EP2342726B1 - Contactor for an electric starter and method for switching the contactor - Google Patents

Description

State of the art

The invention relates to an electromagnetic switch for a starting device and a method for operating the electromagnetic switch.

From the German patent application DE 195 49 179 A1 is an electromagnetic switch (engagement relay) known for a starting device This switch has two contacts, which are referred to there as contact pins. Both contacts are electrically conductively connected to each other by a movable contact bridge in order to forward current from the contact pin, which is connected to a positive pole of a starter battery, to a contact pin and thereby to conduct electrical potential to a starter motor, which is not shown there in detail. From the DE 10 2004 017160 A1 Another relay for starting devices is known. This relay has a so-called selbstfedernde contact bridge, in which after the contact between the contact bridge and the mating contacts by the elasticity of the contact bridge, a transverse force between the contact bridge or the surface and the mating contacts arises.

The document FR2861891 shows a switch according to the preamble of claim 1.

In contrast, the contact between contact bridge and mating contacts should be further improved.

Disclosure of the invention

The proposed solutions seek to create a scraping motion between the two contact surfaces between the contact surfaces of the contacts and the surface of the contact bridge, thereby removing soils and other by the switching movement. All initially four alternatives have in common that the electromagnetic switch has two contacts, which are electrically conductively connected to each other by a movable contact bridge. Furthermore, this is common to the fact that the at least one contact has a contact surface. With the first alternative, it is provided that the contact surface is at least substantially planar and an electrical contact between the contact bridge and the contact-giving edge of the contact bridge is arranged such that the latter contacts This has the advantage that compared to the previously known solutions, a relatively high surface pressure between the two contact-giving elements can be achieved. This is a prerequisite for a high-quality cleaning effect between the contact surfaces and for a possible good scraping action between contact bridge and contact surface.

According to the second alternative, it is provided to achieve at least one point contact between contact and contact bridge. For this purpose, it is provided that the contact surface of the contact has elevations whose highest areas lie substantially in one plane. An electrical contact between the contact bridge and contact edge of the contact bridge is arranged so that, starting from the impact on the contact surface, it essentially enables at least one point contact between the contact and the contact bridge

Substantially "line contact" and essentially "point contact" means that the contact pads between contact bridge and contact are very narrow and relatively long in a substantially line contact. A point contact means that the current passage area between contact bridge and contact is at least one contact surface. if necessary reduced several - very small area, which is nearly a point

According to the third alternative, it is provided that a contact surface of the contact bridge and an axis of a contact pin between them include an angle directed to a central axis of the switch, which is greater than 90 °. This definition applies z. B. for the rest position of the electromagnetic switch.

A fourth alternative describes that a contact face of the contact bridge and an axis of the contact pin between them include an angle directed radially outward with respect to a central axis of the switch, which is greater than 90 °. This definition also preferably applies to the rest position of the electromagnetic switch.

As the central axis of the switch, for example, the axis can be considered, around which, for example, a retraction or a holding winding of the electromagnetic switch is wound. This axis is usually synonymous with the central axis of a magnetic core of the electromagnetic switch.

According to the above alternatives, it is possible to reduce the bounce of the contact bridge when hitting the contacts to be connected, since the friction is generated between the contact partners in the contacting. This leads to a reduction in the arc tendency and thus to reduce the surface temperatures of contact and contact bridge. As a result, the wear of the contact bridge and the contact is reduced, since less arc erosion arises For the very rare case of cohesive connections, the alternatives mentioned allow an additional lateral force on the respective compound, so that in the end the opening force or the force in this connection acts, is increased. The friction between the contact partners, contact bridge and contact, destroys non-conductive layers on the surfaces, so that in the sequence of clean contacts arise because any oxide layers and / or ice sheets are broken. In addition, the mass of the contact bridge can be reduced, so that sets a lower bounce in the sequence.

Further advantages emerge from the subclaims.

According to the invention, it is provided that in order to achieve a point contact, the contact surface of the contacts has a corrugation, which is preferably a straight corrugation or a corrugation

For the third alternative it is provided that the angle between 91 ° and 105 °, preferably by 95 °. According to the fourth alternative, it is provided that the angle is between 91 ° and 120 °.

Regarding the design of the edge of the contact bridge is provided that the edge is arcuate or straight Particularly insensitive to tolerances is the arcuate edge. As a result, tilting in particularly material-saving designs practically does not occur.

In order to keep a shock load between the contact bridge and the contacts that are touched by the contact bridge as low as possible, it is provided that on the one hand, the contact bridge is guided by a bolt in a bearing and the contact bridge between the pin and the edge of an area with the largest cross section and between the region with the largest cross section and the bolt has a reduced cross-section area. This increases the flexural elasticity.

