US3332475A

US3332475A - Air-conditioning control system

Info

Publication number: US3332475A
Application number: US483931A
Authority: US
Inventors: Dale L Selhost; James P Warner
Original assignee: American Air Filter Co Inc
Current assignee: American Air Filter Co Inc
Priority date: 1965-08-31
Filing date: 1965-08-31
Publication date: 1967-07-25
Anticipated expiration: 1984-07-25
Also published as: DE1604125C3; DE1604125B2; GB1162207A; DE1604125A1

Abstract

1,162,207. Cams. AMERICAN AIR FILTER CO. Inc. 22 Aug., 1966 [31 Aug., 1965], No. 37614/66. Heading F2K. [Also in Division F4] An adjustable profile cam employed in an air conditioning unit (see Division F4) comprises two plates 53a, 55 linked by a spring 62. On counter-clockwise rotation of the cam, the follower 57a follows the profile shown, but on clockwise rotation the follower abuts against the surface 70a of plate 55, and moves this relative to plate 53a against the spring 62 until a screw 67 on the plate 53a abuts against a projection 66 on the plate 55.

Description

July 25, 1%? n. L. SELHOST ETAL 3,332,475

AIR-CONDITIONING CONTROL SYSTEM Filed Aug. 31, 1965 2 Sheets-Sheet 1 INVENTORS 047/2 Ade/host James War/72f y 1957 D. L. SELHOST ETAL 3,332,475

AIR-CONDITIONING CONTROL SYSTEM Filed Aug. 31, 1965 2 Sheets-Sheet 2 INVENTORS a/@ L. Se/hosz James 2 Warner United States Patent 3,332,475 AIR-CONDITIONING CONTROL SYSTEM Dale L. Selhost, Rock Island, Ill., and James P. Warner, Bettendorf, Iowa, assignors to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaare Filed Aug. 31, 1965, Ser. No. 483,931 9 Claims. (Cl. 165-16) ABSTRACT OF THE DISCLOSURE A ventilator arrangement for conditioning a selected space where damper means are provided to regulate quantities of outdoor air and room air supplied to the ventilator in response to the temperature in the selected space and the tempering medium supplied to air heating means and air cooling means included in the ventilator is controlled in response to the position of the damper means.

Background of the invention Unit ventilators, as known in the art, provide for mechanically cooling and heating air for a given space to be served and also provide for the use of outdoor air to ventilate and cool the space to be served through the introduction of outdoor air in amounts up to one hundred percent of rated capacity. Where the introduction of outdoor air is not sufficient to provide the cooling required to maintain the temperature of the served space, mechanical cooling is used. In previously manufactured unit ventilators, the cooling medium is continuously furnished to the cooling coil from a central source remote from the individual unit. Air flow is diverted away from the cooling coil of the individual unit ventilator when the unit is in the natural ventilation or heating cycles. Operation of such unit ventilator has in many instances been inefiicient as a result of the heat gained by the cooling rnediiun in circulating through the unit when the unit is in a heating cycle, and cooling is not needed, and there has been further waste resulting from the refrigeration capacity lost through this heat gained by the cooling medium. Inordinate condensation of Water on the cooling coil occurs as the result of circulation of cooling medium through the cooling coil when the unit is not in the cooling cycle, air cooling is not needed and air is not passing over the cooling coil. The condensation leads to freezing of the coil and corrosion of the interior of the cabinet.

In previously manufactured unit ventilators, in instances when both heating and cooling tempering mediums have been employed in the same unit, a single control mechanism capable of acting in opposed directions has been utilized to selectively increase or decrease the tempering effect of a preselected medium in accordance with the directional movement of such control mechanism. Additional selector apparatus has been required to select the medium to be modulated by the single control mechanism.

Summary of the invention In accordance with the present invention, a novel, independent straightforward, economical to construct and maintain, synchronous, and readily responsive unit ventilator is provided which selectively supplies cooling medium to the cooling coil of a unit ventilator in accordance with the position of air directing dampers or damper controllers in the unit. Further, the present invention provides a unit ventilator which controls both mediums in a unified system by means of a controller which moves in one direction for increasing the intensity of one tempering medium, and in another direction for increasing the "ice intensity of the other tempering medium, thus eliminating the heretofore required expensive and cumbersome medium selector mechanism.

Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth hereinafter.

More particularly, the present invention provides a room air-conditioning unit comprising: a unit housing, an air inlet means, an air discharge outlet means, means for inducing flow of air through the unit housing, air damper means for controlling the flow of air through the unit; air tempering means in the housing selectively operated in accordance with preselected positions of the air dampers.

It is to be understood that various changes can be made in the arrangement, form and construction of the apparatus disclosed herein without departing from the scope or spirit of the present invention.

Referring to the drawings which disclose an advantageous embodiment of the present invention:

FIGURE 1 is an exploded schematic view of the operating parts of the unit ventilator;

FIGURE 2 is a vertical section view taken along a plane passing through line 22 of FIGURE 3;

FIGURE 3 is a perspective view illustrating a selfcontained air-conditioning unit ventilator in a typical location along an outside wall of a room below a window; and

FIGURE 4 is a drawing of a sequence cam of the type used to initiate and terminate compressor operation.

In one embodiment of the present invention, as seen in FIGURE 1, the unit ventilator comprises an air tempering section including an air heating coil 1 to selectively heat air passing through the unit and an air cooling coil 2 to selectively cool air passing through the unit. In the present embodiment a refrigerant compressor 60 and refrigerant condenser 6 furnish refrigerant to the cooling coil 2. The elements of the air tempering section are operated by power-driven cam actuating mechanism 36 which moves in response to the temperature in the space to be served, as sensed by thermal element 35, and controls the operation of the elements of the tempering section in accordance with the position of

air dampers

16, 17, 18, 19, hereinafter described. Room air damper 16, minimum air damper 17, outdoor air damper 18, and bypass damper 19 are operated in response to the operation of cam actuating mechanism 36 as transmitted by cam 37 and the intermediate damper operating linkages hereinafter described in detail. Room air damper 16 controls the amount of air recirculated to the unit from the space served by the unit and outdoor air damper 18 controls the quantity of outdoor air admitted to the unit.

Dampers

16 and 18 are moved in opposite relative directions by linkage means hereinafter described in detail. Bypass air damper 19 moves from position fully blocking off the heating coil 1 from inlet air flow when compressor 60 is in operation to position fully blocking off cooling coil 2 from inlet air flow during selected periods hereinafter described, and in intermediate position controls the proportion of air passing through each coil. Minimum air damper 17 is open during compressor operation, when outdoor air damper 18 is closed, to provide a minimum amount of fresh air to the served space.

More particularly, as may be seen in FIGURE 1, powerdriven damper cam actuating mechanism 36 turns damper cam 37 in response to variation in temperature sensed by thermal element 35 located in the space to be served. Damper cam 37 includes

slotted track

38 and 39 in its face to receive cam follower 25 which drives minimum air damper 1'7 and bypass damper 19, and cam follower 26 which drives room air damper 16 and outdoor air damper 18. The cam followers move freely in

tracks

38 and 39, respectively, in response to the movement of cam 37.

Cam follower which transmits the motion of cam 37 to bypass damper 19 and minimum air damper 17 by linkage hereinafter described is nested to move in track 38 in response to movement of cam 37 and is also afiixed to lever 32 pivotally joined to partition 47 by means of pivot pin 30. Minimum air damper linkage 29 is attached to one end of pivoted lever 32 and the opposite end of linkage 29 is fastened to lever 49 to turn minimum air damper operating shaft 17a. Bypass damper linkage 33 is attached to lever 32 at one end and to bypass damper crank 34 at the other end. Bypass damper crank 34 is attached to bypass damper operating shaft 19a to move shaft 19a in response to movement of cam 37 through the linkage hereinbefore described. The minimum air damper 16 and bypass damper 19 are moved by an amount dependent upon the configuration of the aforementioned linking mechanisms associated with lever 32.

