WO2021001465A1

WO2021001465A1 - Electrical contact system for a switching device

Info

Publication number: WO2021001465A1
Application number: PCT/EP2020/068605
Authority: WO
Inventors: Marcus Herrmann; Erik Herzog; Niels Goller
Original assignee: Johnson Electric Germany GmbH and Co KG
Current assignee: Johnson Electric Germany GmbH and Co KG
Priority date: 2019-07-02
Filing date: 2020-07-02
Publication date: 2021-01-07
Anticipated expiration: 2022-01-02
Also published as: DE102019117804B4; EP3981019B1; CN114041197B; CN114041197A; EP3981019A1; DE102019117804A1

Abstract

Electrical contact system (2) for a switching device (1) includes at least one pair of contacts (3) having a fixed contact piece (4) and a contact piece (5). The contact piece (5) is coupled to a slide (15). A planar contact piece carrier (7) extends in the longitudinal section thereof and is attached at the first end (11) to a second busbar (13). A second end (12) of the contact piece carrier (7) is coupled to the slide (5). A spring element (18) having a first spring arm section (22) and a second spring arm section (23) and a pressure region (24) arranged therebetween in the area of the movable contact piece (5). The first spring arm section (22) is attached to the second busbar (13) at the first end (11). The second spring arm section (23) is also coupled at the free end (21) thereof to the slide (15).

Description

Electrical contact system for a switching device

The present invention relates to an electrical contact system for a switching device, wherein the switching equipment for which the invention can be used includes relays, switches, contactors and circuit breakers.

Switching equipment such as relays, switches, contactors and circuit breakers should have the following properties: low electrical resistance between the connection terminals, which allows high efficiency to be achieved due to a low dissipation loss, as well as safety of the device during operation, in particular with regard to heating up and fire protection; a long service life, which means as large a number of switching operations under load as possible; and a safeguard against contacts sticking to one another as a result of a high short-circuit current, for example in the event of an electrical fault.

In conventional switching equipment, spring elements ensure fast lifting of the movable contact piece away from the fixed contact piece when the contact is released, which reduces wear on the contact pieces.

Particularly in relays, spring elements of this kind are typically produced from steel and riveted to the movable contact piece. The disadvantages associated these steel elements that are riveted to the movable contact are due to the high load and low flexibility, which in turn facilitates only minimal tolerance compensation.

Spring elements produced from steel that are attached to a magnetic actuator of the switching device or a mechanical coupling element, referred to as a slide in the following, are also known. The magnetic actuator generates and the slide then transfers the force required to open or close the contacts. A spring can be used to release two or more contacts at the same time here. However, the attachment of the spring elements to the actuator or to the slide has the disadvantage that a device constructed in this way is scarcely suitable for delayed opening or closing of at least two pair of contacts. This kind of time-delayed opening or closing of the contacts is also referred to as the lead-lag switching characteristic.

Another version known from the state of the art comprises a spring element that is integrated into a current path of the contact piece carrier for the movable contact piece. However, this would lead to an even greater mechanical load than the aforementioned direct attachment of the spring element to the movable contact piece. In addition to this, it has the disadvantage that the spring heats up, which can lead to deformation of the slide and thereby shorten the service life of the contact system. Also, roll-off movements of the contacts are restricted as a result of the contact piece carrier being deformed during a short-circuit due to the conditions listed in the following. In the event that the spring element is attached to the movable contact piece, for example by being riveted on, a high degree of stiffness leads to reduced flexibility of the spring element and thereby restricts the roll-off movements of the contacts. Insofar as the spring is integrated in the contact piece carrier of the movable contact piece, the roll-off movements are restricted due to reduced flexibility of the current path of the contact piece carrier of the movable contact piece.

The underlying object of the invention is defined as provision of a space- saving electrical contact system that can be affordably produced, delivers high performance, has a long service life, and permits both secure absorption and transfer of the short-circuit forces.

The object of the invention is resolved using an electrical contact system and leads to corresponding advantages in a switching device provided therewith. Further embodiments are provided.

