JP4123243B2 - Multi-point ignition engine - Google Patents

Description

  The present invention relates to a multipoint ignition engine.

In the multipoint ignition engine described in Patent Document 1, spark plugs are arranged in accordance with swirl strength, mixture ratio distribution, and residual gas distribution.
JP-A-4-183925

  However, even if the spark plug is arranged in this way, there is room for reducing emissions of hydrocarbon HC and the like in the exhaust gas. In particular, there is much room for improvement in engines that generate squish.

  Accordingly, the inventors of the present invention have paid attention to the position of the leg portion of the ground electrode of the peripheral plug through intensive research and found that by regulating the position, combustion can be stabilized and an emission reduction effect can be obtained.

  The present invention has been made paying attention to such conventional problems, and in particular, in a multi-point ignition engine that generates squish, to stabilize combustion and reduce emissions of hydrocarbon HC and the like in exhaust gas. It is an object.

  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 formed by a cylinder head (12), a piston (14), an inner wall surface (12b) of the cylinder head and a crown surface (14a) of the piston, and the piston (14) is raised near the top dead center. A squish generator (21) that generates a forward squish when the piston (14) descends near top dead center, and a center plug disposed substantially at the center of the inner wall surface of the cylinder head. (31) and an inner wall surface of the cylinder head which is disposed closer to the cylinder than the center plug (31), and a leg portion (32c) of a ground electrode (32b) is squished with respect to the center electrode (32a). generator (21) and located on the same side, reverse squish it is middle of the piston is produced by flowing into the squish generating unit (21) when lowered in the vicinity of the top dead center Electrodes (32a) - and having a peripheral plug for igniting at the timing of flowing between the ground electrode (32b) (32).

  According to the present invention, the peripheral plug is positioned so that the leg portion of the ground electrode is on the same side as the squish generating portion with respect to the center electrode, and at the timing when the squish flows between the center electrode and the ground electrode, The plug was ignited. Since it did in this way, if it ignites at the timing which a reverse squish flows, for example, the gas flow by a reverse squish can reach | attain between a center electrode and a ground electrode, without being inhibited by the ground electrode leg part. As a result, a strong gas flow can be ignited, so that the diffusion rate of the subsequent flames can be increased, stable combustion can be performed, fuel consumption can be improved, and emissions can be reduced. If ignition is performed at the timing when the forward squish flows, the flame ignited by the peripheral plug is sent to the center of the combustion chamber without being obstructed by the ground electrode legs. Since the diffusion direction of the flame and the gas flow direction by the forward squish coincide, the diffusion of the flame can be promoted.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a view showing a first embodiment of a peripheral plug arrangement structure of a multipoint ignition engine according to the present invention, FIG. 1 (A) is a side view, and FIG. 1 (B) is a cylinder head viewed from the piston side. FIG.

  In the multipoint ignition engine 10, a combustion chamber 13 is formed by a cylinder block 11 and a cylinder head 12. This combustion chamber 13 is a pent roof type combustion chamber, and as shown in FIG. 1B, an intake valve 15 is disposed on one side of the pent roof ridge 12a, and an exhaust valve 16 is disposed on the other side. A central plug 31 and a peripheral plug 32 are arranged along the pent roof ridge line 12a.

  The piston 14 is formed with an inclined crown surface 14a that is convex toward the center of the combustion chamber at the peripheral portion of the crown surface located below the pent roof ridgeline 12a. A recess 14 b is formed near the center of the piston 14.

  On the inner wall surface of the cylinder head 12, a cylinder head inclined surface 12 b facing the inclined crown surface 14 a is formed.

  When the piston 14 rises to near the top dead center and the inclined crown surface 14a approaches the cylinder head inclined surface 12b, the air compressed by the inclined crown surface 14a and the cylinder head inclined surface 12b flows out toward the center of the combustion chamber. Do (order squish). When the piston 14 descends from the top dead center and the inclined crown surface 14a is separated from the cylinder head inclined surface 12b, air flows into the space formed by the inclined crown surface 14a and the cylinder head inclined surface 12b (reverse squish). . In FIG. 1, the reverse squish is indicated by an arrow A. Thus, the inclined crown surface 14 a and the cylinder head inclined surface 12 b are the squish generating unit 21.

  The center plug 31 is attached to the approximate center of the cylinder head 12. The center plug 31 ignites before compression top dead center. The peripheral plug 32 is attached to a position where the squish generated by the squish generator 21 can flow between the center electrode 32a and the ground electrode 32b. In the present embodiment, the peripheral plug 32 is ignited when a reverse squish flows between the center electrode 32a and the ground electrode 32b. Therefore, the peripheral plug 32 has ignition energy stronger than that of the central plug 31 so that it can be reliably ignited without blowing off against the gas flow. Specifically, it may be determined by a matching experiment. The peripheral plug 32 is positioned so that the leg portion 32c of the ground electrode 32b is on the same side as the squish generator 21 with respect to the center electrode 32a (the side that is substantially closer to the squish generator 21 with respect to the center electrode 32a). Yes. This positioning can be realized by adjusting the cutting start positions of the female screw formed on the cylinder head 12 and the male screw formed on the peripheral plug 32. Further, an alignment mark corresponding to the position of the ground electrode leg 32c may be attached to the housing of the peripheral plug 32, and positioning may be performed using the alignment mark as a mark.

