time in Patent Office: 582 Days
• Field of Search: 338/22 R, 338/25, 338/31, 236/DIG. 19, 236/46 R, 236/94, 116/216, 361/331, 361/380, 361/382, 361/383, 361/395, 361/399, 174/16.1, 374/100, 374/102, 374/114, 374/170, 374/171, 374/173, 374/183, 374/185, 374/208, 307/113
• US Class Current: 361/679.46
• CPC Class Codes: G01D 11/24 Housings ; Casings for instruments
• CPC Class Codes: G01K 1/16 Special arrangements for conducting heat from the object to the sensitive element
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor
• CPC Class Codes: H05K 5/0017 with operator interface units
• CPC Class Codes: H05K 5/0018 having an electronic display
• CPC Class Codes: Y10S 236/19 Ventilated thermostat

Abstract

A sensor and control module have a housing with an internally mounted printed circuit board which supports a sensing element located in an outwardly projecting hollow portion formed at the lower part of the housing. The projecting portion is prism-shaped and includes air intake slots at its bottom side to enable external air to reach the element. The upper side of the projecting portion which is adjacent to control elements on the module is sealed. The housing is provided with an internal air passage adjacent to the printed circuit board between the air intake slots and air exit slots at a top side of the housing spaced from the control elements. In one embodiment, the module is a thermostat, and the sensing element is a temperature responsive resistor used to sense air temperature.

Claims

1. A sensor and control module comprising a housing having air slots in the upper and lower portions, at least one sensing element located in the lower portion of said housing,

a control circuit board producing heat mounted in said upper portion and said lower portion of said housing and connected to said sensing element, at least one manually actuable control element located on an exterior surface of said housing and connected to said circuit board, whereby said housing provides a chimney effect as heat of said circuit board causes air to be drawn through said air slots of said lower portion past said sensing element and said circuit board to exit through said air slots in said upper portion.

2. A module according to claim 1 wherein said air intake slots are arranged in two sets, whereat one set is arranged in a plane in front of the plane of said circuit board and the other set is arranged in a plane behind the plane of said circuit board.

3. A module according to claim 2 wherein said circuit board only extends over a portion of an internal width of said housing and that said air exit slots each are arranged laterally at the upper side of said housing.

4. A module according to claim 1 wherein said sensing element is a temperature responsive resistor.

5. A module according to claim 1 wherein said control elements include a plurality of manually actuable switches and an LCD display.

6. A module according to claim 1 wherein said housing includes a cover having said projection formed therein and a base plate means for supporting said cover and mounting the module on a surface.

7. A module according to claim 1 further comprising a hollow outwardly extending projection of said housing containing said sensing element, said projection located on the front side and in the lower portion of said housing, wherein said projection includes said intake slots in its lower portion and is sealed in its upper side.