EP2755222B1 - Switch lock for low voltage protection devices - Google Patents

Description

The invention relates to a switch lock, in particular for low-voltage protection devices with a knee joint, which comprises a handle and a first U-bracket attached thereto, wherein in the handle a spring element is arranged and wherein the first U-bracket is mechanically in operative connection with a pawl, which mechanically operatively connected to a shift lever via a second U-bracket, as well as a protective device.

When the protective device is switched on, at least one switch-off spring is preloaded in the switch lock. The protective device is designed so that current monitoring groups such as bimetal triggers, continuously measure the flow of current in a branch line. If the current flow exceeds a defined threshold value, the opening spring, which is pre-tensioned in the switch lock, is unlatched. The unlatched spring force is transmitted to the main contacts via the switch lock mechanism, which are then opened. As a result, the flow of current is interrupted.

In practical use, a low-voltage protection device has a rather passive task, that is, it is switched on once after installation in a control cabinet and remains in this state until a system failure occurs. But since a system failure occurs very rarely, it is common that the switching mechanism in the low-voltage protection device is not operated for decades. There is therefore the risk that components in the switch lock will fail unnoticed due to aging and the protective device will no longer function. In particular, the biased opening springs constitute a potential hazard. For example, hydrogen embrittled feathers in new condition show no abnormalities, but tend, with appropriate bias to break after months.

There is another trend in the market, which is to use circuit breakers in safety-related controls as a redundant switching element to a contactor in order to achieve a higher safety integrity level. In such a circuit is on a contactor on and off. The contactor is monitored by a safety evaluation device. If a switch-off fails, the circuit-breaker is triggered or switched off via an undervoltage release. Since a circuit breaker usually has to be switched on manually, an automatic monitoring of the circuit breaker is very expensive. For this reason, such circuits are only interesting in applications that require a low switching frequency operationally.

In order to minimize the risk that components in the switch lock will fail unnoticed due to aging and as a result the protective device will no longer function, the components in the switch lock are usually oversized. In addition, during the development extensive life and long-term tests are made. Nevertheless, there remains a residual risk, as defective material batches in series production can not be ruled out 100%, such as springs embrittled with hydrogen.

The WO 2004/073008 A1 describes a switch lock with a knee joint, which comprises a handle with a first attached thereto U-bracket 1, wherein in the handle a spring element is arranged and wherein the first U-Büge1 mechanically in operative connection with a pawl, which via a second U-büge1 mechanically in operative connection with a shift lever.

Also the DE 197 03 959 C1 describes a switching mechanism of a switching device with rotary drive. The switch lock has a counter-wheel, which forms a knee joint in conjunction with a U-bracket1. The knee joint is in a backdrop in one Circuit board led. Other attached to the circuit board components of the switch latch are a latch lever, a pawl, a lever, a switch-off spring and a lock.

A similar switch lock goes also from the DE 297 01 829 U1 out.

Alternative solutions to the problem presented here result from the DE 468 987 C , of the US 3 432 787 A , of the DE 722 734 C as well as the DE 652 199 C ,

Accordingly, the object of the present invention is to provide a switch lock, in particular for low-voltage protection devices and a corresponding protection device, which works reliably and minimizes the risk of unrecognized material defects.

This object is achieved by a switching mechanism, in particular for low-voltage protective devices with the features of claim 1 and by a protective device with the features of claim 10. Further embodiments of the invention will become apparent from the dependent claims, the description and the drawings.

According to the invention, this object is achieved by a switch lock, in particular for low-voltage protective devices with a knee joint, which comprises a handle and a first U-bracket attached thereto, wherein in the handle a spring element is arranged and wherein the first U-bracket mechanically in operative connection with a pawl is, which is mechanically connected via a second U-bracket with a shift lever. The invention is characterized in that the spring element in the handle is designed such that the knee joint remains stretched under load with a plurality of opening springs, but moves under load with only one opening spring in the off position.

