Gas combustion device

TECHNICAL FIELD

The present invention relates to a gas combustion device for generating completely burnt hot air or warm air with high combustion efficiency using burning flame caused by, in particular, Liquefied Petroleum Gas (LPG) as a heat source.

BACKGROUND ART

Conventionally, a gas combustion device contained in devices such as portable hair driers and heat guns has been known.

In a gas combustion device contained in a hair drier, for example, a combustor for burning combustion gas (for example, LPG) is provided in a cylindrical casing of the hair drier. The combustor bums the combustion gas supplied from a gas tank as a source for the combustion gas and the air heated in a combustion chamber of the combustor is emitted to the side of a vent by a fan provided at the side of an inlet of the casing.

LPG as combustion gas is supplied from the gas tank to an ejector provided at the combustor. In the ejector, outside air necessary for combustion is sucked and mixed gas which consists of the combustion gas and the sucked air is generated. Thereafter, the mixed gas is injected from a wick (wire mesh) provide at the side of the inlet of the combustor. A spark is blown from an ignition plug (ignitor) to the wick and ignites the mixed gas.

The ignited burning flame burns in the combustion chamber so as to spread outwards from the wick and the combustion gas is discharged from an opened vent for combustion gas at an end ahead of the combustion chamber as warm air (refer to Japanese Patent Application Laid-open Publication No. 2002-233416).

In the conventional gas combustion device, the temperature of the combustion gas generated from the combustor tends to become high at its center part and low at its peripheral part. Especially when the gas combustion device is used for the hair drier or the like, outside air sent from an air-blower such as the fan provided at the hair drier passes laterally to the air heated by the combustor, causing the problem that the temperature of warm air at the center part becomes higher and the temperature of warm air at the peripheral part becomes lower.

Furthermore, when a large amount of the combustion gas is generated from the combustor, hot combustion gas and burning flame along with the air sent by the fan are easy to directly burst out of the combustor, causing a safety hazard.

To solve the above-mentioned problem, the present invention intends to provide a gas combustion device in which the temperature of warm air of the combustion gas discharged from the combustor is uniformed and which has high safety by preventing burst-out of burning flame.

DISCLOSURE OF THE INVENTION

To achieve the above-mentioned object, a gas combustion device comprises a combustion chamber for burning gas supplied from a gas source therein, a combustion gas vent for discharging combustion gas burnt in the combustion chamber, and a baffle member for adjusting distribution the combustion gas discharged from the combustion gas vent which is arranged at the combustion gas vent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a gas combustion device in accordance with an embodiment of the present invention taken along a line I-I in FIG. 2.

FIG. 2 is a front view of the gas combustion device viewed from the left side in FIG. 4.

FIG. 3A is a plan view of a baffle plate in accordance with the embodiment of the present invention.

FIG. 3B is a side view of the baffle plate in accordance with the embodiment of the present invention.

FIG. 4 is a side view of the gas combustion device in accordance with the embodiment of the present invention.

FIG. 5 is a sectional view taken along a line V-V in FIG. 1.

FIG. 6 is a back view of the gas combustion device viewed from the right side in FIG. 4.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to figures, an embodiment of the present invention will be described below.

With reference to FIG. 1, a gas combustion device 1 in accordance with this embodiment has an ejector 3 for generating mixed gas consisting of LPG, for example, as combustion gas and air, an electrode 5 as an ignitor for igniting the mixed gas generated by the ejector 3 and a combustor 7 for burning the mixed gas ignited by the electrode 5 therein.

Referring to FIGS. 4 to 6, a chamber 9 of the combustor 7 made of aluminum (die-cast) is a substantially cylindrical body with circular right and left side faces in the longitudinal direction of the chamber 7 in this embodiment as shown in FIGS. 5 and 6. The inside of the chamber 9 is comprised of a primary combustion chamber 11 located on the right side in FIG. 1 and a secondary combustion chamber 13 located ahead of the primary combustion chamber 11 (left side in FIG. 1). The ejector 3 is attached to the gas induction side in the rear of the primary combustion chamber 11 (right side in FIG. 1).

The ejector 3 is provided with a nozzle 19 for injecting gas supplied from a gas source such as a gas tank (not shown) for storing combustion gas such as LPG through a gas supply pipe 17 as a gas passage at the side of an inlet of a substantially cylindrical ejector body 15 having a circular cross section (right side in FIG. 1). A pin hole as an injection hole (not shown) having a bore diameter of φ60 μm to φ200 μm, for example, is provided at a front end of the nozzle 19. The injection hole is an orifice formed substantially in the center of a disc-like pin-hole disc (not shown) and LPG is thinly discharged at high speed close to sonic speed. A filter (not shown) for removing impurities and dusts which block the injection hole is provided in the nozzle 19. For example, a sintered metal with a pinhole having a diameter of 10 to 30 μm is used as the filter.

