Lifting mechanism for a sofa bed and sofa bed

Abstract

A lifting mechanism (2) for a sofa bed (1) comprises a lever arm (50) movably connectable to a first frame (10) and a drive arm (60) engageable with the lever arm. The drive arm (60) is movable to actuate the lever arm (1). The lever arm (1) moves the first frame (10) between an elevated position corresponding to a sleeping configuration of the sofa bed and a lowered position corresponding to a seating configuration of the sofa bed. A sofa bed (1) may comprise the lifting mechanism (2), the first frame (10) configured to support a seat cushion or bed mattress, a second frame (20) connected to the first frame and a third frame (30) connected to the second frame. The third frame (30) moves relative to the second frame (20) to change the sofa bed (1) between the seating configuration and the sleeping configuration using the lifting mechanism (2).

Description

Lifting Mechanism for a Sofa Bed and Sofa BedField of the Disclosure

[0001] The disclosure relates to a lifting mechanism for a frame between two operative positions and in a particular to a lifting mechanism for a sofa bed frame. The disclosure has been developed primarily for use as a lifting mechanism for a sofa bed and will be described hereinafter by reference to this application.Background of the Disclosure

[0002] The following discussion of the prior art is intended to present the disclosure in an appropriate technical context and allow its advantages to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in this specification should not be construed as an express or implied admission that such art is widely known or forms part of common general knowledge in the field.

[0003] Sofa beds are a type of furniture in the general form of sofas or couches having an in-built foldable bed mattress underneath the seat cushions. In operation, the seat cushions are removed and the mattress is unfolded so as to convert the sofa or couch into a bed. Thus, the sofa bed offers versality in its use and compactness that benefits users, especially in smaller apartments or houses, or where an additional bed may be required on an intermittent basis.

[0004] Current sofa beds on the market are typically built in one of two ways. One way is build the sofa bed using a non-motorised fold out mattress frame with a flat sleeping surface and flat sitting surface. Another way is to build the sofa bed using a motorised fold out mattress with a flat sleeping surface and an angled sitting surface.

[0005] The second arrangement of a flat sleeping surface and angled sitting surface has been found to be the most ergonomically optimised configuration and the most comfortable for use. Hence, this arrangement has generally wider consumer acceptance and provides a preferred user experience. To date, motorised mechanisms are the only mechanisms that have been able to achieve this preferred arrangement. However, using motorised mechanisms makes the sofa bed complex and expensive to manufacture, as well as being generally less robust to damage in use.

[0006] It is an object of the present disclosure to overcome or substantially ameliorate one or more of the disadvantages of prior art, or at least to provide a useful alternative. It is an object of the disclosure in at least one preferred form to provide sofa bed that is able to provide a flat sleeping surface and angled sitting surface without a motorised mechanism that is simple and cheaper to manufacture, resistant to damage and / or easy to use.Summary of the Disclosure

[0007] A first aspect of the disclosure provides a lifting mechanism for a sofa bed, comprising: a lever arm movably connectable to a first frame of the sofa bed; and a drive arm engageable with the lever arm; wherein the drive arm is movable to actuate the lever arm; and the lever arm moves the first frame between an elevated position and a lowered position.

[0008] In one or more embodiments, the lever arm is pivotably connected to the drive arm. In one or more embodiments, the lever arm is movably connected to the first frame near or at a first end. In one or more embodiments, the lever arm is pivotably connected to the drive arm near or at a second end.

[0009] In one or more embodiments, a drive member engages the drive arm to move the drive arm into engagement with the lever arm. In one or more embodiments, the drive arm comprises a rod, beam or pipe.

[0010] In one or more embodiments, the drive arm comprises at least one stop and the drive member is engageable with the at least one stop. In one or more embodiments, the drive arm comprises a first stop and a second stop. In one or more embodiments, the drive member is movable between the first and second stops to move the first frame between the elevated and lowered positions. In one or more embodiments, the first stop is near or at a first end of the drive arm and the second stop is near or at a second end of the drive arm. In one or more embodiments, the first and second ends of the drive member are opposite each other. In one or more embodiments, the drive member engages the first stop to move the drive arm and actuate the lever arm, moving the first frame into the elevated position. In one or more embodiments, the drive member engages the second stop to move the drive arm andactuate the lever arm, moving the first frame into the lowered position. In one or more embodiments, the stops, first stop and / or second stop may comprise lands, bosses or flanges of the drive arm.

[0011] In one or more embodiments, the drive member is moveable along a first track. In one or more embodiments, the drive arm is slidable in the first track. In one or more embodiments, the drive member is moveable along the first track to cause the lever arm to pivot or rotate. In one or more embodiments, the drive member comprises a wheel. In one or more embodiments, the wheel is rotatably mounted to the drive member.

