ELECTRODYNAMIC DRIVE

Description

[0001] The present invention relates to a nail-setting device with a electrodynamic drive. State of the art:

[0002] Pyrotechnic or pneumatic devices are used in various technical fields because electromagnetic drives are unsuitable in these areas. The following are particular exclusion criteria for electric drives: Insufficient force and / or work capacity per drive mass or drive volume in highly dynamic electric direct drives such as so-called Thomson coils and railguns, as well as their high circuitry effort and / or insufficient efficiency.

[0003] This is illustrated by various examples: Nail-driving tools, and in particular hand-held nail-driving tools, in which, for example, a piston is accelerated by the combustion of an ignitable gas mixture or a propellant charge to drive a nail. Arc flash protection devices, in which a pyrotechnically driven metallic bolt penetrates an insulating plate and causes a short circuit in order to dissipate energy from an arc flash. Short-circuit current limiters, in which a pyrotechnic charge destroys a metal tongue, so that the short-circuit current commutates from the path of the metal tongue to a parallel-connected fuse or choke.

[0004] From US 6,830,173 B2, a nail-setting device with an electrodynamic drive according to the preamble of claim 1 is known.

[0005] ABB's patent application WO2015172824 A1 discloses an electrodynamic drive for a high-voltage switch. This application features an actuator based on a Thomson coil, comprising a primary coil and a flux concentrator surrounding the primary coil. The flux concentrator is made of a soft magnetic or soft ferromagnetic material, such as iron, magnetic steel, or a material like Permadyne.

[0006] Publication US 1 819 139 A shows a striking device with a rotor mounted so as to be slidable along its axis of rotation, which performs a back-and-forth movement by means of a cam disk.

[0007] Publication GB 2 079 381 A shows a drive for a gas pump.

[0008] The inventive task is therefore to improve a nail-setting device with an electrodynamic drive.

[0009] This problem is solved by a nail-setting device with an electrodynamic drive according to claim 1. Preferred embodiments of the present invention are the subject of the dependent claims.

[0010] The present invention comprises a nail-setting device with an electrodynamic drive, wherein the drive comprises: a first excitation coil, a soft magnetic frame, and a squirrel-cage rotor mounted to move along an axis, wherein the frame has a saturation flux density of at least 1.0 T and an effective specific electrical conductivity of at most 10⁶ S / m, wherein preferably the first excitation coil and / or the frame have at least one strain relief means. The saturation flux density is the flux density at which the differential permeability dB / dH of a material becomes equal to the magnetic constant, i.e., at which the dimensionless relative permeability µr assumes the value µr = 1 due to magnetic saturation. In particular, this is a highly dynamic electrodynamic drive, especially constructed in the manner of a Thomson coil with a soft magnetic frame.

[0011] In one possible embodiment, the excitation coil has a winding height that is greater than its length, which is therefore flat.

[0012] In one possible embodiment, the excitation coil is arranged in the soft magnetic frame and supported against it.

[0013] In one possible embodiment, the frame represents an open magnetic circuit which has an outer region, a bottom and an inner region, and which is open at the front, wherein the first excitation coil at least partially encloses the inner part of the frame, and wherein the squirrel-cage rotor, in its initial stroke position, plunges into the front opening of the frame and thereby at least partially encloses the inner part of the frame.

[0014] In one possible embodiment, the squirrel-cage rotor is designed as a hollow cylinder at least on its side facing the first excitation coil and / or the frame is constructed in the manner of a pot magnet.

[0015] In one possible embodiment, the soft magnetic frame is formed entirely or predominantly from a soft magnetic composite material and / or one or more sheet metal stacks.

[0016] The present invention thus comprises in particular a nail-setting device with an electrodynamic drive, in particular a highly dynamic electrodynamic drive, in particular constructed in the manner of a Thomson coil with a soft magnetic frame, comprising: a first excitation coil whose winding height is greater than its length, i.e., which is flat; a soft magnetic frame in which the first excitation coil is arranged and against which it is supported, and which, in particular, in the manner of a pot magnet, represents an open magnetic circuit having an outer region, a bottom and an inner region, and which is open at the end face, wherein the first excitation coil at least partially encloses the inner part of the frame; a squirrel-cage rotor, preferably hollow-cylindrical at least on its side facing the first excitation coil, movably mounted along an axis, which in its initial stroke position plunges into the opening at the end face of the frame and thereby at least partially encloses the inner part of the frame.It is provided that the frame is formed entirely or predominantly from a soft magnetic composite material or one or more laminated cores, which has a saturation flux density of at least 1.0 T, preferably at least 1.3 T, particularly preferably at least 1.5 T, and an effective specific electrical conductivity of at most 10⁶ S / m, and that the first excitation coil and / or the frame have at least one means for strain relief, in particular in the form of an enclosure.

[0017] The strain relief preferably absorbs at least some of the radial forces occurring at the first excitation coil during an adjustment process, perpendicular to the direction of movement. In the electrodynamic drive, the Lorentz force acting on the squirrel-cage rotor is preferably used to perform work.

