EP2565540B1 - Device for controlling the fuel volume through a fuel line - Google Patents

Description

The present invention relates to a device for controlling the amount of fuel flowing through a fuel line from a fuel source to a burner.

Such a device with a pressure-controlled double shut-off valve is off DE 20 2005 000 346 U1 known. The double shut-off valve has a first valve and a second valve. The two valves are actuated by a respective pressure-loaded membrane against the force of a closing spring, wherein the voltage applied to the diaphragm control pressure is set in each case via an associated pressure control unit, which is electrically controlled. The two valves are arranged axially aligned with each other.

EP 0 433 595 A1 describes a device for controlling the amount of fuel flowing through a fuel line with a valve housing having an inlet channel, an outlet channel, a first valve channel and a second valve channel. The two valve channels fluidly connect the input channel to the output channel. In the first valve channel, a first valve seat and a third valve seat and in the second valve channel, a second valve seat and a fourth valve seat is present. A first valve tappet carries a first valve member associated with the first valve seat and a second valve member associated with the second valve seat. A second valve lifter carries a third valve member associated with the third valve seat and a valve seat associated with the fourth valve seat fourth valve member. The two valve tappets are each movable by an electrically controllable valve drive. A pressure regulator with a pressurized diaphragm and a control spring mechanically exerts a resultant force on the first valve lifter and moves it, if necessary, to regulate the pressure in the second valve channel. To change the pressure setpoint, either the spring force can be adjusted or changed by the force of a proportional solenoid.

A device for controlling the amount of fuel flowing through a fuel line is also off DE 43 37 703 C1 known. The valve housing of this device has an inlet channel, an outlet channel, a first valve channel and a second valve channel. The two valve channels fluidly connect the input channel to the output channel. In the first valve channel, a first valve seat and in the second valve channel, a second valve seat is present. A valve tappet carries a first valve member associated with the first valve seat and a second valve member associated with the second valve seat. The valve stem is mechanically moved by the pressure difference across a membrane against the force of a closing spring. On one side of the diaphragm, the pressure prevailing in one of the valve channels is applied via a damping nozzle.

A double valve with two valve tappets, each with two valve members is also off DE 101 14 249 A1 known.

A disadvantage of some of the known devices that control lines between the two valves and the respectively associated pressure control element are necessary. As a result, the structure of the housing is complicated. On the other hand, it requires a relatively large force to the two Ventilabsperrglieder to move against the closing force of the closing spring, which are why provided for actuating the valve tappet membrane with a relatively large pressurizing surface.

It can be regarded as an object of the present invention to improve the known device and in particular to improve the ignition of the burner. This object is achieved by a device having the features of claim 1.

According to the invention, the device has a valve housing with an inlet channel and an outlet channel. Within the valve housing, the input channel is connected to the output channel via a first valve channel and a second valve channel. Preferably, the two valve channels are connected in fluidic parallel. In the first valve channel, a first valve seat and in the second valve channel, a second valve seat is provided. A valve lifter movable along its axis carries a first valve member associated with the first valve seat and a second valve member associated with the second valve seat. The distance between the two valve members on the valve stem corresponds to the distance between the two valve seats, so that both valve members can simultaneously rest against the respective valve seat by a closing movement of the valve stem.

The pressure applied to the two valve members via the input channel acts in opposite directions, that is, it exerts a force in the opening direction on the first valve member and a force in the closing direction on the second valve member. Preferably, the area of the second valve member associated with the input channel is greater than the area acted upon by the pressure in the inlet channel of the first valve member when both valve members are in the closed position. Due to the valve stem carrying two valve members, the valve formed thereby can securely shut off both valve channels to the inlet channel without requiring an additional, larger closing force of a closing spring for this purpose. A closing spring provided in a preferred embodiment, which biases the two valve members in the closed position, only has to provide a small closing force. This, in turn, has the advantage that a first valve drive assigned to the first valve tappet requires only a small force in order to hold the two valve members of the first valve tappet in an open position.

The first valve drive is electrically controllable. The electrical energy required to adjust the open position is low because of the small counterforce by the closing spring.

The device also has a pressure sensor which detects the fuel pressure in the valve channel and / or in the output channel and generates an electrical sensor signal depending on the detected pressure. Fluidic control lines in the valve housing, which lead to a valve drive or a valve member, can be omitted thereby. The required for the control or regulation pressure detection via a pressure sensor which generates an electrical signal and transmitted to a control device. Depending on the electrical sensor signal then the valve drive is electrically controlled. In this way, the pressure downstream of the input channel can be regulated.

