JP2001145253A - Electromechanical switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromechanical switching device that has at least one mechanical switching contact especially for a safety circuit such as a safety relay unit. SOLUTION: An electromechanical switching device 10 is provided with a sensor 26 for monitoring the connection state of a mechanical switching contact 12 to obtain high safety even if no mechanical forced guide by at least one mechanical switching element is available.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electromechanical switching device for a safety circuit, for example a safety relay unit, which has at least one electrical switching contact and whose connection is monitored by an optical sensor.

[0002]

BACKGROUND OF THE INVENTION A signaling device for a contactor or switch is disclosed in DE-A-2306.
No. 207 is known. In order to monitor the connection state of the switchgear, two elements that move relative to each other are arranged in the switchgear, one of which is fixed,
The other element is connected to a member that changes its spatial position by a switching movement, so that the relative movement of the two elements changes the quantity of electricity without contact and without direct contact. An electro-optical coupler is provided as a fixed element, which can be adjusted by a movable element formed as a diaphragm.

An optical monitoring system with a sensor for monitoring the connection status of the contacts of a disconnector is disclosed in French Patent No. 2388391.
It is known in the specification. The switchgear has fixed and movable contacts, the movable contacts being formed as push rods, which block the beam of the photoelectric barrier when the connection changes.

[0004] DE-A-19547524 consists of fixed and movable contacts, which have elements for adjusting the beam, for example mirrors, which, when coming into contact with a movable counter-contact, are elastically deformed by means of an opening and closing contact piece. The invention relates to an optical monitoring system for high and medium pressure switches to be operated. As a result, the contact pressure is monitored as a target value.

[0005] US Pat. No. 4,692,612 relates to a switching device with contacts movable between two switching positions. To monitor the contact position, a light emitting diode emitting a plurality of colors is provided, which directs the beam to the movable contact surface. A reflected beam is received by a first receiver at a first switching position and by a second receiver at a second switching position.

[0006] Electromechanical switching devices, for example relays or contactors with so-called forced guidance of break and make contacts or contact combinations, are known from the prior art. In this case, the forced guidance means that the open / close contacts of a contact group consisting of at least one break contact and a make contact are mechanically connected so that the break contact and the make contact are not closed at the same time. It is always ensured that a predetermined distance is maintained between the open contacts even in a fault condition. This is guaranteed over the entire life of the switchgear. In particular, even if individual components of the switchgear fail, the nature of the forced guidance of the contacts must be maintained.

The forced guidance prevents the make contact of the forcedly guided switching contact from being seized or otherwise "stuck" by unknown means. In this case, the break contact of the reconnection circuit is not closed, thereby causing a circuit failure.

However, switchgears having forcibly guided switching contacts are expensive to manufacture and more expensive than switchgears without forcibly guided switching contacts.

[0009] Starting from this, the object of the present invention is to provide a switchgear of the type described above in such a way that the same safety can be obtained without mechanical guidance and at the same time the switchgear can be realized inexpensively. It is to improve.

[0010]

Means for Solving the Problems and Effects of the Invention This problem is solved as follows based on the present invention. That is, the optical sensor includes a transmitter for emitting a beam and a photosensitive receiver, and the beam passes through a plane where the contact surfaces of the switching contacts are in contact with each other in a closed connection state of the switching contacts.

According to the present invention, the connection state of each switching contact can be easily monitored by the optical sensor, so that a costly and expensive mechanical connection of the switching contact is not required. The output of the sensor includes a signal that provides information as to whether the monitored switching contact has been properly switched according to the switching signal, or whether the switching operation could not be performed due to a failure. The output signal of the sensor can be appropriately analyzed to initiate or stop subsequent operations.

Optical sensors offer the advantage of operating without wear and guaranteeing a high life even when the switching is frequently alternating. In addition, it has been found that the optical sensor is particularly hard to break down. This allows for use in particular in safety circuits.

As a particular advantage, it must be mentioned that when the switching contact is opened, the beam exiting the transmitter is received unhindered by the photosensitive receiver. The beam is cut off when the switching contact is closed. When the closed contacts fail and do not open, for example, if the contact surfaces burn together due to excessive current flow, the beam remains blocked. When the switchgear is inactive, it results in a fault signal.

The beam emanating from the transmitter of the sensor, which is also preferably formed as a bifurcated photoelectric barrier, can pass through the plane in which the switching contact pins of the switching contact are located in a closed or open connection.

