Patent Grant
10181373
The present application is a U.S. National Phase of International Patent Application Serial No. PCT/DE2014/100374, entitled “Electromechanical Actuator,” filed on Oct. 19, 2014, which claims priority to German Patent Application No. 10 2014 013 723.6, filed on Sep. 22, 2014, and German Patent Application No. 10 2014 007 771.3, filed Jun. 1, 2014, and German Patent Application No. 10 2014 004 888.8, filed Apr. 5, 2014, and German Patent Application No. 10 2013 017 508.9, filed Oct. 23, 2013, the entire contents of each of which are hereby incorporated by reference in their entirety for all purposes.
The present invention relates to the field of electromagnetic actuators, for example to a reversing linear solenoid.
Reversing linear solenoids are generally known and form the prior art. For example, bistable designs are used for driving electrical medium-voltage switching devices, with electrolytic capacitors being needed for the power supply of the magnets. Further fields of use can be found, for example, in solenoid valves which should be able to maintain a state against a returning force without any control current. In addition, there is a high number of further applications, inter alia in sorting and conveying plants, but also in the automotive sector (in particular transmission engineering, central locking systems, shift locks) as well as in knitting machines. Important possible areas of use are also present in the field of so-called hot-runner engineering (actuating the needles of injection molding tools) and in the field of robot welding tongs (tracking the welding electrode, with the required clearance compensation being able to be ensured by springs).
A disadvantage of known reversing linear solenoids, which frequently precludes their use instead of pneumatic or hydraulic drives (or spring accumulators locked by force transmission), is their frequently small electrical efficiency. This results in substantial costs in medium-voltage switching devices using (bistable) reversing linear solenoids, primarily due to the expensive electrolytic capacitors. In other fields of the art, in particular with valves in engines—for example gas valves in large gas engines—the small electrical efficiency results in an unwanted limitation of the permitted frequency or occurrence of switching by the power loss occurring in the coils (the coils would be thermally destroyed at higher switching frequencies).
A further disadvantage of known reversing linear solenoids is their small dynamics since, in particular with comparatively long-stroke drives (long-stroke in comparison with the magnet diameter), only a small initial force is frequently available and, in addition, comparatively large tolerances are unavoidable. For instance, power switches should disconnect short-circuits from the mains as fast as possible in switching off or should impact the zero crossing of the current or that of the voltage on switching on; high dynamics with short dead times are required for this purpose—this is only insufficiently possible using conventional reversing linear solenoids.
Finally, a disadvantage of known bistable reversing linear solenoids can be seen in the fact that they tend to show the highest armature speed when the armature reaches an end stroke position at the end of an adjustment procedure. This results in a high effort for the end position damping or restricts the service life of the magnet.
In some applications, above all in valves and electrical switching devices, reversing linear solenoids should be monostable instead of bistable optionally to be able to adopt a safe end position without any control current.
It is therefore the underlying object of the invention to increase the electrical efficiency of polarized reversing linear solenoids, in particular of polarized bistable reversing linear solenoids. The new magnets should furthermore be able to have dynamics which are high in comparison with known reversing linear solenoids with reduced dead times. In addition, a common demand on actuators is a compact construction.
The named object is achieved by a drive in accordance with one of the independent claims. Various embodiments, further developments and applications are the subject of the dependent claims.
In accordance with an example of the invention, the reversing linear solenoid with permanent magnetic polarization has a spring system which exerts a force on the armature in both end stroke positions, the force being directed in the direction of movement toward the center stroke position (i.e. toward the center between the two end stroke positions). In this respect, the spring system is to be designed such that the spring force in at least one end stroke position is smaller in magnitude than the total reluctance force acting on the armature in the static, non-energized case so that the armature can be kept stable in a permanent magnetic manner against the spring force in at least one end position.
Not only spring systems having mechanical springs can be considered, but also magnetic or pneumatic spring systems. What is decisive is that a force acting in the direction of the center stroke position disposed between both end stroke positions can be transmitted to the armature or to the armature system in both end stroke positions. The spring system is to be configured for bistable magnets such that the potential energy stored in the spring system is, where possible, the same in both end stroke positions. The spring force must be smaller in magnitude in both end stroke positions than the associated reluctance force in the static, non-energized case. If the application to be provided by the reversing linear solenoid itself produces a returning force, this must be taken into account accordingly in the design of the spring system. This is the case, for example, with vacuum power switches whose contact pressure springs are to be understood as part of the spring system here.
