US1994441A

US1994441A - Control mechanism

Info

Publication number: US1994441A
Application number: US711324A
Authority: US
Inventors: Lewis R Smith; William A Minkler
Original assignee: Westinghouse Electric Corp
Current assignee: Westinghouse Electric Corp
Priority date: 1934-02-15
Filing date: 1934-02-15
Publication date: 1935-03-12
Anticipated expiration: 1952-03-12

Description

Patented Mar.. i2, 1935 iran stares MMAI est

CUNTROL MEC ti 2 Application February l5, 1934i, Serial No. 711,324

' c om; (el. 23e- 44) Our invention relates to a control system for l air conditioning apparatus and it has for its object to provide an improved system.

A further object of our invention is to provide a control system, for a plurality of air treating devices receiving an air treating medium from a common source, which operates so that the number of. devices which are connected to said source is always in excess of a predetermined number. l

While not necessarily limited thereto, our invention is particularly adapted to control relatively small air conditioning devices commonly referred to as room conditioners. These de-f vices usually include an evaporator or cooling coil for cooling air, a humidifying deviceand a fan for translating air to be treated. These elements are usually carried by a casing and form a unitary structure.

It is frequently desirable to operate a number of these devices for cooling air from a single refrigerating machine and, therefore, the number of devices that are connected to it at one time should be maintained above a predetermined minimum for eiiicient operation and to prevent frosting of the evaporator by reason of reduced temperature.

According to our invention, we provide a pluralityof air cooling devices which are operated in groups. A switch is provided for controlling the operation of the refrigerating machine and the flow of refrigerant to all devices in a group, one such switch being preferably provided for each cooling device. A second switch is provided for each device for control of the fans, and all of the fan switches in a group are so interconnected that all of the fans in the group may be controlled from any switch. In order that circulation of air is assured at all times that cooling is effected, we prefer to interconnect the first and secondmenticned switches so that the former are euergized only when at least one ci the latter are closed to operate the fans. A

When the room conditioners are provided with humid'lfying means, they may be operated in the same manner as when cooling; that is, when a switch is closed to eect humidication, all fans' and humidifying devices in the group operate to circulate and humidify theair.- Means are preferably provided wherebythe fans of a group` may be operated for ventilation without the cooling or humidifying. means being operative. If desired, automatic control of a group of devices in accordance with conditions of the air in the space served thereby may be effected by providing suitable instruments, such as, thermostats or humidostats, in the space and connecting the same-in the electrical circuits of the group of devices.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in accordance with the accompanying drawing, forming a'. part of this application, in which: n Fig. 1 diagrammatically shows a plurality of air conditioning devices having our improved control system applied thereto.

Fig. 2 is a straight line or schematic diagram of the control system.

The air conditioning devices are preferably Y operated in groups, which may respectively serve a plurality of spaces, one of which is generally` shown at 10. We have shown but one group of devices as the other groups are identical with the one shown; however, the circuits leading to the other groups are indicated in the drawing. The group indicated at Vincludes rst and second air conditioning devices 11 and 12, each of which includes an evaporator orair cooler 13, a humidiying device 14 and afan 15 for translating. air to be treated. These elements are disposed withina cabinet structure 16 which has an inlet opening 17 through which air to be treatinet 16 for treatment and then discharging itto the space 10 through the opening 18.

It will be seen that we have shown the openings 17 of both devices 11 and 12 .in communication with the space 10 so that the air therein is recirculated but it will be understood that fresh air from the outside atmosphere may be treated in which case the inlet openings 17 would communicate with the exterior of the building. The fans are preferably driven by electric motors 19. The humidifying devices 14 are supplied with Water from a pipe 21 which connects to a suit able source. Valves 22 are connected in the pipe 21 for controlling the ow of water to thefhumidifying devices 14 and are .preferably operated by solenoids 23. The humidifyng devices 14 inl clude nozzles 24 through which water is discharged in a-,nely divided condition or mist into the air propelled by the fan. The body 0`f airl passing through the mist readily vaporizes and absorbs moisture therefromf Water discharged by the nozzle 24 which is not vaporized and taken 11p bythe air falls to the bottom of the cabinet at'A 16 and is drained away through a conduit 25 to a point of discharge. It will be understood that, during winter operation, the air in the space 10 isheated either by some extraneous means or by heaters 26 disposed within the cabinets 16.

