JPH0330699Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a combustion safety device in a forced draft combustor having a fan whose rotation speed is controlled.

(Prior Art and Problems) Conventionally, in a forced draft combustor, if back pressure was applied to the exhaust section, a wind pressure switch would detect this and stop combustion. However, in the case of a composite combustor that discharges exhaust gas from a plurality of combustors together, the influence of back pressure differs between single combustion and simultaneous combustion. In other words, for example, in the case of a bathtub with a water heater, even with the same reverse pressure, combustion occurs normally when hot water is supplied alone, but when hot water and bathing are simultaneously combusted, the water heater may cause abnormal combustion due to the influence of the exhaust from the bathtub. . Because of this, combustion was stopped at the limit of simultaneous combustion regardless of simultaneous combustion or single combustion, so combustion stopped even though it was normal during single combustion, making it difficult to withstand. There was a problem that the back pressure limit was small and combustion frequently stopped.

The present invention is intended to solve the above-mentioned conventional problems, and will be explained below based on examples of drawings.

(Example) 1 is a heat exchanger for a bathtub, and burner 2 with a constant capacity
and an exhaust fan 3 with a constant rotation speed for forcibly exhausting combustion air. 4 is a heat exchanger for a water heater, which includes a variable capacity burner 5 and a burner 5 that transfers combustion air.
A rotation speed controlled air supply fan 6 is provided to forcefully supply air according to the capacity of the engine. Reference numeral 7 denotes an exhaust connection pipe that connects the exhaust fan 3 to the exhaust collecting pipe 8 above the hot water supply heat exchanger 4. Reference numeral 9 denotes an exhaust pipe, which discharges the exhaust gas from both the bathtub and the water heater from the exhaust collecting pipe 8 to the outside of the appliance. Reference numeral 10 denotes a pressure detection tube that guides the pressure inside the exhaust pipe 9 to wind pressure switches PS1 and PS2, which are branched. The first wind pressure switch PS1 is
When a headwind or the like is applied to the exhaust stack 9, the back pressure is detected based on the pressure increase, and is set to the limit pressure for simultaneous combustion (for example, 5 mmH20). The second wind pressure switch PS2 is set to the limit pressure for independent combustion when the capacity of the water heater is high (for example, 14 mmH20), and has a higher response pressure than the first one. Reference numeral 11 denotes a controller that controls the rotational speed of the air intake fan 6 and combustion based on signals from both wind pressure switches.

Next, the effect of the above configuration when there is a headwind will be explained. First, it is determined whether or not there is simultaneous combustion (S1).

Next, the rotation speed Qrpm of the air supply fan 6 of the water heater
It is checked whether the predetermined rotation speed L is on the low side (S2). If the rotational speed is equal to or higher than L, then it is checked whether the rotational speed is a higher predetermined rotational speed H (S3). If the rotational speed Qrpm is between L and H, the current combustion state is continued (S4). When the rotational speed Qrpm is lower than L, that is, when the capacity is small, the ON/OFF state of the first wind pressure switch (PS1) is checked (S5). If there is a headwind, the pressure inside the exhaust stack 9 will increase, so the first wind pressure switch PS1 will turn on.
Upon receiving the ON signal, the controller 11 turns on the air supply fan 6.
A command is issued to increase the rotation speed Qrpm to L (S6). The increased rotational speed prevents exhaust gas from the bath from flowing to the hot water supply side due to back pressure and inhibiting combustion. If more reverse pressure is applied, the second wind pressure switch PS2 is turned on (S7),
All combustion is stopped (S8). Also, rotation speed
When Qrpm is higher than the predetermined rotation speed H on the high side, that is, at high capacity, the first wind pressure switch PS1 is turned on and off.
(S9), and if it is ON, set the rotation speed Qrpm to H.
(S10). As the rotation speed decreases,
This prevents exhaust gas from the hot water supply side from flowing to the bath side, which has a smaller capacity, from being pushed by back pressure and inhibiting combustion. If a higher back pressure is applied, the second wind pressure switch PS2 is turned on (S11) and all combustion is stopped (S8). That is, as shown in FIG. 2, when there is a reverse pressure during simultaneous combustion, the rotational speed of the water heater is shifted within a predetermined range that is smaller than the limit during independent combustion.

(Effects of the invention) As described above, the invention has a fixed capacity combustor,
In a composite combustor that shares an exhaust passage with a variable capacity combustor that has a fan whose rotation speed is controlled,
During simultaneous combustion, a first wind pressure switch narrows the limit of the fan rotation speed when the exhaust passage pressure exceeds a predetermined pressure, and a second wind pressure switch is set to a response pressure higher than the response pressure of the first wind pressure switch and stops combustion. This prevents the exhaust from the variable capacity combustor from being suppressed when the capacity is low and causes abnormal combustion such as overflowing of flames, and prevents the exhaust from the fixed capacity combustor from being suppressed when the capacity is high and causes abnormal combustion. This can be prevented and the limit of back pressure resistance can be improved.

[Brief explanation of drawings]

The drawing shows one embodiment of the present invention.
2 is a diagram showing the overall configuration, FIG. 2 is a diagram showing the relationship between the combustion capacity of the water heater and the fan rotation speed, and FIG. 3 is a flowchart showing the operation during simultaneous combustion. 1... Heat exchanger for bath kettle, 2... Fixed capacity burner, 4... Heat exchanger for water heater, 5... Variable capacity burner, 6... Rotation speed controlled fan, 8... Exhaust manifold, 9... Exhaust pipe, PS1... First wind pressure switch, PS2... Second wind pressure switch.

Claims (1)

[Scope of utility model registration request] In a composite combustor that shares an exhaust passage with a fixed capacity combustor and a variable capacity combustor with a fan whose rotation speed is controlled, when the exhaust passage pressure exceeds a predetermined pressure during simultaneous combustion, the rotation speed of the fan changes. A combustion safety device comprising: a first wind pressure switch that narrows the limit; and a second wind pressure switch that is set above the response pressure of the first wind pressure switch and stops combustion.