EP2023043A1 - Ignition device switch - Google Patents

Abstract

The circuit (20) has a releasing unit (38) initiating ignition process of an ignition unit (22) using a reference voltage connection (PE). A protection unit (58) is provided in addition with an electrical connection for locking the releasing unit depending upon a connection parameter, where electrical connection is produced for the reference voltage connection. The protection unit is formed partially as component of the releasing unit, and exhibits a locking unit for locking the releasing unit.

Description

The invention is based on an igniter circuit according to the preamble of claim 1.

It is from the US 3,142,782 a gas cooker ignition device is known which comprises an ignition unit which is intended to ignite a gas burner by sparking. An ignition of the ignition unit is triggered by a trip unit in the operation of a control element, which is assigned to the corresponding gas burner. The triggering of the ignition process takes place by means of a producible in the operation of the control element electrical contact of the trip unit with a grounded connection.

In particular, the object of the invention is to provide an igniter circuit with improved operating safety characteristics.

The object is achieved by the features of claim 1, while advantageous embodiments and modifications of the invention can be taken from the dependent claims.

The invention relates to an ignition device circuit, in particular for a cooking device, with a trip unit, which is provided for triggering an ignition of an ignition unit by means of a reference voltage terminal.

It is proposed that the igniter circuit has a protective unit which is provided to block the trip unit in response to at least one connection parameter when the electrical connection is made to the reference voltage terminal. It can be achieved by a particularly high level of security. An "electrical connection" is to be understood in this context, in particular an electrically conductive connection, which is made by a solid and / or a liquid. In particular, the consideration of an amount of air as an electrical connection should be excluded. Further, under an "electric Compound "are understood in particular a compound which is made by means of a body having a specific conductivity greater than 10 ^-8 S / m.

The reference voltage connection corresponds in particular to a grounded connection. Advantageously, the reference voltage terminal is formed differently from a mains voltage connection. If the igniter circuit is intended for use in a cooking device, it is advantageous in this context if the reference voltage connection is electrically connected to a component of the cooking device which has a reference voltage, in particular is grounded. Advantageously, this component may be incorporated as part of an adjusting device for adjusting a gas flow, e.g. a gas tap, be formed, to which the Zündvorrichtungsschaltung is assigned. The ignition unit is in particular intended to ignite a gas quantity by means of spark formation, in particular by generating a high voltage. The connection characteristic is in particular an electrical parameter, such as e.g. as a voltage, as a resistor, as a current and so on.

Conveniently, the Zündvorrichtungsschaltung on an electrically conductive contact means for producing an electrical connection to the reference voltage terminal, which is mechanically actuated by means of an operating unit in an operating operation. For this purpose, the contact means is advantageously mechanically coupled to a control element, such as a switch. The operating unit and the contact means connected thereto are advantageously used for the proper triggering of an ignition process of the ignition unit. By the protection unit can be advantageously avoided that a different contact means from the foreign body, by means of which an unintentional electrical connection is made to the reference voltage terminal, actuates unintentional release of the trip unit. This is achieved, in particular, by virtue of the fact that the protection unit takes into account a connection parameter of the electrical connection and that a release or a locking of the deployment unit takes place as a function of the connection parameter. The connection characteristic here serves advantageously as a distinguishing characteristic for distinguishing between an electrical connection to the reference voltage connection, which is produced via the contact means, and an electrical reference voltage connection, which is produced via a foreign body.

A particularly compact and inexpensive construction of the igniter circuit can be achieved if the protective unit is at least partially formed as part of the trip unit. Under a protection unit, which is "at least partially formed as part of the trip unit, should be understood in particular a protection unit having at least one functional component which is part of the trip unit. In this case, the functional component may have a function triggering an ignition process and a function blocking the triggering unit. In this embodiment, a self-locking of the trip unit depending on a connection characteristic can be advantageously achieved.

It is also proposed that the protection unit has a locking unit for locking the trip unit, which specifies a blocking threshold of the connection characteristic. A "blocking threshold" of the connection parameter is to be understood in particular to mean a value of the connection parameter, above or below which a locking of the tripping unit is actuated.