An electrical contact system constructed according to the invention that is suitable for a switching device, such as a relay, having at least one pair of contacts having one fixed contact piece, which is attached to a first busbar with a fixed location relative to the housing of the switching device, and one contact piece that is movable relative to the fixed contact piece wherein the contact piece is coupled to a slide and is movable by the slide in such a manner that the pair of contacts can be opened and closed relative to each other; one planar contact piece carrier to which the movable contact piece is attached, wherein the contact piece carrier extends in its longitudinal section along its longitudinal axis from a first end up to a second end, wherein the first end is attached to a second busbar, whose position is fixed relative to the housing of the switching device wherein the second end of the contact piece carrier is coupled to the slide; one spring element having a first spring arm section and a second spring arm section and a pressure region arranged therebetween in the area of the movable contact piece, wherein the first spring arm section is attached to the second busbar at the first end of the contact piece carrier and wherein the second spring arm section is also coupled at the free end thereof to the slide in such a manner that the spring element exerts a contact force on the movable contact piece via the pressure region. The spring element has a lower electrical conductivity than copper or has an electrically insulating coating, for example an insulating varnish. An electrically insulating spring element can be useful if a significant proportion of the electrical current flows through the spring element, since this allows the current in the contact carrier, which is designed in a layered construction, to be reduced. This reduces the repulsion forces, called "blow off force," in the layered contact carrier in a short circuit test.

Furthermore, the spring element is attached to the second busbar and has at least one spring arm having a first spring arm section and a second spring arm section, wherein the first spring arm section stretches from an attachment section up to a position with at least one pressure region and the second spring arm section stretches from this position up to a free end of the spring arm. This enables a defined contact force even after the contact carrier has overheated and ensures reliable maintenance of the relay function.

If the planar contact piece carrier is substantially straight in the longitudinal section thereof along the longitudinal axis thereof from a first end to a second end, the tolerance problem can be brought under control in a technically elegant manner.

According to the invention, the at least one pressure region is positioned in such a way that a direct or indirect force-locking connection between the pressure region and the movable contact piece can be generated via a preload of the spring element, in turn allowing a force to be applied to the pair of contacts.

When the pair of contacts is electrically opened, the spring element remains preloaded and exerts a contact force on the contact via the pressure region. It is advantageous that this contact force is immediately effective when the contact is closed, compressing the contacts and minimizing contact bounce. Optionally, the contact piece carrier of the movable contact can be positioned in such a manner that it increases the contact force when the contacts are closed and further reduces bouncing and contact resistance.

In order to be able to benefit from attraction or repulsion forces in conductors through which current flows, the contact piece carrier is ideally attached to the second busbar in such a manner that it forms a V-shape together with the second busbar in longitudinal section, in other words, along the longitudinal axis.

The conceptual design according to the invention focuses on the use of a spring element with low conductivity that is attached solely to the same busbar to which the contact piece carrier for the movable contact piece is also attached. A spring element of this kind combines various beneficial mechanisms of action with one another. The spring element is preferably designed in a lamella-shaped or a strip-shaped. In one embodiment, the spring element is a leaf spring.

The spring element can be produced from a paramagnetic or optionally a diamagnetic material. The spring element should preferably be produced from a material with paramagnetic properties. Particularly preferred materials here are stainless steel or stainless steel alloys. The material of the spring element must definitely be less conductive than the material of the fixed-location busbar and of the contact piece carrier, so that as little current as possible flows through the spring element. The difference in conductivity between steel and copper is a factor of between 6 and 7. For example, if the fixed-location busbar and the contact carriers were produced from aluminum instead of copper, but the spring was still produced from steel, the factors between the conductivities would be around, which is also still adequate. A sufficiently low conductivity for the spring element is provided with all materials that are less conductive than steel. One beneficial effect is based on application of a force to pairs of contacts that is generated by a preload of the spring element and presses the contact pieces together. This produces the pressure regions, so-called a-spots, at the interface between the contact pieces, wherein these pressure regions facilitate the flow of current. The greater the pressure force here, the greater the size (area) of the pressure region available for the flow of current and also the lower the electrical resistance at the pressure region.