The valve housing has a comparatively simple structure and can have a basic body which is designed as an extruded profile part. This extruded profile part is sealed fluid-tight after insertion of one or more valve tappet or the pressure sensor by end cover. The device can be produced very easily and inexpensively. Due to the extruded section part a voids formation is avoided in the valve housing, as occurs in cast valve housings. Such voids can affect the stability and tightness of the valve housing and are avoided by the use of an extruded profile part.

The device also includes a second valve lifter having a third valve member and a fourth valve member. The second valve stem is movable by a second, separate electrically controllable valve drive. The third valve member is associated with a third valve seat in the first valve channel and the fourth valve member is associated with a fourth valve seat in the second valve channel. The first valve stem, the first valve member, the second valve member and the associated first and second valve seat and the first valve drive thus form a first valve. The third valve member carrying the third valve member and the fourth valve member, the associated third valve seat, the associated fourth valve seat and the second valve drive form a second valve of the device. The two valves can be controlled separately via the control device. Both valve channels can therefore be shut off by the first valve and / or the second valve. As a result, a high shutdown safety is achieved, in particular when using the device in a gas line. The valves have no pressurized diaphragm for ram actuation. The plunger actuation takes place exclusively via electrically actuatable valve drives, which preferably each have an electromagnet and in each case a magnet armature connected to the plunger.

The pressure sensor is preferably designed so that a voltage is output as the sensor signal, which indicates whether a pressure setpoint predetermined at the pressure sensor is exceeded or undershot. An exact determination of the prevailing pressure based on the sensor signal by the control device is possible, but can be omitted in one embodiment.

In a preferred embodiment, the pressure sensor has a pressure-actuated, movable against the force of a sensor spring membrane, a movement-coupled to the membrane switching contact and at least one switch contact associated mating contact. The switch contact and the mating contact make an electrical connection when they abut each other. The force of the sensor spring determined the pressure setpoint and can be changed manually or electrically operated in an embodiment via an adjusting screw. Preferably, in the direction of movement of the membrane seen on opposite sides of the switching contact each arranged a counter-contact. If the pressure setpoint is undershot, the switching contact moves toward a mating contact, whereas when the pressure setpoint is exceeded, the switching contact is moved in the direction of the other mating contact. With the help of this pressure sensor, a low hysteresis pressure control can be achieved. It is also possible to build an intrinsically safe pressure sensor. The switching distance between the two mating contacts can be chosen so that the switching contact within the allowable tolerance range to the pressure setpoint again and again moved against one of the two mating contacts and the electrical connection is thus repeatedly made for a short time. In such an operation, the reliability of the pressure sensor can be increased.

• Nach der Wärmeanforderung durch den Kessel wird der erste Ventilstößel über den ersten Ventilantrieb abhängig vom Sensorsignal angesteuert, um den Druck gemäß dem vorgegebenen Solldruck einzustellen. Der zweite Ventilstößel wird gleichzeitig ausgehend von der geschlossenen Ventilausgangsstellung über eine vorgegebene Öffnungsbewegung in die vollständig geöffnete Position bewegt. Die Öffnungsbewegung kann beispielsweise eine lineare Bewegung sein. Während dieser Zündphase des Brenners auftretende Druckimpulse bleiben durch die Steuereinrichtung unberücksichtigt. Derartige Druckimpulse während der Zündphase veranlassen keine Änderung der Stellung des ersten Ventilstößels.

The control device is set up to control the operation of the device. According to the invention, the control device for igniting the burner carries out the following steps:

• After the heat request by the boiler, the first valve tappet is actuated via the first valve drive as a function of the sensor signal in order to set the pressure according to the predetermined target pressure. The second valve stem is simultaneously moved starting from the closed valve output position over a predetermined opening movement in the fully open position. The opening movement may be, for example, a linear movement. During this ignition phase of the burner occurring pressure pulses are disregarded by the controller. Such pressure pulses during the ignition phase cause no change in the position of the first valve lifter.

Following the ignition phase, the control device can control the second valve drive such that the second valve tappet with the third and fourth valve member is used as the throttle device for the burner. In this embodiment, throttle devices between the output channel and the burner can be omitted.

