EP0109696B1 - Circuit de sécurité pour un système - Google Patents

Circuit de sécurité pour un système Download PDF

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Publication number
EP0109696B1
EP0109696B1 EP83201384A EP83201384A EP0109696B1 EP 0109696 B1 EP0109696 B1 EP 0109696B1 EP 83201384 A EP83201384 A EP 83201384A EP 83201384 A EP83201384 A EP 83201384A EP 0109696 B1 EP0109696 B1 EP 0109696B1
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EP
European Patent Office
Prior art keywords
relay
capacitor
control relay
contact
contacts
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83201384A
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German (de)
English (en)
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EP0109696A1 (fr
Inventor
Cornelis Arend Vreugdenhil
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
VEG-GASINSTITUUT NV
Veg Gasinstituut NV
Original Assignee
VEG-GASINSTITUUT NV
Veg Gasinstituut NV
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Application filed by VEG-GASINSTITUUT NV, Veg Gasinstituut NV filed Critical VEG-GASINSTITUUT NV
Priority to AT83201384T priority Critical patent/ATE27732T1/de
Publication of EP0109696A1 publication Critical patent/EP0109696A1/fr
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/20—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays
    • F23N5/203—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/28—Ignition circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2229/00—Flame sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2231/00—Fail safe
    • F23N2231/06—Fail safe for flame failures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2231/00—Fail safe
    • F23N2231/12—Fail safe for ignition failures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves

Definitions

  • the invention relates to a circuit for fail safe control of a system, comprising a command switch, a control relay, an auxiliary relay and a capacitor, which capacitor after closing of the command switch can be charged from a power supply source to a predetermined voltage before the control relay is energized, which control relay is energized through an energizing path containing at least one contact of the auxiliary relay and is maintained in the energized state through a contact of the control relay.
  • a circuit of this type is described in the US Patent 4,116,613.
  • a first capacitor 37 is used to determine a first delay period necessary for charging a further capacitor 61 in a timing circuit 28. If the capacitor 37 is charged to a sufficient level and if simultaneously the capacitor 61 is charged to a sufficient level then the relay R2 is energized through a transistor 35. Through the switched-over contacts R2A and R2B the capacitor 61 is then connected to a flame sensing circuit 16. Thereby the capacitor 61 functions as voltage source to the electronic circuit which, through the unijunction transistor 44 causes the energizing of the relay R1. However, the capicator 61 does not form the actual energizing source for the relay R1. The energizing current is supplied by a transformer T1.
  • the energizing path of the relay R1 comprises a switch WS of which the contacts will switch over in case within a predetermined period the pilot flame is not ignited.
  • the relay R1 is directly energized after the switching of the command contact THS.
  • the delay circuit 22 comprises also in this case a capacitor 27 which has to be charged before the relay R3 is able to become energized.
  • the flame detection circuit 20 is almost identical to the corresponding circuit in the above mentioned US Patent 4,116,613. Only the time determining circuit 28 is deleted and replaced by a circuit with the transistor 50, which circuit comprises a contact of the relay R3.
  • An object of the invention is now to provide a fail safe circuit in which the status of the contacts of each used relay is checked.
  • the invention now provides a circuit of the type described in the first paragraph, characterized in that the capacitor C1 is charged through at least a normally closed contact of the control relay AR and after energizing of the control relay said capacitor C1 is connected to the auxiliary relay HR through at least one of the now switched over contacts of said control relay AR and forms during a predetermined period the only voltage source for said auxiliary relay, energizing said auxiliary relay.
  • the auxiliary relay can only be energized if the precharged capacitor becomes connected to said auxiliary relay. Said capacitor, however, can only become charged after closing of the command switch if the control relay contact is in the normal position. Furthermore, operation of the control relay is only possible if the contact of the auxiliary relay, connected into the energizing path of the control relay, is initially in the normal state. If these start conditions are not fulfilled, in other words if e.g. one of said contacts is welded into the activated state, then it is impossible to charge the capacitor for to connect the charged capacitor to the auxiliary relay. In that case the auxiliary relay will not become operated thereby inhibiting further operation of the system.
  • the figures 1,2, and 3 illustrate three variants of the circuit according to the invention.
  • Figure 4 illustrates an embodiment if the circuit according to the invention in which relais of the so-called forced guidance type are used.
  • FIG. 5 illustrates another embodiment of the circuit according to the invention in which normal relais is used.
  • FIGS 6 and 7 illustrate embodiment of the circuit according to the invention in which an air pressure responsive switch is used.
  • FIGS 8, 9, and 10 illustrate applications of the invention in burner control circuits.
  • the power supply voltage of the circuit illustrated in fig. 1 in many cases the mains voltage, is supplied to the terminals 1 and 2 and is rectified by the diode D1.
  • the resulting DC voltage is used to supply the control relay AR and to load the capacitor C1.
  • the diode D2 bridges the second half period into which no current flows and functions furthermore, just as the diode D3 which is connected parallel to the auxiliary relay HR, to extinguish the self-inductance voltage appearing when the relay AR respectively HR is de-energized.
  • a command switch RT is connected between the terminals 3 and 4. Between the terminals 4 and 2 the start condition circuit is connected comprising a series circuit of a contact HR1 of the auxiliary relay HR and a contact AR3 of the control relay AR, and furthermore the already mentioned rectifying diode D1, a pair of current limiting resitors R1 and R2 and the control relay AR with the already mentioned diode D2 parallel therewith.
  • a holding path for the relay AR extends from the terminal 4 through the contact AR1, the diode D6 and the resistor R3.
  • the junction between AR1 and D6 is connected to the normally open contact of AR3.
  • the auxiliary relay HR is through the diode D4 connected to the normally open contact of HR1.
  • the capacitor C1 can be connected through the contact AR4 either to the junction between R1 and R2 or through D5 to the auxiliary relay HR.
  • the energizing path for the relay AR between the terminals 4 and 2 can only become closed if both the contact HR1 as well as AR3 are closed, in other words if both relais AR and HR are not energized and both mentioned contacts are in the normal position.
  • the capacitor C1 will become charged through D1 and R1. Initially, the uncharged capacitor will cause such a low voltage over R2 and AR that operation of AR is prevented. If the capacitor however becomes charged to a sufficiently high voltage, then AR is operated and the contacts AR1, AR3 and AR4 will switch into the other operating state. A relatively small capacitor C2 is connected parallel to the relay AR to prevent that the relay AR as a result of the switching of the contact AR3 releases immediately.
  • the contact AR1 forms the holding path for maintaining the relay AR energized through D6 and R3 as long as the command switch RT is closed and irrespective of the further position of the contacts HR1 or AR3.
  • the contact AR4 switches over to the other state the now charged capacitor C1 is through D5 connected to the terminals of the auxiliary relay HR.
  • the values of R1, R2 and C1 should be selected such that on the one hand the capacitor C1 can become charged before especially contact AR4 switches over and on the other hand the capacitor C1 has to be charged such that the auxiliary relay HR can become energized during a sufficiently large period during the discharging of this capacitor C1 to bridge the switching operation of HR.
  • the capacitor C1 will, after switching of the contact AR4, function as voltage source for the auxiliary relay HR, energizing said relay. Therefore, the contact HR1 will switch to the other position so that through the already switched contact AR3 and through HR1 and D4 a holding path for the auxiliary relay HR is formed, with the result that HR maintains energized even if in the meantime C1 is discharged.
