JPH0282015A - Combustion control device for heater - Google Patents

Abstract

PURPOSE:To enable a stable combustion with less variation of concentration of CO2 in exhaust gas to be carried out by a method wherein an amount of combustion air and amount of fuel are increased or decreased substantially in a comparative manner according to a degree of load and an amount of combustion is adjusted in response to a temperature of combustion air heat exchanged with the exhaust gas. CONSTITUTION:As an operation switch 29 is turned on, an amount of combustion air and an amount of oil are increased or decreased substantially in a comparative manner in response to a degree of load. Combustion is carried out in a burner 2 at an amount of combustion corresponding to a load while an air fuel ratio is being kept substantially constant. An air fuel ratio correcting means 25 may adjust a frequency of a fuel pump 5 in response to a temperature signal of combustion air heat exchanged with exhaust gas sent from an air temperature sensor 14. That is, at the beginning of combustion with a low combustion air temperature, an amount of fuel is much in compliance with an air specific weight and a lifting combustion is prevented and at the same time as the combustion air temperature is increased through a heat exchanging action with the exhaust gas so as to prevent a red heat combustion. Combustion under the most appropriate ratio always causes a concentration of CO2 in the exhaust gas to be substantially constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a combustion control device for a heater such as an outdoor air supply/exhaust type heater.

(b) Conventional technology Conventionally, as disclosed in Japanese Patent Publication No. 62-33496, for example, in a hot air heater using a gasification type burner that gasifies and burns liquid fuel such as kerosene, By controlling the rotation speed of the burner motor according to the heating load and increasing or decreasing the amount of oil sent by the combustion pump according to the rotation speed of the burner motor, the air-fuel ratio is kept almost constant and the combustion state of the burner is maintained in good condition. The amount of combustion can be switched between high and low levels.

(C) Problems to be Solved by the Invention By the way, the above-mentioned heater is an outdoor air supply/exhaust type using an air supply/exhaust pipe, an air supply pipe, and an exhaust pipe, and takes in outdoor air as combustion air and directs the exhaust gas outdoors. I am trying to release it to At this time, since the combustion air is completely heated by exchanging heat with the exhaust gas in the supply and exhaust pipe, the temperature of the combustion air blown to the burner by the burner fan gradually increases after combustion starts. As the air-specific weight changes with such changes in the combustion air temperature, the amount of oxygen per unit volume increases or decreases, so there is a concern that the air-fuel ratio will collapse and the combustion state will worsen. That is, when the air temperature is low, there is an excess of air, resulting in lifting combustion, and when the air temperature is high, there is insufficient air, resulting in red-fire combustion, resulting in unstable combustion.

This invention was made in view of the above facts,
By heat exchange between exhaust gas and combustion air, the air-fuel ratio is maintained appropriately even if the combustion air temperature changes significantly, and stable combustion is performed with little change in CO and a degrees in the exhaust gas. The purpose is to

(d) Means for Solving the Problems The combustion control device for a heater according to the present invention supplies combustion air heat-exchanged with exhaust gas and fuel to a burner to cause combustion, and utilizes the combustion heat of the burner. In a heater that heats indoor air using a combustion engine, the combustion amount control means increases or decreases the amount of combustion air and fuel approximately proportionally according to the size of the load, and the amount of combustion air that exchanges heat with exhaust gas is This configuration includes air-fuel ratio correction means that detects the temperature and adjusts the amount of fuel according to the air temperature.

Further, the combustion control device for a heater of the present invention includes a burner, a burner fan that blows combustion air to the burner, a fuel pump that sends fuel oil to the burner, and air heated by the combustion heat of the burner to the room. In a heating machine that is equipped with a heating machine body having a blower fan that discharges air to A combustion amount control means that increases or decreases the amount of air blown by the burner fan and the amount of oil sent by the fuel pump approximately proportionally according to the size of Detects temperature,
This configuration includes air-fuel ratio correction means for adjusting the amount of oil fed by the fuel pump in accordance with the air temperature.

Furthermore, in such a combustion control device for a heater, a detector for detecting combustion air temperature is provided in an air passage between an air supply pipe and a burner fan.

(f) Effect With this configuration, the amount of combustion air and the amount of fuel change approximately proportionally depending on the size of the load, and the amount of combustion in the burner is increased or decreased while the air-fuel ratio is kept approximately constant. The burner performs combustion commensurate with the load. In addition, since the amount of fuel is adjusted to follow the temperature change of the combustion air supplied to the burner, combustion is always performed at the optimal air-fuel ratio, regardless of the rise in combustion air temperature due to heat exchange with exhaust gas. It will be done.

In addition, in an outdoor air supply/exhaust type heater equipped with an air supply/exhaust pipe, an air supply pipe, and an exhaust pipe, even if the combustion air temperature fluctuates due to heat exchange between exhaust gas and combustion air in the supply/exhaust pipe,
Combustion is always performed in the burner at an optimal air-fuel ratio, and the CO1 concentration in the exhaust gas is kept approximately constant.

