JP2008240547A - Engine ignition control device - Google Patents

Abstract

An engine ignition control device capable of greatly improving thermal efficiency and greatly reducing exhaust emission is provided.
In an engine ignition control device, a radical generating means 11 capable of generating radicals is provided in a combustion chamber 21 and the mixture is ignited after generating radicals in the combustion chamber 21 during operation in the radical generation operation region. In addition, it has radical control means 70 for adjusting radical generation by the radical generation means 11 based on the engine operating state during operation in the radical generation operation region.
[Selection] Figure 1

Description

  The present invention relates to an engine ignition control device that ignites an air-fuel mixture after generating radicals in a combustion chamber during operation in a radical generation operation region.

The device described in Patent Document 1 includes an ozone generator that is disposed in an intake pipe and generates ozone by silent discharge. This ozone generator supplies an appropriate amount of ozone into the cylinder according to the operating conditions to improve the thermal efficiency and reduce the exhaust emission.
JP-A-5-256218

  However, the above-described conventional apparatus supplies ozone into the cylinder, but the effect obtained is small because ozone is not very high in chemical activity.

  The present invention has been made paying attention to such conventional problems, and an object of the present invention is to provide an engine ignition control device capable of greatly improving thermal efficiency and greatly reducing exhaust emission. .

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention is provided with radical generating means (11) capable of generating radicals in a combustion chamber (21), and during operation in the radical generation operation region, after generating radicals in the combustion chamber (21), the mixture is ignited. An engine ignition control device that includes a radical control means (70) for adjusting radical generation by the radical generation means (11) based on an engine operating state during operation in a radical generation operation region. .

  According to the present invention, the air-fuel mixture is ignited after generating radicals. Radicals have a higher chemical activity than ozone. By adjusting the generation of such radicals based on the engine operating conditions, the engine lean combustion operating range can be expanded, the thermal efficiency can be greatly improved, the exhaust emission can be greatly reduced, and the fuel efficiency can be reduced. Can be improved.

Hereinafter, the best mode for carrying out the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a first embodiment of an engine ignition control device according to the present invention, FIG. 1 (A) is a longitudinal sectional view, and FIG. 1 (B) is an enlarged view of a discharge electrode of FIG. 1 (A). FIG. 1 and FIG. 1C are bottom views of FIG.

  The engine ignition control device 10 includes a discharge electrode 11 and a short pulse high voltage generator 12.

  Discharge electrode 11 is arranged to open to the ceiling of combustion chamber 21 of engine 20. The engine configuration is the same as a normal one. That is, the combustion chamber 21 is formed by the cylinder head 22, the cylinder block 23, and the piston 24. The cylinder head 22 is formed with an intake port 22a and an exhaust port 22b. A fuel injector 25 is provided in the intake port 22a. The intake port 22a is opened and closed by an intake valve 51 that responds to engine rotation. The exhaust port 22b is opened and closed by an exhaust valve 61 that responds to engine rotation.

  When a short pulse high voltage is applied to the discharge electrode 11, the discharge electrode 11 generates a corona discharge by a low temperature plasma to generate a radical. Thereafter, arc discharge is generated by thermal plasma. As shown in FIG. 1B, the discharge electrode 11 has a center electrode 11a having a protrusion and a side electrode 11b formed in a cylindrical shape around the center electrode 11a, and both electrodes are insulated by an insulator 11c. The When the discharge electrode 11 undergoes corona discharge, a multi-branch streamer is generated over a wide range between the center electrode 11a and the side electrode 11b to generate radicals.

  Here, the discharge mode when a voltage is applied to the discharge electrode 11 will be described.