  • the resistor R3 is present to prevent a rapid charging of the capacitor C1 and thereafter energizing of AR in the very unlikely case that AR1 was welded and R2 is short-circuited.
  • the resistance of R3 is preferably equal to that of R1 + R2.
  • R3 is eliminated because it is presumed that resistors are used which are resistent to short-circuiting.
  • the power supply voltage of the circuit illustrated in fig. 2 in many cases the mains voltage, is again supplied to the terminals 1 and 2 and is rectified by the diode D1.
  • the resulting DC voltage is used to supply the control relay AR and to charge the capacitor C1.
  • the diode D2 bridges the second half period into which no current flows and functions furthermore, just as the diode D3 which is connected parallel to the auxiliary relay HR, to extinguish the self-inductance voltage appearing when the relay AR respectively HR is de-energized.
  • a command switch RT is connected between the terminals 3 and 4.
  • the start condition circuit is connected comprising a series circuit of the contacts S1 and S2 of the switching relais S, a contact HR1 of the auxiliary relay HR and a contact AR3 of the control relay AR, and furthermore the rectifying diode D1, a pair of current limiting resistors R1 and R2 and the control relay AR with the diode D2 parallel therewith.
  • a small capacitor C2 is connected parallel to the control relais.
  • a series circuit of contacts AR1 and AR2 is connected parallel to contacts S2 and S1, whereby the junction between AR1 and AR2 is connected on the one hand to the control relais AR through D6 and on the other hand to the make contact terminal of AR3.
  • the make contact terminal of S2 and the make contact terminal of HR1 are both connected to relais S.
  • the auxiliary relay HR is on the one hand connected to terminal 2 and can be connected through the change over contact AR4 to the capacitor C1 of which the other side is connected to terminal 2.
  • the energizing path for the relay AR between the terminals 4 and 2 can only become closed if both the contacts S1 and S2, the contact HR1 as well as AR3 are closed, in other words if none of the relais AR, HR and S is energized and contacts thereof are in the normal position.
  • the values of R1, R2, and C1 should be selected such that on the one hand the capacitor C1 can become charged before especially contact AR2 switches over and on the other hand the capacitor C1 has to be charged such that the auxiliary relay HR can become energized during a sufficiently large period during the discharging of this capacitor C1 to activate relais S.
  • S1 can be replaced by any security or protection means to be tested, for instance in the form of a limit switch.
  • Figure 3 illustrates a third embodiment of the circuit according to the invention of which a large part is identical to the circuit of figure 2.
  • the differences can be traced around HR1 and S1 and the possible connections to HR through the circuits a and b.
  • the start condition circuit comprises in this case the series circuit of HR1, S2 and AR3, connected to the rectifying diode D1, the current limiting resistors R1 and R2, and the control relay AR with parallel thereto again the diode D2.
  • a series circuit of contacts AR1 and AR2 is connected in parallel to HR1, whereby the junction of said series circuit is on the one hand through D6 connected to AR and on the other hand connected to the make contact terminal of AR3.
  • the make contact terminal of S2 is connected to the output U and can become connected through circuit b to HR.
  • the make contact terminal of HR1 is connected to the switching relay S and can become connected to the auxiliary relay HR through circuit a.
  • the diodes D4 and D5 are again used for preventing currents in false directions.
  • a small capacitor C2 is connected parallel to the relay AR.
  • the energizing path for the relay AR between the terminals 4 and 2 can only become closed if the contact HR1, the contact S2 as well as AR3 are closed, in other words in case none of the relais AR, HR and S is energized and the contacts thereof are in the normal position.
  • the capacitor C1 will become charged through D1 and R1. Initially the unloaded capacitor will cause such a low voltage over R2 and AR that operation of AR is prevented. If the capicitor however becomes charged to a sufficiently high voltage, then AR is operated and the contacts AR1, AR2, AR3 and AR4 will switch into the other position.
  • the contact AR1 forms the holding path for maintaining the relay AR energized as long as the command switch RT is closed and irrespective of the further state of the contacts HR1 or S2.
  • the contact AR4 connects the now charged capacitor C1 to the terminals of the auxiliary relay HR.
  • the values of R1, R2 and C1 should be selected such that on the one hand the capacitor C1 can become charged before especially contact AR2 switches over and on the other hand the capacitor C1 has to be charged such that the auxiliary relay HR can become energized for a predetermined period during the discharging of this capacitor C1.
  • the switching relais S will be energized through contact HR1 and the now closed contacts AR1 and AR2, so that S2 switches over.
  • the power supply voltage of the circuit illustrated in fig. 4 in many cases the mains voltage, is again supplied to the terminals 1 and 2 and is rectified by the diode D1.
  • the resulting DC voltage is used to supply the control relay AR and to charge the capacitor C1.
  • the diode D2 bridges the second half period into which no current flows and functions furthermore, just as the diode D3 which is connected parallel to the auxiliary relay HR, to extinguish the self-inductance voltage appearing when the relay AR respectively HR is de-energized.
  • a command switch RT is connected between the terminals 3 and 4. Between the terminals 4 and 2 the start condition circuit is connected comprising a series circuit of a contact HR1 of the auxiliary relay HR and a contact S1 of the switching relay S, and furthermore the already mentioned rectifying diode D1, a pair of current limiting resistors R1 and R2 and the control relay AR with the already mentioned diode D2 parallel therewith.
  • the contact HR2 is at the other side connected to the switching relay S of which the other side is connected to terminal 2.
  • the contact S2 is through a further contact S3 connected to relay S.
  • the auxiliary relay HR is connected on one side to the terminal 2 and can become connected with the other side through the switch over contact AR2 to the capacitor C1 of which the other side is connected to terminal 2.
  • the contact AR2 closes the path from the junction between the resistors R1 and R2 through the capicitor C1 to the terminal 2.
  • the capacitor C1 will become charged through D1 and R1. Initially the unloaded capacitor will cause such a low voltage over R2 and AR that operation of AR is prevented. If the capacitor however becomes charged to a sufficiently high voltage, then AR is operated and the contacts AR1 and AR2 will switch into the other position.
