US3680470A

US3680470A - Louver with a reduced turning radius

Info

Publication number: US3680470A
Application number: US81065A
Authority: US
Inventors: Roy M Neece
Original assignee: DYNAPLASTICS Inc
Current assignee: DYNAPLASTICS Inc
Priority date: 1970-10-15
Filing date: 1970-10-15
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01

Abstract

A louver having a frame and a set of vanes mounted for pivotal movement about axes of rotation characterized by a rack and pinion operating the vanes, the rack being affixed to a plurality of co-engaging members that snap together to encompass a horizontal vane in the louver to facilitate assembly. In another aspect, the louver is characterized by the vanes having pins, or stub shafts, disposed in notches along at least one side of the frame and a snap-on strip for that side of the frame to hold the vanes in place. Moreover, the vanes overlap so that they can completely block flow of a fluid through the louver. Specific structural features such as the protrusions of the snap-on strip engaging apertures in the frame, are also disclosed.

Description

United States Patent Neece [451 Aug. 1, 1972 [54] LOUVER WITH A REDUCED TURNING RADIUS I [72] Inventor: Roy M. Neece, Haltom City, Tex.

[73] Assignee: Dynaplastics, Inc., Ft. Worth, Tex.

[22] Filed: Oct. 15, 1970 21 Appl. No.: 8l,065

52 us. Cl ..9s/110, 49/77, 98/121 A [51] Int. Cl. ..F24f'13/00 [58] Field of Search..98/4O UM, 110,112, 114, 121; 137/601; 49/77, 78, 82, 88

[56] References Cited UNITED STATES PATENTS 3,552,295 l/l97l Armstrong .L ...98/l 10 3,388,655 6/1968 Dennis et a1 ..98/40 UM 2,940,375 6/1960 Schucker et a1. ..98/110 X 2,948,21 l 8/1960 Melgaard ..98/4O UM 3,035,504 5/1962 Cune fit 31.... ..98/110 X 3,472,149 10/1969 Harrison ...98/110X 3/1970 Dry ..98/1l0 3,572,233 3/1971 Bar et al ..49/77X Primary Examiner-William F. ODea Assistant Examiner-P. D. Ferguson Attorney-Woffard, Felsman & Fails [5 7] ABSTRACT A louver havinga frame and a set of vanes mounted for pivotal movement about axes of rotation characterized by a rack and pinion operating the vanes, the rack being affixed to a plurality of co-engaging members that snapv together to encompass a horizontal vane in the louver to facilitate assembly. In another aspect, the louver is characterized by the vanes having pins, or stub shafts, disposed in notches along at least one side of the frame and a snap-on strip for that side of the frame to hold the vanes in place. Moreover, the

vanes overlap so that they can completely block flow of a fluid through the louver. Specific structural features such as the protrusions of the snap-on strip engaging apertures in the frame; are also disclosed.

12 Claims, 5 Drawing Figures LOUVER WITH A REDUCED TURNING RADIUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to louvers such as are employed to effect a direction of flow of a fluid flowing therethrough.

2. Description of the Prior Art It is well known in the prior art to have a set of vanes formed integrally with the frame and a set of adjustable vanes. In this way, the vanes having a fixed relationship with the frame may be tilted as the frame is pivotally moved about its mounting means to effect a directional flow of fluid at an angle with respect to one plane such as a horizontal plane. The adjustable vanes are movable to effect the flow of the fluid at an angle with respect to a transverse plane. Individually adjustable vanes have been employed. Also, adjustable vanes having a protrusion to extend through the front of a louver frame are known. It is also known to employ a connector link at the rear of adjacent vanes to translate the movement of one of the vanes to the remainder of the vanes in a given row.