  When a high voltage is applied to the discharge electrode 11, electrons are released from the negative electrode (the side electrode 11b in this embodiment) and accelerated toward the positive electrode (the center electrode 11a in this embodiment). On the way, the electrons collide with the atmospheric gas, ionize the atmospheric gas, and further generate free electrons (this phenomenon is called “electron avalanche”). Free electrons immediately go to the positive electrode, but large positive ions are left behind. Further, an avalanche of electrons is induced by the potential difference generated between the positive ion group and the negative electrode, and a plasma (low temperature plasma) called positive streamer mixed with positive ions and electrons is generated. The discharge form in which the streamer is generated is called corona discharge.

  In this embodiment, the center electrode 11a is a positive electrode and the side electrode 11b is a negative electrode. However, the center electrode 11a may be a negative electrode and the side electrode 11b may be a positive electrode.

  The short pulse high voltage generator 12 includes a pulse generator 12 a and a high voltage generator 12 b and applies a short pulse high voltage to the discharge electrode 11. The application voltage, application time, and application (ignition) timing of the short pulse high voltage are controlled by the controller 70. The controller 70 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 70 may be composed of a plurality of microcomputers.

  According to such an engine ignition control device, the amount of radicals and radical distribution can be controlled.

  In order to control the amount of radicals, the number of discharges N for generating radicals and the discharge voltage Vc are adjusted. As shown in FIG. 2 (A-1), when the number of discharges N is increased, the amount of radical generation is increased. Further, as shown in FIG. 2A-2, when the discharge voltage Vc is increased, the amount of radicals generated by one discharge increases.

  Further, in order to control the radical distribution, the discharge interval τ between the radical generation discharge timing and the ignition discharge timing is adjusted as shown in FIG. Further, the stronger the gas flow, the more the radicals exist at a position away from the discharge electrode, and the weaker the gas flow, the more the radicals exist near the discharge electrode. Therefore, by adjusting the discharge interval τ and the gas flow, the degree of radical distribution and the location of radicals can be controlled almost independently. In order to control the gas flow, for example, the opening of a tumble control valve or a swirl control valve is adjusted.

  The above relationships are graphed in FIGS. 2B-1 to 2B-4. That is, as shown in FIG. 2 (B-1), the amount of radicals increases almost in proportion to the number N of discharges for radical generation. Further, as shown in FIG. 2 (B-2), the amount of radicals increases substantially in proportion to the discharge voltage Vc for generating radicals. Further, as shown in FIG. 2 (B-3), the radical distribution becomes smaller as the discharge interval τ becomes longer, and the tendency becomes larger as the gas flow becomes stronger. Furthermore, as shown in FIG. 2 (B-4), the position of the radical is such that the longer the discharge interval τ is, the longer the gas flow is, and the longer the discharge interval τ is, the longer the discharge interval τ is. After leaving the discharge electrode and passing it, the discharge electrode approaches the discharge electrode as the discharge interval τ becomes longer.

  FIG. 3 is a control map of the engine ignition control device.

  The engine ignition control device of the present invention controls the radical amount and radical distribution based on the control map of FIG. A specific control map is assigned to the engine speed Ne and the target torque T through experiments and stored in the ROM in advance.

  Here, the basic concept of the control map will be described.

  In order to improve the fuel consumption of the engine, it is preferable to expand the lean combustion operation region by, for example, making the air-fuel ratio lean or diluting with EGR. By doing so, the specific heat ratio increases and the pump loss decreases, so that the thermal efficiency can be increased.

  However, when the engine lean combustion operation region is expanded, the combustion becomes slow due to the fact that the lower the engine speed Ne, the smaller the turbulence intensity.

  Therefore, in the present invention, as shown in FIG. 3A, in the operating range where the lean limit is expanded, the amount of radicals is increased so that the amount of air-fuel mixture to be activated increases as the engine speed Ne decreases.

  Further, when the engine speed Ne is equal to or lower than a predetermined value and the engine load is equal to or higher than a predetermined value, knocking is likely to occur due to self-ignition of the end gas.

  Therefore, in the present operation range, the present invention controls the distribution of the activated air-fuel mixture to increase as the engine speed Ne decreases, as shown in FIG. Increased burning speed. In addition, by controlling the gas flow, radicals exist in the end gas part different from the discharge part. In this way, knocking is prevented.

