JPH10306923A - Liquid fuel combusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an unburned gas from risting by providing a control device wherein the mixing rate of a fuel is forcibly increased, and at the same time, the jetting speed of a mixed gas from a flame forming part is suppressed, and the amount of air for combustion is increased so that the mixing rate of the fuel may be set at a mixing rate at the time of a normal combustion after a specified period of time has passed. SOLUTION: After waiting a fixed period of time as the specified period of time when the amount of air for combustion is made smaller than a normal time since a blower 28 for convection is operated as the starting point, the revolution number of a blower 27 for combustion is raised to a second revolution number which is larger than a first revolution number but smaller than a revolution number corresponding with the feeding amount of an electromagnetic pump 26, and the blower 27 for combustion is continuously operated only for a specified period of time. For this reason, the mixing rate of a fuel is forcibly fixed to a higher side than normal only for a specified period of time so that air based on the fuel being fed to a burner may become less, and the generation of an unburned gas during this period is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid fuel combustion apparatus such as a petroleum fan heater or a forced supply / exhaust type hot air heater for vaporizing and burning liquid fuel in a vaporizer.
The present invention relates to improvement of ignition stability during an ignition operation.

[0002]

2. Description of the Related Art Conventionally, in this type of liquid fuel combustion apparatus, unburned gas (hereinafter referred to as unburned gas) of a mixed gas is generated even during an ignition operation, and this unburned gas is used in the liquid fuel combustion apparatus. It is clear that it is released outside the aircraft and smells. In addition, it takes a little time (less than one second) from the time when the igniter as an ignition device sparks at the time of ignition to generate a fire for ignition to the time when the fire is completed in the entire burner portion as the flame forming portion of the burner. ). It is found that the flame rises at the time of completion of this fire transfer, but at this time, as a phenomenon indicating the generation of unburned gas, the flame flickers in an unstable state. Further, it has been found that, even when air is blown from the convection blower during the ignition operation, the ignitability is deteriorated such that the flame is disturbed or the fire is hardly transferred, and unburned gas is easily generated.

[0003] The amount of unburned gas here is determined by the structure of the combustion section of the liquid fuel combustion apparatus, the control sequence of the ignition operation, and more specifically, the structure of the burner head corresponding to the flame forming section.
The temperature of the burner head and vaporizer, the mixture ratio of the mixed gas (air-fuel ratio), and the velocity of the mixed gas ejected from the flame forming section (speed)
-It may be changed by various factors such as the amount of combustion. Among these factors, it was found that the influence of the mixing ratio (air-fuel ratio) of the mixed gas and the jet velocity of the mixed gas from the flame forming portion was particularly large.

Therefore, in order to reduce the time required for the flame forming portion to complete the fire transfer at the time of ignition and to reduce the generation of unburned gas as much as possible, the convection blower is stopped at the beginning of the ignition operation, and the mixing is stopped. The mixture ratio of the gas (that is, the air-fuel ratio) is forcibly fixed to the side where the amount of air is small so as to increase the mixture ratio of the mixture gas, and at the same time, appropriately suppress the ejection speed of the mixture gas from the flame forming portion. A liquid fuel combustion device has been devised.

[0005] With such a configuration, a fire transfer in the flame forming portion can be performed in a short time and reliably, and as a result, the amount of unburned gas generated is reduced, and the odor at the time of ignition can be reduced.

[0006]

However, in such a liquid fuel combustion apparatus, the liquid fuel stored in the fuel supply pipe for guiding the liquid fuel to the vaporizer can be obtained by leaving the apparatus for a long time. The fuel is returned to the fuel tank side under the influence of the atmospheric pressure. As a result, a slow leak phenomenon occurs in which an empty portion where no liquid fuel exists is formed from the tip of the fuel discharge nozzle to the fuel supply pipe connected thereto.

When the ignition operation is started in the state where the slow leak has occurred, even if the electromagnetic pump is driven, the air in the empty portion is initially pushed out from the fuel discharge nozzle even when the electromagnetic pump is driven. A time lag of several seconds (usually 3 to 5 seconds) occurs before the air is sprayed. During this time, the air-fuel ratio of the mixed gas drops extremely or the air-fuel ratio becomes unstable, and the above-mentioned forced fixing control of the air-fuel ratio is performed. Does not work,
There was a problem that unburned gas was generated at the time of ignition.

