Roller clutch

A roller clutch for a window shade includes a housing, a bead chain wheel, and a roller adapter. Transmission of movement from the bead chain to the roller adapter depends upon the force applied by the bead chain to the roller clutch.

FIELD OF THE INVENTION

The present disclosure relates a window shade. More particularly, to a clutch for a window shade roller.

BACKGROUND OF THE INVENTION

Window shades are typically provided to block sun light from passing into a room through a window or other architectural opening and for privacy. Some window shades have rollers upon which fabric is wound. Roller clutches may be provided to control the winding and/or unwinding of the fabric wound on the roller of the window shade.

According to one aspect of the present disclosure, a roller clutch for a window shade including a housing, a bead chain wheel supported by the housing and configured to receive a bead chain, a roller adapter sized to be received within a window shade roller, and interactive members having a first state transmitting bead chain movement from the bead chain wheel to the roller adapter to rotate the window shade roller and a second state blocking transmission of the bead chain movement from the bead chain wheel to the roller adapter while permitting rotation of the bead chain wheel.

According to another aspect of the present disclosure, an roller clutch for a window shade is provided including a housing, a unitary bead chain wheel supported by the housing and configured to receive a bead chain, a roller adapter sized to be received within a window shade roller, and interactive members having a first state transmitting bead chain movement from the bead chain wheel to the roller adapter to rotate the window shade roller and a second state blocking transmission of the bead chain movement from the bead chain wheel to the roller adapter.

According to another aspect of the present disclosure, a roller clutch for a window shade is provided including a housing, a bead chain wheel supported by the housing and configured to receive a bead chain, a roller adapter sized to be received within a window shade roller, and a spring positioned outside of the bead chain wheel to urge the roller clutch to a disengaged position blocking transmission of movement of the bead chain to the roller adapter. Force from the bead chain moves the roller clutch to an engaged position transmitting movement of the bead chain to the roller adapter to rotate the window shade roller.

According to another aspect of the present disclosure, a roller clutch for a window shade is provided including a housing and a bead chain wheel supported by the housing and configured to receive a bead chain. The bead chain wheel is moveable relative to the housing from a raised position to a lowered position. The bead chain wheel has an upper portion and a lower portion. The lower portion of the bead chain wheel moves relative to the housing during movement of the bead chain wheel between the raised and lowered positions. The roller clutch further includes a roller adapter sized to be received within a window shade roller. Transmission of movement of the bead chain to the roller adapter is dependent upon movement of the bead chain wheel between the raised and lowered positions.

According to another aspect of the present disclosure, n roller clutch for a window shade is provided including a housing and a bead chain wheel supported by the housing and configured to receive a bead chain. The bead chain wheel has an axis of rotation moveable relative to the housing from a first position to a second position. The roller clutch further includes a roller adapter sized to be received within a window shade roller. Transmission of movement of the bead chain to the roller adapter is dependent upon movement of the axis of rotation of the bead chain wheel.

According to another aspect of the present disclosure, a roller clutch for a window shade is provided including a housing, a bead chain wheel supported by the housing and configured to receive a bead chain, a roller adapter sized to be received within a window shade roller, and interactive members having a first state transmitting bead chain movement from the bead chain wheel to the roller adapter to rotate the window shade roller and a second state blocking transmission of the bead chain movement from the bead chain wheel to the roller adapter. The size of the bead chain wheel remains consistent during movement of the interactive members between the first and second states.

Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings.

According to the present disclosure, a window shade10is provided that includes a roller tube14, fabric16wrapped on roller tube14, roller clutch18coupled to roller tube14, bead chain20coupled to roller clutch18, and a tensioner22applying tension to bead chain20. One end of roller tube14is typically supported by roller clutch18in a window opening24and the other end by an idler26that provide rotational support of the ends of roller tube14. Roller clutch18may be supported in window24opening by a separate bracket (not shown) or integrated with a bracket or otherwise configured to be supported in window opening24. Window shade10may be positioned directly within window opening24, adjacent to window opening24, above window opening24or otherwise to block sunlight and/or air flow through window opening24.

