Technical field
[0001] This invention belongs to the field of furniture technology and in particular, relates
to a type of underframe of sitting/sleeping furniture.
Background of the invention
[0002] Underframe of sitting/sleeping furniture is used for sitting/sleeping type furniture,
e.g. movable reclining chair and sofa in front of TV etc. Chair can be adjusted from
sitting position to sleeping and back. On such furniture underframe, different design
modes can be used to install corresponding sitting/sleeping furniture, since such
underframe features a supporting frame, on which furniture parts such as rakers, footrest
frame, seat frame, backrest, and arm rest can be installed. For sitting furniture,
first use an adjusting/driving device to adjust such furniture parts, e.g. adjustment
of footrest for outward swaying. This is related to adjustment of sitting type furniture
using electric drive installed inside, or use of transfer of weight of the person
sitting on such furniture. Such footrest frame can be completely deflected to so-called
retracted position or a position of certain angle under the furniture. At a position
already swayed outward, the footrest frame is in front of the sitting/sleeping furniture
and basically on a straight line or curved line extending from the bearing surface.
Besides, footrest frame can be equipped with a so-called footrest frame extension
piece, which is pulled into the footrest frame at retracted position or extended from
footrest frame at extracted position.
[0003] Underframe of sitting/sleeping furniture is known from German utility model
29600282UI. For sitting furniture described in this utility model, the seat frame is part of
the parallel deflecting system and allows adjustment of the frame from sitting position
to sleeping position. In this connection, upper longitudinal deflecting rod of the
parallel deflecting system constitutes or bears the seat frame, with lower longitudinal
deflecting rod fixed on the lower structure. The footrest frame includes two guide
rails, relying on which the footrest frame can be connected to the seat frame in a
turnover mode. On such sitting/sleeping furniture, footrest frame guide rails constitute
transverse deflecting rods in front of the seat frame and these guide rails are also
hinged with lower longitudinal deflecting rod fixed at the frame side. Movement of
the seat frame from sitting position to sleeping position will cause the standstill
footrest frame (at inner position) under the seat frame to sway outward. The footrest
frame supports a footrest frame element at one side moving along the direction of
guide rail longitudinal axis, to close the footrest frame. Due to movable and telescoping
arrangement of guide rails, footrest frame related to footrest frame element stretching
distance can have different lengths. At position of footrest frame swaying inward,
footrest frame element is pulled inside, so that it can sway inward under the seat
frame. If the footrest frame is already in the sleeping position (swayed outward),
the footrest frame element can be pulled out to increase the length of the footrest
frame.
[0004] Another type of underframe of sitting/sleeping furniture is known from patent
EP2356922A1. In this underframe, rotating motion of footrest frame is linked to motion of seat
frame via a buffer unit, and status of the footrest frame at retracted position is
maintained using a supporting/retaining spring. Since the design of longitudinal deflecting
rod and vertical lever and the matching between longitudinal deflecting rod/ vertical
lever and seat frame have no sufficiently stable terminal position, from the point
of view of kinematic configuration of sitting position or sleeping position, such
additional buffer unit and supporting/retaining spring are very necessary for construction
of the parallel deflecting system of the underframe of sitting/sleeping furniture.
Change of dead weight on seat frame and footrest frame by the person sitting or sleeping
on the furniture may cause the following consequence: loading or unloading in the
scope of footrest frame will cause unintended movement of the seat frame.
Summary of the invention
[0005] Based on aforesaid prior arts, this invention proceeds to design a type of underframe
of sitting/sleeping furniture, aimed to ensure motion characteristics (prevent unintended
movement) of the underframe due to change of dead weight on seat frame and footrest
frame by the person sitting/sleeping on the furniture.
[0006] To realize this purpose, the technical scheme of this invention is described as follows:
A type of underframe of sitting/sleeping furniture, comprising a supporting frame
and a seat frame with backrest, wherein said seat frame is installed on said supporting
frame in a movable manner via a quasi-parallel deflecting system; said quasi-parallel
deflecting system consists of a supporting frame, a seat frame, a first rocker, and
a second rocker, so that seat frame can move between two terminal positions: sitting
position and sleeping position. Among them, first rocker is hinged with supporting
frame to form rear pivot, and second rocker is hinged with supporting frame to form
front pivot. Positions of said rear pivot and front pivot are such that with seat
frame at sleeping position, resultant gravity of the person is applied on seat frame
at a point behind rear pivot and front pivot along the direction of the backrest,
and with seat frame at sitting position, resultant gravity of the person is applied
on seat frame at a point in front of the rear pivot.