A mixer 21 for mixing the combustion gas (LPG) with a primary air and introducing the mixed gas into the combustor 7 is provided in the ejector body 15 ahead of the nozzle 19 and a primary air hole 23 for sucking the primary air penetrates a side wall of the mixer 21. Accordingly, the pressure in the mixer 21 becomes negative due to the combustion gas (LPG) discharged from the nozzle 19 at high speed, and the primary air is sucked from the outside. The sucked primary air is sent to a forward wick 25 as a gas combustion part while being mixed with the discharged combustion gas. This is called as an ejector effect. By adjusting area of the primary air hole 23, the ratio of the primary air can be adjusted.

The wick 25 as the gas combustion part is a cylindrical SUS metal mesh of 50 to 150 mesh, for example. The wick 25 is attached to the end ahead of the ejector body 15 by welding or the like substantially in the center of the right half of the primary combustion chamber 11 of the combustor 7 in FIG. 1. A wick holder 27 as a direct-advance suppression part is attached to the end ahead of the wick 25 by welding or the like.

The mixed gas discharged from the mixer 21 is guided mainly laterally (the direction shown by an arrow AR1 in FIG. 1) by the wick holder 27 and the mixed gas of the combustion gas (LPG) and air is discharged from the mesh of the wick 25. The flame after ignition is blue and substantially circular.

The electrode 5 is provided within the combustor 7 and ahead of the wick 25 and in the vicinity of the side face of the wick 25. High-tension electricity generated in a piezoelectric element for ignition (not shown) is input to the electrode 5 through an electric wire 29 and a spark is blown from the front end of the electrode 5 to the wick 25. The spark ignites the mixed gas discharged from the wick 25, thereby burning the mixed gas.

Referring to FIG. 5, on an inner wall of the primary combustion chamber 11, a plurality of groove parts 31 extending in the forward-rearward direction (horizontal direction in FIG. 1) are radially arranged around the wick 25. In FIG. 5, six groove parts 31 are formed.

A plurality of secondary air holes 33 for supplying outside air (secondary air) to the primary combustion chamber 11 are provided on a rear wall (right side wall in FIG. 1) of the primary combustion chamber 11. The plurality of secondary air holes 33 are disposed so that the secondary air is supplied to the mixed gas after ignition at the position other than an ignition point. The ignition point means the area where a spark generated by the electrode 5 can reach at the side of the electrode 5 in the periphery of the wick 25 as shown by an area surrounded by a dotted line in FIG. 5. In this embodiment, five secondary air holes 33 are provided.

A plurality of tertiary air ducts 35 as tertiary air holes for supplying outside air (tertiary air) to the secondary combustion chamber 13 are provided in the wall of the primary combustion chamber 11 between adjacent groove parts 31. In this embodiment, six tertiary air ducts 35 in total are provided.

A front end of the secondary combustion chamber 13 is opened and the opening forms a combustion gas vent 37 for discharging the combustion gas burnt in the secondary combustion chamber 13.

A plurality of fins 39 for heat exchange are provided in the outer periphery of the chamber 9. The fins 39 has the effect of emitting heat generated when the mixed gas is burnt in the chamber 9 and cooling the chamber 9, that is, performing heat exchange.

Next, a baffle member forming a main part of the embodiment of the present invention will be described.

Referring to FIGS. 1 and 2, a baffle plate 41 as the baffle member is a partition for adjusting distribution of the combustion gas discharged from the combustion gas vent 37 and attached with a claw part 43 which protrudes from the end face of the chamber 9, for example, so as to cover the whole of the combustion gas vent 37.

As shown in FIGS. 3A and 3B, the baffle plate 41, the periphery of which is substantially circular, is shaped like a circular disc and notched parts 45 each engaging with the claw part 43 are provided on four positions on the periphery. The baffle plate 41 is comprised of a center discharge hole 47 provided at about the center thereof and periphery discharge holes 49 provided on a virtual circle 51 surrounding the center discharge hole 47.

The center discharge hole 47 controls the direction of discharging the combustion gas so that the combustion gas in the secondary combustion chamber 13 is discharged from about the center of the combustion gas vent 37. The periphery discharge holes 49 control the direction of discharging the combustion gas so that the combustion gas is discharged from the part close to the inner wall of the secondary combustion chamber 13. In this embodiment, the center discharge hole 47 is a substantially circular through hole provided at about the center of the baffle plate 41 and the periphery discharge holes 49 are four elongated holes provided along the virtual circle 51 near the outer periphery of the baffle plate 41. The center discharge hole 47 is smaller than the periphery discharge hole 49 and most of the combustion gas is discharged from the periphery discharge holes 49.

The shape of the center discharge hole 47 and the periphery discharge holes 49 is not limited to the above-mentioned shape. For example, the periphery discharge holes 49 may be serially arranged along the virtual circle 51 near the outer periphery of the baffle plate 41 as a lot of circular through holes or may be formed in the other shape. The center discharge hole 47 may be formed to be smaller, formed as a plurality of holes or formed in the other shape.

