Relay with first and second electromagnets for placing and keeping a contact in a closed state

Abstract

The present invention relates to a relay (1), having a first terminal (2), a second terminal (3), a contact (4) which in a closed state brings about an electrical connection between the first and second terminals (2, 3) and which in an opened state electrically disconnects the first and second terminals (2, 3), a first electromagnet (5) which is configured in such a way that it places the contact (4) in the closed state if the first electromagnet (5) is switched on, and a second electromagnet (6) which is configured in such a way that it keeps the contact (4) in the closed state if the contact (4) is in the closed state and the second electromagnet (6) is switched on.

Claims

1. A relay comprising: a first terminal; a second terminal; a contact which in a closed state brings about an electrical connection between the first and second terminals and which in an opened state electrically disconnects the first and second terminals; an armature which is mechanically connected to the contact; a first electromagnet which is configured to move the armature from a first position to a second position, thereby placing the contact in the closed state if the first electromagnet is switched on; and a second electromagnet which is an air-gap-free holding magnet and which is configured to keep the armature in the second position and to keep the contact in the closed state if the contact is in the closed state and the second electromagnet is switched on, wherein the armature abuts the second electromagnet in the second position without an air gap in-between, does not abut the second electromagnet in the first position, and does not abut the first electromagnet in the second position, and wherein the first and second electromagnet are arranged displaced from each other along the direction of the movement from the first position to the second position.

2. The relay according to claim 1, wherein the second electromagnet is dimensioned in such a way that its magnetic field is strong enough to keep the contact in the closed state, and that its magnetic field is too weak to move the contact from the opened state into the closed state.

3. The relay according to claim 1, wherein the second electromagnet is further configured to keep the contact in the closed state if the first electromagnet is switched off.

4. The relay according to claim 1, wherein the relay is configured in such a way that the first electromagnet is switched off as a result of the fact that the contact is moved from the opened state into the closed state.

5. The relay according to claim 1, having a device which switches off the first electromagnet if the contact is in the closed state.

6. The relay according to claim 1, wherein the relay has a timer switch which switches off the first electromagnet after a predefined time after the contact has been moved from the opened state into the closed state.

7. The relay according to claim 1, wherein the first electromagnet is a lifting magnet.

8. The relay according to claim 1, wherein the second electromagnet is a holding magnet.

9. The relay according to claim 1, wherein the relay is configured in such a way that the contact is moved from the closed state into the opened state if the second electromagnet is switched off.

10. The relay according to claim 1, wherein the second electromagnet is operated in a switched-on state with a power that is lower than the power with which the first electromagnet is operated in a switched-on state.

11. The relay according to claim 1, wherein the first electromagnet is configured to generate a magnetic field with a higher field strength than the second electromagnet.

12. A contactor, having a relay according to claim 1, wherein the relay is arranged in a gas-filled volume.

Description

(1) The invention will be explained in more detail below with reference to the figures and exemplary embodiments.

(2) In the drawings:

(3) FIG. 1 shows a relay in a state of rest,

(4) FIG. 2 shows the relay in an active state,

(5) FIG. 3 shows a relay according to a second exemplary embodiment in a state of rest,

(6) FIG. 4 shows the relay according to the second exemplary embodiment in an active state,

(7) FIG. 5 shows a circuit diagram of the relay, and

(8) FIG. 6 shows a circuit diagram of the relay according to an alternative embodiment.

(9) FIG. 1 shows a relay 1 which has a first terminal 2 and a second terminal 3. A contact 4 is arranged between the first and second terminals 2, 3. The contact 4 can be either in an open state or in a closed state. FIG. 1 shows the contact 4 in its opened state. In the opened state, the contact 4 electrically disconnects the first and the second terminal 2, 3 of the relay 1 from one another. Accordingly, current cannot flow via the contact 1. The relay 1 is in a state of rest which is characterized in that the contact 4 is in its opened state and accordingly current cannot flow.

(10) The relay 1 also has a first electromagnet 5 and a second electromagnet 6. The first electromagnet 5 and the second electromagnet 6 can be respectively switched on and off. In the state of rest of the relay 1 shown in FIG. 1, the first electromagnet 5 and the second electromagnet 6 are switched off.

(11) The first electromagnet 5 is a lifting magnet. The first electromagnet 5 correspondingly has an armature 7 which is moved from a first position into the second position when the first electromagnet 5 is switched on. FIG. 1 shows the armature 7 in its first position. The armature 7 is mechanically connected to the contact 4. The armature 7 has for this purpose a plate 8 on which the contact 4 is mounted. If the armature 7 is moved from its first position into its second position by the switching the first electromagnet 5 on, this also moves the contact 4. In particular, the contact 4 is as a result moved from its open state into its closed state.

