U.S. patent application number 11/205127 was filed with the patent office on 2007-02-22 for foldable pawl and ratchet assembly.
Invention is credited to Larry P. LaPointe, Richard E. Marshall.
Application Number | 20070040419 11/205127 |
Document ID | / |
Family ID | 37758309 |
Filed Date | 2007-02-22 |
United States Patent
Application |
20070040419 |
Kind Code |
A1 |
LaPointe; Larry P. ; et
al. |
February 22, 2007 |
Foldable pawl and ratchet assembly
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.
Inventors: |
LaPointe; Larry P.;
(Temperance, MI) ; Marshall; Richard E.; (Monroe,
MI) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
37758309 |
Appl. No.: |
11/205127 |
Filed: |
August 16, 2005 |
Current U.S.
Class: |
297/69 |
Current CPC
Class: |
A47C 1/0345
20130101 |
Class at
Publication: |
297/069 |
International
Class: |
A47C 1/02 20060101
A47C001/02 |
Claims
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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 1, wherein the pawl lever comprises
a polymeric material.
10. The ratchet device of claim 9, wherein the polymeric material
further comprises a nylon material.
11. The ratchet device of claim 9, wherein the pawl link comprises
one of a metal and a polymeric material.
12. The ratchet device of claim 9, wherein the ratchet comprises
one of a metal and a polymeric material.
13. The ratchet device of claim 1, further comprising a pin
operable to rotatably connect the pawl lever to the pawl link.
14. The ratchet device of claim 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 of claim 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 of claim 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 of claim 17, further comprising a first pin
rotatably coupling the pawl lever to the pawl link.
19. The ratchet device of claim 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 of claim 19, further comprising a second pin
rotatably coupling the pawl link to the bracket.
21. The ratchet device of claim 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 of claim 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 of claim 17, wherein the polymeric pawl
lever further comprises a nylon material.
24. The ratchet device of claim 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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 30, wherein the pawl lever
comprises a polymeric material.
32. The ratchet device of claim 30, further comprising a pin
operable to rotatably connect the pawl lever to the pawl link.
33. The ratchet device of claim 30, further comprising a second
biasing element operable to bias the pawl link toward the ratchet
assembly.
34. The ratchet device of claim 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 of claim 35, further comprising creating the pawl
lever from a polymeric material.
37. The method of claim 35, further comprising increasing a width
of both the pawl lever and the engagement teeth to accommodate an
occupant weight.
38. The method of claim 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.
Description
FIELD OF THE INVENTION
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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
[0014] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0015] FIG. 1 is a front perspective view of a reclining chair
having a foldable pawl and ratchet assembly of the present
invention;
[0016] 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;
[0017] FIG. 3 is a plan view of the leg rest mechanism in
accordance with a preferred embodiment of the present
invention;
[0018] FIG. 4 is a cross sectional side elevational view taken at
section 4-4 of FIG. 3;
[0019] FIG. 5 is a front perspective exploded assembly view of the
folding pawl assembly of one aspect of the present invention;
[0020] FIG. 6 is a front elevational view of the pawl lever of FIG.
5;
[0021] FIG. 7 is a cross sectional view taken at section 7-7 of
FIG. 6;
[0022] FIG. 8 is a cross sectional view taken at section 8-8 of
FIG. 6;
[0023] FIG. 9 is a cross sectional plan view taken at section 9-9
of FIG. 6;
[0024] FIG. 10 is a rear elevational view of the pawl link of FIG.
5;
[0025] FIG. 11 is a side elevational view of the pawl link of FIG.
10;
[0026] FIG. 12 is a top plan view of the pawl link of FIG. 10;
[0027] FIG. 13 is a cross sectional partial side elevational view
similar to FIG. 4 showing the folding pawl assembly disengaged from
teeth of the ratchet assembly;
[0028] FIG. 14 is a cross sectional partial side elevational view
similar to FIG. 13 showing the folding pawl assembly engaged with
teeth of the ratchet assembly;
[0029] FIG. 15 is an exploded elevational view of the ratchet
engagement end of the pawl lever in contact with the ratchet
teeth;
[0030] FIG. 16 is a cross sectional partial side elevational view
similar to FIG. 14 showing partial disengagement of the pawl lever
from the ratchet teeth;
[0031] FIG. 17 is a cross sectional side elevational view similar
to FIG. 4, further showing the leg rest assembly in an extended
position; and
[0032] 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
[0033] 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.