The drives in accordance with the invention should be able to be configured such that they can produce greater forces with respect to their volumes (than know reversing linear solenoids). Ultimately, the drive should also be able to be designed as monostable and should nevertheless be able to have short adjustment times and high efficiencies.
The invention will be explained in more detail in the following with reference to examples shown in the Figures. The illustrations are not necessarily to scale and the invention is not only restricted to the aspects shown. It is rather important to show the principles underlying the invention.
The invention will first be explained in the following for the example of bistable reversing linear solenoids. As a result of the spring system, the armature is set into movement from every end stroke position in the direction of the center stroke position as soon as the retaining force (the retaining force is defined as the total reluctance force on the armature in the respective end stroke position) becomes smaller in magnitude than the spring force as the result of an electrical counter-excitation. For this purpose, a much smaller electrical power is required than with conventional bistable reversing linear solenoids without a spring system; the associated (external) force slew rate can also be much higher. For example, it also approximately applies in the start stroke position in a conventional bistable reversing linear solenoid:
Fext=(FGap1+FGap2)−FAbutment=1/(2*μ0)*(A1*BGap1^2+A2*BGap2^2)−FAbutment
where A1 and A2 are the (opposite) pole surfaces of the armature and FAbutment is a function mapping the end position abutments.
Let it be assumed for illustration that the air gap Gap2 is closed except for a residual air gap and this residual air gap conducts a flow having a density of 2T (BGap2=2T), while air gap Gap1 is completely open and does not conduct any flow ((BGap1=0T). So that the sum of the opposite reluctance forces FGap1+FGap2 acting on the armature changes sign along the axial direction of movement of the armature, the flux density in Gap1 has to be larger than the flux density in Gap2 under the condition A1=A2. A large electrical power can be required for this purpose since Gap1 is fully open. In the simplest approximation, the current required for generating a given flux density in the air gap is proportional to the air gap length; however, the associated power loss is the square of the current.
It can be assumed for very small strokes, while neglecting the stray field and eddy currents (static or quasi-static case), that the flux density stroke generated by the counter-excitation in both air gaps Gap1 and Gap2 is of the same magnitude. In this case, which is most favorable for conventional bistable reversing linear solenoids, a flux density stroke would be necessary in the present example of 1T in each case (Gap1: 0T→1T, Gap2: 2T→1T) in order only to compensate the retaining force completely.
Let the same magnet now be equipped with a spring system in accordance with the invention which, in the previously described start stroke position (position “0”) exerts a force FSpring (0) in the direction of the center stroke position which can be said to be half as much as the (retention) force. A reduction of the flux in Gap2 from 2T to (sqrt(2))T is thus sufficient to allow the reluctance force acting on the armature via Gap2 to become of equal magnitude with the spring force. The reluctance force acting on the armature via Gap1 is thus already available for accelerating the armature; and indeed with a flux density stroke (at Gap2) of only −0.59T. If, as in the preceding example, the flux density in Gap2 is reduced as a result of electrical counter-excitation from 2T to 1T and if it is increased in Gap1 from 0T to 1T, half of the spring force (Fspring−FGap2 at BGap2=1T is actually available for accelerating the armature in the start stroke position 0 plus a reluctance force FGap1 which produces a quarter of that force at 1T which would be produced at T2. Under the same assumption of A1=A2, this is a force of approximately the same magnitude as the force produced by the spring. The drive can thus produce a force at a flux density stroke of 1T (+1T in Gap1, −1T in Gap2) directly in the start stroke position despite a fully open working air gap Gap1, which force corresponds to approximately half the retaining force, corresponding to the spring force used. It can already be seen in this rough approximation to a particularly favorable case for conventional bistable reversing linear solenoids that drives in accordance with the invention require a much smaller electrical power to be set into movement—with the drive advantageously being configured such that the larger part of the energy initially accelerating the armature is taken from the spring system and is not electrically expended, for instance. It can further be seen that the armature movement can already be made possible at much smaller flux density strokes, in comparison with conventional magnets, which in turn allows short dead times (naturally at the cost of the effective retaining force which results from the sum of the spring forces and reluctance forces).
