JPH08100738A - Ignition device of direct injection type diesel engine - Google Patents

Abstract

PURPOSE: To stabilize property of an engine in mass-producing as well as to improve ignition precision. CONSTITUTION: A fuel injection nozzle insertion hole 8 is provided on a cylinder head 7 toward a combustion chamber 5 and an integrated fuel injection nozzle constituted of a porous fuel injection nozzle part 11 and an ignition electrode part 21 is inserted into the fuel injection nozzle insertion hole 8. One ignition hole 15a excessively used for ignition, penetrating at the angle θ intersecting approximately perpendicular to the cylinder axis L is provided on the tip of the fuel injection nozzle part 11, independent of a normal injection hole, and the tip of the ignition electrode part 21 is so set that the upper surface 31a of spray 31 injected from the injection hole 15a may approximately match the lower surface 24a of a spark clearance 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for a direct injection type diesel engine, and more specifically, it faces a combustion chamber with a porous fuel injection nozzle and an ignition means, and the ignition means causes an injection hole of the porous fuel injection nozzle. The present invention relates to an ignition device for a direct injection diesel engine, which is adapted to ignite a spray injected from a vehicle.

[0002]

2. Description of the Related Art A diesel engine is an engine in which only air is sent into a cylinder, and the air is compressed into a high-temperature, high-pressure state, and fuel is sent as atomized fuel to be self-ignited for combustion. In order to self-ignite the fuel, it is necessary to set the compression ratio to about 15 to 22, which is higher than that of the gasoline engine, and raise the fuel to the temperature at which it spontaneously ignites. Therefore, in a diesel engine, a fuel injection pump and a fuel injection nozzle that atomize the fuel and inject it into the cylinder are provided to facilitate ignition, and
We use fuel such as light oil that easily ignites itself.

However, when the load is low, the amount of fuel injected from the fuel injection nozzle is small, so that it is difficult to ignite, and there is a problem that the amount of hydrocarbons, smoke, blue and white smoke, unburned methanol, aldehyde, etc., increases. With respect to such a problem, by arranging an ignition means such as an ignition plug facing the combustion chamber together with the fuel injection nozzle and igniting the spray by the ignition plug, the fuel can be reliably ignited at a low load. Such a direct injection diesel engine has been proposed.

FIG. 6 is a longitudinal sectional view of a cylinder peripheral portion showing an example of such a direct injection diesel engine.
In this direct injection type diesel engine 101, a piston 103 is fitted in a cylinder 102 so as to be vertically movable.
A cavity 104 is recessed in the top surface of the piston 103, and a heart-shaped combustion chamber 105 is formed in the cavity 104.
Are formed. A cylinder head 107 is attached to the upper side of the cylinder block 106. The cylinder head 107 is provided with a fuel injection nozzle insertion hole 108 and an ignition plug insertion hole 109, and each insertion hole 1
The fuel injection nozzle 110 and the spark plug 1 are provided at 08 and 109.
11 is attached. At the time of this attachment, the spark gap of the spark plug 111 is set to the fuel injection nozzle 11
It is necessary to set the optimum position so that the spray is injected from 0 to the combustion chamber 105 neither too close nor too far.

[0005]

However, since both the fuel injection nozzle 110 and the ignition plug 111 are structured so as to be inserted into the respective insertion holes 108 and 109 and attached, the relative relationship between the fuel injection nozzle 110 and the ignition plug 111. It is very difficult to set the positional relationship with high accuracy.
For example, even in the case of the fuel injection nozzle 110 as an example, a tilt error due to the fact that the axis of the fuel injection nozzle insertion hole 108 and the axis of the fuel injection nozzle 110 that is actually attached do not match, the attachment of the fuel injection nozzle 110 in the front-back direction There is an error.

