ES2938323T3 - forearm crutch - Google Patents

Abstract

The invention relates to a forearm crutch (1), comprising a support tube (2) with a contact surface (3) at the bottom, a handle (12) protruding from the support tube (2) at the direction of walking and a forearm. clamp (13) or sleeve to guide the forearm, where the handle (12) and the forearm (13) or sleeve are integrated into a profiled upper part (10) that closes the support tube (2) in its upper part, and where the handle (12) the opposite side of the profiled top (10) is designed as a contact surface (15) when the crutch (1) rests against a wall or furniture (16), where a rocking axis (18) passing through the center of gravity (19) of the crutch (1) and through the contact surface (3) at a longitudinal coordinate (h) measured along the axis of balance (18) at the region of the upper molded part (10) at a distance (d(h)) runs in front of the contact surface (15) in the direction of travel, the upper molded part (10) having in the area of the contact surface (15) a cross section traversed perpendicularly by the rolling axis (18), to which a circumference of maximum radius (r(h)) can be rewritten in such a way that it has at least two points of contact with the cross section of the axis, separated from each other. support surface (15), and throughout the section at each longitudinal coordinate (h) between the longitudinal coordinate (h1) at the level of the handle (12) and the longitudinal coordinate (h2) at the level of the forearm clamp (13) or cuff: rh-dh >ε> 0, with ε>=1mm, for example ε>=2mm, preferably ε>=5mm, or ε>=10mm. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

forearm crutch

The invention relates to a forearm crutch comprising a support tube with a ferrule on the underside, a handle that protrudes from the support tube in the direction of travel, and a forearm clamp or part arranged above the crutch. handle for guided reception of the forearm, the handle being, as well as the clamp or forearm part, integrated in one piece forming an upper part that ends the support tube at the top, the opposite side of the shaped upper part being able to serve to the grip as a supporting surface when the forearm crutch is resting on a wall or piece of furniture.

A generic forearm crutch is disclosed in utility model specification DE 202006010 732 U1. Addressed here is the problem that such a forearm crutch very often tends to fall off when it is left standing somewhere. Accordingly, it is proposed in this document to provide the upper part of the forearm crutch with a lining made of a material with good adhesion to the surface, neoprene or cellular rubber being recommended in particular as lining material.

The above inventing company thus prevents a generic forearm crutch from slipping laterally. However, there is another reason that supported forearm crutches fall off. This second reason is due to the reduced size of the ferrule at the lower end of the support tube. On the one hand, this surface is relatively small, about 2 to 5 cm2, and, in the case of a slightly inclined forearm crutch, only the marginal edge is in contact with the ground. As a consequence, a supported crutch only has an unstable balance and even if it does not slip at the upper contact point, it can still roll laterally around the greatly reduced lower contact zone and eventually fall. This effect cannot be avoided even with a non-slip coating on the upper end of the support tube.

In this case, a distinction must be made between two different support situations: on the one hand, a forearm crutch can be supported on a wall or any other vertical surface, in which case only the upper edge of the forearm crutch comes into contact with the wall or surface, especially in the area of a brace or forearm piece. In order to prevent slipping and/or falling in this case, it has already been proposed to provide two lateral rubber pads at the height of the clamp, cf. DE 10308044 A1.

On the other hand, it probably happens frequently that there is no wall or vertical support surface, for example, when someone sits at a table in the middle of a restaurant room. There, the crutch can often only be supported on the edge of a table or, at best, on the back of a chair. In this case, the upper edge of the forearm crutch does not come into contact with the edge of the table or the back of the chair, but with an area located below the brace or forearm piece and, therefore, also below the rubber pads provided for in document DE 19308044 A1, so that in these cases the pads cannot prevent the fall of the crutch either. In addition, the forearm crutch often has a cylindrical geometry at the height of the upper plastic part or the support tube and is therefore prone to roll or slide laterally and eventually to fall off.

Document DE20209938U discloses a forearm crutch that has all the technical features set forth in the preamble of claim 1.

One of the drawbacks of the described state of the art is the problem that gives rise to the invention to improve a generic forearm crutch in such a way that it does not tend to slide laterally or to roll or tilt on the contact surface on the underside (especially even in case of leaving it resting on an edge that develops approximately horizontally, for example, of a piece of furniture).

