GB2275606A

GB2275606A - A folding stool

Info

Publication number: GB2275606A
Application number: GB9401569A
Authority: GB
Inventors: David P Oliver; Stephen Bassett
Original assignee: Abru Aluminium Ltd
Current assignee: Abru Aluminium Ltd
Priority date: 1993-01-27
Filing date: 1994-01-27
Publication date: 1994-09-07
Anticipated expiration: 2014-01-27
Also published as: GB9401569D0; GB2275606B

Abstract

A folding stool has a seat (11), two pairs of legs (12; 14) pivoted to the seat (11) and interconnected by struts (17) pivotally attached to corresponding legs (12, 14) of each pair, and a locking link (25) pivotally mounted to an intermediate point (20) on the strut (17) and having an elongate slot (26) with an elbow portion (28) which, in the locking position of the locking link (25) is engaged over a pin (27). The pin has a circumferential groove (34) which traps the slot (26), and the shape of the locking link (25) is such that the triangular space defined by the leg (12) and the strut (17) from the pivotal connection (22) to the pin (27) and the pivotal mount of the locking link (25) on the strut (17), is substantially occluded when the locking link (25) is in its locked position. Steps (15) are also provided. <IMAGE>

Description

A FOLDING STOOL The present invention relates to a folding stool and particularly to a folding stool having an improved locking device.

Folding stools are known which have a seat and two pairs of legs, front and back, pivoted to the seat and interconnected by hinged struts. The pivotal connections allow the stool to take up an erect condition in which the front and back legs are splayed apart to support the seat in a horizontal position of use. When folded the legs, seat and struts are pivoted into a compact condition in which they lie alongside each other for storage.

Such stools may be provided with locking catches which act between the strut and a leg and serve as safety devices for locking the struts in the stool-erected position. A known such locking and operating device comprises an elongate link attached at one end to a pin at an intermediate position along the strut and extending towards the associated rear leg where an elongate slot of the link slidably engages a locking pin on the leg. The link and the rear part of the strut form a triangle with the associated part of the rear leg in the erected condition of the stool. In use, the locking link can be lifted upwardly to release the locking pin from an elbow of the slot and allow it to slide along the main limb of the slot permitting the strut and rear leg to fold together as the stool is collapsed.The stool is erected from the folded condition by a manoeuvre in the opposite direction with the locking pin finally being engaged in the elbow of the slot to lock the locking link in position.

A disadvantage encountered in use of such folding stools is that the operator is tempted to grasp the locking link at a mid position which means that his fingers may extend between the link and the strut and may be trapped and pinched as these are folded together. Although it is known to extend the link beyond the rear leg of such a stool to provide an operating finger, this does not altogether obviate the problem as it is still possible to introduce the operator's fingers between the lock and the link itself.

The object of the present invention is to devise a locking and operating device for a folding stool of the type described above which does not constitute a hazard to the operator in the above manner.

Accordingly, the present invention provides a folding stool having a seat, two pairs of legs pivoted to the seat and interconnected by at least one strut pivotally attached to corresponding legs of each pair and a locking link pivotally mounted to an intermediate point on the strut and having an elongate slot engaged over a pin projecting from one leg, the slot having an elbow portion in which the pin is located in the locking position of the locking link, in which the locking link is shaped such that in the said locking position it substantially occludes the triangular space defined by the pin, the pivotal coupling of the locking link to the said strut, and the pivotal connection of the strut to the leg from which the said pin projects, the said locking link having an operating appendage for engagement to turn it about its pivotal coupling to the strut whereby to release or engage the pin in the locking elbow of the slot.

