EP1876623A1 - Safety position switch - Google Patents

Abstract

The switch has a coil (25) and an anchor (24) which is magnetized and movable by a coil. The switch has a magnetizing element (27) for pre-magnetization of the anchor. The magnetizing element is a permanent magnet or another coil. The pre-magnetizing of the anchor is contrary to a magnetizing of the anchor by the former coil.

Description

The invention relates to a position switch with at least one first coil and at least one armature, wherein the armature by means of the first coil is magnetizable and movable. Furthermore, the invention relates to a position switch, which is designed as a safety switch.

Devices for generating a magnetic force, such as occur in magnetic force drives of switches are used, for example, in conjunction with position switches in the industrial and in the private sector. They are used to secure a hazardous area of a machine or production facility subject to a hazard.

Position switches continue to be used in safety technology, systems engineering, automation technology or building technology. In this environment, for example, doors, flaps or other movable objects that serve access to or access to parts of the machine or the production plant must be secured, that is, in detail, that the respective object is detected in the secured position and optionally with a Locking device is locked in the secured position.

Position switches, in particular safety switches, are used for the secure locking of safety doors in which for plant technical or physical reasons opening the safety door does not lead to immediate shutdown of the hazard, but, for example, due to caster of large drives the risk continues to complete standstill. Such safety doors must be reliably protected against opening.

Locking is provided for locking and unlocking the position switch. The tumbler contains a device for generating a magnetic force. Depending on the design, the magnetic force or a spring force may be provided to perform the locking movement. A position or safety switch with tumbler thus contains mostly magnetic force and spring force generating elements. The spring force or the spring forces counteract the magnetic force, depending on the type of locking either the construction or the reduction of the magnetic force leads to the locking of the tumbler.

Such devices for generating a magnetic force, which are also called magnet systems or magnetic drives, must meet various requirements. In order to overcome the counterforce of the switching element, the highest possible power budget should be available with the largest possible switching path. Here, a high force, especially in the end positions of the anchor must be available. Since the armature usually has two end positions and the coil force increases exponentially when the tumbler is switched on as a function of the movement of the armature, at least one end position of the armature has a small magnetic force. This leads to comparatively small forces at the beginning of the movement, which adversely affect the switching behavior of the tumbler. Furthermore, the smallest possible design of the position or safety switch is desired, as well as a low power consumption.

FIG. 1 shows the graphs G1 and G2, where G1 shows the force of a switching unit as a function of the switching path S. G1 rises with the deflection S of the armature, wherein the armature moves from the rest position to the locking position. As a rule, a number of springs or spring forces are involved in the actuation process of a switching element, so that abrupt changes occur during the counterforce increase. The problem is that the coil force is relatively low, usually zero, just in the vicinity of the rest position of the armature. G2 clearly shows that the coil force starts at the origin of the graph and only after a certain starting path of the armature the counterforce of the switching unit could overcome. In practice, there would be no switching process here, since the balance of power in the origin would be in favor of the opposing force. So far, it has been remedied with a brief overcurrent of the coils contained in the magnetic drive, whereby a short-term increase in magnetic force is generated to overcome the opposing force. This has a negative effect on the life of the magnetic drive.

Out EP 0 977 228 B1 For example, a high power magnetic force drive based on a momentary overcurrent known for use in a position switch is known.

The invention is based on the finding that a high power budget for the magnetic drive means of coils higher power (typically 5 to 8 watts) can be realized, although not only the space requirement, but also the self-heating of the magnetic drive is unnecessarily increased. In addition, such a position switch for direct control by ASI is not suitable because the available current is limited.

The invention is based on the finding that a further alternative magnetic drives with a small footprint, if the switching power or counter-force of the switching unit is low. However, this leads to smaller switching paths, which have a security problem with such locks because of their high tolerance.

The invention has for its object to provide a device for generating a magnetic force, which manages with low power and small footprint, with a high power budget, especially in an end position of the armature, is available.

The object is achieved in a position switch of the type mentioned by at least one means for biasing the armature.

The operation of the device for generating a magnetic force of the claimed position switch is based on means for biasing the armature. The armature is magnetizable by means of a first coil, which is also provided for movement of the armature. This magnetization builds up in the interplay with the permanently counteracting spring force, for example a switching unit. According to the invention, before magnetization of the armature by the first coil occurs, biasing is produced in the armature, which makes the magnetic force, in particular at the first movement points of the armature, larger, possibly significantly greater, than the opposing force. This bias may be permanent or established shortly before magnetization by the first coil. Due to the presence of the bias, a magnetic force is already present before the switching process is set in motion. There is thus an additional magnetic force for the power budget available.