• Figur 1 ein Blockschaltbild eines Ausführungsbeispiels einer Vorrichtung zur Beeinflussung der Brennstoffmenge in einer Brennstoffzufuhrleitung,
• Figur 2 ein Blockschaltbild eines bevorzugten Ausführungsbeispiels des Drucksensors bei der Vorrichtung nach Figur 1,
• Figur 3 einen Querschnitt durch das Ventilgehäuse der Vorrichtung nach Figur 1 und
• Figur 4 einen beispielhaften zeitlichen Verlauf, der Position der beiden Ventilstößel, des Drucksignals, sowie des Sensorsignals während und im Anschluss an die Zündphase des Brenners.

Advantageous embodiments of the device according to the invention will become apparent from the dependent claims and the description. In the description of the invention with reference to a preferred embodiment will be explained. The description is limited to essential features of the invention and other conditions. The drawing is to be used as a supplement. Show it:

• FIG. 1 1 is a block diagram of an embodiment of a device for influencing the amount of fuel in a fuel supply line;
• FIG. 2 a block diagram of a preferred embodiment of the pressure sensor in the device according to FIG. 1 .
• FIG. 3 a cross section through the valve housing of the device according to FIG. 1 and
• FIG. 4 an exemplary time course, the position of the two valve lifters, the pressure signal, and the sensor signal during and after the ignition phase of the burner.

In FIG. 1 the block diagram of a device 10 is illustrated, which serves to influence the amount of fuel flowing through a fuel line 11. The fuel line 11 leads from a fuel source 12 to a burner 13. The fuel is preferably gas. In the fuel line 11, a gas valve 14 of the device 10 is used. The gas valve 14 has a valve housing 15 in which an inlet channel 16, an outlet channel 17, a first valve channel 18 and a second valve channel 19 are present. The two valve channels 18, 19 are fluidically connected in parallel to each other. Gas flows into the gas valve 14 via the inlet channel 16, and the gas flows out of the gas valve 14 via the outlet channel 17.

The first valve channel 18 opens at a first valve seat 20 in the inlet channel 16 and at a third valve seat 22 in the outlet channel 17. The second valve channel 19 opens at a second valve seat 21 in the inlet channel 16 and at a fourth valve seat 23 in the outlet channel 17th

At the first valve seat 20 and the second valve seat 21, a first valve is arranged. The first valve 24 has a first valve tappet 25, which is mounted movably in the valve housing 15 in the direction of movement R parallel to its longitudinal axis. The first valve stem 25 carries a first valve member 26 which is associated with the first valve seat 20, and at a distance axially thereto a second valve member 27 which is associated with the second valve seat 21. The two valve members 26, 27 each have an annular sealing element 28, seen in the direction of the longitudinal axis of the valve stem 25 at the respective valve seat 20, 21 associated sides an axially projecting sealing projection 29 and at its axially opposite side by a support ring 30 in Supported in axial direction is.

The valve seats 20, 21, 22, 23 are each formed in the valve housing 15 by an annular shoulder 31 which completely encloses a cylindrical through-hole 32.

The device 10 also has a second valve 40 having a second valve stem 41 on which a third valve member 42 and a fourth valve member 43 are arranged. The structure of the second valve 40 corresponds to the first valve 24, so that reference can be made to the above description.

If the two valves 24, 40 are closed, the respective sealing element 28 rests with its sealing projection 29 against the associated valve seat 20, 21, 22, 23. The first valve stem 25 passes through the respective through hole 32 on the first valve seat 20 and on the second valve seat 21. Likewise, the second valve stem 41 in the closed position of the second valve 40 passes through the through holes 32 on the third valve seat 22 and on the fourth valve seat 23.

The first valve member 26 is arranged in the first valve channel 18. When the first valve 24 is closed, the first valve member 26 rests on the side of the first valve seat 20 assigned to the first valve channel 18. The second valve member 27 is arranged in the input channel 16 and is therefore according to the example therefore with the first valve 24 closed on the input channel 16 associated side of the second valve seat 21 at. Analogously, the third valve member 42 is arranged in the first valve channel 18 and the fourth valve member 43 is arranged in the outlet channel 17. When the second valve 40 is closed, the second valve member 42 abuts the side associated with the first valve channel 18 third valve seat 21 on. In this position, the fourth valve member 43 is located on the output channel 17 associated side of the fourth valve seat 23 at.