It is important for the understanding of the invention that the armature can first be accelerated primarily with spring force, for which purpose a comparatively small electrical power take-up is required (for counter-excitation). Moving or accelerated electrical machines can have much higher electrical efficiencies than those which start from an idle state. This is ultimately due to the fact that the work carried out by the drive is an integral of the force over the adjustment path, but the heat loss is an integral of the power loss over time. It is thus clear that a cut in the adjustment time, that is a reduction in the integration interval in the time domain, will tend to result in an increase of the electrical efficiency. It is equally clear that a “seizing” of the armature in any position has to produce an efficiency of zero since the work integral disappears and the integration time escalates.
It is therefore an aspect of the example in accordance with the invention described here that only a small counter-excitation which can be produced quickly is required for triggering the movement. A further aspect comprises the fact that a symmetrical spring system could move the armature to and fro between its end positions within a specific period in the absence of magnetic fields and in the absence of friction, without any energy having to be used for this purpose. The spring system has to be designed for this purpose such that the (potential) energy elastically stored therein is, where possible, of equal magnitude, in both end stroke positions. With a spring system designed in this manner, only the above-named counter-excitation has to be produced and only so much electrical power has to be supplied to the drive that it can be set in motion, can overcome the friction and such that, optionally, useful work can additionally be carried out. In contrast to this, with the conventional bistable reversing linear solenoids, a much larger counter-excitation first has to be produced, which is associated with corresponding ohmic losses. The armature then has to be accelerated only with the aid of electrical power, which takes place comparatively slowly and is therefore likewise energy-intensive. The magnet must also overcome friction and carry out useful work, but actually with an in turn low efficiency, inter alia due to the long adjustment times due to the typically small force and force slew rate at the stroke start. The conventional bistable reversing linear solenoid usually reaches its highest armature speed when the armature impacts the stroke end. In this respect, the kinetic energy communicated to the armature is converted into heat, sound and, unavoidably also into the plastic deformation of drive components. This high kinetic energy as a result of the high speed on the impact into the end stroke position is, on the one hand, wasted for the purpose of the drive, where applicable, and it otherwise threatens its service life through strong wear and, where required, makes a complex and expensive end position damping necessary. In contrast to this, with drives in accordance with the invention, the kinetic energy of the armature (and optionally of further parts, e.g. at the application side, mechanically associated therewith) is in turn largely stored in the spring system (“recuperated”) and is thus available for a following adjustment procedure in the opposite direction (apart from (friction) losses).
In summary, drives in accordance with the invention as a rule have to carry out less work than conventional reversing linear solenoids in order to be able to move from one end stroke position into the other in finite time. And as a result of the “pre-acceleration” by the spring system, they can also carry out this smaller required work at a higher electrical efficiency. This results in correspondingly small power losses and allows higher switching frequencies, where they have up to now been limited by the loss power or (integral) heat loss.
With small strokes, that is when the working air gaps can be assumed in a good approximation as “small” or “short”, the drives forming the subject of the invention have large advantages over conventional bistable reversing linear solenoids. The dead time of the drives described here is as a rule smaller; the adjustment time is smaller; the efficiency is higher; the end position speed is in turn smaller. The innovative magnets in a bistable design admittedly have at least one snap-in point which does not correspond to any end stroke position as a result of the spring system in the non-energized case. The magnets can, however, easily be designed such that the armature is nevertheless magnetically conveyed into the sought end stroke position against the returning force of the spring system. On operation at a switchable (constant) voltage source, the magnet can be configured such that it does not nearly reach its equilibrium current as a result of counter-induction from the coil or coils on a regular adjustment process. If now, as a result of the behavior of the mechanical load, for example a high friction, the drive is “captured” in the environment of its snap-in point, the current increases and thus, with a certain delay due to self-induction and eddy current effects, the reluctance force which acts on the armature and can ultimately always be sufficient to tension the spring system again and to convey the armature into the sought end position.
With long-stroke drives (i.e. the stroke in the longitudinal direction is longer than the width of the air gap in the transverse direction) in which the above approximation of the “small air gap” is not satisfied, a snapping-in in the spring system is in contrast more easily possible. A remediable weakness of the long-stroke design of the drive can also be seen here: The highest armature speed can be reached, in dependence on the design of the spring system and on the load behavior, in the region of the center stroke position, that is when the working air gaps of the simple armature are wide open. Wide-open air gaps, however, produce low “force constants” (actually force functions), i.e. a given current only produces a small reluctance force. This contradicts the above-described purpose—just where the highest armatures speeds can be achieved with an additional drive by the spring force, where consequently a high electrical efficiency can theoretically be mapped, the “force constants” at the drive in accordance with the invention are small without characteristic influence, which can impair the advantage of the invention.