In this context, a particularly secure locking of the trip unit can be achieved if the locking unit has a means that specifies a resistance barrier threshold of the electrical connection. In particular, high reliability can be achieved in the detection of inadvertent establishment of an electrical connection to the reference voltage terminal, when the resistance blocking threshold has a value between 500 ohms and 2000 ohms. Furthermore, a low cost embodiment of the igniter circuit can be achieved when the means has at least one resistor.

In an advantageous embodiment of the invention, it is proposed that the protective unit has a blocking means for blocking the trip unit, which closes a connection circuit comprising the compound produced in the locked state of the trip unit. It can be achieved by a current-carrying connection is provided for electrical connection by a particularly simple monitoring of a connection characteristic of the compound produced. This can be achieved in a particularly simple manner if the blocking means has a switching means which is in a conducting state when the trip unit is in the locked state.

A compact, inexpensive and reliable protection unit can be achieved if the protection unit has a blocking unit for blocking the trip unit, which comprises at least one transistor.

Advantageously, the transistor is switched such that a transition control variable of the transistor is proportional to a connection characteristic. A "transition control variable" should be understood in particular to be a variable which serves to control a transition of the transistor between a blocking state and a conducting state. A particularly simple circuit can be achieved if this transition control variable is a terminal voltage difference of the transistor which is proportional to a connection characteristic. A "terminal voltage difference" of the transistor should in particular be understood to mean a voltage difference between two terminals of the transistor. If the transistor is designed as a bipolar transistor, the terminals of the transistor are the base, the collector and the emitter. Particularly advantageous as a terminal voltage difference in particular the base-emitter voltage of the transistor is proportional to a connection characteristic. Particularly advantageously, a connection characteristic corresponds to a transition control variable of the transistor. In this case, a particularly simple circuit can be achieved if the transistor is connected in such a way that a connection characteristic corresponds to a terminal voltage difference of the transistor.

In this connection, a simple and compact topology of the igniter circuit can be achieved if the blocking unit has a resistor which forms a terminal voltage divider, in particular a base voltage divider for the transistor, when the connection is established in cooperation with the connection. In this case, it can be achieved in a particularly simple manner that a transition of the transistor between its blocking state and its conducting state depends on the resistance of the connection produced. A "terminal voltage divider" for a transistor should in particular be understood to mean a circuit of two resistors in series, a transistor terminal, in particular the base, connecting to this circuit at a connection point which is arranged between the resistors. Here, the manufactured electrical connection with its intrinsic resistance fictitious a resistance of the terminal voltage divider.

It is further proposed that the igniter circuit has at least three transistors, whereby the reliability can be further increased when the trip unit is blocked.

A compact and inexpensive construction of the igniter circuit can be achieved if the igniter circuit has a power supply unit which is provided to supply an ignition unit with a DC voltage. In particular, the igniter circuit may comprise a unit for rectifying a signal related to a mains power connection. The DC voltage may in particular have a value of a mains power supply, such as e.g. 220 V or 230 V.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Fig. 1

ein Gas-Kochfeld in einer Ansicht von oben,

Fig. 2

eine Schaltung einer Zündvorrichtung des Gas-Kochfelds aus Figur 1,

Fig. 3

die Zündvorrichtung in einer perspektivischen Ansicht und

Fig. 4

eine alternative Zündvorrichtung in einer perspektivischen Ansicht.

Show it:

Fig. 1

a gas hob in a top view,

Fig. 2

a circuit of an igniter of the gas hob FIG. 1 .

Fig. 3

the ignition device in a perspective view and

Fig. 4

an alternative ignition device in a perspective view.

FIG. 1 shows a trained as a gas hob cooking device 10 in a view from above. The cooking apparatus 10 has a cooking area in which four burners 12 are arranged, and an operating area with an operating unit 14, which comprises four operating elements 16 designed as handles, which are intended to be actuated by an operator and one each of the burners 12 assigned. The controls 16 are each a part of a gas cock, not shown, which is an adjusting means for adjusting the flow of the corresponding one Burner has flowing gas. This adjusting means may be designed in particular as a rotary body, wherein an adjustment of the flow takes place by means of a rotation of the corresponding control element 16. The controls 16 are also used to light one of the burner 12, which can be done for example by pressing the control element 16. To perform an ignition operation of a burner 12, the cooking device 10 is provided with an ignition device 18, which is shown schematically in the figure by a dashed line. The ignition device 18, in particular a Zündvorrichtungsschaltung 20 of the ignition device 18 is in their structure and operation based on FIG. 2 described in more detail.

