BACKGROUND
This application relates to smoke detectors, and more particularly
photoelectric smoke detectors.
A photoelectric smoke detector includes a light source and a photoelectric
5 receiver to detect whether or not smoke is present. Smoke is determined to be
present when a change in the amount of light received at the photoelectric receiver
exceeds a pre-determined value. Upon the smoke detector determining smoke is
present, a fire alarm is tripped.
10 SUMMARY
A photoelectric smoke detector, according to an example of this disclosure
includes an optics cover that provides a smoke chamber that has a smoke chamber
opening, a CO detector is mounted to the optics cover. An inner cover provides a
first opening and a second opening. The first opening receives a portion of the CO
15 detector and the second opening is aligned with the smoke chamber opening. A
spoiler includes a U-shaped fin arrangement and is received against the inner
cover.
In a further example of the foregoing, the second opening has a contour
substantially the same as a contour of a lip of the optics cover that provides the
20 smoke chamber opening.
In a further example of any of the foregoing, the first opening is
substantially T-shaped.
In a further example of any of the foregoing, the second opening is
substantially D-shaped.
25 In a further example of any of the foregoing, the inner cover includes a
divider portion that separates the first opening from the second opening.
In a further example of any of the foregoing, the U-shaped fin portion
abuts the divider portion.
In a further example of any of the foregoing, the inner cover includes first
30 and second projections angled to create a tapered path across an outer portion of
the inner cover.
3
In a further example of any of the foregoing, the spoiler includes a ring
portion, and a conical portion that extends from the ring portion. The U-shaped fin
arrangement extends from the conical portion.
In a further example of any of the foregoing, the conical portion tapers as
5 it extends toward the optics cover.
In a further example of any of the foregoing, an outer cover is attached to a
base portion, and the outer cover includes an open entry portion.
In a further example of any of the foregoing, a gap is provided between the
CO detector and the outer cover. The inner cover seals the gap from the entry
10 portion to prevent smoke particles from entering the gap.
In a further example of any of the foregoing, the entry portion includes a
first row of openings, a second row of openings, and a third row of openings. A
bottom surface of the inner cover is flush with an upper surface of the first row of
openings.
15 In a further example of any of the foregoing, an outer edge of the spoiler is
received against a horizontal bar between the second row of openings and the
third row of openings.
In a further example of any of the foregoing, the inner cover is heat staked
to an outer cover.
20 In a further example of any of the foregoing, the inner cover is snap-fit to
an outer cover.
In a further example of any of the foregoing, bug screen is positioned over
the smoke chamber opening.
In a further example of any of the foregoing, the U-shaped fin arrangement
25 extends to a plane that is provided at an outer lip of the smoke chamber, and the
outer lip provides the smoke chamber opening.
In a further example of any of the foregoing, the U-shaped fin arrangement
is open toward the CO detector.
In a further example of any of the foregoing, the U-shaped fin arrangement
30 includes a first fin portion substantially parallel to the top of a central axis of the
4
CO detector. A second fin portion and a third fin portion are substantially parallel
to the second fin portion.
A photoelectric smoke detector according to an example of this disclosure
includes a base portion, a circuit received on the base portion, an optics cover that
5 is mounted to the base portion and provides a smoke chamber that has a smoke
chamber opening. A CO detector is mounted to the optics cover. An inner cover
provides a first opening and a second opening. The first opening receives a
portion of the CO detector and the second opening is aligned with the smoke
chamber opening. A spoiler includes a ring portion, a conical portion that extends
10 from the ring portion toward the smoke chamber, and a U-shaped fin arrangement
that extends from the conical portion. The spoiler is received against the inner
cover. An outer cover is attached to a base portion. The outer cover includes an
open entry portion. A gap is provided between the CO detector and the outer
cover, and the inner cover seals the gap from the entry portion to prevent smoke
15 particles from entering the gap.
These and other features may be best understood from the following
specification and drawings, the following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
20 Figure 1 illustrates a prior art smoke detector.
Figure 2 illustrates an example smoke detector.
Figure 3 illustrates an example inner cover of the example smoke detector
of Figure 2.
Figure 4 illustrates a portion of the example smoke detector of Figure 2.
25 Figure 5 illustrates a cross sectional view of the example smoke detector.
Figure 6 illustrates an example spoiler for the example smoke detector.
Figure 7 illustrates a cross sectional view of the example smoke detector.
