JPH03202618A - Alcoholic engine - Google Patents

Abstract

PURPOSE:To enhance the combustibility and prevent generation of uncombusted gas by providing a combustion chamber of heat insulating structure recessedly in a piston head, and furnishing the cylinder head with a flat glow plug and a fuel injection nozzle having multiple jets in such a way as capable of intruding into this combustion chamber. CONSTITUTION:At the piston head part of a piston 11 a hole 9 is formed, and in it a structural wall body 20 is fitted so as to form a combustion chamber 1 of heat insulating structure. The cylinder head 10 is fitted with a flat glow plug 3 which can intrude into the combustion chamber 1, while a fuel injection nozzle 4 alike capable of intruding into the combustion chamber 1 is arranged in the position approx. in its center and being eccentric toward the glow plug 3. This fuel injection nozzle 4 shall be in such a structure that a number of jets 17 are provided in steps at the periphery of the nozzle body 19, and thereby alcoholic fuel injected through the jets 17 is allowed to collide with the flat surface 25 of the glow plug 25. Thus gasification of the fuel can be made in good performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an alcohol engine having a combustion chamber in the piston head.

[Conventional technology]

Recently, environmental pollution caused by exhaust gas emitted from engines has become a problem, and alcohol engines have been attracting attention. In an alcohol engine, the content of carbon dioxide gas and carbide in the exhaust gas is extremely small compared to fuels such as gasoline and diesel oil. However, diesel engines that use alcohol fuel have the problem of poor ignition performance. Alcohol has a higher latent heat of vaporization than gasoline; for example, while gasoline requires 0.7% of the latent heat of vaporization of fuel, alcohol requires 5% of the latent heat of vaporization of fuel. and
This is because alcohol fuel has the property of being difficult to vaporize. Moreover, the alcohol fuel injected into the compressed air in the combustion chamber from the fuel injection nozzle vaporizes, lowering the temperature of the compressed air and the wall surface of the combustion chamber, thereby worsening ignition.

Further, in the fuel injection nozzle, a fuel injection nozzle having a two-stage nozzle hole and multiple nozzle holes is disclosed in Japanese Patent Application Laid-Open No. 53-88413, for example.
This method is disclosed in Japanese Utility Model Application Publication No. 63-201768.

Furthermore, Japanese Patent Application No. 1-1824 filed by the present applicant
No. 53 No. 2 discloses an adiabatic alcohol engine in which a red-hot body is provided in the pre-chamber. an alcohol fuel injection nozzle, an incandescent body made of a high heat capacity ceramic material disposed on the inner wall surface with which the alcohol injected from the injection nozzle collides, a sensor for detecting the operating state of the engine, and a detection value from the sensor. The controller includes a controller that controls turning off the incandescent body in response to a signal value lower than a predetermined set value.

[Problem to be solved by the invention]

By the way, alcohol fuel has a calorific value of approximately 6000 K.
cal/kg, which is about half the calorific value of light oil, so the amount of alcohol fuel injected must be greater than the amount of fuel injection of light oil. Therefore, when an engine mainly using alcohol fuel is burned in a diesel cycle, the combustion process, combustion chamber, injection system, etc. are different from normal engines due to the large heat of vaporization and small calorific value. Furthermore, in an alcohol engine that uses alcohol as fuel, combustion under partial load and combustion under high load are extremely different.

When alcohol, for example methanol fuel, is used, alcohol has a large heat of vaporization as mentioned above, so in an alcohol engine, the heat of the compressed air is taken away to vaporize the fuel, and unburned intermediate products are discharged. There are many. Therefore, it is necessary to solve the following problems in alcohol engines.