Another improvement over the state of the art is achieved according to a preferred embodiment of the invention, with which the contact system comprises multiple pairs of contacts, by generating the contact force separately for each of the pairs of separable contact contacts. Multiple pairs of contacts can be connected in parallel here in order to keep the electrical resistance constantly low throughout the service life, even if one pair of contacts bums out. Multiple movable contact pieces can be arranged on the contact piece carrier transversely to its longitudinal axis or one after the other in the direction of the longitudinal axis or transversely to the longitudinal axis, yet offset in the direction of the longitudinal axis. As already mentioned above, the geometric form of a pair of contacts that gets burned out is changed, for example due to the burning itself or, particularly with bimetal contact rivets, due to delamination. The change of shape causes a change in the very important spring preload and thereby also the contact force. To ensure that pairs of contacts that have not been burned are not changed by pairs of contacts that have been burned, the force is generated separately for each pair of contacts. This is implemented by the beneficial design of the spring element as a leaf spring with separate spring arms for each pair of contacts. This leads to a low electrical resistance, even when using multiple pairs of contacts, one of which suffers burning.

Another aspect of the invention concerns a switching device, such as a relay, that encompasses the electrical contact system according to the invention. A corresponding switching device also encompasses an exciter coil and a solenoid classed as an armature, that has an operative connection to the slide as a mechanical coupling element. A force can be generated by the exciter coil here due to the magnetic field it creates that can then be applied to the contact system via the armature and the mechanical coupling element, so that the contact system can be switched by the exciter coil.

Another beneficial mechanism of action of the spring element is based on generating a force on the armature/solenoid, which then supports this opening process, so that the contact(s) can be opened as quickly as possible. The greater the preload force of the spring element, the faster the opening speed of the contacts and the less severe the contact bum (erosion) as a result of the opening arc when disconnecting the electrical load. The less severe the contact bum, the more switching operations can be completed, which in turn increases the service life of the corresponding switching device.

The low spring constant of the spring element is particularly beneficial here. The spring constant generally states the ratio of the force acting on the spring to extend the spring. Due to the way the system works, a significant portion of the spring force is applied to the solenoid after opening the contacts. Only a fraction of the contact force is applied, which is the result of the preload of the spring element (leaf spring) between the movable contact piece and the busbar that is connected to the movable contact piece carrier. This force component counteracts the opening movement and increases as the contacts are opened wider, since the spring section is increasingly preloaded with the opening movement. The low spring constant means that the increasing preload distance only leads to a minimal increase in force, so that the solenoid is only slowed down very slightly in the opening movement. This results in a faster opening movement of the contacts and thereby a longer service life of the device.

Another advantage is based on the high thermal stability of the spring material. The contact system heats up during the switching operation. The spring material has corresponding thermal stability, which secures the mechanical properties at increased temperatures. Another beneficial effect is based on the fact that the spring material has either no or only low electrical conductivity and, in the case of stainless steel, for example has paramagnetic behavior. The relationship between low conductivity or paramagnetic properties of the spring element and the beneficial effect, namely prevention of contact welding, is explained in greater detail in the following.

There are two key effects that prevent contact welding in the event of a short-circuit. One of these effects focuses on a relative movement between the switching contact pieces while current is flowing through the contact pieces. Another effect focuses on application of an increased contact force in order to increase the contact surface. Firstly, this lowers the current density in the pressure region between the contact pieces. Secondly, the constriction resistance (Holm's force) that occurs between the contacts as a result of the current flow is compensated. The constriction resistance (Holm's force) always acts in the direction of contact opening and would, without a corresponding counterforce, cause the contacts to open in the event of a short-circuit fault. The forces required to achieve these effects are generated by magnetic fields, wherein the magnetic fields result from the short-circuit current itself. These effects should not be influenced by the spring element. Firstly, the low electrical conductivity prevents a high short-circuit current from flowing through the spring element, so that no relevant magnetic field forms around the spring element. Secondly, application of magnetic reluctance forces on the spring or surrounding components due to magnetic fields around the current path can be prevented by paramagnetic properties of the spring element. This makes a valuable contribution to preventing the contacts from sticking together due to the actual mode of action, namely the relative movement between the switching contact pieces, not being influenced by the spring element.

