JPH0437253B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a diesel engine, and more particularly to a highly insulated diesel engine in which a combustion chamber is partitioned with ceramic.

[Prior Art] Adiabatic engines that have been developed in recent years include coating the combustion chamber with ceramic or the like to define the combustion chamber, or the cylinder liner, cylinder head, piston head, etc. that define the combustion chamber. The combustion chamber is constructed by a method such as manufacturing of ceramics, etc., and takes advantage of the high heat resistance and large heat capacity of ceramics, etc. to suppress heat dissipation around the combustion chamber, increase thermal efficiency, and improve engine output. It is.

[Problems to be Solved by the Invention] As mentioned above, studies have been made on adiabatic engines to suppress heat dissipation from the surroundings of the combustion chamber and maintain the temperature inside the combustion chamber at a high temperature. Problems like this have arisen.

In other words, it is important to maintain the surroundings of the combustion chamber at a high temperature by improving insulation, but for this reason, even when intake air is introduced, the temperature inside the combustion chamber remains high, and the intake air During the stroke, the air sucked into the combustion chamber receives heat from the high-temperature inner wall of the combustion chamber and expands within the combustion chamber, reducing the amount of intake air introduced, resulting in a decrease in intake efficiency and a significant reduction in engine output. The problem of doing so has arisen.

In order to deal with such problems, it is considered ideal to temporarily cool only the surface layer of the inner wall of the combustion chamber.

Here, the applicant has previously attempted to lower the temperature in the combustion chamber by using a fuel injection nozzle and injecting appropriate cooling water into the combustion chamber during or immediately after fuel injection. "Insulated Diesel Engine" (Utility Model Publication No. 163634/1983)
proposed. Although this proposal has a considerable cooling effect, when cooling water is injected from the fuel injection nozzle, the injection position is the same as the fuel arrival position, and the injection timing is also determined in relation to the nozzle operation. Restricted at the same time as or immediately after fuel injection.

However, when considering both the demand for maintaining the combustion chamber at a high temperature and the demand for improving the intake efficiency during the intake stroke, there is usually room for improvement in the injection position and timing of the cooling water in the above proposal. It is desired to devise a system that can increase suction efficiency without unnecessary heat loss by injecting cooling water at appropriate locations and at appropriate times.

It is also desirable to be able to reduce the amount of cooling water and promote exhaustion by appropriately supplying cooling water.

[Means for Solving the Problems] The present invention comprises partitioning the combustion chamber using ceramic, and injecting water into the cylinder head so as to face the inner wall surface of the combustion chamber where the intake air flowing in from the intake port collides with the inner wall surface of the combustion chamber. A nozzle is provided to inject cooling water onto the inner wall surface only at the end of the exhaust stroke.

[Function] With the above configuration, the water injection nozzle cools the inner wall surface of the combustion chamber, which is a portion that imparts a large amount of heat to the intake air, at the end of the exhaust stroke.

[Embodiment] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 2, a ceramic cylinder liner 2 is installed inside the cylinder formed in the cylinder body 1, and a cylinder head 3 provided at the top of the cylinder body 1 has a section above the cylinder. A closing ceramic head liner 4 is installed. On the other hand, the piston 5 that reciprocates within the cylinder is constructed by having a piston crown 5b made of ceramic bolted together with the upper part of the piston skirt 5a to which the connecting rod 6 is connected. The combustion chamber 7 is defined by the ceramic cylinder liner 2, head liner 4, and piston crown 5b, and is configured to have high thermal efficiency by suppressing heat dissipation from around the combustion chamber. Ring-shaped distance pieces 8 are interposed between the outer peripheral side of the head liner 4 and the cylinder head 3 at the upper and lower portions to form a heat insulating air layer 9 therebetween. Furthermore, head liner 4
A ring plate-shaped gasket 10 is interposed between the upper part of the cylinder head 3 and the cylinder head 3. These configurations also improve the heat insulation of the combustion chamber 7.

