WO2016174087A1

WO2016174087A1 - Spring element

Info

Publication number: WO2016174087A1
Application number: PCT/EP2016/059404
Authority: WO
Inventors: Martin Oskar Gustaf EWALDSSON; Carl Joakim GABRIELSSON; Johan Ingvast
Original assignee: Bioservo Technologies Aktiebolag
Priority date: 2015-04-29
Filing date: 2016-04-27
Publication date: 2016-11-03

Abstract

The invention concerns a spring element (1), for extending at least one joint of a body in use, being an elongated leaf spring having a length axis. The cross sectional shape is curved or bent around the length axis and the spring element has one stable position, which is in the extended position. The invention also concerns a glove (8) comprising such a spring element.

Description

SPRING ELEMENT

Technical field The present invention concerns a spring element for extending at least one joint of a body. Background art

Strengthening gloves are known, using different operating principles, such as arranging individual driving units on each finger to be strengthened or by using wires or cables, such as artificial tendons, in order to apply pushing and/or pulling forces onto particular points on each finger to be strengthened. For instance, electric or pneumatic driving mechanisms may be employed. One example of such a glove is described in US 8,029,414 B2, which proposes using artificial tendons fastened to strengthened fingers and driven by a central control unit in turn applying pulling forces to the tendons.

A person using such a glove may also have a problem of extending one or more fingers. Or it is also conceivable that the person only has a problem with extending one or more fingers. In WO 2012/036775 flat spring elements are arranged at a hand in order to extend the fingers.

Summary of the invention

The aim of the present invention is to provide a helping force to extend at least one joint of a body by means of a spring element, which at the same time disturb the flexing of the joint as little as possible. This could be a finger joint but it also conceivable to arrange a spring element according to the present invention at other joints of the body. Also at a joint of an animal. According to a first aspect of the invention a spring element for extending at least one joint of a body in use is provided. The spring element being an elongated leaf spring having a length axis and the cross sectional shape which is curved or bent around the length axis and the spring element has only one stable position, which is in the extended position. The spring element strives to reach the stable, extended position. The spring element is arranged at the joint of the body in order to support the extending of the joint, i.e. when the spring element is in use. An advantage of having a curved or bent cross sectional shape is that a constant flexing force is sufficient for a flexing of the joint of the body, irrespective the degree of flexing. The flexing movement is performed more or less crosswise of the length axis of the spring element. According to an embodiment of the spring element, the cross sectional shape has a curve with a greater radius or being flatter at a flex portion, when arranged at a joint of a body, i.e. in use, at the at least one joint than in the remaining element.

An advantage of that is that the initial force needed for starting the flexing of the spring element at the flex portion is decreased since the flatter shape of the flex portion decreases the buckling force needed compared to the curved or bent cross sectional shape of the remaining element.

According to another embodiment of the spring element, the cross sectional shape has a curve with a very large radius or is even flat at the flex portion at, in use, the at least one joint. The radius of the curve is at least as long as the width of the spring element. When the cross sectional shape is flat it is sufficient to use the normal flexing force without a need of overcoming an initial buckling force. According to another embodiment of the spring element, the flex portion has a length along the length axis, which is less than half the width of the spring element, in the stable position. According to an embodiment of the spring element, a flex portion is present at several joints, in use. If desired, at least one "bone" portion is bent around the length axis so much as it becomes reluctant to or withstands flexing forces in the "bone" portion. The "bone" portion may be a portion outside the flexing portion corresponding to a bone leading to a joint and the flexing portion corresponds to the joint itself. The portion of the spring element outside or between flexing portions may partly or fully be a "bone" portion.

According to another embodiment of the spring element, the spring element is provided with its cross sectional curvature centre towards the body, in use.

According to a further embodiment, the spring element may be stacked on at least one other spring element.

According to an embodiment the spring element is provided on top of and along at least one finger in a glove-like device, for extending the at least one finger. If desired, the width of the leaf spring is decreasing towards the free end of the finger when arranged at a joint of a body, i.e. in use.

According to a second aspect of the present invention a glove-like device having at least one spring element according to any of the previous embodiments described above is provided, where the spring element is arranged at, at least, one glove finger along its dorsal side. Preferably, the glove-like device is a strengthening glove for strengthening the grip of a user.

Short description of drawings

The present invention will now be described in more detail under referral to the appended drawings, in which: Fig. 1 shows an embodiment of a spring element having a curved or bent cross sectional shape in its, one and only, stable position.

