WO2001020632A1

WO2001020632A1 - Electromagnetic switchgear

Info

Publication number: WO2001020632A1
Application number: PCT/DE2000/003076
Authority: WO
Inventors: Kurt Held
Original assignee: Siemens Aktiengesellschaft
Priority date: 1999-09-16
Filing date: 2000-09-06
Publication date: 2001-03-22
Also published as: CN1214427C; DE50003215D1; EP1212772B1; EP1212772A1; DE19944462C1; CN1372693A

Abstract

The invention relates to an electromagnetic switchgear comprising an opening driver element (7) with which a contact driver (3) can be displaced out of an inoperative position (R) and into an operative position (B). To this end, a contact bridge (8) of a break contact (5) is lifted by mating contacts (9) of the break contact (5). The contact bridge (8) is held in the opened position by a holding device (12) until it is driven by a closing driver element (18). The break contact (5) is thus actuated by a switching hysteresis.

Description

description

Electromagnetic switching device

The present invention relates to an electromagnetic switching device with at least one drive coil which, when acted upon by a pull-in current, shifts a contact driver from a rest position into an actuating position, the contact driver having an opening driving element by means of which when the contact driver is moved into the actuating position when an intermediate position is reached a contact bridge of an opener is lifted from counter contacts of the opener in the rest position and the actuation position of the opening-entraining division.

Such an electromagnetic switching device is generally known.

In the prior art, the contact bridge is also constantly pressed against the opening-driving element in the actuated position via a reset element. When the contact driver is returned to the rest position, the contact bridge is therefore lowered again to the counter contacts when the opening-driving division is reached. In some applications, however, such a lowering when the opening driving position is reached is undesirable. Rather, the switching behavior of the break contact should have a hysteresis.

An example of an application in which the switching behavior of the NC contact should have a hysteresis is an economy circuit for the drive coil: If the NC switch is used to switch from pull-in to holding current, the required holding current is particularly small when the NC contact is only brief is opened before reaching the actuation position. In the event of a voltage drop that occurs in practice

(short-term voltage failure or voltage drop), this can lead to a drop in the holding current the actuation position is exited and the main contacts to be switched open.

If there is now a hysteresis-free changeover of the break contact, the break contact is closed again when the opening driving position is reached and the drive coil is thus immediately subjected to the starting current again. This causes the contact driver to be tightened again and the opener to be opened again. As a result of this constant switching of the current with which the drive coil is acted on, it can happen that the main contacts flutter or abut one another without pressure. This leads to great wear on the main contacts, possibly even welding of the main contacts.

If, on the other hand, there is a hysteresis-related changeover of the break contact, a voltage drop only leads to either the main contacts dropping out or the contactor being switched on again after voltage recovery. A flutter or pressure-free contact of the main contacts is avoided.

The object of the present invention is to provide an electromagnetic switching device in which the opener can be operated with a hysteresis.

The object is achieved in that the contact driver has a closing driving element, by means of which, when the contact driver is moved into the rest position when a closing driving position lying between the rest position and the opening driving position is reached, the contact bridge is moved towards the counter contacts and that the opener has one Holding device is assigned, which holds the contact bridge in an open position, in which the contact bridge is lifted from the mating contacts, as long as the contact driver is moved from the open driving position to the closing driving position. The holding device is particularly simple if the holding device is designed as a magnetic device and the contact bridge is at least partially made of a ferromagnetic material.

If the magnetic device is designed as a permanent magnetic device, the magnetic device is particularly effective.

If the magnet device has two magnets and one of the magnets acts on one of two end regions of the contact bridge, the magnet device is particularly simple in construction. In addition, the stray field caused by the magnetic device acts as a blowing field for any arcing that may occur when the contact bridge is lifted from the mating contacts.

If the contact bridge has a rear side facing away from the counter contacts, which is made of a ferromagnetic material, the magnet device exerts a pulling and holding force on the contact bridge. This is particularly important in the case of applications at risk of vibration.