In general, the louvers of the prior art employed a multiplicity of elements such as screws and the like for assembly and were expensive to assemble. In special applications such as in automotive air conditioning systems, the louvers needed, but did not have, a small radius of rotation so as to be operable in a relatively small space. Moreover, the louvers did not ordinarily have the capability of blocking the flow of fluids therethrough and separate valves had to be installed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view from the front of a louver in accordance with one embodiment of this invention.

FIG. 2 is an isometric view from the rear of the louver ofFIG. 1.

FIG. 3 is an exploded isometric view of component parts of the louver of FIG. 1.

FIG. 4 is a simplified side view, partly in section, illustrating a central vane and operating mechanism and the radii of the louver of FIG. 1.

FIG. 5 is a top plan view of the vanes and operating mechanism of the louver of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENTS It is a primary object of this invention to provide a louver structure that alleviates the disadvantages of the prior art louvers.

The louver structure of this invention may be employed in effecting a direction of flow of any fluid. Ordinarily, it will be employed in directing the flow of a gas such as air in a conditioned air distribution system. It has particular utility in automotive air conditioning distribution systems where the space that is available for equipment is restricted. Accordingly, the following descriptive matter will be given with respect to the use of the louver in an automotive air conditioning equipment distribution system.

Referring to FIG. 1, louver 11 has a frame 13 and at least one vane 15 that is parallel with one of the major axes of the frame 13 and is connected with the frame. For example, the vane 15 may be substantially horizontal so as to effect a direction of air flow with respect to a horizontal plane as the frame 13 is tilted about its mounting means.

Louver 11 also has adjustable vanes 17 for effecting a desired flow of air with respect to another axis of the louver 11. For example, the adjustable vanes 17 may be mounted transversely to vane 15 for pivotal movement about their respective axes of rotation to effect a desired direction of air flow with respect to a vertical plane. The adjustable vanes 17 are mounted for pivotal movement about their axes of rotation by a pair of pin means such as pins, or stub shafts, 19, FIGS. 2 and 3. The pins 19 are located in notches 21 disposed along at least one side; and, preferably, on two opposite sides of the frame 13.

Control of the adjustable vanes is effected by a rack 23 and a pinion 25. The rack 23 is attached to one of a plurality of

co-engaging members

27 and 29. The

coengaging members

27 and 29 encompass the vane 15 such that the member 29 forms a slide bar means at the front of the louver. The co-engaging members are movable reciprocally and longitudinally of vane 15. They have mating fastening means such as respective mating protrusion means 31 and slot means 33 that may be disengageably snapped together to encompass the vane 15 and retain the rack in place. The vane 15 has limit means such as knobs 35, FIG. 5, for preventing movement of the rack 23 out of engagement with the pinion 25. Specifically, the vane 15 has an inner guide rail 37 that conformingly fits within a slot 39 of the inner member 27, FIG. 4, to facilitate longitudinal movement of the rack along vane 15. The inner guide rail 37 has knobs 35 located on either side of the region that will be traversed by the rack 23, FIG. 5. Thus, once correct correlative positioning of the rack and pinion is established, it is maintained until a new correlative position is established through disassembly and reassembly.

The pinion 25 is connected with one of the adjustable vanes 17; for example, the center vane so as to have its center aligned with the axis of rotation of the center vane 17a. With this construction, rotation of pinion 25 effects rotation, or pivotal movement, of the central vane 170 about its pair of pin means 19 in the notches 21. The pinion 25 engages the rack 23 such that the pinion 25 is rotated when the rack 23 is moved laterally. Consequently, the central vane 17a is moved pivotally by lateral movement of the rack 23. In my copending application entitled LOUVER AP- PARATUS, Ser. No. 32,115, filed Apr. 27, 1970, I described alternative structures in which the pinion 25 and central vane 170 may be (1) manufactured separately and appropriately connected together, or (2) injection molded together to form an integral structure. That descriptive matter is embodied herein by reference. As noted therein, the central vane 17a has a cut away portion 40. The cut away portion 40 allows the pinion 25 to have its center aligned with the axis of rotation, and engage rack 23, yet have central vane 17a large enough to overlap adjacent vanes for blocking flow.

