Hot air generating heater and its insulator

Abstract

To provide a heater which can continuously discharge a hot wind at around 500°C to 1,200°C and an insulator.SOLUTION: A hot air generation heater has a plurality of insulators 20 arrayed in a housing, a spirally wound heating wire 15 is inserted into a plurality of gas circulation holes 25 formed in the insulators 20, and air is supplied to a supply port of the housing and high-temperature hot air is discharged from a discharge port. Shapes of the gas circulation holes 25 are formed such that their vertical lengths are longer than left-and-right lengths in front view. Fore-and-aft ridge parts 23 are formed in ceiling parts and bottom face parts of the gas circulation holes 25 in a gas circulation direction, and one or more than one vertical ridge parts 24 are formed in both right and left side parts of the gas circulation holes 25 in a vertical direction. As a result, the fore-and-aft ridge parts 23 provided in the ceiling parts and the bottom face parts supports an upper edge part and a lower edge part of the heating wire 15 and the vertical ridge parts 24 formed in both the right and left side parts are positioned between spiral pitches of the heating wire 15. The insulators are arrayed substantially in parallel with one another with prescribed intervals maintained in the gas circulation direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heater for generating hot air that can be connected to a blower or the like to continuously discharge high-temperature hot air at approximately 1200°C, and to an insulator used therefor. [Background technology]

[0002] A conventional hot air generating heater of this type and a basic example of an insulator used in this heater are shown in the attached Figures 10 and 11. Figure 10 is a perspective explanatory view of the insulator, and Figure 11 is a conceptual explanatory view of the hot air generating heater. The insulator 70 shown in Figure 10 is a so-called lotus root insulator having a cylindrical shape, and has a number of gas flow holes 75, 75, ... formed in its axial direction, and a spirally wound heating wire made of a resistance heating alloy is wired in each of the gas flow holes 75.

[0003] The blown gas flows in the axial direction (gas flow direction) D, passes through each of the gas flow holes 75, and is heated. No protrusions or projections for supporting the heating wire are provided on the inner wall surface of each of the gas flow holes 75. A suitable number of these insulators 70 are arranged in the axial direction, overlapped with the gas flow holes 75 aligned, and then placed inside the heater for generating hot air.

[0004] FIG. 11 shows a heater 80 for generating hot air, in which the insulator 70 is disposed. Inside a heater housing 83 having a gas supply port 81 on the right end side in the figure and a hot air discharge port 82 on the left end side in the figure, four of the insulators 70 are arranged in series in the axial direction (gas flow direction D) and fixed.

[0005] The number of insulators 70 to be arranged is determined appropriately depending on the capacity of the heater. When arranging the insulators 70, the positions of the gas communication holes 75 of each are arranged in the same position. Then, as shown by the two-dot chain line in the figure, the heating wire is wired in these gas communication holes 75 from the supply port 81 side toward the discharge port 82, and then wired sequentially in a zigzag pattern from the discharge port 82 side toward the supply port 81 side. By making the number of gas communication holes 75 of the insulator 70 an even number, both terminals of the heating wire can be arranged on the supply port side.

[0006] Each insulator 70 is fixed by a long bolt 86 and a nut 87. These bolts and nuts are fixed using any two to four of the gas communication holes 75 provided in the insulator 70. Although not shown, a temperature sensor such as a thermocouple for preventing abnormal overheating can be disposed in one of the gas communication holes 75 located in the central portion. In this case, the sensor is disposed by inserting it through the center of the spirally wound heating wire. A discharge temperature sensor T for detecting the discharge temperature is disposed from the outside of the heater housing 83 in front of the insulator located closest to the discharge port side in the heater housing 83.

[0007] The problems with the above conventional example can be listed as follows: The heating wires wired into the insulators stretch in the direction of the load due to a sudden increase in the amount of air being blown (a change in the air speed passing through the gas flow holes) or gravity (causing unevenness in the distance (pitch) between adjacent spirally wound heating wires), which causes abnormal overheating and changes the amount of air passing through each gas flow hole, making it impossible to safely discharge high-temperature hot air for long periods of time.

[0008] When high-temperature hot air of 800°C or higher is discharged, the surface temperature of the heating wire reaches approximately 900°C or higher, and the wind pressure of the blown gas causes the heating wire to extend toward the insulator's discharge port. This problem of the extension of the heating wire can be exacerbated by the vibration of the heating wire caused by a magnetic field that is generated when a current is passed through the heating wire.

[0009] Vibration of the heating wire is caused not only by magnetic fields but also by mechanical vibrations. Such vibrations cause frictional contact between the heating wire and the gas flow holes, which causes the oxide film on the heating wire to be scraped off (polished) or the inner wall surface of the insulator to be polished. This turns into dust that flies out and has a negative impact on the environment, and if this dust accumulates in the gas flow holes, it can cause the heating wire to break. The heating wire is not held in place by the insulator sufficiently, making it vulnerable to mechanical or magnetic vibrations.The heating wire is simply inserted into the gas flow holes of the insulator and routed there, so it is not held in place by the insulator.

[0010] In order to solve the above problems, the inventor of the present application previously proposed the invention described in Patent Document 1 below. The invention described in Patent Document 1 below aims to provide a heater for generating hot air that can continuously discharge high-temperature hot air of about 800°C to 1000°C by devising a combination of insulator and heating wire, without the insulator itself holding the heating wire.The objective was to further reduce the weight, conserve resources, make it more compact, and reduce costs, while also improving performance compared to conventional heaters, that is, to improve the heat exchange efficiency with the blown gas and make it possible to obtain a continuously discharged gas temperature higher than conventional heaters.

[0011] The heater is configured to have an insulator placed inside a roughly cylindrical heater housing with a gas supply port at one end and an outlet at the other end, and electric heating wires arranged in multiple gas flow holes in the insulator.The blown gas supplied from a blower or the like through the supply port is heated by circulating it through the gas flow holes in the insulator, and high-temperature hot air is discharged from the outlet.The insulators are formed from multiple circular plate-shaped insulators of a predetermined thickness, and the gas flow holes are arranged in the axial direction.The multiple insulators are arranged in a row in the blowing direction, approximately parallel to each other and spaced apart, with the spacing between them being approximately 1 / 2 to 2 times the thickness of the insulators.

[0012] To briefly explain heating elements (heating wires) and their lifespan, austenitic resistance alloys are generally used when heating air. Various manufacturers sell a variety of these heating elements, but materials sold for industrial use have a maximum continuous operating temperature specified as a severe operating condition.

[0013] However, it is often difficult to predict the lifespan of a heating element in relation to temperature, as it is influenced by a variety of factors, such as the method of supporting the heating element, fluctuations in ambient temperature, temperature changes and vibration of the heating element caused by turning the voltage on and off, the electrical insulation value of the insulator, and high-quality fire-resistant insulators (containing 40% or more alumina), and if these are selected and designed without understanding them, all of these will shorten the lifespan of the heating element.