Further, if the ignition timing is delayed due to the slow leak, it is affected by the air from the convection blower, and the ignition performance is further deteriorated.

An object of the present invention is to provide a liquid fuel combustion apparatus which can solve the above-mentioned drawbacks, can ignite reliably even after being left for a long time, and can more reliably prevent the generation of unburned gas. is there.

[0010]

That is, according to the present invention, liquid fuel supplied by a fuel supply device is vaporized by a vaporizer, and the vaporized gas is combined with combustion air from a combustion blower. In a liquid fuel combustion device that mixes and ignites this mixed gas with an ignition device and burns it in a flame forming portion, after the fuel supply device is activated, the combustion is performed for a predetermined time after the slow leak of the liquid fuel is released. The amount of air for use is made smaller than usual to forcibly increase the mixing ratio of the fuel, and at the same time, the injection speed of the mixed gas from the flame forming section is suppressed. A control device for increasing the amount of combustion air is provided in order to set the mixture ratio during normal combustion.

Further, in the present invention, the control device operates the convection blower with a delay for a predetermined time after the slow leak of the liquid fuel is released after the operation of the fuel supply device. It is characterized by the following.

Further, according to the present invention, the slow leak of the liquid fuel is detected by a liquid fuel detecting means provided at a downstream end of a fuel supply pipe.

According to a fourth aspect of the present invention, the liquid fuel detecting means comprises a flow sensor or an optical sensor for detecting the presence or absence of liquid fuel in the fuel supply pipe.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic perspective view showing an entire configuration of an oil fan heater as a liquid fuel combustion device showing one embodiment of the present invention, FIG. 2 is a sectional view showing the internal structure of the combustion device, FIG. FIG. 4 is a block circuit diagram of a control device centering on a control unit for controlling the liquid fuel supply device, the combustion blower, and the convection blower. FIG. 4 is a flowchart schematically illustrating a control operation of the control unit.
FIG. 5 is a main flowchart of the present invention showing an outline of the ignition operation sequence of FIG. 4, and FIG. 6 is a time chart showing a general change of signals in the ignition operation sequence of FIG.

In FIG. 1, reference numeral 1 denotes an outer case constituting the main body of the oil fan heater H, and 2 denotes an outlet for blowing out hot air. There are a blower for combustion and a blower for convection.

As shown in FIG. 2, the combustion chamber referred to here includes a fuel tank 35 and a carburetor 31 and a burner head 32 as a flame forming portion disposed above the carburetor 31 (these are generally referred to as a burner or a burner). An electromagnetic pump 26 for supplying fuel to a combustion section) and a fuel supply pipe 33;
A liquid fuel supply device including a fuel discharge nozzle 34 at the tip thereof, an ignition plug 25 (igniter) as an ignition device, and a flame as an ignition and flame detection device for detecting the state of a flame formed in the burner head 32 Sensor 2
There is disposed a combustion device composed of a heater 0 and a vaporization heater 24 incorporated in the vaporizer 31.

Further, a flow sensor 29 as a liquid fuel detecting means for detecting a slow leak of liquid fuel described later is provided on a portion of the fuel supply pipe 33 near the fuel discharge nozzle 34.
(Or an optical sensor).

Reference numeral 3 denotes an openable and closable lid for inserting and removing a cartridge tank 36 which is detachably set with respect to the fuel tank 35 shown in FIG. 2, and 4 denotes an operation of the oil fan heater H by control means to be described later. An operation panel as an operation unit in which operation means such as a switch for giving an instruction and display means such as a liquid crystal are arranged, and is provided on the upper surface of the outer case 1.

Here, on the lower part of the back of the oil fan heater H, an electric device such as a control device S, a combustion device, a combustion blower, and a convection blower mounted on an operation board or a control board disposed directly below the operation panel 4. A power cord for supplying power to parts is provided. If the plug of the power cord is inserted into an outlet, power is supplied to at least the control device S, and the operation of inserting the plug into the outlet Is referred to as power-on to distinguish it from the operation switch-on operation.

