EP0063233B1 - Electromagnetic driving element - Google Patents

Description

The invention relates to an electromagnetic tappet drive, in which the electromagnet consists of two symmetrically constructed magnetizable yoke halves, each of which is comprised of a coil, the mutually facing pole ends of which form mutually aligned working gaps which extend in mutually parallel directions which are perpendicular to the direction of movement of one Tongue-shaped plunger which is arranged displaceably in the working gaps and which has armature webs made of magnetizable material, each of which is assigned to a working gap, the volume of the armature webs being of the order of magnitude of the working gap volume and the armature webs in the initial position of the plunger in the non-excited state of the electromagnet whose working gaps are located and are pulled into the working gap when the electromagnet is excited.

Such an electromagnetic plunger drive as described in German patent application P 2926276.8 is particularly suitable for use in impact printers.

In the European patent application 82 101 861.1 (EP-A-0 062 765), which was filed on the same day as the priority application on the same day with the present patent application, a bank for holding several pressure ram units is described.

As described and shown in P 2 926 276.8, these pressure tappet units consist of a flat frame 2-1-1 between whose legs a tongue-shaped tappet 5 runs in a recess (see FIGS. 1 and 2 of this application). At the action end of this plunger 5, a push button 5-1 is attached. The pressure tappet 5 can move in the pressure direction D marked by the arrow (or opposite thereto). Its lateral movement is prevented by the electromagnetic drive units 2-1-2 and 2-1-3 attached to the frame. These electromagnetic drive units can be attached to the frame by gluing, screwing, riveting or other conventional methods. At the rear end of the tongue-shaped plunger 5, two holes 6 are made; Likewise, two holes 9 are provided in the rear base part of the U-shaped frame. These holes 6 and 9 are used to hang two tension springs 7, which bring the deflected plunger back to its starting position. The starting position is formed by a stop 8. A pin 11, which is designed as an extension of the stop 8, is fastened in the direction of D in the base of the u-shaped frame. The plunger is accelerated in the direction of action D by activating the electromagnetic drive units. After a stop on the type of print, not shown, or the record carrier, not shown, the pressure ram is returned to its starting position by the force of the springs 7.

The principle of the electromagnetic drive, which is also the basis of the subject of the present application, is described in German patent application P 2 926 276.8 (GE 979 026). However, the embodiment of the electromagnet pairs described in this application and the design of the soft iron web structure in the tongue-shaped plunger have a number of disadvantages.

The disadvantages of the electromagnets are based on the following: The U-shaped or the yokes connected in series to form combs carry the windings on their base part. Comb-like magnetic yoke arrangements are known from German patent application P 3 018 407.7, as explained in more detail in connection with FIG. 7 of this application. This results in a greater spatial expansion of the electromagnet units in the direction perpendicular to the plane of the tongue-shaped plunger. This fact has a particularly disadvantageous effect for the desired high division density of such tappet units in a bank. Furthermore, the application of the coils to the magnetic yokes is cumbersome and expensive, and the coil parts on the outside lead to an undesirable magnetic interaction with the neighboring units.

The soft iron web structure in the tongue-shaped tappet specified in the exemplary embodiment according to P 2 926 276.8 also has a number of disadvantages. These disadvantages lie in the difficulty of simply inserting such individual soft iron webs into the tongue-shaped pressure ram body, which is otherwise made of plastic, while observing all the required tolerances.

It is therefore an object of the present invention to provide an electromagnetic tappet drive while avoiding the aforementioned disadvantages.

The improvements are said to lie in the spatial design of the electromagnet units and in the web structures to be inserted in the tongue-shaped pressure tappet body, and in a reduced interaction of neighboring electromagnet units.

This object of the invention is achieved in an advantageous manner by the measures mentioned in the characterizing part of claim 1. Advantageous developments of the invention can be found in the subclaims.

An embodiment of the invention is shown in the drawings and will be described in more detail below.

