U.S. patent number 3,628,346 [Application Number 05/082,560] was granted by the patent office on 1971-12-21 for apparatus for indicating thermal and air velocity conditions of air in the plenum of a central air-conditioning system.
Invention is credited to Cecil G. Lagrone, Jr..
United States Patent |
3,628,346 |
Lagrone, Jr. |
December 21, 1971 |
APPARATUS FOR INDICATING THERMAL AND AIR VELOCITY CONDITIONS OF AIR
IN THE PLENUM OF A CENTRAL AIR-CONDITIONING SYSTEM
Abstract
Thermal and air velocity responsive electrical switch means
disposed in the plenum of a central air-conditioning system and
electrically connected in a signal system, the apparatus being
operable to actuate indicating or signal means calling attention to
fan and/or motor-compressor malfunction or failure.
Inventors: |
Lagrone, Jr.; Cecil G. (Bossier
City, LA) |
Family
ID: |
22171952 |
Appl.
No.: |
05/082,560 |
Filed: |
October 21, 1970 |
Current U.S.
Class: |
62/126; 62/127;
62/130; 62/158 |
Current CPC
Class: |
F24F
11/00 (20130101); F24F 2110/30 (20180101); F24F
2110/10 (20180101); F24F 11/61 (20180101); F24F
11/30 (20180101) |
Current International
Class: |
F24F
11/00 (20060101); F25b 049/00 () |
Field of
Search: |
;62/125,126,127,129,130,131,158 ;236/51,91 ;165/11 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Dea; William F.
Assistant Examiner: Ferguson; P. D.
Claims
What is claimed is:
1. In combination with a central air-conditioning unit including a
plenum, electrically energizable fan means for forcing cooled air
through said plenum at a predetermined volume and velocity for
discharge into an enclosure remotely positioned relative to said
plenum and in which air is to be maintained at a preselected cooled
temperature, electrically energizable motor-compressor means for
cooling air delivered to said plenum, a normally open thermostat
control first switch disposed in said enclosure and being preset to
close when the air temperature in said enclosure rises above said
preselected temperature, a first electric circuit including said
first switch, a first electric power source, and electrically
operable means for electrically connecting said fan and
motor-compressor means with a second power source to effect
energization thereof substantially simultaneously with the closing
of said first switch and the consequent energization of said first
circuit; and first means for indicating the malfunction or failure
of said motor-compressor means when said first switch is closed
energizing said first circuit, said fan and motor-compressor means,
said indicating means comprising:
electrically energizable first signal means;
a normally closed thermoresponsive second switch having switch
actuating sensing means disposed in said plenum, said second switch
being preset to open when the air in said plenum sensed by said
actuating means is cooled to a preselected temperature below the
preset actuating temperature of said first switch;
a second electric circuit connecting said first signal means in
series with said second switch and connected across said first
circuit; whereby
said second circuit and its said first signal means are
simultaneously energized with the closing of said first switch and
the energization of said first circuit, said first signal means and
second circuit being deenergized when said second switch opens.
2. The combination of claim 1 and:
said normally open thermostat control first switch including
manually operable means for setting said first switch to close at a
preselected temperature; and
adjustable means extending between and connecting said manually
operable means with said second switch to set said second switch to
open at an adjusted temperature below the closing temperature of
said first switch, said adjustable means being operable
simultaneously with the setting of said first switch.
3. The combination of claim 2 wherein:
said manually operable means includes a temperature setting arm on
said first switch;
a temperature setting lever on said second switch; and
flexible rod means extending between and connected with said arm
and lever.
4. The combination of claim 3 and:
a normally open time delay third switch;
means electrically connecting said third switch in series with said
second switch in said second electrical circuit;
said third switch closing at the expiration of its time delay
period to energize said second circuit and said first indicating
means when said second switch is closed.
5. The combination of claim 4 and means for indicating the
malfunction or failure of said fan means, said second indicating
means comprising:
electrical energizable second signal means;
normally closed air velocity responsive third switch means disposed
in said plenum in the path of air passing therethrough; and
a third electrical circuit connecting said second signal means and
said third switch means in series with one another and across said
first electric circuit.
6. The combination of claim 5 wherein said third switch means
includes switch actuating means comprising a sail disposed in said
path of air travel and movable thereby to open said third switch
and to thereby deenergize said third electric circuit.
