Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
The present invention pertains to the field of folding
wall tables of the type designed to fold between a stoxage
position in which the table is vertically positioned adjacent
the wall, and a usable position in which the table extends
horizontally from the wall.
One such prior art type of folding table is shown in
U.S. Patent No. 3,866,547, issued to Guyton~ In this patent,
the end of the table nearest the wall is connected thereto
and supported by hinge arms, while the outer end is supported
by auxiliary fold-up legs. During folding to the storage
position, the outer end of the table rolls along the floor on
rollers which are provided in the table end. A disadvantage
of this type of structure is the requirement of the roller
wheels along the table end. Roller wheels eventually become
covered with grease leaking from around the axle, and dirt or
dust picked up from the floor. It is o$ course not desirable
to have grease or dirt near the table work surface, and
particularly directly in front of a person who might sit at
the end of the table. Another disadvantage of this type o$
structure is the re~uirement of a separate latch to hold the
table in its vertical storage position. The separate latch
adds another part to the cost of the table and adds another
step which must be performed in the operation of the table.
Another type o$ prior art $olding table is shown in
; U~S, Patent No. 3,730,107 issued to Bergkamp et al. In this
patent, the table or ironing board folds to the vertical
storage position by means of upper and lower hinge arms and
pivots on the table and on the wall or other supporting
structure, thus eliminating the need for roller wheels at the
end of the table. In the Bergkamp et al. structure, the
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table is held in its storage position by gravity due to a
bend in the lower arm which places the center of gravity of
the table in storage position between the back wall and the
lower pivot point of the bent arm. Unfortunately~ this type
of structure results in a total mechanism depth or thickness
which is so great as to either require a recess in the wall
to which the table is attached, or a separate box or closet- -
like structure into which the table can be folded. This is
often undesirable because of space limitations in the room or
structural limitations that prevent a recess being ~ormed
in the wall.
To overcome these and other problems, the present
invention provides a folding wall table that does not require
rollers on the table, does not require a separate latch to
hold the table in its storage position, and which folds
compactly against the wall without requiring either a storage
box protruding into the room or a recess being formed into
the wall.
In the Bergkamp et al. type of structure, the table is
held in its usable position by means of latches between the
table top and the upper hinge arms. This type of structure
has the advantage of not requiring separate support legs fox
i the outer end of the table, but it is subject to other
disadvantages. These disadvantages are overcome in a pre-
ferred embodiment of the present invention by latching the
' inner edge of the table, in its usable position, directly to
s the wall, or wall mounting plate or bracket, rather than to
the upper hinge arm, and by extending or positioning the
inner edge of the table directly adjacent the wall. This
provid~s a much more convenient and less cluttered working
surface. Also, by providing latch release means along the
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opposite or outer end of the table, ease of operation is improv-
ed, especially for larger tables. Release of the latches and
application of the folding force can then all he provided from
the same location with respect to the table.
Summary of the Invention
According to the present invention there is provided a
folding wall table adapted for attachment to a wall and capable
of easy movement between a usable position in which the table ex-
tends horizontally from the wall, and a storage position in which
it is vertically disposed with the underside of the table adja-
cent the wall. The folding wall table includes a table surface
member, and hinge means for connecting the table surface member
to a wall or other support. The hinge means include upper and
lower hinge arms and upper and lower wall pivot means for pivot-
ally connecting the upper and lower hinge arms respectively to a
wall with the pivot axis of the upper hinge arms mounted higher
than the pivot axis of the lower hinge arm. Upper and lower table
pivot means are provided for pivotally connecting the upper and
lower hinge arm means respectively to the underside of the tahle
surface member, with the pivot axis of the upper table pivot
means being positioned closer to the wall, when the table is in
its usable position than the pivot axis of the lower table pivot
means. The pivot axis of the lower table pivot means is offset
below a plane passing through the pivot axis of the upper table
pivot means and parallel with the table surface, when the table
i5 in its usable position. This offsetting provides an overcenter
resistance force which holds the table in its storage position.
The overcenter resistance force is provided by the offset table
pivot geometry and in
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compressional resilience of the lower hinge arm or lower
hinge arm table pivot while passing through the overcenter
position.
According to another aspect of the invention, the lower
hinge arm means may be intentionally made slightly longer
than strictly required by geometrical considerations so as
to preload the lower hinge arm means in the storage position
so as to enhance the overcenter resistance force~
Latch means may be provided for latching the inner
edge of the table directly to the wall, or wall mounting plate
or bracket, to stabilize the table in its usable position.
Alternatively, folding outer legs can be provided.