[0012] In one or more embodiments, a second frame is connected to the first frame at one end. In one or more embodiments, the second frame is pivotably connected to the first frame. In one or more embodiments, the first frame in the elevated position is substantially parallel to the second frame. In one or more embodiments, one end of the first frame is higher than the other in the lowered position. In one or more embodiments, the first frame in the lowered position defines an acute angle with the second frame.

[0013] In one or more embodiments, the second frame comprises at least a first frame member and a second frame member spaced apart from each other. In one or more embodiments, the first frame member and second frame member are substantially parallel to each other.

[0014] In one or more embodiments, the first track is formed in the second frame. In one or more embodiments, the first track is formed in at least one of the first and second frame members of the second frame. In one or more embodiments, the first track is formed in the second frame member of the second frame.

[0015] In one or more embodiments, the lever arm is connected to the second frame. In one or more embodiments, the lever arm is moveably connected to the second frame. In one or more embodiments, the lever arm is rotatably connected to the second frame about a fulcrum or pivot point located on the second frame. In one or more embodiments, the fulcrum or pivot point is located on the first frame member of the second frame. In one or more embodiments, the distance from the fulcrum to one (preferably first) end of the lever arm is less than the distance from the fulcrum to the other (preferably second) end of the lever arm. In one or more embodiments, thefulcrum or pivot point is located closer to the first frame than the second frame member of the second frame.

[0016] In one or more embodiments, a biasing mechanism connects the lever arm to the second frame for biasing the lever arm to move the first frame into the elevated position. In one or more embodiments, the biasing mechanism connected between the lever arm and the second frame member of the second frame. In one or more embodiments, the biasing mechanism comprises a spring.

[0017] In one or more embodiments, the lever arm is movable relative to the first frame. In one or more embodiments, the first frame comprises a second track and the lever arm is movable along the second track. In one or more embodiments, the lever arm comprises a wheel for moving along the second track. In one or more embodiments, the first end of the lever arm comprises the wheel.

[0018] In one or more embodiments, the lever arm comprises a channel or slot for adjusting the distance between the first frame and the second frame and / or the acute angle between the first frame and the second frame. In one or embodiments, the second frame comprises a pin for engaging the channel or slot. In one or more embodiments, the second frame comprises a flange for mounting the pin. In one or more embodiments, the second frame member of the second frame has the pin and / or flange.

[0019] A second aspect of the disclosure provides a sofa bed, comprising: the lifting mechanism of the first aspect; wherein the first frame is configured to support a bed mattress or seating cushion; the elevated position corresponds to a sleeping configuration of the sofa bed; and the lowered position corresponds to a seating configuration of the soda bed.

[0020] In one or more embodiments, the sofa bed comprises a third frame moveable relative to the second frame. In one or more embodiments, the third frame is moveable relative to the second frame to change the sofa bed between the seating configuration and the sleeping configuration. In one or more embodiments, the third frame is configured for translational movement relative to the second frame. In one or more embodiments, the third frame is slidable relative to the second frame. In one or more embodiments, the third frame is mounted for slidable movement along the first track. Inone or more embodiments, the second frame comprises a third track and the third frame is mounted for slidable movement along the third track.

[0021] In one or more embodiments, the third frame is engageable with the drive arm for moving the lever arm. In one or more embodiments, the third frame comprises the drive member. In one or more embodiments, the third frame comprises the wheel.

[0022] One or more embodiments of the second aspect may have the features of one or more embodiments of the first aspect of the disclosure stated above, where applicable.

[0023] A third aspect of the disclosure provides a method for moving a first frame between an elevated position and a lowered positions, comprising: movably connecting a first frame to a lever arm; engaging the lever arm with a drive arm; and moving the drive arm to actuate the lever arm; and wherein movement of the lever arm causes the first frame to move between an elevated position and a lowered position.

[0024] One or more embodiments of the third aspect may have the features of one or more embodiments of the first aspect of the disclosure stated above, where applicable.

[0025] In one or more embodiments, the method comprises pivotably connecting the lever arm to the drive arm. In one or more embodiments, the method comprises pivotably connecting the lever arm to the first frame near or at a first end. In one or more embodiments, the method comprises pivotably connecting the lever arm to the drive arm near or at a second end.

[0026] In one or more embodiments, the method comprises providing a second frame is spaced apart from the first frame. In one or more embodiments, the second frame comprises at least a first frame member and a second frame member. In one or more embodiments, the method comprises arranging the first frame member and second frame member substantially parallel to each other. In one or more embodiments, the first frame in the elevated position is substantially parallel to the first frame member. In one or more embodiments, the first frame in the lowered position defines an acute angle with the first frame member.

[0027] In one or more embodiments, the method comprises moving the drive arm along a first track. In one or more embodiments, the method comprises sliding the drive arm in the first track to cause the lever arm to pivot or rotate. In one or more embodiments, the method comprises forming the first track in the second frame. In one or more embodiments, the method comprises forming the first track in at least one of the first and second frame members of the second frame. In one or more embodiments, the method comprises forming the first track in the second frame member of the second frame.