In the closed position of the first valve 24, the first surface A1 facing the input channel 16 through the through-hole 32 of the first valve seat 20 is smaller than the second surface A2 of the second valve member 27 facing the input channel 16. When the first valve 24 is closed, the pressure prevailing in the input channel 16 Pressure does not open the first valve 24, since the resulting force exerted on the first valve stem 25 resulting force is directed in the closing direction.

A further hearing of the safety of the gas valve 14 is achieved in that the third surface A3 of the third valve member 42 facing the first valve channel 18 in the closed position of the second valve 40 is larger than the fourth valve 4 facing the second valve channel 19 in the closed position of the second valve 40 Area A4 of the fourth valve member 43. Even if the first valve 24 can not close due to a malfunction and prevails the pressure prevailing at the input port 16 via the first valve port 18 and the second valve port 19 on the second valve 40, the second valve 40 remains in its closed position because the force resulting from the applied pressure is exerted on the second valve lifter 41 in the closing direction.

This in FIG. 3 illustrated valve housing 15 includes a main body 46 which is designed as an extruded profile part. The base body 46 has, in the region of the two valve channels 18, 19, outwardly open recesses 56, which are closed in a fluid-tight manner and, for example, in a gastight manner by means of a cover 47, 48 for forming the valve channels 18, 19 are. The two valve tappets 25, 41 are led out in a gastight manner through the cover 47 associated with the first valve channel 18.

The recesses 56 for forming the two valve channels 18, 19 are open on opposite sides of the main body 46, preferably along the entire length of the valve channels 18, 19 in the longitudinal direction L of the gas valve 14. The through holes 32 of the first valve seat 20 and the third valve seat 22nd are arranged in one of the opening of the recess 56 opposite inner wall 57. The inner wall 57 extends parallel to a longitudinal axis L of the gas valve 14. The same applies analogously to the second valve channel 19, in which the through-holes 32 of the second valve seat 21 and the fourth valve seat 23 are arranged in its inner wall 57, which is preferably parallel to the longitudinal direction L. The mouth 16 a of the input channel 16 and / or the mouth 17 a of the output channel 17 on the base body 46 are arranged coaxially to the longitudinal axis L, for example. A central wall 58 blocks the direct fluidic connection between the input channel 16 and the output channel 17. The longitudinal axis L extends through the central wall 58. The latter is located between the first valve seat 20 and the third valve seat 22 and between the second viewed in the direction of the longitudinal axis L. Valve seat 21 and the fourth valve seat 23rd

Outside the valve housing 15 in each case a magnet armature 50 is connected to the free end of the valve stem 25 and the valve stem 41. Each armature 50 is coaxially enclosed by an electromagnet 51. The armature 50 and the associated solenoid 51 form a first valve drive 52 for the first valve 24 and a second valve drive 53 for the second valve 40. The two valve drives 52, 53 are electrically connected via a Control device 54 is activated. Via the valve drives 52, 53, the valve members 26, 27 and 42, 43 are moved against the closing force of a closing spring 55. In the exemplary embodiment, each valve 24, 40 associated with a closing spring 55, which acts on the respective valve members 26, 27 and 42, 43 with a closing force to the associated valve seat 20, 21 and 22, 23 out. The closing springs 55 may be as shown schematically in FIG FIG. 1 be arranged in the first valve channel 18 and the first valve member 26 and the third valve member 42 act upon. Alternatively, the closing springs 55 could also act on the respective other valve member 27 and 43, respectively, and be arranged in the inlet channel 16 or in the outlet channel 17. Each valve 24, 40 could also have more than one closing spring 55.

The control device 54 is supplied with a sensor signal S of a pressure sensor 60 of the device 10. The device 10 has at least one pressure sensor 60. The pressure sensor 60 detects the pressure p in the first valve channel 18 or in the second valve channel 19 or in the outlet channel 17. For detecting the pressure p in the outlet channel 17, the pressure sensor 60 can also be inserted immediately after the outlet channel 17 into the fuel supply line 11. It is also possible to detect the pressure p at a plurality of the indicated locations and thus to arrange a plurality of pressure sensors 60 as shown in FIG FIG. 1 dashed lines by another pressure sensor 60 is illustrated.