(12) The second electromagnet 6 is a holding magnet. The second electromagnet 6 is dimensioned in such a way that its magnetic field is not strong enough to lift the armature 7 from the first position to the second position, but is strong enough to keep the armature 7 in the second position if it is already in the second position. In the second position, the armature 7 abuts the second electromagnet 6. Accordingly, the second electromagnet 6 is dimensioned in such a way that its magnetic field is not strong enough to move the contact 4 from the opened state into the closed state, but is strong enough to keep the contact 4 in the closed state.

(13) In addition, the relay 1 has a device 9 for switching off the first electromagnet 5. In the exemplary embodiment shown in FIG. 1, this device 9 is a micro switch. The micro switch is arranged in such a way that it is activated by the armature 7 if the armature 7 is moved from its first position into its second position. The first electromagnet 5 is switched off by activation of the micro switch.

(14) FIG. 2 shows the relay 1 in an active state. The active state of the relay 1 is characterized in that the contact 4 is in its closed state. The relay 1 is moved into the active state as a result of the first electromagnet 5 being switched on. As a result, the armature 7 is lifted from its first position into its second position and in the process closes the contact 4. The first electromagnet 5 is dimensioned, in particular, in such a way that its magnetic field is strong enough to lift the armature 7 from its first position to its second position. The first terminal 2 and the second terminal 3 of the relay 1 are then electrically connected to one another via the contact 4, with the result that current can flow through the relay 1.

(15) The first electromagnet 5 is switched on only in a transition phase between the state of rest of the relay 1 and the active state of the relay 1. In addition, in this transition phase the second electromagnet 6 is also switched on. If the relay 1 has reached its active state, the device 9 is activated to switch off the first electromagnet, and said electromagnet is correspondingly switched off. In particular, the armature 7 activates the micro switch, with the result that the latter switches off the first electromagnet 5.

(16) In the active state of the relay 1, the second electromagnet 6 is switched on. The magnetic field of the second electromagnet 6 is strong enough to keep the armature 7 in its second position, and therefore keep the contact 4 closed.

(17) The method of functioning of the relay 1 has been correspondingly divided into the two sub steps of closing of the contact 4 and keeping the contact 4 in the closed state. The first electromagnet 5 ensures that the contact 5 closes, and the second electromagnet 6 ensures that the contact 4 is kept in the closed state. A significantly stronger magnetic field is necessary to close the contact 4 than to keep the contact 4 closed.

(18) Accordingly, the first electromagnet 5 is dimensioned in such a way that it generates a magnetic field with a higher field strength than the second electromagnet 6. The first electromagnet 5 therefore also requires a higher power consumption. This higher power consumption occurs, however, only during the chronologically short process of closing the contact 4. If the contact 4 is in its closed state, only the second electromagnet 6 is switched on, while the first electromagnet 5 is switched off. Therefore, in the closed state of the contact 4 only the relatively low power consumption of the second electromagnet 6 occurs. For example, in the active state the relay 1 can have a power consumption of 250 mA or less, for example a power consumption in a range between 40 and 250 mA, in particular between 50 and 150 mA.

(19) In order then to reset the relay 1 from its active state to its state of rest, the second electromagnet 6 is switched off. In this case, the contact 4 is no longer kept in the closed state and is correspondingly opened. In particular, in this case the armature 7 is moved from its second position back into its first position.

(20) Since only a low current flows when the second electromagnet 6 is switched off, the overall fall-back time when the contact 4 opens is very short, since only a comparatively small magnetic field has to be removed.

(21) FIGS. 3 and 4 show the relay 1 according to a second exemplary embodiment. In this context, FIG. 3 shows the relay 1 according to the second exemplary embodiment in its state of rest, and FIG. 4 shows the relay 1 in its active state.

(22) The relay 1 according to the second exemplary embodiment differs from the relay 1 shown in FIGS. 1 and 2 in that the armature 7 of the first electromagnet 5 is mechanically connected to a resetting spring 13. If the armature 7 is in its second position, the resetting spring 13 is tensioned and applies a force in the direction of the first position to the armature 7. The resetting spring 13 is, however, dimensioned in such a way that the force applied by it to the armature 7 is not sufficient to overcome the force applied by the second electromagnet 6. Accordingly, the armature 7 remains in its second position as long as the second electromagnet 6 is switched on.

