Combustion equipment and oil-fired water heaters

Abstract

To provide a combustor capable of stably performing discharging at the tip of an electrode rod even when oil adheres to the tip of the electrode rod.SOLUTION: A combustor comprises a first electrode rod having a first tip, a second electrode rod having a second tip, an auxiliary electrode, and a nozzle having an ejection port for ejecting liquid fuel. The first electrode rod and the second electrode rod are arranged so that the first tip and the second tip face each other with a space therebetween and the first tip and the second tip face the ejection port with a space therebetween. The auxiliary electrode is connected to the second electrode rod. The minimum distance between the auxiliary electrode and the first electrode rod is larger than the distance between the first tip and the second tip. The minimum distance between the auxiliary electrode and the nozzle is larger than the distance between the first tip and the second tip.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a combustion device and an oil-fired water heater. [Background technology]

[0002] For example, Japanese Patent Laid-Open No. 05-106840 (Patent Document 1) describes an ignition device. The ignition device described in Patent Document 1 has an insulator, an ignition electrode, and a target electrode. The ignition electrode and the target electrode are held by the insulator. The tip of the ignition electrode and the tip of the target electrode face each other with a gap between them. In the ignition device described in Patent Document 1, a voltage is applied between the tip of the ignition electrode and the tip of the target electrode, which generates a spark due to discharge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 05-106840 Summary of the Invention [Problem to be solved by the invention]

[0004] When the ignition device described in Patent Document 1 is used in, for example, a kerosene water heater, measures to improve ignition performance may be taken such as increasing the distance between the tip of the ignition electrode and the tip of the target electrode to lengthen the arc. However, if oil adheres to the tip of the ignition electrode or the tip of the target electrode, the voltage required to generate a discharge between the tip of the ignition electrode and the tip of the target electrode increases, making it difficult to generate a discharge between the tip of the ignition electrode and the tip of the target electrode.

[0005] The present invention has been made in consideration of the above-mentioned problems of the prior art. More specifically, the present invention provides a combustion device that can stably discharge electricity at the tip of the electrode rod even if oil adheres to the tip of the electrode rod. [Means for solving the problem]

[0006] A combustion device according to one aspect of the present invention includes a first electrode rod having a first tip, a second electrode rod having a second tip, an auxiliary electrode, and a nozzle having an ejection port for ejecting liquid fuel. The first electrode rod and the second electrode rod are arranged so that the first tip and the second tip face each other with a gap therebetween and so that the first tip and the second tip face the ejection port with a gap therebetween. The auxiliary electrode is connected to the second electrode rod. The minimum value of the distance between the auxiliary electrode and the first electrode rod is greater than the distance between the first tip and the second tip. The minimum value of the distance between the auxiliary electrode and the nozzle is greater than the distance between the first tip and the second tip.

[0007] In the combustion device, the minimum value of the distance between the first electrode rod and the auxiliary electrode may be 1.5 times or more and 5.0 times or less the distance between the first tip and the second tip.

[0008] In the combustion device, the minimum value of the distance between the auxiliary electrode and the nozzle may be 1.5 times or more the distance between the first tip and the second tip.

[0009] In the combustion device, the auxiliary electrode may have corners. In the combustion device, the auxiliary electrode may be a plate-shaped member. The thickness of the auxiliary electrode may be 0.3 mm or more and 1.0 mm or less.

[0010] The combustion device may further include an electrode mounting plate and an insulating member. The electrode mounting plate may have a through hole formed therein that penetrates the electrode mounting plate in the thickness direction. The insulating member may have an insertion portion that passes through the through hole when attached to the electrode mounting plate, and may hold the first electrode rod and the second electrode rod such that a portion of the first electrode rod having a first tip and a portion of the second electrode rod having a second tip protrude from the insertion portion. The first electrode rod and the second electrode rod may be aligned in a first direction. The first tip and the second tip may face the nozzle with a gap in a second direction perpendicular to the first direction. The insertion portion may include a first end and a second end opposite the first end in the first direction. The insertion portion may include a first surface and a second surface opposite the first surface in a third direction perpendicular to the first and second directions. The auxiliary electrode may be located between the first end and the second end in a front view along the third direction. In a side view along the first direction, the auxiliary electrode may be positioned within a region that is perpendicular to the central axis of the second electrode rod and that is formed by moving a virtual straight line that passes through the part of the insertion portion where the distance between the first surface and the second surface is greatest to the second tip while maintaining the virtual straight line perpendicular to the central axis.