-The heaters 26 are of conventional construction and are supplied with a heating medium in any well known manner.

The air coolers or evaporators 13 are supplied with refrigerant for absorbing heat from the air to be treated by a refrigerating machine 27. The latter may be of any suitable type but we prefer and show a machine of the compressor-expander type which includes acompressor 28, driven by a motor 29, and a condenser 31. The evaporators 13 include expansion devices, preferably valves 32, for effecting a reduction in pressure of the refrigerant supplied to the evaporators 13. these valves 32 are of well known construction, no further description of them is deemed necessary.

The cooling system operates on the well known compression-expansion cycle in which' gaseous or spent refrigerant is withdrawn from the evaporators 13 by the compressor 28 through a branched conduit 33. It is then compressed by the compressor 28 to a relatively high pressure and is discharged into the condenser 31 in which `it is cooled and condensed. The liquid refrigerant is then conveyed by a conduit 34 to the expansion valves 32 which reduces thepressure of the refrigerant to that maintained in the-evaporator by the suction of the compressor. When subjected to the relatively low pressure in the evaporators 13, the refrigerant vaporizes and abstracts heat from the evaporator in a well known manner. Air which is conveyed in heat-exchanging relation with the cold evaporator 13 is cooled therein before it is delivered to the space 10. The iow of 'refrigerant to the evaporators 13 may be controlled, preferably by a valve 35, `connected in the conduit 34, and operated by a. solenoid 36.

The conduit 34 is provided with branches 34a and 34h, having valves 35a and 35h, respectively, for supplying liquid refrigerant lto additional groups of air conditioning devices which are identical with the devices 11 and 12,` and the conduit 33 is provided with branches 33a and 33b for withdrawing vaporized refrigerant therefrom.

The various groups of air conditioning devices are supplied with current from a source of current (not shown) through conductor Ll and L2 and

circuits

37, 38, and 39. The

circuits

38 and 39 run to said additional groups of air conditioning devices and are identical with the circuit 37; therefore the complete circuit diagram for these circuits is not shown. The

circuits

37, 38, .and 39 supply relatively low voltage current for the operation of the various fan'motors 19 and for the control circuits. The motor 29 however is preferably supplied with higher voltage current through conductors 41 in which contacts 42 of' a relay 43 are connected. The latter also includes a solenoid 44 for operating the contacts 42.

Reference will now be had to the control circuits shown in connection with the air conditioning devices 11 and 12. The air conditioning device 11 has a plurality of

switches

45, 46,

and 47 associated therewith and the device 12 includes

similar switches

48, 49, and 51. `These switches are mounted adjacent toy their respective devices and are preferably carried by the cabinets 16 thereof. The switches l45 and 48 control the supply of refrigerant to the evaporators'13and the operation of the refrigeratin A described.

machine 27. The

switches

46 and 49 control the operation of the humidifying devices 14 and the fans 15. Switches 47 and 51 control the operation of the fans 15.

If automatic control of the temperature of the air in space 10 to be eiected,`is a thermostat 52 is disposed in the space 10. The thermostat 52 operates switches 53 and 54 which respectively control the operation of the valve 35 and the relay 43. The humidity of the air in space 10 may be controlled by a humidostat 55 which includes a switch 56 connected in circuit with the solenoids 23. The thermostat 52 maintains its switches 53 and 54 open when the temperature of the air in' the space 10 is below a predetermined degree and the humidostat 55 maintains its switch 56 open when the humidity of the air is above a predetermined amount. As these instruments are well known in the art, no further description of them will be given. n

The conductors which connect the various control elements are clearly shown in the drawing and will be referredto in the description of operation which follows. For winter operation, one of the

switches

46 or 49 will be closed to render the fans 15 and the humidifyingv devices`14 operative. The circuit for the fans may be traced from line conductor L1, conductor 57 of circuit 37, one poleof switches 46 or 49, conductor 58, fans- 19 of the devices 11 .and 12, conductor 59 of circuit 37 to the line conductor L2. 'I'he circuit forthe solenoids 23 which control valves 22 in the water supply line 21 may be traced from line conductor L1, conducy tor 57, the other pole of

switches

46 or 49, conductor 61, switch-56 of the humidostat 55, conductor 62, solenoids 23, conductor 59, ,to the other line conductor L2.

