GB2519323A

GB2519323A - A self-contained spring to mass support arm

Info

Publication number: GB2519323A
Application number: GB1318337.1A
Authority: GB
Inventors: Christopher Harper-Mears
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-10-16
Filing date: 2013-10-16
Publication date: 2015-04-22
Anticipated expiration: 2033-10-16
Also published as: GB2519323B; GB201318337D0

Abstract

A self-contained spring-to-mass support arm is provided. The support arm comprises a supported mass 1 attached to a pivoted forearm 2, which is arranged to rotate about the centre point of an outer gear ring 3.The outer gear ring 3 is rigidly attached to an upper arm 6 which, in turn, is rigidly fixed to a shoulder 7. The pivoted forearm 2 is pivoted off the upper arm 6. An inner orbital gear 4 is affixed to the forearm 2 so that, when the forearm 2 rotates about its pivot point, the orbital gear 4, which is engaged with the outer gear ring 3, will rotate. The countenance spring 5, which can be of a standard or zero free length type depending on whether the mass 1 is required to be supported at one or more end rest positions of the forearm 2, is affixed to the inner orbital gear 4 and back to the upper arm 6.

Description

Title of Invention:

Self-Contained Spring-to-Mass Support Arm

Description

Background-

Most, if not all, purely spring-to-mass support-arms, to-date, are simply geometric embodiments of the arrangements shown in Figure land Figure 2. These mechanical arrangements, or variants thereof, are generally used as orthopaedic support devices to offer full or partial support of the body. These passive exoskeletons can, for example, assist the wearer with leg or arm rehabilitation, in cases of degenerative muscle wasting decease, during manual handling tasks or to reduce repetitive-action fatigue.

Referring to Figure 1: This is the simplest of arrangements whereby we have a pivoted arm with a mass supported at the distal end of that arm. The weight of that mass is countered by the external spring shown.

Problem: The use of externally located spring: a) Increases the bulk of the support arm, especially outside of the immediate elbow joint.

b) Increases the risk of entrapment as the spring contracts.

Referring to Figure 2: The second existing type of spring to mass support arm uses parallelograms or pantograph arrangements within the support arm structure.

Problem: The use of parallelograms or pantographs: a) Limits the range of movement of the support arm as the braces & springs cannot cross-over themselves as they are not revolute in this set up.

b) Increases the bulk of the support arm, thus making it more visually intrusive and the wearer self-conscious..

c) Increases the risk of pinching the wearer.

A generic example of existing arm supports can be seen in Figure 9 (Note the bulk of the parallelogram and elbow joint).

To overcome the above shortcomings in existing patented designs, this invention (see Figure 3) uniquely: a) Encloses & maintains the countenance spring, whether that spring exhibits zero free length properties or not, within the support arm brace at all times.

b) Removes the requirement to use parallelograms or pantograph geometry.

c) Significantly reduces the bulk of the support arm.

d) Directs the spring countenance force through a straight line mechanism located within the elbow compartment.

Looking at FIGURE 4, we have a supported mass (1) attached to a pivoted forearm (2), which can be said to rotate about the equivalent centre point of the outer gear ring (3).

The outer gear ring (3) is rigidly attached to the upper arm (6) which, in turn, is rigidly fixed to the shoulder (7). The pivoted forearm is pivoted off the upper arm (6).

The inner orbital gear (4) is affixed to the forearm (2)so that, when the forearm rotates about its pivot point, the orbital gear, which is engaged with the outer gear ring (3), will rotate.

The countenance spring (6), which can be of a standard or zero free length type-depending on whether the mass is required to be supported at one or more end rest positions of the support forearm, is affixed to the inner orbital gear (4) back to the upper arm (6).

This arrangement of the gears is historically classified as a straight line mechanism, meaning that upon rotation of the inner gear about the outer gear, a point on that inner gear will track a straight line.

Therefore, if we refer to figure 5, we can show that in this unique arrangement, the countenance spring, upon contraction, as the forearm elevates its supported mass, remains centralised within the upper arm brace. The spring force, it can be shown here, acts in opposition to the downwards pull of the supported mass at all times, even through 180 degrees of rotation of the support arm.

An embodiment of this invention, which offers further degrees of freedom of the spring to mass support arm, can be seen in Figure 6, with examples of that range of movement shown in Figure 7.

A further embodiment of this invention -Figure 8-shows the countenance spring located within the forearm. This is achieved by rigidly affixing the inner gear to the upper arm, and allowing the outer ring gear to rotate with the forearm. As per figure 6, this embodiment is also modular.

Claims

Claims 1. A self-contained spring to mass support arm, with the support arm comprising: a balance arm, an elbow containing a straight line mechanism, and a spring contained within either the balance arm or preceding support and so arranged that the spring remains centralised within its housing at all times during the displacement of the balance arm and subsequent contraction and extension of the spring.
2. A self-contained spring to mass support arm according to claim 1, wherein the supporting elements are non-rigid.
3. A self-contained spring to mass support arm according to either of claims 1 and 2, wherein the support elements comprise of either a first standard spring, or a spring exhibiting zero-free length behaviour.
4. A self-contained spring to mass support arm according to claim 1 where the standard spring or zero-free length spring, is physically located within the support arm or preceding support structure.
5. A self-contained spring to mass support arm according to claim 1 whereby a spring is connected to a straight-line mechanism, with that straight line mechanism contained within a partially or fully revolute elbow joint.
6. A self-contained spring to mass support arm according to claims 2-4, whereby all supporting elements are so arranged as to provide static equilibrium of the support arm at any position within the range of movement of the support arm and limitations of the springs used.
7. A self-contained spring to mass support arm that has no parallelogram or pantograph geometry.Amendments to the claims have been filed as follows Claims 1. A self-contained spring to mass support arm comprising: a pivoted balance forearm with a mass; an upper arm; an elbow containing a straight-line mechanism allowing pivotal movement of the forearm; and a spring contained in a housing located within the forearm or the upper arm, wherein the spring is arranged to remain centralised within its housing during displacement of the forearm.2. A self-contained spring to mass support arm according to claim 1, wherein the supporting elements are non-rigid.3. A self-contained spring to mass support arm according to either of claims land 2, wherein the support elements comprise of either a first standard spring, or a spring exhibiting zero-free length behaviour.o 4. A self-contained spring to mass support arm according to claims 1-3, whereby all supporting c, elements are so arranged as to provide static equilibrium of the support arm at any position within the range of movement of the support arm and characteristics of the springs used.