JP2663388B2 - Hot air heater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hot air heater capable of switching a combustion state of a burner to a plurality of stages.

[Related Art] Conventionally, a hot air heater capable of switching a combustion state of a burner between a strong combustion state and a weak combustion state, for example, an FF type oil hot air heater has been proposed. In this oil hot air heater, an overheat safety device such as a temperature fuse or a thermistor for stopping the combustion of the burner when the temperature inside the device rises above a predetermined value is provided. Further, in the oil warm air heater, when the combustion state of the burner is switched from the strong combustion state to the weak combustion state, the amount of air blown by the convection fan is switched from strong to weak.

[Problems to be Solved by the Invention] However, in the conventional oil warm air heater, when the burner is operated for a long time in a strong combustion state, the temperature inside the machine is considerably increased and stabilized. In such a case, if the air flow of the convection fan is synchronized with the combustion state and the air flow is immediately switched from the strong air flow to the weak air flow, not only does the rising internal temperature not decrease rapidly, but the internal temperature further increases temporarily. . Therefore,
There is a possibility that electric devices such as a control circuit and an overheat safety device arranged in the machine may malfunction.

In order to solve this problem, when the combustion state of the burner is switched from the strong combustion state (strong combustion amount) to the weak combustion state (weak combustion amount), the electric device does not malfunction due to the air flow of the convection fan. A temperature heater that delays a certain amount of time to a safe range and then switches from a strong airflow to a weak airflow can be considered.

However, when the combustion state of the burner is a weak combustion state,
From the viewpoint of the heating feeling, the convection fan is desirably a weak air flow, and it is not preferable to maintain the convection fan air flow at a strong air flow continuously for the above-described predetermined time because cool air may be blown out. .

According to the present invention, when the combustion state of the burner is switched from the strong combustion state to the weak combustion state, as the combustion state of the burner decreases stepwise, the stepwise decrease in the amount of air blown by the convection blower is made slower. Another object of the present invention is to provide a warm air heater capable of preventing malfunctions of a control circuit, an electric device, and the like disposed in the machine without obstructing a heating feeling such as blowing of cold air.

[Means for Solving the Problems] The invention according to claim 1 includes a hot air duct for sending air toward a room, and a convection blower for generating an airflow toward the room in the hot air duct. A burner that burns fuel to heat air passing through the warm air duct, a heat exchanger that heats air passing through the warm air duct by exchanging heat with the combustion heat of the burner, Temperature detection means for detecting the temperature of the burner, temperature setting means for setting a target indoor temperature, and the burner in accordance with the detected temperature detected by the temperature detection means and the target temperature set by the temperature setting means. Combustion control means for controlling the combustion state of
A blower control unit that controls a blown amount of the convection blower according to a combustion state of the burner, wherein the combustion control unit changes the combustion state of the burner from a strong combustion state to a weak combustion state. When the combustion state of the burner is switched to, the combustion state of the burner is decreased stepwise every time the first holding time elapses from the strong combustion state to the weak combustion state, and the blower control means determines that the combustion state of the burner is stepwise. As the air flow decreases, the air flow rate of the convection blower is gradually decreased from a strong air flow to a weak air flow every time a second holding time longer than the first holding time elapses. As the air flow gradually decreases, a technical means was adopted in which the gradual decrease in the amount of air blown by the convection blower was made slower.

[Operation] According to the invention described in claim 1, when the combustion state of the burner is switched from the strong combustion state to the weak combustion state, the combustion state of the burner is changed from the strong combustion state to the weak combustion state for the first holding time. It decreases step by step as time passes. Further, as the combustion state of the burner decreases stepwise, the amount of air blown by the convection blower decreases stepwise every time a second holding time longer than the first holding time elapses from a strong airflow to a weak airflow. Accordingly, as the combustion state of the burner decreases stepwise, the stepwise decrease in the amount of air blown by the convection blower becomes slower.

Therefore, when the combustion state of the burner is switched from the strong combustion state to the weak combustion state, as the combustion state of the burner decreases stepwise, the amount of air blown by the convection blower gradually decreases gradually from the strong airflow to the weak airflow. By doing so, the internal temperature of the hot air heater, particularly the temperature of the heat exchanger, is gradually reduced to an optimum temperature according to the combustion state of the burner.