Figure 8 illustrates the example spoiler of Figure 6 received within an
example outer cover.
30 Figure 9 illustrates the example inner cover of Figure 3 received within the
example outer cover.
5
Figure 10 illustrates a performance graph of the prior art smoke detector of
Figure 1.
Figure 11 illustrates a performance graph of the example smoke detector.
5 DETAILED DESCRIPTION
Figure 1 illustrates a prior art smoke detector 20. A base portion 22 for
mounting to a surface, such as a ceiling in some examples, is provided. An optics
cover 24 is attached to the base portion 22 and provides a smoke chamber 26.
The example smoke detector 20 is a photoelectric smoke detector. In a
10 photoelectric smoke detector, a light source (not shown) is aimed into the smoke
chamber 26 at an angle away from a receiver (not shown). When smoke enters the
chamber 26, smoke particles scatter the light from the light source onto the
receiver, which then triggers an alarm. In some examples, the smoke detector 20
is a multi-wave multi-angle photoelectric smoke detector, as is known to include
15 multiple photoelectric elements, such as several light sources and/or several
receivers, to allow for multiple different types of signals.
A carbon monoxide (CO) detector 28 is mounted to the optics cover 24
outside of the smoke chamber 26 for detecting the presence of carbon monoxide.
An outer cover 30 attaches to the base portion 22 but is shown as removed from
20 the base portion 22 for ease of viewing. The outer cover 30 includes an open
entry portion 32 for allowing smoke particles to enter the smoke detector 20 for
detection. A circuit board 33 may be provided between the optics cover 24 and
the base portion 22 to mechanically support and electrically connect electronic
components of the smoke detector 20. The smoke detector 20 may include one or
25 more inserts (not shown) for directing smoke particles from the entry portion 32
into the smoke chamber 26.
Directional orientations in this disclosure such as “above,” “below,” “top,”
“bottom,” and the like are made with reference to ceiling mounted smoke
detectors, but one of ordinary skill in the art having the benefit of this disclosure
30 would recognize that smoke detectors mounted in other orientations may also
benefit.
6
Applicant has identified that when smoke enters in certain directions of
entry, such as directions of entry near the CO detector 28, prior art smoke
detectors 20 are less efficient at directing smoke into the smoke chamber 26 for
detection than when smoke enters from other directions.
5 Figure 2 illustrates an improved smoke detector 120. It should be
understood that like reference numerals identify corresponding or similar
elements throughout the several drawings. An inner cover 134 and a spoiler 136
are provided in the smoke detector 120 to uniformly direct smoke particles
entering the smoke detector from all directions into the smoke chamber 126 and to
10 prevent smoke particles from entering gaps outside of the smoke chamber 126.
In some examples, as shown, the inner cover 134 provides an opening 138
contoured to receive a portion of the CO detector 128 and an opening 140
positioned to align with the opening 142 of the optics cover 124. In some
examples, as shown, the opening 138 is substantially T-shaped to accommodate
15 two differently sized cylindrical portions of the CO detector 128. Other shapes
may be used to accommodate differently shaped CO detectors in some examples.
In some examples, as shown, the opening 140 has substantially the same contour
as the opening 142. In some examples, as shown, the openings 140, 142 are
substantially D-shaped. In some examples, as shown, the lip 143 of the opening
20 142 has substantially the same contour as the perimeter of the opening 140. Other
shapes may be utilized to accommodate differently shaped smoke chambers in
some examples. In some examples, a porous bug screen 144 may be placed over
the opening 142 to prevent insects and the like from entering the smoke chamber
126.
25 The outer cover 130, the inner cover 134, and the spoiler 136 are shown in
exploded form for ease of viewing, but, when assembled, the inner cover 134 is
received against the CO detector 128 and the optics cover 124, and the spoiler 136
is received against the inner cover 134. As discussed further below, in some
examples, the inner cover 134 may be attached to an inner surface of the outer
30 cover 130.
7
In some examples, the inner cover 134 and the spoiler 136 are made of
thermoplastic materials. In some examples the inner cover 134 and the spoiler 136
are made of acrylonitrile butadiene styrene (ABS).