Drives in accordance with the invention are therefore advantageously to be equipped with a means for characteristic influencing if their strokes are so large that the associated working air gaps cannot be approximated as “small” in every regular operating state. If this means is a geometrical characteristic influencing, it has to be matched to the spring system in accordance with the invention. The characteristic influencing can also reduce the series reluctance of the working air gaps and thus help to minimize the required trigger power.
A further disadvantage of conventional bistable reversing linear solenoids can be seen in the fact that they have an external flux guidance. The flux produced in a permanent magnetic manner has to be fed into the armature, on the one hand, and has to be supplied about at least one coil to the pole surfaces (generally the front surfaces) of the armature. This results in a in increased drive cross-section.
If the drive in accordance with the invention should have a particularly compact construction shape, it comprises two or more frame parts of a soft magnetic material between which a magnetic tension is generated in a permanent magnetic manner. The drive furthermore comprises at least two soft-magnetic armature parts (armature plates in the following), namely the first and second armature plates, which are rigidly connected to one another. In accordance with the invention, the drive has two end stroke positions, namely a first and a second end stroke position. The drive is configured such that, in a first end stroke position, the first armature plate magnetically short-circuits the frame parts, except for unavoidable residual air gaps, whereas the working air gaps at the second armature plate are open to a maximum. In a second end stroke position, the second armature plate correspondingly magnetically short-circuits the frame parts and the working air gaps at the first armature plate are open to a maximum. A compulsory displacement of the armature parts (armature plates here) rigidly connected to one another from the first end stroke position into the second accordingly has the result that the flux produced in a permanent magnetic manner primarily commutates from the first to the second armature plate. (The working air gaps of both armature plates (toward the frame) are connected magnetically in series with one another with respect to the magnetic flux produced with the aid of the drive coil(s). The named working air gaps of the two armature plates are connected magnetically in parallel with respect to the flux produced in a permanent magnetic manner).
The armature 10 and the frame are formed in contrast as an armature/armature counterpiece system which greatly increases the degree of utilization of the magnets on attracting the armature 10. The armature/armature counterpiece system of armature 10 and the frame parts 30, 31, 32 comprises the working air gaps δ10, δ12, δ13, δ14 which occur doubled due to the mirror symmetry of the drive, but are termed in the singular. The same applies to the radial air gaps δ11 and δ15 which are likewise parts of the geometrical characteristic influencing. As can be seen in
It is in particular obvious with rotationally symmetrical drives, but also with parallelepiped drives in accordance with the invention having two armatures to implement the rigid connection between the armatures by a centrally arranged rod which extends, for example, coaxially to the cylinder axis with cylindrical magnets. If this rod connected to the armatures is surrounded by the drive coil or coils, it can advantageously itself comprise soft magnetic material and serve the flux guidance. This additional flux naturally has to be taken into account accordingly in the dimensioning of the pole surfaces.
The schematic representation of
If only a small cross-section is required for carrying out the invention and if the construction length is, if anything, insignificant, two stators polarized in a permanent magnetic manner and one single armature can also be used instead of two armatures and one single stator polarized in a permanent magnetic manner. Such embodiments admittedly require approximately double the amount of permanent magnet materials (per effective pole surface) and are also approximately twice as long in construction than those drives having two armatures. However, with a correct design, they can have particularly high dynamics, at least in short-stroke designs, due to the smaller armature mass. To further increase the dynamics, in addition to an electrodynamic additional drive (cf. e.g. WO 2011/003547 A1), an increase in the number of pole pairs can also be considered to reduce the armature mass (the “armature plate” can then have a thinner design); in such a case, the frame or frames comprise(s) more than two (rotationally symmetrical construction) or three (“angled” construction) soft-magnetic parts which are set under magnetic tension with respect to one another.
Different soft-magnetic parts are by no means to be understood such that they have to be physically separate from one another. They can also, as described above, be separated from one another by fully or partially saturated regions; what is decisive is solely that the magnetic tension required between these parts or—more precisely—regions can be caused in a permanent magnetic manner.