[0007] With the underframe moving between sitting position and sleeping position, rear pivot
near backrest and front pivot near chair end are designed and arranged on the supporting
frame for the quasi-parallel deflecting system of the seat frame, so that at sleeping
position, resultant gravity of the person is applied on backrest of seat frame behind
the pivots, and with seat frame at sitting position, resultant gravity of the person
is applied on seat frame at a point in front of the rear pivot. At sleeping position,
rockers of the quasi-parallel deflecting system constantly turn rearward along backrest
side, so that hinges on these rockers with the seat frame are behind rear pivot of
the seat frame, thereby occupying a stable terminal position. This position limiting
can be achieved by a corresponding limit stop fixed on the supporting frame. When
adjusted to the setting position, it is necessary to adjust the seat frame to a position
past the top dead center of the quasi-parallel deflecting system, and at this position,
the resultant gravity of the person sitting on the furniture will be applied at a
point in front of the rear pivot on the seat frame, thereby between the rear pivot
and the front pivot on the seat frame. Accordingly, a similar limit stop is required
here to realize the final position defined for the sitting position and with mechanic
stability. It is thereby ensured that theses two final positions do not require additional
fixing or force, such as spring tightening device or similar, to reliably maintain
fixed posture of the seat frame at these positions. In this way, slight (or more precisely
involuntary) transfer of weight of the person sitting or sleeping on the furniture
will not cause moving of the seat frame to an unwanted position. In particular, even
if additional support is provided for feet, since the footrest frame can be folded,
and this footrest frame is linked to motion of the seat frame using a familiar mode,
only slight loading will be applied on the seat frame via the footrest frame. This
may cause unwanted movement of the seat frame. The design of this invention can ensure
prevention of this situation, without affecting intended adjustment of the seat frame.
[0008] Special advantages of this invention: During adjustment between the sitting position
and the sleeping position, the seat frame of this underframe is maintained at an unstable
equilibrium state. At this time, the resultant gravity of a person sitting or sleeping
on the furniture just passes rear pivot of seat frame, and this point is the top dead
center of the quasi-parallel deflecting system about seat frame rear pivot, so that
the seat frame will normally not stay at such unstable equilibrium state, either adjusted
toward terminal point of the sleeping position or toward that of the sitting position,
finally achieving mechanic stability. Another advantage: If the sitting position and
the sleeping position constitute stable terminal position of adjustment and movement
of seat frame respectively, the positions relative to the seat frame quasi-parallel
deflecting system are limited by limit stops fixed on supporting frame respectively,
for example, these limit stops are provided on longitudinal deflecting rod of similar
fixed on the supporting frame, so that in virtue of interaction with rockers, only
some specified largest hunting angles of rockers can be realized.
[0009] Further improvement by this invention: Front transverse stay tube and rear transverse
stay tube of the seat frame are hinged and fixed via rocker to the support of the
longitudinal deflecting rods constituting quasi-parallel deflecting system. As part
of the quasi-parallel deflecting system, the seat frame is supported over its whole
length and at its terminal positions, and especially favorable introduction of force/supporting
function for the seat frame can be obtained. Members installed on the supporting frame
and rear pivot formed are located in the area under transverse stay tube at the side
of seat frame backrest. Accordingly, due to relatively long longitudinal deflecting
rod and corresponding distribution of weight (dead weight of the sitting/sleeping
furniture and weight of the user) on the seat frame and backrest, the most favorable
level transmission ratio is achieved. In this way, level transmission ratio between
front pivot and rear pivot of the seat frame is improved, so that it is not necessary
to use other aux. device (e.g. spring) to maintain mechanic safety and stability of
seat frame at two terminal positions corresponding to sitting position and sleeping
position.
[0010] The underframe of sitting/sleeping furniture of this invention can be switched between
its sitting position and sleeping position solely by transfer of the weight of the
person on such furniture, or by additional driving mechanism (preferably electric
or hydraulic driving mechanism). Besides, manual adjustment using electric device
or elastic support that adopts inflated spring.