Another beneficial mechanism of action is achieved through generation of an orthogonal force action on the pressure region by the spring element. A force-locking connection is in place between the switching electrical contact and the spring element due to the spring preload. However, the force action does not contain any torque component here. The spring element only rests with its pressure region(s) on the reverse side of the movable contact piece or on the sections of the contact piece carrier adjacent to the movable contact piece and is not attached to it. As such, a compressive force, also referred to as normal force in the following, can only be transferred orthogonally from the spring element to the contact. The transmission of a torque or significant lateral force is not possible or is thereby prevented. This leads to a situation in which the described relative movement transverse to the contact surface is not impaired in the event of a short-circuit. This results in greater safety against the contacts sticking together, as the modes of action applied are not influenced.

In a particularly preferred embodiment of the invention, the at least one movable contact piece with a projection provided on its reverse side, also referred to as a rivet collar, stretches through a corresponding mounting hole in the contact piece carrier. This makes it possible for the spring arm of the spring element to rest directly on the projection of the contact piece, the rivet collar, with a pressure region and apply pressure. However, the at least one spring arm should preferably have in the area of the pressure regions a widened, ring-shaped section that is arranged transversely to the longitudinal axis of the contact piece carrier with a central recess that is positioned in such a way that it rests on the contact piece carrier in preloaded state and encircles the projection present on the reverse side of the movable contact piece. In this embodiment, the at least one spring arm preferably has two pressure regions in opposing positions of the widened ring-shaped section.

It is also possible to use contact pieces without a rivet collar. These can be soldered or welded onto the contact piece carrier, so no mounting hole is required. In this case, the spring arm of the spring element could rest or press with just one pressure region directly on the contact piece carrier on the reverse side of the attachment location of the movable contact piece.

In an embodiment preferred in terms of manufacture and function, the slide has a recess into which the second end of the contact piece carrier and the free end of the second spring arm section of the spring element project.

Further details, features and benefits of embodiments of the invention result from the following description of specimen embodiments with reference to the accompanying drawings.

The invention shall be explained in detail in one exemplary embodiment by reference to Figures 1 to 5.

Fig. 1: A sectional view of an electrical contact system with a spring element in a relay as a switching device;

Fig. 2: A side view of a part of the electrical contact system;

Fig. 3: A spring element with two spring arms;

Fig. 4: A perspective view an electrical contact system with two contacts and

Fig. 5: A frontal view of a part of an electrical contact system with two contacts of different sizes.

Fig. 1 shows a schematic sectional view of a relay 1 as an example of a switching device 1, in which an electrical contact system 2 with the characteristics of the present invention is applied. The electrical contact system 2 encompasses at least one contact 3, which is formed by a pair of contact pieces 4, 5. Here, the at least one contact comprises a fixed contact piece 4, which is attached to a first busbar 6 with a fixed location relative to the housing 33 of the switching device, and one contact piece 5 that is movable relative to the fixed contact piece 4 for the switching function, wherein the contact pieces of the at least one contact are positioned relative to one another in such a way that the movable contact piece 5 can be pressed onto the fixed contact piece 4 using a contact force.

In addition to this, the electrical contact system 2 encompasses a planar contact piece carrier 7 for at least one movable contact piece 5. This contact piece carrier 7 can have spring characteristics and is therefore often also referred to as a contact spring.

As shown in Fig. 1, the planar contact piece carrier 7 is produced from two current paths positioned above one another 8, 9 and is essentially constructed straight in its longitudinal section along its longitudinal axis from a first end 11 up to a second end 12. The contact piece carrier 7 is attached by its first end 11 to a second busbar 13 with a fixed position relative to the housing 33 of the switching device, preferably riveted on, and forms a V-shape together with this in its longitudinal section. The at least one movable contact piece 5 is attached in the area of the second, free end of the contact piece carrier 7. In the embodiment shown, the contact piece carrier 7 comprises a first, straight current path 8 and a second current path 9, wherein the second current path 9 is also constructed straight with the exception of one curve section 10 that projects outwards from its plane and stretches transversely to the longitudinal axis across the entire width of the contact piece carrier. The curve section 10 is located near the first end 11 of the contact piece carrier 7, with which the contact piece carrier 7 is attached to the second busbar 13.