[0028] In one or more embodiments, the method comprises using a drive member to engage the drive arm for moving the drive arm into engagement with the lever arm. In one or more embodiments, the method comprises moving the drive member along the first track. In one or more embodiments, the drive member comprises a wheel. In one or more embodiments, the method comprises rotatably mounting the wheel to a drive member frame.

[0029] In one or more embodiments, the drive arm comprises at least one stop and the method comprises moving the drive member to engage with the at least one stop. In one or more embodiments, the drive arm comprises two stops and the method comprises moving the drive member to engage with the stops. In one or more embodiments, the drive arm has a first stop near or at a first end and a second stop near or at a second end, wherein the method comprises moving the drive member between the first and second stops. In one or more embodiments, the method comprises moving the drive member to engage the first stop to move the drive arm and actuate the lever arm, moving the first frame into the elevated position. In one or more embodiments, the method comprises moving the drive member to engage the second stop to move the drive arm and actuate the lever arm, moving the first frame into the lowered position.

[0030] In one or more embodiments, the method comprises connecting the lever arm to the second frame. In one or more embodiments, the method comprises moveably connecting the lever arm to the second frame. In one or more embodiments, the method comprises rotatably connecting the lever arm to the second frame about a fulcrum or pivot point located on the second frame. In one or more embodiments, the method comprises locating the fulcrum or pivot point on the first frame member of the second frame. In one or more embodiments, the method comprises locating the fulcrum or pivot point such that the distance from the fulcrum to the first end of the lever arm is less thanthe distance from the fulcrum to the second end of the lever arm. In one or more embodiments, the method comprises locating the fulcrum or pivot point such that the fulcrum or pivot point is located closer to the first frame than the second frame member of the second frame.

[0031] In one or more embodiments, the method comprises moveably connecting a biasing mechanism between the lever arm to the second frame. In one or more embodiments, the method comprises moveably connecting the biasing mechanism between the lever arm to the second frame member of the second frame.

[0032] In one or more embodiments, the method comprises moving the lever arm relative to the first frame. In one or more embodiments, the first frame comprises a second track and the method comprises moving the lever arm along the second track.

[0033] In one or more embodiments, the method comprises adjusting the distance between the first frame and the second frame. In one or more embodiments, the method comprises adjusting an acute angle between the first frame and the second frame. In one or embodiments, the method comprises providing a channel or slot in the second frame to perform the adjusting step. In one or more embodiments, the method comprises providing a pin engageable with the channel slot for performing the adjusting step. In one or more embodiments, the method comprises mounting the pin to the second frame. In one or more embodiments, the method comprises mounting the pin to the second frame member of the second frame.

[0034] A fourth aspect of the disclosure provides a method for moving a sofa bed between a seating configuration and a sleeping configuration, comprising: pivotally connecting a first frame to a lever arm; engaging the lever arm with a drive arm; moving the drive arm to actuate the lever arm; and wherein movement of the lever arm causes the first frame to move between an elevated position in the sleeping configuration and a lowered position in the seating configuration.

[0035] In one or more embodiments, the method comprises providing the sofa bed with a third frame moveable relative to the second frame. In one or more embodiments, the method comprises moving the third frame moveable relative to the second frame to change the sofa bed between the seating configuration and the sleeping configuration.In one or more embodiments, the method comprises configuring the third frame for translational movement relative to the second frame. In one or more embodiments, the method comprises sliding the third frame relative to the second frame. In one or more embodiments, the method comprises mounting the third frame for slidable movement along a third track in the second frame.

[0036] In one or more embodiments, the method comprises moving the third frame to engage the drive arm for moving the lever arm. In one or more embodiments, the method comprises providing the third frame with the drive member and / or the wheel.

[0037] One or more embodiments of the fourth aspect may have the features of one or more embodiments of the third aspect of the disclosure stated above, where applicable.

[0038] A fifth aspect of the disclosure provides a sofa bed, comprising: a first frame configured to support a bed mattress or seating cushion of the sofa bed; a second frame pivotably connected to the first frame at one end; a third frame connected to the second frame and configured for translational movement relative to the second frame to change the sofa bed between a seating configuration and a sleeping configuration; and a lifting mechanism comprising: a lever arm movably connectable to the first frame; and a drive arm engageable with the lever arm; wherein the drive arm is movable to actuate the lever arm; the lever arm moves the first frame between an elevated position corresponding to the sleeping configuration and a lowered position corresponding to the seating configuration.

[0039] In one or more embodiments, the second frame comprises a third track and the third frame is mounted for slidable movement along the third track.

[0040] One or more embodiments of the fifth aspect may have the features of one or more embodiments of the first and second aspects of the disclosure stated above, where applicable.

