AU2008237546B2 - Anti-tilt mechanism for a cabinet - Google Patents

Abstract

Abstract An anti-tilt mechanism for a cabinet An anti-tilt mechanism (10) for a cabinet (12). The cabinet (12) including a frame (13) s with a base (14), a top (16) and a plurality of slidable drawers (18) each having a rearwardly mounted bracket (20). The anti-tilt mechanism (10) includes a bar (30) extending between the base (14) and the top (16), a first lever (40) and a tension spring (50). The bar (30) is engageable with the bracket (20) and is adapted to pivot about a longitudinal axis between a first position, allowing one of the drawers (18) to be 10 withdrawn, and a second position preventing any remaining drawer (18) from being withdrawn. The bar (30) pivots responsive to withdrawal or insertion of one of said drawers (18) respectively. The first lever (40) is pivotally connected to the frame (13) and has a first cam surface (42) adapted to drive the bar (30) to the first position, and a second cam surface (44) adapted to drive the bar (30) to the second position. The tension 15 spring (50) extends between the cabinet (12) and the first lever (40), and is adapted to bias the first lever (40) toward the bar (30). The first cam surface (42) abuts the bar (30) drives the bar (30) into the first position, and the second cam surface (44) abuts the bar (30) to drive the bar (30) into the second position. -t 'a LU z < De 00 'U o ,- --

Description

S&F Ref: 882892 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address Advance Metal Products (Aust) Pty Limited, of Applicant: 24 Williamson Street, Ingleburn, New South Wales, 2565, Australia Actual Inventor(s): Humberto Mesa Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: Anti-tilt mechanism for a cabinet Associated Provisional Application Details: [33] Country: [31] Appl'n No(s): [32] Application Date: AU 2007906223 13 Nov 2007 The following statement is a full description of this invention, including the best method of performing it known to me/us: 5845c(1 823340_1) I Anti-tilt mechanism for a cabinet Field of the invention The present invention relates to an anti-tilt mechanism for a cabinet. In 5 particular, the present invention relates to a mechanism for preventing a cabinet drawer from being opened when another drawer is already open. Background of the invention When a cabinet such as a filing cabinet or industrial drawer cabinet is heavily io loaded there is a significant risk that the cabinet will fall over if a number of the drawers are opened simultaneously. This is because the centre of gravity of the cabinet may be significantly shifted away from the footprint of the cabinet frame, depending on the weight of the loaded drawers. Toppling of a cabinet can be particularly dangerous to people located nearby and is it may also result in damage to the cabinet or the goods stored within the cabinet. Anti-tilt cabinets are available which attempt to prevent the cabinet from falling over. Such anti-tilt mechanisms generally attempt to prevent more than one drawer from being opened at a time. Accordingly, when a drawer is opened, the cabinet locks the remaining drawers, such that the majority of the weight supported by the cabinet remains 20 over the footprint of the cabinet frame. A disadvantage of some known anti-tilt mechanisms is that the mechanisms are prone to becoming jammed in an intermediate position. Jamming of the mechanism may result in the anti-tilt function failing, permitting multiple drawers to be withdrawn, or alternatively preventing any of the drawers from being withdrawn despite the cabinet 25 being in an unlocked state. In order to securely contain the goods within the cabinet, anti-tilt cabinets are generally provided with a lock. The lock permits the user to lock all of the drawers when the cabinet is not in use. However, a disadvantage of some existing anti-tilt mechanisms is that whilst the cabinet is in the locked state a person can horizontally insert a flat item 30 such as a ruler between two adjacent drawers and cause the anti-tilt mechanism to disengage the drawers thus overriding the lock. Disadvantageously, this may result in theft from the cabinet, and also permits a user to manually override the anti-tilt mechanism which permits multiple drawers from being simultaneously opened, hence risking toppling of the cabinet. 35 2 Object of the invention It is the object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages, or at least to provide a useful alternative to existing anti-tilt mechanisms. 5 Summary of the invention In a first aspect, the present invention provides an anti-tilt mechanism for a cabinet, the cabinet including a frame with a base and a top and a plurality of slidable drawers each having a rearwardly mounted bracket, the anti-tilt mechanism comprising: 10 a bar extending between said base and said top, said bar being engageable with said bracket and being adapted to pivot about a longitudinal axis between a first position, allowing one of the drawers to be withdrawn, and a second position preventing any remaining drawer from being withdrawn, said bar pivoting responsive to withdrawal or insertion of one of said drawers respectively; is a first lever pivotally connected to said frame, said first lever having a first cam surface adapted to drive said bar to said first position, and a second cam surface adapted to drive said bar to said second position; and a tension spring extending between said cabinet and said first lever, and adapted to bias said first lever toward said bar, 20 wherein said first cam surface abutting said bar drives said bar into said first position, and said second cam surface abutting said bar drives said bar into said second position. A first end of the first lever is preferably pivotally connected to the cabinet and a second end of the first lever is connected to the spring, and the first and second cam 25 surfaces are located between the first and second ends. The first and second cam surfaces are preferably defined by two sides of a generally triangular shaped projection formed on the first lever. The bar preferably includes a bush having a central web and two opposing arms which define an annular channel adapted to receive the first and second cam surfaces. 30 The anti-tilt mechanism preferably further includes a second lever pivotally connected to a trolley, the second lever having a guide surface adapted to assist in guiding the bar during pivoting between the second position and the first position. The anti-tilt mechanism preferably includes a movable trolley having a stopper surface engageable with the bar and adapted to prevent pivoting of the bar in a locked 35 position.