According to another aspect of the invention,
release means for the latch means may be provided adjacent
the outer edge of the table, so that the latches may be
released from an operator position at the end of the table.
Brief Descrlption of the Drawing
Figure 1 is a view in perspective of a preferred
embodiment of a wall table according to the present invention~
the top being removed for clarity of illustration and the
table being depicted in an intermediate position between
usable and storage positions;
Figure 2 is a rear elevational view of the table of
Figure 11 showing the table parts in a storage position;
Figure 3 is an enlarged sectional view of the table
of Figure 1 as seen from the line 3-3 of Figure 2, but
showing the table mounted on a wall in its usable position;
Figure 4 is a view similar to Figure 3~ but sho~ing
the table in its storage position;
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Figure 5 is an enlarged detailed sectional view
as seen from line 5-5 of Figure 3;
Figure 6 is an enlarged detailed sectional view
as seen from the line 6-6 of Figure 3;
Figure 7 is an enlarged detailed sectional view
of a portion of the latching mechanism seen in Figure 3;
Figure 8 is a side elevational view as seen from
the right to left of Figure 2 showing the table in its
storage position mounted on a wall;
Figures 9 and 10 are diagrammatic views illustrating
the geometry of the hinge assembly according to the present
invention; and
Figure 11 is a fragmentary side elevation view
showing the geometry of the hinge arms according to the
present invention.
Description of the Preferred Embodiment
In Figure 1, the table surface member has been
removed in order to show the other components more clearly.
The table frame is composed of a pair of side frame members
113 and 114, and a pair of end frame members 115 and 116.
These frame members are made of metal channel stock, with the
top channel leg being longer than the lower channel legs,
as also seen in Figure 6, so as to provide bolt clearance.
The frame members may be welded or otherwise secured together
to form a yenerally rectangular frame, and a plurality of bolt
or screw holes 117 are provided in the top channel legs of the
frame members for securing the table surface member. The
table surface member can be made of plywood, hardboard or
particle board with a suitable decorative surface mounted
thereto.
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A subframe comprises a pair of channel members 118
and 119, which are positioned parallel to side frame members
113 and 114, and which are welded or otherwise secured at
one end to frame member 116. Subframe channel members 118
and 119 also have bolt or screw holes 117 for securing a
table surface member. It will be understood that the table
surface member also serves to positionally secure the outer
ends of subframe channel members 118 and 119 with respect to
the main frame.
Wall mounting assembly 140 may comprise a large
rectangular plate 141 which is adapted to be bolted to a
wall by means of a plurality of bolts 142. A wall mounted
member 143, which may be a rectangular sectioned tube is
positioned beIow and parallel to plate 141, and is
connected therewith by means of a pair of vertical members
144 and 145. These vertical members can also be made of
rectangular tubes, and they may be weIded or otherwise secured
to both ~ember 143 and plate 141. Plate 141, and members
143-145 comprise the wall mounting assembly, and additional
bolts 142 can be provided in member 143, and also in members
144 and 145 if necessary, for holding the assembly to the wall.
The folding table is connected to the wall mounting
assembly by means of an upper hinge arm 130 and a lower hinge
arm 120. Upper hinge arm 130 comprises a pair of individual
arms 130a and 130b. In the preferred embodiment, these arms
are made of rectangular sectioned metal tubes. Hinge arm
130a is piVotally connected to the wall mounting assembly by
means of an upper wall pivot 131a. In the preferred embodiment,
pivot 131a is formed by a pair of tabs which are die-cut
from plate 141, then bent perpendicularly thereto. A pivot
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bolt 136 passes through holes in tabs 133 and through the
end of arm 130a to form the pivot. An identical pivot is
provided for the upper wall pivot of upper hinge arm 130b.
In the preferred embodiment a single lower hinge
arm 120 is used, although it will be appreciated that a pair
of side-by-side arms could be provided. Lower hinge arm 120
is made of rectangular sectioned metal tubing, and it is
pivoted at its lower end by means of a lower wall pivot 121.
This pivot may be formed by a pivot bolt 123 passing through
vertical members 144 and 145, and the lower end of hinge arm
120 which is positioned therebetween.
The upper ends of upper hinge arms 130a and 130b
are welded to a circular crossbar 134. Crossbar 134 extends
through holes provided in subframe channel members 118 and
119, so as to form the upper arm pivot generally designated
by reference number 132. Crossbar 134 is free to rotate,
but is otherwise constrained by subframe members 118 and 119.
