EP1331445B1 - Liquid fuel burner - Google Patents

Abstract

The burner system is designed, so that the regulating unit (40) has a servo motor (42) reversible in its direction of rotation, across which a first adjusting element (50) is operable, for the fuel feed unit (20) and a second adjusting element (60) for the unit (30) for the supply of combustion air. The unit (30) for the supply of combustion air is a fan. The rpm of the fan van be varied across the second adjusting element (60), which is coupled with a fixed specified relationship with the first adjusting element (50).

Description

The invention relates to a burner for fluid fuels according to claim 1.

Household heating systems often use lower-range oil burners. These usually have an oil pump for the fuel supply and arranged in a flow channel damper for metering the combustion air required in the burner. One of the air dam upstream or downstream baffle plate is used to adjust the air flow speed at the burner head. The delivery pressure of the oil pump and the positions of the air damper and baffle plate are so matched to each other after installation of the heating system that takes place after the start-up phase of the burner as low as possible and energy-saving combustion. This once made setting remains unchanged during the entire operating time of the heater, so that in particular during the many startup phases high energy losses occur. Only in the context of regular maintenance, if necessary, a readjustment takes place.

In order to avoid the constant switching on and off of the burner at low heat outputs and to achieve a low-emission combustion both in full load and in partial load ranges, oil burners have been developed in which the fuel flow can be adjusted gradually or continuously to the respective energy requirements. At the same time via an actuator, the air damper and the baffle plate can be actuated such that the supply of air and the speed of the combustion air at the burner head lead to an always optimal combustion.

A burner known for example from DE-C1-43 14 544 has for this purpose an electromotive actuatable control device with a reduction gear and a reversible in its rotational direction geared motor, which is located outside of the burner control, e.g. a conventional heating control operated. The reduction gear carries on at least one transmission shaft formed as a drive shaft transmission elements that convert a rotational movement of the drive shaft into linear actuating movements. One of the transmission elements is frictionally connected to an oil pressure adjusting spindle of the oil pump, while further transmission elements are in communication with the air flap and the baffle plate of the burner. Measuring devices for detecting the process streams and parameters are not required. However, the overall design effort is relatively high, which has an unfavorable effect on the manufacturing costs. In addition, one must adjust all transmission elements relative to each other, so that the air damper and the baffle plate are tracked in response to the movements of the oil pressure adjusting spindle exactly.

DE-C2-196 52 205 also discloses a burner system that can be run in several part load operating points, without requiring an excessive measurement and control effort must be operated. The oil pressure adjusting spindle of an oil pump and the air damper in an air duct are each actuated by a discontinuous drive, such as a stepping motor or a synchronous motor. Its step behavior is used in conjunction with the detected number of delivered control pulses and a separate direction detection as position information. In addition to the two servomotors an additional memory device for recording a map is still required to adjust the fuel-air ratio for each operating point exactly. The expenditure on equipment is relatively high, as is the programming effort, which negatively affects the production costs. A subsequent installation in an existing heating system is not provided and only possible with considerable effort.

A liquid fuel burner system described in EP-B1-0 556 694 uses a speed-controlled blower arranged in an air duct for metering the combustion air supplied to the burner. The air flow rate generated by this is determined by a characteristic measured variable and fed to an electronic control unit. This generates a drive signal for a arranged on a fuel regulator electric actuator motor, which controls the fuel flow rate of a Kalibrierdüse and controls. The latter is between an intermittently promoting Diaphragm pump and a fuel nozzle arranged. In order to set a desired mixing ratio of fuel and combustion air, characteristics of different characteristics must be linked together by the control unit, which can only be achieved by suitable programming. The fuel metering is also superimposed by a lambda control. The signals required for this purpose are supplied by a lambda probe arranged in the exhaust gas outlet. Additional sensors are required to monitor the functionality of the system components. Consequently, the overall regulatory burden is very large. The control system is relatively expensive, which makes the use in smaller home heating systems uneconomical.

The aim of the invention is to overcome these and other disadvantages of the prior art and to provide a burner system for fluid fuels, which is inexpensive to produce by simple means and suitable for use in the lower power range, especially in home heating systems. The fuel flow and the combustion air supply to be optimally adapted to the respective energy requirements with little effort in each operating condition of the burner, without the use of complex measurement and control technology is required. The aim is also easy handling and a reliable long-term operation. Furthermore, you should be able to retrofit existing home heating systems easily and quickly.

Main features of the invention are specified in claim 1. Embodiments are the subject of claims 2 to 21.

