JPH0421010Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection nozzle, particularly a fuel injection nozzle that is installed in a diesel engine and injects fuel into a combustion chamber.

[Prior Art] A fuel injection nozzle installed in a diesel engine turns high-pressure fuel sent from a fuel injection pump into a fine mist and injects it into the combustion chamber of the engine. Most of the injection nozzles were made of heat-resistant metal, such as the fuel injection nozzle described in JP-A-55-117068.

[Problems that the invention aims to solve] However, as mentioned above, fuel injection nozzles made of heat-resistant metal have poor insulation properties and the tip receives heat from the combustion chamber, resulting in seizure of the needle valve and damage to the nozzle hole. Problems such as clogging and excessive wear of the valve seat sometimes occurred.

Therefore, in order to improve the insulation of the fuel injection nozzle, especially the tip facing the engine's combustion chamber,
As in the fuel injection nozzle described in Japanese Patent No. 151316, attempts have been made to construct a fuel injection nozzle in which only the tip portion is made of ceramic material.

However, when only the tip of the nozzle is made of ceramic, the surface precision of the inner surface of the nozzle hole, which injects the fuel into a fine mist into the combustion chamber, is poor, fluid resistance increases, and penetration due to turbulence of the atomized fuel occurs. There was a risk of problems such as a decrease in engine power and a decrease in fuel flow rate, resulting in deterioration of engine combustion efficiency.

In addition, in a fuel injection nozzle that is made of ruby or sapphire around the nozzle hole, such as the fuel injection nozzle described in Utility Model Application Publication No. 11163 of 1932, high-precision injection is possible with ruby or sapphire. There are problems with drilling holes by machining, and there are economic problems with fitting the ruby or sapphire into the hole provided at the tip of the nozzle body and fixing it to withstand high pressure, so there is a possibility that it is not suitable for mass production. It was hot.

The present invention was devised in order to solve the problems of the conventional fuel injection nozzle, and the tip of the nozzle body having the nozzle hole is made of ceramic material to improve the heat insulation properties of the tip. This improves the durability of the fuel injection nozzle, and by providing a coating layer of glass-like material on the inner surface of the nozzle hole of the ceramic tip,
The surface accuracy of the inner surface of the nozzle hole is improved to reduce fluid resistance, prevent a decrease in penetration and a decrease in fuel flow rate due to turbulence of the sprayed fuel, improve the combustion efficiency of the engine, and further improve the combustion efficiency of the engine. The object of the present invention is to provide a fuel injection nozzle that is reliable, has improved workability, and is suitable for mass production by preventing peeling of the coating layer.

[Means for Solving the Problems] In order to achieve the above object, the fuel injection nozzle of the present invention has a tip portion of the nozzle body having a nozzle hole made of a ceramic material, and a glass-like material on the inner surface of the nozzle hole. A coating layer is provided.

[Function] The function of the fuel injection nozzle of the present invention having the above configuration is as follows.

That is, since the tip of the nozzle body having the injection hole is made of ceramic material, the insulation of the tip is improved, and seizure of the needle valve, clogging of the injection hole, and excessive wear of the valve seat are prevented. The durability of the fuel injection nozzle is improved.

In addition, the tip of the nozzle body having the nozzle hole is made of ceramic material, and a coating layer of a glass-like material is provided on the inner surface of the nozzle hole, so the inner surface of the nozzle hole is formed smoothly and its surface precision is improved. This reduces fluid resistance, prevents a decrease in penetration and a decrease in fuel flow rate due to turbulence in the sprayed fuel, and improves engine combustion efficiency.

Furthermore, by providing a coating layer of glass-like material on the inner surface of the nozzle hole of the ceramic tip,
The ceramic material, which is an inorganic compound, and the coating layer of the glassy material are strongly bound together by ionic bonds, and the mutual attraction between the crystals is particularly strong at high temperatures, which stabilizes the bond structure and prevents the coating layer of the glassy material from peeling off. and reliability is improved.

[Example] Hereinafter, an example of the fuel injection nozzle of the present invention will be described with reference to the drawings.

1 is a nozzle body made of heat-resistant metal in a fuel injection nozzle that is attached to a diesel engine and injects fuel into a combustion chamber, and its tip portion 2 is made of a heat-resistant ceramic material.
is provided. The tip portion 2 constitutes an attachment portion to the nozzle body 1, and is composed of a disk portion 14 supported by the nozzle nut 5, and a bag-shaped portion 11 protruding downward from the center of the lower surface of the disk portion 14. One or more nozzle holes 16 are provided in this bag-shaped portion.

A key groove 3 is formed on the side of the mating surface of the nozzle body 1 and the tip part 2, and a key 4 is fitted into this key groove 3 to align the two, so as to cover the outer periphery of these members. A bag-shaped nozzle nut 5 is fitted from below, this nozzle nut 5 is screwed onto a threaded portion 6 formed on the outer periphery of the nozzle body 1, and further this nozzle nut 5 is screwed onto a cylinder head of an engine (not shown). and fix the tip part 2 so that the tip of the tip part 2 faces into the fuel chamber.

Reference numeral 7 denotes a needle valve, which slides on the sliding part of the nozzle body 1, and injects when the valve body 9 contacts or separates from the valve seat part 8 formed at the tip of the nozzle body 1. It is configured as follows. The tip of the needle valve 7 is reduced to form a narrow diameter portion 10;
This narrow diameter portion 10 is inserted into a hole inside a bag-like portion 11 formed at the tip of the distal end portion 2 to reduce the bag volume as much as possible.

The inner surface of the hole of the bag-shaped part 11 and the narrow diameter part 10
A gap 12 is formed between the tip 2 and the tip 2.
The narrow diameter portion 10 of the needle valve 7 is configured not to come into contact with the needle valve 7.

