US2235023A

US2235023A - Air conditioning apparatus

Info

Publication number: US2235023A
Application number: US170168A
Authority: US
Inventors: Komroff Paul; Robert D Lambert
Original assignee: American Radiator and Standard Sanitary Corp
Current assignee: American Radiator and Standard Sanitary Corp
Priority date: 1937-10-21
Filing date: 1937-10-21
Publication date: 1941-03-18
Anticipated expiration: 1958-03-18

Description

Mmmh i8, 194%. P. KUMROFF HTML @$35,023

AIR CONDI-TIONING APPARATUS Filed 001;. 2l, 1937 3 Sheets-Sheet l T IN ENTORS Marl is, 1941, MMROFF mm.. @5,923

AHI CONDITIONING APPARATUS P. KoMRor-'F Erm. v 2,235,023

" ch 18, 19ML.

' AIR CONDITIONING APPARATUS 3 Sheets-Sheet 3 Filed Oct. 2l, 1957 lyEN-rons Hwa aMeof-F 605567227. ff/W55??- l/ l l mA RNEY Patented Mar. 18, 1941 Am CONDITIONING APPARATUS Paul Komrofi, New Rochelle, and Robert D. Lambert, New York, N. Y., assignors, by mesne assignments, to American Radiator t Standard Sanitary Corporation, New York, N. Y., a cor poration of Delaware Application October 21, 1937, Serial No. 170,168

7 Claims.

Our invention relates to air conditioning apparatus, and more particularly to improvements in mechanisms for operating dampers which control the flow of air through such apparatus; the pres- 30, 1940, to Matson C. Terry.

The invention consists in the novel construction and combination of parts, to be more fully described hereinafter, and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of this specification, we have fully and clearly illustrated a preferred embodiment of ourv invention, in which drawings- Fig. l is a perspective view showing air conditionlng apparatus of the room-unit type in which our improvement is embodied;

Fig. 2 is a transverse vertical sectional view through the apparatus shown in Fig. 1, the view being taken on the line 2-2 of Fig, l and being on an enlarged scale;

Fig. 3 is a fragmentary vertical section taken on the same plane as Fig. 2` and showing the damper and its operating mechanism on an enlarged scale Fig. 'l is a fragmentary perspective view with parts in section, showing more clearly the details of the damper and its operating'mechanism;

Fig. 5 is a fragmentary plan sectional view taken on the line 5-5 of Fig. 6;

Fig. 6 is a view similar to Fig. 3, showing they relative position of the parts when the damper is automatically closed due to the non-operation of an air conditioning means;

Fig. 7 is a fragmentary vertical sectional view taken on the line T-'I of Fig. 5;

Fig. 8 is a view similar to Figs. 3 and 6, showing the relative position of the parts when the damper is closed manually; and

Fig. 9 is a perspective view with parts in section, showing in detail the structure of the composite lever for closing the damper when the air conditioning means is not operating.

Referring now in detail to the construction illustrated, and particularly to Figs. 1 and 2, it will be observed that we have shown our improvement as embodied in an air conditioning unit of the type which is adapted to be installed in a room space and adjacent a window opening in an outside wall thereof. The unit is lindicated in general by the reference numeral III, and the 4window by the numeral I I.

'The unit I0 comprises a casing I2 having a room air inlet opening i3 in the top wall and at the rear thereof, and an air outlet opening I4 in the top wall and at the front thereof. The casing I2 is also provided with an outdoor air inlet opening I5 in the upper and rear part thereof, which communicates with one end of a horizontally and rearwardly extending outside air duct I6, and the outer end of the duct I6 being open and adapted to communicate with the outside atmosphere through the opening dened by a partially raised sash I1 of the window II,

Connecting the inlet openings I3 and I5 and the outlet opening I4, is a U-shaped passage I8 which is defined by the outer walls of the'casing I2 and by a partition I9 depending from the top Wall of the casing I2 between the inlet opening I3 and outlet Opening I4, and stopping short of the bottom part of the casing so as to provide the return bend in the lower part of the passage.

Arranged in the upper rear part of the U- shaped passage I8 and adjacent the inner open end of the duct I E, is a damper which is pivotally supported, as indicated at 26,A between the inlet openings I3 and I5, and may be moved about its pivotal support between two extreme positions, one of which closes the inlet opening I5 and opens the inlet opening I3, and the other of which closes the inlet opening I3 and opens the inlet opening I5. As will appear ,more fully hereinafter, the damper 25 may be positioned at any preselected point between these two extreme positions to proportion the amounts of room air and outside air entering the U-shaped passage I3 through the inlet openings I3 and I5 respectively.