If the opening driving element is arranged in such a way that it lifts the contact bridge up to an intermediate lifting position from the mating contacts, and the holding device is designed such that it transfers the contact bridge from the intermediate lifting position into the opening position, the risk of damage to the contact bridge is reduced in a simple manner Avoid transfer to the open position.

If the closing driving element is arranged in such a way that it deflects the contact bridge into an intermediate lowering position from the open position, and a reset element is assigned to the contact bridge, which lowers the contact bridge from the intermediate lowering position to the mating contacts, the risk of damage to the contact bridge is reduced in a simple manner Lowering on the counter contacts avoided. In the simplest case, the restoring element is designed as a restoring spring. The return spring can be supported, for example, on the one hand on the contact bridge and on the other hand on a bearing which is stationary with respect to the switching device.

If the break contact is connected to a current setting device for the drive coil in such a way that when the break contact is opened or closed there is a change in the current applied to the drive coil, the electromagnetic switching device can be switched over in a particularly simple manner. on holding current. In particular, it is possible with this arrangement to switch the switching device from pull-in to holding current only shortly before reaching the actuation position and to switch on the pull-in current only shortly before reaching the rest position. Despite the lifting of the contact bridge from the mating contacts, a large distance of the contact bridge from the mating contacts can only be reached shortly before the actuation position is reached, so that there is no risk of a non-extinguishing arc.

Further advantages and details emerge from the following description of an exemplary embodiment. Show in principle

1 shows an electromagnetic switching device with a current setting device, FIG. 2 shows a switching device with a contact driver in the rest position, FIG. 3 shows a switching device with a contact driver in the actuating position,

4 shows the switching device from FIG. 1 from above and FIG. 5 shows a hysteresis diagram.

According to FIG. 1, an electromagnetic switching device has a drive coil 1. If an actuation command is given to a current setting device 2 for the drive coil 1, the current setting device 2 acts on the Drive coil 1 with a current I. The current I has at least the size of a starting current I _A. As a result, a contact driver 3 —shown only schematically in FIG. 1 —is displaced from a rest position R into an actuation position B.

At the beginning of the displacement process, a main contact 4 of the switching device is not actuated and an NC contact 5 is closed. By moving the contact carrier 3, the main contact 4 is actuated and the break contact 5 is opened.

The opener 5 bridges a resistor 6. When the opener 5 is opened, the drive coil 1 is thus only connected to the current setting device 2 via the resistor 6, but no longer without resistance via the opener 5. Therefore, when the opener 5 opens, the current I drops to a holding current I _H. Conversely, when the opener 5 closes, the current I increases again to the starting current I _A. The opener 5 is thus connected to the current setting device 2 in such a way that a change in the current when the opener 5 is opened or closed

I, with which the drive coil 1 is acted on.

According to FIGS 2 to 4, the contact driver 3 has an opening driving element 7. According to the exemplary embodiment, the opening driving element 7 is designed as a driving surface.

By means of the opening driving element 7, a contact bridge 8 of the opener 5 is lifted from mating contacts 9 of the opener 5 when the contact driver 3 is moved into the actuation position B. The contact bridge 8 is then only lifted from the mating contacts 9 when the contact driver

3 reaches an opening driving position Ml.

The contact bridge 8 is lifted off against the force of a restoring element 10, which is designed as a restoring spring according to FIGS. 2 to 4. The return spring 10 is supported on the one hand on the contact bridge 8 and on the other hand on a bearing 11 which is stationary with respect to the switching device is. The return spring 10 is guided to the side by suitable, generally known guide elements. For the sake of clarity, these are therefore not shown.

As can be seen from FIG. 3, the opening driver element 7 is arranged in such a way that it lifts the contact bridge 8 into an intermediate lifting position ZI. When the contact bridge 8 has reached the intermediate lifting position ZI, it is exposed to a magnetic force which is exerted on it by a magnetic device 12. The magnet device 12 serves as a holding device 12 and is assigned to the opener 5.

The magnet device has two permanent magnets 13, 14. It is therefore designed as a permanent magnet device. One of the permanent magnets 13, 14 acts on one of two end regions 15, 16 of the contact bridge 8. The contact bridge 8 consists at least partially of a ferromagnetic material. In particular, the contact bridge 8 has a rear side 17 which faces away from the mating contacts 9 and is made of a ferromagnetic material.