  • the contact AR1 forms the holding path for maintaining the relay AR energized as long as the command switch RT is closed and irrespective of the further position of the contacts HR1 or S1. Because the contact AR2 switches over to the other position the now charged capacitor C1 is connected to the terminals of the auxiliary relay HR.
  • R1, R2 and C1 should be selected such that on the one hand the capacitor C1 can become charge before especially contact AR2 switches over and on the other hand the capacitor C1 has to be charged such that the auxiliary relay HR can become energized for a predetermined period during the discharging of this capacitor C1.
  • the capacitor C1 will, after switching of the contact AR2, function as voltage source for the auxiliary relay HR, energizing said relay.
  • the contact HR1 will open which has however no influence anymore because contact AR1 is closed in the meantime and furthermore HR2 will become closed energizing the switching relay S.
  • the relay S should become activated through AR1 and the now closed contact HR2. If the relay S is energized then through AR1, the then closed contacts S2 and S3 a holding path of said relay S is built up, so that S will be maintained in the energized condition even if HR becomes de-energized.
  • the output U of the circuit, to which switching means of the control system are connected, is now through S2, AR1, and RT connected to the power supply terminal 1.
  • relais of the so-called forced guidance type should be used, that means relais of which all contacts are simultaneously in the one or in the other position. If for instance for some reason one of the contracts would become welded into the made position, then in this type of relais all the other contacts are maintained in the made position even if the energizing current through the relay coil is switched off.
  • FIG 4 a further variant is indicated comprising the switch over contact S1' which can be installed instead of S1, and which can be used for connecting the output U' instead of U. In that case one of the contacts S2 or S3 can be eliminated.
  • any security or protection device to be tested can be included into the start condition circuit, e.g. a limit switch.
  • the security or protection means to be tested can be inserted e.g. between the common contact terminal of S1 (or S1') and D1.
  • Figure 5 illustrates an embodiment into which all relais contacts are included into either the energizing path for the control relay AR or into the charging path of the capacitor C1.
  • the contacts AR1, S1, S2 and AR4 are included into the energizing path for the control relay AR.
  • the diode D1 is used again for rectifying the AC voltage and the resistor R2 is used together with the capacitor C2 for determining a delay period before the relay AR will become energized.
  • the diode D2 has just as the diode D3 the same function as the corresponding diodes D2, D3 in the preceding figures.
  • the capacitor becomes charged to a sufficiently high voltage to energize the relay AR, then the contacts AR1, AR2 and AR3 will switch over the charging of the capacitor C1 is e vded.
  • the amount of charge into C1 depends the efor onto the values of R1, C1, R2 and C2.
  • the capacitor C1 is connected as voltage sou ' ce to the auxiliary relay HR, which will becomne energized so that the contact HR1 switches over. Thereafter the switching relay S can become energized through the contacts HR1 and AR3 within the period into which the capacitor C discharges through the auxiliary relay HR. If the switching relay S becomes energized then a holding path is formed through AR2, AR4 and S2.
  • the series circuit of the command switch RT, a contact HR1 of the auxiliary relay HR, a switching contact LD2 of some switching means, the rectifying diode D1, a pair of current limiting resistors R1 and R2 and the control relay AR with the diode D2 parallel thereto is connected between the terminals 1 and 2.
  • a normally open contact AR1 of the control relay AR is connected parallel to the series circuit of the contact HR1 and said contact LD2 of the switching means.
  • the auxiliary relay HR is with the one side connected to terminal 2 and can be connected with the other side through the switch over contact AR2 to the capacitor C1 of which the other side is connected to terminal 2.
  • the contact AR2 forms a path from the junction between the resistors R1 and R2 through the capacitor C1 to the terminal 2.
  • the voltage, supplied to the auxiliary relay HR is rectified by the diode D4.
  • the supply voltage for said auxiliary relay HR can be supplied through a circuit a, through which circuit a connection is realized to the terminal 1 in case the command switch RT is closed and the contact HR1 is switched over into the other position.
  • the voltage for the auxiliary relay can be supplied through circuit b, which circuit can be connected with terminal 1 in case both the control relay contact AR1 as well as the contact LD2 of the switching means are switched over.
  • One side of the circuit b is furthermore connected to the output U.
  • the diode D5 is inserted to prevent false charging of the capacitor through one of the circuits a or b. If this possibility is not real then D5 can be eliminated.
  • the circuit illustrated in figure 6 can be used e.g. for controlling a system comprising a ventilator M which is indicated in figure 6.
  • the switching means related to that ventilator is e.g. embodied as a means reacting onto air pressure or air current, e.g. a switch LD2 responding to a predetermined minimum air pressure.
  • the capacitor C1 will become charged through D1 and R. Initially the unloaded capacitor will cause such a low voltage over R2 and AR that operation of AR is prevented. If the capacitor however becomes charged to a sufficiently high voltage, then AR is operated and the contacts AR1 and AR2 will switch over into the other position.
  • the contactAR1 forms the holding path for maintaining the relay AR energized as long as the command switch RT is closed and irrespective of the further state of the contacts HR1 and LD2. Because the contact AR2 switches over to the other position the now charged capacitor C1 is connected to the terminals of the auxiliary relay HR.
  • R1, R2, and C1 should be selected such that on the one hand the capacitor C1 can become charged before especially contact AR2 switches over and on the other hand the capacitor C1 has to be charged such that the auxiliary relay HR can become energized for a predetermined period during discharging of this capacitor C1.
  • the capacitor C1 will, after switching of the contact AR2, function as voltage source for the auxiliary relay HR, energizing said relay. As a result thereof the contact HR1 will close activating the motor M of the ventilator causing a gradually increase in air pressure.
  • circuit b Dependent onto the selection of circuit a or circuit b there are now several possibilities. If circuit b is selected and if the ventilator motor M should be maintained in the activated condition through AR1 then within the period into which the capacitor C1 discharges through the auxiliary relay HR, that means within the period into which this auxiliary relay or ventilator relay HR is energized, a holding path should be formed into figure 6 for said ventilator relay HR.