It is to be observed at this point that while the damper 25 has just been described as a proportioning damper, it is also correct to, consider the damper as closing and opening the outside air inlet openingl, and also to consider the opening I5 as a part of apassage 28 connecting the outside atmosphere with the room, such passage 28 being formed in part by the duct I6 and in part by the U-shaped passage I8. In the latter sense, the damper 25 opens and closes the passage 2B and thereby regulates the amount of air flowing through said passage 28.

Arranged below the damper 25 and across the passage 28 and U-shaped passage I8, is a suitable iilter 3D which may be removably supported for ready replacement and which serves toremove from the air iiowing through the passage 28 and its part I8, foreign particles, such as dust, dirt, pollen and the like. Arranged below the filter 30, is a cooling coil 3|, which when operating serves to lower the temperature oi .the

air flowing through the passage |8. The cooling coil may be of any suitable construction. The one here shown is of the direct expansion type through which a suitable refrigerant, such, for example, as sulphur dioxide or Freon, is circulated.

Arranged in the lower part of the U-shaped passage |8 is a motor-driven blower unit 32 which provides for the positive flow of air through the passage 28 and into the room through the outlet opening |4. Arranged above the blower 32 and just below the outlet opening |4 is a heating device 33, here shown to be a conventional type of heating coil through which a suitable heating fluid, such, for example, as hot water or steam, is circulated.

In the warmer months of the year when the temperature of the outside atmosphere is above the comfort range of the room space in which the unit I8 is located, the refrigerant is supplied to `the coil 3| and air flowing through the passage 28 and into the room is reduced in temperature so as to produce a desired comfort condition in the room space. During the colder months of the year when the temperature of the outside air is below that of the room space, then the supply of refrigerant is shut oi from the coil 3| and heating iiuid is supplied to the coil 33 andthe temperature of the air flowing through the passage 28 is raised to a point where it will produce a comfortable condition in the room space.

In accordance with the present invention, we have provided an improved mechanism for operating the damper 25, whereby the amount of outdoor air flowing into the room through the unit I8 may be regulated. Regulation is required both in summer and in winter so that the room space will be properly ventilated, and also so that the amount of ventilation can be proper adjusted with respect to the operation of the cooling or heating units to maintain a desired temperature condition in the room space.

Referring now to Figs. 2 to 9 inclusive of the drawings, it will be noted that the damper-operating mechanism is indicated in general by the reference character 35, and comprises a rst rod 36 which is pivotally connected at one end by a pin 31 to the damper 25 at points spaced from the pivot 26, so that the rod 36 and damper 25 will move together. The mechanism 35 also comprises a second rod 38, one end of which extends forwardly through a vertical slot or opening 39 in a front vertical wall part 40 of the duct I6, and the extreme forward end of the rod 38 has a knob 4| which may be grasped by hand for moving the rod lengthwise. The other or rear end of the rod 38 extends rearwardly into the duct I6 and in the` same general direction as the first rod 36. As shown, the

rods

36 and 38 are arranged substantially parallel to one another. The second rod 38 is supported for lengthwise movement by a suitable bracket 43 having a vertical opening or slot 44 therein. The forward end of the rod moves lengthwise through the opening 39.

At the forward end of the rod 38 and in the underside thereof is provided a series oi spaced notches 45, and at the bottom of the opening 39 and on the inside surface of the wall part 48 is fixed a plate 46 which extends slightly above the bottom of the opening 39 and is adapted to engage any desired one of the notches 45 and thereby secure or lock the rod 38 against lengthwise movement at any desired preselected position. When it is desired to move the rod 38 lengthwise to a newV position, the forward end of the rod may be simply raised by grasping the knob 4| and the particular notch 45 disengaged from the plate 46, and the rod'may then be moved at will forwardly or rearwardly. The opening 39 is of suilcient height to permit the necessary clearance between the notches 45 and plato 4l when the rod is lifted.