Normally, fabric16of window shade10is stationary in one of a fully raised position allowing more light to pass through window opening24into a room, a fully lowered position allowing less or none of the light to pass through window opening24into the room, or in an intermediate position between the fully raised and lowered positions. To change the position of fabric16, a user pulls either side of bead chain20up or down to roll or unroll fabric16from roller tube14.

Bead chain20is the preferred embodiment of a continuous loop actuator that extends between tensioner22and roller clutch18. According to alternative embodiments, the actuator may be unbeaded, such as a cord, non-continuous, such as having one or more terminal ends, or other suitable actuator configurations known to those of ordinary skill in the art.

According to the preferred embodiment of the present disclosure, force and/or energy transmitted through bead chain20will not raise or lower fabric16unless a lower end28of bead chain20is fixed to window opening24or another structure. If lower end28of bead chain20is properly fixed, roller clutch18transmits the force and/or energy to roller tube14to raise or lower fabric16.

According to the preferred embodiment of the present disclosure, roller clutch18is configured to detect when tension is applied to bead chain20providing an indication that lower end28of bead chain20is properly fixed. Tensioner22couples bead chain20to window opening24or other building structure. After installation, tensioner22applies a downward force on bead chain20, which applies tension to bead chain20. Preferably, roller clutch18detects this tension and allows the force and/or energy applied by a user to bead chain20to rotate roller tube14to raise or lower fabric16.

Referring toFIG. 2, an example window shade mount/roller clutch110is shown having a support end or bracket112mounted on a portion of window opening24, a first engagement portion114coupled to bead chain20, a second engagement portion116, and a roller support end118supporting roller14. Portions of roller clutch110may positioned within roller14and portions may be positioned outside of roller14.

First and second engagement portions114,116are positioned relative to each other to transmit force provided by bed chain20to roller14to raise or lower fabric16supported by roller14. When lower end28of bead chain20is coupled to wall opening24, as shown inFIG. 2, first engagement portion114engages or otherwise enables the transfer of force and/or energy from bead chain20to second engagement portion116. If lower end28of bead chain20is not coupled to wall opening24or another portion of a building structure, first engagement portion114blocks the transfer of force and/or energy to second engagement portion116by disengaging from second engagement portion116or otherwise preventing the force and/or energy from bead chain20to roller14.

Referring toFIG. 3A, a roller clutch210is shown having first engagement portion214spaced apart from second engagement portion216so that force transmitted by bed chain20is not transmitted to second engagement portion216so the force and/or energy provided by bed chain20does not raise or lower fabric16supported by roller14. A housing218(shown in phantom), supports second engagement portion216relative to first engagement portion214. First engagement portion216is spaced apart from second engagement portion216because lower end28of bead chain20is not secured to window opening24. Because first and second engagement portions214,216are spaced apart, force and/or energy transferred to first engagement portion214is not transferred to second engagement portion216and roller14is not raised or lowered.

When lower end28of bead chain20is fastened to window opening24or otherwise, first engagement portion214moves into engagement with second engagement portion216as shown inFIG. 3B. When sufficiently engaged with each other, first engagement portion214will rotate second engagement portion216, causing roller14to rotate to raise or lower fabric16. This engagement allows force/energy transmitted to first engagement portion214from bead chain20to be transmitted to second engagement portion216. Preferably, the direction of rotation of first engagement portion214depends on which side of bead chain20the user pulls.

The movement of first engagement portion214is shown as horizontal inFIG. 3A, but it could be in other directions, such as vertical. Furthermore, first engagement portion214is shown moving inFIG. 3Ato provide the engagement and disengagement. According to alternative embodiments, the movement may occur in other components, such as second engagement portion216or otherwise.