The structure of the pressure sensor 60 is shown in FIG FIG. 2 shown. Via a pressure input 61, the pressure sensor 60 is fluidically connected to the area in that the pressure to be measured p is present. Via the pressure input 61, the pressure p is applied in a pressure chamber 62 of the sensor housing 63. Inside the sensor housing 63, the pressure chamber 62 is at a Position limited by a movable sensor membrane 64. The sensor membrane 64 is acted upon by a sensor spring 65 on the side opposite the pressure chamber 62. The force of the sensor spring 65 presses the sensor membrane 64 against the applied pressure in the pressure chamber 62. The spring force of the sensor spring 65 is variable via an adjusting screw 66. The pressure set point p set can _be set via the force of the sensor spring 65. If the force of the force of the sensor spring 65 acting on the sensor membrane 64 by the pressure p in the pressure chamber 62 is equal, the sensor diaphragm 64 is in the equilibrium of forces. The sensor membrane 64 moves in the corresponding direction with a pressure change.

With the sensor membrane 64, a switching contact 67 is coupled for movement. The switching contact 67 is electrically conductive. On in a measuring voltage UM is created. In the embodiment, the switching contact 67 is pivotally mounted at one end via a pivot bearing 68, while its other end between two mating contacts 69a and 69b is arranged. The two mating contacts 69a, 69b are arranged in the direction of movement of the sensor membrane 64 with a switching distance. The mating contacts 69a, 69b are electrically conductive. At the first mating contact 69a, the first sensor voltage UG and at the second mating contact 69b, the second sensor voltage UK is measured. If the switching contact 67 comes into contact with one of the mating contacts 69a, 69b, the measuring voltage UM is applied to the relevant mating contact 69a, 69b as sensor voltage UG or UK. If the pressure p corresponds to the setpoint pressure, the switching contact 67 in the exemplary embodiment is located between the two mating contacts 69a, 69b. If the pressure in the pressure chamber 62 rises above the desired pressure value p _soll , the switching contact 67 is moved toward the first mating contact 69a. If the pressure p in the pressure chamber 62 drops below the desired pressure value p _soll , the Switching contact 67 to the other, second mating contact 69b.

The two sensor voltages UG, UK are transmitted to the control device 54 as a sensor signal S. The measuring voltage UM for the pressure sensor 60 can be applied via the control device 54, wherein the necessary electrical connection for clarity in the FIGS. 1 and 3 not shown.

The controller 54 may also be transmitted signals B of the burner 13, which describe the operating state of the burner 13 and / or operating requirements of an operator.

In particular, based on FIG. 4 the operation of the device 10 initiated by the control device 54 should be explained in greater detail.

It is assumed that the two valves 24, 40 are in their initial state. Both valves 24, 40 are closed and each valve member 26, 27, 42, 43 is sealingly on the associated valve seat 20, 21, 22, 23 at. The burner 13 is to be turned on and transmits the power-on request to the control device 54 as signal B. This takes place at the first time t0. The control device 54 causes the first valve drive 52 to move the first valve 24 to its maximum open position, so that the opening cross-section Q1 between the first valve member 26 and the first valve seat 20 and the second valve member 27 and the second valve seat 21 assumes the maximum cross-section Q _max ,

The second valve 40 is slowly opened via the second valve drive 53. The movement of the second valve lifter 41 may be linear, for example. The opening cross section Q2 of the second valve 40 thereby increases steadily from the first time t0.

The pressure sensor 60 measures the pressure p in the outlet channel 17. From the first time t0, the pressure p increases. Since this is still significantly lower than the desired pressure value p setpoint _, the switching contact is applied to the second mating contact 69b, so that the measuring voltage UM is present there as the second sensor voltage UK. With increasing pressure p, the switching contact 67 begins again and again briefly to withdraw from the second mating contact 69b, so that as a second sensor voltage UK from a second time t1 a voltage signal is applied, which is equal to zero and equal to the measuring voltage UM alternately. This is in FIG. 4 schematically represented by the hatched area from the second time t1. From a third point in time t2, the pressure p _should already so close to the desired pressure value p, that the switching contact 67 no longer engages with the second counter-contact 69b to the plant. The second sensor voltage UK then remains equal to zero. The switching contact 67 has taken a limbo state between the two mating contacts 69 from the third time t2.