The relay 1 also has a solenoid actuator for moving the contact piece carrier 7 into the respective relay position. The solenoid actuator has a magnetic coil, a permanent magnet and an armature 14, which is held pivotably on the magnetic coil between two switching positions. The armature 14 is connected to a mechanical coupling element 15 in the form of a slide 15 in such a way that the slide 15 can be raised and lowered by the swivel movement of the armature 14. The armature 14 can therefore also be classed as a lifting magnet or solenoid. The armature 14 is held both from above and below in the direction of motion of the lifting and lowering movement of the slide 15 by the slide 15 on its lower end section 16. In the area of the free end 12 of the contact piece carrier 7, the upper end 17 of the slide 15 rests on its underside. The slide 15, which is connected to an armature 14, can then transfer a force generated by the magnetic field of an exciter coil in a relay 1 to the contact piece carrier 7 with the at least one attached movable contact piece 5, so that the contact between the fixed contact piece 4 and the movable contact piece 5 can be opened or switched by the exciter coil.

As a characteristic key to the invention, the contact system 2 encompasses a spring element 18 with low conductivity that is preferably produced from stainless steel or a stainless steel alloy. This spring element 18 is attached to the second busbar 13, to which the contact piece carrier 7 for the movable contact piece 4 is also attached. The spring element 18 encompasses an attachment section 19, with which the spring element 18 is attached (preferably riveted) to the second busbar 13. Starting from the attachment section 19, the spring element 18 has at least one spring arm 20, which runs from the attachment section 19 up to a free end 21 of the spring element 18. The at least one spring arm 20 can be split into two different spring arm sections 22, 23. A first spring arm section 22 runs from the attachment section 19 up to a pressure region 24 with which the spring element 18 only rests on the reverse side of the movable contact piece 5 or on the section of the contact piece carrier 7 adjacent to the reverse side of the movable contact piece 5, but is not attached to the contact piece 5 or the contact piece carrier 7. Starting from the pressure region 24, the second spring arm section 23 stretches up to the free end 21 of the spring arm 20. The distance between the contact piece carrier 7 and the second spring arm section 23 is increased here, starting from the pressure region 24 at which the spring element still rests on the movable contact piece 5 or the contact piece carrier 7 and continuing up to the end 21 of the spring arm 20. This means that the two different spring arm sections 22, 23 together form a V-shape.

A spring element 18 produced in this way combines various beneficial mechanisms of action with one another. Due to a preload of the spring element 18, schematically depicted as a continuous line by the second spring arm section 23, a force-locking connection 25 is therefore in place between the pressure region 24 and the movable contact piece 5 and consequently a force is applied to the contact 3 which presses the contact pieces 4, 5 together and is indicated by the arrow 26. The force 26 applied to the contact 3 produces the contact points, so-called a-spots, at the interface between the contact pieces 4, 5, wherein these contact points facilitate the flow of current. The greater the contact force here, the greater the size (area) of the contact point available for the flow of current, indicated by the arrow 27, and also the lower the electrical resistance at the contact point.

Another beneficial mechanism of action of the spring element 18 is based on generating a force on the armature/solenoid 14, wherein this force, which is indicated by an arrow in Fig.1, then supports the armature/solenoid 14 during the opening process. This force also ensures that the contact(s) 3 can be opened as quickly as possible. The greater the preload force of the spring element 18, the faster the opening speed of the contacts 3.

