FR2485165A1 - CONTROL CIRCUIT FOR A HEATING SYSTEM - Google Patents

Abstract

CONTROL CIRCUIT FOR A HEATING SYSTEM COMPRISING AT LEAST ONE FUEL VI DELIVERY MEMBER WHICH IS CIRCUIT-DRIVEN BY A P1 CIRCUIT SWITCH, AN IGNITION DEVICE, AN FW FLAME CONTROLLER AND AN ELECTRONIC SAFETY CLOCK SG OPERATING FOLLOWING TWO SEQUENCES AND ACTUATING A PREPARATION DEVICE IN THE FIRST SEQUENCE AND SWITCHING ON AND OFF THE FUEL DELIVERY MEMBER IN THE SECOND SEQUENCE; THE P1 SWITCHING SWITCH ON THE SG SAFETY CLOCK ENTRY AT THE SAME TIME AS THE FUEL VI SUPPLY MEMBER, AND THE PREPARATION DEVICE 12 IS USED AS THE SWITCHING OFF DEVICE IN THE SECOND SEQUENCE .

Description

2485 165

  Control circuit for a heating installation.

  The invention relates to a control circuit for a heating installation, comprising at least one fuel delivery member which is switched on by a switching switch, an ignition device, a flame controller comprising a relay. of flame and

an electronic security clock, which works

  in two successive sequences in the course of the program and which, in the first sequence activates at the end of the safety period a preparation device which prepares the switching on of the fuel delivery member, and in the second sequence starts with switching on the fuel delivery device,

  and puts this organ re-delivery of fuel-out of circuit

  cooked at the end of the safety period by means of a cut-out device, when the

flame did not respond.

  According to the standard, the safety period is the

  tervalle of maximum admissible time during which the control circuit releases the fuel supply without the emission of a flame. It therefore begins with the delivery of the fuel and when no flame appears ends with the signal to block the supply

of fuel. Security periods are determined.

  They become shorter when the power of the burner

  increases, and in the case of large gas burners no-

  so they are only a few seconds, for

example 2 to 3 seconds. In addition, one should not stray

  ter by too many of these values even for a voltage drop of 15%, a voltage increase of 10% and a temperature variation between 0 and 600 C. Such requirements cannot be satisfied by thermal safety clocks which operate by

example with a bimetallic strip.-

A control circuit of the type described above is known (German patent application submitted for public inspection under NO 19 65 790), in which an electronic security clock is used in which a

capacitor is charged via a resistor

  tance and is discharged via a unijunction transistor and a trip relay when the threshold value of this transistor is reached. In a first sequence, a period of time is determined which can be used as a pre-ignition or pre-ventilation period. Then the trigger relay delivers,

  like a transformer, a commu-

  tation to an electronic switch which switches on a burner relay.

trigger is brought into a prep position

  when the relay in the second sequence receives another pulse, it allows the opening of a switch at the input of the circuit

  control. The clock input is connected by the

  through a first diode, at a point between

the burner relay and the electronic switch are

company and, via a second diode at a point located between the flame relay and a transistor

  switching this relay. It follows that the capacitor asso-

cié is charged as long as the electronic switch and / or the last transistor mentioned are in

blocked state.

  This allows you to check in the first sequence

if the timed electronic system works well. This-

  during, this does not provide any security as to the fact that at the end of the security period, in the second sequence, the fuel delivery member is effectively switched off, when for example the charging track

  passing through the second diode is cut off or when the ar-

  the trip relay should not be activated. Furthermore, the known circuit cannot therefore be used, for very large burners, since the safety periods are much longer

  shorter than the corresponding pre-ventilation periods.

  The invention proposes to provide a control circuit of the type mentioned above in which it is ensured that the fuel delivery member is switched off when no flame has appeared at the end.

of the safety period.

This problem is solved according to the invention. due to the fact that the switch on energizes

  the entry of the safety clock at the same time as the

  fuel delivery hose and the preparation device serves as a cut-off device

in the second sequence.

  In this circuit, we do not only check the correct functioning of the timed system in the first sequence. It is also ensured that when the fuel delivery member receives a voltage the safety clock also receives a voltage. If there is a fault in the safety clock supply conductor, this also prevents the fuel delivery unit from responding. Because one and the same device is used for preparation in the first sequence and for switching off in the second sequence, it is

assured that at the end of the security period in the second

xth sequence is effectively deactivated, since the de-switching function in the first

  sequence has been checked - and in the event of a fault, the organ -

fuel delivery is not switched on. Consequently, a safety clock is obtained having

extremely good reliability.

