Chair with adjustable inclination

A chair includes an L-shaped backrest with a horizontal section engaged with an underside of a seat. An elongated slot is defined in an underside of the horizontal section. A spring assembly includes a knob with a screw extending through the elongated slot and threadedly engaged with the underside of the seat to thereby allow sliding movement of the screw relative to the elongated slot. A leg frame includes two arcuate legs and at least one transverse beam interconnected between the arcuate legs and received in an engaging groove in the seat and secured to two connecting rods, each connecting rod having two ends pivoted to the backrest and the seat, respectively. A a rearward pivotal movement of the backrest relative to the seat causes the seat to move upwardly and forwardly to thereby provide increased safety for the user.

BACKGROUND OF THE INVENTION 
The present invention relates to a chair with adjustable inclination to 
provided increased comfort and safety as well as easy storage. 
FIG. 7 of the drawings illustrates a conventional chair which is integrally 
formed of plastic material and includes a seat back 11', a seat 12' and 
four legs 13'. Chairs of this type can be stacked for storage. The user 
sitting on the chair may feel uncomfortable as the seat 12' and the seat 
back 11' are fixed relative to each other and thus cannot adjust the 
inclination angle therebetween. 
FIG. 8 illustrates a chair which includes a seat 23', a backrest 21' 
attached to the seat 23' by a post 22', a chassis 24', a frame 25', and a 
rod 251' connected between the seat 23' and the frame 25'. The inclination 
angle between the seat 23' and the backrest 21' is adjustable by an 
adjusting arrangement of the chassis 24' which consists of numerous 
elements and is time-consuming in assembly. In addition, the chair of this 
type cannot be stacked for storage. Further, the seat 23' cannot move 
response to inclination of the backrest 21' due to rigid connection with 
the chassis 24'. As a result, the user on the chair may fall if the 
backrest 21' is subjected to a relatively large force from the user's back 
and thus suddenly moves rearward. 
The present invention aims to overcome these difficulties and to provide an 
improved chair which mitigates and/or obviates the above problems. 
SUMMARY OF THE INVENTION 
A chair in accordance with the present invention comprises: 
a substantially L-shaped backrest including a horizontal section with an 
underside having a front end and a rear end, the underside of the 
horizontal section including a first engaging section defined in the front 
end thereof, the engaging section including a connecting plate with an 
elongated slot defined therein, the first engaging section further 
including two first guiding grooves defined therein and extending in a 
longitudinal direction of the horizontal section, 
a seat including an underside with a front end and a rear end, the rear end 
of the underside of the seat including a second engaging section for 
engaging with the first engaging section of the backrest, the rear end of 
the underside of the seat including two second guiding grooves extending 
in a longitudinal direction of the seat, the underside of the seat further 
including at least one engaging groove defined in a mediate section 
thereof, 
a spring assembly including a knob with a screw extending through the 
elongated slot in the underside of the backrest and threadedly engaged 
with the underside of the seat to thereby allow sliding movement of the 
screw relative to the elongated slot, the spring assembly further 
including a spring mounted around the screw, 
two connecting rods each having a first end received in an associated said 
first guiding groove in the backrest and pivoted to the underside of the 
backrest and a second end received in an associated said second guiding 
groove in the seat and pivoted to the underside of the seat, and 
a leg frame including two arcuate legs and at least one transverse beam 
interconnected between the arcuate legs, said at least one transverse beam 
being received in said at least one engaging groove in the seat and 
secured to the connecting rods. 
By such an arrangement, a rearward pivotal movement of the backrest 
relative to the seat causes the seat to move upwardly and forwardly to 
thereby provide increased safety for the user. 
The spring assembly may further include a cover plate mounted to and thus 
covering the connecting plate of the underside of the backrest. The cover 
plate includes a second elongated slot in alignment with the 
first-mentioned elongated slot. 
The rear end of the underside of the horizontal section of the backrest 
includes a stop for engaging with the first ends of the connecting rods to 
restrain inclination angle of the backrest. 
At least one of the arcuate legs includes a stop formed thereon. The stop 
on the leg frame of an upper chair may engage with the seat of the lower 
chair to protect the spring assembly of the upper chair from being 
damaged. 
Other objects, advantages, and novel features of the invention will become 
more apparent from the following detailed description when taken in 
conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 1 to 6 and initially to FIGS. 1 to 3, a chair in 
accordance with the present invention generally includes a backrest 1, a 
seat 2, a spring assembly 3, two connecting rods 4, and a leg frame 5. The 
backrest 1 is substantially L-shaped and includes an engaging section 11 
defined in an underside of a horizontal section thereof for engaging with 
the seat 2. The engaging section 11 includes a connecting plate 13 in 
which an elongated slot 12 is defined. A screw rod 321 of the spring 
assembly 3 is extended through the slot 12, which will be described later. 
