Lumbar support device

A lumbar frame is arranged, movable up and down, in a lower frame through second air mats which is attached to the seat back frame of a seat to correspond to the lumbar of a person who is seated on the seat, support brackets are attached, movable forward and backward, to both ends of the lumbar frame through link mechanisms and first air mats, a lumbar support member such as the zigzag or wave-formed spring is stretched between the support brackets, and an air supply and discharge means is used to supply and discharge air to and from the air mats to adjust the lumbar support member upward, downward, forward and backward.

BACKGROUND OF THE INVENTION 
1 Field of the Invention 
The present invention relates to a lumbar support device arranged in the 
seat back of a seat within a car, for example, to support the lumbars of 
an occupant. 
2. Prior Art 
The lumbar support device disclosed in preliminarily-opened Japanese 
Utility Model Disclosure No. 59-2253 is well known as the conventional one 
which uses particularly the air mat. 
An example of this lumbar support device which uses the air mat will be 
described with reference to FIG. 1. Numeral 1 represents a seat back and 
the lumbar support device comprises zigzag springs 2 and pads 3 housed in 
the seat back 1 and three air mats 4 arranged vertically between the 
zigzag springs 2 and the pads 3. Air is selectively supplied to all, one 
or two of the three air mats 4 to adjust the position and pressure for 
supporting the lumbar of an occupant on the seat. 
When the position and pressure for supporting the lumbars of the person are 
adjusted directly by the air mats 4, however, fine adjustment cannot be 
attained and as the result, the person cannot adjust the position and 
pressure so satisfactorily as he desires. 
SUMMARY OF THE INVENTION 
A lumber support device according to the present invention comprises a 
support member for supporting the lumbars of a person sitting on the seat, 
two support brackets for supporting the support member at both ends 
thereof, a lumbar frame for freely flexibly supporting these two support 
brackets through a link mechanism, a lower frame fixed to the side frame 
of a seat back to support the lumbar frame which is movable vertically 
first air mats each interposed between the lumbar frame and each of the 
two support brackets, second air mats each interposed between the lower 
frame and the lumbar frame, and an air supply and discharge means 
connected to the first and second air mats. 
When the pressure for supporting the lumbar of a seated person is to be 
adjusted, air is supplied to or discharged from the first air mats to move 
the support member, which is supported between the lumbar frame and each 
of the two support brackets, forward and backward. When the position for 
supporting the lumbar of the seated person is to be adjusted, air is 
supplied to or discharged from the second air mats to move the lumbar 
frame, which supports the support member, up and down relative to the 
lower frame. When the support member is moved forward or backward and up 
or down in this manner by means of the first and second air mats, lumbar 
support effect can be easily attained as exact as the seated person 
desires. 
An object of the present invention is therefore to provide an improved 
lumbar support device which uses the air mats. 
Another object of the present invention is to provide a lumbar support 
device capable of easily and reliably attaining such a lumbar support 
effect as an occupant desires. 
These and other objects as well as merits of the present invention will 
become apparent from the following detailed description with reference to 
the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIG. 2, numerals 11 and 12 represent vertical side frames for a seat 
back of a seat and a lower frame 13 bridges the side frames 11 and 12 
horizontally to support the lumbars of an occupant on the seat. As shown 
in FIG. 3 (where the lower and right side represents the upper side of the 
device), four ear pieces 14, 15, 16 and 17 are located adjacent to both 
ends of the lower frame 13 and at upper and lower sides thereof and a 
lumbar frame 18 having a section of fallen U-shape is horizontally 
arranged in the lower frame 13, keeping its both semi-circularly swelled 
ends 18a and 18b interposed between the ear pieces 14 and 16 and between 
the ear pieces 15 and 17, respectively. Second air mats 20 are interposed 
between the one end 18a and the ear piece 16 and between the other end 18b 
and the ear piece 17, respectively. 
A receiving plate 21 provided with a guide pipe 21a is arranged between the 
second air mat 20 and the lumbar frame 18, inserting its guide pipe 21a 
through holes 22 provided at the end 18b of the lumbar frame 18. A pin 23 
is further passed through the ear piece 17, air mat 20, guide pipe 21a and 
ear piece 15 in this order and then fixed by a push nut 23a. The lumbar 
frame 18 is thus supported, movable up and down, in the lower frame 13. 
A pair of link mechanisms 24 is provided at each end 18a, 18b of the lumbar 
frame 18. Each link mechanism 24 comprises first and second links 31 and 
32 which are parallel links and whose one ends are pivoted on pins 27 and 
28 passed through holes 25 and 26 at one end 18b of the lumbar frame 18 
and fixed by push nuts 29 and 30, and a support bracket 37 attached to the 
other ends of the first and second links 31 and 32 by means of pins 33, 34 
and bush nuts 35, 36. 