[0018] In one possible embodiment, the space between the outer and inner areas of the frame, into which the squirrel-cage rotor dips, has the shape of a cylindrical shell, its longitudinal axis corresponding to the direction of movement of the drive and the winding axis of the coil(s).

[0019] In one possible embodiment, the frame, made of a soft magnetic composite material, is composed of several parts and / or segments. These multiple parts and / or segments can be bonded or cast together.

[0020] The frame is preferably composed of several parts and / or segments in such a way that the occurrence of tensile stresses is reduced at least to the extent that breakage of the frame and / or its parts during operation is avoided.

[0021] In one possible embodiment, the squirrel-cage rotor of the drive is made entirely or partially of a non-magnetic material, preferably of an electrically conductive and non-magnetic material, in particular of a hardenable aluminum alloy.

[0022] In one possible embodiment, the squirrel-cage rotor has a ring of electrically conductive material, for example copper, on its bottom side, i.e. in the initial stroke position on the side of the squirrel-cage rotor (40) facing the first excitation coil (30).

[0023] Preferably, the ring is embedded in the squirrel-cage rotor and in particular in the non-magnetic material of the squirrel-cage rotor and / or connected to the squirrel-cage rotor by a material-locking and / or form-locking connection.

[0024] In one possible embodiment, the specific conductivity of the ring is at least 50% of that of pure copper (%IACS).

[0025] The ring can be made of, for example, pure copper, a copper or aluminum alloy, or a copper-based composite material.

[0026] In one possible embodiment, the ring has a dimension of at least I = sqrt (t * ) in the direction of movement, either entirely or predominantly. rho / pi * µ ) where t is the half-power width of the current in the excitation coil during a rated actuation operation, rho where is the specific electrical resistance of the ring, pi is the circle constant, and µ is the magnetic constant.

[0027] In one possible embodiment, the squirrel-cage rotor and / or a piston driven by the squirrel-cage rotor is formed wholly or partially from a hardenable aluminum alloy, which is further preferably in a hardened state.

[0028] In one possible embodiment, the squirrel-cage rotor and / or a piston driven by the squirrel-cage rotor is formed wholly or partially from a hardenable aluminum alloy which, in the hardened state, has a specific electrical conductivity of > 25% that of pure copper (%IACS).

[0029] In one possible embodiment, the electrodynamic drive is at least partially operated by means of a capacitor discharge. Preferably, at least one capacitor is discharged via the first excitation coil to actuate the drive.

[0030] Preferably, the capacitor discharge is brought about by switching one or more semiconductor switches, wherein the semiconductor switch is preferably a thyristor.

[0031] The semiconductor switch can be protected from damage during operation by a saturating inductor connected in series with it, by dimensioning the saturating inductance to sufficiently limit the initial current rise rate dl / dt.

[0032] The drive preferably comprises a capacitor arrangement with at least one capacitor. The capacitor(s) are preferably one or more electrolytic and / or film capacitors. Preferably, the capacitor arrangement includes at least one film capacitor.

[0033] The capacitor arrangement preferably stores between 0.1 kJ and 10 kJ of energy, and more preferably more than 0.3 kJ.

[0034] The capacitor arrangement preferably has a capacitance between 0.1 mF and 20 mF and / or a series resistance (Electrical Serial Resistance) between 0.1 mOhm and 100 mOhm.

[0035] In one possible embodiment, the electrodynamic drive can include a lifting magnet or be operated on one, wherein the armature of the lifting magnet, which can be formed, for example, from a part of the frame, such as the base itself, transmits an impulse to the squirrel-cage rotor during an adjustment process by means of a predominantly elastic impact, in order to accelerate it, and wherein a capacitor discharge via the first excitation coil is carried out synchronously with the elastic impact.

[0036] In one possible embodiment, the highest voltage applied to the excitation coil during an adjustment process is at most 600V, preferably at most 500V, and more preferably at most 450V. In this case, an electrolytic capacitor is preferably used to operate the drive.

[0037] In one possible embodiment, the highest voltage applied to the excitation coil during an adjustment process is between 1 kV and 2 kV. This allows for improved efficiency. In this case, a film capacitor is preferably used to operate the drive.

[0038] In one possible embodiment, at least the predominant part of the frame has an effective specific electrical conductivity of less than 10^5 S / m, preferably less than 10^4 S / m.

[0039] In one possible embodiment, the material of the frame has a saturation flux density B s > 1.5 T, preferably B s > 1.75 T, more preferably B s > 1.9 T, wholly or predominantly.

[0040] In one possible embodiment, the first excitation coil is designed to reduce the influence of the skin effect by forming the windings from several individually insulated conductors instead of a solid single conductor, similar to a stranded wire, and / or by using a flat wire.

[0041] In one possible embodiment, the first excitation coil has a copper fill level of at least 30%, preferably at least 40%, more preferably at least 50%, and more preferably at least 60%. In particular, the copper fill level is between 70% and 85%.