The restoring element 10 and the magnetic device 12 are matched to one another and the intermediate lifting position ZI is selected such that in the intermediate lifting position ZI the magnetic force exerted by the magnetic device 12 on the contact bridge 8 is greater than the restoring force which the restoring element 10 exerts on the contact bridge 8 , The magnet device 12 therefore transfers the contact bridge from the intermediate lifting position ZI to an open position in which the contact bridge 8 bears against the permanent magnets 13, 14 and is lifted off the counter contacts 9.

When the holding current I _H drops below a minimum value (switching device switched off, supply voltage drops), the restoring force outweighs the holding torque applied by drive coil 1. As a result, the contact driver 3 is moved from the actuation position B to the rest position R LO tt h- ¹ H ooo cn rr co α <t N H- σ 3 HO ω Di <tr P s: H φ Ά <Φ N n H- O φ 0 Φ Φ H- CO s; oo t φ 3 Φ rt Φ O c H- P ⁾ H- H- P- M Φ o Φ c tr iQ s; ω co P- φ rt 0- ff 3 Φ ri PPO ff φ H n P ^ P Φ

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Claims

claims

1. Electromagnetic switching device with at least one drive coil (1) which, when acted upon by a pull-in current (I _A ), shifts a contact driver (3) from a rest position (R) to an actuation position (B), the contact driver (3 ) an opening driving element

(7), by means of which, when the contact carrier (3) is moved into the actuation position (B) when an opening entrainment position lying between the rest position (R) and the actuation position (B) is reached

(Ml) a contact bridge (8) of an opener (5) is lifted from mating contacts (9) of the opener (5), so that the contact driver (3) is a closing drive element

(18), by means of which, when the contact driver (3) is moved into the rest position (R) when a closing driver position (M2) lying between the rest position (R) and the opening driving position (Ml) is reached, the contact bridge (8) on the mating contacts (9 ) is moved and that the opener (5) is assigned a holding device (12) which holds the contact bridge (8) in an open position in which the contact bridge (8) is lifted from the counter contacts (9) as long as the contact it - User (3) is shifted from the opening driving position (Ml) to the closing driving position (M2).

2. Switching device according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the holding device (12) is designed as a magnetic device (12) and that the contact bridge (8) consists at least partially of a ferromagnetic material.

3. Switching device according to claim 2, characterized in that the magnetic device (12) is designed as a permanent magnet device (12).

4. Switching device according to claim 2 or 3, characterized in that the magnet device (12) has two magnets (13, 14) and that one of the magnets (13, 14) on one of two end regions (15, 16) of the contact bridge ( 8) works.

5. Switching device according to claim 2, 3 or 4, d a d u r c h g e k e n n z e i c h n e t that the contact bridge (8) has a rear side (17) facing away from the mating contacts (9), which consists of a ferromagnetic material.

6. Switching device according to one of the above claims, characterized in that the opening driving element (7) is arranged such that it lifts the contact bridge (8) up to an intermediate lifting position (ZI) from the mating contacts (9), and that the holding device (12) is designed such that it transfers the contact bridge (8) from the intermediate lifting position (ZI) to the open position.

7. Switching device according to one of the above claims, characterized in that the closing driving element (18) is arranged such that it deflects the contact bridge (8) into an intermediate lowering position (Z2) from the open position and that the contact bridge (8) has a reset element (10 ) is assigned, which lowers the contact bridge (8) from the intermediate lowering position (7,2) to the counter contacts (9).

8. Switching device according to claim 7, characterized in that the return element (10) is designed as a return spring (10).

9. Switching device according to claim 8, so that the return spring (10) is supported on the one hand on the contact bridge (8) and on the other hand on a stationary bearing (11) with respect to the switching device.

10. Switching device according to one of the above claims, characterized in that the break contact (5) is connected to a current setting device (2) for the drive coil (1) in such a way that when the break contact (5) opens or closes, a change in the current (I ) with which the drive coil (1) is acted on.