US20070040419A1 - Foldable pawl and ratchet assembly - Google Patents

Abstract

A ratchet device for a rocking furniture member has a plurality of structural elements. The ratchet device temporarily retains the furniture member in multiple engaged positions and includes: a pawl assembly having a pawl link rotatably connected to a first structural element; a plastic pawl lever rotatably connected to the pawl link; a first biasing element positioned between the pawl link and the pawl lever which biases the pawl lever toward a contact position with the pawl link; and a U-shaped bracket rotatably coupled to the pawl link and fixed to the first structural element. A ratchet having engagement teeth is fixed to a second structural element and located with the engagement teeth in a rotational path of the pawl lever. A second biasing element connected between the pawl link and the U-shaped bracket biases the pawl lever to engage the ratchet teeth.

Description

FIELD OF THE INVENTION
• The present invention relates in general to furniture member operating mechanisms and more specifically to a device and method for operating a furniture leg rest assembly.
BACKGROUND OF THE INVENTION
• Conventionally, reclining articles of furniture (i.e., chairs, sofas, loveseats, and the like) require a mechanism to bias a leg rest assembly in the extended and stowed positions. Known mechanisms commonly include a large number of moving parts that tends to increase the manufacturing time and costs associated with the furniture.
• Most rocking chairs typically include an upholstered chair frame supported from a stationary base assembly in a manner permitting the chair frame to “rock” freely with respect to the base assembly. In order to provide enhanced comfort and convenience, many rocking chairs also include a “reclinable” seat assembly and/or an “extensible” leg rest assembly. For example, combination platform rocking/reclining chairs, as disclosed in Applicant's U.S. Pat. Nos. 3,096,121 and 4,179,157, permit reclining movement of the seat assembly and actuation of the leg rest assembly independently of the conventional “rocking” action. The leg rest assembly is operably coupled to a drive mechanism to permit the seat occupant to selectively move the leg rest assembly between its normally retracted (i.e., “stowed”) and elevated (i.e., “extended”) positions. The drive mechanism is manually-operated and includes a handle which, when rotated by the seat occupant, causes concurrent rotation of a drive rod for extending or retracting the leg rest assembly.
• As an additional comfort feature, a latching mechanism may also be provided for releasably retaining the chair frame in one or more rearwardly rocked or “tilted” positions on the base assembly following extension of the leg rest assembly towards its extended position. In this manner, normal “rocking” action of the rocking chair is inhibited until the leg rest assembly is returned to its normally “stowed” position. Applicant's above-mentioned U.S. patents each disclose the use of a “one-way” pawl and ratchet type latching mechanism having a pawl member supported for pivotable movement from the base assembly and a toothed ratchet sector fixed to the chair frame. An elongated U-shaped spring link is used to couple the pawl member to a drive link fixed to the drive rod.
• Movement of the pawl member between positions of engagement and disengagement with the toothed ratchet sector is caused in response to movement of the leg rest assembly between its extended and retracted positions, respectively. More particularly, when the handle is slightly rotated for partially extending the leg rest assembly, concurrent rotation of the drive rod and the drive link causes the spring link to forcibly pivot the pawl member toward the toothed ratchet sector until the locking tip of the pawl member is positioned in locked engagement with the teeth of the ratchet sector. Thereafter, continued rotation of the drive rod and drive link for completely extending the leg rest assembly causes “elastic” flexure of the elongated spring link for applying a compressive force on the pawl member.
• However, the magnitude of the compressive force exerted by flexure of the spring link can vary since the displacement between the drive rod and sequential ratchet points on the ratchet sector vary in response to rearward tilting movement of the chair frame. Therefore, the flexure of the elongated spring link must be sufficient to ensure that the compressive force exerted on the pawl member is sufficient to maintain locked engagement between the pawl member and the teeth of the ratchet sector throughout the entire range of rearward “tilting” movement of the chair frame. The common one-piece construction of the pawl arm and locking tip may not provide the optimum angle for engagement with the teeth of the ratchet sector. An improved pawl/ratchet assembly is therefore desirable to improve engagement between the pawl and ratchet assembly.
• Known leg rest mechanisms also provide multiple functional positions, which can be reached using a detent mechanism, which temporarily holds the leg rest at each successive position. As the furniture member rocks backward when the leg rest is moved between the successive positions, a noticeable ratcheting or clicking noise occurs as the pawl engages successive teeth of the ratchet. This noise results at least in part because common pawl members and ratchet sectors are both created of metal material which transmit contact noise. An improved pawl/ratchet assembly is therefore desirable to reduce this operational noise.
SUMMARY OF THE INVENTION