Furthermore, in an outdoor air supply/exhaust type heater, by providing a detector for detecting combustion air temperature in an air passage between an air supply pipe and a burner fan, the detector is less likely to receive combustion heat from the burner.

(f) Example Hereinafter, embodiments of the present invention shown in the drawings will be described.

Figure 4 shows an outdoor air supply/exhaust type heater to which this invention is applied, and (1) shows a burner (2);
), the heat exchanger (3), the blower fan (4), and the fuel oil in the cartridge tank (not shown) are transferred to the burner (2).
The main body of the heating machine, which houses the fuel pump (5) etc. that sends oil to the
<6) is installed through the wall (7) and is connected to the air supply path (6).
(8) is an air supply pipe for guiding the outdoor air that has flowed into the air supply path (6A) to the burner (2); ) is a heat exchanger (3
) is an exhaust pipe for guiding the exhaust gas that has undergone heat exchange to the exhaust passage (6B) of the supply/exhaust pipe (6). Heating machine body (1)
The indoor air sucked in from the upper part of the back by the blower fan (4) is heated by heat exchange with the combustion gas in the heat exchanger (3), and hot air is sent into the room from the warm air outlet (10) at the lower part of the front. It will be discharged.

As shown in Fig. 5, the burner (2) consists of a blower section (2A) and a combustion section (2B), and the blower section (2A) has a fan case (11) connected to an air supply pipe (8). , the burner motor (BM), the burner fan (13) attached to the rotating shaft (12) of the burner motor (BM), and the burner fan (13) and air supply pipe (8) inside the fan case (11). An air temperature sensor that detects the air temperature between
14) are provided. The combustion section (2B) includes a vaporizer cylinder (16) having a heater (15) and a rotating shaft (12).
A rotary cone (17) and a mixing plate (18) for fuel atomization, which are attached to the tip of the fuel atomizer and inserted into the base of the vaporizer cylinder (16), and a rotary cone (
An oil feed vibrator (19) that drips fuel oil into the tank (17), and a regulator pipe (20) attached to the middle part of the carburetor (16).
, a porous heat shield plate (21), a burner head (22) attached to the tip of the vaporizer cylinder (16), a secondary air guide plate (23), and a porous heat shield plate (21) in front of the burner head (22). The positioned flame rod (24) and spark plug (25)
) is provided.

In the burner (2) described above, the air supply path (6) of the supply and exhaust pipe (6)
A) Combustion air is supplied to the combustion section (2A) via the air supply pipe (8) and the blower section (2A). In addition, a heater (1
After the carburetor cylinder (16) is heated in advance by step 5), the fuel pump (5) is fully operated and the fuel oil is sent to the oil feeding vibrator (19).
It passes through the rotary cone (17) and drips into the rotary cone (17). The fuel atomized by the rotary cone (17) absorbs vaporization heat from the vaporization tube (16) and vaporizes. This vaporized fuel and the primary air that has flowed into the vaporization cylinder (16) are mixed by the mixing plate (18), and the
0) and the burner head (22) through the heat shield plate (21).
heading to Since secondary air is supplied to the tip of the vaporization tube (16), the gas mixture of vaporized fuel and combustion air is gasified and burned in front of the burner head (22).

FIG. 1 shows the combustion control device for the above-mentioned heater. In FIG. 1, (26) is a microcomputer, (27) and (28) are respectively a combustion amount control means and an air-fuel ratio correction means built into the microcomputer (26), (29) is an operation switch, and (30) is a temperature setting switch for setting the desired indoor temperature, (31) is a room temperature detector, (32) is a rotation speed detector that detects the rotation speed of the burner motor (BM), (FM) is a blower fan (4) This is a blower motor for driving.

When the operation switch (29) is turned on, the combustion amount control means (27) first energizes the vaporization heater (15). When the temperature signal from the burner thermistor (not shown) confirms that the carburetor cylinder (16) has been sufficiently heated, the burner motor (BM) and fuel pump (5) are sequentially activated, and the spark plug (25) is activated. ) to activate the burner (2).
so that combustion takes place. In addition, the operation switch (2
9), the temperature difference between the desired temperature set by the temperature setting switch (30) and the room temperature detected by the room temperature detector (31) is determined, and the temperature is adjusted according to the size of the load as shown in Figure 2. Determine the combustion amount Q. Then, the rotation speed of the burner motor (BM) is controlled so that an air flow rate suitable for this combustion amount Q can be obtained. The rotation speed of the burner motor (BM) can be detected by the rotation speed detector (32>), and the rotation speed signal is input to the combustion amount control means (27).The combustion amount control means (27) controls the burner motor based on this rotation speed signal. At the same time, the rotation speed control signal to the combustion pump (BM) is corrected, and the combustion pump (5)
(electromagnetic pump). Therefore, the amount of combustion air and the amount of fuel oil supplied are increased or decreased approximately proportionally depending on the size of the load, and the air-fuel ratio is maintained approximately constant in the burner (2). combustion is performed at a combustion amount commensurate with the load. Further, the rotation speed of the blower motor (FM) is adjusted according to the combustion amount, and the temperature of the air discharged from the hot air outlet (10) is appropriately adjusted according to the combustion amount.

