SETTING DEVICE

Description

Technical field:

[0001] The invention relates to setting tools for driving nails and bolts, preferably hand-held setting tools for driving nails and bolts. More specifically, the invention relates to a setting tool according to the preamble of claim 1. Such a setting tool is described, for example, in WO 2020 / 259870 A1. Background:

[0002] Electrodynamic setting devices with linear drives ("electrodynamic setting devices") are known which utilize the repulsive interaction between a first excitation coil and a movable electrical conductor, wherein the movable electrical conductor directly or indirectly drives a driving element. The movable electrical conductor can be a squirrel-cage rotor or a second electrical coil, which is preferably connected electrically in parallel or, more preferably, in series with the first electrical coil.

[0003] An overview of the state of the art can be found in the following publications: US6830173B2, WO2018 / 104406, WO2021 / 001196, WO2020 / 126366, WO2019 / 233851, WO2019 / 233852, WO2019 / 233846, WO2019 / 233848, WO2019 / 233849, WO2019 / 234091, WO2019 / 233845, WO2019 / 233840, WO2019 / 233841, WO2019 / 233856, WO2019 / 233843, WO2019 / 233844, WO2021 / 122270, WO2021 / 122313, WO2021 / 122325, WO2021 / 122294, WO2021 / 122351, WO2021 / 122230, WO2021 / 122228, WO2020 / 259870. Summary: Technical problem:

[0004] After a setting process, the movable electrical conductor(s) must be returned to a known initial starting position.

[0005] For setting machines with moving coils, it is known to contact the moving coils with sliding contacts. However, these are subject to considerable wear and their impedance reduces the efficiency of such setting machines.

[0006] The present invention aims to enable the simple resetting of the movable electrical conductor in setting devices of this type after a setting operation. Furthermore, it aims to enable direct electrical (i.e., galvanic) contacting of the movable coil in such setting devices with a movable electrical coil, without the use of sliding contacts. Solution:

[0007] This problem is solved by a setting device according to claim 1. The setting device comprises: at least one housing and an electrodynamic drive, wherein the electrodynamic drive comprises at least one first excitation coil, a movable electrical conductor, for example a squirrel-cage rotor or a second coil movably arranged in the setting device, a driving element, a cable, a tensioning device for the at least one cable, comprising at least one spring element and a force-redirecting means, wherein the at least one force-redirecting means is preferably designed as a movable roller, which further preferably has a groove for receiving the cable, a stop and a stator, characterized in that the cable is attached on the one hand directly or indirectly to the movable electrical conductor and on the other hand directly or indirectly to the housing of the setting device.and that, in the rest state of the setting device, the cable is tensioned by the tensioning device through a preload of the spring element, in order to hold the movable electrical conductor in a rest position defined by the stop, and wherein, during a setting operation, the spring element is further tensioned over the cable by the movement of the movable electrical conductor, after which (i.e., after the setting operation) the spring element springs back to a preload and pulls the movable electrical conductor back into its rest position.

[0008] The reduced mass of the clamping device, including the cable, is preferably at most half and preferably at most one-quarter of the sum of the masses of the movable electrical conductor and the driving element. The reduced mass can be represented by mred = m1m2 / (m1 + m2) of the individual masses of the clamping device, e.g., as the harmonic mean of the individual masses. The work performed by the drive manifests itself predominantly as kinetic energy, distributed between the piston mass (including the electrical conductor) and the reduced mass mred of the clamping device.

[0009] The setting device is preferably a hand-held setting device.

[0010] Furthermore, a cable for the setting device according to the invention is disclosed, in which the movable electrical conductor is designed as a movably arranged second coil, wherein the cable has at least two conductors and one or more means for radial strain relief, for example in the form of a sheathing of the cable, to absorb repulsive Lorentz forces between the at least two conductors. The conductors must preferably be located as close together as possible so that the self-induction of the cable does not compromise the efficiency of the drive, because its initial self-induction (starting position) is very low, since the self-inductions of both coils largely cancel each other out.

[0011] The cable preferably features axial strain relief, which can be attached directly or indirectly to the housing of the setting device and to the movable second coil. This prevents the conductors (preferably highly flexible stranded wire) from stretching. In other words, it prevents the electrical conductors (wires) themselves from having to withstand the considerable tensile forces.

