Air conditioner outlet

A floor outlet for an air conditioner has a grill which is formed by ring elements whose radial connecting ribs are inclined to impart a vortex flow to the emerging air. A central baffle body is constituted by a disc and a multiplicity of angularly equispaced radially extending blades twisted out of the plane of the disc and projecting therefrom.

FIELD OF THE INVENTION 
This invention relates to air conditioner outlets or diffusers. 
BACKGROUND OF THE INVENTION 
It is usual when designing an air conditioner system to position the air 
outlets above the occupied space in any room, that is to say above head 
height. There is then no risk of creating unpleasant draughts and the 
incoming air is able to mix with ambient air before entering the region of 
the room which is occupied. In certain buildings, this is not possible and 
the air conditioner ducts and outlets must be floor mounted. The usually 
cool air then enters the occupied space directly from the outlets and 
there are unpleasant draught sensations and also wide variations in 
temperature between, for example, floor level and head height. 
OBJECT OF THE INVENTION 
It is an object of this invention to provide an improved air conditioner 
outlet which alleviates these problems. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention comprises an air conditioner outlet 
comprising a body adapted for floor mounting and connectable with a supply 
of conditioned air; an apertured cover capable of supporting floor loads 
and vortex generating means for generating a vortex in conditioned air 
flowing outwardly through the apertured cover. 
This generation of a vortex in the air issuing from the air conditioner 
outlet has two very important advantages. First, the air velocity of the 
incoming air is reduced much more rapidly than would be the case with a 
simple jet, thus reducing the risk of draughts. Second, the vortex effect 
provides for rapid mixing of the conditioned air with ambient air, thus 
lessening the likelihood of unpleasant temperature gradients. 
Advantageously, the vortex generating means comprises a deflector element 
positioned in the body beneath the cover. 
The deflector element can comprise a plurality of deflector blades disposed 
radially about a vertical axis. 
Preferably, the body defines an internal stabilizing chamber upstream of 
the vortex generating means. 
In any satisfactory air conditioner system, some form of temperature 
feed-back control must be provided. Often, room thermostats are mounted on 
a convenient wall to provide temperature signals which may be used to 
control either the temperature of the conditioned air or the volume of air 
at a predetermined temperature. If the building in which the air 
conditioner system is to be installed includes large open spaces with few 
fixed internal walls, there is then a difficulty as to where to position 
the room thermostats. This difficulty arises particularly with systems 
having floor mounted outlets since floor mounted outlets are ideally 
suited to large open-plan offices and the like. 
In a known arrangement, floor mounted air conditioner outlets are connected 
through underfloor ducts with a supply of conditioned air. The underfloor 
space through which the ducts pass is exhausted at a relatively low rate 
by a fan system so that a small pressure differential is maintained 
between the room and the underfloor space. Exhaust ports can then be 
provided in the floor so that stale room air is drawn into the underfloor 
space and swept away through the fan system. The present invention seeks 
to make use of this known facility in overcoming the above-mentioned 
difficulty. 
Accordingly, the present invention also comprises an air conditioner outlet 
for mounting in a floor above an exhausted underfloor space, which has a 
body connectable with a supply of conditioned air, an apertured cover 
capable of supporting floor loads, a conduit provided exteriorly of the 
body and terminating in an opening adjacent the apertured cover and 
temperature sensing means located in said conduit to provide an electrical 
indication of temperature, whereby in use the conduit communicates with 
the exhausted underfloor space with ambient air being drawn into said 
opening and across the temperature sensing means. 
Preferably, the conduit defines an internal throat portion which is of 
smaller dimension than the opening and which is disposed between the 
opening and the temperature sensing means. 
Suitably, there are provided within the body set-point means adjustable to 
set a desired temperature and comparator means providing an output 
electrical signal indicative of the difference between signals derived 
from the temperature sensor and set point means respectively. 
It has been found, contrary to expectations, that a pressure differential 
between the room and the underfloor space of as little as 10 pascals is 
sufficient to draw along the conduit enough ambient air to provide a 
sensible measure of temperature. A pressure differential which was 
significantly greater would not be acceptable in the overall design of an 
air conditioner system as it would necessitate improvements in sealing at 
floor level.

SPECIFIC DESCRIPTION 
The air conditioner outlet shown in the drawings comprises an upper ring 
part 10 and a lower plenum part 12. The outlet is installed within a 
circular floor aperture with the ring part 10 being inserted from above 
floor level and the plenum part 12 from beneath floor level, the two parts 
being secured together through axial bolt 14 so effectively sandwiching 
the floor 16 at the periphery of the aperture. 
