US2901961A - Floor register with adjustable louvers - Google Patents

Description

L.-C. COTTS FLOOR REGISTER WITH ADJUSTABLE LOUVERS Sept. 1, 1959 2 Sheets-Sheet 1 Filed Sept. 4, 1956 W M fill T M w INVENTOR.

| c. coTTs 2,901,961

FLOOR REGISTER WITH ADJUSTABLE LOUVERS 2 Sheets-Sheet 2 Sept. 1, 1959 Filed Sept. 4, 1956 INVENTOR.

Carri United States Patent FLOOR REGISTER WITH ADJUSTABLE LOUVERS L'ouis C. Cotts, Michigan City, Ind.

Application September 4, 1956, Serial No. 607,878

11 Claims. (Cl. 98103) This invention relates to improvements in floor registers used in conjunction with warm air heating systems, air conditioning systems, or combination systems for both heating and cooling, and each of the forced flow type.

The usual practice in the manufacture of floor registers for use in systems for heating or air conditioning which are of the forced air type, is to provide the same with air directing or diverting louvers. These louvers are usually fixed to the housing of the register and are located at different angles for the purpose of permitting substantially vertical discharge of air through the central portion of the register while deflecting laterally the air discharged from the opposite ends of the register, so as to increase the lateral throw of air discharged from the register. These fixed louvers are usually ineffective for projecting air laterally from the ends of the register to any substantial distance because they are generally narrow in width and of small surface area so that they do not materially deflect air flow therepast. The narrowness of the blades requires close spacing thereof and use of a large number thereof, with the result that a high resistance to flow of air through the register is encountered.

Another characteristic of conventional registers is that, if a damper is used therein, it must be separate from the air-deflecting vanes or louvers. Such separate damper serves merely to control the rate of flow of air which impinges upon the turning vanes. If the rate of flow of air through the register is small, little directional control is provided by the vanes or louvers, and the pattern of the air discharged from the register is narrow rather than flared or laterally elongated, and differs very little from the pattern of air discharged from a register of a convection or gravity type warm air heating system. The use of dampers in addition to turning vanes or louvers has the further objection of rendering the construction expensive because of the large number of parts employed therein and the high cost of fabrication of the parts and their assembly.

It is the primary object of this invention to provide a floor register which is simple in construction, which is comparatively inexpensive, which is easy to adjust, which reduces to a minimum the number of parts required in fabrication thereof, and which overcomes the disadvantages mentioned above with respect to prior floor registers.

A further object is to provide a register having a plurality of louvers rotatably mounted therein and individually adjustable between a closed position substantially preventing flow through the register and an open position in which the flow of air is substantially unretarded but is directionally controlled as selected or set manually.

A further object is to provide a register with a plural-ity of rotatable louvers and means for rotating said louvers individually and through different angles for presenting difierent direction control factors at different louvers.

A further object is to provide a register having rotatable louvers arranged in groups and means for rotating the louvers arranged in each group progressively and successively to a final flow directing position in which each louver in each group is differently oriented with respect to the direction of flow of air therepast so as to possess a direction control function dilferent than each of the other louvers.

A further object of the invention is to provide a register with rotatable louvers and means for successively rotating the same so as to maintain the velocity of air flow and the directional controlling properties of the device when low output settings of the register are made by adjusting the control at a partially open position only.

A further object is to provide a register having rotatable louvers with means for rotating said louvers from a closed position progressively and successively to different angular settings and with separate means for rotating said louvers to similarly oriented open positions.

Other objects will be apparent from the following specification.

In the drawings:

Fig. 1 is a fragmentary perspective view of one embodiment of the invention and illustrating the louvers thereof in closed position;

Fig. 2 is a longitudinal vertical sectional view taken on line 22 of Fig. 3, and illustrating one group of louvers in open position and a second group of louvers in closed position;

Fig. 3 is an enlarged vertical transverse sectional view taken on line 33 of Fig. 2;

Fig. 4- is a fragmentary vertical longitudinal sectional View similar to Fig. 2 and illustrating a modified construction of the device;

Fig. 5 is an enlarged longitudinal vertical sectional detail view similar to Fig. 2 and illustrating a modified construction of louver-actuating means with the louvers thereof in closed position;

Fig. 6 is a longitudinal sectional view taken on line 6-6 of Fig. 5;

Fig. 7 is a view similar to Fig. 5 but illustrating the parts in a different setting or adjustment thereof;

Fig. 8 is a longitudinal sectional view taken on line 8-8 of Fig. 7;

Fig. 9 is a longitudinal vertical sectional view similar to Fig. 5 and illustrating a third operating position of the louvers;

Fig. 10 is a longitudinal sectional view taken on line 10-10 of Fig. 9; and

Fig. 11 is a fragmentary vertical transverse sectional view of a register employing the construction illustrated in Fig. 5 and taken on line 11-11 of Fig. 5.

