Joint mechanism

1. Field of the Invention

The present invention generally relates to joint mechanisms, and more particularly, to a joint mechanism for rotatably connecting members.

2. Discussion of the Related Art

In some devices, components, such as pivot shafts, pins, and joint bearings, are usually provided to rotatably connect two members of the devices. For example, a device includes an actuating portion, a supporting portion, and a joint mechanism for connecting the actuating portion and the supporting portion. A typical joint mechanism includes a base fixed to the supporting portion and a movable member fixed to the actuating portion. The movable member includes a spherical portion. The spherical portion is rotatably received in a hole of the base. Thus, the movable member together with the actuating portion can be rotated relative to the base and the supporting portion.

Due to friction, wear and tear occurs between the spherical portion of the movable member and the base, thus the service life of the joint mechanism is shortened. Generally, in order to reduce friction, lubricant is continuously applied between the spherical portion of the movable member and the base. This constant maintenance the joint mechanism is inconvenient. In addition, the lubricant and the wear and tear may make the movable member unable to keep a desired fixed position relative to the base.

Therefore, a new joint mechanism that is superior in inhibiting wear and tear is desired.

An exemplary joint mechanism includes a pivot shaft, a joint, a rotary arm, and two bearings. The pivot shaft is non-rotatable relative to the joint. The joint is received in the rotary arm. The rotary arm is rotatable relative to the joint. The two bearings are fixed to an inner surface of the rotary arm. Each bearing includes a concave inner surface, and the concave inner surface is engaged with a curved outer surface of the joint.

Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present joint mechanism. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and all the views are schematic.

FIG. 1 is an assembled view of a joint mechanism in accordance with a preferred embodiment of the present invention.

FIG. 2 is an exploded, isometric view of the joint mechanism shown in FIG. 1 .

FIG. 3 is similar to FIG. 2 , but viewed from another aspect.

FIG. 4 is an enlarged, cross-sectional view of the joint mechanism shown in FIG. 1 , taken along line IV-IV thereof.

Reference will now be made to the drawings to describe preferred embodiments of the present joint mechanism in detail.

Referring to FIGS. 1 through 3 , a joint mechanism 100 in accordance with a preferred embodiment is shown. Some devices, such as toys and electric appliances, usually have an actuating portion and a supporting portion rotatably connected to each other. The joint mechanism 100 is provided to rotatably attach the actuating portion to the supporting portion. The joint mechanism 100 includes a pivot shaft 10 , a pivot ball 20 , a rotary arm 30 , a clip ring 40 , two bearings 50 , a sleeve 60 , and a cover 70 .

The pivot shaft 10 is substantially a hollow rod. A peripheral groove 11 and a latching groove 12 are defined in the pivot shaft 10 . The peripheral groove 11 encircles a cylindrical surface of the pivot shaft 10 adjacent to a first end of the pivot shaft 10 . The peripheral groove 11 is configured for engaging with the clip ring 40 . The latching groove 12 is defined in the first end of the pivot shaft 10 and intersects with the peripheral groove 11 . The latching groove 12 extends parallel to a cylindrical axis of the pivot shaft 10 . The other end (not labeled) of the pivot shaft 10 opposite to the peripheral groove 11 is configured for fixing to the supporting portion of the device.

The pivot ball 20 is substantially a hollow spheroid. The pivot ball 20 defines a shaft hole 21 running through a middle portion of the pivot ball 20 . A latching portion 22 is formed on an inner sidewall (not labeled), of the pivot ball 20 , defining the shaft hole 21 , and a limiting block 23 is formed on one end of the pivot ball 20 . The latching portion 22 is configured for engaging in the latching groove 12 of the pivot shaft 10 . In this way, the pivot ball 20 is non-rotatable relative to the pivot shaft 10 . To reduce a weight of the pivot ball 20 , the pivot ball 20 defines a plurality of holes 24 between the inner sidewall and a spherical outer surface 25 of the pivot ball 20 . Alternatively, the holes 24 may be omitted. The outer surface 25 may be any other kinds of curved surfaces.

