Convertible sofa mechanism

An improved three-section convertible sofa mechanism for installation in a convertible sofa. The mechanism has three sections which unfold from a sofa configuration into a bed configuration. The conversion is assisted by a motor-operated pair of bellows which assist in the lifting and positioning of the mechanism during the unfolding operation. The front edge of the convertible sofa and of the bed both deflect downwardly to eliminate the usual uncomfortable forward edge of such convertible sofas.

BACKGROUND OF THE INVENTION 
The field of the invention is convertible sofas and the invention relates 
more particularly to convertible sofa mechanisms which unfold in three 
sections from the sofa seat portion. 
Most commonly used convertible sofas utilize a foldable mattress which is 
maintained within the convertible sofa when the bed is folded into its 
couch configuration. Then when the mechanism is unfolded for use as a bed, 
the mattress is maintained on the upper surface. Unfortunately, such 
mattresses, since they need to be folded, must be thin and such 
convertible sofas are, thus, inherently uncomfortable and are only 
satisfactory for small children or for emergency use. Also, the forward 
edge of such convertible sofas, both in the folded sofa configuration or 
the extended bed configuration, have a hard forward edge which makes it 
uncomfortable to sit on the forward edge of the convertible sofa or the 
bed. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved 
three-section convertible sofa mechanism which converts into a bed having 
a mattress of full thickness and which eliminates the uncomfortable 
forward edge of the convertible sofa, both in the sofa configuration and 
in the bed configuration. 
The present invention is for an improved three-section convertible sofa 
mechanism for installation in a convertible sofa which may be forwardly 
extended to a full length bed which has a head section, a middle section 
and a foot section. The improvement comprises a base member supported on 
the floor, said member having a right side, left side, front edge and a 
back edge and having an upwardly extending support along its front edge. 
First and second inverted "J-shaped" channels are held along the right and 
left sides of the base member, respectively, and oriented so that the 
terminus of the "J" faces the front edge of the base. First and second 
main bellows members are held by the base and are adjacent to first and 
second inverted "J-shaped" channels. Each of the main bellows has a 
straight sidewardly-facing channel on its upper surface. A head section is 
held by the base above and generally parallel thereto, said head section 
having a right side, left side, front edge and a back edge. Right and left 
cam follower means are affixed to the right and left edges of the head 
section, each of the cam follower means being captured both by the 
inverted "J-shaped" channel and by one of the straight, sidewardly-facing 
channels on the upper surface of each of the bellows. Thus, when the main 
bellows is inflated, the cam follower means and their associated head 
section are carried outwardly along said straight, sidewardly-facing 
channels and upwardly, outwardly and downwardly along said "J-shaped" 
channels an extent sufficient to cause the head section to rest near its 
front edge on the upwardly extending support on the base member. A middle 
section, having a right side, a left side, a front edge and a back edge is 
hingedly affixed at its back edge to the front edge of the head section, 
and in its folded condition is supported in a parallel manner above the 
head section, said middle section having leg means affixed along the right 
and left edges at the back edge thereof. A foot section has a right side, 
a left side, front edge and a back edge and the foot section is hingedly 
affixed at its back edge to the front edge of the middle section and has 
leg means affixed along the right and left edges thereof at the front edge 
of the middle section. The foot section is moveable between a folded 
configuration where one end is parallel to and above the middle section 
and to an extended configuration when it is in line with the middle 
section. A preferred configuration of the convertible sofa has its 
outermost legs comprising a subframe which contains a pair of pivotable 
polygonal members, each member being moveable between a folded position 
and an extended position. Each polygonal member has in its folded position 
a flat base edge resting on the base member, an angled, inwardly and 
downwardly-facing edge, an angled, inwardly and upwardly-facing edge, an 
upwardly-facing slot having an inward edge and an outward edge. A pivot 
hole is positioned in the polygonal member near the outward edge of the 
slot. The polygonal member also has an angled, outward and upwardly-facing 
edge and an angled, outwardly and downwardly-facing edge. A pivot pin is 
affixed to the subframe which is affixed to the right and left edges of 
the foot section along the front edge thereof. The pivot pin fits in the 
pivot hole of the polygonal member. A support arm is affixed to the front 
edge of the foot section and positioned and shaped so that its lower end 
fits into the slot of the polygonal member and has a length about several 
inches above the lower end of the slot when no additional weight is 
exerted on the front edge of the foot section. Biasing means are held 
between the subframe and the front edge of the foot section. Each of the 
polygonal members is positioned adjacent the right and left edges of the 
subframe so that when the subframe is lifted, the polygonal member pivots 
downwardly so that its angled, outwardly and downwardly-facing edge rests 
on the adjacent edge of the subframe and the angled, inwardly and 
downwardly facing side rests on the floor, and the lower end of the 
support arm is moveable between a first position about several inches 
above the outward edge of the slot when no additional weight is exerted on 
the front edge of the foot section and the second position when it is in 
contact with the outward edge when additional weight is exerted on the 
front edge of the foot section. In this manner, the front end of the foot 
section has a biased movement when weight is exerted on it and no 
uncomfortable forward edge is present.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A convertible sofa 10 is shown in perspective view in FIG. 1 and has a 
front apron 11, a left arm 12, and a right arm 13. A pair of seat cushions 
14 and 15 rest on the bed of couch 10, and a pair of back cushions 16 and 
17 are supported along the back rest 18 of the couch. 
