JPS6237939Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a starting heating device for a direct injection internal combustion engine.

[Conventional technology and its problems]

Currently, low-quality fuel is forced to be used, and the air in the intake pipe or the air in the combustion chamber is preheated in order to make the ignition conditions for the fuel more favorable during startup. Preheating in the intake pipe is performed by several hundred to
Providing a 2.3KW ribbon heater type intake air heating device is one example, but in such a case, a starter motor is used, so the ribbon heater type intake air heating device and the starter motor are powered by one power source. Therefore, if the starting motor and the intake air heating device are used simultaneously during starting, a large current will flow, making it difficult to use the ribbon heater. Therefore, such a heating device can be used for 20 to 30
After preheating for seconds, the starter motor is switched to start the engine. Therefore, after startup, the heating device does not heat up, and a large amount of irritating blue-white smoke is emitted during the period until warm-up, which is undesirable.

In addition, the main method for preheating the air in the combustion chamber is to screw a glow plug into the auxiliary combustion chamber and heat the coil by passing an electric current through it several minutes before starting the engine, thereby preheating the air in the combustion chamber. In such a case, if a glow plug is used in the direct injection combustion type, the risk of thermal stress in the fuel injection valve mounting hole and intake/exhaust valve hole in the cylinder head will be further exacerbated, and measures against heat load must be taken excessively.

[Means for solving problems]

The present invention avoids the above-mentioned problems of the conventional technology and provides a direct injection engine with a glow plug for starting aid, thereby providing a high-output engine that has good starting performance and does not disturb the intake swirl with the glow plug at high speeds and high loads. This is what I am trying to do.

〔Example〕

This will be explained in detail with reference to embodiments shown in the accompanying drawings. FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, and FIG. 2 is a view taken along arrows A to A in FIG. 1.

Intake hole 2 and exhaust hole 3 open toward cylinder 1
are bored in the cylinder head 4. A piston 5 is fitted into the cylinder 1 so as to move up and down, a toroidal combustion chamber 6 is provided in the crown of the piston 5, and a hole nozzle type fuel injection valve 7 is provided in the combustion chamber 6. ing. At the lower end surface of the cylinder head 4, the intake hole 2 and the fuel injection valve 7
A recess 8 is bored at a location sandwiched between the two, and the glow plug 10 is screwed into the recess 8 so that its tip faces the recess 8 and crosses directly below the intake port 9. In particular, the tip of the glow plug 10 is
When the engine is started, the fuel from the fuel injection valve 7 that collides with and extends outward from the outer peripheral wall 12 of the combustion chamber 6 comes into direct contact (see FIG. 3A). Moreover, its position is slightly downstream of the swirl from the spray direction of the injected fuel.

Therefore, the glow plug 10 has a slight inclination L=15° to 30° with respect to the lower end surface of the cylinder head 4.
It is screwed into the cylinder head 4 at . Since that part is sandwiched between the intake hole 2, which is constantly cooled by intake air, and the insertion hole 11 of the fuel injection valve 7, it is a part of the cylinder head 4 where thermal stress is small. There is no risk of cracks occurring.

Since this embodiment has the above-described configuration, when the engine speed is low, such as during startup, and the intake swirl that promotes mixing of the injected fuel and air to achieve good combustion is weak, As shown in FIGS. 2 and 3A, the fuel F injected from the nozzle 7a of the fuel injection valve 7 collides with the outer peripheral wall 12 of the toroidal combustion chamber 6, and the oil droplets floating indirectly in the spray Instead, the sprayed fuel collided with the toroidal recess of the piston 5 spreads along the outer peripheral wall 12, and the scattered fuel itself clings to the glow plug 10 as the compressed airflow flows into the recess 5 at the top dead center of the piston. In this way, a large amount comes into contact, resulting in reliable ignition.
To maintain good combustion after starting the engine. On the other hand, at high speeds and high loads, the intake swirl becomes strong, and as shown in FIG.
is caused to flow downstream through the outer peripheral wall 12 (as indicated by the arrow in FIG. 3B), and is circulated without flowing into the recess 8 described above, and the engine performance is not deteriorated without causing any swirl disturbance caused by the glow plug 10 or the like. Does not occur.

In summary, the present invention employs the structure described in the claims for utility model registration, and thus has the following effects.

[Operation and effect of the invention] When the engine speed is low and the intake swirl is weak, such as when starting the engine, the scattered fuel is injected from the fuel injection valve 7, collides with the outer peripheral wall of the combustion chamber, and spreads along the outer peripheral wall. As the compressed airflow flows into the recess 8, a large amount of compressed air comes into contact with the glow plug 10, which is tilted at an angle of approximately 15° to 30°, so as to ensure reliable ignition.

When the intake swirl at high speed and high load is strong, the scattered fuel that collides with the outer peripheral wall of the combustion chamber circulates along the swirl, and becomes irrelevant to the presence of the glow plug 10 facing the recess 8. Does not cause swirl disturbance and does not cause deterioration of combustion performance.

Because the glow plug hole is located between the intake hole, which is constantly cooled by intake air, and the fuel injection valve insertion hole, and directly below the intake port, thermal stress generated in the cylinder head can be avoided, and special thermal loads can be avoided. The cost of countermeasures can be reduced without having to take any countermeasures. If heat load countermeasures are taken (for example, applying a mirror finish to the tip of the glow plug hole and fuel injection valve insertion hole), cooling of the fuel injection valve will be inhibited, and the temperature increase will reduce the durability of the fuel injection valve. However, according to the present invention, a special Since no heat load measures are required, this problem does not occur and it can withstand the use of low-quality fuel.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a view along arrows A to A in FIG. 1, and FIG. 3 is a state diagram showing the relationship between the sprayed fuel and the glow plug. 2...Intake hole, 3...Exhaust hole, 4...Cylinder head, 5...Piston, 6...Combustion chamber, 7...
Fuel injection valve, 9...Intake port, 10...Glow plug, 11...Insertion hole.

Claims (1)

[Scope of claim for utility model registration] Combustion chamber 1 recessed in the crown of the piston
3, and in the cylinder head of a two-valve direct injection diesel engine with one intake valve and one exhaust valve, directly below the intake port 9 between the intake hole 2 and the insertion hole 11 of the fuel injection valve 7, And cylinder head 4
A glow plug 10 is provided with its tip facing into a recess 8 formed in the lower end surface of the cylinder head 4, and the glow plug 10 is inclined at an angle of about 15° to 30° with respect to the lower end surface of the cylinder head 4. In addition, the tip of the glow plug 10 is characterized in that the fuel from the fuel injector 7 collides with the outer circumferential wall 12 of the combustion chamber at the time of startup, and comes into direct contact with the fuel that spreads along the outer circumferential wall 12. A heating device for starting a direct injection internal combustion engine.