First, since vaporization energy is supplied to the atomized alcohol fuel at low temperatures such as when the engine is under partial load, the combustion chamber is insulated and the temperature of the combustion chamber wall increases quickly. However, in an adiabatic engine, during partial load such as idling, the temperature of the combustion chamber wall does not reach that high, so ignition and combustion are not good, resulting in sluggish ignition and incomplete combustion, resulting in unburned gas and other aldehyde. This means that similar intermediate products are likely to be generated, and exhaust gas with a strong pungent odor is emitted. In particular, since alcohol fuel has a high latent heat for vaporization, the wall surface of the combustion chamber is not in a high temperature state when the engine is running at low speed and under low load, so the wall surface absorbs vaporization heat from the fuel and promotes vaporization. This makes it difficult to successfully vaporize the air-fuel mixture.

As a result, combustion becomes incomplete, and the phenomenon of unburned gas generation becomes significant.

Furthermore, at high temperatures such as when the engine is under full load, the combustion chamber wall is cooled with alcohol fuel so that the temperature of the combustion chamber does not rise too high. However, in an adiabatic engine, when the load is high, the walls of the combustion chamber become hot, so ignition and combustion of the fuel is carried out well, but if the temperature of the combustion chamber becomes too high, the intake efficiency decreases or abnormal ignition combustion occurs. or

On the other hand, if methanol is used as fuel, the combustion temperature is low, so there is less NOx emission and no smoke emission.
COt emissions are reduced by half compared to petroleum fuel, making it ideal as a low-pollution engine. Therefore,
Among the above characteristics, solving the above problems is important for the development of methanol engines.

The purpose of this invention is to solve the above problems,
A combustion chamber structure disposed in the throat hole of the piston so that the combustion chamber is insulated and the temperature of the combustion chamber wall increases quickly in order to supply sufficient vaporization energy to the alcohol fuel sprayed from the fuel injection nozzle. The inner wall member is made of a thin ceramic material, and the outer surface of the inner wall member is covered with a heat insulating material, so that the temperature of the combustion chamber can be increased in a short period of time. In order to accelerate the vaporization of the alcohol fuel, a heat-resistant ceramic fuel injection nozzle and a flat glow plug are placed in the center of the combustion chamber, and the fuel injection nozzle has a multi-nozzle nozzle. The nozzle of the fuel injection nozzle is set to open opposite the inner circumferential wall surface of the combustion chamber, and the fuel spray is injected so as to collide toward the inner circumferential wall surface of the combustion chamber to uniformly disperse the fuel spray. The direction of fuel injection from multiple injection holes and the flow direction of intake air flowing into the combustion chamber are made to intersect at right angles, and furthermore, since combustion is poor during partial load, the ignitability of the fuel 144 is improved. Therefore, the glow plug is turned on to assist the ignition combustion, thereby allowing the alcohol fuel to ignite and burn well, preventing the discharge of unburned fuel or intermediate products, and allowing the main combustion to occur in the combustion chamber. An object of the present invention is to provide an alcohol engine that suppresses the generation of NOx.

[Means to solve the problem]

In order to achieve the above object, the present invention is as follows. That is, the present invention provides a structural wall forming a combustion chamber with an insulating structure disposed in a hole of a piston head, a flat glow plug attached to the cylinder head in a state extending toward the combustion chamber, and a glow plug on the combustion chamber side. The present invention relates to an alcohol engine comprising a fuel injection nozzle that is attached to the cylinder head in an extended state and that is provided with multiple injection holes that open opposite to the inner circumferential wall surface of the structural wall.

In this alcohol engine, the clove lug is located close to the inlet wall surface in the combustion chamber at the top dead center of the piston, and a portion of the injected fuel collides with a flat surface, and the fuel injection nozzle is located at the top dead center of the piston. The glow plug is located at a position deviated from the center of the combustion chamber toward the glow plug.

Further, in this alcohol engine, the structure includes a thin ceramic inner wall member that constitutes a wall surface of the subchamber;
and a heat insulating member disposed on the outer surface of the inner wall member.

Further, in this alcohol engine, a sensor detects the operating state of the engine, and the glow plug is turned on and heated in response to a partial load signal of a predetermined value or less from the sensor, and responds to a load signal of a predetermined value or more. and a controller that performs control to turn off the glow plug.

