JP2000205554A - Spray combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce emission of exhaust gas significantly from early stage of ignition by increasing the fuel ejection frequency of a solenoid fuel spray valve during low combustion operation in the early stage of ignition and decreasing the fuel ejection frequency of the solenoid fuel spray valve when combustion is settled and high combustion operation is started. SOLUTION: A control means 11 for controlling an injector 1, a spark plug 3 and an air pump 4 and controlling the valve open frequency of the injector 1 depending on the measurement of an oxygen sensor 10 operates a combustor at low combustion quantity in the early stage of combustion after starting fuel ejection and ignition before settling combustion. After combustion is settled, the combustor is operated at high combustion quantity and the fuel ejection frequency of a solenoid fuel spray valve is set at a high value when the combustion quantity is low and set at a low value when the combustion quantity is high. More specifically, the injector 1, spark plug 3 and air pump 4 are controlled in the early stage of combustion. Alternatively, combustion quantity may be increased gradually after settling combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray combustion device for spraying and burning liquid fuel.

[0002]

2. Description of the Related Art As a technique for reducing exhaust emissions (HC, CO), a technique disclosed in Japanese Patent Application Laid-Open No. 10-220711 is known. This technique is to generate a swirling flow by combustion air in a combustion cylinder, and to improve the mixing property between spray fuel and combustion air.

[0003]

However, even with the technique disclosed in the above-mentioned publication, no remarkable reduction in exhaust emission was obtained in the early stage of ignition at a low combustion environment temperature.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a spray combustion device capable of remarkably reducing exhaust emission from an early stage of ignition.

[0005]

Means for Solving the Problems In the initial stage of starting combustion, ignition by ignition is performed in a state where the combustion environment temperature is low, so that until the combustion environment temperature rises and combustion becomes stable. The combustion is performed with a low combustion amount. By adopting the first aspect, the fuel injection frequency of the electromagnetic fuel injection valve is set high at the time of the low combustion operation at the beginning of ignition. As a result, the fuel particles sprayed from the electromagnetic fuel injection valve become finer, the ignition delay time at the time of ignition can be shortened, and the exhaust emission at the time of ignition can be reduced. If combustion is stabilized and combustion is performed at a high combustion rate, low emission emissions can be achieved by existing technology without setting the fuel injection frequency high, so the fuel injection frequency of the electromagnetic fuel injection valve is set low. You. Thus, the durability of the electromagnetic fuel injection valve can be improved.

When the elapsed time from the start of fuel injection is short, the fuel injection frequency of the electromagnetic fuel injection valve is set high. As a result, the fuel particles sprayed from the electromagnetic fuel injection valve become finer, the ignition delay time at the time of ignition can be shortened, and the exhaust emission at the time of ignition can be reduced. If the elapsed time from the start of fuel injection is long, combustion is stabilized, so low emission emissions can be achieved with existing technologies without setting the fuel injection frequency high, and the fuel injection frequency of the electromagnetic fuel injection valve is low. Is set. Thus, the durability of the electromagnetic fuel injection valve can be improved.

[Claim 3] In the initial stage of the start of combustion, the fuel is not ignited even during ignition, or is not completely burned even if ignited. As a result, the oxygen concentration is high. It is in. For this reason, when the measured oxygen concentration is high,
The fuel injection frequency of the electromagnetic fuel injection valve is set to a high value in an unignited state during ignition or in an early stage of ignition. As a result, the fuel particles sprayed from the electromagnetic fuel injection valve become finer, the ignition delay time at the time of ignition can be shortened, and the exhaust emission at the time of ignition can be reduced. When combustion stabilizes, low emission emissions can be achieved by existing technology without setting the fuel injection frequency high, so when the measured oxygen concentration is low due to combustion stabilization, the fuel injection frequency of the electromagnetic fuel injection valve can be reduced. Is set low. Thus, the durability of the electromagnetic fuel injection valve can be improved.