• According to one preferred embodiment for a foldable pawl and ratchet assembly of the present invention, a ratchet device for a furniture member having a plurality of structural elements is operable to temporarily retain the furniture member in each of a plurality of rotated engaged positions. The ratchet device includes a pawl assembly having a pawl link rotatably connectable to a first one of the structural elements of the furniture member; a pawl lever rotatably connectable to the pawl link; and a biasing element operable to bias the pawl lever toward a contact position with the pawl link. A ratchet assembly includes a ratchet body having a plurality of engagement teeth. The ratchet assembly is fixed to a second one of the structural elements and located to position the engagement teeth in a rotational path of the pawl lever upon rotation of the pawl link.
• In another aspect of the invention, a ratchet device for a rocking furniture member has a plurality of structural elements. The ratchet device temporarily retains the furniture member in multiple engaged positions and includes: a pawl assembly having a pawl link rotatably connected to a first structural element; a plastic pawl lever rotatably connected to the pawl link; a first biasing element positioned between the pawl link and the pawl lever which biases the pawl lever toward a contact position with the pawl link; and a U-shaped bracket rotatably coupled to the pawl link and fixed to the first structural element. A ratchet having engagement teeth is fixed to a second structural element and located with the engagement teeth in a rotational path of the pawl lever. A second biasing element connected between the pawl link and the U-shaped bracket biases the pawl lever to engage the ratchet teeth.
• According to another aspect of the invention, a furniture member leg rest mechanism is connectable to both a furniture member structure and a seat frame. The leg rest mechanism includes a drive mechanism having a drive rod for rotational movement in a first and second direction, an actuator permits a seat occupant to selectively actuate the drive mechanism, a ratchet providing a plurality of ratchet teeth, and a pawl assembly having two independently rotatable members.
• According to still another aspect of the invention, a method for creating a pawl and ratchet assembly operable to position a furniture member in each of a plurality of engagement positions is provided.
• A foldable pawl and ratchet assembly of the present invention provides several advantages. By rotatably coupling a pawl lever to a pawl link, the pawl lever can more easily disengage from an engaged position between teeth of a ratchet, to allow continued backward rotation of a furniture member. The use of a polymeric material for the pawl lever provides a quieter operation as the pawl lever rotates past the teeth both between engaged positions and when pawl lever is released. The polymeric material also reduces the sliding contact friction between the pawl lever and teeth. A biasing element continuously biases pawl lever toward a contact position with pawl link which promotes engagement of a ratchet engaging end of pawl lever with teeth to prevent forward or return motion of the furniture member until the operator manually disengages the leg rest operating mechanism and pawl assembly together.
• Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating some aspects of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
• The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
• FIG. 1 is a front perspective view of a reclining chair having a foldable pawl and ratchet assembly of the present invention;
• FIG. 2 is an exploded perspective view of a chair with upholstery, biasing elements and other parts removed from the pre-assembled components for illustrating the adjustable spring toggle assembly for an actuation mechanism;
• FIG. 3 is a plan view of the leg rest mechanism in accordance with a preferred embodiment of the present invention;
• FIG. 4 is a cross sectional side elevational view taken at section4-4 ofFIG. 3;
• FIG. 5 is a front perspective exploded assembly view of the folding pawl assembly of one aspect of the present invention;
• FIG. 6 is a front elevational view of the pawl lever ofFIG. 5;
• FIG. 7 is a cross sectional view taken at section7-7 ofFIG. 6;
• FIG. 8 is a cross sectional view taken at section8-8 ofFIG. 6;
• FIG. 9 is a cross sectional plan view taken at section9-9 ofFIG. 6;
• FIG. 10 is a rear elevational view of the pawl link ofFIG. 5;
• FIG. 11 is a side elevational view of the pawl link ofFIG. 10;
• FIG. 12 is a top plan view of the pawl link ofFIG. 10;
• FIG. 13 is a cross sectional partial side elevational view similar toFIG. 4 showing the folding pawl assembly disengaged from teeth of the ratchet assembly;
• FIG. 14 is a cross sectional partial side elevational view similar toFIG. 13 showing the folding pawl assembly engaged with teeth of the ratchet assembly;
• FIG. 15 is an exploded elevational view of the ratchet engagement end of the pawl lever in contact with the ratchet teeth;
• FIG. 16 is a cross sectional partial side elevational view similar toFIG. 14 showing partial disengagement of the pawl lever from the ratchet teeth;
• FIG. 17 is a cross sectional side elevational view similar toFIG. 4, further showing the leg rest assembly in an extended position; and
• FIG. 18 is a rear perspective view of a linkage assembly of one aspect of the invention operable to engage the folding pawl assembly with the ratchet.
DETAILED DESCRIPTION
• The following description of some preferred aspects of the present invention is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