[0042] In one possible embodiment, the first excitation coil is potted and additionally strain-relieved by fiber reinforcement against the (Lorentz) forces acting during an adjustment process.

[0043] In one possible embodiment, strain relief is achieved in the form of a cylindrical enclosure of the coil made of a fiber-reinforced composite material within the outer area of ​​the frame.

[0044] In one possible embodiment, the strain relief is designed in the form of an enclosure, and preferably consists of an enclosure that at least partially surrounds the drive and / or frame.

[0045] The enclosure is preferably made of a material with a tensile strength of more than 700 MPa, preferably more than 1400 MPa.

[0046] In one possible embodiment, a fiber composite material and / or a maraging steel can be used for the enclosure.

[0047] In one possible embodiment, the housing has the form of a hollow cylinder whose axis coincides with the axis of movement of the drive. The housing can be closed at the bottom, i.e., on the side facing the base of the frame, for example, similar to a pot. Alternatively, the housing can be open on the side facing the base of the frame.

[0048] In one possible embodiment, the leads to the first excitation coil are twisted. Alternatively or additionally, the leads to the first excitation coil can be formed like a coaxial cable, consisting of a closed outer conductor and an inner conductor, and these need not be rotationally symmetrical. In another possible embodiment, the leads to the first excitation coil are designed as flat wires that lie against each other without any significant gap; that is, they or their insulating sheaths touch or define an insignificant gap, in particular an air gap, between them. "Insignificant" here means that the additional self-induction with which the leads are affected by the gap is small compared to the minimum self-induction of the drive, which depends on its operating state.

[0049] In one possible embodiment, the electrodynamic drive has a cylindrical housing made of a fiber composite material and comprising a first fabric of carbon fiber, a second fabric of one or more electrically insulating materials, for example glass, HPPE or aramid fiber, and a plastic matrix, wherein, in the manner of so-called ring cores, the electrically insulating fabric is used as an insulating intermediate layer between windings of carbon fiber fabric to dampen eddy currents caused by alternating electromagnetic fields.

[0050] In one possible embodiment, the electrodynamic drive comprises a piston which is driven by the squirrel-cage rotor. The squirrel-cage rotor can preferably be rigidly connected to the piston and / or formed integrally with it. However, the squirrel-cage rotor can also have a driver through which it acts on the piston, which is formed separately from the squirrel-cage rotor.

[0051] When the electrodynamic drive is triggered, the front end of the piston can act on a target to transfer the work done by the drive.

[0052] Preferably, the piston is slidably mounted at least on one side, preferably in the area of ​​its front end.

[0053] Preferably, the drive includes a return mechanism for the squirrel-cage rotor and / or the piston, which returns the piston and / or the squirrel-cage rotor to an initial stroke position after the drive is triggered. Preferably, the return mechanism is designed to exert a holding force on the piston and / or the squirrel-cage rotor in the initial stroke position. In one possible embodiment, the return mechanism operates using a permanent magnet.

[0054] In one possible embodiment of the present invention, a rear end of the piston passes through an opening in the frame. Preferably, the drive in this case has a return mechanism for the squirrel-cage rotor and the piston, which exerts a return force on the rear end of the piston.

[0055] The piston can be made in one piece or in multiple pieces. In a multi-piece design, the individual parts are not necessarily, but preferably, rigidly connected to each other.

[0056] The reset device is preferably arranged on the side of the frame facing away from the squirrel-cage rotor.

[0057] The return mechanism may include a sliding bearing for the rear end of the piston.

[0058] Preferably, the restoring force is generated by a permanent magnet.

[0059] Preferably, the rear end of the piston is made of a soft magnetic material. The rear end of the piston can be made of a laminated core and / or have slots to reduce eddy currents.

[0060] Furthermore, the return mechanism for generating the return force can include one or more permanent magnets. In particular, the return mechanism preferably comprises an arrangement of a plurality of permanent magnetic elements and / or permanent magnetic areas that form a magnetic circuit which is increasingly closed as the piston returns to its original position, by the rear end of the piston increasingly entering a recess in the arrangement. In particular, the arrangement can have the form of a hollow cylinder.

[0061] The arrangement can still form a Halbach array.

[0062] In one possible embodiment of the present invention, the drive comprises a capacitor arrangement and a switch, wherein closing the switch causes a discharge of the capacitor arrangement via the excitation coil, by which the squirrel-cage rotor and / or the piston are accelerated from their initial stroke positions.

[0063] Further preferred embodiments of a nail-setting device according to the invention with an electrodynamic drive as described above are presented below.

[0064] According to the invention, the term "nail" does not require a specific shape. In particular, the term "nail" also includes bolts, pins, etc. However, in the present application, a nail is specifically a fastening element with a pin-shaped section.