[0011] For comfort of the sitting/sleeping person, the front pivot of seat frame is arranged
higher than the rear pivot of the seat frame. At sitting position, some seat frame
surface for sitting can be adjusted slightly rearward (inclining) along the direction
of backrest. Also, according to length of rockers and geometric shape of the quasi-parallel
deflecting system, reverse inclination of sleeping position can be increased so that
the sleeping position is more comfortable.
[0012] Further improvement by this invention: A footrest with footrest frame is configured
on the seat frame using known mode. This footrest frame can rotate about a turning
shaft basically parallel to the front transverse stay tube of the seat frame, and
the relatively distance between this footrest frame and the seat frame can be adjusted
using joggers. When these joggers and the quasi-parallel deflecting system take this
footrest to the closed position, the seat frame will be in the sitting status, and
when they take this footrest to the open position, the seat frame will be in the sleeping
status. The footrest frame is connected to the quasi-parallel deflecting system via
the joggers, which are used to deflect the footrest from retracted position (with
seat frame at sitting position) to the swayed-out (with seat frame at sleeping position).
Inside the footrest frame, a telescoping extension piece is provided and can extend
parallel to and along the footrest frame with the footrest at open status. The joggers
will only drive this extension piece for extending operation during the process of
swaying of footrest frame from inside to outside and with distance between end of
this frame and the ground exceeding a minimum value. If the lower end of the footrest
frame has not reached the lowest point, extending of the extension piece will impede
outward swaying of the footrest frame, and reduce structural height of the supporting
frame.
[0013] For this reason, in the further scheme, the extending driving device for the footrest
frame extension piece is a bent lever driving device. When the footrest is swayed
outward by a very small angle, the bent lever driving device will drive the extension
piece for very small linear extending operation. When the footrest frame performs
relatively large outward sway, the bent lever driving device will drive the whole
footrest for relatively large extending operation of the extension piece. When the
lowest point of the footrest frame exceeds the lowest point of the rotating motion
step by step, by corresponding design of the bent lever driving device, the footrest
frame extension piece will start to move accordingly. Later, through such bent lever
driving device, sufficient adjusting length of footrest frame extension piece can
be ensured for the designed lever length and rotating point, so that the footrest
frame can extend far in front of the seat frame, providing comfortable support for
feet/legs of user almost over its full length. Besides, through linear guide rails,
in particular roller guide rails, outward extending of footrest frame extension piece
can be guided. Through coordinated transfer of force on underframe of sitting/sleeping
furniture, commonly used expensive ball guide rails can be replaced by low cost roller
guide rails. On the underframe of this invention, footrest frame can be moved without
providing buffer unit or supporting/retaining spring.
Description of drawing figures
[0014] Fig.1 is an amplified illustration of members of the underframe of sitting/sleeping
furniture of this invention, with the underframe at sleeping position and showing
seat frame of drastically inclined backrest and totally turned over/extended footrest.
[0015] Fig.2 to Fig.6 illustrate the underframe of this invention during adjustment from
the sleeping position shown in Fig.1 to the sitting position, in the form of staged
plans, as well as views of the underframe in different directions.
[0016] Fig.7 is an amplified illustration of the footrest frame shown in Fig.5 at its swaying
position at some time; at this time, the footrest frame passes the lowest point.
[0017] In these figures: 1-underframe of sitting/sleeping furniture; 2-supporting frame;
3-seat frame; 4-footrest; 5-footrest frame; 6-footrest frame extension piece; 7-longitudinal
deflecting rods fixed on the supporting frame; 8-inclined strut; 9-rear pivot of seat
frame at backrest side; 10-flange; 11-mounting plate; 12-vertical pipe; 13-supporting
frame bearing fork; 14-rocker; 15-rocker; 16-limit stop; 17-mattress support spring;
18-flange used for motor adjustment; 19-seat frame hinge connecting flange; 20-turning
shaft of hinged connection of footrest frame; 21-footrest adjusting lever; 22-footrest
frame extension piece adjusting lever; 23-footrest fame extension piece support; 24-roller;
25-guiding section steel; 26-seat frame front transverse stay tube; 27-seat frame
rear transverse stay tube; 28-lever of bent lever driving device; 29-lever of bent
lever driving device; 30-lever of bent lever driving device; 31-limit stop; 32-intermediate
connecting rod; 33-front pivot of seat frame at footrest side; 34-spring; 35-turning
shaft; 36-pure rotating track of footrest; 37-superposed track of footrest
Preferred embodiment
[0018] The following provides further detailed description in combination with the drawing
figures and a preferred embodiment.