The ends of crossbar 134 which extend beyond the points of
connection of upper hinge arms 130a and 130b are designated
by reference number 135. Ends 135 extend inside the channels
of side frame members 113 and 114 in close proximity to the
web portions thereof, thus preventing unwanted lateral
movement of the table.
Lower hinge arm 120 connects to the table at a lower
arm table pivot generally indicated by reference number 122.
The details of construction of this pivot are shown more
clearly in the sectional view of Figure 6. In Figure 6,
subframe channel members 118 and 119 are shown in sections, as
is table surface member 10 which is secured thereto by means
of screws. A pivot bolt 124 passes through pivot holes
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provided in both subframe channel members 118 and 119,
and is secured in place by caps 125 provided at each end.
Lower hinge arm 120 is welded to a circular tubular
pivot tube 127. Pivot tube 127 is positioned coaxially with
respect to pivot bolt 124, and is spaced in relationship
thereto by means of nylon or steel bushings 126 at each end
thereof. sushings 126 are designed to fit telescopically
into the ends of pivot tube 127, as the bushings also have
a central bore sized to accommodate pivot bolt 124. Pivotal
movement of lower hinge arm 120 with respect to the table
is accommodated by relative angular motion between bushings
126 and pivot bolt 124.
The table is shown in its vertical storage position
in Figures 4 and 8, in an intermediate position in Figure 1,
and in its horizontal or usable position in Figure 3. The
table does not require outer legs to support its outer end
but instead is maintained in its horizontal position by
latches. In th~ preferred embodiment, a pair of latch
assemblies 150a and 150b are attached to subframe channel
members 118 and 119, respectively. The latch assemblies are
identical, and one of them (150b) is shown in greater detail
in Figure 5. Latch assembly 150b includes a latch bolt or
pin 151. A pair of tabs 152 are die cut from the web portion
of the subframe channel member and are bent outwardly at a
r,ight angle. Tabs 152 have clearance holes to receive latch
bolt 151. A coil spring 153 is placed coaxially around bolt
151 between tabs 152, and is in abutment with a retaining
pin 154 which is placed through a small drill hole in bolt
151, extending outwardly on both sides. The other end of
spring 153 is in abutment with the tab 152 farthest from
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end frame member 116. In this manner, spring 153 normally
urges latch bolt 151 inwardly towards end frame member 116,
nearest the wall.
A control cable 155b is connected to the outer end
of latch bolt 151 by any suitable means, for example by
means of a ring 156 provided through a drill hole near the
end of bolt 151. As seen in Figure 11, control cables 155a
and 155b from the two latch assemblies extend beneath the
table surface outwardly to a pair of release brackets 160a,
160b positioned just inside of outer end frame member 115.
Control cables 155a and 155b are routed above crossbar
134 and pivot tube 127.
Release brackets 160a and 160b have generally flat
central portions which have a pair of slots 161 formed
therein. The release brackets are slidably secured to the
underside of the table surface members by screws 162 and
inserts 163 which fit in slots 161 and through which the
screws pass. The ends of the release brackets nearest the
outer end of the table have downturned tab portions 164 which
form release handles.
Striker plates for cooperating with latch assemblies
150a and 150b are provided in plate 141 of wall mounting
assembly 14Q. Striker plates 166a and 166b are shown in
Figures 2, 3 and 4, although they are not clearly visible
in Figure 1 because they are obscured by other structure.
The striker plates can be separate elements welded to the
wall mounting assembly, but in the preferred embodiment the
striker plates are die cut in plate 141, then bent outward
at an angle. An enlarged detail is shown in Figure 7.
Striker plate 166, after being die cut from plate 141, is
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bent out at an angle to form a ramp and a catch for latch
bolt 151. When the table is being moved to its horizontal
usable position, latch bolts 151a and 151b are brought into
contact with the ramp portions of striker plates 166a and
166b, causing retraction of the latch bolts against their
springs 153. When the table reaches its full horizontal
position, the latch bolt clears the ramp portions of the
striker plates and snaps back into the posi~ion shown in
Figure 7. In this position, the latch bolts prevent further
movement or folding of the table~
To fold the table, the latches are released by
grasping the handles 164 of rel~ease brackets 160 beneath the
table and pulling them towards the outer end of the table.
This causes retraction of the latch bolts, permitting upward
and inward movement of the table to the storage position
against the wall.
Bumpers 170 made of hard rubber or other suitable
material are secured to the underside of the table frame
members to cushion the movement of the table into the wall
during the folding operation and to bear against the wall
while the table is in that position. Bumpers 170 may be
positioned in holes provided in end frame member 115 and
subframe channel members 118 and 119 as seen in Figure 2,
but it will be understood that they may be placed in any of
the frame members or elsewhere on the tabIe.
