JPH10196424A - Compression ignition type combustion method for air-fuel mixture, and compression ignition type piston internal combustion engine for air-fuel mixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent excessive early ignition and misfire by controlling timing of self-ignition of air-fuel mixture. SOLUTION: A compression ignition type piston internal combustion engine for air-fuel mixture is composed of a mixing means 1 for fuel and air, a piston 3 to be reciprocated in a cylinder 2 and for compressing air-fuel mixture to the high temperature just before self-ignition, and a control piston 4 as an auxiliary compressing means for additionally compressing air-fuel mixture compressed by decreasing the total clearance capacity for forming a combustion chamber near the top dead center, for transitionally increasing the temperature of air-fuel mixture, and for self-igniting air-fuel mixture all together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustible air-fuel mixture in a cylinder which is compressed by a piston so as not to cause self-ignition before a top dead center. The present invention relates to a compression ignition combustion method for an air-fuel mixture that generates a simultaneous self-ignition of the combustible air-fuel mixture by giving a further additional temperature rise, and a compression-ignition piston internal combustion engine for the air-fuel mixture.

[0002]

2. Description of the Related Art Among the current piston internal combustion engines, a diesel engine (particularly, a direct injection type diesel engine which directly injects fuel into a combustion chamber) has the highest thermal efficiency. However, since the exhaust gas of the diesel engine has characteristics of excess oxygen due to lean combustion and less unburned hydrocarbons,
Without the development of an exhaust treatment method with a high purification rate as found in a three-way catalyst of a spark ignition gasoline engine,
It has reached today. NOx is one of the substances emitted from the diesel engine and considered difficult to treat.

[0003] In recent years, a compression ignition type piston internal combustion engine has been studied as an engine capable of reducing NOx emission by about 1/10 to 1/20 without impairing the thermal efficiency of a conventional diesel engine. For example, "Research on Gasoline Premixed Compression Ignition Engine" published in the Japan Society of Automotive Engineers, Academic Lecture Preprint No. 951 (May 1995), and the 73rd Annual Meeting of the Japan Society of Mechanical Engineers ( III), No.95
-10 (September 1995), "Emission Characteristics of Diesel Combustion with Lean Premixed Gas Mixture by Early Fuel Injection," both compress air-fuel mixture in cylinders and ignite all at once in a high-temperature atmosphere. Therefore, as shown in FIGS. 13 and 14, it is reported that NOx can be reduced to 1/10 to 1/20 of the conventional value.

A practical example of this type of engine is 1950
There is the Lohman 500, which was marketed as an auxiliary engine for bicycles in the 1980s. This engine is a variable compression ratio engine and can change the compression ratio to about 15 to 80. The control of the compression ratio is adjusted by the driver according to the operating conditions.

[0005]

In the diesel engine and the compression ignition type piston internal combustion engine, the output is controlled in principle by increasing or decreasing the amount of fuel supplied. This is one of the reasons. However, in the compression ignition type piston internal combustion engine, since the difference in the amount of fuel to be supplied, that is, the difference in the air-fuel ratio of the air-fuel mixture affects the ignition timing, the range of the air-fuel ratio in which the optimum ignition timing is obtained is narrow. Otherwise, premature ignition or misfire may occur.

[0006] Prevention of premature ignition and misfire in the compression ignition type piston internal combustion engine is nothing but the control of ignition timing. Conventionally, this means uses a variable compression ratio mechanism, controls intake air temperature,
There are ideas for controlling the amount of R (exhaust gas recirculation) and controlling the fuel composition. These are all effective means for changing the ignition timing, but at the same time, all these means have the same disadvantages in controlling the ignition timing. The disadvantage is that
The control of the factor for changing the ignition timing is to be completed before the start of compression or by the time when the air-fuel mixture is prepared. Therefore, after execution of the control means, during the period in which the air-fuel mixture is compressed by the piston and led to a high-temperature and high-pressure state, these control means wait, as it were, for ignition. Here, the period from the time when the air-fuel mixture starts to receive the compression action by the piston to the time when the mixture is ignited is defined as an ignition preparation period.

When an arbitrary ignition timing is to be obtained by using the above-mentioned ignition control means without using a system which requires a comparison between a control amount and a control result, such as a feedback control system or a learning control, the ignition preparation period must be reduced. You must know the length in advance. That is, it is necessary to know when the air-fuel mixture before being compressed by the piston ignites as a result of being compressed by the subsequent piston. However, it is not possible to use a simple formula to express the time required for the mixture to be continuously compressed by the piston and ignited at a certain temperature and pressure.

