JP2013104628A - Ignition device of heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition device of a heater which suppresses an inrush current at fuel ignition small and has a simple structure for ease of maintenance.SOLUTION: A blast pipe 26 is provided which blows out air coming through an air inlet 22 toward a wood pellet W through a blow-out opening 24. In addition, it is provided with ceramic heaters 28, 30 in which a resistance value R of each built-in resistor 28a, 30a has a positive temperature coefficient. It is further provided with a control device 32 which controls a voltage application operation to the ceramic heaters 28, 30 from a power supply 62. The ceramic heaters 28 and 30 are arranged inside the blast pipe 26 in series to a flow of air passing therethrough, and the resistors 28a, 30a are individually connected to output of a power supply 62. The practical heating operations of the resistors 28a, 30a, which are performed by continuously applying a commercial voltage Vac to the ceramic heaters 28, 30, are started by the control device 32 with a predetermined time lag in a way that the ceramic heater 28 closer to the blow-out opening 24 is started first.

Description

  The present invention relates to an ignition device for a heater that ignites fuel such as wood pellets.

  Conventionally, this type of ignition device has been used in various types of heating appliances. For example, as disclosed in Patent Document 1, a combustion part that burns wood pellets as fuel, and a wood pellet in the combustion part There is a wood pellet combustion apparatus provided with a supply device for supplying air, a blower for sending air to the combustion section, an ignition device for igniting wood pellets in the fuel section, and a control circuit for controlling the operation of each section. This control circuit can be connected to a memory card, and changes settings such as the supply amount of wood pellets, the operating time of the ignition device, the rotation speed of the blower, etc. to the values recorded on the memory card inserted in the control circuit be able to. Further, a rod-shaped ceramic heater is exemplified as the heating element of the ignition device, and the heated ceramic heater is ignited by contacting with the wood pellet.

  Further, as disclosed in Patent Document 2, an ignition device that radiates heat from the surface of a ceramic body to ignite the fuel gas of the heater by radiating the heat of the resistance heater built in the ceramic heater, and the resistance value of the heater resistor There is an ignition device for a heater provided with a control device that detects the above and interrupts energization of the heater resistor. This control device detects the temperature of the heater resistor by detecting the resistance value of the heater resistor, stops energization when the temperature reaches the upper limit reference value, and resumes energization when the temperature falls to the lower limit reference value. repeat. By this operation, extreme heating of the heater resistor due to the heat transfer delay from the heater resistor to the ceramic resistor is prevented.

JP 2009-24983 A JP-A-5-248636

  Since the ignition device of the wood pellet combustion apparatus disclosed in Patent Document 1 has a structure in which a high-temperature ceramic heater exceeding 700 ° C. is in contact with the wood pellet, the residue of the burned wood pellet adheres to the ceramic heater surface. It was easy to get dirty, and maintenance such as cleaning was troublesome.

  In addition, any of the ignition devices disclosed in Patent Documents 1 and 2 has a problem that a very large inrush current flows when a ceramic heater is energized to generate heat for ignition. This type of ceramic heater can generate heat using a circuit as shown in FIG. That is, the output of the power supply 10 is connected to the resistor 12a of the ceramic heater 12 through the switch 14a of the control device 14, and the control device 14 turns on the switch 14a to apply the voltage Vac. The voltage Vac is a commercial voltage of AC100V that is taken out from a general household outlet.

  As shown in FIG. 11B, the ceramic heater 12 has a positive temperature coefficient of the resistance value R of the resistor 12a, and the resistance value R is smaller as the temperature of the ceramic heater 12 is lower. Therefore, when the switch 14a is turned on while the ceramic heater 12 is cooled, as shown in FIG. 11B, the effective current Ir has a peak immediately after being turned on, and a large inrush current Irp (0) is generated. Thereafter, the resistance value R gradually increases with the heat generation of the resistor 12a, the effective current Ir decreases, the temperature eventually saturates to a predetermined value, the effective current Ir converges to the stable current Ir (0), and the resistor 12a continues to generate heat with stable power P (0). In the case of the ignition device of Patent Document 2, in addition to the above-described operation, the switch 14a is turned off at a predetermined timing, and thereafter the operation is repeatedly turned on and off. This is because the inrush current Irp (0) is It is after it has occurred.