[0014] In addition, the heating element (resistance heating alloy) forms an oxide film on its surface, which helps to extend the life of the heating element. However, this film is thin and must be protected from peeling due to vibrations caused by the vent gas passing through the gas flow holes in the insulator.

[0015] It is also necessary to be careful that the heating element inserted into the gas flow hole of the insulator does not come into point contact with the insulator, as point contact will cause friction that exceeds the wear limit, causing the oxide film in that area to wear away or disappear, and even scraping away the surface of the heating element, changing the electrical resistance of that area and having a severe adverse effect on the lifespan.

[0016] As described above, from the viewpoint of the lifespan of the heating element, the heating element and the insulator have a very close relationship, and this must be taken into consideration when considering the configuration and structure of the insulator and the heater for generating hot air.

[0017] Therefore, the inventors of the present application filed a patent application under Patent Application No. 2020-112236 on June 30, 2020, with the aim of providing not only a relatively small high-temperature hot air generating heater like the above-mentioned conventional examples, but also a hot air generating heater and insulator therefor that can continuously discharge high-temperature hot air (approximately 500°C to 1100°C) that can be easily upgraded from a small capacity to a larger capacity, and to solve the various problems that existed with the above-mentioned conventional hot air generating heaters and insulators.

[0018] However, even with the heater according to the above-mentioned invention, although it was possible to obtain hot air of 1000°C or more in the laboratory, when hot air of such a high temperature was continuously discharged, various problems occurred, such as melting of the heating element and cracking of the insulator, and for commercial use the maximum discharge temperature was limited to 900°C. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-57892 Summary of the Invention [Problem to be solved by the invention]

[0020] Therefore, in the present invention, similar to the above patent application invention, the objective is to provide not only a relatively small high-temperature hot air generating heater like the conventional examples, but also a hot air generating heater and insulator therefor that can continuously discharge (for commercial operation) high-temperature hot air (approximately 500°C to 1200°C) and can be easily upgraded from a small capacity to a larger capacity, and to solve the various problems that have existed with the above conventional hot air generating heaters and insulators. In the laboratory, high-temperature hot air can be discharged at approximately 1300°C, but the purpose of this application is to provide a device that can discharge hot air in the above temperature range, which is suitable for commercial operation, i.e., can be operated continuously without any problems. [Means for solving the problem]

[0021] In order to solve the above problems, the first aspect of the present invention is a hot air generation heater that has a plurality of insulators arranged in a housing, a spirally wound heating wire inserted into a plurality of gas flow holes provided in these insulators, and that can supply air from a supply port in the housing and discharge high-temperature hot air from the discharge port, and the shape of the gas flow hole is formed so that the vertical length is longer than the horizontal length when viewed from the front, and longitudinal ridges are formed in the gas flow direction on the upper and lower ceiling and bottom surfaces of the gas flow hole, and one or more vertical ridges are formed in the vertical direction on both the left and right side surfaces of the gas flow hole, so that the longitudinal ridges on the ceiling and bottom surfaces can support the upper and lower edges of the heating wire, and the vertical ridges on both the left and right side surfaces are positioned between the pitches of the spirally wound heating wire, and the insulators are arranged approximately parallel to each other while maintaining a predetermined interval in the gas flow direction.

[0022] The second aspect of the present invention is the first aspect of the present invention, wherein the outer shape of the insulator when viewed from the front is a substantially rectangular shape, the gas flow holes are vertically elongated substantially rectangular shapes when viewed from the front, and a plurality of the gas flow holes are arranged vertically and horizontally when viewed from the front, In the single insulator, the central portions above and below the horizontally aligned gas flow holes are divided in the horizontal direction to form constituent divided insulators of approximately the same shape, and these constituent divided insulators are then stacked together to form the single insulator, Furthermore, the central portion of each of the constituent divided insulators is divided horizontally to form unit divided insulators, The heater for generating hot air is characterized in that the single insulator is formed by stacking these unit divided insulators one on top of the other.

[0023] The third aspect of the present invention is a heater for generating hot air, characterized in that, in the second invention, recesses are provided on the upper and lower surfaces of the constituent divided insulators of the insulator, and further, gaps are formed in the middle part excluding both end parts where the lower surface and upper surface of the constituent divided insulator are joined, and gaps are provided in the middle part excluding both end parts at the joint part between the unit divided insulators on the gas flow hole side.

[0024] The fourth aspect of the present invention is a heater for generating hot air, characterized in that, in the first to third inventions, the vertical length of the gas flow hole is between two and three times the outer diameter of the heating element.

[0025] A fifth aspect of the present invention is a heater for generating hot air according to any one of the first to fourth aspects of the present invention, characterized in that the heater capacity can be changed by arranging the single insulator in parallel in the vertical and / or horizontal directions.

[0026] A sixth aspect of the present invention is a heater for generating hot air, characterized in that, in each of the above-mentioned inventions, the intervals between the insulators arranged in the gas flow direction are set to become narrower toward the discharge port.

[0027] The seventh aspect of the present invention is a heater for generating hot air, characterized in that, in the second to sixth inventions above, a plurality of sensor insertion holes for inserting temperature sensors such as thermocouples are provided in the gas flow direction on the joining surfaces where the constituent divided insulators are joined.

[0028] The eighth aspect of the present invention is an insulator used in a hot air generating heater, which has a plurality of insulators arranged in a housing, a plurality of gas circulation holes provided in these insulators through which a spirally wound heating wire is inserted, and which can supply air from a supply port of the housing and discharge high-temperature hot air from its discharge port, and in which the shape of the gas circulation hole of the insulator is formed so that the vertical length is longer than the horizontal length when viewed from the front, and longitudinal ridges are formed in the gas circulation direction on the upper and lower ceiling and bottom surfaces of the gas circulation hole, respectively, and one or more vertical ridges are formed in the vertical direction on both the left and right side surfaces of the gas circulation hole, so that the longitudinal ridges provided on the ceiling and bottom surfaces support the upper and lower edges of the heating wire. and the insulator for a hot air generation heater is characterized in that the insulator can support a heater, and the vertical protrusions provided on both the left and right side surfaces are arranged at intervals between the pitches of the spirally wound heating wire, the outer shape of the insulator when viewed from the front is approximately rectangular, the gas flow holes are approximately rectangular and vertically elongated when viewed from the front, and a plurality of them are aligned vertically and horizontally when viewed from the front, the upper and lower central portions of the horizontally aligned gas flow holes are divided horizontally to form constituent divided insulators of approximately the same shape, and these are stacked together to form the single insulator, and further the central portions of each constituent divided insulator are divided horizontally to form unit divided insulators, and these unit divided insulators are stacked together vertically to form the single insulator.

[0029] The ninth aspect of the present invention is an insulator for a heater for generating hot air, characterized in that, in the eighth invention described above, recesses are provided in the upper and lower surfaces of the constituent divided insulators of the insulator, and further, gaps are formed in the middle part excluding both end parts on the front and back sides where the lower and upper surfaces of the constituent divided insulators are joined, and gaps are provided in the middle part at the joint between the unit divided insulators excluding both end parts on the front and back sides.