The rotary motion of cam actuating mechanism 36 is transmitted to damper cam 37 and cam follower 26 moves in slot 39 of damper cam 37. The motion of follower 26 is transmitted to outdoor air damper shaft 18a by crank 41. The motion of outdoor air damper shaft 18a is further transmitted by means of crank 40 to crossed

links

27 and 28 and arcuate lever 46, thence to room air damper shaft 16a to move room air damper 16 in inverse relation to the movement of outdoor air damper 18. Crank 40 is attached at one end to shaft 18a and at points along crank 40 crossed

links

27 and 28 are slidably afi'ixed by pin means 42 and 43 extending through slots 44 and 45, respectively, in

links

27 and 28. Crossed

links

27 and 28 are pivotally affixed to arcuate lever 46 which is attached to room air damper operating shaft 16a. When outdoor air damper 18, hereinafore described, is open, slots 44 and allow room air damper 16, hereinafore described, to retain a degree of rotational freedom, dependent upon the relative length of slots 47 and 48, so that a gust of outdoor air entering the ventilator will close room air damper 16 and prevent the outdoor air from flowing through the room air damper and directly into the space served by the ventilator.

Sequence switch cams 53 are provided to operate sequence switches 54 which control various parts of the unit hereinafter described. Sequence switch linkage 50 is pivotally aflixed to damper cam 37 by pivot 48 and to suitably journaled cam shaft 52 by lever 51. Cams 53 of desired configuration are mounted in spaced relation on shaft 52 to cooperatively engage sequence switches 54 by means of cam followers on switches such as, for example, follower 57 of switch 54a, to open or close switches 54 in preselected positions of

dampers

16, 17, 18 and 19, which, as aforestated, are moved through proper linkage by cam 37 and cam actuating mechanism 36. Switches 54 can be adapted to operate any of a number of services to the unit, although only two such services are discussed hereinafter. It will be understood that switch linkage 50 can, within the scope of this invention, be operated by any convenient portion of the damper control system, and further, that in a synchronous air-conditioning control system as herein disclosed, any convenient means may be used to operate the switches of the control system in accordance with selected positions of the air-directing elements.

Refrigeration compressor 60 is part of the self-contained refrigeration system of the unit ventilator which can include, in addition to compressor 60, refrigerant evaporator 2 and refrigerant condenser 6. Pursuant to the present invention, refrigeration compressor 60 can be operated when sequence switch 54a closes power circuit 61 in response to movement of air dampers and cams 37 and 53a to preselected position. A self-contained, mechanical refrigeration system is used in this advantageous embodiment of the present invention to provide cooled refrigerant as the cooling medium for the air cooling means but it will be understood that the invention herein disclosed is suitably applicable to air-conditioning units providing synchronous operation between the supply of cooling medium to the unit and the position of air dampers in the unit, regardless of the manner of furnishing the cooling medium.

In accordance with another feature of the present invention, to prevent frequent off-on operation of compressor 60 when maintenance of served space temperature requires very little mechanical cooling, an arrangement is provided to terminate compressor operation at lower preselected served space temperatures than those at which compressor operation is commenced. This advantageous feature can be accomplished, as seen in FIGURE 4 and hereinafter described, by providing compressor actuating cam 53a with a second cam of advantageous configuration. Cam 53a turns, in periods of rising served space temperature, to cause switch 54a to close and initiate operation of compressor at preselected served space temperatures in accordance with preselected positions of the aforementioned air dampers. Second cam 55 is mounted on shaft 52 in adjacent relation to cam 53a and is independently rotatable on shaft 52. The combination of