3 The second lever is preferably mounted on the trolley, the trolley being movable between an unlocked position in which the bar is free to pivot, and a locked position in which the stopper surface engages the bar. The trolley is preferably selectively movable by a rack and pinion gear system in a direction which is generally perpendicular to a slide direction of each drawer. A second tension spring preferably extends between the second lever and the trolley, the second tension spring being adapted to bias the second lever toward the bar. Engagement of the stopper surface with the bar preferably prevents the first and second cam surfaces from driving the bar. The first and second levers are preferably located at opposing ends of the bar. In a second aspect, the present invention provides an anti-tilt mechanism for a cabinet, the cabinet including a frame with a base and a top and a plurality of slidable drawers each having a rear engagement bracket, the anti-tilt mechanism comprising: a bar extending between said base and said top, said bar being engageable with said engagement bracket and being adapted to pivot about a longitudinal axis between a first position, allowing one of the drawers to be withdrawn, and a second position preventing any remaining drawer from being withdrawn, said bar pivoting responsive to withdrawal or insertion of one of said drawers respectively; a trolley movable between a locked position and an unlocked position, said trolley having an aperture formed therein and a portion of the bar passes through said aperture, a lever pivotally connected to said trolley, said lever having a guide surface engageable with said bar; wherein in the locked position, an edge of said aperture is engageable with said bar and adapted to prevent pivoting of said bar; further wherein movement of said trolley from the locked position to the unlocked position causes said edge to disengage said bar and said guide surface to guide said bar to said first position.

3a Brief Description of the Drawings Fig. 1 is a bottom view of a drive mechanism of an anti-tilt mechanism of an embodiment of a cabinet; Fig. 2 is a top perspective view of the drive mechanism of Fig. 1; Fig. 3 is a bottom perspective view of the drive mechanism of Fig. 1; 4 Fig. 4 is a top view of a lock and reset mechanism of the anti-tilt mechanism shown in Fig. 1; Fig. 5 is a top perspective view of the lock and reset mechanism of Fig. 4; Fig. 6 is a top view of the lock and reset mechanism of Fig. 4 in a locked 5 position; Fig. 7 is a top view of the lock and reset mechanism of Fig. 4 in an unlocked position; Fig. 8 is a top view of the lock and reset mechanism of Fig. 4 in a reset position; Fig. 9 shows a partial cutaway perspective view of the cabinet of Fig. 1; 10 Fig. 10 shows a partial cutaway perspective view of the cabinet of Fig. 1 with a drawer; and Fig 11 shows a bottom partial cutaway view of the cabinet of Fig. I and a detail of the drawer engagement bracket. 1s5 Detailed description of the preferred embodiment Figs. 9 to 11 show an embodiment of a cabinet 12, and Figs I to 8 show an embodiment of an anti-tilt mechanism 10 which is installed within the cabinet 12. The cabinet 12 has a frame 13 with a base 14, a top 16 and a plurality of slidable drawers 18. The drawers 18 have slide rails 19 mounted on each side, which slide 20 relative to corresponding rails 17 mounted within the frame 13 of the cabinet 12. Each of the drawer rails 19 and the cabinet rails 17 includes rollers 21. Each of the drawers 18 also includes a rearwardly mounted engagement bracket 20, shown in detail in Fig. 11. The anti-tilt mechanism 10 includes a drive mechanism 24 located toward the 25 base 14, as depicted in Figs. I to 3. The anti-tilt mechanism 10 also includes a reset and lock mechanism 22 located toward the top 16 of the cabinet 12 and depicted in Figs. 4 to 8. A bar 30 extends between the base 14 and the top 16, and is connected to both the reset and lock mechanism 22 and the drive mechanism 24. The bar 30 is adapted to 30 pivot about its longitudinal axis XX. As shown in Fig. 3, the bar 30 is mounted to the drive mechanism 24 with a first pin 32 at each end, which are located on the pivot axis XX. The bar 30 also has a second pin 34 at each end, which are located a perpendicular distance from the pivot axis XX. The second pin 34 passes through a slot or cut-out 36 formed in a horizontal plate 38 of the drive mechanism 24. The bar 30 is also mounted in 35 a similar manner to the reset and lock mechanism 22 at the top 16 of the cabinet 12.