The air-fuel ratio correction means (28) adjusts the frequency of the fuel pump (5) as shown in FIG. 3 according to the temperature signal sent from the air temperature sensor (14). 14) When the detected temperature is 40°C or higher, the frequency increase rate of the fuel pump (5) is set to O, and the temperature increases from 40'C to -2
In the range of 0°C, increase the pump frequency by 0.3% for each 1°C decrease based on 40°C, and -20°C.
In the following, the rate of increase in pump frequency is assumed to be constant at 18%.

The reason why the rate of increase above 40'C was set as O is because heaters are mainly used in winter, and the detected temperature rarely exceeds 40°C. In addition, the increase rate below -20°C was set constant because the heating unit (1) is installed indoors, and the lower limit of temperature in this part is thought to be approximately -20°C in Japan. It is. When such air-fuel ratio correction is performed,
From the air supply pipe (8) to the fan case (as at the beginning of operation)
11) When the temperature of the air flowing into the combustion chamber is low and the specific weight of the combustion air is high, the pump frequency increases, which not only prevents excessive air flow and prevents lifting combustion, but also increases the heating capacity. The larger the size, the faster the room temperature will rise. Furthermore, after the start of combustion, as the temperature detected by the air temperature detector (14) increases due to heat exchange between exhaust gas and combustion air in the supply and exhaust pipe (6), the rate of increase in the amount of oil fed becomes smaller. It can prevent red flame combustion due to lack of air. Since such air-fuel ratio correction is performed regardless of the size of combustion flcQ, burner (2) always performs combustion at the optimal air-fuel ratio, and stable gasification combustion is expected with the COt concentration in the exhaust gas being approximately constant. can. Furthermore, since the air temperature sensor (17) is installed inside the fan case (11) between the air supply pipe (8) and the burner fan (13), the influence of heat from the combustion section (2B) is reduced. At the same time, the combustion air temperature can be accurately detected.

(g) Effects of the Invention Since the present invention is configured as described above, in a device that heats combustion air with exhaust gas to efficiently perform gasification combustion, The fuel amount can be increased to match the air specific weight to prevent lifting combustion, and as the combustion air temperature rises due to heat exchange with the exhaust gas, the fuel amount can be suppressed to prevent red-flame combustion. It is possible to achieve stable combustion in which combustion is always performed at the optimum ratio and the C concentration in the exhaust gas is approximately constant, such as by preventing suitable for

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a combustion control device for a heater showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of load-combustion amount characteristics,
Fig. 3 is an explanatory diagram showing the relationship between air temperature and pump frequency increase rate, Fig. 4 is an explanatory diagram of a schematic configuration of a heater, and Fig. 5 is a sectional view showing an example of a burner used in the heater. be. (1)...Heater body, (2)...Burner, (
4)...Blower fan, (5)...Fuel pump,
(6)...Intake and exhaust pipe, (6A)...Air supply path, (
6B)...Exhaust path, (8)...Air supply pipe, (9)
...exhaust pipe, (13) ...burner fan, (1
4)...Air temperature detector, (27)...Combustion amount control means, (28)...Air-fuel ratio correction means. 17th oval! Figure 4

Claims (2)

[Claims] (1) In a heater that heats indoor air by supplying combustion air that has exchanged heat with exhaust gas and fuel to a burner and combusts it, using the combustion heat of the burner, combustion is performed according to the size of the load. Combustion amount control means that increases or decreases the amount of air and fuel used approximately proportionally; and Air-fuel ratio correction means that detects the temperature of combustion air that has exchanged heat with exhaust gas and adjusts the amount of fuel according to this air temperature. A combustion control device for a heater comprising: (2) Main body of the heater, which includes a burner, a burner fan that blows combustion air to the burner, a fuel pump that feeds fuel oil to the burner, and a blower fan that blows air heated by the combustion heat of the burner into the room. In a heating machine equipped with an air supply pipe and an exhaust pipe having an air supply path and an exhaust pipe, and an air supply pipe and an exhaust pipe that connect the main body of the heater and the supply and exhaust pipe, the burner fan is A combustion amount control means that increases or decreases the air volume and the amount of oil sent from the fuel pump approximately proportionally, and a combustion amount control means that detects the temperature of the combustion air that has flowed into the heater body through the supply/exhaust stack and the air supply pipe, and responds to the air temperature. A combustion control device for a heater, comprising an air-fuel ratio correction means for adjusting an oil supply amount of a fuel pump. (3) The combustion control device for a heater according to claim 2, wherein a detector for detecting combustion air temperature is provided in an air passage between the air supply pipe and the burner fan.