The inclination error and the mounting error in the front-back direction also occur when mounting the ignition plug 111 in the insertion hole 109. Further, considering the electrode arrangement error of the ignition plug 111 itself, the injection hole of the fuel injection nozzle 110, the ignition Plug 11
It is not easy to accurately set each position of the No. 1 spark gap in the combustion chamber 105. Therefore, FIG.
A conventional direct injection diesel engine 10 as shown in FIG.
With the configuration of 1, the setting of the distance between the injection hole and the spark gap, the setting of the direction of the spark gap relative to the injection hole, the setting of the distance between the spray injected from the injection hole and the spark gap, and the orientation of the outer electrode of the spark plug 111 are performed. It was difficult to set, and there was a problem that the engine characteristics were not stable due to the large difference between the engines during mass production. Spark plug 111 during spraying especially due to installation error
When the spark gap is set to be positioned, there is a problem that carbon of fuel adheres to the spark gap to cause ignition failure.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a direct injection diesel engine capable of easily improving ignition accuracy and stabilizing the characteristics of an engine during mass production. It is an object of the present invention to provide an ignition device.

[0008]

An ignition device for a direct injection type diesel engine according to claim 1 for achieving the above object is, for example, referring to FIG. In a direct injection diesel engine igniter in which a nozzle and an igniting means are faced to ignite the spray injected from the injection hole of the perforated fuel injection nozzle by the igniting means, the porous fuel injection nozzle portion 11 is ignited. It is characterized in that the ignition electrode portion 21 as means is integrally supported. Further, in the ignition device for the direct injection type diesel engine according to claim 2, the upper surface 31a of the spray 31 injected from the injection hole 15a of the fuel injection nozzle portion 11 is substantially coincident with the lower surface 24a of the spark gap 24 of the ignition electrode portion 21. It is characterized by doing.

[0009]

In the ignition device for a direct injection type diesel engine according to claim 1, since the ignition electrode portion 21 is integrally supported by the fuel injection nozzle portion 11 for feeding the fuel as the spray 31, one of them is previously set. It becomes possible to adjust the relative position between the injection hole 15a and the ignition gap 24 by the body fuel injection nozzle 10 alone. Therefore, the above-mentioned position setting, for example, the distance setting between the injection hole 15a and the spark gap 24, the injection hole 1
5a, the direction of the spark gap 24, the distance between the spray 31 and the spark gap 24, the outer electrode 22 of the ignition electrode portion 21.
Since it is possible to almost eliminate each error in the setting of the direction, the ignition accuracy of the ignition electrode portion 21 can be improved. In the case of the direct injection diesel engine ignition device according to claim 2, the injection hole 15 a of the fuel injection nozzle unit 11
The upper surface 31a of the spray 31 ejected from the ignition electrode part 2
By substantially matching the lower surface 24a of the spark gap 24 of No. 1, the distance between the spark gap 24 and the spray 31 can be reduced, and the spray can be reliably ignited.
It is possible to prevent the occurrence of ignition failure due to fuel shortage and carbon short circuit.

[0010]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. 1 to 3 are views showing a first embodiment of an ignition device for a direct injection diesel engine of the present invention.
Is an enlarged vertical cross-sectional view of a main part showing the positional relationship between the fuel injection nozzle and the ignition electrode, FIG. 2 is a vertical cross-sectional view of a direct injection diesel engine, and FIG. 3 is a layout view of injection holes when the fuel injection nozzle is viewed from the tip side. Is. In the direct injection diesel engine 1 according to this embodiment, as shown in FIG. 2, a piston 3 is fitted in a cylinder 2 so as to be vertically movable. A cavity 4 is recessed in the top surface of the piston 3, and a heart-shaped combustion chamber 5 is formed in the cavity 4. A cylinder head 7 is attached to the upper side of the cylinder block 6, and a head cover (not shown) is attached to the upper side of the cylinder head 7.

Further, the cylinder head 7 is provided with a fuel injection nozzle insertion hole 8 vertically toward the combustion chamber 5, and an integrated fuel injection nozzle 10 is inserted into the fuel injection nozzle insertion hole 8. The integrated fuel injection nozzle 10 is composed of a fuel injection nozzle portion 11 and an ignition electrode portion 21 as shown in FIG. The fuel injection nozzle unit 11 adopts an automatic hydraulic nozzle system, and the needle valve 1 is attached to the nozzle body 12.
3, the fuel pumped from the injection pump is supplied to the oil sump 14 provided at the tip of the nozzle body 12, the needle valve 13 is opened by hydraulic pressure, and the injection hole provided at the tip of the nozzle. 15 is configured to inject fuel. As shown in FIG. 3, five injection holes 15 are provided. The injection holes 15a are dedicated to ignition and penetrate through the cylinder axis L at an angle θ substantially orthogonal to the cylinder axis L. It has four injection holes 15b inclined by φ.