[0008] There are three factors that govern the length of the ignition preparation period of a combustible mixture: the composition of the mixture, the time history of temperature, and the time history of pressure. In the case of an engine, the composition of the mixture is
Fuel type, air-fuel ratio, residual gas ratio, EGR amount (exhaust gas reintake by exhaust gas recirculation system),
It is mainly determined by humidity. The time history of the temperature and the pressure is mainly determined by the composition of the air-fuel mixture, the temperature and the pressure at the compression start time, the dimensions of the engine (stroke and compression ratio, etc.), the number of revolutions, the cooling water temperature, the lubricating oil temperature, and the like. . That is, all of the above factors affect the length of the ignition preparation period of the compression ignition type piston internal combustion engine, and the length of the ignition preparation period cannot be considered as a function of any one factor.

Due to the complexity of the factors that determine the ignition preparation period, it is not easy to generate ignition at any time in a compression ignition type piston internal combustion engine. Is left.

In the compression ignition type piston internal combustion engine, it is also an important subject that misfiring easily occurs. In the experiments of the present inventors, it was confirmed that, at 750 rotations, a misfire could be caused only by lowering the intake air temperature by 25 ° C.

[0011] The Lohman 500 is sensitive to changes in the ignition timing with respect to the compression ratio, and is commercially available but has not been widely used. This indicates that control is not easy.

The compression ignition type piston internal combustion engine is characterized by a narrow range of operating conditions for obtaining an appropriate ignition timing. For example, as described above, the ignition timing is very sensitive to the compression ratio and the intake air temperature. This demands that the feedback control system and the ignition timing control device based on learning control perform a wide range of control with good responsiveness at the time of transient fluctuation of the rotation speed and load and at the time of starting.

According to the experiments of the present inventors, for example, 100
It is clear that in order to change the equivalence ratio from 0 to 3000 rotations to 0.2 to 1.0 and to obtain ignition at top dead center under all conditions, the intake air temperature must be changed by 150 ° C or more. became. Obviously, it is not easy to control such a wide temperature condition according to a change in load or rotation speed.

From the above, in order to put the high thermal efficiency and low NOx emission characteristics of the compression ignition type piston internal combustion engine to practical use, it is necessary to prevent premature ignition and misfire, and to make it optional like conventional diesel engines and spark ignition type engines. It is indispensable to perform combustion at this time, and for that purpose, a more reliable means compared to the control means (use of a variable compression ratio mechanism, control of intake air temperature, control of EGR amount, control of fuel composition) Need.

Based on the above technical background, the present inventors have concluded that the following technical development is necessary to put the compression ignition combustion of the air-fuel mixture into practical use. (1) The ignition means for igniting the air-fuel mixture must be capable of inducing self-ignition near TDC as a result of the execution of the ignition means, and may easily cause misfire. Must not have any properties.

(2) The ignition means capable of reliably inducing self-ignition in the vicinity of the top dead center must be one in which the ignition timing can be easily controlled by any control means.

(3) A control device for controlling the ignition timing using the ignition means must be constructed.

The present inventors have studied the ignition means and the control device satisfying the above three conditions by examining various factors affecting the ignition timing in the compression ignition combustion method of the air-fuel mixture by using an elementary reaction model. The validity of the obtained knowledge was confirmed by an actual machine.

The elementary reaction model used in the study phase of the present invention is a carbon number developed by researchers CK Westbrook and WJ Pitz of Lawrence Livermore National Laboratory in the United States. Based on the elementary reaction model of saturated hydrocarbons of 8 or less, the present inventors have verified and improved the ignition delay time by the rapid compression device.

The present inventors use the elementary reaction model to
The compression ignition combustion method of the air-fuel mixture was studied from all angles, and as a result, the compression by the piston was limited to a compression ratio that did not ignite the air-fuel mixture by itself, and the temperature of 10 to 300 K was observed at any time near the top dead center. It was concluded that it was necessary to add the rise as an ignition aid for the mixture to lead to simultaneous self-ignition.

That is, the present inventors compress the air-fuel mixture in the cylinder by a piston so as not to cause self-ignition before the top dead center, and give an additional temperature rise to the air-fuel mixture near the top dead center. Therefore, focusing on the technical idea of the present invention that induces simultaneous self-ignition of the air-fuel mixture, and as a result of further research and development, premature ignition and misfire by controlling the ignition timing of the air-fuel mixture in compression ignition combustion. The present invention attains the object of preventing the problem. In the present invention, whether or not self-ignition occurs is determined strictly based on a state in which 90% or more of the heat generated due to self-ignition has been completed.
In other words, the expression that self-ignition does not occur before top dead center means that the heat generation up to top dead center is less than 90%, and does not indicate the start time of temperature rise due to self-ignition. Please note.