Referring to the drawings, and particularly to Figs. 1 to 3, the numeral 10 designates side walls, and the numeral 12 designates the end walls of the frame of a heat register, preferably of substantially rectangular elongated outline. O utturned flanges 14 are provided at the upper margins of the walls 10 and 12 and have connected thereto an apertured margin defining top plate or face plate 16 whose aperture preferably substantially coincides with the passage defined by the walls 10 and 12. The plate 16 bears upon and is preferably secured to flooring 18 of a building around an opening 20 therein through which the register depends. The register is connected at its lower margin with a boot 22 connected with a conduit (not shown) of an air circulating and distributing system, such as a forced air heating system or a forced air circulating cooling system. A plurality of longitudinal spaced bars or tread members 24 are carried by the register end walls 12 with their upper edges substantially flush with the top surface of the top plate 16.

A plurality of louvers 26 are arranged in the register to e tfind transversely thereof. Each louver is preferably, though not necessarily, of curved or arcuate crosssectional'form. Each louver'preferably has legs 28 extending perpendicularly therefrom at the ends thereof and is apertured to receive a pivot pin 30 passing through an aperture in'the' adjacent side wall 10. 'The pivot pins 3% (Sf-each louver are axially aligned and are preferably located substantially'centrally'of the louver so that each louver can rock about an axis "transverse of the register and lengthwise of itself. The-louvers are preferably cut out at a part of each end 32 thereof. Each longitudinal edge of eachlouver 26 is preferably curved oppositely to'the curvature of the louver to define a longitudinal reinforcing lip 34. At one end thereof, and preferably at'the cut-away portion 29,- each louver is provided with an'arm 36-bent angularly therefrom in a direction opposite'to'the legs 28. Thus the arm 36 is here shown as=extending or projecting from the convex face of the louver and the legs 23 are shown as projecting from the-concave surface of the louver. The arms 36 preferably are'laterally offset from the legs 28.

In the construction illustrated in Figs. 1 and 2, the endmost louvers 27 are transversely curved for a portion only of the width thereof, and the remaining outer portion 29 thereof is substantially flat. The louvers 27 also are preferably wider than the louvers 26, as best seen-in Fig. 2.

The louvers 26 and 27 are'pivoted at substantially equispaced points along the longitudinal walls of the register and in such-positions that the marginal flanges 34 of adjacent louvers overlap, as illustrated at the right in Fig. 2, when the louvers are in closed position substantially'horizontally oriented relative to the register.

The louvers are preferably arranged in two sets or groups, as illustrated in Fig. 2, with the louvers ineach set being adapted to swing in a direction opposite to the direction in which the louvers of the other set swing between closed position, as shown at the right in Fig. 2, and open position, as shown at the left in Fig. 2. In the form of the device illustrated in Figs. 1 and 2, the louvers of each group are interconnected and associated bymeans'of a common actuator. Each of these actuators is of the character adapted to progressively and successivelymove or rotate the louvers of the associated group during its movement from a fully closed position tora fullyopen position. In other words, the arrangement is such that initial movement of the actuating means froma closed position toward an open position will open or rockv the innermost louver ofthe set only. Then after a predetermined amount of movement of the innermost louver has occurred, the actuator will commence movement of the next outer louver together with the inner louver. Then, after further movement of the actuator, the'rnextouter louver is-movedalong with the two inner louvers. This progressive pick-up of the louvers requires lostmotion means associated with each louver and having different degrees of play. The parts are preferably so arranged thatiby thetime the actuating means reaches fully :open position all of the louvers will have been moved to'some degree, but the outermost louver will have been moved only a slight extent compared to the innermost louver, and the intervening louvers will have been'progressively moved between the minimum opening. of the outer louver and the maximum opening of the innermost louver of the group.