All the drives in accordance with
A further example of the invention will be explained in the following with reference to a monostable reversing linear solenoid. Monostable embodiments of the invention are obtained in that the reluctance force acting on the armature or on the armature system in the stationary, non-energized case is only larger than the associated spring force in the one end stroke position, but not in the other. The spring and the magnet are coordinated with one another in this respect such that the sum of spring force and reluctance force in the stationary, non-energized case (“stationary total force”) has the same sign at each point of the adjustment path. In the non-energized case, the drive is therefore only stable when the armature (or the armature system) is in its one stable end stroke position. In terms of magnitude, the total stationary force (of magnetic force and spring force) has to be larger than the friction possibly acting on the system; where necessary, the associated stationary total force characteristic has to be coordinated to the respective application with respect to possible restoring forces (for example, the pneumatic pressure when the monostable drive has to overcome a pneumatic valve such as is used in automatic transmissions).
The reluctance force in the stationary, non-energized case may not be limited by magnetic saturation in the unstable end position. This means that in that magnetic part circuit which includes the adhesive surface(s) of the armature contacting the stator, magnetic saturation should by no means and in no region occur across the total effective iron cross-section. In this manner, the reluctance force in the non-energized, unstable end stroke position can be increased so far by energizing the coil(s) that the magnet is also (meta-)stable against the spring force in this (“second”) end stroke position as long as the electrical power required for this purpose is utilized. The magnet here should be dimensioned such that an increase of the reluctance force which is as large as possible in the “unstable” (“second”) end stroke position is reached with as little electrical power as possible—this is also important to be able to maintain the magnet in the unstable end position with high switched-on durations. As regards the spring system, it does not have to be linear. It preferably has a progressive characteristic with respect to the stable end stroke position; that is, the spring force driving the armature system in the direction of the center stroke position increases more than linearly when the armature system approaches the stable (“first”) end stroke position. This can also be achieved by a combination of a plurality of linear springs.
The magnetic principle will be illustrated with reference to
A completely different embodiment (here: a rotationally symmetrical embodiment) of a drive in accordance with the invention is shown in
The permanent magnets can be formed, for example, as diametrically or radially polarized circle segments. A bistable drive can also be obtained with only one of the two magnets installed so-to-say back-to-back, that is with “half a drive”, and indeed in that the other is replaced with a spring or spring system to be dimensioned accordingly. Such drives also do have to be of rotationally symmetrical design. Non-rotationally symmetrical variants can in addition be implemented with a transverse flux guidance to represent drives with a particularly long stroke. It is the advantage of drives in accordance with
It is obvious to design rotationally symmetrical embodiments of the magnet, or at least to design those with a rotationally symmetrical inner pole from SMC materials, for high-dynamic drives in particular having mechanical springs. Parts machined from a solid material in a cutting process are better suited for the slower “spring-less” design (that is one without mechanical or pneumatic springs), above all on a use of the described eddy current brakes. The back iron R, on the one hand, allows an easy assembly of the permanent magnets for which it also serves as an abutment, but equally greatly influences the characteristic and above all increases the force at the stroke start.