7. The combination of claim 6 and:
a casing for said normally open thermostat control first switch;
and
means in said casing to receive and support said first and second
signal means.
8. The combination of claim 7 wherein:
said first and second signal means comprise electrcially
energizable lights.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
In accordance with the present classification of inventions as
established by the U.S. Pat. Office, it is believed that this
invention would be classified in the main class of "Refrigeration"
class 62 and, more specifically, in its subclass 129 relating to
condition sensing indicators.
2. Description of the Prior Art
The prior art is replete with disclosures relating, for example, to
thermostatic control means for air-conditioning systems of all
types, and specific reference thereto need not be here given by
virtue of their widespread and substantially uniform or
conventional construction. For the purpose of this disclosure it
may be observed that most conventional central thermostatically
controlled air-conditioning sytems include air inlet means, a
motor-compressor unit (which may be self-contained), an expansion
valve, a condenser, fan or blower means for forcing air across an
evaporator or cooling coil for discharge into a plenum or main air
duct at a preselected temperature and velocity. In conventional
installations, when the thermostat switch closes it completes a
low-voltage circuit to a fan relay switch which, in turn, operates
a high-Voltage switch to connect the fan or blower with a
high-voltage power source. In a like manner, the closing of the
thermostatic switch energizes the low-voltage motor compressor
relay switch, and the latter, in turn, operates a high-voltage
switch to connect the motor-compressor in a high-voltage circuit.
The actuation of these relay switches is, substantially,
instantaneous upon the closing of the thermostatic switch.
Conventional central air-conditioning system are designed to
discharge-conditioned (cooled) air from their respective plenums at
predetermined velocities and temperatures. As a general rule, air
in the plenum is normally cooled to a temperature of 15.degree.
below the operating temperature set on the thermostatic control,
and the velocity of the conditioned air in the plenum chamber is
usually considered to be normal with an air displacement of 3,600
cubic feet of air per minute (c.f.m.) for a 3-ton air-conditioning
unit and 6,000 c.f.m. for a 5-ton unit. It thus becomes essential
to the successful operation of the air-conditioning unit that the
motor-compressor be capable of operation to reduce the temperature
of the conditioned air to the desired point, and further that the
fan or blower means be capable of delivering air at the desired
volume and velocity.
The refrigeration or air-cooling art includes many patents which
have been issued for energizIng signal means in the presence of
abnormal heating of compartments, reduced pressure in given lines,
et cetera. Examples of such alarm and signalling devices may be
found in the U.S. Pats. to Frank E. Cobb, No. 2,144,794, Carson H.
Beane, No. 2,741,099, Roscoe D. Bean, No. 2,439,331 and Charles H.
McLeay, No. 1,573,450. These patents are considered to be merely of
interest and not at all germane with respect to the present
invention which proposes to indicate, from signals generated in or
adjacent to the plenum of a conventional air conditioner, the
satisfactory or unsatisfactory working condition of the cooling
unit and fan means.
SUMMARY OF THE INVENTION
This invention relates to the provision of indicating means for
central air-conditioning systems wherein the indicators are
responsive to sensors disposed in the plenum or air duct and in the
path of the conditioned air moving therethrough. The apparatus
includes a first indicator light connected in an electric circuit
energized by the presence of voltage in the fan relay switch
circuit and which operates in response to the air velocity in the
plenum. The switch is normally closed, and remains closed until the
air-conditioning unit is energized and the velocity of the
conditioned air reaches the desired value for which the system was
designed. At that time, the switch will open causing the light to
become deenergized indicating that the blower portion of the system
is operating at its proper capacity.
The apparatus of this invention also contemplates a second
indicator light connected in an electric circuit energized by the
presence of voltage at the compressor relay switch circuit, and
this indicator light is connected in series with two series
connected switches.
One of these last mentioned switches is a thermoresponsive switch
and includes a sensor disposed in the plenum or main duct disposed
in the path of the cooled air. This switch is normally closed and
remains closed until the temperature in the plenum reaches
15.degree. below the set room control thermostat and at this
temperature it will open.