[Effect of the Invention] The invention according to claim 1 is that the convection air blower is not maintained at the strong air flow for a long time until the air flow is switched from the strong air flow to the weak air flow. By avoiding blowing cold air toward the air, heating feeling such as blowing cold air is not hindered. Further, when the combustion state of the burner is switched from the strong combustion state to the weak combustion state, the convection blower does not immediately switch from the strong air flow to the weak air flow, so that the temperature inside the hot air heater is not exposed to a high temperature. This can reliably prevent malfunctions of electrical devices such as a control circuit and an overheat safety device disposed inside the hot air heater. Furthermore, when the combustion state of the burner decreases stepwise, the air volume of the convection air blower decreases with a delay toward the weak air flow side, so the temperature inside the hot air heater, especially the temperature of the heat exchanger, is reduced by the cold air flow. And the internal temperature can be gradually reduced without causing the inside temperature to rise.

[Embodiment] A hot air heater according to the present invention will be described with reference to an embodiment shown in Figs.

 FIG. 1 shows a schematic structure of an FF type gas hot air heater.

The FF gas hot air heater 1 corresponds to the hot air heater of the present invention, and includes a hot air duct 2, a convection fan 3, a combustion duct 4, a combustion fan 5, a gas burner 6, a heat exchanger 61. ,
A combustion case 62 and the microcomputer 10 are provided.

The hot air duct 2 draws indoor air from the inlet 21,
A warm air passage for blowing warm air from the outlet 22 toward the room is formed. The thermistor 11 is attached to the suction port 21. The convection blower 3, the gas burner 6, the heat exchanger 61, the combustion case 62, and the overheat safety device 17 are provided inside the hot air duct 2.

The convection blower 3 includes an electric motor 31 whose rotation speed changes in accordance with the amount of electricity, and a convection fan 32 driven to rotate by the current motor 31 to generate an airflow in the warm air duct 2 toward the room.

The combustion duct 4 forms an air passage for supplying the outdoor air sucked from outside and the fuel gas introduced from the fuel gas supply means 7 to the gas burner 6.

The combustion blower 5 has an electric motor 51 whose rotation speed changes in accordance with the amount of electric power, and a combustion fan 52 which is driven to rotate by the electric motor 51 and generates an airflow in the combustion duct 4 toward the outside of the room.

The gas burner 6 is a part corresponding to the burner of the present invention,
It has a combustion plate 64.

The heat exchanger 61 has one end connected to the combustion case 62 and exchanges heat between the air passing through the hot air duct 2 and the internal combustion heat. The other end of the heat exchanger 61 is connected to an exhaust duct 63. The combustion case 62 is located downstream of the combustion plate 64,
A thermocouple 12 and a spark electrode 13 are provided. The exhaust duct 63 forms an air passage for discharging the combustion exhaust gas of the air-fuel mixture to the outside of the room.

The fuel gas supply means 7 has a first main solenoid valve 71, a second main solenoid valve 72, a flow control orifice 73, a proportional control valve 74, and a gas pipe 75 in which these are disposed.

The first main solenoid valve 71 and the second main solenoid valve 72 are opened when energized, and closed when energization is stopped. Orifice 73
Is arranged in parallel with the proportional control valve 74 to adjust the supply amount of fuel gas (hereinafter referred to as gas amount). The proportional control valve 74 is
This is a valve that adjusts the amount of fuel gas by changing the degree of opening of the gas pipe 75 in accordance with the amount of energization, thereby changing the supply pressure of the fuel gas.

The microcomputer 10 is a combustion control unit of the present invention,
A component corresponding to a blower control means, which controls the set temperature display 16 by inputting signals from the thermistor 11, the thermocouple 12, the spark electrode 13, the operation switch 14, and the temperature adjustment button 15. The thermistor 11 is installed near the inlet 21 of the hot air duct 2 of the FF-type gas hot air heater 1 and is a temperature detecting means for detecting the temperature of indoor air (hereinafter referred to as room temperature) drawn from the inlet 21. . The temperature adjustment button 15 is a setter (temperature setting means) for setting a target indoor temperature (hereinafter, referred to as a set temperature). The set temperature display 16 displays the set temperature set by the temperature adjustment button 15. Overheat safety device 17
Is a temperature fuse, a thermistor, or the like disposed inside the FF type gas hot air heater 1 and sends a signal to the microcomputer 10 so as to stop the heating operation when the temperature inside the machine rises above a predetermined value. send.