In a burner system for home heating systems with a combustion chamber, a fuel feed device, means for supplying combustion air and with a control device for the fuel supply and for the supplied combustion air, the invention provides according to claim 1, that the control device in its direction of rotation reversible servomotor, via which a first actuator for the fuel supply device and a second actuator for the device for supplying combustion air is actuated, wherein the means for supplying combustion air is a fan whose speed is variable via the second actuator, which in a fixed predetermined ratio is coupled to the first actuator.
By this simple as well as inexpensive to be implemented measure the required combustion air is supplied directly to the burner via the blower, ie the blower replaces the required example of oil burners damper, which makes the entire structure clear. When adjusting the fuel quantity delivered by the fuel feed device to the respective energy demand, the speed of the fan and thus the supplied air quantity and its speed are adjusted automatically via the coupling of the actuators, so that almost optimal and low-pollutant combustion of the fuel is achieved in each power stage can. Elaborate measuring equipment or control devices are no longer required. The entire system can be easily retrofitted into existing home heating systems. The assembly and adjustment effort is extremely low.

This also contributes to claim 2, namely, when the second actuator is mechanically coupled to the first actuator. As soon as you actuate the first actuator via the servomotor, the fan speed is automatically set in the predetermined ratio. Further control or regulating measures are not necessary. Claim 3 provides in this case that the second actuator is coupled via a transmission with the first actuator, wherein the transmission according to claim 4 may be a reduction gear. Claim 5 assigns the drive to the second actuator as an alternative.

In the embodiment of claim 6, the second actuator is electrically or electronically coupled to the first actuator, so that the fuel supply and the air supply are controlled synchronously in dependence on the required heating power. By adjusting the amount of fuel delivered by the fuel feed device, the speed of the fan is set directly in order to ensure clean combustion in the respective load ranges. Claim 7 provides in this case that the second actuator is coupled via one of the fuel supply device associated with the first actuator Meßwertaufnehmer.

For the realization of the speed control, it is advantageous if the second actuator according to claim 8 is a signal generator which emits an electronic output signal in response to the adjusting movement and / or the position of the first actuator. This can be forwarded via a simple signal line directly to the blower or in the sense of claim 9 as an underlying to an electronic control circuit. Such components are commercially available as standard, which has a very favorable effect on the production costs. According to claim 10, the second actuator is preferably a potentiometer. In practical testing, it has been found that such a solution is particularly reliable. Alternatively, the Output signal of the signal generator according to claim 11 are generated by at least one Hall sensor, or one uses a magnetic detector according to claim 12.

Advantageously, a reduction gear is integrated in the servo motor of the control device according to claim 13. Moreover, the servomotor according to claim 14 may comprise at least one limit switch, so that the actuators between predetermined settings, such as minimum load and full load, can be moved.

Design advantages result from the measure of claim 15, according to which the fuel feed device and the blower each have their own drive motor. The drive motor of the blower is according to claim 16 preferably a DC motor.

In the embodiment of claim 17, the fuel supply means is an oil pump, wherein the first actuator according to claim 18 is a sensing finger operated by an eccentric, which is in operative connection with an oil pressure valve of the oil pump.

In order to be able to generate mechanical and / or electrical energy in addition to thermal energy when needed, the development of the invention of claim 19 provides that the combustion chamber is assigned an externally heated heat engine. This is according to claim 20 preferably a hot gas engine (Stirling engine), whose heater is arranged in the combustion chamber. According to claim 21, at least one consumer is connected to the heat engine, for example a power generator.

Fig. 1

eine Block-Darstellung eines Brenner-Systems,

Fig. 2

eine schematische Darstellung des Brenner-Systems von Fig. 1,

Fig. 3

eine Draufsicht auf eine Regeleinrichtung,

Fig. 4

eine Druntersicht unter die Regeleinrichtung von Fig. 3 und

Fig. 5

eine Seitenansicht der Regeleinrichtung von Fig. 3.

Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. Show it:

Fig. 1

a block diagram of a burner system,

Fig. 2

1 is a schematic representation of the burner system of FIG. 1,

Fig. 3

a top view of a control device,

Fig. 4

a bottom view under the control device of Fig. 3 and

Fig. 5

a side view of the control device of Fig. 3rd

The generally designated 10 in FIG. 1 burner system is designed for an oil heater. It comprises a combustion chamber 12 and a fuel feed device 20, which takes the liquid fuel from a reservoir 18 and feeds it under predeterminable pressure to a spray gun 14. The fuel feed device 20 is preferably an oil pump that is operated by an electric motor 22. The delivery pressure of the oil pump 20 is - as shown in FIG. 2 - adjustable via an oil pressure control valve 24, whereby the amount of fuel discharged into the combustion chamber 12 is determined. The atomizing burner 14 is located in a housing 15 which is mounted on a side cover plate 13 of the combustion chamber 12. A connecting pipe 16 connects the combustion chamber 12 with an exhaust gas heat exchanger 17, which opens into a (not shown) fireplace.

