DK2416339T3

DK2416339T3 - Self-monitoring pressure switch and accompanying monitoring method

Info

Publication number: DK2416339T3
Application number: DK11174894.3T
Authority: DK
Inventors: Manfred Zmeck
Original assignee: Schaefer Gmbh
Priority date: 2010-08-04
Filing date: 2011-07-21
Publication date: 2016-12-05
Also published as: CN102376148A; DE102010036838A1; EP2416339A3; EP2416339B1; EP2416339A2; CN102376148B; ES2602837T3; PL2416339T3

Description

Self-Monitoring Button Switch Circuit and associated Monitoring Method

The invention relates to a self-monitoring button switch circuit, which is suitable for example as an emergency alarm, and to a method for self-monitoring of a corresponding button switch circuit. DE 36 42 231 A1 discloses a device for self-monitoring of relay contacts. This device comprises two relays with changeover contacts, the normally closed contacts of which are connected to one another in series. The series circuit supplies the light-emitting diode of an optocoupler. Even if only one of the relay contacts switches over, the light-emitting diode of the optocoupler goes out.

In many technical applications, it is necessary to ensure that a particular signal, which may for example be triggered by a person by actuating a switch, is detected reliably and forwarded to a message device. In order to genuinely ensure reliability of the system, functionality of the signal transmission path must be guaranteed.

It is therefore an object of the invention to provide a concept with which the functionality of a tester device is ensured.

This object is achieved with a button switch circuit according to Claim 1 and with a method according to Claim 10:

The concept according to the invention proposes that a suitable button switch circuit should monitor its own functionality. To this end, the button switch circuit is divided into two part circuits, each of which controls a relay. A normally closed contact of one relay is connected in series with a first normally open contact of the other relay. The two contacts connected in series are connected to a message circuit. The latter determines a closed current loop due to the two contacts connected in series. The same current loop is used for the signal transmission for button or actuation signals. If the button switch circuit detects an actuation signal at a sensor input, preferably only one of the two relays is switched over at least temporarily, so that the message circuit detects opening of the current loop and therefore generates a corresponding signal, for example an alarm signal.

For self-monitoring, provision is made that at least one of the two part circuits activates the other respective part circuit from time to time in the sense that the two relays switch over essentially simultaneously. The message current loop therefore remains closed. If the simultaneous switching over of the two relays is not successful because of some fault, however, the message current loop is broken, so that the message circuit can detect a fault signal and generate an alarm signal.

In other words, the button switch circuit consists of two part circuits, which monitor each other's function by one part circuit from time to time, for example cyclically, sending the other part circuit a command to switch over the relay on the output side, and simultaneously switches over its own relay on the output side. The relays preferably comprise a normally open contact (make contact) and a normally closed contact (break contact). Whether or not the relay switches over can in this case be detected with great reliability because the simultaneous closing of a break contact and a make contact can be ruled out with high probability.

Other fault scenarios, for example an operating voltage failure at the button switch, can thus also be detected reliably because this leads to current interruption in the message current loop as a result of opening of the normally closed contact of the series circuit. Preferably, to this end, in the normal state of the button switch circuit one of the relays is in the picked-up state and the other of the relays is in the dropped-out state.

The connected message device is preferably configured in such a way that it only evaluates signals that are longer than a minimum switching time. The switching delay of the relay is preferably shorter than the minimum switching time. The duration of the test, i.e. of the switching command, is preferably longer than the minimum switching time. In this way, it is possible to avoid triggering of false alarms because of the test sequence being carried out.

Furthermore, the short-term breaking of the message current loop when carrying out the test sequence is additionally monitored, and is evaluated as an indication of the functionality of the button switch and of the message current loop.

The button switch circuit according to the invention suitable, in particular, for monitoring contactless capacitive button switches. The instruction to switch a part circuit over is carried out in the scope of a test sequence, preferably by a capacitance change at the sensor input. In this way, all functionally required components are included in the monitoring, and the functionality of the button switch circuit is checked reliably within the test sequence.