The second of these switches is a time delay switch, normally open,
and which closes at the expiration of a predetermined and timed-out
period. If the thermoresponsive and time delay switches close, the
indicator light in this series circuit will be energized, and its
illumination will indicate to the operator a malfunction or failure
in the motor-compressor unit. If at the end of the timed-out period
the light in the circuit is not energized, the lack of its
illumination indicates that the motor-compressor unit has
functioned properly.
This invention contemplates, as a further object thereof, the
provision of indicating apparatus for central air-conditioning
units as generally referred to above, and wherein the apparatus is
noncomplex in construction and assembly, inexpensive to
manufacture, and which is rugged and durable in use.
Other and further objects and advantages of the present invention
will become manifest from a consideration of the following
specification when read in conjunction with the annexed
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view, partly in cross section,
and illustrating the apparatus forming the system comprising this
invention;
FIG. 2 is a front elevational view of the room control thermostat
shown in FIG. 1, the cover of the thermostat having been
removed;
FIG. 3 is a perspective view of the thermoresponsive switch and of
the air velocity responsive switch means; and
FIG. 4 is a schematic wiring diagram illustrating the electric
circuitry involved in the apparatus of this system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As has been heretofore stated, the instant invention is concerned
with the provision of apparatus forming a system to be used in
conjunction with a central air-conditioning system of conventional
design and construction. For the purposes of brevity and clarity,
the annexed drawings illustrated only those portions of such a
system as are relevant to the invention, it being taken for granted
that such systems and their components are old and well known.
Thus, reference numeral 10 (see FIGS. 1, 2 and 4) designates,
generally, the room control thermostat for a central
air-conditioning system, and the system further includes, as
components not illustrated, an electrically driven motor-compressor
and fan. When the system is energized, cool air is delivered to the
plenum or main air duct 12 (see FIG. 1) at a desired temperature
and velocity. In a conventional 3-ton system and 5-ton system, the
duct 12 is sized to deliver 3,600 and 6,000 cubic feet of air,
respectively, per minute.
Now the compressor and fan or blower in such a system are energized
and deenergized in response to the position of certain electrical
relay switches disposed in a control box 14 (see FIG. 4) normally
located on or adjacent to the air-conditioning equipment. The
air-conditioning control box 14 usually includes two separate
normally open relay switches; one relay switch, schematically
illustrated and assigned the reference numeral 16, controls the
energization and deenergization of the fan or blower (not shown)
and includes the terminals 18, 20. The other relay switch, also
schematically illustrated and bearing the reference numeral 22,
controls the energization and deenergization of the
motor-compressor (not shown) and is provided with the terminals 24,
26.
The air-conditioning control box 14 also houses a conventional
electric power voltage step down transformer (not shown) which has
its primary winding connected with a main power source through the
main lines 28, 30, and its secondary winding furnishing 24
volts.
The wires 32, 34 (see FIGS. 1 and 4) connect the thermostat switch
36 of the thermostat 10 in any suitable and conventional electric
circuit (not shown) which includes the transformer's secondary and
the relays' pairs of terminals 18, 20 and 24, 26, respectively, for
applying the low voltage (24 volts) across each pair thereof when
the thermostat 10 calls for cooling. The relay switches 16, 22 are
usually electromagnetic (although any conventional relay switch may
be employed) and upon the closing of the normally open thermostatic
switch 36, the windings (not shown) of the relay switches 16, 22
become instantly energized causing these switches to close and to
close high-voltage switches (not shown) connecting the fan and
motor compressor with a high-voltage power source to effect the
energization of the fan and motor-compressor.
When the thermostat 10 no longer calls for heat, its switch 36
opens thereby opening the secondary circuit effecting the
consequent loss of voltage across the terminals 18, 20 and 24, 26
respectively. With the disappearance of the secondary voltage, the
relay switches 16 22 are deenergized and open, and as these open,
the high-voltage switches open causing the deenergization of the
motor-compressor and fan or blower.
The foregoing description relates to conventional central
air-conditioning apparatus, its operation and function--all well
known in the art. However, this background information is essential
to the understanding of the present invention for the apparatus of
the system constructed in accordance with the teaching of this
invention depends, in part, upon the presence or absence of voltage
across the pairs of terminals 18, 20 and 24, 26, respectively.
The thermostat may be wall mounted, if desired, in any location
suitable to the user and wherein it is clearly visible in order to
serve a function to be described. The thermostat 10 includes a
housing 38 in which the thermostatic switch 36 is suitably encased
and supported. As is seen in the drawings, the housing 38 comprises
a back wall 40 from which laterally and forwardly project an
opposed pair of top and bottom walls 42, 44, and an opposed pair of
sidewalls 46, 48, respectively.