It will be understood, that, during winter operation, the air in the space 10 will be heated, for example, by the heaters 18. If the humidity of the air is below a predetermined amount, the humidostat switch 56 is in its closed position. Therefore,

current iiows through the circuit described above which includes the solenoids 23. The va1ves`2?-r are maintained open thereby so that water from the supply pipe 21 flows to the humidifying devices 14 and is sprayed bythe nozzles 24 into the air being translated by the fans 1'5. Moistened air delivered to the space'10 increases its humidity; and, when a predetermined amount is attained,the humidostat 55 opens its switch 56 for deenergizing the solenoids 23. 'I'he valves'22 are l 58 and parallel the. pole of switch 46, and of switch 49, which is included in the fan circuit previously accessi ment is to assure operation of the fans 15st all times that cooling is eiected. It will be apparent that this result may also be obtained in the same manner as shown in connection with the humidilcation switches 46 and 49.

Referring to the arrangement shown on the drawing, assume that the

switches

45 and 47 are closed and that the temperature of the air in the space is above a predetermined degree to be maintained. The switches 53 and 54 of the thermostat are therefore closed. A fan circuit is completed from the line conductor L1. conductor 57, switch 47, conductor 58, fan motors 19, conductors 59 to the otherline conductor L2. A circuit is also completed from the energized conductor 58, switch 45, a conductor 64, switch 53, conductor 65, solenoid 36, conductor 59, to the line conductor L2. Another circuit is completed from theenergzed conductor 64, jumper 66, the second pole of switch 45, conductor 67, switch 54, conductor t solenoid 44, to the line conductor L2.

Energization of the solenoid 36 opens the valve 35 to admit refrigerant to the evaporators 13 and energization of the solenoid 44 closes the switches 42 to edectoperation of the refrigerating machine 27. Air discharged by the fans l5 is cooled by the evaporator before it is delivered to the space l0. [When the temperature of the air in the space 10 has been depressed to the desired degree, the thermostat 52 operates to open its switches 53 and 54, thereby deenergizing the

solenoid

36 and 44. Deenergization of the former terminates the iiow of refrigerantto the evaporators 13 and deenergization of the latter stops operation of the refrigj eratlng machine 27. It willbe seen that the fans continue to operate for ventilation as their circuits are independent of the thermostat switches 53 and 54 and the switch 47 is closed.

The other groups of air conditioning devices, (not shown) which are served by the

circuits

38 and 39, are operated in the saine er as the group serving space 10. -All groups eilect operation ot the relay 43 as the conductor 6s is common to all of the groups. .l

From the above description, it will be seen that we have provided a control mechanism whereby a predetermined minimum refrigerating load is e' u: on the refrigerating machine at all times t it is in operation. For example, :t: a e that the reirigerating machine 27 has a capacity equal to six cooling devices similar to the cooling device lil-or 12 and that it is not desirable to operate the reirigeratlng machine with a load les than one-third of its capacity. With the above described control mec, there are 4at least two cooling devices in operation whenever the refrigerating hine 27 is in operation, thereby assuring the predetermined minimum load on the refrigerating machine. This l is sumcient to provide'a suction pressure corresponding to a temperature above the f point, .thereby avoiding frosting or the evaporator.

While we have shown oui-invention in but one form, it will be obvious to those skilled in the art that it is not so ted, but is susceptible of various changes and modifications without departing from the spirit thereof, and we desire, therefore, that only such limitations shall be 'placed thereupon as are imposed by the prior art or as are iflcally set forth in the appended claims. What we claim isz;

1. In a control system for air conditioning 'aratua the combination of a plurality of groups of air cooling devices, a reirigerating ma- 715v e for providing asumir of retxigerant for.

the devices, a plurality oi electrically-operated valves for respectively controlling the ow of refrigerant from said refrigerating machine to of refrigerant for the devices, a plurality of' electrically-operated valves for respectively controlling the ow of refrigerant from said refrigerating machine to the groups of devices, fan switches associated with the devices i'or controlling the operation of their fans, connections for paralleling the switches of each device in a group, whereby closure of one switch initiates operation of all of the fans in the group, cooling switches assoelated with the devices for controlling the' operation of said refrigerating machine, connections between the cooling switches of each device in a group and the valve associated with the group for effecting control of the latter by of the former.