[Effect]

The alcohol engine according to the present invention is constructed as described above and operates as follows. In other words, this alcohol engine has a hole in the piston head! A combustion chamber is formed by a structure having a thermal structure, and a flat glow plug and a fuel injection nozzle are attached to the nozzle of the cylinder in such a manner that they extend into the combustion chamber at the top dead center of the piston, and the fuel injection nozzle is attached to the structure. has multiple injection holes opening facing the inner circumferential wall surface of the fuel injection nozzle, which increases the temperature within the combustion chamber in a short period of time, assists ignition combustion by using the glow plug as an ignition source, and allows air to flow from the fuel injection nozzle. The direction of the spray intersects the direction of intake air flowing into the combustion chamber at right angles, so that the alcohol fuel spray and the intake air can be ideally mixed and diffused, resulting in good vaporization mixing. can be achieved to achieve good combustion.

In particular, since the flat surface of the glow plug serves as a heat source for the injected fuel and is located close to the inlet wall surface in the combustion chamber, the squish flowing into the combustion chamber due to the rise of the piston is blocked by the back surface of the flat surface. The oblique plane side where the injected fuel collides becomes a space where air movement stops, that is, a part of the shadow. When the injected fuel collides with the oblique plane of a portion of the shad, the fuel impingement surface is cooled and droplets adhere, and the fuel is ignited by the glow plug in the absence of air flow. A stable flame core is formed.

Next, the squish that collided with the back surface of the flat surface goes around the flat surface and flows into the combustion chamber, allowing the next flame to propagate, thereby ensuring good ignition and combustion.

In addition, in this alcohol engine, the structural wall of the combustion chamber is composed of a thin ceramic inner wall member and a heat insulating member disposed on the outer surface of the inner wall member, so that the inner wall member has a wall facing the combustion chamber. It has a small heat capacity and can quickly follow the temperature of combustion gas or alcohol fuel, allowing the temperature to be adjusted to the optimum temperature.

Furthermore, this alcohol engine includes a sensor that detects the operating state of the engine, and a controller that turns on the glow plug in response to a partial load signal of less than a predetermined value from the sensor, so that when the engine is at partial load, The glow plug allows the fuel to be ignited and burned reliably and quickly, thereby suppressing the generation of unburned gas.

〔Example〕

Embodiments of the alcohol engine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing one embodiment of an alcohol engine according to the present invention, FIG. 2 is a cross-sectional view at &9n■ in FIG. 1, and FIG. 3 is an enlarged plan view of a glow plug.

This alcohol engine includes a structural wall 20 forming a combustion chamber 1 having an adiabatic structure, a combustion chamber 1 formed by the structural wall 20, a combustion chamber 1 formed by the structural wall 20, and a combustion chamber 1 formed by the structural wall 20. It has a fuel injection nozzle 4 attached to the cylinder head 10 at a position substantially in the center of the chamber 1 and biased toward the glow plug 3 side, and a glow plug 3 attached to the cylinder head 10. The combustion chamber 1 is arranged in a hole 9 formed in the piston head and is connected to a structural wall 2.
0, it has an adiabatic structure. Cylinder head 10 is fixed to cylinder block 8 via a gasket (not shown). A cylinder liner 13 is fitted into a cylinder formed in the cylinder block 8. Therefore, the upper surface of the piston, the cylinder liner 13, and the lower surface of the cylinder, which are the surfaces forming the combustion chamber 1, are as follows:
It is preferable to use a ceramic material that has high heat resistance, corrosion resistance, and alcohol resistance.

This alcohol engine is shown as an example operated as a two-stroke engine, and although intake and exhaust ports are not shown in the figure, an exhaust port with an exhaust valve is formed in the cylinder head 10 to form a uniflow type. You can also. Further, the intake port is formed in the lower part of the cylinder block 8 into which the cylinder liner 13 is fitted. It goes without saying that a four-cycle engine can be constructed by forming intake and exhaust ports in the cylinder head.