cams

53a and 55 will be seen to include a second cam return spring 62 attached to post 63 on second cam 55 and post 64 on cam 53a, an upturned tab 65 attached to cam 53a which includes thread means to receive an adjustable threaded member 67 and a cooperating upturned stop 66 on second cam 55 to be struck by the end of threaded member 67 and when cam 55 is rotated in a counterclockwise direction relative to cam 53a. It will also be noted that earn 53a has a smaller diameter surface 69 and a larger diameter surface 68, cam 55 has a larger diameter surface generally corresponding to the larger diameter surface 68 of cam 53a, and the inner and outer diameter surfaces are cooperatively aligned with follower 57 of sequence switch 54a to permit followers 57 to travel on the turning cams. Although the two-part cam can operate in any desired manner, the method of operation in the advantageous embodiment disclosed herein is as follows: When the unit is in heating or natural ventilation cycles and the compressor is not operating, the cam is in a position where the follower 57 of sequence switch 54a travels on the outer diameter 68 of cam 53a. Spring 62 holds second cam 55 in the position shown in FIGURE 4. As the temperature in the space served by the air conditioner increases and mechanical cooling is required, cam 53a rotates in a counterclockwise direction. Follower 57 travels on outer surface 70 of cam 66 and outer surface 68 of cam 53a until it reaches point 70a of diameter 70. It then moves to cam surface 69 of cam 53a and closes switch 54a to initiate compressor operation which continues so long as follower 57 travels on surface 69. For rising served space temperature, cam 53a turns in a clockwise direction. As follower 57 of switch 54a contacts second cam 55, the second cam moves with follower 57 in opposition to the tension of spring 62 until the end of threaded member 67 contacts upstruck tab 66 of second cam 55 to stop the relative motion of second cam 55 with respect to cam 53a. Follower 57 of switch 54a then travels to outer surface 70 of cam 55 to open switch 54a and terminate compressor operation at a lower served space temperature than where compressor operation was initiated. It can be seen that the difference in served space temperature between the point of initiation and the point of stopping compressor operation is determined by the length of the surface 70 of cam 55 and the adjustment of threaded member 67.

FIGURE 3 shows a typical unit ventilator installed below a window of a room to be served. The exterior cabinet of the unit is formed of a number of panels including: a main top wall panel 12 having a conditioned air outlet grille 5 along its front; a control access panel 14 at the right end of the unit overlying the control and compressor compartment which houses the ventilator control mechanisms and cooling equipment previously described in detail. A main front wall 12a which covers a central compartment of the unit includes a lower front access panel 13 of louvered character to admit room air into the unit for recirculation. A control and compressor compartment access front panel 15 is provided at the right end of the unit and end panels 12b to cover the respective ends of the unit.

The assembled arrangement of the air conditioning and air moving elements can be seen in schematic form in FIGURE 2 which is a view taken in a plane passing through line 22 of FIGURE 3. The outdoor air inlet 9 to the unit and the condenser air outlet 7 extend through the room wall and are exposed to the outside of the building. Outdoor air fan 10 can operate as a result of the position of one of the cams 53, closing a switch 54 at preselected damper position, but whatever the manner of operation of the fan control, the fans operate in conjunction with the refrigeration compressor to provide cooling air to the refrigerant condenser 6. Condenser air passes through the chamber formed by fan housing and generally vertical panel 21 and to condenser 6. Outdoor air is admitted to the air-conditioning portion of the unit through outdoor air damper 18 which is shown in closed position in FIGURE 2. Room air recirculated to the unit enters through room air inlet 13 and the flow is controlled by room air damper 16, shown in the figure in open position. Room air and outside air are mixed in the common passageway formed between the dampers and the mixed air passage through air filter 11. Longitudinally-extending heating coil 1 to receive heating medium, and cooling coil 2 to receive cooling medium, arranged in an inverted V configuration, are provided to thermally condition air passing through the unit. Bypass damper 19 is provided to divert the flow of air to either coil as desired. A minimum outdoor air passageway 8 and a minimum outdoor air damper 17 are provided to furnish fresh air to mix with recirculated air during the mechanical cooling cycle, when outdoor air damper 18 is closed and refrigeration compressor 60 is operating. Longitudinally-extending

air dampers

16, 17, 18 and 19 extend substantially the length of the air-conditioning unit and each damper is mounted on its

particular shaft

16a, 17a, 18a and 190, respectively. Each shaft extends through the control compartment, is journaled at one end of the cabinet and extends through suitable bearings in the partition 47 at the other end of the central compartment to join the damper control linkage aforedescribed. Conditioned air passing through heating coil 1 and/ or evaporator 2 is drawn into the room air fan 12 and blown through grille 5 into the space to be served.