  Advantageously, the safety clock includes

  carries a relay responding with a certain delay, which

remains energized as long as a voltage is applied to the input.

  Therefore, not only the switch-on time but also the switch-off time

  associated are defined. This facilitates the arrangement of the device.

common preparation positive and. of shutdown compared to a trip relay which simply responds

during a short pulse.

There are many layout possibilities -

of the circuit according to the invention. In one embodiment

  tion preferred, the fuel delivery member can be energized by one. part by means of a first switch which is connected in series with the circuit breaker switch and which is respectively closed at the end of the safety period in the first

2485 165

  sequence and opened in the second sequence by the dispo-

  preparation and deactivation, and, secondly, by means of a second switch which is connected in series with a first flame relay switch in its working position and which is closed by

  the security clock at the end of the security period.

  The first switch already checked in the first se-

  quence returns to the initial state at the end of the safety period in the second sequence. The fact that the operation of the burner can continue is tested using the second switch which plays the role of the first switch insofar as the first switch

- flame relay responded.

  To this end, the first switch can be a two-way switch through which,

  in the repog position, the input of the safety clock

  can be turned on. This offers a possibility

  simple unit to start the first sequence of the safety clock independently of the

switching on.

  In addition, advantageously, the second switching

  tor is a two-way switch through

  diary of which, in the rest position, the ignition device can be energized. Since at the end of the safety period in the second sequence the flame must be present, the ignition can be stopped

  through the second switch.

  According to another characteristic of the invention, the device for preparing and switching off comprises a third switch which is actuated by the safety clock at the end of the safety period,

and an auxiliary relay, equipped with a self-

maintenance, which controls a switch in the supply conductor; of the fuel delivery member, and which is excited in the first sequence and-falls in the second sequence, depending on the actuation

  from the third switch. The use of the auxiliary relay

  liaire makes it easy to use the same behavior

2485-165

  the third switch in the

  first sequence for closing the first switch

tor and in the second sequence for the opening of this switch. In more detail, the auxiliary relay can be energized, on the one hand, by means of the serial connection of the working position of the third switch and of the rest position of a second flame relay switch, and, on the other hand, through the serial connection of the rest position of the third switch and the position of

  work of a self-maintenance switch.

The auxiliary relay can be part of a clock.

ioge of pre-ventilation. On the one hand, this provides a separation

  between the safety period and the pre-ventilation period. On the other hand, for the auxiliary relay we

  may use a necessary component for other reasons.

  what. simplify the constitution of the circuit.

In a preferred embodiment, the switch on is a first programmed switch of a programmed clock which can be switched on,

after the auxiliary fee has responded, through the

middle of the rest position of a third switch

torch relay tor. This programmed clock ensures that between the end of the first sequence and the start of the second sequence there is a defined time interval during which the safety clock can return to

its initial state.

  In addition, the programmed clock may include a second switch programmed at the input of the control circuit which opens after a predetermined delay for switching off due to disturbance. When the third flame relay switch does not respond, shutdown due to disturbance takes place

after said delay interval.

  In addition, the programmed clock may include a third programmed switch which opens before the first programmed switch closes and which is located in the supply conductor of a second fuel delivery member. This second member is therefore closed during the ignition process. If, however, the programmed clock is switched off, by removing the voltage, by actuating the third flame relay switch, the third programmed switch can then connect the second control unit.

fuel.

  Advantageously, the flame controller can be switched to a higher sensitivity before switching on the fuel delivery member and during this time the programmed clock can be switched on via a position. of work

a fourth flame relay switch. If the con-

  flame detector detects foreign light, the clock

  programmed lodge is started and after a certain

time the circuit stops due to disturbance.

According to another characteristic of the invention,

  a service relay is provided which is energized in operation

  the response of the auxiliary relay and includes a self-maintenance switch and a service switch which, in its working position, is in series

  with the switch on. This service relay

  defect ensures that the programmed clock also functions before the instant when the fuel delivery member must be switched on in order to stop the circuit due to disturbance, without the switching on of the start-up comnutator circuit causes fuel to be delivered.

  In particular, the service relay can be re-

  linked to the self-maintenance input of the auxiliary relay via a delay element. The delay ensures that the associated service switch is only switched one

once the first switch connected downstream of the switch

  commissioning person established the link with the

gane of energy delivery.