For this alcohol engine, especially the piston 1
The combustion chamber 1 formed in the piston head of 1 is connected to the structural wall 2.
0, the fuel injection nozzle 4 has a heat-insulating structure.
The glow plug 3 is attached to the throat 10 of the cylinder in such a way that it extends into the combustion chamber 1 at a part that is biased from the center of the combustion chamber 1 toward the flat glow plug 3 side, and that the glow plug 3 is attached to the inlet wall surface of the combustion chamber 1. 16 and extending into the combustion chamber 1 so that the injected fuel from the fuel injection nozzle 4 collides with the flat surface 25, and furthermore, the fuel injection nozzle 4 is arranged around the nozzle body 19. It is characterized by having a multi-stage multi-nozzle hole 17 nozzle port.

As shown in FIG. 2, this glow plug 3 is designed to provide a combustion engine so that the alcohol fuel sprayed from the fuel injection nozzle 4 toward the inner wall surface of the inlet portion 16 of the combustion chamber 1 can come into contact with it most efficiently. A heating surface, that is, a flat surface or oblique surface 25 of a ceramic member 6 in which a conductor 2 such as tungsten is embedded in the ceramic member is placed so as to face the injection port 17 of the fuel injection nozzle 4 in the circumferential direction near the inner wall surface of the entrance of the chamber 1. It is located.

This oblique surface 25 acts to prevent the squish flowing into the combustion chamber 1 due to the rise of the piston 11 (see the arrow in FIG. 1), and the air flow is stopped at the surface on the side where the injected fuel F collides with the oblique surface 25. A shadow portion S (see FIG. 2) is formed. The glow plug 3 is made of, for example, silicon nitride (Si:
+N4), ceramic material such as silicon carbide (SiC) 6
A conductor 2 such as tungsten is embedded in the
The conductor 2 is heated by passing a current through it.

With this arrangement, the alcohol fuel sprayed from the fuel injection nozzle 4 collides with the heating surface, that is, the flat surface 25, but some of it becomes droplets and flows down along the flat surface of the ceramic member 6. , the fuel liquid accumulates in the region indicated by the symbol B, and the fuel liquid ignites the alcohol fuel well. The globe lug 3 is turned on and off by a controller 15 depending on the operating state of the engine. In particular, regarding this alcohol engine, the operating state of the engine is detected by the load sensor 12 or the rotation sensor 14, and the detection signal is manually input to the controller 15, and the detection signal is a detection value below a predetermined set value, for example, the engine In response to the partial load signal, the glow plug 3 is turned on and heated by a command from the controller 15 to promote vaporization of the alcohol fuel and assist in ignition and combustion of the fuel. The engine load signal is the fuel injection pump 18
It can be detected by detecting the flow rate of fuel f4 supplied to the fuel injection nozzle 4, or by the load sensor 12 which detects the amount of depression of the accelerator pedal.

Further, as shown in FIGS. 4 and 5, the fuel injection nozzle 4 has a nozzle body 19 in which a needle valve 24 is disposed, which penetrates through a heat insulating member of the cylinder head 10.
The nozzle body] 9 is installed in such a manner that it extends toward the combustion chamber l side. This nozzle body 19 is arranged so as to extend into the combustion chamber 1 at the top dead center of the piston, and is formed around the tip end portion 23 of the nozzle body 19 and facing the inner circumferential surface of the inner wall member 7 of the combustion chamber 1. It has multiple injection holes 17 that are open.

Further, among these nozzle holes 17, it is preferable for the nozzle hole 17 facing the glow plug 3 to have a larger diameter than the other nozzle holes 17 for ignition and combustion of the fuel. When the position of the multiple injection holes 17 of the fuel injection nozzle 4 is set as described above, a space is formed in the wake in the combustion chamber 1, and the alcohol fuel spray and intake air are ideally mixed and diffused. I can do it.