The ignition electrode portion 21 is composed of two electrodes, and most of the two electrodes are embedded in the nozzle body 12 in parallel with the needle valve 13. The tips of the two electrodes are exposed at the circumference of the nozzle body 12, the outer electrode 22 is bent in an inverted L shape, and a spark gap 24 is formed with the tip of the center electrode 23. Between the outer peripheral side electrode 22 and the center side electrode 23, and the nozzle body 1
The two are insulated from each other by an insulator 26. Also, the angle θ
The exposed lengths of the two electrodes 22 and 23 are set so that the upper surface 31a of the spray 31 ejected from the injection hole 15a penetrating through is substantially coincident with the lower surface 24a of the spark gap 24. A mounting port 33 is provided at the upper end of the integrated fuel injection nozzle 10 so as to communicate with a fuel passage 19 for supplying fuel to the oil sump 14 and to connect to an injection pump. Further, the fuel relief valve 34, the outer peripheral electrode 21,
Terminals 35 for applying a high voltage to the center side electrode 23 are provided respectively.

The operation of the direct injection diesel engine 1 having the above structure will be described. Air is sucked into the cylinder 2 in the intake stroke, and the piston 3 rises in the compression stroke to move the fuel into the sufficiently compressed air.
Fuel is injected in a spray form from the injection holes 15a and 15b. In this case, since the ignition electrode part 21 is integrally attached to the fuel injection nozzle part 11, the spark gap 24 of the ignition electrode part 21 and the injection hole 15a of the fuel injection nozzle part 21 are accurately positioned in advance. By adjusting, the spark gap 24 and the injection hole 15a can be obtained only by attaching the integrated fuel injection nozzle 10 to the fuel injection nozzle insertion hole 8.
It becomes possible to position the position of the extremely accurately. The proper distance between the upper surface 31a of the spray 31 and the spark gap 24 is 0.5 mm, and accurate positioning is required, but according to the present embodiment, the above position setting can be easily performed.

Further, the spray 3 injected from the injection hole 15a
The upper surface 31a of 1 is 0.5 m with the lower surface 24a of the spark gap 24.
Since it is set to have an interval of m, spray 3
Sparks can be emitted in a state very close to 1, and fuel can be reliably ignited. Further, the ignition electrode 2 is included in the spray 31.
When 2 and 23 are arranged, the fuel is directly applied to the spark gap 24 to cause a short circuit due to carbon, which causes ignition failure. However, by setting as described above, ignition failure can be prevented. Further, in the present embodiment, as shown in FIG. 3, by providing the four injection holes 15b for injecting a large amount of fuel, the fuel can be evenly injected into the combustion chamber 5 and the four injection holes 15b are provided. By comparison, by providing the injection hole 15a for ignition only on the base end side, it is possible to increase the certainty of ignition while maintaining the uniform distribution of fuel.

[0015]

[Embodiment 2] FIG. 4 is an enlarged vertical sectional view of an essential part showing a second embodiment of the present invention. This embodiment differs from the first embodiment in that the injection hole 15 is composed of only the injection hole 15b inclined by an angle φ with respect to the cylinder axis L, and one of the injection holes 1
5b only in that the ignition electrode portion 21 is provided. With the configuration of this embodiment, the injection hole 15 dedicated to ignition is used.
Instead of providing a, the exposed width of the ignition electrode portion 21 becomes long. Also in this embodiment, the spray 31
The angle can be made symmetrical with respect to the cylinder axis L, and there is an advantage that a uniform distribution of the spray 31 can be achieved in the symmetrical heart-shaped combustion chamber 5.

