Mechanism for an Extension Leaf

This application claims priority from Australian Patent Application 2024329873 (originally, Australian Patent Application 2024901370), filed 10 May 2024 and entitled “Mechanism for an extension leaf”, the entire disclosure of which is incorporated herein by way of cross-reference.

The disclosure herein relates to a mechanism for an extension leaf having two or more leaf portions that are articulated relative to one another to facilitate the leaf being reconfigured between a collapsed configuration and an extended configuration. The mechanism has been primarily developed for use with extension leaves of extension tables, but may also be used with extension leaves for extending other support surfaces, such as benchtops.

It is known to provide an extension table having an extension leaf comprising two leaf portions that are hinged together for movement between a folded configuration for storage and an extended configuration for deployment. An example of such an extension table is that disclosed in U.S. Pat. No. 1,766,694, the content of which is incorporated herein by way of reference, which has an extension leafcomprising an upper leaf sectionand a lower leaf sectionthat are hinged together by hinges.

A disadvantage of such a known extension table as that shown in U.S. Pat. No. 1,766,694 is that substantial manual effort is required by the user to rotate the extension leafabout pivot pinbetween its stowed, folded configuration, as shown in, and its deployed, extended configuration, during which the extension leaf passes through a partially open configuration, as shown in.

A further disadvantage of such a known extension table as that shown in U.S. Pat. No. 1,766,694 is that the weight of the leaf sections,causes the extension leafto gain momentum during the second half of its rotational movement about pivot the pinduring opening and closing and, accordingly, the second half of its opening and closing action tends to proceed in a somewhat uncontrolled manner, causing the extension leafto slam open and closed unless the user applies a significant manual braking force to reduce the momentum gained by the extension leaf. It will be appreciated that this problem is exacerbated in extension tables having heavier tabletops and therefore heavier extension leaves. The uncontrolled rotation of the extension leafduring opening and closure risks damage to components of the extension leaf and/or other components of the extension table, as well as risk of injury to the user. Attempts have been made to develop braking or damper systems for extension tables to control rotation of the extension leaves during opening and closure and thereby to ameliorate these risks. However, known braking or damper systems for extension tables tend to be complex and expensive, and tend to require components that are tailored to a particular extension leaf and not suitable for use on extension leaves of a different weight or size.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

Throughout this specification:

This Summary introduces a selection of concepts relating to this technology in a simplified form as a prelude to the Detailed Description that follows. This Summary is not intended to identify key or essential features. All combinations of the steps, features, and/or elements disclaimed are regarded as part of applicant's inventive aspects.

In some aspects, a mechanism for an extension leaf may include a frame, a force transfer component, and a damper. The frame may define: a first formation configured for engagement by an end of a first axle of the extension leaf to mount the end of the first axle for rotation about a first axis and constrain the first axle against translation in a plane perpendicular to the first axis, and a second formation defining an elongate path along the frame, the second formation being configured for engagement by an end of a second axle of the extension leaf to support the end of the second axle for rotation about a second axis and during movement of the second axle along the elongate path, a first end of the path being associated with the position of the end of the second axle when the extension leaf is in an extended configuration and an opposite, second end of the path being associated with the position of the end of the second axle when the extension leaf is in a collapsed configuration. The force transfer component may be hingedly connected to the frame about a third axis and defining an abutment surface extending across the elongate path in the frame, rotation of the force transfer component in a first direction about the third axis causing the abutment surface to move toward the first end of the path and rotation of the force transfer component in an opposite, second direction about the third axis causing the abutment surface to move toward the second end of the path, the abutment surface being configured for engagement by the end of the second axle during the movement of the second axle toward the second end of the elongate path. Further, the damper may be connected to the force transfer component to damp force applied to the force transfer component by the end of the second axle during the movement of the second axle toward the second end of the elongate path.

The damper may be a linear damper having a first end hingedly connected to the frame for rotation about a fourth axis and an opposite, second end connected to the force transfer component. The second end of the damper may be connected to the force transfer component at a location between the third axis and the abutment surface. The second end of the linear damper may be hingedly connected to the force transfer component. Alternatively, the second end of the linear damper may be cammingly connected to the force transfer component. A distance between the fourth axis and the connection between the second end of the damper and the force transfer component may gradually reduce or gradually increase during rotation of the force transfer component between a first orientation in which it extends across the elongate path at a first location along the elongate path and a second orientation in which it extends across the elongate path at the second end of the elongate path, the first location along the elongate path being between the midpoint of the elongate path and the second end of the elongate path, the gradual reduction or gradual increase in the distance actuating the linear damper via respective compression or extension thereof. The distance between the fourth axis and the connection between the second end of the damper and the force transfer component may gradually reduce or gradually increase by less than 80 percent, or in some embodiments less than 60 percent or less than 50 percent, during the rotation of the force transfer component between the first orientation and the second orientation. The distance between the fourth axis and the connection between the second end of the damper and the force transfer component may gradually reduce or gradually increase by less than 60 mm, or in some embodiments less than 50 mm or less than 35 mm, during the rotation of the force transfer component between the first orientation and the second orientation.

The damper may be configured to damp the force applied to the force transfer component by the end of the second axle during the movement of the second axle toward the second end of the elongate path from a first location along the elongate path to the second end of the elongate path, the first location along the elongate path being between the midpoint of the elongate path and the second end of the elongate path. Additionally and/or alternatively, the damper may be configured to apply an assistive force to the force transfer component during the movement of the second axle along the elongate path from the second end to a first location along the elongate path, the first location along the elongate path being between the midpoint of the elongate path and the second end of the elongate path. The force transfer component may be a lever arm.

