Office Chair Arm Assembly
Field of the Invention
The present invention relates to office chairs and in particular to an office chair arm assembly and mechanism for adjusting such an arm.
Background of the Invention
Office chairs are typically provided with arms, and in most cases these arms are adjustable. In fact, the European Union standard EN1355-1 (the standard) for office work chairs sets out a standard to which all office chairs sold within the EU should be manufactured. Part 1 of the standard provides ergonomic guidelines for the adjustability of an office chair. To comply with these requirements the pad on top of the arm should be of a minimum size, conform to a position on the chair relative to the chair back and adjust in height relative to the chair seat, and must provide for movement of the arm rest pads sideways with respect to the chair seat. The standard specifies that the adjustable clear distance between a pair of arm rest pads must be at least 100mm, whilst a rectangle a width of 50mm and a length of 150mm must remain within the perimeter of the arm rest pad as the pad position is adjusted. Vertical height adjustment of the arm relative to the seat should also be greater than 100mm.
Chairs which provide for movement of the arm sideways relative to the chair seat are known, as are chairs which provide for height adjustment of the chair arm.
US2022/0080602 describes an adjustable armrest for use by a surgeon undertaking robotic remote surgery. An armrest portion is rotatable and a locking mechanism comprises a cam having notches or grooves that may be engaged by detents to lock the armrest position.
US2011/0248542 describes an armrest assembly for a chair in which the height of the armrest can be adjusted. A locking protrusion and a number of locking grooves are arranged vertically. The locking mechanism includes a control knob underneath the armrest which connects to an elongate rod. The locking protrusion sits in an L-shaped slot in the elongate rod. Pulling upwards on the control knob causes the locking protrusion to move out of engagement with the locking groove, unlocking the arm position. The user can then manually adjust the height of the arm, releasing the control knob when the desired height is achieved. Releasing the control knob pushes the locking protrusion into an adjacent locking groove, locking the armrest at that height. US 6,974,189 describes a vertically adjustable armrest assembly comprising an operating rod with a handle located adjacent the armrest cover; a locking block and a notched plate including a number of openings. Movement of the rod in a vertical direction, via the handle, causes the locking block to move horizontally into and out of the openings on the notched plate. When the locking block is moved away from the notched plate the arm is free to move vertically, allowing the armrest height to be adjusted by lifting or depressing the armrest cover.
US10537176 describes armrests which have a height-adjustable column, along with arm supports which are rotationally adjustable.
It would be desirable to provide an armrest for an office chair that provides for adjustment of the position of the armrest in both the vertical and horizontal planes, that can be locked in multiple positions within its range of adjustment with controls positioned for ease of access to the user, and which conforms to the ergonomic guidelines of EN1335-1.
Summary of the Invention
According to a first aspect of the invention there is provided an office chair arm assembly comprising an arm rest pad and an arm rest support, wherein the arm rest pad is slidable relative to the arm rest support in a substantially vertical plane and wherein the arm rest pad is rotatable relative to the arm rest support in a substantially horizontal plane; the arm rest pad having a forward end and a rearward end; the arm rest pad mounting a locking mechanism configured to lock the arm rest pad in a selected position between a fully inward and a fully outward position; the locking mechanism comprising a first locking element that is mounted within the arm rest pad and slidable relative to said arm rest pad, and a second locking element that is mounted within the arm rest pad, wherein the second locking element is fixed to a support component upon which the arm rest pad is mounted for rotation in a substantially horizontal plane, wherein the arm rest pad is rotatable relative to the second locking element, a lock actuator mounted on the arm rest pad and configured to engage with the first locking element, wherein in a released condition of the actuator the first and second locking elements are engaged with each other and in an actuated condition the first locking element is disengaged from the second locking element; the support component upon which the arm rest pad is mounted rotatably is situated in a rearward portion of the arm rest pad and wherein the point of rotation of the arm rest pad relative to the support component is to the rear of the longitudinal axis of the support component.
Preferably, the first and second locking elements are each provided with teeth, the teeth engaging with each other when the actuator is in the released condition.
Advantageously, the actuator is located within an upper surface of the arm rest pad.
Preferably, a respective one of the actuator and the first locking element includes a cam and the other of said actuator and said first locking element includes a cam follower surface, wherein actuation of the said actuator causes the cam to engage with the cam follower surface causing sliding motion of the said first locking element, thereby disengaging from the second locking element.
The extent of rotation between the fully inward and a fully outward positions of the arm rest pad may be up to 40 degrees. The extent of rotation between the fully inward and a fully outward positions of the arm rest pad may be not less than 15 degrees. The extent of rotation between the fully inward and a fully outward positions of the arm rest pad may be in the range of 20 degrees to 30 degrees. In one example the extent of rotation between the fully inward and a fully outward positions of the arm rest pad is 20 degrees
The locking mechanism configured may provide multiple locked positions between the fully inward and a fully outward positions of the arm rest pad.