The mechanism 35 also comprises a link 58 connecting the first and

second rods

36 and 38 at the rear ends thereof. The link 50 is pivotally connected to the rear end of the second rod 38 by a suitable pin 5|, and is pivotally connected to the rear end of the rod 36 by a pin 52 extending transversely through a slot 53 formed in the first rod 36 and-extending lengthwise thereof. A compression spring 54 engaging at one end an abutment formed by a transverse pin 55 in the rear end of the rod 36, and engaging at the other end the lower part of the link 58, serves to hold the pin 52 tightly against the forward end of the slot 53 (see Figs. 3 and 4). nection provided by the pin 52, slot 53 and spring 54, will appear more fully hereinafter.

Fixed to the connecting link 58 and projecting forwardly at the side thereof adjacent the damper is an abutment 51 which is adapted to engage the lower end of an adjusting screw 58 which, functionally, is a part of the rod 38. The

screw 58 extends through a threaded opening in the rod 38 and serves to secure the proper positional relationship between parts. When the abutment 51 is in engagement with the screw 58, relative movement is prevented between the link 50 and

rods

36 and 38, should the rod 38 be moved in a damper-closing direction, and should the rod 36 be moved in a damper-opening direction.

The mechanism 35 also includes a tension spring 59 connecting the

rods

36 and 38 at points spaced forwardly from the link 58. The spring 59 is so arranged that it functions to urge the rod 36, damper 25 and link 50 forwardly with respect to the rod 38, and thereby effect engagement between the abutment 51 and the screw 58 which, as stated, is a functional part of the rod 38. This is made possible, due to the fact that the spring 59 and link 58 are inclined toward one another in the direction extending toward the rod 36. It will be apparent that as the spring 59 holds the abutment 51 tightly against the screw 58 of rod 38, the Iparts are held together as a unit and the damper may be moved to any preselected position by the manual lengthwise movement of the rod 38.

Figs. 2, 3 and 4 show the relative position of parts when the rod 38 is adjusted to position the damper so as to partially open the inlet opening I5. Fig. 8 'shows the relative position of the parts when the rod 38 is adjusted to close the damper 25. the forward notch 45 on the rod 38 engages the plate 46, and that the pin 52 is spaced from the forward end of the slot 53. The lpurpose of the .lost-motion connection provided by the pin 52,

slot 53 and spring 54, is to permit the rod 38 to be moved inwardly beyond the point where the damper 25 is closed and against the force of the spring 54. The spring 54 will then serve to hold the damper tightly in its closed position. This construction is advantageous because a tight closing of the damper may always be assured without the necessity of extreme accuracy The purpose of the lost-motion con- In Fig. 8, it will be observed that assauts in. manufacture, assembly and adjustment oi' the

rods

36 and 38 and the link 55.

In accordance with the present invention, we also provide as a part of themechanism 35, a means which acts in response to an operating characteristic of an air conditioning element for automatically closing and opening the damper 55 and thereby regulating the amount of outdoor air iiowing through the passage 25. In the illustrated embodiment of our invention, we have shown this means as including a thermostat 55 which acts in response to the temperature of the air flowing from the heating coil 33 to control the operation of a heat motor i, the latter bcing operatively connected to the damper by a suitable chain 62 (see Fig. 5).

The operation of the means just referred to is such that when' the temperature of the air passing from the heating coil 33 falls below a pre-A determined minimum, the heat motor 6l operates to pull the chain 52 taut and close the damper 25 against the force of the spring 55. The heat motor 5l will hold the damper tightly closed until the temperature of the air owing from the coil 33 rises above the aforementioned predetermined minimum. When the latter occurs, the heat motor acts to release the damper 25 and the spring 53 returns the damper to a position determined by the preselected secured position of the rod 33. v

The heat motor is enclosed within a housing 5ft supported by a wall of the duct I6, and comprises a cylinder 65 secured to a wall 65 of the housing 64, an expansible metallic bellows 6l located within the cylinder 65 and fixed at one end to the wall 55, a rod 63 xed at one end to the movable end of the bellows 6l and the other end extending throughan opening B5 in the wall 55, and a compression spring 15 encircling the rod 55 and abutting at one end the wall 65 and at the other end the movable end of the bellows (see Figs. 5 and 7). l f

The heat motor 5l also comprises a composite lever 'l l which is fulcrumed intermediate its ends as indicated at 'l2 and is pivotally connected at one end to the outer end of the rod 68 (see also Fig. 9). The other end of the lever is connected by the exible chain 52 with the damper 25. The compositelever ll comprises an element 'l5 including a web portion 'I6 and lateral right-angle flanges ll.- The flanges 'il receive a pin 'l5 which forms a part of the iulcrum l5, and is supported from the wall 55 by spaced brackets l5. The outer end of the rod 55 is secured by a suitable pin 55 to one of the ilanges ll. The composite lever also comprises an element 5l pivotally mounted on the iulcrum -pin "l5, and secured to the element 'l5 by a pin 55 passing through the element 5l and one of the ilanges 'lll of the element l5. The flexible chain 55 is connected at one end to the outer end of the element 5l, and is connected at the other end to the pin 5l carried by the damper 55.