In an advantageous embodiment, the device for generating a magnetic force has a first means for biasing, which is a magnetizing element. Advantageously, this magnetizing element or else a plurality of magnetizing elements can be distributed, for example, in the vicinity of the armature or advantageously in the device for generating a magnetic force. By placing a desired magnetic force can be generated, in particular, a contact between the magnetizing element and the armature or an element of the armature for optimum magnetic flux is advantageous.

In an advantageous embodiment, the magnetizing element is a permanent magnet and / or a second coil. A permanent magnet support for generating a magnetic force is advantageous because the permanent magnet has no power consumption and consequently with a smaller footprint a higher magnetic power budget without short-term overcurrent makes possible. A second coil as a magnetizing element is useful if the height of the magnetic force should be adjustable depending on the position of the armature. It is also conceivable that the bias, which is caused by a second coil, is used for restraint of the armature and counteracts the magnetic force generated by the first coil. At the beginning of the locking operation, the energization of the second coil can be interrupted, so that a necessary force imbalance is generated.

In an advantageous embodiment, the device has a first yoke as a further means for biasing, wherein the armature is pre-magnetizable via the first yoke. An advantage here proves that the first yoke allows flexible positioning of the magnetizing element within the device. In this case, the first yoke directs the magnetic flux from the magnetizing element to the armature. In this context, it is further advantageous that it may come to a contacting of the three elements and thus to maintain a relatively high magnetic flux, whereby the magnetic force can be kept high. Furthermore, can be supported by the shape of the first yoke optimal contacting of the armature or one of its elements with the first yoke. In particular, a flat contacting is advantageous because of an optimal magnetic flux.

In an advantageous embodiment, the magnetic holding force, which is caused by the bias, changes abruptly upon detachment of a holding element of the armature or upon detachment of the armature itself from the first yoke. The abrupt change is achieved by a decontacting of the holding element or the armature from the first yoke, whereby the magnetic flux due to the resulting air gap is substantially reduced.

In an advantageous embodiment, the holding element for guiding magnetic fluxes from the first yoke and a second yoke provided in the anchor. This creates a switching effect when the second yoke is magnetizable from the first coil. In this case, the bias of the armature, which was caused by the first yoke, in a magnetization by the driving first coil in conjunction with the second yoke in an oppositely directed magnetization to. In this case, the armature or the retaining element of the armature changes the contact with the first or second yoke. A position of the holding element or the armature between the first and the second yoke turns out to be energetically unfavorable, which is why a position of this kind is automatically suppressed by a corresponding force difference structure. The retainer or anchor preferably remains in contact with either the first or the second yoke. This ensures a very safe circuit.

Further advantageous embodiments and preferred developments of the invention can be taken from the description of the figures and / or the dependent claims.

In the following the invention will be described and explained in more detail with reference to the embodiments illustrated in the figures.

FIG 1

beispielhafte Magnetkräfte und eine beispielhafte Gegenkraft einer Vorrichtung zur Erzeugung einer Magnetkraft in Abhängigkeit von verschiedenen Ankerpositionen,

FIG 2

schematische Darstellung wichtiger Bestandteile eines ersten Ausführungsbeispiels,

FIG 3

Frontansicht eines zweiten Ausführungsbeispiels eines Positionsschalters ohne Deckel,

FIG 4

geschnittene Frontansicht des zweiten Ausführungsbeispiels aus FIG 3 und

FIG 5

perspektivische Ansicht des zweiten Ausführungsbeispiels aus FIG 3.

Show it:

FIG. 1

exemplary magnetic forces and an exemplary counterforce of a device for generating a magnetic force as a function of different anchor positions,

FIG. 2

schematic representation of important components of a first embodiment,

FIG. 3

Front view of a second embodiment of a position switch without cover,

FIG. 4

cut front view of the second embodiment of FIG 3 and

FIG. 5

Perspective view of the second embodiment of FIG. 3

FIG. 1 shows exemplary magnetic forces G2, G3, G4 and an exemplary opposing force G1 of a device for generating a magnetic force as a function of various armature positions S. As already described in the introduction, G1 represents the schematic course of the opposing force, as represented, for example, by a switching unit of a Position switch, safety switch or contactor is caused dar. This counteracts the magnetic drive and has two sudden increases in the counterforce G1. These are based on a connection of new restoring forces, as they can be caused for example by a variety of springs used. Since a spring force is used as a counter force, there is already a counterforce G1 in the rest position (S = 0). In contrast, a magnetic force G2 opposed to the counterforce G1 normally develops from the origin and increases exponentially with the deflection of the armature. The magnetic force profile of G2 can not be used in conjunction with the counterforce G1, since in the rest position, the counterforce G1 exceeds the magnetic force G2. If this is the case, then no change in position of the armature, that is, for example, a lock or circuit does not take place.