  FIG. 4 is a diagram illustrating the operation of the present invention.

  In the present embodiment, first, radical generating discharge is performed as shown in FIG. The radical R generated by this discharge travels to the end gas portion in a tumble flow as shown in FIG. 4 (B-1) → FIG. 4 (B-2) → FIG. 4 (B-3). Then, at the timing of FIG. 4 (B-3), as shown in FIG. 4 (A-2), discharge for mixture gas ignition is performed. As described above, the discharge interval τ is a map assigned to the rotational speed and flow strength (flow strength by flow strengthening means provided in the intake port such as a tumble control valve or a swirl control valve or valve opening control of the intake valve). Set based on.

  When the engine lean combustion operating range is expanded, the lower the engine speed Ne, the lower the turbulence intensity, resulting in slower combustion. Therefore, in this embodiment, a discharge electrode that generates radicals by corona discharge is used, and the amount of radicals is increased so that the amount of air-fuel mixture to be activated increases as the engine speed Ne decreases. Since it did in this way, stable combustion is attained even if it expands the engine lean combustion operation range.

  Further, when the engine speed Ne is equal to or lower than a predetermined value and the engine load is equal to or higher than a predetermined value, knocking is likely to occur due to self-ignition of the end gas. Therefore, in the present embodiment, in such an operating region, the combustion speed in the latter half of combustion is increased by controlling the activated air-fuel mixture distribution to be larger as the engine speed Ne is smaller. In addition, by controlling the gas flow, radicals exist in the end gas part different from the discharge part. As a result, knocking could be prevented.

(Second Embodiment)
FIG. 5 is a view showing a variable valve mechanism used in the second embodiment of the engine ignition control apparatus according to the present invention.

  In the following embodiments, the same reference numerals are given to the portions that perform the same functions as those of the above-described embodiments, and overlapping descriptions are omitted as appropriate.

  As shown in FIG. 8A, the engine of the present embodiment adjusts the intake air amount by controlling the opening of the intake throttle in the high load range, but closes the intake valve 51 in the low load range. The intake air amount is adjusted by controlling the advance / retard of (IVC).

  In order to control the closing timing of the intake valve 51, for example, a variable valve mechanism disclosed in JP-A-11-107725 may be used. Here, the variable valve mechanism will be briefly described with reference to FIG.

  The variable valve mechanism 200 includes a cam shaft 210, a link arm 220, a valve lift control shaft 230, a rocker arm 240, a link member 250, and a swing cam 260. The valve 51 is opened and closed.

  The camshaft 210 is rotatably supported on the cylinder head along the engine longitudinal direction. One end of the camshaft 210 is inserted into the cam sprocket 270. The cam sprocket 270 rotates with torque transmitted from the crankshaft of the engine. The camshaft 210 rotates with the cam sprocket 270. The camshaft 210 rotates relative to the cam sprocket 270 by hydraulic pressure, and can change the phase with respect to the cam sprocket 270. With such a structure, the rotational phase of the camshaft 210 relative to the crankshaft can be changed. A cam 211 is fixed to the camshaft 210. The cam 211 rotates integrally with the cam shaft 210. A pair of swing cams 260 connected by pipes are inserted through the camshaft 210. The swing cam 260 swings about the camshaft 210 as a rotation center and opens and closes the intake valve 51.

  The link arm 220 is supported through the cam 211.

  The valve lift control shaft 230 is disposed in parallel with the camshaft 210. A cam 231 is integrally formed on the valve lift control shaft 230. The valve lift control shaft 230 is controlled by an actuator 280 so as to rotate within a predetermined rotation angle range.

  The rocker arm 240 is supported through the cam 231 and is connected to the link arm 220.

  The link member 250 is connected to the rocker arm 240.