  • circuit b which can include further contacts or other components, forms as a whole a closed path.
  • circuit b is furthermore connected to the output U of the circuit.
  • the power supply voltage is switched through from the terminal 1 to the output U, through which output further parts of the control system can be energized.
  • circuit a comprising eventually further contacts and other components, is in itself a closed path
  • the holding path through circuit a will be a fact as soon as HR1 switches over.
  • the capacitor C1 is only needed to bridge the switching operation of the contact HR1 and it is not necessary to wait for the activation of contact LD2.
  • said ventilator motor M will be switched on and maintained in that position even if the air pressure is very low, however, the output U will not become connected to terminal 1 because LD2 does not switch over, so that further parts of the system to which said ventilator belongs, will not become activated.
  • control relay AR does not function properly, e.g. if the contact AR1 is welded, then also the other contact AR2 will be maintained into the made position, preventing thereby the energizing of the auxiliary relay HR. In that case the ventilator motor M will not start and therefore the air pressure switch LD2 is maintained in the inactive state and no voltage will be supplied to further parts of the system through the output U.
  • figure 7 If the use of relais of the so-called "forced guidance" type is objectionable e.g. because of finacial reasons, then another embodiment illustrated in figure 7 can be used.
  • the components corresponding to the components in figure 6 are indicated by the same reference characters.
  • the control relay AR the auxiliary relay HR, the motor M, a number of resistors R, two capacitors C and a number of diodes D.
  • the start condition circuit comprising the contact HR1 of the auxiliary relay HR and the air pressure switch LD2 is now extended with the contact AR3 of the control relay AR. If all said contacts are in the normal inactive position at the moment the command switch RT switches over, then an energizing path for the control relay AR is set up through said contacts, the rectifying diode D1 and the resistor R1 and R2. In the same way as is already described with reference to figure 1 first of all the capacitor C1 will become charged before the control relay AR will be energized. To prevent the immediate release of the relay AR, caused by switching over of the contact AR3 when said relay is energized, a relatively small capacitor C2 is connected parallel to said relay AR. Said capacitor C2 only bridges the short period into which the contact AR3 switches over. After switching of the contacts of AR a holding path for the control relay AR is formed through AR1 and D6.
  • circuit illustrated in figure 7 is completly identical to that of the circuit illustrated in figure 6 and therefore a detailed discussion of the general functioning of the circuit in figure 7 is superfluous.
  • the diode D6 which is inserted into the holding path for the control relay AR has still another function. If in this circuit or figure 7 one of the contacts AR1 or AR3 for one reason or another becomes stuck in the made position, that this diode D6 takes care that directly after switching of the command switch RT a holding path is formed for the control relay AR. In case AR1 is stuck, then this holding path is built up through AR1 and D6. In case AR3 is stuck then this holding path is built up through AR1, LD2, AR3 and D6. If one of these two contacts therefore is welded or stuck for some reason then the control relay AR will be activated immediately so that the capacitor C1 does not have time enough to charge and therefor the auxiliary relay HR does not become activated.
  • the circuit is therefore brought directly into the locked situation without supplying any voltage to the motor M or through the output U to further parts of the system to be protected. It is remarked that also the eventual welding of the contact AR2 forms a protection in itself. In this case the capacitor C1 cannot be charged at all.
  • the power supply voltage of the circuit illustrated in fig. 8 in many cases the mains voltage, is supplied to the terminal 1 and 2 is rectified by the diode D1.
  • the resulting DC voltage is used to supply the control relay AR and to charge the capacitor C.
  • the diode D2 bridges the second half period into which no current flows and funtions furthermore, just as the diode D3 which is connected parallel to the safety period determining relay VTR to extinguish the self-inductance voltage appearing when the relay AR respectively HR is de-energized.
  • a flame sensing unit of known type is connected to the terminals 1 and 2.
  • Said flame sensing unit comprises a control stage ST, a flame relay VR connected to said control stage and a flame sensing device VW also connected through a the terminals 8 and 9 to said control stage. If a flame is present in the burner then said flame will be sensed by VW with the result that the flame relay VR will be activated by the control stage ST. If no flame is present then VW will not generate a signal and the flame relay will not become activated through the control stage ST.
  • a command switch RT is connected between the terminals 3 and 4. Between the terminals 4 . and 2 the start condition circuit is connected comprising a series circuit of a contact VTR1 of the safety period determining relay VTR and a contact VR1 of the flame relay VR, and furthermore the already mentioned rectifying diode D1, . a pair of current limiting resitors R1 and R2 and the control relay AR with the already mentioned diode D2 parallel therewith.
  • a contact AR1 of the control relay AR is connected parallel to the series circuit of the contacts VTR1 and VR1.
  • the junction between the contact VR1 and the diode D1 is connected to one side of the contact VTR2 as well as to the switch over contact VR2.
  • the other side of VTR2 is through terminal 6 connected to the fuel valve MK of which the other terminal is connected to terminal 5.
  • the switch over contact VR2 is in the normal position inserted into the energizing path for the ignition unit OT, which path runs furthermore through contact VTR3. In the activated position the switch over contact VR2 functions to maintain the fuel valve MK activated after the safety period determining relay VTR is released.
  • This safety period determining relay VTR is connected to terminal 5 and the other side is through the switch over contact AR2 connected to a capacitor C1 to which the other side is connected to terminal 5.
  • the contact AR2 determines a connection from the junction between the resistors R1 and R2 through the capacitor C1 to the terminal 5.
  • R1, R2 and C1 should be selected such that on the one hand the capacitor C1 can become charged before especially contact AR2 switches over and on the other hand the capacitor C1 has to charge such that the safety period determining relay VTR can become energized for a predetermined period during the discharging of this capacitor C1.
