Lockable Hinge Joint

Abstract

A hinge joint having two arms rotatable about a common axis is lockable in at least one predetermined position. The apparatus includes a locking ratchet engaging locking detents formed on the peripheral edge of one of the arms. A spring tensions the ratchet towards the locking detents. A release lever, tensioned against an arm side, rotates about the common axis. Said lever includes a cam profile substantially eccentric in relation to its center and rises to a first release face ending at a high point outside said peripheral edge. It then slopes downward forming a blocking sector. The blocking sector is substantially concentric and slightly below said peripheral edge. The cam profile then turns inward forming a second release face finally droping downward to form abutting surface. A stop bar positioned within one of the rotational arms confines rotation of the release lever. The locking ratchet engages the detents according to the relative position of said release lever about the common axis so as to lock the joint arm.

Description

This invention relates to a lockable hinge joint having two arms rotatable about a common axis.

More specifically, this invention relates to a rotatable hinge joint capable of being locked in at least one predetermined position by the engagement of a locking ratchet or blade in locking slots located on the peripheral edge of an arm within the joint. The locking ratchet is urged against the slot or detents by means of a tensioning spring. A release lever, positioned concentrically about the common axis regulates the positioning of the locking blade relative to the slots. The release lever comprises a unique cam profile for removing and blocking the locking ratchet as the lever or the arms or both rotate. This is accomplished at appropriate points in the revolution of one arm relative to the other. Joints of this kind are used, for example, in collapsible baby carriages, in adjustable chain backs, in camp beds, in folding ladders as well as in multi-purpose step ladders.

In conventional lockable joints, it has been necessary not only to release the locking bolt or blade by means of a releasing lever, but also to provide means for temporarily securing the releasing bolt in the removed position. This has led to the rather cumbersome two-lever system in prior apparatus. And, when viewed with the fact that both hands are often times required to hold the arms of these rotatable joints, manual frustration inevitably results. Moreover, the two-lever design is costly and complex.

Accordingly, the present invention overcomes the aforementioned disadvantages by providing a lockable hinge joint having a releasing lever with a unique cam profile disposed on its periphery. A locking ratchet thrusts against the peripheral edge of one arm forming the joint. Locking detents or slots are placed on the peripheral edge. A releasing lever including the cam profile either allows or blocks engagement of said locking ratchet in the detents. The apparatus is such that at appropriate positions the movement of said release lever is independnet of the movement of the joint arms. The independent movement of the release cam in conjunction with its cam profile allows unlocking of the apparatus and advancement to the next predetermined position. In one embodiment, an additional cam profile has been placed on the periphery of the joint arm so as to control the sequence of lockable positions.

The present invention deletes the separate unlocking mechanisms of prior apparatus replacing it with a spring-loaded ratchet. This ratchet or blade either follows the release cam profile or the peripheral edge of the arm during appropriate points in the travel of one arm relative to the other. The profile of the release lever is such that at predetermined angles the locking ratchet engages the locking slots or detents. In other positions said cam becomes a blocking sector mandating a predetermined sequence of positions in opening the arms. This opening sequence locks the arms in the customary A-frame step ladder configuration. Upon release, the cam arrangement permits a straight line extended position with an intermediate angle posture assumed as the last locking station.

A further embodiment of the present invention equips the peripheral edge of the arm with three locking positions and without a cam profile on its periphery. Thus, the spring-loaded ratchet urging against the high point of the release cam secures its position relative to rotation of the arms until the pivoting arm engages the release lever handle as the apparatus is shut.

It is therefore an object according to the present invention to provide a lockable hinge joint requiring a single release mechanism.

It is another object of the present invention to provide rotatable lockable hinge joint having a predetermined sequence of operation.

It is still a further object according to the present invention to provide a rotatable hinge joint simple in design and inexpensive to manufacture.

Other objects and features of the present invention will be come apparent from the following detailed description considered in connection with the accompanying drawings which disclose two embodiments of the present invention. It is understood, however, that the drawings are designed for purposes of illustration only and not as definition of the limits of the present invention for which reference should be made to the appended claims.

In the drawings wherein similar reference characters denote similar elements throughout the several views:

FIG. 1 shows a folded lockable hinge according to the present invention in cross section adapted for use as a ladder hinge;

FIG. 2 shows the hinge of FIG. 1 in its first open position;

FIG. 3 shows the hinge of FIG. 2 wherein the release cam profile engages the spring-loaded locking blade, said blade being removed from one of the locking detents;

FIG. 4 shows the hinge of FIG. 3 in its extended position wherein the releasing cam permits the locking blade to engage a locking detent and where said cam begins to lift said blade;

FIG. 5 shows the hinge of FIG. 4 removing of the locking blade from its slot wherein said lever abuts against a travel stop;

FIG. 6 shows the hinge according to FIG. 5 wherein a cam profile on the periphery of the joint arm permits overriding a portion of the release cam as the rotating arm assumes an intermediate position;

FIG. 7 is another embodiment of the present invention having three lockable positions and showing the hinge rotating between two locking detents, and;

FIG. 8 is a cross section taken along the line XII--XII of FIG. 7.