  FIG. 2 is a diagram for explaining a control system for ignition timing of peripheral plugs.

  The peripheral plug 32 ignition timing control system 50 includes a crank angle sensor 51, a controller 52, and a peripheral plug 32.

  The controller 52 controls the ignition timing of the peripheral plug 32 based on the crank angle detected by the crank angle sensor 51. The controller 52 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 52 may be composed of a plurality of microcomputers.

  In this embodiment, the controller 52 ignites the peripheral plug 32 at a timing after the compression top dead center and when the reverse squish flows between the center electrode 32a and the ground electrode 32b. More preferably, ignition is performed before the flame of the center plug 31 arrives.

  It should be noted that the time after the compression top dead center and when the reverse squish is generated and the time before the center plug 31 reaches the flame are mapped by preliminary experiments, and the controller 52 determines the peripheral plug 32 based on the map. Controls the ignition timing.

  According to the present embodiment, the peripheral plug 32 is positioned so that the leg 32c of the ground electrode 32b is on the same side as the squish generator 21 with respect to the center electrode 32a, and the squish is generated between the center electrode 32a and the ground electrode 32b. The peripheral plug 32 is ignited at the timing when the reverse squish generated in the section 21 flows.

  Since it did in this way, the gas flow by reverse squish can reach | attain between the center electrode 32a and the ground electrode 32b, without being inhibited by the ground electrode leg part 32c. As a result, a strong gas flow can be ignited, so that the diffusion rate of the subsequent flames can be increased, stable combustion can be performed, fuel consumption can be improved, and emissions can be reduced.

  In addition, the squish generating unit 21 is formed below the pent roof ridge line 12a, and the peripheral plug 32 is disposed along the pent roof ridge line 12a. Therefore, when the squish generation unit is provided at the position where the squish generation unit is rotated 90 degrees with respect to the present embodiment (that is, the side of the two intake valves 15 or the side of the two exhaust valves 16) and the peripheral plug 32 is disposed. Because the roof is at a higher position compared to, it is easy to grow a flame.

(Second Embodiment)
FIG. 3 is a view showing a second embodiment of the peripheral plug arrangement structure of the multipoint ignition engine 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.

  In the first embodiment described above, the peripheral plug 32 is ignited at the timing when the reverse squish flows between the center electrode 32a and the ground electrode 32b after the compression top dead center, but in this embodiment, The peripheral plug 32 is ignited at the timing when the forward squish flows before the compression top dead center.

  As a result, the flame ignited by the peripheral plug 32 is sent to the center of the combustion chamber without being obstructed by the ground electrode leg 32c, and diffuses and propagates. As a result, the flame diffusion direction and the gas flow direction by the forward squish coincide with each other, so that the flame diffusion can be promoted, the flame diffusion speed can be increased, and stable combustion can be performed. As a result, fuel efficiency is improved and emissions of hydrocarbon HC and the like in the exhaust gas can be reduced.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea, and it is obvious that these are equivalent to the present invention.

  For example, the peripheral plug 32 may be ignited at a timing when a forward squish flows between the center electrode 32a and the ground electrode 32b, and may be ignited a plurality of times at a timing when a reverse squish flows.

It is a figure which shows 1st Embodiment of the periphery plug arrangement | positioning structure of the multipoint ignition engine by this invention. It is a figure explaining the control system of the ignition timing of a peripheral plug. It is a figure which shows 2nd Embodiment of the surrounding plug arrangement | positioning structure of the multipoint ignition engine by this invention.

Explanation of symbols

10 Multi-point ignition engine 10
11 Cylinder block 12 Cylinder head 12b Cylinder head inclined surface (cylinder head inner wall surface)
13 Pent roof type combustion chamber 14 Piston 14a Inclined crown surface (piston crown surface)
21 Squish Generator 31 Center Plug 32 Peripheral Plug 32a Center Electrode 32b Ground Electrode 32c Ground Electrode Leg

Claims (2)

A cylinder head;
A piston,
A squish formed by the inner wall surface of the cylinder head and the crown surface of the piston, which generates a forward squish when the piston rises near top dead center and generates a reverse squish when the piston descends near top dead center A generator,
A center plug disposed substantially at the center of the inner wall surface of the cylinder head;
It is the inner wall surface of the cylinder head and is disposed closer to the cylinder side than the center plug, the leg portion of the ground electrode is located on the same side as the squish generating portion with respect to the center electrode, and the piston is near top dead center A peripheral plug that ignites at the timing when the reverse squish generated by flowing into the squish generating unit flows down between the center electrode and the ground electrode when descending ;
Having a multi-point ignition engine. The peripheral plug is ignited at a timing when a forward squish generated by flowing out from the squish generating portion when the piston ascends near top dead center flows between the center electrode and the ground electrode.
The multi-point ignition engine according to claim 1.