This problem is solved in a generic forearm crutch thanks to the fact that a balance axis, which passes through the center of gravity of the forearm crutch and through the tip, with a longitudinal coordinate h measured along the balance axis, is develops in front of the support surface at a distance d(h) in the direction of travel in the area of the upper shaped part, the upper shaped part having in the area of the supporting surface a cross section perpendicular to the axis of rolling in which a perimeter with a maximum radius r(h) can be circumscribed, in such a way that it presents at least two points of contact, separated from each other, with the cross section of the support surface, and applying to the entire section at each longitudinal coordinate h between the longitudinal coordinate h1 at the height of the grip and the longitudinal coordinate h2 at the height of the clamp or forearm piece:

r(h) - d(h) > £ > 0,

being £ > 1 mm, for example £ > 2 mm, preferably £ > 5 mm, or £ > 10 mm, gradually increasing the horizontal distance between two marginal edges, which laterally limit the support surface, from the height of the handle up to the height of the brace or forearm piece.

The invention firstly defines a roll axis which extends on the one hand through the bottom side of the tip, for example through its center point or through its trailing edge area and, on the other hand , through the center of gravity of the forearm crutch. This center of gravity can, for example, be determined experimentally, on the one hand, balancing the support tube aligned horizontally with the handle pointing downwards on a cutting edge or edge that develops transversally to it, in order to find the height of the center of gravity along the longitudinal axis of the tube support and, on the other hand, balancing the handle aligned horizontally on the edge or cutting edge that also develops transversally to the handle, so that the support tube adopts a vertical position to determine the position of the center of gravity in the direction marching. In such a case, the actual center of gravity lies along the support tube at the predetermined height and in the direction of the handle, approximately parallel to the direction of travel, ahead of the support tube by the predetermined amount . This forward movement is due to the fact that, at the upper end of the holding tube, both the handle and the clamp or forearm piece respectively project forwards, thereby shifting the center of gravity forwards.

The invention has further shown that it is precisely this position of the center of gravity in front of the support tube that is responsible for the unstable position of a supported forearm crutch. This is because, in the case of a supported forearm crutch, the thus defined axis of balance is tilted backwards similar to the support tube, so in case the supported forearm crutch tilts slightly to the side over its upper contact point in the area of the support surface, the center of gravity is also shifted to the side and, in this case, lowers its height in relation to the ground as a result of the inclination of the support tube . This releases more energy, which in turn feeds the lateral rocking motion of the supported forearm crutch and thus leads to an unstoppable, even accelerated, continuation of the rocking motion. Therefore, in a generic forearm crutch this movement does not stop until the crutch has finally fallen off.

However, the invention now provides for a special configuration of the cross section of the plastic upper part in the region of the rear bearing surface of a forearm crutch, namely such that the radius r(h) of a circumscribed great circle around the cross section, which nevertheless still has at least two points of contact with the cross section of the support surface, is greater than the distance d(h) between the roll axis and the support surface at height h . Such a dimensioning has the consequence that, in the event of a lateral rocking or inclination of the forearm crutch at the height h, the distance between, on the one hand, the axis of rocking and, on the other hand, the point contact or back support. Consequently, if the support tube is slightly tilted, the center of gravity moves upwards, which requires energy. This energy is taken from the kinetic energy of the rocking or oscillating movement and thus this movement slows down and eventually stops. The unstable balance has now been converted to a stable balance (the forearm crutch according to the invention no longer falls).

Since the contact surface configured according to the invention extends over the entire height h between, on the one hand, the forearm clamp or piece and, on the other hand, a handle, the forearm crutch can be supported along of all this height on a horizontal edge, for example, of a piece of furniture, that is, for example, on a table edge or on the back of a chair or on the upper edge of a chest of drawers, etc., without risk of let it fall

In addition, it is even possible to provide that the contact surface configured according to the invention extends over the entire length of the height h of the rear side of an upper part that integrates, on the one hand, the brace or forearm part and, on the other part, the hilt. This provides maximum safety against accidental falls.

It has been found to be advantageous if the two lateral edge edges of the support surfaces extend laterally in regions next to the support tube. This measure makes it possible to give the bearing surface between the two marginal edges an almost arbitrary horizontal transverse curvature, in order to fulfill the condition according to the invention.