In the initial stage of starting combustion, the temperature measured by the temperature measuring means is low because the ignition is in the unignited state even during ignition, or the ignition is early even if ignited. For this reason, when the temperature measured by the temperature measuring means is low, it is in the unignited state during ignition or in the initial stage of ignition, and the fuel injection frequency of the electromagnetic fuel injection valve is set high. As a result, the fuel particles sprayed from the electromagnetic fuel injection valve become finer, the ignition delay time at the time of ignition can be shortened, and the exhaust emission at the time of ignition can be reduced. If combustion stabilizes, low emission emissions can be achieved by existing technology without setting the fuel injection frequency high, so when the temperature measured by the temperature measurement means is high due to combustion stabilization, the electromagnetic fuel injection The fuel injection frequency of the valve is set low. Thus, the durability of the electromagnetic fuel injection valve can be improved.

[Means of Claim 5] In the initial stage of starting combustion, the luminous intensity measured by the light sensing means is low because the ignition is not performed even during ignition. For this reason, when the measured luminous intensity is low, it is in an unignited state during ignition, and the fuel injection frequency of the electromagnetic fuel injection valve is set high. As a result, the fuel particles sprayed from the electromagnetic fuel injection valve become finer, the ignition delay time at the time of ignition can be shortened, and the exhaust emission at the time of ignition can be reduced. When combustion stabilizes,
Even if the fuel injection frequency is not set high, the emission emission can be reduced by the existing technology, so that when the combustion is started and the luminous intensity measured by the light sensing means is high, the fuel injection frequency of the electromagnetic fuel injection valve is increased. Set lower. Thus, the durability of the electromagnetic fuel injection valve can be improved.

[0010] If the outside air temperature is low, the temperature of the sent combustion air is low, so that emission is likely to occur. In such a low outside air temperature, the fuel injection frequency of the electromagnetic fuel injection valve is set high, so that the fuel particles sprayed from the electromagnetic fuel injection valve become finer, and the ignition delay time at the time of ignition can be reduced. Thus, exhaust emissions during ignition can be reduced. If the outside air temperature is high, the temperature of the sent combustion air is high, so that the emission hardly occurs. In such a state where the outside air temperature is high, the fuel injection frequency of the electromagnetic fuel injection valve is set low, so that the durability of the electromagnetic fuel injection valve can be improved.

According to a seventh aspect of the present invention, the porous member is disposed in a portion where the fuel injected from the electromagnetic fuel injection valve reaches, so that the fuel reaching the porous member during steady combustion is evaporated. And burn. Thereby, even if the combustion load factor is high, excess fuel can be evaporated and burned, and as a result, emission can be reduced.

The ignition section of the ignition means is disposed inside or outside a predetermined injection angle of the fuel injected from the electromagnetic fuel injection valve. That is, since the igniter is disposed at a position deviating from the main flow of the fuel injected from the electromagnetic fuel injection valve, the igniter ignites the fine fuel in the combustion air, and the ignitability is improved. Therefore, the ignition time can be shortened, and the emission at the time of ignition can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described using a plurality of examples and modifications. [First Embodiment] An outline of a spray combustion apparatus will be described with reference to FIG. The spray combustion device shown in this embodiment is used for circulating water heating means in an automotive air conditioner, and is provided to burn light oil. This spray combustion device is an electromagnetic fuel injection valve (hereinafter, referred to as a fuel injection valve) that sprays liquid fuel supplied at a high pressure from a fuel tank 1A by a fuel pump 1B.
An injector 1) is provided to burn fuel sprayed from the injector 1. The injector 1 has a plurality of injection holes that can inject fuel at a certain angle (30 to 50 degrees) from a central axis. The part where the fuel injected from the injector 1 reaches
A spark plug 3 (corresponding to ignition means) is attached so that A (corresponding to ignition part) is arranged.

Air pump 4 (blower for supplying combustion air)
A flange 6 provided with a combustion air inlet 5 connected to the housing 6 is a semi-container body, which abuts with an opening edge of a housing 7 having a circulating water passage 7A therein, and a central portion of the combustion air inlet 5 of the flange 6. Is fixed to the injector 1. Further, a cylindrical combustion cylinder 2 and a combustion auxiliary cylinder 8 having a diameter slightly smaller than that of the combustion cylinder 2 are fixed to the flange 6. An air hole 8A is provided in a side wall of the combustion auxiliary cylinder 8, and is provided so as to flow combustion air both inside (on the side where fuel is injected) and outside the combustion auxiliary cylinder 8.