5 The bar 30 has a generally S-shaped profile when viewed in a plane extending perpendicular to the pivot axis XX, and the profile of the bar 30 defines a hook 31 which is engageable with the engagement bracket 20 of each drawer 18. The bar 30 is adapted to pivot about the pivot axis XX between a first position, allowing any one of the drawers 5 18 to be withdrawn, and a second position preventing any remaining drawer 20 from being withdrawn. The bar 30 pivots responsive to withdrawal or insertion of any one of the drawers 18 respectively. The drive mechanism 24 includes a first lever 40 which is pivotally connected to the cabinet 12 frame. The first lever 40 has a first cam surface 42 adapted to drive the bar 10 30 to the first position, and a second cam surface 44 adapted to drive the bar to the second position. The first and second cam surfaces 42, 44 are defined by two sides of a generally triangular shaped projection formed on the first lever 40. The triangular projection has a rounded apex 41. The second pin 34 includes a bush 60 having a sheave shaped profile defined by is a central web and two opposing arms which define an annular channel adapted to receive said first and second cam surfaces 42, 44. The radius of the bush 60 is substantially larger than the radius of the apex 41. The drive mechanism 24 also includes a tension spring 50 which extends between the cabinet 12 and the first lever 40. The tension spring 50 may be a coil spring, 20 an elastic band or any other tensionally mounted spring element that is adapted to bias the first lever 40 toward the bar 30. As a result, that when the first cam surface 42 abuts the bar 30, the bar 30 is driven into the first position. Similarly, when the second cam surface 44 abuts the bar 30, the bar 30 is driven into the second position. The tension spring 50 ensures that the drive mechanism 34 continually applies a 25 force to the bar 30, and the bar 30 is prevented from coming to rest at an intermediate position in which the bush 60 is in contact with or adjacent to the apex 41 of the triangle defined by the first and second cam surfaces 42, 44. The movement between the first position and the second position is assisted by the fact that the radius of the bush 60 is considerably greater than the radius formed on the apex 41. 30 The bush 60 is retained on the end of the bar 30 and rolls along the edge of the first lever 40 as the bar 30 is driven between the first and second positions and vice versa. The movement between the first and second positions is assisted by the fact the rolling friction on the bush 60 is substantially less than the sliding friction that would otherwise be present in the absence of the bush 60.

