JPH02192512A - Forced feed and discharge type combustion device - Google Patents

Abstract

PURPOSE:To prevent worsening of combustibility due to the influence of a feed air temperature by a method wherein a discharge cylinder and a feed cylinder are formed in a double-pipeform manner, the number of revolutions of a fan is stepwisely increased from low rotation to the predetermined number of revolutions responding to a combustion amount and is finally controlled to the predetermined number of revolutions. CONSTITUTION:A feed cylinder 7 is concentrically located outside an discharge cylinder 6 to form a double-pipeform feed and exhaust cylinder 8. The optimum number of revolutions (stable combustion state) of a fan 9 responding to a combustion amount G of a burner 4 is predetermined as the predetermined number of revolutions. When ignition is detected, a combustion amount computing means 24 computes a combustion amount, and a clock pulse generating means 19 is actuated. A first number of revolutions set means 18 outputs the predetermined number of revolutions responding to a combustion amount, a second number of revolutions set means 20 outputs the set number of revolutions according to an output pulse from a clock pulse generating means 19, and a fan 9 is controlled to the set number of revolutions outputted from the second number of revolutions set means 20. When a feed air temperature during the initial stage of ignition is low, the number of revolutions is gradually increased from low rotation to prevent lifting of flame.

Description

[Detailed description of the invention] <Field of use of Pfi industry-F) The present invention relates to a forced air supply/exhaust type combustion device.

(Prior art) Conventionally, in forced air supply and exhaust combustion VtH such as water heaters,
For example, as shown in Japanese Utility Model Application Publication No. 62-172935, the exhaust pipe and the supply cylinder are formed into a double pipe shape, and the supply cylinder and the suction port of the fan are connected via a duct, and the tip of the supply cylinder is Some devices are designed to direct the intake air to a fan.

(Problem to be solved by the invention) In this conventional system, heat transfer occurs between the supply air and the exhaust air in the double-tubular supply and exhaust pipe, so the temperature of the supply air gradually increases after the burner ignites. However, during stable combustion, the supply air temperature is considerably higher than at the initial stage of ignition, and the fan rotation speed is adjusted in advance according to the gas amount so that the appropriate amount of air is obtained during stable combustion. Since the temperature of the supply air is low and the air density is high in the early stage of ignition, there is an excess of air, which has the disadvantage of deteriorating combustibility, such as lifting of the flame.

Further, in this conventional device, a similar IJi phenomenon occurs also in the following cases. In other words, when the capacity is significantly changed by changing the number of combustion burners, when the capacity is low, the exhaust temperature is low, so the supply air temperature is low, and when switching from the low capacity to the high capacity, there will be an excess air condition for a while. As a result, flammability deteriorates.

The present invention aims to solve such technical problems and provide a forced air supply/exhaust type combustion apparatus that prevents deterioration of combustibility due to the influence of air supply temperature.

(Means for Solving the Problems) In order to achieve the above object, the forced air supply and exhaust combustion apparatus of the present invention has the following configuration.

That is, in a device in which the exhaust pipe and the supply pipe are formed into a double pipe shape, and the rotation speed of the fan is controlled to a predetermined scheduled rotation speed corresponding to the combustion amount, the rotation speed of the fan is set to the predetermined rotation speed. A $4 control means is provided for increasing the rotation speed stepwise from a lower rotation speed at predetermined time intervals and finally controlling the rotation speed to the predetermined speed.

(Example) Fig. 2 is a schematic diagram of the supply/exhaust part of a forced air supply/exhaust type combustion apparatus showing an example of the present invention, where l is an exterior, 2 is a front cover, 3 is a heat exchanger, and 4 is a burner. It is. Reference numeral 5 denotes an exhaust manifold fixed above the heat exchanger 3, 6 an exhaust manifold connected to the exhaust manifold 5, a feed pipe 7 concentrically provided outside the exhaust manifold 6, and a double pipe-like structure. It forms the air supply and exhaust air 1'J18. 9 is a fan for supplying air; 10 is a duct connecting the supply cylinder 7 and the suction port of the fan 9;

FIG. 3 is a fuel supply system diagram of the burner 4. The burner 4 is divided into a plurality of combustion tube groups 41, 42, 43, and equipped with electromagnetic valves 11, 12 for switching capacity and a proportional 'M control valve 13. ing. 14 is a former solenoid valve.

FIG. 4 is a water flow system diagram including the heat exchanger 3, and the inlet channel of the heat exchanger 3 is provided with a water flow sensor 15 for detecting the amount of water passing through and an inlet water temperature sensor 16 for detecting the temperature of the inlet water. A hot water temperature sensor 17 is installed in the path to detect the hot water temperature, and the set temperature is set by a hot water temperature setting device (not shown).
The required heat capacity is calculated based on the detected water inlet temperature and water flow rate, and the corrected heat amount is calculated based on the deviation between the set temperature and the outlet temperature, and these are combined to calculate the combustion IG of burner 4.
can be determined. Based on this combustion amount G, the electromagnetic valves 11 and 12 for capacity switching and the proportional control valve 13 are controlled, and furthermore, the optimal rotation speed of the fan 9 (stable combustion state) is determined in accordance with the combustion amount G. is experimentally determined in advance as the planned rotational speed, as shown in FIG.

