JP5995754B2 - Premixed compression ignition type engine and its operation control method - Google Patents

Description

  The present invention relates to a premixed compression ignition type engine in which a hydrocarbon-based main fuel is mixed with fresh air sucked into a combustion chamber to form an air-fuel mixture, and the air-fuel mixture is compressed in the combustion chamber to self-ignite and burn. And an operation control method thereof.

As an engine that can achieve low pollution and high efficiency, a so-called premixed compression is performed in which a premixed mixture of air and fuel is introduced into a combustion chamber and the premixed mixture is self-ignited by adiabatic compression of the piston and burned. A premixed compression ignition type engine that performs ignition (HCCI) combustion is known (see, for example, Patent Documents 1 and 2).
Such a premixed compression ignition type engine can improve the efficiency by increasing the compression ratio, and can reduce the NOx by burning the fuel in a lean state. Has the merit that the premixed gas can be easily ignited and combusted even when gaseous fuel such as natural gas city gas is used.

In a premixed compression ignition engine, it is important that the premixed gas is self-ignited at an appropriate time in the vicinity of the top dead center in the combustion chamber in order to maintain stable operation and further improve the efficiency. For example, if the intake air temperature is too high, the self-ignition timing will be excessively advanced and knocking will occur. Conversely, if the intake air temperature is too low, the self-ignition timing will be excessively retarded and thermal efficiency will be reduced or misfires will occur. There is a problem that occurs.
Therefore, the premixed compression ignition type engine described in Patent Documents 1 and 2 has a lower ignition point than the main fuel, separately from the main fuel such as natural gas mainly composed of methane supplied to the combustion chamber. By adding auxiliary fuel such as light oil and butane with the addition amount control, the self-ignition timing is maintained within the target self-ignition timing range.

JP 2012-057470 A JP 2000-274285 A

In the control of the self-ignition timing of the conventional premixed compression ignition type engine, all use auxiliary fuel whose ignition point is lower than that of the main fuel, but particularly in a high rotation region where the engine speed is very high. Even if the amount of auxiliary fuel added with a low ignition point is increased, the air-fuel mixture in the combustion chamber may not be sufficiently ignited and misfire may occur. Such misfires make the combustion state unstable and lead to deterioration of engine cycle fluctuations.
The present invention has been made paying attention to such a point, and its purpose is to maintain the self-ignition timing at an appropriate time even in a severe operating state such as a high rotation region in a premixed compression ignition type engine. However, the present invention is to provide a technique capable of suppressing deterioration of cycle fluctuation.

In order to achieve this object, a premixed compression ignition engine according to the present invention comprises:
A premixed compression ignition engine in which a hydrocarbon-based main fuel is mixed with fresh air sucked into a combustion chamber to form an air-fuel mixture, and the air-fuel mixture is compressed in the combustion chamber to self-ignite and burn.
The first characteristic configuration is
Self-ignition timing detection means for detecting the self-ignition timing of the air-fuel mixture in the combustion chamber, and self-ignition timing adjustment means capable of adjusting the self-ignition timing of the air-fuel mixture in the combustion chamber,
Cycle content detecting means for detecting deterioration of cycle fluctuation, and ethane content rate adjusting means capable of adjusting the ethane content rate in the combustion chamber,
Performing self-ignition timing control for controlling the self-ignition timing adjustment means so that the self-ignition timing detected by the self-ignition timing detection means is maintained within a target self-ignition timing range; There is a control means for executing cycle fluctuation suppression control for controlling the ethane content rate adjusting means so that deterioration of the detected cycle fluctuation is suppressed.