[0019] The underframe of sitting/sleeping furniture of this invention shown in the figures
is a structure without mattress and outer cover, so as to allow better understanding
of its members and functions. Basic design and functions are already known from prior
art so that only necessary description of special performance, structure necessary
for such performance, and its functions is provided here for the members used and
the matching between its geometry and functions. For other aspects, refer to known
underframe 1 of prior art. The underframe 1 of this invention is such that this underframe
along with supporting frame 2 can be adapted to different rakers, e.g. those comprising
mounting plate 11 and vertical pipe 12. Also, a seat frame 3 is provided and can hold
and/or control backrest and footrest 4 (not shown) that can be installed on flange
10. The same reference symbols have been provided for same or similar parts with same
or similar functions. The concept "front" refers to front of underframe 1 of sitting/sleeping
furniture in the scope of footrest 4, and the concept of "rear" refers to rear of
underframe 1 of sitting/sleeping furniture in the area of backrest (not shown), which
can be movable or fixed on corresponding flange 10 with respect to seat frame 3.
[0020] Underframe 1 of sitting/sleeping furniture is supported on the rakers via mounting
plates 11 and vertical pipes 12 on the base. At upper part of vertical pipe, a supporting
frame bearing fork 13 is provided. The two tubular longitudinal deflecting rods 7
on two forks 13 extend forward along the direction of footrest 4. Above longitudinal
deflecting rods 7 arranged at the two sides and fixed on supporting frame 2, it can
be seen from a complete tube frame structure that seat frame 3 is basically a rectangle.
The two longitudinal stay tubes of seat frame 3 are roughly parallel with longitudinal
deflecting rods 7, and seat frame 3 is connected to transverse stay tubes 26 and 27
at its two terminals. Seat frame 3 adopts mattress support springs 17 to constitute
a pedestal, which constitutes the mattress (not shown) of the sitting/sleeping furniture
along with underframe 1. Below the layer of seat frame 3, a tubular zigzag inclined
strut 8 can be identified from center area of rear transverse stay tube 27 to center
area of front transverse stay tube 26. This inclined strut 8 consolidates seat frame
3 and allows arrangement of two flanges 18, which can be used for electric adjustment
(not shown) of the seat frame 3.
[0021] Seat frame 3, two longitudinal deflecting rods 7, rockers 14 and 15, and intermediate
connecting rod 32 constitute a quasi-parallel deflecting system. Through this system,
seat frame 3 can be adjusted from the sleeping position shown in Fig.1 (amplified)
to the sitting position shown in Fig.6. For this purpose, longitudinal deflecting
rods 7 can be inclined forward and extended upward, and seat frame 3 along with backrest
(not shown) can be easily inclined rearward according to ergonomics and lengths of
rockers 14 and 15, while increasing inclination of seat frame 3 at sleeping position
(Fig.1) relative to that at sitting position.
[0022] The concept of quasi-parallel deflecting system indicates a modified deflecting system
as compared with purely parallel deflecting system. In this system, not only lengths
of rockers 14 and 15 can be changed, but also their geometric shape and bending. However,
in principle, basic geometric shape of quasi-parallel deflecting system remains unchanged.
[0023] In this design, relative to the two longitudinal deflecting rods 7, arrangement of
seat frame 3 can be adjusted using backrest side hinged rear pivot 9 and footrest
side hinged front pivot 33. Inside hinged pivots 9 and 33, rockers 14 and 15 can be
installed in a rotating manner, with the other end of these rockers directly hinged
to seat frame 3 or via intermediate connecting rod 32. Seat frame can rotate around
(and extend from) hinged pivots 9 and 33, and during this movement, due to lever lengths
of rockers 14 and 15, and level transmission ratio, inclination of seat frame 3 changes
from sitting position to sleeping position (i.e. increases). Adjusting movement of
seat frame 3 toward the sleeping position is limited by a front limit stop 16, which
blocks movement of rocker 15 to the right side as shown in Fig.1. Conversely, adjusting
movement of seat frame 3 toward the sitting position is limited by a backrest side
limit stop 31, which blocks movement of rocker 14 to the left side. Therefore, these
limit stops 16 and 31 define permitted scope of rotation of seat frame 3 between the
sitting position and the sleeping position.