The invention also includes a protective device with a switch lock according to the invention.

The switching mechanism according to the invention has a knee joint, which comprises a handle, which is preferably designed as a toothed rocker, and a first U-bracket, wherein in the handle a spring element, preferably a torsion spring, is arranged. The U-bracket has two legs, which are arranged on the one hand in the handle and the other in a pawl. On the pawl, a second U-bracket is arranged, which connects the pawl mechanically with the shift lever. This switching mechanism is arranged between two circuit boards.

In addition, the switching mechanism according to the invention a plurality, in particular at least two Ausschaltfedern on. In this case, the first opening spring is preferably designed as a torsion spring, with two ends, wherein the one end is attached to the shift lever and the other end to a first extension of a circuit board. The second opening spring is preferably designed as a tension spring and also has two ends, wherein the one end is attached to a second extension of a circuit board and the other end to the shift lever.

In the on position, the handle, in particular toothed rocker, in which a torsion spring is arranged, applied with a torque "Mdf" counterclockwise. Counteracts this torque with the lever arm "H" the force "F". The torque "F" x "H" is greater in the switched-on position than the torque "Mdf".

So that the toothed rocker does not move in a clockwise direction, a stop is provided in the housing. The force "F" comes from a prestressed opening spring, which is tensioned during the switch-on process, and whose force is transmitted via several mechanical parts to the upper U-bar. In addition, the torque "Ma" acts clockwise in the switched position on the shift lever.

F_zugfeder entspricht der Kraftwirkung am oberen, ersten U-Bügel, die von einer irgendwo im Getriebe angeordneten Zugfeder herrührt.The feature essential to the invention is that at least two opening springs are provided in the switching mechanism with knee joint. These may be, for example, a tension spring and a torsion spring. This gives the equation for the force F acting on the upper U-bar: $$\mathrm{F}={\mathrm{F}}_{\mathrm{mainspring}}+{\mathrm{F}}_{\mathrm{torsion\; spring}}\mathrm{respectively}\mathrm{,}\mathrm{F}={\mathrm{F}}_{\mathrm{1}}+{\mathrm{F}}_{\mathrm{2}}$$

F _{tension spring} corresponds to the force acting on the upper, first U-bracket, which originates from a tension spring located somewhere in the transmission.

F _torsion corresponds to the force acting on the upper, former U-bracket, which originates from a torsion spring located somewhere in the transmission.

Each individual opening spring is dimensioned in terms of power so that it can open the main contacts alone a small piece. The opening travel, which can be achieved by a switch-off spring, is so great that at rated voltage, a current flow through the main contacts comes to a standstill. The effect of the return spring in the toothed rocker ("Mdf") is so dimensioned so that the knee joint remains stretched when loaded with two Ausschaltfedern, but is moved when loaded with only one opening spring in the off position counterclockwise.

The invention is characterized in that the effect of the return spring in the handle, so in the toothed rocker is dimensioned so that the knee joint under load with two opening springs remains stretched, but is moved under load with only one opening spring in the off position. The advantage is that when a break-off spring breaks in the switch lock, the low-voltage protection device switches off automatically. The plant comes to a standstill and the fault is detected even before a dangerous situation occurs.

According to the invention it can be provided that the low-voltage protection device is preferably a circuit breaker or a motor branch.

In a particularly advantageous embodiment it can be provided that the handle is designed as a toothed rocker.

Furthermore, it can be provided in a particularly advantageous embodiment that the spring element is designed as a torsion spring.

It is also conceivable that the first opening spring is designed as a torsion spring.

According to the invention it is provided that the first opening spring has two ends, wherein the one end is fastened to the shift lever and the other end to a first extension of a circuit board.

According to the invention can also be provided that a second opening spring is designed as a tension spring. It is inventively provided that the second opening spring has two ends, wherein one end is attached to a second extension of a circuit board and the other end on the shift lever.

