Abstract:
A chair with height adjustable armrests and a foldable back utilizes an engaging rod to control the height at which the armrest is positioned and a locking assembly to control the folding operation of the chair back, so that the user can adjust the height of the armrests as desired and fold the chair back for facilitating storage of the chair.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to chair parts, and more particularly to a chair with height adjustable armrests and a foldable back. 
   2. Description of the Prior Art 
   Conventional chairs are inconvenient to store since the chair back occupies large space. As a result of this, a chair with a foldable back was developed on the market, such as U.S. Pat. No. 7,311,361 entitled with “apparatus for simultaneously folding seat chair back and armrest, although such a chair is quite convenient to store since the chair back and the armrests can be simultaneously folded, its structure is relatively complex, and the height of the armrest cannot be adjusted as desired. 
   Hence, Taiwan Patent No. 086217219, entitled with “height adjusting apparatus for chair armrest” was developed in order to overcome the above problem. This technology utilizes both ends of a spring to push the cylindrical engaging portions outwards and utilizes the engaging portions to position the chair armrest, so that if the height of the chair needs adjusting, the spring will be axially compressed in such a manner that the engaging portions axially retract to disengage from the chair armrests. Obviously, the technology that a spring cooperates with a cylindrical structure to move axially is not new, but the technology of controlling the armrest position is not limited to enabling the engaging portions to move axially to position the armrests, so that the applicant of the present invention has developed a chair with height adjustable armrests and a foldable back from the angle of changing the controlling and positioning manner and simplifying the structure used for folding the chair back. 
   SUMMARY OF THE INVENTION 
   The primary objective of the present invention is to provide a chair with height adjustable armrests and a foldable back, which controls the positioning of the armrests to adjust the height of the armrests by operating a pivoting rotation of two engaging rods and utilizes a locking assembly to position the chair back, so as to enable the chair back to be pivotally folded when the chair back is released. 
   In order to achieve the above objectives, the chair comprises a chair seat assembly, a chair back and two armrests. Both sides of the chair seat assembly are pivoted to both sides of the chair back. The chair seat assembly is provided with an elastically-restorable locking assembly including an engaging protrusion. The chair back is formed with an engaging groove for cooperating with the engaging protrusion of the locking assembly of the chair seat assembly. The engaging protrusion is inserted into the engaging groove to position the chair back. The chair seat assembly includes an inserting groove at each of two opposite sides thereof. Each of the inserting grooves includes plural protruding blocks from an opening to a bottom thereof. Beneath the respective protruding blocks is defined an inserting space. The respective armrests include an inserting planar member and an elastically-restorable engaging rod. The inserting planar members of the two armrests are respectively inserted in the two inserting grooves of the chair seat assembly. Each of the engaging rods includes at one end thereof an inserting block to be inserted into one of inserting spaces in the respective inserting grooves to position the armrest. 
   If the locking assembly is operated to make the engaging protrusion disengage from the engaging groove, the chair back can be pivotally folded. If the engaging rods of the armrests are operated to pivot, the inserting block of the respective engaging rods can disengage from the inserting space to adjust the height of the armrests. The chair and the armrests can be repositioned due to the elastically-restorable function of the locking assembly and the engaging rods. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded view of a chair with height adjustable armrests and a foldable back in accordance with the present invention; 
       FIG. 2  is a perspective view of the chair with height adjustable armrests and a foldable back in accordance with the present invention; 
       FIG. 3  is a cross-sectional view showing that an armrest is positioned in the inserting groove of the chair seat assembly in accordance with the present invention; 
       FIG. 4  is a cross-sectional view showing that an inserting block disengages from the inserting space of an inserting groove in accordance with the present invention; 
       FIG. 5  is a cross-sectional view showing how the height of the armrest is adjusted in accordance with the present invention; 
       FIG. 6  is a schematic view showing that an engaging protrusion of a locking assembly is inserted in an engaging groove of the chair back in accordance with the present invention; 
       FIG. 7  is a schematic view showing that the engaging protrusion of a locking assembly is moved out of the engaging groove of the chair back in accordance with the present invention; 
       FIG. 8  is a schematic view showing the chair back in accordance with the present invention is folded; 
       FIG. 9  is a cross-sectional view of the locking assembly in accordance with the present invention; 
       FIG. 10  is a partial cross-sectional view showing that the locking assembly in accordance with the present invention is compressed; 
       FIG. 11  is an exploded view of the locking assembly in accordance with the present invention and a part of the seat which is defined with two apertures and holes for cooperating with the locking assembly; 
       FIG. 12  is a cross sectional view taken along a-a of  FIG. 9 , which shows the non-compressed state of the locking assembly in the apertures; 
       FIG. 13  is a cross sectional view taken along b-b of  FIG. 10 , which shows the compressed state of the locking assembly in the apertures; and 
       FIG. 14  is an enlarged view of a part of  FIG. 1  for showing the connection of the inserting planar member, the support board and the engaging rod. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
   Referring to  FIGS. 1-3 , a chair with height adjustable armrests and a foldable back in accordance with a preferred embodiment of the present invention comprises a chair seat assembly  10 , a chair back  20 , and two armrests  30 . 