[0030] The tenth aspect of the present invention is an insulator for a heater for generating hot air as described in the eighth or ninth invention, characterized in that the vertical length of the gas flow hole is between two and three times the outer diameter of the heating element.

[0031] The eleventh aspect of the present invention is an insulator for a heater for generating hot air, characterized in that, in the eighth to tenth inventions described above, a plurality of sensor insertion holes for inserting temperature sensors such as thermocouples are provided in the gas flow direction on the joining surfaces where the constituent divided insulators are joined.

[0032] The twelfth aspect of the present invention is directed to the divided insulator itself that constitutes the insulator of the heater for generating hot air described in the eighth aspect of the present invention.

[0033] The thirteenth aspect of the present invention is directed to the unit divided insulator itself that constitutes the insulator of the heater for generating hot air described in the eighth aspect of the present invention. [Effects of the Invention]

[0034] In the first aspect of the present invention, the shape of the gas flow hole of the insulator is formed so that its vertical length is longer than its horizontal length when viewed from the front, and longitudinal ridges are formed in the gas flow direction on the upper and lower ceiling and bottom surfaces of the gas flow hole, respectively, and one or more vertical ridges are formed in the vertical direction on each of the left and right side surfaces of the gas flow hole.As a result, the longitudinal ridges on the ceiling and bottom surfaces can properly support the upper and lower edges of the heating wire, and the vertical ridges on the left and right side surfaces are positioned between the pitches of the spirally wound heating wire, preventing the heating wire from extending forward (towards the outlet).

[0035] Furthermore, by making the vertical length of the gas flow hole greater than the lateral length, the efficiency of heat exchange from the heating wire to the blown gas is improved to the maximum. This overturns the conventional concept of improving heat exchange efficiency by narrowing the gap between the outer surface of the heating wire (the surface of the outer edge of the wound heating wire) and the inner wall surface of the insulator and forcing gas to circulate within that gap, as was revealed by subsequent experimental results.

[0036] Furthermore, since the insulators arranged in the gas flow direction are spaced apart at predetermined intervals, the heated blown gas in the gas flow holes of each insulator is mixed and blended between the insulators once. This mixing and blending of the blast gas between the insulators eliminates temperature variations (temperature differences) within each gas flow hole of the blast gas, realizing a constant temperature rise. This process is repeated in the spaces between each insulator, resulting in an improved heat exchange efficiency for the blast gas. Furthermore, the spacing between the insulators allows the amount of air passing through each gas flow hole to be approximately the same, further improving the efficiency of heat transfer from the heating wire to the blown gas.

[0037] The air sent from the blower is connected to the heater for generating hot air using a duct or similar. The blown gas flows through multiple gas flow holes in the insulator, but the air speed (air volume, temperature) passing through each gas flow hole is not necessarily constant. If the balance is lost, there may be a temperature difference, with the hot air passing through one gas flow hole being 700°C and another being 660°C. When this happens, the blown gas mixes and becomes uniform in the next space between the insulators. By repeating this process two, three or more times, the temperature (air volume, air speed) in all gas flow holes becomes almost completely the same.

[0038] In the second aspect of the present invention, the insulator in the first aspect of the present invention is further limited. That is, the outer shape of the insulator when viewed from the front is approximately rectangular, the gas flow holes are approximately rectangular and vertically elongated when viewed from the front, and are arranged in multiple rows vertically and horizontally when viewed from the front, and in one insulator, the upper and lower central portions of the horizontally aligned gas flow holes are divided horizontally to form constituent divided insulators of approximately the same shape, which are then stacked together to form one insulator, and further, the central portions of each constituent divided insulator are divided horizontally to form unit divided insulators, and these unit divided insulators are stacked together vertically to form one insulator. This makes it easy to wire the heating wire to the insulator, and simplifies the assembly of the heater.

[0039] In the third aspect of the present invention, the shapes of the constituent divided insulators and the unit divided insulators are further limited. That is, recesses are provided in the upper and lower surfaces of the constituent divided insulators, and further, gaps are formed in the middle part excluding both end parts where the lower surface and upper surface of the constituent divided insulators are joined, and gaps are also provided in the middle part excluding both end parts at the joint part between the unit divided insulators on the gas flow hole side, thereby making it possible to make the insulator thinner and taking into account its thermal expansion, etc.

[0040] In the fourth embodiment of the present invention, the shape of the gas flow holes of the insulator is also limited, that is, the vertical length of the gas flow holes is limited to the range of 2 to 3 times the outer diameter of the heating element. If the vertical length of the gas flow holes is increased beyond this range, the efficiency of heat exchange with the blown gas decreases, and conversely, if it is decreased, the same problems as in the conventional example occur and the heat exchange efficiency also decreases.

[0041] In the fifth aspect of the present invention, it is specified that the heater capacity can be easily changed by fixing a plurality of the set of insulators in parallel in the vertical and / or horizontal directions when viewed from the front.

[0042] In the sixth aspect of the present invention, the spacing between the insulators arranged in the gas flow direction is set to become narrower as they approach the outlet, making it applicable to heaters that generate hot air at higher temperatures.

[0043] In the seventh aspect of the present invention, a plurality of sensor insertion holes for inserting temperature sensors such as thermocouples are provided in the gas flow direction at the joining surfaces where the constituent divided insulators are joined, thereby enabling more accurate temperature measurement at desired positions.

[0044] The eighth aspect of the present invention claims the insulator itself used in the heater specified in the first and second inventions above, and its effects are the same as those of the first and second inventions above.

[0045] The ninth aspect of the present invention claims the constituent divided insulators and unit divided insulators themselves used in the heater specified in the third invention above, and its effects are the same as those of the third invention above.

[0046] The tenth aspect of the present invention specifies that the vertical length of the gas flow holes of the insulator is between two and three times the outer diameter of the heating element inserted inside, and specifies the form of the insulator with the best heat exchange efficiency.

[0047] The eleventh aspect of the present invention is characterized in that a plurality of sensor insertion holes for inserting temperature sensors such as thermocouples are provided in the gas flow direction on the joining surfaces where the constituent divided insulators are joined, and its effect is the same as that of the seventh invention described above.

[0048] The twelfth aspect of the present invention is a claim relating to a component divided insulator that constitutes the insulator according to the eighth aspect of the present invention.