The heat motor also comprises an electrical heating element 55 encircling a small chamber 55 positioned in the housing 55, and the chamber is connected toI the cylinder 55 by a small tube 5l. The chamber 55, tube 5l' and the space in the cylinder 55 outside oi `the bellows 5t, are adapted to be filled with any suitable expansible i'luid, such, for example, as ethyl chloride, sulphur dioxide, ether, or the lilre.

rli'he electrical heating element 55 is connected in an electrical. circuit with the thermostat 55 by conductors dit. The 'thermostat may be oi' any suitable construction, depending upon the type of control desired. The one here shown operates to close the electrical circuit when the temperature of the air engaging the thermostat is above a predetermined point, and to open the circuit when the temperature of the air falls below the predetermined point.

When the thermostat 65 closes the electrical circuit, the heating element 55 is energized, which results in the vaporization of the iluid in the chamber 86, tube 8l and cylinder 65, and in the compression of the bellows 6l. As the bellows is compressed, the rod 6B moves outwardly of the housing 65 against the force of the cornpressicn spring 'l5 and moves with it the lever 'll in a direction to put slack in the chain 62 and permit the spring 59 to move the damper to the position preselected by hand adjustment of the rod 33. When the thermostat 65 opens the electrical circuit, the element 85 is deenergized. This will result in the contraction of the expansible fluid in the chamber B6 and in the compression spring moving the bellows 5l back to its fully extended position, and moving with it the rod B8 and lever 1l and pulling the chain B2 taut and closing the damper 25.

In the embodiment illustrated, the normal con-y dition is the one Where a heating iiuid is supplied to the coil 33. As stated previously, when heat is in thev coil 33, the thermostat 6I] is closed and the heating element 55 is energized and the damper 25 opened. This position is the one `shown in Figs. 2, 3 and 4 of the drawings. With the parts in this position, the damper 25 may,

be moved to any new position by simply moving the rod 38 forwardly or rearwardly by hand in the manner previously explained. `Should the supply of heating uid be shutioi for any reason, the thermostat 55 will open the circuit, deenergize the heating element 55, and close the damper in the manner before explained. lflhe closed position is shown in Figs. 5 and 6 of the drawings. It will be noted from an examination of Fig. 6 that the abutment 5l has been moved away from the screw 55 of rod 35. With the heating element 55 deenergized, the damper cannot be opened. However, the position to which the damper will move when the heating element again becomes energized, can be changed by moving the rod 33 in or out in the manner explained previously. This is permitted, due to the spring and link connection between the rod 35 and the rod 35.

From the above, it is apparent that we have provided a mechanism which permits the damper to be accurately adjusted by hand to any preselected position, and which at the same time provides for the automatic closing of the damper in response to changes in an operating characteristic of an air conditioning element. While we have shown the mechanism 55 as operating in response to the temperature of the heatingcoil it is to be noted that the invention is not limited in all oi its aspects to this particular arrangement; ior, insofar as the broader aspects of the invention' are concerned, the mechanism 55 may operate in response to an operating charto mean any condition which reflects the operation of the air conditioning means; that is to say, any condition which indicates or shows whether or not the air conditioning means is operating, or its degree of operation, or the air conditioning effect produced by the airconditioning means because of its operation. One example of an operating characteristic of the air conditioning means would be the temperature of the air leaving the heating coil 33, as described above. The temperature of the air leaving the coil changes with the heat output of the coil and thereby indicates whether or not the coil is operating. Other examples of operating characteristics of an air conditioning means would be the surface temperature of a heating or cooling coil; the temperature of a heating or cooling medium fiowing through a heating or cooling coil; the rate of fiow of a cooling or heating medium through a coil; and the pressure of the fluid inside of a coil as in the case of a steam coil and in the case of a refrigerant in a cooling coil. Obviously, any operating characteristic of the air conditioning means may be used as a source of control for the opening and closing of the damper 25, without departing from the intended scope of the present invention.

