JP3033362B2 - Hot air heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot air heater having a function of preventing abnormal heating of equipment due to abnormal operation due to air intake blockage, air outlet blockage, blower fan stop, and the like.

[0002]

2. Description of the Related Art A conventional safety device for preventing overheating of a hot air heater uses a bimetal switch as a heat-sensitive element, a bimetal contact is normally conducted, and a bimetal switch is used when an abnormal temperature rise of a heat exchanger or the like. At the set temperature of the switch, conduction of the bimetal switch contact was lost, and the operation of the appliance was stopped.

[0003]

In the conventional bimetal switch system, when the air intake is blocked, when the air outlet is blocked, when the appliance is overturned, when the burner gas volume increases, when the blower fan is stopped, etc. The temperature in the vicinity of the switch rises sharply due to insufficient ventilation, but the operation of the appliance could not be stopped quickly due to the large heat receiving capacity of the bimetal switch and the low temperature sensing speed. In particular, when the degree of air shortage was large, the temperature was rapidly increased, and there was also burning of equipment and a large amount of smoke.

Accordingly, the present invention provides a temperature rise value and a temperature rise detected by a thermistor when the air intake is blocked, when the hot air outlet is blocked, when the appliance is turned over, when the burner burns up, or when the blower fan is stopped. The purpose of the system is to detect abnormalities in equipment according to the rate and stop the operation of the equipment early to prevent abnormal overheating.

[0005]

In order to achieve the above object, a hot air heater according to the present invention comprises a burner combustion gas and indoor air.
A heat exchanger that mixes air with hot air, and this heat exchanger
Supply indoor air and blow warm air from the heat exchanger into the room.
Blower fan and indoor air supplied to the heat exchanger
A filter provided at the air inlet and the heat exchanger
Heat exchanger to form a hot air passage with the heat exchanger
Bar and heat exchange so as to detect the outer wall temperature of the hot air passage
A thermistor provided on the outer surface of the container cover, and the thermistor
Overheat prevention that controls the combustion of the burner based on the output of the burner
And a determiner, wherein one end of the heat exchanger cover is empty.
The filter is positioned so that the intake port is divided
Some of the air that passed through flows into the heat exchanger while the rest
Cool outside the heat exchanger cover to cool the thermistor
And the overheat prevention judging device is configured to
The temperature set value detected by the
Then, it is determined that the burner has stopped burning, and the temperature rise value
Even if the set temperature has not been reached, the unit time
The temperature rise rate of the hot air passage per hit exceeds the reference temperature rise rate
When it comes to this, the burner combustion stop is determined and instructed.
It is.

[0006]

According to the above-mentioned means, the present invention provides an overheat temperature judging device which detects a small temperature rise value per unit time by a signal from a thermistor when the amount of air blown by a blower fan is slightly reduced due to an air intake blockage or the like. Performs abnormality detection at a predetermined temperature.

Further, if a large temperature rise rate is detected per unit time when the blown air amount is greatly reduced, for example, when the blower fan is not driven, an instruction to stop the appliance is given separately from the predetermined temperature, and the predetermined temperature is reached. Before the operation, abnormal operation can be stopped at an early stage to ensure the safety of use of the equipment.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a hot air heater according to an embodiment of the present invention.

FIG. 1 shows an embodiment of the present invention.
The hot air burned in is passed through the heat exchanger 2 by the suction force of the blower fan 12 and is blown out of the hot air outlet 3 by the suction force of the blower fan 12. The required combustion air in the burner 1 is filtered by an air intake filter 5 attached to the main body back plate 4.
It is taken in from passage a. The air from the passage b passes through the upper part of the heat exchanger 2 and passes between the main body front plate 6 and the air duct 8 of the heat exchanger 2, cools the main body front plate 6 and the front air duct 8 and blows air. It is sent to the fan 12. The thermistor 7 is brought into contact with the upper part of the front air duct 8 to detect the surface temperature.