Reference is now made to the drawings for a description of the operation of the unit. During a morning warmup when room air or served space temperature is low, air dampers responsive to cam 37 are in preselected position so that switch 54b is closed by cam 53a and circuit 56 causes desired heating medium to be supplied to heating coil 1. In this advantageous embodiment electric heat is provided as an example; however, it is to be understood other appropriate heating systems can be used as desired. Outdoor air damper 18 is closed to prevent the admission of additional cool, outside air. Bypass damper 19 is in position blocking off evaporator 2 so that room air is circulated only through the heating coil 1. Cam 37 is turned by cam actuating device 36 in response to changing room temperature, and when a preselected room temperature has been attained, cam 37 has been turned to a preselected position so outdoor air damper 18 begins to open as a result of the movement of follower 26 in track 38. Outdoor air damper 18 continues to open in response to movement of cam 37 until it reaches a preselected minimum outdoor air opening, where it remains until the served space temperature increases to a point where heating medium is no longer supplied to heating coil 1, hereinafter described. Room air damper 16 and outdoor air damper 18 are linked by shaft 18a, crossed

links

25 and 26, and arcuate lever 46 to move in opposite directions so that as outdoor air damper 18 opens, room air damper 16 closes proportionately. Upon additional increase in served space temperature, bypass damper 19 is moved by cam 37 from position blocking evaporator 2 to a position further and further toward heating coil 1 in response to increasing served space temperature. Movement of bypass damper away from evaporator coil 2 toward heating coil 1 modulates the temperature of conditioned air leaving the unit by reducing the proportion of air pasing through heating coil 1. Cam 37 continues to move cam 53b for rising served space temperature and at preselected position causes sequence switch 54b in circuit 56, which controls the supply of electricity to heating coil 1, to open, thus cutting off the supply of electricity to coil 1. It will be realized the supply of heating medium to coil 1 can be stopped completely at preselected position of cam 37 corresponding to a preselected served space temperature, or the supply of heating medium to coil 1 can be decreased in any desired fashion by the use of proper controls. When the supply of heating medium to heating coil 1 has ceased and bypass dam-per 19 has been moved to a position blocking heating coil 1, the unit enters natural cooling cycle for further increase in served space temperature. In the natural cooling cycle, outdoor air damper 18 is opened progressively from the minimum outdoor air position, in response to further movement of cam 37. Cam 37 moves in the same direction during the entire period of rising served space temperature and reverses direction only for decreasing served space temperature. When outdoor air damper 18 is fully opened, cam 37 moves further in the same direction for an additional increase in served space temperature and the outdoor air damper 18 closes. The unit then enters the mechanical refrigeration cycle. In the mechanical refrigeration cycle, compressor operation is initiated by movement of cam 37 in accordance with preselected position of outdoor air damper 1S and bypass damper 19. As cam 37 is moved by cam actuating means 36, cam 53a closes sequence switch 54a to actuate circuit 61 in response thereto, which initiates compressor operation to supply cooling medium, expanding refrigerant in this case to cooling coil 2. Minimum air damper 17 is opened by movement of cam 37, to provide fresh air to the space to be served during the cooling cycle. To prevent oif-on cycling of the refrigeration system, compressor operation is terminated at served space temperature lower than the temperature at which compressor operation is initiated and is accomplished by the method hereinbefore described through

cams

55 and 53a.

For operation during periods of falling served space temperature, cam actuating device 36 turns damper cam 37 in the opposite direction to operate dampers 16, 1'7, 18 and 19, refrigeration circuit 61, and heating circuit 56 in reverse order from that hereinbefore described.