[0024] Regarding the very favorable design of underframe 1 of sitting/sleeping furniture
of this invention, only these descriptions are provided. Due to geometrical structure
of members of this quasi-parallel deflecting system, seat frame 3 can maintain its
sleeping position or sitting position stable and unchanged without using aux. means
to control positions of pivots 9 and 33. Therefore, at sleeping position, resultant
gravity of the person sleeping on the furniture is applied along the direction of
backrest at a point on seat frame 3 behind pivots 9 and 33. Conversely, at sitting
position, resultant gravity of the person sitting on the furniture is applied on seat
frame 3 at a point in front of backrest side pivot 9. As shown in the figure, at the
sleeping position, rockers 14 and 15 of the quasi-parallel deflecting system always
turn rearward at backrest side, so that the hinges of seat frame 3 with rockers 14
and 15 are behind backrest side pivot 9 on seat frame 3, thereby occupying a stable
terminal position; in this regard, a corresponding limit stop 16 limits its position.
When adjusted to the sitting position, it is necessary to adjust seat frame 3 to a
position past top dead center of the quasi-parallel deflecting system, and at this
position, resultant gravity of the person sitting on the furniture is applied on seat
frame 3 at a point in front of backrest side pivot 9, hence acting between pivots
9 and 33 on seat frame 3. In this regard, a corresponding limit stop 31 is adopted
to define the sitting position and the terminal position of mechanic stability. Therefore,
it shall be ensured that no additional fixing or force (e.g. spring) is required at
these two terminal positions to maintain seat frame 3 at these positions. In this
way, slight (or more precisely involuntary) transfer of weight of the person sitting
or sleeping on the furniture will not cause moving of the seat frame 3 to an unwanted
position. In particular, even if additional support is provided for feet, on a footrest
4 that can be folded, since this footrest is linked to motion of the seat frame 3
using a familiar mode, only slight loading will be applied on the seat frame 3 via
the footrest 4. This may cause unwanted movement of the seat frame 3. The design of
this invention can ensure prevention of this situation, without affecting intended
adjustment of the seat frame 3.
[0025] Seat frame 3 is moved from sleeping position shown in Fig.1 and meeting Fig.2 to
the sitting position shown in Fig.6. This process is clearly identified and understood
by looking at Fig.2 to Fig.6. Therefore, these figures are not studied in details
here.
[0026] On underframe 1 of sitting/sleeping furniture, levers 21 and 22 are configured to
force transfer of movement of seat frame 3 to the footrest 4. Lever 21 and lever 22
each has a horizontal or nearly horizontal turning shaft (20 and 35), and one end
of these levers is connected to the quasi-parallel deflecting system in motion, either
directly or via one or more actuators. Lever 21 is responsible to deflect footrest
frame 5 around turning shaft 20, which is fixed on seat frame 3 via flange 19. Looking
at Fig.2 to Fig.5, footrest frame 5 moves from sitting position (Fig.6) to sleeping
position (Fig.2), extending out from under seat frame 3, with its extended position
roughly horizontal with pedestal. In the reverse process, footrest 5 turns totally
inside under seat frame 3.
[0027] Superposed on rotating motion of footrest frame 5, an extension piece 6 arranged
inside footrest frame 5 can be pulled out linearly relative to footrest frame 5, thus
extending footrest 4 compared with the length of inward turnover. To this end, a number
of rollers 24 are arranged at outer side of footrest frame 5, and on these rollers,
type C guiding section steel 25 can be guided and adjusted. Linear adjustment and
moving of footrest frame extension piece 6 is driven by a bent lever type driving
device, which comprises individual levers 28, 29, and 30. When lever 22 is used to
move seat frame 3, the driving operation adopts a basically familiar mode. For this
purpose, lever 22 and lever 29 driven by bent lever are connected together via hinged
turning shaft 35 using a matching mode not shown. In this way, to adjust seat frame
3 from sitting position (Fig.6) to sleeping position (Fig.2), you only need to just
the seat frame 3; this can both sway footrest frame 5 outward and linearly extend
extension piece 6 from the footrest frame.
