Electrode assembly for a burner system of a heating device, burner system, and heating device

Abstract

1. Electrode assembly for a burner system, burner system, and heating device having such a burner system 2.1 An electrode assembly for a burner system of a heating device is known which has an electrode support oriented on a vertical plane relative to the burner system in an operationally-ready mounted starting position; a ground electrode which is secured to the electrode support; and an ignition electrode having an ignition electrode wire and an ignition electrode ceramic which holds the ignition electrode wire and is secured to the electrode support. 2.2 According to the invention, the ground electrode is oriented at least largely parallel to the vertical plane of the electrode support, the ignition electrode ceramic holding the ignition electrode wire is secured to the electrode support at least largely orthogonally to the vertical plane of the electrode support, and the ignition electrode wire protrudes from the ignition electrode ceramic and extends to the electrode tip thereof while curving towards the ground electrode in such a way that the electrode tip moves in a circular path relative to the ground electrode under the effect of gravity in the event of an aging-related deformation of the ignition electrode wire such that the ignition distance to the ground electrode remains constant and / or decreases. 2.3 The invention also relates to a use for heating devices of caravaning vehicles.

Description

[0001] Electrode arrangement for a burner system of a heating appliance, as well as burner system and heating appliance

[0002] The invention relates to an electrode arrangement for a burner system of a heating appliance, comprising an electrode carrier which, in its ready-to-use state, is aligned in a vertical plane relative to the burner system, a ground electrode which is attached to the electrode carrier, and an ignition electrode which has an ignition electrode wire and an ignition electrode ceramic which holds the ignition electrode wire and is attached to the electrode carrier. The invention further relates to a burner system for a heating appliance with such an electrode arrangement and to a heating appliance for a caravanning vehicle with such a burner system.

[0003] From DE 196 16 617 A1, a pilot burner with a gas injector is known, which has an electrode arrangement comprising an ignition electrode, a ground electrode, and an ionization electrode. The ground electrode is U-shaped and curved symmetrically around an outlet of the gas injector. The orientation of the ground electrode is symmetrical to the gas outlet of the gas injector to prevent one-sided deformation of the ground electrode.

[0004] DE 20 2015 104 356 U1 discloses a burner having an ionization electrode whose electrode tip projects into a flame area of ​​the combustion chamber. During burner operation, the ionization electrode generates an ionization current, which is detected and processed by control electronics to monitor the presence of the flame. Ionization electrodes can deform due to the high temperatures in the flame area. To counteract such deformation, the known burner uses a double-wire ionization electrode, which is significantly stiffer than previous ionization electrodes.

[0005] From DE 102010004 345 A1, an electrode arrangement is known in which deformation is counteracted by providing an electrode body projecting into the flame during operation of a heating burner with an electrode body extension made of a material with a scale resistance of < 1000 °C. The electrode body itself has a scale resistance of > 1200 °C. The electrode serves as a monitoring electrode for the heating burner. From DE 10 2017 119 077 A1, a vehicle heater is known with a heater housing that includes a burner chamber assembly. The burner chamber assembly is supplied with combustion air and fuel. A heat exchanger section is also provided, which includes a heat exchanger housing that is open to airflow.

[0006] The object of the invention is to create an electrode arrangement, a burner system and a heating device of the type mentioned above, which enable reliable operation using simple means.

[0007] The problem underlying the invention is solved for the electrode arrangement by aligning the ground electrode at least largely parallel to the vertical plane of the electrode carrier, by attaching the ignition electrode ceramic holding the ignition electrode wire to the electrode carrier at least largely orthogonal to the vertical plane of the electrode carrier, and by having the ignition electrode wire protrude from the ignition electrode ceramic on an end face facing away from the electrode carrier and curve towards the ground electrode at its electrode tip, such that the electrode tip moves along a path relative to the ground electrode in the event of age-related deformation of the ignition electrode wire, depending on gravity, so that the ignition distance to the ground electrode remains constant and / or decreases. The ground electrode is thus aligned at least largely in a plane parallel to the vertical plane of the electrode carrier.