The circulating water passage 7A of the housing 7 communicates with a circulating water inlet 7B and a circulating water outlet 7C provided on the wall surface of the housing 7. Further, the housing 7 is provided with an exhaust port 7D, and exhaust gas generated in the combustion tube 2 is guided to the exhaust port 7D through the outside of the combustion tube 2, and at that time, the circulating water in the housing 7 is The circulating water in the passage 7A is heated.

A wick 9 (corresponding to a porous member) made of foamed metal is arranged inside the above-described combustion auxiliary cylinder 8 at a portion where the fuel injected from the injector 1 reaches. With such a configuration, the injected fuel is held in the wick 9, vaporized, and evaporative combustion becomes possible. This evaporative combustion has the advantage that clean combustion can be performed even when the combustion load factor is high during steady-state combustion, but it takes time to ignite because the environmental temperature in the combustion chamber is low and evaporation is difficult. There is. However, if the combustion injection frequency is increased only at the time of ignition, the spray particle diameter becomes small and spray combustion becomes possible, so that instant ignition becomes possible. FIG. 2 shows the measurement result of the volume ratio of the fine spray by the fuel injection frequency. FIG. 3 is a schematic diagram of a high-frequency spray state and a low-frequency spray state.

An O 2 sensor 10 for measuring the oxygen concentration in the exhaust is provided on the housing 7 near the exhaust outlet of the combustion tube 2.
(Corresponding to oxygen concentration measuring means). The injector 1, the spark plug 3, and the air pump 4 are controlled by the control means 11, and control the injector valve opening frequency in accordance with the value measured by the O2 sensor 10. Instead of the O2 sensor 10, a temperature sensor (corresponding to a temperature measuring means) for measuring the temperature inside the combustion cylinder 2 and an optical sensor (corresponding to a light sensing means) for measuring the luminous intensity inside the combustion cylinder 2 are provided. The ignition may be monitored or the ignition state may be assumed based on the lapse of time from the start of fuel injection (the flow chart in FIG. 6 shows the control based on the lapse of time).

As shown in the lower graph of FIG. 4, the control means 11 sets a low combustion amount at the beginning of combustion from the start of fuel injection to a stable combustion after ignition, and a high combustion amount after the combustion is stabilized. As shown in the upper graph of FIG. 4, when the combustion amount is low, the fuel injection frequency of the electromagnetic fuel injection valve is set high, and when the combustion amount is high, the fuel injection frequency of the electromagnetic fuel injection valve is set low. It is provided as follows. Specifically, the injector 1, the spark plug 3, and the air pump 4 are controlled as shown in FIG. FIG. 6 shows a control flowchart at this time. As shown in FIG. 7, when the combustion is stabilized and the amount of combustion is increased,
The combustion amount may be gradually increased.

The injector 1 of this embodiment employs a well-known structure shown in FIG. Further, when the combustion is stabilized, a swirling flow by the combustion air is generated in the combustion cylinder 2 to reduce the exhaust emission without setting the fuel injection frequency high, and the mixing of the spray fuel and the combustion air is performed. Means to improve the performance. This means
As shown in FIGS. 9 and 10, a swirl generating ring 12 is attached to the combustion air inlet 5 of the flange 6, and the ring 12 is formed with a plurality of oblique holes 12 A for generating swirling air. The combustion air inlet 5 is connected to the air pump 4 via a combustion air supply passage 13, and the injector 1 is sealed by an O-ring 14.

Next, the operation will be described. When an operation switch (not shown) is turned on, the control means 11 operates the injector 1, the spark plug 3, and the air pump 4, and supplies a fuel injection amount and a combustion air amount corresponding to a capacity smaller than the maximum combustion capacity. After a set time has elapsed, the combustion capacity is increased instantaneously or gradually to the maximum capacity. The injector valve opening frequency when the fuel supply amount is small in the early stage of the combustion start is set higher than in the steady state, and the valve opening frequency is set lower after the set time has elapsed. When the operation switch is turned off, the control means 11 stops the injector 1 and the spark plug 3 and also stops the air pump 4 after a lapse of a set time. However, the spark plug 3 may be provided so as to stop after a predetermined time has elapsed since the operation switch was turned on (see FIG. 7).