• With particular reference now to the drawings, in accordance with the teachings of the present invention and referring generally toFIG. 1, afurniture member10 such as a rocking, reclining chair includes anactuation mechanism12 for use in single ormulti-person furniture members10. In the aspect shown,furniture member10 is a chair, however, the invention is not limited to chairs.Furniture member10 can be any of a plurality of furniture members, including, but not limited to chairs, sofas and/or loveseats.Furniture member10 andactuation mechanism12 in the Figures herein are further shown representing a rocking configuration.Actuation mechanism12 controls the position of aleg rest14 between a stowed position (shown in phantom) and an extended position (partially shown) by operation of ahand lever16 in a rotation direction A. Rotation ofhand lever16 in direction A rotatesleg rest14 in a direction B. It will be apparent that rotation ofhand lever16 in an opposite direction from direction A will return theleg rest14 to the stowed position.Furniture member10 can further “rock” or rotate on arotational axis18 about arcs of rotation C and C′.
• Referring generally now toFIG. 2, the functional and structural aspects ofactuation mechanism12, shown operably suspended from the various pre-upholstered box-like frame components of furniture member10 (partially shown), will now be described.Actuation mechanism12 includes a springbiased toggle assembly20 to bias aleg rest assembly22 in either of the stowed (shown) or extended positions. Moreover, single biasingelement toggle assembly20 simplifies the assembly process and improves the reliability of theactuation mechanism12. In the disclosed embodiments,furniture member10 includespre-assembled actuation mechanism12 and various upholstered frame components (not shown). Moreover, since theactuation mechanism12 of the present invention is relatively compact in size, the use of loose upholstered cushions, which is an important feature in marketing various styles of chair, sofa or loveseat furniture, is also possible.
• For purposes of clarity,FIG. 2 shows the various pre-assembled frame components with their upholstery, padding, springs, etc. removed to better illustrate the interdependency of the frame components' construction which can be rapidly and rigidly assembled in a relative easy and efficient manner. Therefore, all of the frame components can be individually fabricated or sub-assembled to include the requisite brackets, springs, padding and upholstery on an “off-line” batch-type basis. Thereafter, the various pre-assembled and upholstered frame components are assembled for totally integratingactuation mechanism12 therein.
• As best seen in reference toFIGS. 2 through 4,actuation mechanism12 offurniture member10 is integrated into and operably suspended from left and right side (in reference to a seated user of furniture member10)frame assemblies24,25. In addition toside frame assemblies24,furniture member10 also includes front andrear rail assemblies26,28, respectively, which when interconnected define a rigid “box-like”chair frame29. Aseat assembly30 of a substantially rectangular shaped wooden frame is supported within theside frame assemblies24. As will be described in greater detail hereinafter,actuation mechanism12 includes adrive rod32 andfront support shaft34, both of which are spatially oriented to be “suspended” from left and rightside frame assemblies24,25.
• Actuation mechanism12 supportsleg rest assembly22 thereon. More specifically,leg rest assembly22 includes left andright pantograph linkages36,37 and toggleassembly20 which is operably associated withdrive rod32 andfront support shaft34 to selectively actuateleg rest assembly22. Arigid cross-brace38 is secured betweendrive rod32 andfront support shaft34 for providing structural rigidity withinactuation mechanism12. One end ofcross-brace38 is journally supported ondrive rod32 while the opposite end thereof is configured as abracket40 which is fixedly secured (such as by suitable threaded fasteners) to aninner surface42 offront rail assembly26. Furthermore,front support shaft34 is fixed to an intermediate portion ofcross-brace38 to inhibit rotation offront support shaft34 upon rotation ofdrive rod32. In one preferred construction,drive rod32 is an elongated rectangular shaped shaft having hand lever16 (shown inFIG. 1) provided adjacent an upholstered exterior portion of one of left or rightside frame assemblies24,25 that can be easily reached by a person seated infurniture member10 for convenient actuation thereof.
• As best seen inFIG. 2, most of the structural frame components such as left and rightside frame assemblies24,25,front rail assembly26,rear rail assembly28,seat assembly30, and a legrest frame board44 are each constructed in a manner which enables them to support connecting elements, padding, upholstery, etc. in order to complete a decorative andstylish furniture member10. Preferably, each of these frame components is fabricated from one or more wood panels and/or rails that are fixedly secured together by suitable fasteners, such as dowels, staples, nails and screws, and which may be reinforced at critical joints by metal reinforcement plates or brackets and/or wood corner blocks in a known manner. As previously noted, each frame component is individually pre-assembled for subsequent assembly into thefurniture member10. However, it is to be understood that the specific construction shown for each frame component is merely exemplary in nature.
• Frame board44 has anouter surface45 that is padded and upholstered.Frame board44 is supported and moved by identical left and righthand pantograph linkages36,37 throughapertures46 offront rail assembly26.Pantograph linkages36,37 may be similar in function and structure to that shown in FIG. 3 of U.S. Pat. No. 3,096,121, assigned to the common Assignee of the present invention, with the exception that pantographlinkages36,37 are operably suspended about the second set of “fixed” suspension points defined byfront support shaft34.