Further details and advantageous embodiments of the button switch circuit or of the method for function monitoring of a button switch, and other details of the concept according to the invention, may be found in the figures, the description and dependent claims.

Figure 1 shows a button switch in the operating state without actuation as a block diagram.

Figure 2 shows the button switch circuit according to Figure 1 in the actuated state,

Figure 3 shows the button switch circuit according to Figure 1 during cyclic function monitoring in the case of correct function,

Figure 4 shows the button switch circuit during the function check when there is a malfunction, and

Figure 5 shows a further embodiment of the button switch circuit according to the invention as a block diagram, in the non-actuated operating state.

Figure 1 illustrates a button switch 10, which comprises a sensor surface 11 and a button switch circuit 12. The sensor surface 11 is connected to a sensor input 13 of the button switch circuit 12, which input is used to detect whether or not the sensor surface 11 is being touched by an operating person. Instead of the sensor surface 11, however, it is also possible to use other signal input means, for example switches, optical sensors or the like.

The button switch circuit 12 comprises at least two part circuits 14, 15, which may for example be formed on a common printed circuit board or spatially separately from one another. For example, the two part circuits 14, 15 may be formed by, or contain, separate circuit blocks, for example separate microprocessors.

The first part circuit 14 detects the capacitance connected to the sensor input 13. If this capacitance increases significantly, this is evaluated as touching of the sensor surface 11 by an operator, and correspondingly drives a connected first relay 16. A second relay 17 is connected to the second part circuit 15.

The first relay 16 comprises a first changeover contact 18. The second relay 17 comprises a second changeover contact 19.

The first changeover contact 18 has a first normally closed contact 20 and a first normally open contact 21.

The second changeover contact 19 has a second normally closed contact 22 and a second normally open contact 23.

The term "normally closed contact" is used synonymously with the term "break contact". The term "normally open contact" is used synonymously with the term "make contact". In the button switch circuit 12 according to Figure 1 and in all other circuits described below, the first normally closed contact 20 and the second normally open contact 23 are connected to one another. Furthermore, the first normally open contact 21 and the second normally closed contact 22 are connected to one another. The series circuit formed in this way is part of a message current loop 24, which is connected to a message circuit 25. The message circuit 25 may be part of the button switch circuit 12. Preferably, however, it is arranged away from the part circuits 14, 15, at the place where a signal that indicates actuation of the button switch 10 is intended to be output or generated. The message circuit 25 may be arranged at a large distance from the button switch circuit 12 and connected thereto by means of the two-wire line 26.

It permanently monitors the message current loop 24 for continuity, for example by a continuous flow of current being maintained in the message current loop 24.

The second part circuit 15 may be provided with a timer which initiates a self-test routine from time to time, for example at fixed time intervals (i.e. cyclically). Such a self-test routine may be carried out at relatively long time intervals, for example at an interval of several hours, for example 24 hours, and may respectively last from one to a few seconds. In order to carry out the self-test, a device for test signal generation is connected to the sensor input 13. In the present exemplary embodiment, this is a capacitor 27 which is connected in series to ground by a controllable switch 28, for example a transistor. The control input of the switch 28 is connected to one of the part circuits 14, 15, for example the part circuit 15. In this case, a timer provided in the part circuit 15 initiates a test process from time to time, as explained above. The part circuit 15 is configured in order to simultaneously close the switch 28 and switch over the relay 17. In the case of an intact part circuit 14, closing of the switch 28 causes switching of the relay 16.

For further functional monitoring, the part circuit 14 may contain a further timer, which is set for a time that is longer than the time of the timer in the part circuit 15. For example, the time set in the timer of the part circuit 14 may be 26 hours if the time set in the timer of the part circuit 15 is 24 hours. If the timer in the part circuit 14 determines that the test signal of the part circuit 15 is absent during the aforementioned 26 hour sequence, the part circuit 14 may be configured in order to switch over the relay 16. The timers may be formed by program routines inside the part circuits 14 and 15, if the part circuits 14, 15 contain correspondingly programmable means, for example a microcontroller.