(23) If the second electromagnet 6 is switched off, only the resetting spring 13 continues to act. Said resetting spring 13 then pulls the armature 7 back into its first position, with the result that the contact 4 is opened and the relay 1 is moved into its state of rest. The restoring spring 13 therefore permits the contact 4 to be opened even more quickly, and the relay 1 to be moved more quickly from its active state into its state of rest. The switch-off time of the relay 1 is influenced by the following factors: an electromagnet 5, 6 always attempts to maintain the current state. If the electromagnet 5, 6 is switched off from the energized state, it takes some time until the state of rest is set. In this time, a magnetic force also continues to act on the armature 7. This causes the switch-off process of the relay 1 or the opening of the contact 4 to take a certain time. However, the fastest possible switching off is desired in order to avoid a flashover. Since the first electromagnet 5 is switched off immediately after the switching the relay 1 on, its switch-off period is negligible. In particular, if the first electromagnet is a lifting magnet, it can have a comparatively slow switch-off behavior. However, this is not of further significance since the first electromagnet 5 is switched off while the relay 1 is in its active state. The second electromagnet 6 can be, in particular, a holding magnet which no longer applies any force to the attracted armature 7 immediately after the switching off, with the result that no further influence from the second electromagnet 6 is possible. The contact 4 is therefore also opened very quickly in the exemplary embodiment shown in FIGS. 1 and 2. The opening time of the contact 4 can be shortened even further by the resetting spring 13.

(24) In addition, the relay 1 according to the second exemplary embodiment also differs from the relay 1 shown in FIGS. 1 and 2 in that here the device 9 for switching off the first electromagnet 5 does not have a switch which is activated by the armature 7. Instead, the device 9 has a timer switch which switches off the first electromagnet 5 again after a predefined time after the first electromagnet 5 switches on. This timer switch cannot be seen in FIGS. 3 and 4, but is explained in more detail later.

(25) FIG. 5 shows a circuit diagram of the relay 1. The circuit diagram shows that the first electromagnet 5 and the second electromagnet 6 are connected to one another in parallel. The circuit diagram also has a device 10 for switching the relay 1 on and off. Said device 10 is a switch. If the device 10 is closed in order to switch on, the relay 1 is moved from its state of rest into its active state. In this context, a voltage is firstly applied to the first electromagnet 5 and to the second electromagnet 6, with the result that both electromagnets 5, 6 are switched on.

(26) In addition, the device 9 which switches off the first electromagnet again a short time after it switches on is connected in series with the first electromagnet 5. This device 9 is the micro switch here which is activated by a movement of the armature 7.

(27) The relay 1 which is shown in FIG. 5 is configured in such a way that the first electromagnet 5 is switched off immediately as soon as the contact 4 is in the closed state.

(28) In addition, two diodes 11, 12 which are connected counter to one another are connected in parallel with the first electromagnet 5, wherein the diode 11 is a simple diode, and the diode 12 is a Zehner diode. The two diodes 11, 12 ensure that when the first electromagnet 5 switches off, the voltage is short-circuited and therefore disruptive effects during the removal of the magnetic field are damped. As an alternative to the two diodes 11, 12, a varistor could also be connected in parallel with the first electromagnet 5.

(29) FIG. 6 shows a circuit diagram of an alternative embodiment of the relay 1. This relay 1 is configured in such a way that the first electromagnet 5 is switched off after a predefined, preferably very short, time, after the contact 4 has reached the closed state. For this purpose, in the case of the relay 1 the device 9 has a capacitor 14 and a resistor 15 instead of the micro switch. The capacitor 14 is connected in series with the first electromagnet 5. After the relay 1 switches on, firstly a current can flow across the capacitor 14, with which current the first electromagnet 5 is operated. If the capacitor 14 is then completely charged, it switches off, with the result that current no longer flows and the first electromagnet 5 is switched off. Accordingly, the capacitor 14 forms a timer switch which ensures that the first electromagnet 5 is switched off after a predefined time after the closing of the contact 4.

LIST OF REFERENCE NUMBERS

(30) 1 Relay 2 First terminal 3 Second terminal 4 Contact 5 First electromagnet 6 Second electromagnet 7 Armature 8 Plate 9 Device for switching off the first electromagnet 10 Device for switching the relay on and off 11 Diode 12 Diode 13 Resetting spring 14 Capacitor 15 Resistor