The housing further includes mountings 50, 52 for low-voltage (24
volt) indicator lights 54, 56 to which reference will be made
further below. A U-shaped bracket is indicated at 58. The bracket
58 includes a normally upright bight 60 on which is marked a
temperature scale 62, the scale reading from 50.degree. to
80.degree.. The bight 60 is held in forwardly spaced relationship
relative to the backwall 40 by vertically spaced rearwardly
projecting legs 64, 66 having their respective outer ends fixedly
connected thereto by conventional means (not shown).
The thermostatic switch-setting arm is indicated by reference
numeral 68, the arm having an outer end portion projecting through
an upright slot 70 formed in the sidewall 48 and terminating in
handle means 72. An offset shoulder 74 is fixedly connected to the
arm 68. A pointer 76 fixedly connected to the shoulder 74 extends
longitudinally of the arm 68 in the direction of the handle means
72, and in forwardly spaced relationship relative to the arm 68.
The arm 68 passes behind the bight 60 and the pointer 76 extends in
front thereof in order that the pointer may sweep the scale 62 as
the handle means 72 is manipulated causing the thermostat switch 36
to set to operate (close) at the desired set temperature. In FIG.
2, the thermostat 10 is shown as being set for switch closing when
the room temperature is 65.degree..
A Bowden cable 78 has one end of its operating rod 80 connected to
the arm 68 intermediate the ends of the latter, and the rod 80 and
its sheath 82 extends tranversely through the bottom wall 44 with
the sheath 82 secured against movement relative thereto by
conventional means, the latter here being illustrated as the lock
nuts 84. The forward end of the thermostat 10 is closed by a
conventional front wall 85 provided with a transparent window 86
disposed forwardly of the indicator 76. The front wall 85 may also
be provided with transparent lenses, 88, 90 disposed in
juxtaposition relative to the lights 54, 56, respectively.
The Bowden cable 78 is extended to the plenum or main air duct 12
which is usually remotely located relative to the thermostat 10,
and it is within and on the plenum that certain sensing apparatus,
essential to this invention, is disposed.
In FIG. 1 the plenum or main air duct 12 is shown as being
substantially hollow and rectangular in configuration, and is
defined by the opposed pair of top and bottom walls 92, 94 and an
opposed pair of sidewalls 96, 98, respectively.
Mounted on the sidewall 96 by conventional means is a
thermoresponsive normally closed switch 100. The switch is
adjustable to open at any desired predetermined temperature, and in
the present disclosure it will be assumed that it will open at
50.degree., 15.degree., below the thermostat setting shown in FIG.
2.
The switch 100 may be selected from those of anyone of a number of
manufacturers such as, for example, switches manufactured by RANCO,
Inc., Columbus, Ohio 4,3201, as illustrated in their published
instruction sheet No. 1,771-3, OPCO, and with specific reference to
their model A30-450, which is incorporated by reference herein.
The switch 100 includes a housing 102 having a backwall 104
connected to the exterior side of the plenum sidewall 96 by
conventional fasteners 106. The sidewall 96 is formed with a
transversely extending opening 108 spanned by the backwall 104 to
receive the temperature and sensing capillary coil 110 therethrough
in such a manner as to be positioned in the path of conditioned air
in plenum 12, the path being indicated by the arrows shown in FIG.
1.
The switch front mounting panel 112 is modified to include a
bracket 114 (see FIG. 3) which receives and supports the other end
of the sheath 82 of the Bowden cable. The relative movement between
the sheath 82 and the bracket 114 is prevented by the conventional
anchor or lock nuts 116. The other end of the rod 80 is connected
with one end of a lever 118 and the other end of the lever 118 is
connected on one end of a shaft 120 having a pinion gear 122
fixedly mounted thereon for rotation therewith.
The pinion gear 122 is adapted to be received and mesh with the
socket gear 124 which, in turn, is operative to effect the setting
for the switch cutout (opening).