Referring now to FIG. 1 there is shown one embodiment of the lockable joint according to the present invention. Said joint comprises a first arm 10 and a second arm 12 wherein each of said arms comprises respective cross pieces 10a and 12a. Each cross piece having respective sides 10b and 12b. These pieces are easily formed, for example, by stamping or casting. The lower ends 10c and 12c bend inwards resulting in a substantially closed cross section. The two joint arms pivot about common axial pin 14. The pin support structure of arm 10 is integrally formed by extending the two parallel sides 10b of arm 10 in a concentric disc-shaped array as indicated in FIG. 1. The bearing support structure of arm 12 integrally forms sides 12b of arm 12 in a parallel about pin 14. The width of the pin support of arm 12 is narrow enough to pivot within the array as defined by side members 10b of arm 10. Each of the parallel sides 12b contain correlative detents or locking slots 1 through 4. As shown in FIG. 1 and viewing FIG. 8 support discs 12d strengthen the pin supports so that members 12d lie concentric about pin 14 while having the same detent structure as their associated arm members 12b.

Again referring to FIGS. 1 and 8, side members 10b of arm 10 flare outwardly forming guide 16 for positioning ratchet locking or bolt 18 radially from the periphery of pin support extension of 12b. The flaring comprising guide 16 reaches toward the pivot pin 14 permitting the locking ratchet 18 to engage the various detents 1-4. Support 22 is bent inwardly and perpendicular from the longitudinal axis of arm 10b as shown in FIG. 8. Support 22 contains an aperture 24 slidably supporting guide post 26 which on one end is fastened to locking blade 18. Tensioning spring 28 abuts against one side of stop 22 while on the other tensions blade 18 radially against the periphery of pin support 12b.

Spacer 36 mounts about pin 14 and is concentric therewith. As shown in FIG. 8 spacer 36 abuts against strengthening side pieces 12d. Release lever 138 mounts about spacer 36 so that it freely rotates. Thus, the movement of release lever 138 is independent of the movement of arm 12. Hand grip 40 extends from release lever 138 so that on closing the hinge, grip 40 positions itself between arms 10 and 12 as seen in FIG. 1. Again referring to FIG. 8 spring 154 tensions the release lever 138 against re-enforcing structure 12d and joint arm 12b.

It is apparent from FIG. 1 that release lever 138 includes cam surfaces 184, 142, 150, 145 and 142'. The peripheral edge 125 of the pin support of 12b comprises detent structures 1, 2, 3 and 4. Detents 1, 2 and 3 being cut so as to closely follow the outline of locking blade 18. Each detent or slot is angularly disposed on edge 125 providing lockable positioning of arm 12 when release lever 138 allows locking blade 18 to engage the detents.

As can be seen in FIGS. 2 and 3, detents 1, 2 and 3 provide various operating positions of the lockable hinge. Detent 4 as shown in FIGS. 1 and 2 comprise an inclined slope 4' joining abutment face 4" allowing arm 12 to rotate into a closed position.

In FIG. 1, the hinge is shown in its folded position. As seen, locking blade 18 abuts against detent face 4" and rides on detent floor 4'. In operation a force in the direction of arrow C causes arm 12 to rotate as shown while locking ratchet 18 rides on floor 4'. During travel of arm 12 release lever 138 maintains its position relative to arm 10 owing to the abutment of locking ratchet bolt 18 against release face 142". The continuing rotation of arm 12 places detent 1 under ratchet 18 where tensioning spring 128 urges said ratchet into this detent as shown in FIG. 2. As indicated in FIG. 2, the impinging locking ratchet 18 urges against cam surface 142" causing a torque about pivot pin 14 rotating release lever 138 and its protruding handle 40 against joint arm 10. The locked A-frame step ladder configuration of FIG. 2 is achieved.

Referring again to FIG. 2, displacing release lever handle 40 in direction D as shown, urges control surface 142" of release lever 138 to push radially outward against ratchet 18. This displacement causes ratchet 18 to ride on slope 142" to cam high point 145.

FIG. 3 shows removal of blade 18 from detent 1 thereby freeing arm 12. FIG. 3 indicates blade 18 exerting a force against the descending surface adjacent to high point 145. This force exhibits a torque about pin 14 urging release lever 138 and its integrally formed protruding arm 40 against arm 12. Cam profile 150 having a slightly smaller radius than peripheral edge 125 of the pin support of 12b allows locking bolt 18 to rest against edge 125 as arm 12 rotates in direction E as shown.