The inventors of the present invention have intensively studied that, among hydrocarbons, ethane has a lower carbon number and higher ignition point than other hydrocarbons such as propane and butane, but ignition until ignition is reached. In the latter part of the process, it was discovered that the generation rate of OH radicals tends to increase and the rate of temperature rise tends to be accelerated. Furthermore, the mechanism of deterioration of cycle fluctuations in a premixed compression ignition engine is the content of this ethane. Has been found to be greatly related, and the present invention has been completed.
That is, according to the first characteristic configuration, by executing the self-ignition timing control, the ethane content rate of the mixture in the combustion chamber is changed in the cycle fluctuation suppression control that is performed simultaneously, and the mixture Even when the ignitability changes, the self-ignition timing of the air-fuel mixture in the combustion chamber is maintained within an appropriate target self-ignition timing range. At the same time, by executing the cycle fluctuation suppression control, the ethane content of the air-fuel mixture in the combustion chamber is controlled to an appropriate value, and deterioration of the cycle fluctuation is suppressed.

In short, by executing these self-ignition timing control and cycle fluctuation suppression control simultaneously, the ethane content of the mixture in the combustion chamber increases as much as possible within the allowable range, and the temperature rise rate in the late stage of the ignition process is maintained high. As a result, the deterioration of cycle fluctuation due to misfire is suppressed, and at the same time, the excessive change in the self-ignition timing accompanying the increase in the ethane content is moderately suppressed, and the self-ignition timing at that time is within the appropriate target self-ignition timing range. Will be maintained.
Therefore, according to the present invention, it is possible to realize a premixed compression ignition engine capable of suppressing deterioration of cycle fluctuations while maintaining the self-ignition timing at an appropriate time even in a severe operating state such as a high rotation region. it can.

In addition to the first characteristic configuration described above, the second characteristic configuration of the premixed compression ignition type engine according to the present invention includes:
It is configured as a multi-cylinder type with multiple combustion chambers.
The self-ignition timing adjusting means is capable of adjusting the self-ignition timing of each of the plurality of combustion chambers at once, and the individual self-adjustment capable of individually adjusting the self-ignition timing of each of the plurality of combustion chambers. It is in the point which consists of ignition timing adjustment means.

According to the second characteristic configuration described above, when the premixed compression self-ignition engine according to the present invention is configured as a multi-cylinder type, the overall self-ignition timing adjusting means and the individual self-ignition timing adjusting means are provided. Thus, the self-ignition timing of each of the plurality of combustion chambers can be adjusted with high accuracy and quickly within the target self-ignition timing range.
That is, when the self-ignition timing of each of the plurality of combustion chambers deviates from the target self-ignition timing range by adjusting the ethane content rate by cycle fluctuation suppression control, first, all the self-ignition timing adjustment means The self-ignition time can be adjusted to a value close to the target self-ignition time range, and then each self-ignition time can be individually adjusted within the target self-ignition time range by the individual self-ignition time adjusting means.

The third characteristic configuration of the premixed compression ignition type engine according to the present invention is in addition to any of the first to second characteristic configurations,
The ethane content rate adjusting means is an ethane addition means capable of adding ethane with adjusting the addition amount to the combustion chamber.

  According to the third characteristic configuration, the ethane content rate in the combustion chamber can be adjusted by adding the ethane to the combustion chamber and adjusting the addition amount by the ethane addition means. .

The fourth characteristic configuration of the premixed compression ignition type engine according to the present invention is in addition to any of the first to third characteristic configurations,
The main fuel is natural gas mainly composed of methane.

  According to the fourth characteristic configuration, ethane has a low ignition point with respect to methane and has a significantly high temperature rise rate in the late stage of the ignition process. Therefore, the main fuel supplied to the combustion chamber is mainly composed of methane. In the case of natural gas, the combustion stability of the air-fuel mixture can be adjusted quickly and significantly only by adjusting the ethane content of the air-fuel mixture in the combustion chamber in the above-described cycle fluctuation suppression control. Can be more reliably suppressed.

