JPH02169919A - Control device for forced air blasting type combustion apparatus - Google Patents

Abstract

PURPOSE:To properly control the volume of air supplied for combustion and stabilized the combustion by detecting the pressure inside a combustion chamber and controlling an air blower on the basis of the pressure. CONSTITUTION:To correct the blasting rate of an air blower 12 in response to the blasting capacity that varies according to the length and the shape of passage of an exhaust tube 4 connected to a flue connecting port 3, a pressure sensor 17 is provided at the upper part of a combustion chamber 2 formed by a burner case 1. The rotational speed of an air blower 12 is controlled according to the detected pressure P inside the combustion chamber 2, and the necessary air for combustion is supplied according to the combustion volume Q. For example, it is determined which exhaust load previously stored verges on the state of the flue 4 of an installed gas water heater from the pressure detected at the time of pre-purge, or during combustion, and the voltage V applied to the air blower 12 then, and the rotational speed of the air blower 12 is controlled according to the determined exhaust loard.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a control device for a forced-air combustion device that supplies combustion air using a blower, and is particularly applicable to various exhaust systems that differ depending on the installation conditions of the combustion equipment. Regarding improvements to make it easier to deal with.

[Prior Art] In a forced-air combustion device in which combustion air is supplied by a blower, such as a gas water heater with a heat exchanger disposed within the combustion chamber, a control valve that controls the amount of gas depending on the type of gas used is used. The characteristics differ, and depending on the installation location, the installation method (outdoor installation, indoor installation, pipe shaft door installation, pipe shaft door installation, etc.) and exhaust method (PS installation top exhaust type, PS installation rear exhaust type, PS installation top inside door) Exhaust type, ps
Gas water heaters are available with air blowing characteristics that correspond to each installation condition.

In addition, even if the same gas water heater is installed under various conditions, changing the length of the exhaust pipe will change the combustion gas exhaust capacity, so the combustion air supplied into the combustion chamber will change accordingly. The amount changes. Therefore, in forced air combustion devices, the blowing characteristics of the blower must be changed depending on the length of each exhaust stack.

For this reason, in the past, dampers (so-called fan dampers) for changing the air volume were provided at the air supply L-J, discharge port, etc. of the blower, and the degree of opening of the °C damper was changed according to the length of the exhaust pipe.
Alternatively, the voltage range of the voltage applied to the drive motor of the blower may be switched in accordance with the length of the exhaust stack, and the amount of air blown into the combustion chamber may be changed to correspond to each exhaust stack.

[Problems to be Solved by the Invention] However, with conventional systems, proper combustion air cannot be supplied unless switching is done reliably according to the length of the exhaust stack at the time of installation. A reliable response is required, and if the user changes the exhaust air after installation, for example, the ventilation characteristics may not be changed.

In addition, even if the diameter of the exhaust stack is constant, the change in air flow caused by changing the exhaust stack is not determined solely by the length of the exhaust stack, but is also greatly affected by the shape of the exhaust stack that forms the exhaust path. Because of this, the conventional method of responding only to the length of the exhaust stack cannot adequately respond to actual changes in the amount of air blown.

In particular, in a premixed all-air combustion system with a burner placed inside the combustion chamber, if the exhaust stack is extended and the airflow capacity decreases, the supply of combustion air becomes insufficient and the air-fuel ratio is not maintained properly, resulting in poor combustion and an inability to obtain the necessary amount of heating.

An object of the present invention is to provide a control device that can appropriately control the supply amount of combustion air in a forced air combustion device, perform stable combustion, and obtain a combustion amount corresponding to the required heating amount. purpose.

[Means for Solving the Problems] The present invention provides a control device for a forced-air combustion device in which a burner is arranged in a combustion chamber and combustion air is supplied into the combustion chamber by a blower, which detects the pressure in the combustion chamber. The technical means includes a pressure detection means for controlling the air blower based on the pressure detected by the pressure detection means.

[Operation] In the present invention, a pressure detection means is provided within the combustion chamber, and the blower is controlled based on the detected pressure within the combustion chamber.

As a result, for example, when the exhaust pipe is connected and the passage resistance increases, the pressure increase in the combustion chamber due to the connection of the exhaust pipe is detected, and the passage resistance is extended to compensate for the increase. Since the control amount of the blower is changed depending on the exhaust stack, an appropriate amount of combustion air is supplied to the burner.