The microcomputer 10 includes these thermistors 11,
Thermocouple 12, operation switch 14, temperature control button 15
And the electric signal sent from the overheat safety device 17, the spark electrode 13, the electric motors 31, 51, the first main solenoid valve.
71, second main solenoid valve 72, proportional control valve 74 and set temperature display
Control 16

During the steady-state combustion control, the microcomputer 10 gradually changes the combustion state of the gas burner 6 from the weak combustion state (weak combustion amount) to the strong combustion state (strong combustion amount) in eight stages corresponding to the room temperature and the set temperature. (Combustion amount). That is, the microcomputer 10
Changes the amount of electricity supplied to the electric motor 51 and the proportional control valve 74 to the gas burner 6 in eight stages from a weak combustion state to a strong combustion state in accordance with the room temperature and the set temperature.

When the microcomputer 10 switches the combustion state of the gas burner 6 from the weak combustion state to the strong combustion state,
Depending on the rate of change of the gas amount (the amount of electricity to the proportional control valve 74), the air flow of the convection fan 32 (the amount of electricity to the electric motor 31)
At a predetermined change rate. In this case, a convection fan
The holding time of each of the 32 air flow rates for each air flow level is 1
The retention time is set to be almost the same for each stage.

When switching the combustion state of the gas burner 6 from the strong combustion state to the weak combustion state, the microcomputer 10 responds to the change rate of the gas amount (the amount of electricity supplied to the proportional control valve 74) according to the changing speed.
The amount of air blown by the convection fan 32 (the amount of power supplied to the electric motor 31) is changed at the second change speed. In this case, the second holding time (for example, 5 seconds) for each air volume stage of the air volume of the convection fan 32
Is set to be longer by a predetermined time (for example, 3 seconds) than the first holding time (for example, 2 seconds) for each stage of the gas amount (see the graph of FIG. 2).

Here, in the graph of FIG. 2, the solid line indicates the gas amount to the gas burner 6 that changes every first holding time (for example, 2 seconds) when the combustion state of the gas burner 6 switches from the strong combustion state to the weak combustion state. The dashed line indicates how the air flow of the convection fan 32 changes according to the decrease in the gas amount. As can be seen from FIG. 2, the amount of air blown by the convection fan 32 increases for a first holding time (for example, 2 seconds) as the combustion state of the gas burner 6 gradually decreases from the strong combustion state to the weak combustion state. Each time a longer second holding time (for example, 5 seconds) elapses, the amount of air gradually decreases from the strong airflow to the weak airflow. As a result, as the combustion state of the gas burner 6 decreases stepwise, the amount of air blown by the convection fan 32 decreases gradually on the weak airflow side than on the strong airflow side in the stepwise decrease in the airflow of the convection fan 32. (Delay time is lengthened).

FIG. 3 is a flowchart showing the main control of the microcomputer 10.

First, a room temperature is detected (step S1), a set temperature is read (step S2), and a target range (for example, a set temperature ± 2 ° C.) is calculated from the set temperature (step S3). Then, it is determined whether the room temperature is higher than the target range (step
S4). When the room temperature is greater than the target range (Yes), the weak combustion control subroutine shown in FIG. 4 is performed (step S5), and the control in step S1 is performed.

In step S4, room temperature is not in the target range (No)
At this time, it is determined whether or not the room temperature is lower than the target range (step S6). When the room temperature is smaller than the target range (Yes), a strong combustion control subroutine is performed (step S7).
Control S1.

In step S6, room temperature is not in the target range (No)
At this time, a steady combustion control subroutine is performed (step S8),
Control of step S1 is performed.

During steady-state combustion, switching is performed in six stages between the strong combustion state and the weak combustion state according to the difference between the room temperature and the set temperature.

FIG. 4 shows a subroutine representing weak combustion control of the microcomputer 10.

In step S4, room temperature> target range (Yes)
At this time, it is determined whether the combustion state of the gas burner 6 is a weak combustion state. That is, it is determined whether or not the minimum energization amount is supplied to the proportional control valve 74 (step S21). When the combustion state of the gas burner 6 is a weak combustion state (Yes), the control in step S25 is performed.