Due to the way the system works, a significant portion of the spring force is applied to the armature/solenoid 14 after opening the contacts 3. Although the spring arm section 23 is preloaded at all times, a mechanical contact is however established between the second end 12 of the contact piece carrier and the slide 15 when opening the electrical contacts. This shifts the flow of force. The preload force of the spring element 18 is absorbed fully in the slide 15 and no longer dissipated via the armature 14. The resulting force of the spring preload 28 on the armature 14 then equals zero when opening the contacts. This condition is schematically shown in Fig. 1 in the form of a broken line that depicts the second spring arm section 23‘. Only a fraction of the previously applied contact force is applied, which is the result of the preload of the first spring arm section 22 that acts as a spring element between the movable contact piece 5 and the busbar 13 that is connected to the movable contact piece carrier 7. This force component counteracts the opening movement of the movable contact piece 5 and increases as the contacts are opened wider, since the spring arm section 22 is increasingly preloaded with the opening movement. The low spring constant means that the increasing preload distance only leads to a minimal increase in force, so that the solenoid 14 is only slowed down very slightly in its opening movement. This results in a faster opening movement of the contacts 3 and thereby a longer service life of the device.

When the pair of contacts 3 is electrically open, the spring element 18 remains preloaded and exerts a contact force 26 on the contact via the pressure region 24. It is advantageous that this contact force is immediately effective when the contact is closed, compressing the contacts 3 and minimizing the bouncing of the contacts 3.

In addition, a beneficial mechanism of action is achieved through generation of an orthogonal force action on the pressure region by the spring element 18. A force-locking connection is in place between the switching electrical contact 3 and the spring element 18 due to the spring preload. However, the force action does not contain any torque component here. The spring element 18 only rests with its pressure region 24 on the reverse side of the movable contact piece 5 or on the section of the contact piece carrier 7 that is adjacent to the reverse side of the movable contact piece 5 and is not attached to it. As such, a compressive force can only be transferred orthogonally from the spring element 18 to the contact 3. The transmission of a torque or significant lateral force is not possible or is thereby prevented. This means that a relative movement transverse to the contact surface is not impaired in the event of a short-circuit. This provides greater safety against the contacts sticking together.

In an embodiment preferred in terms of manufacture and function, the slide 15 has a recess 35 into which the second end 12 of the contact piece carrier 7 and the free end 21 of the second spring arm section 23 of the spring element 18 project.

Fig. 2 shows a side view of a part of the electrical contact system 2. This part of the electrical contact system 2 encompasses the planar contact piece carrier 7 for at least one movable contact piece 5. As shown in Fig. 2, it comprises two current paths 8, 9 positioned above one another and is essentially constructed straight in its longitudinal section along its longitudinal axis from a first end 11 up to a second end 12. The contact piece carrier 7 is attached to the second busbar 13 by its first end 11 with a rivet joint and forms a V-shape in its longitudinal section together with the busbar 13. The at least one movable contact piece 5 is attached in the area of the second, free end 12 of the contact piece carrier 7. The contact piece carrier 7 comprises a first, straight current path 8 and a second current path 9, wherein the second current path 9 is also constructed straight with the exception of one curve section 10 that projects outwards and stretches transversely to the longitudinal axis in the section adjacent to the first end across the entire width of the contact piece carrier. In addition to the contact piece carrier 7, the spring element 18 is also attached to the second busbar 13. The spring element 18 encompasses an attachment section 19, with which the spring element 18 is attached to the second busbar 13 via a rivet joint. Starting from the attachment section 19, the spring element 18 has the spring arm 20, which runs from the attachment section 19 up to the free end 21 of the spring element 18. The spring arm 20 can be split into two different spring arm sections 22, 23‘. A first spring arm section 22 runs from the attachment section 19 up to a pressure region 24 with which the spring element 18 only rests on the reverse side of the movable contact piece 5 or on the section of the contact piece carrier 7 adjacent to the reverse side of the movable contact piece 5, but is not attached to the contact piece 5 or the contact piece carrier 7. Starting from the pressure region 24, the second spring arm section 23‘ stretches up to the free end 21 of the spring arm 20. The two spring arm sections 22, 23‘ together form a V-shape. Fig. 3 shows a spring element 18 that is constructed according to a beneficial embodiment of the invention. This embodiment concerns multi-contact systems, on which at least two movable contact pieces are arranged and attached transversely to the longitudinal axis 34 of the contact piece carrier in the area of the second, free end of the contact piece carrier. Multiple pairs of contacts can then be switched in parallel. For this case, the spring element 18 can be constructed as a leaf spring with an attachment section 19 and with separate spring arms 20a, 20b that start from this attachment section 19. In the area of the pressure regions 24a; 24b, the spring arms 20a; 20b each has a widened section 29a; 29b that is also referred to as a spring tongue 29a; 29b in the following. Each spring tongue 29a; 29b has a central recess 30a; 30b, essentially making it ring-shaped. Each spring arm 20a; 20b has two pressure regions 24a; 24b in opposing positions of the ring-shaped spring tongue 29a; 29b.