To produce the most effective transverse movement of the contacting contact surfaces of the contact bridge and contact is provided that the contact bridge consists of a perpendicular to the bolt oriented central planar portion, followed by the bolt pioneering at least one outer surface section between the central and the outer Section is an angle that is not equal to 90 °. In order to achieve the best possible durability of the contact bridge, it is provided that at least one of the two contacts has a hardness which is less than a hardness of the contact bridge. Furthermore, it is provided that a friction coefficient between the contact bridge and the at least one contact has a value between 0.1 and 2, preferably between 0.6 and 1. To achieve a Particularly good scraping action is provided that the edge has a radius of less than 0.3mm. Furthermore, it is provided that the contact bridge is a metal sheet, which preferably has a plate thickness of between 1 and 4 mm. In the case of the third alternative it is provided that the contact surface of the contact bridge contacts one edge of the contact

In the event that is contacted by the contact bridge by means of an edge, it is provided that the contact bridge has several edges that contact the contact. To optimize the contact bridge is provided that it consists of several layers. Preferably, a carrier layer is provided and a contact layer attached to the carrier layer. The support layer should preferably consist of a copper or silver alloy or steel or bronze or brass, while the contact layer of copper, tin, gold or silver alloy or a metal-metal oxide composite material exist.

There is provided a starting device with an electromagnetic switch as described. The switch is particularly advantageous in that it can be used to reduce switching problems, especially in high current applications such as starters.

According to another subclaim, it is provided that either the contact bridge slides with its surface in the form of an edge over the contact surface of the contact or the contact surface of the contact with its surface in the form of an edge slides over the contact bridge. In the event that a cohesive connection between the contact bridge and a contact is formed, it is provided that a sufficiently large thrust load in the cohesive connection dissolves them

Furthermore, a method is provided with which the electromagnetic switch is switched. There are two contacts connected by a movable contact bridge. When contacting the contact bridge with at least one of the two contacts, a scraping movement acts between the contact bridge and the contact surface of the contact. scraping means that a sliding movement (friction movement) acts between the contact bridge and the contact surface of the contact.

Short descriptions of the drawings

The invention is explained in more detail below by way of example with reference to the figures:

• Figur 1 eine Startvorrichtung in einem Längsschnitt,
• Figur 2 zeigt einen Längsschnitt durch den elektromagnetischen Schalter gemäß einem ersten Ausführungsbeispiel,
• Figur 3 zeigt eine Seitenansicht einer Kontaktbrücke,
• Figur 4 zeigt eine Draufsicht einer Kontaktbrücke,
• Figur 5 zeigt drei verschiedene Querschnitte der Kontaktbrücke gemäß dem ersten Ausführungsbeispiel aus den Figuren 3 und 4,
• Figur 6 eine Draufsicht auf den Kontakt eines Bolzens,
• Figur 7 eine Schnittdarstellung eines Kontakts eines Bolzens gemäß Figur 6,
• Figur 8 eine Seitenansicht eines Kontaktbolzens 151 und einer Kontaktbrücke gemäß einem zweiten Ausführungsbeispiel,
• Figur 9 eine zweite Seitenansicht des zweiten Ausführungsbeispiels gemäß Figur 8,
• Figur 10 eine Seitenansicht eines dritten Ausführungsbeispiels,
• Figur 11 ein viertes Ausführungsbeispiel eines Schalters mit einer anderen Position der Kontaktbrücke,
• Figur 12 zeigt prinzipiell ein fünftes Ausführungsbeispiel als Abwandlung des Ausführungsbeispiels nach Figur 2,
• Figur 13 zeigt ein sechstes Ausführungsbeispiel einer Paarung von Kontaktbolzen mit einer Kontaktbrücke,
• Figur 14 zeigt ein siebtes Ausführungsbeispiel einer Paarung von Kontaktbrücke und Kontaktbolzen,
• Figur 15 zeigt ein achtes Ausführungsbeispiel einer Paarung aus einer Kontaktbrücke und zwei Kontaktbolzen,
• die Figur 16 und die Figur 17 zeigen je ein alternatives Ausführungsbeispiel einer Kontaktbrücke,
• Figur 18 und Figur 19 zeigen zwei weitere Alternativen für Kontaktbrücken,
• Figur 20 zeigt eine Schnittdarstellung einer hier prinzipiell dargestellten Kontaktbrücke,
• Figur 21 zeigt eine Seitenansicht bzw. Schnittdarstellung der erfindungsgemäßen Kombination aus Kontaktbrücke und Kontaktoberfläche,
• Figur 22A zeigt ein Diagramm, in dem Abhängigkeiten verschiedener Parameter dargestellt sind,
• Figur 22B zeigt eine halbe Kontaktbrücke mit verschiedenen Maßen, die für Figur 21A von Bedeutung sind.