Next, with reference to FIG. 3, a schematic configuration of a control device S centering on the control device 11 for controlling the ignition device, the liquid fuel supply device, the combustion fan and the convection fan will be described.

S is a control device centered on the control means 11 which is a main component of the present invention. The control means 11 is a microcomputer (hereinafter simply referred to as a microcomputer) having a timer and a ROM or a RAM as a storage means. It is configured. The control means 11 outputs a control signal for controlling the operation of various loads based on the input signal.
Reference numeral 2 denotes an EEPROM connected to the control unit 11 via a signal line as a writable storage unit. In addition,
In FIG. 3, the EEPROM is expressed as if it were separate from the control means 11, but this is not a limitation and the EEPROM may be incorporated in the microcomputer.

Various switches 13 to 18 provided on the operation panel 4 and various sensors 19 to 23 and 29 provided at appropriate positions are connected to the input side of the control means 11, and the output side of the control means 11 is connected to the output side of the control means 11. Is a vaporization heater 2 built in an electric component, that is, a burner 31 (specifically, a vaporizer).
4. an ignition plug (igniter) 25 as an ignition device;
An electromagnetic pump 26 constituting a part of a fuel supply device for supplying fuel from a fuel tank 35 to a burner (combustion unit);
A combustion blower 27 for supplying combustion air to the combustion section, and a convection blower 28 for sucking outside air into the outer case 1 and exchanging heat with combustion gas generated in the combustion chamber and supplying it to the outlet 2.
Is connected.

Various switches connected to the input side of the control means 11 include an operation on switch 13 for instructing the start of operation of the oil fan heater H and extension of the combustion time, an operation off switch 14 for instructing stop of the operation, and an operation In order to shorten the ignition time at the start, the ignition switch 24 for controlling the energization of the evaporator heater 24 even during the stop to preheat the evaporator and instruct the evaporator to be in standby mode is set in the combustion air inlet. When the user cleans the filter for combustion air, the user operates the filter switch 16 to make the control means 11 recognize the end of cleaning, the automatic combustion mode in which the combustion amount changes according to the room temperature, or the combustion in the constant combustion amount. The temperature control switch 17 and the liquid crystal display unit each include a mode selection unit that selects a fixed combustion mode to perform, and a temperature setting unit that sets an arbitrary room temperature. Such as standing time and a timer operation start time, there is a time setting switch 18 for setting the time.

In this embodiment, the operation-on switch 1
For the first predetermined time in the ignition operation mode, the amount of combustion air is made smaller than that in the normal combustion operation to increase the fuel mixture ratio, and thereafter, the amount of air is gradually reduced to the normal amount. It has a control function whose ultimate purpose is to reduce odor by increasing the amount close to the amount.

The various sensors include a burner thermistor 19 provided below the burner 31 (more specifically, a vaporizer) for detecting the temperature of a burner, and a flame detection device for detecting the state of a flame formed on the burner head 32. A frame sensor 20, a rotation speed sensor 21 for detecting the rotation speed of the combustion blower 27, a liquid level sensor 22 for detecting the presence or absence of liquid fuel such as kerosene stored in the fuel tank 35 at a predetermined level or more, and a suction port (not shown) A room temperature sensor 23 for detecting the temperature of outside air (that is, room air) sucked into the outer case 1 provided near the mouth, and a fuel supply pipe 33 provided near the fuel discharge nozzle 34 for the liquid fuel stored in the pipe. There is a flow rate sensor 29 for detecting the presence or absence of a slow leak.

With the above configuration, each operation process of the control means 11 will be described with reference to FIGS.