A receiving plate 40 is attached to the other end of the first link 31 and 
a first air mat 42 is interposed between the receiving plate 40 and 
another receiving plate 41 fixed on a bottom plate 18c at one end 18b of 
the lumbar frame 18. 
The above arrangement is similarly provided at the other end 18a of the 
lumbars frame 18. 
A zigzag or wave-formed spring 43 which serves as the support member for 
supporting the lumbar of an occupant on the seat is stretched between 
support claws 37a on the support brackets 37 attached to both ends 18a and 
18b of the lumbar frame 18. 
The second and first air mats 20 and 42 for controlling the up and down 
movement and forward and backward movement of the lumbar support member 
are connected to a dual solenoid valve 47 which is formed as a unit 
provided with two 2-port, 3-position solenoid valves which can be operated 
independently from each other and each of which has a neutral position, 
through air hoses 45 and 40. The dual solenoid valve 47 is connected to an 
air pump 50 through other air hoses 48 and 49, as shown in FIG. 4. The 
dual solenoid valve 47 and the air pump 50 are connected to a control 
switch 51 through harnesses 52 and 53 while the switch 51 is connected to 
a power source 54. An air supply and discharge means is thus formed. 
The control switch 51 is provided with a lever 51a which can be swung in 
four directions, that is, up, down, forward and backward. When the lever 
51a is swung upward, for example, the air pump 50 is rendered operative 
and one part of the dual solenoid valve 47 causes the air hose 45 to be 
communicated with the air pump 50 through the air hose 48 to supply air 
into the second air mats 20. When the lever 51a is swung downward, the air 
pump 50 is stopped and air is discharged from the air mats 20. When the 
lever 51a is returned to neutral position, air supply and discharge are 
stopped. The dual solenoid valve 47 is controlled and the air pump 50 is 
rendered operative, as described above, in response to the lever 51a 
operation. The control switch 51 is located on one side of a seat back 55a 
of a car seat 55, as shown in FIG. 5. In the case of the lumbar support 
device having the above-described arrangement, its components are made 
operative as follows by the control switch 51. 
When the lever 51a of the control switch 51 is swung forward (or in a 
direction shown by an arrow 56 in FIG. 4), the air pump 50 is made 
operative while one of the dual solenoid valve 47 is controlled to cause 
the air hose 46 to be communicated with the air pump 50 through the air 
hose 49, so that air can be supplied to the first air mats 42. The link 
mechanisms 24 are thus erected to push the corrugated spring 43 stretched 
between the support brackets 37 from the spring position shown in FIG. 6 
to the spring position shown in FIG. 7 so as to support the lumbars of the 
seated person. 
When the lever 51a of the control switch 51 is swung backward (or in a 
direction reverse to the direction shown by the arrow 56), the air pump 50 
is kept inoperative while one of the dual solenoid valve 47 is controlled 
to cause the first air mats 42 to be communicated with the outside to 
discharge air from the first air mats 42. The link mechanisms 24 are then 
folded by the weight of the seated person and the flexibility of pads in 
the seat back and of the surface skin for the seat back, causing the 
spring 43 to be returned to the spring position shown in FIG. 6. 
When the lever 51a of the switch 51 is swung upward (or in a direction 
shown by an arrow 57 in FIG. 4), the air pump 50 is made operative while 
the other of the dual solenoid valve 47 is controlled to cause the air 
hose 45 to be communicated with the air pump 50 through the air hose 48 so 
as to supply air to the second air mats 20. The lumbar frame 18 is thus 
lifted to a position shown by a broken line 18d by means of the air mats 
20 causing the zigzag spring 43 to be moved upward, as shown in FIG. 8. 
When the lever 51a of the switch 51 is swung in a direction reverse to the 
direction shown by the arrow 57, the air pump 50 is kept inoperative while 
the other of the dual solenoid valve 47 is controlled to cause the second 
air mats 20 to be communicated with the outside to discharge air from the 
second air mats 20. The lumbar frame 18 comes down due to its own weight. 
Springs may be used to lower the frame 18 instead of using the weight of 
the frame 18. 
When the lever 51a of the control switch 51 is returned to neutral 
position, the device which was adjusted till then can keep its adjusted 
state. When the switch 51 is controlled and operated as described above, 
therefore, the zigzag spring 43 for supporting the lumbars of the seated 
person can be freely moved upward, downward, forward and backward. The 
person who is seated on the seat in the car can thus gain his lumbar 
support effect as easy and reliable as he can desire. 
Pantographs can be used as the link mechanisms 24 and when they are 
extended, their foremost ends do not shift in the horizontal direction but 
move in the vertical direction. Therefore, a rod, plate or the like can be 
used as the support member in addition to the zigzag spring 43. 
It may be arranged that plural zigzag springs are vertically stretched in 
the seat back frame and that they are pushed by the support member. 
Although the present invention has been described referring to its 
preferred embodiment, it should be understood that various changes and 
modifications can be made without departing from the spirit and scope of 
the present invention.