[0022]

According to a first aspect of the present invention, there is provided a compression ignition combustion method for a fuel-air mixture which is compressed by a piston so as not to cause self-ignition before a top dead center. The combustible air-fuel mixture in the cylinder has a further additional temperature increase near the top dead center to generate simultaneous self-ignition of the combustible air-fuel mixture.

The present invention (the second invention described in claim 2)
In a compression ignition type piston internal combustion engine, a combustible mixture in a cylinder is compressed by a piston reciprocating in a cylinder so as not to cause self-ignition before a top dead center. The combustible mixture in the cylinder is self-ignited by providing an additional temperature increase to the gas.

Further, another invention of the present invention (third invention)
Compression-ignition type piston internal combustion engine is an engine that compresses a combustible air-fuel mixture in a cylinder so as not to cause self-ignition before a top dead center by a piston whose displacement is expressed by a set of crank-connecting rods. The combustible air-fuel mixture is additionally compressed at an arbitrary time by an auxiliary compression means for giving an additional volume change different from the volume change due to the displacement of the piston, and the combustible air-fuel mixture is self-ignited by the temperature rise. Things.

Further, according to another aspect of the present invention (a fourth aspect of the present invention), there is provided an ignition timing control apparatus for a compression ignition combustion, wherein the compression ignition type combustion method for an air-fuel mixture of the first aspect and the second and third aspects of the present invention. In the compression ignition type piston internal combustion engine, a sensor that detects the ignition timing of the air-fuel mixture, the output from the sensor and the air-fuel ratio, the fuel supply amount, the throttle valve opening, the EGR valve opening, the intake air amount, the intake air temperature, The additional temperature rise can be determined by using all or part of the output from the sensor that detects the cooling water temperature, the lubricating oil temperature, the temperature of the mixture during compression, the rotation speed, and the operating state of the means for providing the additional temperature rise. It controls the timing and amount of feeding.

There are the following methods for realizing the technical ideas of the first, second and third inventions. (1) A small control piston having a stroke volume of 5 to 70% of the top dead center clearance volume is provided at the upper part of the combustion chamber, and additional compression is performed by the control piston at an appropriate time.
Raises the temperature of the air-fuel mixture to cause simultaneous self-ignition.

(2) A mechanism capable of moving the displacement of the piston separately from the displacement caused by the pair of cranks and the connecting rod to additionally compress a volume corresponding to 5 to 70% of the top dead center gap volume at an appropriate time. By doing so, the temperature of the air-fuel mixture is raised to cause simultaneous self-ignition.

(3) The combustion chamber is divided into two or more parts (for example, sub-chambers are installed), and can be opened and closed between the main combustion chamber in contact with the piston top surface at the top dead center and combustion chambers other than the main combustion chamber. A partition (for example, an umbrella valve) is installed. By closing the partition near the top dead center, the gap volume at the top dead center is reduced, and by increasing the compression pressure, the temperature of the air-fuel mixture is raised to cause simultaneous self-ignition.

(4) A part of the air-fuel mixture is spark-ignited, or ignition oil is injected into the air-fuel mixture, and the combustion increases the pressure of the entire air-fuel mixture to raise the temperature of the air-fuel mixture, thereby contributing to the combustion. A simultaneous self-ignition of the air-fuel mixture that was not performed is generated.

According to the above method (1), it is possible to ignite at an arbitrary timing by adjusting the operation timing of the control piston. Some of the work performed on the piston as it expands may be recovered.

In the method (2), the displacement of the piston is driven at an appropriate time separately from the displacement regulated by the pair of cranks and the connecting rod to reduce the volume of the combustion chamber.
The compression pressure is increased to measure the temperature rise and cause simultaneous ignition. By adjusting this timing, the ignition timing can be arbitrarily controlled.

In the method (3), the amount of air-fuel mixture in the combustion chamber in contact with the piston at the top dead center is changed by adjusting the timing of opening and closing the partition provided between the plurality of combustion chambers. Thus, the compression pressure is adjusted to control the ignition timing. Since the power required for the control is an amount necessary for opening and closing the partition, the control can be performed with a small driving force. However, there is a factor that the heat loss increases due to the complicated shape of the combustion chamber and the efficiency is reduced. Further, depending on the timing when the air-fuel mixture in the combustion chamber other than the main combustion chamber is burned, the same effect as when the combustion period is prolonged occurs, and there is a factor that causes a decrease in efficiency due to a decrease in isocapacity.