The first embodiment has the following features.
Nos. 4, 5, 7, and 8 are provided, and have the functions and effects described in the above section [Means for Solving the Problems].

[Second Embodiment] A second embodiment will be described with reference to FIG. The fuel injected from the injector 1 forms a main stream 1C in a normal direction at a certain angle (30 to 50 degrees). In the second embodiment, the spark plug 3 is attached so that the spark portion 3A is arranged inside the main stream 1C. This adopts the ninth aspect, and has the same effect as that of the ninth aspect of the invention.

The spray combustion apparatus of the second embodiment is used for warming up vehicle parts, and has a combustion gas outlet pipe 15 for blowing hot air at the bottom of the combustion cylinder 2. Further, in the second embodiment, the valve opening frequency of the injector 1 is controlled according to a measurement value from an outside air temperature sensor (not shown), and the control unit 11 increases the fuel injection frequency when the outside air temperature is low, Conversely, when the outside air temperature is high, the fuel injection frequency is set low. This adopts claim 6 and achieves the operation and effect described in claim 6 in the above-mentioned [Means for Solving the Problems].

Third Embodiment A third embodiment will be described with reference to FIG. In the third embodiment, the spark plug 3 is attached so that the spark portion 3A of the spark plug 3 is arranged outside the main flow 1C of the fuel injected from the injector 1. This adopts the tenth aspect, and achieves the operation and effect as described in the tenth aspect of the above-described [Means for Solving the Problems].

In the third embodiment, a temperature sensor 16 is mounted on the outer wall of the combustion tube 2 to measure the temperature inside the combustion tube 2. The control means 11 controls the valve opening frequency of the injector 1 according to the measurement value from the temperature sensor 16, and increases the fuel injection frequency when the combustion temperature is low, and conversely when the combustion temperature is high. Set the fuel injection frequency low. This adopts claim 4 and achieves the operation and effect described in claim 4 in the above-mentioned [Means for Solving the Problems]. In addition, instead of the temperature sensor 16 shown in this embodiment, the same control may be performed using a thermocouple or an optical sensor for measuring the luminous intensity in the combustion tube 2.

[Modification] In the above embodiment, an example is shown in which the present invention is applied to a circulating water heating means in a vehicle air conditioner and a warming means for a vehicle part. The present invention may be applied to the above-described combustion device. In addition, kerosene or alcohols may be used as fuel in addition to light oil. In the above embodiment, the spark plug 3 has been described as an example of the ignition means, but a glow plug may be used.

[Brief description of the drawings]

FIG. 1 is a schematic view of a spray combustion device (first embodiment).

FIG. 2 is a graph showing a relationship between frequency and volume ratio (first embodiment).

FIG. 3 is a schematic diagram of a high-frequency spray state and a low-frequency spray state (first embodiment).

FIG. 4 is a time chart showing a relationship between a combustion amount and a valve opening frequency (first embodiment).

FIG. 5 is a time chart at the start of combustion (first embodiment).

FIG. 6 is a flowchart showing control at the start of combustion (first embodiment).

FIG. 7 is a time chart at the start of combustion (first embodiment).

FIG. 8 is a sectional view of the injector (first embodiment).

FIG. 9 is a schematic sectional view of a swirl generating means (first embodiment).

FIG. 10 is a plan view and a cross-sectional view of a swirl generating ring (first embodiment).

FIG. 11 is a schematic view of a spray combustion device (second embodiment).

FIG. 12 is a schematic view of a spray combustion device (third embodiment).