The arm rest pad may have a length and a width, wherein the length is greater than the width.
The width of the arm rest pad at the forward end may be greater than the width of the arm rest pad at the rearward end.
Preferably, the arm rest pad is at least 200mm long, at least 100mm wide at the forward end and at least 50mm wide at the rearward end of said arm rest pad.
Advantageously, the point of rotation of the arm rest pad is 150mm from the forward end of the arm rest pad. Preferably, the arm rest pad is moveable sideways by at least 50mm, whilst a rectangle a width of 50mm and a length of 150mm remains within the perimeter of the arm rest pad as the sideways movement of the arm rest pad is generated by rotation of the arm rest pad about said point of rotation.
The arm rest support may comprise a post attached to the arm rest pad and a casing attachable to a chair seat, wherein the post is mounted to slide within the casing.
The casing may have a bracket attached thereto, the bracket attachable to the chair seat.
The office chair arm assembly may further comprise a mechanism for selectively setting the position of the post within the casing, the mechanism comprising a sliding element and a locking element, the sliding element mounted to slide within the post and the locking element being connected to the sliding element and wherein locking element is flexible along its longitudinal axis and is fixed in its vertical position relative to the post.
The casing may comprise a plurality of vertically spaced apart openings and the said locking element may include a detent, and wherein in the locked configuration the detent engages in an opening in the post and a selected one of the plurality of vertically spaced apart openings.
The casing may comprise an outer casing sleeve and an inner casing sleeve, and wherein the plurality of vertically spaced apart openings are formed in the inner sleeve.
Preferably, the locking element includes at least one slot engaging member that engages with a slot formed in the sliding element, the slot lying at an angle that generates movement of the locking member both in the longitudinal direction of the post and laterally with respect to the longitudinal axis of the post upon sliding motion of the sliding element in the post along said longitudinal axis.
The office chair arm assembly may further comprise biasing means arranged to bias the sliding element such that the locking element is in a locked configuration.
The office chair arm assembly may further comprise a vertical position actuator mounted in the post and connected to the sliding element, wherein in a released condition the sliding element is in a position such that the locking element is in a locked configuration and in an actuated condition the sliding element is in a position such that the locking element is in an unlocked configuration. A second aspect of the invention provides an office chair seat comprising two office chair arm assemblies according to the first aspect of the invention.
A third aspect of the invention provides an office chair comprising an office chair seat according to the second aspect of the invention.
Brief Description of the Drawings
In the Drawings, which illustrate preferred embodiments of the invention, and which are by way of example:
Figure 1 is schematic representation of an office chair arm assembly;
Figure 2 is a cut away schematic representation of the office chair arm assembly illustrated in Figure 2;
Figure 3a is a schematic representation illustrating part of the adjustment mechanism of the office chair arm assembly illustrated in Figures 1 and 2 with the arm in its most outward position;
Figure 3b is a schematic representation illustrating part of the adjustment mechanism of the office chair arm assembly illustrated in Figures 1 and 2 with the arm in its most inward position;
Figure 3c is a schematic representation illustrating part of the adjustment mechanism of the office chair arm assembly illustrated in Figures 1 and 2 with the arm in an intermediate position;
Figure 3d is a schematic representation illustrating part of the adjustment mechanism of the office chair arm assembly illustrated in Figures 1 and 2 with the arm in its intermediate position with a locking mechanism in a disengaged configuration;
Figure 4a is a plan view of the office chair arm assembly illustrated in Figure 3a;
Figure 4b is a plan view of the office chair arm assembly illustrated Figure 4b;
Figure 5a is a plan view of the office chair arm assembly in its outward most position;
Figure 5b is a plan view of the office chair arm assembly in its inward most position;
Figure 6 is a schematic cut-away representation of the office chair arm assembly illustrating the mechanics for adjusting the arm’s vertical position;
Figure 7 is a schematic cross-sectional representation of the office chair arm assembly illustrating the mechanism for adjusting the arm’s vertical position in a first configuration; Figure 8 is an exploded view of the cross-sectional representation of the office chair arm assembly illustrated in Figure 7;
Figure 9 is a schematic cross-sectional representation of the office chair arm assembly illustrating the mechanism for adjusting the arm’s vertical position in a first configuration;
Figure 10 is an exploded view of the cross-sectional representation of the office chair arm assembly illustrated in Figure 9;
Figure 11 is a schematic cross-sectional illustration of the upper part of the office chair arm assembly;
Figure 12 is a schematic cross-sectional illustration of the lower part of the office chair arm assembly;
Figure 13a illustrates a chair according to the invention with the arm rest pads in an outward most position; and
Figure 13b illustrates the chair shown in Figure 13a with the arm rest pads in an inward most position.