The lostmotion actuating means for accomplishing the progressive opening of the louvers of each group may take various forms. I have illustrated in Figs. 1 and 2) .one form which this means may take, which constitutes anelongated bar 40 extending alongside one side wall o-f'the register to be shiftable longitudinally thereof, as by means .of'a handle portion 42 projecting upwardly between a side wall and one of the tread members 24. The-innermost'louver of the'groupwith which the actuator 40 is associated has its arm 36 pivoted to the actuator at 44 on an "axis fixed with refr t0 th actuator. The successive louvers 26 and 27 have pivot pins '46, 48 and 50 projecting from the respective arms 36 thereof and passing freely into longitudinally spaced apertures 47, 49 and 51, respectively, formed in the bar it The apertures 47, 49 and 51 are of progressively different lengths and preferably are of a width or height greater than the diameter of the pins 46, 48 and 50 passing therethrough. The leading edges of the openings 47, 49 and.51,.that..is, ,theleft-hand edges of the openings in the right-hand bar, as seen in Fig. '2, are spaced apart uniformly a distance substantially equal to the spacing of the pivot axis 30 of the louvers.

The arrangement of the louvers and the-actuating means therefor with respect to each other and to the register frame is such that initial movement of the bar 40 from a closed position, as illustrated at the right in Fig. 2, toward an open position will entail movement or rocking of the central or innermost louver 26 only until such time as'the trailing edge of the aperture 47, which is spaced from the pin $6 'in the closed position of the louver, strikes that pin, whereupon the louver associated with the pin 46 is rocked along with the innermost louver. The two innermost louvers are then rocked together until the trailingedge of the aperture 49 engages the pin 48, whereupon the louver associated-with the pin 48 is actuated by further movement of the bar 40. Ultimately, the trailing edge of the aperture 51 strikes the pin 50, so that'final movement of the actuating member toward its innermost position, as illustrated at the left in Fig. 2, entails pivoting of all of the louvers simultaneously.

The parts are preferably so arranged that the inner most louver will be rocked through an angle of approxi mately degrees to a fully open position by the full travel of the member 40, and each of the other louvers will be rocked to progressively lesser degrees. For example, the second louver may be rocked through an angle of 67 /2 degrees, the third louver may be rocked through an angle of 45 degrees, and the fourth louver may be rocked through an angle of 22 /2 degrees. It will be understood, however, that the angular displacements aforementioned are illustrative and are not intended to be limiting, and that any desired rocking of individual louvers may be provided by simply controlling the amount of lost motion of that louver with the actuating means. It will be apparent, as illustrated in Fig. 2 at the left, that the various louvers deflect air forced there-through to-different extents and degrees in their final position. Thus the central louver has very little air-deflecting action. The next outer louver, being somewhat inclined, has a slight deflecting property. The next louver producesrnore deflection, and so on, with the result that the outermost louvers deflect the air impinging thereagainst to substantial extent. The deflection of the air may result solely from the angular position of the louver or partly from such angular position and partly fromthe transverse curvature of the louvers. Thus an assured lateral throw or spread of the air discharged through the register is assured when the register is infully open position. When the register is in only partially open position, the louvers serve as dampers to restrict the fiow of air through the register. It is important to observe, however, that this restriction of the flow of air occurs without sacrifice of velocity of the air which is discharged, so that there is no dissipation of the direction controlling characteristics of the device in cases where the actuator is .set at a position to open only some'of the louvers and.to position the others in their closed and flow-retarding positions. The double function played by the louvers, namely, the function of dampers when closed, and the function of deflectors when open, eliminates the need for separate or individual dampers and thereby assures: that the number of parts required in the device is heldat. a minimum, so. that the cost of fabrication and assembly of the construction is held low.

In cases where the end walls 12 of the register are Substantially vertical, as illustrated in Fig. 2, it is necessary to employ an arrangement wherein the outermost louvers 27 are wider than the remaining louvers 26. It is possible, however, to construct the device in such a manner that each of the louvers 26 employed in the device is of the same size and configuration, and such a construction is illustrated in Fig. 4. The end walls 52 of the register frame flares upwardly and outwardly and preferably is curved. The outermost louver is similar to the other louvers and abuts the end wall intermediate its height in closed position. If desired, a shoulder 54 may be provided to accommodate such abutment and provide space for the free end of bar 40. The curvature of end wall part 54 is preferably of the same order as the curvature and angular displacement of the outermost louver when fully open, as illustrated in dotted lines in Fig. 4, so as to cooperate with the outermost louver in defining a deflecting passage at the end of the register which is of substantially uniform cross-section. The side walls of the register of the Fig. 4 construction are preferably flat and substantially vertical, as illustrated in Figs. 1 and 3, and the construction and arrangement of the parts will otherwise be similar to that illustrated in Figs. 1 to 3 in that the actuating means will have different amounts of lost motion with respect to the different individual louvers so that progressive amounts of actuation or rotation of the louvers occur incident to the operation of the actuator 40*.