For expediency and convenience, one end 126 of a substantially
U-shaped hanger bracket 128 is connected to the backwall 104, the
bight portion 130 thereof spanning the coil 110 in the direction of
its axial elongation. The other end 132 of the hanger bracket 128
supports the casing 134 of a normally closed sail switch 136 from
which depends a substantially rectangular air impervious sail 138,
the sail being disposed in the plenum 12 in the path of air travel
as is indicated by the arrows in FIG. 1.
The switch 136 may be selected from many on the market, among which
is the model E28 single-pole, single-throw switch as manufactured
by the Cherry Electric Corporation, Highland Park, Ill. Brochures
of the switch are available, and the structure thereof is herein
incorporated by reference.
The sail 138 is mounted on one end of a rod 139, the other end of
the rod 139 being enlarged to form a head pivotally supported on a
pivot pin 142 mounted on a bracket 144 secured on the casing
134.
A switch actuator rod 146 extends through an opening 148 formed in
the head 140 and terminates in an abutment 150 spaced away from the
head 140 and larger than the opening 148. In the presence of an
airflow in the plenum at a preselected velocity, the sail 138 will
pivot or turn clockwise, reference being made to FIG. 1, causing
the head 140 to engage the abutment 150 to thereby draw the
actuator rod 146 outwardly and in such a manner as to effect the
opening of the switch 136 to serve a function to be described.
The switch 136 is connected in series with the light 54, the
circuit including (see FIG. 4) the terminal 18 and wire 152 to one
side of the light 54. Wire 154 connects the other side of the light
54 with one side of the normally closed sail switch 136, and the
other side of the switch 136 connects by wire 156 with the terminal
20.
Thus, when the thermostat switch 36 closes to apply a low voltage
across the terminals 18, 20 causing the fan relay to operate the
high-voltage switch connecting the fan with its power supply,
series circuit to the light 54 is energized and the light will
illuminated. Normally, the illumination of the light 54 will be
considered as fan failure or malfunction in that it signals that
the fan is not moving the desired volume of air at the desired
velocity.
It must be realized, however, that with the air conditioning shut
down, the air in the plenum is substantially static. Consequently,
when the fan is first energized, relatively small amounts of air at
a low velocity will be delivered to the plenum. However, and after
the expiration of 3 to 5 seconds, the fan of the conventional
air-conditioning system should be delivering air to the plenum in
the desired amount and velocity. Under these circumstances, the air
will impinge on the sail 138 causing it to pivot to engage the head
140 against the abutment 150, and to thus move the switch actuator
146 opening the switch 136. This deenergizes the circuit to the
light 54 and the operator now knows that the fan side of the
air-conditioning unit is working properly. Should the light 54
remain illuminated beyond a time period of 3 to 5 seconds after the
thermostat switch 36 closes, the operator will understand that the
fan side of the air-conditioning unit is improperly functioning or
has failed.
The indicating light 56, like the indicating light 54, is not
ordinarily illuminated if the motor-compressor side of the
air-conditioning system is properly functioning. The light 56 is
controlled by the thermoresponsive switch 100 described above, and
by a time delay relay switch 160. The switches 100, 160 and the
light 56 are connected in series with one another and, for the
purpose of this description, are to be considered as being normally
closed and open, respectively, when the thermostat switch 36 is
open.
The time delay switch 160 is of the type manufactured by The A. W.
Haydon Company, Waterbury, Conn., 06720, and is of the type as
published in their Catalog Time Delay Relay L41,300 series, wiring
diagram No. 4, dated July 6, 1966, Code Identification No. 82,227,
and including sheets 1 and 2 thereof. The disclosure of this time
delay switch is incorporated by reference herein, but a brief
explanation of its operation in conjunction with this invention is
provided below.
The time delay switch 160 includes an electrically energized timing
motor 162. A time delay setting pointer 168 is provided, the
pointer 168 being adapted to be set across a time scale 170 by a
knob 172. A progress pointer 174 for indicating the time remaining
is also included in the switch 160. The switch 160 is further
provided with a solenoid-type clutch 176 which, when energized,
holds the motor 162 in its timed-out period. The time delay action
of the switch 160 begins with the absence of voltage across the
clutch solenoid.
The timing motor 162 and its associated clutch 176 are disposed
within a suitable casing 177 including a backwall 178 and a front
wall 180 on which a time scale 170 is inscribed or supported. The
backwall 178 is fixedly connected to the lower end of a support
bracket 182, the upper end of the latter being secured to the
thermoresponsive switch housing 102. The casing 117 also encloses
circuitry and connectors to which reference will be made
immediately below.