[Explanation of symbols]

 Reference Signs List 1 injector (electromagnetic fuel injection valve) 2 combustion cylinder 3 spark plug (ignition means) 3A spark part (ignition part) 9 wick (porous member) 10 O2 sensor (oxygen concentration measuring means) 11 control means 16 temperature sensor (temperature Measuring means)

Continued on the front page (72) Inventor Akihisa Kokubo 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Co., Ltd. (Reference) 3K055 AA01 AB04 AB05 AB06 BA01 BA02 BB07 BD01 3K068 FB01 FC06 GA02 HA03 HA07 JA06

Claims (10)

[Claims] 1. A spray combustion device comprising an electromagnetic fuel injection valve for spraying a liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve. At the beginning of the combustion start until the combustion is stabilized, the combustion amount is set to be low, and after the combustion is stabilized, the combustion amount is set to be high.When the combustion amount is low, the fuel injection frequency of the electromagnetic fuel injection valve is set to be high. A spray combustion apparatus characterized by using control means for setting a low fuel injection frequency of the electromagnetic fuel injection valve. 2. A spray combustion device comprising an electromagnetic fuel injection valve for spraying liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve, wherein the time elapsed from the start of fuel injection is short. A control means for setting the fuel injection frequency of the electromagnetic fuel injection valve high, and setting the fuel injection frequency of the electromagnetic fuel injection valve low when the elapsed time from the start of fuel injection is long. Spray combustion equipment. 3. An oxygen concentration measuring device comprising an electromagnetic fuel injection valve for spraying liquid fuel supplied at a high pressure, wherein an oxygen concentration in combustion is measured in a spray combustion device for burning fuel sprayed from the fuel injection valve. Means is used, when the oxygen concentration measured by the oxygen concentration measuring means is high, the fuel injection frequency of the electromagnetic fuel injection valve is set high, and when the oxygen concentration measured by the oxygen concentration measuring means is low, A spray combustion apparatus characterized by using control means for setting a low fuel injection frequency of the electromagnetic fuel injection valve. 4. A spray combustion device comprising an electromagnetic fuel injection valve for spraying a liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve, wherein a temperature measuring means for measuring a combustion temperature is used. When the temperature measured by the temperature measuring means is low, the fuel injection frequency of the electromagnetic fuel injection valve is set high, and when the temperature measured by the temperature measuring means is high, the fuel injection frequency of the electromagnetic fuel injection valve is increased. A spray combustion device characterized by using a control means for setting a low value. 5. A spray combustion device comprising an electromagnetic fuel injection valve for spraying liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve, a light sensing device for measuring the light intensity in the combustion chamber. When the light intensity measured by the light sensing means is low, the fuel injection frequency of the electromagnetic fuel injection valve is set high, and when the light intensity measured by the light sensing means is high, the electromagnetic fuel injection valve is used. And a control means for setting a low fuel injection frequency. 6. A spray combustion device comprising an electromagnetic fuel injection valve for spraying liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve, wherein an outside air temperature measuring means for measuring an outside air temperature is provided. The fuel injection frequency of the electromagnetic fuel injection valve is set to be high when the measurement temperature of the outside air temperature measurement unit is low, and the fuel of the electromagnetic fuel injection valve is set when the measurement temperature of the outside air temperature measurement unit is high. A spray combustion device characterized by using control means for setting the injection frequency low. 7. A spray combustion device comprising an electromagnetic fuel injection valve for spraying a liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve, wherein the fuel is injected from the electromagnetic fuel injection valve. A spray combustion device, wherein a porous member is disposed in a portion where fuel reaches. 8. The spray combustion apparatus according to claim 7, wherein a passage through which combustion air flows is provided on an inner surface of the porous member on a combustion side and an outer surface on a non-combustion side of the porous member. . 9. A spray combustion device comprising an electromagnetic fuel injection valve for spraying a liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve. And an ignition unit of ignition means for igniting the fuel is arranged inside a predetermined injection angle of the fuel injected from the electromagnetic fuel injection valve. Combustion equipment. 10. A spray combustion device comprising an electromagnetic fuel injection valve for spraying a liquid fuel supplied at a high pressure and burning the fuel sprayed from the fuel injection valve. And an ignition unit of ignition means for igniting the fuel is provided outside a predetermined injection angle of the fuel injected from the electromagnetic fuel injection valve. Combustion equipment.