In instances where the register is to function as the outlet for air in an air cooling system or in a combination heating and cooling system, it may be desirable to adjust the device in open position with the varying directional properties of the louvers omitted so that minimum resistance to discharge or flow of air from the register may be provided. Such an arrangement may be provided by incorporation of an additional lost motion actuating mechanism operable independently of the actuating mechanism which functions to move the louvers to different angles as described above. Thus there may be associated with the mechanism illustrated and described in Figs. 1 to 3 an additional mechanism capable of functioning after the primary actuating mechanism 40 has moved to fully open position. The purpose of such additional actuating mechanism is to move to fully open position each of the louvers which were only partially opened by the operation of the primary actuating mechamsm.

A construction of this character is illustrated in Figs. 5 to 11 and entails the provision of a second bar or rod 60 located alongside the bar 40 and having a handle or grip portion '62 projecting therefrom within convenient reach of a user by inserting a finger between one side wall of the register and a tread member 24. The bar 60 will preferably be of shorter length than the bar 40, as best seen in Figs. 6, 8 and 10, so that in the closed position of the louvers the inner end thereof will be spaced from the pivot pin 44 connecting the innermost louver 26 to the bar 40. The bar 60 has slots 67, 69, 71 therein to receive and accommodate each of the pivot pins 47, 49 and 51, respectively, carried by the arms 36 of the remaining louvers 26 and 27. The slots 67, 69 and 71, in the form here illustrated, are longitudinally elongated to accommodate free play or movement of the pins 46, 48 and 50 therein incident to operation of the actuator 4t) to shift the louvers from closed to open position.- The arrangement is such that the trailing edges of the slots 67, 69 and 71, that is, the right-hand ends or edges thereof as illustrated in Fig. 6, are substantially equally spaced. The longest slot is the slot 67 accommodating the pin 46 which travels in the shortest slot 47 of the actuator 40. The slot 69 is of intermediate length, and the slot 71 is of shortest length and receives the pin 50 which travels in the slot 51 of longest length in the member 40.

I The slots 67, 69 and 71 are of such lengths as to ac- 6 commodate substantially full movement of the actuator 40 to shift the various pins 44, 46, 48 and 50 associated with the louvers without altering the position of the bar 60. This arrangement is illustrated in Figs. 7 and 8 wherein the bar 46 has moved to its fully open position but the bar 60 remains in the same position it occupied in the closed position of the louvers, as illustrated in Fig. 5. It will be observed, however, that each of the pins 46, 43 and Si will have moved to the leading end of the respective receiving slots 67, 69 and 71 when the member 4% has reached its fully open position.

After the parts reach the position illustrated in Figs. 7 and 8 with the louvers open to different degrees or extents, it is possible to shift the louvers to fully open position by moving the bar 60 to the position illustrated in Fig. 9. As this movement occurs, the trailing or righthand end of the shortest slot 71 in the member 60, as viewed in Figs. 9 and 10, first contacts the pin 50 associated with the outermost louver and shifts the same until it has been moved to the same tilted angle as the next adjacent louver. Then the trailing end of the slot 69 will engage the pin 48 to pick up the same and thereafter move the louvers associated with said pins 48 and 5t!) simultaneously until they both reach the angle of opening of the next adjacent louver, whereupon pin 56 is engaged by the trailing end of the slot 67 and all louvers except the innermost louver are then moved toward open position until they reach fully open position, as illustrated in Fig. 9. It will be observed that in the position shown in Figs. 9 and 10 the pins 46, 48 and 50 have been advanced to the leading or left-hand edges of the slots 47, 49 and 51 of the member 40.

When it is desired to close the louvers to the positions illustrated at the right in Fig. 2, the actuator 40 is moved toward the right from the position shown in Fig. 9. Since the pins 46, 48 and 54 are then engaging the trailing or right-hand ends of the slots 67, 69 and 71, as viewed in Fig. 10, the movement of the member 40 will carry along with it the member 69 until the parts are restored to the position illustrated in Fig. 5.