• Referring now more specifically toFIGS. 3 and 4, aratchet48 is fastenably mounted toinner surface42 offront rail assembly26. Afolding pawl assembly50 is moved from a non-engaged position shown to an engaged position with a plurality ofteeth52 ofratchet48 by adrive link54 of alinkage assembly56 which responds to rotation ofdrive rod32 usinghand lever16 to position arotatable pawl lever58 into operable contact withteeth52 ofratchet48.Pawl lever58 is pinned for rotation about an arc of rotation “D” to apawl link60 by afirst pin62. Pawl link60 is itself rotatably pinned to a substantiallyU-shaped bracket64 by asecond pin66 for rotation about an arc of rotation “E”. A biasingelement68 such as a torsion spring of spring metal normally biases pawllink60 towardratchet48.U-shaped bracket64 is mounted such as byfasteners70 to across frame member72 ofchair frame29.
• Referring now generally toFIGS. 5-12,pawl lever58 in one aspect is a polymeric material such as nylon, and is formed for example by injection molding and includes amain body portion74 with opposedintegral walls76,78 extending substantially perpendicular tomain body portion74. Each of a co-axially aligned pair ofclearance apertures80,82 are created through one ofopposed walls76,78. Aratchet engaging end84 substantially defining an apex is created at an opposite end ofmain body portion74 from the location ofclearance apertures80,82.Pawl lever58 can also be created from a composite material or a polymeric material other than nylon having hardness and wear resistance properties similar to nylon.
• Referring more specifically toFIGS. 5 and 10-12,pawl link60 is substantially U-shaped and includes integral opposed first andsecond link walls86,88 extending substantially perpendicular to amain wall90. Pawl link60 further includes at a link first end92 a co-axially aligned pair of first and second throughapertures94,96 which are both co-axially alignable withclearance apertures80,82 ofpawl lever58. First and second throughapertures94,96 are individually created through one of opposed first andsecond link walls86,88. Ahook98 is positioned proximate to linkfirst end92 and is created such as by a punching or stamping operation inmain wall90. At a linksecond end100 ofpawl link60, a co-axially aligned pair of third and fourth throughapertures102,104 are individually created through one of first andsecond link walls86,88. In one aspect of the invention,pawl link60 is a metal material such as steel or aluminum which is stamped or similarly formed to provideapertures94,96,102, and104, andhook98, and then bent to create the opposed first andsecond link walls86,88. In other aspects,pawl link60 can be of a formed polymeric material or a composite material.
• Referring specifically toFIG. 5,U-shaped bracket64 includes a bracketcommon wall106 and integral opposed first andsecond legs108,110 which extend substantially perpendicular tocommon wall106. Each of opposed first andsecond legs108,110 include a first andsecond aperture112,114 respectively, which are co-axially aligned with each other and are co-axially alignable with third and fourth throughapertures102,104 ofpawl link60. At least onefastener receiving aperture116 is provided incommon wall106 to receive one of fastener(s)70 used to mountU-shaped bracket64 to crossframe member72. A raisedelement118 can also be provided, for example by partially stamping a portion of bracketcommon wall106. Raisedelement118 provides a stop location to limit the rearward travel ofpawl link60 to prevent overstressing biasingelement68.
• Foldingpawl assembly50 is assembled as follows. To rotatablycouple pawl lever58 topawl link60,first pin62 is inserted throughclearance aperture82 ofpawl lever58, through second throughaperture96 ofpawl link60, and a first loopedportion120 of abiasing element122 such as a torsion spring.First pin62 is then further inserted through a second loopedportion124 of biasingelement122, through first throughaperture94 ofpawl link60 and out throughclearance aperture80 ofpawl lever58. A pindistal end126 offirst pin62 receives aretention fastener128 to rotatably retainfirst pin62. In other aspects,first pin62 is assembled in a reverse order to that described above.
• Pawl link60 is rotatably joined toU-shaped bracket64 as follows.Second pin66 is first inserted throughsecond aperture114 ofU-shaped bracket64, then inserted through a first loopedsection130 of biasingelement68, and into fourth throughaperture104 ofpawl link60.Second pin66 is then inserted in third throughaperture102 ofpawl link60, through a second loopedsection132 of biasingelement68, and out throughfirst aperture112 ofU-shaped bracket64. A pindistal end134 ofsecond pin66 receives aretention fastener136, similar toretention fastener128, to rotatably retainsecond pin66. In other aspects,second pin66 is assembled in a reverse order to that described above.
• As best seen inFIG. 5, when foldingpawl assembly50 is assembled, acontact end138 of biasingelement122 contactsmain body portion74 ofpawl lever58 and a pair of first and second free ends140,141 (only firstfree end140 is visible inFIG. 5) contactmain wall90 ofpawl link60. Also partially visible is a perimeter-shape-matchingend142 of biasingelement68 which is contoured to closely follow anouter perimeter144 ofpawl link60. First and secondfree portions146,148 of biasingelement68 engage bracketcommon wall106 ofU-shaped bracket64.