The invention can be further developed by virtue of the fact that the two lateral edge edges of the supporting surface develop symmetrically, on the one hand, to a plane spanned by the longitudinal axis of the support tube and, on the other hand, to a plane spanned by the longitudinal axis of the grip. In this case, the support surface can be configured symmetrical to a vertical central plane pointing in the direction of travel, which also helps to locate the center of gravity of the forearm crutch in this central plane and to minimize the tendency to lean laterally. .

The horizontal distance between the two marginal edges can correspond in the area of the handle approximately to the diameter of the tube holder. In this way, the forearm crutch does not widen in this area and remains manageable.

According to the invention, the horizontal distance between the two marginal edges gradually increases from the height of the grip to the height of the forearm piece or clamp.

The higher a fulcrum is located, the further away the center of gravity of the forearm crutch is from this fulcrum in the horizontal direction and thus the more unstable the respective position is. To compensate for this increased instability, the support surface can be widened upwards so that the stable zone is larger.

Based on these considerations, the horizontal distance between the two marginal edges in the region of the brace or forearm part should be at least approximately half the width of the brace or forearm part.

Within the framework of the invention it is understood that the radii of curvature of the marginal edges are equal to or less than 20 mm, for example equal to or less than 10 mm, preferably equal to or less than 5 mm, in particular equal to or less than 2 mm . These marginal ridges can be quite pronounced as long as there is no risk of injury. The smaller the radius of curvature in question, the wider the actual bearing surface can be with otherwise the same total width of the assembly.

The invention allows an improved variant in that the lateral edge edges are configured raised relative to the inner region of the support surface. As a result, the bearing surface can be concave in cross section or even have a trough-shaped or even window-shaped cavity. When supporting such a forearm crutch, the actual contact points are in the area of the marginal edges.

In principle, the invention allows configurations such that a horizontal cross section through the bearing surface between the two edge edges is, at least in some areas,

a) flat, or

b) concavely curved, or

c) convexly curved with a radius of curvature corresponding to at least half the length of the handle, preferably corresponding to at least the entire length of the handle, especially corresponding to at least twice the length of the handle handle. In all these cases the relationship according to the invention between the radius of curvature of the support surface and the distance from the roll axis is fulfilled.

Within the framework of a first preferred embodiment of the invention, the bearing surface can extend without interruption between the two edge edges. In this case, it is a comparatively simple construction, furthermore shifting the center of gravity of the forearm crutch backwards as a result of the extension according to the invention that acts as a counterweight for the handle, thereby improving the stability criterion according to the invention. the invention.

On the other hand, it is also possible for the support surface to have at least one recess between the two marginal edges. By means of a recess, the weight can be reduced, so that the forearm crutch is lighter as a whole. On the other hand, the areas close to the lateral marginal edges of the support surface are the most important for the stability criterion according to the invention, since these are effective when the inclined forearm crutch rotates slightly around an axis approximately parallel to the balance axis, finally forming the same real axis of rotation and resulting in such a case decisive for the stability of the position. The area between these marginal edges is, on the other hand, of secondary importance and, for this reason, can be omitted. In the best of cases, it is necessary to ensure that the recess is symmetrical to a central plane encompassed by the handle and the support tube, in order to minimize the risk of a rocking moment when leaving the forearm crutch supported.

At least one such recess can be in the form of a groove running vertically and flanked on both sides by two halves of the supporting surface. With a recess in the form of a groove that completely divides the support surface into two halves in the vertical direction, a maximum weight reduction can ideally be achieved.

Thanks to another possible improved variant of the invention, the at least one recess is configured as an upwardly open groove limited by the bearing surface at the bottom and on both sides. Especially if the lateral edge edges of the widening supporting the support surface diverge upwards, two remaining edge zones converge downwards similar to an open "V" at the top.

Finally, it is also possible to design the at least one recess as a trough-shaped cavity surrounded on all sides by the frame-like bearing surface. In this way, in particular, despite the reduction in weight, it is also possible to connect the lateral edge regions to each other both at the lower end and at the upper end, in order to achieve maximum stability.

A forearm crutch according to the invention has a further improvement in stability due to the fact that the support surface consists of a material with a rough surface structure. Thus, such a forearm crutch can rest on smooth surfaces, even if these are made of stainless steel or smooth concrete, glass, tiles, natural stone, coarse fiber, wood or plastic, or irregular and artistically designed ceramic tiles. As an additional measure, the contact surface can be made of a friction-increasing material, such as an elastomer, or coated with such a material. It is even possible to imagine a fabric covering or a soft padding for the support surface, so that it can be adjusted to the wall or the edge of the piece of furniture in question.

The support surface or, in particular, a widening of the supporting plastic upper part can be designed as a counterweight to the forward-pointing handle and/or be provided with a counterweight for this purpose. In the case of a construction like this, the center of gravity of the entire assembly moves towards backwards against the direction of travel and therefore moves closer to a furniture edge or the wall when the forearm crutch is resting, which promotes stability in order to prevent the forearm crutch from falling. The invention also provides for the support surface to be made in one piece with the forearm crutch. Together with the handle and a clamp or forearm part, this can be configured as a common plastic upper part, for example. In such a case, it can be manufactured within the framework of a single injection-moulded part.

On the other hand, it is also possible for the support surface to be manufactured separately and to be or can be attached to the forearm crutch, for example by means of adhesive, a Velcro fastener, screws, etc. Such an attachment technique also allows conventional forearm crutches to be retrofitted in accordance with the present invention.

According to the invention, further provision is made for the support surface to be provided with a reflector that is preferably directed to the rear. However, instead of integrating the reflector into the support surface itself, it may be preferable to arrange it next to, below or on top of the support surface itself, so that its stability with respect to side slipping is not negatively influenced.

Instead of or in addition to a reflector, the support surface can be provided with a rearward-directed light source, so that the forearm crutch can be clearly seen in the dark. It can also be advantageous not to integrate this light source directly into the support surface, but to place it next to, above or below it.

Finally, the invention reveals the possibility of arranging a battery or an accumulator in the handle or in the support tube to power the light source. A compartment for the battery or accumulator can also be arranged in a rearwardly directed enlargement that supports the actual support surface.

Further features, details, advantages and effects based on the invention result from the following description of a preferred embodiment of the invention as well as from the drawing. In this case it is shown in the:

Figure 1 a conventional forearm crutch in a side view;

Figure 2 a first embodiment of a forearm crutch according to the invention in a side view; 3 shows the embodiment of the invention according to FIG. 2 in a perspective view obliquely from behind, the supporting tube being shown in fragments;

Figure 4 a section through Figure 2 along the line IV-IV;

Figure 5 a second embodiment of the invention in a view corresponding to figure 3; and

Figure 6 a third embodiment of the invention in a view corresponding to figure 3.

A forearm crutch 1 consists of a support tube 2 with a cap 3 on the underside for resting on a floor 4 or another base.

Preferably, the ferrule 3 forms part of a base part 5 configured, for example, as a cap made of rubber or a comparable material that is placed on the lower end of the support tube 2.

The support tube 2 itself can be configured in one piece or be telescopically extensible.

In the latter case, it is made up of a lower tube 6 and an upper tube 7, whose longitudinal axes 8, 9 develop concentrically with respect to one another. One of the two tubes 6, 7 (in most cases the upper one) has a slightly larger diameter and accommodates the other tube so that it can be moved in the longitudinal direction.

In the case of a telescopically extendable support tube 2 a height adjustment is provided, ie a possibility to lock the two tubes 6, 7 in different intermediate positions.

An interlocking possibility can be realized, for example, by configuring one of the two tubes 6, 7 (preferably the outer tube 7) with several perforations each at different heights, a radially guided pin being able to engage in the other tube 6 ( preferably inside) and pressed out by means of a spring. By pressing this pin into the corresponding bore, the tubes 6, 7, initially nested into each other, can be displaced relative to each other and then locked next to each other again in a new position by locking. of the pin in another hole.

A stepless adjustment and/or locking possibility could be realized with a screwing and/or clamping technique, the interlocking ends of the two parts of the telescopic support tube 2 being able to be configured in such a way that they can be adjusted between each other. yes and lock with interlocking threaded sections and/or with a clamping device.

At the upper end of the support tube 2 there is a plastic upper part 10, which is preferably configured as a molded part, in particular as an injection molded part, which has a stem 11 that extends the support tube 2 upwards with a handle. 12 that protrudes laterally from it in the lower area of the stem and with a clamp 13 or forearm piece arranged in the upper area of the stem for guided reception of the forearm.

The grip 12 usually faces forwards in the direction of travel and may be ergonomically designed with recesses for each finger and/or configured with a reflector at the forward end. Preferably, the handle 12 is inclined slightly forwards, eg rising at an angle of 10° to 30° with respect to the horizontal.

The brace 13 can have two lateral arms 14 that surround the forearm of the person concerned on both sides; a forearm piece could be closed in the form of a ring and thus completely encircle the forearm of the person concerned.

Preferably, for ergonomic reasons, the stem 11 of the plastic upper part 10 is inclined slightly backwards with respect to the support tube 2, for example at an angle of 10° to 30°. The plane spanned by the two arms 14 of the clamp 13 or the plane spanned by the ring of a forearm part is preferably traversed perpendicularly by the longitudinal axis of the stem 11 of the upper plastic part 10, so that in particular the two arms 14 of the clamp 13 extend upwards in the direction of travel.

A rearwardly directed reflector can also be arranged at the upper end of the brace 13 or forearm piece.

By leaving the forearm crutch 1 resting, the upper area on the rear side of the plastic upper part 10 opposite the handle 12 pointing in the direction of travel serves as a support surface 15 on a wall or piece of furniture 16, especially in a song 17 of the same.

In the embodiment 1' according to the invention according to FIG. 2, the support surface 15' is configured in a special way in order to prevent the forearm crutch 1' from falling when resting on a piece of furniture 16, especially on a horizontal upper edge 17 thereof.

For this purpose, a rocking axis 18 is defined in particular, which connects the tip 3 on the ground side to the center of gravity 19 of the forearm crutch 1'. Since the center of gravity 19 is normally close to the longitudinal axis 8, 9 of the support tube 2, the roll axis 18 can coincide with said longitudinal axis 8, 9 or develop at a small distance from it, in which latter case The roll axis 18 and the longitudinal axis 8, 9 of the support tube 2 meet or intersect in the region of the nose piece 3.

A height h is defined along the roll axis 18, the zero point of which is at the point of contact of the tip 3 with the ground 4.

Preferably, the support surface 15' extends in the direction of the longitudinal coordinate h between a first height hn, where the longitudinal (central) axis of the handle 12 intersects the rear side of the upper part 10, and a second height h2 , where a plane encompassed by the longitudinal (central) axes of the two lateral arms 14 of the bracket 13 intersects the rear side of the upper part 10. On the other hand, it is also possible for the support surface 15' to extend along the length of the entire height h of the rear side of the top piece 10.

Furthermore, in the area of the support surface 15', at each height h along the roll axis 18, a section plane Q(h) is defined through the support surface 15' which is traversed perpendicularly by the rocking axis 18 and that includes the point of contact of the support surface 15' with the edge 17.

As can be seen in FIG. 3, the actual bearing surface 15' is limited by two lateral edge edges 20, the radius of curvature of these edge edges 20 being relatively small, that is to say, for example, on an order of magnitude of 1 mm to 20mm.

The cross section through the support surface 15' within the section plane Q(h) follows, especially between the marginal edges 20, a curve that can be circumscribed by at least one circle and that touches the curve in question in at least one circle. minus two contact points far from each other, for example in the area of the two edge edges 20.

The largest circle K that can be circumscribed on this curve can be degenerated into a straight line that practically corresponds to a circle with an infinitely large radius, provided that such a straight line still has two points of contact, one separated from each other. another, with the contact surface 15'.

Now, a prerequisite for a stable position of the forearm crutch 1' on the edge 17 of the piece of furniture 16 is that, within the section plane Q(h), the distance v between the rocking axis 18 and the edge 17 of the piece of furniture 16 or with respect to the point of contact between the support surface 15' and the edge 17 of the piece of furniture 16 (if the forearm crutch 1' is aligned so that the handle 12 points outward from the edge 17 at most) is smaller than the radius R of the largest circle that can be circumscribed around the support surface 15' at the height h in question.

In this case, if the forearm support 1' rolls laterally along the furniture edge 17, the roll axis 18 is forced to rise more steeply, whereby the center of gravity 19 should shift upwards. As a consequence of this elevation of the center of gravity 19, the potential energy would increase and the quantity of The energy in question would be taken from an eventual kinetic energy originated by the movement, thus slowing down the swinging movement and finally ending it, thus finding the forearm crutch 1' a stable equilibrium and not an unstable equilibrium as in the case of a forearm crutch 1 commercial.

As can be seen in FIG. 3, the edge edges 20 can follow the course or the width of the upper plastic part 10 at the respective height h. In this case, the support surface 15' would be narrower in the lower area of the upper plastic part 10 and wider in the upper area. Here, a widening such as this can be made continuous or be greater in some sections than in others. In particular, in the embodiment according to FIG. 3, the widening takes place mainly in the upper region, that is to say approximately at the height of the clamp 13.

In the embodiment 1' according to FIG. 3, the support surface 15' is closed, ie free of interruptions.

In FIG. 4 a cross section through this closed bearing surface 15' can be seen. It can be seen that this surface presents a convex curvature in cross section. This convex curvature in cross section can follow a circular line K or be approximated by a segment of a circular line K, the circular line K being defined by the position of its center point M, as well as by its radius r.

In figure 4, the intersection point P between the circular line K and the radius r has also been joined to the intersection point of the roll axis 18 through the corresponding section plane; this line of union is identified with the letter h. From the distance d between the center point M of the circular line K and the balance axis 18 it is possible to calculate the length of the connecting line v as a function of the angle of inclination a of the vertical plane of symmetry S of the crutch of forearm 1' with respect to the edge 17 of the piece of furniture 16, being:

v = [(r - d)2 4 * r * d * sin2 (a / 2 ) ] /

Since the sine function is monotonically increasing near the zero point of the argument, this also applies to the square of the sine function, specifically, starting equally from the zero point in both directions.

In other words, if a deviates from 0° in any direction, the length v increases, since r and d are constant. However, for each a, v indicates respectively the distance of the axis of balance 18 with respect to the edge 17 of the piece of furniture and, consequently, also the height of the center of gravity of the forearm crutch 1'.

As a consequence, if the forearm crutch 1' rolls laterally through an angle a, the height of its center of gravity always increases, which requires energy. Therefore, the forearm crutch 1' is capable of absorbing a certain amount of energy before falling off. Thus, the forearm crutch 1' is stable with respect to lateral torsions.

The decisive criterion for this is that the center point M of the circular line K always lies in front of the point of intersection of the balance axis 18 through the corresponding section plane, especially to a dimension d > 0 or even to a dimension d >> 0.

This increased stability against tilting or lateral slipping of the forearm crutch 1' can also be achieved with other geometries of the support surface 15'. For this purpose, the support surface 15' can also have openings such as windows or slots. The only criterion is that on the circular line K there are two points P separated from each other that can be connected to each other by a circular line K of radius r, such that the radius r is greater than the distance d between the center point M of the circular line K and the point of intersection of the roll axis 18 through the section plane.

This gives rise to the fact that, with each inclination (that is, with each increase in angle a), the roll axis 18 straightens, raising the center of gravity located in the roll axis 18. Conversely, at angle a = 0°, the center of gravity assumes the lowest position, thus stabilizing this orientation of the forearm crutch 1'.

As can be seen in FIG. 2, the support surface 15' in the upper area of the upper plastic part 10 of the forearm crutch 1' is displaced to the rear in relation to the balance axis 18, that is to say, against it. of the direction of travel. This means that with the same radius r of the circular line K of the transversely convex curvature, the center point M of the circular line K also shifts backwards until possibly the aforementioned stability criterion, according to which the center point M of the circular line K must lie in front of the point of intersection of the balance axis 18 through the corresponding section plane, it can no longer be fulfilled in the upper region of the support surface 15'. An effective countermeasure against instability such as this when the forearm crutch 1' is in contact with the upper area of the support surface 15' consists in calculating the radius of curvature r for the entire support surface 15' as a function of the position of the balance axis 18 in the upper region of the support surface 15', so that the entire support surface 15' can follow a cylindrical skin surface with a sufficiently large radius r, or by not selecting the radius of curvature r constant for the entire support surface 15', otherwise adapt it to the position of the rocking axis 18 at the corresponding height; This last option would give rise, for example, to a conical support surface 15' that widens from bottom to top, corresponding to a cone supported at the tip.

In contrast, in the embodiment 1" according to FIG. 5, the support surface 15" has a bowl-shaped or window-like recess 21 that is completely surrounded by the remaining frame-like part of the support surface 15" closed of a window.

On the other hand, in the embodiment 1(3) according to FIG. 6, the bearing surface 15(3) is interrupted by a slot-shaped notch 22 open at the top and surrounded laterally, as well as below, by the part remaining support surface 15" similar to a U-shaped frame.

Within the framework of another embodiment not shown, this notch 22 in the form of a slot could even completely pass through the support surface 15(3), whereby the support surface 15(3) would be divided into two separate halves, one of which other.

Regarding the stability criterion explained in relation to figure 4, according to which the center point M of a circular line K describing or approximating the support surface 15', 15", 15(3) must be located in front of the axis of In the embodiments according to FIGS. 5 and 6, when viewed in the direction of travel, a suitable circular line must be sought which approximates the remaining bearing surface 15", 15(3) traversed by interruptions or recesses. For this purpose, the curvature of the remaining webs of the supporting surface 15", 15(3) can be used or, if necessary, also a straight line joining the two rearmost edges of the two 15" halves, 15( 3). In such a limiting case of a straight line, the center point M is at infinity and, although this is not mandatory, it can be assumed with respect to the stability criterion according to the invention that this center point M is infinitely far ahead. of the roll axis 18, so a connecting line like this meets the stability criterion. Consequently, a transverse curvature with the largest possible positive radius of curvature is always sought, the center point of which is located in front of the roll axis 18; in case of such an approximation, only a concordance in at least two points separated from each other is required. A bisection of the bearing surface 15", 15(3) as in Figures 5 and 6 always meets this criterion, since a straight joining line can always be found here that meets these requirements.

In the present invention, the rocking axis 18 can coincide with the longitudinal axis 8, 9 of the support tube 2 or, preferably, be located behind said longitudinal axis 8, 9, whereby the possibility of further reducing the distance between the swing axis 18 and the edge 17. This can be achieved by arranging the support surface 15, 15', 15", 15(3) on the rear side of a widening 23 of the upper plastic part 10, 10' , 10", 10(3). The weight of this widening 23 shifts the center of gravity 19 backwards, that is to say, in the direction of the support surface 15, 15', 15", 15(3).

Such a flare 23 can optionally be integrated with the plastic upper piece 10, 10', 10", 10(3) or made as a separate piece that can be attached later to a forearm crutch 1, 1', 1", 1 (3) existing. In this case, the attachment of such a separate widening piece 23 to the upper plastic piece 10, 10', 10", 10(3) of the forearm crutch 1, 1', 1", 1(3) It can be done in various ways, eg by adhesive, a Velcro fastener, screws, etc.

The actual support surface 15, 15', 15", 15(3) of the forearm crutch 1, 1', 1", 1(3) can be made of a non-slip material or provided with a non-slip coating, for example , made of rubber or the like, and/or may be provided with a non-slip structure, for example, with a groove or corrugation, or with knots, etc.

Also in the case of a rearwardly offset support surface 15, 15', 15", 15(3), a forearm crutch 1, 1', 1", 1(3) can be provided with a reflector, for example, in a section above the support surface 15, 15', 15", 15(3).

Reference list

1 forearm crutch

2 Support tube

3 ferrule

4 floor

5 Base piece

6 tube

7 tube

8 longitudinal axis

9 longitudinal axis

10 Plastic top piece

11 stem

12 handle

Clamp

Arm

Support surface

Furniture

Singing

roll axis

Gravity center

fringe edge

cutout

Notch

widening

Claims (15)

1. Forearm crutch (1) comprising a support tube (2) with a ferrule (3) on the underside, a handle (12) projecting from the support tube (2) in the direction of travel, as well as a clamp (13) or forearm piece arranged above the handle (12) for the guided reception of the forearm, the handle (12) being, as well as the clamp (13) or forearm piece, integrated in one piece forming a upper part (10) that ends the support tube (2) at the top, and configuring the side of the shaped upper part (10) opposite the handle (12) as support surface (15) when the forearm crutch (1) leans against a wall or a piece of furniture (16), a) Developing in front of the support surface (15) a balance axis (18) that passes through the center of gravity (19) of the forearm crutch (1) and through the tip (3) in a longitudinal coordinate ( h) measured along the swing axis (18) in the area of the upper shaped part (10) at a distance (d(h)) in the direction of travel, b) presenting the upper shaped part (10), in the area of the support surface (15), a cross section perpendicularly traversed by the rocking axis (18) and around which a circle with a maximum radius ( r(h)), so that it has at least two contact points, separated from each other, with the cross section of the support surface (15), characterized by c) throughout the section at each longitudinal coordinate (h) between the longitudinal coordinate (hn) at the height of the handle (12) and the longitudinal coordinate (h2) at the height of the clamp (13) or forearm piece, applies: r(h) - d(h) > £ > 0, where £ > 1 mm, for example £ > 2 mm, preferably £ > 5 mm, or £ > 10 mm, d) gradually increasing the horizontal distance between two marginal edges (20), which laterally limit the support surface (15), from the height of the handle (12) to the height of the clamp (13) or forearm piece. 2. Forearm crutch (1) according to claim 1, characterized in that the support surface (15) extends along the entire longitudinal extension (h) of the upper part (10), applying continuously along the length of the upper part (10). along the entire longitudinal extension (h) of the upper part (10) in each longitudinal coordinate (h): r(h) - d(h) > £ > 0, where £ > 1 mm, for example £ > 2 mm, preferably £ > 5 mm, or £ > 10 mm. Forearm crutch (1) according to claim 1 or 2, characterized in that the two lateral marginal edges (20) of the support surface (15) develop at least in areas laterally close to the support tube, preferably developing the two lateral marginal edges (20) of the support surface (15) symmetrically to a plane encompassed, on the one hand, by the longitudinal axis (8, 9) of the support tube (2) and, on the other hand, by the axis length of the handle (12). Forearm crutch (1) according to one of claims 1 to 3, characterized in that the horizontal distance between the two edge edges (20) in the area of the handle (12) corresponds approximately to the diameter of the support tube (2 ) at that point. Forearm crutch (1) according to one of Claims 1 to 4, characterized in that the horizontal distance between the two edge edges (20) in the area of the clamp (13) or forearm part is at least approximately half of the width of the brace (13) or forearm piece. Forearm crutch (1) according to one of claims 1 to 5, characterized in that the radii of curvature of the marginal edges (20) are equal to or less than 20 mm, for example equal to or less than 10 mm, preferably equal to or less than 5 mm, especially equal to or less than 2 mm. Forearm crutch (1) according to one of claims 1 to 6, characterized in that the lateral edge edges (20) are configured elevated relative to the bearing surface (15). Forearm crutch (1) according to one of Claims 1 to 7, characterized in that a horizontal cross section through the bearing surface (15) between the two edge edges (20) is at least in areas a) flat , either b) concavely curved, or c) convexly curved with a radius of curvature corresponding to at least half the length of the handle (12), preferably corresponding to at least the entire length of the handle (12), corresponding in particular to at least the double the length of the handle (12). Forearm crutch (1) according to one of claims 1 to 8, characterized in that the bearing surface (15) extends without interruption between the two edge edges (20). Forearm crutch (1) according to one of claims 1 to 9, characterized in that the support surface (15) has at least one recess between the two edge edges (20). 11. Forearm crutch (1) according to claim 10, characterized in that the at least one recess a) It is configured as a groove that develops in the vertical direction and is flanked on both sides by two halves of the support surface (15), or b) it is configured as a slot open towards the top (22) and limited by the support surface (15) at the bottom as well as on both sides, or c) It is configured as a bowl-shaped cavity (21) surrounded on all sides by the frame-like support surface (15). Forearm crutch (1) according to one of the preceding claims, characterized in that the support surface (15) a) consists of a material with a rough surface so that it cannot slip on smooth surfaces, such as smooth concrete, rough fibreboard, tiles, glass, natural stone, wood, plastic, stainless steel or tile ceramics of artistic and irregular design, and/or b) consists of a friction-increasing material, such as an elastomer or is coated with such a material. Forearm crutch (1) according to one of the preceding claims, characterized in that the support surface (15) is designed as a counterweight to the forward-pointing handle (12) and/or is provided with a counterweight. Forearm crutch (1) according to one of the preceding claims, characterized in that the support surface (15) a) is configured in one piece with the forearm crutch (13), or b) is manufactured separately and is attached or can be attached to the forearm crutch (13). Forearm crutch (1) according to one of the preceding claims, characterized in that the support surface (15) a) is fitted with a reflector, and/or b) It is provided with a rearward-directed light source, preferably a battery or accumulator being provided for its power supply in the handle (12) or in the support tube (2).