The plenum part 12 is generally dish shaped with a peripheral flange 18 and 
a central domed portion 20 having a flat top 22 holding a captive nut 24 
for bolt 14. A shoulder 26 is formed in the domed portion 20 to enable 
closer mating with the ring part 10 as will be described. A ducting port 
28 extends radially to enable connection to be made to a supply of 
conditioned air. At a location diametrically opposite to the port 28 a 
vertical recess 30 is formed in the wall of the plenum part for a purpose 
which will be described hereinafter. 
It will be understood that conditioned air entering the plenum through port 
28 will encounter an annular chamber shown at 31 which opens upwardly. The 
plenum part thus serves to convert an incoming horizontal air jet into a 
vertical upward flow of annular cross section. 
The ring part 10 comprises a central collar 32 formed integrally through 
radial webs 34 with a coaxial, cylindrical wall 36. The upper edge of this 
cylindrical wall is formed with an integral annular flange 38. It will be 
seen that this annular flange overlies the periphery of the floor 
aperture, the floor being effectively clamped between the annular flange 
38 and the flange 18 of the plenum part. The central collar 32 has an 
integral mounting plate 40 disposed in a diametric plane; the bolt 14 
passing through an aperture in this mounting plate. 
A circular deflecting element 42 is supported on the upper peripheral edge 
of collar 32. This element takes the form of a disc 44 from which there 
extends a plurality of radial blades 46. As can be seen in FIG. 1 and in 
FIG. 3, the plane of each blade is inclined with respect to the vertical 
direction. The deflecting element is in fact produced from a single sheet 
metal disc with the blades 46 being formed by twisting a section defined 
between radial cuts. A cut out 47 is provided in each rib 34 to 
accommodate the deflecting element. 
A circular grill 48 is located in the recess defined by cylindrical wall 36 
and lies immediately on top of the deflecting element 42. The grill 
comprises a concentric series of ring elements 50, the thickness of each 
of which decreases in the vertically downward direction. The ring elements 
are supported on four equiangularly spaced ribs 52 which extend radially 
from the innermost ring element and project a short distance beyond the 
outermost ring element so as to abut the cylindrical wall 36. Each rib 52 
is of the same depth as the ring elements but is inclined (as shown in the 
phantom lines of FIG. 1) at an angle of 40.degree. to the vertical. The 
circular region defined by the innermost ring element 50 is covered by an 
integral plate 54, there being formed two circular recesses 56 in the 
upper surface of this plate concentrically with and of the same radial 
dimension as the annular inter-rib spaces. A similar recess 58 is formed 
in the flange 38 of the ring part 10, the impression thus being created 
that the annular apertures extend over substantially the entire surface of 
the outlet. 
At a location opposed to the port 28, the ring part 10 is formed with an 
integral downwardly extending conduit 60. This conduit has an opening 62 
which lies within the above described recess 58 in the flange 38, the 
major portion of the conduit having a generally rectangular cross section 
which is of the same dimension as the opening in the circumferential 
sense, but of a substantially greater dimension in the radial sense. The 
radial dimension is in fact increased by a factor of 1.75 in this 
preferred embodiment. The conduit extends to approximately the depth of 
the central collar 32 and is located within the above described recess 30 
of the plenum part. Between the opening 62 and the region of uniform cross 
section in the conduit, there is defined a throat portion 64 the minimum 
radial dimension of which is approximately one half of the radial 
dimension of the opening 62. 
Within the conduit 60, in the region of uniform cross section, there is 
provided a temperature sensor 63 mounted on an arm 66 extending radially 
inwardly to a board 68 positioned on top of the plate 40. A conical 
grommet 70 provided at the outer end of the arm 66 ensures a tight fit 
with the complementary aperture provided in the conduit. The temperature 
sensor can take a number of forms, such as a thermocouple, a thermostat or 
a semiconductor device. In whatever form, the sensor provides an 
electrical indication of temperature which is compared by suitable 
circuitry mounted on the board 68 with a set point defined by 
potentiometer 72. A resultant out of balance signal is made available 
through leads 74 to a remote control point. 
The operation of the above described air conditioner outlet can now be 
understood. In use, the outlet is connected via port 28 and other ducting 
with a variable air volume control which receives conditioned air from a 
central plant and which is capable of providing a selected volume flow of 
conditioned air to a number of similar outlets. The floor in which the 
outlets are mounted also contains a number of exhaust ports though which 
stale air is extracted under the action of a slight pressure differential 
set up between the room and the underfloor space by means of an exhaust 
fan system. This stale air is either exhausted to the atmosphere or 
returned to the air conditioning plant for recycling. 