FIG. 1 is a control block diagram of the fan 9, and 18 is a first rotation speed setting means that inputs the signal of the combustion amount G output from the combustion amount calculation means 24 and outputs the scheduled rotation speed, and 19 is described later. Clock pulse generating means 20 operates when at least one of the ignition end signal E and the capacity switching signal C is input manually; When the output pulse is input manually and the first pulse is input, the planned rotation speed is 88.
%, the next pulse input will output the set rotation speed of 92% of the planned rotation speed, and when the next pulse is input manually, the set rotation speed of 96% of the planned rotation speed will be output. , a second rotation speed setting means configured to finally output a set rotation speed equal to the scheduled rotation speed. 21
is an output selection means that outputs the set rotation speed when there is input from the second rotation speed setting means 20, and outputs the planned rotation speed when input is received only from the first rotation speed setting means 18. . Reference numeral 22 denotes a fan motor driving means that compares the rotational speed signal manually inputted from the output selection means 21 and the rotational speed of the fan 9 detected by the first rotational speed detection stage 23, and controls the voltage applied to the fan 9 at t4. .

During the ignition operation, the combustion amount calculation means 24 outputs the combustion amount signal Ge for ignition, the first rotation speed setting means 18 outputs the set rotation speed Re for ignition, and the rotation speed of the fan 9 is set for this ignition. The rotation speed Re is increased by tsm. When ignition is detected by the flame detection means (not shown), an ignition end signal E is manually inputted to the combustion amount calculation means 24 and the clock pulse generation means 19, and the combustion amount calculation means 24 calculates the combustion amount and generates a clock pulse. Means 19 is activated.

Here, if the combustion amount output by the combustion amount calculation means 24 is Gn, the first rotation speed setting hand! 118 outputs the scheduled rotation speed Rn corresponding to the combustion tGn, but since the second rotation speed setting means 20 outputs the set rotation speed according to the output pulse from the clock pulse generation means 19, the output selection means 2
1. The fan 9 is adjusted to the set rotation speed output by the second rotation speed setting means 20 via the fan motor driving means 22. That is, as shown in FIG. 6, when the clock pulse generating means 19 first outputs a pulse, at To, the rotation speed reaches 88% of the planned rotation speed Rn, and then at the time T when the pulse is output. At +Tz, the rotation speed is controlled to 92% and 96% of the scheduled rotation speed, respectively, and when the final pulse is output, at T, the planned rotation speed I4 is controlled to Rn.

In this way, when the supply air temperature is low at the beginning of ignition, the rotational speed is gradually increased from a lower rotation than in a stable combustion state to prevent flame lifting and the like.

In addition, in this embodiment, the number of combustion tubes in the burner 4 is set to 4 in the combustion tube group.
The ability to burn only 2 is small, the ability to open the solenoid valve 11 and burn the combustion tube group 41 is medium, and the ability to open the solenoid valve 12 and burn all the combustion tube groups 41, 42, 43 is large. The capacity switching signal C is manually input to the clock pulse generating means 19 when the capacity is switched from low or medium capacity to high capacity due to changes in water flow rate or set temperature.

When the capacity switching signal C is input, the clock pulse generating means 19 is activated in exactly the same way as when the ignition end signal E is input.
is activated, and the rotation speed of the fan 9 is controlled according to the set rotation speed output by the second rotation speed setting means 20.

(Effects of the Invention) The forced air supply and exhaust type combustion apparatus of the present invention has the following excellent effects. In other words, it is possible to easily and effectively prevent the inconvenience of deterioration of the combustion state such as flame lifting caused by excess air due to low supply air temperature during the initial stage of ignition of the burner.

[Brief explanation of the drawing]

Fig. 1 is a control block diagram of a fan showing an embodiment of the present invention, Fig. 2 is a schematic diagram of the supply/discharge part of the same embodiment, Fig. 3 is a fuel supply system diagram of a burner of the same embodiment, and Fig. 4 is a diagram of the fuel supply system of the burner of the same embodiment. Water flow system diagram of the same example,
FIG. 5 is a diagram showing the relationship between the combustion amount and the planned rotational speed in the same example, and FIG. 6 is a characteristic diagram for controlling the rotational speed M in the same example. (4) Burner (6) Exhaust pipe (7) Supply cylinder (8) Supply and exhaust pipe (9) Fan (10) Duct

Claims (1)

[Claims] In a device in which the exhaust pipe and the supply pipe are formed into a double pipe shape, and the fan rotation speed is controlled to a predetermined scheduled rotation speed corresponding to the combustion amount, the fan rotation speed is lower than the scheduled rotation speed. 1. A forced intake/exhaust type combustion apparatus characterized in that a control means is provided for increasing the rotational speed stepwise at predetermined time intervals and finally controlling the rotational speed to the predetermined rotational speed.