JP2002206441A - Premix compression self-ignition engine and starting operation method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique, capable of suctioning fresh air from a suction passage 12 to a combustion chamber 9 and smoothly conducting starting operation of a premix compression self-ignition engine 1 for making air/fuel mixture to be compressed to conduct self-ignited combustion. SOLUTION: This premix compression self-ignition engine is provided with a heating means 3 capable of heating the fresh air A, an exhaust gas re- circulation rate adjusting means 22b capable of adjusting exhaust gas re- circulation rate with respect to the fresh air A, and a starting operation means 22a for conducting a first operation for setting the exhaust gas recirculation rate as a first set value by the exhaust gas re-circulation rate adjusting means 22b as well as heating the fresh air A suctioned to the combustion chamber 9 to warm-up temperature by the heating means 3, and a second operation for setting the exhaust gas recirculation rate as a second set value larger than the first set value by the exhaust gas recirculation rate adjusting means 22b, as well as lowering a heating amount of the heating means 3, so as to start the operation based on an inputted operation start command.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premixed compression ignition engine which draws fresh air from an intake passage into a combustion chamber, compresses and ignites a mixture formed in the combustion chamber, and burns the mixture. The present invention relates to a technique for starting such a homogeneous charge compression ignition engine.

[0002]

2. Description of the Related Art Recently, the concept of a compression self-ignition engine that actively utilizes natural ignition has been attracting attention. This kind of homogeneous charge compression ignition engine is also being developed for the purpose of preventing particulates of diesel engines. The ignition type is a spontaneous ignition type using adiabatic compression, similar to a diesel engine, but instead of injecting fuel into compressed air, air (oxygen-containing) is mainly used like a spark ignition type engine. A premixed mixture of gas and fuel) is formed in the combustion chamber and spontaneously ignited and burned by compression.
Continue rotating the crankshaft. If this technique is applied to a gas engine, it is possible to increase the compression ratio and obtain high efficiency.

[0003]

However, this kind of homogeneous charge compression ignition engine has not been effective for warming up the combustion room temperature and the combustion chamber wall temperature at the time of starting operation, and has been demanded for a long time. . In a homogeneous charge compression ignition engine,
The fuel is burned using the self-ignition of the fuel by the temperature rise due to the adiabatic compression. However, the self-ignition does not surely occur unless the combustion room temperature and the combustion chamber wall temperature have reached a certain temperature. For this reason, in order to stably operate the homogeneous charge compression ignition engine at startup, it is necessary to perform a warm-up operation for a certain period of time to raise the combustion room temperature and the combustion chamber wall temperature. However, according to the internal combustion engine provided with the conventional homogeneous charge compression ignition engine described above, since there is no effective warm-up technology, it was not possible to smoothly start the homogeneous charge compression ignition engine.

Accordingly, it is an object of the present invention to provide a technique capable of solving the above-mentioned problems and smoothly starting a homogeneous charge compression ignition engine.

[0005]

Means for Solving the Problems [Configuration 1] A premixed compression ignition engine according to the present invention, as described in claim 1, adjusts a heating means capable of heating the fresh air and an exhaust gas recirculation rate. Possible exhaust gas recirculation rate adjusting means, and when the operation is started based on the input operation start command, the heating means heats the fresh air sucked into the combustion chamber to a warm-up temperature, and recycles the exhaust gas. A first operation in which the exhaust gas recirculation rate is set to a first set value by a circulation rate adjusting means; and a heating amount of the heating means is reduced, and the exhaust gas recirculation rate is set to the first value by the exhaust gas recirculation rate adjusting means. Starting operation means for performing the second operation for setting the second set value larger than the set value in the order described. The starting operation method of the homogeneous charge compression ignition engine according to the present invention is a start operation method for starting the operation of the homogeneous charge compression ignition engine, wherein the fresh air is warmed. Performing a first operation of heating the engine temperature and performing a first operation of setting the exhaust gas recirculation rate to a first set value to operate the premixed compression ignition engine;
Then, based on the detection result of the operating state of the homogeneous charge compression ignition engine, the first operation is to reduce the amount of heating of the fresh air and to increase the exhaust gas recirculation rate to a second value larger than the first set value. Switching to the second operation set to the set value and executing a second operation step of operating the homogeneous charge compression ignition engine. The exhaust gas recirculation rate in the present application is a ratio of the amount of exhaust gas recirculated to fresh air in one cycle to the capacity of the combustion chamber.

[Effects] That is, the homogeneous charge compression ignition engine of this configuration starts the operation of the engine based on an input operation start command. Works and the heating means and the exhaust gas recirculation rate adjusting means work properly to start the operation smoothly. More specifically, the start-up operation means is configured such that in the initial stage of the start-up operation, the air-fuel mixture is compressed in the combustion chamber by the heating means even in a state in which the combustion room temperature and the combustion chamber wall temperature in the premixed compression ignition engine have not reached certain temperatures. In order to be able to self-ignite, a first operation is performed in which the fresh air is heated to the warm-up temperature and the mixture formed in the combustion chamber is raised from, for example, about 50 ° C. to about 250 ° C. A first operation step is performed in which the heated air-fuel mixture is compressed and ignited and burned. Then, the starting operation means compresses the air-fuel mixture in the combustion chamber in the latter stage of the starting operation even when the combustion room temperature and the combustion chamber wall temperature decrease the heating amount of the heating means, for example, by stopping the heating means. When the temperature is raised to such an extent that ignition is possible, the first operation is switched to the second operation, and the amount of heating of the heating means is reduced, and the air-fuel mixture whose temperature has been reduced is compressed and self-ignited and burned. Perform the process.