In order to achieve this object, an operation control method for a premixed compression ignition engine according to the present invention includes:
Operation control method of a premixed compression ignition engine in which hydrocarbon-based main fuel is mixed with fresh air sucked into the combustion chamber to form an air-fuel mixture, and the air-fuel mixture is compressed in the combustion chamber to self-ignite and burn Because
Its feature configuration is
Self-ignition timing detection means for detecting the self-ignition timing of the air-fuel mixture in the combustion chamber, and self-ignition timing adjustment means capable of adjusting the self-ignition timing of the air-fuel mixture in the combustion chamber,
Cycle content detecting means for detecting the deterioration of the cycle fluctuation, and ethane content rate adjusting means capable of adjusting the ethane content rate in the combustion chamber are provided.
Performing self-ignition timing control for controlling the self-ignition timing adjustment means so that the self-ignition timing detected by the self-ignition timing detection means is maintained within a target self-ignition timing range; The present invention resides in executing cycle fluctuation suppression control for controlling the ethane content rate adjusting means so as to suppress the deterioration of the detected cycle fluctuation.

  According to the operation control method for the premixed compression ignition type engine, as with the premixed compression ignition type engine according to the present invention described above, the self-ignition timing adjusting means and the ethane content rate adjusting means are provided. Since the ignition timing control and the cycle fluctuation suppression control are executed, the same effects as those described in the premixed compression ignition type engine according to the present invention can be achieved.

Schematic configuration diagram of premixed compression ignition engine Graph showing the ignition delay period for hydrocarbon fuels

An embodiment of a premixed compression ignition type engine and an operation control method thereof according to the present invention will be described based on the drawings.
A premixed compression ignition type engine (hereinafter simply referred to as “engine”) 1 shown in FIG. 1 is configured as a multi-cylinder type in which a plurality of combustion chambers 10 are arranged. Although not shown in detail, each combustion chamber 10 is connected to a crankshaft 6 via a connecting rod in a cylinder, a lower surface of a cylinder head connected to the upper part of the cylinder, and a cylinder, and is freely reciprocally movable. And the top surface of the piston housed in the housing.
An intake passage 21 and an exhaust passage 31 are opened in the combustion chamber 10, an intake valve 20 is provided on the intake passage 21 side of the combustion chamber 10, and an exhaust valve 30 is provided on the exhaust passage 31 side of the combustion chamber 10. ing.

  In the intake passage 21 of the engine 1, main fuel, which is a natural gas-based city gas mainly composed of methane, supplied from the outside to the air flowing through the intake passage 21 is adjusted by the supply amount of the fuel supply valve 24. Are mixed to form an air-fuel mixture M. In addition, a throttle valve 22 is provided on the downstream side of the mixer 23 in the intake passage 21. Further, on the downstream side of the throttle valve 22 in the intake passage 21, there is a heat exchanger 25 that heats the air-fuel mixture M sucked into the combustion chamber 10 by heat exchange with engine coolant having a relatively high temperature (for example, 80 ° C.). Is provided. Then, the air-fuel mixture M that has passed through the heat exchanger 25 is distributed to the respective combustion chambers 10.

When the intake valve 20 is opened, the piston descends from the top dead center, whereby an intake stroke for taking in the air-fuel mixture M from the intake passage 21 to the combustion chamber 10 is performed, and then the intake valve 20 is closed. When the piston rises in the state of being made, a compression stroke for compressing the air-fuel mixture M in the combustion chamber 10 is performed.
In the latter part of this compression stroke, the mixture M is heated by adiabatic compression, the main fuel oxidation reaction proceeds, and when the temperature rises to the ignition temperature of the main fuel where the chain branching reaction occurs, self-ignition occurs and mixing occurs. So-called HCCI combustion, in which the gas M burns, is performed.
In the expansion stroke following the compression stroke, the piston rises while the exhaust valve 30 is opened, whereby an exhaust stroke in which the exhaust gas E in the combustion chamber 10 is discharged to the exhaust passage 31 is performed.
In this way, the engine 1 is configured to repeatedly perform a series of operations for performing each stroke in the order of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke.