[0012] The cable is further preferably characterized in that its impedance is lower, and preferably at least five times lower, than the impedance of a series connection of the first excitation coil and the movable electrical coil when the drive is in its rest position. This allows the reactive power to be reduced to an acceptable level. In particular, it prevents the setting energy from being reduced by the area enclosed by the supply line (for the same conductor length). Brief description of the drawings:

[0013] Fig. 1a shows an exemplary embodiment of a drive in its rest position. Fig. 1b shows an embodiment of the drive during a setting process with a more tightly tensioned spring. Detailed description:

[0014] The invention can be understood as relating to the well-known "BX-3" nail-setting tools manufactured by HILTI, the basic operating principle of which can be found, for example, in DE 10 2005 000 089 A1. This class of tool first tensions springs using an electric motor. To set the nail, a release mechanism is activated, causing the springs to release abruptly and drive the driving element.

[0015] In BX-3 devices, the springs do not directly drive the driving element, but rather via a transmission formed by a roller mechanism (known in English-speaking countries as a "spring belt mechanism"). During a setting operation, the springs in BX-3 devices relax, and the potential energy from the springs is initially converted into the kinetic energy of the driving element via the roller mechanism.

[0016] The present invention works in exactly the opposite way.

[0017] A setting device according to the invention comprises at least a housing; a drive comprising at least: a first excitation coil; a movable electrical conductor, for example a squirrel-cage rotor or a coil movably arranged in the setting device; a driving element (e.g. a setting piston); a cable; a tensioning device for the at least one cable, comprising at least one spring element, wherein the spring may be, for example, a helical compression spring, a wave ring spring or a gas spring; a capacitor; a stop; and a stator.

[0018] The term "cable" is to be interpreted broadly; in this case, ropes, straps, belts, bands and chains are also to be considered cables.

[0019] In this context, a driving element, which may be designed in the manner of a piston, is understood to be a body movably arranged in the setting device, which can be accelerated directly or indirectly by a Lorentz force acting on the movable electrical conductor in order to set a nail directly or indirectly, also using its kinetic energy (and not only the kinetic energy of the movable electrical conductor).

[0020] The cable is attached directly or indirectly to the movable electrical conductor and directly or indirectly to the housing of the setting device. It is tensioned by the tensioning device, which may be designed as a pulley system. The tensioning device is arranged so that, by means of the spring element, it is able to pull the movable electrical conductor, via the at least one cable, into a first starting position (the rest position). In this position, the stop becomes effective and the distance between the movable electrical conductor and the first excitation coil is minimal. The stop can be adjustable and, for example, designed as a screw. Alternatively, it can be fixed and formed, for example, by the first excitation coil, its potting compound, the stator itself, the housing, or parts attached to the housing, such as an electromagnetic shield. Example of implementation

[0021] For better understanding, the invention is explained below using an example. This explanation is in no way intended to be restrictive, but merely to serve a better understanding of the invention.

[0022] Fig. 1a Figure 1 shows, for example, an embodiment of a drive in its rest position with a first excitation coil 111 and an associated movable coil 112.

[0023] The drawing can be understood based on the description in WO2020259870 and specifically Fig. 7. This drive comprises an iron circuit (also called a "flux concentrator"), i.e., a body made of soft magnetic material. The iron circuit preferably has a saturation flux density of at least 1 T, more preferably at least 1.5 T, and more preferably at least 1.9 T, and in particular an effective electrical conductivity of at most 10⁶ S / m, more preferably at most 10⁵ S / m, and more preferably at most 10⁴ S / m; various soft magnetic composite materials meet these requirements. Due to their brittleness, a soft magnetic composite material is preferably used for the iron circuit, which may be expertly segmented to prevent cracking. The segmentation thus serves the purpose of preventing a local exceedance of the tensile strength (and preferably also the yield strength) of the soft magnetic composite material during a setting process.

[0024] The drive piston is preferably made entirely or predominantly of a plastic, in particular a glass fiber-filled liquid crystal polymer, which may be configured to have at least one guide axis. More preferably, the drive piston is made entirely or partially of a technical ceramic that exhibits high mechanical toughness, high thermal conductivity, but low electrical conductivity, such as beta-Si3N4 or short-fiber-reinforced SiSiC.