[0016]

[Embodiment 3] FIG. 5 is an enlarged longitudinal sectional view of an essential portion showing a third embodiment of the present invention. This embodiment is different from the second embodiment in that it has one injection hole 15a penetrating at an angle θ that is substantially orthogonal to the axis M of the integrated fuel injection nozzle 10 and that the angle is closer to the combustion chamber 5 side. The point where three injection holes 15b inclined by φ and the fuel injection nozzle insertion hole 8 provided in the cylinder head 7 are (θ-
Only points inclined by an angle α such that α) = (φ + α). According to this embodiment, the integrated fuel injection nozzle 1 is used when the injection hole for ignition cannot be provided.
Even when 0 cannot be arranged perpendicularly to the combustion chamber 5, the effect of the present invention can be achieved. In addition, according to this embodiment, the injection angle of the spray 31 can be made symmetrical with respect to the cylinder axis L while it can be configured with only four injection holes and the exposure width of the ignition electrode portion 21 is kept short. And a uniform spray 3 in the combustion chamber 5
The advantage is that a distribution of 1 can be achieved.

The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the present invention. Hereinafter, such an embodiment will be described. (1) In the first to third embodiments, the fuel injection nozzle unit 1
The description has been made assuming that the number of the injection holes 15 is 5 or 4, but the number of the injection holes provided corresponding to the size of the combustion chamber 5 and the like can be increased. (2) Further, the problem to be solved by the present invention has been described by taking the problem at the time of low load as an example. However, when the engine is started in a cold region, when the air is thin in a high place, and the like, a fuel that does not easily self-ignite is used. In the case of doing so, the ignition of the fuel also deteriorates. Therefore, it is possible to apply the ignition device of the present invention when a fuel that is difficult to self-ignite is used in a direct injection diesel engine, or in a direct injection diesel engine used in cold regions or high altitudes.

[0018]

As described above, according to the invention of claim 1,
The following unique effects can be achieved. (A) The direction and distance of the spark gap of the ignition electrode with respect to the injection hole of the fuel injection nozzle, and the direction of the outer electrode, by integrally supporting the ignition electrode on the fuel injection nozzle that sends fuel as spray Since each of the errors can be almost eliminated, the ignition accuracy of the ignition electrode can be improved. (B) Since the position of the spark gap of the ignition electrode with respect to the injection hole can be set accurately separately from the attachment to the engine, the number of manufacturing steps can be significantly reduced compared to the conventional setting at the time of attachment. The characteristics of mass-produced engines can be stabilized.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, (c) the upper surface of the spray injected from the injection hole of the fuel injection nozzle is substantially the lower surface of the spark gap of the ignition electrode. By making them coincide with each other, the distance of the spark gap can be shortened with respect to the spray, the fuel can be reliably ignited, and it is possible to prevent the fuel from being applied to the spark gap and short-circuiting with carbon to cause ignition failure. There is a unique effect.

[Brief description of drawings]

FIG. 1 is an enlarged longitudinal cross-sectional view of a main part showing a positional relationship between a fuel injection nozzle and an ignition electrode according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a first embodiment of the present invention.

FIG. 3 is a schematic layout diagram of injection holes of a fuel injection nozzle.

FIG. 4 is an enlarged vertical sectional view of an essential part showing a second embodiment of the present invention.

FIG. 5 is an enlarged vertical sectional view of an essential part showing a third embodiment of the present invention.

FIG. 6 is a vertical sectional view showing an example of a conventional fuel injection ignition type engine.

[Explanation of symbols]

11 ... Fuel injection nozzle portion, 15a ... Injection hole, 21 ... Ignition electrode portion, 31 ... Spray, 31a ... Spray upper surface, 24 ... Spark gap, 24a ... Spark gap lower surface.

Claims (2)

[Claims] 1. A direct injection diesel engine ignition device in which a porous fuel injection nozzle and an ignition means are faced to a combustion chamber, and a spray injected from an injection hole of the porous fuel injection nozzle is ignited by the ignition means. 2. An ignition device for a direct injection diesel engine, characterized in that a porous fuel injection nozzle (11) integrally supports an ignition electrode (21) as an ignition means. 2. The upper surface (31) of the spray (31) injected from the injection hole (15a) of the porous fuel injection nozzle (11).
Ignition device for a direct injection diesel engine, characterized in that a) substantially coincides with the lower surface (24a) of the spark gap (24) of the ignition electrode (21).