[Effects of the Invention] In the present invention, since the blower is controlled according to the pressure inside the combustion chamber, even when the exhaust stack is connected or extended to the combustion equipment, the appropriate combustion air corresponding to the amount of fuel supplied can be obtained. The required amount of combustion can be obtained.

Additionally, if the exhaust stack is extended to a combustion device, this will be detected by the pressure detection means, so the installer or user will need to change settings such as switching control characteristics when extending the exhaust stack. do not have.

Therefore, even if the installation circumstances change and an exhaust pipe becomes necessary, the exhaust pipe can be used as is by simply extending the exhaust pipe.

[Example] Next, a control device for a forced air combustion apparatus of the present invention will be described based on an example.

In the gas water heater schematically shown in FIG. 2, a combustor 10 has a combustion chamber 2 formed inside a combustor case 1.
A burner plate 11 is disposed on the combustion chamber, and a blower 12 for supplying combustion air is provided.

The blower 8112 includes an impeller inside the scroll casing 12a that is rotationally driven by a DC brushless motor, and when the blower 12 operates, combustion air is supplied from the scroll casing 12a to the burner case lla. The scroll casing 12a is provided with a nozzle 13 for ejecting fuel gas, and the combustor 10 is equipped with a blower 1.
All-primary air combustion is performed in which combustion is performed using only the primary air supplied by No. 2.

An exhaust pipe connection port 3 is provided above the combustor case 1,
An exhaust pipe 4 having a length according to the installation conditions of the gas water heater is connected to the exhaust pipe connection port 3, and the combustion gas is guided to the exhaust pipe 4 and discharged to the outside of the combustor case 1 from an exhaust port (not shown). Ru.

Inside the combustor case 1, near the burner plate 11,
A sparker 14 for spark discharge, a flame rod 15 for detecting flame, and a thermocouple 16 for detecting combustion temperature are provided.

The fuel pipe 20 that supplies fuel gas to the nozzle 13 includes, in order from the upstream side, a main solenoid valve 21, a main solenoid valve 22, and a governor proportional valve 23 that adjusts the downstream pressure of the fuel gas according to the current value.
, a solenoid valve 24 for cutting off fuel gas is provided, and the upstream and downstream sides of the solenoid valve 24 are communicated through a fuel pipe 20 having an orifice 25. Orifice 2
Reference numeral 5 is provided to improve throttling performance, and when the electromagnetic valve 24 is in a closed state, the amount of fuel supplied is limited by the orifice 25 instead of the nozzle 13, resulting in a small combustion amount.

The wood pipe 30 consists of a supply pipe 31 and a hot water supply pipe 31a connected to a water supply source and a hot water supply port (not shown), respectively, and a heat exchanger 32 and a bypass pipe 32a provided in communication between these. A part of the water supplied from 31 passes through the heat exchanger 32, and the rest passes through the bypass pipe 32a and is led to the hot water supply pipe 31a. A bypass valve 33 is provided at the confluence of the heat exchanger 32 and the bypass pipe 32a to adjust the ratio of water heated by the heat exchanger 32 to water directly guided through the bypass pipe 32a.

In the supply pipe 31, from the upstream side, a water flow control valve 34, a water flow sensor 35, an inlet water temperature thermistor 36, and a heat exchanger 32 are installed.
A heat exchange thermistor 37 for detecting the temperature of heated hot water is provided downstream of the hot water supply pipe 31a, and a hot water outlet temperature thermistor 38 is provided in the hot water supply pipe 31a.

The control unit fi40 is mainly a microcomputer (hereinafter referred to as "microcomputer"), and as shown in FIG.
It is composed of each functional part of the water flow control part 44, and further includes a controller 50 operated by the user and a safety circuit (not shown), each of which functions as follows.

When the water flow is detected by the water flow sensor 35, the ignition control unit 41 performs ignition control in a predetermined sequence to start combustion, and stops the combustion when the water flow stops.

Here, the blower 12 is operated in response to water flow detection by the water flow sensor 35 to perform pre-purging, and the rotational speed of the blower 12 is controlled to a predetermined slow ignition rotational speed, and after the slow ignition rotational speed is detected, the sparker 14 is operated to cause spark discharge, and both the original solenoid valve 21 and the main solenoid valve 22 are opened to ignite.

When ignition occurs due to the ignition operation, it is detected by the flame rod 15, and after a minute predetermined period of time for the flame in the combustor 10 to stabilize after the ignition is detected, the combustion amount is controlled based on the set temperature and the like.