The combustion air required for the combustion process is sucked through a fan 30 room air independent over the chimney and fed through an air duct 34 to the burner 14, so that in the combustion chamber 12, a combustible oil-air mixture is formed. The blower 30 is driven by its own DC motor 32 whose speed is variable by means of an electronic control circuit 70.

In order to be able to coordinate the amount of air supplied to the combustion chamber 12 or the atomizing burner 14 and the quantity of fuel delivered by the oil pump 20 to achieve the best possible combustion, the burner system 10 is assigned a control device 40. This has a reversible in its direction of rotation servomotor 42 and two actuators 50, 60 which are mechanically coupled to each other via a gear 46.

The servomotor 42 is preferably an electric motor with integrated reduction gear 43, which is controlled by a commercial electronic heating control 19. This is based on the prevailing in a (not visible) boiler temperature control pulses to the servomotor 42 from. Two (not shown in detail) limit switch 44, for example, two cam switches limit the rotation angle range of the motor 42 to a minimum and a maximum position, while with a third switch 44, the motor 42 in a defined intermediate position (start position) can stop. The cam switches 44 are - depending on the power range of the burner - individually adjustable.

The first actuator 50 is - as shown in Fig. 3 - a rotatably mounted on a hollow shaft 51 eccentric disk 52, whose lateral surface is designed as a sliding surface for a sensing finger 54. This is supported against a (not shown) compression spring linearly displaceable in a guide tube 57 which is fixed by means of a screw 58 to the oil pressure control valve 24 of the oil pump 20. It can be seen in Fig. 3 that the eccentric 52 associated end of the sensing finger 54 carries a U-shaped clevis 55 and is supported with a rotatably mounted therein roller bearing 56 on the outer surface of the eccentric disc 52. The opposite (not visible) end of the sensing finger is to control the fuel supply frictionally with the (also not shown) adjusting spindle of the oil pressure control valve 24 in conjunction, so that on the adjusting movement of the eccentric disc 52, the delivery pressure of the oil pump 20 is adjustable. The roller bearing 56 ensures a constantly low friction between the sensing finger 54 and the eccentric 52.

The eccentric disk 52 and the hollow shaft 51 are arranged centrally between two frame plates R, P, which are bolted together by means of spacers D. The frame plate R carries on the outside the servo motor 42, which passes through the hollow shaft 51 with its drive axle 45 and is anchored in this rotatably. The guide tube 57 for the sensing finger 54 protrudes laterally out of the frame R, P, D and can be screwed in this way directly to the oil pump 20 and its valve stub.

The second actuator 60 of the control device 40 is a layer rotational resistance (potentiometer), which is fixed with its housing 62 inside of the frame plate P and with its rotating shaft 67, the frame plate P projects through (see Fig. 4). The terminal lugs 63 of the potentiometer 60 are connected via connecting wires 64 to a socket 65, to which a connecting line 66 can be connected. This connects the potentiometer 60 with the electronic control circuit 70. The latter is connected to the control of the air supply via a further connecting line 72 to the motor 32 of the blower 30. The potentiometer 60 provides - depending on the position of the rotary shaft 67 - an electronic output signal, which is supplied as a base value of the electronic control circuit 70. The latter converts the base value into an output signal which predefines the rotational speed of the fan motor 32.

As shown in FIG. 5, carries the rotary shaft 67 of the potentiometer 60 outside the frame R, P, D, a gear 47, which meshes with a likewise arranged parallel to the frame plate P gear 48. The latter is attached to the free end of the drive shaft 45 of the servomotor 42. Both gears 47, 48 form the Transmission 46, whereby the adjusting movement of the potentiometer 60 is directly coupled to the adjusting movement of the eccentric drive 50, ie an actuating movement of the servomotor 42 driven eccentric disc 52 directly triggers an actuating movement of the rotary shaft 67 of the rotational resistance 60, which in turn causes a change the oil pressure of the oil pump 20 leads directly to a change in the rotational speed of the fan motor 32 and thus to a change in the amount of air supplied. The extent of the adjusting movement of the potentiometer 60 with respect to the adjusting movement of the eccentric disk 52 is determined by the transmission ratio of the gear 46, which in the present embodiment is for example 1: 0.7. The selection of the gear ratio depends on the particular system components used and can be changed at any time by simply replacing the gears 47, 48, if necessary. The workload is extremely low.