In alternative embodiments, the pivot ball 20 may include more than one latching portions 22 . In such cases, there may be more than one latching grooves 12 in the pivot shaft 10 accordingly.

The rotary arm 30 includes a first unit 31 and a second unit 32 that cooperatively form the rotary arm 30 . Each of the first and second units 31 , 32 includes a main body 310 and an extending portion 301 . Each main body 310 has a spherical surface 313 and a flat surface 314 opposite to the spherical surface 313 . The main body 310 of the first unit 31 forms a cylindrical receptacle 312 perpendicularly from an inner surface of the main body 310 . The cylindrical receptacle 312 is substantially a cylinder with a threaded hole (not labeled) defined therein. The second unit 32 defines a circular hole 322 therein. A fastening member (not shown) having a threaded portion is inserted into the circular hole 322 of the second unit 32 and engaged in the threaded hole of the cylindrical receptacle 312 , thereby the second unit 32 is tightly connected to the first unit 31 . The main bodies 310 of the units 31 , 32 each includes a bearing holder 315 having a plurality of fixing ribs 3151 extending from an the inner surface thereof, a stopper portion 316 formed in an inner surface thereof and a latching groove 319 defined in an inner surface thereof. The stopper portions 316 are configured to restrict movements of the limiting block 23 of the pivot ball 20 . Therefore, a rotating range of the rotary arm 30 relative to the pivot ball 20 is restricted. When the rotary arm 30 is assembled, a restricting hole 317 is defined in the spherical surface 313 of the rotary arm 30 , and two receiving grooves 318 are defined in opposite sides of the flat surface 314 of the rotary arm 30 . The rotary arm 30 is rotatably attached to the actuating portion of the device that the joint mechanism 100 employed in.

The clip ring 40 is substantially a C-shaped clip. A pin hole 41 is defined in each end of the clip ring 40 so that the clip ring 40 is easily assembled by inserting pins into the pin holes 41 . The clip ring 40 is engaged in the peripheral groove 11 of the pivot shaft 10 after the pivot shaft 10 protrudes through the pivot ball 20 , thereby preventing the pivot shaft 10 from being detached from the rotary arm 20 .

In alternative embodiment, the pivot shaft 10 may be fixed to the pivot ball 20 by welding or adhesive substances. The pivot shaft 10 can also be integrally made with the pivot ball 20 . In such cases, the latching groove 12 of the pivot shaft 10 , the latching portion 22 of the pivot ball 20 and the clip ring 40 can be omitted.

The bearings 50 are made of plastic materials with high-wearing feature. Each of the bearings 50 includes a smooth, concave inner surface 52 . Each concave inner surface 52 is substantially a spherical surface. The concave inner surfaces 52 of the bearings 50 are oriented symmetrically opposite to each other for engaging with the spherical outer surface 25 of the pivot ball 20 . A plurality of concave portions 51 are defined in an outer surface of each of the bearings 50 for engaging with the fixing ribs 3151 of the bearing holder 315 correspondingly. The bearings 50 can be fixed to the first unit 31 and the second unit 32 by inserting the bearings 50 into the bearing holder 315 . Alternatively, the joint mechanism 100 may include one or more than two bearings 50 . In such cases, there may be one or more than two the bearing holders 315 corresponding to an amount of the bearings 50 . Alternatively, the concave inner surface 52 of each bearing 50 is not limited to be a spherical surface, it can be any other kinds of concave curved surfaces, corresponding to the curved outer surface 25 of the pivot ball 20 .

In an alternative embodiment, the bearings 50 may be fixed to the first unit 31 and the second unit 32 correspondingly by welding or adhesive substances. It can be understood that, the bearings 50 can also be made integrally with the first unit 31 and the second unit 32 correspondingly.