• Referring more specifically toFIGS. 6-9,pawl lever58 further includes: a total width “F”; a distance “G” between a centerline ofclearance apertures80,82 to ratchet engagingend84; a thickness “H” ofratchet engaging end84; and a distance “J” between inner facing surfaces ofwalls76,78. In one aspect, total width “F” is approximately 3.72 cm, distance “G” is approximately 5.08 cm, thickness “H” is approximately 0.46 cm, and distance “J” is approximately 2.96 cm. In one aspect, ratchet engagingend84 defines an angle α of approximately 70 degrees with aninner face85.
• Referring more specifically toFIGS. 10-12,pawl link60 further includes: a total length “K”; a total width “L”; a distance “M” from the co-axial aligned centerlines of third and fourth throughapertures102,104 to a centerline ofhook98; a first andsecond aperture152,154 inmain wall90 acting for example as pilot holes to help align a corresponding stamping die forpawl link60; a height “N” from the co-axial aligned centerlines of third and fourth throughapertures102,104 to the co-axial aligned centerlines of first and second throughapertures94,96; and a height “P” measured from an end ofpawl link60 proximate to third and fourth throughapertures102,104 to the co-axial aligned centerlines of third and fourth throughapertures102,104. In one aspect, total length “K” is approximately 11.43 cm, total width “L” is approximately 2.86 cm, distance “M” is approximately 8.25 cm, height “N” is approximately 10.16 cm, and height “P” is approximately 0.63 cm. Each of first andsecond link walls86,88 define an angle θ frommain wall90 of approximately 90 degrees.
• As best seen in reference toFIG. 13, a disengaged position of foldingpawl assembly50 is shown. In the disengaged position,pawl lever58 is biased into contact withpawl link60 by the biasing force provided by biasing member122 (shown inFIG. 5) wherein an inner surface150 (shown inFIG. 8) ofpawl lever58 contacts pawllink60. In the pawl lever/pawl link contact position, an “over-center” position ofpawl lever58 with respect topawl link60 is defined as a perpendicular measurement defining a distance U measurable from a centerline or axis of rotation T offirst pin62 to an axis V. Axis V is defined as an imaginary line drawn fromratchet engaging end84 through an axis of rotation W ofsecond pin66. In one preferred embodiment, distance U is approximately 0.15 cm.Inner surface150 therefore controls distance U. The over-center position ensures thatpawl lever58 remains in contact withpawl link60 whenratchet engaging end84 engagesteeth52. This contact allows the direct transfer of the weight of leg rest assembly22 (through teeth52) frompawl lever58 throughpawl link60, without relying on the biasing force of biasingelement122. Also in the “over-center” contact position, further rotation ofpawl lever58 in a direction opposite to arc of rotation D with respect topawl link60 is prevented.
• Referring toFIGS. 1, 5, and13, the disengaged position of foldingpawl assembly50 is maintained by the connection ofdrive link54 to driverod32. An apertured distal end ofdrive link54 releasably engageshook98 ofpawl link60. In the stowed position ofleg rest assembly22,linkage assembly56 is oriented as shown havingdrive link54 retainingpawl lever58 out of contact withteeth52 ofratchet48. Drivelink54 therefore provides sufficient force to overcome the normal biasing force of biasingelement68. In the disengaged position,furniture member10 is free to rotate or rock aboutrotational axis18. From the disengaged position,pawl link60 can be rotated about arc of rotation E untilratchet engaging end84contacts teeth52 ofratchet48.
• Referring generally toFIGS. 1, 14 and15, whenhand lever16 is rotated in arc of rotation A (counterclockwise as viewed inFIG. 1),drive rod32 rotateslinkage assembly56 which directsdrive link54 to rotatepawl link60 about arc of rotation E (clockwise as viewed inFIG. 15) in a first direction towardratchet48.Pawl lever58 is thereby rotated withpawl link60 aboutsecond pin66 untilratchet engaging end84 ofpawl lever58 engages between an adjacent pair ofteeth52 ofratchet48. If the occupant offurniture member10 thereafter rocks further “backward” in the direction of arc of rotation C′ (shown inFIG. 1), the apex shape ofratchet engaging end84 and the “over-center” design of foldingpawl assembly50 maintainratchet engaging end84 in contact with further adjacent pairs ofteeth52. This provides multiple releasable “locked” positions offurniture member10 whereinfurniture member10 is prevented from rocking forward in the direction of arc of rotation C.
• As best seen in reference toFIG. 15, ratchet engagingend84 includes a rounded surface leading to a point substantially defining an apex. The apex includes an angle λ which is less than an included angle μ defined byteeth52, allowing the point of the apex (ratchet engaging end84) to contact a bottom of any one ofteeth52. The difference between angle λ and angle μ therefore defines a clearance angle ω between an edge of the apex and a face of one ofteeth52. The clearance angle ω reduces the surface areas in contact betweenratchet engaging end84 andteeth52, which allows easier release ofratchet engaging end84.
• As best seen in reference toFIGS. 1 and 16, to disengageratchet engaging end84 ofpawl assembly50 fromteeth52 ofratchet48, the occupant offurniture member10 rotateshand lever16 clockwise (as viewed inFIG. 1) in the direction of arc of rotation A′. Ashand lever16 is rotated,drive rod32 is also rotated in arc of rotation A′, which directsdrive link54 to returnpawl link60 about arc of rotation E′ in a second direction away fromratchet48.Leg rest14 returns to the stowed position andfurniture member10 can then freely rotate or “rock” aboutrotational axis18. Aspawl link60 begins to rotate away fromratchet48, the downward force exerted by the weight ofextended leg rest14 andleg rest assembly22 causesfront rail assembly26 and attachedratchet48 to move downward (as viewed inFIG. 16). This downward travel offront rail assembly26 causes pawllever58 to rotate about arc of rotation D against the biasing force of biasingelement122.Pawl lever58 rotates through arc of rotation D about axis of rotation X offirst pin62 untilpawl lever58 releases from contact withteeth52.