[0011] An oil-fired water heater according to one aspect of the present invention includes the combustion device described above. [Effects of the Invention]

[0012] According to the combustion device and oil-fired water heater of one aspect of the present invention, stable discharge can be achieved at the tip of the electrode rod even if oil adheres to the tip of the electrode rod. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a front view of a combustion device 100. [Figure 2] FIG. 1 is a first side view of a combustion device 100. [Figure 3] FIG. 2 is a second side view of the combustion device 100. [Figure 4]FIG. 2 is a plan view of the electrode mounting plate 50. [Figure 5] FIG. 1 is a side view of a combustion device 100 having a nozzle 60. [Figure 6] FIG. 2 is a front view of the combustion device 200. DETAILED DESCRIPTION OF THE INVENTION

[0014] The details of an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant description will not be repeated. A combustion device according to an embodiment of the present invention is referred to as a combustion device 100.

[0015] (Configuration of combustion device 100) The configuration of the combustion device 100 will be described below.

[0016] FIG. 1 is a front view of the combustion device 100. In FIG. 1, the position of the nozzle 60 is indicated by a dotted line. FIG. 2 is a first side view of the combustion device 100. The nozzle 60 is not shown in FIG. 2. FIG. 3 is a second side view of the combustion device 100. The nozzle 60 is not shown in FIG. 3. As shown in FIGS. 1 to 3, the combustion device 100 has a first electrode 10, a second electrode 20, an insulating member 30, and an auxiliary electrode 40. The combustion device 100 is a combustion device used in, for example, an oil-fired water heater. The oil-fired water heater may include a water heater having at least one of a hot water supply function, a bath water supply function, a bath reheating function, and a hot water heating function. For example, even a water heater dedicated to hot water heating is included in the oil-fired water heater. The combustion device 100 may be a combustion device used in an oil-fired boiler.

[0017] The first electrode rod 10 and the second electrode rod 20 are made of a conductor. The first electrode rod 10 and the second electrode rod 20 are made of, for example, a metal material. The first electrode rod 10 and the second electrode rod 20 are arranged adjacent to each other in the first direction DR1.

[0018] The first electrode rod 10 has a first distal end 11 and a first proximal end 12. The first proximal end 12 is the end opposite the first distal end 11. The second electrode rod 20 has a second distal end 21 and a second proximal end 22. The second proximal end 22 is the end opposite the second distal end 21. The first distal end 11 and the second distal end 21 face each other with a gap in between in the first direction DR1.

[0019] The first electrode rod 10 has a first portion 13 and a second portion 14. The first portion 13 extends along the second direction DR2. One end of the first portion 13 corresponds to the first base end 12. The second direction DR2 is a direction perpendicular to the first direction DR1. The other end of the first portion 13 is connected to one end of the second portion 14. The second portion 14 extends linearly. The other end of the second portion 14 corresponds to the first tip 11. The outer diameter of the end of the second portion 14 on the first tip 11 side becomes smaller as it approaches the first tip 11.

[0020] In a side view taken along the first direction DR1, the second portion 14 is inclined such that its position in the third direction DR3 moves away from the first portion 13 as it approaches the first tip 11. The third direction DR3 is a direction perpendicular to the first direction DR1 and the second direction DR2. In a front view taken along the third direction DR3, the second portion 14 is inclined such that its position in the first direction DR1 moves away from the first portion 13 toward the second electrode rod 20 as it approaches the first tip 11.