[0028] Fig.7 illustrates another characteristic (amplified): Due to adoption of driving
by bent lever and its geometric dimensions and the position of gyration point of such
drive, only when footrest frame 5 reaches or passes the deepest point of track involving
the underframe during the change from sitting position to sleeping position, can linear
movement of footrest frame extension piece 6 from inside footrest frame 5 start. If
linear movement of footrest frame extension piece 6 has started earlier, it will be
necessary to increase clearance off ground of the underframe 1 of sitting/sleeping
furniture, so that the end of footrest frame extension piece 6 will not hit pedestal
during outward swaying and extending. This may cause uncomfortable seated position
or necessary limiting of footrest frame extension piece 6. Accordingly, compared with
the length that can be reached, the whole footrest 4 needs to be shortened, so does
supporting surface for legs. With driving by bent lever, under such situation, simple
adjustment of kinetic performance of footrest frame extension piece 6 is permitted,
as kinetic characteristics of driving using bent lever can be designed accordingly.
When exceeding the range of small amount of linear movement as driven by bent lever,
linear movement of the footrest frame extension piece 6 for a sufficient travel will
be permitted.
1. A type of underframe (1) of sitting/sleeping furniture, comprising a supporting frame
(2) and a seat frame (3) with backrest, wherein said seat frame (3) is installed on
said supporting frame (2) in a movable manner via a quasi-parallel deflecting system;
said quasi-parallel deflecting system consists of supporting frame (2), seat frame
(3), first rocker (14), and second rocker (15), so that seat frame (3) can move between
two terminal positions: sitting position and sleeping position. Among them, first
rocker (14) is hinged with supporting frame (2) to form rear pivot (9), and second
rocker (15) is hinged with supporting frame (2) to form front pivot (33). Positions
of said rear pivot (9) and front pivot (33) are such that with seat frame (3) at sleeping
position, resultant gravity of the person is applied on seat frame (3) at a point
behind rear pivot (9) and front pivot (33) along the direction of the backrest, and
with seat frame (3) at sitting position, resultant gravity of the person is applied
on seat frame (3) at a point in front of the rear pivot (9).
2. The underframe of sitting/sleeping furniture according to claim 1, wherein two limit
stops said (16, 31) are fixed on said supporting frame (2), to limit amplitude of
movement of said quasi-parallel deflecting system between the two terminal positions.
3. The underframe of sitting/sleeping furniture according to claim 2, wherein said supporting
frame (2) includes two longitudinal deflecting rods (7) fixed on supporting frame
(2), said limit stops (16, 31) are fixed on said longitudinal deflecting rods (7),
one end of said longitudinal deflecting rods (7) is hinged with second rocker (15)
to form front pivot (33) and second rocker (15) is then hinged with front transverse
stay tube (26) of seat frame (3), and the other end of said longitudinal deflecting
rods (7) is hinged with first rocker (14) to form rear pivot (9), with first rocker
(14) directly hinged with rear transverse stay tube (27) of seat frame (3) or via
intermediate connecting rod (32).
4. The underframe of sitting/sleeping furniture according to claim 1, wherein conversion
of said seat frame (3) between sitting position and sleeping position is realized
by transfer of weight of the person or electric/hydraulic driving mechanism or manual
adjustment.
5. The underframe of sitting/sleeping furniture according to claim 1, wherein said front
pivot (33) of said seat frame (3) is higher than said rear pivot (9) above ground.
6. The underframe of sitting/sleeping furniture according to any of claim 1 to claim
5, wherein said seat frame (3) is configured with a footrest (4) complete with a footrest
frame (5); said footrest frame (5) can sway around seat frame (3) via turning shaft
(20); said turning shaft (20) is fixed on front transverse stay tube (26) of seat
frame (3) in parallel via flange (19); said footrest frame (5) is connected to the
quasi-parallel deflecting system via jogger (21), to deflect footrest (4) from the
inward swaying position with seat frame (3) at sitting status to the outward swaying
position with seat frame (3) at sleeping status; said footrest frame (5) includes
a telescoping extension piece (6) and said jogger (21) will only drive said extension
piece (6) for extending operation during swaying of footrest frame (5) from inside
to outside and with distance of end of this frame above ground exceeding a minimum.
7. The underframe of sitting/sleeping furniture according to claim 6, wherein there are
a total of two said joggers, directly hinged with the quasi-parallel deflecting system
or via an actuator.
8. The underframe of sitting/sleeping furniture according to claim 6, wherein telescoping
of said extension piece (6) is driven by a bent lever comprising three interlocking
bars (28, 29, 30) and outward extending of said extension piece (6) is guided by a
roller guide rail.