  The swing cam 260 is inserted through the cam shaft 210 and can swing about the cam shaft 210. The swing cam 260 is connected to the link member 250. The swing cam 260 moves up and down to push down the intake valve 51 via the tappet 53.

  Next, the operation of the variable valve mechanism 200 will be described with reference to FIG.

  FIGS. 6A-1 and 6A-2 are views showing a state when the lift amount of the intake valve 51 is maximized. FIG. 6A-1 shows a state where the intake valve 51 is closed and the swing direction of the swing cam 260 is reversed. That is, at this time, the cam nose 260b is at the highest position. FIG. 6 (A-2) shows a state where the intake valve 51 is in the open state and the swing direction of the swing cam 260 is reversed. That is, at this time, the cam nose 260b is at the lowest position.

  6 (B-1) and 6 (B-2) are views showing a state when the lift amount of the intake valve 51 is minimized. FIG. 6B-1 shows a state where the cam nose 260b is at the highest position and the swing direction of the swing cam 260 is reversed. FIG. 6B-2 shows a state where the cam nose 260b is at the lowest position and the swing direction of the swing cam 260 is reversed. In the present embodiment, the maximum lift amount of the intake valve 51 is zero. Therefore, in FIGS. 6B-1 and B-2, the intake valve 51 is always closed regardless of the operation of the swing cam 260.

  In order to increase the lift amount of the intake valve 51, as shown in FIGS. 6A-1 and 6A-2, the valve lift control shaft 230 is rotated to lower the position of the cam 231 and the shaft center P1 is pivoted. Set below the heart P2. As a result, the entire rocker arm 240 moves downward.

  When the camshaft 210 is rotationally driven in this state, the driving force is transmitted from the link arm 220 → the rocker arm 240 → the link member 250 → the swing cam 260.

  As shown in FIG. 6A-1, when the cam 211 is on the left side of the camshaft 210, the base circle portion 260a of the swing cam 260 is in contact with the tappet 53. At this time, the intake valve 51 is closed. To do.

  As shown in FIG. 6A-2, when the cam 211 is on the right side of the camshaft 210, the cam nose 260b of the swing cam 260 is in contact with the tappet 53. At this time, the intake valve 51 is opened.

  In order to reduce the lift amount of the intake valve 51, the valve lift control shaft 230 is rotated to raise the position of the cam 231 as shown in FIGS. Set to the upper right of the center P2. As a result, the entire rocker arm 240 moves upward.

  When the camshaft 210 is rotationally driven in this state, the driving force is transmitted from the link arm 220 → the rocker arm 240 → the link member 250 → the swing cam 260.

  As shown in FIG. 6B-1, when the cam 211 is on the left side of the camshaft 210, the base circle portion 260a of the swing cam 260 is in contact with the tappet 53. At this time, the intake valve 51 is closed. To do.

  As shown in FIG. 6B-2, even when the cam 211 is on the right side of the camshaft 210, the base circle portion 260a of the swing cam 260 is in contact with the tappet 53. At this time, the intake valve 51 Closes.

  As described above, when the valve lift control shaft 230 is rotated to raise the position of the cam 231 and the shaft center P1 is set to the upper right of the shaft center P2, the camshaft 210 rotates to swing the swing cam. Even if it moves, the intake valve 51 is always closed.

  FIG. 7 is a diagram showing the lift amount and opening / closing timing of the intake valve 51 by the variable valve mechanism 200. A solid line shows the lift amount and opening / closing timing of the intake valve 51 when the valve lift control shaft 230 is rotated. The broken line is a diagram showing the opening / closing timing of the intake valve 51 when the phase of the camshaft 210 with respect to the cam sprocket 270 is changed.

  According to the structure of the variable valve mechanism 200 described above, the lift amount and operating angle of the intake valve 51 can be continuously changed. Thus, by changing the angle of the valve lift control shaft 230 and the phase of the camshaft 210 with respect to the cam sprocket 270, the lift amount and the operating angle of the intake valve 51 can be changed continuously and freely.