[0041] A sixth aspect of the disclosure provides a method for moving a sofa bed between a seating configuration and a sleeping configuration, wherein a first frame of the sofa bed moves between an elevated position corresponding to the sleeping configuration and a lowered position corresponding to the seating configuration, the method comprising: configuring the first frame to support a bed mattress or seating cushion; providing a second frame pivotably connected to the first frame at one end; configuring a third frame for translational movement relative to the second frame to change the sofa bed between the seating configuration and the sleeping configuration; movably connecting a lever arm to the first frame; engaging the lever arm with a drive arm; and moving the drive arm to actuate the lever arm; wherein movement of the lever arm causes the first frame to move between the elevated position and the lowered position.

[0042] In one or more embodiments, the method comprises mounting the third frame for slidable movement along a third track in the second frame.

[0043] One or more embodiments of the sixth aspect may have the features of one or more embodiments of the third and fourth aspects of the disclosure stated above, where applicable.

[0044] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0045] Furthermore, as used herein and unless otherwise specified, the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.Brief Description of the Drawings

[0046] Preferred embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0047] Figure 1 is a side view of a sofa bed and a lifting mechanism for the sofa bed in a lowered position according to an embodiment of the disclosure;

[0048] Figure 2 is a side view of the sofa bed and lifting mechanism of Figure 1 in an elevated position;

[0049] Figure 3A is a perspective view of the lifting mechanism and sofa bed of Figure 1 in the lowered position;

[0050] Figure 3B is a partial perspective view of a drive arm and driver member used in the lifting mechanism of Figure 3A;

[0051] Figure 3C is a partial perspective view of a lever arm used in the lifting mechanism of Figure 1 in the lowered position;

[0052] Figure 3D is a partial perspective view of the lever arm in the elevated position;

[0053] Figure 4 is a perspective view of the lifting mechanism and sofa bed of Figure1 in the elevated position;

[0054] Figure 5 is a side view of the sofa bed and lifting mechanism of Figure 4;

[0055] Figure 6 is a close up partial perspective view of the lever arm in the elevated position;

[0056] Figure 7 is a close up partial side view of the biasing mechanism used in Figure 4;

[0057] Figure 8A is a perspective view of the lifting mechanism and sofa bed of Figure 1 in the elevated position;

[0058] Figure 8B is a partial perspective view of a lever in the elevated position;

[0059] Figure 8C is a partial perspective view of a drive arm and driver member in the elevated position;

[0060] Figure 8D is a partial perspective view of the lever arm in the lowered position;

[0061] Figure 9 is a perspective view of the lifting mechanism and sofa bed of Figure1 in the lowered position;

[0062] Figure 10 is a perspective view of the lifting mechanism and sofa bed of Figure 1 in the elevated position;

[0063] Figures 11 and 12 are partial perspective views of the lever arm in the elevated position from inside and outside of a frame of the sofa bed; and

[0064] Figures 13A to 13C are schematic side views of the lever arm moving from the lowered position to the elevation position.Preferred Embodiments of the Disclosure

[0065] The present disclosure will now be described with reference to the following examples which should be considered in all respects as illustrative and non-restrictive. Although the disclosure has been described with reference to specific examples, it will be appreciated by those skilled in the art that the disclosure may be embodied in many other forms. In the Figures, corresponding features within the same embodiment or common to different embodiments have been given the same reference numerals.

[0066] Referring to Figures 1, 2, 3A and 8A, a sofa bed 1 and lifting mechanism 2 for the sofa bed are illustrated. The sofa bed in this embodiment comprises a first frame 10 for supporting a seat cushion (not shown) and / or a bed mattress (not shown); a second frame 20 pivotably connected to the first frame 10; and a third frame 30 moveable relative to the second frame.

[0067] As best shown in Figures 5 to 10, the lifting mechanism 2 comprises a lever arm 50 pivotably connectable to the first frame 10 and a drive arm 60 engageable with the lever arm. The drive arm 60 in this embodiment takes the form of a rod, but can be a beam or pipe, and is movable to actuate the lever arm 50. This causes the lever arm 50 to move the first frame 10 between an elevated position (as shown in Figures 2, 4 to 8Aand 10) and a lowered position (as best shown in Figures 1 , 3A and 9). In this embodiment, the lever arm 50 is also pivotably connected to the drive arm 60.

[0068] The elevated position generally corresponds to a sleeping configuration of the sofa bed 1, while the lowered position generally corresponds to a seating configuration of the sofa bed. In the seating configuration, the seat cushion is inclined or angled with respect to the second frame 20 by virtue of being located on the first frame 10 that is also in an angled position, as shown in Figure 1. In the sleeping configuration, the seat cushion or mattress is substantially parallel or horizontal to the second frame 20, again due to its location on the first frame 10 in a substantially horizontal position, as shown in Figure 2.