From the third time t2, both the first sensor voltage UK, and the second sensor voltage UG is equal to zero. The pressure sensor 60 indicates to the control device 54 that the pressure p is within the tolerance range around the desired pressure value p _soll . At the third time t2, the opening cross section Q2 at the second valve 40 is further increased. In order to avoid a pressure increase in the outlet channel 17, the opening cross-section Q1 of the first valve 24 is therefore reduced between the third time t2 and a fourth time t3.

The ignition phase of the burner 13 begins at the first time t0. The gas G supplied to the fuel supply line 11 is ignited in a combustion chamber of the burner 13. When the flame is ignited, strong pressure fluctuations occur, which can react on the device 10 via the fuel supply line 11. At a fifth point in time t4, in the exemplary course described here, a pressure pulse I is caused by the burner 13, which is detected via the pressure sensor 60. At this fifth time t4, the first sensor voltage UG rises briefly and assumes the value of the measuring voltage UM. Since the ignition phase of the burner 13 is not yet completed, such pressure pulses I are ignored by the controller 54. If the first sensor voltage UG, which indicates that the pressure p is greater than the desired pressure value p _soll , within a predeterminable time window ΔT assumes an average value which is smaller than a predefined threshold value, then it is concluded that only individual pressure pulses I Burner 13 were initiated. Such changes in the first sensor voltage UG or the sensor signal S remain disregarded during the ignition phase of the burner 13. As a result of such pressure pulses I, no change in the cross-sectional openings Q1 or Q2 of the two valves 24, 40 is caused.

In the embodiment, it is assumed that the ignition phase of the burner 13 is terminated at a sixth time t5. This can be indicated by a burner signal B, for example. For this purpose, for example, a lambda sensor can be used, in particular a sensor which measures the ionization current in the combustion chamber.

If, after the end of the ignition phase, ie from the sixth time t5, the pressure p changes, the opening cross-section Q1 of the first valve 24 is increased or increased reduced to keep the pressure p in the tolerance range by the predetermined pressure setpoint p _soll .

At the here in FIG. 4 illustrated embodiment, the opening cross-section Q2 of the second valve 40 remains constant at the maximum possible opening cross-section Q _max . Alternatively, the controller 54 may control the second valve 40 and use it as an adjustable throttle. An additional throttle in the fuel supply line 11 between the gas valve 14 and the burner 13 can then be omitted. In this embodiment, the pressure p in the first valve channel 18 or in the second valve channel 19 is preferably regulated via the first valve 24.

The invention relates to a device 10 with a gas valve 14 for influencing the flow rate of a gas G through a fuel supply line 11 to a burner 13. The gas valve 14 has a first valve 24 and a second valve 40. Both valves 24, 40 are designed as double-seat valves, each with two valve members 26, 27 and 42, 43. Each valve 24, 40 has an electromagnetic valve drive 52, 53. Via a control device 54, the two valve actuators 52, 53 are independently controllable. A pressure sensor 60 detects a pressure p downstream of the first valve 24. With the aid of the first valve 24, the control device 54 performs pressure regulation at the pressure measuring point of the pressure sensor 60. The second valve 40 connected downstream of the first valve 24 in the direction of flow of the gas G can be used as a throttle. Depending on the required burner output, the volume flow or the mass flow of the gas G through the fuel supply line 11 via the second valve 40 can be adjusted by controlling the valve drive 53 by the control device 54.

LIST OF REFERENCE NUMBERS

10

contraption

11

fuel line

12

fuel source

13

burner

14

gas valve

15

valve housing

16

input channel

17

output channel

18

first valve channel

19

second valve channel

20

first valve seat

21

second valve seat

22

third valve seat

23

fourth valve seat

24

first valve

25

first valve lifter

26

first valve member

27

second valve member

28

sealing element

29

sealing projection

30

support ring

31

annular shoulder

32

Through Hole

40

second valve

41

second valve lifter

42

third valve member

43

fourth valve member

46

body

47

cover

48

cover

50

armature

51

electromagnet

52

first valve drive

53

second valve drive

54

control device

55

closing spring

56

recess

57

inner wall

58

central wall

60

pressure sensor

61

pressure input

62

pressure chamber

63

sensor housing

64

sensor diaphragm

65

sensor spring

66

adjustment

67

switching contact

68

pivot bearing

69a

first counter contact

69b

second mating contact

A1

first surface

A2

second surface

A3

third area

A4

fourth area

B

Signal of the burner

I

pressure pulse

L

longitudinal axis

p

print

P _should

Index pressure value

Q1

Opening cross section of the first valve

Q2

Opening cross section of the second valve

Q _max

maximum opening cross-section

R

movement direction

S

sensor signal

t

Time

t1 ... t5

time

.DELTA.T

Time window

UG

first sensor voltage

UK

second sensor voltage

AROUND

measuring voltage

Claims (11)