Fig. 4 shows a perspective view an electrical contact system 2 with two pair of contacts 3a, 3b, in which the spring element 18 shown in Fig. 3 is used. A two-contact system is produced here, wherein in the area of the second, free end 12 of the contact piece carrier 7 two movable contact pieces 5a, 5b are arranged and attached transversely to the longitudinal axis of the contact piece carrier and each form a pair of contacts 3 a; 3b with a corresponding fixed contact piece 4a; 4b. In the embodiment shown, the contact piece carrier 7 is split into two parallel legs 3 la, 3 lb at least in the end section that carries the contact pieces. The recesses 30a, 30b ensure that the pressure regions 24a, 24b of the spring tongues 29a, 29b do not rest directly on the reverse sides of the movable contact piece 5a; 5b, but rather on the adjacent section of the contact piece carrier 7, as the projections 32a; 32b formed by the reverse sides of the movable contact pieces 5a, 5b, which are guided through the contact piece carrier 7 through corresponding holes in the contact piece carrier 7 and project from the contact piece carrier 7, are located inside the recesses 30a, 30b.

Fig. 5 shows a frontal view of a part of an electrical contact system 2 with two contacts of different size. The different sizes of the movable contact pieces 5a, 5b and of the their projections that are formed on the reverse side 32a, 32b also require spring tongues of different sizes 29a, 29b and recesses of different sizes 30a, 30b in the spring arms 20a, 20b.

List of reference symbols

1 Relay, switching device

2 Electrical contact system

3 Contact, pair of contacts

3 a Contact, pair of contacts

3b Contact, pair of contacts

4 Contact piece, fixed contact piece

4a Contact piece, fixed contact piece

4b Contact piece, fixed contact piece

5 Contact piece, movable contact piece

5 a Contact piece, movable contact piece

5b Contact piece, movable contact piece

6 First busbar

7 Contact piece carrier of the movable contact piece

8 Current path of the contact piece carrier of the movable contact piece

9 Current path of the contact piece carrier of the movable contact piece

10 Curve section

11 First end of the contact piece carrier of the movable contact piece

12 Second end of the contact piece carrier Second busbar

Armature, solenoid

Mechanical coupling element, slide

Lower end section of the slide

Upper end of the slide

Spring element

Attachment section of the spring element

Spring arm

a First spring arm (with two-contact system)

b First spring arm (with two-contact system)

Free end of the spring element

First spring arm section

Second spring arm section with preloaded spring element ‘ Second spring arm section with non-preloaded spring element

Pressure region

a Pressure region

b Pressure region

Force-locking connection

Force of the spring element on the contact, contact force Flow of current

8 Force of the spring element on the armature

a First spring tongue, widened section (with two-contact system) b Second spring tongue, widened section (with two-contact system) a Recess in the first spring tongue

b Recess in the second spring tongue

1a First leg of the contact piece carrier (with two-contact system) lb Second leg of the contact piece carrier (with two-contact system) a Projection on the reverse side of a first movable contact b Projection on the reverse side of a second movable contact

Housing

Longitudinal axis of the contact piece carrier

Recess in the slide

Claims

1: An electrical contact system (2) for a switching device (1), comprising:

at least one pair of contacts (3) having one fixed contact piece (4), which is attached to a first busbar (6) with a fixed location relative to the housing (33) of the switching device, and one contact piece (5) that is movable relative to the fixed contact piece (4) wherein the contact piece (5) is coupled to a slide (15) and is movable by the slide (15) in such a manner that the pair of contacts (3) are opened and closed relative to one another;