[0065] In one possible embodiment, the hand-held nail-setting device further comprises: at least one capacitor, at least one electrochemical energy storage device, at least one switching converter, at least one switch, one piston, a reset device for the squirrel-cage rotor and the piston, In order to set a nail, the capacitor is first charged with electrical energy from the electrochemical energy storage device using the switching converter, whereupon the switch is closed to cause a discharge of the capacitor via the excitation coil, whereupon the squirrel rotor and the piston are accelerated from their initial stroke positions, and the piston is used to drive in the nail, and after which the resetting device is used to return the piston and the squirrel rotor to their initial stroke positions.

[0066] In one possible embodiment, the electrodynamic drive exhibits a maximum force density of more than 100 kN / l, preferably more than 200 kN / l, and more preferably more than 300 kN / l, during a design actuation process, in each case based on the volume of the electric drive. The maximum force density is to be understood as the quotient of the maximum Lorentz force acting on the squirrel-cage rotor and the volume of the electrodynamic drive. The electrodynamic drive comprises and consists, in particular, of the frame, the winding space of the excitation coil, and the portion of the squirrel-cage rotor that is immersed in the frame.

[0067] Preferably, the volume of the electrodynamic drive is defined as the sum of the volumes of the frame, the winding space of the excitation coil, and the portion of the squirrel-cage rotor that extends into the frame. If the squirrel-cage rotor does not extend into the frame, the volume of the electrodynamic drive is preferably defined as the sum of the volumes of the frame and the winding space of the excitation coil.

[0068] In one possible embodiment, the electrodynamic drive exhibits a maximum force density at the force maximum during a design-compliant positioning process.

[0069] In one possible embodiment, the hand-held nail setting device is designed or has an additional device such that when the drive is reset, i.e., when the squirrel-cage rotor and piston are reset to their respective initial stroke positions, mechanical contact between the squirrel-cage rotor and the first excitation coil is prevented.

[0070] Preferably, an adjustable stop for the squirrel-cage rotor and / or piston is provided, particularly in the form of a screw passing through the frame. In particular, the frame itself or a strain relief of the frame serves as the stop.

[0071] In one possible embodiment, the setting energy of the nail setting device, in particular the setting energy achievable by charging the capacitor(s), is ≥ 10J, preferably ≥ 100J, more preferably ≥ 200J.

[0072] The at least one capacitor is preferably a film capacitor or a foil capacitor.

[0073] In one possible embodiment, the hand-held nail setting device has an electrolytic, film or foil capacitor, the housing of which is at least partially formed by the housing of the setting device itself, so that the winding of the capacitor does not have a completely independent housing.

[0074] Preferably, the housing of the setting device in the area of ​​the winding is metallic and is further preferably made of an aluminum alloy.

[0075] The housing of the setting device may have a structured surface in the area of ​​the winding, particularly in the form of a heat sink.

[0076] In one possible embodiment, the electrochemical energy storage device is a battery.

[0077] In one possible embodiment, the at least one switch is a semiconductor switch, in particular a thyristor.

[0078] The present invention will now be described in more detail with reference to exemplary embodiments and drawings.

[0079] This shows: Fig. 1 a longitudinal section through a first embodiment of a drive used according to the invention, Fig. 2 a detailed longitudinal section view of a second embodiment of a drive according to the invention, showing only one half of the rotationally symmetrical structure, Fig. 3 several axial sections through segments from which the soft magnetic frame in the Fig. 1 The embodiment shown is constructed in Fig. 4a to d), a further embodiment of a drive according to the invention with a resetting device and Fig. 5 an embodiment of a nail setting device according to the invention.

[0080] The following explanations serve to provide a better understanding of the invention; they are to be regarded solely as examples and in no way as limiting.

[0081] Fig. 5 shows an embodiment of a nail-setting device according to the invention with a drive such as that described in Fig. 1 and / or 4 is shown in more detail. Before discussing the specific embodiment of the nail-setting device in more detail, embodiments of the drive used in the nail-setting device will first be described in more detail.

[0082] In contrast to the aforementioned application by ABB, the frame (10), designed as a "flux concentrator," is formed in the exemplary embodiment of the drive from a soft magnetic composite material (hereinafter: SMC, for "soft magnetic composite") and / or from one or more soft magnetic laminated cores, which has a saturation flux density of at least 1.5 T and an effective specific electrical conductivity of at most 10⁶ S / m. Preferably, the frame is formed from an SMC with a specific conductivity < 10⁴ S / m, a saturation flux density Bs ≥ 1.9 T, and a maximum relative permeability µr ≥ 50. Furthermore, the frame material(s) should be selected with regard to strength requirements to possess a high yield strength. SMCs well suited for the implementation of the invention are known and available under the brand name Somaloy.

[0083] To date, SMCs do not achieve the high saturation flux densities of known magnetic iron-cobalt alloys (e.g., Vacoflux). However, given the high dynamics targeted by the invention and for which it is intended, this limitation is far less important in most applications than the effective damping of eddy currents in SMCs.

[0084] The properties desired according to the invention, dynamics and efficiency, cannot be sufficiently achieved with the known soft magnetic alloys (as solid materials).