Although shown as completely separated inFIG. 3A, first and second engagement portions214,216may be in contact or partial engagement and still not transmit sufficient force and/or energy from bead chain20to roller14. For example, when bead chain20is properly secured, first and second engagement portions214,216may be engaged with a first amount of force between them that is sufficient to transmit force/energy from bead chain20. When bead chain20is not properly secured, first and second engagement portions214,216may be engaged by a second amount of force. The second amount of force may allow slippage between first and second engagement portions214,216so that roller14does not raise or lower fabric16.

Referring toFIG. 4A, a roller clutch310is shown having first engagement portion314engaged with blocking member312and in contact with second engagement portion316. Blocking member312prevents rotation of first engagement portion314that receives force and/or energy from bead chain20. Because blocking member312prevents such rotation, force/or energy transmitted by bed chain20is not transmitted to second engagement portion316so the force and/or energy provided by bed chain20does not raise or lower fabric16supported by roller14. First engagement portion314is engaged with blocking member312because the lower end of bead chain20is not secured to window opening24.

When bead chain20is fastened to window opening24or otherwise, first engagement portion314moves out of engagement with blocking member312as shown inFIG. 4B. This disengagement allows force/energy transmitted to first engagement portion314from bead chain20to be transmitted to second engagement portion316because first engagement portion314can rotate or otherwise move. When sufficiently disengaged from blocking member312, first engagement portion314will rotate second engagement portion316, causing roller14to rotate to raise or lower fabric16.

The movement of first engagement portion314is shown as horizontal inFIG. 4A, but it could be in other directions, such as vertical. Furthermore, first engagement portion314is shown moving inFIG. 4Ato provide the engagement and disengagement. According to alternative embodiments, the movement may occur in other components, such as in blocking member312, second engagement portion316, or otherwise. First and second engagement portions314,316may be splined together or otherwise coupled together to permit translation therebetween as shown inFIGS. 4A and 4Bwhile coupling them together for rotation.

Although shown as completely separated from blocking member312inFIG. 4A, first second engagement portion314may be in contact or partial engagement with blocking member312and still transmit sufficient force and/or energy from bead chain20to roller14. For example, when bead chain20is properly secured, first engagement portion314and blocking member312may be engaged with a first amount of force between them. When bead chain20is not properly secured, first engagement portion314and blocking member312may be engaged by a second amount of force. The first amount of force may allow slippage between first engagement portion314and blocking member312so that roller14raises or lowers fabric16.

FIGS. 5A and 5Billustrate a roller clutch410having a housing412, a first engagement portion414shaped as a first gear and a second engagement portion416shaped as a second gear positioned radially inwardly of the first gear414. First gear414supports bead chain20and receives force and/or energy from bead chain20. As shown inFIG. 5A, first gear414is spaced apart from second gear416so that the teeth of gears414,416to not engage by meshing. A device, such as a spring (not shown) biases first gear414to the position shown inFIG. 5Awhen bead chain20is not coupled to window opening24or other structure with sufficient tension to overcome the bias of the spring. When bead chain20is coupled to window opening24and tensioned with sufficient force, bead chain20pulls first gear414downward toward second gear416against the bias of the spring as shown inFIG. 5B. This movement engages the teeth of gears414,416by meshing.

When in the position shown inFIG. 5A, bead chain20can rotate first gear414. Because the teeth of first and second gears414,416are not engaged, the rotation of the first gear is not transmitted to the second gear416. Thus, even though first gear414rotates, second gear416does not. Preferably, second gear416is operatively coupled to roller14so that rotation of second gear416rotates roller14to raise or lower fabric16as shown inFIG. 5B. Thus, when bead chain20is properly coupled to window opening24, bead chain20will rotate first and second gears414,416and roller14in either direction depending on which side of bead chain20the user pulls.