Cam actuating device 36 can be spring loaded so that when the served space is unoccupied, the unit can be selectively turned to a so-called night cycle. In this position, cam actuating device 36 is turned past the full heat position by the spring to a position where no heating medium can be supplied to the coil. Room air damper 16 is then open, outdoor air damper 18 is closed, and bypass damper 19 is fully blocking cooling coil 2. In this position, the cam actuating device is in a full heat position but heating medium cannot be supplied to the heating coil 1 and a further decrease in served space temperature below the desired minimum cannot operate the cam actuating device because it is at rest in the full heat position. To maintain a minimum desired temperature in the served space, it is therefore necessary to provide supplemental means for supplying heating medium to heating coil 1. To accomplish this, means (not shown) are provided whereby, during the time the unit is in night cycle,

the cam actuating device 36 will reverse itself and move to a position to supply heating medium to the heating coil 1 in response to preselected minimum served space temperature, but will not go through the normal cycles herein described. When the preselected minimum served space temperature is reached, the supply of heating medium to the coil is cut oil.

Analysis of the operation of the unit ventilator herein described clearly illustrates that among other advanta geous aspects of the synchronous control system, the cam actuating mechanism assures air dampers are in prescribed positions before tempering medium is supplied to the unit.

The invention claimed is:

1. An improved air-conditioning unit comprising a unit housing having air inlet means including an outdoor air inlet and a room air inlet, an air discharge outlet to emit air from said housing to a space to be served by said air conditioning unit, means for providing flow of air through said housing from said air inlet means to said air discharge outlet, damper means for controlling the proportions of out door air and room air admitted to said unit; temperature sensing means in said space, cam actuating means to move in only one direction in response to increase in temperature in said space to be served by said unit, and in a second direction in response to decrease in temperature in said space to be served, so said damper means selectively controls relative flow rate of outdoor air and room air introduced to said unit in response to change in temperature in said space to be served; air heating means; air cooling means; and, means to selectively supply tempering medium to said air cooling means and said air heating means in accordance with the position of said damper means.

2. The apparatus of claim 1 wherein said cooling means comprises mechanical refrigeration means including compressor means, evaporator means, and condenser means.

3. An improved air-conditioning unit comprising a unit housing having air inlet means including an outdoor air inlet and a room air inlet, an air discharge outlet to emit air from said housing to a space to be served by said air conditioning unit, means for providing flow of air through said housing from said air inlet means to said air discharge outlet; first damper means including a room air damper and outdoor air damper for controlling the proportions of outdoor air and room air admitted to said unit; a passageway in said housing communicating with said room air inlet, said outdoor air inlet, and said air discharge outlet, said passageway including therein cooperatively disposed air heating means, air cooling means, and second damper means including bypass damper means operable between one extreme position to block off air flow through said air heating means and an opposite extreme position to block off air flow through said air cooling means; temperature sensing means in said space, damper actuating means to move said first and second damper means in response to air temperature in space served by said air conditioning unit; means to selectively supply heating medium to said air heating means in accord ance with preselected position of said damper means and means to selectively supply cooling medium to said air cooling means in accordance with preselected position of said damper means.

4. The air-conditioning unit of claim 3 wherein said cooling medium is supplied to said air cooling means when said bypass damper is in position blocking off said air heating means and said outdoor air damper is in position blocking oif said outdoor air inlet.

5. The room air-conditioning unit of claim 3 and cam actuating means to move in one direction for increase in temperature in said space served by said room air conditioner and in another direction in response to increase in temperature in said space served by said air conditioner to move said first damper means to selectively control the relative flow rate of outdoor air and room air introduced into said conditioning unit in response to change in temperature in said space to be served and move said second damper means between said one extreme position and said other extreme position to selectively control air flow through said air heating means and said air cooling means.

6. The room air-conditioning unit of claim 5 wherein said cooling medium is supplied to said cooling means until said temperature in said space served by said airconditioning unit has decreased to a second preselected temperature where said second temperature is less than the temperature at which said supply of cooling medium was initiated to said cooling means in accordance with position of said damper means.

7. The room air-conditioning unit of claim 5 wherein said heating medium is supplied to said air heating means and said cooling medium is supplied to said cooling means in accordance with preselected position of said actuating means.