  • the capacitor C will, after switching of the contact AR2, funtion as voltage source for the safety period determining relay VTR, energizing said relay. Therefore, the contacts VTR2 and VTR3 will switch to the other position, so that both the fuel valve MK as well as the ignition unit OT will be energized.
  • the ignition OT gets the chance to ignite a flame into the burner. The presence of a flame will be detected by the flame sensing device VW activating the relay VR. The result thereof is that the contact VR2 switches over releasing on the one hand the ignition unit OT and closing on the other hand a holding path for the fuel valve MK.
  • the correct functioning of the safety period determining relay VTR and the flame relay VR is checked each time before the control relay AR is energized.
  • the contacts VTR1 and VR1 in the start condition circuit will in the situation in which the respective contacts are maintained in the made position, prevent energizing of the control relay AR.
  • the energizing path for the fuel valve will not become closed because on the one hand the start condition circuit through VTR1 and VR is not closed and because on the other hand the contact AR1 will not switch over.
  • control relay AR does not function correctly, e.g. if the contact AR1 is welded in the made position, thn also the other contact AR2 will be maintained in this position preventing thereby the energizing of the safety period determining relay VTR. Also energizing of the fuel valve will be prevented in this situation because the contact VTR2 will not switch over in this situation.
  • FIG. 9 Another embodiment illustrated in figure 9 can be used.
  • the components corresponding with the components in figure 8 are indicated with the same reference symbols.
  • the control circuit ST the flame relay VR, the flame sensing device VW, a control relay AR, a safety period determining relay VTR, a thermostat switch RT, a fuel valve MK and an ignition unit OT, and furthermore a number of resistors R and a number of diodes D. It is remarked that the number of contacts for each relay might be different in the various figures.
  • control stage ST, the flame relay VR and the flame sensing device VW are powered in the same way as in figure 8 and also the functioning thereof is identical.
  • the energizing path for the control relay AR comprises besides the thermostat contact RT in this case also contacts of the flame relay VR and the safety period determining relay VTR, in this case the contacts VTR1, VTR2 and VR.
  • the diode D1 rectifies the AC voltage and the resistor R2 determines together with the capacitor C2 a delay period before the relay AR will become energized.
  • the diode D2 has just as the diode D3 the same function as the corresponding diodes D2 and D3 in figure 8. After closing the thermostat switch RT the capacitor C1 will be charged through contacts AR2 and AR3, the rectifying diode D4, the resistor R1 and the contact AR1.
  • the second capacitor C2 connected in parellel to the relay coil AR will be charged through RT, VTR1, VTR2, VR, D1 and R2.
  • the contacts AR1, AR2 and AR3 will switch over finishing thereby the charging of capacitor C1.
  • the charge stored in C1 is therefore dependant onto the values of R1, C1, R2 and C2 as well as the coil resistance of the relay AR.
  • the holding path for the relay AR extends through AR2, D1 and R2 and therefore AR is maintained energized as long as the thermostat contact RT is closed.
  • the capacitor C1 is connected as voltage source to the safety period determining relay VTR1, energizing said relay, so that the contacts VTR1 and VTR2 will switch over.
  • the fuel valve MK is energized through contacts VTR1 and AR3 and the ignition unit OT is energized through contacts AR2, VR, and VTR2. If a flame is ignited within the safety period, then the flame relay will respond thereto, so that VR switches over and the ignition unit is switched off.
  • the fuel value MK is still energized through AR2 and VR, even if the safety period determining relay VTR releases.
  • Figure 10 illustrates a third embodiment of the circuit according to the invention, specially designed for controlling a burner installation. Also this embodiment comprises components of the same type as the components in the already discussed embodiments and these components are also indicated by corresponding reference symbols.
  • the start circuit is formed by the series connection of the contacts VTR1, VR and VTR2 and AR3. Also in this case all contacts of the safety period determining relay VTR and of the flame relay VR are therefore connected into the start condition circuit. If all said contacts are in the normal position at the moment the thermostat contact RT closes, then an energizing path for the control relay AR is formed through said contacts, and furthermore through the rectifying diode D1 and the resistors R1 and R2. In a corresponding way as is described in relation to figure 9 the capacitor C1 will be charged before the control relay AR is energized.
  • the capacitor C2 has in this case a relatively small value and functions only for bridging the short period into which the contact AR3 switches over.
  • the holding path for AR is closed through AR1 and D4.
  • the charged capacitor C1 is connected as the voltage source to the safety period determining relay VTR, energizing said relay resulting into switch over the contacts thereof.
  • the fuel valve MK is activated through AR1, AR3, and VTR2 and the ignition unit OT is activated through AR1, AR2, VR and VTR1. If a flame is ignited then the flame sensing device VW will respond thereto by energizing the flame relay VR with the result that a holding path for the fuel valve is closed through AR1, AR2 and VR. Because VR switches over furthermore the ignition unit OT will be switched off.
  • the control relay AR is maintained energized resulting into a locked situation.
  • the diode D4 is connected to the contacts AR2 and AR3. If in this circuit one of the contacts AR1, AR2 or AR3 becomes for one reason or another welded or is maintained in the made position, then the function of this diode D4 is to take care that after closing of the thermostat contact RT immediately a holding path is formed for the control relay AR. In case AR1 is welded then said holding path runs through AR1 and D4. If AR2 is welded then said holding path runs through VTR1, VR, AR2 and D4. In case AR3 is welded said holding path runs through VTR1, VR, VTR2, AR3 and D4.
  • the advantage thereof is that in all these situations the relay AR becomes immdiately energized leaving no time for the capacitor C1 to charge so that the safety period determining relay VTR will not become energized.
  • the circuit is therefore directly brought into a locked situation without activating the fuel valve of the ignition unit. It is remarked that an eventual welding of AR4 forms a protection in itself. In that case the capacitor C1 will not charge.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Safety Devices In Control Systems (AREA)
  • Relay Circuits (AREA)
  • Control Of Combustion (AREA)