[0085] Another essential aspect of the invention is the strain relief of the drive coil(s) and / or the frame, since the properties desired according to the invention can only be achieved at very high magnetic pressures, which leads to a strong structural stress on the drive during each positioning operation.

[0086] For strain relief of the frame (10), in addition to enclosures (20) made of, for example, so-called maraging steels, fiber composite materials are particularly suitable. For strain relief of the coil (30), it is possible to wind and pot high-strength fibers or textiles with or around the electrical conductor(s) of the coil. In this case, the fiber material is preferably selected not only for its tensile strength but also for having a higher tensile modulus than the electrical conductor itself. Finally, the coil can be potted or overmolded, with the potting compound preferably being selected to have, on the one hand, the highest possible inherent strength, a high yield strength, and a high tensile modulus (for a polymer), and on the other hand, to adhere as firmly as possible to the electrical conductor or its coating surface as well as to the fiber material itself.If the drive is operated under conditions that lead to a significant thermal load on the coil, the potting compound should also be selected to have high thermal conductivity; for this purpose, the potting compound itself can be filled accordingly, for example with AIN as a filler.

[0087] If necessary, the coil can also be equipped with a cooling device, in particular active or passive liquid cooling, and / or a fixed thermal connection of the coil to the soft magnetic frame can be provided, which in turn can itself be thermally connected to a heat sink.

[0088] Finally, the invention will be explained using a specific example. Fig. 1 and 2Figure 1 shows longitudinal sections of a first and a second embodiment of the drive rotationally symmetrical about the axis (1) with a soft magnetic frame (10), similar in shape to the frame of known pot magnets, with a rounded lower edge, a strain-relieving housing made of maraging steel (20), a first excitation coil (30) directly or indirectly supported against the frame (10), which is formed from, for example, fiber-reinforced flat wire and is potted, wherein, to control the skin effect, each individual turn can be formed like a stranded wire from several thin (flat) wires connected in parallel, and the squirrel-cage rotor (40), which consists of a high-strength (hardenable) aluminum alloy (e.g., 7068), and in which an electrically highly conductive ring (41) made of (here, for example, pure Cu) is embedded on the side facing the coil.

[0089] Alternatively, it is possible to connect a ring (41) (made of Cu or Al or a Cu or Al alloy with significantly increased strength compared to the pure metals, but with the best possible electrical conductivity), which, for example, has the same outer and inner radius as the rest of the squirrel-cage rotor (40), to the side of the first excitation coil (30) by means of a material-locking or form-locking connection with the (40).

[0090] Compliance with all strength requirements in the design of a specific drive for the application should preferably be determined with the aid of computer simulations (FEM).

[0091] In Fig. 1 A housing (20) in the form of a cylindrical shell is used as strain relief, which surrounds the circumference of the frame (10) over its entire axial length. Fig. 2 In contrast, the enclosure (20) has a bottom area in addition to the cylindrical shell.

[0092] The squirrel-cage rotor has a sliding bearing (42) on its outer circumference, by which the rotor is axially displaceable within a housing (50) of the drive. The rotor (40) is connected to an axially extending piston (45), which serves to transmit the forces generated by the rotor. The piston extends from the rotor through the interior of the housing and through a piston guide (49). Preferably, the piston (45) is also slidably mounted.

[0093] Preferably, a device or design is used which reliably prevents the squirrel-cage rotor (40) from (permanently) contacting the first excitation coil (30) when the drive is reset, thus avoiding possible damage to the coil.

[0094] The housing can serve as shielding for the drive unit to meet the relevant EMC criteria. Therefore, the housing is preferably made of aluminum and / or an aluminum alloy.

[0095] In particular, age-hardenable aluminium alloys such as 7068 can be used in an age-hardened state, as they combine high electrical conductivity with high mechanical strength and sufficient corrosion resistance.

[0096] Furthermore, the drive can be shielded by an outer enclosure – preferably thin – made of highly permeable soft magnetic material (e.g., micro-metal), which should also exhibit high saturation polarization. Here, films made of soft magnetic metallic glasses or nanocrystalline materials with saturation flux densities >1 T (and va >1.2 T) are particularly suitable, being significantly superior to micro-metal.

[0097] In Fig. 1For this purpose, a surface (43) of the piston (10) or the squirrel-cage rotor (40) facing the frame (10) is designed as a stop, which defines the position of the squirrel-cage rotor in the initial stroke position. The stop (43) can interact with the frame (10).

[0098] Preferably, the stop (43) interacts with an adjustment element by which the distance between the bottom end of the squirrel-cage rotor (40) or the ring (41) in the initial stroke position and the excitation coil (30) can be adjusted. For example, a screw can be passed through the bore 14 in the frame (10) and serve as an adjustable counter-stop. This prevents the bottom end of the squirrel-cage rotor (40) or the ring (41) from damaging the excitation coil (30) when it is returned to the initial stroke position.