The button switch circuit 12 described above operates as follows:

The button switch circuit 12 represented in Figure 1 is in the correct operating state. The two part circuits 14, 15 are supplied with voltage by an operating voltage supply (not further illustrated). In this state, one of the relays 16, 17 is picked up and the other is dropped out. In the present exemplary embodiment, for example, the relay 16 may be in the resting state (de-energised) while the relay 17 is powered (energised). The message current loop 24 is closed by means of the normally closed contact 20 and the normally open contact 23. The message circuit 25 therefore determines that there is integrity of the message current loop 24 and does not generate an alarm signal.

Figure 2 illustrates the function of the button switch 10 and of its button switch circuit 12 in the event of actuation by an operating person 29 touching the sensor surface 11. At the sensor input 13, the part circuit 14 now detects an increased capacitance, and consequently switches over the first relay 16. The normally closed contact 20 opens, while the normally open contact 21 closes. The part circuit 15, however, does not switch over the relay 17 connected to it. As a result of this, the message current loop 24 is broken. The message circuit 25 detects this and generates an alarm 30, which is indicated symbolically in Figure 2 and may, for example, be an optical, acoustic or other signal.

Figure 3 illustrates the running of a self-test sequence of the button switch 10, or of its button switch circuit 12. The self-test sequence is, for example, initiated by the timer of the part circuit 15, by the latter closing the switch 28, for example for a few seconds, for example 5 seconds. The sensor input 13 of the first part circuit 14 is therefore loaded for this time with the capacitance of the capacitor 27 (for example a few tens of 10 pF). From the point of view of the part circuit 14, this corresponds to touching of the sensor surface 11. The first part circuit 16 therefore switches over the relay 16. The part circuit 15 likewise switches over the second relay 17 which is connected to it. As a result of this, the message current loop 24 is closed via the first normally open contact 21 and the second normally closed contact 22. Correct function both of the part circuit 15 and of the part circuit 14 therefore leads to switching of the two relays 16, 17 and therefore not to the generation of a fault signal in the message circuit 25, which is indicated by a "0". No alarm signal is generated.

Figure 4 illustrates the state during a test sequence when one of the part circuits, for example the first part circuit 14, is not operating correctly. The relay 16 therefore does not switch over - it remains in its closed position which it has in Figure 1. Its first normally closed contact 20 remains closed. Owing to the initiation of the test sequence, however, the second relay 17 switches over. Its second normally open contact 23 opens. The normally closed contact 22 closes. This means breaking of the message current loop 24 and therefore response of the message circuit 25. The latter now generates an alarm signal.

The situation is similar when the part circuit 15 rather than the part circuit 14 contains a fault. Again, opening of the message current loop then takes place.

If the first part circuit 14 detects that a signal remains at its sensor input 13 for a period of time which is (significantly) longer than the duration specified by the part circuit 15 for carrying out self-checks, it may likewise be programmed to switch over the relay 16 and therefore trigger alarm signal generation.

In the function descriptions above, it was tacitly assumed that the two relays 16, 17 switch over simultaneously. In fact, however, it is preferred to switch over the two relays 16, 17 with a certain time offset, for example half a second, but in any event a time offset which is significantly shorter than the duration of the test process, or test sequence. The message circuit 25 may then detect a brief temporary break of the message current loop 24, which for example last half a second. The message circuit 25 is in this case preferably configured in order to evaluate a break of the message current loop 24 as a signal indicating actuation of the button switch circuit 12 only when the break of the message current loop 24 last longer than this period of time (for example half a second). Furthermore, the message device may be configured in order to generate a fault signal when such a very brief break of the message current loop does not take place for a period of time which is longer than the period set by the part circuit 15 for carrying out test cycles (for example 24 hours).