  When such a large inrush current Irp (0) flows, every time the heater is lit, the switchboard breaker shuts off due to excess capacity, or the commercial power line's AC100V temporarily drops, causing various electronic devices in the home. The device might malfunction.

  The present invention has been made in view of the above-described background art, and provides an ignition device for a heating appliance that can suppress an inrush current when igniting a fuel to a small size and has a simple structure and easy maintenance. Objective.

  The present invention provides a blower pipe that blows air flowing in from a wind inlet toward a fuel from a blower outlet, a plurality of ceramic heaters having a positive temperature coefficient of resistance value of a built-in resistor, and a power supply to the ceramic heater. A plurality of ceramic heaters arranged in series with respect to the flow of air passing through the inside of the blower pipe, and each of the resistors. Heating that is individually connected to the output of the power source, and that starts the main heating operation of the resistor with a predetermined time difference by continuously applying the output voltage of the power source to each ceramic heater. It is an ignition device for an appliance.

  The fuel is wood pellets, and the wood pellets are ignited by heated air blown out from the outlet of the blower pipe. Furthermore, the control device may perform the main heat generation operation in order from the ceramic heater closer to the blower outlet of the blower pipe.

  The control device intermittently applies the output voltage of the power source at a predetermined time ratio to the ceramic heater that is on standby before the start of the main heating operation, and causes the resistor of the ceramic heater to perform a preliminary heating operation. Also good. The ceramic heater may be installed inside a separate tubular member, and the blower tube may be formed by bending a plurality of the tubular members at a predetermined angle and connecting them in series.

  The ignition device for a heating appliance according to the present invention suppresses the inrush current by shifting the timing for continuously applying the power supply voltage to each ceramic heater, that is, the timing for starting the main heating operation when the fuel is ignited. Can be reduced.

  In addition, by starting the main heating operation in order from the ceramic heater closer to the outlet from which the heated air is blown, the temperature of the heated air can be increased efficiently, and the fuel is ignited and ignited in a short time. be able to. In addition, the power supply voltage is intermittently applied at a predetermined time ratio to the standby ceramic heater before the main heating operation to perform a preliminary heating operation, thereby reducing the temperature of the heating air more efficiently and in a shorter time. Can be raised.

  In addition, if a plurality of tubular members provided with ceramic heaters are prepared and the blower tube is formed by connecting the tubular members at an appropriate angle, the ignition device is arranged even in a narrow and complicated space inside the heater. This can contribute to the downsizing of the heater.

It is the front view (a) and left view (b) which show one Embodiment of the ignition device of the heating appliance of this invention. It is AA sectional drawing (a) of FIG. 1, and BB sectional drawing (b). It is the front view (a) and right view (b) which show the heating appliance which provided the ignition device of this embodiment inside. It is a schematic diagram explaining the structure of the part concerned in the ignition of the fuel inside the heating appliance of FIG. It is the circuit diagram (a) explaining the operation | movement of the control apparatus of the ignition device of this embodiment, and a time chart (b). It is a graph which shows the resistance value-temperature characteristic of the ceramic heater used for this embodiment. It is a time chart explaining operation | movement of the control apparatus of a modification. It is an actual measurement waveform which shows the operation example of the ignition device of the prototype heating appliance. It is an actual measurement waveform which shows the other operation example of the ignition device of the prototype of the heating appliance made as an experiment. It is an actual measurement waveform which shows the operation example of the ignition device of the heating appliance similar to the past. It is the circuit diagram (a) explaining the operation | movement of the control circuit of the conventional ignition device, and a time chart (b). It is a graph which shows the resistance value-temperature characteristic of a ceramic heater.

  Hereinafter, an embodiment of an ignition device for a heating appliance according to the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the ignition device 20 according to this embodiment is installed inside a blower pipe 26 that blows air flowing in from the air inlet 22 toward the fuel from the blowout opening 24, and the blower pipe 26. , Two ceramic heaters 28 and 30 for heating the passing air, and a control device 32 for controlling heat generation of the ceramic heaters 28 and 30.