The invention also includes a protective device, in particular a low-voltage protection device, with a switching mechanism according to the invention.

The switching mechanism according to the invention is characterized in that the action of the return spring in the handle is dimensioned so that the knee joint is stretched under load with two opening springs, but is moved under load with only one opening spring in the off position. This concept according to the invention has the advantage that when a break-off spring breaks in the switching mechanism, the low-voltage protection device switches off automatically. The plant comes to a halt and the fault is detected even before a dangerous situation occurs. The switching mechanism according to the invention thus enables reliable operation and minimizes the risk of unrecognized material defects.

Further advantages and embodiments of the invention will be explained below with reference to an embodiment and with reference to the drawing.

• Fig. 1 in einer Seitenansicht ein erfindungsgemäßes Schaltschloss mit Kräftediagramm in eingeschalteter Schaltstellung;
• Fig. 2 in einer perspektivischen Darstellung das erfindungsgemäße Schaltschloss nach Fig. 1 mit zwei Ausschaltfedern.

Here are shown schematically:

• Fig. 1 in a side view of an inventive switching mechanism with force diagram in switched-switch position;
• Fig. 2 in a perspective view of the switching mechanism according to the invention Fig. 1 with two opening springs.

Fig. 1 shows the switching mechanism 1 according to the invention, which has a knee joint, which comprises a handle 2, which is preferably designed as a toothed rocker, and a first U-bracket 3, wherein in the handle 2, a spring element 4, preferably a torsion spring is arranged. The U-bracket 3 has two legs 5, 6, which are arranged on the one hand in the handle 2 and on the other hand in a pawl 7. On the pawl 7, a second U-bracket 8 is arranged, which connects the pawl 7 mechanically with a shift lever 9. In the switched-on switching position, the spring element 4 acts on the handle 2 with the torque "Mdf" in the counterclockwise direction. This torque counteracts the force "F" with the lever arm "H". The torque "F" x "H" is greater than the torque "Mdf" in the illustrated switched position. So that the handle does not move in a clockwise direction, a stop is provided in the housing. The force "F" comes from a prestressed opening spring, which is tensioned during the switch-on process and whose force effect is transmitted to the U-bracket 3 via a plurality of mechanical parts.

In Fig. 2 is the switching mechanism 1 according to the invention in the installed state between two circuit boards 10, 11 shown. Out Fig. 2 shows that the switching mechanism according to the invention a plurality, in particular at least two Ausschaltfedern 12, 13 has. In this case, the first opening spring 12 is preferably designed as a torsion spring with two ends, wherein one end is attached to the shift lever 9 and the other end to a first extension 14 of the circuit board 11. The second opening spring 13 is preferably designed as a tension spring and also has two ends, wherein one end is attached to a second extension 15 of the circuit board 11 and the other end to the shift lever 9.

F_zugfeder entspricht der Kraftwirkung am oberen, ersten U-Bügel, die von einer irgendwo im Getriebe angeordneten Zugfeder herrührt.The feature essential to the invention is that at least two opening springs are provided in the switching mechanism with knee joint. This can be for example a To be tension spring and a torsion spring. This gives the equation for the force F acting on the upper U-bar: $$\mathrm{F}={\mathrm{F}}_{\mathrm{mainspring}}+{\mathrm{F}}_{\mathrm{torsion\; spring}}\mathrm{respectively}\mathrm{,}\mathrm{F}={\mathrm{F}}_{\mathrm{1}}+{\mathrm{F}}_{\mathrm{2}}$$

F _{tension spring} corresponds to the force acting on the upper, first U-bracket, which originates from a tension spring located somewhere in the transmission.