While the

members

27 and 29, rack 23, and pinion 25 may be located at any point on the louver, it is preferable to locate them in the central portion to allow maximum flexibility in positioning the adjustable vanes 17.

As indicated hereinbefore, the adjustable vanes each have a pair of pin means such as upper and lower pins 19, FIG. 3, that are emplaced in upper and lower notches 21 for pivotal movement of the vanes. The notches 21 traverse from the inner edge 41 of frame 13 toward the front of the louver. A pair of snap-on

strips

43 and 45 are provided for retaining the pins 19 in the notches 21, once emplaced therein. The frame 13 has a plurality of separate first positions of holding means; such as, aperture means 47 disposed along its inner portion 49 adjacent the inner edge 41. The aperture means 47 will ordinarily penetrate completely through the side, since a complete aperture is readily molded;

but it is only necessary that the aperture means 47 comprise an appropriate indentation for receiving a mating protrusion means on the snap-on strips for retaining the snap-on strips in place. The snap-on

strips

43 and 45 have a plurality of mating separate second portions of holding means such as protrusion means 51 disposed at correlative intervals along their length. The protrusion means 51 are removably snapped into engagement with the aperture means 47 and conformingly engage the aperture means on at least two sides so as to be frictionally retained in place. The protrusion means are illustrated as having rectangular cross section. They may have any other cross section appropriate to the cross sectional shape of the aperture means 47. Any other mating separate first and second portions of holding means may be employed, but the respective aperture means and protrusion means form a preferred embodiment, since the lateral dimensions may be kept small to prevent enlarging the radii, R and R FIG. 4; and, consequently, the radius of rotation. The significance of a small radius of rotation is referred to hereinbefore and discussed in more detail hereinafter.

The snap-on

strips

43 and 45 also have protruding blocking means 53 disposed along their length in the notches 21 and retaining the set of adjustable vanes 17 in place. The snap-on strips have the protruding blocking means so positioned that the blocking means bear against the respective pin means 19 with sufficient forces to retain the adjustable vanes in any set position. Specifically, the arcuateinternal surface 55 of blocking means 53 bears frictionally against the respective pin means 19, forcing it frictionally into engagement with the inner arcuate portion of notch 21 so that the respective vane means are frictionally retained in any set position.

To enable the adjustable vanes 17 to be moved in unison to a respective set position, each vane has a third pin means 57, FIGS. .2 and 3, eccentrically disposed with respect to its axis of rotation. The third pin means 57 of the respective vanes are interconnected with each other via a connector link 59. The connector link 59 has a plurality of bifurcated ends 61 adapted for snapping over and for engaging the respective third pin means 57. The bifurcated ends 61 are disposed along the connector link 59 the same distance vanes 17 are disposed apart by respective pairs of pin means 19in notches 21. The third pin means 57 may be located at either the top or bottom of the adjustable vanes 17 or at any intermediate position. An opening, or second aperture means, 63 of a predetermined width sufficient to allow the bifurcated end 61 of the connector link 59 to move freely therewithin is provided around each respective third pin means 57, regardless of where it is positioned. In this way, interference between the respective adjustable vane 17 and the bifurcated end 61 is avoided, regardless of the angle at which the adjustable vane is disposed, or set.

In my copending application Ser. No. 32,1 15, referenced hereinbefore, there was described a plurality of types of mounting means; such as, apertures in the respective ends of frame 13 for receiving separate mounting pins, or shafts, and a mounting shaft 65 directly carried by the frame 13 at opposite ends to effect the desired pivotal mounting. That descriptive matter is incorporated herein by reference. Briefly, it described the use of a shaft of a plastic material for conformably fitting with contiguous parts such as an aperture-with sufficient frictional forces to retain the louver 11 in any set position, in terms of its angle with respect to a horizontal plane. A suitable plastic material comprises nylon or other suitable plastics delineated hereinafter.