First, in step S1, the operation switch 13 is turned on.
Is turned on, and an operation start is instructed. In step S2, the operation lamp is turned on or the operation mode text is displayed on the liquid crystal display unit. In step S3, energization of the vaporization heater (for example, sheathed heater) 24 is started. It is determined whether the temperature of the vaporizer (specifically, the burner body) is a temperature suitable for the ignition operation (for example, a temperature range of 250 to 270 ° C.), and the energization control of the vaporization heater 24 is continued until the temperature reaches the proper temperature. When the temperature reaches an appropriate temperature, a drive signal is supplied to a combustion blower (specifically, a burner motor) 27 in step S5, and the burner motor 27 starts rotating. The control means 11 determines whether or not the rotation speed of the burner motor 27 detected by the rotation speed sensor 21 has reached a predetermined rotation speed (here, a first rotation speed R1 = 1100 rpm, which will be described later) after a certain time has elapsed. It is determined (step S6). If the rotation speed does not reach the specified rotation speed R1 after the lapse of a certain time, the process proceeds to steps S14 to S17. If the rotation speed reaches the specified rotation speed R1, the ignition operation is performed in step S7, and the process proceeds to step S8. In step S9, it is determined whether ignition has occurred based on the flame current detected by the flame sensor 20, and in step S9, it is determined whether normal combustion has occurred.

If it is determined that the ignition is not performed or the combustion is not normal, the operation proceeds to steps S18 to S24. If the combustion is normal, the ignition operation (spark) of the spark plug is stopped in step S10. S1
In step 1, the energization of the vaporization heater 24 is stopped, and in step S12, an automatic change operation of the combustion amount is started to set the combustion mode based on the setting of the temperature control switch 17 or the set room temperature.

In the next step S13, it is determined based on the flame current detected by the flame sensor 20 whether or not the state of the flame at the set combustion amount is normal. The operation of S13 is repeated. If the operation is not normal, the operation proceeds to the operations of steps S26 to S30.

If it is determined in step S6 that the number of revolutions of the burner motor 27 is abnormal, in step S14 the energization of the vaporization heater 24 is stopped, and in step S15 the operation lamp is turned on or off or the operation mode text on the liquid crystal display is displayed. Is blinked, and in step S16, a signal (for example, E6) indicating the rotation speed abnormality of the burner motor 27 is displayed as the content of the abnormality to notify the abnormality. In this case, the operation does not shift to the ignition operation until the abnormality is eliminated. And step S
At 17, the user can return to step S3 through the operation of the operation-off switch 14 and the operation-on switch 13.

If it is determined in step S8 or S9 that the normal flame cannot be detected within the ignition trial period (for example, 23 seconds) (this is called an ignition error), in step S18 the energization of the vaporization heater 24 is turned on. The operation is stopped, and the operation lamp is blinked in step S19 or the operation mode text on the liquid crystal display is blinked in step S19. In step S20, an ignition error is indicated as an abnormal content (for example, E1).
Is displayed to notify the abnormality. Subsequently, the ignition operation (spark) of the ignition plug 25 is stopped in step S21, the fuel supply operation of the electromagnetic pump 26 is stopped in step S22, the convection fan 28 is turned on in step S23, and the combustion fan 27 is turned on in step S24. The drive signal is stopped to stop, and the ignition sequence ends. Then, step S2
In step 5, the user can return to step S3 through the operation of the operation-off switch 14 and the operation-on switch 13.

In step S13, the ignition is started, but the abnormality is extinguished in the course of changing the amount of combustion (this is called halfway extinguishing).
If it is determined that the condition is not satisfied, in step S26, the operation lamp is blinked or the character of the operation mode on the liquid crystal display is blinked, and in step S27, a symbol (for example, E2) indicating a fire extinguishing on the way is displayed as the content of the abnormality to indicate the abnormality. Notify.

Subsequently, in step S28, the fuel supply operation of the electromagnetic pump 26 is stopped. In step S29, the drive signal is stopped to stop the convection blower 28, and in step S30, the drive signal for stopping the combustion blower 27 is stopped. End the sequence. Then, in step S31, the operation can be returned to step S3 via the operation of the driving off switch and the driving on switch 13 by the user.

Next, the ignition operation in step S7 will be described in more detail with reference to FIG.