[0007] However, the start-up operation means switches from the first operation to the second operation.
If the amount of heating of the heating means is simply reduced when switching to the operation, the temperature of the air-fuel mixture formed in the combustion chamber suddenly decreases, so that the air-fuel mixture is sufficiently compressed and self-ignited immediately after the second operation is started. In some cases, the operating state of the homogeneous charge compression ignition engine suddenly changes, causing a misfire or a shutdown. Therefore, in the premixed compression ignition engine of this configuration, exhaust gas recirculation rate adjusting means capable of adjusting the exhaust gas recirculation rate while recirculating high-temperature exhaust gas to fresh air is provided. When performing the first operation step by performing the first operation, the operating means sets the exhaust gas recirculation rate to a smaller first set value,
When the second operation step is performed by lowering the heating amount of the heating means later and performing the second operation step, the exhaust gas recirculation rate is maintained at an appropriate temperature by supplementing the reduction in the heating amount. It is configured to switch to the second set value to the extent possible. With this configuration, when the start-up operation unit starts the second operation by reducing the heating amount of the heating unit, the start-up operation unit reduces the temperature decrease of the air-fuel mixture due to the decrease in the heating amount of the heating unit, thereby reducing the exhaust gas recirculation rate. By alleviating the increase by the increase, it is possible to sufficiently compress and ignite the air-fuel mixture, and it is possible to prevent misfire or operation stop at the time of switching. Therefore, it is possible to realize a homogeneous charge compression ignition engine and a start-up operation method thereof that can smoothly start the operation by smoothly switching from the first operation step to the second operation step with a simple configuration.

[0010] According to a second aspect of the present invention, there is provided a premixed compression self-ignition engine according to the present invention, in addition to the configuration of the premixed compression self-ignition engine according to the first aspect, further comprising: However, the exhaust gas recirculation rate is adjusted by adjusting a closing timing of an exhaust valve provided in the combustion chamber to adjust an exhaust gas residual rate in the fuel chamber.

[Effect] The engine advances the closing timing of the exhaust valve with respect to the top dead center in the exhaust stroke,
Exhaust gas that was to be discharged to the exhaust passage after the exhaust valve was closed remains in the combustion chamber, and the remaining exhaust gas is recirculated to fresh air in the next intake stroke. It can be carried out. The exhaust gas recirculation rate adjusting means of the homogeneous charge compression ignition engine of this configuration adjusts the closing timing of the exhaust valve, which is advanced and closed with respect to the top dead center, so that the exhaust gas recirculated to the fresh air is adjusted. Can be configured to adjust the residual rate in the combustion chamber, that is, the exhaust gas recirculation rate. The exhaust gas recirculation rate adjusting means configured as described above can be realized with a simple configuration, and when changing the exhaust gas recirculation rate, the exhaust gas recirculation rate in the next intake stroke in which the closing timing of the exhaust valve is adjusted is adjusted. Since the adjustment is possible, the exhaust gas recirculation rate can be changed instantaneously. Therefore, when the starting operation means switches from the first operation to the second operation in the premixed compression ignition engine of this configuration, the fresh air of the heating means The recirculation rate of exhaust gas to
It is possible to change the set value to the second set value, and it is possible to prevent a malfunction or the like due to a delay in the change in the exhaust gas recirculation rate.

On the other hand, the engine retards the closing timing of the exhaust valve with respect to the top dead center in the exhaust stroke,
A part of the exhaust gas discharged to the exhaust passage is sucked into the combustion chamber again in the early stage of the intake stroke, and the exhaust gas can be recirculated in the intake stroke to recirculate the exhaust gas into fresh air. The rate adjusting means can be configured to adjust the closing timing of the exhaust valve that is closed with a delay with respect to the top dead center to adjust the exhaust gas recirculation rate. Since it is difficult to accurately adjust the amount of exhaust gas sucked into the combustion chamber again due to pulsation in the exhaust path, etc., the closing timing of the exhaust valve is configured to be advanced with respect to top dead center, It is preferable to carry out the exhaust gas recirculation while leaving the exhaust gas.

According to a third aspect of the present invention, there is provided a homogeneous charge compression ignition engine according to the present invention, wherein a heating means capable of heating the fresh air and an actual compression ratio of the combustion chamber are adjustable. Compression ratio adjusting means, and for starting operation based on the input operation start command, heating the fresh air taken into the combustion chamber by the heating means to a warm-up temperature, and by the actual compression ratio adjusting means. A first operation in which the actual compression ratio is set to a first set value; and a second setting in which the heating amount of the heating means is reduced and the actual compression ratio is larger than the first set value by the actual compression ratio adjusting means. Starting operation means for performing the second operation set to the value in the order described. The starting operation method of the homogeneous charge compression ignition engine according to the present invention is a start operation method of starting the homogeneous charge compression ignition engine based on an input operation start command. Performing a first operation step of operating the premixed compression ignition engine by performing a first operation of heating the fresh air to a warm-up temperature and setting an actual compression ratio of the combustion chamber to a first set value. Then, based on the detection result of the operating state of the premixed compression ignition engine, the first operation is to reduce the heating amount for the fresh air and to increase the actual compression ratio greater than the first set value. Switching to the second operation set to the second set value and executing a second operation step of operating the homogeneous charge compression ignition engine.