If desired, the adjustable vanes 17 may have an identical structure such as typified by the central vane 17a. In this way, a single mold can be employed to form the respective vanes. Preferably, however, the exact structure of the central vane and the remainder of the vanes varies to effect overlap and enable blocking the flow of fluids therepast, as illustrated in FIG. 5. That is, the vanes 17 extend radially from their respective pin means 19 for a distance sufficient to overlap with the adjacent vane such that when moved into a closed position, they completely block the flow of fluids therepast, whereas center vane 17a has a cut away portion 40, described hereinbefore.

Despite the relatively long radial distance the vanes 17 extend, it is desirable that the louver have a small radius of rotation and small radii, R and R referred to hereinbefore and illustrated in FIG. 4. Accordingly, the upper and lower pin means 19 and the third pin means 57 with its attached connector link 59, are so positioned as to form a minimal radius R The illustrated louver construction enables forming a louver that can be rotated, or pivoted, within an opening having a radius less than one inch radius of rotation. Such a preferred compact structure is particularly advantageous in automotive air conditioning distribution systems.

The assembly and operation of the louver may be understood by referring to FIG. 3. Therein, pinion 25 in emplaced on central vane 17a is not already integrally formed therewith. The

co-engaging members

27 and 29 are emplaced about vane 15 intermediate the limit knobs 35, andtheir mating fastening means 31 and 33 snapped together. The rack and pinion are then correlatively positioned in accordance with the position-of the central vane 17a as its pin means 19 are inserted into its respective notch 21. For example, the central vane 17a may be disposed substantially perpendicular, or normal, to vane 15 when the rack 23 is disposed at about the midpoint of the vane 15. On the other hand, the correlative positioning may be with the adjustable vanes in a closed position as illustrated in FIG. 5 and the rack positioned at its extreme position toward that end, abutting the respective knob 35 on vane 15. The remainder of the adjustable vanes 17 are emplaced by their respective upper and lower pins 19 being inserted into their respective notches 21. The snap-on

strips

43 and 45 are snapped into position with the respective first and second portions of holding means co-engaging. Their blocking means 53 are disposed in the respective notches 21 and engage the respective pin means 19, as described hereinbefore. Thus, the vanes are retained in place in the frame 13.

The respective adjustable vanes 17 are positioned at about the same angle and the bifurcated ends 61 of the connector link 59 are snapped into place about the respective third pin means 57 at the rear of the respective adjustable vanes 17, as illustrated in FIG. 2.

After louver 11 is assembled, it is mounted in its appropriate aperture or plenum by appropriate mounting means and suitable bezel. Suitable bezel structures facilitating assembly of the louvers are described in copending applications entitled BEZEL LOUVER SUPPORT STRUCTURE, Inventor Frank S. Dennis, Ser. No. 66,362, filed Aug. 24, 1970, and now US. Pat. No. 3,641,913; and BEZEL INNER GUIDE FRAME, Inventor Randall W. Johnson, Ser. No. 66,221, filed Aug. 24, l970; both assigned to the assignee of this invention. The particular snap-on structure described therein is appropriate to the use of mounting shafts such as mounting shaft 65 illustrated herein.

Once emplaced, the desired direction of flow of conditioned air is effected by simply tilting louver 1 1 about its respective mounting means 65 to effect the desired angle via vane 15 and frame 31; by moving slide bar 29 and, consequently, rack 23 to effect the desired angle of pivot of the adjustable vanes 17; or both.