   The chair seat assembly  10  includes a seat  11 , a leg assembly  12 , two loading members  13  and a locking assembly  14 . The leg assembly  12  is disposed at the bottom of the seat  11 , and the two loading members  13  are disposed at both sides of the seat  11 . The respective loading members  13  include an inserting groove  131  on an inner surface of which is formed plural spaced-apart protruding blocks  132 . Beneath the respective protruding blocks  132  is defined an inserting space  133 . The locking assembly  14  is an elastically-restorable assembly disposed at the rear end of the seat  11  and includes an engaging protrusion  141 . 
   Both sides of the chair back  20  are pivoted to the two loading members  13  of the chair seat assembly  10  through pivot pins A. The chair back  20  is formed with an engaging groove  121  in the bottom thereof for cooperating with the engaging protrusion  141  of the locking assembly  14  of the chair seat assembly  10 . The engaging groove  21  is provided for insertion of the engaging protrusion  141  to lock the chair back  20  to the seat in an operative position. 
   The two armrests  30  each include a support board  31 , an inserting planar member  32  and an engaging rod  33 . As shown in  FIGS. 3 and 14 , one side of the support board  31  is connected with the inserting planar member  32 , and the inserting planar member  32  of the armrest  30  is inserted into the inserting groove  131  of the loading member  13 . Each of the engaging rods  33  is L-shaped and provided with a pivoting portion  331  between both ends thereof for enabling the engaging rods  33  to be pivoted to the respective support boards  31 . Each of the engaging rods  33  is L-shaped and has one end formed with an inserting block  332  and the other end formed with a pressing block  333 . The one end of the L-shaped engaging rod  33  with the inserting block  332  has a lateral side abutted against the inserting planar member  32 . The support board  31  is provided with a longitudinal groove for accommodation of the other end of the L-shaped engaging rod  33  with the pressing block  333 , and is further defined with a transverse hole for insertion of a pin, the transverse hole is in communication with the longitudinal groove. The pivoting portion  331  takes the form of a pivot hole defined at the corner of the L-shaped engaging rod  33 , so that each of the L-shaped engaging rods  33  is pivoted to the respective support boards  31  by insertion of the pin into the pivot hole of the pivoting portion  331 . The respective pressing blocks  333  are provided with a spring  334 , and the springs  334  abut against the respective support boards  31  to make the respective engaging rods  33  pivot, so as to insert the inserting block  332  of the engaging rod  33  into one of the inserting spaces  133  of the inserting groove  131 , thus positioning the armrest  30  in the inserting groove  131 . 
   When the height of the respective armrests  30  is to be adjusted, as shown in  FIG. 4 , the user can press the pressing block  333 , so that the pressing block  333  will be forced to compress the spring  334  to make the engaging rod  33  pivot. Meanwhile, the inserting block  332  of the engaging rod  33  will disengage from the inserting space  133  of the inserting groove  131  of the loading member  13  of the chair seat assembly  10 , so that the inserting planar member  32  can move along the inserting groove  131  of the loading member  13  of the chair seat assembly  10 . As shown in  FIG. 5 , after the pressing block  333  is not pressed any longer, the spring will push the engaging rod  33  to pivot by its restoring force, so as to insert the inserting block  332  of the engaging rod  33  into another inserting space  133  of the inserting groove  131 , thus positioning the armrest  30  in the inserting groove  131  again. As a result, the height of the armrest  30  is adjusted. 
   When the chair back  20  is to be folded, as shown in  FIGS. 6-8 , the locking assembly  14  of the chair seat assembly  10  is operated to move the engaging protrusion  141  of the locking assembly  14  out of the engaging groove  21  of the chair back  20 , so that the chair back  20  can disengage from the chair seat assembly  10 , and then the chair back  20  will be pivoted relative to the chair seat assembly  10  in a folding manner. The elastically restorable structure of the locking assembly  14  is shown in  FIGS. 9-13  in detail. The seat  11  of the chair seat assembly  10  includes two holes  111  and two apertures  112  which are located at the edge of the seat  11  corresponding to the locking assembly  14  in such a manner that the holes  111  are located at the lateral side of the edge while the apertures  112  are at the top side of the edge. The locking assembly  14  includes two restricting pillars  142 , a stop surface  143  and two springs  144 . The two restricting pillars  142  of the locking assembly  14  are accommodated in the two holes  111  of the seat  11 , respectively. The springs  144  are received in the apertures  112  in such a manner that both ends of the respective springs  144  abut against the stop surface  143  and the respective apertures  112  of the seat  11  to make the locking assembly  14  move upwards and make the engaging protrusion  141  engage into the engaging groove  21  of the chair back  20 . The two restricting pillars  142  restrict the locking assembly  14  in the seat  11 . When the locking assembly  14 , as shown in  FIG. 10 , is compressed downwards, the two springs  144  will be synchronously compressed by the stop surface  143  of the locking assembly  14  to make the engaging protrusion  141  move downwards to disengage from the engaging groove  21  of the chair back  20 , so that the chair back  20  can be folded. 
   By such arrangements, not only the height of the armrests  30  of the chair can be adjusted, but the chair back  20  can be folded. 
   While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.