• Fig. 1 eine perspektivische vereinfachte Darstellung einer Bank zur Aufnahme mehrerer Druckstösseleinheiten gemäss der europäischen Patentanmeldung 82101 861.1 (EP-A-0 062 765),
• Fig. 2 eine vereinfachte perspektivische Exposionszeichnung einer Druckstösseleinheit mit den ihr zugeordneten beidseits ihres Rahmens angeordneten elektromagnetischen Antriebseinheiten für den zungenförmigen Stössel,
• Fig. 3 eine schematische vereinfachte Darstellung zum Prinzip des Druckstösselantriebes gemäss der deutschen Patentanmeldung P 2 926 276.8,
• Fig. 4 eine Explosionszeichnung einer Druckstösseleinheit mit zugehörigen erfindungsgemässen elektromagnetischen Antriebseinheiten,
• Fig. 5 eine Schnittdarstellung durch die Stegstruktur entlang der Schnittlinie A-A in Fig. 4,
• Fig. 6 ein zungenförmiger Stössel mit einer anderen Ausführungsform der magnetischen Stege als in Fig. 4 und Fig. 5,
• Fig. 7 eine schematische perspektivische Prinzipdarstellung eines Stösselantriebes, bei dem ein zylinderförmiger Druckstössel in den kreisförmig ähnlichen Arbeitsspalten zweier gegenüberliegender Jochhälften verläuft.

Show it:

• 1 is a perspective, simplified representation of a bench for receiving a plurality of pressure ram units according to European patent application 82101 861.1 (EP-A-0 062 765),
• 2 is a simplified perspective exploded view of a pressure ram unit with the associated electromagnetic drive units for the tongue-shaped ram arranged on both sides of its frame,
• 3 shows a schematic, simplified illustration of the principle of the pressure ram drive according to German patent application P 2 926 276.8,
• 4 shows an exploded view of a pressure ram unit with associated electromagnetic drive units according to the invention,
• 5 shows a sectional view through the web structure along the section line AA in FIG. 4,
• 6 shows a tongue-shaped plunger with a different embodiment of the magnetic webs than in FIGS. 4 and 5,
• Fig. 7 is a schematic perspective illustration of a tappet drive, in which a cylindrical pressure tappet runs in the circularly similar working gaps of two opposite yoke halves.

3 shows a schematic perspective illustration of an electromagnetic pressure tappet drive according to German patent application P 2 926 276.8. A tongue 28 movable in the direction of arrow D is arranged between two fixed stator halves 25, 22. The stator halves 25 and 22 each consist of a magnetizable yoke 27 and 24, which is encompassed by coil turns 26 and 23, respectively. The stator yokes can e.g. B. be semicircular, semi-elliptical or U-shaped. The stator yokes 27, 24 in the two stator halves 25 and 22 are aligned such that the respectively opposite yoke ends are aligned. When the coils 26 and 23 are excited, the magnetic flux runs from one yoke over a working gap to the yoke of the other half of the stator and from there via another working gap back to the first-mentioned yoke, so that the magnetic circuit consists of the two stator yokes and the one between the ends of the Stator yokes are two working columns.

For the sake of simplicity, the following text refers to a stator pair (instead of a stator half pair) in the opposing stator halves.

The current flow in the excitation coils 26 and 23 takes place in such a way that the current direction in the windings within the two opposing stator yokes is the same and opposite to that in the windings outside the stator yokes. In Fig. 3, the windings are indicated schematically by a few wire loops in the front part of the illustration, while a corresponding sectional illustration of the wires was selected in the rear part. The tongue 28, which is arranged movably in the direction of arrow D between the stator halves 25 and 22, is expanded in the direction of the working gap to be much smaller than in its other two dimensions. The body of the tongue 28 consists of a light, magnetically non-conductive material 29 and magnetically conductive, so-called anchor webs 30 and 21. These anchor webs are arranged in the tongue 28 in such a way that when the stator halves are excited from a rest-starting position the space formed between the stator yokes is drawn in and thereby accelerated. The tongue can then follow a further movement in the direction of arrow D. The design of the anchor webs 30 and 21 is essentially chosen so that their volume would approximately fill the space circumscribed between the ends of the stator yokes.

The distance covered by the tongue from the initial position to the position after the acceleration phase has ended (when the anchor bridge is in the working gap) is referred to as the acceleration stroke; the sum of the acceleration stroke and the subsequent further deflection of the tongue in the direction of arrow D as the working stroke. This size depends on the structural boundary conditions and on the means provided for storing the tongue or for returning the tongue to its initial position. Known return springs (not shown) can be used as such means: e.g. two leaf springs, as described in DAS 1237816: a spring in cooperation with a slide bearing of the tongue or a return spring in cooperation with a tongue which can be pivoted about an axis. Electromagnetic feedback is also possible.