In the manufacturing of the louver or constituents thereof, any appropriate materials of construction may be employed. It is preferable, however, to employ corrosion resistant materials when certain fluids flow therepast and, by one process or another, induce corrosion between contiguous elements of the louver. For example, cold air cools the elements of the louver and causes a condensation of moisture between contiguous elements. Where these elements are constructed of metal that corrodes in such an environment, there is a reaction such as rusting that impedes free operability of the respective elements. Any corrosion resistant material may be employed depending upon the nature of the gas flowing therepast. Either a thermosetting plastic material or a thermoplastic material may be employed as long as it has a sufiiciently high melting point and resists deformation such as warping. Typical of satisfactory thermosetting plastic materials are the phenol-formaldehyde copolymers and the melamineformaldehyde copolymers.- Typical of satisfactory thermoplastic materials are the acrylonitrile-butadienestyrene copolymers, commonly referred to as ABS, and the polycarbonate plastic. Appearance and customer satisfaction is improved if the plastic elements that are exposed to view are coated with a thin coating of decorative metal such as aluminum.

The respective pin means may be formed separately and connected with the respective vanes if desired. Preferably, however, the pin means are integrally formed with the vanes as illustrated in the respective figures. A particularly preferred structure is effected when both vanes and pin means are formed of the indicated plastic as by injection molding, since in this way the proper positioning of the pins of the vanes is effected with no problems in assembly.

Thus, it can be seen that the invention provides an improved louver structure that alleviates the disadvantages of the prior art louvers. Specifically, the invention provides a louver structure wherein the elements may be snapped into position, without employing bolts, screws or additional tools such as screw drivers, pliers and the like, to facilitate and economize assembly. That is, the rack is readily snapped into place about horizontal vane 15, the adjustable vanes inserted in notches and the snap-on strips snapped into place to retain them there. Additionally, the invention provides a louver that has the snap-on strips contributing minimally to the dimensions of the louver such that a very small radius of rotation is effected, yet that has vanes that overlap to enable completely blocking the flow of fluid therepast.

Although the invention has been described with a certain degree of particularlity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

What is claimed is:

1. In a louver having a frame and a set of vanes mounted for pivotal movement about respective axes of rotation and engaging oppositely disposed sides of said frame, the improvement comprising:

a. a normal vane carried in the front of said frame, fixedly connected to said frame, and disposed at an angle that is substantially normal with respect to said axes of rotation; said normal vane defining a fixed, substantially lineal track for movement of a rack therealong;

. a plurality of co-engaging members encompassing said normal vane and including an exterior member that forms a slide bar means at the front of said louver and an interior member that carries a lineal rack; said co-engaging members being movable reciprocally and longitudinally of said normal vane by movement of said slide bar means such that said rack is operable from the front of said louver; said co-engaging members having mating fastening means reversibly engaging each other, said mating fastening means comprising structure that can be disengagably snapped together to facilitate assembly and disassembly;

. a pinion connected with one of said vanes so as to have its center aligned with said axis of rotation of said one of said vanes whereby rotation of said pinion effects rotation of said vane, said pinion engaging said rack such that lateral movement of said rack longitudinally of said normal vane effects rotation of said pinion;

a pin means connected with each vane of said set of vanes, eccentric with respect to said axis of rotation thereof, and an aperture means of a predetermined width surrounding said pin means; and

e. a connector link having a plurality of bifurcated ends removably snapped over and engaging respective said pins and interconnecting said vanes of said set of vanes with each other via said pin means, said bifurcated ends being adapted to move within said aperture means and being disposed along said connector link the same distance said vanes are disposed apart by respective means defining said axes of rotation.

2. The louver of claim 1 wherein said co-engaging members have respective mating protrusion means and slot means that may be disengagably snapped together to encompass said normal vane and retain said rack in place.

3. The louver of claim 1 wherein said rack is integrally formed with an interior one of said plurality of co-engaging members.

4. The louver of claim 1 wherein said normal vane has limit means for preventing movement of said rack out of engagement with said pinion.

5. The louver of claim 1 wherein said pinion is integrally formed with said one of said vanes.

6. The louver of claim 1 wherein said pinion is formed with a slot means therein for conformingly engaging said one of said vanes, said one vane has a cut away portion for receiving said pinion, and said pinion and said one of said vanes are assembled after manufacture.