The novel mechanism of the present invention which is convertible from the 
sofa configuration, as shown from the exterior in FIG. 1, is shown in a 
right side view in FIG. 2. The mechanism is strapped to the couch member 
which consists of the arms and back, and the mechanism rests on a base 
member 19 which is not only supported by strap 20 but also by a plurality 
of wheels 21 which rest on floor 22 and facilitate moving the convertible 
sofa mechanism into the sofa. Wheels 21 support a bellows motor carriage 
23 which supports bellows motor 24. Wheels 21 also support a bellows 
carriage 25 upon which bellows 26 rest. A straight, sidewardly-facing 
channel 27 is affixed to the top surface of the bellows and causes a cam 
follower to ride upwardly along an inverted "J-shaped" channel 28 as 
described more particularly below. Bellows 26 preferably is wider at the 
rear thereof to increase the area of the bellows and thereby increase the 
lifting force. This shape is shown in FIG. 4. 
The manner in which bellows 26 causes the mechanism to be moved upwardly 
and outwardly is indicated best in FIG. 3 where the inverted "J-shaped" 
channel 28 captures a cam follower 29 which also passes through the 
straight, sidewardly-facing channel 27. Cam follower 29 is held by a plate 
30 which is riveted, or otherwise affixed, to frame 31 of the head section 
of the convertible sofa mechanism. The right side of frame 31 is shown in 
FIG. 3 and indicated by reference character 32. A head board 33 is 
supported by frame 31 at the back edge 34 thereof. Frame 31 is hingedly 
connected at its right and left sides near the front edge 35 to the back 
edge 36 of the middle section 37. Middle section 37 has a right edge 38 
and a front edge 39. Middle section 37 is hingedly affixed to foot section 
40 at its rear 41. The front of foot section 40 is indicated by reference 
character 42 and its right side is indicated by reference character 43. 
In assembled form, the right side of the mechanism is shown in plan view in 
FIG. 4. There it can be seen that cam follower 29 fits in the channel of 
inverted "J-shaped" channel 28 and also passes through straight channel 27 
on the top of bellows 26. It also may be seen in FIG. 3 that the inverted 
"J-shaped" channel 28 also supports a pivot pin 44 which passes through a 
hole 45 at the lower end of straight channel 27. 
Thus, returning to FIG. 2, it can be readily seen that as bellows 26 are 
being filled with air, cam follower 29 moves upwardly in the inverted 
"J-shaped" channel 28. Four positions are indicated in FIG. 2, and the 
lowermost position is indicated by reference character "1." As the bellows 
is raised to position 2, the inner middle and foot sections are all raised 
upwardly, and as the cam follower reaches position 3, and has almost 
reached its upwardmost position, and as it moves from position 3 to 
position 4, it moves forwardly and slightly downwardly where it rests on a 
second bellows 46. During this same series of movements, the head section 
has moved so that it rests at its forward edge on an upright support plate 
47. Upright support plate 47 is held by the base member 19 and is also 
supported between the left and right arms 12 and 13 by strap 20. Strap 20 
is affixed to the front apron 11 at each end thereof and encircles the 
sides and back of the convertible sofa mechanism. The convertible sofa 
mechanism is attached to the sofa arm and back frame by simply being 
stapled to the left and right arm frames and to the back frame. The 
unfolding motion is also depicted in FIG. 13 where it can be seen that the 
head section 31 is supported both by cam follower 29 and the upright 
support plate 47. After the bellows have been inflated, the middle and 
foot sections may be manually folded out. 