[0021] The second electrode rod 20 has a third portion 23 and a fourth portion 24. The third portion 23 extends along the second direction DR2. One end of the third portion 23 corresponds to the second base end 22. The other end of the third portion 23 is connected to one end of the fourth portion 24. The fourth portion 24 extends linearly. The other end of the fourth portion 24 corresponds to the second tip 21. The outer diameter of the end of the fourth portion 24 on the second tip 21 side decreases as it approaches the second tip 21.

[0022] In a side view taken along the first direction DR1, the fourth portion 24 is inclined such that its position in the third direction DR3 moves away from the third portion 23 as it approaches the second tip 21. In a front view taken along the third direction DR3, the fourth portion 24 is inclined such that its position in the first direction DR1 moves away from the third portion 23 toward the first electrode rod 10 as it approaches the second tip 21.

[0023] The insulating member 30 is made of an electrically insulating material. The insulating member 30 is made of, for example, a resin material. The insulating member 30 has an insertion portion 31. The insertion portion 31 is a portion of the insulating member 30 that passes through a through-hole 51 (described later) when the insulating member 30 is attached to an electrode attachment plate 50 (described later).

[0024] The insertion portion 31 has a first end 31a and a second end 31b in the first direction DR1. The second end 31b is the end opposite to the first end 31a. The insertion portion 31 has a first surface 31c and a second surface 31d in the third direction DR3. The first surface 31c is the surface facing the nozzle 60 described below. The second surface 31d is the surface opposite to the first surface 31c.

[0025] The insulating member 30 holds the first electrode rod 10 and the second electrode rod 20. The portion of the first electrode rod 10 on the first tip 11 side (part of the first portion 13 and the second portion 14) protrudes from the lower end of the insulating member 30 (the lower end of the insertion portion 31). The portion of the first electrode rod 10 on the first base end 12 side (part of the first portion 13) protrudes from the upper end of the insulating member 30. The portion of the second electrode rod 20 on the second tip 21 side (part of the third portion 23 and the fourth portion 24) protrudes from the lower end of the insulating member 30 (the lower end of the insertion portion 31). The portion of the second electrode rod 20 on the second base end 22 side (part of the third portion 23) protrudes from the upper end of the insulating member 30.

[0026] The auxiliary electrode 40 is made of a conductor. The auxiliary electrode 40 is made of, for example, a metal material. The auxiliary electrode 40 is connected to the second electrode rod 20. More specifically, the auxiliary electrode 40 is connected to a portion of the second electrode rod 20 (for example, a part of the third portion 23) that protrudes from the lower end of the insulating member 30 (the lower end of the insertion portion 31).

[0027] The auxiliary electrode 40 has, for example, a rectangular shape with its longitudinal direction aligned with the first direction DR1 when viewed from the front in the third direction DR3. From another perspective, the auxiliary electrode 40 has corners. The auxiliary electrode 40 has a third surface 40a and a fourth surface 40b. The third surface 40a and the fourth surface 40b are end surfaces of the auxiliary electrode 40 in the thickness direction. The thickness direction of the auxiliary electrode 40 is aligned with the third direction DR3. The third surface 40a faces the nozzle 60 (described later). The fourth surface 40b is the surface opposite the third surface 40a. The auxiliary electrode 40 is connected to the second electrode rod 20 at the fourth surface 40b. The thickness of the auxiliary electrode 40 is preferably 0.3 mm or more and 1.0 mm or less. Although the auxiliary electrode 40 appears to be in contact with the first electrode rod 10 in FIG. 2, the auxiliary electrode 40 is not in contact with the first electrode rod 10 (see, for example, FIG. 1).

[0028] At least a portion of the surface of the third portion 23 may have a flat surface. For example, the cross-sectional shape of at least a portion of the third portion 23 may be D-shaped with a straight portion. The auxiliary electrode 40 is attached to the third portion 23 so that this flat surface contacts the fourth surface 40b. In this case, it is easy to position the auxiliary electrode 40 relative to the second electrode rod 20.