The magnetic circuit of a further embodiment of the invention is shown schematically in
In a first embodiment, the present disclosure provides for a drive having a reversing linear solenoid which is polarized in a permanent magnetic manner and which has a first and a second end stroke position, a center stroke position disposed between the end stroke positions and at least one armature, characterized in that the drive has a spring system or is operated at such a spring system which exerts a force in the direction of the center stroke position on the armature or armatures in each of the two end stroke positions, with the spring system and the reversing linear solenoid being coordinated with one another such that the armature or armatures can be held in a permanent magnetic manner against the spring force in both end stroke positions. In a first example of the drive of the first embodiment, the spring system is designed such that the potential energy (elastically) stored therein by movement of the armature or armatures in its/their end stroke positions is of equal magnitude in both end stroke positions while taking account of external returning forces acting from outside on the spring system. In a second example of the drive of the first embodiment, the drive is further characterized in that it has a large (nominal) stroke, that is the length of the fully open working air gaps is not substantially smaller than their smallest extent (“width”) perpendicular to the air gap length; and in that the drive has a (constructional) geometrical characteristic influencing. Further, in the second example of the drive of the first embodiment, the geometrical characteristic influencing is to be dimensioned as so large that the magnetic retaining force in the end stroke positions does not disappear, but rather amounts to at least one third of that retaining force which would reach an otherwise identical bistable reversing linear solenoid without characteristic influencing, wherein the geometrical characteristic influencing is preferably designed such that a reluctance force is generated at zero points of the spring function of the spring system on an energizing of the drive coil(s) in accordance with the design, said reluctance force being at least 50% larger than that with an otherwise identical magnet, also with the same energizing, but without characteristic influencing. In a third example of the drive of the first embodiment, one or both armature parts forms or form an armature/armature counterpiece system with the frame for a geometrical characteristic influencing. In a fourth example of the drive of the first embodiment, the drive has as a means for characteristic influencing, instead of and/or in addition to a geometrical characteristic influencing, permanent magnets, coils or short-circuit windings fastened to the armature or armatures or armature parts. In a fifth example of the drive of the first embodiment, the drive optionally includes the first, second, third, or fourth example of the first embodiment, and is further characterized in that the frame parts are formed by metal sheet packets or SMC. In a sixth example of the drive of the first embodiment, the drive optionally includes the first, second, third, fourth, or fifth example of the first embodiment, and is further characterized in that the armature parts are configured as armature plates which are formed from metal sheet parts or SMC. In a seventh example of the drive of the first embodiment, the drive optionally includes the first, second, third, fourth, fifth, or sixth example of the first embodiment, and is further characterized in that the armature parts are made from solid soft magnetic material into which slits are introduced for damping the eddy currents. In an eighth example of the drive of the first embodiment, the drive includes the seventh example of the first embodiment, and is further characterized in that the armature parts have a specific electrical resistance which is at least twice as high as that of pure ferritic iron. In a ninth example of the drive of the first embodiment, the drive optionally includes the first, second, third, fourth, fifth, sixth, seventh, or eighth example of the first embodiment, and is of rotationally symmetrical design with respect to an axis of rotation and which has a single frame manufactured in a powder injection molding process from a soft magnetic composite material, wherein the frame parts under magnetic tension with respect to one another are formed as a result of magnetic saturation of the one frame. In a tenth example of the drive of the first embodiment, the drive includes the ninth example of the first embodiment, and is further characterized in that it has two armature parts which are rigidly connected to one another by a rod which is guided along the axis of rotation by the approximately rotationally symmetrical frame, with the rod preferably being soft magnetic. In an eleventh example of the drive of the first embodiment, the drive includes the tenth example of the first embodiment, and is further characterized in that the spring system is arranged within the frame, for example having spiral compression springs which surround the rod and which are abutted directly or indirectly at the frame. In a twelfth example of the drive of the first embodiment, the drive optionally includes the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh example of the first embodiment, and further is configured as a bistable rotary magnet, characterized in that it executes a limited rotational movement and has a spring or a spring system, with the spring or the spring system producing a torque which is smaller in magnitude in both end stroke positions than the associated magnetic holding torques of the rotary magnet, and which has the opposite sign in both end stroke positions to the magnetic holding torques. In a thirteenth example of the drive of the first embodiment, the drive includes a latching unit, in particular a machine latch.