Further, a cooling water supply amount adjusting valve 26 capable of adjusting the supply amount of engine cooling water to the heat exchanger 25 provided in the intake passage 21 is provided. The cooling water supply amount adjusting valve 26 adjusts the amount of cooling water supplied to the heat exchanger 25 to adjust the heating capacity of the heat exchanger 25 with respect to the air-fuel mixture M, so that fresh air is supplied to the plurality of combustion chambers 10. It functions as a fresh air temperature adjusting means for adjusting the temperature of the air-fuel mixture M to be sucked.
Further, by adjusting the temperature of the air-fuel mixture M sucked into the combustion chamber 10 by the cooling water supply amount adjusting valve 26, the temperature of the air-fuel mixture M compressed in the plurality of combustion chambers 10 can be changed simultaneously. Therefore, the cooling water supply amount adjustment valve 26 functions as an overall self-ignition timing adjusting means Y1 that simultaneously adjusts the self-ignition timing of the air-fuel mixture M in each of the plurality of combustion chambers 10.

  The engine 1 includes an in-cylinder pressure sensor 8 that detects the pressure in the combustion chamber 10 (hereinafter referred to as “in-cylinder pressure”) and an angle of the crankshaft 6 as various sensors, as in a general HCCI engine. A crank angle sensor 7 for detecting (hereinafter referred to as “crank angle”) is provided.

Each combustion chamber 10 is provided with a spark plug 11 capable of generating a spark, and this spark plug 11 is compressed in the combustion chamber 1a when a voltage is applied by an ignition circuit 12 controlled by the ECU 50. Sparks can be generated in the air-fuel mixture M and the self-ignition of the air-fuel mixture M can be induced (assisted).
Further, since this spark generation timing affects the self-ignition timing of the air-fuel mixture M, the ignition circuit 12 individually adjusts the spark generation timing by the spark plugs 11 provided in each of the plurality of combustion chambers 10. Thus, the self-ignition timing adjusting means Y2 that individually adjusts the self-ignition timing of the air-fuel mixture M in each of the plurality of combustion chambers 10 functions.

  Various controls of the engine 1 are performed by an ECU (Engine Control Unit) 50, which detects a self-ignition timing of the mixture M in the combustion chamber 10 by executing a predetermined computer program. It functions as a timing detection means 51, a cycle fluctuation detection means 52 that detects deterioration of cycle fluctuation, a control means 53 that executes operation control of the engine 1, and the like.

  The self-ignition timing detection means 51 analyzes the change state of the in-cylinder pressure detected by the in-cylinder pressure sensor 8 while referring to the crank angle detected by the crank angle sensor 7, and the combustion mass ratio 50% ( The situation regarding the combustion timing such as the time when the combustion of 50% fuel is completed), the center of gravity timing of the heat generation rate or the maximum heat generation timing is obtained, and the self-ignition timing of the air-fuel mixture M is detected from this situation.

  The cycle fluctuation detecting means 52 analyzes the in-cylinder pressure detected by the in-cylinder pressure sensor 8 while referring to the crank angle detected by the crank angle sensor 7, calculates the indicated mean effective pressure, and shows the indicated mean A value obtained by dividing the standard deviation of the effective pressure by the average value of the same pressure is obtained as a coefficient of variation COV in a predetermined number of cycles, and a state in which the coefficient of variation COV increases beyond an allowable range is detected as deterioration of cycle fluctuation. .

  The control means 53 simultaneously executes self-ignition timing control and cycle fluctuation suppression control, which will be described later, and controls the opening of the fuel supply valve 24 based on the oxygen concentration of the exhaust gas E detected by the oxygen sensor 32. The air-fuel ratio of the air-fuel ratio M generated by the mixer 23 is maintained at a desired fuel-lean target air-fuel ratio suitable for HCCI combustion, and the rotation of the crankshaft 6 obtained from the detection result of the crank angle sensor 7 Various controls such as a rotational speed maintenance control for controlling the opening degree of the throttle valve 22 are performed so that the speed is maintained at a desired rotational speed.