It is advantageous to have a damper which may be adjusted at will to regulate accurately the amount of outdoor air fiowing into a room which is being air conditioned. In the Winter time, the amount vof outdoor air entering the room has a direct effect on the ability of the heating coil to maintain a desired temperature in the room, and should the heating coil fail to operate, it would be desirable to close the outdoor air inlet so that the comfortable condition could be maintained in the room, and so as to prevent cold f drafts. Furthermore, continued flow of cold outside air might damage the unit by freezing the water-filled parts therein.

The apparatus described above can perform these desired functions in an admirable manner. The position of the damper may be easily and quickly adjusted, and the mechanism for posi- .tioning the damper does not interfere in any way with the automatic closing and opening `of the damper when required. The two

rods

36 and 38, the link 50, with the abutment 51 and the tension spring 59, make the performance of these functions possible.

What we claim and desire to secure by Letters Patent of the United States is:

1. In air conditioning apparatus, means defining an air passage; means for changing the condition of the air flowing through said passage; a damper movable between closed and open positionsfor regulating the flow of air through said passage; a first rod connected at one end to the damper and movable lengthwise with the damper; a second rod extending in the same general direction as said first rod and spaced therefrom and movable lengthwise by hand; means for securing said second rod against lengthwise movement at any one of a plurality of positions; a

connecting link pivoted at oneA end to the first rod and pivoted at its other end to the second rod; abutment means on said link and adapted ,to engage one of said rods and prevent relative movement therebetween when said first rod is moved in' a damper-opening direction and when ment into said engagement with the ro'd so that the first and second rods and connecting link are normally held together for movement as a unit for adjusting the position of the damper; and means acting in response to changes in an operating characteristic of said air conditioning means for moving said damper in a closing direction against the force of said urging means upon a givenreduction in output of said air conditioning means.

2. 1n air conditioning apparatus, means defining an air passage; means for changing the condition of the air flowing through said passage; a dampermovable between closed and open positions for regulating the ow of air through said passage; a first rod connected at one end to the damper and movablelengthwise with the damper; a second rod extending in the same general direction as said first rod and spaced therefrom and movable lengthwise by hand; means for securing said second rod against lengthwise movement at any one of a plurality of positions; a connecting link pivoted at one end to the first rod and pivoted at its other end to the second rod; abutment means on said link and adapted to engage one of said rods and prevent relative movement therebetween when said first rod is moved in a damper-opening direction and when said second rod is moved in a damper-closing direction; means for constantly urging said abutment into said engagement with the rod so that the rst and second rods and connecting link are normally held together for movement as a unit for adjusting the position of the damper; and means for closing said damper against the force of said urging means when said condition-changing means is not operating and permitting said urging means to open said damper tov a point determined by the preselected secured position of said second rod when the condition-changing means is operating.

3. In air conditioning apparatus, means dening an air passage; means for changing the condition of the air flowing through said passage; a damper movable between closed and open psitions for regulating the flow of air through said passage; a first rod connected at one end to the damper and movable lengthwise with the damper; a second rod arranged in spaced substantially parallel relation with the rst rod and movable lengthwise by hand; means for securing said second rod against lengthwise movement at any one of a plurality of points; a connecting link pivotally connected at its ends to said first and second rods, respectively; abutment means on the side of said link which is adjacent said damper' and adapted to engage said second rod and prevent relative movement therebetween when said first rod is moved in a damper-opening direction and when said second rod is moved in a damper-closing direction; a tension spring connecting said first and second rods at points spaced from said link and between the link and damper and extending in an inclined direction with respect to said rods so as to constantly urge said abutment means into engagement with Said second rod, and so that the first and second rods and connecting link are normally held together for movement as a unit for adjusting the position of the damper; and means for closing said damper against the force of said spring when said condition-changing means is not operating and permitting said Spring to open said damper to a point determined by the preselected secured p0- sition of said second` rod when the conditionchanging means is operating.