7. The louver of claim 1 wherein elements of said louver are formed of acrylonitrile-butadiene-styrene copolymer.

8. The louver of claim 1 wherein said vanes in said set of vanes extend on both sides of said respective axes of rotation so as to enable blocking the flow of a fluid through said louver when said vanes are closed.

9. The louver of claim 1 having a small radius of rotation, wherein said means defining said axes of rotation are located in notches disposed along at least one side of said louver frame, said notches being open toward the inner edge of said louver frame and wherein there is provided:

a. a plurality of separate first portions of holding means disposed along the inner edge of said at least one side of said louver frame for retaining a strip in place; and

b. a snap-on strip disposed along said at least one side and bearing against said respective means defining said axes of rotation; said snap-on strip having interiorly protruding blocking means disposed along its length in said notches and retaining said vanes of said set of vanes in place; said snap-on strip having a plurality of mating separate second portions of holding means disengagably snapped into engagement with said first portions of holding means; said first and second portions of holding means comprising a plurality of respective aperture means for receiving protrusions snapped thereinto and protrusion means for conformingly and frictionally engaging said aperture means on at least two sides thereof; said aperture means and said protrusion means being disposed at correlative intervals along the lengths of said snap-on strip and said at least one side of said louver frame such that said protrusion means can be snapped into said aperture means and hold said snap-on strip positively against lateral and longitudinal movement, and yet allow radial movement against only snapo osi el dis osed ends thereof for, ivot mountin ar i said ram has a radius of rotatign of less than inch about said mounting means, said radius of rotation being measured from the axis of said mounting means to the extremities of said louver in a direction perpendicular to said axis.

11. In a louver having a small radius of rotation and having a frame and a set of vanes mounted for pivotal movement about respective means defining axes of rotation and located in notches disposed along two oppositely disposed sides of the louver frame, the notches being open toward the inner edge of said louver frame, the improvement comprising:

a. a plurality of separate first portions of holding means disposed along an inner portion adjacent the inner edge of each of said sides of said louver frame for retaining a strip in place; and

b. a snap-on strip disposed along each of said sides and bearing against said respective means defining said axes of rotation; said snap-on strip having interiorly protruding blocking means disposed along its length in said notches and retaining said vanes of said set of vanes in place; each snap-on strip having a plurality of mating separate second portions of holding means disengagably snapped into engagement with first portions of holding means; said first and second portions of holding means comprising a plurality of respective aperture means for receiving protrusions snapped thereinto and protrusion means for conformingly and frictionally engaging said aperture means on at least two sides thereof; said aperture means and said protrusion means being disposed at correlative intervals along the length of said sides and said snapon strip such that said protrusion means can be snapped into said aperture means and hold said snap-on strip positively against lateral and longitudinal movement, and yet allow radial movement against only snap-in friction such that said snap-on strip is readily removable to facilitate disassembly and readily snapped into place to facilitate assembly.

12. The louver of claim 11 wherein said frame has as said first portion of said holding means a plurality of longitudinally extending aperture means and a plurality of laterally extending aperture means disposed along its length and conformingly engaging mating protrusion means on said snap-on strip and wherein said snap-on strip bears against said means defining said axes of rotation with sufficient force to retain said vanes in any set position.