[0008] The geometric arrangement of the electrode tip of the ignition electrode relative to the ground electrode according to the invention enables, over a certain aging process during operation of the electrode arrangement within a burner system, at least a largely constant ignition gap and / or a reduction of the ignition gap with a correspondingly lower ignition energy. This enables reliable operation of the electrode arrangement in a burner system using simple means, even if the electrode arrangement is permanently exposed to flames. If, during operation of a burner system, the ignition gap between the electrode tip of the ignition electrode and a sheath of the ground electrode becomes too small or drops to zero, ignition is no longer possible and the burner system is in a safe state.

[0009] According to the invention, the electrode carrier is vertically oriented and thus parallel to a burner surface of the burner system as soon as the electrode arrangement is mounted in its operationally ready initial position within the burner system. Because the ignition electrode wire projects approximately horizontally in this operationally ready initial position, its center of gravity lies horizontally at a distance from the electrode carrier. Due to gravity, the ignition electrode wire can gradually deform during operation of the burner system. The geometric orientation of the ignition electrode wire and the ground electrode is designed such that the electrode tip of the ignition electrode wire follows a curved or circular path relative to its attachment point on the electrode carrier, depending on the age-related deformation of the ignition electrode wire.In its fully assembled position, the ignition electrode wire extends approximately horizontally from the ceramic ignition electrode and curves towards the ground electrode. The ignition electrode wire is made of a scale-resistant material, preferably with a temperature resistance of at least 1200 °C.

[0010] The electrode arrangement according to the invention thus advantageously avoids an aging-related increase in the distance between the electrode tip and the sheath of the ground electrode, and consequently an increase in the ignition energy required for ignition. Since the provided ignition energy is limited by the circuit design, an increase in ignition energy beyond its circuit-related limit, which would result from an increasing electrode gap, would lead to uncontrolled and unreliable ignition processes, potentially causing misfires and / or deflagrations.

[0011] The term "ready-to-operate" refers to the state after the electrode assembly has been completed and installed in the burner system, but before the burner has been operated. Thus, the ready-to-operate initial state defines a new condition for the electrode assembly and the burner system. A mounting area for the ground electrode and a mounting point for the ignition electrode ceramic are spaced apart along the electrode carrier. The curvature and length of the ignition electrode wire are dimensioned such that the electrode tip terminates, at least largely, in the plane in which the ground electrode is aligned. Therefore, the ignition gap is also geometrically defined within this plane of the ground electrode.

[0012] The electrode arrangement according to the invention is used for burner systems of heating appliances, preferably for burner systems of heating appliances used in caravanning vehicles. Liquefied gases such as propane or butane can be used as fuels. Such heating appliances can be combined with another functional system, in particular a water storage system, within a caravanning vehicle. A caravanning vehicle is both a motor-driven and a towed land vehicle. Similarly, such a heating appliance can also be used for watercraft and aircraft.

[0013] In this embodiment of the invention, the electrode tip of the ignition electrode wire is positioned at least largely in the plane of the ground electrode. In its ready-to-use, assembled position, the ground electrode is aligned at least largely parallel to the vertical plane of the electrode carrier. The ignition electrode wire terminates with its electrode tip at least largely in this plane.

[0014] In a further embodiment of the invention, in the ready-to-use, assembled initial position, the sheath of the ground electrode and the electrode tip of the ignition electrode wire have an ignition gap of between 3.5 and 4.5 mm, preferably 4 mm, relative to each other. During a corresponding ignition process, an ignition spark jumps between the electrode tip of the ignition electrode wire and the sheath of the ground electrode, but not across the electrode tip of the ground electrode itself. The described ignition gap range is particularly advantageous for reliable ignition without wasting ignition energy.

[0015] In a further embodiment of the invention, the ground electrode is referenced to the fully assembled initial position and, viewed from above, is inclined to a vertical plane. The ignition electrode wire projects beyond the ground electrode in an arc, intersecting the ground electrode when viewed from above. The ignition electrode wire curves over the ground electrode from this perspective, with the electrode tip of the ignition electrode wire ending laterally next to the surface of the ground electrode at the ignition distance.

[0016] In a further embodiment of the invention, the ground electrode and the ignition electrode wire - in relation to the ready-to-use initial position - are aligned relative to each other at an angle between 43° and 58°, with reference to the top view of the vertical plane.