[Effects] That is, the homogeneous charge compression ignition engine of this configuration starts operation based on an input operation start command, similarly to the above-described configuration. The start-up operation means works, and the heating means and the actual compression ratio adjusting means work properly to start the operation smoothly. Specifically, the start-up operation means performs the first operation step of performing the first operation of heating the fresh air to the warm-up temperature by the heating means in the early stage of the start-up operation, and performs the first operation process step in the latter half of the start-up operation. The second operation step is performed by switching to the second operation in which the heating amount is reduced. However, when the startup operation means switches from the first operation to the second operation, if the heating amount of the heating means is simply reduced, the temperature of the air-fuel mixture formed in the combustion chamber suddenly decreases. Immediately after the start, it may not be possible to sufficiently compress and ignite the air-fuel mixture, and the operating state of the premixed compression-ignition engine may suddenly change, causing a misfire or a shutdown. Therefore, in the premixed compression ignition engine of the present configuration, the actual compression ratio adjusting means is provided, and the start-up operation means performs the first operation to perform the first operation step. When the actual compression ratio is set to a smaller first set value and the second operation step is performed by lowering the heating amount of the heating means later and then performing the second operation step, the actual compression ratio is reduced by the decrease in the heating amount. Is switched to a second set value at which the air-fuel mixture can self-ignite under compression. With this configuration, when the start-up operation unit starts the second operation by reducing the heating amount of the heating unit, the start-up operation unit removes the air-fuel mixture that has decreased to a temperature at which compression self-ignition is difficult due to the reduction in the heating amount of the heating unit. In addition, the compression self-ignition can be sufficiently performed by increasing the actual compression ratio, and misfire or operation stop at the time of switching can be prevented. Therefore, it is possible to realize a homogeneous charge compression ignition engine and a start-up operation method thereof that can smoothly start the operation by smoothly switching from the first operation step to the second operation step with a simple configuration.

[Structure 4] According to a fourth aspect of the present invention, in addition to the structure of the premixed compression self-ignition engine according to the third aspect, the actual compression ratio adjusting means may include an actual compression ratio adjusting means. And a means for adjusting a compression stroke by adjusting a closing timing of an intake valve provided in the combustion chamber to adjust the actual compression ratio.

[Effects] In the engine, the closing timing of the intake valve is retarded or advanced with respect to the bottom dead center, so that the piston is compressed from the position where the intake valve is closed to the top dead center. Only in the stroke can the air-fuel mixture be compressed. Then, the actual compression ratio adjusting means of the premixed compression self-ignition engine of this configuration adjusts the closing timing of the intake valve which is closed by being retarded or advanced with respect to the bottom dead center, and from the bottom dead center of the piston. The compression stroke ratio for all strokes up to the top dead center may be adjusted to adjust the actual actual compression ratio. The actual compression ratio adjusting means thus configured can be realized with a simple configuration and, unlike a turbocharger, can instantaneously change the actual compression ratio. When the start-up operation means switches from the first operation to the second operation in (1), the actual compression ratio is adjusted to the first value by following a decrease in the amount of heating of the heating means for fresh air.
It is possible to change the set value to the second set value, and it is possible to prevent an operation failure or the like due to a delay in the change of the actual compression ratio.

[Structure 5] A premixed compression ignition engine according to the present invention is characterized in that, in addition to the structure of the premixed compression ignition engine according to any one of the constitutions 1 to 4, the premixed compression ignition engine is provided. Operating state detecting means for detecting an operating state of the ignition engine; and the starting operation means performs the first operation when the operating state detecting means detects the operating state in which the second operation can be performed. The operation is switched to the second operation.

[Operation and Effect] The starting operation means of the homogeneous charge compression ignition engine of the present invention performs the first operation and performs the first operation step, and then switches the first operation to the second operation. Although the normal operation is performed, it is important to appropriately determine the timing of switching from the first operation to the second operation. Therefore, in the homogeneous charge compression ignition engine of the present configuration, by providing the operating state detecting means, the operating state of the homogeneous charge compression ignition engine such as the temperature in the combustion chamber, the temperature or pressure of fresh air, the temperature of exhaust gas, etc. Can be detected, and the start-up operation means changes the operation state detected by the operation state detection means to the second operation when performing the first operation and performing the first operation step. When it is detected that the air-fuel mixture can be compressed and ignited in the combustion chamber even after the switching, it is determined that the switching to the second operation is possible, and the second operation is performed to perform the second operation process. I do. Therefore, it is possible to provide a premixed compression ignition engine that can switch from the first operation step to the second operation step more smoothly and start operation with a simple configuration.

[Structure 6] According to a sixth aspect of the present invention, there is provided a homogeneous charge compression ignition engine according to the present invention, wherein the heating means includes: In the above-described intake passage, a burner device is configured to burn a burner fuel by using a part of oxygen contained in the fresh air to heat the fresh air.

[Effects] As described above, a burner device is provided as a heating means for injecting and burning burner fuel in the intake passage, and this burner fuel uses part of oxygen contained in fresh air. Then, the combustion exhaust gas is mixed into the fresh air to heat the fresh air. Further, the burner device burns the fuel for the burner by using a part of the oxygen contained in the fresh air in the intake passage. Therefore, in the combustion chamber, the fuel is compressed and self-ignited by utilizing the remaining oxygen. Will be. Therefore, the heating means can be simply configured.

When the heating means is configured as a burner device, the burner device is configured as a pulse burner for intermittently burning the burner fuel or an impact burner for ejecting and burning the burner fuel so as to collide with each other. can do. Such a pulse burner and an impact burner have a width (TDR) for changing the combustion amount.
However, since it is wider than a normal Bunsen burner, for example, it is easy to obtain an optimal combustion amount, which is convenient. Since the pulse burner intermittently burns the fuel for the burner, a wide T is obtained by changing the intermittent combustion time.
You can take DR. The impact burner ejects burner fuel from a plurality of nozzles and causes them to collide with each other, thereby generating a vortex at the collision portion and easily performing flame holding. Therefore, a wide TDR can be obtained.

[Structure 7] According to a seventh aspect of the present invention, in addition to the structure of the premixed compression self-ignition engine according to any one of the first to sixth aspects, the start-up operation means may include: , After performing the second operation,
The operation target is set to the setting target set to the second set value,
It is a means for performing a third operation for reducing the value to a third set value smaller than the second set value.