Detailed Description of the Preferred Embodiments
Referring now to Figures 1 to 5b, an office chair arm assembly 1 comprises a bracket 2 for attachment to a chair seat (not shown) by means of fasteners passing through holes 3. A sleeve 4 is attached to the bracket 2 and extends substantially vertically The office chair arm assembly 1 includes an arm rest 6, which comprises a member 60 that is arranged to slide within the sleeve 4 on a vertical axis. An arm rest pad 6d is mounted to the member 60 by connector 60a. In use, an occupant of an office chair according to the invention may use the arm rest pad 6d to support his/her arm by resting the arm on the arm rest pad 6d.
The arm rest pad 6d is mounted on the connector 60a such that the arm rest pad 6d is pivotable with respect to the connector 60a about a fixed post 6e that extends from the connector 60a. A lower part 6d’ of the arm rest pad 6d includes a plate 6g which is attached to the connector 60a by fasteners 6h and 6f, which pass respectively through slots 6h and 6i in a lower wall of the arm rest pad 6d. Movement of the arm rest pad 6d from side to side about the fixed post 6e is limited by the side walls 6d” provided to either side of the plate 6g. As can be seen, in the outward most position of the arm rest pad 6d, shown in Figure 3a, an inner edge of the plate 6g is in contact with the inner wall 6d”, whereas when the the armrest 6d is in its inward most position, the outer edge of the plate 6g is in contact with the outer wall 6d” of the armrest 6d. In this example, the arm rest pad rotates through 20 degrees between the inward most and outward most positions.
The plate 6g is provided with a plurality of teeth 6k on the edge of the plate 6g distal from post 6e. These teeth 6k form a first part of a locking mechanism which allows an occupant of an office chair of the invention to adjust to position of the arm rest pad 6d to a selected position.
A second part of the locking mechanism is formed by a plate 61 which is mounted in the arm rest pad 6d so as to slide on an axis X-X, which is substantially in the longitudinal direction of the arm rest pad 6d. The end of the plate 61 proximate the plate 6g is provided with a series of teeth 61’, these teeth being shaped and dimensioned so as to engage with the teeth 6k of plate 6g. An actuation button 6m is mounted within a wall 6n. The button 6m is provided with protrusions 6p which engage with corresponding recesses in the wall 6n, thereby preventing rotation of the actuation button 6m relative to the wall 6n. The actuation button 6m has a cam 6q extending therefrom, the cam 6q being positioned over a cam follower surface 6r which is a part of the plate 61. As best illustrated in Figure 3d, when the actuation button 6m is depressed, the cam 6q engages with the cam follower surface 6r, causing the plate 61 to slide away from the plate 6g, thereby disengaging the teeth 61’ from the teeth 6k and allowing the arm rest pad 6d to rotate about post 6e. A spring 6m’ is positioned beneath the actuation button 6m, so that when the button 6m is released it returns to the position shown in Figure 3a to 3c. The plate 61 is also provided with a spring 61”, shown in Figure 2, which biases the plate 61 into the position shown in Figures 3a to 3c where teeth 61’ engage with teeth 6k.
Figures 5a and 5b show that when the arm rest pad 6d is in its inward most and outward most positions a rectangle 50mm wide and 150mm long is within the perimeter of the arm rest pad 6d. The shape and dimensions of the arm rest pad and the position of the connection 6e about which the arm rest pad pivots together ensure that the rectangle R remains within the perimeter of the arm rest pad 6d as the arm rest pad 6d is moved between the inward most our outward most positions.
The mechanism for adjusting the vertical position of the arm rest pad 6d will now be described with reference to Figures 6 to 10. The arm rest pad 6d is supported by and attached to an arm rest post 60. In the illustrated embodiment the above-mentioned connector 60a is a part of the post 60. The post 60 is substantially hollow, providing an internal chamber which has a closed end 61. The post 60 includes an opening 62 in a wall thereof, the opening 62 being configured to receive a part of a locking mechanism that provides for the vertical position of the arm reset pad 6d to be adjusted between a number of fixed positions.