Locking ratchet 18 has rounded surfaces 180 denying engagement of the tip of said ratchet in detent structure existing above profile 150. As shown in FIG. 3 arm 12 freely rotates in direction E. Spring 15 causes frictional engagement of release lever 138 maintaining its position relative to rotation of arm 12 while ratchet 18 rides peripheral edge 125.

As shown in FIG. 4 rotation of arm 12 eventually causes the positioning of detent 3 under ratchet 18 and the positioning of the release lever is such that locking ratchet 18 fully engages detent 3. The joint arms are now locked in their fully extended position. In this configuration locking ratchet 18 in addition to engaging detent 3 abuts against cam profile 142' as seen.

Referring now to FIGS. 4 and 5 a force on release handle 40 in the direction F as shown causes rotation of release cam 138 until cam surface 184 engages stop 182. This action releases locking ratchet 18 and joint arm 12 again freely rotates. As seen in FIG. 5 arm 12 can rotate in direction G as shown. This rotation causes a co-relative rotation of release lever 138 wherein blade 18 follows the higher cam profile 131 integrally formed on the periphery of the pin support of 12b thereby overriding release cam point 145. As seen in FIG. 5 rotating arm 12 in the direction G as shown causes ratchet 18 to engage detent 2. Blade 18 engaging detent 2 locks arm 12 in an intermediate elbow position suitable for scaffolding. It is to be noted that the unique application of the aforementioned cam surfaces provides for the overriding of detent 2 when the lockable joint is open from its folded position.

Turning now to FIG. 6 and viewing FIG. 5 it is suggested that a force in a direction indicated by arrow H (of FIG. 5) rotates release lever 138 causing lever surface 142" to exhibit a force outwardly and radially against locking ratchet 18. This displaces said ratchet from engagement with locking detents 2. FIG. 6 shows that rotation of release cam 138 causes abutment of grip handle 40 against the inside surface of arm 12. Rotating arm 12 in the direction I as shown blocks the insertion of blade 18 in detent 1. The hinge closes as cam slope 142' guides locking ratchet 18 adjacent to stop surface 4". The sequence of locking steps beings again as shown in FIG. 1 and above described.

Another embodiment according to the present invention is shown in FIG. 7. As suggested locking detents 2 and 3 are positioned on the periphery of pin support of 12b. The operation of the invention shown in FIG. 7 proceeds as described above through FIG. 4. A clockwise rotation of handle 40 causes abutment of release cam profile 184 against stop 182. Arm 12 freely swings in the direction K as shown so that pin support 12b bears ratchet 18 on peripheral edge 125. Rotating arm 12 in direction K as shown causes the inside face to contact handle 40. This urges co-relative rotation of the arm and lever. Ratchet 18 slides down release profile 142" entering detent 4 as shown, closing the apparatus.

While only a few embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.

Claims

What is claimed is:

1. A joint having two arms pivotable about a common axis and lockable with respect to each other in at least one predetermined angular position comprising:

locking means mounted within a first arm for radial movement with respect to the common axis;

a peripheral edge on the second arm extending concentrically about the common axis and having at least one locking detent formed thereon;

biasing means for urging said locking means towards said peripheral edge;

a release lever pivotable about the common axis relative to the arms and having a cam profile including an eccentric portion in relation to its center and rising to a first release face to a high point outside said peripheral edge, a blocking sector portion following the high point and substantially concentric and slightly below said peripheral edge, a second release face following the blocking sector portion, and an abutting surface for confining the rotation of said release lever; and

stop means positioned in the second arm for limiting the movement of said release lever relative to the second arm so that the travel of said release lever ends when the abutting surface strikes said stop means preventing the cam high point from engaging said locking means when an unlocking action is performed by said second release face.

2. The joint as recited in claim 1, further comprising at least three locking detents in the second arm, and a radial projection on said peripheral edge positioned between the second and third detents so that as said release lever abuts against said stop means so that said projection overrides the cam high point.

3. The joint as recited in claim 1, wherein said locking means comprises:

A guide integrally formed within the first arm and directed radially towards said peripheral edge, and

a ratchet moveable in said guide and having rounded edges capable of engaging the locking detents.

4. The joint as described in claim 1, additionally comprising means for frictionally coupling said release lever to the second arm so that at predetermined intervals said release lever rotation is independent of the rotation of the second arm.

5. The joint as recited in claim 4, wherein means for frictionally coupling comprises a rotatable bushing disposed about the common axis, and spring means for biasing said release lever against the inside of the second arm.

6. The joint as recited in claim 1, further comprising re-enforcing members fixed adjacent to the second arm and having locking detents in accurate registration with the detents of the arm.

7. The joint as recited in claim 3, wherein said biasing means comprises a tension spring urging said ratchet towards said peripheral edge.