[Function and Effect] In the homogeneous charge compression ignition engine of the present invention, the first operation is performed by the start-up operation means to perform the first operation step, and then the second operation is performed to perform the second operation step. However, even after switching to the second operation, the warm-up of the homogeneous charge compression self-ignition engine gradually progresses, and if left as it is, there is a risk that the air-fuel mixture will prematurely ignite in the combustion chamber and knocking or the like will occur. is there. Therefore, as in the present configuration, after the second operation is performed by the start-up operation means, the third operation is performed, and as the warm-up progresses, the target of setting the exhaust gas recirculation rate or the actual compression ratio is set to the second setting. By continuously or stepwise decreasing the value from the value to the third set value, exhaust gas recirculation is performed in accordance with the progress of warm-up until the progress of warm-up is stopped in the second operation process and stable operation is performed. By setting the ratio or the actual compression ratio to a preferable value, the engine can be operated stably. The third set value is the value of the exhaust gas recirculation rate or the actual compression ratio when the engine is completely warmed up.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a homogeneous charge compression ignition engine 1 of the present invention will be described below with reference to the drawings. The premixed compression ignition engine 1 of the present application can heat the fresh air sucked into the combustion chamber 9, and adjust the opening / closing timing of the intake valve 6 and the exhaust valve 5 by operating the heating means 3. A variable opening / closing timing mechanism 4 is provided, and the heating unit 3 and the variable opening / closing timing mechanism 4 are respectively controlled by the control device 22.

The homogeneous charge compression ignition engine 1 is provided with a cylinder 7 having an intake valve 5 and an exhaust valve 6, and a piston 8 housed in the cylinder 7.
The space formed between the cylinder 7 and the piston 8 is a combustion chamber 9. The piston 8 is connected to the crankshaft 11 by a connecting rod 10, and the reciprocating motion of the piston 8 is obtained by the connecting rod 10 as a rotational movement of the crankshaft 11. With this configuration, the air-fuel mixture as fresh air in the intake passage 12 is sucked into the combustion chamber 9 via the intake valve 5, passes through the compression and expansion strokes, and then the exhaust gas flows to the exhaust passage 13 via the exhaust valve 6. Exhausted.

The homogeneous charge compression ignition engine 1 is provided with a mixer 15. The mixer 15 supplies a fuel G, which is a natural gas, to an air A supplied from an upstream side by a shutoff valve 21 and a flow control valve 20. Through the intake passage 12
The air-fuel ratio of the formed air-fuel mixture is adjusted by controlling the flow control valve 20 by the control device 22. The air-fuel mixture formed by the mixer 15 is drawn into the combustion chamber 9 from the intake passage 12.

The operation cycle of the homogeneous charge compression ignition engine 1 is configured as a four-cycle engine which completes one cycle through an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. Usually, in the four-stroke engine, in the intake stroke, only the intake valve 5 is opened, and the intake path 1
The air-fuel mixture in 2 is sucked. In the compression stroke,
The intake valve 5 and the exhaust valve 6 are both closed, the piston 8 moves in a direction to reduce the volume of the combustion chamber 9, and the air-fuel mixture is compressed in the combustion chamber 9. The position of the piston in a state where the compression is completed is called a top dead center, and the compression self-ignition of the air-fuel mixture in the premixed compression self-ignition engine 1 is as follows.
This occurs when the piston 8 is located near this position. The expansion stroke is a stroke in which the piston 8 moves in a direction to increase the volume of the combustion chamber 9 by high-pressure gas generated by combustion. Even during this process, the intake valve 5 and the exhaust valve 6 are both closed. Further, in the exhaust stroke, only the exhaust valve 6 is opened, and the exhaust gas in the combustion chamber 9 is discharged as the piston 8 moves in a direction to reduce the space in the combustion chamber 9. Basically, the homogeneous charge compression ignition engine 1 also differs from other engines in that the ignition mode is such that the premixed gas is compressed and the premixed gas is spontaneously ignited by the heat generated by the adiabatic compression. There is no place. The specifications of the homogeneous charge compression ignition engine 1 of this embodiment are as follows: the cylinder bore diameter is 110 mm, the stroke of the piston 8 is 106 mm, and the compression ratio is 18. The air-fuel mixture of about 0.3 is compressed, self-ignited and burned, and the crankshaft 11 is rotated at a rotational speed of about 1200 ppm.

Further, the homogeneous charge compression ignition engine 1
A burner device 14 is provided as the heating means 3, and details of the burner device 14 will be described with reference to FIGS. 1 and 2. As shown in FIG. 2, the burner device 14
Are burned out so as to collide with each other so as to enhance the flame holding. This is an impact burner that can take a large change rate (TDR) of the combustion amount. The burner device 14 defines a burner combustion chamber 49 whose both ends are throttled, and has a cylindrical body 43 having an inlet 45 and an outlet 44 at both ends, a flange 42 on the outer periphery of the inlet 45, and a discharge port 44. A flange 41 is provided on the outer peripheral portion. The flange 42 is connected to the side where the air A flows in the internal combustion engine 1, and the flange 41 is connected to the mixer 15 and the homogeneous charge compression ignition engine 1.