  In addition, the service switch can be

  titled by a two-way switch which, in its rest position, is connected upstream of the first and fourth flame-relay switches. This simplifies

the constitution of the circuit.

Advantageously, the auto-interlock switch

  of the service relay is connected downstream of the posi-

  service switch and upstream of the

  second and third flame relay. This double function

tion of the self-maintenance switch also simplifies

the constitution of the circuit.

This is also the case when the second and third flame relay switches are joined together in a two-way switch or when the first and fourth flame relay switches are joined together

  into a two-way switch.

  The present invention will be better understood. help

of the following description of a pre-

fairy but not limiting shown in the accompanying drawings

on which ones.

  Figure 1 is a diagram of a control circuit according to the invention; and Figure 2 is a time diagram for the

  normal start-up process of the control circuit.

  The circuit shown in Figure 1 is supplied by a phase of an alternating voltage which is applied

  between terminals 1 and 2. Terminal 1 is connected to the

  input sensor 3, and terminal 2 to a conductor 4 is found

before the potential of the mass. In the lower row, the following elements are shown diagrammatically from left to right: a lamp 5 which lights up in the event of a disturbance; a BM relay which is used for switching on

  of a fan motor and includes a self-contact

bml interview; a pre-ventilation clock TG which includes

an auxiliary relay T responding after a period of pre-

  rage of for example 30 seconds a response input has

  and a self-maintenance input b and which controls a

  tl self-maintenance mutator as well as a first switch

  two-way tor2 associated with the fuel delivery member; a service relay M which has a response input c which is connected, via a delay element 6 in the form

  NTC resistance (with a negative temperature coefficient

tif) at the maintenance input b of the pre-ventilation clock TG,

  and a maintenance input d, which controls a switching

two-way tor ml and auto switch

  maintenance m2; a programmed clock P which uses a.

  thermal delay element, closes a switch for switching on pl after a predetermined time, switches a two-way switch p2 located in the

  input conductor 3 after a predetermined delay time

mined, and opens a third switch p3 shortly before the closing of the switch pl; a security clock SG which comprises a relay S which actuates a two-way switch if, by means of an electronic clock, after a security period which is short and may for example be equal to only 2 seconds, as well as another two-way switch s2 which remains switched as long as a voltage is applied to the safety clock SG; a flame controller FW which comprises a flame relay F to which a voltage can be applied, by

  through a conductor 7, and a signal for aug-

lie sensitivity, - through a conduc-

  tor 8, and which activates a two-way switch fi and another two-way switch f2 when a

flame detector 9 finds light; are coming-

then-an ignition transformer ZT, a first fuel delivery member VI and a second fuel delivery member VII. The circuit is completed by a KT switch controlled as a function of the temperature, for example a boiler thermostat. A switch T is actuated according to the air flow coming from the fan. In normal service, the following operation is obtained which is partially described with reference to the

figure 2.

  When there is a demand for thermal energy and when the KT switch is closed, a voltage is

  applied to the BM relay of the fan motor by the

  switch p3, KT and T. The switch-

  self-maintenance bml closes and the fan motor

running at full speed-

As soon as the air flow from the fan motor -

is detected, the two-way switch T changes

  position so that now the tension is equal

  ment applied to driver 10. This instant is designated

  by ta on the diagram in figure 2. Therefore, the time-

  security box SG receives a voltage via the two-way switch t2. Once the period

  of safety passed, therefore at time tb, the relay S

mutates the two two-way switches si and s2 in

their working position.

  Therefore, the excitation input a of the pre-ventilation clock TG receives a voltage via

  switches ml, fl and s2, so that after a

  predetermined pre-ventilation period, therefore at time tc, the

auxiliary relay T is activated, the auto switch

  maintenance tl closes and the two-way switch t2 switches to the working position. Because of this, the clock

  SG security no longer receives de-voltage. Its two commu-

  slators s and s2 return to the rest position. The first sequence SI of the safety clock is finished o Simultaneously, the switching of t2 has carried out a phase of

  preparation for delivering fuel through

  diary of the driver 11. 'From time tc, the service relay M

  also receives a voltage through the e-

  delay element 6. This therefore corresponds to the ins-

  as long as the ml and m2 switches are actuated. The service relay M is then maintained via

  of the m2 self-maintenance switch.