[0017] In a further embodiment of the invention, the ground electrode and the ignition electrode wire – in the fully assembled initial position – are aligned at an angle of 53° relative to each other, as viewed from above on the vertical plane. The ignition electrode wire is aligned in a plane inclined at 40° to the vertical.

[0018] In a further embodiment of the invention, the ground electrode is designed as a straight steel rod and is welded or brazed to a surface of the electrode holder in a horizontal position. This places the ground electrode almost in the vertical plane of the electrode holder, as it rests on the surface of the electrode holder and is bonded there, in this case by welding or brazing. The electrode holder, like the ground electrode, is electrically conductive. The same applies to corresponding welds or brazed seams.

[0019] In a further embodiment of the invention, the ignition electrode is coupled to an ammeter that measures the ionization current generated at the ignition electrode during burner operation. This ionization current serves to monitor the burner system. The generated ionization current is evaluated by an electronic control unit and processed for controlling the heating appliance. In addition to its ignition function, the ignition electrode thus also enables a monitoring function. Due to the dual function of the ignition electrode, a separate ionization electrode is not required.

[0020] For the burner system, the problem underlying the invention is solved by the features of claim 9. For the heater, the problem underlying the invention is solved by the features of claim 10. The burner system comprises an electrode arrangement as described above. The heater is intended for a towed or motor-driven caravanning vehicle and has a burner system with the electrode arrangement as described above.

[0021] Further advantages and features of the invention will become apparent from the claims and from the following description of a preferred embodiment of the invention, which is illustrated with reference to the drawings.

[0022] Fig. 1 shows an embodiment of a heating device according to the invention in a longitudinal section view,

[0023] Fig. 2 shows an enlarged embodiment of a burner system according to the invention for the heating appliance according to Fig. 1 in a partially cutaway side view.

[0024] Fig. 3 shows the burner system according to Fig. 2 in a front view,

[0025] Fig. 4 shows the burner system according to Figs. 2 and 3 in a side view in the direction of the arrows.

[0026] IV-IV in Fig. 3 with a subsequent flame tube of a heating device according to Fig. 1 in a sectional view,

[0027] Fig. 5 shows the arrangement according to Fig. 4, but in the opposite side view in the direction of arrows VV in Fig. 3, also with the flame tube in a cutaway view; Fig. 6 shows the burner system according to Figs. 2 to 5 in a cutaway view along the section line Vl-Vl in Fig. 3 and

[0028] Fig. 7 shows a top view of an embodiment of an electrode arrangement according to the invention for a burner system according to Figs. 2 to 6 of a heating device according to Fig. 1.

[0029] A heater 1 according to Fig. 1 is intended for use in a caravanning vehicle. The heater 1 has a burner system 2 with an electrode arrangement 3. The burner system 2 connects – shown on the right in the drawing according to Fig. 1 – longitudinally to a burner chamber 4, to which gas is supplied via a gas valve 7 and combustion air via an inlet not shown in detail. A combustion air blower 6 is associated with the burner chamber 4, which is driven by a combustion air motor 5. On the right side of the heater in Fig. 1, a recirculating air blower 12 is also provided, which is driven by a recirculating air motor 11.

[0030] Extending longitudinally along the heating unit 1 to the left relative to the burner system 2 is a flame tube 8, which is integrated into a heat exchanger 10. Exhaust gases can escape into the environment via an exhaust gas outlet 9.

[0031] As can be seen from Figs. 1 to 7, the burner system in its ready-to-use initial position is aligned within the heating device 1 in a vertical plane that runs orthogonally to a central longitudinal axis of the heating device 1.

[0032] A dimensionally stable burner housing ring B is rigidly connected in the vertical plane to a housing of the heating device 1 (see especially Figs. 2 to 6). The burner system 2 carries an electrode assembly 3, which is rigidly connected to the burner housing ring B. The electrode assembly 3 has an electrode carrier 13, which is made of an electrically conductive, dimensionally stable material and is designed in a plate-like form. Advantageously, the electrode carrier 13 is made of steel. The electrode carrier 13 is aligned in a vertical plane V, which is parallel to the vertical plane in which the burner housing ring B is positioned. As can be seen from Fig. 3, the electrode carrier 13 is positioned on a ring section of the burner system 2 in its ready-to-use initial position and extends in a circular arc over approximately one quarter of the circumference of this ring.