The temperature control unit 42 receives a temperature signal obtained from the resistance value of each thermistor arranged in the water pipe 30, a pulse signal from the water amount sensor 35 generated according to the amount of water passing through the wood pipe 30, and settings by the controller 50. Based on each signal of the temperature Tset, the heat exchanger 32 determines the combustion amount Q required to heat the water to the target temperature.

Here, feedforward control # (FF control) is performed until the outlet hot water temperature 'l'out detected by the outlet hot water temperature thermistor 38 reaches a predetermined condition with respect to the set temperature TSet after the start of operation. When the outlet hot water temperature TOut falls within a range of predetermined conditions with respect to the set temperature 'rset, feedback control (FB control) is performed.

As the FF control, the set temperature by the controller 50'
rset, the incoming water temperature Tin detected by the incoming water temperature thermistor 36, the incoming water amount W detected by the water amount sensor 35, and the heat exchange rate 1/err.

QFF (Tset −Tin) xW/eff, FF
The required combustion amount QFF in the control is calculated, and the fuel 3RffiQ is determined based on the required combustion f and QFF.

In addition, as for FB control, the actual heating jlq of the combustor 10 is calculated from the outlet hot water temperature TOLIt detected by the outlet hot water temperature thermistor 38, the inlet water temperature Tin, and the inlet water amount W using q=(Tout-Tin)xW. , the combustion 1tQ is determined from the required combustion amount QFF and the heating amount q.

The combustion control section 43 controls the voltage applied to the blower 8112 according to the combustion amount Q determined by the temperature control control section 42, and controls the voltage applied to the blower 12 as detected by a rotation speed sensor (not shown) provided in the blower 1112. The voltage applied to the motor of the air blower 8112 is controlled so that the rotational speed becomes the rotational speed N corresponding to the combustion ff1Q.

Further, the current value to the governor proportional valve 23 is controlled according to the controlled rotational speed N of the blower 12, so that fuel is supplied according to the amount of air blown.

In this embodiment, in order to correct the amount of air blown by the blower 12 in accordance with the air blowing capacity that varies depending on the length and passage shape of the exhaust stack 4 connected to the exhaust stack connection port 3, the combustor case 1 is configured to A pressure sensor 17 is provided on one side of the combustion chamber 2 to control the rotational speed of the blower 12 according to the detected pressure P inside the combustion chamber 2, and the necessary combustion air is supplied according to the combustion amount Q. are being supplied.

The pressure inside the combustion chamber 2 is as shown in FIG. 3 when, for example, the same voltage Va is applied to the motor of the blower 8112.
Exhaust loads L1, L2, determined by the conditions of the exhaust passage, etc.
Different pressures P1 depending on L3, ..., Ln
, P2, P3, .
From the voltage applied to ■, it is determined which pre-stored exhaust load the exhaust stack 4 of the installed gas water heater is closest to, and according to the specified exhaust load,
The rotation speed of the air blower 1a12 is controlled.

For this purpose, as shown in FIG. 4, the rotation speed characteristics preset for each exhaust load in accordance with the combustion amount Q are stored in a ROM as a storage device as control data for the blower 12. For example, the combustion amount When Qa is given, the rotation speed data corresponding to it is read out by arithmetic processing of the microcomputer according to the type of gas used and the specified exhaust load, and the specified exhaust load L1, L2, L3, etc.・、
Depending on Ln, the rotation speed of the blower 12 changes to the rotation speed N1, N
2, N3, . . . , Nn, the voltage applied to the blower 12 is controlled.

Therefore, the necessary combustion air is always supplied into the combustion chamber 2 according to the combustion amount Q even if the exhaust load changes.

Further, the value of current applied to the governor proportional valve 23 is determined based on the detected rotational speed of the blower 12.

Here, the energizing current data of the governor proportional valve 23 corresponding to the detected rotational speed is stored in the ROM for each gas type and exhaust load, and when the detected rotational speed of the blower 12 is given, the corresponding current data is stored in the ROM. The data is read out by arithmetic processing by a microcomputer according to the type of gas used and the exhaust load, and the current value to the governor proportional valve 23 is controlled based on the data.

Therefore, even if the rotational speed of the blower 12 is the same, different current values are applied to the governor proportional valve 23 depending on the pressure inside the combustion chamber 2 detected by the pressure sensor 17, thereby corresponding to the combustion JiQ. It is possible to supply fuel that is

Furthermore, in the combustion control, an error in the air-fuel ratio is determined based on the output voltage of the thermocouple 16 that is output according to the combustion temperature, and the voltage applied to the blower 12 is corrected based on the error.
By correcting the amount of combustion air supplied, an appropriate air-fuel ratio is maintained.