A burner 1 is provided inside the heat exchanger 2. A mixture of air taken in from a passage C of a filter 5 and a combustion gas of the burner 1 is supplied to a front air duct 8 and a rear air duct. Flow between 9 In the lower part of the main body, a sequence circuit 1 for driving and controlling the burner 1 and the blower fan 12
4 comprising a controller 15 having The controller 15 receives the detection signal of the thermistor 7, first determines a temperature rise value per unit time, and also includes an overheat prevention determiner 16 for instructing the burner 1 to stop operating according to the temperature rise value.

The front air duct 8 includes a mixture of air flowing between the top duct 10 and the heat exchanger cover 11.
The thermistor 7 is attached by contacting the air flowing through the heat exchanger cover 11 and the front plate 6 of the main body to keep the burner 1 at a relatively low surface temperature while avoiding contact with the high-temperature combustion gas.

Next, as an example of abnormal air circulation, when the air intake is blocked due to dust clogging or the like, the suction resistance of the blower fan 12 from the filter 5 increases, and the suction amount decreases. The inflow of air from the passage C between the heat exchanger covers 11 and the like decreases, the cooling degree of the front and rear ventilation ducts 8 decreases, and the ducts 8 are heated and the detection temperature of the thermistor 7 increases.

When the blower fan 12 is stopped due to a failure or the like, the combustion gas of the burner 1 heats the upper duct 10 and the front blower duct 8 by rising hot air, and the thermistor 7
Detects a high temperature rise.

Referring to FIG. 2, in the case B, dust adheres to the filter 5 at the air intake, the intake resistance gradually increases, the cooling air from the passage C decreases, and the temperature of the mixture increases. 5 shows a case where the temperature rise value 13 detected by the thermistor 7 is gentle. In the case A, the cooling air hardly disappears due to the stop of the blower fan 12, and the temperature rises rapidly.

The causes of the case B include slight blockage of the air outlet, blockage of the air intake, increased burner combustion gas, adhesion of dust to the fan blades of the blower fan 12, dust clogging of the filter 5, and the like. The causes of the cases A and A correspond to the filter 5 and the outlet 3 being closed due to the failure stop of the blower fan 12 and the fall of the appliance. In addition, as a matter of course, an intermediate case in which the temperature rise per unit time is larger than that in case B but not as large as case A is also conceivable.

In the case C, the conventional high limit switch detects the set temperature Ts (70 ° C.) at a slow temperature sensing time and requires time t ₃ . Compared with this, the thermistor 7 can detect the set temperature Ts earlier at a time t ₂ shorter than the time t ₃ because the heat receiving capacity is small. Even if the same abnormal operation occurs, the overheat prevention determination unit 16 promptly detects the set temperature Ts. Abnormal and bad operation can be stopped.

The overheat prevention judging device 16 is a case A or a case B
In the abnormal operation, a signal from the thermistor 7 is received to first detect a temperature rise value ΔT in a predetermined short time Δt. Then, the average temperature rise rate per unit time is calculated as ΔT / Δt = ΔT1, and compared with the reference temperature rise rate ΔTs set for judging Case A. If Δ
If it is determined that T1 <ΔTs, the operation is continued. If the signal from the thermistor 7 exceeds the set temperature Ts, the sequencer 14 is instructed to stop the burner 1 and the blower fan 12, and the abnormal operation is stopped. .

The temperature rise rate ΔT1 detected by the overheat prevention judgment unit 16 is larger than the reference temperature rise rate ΔTs, ΔT1 ≧ Δ
At the time of Ts, the cooling air from the passage C becomes extremely short, and the heat exchanger 2 is overheated, and the main body is radiated by high-temperature radiation from the front air duct 8 and the heat exchanger cover 11 of the heat exchanger 2. Overheating of each part occurs rapidly in a short time. Therefore, the overheat prevention judging device 16 detects the temperature rise rate .DELTA.T1 at the time t1 and, at the same time, instructs the sequence circuit 14 to immediately instruct the dangerous operation to stop. At this time,
Even when the surface temperature of the front air duct 8 around the thermistor 7 is lower than the set temperature Ts, the temperature increase rate ΔT1 can be detected. The degree of overheating of the heat exchanger 2 and the like can be suppressed as compared with the case where the operation is stopped at Ts.