The sleeve 60 is substantially a hollow cylinder with two openings at two ends thereof. A through hole 61 is defined through a cylindrical surface of the sleeve 60 , furthermore a slit 63 is defined communicating between the through hole 61 and an opening of the sleeve 60 . An inner surface of the sleeve 60 forms two latching portions 62 on opposite sides of the through hole 61 . The latching portions 62 are configured for engaging in the latching groove 319 of the rotary arm 30 . A radius of the through hole 61 is the same as or a little larger than that of the extending portion 301 so as to allow the extending portion 301 being inserted through the through hole 61 . When an external force is applied to the slit 63 , the rotary arm 30 can be inserted into the through hole 61 and the main bodies 310 of the rotary arm 30 are received in the sleeve 60 .

The cover 70 is substantially a circular sheet. The cover 70 includes a rim 71 around a middle portion of the cover 70 and two latching portions 72 . The two latching portions 72 are disposed symmetrically to each other relative to a cylindrical axis of the cover 70 , and are configured for engaging in the receiving grooves 318 of the rotary arm 30 .

Referring to FIGS. 2 through 4 , in assembly, with the latching groove 12 engaging with the latching portion 22 of the pivot ball 20 , the pivot shaft 10 is partially inserted into the shaft hole 21 of the pivot ball 20 . The clip ring 40 is engaged with the peripheral groove 11 of the pivot shaft 10 . The bearings 50 are fixed to the first unit 31 and the second unit 32 correspondingly. The pivot ball 20 is positioned between the first unit 31 and the second unit 32 . A fastening member having a threaded portion is inserted into the circular hole 322 of the second unit 32 and engaged in the threaded hole of the cylindrical receptacle 312 . Thereby, the first unit 31 is attached to the second unit 32 . The concave inner surfaces 52 of the bearings 50 are engaged with the spherical outer surface 25 of the rotary arm 20 . An external force is applied to the slit 63 of the sleeve 60 , and then the extending portion 301 is inserted into the hole 61 of the sleeve 60 . The latching portions 62 are engaged in the latching groove 319 of the rotary arm 30 . The cover 70 is engaged with the main body 310 of the rotary arm 30 by inserting the latching portions 72 into the receiving grooves 318 of the rotary arm 30 . Then, the joint mechanism 100 is assembled.

To use the joint mechanism 100 , the pivot shaft 10 is fixed relative to the pivot ball 20 , and the pivot ball 20 is rotatable relative to the rotary arm 30 . When an external force is applied to the rotary arm 30 , the rotary arm 30 rotates around the pivot ball 20 . A friction force is generated between the concave inner surfaces 52 of the bearings 50 and the pivot ball 20 . Thus, the rotary arm 30 is able to be retained in any position relative to the pivot ball 20 .

When the pivot shaft 10 is fixed to a supporting portion of the device, and the rotary arm 30 is rotatably attached to an actuating portion of the device. The actuating portion of the device can be rotated relative to the pivot shaft 10 and the pivot ball 20 . The device can maintain any rotated position because of the friction produced by the bearings 50 and the pivot ball 20 .

It can be understood that, the pivot shaft 10 can also be integrally made with the supporting portion of the device, and the rotary arm 30 can also be integrally made with the actuating portion of the device. The joint mechanism 100 is not limited to use for devices described-above, it can also be used for connecting an actuating portion and a supporting portion of other similar devices.

It can be understood that, the range of rotation of the rotary arm 30 relative to the pivot ball 20 is not only determined by a position of the stopper portions 316 of the rotary arm 30 , but also determined by the size of the restricting hole 317 of the rotary arm 30 . If the size of the restricting hole 317 is relative large, the rotary arm 30 is able to be rotated in a relatively large range. Otherwise, if the size of the restricting hole 317 is relatively small, the rotary arm 30 is able to be rotated in a relatively small range.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.