Air entering the plenum part through the port will be redirected upwardly 
in an annular flow. It will be observed that the plenum part defines an 
internal chamber which is of annular form and which is of substantially 
smooth outline. Care is for example taken to recess the domed portion at 
shoulder 26 to receive the lower edge of the collar 32. This annular 
chamber then serves as a stabilising chamber by the use of which the 
incoming horizontal jet of air can be converted into an upward annular 
flow with low losses and, in particular, with low noise. 
The upwardly directed annular flow of air then encounters the blades 46 of 
the deflecting element. The action of these blades is to establish a 
vortex, imparting significant angular velocity to the flow. The air then 
passes outwardly between the ring elements 50, these clearly offering no 
significant resistance to the rotational motion. The supporting ribs 52 
necessarily extend transversely to the direction of rotational flow and 
might constitute an obstacle to the rotation motion. It is for this reason 
that they are inclined to the vertical as described above. The sense of 
inclination is of course the same as that of the deflector blades 46. As a 
result, the vortex generated by the deflector element persists in the air 
issuing from the outlet. This air then mixes rapidly with ambient air 
reducing in velocity and reaching rapid temperature equilibrium. 
Because of constraints imposed by the quality of sealing of the various 
floor components, the exhaust fan system is designed to produce a pressure 
drop below ambient in the underfloor space of no more than about 10 
pascals. It is found, however, that even this low pressure differential is 
sufficient to draw a significant flow of ambient air in through opening 62 
and along the conduit over temperature sensor 63. It is quite unexpected 
that this should be possible at such low pressures, particularly in such 
close proximity to an upwardly flowing vortex. The out of balance 
temperature signals that are provided by the described outlet are used to 
vary the volume of conditioned air supplied to the outlet. In a practical 
situation, perhaps only one of a number of ports supplied from the same 
variable air volume control would be provided with a temperature sensor, 
the remaining ports being then controlled effectively as slaves. 
Because the circular grill 48 and the air deflecting element 42 are simply 
dropped into position in the ring part 10, they can very easily be removed 
to enable variation of the temperature set point through potentiometer 72. 
The ability to achieve accurate temperature sensing within the floor 
mounted outlet according to this invention greatly simplifies the 
temperature control system. There is no longer any need for separate room 
thermostats wired individually to the control centre. It will be 
appreciated that the electrical connection of a temperature sensor in the 
described outlet to the variable air volume control is very simple, 
following as it does the line of the air ducting. 
This invention has been described by way of example only and a variety of 
modifications are possible without departing from the scope of the 
invention. For example, it would be possible to employ different forms of 
vortex generator other than the described deflector. Vanes or baffles 
could be provided in either the ring part or the plenum part although it 
is preferred that the plenum part should define a stabilising chamber 
upstream of the vortex generator enabling an upward flow to be established 
at relatively low noise levels before the vortex generator is encountered. 
The manufacture of the deflector element from a single piece of sheet 
metal has the merit of simplicity but other methods of construction are 
possible; for example plastics moulding. The use of a deflector element 
which is separate from the grill is felt to be particularly advantageous. 
As will be evident, the grill must be capable of supporting floor loads 
and this imposes significant design constraints. The design of the 
separate air deflector can however be dedicated to the function of 
generating a vortex, enabling optimum aerodynamic performance to be 
achieved. 
It will be apparent that in certain applications--for example where the 
outlets are to operate as slaves--it is not essential for a temperature 
sensor to be provided. The conduit can then, optionally, be omitted. 
In certain particular situations where--for example--outlets are 
distributed around the perimeter of a high-ceiling room, it may be 
advantageous to omit the vortex generator. Since the described air 
deflector is simply dropped into position this can be achieved without 
structural modification. The described benefits of the temperature sensor 
will still be achieved. 
It will be apparent to the skilled man that the body of the outlet can be 
produced in forms other than the described two-part form although this is 
felt to be particularly attractive enabling both assembly and mounting of 
the outlet to be achieved by the use of a single bolt. In applications 
where strict fire standards are set, the major components of the outlet, 
with the possible exception of the air deflector element which is 
enclosed, would be produced of metal. In other applications, materials 
such as plastics could be employed. 
By the use of blanking rings engaged in one or more of the grill annular 
slots, an outlet designed for one particular flow rate can operate with 
substantially the same performance characteristic at reduced flow rates. 
This leads to considerable economies in manufacture.