[0069] In this embodiment, the movement of the third frame 30 relative to the second frame 20 changes the sofa bed 1 between the seating configuration and the sleeping configuration, as best shown in Figures 3A and 8A. The first frame 10 in the elevated position is substantially parallel to the second frame 20 in this embodiment. The lever arm 50 is also substantially upright in the elevated position, extending transversely to the longitudinal axes of the first and second frames 10, 20, as best shown in Figures 2, 4 and 8A. In this embodiment, in the lowered position, one end 14 of the first frame 30 is higher than the other end 15, as best shown in Figures 1 and 3A. It can be seen that in the lowered position, the first frame 10 defines an angle a (which in almost all cases will be an acute angle) with the second frame 20, as best shown in Figure 1, whereas in the elevated position the angle a falls to zero. The lever arm 50 is also in at an angled position in the lowered position, generally forming an acute angle to the second frame 20.

[0070] The second frame 20 in this embodiment comprises a first frame member 22 and a second frame member 23 spaced apart from each other, and preferably arranged substantially parallel to each other, as best shown in Figures 5 and 6. A connecting plate 24 joins the first and second frame members 22, 23. The second frame 20 is connected to the first frame 10 at one end 25 via a post 17 of the first frame 10 that is hingedly or pivotably connected to the end 14, as best shown in Figures 3A and 7. The post 17 provides a pivot point 18 for the first frame 10 to move between the elevated and lowered positions. This enables the seat height to be constant while the other end 15 of the first frame 1 is raised and lowered to adjust the seat angle between the angle a in thelowered position and substantially zero (i.e. substantially horizontal or flat) in the elevated position.

[0071] In this embodiment, the third frame 30 can be stored between the first and second frames 10, 20 within the sofa bed 1 in the seating configuration and comprises an end board or plate 33. The third frame 30 comprises wheels 35 that enables the third frame to be pulled in an outward direction of the sofa bed 1 to move the sofa bed into the sleeping configuration. Preferably, the third frame 30 is configured for translational movement or slidable movement relative to the second frame 20.

[0072] A drive member in the form of the third frame 30 engages the drive arm 60 to move the drive arm and actuate the lever arm 50. In one or more embodiments, the drive member may be a component separate from the third frame 30, but is preferably operatively connected to the third frame for movement with the third frame.

[0073] The drive arm or rod 60 comprises a first stop 62 and a second stop 63, which are formed by bending the ends of the rod to form laterally extending flanges, as best shown in Figures 9 to 11. However, in other embodiments, the first and second stops may be arranged near or at opposite ends to each other on the drive arm. The stops can also take other forms, such as protrusions, lands, bosses and other projections, preferably laterally from the rod 60 but could extend at an angle to the rod. The third frame 30, acting as the drive member, is movable between the first and second flanges 62, 63 to move the first frame 10 between the elevated and lowered positions. It will be appreciated that in other embodiments, the drive arm may comprise one stop or have more than two stops, if desired. In further embodiments, there may more than one drive arm. In this case, there would be a drive arm with its own stop at opposite ends of the second frame 20, connected to each other.

[0074] As best shown in Figures 9 to 12, the second frame 20 has a track 27, preferably formed as a channel in the second frame member 23, along which the rod 60 may slidingly move as it is pushed by the third frame 30 after engagement. The channel 27 may be partly enclose the rod 60 to secure it in the second frame member 23. The partly enclosed channel 27 may be viewed as a sleeve. This results in two slots in the sleeve through which the flanges 62, 63 may extend laterally for engagement with the third frame acting as the driver member. However, in other embodiments, the channel 27 may be substantially open to allow more access to the rod 60.

[0075] The sliding movement of the rod 60 causes the lever arm 50 to pivot or rotate, and induce movement of the first frame 10 to either the elevated position or the lowered position. The third frame 30 also slidingly moves along the channel or track 27 to engage the rod 60 via its first and second flanges 62, 63. In this embodiment, the third frame 30 comprises a wheel 37 that travels along the track 27 and is preferably used to engage the flanges 62, 63 and move the rod 60 along the track or channel. The wheel 37 is rotatably mounted to the third frame 30, preferably at one corner. The wheel 37 may be viewed as part of the third frame 30 or as a separate driver member operatively connected to the third frame. Thus, the third frame 30, acting as the drive member, engages the first stop 62 on the drive arm or rod 60 to move the drive arm. This actuates the lever arm 50, moving the first frame 10 into the elevated position. Similarly, when the third frame 30, acting as the drive member, engages the second stop 62, this moves the rod 60. This in turn actuates the lever arm 50, moving the first frame 10 into the lowered position.

[0076] In other embodiments, the second frame 20 may also have a separate track or channel in which the third frame 30 may move via the wheel 37 to engage the first flange 62 or second flange of the rod 60. The separate track in these embodiments is substantially parallel to the track 27 so that the third frame 30 and rod 60 move along substantially the same path when the third frame engages the rod.