[0025] The drive preferably has a setting piston with a piston rod, wherein driving energy is transferred from the setting piston to the nail via the piston rod.

[0026] A base plate preferably consists of soft magnetic solid material, in particular ferritic steel, which serves for shielding (EMC, EMCU) and as a heat sink.

[0027] A CFRP tube is preferably used for strain relief of the iron circle and for centering.

[0028] Furthermore, a tube made of an aluminum alloy can be provided, which preferably has the highest possible electrical conductivity and serves in this case to shield against alternating electromagnetic fields.

[0029] The tubular, soft magnetic material preferably exhibits a high saturation flux density and consists primarily of ferritic steel. It serves to shield against static electromagnetic fields.

[0030] To deal with the in Fig. 1aIn the symbolically depicted arrangement for driving a nail or bolt into a substrate, capacitor CI is first charged via switching converter SMPS (in the case of a battery-powered setting tool, this is done using electrical energy from the battery(ies) BAT). Capacitor CI should have the highest possible energy density, the lowest possible series resistance, and particularly high short-circuit withstand capability. Suitable capacitors are commercially available as film capacitors specifically designed for pulse applications.

[0031] Once the desired charging voltage is reached via C1, the thyristor SCR can be triggered to insert a nail. Current then flows through the conductors into the excitation coil and the movable electrical conductor (squirrel-cage rotor or coil). These are preferably connected in series, such that the current in the excitation coil and the movable electrical conductor flows in opposite directions during the insertion process, i.e., they repel each other. For the coils, flat copper wire is particularly suitable to achieve the highest possible fill factor with minimal electrical resistance.

[0032] The conductors (leads) 101 and 103 can be guided directly through the piston or its (rear) "guide axis"; preferably, the leads are made of an aluminum alloy or copper, particularly in the form of fine, highly flexible strands, and are strain-relieved outside the piston 720, for example, by means of carbon fibers or carbon fiber fabric. It is essential that the strain relief, which is mechanically connected in parallel with the leads, consists of a material with sufficient tensile strength—i.e., it does not tear under the given conditions—and has a higher tensile modulus than the electrical leads themselves, which it is intended to relieve. The strain relief is preferably designed to protect the electrical conductors from tensile stress (during or as a result of a settling process) that exceeds their yield strength or even their tensile strength. Furthermore, the strain relief material is preferably designed to have high specific strength.Carbon fibers and their fabrics can meet these requirements. The drive piston (first piston) can be designed to form a decoupling device with the setting piston (second piston) and cylinder.

[0033] Capacitor C1 can be charged from a battery, in particular a lithium-ion battery, using the switching converter SMPS, and discharged via the drive through the conductors 101 and 102 using the thyristor SCR, which exhibits pronounced ohmic-inductive behavior, which is why a freewheeling diode D1 is provided.

[0034] Conductor 101 is connected to the input of the first excitation coil 111, which is arranged and attached to the pot-shaped stator. A conductor is understood by those skilled in the art to be a single electrical wire (e.g., in comparison to the multiple conductors in a cable). A conductor is, for example, a stranded wire.

[0035] From the coil output, the conductor is routed as conductor 103 to a strain relief 107. Conductor 102 is routed directly from the surge current supply 100 to the strain relief 107.

[0036] Both conductors are then guided in a common cable 104, which is connected to strain relief 107 by form-fit, force-fit or material-fit connection, so that the introduction of mechanical tensile stresses into the first excitation coil 111 and impulse current supply 100 is prevented or at least reduced.

[0037] Cable 104 has at least two conductors that carry current at least temporarily during operation, which preferably consist of highly flexible copper or aluminum stranded wire and / or of single-layer or, preferably, multi-layer metal foils or metal films – namely the conductors 102 and 103. If a conductor consists of a multi-layer metal film or multi-layer metal foil, the individual layers are preferably insulated from each other, for example by an elastomeric polymer.

[0038] Wires 105 and 106 are preferably strain-relieved to reduce the introduction of tensile stresses into the moving coil. They are preferably routed within the armature rod to the coil to prevent tilting moments (at the piston). More preferably, they are additionally potted or bonded within the piston rod.