[0033] A rod-shaped ground electrode 14 is attached to a surface of the electrode carrier 13 facing the flame tube s. The ground electrode 14 is aligned in a vertical plane V2 that runs parallel to the vertical plane \ / ^ of the electrode carrier 13. The ground electrode 14 is designed as a cylindrical steel rod and is welded to the surface of the electrode carrier 13, as can be seen from the weld seam in Fig. 3.

[0034] As can be seen in Fig. 3 and Fig. 7, the ground electrode 14 is aligned in its vertical plane relative to a vertical V3 at an acute angle, with this angle to the vertical V3 being 13° in the illustrated embodiment.

[0035] Also attached to the electrode carrier 13 is an ignition electrode 15, 17, 18, which comprises an ignition electrode ceramic 15 and an ignition electrode wire 17 with an electrode tip 18. The ignition electrode ceramic 15 is a hollow cylindrical component that coaxially surrounds and insulates the ignition electrode wire 17.

[0036] As can be seen in Figures 4 to 6, the ignition electrode ceramic 15 extends through the electrode carrier 13 and projects approximately half its length into the burner chamber 4. Accordingly, the ignition electrode wire 17, which is encased by the ignition electrode ceramic 15, also projects parallel to the central longitudinal axis of the heating device 1 into the burner chamber 4 and is connected to a current measuring system 16. This system detects ionization currents generated by the ignition electrodes 15, 17, 18 and transmits them (not shown) to a control unit, which in turn evaluates corresponding ionization currents to control the heating device 1. The ignition electrode ceramic 15 is fixed in the electrode carrier 13.

[0037] As can be clearly seen in Figures 2 to 7, the ignition electrode wire 17 projects horizontally on the side facing the flame tube 8 over an end face of the ignition electrode ceramic 15, parallel to the central longitudinal axis of the heating device 1, and thus in the operationally assembled initial position shown in Figure 1. It then transitions to an arc-shaped curve towards its electrode tip 18, which curves downwards back into the vertical plane V2 of the ground electrode 14. As can be seen in Figures 5 and 6, the electrode tip 18 of the ignition electrode wire 17 is positioned in the vertical plane V2 of the ground electrode 14 in the operationally assembled initial position, with the electrode tip 18 having an ignition gap of 4 mm to a cylindrical surface of the ground electrode 14 in the operationally assembled initial position.

[0038] Figures 3 and 7 clearly show that, with the electrode carrier 13 mounted on the burner system 2, the plane of curvature of the ignition electrode wire 17 is oriented at an angle α to the longitudinal extent of the ground electrode 14. In the illustrated embodiment, the angle α is 53°. Furthermore, the plane of curvature of the ignition electrode wire 17 is inclined relative to the vertical V3 at an angle β, which in the illustrated embodiment is 40°.

[0039] As can be seen from Figs. 2 to 7, the ignition electrode wire 17 extends beyond the ground electrode 18, with the ignition electrode wire 17 intersecting the ground electrode 14 at an angle a in the top view of the vertical plane V-, as shown in Figs. 3 and 7.

[0040] The ignition electrode wire 17 is firmly integrated into the ignition electrode ceramic 15, such that a central longitudinal axis of the ignition electrode ceramic, as shown in the top view in Figures 3 and 7, forms an attachment point for the section of the ignition electrode wire 17 that projects beyond the end face of the ignition electrode ceramic 15. Since this section of the ignition electrode wire 17 is inclined to the vertical V3, as can be seen in Figures 3 and 7, and a center of gravity of the ignition electrode wire 17 is spaced apart from the attachment point on the electrode carrier 13, a gravitational force acts on the ignition electrode wire 17 at this center of gravity, which is spaced apart from the attachment point in the plane of curvature of the ignition electrode wire 17. This results in deformation due to aging during operation of the burner system 2 within the heating device 1, approximately along the downward-pointing arc F (Figure 7).Due to aging, the electrode tip 18 initially remains at a roughly constant distance from the sheath of the ground electrode 14 when deformed, until further deformation reduces the ignition distance. The arrow diagram is merely schematic, as a constant distance is not readily apparent in Fig. 7. As soon as the electrode tip 18, due to the deformation of the ignition electrode wire 17, approaches the sheath of the ground electrode 14 to such an extent that the electrode tip 18 and the sheath of the ground electrode 14 touch, ignition is no longer possible. This ensures a safe state for the burner system.