[0034] With particular reference now to the drawings, in accordance
with the teachings of the present invention and referring generally
to FIG. 1, a furniture member 10 such as a rocking, reclining chair
includes an actuation mechanism 12 for use in single or
multi-person furniture members 10. In the aspect shown, furniture
member 10 is a chair, however, the invention is not limited to
chairs. Furniture member 10 can be any of a plurality of furniture
members, including, but not limited to chairs, sofas and/or
loveseats. Furniture member 10 and actuation mechanism 12 in the
Figures herein are further shown representing a rocking
configuration. Actuation mechanism 12 controls the position of a
leg rest 14 between a stowed position (shown in phantom) and an
extended position (partially shown) by operation of a hand lever 16
in a rotation direction A. Rotation of hand lever 16 in direction A
rotates leg rest 14 in a direction B. It will be apparent that
rotation of hand lever 16 in an opposite direction from direction A
will return the leg rest 14 to the stowed position. Furniture
member 10 can further "rock" or rotate on a rotational axis 18
about arcs of rotation C and C'.
[0035] Referring generally now to FIG. 2, the functional and
structural aspects of actuation mechanism 12, shown operably
suspended from the various pre-upholstered box-like frame
components of furniture member 10 (partially shown), will now be
described. Actuation mechanism 12 includes a spring biased toggle
assembly 20 to bias a leg rest assembly 22 in either of the stowed
(shown) or extended positions. Moreover, single biasing element
toggle assembly 20 simplifies the assembly process and improves the
reliability of the actuation mechanism 12. In the disclosed
embodiments, furniture member 10 includes pre-assembled actuation
mechanism 12 and various upholstered frame components (not shown).
Moreover, since the actuation mechanism 12 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.
[0036] 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 integrating actuation mechanism 12
therein.
[0037] As best seen in reference to FIGS. 2 through 4, actuation
mechanism 12 of furniture member 10 is integrated into and operably
suspended from left and right side (in reference to a seated user
of furniture member 10) frame assemblies 24, 25. In addition to
side frame assemblies 24, furniture member 10 also includes front
and rear rail assemblies 26, 28, respectively, which when
interconnected define a rigid "box-like" chair frame 29. A seat
assembly 30 of a substantially rectangular shaped wooden frame is
supported within the side frame assemblies 24. As will be described
in greater detail hereinafter, actuation mechanism 12 includes a
drive rod 32 and front support shaft 34, both of which are
spatially oriented to be "suspended" from left and right side frame
assemblies 24, 25.
[0038] Actuation mechanism 12 supports leg rest assembly 22
thereon. More specifically, leg rest assembly 22 includes left and
right pantograph linkages 36, 37 and toggle assembly 20 which is
operably associated with drive rod 32 and front support shaft 34 to
selectively actuate leg rest assembly 22. A rigid cross-brace 38 is
secured between drive rod 32 and front support shaft 34 for
providing structural rigidity within actuation mechanism 12. One
end of cross-brace 38 is journally supported on drive rod 32 while
the opposite end thereof is configured as a bracket 40 which is
fixedly secured (such as by suitable threaded fasteners) to an
inner surface 42 of front rail assembly 26. Furthermore, front
support shaft 34 is fixed to an intermediate portion of cross-brace
38 to inhibit rotation of front support shaft 34 upon rotation of
drive rod 32. In one preferred construction, drive rod 32 is an
elongated rectangular shaped shaft having hand lever 16 (shown in
FIG. 1) provided adjacent an upholstered exterior portion of one of
left or right side frame assemblies 24, 25 that can be easily
reached by a person seated in furniture member 10 for convenient
actuation thereof.