Similarly, bumpers 171 may be provided as stops
for the table in its usable position. As seen in Figures
1 and 2, bumpers 171 may be secured to the tops of vertical
members 144 and 145 where they engage the underside of end
frame member 116. Alternatively, the bumpers could be
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placed on member 116 to engage members 144 and 145, or the
upper hinge arms 130a and 130b.
A nylon glide 172 may be positioned on the wall as
seen best in Figure 4, for engagement by the outer or lower
side of end frame member 116 during the initial stage of
movement of the table from its storage position, thereby
protecting the wall from abrasion.
As previously discussed, it is generally known in the
prior art to provide a linkage or hinge assembly connected
between a wall or support and a table or other generally
planar member, for controlling movement of the table between
a horizontal position and a vertical position against the
wall. The lengths of the upper and lower hinge arms, and the
positioning of the pivots along the wall and along the center
line of the table or other planar member can be selected to
provide the desired motion. Generally there is an infinite set
of different possible geometries which will give the desired
motion.
However, when the "correct" geometry is achieved
according to the prior art, the table will tend to swing
freely away from the wall under the influence of gravity, to
come to rest at some intermediate position. Thus, it has been
necessary in prior art devices to either provide counterbalance
or biasing springs, high pivot friction, or latch means to
hold the table in its vertical position.
The present invention intentionally modifies the
linkage geometry away from the "correct" geometry of the prior
art in a particular manner, so as to provide a linkage which
will automatically maintain the table in its stored position,
without the need for any latch, counterbalancing springs, or
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the like. The manner in which this feature is obtained
is explained as follows.
Figure 11 shows the basic geometry of the hinge linkage.
Reference number 130 indicates the upper hinge arm, and
reference number 120 designates the lower hinge arm. The
upper arm wall pivot, which is the point about which upper
hinge arm 130 may pivot, is indicated by reference number
131. Reference number 121 indicates the lower arm wall pivot.
The point, or more properly axis, about which table 110 and
upper hinge arm 130 are pivotable with respect to each other
is indicated by reference number 132. The corresponding
pivotal connection between table 110 and lower hinge arm
120 is indicated by reference number 122. The resulting
geometry can be thought of as a four bar linkage, with arm
120, arm 130, the wall or wall plate between pivots 131 and
121, and the table surface member between pivots 132 and
122 making up the four elements.
When the table is in its folded position, arms 120
and 130 and table 110 are approximately aligned in the same
plane, but insteacl of mounting table pivot points 122 and
132 in the same plane parallel to table 110, these pivot
points are intentionally offset by an amount indicated by
reference number 190 in Figures 3 and 11. Upper arm table
piVot 132 is intentionally placed higher (closer to the
table surface) than lower arm table pivot 122.
The arc travel by pivot point 132 is a circle centered
at 131, and is indicated by reference number 91. The arc
normally traveled by lower arm table pivot 122 is an arc
indicated by reference number 92, centered at pivot point
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By providing offset 190, and by making corresponding
adjustments in the lengths of the hinge arms, it is possible
to provide a built-in resistance force to hold the table in
its vertical position. The resistive force is supplied by
resilient forces in one or more of the hinge arms caused by
an overcenter condition when the table is near the storage
position.
This is better explained with the help of the diagram
of Figure 9. In Figure 9, the arms and pivots are numbered
as before, with the arms indicated only by a single straight
line. Offset 190 is exaggerated for purposes of illustration.
In Figure 9, the table is in its storage position adjacent and
parallel to the wall. For the given pivot point placement,
it is apparent that something in the linkage will have to
undergo deformation in order to unfold the table. In the
vertical position shown, pivot 122 is closer to the wall than
pivot 132. However, as the table is unfolded to its horizontal
position (rotating counterclockwise in Figures 9, 10 and 11)
pivot 122 must pass outwardly to a position beneath pivot
132, and then further outwardly on arc 92 before pivot 132
has moved Very far outwardly and downwardly on arc 91. (Of
course the wall prevents pivot 132 from moving outwardly and
downwardly ahead of pivot 122, which would otherwise result
in brin~ing the table down "upside down"~
However, the initial movement of pivots 122 outwardly
to a position approximately beneath pivot 132 will cause
binding or deformation of the linkage. Specifically, hinge
arm 130 might be stretched, hinge arm 122 might be compressed,
or table pivots 132 and 133 might be moved towards each other.
In the preferred embodiment, lower table pivot 122 is
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designed to bow by allowing resilient bending of pivot
tube 127.