In step S21, when the combustion state of the gas burner 6 is not a weak combustion state (No), the amount of electricity supplied to the electric motor 51 is reduced by one step (−1) (step S22).
The amount of electricity supplied to the proportional control valve 74 is reduced by one step (-
1) is performed (step S23). Subsequently, it is determined whether a first holding time (for example, 2 seconds) has elapsed (step S24). Step 1 when the first retention time has elapsed (Yes)
The control of S21 is performed.

In step S24, when the first holding time has not elapsed (No), it is determined whether or not the air volume of the convection fan 32 is a weak air volume. That is, it is determined whether the minimum energization amount is supplied to the electric motor 31 (step S25). Electric motor 3
When the minimum energization amount is supplied to 1 (Yes), the subroutine ends.

In step S25, when the minimum energization amount is not supplied to the electric motor 31 (No), it is determined whether a second holding time (for example, 5 seconds) has elapsed (step S26). When the second holding time has not elapsed (No), the control in step S24 is performed.

In step S26, the second holding time has elapsed (Ye
At s), the amount of current supplied to the electric motor 31 is reduced by one step (−1) (step S27). Then step S24
Control.

The operation of the FF gas hot air heater 1 of the present embodiment will be described with reference to FIGS.

When the operation switch 14 is set to the “on” side, the FF-type gas warm air heater 1 is forcibly and strongly operated until a predetermined time has elapsed. After the forced “strong” operation, the combustion state of the gas burner 6 is controlled according to the temperature difference between the room temperature detected by the thermistor 11 by the microcomputer 10 and the set temperature set by the temperature adjustment button 15.

For example, when switching the combustion state of the gas burner 6 from the strong combustion state to the weak combustion state, the amount of electricity supplied to the electric motor 51 and the proportional control valve 74 of the combustion blower 5 is reduced to the seventh stage. The amount of power supplied to the electric motor 51 and the proportional control valve 74 each time the first holding time (for example, 2 seconds) elapses until the amount of power supplied to the electric motor 51 and the proportional control valve 74 becomes the minimum amount of power supply. Is gradually reduced. That is, the amount of current supplied to the electric motor 51 and the proportional control valve 74 gradually decreases every time the first holding time (for example, 2 seconds) elapses from the maximum amount of current to the minimum amount of current (second time). (See graph in FIG. 2).

Therefore, as the rotational speed of the combustion fan 52 decreases stepwise, the air flow rate of the combustion fan 52 switches from the strong air flow to the weak air flow through six air flow stages.
Therefore, the amount of outdoor air (combustion air) supplied to the gas burner 6 decreases.

Further, the proportional control valve 74 corresponds to the reduced amount of air.
By reducing the degree of opening of the gas pipe 75,
The amount of fuel gas supplied to the gas burner 6 also decreases. For this reason, even when the combustion state of the gas burner 6 is switched from the strong combustion state to the weak combustion state, an air-fuel mixture having an optimal air-fuel ratio is supplied to the gas burner 6.

Here, it is desired to quickly switch the combustion state of the gas burner 6 from the strong combustion state to the weak combustion state due to the temperature control control for adjusting the room temperature to the target range. Temperature, the internal temperature of the FF gas hot air heater 1, especially the heat exchanger
The surface temperature of 61 does not drop immediately. Therefore, the convection blower 3 is controlled as follows.

In the convection blower 3, the electric motor 31 is energized with the maximum energization amount until the second holding time (for example, 5 seconds) elapses.
Thereafter, as the combustion state of the gas burner 6 decreases stepwise, the air flow of the convection fan 32 decreases stepwise every time a second holding time longer than the first holding time elapses from a strong airflow to a weak airflow. To go. Thus, the stepwise decrease in the amount of air blown by the convection fan 32 is such that as the combustion state of the gas burner 6 decreases stepwise, the delay time becomes longer with respect to the switching timing of the combustion state of the gas burner 6 as the airflow decreases.

Therefore, according to the combustion state of the gas burner 6, the room air drawn into the hot air duct 2 from the suction port 21 by the rotation of the convection fan 32 is heated when passing around the heat exchanger 61 and is heated to a predetermined temperature. It becomes warm air. In addition, when the room air passes through the hot air duct 2, the inside temperature of the FF gas hot air heater 1 that has been operated in the strong combustion state decreases.