Figure 3 illustrates the inner cover 134 shown in Figure 2. The inner cover
5 134 includes an outer portion 146 providing an outer edge 148. The outer edge
148 of the inner cover 134 is shaped to be received by the outer cover 130 as
described below with reference to Figure 5. In some examples, the outer portion
146 may have a taper. In some examples, such as the example of Figure 3, outer
portion 146 may provide a circular outer edge 148 and the outer portion 146 may
10 have a conical taper. A dividing portion 150 separates the opening 138 from the
opening 140. The inner cover 134 may further include projections 152 extending
from a bottom surface 154. The inner cover 134 may be positioned about a central
axis A1 relative to the outer edge 148 in some examples. As shown, the axis A1
extends through the opening 140 in some examples. The inner cover 134 may
15 include a light pipe aperture 155 for receiving a light pipe indicator 157 (see
Figure 4).
Figure 4 illustrates the inner cover 134 received against the optics cover
124. The bottom surface 154 faces away from the base portion 122 when
assembled. In some embodiments a light pipe 157 received into the inner cover
20 134 may direct light from within the detector 120, such as from a light-emitting
diode or other light source, to the outside of the detector 120, or may direct light
received from outside of the detector 120 to a sensor or other device within the
detector 120 and above inner cover 134. The inner cover 134 is received in
abutment against the lip 143 (not shown; see Figure 2) and the CO detector 128,
25 such that smoke particles moving across the bottom surface 154 are directed
toward the smoke chamber 126.
As shown schematically, smoke particles S1, S3 entering the smoke
detector 120 move across the bottom surface 154 of the inner cover 134 and into
the smoke chamber 126. Smoke particles S2 entering in directions near the CO
30 detector 128 move across the bottom surface 154 and the bottom surface 156 of
the CO detector 128 before entering the smoke chamber 126. The projections 152
8
are angled to direct smoke particles S2 toward the smoke chamber 126 by
providing a tapered path across the bottom surface 154 of the outer portion 146 of
the inner cover 134 before the particles move over the CO detector 128. The
inner cover 134, the optics cover 124, and CO detector 128 are engaged in a
5 sealing manner to prevent gaps within the smoke detector 120 but outside of the
smoke chamber 126 that may trap smoke S1, S2, S3 outside of the smoke
chamber 126.
Figure 5 illustrates a cross-sectional view of the example smoke detector
120. The outer edge 148 of the inner cover 134 is received against the inner
10 surface 158 of the outer cover 130 to prevent smoke from entering gaps other than
the smoke chamber 126, such as the gap 160 between the CO detector 128 and the
outer cover 130 in some examples. In some examples, as shown, the bottom
surface 154 of the outer portion 146 is substantially flush with the upper surface
162 of the entry portion 132.
15 As shown schematically in Figure 5 with reference back to Figure 4,
smoke particles S2 may move across a ceiling C, down the outer surface of the
outer cover 130, into the smoke detector 120 through the entry portion 132 and
across the surface 162, across the bottom surface 154 at the outer portion 146,
across the CO detector 128, across the bottom surface 154 at the dividing portion
20 150 and into the smoke chamber 126. Some smoke particles may deflect off a fin
164 of the spoiler 136 toward the smoke chamber 126, as discussed further below.
Figure 6 illustrates the spoiler 136 oriented in the upward direction U as it
would be within a ceiling mounted configuration of the smoke detector 120. Fins
166 and 168 connect to and extend from the fin 164 to form a U-shaped fin
25 arrangement 170. The U-shaped fin arrangement 170 is positioned to be open
toward the CO detector 128 (see Figure 5). That is, the open side of the U-shaped
fin arrangement 170 is nearer the CO detector 128 than the fin 164. One or more
of the fins 164, 166, 168 of the U-shaped fin arrangement 170 may include
straight portions.
30 The spoiler 136 includes a ring portion 172 and a conical portion 174
extending upwardly from the ring portion 172. The U-shaped fin arrangement
9
170 extends from the conical portion 174. The spoiler 136 provides an opening
176 inward (relative to the outer edge 178) of the U-shaped fin arrangement 170.
The U-shaped fin arrangement 170 is open toward a void 177 in the conical
portion 174 that extends from the opening 176. The ring portion 172 includes an
5 outer edge 178, which may have a number of notches 180 for receiving posts (not
shown) of the entry portion 132. The ring portion 172 may be positioned about a
central axis A2. In the illustrative example, when assembled the axis A2 of the
ring portion 172 aligns with the axis A1 of the outer portion 146 (see Figure 3).
The spoiler 136 may include a light pipe groove 181 for receiving a light pipe
10 indicator 157 (shown in Figure 4).