In FIG. 2 an internal igniter circuit 20 of the ignition device 18 is shown. The ignitor circuit 20 may be divided into three functional units, each having a different function.

The igniter circuit 20 has an ignition unit 22, which is intended to ignite a gas quantity flowing into the corresponding gas burner 12. This is done by means of a set of electrode pairs 24, which are in contact with the flowing gas in the ignition process and are provided for ignition by sparking. For spark formation by means of the electrode pairs 24, the ignition unit 22 is provided with a high voltage unit 26, which is provided in an ignition process for generating a high voltage between two paired electrodes. This includes a primary transformer winding 28 and a set of secondary transformer windings 30 each forming a closed circuit with a pair of electrodes 24. During an ignition process, the primary transformer winding 28 is fed with an alternating current. For this purpose, the ignition unit 22 has a capacitor C4, which forms a resonant circuit 29 with the primary transformer winding 28.

The ignition unit 22 is further connected to a power supply unit 32 of the igniter circuit 20, from which the ignition unit 22 obtains an electrical energy for an ignition process. This power supply unit 32 is provided to provide a DC voltage for the ignition unit 22. For this purpose, the voltage supply unit 32 has a device for rectifying an alternating current obtained from a mains power supply 36 which is external to the ignition device 18 and which comprises a rectifier 34. In this case, to supply the ignition unit 22 is a signal provided with a DC voltage having the value of a mains voltage, such as 220 V or 230 V.

When an ignition operation of the ignition unit 22 is triggered, an electric current flows through a diode D1 and a resistor R7 in the resonant circuit 29 of the ignition unit 22 formed by the transformer winding 28 and the capacitor C4. In this case, the capacitor C4 charges up to a maximum voltage, which is determined by a Sidac Z connected in the oscillatory circuit 29 (silicon diode for alternating current). Upon reaching this voltage, the capacitor C4 discharges into the primary transformer winding 28 and the Sidac Z. This cycle repeats, generating an AC voltage in the secondary transformer windings 30.

As described above, there is an ignition of the ignition device 18, namely the ignition unit 22, upon actuation of a corresponding operating element 16. For this purpose, the Zündvorrichtungsschaltung 20, a trip unit 38 for triggering an ignition of the ignition unit 22. The trip unit 38 has a first switching means 39, which is designed as npn transistor T3. The switching means 39 is arranged in a circuit formed at least by the oscillating circuit 29 and the power supply unit 32, which serves to supply the ignition unit 22 with electric current. If the switching means 39 is in its conducting state, then the switching means 39 closes this circuit and current can flow to the oscillating circuit 29, whereby an ignition process of the ignition unit 22, as described above, can take place. The switching means 39 is in its blocking state, the circuit is open and the ignition unit 22 is locked. For this purpose, the switching means 39 with the resonant circuit 29 of the ignition unit 22 on the one hand and directly connected to the power supply unit 32. Here, the transistor collector is connected directly to the resonant circuit 29, while the transistor emitter is directly connected to the negative polarized terminal of the rectifier 34. Parallel to the transistor T3, a capacitor C1 is connected.

Now, the structure and operation of the trip unit 38 for activating the transistor T3, that is, for triggering an ignition operation of the ignition unit 22 will be described. The trip unit 38 has a first DC busbar 40, which starts from a grounded reference voltage terminal PE and is connected via a capacitor C2 to a second DC busbar 42. This DC bus 42 is part of the circuit described above for the supply of the ignition unit 22 and connects the negative polarized terminal of the rectifier 34 with the resonant circuit 29. The DC bus 40 is further connected to a further DC bus 44 via a capacitor C3. This DC bus 44 is part of the circuit described above for supplying the ignition unit 22 and connects the positive polarized terminal of the rectifier 34 to the resonant circuit 29. Further, a resistor R6 is arranged in a branch connecting the DC bus 42 to the DC bus 44, which is connected between the transistor T3 and the resonant circuit 29 is connected.