The above method (4) is applicable to the first invention and the second invention.
This is a method for realizing the technical idea of the present invention, in which a part of the air-fuel mixture is burned by spray combustion seen in a diesel engine or flame propagation combustion seen in a spark ignition type engine, and the remaining mixture is increased by a pressure increase due to the combustion. It measures the temperature rise of the air and ignites it all at once. However, for an air-fuel mixture that is difficult to ignite, it is necessary to apply a relatively large amount of fuel to the spray combustion or the flame propagation combustion, which is a factor that reduces the NOx reduction effect.

According to the fourth aspect of the present invention, in the first, second, and third aspects of the present invention, a sensor for detecting an ignition timing of the air-fuel mixture, an output from the sensor, Operation to give air-fuel ratio, fuel supply amount, throttle valve opening, EGR valve opening, intake air amount, intake air temperature, cooling water temperature, lubricating oil temperature, mixture temperature during compression, rotation speed, additional temperature rise A control device for controlling the timing and amount of additional temperature rise using all or a part of the output from the sensor for detecting the state is configured to arbitrarily control the ignition timing.

(Action) In the compression ignition combustion method of the air-fuel mixture according to the first invention having the above-described structure, the combustible air-fuel mixture in the cylinder compressed by the piston is prevented from causing self-ignition before the top dead center. The additional self-ignition of the combustible air-fuel mixture is performed by giving an additional additional temperature rise to the combustible air-fuel mixture near the top dead center.

In the compression-ignition-type piston internal combustion engine of the second aspect of the invention having the above-described structure, the combustible air-fuel mixture in the cylinder is prevented from self-ignition before the top dead center by the piston reciprocating in the cylinder. In the engine which compresses the combustible mixture, the combustible mixture is given an additional additional temperature rise at any time, thereby simultaneously igniting the combustible mixture in the cylinder.

In the compression-ignition-type piston internal combustion engine according to the third aspect of the invention having the above-described structure, the combustible air-fuel mixture in the cylinder is converted before the top dead center by a piston whose displacement is expressed by a set of crank-connecting rods. In an engine that compresses so as not to cause self-ignition, the combustible air-fuel mixture is additionally compressed at any time by an auxiliary compression means that provides an additional volume change different from the volume change due to the displacement of the piston, The combustible air-fuel mixture is simultaneously self-ignited by the temperature rise caused by the above.

The ignition timing control apparatus in the compression ignition type combustion method of the air-fuel mixture according to the fourth aspect of the present invention having the above-described structure is characterized in that
The ignition method according to the invention, the second invention, and the third invention is based on a sensor for detecting the ignition timing of the air-fuel mixture, an output from the sensor, an air-fuel ratio, a fuel supply amount, a throttle valve opening, an EGR valve opening, and intake air. Using all or part of the output from the sensor to detect the operating state of the volume, intake air temperature, cooling water temperature, lubricating oil temperature, mixture temperature during compression, rotational speed, means for providing an additional temperature rise, The timing and amount of the additional temperature rise are controlled, and the ignition timing is arbitrarily controlled.

[0039]

According to the first aspect of the present invention, there is provided a method for compression-ignition combustion of an air-fuel mixture according to the first aspect of the present invention. By giving a further additional temperature rise to the combustible mixture near the top dead center to generate simultaneous self-ignition of the combustible mixture, and adjusting the timing of the additional temperature rise, The ignition timing of the combustible air-fuel mixture is adjusted to provide an effect of preventing premature ignition and misfire.

In the compression-ignition-type piston internal combustion engine of the air-fuel mixture according to the second aspect of the present invention, the combustible air-fuel mixture in the cylinder is prevented from self-ignition before the top dead center by the piston reciprocating in the cylinder. In the engine which compresses the combustible mixture, the combustible mixture is subjected to a further additional temperature rise at any time to generate the simultaneous self-ignition of the combustible mixture, and the time for giving the additional temperature rise is determined. By adjusting, the timing at which the combustible mixture in the cylinder self-ignites is adjusted, and an effect of preventing premature ignition and misfire is achieved.

The compression-ignition-type piston internal combustion engine of the air-fuel mixture according to the third aspect of the present invention having the above-mentioned operation is characterized in that the combustible air-fuel mixture in the cylinder is converted before the top dead center by a piston whose displacement is expressed by a set of crank-connecting rods. In an engine that compresses so as not to cause self-ignition, the combustible air-fuel mixture is additionally compressed at any time by an auxiliary compression means that provides an additional volume change different from the volume change due to the displacement of the piston, By causing the combustible mixture to self-ignite at the same time due to the temperature rise caused by the above, and by adjusting the timing of giving the additional compression, there is an effect of preventing premature ignition and misfire.