[0077] The lever arm 50 is pivotably connected to the first frame 10 near or at a first end 52, which in this embodiment is the upper end. The lever arm 50 is also pivotably connected to the drive arm 60 near or at a second end 53, which in this embodiment is the lower end. Thus, the lever arm 50, drive arm 60 and first frame 10 form a linkage arrangement, such that sufficient movement of the drive arm 60 will actuate the lever arm 50, which in turn moves the first frame 10.

[0078] The lever arm 50 is also connected to the second frame 20, and is preferably moveably connected to the second frame. In this embodiment, the lever arm 50 is rotatably connected to the second frame 20 about a fulcrum or pivot point 70 located on the second frame, preferably the first frame member 22, as best shown in Figures 5, 6, 11 and 12. The distance from the fulcrum 70 to one (preferably first or upper) end 52 of the lever arm 50 is less than the distance from the fulcrum to the other (preferably second or lower) end 53 of the lever arm. In other words, the fulcrum 70 is located closer to the first frame 10 than the second frame member 23 of the second frame 20.This arrangement of the fulcrum provides a mechanical advantage where movement of the lower end 53 of the lever arm 50 by the rod 60 causes a corresponding movement of the upper end 52 of the lever arm around the fulcrum 70. Consequently, less effort is required to pivot or rotate the lever arm 50, and thus move the first frame 10 from the lowered position to the elevated position, and vice-versa. This is illustrated in Figures 13A to 13C, discussed in more detail below.

[0079] To assist in reducing the effort required in particular to move the first frame 10 from the lowered position to the elevated position, a biasing mechanism 80 connects the lever arm 50 to the second frame 20 for biasing the lever arm towards moving the first frame 10 into the elevated position, as best shown in Figure 7. In this embodiment, the biasing mechanism 80 comprises a spring, and is preferably connected the lever arm 50 (preferably at its second or lower end 53) and the second frame member 23 of the second frame 20 via a mounting plate 83. In this arrangement, the biasing mechanism 80 pulls the lever arm 50 in a direction that causes it to move the first frame 10 into the elevated position.

[0080] In this embodiment, there is a mechanism for effectively adjusting the height of the first frame 10 and / or its acute angle relative to the second frame 20, as best shown in Figures 1 , 6 and 9 to 11. This mechanism comprises a channel or slot 90 on the lever arm 50 for adjusting the distance between the first frame 10 and the second frame 20. The channel or slot 90 may alternatively or in addition adjust the acute angle a between the first frame 10 and the second frame 20. The second frame 20 comprises a pin 92 for engaging the channel or slot 90. In this embodiment, the second frame 20 comprises a flange 95 for mounting the pin 90, preferably located on the first frame member 22. The arrangement of the pin 92 and the channel or slot 90 also assists in guiding movement of the lever arm 50 relative to the second frame 20 as it moves the first frame 10 between the elevated and lowered positions.

[0081] The upper end 52 of the lever arm has a wheel 55, which moves along a track in the form of a channel 100 provided in the first frame 10, as best shown in Figures 2, 5 and 12. This arrangement ensures that the lever arm 50 can securely change between the lowered and elevated positions, as well as enabling a smoother adjustment of the acute angle a between those positions.

[0082] Operation of the lifting mechanism 2 will now be described in relation to the sofa bed 1 moving between its seating and sleeping configurations. The sofa bed 1 is initially in the seating configuration corresponding to the lowered position of the first frame 10, as best shown in Figures 1 and 3A. When it is desired to move the sofa bed 1 to its sleeping configuration, corresponding to the elevated position, operation of the lifting mechanism 2 is initiated pulling the third frame 30 out by its end board or plate 33 and sliding it out using its wheels 35 in the outward direction (as best shown by arrows 120 in Figures 3A). This causes the wheel 37 of the third frame 30 to move along the track 27 of the second frame member 23 of the second frame 20 in the same direction (shown by arrow 130) until it engages the flange 63 of the rod 60, as best shown in Figures 3B and 9. Generally, this usually occurs at approximately 80% of the overall length of the track 27. As the wheel 37 continues to move in the outward direction with the movement of the third frame 30, it pushes or moves the rod 60 along the track 27 in the same outward direction. This causes the rod 60 to also move the lower end 53 of the lever arm 50 in the same linear direction, as best shown by arrow 140 in Figure 3C.

[0083] As a consequence, the lever arm 50 pivots about the fulcrum 70, causing the upper end 52 to move in the opposite direction, as shown by the arrow 150 in Figure 3C. This pivoting movement is facilitated by the spring 80, which pulls the lever arm 50 towards the mounting plate 83 and towards the upright position that will place the first frame 10 into the elevated position. The wheel 55 of the lever arm 50 runs along the channel or track 100 of the first frame 10, assisting pivoting movement of the lever arm. The arrangement of the pin 92 and the slot 90 also guides movement of the lever arm 50, so that it moves from its angled position into the upright position, as best shown in Figures 3D and 6. The pivoting or rotation of the lever arm 50 about the fulcrum 70 causes the end 15 of the first frame 10 to be moved or lifted upwards (as shown by arrows 160 in Figure 3A) into the elevated position, as best shown in Figures 2, 5, 8A and 10. As a result, the sofa bed 1 is now in the sleeping configuration, and the first frame 10 can support a bed mattress, where it is substantially horizontal or flat.