Wire 184 connects one side of the motor 162 with a connector 186.
An external wire 188 connects the terminal 24 with the connector
186. A wire 190 connects the other side of the motor 162 to a fixed
switch contact 192 which is normally engaged by the switch arm 164,
as is shown in full lines in FIG. 4. The switch arm 164 connects by
wire 194 to the connector 196, and the latter, by external wires
198, 200 is connected to the terminal 26. Thus, when a voltage is
impressed across the terminals 24, 26 and with the switch arm 164
engaged in the contact 192, the motor 162 will be energized.
Wire 202 connects one side of the clutch solenoid 176 with the
terminal 24 via wire 184, connector 186, and wire 188. Wire 204
connects with the other side of the solenoid and on a connector
206. Wire 208 connects the connector 206 with the external wire 200
which, as has been stated above, connects with the terminal 26.
Thus, voltage across the terminals 24, 26 will be impressed across
the solenoid 176.
As has been stated above, the indicator light 56 is connected in
series with the temperature responsive switch 100 and the time
delay switch 160. This is accomplished by connecting one side of
the switch 100 by the external wire 210 to the wire 188 which is
connected to the terminal 24. Wire 212 connects the other side of
the thermoresponsive switch 100 with one side of the light 56.
External wire 214 connects the other side of the light 56 with the
connector 226, and the latter connects by wire 218 to the fixed
switch contact 220. When the switch arm 166 moves to its dotted
line position of FIG. 4, it connects through the wire 222 with the
connector 224 and with the external wire 200. Mention has been made
of the fact that the wire 200 is connected with the terminal
26.
Thus, with voltage impressed across the terminals 24, 26 and with
the switch arm 166 in its dotted line position shown in FIG. 4, the
light 56 will be energized assuming that the thermoresponsive
switch 100 is closed.
These then are the elements of this invention and the indicating
system operates in the following manner.
Let is be assumed that the thermostat has been installed in a room
or other enclosure and that the temperature of the ambient air
therein is to be controlled by the conventional air-conditioning
system. The operator will set the switch 36 of the thermostat 10 by
moving the arm 68 and the pointer 76 in such a manner that the
pointer will register against the temperature sought to be
maintained in the room. In the embodiment herein illustrated, this
temperature is indicated as being 65.degree.. As the arm 68 is set
by manipulation of the handle 72, the rod 80 of the Bowden cable 78
will shift, in one direction or the other as indicated by the
arrows in FIG. 3, causing the lever 118 to pivot in the same
direction and to effect the setting of the thermoresponsive switch
100.
As has been remarked above, the thermoresponsive switch 100 is
normally closed, and is adjusted to open when the capillary tube
110 senses a temperature in the plenum 12, 15.degree. below the set
temperature of thermostat 10.
Let it now be assumed that the thermostat 10 senses a temperature
in the room above 65.degree.. This will cause the thermostat switch
36 to close, and with the closing of this switch a voltage is
impressed across the fan and motor-compressor relay switch
terminals 18, 20 and 24, 26, respectively, all in the manner
explained above. The fan and motor-compressor of the
air-conditioning unit should now substantially instantly be
activated.
The indicator light 54 connected in the fan relay switch circuit
will now be immediately energized since the sail switch 136 is
normally closed. The light 54 will remain illuminated for a short
interval of time, usually not more than 5 seconds, if the fan is
operating properly delivering air to the plenum 12 in the desired
quantity and velocity. As this air builds up to its required
velocity, its impingement against the sail 138 will cause the same
to pivot and to thereby open the switch 136. This air build up time
usually takes not more than 5 seconds if the fan is operating
properly. If the light 54 remains energized longer than this time
period, the operator should then check the fan side of the
air-conditioner unit for malfunction or failure.
When the thermostat switch 36 opens indicating that the air in the
room to be conditioned has reached its temperature of 65.degree.,
voltage across the terminals 18, 20 will disappear (as will voltage
across the terminals 24, 26) and the air-conditioner unit ceases to
function. With the air in the duct 12 now no longer moving, the
sail switch will pivot in a reverse direction to depend
substantially vertically in its position shown in FIG. 1, thereby
again closing the sail switch 136.