Therefore, when switching the combustion state of the gas burner 6 from the strong combustion state to the weak combustion state, as the combustion state of the gas burner 6 decreases stepwise, the FF gas hot air heater 1
, In particular, the temperature of the heat exchanger 61 can be gradually reduced to an optimum temperature according to the combustion state of the gas burner 6. For this reason, when the combustion state of the gas burner 6 is switched from the strong combustion state to the weak combustion state, the convection fan 32 does not immediately switch from the strong air flow to the weak air flow.
The microcomputer 10 and the thermistor 11 are controlled by preventing the inside temperature of the gas hot air heater 1 from being exposed to a high temperature.
In addition, malfunction of electric equipment such as the overheat safety device 17 can be prevented.

When the second holding time has elapsed, the convection blower 3
The amount of current supplied to the electric motor 31 is reduced to the seventh level. Thereafter, the amount of current supplied to the electric motor 31 decreases by one step each time the second holding time elapses until the amount of current supplied to the electric motor 31 becomes the minimum amount of current supplied.

That is, the amount of current supplied to the electric motor 31 gradually decreases every time a second holding time (for example, 5 seconds) longer than the first holding time elapses from the maximum current to the minimum current. (See the graph in FIG. 2).

Therefore, the air flow of the convection fan 32 is delayed from the combustion state of the gas burner 6, and is switched from the strong air flow to the weak air flow through six air flow stages. Therefore, the convection fan is switched from the combustion state of the gas burner 6 until the air flow is switched from the strong air flow to the weak air flow.
Since the amount of air blown by the fan 32 is relatively large, the inside of the FF gas hot air heater 1 is cooled by the convection fan 32 as described above. In addition, the convection fan 32 does not maintain the strong air flow for a long period of time (for example, 35 seconds) before switching from the strong air flow to the weak air flow. That is, since the operation time of the strong air flow is reduced, and the air flow of the convection fan 32 is not suddenly switched from the strong air flow to the weak air flow, the inside of the FF type gas hot air heater 1 is not excessively cooled. Therefore, the heating feeling such as the blowing of cold air from the hot air duct 2 toward the room is not hindered.

Further, when the combustion state of the gas burner 6 decreases stepwise, the air volume of the convection fan 32 decreases with a delay toward the low air volume side, so that the internal temperature of the FF type gas hot air heater 1, especially the heat exchanger The temperature of 61 can be gradually lowered without blowing cold air or increasing the temperature inside the machine.

(Modification) In this embodiment, the fuel gas is used as the fuel, but a liquid fuel may be used as the fuel.

In the present embodiment, the present invention is used for an FF type gas hot air heater, but the present invention may be used for another hot air heater such as a fan heater.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a configuration diagram showing a schematic structure of an FF type gas hot air heater, FIG. 2 is a graph showing a change in a convection fan's blowing amount with respect to a gas amount change, and FIG. 3 is a main control of a microcomputer. FIG. 4 is a subroutine showing weak combustion control of the microcomputer. In the figure: 1 ... FF gas hot air heater, 2 ... Hot air duct,
3 ... convection blower, 4 ... combustion duct, 5 ... combustion blower, 6 ... gas burner (burner), 10 ... microcomputer (combustion control means, blow control means), 11 ...
... Thermistor (Temperature detection means), 15 ... Temperature adjustment button (Temperature setting means), 32 ... Convection fan, 61 ... Heat exchanger, 74 ... Proportional control valve

Claims (1)

(57) [Claims] 1. A hot air duct for sending air toward a room, a convection blower for generating an air flow toward the room in the hot air duct, and a fuel for burning the inside of the hot air duct by burning fuel. A burner that heats the passing air; a heat exchanger that heats the air passing through the hot air duct by exchanging heat with the combustion heat of the burner; a temperature detecting unit that detects an indoor temperature; Temperature setting means for setting a temperature; combustion control means for controlling a combustion state of the burner in accordance with a detected temperature detected by the temperature detection means and a target temperature set by the temperature setting means; Blower control means for controlling the amount of air blown by the convection blower according to the combustion state of the air conditioner.The combustion control means switches the combustion state of the burner from a strong combustion state to a weak combustion state. In this case, the combustion state of the burner is decreased stepwise every time the first holding time elapses from the strong combustion state to the weak combustion state, and the blower control means reduces the combustion state of the burner stepwise. As a result, the amount of air blown by the convection blower is gradually decreased from a strong air flow to a weak air flow every time a second holding time longer than the first holding time elapses. A stepwise decrease in the amount of air blown by the convection air blower is further delayed as the air flow decreases.