8. An improved air-conditioning unit comprising a unit housing having an outdoor air inlet, a room air inlet, an air discharge outlet, means for inducing flow of air through said housing; damper means including an air bypass damper, and a room air damper and outdoor air damper for controlling the proportion of outdoor air and room air admitted to said unit, a passageway in said housing communicating with said room air inlet, said outdoor air inlet, and said air discharge outlet, said passageway including therein air heating means, air cooling means, and said bypass damper, said bypass damper being operable between a first extreme position to block oii air flow through said air heating means and a second extreme position to block off air flow through said cooling means; temperature sensing means in said space, actuating means to move said damper means in response to air temperature in the space to be served by said air-conditioning unit wherein said actuating means moves in one direction for rising temperatures in space served by said room air conditioner and moves in another direction for decreasing temperatures in the space served by said air conditioner to move said outdoor air damper and said room air damper to selectively control relative quantity of outdoor air and room air admitted to said unit, move said bypass damper from one said extreme position to said other position in response to change in temperature in said served space, selectively supply heating medium to said air heating means in accordance with preselected position of said damper means and to selectively supply cooling medium to said air cooling means in accordance with preselected position of said damper means wherein said cooling medium is supplied to said air cooling means when said bypass damper is in position blocking off said air heating means, and said outdoor air damper is in position blocking off said outdoor air inlet; and said cooling medium is supplied to sad cooling means until said temperature in said space served by said air-conditioning unit has decreased to a second preselected temperature where said second temperature is less than the temperature at which said supply of cooling medium was initiated to said cooling means.

9. An improved air-conditioning unit comprising a unit housing having air inlet means including an outdoor air inlet and a room air inlet; an air discharge outlet to emit air from said housing to space to be served by said airconditioning unit; means for providing flow of air through said housing from said air inlet means to said air discharge outlet; air heating means; air cooling means; temperature sensing means in said space, damper means including first damper means for controlling the proportion of outdoor air and room air admitted to said unit in response to temperature in said space served by said unit and second damper means for directing selected quantities of air to said air heating means and said air cooling means in response to temperature in said space served by sai unit; and, means to selectively supply tempering medium to said cooling means and said air heating means in accordance with the position of said damper means.

References Cited UNITED STATES PATENTS 10 Baker et a1. 16516 Davis et a1. 16516 X Schemenauer 16516 X Bryans et a1. 165-22 X ROBERT A. OLEARY, Primary Examiner.

MEYER PERLIN, Examiner.

M. A. ANTONAKAS, Assistant Examiner.

Claims

9. AN IMPROVED AIR-CONDITIONING UNIT COMPRISING A UNIT HOUSING HAVING AIR INLET MEANS INCLUDING AN OUTDOOR AIR INLET AND A ROOM AIR INLET; AN AIR DISCHARGE OUTLET TO EMIT AIR FROM SAID HOUSING TO SPACE TO BE SERVED BY SAID AIRCONDITIONING UNIT; MEANS FOR PROVIDING FLOW OF AIR THROUGH SAID HOUSING FROM SAID AIR INLET MEANS TO SAID AIR DISCHARGE OUTLET; AIR HEATING MEANS; AIR COOLING MEANS; TEMPERATURE SENSING MEANS IN SAID SPACE, DAMPER MEANS INCLUDING FIRST DAMPER MEANS FOR CONTROLLING THE PROPORTION OF OUTDOOR AIR AND ROOM AIR ADMITTED TO SAID UNIT IN RESPONSE TO TEMPERATURE IN SPACE SERVED BY SAID UNIT IN AND SECOND DAMPER MEANS FOR DIRECTING SELECTED QUANTITIES OF AIR TO SAID AIR HEATING MEANS AND SAID AIR COOLING MEANS IN RESPONSE TO TEMPERATURE IN SAID SPACE SERVED BY SAID UNIT; AND, MEANS TO SELECTIVELY SUPPLY TEMPERING MEDIUM TO SAID COOLING MEANS AND SAID AIR HEATING MEANS IN ACCORDANCE WITH THE POSITION OF SAID DAMPER MEANS.