Smoke chamber

• US 6,778,091 B2
• Filed: 01/09/2001
• Issued: 08/17/2004
• Est. Priority Date: 01/09/2001
• Status: Expired due to Fees

• Current Assignee: Simplexgrinnell LP (Johnson Controls International plc)
• Original Assignee: Simplexgrinnell LP (Johnson Controls International plc)
• Inventors: Prasad, Jayanthi, Qualey, James R. III, Stanley, Lawrence G., Desmarais, Louis, Brighenti, Donald D.
• Primary Examiner(s): La, Anh V.
• Application Number:
  US09/757,081
• Publication Number:
  US 20020089426A1
• Time in Patent Office: 1,316 Days
• Field of Search: 340/628, 340/630, 340/693.6, 361/756, 361/758, 250/564, 250/574, 250/554
• US Class Current: 340/628
• CPC Class Codes: G08B 17/107 for detecting light-scattering due to smoke
• CPC Class Codes: G08B 17/113 Constructional details

Abstract

A smoke detecting chamber for use in a light-scattering type smoke detector is provided which includes a chamber cover that forms one side of the smoke detecting chamber. The chamber cover includes a plurality of first baffles that prevent external light from entering the smoke chamber. The smoke detector further includes a chamber base that forms another side of the smoke detecting chamber, the chamber base including a plurality of second baffles that intermesh with the first baffles when the smoke detecting chamber is formed.

Claims

1. A smoke detector, comprising:

a printed circuit board having a first side and a second side;

electronic components positioned on the first side of the board;

a can for isolating the electronic components from external radio frequency emissions, the can being disposed on the first side of the board;

a smoke detecting chamber formed by a chamber cover and a chamber base, the smoke detecting chamber being positioned on the second side of the board, the chamber base including an annular ramp;

an optical bench disposed between the second side of the board and the smoke detecting chamber;

an emitting device held by the optical bench that emits radiation into the smoke chamber; and

a sensing device held by the optical bench that senses radiation from the emitting device when smoke fills the smoke detecting chamber.

2. The detector of claim 1, wherein the chamber cover includes a plurality of first baffles that prevent external light from entering the smoke detecting chamber, the baffles conforming to the ramp.

3. The detector of claim 1, wherein the chamber cover includes a plurality of first baffles that prevent external light from entering the smoke detecting chamber and wherein the chamber base includes a plurality of second baffles that intermesh vertically with the first baffles when the smoke detecting chamber is formed to prevent entry of ambient light into the smoke chamber when the base and cover are slightly misaligned or do not substantially conform to one another.

4. The detector of claim 1, wherein at least one projection projects from the chamber base, said projection comprising a snap-fit that engages with a respective retaining member of the chamber cover.

5. The detector of claim 4, wherein the projection includes a light emitting device.

6. The detector of claim 4, wherein the projection includes a temperature measuring device.

7. The detector of claim 1, wherein the chamber cover includes a plurality of circumferential grooves facing the smoke detecting chamber for controlling propagation of stray external light and radiation from the emitting device.

8. The detector of claim 7, wherein the plurality of circumferential grooves are V-shaped grooves with one face of each groove angled approximately 30 degrees relative to a chamber axis.

9. The detector of claim 1, wherein the emitting device and the sensing device are held by crush ribs of the optical bench.

10. The detector of claim 1, further comprising a second can covering a back side of the sensing device.

11. The detector of claim 1, wherein the optical bench is removably attached to the chamber base.

12. A smoke detecting chamber for use in a light-scattering type smoke detector, comprising:

a chamber cover forming one side of the smoke detecting chamber, the chamber cover including a plurality of first baffles that prevent external light from entering the smoke chamber; and

a chamber base forming another side of the smoke detecting chamber, the chamber base including a plurality of second baffles that vertically intermesh with the first baffles when the smoke detecting chamber is formed when the base and cover are slightly misaligned or do not substantially conform to one another.

13. The chamber of claim 12, wherein the chamber base includes an annular ramp.

14. The chamber of claim 12, wherein the chamber cover removably attaches to the chamber base.

15. The chamber of claim 14, wherein the chamber base includes a first projection and a second projection formed thereon that engage with respective retaining members of the chamber cover.

16. The chamber of claim 15, wherein the first projection includes a light emitting device.

17. The chamber of claim 15, wherein the second projection includes a temperature measuring device.

18. The chamber of claim 12, wherein the chamber cover includes a plurality of circumferential grooves facing the smoke detecting chamber for controlling propagation of stray external light.

19. The chamber of claim 18, wherein the plurality of circumferential grooves are V-shaped grooves with one face of each groove angled approximately 30 degrees relative to a chamber axis.

20. A smoke detector, comprising:

a printed circuit board having a first side and a second side;

electronic components positioned on the first side of the board;

a can for isolating the electronic components from external radio frequency emissions, the can being disposed on the first side of the board;

a smoke detecting chamber formed by a chamber cover and a chamber base, the smoke detecting chamber being positioned on the second side of the board, the chamber cover including a plurality of first baffles that prevent external light from entering the smoke chamber, the chamber base including a plurality of second baffles that intermesh vertically with the first baffles when the smoke detecting chamber is formed to prevent entry of ambient light into the smoke chamber when the base and cover are slightly misaligned or do not substantially conform to one another;

an optical bench disposed between the second side of the board and the smoke detecting chamber;

an emitting device held by the optical bench that emits radiation into the smoke chamber; and

a sensing device held by the optical bench that senses radiation from the emitting device when smoke fills the smoke detecting chamber.

21. The detector of claim 20, wherein the chamber base includes a first projection and a second projection, each projection extending from the chamber base and engaging respective retaining members of the chamber cover to removably secure the chamber cover on the chamber base, the first projection and the second projection being asymmetrically positioned on the chamber base.

22. A smoke detecting chamber for use in a light-scattering type smoke detector, comprising:

a chamber cover forming one side of the smoke detecting chamber, the chamber cover including first means for preventing external light from entering the smoke chamber; and

a chamber base forming another side of the smoke detecting chamber, the chamber base including second means that vertically intermesh with the first means when the smoke detecting chamber is formed for preventing external light from entering the smoke chamber to prevent external light from entering the smoke chamber when the base and cover are slightly misaligned or do not substantially conform to one another.

23. A method of preventing light from entering a smoke detecting chamber for use in a light-scattering type smoke detector, comprising:

forming one side of the smoke detecting chamber with a chamber cover, the chamber cover including a plurality of first baffles that prevent external light from entering the smoke chamber; and

forming another side of the smoke detecting chamber with a chamber base, the chamber base including a plurality of second baffles that vertically intermesh with the first baffles when the smoke detecting chamber is formed to prevent external light from entering the smoke chamber when the base and cover are slightly misaligned or do not substantially conform to one another.