As shown schematically in Figure 6 with reference back to Figures 4 and
5, smoke particles S2 may deflect off the fin 164 and into the smoke chamber 126
(not shown). Smoke particles S4 may move along the ring portion 172 and
conical portion 174 and deflect off the fin 168 and upward into the smoke
15 chamber 126. Smoke particles S5 may move along the ring portion 172 and
conical portion 174 and deflect off the fin 166 and upward into the smoke
chamber 126. Smoke particles S6 may move along the ring portion 172 and
conical portion 174 and deflect off the fin 164 and upward into the smoke
chamber 126.
20 Figure 7 shows a cross sectional view of the example smoke detector 120,
showing smoke particle paths S5 and S6, with reference to Figure 6. As shown,
the example conical portion 174 tapers as it extends upward toward the smoke
chamber 126 to form a continuous surface from the entry portion 132 to the
leading edge of the chamber 126. The outer edge 178 of the spoiler 136 is
25 received against the inner surface 158 of the outer cover 130 at the entry portion
132. In some examples, as shown, the entry portion 132 provides three rows of
openings 182A, 182B, and 182C, and the edge 178 is received against the
horizontal bar 184 between the lower two rows 182B and 182C. In some
examples, as shown, the fins 164, 166, 168 extend to a plane P at the lip 143 of
30 the smoke chamber 126. In some examples, as shown the bug screen 144 may be
positioned along the plane P. Other heights can be utilized in some examples. The
10
fins 164, 166, 168 extend from the conical portion 174 upward toward the smoke
chamber 126.
Figure 8 illustrates the spoiler 136 received against the bar 184 of the entry
portion 132 of the outer cover 130. The notches 180 receive the posts 186 of the
5 entry portion.
Figure 9 illustrates the inner cover 134 attached to the outer cover 130. In
some examples, the inner cover 134 is heat staked to the outer cover 130. In some
examples, the inner cover 134 is snap fit to the outer cover 130. In some
examples, the inner cover 134 includes tabs 188 for attachment to the outer cover
10 130.
When assembled, the fin 164 is substantially parallel to the central axis A3
of the CO detector 128 (not shown). In some examples, as shown, the fins 166
and 168 are substantially parallel to one another. As shown, the projections 152
provide a tapered path toward the opening of the U-shaped fin arrangement 170.
15 The void 177 is positioned within the same circumferential region as the CO
detector 128 (not shown). The ends of the fins 166, 168 may be received against
the dividing portion 150. The outer cover 130 may be positioned relative to a
central axis A4, such that the axes A1, A2, and A4 are substantially aligned.
The example smoke detector 120 utilizes Brownian motion principles for
20 the motion of smoke particles within air. Brownian principles describe the ability
of small smoke particles to remain suspended due to interactions with the
atmosphere with motions that are energetic enough to resist the pull of gravity
which would force these particles to fall to earth. The inner cover 134 seals gaps
and prevents smoke particles from settling within the gaps instead of moving into
25 the smoke chamber 126. The placement and angling of the various surfaces, fins,
and projections of the inner cover 134 and spoiler 136 in the illustrative example
direct smoke particles into the smoke chamber 126 in an improved, uniform
manner relative to the prior art. Detection among various angles of entry relative
to the horizontal plane of the smoke detector 120 is more uniform as compared to
30 prior art smoke detectors.
11
Figure 10 illustrates a graph, for the various positions shown in the
horizontal plane P2 of the prior art smoke detector 20, of smoke in air denoted by
obscuration per foot (OBS/ft) against the analog signal converted to a digital
output (AD) of refracted light detected by the photodiode from the forward scatter
5 infrared LED. The Forward (F) infrared (IR) LED emits radiation in the smoke
chamber 26 and some of this radiation is scattered in the forward direction
towards the photodiode which is a direct function of obscuration % of smoke.
Each of the curves represent the behavior of a single smoke detector for its
specified angle of entry of the smoke path into the prior art smoke detector 20. A
10 wide variation of signal response is observed. That is, as seen, there was
significant variance of detection among the various angles of entry into the prior
art smoke detector 20.
Figure 11 illustrates a similar graph for the corresponding various
positions in the horizontal plane P3 of the example smoke detector 120. As seen,
15 there was more uniform detection between the various angles of entry into the
example smoke detector 120. The inner cover 134 and the spoiler 136 of the
illustrative example facilitate a uniform signal regardless of orientation of smoke
entry into the example smoke detector 120. Thus, the detector 120 is more
equally sensitive in all orientations. One of ordinary skill in the art having the
20 benefit of this disclosure would recognize that certain modifications could be
made to the illustrative example, while still achieving similar benefits.