[0049] The thirteenth aspect of the present invention is a claim relating to a unit divided insulator that constitutes the insulator according to the eighth aspect of the present invention. [Brief explanation of the drawings]

[0050] [Figure 1] 1 shows the appearance of one embodiment of a heater for generating hot air according to the present invention, with the outlet portion thereof removed. [Figure 2] 2A and 2B show an insulator provided in the heater according to the embodiment, in which FIG. 2A is a cross-sectional view (a plan view of a unit divided insulator), FIG. 2B is a front view, and FIG. 2C is a partial vertical cross-sectional view. [Figure 3] The unit divided insulators constituting the above-mentioned insulator are shown, with (A) being a front view, (B) being a plan view, (C) being a bottom view, (D) being a right side view, and (E) being an E-E cross-sectional view of (A). [Figure 4] 4A and 4B show another embodiment of the unit split insulator, in which FIG. 4A is a front view and FIG. 4B is a bottom view. [Figure 5]The figure shows the heater for generating hot air and the insulator for the prototype 1, (A) is a conceptual explanatory front view from the outlet side of the heater (with the outlet part separated), (B) is a conceptual explanatory side view, (C) is a plan view of the insulator, and (D) is a front view of the insulator. [Figure 6] The insulator used in prototype 2 is shown in the figure, with (A) being a front view, (B) being a side view (the left and right side views are identical), and (C) being a plan view (the same as the bottom view). [Figure 7] 10 is a graph showing experimental results of prototype 1. [Figure 8] 10 is a graph showing experimental results of prototype 2. [Figure 9] 10 is a graph showing experimental results of prototype 3 according to the embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view illustrating a conventional insulator. [Figure 11] FIG. 11 is a conceptual explanatory diagram showing a conventional heater for generating hot air in which the insulator shown in FIG. 10 is disposed inside. DETAILED DESCRIPTION OF THE INVENTION

[0051] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, the development process leading to the present invention will be outlined, including experimental methods.

[0052] Prototype 1 relates to the invention of the above-mentioned Japanese Patent Application No. 2020-112236 (described later in FIG. 5). Prototype 2 uses an insulator with a cross-sectional shape of the gas flow hole of the insulator used in Prototype 1 (by narrowing the space between the outer edge surface of the heating wire and the wall surface of the gas flow hole), which is divided horizontally into six sections (described later in Figure 6). Prototype 3 is a heater for generating hot air that uses the insulator according to the present invention.

[0053] Performance tests were conducted using the insulators used in these three prototypes and insulating materials with different performance surrounding the insulators, and the results are shown below. Regarding the material of the heating element (heater wire / heating wire) used, design factors related to life were taken into consideration, and a heating element material with a heat resistance effect of 1300°C to 1350°C was used as the maximum common temperature of the heating element, taking into account a safety factor.

[0054] The insulator material is selected to have excellent physical properties in various ways, and since the heating element is fixed and held in place by the insulator, the shape is designed taking into consideration the wall load of the insulator as well as the wind speed and pressure loss of the gas passing around it.

[0055] <About Prototype 3 (the present invention)> (Regarding the performance of the products we sell) During repeated experiments, it was discovered that there were various user requests for the temperature of the outlet, and that the amount of air passing through the insulator could also be changed, and that a product was required that could be used without changing the maximum temperature of the hot air discharged from the outlet even when these conditions changed. For example, there may be cases where you want to start discharging high-temperature hot air almost immediately after starting the unit, or where you want to maintain the initially set discharge temperature even if you reduce the air volume drastically during operation. Therefore, it is necessary to attach temperature sensors to the product body in several locations near the heating element and individually control the temperature of each part in advance to solve problems such as overheating or wire breakage in the heating element.

[0056] <Problems identified in prototypes 1 and 2> About Prototype 1 When manufacturing insulators for hot air generators, considerations are given to thermal properties (maximum operating temperature), electrical properties (dielectric strength), mechanical properties (compression and bending strength), cross-sectional shape with consideration to breathability (which affects air flow), method of holding the heating element, heat exchange efficiency between the heating element and gas (air), production costs, etc., but when the insulators of Prototype 1 were tested, when the surface temperature exceeded 900°C, the limit of the insulator's mechanical properties was exceeded and cracks occurred in the insulators. Naturally, to prevent cracks, slits (1 mm wide) were made in the problematic areas, but it was decided that this would only be installed in products with a hot air generation temperature of up to 800°C.

[0057] About Prototype 2 Next, in prototype 2, the insulator shape was designed to eliminate the problems of prototype 1. The insulator material was also improved by blending about 50% alumina-based material. Compared to Prototype 1, the cross-sectional area of the insulator passing around the heating element (outer surface) was reduced by about 10%. It was hoped that this would increase the air speed passing through the heating element and improve the heat exchange efficiency, but the test run revealed that when 1000°C hot air was generated, the highest temperature part of the heating element reached over 1300°C. The cause was that infrared rays emitted from the heating element were transmitted to the insulator, causing the temperature of the insulator to rise abnormally, which tended to reduce the efficiency of heat exchange between the essential heating element and the gas. With prototype 2, the limits of the shape that could be devised to hold or support the heating element became apparent, so a new insulator was designed and invented, and prototype 3 according to the present invention was completed.

[0058] About Prototype 3 Generally, when voltage is applied to both ends of a heating element in a windless environment, the surface of the heating element heats up and its temperature rises, at the same time emitting infrared rays. If the voltage is further increased, the temperature of the heating element itself rises and the amount of infrared rays emitted from the heating element also increases. It is nearly impossible to directly heat the air using only these infrared rays, so one idea is to take in the infrared rays on the surface of the insulator, heat the insulator, and exchange heat with the air there, but when we conducted a test run with the insulator shape of the above prototype 2, the temperature of the outer surface of the heating element rose too much, causing the heating element to melt, because the distance between the outer surface of the heating element and the insulator was too short. Naturally, the entire insulator also became hot due to the infrared rays, and the test results showed that the hot air temperature on the discharge port side could only reach 1050°C.

[0059] Therefore, further improvements were made and prototype 3 was produced. The shape of the insulator used here was conceived by the inventor of this application, and although the reason for choosing this shape was merely a "whimselfish idea," it is the result of the inventor's experience of more than 50 years in the manufacture and sale of electric heaters. This prototype 3 was designed to address the problems with prototypes 1 and 2. First, the upper and lower dimensions of the gas flow holes in the insulator were lengthened to prevent the heat generated by the heating element from being trapped in the insulator.

[0060] Furthermore, the insulators have been made as thin as possible to reduce mass and have a shape that takes production costs into consideration. At the same time, the heater capacity (amount of heating element loaded) has been increased by 1.4 times so that it can be used in large models. When high-temperature hot air is generated, the heated gas (air) flows into the insulator, comes into contact with the heating element, and the gas presses against the heating element, but to prevent the force (wind pressure) pushing against the gas from pushing out (moving) the heating element that has become softened due to the high temperature, multiple vertical ridges are provided on the wall surface of the gas flow hole where the heating element is loaded. Furthermore, these vertical ridges have made it possible for the heating element to be used in any direction, not just horizontally.

[0061] That is, in prototype 3, the shape of the gas flow hole for supporting the heating element was improved, and the shape that holds the heating element was made a vertically long rectangle with a width slightly larger than the outer diameter of the heating element. Because there was a margin, four ridges (the number can be arbitrary) were provided in the insulator passage as described above to prevent the heating element from being pushed (moved) by wind pressure.

[0062] We left as much space as possible between the heating element and the insulator, but past tests have shown that if this space is left too large, the efficiency of heat exchange between the heating element and the air decreases. On the other hand, if this space is too small, problems will arise, as shown in the test results of Prototype 2. With the above configuration, the test run of Prototype 3 showed excellent performance. The test run results of prototype 3 and others will be shown later.