When the temperature of the air in the room in which the thermostat
10 is installed causes the switch 36 to close and effect actuation
of the air-conditioning equipment, voltage is also applied across
the terminals 24, 26. It must now be borne in mind that the
thermoresponsive switch 100 is normally closed since the air in the
plenum 12 before the air conditioner is activated will be at a
higher temperature than the 50.degree. temperature for which the
switch 100 has been preset to open.
Assuming that the switch 100 is closed at the time of the operation
of the air-conditioning unit is initiated, the switch arm 166 will
be in its open position shown in full lines in FIG. 4. The series
circuit to the light 56 is, thus, open.
Upon the closing of the thermostat switch 36, voltage will be
impressed across the terminals 24, 26 causing the motor-compressor
side of the air-conditioning unit to become activated. This voltage
is also impressed across the motor 162 to energize the same as well
as the solenoid clutch 176 to initiate the timed-out or time delay
period. In the present case, the timing mechanism is assumed to be
set for a 15 minute time delay. The switch arms 164, 166 are in
their full line positions and will so remain until the expiration
of the time delay period. The temperature of the air in the plenum
will be above 50.degree. and, consequently, the thermoresponsive
switch 100 will be closed. However, since the switch arm 166 is not
engaged with the contact 220, the circuit to the light 56 is not
energized immediately upon the appearance of voltage across the
terminals 24, 26. When the thermostat switch 36 closes to effect
the operation of the motor-compressor unit, air in the conduit 12
will commence cooling. If the motor-compressor unit is working
properly, the temperature in the plenum 12 will be reduced and when
it reaches 50.degree., the thermoresponsive switch 100 will open.
This cooling operation normally requires approximately 15 minutes
and corresponding to the time delay period set on the switch
160.
If the air in the plenum 12 cools to 50.degree. within the 15
minute time period, the thermoresponsive switch 100 will open and
the light 56 will not be energized.
However, if at the end of the 15 minute interval of time delay, the
switch 100 is still closed and the time delay switch 160 operates,
the switch arm 166 will close against the contact 220 and thereby
complete the series circuit to the light 56 which becomes energized
and illuminates calling attention to malfunction or failure in the
motor-compressor unit.
The switches 100, 160 will hold in their described closed positions
after the expiration of the time interval and until the air in the
plenum 12 reaches 50.degree. and the temperature of the ambient air
in the room in which the thermostat is located cools to 65.degree.,
and when these conditions have been reached the switch 36 will open
and take the circuit to the terminals 24, 26.
But the continued illumination of the light 56 after the expiration
of the time delay period should give the operator some concern if,
after checking motor-compressor unit and finding the same to be
satisfactory, the light 56 remains lit.
When the air in the room to be air conditioned reaches 65.degree.,
the thermostat switch 36 opens and deenergized the motor 162 and
the clutch solenoid 176 causing the timer to instantly reset to its
15 minutes time delay interval.
The indicating system according to this invention finds further
utility in connection with air-conditioning systems when the
weather is mild and the air-coniditioning system need not operate
at full capacity or rather infrequently. For example, let it be
assumed that the apparatus of this invention is in its illustrated
and described positions and conditions prior to the closing of the
thermostat switch 36.
When the thermostat switch 36 closes to effect actuation of the
air-conditioning equipment, the motor 162 is energized as well as
the clutch solenoid 176 to initiate the time delay period, all in
the manner described above. The switch 100 will be closed, but the
light 56 will not be energized because the switch air 166 has not
moved against the contact 220.
Now if the air in the room controlled by the thermostat 10 cools to
65.degree. in the time period of less than 15 minutes, the switch
36 opens, breaking the circuit to the terminals 24, 26 thereby
deenergizing the motor 162 and the clutch solenoid 176 and resets
the timing mechanism. In this brief interval of time, the
temperature of the air in the plenum 12 will not be reduced to
50.degree. and, while the switch 100 is closed, the light 56 will
not be energized since the switch arm 166 has not made engagement
with the contact 220. This prevents the operator of the
air-conditioning system from obtaining an incorrect signal
concerning the operation of the motor-compressor unit.
Having described an illustrated one embodiment of this invention in
detail, it will be understood that the same is offered merely by
way of examples, and that this invention is to be limited only by
the scope of the appended claims.
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