As shown in FIGS. 1 and 2, an intake port 11 and an exhaust port 12 are formed through the cylinder head 3 and head liner 4, and these intake and exhaust ports 13 and 14 are provided with an intake port 11 and an exhaust port 12. , an intake valve 15 and an exhaust valve are provided for opening and closing these at predetermined times. Further, 16 is a fuel injection nozzle.

The combustion chamber 7 configured in this way includes the combustion chamber 7
A water injection nozzle 17 is provided facing the inner wall 7a of the engine and injecting cooling water W thereto. This water injection nozzle 17 is connected to the cylinder head 3 to the head liner 4.
is attached and supported. In particular, this water injection nozzle 17 is installed so as to face the inner wall surface portion A of the combustion chamber 7 with which the intake air flow S flowing in from the intake port 13 collides. When the intake valve 15 is open, the intake air flow S flows into the combustion chamber 7 from the intake port 13 at high speed, flows into the combustion chamber 7 at high speed while contacting the inner wall surface portion A forming a continuous intake flow path from the intake port side, and then flows into the combustion chamber 7 from the intake port side at high speed. It flows downstream from wall A while being gradually decelerated. Here, the ratio of the amount of heat transferred from the inner wall 7a of the combustion chamber 7 to the intake air flow S is the inner wall surface portion A that this intake air flow S collides with.
It is considered to be large. Therefore, the cooling water W is injected onto this inner wall surface portion A to cool the surface layer portion thereof.

Further, in this embodiment, the water injection nozzle 17 is formed with multiple injection ports, and can inject cooling water in a range corresponding to the inner wall surface portion A, which is assumed to be a considerable range. Also, water injection nozzle 17
In addition to the above-mentioned inner wall surface portion A, the multiple injection ports are also applied to inner wall portions where a large amount of heat is transferred from the intake air S, specifically, the lower surface of the head liner 4 near the inner wall surface portion A, the upper surface of the piston crown 5b, etc. Cooling water can be injected from some parts.

Furthermore, the injection timing of the water injection nozzle 17 is set so that the cooling water W is injected only at the end of the exhaust stroke, specifically, when the intake valve 15 and the exhaust valve overlap. If the cooling water is configured to be injected at the end of the exhaust stroke in this way, the cooling water W will be exposed to the high temperature in the combustion chamber 7 and vaporized, and will simply cool the inner wall 7a of the combustion chamber 7, etc. Not only that, the volume expansion caused by vaporization can promote the exhaust of combustion gas from within the combustion chamber 7,
It is also possible to remove the heat of vaporization from the gas remaining in the combustion chamber to lower its temperature.

With the above configuration, it is possible to locally and intensively cool areas where a large amount of heat is transferred to the intake air, thereby increasing the intake efficiency without unnecessary heat loss, and improving the engine output. I can do it.

Furthermore, since the water injection nozzle 17 that can inject the cooling water W with considerable force is employed, the cooling water W can be accurately delivered to a desired position, and the reliability of the cooling effect can be ensured.

In other words, the minimum amount of cooling water is required, and the equipment for pumping the cooling water does not become excessively large.

Note that cooling water is supplied to the water injection nozzle 17 at a predetermined injection timing from a water pump (not shown) similar to the injection pump for the fuel injection nozzle.

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are achieved.

A water injection nozzle is installed facing the inner wall of the combustion chamber where the intake air collides with the cylinder head, and the cooling water is injected onto the inner wall only at the end of the exhaust stroke, resulting in combustion that provides a large amount of heat to the intake air. In addition to cooling the inner wall of the room and improving suction efficiency,
The amount of cooling water can be reduced, and exhaust gas in the combustion chamber can be promoted.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a preferred embodiment of the present invention;
FIG. 2 is a side view thereof. In the figure, 7 is a combustion chamber, A is its inner wall surface, 13 is an intake port, and 17 is a water injection nozzle.

Claims (1)

[Claims] 1 The combustion chamber is partitioned with ceramic, and
A water injection nozzle is provided in the cylinder head so as to face the inner wall surface of the combustion chamber where the intake air flowing in from the intake port collides with the cylinder head, and is configured to inject cooling water onto the inner wall surface only at the end of the exhaust stroke. A diesel engine characterized by: