JP2824697B2 - Fuel ignition device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel ignition device that injects and collides fuel with a collision portion provided on a head surface of a piston to ignite the diffused fuel.

(Prior Art) A conventional engine, particularly a diesel engine, has a direct injection engine that directly injects fuel into a combustion chamber and a sub-chamber that injects fuel into the sub-fuel chamber due to differences in fuel injection method. It is roughly divided into an expression engine.

Compared with the sub-chamber engine, the direct injection engine has advantages such as a low fuel consumption rate, a low compression ratio, and excellent startability. Therefore, various forms of direct injection engines have been proposed.

By the way, in a conventional direct injection engine, fuel is injected from a multi-injection nozzle, and a fuel-air mixture is generated by the fuel and swirl injected in the multi-direction. However, intake resistance is reduced due to generation of the swirl. There is a problem that the intake rate increases and the intake rate decreases. Also, since the tip of the multi-hole nozzle, that is, the portion where the injection hole is provided, protrudes into the combustion chamber, the temperature becomes high and the fuel injection amount decreases due to the boiling of the fuel remaining in the sack portion, and the swirl is reduced. Since a large amount of fuel is injected into the center, there is a problem that the fuel in the latter half of the injection causes incomplete combustion and carbonizes.

Therefore, the fuel injected from the single injection hole nozzle collides with a collision portion provided inside the hole opening in the piston head portion,
The collision diffusion which solves the problems of the conventional direct injection engine by intersecting the fuel colliding and diffusing with the collision portion and the squish flow flowing into the hole to generate an air-fuel mixture. The engine is “Internal combustion engine Vol.27 No.345 19
88.7 P35 to P44 "and JP-A-63-176619.

(Problems to be Solved by the Invention) In such a conventional collision diffusion engine, when the load of the engine is low, the temperature in the combustion chamber is relatively constant, so that the fuel adheres to the collision portion, and There is a problem that the collision diffusion is hindered, and the fuel adhering to the collision portion is carbonized, which further deteriorates the collision diffusion of the subsequent fuel.

By the way, it is known that when the temperature of the surface of the collision portion is heated to about 700 ° C. or more, the fuel attached to the surface is vaporized and the amount of the attached fuel is reduced.

The present invention has been made in view of the above points, and aims to provide a fuel ignition device that ignites fuel that has collided with the surface of a collision portion even near a low load and heats the collision portion near the collision portion. Things.

(Means for Solving the Problems) According to the present invention, in the fuel ignition device for injecting and colliding fuel with a collision portion provided inside a hole opened in a head surface of a piston to ignite the diffused fuel, An injection nozzle for injecting and colliding fuel with a portion, a notch provided in an upper collision portion, and igniting fuel injected from the fuel injection nozzle at least near the top dead center of the piston, and loosely fitting with the notch. And a collision portion heating plug for transmitting heat to the collision portion and heating the collision portion, thereby providing a fuel ignition device.

(Function) In the fuel ignition device of the present invention, a part of the fuel immediately after the collision is ignited, the thermal energy of the flame generated by the ignition is transmitted to the collision portion, the collision portion is heated, and the surface of the collision portion is heated. Prevents fuel from sticking to the surface.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial sectional view showing a configuration of an engine according to the present invention.

Reference numeral 1 denotes a piston made of an aluminum alloy, which is reciprocally held in a cylinder 11. The upper end of the piston 1 in the figure is provided with a cavity 12 which is a hole opened in the upper end surface of the piston.

Inside the cavity 12, a collision portion 2 made of a sintered body of silicon nitride is provided.

Reference numeral 3 denotes a cylinder head connected to an upper portion of the cylinder 11, and a fuel injection nozzle 31 is provided at the cylinder head at a position where fuel is injected and collided with the collision portion 2. The fuel injection nozzle 31 is connected to a fuel pump 32 and injects fuel supplied from the fuel pump 32 to the collision section 2. The fuel pump 32 can freely change the fuel supply timing to the fuel injection nozzle 32 according to a control signal from the controller 5 described later.

An intake valve 33 opens and closes an intake port of the engine. Although not shown, the engine is provided with an exhaust valve for opening and closing an exhaust port of the engine.

Reference numeral 4 denotes a heating plug, which is supplied with electric power from a controller 5 described later and can freely change the temperature of the plug tip portion 41.

Reference numeral 5 denotes a controller, which is an input / output interface that controls input and output of signals to and from the outside, a ROM that stores programs and various data in advance, a CPU that performs calculations based on programs stored in the ROM, calculation results and input and output. The controller 5 includes a RAM for temporarily storing signal data, a control memory for controlling the flow of signals inside the controller 5, and the like.

The controller 5 is connected to a rotation sensor 51 that detects the rotation speed and rotation phase of the engine, and a load sensor 52 that detects the load state of the engine from the amount of depression of an accelerator pedal (not shown). Speed sensor 51
And a detection signal from the load sensor 52. Further, as described above, the controller 5 outputs a control signal to the fuel pump 32 and supplies power to the heating plug 4.

The power supply to the heating plug 4 is performed by a constant voltage pulse, and the supply amount of the power is controlled by increasing / decreasing a pulse interval, that is, duty control. During the rest period of the pulse, a constant current is supplied to the heating plug 4 and the resistance value of the heating plug 4 is measured.
Measure the internal temperature.

Next, the positional relationship between the collision section 2 and the heating plug 4 will be described.

FIG. 2 is a partially enlarged perspective view of the collision portion at the top dead center position of the piston.

A disc-shaped collision surface 21 is formed on the upper portion of the collision portion 2, and at least a surface of the collision surface 21 that contacts the fuel, that is, an upper end surface is covered with silicon carbide formed by a CVD method. The ceramic covering the collision surface 21 is not limited to silicon carbide, but may be silicon nitride, which is the same as the ceramic forming the collision portion 2. Further, the deposition direction is not limited to the CVD method, but may be a PVD method or a plasma spraying method. However, it is necessary to prevent the metal oxide used as a sintering aid from being mixed.

The collision surface 21 is provided with a notch 22, and the collision portion 1 and the heating plug 4 are loosely fitted to the plug tip 41 at the position near the top dead center of the piston 1. It is in. Therefore, for a predetermined phase period centered on top dead center, the collision surface
21 and the plug tip 41 will be close to each other.

Next, the operation of the engine having the above configuration will be described.

FIG. 3 is a sectional view taken along the line AA during fuel injection,
FIG. 4 is an enlarged view of the cavity 12 during fuel injection.

In FIGS. 3 and 4, the dot group a is the tip of the plug.
41 shows the flame of the fuel ignited by 41, and a plurality of thin lines of b indicate the fuel injected from the fuel injection nozzle 31 and the collision surface 21.
The arrow of c indicates the squish flow flowing into the cavity 12.

When the engine load state detected by the load sensor 52 is equal to or less than a predetermined load, that is, when the engine is in a low load state, the controller 5 supplies pulse power to the heating plug 4 to heat the plug tip 41 and , Rotation sensor
Based on the rotation speed signal from 51, the fuel pump 32 is instructed to perform fuel injection at a predetermined timing.

The fuel discharged from the fuel pump 32 is supplied to the fuel injection nozzle 31.
And collides with the collision surface 21. The colliding fuel is diffused along the collision surface 21 in all circumferential directions. Part of the diffused fuel comes into contact with the plug tip 41 in the heated state and is loaded. The flame due to the ignition is formed around the notch 22 as shown in a, and heats the collision surface 21. Accordingly, the temperature of the collision surface 21 increases, and the amount of fuel adhering to the collision surface 21 decreases.

Then, as the engine load increases and the temperature inside the cavity 12 detected by the heating plug 4 rises, the power supplied to the heating plug 4 decreases.

Further, the fuel that has not contacted the plug tip portion 41 and thus has not been ignited is mixed with the squish flow c to form an air-fuel mixture, and then ignited by compression ignition or flame propagation to perform normal combustion.

In the above, the embodiments of the present invention have been described in detail. However, various different embodiments can be easily configured without departing from the spirit of the present invention. Therefore, the present invention is not limited to those described in the claims. , Is not limited to a particular embodiment.

(Effects of the Invention) As described above, according to the present invention, a part of the fuel immediately after colliding with the collision part is ignited, and the thermal energy of the flame generated by the ignition is transmitted to the collision part, and the collision is performed. Heating the part prevents the fuel from sticking to the surface of the collision part, so that even when the load is low, the fuel that collides with the surface of the collision part does not adhere and remain, so that no carbide is deposited on the surface of the collision part. It is possible to provide a fuel ignition device capable of reliably performing collision diffusion of fuel.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing the structure of an engine according to the present invention, FIG. 2 is a partially enlarged perspective view of a collision portion at a top dead center position of a piston, and FIG.
FIG. 4 is an enlarged view of the cavity 12 at the time of fuel injection. DESCRIPTION OF SYMBOLS 1 ... Piston, 2 ... Collision part, 3 ... Cylinder head, 4 ... Heating plug, 5 ... Controller, 12 ... Cavity, 21 ... Collision surface, 31 ... Fuel injection nozzle, a ...
... Flame, b ... Flow of injected fuel, c ... Squish flow.

Claims (2)

(57) [Claims] 1. A fuel ignition device for injecting and colliding fuel with a collision portion provided inside a hole formed in a head surface of a piston and igniting the diffused fuel, comprising: an injection nozzle for injecting and colliding fuel with the collision portion; A notch provided in the collision portion, and igniting fuel injected from a fuel injection nozzle at least near the top dead center of the piston, and loosely fitting with the notch to transfer heat to the collision portion. And a collision part heating plug for heating the fuel ignition device. 2. The fuel ignition device according to claim 1, wherein the collision portion heating plug operates when the engine is under a low load.