Claims

1. In a louver having a frame and a set of vanes mounted for pivotal movement about respective axes of rotation and engaging oppositely disposed sides of said frame, the improvement comprising: a. a normal vane carried in the front of said frame, fixedly connected to said frame, and disposed at an angle that is substantially normal with respect to said axes of rotation; said normal vane defining a fixed, substantially lineal track for movement of a rAck therealong; b. a plurality of co-engaging members encompassing said normal vane and including an exterior member that forms a slide bar means at the front of said louver and an interior member that carries a lineal rack; said co-engaging members being movable reciprocally and longitudinally of said normal vane by movement of said slide bar means such that said rack is operable from the front of said louver; said co-engaging members having mating fastening means reversibly engaging each other, said mating fastening means comprising structure that can be disengagably snapped together to facilitate assembly and disassembly; c. a pinion connected with one of said vanes so as to have its center aligned with said axis of rotation of said one of said vanes whereby rotation of said pinion effects rotation of said vane, said pinion engaging said rack such that lateral movement of said rack longitudinally of said normal vane effects rotation of said pinion; d. a pin means connected with each vane of said set of vanes, eccentric with respect to said axis of rotation thereof, and an aperture means of a predetermined width surrounding said pin means; and e. a connector link having a plurality of bifurcated ends removably snapped over and engaging respective said pins and interconnecting said vanes of said set of vanes with each other via said pin means, said bifurcated ends being adapted to move within said aperture means and being disposed along said connector link the same distance said vanes are disposed apart by respective means defining said axes of rotation.

9. The louver of claim 1 having a small radius of rotation, wherein said means defining said axes of rotation are located in notches disposed along at least one side of said louver frame, said notches being open toward the inner edge of said louver frame and wherein there is provided: a. a plurality of separate first portions of holding means disposed along the inner edge of said at least one side of said louver frame for retaining a strip in place; and b. a snap-on strip disposed along said at least one side and bearing against said respective means defining said axes of rotation; said snap-on strip having interiorly protruding blocking means disposed along its length in said notches and retaining said vanes of said set of vanes in place; said snap-on strip having a plurality of mating separate second portions of holding means disengagably snapped into engagement with said first portions of holding means; said first and second portions of holding means comprising a plurality of respective aperture means for receiving protrusions snapped thereinto and protrusion means for conformingly and frictionally engaging said aperture means on at least two sides thereof; said aperture means and said protrusion means being dispOsed at correlative intervals along the lengths of said snap-on strip and said at least one side of said louver frame such that said protrusion means can be snapped into said aperture means and hold said snap-on strip positively against lateral and longitudinal movement, and yet allow radial movement against only snap-in friction such that said snap-on strip is readily removable to facilitate disassembly and readily snapped into place to facilitate assembly.

10. The louver of claim 9 wherein said snap-on strip bears against said means defining said axes of rotation with sufficient force to retain said vanes in any set position; and wherein said frame carries mounting means at oppositely disposed ends thereof for pivotal mounting and said frame has a radius of rotation of less than 1 inch about said mounting means, said radius of rotation being measured from the axis of said mounting means to the extremities of said louver in a direction perpendicular to said axis.

11. In a louver having a small radius of rotation and having a frame and a set of vanes mounted for pivotal movement about respective means defining axes of rotation and located in notches disposed along two oppositely disposed sides of the louver frame, the notches being open toward the inner edge of said louver frame, the improvement comprising: a. a plurality of separate first portions of holding means disposed along an inner portion adjacent the inner edge of each of said sides of said louver frame for retaining a strip in place; and b. a snap-on strip disposed along each of said sides and bearing against said respective means defining said axes of rotation; said snap-on strip having interiorly protruding blocking means disposed along its length in said notches and retaining said vanes of said set of vanes in place; each snap-on strip having a plurality of mating separate second portions of holding means disengagably snapped into engagement with first portions of holding means; said first and second portions of holding means comprising a plurality of respective aperture means for receiving protrusions snapped thereinto and protrusion means for conformingly and frictionally engaging said aperture means on at least two sides thereof; said aperture means and said protrusion means being disposed at correlative intervals along the length of said sides and said snap-on strip such that said protrusion means can be snapped into said aperture means and hold said snap-on strip positively against lateral and longitudinal movement, and yet allow radial movement against only snap-in friction such that said snap-on strip is readily removable to facilitate disassembly and readily snapped into place to facilitate assembly.