Furthermore, the fuel injection timing of this fuel injection nozzle 4 is as follows:
It is set before the top dead center of the compression stroke. In addition, when the alcohol fuel injected from the fuel injection nozzle 4 collides with the inner wall surface of the inner wall member 7 of the combustion chamber 1 in a state where combustion is active and the wall temperature of the combustion chamber 1 is high, the wall temperature increases. is 3
At temperatures above 00'C, the alcohol fuel will burst and scatter.
The fuel spray mixes better with the intake air. In addition, when the wall temperature is low, such as when the engine is under partial load, the collision energy of the alcohol fuel is sufficient to generate a good mixture with the intake air, and the glow plug 3 is turned on and heated. The injected fuel F injected toward No. 3 is reliably and quickly ignited and combusted.

In this alcohol engine, the structural wall 20 that constitutes the heat insulating structure of the combustion chamber 1 is arranged on the inner surface of the heat insulating member 5 made of a low heat conductive material such as aluminum titanate, potassium titanate, sodium titanate, etc. The inner wall member 7 is made of a heat-resistant and alcohol-resistant ceramic material such as silicon nitride (SisN4), silicon carbide (SiC), or a composite material. Furthermore, by manufacturing the heat insulating member 5 from the above-mentioned material having a small Young's modulus, it can function as a buffer material that absorbs the impact of an explosion on the inner wall member 7. Moreover, the inner wall member 7
The shell structure in which the entire surface is covered with the heat insulating member 5 is constructed by integrally casting the inner wall member 7 with the heat insulating member 5 located on the outside. In addition, by configuring the inner wall member 7 between the combustion chamber 1 and the inlet portion 16 to have a thin wall structure and an outer surface insulating structure, the inner wall member 7 is able to withstand the temperature of the mixture of intake air and alcohol fuel flowing in, and the combustion temperature. This improves followability, and at low temperatures such as at the start of combustion or at partial load, the combustion chamber 1
The combustion gas immediately raises the temperature to a temperature suitable for vaporization combustion. Further, at high temperatures such as when the engine is under full load, the combustion chamber 1 is immediately cooled by the alcohol fuel sprayed from the fuel injection nozzle 4, and the temperature is similarly adjusted to a temperature suitable for vaporization combustion. Therefore, the inner walls of the combustion chamber 1 and the inlet section 16 can always be maintained at the optimum temperature for vaporizing the alcohol fuel.

Further, this alcohol engine can operate in two cycles by taking in intake air from an intake boat formed at the lower part of the cylinder block 8, and can also operate in a diesel cycle. In this case, if the amount of intake air is restricted, the fuel equivalence ratio within the combustion chamber 1 can be increased, and the main combustion can be performed in the combustion chamber 1, thereby suppressing the generation of No. 1. Furthermore, after combustion in the combustion chamber 1, the flame spreads from the combustion chamber 1 into the cylinder liner 13. Therefore, even if alcohol fuel adheres to the inner wall member 7 of the inlet portion 16, the attached fuel burns and reacts when the flame blows out, so unburned fuel or intermediate products are removed from the exhaust stroke. Since the flame is blown out from the combustion chamber 1, the fuel equivalence ratio and combustion temperature are lowered, so that the generation of N08 can be further suppressed.

Next, an example of the fuel injection nozzle 4 used in this alcohol engine will be explained with reference to FIGS. 4 and 5. FIG. 4 is a sectional view showing an example of the fuel injection nozzle 4 used in this alcohol engine, and FIG. 5 is a sectional view taken along line A-A in FIG. 4. This fuel injection nozzle 4
has a needle valve 24 that is movable up and down within a nozzle body 19 disposed in the cylinder head 10. Since the nozzle body 19 and needle valve 24 are arranged inside the combustion chamber 1, they are made of silicon nitride (Si, 1N), which is heat resistant and alcohol resistant.
a) Manufactured from ceramic materials such as silicon carbide (SiC) and composite materials. Further, a heat insulating material made of ceramic fiber such as zirconia fiber is arranged on the outer surface of the nozzle body 19, and a shielding material made of a ceramic material such as silicon nitride (Si3N4) or silicon carbide (SiC) is placed on the outer surface of the heat insulating material. Thermal elements can also be placed by chemical vapor deposition (CvD), interlocking, etc. to further improve heat resistance. If the fuel injection nozzle 4 is made of the above-mentioned material, there will be no problems such as sliding problems, water contamination problems, and high temperature problems. A fuel il path 21 is formed between the inner wall surface of the nozzle body 19 and the outer surface of the needle valve 24. Further, at the tip of the nozzle body 19, a nozzle sack 22, which serves as a fuel reservoir, is provided.
A nozzle hole 17 is formed for injecting the fuel accumulated in the nozzle sack 22 to the outside. Therefore, the needle valve 24
When the nozzle body 19 moves upwardly against the spring force under the injection pressure of the fuel injection pump 18, the fuel passage 2
1 and the nozzle sack 22 communicate with each other, whereby alcohol fuel is uniformly dispersed and sprayed over the entire circumference of the nozzle body 19 from the nozzle holes 17 formed in multiple stages. It turns out.