As described above, in the case where the supply of air to the heat exchanger 2 is critically short as in the case A, the set temperature T
s to prevent unnecessary and dangerous overheating after waiting to reach s, and by measuring and determining the temperature rise rate ΔT1,
The abnormal operation time such as the stop of the blower fan 12 can be completed in a short time. When the temperature rise rate ΔT1 is lower than the reference temperature rise rate ΔTs, a reference temperature rise rate ΔTs2 <ΔTs may be provided for the intermediate case. In case B, in which the intermediate case is not provided, when the degree of dust clogging is light, the temperature does not always reach the set temperature Ts. Therefore, it is monitored whether or not the temperature reaches the set temperature Ts. When reaching Ts, the operation was considered to be unsafe and the operation was stopped.

[0020]

As described above, the warm air heater according to the present invention includes a thermistor as a heat-sensitive element and an overheat prevention judging device for judging a signal of the thermistor. If the air supply is significantly short and a large temperature rise occurs per unit time,
Until the temperature rise value reaches the set temperature , the temperature rise rate
What abnormal detection can be performed, abnormal overheating occurs during early burnout of the instrument, it can be performed with no safe shutdown fuming. Also
Thermistor exchanges heat to detect outer wall temperature of hot air passage
On the outer surface of the heat exchanger cover and one end of the heat exchanger cover
Filtering the air intake so as to divide it
Some of the air that passed through flows into the heat exchanger and remains
Flows outside the heat exchanger cover to cool the thermistor
Thermistor temperature is relatively low
Inexpensive low-temperature thermistors that can be used can be used.
The air that has passed through one filter into the combustion gas
To separate the air for cooling and the air for thermistor cooling.
Even if dust gets stuck in the filter,
The air to be mixed and the air for thermistor cooling have almost the same ratio.
Only air mixed with the combustion gas
The temperature dropped sharply and the hot air temperature increased during normal operation.
Or only the thermistor cooling air drops, resulting in weak combustion.
Is not overheated but only the thermistor temperature rises
Can be prevented from malfunctioning.
Also has the advantage of being able to improve the reliability of
is there.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a hot air heater according to the present invention.

FIG. 2 is a characteristic diagram showing a thermistor temperature rise value and the like when the blower fan is stopped.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Burner 2 Heat exchanger 7 Thermistor 8 Front ventilation duct 12 Fan for ventilation 16 Overheat prevention judgment device

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Honda 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-1-281325 (JP, A) JP-A-63- 213722 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F23N 5/14 370 F24H 3/04 305

Claims (1)

(57) [Claims] 1. A heat exchanger that mixes combustion gas from a burner with room air to generate hot air, and supplies indoor air to the heat exchanger.
And a blower fan for blowing warm air from the heat exchanger into the room, and an air inlet for room air supplied to the heat exchanger.
Girder filter and the heat exchanger covering the heat exchanger.
A heat exchanger cover forming a hot air passage between
The outer surface of the heat exchanger cover to detect the temperature of the outer wall of the wind passage
Based on the output of the thermistor
And an overheat prevention determiner for controlling the combustion of the burner.
One end of the heat exchanger cover separates the air intake.
Air that has passed through the filter
Part of the heat flows into the heat exchanger and the rest
To cool the thermistor by flowing outside
And the overheat prevention determiner is operated by the thermistor.
When the detected temperature set value exceeds the set temperature, the burner
In addition to judging combustion stoppage, the temperature rise value is set at the set temperature.
Hot air per unit time, even if it has not reached
A hot-air heater configured to instruct a burner to stop burning when a passage temperature rise rate is equal to or higher than a reference temperature rise rate .