According to the fourth aspect of the present invention, there is provided an ignition timing control apparatus for a compression ignition combustion method of an air-fuel mixture according to the first aspect.
The ignition method according to the invention, the second invention, and the third invention is based on a sensor for detecting the ignition timing of the air-fuel mixture, an output from the sensor, an air-fuel ratio, a fuel supply amount, a throttle valve opening, an EGR valve opening, and intake air. Using all or part of the output from the sensor to detect the operating state of the volume, intake air temperature, cooling water temperature, lubricating oil temperature, mixture temperature during compression, rotational speed, means for providing an additional temperature rise, Controls the timing and amount of additional temperature rise and allows the ignition timing to be controlled arbitrarily, prevents premature ignition and misfire under all operating conditions, thermal efficiency and unburned hydrocarbons in exhaust gas This has the effect of controlling the ignition timing to be optimal for reducing harmful substances such as nitrogen oxides and carbon monoxide.

[0043]

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

(First Embodiment) The compression ignition combustion method of the air-fuel mixture and the compression ignition piston internal combustion engine of the air-fuel mixture according to the first embodiment mix fuel and air as shown in FIGS. A mixing means 1, a piston 3 for reciprocating in a cylinder 2 to which the air-fuel mixture is supplied from the mixing means 1 and compressing the air-fuel mixture to a high temperature just before self-ignition, and a volume of the combustion chamber near top dead center Control piston as auxiliary compression means for simultaneously compressing the air-fuel mixture by self-igniting the air-fuel mixture by additionally compressing the compressed air-fuel mixture and transiently increasing the temperature of the air-fuel mixture. 4.

As shown in FIGS. 1 and 2, the mixing means 1 is provided with an air supply port in which the intake air supplied into the air supply passage 13 is sucked into the cylinder 2 and the intake valve 11 is disposed. The fuel injection valve 10 injects fuel into the vicinity of the suction hole 12, and is configured to mix the sucked air and fuel and supply the mixture into the cylinder 2 as an air-fuel mixture.

As shown in FIGS. 1 and 2, the cylinder 2 is cooled by cooling water circulating in the water jacket, and the piston 3 connected to the crank 32 via the connecting rod 31 is inserted. , And reciprocate.

As shown in FIGS. 1 to 3, the control piston 4 is constituted by a cylindrical body inserted in a hydraulic cylinder 40 formed in a vertical direction on a cylinder head, and is connected to the hydraulic piston 41 by a rod. They are integrally connected.

As shown in FIG. 3, the hydraulic supply device 5 includes a hydraulic pump 51 which communicates with an oil tank 50 and supplies a hydraulic pressure, an accumulator 52 for storing the hydraulic pressure from the hydraulic pump 51, and an accumulator 52. And two solenoid valves 53 for controlling the supply of the stored hydraulic pressure to the hydraulic cylinder 40. The hydraulic pressure is supplied to the upper part of the hydraulic piston 41 by controlling the application of the solenoid valve 53 by a controller (not shown). As shown in FIG. 4, the control piston 4 is controlled to move downward a predetermined time before the top dead center in the compression stroke, and to move the control piston 4 upward from the exhaust stroke to the air supply stroke. Things.

As shown in FIG. 1, the control piston 4 has a top dead center clearance volume V determined by a compression ratio.
Relative to _1, the ratio of adjusted volume V _c by the control piston 4 operated by the hydraulic pressure is represented by the following equation, it is set between the _{V c / (V 1 + V} c) × 100 5~70% .

The ratio of the top dead center total clearance volume V ₁ to the adjustment volume V _c by the control piston 4 is V _c /
(V ₁ + V _c ) is determined by the range of the fuel-air ratio to be used and the range of the engine speed.

FIG. 5 shows the temperature variation according to the crank angle of the mixture in the cylinder 2. The reference (base) compression ratio means that the piston 3 has a top dead center total clearance volume V
₁ and refers to the compression ratio represented by the sum (V ₁ + V _c) of the previous volume V _c of the control piston 4 is lifted, it is expressed by the following equation. Reference compression ratio ε ₀ = (V ₁ + V _c + V _h ) / (V ₁ +
V _c )

[0052] In the above equation V _h, the piston stroke volume V _c is the control piston working volume V ₁ was a piston top dead center void volume.