[0063] Hereinafter, an embodiment (prototype 3) of the heater for generating hot air according to the present invention will be described in detail. FIG. 1 shows the appearance of one embodiment of a heater for generating hot air according to the present invention, with the outlet portion removed. FIG. 2 shows an insulator provided in the heater according to the embodiment, where (A) is a cross-sectional view (a plan view of a unit divided insulator), (B) is a front view, and (C) is a partial vertical cross-sectional view.

[0064] The heater for generating hot air according to the present invention comprises a rectangular parallelepiped housing 10 that is long from front to back, and insulators 20 shown in FIG. 2 are arranged in parallel with each other at a predetermined distance in the direction of gas flow. In FIG. 1, the front side (lower left side) of the housing 10 is the discharge port side, and the opposite side is the gas supply port side.

[0065] Inside the housing 10, a set of insulators 20 (also referred to as "one block") shown in FIG. 2 are arranged in parallel at predetermined intervals in the flow direction of the gas to be heated. That is, a plurality of gas flow holes 25 of the insulator 20 are arranged at predetermined intervals so that the front-rear direction (gas flow direction) of the gas flow holes 25 coincides with the gas flow direction of the housing 10 . The spirally wound heating wire 15 is wired inside the gas flow hole 25 (not shown in FIG. 1).

[0066] As can be seen from FIG. 2, the insulator 20 has six gas flow holes 25 arranged horizontally and three arranged vertically, and the upper and lower middle parts of the gas flow holes 25 arranged horizontally are divided horizontally (horizontally) to form constituent divided insulators 22, and further, the approximate center of the middle part of this constituent divided insulator 22 is divided horizontally (horizontally) into two to form unit divided insulators 21.

[0067] That is, two unit divided insulators 21 are aligned with each other at the sides of their gas flow holes 25 to form a constituent divided insulator 22, and three of these constituent divided insulators 22 are stacked one on top of the other to form one set (one block) of insulator 20. The reason for forming one block of insulator using six unit divided insulators 21 in this way is to make it easier to wire the heating wire 15 inside the gas flow hole 25, to make assembly easier, and to make the thickness of the wall of the insulator 21 that supports the heating wire 15 thinner. The insulator used in Prototype 1 consisted of one single block, and as will be explained later, it was not possible to provide a space between the top and bottom of the horizontally aligned gas flow holes.

[0068] In the present invention, the shape of the gas communication holes 25 is different from that of the conventional ones. That is, its front view shape is a vertically elongated, approximately rectangular shape, and in the front-to-rear direction (gas flow direction) of approximately the center of its ceiling and bottom parts, front-to-rear protrusion parts 23 are provided, which protrude toward the center of the gas flow hole 25. These longitudinal protrusions 23, 23 support the upper and lower edges of the spirally wound heating wire 15.

[0069] On the other hand, two vertical protrusions 24 extending vertically and protruding toward the center of the gas communication hole 25 are provided on each of the two side surfaces of the gas communication hole 25 . The vertical protrusions 24, 24 provided on both side surfaces fit into the pitch of the spirally wound heating element 15, preventing the heating wire 15 from moving toward the discharge port side.

[0070] 2(B), the gas communication holes 25 have a vertically long, approximately rectangular shape, forming large spaces above and below the heating wire 15. In this embodiment, the distance between the top and bottom of the gas communication holes 25 is set to about twice the outer diameter of the wound heating wire 15.

[0071] As described above, the heater for generating hot air according to the present invention is configured by arranging a plurality of the above-mentioned blocks of insulators 20 in parallel and substantially parallel to the gas flow direction inside the substantially rectangular parallelepiped housing 10. The blocks are arranged with appropriate intervals between them, and although the intervals between the blocks may be uniform, it is preferable to set the intervals to become gradually narrower toward the ejection port.

[0072] FIG. 3 shows a unit divided insulator that constitutes the above-mentioned insulator, where (A) is a front view, (B) is a plan view, (C) is a bottom view, (D) is a right side view, and (E) is an E-E cross-sectional view of FIG. (A).

[0073] The shape of the unit divided insulator 21 can be clearly seen from this figure. Two of the unit divided insulators 21 shown in this figure are stacked symmetrically vertically, i.e., so that the openings of their gas flow holes 25 are united; in other words, one of the unit divided insulators 21 is rotated 180 degrees and united to form the above-mentioned component divided insulator 22, and three of these component divided insulators 22 are stacked vertically to complete one block of insulator 20.

[0074] As can be clearly seen from the front view of FIG. 3(A), a long longitudinal protrusion 23 is provided at an appropriate height in the center of the bottom surface of each gas flow hole 25 in the longitudinal direction (gas flow direction). This is to maintain a larger gap between the top and bottom of the heating wire.

[0075] As can be clearly seen from the plan view of FIG. 3(B), two vertical protrusions 24, 24 are formed on both side surfaces of the gas flow port 25 in the vertical direction. These vertical protrusions 24 , 24 are formed to fit the pitch of the spiral of the heating wire wired inside the gas flow hole 25 .

[0076] As can be clearly seen from the bottom view of FIG. 3(C), a recess 26 is provided in the bottom surface of the unit split insulator 21, which allows the thickness of the insulator to be made thinner. By forming this recess 26, a space can be formed between the constituent divided insulators 22 of one block of insulator 20, allowing the wall of the insulator to be made thinner and also reducing the manufacturing cost.

[0077] The vertical recess 28 between the pair of vertical protrusions 27, 27 at both ends, which is clearly visible in the plan view and bottom view, is used when stacking and fixing these unit divided insulators 21 one above the other within the housing.

[0078] Here, we will explain the placement of temperature sensors for controlling the heater temperature. In order to develop a good product (high-temperature hot air of 1000°C or higher), it is important to measure the temperature of each part. There are three important measurement points that affect heater performance, and if the measurements of these three points are uncertain, the product sold will suffer from fatal problems.

[0079] The temperature measurement points are as follows: 1. Hot air temperature at the outlet (hot air temperature required by the customer) 2. Temperature of the tip of the heating wire (discharge port area) (the hottest point of the heating element) 3. The hottest point on the insulator that supports the heating wire at the tip

[0080] The test results will be shown later, but it can be seen that in Prototype 3 according to the present invention, the temperature difference in the measurement results of each of the above points 1 to 3 is much smaller than in Prototypes 1 and 2. This means that the efficiency of the insulator is very good.

[0081] Furthermore, with regard to heating elements, there has been no technical information available up until now on how to use commercially available industrial heating elements (ferrite-based resistance alloys) to generate high-temperature hot air (over 1000°C). The basic design for the use of heating elements is stated by heating element manufacturers, and the key points of electric furnace design include the atmosphere of the gas to be heated, the furnace temperature to be used, the furnace power, the furnace voltage, the wall load (furnace area), the surface load of the heating element relative to the furnace temperature, and the shape of the heating element (in the case of wound wire, the core diameter relative to the wire diameter, etc.). However, there is no data available on the market that applies to hot air generators. A simple example available to the public is to use a conventional heating element and insulator, insert the heating element into the insulator, and then blow gas (ordinary indoor air) into it with a blower. Hot air will easily come out the outlet, and the purpose will be achieved.