  The ceramic heaters 28 and 30 are the same element, and include resistors 28a and 28b in an elongated cylindrical ceramic body, and lead wires 34 for supplying power to the resistors 28a and 30a at the base portion of the ceramic body. 36 is connected. As shown in FIG. 3, the resistors 28 a and 28 b have a positive temperature coefficient and a resistance value R (which is larger than the resistor 12 a of the ceramic heater 12 described in the description of the background art above. Here, the resistance value is approximately twice as high.

  The air duct 26 is composed of two tubular members 38 and 40. The tubular member 38 is provided with a blower outlet 24 at a tip end portion of a cylindrical outer shape, a ceramic heater 28 is disposed inside, and a root portion thereof is fixed to a rear end portion of the tubular member 38. The lead wire 34 of the ceramic heater 28 is drawn out from the rear end portion of the tubular member 38. Further, on the side surface of the tubular member 38, a pair of left and right attaching portions 38a used for attaching to the heating appliance is erected.

  The tubular member 40 has a cylindrical outer end closed, a ceramic heater 30 disposed inside, and a root portion fixed to the rear end of the tubular member 40. The lead wire 36 of the ceramic heater 30 is drawn out from the rear end portion of the tubular member 40. Further, the wind inlet 22 opens at a position near the rear end of the side surface of the tubular member 38.

  The tubular members 38, 40 are integrally connected to a position near the rear end of the side surface of the tubular member 38 and a position near the front end of the side surface of the tubular member 40 by welding or the like, and the inner space continues through the communication hole 42. ing. Here, in accordance with the internal structure of the heating appliance to which the ignition device 20 is attached, the tubular members 38 and 40 are connected so as to intersect at a predetermined angle (here, intersect at right angles), and the integral air duct 26 is formed. Is formed.

  In the ignition device 20 having the above-described configuration, air flows from the air inlet 22 of the blower pipe 26 and the heated air heated by the ceramic heaters 28 and 30 can be blown out from the air outlet 24. The configuration and function of the control device 32 will be described in the following operation description.

  Next, the configuration of the heating device 44 on which the ignition device 20 is mounted will be described, and the operation of igniting the fuel of the heating device 44 using the ignition device 20 will be described. The heating device 44 is a stove for indoor heating using wood pellets W as fuel. The wood pellet W is a solid fuel obtained by crushing timber such as thinned wood and sawn timber and compressing it into a pellet, and has recently attracted attention as a new renewable and environmentally friendly fuel. There are a plurality of types of wood pellets. Generally, when heated to 200 to 400 ° C., decomposition of the combustion gas starts in the pellets, and ignition continues when the state continues for a long time. Further, when heated to 400 ° C. or higher, it ignites in a short time.

  As shown in FIG. 4, the heating device 44 has a substantially rectangular casing 46, a hot air outlet 48 is provided at the upper front portion of the casing 46, and a duct 48 for exhausting smoke to the outside at the lower rear portion. The supply port 50 of the wood pellet W is provided in the upper surface. In addition, an AC cable (not shown) is connected to an outlet in order to supply power to the electronic devices inside the heating appliance 44.

  As shown in the schematic diagram of FIG. 5, the portion of the heating device 44 that combusts fuel and generates thermal energy includes a pellet tank 52, a combustion chamber 54, a fan 56, and an ignition device 20. In the pellet tank 52, the wood pellets W are supplied from the upper supply port 50, and the wood pellets W are quantitatively discharged from the discharge nozzle 52a at the lower end portion.

  The combustion chamber 54 is a space for burning the wood pellets W. A combustion pot 58 for receiving the wood pellets W quantitatively discharged from the discharge nozzle 52a below, and a heat energy generated by burning the wood pellets W are absorbed. A heat exchanger (not shown) is provided. The ignition device 20 is attached so that a portion of the tubular member 38 near the outlet 24 is inserted into the combustion chamber 54, and the tubular member 40 and the air inlet 22 are located outside the combustion chamber 54. Heated air taken in from the air inlet 22 and blown out from the air outlet 24 is directly blown to the wood pellets W in the combustion pot 58.