The operating appendage may comprise a finger or hand grip projecting laterally from the face of the locking link, and may be formed integrally with or attached to the link. In the case of a metal structure, the appendage is preferably formed by bending a tab of the sheet metal out of the plane of the main body of the link. Such a tab is preferably formed at an edge of the link, preferably but not exclusively the upper edge in use, but could be formed by partial blanking from the centre of the plate.The aperture formed by such partial blanking would preferably be above the tab itself and not large enough for the insertion of the fingers so that this does not provide the same degree of hazard as a gap between the link and the stool leg and strut One embodiment of the invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a folding step stool in its erect condition; Figure 2 is an enlarged side elevational view of a locking link forming part of the stool of Figure 1; and Figure 3 is an enlarged sectional view of the link and the strut of Figure 1 taken on the line III-III of Figure 2.

With reference to the drawings, a folding step stool is generally indicated 10. The stool 10 comprises a seat 11, two rear legs 12 interconnected by a rail 13 and two front legs 14 interconnected by two steps 15. Each leg 12, 14 is pivotally connected by a pin 16 to a channel member 36 attached to the seat 11, for pivoting in known manner, about an axis perpendicular to a plane of symmetry from the front to the back of the stool. The stool can thus take up an erect condition, shown in Figure 1, in which the front and back legs are splayed apart so as to support the seat 11 stably in a horizontal position or it can take up a folded condition, not shown, in which the seat lies in substantially the same plane as the rear legs and the front legs lie against the seat and the rear legs.

In order to prevent the front and back legs from splaying apart beyond their proper positions in the erect condition of the stool 10, each pair of front and rear legs is interconnected by a pivoted strut 17. Each strut 17 is connected at its respective ends by pivot pins 21, 22 to the associated front and rear legs 14, 12 respectively, the pivot axes being parallel to the axes of the leg pivot pins 16. The front pivot pin 21 is closer to the seat 11 than the rear pin 22 such that, in the erect condition of the stool, the struts 17 are inclined upwardly and forwardly from the rear pin 22 to the front pin 21. As can be seen in Figure 1, a spacer 37 at each end of each strut 17 holds the strut itself spaced about 15mm from the adjacent leg.When the stool 10 is folded, the struts 17 form, together with the seat 11 and the parts of the front and rear leg 12, 14 between strut and seat, a quadrilateral linkage allowing the stool to fold to a position in which the strut 17 lies generally parallel to the leg 12.

In order to lock the struts 17 in the position adopted when the stool is erected a locking link generally indicated 24 is provided for each strut 17. This link 24 comprises a generally triangular catch plate 25 pivoted adjacent one corner on a central pin 20 of a respective strut 17 and extending from there towards the associated rear leg 12 in a plane adjacent and parallel to the outer side faces of the front and rear legs 14, 12 of the respective pair.

The catch plate 25 engages the rear leg 12 by means of an elongate through-slot 26 slidable on a locking pin 27, best seen in Figure 3, projecting from the outer side face of the leg 12. More specifically, the projecting portion of the locking pin 27 is generally cylindrical with a circumferential bevel 31 joining its free end face 32 to its cylindrical surface 33 and a circumferential groove 34 in the cylindrical surface 33 close to the free end 32. The groove 34 is of such a depth and width, the catch plate 25 is of such a thickness and its slot 26 is of such a width that the opposing longitudinal edges of the slot seat in the groove 34 with only slight clearance. The catch plate 25 can thus slide on the pin 27, the pin 27 moving along the slot 26, but is restrained from relative lateral movement by cooperating engagement of the slot edges with the groove 34. The interconnection of the catch plate 25 and the pin 27 by means of the annular groove 34 is of some significance since it provides lateral restraint in both directions allowing the plate 25 to be spaced further from the leg than would be the case if the pin merely has a mushroom head as has been used in previous such linkages. The catch plate 25, which is pivoted to the link 17, itself held by spacers 37 laterally away from the legs 12, 14, can thus function securely notwithstanding this spacing, without lateral slackness introducing any functional irregularities.