[0039] As best seen in FIG. 2, most of the structural frame
components such as left and right side frame assemblies 24, 25,
front rail assembly 26, rear rail assembly 28, seat assembly 30,
and a leg rest frame board 44 are each constructed in a manner
which enables them to support connecting elements, padding,
upholstery, etc. in order to complete a decorative and stylish
furniture member 10. 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 the
furniture member 10. However, it is to be understood that the
specific construction shown for each frame component is merely
exemplary in nature.
[0040] Frame board 44 has an outer surface 45 that is padded and
upholstered. Frame board 44 is supported and moved by identical
left and right hand pantograph linkages 36, 37 through apertures 46
of front rail assembly 26. Pantograph linkages 36, 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 pantograph linkages 36, 37 are
operably suspended about the second set of "fixed" suspension
points defined by front support shaft 34.
[0041] Referring now more specifically to FIGS. 3 and 4, a ratchet
48 is fastenably mounted to inner surface 42 of front rail assembly
26. A folding pawl assembly 50 is moved from a non-engaged position
shown to an engaged position with a plurality of teeth 52 of
ratchet 48 by a drive link 54 of a linkage assembly 56 which
responds to rotation of drive rod 32 using hand lever 16 to
position a rotatable pawl lever 58 into operable contact with teeth
52 of ratchet 48. Pawl lever 58 is pinned for rotation about an arc
of rotation "D" to a pawl link 60 by a first pin 62. Pawl link 60
is itself rotatably pinned to a substantially U-shaped bracket 64
by a second pin 66 for rotation about an arc of rotation "E". A
biasing element 68 such as a torsion spring of spring metal
normally biases pawl link 60 toward ratchet 48. U-shaped bracket 64
is mounted such as by fasteners 70 to a cross frame member 72 of
chair frame 29.
[0042] Referring now generally to FIGS. 5-12, pawl lever 58 in one
aspect is a polymeric material such as nylon, and is formed for
example by injection molding and includes a main body portion 74
with opposed integral walls 76, 78 extending substantially
perpendicular to main body portion 74. Each of a co-axially aligned
pair of clearance apertures 80, 82 are created through one of
opposed walls 76, 78. A ratchet engaging end 84 substantially
defining an apex is created at an opposite end of main body portion
74 from the location of clearance apertures 80, 82. Pawl lever 58
can also be created from a composite material or a polymeric
material other than nylon having hardness and wear resistance
properties similar to nylon.
[0043] Referring more specifically to FIGS. 5 and 10-12, pawl link
60 is substantially U-shaped and includes integral opposed first
and second link walls 86, 88 extending substantially perpendicular
to a main wall 90. Pawl link 60 further includes at a link first
end 92 a co-axially aligned pair of first and second through
apertures 94, 96 which are both co-axially alignable with clearance
apertures 80, 82 of pawl lever 58. First and second through
apertures 94, 96 are individually created through one of opposed
first and second link walls 86, 88. A hook 98 is positioned
proximate to link first end 92 and is created such as by a punching
or stamping operation in main wall 90. At a link second end 100 of
pawl link 60, a co-axially aligned pair of third and fourth through
apertures 102, 104 are individually created through one of first
and second link walls 86, 88. In one aspect of the invention, pawl
link 60 is a metal material such as steel or aluminum which is
stamped or similarly formed to provide apertures 94, 96, 102, and
104, and hook 98, and then bent to create the opposed first and
second link walls 86, 88. In other aspects, pawl link 60 can be of
a formed polymeric material or a composite material.
[0044] Referring specifically to FIG. 5, U-shaped bracket 64
includes a bracket common wall 106 and integral opposed first and
second legs 108, 110 which extend substantially perpendicular to
common wall 106. Each of opposed first and second legs 108, 110
include a first and second aperture 112, 114 respectively, which
are co-axially aligned with each other and are co-axially alignable
with third and fourth through apertures 102, 104 of pawl link 60.
At least one fastener receiving aperture 116 is provided in common
wall 106 to receive one of fastener(s) 70 used to mount U-shaped
bracket 64 to cross frame member 72. A raised element 118 can also
be provided, for example by partially stamping a portion of bracket
common wall 106. Raised element 118 provides a stop location to
limit the rearward travel of pawl link 60 to prevent overstressing
biasing element 68.