  The fan 56 is driven in a direction to decompress the air in the combustion chamber 54 through the exhaust passage 60. Therefore, by driving the fan 56, an air flow as shown by a broken line in FIG. 5 is generated inside the housing 46, and oxygen necessary for the combustion of the wood pellets W is taken into the combustion chamber 54 and is generated by the combustion. The air that has received the heat energy is transferred to the heat exchanger. Then, the heat-exchanged air is discharged outdoors. Similarly, an air flow in which normal temperature air flows into the wind inlet 22 of the ignition device 20 and heated air is blown out from the outlet 24 is also generated.

  The voltage application operation to the ceramic heaters 28 and 30 of the ignition device 20 is controlled by a control circuit 32 having two switches 64 and 66 as shown in the circuit diagram of FIG. A power supply 62 that outputs the commercial voltage Vac is connected to the control circuit 32 through an outlet (not shown), and is individually connected to the resistors 28a and 30a through the switches 64 and 66. The switches 64 and 66 are preferably semiconductor switching elements capable of conducting in both directions, such as triacs. The control circuit 32 maintains the ON state of the switch 64 when the ceramic heater 28 is caused to generate heat, and continuously applies the voltage Vac to the resistor 28a. Similarly, when the ceramic heater 30 generates heat, the switch 66 is kept on and the voltage Vac is continuously applied to the resistor 30a. Further, when the ceramic heater 30 is preheated, the switch 66 is turned on / off at a predetermined cycle and time ratio, and the voltage Vac is intermittently applied to the resistor 30a.

  Next, the operation | movement at the time of igniting the wood pellet W using the ignition device 20 is demonstrated based on the time chart of FIG.6 (b). First, the control device 32 of the ignition device 20 turns on the switch 64 by the operation of the user, and the voltage Vac is continuously applied to the resistor 28a, thereby causing the ceramic heater 28 closer to the outlet 24 to generate heat. Immediately after the switch 64 is turned on, since the temperature of the resistor 28a is cooled, the resistance value R is small, and the current Ir28 increases transiently in the resistor 28a. Here, as shown in FIG. 3, the resistance value R of the resistor 28a of the ceramic heater 28 has a value about twice that of the resistor 12a of the ceramic heater 12 of FIGS. 11 and 12 described in the background art. Therefore, the peak of the effective current Ir28 is about 1/2 times the effective current Irp (0) of FIG.

  Further, almost simultaneously with the turning on of the switch 64, the control device 32 starts the on / off operation of the switch 66, and intermittently applies the voltage Vac to the resistor 30a to preheat the other ceramic heater 30. . In order to suppress the preliminary heat generation to a heat generation amount smaller than the main heat generation of the ceramic heater 28, the on-time ratio of the switch 64 may be set to about 20 to 40%. Switch on and off in units of one cycle of commercial frequency (50 or 60 Hz), and turn on three cycles out of ten cycles. Immediately after the on / off of the switch 64 is started, the resistance value R of the resistor 30a is small, but the peak of the effective current Ir30 is about 1/3 times the effective current Ir28 (about 1 / the effective current Irp (0)). 6 times). As a result, the first inrush current Irp (11), which is the peak of the effective current Ir output from the power supply 62, is about 2/3 times the inrush current Irp (0).

  Thereafter, the temperature of the resistor 28a of the ceramic heater 28 that generates heat increases, the resistance value R increases, and the effective current Ir decreases. Then, at the timing when the effective current Ir becomes about half of the first inrush current Irp (11), the control device 32 stops the on / off operation of the switch 66 and keeps it on. Then, the voltage Vac is continuously applied to the resistor 30a to cause the ceramic heater 30 to generate heat. Immediately after the switch 66 turns on, the effective current Ir30 flowing through the resistor 30a increases about three times. As a result, the effective current Ir output from the power source 62 increases correspondingly, and a second inrush current Irp (12) is generated. However, since the resistance value R of the resistor 30a is increased to some extent by the preheating, the second inrush current Irp (12) is smaller than the first inrush current Irp (0).

  When this state continues, the temperature of the resistors 28a and 30a eventually saturates to a predetermined value, the effective currents Irp28 and Irp30 also converge, the total current Ir converges to the stable current Ir (0), and the resistor 28a , 30a continues to generate heat with stable power P (0). Stable power P (0) shown in FIG. 6 is equivalent to stable power P (0) in FIG.