Show it

• FIG. 1 a starting device in a longitudinal section,
• FIG. 2 shows a longitudinal section through the electromagnetic switch according to a first embodiment,
• FIG. 3 shows a side view of a contact bridge,
• FIG. 4 shows a plan view of a contact bridge,
• FIG. 5 shows three different cross sections of the contact bridge according to the first embodiment of the FIGS. 3 and 4 .
• FIG. 6 a plan view of the contact of a bolt,
• FIG. 7 a sectional view of a contact of a bolt according to FIG. 6 .
• FIG. 8 a side view of a contact pin 151 and a contact bridge according to a second embodiment,
• FIG. 9 a second side view of the second embodiment according to FIG. 8 .
• FIG. 10 a side view of a third embodiment,
• FIG. 11 A fourth embodiment of a switch with a different position of the contact bridge,
• FIG. 12 shows in principle a fifth embodiment as a modification of the embodiment according to FIG. 2 .
• FIG. 13 shows a sixth embodiment of a pairing of contact pins with a contact bridge,
• FIG. 14 shows a seventh embodiment of a pairing of contact bridge and contact pins,
• FIG. 15 shows an eighth embodiment of a pairing of a contact bridge and two contact pins,
• the FIG. 16 and the FIG. 17 each show an alternative embodiment of a contact bridge,
• FIG. 18 and FIG. 19 show two further alternatives for contact bridges,
• FIG. 20 shows a sectional view of a contact bridge shown here in principle,
• FIG. 21 shows a side view or sectional view of the combination of contact bridge and contact surface according to the invention,
• Figure 22A shows a diagram in which dependencies of various parameters are shown,
• Figure 22B shows half a contact bridge with different dimensions, which for Figure 21A are of importance.

Embodiments of the invention

FIG. 1 shows a starting device in a longitudinal section. In the FIG. 1 a starter 10 is shown. This starting device 10 has, for example, a starter motor 13 and an electromagnetic switch 16, which is designed here as an engagement relay. The starter motor 13 and the switch 16 are fixed to a common drive end plate 19. The starter motor 13 is functionally to drive a starter pinion 22 when it is meshed in the ring gear 25 of the internal combustion engine, not shown here

The starter motor 13 has a pole tube as a housing 28, which carries on its inner circumference pole pieces 31, which are each wrapped by a field winding 34. Instead of electrical excitation, a permanent magnetic excitation of the stator comes into question. The pole pieces 31 in turn surround an armature 37, which has an armature packet 43 constructed from fins 40 and an armature winding 49 arranged in grooves. The armature packet 43 is pressed onto a drive shaft 44. At the end of the drive shaft 44 facing away from the starting pinion 22, there is further a commutator The commutator bars 55 are electrically connected in a known manner to the armature winding 49 in such a way that, when the commutator bars 55 are energized by carbon brushes 58, a rotational movement of the armature 37 in the pole tube 28 results. A arranged between the Einspurrelais 16 and the starter motor 13 power supply 61 supplies in the on state Both the carbon brushes 58 and the field winding 34 with power. The drive shaft 44 is commutator side supported with a shaft journal 64 in a sliding bearing 67, which in turn is held stationary in a commutator bearing cover 70. The commutator 70 is in turn secured by means of tie rods 73 which are arranged distributed over the circumference of the pole tube 28 (screws, for example, 2, 3 or 4 pieces) in the drive bearing plate 19. It supports the pole tube 28 on the drive bearing plate 19, and the commutator bearing cover 70 on the pole tube 28.

In the drive direction, the armature 37 is adjoined by a so-called sun gear 80, which is part of a planetary gear 83. The sun gear 80 is surrounded by a plurality of planetary gears 86, usually three planet gears 86, which are supported on axle journals 92 by means of rolling bearings 89. The planet gears 86 roll in a ring gear 95, which is mounted outside in the pole tube 28. Towards the output side, the planet wheels 86 are adjoined by a planetary carrier 98, in which the axle journals 92 are accommodated. The planet carrier 98 is in turn stored in an intermediate storage 101 and a slide bearing 104 arranged therein. The intermediate bearing 101 is designed cup-shaped, that in this both the planet carrier 98, and the planet wheels 86 are added. Furthermore, the ring gear 95 is arranged in the cup-shaped intermediate bearing 101, which is ultimately closed by a cover 107 relative to the armature 37. Also, the intermediate bearing 101 is supported with its outer circumference on the inside of the pole tube 28. The armature 37 has on the end facing away from the commutator 52 end of the drive shaft 44 has a further shaft journal 110, which is also received in a sliding bearing 113, from. The sliding bearing 113 in turn is received in a central bore of the planet carrier 98. The planetary carrier 98 is integrally connected to the output shaft 116. This output shaft 116 is supported with its end 119 facing away from the intermediate bearing 101 in a further bearing 122, which is fixed in the drive end plate 19, the output shaft 116 is divided into different sections: Thus follows the section which is arranged in the sliding bearing 104 of the intermediate bearing 101, a portion with a so-called spur gear 125 (internal teeth), which is part of a so-called WellenNabe connection. This shaft-hub connection 128 in this case allows the axially straight sliding of a driver 131. This driver 131st is a sleeve-like extension which is integral with a cup-shaped outer ring 132 of the freewheel 137 This freewheel 137 (directional locking mechanism) further consists of the inner ring 140 which is disposed radially within the outer ring 132 between the inner ring 140 and the outer ring 132 clamping body 138 are arranged , These clamp bodies 138, in cooperation with the inner and outer rings, prevent relative rotation between the outer ring and the inner ring in a second direction. In other words, the freewheel 137 allows a relative movement between inner ring 140 and outer ring 132 in one direction only. In this embodiment, the inner ring 140 is formed integrally with the starter pinion 22 and its helical teeth 143 (external helical teeth)