The trip unit 38 has a first branch 46 which connects the first DC bus bar 40 to the second DC bus bar 42. This branch 46 is connected in parallel to the capacitor C2. Starting from the first DC bus 40, a switching means 48 designed as pnp transistor T2 and two resistors R4, R5 are connected in series in the first branch 46 successively. The resistor R4 is connected to the transistor collector of the transistor T2 and the transistor emitter is connected to the DC bus 40. The transistor base of the transistor T3 connects to the branch 46 between the resistors R4, R5. Hereby form the resistors R4, R5 a base voltage divider for the transistor T3, which determines the operating point of the transistor T3. If the transistor T2 is in its conducting state, a current can flow in the branch 46. Here, a base-emitter voltage of the transistor T3 is present, which is selected by the dimensioning of the resistors R4 and R5 such that it is sufficient to enable the transistor T3 in its conducting state. If the transistor T2 is in the blocking state, the transistor T3 is in its blocking state by the corresponding base-emitter voltage.

The trip unit 38 has a second branch 50 which connects the DC busbars 40, 42. In this branch 50, two resistors R3 and R2 are connected in series. The transistor base of the transistor T2 connects to the second branch 50 between the resistors R3 and R2. Hereby form these resistors R3, R2 a base voltage divider for the transistor T2 and set its operating point. Furthermore, a third branch 52 of the trip unit 38 connecting the DC busbars 40, 42 is provided, which has the resistor R2 together with the second branch 50. Between the DC bus 40 and the resistor R2, a switch means 54 formed as a pnp transistor T1 is connected in series with the resistor R2.

The transistor T1 is hereby connected in parallel to the resistor R3. The resistors R2, R3 are connected directly to the transistor collector and the transistor emitter of the transistor T1 is connected directly to the DC bus 40. If the transistor T1 is in a blocking state, a current can flow in the branch 50. This results in a base-emitter voltage of the transistor T2, which is sufficient by the dimensioning of the resistors R3, R2 to enable the transistor T2 in its conducting state. If the transistor T1 is in a conducting state, the transistor T2 is in the off state.

The transistor base of the transistor T1 is directly connected to a terminal S of the ignition device 18. This terminal S is further connected via a resistor R1 to the second DC bus bar 42. With this, the transistor base of the transistor T1 is connected to the second DC bus 42 via the resistor R1. The state of the switching means 54, ie, the transistor T1, depends on a contacting state of the terminal S. Is, as in FIG. 2 As shown, the terminal S is a free terminal, so there is a base-emitter voltage of the transistor T1, through which the transistor T1 is in its conducting state. If the transistor T1 is conductive, then the transistors T2 and T3 are in the blocking state and an ignition process of the ignition unit 22 is prevented. The connection S, the reference voltage connection PE and two further connections L and N represent external connections of the ignition device 18 which are used to establish an electrical connection of the ignition device 18 with further units outside the ignition device 18. In the assembled state of the ignition device 18 in the cooking device 10, the terminals L and N are connected to the mains power supply 36. The reference voltage terminal PE is connected in the mounted state of the cooking device 10 with a grounded, external to the ignition device 18 component 55 of the cooking device 10. This component 55 is preferably a component of the gas tap described above for adjusting a gas flow.

It is now assumed that an operator actuates the ignition element 18 corresponding control element 16 for lighting the corresponding burner 12, for example, by pressing the control element 16 in a lowered position. Here, a contact means 56 is actuated by means of a mechanical coupling unit, not shown, which establishes a direct electrical connection from the terminal S to the reference voltage terminal PE. The contact means 56 is advantageously formed externally to the ignition device 18. Preferably, the contact means 56 in the gas cock described above arranged to adjust a gas flow. When made contact, the terminal S and the transistor base of the transistor T1, the reference voltage of the reference voltage terminal PE. In this case, the transistor T1 is brought into its blocking state due to the resulting base-emitter voltage of the transistor T1, which, as described above, causes a transition of the transistors T2 and T3 in their conductive state and thus activation of the ignition unit 22.