FIGS. 6A and 6Billustrate a roller clutch510having a housing512, a first engagement portion514shaped as gear teeth in housing512and a second engagement portion516shaped as a gear positioned below gear teeth514. Gear516supports bead chain20and receives force and/or energy from bead chain20. As shown inFIG. 6A, gear414is engaged with gear teeth514of housing512to block rotation of gear516. A device, such as a spring (not shown) biases gear516to the position shown inFIG. 6Awhen bead chain20is not coupled to window opening24or other structure with sufficient tension to overcome the bias of the spring. When in the position shown inFIG. 6A, bead chain20cannot rotate gear516. Because teeth514and the teeth of gear516are engaged, the force and/or energy of bead chain20is not transmitted to roller14. When bead chain20is coupled to window opening24and tensioned with sufficient force, bead chain20pulls gear516downward against the bias of the spring as shown inFIG. 6B. This movement disengages teeth of gear516from teeth514to allow rotation of gear516.

Preferably, gear516is operatively coupled to roller14so that rotation of gear516rotates roller14to raise or lower fabric16as shown inFIG. 6B. Thus, when bead chain20is properly coupled to window opening24, bead chain20will rotate gear516and roller14in either direction depending on which side of bead chain20the user pulls.

FIGS. 7A and 7Billustrate a roller clutch610having a base or housing612(portions shown in phantom), a first engagement portion or bead chain wheel614having teeth or lugs and a second engagement portion616having teeth or lugs positioned between roller14and first engagement portion614. First engagement portion614supports bead chain20and receives force and/or energy from bead chain20. As shown inFIG. 7A, first engagement portion614is spaced apart from second engagement portion616so that the teeth or lugs do not mesh to prevent rotation of first engagement portion514by bead chain20from rotating second engagement portion616and roller14. First engagement portion616rotates on a shaft622that rides up and down housing612. A device, such as a spring (not shown), biases first engagement portion614to the position shown inFIG. 7Awhen bead chain20is not coupled to window opening24or other structure with sufficient tension to overcome the bias of the spring. When bead chain20is coupled to window opening24and tensioned with sufficient force, bead chain20pulls first engagement portion616downward against the bias of the spring as shown inFIG. 7B. Housing612includes a ramp618and first engagement portion614includes a corresponding annular ramp620. As bead chain20pulls first engagement portion616down, ramp618urges first engagement portion614to the right as shown in FIG.7B. This movement engages the teeth of first engagement portion614with the teeth of the second engagement portion616to allow rotation of second engagement portion616. Also during this movement, the axis of rotation of first engagement portion614moves axially relative to its axis of rotation.

When in the position shown inFIG. 7A, bead chain20cannot rotate second engagement portion616. Because first and second engagement portions614,616are disengaged, the force and/or energy of bead chain20is not transmitted to roller14. Preferably, second engagement portion616is operatively coupled to roller14so that rotation of second engagement portion616rotates roller14to raise or lower fabric16as shown inFIG. 7B. Thus, when bead chain20is properly coupled to window opening24, bead chain20will rotate second engagement portion616and roller14in either direction depending on which side of bead chain20the user pulls.

According to one alternative embodiment, the teeth and lugs of engagement portions614,616are replaced with friction plates that engage and disengaged as described above. When bead chain20is tensioned, eventually enough force exists between first and second engagement portions614,616to transmit sufficient force and/or energy to second engagement portion616to rotate roller14.

According to another alternative embodiment, housing612includes one or more blocking members (not shown) similar to the teeth of first engagement portion614. These blocking members are positioned between first engagement portion614and the left portion of housing612. The teeth of first engagement portion614are moved to the opposite side of first engagement portion614from that shown inFIGS. 7A and 7Bto engage or mesh with the blocking member(s) of housing612. First and second engagement members612,614are coupled together to permit translation therebetween and remain coupled together against relative rotation. If bead chain20is not coupled to window opening24, the blocking members of housing612engage the corresponding teeth of first engagement portion614to block rotation thereof. If bead chain20is coupled to window opening24and pulls first engagement portion614down (as shown illustratively inFIG. 7B), the blocking members of housing612disengages from the teeth of first engagement portion614to allow rotation of first engagement portion614, second engagement portion616, and roller14.