[0099] Fig. 3Figure 1 shows that the frame (10) can be composed of a plurality of parts (circular segments in the outer area of ​​the frame); this allows a certain degree of movement between the parts during operation, thus preventing damage to the comparatively brittle SMC. The frame parts are preferably also potted or bonded together, with the potting compound or adhesive preferably being a chemically compatible, well-adhering, strong elastomer with a high yield strength.

[0100] The schematic in Fig. 1The electrical leads (52) to the first excitation coil (30) shown should be arranged so that these unavoidable leads impair the usable magnetic cross-section of the frame as little as possible. For operation of the drive, a capacitor or a capacitor bank (58) can be discharged via the excitation coil (30) by means of a switch (56), in particular a thyristor. Furthermore, a freewheeling diode is provided between the terminals 59 of the capacitor or capacitor bank. This can be omitted if necessary, especially if film capacitors are used.

[0101] A control unit (55) controls the switch (56) and also takes over the charging of the capacitor or capacitor bank via a switching converter (54).

[0102] The switch (56) is preferably a semiconductor switch, in particular a thyristor.

[0103] To meet the weight requirements, the switching converter must also meet the highest standards. This converter preferably features a semiconductor switch, in particular a large bandgap semiconductor switch (e.g., SiC MOSFETs) and a high-quality core material (especially cores made of soft magnetic metallic glasses and / or nanocrystalline alloys with a discrete air gap).

[0104] Since the already low self-inductance of the coil, given the typically very small number of turns, is further short-circuited by the squirrel-cage rotor, the initial inductance of the arrangement is extremely low, which is what makes the enormous dynamic range possible in the first place. To protect the thyristor from an excessively high current rise rate dl / dt, it may be advisable to introduce a saturating inductance (so-called "saturable reactor"), for example, by routing a supply line to the drive through a saturating, highly permeable toroidal (band) core ("magnetic switch protection"). Otherwise, the impedances of all components must be taken into account when designing the external circuitry of the drive according to the invention.The number of turns of the excitation coil must be matched to both the impedance of the voltage source and the mechanical load, the mechanical load being formed, for example, by the mass of the squirrel-cage rotor and any associated components such as the piston. The electrical efficiency of a drive according to the invention, given a constant capacitance and number of turns, reaches a maximum at a specific mass to be accelerated and a corresponding mechanical load. The drive geometry disclosed in the figures is suitable in many cases for directly designing a highly dynamic drive for a given application without requiring any optimization. Overall, the drive operates by first having the excitation coil (30) repel the squirrel-cage rotor (40), with the associated "force constants" decreasing rapidly with increasing distance.The repulsive Lorentz force is greater for a given signal the smaller the distance between the excitation coil (30) and the squirrel-cage rotor (40). Accordingly, in the initial stroke position, the excitation coil (30) and the squirrel-cage rotor (40) should be positioned as close to each other as possible.

[0105] If electrolytic capacitors (ELKOS) are used, their relatively high internal resistance can lead to significant heating during the adjustment process. To remedy this, the ELKOS can be switched off during the adjustment process. This is preferably achieved by blocking the semiconductor switch or by using a freewheeling mechanism, particularly in the form of a freewheeling diode.

[0106] The ohmic / real internal resistance of the electrolytic capacitor (ELKO) corresponds approximately to that of the coil. It is preferred that the discharge of the ELKO be interrupted after reaching the current maximum, while the ELKO is still partially charged and a large portion of the electrostatic energy from the ELKO has been converted into magnetic field energy in the drive section.

[0107] The current coupled to the magnetic field can then flow through a freewheeling diode with the lowest possible impedance, or another low-resistance freewheeling device, which preferably has a lower effective loss resistance than the electrolytic capacitor itself. In this way, magnetic field energy is not unnecessarily converted into heat within the electrolytic capacitor, for example, in its electrolyte.

[0108] Conventional thyristors cannot be directly switched off. Alternatively, GTOs, IGBTs, IGCTs, and MCTs can be used, which can be switched off, but these are also comparatively expensive. However, it is possible to briefly reverse the current direction in the thyristor (SCR1) using a relatively small second thyristor ("auxiliary valve") and a (small) inductor, while simultaneously switching off or reversing the current to the gate of SCR1.

[0109] However, film capacitors and / or foil capacitors are preferred, as they do not require such a shutdown due to their low internal resistance.

[0110] While film capacitors still have a lower energy density than electrolytic capacitors, they can exhibit an exceptionally low series resistance (ESR). This low series resistance can significantly increase efficiency.

[0111] Another advantage of film capacitors is their bipolarity. They can withstand polarity reversal, potentially eliminating the need for a freewheeling diode, which is particularly helpful in handheld devices due to the associated weight savings.

[0112] A combination of electrolytic capacitors and film / electrolytic capacitors connected in parallel is also possible.

[0113] For film capacitors, a trade-off must be made: energy density versus ESR. The optimum (weight / efficiency - depending on the application) must be determined numerically.