Before each start of the burner 14, the oil pressure control valve 24 is brought by the servomotor 42 in the predetermined by the cam switches 44 starting position. After ignition takes over the heating control 19, the control of the servomotor 42, which - depending on the required heating power - between the defined by the further cam switch 44 minimum and maximum position is moved back and forth. If the desired boiler temperature is reached, the burner 14 is not switched off, but moved by means of the servomotor 42 in the minimum position. In this case, the delivery pressure of the oil pump 20 is correspondingly lowered via the first actuator 50. At the same time the air supply is readjusted via the positively coupled second actuator 60, so that in each load range a nearly optimal combustion of the oil-air mixture can take place. The measurement of process parameters or the detection of travel ranges or controlled variables is not required here. Also, in the installation of the burner system 10 no time-consuming adjustment or adjustment work must be performed, i. the handling and assembly of the controller 40 are extremely simple and can be performed by non-professionals. It is also favorable that the control device 40 - as well as the entire burner system 10 - is constructed with simple means extremely compact and space-saving, which simplifies the subsequent installation in existing home heating systems. The control device 40 ensures due to the robust construction even in rough everyday operation for a permanently reliable heating operation.

It can be seen that the burner 14 or the burner system 10 with the aid of the control device 40 forms a modulating burner, which is no longer constantly switched on and off must be, but can go through permanently in each required load range. The respective required energy requirement is determined by the already existing heating control 19 and passed from this to the servo motor 42. This sets the required fuel flow. At the same time, the blower speed is readjusted via the coupling device 46. Energy consumption and pollutant emissions are reduced to a minimum, which has a favorable effect on the efficiency.

In the embodiment of FIG. 2, the burner system 10 is associated with a hot gas engine 80 (Sirling engine) in the form of a positive displacement motor. This has - indicated schematically - a working piston 82 and a displacer 84, which are guided in a (not shown) common cylinder. The heater 86 of the Stirling engine 80 is annular and disposed within the combustion chamber 12, while the regenerator or heat accumulator 87 is located outside. A (not shown) Rhombengetriebe ensures the correct allocation of the discontinuous movements of the working piston 82 and displacer 84, wherein the mechanical work generated is removed via a shaft 88 which carries a suitable flywheel 89.

Connected to the heat engine 80 is a consumer (not shown), such as a power generator, which converts the generated mechanical energy into electrical energy. In this way, the heat energy generated within the combustion chamber 12 can be used to generate electrical energy.

The invention is not limited to one of the above-described embodiments, but can be modified in many ways. Thus, for example, the servomotor 42 can be directly in operative connection with the rotary shaft 67 of the rotary resistance 60, wherein the driving force is transmitted to the eccentric disk 52 via the coupling gear 46. Instead of a DC motor 32, the use of an AC motor, an asynchronous motor or the like. come into consideration, whose speed is adjusted via the potentiometer 60 and a suitable electronic control circuit 70.

As an alternative to mechanical coupling, the second actuator 60 may be electrically or electronically coupled to the first actuator 50, for example, by a transducer associated with the fuel injector 20 in the form a pressure sensor integrated in the oil line or a flow meter. This provides - depending on the oil pressure or flow rate - a corresponding output signal, based on which the output signal of the second actuator 60 is changed. Yet another embodiment employs Hall sensors or magnetic sensors for providing the second actuator 60, which also provide suitable output signals for controlling the motor speed of the blower 30.

In addition to the combustion of oil, any fossil fuels can be used in the burner system 10. It is also conceivable, for example, the use of wood pellets. For this purpose, the fuel supply device 20 and the burner 14 must be modified accordingly. The control device 40, however, is universally applicable, so that the fuel supply and the air supply are always optimally matched.

It can be seen that a burner system 10 for home heating systems has a combustion chamber 12, a fuel feed device 20, a device 30 for supplying combustion air and a controller 40 for the fuel supply and for the supplied combustion air. In order to optimally adapt the fuel throughput and the combustion air supply to the respective energy requirement without expensive measuring and control technology, the control device 40 has a reversible in its direction of rotation servomotor 42, via which a first actuator 50 for the fuel supply device 20 and a second actuator 60 is operable for the means 30 for supplying combustion air, wherein the means 30 for supplying combustion air is a fan whose speed is variable via the second actuator 60, which is coupled in a fixed predetermined ratio with the first actuator 50. The second actuator 60 is preferably a signal generator which emits an electronic output signal depending on the setting movement and / or the position of the first actuator 50, for example a base value for an electronic control circuit 70 which controls the rotational speed of a drive motor 32 of the blower 30.