Furthermore, the current value to the governor proportional valve 23 is corrected in accordance with the rotational speed of the air blower TL112 that has been changed by the correction.

Note that the exhaust load in the combustion control unit 43 is identified sequentially during combustion based on the detected pressure by a program built into the microcomputer, so that the state of the exhaust load is always grasped.

In water flow control, the water flow control unit 44 uses an inlet water temperature thermistor 3.
6, the opening degree of the bypass valve 33 and the opening degree of the water flow control valve 34 are adjusted to limit the flow of water into the heat exchanger 32 in excess of the heating capacity. Note that each opening degree is detected by a potentiometer (not shown).

The gas water heater of this embodiment having the above configuration operates as follows.

When the user sets the set temperature Tset using the controller 50 and turns on a faucet (not shown), the water supplied through the supply pipe 31 is transferred to the water layer control valve 34 and the water flow sensor 35.
The water flows into the heat exchanger 32 and the bypass pipe 32a, the amount of each outflow is adjusted by the bypass valve 33, and flows out from the hot water supply port (not shown) via the hot water supply pipe 31a. When the passage of water in the supply pipe 31 is detected by the water amount sensor 35, the blower 12 starts rotating at a controlled rotation speed.

At this time, the pressure inside the combustion chamber 2 is detected by the pressure sensor 17 to identify the exhaust load, and the rotational speed of the blower 112 is controlled to be slowly ignited to a rotational speed corresponding to the exhaust load and the type of gas.

Further, ignition control is started based on a signal from the water amount sensor 35, and spark discharge is performed in the sparker 14. At the same time, the temperature of the water (hot water) flowing out from the heat exchanger 32 is detected by the heat exchange thermistor 37, and after a predetermined period of time, the original solenoid valve 21 and the main solenoid valve 22 are opened, and the governor proportional valve 23 is opened. When a predetermined slow ignition current value corresponding to the gas type and exhaust load is applied to the nozzle 13, fuel gas corresponding to the slow ignition combustion amount is ejected from the nozzle 13, mixed with combustion air, and ignited by the sparker 14. , to ignite the fire safely and reliably.

When ignition is detected by the flame rod 15, the required combustion amount QFF for FF control is calculated based on the signals from the controller 50, each sensor, and the thermistor, and based on that, the blower 12 and governor proportional valve 23 are operated according to the exhaust load. The fuel gas is controlled according to the required combustion amount QFF.

After that, when the hot water outlet temperature Tout reaches a predetermined condition, FB control is performed based on the hot water outlet temperature TOut, and the hot water outlet temperature TO
The actual heating amount q is determined based on Ut, etc., the combustion amount Q in FB control is determined, and the blower 1
2. The governor proportional valves 23 are each controlled according to the exhaust load.

Therefore, combustion air and fuel gas according to the combustion iQ are supplied into the combustion chamber 2, so that combustion occurs reliably and the necessary amount of heating is obtained.

As described above, in the gas water heater of this embodiment, the pressure inside the combustion chamber, which varies depending on the exhaust load, is detected by the pressure sensor.
Since the blower is controlled based on this, the required combustion air is supplied.

As a result, stable combustion is achieved and the necessary amount of heating is obtained.

In addition, if the exhaust stack is extended to the combustion equipment, there is no need to change settings such as switching control characteristics.
If the installation circumstances change, simply extend or remove the exhaust stack.

In this example, a gas water heater is shown, but other combustion equipment such as a heater may also be used, and the heating source is not limited to gas.
It may also be a combustion device using oil or the like.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the functional configuration of a control device for a gas water heater according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the configuration of a gas water heater according to this embodiment, and FIG. A characteristic diagram showing the relationship between the voltage applied to the blower and the pressure inside the combustor in this example for each exhaust load. Figure 4 shows the relationship between the determined combustion lid and the rotation speed of the blower in this example. It is a characteristic diagram shown for each load. In the figure, 2... Combustion chamber, 11... Burner plate (burner), 12... Air blower, 17... Pressure sensor (pressure detection means), 40... Control device (forced air combustion device control device).

Claims (1)

[Scope of Claims] 1) In a control device for a forced-air combustion device in which a burner is disposed in a combustion chamber and combustion air is supplied into the combustion chamber by a blower, the pressure detection device detects the pressure in the combustion chamber. 1. A control device for a forced air combustion apparatus, comprising: means for controlling the blower based on the pressure detected by the pressure detecting means.