  In this embodiment, the smaller the load, the smaller the intake valve operating angle, the valve closing timing (IVC) is advanced, the intake is stopped in the middle of the intake stroke, and the intake is expanded before and after bottom dead center.・ Compress. In this way, the engine is operated in a mirror cycle that changes the actually effective suction stroke, reduces the cylinder volume at the start of compression, and reduces pump loss (pump loss).

  However, in such an engine, when the actual compression ratio decreases, the in-cylinder temperature at the time of ignition may decrease, and the combustion speed may decrease.

  Therefore, in such an engine, as shown in FIG. 8B, in a low load operation region where the actual compression ratio becomes lower than a predetermined compression ratio by adjusting the closing timing (IVC) of the intake valve. The radical generation amount was increased so that the amount of the air-fuel mixture that increases the chemical activity increased as the load decreased.

  If the ignition pressure is high, the amount of radical generation can be controlled by increasing the corona discharge voltage within a range where ignition does not occur. However, when the ignition pressure becomes low, it becomes easier to make a transition to arc discharge. Therefore, in this embodiment, when the ignition pressure is low, the radical generation amount is controlled by lowering the corona discharge voltage for radical generation and increasing the number of corona discharges.

  According to the present embodiment, even in an engine that adjusts the intake air amount by controlling the advance / retard of the intake valve closing timing (IVC), radicals can be generated reliably, and the lean combustion operating range of the engine can be reduced. Stable combustion is possible even if it is enlarged. In particular, when the ignition pressure is low, the radical generation amount is controlled by lowering the corona discharge voltage for radical generation and increasing the number of corona discharges. Can now be generated.

(Third embodiment)
FIG. 9 is a diagram showing a third embodiment of the engine ignition control apparatus according to the present invention.

  The engine of the present embodiment includes two independent electrodes, a discharge electrode 11-1 for generating radicals and an electrode 11-2 for igniting the mixture.

  With such a structure, the discharge for radical generation and the discharge for mixture ignition can be performed simultaneously or at very short intervals. Therefore, radical distribution can be easily controlled. Moreover, since radicals can be generated while igniting the air-fuel mixture, combustion can be further promoted.

(Fourth embodiment)
FIG. 10 is a diagram showing a fourth embodiment of the engine ignition control apparatus according to the present invention.

  The air-fuel mixture ignition electrode 11-2 of the present embodiment is installed on the outer periphery of the combustion chamber.

  By doing in this way, radical distribution at the time of full load can be enlarged irrespective of gas flow.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  For example, in the second embodiment, the actual compression ratio is changed by adjusting the intake air amount by adjusting the intake valve closing timing, but the actual compression ratio is changed by mechanically adjusting the piston top dead center position. In the case of a variable compression ratio engine that changes the ratio, control may be performed so as to switch the discharge method for generating radicals with respect to the in-cylinder pressure at the ignition timing.

It is a block diagram which shows 1st Embodiment of the engine ignition control apparatus by this invention. It is explanatory drawing of the control method of radical amount and radical distribution. It is a control map of an engine ignition control device. It is a figure which shows the effect | action of this invention. It is a figure which shows the variable valve mechanism used for 2nd Embodiment of the engine ignition control apparatus by this invention. It is operation | movement explanatory drawing of a variable valve mechanism. It is a figure which shows the lift amount and opening / closing timing of the intake valve by a variable valve mechanism. It is a figure explaining the control method of the radical quantity of an engine which has a variable valve mechanism, and radical distribution. It is a figure which shows 3rd Embodiment of the engine ignition control apparatus by this invention. It is a figure which shows 4th Embodiment of the engine ignition control apparatus by this invention.