Also disclosed herein is an extension leaf comprising the mechanism defined above and elsewhere herein, with the mechanism optionally including any one to all of the features described above and herein. Further, also disclosed is an extension table comprising the extension leaf.

Referring to the drawings, there is shown a mechanismfor an extension leafof an extension table. The mechanismcomprises a framedefining a first formationconfigured for engagement by an end of a first axleof the extension leafand second formationconfigured for engagement by an end of a second axleof the extension leaf. The first formationmounts the end of the first axlefor rotation about a first axisthat is parallel to a hinge axisof the extension leaf, and constrains the first axleagainst translation in a plane perpendicular to the first axis. In the illustrated embodiment, the first formationis simply an aperture in the frame. The second formationdefines an elongate pathalong the frame, supports the end of the second axlefor rotation about a second axis, and guides the second axlealong the elongate pathfrom endto endduring reconfiguration of the extension leafbetween its extended configuration as shown inand its collapsed configuration as shown in. In the illustrated embodiment, the second formationtakes the form of a slot in the frame. However, in other embodiments, the second formationmay, for example, comprise a flange extending from and along the frameor a channel extending along the frame.

A force transfer component, which in the illustrate embodiment takes the form of a lever arm, is hingedly connected to the frameabout a third axis. Lever armdefines an abutment surfaceextending across the elongate pathfor engagement by the end of the second axleduring the movement of the second axle toward endof the elongate path. Rotation of the lever armin a first direction about the third axiscauses the abutment surfaceto move toward endof the pathand rotation of the lever armin an opposite, second direction about the third axiscauses the abutment surfaceto move toward endof the path.

A damperis connected to the lever armto damp force applied to it when it is engaged by the end of the second axleduring the movement of the second axle toward endof the elongate path.

In the illustrated embodiment the damperis a linear damper, such as a pneumatic or hydraulic strut, having a first endhingedly connected to the framefor rotation about a fourth axisand an opposite, second endhingedly connected to the lever armat a location between the third axisand the abutment surface. In other embodiments (not shown), the second endof the damperis instead cammingly connected to the lever arm. As shown in, a distance between the fourth axisand the connection between the second endof the damperand the lever armgradually reduces during rotation of the lever arm between a first orientation, as shown in, in which it extends across the elongate path at a first locationalong the elongate pathand a second orientation, as shown in, in which it extends across the second endof the elongate path. In other embodiments (not shown), the lever armand damperare instead arranged such that the distance between the fourth axisand the connection between the second endof the damperand the lever armgradually increases during rotation of the lever arm between a first orientation. In either case, the gradual reduction or gradual increase in the distance between the fourth axisand the connection between the second endof the damperand the lever armactuates the linear damper via respective compression or extension of the damper. Moreover, in either case, the lever armand damperare ideally arranged such that the distance between the fourth axisand the connection between the second endof the damperand the lever armgradually reduces or gradually increases by less than a predetermined percentage of the original distance therebetween or a predetermined absolute amount during the rotation of the lever armbetween the orientation shown inand the orientation shown in. For example, in the embodiment illustrated in, the distance between the fourth axisand the connection between the second endof the damperand the lever armgradually reduces from 70 mm to approximately 40 mm, (i.e., by approximately 30 mm or approximately 43 percent) during the rotation of the lever armbetween the orientation shown inand the orientation shown in.

The dampermay be configured to apply an assistive force to the lever armduring the movement of the second axlealong the elongate pathfrom the second endto first location, thereby reducing the manual effort the user needs to apply to reconfigure the extension leaffrom the collapsed configuration to the extended configuration.

In the illustrated embodiment, the first axleextends from an associated bracketvia which it is connected to its respective leaf portion, and the second axleextends from an associated bracketvia which it is connected to its respective leaf portion. Also, a bearing or rolleris provided on the end of the second axleto facilitate smooth movement of the second axle along path. Also, as shown in, the mechanismhas a removable cover platethat extends over the damperand lever arm.

Whilst only mechanismfor one end of the extension leafhas been described, it will be appreciated that mechanism′ is a mirror image of mechanismand operates in the same manner as mechanism.

It will be appreciated that the mechanismprovides a number of advantages. For example, the mechanismcontrols reconfiguration of the extension leafbetween its extended and collapsed configurations, including by causing the end of the second axleto move along pathand by damping force applied to the lever armby the end of the second axleduring the movement of the second axle toward the second endof the elongate path. Such control avoids the need for the user to manually control movement of the extension leafbetween its open and closed configurations, and prevents the extension leaf from slamming open and closed, thereby ameliorating the associated risks of damage and injury. Also, transferring force between the end of the second axleand the dampervia the lever armprovides the mechanismwith a high degree of reconfigurability. For example, rather than using a different damper, the amount of damping, or assistive, force applied to the second axleby the dampercan be varied by connecting the second endof the damperto the lever armat a greater or lesser distance from the third axis. Also, the locations of the axes,, the location of the first formation, and the relative configurations of the first and second formations,, can be adjusted to cater for extension leavesof different sizes. It will also be appreciated that the mechanismhas a low profile, projecting only a small distance from the underside of the top of the extension table, such that the mechanismis relatively well concealed by the top of the extension table. It will also be appreciated that the mechanismis well suited to being motorised to provide for powered-assisted or fully powered reconfiguration of the extension leafbetween the extended and collapsed configurations.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.