The part circuit 14 may be configured in such a way that it switches the relay 16 over for a relatively long time, for example at least 5 seconds, when the sensor surface 11 has been touched at least briefly by an operator. In this way, the message circuit 25 reliably detects touching of the sensor surface 11, and evaluates it as a fault signal, even if the sensor surface 11 has only been tapped briefly.

The relays 16, 17 may comprise further contacts (not represented) for controlling further current loops. These may be break contacts, make contacts, changeover contacts or the like.

Furthermore, as illustrated in Figure 5, the button switch circuit 12 may contain additional relays, for example a relay 30 which is for example controlled by the part circuit 14. The relays 16 and 30 may operate simultaneously or with a slight time offset. The relay 17 may have one or more further contacts 31 in addition to the changeover contact 19. For example, the part circuits 14, 15 may be configured in order to switch over the relays 17 and 30 exactly simultaneously, for example in order to keep an existing current path 32 permanently free of interruption. In other regards, the part circuit 12 according to Figure 5 may operate according to the function as described in connection with Figures 1 to 4.

The button switch circuit 25 according to the invention consists of two part circuits 14, 15, which monitor each other's function. This is done by one of the part circuits 14, 15 cyclically activating the other respective part circuit, for example by generating a test signal. The test signal may, for example, be performed by applying a test signal to the sensor input 13 of relevant part circuit 14. The two part circuits 14 and 15 respectively control a relay 16, 17. Preferably, one of the relays 16, 17 is powered in the resting state, while the other of the two relays 16, 17 is currentless in the resting state. A normally closed contact of one relay is connected in series with the normally open contact of the other relay, so as to form a current loop which is permanently closed (or alternatively permanently open) both in normal operation and during the test sequence. The integrity of the current loop is monitored by a message circuit 25. Signalling of actuation of the button switch, as well as of failure of the button switch circuit 12, are respectively carried out by breaking (or closing) of the message current loop 24.

List of References: 10 button switch 11 sensor surface 12 button switch circuit 13 sensor input 14 first part circuit 15 part circuit 16 first relay 17 second relay 18 first changeover contact 19 second changeover contact 10 first normally closed contact 21 first normally open contact 22 second normally closed contact 23 second normally open contact 24 message current loop 25 message circuit 26 two-wire line 27 capacitor 28 switch 29 operating person 30 third relay

Claims

1. Selv-overvågende trykknapskredsløb (12), med et første delkredsløb (14) forbundet med et første relæ (16) der har en første skiftekontakt (18) omfattende en første hvilekontakt (20) og en første arbejdskontakt (21), med et andet delkredsløb (15) forbundet med et andet relæ (17) der har en anden skiftekontakt (19) omfattende en anden hvilekontakt (22) og en anden arbejdskontakt (23), hvor mindst et af de to delkredsløb (14, 15) har en sensorindgang (13), kendetegnet ved at den første arbejdskontakt (21) er serieforbundet med den anden hvilekontakt (22) og den første hvilekontakt (20) er serieforbundet med den anden arbejdskontakt (23), med et signalkredsløb (25) forbundet med et signalstrømkredsløb (24) som omfatter seriekredsløbene dannet af arbejdskontakterne (21; 23) og hvilekontakterne (20; 22) og som, når en strømafbrydelse opdages, danner et fejlsignal i signalstrømkredsløbet (24).A self-monitoring pushbutton circuit (12), with a first subcircuit (14) connected to a first relay (16) having a first switching contact (18) comprising a first resting contact (20) and a first working contact (21), with a a second subcircuit (15) connected to a second relay (17) having a second switching contact (19) comprising a second resting contact (22) and a second working contact (23), wherein at least one of the two subcircuits (14, 15) has a sensor input (13), characterized in that the first working contact (21) is connected in series with the second resting contact (22) and the first resting contact (20) is connected in series with the second working contact (23), with a signal circuit (25) connected to a signal current circuit (24) which comprises the series circuits formed by the working contacts (21; 23) and the resting contacts (20; 22) and which, when a power failure is detected, generate an error signal in the signal current circuit (24).