F _torsion corresponds to the force acting on the upper, former U-bracket, which originates from a torsion spring located somewhere in the transmission.

$$"{\mathrm{F}}_{\mathrm{1}}"\times "\mathrm{H}"<"\mathrm{Mdf}"$$

und $$"{\mathrm{F}}_{\mathrm{2}}"\times "\mathrm{H}"<"\mathrm{Mdf}"$$

Each individual opening spring is dimensioned in terms of power so that it can open the main contacts alone a small piece. The opening travel, which can be achieved by a switch-off spring, is so great that at rated voltage, a current flow through the main contacts comes to a standstill. The action of the return spring in the toothed rocker ("MDF") is dimensioned so that the knee joint remains stretched under load with two opening springs, but is moved in the off position counterclockwise when loaded with only one opening spring. $$"{\mathrm{F}}_{\mathrm{1}}+{\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="imgf0002.png"\; state="\{\{state\}\}">F</figure-callout>}}_{\mathrm{2}}"\times "\mathrm{H}">"\mathrm{mDF}"$$

$$"{\mathrm{F}}_{\mathrm{1}}"\times "\mathrm{H}"<"\mathrm{mDF}"$$

and $$"{\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="imgf0002.png"\; state="\{\{state\}\}">F</figure-callout>}}_{\mathrm{2}}"\times "\mathrm{H}"<"\mathrm{mDF}"$$

The invention is characterized in that the effect of the return spring in the handle, so in the toothed rocker is dimensioned so that the knee joint under load with two opening springs remains stretched, but is moved under load with only one opening spring in the off position. The advantage is that when a break-off spring breaks in the switch lock, the low-voltage protection device switches off automatically. The plant comes to a standstill and the fault is detected even before a dangerous situation occurs.

The switch lock according to the invention enables reliable operation and minimizes the risk of unrecognized material defects.

Claims (10)

1. Latching mechanism (1), in particular for low-voltage protection devices, having a toggle joint which comprises a handle (2) with a first U-shaped bracket (3) attached to it, wherein a spring element (4) is arranged in the handle (2), and wherein the first U-shaped bracket (3) is mechanically operatively connected to a latch (7) which is mechanically operatively connected to a switching lever (9) by means of a second U-shaped bracket (8), characterized in that the spring element (4) is formed in the handle (2) in such a way that the toggle joint remains extended when loaded with a plurality of disconnection springs (12, 13) but moves to the switched-off position when loaded with only one disconnection spring (12 or 13), wherein each individual disconnection spring (12, 13) is dimensioned in respect of force such that it can open the main contacts to a slight extent on its own, and wherein, in the connected switching position, the spring element (4) acts on the handle (2) with a first torque ("Mdf"), and wherein a second torque counteracts the first torque by way of a lever arm ("H") and a force ("F"), and wherein the second torque ("F" x "H") is greater than the first torque ("Mdf") in the connected switching position.
2. Latching mechanism (1) according to Claim 1, characterized in that the handle (2) is in the form of a toothed rocker.
3. Latching mechanism (1) according to Claim 1 or 2, characterized in that the spring element (4) is in the form of a rotary spring.
4. Latching mechanism (1) according to one of the preceding claims, characterized in that a first disconnection spring (12) is in the form of a rotary spring.
5. Latching mechanism (1) according to Claim 4, characterized in that the first disconnection spring (12) has two ends, wherein one end is fastened to the switching lever (9) and the other end is fastened to a first projection (14) from a circuit board (11).
6. Latching mechanism (1) according to one of the preceding claims, characterized in that a second disconnection spring (13) is in the form of a tension spring.
7. Latching mechanism (1) according to Claim 6, characterized in that the second disconnection spring (13) has two ends, wherein one end is fastened to a second projection (15) from a circuit board (11) and the other end is fastened to the switching lever (9).
8. Protection device, in particular low-voltage protection device, comprising a latching mechanism according to one of Claims 1 to 7.
9. Protection device according to Claim 8, characterized in that the low-voltage protection device is a circuit breaker.
10. Protection device according to Claim 8, characterized in that the low-voltage protection device is a motor feeder.

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