Further, the burner device 14 includes a control device 22
Member 46 for guiding the fuel G to the burner combustion chamber 49 via the flow control valve 19 controlled by the burner nozzle 4 at the end of the pipe member 46 in the burner combustion chamber 49.
6a, and a sparklot 48 that generates a spark near the ejection direction of the burner nozzle 46a. And
The control device 22 causes the flow rate control valve 19 to operate to cause the fuel G to be ejected from a plurality of injection holes (not shown) provided in the burner nozzle 46 into the burner combustion chamber 49 while causing the fuel G to collide with each other, and also causes the spark lot 48 to operate. By igniting the fuel G ejected from the lever, it is possible to burn the fuel G in the burner combustion chamber 49 with a compact flame. The burner device 14 burns the fuel G using a part of the oxygen contained in the air A flowing through the intake passage 12, and mixes the high-temperature combustion exhaust gas with the heated air A into the outlet 4.
4 to the intake path 12. In addition, such an impact burner has better flame holding properties than a normal burner, for example, a Bunsen burner, and has a large width (TDR) in which the amount of combustion can be changed, so that it is easy to obtain an optimal amount of combustion. Further, the burner combustion chamber 49 is provided with a flame lot 47. The flame in the burner combustion chamber 49 is detected and output to the control device 22 to check whether the burner device 14 is operating normally. .

Further, the homogeneous charge compression ignition engine 1
Exhaust gas recirculation rate adjusting means 22 provided in control device 22
b or the opening / closing timing variable mechanism 4 controlled by the actual compression ratio adjusting means 22c, and a control method thereof will be described. The exhaust gas recirculation rate adjusting means 22 b adjusts the exhaust gas recirculation rate of exhaust gas recirculated to the air-fuel mixture taken into the combustion chamber 9, and closes the exhaust valve 5 provided in the combustion chamber 9. This is means for adjusting the exhaust gas recirculation rate by adjusting the exhaust gas residual rate in the fuel chamber 9 by timing adjustment. That is, in the exhaust stroke of the homogeneous charge compression ignition engine 1, the closing timing of the exhaust valve 5 is advanced to the top dead center, so that the exhaust valve 5 is discharged to the exhaust path after the exhaust valve 5 is closed. A part of the exhaust gas which should have been left in the combustion chamber 9 can be recirculated to fresh air in the next intake stroke.
b is configured to adjust the closing timing of the exhaust valve 5, which is closed by being advanced with respect to the top dead center, to adjust the residual rate of the exhaust gas in the combustion chamber 9, that is, the exhaust gas recirculation rate. ing.

The actual compression ratio adjusting means 22c is for adjusting the actual actual compression ratio of the combustion chamber 9, and by adjusting the closing timing of the intake valve 6 provided in the combustion chamber 9, the full stroke of the piston 8 is adjusted. This is a means for adjusting the actual compression ratio by adjusting the compression stroke rate with respect to. That is, by making the closing timing of the intake valve 6 retard or advance with respect to the bottom dead center, the piston 8 can move only during the compression stroke from the position where the intake valve 6 is closed to the top dead center. The air-fuel mixture cannot be compressed, and the actual compression ratio adjusting means 22c operates the intake valve 6 that is closed by being retarded or advanced with respect to the bottom dead center.
Is adjusted so as to adjust the compression stroke ratio for the entire stroke from the bottom dead center to the top dead center of the piston 8, thereby adjusting the actual actual compression ratio.

Further, the control device 22 of the homogeneous charge compression ignition engine 1 is provided with start-up operation means 22a for starting the operation of the homogeneous charge compression ignition engine 1.
The start-up operation unit 22a controls the heating unit 3 and at least one of the exhaust gas recirculation rate adjustment unit 22b and the actual compression ratio adjustment unit 22c to control the premixed compression ignition engine 1
Is configured to perform the start-up operation.

[Embodiment 1] Next, a start-up operation method of the homogeneous charge compression ignition engine 1 when the start-up operation means 22a controls the exhaust gas recirculation rate adjusting means 22b will be described along the flow. First, an operation start command is input to the control device 22 before the operation of the homogeneous charge compression ignition engine 1 is started. However, at that time, especially the combustion chamber wall 9a of the premixed compression ignition engine 1 is still at a low temperature, and even when the premixed gas at room temperature is supplied as in the normal operation, the compression ignition cannot be completely performed.

Therefore, in the homogeneous charge compression ignition engine 1 of the present invention, the starting operation means 22a of the control device 22
However, after the operation start command is input, the burner device 14 is operated while the crankshaft 11 is rotated at about 500 to 1200 rpm by the cell motor 23 to supply high-temperature combustion exhaust gas to the mixer 15 and the combustion chamber 9 side. hand,
The homogeneous charge compression ignition engine 1 is warmed up. Such warm-up is performed until the temperature in the intake passage 12 detected by the temperature sensor 16, that is, the temperature flowing through the intake passage 12 rises to a predetermined value, for example, about one minute. In this embodiment, the burner device 14 supplies the burner fuel G with:
Using a part of oxygen in the intake passage 12, an equivalent ratio of 0.1 to
The temperature of the air A in which the combustion exhaust gas is mixed in the intake passage 12 is about 200 to 250 ° C.

Next, the starting operation means 22a of the control device 22
Performs the first operation of heating the air-fuel mixture to the warm-up temperature by the heating means 3 and setting the exhaust gas recirculation rate to the first exhaust gas recirculation rate (first set value) by the exhaust gas recirculation rate adjusting means 22b. That is, the start-up operation unit 22a uses the heating unit 3 to heat the air-fuel mixture to the warm-up temperature in the first operation.
With the burner device 14 operating, the fuel G is supplied to the mixer 15 by operating the flow control valve 20, and the fuel G is supplied to the heated air A mixed with the combustion exhaust gas of the intake passage 12 and heated. For example, a heated air-fuel mixture having an equivalent ratio of about 0.3 is formed at 12. Then, the heated air-fuel mixture is sucked into the combustion chamber 9 from the intake passage 12. At this time,
The start-up operation unit 22a controls the amount of combustion in the burner device 14 while detecting the temperature of the air-fuel mixture with the temperature sensor 16 or the like, and reduces the temperature of the air-fuel mixture taken into the combustion chamber 9 by 50 ° C.
The warm-up temperature is set in the range of about 250 ° C to about 250 ° C, preferably about 150 ° C to 200 ° C. Further, the starting operation means 2
2a adjusts the closing timing of the exhaust valve 5 by the exhaust gas recirculation rate adjusting means 22b to set the exhaust gas recirculation rate to the first exhaust gas recirculation rate by the exhaust gas recirculation rate adjusting means 22b. The ratio of the remaining exhaust gas, that is, the exhaust gas recirculation rate is set to, for example, about 6% as the first exhaust gas recirculation rate. Since the heated air-fuel mixture is supplied to the combustion chamber 9 by performing the first operation by the start-up operation means 22a in this manner, even if the combustion chamber wall 9a is still in a low temperature state, this combustion is performed in the combustion chamber 9. The mixture can be compressed and self-ignited and burnt, while maintaining the rotation of the crankshaft 11.
The warm-up operation of the homogeneous charge compression ignition engine 1 can be performed, and such a process is referred to as a first operation process.