The basic configuration of the engine 1 has been described above. Further, the engine 1 is for suppressing deterioration of cycle fluctuations while maintaining the self-ignition timing at an appropriate time even in a severe operating state such as a high rotation region. As a configuration, an ethane content rate adjusting means X capable of adjusting the ethane content rate of the air-fuel mixture M in the combustion chamber 10 is provided, and a control means 53 on which the ECU 50 functions includes an overall self ignition timing adjusting means Y1 and an individual self ignition timing. While performing self-ignition timing control which controls self-ignition timing adjustment means Y1 and Y2 which consist of adjustment means Y2, cycle fluctuation suppression control which controls ethane content rate adjustment means X is performed.
The detailed configuration will be described below.

In the engine 1 of the present embodiment, when the control means 53 that the ECU 50 functions performs self-ignition timing control, the self-ignition timing detected by the self-ignition timing detection means 51 falls within a predetermined target self-ignition timing range. The self-ignition timing adjusting means Y1, Y2 are controlled so as to be maintained.
Specifically, each self-ignition timing in the plurality of combustion chambers 10 detected by the self-ignition timing detection means 51 is a target self-ignition timing range near the top dead center (for example, a range of 6 ° ATDC to 10 ° ATDC). When the deviation is advanced, the degree of opening of the cooling water supply amount adjustment valve 26 that functions as the overall self-ignition timing adjusting means Y1 is reduced, and the air-fuel mixture M sucked into the plurality of combustion chambers 10 is reduced. Reduce the temperature. Then, due to the temperature drop of the air-fuel mixture M, the respective self-ignition timings in the plurality of combustion chambers 10 are simultaneously shifted to the retard side and returned to the target self-ignition timing range.
Conversely, when the self-ignition timings in the plurality of combustion chambers 10 detected by the self-ignition timing detection means 51 deviate from the target self-ignition timing range toward the retard side, the cooling water supply amount adjustment The temperature of the air-fuel mixture M sucked into the plurality of combustion chambers 10 is increased by increasing the opening of the valve 26. Then, as the temperature of the air-fuel mixture M rises, the respective self-ignition timings in the plurality of combustion chambers 10 shift to the advance side all at once and return to the target self-ignition timing range.
In addition, even when the self-ignition timings in the plurality of combustion chambers 10 are adjusted by the overall self-ignition timing adjusting means Y1, the self-ignition times in some of the combustion chambers 10 do not return within the target self-ignition timing range. Controls the spark generation timing of the spark plug 11 by controlling the ignition circuit 12 that functions as the individual self-ignition timing adjusting means Y2 only for the part of the combustion chambers 10, thereby setting the self-ignition timing to the target self. Return to the ignition timing range.

The ethane content rate adjusting means X is composed of an ethane addition section (an example of ethane addition means) 60 capable of adding ethane to the combustion chamber 10 with adjustment of the addition amount.
Specifically, ethane obtained in a natural gas distillation process or the like is stored in a pressurized state in a portable high-pressure gas container 63, and the ethane addition unit 60 is stored in the high-pressure gas container 63. Ethane is mixed with the main fuel supplied to the mixer 23 with the addition amount adjustment by the ethane addition amount adjustment valve 61.