one planar contact piece carrier (7), to which the movable contact piece (5) is attached, wherein the contact piece carrier (7) extends in the longitudinal section thereof along the longitudinal axis (34) thereof from a first end (11) to a second end (12), wherein the first end (11) is attached to a second busbar (13), whose position is fixed relative to the housing (33) of the switching device, wherein the second end (12) of the contact piece carrier (7) is coupled to the slide (15); and

a spring element (18) having a first spring arm section (22) and a second spring arm section (23) and a pressure region (24) arranged between them in the area of the movable contact piece (5);

characterized in that the first spring arm section (22) is attached to the second busbar (13) at the first end (11) of the contact piece carrier (7), and the second spring arm section (23) is coupled at the free end (21) thereof to the slide (15) in such a manner that the spring element (18) exerts a contact force (26) on the movable contact piece (5) via the pressure region (24).

2. The electrical contact system (2) according to claim 1, characterized in that the spring element (18) presses on the movable contact piece (5) via the pressure region (24) even when the pair of contacts (3) is electrically opened.

3. The electrical contact system (2) according to claim 1, characterized in that the spring element (18) is bent in the area of the pressure region (24) in such a manner that it has a V-shaped cross-section in longitudinal section at least in the area of the pressure region (24).

4. The electrical contact system (2) according to claim 1 or 2, characterized in that the spring element (18) has a lower electrical conductivity than copper or has an electrically insulating coating.

5. The electrical contact system (2) according to any of the preceding claims, characterized in that the spring element (18) is produced from a paramagnetic or alternatively a diamagnetic material.

6. The electrical contact system (2) according to claim 5, characterized in that the spring element (18) is produced from stainless steel or a stainless steel alloy.

7. The electrical contact system (2) according to any of the preceding claims, characterized in that the contact piece carrier (7) is attached to the second busbar (13) in such a manner that together with the latter it forms a V-shape or a U-shape in longitudinal section along the longitudinal axis.

8. The electrical contact system (2) according to any of the preceding claims, characterized in that the contact system (2) encompasses multiple pairs of contacts (3a, 3b), wherein multiple movable contact pieces (5a, 5b) are arranged on the contact piece carrier (7) transversely to its longitudinal axis or one after the other in the direction of the longitudinal axis or transversely to the longitudinal axis, but offset in the direction of the longitudinal axis.

9. The electrical contact system (2) according to claim 8, characterized in that the spring element (18) is constructed as a leaf spring.

10. The electrical contact system (2) according to claim 8, characterized in that the spring element (18) is constructed having separate spring arms (20a, 20b) for each pair of contacts (3a, 3b).

11. The electrical contact system (2) according to any of the preceding claims, characterized in that the at least one movable contact piece (5a; 5b) stretches through a corresponding mounting hole in the contact piece carrier (7) with a projection produced on its reverse side and that the at least one spring arm (20a; 20b) has a widened ring-shaped section (29a; 29b) with a central recess (30a; 30b) in the area of the pressure regions (24a; 24b) that runs transversely to the longitudinal axis of the contact piece carrier (7) and is positioned in such a way that it rests on the contact piece carrier (7) when preloaded and that the projection produced (32a; 32b) is located on the reverse side of the movable contact piece (7) inside the recess (30a; 30b).

12. The electrical contact system (2) according to claim 11, characterized in that the at least one spring arm (20a; 20b) has two pressure regions (24a; 24b) in opposing positions of the widened ring-shaped section (29a; 29b).

13. The electrical contact system (2) according to any of the preceding claims, characterized in that the slide (15) has a recess (35) into which the second end (12) of the contact piece carrier (7) and the free end (21) of the second spring arm section (23) of the spring element (18) project.

14. A switching device (1), comprising an electrical contact system (2) according to one of the claims 1 to 13.

15. The switching device (1) according to claim 14, further comprising an exciter coil and an armature (14), that has an operative connection to the slide (15) as a mechanical coupling element (15), characterized in that a force is generated by the exciter coil due to the magnetic field it generates which is transferred to the contact system (2) by the armature (14) and the mechanical coupling element, so that the contact system is switched by the exciter coil.

16. The switching device (1) according to any of claims 14 or 15, characterized in that the switching device (1) is a relay or comprises a relay.