Next, the starting operation means 22a of the control device 22
Means that the heating amount of the heating means 3 is reduced and the exhaust gas recirculation rate is set to a second exhaust gas recirculation rate (second set value) larger than the first exhaust gas recirculation rate by the exhaust gas recirculation rate adjusting means 22b. Perform two operations. That is, the starting operation means 2
2a, in order to reduce the heating amount of the heating means 3 in the second operation, the combustion amount of the burner device 14 is gradually reduced until the burner device 14 stops. Then, the temperature of the air-fuel mixture in the intake path 12 gradually decreases. Therefore, the starting operation means 22a sets the exhaust gas recirculation rate to the second exhaust gas recirculation rate larger than the first exhaust gas recirculation rate by the exhaust gas recirculation rate adjusting means 22b.
The closing timing of the exhaust valve 5 is adjusted by b to gradually increase the exhaust gas recirculation rate from the first exhaust gas recirculation rate to, for example, about 20% to 30% as the second exhaust gas recirculation rate. By performing the second operation after the first operation by the start-up operation means 22a in this manner, even if the temperature of the air-fuel mixture taken into the combustion chamber 9 from the intake passage 12 decreases, the exhaust gas recirculation rate can be increased. By increasing the amount of high-temperature exhaust gas recirculated to the air-fuel mixture in the combustion chamber 9, the air-fuel mixture can be compressed and ignited and burned in the combustion chamber 9, and the premixed compressed air in a state where the burner device 14 is stopped. The process can smoothly shift to the steady operation of the ignition engine 1, and such a process is referred to as a second operation process. In the present embodiment,
Since the heating means 3 is configured as a burner device 14 and heats the air-fuel mixture by mixing high-temperature combustion exhaust gas into the air-fuel mixture sucked into the combustion chamber 9, the second operation step is performed in the first operation step. Like exhaust gas recirculation in the operating process,
Exhaust gas is mixed in the air-fuel mixture, and the mixing ratio of the exhaust gas is 20% or more, which is the same as in the second operation step.
It is about 30%. Therefore, even if the first operation step is switched to the second operation step, the ratio of the exhaust gas supplied to the air-fuel mixture is kept substantially constant, which also results in the combustion state in the combustion chamber 9. Can be stabilized.

As described above, the start-up operation means 22a of the homogeneous charge compression ignition engine 1 performs the first operation and performs the first operation step, so that the combustion chamber wall 9a and the like are sufficiently warmed up. Even if the second operation is performed by performing the second operation, the first operation is switched to the first operation when the operating state of the premixed compression ignition engine 1 is detected to such an extent that the air-fuel mixture can be compressed and ignited in the combustion chamber. Switch to 2 operation. That is, the exhaust path 13 of the homogeneous charge compression ignition engine 1 is provided with a temperature sensor 17 (an example of an operation state detecting means) for detecting the temperature of the exhaust gas discharged from the combustion chamber 9.
It is configured to detect the exhaust gas temperature as the operating state of the homogeneous charge compression ignition engine 1 and output the detection result to the control device 22. Then, the starting operation means 22a
When the temperature of the exhaust gas detected by the temperature sensor 17 is low, the temperature of the combustion chamber wall 9a is still low and the second
The first operation is continued when it is determined that the air-fuel mixture cannot be sufficiently compressed and ignited in the combustion chamber 9 even when the operation is performed, and when the exhaust gas temperature reaches a predetermined value of, for example, about 250 ° C., The second operation process is started after switching to the second operation.

In the homogeneous charge compression ignition engine 1 in which the second operation process has been started as described above, the warm-up may proceed even after that, and the start-up operation means 22a of the present embodiment uses this warm-up operation. The exhaust gas recirculation rate adjusting means 22b can be adjusted according to the progress. That is, after performing the second operation, the startup operation means 22a changes the exhaust gas recirculation rate set to the second exhaust gas recirculation rate to the exhaust gas when the premixed compression ignition engine 1 is completely warmed up. The third operation of reducing the third exhaust gas recirculation rate (third set value), which is the recirculation rate, is performed, and the operating state of the homogeneous charge compression ignition engine 1 can be stabilized.

[Embodiment 2] Next, a start-up operation method of the homogeneous charge compression self-ignition engine 1 when the actual compression ratio adjusting means 22c is controlled by the start-up operation means 22a will be described along the flow. In the homogeneous charge compression ignition engine 1 of the present invention, after the operation start command is input,
Similarly to the first embodiment, the burner device 14 is operated while the crankshaft 11 is rotated by the cell motor 23 to supply the combustion exhaust gas to the combustion chamber 9 to warm up the homogeneous charge compression ignition engine 1.