Next, the combustion characteristics of ethane, which is a new finding that the present inventors have completed the present application, will be described below with reference to FIG.
2 shows natural gas and methane (CH ₄ ), ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ), isobutane (iso-C ₄ H ₁₀ ), and normal butane ( for n-C ₄ H ₁₀₎ fuel of each of the a graph showing the ignition delay period when allowed to self-ignite constant volume system a mixture of its fuel and air. In the initial conditions, the equivalence ratio of the air-fuel mixture is 0.5, the pressure of the air-fuel mixture is 6.08 MPa, and the temperature of the air-fuel mixture is 1200K. In FIG. 2, the first stage of the ignition process indicates a time width in the ignition process until the temperature of each fuel rises from 1200 K to 1210 K after ignition, and the second stage of the ignition process indicates that the temperature of each combustion starts from 1210 K. The time width in the ignition process up to is shown.
Like propane and butane (iso or normal), ethane has a lower ignition point than methane, which is the main component of natural gas. That is, in the air-fuel mixture M combusted in the combustion chamber 10, the self-ignition timing shifts to the retard side as the ethane content rate decreases.
However, compared with propane, isobutane, and normal butane, which have low ignition points, ethane has a larger time width in the early ignition process in the ignition delay period as shown in FIG. Smallest. This is due to the fact that ethane tends to increase the rate of OH radical generation late in the ignition process and accelerate the temperature rise rate compared to other hydrocarbons. That is, in the air-fuel mixture M combusted in the combustion chamber 10, the higher the ethane content rate, the more the chain branching reaction in the combustion chamber 10 is prevented from freezing in the later stage of the ignition process. become.

And in the engine 1 of this embodiment, the control means 53 which ECU50 functions performs the cycle fluctuation suppression control demonstrated below simultaneously with the said self-ignition timing control.
Specifically, in the cycle fluctuation suppression control, when deterioration of cycle fluctuation is detected by the cycle fluctuation detecting means 52 described above, the main amount supplied to the mixer 23 by increasing the opening of the ethane addition amount adjusting valve 61 is increased. The ethane content rate adjusting means X is controlled in such a manner that the ethane content rate in the combustion chamber 10 is increased by increasing the amount of ethane added to the fuel.
That is, it is avoided that the ethane content of the air-fuel mixture M in the combustion chamber 10 decreases below the lower limit of an appropriate adjustment range in which deterioration of cycle fluctuation can be suppressed.

Further, in the cycle fluctuation suppression control, in order to emphasize the suppression of cycle fluctuation, the air-fuel mixture M in the combustion chamber 10 is limited to the extent that the actual self-ignition timing is maintained within the target self-ignition timing range by the self-ignition timing control. Increase the ethane content of as much as possible. Specifically, in the self-ignition timing control, in the cycle fluctuation suppression control, the opening degree of the ethane addition amount adjustment valve 61 until the temperature adjustment of the air-fuel mixture M by the opening degree adjustment of the cooling water supply amount adjustment valve 26 reaches a limit. Is gradually expanded to suppress cycle fluctuations.
In addition, the natural gas type | system | group city gas used as a main fuel has methane as a main component, and since the methane has a higher ignition point than ethane, the higher the ethane addition rate of the mixture M in the combustion chamber 10, The ignitability of the air-fuel mixture M becomes high, and the self-ignition timing is shifted to the advance side.
Therefore, in the cycle fluctuation suppression control, when the ethane addition amount adjustment valve 61 is gradually enlarged to increase the ethane addition amount, the self-ignition timing control advances the advance side of the self-ignition timing. In order to prevent this change, the opening degree of the cooling water supply amount adjusting valve 26 is gradually reduced, and the temperature of the air-fuel mixture M is adjusted to the lower side, for example, at a normal temperature limit.

[Other Embodiments]
Finally, other embodiments of the present invention will be described. Note that the configuration of each embodiment described below is not limited to being applied independently, and can be applied in combination with the configuration of other embodiments as long as no contradiction arises.
(1) In the above embodiment, the ethane content rate adjusting means X is configured as the ethane addition unit 60 that can add ethane to the combustion chamber 10 with the addition amount adjustment. Alternatively, the ethane content in the combustion chamber may be adjusted by separating ethane from the fuel supplied to the combustion chamber 10 with the separation amount adjustment.