  Consequently, at the instanttd the programmed clock P receives a voltage via the switches ml, m2 and f2. After a first time interval, namely at te, the switch p3 opens, a short time after, namely at the instant tf, the circuit-switching switch pl closes. This results in the fact that the safety clock SG receives a voltage and that a second sequence SII begins. Simultaneously, the organ

VI fuel delivery system receives a voltage

  sion via switches ml, pl, t2 and conductor 11, and the ignition transformer receives

a voltage via the switch sl.

  Therefore, shortly after, namely at the ins-

  -tg, the flame lights up. The flame relay F changes position and switches the two switches fl and f2 in

  their working position. It follows that the clock pro-

  grammage P no longer receives voltage so that after a certain time, namely at time ti, the switching switch pl opens and the switch p3 closes,

  as a result of which the second com issuing body

bustible VII starts working.

  When the safety period obtained at time tf takes place for the second time, namely up to

at time th, the relay S again switches the commu-

  tators si and s2 in their working position. They-

  follows that the ignition transformer ZT is switched off and that the fuel delivery member VY (and subsequently the second fuel delivery member VII) receives a voltage via the switches ml, m2, f2 and s2. The switching of s2 switches off the auxiliary relay T, which during the last period received a voltage via the switches sl and tl, so that the switch

  t2 returns to the rest position. This has no

  lift for supplying the fuel delivery members, since the conductor 11 receives a voltage by another way. At the same time, the safety clock SG receives a voltage via the

  switch t2 even when the switch pl is open.

  Now the whole installation works and remains in the state it is in until the

KT switch opens.

  Errors regarding the security period

  This is avoided because all the elements necessary for the safety period in the second SII sequence have been checked in the context of the first SI sequence. We therefore obtain a device for preparing and

switch-off 12 which switches on the auxiliary relay

  link T and its switch t2 in the first sequence and deactivate them in the second sequence by actuation of the same type of switch s2 in the first and second sequences. A failure in the second sequence is therefore not conceivable

after not only the operating mode of the system

  timed electronic teme but also the operating mode

  operation of the associated relay S and the switches located

  downstream from the function viewpoint have been contr6-

  les in the first sequence. If there is a fault (cut, short circuit) in the clock supply line

  who is responsible for the security period

  in the second sequence., the fuel is not de-

  delivered, so that no damage can occur

ration.

When no flame appears during the safety period in the second sequence, the switch to

two directions f2 flame relay keeps the posi-

tion shown. At the end of the security period the

  switch t2 goes to the rest position shown.

Therefore, the fuel delivery unit VI is

  switched off, which prevents damage. This-

  during, simultaneously the programmed clock P is again heated by the switches ml, m2 and f2, so that after a predetermined delay, the

  p2 switch changes position, which disengages

cooks the whole installation and connects the signal lamp

sation 5.

If the flame disappears during operation,

  the flame relay switch f2 goes to the posi-

  represented rest, which again puts the or-

off-circuit fuel delivery hoses, and

than a programmed clock voltage P as long as the

  trip trigger p2 responds.

  When a foreign light appears before the

  response from. service relay M (light from walls present

  as long as some afterglow, at an open door, or as a result of a faulty flame detector), the flame controller FW responds, since it receives -12

  a signal to increase its sensitivity through

  re of conductor 8. The flame relay switch fl changes position, so that the programmed clock P receives a voltage via the switches ml and fl until the trigger switch p2 responds. Since foreign light is already detected in general before the relay S of the safety clock has responded, switching on the clock

TG pre-ventilation is avoided.

  LO The circuit shown is designed for installation

  gas burner heater with a fan

air lator which has a power of 350 kW. The safety period is then equal to 2s and the pre-ventilation period is greater than 30s. Such L5 control circuits can, however, also be used for oil burners and heating installations in which the safety period is slightly longer. As fuel delivery devices, it

These are primarily electromagnetic controlled valves.

  tick. One can, however, also use

oil pumps.