4. In air conditioning apparatus, means defining an air passage; means for changing the condition of the air flowing through said passage; a pivoted damper movable between open and closed positions lor regulating the flow of aifr through said passage; a first rod pivotally connected at one end to said damper at points spaced from the pivotal axis and extending away from the latter in a direction transverse to the pivotal axis so that the rod may be moved lengthwise for opening and closing the damper; a second rod spaced from said first rod and extending from points adjacent said damper in the same general direction as said first rod; means providing for lengthwise movement of said second rod by hand and for securing said second rod against lengthwise movement at any one of a plurality of positions; a connecting link pivoted at one end to the rst rod and pivoted at its other end to the second rod; abutment means on said link andadapted to engage one of said rods and prevent relative movement therebetween when said rst rod is moved in a damperopening direction and when said second rod is moved in a damper-closing direction; means for constantly urging said abutment into said engagement with the rod so that said first and second rods and said connecting link are normally held together for movement as a unit for adjusting the position of the damper; and means for closing said damper against the force of said urging means when said condition-changing means is not operating and permitting said urging means to open said damper to a point determined by the preselected secured position of said second rod when the condition-changing means is operating.

5. ln air conditioning apparatus, mean denning an air passage; means for changing the condition of the air owing through said passage; a damper movable between closed and open positions for regulating the flow of air through said passage; a first rod connected at one end to the damper and movable lengthwise with the damper; a second rod extending in the same general direction as said flrstrod and spaced therefrom and movable lengthwise by hand; means for securing said second rod against lengthwise movement at any one of a plurality of positions; a connecting link pivoted at one end to the first rod and pivoted at its other end to the second rod; abutment means on said link and adapted to engage one of said rods and prevent relative movement therebetween when said first rod is moved in a damper-opening direction and when said second rod is moved in a damper-closing direction; a tension spring connecting said rods at points spaced from said connecting link and extending in an inclined direction with respect to said rods so as to constantly urge said first rod, connecting link and damper to move in a damper-opening direction and eiect said engagement between the abutment means and one of said rods, whereby movement of said second rod by hand will result in said link, said rst rod and said damper moving therewith as a unit; and means connected to said damper for closing the latter against the force of said spring when said conditioning means fails to operate and permitting said spring to return the damper to the position determined by the preselected secured position of said second rod when said condition-l ing means operates again.

6. In air conditioning apparatus, means dening an air passage; means for changing the condition of the air owing through Vsaid pas sage; a damper movable between closed and open positions for regulating the flow of air through said passage; Iirst and second rods arranged in spaced substantially parallel relation; said rst rod being connected at one end to said damper for lengthwise movement therewith and said second rod being movable lengthwise by hand to any one of a plurality of positions; means for securing said second rod against lengthwise movement at any of said positions; a link connected at its ends to said first and second rods, respectively, a tension spring also connecting said rods and at points spaced from the link and at the damper side of the latter; abutment means on said link and on the side thereof adjacent said spring and adapted to engage said second rod; said link and said spring being inclined toward one another in the direction extending toward said first rod so that the spring tends to hold said abutment means against said second rod and so that normally, said rst rod, link and damper may be moved manually as a unit with said second vrod for positioning the damper; and means for closing said damper against the force of said spring when said condition-changing means is not operating and per mitting said spring to open said damper to a point determined by the preselected secured pol sition of said second rod when the conditionchanging means is operating.

7. In air conditioning apparatus, means defining an air passage; means for changing the condition of the air flowing through said passage; a damper movable between closed and open positions for regulating the ow of air through said passage; a first rod connected at one end to the damper and movable lengthwise with the damper; a second rod extending in the same general direction as said first rod and spaced therefrom and movable lengthwise by hand; means for securing said second rod against lengthwise movement at any one of a plurality of ,separate and distinct positions; a connecting link; a pivotal connection between one end of said link and one of said rods and'a second pivotal connection between the other end of said link and the other of said rods; abutment means on said link and adapted to engage one of said rods and prevent relative movement therebetween when said first rod is moved in a damperopening ldirection and when said second rod is moved in a damper-closing direction; means for constantly urging said abutment into said engagement with the rod so that the first and second rods and connecting link are normally held together for movement as a unit for adjusting the position of the damper; one of said pivotal connections comprising a, lost-motion connection including a spring for taking up the lost motion and being so constructed that said second rod can move after the damper is closed in a damper-closing direction and against the force of the spring, and can be secured at a position past the point Where the damper is closed with the spring holding the damper tightly closed; and means for closing said damper against the force of said urging means when said condition-changing means is not operating and permitting said urging means to open said damper to a point determined by the preselected secured position of said second rod when the condition-changing means is operating.

PAUL KOMROFF. ROBERT D. LAMBERT.