[0045] Folding pawl assembly 50 is assembled as follows. To
rotatably couple pawl lever 58 to pawl link 60, first pin 62 is
inserted through clearance aperture 82 of pawl lever 58, through
second through aperture 96 of pawl link 60, and a first looped
portion 120 of a biasing element 122 such as a torsion spring.
First pin 62 is then further inserted through a second looped
portion 124 of biasing element 122, through first through aperture
94 of pawl link 60 and out through clearance aperture 80 of pawl
lever 58. A pin distal end 126 of first pin 62 receives a retention
fastener 128 to rotatably retain first pin 62. In other aspects,
first pin 62 is assembled in a reverse order to that described
above.
[0046] Pawl link 60 is rotatably joined to U-shaped bracket 64 as
follows. Second pin 66 is first inserted through second aperture
114 of U-shaped bracket 64, then inserted through a first looped
section 130 of biasing element 68, and into fourth through aperture
104 of pawl link 60. Second pin 66 is then inserted in third
through aperture 102 of pawl link 60, through a second looped
section 132 of biasing element 68, and out through first aperture
112 of U-shaped bracket 64. A pin distal end 134 of second pin 66
receives a retention fastener 136, similar to retention fastener
128, to rotatably retain second pin 66. In other aspects, second
pin 66 is assembled in a reverse order to that described above.
[0047] As best seen in FIG. 5, when folding pawl assembly 50 is
assembled, a contact end 138 of biasing element 122 contacts main
body portion 74 of pawl lever 58 and a pair of first and second
free ends 140, 141 (only first free end 140 is visible in FIG. 5)
contact main wall 90 of pawl link 60. Also partially visible is a
perimeter-shape-matching end 142 of biasing element 68 which is
contoured to closely follow an outer perimeter 144 of pawl link 60.
First and second free portions 146, 148 of biasing element 68
engage bracket common wall 106 of U-shaped bracket 64.
[0048] Referring more specifically to FIGS. 6-9, pawl lever 58
further includes: a total width "F"; a distance "G" between a
centerline of clearance apertures 80, 82 to ratchet engaging end
84; a thickness "H" of ratchet engaging end 84; and a distance "J"
between inner facing surfaces of walls 76, 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 engaging end 84
defines an angle .alpha. of approximately 70 degrees with an inner
face 85.
[0049] Referring more specifically to FIGS. 10-12, pawl link 60
further includes: a total length "K"; a total width "L"; a distance
"M" from the co-axial aligned centerlines of third and fourth
through apertures 102, 104 to a centerline of hook 98; a first and
second aperture 152, 154 in main wall 90 acting for example as
pilot holes to help align a corresponding stamping die for pawl
link 60; a height "N" from the co-axial aligned centerlines of
third and fourth through apertures 102, 104 to the co-axial aligned
centerlines of first and second through apertures 94, 96; and a
height "P" measured from an end of pawl link 60 proximate to third
and fourth through apertures 102, 104 to the co-axial aligned
centerlines of third and fourth through apertures 102, 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 and second link walls 86, 88
define an angle .theta. from main wall 90 of approximately 90
degrees.
[0050] As best seen in reference to FIG. 13, a disengaged position
of folding pawl assembly 50 is shown. In the disengaged position,
pawl lever 58 is biased into contact with pawl link 60 by the
biasing force provided by biasing member 122 (shown in FIG. 5)
wherein an inner surface 150 (shown in FIG. 8) of pawl lever 58
contacts pawl link 60. In the pawl lever/pawl link contact
position, an "over-center" position of pawl lever 58 with respect
to pawl link 60 is defined as a perpendicular measurement defining
a distance U measurable from a centerline or axis of rotation T of
first pin 62 to an axis V. Axis V is defined as an imaginary line
drawn from ratchet engaging end 84 through an axis of rotation W of
second pin 66. In one preferred embodiment, distance U is
approximately 0.15 cm. Inner surface 150 therefore controls
distance U. The over-center position ensures that pawl lever 58
remains in contact with pawl link 60 when ratchet engaging end 84
engages teeth 52. This contact allows the direct transfer of the
weight of leg rest assembly 22 (through teeth 52) from pawl lever
58 through pawl link 60, without relying on the biasing force of
biasing element 122. Also in the "over-center" contact position,
further rotation of pawl lever 58 in a direction opposite to arc of
rotation D with respect to pawl link 60 is prevented.