[0114] The drive further comprises a device (80) for resetting the piston (45) and / or the squirrel-cage rotor (40), which is located in Fig. 1 is represented only abstractly as boxes, and now based on Figs. 4a to 4d This will be explained again using an example. Fig. 4c) and 4d ) show the reset device in a sectional view along the axis of movement of the drive in the two end positions.

[0115] The piston return can be achieved, for example, by means of a soft magnetic element (120) extending spatially along the direction of movement of the piston by at least one stroke length, which is preferably rod-shaped, for example, a rod-shaped laminated core or a slotted soft magnetic rod. The soft magnetic element (120) is connected to the piston, preferably rigidly connected, and / or forms the rear end of the piston. The soft magnetic element preferably extends through an axial opening (14) through the frame and is, for example, arranged behind the bottom surface of the drive.

[0116] Matching the soft magnetic element, there exists an arrangement (100) of permanent magnets (PM) which form a magnetic circuit which is increasingly closed when the piston is reset, as the soft magnetic element (120) increasingly moves into the arrangement.

[0117] The flux of the permanent magnets is guided into the soft magnetic part entirely or predominantly perpendicular to the direction of movement. The permanent magnets can be designed in the manner of a so-called Halbach array to eliminate the otherwise necessary "iron back-end" and thus save weight, while still allowing for a minimal stray field.

[0118] In Fig. 4a) and 4b Figure 1 shows two different configurations of such arrangements, with the arrows indicating the direction of polarization of the permanent magnetic elements and / or areas. Both are arrangements in the form of a Halbach array.

[0119] For example, with a Halbach array, in particular according to Fig. 4bIt is possible to guide the flux generated by the PM largely transversely through the movable soft magnetic element (120): Along the direction of movement in a horizontally operated drive, the "field lines" thus enter the "iron" from below and exit from the "iron" at the top. Lateral movements of the iron (along the field lines, i.e., orthogonal to the direction of movement) then lead only to a negligible change in the magnetic field energy, which is why such an arrangement is almost completely free of magnetic transverse forces that could otherwise, for example, load bearings, such as a sliding bearing guiding the soft magnetic element.

[0120] Within the arrangement of permanent magnets, a sliding bearing (110) is provided for the soft magnetic element. The arrangement of permanent magnets preferably surrounds the soft magnetic element and / or the sliding bearing in a ring-like shape and / or has the form of a hollow cylinder.

[0121] Fig. 5 The following shows an embodiment of a nail-setting device according to the invention with a drive such as that described in Fig. 1 and / or 4 is described in more detail. With regard to the electrodynamic drive, we therefore refer to the above description.

[0122] The hand-held nail setting device comprises, in addition to the components of the drive, i.e. the first excitation coil (30), the soft magnetic frame (10), the squirrel-cage rotor (40) movable along the axis (1) and the strain relief (20), at least one capacitor (58), at least one electrochemical energy storage device (53), in particular in the form of an accumulator, a switching converter (54), a switch (56), a piston (45), and a reset device (80) for the squirrel-cage rotor (40) and the piston (45), which is also shown only schematically here.To set a nail (70), the capacitor (58) is first charged with electrical energy from the electrochemical energy storage device (53) using the switching converter (54), whereupon the switch (56) is closed to cause a discharge of the capacitor (58) via the excitation coil (30), whereupon the squirrel rotor (40) and the piston (45) are accelerated from their initial stroke positions, and the piston (45) is used to drive in the nail (70), and after which the return device (80) is used to return the piston (45) and the squirrel rotor (40) to their initial stroke positions.

[0123] The nail is driven in by striking the tip of the piston (45) against a nail 70, which is provided, for example, in a magazine (68) arranged at the front of the nail-setting device.

[0124] The nail-setting process is triggered by actuating the trigger switch (52), e.g., by pressing a button (63). However, the control unit (55) only allows a nail-setting process to be triggered if the tip of the nail-setting device is in contact with the nail, which is detected by the pressure switch (66). The control unit (55) monitors the pressure switch (66) and the trigger switch (52) and controls the switching transducer (54) and the switching transducer (56).

[0125] The nail-setting device (60) further comprises a damper (65) which is suitable for absorbing the kinetic energy of the piston and, if necessary, preventing damage to the device even if the nail can be set without significant effort. The damper is located at the outlet of the housing (50) of the drive unit.

[0126] The housing (61) of the nail setting device surrounds not only the drive but also the capacitors (58), which in this case are arranged axially behind the drive in the housing.

[0127] The housing can serve as the outer casing for the capacitors, thus eliminating the need for their own enclosure. In the area of ​​the capacitors (58), the housing is preferably made of metal to ensure high thermal conductivity and thus good cooling of the capacitors.

[0128] The housing of the nail-setting device comprises a handle area (62) on which the button (63) is arranged. The electrochemical energy storage device (53), in particular in the form of a battery, is preferably arranged in a separate housing part 64, which can be detachably connected to the rest of the housing in order to be able to replace the electrochemical energy storage device.