The starting operation means 22 of the control device 22
In a, the first operation is performed in which the air-fuel mixture is heated to the warm-up temperature by the heating means 3 and the actual compression ratio is set to the first actual compression ratio (first set value) by the actual compression ratio adjusting means 22c. That is,
The start-up operation means 22a includes the first
In operation, the air-fuel mixture sucked into the combustion chamber 9 by the heating means 3 is heated to a warm-up temperature. Furthermore, the starting operation means 22
a sets the actual compression ratio to the first actual compression ratio by the actual compression ratio adjustment unit 22c, adjusts the closing timing of the intake valve 6 by the actual compression ratio adjustment unit 22c, and adjusts the compression stroke of the piston 8; The actual compression ratio is adjusted to the first actual compression ratio. Also,
In the present embodiment, the first actual compression ratio is set lower than the compression ratio when the piston 8 compresses in the entire stroke by closing the intake valve 6 sufficiently slowly with respect to the bottom dead center position. You. By performing the first operation by the start-up operation means 22a in this manner, the warm-up operation of the homogeneous charge compression ignition engine 1 can be performed, and such a process is referred to as a first operation process.

Next, the starting operation means 22a of the control device 22
The time when the temperature of the exhaust gas detected by the temperature sensor 17 reaches a predetermined value of, for example, about 250 ° C. during the first operation and the first operation step, as in the first embodiment. Then, the heating amount of the heating unit 3 is reduced, and the actual compression ratio is set to the second actual compression ratio (second set value) larger than the first actual compression ratio by the actual compression ratio adjusting unit 22c.
Driving. That is, the startup operation means 22a gradually reduces the combustion amount of the burner device 14 until the burner device 14 stops in order to reduce the heating amount of the heating means 3 in the second operation. Then, the temperature of the air-fuel mixture in the intake path 12 gradually decreases. Therefore, the starting operation means 22a sets the actual compression ratio to the second actual compression ratio larger than the first actual compression ratio by the actual compression ratio adjustment means 22c.
The closing timing of the intake valve 5 is adjusted by 2c, and the actual compression ratio is gradually increased from the first actual compression ratio to the second actual compression ratio, which is about the compression ratio when the piston 8 compresses in the entire stroke. . By performing the second operation after the first operation by the start-up operation means 22a in this manner, even if the temperature of the air-fuel mixture taken into the combustion chamber 9 from the intake passage 12 decreases, the actual compression ratio is increased to increase the combustion. By sufficiently compressing the air-fuel mixture in the chamber 9, the air-fuel mixture can be compressed and self-ignited in the combustion chamber 9, and the second operation of the premixed compression-ignition engine 1 in a state where the burner device 14 is stopped. The process can smoothly shift to the process, and such a process is referred to as a second operation process.

Also, in the second embodiment, after the second operation, the start-up operation means 22a sets the actual compression ratio set to the second actual compression ratio to the value obtained by the premixed compression auto-ignition engine 1 completely. The actual compression ratio when the engine is warmed up
The third operation of reducing the actual compression ratio (third set value) is performed, so that the operating state of the homogeneous charge compression ignition engine 1 can be stabilized.

Alternative Embodiment <1> As a fuel that can be used for the premixed compression ignition engine of the present application, city gas is suitable, but any fuel such as gasoline, propane, methanol, and hydrogen is used. be able to.

<2> The air-fuel mixture formed in the combustion chamber is a mixture of fuel and an oxygen-containing gas containing oxygen for burning the fuel. For example, air is used as the oxygen-containing gas. Is common.

<3> In the above embodiment,
Although described in relation to a so-called four-stroke engine, the present application is applicable to a two-stroke engine.

<4> In the above embodiment, the air mixture is formed in the combustion chamber 9 by the air A in the mixer 15.
And the fuel G are mixed, and the air-fuel mixture formed in the intake passage 12 is sucked into the combustion chamber 9. However, a separate fuel injection valve for directly injecting fuel into the combustion chamber is provided, and It is also possible to adopt a configuration in which only air is taken in, and fuel is injected at the beginning of the intake stroke or the compression stroke to form an air-fuel mixture in the combustion chamber, and this pre-mixed air is compressed to self-ignite.

<5> In the above embodiment, in the case where a turbo-type supercharger for supercharging fresh air in the intake passage 12 using kinetic energy of exhaust gas discharged to the exhaust passage 13 is provided, The operation state of the turbocharger is such that the supercharging pressure is gradually increased from the initial stage of the start-up with the elapse of the operation start, in other words, with the elapse of warm-up. The starting operation means of the compression self-ignition engine is changed to a heating amount of fresh air by the heating means 3 and an exhaust gas set by the exhaust gas recirculation rate adjusting means 22a in consideration of an increase in the supercharging pressure of the turbocharger. The recirculation rate, or the actual compression ratio or the like set by the actual compression ratio adjusting means 22c,
It is preferable that the homogeneous charge compression ignition engine 1 be controlled so that the operating state of the engine 1 becomes stable.