[0029] The minimum value of the distance between the auxiliary electrode 40 and the first electrode rod 10 is greater than the distance between the first tip 11 and the second tip 21. The minimum value of the distance between the auxiliary electrode 40 and the first electrode rod 10 is preferably 1.5 times or more the distance between the first tip 11 and the second tip 21. The minimum value of the distance between the auxiliary electrode 40 and the first electrode rod 10 is preferably 5.0 times or less the distance between the first tip 11 and the second tip 21.

[0030] The auxiliary electrode 40 is preferably disposed between the first end 31a and the second end 31b in the first direction DR1. In a side view along the first direction DR1, the auxiliary electrode 40 is preferably disposed within a region (region indicated by a dotted line in FIG. 3 ) that is formed by moving a virtual line that is perpendicular to the central axis of the second electrode rod 20 and that passes through the portion of the insertion portion 31 where the distance between the first surface 31c and the second surface 31d is greatest to the second tip 21 while maintaining the virtual line perpendicular to the central axis of the second electrode rod 20.

[0031] FIG. 4 is a plan view of the electrode mounting plate 50. As shown in FIG. 4, the combustion device 100 further includes an electrode mounting plate 50. The electrode mounting plate 50 is a plate-shaped member. A through hole 51 and a through hole 52 are formed in the electrode mounting plate 50. The through hole 51 and the through hole 52 penetrate the electrode mounting plate 50 in the thickness direction. The insertion portion 31, the portion of the first electrode rod 10 protruding from the lower end of the insertion portion 31, the portion of the second electrode rod 20 protruding from the lower end of the insertion portion 31, and the auxiliary electrode 40 are passed through the through hole 51. This allows the insulating member 30 to be attached to the electrode mounting plate 50. A nozzle 60, which will be described later, is attached to the through hole 52. The through hole 51 and the through hole 52 are arranged adjacent to each other in the third direction DR3.

[0032] Fig. 5 is a side view of the combustion device 100 having a nozzle 60. As shown in Fig. 5, the combustion device 100 further has the nozzle 60. The nozzle 60 extends along the second direction DR2. The tip (lower end) of the nozzle 60 forms an ejection port 61, and liquid fuel is ejected from the ejection port 61. The first tip 11 and the second tip 21 are arranged to face the ejection port 61 at an interval in the second direction DR2.

[0033] The minimum value of the distance between the nozzle 60 and the auxiliary electrode 40 is greater than the distance between the first tip 11 and the second tip 21. It is preferable that the minimum value of the distance between the nozzle 60 and the auxiliary electrode 40 be 1.5 times or more the distance between the first tip 11 and the second tip 21.

[0034] (Effects of the combustion device 100) The effects of the combustion device 100 will be described below.

[0035] In the combustion device 100, an AC voltage is applied between the first electrode rod 10 and the second electrode rod 20 so that the voltage at the first tip 11 and the voltage at the second tip 21 are opposite in polarity. This generates an electric field between the first tip 11 and the second tip 21, which stimulates electron emission from the first tip 11 and the second tip 21, generating an electric arc due to discharge between the first tip 11 and the second tip 21. When this electric arc comes into contact with the liquid fuel ejected from the ejection port 61, the liquid fuel is ignited.

[0036] Because the combustion device 100 is used in an oil-fired water heater or an oil-fired boiler, oil (kerosene) may adhere to the first tip 11 and the second tip 21. When oil adheres to the first tip 11 and the second tip 21, electrons are less likely to be emitted from the first tip 11 and the second tip 21, and an electric arc due to discharge may not occur between the first tip 11 and the second tip 21. In other words, when oil adheres to the first tip 11 and the second tip 21, ignition of the liquid fuel may fail.

[0037] However, in the combustion device 100, because the auxiliary electrode 40 is connected to the second electrode rod 20, an electric field is also generated between the auxiliary electrode 40 and the first tip 11. The electric field generated between the auxiliary electrode 40 and the first tip 11 promotes electron emission from the first tip 11. Therefore, according to the combustion device 100, even if oil is attached to the first tip 11 and the second tip 21, a stable discharge is likely to occur between the first tip 11 and the second tip 21.

[0038] In the combustion device 100, the minimum distance between the auxiliary electrode 40 and the first electrode rod 10 is greater than the distance between the first tip 11 and the second tip 21, so discharge is unlikely to occur between the auxiliary electrode 40 and the first tip 11. In the combustion device 100, the minimum distance between the nozzle 60 and the auxiliary electrode 40 is greater than the distance between the first tip 11 and the second tip 21, so discharge is unlikely to occur between the auxiliary electrode 40 and the nozzle 60.

[0039] When the minimum distance between the auxiliary electrode 40 and the first electrode rod 10 is 1.5 times or more the distance between the first tip 11 and the second tip 21, it is more difficult for a discharge to occur between the auxiliary electrode 40 and the first tip 11. When the minimum distance between the auxiliary electrode 40 and the first electrode rod 10 is 5.0 times or less the distance between the first tip 11 and the second tip 21, the auxiliary electrode 40 can sufficiently promote electron emission from the first tip 11. When the minimum distance between the nozzle 60 and the auxiliary electrode 40 is 1.5 times or more the distance between the first tip 11 and the second tip 21, it is more difficult for a discharge to occur between the auxiliary electrode 40 and the nozzle 60.

[0040] When the auxiliary electrode 40 has a corner, electric field concentration is likely to occur at the corner, so even if oil is attached to the first tip 11 and the second tip 21, discharge is more likely to occur stably between the first tip 11 and the second tip 21.

[0041] If the thickness of auxiliary electrode 40 is 1.0 mm or less, electric field concentration is likely to occur, and even if oil is attached to first tip 11 and second tip 21, discharge is more likely to occur stably between first tip 11 and second tip 21. If the thickness of auxiliary electrode 40 is 0.3 mm or more, the strength of auxiliary electrode 40 can be ensured.

[0042] 3 , even if the dimensions of the through hole 51 are approximately the same as those of the insertion portion 31, the insertion portion 31, the portion of the first electrode rod 10 protruding from the lower end of the insertion portion 31, the portion of the second electrode rod 20 protruding from the lower end of the insertion portion 31, and the auxiliary electrode 40 can all pass through the through hole 51. As a result, in this case, the gap between the insertion portion 31 and the through hole 51 is reduced, and the positional accuracy of the first tip 11 and the second tip 21 is improved, thereby preventing ignition failures caused by the electric arc generated between the first tip 11 and the second tip 21 not coming into contact with the liquid fuel ejected from the ejection port 61.

[0043] (Discharge test) A discharge test was conducted to confirm the effect of the combustion device 100. In addition to the combustion device 100, a combustion device according to a comparative example (hereinafter referred to as "combustion device 200") was also used in this discharge test. FIG. 6 is a front view of the combustion device 200. The nozzle 60 is not shown in FIG. 6. As shown in FIG. 6, the combustion device 200 does not have an auxiliary electrode 40. In other respects, the configuration of the combustion device 200 is the same as that of the combustion device 100. This discharge test was conducted with the nozzle 60 removed.

[0044] In this discharge test, an AC voltage of 90 volts and a frequency of 60 Hz was applied between the first electrode rod 10 and the second electrode rod 20. This AC voltage was applied for 30 minutes, with each set consisting of a 5-second on state and a 5-second off state. In other words, the AC voltage was applied 180 times under the above conditions. Before this discharge test was conducted, the combustion device 100 and the combustion device 200 were immersed in kerosene and then pulled out, so that the first tip 11 and the second tip 21 of the first electrode rod 10 and the second electrode rod 20 protruding from the lower end of the insertion part 31 were covered with kerosene.

[0045] In the combustion device 100 and the combustion device 200, the distance between the first tip 11 and the second tip 21 was set to 3.6 mm. Furthermore, in the combustion device 100, the minimum distance between the auxiliary electrode 40 and the first electrode rod 10 was set to 7.5 mm.

[0046] The results of this discharge test are shown in Table 1. As shown in Table 1, in the combustion device 200, discharge failure occurred 74 times out of 180 applications of AC voltage. On the other hand, in the combustion device 100, discharge failure occurred zero times out of 180 applications of AC voltage. From this comparison, it was experimentally revealed that by including the auxiliary electrode 40 in the combustion device 100, even if oil is attached to the first tip 11 and the second tip 21, discharge is likely to occur stably between the first tip 11 and the second tip 21.

[0047] [Table 1]

[0048] Although the embodiments of the present invention have been described above, the above-described embodiments can be modified in various ways. Furthermore, the scope of the present invention is not limited to the above-described embodiments. The scope of the present invention is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Industrial Applicability]

[0049] The above-described embodiment is particularly advantageously applicable to a combustion device and an oil-fired water heater or oil-fired boiler having the same. [Explanation of symbols]

[0050] 10 first electrode rod, 11 first tip, 12 first base end, 13 first portion, 14 second portion, 20 second electrode rod, 21 second tip, 22 second base end, 23 third portion, 24 fourth portion, 30 insulating member, 31 insertion portion, 31a first end, 31b second end, 31c first surface, 31d second surface, 40 auxiliary electrode, 40a third surface, 40b fourth surface, 50 electrode mounting plate, 51, 52 through hole, 60 nozzle, 61 ejection port, 100, 200 combustion device, DR1 first direction, DR2 second direction, DR3 third direction.

Claims

1. a first electrode rod having a first tip; a second electrode rod having a second tip; An auxiliary electrode; a nozzle having an ejection port for ejecting the liquid fuel, the first electrode rod and the second electrode rod are arranged such that the first tip and the second tip face each other with a gap therebetween and also such that the first tip and the second tip face the jet port with a gap therebetween, the auxiliary electrode is connected to the second electrode rod, a minimum value of the distance between the auxiliary electrode and the first electrode rod is greater than a distance between the first tip and the second tip; A combustion device, wherein a minimum value of the distance between the auxiliary electrode and the nozzle is greater than a distance between the first tip and the second tip.

2. 2. The combustion device according to claim 1, wherein a minimum value of the distance between the first electrode rod and the auxiliary electrode is 1.5 to 5.0 times the distance between the first tip and the second tip.

3. 3. The combustion device according to claim 1, wherein a minimum value of the distance between the auxiliary electrode and the nozzle is 1.5 times or more the distance between the first tip and the second tip.

4. 4. The combustion device according to claim 1, wherein the auxiliary electrode has a corner.

5. the auxiliary electrode is a plate-shaped member, 5. The combustion device according to claim 1, wherein the thickness of the auxiliary electrode is 0.3 mm or more and 1.0 mm or less.

6. an electrode mounting plate; an insulating member; a through hole penetrating the electrode mounting plate along a thickness direction thereof is formed in the electrode mounting plate; the insulating member has an insertion portion that passes through the through hole when attached to the electrode attachment plate, and holds the first electrode rod and the second electrode rod such that a portion of the first electrode rod having the first tip and a portion of the second electrode rod having the second tip protrude from the insertion portion, the first electrode rod and the second electrode rod are aligned in a first direction, the first tip and the second tip face the ejection port with a gap in a second direction perpendicular to the first direction, the insertion portion includes a first end and a second end opposite to the first end in the first direction, the insertion portion includes a first surface and a second surface opposite to the first surface in a third direction perpendicular to the first direction and the second direction, the auxiliary electrode is located between the first end and the second end in a front view along the third direction, 6. The combustion apparatus according to claim 1, wherein, in a side view seen along the first direction, the auxiliary electrode is disposed within a region that is formed by moving a virtual line that is perpendicular to a central axis of the second electrode rod and that passes through a part of the insertion portion where the distance between the first surface and the second surface is greatest, to the second tip while keeping the virtual line perpendicular to the central axis.

7. A kerosene water heater comprising the combustion device according to any one of claims 1 to 6.

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