Safety switching device for fail-safely disconnecting an electrical load
A safety switching device for fail-safely disconnecting an electrical load has an input part for receiving a safety-relevant input signal, a logic part for processing the at least one safety-relevant input signal, and an output part. The output part has a relay coil and four relay contacts. The first and second relay contacts are arranged electrically in series with one another. The third and fourth relay contacts are also arranged electrically in series with one another. The first and the third relay contacts are mechanically coupled to each other and form a first group of positively driven relay contacts. The second and the fourth relay contacts are mechanically coupled to each other and form a second group of positively driven relay contacts. The logic part redundantly controls the first and the second groups of positively driven relay contacts to selectively allow, or to interrupt in a fail-safe manner, a current flow to the electrical load, depending on the safety-relevant input signal. The relay coil is electromagnetically coupled to the first and second groups of positively driven relay contacts so that the logic part can control the relay contacts together via a single relay coil.
1. A safety switching device for fail-safely disconnecting an electrical load, comprising:
an input part for receiving at least one safety-relevant input signal,
a logic part connected to the input part for processing the at least one safety-relevant input signal, and
an output part which comprises a relay coil and a first relay contact, a second relay contact, a third relay contact, and a fourth relay contact,
wherein the first and the second relay contacts are arranged electrically in series with one another,
wherein the third and the fourth relay contacts are arranged electrically in series with one another,
wherein the first and the third relay contacts are mechanically coupled to each other so as to form a first group of positively driven relay contacts,
wherein the second and the fourth relay contacts are mechanically coupled to each other so as to form a second group of positively driven relay contacts,
wherein the first and the third relay contacts can move mechanically separately from the second and the fourth relay contacts,
wherein the logic part is connected to the output part and redundantly controls the first group of positively driven relay contacts and the second group of positively driven relay contacts in order to selectively allow, or to interrupt in a fail-safe manner, a current flow to the electrical load, in response to the at least one safety-relevant input signal, and
wherein the relay coil comprises a single relay coil that is electromagnetically coupled to the first group and to the second group of positively driven relay contacts so that the logic part can control the first relay contact, the second relay contact, the third relay contact, and the fourth relay contact together via the single relay coil.
2. The safety switching device of claim 1 , further comprising a first switching element and a second switching element which are arranged electrically in series with the single relay coil and are coupled to the logic part so that the logic part can interrupt a control current through the single relay coil using at least one of the first and the second switching element.
3. The safety switching device of claim 2 , wherein the logic part comprises a first evaluation channel and a second evaluation channel, wherein the first and the second evaluation channels each redundantly control the first and the second switching elements.
4. The safety switching device of claim 2 , wherein the first switching element is arranged upstream and the second switching element is arranged downstream from the single relay coil.
5. The safety switching device of claim 2 , further comprising a shunt resistor which is situated downstream from the first and the second switching elements.
6. The safety switching device of claim 1 , wherein the logic part is configured to determine an instantaneous control current through the single relay coil.
7. The safety switching device of claim 1 , wherein the logic part is configured to maintain a control current through the single relay coil at a defined current value.
8. The safety switching device of claim 1 , wherein the logic part is configured to determine an instantaneous voltage at the relay coil and to interrupt, depending thereon, a control current through the single relay coil.
9. The safety switching device of claim 1 , further comprising a component housing wherein the single relay coil and the first, the second, the third, and the fourth relay contacts all are accommodated, said component housing being mounted on a circuit board.
10. The safety switching device of claim 1 , wherein the first and second relay contacts each are designed as normally open contacts, and wherein the third and the fourth relay contacts each are designed as normally closed contacts.
11. The safety switching device of claim 1 , wherein the single relay coil drives at least one movable armature coupled to the relay contacts, and wherein the output part comprises an optical detector with the aid of which the logic part can detect at least one armature position of the at least one movable armature.
12. The safety switching device of claim 11 , wherein the optical detector comprises a light transmitter, a light receiver and an optical waveguide which extends from at least one of the light transmitter and the light receiver to the at least one movable armature.
13. The safety switching device of claim 1 , wherein the single relay coil drives at least one movable armature which is coupled to the relay contacts, and the logic part is configured to adjust a control current through the relay coil depending on an armature position of the at least one movable armature.
14. The safety switching device of claim 1 , wherein the single relay coil is spatially arranged between the first group of positively driven relay contacts and the second group of positively driven relay contacts.
15. A safety switching device relay component, comprising:
a relay coil,
a first relay contact, a second relay contact, a third relay contact, and a fourth relay contact, and
a component housing, in which the relay coil and the first relay contact, the second relay contact, the third relay contact and the fourth relay contact are accommodated,
wherein the first and the second relay contacts are arranged electrically in series with one another,
wherein the third and the fourth relay contacts are arranged electrically in series with one another,
wherein the first and the third relay contacts are mechanically coupled to each other so as to form a first group of positively driven relay contacts,
wherein the second and the fourth relay contacts are mechanically coupled to each other so as to form a second group of positively driven relay contacts,
wherein the first and the third relay contacts can move mechanically separately from the second and the fourth relay contacts, and
wherein the relay coil is electromagnetically coupled to the first group of positively driven relay contacts and to the second group of positively driven relay contacts so that a control current in the relay coil can control the first relay contact, the second relay contact, the third relay contact, and the fourth relay contact together.