The total compression ratio ε _T is equal to the control piston 4
Operates and V _c = 0, and is expressed by the following equation. ε _T = (V ₁ + V _c + V _h ) / V ₁

Therefore, there is a relationship of ε _T > ε ₀ .

As an example, if the stroke volume (cylinder volume) of the engine is 400 cc and ε ₀ is 16, V _c + V ₁ = 26.6 cc

Assuming that the adjustment volume (operating volume) V _c of the control piston 4 is 13.3 cc, V _c / (V
A _{1 + V c) = 0.5 ε} T = 32.0.

The first embodiment (FIG. 2) is an example of an engine using gasoline as fuel. As described above, the stroke volume of the engine is 0.4 liter (per cylinder), the reference compression ratio ε ₀ is 14, and the adjusted volume ratio V _c / (V ₁ + V _c ) of the control piston 4 is 0. .5. The overall compression ratio Ε _T is 28.

In the compression ignition combustion method of the air-fuel mixture and the piston engine of the compression air-fuel mixture of the air-fuel mixture according to the first embodiment having the above-described configuration, an air throttle valve is arranged by the fuel injection valve 10 during the intake stroke of the fuel. The fuel is injected toward the suction hole 12 communicating with the supply passage 13 that is not provided.

The operation period of the control piston 4 is 360 ° (4 cycles are 720 ° per cycle).
The maximum advance angle is 60 ° before the compression top dead center at the start of operation, and the latest operation start is 10 ° after the compression top dead center.

The control piston 4 operates by hydraulic pressure, and supplies high-pressure oil stored in the accumulator 52 to the hydraulic cylinder 40 by on / off control of the solenoid valve 53 to operate the hydraulic piston 41. And the volume inside the combustion chamber 30 is additionally reduced, and the combustion chamber 3
The pressure in the combustion chamber 30 is raised to a temperature at which self-ignition is possible by increasing the pressure in the combustion chamber 30. The oil supply timing is controlled by changing the on / off application timing of the solenoid valve 53. .

The compression ignition combustion method of the air-fuel mixture and the compression-ignition piston internal combustion engine of the air-fuel mixture according to the first embodiment having the above-described operation are the compression ignition of the air-fuel mixture, and the control piston 4 is operated. Since the volume in the combustion chamber 30 is additionally reduced, the pressure in the combustion chamber 30 is increased, and the temperature of the air-fuel mixture in the combustion chamber 30 is raised to a temperature at which self-ignition is possible. Since the ignition timing can be adjusted in exactly the same manner as the injection timing of the diesel engine or the diesel engine, it is possible to prevent premature ignition or misfire.

In the first embodiment, the operation timing and the operation period of the control piston 4 are controlled by the on / off control of the hydraulic pressure by the solenoid valve 53 controlled by the controller. Since it is controlled, it can be arbitrarily controlled as needed, and has the effect of being flexible.

(Second Embodiment) As shown in FIGS. 6 to 8, a method of compression-ignition-type combustion of an air-fuel mixture and a compression-ignition-type piston internal combustion engine of an air-fuel mixture according to a second embodiment are shown in FIGS. It can be said to be a Qi diesel engine. The main difference from the first embodiment is that fuel is injected from the fuel injection valve 10 into the combustion chamber 30.

The stroke volume of the engine is 0.33 liter (per cylinder). ε ₀ is 12, V _c / (V ₁ +
V _c ) is 0.5 and ε _T is 24.

The operation period and the advance range of the control piston 4 are the same as those in the first embodiment, but the hydraulic system in the cylinder head is different as shown in FIGS.

The oil supplied from the hydraulic line for lubricating the engine enters the power piston P, and pushes up the power piston P by rotation of the camshaft C (driven by the engine at half the number of revolutions of the crankshaft). The camshaft is driven at a speed reduced by half from the engine via a timer capable of changing the phase.

The resulting high oil pressure is guided to the hydraulic piston 41 to operate the control piston 4. Adjustment of the operation start time of the control piston 4
This is performed by a timer of the power piston driving cam shaft C.

In the compression-ignition-type piston internal combustion engine of the air-fuel mixture according to the second embodiment having the above-described structure and operation, the control piston 4 is operated to additionally reduce the volume in the combustion chamber, and Since the pressure is increased and the temperature of the air-fuel mixture in the combustion chamber 30 is raised to a temperature at which self-ignition can be performed as shown in FIG. 6, the ignition timing can be adjusted, so that premature ignition or misfire can be prevented. .

(Third Embodiment) Next, an example of an ignition timing control device according to a third embodiment (fourth invention) will be described. Third
The embodiment shows an ignition timing control device for a compression ignition type piston internal combustion engine of an air-fuel mixture based on the third invention.