The left side of the mechanism has an analogous bellows, inverted 
"J-shaped" channel, and the like and functions in the same manner 
described above. Of course, a single motor 24 can supply all bellows. 
As shown in FIGS. 12 and 13, middle section 37 is supported above head 
section 31 by a cushion 48. This provides a beneficial give when one is 
sitting on the seat cushions 14 or 15 since pressure on seat cushion 14 
will also be transmitted through cushion 48 to head section 31 which is 
supported by cam follower 29. This downward movement, by compression of 
cushion 48, is further enhanced by the presence of a slot 49 in arm 50 
which is welded, or otherwise affixed, to the back edge 36 of the middle 
section. Slot 49 also holds a pin 51 in arm 52 which, likewise, has a pin 
53 which is held by arm 54 affixed near the front edge of head section 31. 
It can be seen in FIG. 14 in phantom view that as the middle and foot 
sections are folded out, that arm 50 is moved into an upright position and 
middle section 37 is aligned with head section 31. 
A leg 55 is hingedly affixed at the intersection of the middle section and 
the foot section and this hinge configuration is shown in enlarged view in 
FIG. 11. There leg 55 can be seen to have a pair of ears 56 and 57 which 
hold a pin 58 which, in turn, holds an ear 59 affixed to the middle 
section and an ear 60 affixed to the foot section. It can also be seen 
that a tongue 61 on the foot section fits into a groove 62 at the forward 
edge of the middle section. 
A plurality of slats 63 are held to the edges of the frame members by a 
plurality of springs 64 in a relatively conventional manner. The cushion 
48 is slightly narrower than the seat cushions 14 and 15 or the back 
cushions 16 and 17. This inner cushion 48 remains at the head portion of 
the bed between the arms of the couch, and its narrow width permits the 
positioning of the inverted "J-shaped" channel 28 along its side without 
rubbing. 
Another novel feature of the convertible sofa of the present invention is 
the method by which the forward edge of either the sofa or the couch is 
permitted to give in a manner similar to a soft edge couch but not usually 
possible with a convertible sofa. This downward movement is enabled, both 
in the contracted position as a convertible sofa and the extended position 
as a bed, by a novel polygonal member shown in FIGS. 5 through 10. The 
assembly is held in a subframe indicated generally by reference character 
70 which fits adjacent upright support plate 47 when the assembly is in 
its convertible sofa configuration. Then, as the bellows are inflated, 
section 70 is lifted upwardly out from behind front apron 11 and forms the 
forward leg of the bed. First, as shown in FIGS. 5 and 6, the assembly is 
shown in its couch or folded configuration where it can be seen that 
polygonal member 71 is in its upper configuration and supported by a pin 
72 and also supported by resting its base edge 73 on the floor 74 of 
subframe 70. Polygonal member 71 also has an angled, inwardly and 
downwardly-facing side 75 and an angled, inwardly and upwardly-facing side 
76. An upwardly-facing slot 77 is shaped to support a support arm 78. 
Polygonal member 71 has three flat surfaces 79, 80 and 81 which cooperate 
with surface 82 as is clear from FIGS. 8 and 9. An angled, outwardly and 
downwardly-facing side 83 has a notch 84 which contacts a pin 85 on an arm 
86 Which supports the member 70 in its lower configuration as shown in 
FIG. 7. Polygonal member 70 may have a weight 75' along side 75. 
The function of polygonal member 70 is clear from a comparison of FIGS. 6 
and 7 when the mechanism is in its convertible sofa position and the 
member is in its more upright position. It can be seen that support arm 78 
is permitted several inches of movement into the upwardly-facing slot 77 
which permits some downward movement of the forward edge of the 
convertible sofa. If sufficient pressure is provided, the bottom of 
support arm 78 will contact the base of slot 77. Once the subframe 70 is 
lifted, the floor 74 drops down an amount such that the lower dumbbell 
member 85a and the upper dumbbell member 86a contact the upper and lower 
ends of channel 87 which extends the height of subframe 70 permitting 
polygonal member to move downwardly to its position shown in FIG. 7. At 
this point, the angled, inwardly and downwardly-facing side 75 contacts 
the floor 74 of the subframe 70, but once again the edge of the bed still 
may move downwardly as indicated in FIG. 7 where now the bottom surface 88 
of support arm 82 will contact inner side 89 of slot 77. Also, surface 82 
of support arm 78 will contact surface 80 of the polygonal member 71 and, 
thus, the downward movement of the forward edge of the bed will be 
limited. As shown most clearly in FIG. 9, the outermost coil spring 90 is 
supported by a plate 91 affixed to subframe 70 and at its upper end to a 
pocket 92 in a forward plate 93. Forward plate 93 is shown in perspective 
view in FIG. 10. A spring 94 is held on a plate 95 at its lower end and in 
a pocket 96 located at the front portion 43a of right side 43 of the foot 
section. An outer spring 97 is held on a plate 98 and contacts the lower 
surface of dumbbell member 86 to permit a downward movement of the right 
edge of the assembly. 