3. In a control system for a plurality of air conditioning devices, each of which includes, an air cooler, a humidifier and a fan for translating air to be treated, meansproviding a supply of liquid for the humidiiiers, electrically operated valves for respectively controlling the ow of liquid from the last -mentioned means to the humidiflers, a refrigerating machine for providing a supply of refrigerant for the air coolers, electrically operated valve means associated with each group or devices for controlling the iiow of refrigerant from the refrigerating machine to the air coolers of the group of devices, a plurality of switches associated with each device and including, a humidiiying switch for controlling the-operation of the humidiiier and the fan, a

cooling switch tor controlling the operation of the retrigerating machine andthe refrigerant valve, and a fan switch for controlling the operation o1' the ian and for rendering the cooling switch operable and inoperable, and connections for paralleling the cooling, humidifying and fan switches of one device in a group with corresponding switches of the other devices in the group, whereby operation of an electrically operated refrigerant valve means serving a group of devices and the refrigerating machine is effected by closure of a ian switch and a cooling sw'itch associated with said group of devices, opf eration of all electrically operated liquid valves and fans associated with the group is effected by closure of any humidifying switch associated with the group, and operation ol all fans associated with the group is effected by closure of any fan switch associated with the group.

4. In a control system for lair conditioning of devices, means responsive to a condition of the air inone of said spaces for` controllingthe op'- eration of the supply me and thev valve .assotherewith. 5. In a 'control systenriorv air' conditioning ciated with 'the""devicesf`servig; saidz space, switches associated With'ech-of 'the devices and connections betweenthe 'switches' associated with a groupof devices and the condition responsive means" associated wlthl the group, -whereby the latter'mean's may" 'b'e' rendered operable and inoperable-"by" any of the lswit'ches connected apparatu's;tli`e combination of a plurality' of groups?4 'of air cooling-devices for respectively cooling the 'airin a plurality ofspaces,'a refrigerating'machine for providing a supplyv of refrigerant forsaid air'coolingfdev-ices, an electrically operated valvefor controlling the ilow of'refrigerant from said machine to each group of devices, means responsive to the temperature of theV air in a space for controlling theoperation `of the refrigeratlng machineand the'valve associated with` the group of devices serving said space, a switch associated with each device in said group, and connections between each of the switches the temperature responsive means whereby the latter may be rendered operable and inoperable by any of the switches.

6. In a control system for air. conditioning apparatus, the combination of a. plurality of groups of air humidifying devices, each of which includes a fan for translating air to be humidiiied, a source vof liquid for said devices, electrically operated valves for respectively controlling the ow of liquidyfrom said source to the air`hum'idifying devices, switches associated with each device for controlling the operation of the valves and fans, and connections between the switches of all the devices in a group for eilecting operation oi all valves and fans in the group when one of the 1switches in the group is moved to its closed posiion.

'7. The combination of a plurality of groups of,v humidiers, for respectively humidifying the airv in a plurality of spaces, a source of liquidfor said -humidiiiersy a' plurality of electrically operated valves for respectively controlling the supply of liquid from said source to the humidiers, humid-y ostats disposed within the said spaces for respec l tively controlling the operation ofthe 'valves'associated with the spaces, a switch associated with each humidifier, connections between .thehumidostat, switches and valves of the-humidifiers serving one of the spacesY whereby the former i.'-

may be rendered operable and inoperable by any of its associated switches, a second switchvassocited with each humidifier, connections between the second switches of all of the humidinera in the group and the fans thereof whereby all of the latter may be controlled by any of the former` and means for operating the-inst and's'e'cond switches of each humidifler simultaneously. v

8; In a control system for air cooling apparatusr plurality o1' air conditioning devices,'each of which includes an air cooler, a humidifier and a fan for translating air to be conditioned, a refrigerating machine for providing a supply of refrigerant for said air coolers, a source of liquid vfor said humidiners, means for controlling the op,-

eration Yof the refrigerating machine and for selectively controlling the supply .of refrigerant to the air coolers so that at least ltwo air coolers are eective at all times that operation of the refrigerating machine is eifected, means for controlling the'operation ofthe humidlers so that atleast two of the same are effective at all times when'they are connected to said liquid source,l

means for eiecting operation ofthe'fans at all times that their associated air coolers or air humidiners are effective and means for eifecting operation of at least two fans forventiiation independently of the last-mentioned means.

v LEWISV R. SMITH.

WILLIAM A. MINKLER.