Claims (15)

1. Circuit pour la commande en sécurité d'un système, comprenant un commutateur de commande (RT), un relais de commande (AR), un relais auxiliaire (HR) et un condensateur (C1), ce condensateur, après fermeture du commutateur de commande étant connecté pour être chargé à partir d'une source d'alimentation (1,2) à une tension prédéterminée avant que le relais de commande ne soit alimenté, ce relais de commande étant alimenté par l'intermédiaire d'un trajet d'alimentation contenant au moins un contact (HR1) du relais auxiliaire (HR) et étant maintenu dans l'état alimenté par l'intermédiaire d'un contact du relais de commande, caractérisé en ce que le condensateur (C1) est connecté pour être chargé par l'intermédiaire d'au moins un contact normalement fermé (AR4) du relais de commande (AR) et après alimentation de relais de commande, ledit condensateur (C1) est connecté à un relais auxiliaire (HR) par l'intermédiaire d'au moins un des contacts maintenant commuté (AR4) du relais de commande (AR) et forme pendant une durée prédéterminée la seule source de tension pour le relais auxiliaire (HR), alimentant ce relais auxiliaire.
2. Circuit selon la revendication 1, caractérisé en ce qu'un trajet de maintien pour le relais auxiliaire (HR) vers la source d'alimentation est fermé par l'intermédiaire des contacts commutés (AR3, HR1) du relais de commande (AR) et du relais auxiliaire (HR) (figure 1).
3. Circuit selon la revendication 1, caractérisé en ce qu'il comprend en outre un moyens de commutation (S;M) activé par l'intermédiaire d'un contact du relais auxiliaire (HR) (figures 2,3,4,5,6,7).
4. Circuit selon la revendication 3, caractérisé en ce que le moyen de commutation (S;M) coopère avec un ou plusieurs contacts qui, s'ils sont commutés pendant ladite durée prédéterminée, ferment un trajet de maintien pour le moyen de commutation (figures 2,4,5).
5. Circuit selon la revendication 3, caractérisé en ce que le moyen de commutation (H) coopère avec au moins un contact (LD2) qui peut se former sous l'influence du moyen de commutation à l'intérieur de la durée prédéterminée provoquant ainsi un trajet de maintien pour le relais auxiliaire (HR) par l'intermédiaire du contact du moyen de commutation (M) (figures 6,7).
6. Circuit selon la revendication 3, caractérisé en ce que le contact (HR1) du relais auxiliaire (HR) est connecté dans la trajet de maintien du moyen de commutation (5) (figure 3).
7. Circuit selon l'une des revendications 3 à 6, caractérisé en ce que le moyen de commutation est mis en oeuvre sous forme d'un relais de commutation (S).
8. Circuit selon l'une des revendications précédentes, caractérisé en ce que, initialement, le condensateur (C1) est connecté par l'intermédiaire du contact respectif du relais de commande en parallèle avec ce relais de commande, et le trajet d'alimentation du relais de commande contient de préférence un élément de limitation de courant (R1) pour limiter l'effet transitoire du condensateur (C1).
9. Circuit selon l'une des revendications précédentes, caractérisé en ce que le condensateur (C1) est chargé par l'intermédiaire d'un premier élément de limitation de courant (R1) et par l'intermédiaire du contact associé du relais de commande, et un second condensateur (C2) est connecté en parallèle avec le relais de commande (AR), ce second condensateur étant chargé par l'intermédiaire d'un second élément de limitation de courant (R2) dans le trajet d'alimentation du relais de commande, et les valeurs de résistance et de capacité sont choisies de sorte que la tension prédéterminée sur le premier condensateur (C1) est atteinte au moment où la tension sur le second condensateur (C2) est suffisante pour alimenter le relais de commande (figures 1,2,3,5,7,9,10).
10. Circuit selon l'une quelconque des revendications précédentes 3 à 9, caractérisé en ce que de relais du type à guidage non forcé sont utilisés dans lesquels tous les contacts du relais auxiliaire (HR) et des moyens de commutation (S;M) sont connectés dans le trajet d'alimentation du relais de commande (figures 2,3,5,6,7).
11. Circuit selon les revendications 9 ou 10, caractérisé en ce que tous les contacts du relais de commande (AR) sont contenus dans le trajet de charge du premier condensateur (C1) (figure 9).
12. Circuit selon l'une des revendications précédentes, caractérisé en ce qu'un contact du relais de commande (AR) est connecté au trajet d'alimentation du relais de commande et au moins un des contacts du relais de commande est connecté dans le trajet de maintien du relais de commande, d'où il résulte qu'au moins une diode conductrice (D6) est connectée d'une part au relais de commande et d'autre part aux contacts de relais de commande de sorte que, dans le cas où l'un de ces contacts n'est pas à la position normale au moment où le commutateur de commande se ferme, un trajet d'alimentation pour le relais de commande est immédiatement formé empêchant une charge du condensateur (C1) (figures 1,2,3,7,10).
13. Circuit selon l'une des revendications précédentes, 3 à 12, caractérisé en ce que le moyen de commutation (M) comprend un module de détermination de valeur de seuil (LD2) permettant la commutation des contacts du moyens de commutation dans le cas où un paramètre prédéterminé du système a atteint une valeur prédéterminée (figures 6,7).
14. Circuit selon l'une des revendications précédentes, destiné à la commande d'une installation de brûleur d'où il résulte que le commutateur de commande est mis en oeuvre sous forme d'un commutateur à thermostat dont la fermeture active un relais de commande ou un arbre à came, de sorte que, par l'intermédiaire des contacts commutés du relais de commande, ou respectivement de l'arbre à came, un trajet d'alimentation pour une valve de carburant est fermé, cette installation de brûleur comprenant en outre un relais de flamme qui peut être actionné au moyen d'un dispositif de détection de flamme et est maintenu dans l'état actionné tant qu'une flamme est présente dans l'installation de brûleur, et des moyens pour déterminer une période de sécurité à l'intérieur de laquelle une flamme doit être allumée, caractérisé en ce que la pré- riode de sécurité est déterminée par la premier condensateur (C1) qui, pendant cette période, alimente le relais auxiliaire (HR) mis en oeuvre sous forme d'un relais de détermination de période de sécurité, d'où il résulte que le moyen de commutation est mis en oeuvre sous forme d'un relais de flamme (VR) par l'intermédiaire des contacts duquel la valve de carburant principal (MK) peut être actionnée après une détection de flamme, d'où il résulte en outre que le trajet d'alimentation pour le relais de commande (AR) et/ou l'arbre à came peut seulement être fermé par l'intermédiaire du commutateur à thermostat (RT) dans le cas où au moins les contacts du relais de flamme ainsi que les contacts du relais de détermination de période de sécurité sont à l'état normal (figures 8,9,10).
15. Circuit selon la revendication 14, comprenant des moyens actionnables électriquement pour allumer une flamme, caractérisé en ce que les contacts du relais de flamme (VR) ainsi que du relais de détermination de période de sécurité (HR) sont connectés dans le trajet d'alimentation pour le moyen d'allumage de flamme (DT) (figures 8,9,10).
EP83201384A 1982-09-27 1983-09-27 Circuit de sécurité pour un système Expired EP0109696B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83201384T ATE27732T1 (de) 1982-09-27 1983-09-27 Sicherheitsschaltung fuer ein system.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8203734 1982-09-27
NL8203734A NL8203734A (nl) 1982-09-27 1982-09-27 Inrichting voor het besturen van een brander.