• By allowing rotation ofpawl lever58 about arc of rotation D in a folding motion relative topawl link60, an engagement pressure betweenpawl lever58 andteeth52 is reduced for further backward or counterclockwise rotation ofpawl assembly50 in the direction of arc of rotation E′. Surface contact betweenratchet engaging end84 andteeth52 is reduced by the rounded surface ofratchet engaging end84 and clearance angle ω, which further reduces the ratchet release noise common to known operating mechanisms during drop of the leg rest assembly. By combining the features of a polymeric material forpawl lever58 and rotation ofpawl lever58 about arc of rotation D, the sound generated bypawl lever58 in contact withteeth52 is reduced. This reduces the overall operational sound level offurniture member10 during use ofleg rest14. The effort to releasepawl lever58 fromratchet48 is also substantially eliminated because of the present invention's use of a rotational connection betweenpawl lever58 andpawl link60. By allowingpawl lever58 to rotate or fold away from the engaged position withteeth52 ofratchet48, ratchet engagingend84 rotates away fromteeth52 which is advantageous over prior designs where disconnection fromteeth52 required a sliding motion with inherent friction over the length ofteeth52 until complete disengagement fromteeth52 was achieved.
• Referring now generally toFIG. 17,leg rest14 is shown in an extended position. Further rearward or counterclockwise rotation offurniture member10 about arc of rotation C′ andleg rest14 in an arc of rotation R causespawl lever58 to engagesubsequent teeth52 ofratchet48 in further engaged positions. In the engaged positions,furniture member10 is prevented from rocking forward or clockwise as viewed inFIG. 17. In some aspects of the invention, a ratchet-type detent mechanism150 similar todetent mechanism 40 disclosed in U.S. Pat. No. 6,655,732 to LaPointe, co-owned by the assignee of the present invention and incorporated herein by reference, engagesleg rest assembly22 in multiple functional stepped positions, each temporarily fixingleg rest assembly22 in one of the stepped positions and preventingleg rest assembly22 from dropping down due to the leg weight of an occupant.Ratchet48 andfolding pawl assembly50 therefore prevent rocking motion offurniture member10 whiledetent mechanism150 retainsleg rest assembly22 at a desired position. Multiple forces unique to each different furniture member are balanced to prevent leg rest downward drop or backward drift, such as a frame and a leg rest assembly weight, tension provided by the material covering ofseat assembly30, tension from straps used to mount pads or material toseat assembly30, and the tension provided by a biasingelement153 provided withtoggle assembly20.
• Referring now toFIG. 18,linkage assembly56 is shown in greater detail. Anadapter154 is slidably received alongdrive rod32. Aswivel link156 is coupled toadapter154.Adapter154 is fastenably connected to driverod32 using one ormore fasteners158. Apin160 is received in anaperture162 ofswivel link156 and an aperture (not shown) ofdrive link54. Afastener164 retainspin160. A distal end ofdrive link54 includes anaperture166 which receiveshook98 ofpawl link60. In addition, ratchet48 includes raisedembossments168,170 which receive fasteners used to mountratchet48 tofront rail assembly26.
• A functional correlation exists between the width F ofpawl lever58 and a width Y ofteeth52 ofratchet48 and the load characteristics ofactuation mechanism12. By increasing a bearing surface or contact area betweenpawl lever58 andteeth52, for example by increasing both width F and width Y, a load capacity ofactuation mechanism12 can be increased. This is beneficial to accommodate heavier occupants offurniture member10. A functional correlation also exists between width F ofpawl lever58 and width Y ofteeth52 and the acoustic characteristics ofactuation mechanism12. For example, by increasing both width F and width Y noise generated during use offurniture member10 decreases for heavier occupants.
• A foldable pawl and ratchet assembly of the present invention provides several advantages. By rotatably coupling apawl lever58 to apawl link60, thepawl lever58 can more easily disengage fromteeth52 of aratchet48, which reduces a ratcheting sound. The use of a polymeric material forpawl lever58 provides a quieter operation aspawl lever58 ratchets overteeth52 between different engaged positions. The polymeric material also reduces the sliding contact friction between thepawl lever58 andteeth52. A biasingelement122 continuously biases pawllever58 toward an over-center contact position withpawl link60 which allowspawl link60 andpawl lever58 to transfer the weight load of the leg rest assembly. A biasingelement68 promotes engagement of aratchet engaging end84 ofpawl lever58 withteeth52 to prevent forward or return motion of the furniture member until the operator manually disengages the leg rest operating mechanism and pawl assembly together. A clearance angle of theratchet engaging end84 ofpawl lever58 reduces contact withteeth52 which further assists in releasingpawl lever58.
• The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims (38)