The slot 26 has a rectilinear major portion which terminates at each end in respective elbow portion 28, 29, extending in generally opposite directions laterally of the slot 26 with the portion 29 terminating in a circular, enlarged end portion 29a the function of which will be described below. The slot 26 is so arranged that the locking pin 27 can be engaged in the elbow portion 28, which is close to a corner of the plate 25, when the stool is erected. In this position, as shown in Figure 3, an approximately semicircular end edge of the plate 26, defining a rounded end of the slot portion 29, engages the groove 34 and this engagement locks the quadrilateral linkage comprising the strut 17, the seat 11 and the upper parts of the front and rear legs 12, 14 in the erected position. The pin 27 slides along the rectilinear portion when the stool is folded.The enlarged end portion 29a allows the free end of the pin 27 to pass through upon assembly, the bevel 31 facilitating the insertion, but otherwise playing no part in the normal operation of the stool except to present a safely rounded aspect to the outside.

When the stool is erected, the triangular catch plate 25 effectively covers the triangular opening between the rear leg 12 and the rear part of the strut 17, the corners of this opening being defined essentially by the rear strut pin 22, the central strut pin 20 and the locking pin 27. A user of the stool 11 cannot therefore grasp the plate 25 and trap his fingers between the strut 17 and the leg 12 when the wishes to fold the stool 11.

Instead, in order to operate the locking plate 25, a projecting finger grip 30 is provided; in this embodiment the finger grip 30 is constituted by a portion of the sheet metal from which the plate 25 is cut and which projects from the upper edge (as seen in the drawings) of the plate 25, being bent outwardly of the plane of the plate 25.

In order to fold the stool 11, the finger grip 30 is engaged and pulled upwards to release the locking pin 27 from the slot elbow 28 so that the strut 17 and the leg 12 can fold together. With this movement the pin 27 slides along the slot 26 towards (without reaching) the other elbow 29 at the opposite end of the slot when the stool is fully collapsed.

In an alternative embodiment (not shown) the finger grip 30 is formed by bending out from the triangular catch plate a tab punched from the body of the triangular catch plate 25. As a further alternative the finger grip 30 may be formed at the lower rather than the upper edge of the triangular catch plate 25.

Claims

1. A folding stool having a seat, two pairs of legs pivoted to the seat and interconnected by at least one strut pivotally attached to corresponding legs of each pair and a locking link pivotally mounted to an intermediate point on the strut and having an elongate slot engaged over a pin projecting from one leg, the slot having an elbow portion in which the pin is located in the locking position of the locking link, in which the locking link is shaped such that in the said locking position it substantially occludes the triangular space defined by the pin, the pivotal coupling of the locking link to the said strut, and the pivotal connection of the strut to the leg from which the said pin projects, the said locking link having an operating appendage for engagement to turn it about its pivotal coupling to the strut whereby to release or engage the pin in the locking elbow of the slot.

2. A folding stool as claimed in Claim 1, in which the said operating appendage projects from the general plane of the locking link.

3. A folding stool as claimed in Claim 1 or Claim 2, in which the said operating appendage is formed as a finger or hand grip.

4. A folding stool as claimed in any of Claims 1 to 3, in which the said operating appendage is integrally formed with the said locking link.

5. A folding stool as claimed in any preceding Claim, in which the operating appendage is bent from the material of the link.

6. A folding stool as claimed in Claim 5, in which the said operating appendage is bent from one edge of the locking link in the form of a tab.

7. A folding stool as claimed in Claim 5, in which the operating appendage is bent from a central portion of the locking link.

8. A folding stool as claimed in any of Claims 1 to 3, in which the operating appendage is attached to the locking link by fixing means.

9. A folding stool as claimed in any preceding Claim1 in which the said slot in the locking link has an elbow portion at each end whereby to define secured end positions.

10. A folding stool as claimed in any preceding Claim, in which the pin projecting from the leg has a circumferential groove engaged by the edges of the locking link defining the slot therein, and in which the slot has an enlarged portion remote from the said elbow whereby to allow introduction of the pin into engagement with the slot.

11. A folding stool as claimed in Claim 10, in which the said circumferential groove is positioned axially such as to be in alignment with the locking link, with the said strut between the locking link and the leg.

12. A folding stool substantially as hereinbefore described 'with reference to, and as shown in, the accompanying drawings.