For the sake of completeness, the single-track mechanism should be mentioned here ( Fig. 1 and Fig. 2 ). The switch 16 has a bolt 150 which carries an electrical contact 181 and which is connected to the positive terminal of an electric starter battery, which is not shown here. This bolt 150 and also a bolt 151 is passed through a relay cover 153. This relay cover 153 terminates a relay housing 156, which is fastened by means of a plurality of fasteners 159 (screws) on the drive end plate 19 in the Schalter16 also a pull-in winding 162 and a so-called holding coil 165 is arranged. The pull-in winding 162 and the holding winding 165 both cause an electromagnetic field in the switched-on state, which flows through both the relay housing 156 (made of electromagnetically conductive material), a linearly movable armature 168 and an armature return 171. The armature 168 carries a push rod 174 which is in the linear position Indentation of the armature 168 is moved in the direction of a switching pin 177. With this movement of the push rod 174 to the switching pin 177 this is moved from its rest position in the direction of contact 181 and a contact 180, so that attached to the contacts 180 and 181 end of the switching pin 177 contact bridge 184 connects both contacts 180 and 181 electrically , As a result, electric power is supplied from the bolt 150 via the contact bridge 184 and the bolt 151 to the power supply 61 and thus to the carbon brushes 58. The starter motor 13 is energized

The Schaher16 or the anchor 168 but also has the task of moving a traction element 187 a drive bearing plate 19 rotatably arranged lever. This lever 190, usually designed as a fork lever, surrounds with two "tines" not shown here on its outer circumference two discs 193 and 194 to move a trapped between these driver ring 197 to the freewheel 137 back against the resistance of the spring 200 and thereby the starter pinion 22 einzuspuren in the ring gear 25.

The FIG. 2 further shows a contact release spring 220 which pushes the contact bridge 184 back to its initial position with respect to the holding winding 165 after the power has been cut off. The contact release spring 220 presses against a collar 223 which sits on the shift pin 177. The contact bridge 184 has in its center a hole 226, with which the contact bridge 184 is supported on a sleeve portion 229 of an axially movable guide collar 232. This guide collar 232 has between its outer contour and the switching pin 177 a substantially cylindrical cavity 235, in which in turn a compression spring 238 is supported. This compression spring 238 is supported on the end facing away from the contact bridge 184 of the switching pin 177 on a snap-on sleeve 241 which holds in place with snap elements 244 in a groove 247 between the armature 168 and the armature circuit 171 acts around the snap sleeve 241 around another pressure spring 250th

In FIG. 3 FIG. 2 shows a side view of the contact bridge 184. This contact bridge 184 shows a central areal section 270, which has the hole 226 in its center ( FIG. 4 ). From this central flat portion 270, which is perpendicular to the shift pin 177, radially outwardly from the center of the hole 226 outwards and thus starting from the shift pin 177 groundbreaking initially an outer surface portion 273 at. Diametrically opposed to this first outer surface portion 273 is a second outer surface portion 276. Both outer planar sections 273 and 276 have an approximately circular contour. Compared with the central planar section 270, both outer planar sections 273 and 276 are deflected by the angle α. This angle α preferably has a value between 1 ° and 15 °, with 5 ° being preferred. The outer plane Portions 273 and 276 have an edge 279 at their furthest from the center of the hole 226.

As a special embodiment, it is provided for the contact bridge 184 that this consists of so-called electro-copper (E-Cu57). Furthermore, it is provided that the angle α is equal to 5 °, the hardness of the material between 100 to 130 HV 10 has (Vickers hardness measurement method). For the material thickness d 2mm are provided. The length L of the contact bridge 184 is chosen so that the contacting of the edges 279 takes place on the contacts 180 and 181, respectively. The rigidity of the contact bridge 184 is between 150 N / mm and 250 N / mm.