1. Device (10) for controlling the amount of fuel (G) flowing through a fuel line (11), with a valve chamber (15), which has an inlet channel (16), an outlet channel (17), a first valve throat (18) and a second valve throat (19), wherein the two valve throats (18, 19) fluidically connect the inlet channel (16) with the outlet channel (17),
   with a first valve seat (20) and a third valve seat (22) in the first valve channel (18) and with a second valve seat (21) and a fourth valve seat (23) in the second valve channel (19),
   with a valve plunger (25), which bears a first valve member (26) associated with the first valve seat (20) and a second valve member (27) associated with the second valve seat (21),
   with a second valve plunger (41), which bears a third valve member (42) associated with the third valve seat (22) and a fourth valve member (43) associated with the fourth valve seat (23) and which is movable by means of an electrically operable second valve drive (53),
   with an electrically operable first valve drive (52) for moving the valve plunger (25), with a pressure sensor (60), which generates an electrical sensor signal (S) depending on the pressure (p) in a valve channel (18, 19) and/or in the outlet channel (17),
   with a control device (54), which actuates the first valve drive (52) depending on the sensor signal (S), characterised in that the control device (54) is arranged to control the amount of fuel (G) through the fuel line (11) to a burner (13) during its ignition phase with the following steps:

   - actuating the first valve drive (52) operating the first valve plunger (25) depending on the sensor signal (S) for adjusting the pressure (p) on the pressure sensor (60) in accordance with a predetermined desired pressure (p_des), wherein during the ignition phase of the burner (13) pressure pulses (I) arising in the fuel line (11) are detected and cause no change to the operation of the first valve drive (52),

   - actuating the second valve drive (53) operating the second valve plunger (41) for moving the third valve member (42) and the fourth valve member (43) out of a starting position fully closing the opening cross-section (Q2) at the associated valve seats (22, 23) into an end position adjusting the maximum possible opening cross-section (Q_max).
2. Device according to claim 1 characterised in that the pressure sensor (60) only indicates whether the pressure (p) is higher or lower than the predetermined desired pressure (p_des).
3. Device according to claim 1, characterised in that the pressure sensor (60) has a sensor membrane (64), which is subjected to pressure and is movable against the force of a sensor spring (65), a switching contact (67) motion-coupled to the sensor membrane (64) and at least one counter contact (69a, 69b) associated with the switching contact (67), wherein the switching contact (67) and the counter contact (69a, 69b) create an electrical connection when the switching contact (67) rests on the counter contact (69a, 69b).
4. Device according to claim 3, characterised in that the desired pressure (p_des) can be adjusted or predetermined by the force acting on the sensor membrane (64) and predetermined by the sensor spring (65).
5. Device according to claim 3, characterised in that the pressure sensor (60) has two counter contacts (69a, 69b), which are arranged on opposite sides of the switching contact (67) in the direction of movement of the sensor membrane (64).
6. Device according to claim 3, characterised in that a measurement voltage (UM) is applied to the switching contact (67) and the control device (54) evaluates the sensor voltage (UG, UK) present at the counter contact (69a, 69b) to assess the pressure (p) present at the sensor membrane (64).
7. Device according to claim 1, characterised in that the first valve member (26) and the second valve member (27) are subjected to a closing force of a closing spring (55), wherein the closing force is directed towards the respective valve seat (20, 21).
8. Device according to claim 1, characterised in that the third valve member (42) and the fourth valve member (43) are subjected to a closing force of a closing spring (55), wherein the closing force is directed towards the respective valve seat (22, 23).
9. Device according to claim 1, characterised in that the control device (54) is arranged to operate the second valve drive (53) in order to use the second valve plunger (41) with the third valve member (42) and the fourth valve member (43) and the associated valve seats (22, 23) as throttle device.
10. Device according to claim 1, characterised in that the two valve channels (18, 19) are connected fluidically in parallel.
11. Device according to claim 1, characterised in that the valve chamber (14) has an extruded profile part (16), in which the valve seats (20, 21, 22, 23) are arranged.

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