[0082] <Advantages of the insulator of Prototype 3 (present invention)> However, as a manufacturer of industrial hot air generators, we are aware that user requirements are rapidly changing, including the need to improve pressure loss when sending gas to insulators and heating elements, and the requirement for high hot air temperatures of 800°C, then 900°C, then 1000°C, and currently the required discharge temperature is increasing to over 1100°C. And important requirements such as efficiency, lifespan, and safety are required.

[0083] The above prototype 1 was used for experiments for about two years, also using conventional insulators. When high-temperature hot air was discharged, hot air of over 1000°C was discharged within the short experimental period, but the result was that some of the cordierite-based insulators (heat-resistant temperature 1250°C or higher) melted.

[0084] In the above-mentioned prototype 2, an alumina-based material (heat-resistant temperature 1500°C) was used, and it was possible to obtain high-temperature hot air of over 1100°C, but at this point the temperature of the insulator reached around 1250°C, and part of the heating element melted (maximum allowable heating element temperature 1400°C). In other words, it is thought that the thermal energy inside the heating element could not be dissipated properly, causing it to melt.

[0085] Normally, one way for gas to absorb the energy of a heating element is to increase the speed of the gas coming into contact with the heating element, which will lower the temperature of the heating element and increase the temperature of the gas. However, with the shape of the conventional insulators (insulators of prototype 1 and prototype 2), it seems that it would have been difficult to generate high-temperature hot air even if the speed of the gas coming into contact with the heating element was increased.

[0086] Therefore, as will be seen from the experimental results shown later, we decided to significantly change the shape of the insulator. As mentioned above, insulators for heaters used to generate hot air are determined by measuring (1) the hot air temperature at the outlet, (2) the surface temperature of the heating element at that time, and (3) the surface temperature of the insulator at that location. Naturally, the smaller the difference between the temperatures (1) to (3), the more appropriate the shape of the insulator to be used for high-temperature hot air.

[0087] When electricity is applied to a heating element, the surface temperature of the heating element rises, and if the surface temperature exceeds 1000°C, if there is no wind on the surface of the heating element, heat and intense infrared rays are emitted. The infrared rays heat the insulator, and the temperature of the insulator becomes higher than that of the heating element.

[0088] Therefore, in the prototype 3 according to the present invention, the gas flow holes are made vertically rectangular, as shown in FIGS. A coiled heating element was placed inside the enclosure, and in order to stably support it in the center, thin, vertical pillars were used to support the heating element, while there was also some space left in the left and right gaps. However, if the heating element was left in this state, the coil would be pushed and moved by the wind pressure, so protrusions were added in two places, one on top and one on bottom. When the heating wire coil repeatedly moves and pulsates, it rubs against the insulator, damaging the oxide coating that affects the coil's lifespan.

[0089] The heating element used in the experiment had a wire diameter of 3.5 mm, which was spirally wound to give the heating element an inner diameter of 17 mm and an outer diameter of 24 mm. The heating element pitch was 3.9 mm, the watt density was 3.1 W / mm2, the operating voltage was 200 V, and the experiment was conducted using prototype 3 with a heater capacity of 28 kW.

[0090] As can be seen from the drawing, the ideal shape for an insulator for generating high-temperature hot air is one in which the outer cross-sectional area of the spiral coil of the heating element is about twice the inner cross-sectional area (see the shaded area in Figure 2(B)). Next, it was found that the cross-sectional area of the vertically elongated rectangle should ideally be about 2.5 to 3 times the outer cross-sectional area of the spiral coil. On the other hand, if it is increased by more than four times, the heating element will overheat and melt.

[0091] Below, the experimental results for Prototype 1, Prototype 2, and Prototype 3 according to the present invention will be explained. Figure 5 shows the hot air generating heater and insulator of prototype 1, where (A) is a conceptual explanatory front view from the outlet side of the heater (with the outlet portion separated), (B) is a conceptual explanatory side view, (C) is a plan view of the insulator, and (D) is a front view of the insulator.

[0092] The insulator 50 of the prototype 1 has a generally rectangular shape when viewed from the front, and is provided with fixing recesses 51, 51 in the vertical direction on both sides thereof, and is made of a ceramic material such as cordierite. In the direction of the paper of this insulator 50 (gas flow direction / see Figures 5(A)(D)), there are arranged three vertically and four horizontally, for a total of 12 gas flow holes 55 through which the blown gas flows, aligned vertically and horizontally. Each gas communication hole 55 has a substantially circular cross section.

[0093] As can be seen from Figure 5(D), eight protrusions 53 are provided on the inner wall surface of this gas flow hole 55 at equal intervals in the circumferential direction in the gas flow direction, and eight grooves 54 are also formed between these protrusions 53.

[0094] The support surfaces of these protrusions 53 that support the heating wire 20 are formed to be substantially flat, and are in surface contact with the heating wire 20 . Although not shown, an austenitic resistance heating alloy is used as the heating wire. Due to the presence of the groove portions 54 between the protrusion portions 53, the blown gas is forced into the gas flow holes 55, where it is forced into contact with the inner and outer periphery of the heating wire, thereby removing heat from the heating wire and, at the same time, more effectively removing heat from the protrusion portions 53 of the insulator 50.

[0095] In FIG. 5(D), two through holes 56, 56 are provided in each area surrounded by four gas flow holes 55, for a total of 12 holes in total. These holes 56 are holes for arranging temperature sensors such as thermocouples, and any of these holes 56 can be used to appropriately arrange a temperature sensor for detecting the maximum temperature, the temperature of the discharged air, etc. As can be seen from FIG. 5(B), five insulators 50 are arranged in the housing in the gas flow direction D, substantially parallel to each other.

[0096] The intervals k1 to k4 between the five insulators 50 are widest on the supply port 5 side and gradually narrower toward the discharge port side, with the interval k4 closest to the discharge port being the narrowest.

[0097] In the prototype 1 configured as described above, the blown gas from a blower or the like is supplied from a supply port 58 via piping or a duct, forced into a plurality of gas flow holes 55 provided in the insulator 50, heated, and discharged in the direction of arrow D from a discharge port (not shown) on the left end side of the figure.

[0098] Figure 6 shows the insulator used in Prototype 2, with (A) being a front view and (B) being a (A) is the side view (the left and right side views are identical), and (C) is the top view (the same as the bottom view). In this prototype 2, like the insulator according to the present invention, the overall shape is substantially rectangular, and four gas flow holes 65 are arranged horizontally and three gas flow holes are arranged vertically and horizontally.

[0099] As can be seen from the front view, the shape of the gas flow hole 65 has two front-rear protrusions 63, 63 at the top and bottom, and also has low front-rear protrusions 64, 64 on the left and right sides, with a recessed rib portion 66 formed between these front-rear protrusions 63 and 64. The blown gas flows through these grooves 66 and removes heat from the outer periphery of the heating wire.