Claims

1. Nail setting device, comprising an electrodynamic drive, in particular a highly dynamic electrodynamic drive, in particular constructed in the manner of a Thomson coil with soft-magnetic frame, wherein the electrodynamic drive comprises: - a first excitation coil (30), and - a short-circuit rotor (40) mounted movably along an axis, characterized in that the electrodynamic drive comprises a soft-magnetic frame (10), wherein the frame (10) has a saturation flux density of at least 1.0 T and / or an effective specific electrical conductivity of not more than 106 S / m.

2. Nail setting device according to claim 1, wherein the first excitation coil (30) and / or the frame (10) include at least one means for strain relief, and / or wherein the excitation coil (30) has a winding height which is greater than its length, which hence is flat, and / or wherein the excitation coil (30) is arranged in the soft-magnetic frame (10) and abuts against the same.

3. Nail setting device according to any one of the preceding claims, wherein the frame represents an open magnetic circuit which includes an outer region (11), a bottom (12) and an inner region (13), and which has an end-face opening, wherein the first excitation coil at least partly encloses the inner part (13) of the frame, and wherein the short-circuit rotor (40) in its stroke starting position dips into the end-face opening of the frame (10) and thereby at least partly encloses the inner part of the frame (13), wherein the short-circuit rotor is preferably formed to be hollow-cylindrical at least on its side facing the first excitation coil (30) and / or wherein the frame is preferably constructed in the manner of a pot magnet.

4. Nail setting device according to any one of the preceding claims, wherein the soft-magnetic frame entirely or predominantly is formed of a soft-magnetic composite material and / or one or more sheet stacks.

5. Nail setting device according to any one of the preceding claims, characterized in that the short-circuit rotor (40) dips into a space between the outer (11) and inner (13) region of the frame which has the shape of cylinder jacket, wherein its longitudinal axis corresponds to a direction of movement of the drive and / or a winding axis of the coil(s).

6. Nail setting device according to any one of the preceding claims, characterized in that the short-circuit rotor (40) of the drive wholly or partly is formed of a nonmagnetic material, preferably of a curable aluminum alloy, and / or wherein the short-circuit rotor on the bottom side, i.e. in the stroke starting position, has a ring of electrically well-conducting material, for example copper, on the side of the short-circuit rotor (40) facing the first excitation coil (30), wherein the ring preferably is embedded into the short-circuit rotor and in particular into the nonmagnetic material and / or is cohesively and / or positively connected with the short-circuit rotor.

7. Nail setting device according to any one of the preceding claims, characterized in that the electrodynamic drive at least partly is operated by means of a capacitor discharge.

8. Nail setting device according to claim 7, characterized in that the capacitor discharge is accomplished by switching one or more semiconductor switches, wherein the semiconductor switch preferably is a thyristor.

9. Nail setting device according to any one of the preceding claims, characterized in that at least the major part of the frame (10) has an effective specific electrical conductivity of less than 105 S / m, preferably of less than 104 S / m.

10. Nail setting device according to any one of the preceding claims, characterized in that the material of the frame (10) entirely or predominantly has a saturation flux density > 1.5 T, preferably of > 1.75 T, more preferably of > 1.9 T.

11. Nail setting device according to any one of the preceding claims, characterized in that the first excitation coil (30) has a copper filling degree of at least 30%, preferably of at least 40%, more preferably of at least 50%, even more preferably of at least 60%.

12. Hand-held nail setting device according to any one of the preceding claims, further comprising: - at least one capacitor, - at least one electrochemical energy storage device, - at least one switching converter, - at least one switch, - a piston, - a resetting device for the short-circuit rotor and the piston, wherein for setting a nail, first the capacitor is charged with electric energy from the electrochemical energy storage device by means of the switching converter, whereupon the switch is closed in order to accomplish a discharge of the capacitor via the excitation coil, whereupon the short-circuit rotor and the piston are accelerated out of their stroke starting positions, and the piston is used to drive-in the nail, and whereafter the resetting device is used to return the piston and the short-circuit rotor into the stroke starting positions.

13. Hand-held nail setting device according to claim 12, characterized in that it is formed such or otherwise includes such an additional device that when resetting the drive, i.e. when returning the short-circuit rotor (40) and the piston into their respective stroke starting position, a mechanical contact between short-circuit rotor (40) and first excitation coil (30) is prevented, wherein preferably an adjustable stop is provided for the short-circuit rotor (40) and / or the piston, in particular in the form of a screw going through the frame.

14. Hand-held nail setting device according to any one of claims 12 or 13, characterized in that the setting energy, in particular the setting energy achievable by charging the one or more capacitors is ≥ 10 J, preferably ≥ 100 J, preferably ≥ 200 J.

15. Hand-held nail setting device according to any one of claims 12 to 14, characterized in that it includes an electrolytic capacitor or a film capacitor or a foil capacitor, wherein its housing preferably is at least partly formed by the housing of the setting device itself, the reel of the capacitor hence does not have a complete housing of its own.