% L-:

-. D 0

Claims (18)

CLAIMS. 1. Control circuit for a heating installation, comprising at least one fuel delivery member which is switched on by a switching switch, an ignition device, a flame controller comprising a flame relay and a electronic security clock which operates in two successive sequences in the course of the program and which, in the first sequence operates at the end of the   safety period a preparation device which pre-   protects the circuitry of the delivery device   bustible, and in the second sequence begins with switching on the fuel delivery device and puts this fuel delivery unit out of circulation   cooked at the end of the safety period, by means of a cut-out device, when the   flame did not respond, characterized in that the switching switch on / ih9 energized the input of   the security clock at the same time as the   fuel delivery (VI) and that the preparation device (12) serves as a cut-off device in the second sequence (SII).   2. Circuit according to claim 1, characterized in that the safety clock (SG) comprises a relay (S) responding with a certain delay, which remains excited as long as a voltage is applied to the input.   3. Circuit according to claim 1 or 2, charac- terrified in that the fuel delivery body (VI) can be powered up, on the one hand, median of a first switch (t2) which is connected in series with the switch-of circuit (pl) and which is respectively closed at the end of the safety period in the; first sequence (SI) and -opened in the second sequence (SII) by the preparation and deactivation device (12), and, on the other hand, by   via a second switch - (s1) which is connected Checked in series with a first flame relay switch (f2) in the working position and which is closed by the safety clock (SG) at the end of the safety period. 4. Circuit according to claim 3, characterized in that the first switch (t2) is a switch   two-way through which, in the po-   rest, entry to the security clock (SG) can be powered up.   5. Circuit according to claim 3 or 4, -carac-   terized in that the second switch (SI) is a commu-   two-way guard via which, in the rest position, the ignition device (ZT) can be energized.   6. Circuit according to any one of the claims 1 to 5, characterized in that the preparation device   ration and switch-off (12) includes a third   switch (s2) which is activated by the safety clock   tee (SG) at the end of the safety period, and an auxiliary relay (T), equipped with a self-maintenance device (tl), which controls a switch (t2) in the supply conductor of the fuel delivery device (VI), which is excited in the first sequence (SI) and falls back in the second sequence (SI), depending actuation of the third switch (s2). -   7. Circuit according to claim 6, characterized in that the auxiliary relay (T) is energized, on the one hand, by means of the serial connection of the working position of the third switch (s2) and of the position a second flame relay switch (fli), and, secondly, via the serial connection of the third flame position   switch (s2) and the working position of a self-sustaining guardian (tl). 8. Circuit according to claim 6 or 7, charac-   terized in that the auxiliary relay (T) is part of a pre-ventilation clock (TG).   9. Circuit according to any one of the claims tions 3 to 8, characterized in that the switch on (pl) is a first programmed switch a programmed clock (P) which can be switched on sion, after the auxiliary relay (T) has responded, via the rest position of a third   flame relay switch (f2).   10. Circuit according to claim 9, character-   se in that the programmed clock (P) has a second programmed switch (p2) at the input of the com- request which opens after a predetermined delay for a   cut out due to disturbance.   11. Circuit according to claim 9 or 10, character-   that the programmed clock (P) has three sth programmed switch (p3) which opens before the first programmed switch closes. (pl) and which is in the supply conductor of a second   fuel delivery unit (VII).   12. Circuit according to any one of the claims cations 9 to 11, characterized in that the flame controller (FW) can be switched to a higher sensitivity before switching on the delivery device   fuel (VI) and during this time the clock   grammage (P) can be energized by means of diary of a working position of a fourth commu- flame relay guard (f1).   13. Circuit according to any one of the claims   cations 3 to 12, characterized in that a service relay (M) is provided which is energized as a function of the response of the auxiliary relay (T) and comprises a switch with   self-maintenance (m2) and a service switch (ml) -   which, in its working position, is in series with the   commissioning switch (p.1).   14. The circuit of claim 13, character-   in that the service relay (M) is connected to the self-maintenance input (b) of the auxiliary relay (T) by   via a delay element (6). 15. Circuit according to any one of the claims   tions 12 to 14, characterized in that the   service (ml) consists of a two-way switch   rections which, in its rest position, is connected in -   upstream of the first and fourth relay switches of: flame (fl). - .. = Z485165 16. Circuit according to any one of the claims tions 12 to 15, characterized in that the auto switch   service relay (m2) is connected downstream of the working position of the service switch (ml) and upstream of the second and third relay flame (f2). 17. Circuit according to any one of the claims   tions 9 to 16, characterized in that the second and third   me flame relay switches are brought together in a com- two-way mutator (f2).   18. Circuit according to any one of the claims. tions 12 to 17, characterized in that the first and fourth   flame relay switches are brought together in a commu- two-way guardian (fl) .-