  The ignition device 20 generates heat from the ceramic heaters 28 and 30 as described above, heats the room temperature air taken into the blower pipe 26, and blows the heated air from the outlet 24. The heated air may be raised to 260 ° C. when the second inrush current Irp (12) flows through the ceramic heaters 28 and 30 and then raised to 450 to 500 ° C. Then, the wood pellet W starts to decompose when the temperature of the heated air exceeds 260 ° C., and ignites until it reaches 450 ° C.

  As described above, when the ignition device 20 ignites the wood pellet W, the igniting current is changed by shifting the timing at which the voltage Vac is continuously applied to the ceramic heaters 28 and 30, that is, the timing at which the main heating operation is started. The peak can be kept small by dispersing in Irp (11) and Irp (12). Accordingly, the burden on the power source 62 is reduced, and the inconvenience that the breaker of the switchboard falls every time the heating device 44 is ignited is less likely to occur.

  In addition, since the main heating operation is started in order from the ceramic heater 28 closer to the outlet 24 from which the heated air is blown out, the temperature of the heated air rises quickly. Assuming that the main heating operation is performed from the ceramic heater 30 away from the outlet 24, the heated air that has received heat generated by the resistor 30 a is deprived of heat when passing through the cooled tubular member 38, When it blows out from the exit 24, temperature will fall. Therefore, by performing the main heating operation from the ceramic heater 28 as described above, the temperature of the heated air can be increased efficiently, and the time for ignition and ignition of the fuel can be shortened.

  Furthermore, the preliminary heating operation is performed by intermittently applying the commercial voltage Vac at a predetermined time ratio to the ceramic heater 30 waiting before the main heating operation, thereby further improving the temperature of the heated air while suppressing the inrush current. It can be raised in a short time.

  Moreover, since the tubular members 38 and 36 provided with the ceramic heaters 28 and 30 can be connected to an appropriate angle within a range that does not disturb the air flow, the blower pipe 26 can be formed. Even in an intricate space, the ignition device 20 can be arranged, which can contribute to the downsizing of the heating appliance 44.

  In addition, the ignition device of the heating appliance of this invention is not limited to the said embodiment. For example, the operation of the ignition device 20 described with reference to FIG. 6A is changed, the ceramic heater 30 does not perform the preheating operation, and the switch 66 is held in the off state during standby before starting the main heat generation operation. You may change so that it does. In this way, although the rise in the temperature of the heated air is slightly delayed by the amount of heating due to the preliminary heat generation operation, it is not necessary to turn on and off the switches 64 and 66 at high speed. It is possible to use a mechanical relay that is simplified and easy to handle. However, as shown in FIG. 7, the first inrush current decreases from Irp (11) to Irp (21) and the second inrush current increases from Irp (12) to Irp (22). In order to keep the inrush current Irp (22) at a certain level or less, it is necessary to prevent the switch 66 from turning on too early.

  The ceramic heater can be selected from a cylindrical type, a strip type, and other various commercially available shapes in place of the cylindrical type like the ceramic heaters 28 and 30 in FIG. . In that case, it is preferable to change the shape of the inner wall of the transfer pipe according to the shape of the ceramic heater so that the heat generated by the ceramic heater is efficiently transmitted to the air.

  Further, a high-power ignition device in which three or more ceramic heaters are combined may be configured. Even in this case, the heating air is started by starting the main heating operation in order from the ceramic heater closest to the air outlet. The temperature of the can be increased efficiently.

  The fuel to be ignited is not limited to wood pellets, and may be solid fuel, liquid fuel, or gaseous fuel other than wood pellets. Therefore, the ignition device of the present invention can be mounted on various heating appliances.