[0051] Referring to FIGS. 1, 5, and 13, the disengaged position of
folding pawl assembly 50 is maintained by the connection of drive
link 54 to drive rod 32. An apertured distal end of drive link 54
releasably engages hook 98 of pawl link 60. In the stowed position
of leg rest assembly 22, linkage assembly 56 is oriented as shown
having drive link 54 retaining pawl lever 58 out of contact with
teeth 52 of ratchet 48. Drive link 54 therefore provides sufficient
force to overcome the normal biasing force of biasing element 68.
In the disengaged position, furniture member 10 is free to rotate
or rock about rotational axis 18. From the disengaged position,
pawl link 60 can be rotated about arc of rotation E until ratchet
engaging end 84 contacts teeth 52 of ratchet 48.
[0052] Referring generally to FIGS. 1, 14 and 15, when hand lever
16 is rotated in arc of rotation A (counterclockwise as viewed in
FIG. 1), drive rod 32 rotates linkage assembly 56 which directs
drive link 54 to rotate pawl link 60 about arc of rotation E
(clockwise as viewed in FIG. 15) in a first direction toward
ratchet 48. Pawl lever 58 is thereby rotated with pawl link 60
about second pin 66 until ratchet engaging end 84 of pawl lever 58
engages between an adjacent pair of teeth 52 of ratchet 48. If the
occupant of furniture member 10 thereafter rocks further "backward"
in the direction of arc of rotation C' (shown in FIG. 1), the apex
shape of ratchet engaging end 84 and the "over-center" design of
folding pawl assembly 50 maintain ratchet engaging end 84 in
contact with further adjacent pairs of teeth 52. This provides
multiple releasable "locked" positions of furniture member 10
wherein furniture member 10 is prevented from rocking forward in
the direction of arc of rotation C.
[0053] As best seen in reference to FIG. 15, ratchet engaging end
84 includes a rounded surface leading to a point substantially
defining an apex. The apex includes an angle .lamda. which is less
than an included angle .mu. defined by teeth 52, allowing the point
of the apex (ratchet engaging end 84) to contact a bottom of any
one of teeth 52. The difference between angle .lamda. and angle
.mu. therefore defines a clearance angle .omega. between an edge of
the apex and a face of one of teeth 52. The clearance angle .omega.
reduces the surface areas in contact between ratchet engaging end
84 and teeth 52, which allows easier release of ratchet engaging
end 84.
[0054] As best seen in reference to FIGS. 1 and 16, to disengage
ratchet engaging end 84 of pawl assembly 50 from teeth 52 of
ratchet 48, the occupant of furniture member 10 rotates hand lever
16 clockwise (as viewed in FIG. 1) in the direction of arc of
rotation A'. As hand lever 16 is rotated, drive rod 32 is also
rotated in arc of rotation A', which directs drive link 54 to
return pawl link 60 about arc of rotation E' in a second direction
away from ratchet 48. Leg rest 14 returns to the stowed position
and furniture member 10 can then freely rotate or "rock" about
rotational axis 18. As pawl link 60 begins to rotate away from
ratchet 48, the downward force exerted by the weight of extended
leg rest 14 and leg rest assembly 22 causes front rail assembly 26
and attached ratchet 48 to move downward (as viewed in FIG. 16).
This downward travel of front rail assembly 26 causes pawl lever 58
to rotate about arc of rotation D against the biasing force of
biasing element 122. Pawl lever 58 rotates through arc of rotation
D about axis of rotation X of first pin 62 until pawl lever 58
releases from contact with teeth 52.