Fig 2 shows an embodiment of a spring element provided with two flex portions having an increased cross sectional curve radius and a number of cross sectional views.

Fig. 3 shows an embodiment of a spring element arranged at a finger in a flexed position.

Fig. 4a-b shows two different embodiments of spring elements.

Fig. 5 shows a glove-like device comprising at least one spring element.

Fig. 6 shows a stack of spring elements in a bag-like device.

Fig. 7 shows a diagram of force -spring deflection curves.

Fig. 8 shows an embodiment of a spring element in different flexing positions.

Detailed description of embodiments In Fig. 1 a general embodiment of a spring element of the present invention is shown. The spring element 1 is an elongated leaf spring having a length axis 2. The cross sectional shape is curved or bent around the length axis 2. The cross sectional shape does not have to be a symmetrical curve with a constant radius but can be any type of curved or bent shape. This can be seen from the cross sectional views in Fig 2 taken at A-A, B-B and D-D, respectively showing a more symmetrical curve at A-A and D-D and a more bent cross section at B-B.

The spring element 1 has only one stable position, which is the extended position, as shown in the figure. The extended position does not have to be fully straight. It should be according to a suitable extended position of the joint to be extended. For example, the stable position may be slightly flexed if the spring element is arranged at a finger since a person usually has the fingers in a slightly flexed resting position, see Fig. 2.

Preferably the spring element 1 has at least one flex portion 3, which can be seen in Fig. 2 where two flex portions 3 are provided. The flex portion 3 has a cross sectional curve shape with a greater radius or being flatter or even flat at the flex portion 3 than in the remaining spring element 1. This can be seen in the cross sectional view taken at C-C at the flex portion 3.

The flex portion 3 is in use in line with the joint it is supposed to extend. The less cross sectional curvature the less initial force is needed for overcoming the buckling force so that the spring element becomes flat and flexes crosswise the length axis 2 and around the joint. The following force needed to continue the flexing movement is more or less constant.

In Fig. 7 force-spring deflection curves are shown. If a flat cross sectional shape, such as for a normal leaf spring, is used the force needed for flexing of the flat spring is direct proportional (a). If the cross sectional shape is curved a buckling force is needed to overcome but after that the flexing force is more or less constant for the continued flexing (b). According to a preferred embodiment the initial buckling force is reduced by the flexing portions having a flatter cross sectional curvature (c).

Preferably, the cross sectional shape has a curve with a very large radius or is even flat at the flex portion 3, which is indicated in the drawing with cross lines. The radius of the curve is at least the same as the width of the spring element 1. When the cross sectional shape is flat it is sufficient to use the normal (constant) flexing force without a need of overcoming an initial buckling force.

The length of the flex portion 3 in the direction of the length axis 2 is less than half the width of the spring element 1, in the stable position. During flexing the length of the flex portion 3 will increase, which may be seen in Fig. 3 compared to Fig. 2, which is indicated with three cross lines in Fig. 3 and one cross line in Fig. 2. In case of a body part having more than one joint, such as a finger, the spring element 1 may have a flex portion 3 in line with several or all joints, when the spring element is arranged at the body part, i.e. in use, for example by means of support device, such as a glove-like device 8. As can be seen in Fig. 3 two flex portions 3 are present in the spring element 1, which is provided at a finger with three joints. Preferably the cross sectional curvature centre is facing the body, as can be seen in Fig. 3. Although, it is possible to provide the spring element in the opposite direction as long as the spring element has a one stable position.

The embodiment of the spring element 1 shown in Fig. 3 and 5 has a "bone" portion 4 having a more pronounced bending around its length axis. In cross section it reminds more of a V than a C. Because of this pronounced bending this "bone" portion 4 may withstand much higher flexing forces than two bent outer portions 5, which are connected via the flex por- tions 3 at each end of the "bone" portion 4. The outer portions 5 are less bent around the length axis.

The flex portions 3 will propagate into the outer portions 5 during flexing but not inward the "bone" portion 4. If all portions between the flex portions 3 would be bent in a similar proportion to each other the flex portion propagation would be similar outwards of both sides of the flex portions 3.

It is of course possible to have a more pronounced bending forming a "bone" portion in any of the portions corresponding to a bone in use. Thus, in a spring element as shown in Fig. 3 also the outer portions may be "bone" portions or only one or two of the three portions may be "bone" portions.

Figure 8 illustrates a spring element 1 in three differently flexed states a, b and c where it is fully extended in state a and most flexed in state c. The spring element 1 has a flex portion 3 above a joint of a finger which can be seen because the spring is flattened there. The spring element 1 states are drawn on top of each other.