A preferred embodiment roller clutch710is shown inFIGS. 8A-17F. Roller clutch710includes a housing712, a plurality of wrap springs714, a first engagement portion716formed as ring716providing a combination bead chain wheel718and first gear720, a second engagement portion722formed as clutch spring driver724and second gear726, a roller or drive adapter728, a gear separator730, and a pair of springs732. Typically, roller clutch710is supported on a metal bracket (not shown) which is mounted in window opening24. Additional details of a suitable bracket are provided in U.S. Pat. No. 6,935,401, to Fraczek et al., the entire disclosure of which is expressly incorporated by reference herein. According to an alternative embodiment, the metal bracket is permanently attached to the housing to reduce the overall length of the roller clutch and bracket combination and reduce the number of parts an installer must handle. Roller14is inserted over drive adapter728to rotate roller14.

Bead chain wheel718is preferably unitary. For example, an upper portion is integral with a lower portion. During movement of chain wheel718as discussed below, the portions of bead chain wheel718move in unison.

When assembled, springs714are positioned over a cylinder734of housing712. Springs714include coils736and a plurality of tangs738. Before assembly, coils736have an inner diameter that is slightly smaller than the outer diameter of cylinder734. To assemble springs714on cylinder734, springs714are expanded so they will fit over cylinder734. When released from this expanded, assembly condition, coils736grip the exterior of cylinder734to create friction therebetween. This friction resists rotation of springs714on cylinder734. As described below in greater detail, springs714interact with drive adapter728to either rotate roller14or block rotation of roller14. When springs714sufficiently grip cylinder734, the interaction between drive adapter728and springs714blocks rotation of roller14.

During normal operation, bead chain20extends over chain wheel718, which transmits rotational force or torque to clutch spring driver724when a user pulls on either side of bead chain20and bead chain20is properly installed. Clutch spring driver724includes a pair of windows740at least partially defined by a pair of drive surfaces742. Tangs738of springs714extend into windows740. When bead chain20and chain wheel718rotate clutch spring driver724, one of drive surfaces742contact tangs738to slightly expand coils736. This expansion reduces the grip of coils736on cylinder734and the friction therebetween to allow springs714to rotate on cylinder734. As discussed above, drive adapter728will rotate with springs714to rotate roller14and raise or lower fabric16.

The weight of fabric16on roller14creates rotational force or torque. As shown inFIGS. 18A-18E, drive adapter728includes a pair of inwardly extending lugs744. Unless a user is pulling on bead chain20, one of lugs744presses on one set of respective tangs738of springs714. This force encourages springs714to retract further toward cylinder734, which increases the grip between springs714and cylinder734to further block rotation of springs714on cylinder734. Additional details of suitable clutch spring operation are provided in U.S. Pat. No. 4,372,432, to Waine et al and U.S. Pat. No. 5,375,643; to Rude, the entire disclosures of which are expressly incorporated by reference herein.

As discussed above, in normal operation when lower end28of bead chain20is coupled to window opening24, bead chain20operates clutch710to raise and lower fabric16on roller14. However, if lower end28of bead chain20is not coupled to a window opening24or otherwise adequately secured, bead chain20will not operate clutch710to raise or lower fabric16.

As discussed above, force and/or energy are transmitted from bead chain20through the combination chain wheel718and first gear720, the combination second gear726and clutch spring driver724, and drive adapter728to roller14. Because respective tangs738of springs714are sandwiched between clutch spring driver724and drive adapter728, they also transmit this force and/or energy. The transmission of force and/or energy between first gear720and second726is dependent on whether lower end28of bead chain20is adequately secured or not. If bead chain20is not adequately secured, little or no transmission of force and/or energy is transmitted between first and second gears720,726so that bead chain20will not raise or lower fabric16.

As shown inFIGS. 12, 13A, and 13B, first gear720includes a plurality of interactive members or internal gear teeth746and second gear726includes a plurality of interactive members or external teeth748that mesh with teeth746during a first state or normal operation when bead chain20is secured to window opening24. As a result of this meshing, first gear720rotates second gear726as a user pulls on either side of bead chain20. The resulting rotation of second gear726rotates spring driver724, springs714that have been relaxed, drive adapter728, and roller14.