By means of a biasing according to the invention, however, it is possible, as in the magnetic forces G3, G4, at the point S = 0 and at nearby positions to increase the magnetic force substantially compared to the counterforce and thus to avoid a disadvantageous overcurrent. The bias can be opposite to the magnetization by the drive coils or rectified. If the bias is rectified, then the total required magnetization does not have to be generated by the drive coils, so that a lower power consumption or less power coil can be used. If the bias is opposite, a kind of retention effect is created which leaves the armature in position until the bias is canceled by magnetization of the armature by the drive coils. Here, the bias and the associated magnetic attraction of the armature assumes a retention function.

The magnetic force profiles G3, G4 can be regulated by a suitable choice of the magnetizing element, that is, for example, permanent magnets or a second coil. When using a permanent magnet, the behavior of G3 or G4 can not be changed. In a continuous regulation of the magnetic force by means of a second coil and magnetic force courses between G3 and G4 are continuously adjustable.

2 shows a schematic representation of important components of a first embodiment. The first coil 1, also called the drive coil, is provided for magnetization and movement of the armature 4. The armature 4 is in the rest position, wherein it has an air gap 10 to the first yoke 3 out. The first yoke 3 is provided for conducting the magnetic flux which is to be conducted by the magnetic elements 2 in armature 4. The air gap 10, which can be realized for example by a corresponding stop for the armature 4, serves to regulate the magnetic flux from the first yoke 3 to the armature 4. The transmission of the magnetic flux increases almost suddenly with the approach of the armature 4 to a contact surface 3. If the biasing by the magnetizing elements 2 is opposite to the magnetization of the first coil 1, the biasing is capable of fixing the armature 4 in the rest position. Only by activating the first coil 1 is the armature 4 moved in the direction of the center of the first coil 1. There, the armature 4 reaches a switching position, which by a corresponding mechanical, optionally positive connection, can be realized to slide a switching unit.

Advantageously, in the first embodiment, retaining springs which act on the armature 4 are partially or completely eliminated. Their function is taken over by a counterforce, which results from the premagnetization. Advantageously, the magnetic force of the bias changes abruptly with the distance of the armature 4 from the first yoke 3. This creates the desired retention effect.

Advantageously, at least one second yoke 5 is provided, which separates the magnetic flux of the first coil 1 from the magnetic flux of the magnetizing elements 2.

When using the magnetizing elements 2, for example permanent magnets, higher forces are advantageously present at the beginning of the movement. In addition, the return movement of the armature 4 is supported in the rest position by the magnetizing elements 2 when turning off the coil. In this permanent magnet support is to ensure that a mechanical stress of the magnetizing elements 2 during the switching operations remains low. During the movement of the armature 4 out of the rest position, the air gap 10 can be used for mechanical decoupling from the first yoke 3, so that the magnetizing elements 2 are not affected. Conversely, when returning to the rest position, a mechanical stress can be avoided by the first yoke 3 being at least partially semicircular or arcuate, so that the mechanical force flow is not directed to the magnetizing elements 2.

Also in this first embodiment, a return spring for the armature 4 can be designed weak or completely eliminated. Coils with a lower power consumption, so even smaller coils, can be used. This implies a construction space reduction that is a small, narrow design of the position switch allows. The use of the smaller coils entails less heating of the position switch. Alternatively or optionally, it is possible to implement a larger number of poles because of the increased magnetic force at the beginning of the movement of the armature 4. In this case, it has a particularly positive effect that no electronic control for the short-term overload, as was previously necessary, is needed and thus a simple coil structure, which is also more cost-effective, can be used.

3 shows a front view of a second embodiment of a position switch without cover. The position switch is intended for use with a separate actuator (not shown). A component of the tumbler of the position switch is the second locking element 20 which is rotatably mounted in the position switch. The second blocking element 20 is blockable by the plunger 21 in combination with the first blocking element 22, which is designed as a switching wheel and movable by the magnetic drive 34 by means of an actuating plate 23.

Next, the position switch two switching units 28, 32, wherein the left switching unit 28 by means of another actuating plate 30, which is connected on the one hand to the plunger 21 and the left switching unit 28 by means of the foot 31, wherein the foot 31 is formed on the actuating plate 30 , The actuating plate 30 is a flat, angled component, which is provided for the spatial bypass, in particular of the magnetic drive 34.