In the FIG. 5 three different cross sections of the contact bridge 184 are shown. The lower part of the FIG. 5 shows the widest cross section 290 at the widest point of the outer surface portion 273. The middle part of FIG. 5 shows the cross section 293 at the interface between the outer surface portion 273 and the central surface portion 270. At this point, the contact bridge 184 is fitted. The topmost area of the FIG. 5 shows the cross section 296, which is divided into two partial surfaces 297. The cross section BB shows the cross section 296, which occurs at the widest point of the contact bridge 184 and at the same time cut centrally through the hole 226 FIGS. 2, 3, 4 . 5 Accordingly, show that the contact bridge 184 is guided by means of a switching pin 177 in a bearing in the form of a guide collar 232 and the contact bridge 184 between the switching pin 177 and the edge 279 a region with the largest cross section 290 and between the region with the largest cross section 290th and the shift pin 177 has a reduced cross-sectional area 293

With regard to the different cross sections 290, 293 and 297, it is provided that for the sum of the cross sections 297 it should be assumed that they are greater than or equal to the cross section 293.

FIG. 6 shows a plan view of the contact 180 of the bolt 151. As can be seen there, the pin 151 shown there is equipped with a contact 180, the contact surface 300 has a corrugation, the one Ring corrugation 310 is. This contact surface 300 or its corrugation is such that, as in FIG. 7 represented, in the cross-sectional view results in a wavy contour. This wavy contour can be, for example, a sinusoidal profile or a similar profile with a wave shape, ie one with "valleys and mountains". The corrugation shown here is an annular corrugation 310, ie the corrugated contour 303 or its "peaks and valleys" are in the example oriented coaxially about the center line 306 of the bolt 151

In the context of the second embodiment, FIG. 8 and following, is a contact bridge 184, as they are made FIG. 4 is known, paired with a contact pin 151, the contact surface 300 does not consist of an annular corrugation 310, but from a Gererrriff 309, FIG. 8 , In the FIG. 8 Plotted section line IX-IX is in FIG. 9 shown. Accordingly, there is shown the section through the contact pin 151, the associated bolt head 152 and the contact 180. As shown there in section, it recognizes there the Geradriffelung 309, on which the edge 279 of the contact bridge 184 is arranged

With reference to FIG. 8 is there drawn, as various sections during switching, ie contact between contact bridge 184 and the contact 180 are moved. So the arrow on the right shows the FIG. 8 labeled V ₁₈₄ , that is, the movement of contact bridge 184 to make contact between contact 180 and contact bridge 184. Upon impact of edge 279 on contact 180, edge 279 moves through the movement of contact bridge 184 and the angle of inclination α between the outer sheet portion 273 and the central sheet portion 270 in a short movement in the direction of the arrow labeled V ₂₇₉ . In reference to FIG. 9 this means a sliding of the edge 279 in the direction of the observer on the straight corrugation 209.

The first embodiment and also the second embodiment show an electromagnetic switch 16 for a starting device 10, said electromagnetic switch 16 has two contacts 180 and 181, which are electrically conductively connected to each other by a movable contact bridge 184. It is thereby provided that at least one of the two contacts 180 or 181 is preferably fixed to a contact pin 151 or 150 connected contact surface 300 has. In this case, the contact surface 300 has elevations, which preferably lie substantially in one plane. An electrical contact between the contact bridge 184 and the contact-giving edge 279 of the contact bridge 184 is arranged so that, when it strikes the contact surface 300, it essentially enables multiple point contact between contact 180, 181 and contact bridge 184. Depending on the orientation of the straight corrugation 309 or relative position of the individual elevations of the straight corrugation 309 to the edge 279, initially only a single point contact between contact 180 or 181 and contact bridge 184 may be possible.

The straight corrugation 309 should ideally be designed as sinusoidal longitudinal corrugation. With regard to the interaction of contact 180 or 181 and the contact bridge 184, the hardness of the contact 180 or 181 should be less than or equal to the hardness of the contact bridge 184. This is to ensure that not the contact bridge 184 but the contacts 180 and 181 wear out.

FIG. 10 shows a third embodiment of a contact bridge 184, as they are made FIG. 4 is known and a contact 180, the contact surface 300 is at least substantially planar. The contact bridge 184 moves as in the exemplary embodiment FIG. 8 corresponding. Ie. the edge 279 moves transversely to the marked longitudinal axis 312 of the contact pin 151. In this case, the edge scrapes 279 along the contact surface 300. Macroscopically, the contact surface between the contact bridge 184 and the contact surface 300 results in a line shape.