1. A ratchet device for a furniture member having a plurality of structural elements, the ratchet device operable to temporarily retain the furniture member in each of a plurality of rotated engaged positions, the ratchet device comprising:

a pawl assembly including:

a pawl link rotatably connectable to a first one of the structural elements of the furniture member;

a pawl lever rotatably connectable to the pawl link and biased toward an over-center contact position with the pawl link; and

a ratchet assembly including a ratchet body having a plurality of engagement teeth, the ratchet assembly fixedly connectable to a second one of the structural elements and located to position the engagement teeth in a rotational path of the pawl lever upon rotation of the pawl link.

2. The ratchet device ofclaim 1, further comprising a plurality of engaged positions each having the pawl lever engaged between proximate ones of the plurality of teeth, the pawl lever and the pawl link being positioned in the contact position in each of the engaged positions.

3. The ratchet device ofclaim 2, further comprising:

a stowed position of the pawl assembly having the pawl lever disengaged from any of the teeth;

wherein the pawl link is rotatable about an arc of rotation defining a first direction toward the ratchet assembly from the stowed position to any of the plurality of engaged positions, and a second direction away from the ratchet assembly.

4. The ratchet device ofclaim 3,

wherein the pawl lever is rotatable in the second direction to operably return the pawl lever and the pawl link from any of the plurality of engaged positions to the stowed position; and

wherein the pawl lever is rotatable about a second arc of rotation substantially toward the second direction with respect to the pawl link during disengagement of the pawl lever from the ratchet assembly.

5. The ratchet device ofclaim 1, further comprising:

a bracket fastenably connectable to the first one of the structural elements of the furniture member and adapted to rotatably receive the pawl link; and

a pin operable to rotatably connect the pawl link to the bracket.

6. The ratchet device ofclaim 5, further comprising a biasing element positioned in contact with both the pawl link and the bracket, the second biasing element operable to bias the pawl link toward the ratchet assembly.

7. The ratchet device ofclaim 1, wherein the pawl lever further comprises:

a main body portion;

first and second walls positioned in opposition to each other about the main body portion, the walls each integrally connected to the main body portion and extending substantially perpendicular to the main body portion; and

a biasing element having a first portion positioned between the first and second walls and in contact with the main body portion.

8. The ratchet device ofclaim 7, wherein the pawl link further comprises:

a main wall; and

first and second link walls positioned in opposition to each other about the main wall, the link walls each integrally connected to the main wall and extending substantially perpendicular to the main wall;

wherein a second portion of the biasing element is positioned between the first and second link walls and in contact with the main wall.

9. The ratchet device ofclaim 1, wherein the pawl lever comprises a polymeric material.

10. The ratchet device ofclaim 9, wherein the polymeric material further comprises a nylon material.

11. The ratchet device ofclaim 9, wherein the pawl link comprises one of a metal and a polymeric material.

12. The ratchet device ofclaim 9, wherein the ratchet comprises one of a metal and a polymeric material.

13. The ratchet device ofclaim 1, further comprising a pin operable to rotatably connect the pawl lever to the pawl link.

14. The ratchet device ofclaim 1, wherein the pawl lever further comprises a ratchet engaging end defining an apex, the apex further defining a clearance angle with a face of any of the engagement teeth, the clearance angle operable to limit contact between the ratchet engaging end and any of the engagement teeth.

15. The ratchet device ofclaim 1, further comprising a biasing element in contact with both the pawl lever and the pawl link operable to bias the pawl lever toward the over-center contact position.

16. The ratchet device ofclaim 1, wherein the over-center contact position defines a distance between:

a line extending from a center of rotation of the pawl link to a distal engagement end of the pawl lever; and

a center of rotation of the pawl link about the pawl lever.

17. A ratchet device for a rocking furniture member having a plurality of structural elements, the ratchet device operable to temporarily retain the furniture member in each of a plurality of engaged positions, the ratchet device comprising:

a pawl assembly including:

a pawl link rotatably connectable to a first one of the structural elements of the furniture member;

a polymeric pawl lever rotatably connectable to the pawl link;

a first biasing element disposed between the pawl link and the pawl lever operable to bias the pawl lever toward a contact position with the pawl link; and

a substantially U-shaped bracket rotatably coupled to the pawl link and fixedly connected to one of the structural elements;

a ratchet assembly having a plurality of engagement teeth, the ratchet assembly fixedly connectable to a second one of the structural elements and located to position the engagement teeth in a rotational path of the pawl lever upon rotation of the pawl link; and

a second biasing element connected between the pawl link and the U-shaped bracket operable to bias the pawl lever toward the ratchet assembly.

18. The ratchet device ofclaim 17, further comprising a first pin rotatably coupling the pawl lever to the pawl link.

19. The ratchet device ofclaim 18, wherein the pawl lever further comprises a main body portion having integral opposing walls extending substantially perpendicular to the main body portion, each of the opposing walls having an aperture adapted to receive the first pin.

20. The ratchet device ofclaim 19, further comprising a second pin rotatably coupling the pawl link to the bracket.

21. The ratchet device ofclaim 17, wherein the pawl link further comprises a main wall having integral opposing link walls extending substantially perpendicular to the main wall, each of the opposing link walls having a through aperture adapted to receive the second pin.