It can be seen from the illustration in FIG. 3 that the coil turns run around the base of the U-shaped yoke halves. In other words, the turns are arranged inside and outside the pair of yokes. The effort to attach such windings and the associated space requirements are relatively high. To avoid these disadvantages, the subject matter of the present application therefore makes use in particular of an inventive design of the yoke halves in connection with the attachment of the windings.

In this context, it should be pointed out that the U-shaped yoke halves in German patent application P 3 018 407.7 (GE 980 014), as shown in FIG. 7, can also be connected in series, but the excitation winding there, too, only comprises their base .

An electromagnet with a working gap described in German Patent Application P 3 018 407.7 (GE 980 014), into which an element containing a displaceable soft magnetic material is drawn when the electromagnet is excited, is characterized in that the electromagnet (95) consists of two magnetizable yoke halves (96 , 97, 99; 108, 109, 98), of which at least one is enclosed by a coil (100), that the mutually facing, substantially semicircular, recessed pole ends of the yoke halves form essentially circular working gaps (101, 102), that between the pole ends of the yoke halves there is arranged a plunger (91) which can be displaced in the direction of the line of alignment of the working gap and which has a cross section adapted to the surface of the working gap, that the plunger (91) has two armature disks (92, 93) made of magnetizable material and one between them anchor disks (92, 93) arranged spacer element (94) made of predominantly non-magnetizable material that each working gap (101, 102) is assigned an armature disk (92, 93) that the armature disks (92, 93) have such a geometric design, that their volume is of the order of magnitude of the space between the mutually facing pole ends of the yoke halves, and that the armature disks (92, 93) are in the initial position of the plunger (91) in the non-excited state of the electromagnet in front of its working gaps (101, 102) and be pulled into this working gap when the electromagnet is excited.

1 shows a perspective view of a bench for receiving a plurality of pressure ram units. The pressure ram units, of which only four (for the sake of simplicity) (without the pressure ram) are shown with 2-1, 2-2, 2-3 and 2-4. The frames of these pressure ram units bear the reference numbers 2-1-1, 2-2-1, 2-3-1 and 2-4-1. Each pressure tappet unit has a pair of electromagnetic drive units for the pressure tappet. The electromagnetic drive units for the pressure ram unit 2-1 are designated 2-1-2 and 2-1-3 and are arranged on both sides of the frame 2-1-1 in an aligned manner.

Electromagnetic drive units, as can be used for the bank described here, are described in the German patent application P 2 926 276.8.

From the illustration in Fig. 1 it can be seen how the individual pressure ram units are accommodated in the print hammer bank. The print hammer bank consists of a lower part 1-1 and an upper comb-like part 1-2. In the following, the lower part 1-1 is referred to as the base part and the upper part 1-2 as the comb part. The base part is composed of two rails 1-1-1, 1-1-2 running parallel to one another and a part 1-1-3 provided with slots 4 between them. The slots run parallel to each other and are limited in length by the rails 1-1-1 and 1-1-2. They serve to accommodate a lower extension (see FIGS. 2 and 4) of the pressure ram frame.

The comb part 1-2 of the bench consists of a beveled (1-2-1) part which has comb-like incisions 3 on its side tapered by the bevel. These comb-like incisions 3 are aligned with the slots 4 in the base part 1-1. Each of these comb-like incisions 3 comprises part of the upper edge of the frame of the individual ram units. The individual ram units are thus fixed in their position. Lateral evasion is prevented by the slots 4 or the comb-like incisions 3; A vertical evasion is not possible due to the position of the pressure tappet units between the base part 1-1 and the comb part 1-2, while evasion in the direction of action of the pressure tappet (not shown) parallel to the direction of the slots 4 or in the opposite direction by appropriate accommodation of the lower one Frame approach (2-1-7; 14) in the slots 4 can be prevented or influenced in the desired manner. The latter is particularly important for those cases in which you want to cause the plunger to rebound on the pressure hammer bench. Further details are given in connection with FIG. 2.