The embodiment according to FIG. 10 shows accordingly an electromagnetic switch 16 for a starting device 10 with two contacts 180, 181, which are electrically conductively connected to one another by a movable contact bridge 184, wherein at least one of the two contacts 180 or 181 preferably has a contact surface 300 fixedly connected to a contact pin 151 having. It is thereby provided that the contact surface 300 is at least substantially planar and an electrical contact between contact bridge 184 and contact 180, 181 giving edge 279th the contact bridge 184 is arranged so that, starting from the impact on the contact surface 300, it essentially allows line contact between contact 180, 181 and contact bridge 184

Based on FIG. 8 For example, a further definition of the manner in which the contact bridge 184 and the contact 180 or the contact 180 and the outer planar section 276 are oriented relative to one another can be given. Thus, between the outer planar portion 276 and the longitudinal axis 312 of the contact pin 151, an angle β may be indicated, for example lying in the plane passing through the longitudinal axis 312 and the central axis of the hole 226 (FIG. FIG. 4 This central axis of the hole 226 has the designation 315 and coincides with the axis of movement of the switching pin 177, see also FIG. 2 ,

According to this definition, an electromagnetic switch 16 is provided for a starting device 10, with two contacts 180 and 181, which are electrically conductively connected to each other by a movable contact bridge 184, wherein at least one of the two contacts 180 or 181 is preferably one with a contact pin 151, 150 fixed contact surface 300, wherein a contact 180 directed surface 318 of the contact bridge 184 and a longitudinal axis 312 of a contact pin 151 between them a directed to a central axis 315 of the switch 16 angle β include, which is greater than 90 °. This definition applies to the rest position or up to the position of the switching bridge 184, in which the contact bridge 184 the surface 300 is not or weakly touched with respect to the angle β is provided that this between 91 ° and 105 °, preferably by 95 ° is.

In FIG. 11 a fourth embodiment of a switch 16 is shown. Since the details of the switch after FIG. 11 from those of the switch according to FIG. 2 differ only in a few details, only these differences are discussed below.

While the contact bridge 184 according to FIG. 2 outer flat portions 276 and 273, which are inclined towards the contacts 180 and 181, respectively are bent, so the outer surface portions 276 and 273 of the contact bridge 184 are not inclined to the contacts 180 and 181, but inclined away from them. The inclination angle α accordingly decreases as compared with the embodiment FIG. 2 and the central area 270 have a different sign. The angle β is here defined as the angle which is arranged between the contact 180 directed surface 318 of the contact bridge 184 and a longitudinal axis 312 of a contact pin 151. The angle β is oriented in such a way that it lies in a plane that extends from the longitudinal axis 312 and the central axis 315 is formed. The angle β is directed radially outward and is greater than 90 °. With respect to the angle β is provided that this is between 91 ° and 120 ° Also, this size refers to the position of the contact bridge 184 in the rest position, or before it touches the contact surface 180. In the example according to FIG. 11 For example, the contacts 180 and 181 are designed such that they have an edge 320 which, from the moment in which the contact bridge 184 impinges on the contact surface 300, a relative movement transverse to the central axis 315 between contact bridge 184 and contact 180 and 181st causes. In this case, an edge 320 of the contact scrapes 180 or 181 on the contact bridge 184.

With respect to the angle α is provided that this has a value between -1 ° and -30 °. The choice of the angle is dependent on the coefficient of friction between the contact partners. Here, in the case where it is a high coefficient of friction, that the angle can be rather smaller, while at low coefficients of friction the angle is rather large.

The fifth embodiment according to FIG. 12 shows a schematic representation of two contact pins 150 and 151, which are oriented with their contact surfaces 300 to the outer planar portions 273 and 276. The length of the contact bridge 184 transverse to the central axis 315 is greater than the outermost distance of the two contact pins 151 and 150 to each other. Accordingly, the outer laminar portions 273 and 276 respectively do not scrape at one of their edges against the surfaces 300 of the contact pins 150 and 151. In this case, the contact bridge 184 switches against sharp edges 330 of the contacts 180 and 181, respectively

In a modification of the embodiment according to FIG. 12 switches the contact bridge 184 according to FIG. 13 not against outermost edges of the contact pins 151 and 150, but against angled edges 333rd

In FIG. 14 is a seventh embodiment of a pairing of contact bridge 184 and contact pins 151 and 150 shown. This seventh embodiment is a modification of the embodiment according to FIG. 13 and differs from this in that the contact bridge 184 no longer projects beyond the outermost contours of the two contact surfaces 300 or contact pins 151 and 150, respectively. Again, the contact bridge 184 switches against an angled edge 333 of the contact pins 150 and 151th

In FIG. 15 is another, eighth embodiment of a pairing of a contact bridge 184 and two contact pins 150 and 151 shown both contact pins 151 and 150 have in the region of their bolt heads 152 facing each other two bevels 336 on. Although these two bevels 336 are substantially directed to each other, but not parallel to each other. A contact bridge 184 is present whose length is shorter than the largest distance of the chamfers 336 to each other, but greater than the smallest distance between the two bevels 336 to each other. In this embodiment, an edge 279 of the outer laminar portions 273 and 276 scrapes on the bevels 336.