While it may be desirable in most instances to provide the device with actuating means, such as the actuators 49 and 6f? which serve to actuate groups or all of the louvers of a register incident to one actuation thereof, it is not essential that such actuating means be provided. Instead, each of the arms 36 associated with the respective louvers may be made of such length that they can be grasped and manipulated individually and manually by users reaching through the grating at the upper part of the register defined by the tread members 24. In such instances it is desirable to provide sufficient friction at the pivots 23, 36 which mount the louvers, to insure that the louvers will maintain any position in which they are set. In such instances the louvers can serve the same dual function of air deflection or direction flow control, on the one hand, and as dampers on the other hand, which has been described above. Such individual adjustment has advantage in certain instances by permitting selected deflection of air at all parts of the register.

While the preferred embodiments of the invention have been illustrated and described, it will be understood that changes in the construction may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. A floor register adapted for connection with a forced air circulating system, comprising a frame having side and end walls and defining an air outlet, a plurality of louvers pivoted in said frame on parallel axes and cooperating to substantially close said outlet in one position thereof, and means in said frame adjacent one end of said louvers for rocking a group of said louvers, said means having lost motion connection with said selected louvers of said group, and a second independently operable means in said frame adjacent an end of said louvers 7 and having lost motion connection with the louvers, of the same group, to rock; said selected louvers more than taste roc ed by d ir t me n Z A fioor registeradapted for connection with a forced air circulating system, comprising a frame having side and. end walls and defining an air outlet, a plurality of louvers pivoted in said frame on parallel axes and cooperating to substantially close said outlet in one position therecf, and means for rocking a group of said louvers, said means having lost motion connection with selected louvers of said group, and a second independently operable means for rocking the louvers of the same group, said sccond louver-rocking means having lost motion connections with said louversand being operable to rock said selected; louvers, beyond the position to which they are rocked by said first means.

3. A floor register adapted for connection with a forced air circulating system, comprising a frame having side and, end walls and defining an air outlet, a plurality of louvers pivoted in said frame on parallel axes and cooperating to substantially close said outlet in one position thereof, and an elongated member shiftable endwise in said frame and transversely of said louver pivot axes, means connecting said member to the louvers of a group spaced from the pivot axes of the louvers, at least one of said connection means accommodating lost motion of said member relative to a louver, and a second elongated member substantially parallel to and shiftable independently of said first elongated member, said second elongated member having lost motion connection to the lou vers having lost motion connection with said first member and being operable to rock the louvers having lost motion, connection with said first shiftable member beyond the position to which they are rocked by said first member.

4. A floor register adapted for connection with a forced air circulating "system, comprising. a frame having side and end Walls and defining an air outlet, a plurality of louvers pivoted in said frame on parallel axes and cooperating to substantially close said outlet in one position thereof, an elongated bar shiftable in said frame transverse of said pivot axes and having a plurality of longie tudinally spaced openings, means carried by said louversspaced from their pivot axes and extending into said openings, some of saidopenings being elongated whereby movement of said bar partially actuates selected louvers, and a second independently shiftable elongated bar sub-.. stantially parallel, tosaid first bar and having a plurality of longitudinally spaced openings receiving said last named means. and. operable to rock said selected louvers beyond the position to which they are rocked by said first bar.

5. A fioor register adapted for connection with a forced air circulating system, comprising a frame having side and. end walls and defining an air outlet, a plurality of louvers-pivoted in said. frame on parallel axes and cooperating to substantially close said outlet in one position thereof, and an elongated shiftable bar having a plurality of longitudinally spaced openings, means carried by said louversspaced from, their pivot axes and extending intorsaid openings, some of said openings being elongated whereby movement of said bar partially rocks selQied louvers, and a second elongated independently shiftable bar substantially parallel to said first bar and having a plurality of longitudinally spaced openings receiving said last named means, at least some of the openings in said second bar being elongated and the elongated openings in both bars being of different lengths, the elongated openings in one bar having the ends nearest one end of said bar substantially equally spaced from each other and the elongated openings in the other bar having the ends nearest the opposite end. of said other bar substantially equally spacedfrom each other, the spacing of the equally spacedendsof both bars being substantially equal ta t e a i g of he B axe f h dj c t r s i s cond b rina r e at v o a d, se ected. louv s beyond the. pqs i a to which he ar v ro k bya fir t an Afl r; e t r antedc o w n ctio h forc d:- air circulating. system, comprising a frame having side andend walls and defining an. air outlet, a plurality of louvers, having legs substantially perpendicular thereto, at the ends thereof, means pivoting said louvers in said frame at the free ends of said. legs on parallel axes, extending lengthwise of and between theside edges of said louvers, said louvers, cooperating to substantially closesaid outlet in one position thereof, each louver being-cut away at a part of one end thereof, an elongated mem ber shiftableend-wise. in said frame adjacent one side and transversely of said lo uven pivot axes, and means, connecting said member to the louvers of a group: at points. spaced fromv the pivot axes of said louvers includ-. ing a lateral projection on each louver at said cutaway, at least one of, said connection means including an elongated slot extending lengthwise in said member and loosely receiving a pincarried by an end portion of one of; saidlateral projections to accommodate lost motion of said member relative to said louver, whereby each louver having such lost motion connection, is rotated through; a smaller angle than the remaining louvers as determined by the length of the associated slot uponactuation of said shiftable member.