It has already been mentioned that on both sides of the frame, e.g. 2-1-1 of the pressure ram unit 2-1, an electromagnetic drive unit 2-1-2 and 2-1-3 is arranged in a mutually aligned form. In order to achieve a tight packing density of the pressure rams in the bank, the electromagnetic drive units are offset in pairs for pressure ram units lying next to one another, so that the distance between two frames lying next to one another is determined by the strength of an electromagnetic working unit. As can be seen from the illustration in FIG. 1, the electromagnetic drive units 2-1-2 / 2-1-3 of the pressure plunger units 2-1 are compared to the electromagnetic drive units 2-2-2 / 2-2-3 of the pressure plunger unit 2 -2 offset accordingly.

For reasons of clarity, the electromagnetic drive units for the pressure ram unit 2-3 are not shown in FIG. 1.

The illustrations in FIG. 1 and FIG. 2 come from European patent application 82 101 861.1 (EP-A-0 062 765), which was filed on the same day as the present patent application.

While the European patent application 82101 861.1 relates to a bench for accommodating pressure ram units, the particulars in the design of the electromagnetic drive units for the pressure ram units are described in the present application. Details on this are shown in FIGS. 4, 5 and 6.

FIG. 4 shows an exploded view of a pressure ram unit with associated electromagnetic drive units. Many parts of FIG. 4 correspond to the parts with the same reference numerals in FIGS. 1 and 2. In order to avoid repetitions, they are not dealt with in the explanation of FIG. 4, or only briefly.

The tongue-shaped joint 5, the base body of which is made of plastic, is provided with bores 31 at various points for reasons of weight. The soft iron bars required for the effectiveness of the electromagnetic drive are shown at 60, 61 and 62. The electromagnetic drive units 2-1-2 and 2-1-3, which are fastened on both sides of the frame 2-1 in an aligned form, each contain a magnet yoke 41, 51 and an associated excitation coil 45, 55. The magnet yoke combinations are 40 and 50 marked. Each of these combinations is accommodated by a housing 140, 150 with a corresponding plug connection 141, 151 with the contacts 142, 152 for the excitation coils 45 and 55. These housings are connected to the frame by means of screws (not shown) or other suitable fastening means. Corresponding mounting holes are designated in the housing 150 with 32-1 and 33-1 and in the frame 2-1 with 32 and 33. The fastening elements, which are not shown for reasons of clarity, ensure exact positioning of the electromagnetic drive units, in particular the working gaps in relation to the soft iron webs 60, 61, 62 in the tongue-shaped plunger 5. As mentioned in connection with patent application P 2 926 276.8, a magnetizable web must be provided stand in front of a working gap when the electromagnets are not excited.

In the present case, the magnet yokes 41 and 51 have an E-shaped cross section. The opposite E-shaped magnet yokes 51 and 41 are aligned so that a total of 3 working gaps are formed by their leg ends 52, 53, 54 and 42, 43, 44: the first working gap lies between the leg ends 52 and 42, the second between the Leg ends 53 and 43 and the third between the leg ends 54 and 44. One of the three magnetizable webs 62, 61 and 60 is assigned to each of these working gaps. The excitation winding for each magnetic yoke runs, as shown in FIG. 4, around the middle E-leg in such a way that the excitation coil can be manufactured separately as a flat slip-on coil for the middle E-leg, with the winding strands running parallel in the through the Legs formed spaces must fit.

This special design of the magnetic yoke excitation coils is extremely inexpensive and space-saving. The coil expansion does not extend in the direction perpendicular to the plunger plane beyond the magnetic yoke. This fact is particularly noteworthy for a high packing density with little magnetic interaction of the pressure ram units in banks. In addition, the flat coil and the E-shaped magnetic yoke allow simple and inexpensive production of the individual parts and easy assembly of the two parts. The magnetic yoke coil combination 50 is inserted into a corresponding recess 34 in the housing 150 and is potted there with the housing with plastic. The same applies to the magnetic yoke coil combination 40 and the housing 140. At this point, it should be expressly emphasized that, for an exact operation of the pressure ram drive, the soft iron webs in the pressure ram 5 should be assigned to the corresponding working gaps of the electromagnets with as little tolerance as possible. This also results in requirements for the problem-free insertion of the magnetizable webs into the plastic base body of the plunger 5.

In principle, it can be assumed that these webs can be inserted into the plastic body relatively easily and cast with it. On the other hand, an exact arrangement of the webs relative to one another is more problematic. For this reason, the webs should not be inserted into the ram individually, but as a coherent common part. There are various alternatives for the structure of such a part, such as. B. shown in Figs. 5 and 6.

5 shows a structure in which the magnetizable webs 60, 61 and 62 are continuously connected with the same magnetizable material of thinner thickness. The webs 60 and 61 are connected via the connection 63 and the webs 61 and 62 via the connection 64. Such connections 63, 64 between the webs are undesirable for optimal operation of the drive. It has been found, however, that with a correspondingly thin thickness of these compounds, their disadvantageous influence on the efficiency is only slight and that this influence can, in practical terms, be readily accepted. This makes it possible to produce the web structure as a coherent part and to simply embed this part in the tongue-shaped plunger 5. Here you only have to take into account the correct fitting of this one part into the plunger 5 (and not the three individual bars). After inserting this part into a corresponding recess in the plunger, it is cast with plastic, and the previously empty recesses (64, 65) of the part are also filled with plastic up to the plunger level.

Another web structure is shown in FIG. 6. The plunger itself is labeled 70, the plunger head again 5-1. The holes for receiving the tension springs (not shown) (see FIG. 4) have the reference number 6 and those material-saving bores have the reference number 31 as in FIG. 4.

The web structure 71 itself has the shape of a longitudinally and transversely divided rectangular frame with four openings 72. The frame parts essential for the tappet drive are the webs 73, 74 and 75. The webs 73 and 74 are due to the frame parts 76, 77 and 78 lying transversely thereto made of the same material as the web material; Likewise, the webs 74 and 75 are connected by the frame parts (same material) 79, 80 and 81 lying transversely thereto. The transverse frame parts are narrower and thinner than the webs themselves - the frame openings are potted with plastic up to the ram level.

Claims (5)

1. Electromagnetic ram actuator, wherein the electromagnet consists of two essentially symmetrically designed magnetizable yoke halves embraced by one coil each, whose pole ends facing each other form aligned operating gaps extending in directions parallel to each other and perpendicularly to the direction of movement of a tongue- shaped ram shiftable in the operating gaps and comprising armature bars of magnetizable material, each of which is associated with one operating gap, and wherein the volume of the armature bars is approximately equal to the volume of the operating gaps, and the armature bars, in the starting position of the ram, are positioned in front of the operating gaps when the electromagnet is in a non-energized state and upon energization of the electromagnet are pulled into the operating gaps, characterized in that the yoke halves (41,51) perpendicular to the ram's plane of movement in its direction of movement have an E-shaped cross- section, and the windlings of the coils (45, 55) energizing the yoke halves (41, 51) essentially extend between the E-legs (44, 43, 42; 54, 53, 52) of the yoke halves (41, 51).

2. Electromagnetic ram actuator, wherein the electromagnet consists of two essentially symmetrically designed magnetizable yoke halves embraced by one coil each, whose pole ends facing each other form aligned operating gaps extending in directions parallel to each other and perpendicularly to the direction of movement of a tongue- shaped ram shiftable in the operating gaps and comprising armature bars of magnetizable material, each of which is associated with one operating gap, and wherein the volume of the armature bars is approximately equal to the volume of the operating gaps, and the armature bars, in the starting position of the ram, are positioned in front of the operating gaps when the electromagnet is in a non-energized state and upon energization of the electromagnet are pulled into the operating gaps, characterized in that the armature bars (60, 61,62,73,74,75) are interconnected by transverse connecting means (63, 64, 76, 77, 78, 79, 80, 81) made of the same magnetizable material as themselves to form a continuous element.

3. Arrangement according to claim 2, characterized in that the transverse connecting means (63, 64, 76, 78, 79, 81) are narrower than the armature bars (80, 61, 62, 73, 74, 75) in the direction of the alignment of the pole ends of the yoke halves

4. Arrangement according to claim 2 or 3, characterized in that the transverse connecting means (76, 77, 78, 79, 80, 81) are narrow interconnecting strips between the armature bars (73, 74, 75).

5. Arrangement according to claim 3, characterized in that the transverse connecting means (76, 77, 78, 79, 80, 81) and the armature bars (73, 74, 75) have an essentially four-quadrant- shaped frame structure.

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