[0084] When the sofa bed 1 is to be moved from the sleeping configuration to the seating configuration, the end board or plate 33 is moved or pushed in an inward direction 170 to insert the third frame 30 into the space between the first and second frames 10, 20, as best shown in Figure 8A. This causes the wheel 37 to run along the track 27 of the second frame 20 in the same direction 175 until it engages the flange 62 of the rod 60, as best shown in Figures 8B and 9. Generally, this engagement wouldalso be approximately 80% of the overall length of the track 27 (but in the opposite direction). Continued movement of the wheel 37 along the track 27 will push the rod 60 in the inward direction via the flange 62, causing the lower end 53 of the lever arm 50 to slide in the track 27 in the same direction 180 against the biasing force of the spring 80, as best shown in Figure 8C. As a result, the lever arm 50 pivots about the fulcrum 70, and its upper end 52 moves in the opposite direction 190 so that the lever arm 50 moves out of its upright position. This in turn causes the first frame 10 move out of the elevated position. Movement of the lever arm 50 is then guided by the wheel 55 in the track 100 and the arrangement of the pin 92 and slot 90 until it returns to its angled position and the first frame 10 moves downwardly as shown by arrow 200 into the lowered position, as best shown in Figures 8A and 8D. The sofa bed 1 is now in the seating configuration, where the first frame 10 is has an acute angle a with respect to the second frame 20. In this way, the first frame 10 can support a seat cushion that is in the optimal ergonomic position for sitting on a sofa.

[0085] Referring to Figures 13A to 13C, the movement of the lever arm 50 and the mechanical advantage provided by the lifting mechanism is shown in more detail. In the lowered position shown in Figure 13A, the lever arm 50 is in its angled position. The fulcrum 70 is located at a distance D1 from the upper end 52 of the lever arm 50 and a distance D2 from the lower end 53 of the lever arm. In this embodiment, distance D2 is preferably twice the distance D1 ; i.e. D2 = 2 x D1. Referring to Figure 13B, a force F2 (from the third frame 30 via the rod 60) is applied to the lower end 53 to pivot the lever arm 50 about the fulcrum 70, as indicated by arrow 210. Since D2 = 2 x D1 , the force F1 applied to the upper end 52 is doubled; i.e. F1 = 2 x F2. This means that less force and hence work or effort is required to pivot the lever arm 50 and thus raise the first frame 10 into the elevated position, as show in Figure 13C. Accordingly, the user requires less effort to move the sofa bed 1 from the seating configuration to the sleeping configuration and vice-versa, reducing labour, improving convenience and minimising the risk of injury.

[0086] It will further be appreciated that any of the features in the preferred embodiments of the disclosure can be combined together and are not necessarily applied in isolation from each other. For example, the described embodiment may be modified to have bosses on the rod 60 as the stops and use a separate track to the channel 27 for the third frame 30. Similarly, the channel 100 and wheel 55 of lever arm 50 could be replaced with a pin in slot arrangement. Similar combinations of two or morefeatures from the above described embodiments or preferred forms of the disclosure can be readily made by one skilled in the art.

[0087] By providing the lift mechanism described above], the disclosure confers the advantages of enabling a frame a sofa bed to be easily moved without the necessity of a motorised mechanism from a lowered position corresponding to a seating configuration to an elevated position corresponding to a sleeping configuration, and vice-versa. The lift mechanism is easy to use and requires less effort by the user, reducing labour and the risk of injury. Moreover, the lift mechanism is relatively simple, making it less complex to manufacture and install in a sofa bed and like furniture. The lift mechanism is also more resistant to damage or maintenance as there is no motor involved and minimal moving parts. These advantages are further enhanced by the provision of various features, like the pin and slot arrangement, the drive arm with stops, the biasing mechanism, integration of the drive member and third frame, and the channel in the first frame for guiding movement of the lever arm. In all these respects, the disclosure represents a practical and commercially significant improvement over the prior art.

Claims

Claims1. A sofa bed, comprising: a first frame configured to support a bed mattress or seating cushion of the sofa bed; a second frame pivotably connected to the first frame at one end; a third frame connected to the second frame and configured for translational movement relative to the second frame to change the sofa bed between a seating configuration and a sleeping configuration; and a lifting mechanism comprising: a lever arm movably connectable to the first frame; and a drive arm engageable with the lever arm; wherein the drive arm is movable to actuate the lever arm; and the lever arm moves the first frame between an elevated position corresponding to the sleeping configuration and a lowered position corresponding to the seating configuration.