7. A floor register as defined in claim 6, whereinsaid' frame; end walls flare oppositely upwardly andoutwardly, the louvers adjacent said end; walls being adapted to as: lim n: n in p i cn s b ant l c c din wi h the inclination of said end walls to deflect in endwise n pw rd: w air impinging t s d end ouvers 8, Afioor register as defined in claim 6, whereina, p lu rality of said louvers have slotted lost motion conne tion with said, member, said slotsbeing of different lengths whereby saidglouvers are tilted successively and through, differentangles by actuation of said shiftable member.

9;. A floor register adapted for connection with a forced; air; circulating system, comprising a frame hav-. ingside and end walls and defining an air outlet, a pluralit-yof louvers-pivoted insaid frame on parallel, axes and cooperating to substantially close said outlet in one position. thereof, each louver being cut away at apart of-anendthereof, and means withinsaid frame forrock-. ing a group of said louvers, said, means having lostmo-, tion connection with selected louvers of said group to partially actuate said selected louvers, anda second means Within said frame connected to andindependently rockv able for further, rocking the aforesaid selected louvers ofthesame group, said second means having lost motion; connections with at least some of the louvers connected thereto, said first and second louver-rocking means both being positioned between said frame and the cut away portions of, said louvers when said, louvers are in open position.

10. A floor register adapted for connection, with a forced air circulating system, comprising a frame having side and end walls and defining an air outlet, a plurality of louvers pivoted in said frame on parallel axes and cooperating to substantially close said outlet in one position thereof, and an elongated bar shiftable transversely of said axes and having a plurality of longitu dinally spaced openings, means carried by said louvers spaced'from their pivot axes and extendinginto said openings, some of. said openings being elongated whereby, movement of said bar partially actuates selected louvers, and a second independently shiftableelongated bar substantially parallel to said first bar and having aplurality of longitudinally spaced openings receiving said last namedmeans, at, least some of the openings in said second bar being elongated and the elongated openings in both bars being of different lengths and being arranged if rent rd r hs e a co d a Qk$; Q

lected louvers beyond the position to which they are rocked by said first bar.

11. A floor register adapted for connection with a forced air circulating system, comprising a frame having side and end walls and defining an air outlet, a plurality of louvers pivoted in said frame on parallel axes and cooperating to substantially close said outlet in one position thereof, and an elongated shiftable bar having a plurality of longitudinally spaced openings, means carried by said louvers spaced from their pivot axes and extending into said openings, some of said openings being elongated, whereby movement of said bar partially rocks selected louvers, and a second elongated independently shiftable bar substantially parallel to said first bar and having a plurality of longitudinally spaced openings receiving said last named means, at least some of the openings in said second bar being elongated and the elongated openings in both bars being of different lengths, the elongated openings in one bar having the ends thereof nearest one end of said bar substantially equally spaced 10 from each other and the elongated openings in the other bar having the ends thereof nearest the opposite end of said other bar substantially equally spaced from each other, said second bar being operative to rock said selected louvers beyond the position to which they are rocked by said first bar.

References Cited in the file of this patent UNITED STATES PATENTS 663,994 Kuhlman Dec. 18, 1900 680,657 Hart Aug. 13, 1901 1,737,946 Rood Dec. 3, 1929 1,858,289 Tracy May 17, 1932 2,090,908 Anderson Aug. 24, 1937 2,135,810 Germonprez Nov. 8, 1938 2,153,359 Anderson et al. Apr. 4, 1939 2,332,351 Serre Oct. 19, 1943 2,349,544 Fiedler May 23, 1944 2,473,053 De Roo June 14, 1949

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