2. Trykknapskredsløb ifølge krav 1, kendetegnet ved at det første relæ (16) og det andet relæ (17) holdes i forskellige tilstande når trykknapskredsløbet (12) er i ventetilstand.Pushbutton circuit according to claim 1, characterized in that the first relay (16) and the second relay (17) are held in different states when the pushbutton circuit (12) is in the waiting state.

3. Trykknapskredsløb ifølge krav 1, kendetegnet ved at sensorindgangen (13) er en kapacitetsmålingsindretningsindgang.Push-button circuit according to claim 1, characterized in that the sensor input (13) is a capacity measuring device input.

4. Trykknapskredsløb ifølge krav 1, kendetegnet ved at sensorindgangen (13) er forbundet med en kondensator (27) der er serieforbundet med en kontrollerbar kontakt (28).Push-button circuit according to claim 1, characterized in that the sensor input (13) is connected to a capacitor (27) connected in series with a controllable switch (28).

5. Trykknapskredsløb ifølge krav 4, kendetegnet ved at kontakten (28) har en kontrolindgang som er forbundet med et af delkredsløbene (15).Push-button circuit according to claim 4, characterized in that the switch (28) has a control input connected to one of the sub-circuits (15).

6. Trykknapskredsløb ifølge krav 1, kendetegnet ved at et af de to delkredsløb (14, 15) er konfigureret til at starte et rutinetjek en gang imellem.Push-button circuit according to claim 1, characterized in that one of the two sub-circuits (14, 15) is configured to initiate a routine check once in a while.

7. Trykknapskredsløb ifølge krav 5 og 6, kendetegnet ved at som del af rutinetjekket, lukkes kontakten (28) for at skifte relæet (16) forbundet med det pågældende delkredsløb (14), hvor det andet relæ (17) skiftes på samme tid.Push-button circuit according to claims 5 and 6, characterized in that as part of the routine check, the switch (28) is closed to change the relay (16) connected to the respective sub-circuit (14), where the second relay (17) is switched at the same time.

8. Trykknapskredsløb ifølge krav 6, kendetegnet ved at der tilvejebringes fastsatte tidsintervaller til at udløse rutinetjekket.Push-button circuit according to claim 6, characterized in that fixed time intervals are provided for triggering the routine check.

9. Trykknapskredsløb ifølge krav 8, kendetegnet ved at det andet delkredsløb (15) er konfigureret til at skifte dets angivne relæ (17) hvis det ikke modtager noget indgangssignal i løbet af et forudbestemt tidsrum der er længere end tidsintervallet til at udløse rutinetjekket.Push-button circuit according to claim 8, characterized in that the second sub-circuit (15) is configured to switch its specified relay (17) if it receives no input signal during a predetermined period longer than the time interval for triggering the routine check.

10. Fremgangsmåde til funktionsovervågning af en trykknap (10) med et trykknapskredsløb (12) ifølge krav 1, kendetegnet ved at et af de to delkredsløb (15) skifter det forbundne relæ (17) fra tid til anden og samtidigt simulerer et aktiveringssignal ved sensorindgangen (13) for at bevirke at det andet delkredsløb (14) også skifter relæet (16) forbundet dermed, hvori i løbet af dette, signalkredsløbet (25) overvåger samtidig eller forskudt skift af de to relæer (16, 17).Method for function monitoring of a pushbutton (10) with a pushbutton circuit (12) according to claim 1, characterized in that one of the two subcircuits (15) switches the connected relay (17) from time to time and simultaneously simulates an activation signal at the sensor input (13) to cause the second subcircuit (14) to also switch the relay (16) associated therewith, during which, the signal circuit (25) monitors simultaneously or offset shifting of the two relays (16, 17).