6 A first end 52 of the first lever 40 is pivotally connected to the cabinet 12, and a second end 54 of the first lever 40 is connected to the tension spring 50. The first and second cam surfaces 42, 44 are located between the first and second ends 52, 54. The reset and lock mechanism 22 is located at an opposing end of the bar 30, 5 toward to the top of the cabinet 12, and engages the bar 30 in a similar manner as described above. Fig. 4 shows the reset and lock mechanism 22. The reset and lock mechanism 22 includes an arc shaped slot or cut-out 71 which is fixed relative to the cabinet frame 13. The arc shaped cut-out 71 corresponds to the range of pivotal motion of the bar 30. 1o Accordingly, the second pin 34 passes through the arc shaped cut-out 71 and is permitted to travel within the arc shaped cut-out 71. The reset and lock mechanism 22 includes a second lever 70 as shown in Fig. 4. The second lever 70 is mounted on a trolley 76, and the trolley 76 is movable in a direction which is generally perpendicular to a slide direction of the drawers 18. The is movement corresponds to movement between the left and right in Figs. 6 to 8. The second lever 70 is mounted on the trolley 76 and accordingly the second lever 70 moves with the trolley 76 during its range of motion. The second lever 70 is pivotally mounted to the trolley 76 at a first end and 73 and mounted to a tension spring 78 at a second end. The second lever 70 includes a first guide 20 surface 72 and a second guide surface 74 which are defined by two sides of a triangular projection formed on the second lever 70. The trolley 76 has an aperture in the form of a generally rectangular cut-out 77 formed therein. The rectangular cut-out 77 is superposed above the arc shaped cut-out 71. However, the rectangular cut-out 77 moves with the trolley 76, while the arc shaped cut-out 71 remains fixed relative to the frame 13. 25 The reset and lock mechanism 22 includes a rack and pinion gear train 90. A pinion gear 92 shown in Fig. 5 is connected to a rod 94 which extends parallel to a slide direction of the drawers 18. The rod 94 is connected to a lock 95, which is located on a front face of the cabinet 12. By turning a key in the lock 95, a user causes the rod 94 to rotate and hence the pinion gear 92 rotates with the rod 94. The meshing between the 30 pinion gear 92 and the rack 96 results in movement of the trolley 76 in a direction which is perpendicular to the slide direction of each drawer 18. The second pin 34 passes through both the arc shaped cut-out 71 and the rectangular cut-out 77. In the locked position shown in Fig. 6, the pin is trapped between an edge 79 of the rectangular cut-out 77 and the end of the arc shaped cut-out 71. 35 Accordingly, in this position, the reset and lock mechanism 22 overrides the drive 7 mechanism 24, thereby preventing the bar 30 from pivoting about the axis XX. Accordingly, the cabinet is locked and none of the drawers 18 can be withdrawn. The use of the anti-tilt mechanism 10 of the cabinet 12 will now be described. When a user intends to open one of the drawers 18, the key is turned to the unlocked 5 position which results in the trolley 76 moving to the unlocked, first position shown in Fig. 7. In this first position, the drawers 20 are all fully positioned within the cabinet 12, and the bar 30 is free to pivot about the pivot axis XX. When a user pulls one of the drawers 20 away from the cabinet 12, the engagement of the rear engagement bracket 20 with the bar 30, causes the bar 30 to move between the first position, as depicted in Fig. 7, 1o toward the second position as shown in Figs. I to 3. Turning of the key results in the trolley 76 moveing toward the right from the position shown in Fig. 6 toward the position shown in Fig. 7. During this movement, the second guide surface 74 engages the pin 34, and guides the pin to move within the arc shaped cut-out 71. When the reset and lock mechanism 22 arrives at the unlocked position is as shown in Fig. 7, the rectangular cut-out 77 is located generally above the arc shaped cut-out 71. Accordingly, the pin 34 is free to move within the arc shaped cut-out 71 responsive to pivoting of the bar 30 by the drive mechanism 24. In this first position, the bar 30 is not in contact with the second lever 70 or the rectangular cut-out 77, and pivoting of the bar is controlled by the drive mechanism 24. 20 During the use of the cabinet 12, a user generated fault may occur. For example, the cabinet 12 may be effectively unlocked, but none of the drawers 18 are able to be withdrawn, on account of the bar 30 being in the in correct pivotal position. It is accordingly necessary to then reset the reset and lock mechanism 22. The resetting operation involves the user turning the key, which has the effect of 25 causing the trolley 76 to move to the left toward the position shown in Fig. 8. As this movement occurs, the first guide surface 72 contacts the pin 34 and this engagement causes the second lever to pivot about its first end 73. The tension spring 78 simultaneously extends to permit the pivotal motion of the second lever 70, and as shown in Fig. 8 an apex 81 defined by the first and second guide surfaces 72, 74 eventually 30 contacts the pin 34, and the spring 78 is at its point of maximum extension. Further movement of the trolley 76 toward the left results in the pin 34 passing the apex 81, and the spring 78 retracts, pulling the second lever back to the locked position shown in Fig. 6.

8 At this point the cabinet 12 is correctly locked and the fault has been reset. If a user wishes to then open a drawer of the cabinet 12, the key is turned again and the trolley 76 moves back to the unlocked position of Fig. 7, as described above. Any one of the drawers 18 may now be opened as desired. 5 In the unlocked state of operation, as the drawer 18 is pulled by a user, the bar 30 moves between the first position and the second position. The first cam surface 42 slides along the bush 60. As the bush 60 approaches the apex 41, the tensional force in the spring 50 is at its greatest. This assists to continue the pivoting of the bar 30 until it reaches the second position. 10 Once the bush 60 has passed the apex 41, the spring retracts and the bar 30 comes to rest in the second position. When the bar has reaches the second position, the rear engagement bracket 20 of the drawer 18 is disengaged from the bar 30. At this point, the drawer 18 is able to be fully withdrawn as desired. However, in this second position, the bar 30 is now engaged with all of the brackets 20 of the is remaining drawers 18. Accordingly, the user is unable to retract another drawer 18 from the cabinet 12. When a user intends to open a different drawer 18, the first drawer 18 must be returned to the original starting, first position (as depicted in Figs. 7). As the drawer 18 is inserted into the cabinet 12, near the end of its stroke, the rear engagement formation 20 20 again comes into abutment with the bar 30. The abutment forces the bar 30 to commence pivoting in the opposite direction and return toward the first position, such that the second cam surface 44 slides along the bush 60, and the bush 60 passes the apex 41 and then slides along the first cam surface 42. During each transition between the second and first positions, the bush 60 passes 25 the apex of the triangle defined by the first and second cam surfaces 42, 44 and the spring 50 applies a biasing force to push the bar 30 completely to the end of its pivot stroke toward the first or second position as required. When the anti-tilt mechanism 10 has returned to the first position, any one of the drawers 18 is free to be withdrawn from the cabinet 12, or the cabinet 12 may be locked 30 by turning the key, and returning the trolley 76 to the locked position. In the event that the mechanism is incorrectly loaded such that more than one drawer is withdrawn at the same time, the lock and reset mechanism 22 may be operated as described above by the key to manually return the anti-tilt mechanism back to the normal, anti-tilt first position.