In FIG. 16 a contact bridge 184 is shown in a further alternative embodiment. This contact bridge also has a central areal section 270 and two outer areal sections 273 and 276, respectively. The central areal section 270 also has a hole 226 in its center. The edges 279 are in contrast to, for example, the embodiment of the FIG. 3 and FIG. 4 not round but straight. The outer planar sections 273 and 279 are analogous to the embodiment according to FIG. 3 and FIG. 4 also shown at an angle α to the central area 270 section.

Alternatively to the execution according to FIG. 16 can, as in FIG. 17 illustrated, the contact bridge 184 has two outer surface portions 273 and 276, in contrast to the embodiment of FIG FIG. 16 are slotted so that the respective planar sections are designed as two lugs 340. Instead of the designation flags, for example, the term sheet metal tabs would be suitable.

FIG. 18 shows a contact bridge 184, which is designed substantially rectangular. In turn, it has a central planar section 270 and two outer planar sections 276 and 273. Central in the planar section 270, in turn, a hole 226 is arranged. While in FIG. 18a a plan view can be seen is in FIG. 18b a sectional view of the contact bridge 184 shown. This sectional view shows the bending of the outer flat sections 273 and 276 by the angle α. To influence or increase the flexibility of the outer planar sections 273 and 276, these are connected via notches 350 with the central planar section 270. The notches may, as here in the example, be arranged on both sides of the surface of the contact bridge 184, but also, if appropriate, alternatively on one side. These notches 350 are here designed as semicircular corrugations to reduce the cross section and reduce the flexural rigidity of the contact bridge 184

As shown in FIGS. 19a and 19b a further contact bridge 184 is shown in a plan view and a sectional view. The constrictions for reducing the cross section or reducing the flexural rigidity of the contact bridge 184 need not, as in accordance with FIG. 18 represented, are introduced at the outer contour. It can also recesses in the preferably rectangular shaped contact bridge 184 are introduced. In FIG. 19 For example, two circular recesses 353 are shown, which reduce the cross section. The recesses may have any shape, for. B. be executed rectangular or rounded.

In the FIG. 20 a contact bridge 184 is shown in longitudinal section. This contact plate in turn has a central areal section 270 and two outer areal sections 273 and 276. The central sheet-like section 270 in turn has a hole 226, as in the previous embodiments for Contact bridges 184 also have. This contact bridge 184 consists of several layers. A first layer is a carrier layer 400 and a second layer attached to this carrier layer 400 is a contact layer 403. In the case of the contact bridge 184 embodied here, the properties are optimized by forming the contact bridge 184 of multiple layers. Thus, the first layer, namely the carrier layer 400 , favorable features as a holding, stability and elasticity giving element. By contrast, the contact layer 403 has optimized properties with regard to the contact between contact bridge 184 and contact 180 or 181. It is envisaged that the carrier layer 400 is made of a copper or a silver alloy or steel or bronze or brass. The contact layer 403 is provided to be made of a copper, tin, gold or silver alloy or a metal-metal oxide composite consists

For the contacts 180 and 183 of the contact pins 151 and 150 should generally apply that these also consist of electro-copper and have a hardness between 100 and 130 HV10.

For example, by the shape of the contact bridge 184 FIG. 4 ( "Necking"), FIG. 16, FIG. 17, FIG. 18 and FIG. 19 the spring stiffness is reduced compared to previously known contact bridges. This leads to a greater elastic deformation when connecting the contacts 180 or 181 with the already described advantages of increased damping and the destruction of a resulting oxide layer.

With respect to the edges 279 and 320, it is provided that this has a radius of <0.3 mm. This results in a "chisel effect" so that edges 279 and 320, respectively, remove interfering layers at the opposite contact. Contacting properties are thereby considerably improved. In the area of the edges 279 and 320, there is preferably an area-wise or linearly very small cohesive connection due to Einschalbichtbögen. By tearing open these cohesive connections, the respective edge 279 or 320 experiences an ever new sharpening, whereby even after repeated switching characteristics or point contact between edge and mating contact remains edges 279 and 320 moreover have the advantage that ice layers formed by possible atmospheric moisture in the switch are broken on the contacts 180 or 181.

With regard to the material thickness of the contact bridge 184, it is generally provided that the corresponding metal sheet preferably has a thickness of between 1 and 4 mm.