The output of the sensor is connected to a first input of a comparator, preferably a logic circuit, whose second input is an analysis for the switchgear so that the connection state of the switchgear can be defined. Connected to the output of the device. If, for example, there is a logic signal "1" at the output of the control device during normal operation, the break contact must be opened and the make contact must be closed. If the make contact is monitored by a sensor according to the invention, a logic signal "1" will appear at the output of the sensor since the beam is interrupted. Comparison of the two signals by the analyzer will generate a signal "1" at the output. If the switchgear is shut off, the closed make contact must be opened without fault. This means that the signal "0"
It means there is. Comparison with the canceled make signal, also taking the state "0", reveals that a fault free condition exists. However, if there is a different logic state at the input of the analyzer, a fault signal is generated.

The sensor has dynamic operating characteristics so that an emergency failure of the switching contact can be detected. The control of the photoelectric barrier is then effected by means of pulses, which are evaluated at the receiver in relation to the expected value.

Another advantage of the embodiment according to the invention is that since the sensor is electrically isolated from the switching contacts, the potential separation of the switching contacts which is often necessary or preferred for safety technical or functional reasons. It can be seen that-with respect to the connected voltage or load equipment-is maintained.

Depending on the demands on safety technology, the proper operation of the optical sensor can be monitored in a safety-oriented manner. For this purpose, the optical sensor, in particular the bifurcated photoelectric barrier or the reflective photoelectric barrier, is designed to operate in a closed-circuit manner or to perform a supplementary periodic or dynamic self-test.

In a special embodiment, an electromechanical switchgear with a switching contact monitored according to the invention is configured as a safety relay unit. In this case, all switching contacts can be monitored by optical sensors, regardless of the embodiment as make or break contacts. It is also possible to monitor a plurality of make or break contacts juxtaposed with a single forked photoelectric barrier. The beam emanating from the transmitter then passes through the area of the contact surface of the juxtaposed make contacts.

[0020] Other details, advantages and features of the invention are set forth in the following description of preferred embodiments shown in the drawings, as well as in the claims and in the features which are obvious in the claims-not alone or in combination. Is also clear.

[0021]

DETAILED DESCRIPTION OF THE INVENTION An electromechanical switchgear 10 according to the invention, which is designed, for example, as a relay or a contactor and is provided in particular for a safety circuit, for example a safety relay unit, is shown in FIG.
This is shown only schematically. Switchgear 10 has a contact surface 1 at each end
It has at least one mechanical switching contact 12 with switching contact pins 14, 16 having 8,20. The switching contact 12 is operated by an exciting coil 22 connected to a control device 24.

In the present invention, the electromechanical switching device 10 has a sensor 26 for monitoring the connection state of the mechanical switching contact. In the embodiment shown here, the sensor 26 is configured as an optical sensor and comprises a transmitter 28 emitting a beam 30 and a photosensitive receiver 32. The receiver is opposed to the transmitter, and the switching contacts 12
The beam 30 is received in the open state. Transmitter 28 and receiver 32
Is connected to the analyzer 34, the output 36 of which is the comparator
40 is connected to a first input 38. An error signal can be extracted from the output 42 of the comparison device. A second input 44 of the comparison device 40 is connected to an output 46 of the control device 24.

In order to monitor the connection position of the switching contact 12,
As shown in FIG. 2, the beam 30 passes through a plane where the contact surfaces 18 and 20 are in a closed connection state of the switching contact 12.

According to FIG. 1, the switching contact 12 formed as a make contact is in an open connection. Since the control by the control device 24 is not performed, for example, a signal “0” is present at the output 46. In this connection, the beam 30 is incident on the photosensitive receiver 32, so there is a signal "0" at the output of the analyzer 34. If the comparison device 40 is configured as an AND gate, for example,
In this state of use, there is a signal "1" at the output 42 of the comparator.
This indicates proper use. However, if there is a make signal "1" at the output 46 of the control device 24, the switching contact 12 must be in a closed connection state. In that case, the beam 30 is cut off, and as a result, the output of the analyzer 34
36 has a signal "1". Even in this use state, there is a signal “1” at the output 40 of the comparison circuit. This is based on proper operation.