[0100] The space between the outer periphery of the wound heating wire and the recessed streak portion 66 was designed to be about 10% smaller in cross-sectional area than the prototype 1. The purpose of this was to improve the efficiency of heat exchange from the heating wire to the blown gas or to the insulator, but as already mentioned, this has actually resulted in a decrease in efficiency.

[0101] Furthermore, in this prototype 2, as in the present invention, the above-mentioned insulator 60 is divided horizontally into six parts to form unit divided insulators 61, two of these unit divided insulators 61 are stacked together so that the openings of their gas flow holes 65 match up to form a constituent divided insulator 62, and three of these constituent divided insulators 62 are stacked one on top of the other to form a set of insulators 60. As a result, a recess 68 is formed on the bottom or top surface of each unit divided insulator 61 .

[0102] As shown in the front view, small gaps 70 are provided at the upper and lower joints (front and rear ends) between the component segment insulators 62, except for both ends. Similarly, at the joining surfaces where the unit divided insulators 61 are joined together, a gap 69 is provided at the front end and rear end except for both end portions.

[0103] Of course, these gaps 69 and 70 may be provided in the insulator 20 of the present invention. Furthermore, two sensor through holes 71 for temperature sensors such as thermocouples are provided in the center of the gap 69 when viewed from the front. It should be noted that this prototype 2 was produced during the process of completing the present invention, and was not commercialized. With the completion of the present invention, plans to commercialize it were also abandoned.

[0104] In the insulator according to the present invention disclosed in FIGS. 2 and 3, the gaps 69, 70 and the through-hole 71 for a temperature sensor such as a thermocouple are also essential components as required. Therefore, the unit divided insulator of prototype 3 according to the present invention, which is provided with the sensor through-hole 71 and the like, is shown in FIG.

[0105] FIG. 4 shows a unit divided insulator of the present invention, (A) being a front view and (B) being a bottom view. In FIG. 4, the gaps 69 and 70 provided in the prototype 2 are not shown, but it is possible to provide them.

[0106] In this unit divided insulator 21, the sensor through-hole 71 is formed by laser processing after the unit divided insulator 21 is molded. Because the insulator wall thickness is thin, this part can be formed in an instant using a laser processing machine. Similarly, the temperature measuring hole 72 provided on the bottom surface of the unit divided insulator 21 can be machined in an instant because the wall thickness of the insulator is thin.

[0107] Conventionally, in the method of measuring the temperature of the heating wire surface of a large hot air generator, a lead wire is inserted into a small-diameter, two-hole insulating tube for insulating the thermocouple wire, and then the tube is inserted directly into the center of the spirally wound heating wire from the gas supply port side.

[0108] The advantage of this method is that the temperature of the heating wire can be measured reliably. On the other hand, the disadvantage is that the lifespan of the thermocouple is shortened because both the lead wires and the two-hole insulating tube are exposed to high temperatures. If the diameter of the lead wire is increased, the outer diameter of the insulating tube also increases, the cross-sectional area through which the blown gas flows decreases, and the efficiency of heat conduction to the blown gas also decreases, resulting in an imbalance.

[0109] In the prototype 2 and the prototype 3 according to the present invention, the through-hole 71 for the temperature sensor is provided separately from the gas communication hole 25 . The insulators of prototype 1 are general-purpose products, and each insulator has 12 through holes for sensors so that the thermocouple can be set anywhere.

[0110] In the prototype 3 according to the present invention, it is not necessary to provide the sensor insertion holes 71 in all of the unit split insulators 21, and temperature measurement holes 72 can be post-processed by laser processing only in the necessary locations to accurately capture the surface temperature of the heating element. It has also been found that providing such a temperature measurement hole 72 for temperature measurement is extremely ideal.

[0111] Hot start operation is a process in which a small amount of current is passed through the heating element in a windless state to accumulate heat in the heater. For example, if you store heat at 600°C and then start blowing air, hot air at about 500°C can be discharged almost instantly.

[0112] The temperature rise time is shortened, resulting in significant energy savings. Customers may request a hot start temperature of 800°C or 950°C, and in such cases, it becomes necessary to incorporate several thermocouples as individual temperature sensors inside the heating element as a safety circuit to meet the customer's requirements.

[0113] Therefore, it is not necessary to provide the temperature sensor insertion hole 71 in all of the insulators according to the present invention. FIG. 4 shows four sensor insertion holes 71 and one temperature measurement hole 72, but these can be laser processed according to the number of sensors as needed.

[0114] Figure 4(B) shows the temperature measurement hole 72, and the heating wire 15 is wired just below this temperature measurement hole 72. No ventilation gas flows through the area where the thermocouple is wired, making it the ideal place to install the sensor. This type of sensor placement method is the first of its kind in the industry. When the wire diameter of the thermocouple is large, the size of the insertion hole 71 and the temperature measurement hole 72 can be easily processed by changing the design to the desired size as appropriate.

[0115] The prototypes 1 to 3 used in the test run are outlined below, and the test results are summarized in Table 1.

[0116] [Table 1]

[0117] FIG. 6 is a graph showing the experimental results of the prototype 1. FIG. 7 is a graph showing the experimental results of the second prototype. FIG. 8 is a graph showing the experimental results of prototype 3 according to the above embodiment of the present invention. In the figure, A indicates the hot air temperature at the outlet, B indicates the heating wire surface temperature (at the outlet), and C indicates the insulator temperature (at the outlet).

[0118] As can be clearly seen from the above three graphs, in prototype 3 of the present invention, the outlet hot air temperature (a), the heating element surface temperature (b), and the insulator temperature (c) are almost close to each other, and it was found that the heat exchange efficiency from the heating wire to the blown gas is extremely good compared to prototypes 1 and 2. Although not shown in Table 1 above, the final experimental results for the insulator of Prototype 3 above were as follows: (a) The temperature of the hot air at the outlet was 1277°C, (c) the temperature around the insulator at that time was 1350°C, and (b) the temperature of the heater (heating wire coil) was 1293°C. In other words, (c)-(b) / 1350-1293=57, meaning that the temperature difference between the insulator and the heating wire was only 57°C, and we were able to obtain excellent results.

[0119] Although the embodiment of the present invention has been described above, the present invention can be modified in various ways as follows. In the above embodiment, six gas flow holes are provided in the horizontal direction and three gas flow holes are provided in the vertical direction in one block of the insulator, but the number of gas flow holes in the vertical and horizontal directions can be changed as appropriate.

[0120] What is important is that the above-mentioned one block of insulators is divided equally at the same height horizontally, and if three gas flow holes are provided vertically, it should be divided into six equal parts, and if four gas flow holes are provided vertically, it should be divided into eight equal parts, and so on, so that the center of the gas flow holes of each row is divided horizontally. This makes it easy to wire the heating wire to the insulator, facilitating the assembly of the heater. Furthermore, spaces can be provided between the unit divided insulators (or between the constituent divided insulators) positioned above and below, and the thickness of the insulator can also be made thinner.