Explanation of symbols

10 Engine ignition control device 11 Discharge electrode (radical generation means)
11a Center electrode 11b Side electrode 11c Insulator 12 Short pulse high voltage generator 20 Engine 21 Combustion chamber 70 Controller (radical control means)
200 Variable valve mechanism

Claims (20)

An engine ignition control device comprising radical generating means capable of generating radicals in a combustion chamber, and igniting an air-fuel mixture after generating radicals in the combustion chamber during operation in a radical generation operation region,
During operation in the radical generation operation region, it has radical control means for adjusting radical generation by the radical generation means based on the engine operating state,
An engine ignition control device. The radical generation operation region is a lean combustion operation region,
The engine ignition control device according to claim 1. The radical control means increases the amount of radical generation as the engine rotation speed in the engine operating state decreases.
The engine ignition control device according to claim 1 or 2, characterized by the above. The radical control means increases the amount of radical generation as the engine load in the engine operating state is smaller.
The engine ignition control device according to any one of claims 1 to 3, wherein the engine ignition control device is provided. The radical control means increases the radical distribution as the engine rotation speed in the engine operating state is smaller.
The engine ignition control device according to any one of claims 1 to 4, wherein the engine ignition control device is provided. The radical control means increases the radical distribution as the engine load in the engine operating state is smaller.
The engine ignition control device according to any one of claims 1 to 5, wherein the engine ignition control device is provided. The radical generating means is a discharge electrode that generates a radical by generating corona discharge due to low-temperature plasma when a short pulse high voltage is applied,
The engine ignition control device according to any one of claims 1 to 6, wherein the engine ignition control device is provided. The discharge electrode is applied with a short pulse high voltage to generate a corona discharge by low-temperature plasma to generate radicals, and then generates an arc discharge by thermal plasma to ignite the mixture.
The engine ignition control device according to claim 7. The radical control means increases the radical distribution by shortening the discharge interval from corona discharge to arc discharge of the discharge electrode.
The engine ignition control device according to claim 8. A flow intensity control means capable of controlling the gas flow strength in the combustion chamber and increasing the radical distribution by weakening the gas flow strength;
The engine ignition control device according to claim 9. The flow strength control means reduces the distance from the discharge electrode of the radical by reducing the gas flow strength,
The engine ignition control device according to claim 10. The radical control means increases the amount of radical generation by increasing the corona discharge voltage applied to the discharge electrode.
The engine ignition control device according to any one of claims 7 to 11, wherein the engine ignition control device is any one of claims 7 to 11. The radical control means increases the amount of radical generation by increasing the number of times of applying a corona discharge voltage to the discharge electrode.
The engine ignition control device according to any one of claims 7 to 12, characterized in that: It further has a variable compression ratio mechanism that can change the actual compression ratio according to the engine load,
The radical control means increases the amount of radical generation as the engine load in the engine operating state is smaller.
The engine ignition control device according to any one of claims 1 to 13, wherein the engine ignition control device is any one of claims 1 to 13. The variable compression ratio mechanism is a mechanism capable of changing the actual compression ratio by controlling the intake air amount by adjusting the closing timing of the intake valve.
The engine ignition control device according to claim 14. The variable compression ratio mechanism is a mechanism that can change the actual compression ratio by mechanically adjusting the piston top dead center position.
The engine ignition control device according to claim 14. The radical control means increases the amount of radical generation by increasing the corona discharge voltage applied to the discharge electrode when the ignition pressure is higher than a predetermined pressure, and applies to the discharge electrode when the ignition pressure is lower than the predetermined pressure. Increase radical production by increasing the number of times the corona discharge voltage is applied,
The engine ignition control device according to any one of claims 14 to 16, characterized in that: An ignition means that is provided independently of the radical generation means and ignites the air-fuel mixture after the radicals are generated in the combustion chamber;
The engine ignition control device according to any one of claims 1 to 17, characterized in that: The ignition means is provided in the ceiling portion of the combustion chamber together with the radical generating means.
The engine ignition control device according to claim 18. The ignition means is provided on the outer peripheral portion of the combustion chamber,
The engine ignition control device according to claim 18.

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