[0041] With the electrode arrangement 3 according to the invention, an aging-related increase in the distance between the electrode tip 18 and the sheath of the ground electrode 14, and thus an increase in the ignition energy required for ignition, can advantageously be avoided. Since the provided ignition energy is limited by the circuit design, an increase in ignition energy beyond its circuit-related limit, which would result from an increasing electrode distance, would lead to uncontrolled and unreliable ignition processes, potentially causing misfires and / or deflagrations.

Claims

Patent claims 1. Electrode arrangement (3) for a burner system (2) of a heating appliance (1), comprising an electrode carrier (13) which, in its ready-to-use assembled initial position, is aligned in a vertical plane (V) relative to the burner system (2), comprising a ground electrode (14) attached to the electrode carrier (13), comprising an ignition electrode (15, 17, 18) which has an ignition electrode wire (17) and an ignition electrode ceramic (15) holding the ignition electrode wire (17) and which is attached to the electrode carrier (13), characterized in that the ground electrode (14) is aligned at least largely parallel to the vertical plane (V^) of the electrode carrier (13), and that the ignition electrode ceramic (15) holding the ignition electrode wire (17) is attached to the electrode carrier (13) at least largely orthogonal to the vertical plane (V^) of the electrode carrier (13).and that the ignition electrode wire (17) protrudes from the ignition electrode ceramic (15) on an end face facing the electrode carrier (13) and curves towards its electrode tip (18) towards the ground electrode (14) in such a way that, in the event of age-related deformation of the ignition electrode wire (17), the electrode tip (18) moves in a path-like manner relative to the ground electrode (14) depending on gravity, so that an ignition distance to the ground electrode (14) remains constant and / or decreases.

2. Electrode arrangement (3) according to claim 1 , characterized in that the electrode tip (18) of the ignition electrode wire (17) is positioned at least largely in the plane of the ground electrode (14).

3. Electrode arrangement (3) according to claim 1 or 2, characterized in that in the ready-to-use initial position, a sheath of the ground electrode (14) and the electrode tip (18) of the ignition electrode wire (17) have an ignition gap of a range between 3.5 and 4.5 mm, preferably 4 mm, relative to each other.

4. Electrode arrangement (3) according to one of the preceding claims, characterized in that - with reference to the operationally assembled initial position - the ground electrode (14) - seen in a top view of the vertical plane (V^) - is inclined to a vertical (V3), and that the ignition electrode wire (17) projects in an arc over the ground electrode (14), wherein the ignition electrode wire (17) - seen in a top view of the vertical plane (V^) - intersects the ground electrode (14).

5. Electrode arrangement (3) according to claim 4, characterized in that the ground electrode (14) and the ignition electrode wire (17) - with reference to the operationally assembled initial position - are aligned relative to each other in an angle range between 43° and 58° with reference to the top view of the vertical plane (V^.

6. Electrode arrangement (3) according to claim 5, characterized in that the ground electrode (14) and the ignition electrode wire (17) - with reference to the operationally assembled initial position - are aligned at an angle of 53° relative to each other with reference to the top view of the vertical plane (V^.

7. Electrode arrangement (3) according to one of the preceding claims, characterized in that the ground electrode (14) is designed as a straight steel rod and is welded or soldered to a surface of the electrode carrier (13) in a lying position.

8. Electrode arrangement (3) according to one of the preceding claims, characterized in that the ignition electrode (15, 17, 18) is coupled to an ammeter (16) which measures an ionization current generated at the ignition electrode (15, 17, 18) during burner operation.

9. Burner system (2) for a heating appliance (1) with an electrode arrangement (3) according to one of the preceding claims.

10. Heating device (1) for a caravanning vehicle with a burner system (2) according to claim 9.

Images