First, in step S71, the ignition operation (ie, spark) of the spark plug 25 is first started, and then in step S72, the electromagnetic pump 26 is turned on to supply a fuel amount specific to ignition (for example, the amount of medium fuel corresponding to medium combustion). In step S73, the flow rate sensor 29 monitors the flow rate of liquid fuel in the fuel supply pipe 33 (the presence or absence of liquid fuel). When the flow rate is detected (that is, when a slow leak has occurred, when the slow leak has been released), A is set in the timer of the microcomputer 11 for a certain period of time. It is determined whether or not a predetermined time A (for example, 2.1 seconds) as a delay time has elapsed. After a lapse of the predetermined time A, the predetermined time B is set in the timer again, and in step S75, a signal for driving the convection blower 28 to a normal rotation speed F (for example, a rotation speed 960 rpm suitable for medium combustion) is output.

At this time, since the slow leak has already been released, a predetermined amount of liquid fuel is stably sprayed from the fuel discharge nozzle. Therefore, the operation is continued in the order of starting the supply of the combustion air in a smaller amount than usual, starting the ignition spark, and starting the supply of the fuel. At the beginning of the ignition trial period in which ignition is attempted, the convection blower 28 is started.
Is stopped, so that the jet speed of the mixed gas of the fuel and the combustion air supplied to the burner head is slowed down. The influence of the wind of the blower 28 can be eliminated, thereby preventing the appropriate flow of the mixed gas to be used for ignition from being disturbed by the wind for convection and becoming unstable. (Within time A), ignition becomes easy, and the conventional ignition delay and spark (lifting of flame) phenomena are less likely to occur, and the generation of unburned gas due to the ignition delay, ignition mistake, and flame lifting is suppressed. it can.

In the next step S76, a time period starting from the time when the convection blower 28 is driven is set as a predetermined time period B (a condition B≫A, B) in which the amount of combustion air is made smaller than usual. It is determined whether or not the period is called a first mode in the ignition trial period (for example, 3 seconds), and in step S77, the system waits until time B has elapsed, and sets the rotation speed of the combustion blower 27 to the first mode. Rotation speed R1 larger than the rotation speed R1 of the
3 (this is referred to as a normal rotation speed) and a second rotation speed R2 (this is referred to as a second mode, for example, 1350r
pm), and is continuously driven for a fixed time C (for example, 25 seconds).

For this reason, the mixing ratio of the fuel is adjusted for a predetermined time B so that the amount of air becomes smaller than the fuel supplied to the burner.
Only by forcibly fixing to the higher side than normal
Initial stage of the ignition operation (the ignition trial period described above) (that is,
Since the air volume in the first mode) is suppressed, the ejection speed of the mixed gas can be made lower than that of the conventional one,
As a result, the flame in the flame forming part is not generated with a tendency to lift, but spreads over the entire flame forming part, so that the flame can be quickly generated, and the fire transfer in the flame forming part is the conventional method. The operation can be performed more reliably and in a shorter time than the operation of the ignition control, and the generation of unburned gas during this period is reduced.

After the elapse of the predetermined time B, the combustion blower 2 is used to bring the mixture ratio close to the mixture ratio during normal combustion.
7 is set to a second rotation speed R2 larger than the first rotation speed R1 and smaller than the rotation speed R3 corresponding to the supply amount to the electromagnetic pump 26 (that is, a second mode in the ignition trial period), By increasing the amount of air, it is possible to further reduce the sound when the flame formed in the flame forming portion at the time of ignition is generated with a slight amount of air.

Thereafter, it is determined in step S78 whether or not a predetermined time C has elapsed. In step S79, the rotation speed of the combustion blower 27 is set to the normal rotation speed R3 (this is set as the third mode in the ignition trial period). This is called a normal mode, for example, it is increased to 1500 rpm, and the
Move to 8.

As described above, the ignition trial period from the time when the combustion blower 27 is driven to the time when the electromagnetic pump 26 is driven to stabilize the fuel mixing ratio is defined by the first mode, the second mode, and the normal mode. The mode is shifted to each mode after the flow rate of the liquid fuel is detected by the flow rate sensor 29 (that is, the slow leak is released and the air-fuel ratio of the mixed gas is stabilized as specified). ), The generation of unburned gas due to slow leak is reliably prevented, and the deodorizing effect at the time of ignition is extremely large even when the equipment is operated after being left for a long time. .