LIST OF REFERENCE NUMBERS

R, P

frame plate

10

burner system

12

combustion chamber

14

atomizer burner

13

cover

15

casing

16

connecting pipe

17

Exhaust gas heat exchanger

18

Reservoir / tank

19

Heating control

20

oil pump

22

drive motor

24

Oil pressure regulating valve

30

fan

32

drive motor

34

air duct

40

control device

42

servomotor

43

Reduction gear

44

Limit switches

45

drive axle

46

transmission

47, 48

gear

50

first actuator

51

hollow shaft

52

eccentric

54

sensing finger

55

clevis

56

roller bearings

57

guide tube

58

screw head

60

second actuator

62

casing

63

terminal lug

64

connecting wire

65

socket

66

connecting line

67

rotary shaft

70

electronic control circuit

72

connecting line

80

Heat engine

82, 84

cylinder

86

heaters

87

regenerator

88

wave

89

Inertia

Claims (21)

1. Burner system (10) for domestic heating systems with a combustion chamber (12), a fuel feed unit (20), a unit (30) for the supply of combustion air and with a regulating unit (40) for the supply of fuel and for the supplied combustion air, said regulating unit (40) comprising a servo motor (42) reversible in its direction of rotation, allowing to actuate a first adjusting element (50) for the fuel feed unit (20) and a second adjusting element (60) for the unit (30) for the supply of combustion air, and said unit (30) for the supply of combustion air (30) being a fan whose revolutions per minute can be varied via the second adjusting element (60), which is coupled with a fixed specified relationship with the first adjusting element (50).
2. Burner system according to claim 1, characterised in that the second adjusting element (60) is mechanically coupled with the first adjusting element (50).
3. Burner system according to claim 1 or 2, characterised in that the second adjusting element (60) is coupled with the first adjusting element (50) via a gear (46).
4. Burner system according to claim 3, characterised in that the gear (46) is a reduction gear.
5. Burner system according to any one of claims 1 to 4, characterised in that the second adjusting element (60) is drivably connected with the servo motor (42) of the regulating unit (40).
6. Burner system according to claim 1, characterised in that the second adjusting element (60) is electrically or electronically coupled with the first adjusting element (50).
7. Burner system according to claim 6, characterised in that the second adjusting element (60) is coupled with the first adjusting element via a transducer associated with the fuel feed unit (20).
8. Burner system according to any one of claims 1 to 7, characterised in that the second adjusting element (60) is a signal transmitter emitting an electronic output signal depending on the setting movement and/or the position of the first adjusting element (50).
9. Burner system according to any one of claims 1 to 8, characterised in that the second adjusting element (60) provides a base value for an electronic control circuit (70) regulating the rpm of a driving motor (32) of the fan (30).
10. Burner system according to claim 8 or 9, characterised in that the second adjusting element (60) is a potentiometer.
11. Burner system according to claim 8 or 9, characterised in that the output signal of the signal transmitter (60) is produced by at least one Hall sensor.
12. Burner system according to claim 8 or 9, characterised in that the output signal of the signal transmitter (60) is produced by at least one magnetic detector.
13. Burner system according to any one of claims 1 to 12, characterised in that a reduction gear (43) is integrated into the servo motor (42) of the regulating unit (40).
14. Burner system according to any one of claims 1 to 13, characterised in that the servo motor (42) comprises at least one limit switch (44).
15. Burner system according to any one of claims 1 to 14, characterised in that the fuel feed unit (20) and the fan (30) respectively comprise an individual driving motor (22, 32).
16. Burner system according to any one of claims 1 to 15, characterised in that the driving motor (32) of the fan (30) is a direct current motor.
17. Burner system according to any one of claims 1 to 16, characterised in that the fuel feed unit (20) is an oil pump.
18. Burner system according to claim 17, characterised in that the first adjusting element (50) is a tracer finger (54) actuated by an eccentric (52), which is in effective connection with an oil pressure valve (24) of the oil pump (20).
19. Burner system according to any one of claims 1 to 18, characterised in that an externally heated thermal engine (80) is associated with the combustion chamber (12).
20. Burner system according to claim 19, characterised in that the thermal engine (80) is a Stirling engine whose heating unit (86) is disposed in the combustion chamber (12).
21. Burner system according to claim 19 or 20, characterised in that at least one energy consuming element is connected to the thermal engine (80), for example a power generator.

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