[0055] By allowing rotation of pawl lever 58 about arc of rotation
D in a folding motion relative to pawl link 60, an engagement
pressure between pawl lever 58 and teeth 52 is reduced for further
backward or counterclockwise rotation of pawl assembly 50 in the
direction of arc of rotation E'. Surface contact between ratchet
engaging end 84 and teeth 52 is reduced by the rounded surface of
ratchet engaging end 84 and clearance angle .omega., 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 for pawl lever 58 and rotation of
pawl lever 58 about arc of rotation D, the sound generated by pawl
lever 58 in contact with teeth 52 is reduced. This reduces the
overall operational sound level of furniture member 10 during use
of leg rest 14. The effort to release pawl lever 58 from ratchet 48
is also substantially eliminated because of the present invention's
use of a rotational connection between pawl lever 58 and pawl link
60. By allowing pawl lever 58 to rotate or fold away from the
engaged position with teeth 52 of ratchet 48, ratchet engaging end
84 rotates away from teeth 52 which is advantageous over prior
designs where disconnection from teeth 52 required a sliding motion
with inherent friction over the length of teeth 52 until complete
disengagement from teeth 52 was achieved.
[0056] Referring now generally to FIG. 17, leg rest 14 is shown in
an extended position. Further rearward or counterclockwise rotation
of furniture member 10 about arc of rotation C' and leg rest 14 in
an arc of rotation R causes pawl lever 58 to engage subsequent
teeth 52 of ratchet 48 in further engaged positions. In the engaged
positions, furniture member 10 is prevented from rocking forward or
clockwise as viewed in FIG. 17. In some aspects of the invention, a
ratchet-type detent mechanism 150 similar to detent 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, engages leg rest assembly 22 in multiple functional
stepped positions, each temporarily fixing leg rest assembly 22 in
one of the stepped positions and preventing leg rest assembly 22
from dropping down due to the leg weight of an occupant. Ratchet 48
and folding pawl assembly 50 therefore prevent rocking motion of
furniture member 10 while detent mechanism 150 retains leg rest
assembly 22 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 of seat
assembly 30, tension from straps used to mount pads or material to
seat assembly 30, and the tension provided by a biasing element 153
provided with toggle assembly 20.
[0057] Referring now to FIG. 18, linkage assembly 56 is shown in
greater detail. An adapter 154 is slidably received along drive rod
32. A swivel link 156 is coupled to adapter 154. Adapter 154 is
fastenably connected to drive rod 32 using one or more fasteners
158. A pin 160 is received in an aperture 162 of swivel link 156
and an aperture (not shown) of drive link 54. A fastener 164
retains pin 160. A distal end of drive link 54 includes an aperture
166 which receives hook 98 of pawl link 60. In addition, ratchet 48
includes raised embossments 168, 170 which receive fasteners used
to mount ratchet 48 to front rail assembly 26.
[0058] A functional correlation exists between the width F of pawl
lever 58 and a width Y of teeth 52 of ratchet 48 and the load
characteristics of actuation mechanism 12. By increasing a bearing
surface or contact area between pawl lever 58 and teeth 52, for
example by increasing both width F and width Y, a load capacity of
actuation mechanism 12 can be increased. This is beneficial to
accommodate heavier occupants of furniture member 10. A functional
correlation also exists between width F of pawl lever 58 and width
Y of teeth 52 and the acoustic characteristics of actuation
mechanism 12. For example, by increasing both width F and width Y
noise generated during use of furniture member 10 decreases for
heavier occupants.
[0059] A foldable pawl and ratchet assembly of the present
invention provides several advantages. By rotatably coupling a pawl
lever 58 to a pawl link 60, the pawl lever 58 can more easily
disengage from teeth 52 of a ratchet 48, which reduces a ratcheting
sound. The use of a polymeric material for pawl lever 58 provides a
quieter operation as pawl lever 58 ratchets over teeth 52 between
different engaged positions. The polymeric material also reduces
the sliding contact friction between the pawl lever 58 and teeth
52. A biasing element 122 continuously biases pawl lever 58 toward
an over-center contact position with pawl link 60 which allows pawl
link 60 and pawl lever 58 to transfer the weight load of the leg
rest assembly. A biasing element 68 promotes engagement of a
ratchet engaging end 84 of pawl lever 58 with teeth 52 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 the ratchet engaging end 84
of pawl lever 58 reduces contact with teeth 52 which further
assists in releasing pawl lever 58.
[0060] 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.
* * * * *