The chamber provided by the hollow post 60 receives a number of components which provide for the selective vertical positioning of the arm rest pad 6d. First, the closed end 61 of the post 60 receives a spring 62. The spring supports a sliding element 63, the sliding element 63 having a lower wall portion 63e from which a boss 64 extends. In the illustrated example, the boss 64 sits in the spring 62. The sliding element 63 includes two spaced apart side walls 63a in which slots 63b and 63c are located. The slots 63b, 63c are spaced apart one above the other, lie parallel with each other on an angle of approximately 45 degrees to the longitudinal axis Y-Y. The side walls 63a are joined together by a front wall in which an opening is formed in the region of the slots 63b, 63c.
Referring to Figures 8a and 10 in particular, it can be seen that the slots 63b includes a recess 63b’ that in cross-section forms a part of a circle. The recess 63b’ is configured to receive a protruding part shaft 73 of a locking element 70.
The locking element 70 is mounted within the hollow chamber of the post 60 such that the locking element 70 is situated within the sliding element 63. The end of the locking element 70 proximate the arm rest pad 6d is provided with bosses 71 to each side thereof. These bosses 71 locate in holes within the connector part 60a of the hollow post and allow the locking element 70 to rotate relative to the post 60.
The lower end of the locking element 70 comprises a detent 72 extending to one side of the longitudinal axis Z-Z of the locking element 70 and a shaft 73 extending to the other side of the longitudinal axis Z-Z. The detent 72 is configured to pass through an opening 66 in the wall of post 60. The lower surface 66a of the opening 66 is sloped upwards from inside to outside. The detent 72 has an underside 72a that is sloped upwards at a corresponding angle, these correspondingly configured surfaces facilitating introduction of the detent 72 into the opening 66. The ends of shaft 73 extend to each side of the elongate locking element 70 to engage with the one of the slots 63b, 63c.
The locking element 70 is rotatable about the connection of bosses 71 to the connector part 60a so that the detent 72 may move out of and into the opening 66. The chair arm is configured such that the elongate element is biased into a configuration where the detent 72 engages with the opening 66 and an opening 40c that is aligned with the opening 66.
In order to adjust the vertical position of the arm rest pad 6d, the lever 6c is lifted upwards, pivoting about bosses 6c’, pressing downwards on part 63d of the sliding element 63, causing said sliding element 63 to move downwards within the post 60, compressing the spring 62. The locking element 70 is connected to the sliding element by means of the shaft 73. As the sliding element 63 moves downwards, the shaft 73 is first lifted from the recess 63b’ and then follows the slot 63b, thereby moving the lower part of the locking element towards the bracket 2, pulling the detent 72 out of the openings 40c and 66. The whole assembly comprising the arm rest 6 and post 60 may then be moved to a desired vertical position. When the lever 6c is released, the force of spring 62 lifts the sliding element 60 upwards. The shaft 73 slides in the angled slot 63b and the detent 72 engages first in opening 66, then in the aligned opening 40c. The sliding element 60 continues to slide upwards until the shaft 72 is received in the recess 63b’. Engagement of the shaft 72 in the recess 63b’ prevents inadvertent movement of the detent 72 relative to the openings 40c and 66.
The post 60 is held in place within the casing 4 by a sleeve 40. The sleeve 40 comprises two separate parts, a first part 40a which is inserted into the casing 4 from the arm rest pad end, the second part 41 being inserted into the casing 4 from the end of the casing 4 that is proximate the attachment bracket 2.
One side of the first part 40a of sleeve 40 extends to the protrusion 60a (described below). The second part 41 of the seven 40 provides a series of openings 40c therein which are spaced apart so as to provide a series of selectable positions of height adjustment of the arm rest pad 6d. The first part 40a further includes a collar 40d which sits on top of the casing 4.
The second part 41 of sleeve 40 includes a screw receiving portion that aligns with a hole 2a in the bracket 2. A screw 42 fastens the second part 41 of sleeve 40 to the bracket 2 thereby securing the second part 41 of the inner sleeve to the bracket, fixing the position of the second part 41 of the inner sleeve with respect to the casing 4. The second part 41 of the inner sleeve 40 comprises a protrusion 41b that engages with the inner surface of casing 4, thereby ensuring that the post 60 is held in place in the position shown in the drawings against radial movement.
The second part 41 of the inner sleeve 40 includes a part 41c which extends in the axial direction of the post 60 and engages with a protrusion 60b, which engages with an upper edge 41c of the second part 41 of the sleeve 40 to prevent axial movement of the post 60 towards the bracket 2.
Figures 13a and 13b illustrate a chair 80 according to the invention in schematic form. The requirements of EN1355-1 are shown on the two drawings. A rectangle that is 50mm wide by 150mm long is indicated by (A). It can be seen from Figures 13a and 13b that as the arm rest pads 6 are moved from the outward most position (Figure 13a) to the inward most position (Figure 13b) the rectangle remains within the perimeter of the arm rest pad 6.