According to the invention, the igniter circuit 20 is provided with a protection unit 58. If an electrical connection is made between the terminal S and the reference voltage terminal PE, the protection unit 58 serves to block the trip unit 38 as a function of a connection characteristic of the electrical connection, in dependence on a resistance characteristic of the electrical connection. Hereby it can be avoided that a foreign body, such as a foreign body, e.g. Water or dirt, electrical connection made to the reference voltage terminal PE triggering an unwanted ignition of the ignition unit 22 actuated. The protection unit 58 has a blocking unit 60, which is provided for blocking the triggering unit 38. In particular, this blocking unit 60 has a blocking means 62, which comprises the switching means 54 formed as transistor T1, and the resistor R1.

It is assumed that an electrical connection of the terminal S to the reference voltage terminal PE is made due to intrusion of a foreign body. The electrical connection, which is shown schematically in the figure by a dashed line, has a resistance, which is referred to as a connection characteristic R _X. When the connection is established, the reference voltage terminal PE is connected to the second DC bus 42 via the connection made and the resistor R1. Here, the electrical connection with the connection characteristic R _X and the resistor R1 form a branch connecting the DC busbars 40, 42. The transformer base of the transformer T1 connects to this branch between the terminal S and the resistor R1. Hereby, when the connection is established, the resistor R1, in cooperation with the electrical connection having the connection characteristic R _X , forms a base voltage divider for the transistor T1. Thus, the transformer T1 has a base-emitter voltage which depends on the connection characteristic R _{X of} the electrical connection.

As is generally known in electronics, the transition of transistor T1 between its blocking state and its conducting state can be controlled by means of a transient control variable. This can be done for example by means of the variation of a terminal voltage difference, which corresponds to a voltage difference between two transistor terminals. In this embodiment, the transistor T1 is formed as a bipolar transistor, wherein a terminal voltage difference corresponds to a voltage difference between two of the terminals base, emitter and collector. In one embodiment, the transistor T1 may be formed as a field-effect transistor, wherein the terminal voltage difference corresponds to a voltage difference between two of the terminals gate, drain and source. The blocking unit 60 with the transistor T1 and in particular the resistor R1 is designed such that a transition control variable of the transistor T1 is linked to a connection characteristic. In the considered embodiment, the base-emitter voltage as the terminal voltage difference is a transition control variable V _BE . If the transition control variable V _BE exceeds a threshold, the transistor T1 is brought into its conducting state. If the transition control variable V _{BE is} below the threshold, the transistor T1 is in its blocking state. Further, in this example, a voltage drop of the established connection between the terminal S and the reference voltage terminal PE represents a connection characteristic V _X , the transient control variable V _{BE being} proportional to the connection characteristic V _X. The transient control variable V _BE varies as a function of the voltage of the transformer base. In the illustrated construction, the voltage of the transformer base corresponds to the voltage of the terminal S, ie in particular the connection characteristic V _X. The voltage of the transformer base is thus proportional to the connection characteristic R _X , wherein the proportionality factor depends on the resistor R1. If the connection parameter R _X increases, the voltage of the transformer base of the transformer T1 and therefore the transition control variable V _{BE increases} . If this transition control variable V _BE exceeds the threshold described above, the transistor T1 is brought into its conducting state and the trip unit 38 is blocked.

The blocking unit 60 with the blocking means 62 having the transistor T1 and the resistor R1 therefore outputs a blocking threshold in the form of a threshold of the connection characteristic V _X , which realizes the transition control variable V _BE necessary for the transition of the transistor T ₁ , and in the form of a resistance blocking threshold of the connection characteristic R _X before, which realizes the necessary for the transition of the transistor T1 threshold of the connection characteristic V _X. As described above, depends Proportionality factor of the connection characteristic V _X to the connection parameter R _X from the resistor R1. Thus, the resistor R1 forms a means 64 which provides a resistance blocking threshold of the electrical connection. If the connection characteristic R _{X of} the electrical connection rises above this resistance blocking threshold, the blocking means 62 is brought into the conducting state, as a result of which the triggering unit 38 is blocked. In the considered embodiment, the blocking unit 60 and in particular the resistor R1 are dimensioned such that the resistance blocking threshold of the connection characteristic R _{x has} a value of 1000 ohms.

The structure of the protection unit 58 is further characterized in that, when the connection is made, the blocking means 62, namely its switching means 54, forms a circuit which comprises the electrical connection between the terminal S and the reference voltage terminal PE. In the conductive state of the switching means 54, i. in the locked state of the trip unit 38, the circuit is closed by the blocking means 62, whereby an electric current can flow through the electrical connection.