Furthermore, a method for switching the electromagnetic switch 16 is provided, wherein it has two contacts 180 and 181, which are connected by a movable contact bridge 184. When contacting the contact bridge 184 with at least one of the two contacts 180 and 181, a scraping movement between the contact bridge 184 and the contact surface 300 of the contact 181 or 180 acts. Either slides the contact bridge with its surface in the form of an edge 279 on the contact surface 300 of Contact 180 or 181, or the contact surface 300 of the contact 180 or 181 with its surface shape of an edge 320 slides over the contact bridge 184. A possible cohesive connection between the contact bridge 184 and the contacts 180 and 181 should in the case of release by a thrust load in the cohesive connection (welding) are solved.

The edge 279 serves to scrape on the surface of the contacts 180 and 181, thereby creating friction and ultimately converting energy. The energy to be converted is the kinetic energy of the contact bridge 184 and the moving during the switching operation parts, such as the switching pin 177, the snap sleeve 241, compression spring 238, guide collar 232, collar 223. This kinetic energy is generated by the friction of the contact bridge 184 on the contacts 180 and 181 reduce the kinetic energy so far that a rebound of the contact bridge 184 substantially no longer occurs and thereby the tendency to form arcs between the contacts 180 and 181 and the contact bridge 184 is at least greatly reduced.

FIG. 21 shows a side or sectional view of the contact bridge 184, which makes an electrical connection with the contact 180 of the bolt 151. As can be seen there, the contact 180 or its contact surface 300 has a corrugation which is an annular corrugation 310. This contact surface 300 or its corrugation is such that, in the cross-sectional view results in a wavy contour. This corrugated contour can be, for example, a sinusoidal profile or a similar profile with wave shape, ie one with "valleys and mountains", see also FIG. 6 , The corrugation shown here is an annular corrugation 310, ie the corrugated contour 303 or its "peaks and valleys" are in the example oriented coaxially about the center line 306 of the bolt 151. It is envisaged that the contact bridge 184 slides or rubs along an edge 420 of the wave-shaped contour 303 when switching or contacting with its outer flat section 276.

In Figure 22A a diagram is shown in which, depending on a constriction ratio and a lever arm ratio, the bending stress in the constriction region is shown. The constriction area is the area of the contact bridge 184, which corresponds to the in FIG. 5 shown waisted cross-section 293 corresponds. In principle, this applies to all cross-section reduced contact bridges 184, as for example in the FIGS. 16 to 19 is shown. The three curves K25, K50 and K75 shown there represent different parameters. The curve K25 shows a lever arm ratio of 25%, K50 shows a lever arm ratio of 50%, K75 shows a lever arm ratio of 75%. "Lever ratio" means that with reference to Figure 22B a ratio of LH / L = ¼ = 25%. The greater the lever arm ratio, the greater the stress S in the cross section 293 under the same loading with a force. Furthermore, the necking ratio V is taken into account. V is the quotient of the width BE to the width B184. In order to avoid or prevent bouncing and to convert it into friction, sliding movement, it is provided that the bending stress S in the cross section 293 is greater than 20 N / mm 2. Furthermore, the bending stress S should be less than 100N / mm 2. It is desirable for the necking ratio V to be less than or equal to 75%, preferably greater than 25%. A ratio of between 70% and 35% has proven to be particularly favorable.

Claims (5)

1. Electromagnetic switch (16) for a starting device (10), comprising two contacts (180, 181) which are electrically conductively connected to one another by a movable contact link (184), wherein at least one of the two contacts (180, 181) has a contact surface (300) - which is preferably fixedly connected to a contact pin (150, 151), characterized in that the contact surface (300) has a fluting in the form of an annular fluting (310), and the contact link (184) slides or rubs by way of an outer flat section (276) along a flank (420) of the undulating contour (303) when switching or when contact is made.
2. Electromagnetic switch according to Claim 1, characterized in that the contact link (184) comprises a central flat section (270) which is oriented perpendicular to the switching pin (177) and which is adjoined by at least one outer flat section (273; 276) in a manner pointing away from the switching pin (177), wherein at least one outer flat section (273, 276) is inclined or bent in the direction towards the contacts (180, 181).
3. Electromagnetic switch according to either of the preceding claims, characterized in that the contact link (184) is guided in a bearing by means of the switching pin (177), and the contact link (184) has a region with the greatest cross section (290) between the switching pin (177) and an edge (279), and a region with a reduced cross section (293) between the region with the greatest cross section (290) and the switching pin (177).
4. Electromagnetic switch (16) according to Claim 2, characterized in that there is a constriction between the central flat section (270) and the outer flat section (276).
5. Electromagnetic switch (16) according to one of the preceding claims, characterized in that the two outer flat sections (273, 276) have an approximately circular contour.

Images