[0042]

As described above, according to the first aspect of the present invention, after the operation of the fuel supply device, the amount of the combustion air is reduced for a predetermined time after the slow leak of the liquid fuel is released. Since the fuel mixture ratio was forcibly increased by making the fuel mixture ratio smaller than that in the normal state, and after a predetermined time, the amount of combustion air was increased so that the fuel mixture ratio became the mixture ratio during normal combustion. Even if a slow leak has occurred in the combustion operation after being left for a long period of time, a stable fuel spray can always be obtained at the beginning of the ignition operation for reducing the amount of air. As a result, the flame in the flame forming portion can be generated not to be generated in a lift-like manner but to spread throughout the flame forming portion, so that the fire transfer in the flame forming portion can be performed more reliably than the conventional ignition operation. The generation of unburned gas during this period can be more reliably prevented.

According to the present invention described in claim 2,
After the operation of the fuel supply device, by operating the convection blower with a certain delay after the liquid fuel slow leak is released, even if the start of spraying of the fuel is delayed due to the slow leak, the convective blower is activated. Since the stable fuel has been sprayed and the ignition has already been completed, the wind of the convection blower does not disturb the appropriate flow of the mixed gas by the combustion blower. (Lifting) phenomenon is less likely to occur, and the ignition delay and the generation of unburned gas due to the lifting can be suppressed.

According to the third and fourth aspects of the present invention, the liquid fuel slow leak is detected by a liquid fuel detecting means such as a flow sensor or an optical sensor installed at the downstream end of the fuel supply pipe. And the detection of the presence or absence of fuel in the pipe becomes easy and reliable, and the installation location of the liquid fuel detection means is close to the fuel discharge nozzle at the downstream end of the fuel supply pipe. The fuel spray start timing is accurate,
Since the operation start time of the fuel blower and the convection blower can be set strictly without a large margin, the ignition trial period can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an overall configuration of an oil fan heater as a liquid fuel combustion device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the internal structure of the combustion device.

FIG. 3 is a block circuit diagram of a control device mainly including control means for controlling an ignition device, a liquid fuel supply device, a combustion blower, and a convection blower.

FIG. 4 is a flowchart showing an outline of a control operation of a control unit.

FIG. 5 is a main flowchart of the present invention showing an outline of the ignition operation sequence of FIG. 4;

FIG. 6 is a time chart showing a schematic change of a signal in the ignition operation sequence of FIG. 5;

[Explanation of symbols]

 H Liquid fuel combustion device (oil fan heater) S Control device 11 Control means (microcomputer) 25 Ignition device (ignition plug) 26 Fuel supply device (electromagnetic pump) 27 Combustion blower (burner motor) 28 Convection blower (fan motor) 29 liquid fuel detecting means (flow rate sensor) 31 carburetor 33 fuel supply pipe

Continued on the front page (72) Inventor Yasuhiro Kobori 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Satoshi Hoshino 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (4)

[Claims] 1. A liquid fuel supplied by a fuel supply device is vaporized by a vaporizer, and the vaporized gas is mixed with combustion air from a combustion blower, and the mixed gas is ignited by an ignition device to be ignited by an ignition device. In the liquid fuel combustion device, the amount of the combustion air is forcibly reduced for a predetermined time after the slow leak of the liquid fuel is released after the operation of the fuel supply device, and the fuel is forcibly discharged. In addition to increasing the mixing ratio of the combustion air, suppressing the injection speed of the mixed gas from the flame forming portion, and then setting the mixing ratio of the fuel to the mixing ratio for normal combustion after a predetermined time has elapsed, the amount of combustion air A liquid fuel combustion device comprising a control device for increasing pressure. 2. The control device according to claim 1, wherein, after the operation of the fuel supply device, the control device operates the convection blower with a delay of a predetermined time after the slow leak of the liquid fuel is released. Liquid fuel combustion equipment. 3. The liquid fuel detecting device according to claim 1, wherein the liquid fuel slow leak is detected by liquid fuel detecting means provided at a downstream end of a fuel supply pipe. Liquid fuel combustion device. 4. The liquid fuel combustion apparatus according to claim 3, wherein said liquid fuel detection means comprises a flow sensor or an optical sensor for detecting the presence or absence of liquid fuel in said fuel supply pipe.