Furthermore, the topology of the igniter circuit 20 is characterized in that the protection unit 58 forms part of the trip unit 38. Here, the switching means 54, which is provided as part of the trip unit 38 for releasing an ignition of the ignition unit 22 upon actuation of the control element 16, in addition as blocking means 62 of the protection unit 58, the 38 produced in connection to block the trip unit depending on the connection characteristic R _{X is} provided.

The igniter circuit 20 is further provided with a diode D2, which is connected between the reference voltage terminal PE and the transistor emitter of the transistor T1 and serves to protect the igniter 18 from damage during an inspection of the electrical insulation.

FIG. 3 shows the ignition device 18 in a perspective view. It has a housing 66 in which the in FIG. 2 shown Zündvorrichtungsschaltung 20 is arranged. There are also six output ports 68, with a pair of output ports 68 each for a pair of electrodes 24. In FIG. 4 an alternative embodiment of the ignition device 18 is shown, which is provided with four output openings 68 for two electrode pairs 24.

reference numeral

10

cooking apparatus

12

burner

14

operating unit

16

operating element

18

detonator

20

Zündvorrichtungsschaltung

22

ignition unit

24

electrode pair

26

High-voltage unit

28

transformer winding

29

resonant circuit

30

transformer winding

32

Power supply unit

34

rectifier

36

AC power supply

38

trip unit

39

switching means

40

DC rail

42

DC rail

44

DC rail

46

branch

48

switching means

50

branch

52

branch

54

switching means

55

component

56

contact means

58

protection unit

60

blocking unit

62

blocking means

64

medium

66

casing

68

output port

C

capacitor

D

diode

R

resistance

T

transistor

Z

sidac

PE

Reference voltage terminal

S

connection

V _X

Connection parameter

R _X

Connection parameter

V _BE

Transition control variable

L

connection

N

connection

Claims (14)

Ignition device circuit, in particular for a cooking device, comprising a trip unit (38) provided for triggering an ignition operation of an ignition unit (22) by means of a reference voltage terminal (PE), characterized by a protection unit (58) provided for at a reference voltage terminal (PE) produced electrical connection, the trip unit (38) in response to at least one connection characteristic (V _X , R _X ) to block. Ignition device circuit according to claim 1, characterized in that the protective unit (58) is at least partially formed as part of the tripping unit (38). Ignition device circuit according to claim 1 or 2, characterized in that the protection unit (58) has a locking unit (60) for locking the trip unit (38), which specifies a blocking threshold of a connection characteristic (V _X , R _X ). Igniter circuit according to Claim 3, characterized in that the blocking unit (60) has a means (64) which defines a resistance blocking threshold of the electrical connection. Igniter circuit according to claim 4, characterized in that the resistance barrier threshold has a value between 500 ohms and 2000 ohms. Ignition device circuit according to claim 4 or 5, characterized in that the means (64) comprises at least one resistor (R1). Igniter circuit according to one of the preceding claims, characterized in that the protective unit (58) has a blocking means (62) for blocking the trip unit (38), which in the locked state of the trip unit (38) closes a circuit comprising the connection made. Igniter circuit according to one of the preceding claims, characterized in that the protection unit (58) has a blocking unit (60) for blocking the trip unit (38), which comprises at least one transistor (T1). Ignition device circuit according to claim 8, characterized in that a transition control variable (V _BE ) of the transistor (T1) is proportional to a connection characteristic (V _X , R _X ). Igniter circuit according to claim 9, characterized in that a terminal voltage difference of the transistor (T1) is proportional to a connection characteristic (V _X , R _X ). Igniter circuit according to one of Claims 8 to 10, characterized in that the blocking unit (60) has a resistor (R1) which forms a terminal voltage divider for the transistor (T1) in conjunction with the connection when the connection is established. Igniter circuit according to one of the preceding claims, characterized by at least three transistors (T1, T2, T3). Ignition device circuit according to one of the preceding claims, characterized by a voltage supply unit (32) which is provided for supplying an ignition unit (22) with a DC voltage. Cooking device, in particular gas cooking device, with an igniter circuit according to one of the preceding claims.

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