As shown inFIGS. 10 and 11, gear separator730has a bearing surface that contacts an inner bearing surface750of ring716. This contact biases ring716upward relative to housing712. During assembly, lower ends754of gear separator730are inserted through openings755in housing712as shown inFIG. 8B. Upper ends of springs732are positioned within apertures or spring seats752on ends754of gear separator730and lower ends of springs734are positioned within apertures or spring seats756of ledges758of housing712. When positioned between spring seats752,756, springs732are positioned outside of housing712and bead chain wheel718and bias gear separator730in an upward direction relative to housing712which biases ring716in the upward direction relative to housing712.

When properly coupled to window opening24, bead chain20biases ring716downward in a direction opposite of the bias of gear separator730as shown inFIG. 11. If lower end28of bead chain20is not properly coupled to window opening24, gear separator730urges ring716with first gear720upward away from second gear726as shown inFIG. 10. This movement to a second state separates internal gear teeth746of first gear720from external gear teeth748of second gear726, as shown inFIG. 12, so that rotation of ring716by bead chain20is not transmitted to roller14. Thus, when bead chain20is not properly coupled to window opening24, bead chain20will not rotate roller14to raise or lower fabric16to disable clutch710. Similarly, if tensioner22is uncoupled, removed or the tension in bead chain20is otherwise removed, gear separator730will push first gear720upward and disable clutch710.

Even though bead chain20cannot rotate roller14, it can rotate bead chain ring716. Thus, if bead chain20is not properly coupled to window opening24, a user pulling on either side of bead chain20can cause chain ring716to rotate and bead chain20to rotate about bead chain ring716. Thus, even though a user pulls down on either side of bead chain20to translate that side down while the other side translates up, roller14does not rotate.

Because gear separator730is always exerting upward force on chain ring716, little or no rotational movement of bead chain20is required to move first gear720of chain ring716out of engagement with second gear726when lower end28of bead chain20is not properly secured. Thus, before installation no additional movement of bead chain20is required to disable bead chain20from being able to transmit force and/or energy to drive adapter728.

During vertical movement of first gear720relative to second gear726, the centers or axes of rotation of gears720,726and bead chain wheel718also move relative to each other. For example, when bead chain20is not tensioned as shown inFIG. 12, the centers of gears720,726are preferable co-extensive. When bead chain20is properly tensioned as shown inFIG. 13, the center of second gear726is vertically above the center of first gear720.

Preferably during installation, a lower end of bead chain20is coupled to window opening24with a bead tensioner22. During this movement, entire chain ring716moves down. Thus, both upper and lower halves of chain ring716move relative to housing712during the transition from preventing transmission of input to bead chain20to roller14to permitting transmission of input to bead chain20to roller14.

As discussed above, during proper initial installation which includes coupling of bead chain20to window opening24, first and second gears720,726engage by meshing as shown inFIGS. 13A and 13B. During rotation of chain ring716by bead chain20, teeth748of second gear726move into and out of engagement with teeth746of first gear726as gears720,726rotate. As shown inFIG. 13A, during normal operation, only a portion of teeth748of inner, second gear726mesh with teeth746of outer, first gear720. During rotation, the radial distance between adjacent teeth746,748changes. For example, when teeth746,748are positioned near the top of housing712during their rotation, these respective teeth746,748radially overlap so they mesh. When teeth746,748are positioned near the bottom of housing712during their rotation, these respective teeth are radially spaced apart so they do not mesh.

As shown inFIG. 13B, teeth748of second gear726are narrower than teeth746of first gear720. Similarly, the distance and angle between adjacent teeth748of second gear726is greater than the distance and angle between adjacent teeth746of first gear720. According to the preferred embodiment of the present disclosure, second gear726has fewer teeth748than first gear720has teeth746. According to the preferred embodiment, second gear726has ten teeth748and first gear720has eleven teeth746. As shown inFIG. 12, teeth748define an outer diameter that is less than an inner diameter defined by teeth746.