  An example of the ignition device 20 according to the above-described embodiment will be described. The ceramic heaters 28 and 30 are the same, and the resistance value R is selected such that the commercial voltage Vac is 100 V and the stable power P (0) is about 600 W in total. Then, the prototype ignition device 20 was mounted on an actual heating appliance 44 to perform an ignition test, and the currents Ir28, Ir30, Ir flowing through the ceramic heaters 28, 30 and the temperature Tk of the heated air blown from the outlet 24 were measured. The heating appliance 44 is a general household stove, and is required to start warming the room as quickly as possible after the user performs an ignition operation. Therefore, in the heating appliance 44, the time from the ignition operation until the wood pellet W is ignited is set to a maximum of 120 seconds or less.

  The graph of FIG. 8 is data when the ceramic heater 28 performs the main heat generation operation from the beginning, and the ceramic heater 30 performs the main heat generation operation about 14 seconds after the preliminary heat generation operation is performed first. The preliminary heating operation of the ceramic heater 30 switches on / off of the switch 66 every cycle of the commercial frequency (50 or 60 Hz), and turns on three cycles of the 10 cycles, thereby changing the on-time ratio to 30%. I made it. Specifically, it was set to repeat the operation of turning on 7 times and turning off 3 times in 10 cycles. Further, after 300 seconds passed from the ignition operation, both the switches 64 and 66 of the control circuit 32 were turned off, and the power supply to the ceramic heaters 28 and 30 was stopped.

  As a result of the test, as shown in FIG. 8, the time for the heated air Tk to reach 260 ° C. was 45 seconds, and after 300 seconds, it increased to 455 ° C. Therefore, the target of igniting the wood pellet W within 120 seconds can be sufficiently realized. Also, the first inrush current Irp (11) was 13A, and the second inrush current Irp (12) was 8A.

  Further, the graph of FIG. 9 shows that the ceramic heater 28 performs the main heating operation from the beginning, and the ceramic heater 30 holds the switch 66 off without performing the preliminary heating operation first, and after about 14 seconds, the main heating operation is performed. This is the data when In this case, the time for the heated air Tk to reach 260 ° C. was 50 seconds, and increased to 445 ° C. after 300 seconds. Accordingly, as shown in FIG. 8, the time until the wood pellet W is ignited is about 10 seconds longer than when preliminary heating is performed, but it is possible to ignite within 120 seconds. In addition, the first inrush current Irp (21) was 10A, and the second inrush current Irp (22) was 13A, and the peak of the inrush current could be kept small.

  On the other hand, the comparison data graph of FIG. 10 is data when the ceramic heaters 28 and 30 both perform the main heating operation from the beginning, and the inrush current Irp (0) is as large as 20A. Therefore, by using the ignition device 20 according to this embodiment, an effect of reducing the peak of the inrush current to about 2/3 times the value was obtained.

20 Ignition device 22 Air inlet 24 Air outlet 26 Blower pipes 28, 30 Ceramic heaters 28a, 30a Resistor 32 Controllers 38, 40 Tubular member 42 Communication hole 44 Heating device W Wood pellet

Claims (5)

A blower pipe that blows out the air flowing in from the air inlet toward the fuel from the air outlet;
A plurality of ceramic heaters having a positive temperature coefficient of resistance of a built-in resistor;
A controller for controlling a voltage application operation to the ceramic heater by a power source,
A plurality of the ceramic heaters are arranged in series with respect to the flow of air passing through the inside of the air blowing pipe inside the air blowing pipe, and individually connected to the output of the power source for each resistor.
The stove igniter characterized in that the control device starts the main heating operation of the resistor, which is performed by continuously applying the output voltage of the power source to each ceramic heater with a predetermined time difference.   The stove igniter according to claim 1, wherein the fuel is wood pellets, and the wood pellets are ignited by heated air blown from the blower outlet of the blower pipe.   The stove ignition device according to claim 2, wherein the control device causes the main heating operation to be performed in order from the ceramic heater closer to the air outlet of the blower pipe.   The control device intermittently applies the output voltage of the power source at a predetermined time ratio to the ceramic heater that is on standby before the start of the main heating operation, and causes the resistor of the ceramic heater to perform a preliminary heating operation. Item 4. The stove ignition device according to Item 2 or 3. The stove ignition according to claim 4, wherein the ceramic heater is installed inside a separate tubular member, and the blower tube is formed by bending a plurality of the tubular members at a predetermined angle and connecting them in series. apparatus.

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