In the third embodiment, as shown in FIGS. 9 to 11, an ignition timing detecting means for detecting an ignition timing, an operating state detecting means for detecting an operating state, and an operating state of the control piston 4 are detected. A control piston operating state detecting means, an arithmetic unit for outputting an optimal operation start timing and an operating amount of the control piston 4 using output values obtained from these detecting means, and an operation of the control piston 4 based on an output of the arithmetic unit And control means for controlling to a suitable condition.

The ignition timing detecting means in the third embodiment assumes the use of a pressure sensor for detecting the pressure of the mixture in the cylinder. In addition to this, the temperature of the mixture by combustion using the temperature sensor is used. It is also possible to substitute for detection of rise, detection of light emission due to combustion using an optical sensor, detection of flame using an ion probe, detection of vibration due to combustion using an acceleration sensor, and the like.

As shown in FIG. 9, the operating state detecting means in the third embodiment includes a fuel supply amount detecting means for detecting a fuel supply amount, a throttle opening detecting means for detecting a throttle valve opening, an EGR valve. An EGR opening degree detecting means for detecting an opening degree, an intake air amount detecting means for detecting an intake air amount, an intake air temperature detecting means for detecting an intake air temperature, and a cooling water temperature detecting means for detecting a cooling water temperature. And a lubricating oil temperature detecting means for detecting the lubricating oil temperature, and a rotational speed detecting means for detecting the rotational speed.

The control piston operation state detecting means in the third embodiment is constituted by control piston displacement amount detecting means for detecting the operation amount of the control piston with respect to the crank angle.

The control piston is driven by a hydraulic circuit, and the drive amount, drive timing, and drive speed are controlled by a solenoid valve. The solenoid valve is driven according to a control signal from a controller. The controller includes an ignition timing detector, a control piston displacement detector, a rotational speed detector, a fuel supply detector, an intake air detector, a throttle valve opening detector, an EGR valve opening detector,
Signals from the intake air temperature detecting device, the cooling water temperature detecting device, and the lubricating oil temperature detecting device are input.

Hereinafter, some embodiments of the control will be described.

As shown in FIG. 10, when the drive start timing of the control piston is set to D1, and the pressure in the cylinder obtained from the ignition timing detecting device detects self-ignition before the top dead center, the control is started. By setting the driving start timing of the piston to D2, it is possible to control the timing of self-ignition in the next cycle after the top dead center.

As shown in FIG. 11, in an operation in which the displacement of the control piston is changed from the position X0 before the driving to the position X1 after the driving, the pressure in the cylinder obtained from the ignition timing detecting device is controlled. If self-ignition is detected much earlier than the end of driving of the piston, it is possible to avoid unnecessary driving of the control piston after occurrence of self-ignition by changing the position after driving to X2.

In the ignition timing control device of the third embodiment (fourth invention) having the above-described configuration, when the engine is started, it is determined that the engine is started cold based on signals from the cooling water temperature detecting device and the lubricating oil temperature detecting device. In this case, it is possible to achieve a reliable start by maximizing the drive amount of the control piston and making the drive timing earlier. On the other hand, when the temperature of each part of the engine is high, such as when the engine is restarted, the drive energy of the control piston is reduced to reduce the drive energy.

Even if the cooling water temperature detecting device and the lubricating oil temperature detecting device detect a high temperature when the engine is restarted, under conditions where the outside air temperature is low, such as in winter, the signal from the intake air temperature detecting device is used. A misfire is prevented by increasing the control piston drive amount.

Estimating the composition of the combustible mixture in the cylinder is effective for controlling the control piston appropriately. The amount of air introduced into the cylinder is estimated based on signals from the rotational speed detector, the fuel supply amount detector, the intake air amount detector, the intake air temperature detector, and the cooling water detector. The air-fuel ratio is estimated based on a signal from the supply amount detecting device. In addition to the estimated air amount and the estimated air-fuel ratio, signals from the throttle valve opening detection device and the EGR valve opening detection device are added to estimate the composition of the air-fuel mixture. The degree of difficulty of occurrence of self-ignition is determined from the estimated mixture composition, and optimal control of the control piston is performed. For example, even if the mixture is close to the stoichiometric mixture, if a large amount of EGR is included, self-ignition is unlikely to occur, so the control piston drive amount is increased.