2. The sofa bed of claim 1 , wherein the second frame comprises a third track and the third frame is mounted for slidable movement along the third track.

3. The sofa bed of claim 1 or 2, wherein the third frame comprises a drive member that engages the drive arm to move the drive arm into engagement with the lever arm.

4. The sofa bed of claim 3, wherein the drive arm comprises at least one stop and the drive member is engageable with the at least one stop.

5. The sofa bed of claim 3, wherein the drive arm comprises a first stop and a second stop, and the drive member is engageable with the first and second stops, the drive member being movable between the first and second stops to move the first frame between the elevated and lowered positions.

6. The sofa bed of claim 5, wherein the first stop is near or at a first end of the drive arm and the second stop is near or at a second end of the drive arm.

7. The sofa bed of claim 5 or 6, wherein the drive member engages the first stop to move the drive arm and actuate the lever arm, moving the first frame into the elevatedposition; and the drive member engages the second stop to move the drive arm and actuate the lever arm, moving the first frame into the lowered position.

8. The sofa bed of any one of the preceding claims, wherein: the first frame comprises a second track and the lever arm is movable along the second track; in the elevated position, the first frame is substantially parallel to the second frame; and in the lowered position, the first frame defines an acute angle with the second frame.

9. The sofa bed of any one of the preceding claims, wherein the drive arm is moveable along a first track to cause the lever arm to pivot or rotate.

10. The sofa bed of claim 9, wherein the first track is formed in the second frame.

11. The sofa bed of claim 10, wherein the drive member is moveable along the first track.

12. The sofa bed of any one of the preceding claims, wherein the lever arm is rotatably connected to the second frame about a fulcrum or pivot point located on the second frame; the second frame comprises a first frame member and a second frame member spaced apart from each other; the fulcrum or pivot point is located on the first frame member of the second frame; and the fulcrum or pivot point is located closer to the first frame than the second frame member of the second frame.

13. The sofa bed of any one of claims 1 to 11, wherein the second frame comprises a first frame member and a second frame member spaced apart from each other; and a biasing mechanism connects the lever arm to the second frame member of the second frame for biasing the lever arm to move the first frame into the elevated position.

14. The sofa bed of any one of the preceding claims, wherein the lever arm comprises a channel or slot and the second frame comprises a pin for engaging the channel or slot for adjusting the distance between the first frame and the second frame and / or the acute angle between the first frame and the second frame.

15. A method for moving a sofa bed between a seating configuration and a sleeping configuration, wherein a first frame of the sofa bed moves between an elevated position corresponding to the sleeping configuration and a lowered position corresponding to the seating configuration, the method comprising: configuring the first frame to support a bed mattress or seating cushion; providing a second frame pivotably connected to the first frame at one end; configuring a third frame for translational movement relative to the second frame to change the sofa bed between the seating configuration and the sleeping configuration; movably connecting a lever arm to the first frame; engaging the lever arm with a drive arm; and moving the drive arm to actuate the lever arm; wherein movement of the lever arm causes the first frame to move between the elevated position and the lowered position.

16. The method of any one of claim 15, comprising mounting the third frame for slidable movement along a third track in the second frame.

17. The method of claim 15 or 16, wherein the third frame comprises a drive member, the method comprising using the drive member to engage the drive arm for moving the drive arm and pivoting or rotating the lever arm.

18. The method of any one of claims 15 to 17, comprising: arranging the second frame to be spaced apart from the first frame, wherein the second frame comprises at least a first frame member and a second frame member; arranging the first frame member and second frame member substantially parallel to each other; and pivotably connecting the lever arm to the drive arm and moving the drive arm along a first track in the second frame member of the second frame to cause the lever arm to pivot or rotate; wherein the first frame in the elevated position is substantially parallel to the first frame member and the first frame in the lowered position defines an acute angle with the first frame member.

19. The method of claim 18, comprising moving the drive member along the first track.

20. The method of any one of claims 15 to 19, wherein the drive arm has a first stop near or at a first end and a second stop near or at a second end, and the method comprises moving the drive member between the first and second stops.

21. The method of claim 20, comprising moving the drive member to engage the first stop to move the drive arm and actuate the lever arm, thereby moving the first frame into the elevated position; and moving the drive member to engage the second stop to move the drive arm and actuate the lever arm, thereby moving the first frame into the lowered position.

22. The method of any one of claims 15 to 21, comprising rotatably connecting the lever arm to the second frame about a fulcrum or pivot point located on the second frame locating the fulcrum or pivot point such that the fulcrum or pivot point is located closer to the first frame than the second frame member of the second frame.

23. The method of any one of claims 15 to 22, comprising biasing the lever arm towards the elevated position.

24. The method of any one of claims 15 to 23, comprising adjusting the distance between the first frame and the second frame and / or an acute angle between the first frame and the second frame.

25. The method of claim 24, comprising providing a channel or slot in the second frame and a pin engageable with the channel slot for performing the adjusting step.

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