In a second embodiment, the present disclosure provides for a drive comprising two or more soft magnetic frame parts or frame regions; one or more permanent magnets which set the two or more frame parts or frame regions under a magnetic tension with respect to one another which has the consequence of a magnetic flux; a first soft magnetic armature part and a second soft magnetic armature part which are rigidly connected to one another, wherein at least one working air gap between the respective armature part and a frame part is associated with each armature part; a first end stroke position in which the first armature part magnetically short-circuits the frame parts, while the working air gap or gaps are open to a maximum at the second armature part; a second end stroke position in which the second armature part magnetically short-circuits the frame parts, while the working air gap or gaps are open to a maximum at the first armature part; at least one field coil for generating a magnetic flux, wherein the drive is constructed such that a (forced) movement of the armature parts, synchronized by their rigid connection, from the first into the second end stroke position has the effect that the flux produced in a permanent magnetic manner largely commutates from the first armature part to the second armature part and vice versa; wherein the field coil(s) is/are arranged such that its/their energizing weakens the flux which is produced in a permanent magnetic manner and which passes through the one armature part and amplifies the flux which passes through the other armature part; and wherein the armature parts are connected magnetically in parallel with respect to the flux produced in a permanent magnetic manner, but are connected magnetically in series with respect to the flux produced by at least one coil. In a first example of the drive of the second embodiment, one or both armature parts forms or form an armature/armature counterpiece system with the frame for a geometrical characteristic influencing. In a second example of the drive of the second embodiment, the drive has as a means for characteristic influencing, instead of and/or in addition to a geometrical characteristic influencing, permanent magnets, coils or short-circuit windings fastened to the armature or armatures or armature parts. In a third example of the drive of the second embodiment, the drive optionally includes the first or second example of the second embodiment, and is further characterized in that the frame parts are formed by metal sheet packets or SMC. In a fourth example of the drive of the second embodiment, the drive optionally includes the first, second, or third example of the second embodiment, and is further characterized in that the armature parts are configured as armature plates which are formed from metal sheet parts or SMC. In a fifth example of the drive of the second embodiment, the drive optionally includes the first, second, third, or fourth example of the second embodiment, and is further characterized in that the armature parts are made from solid soft magnetic material into which slits are introduced for damping the eddy currents. In an sixth example of the drive of the second embodiment, the drive includes the fifth example of the second embodiment, and is further characterized in that the armature parts have a specific electrical resistance which is at least twice as high as that of pure ferritic iron. In a seventh example of the drive of the second embodiment, the drive optionally includes the first, second, third, fourth, fifth, or sixth example of the second embodiment, and is of rotationally symmetrical design with respect to an axis of rotation and which has a single frame manufactured in a powder injection molding process from a soft magnetic composite material, wherein the frame parts under magnetic tension with respect to one another are formed as a result of magnetic saturation of the one frame. In an eighth example of the drive of the second embodiment, the drive includes the seventh example of the second embodiment, and is further characterized in that it has two armature parts which are rigidly connected to one another by a rod which is guided along the axis of rotation by the approximately rotationally symmetrical frame, with the rod preferably being soft magnetic. In a ninth example of the drive of the second embodiment, the drive includes the eighth example of the second embodiment, and is further characterized in that the spring system is arranged within the frame, for example having spiral compression springs which surround the rod and which are abutted directly or indirectly at the frame. In a tenth example of the drive of the second embodiment, the drive optionally includes the first, second, third, fourth, fifth, sixth, seventh, eighth, or ninth example of the second embodiment, and further is configured as a bistable rotary magnet, characterized in that it executes a limited rotational movement and has a spring or a spring system, with the spring or the spring system producing a torque which is smaller in magnitude in both end stroke positions than the associated magnetic holding torques of the rotary magnet, and which has the opposite sign in both end stroke positions to the magnetic holding torques.
In a third embodiment, the present disclosure provides for a low or medium voltage switch, in particular a vacuum power switch, which is driven by the drive of the first embodiment or the second embodiment.
In a fourth embodiment, the present disclosure provides for an injection molding tool which has needle valves which are actuated by the drive of the first embodiment or the second embodiment. In a first example of the injection molding tool of the fourth embodiment, the injection molding tool is characterized in that it moreover has a means for clearance compensation, in particular a spindle drive which is driven by an electric motor and which is able to control the position of the drive in the direction of its drive axis.
In a fifth embodiment, the present disclosure provides for robot welding tongs which have the drive of the first embodiment or the second embodiment, to move one or more welding electrodes, wherein a means for clearance compensation is arranged between the drive and the welding electrode(s), for example a spring with a characteristic which is as shallow as possible.
In a sixth embodiment, the present disclosure provides for a solenoid valve for gases or liquids or bulk material (e.g. flour) which is driven by the drive of the first embodiment or the second embodiment. In a first example of the solenoid valve of the sixth embodiment, the solenoid valve additionally has a monostable electromagnet having a returning spring, said monostable electromagnet releasing the drive when energized, but drops when not energized and blocks the drive in that it displaces it by spring force securely into that end stroke position in which the solenoid valve is closed.