Next, with reference to FIGS. 1, 2, 3, and 6,
The operation of the alcohol engine according to the present invention will be explained. FIG. 6 is a process flow diagram showing an example of the operation of the alcohol engine according to the present invention.

When the engine starts, the fuel injection pump 8, glow plug 3, etc. are driven and controlled. First, as a first step, by driving the engine, the engine rotation speed is detected by the rotation sensor 14, and the detection signal is input to the controller 15. The engine load is detected by the load sensor 12, and the detection signal is input to the controller 15 (step 30).

In the controller 15, the engine rotation speed X detected by the rotation sensor 17 is set to a predetermined rotation speed X1. A comparison is made to determine whether or not the value is larger than that (step 31).

If the engine rotation speed NE is the predetermined rotation speed x 1. If it is smaller, the engine is running at low speed and the structural wall 20. which forms the combustion chamber I is smaller. Since the inner wall member 7 is not at a high temperature, even if the alcohol fuel is injected into the combustion chamber 1 from the fuel injection nozzle 4, the injected fuel cannot take vaporization heat from the wall surface. Therefore, the glow plug 3 is turned on by a command from the controller 15, and current is supplied to the conductor 2 of the glow plug 3. The glow plug 3 supplied with current is heated by the electric power and reaches a high temperature (step 34).
).

Engine rotation speed N is the predetermined rotation speed N! , it is determined that the engine is operating at high speed and under high load, and that the inner wall member 7 of the structural wall 20 constituting the combustion chamber 1 is at a high temperature. A comparison is made to determine whether or not the detected engine load is greater than a predetermined engine load LEI calculated in advance (step 32).

When the engine load L4 is smaller than the predetermined engine load LE+, the engine is under low load and the inner wall member 7 of the structural wall 20 forming the combustion chamber 1 is not at a high temperature, so the fuel injection nozzle 4 Even if alcohol fuel is injected into the combustion chamber 1, the injection-resistant fuel cannot absorb the heat of vaporization from the wall surface.

Therefore, a current is supplied to the conductor 2 of the glow plug 3 according to a command from the controller 15 (step 34).

The glow plug 3 supplied with electric current is heated by the electric power and reaches a high temperature, and the alcohol fuel injected from the fuel injection nozzle 4 collides with the glow plug 3 heated by the electric power, and is heated by the glow plug 3. Ignition and combustion occur smoothly, and the generation of unburned aldehyde gases can be prevented.

Furthermore, when the engine load is larger than the predetermined engine load LSI, the engine is operating at high speed and under high load, and combustion is actively occurring, and the temperature inside the combustion chamber becomes high and the combustion chamber 1 The inner wall member 7 of the structural wall body 20 that constitutes the structure is at a high temperature.

Therefore, even if the glow plug 3 is not turned on and heated, the alcohol fuel is well promoted to vaporize and is in a state where it can be ignited and burned well. The supplied current is stopped, that is, the glow plug 3 is turned off (step 33). Therefore, the alcohol fuel injected from the fuel injection nozzle 4 collides with the inner wall member 7 heated by the combustion gas, removes heat from the inner wall member 7, and actively vaporizes the alcohol fuel, producing a good air-fuel mixture. The injected alcohol fuel ignites and burns smoothly, and the generation of unburned gas such as intermediate products of aldehydes can be prevented.