[0039] Cable 104 is designed such that conductors 102 and 103 are reliably electrically insulated from each other. Furthermore, cable 104 features its own radial strain relief: This radial strain relief absorbs the repulsive forces occurring between conductors 102 and 103 during energization of the drive and consists, for example, of the cable being wrapped with tensile-resistant fabric. Additionally, an abrasion-resistant sleeve can be shrunk or plated onto the cable.

[0040] Furthermore, cable 104 can include its own axial strain relief. Such intrinsic axial strain relief of cable 104 can, for example, consist of a third conductor made of tensile-resistant fabric or stranded wire, which preferably has a higher tensile modulus than the metallic conductor(s) selected for conductors 102 and 103. This axial strain relief can be connected to strain relief 107, so that tensile forces do not have to be transmitted entirely or predominantly via conductors 102 and / or 103.

[0041] Cable 104 is then guided over a force deflection device movably arranged along the setting direction, which in this example consists of a roller 108. However, instead of a roller, a cam disc could also be used, for example, on which cable 104 can slide. In this example, as mentioned, it is a roller which can have a groove to receive the cable, and in which the cable rests. Alternatively, unlike a groove, the roller 108 can have an outward curvature and be self-centeringly wrapped around the cable 104, which is then designed as a belt.

[0042] On the drive side, cable 104 is connected to strain relief 110. This does not necessarily have to be designed as a discrete component, but can, for example, also consist of the cable 104 being glued to the piston or another component connected to the movable coil 112, or otherwise mechanically connected (form-fit, material-fit or force-fit).

[0043] Starting from the strain relief 110, the two electrical conductors of cable 104 are connected to the input and output of the movable coil 112. This allows for a simple series connection of the stator coil 111, i.e., the first excitation coil, and the movable coil 112, such that they are energized in opposite directions when capacitor C1 discharges. Such a series connection is advantageous, but a parallel connection is also possible.

[0044] Spring element 109, for example a spiral compression spring, wave spring or gas spring, tensions the cable 104 via the movable roller 108 and, as long as no settling occurs, is able to move the movable electrical conductor, i.e. the movable second coil 112, into which in Fig. 1a to move to the starting position shown.

[0045] During a setting process, the first excitation coil 111 and the movable second coil 112 initially repel each other, thereby transmitting force via cable 104 to pulley 108 to tension spring element 109. Similar to a pulley system, a reduction occurs such that pulley 108 moves at (approximately) half the speed of the movable electrical conductor, corresponding to the reduction ratio.

[0046] Fig. 1b For better understanding, the diagram schematically shows the same drive during a setting process with a more tightly stretched spring.

[0047] After completion of the setting process, the movable electrical conductor, in this case the second coil 112, is pulled into its position via cable 104 until it reaches its stop. Fig. 1a The starting position shown was withdrawn.

Claims

1. Setting tool, comprising: at least one housing and an electrodynamic drive, wherein the electrodynamic drive comprises at least: - a first excitation coil (111); - a movable electrical conductor (112); - a driving element; - a cable (104); and characterised by - a clamping device for the at least one cable, comprising at least one spring element (109) and a means of force deflection (108); and - a stop; wherein the cable (104) is on the one hand attached directly or indirectly to the movable electrical conductor (112) and on the other hand attached directly or indirectly to the housing of the setting tool, and that in the idle state of the setting tool the cable is clamped by the clamping device through a preloading of the spring element (109) to keep the movable electrical conductor pulled into a resting position defined by the stop, and wherein, during a setting process, the spring element (109) is further tensioned via the cable (104) through the movement of the movable electrical conductor (112), after which the spring element rebounds to a preload and pulls the movable electrical conductor back to its resting position.

2. Setting tool according to claim 1, characterised in that a reduced mass of the clamping device, including the cable, is at most half and preferably at most a quarter of the sum of the masses of the movable electrical conductor and the driving member.

3. Setting tool according to claim 1 or 2, wherein the setting tool is a handheld setting tool.

4. Setting tool according to one of the claims 1 - 3, wherein the movable conductor (112) is a squirrel cage rotor or a second coil arranged movably in the setting tool.

5. Setting tool according to one of the claims 1 - 4, wherein the means of force deflection (108) is designed as a movable roller.

6. Setting tool according to claim 5, wherein the movable roller has a groove for receiving the cable.