In the event of a fault, for example, a disconnection of the exciting coil 32, the contact pieces 14, 16 do not assume a closed position, and therefore the beam 30 is not interrupted. Since different signals arrive at the inputs 38 and 44 of the comparator 40, a signal "0" appears at the output 42. This indicates a failure.

FIG. 2 shows a case where the contact surfaces 18, 20 of the switching contact 12 are burned to each other. In this case, the excitation coil 22
Is not controlled by the controller 24, so the output 46 has a signal "0". The signal 30 is present at the output 36 of the analyzer 34 because the beam 30 is interrupted due to the burn-in of the contact surfaces 18,20. Therefore, since there are different signals at the inputs 38 and 44 of the comparison device 40, an error signal "0" is generated at the output 42.

FIG. 3 shows a schematic diagram of the switching contact 48 having the contact pins 50 and 52, the connection state of which is monitored by an optical sensor 54 configured as a reflective photoelectric barrier. In that case, the specific reflection of the contact pin 52 having the light reflection layer 56 is used.
The beam 58 is emitted from the sensor 54, enters the light reflecting layer 56, and is reflected from this layer. Depending on the position of the contact pins 52, the beam will be received by the photosensitive receiver integrated into the sensor 54 or not incident on the receiver. Figure 1 shows the signal analysis.
Or according to the embodiment according to 2.

Depending on the requirements of the safety technology, operation is performed in a closed-circuit manner, or by performing supplementary periodic or dynamic self-tests, to monitor the proper operation of the sensors 26, 54 in a safety-oriented manner. can do.

In summary, the invention provides an electromechanical switchgear with optical monitoring of the connection status of the mechanical switchgear, which can be mounted inexpensively on a switchgear with a miniaturized structure and which operates particularly reliably. Provided. Furthermore, in contrast to conventional electromechanical switchgear, the use of sensors 26, 54 with supplementary dynamic operating characteristics makes it possible to detect an accidental breakage of the switching contact, a safety technical advantage. Is born.

[Brief description of the drawings]

FIG. 1 is a diagram of an open connection position of a make contact monitored by a bifurcated photoelectric barrier.

FIG. 2 shows a closed connection position of the make contact according to FIG. 1;

FIG. 3 is a side view of a make contact monitored by a reflective photoelectric barrier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Switching device 12 Switching contact 18 Contact surface 20 Contact surface 26 Optical sensor 28 Transmitter 30 Beam 32 Receiver

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02H 3/04 H02H 3/04 A

Claims (9)

[Claims] An electromechanical switchgear (10) for a safety circuit, for example a safety relay unit, having at least one electrical switching contact (12) whose connection is monitored by an optical sensor (26). ), The optical sensor (26) consists of a transmitter (28) for radiation of the beam (30) and a photosensitive receiver (30), the beam (30) being in the closed connection of the switching contact (12). A switchgear characterized in that the contact surfaces (18, 20) of the switchgear contacts (12) pass through mutually adjoining planes. 2. A beam (30) emanating from a transmitter (28) of a sensor (26), preferably formed as a bifurcated photoelectric barrier, is closed or open, and a switching contact pin (16) of a switching contact (12) is provided. ,14)
Claim 1 characterized by passing through a plane on which
3. The switchgear according to claim 1. 3. The sensor (26, 54) comprises an analyzer (34),
The output (36) of the analyzer (34) is connected to the first input (3) of the comparator (40).
8) and the second input of the comparison device (40) is a switching contact (1
Switchgear according to claim 1 or 2, characterized in that it is connected to the output (46) of the control device (24) for (2, 48). 4. The switchgear according to claim 1, wherein the sensors have dynamic operating characteristics. 5. The switching device according to claim 1, wherein the sensors are electrically separated from the switching contacts. 6. The electric switchgear (10) has a safety-oriented monitoring device for the sensors (26, 54), and the optical sensors (26, 54) are controlled in a closed-circuit manner or, additionally, periodically or dynamically. The switchgear according to any one of claims 1 to 5, wherein a dynamic test is performed. 7. The switchgear according to claim 1, wherein the electromechanical switchgear is configured as a safety relay unit. 8. The switching device according to claim 1, wherein the electromechanical switching contact is formed as a break contact or a make contact or as a contact combination. 9. A method according to claim 1, wherein a plurality of preferably juxtaposed make or break contacts are monitored by a single optical sensor. The switchgear according to any one of the above.