Further, the ignition timing control device of the third embodiment (fourth invention) is effective in preventing a misfire or an early ignition even under a transient operation condition. Under the transient condition of shifting from the steady operation to the deceleration, when the air-fuel ratio changes to the lean side despite the high rotation speed, it is possible to prevent the misfire by increasing the control piston drive amount. On the other hand, under the transient condition of shifting from the steady operation to the acceleration, the air-fuel ratio changes toward the stoichiometric air-fuel mixture in a state where the rotational speed is low. Therefore, it is possible to prevent early ignition by delaying the control piston drive timing.

As described above, by using the ignition timing control device of the third embodiment (fourth invention), reliable start-up, steady-state operation, and transient operation can be achieved under all operating conditions. It is possible to obtain ignition and an appropriate ignition timing.

The above embodiments have been described by way of example only, and the present invention is not limited to these embodiments. The present invention is not limited to the claims, the detailed description of the invention, and the drawings. Modifications and additions are possible without departing from the technical idea of the present invention that can be recognized by those skilled in the art.

That is, as an example in the first embodiment, the movement of the control piston is controlled by hydraulic pressure.
Adjustment of the movement start point (point A in FIG. 5) is performed by ON-OF of the solenoid valve.
Although the example in which the F timing is performed by the electric signal has been described,
The present invention is not limited to them, and FIG.
As shown in FIG. 2, a control piston 4 urged by a spring 56 is driven by a cam 55 provided on the cylinder head, and a timer (not shown) is provided on the cam phase or cam shaft. Thus, a mode of adjusting the movement start point can be adopted.

In the third embodiment, an example in which the upper piston is moved upward by using the cam mechanism based on the change in the angle of the control piston has been described. However, the present invention is not limited thereto. The hydraulic circuit may be installed in the connecting rod pump, and the piston displacement may be changed near the top dead center by hydraulic pressure.

That is, as the variable mechanism of the piston displacement using the hydraulic pressure, there is a similar mechanism for moving the upper part of the piston up and down by the hydraulic pressure as seen in a variable compression ratio system or the like. While the conventional compression ratio variable system is used to change the compression ratio for each cycle, in the present system, during the short period from the latter half of the compression stroke to the beginning of the expansion stroke, the base compression is changed. Used to change rapidly from ratio to high compression ratio. When the displacement of the piston is changed by the hydraulic system, it is easy to arbitrarily control the timing and amount of moving the piston up and down.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining the principle of a mixture compression ignition combustion method and a mixture compression ignition piston internal combustion engine according to a first embodiment of the present invention;

FIG. 2 is a sectional view showing a control piston according to the first embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram illustrating a control piston and a hydraulic pressure supply device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a stroke of a control piston according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a temperature course of an air-fuel mixture in a combustion chamber according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a compression speed and a temperature change of an air-fuel mixture in the present invention.

FIG. 7 is an explanatory diagram showing a mixture compression ignition type piston engine according to a second embodiment of the present invention.

FIG. 8 is a hydraulic circuit diagram showing a control piston and a hydraulic pressure supply device according to a second embodiment of the present invention.

FIG. 9 is a schematic diagram showing an ignition timing control device of a mixture compression ignition type piston engine according to a third embodiment of the present invention.

FIG. 10 is a diagram showing control correspondence of a control piston drive timing by an ignition timing control device according to a third embodiment of the present invention.

FIG. 11 is a diagram showing a control correspondence of a control piston drive amount by an ignition timing control device of a mixture compression ignition type piston engine according to a third embodiment of the present invention.

FIG. 12 is a sectional view showing another embodiment of the control piston drive mechanism of the present invention.

FIG. 13 is a graph showing exhaust gas characteristics of a conventional homogeneous charge compression ignition engine.

FIG. 14 is a diagram showing transition of inlet air temperature and pressure of a conventional homogeneous charge compression ignition engine.

[Explanation of symbols]

 1 mixing means 2 cylinder 3 piston 4 control piston

Continuing on the front page (72) Inventor Tetsu Yamazaki 41-Cho Chu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Institute, Inc. Address No. 1 Inside Toyota Central Research Laboratory, Inc.

Claims (2)

[Claims] 1. A further additional temperature rise for the combustible mixture in the cylinder, which is compressed by a piston so as not to cause self-ignition before top dead center, near the top dead center for the combustible mixture. A compression ignition combustion method for the air-fuel mixture, wherein the combustion of the combustible air-fuel mixture is performed simultaneously. 2. An internal combustion engine in which a combustible mixture in a cylinder is compressed by a piston reciprocating in a cylinder so that self-ignition does not occur before a top dead center. Wherein the combustible mixture in the cylinder is self-ignited by providing a further additional temperature increase.