Publications (2)

Publication Number Publication Date
EP0109696A1 EP0109696A1 (fr) 1984-05-30
EP0109696B1 true EP0109696B1 (fr) 1987-06-10

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ID=19840333

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Application Number Title Priority Date Filing Date
EP83201384A Expired EP0109696B1 (fr) 1982-09-27 1983-09-27 Circuit de sécurité pour un système

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EP (1) EP0109696B1 (fr)
AT (1) ATE27732T1 (fr)
DE (1) DE3372011D1 (fr)
NL (1) NL8203734A (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3886894D1 (de) * 1987-10-27 1994-02-17 Vaillant Joh Gmbh & Co Feuerungsautomat.
GB9021214D0 (en) * 1990-09-28 1990-11-14 Black Automatic Controls Limit Control circuit
NL1010618C2 (nl) * 1998-11-20 2000-05-26 Ten Holter Consultancy Systeem voor het parallel voeden en schakelen van elektrische eenheden via verschillende uitgangsschakelingen.

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3999933A (en) * 1974-03-15 1976-12-28 Forney Engineering Company Burner control system
US4035134A (en) 1975-10-14 1977-07-12 Johnson Controls, Inc. Electronic valve seat leak detector
US4116613A (en) * 1977-01-24 1978-09-26 Johnson Controls, Inc. Direct ignition system with interlock protection
FR2414686A1 (fr) 1978-01-11 1979-08-10 Cafap Sa Procede et dispositif de detection automatique d'une flamme
US4194875A (en) * 1978-01-17 1980-03-25 Cam-Stat Incorporated Intermittent pilot ignition system
US4242079A (en) 1978-12-07 1980-12-30 Johnson Controls, Inc. Fuel ignition control system

Also Published As

Publication number Publication date
NL8203734A (nl) 1984-04-16
DE3372011D1 (en) 1987-07-16
ATE27732T1 (de) 1987-06-15
EP0109696A1 (fr) 1984-05-30

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