22. The ratchet device ofclaim 21, wherein the pawl link further comprises a hook positioned in the main wall, the hook adapted to receive a drive link operable to rotate the pawl link about the second pin both toward and away from the ratchet assembly.

23. The ratchet device ofclaim 17, wherein the polymeric pawl lever further comprises a nylon material.

24. The ratchet device ofclaim 17, wherein the U-shaped bracket further comprises a raised element operable as a rotational stop for the pawl link.

25. A furniture member leg rest mechanism connectable to both a furniture member structure and a seat frame, the leg rest mechanism comprising:

a drive mechanism including a drive rod for rotational movement in a first and second direction;

an actuator for permitting a seat occupant to selectively actuate the drive mechanism;

a ratchet having a plurality of ratchet teeth formed thereon;

a pawl assembly, including:

a pawl link having a first end pivotally connectable to the frame for rotational movement of the pawl link between a first position and a second position, and a second end;

a pawl lever pivotally coupled to the second end of the pawl link, the pawl lever lockingly engaging the ratchet teeth in the first position wherein the frame is releasably locked in a rearwardly tilted position, and a second position released from the ratchet teeth for permitting unrestricted rocking movement of the seat frame.

26. The leg rest mechanism ofclaim 25, further comprising:

a release assembly including a swivel link supported on the drive rod for free rotation thereabout; and

a rigid drive link having a first end coupled to the pawl link and a second end pivotally connected to the swivel link;

wherein the pawl link further comprises a hook formed thereon for engaging the release link to couple said release assembly to said pawl link.

27. The leg rest mechanism ofclaim 26, wherein the pawl lever is substantially U-shaped in cross section having a main body portion and a pair of laterally extending walls, the main body portion having a ratchet engaging end defining an axis for engaging the ratchet, and each of the walls having an aperture therethrough for pivotally coupling the pawl lever to the pawl link.

28. The leg rest mechanism ofclaim 25, further comprising a substantially U-shaped bracket having a first portion secured to the structure and a pair of laterally spaced legs for receiving the pawl link therebetween, each of the legs having an aperture therethrough for receiving a pin to pivotally couple the pawl link to the bracket.

29. The leg rest mechanism ofclaim 25, further comprising a biasing element for normally biasing the pawl link toward the first position, the biasing element adapted to exert an engagement force on the pawl link for maintaining locked engagement of the pawl lever with the ratchet teeth when the pawl link is in the first position.

30. A ratchet device for a furniture member, the furniture member including a plurality of structural elements, the ratchet device comprising:

a pawl assembly including:

a pawl link rotatably connectable to a first one of the structural elements of the furniture member;

a pawl lever rotatably connectable to the pawl link, the pawl lever including an engagement end having a substantially rounded surface; and

a biasing element operable to bias the pawl lever toward an over-center contact position with the pawl link; and

a ratchet assembly including a ratchet body having a plurality of engagement teeth, the ratchet assembly fixedly connectable to a second one of the structural elements and located to position the engagement teeth in a rotational path of the pawl lever upon rotation of the pawl link;

a plurality of engaged positions between the engagement end of the pawl lever and adjacent pairs of the engagement teeth, the ratchet device operable to temporarily retain the furniture member in each of a plurality of rotated engaged positions having the pawl lever in the over-center contact position; and

a release path defined when the pawl link is rotated about the rotational path away from ratchet assembly, the pawl lever being rotatably released from the over-center contact position and the substantially rounded surface operable to release the pawl lever in a folding motion from the engagement teeth.

31. The ratchet device ofclaim 30, wherein the pawl lever comprises a polymeric material.

32. The ratchet device ofclaim 30, further comprising a pin operable to rotatably connect the pawl lever to the pawl link.

33. The ratchet device ofclaim 30, further comprising a second biasing element operable to bias the pawl link toward the ratchet assembly.

34. The ratchet device ofclaim 30, further comprising a drive link connectable to the pawl link and operable to translate the pawl link about the release path.

35. A method for creating a pawl and ratchet assembly operable to position a furniture member in each of a plurality of engagement positions, the pawl and ratchet assembly having a pawl lever, a pawl link, and a ratchet having a plurality of engagement teeth, the furniture member having a plurality of structural elements, the method comprising:

rotatably connecting the pawl link to one of the structural elements of the furniture member;

rotatably coupling the pawl lever to the pawl link;

engaging a biasing element with both the pawl lever and the pawl link operable to bias the pawl lever toward a contact position with the pawl link; and

fixedly connecting the ratchet assembly to a second one of the structural elements having the engagement teeth in alignment with in a rotational path of the pawl lever to operably permit the pawl lever to engage the engagement teeth.

36. The method ofclaim 35, further comprising creating the pawl lever from a polymeric material.

37. The method ofclaim 35, further comprising increasing a width of both the pawl lever and the engagement teeth to accommodate an occupant weight.

38. The method ofclaim 35, further comprising increasing a width of both the pawl lever and the engagement teeth to decrease a ratcheting sound level of the pawl and ratchet assembly.

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