The right switching unit 32 is positively connected to the armature 24 of the magnetic drive 34. Thus, the left switching unit 28 is provided for detecting the operating state of the position switch, as this is positively triggered by the plunger 21 and by the separate actuator, wherein form-fitting means that due to the shapes of the components, a force path is ensured. In addition, the right switching unit 32 in direct operative connection with the magnetic drive 34, so that it can also be determined whether a tumbler or a lock is implemented by means of the tumbler or not. The aforementioned states can therefore be queried by means of the corresponding circuits.

4 shows a sectional front view of the second embodiment of FIG 3. The sectional view allows a view of the components of the magnetic drive 34, as shown in FIG 3 is called.

The magnetic drive 34 has a first coil, in the form of the coil 25, and an associated armature 24 with a holding element 29. The holding element 29 is designed flat and provided for mechanically contacting the outer yoke 26 and the inner yoke 33. The armature 24 is at rest when the holding member 29 abuts the outer yoke 26 and in the locking position when the holding member 29 abuts the inner yoke 33. The use of retaining springs is not necessarily required here, but these can be used to assist. Due to the bias by the permanent magnets 27, the holding member 29 is held together with the armature 24 in the rest position. In this case, an optimal magnetic flux takes place from the permanent magnets 27 via the outer yoke 26 via the holding element 29 into the armature 4. Advantageously, the magnetic field of the permanent magnets 27 is shielded in addition by the inner yoke 33 in such a way that the outer yoke 26 is protected by a magnetization by the coil 25.

Due to the planar construction of the holding element 29, the magnetic flux between the holding member 29 and the outer yoke 26 is regulated, that is, the holding force can be adjusted in the rest position.

Upon activation of the tumbler, the coil 25 is energized, so that a magnetization in the armature 24 constructed which is opposite to the bias of the permanent magnets 27, wherein a detachment of the retaining element 29 from the outer yoke 26 leads to an abrupt termination of the magnetic holding force and thus to a substantial difference in magnetic force immediately after disengagement. The consequence is the powerful exchange of the armature 24 together with the retaining element 29 in the locking position, wherein the magnetic flux of the coil 25 is guided via the inner yoke 33 by the retaining element 29 in the armature 24. The increased magnetic force difference benefits the switching operation, in which the right switching unit 32 is safely operated.

Advantageously, a position switch, which provides support for a return spring 40, 44 for the magnetic drive, in a possible fracture of the return spring 40, 44 able to maintain the lock by the force of the permanent magnet until the first release, if it is a Spring-locking system acts.

The actuating surface 23, 30 are advantageously designed angle iron-like, that is flat with bending edges, thereby bypassing the mechanical component to important components of the position switch is possible. In particular, the actuating plate 30 thus bypasses the centrally mounted magnetic drive 34 in order to operate the left switching unit 28 with its foot 31.

5 shows a perspective view of the second embodiment of FIG 3, wherein in particular the left 28 and right switching unit 32 and the magnetic drive 34 emerge more clearly.

In summary, the invention relates to a position switch with a device for generating a magnetic force for magnetic drives with at least a first coil and at least one armature, wherein the armature by means of the first coil is magnetizable and movable. It is taught how the Magnetic force can be increased in particular to the start of movement of the movable components of the device in order to reduce the necessary power consumption of the first coil. For this purpose, the device for generating a magnetic force has at least one means for biasing the armature. This results in a number of advantages, such as a smaller design, lower power consumption and possible use with a variety of different switching units with different counter forces.

Claims (9)

Position switch with at least one coil (1, 25) and at least one armature (4, 24), wherein the armature (4, 24) by means of the first coil (1, 25) is magnetizable and movable, characterized in that the device at least a means for biasing the armature (4, 24). A position switch according to claim 1, wherein a first means for biasing is a magnetizing element (2). Position switch according to one of claims 1 or 2, wherein the magnetizing element (2, 27) is a permanent magnet and / or a second coil. Position switch according to one of the preceding claims, wherein the bias of the armature (4, 24) opposite to a magnetization of the armature (4, 24) by the first coil (1, 25). Position switch according to one of the preceding claims, wherein the armature (4, 24) is premagnetizable via a first yoke (3, 26) as a further means for biasing. Position switch according to one of the preceding claims, wherein by the first yoke (3, 26), a magnetic flux from the magnetizing element (2, 27) in the armature (4, 24) is conductive. Position switch according to one of the preceding claims, wherein a magnetic holding force upon release of a holding element (29) of the armature (4, 28) or upon release of the armature (4, 24) itself from the first yoke (3, 26) is abruptly changed. Position switch according to claim 7, wherein the holding element (29) for conducting magnetic fluxes from the first yoke (3, 26) and a second yoke (5, 33) in the armature (4, 29) is provided. Safety switch, which is designed as a position switch according to one of claims 1 to 8.

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