(2) In the above embodiment, the ethane addition unit 60 is configured to add ethane stored in the high-pressure gas container 63. However, a part of the main fuel, that is, natural gas is taken out, and the known gas is extracted from the natural gas. Separation of ethane by an oxidative coupling method (for example, see JP-A-05-070372) or a purification method such as a membrane separation method or a pressure condensation method (for example, see JP-A-2009-167411) You may comprise so that it may supply to the part 60. FIG.
Further, it may be configured such that raw materials other than the main fuel are supplied from the outside, and the raw materials are synthesized to obtain ethane. In this case, ethane can be obtained by a hydrogenation reaction of ethylene as a raw material, and the ethylene can also be obtained by a dehydration treatment of ethanol.
The ethane supplied from the ethane addition unit 60 is not necessarily 100% ethane. For example, the ethane concentration is higher than that of the main fuel, and by adding it to the combustion chamber 10, the mixing in the combustion chamber 10 is performed. Any substance may be used as long as it contains ethane to the extent that the content of methane is increased.

(3) In the above embodiment, the main fuel is a natural gas mainly composed of methane having a higher ignition point than ethane. However, in addition to natural gas, other hydrocarbon fuels such as gasoline and light oil are used as the main fuel. It does not matter.
When the main fuel is a hydrocarbon whose ignition point is lower than that of ethane, the opening of the ethane addition amount adjustment valve 61 is gradually increased in the cycle fluctuation suppression control. When the addition amount is increased, in the self-ignition timing control, the degree of opening of the cooling water supply amount adjustment valve 26 is gradually increased in order to prevent the retarded side shift of the self-ignition timing, and the mixture M The temperature will be adjusted to the rising side. In this case, the upper limit of the temperature of the air-fuel mixture M is the time when the opening of the cooling water supply amount adjusting valve 26 is fully opened, and is about 80 ° C., for example.

(4) In the above embodiment, when adjusting the temperature of the air-fuel mixture M taken as fresh air into the plurality of combustion chambers 10, the air-fuel mixture M is exchanged by heat exchange with the relatively high-temperature engine coolant in the heat exchanger 25. However, when the temperature of the air-fuel mixture M is relatively high due to, for example, supercharging, the air-fuel mixture is heated with the relatively low-temperature cooling water. You may comprise so that it may cool by replacement | exchange and the amount of cooling may be adjusted.

(5) In the above embodiment, the engine cooling water to the heat exchanger 25 provided in the intake passage 21 is used as the overall self-ignition timing adjusting means Y1 that can adjust the self-ignition timing of each of the plurality of combustion chambers 10 at once. A fresh air temperature adjusting means for adjusting the temperature of the air-fuel mixture M taken as fresh air into the plurality of combustion chambers 10 is provided, such as a cooling water supply amount adjusting valve 26 capable of adjusting the supply amount of In the configuration, the self-ignition timings of the plurality of combustion chambers 10 may be adjusted all at once. For example, as the overall self-ignition timing adjusting means Y1, the fresh air pressure adjusting means for adjusting the pressure of the air-fuel mixture sucked as fresh air into the plurality of combustion chambers, the exhaust gas recirculation rate (EGR rate) to the plurality of combustion chambers, An EGR rate adjusting means for adjusting, an air-fuel ratio adjusting means for adjusting the air-fuel ratio of the air-fuel mixture, an effective compression ratio adjusting means for adjusting an effective compression ratio in a plurality of combustion chambers, and the like can be adopted. In addition, each means can employ | adopt a well-known structure according to the objective.
Further, this overall self-ignition timing adjusting means Y1 may be omitted as appropriate.

(6) In the above-described embodiment, the individual self-ignition timing adjusting means Y2 that can individually adjust the self-ignition timing of each of the plurality of combustion chambers 10 serves as a spark by the spark plug 11 provided in each of the plurality of combustion chambers 10. Although the ignition circuit 12 for individually adjusting the generation timing is provided, the self-ignition timing of each of the plurality of combustion chambers 10 may be individually adjusted with another configuration. For example, as the individual self-ignition timing adjusting means Y2, a fuel injection valve arranged at each intake port of a plurality of combustion chambers can be employed. That is, by individually adjusting the fuel injection amount in each intake port by each fuel injection valve and individually adjusting the air-fuel ratio of the air-fuel mixture in the plurality of combustion chambers, the self-ignition of each of the plurality of combustion chambers The time can be adjusted individually.
The individual self-ignition timing adjusting means Y2 may be omitted as appropriate.