The stiffness of the spring is locally dependent of the curvature of the cross section. The stiffness is low where the section is flatter compared to where it is curved. When the spring element 1 is flexed, the flexing starts at the flattened part because it is less rigid there. The further the flex, the higher force is required and the smaller radius in the flattened portion, up to a specific force.

When the force is large enough, the curved cross sectional portion is starting to flatten out beginning from the flattened part. Because of the transition of the curved portion to a flatter or flat portion when increasing the flexion, the force will be more or less constant through the flexion.

Furthermore, since the force is more or less constant, the flexing radius will also be more or less constant through the different flexing states. The figure 8 illustrates this process where the radius of the flex portion is indifferent of flexing state.

It is also possible to have a decreasing width of the spring element towards the at least one end. The decreasing width decreases the flexing force needed for flexing the spring element 1.

The spring elements 1 may be stacked on top of each other in case a stronger spring element is desired, see Fig. 6. In this figure a bag-like device 9 is shown. The bag-like device 9 may also be used when only one spring element 1 is present, too.

In Fig. 4a-b different embodiments of inventive spring elements are shown. Different ways of providing the flex portion 3 will now be described. As can be seen from fig 2 and 3a, b the flex portions 3 may undergo a plastic flexing so that a residual change of cross sectional curvature will occur.

In Fig. 4a a piece 6 of flat material is attached crosswise the length axis. In the shown case one piece 6 is provided on only one side (the side facing the cross sectional curvature centre) or on both sides to urge the spring element to become at least flatter. The pieces 6 may for example be riveted, glued or screwed to the spring element 1. In Fig. 4b instead a buckling force may be applied through three, for example, hits or dot welds along the crosswise direction to join two spring elements 1 and thus achieve a flex portion 3.

It is also conceivable having another type of "bone" portion 4 where the "bone" portion 4 is covered, at least from the side facing the cross sectional curvature centre, but preferably on both sides of the spring element 1 with a flat piece of flex-reluctant material is fixed to the spring element 1. It is also conceivable to have a portion where the cross sectional curvature is arranged in the opposite direction in the "bone" portion.

The spring element 1 is preferably provided in a glove-like device 8 when it is supposed to support the extending of a finger, see Fig. 5. The glove-like device 8 may be a full glove or a partial glove and more than one finger may be provided with a spring element 1. The spring element 1 is provided on top of and along at least one finger in the glove-like device 8. Preferably, the spring element 1 is provided in a strengthening glove, which enhance the gripping of a person using the strengthening glove. Such strengthening gloves are for example using artificial tendons along at least one finger in the glove in order to be able to enhance flexing of the at least one finger. An example is shown in WO 2008/027002 of the same applicant.

The present invention has been shown in exemplifying embodiments but may be altered in many different ways within the scope of the appended claims.

Claims

1. A spring element (1), for extending at least one joint of a body in use, being an elongated leaf spring having a length axis (2), characterised in that the cross sectional shape is curved or bent around the length axis (2) and that the spring element (1) has one stable position, which is in the extended position, wherein the spring element (1) is provided on top of and along at least one finger in a glove-like device (8), for extending the at least one finger.

2. The spring element according to claim 1, wherein the cross sectional shape has a curve with a greater radius or being flatter at a flex portion (3), at the at least one joint than in the remaining element.

3. The spring element according to claim 2, wherein the cross sectional shape has a curve with a very large radius or is even flat at the flex portion (3) at, the at least one joint.

4. The spring element according to claim 2 or 3, wherein the flex portion (3) has a length along the length axis, which is less than half the width of the spring element, in the stable position.

5. The spring element according to any one of the previous claims, wherein a flex portion is present at several joints.

6. The spring element according to claim 5, wherein a bone (4) portion is bent around the length axis (2) so much as it becomes reluctant to or withstanding flexing forces in the bone portion (4).

7. The spring element according to any one of the previous claims, wherein the spring element (1) is provided with its cross sectional curvature centre towards the body.

8. The spring element according to any one of the previous claims, wherein the spring element (1) may be stacked on at least one other spring element.

9. The spring element according to claim 8, wherein the width of the leaf spring element (1) is decreasing towards the free end of the finger.

10. A glove-like device (8) having at least one spring element (1) according to any of the previous claims arranged at, at least, one glove finger along its dorsal side.

11. The glove-like device according to claim 10, wherein the glove-like device (8) is a strengthening glove for strengthening the grip of a user.