As also shown inFIG. 13B, teeth746,748of first and second gears720,726are dovetail shaped have undercuts. Teeth746have radially outer bases that are narrower than the radially inner ends of teeth746. Similarly, teeth748have radially inner bases that are narrower than the radially outer ends of teeth748. As a result, portions of teeth748are “tucked under” portions of teeth746when these respective teeth746,748mesh. Thus, portions of radially outer ends of teeth748of second gear726are radially positioned between portions of the radially inner ends of teeth746of first gear720and the remainder of first gear720.

As mentioned above, after initial installation, it is possible that bead chain20may lose its proper coupling if tensioner22is uncoupled from window opening24or otherwise. In response, gear separator730will disengage first gear720of chain ring716from second gear726by lifting chain ring716. According to the preferred embodiment, this disengagement does not require any rotation of chain ring716or any other component by bead chain20. Furthermore, this disengagement is independent of the relative rotational position of chain ring716relative to housing712, wrap springs714, clutch spring driver724, second gear726, drive adapter728, gear separator730, springs732, or roller14.

Although preferred embodiment clutch710uses meshing engagement between first gear720of chain ring716and second gear726to transmit movement of the bed chain20to roller14, other types of engagement may be provided. For example, internal gear teeth746of chain ring716may be replaced with frictional material, such as rubber or a gritty surface, and external gear teeth748of gear726may be replaced with a frictional material, such as rubber or a gritty surface. Movement of the frictional surfaces together under the downward force of properly coupled bead chain20causes enough frictional engagement between the frictional materials to transmit force and/or energy from bead chain20to roller14.

According to the preferred embodiment, the movement between chain ring716and second gear726that provides for engagement and disengagement is vertical. According to other embodiments, the movement may be horizontal, as shown inFIGS. 4A and 4B and 7A and 7B, or in any other direction.

A preferred embodiment tensioner822is shown inFIGS. 19-22C, tensioner822includes a base824, a shuttle assembly826, and a spring828that biases shuttle assembly826relative to base824. Base824includes a fastener-receiving aperture830for receiving a fastener (not shown) that couples tensioner822to a jamb, wall, or other surface of a window opening. Base824further includes a spring-receiving pocket832, a lug834, and a pair of aligned, pin-receiving apertures836. During assembly, spring828is positioned in spring-receiving pocket832of base824and a pin838is inserted through a lower loop840of spring828and pin-receiving apertures836to secure spring828in base824.

Shuttle assembly826includes a base842, a cover844, and pulley846. Base842includes a pulley shaft848, a base-receiving pocket850, and a pair of pin receiving apertures852. During assembly, pulley846is mounted on pulley shaft848; a pin838is inserted through an upper loop854of spring828and pin-receiving apertures852to secure spring828to base842; a portion of bead chain20is positioned under pulley846; and cover844is coupled to base842of shuttle assembly826over base824by snapping ramps856of cover844in snap-apertures858of base842. As a result of coupling cover844to base842of shuttle assembly826, bead chain20is trapped within tensioner822.

Shuttle assembly826telescopically receives base824and spring828biases the combination toward a retracted length. Base842of shuttle assembly includes a slot860that receives lug834of base824. During the telescopic movement, lug834rides in slot860to guide shuttle assembly826.

During installation, clutch710is mounted in a bracket, as discussed above, or otherwise supported in window opening24. Next, base824of tensioner822is pulled downward to create tension in bead chain20. During this tensioning, tensioner822telescopically extends and spring828stretches. Horizontal lines827on base824provide a tensioning range on for how much base824should be pulled down from shuttle assembly826to provide proper tension. Once tensioner822applies the appropriate amount of tension on bead chain20, on or more fasteners (not shown) are extended through fastener-receiving aperture830and into window opening24to couple bead chain20to window opening24.

During this tensioning, chain ring716is pulled down relative to housing712against the bias of gear separator730. This movement engages first gear720with second gear726to allow bead chain20to rotation roller14.