〔Effect of the invention〕

The alcohol engine according to the present invention is configured as described above and has the following effects.

That is, this alcohol engine includes a structural wall forming a combustion chamber with an insulating structure disposed in a hole in a piston head, a flat glow plug attached to a cylinder head extending toward the combustion chamber, and a structure wall body forming a combustion chamber with an insulating structure, and a flat glow plug attached to the cylinder head in a state extending toward the combustion chamber. Extending to the side 6
a) Since the fuel injection nozzle is attached to the nozzle of the cylinder and has multiple injection holes opening facing the inner circumferential wall surface of the structural wall, the temperature inside the combustion chamber can be increased in a short period of time, and the By using the glow plug as an ignition source, ignition combustion is assisted, and the direction of the spray from the fuel injection nozzle is perpendicular to the inflow direction of the intake air flowing into the combustion chamber. The injected fuel configured to have multiple injection holes is uniformly distributed on the wall surface of the combustion chamber and injected so as to collide with the inner wall surface, and a space is formed in the wake in the combustion chamber, and alcohol fuel is sprayed. It is possible to ideally mix and diffuse the intake air and the intake air, thereby achieving good vaporization mixing and good combustion.

In particular, since the flat surface of the glow plug serves as a heat source for the injected fuel and is located close to the inlet wall surface in the combustion chamber, the squish flowing into the combustion chamber due to the rise of the piston is blocked by the back surface of the flat surface. The oblique plane side where the injected fuel collides becomes a space where air movement stops, that is, a part of the shadow. When the injected fuel collides with the oblique plane of a portion of the shad, the fuel impingement surface is cooled and droplets adhere, and the fuel is ignited by the glow plug in the absence of air flow. A stable flame core is formed.

Next, the skin that has collided with the back surface of the flat surface goes around the flat surface and flows into the combustion chamber, allowing the next flame to propagate, thereby ensuring good ignition and combustion. Therefore, since good combustion can be achieved, the discharge of unburned fuel or intermediate products can be prevented, and the generation of NOx can be suppressed.

Further, although the flame blows out from the combustion chamber into the cylinder liner, even if the alcohol fuel injected from the fuel injection nozzle toward the wall surface of the artificial part adheres to the wall surface, the attached Since the fuel burns and reacts when the flame is blown out, unburnt fuel or intermediate products are not exhausted during the exhaust stroke, and as the flame is blown out of the combustion chamber, the fuel equivalence ratio rapidly decreases. Since the combustion temperature is lowered, the generation of NO8 can be further suppressed.

In addition, in this alcohol engine, the structural wall of the combustion chamber is composed of a thin ceramic inner wall member and a heat insulating member disposed on the outer surface of the inner wall member, so that the heat capacity of the inner wall portion, that is, the wall surface facing the combustion chamber. becomes small, and can quickly follow the combustion gas temperature or alcohol fuel temperature and adjust the temperature to the optimum temperature. Therefore, when the temperature is high, such as under full load, the alcohol fuel sprayed from the fuel injection nozzle can cool the wall surface of the combustion chamber to an optimum temperature 2, and the temperature of the combustion chamber does not become too high. Therefore, the nozzle body of the fuel injection nozzle located in the combustion chamber is prevented from becoming overripe, vaporization within the nozzle body of the fuel injection nozzle is suppressed, and good spraying can be achieved. The alcohol fuel present in the injection nozzle will not vaporize and the spray state will become abnormal, the spray from the fuel injection nozzle will be performed normally, and the subsequent ignition and combustion of the fuel will proceed smoothly f') It will be done. Further, at low temperatures such as during partial load, only the inner wall member of the combustion chamber is immediately raised by combustion gas,
To quickly vaporize and burn injected alcohol fuel.

Furthermore, in this alcohol engine, the glow plug is turned on and heated in response to a sensor that detects the operating state of the engine, and a load signal from the sensor that is less than or equal to a predetermined value.