(7) In the above-described embodiment, the premixed compression ignition engine according to the present invention is configured as a multi-cylinder type.

  The present invention relates to a premixed compression ignition type engine in which a hydrocarbon-based main fuel is mixed with fresh air sucked into a combustion chamber to form an air-fuel mixture, and the air-fuel mixture is compressed in the combustion chamber to self-ignite and burn. And the operation control method thereof can be suitably used.

1: Premixed compression ignition engine 7: Crank angle sensor 8: In-cylinder pressure sensor 10: Combustion chamber 21: Intake passage 23: Mixer 24: Fuel supply valve 25: Heat exchanger 26: Coolant supply amount adjustment valve (fresh air) Temperature adjustment means)
31: Exhaust passage 51: Self-ignition timing detection means 52: Cycle fluctuation detection means 53: Control means 60: Ethane addition section (ethane addition means)
61: Ethane addition amount adjusting valve M: Gas mixture X: Ethane content rate adjusting means Y1, Y2: Self-ignition timing adjusting means

Claims (5)

A premixed compression ignition engine in which a hydrocarbon-based main fuel is mixed with fresh air sucked into a combustion chamber to form an air-fuel mixture, and the air-fuel mixture is compressed in the combustion chamber to self-ignite and burn.
Self-ignition timing detection means for detecting the self-ignition timing of the air-fuel mixture in the combustion chamber, and self-ignition timing adjustment means capable of adjusting the self-ignition timing of the air-fuel mixture in the combustion chamber,
Cycle content detecting means for detecting deterioration of cycle fluctuation, and ethane content rate adjusting means capable of adjusting the ethane content rate in the combustion chamber,
Performing self-ignition timing control for controlling the self-ignition timing adjustment means so that the self-ignition timing detected by the self-ignition timing detection means is maintained within a target self-ignition timing range; A premixed compression ignition type engine comprising control means for executing cycle fluctuation suppression control for controlling the ethane content rate adjusting means so that deterioration of detected cycle fluctuation is suppressed. It is configured as a multi-cylinder type with multiple combustion chambers.
The self-ignition timing adjusting means is capable of adjusting the self-ignition timing of each of the plurality of combustion chambers at once, and the individual self-adjustment capable of individually adjusting the self-ignition timing of each of the plurality of combustion chambers. The premixed compression ignition type engine according to claim 1, further comprising ignition timing adjusting means.   The premixed compression ignition type engine according to claim 1 or 2, wherein the ethane content rate adjusting means is an ethane addition means capable of adding ethane to the combustion chamber by adjusting the addition amount.   The premixed compression ignition type engine according to any one of claims 1 to 3, wherein the main fuel is natural gas mainly containing methane. Operation control method of a premixed compression ignition engine in which hydrocarbon-based main fuel is mixed with fresh air sucked into the combustion chamber to form an air-fuel mixture, and the air-fuel mixture is compressed in the combustion chamber to self-ignite and burn Because
Self-ignition timing detection means for detecting the self-ignition timing of the air-fuel mixture in the combustion chamber, and self-ignition timing adjustment means capable of adjusting the self-ignition timing of the air-fuel mixture in the combustion chamber,
Cycle content detecting means for detecting the deterioration of the cycle fluctuation, and ethane content rate adjusting means capable of adjusting the ethane content rate in the combustion chamber are provided.
Performing self-ignition timing control for controlling the self-ignition timing adjustment means so that the self-ignition timing detected by the self-ignition timing detection means is maintained within a target self-ignition timing range; An operation control method for a premixed compression ignition type engine that executes cycle fluctuation suppression control for controlling the ethane content rate adjusting means so that deterioration of detected cycle fluctuation is suppressed.

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