The tip of the nozzle nut 5 is connected to the disk portion 1 of the tip portion 2.
A projecting portion 13 is formed to support the lower surface of the nozzle body 1, and supports the bottom and side surfaces of the disk portion 14 of the tip portion 2, thereby attaching the disk portion 14 of the tip portion 2 to the bottom surface of the nozzle body 1. It's pressing. Furthermore, the disk portion 14 of the tip portion 2 is attached to the overhanging portion 13 of the nozzle body 1.
It is desirable to provide a heat insulating sheet between the tip portion 2 and the nozzle body 1 to prevent heat conduction between the tip portion 2 and the nozzle body 1.

In addition, a metallized layer is formed on the contact surface 15 between the tip of the nozzle body 1 and the tip 2, so that the tip 2 and the nozzle body 1 are integrally joined and the heat of the tip 2 is transferred to the nozzle body 1 side. It is desirable that the temperature is transmitted to the tip portion 2 to cool the tip portion 2 and prevent the fuel inside the tip portion 2 from becoming high temperature.

One or more nozzle holes 16 are provided at the tip of the tip portion 2, and a coating layer 17 of a glass-like material, which is the same inorganic compound as the ceramic material, is provided on the inner surface of the nozzle hole 16. It is being

The coating layer 17 formed on the inner surface of the nozzle hole 16 increases the smoothness, and by performing this processing, the surface precision of the nozzle hole 16 becomes a mirror finish state.

The process of forming the coating layer 17 of the glassy material is usually carried out on the tip portion 2 made of ceramic material.
Although it is possible to perform the coating process simultaneously with the sintering of the tip part 2, the coating process may be separately performed after the tip part 2 is sintered, if necessary.

The thickness of this coating layer of the glass-like material may be such that it can be coated upon sintering of the tip portion 2, which is usually made of a ceramic material.

Since the fuel injection nozzle of the present invention is constructed as described above, the inner surface of the nozzle hole 16 is smoothed and its surface precision is improved, making it appear as if it had been mirror-finished. The fluid resistance during injection is reduced, the penetration of the fuel spray is increased, and furthermore, a reduction in the fuel flow rate is prevented, and the combustion efficiency in the combustion chamber is improved.

In addition, since the tip of the present invention is made of ceramic material, it has improved heat insulation and heat resistance, and prevents seizure of the needle valve, clogging of the nozzle hole, and excessive wear of the valve seat compared to conventional heat-resistant metals. Problems with the manufactured fuel injection nozzle are resolved.

Furthermore, by providing a coating layer 17 of a glassy material on the inner surface of the nozzle hole 16 of the ceramic tip 2, the ceramic material, which is an inorganic compound, and the coating layer 17 of a glassy material are strongly bound together by ionic bonds. In particular, the mutual attraction between the crystals at high temperatures is strong, the bonding structure is stable, the coating layer 17 of the glass-like material is prevented from peeling off, and a reliable fuel injection nozzle can be provided.

In addition, since the nozzle hole 16 can be formed at the same time as the tip part 2 is molded, it is not limited to a circular shape, but can also be T-shaped,
A non-circular nozzle hole such as an X-shape can be easily formed.

Further, in the embodiment described above, only the tip bracket 2 having the nozzle hole 16 of the nozzle body 1 is made of ceramic material, but the entire nozzle body 1 may be made of ceramic material.

[Effects of the invention] As described above, in the fuel injection nozzle of the invention, the tip of the nozzle body having the nozzle hole is made of a ceramic material, and a coating layer of a glass-like material is provided on the inner surface of the nozzle hole. Therefore, the following effects are obtained.

That is, since the tip portion of the nozzle body having the nozzle hole is made of ceramic material, the heat insulation properties of the tip portion are improved, and seizure of the needle valve, clogging of the nozzle hole, and excessive wear of the valve seat are prevented. This has the effect of improving the durability of the fuel injection nozzle.

In addition, the tip of the nozzle body having the nozzle hole is made of ceramic material, and a coating layer of a glass-like material is provided on the inner surface of the nozzle hole, so the inner surface of the nozzle hole is formed smoothly and its surface precision is improved. This reduces fluid resistance, prevents a decrease in penetration and a decrease in fuel flow rate due to turbulence in the sprayed fuel, and has the effect of improving the fuel efficiency of the engine.

Furthermore, by providing a coating layer of glass-like material on the inner surface of the nozzle hole of the ceramic tip,
The ceramic material, which is an inorganic compound, and the coating layer of the glassy material are strongly bound together by ionic bonds, and the mutual attraction between the crystals is particularly strong at high temperatures, which stabilizes the bond structure and prevents the coating layer of the glassy material from peeling off. This has the effect of providing a reliable fuel injection nozzle.

In addition, the tip of the nozzle body with the nozzle hole is made of ceramic material, and the inner surface of the nozzle hole is coated with a glass-like material. Compared to forming by machining, it is cheaper and
This has the effect of providing a fuel injection nozzle that is easy to process and suitable for mass production.

[Brief explanation of the drawing]

The figure is an enlarged sectional view showing the main parts of a fuel injection nozzle according to an embodiment of the present invention. 1...Nozzle body, 2...Tip, 3...Keyway, 4...Key, 5...Nozzle nut, 6...Threaded part, 7...Needle valve, 8...Valve seat part, 9... valve body,
DESCRIPTION OF SYMBOLS 10... Thin diameter part, 11... Bag-shaped part, 13... Overhanging part, 14... Disc part, 16... Nozzle hole, 17...
...Coating layer of glassy material.

Claims (1)

[Scope of utility model registration request] A fuel injection nozzle comprising a nozzle body whose tip end having a nozzle hole is made of ceramic material, and a coating layer of a glass-like material is provided on the inner surface of the nozzle hole.