Since the controller includes a controller that controls turning off the glow plug in response to a line signal, when the detected value of the operating state of the engine is a signal value higher than a predetermined set value, in other words, when the engine is at high speed and under high load, the inside of the combustion chamber is Since the temperature is high, do not apply current to the glow plug to heat it (
However, since alcohol fuel vaporizes well and can be reliably ignited and burned, the glow plug is turned off, and the alcohol fuel sprayed on the inner wall cools and removes heat, causing abnormal ignition in the operating area. To prevent this, alcohol fuel is actively vaporized, a good alcohol mixture is generated, and ignition and combustion are performed smoothly.

In addition, when the detected value of the engine operating state is a signal value lower than the predetermined set value, in other words, when the engine is running at low speed and low load, the combustion chamber is not at a high temperature, so the controller responds to the operating state. A current is passed through the glow plug according to a command to heat the glow plug, and the injected alcohol fuel collides with the heated glow plug to remove heat from the glow plug to promote vaporization of the alcohol fuel and achieve good mixing. By generating gas, the injected alcohol fuel can be smoothly ignited and burned, thereby preventing the generation of unburned gas such as aldehyde, and also preventing the generation of exhaust gas odor.

Therefore, in the alcohol engine according to the present invention, the melting chamber can be maintained at an optimum temperature by on/off control of the glow plug in the combustion chamber in the entire operating range, so that the alcohol fuel injected from the fuel injection nozzle is Even though the latent heat of vaporization is high, the ignition combustion is constantly assisted by colliding with the glow plug, producing a good air-fuel mixture, ensuring ignition, achieving smooth combustion, and eliminating unburned gas. can be prevented from occurring.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the alcohol engine according to the present invention, Fig. 2 is a sectional view taken along line ■-■ in Fig. 1, and Fig. 3 is a glow lamp used in the alcohol engine of Fig. 1. 4 is a sectional view showing an example of a fuel injection nozzle used in the alcohol engine of FIG. 1, FIG. 5 is a sectional view taken along line A-A in FIG. 4, and FIG. The figure is a processing flow diagram showing an example of the operation of the alcohol engine according to the present invention. 1-- Combustion chamber, 2-- Conductor, 3-- Glow plug, 4-- Fuel injection nozzle, 5---a
Heat member, 6-- Ceramic member, 7-- Inner wall member, 9-- Hole, 11=-- Piston, 12--
-One load sensor 14--One rotation sensor, 1
5-1 Controller, 16-.-Population Department, 17-.
-- Nozzle hole, 19 --- Nozzle body, 20 --- 1.- Structural wall body, 25 --- 111 oblique surface, F-- Injected fuel, S-- Part of shadow .

Claims (4)

[Claims] (1) A structural wall forming a combustion chamber with an insulating structure placed in the hole of the piston head, a flat glow plug attached to the cylinder head extending toward the combustion chamber, and a flat glow plug extending toward the combustion chamber. An alcohol engine comprising: a fuel injection nozzle that is attached to the cylinder head and has multiple injection holes that open opposite to the inner circumferential wall surface of the structural wall. (2) The glow plug is located close to the inlet wall surface in the combustion chamber at the top dead center of the piston, and is arranged so that a portion of the injected fuel collides with the flat surface, and the fuel injection nozzle is located at the top dead center of the piston. 2. The alcohol engine according to claim 1, wherein the alcohol engine is located at a position biased toward the glow plug from the center of the combustion chamber. (3) The alcohol engine according to claim 1, wherein the structural wall body is composed of a thin ceramic inner wall member constituting the wall surface of the combustion chamber, and a heat insulating member disposed on the entire outside of the inner wall member. (4) A sensor that detects the operating state of the engine, and in response to a load signal of a predetermined value or less from the sensor, turns on and heats the glow plug, and in response to a load signal of a predetermined value or more, turns on the glow plug. The alcohol engine according to claim 1, further comprising a controller that controls turning off the alcohol engine.