<6> In addition to the temperature sensor 17 for detecting the temperature of the exhaust gas, a pressure sensor for detecting the pressure in the combustion chamber 9 and the combustion chamber wall 9a
Temperature sensor for detecting the temperature of the air, a temperature sensor for detecting the temperature of cooling water for cooling the cylinder 7 and the like, and a sensor for detecting the temperature or pressure of fresh air when a turbo-type supercharger is provided. It can be. Then, the start-up operation means switches the operation state of the homogeneous charge compression ignition engine detected by these sensors to the second operation during the first operation step by the first operation, and switches the operation state to the second operation step. At the time when the second operation step can be performed, the second operation step is performed by switching to the second operation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a homogeneous charge compression ignition engine showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a burner device provided in the homogeneous charge compression ignition engine shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Premixed compression ignition engine 3 Heating means 4 Variable opening / closing timing mechanism 5 Intake valve 6 Exhaust valve 7 Cylinder 8 Piston 9 Combustion chamber 9a Combustion chamber wall 10 Connecting rod 11 Crankshaft 12 Intake path 13 Exhaust path 14 Burner device 16 Temperature sensor 17 Temperature sensor (operating state detecting means) 22 Controller 22a Start-up operating means 22b Exhaust gas recirculation rate adjusting means 22c Actual compression ratio adjusting means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 19/10 F02D 19/10 21/08 301 21/08 301A 41/06 370 41/06 370 F02M 21 / 02 F02M 21/02 LU 25/07 510 25/07 510B 570 570J 31/04 31/04 J (72) Inventor Koji Moriya Inside Osaka Gas Co., Ltd. 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka (72) Inventor Takahiro Sako 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Inventor Masashi Nishigaki 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka In-house F term (reference) 3G023 AA02 AA06 AA08 AB05 AC01 AC06 AC07 AF02 AF03 AG03 AG05 3G062 BA09 3G092 AA11 AA12 AA17 AB07 AB08 DA08 DC08 DD03 DE15Y DF01 EA01 EA03 EA04 EA12 EA29 FA16 FA31 GA01 GA02 HA04Z HD01Z HE01Z HE08Z 3G301 HA13 HA14 HA19 HA22 JA03 JA11 JA12 JA22 KA01 KA02 KA05 LA07 LB11 LC01 NE12 PA10Z PD11Z PE01Z PE08Z PE10Z PF16Z

Claims (9)

[Claims] 1. A premixed compression ignition engine that draws fresh air from an intake passage into a combustion chamber, compresses and ignites a mixture formed in the combustion chamber, and burns the mixture, wherein the fresh air can be heated. Heating means, exhaust gas recirculation rate adjusting means capable of adjusting the exhaust gas recirculation rate, and starting operation based on the input operation start command.
Heating the fresh air taken into the combustion chamber to a warm-up temperature by the heating means and setting the exhaust gas recirculation rate to a first set value by the exhaust gas recirculation rate adjusting means;
An operation and a second operation of reducing the heating amount of the heating means and setting the exhaust gas recirculation rate to a second set value larger than the first set value by the exhaust gas recirculation rate adjusting means. A homogeneous charge compression ignition engine having a start-up operation means for performing the operation. 2. The means for adjusting the exhaust gas recirculation rate by adjusting the exhaust gas residual rate in the fuel chamber by adjusting the closing timing of an exhaust valve provided in the combustion chamber. The premixed compression ignition engine according to claim 1, wherein: 3. A premixed compression ignition engine which draws fresh air from an intake passage into a combustion chamber, compresses and ignites a mixture formed in the combustion chamber, and burns the mixture, wherein the fresh air can be heated. Heating means, actual compression ratio adjusting means capable of adjusting the actual compression ratio of the combustion chamber, and starting operation based on the input operation start command.
A first operation of heating the fresh air sucked into the combustion chamber by the heating means to a warm-up temperature and setting the actual compression ratio to a first set value by the actual compression ratio adjusting means; Starting operation means for reducing the heating amount and setting the actual compression ratio to a second set value larger than the first set value by the actual compression ratio adjusting means in the order described. Mixed compression self-ignition engine. 4. The actual compression ratio adjusting means according to claim 3, wherein the actual compression ratio adjusting means adjusts a compression stroke by adjusting a closing timing of an intake valve provided in the combustion chamber to adjust the actual compression ratio. Premixed compression ignition engine. 5. An operating state detecting means for detecting an operating state of the homogeneous charge compression ignition engine, wherein the starting operating means detects the operating state in which the second operation can be performed by the operating state detecting means. When you do
The homogeneous charge compression ignition engine according to any one of claims 1 to 4, which is a means for switching the first operation to the second operation. 6. The heating device according to claim 1, wherein
The premixed compression ignition engine according to any one of claims 1 to 5, wherein the burner device heats the fresh air by burning a burner fuel using a part of oxygen contained in the fresh air. . 7. The starting operation means, after performing the second operation, performs the second operation to change a setting target set to the second set value to a third target smaller than the second set value. The homogeneous charge compression ignition engine according to any one of claims 1 to 6, which is means for performing a third operation for reducing the set value to a set value. 8. A premixed compression ignition engine in which fresh air is sucked into a combustion chamber from an intake passage, and a mixture formed in the combustion chamber is compressed and ignited to burn the mixture, based on an input operation start command. A starting operation method for starting operation of the homogeneous charge compression ignition engine, wherein the first operation is performed by heating the fresh air to a warm-up temperature and setting an exhaust gas recirculation rate to a first set value. A first operation step of operating the homogeneous charge compression ignition engine is executed, and thereafter, the first operation is reduced based on a result of detection of an operation state of the homogeneous charge compression ignition engine, and a heating amount of the fresh air is reduced. And switching to the second operation in which the exhaust gas recirculation rate is set to a second set value larger than the first set value, and executing a second operation step of operating the premixed compression ignition engine. Ignition Start-up operation method of the gin. 9. A premixed compression ignition engine which draws fresh air from an intake passage into a combustion chamber and compresses and ignites an air-fuel mixture formed in the combustion chamber based on an input operation start command. A startup operation method of heating the fresh air to a warm-up temperature and performing a first operation of setting an actual compression ratio of the combustion chamber to a first set value to perform the premixed compression ignition engine. A first operation step of operating is performed, and thereafter, based on a detection result of an operation state of the homogeneous charge compression ignition engine, the first operation is performed by reducing a heating amount for the fresh air and reducing the actual compression ratio. A start-up operation method for a homogeneous charge compression ignition engine that switches to a second operation that is set to a second set value larger than the first set value and executes a second operation step of operating the homogeneous charge compression ignition engine.