[0121] By making the gas flow hole of the insulator vertically long and holding the heating wire with the front-to-back ridges on the ceiling and bottom, it is possible to create a large space above and below the outer surface of the heating wire, thereby maximizing the efficiency of heat exchange from the heating wire to the blown gas. The height or length of the front-to-back ridges is determined appropriately depending on the vertical length of the gas flow hole and the outer diameter of the heating wire to be wired, but these dimensions can also be set freely.

[0122] In the insulator of the present invention shown in Figures 1 to 3, the temperature sensor hole portion present in prototype 2 shown in Figure 5 is not shown, but it is of course possible to provide the temperature sensor hole portion present in prototype 2 in the unit split insulator of the present invention. This makes it possible to measure the temperature at a desired position on the heater during operation, and to appropriately control the temperature of the device. This temperature sensor insertion hole can be post-processed by laser processing, and as shown in Figure 4, a sensor insertion hole and a temperature measurement hole can be provided.

[0123] As described above, the present invention has provided a heater and insulator for generating hot air, which uses a set of insulators made by stacking unit divided insulators, and by improving the shape of the gas flow holes, maximizes the heat exchange efficiency between the blown gas from the heating wire and the insulator, and allows the heater capacity to be easily changed. [Explanation of symbols]

[0124] 10. Housing 15 Heating wire 20 Insulator 21 Unit division insulator 22 Segmented insulator 23 Anteroposterior protrusion 24 Vertical protrusion 25 Gas flow hole 26 Recess 27 Projection part 28 depression 50, 60 insulators 51 Recess 53 Projection part 54 Grooves 55, 65 Gas flow holes 56 Hole 58 Supply port 61 Unit division insulator 62 Segmented insulator 63, 64 Anteroposterior protrusion 66 Concave section 68 Recess 69, 70 gap 71 Sensor through hole 72 Temperature measurement hole

Claims

1. A heater for generating hot air has a plurality of insulators arranged in a housing, a spirally wound heating wire is inserted into a plurality of gas flow holes provided in the insulators, air is supplied from a supply port of the housing, and high-temperature hot air is discharged from a discharge port. The gas flow hole is formed so that its vertical length is greater than its horizontal length when viewed from the front, The upper and lower ceiling portions and the bottom portion of the gas flow hole are each formed with a longitudinal protrusion portion in the gas flow direction, One or more vertical protrusions are formed in the vertical direction on both the left and right side surfaces of the gas flow hole, This allows the front-rear protrusions provided on the ceiling and bottom surfaces to support the upper and lower edges of the heating wire, Furthermore, the vertical protrusions provided on both the left and right side surfaces are arranged between the pitches of the spirally wound heating wire, The heater for generating hot air is characterized in that the insulators are arranged approximately parallel to each other at predetermined intervals in the direction of gas flow.

2. The outer shape of the insulator as viewed from the front is generally rectangular, and the gas flow holes are generally rectangular and vertically elongated as viewed from the front, and a plurality of the gas flow holes are arranged vertically and horizontally as viewed from the front, In the single insulator, the central portions above and below the horizontally aligned gas flow holes are divided in the horizontal direction to form constituent divided insulators of approximately the same shape, and these constituent divided insulators are then stacked together to form the single insulator, Furthermore, the central portion of each of the constituent divided insulators is divided horizontally to form unit divided insulators, 2. A heater for generating hot air according to claim 1, wherein the single insulator is formed by stacking these unit divided insulators one on top of the other.

3. A heater for generating hot air as described in claim 2, characterized in that recesses are provided on the upper and lower surfaces of the constituent divided insulators of the insulator, and further, gaps are formed in the middle part excluding both end parts where the lower surface and upper surface of the constituent divided insulator are joined, and gaps are provided in the middle part excluding both end parts at the joint part between the unit divided insulators on the gas flow hole side.

4. 4. A heater for generating hot air according to claim 1, wherein the vertical length of the gas flow hole is between two and three times the outer diameter of the spirally wound heating wire.

5. 5. The heater for generating hot air according to claim 1, wherein the one insulator is arranged in parallel in the vertical direction and / or the horizontal direction, so that the heater capacity can be changed.

6. 6. The heater for generating hot air according to claim 1, wherein the intervals between the insulators arranged in the gas flow direction are set to become narrower toward the discharge port.

7. A heater for generating hot air as described in any one of claims 2 to 6, characterized in that a plurality of sensor insertion holes for inserting temperature sensors such as thermocouples are provided in the gas flow direction on the joining surface where the constituent divided insulators are joined.

8. An insulator used in a hot air generating heater has a plurality of insulators arranged in a housing, a spirally wound heating wire is inserted into a plurality of gas flow holes provided in these insulators, and air is supplied from a supply port of the housing and high-temperature hot air is discharged from a discharge port thereof, The shape of the gas flow hole of the insulator is formed so that the vertical length is longer than the horizontal length when viewed from the front, The upper and lower ceiling portions and the bottom portion of the gas flow hole are each formed with a longitudinal protrusion portion in the gas flow direction, One or more vertical protrusions are formed in the vertical direction on both the left and right side surfaces of the gas flow hole, This allows the front-rear protrusions provided on the ceiling and bottom surfaces to support the upper and lower edges of the heating wire, Furthermore, the vertical protrusions provided on both the left and right side surfaces are arranged between the pitches of the spirally wound heating wire, The outer shape of the insulator as viewed from the front is a substantially rectangular shape, and the gas flow holes are vertically elongated substantially rectangular shapes as viewed from the front, and a plurality of the gas flow holes are arranged vertically and horizontally as viewed from the front, In this single insulator, the central portions above and below the horizontally aligned gas flow holes are divided in the horizontal direction to form constituent divided insulators of approximately the same shape, and these constituent divided insulators are then stacked together to form the single insulator, Furthermore, the central portion of each of the constituent divided insulators is divided horizontally to form unit divided insulators, The insulator for a heater for generating hot air is characterized in that the single insulator is formed by stacking these unit divided insulators one on top of the other.

9. An insulator for a hot air generating heater as described in claim 8, characterized in that recesses are provided in the upper and lower surfaces of the constituent divided insulators of the insulator, and further, gaps are formed in the middle part excluding both end parts on the front and back sides where the lower and upper surfaces of the constituent divided insulators are joined, and gaps are provided in the middle part at the joint between the unit divided insulators excluding both end parts on the front and back sides.

10. 10. The insulator for a heater for generating hot air according to claim 8, wherein the vertical length of the gas flow hole is set to be between two and three times the outer diameter of the spirally wound heating wire.

11. An insulator for a heater for generating hot air as described in any one of claims 8 to 10, characterized in that a plurality of sensor insertion holes for inserting temperature sensors such as thermocouples are provided in the gas flow direction on the joining surface where the constituent divided insulators are joined.

12. 9. A divided insulator constituting the insulator of the heater for generating hot air according to claim 8.

13. 9. A unit divided insulator constituting the insulator of the hot air generating heater according to claim 8.

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