With the above-mentioned configuration, when LPG is supplied into the nozzle 19 of the ejector 3 through the gas supply pipe 17, LPG passes through the filter in the nozzle 19 and injected from the injection hole as the orifice to the mixer 21 at the speed close to sonic speed. As a result, the pressure within the mixer 21 becomes negative due to the ejector effect and the primary air necessary for combustion (corresponding to the air-fuel ratio) is sucked from the primary air hole 23 and flows into the mixer 21. And then, the flowed primary air and LPG are mixed to form the mixed gas and the mixed gas is injected into the forward wick 25.

In the mixer 21, in proportion to increase or decrease in LPG, the primary air necessary for combustion is automatically sucked. Furthermore, by making the diameter of the primary air hole 23 small to decrease the amount of the primary air, the mixed gas with good ignitability is injected to the forward wick 25.

Since the wick holder 27 is provided at the forward end face in the wick 25, the combustion gas (mixed gas) is mainly injected from the SUS metal mesh on the side face to the periphery.

Next, by supplying high voltage from the piezoelectric element for ignition through the electric wire 29, a spark is generated from the electrode 5 in the combustor 7 and surely ignites the mixed gas with good ignitability emitted from the wick 25. Most of burning flame spreads outwards in a circle pattern from the side face of the wick 25 and the length of the burning flame remains to be ten-odd mm from the wick 25. Warm air is transmitted along the inside of the primary combustion chamber 11 and six groove parts 31 on the inner wall to the forward secondary combustion chamber 13.

At this time, since area of the primary air hole 23 is decreased to lower the ratio of the primary air, the mixed gas emitted from the wick 25 has good ignitability because of high gas ratio. Since the secondary air is supplied to the combustion gas after ignition from the secondary air hole 23, combustion efficiency of the gas in the primary combustion chamber 11 is improved, thereby improving combustion performance.

Furthermore, since outside air of much cooler than the mixed gas during combustion (tertiary air) passes through the six tertiary air ducts (tertiary air holes) 35, the temperature at the wall part of the primary combustion chamber 11 is effectively decreased. While the tertiary air supplied from the outside cools the wall part of the primary combustion chamber 11, the tertiary air exchanges heat with the wall part of the primary combustion chamber 11. Thus, the tertiary air is heated to high temperature while it passes through the tertiary air ducts 35. This heated tertiary air is introduced into the secondary combustion chamber 13. For this reason, combustion reaction of the gas in the secondary combustion chamber 13 is further promoted, thereby improving combustion performance. That is, since the gas burnt in the primary combustion chamber 11 and the hot tertiary air are mixed, combustion reaction easily occurs and complete combustion is promoted. This further improves combustion performance.

Since the baffle plate 41 is provided at the combustion gas vent 37 of the combustor 7, the combustion gas in the secondary combustion chamber 13 is discharged from the center discharge hole 47 and the periphery discharge holes 49. As a result, a difference in temperature between the center part and the peripheral part of the combustion gas is decreased. That is, the temperature of the combustion gas discharged from the combustor 7 is uniformed.

In this embodiment, since the center discharge hole 47 is formed to be smaller than the periphery discharge hole 49, most of the combustion gas is discharged from the periphery discharge holes 49 and a small amount of the combustion gas is discharged from the center discharge hole 47. For this reason, the combustion gas easily spreads over the discharged warm air. Thus, a difference in temperature between the center part and the peripheral part of the warm air becomes small.

Since the combustion gas is discharged from the periphery discharge holes 49 at the side of the periphery of the combustion gas vent 37, even when a large amount of the combustion gas and the burning flame occur in the primary combustion chamber 11 and the secondary combustion chamber 13, they are mixed with the peripheral air in the vicinity of the combustion gas vent 37, thereby that the burning flame is difficult to go outwards. Therefore, since the baffle plate 41 also suppresses burst-out of the burning flame, safety of the combustion device is improved.

The present invention is not limited to the above-mentioned embodiments and can be carried out according to the other aspects by making appropriate modifications. The gas combustion device 1 in accordance with this embodiment can be used as the gas combustion device such as a hair drier and a heat gun used for compression operation of a heat-shrinkable tube, drying, adhesion, fusing and soldering and the other gas combustion devices such as the other appliances.

INDUSTRIAL APPLICABILITY

According to the present invention, since the baffle member is provided at the combustion gas vent of the combustor, the temperature of the combustion gas discharged from the combustor can be uniformed and burst-out of the burning flame can be prevented.

Further, since the combustion gas is discharged from center discharge hole 47 and the periphery discharge holes 49, respectively, a difference in temperature between the center part and the peripheral part of the combustion gas becomes small. Furthermore, even when a large amount of the combustion gas and the burning flame occurs, since the combustion gas discharged from the periphery discharge holes is mixed with the peripheral air in the vicinity of the combustion gas vent, the burning flame can be prevented from going outwards.

Furthermore, since most of the combustion gas is discharged from the periphery discharge holes and a small amount of the combustion gas is discharged from the center discharge hole, the combustion gas easily spreads over the discharged warm air and a difference in temperature between the center part and the peripheral part of the warm air becomes small.

Gas combustion device

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