Although the different examples are illustrated as having specific
components, the examples of this disclosure are not limited to those particular
combinations. It is possible to use some of the components or features from any
25 of the examples in combination with features or components from any of the other
examples.
The foregoing description shall be interpreted as illustrative and not in any
limiting sense. A worker of ordinary skill in the art would understand that certain
modifications could come within the scope of this disclosure. For these reasons,
30 the following claims should be studied to determine the true scope and content of
this disclosure.
12
We Claim:
1. A photoelectric smoke detector, comprising:
an optics cover providing a smoke chamber having a smoke chamber
5 opening;
a CO detector mounted to the optics cover;
an inner cover providing a first opening and a second opening, wherein the
first opening receives a portion of the CO detector and the second opening is
aligned with the smoke chamber opening;
10 a spoiler including a U-shaped fin arrangement and received against the
inner cover.
2. The smoke detector as recited in claim 1, wherein the second opening has
a contour substantially the same as a contour of a lip of the optics cover providing
15 the smoke chamber opening.
3. The smoke detector as recited in claim 1, wherein the first opening is
substantially T-shaped.
20 4. The smoke detector as recited in claim 3, wherein the second opening is
substantially D-shaped.
5. The smoke detector as recited in claim 1, wherein the inner cover includes
a divider portion that separates the first opening from the second opening.
25
6. The smoke detector as recited in claim 1, wherein the U-shaped fin portion
abuts the divider portion.
7. The smoke detector as recited in claim 1, wherein the inner cover includes
30 first and second projections angled to create a tapered path across an outer portion
of the inner cover.
13
8. The smoke detector as recited in claim 1, wherein the spoiler includes
a ring portion, and
a conical portion extending from the ring portion, and the U-shaped fin
arrangement extends from the conical portion.
5
9. The smoke detector as recited in claim 8, wherein the conical portion
tapers as it extends toward the optics cover.
10. The smoke detector as recited in claim 1, comprising an outer cover
10 attached to a base portion, wherein the outer cover includes an open entry portion.
11. The smoke detector as recited in claim 10, wherein a gap is provided
between the CO detector and the outer cover, and the inner cover seals the gap
from the entry portion to prevent smoke particles from entering the gap.
15
12. The smoke detector as recited in claim 10, wherein the entry portion
includes a first row of openings, a second row of openings, and a third row of
openings, and a bottom surface of the inner cover is flush with an upper surface of
the first row of openings.
20
13. The smoke detector as recited in claim 12, wherein an outer edge of the
spoiler is received against a horizontal bar between the second row of openings
and the third row of openings.
25 14. The smoke detector as recited in claim 1, wherein the inner cover is heat
staked to an outer cover.
15. The smoke detector as recited in claim 1, wherein the inner cover is snapfit to an outer cover.
30
14
16. The smoke detector as recited in claim 1, comprising:
a bug screen positioned over the smoke chamber opening.
17. The smoke detector as recited in claim 1, wherein the U-shaped fin
5 arrangement extends to a plane provided at an outer lip of the smoke chamber,
and the outer lip provides the smoke chamber opening.
18. The smoke detector as recited in claim 1, wherein the U-shaped fin
arrangement is open toward the CO detector.
10
19. The smoke detector as recited in claim 1, wherein the U-shaped fin
arrangement includes:
a first fin portion substantially parallel top a central axis of the CO
detector,
15 a second fin portion, and
a third fin portion substantially parallel to the second fin portion.
20. A photoelectric smoke detector, comprising:
a base portion;
20 a circuit received on the base portion;
an optics cover mounted to the base portion and providing a smoke
chamber having a smoke chamber opening;
a CO detector mounted to the optics cover;
an inner cover providing a first opening and a second opening, wherein the
25 first opening receives a portion of the CO detector and the second opening is
aligned with the smoke chamber opening;
a spoiler including a ring portion, a conical portion extending from the
ring portion toward the smoke chamber, and a U-shaped fin arrangement
extending from the conical portion, the spoiler being received against the inner
30 cover; and
15
an outer cover attached to a base portion, wherein the outer cover includes
an open entry portion, wherein a gap is provided between the CO detector and the
outer cover, and the inner cover seals the gap from the entry portion to prevent
smoke particles from entering the gap.