9 Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims (12)

1. An anti-tilt mechanism for a cabinet, the cabinet including a frame with a base and a top and a plurality of slidable drawers each having a rearwardly mounted bracket, the anti-tilt mechanism comprising: a bar extending between said base and said top, said bar being engageable with said bracket and being adapted to pivot about a longitudinal axis between a first position, allowing one of the drawers to be withdrawn, and a second position preventing any remaining drawer from being withdrawn, said bar pivoting responsive to withdrawal or insertion of one of said drawers respectively; a first lever pivotally connected to said frame, said first lever having a first cam surface adapted to drive said bar to said first position, and a second cam surface adapted to drive said bar to said second position; and a tension spring extending between said cabinet and said first lever, and adapted to bias said first lever toward said bar, wherein said first cam surface abutting said bar drives said bar into said first position, and said second cam surface abutting said bar drives said bar into said second position.

2. The anti-tilt mechanism as claimed in claim 1, wherein a first end of the first lever is pivotally connected to the cabinet and a second end of the first lever is connected to the spring, and the first and second cam surfaces are located between the first and second ends.

3. The anti-tilt mechanism as claimed in claim 1 or 2, wherein the first and second cam surfaces are defined by two sides of a generally triangular shaped projection formed on the first lever.

4. The anti-tilt mechanism as claimed in claim 1, 2 or 3, wherein the bar includes a bush having a central web and two opposing arms which define an annular channel adapted to receive the first and second cam surfaces.

5. The anti-tilt mechanism as claimed in any one of claims 1 to 4, further including a second lever pivotally connected to a movable trolley, the second lever having a guide surface adapted to assist in guiding the bar during pivoting between the second position and the first position. l1

6. The anti-tilt mechanism as claimed in any one of claim 5, wherein the movable trolley includes a stopper surface engageable with the bar and adapted to prevent pivoting of the bar in a locked position.

7. The anti-tilt mechanism as claimed in claim 6, wherein the second lever is mounted on the trolley, the trolley being movable between an unlocked position in which the bar is free to pivot, and a locked position in which the stopper surface engages the bar.

8. The anti-tilt mechanism as claimed in claim 7, wherein the trolley is selectively movable by a rack and pinion gear system in a direction which is generally perpendicular to a slide direction of each drawer.

9. The anti-tilt mechanism as claimed in claim 8, wherein a second tension spring extends between the second lever and the trolley, the second tension spring being adapted to bias the second lever toward the bar.

10. The anti-tilt mechanism as claimed in claim 9, wherein engagement of the stopper surface with the bar prevents the first and second cam surfaces from driving the bar.

11. The anti-tilt mechanism as claimed in any one of claims 5 to 10, wherein the first and second levers are preferably located at opposing ends of the bar.

12. An anti-tilt mechanism for a cabinet, the cabinet including a frame with a base and a top and a plurality of slidable drawers each having a rear engagement bracket, the anti-tilt mechanism comprising: a bar extending between said base and said top, said bar being engageable with said engagement bracket and being adapted to pivot about a longitudinal axis between a first position, allowing one of the drawers to be withdrawn, and a second position preventing any remaining drawer from being withdrawn, said bar pivoting responsive to withdrawal or insertion of one of said drawers respectively; a trolley movable between a locked position and an unlocked position, said trolley having an aperture formed therein and a portion of the bar passes through said aperture, a lever pivotally connected to said trolley, said lever having a guide surface engageable with said bar; 12 wherein in the locked position, an edge of said aperture is engageable with said bar and adapted to prevent pivoting of said bar; further wherein movement of said trolley from the locked position to the unlocked position causes said edge to disengage said bar and said guide surface to guide said bar to said first position. Gilkon Pty Limited Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON