Adjustable shock absorber for a via ferrata set

Abstract

Fall arrestor for a via ferrata set 1 with a rope brake 3 serving as a friction brake, which acts on a strap 7 to slow the fall of a person P to be secured, wherein the braking effect of the rope brake is adjustable, characterized in that The rope brake consists of two brake elements 5a, 5b. and each of the brake elements 5a, 5b has a sawtooth profile, wherein the two brake elements 5a, 5b are arranged such that the sawtooth profiles are arranged complementarily to each other, and the tooth tips of the sawtooth profiles each have a rounded contour and are designed as band circumferential edges, the braking effect is generated via the wrap angle at the tooth tips and wherein the distance between the two brake elements 5a, 5b is continuously adjustable with an adjusting screw 4 in order to vary the wrap angle at the tooth tips, where the variation occurs at more than three spatially separated wrapping angles.

Description

[0001] The invention relates to an adjustable fall arrestor for a via ferrata set with a braking element serving as a friction brake, according to the preamble of claim 1.

[0002] People hiking or mountaineering are often secured using ropes. These ropes consist of twisted fibers and serve to transmit tensile forces. Flat braided ropes are also called straps or webbing.

[0003] In the following, the term rope is used not only for round ropes but also for straps or bands.

[0004] Via ferrata sets are used to secure people on via ferratas. Modern via ferrata sets typically have two carabiners (10a, 10b) attached to the ends of Y-shaped cable sections. A third cable section serves as a brake cable (7).

[0005] At the end of the brake rope, a locking mechanism (not shown) is typically provided, limiting the maximum braking distance to approximately 120 cm. A rope brake 3 acts on the brake rope 7 and is connected to the carabiner arms of the person being belayed, for example, via a webbing loop. The belayer is connected to the brake rope 7.

[0006] In alternative designs, the rope brake 3 can be connected to the person P to be secured via a connecting element, and the brake rope 7 can be connected to the carabiner arms.

[0007] In such systems, the brake rope and rope brake as a unit are referred to as a shock absorber.

[0008] To secure the person (mountaineer or hiker), the two carabiners 10a, 10b are attached to the wire rope 12 of the via ferrata.

[0009] In the event of a fall, the fall is slowed and stopped by the action of the rope brake.

[0010] The rope brake thus acts as a shock absorber. According to standard EN958, the maximum braking force must not exceed 6 kN.

[0011] The acceleration acting on the person being secured depends on the person's body weight and the impact force. For a standard weight of 80 kg, the impact force is limited to a maximum of 6 kN, resulting in tolerable accelerations. However, lighter individuals may experience higher acceleration forces due to their lower mass, which can be undesirable.

[0012] Various shock absorbers with adjustable braking effect are known.

[0013] Fall arresters with adjustable braking force are described in DD248737 A1 (1986) and WO 2006 / 103259 A1. In DD248737 A1 (1986), this is achieved via a rope that is compressed to varying degrees between a stop and an adjustable eccentric, depending on the setting. In the event of a fall, the rope can be pulled out of the brake with more or less resistance. WO 2006 / 103259 A1 describes two brake shoes that, via an adjusting screw, compress the brake rope between them to a greater or lesser degree, thereby braking the fall with a higher or lower impact force.

[0014] These solutions have the following disadvantages: 1. In both cases, only a friction-generating element is used on the brake cable. This results in extremely high loads on the brake cable at that one point. Damage to the brake cable typically occurs, and the residual breaking strength of the entire system is significantly reduced. 2. When testing such a shock absorber, the generally non-critical value of 6 kN according to standard EN 958 must not be exceeded. Friction-based systems only function reliably once static friction is overcome and sliding friction occurs. Due to the strong compression of the rope and the associated increase in static friction at a single point, the initial force peak on the falling mass (the person) is very high (see force curve in [reference]). Fig. 5). 3. Precise and continuous adjustment of the braking force is extremely difficult to achieve. WO 2006 / 103259 A1 does not address this problem at all; it merely states that the value can be changed. DD248737 A1 solves the adjustment problem using various control windows in which the incremental adjustment can be read. 4. Both systems change the normal force when the braking force is adjusted, according to the formula: FRmax=μH⋅FN This implies that the normal force has a cumulative effect on the frictional force. Therefore, a very high contact pressure on the brake cable is required to increase the braking force of the system.

[0015] The solutions mentioned above therefore exhibit the following significant disadvantages.

[0016] The braking force cannot be adjusted to the weight of the person being secured. The brake shoes subject the brake cable to constant, localized stress (leading to long-term stability issues, deformation, and cable crushing).

[0017] The object of the invention is therefore to provide a fall arrester for a via ferrata set that does not have these disadvantages, that in particular allows easy adjustment to the weight of the person to be secured, that ensures long-term stability, that does not lead to permanent point loading of the brake rope, that minimizes the initial impact peak in friction-based systems and that is easy and inexpensive to manufacture.