When it is desired to reconvert the unit from its bed configuration back to 
a convertible sofa configuration, a right edge front portion 43a is 
depressed as indicated in FIG. 8, and an actuating arm 99 moves downwardly 
and its lower cam surface 100 contacts surface 81 of polygonal member 71 
moving it upwardly as indicated in FIG. 8. This same motion is transmitted 
to an analogous actuating arm 99' by a cable 101 which passes through 
guides 91a and over pulleys 102 through 104 and analogous pulleys not 
shown on the other end of the mechanism. In the event a pair of 
convertible sofa mechanisms are placed side by side as indicated in FIG. 
10 of the drawings, it would be necessary to push down on either the right 
or left outer front portion 43a or 43a' together with the front portions 
112 and 113. This returns all polygonal members to an upward position for 
its sofa configuration. 
To return the bed to its convertible sofa configuration, the foot and 
middle sections are folded back over the cushions 48 and the bed is in a 
position similar to that shown in FIG. 13. Then kick plate 104 is pushed 
back which moves arm 105 through link 106, arm 110 moving an inner valve 
107 and directing air from tube 111 into tube 108 thereby expanding second 
bellows 46. This pushes cam follower 29 first upwardly from position 4 to 
position 3 as shown in phantom lines in FIG. 2 at which point gravity 
causes bellows 26 to deflate and cam follower 29 moves downward1y along 
the straight portion of the inverted "J-shaped" channel 28 to its final 
position as shown in FIG. 2. An important feature of the present invention 
is the controlled movement of the mechanism from its bed configuration to 
its convertible sofa configuration. This is brought about by use of the 
bellows 26. At all times when the device is in its bed configuration, the 
bellows are in the position indicated by the number 4 in FIG. 2 of the 
drawings. The straight, sidewardly-facing channel 27 is in a slightly 
passed the upright orientation and is held in that position by cam 
follower 29. When the foot and middle sections have been folded back and 
second bellows 46 has been inflated to the position indicated by number 3 
in FIG. 2, the mechanism does not suddenly collapse, but instead is gently 
lowered by controlling the rate of flow out of bellows 26. This may be 
accomplished by the use of a three-way valve which in position one directs 
air from blower motor 24 to bellows 26, in a position two where it directs 
air from blower motor 24 to second bellows 46 and a third position where 
air is allowed to escape bellows 26 in a controlled manner. The 
construction of such three-way valves is conventional and, thus, not shown 
in detail in the drawings. 
Although not shown in the drawings, it is, of course, likely that a fabric 
apron will cover the subframe 70 for aesthetic reasons. It is also likely 
that attachment means such as the hook and eye configuration sold under 
the trademark, "Velcro," will be used to hold the cushions together in 
their bed configuration. 
By the use of polygonal members and the extending subframe, the front 
support of the convertible sofa assembly automatically converts from its 
compressed configuration of the convertible sofa position to an extended 
configuration in its bed mode without the necessity of any action on 
behalf of the user. Then to reconvert this sub assembly to its convertible 
sofa position, the user needs only to push downwardly on the edge (and 
center if two mechanisms are used) and the polygonal members reconvert to 
their compressed mode for use as a convertible sofa. 
As indicated in FIG. 10, a pair of mechanisms can be matched together for a 
wider couch and bed. It can also be seen that full six-inch thick cushions 
can and should be used as a mattress as indicated in FIG. 14. There it can 
be seen that the inner cushion 48 is placed at the head of the mattress, 
the back cushion 16 can be placed in the middle and the seat cushion 14 
can be placed at the foot. A preferred length for the inner cushion is 
twenty-two and three-fourths inch, twenty-seven inches is preferred for 
the back cushions and twenty-four inches for the seat cushion providing a 
total length mattress of seventy-three and three-quarter inches for a bed 
of adequate length. 
The present embodiments of this invention are thus to be considered in all 
respects a illustrative and not restrictive; the scope of the invention 
being indicated by the appended claims rather than by the foregoing 
description. All changes which come within the meaning and range of 
equivalency of the claims are intended to be embraced therein.