In a seventh embodiment, the present disclosure provides for a drive having a reversing linear solenoid which is polarized in a permanent magnetic manner and which has a first and a second end stroke position, a center stroke position disposed between the end stroke positions and at least one armature, characterized in that the drive has a spring system or is operated at such a spring system which exerts a force in the direction of the center stroke position on the armature or armatures in each of the two end stroke positions, with the spring system exerting a force on the armature or armatures which can displace it or them from both end stroke positions in the direction of the center stroke position, but this force is only larger in magnitude in one of the two end stroke positions than the oppositely acting magnetic retaining force so that the armature or armatures can only be held in a permanent magnetic manner in one of the two end stroke positions. In a first example of the drive of the seventh embodiment, the spring system and the magnet are coordinated with one another such that the sum of the reluctance force and of the spring force in the stationary, non-energized case and of the spring force across the total stroke has the same sign. A second example of the drive of the seventh embodiment optionally includes the first example and is further characterized in that the spring system has a non-linear characteristic, and indeed a progressive characteristic with respect to the non-energized stable end position, such that the spring constant increases continuously or discontinuously on the approaching of the armature or armatures (or of the armature system) to this end position.
In an eighth embodiment, the present disclosure provides for a pneumatic valve, characterized in that it is driven by the drive of the first embodiment or the second embodiment or the seventh embodiment; and in that it has a spring for clearance compensation between the valve part and the drive part.
In a ninth embodiment, the present disclosure provides for a transmission valve having a drive in accordance with the seventh embodiment or having a pneumatic valve in accordance with the eighth embodiment.
All the embodiments of the invention previously shown here were linear drives with a limited stroke. Embodiments are, however, also possible as rotary magnets which have a limited rotational movement. In this case, the term “stroke” refers to a rotational movement over a specific angular range. Drives which achieve extremely short adjustment times and high operation frequencies with a simultaneously high efficiency can easily be drafted using the drive shown schematically in
A drive in accordance with
Some important aspects of the invention are summarized in the following, with this summary not representing any exclusive list. In accordance with the invention, the above-named object is satisfied in that the reversing linear solenoid has a spring system which exerts a force directed toward the center stroke position in the direction of movement on the armature in both end stroke positions. In this respect, the spring system is to be designed such that the spring force in at least one end stroke position is smaller in magnitude than the total reluctance force acting on the armature in the static, non-energized case so that the armature can be kept stable in a permanent magnetic manner against the spring force in at least one end position. For bistable magnets, the spring system is to be designed, where possible, such that the potential energy stored in the spring system is of equal magnitude in both end stroke positions and the spring force is smaller in magnitude in both end stroke positions than the associated reluctance force in the stationary, non-energized case. If the application to be provided by the reversing linear solenoid itself produces a returning force, this must be taken into account accordingly in the design of the spring system.
Drives in accordance with the invention can have means for characteristic influencing if their strokes are so large that the associated working air gaps cannot be approximated as “small” in every regular operating state. Said means have to be matched with the spring system in accordance with the invention. The characteristic influencing in accordance with the invention can also reduce the series reluctance of the working air gaps in the case of geometrical characteristic influencing and can thus help minimize the required trigger powers.
If the drive in accordance with the invention should have a particularly compact construction shape, it comprises two or more frame parts of a soft magnetic material between which a magnetic tension is generated in a permanent magnetic manner. The drive furthermore comprises at least two soft-magnetic armature plates, namely the first and second armature plates, which are rigidly connected to one another. In accordance with the invention, the drive has two end stroke positions, namely a first and a second end stroke position. The drive is configured such that, in a first end stroke position, the first armature plate magnetically short-circuits the frame parts, except for unavoidable residual air gaps, whereas the working air gaps at the second armature plate are open to a maximum. In a second end stroke position, the second armature plate correspondingly magnetically short-circuits the frame parts and the working air gaps at the first armature plate are open to a maximum. A compulsory displacement of the armature plates rigidly connected to one another from the first end stroke position into the second accordingly has the result that the flux produced in a permanent magnetic manner primarily commutates from the first to the second armature plate. (The working air gaps of both armature plates (toward the frame) are connected magnetically in series with one another with respect to the magnetic flux produced with the aid of the drive coil(s). With respect to the flux produced in a permanent magnetic manner, the named working air gaps are connected magnetically in parallel, i.e. the working air gaps of the first armature plate are connected in parallel to those of the second armature plate with respect to the second armature plate).
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 017 508 | Oct 2013 | DE | national |
| 10 2014 004 888 | Apr 2014 | DE | national |
| 10 2014 007 771 | Jun 2014 | DE | national |
| 10 2014 013 723 | Sep 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2014/100374 | 10/19/2014 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2015/058742 | 4/30/2015 | WO | A |
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