[0018] This problem is solved by the features specified in independent claims 1, 7 and 8.

[0019] Advantageous further developments of the invention are specified in the dependent claims.

[0020] The invention is explained in more detail below using various exemplary embodiments.

[0021] They show: Fig. 1 via ferrata set with a fall arrestor according to the invention Fig. Figure 1 shows a via ferrata set 1 with Y-shaped rope sections. One rope section serves as a brake rope 7 on which a rope brake 3 acts. The rope brake 3 essentially consists of a housing 2 and two brake elements 5a, 5b. The brake element 5a is mounted so that it can be moved. An adjusting screw 4 is used for this movement. A falling person is indicated in the black circle. Fig. 2 Rope brake of a fall arrester according to the invention in different views. Fig. 3 Sectional view of the arrangement of the braking elements according to a first alternative of a shock absorber for two different settings light person / heavy person In Fig. Figure 3 shows the relative position of the brake cable 7 and the brake elements 5a, 5b for adjusting the braking force for individuals of different weights. The brake elements 5a, 5b have a polygonal contour. The different wrap angles at which the brake cable 7 wraps around the brake element 5a and 5b, respectively, are clearly visible. The wrap angle can be continuously changed using the adjusting screw 4. Fig. 4. Sectional view of the arrangement of the braking elements according to a second alternative of a shock absorber for three different settings: light person / medium person / heavy person In Fig. 4 is not an entire brake element that is slidably mounted, but only a sub-element that can be moved using adjusting screw 4. Here too, the braking force can be continuously adjusted via the wrap angle. The adjusting screw 4 can also be connected to a display that shows the user the set braking force. Fig. 5. View of a fall arrestor according to the state of the art. Here, a perforated plate 5c is provided as a rope brake. Depending on the weight of the person, the brake rope 7 is threaded through more or fewer of the openings (numbered 1-10). Fig. 5a Schematic representation of the arrangement of a known shock absorber according to Fig. 5 for three different settings: light person / medium person / heavy person. As can be seen from the diagram, the wrap angle and thus the braking force can only be varied in discrete increments. Fig. 6 Typical force-time diagram for a fall of the person being secured with conventional friction-based shock absorbers with a strong initial impact peak. Fig.7. Via ferrata set with two combined rope brakes. The energy absorber consists of two rope brakes 3 and 3a. Rope brake 3 can be a conventional rope brake or a rope brake according to the invention.

[0022] With the shock absorber according to the invention, the braking force can be easily adjusted to the weight of the person.

[0023] Furthermore, the brake cable is only subjected to tension in the event of a fall. Impact peaks are avoided. Due to the shape of the brake elements, the braking effect does not engage immediately but with a minimal delay. 1. There is no rope pinching, only an increase in friction due to an increase in the overall wrap angle (Euler-Eytelwein formula). This results in less damage to the brake cable. 2. Friction is not generated at a single point, but rather at numerous deflections connected in series along the brake cable, where friction is generated by wrapping around the cable. The brake cable is never completely taut between these points when at rest. Additionally, PA or another thermoplastic with high elongation is used as the material for the brake cable. This prevents all friction-generating points from being stressed simultaneously; at each point, the static friction can first be overcome, followed by sliding friction at that point, then static friction at the next point, and so on. Because the total static friction of the entire system is not overcome all at once, but rather in stages, a force peak on the falling mass can be avoided. 3. Sliding friction: Because the wrap angle α is a power term in the Euler-Eytelwein formula, even a small change in the angle has a very strong effect on the generated braking force. The adjustment is made without generating any force in the system.

[0024] The gravity steam generator according to the invention guarantees optimal steaming over a wide weight range of the mass to be braked. Further advantages include: - High safety, high final strength due to the material-friendly passage of the brake element 7 through the rope brake 3 - Simple, precise and effortless adjustment of the braking force - Reduction of impact force through gradual overcoming of the adhesive force

Claims

[1] Fall arrester for a via ferrata set 1 with a rope brake 3 acting as a friction brake on a strap 7 to slow the fall of a person P to be secured, the braking effect of the rope brake is adjustable, characterized by , that The rope brake consists of two brake elements 5a, 5b. and each of the brake elements 5a, 5b has a sawtooth profile, wherein the two brake elements 5a, 5b are arranged such that the sawtooth profiles are arranged complementarily to each other, and the tooth tips of the sawtooth profiles each have a rounded contour and are designed as band circumferential edges, the braking effect is generated via the wrap angle at the tooth tips and wherein the distance between the two brake elements 5a, 5b is continuously adjustable with an adjusting screw 4 in order to vary the wrap angle at the tooth tips, where the variation occurs at more than three spatially separated wrapping angles.

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