As seen in Figure 6, pivoting of lower hinge arm
120 with respect to the table is accommodated by pivot tube
127, bushings 126, and pivot bolt 124 which completes the
pivotal connection to the subframe channel members. Pivot
bolt 124 is secured by the subframe channel members with
respect to any translational movement. However, pivot tube
127 is secured only at its ends, and its middle is spaced
apart from pivot bolt 124. Accordingly, pivot tube 127 is
free to flex or bow to accommodate the intentional mismatch
in the length of lower hinge arm 120, during movement through
the overcenter position. Resilient bending of pivot tube
127 holds the table secureIy against the wall in its vertical
position as explained beIow.
The overcenter resistance effect is seen further in
Figure 10. From an observation of arcs 91 and 92 it is seen
that these arcs are farthest apart close to the wall, and
they become increasingly close together as the pivots move
away from the wall. In Figure 10, a point indicated by
reference number 132c indicates the position of upper arm
table pivot 132 when the table is in the full vertical
storage position. The point indicated by reference number
122c is the position of lower arm table pivot 122 with the
table in the full vertical storage position. The offset
between these points 190 is again exaggerated for purposes
of illustration. The distance on table surface member 110
between table pivots 132 and 122 is indicated in Figures 10
and 11 by dimension A.
It will be appreciated that the shortest distance
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between point 132c and arc 92 falls at a position approxi-
mately vertically beneath point 132c, indicated by reference
number 95. It will also be appreciated that dimension A is
greater than the distance from point 132c to pivot 95. Since
the initial motion upon unfolding the table requires pivot
point 122 to move outwardly beyond pivot point 132, it is
clear that binding will result. Dimension A is allowed to
be momentarily resiliently shortened, allowing pivot point
122 to move from point 122c along arc 92. This shortening
is accommodated by flexing or bowing of pivot tube 127
as previously explained.
The above described situation would exist if a
portion of wall near the top of the table in its stored
position were cut away. In normal situations~ the top of
table 110 immediately butts into the wall when the table
is first moved away from its stored position, thus
preventing stationary rotation about point 132c while pivot
point 122 is movecl past the point of maximum resistance.
Instead, pivot point 132 is caused to move a short distance
to a point indicated by reference number 132d while pivot
122 is moving from pivot 122c to point 122d. Since the
distance between arcs 9I and 92 descreases as pivot 132 is
moved to the right, this has the effect of increasing the
mismatch in distance between dimension A and the shortest dis-
tance to arc 92. In this case, the point 95 would be shifted
somewhat to the right. Thus, the effect of the top end of
the table butting against the wall is to increase the
overcenter resistance effect somewhat.
After moving past the point of maximum deflection,
table pivot 122 comes to position 122d while table pivot
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132 comes to position 132d. In this position, table pivot
122 is back on arc 92, and from this point on while lowering
the table both pivots 122 and 132 can proceed outwardly and
downwardly on arcs 92 and 91 respectively, with the angular
positioning of the table moving as controlled by the geometry.
If a greater degree of overcenter resistance force
is needed, the lower hinge arm 120 can be lengthened slightly.
This has the effect of preloading the resilient pivot tube
127, so as to provide a greater resistance force. Also,
lower arm wall pivot 121 can be moved slightly outwardly
from the wall to increase th~ resistance force. In the
preferred embodiment, the overcenter compression forces are
not fully relaxed when the table is in the storage position
against the wall. A residual force is therefore maintained
for holding the table firmly against the wall, and preventing
it from sagging.
One successful embodiment of the table of Figures
11-18 uses the following set of critical dimensions: The
length of upper hinge arm 130 from pivot center to pivot
center was 12 1/2 inches. The corresponding length of lower
hinge arm 120 was 23 11/16 inches. Table pivots 122 and 132
were 4 1/4 inches apart in a direction paralleI to the table
surface, and 1/4 inch offset (dimension 190) in a direction
perpendicular to the table top. With the table in its usable
position, pivot 132 is approximately 15/16 of an inch higher
than upper wall pivot 131. In this embodiment upper wall
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pivot 131 may extend outwardly from the wall approximately
3/16 of an inch further than lower wall pivot 121, although
this dimension is not believed to be as critical so long as
wall pivots 121 and 13I remain generally equally spaced
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outwardly from the wall.
From the preceding description it will be apparent
that the present invention provides a folding wall table
that is easy to fold and unfold, and provides a large and
uncluttered work space. The table folds flat against a wall
when not in use, and is held there by an overcenter resistance
force. It is held securely in its usable position by latches
connected to the wall or wall mounting plate.
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