The underside of the longitudinal section of the backrest 1 includes a 
reinforcing rib 14 and a mount piece 15 formed on each side thereof. The 
mount piece 15 includes two engaging grooves 151 extending in a 
longitudinal direction of the horizontal section for receiving the 
connecting rods 4. In addition, each rib 14 includes a hole or notch 141 
while each mount piece 15 includes a hole 152 through which a pin 16 is 
extended. A stop 17 is provided to each engaging slot 151 with which the 
associated connecting rod 4 is engagable so as to restrain the inclination 
angle of the backrest 1. 
The seat 2 includes an engaging section 22 defined in a rear end of an 
underside thereof for engaging with the engaging section 11 of the 
backrest 1. The rear end of the underside of the seat 2 further includes a 
connecting piece 21 formed on each of two sides thereof and having a hole 
or notch 211 through which the pin 16 is extended. A hollow stub 221 with 
inner threading is provided in a mediate section of the engaging section 
22 for engaging with the screw rod 321 of the spring assembly 3. Further, 
two pairs of guiding pieces 23 are provided to a front end of the 
underside of the seat 2. Each pair of guiding pieces 23 define a guiding 
groove 231 extending in a longitudinal direction of the seat 2 for 
securely receiving a portion of the associated connecting rod 4, and pins 
24 are extended through holes 232 defined in the guiding pieces 23 and the 
rods 4. The underside of the seat 2 further includes engaging plates 25 
formed on each of two sides thereof, the engaging plates 25 including 
engaging grooves 251 defined therebetween for receiving transverse beams 
51 of the leg frame 5. 
The spring assembly 3 includes a spring 31, a knob 32, and a cover plate 
33. The knob 32 includes a screw 321 formed on a end thereof, and the 
cover plate 33 is mounted to and thus covers the connecting plate 13 to 
provide an esthetically pleasing outlook and includes an elongated hole 
331 in alignment with the hole 12 in the connecting plate 13. The screw 
321 is extended through the holes 12 and 331 to engage with the stub 221 
on the underside of the seat 2, while the spring 31 is mounted around the 
screw 331 to allow the seat 1 to swivel. 
The connecting rods 4 are mounted to the underside of the seat 2 and each 
of which includes holes 41, 42 defined in two ends thereof so as to be 
pivotally connected to the backrest 1 and the seat 2, respectively. Each 
connecting rod 4 further includes a number of holes 43 defined in a 
mediate section thereof for engaging with the transverse beams 51 on the 
leg frame 5. 
The leg frame 5 includes two arcuate legs 52 connected by the transverse 
beams 51. Each transverse beam 51 includes holes 511 for engagement with 
the connecting rods 4. Each arcuate leg 52 includes a stop 53 formed 
thereon to provide increased stability when the chairs are stacked. 
Referring to FIGS. 4 and 5, when a user sits on the seat 2 with his back 
resting on the backrest 1, the backrest 1 moves from a position shown by 
phantom lines to a position shown by solid lines in FIG. 5, thereby 
providing increased comfort under the action of the spring assembly 3. In 
addition, the engaging section 11 of the backrest 1 moves upwardly and 
thus bears against the engaging section 22 of the seat 2. As a result, the 
front end of the seat 2 moves upwardly relative to the connecting rods 4, 
and the screw rod 321 is moved from first ends of the holes 12 and 331 to 
second ends of the holes 12 and 331. This provides a stable gravity for 
the user as the seat 2 moves forwardly when the backrests 1 inclines 
rearwardly. Further, the stop 17 on the backrest 1 contacts and thus 
stopped by rear ends of the connecting rods 4 to restrain the inclination 
angle of the backrest 1 which provides increased safety for the user. 
Referring to FIG. 6, the chairs constructed in accordance with the present 
invention may be stacked for convenient storage. The stops 53 on the leg 
frame 5 of an upper chair may engage with the seat 2 of the lower chair to 
protect the spring assembly 3 of the upper chair from being damaged. 
According to the above description, it is appreciated that the chair in 
accordance with the present invention may provide increased comfort for 
the user as the backrest may swivel back and forth. In addition, the seat 
may move slightly upward and forward to cause the center of gravity of the 
buttock to shift forwardly when the backrest moves rearwardly to thereby 
provide increased safety. Further, stops are provided on the backrest to 
strain inclination angle of the backrest to thereby provide increased 
safety. Further, the chairs can be stacked to minimize the storage volume, 
and stops are also provides on the leg frames to stable the stacked 
chairs. 
Although the invention has been explained in relation to its preferred 
embodiment, it is to be understood that many other possible modifications 
and variations can be made without departing from the spirit and scope of 
the invention as hereinafter claimed.