JPS61218766A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To improve sealability so better as well as to reduce the cost of production, by interposing a valve body between a main fuel needle and a sub-fuel needle, while sealing it with seal oil to be fed out of a seal oil feeding port. CONSTITUTION:There is provided with a sub-fuel needle 6 which slides upward by dint of pressure in sub-fuel and opens a sub-fuel injection passage 12. Also there is provided with a main fuel needle 8 which slides upward by dint of pressure of needle control oil to be fed out of a needle control oil feeding port 5d and opens a main fuel injection passage 10. A seal is performed by seal oil to be fed out of the seal oil feeding port 5m installed in a valve body 5. Thus, no only sealability is improve but also the cost of production is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection valve for injecting and supplying fuel into the combustion chamber of a diesel engine, and particularly to a fuel injection valve for a direct injection type diesel engine.

[Conventional technology]

In the fuel injection valve of a direct injection diesel engine, when a gas with a high ignition temperature such as compressed natural gas is used as the main fuel, diesel oil, which is easy to ignite, is generally injected as a secondary fuel for ignition before the main fuel. The main fuel, which has a high ignition temperature, is ignited by the flame or high-temperature combustion gas.

Conventionally, these main fuel and auxiliary fuel have been injected from a main fuel injection valve and an ignition auxiliary fuel injection valve, respectively, which are respectively disposed within the combustion chamber.

For this reason, with respect to the spray of secondary fuel for ignition, there is a disadvantage that the ignition timing 2 ignition point and air usage range are different between the main fuel spray or jet near the secondary fuel injector and the spray or jet far away. be. In addition, in order to ignite each spray or jet of the main fuel at the same time, it is necessary to form a high-temperature region over a fairly wide range before injecting the main fuel, and therefore a large amount of auxiliary fuel is required. This was preferable because it tended to increase the fuel consumption rate of the engine.

In order to eliminate these drawbacks, the main fuel injection valve and the auxiliary fuel injection valve are integrated so that both fuels can be injected independently from almost the same location, thereby injecting as little fuel as possible. The secondary fuel creates suitable combustion conditions for the main fuel and ensures ignition,
A fuel injection valve for a direct injection diesel engine that reduces the fuel consumption rate is disclosed in Japanese Utility Model Application Publication No. 57-20868.

[Problem that the invention seeks to solve]

However, in the fuel injection valve disclosed in the above-mentioned Japanese Utility Model Publication No. 57-20868, the auxiliary fuel needle that opens and closes the auxiliary fuel injection passage is inserted into the hollow hole of the main fuel needle that opens and closes the main fuel injection passage. Since both the main and auxiliary fuel needles are arranged adjacent to each other, the main fuel or the auxiliary fuel can easily flow into the injection passage of the separate system. In order to prevent this, the lower end of each needle is pressed against each valve seat with a fairly high pressure, but there are still some problems with sealing performance, and further improvement has been desired. In addition, it is necessary to improve the machining accuracy of each sliding part of the main and auxiliary fuel needles, resulting in an increase in cost.

The present invention solves these problems, prevents the main fuel or the auxiliary fuel from flowing into the injection passage of another system, improves the sealing performance of the sliding part of the main fuel needle, and improves the sealing performance of the main fuel needle. It is an object of the present invention to provide a fuel injection valve in which the machining accuracy of each sliding portion of the needle for both auxiliary fuels is lowered to reduce costs.

[Means for solving problems]

In order to achieve such an object, the present invention provides a fuel injection valve that uses a main fuel consisting of a high-h gas with a high ignition temperature and an auxiliary fuel that ignites the main fuel. a valve body having a needle control oil supply port formed in the small diameter part, and a valve body that is fitted into a hollow hole formed in the axial center of the valve body and slid upward by the pressure of the secondary fuel. An auxiliary fuel needle that opens a fuel injection passage, and a needle control that is fitted into a small diameter portion and a large diameter portion of the valve body, respectively, and between an inner circumferential surface fitted into the large diameter portion and the small diameter portion. a main fuel needle that forms a space facing the oil supply port and slides upward under the pressure of the needle control oil supplied from the needle control oil supply port to open the main fuel injection passage; The sliding portion of the valve body of the valve needle is sealed with seal oil supplied from a seal oil supply port provided in the valve body.

[For production]

According to the above configuration, when the auxiliary fuel needle is slid upward by the pressure of the auxiliary fuel, the auxiliary fuel injection passage is opened and the auxiliary fuel is injected from the auxiliary fuel injection passage. Further, the main fuel needle is slid upward by the pressure of the needle control oil supplied from the needle control oil supply port, the main fuel injection passage is opened, and the main fuel is injected from the main fuel injection passage. Further, the sliding portion of the main fuel needle with respect to the valve body is sealed with seal oil supplied from the seal oil supply port of the valve body.

〔Example〕

The present invention will be explained below based on embodiments shown in the drawings.

The drawing shows a longitudinal cross-sectional view of a fuel injection valve according to the present invention, in which a fuel injection valve 1 is installed in a combustion chamber (not shown) of a diesel engine, and includes an outer cylinder 2 and an inner cylinder 3. , an atomizer 4, a valve body 5, an auxiliary fuel needle 6, and a main fuel needle 8.

The outer cylinder 2 is fixed to a cylinder cover (not shown), and the inner cylinder 3 is housed in the hollow part 2a of the outer cylinder 2, and the flange part 3a of the inner cylinder 3 is fixed to the upper surface of the outer cylinder 2 with bolts 9. has been done. The atomizer 4 is inserted and fixed into an opening 2b formed at the lower end of the outer cylinder 2, and includes an injection passage 10 and its injection port 10a for main fuel, for example, high-pressure gas, and an injection passage 12 and its injection port 12a for the auxiliary fuel. are formed separately.

The valve body 5 has a first valve body 5A that is inserted and fixed into the hollow part of the inner cylinder 3, and a lower surface of the first valve body 5A and a lower surface of the first valve body 5A and a lower end thereof between the first valve body 5A and the atomizer 4. It consists of a second valve body 5B disposed in contact with the upper surface of the eyeizer 4, and the second valve body 5B has small diameter portions 5a at the top and bottom.

5b, a large diameter portion 5C is formed in the middle portion,
Needle control oil supply ports 5d and 5e are formed in the small diameter portions 5a and 5b, respectively, in proximity to the large diameter portion 5C. Further, an auxiliary fuel passage 5h communicating with the auxiliary fuel injection passage 12 of the atomizer 4 is formed in the lower part of the second valve body 5B.

The auxiliary fuel needle 6 includes a first auxiliary fuel needle 6A that is slidably inserted into a hollow hole formed in the axial center of the first valve body 5A, and a shaft of the second valve body 5B. A second auxiliary fuel needle 6B is slidably inserted into a hollow hole formed in the core and integrally connected to the first auxiliary fuel needle 6A.
These first and second auxiliary fuel needles 6A.

An auxiliary fuel passage 6a is formed in communication with the narrow part of the second auxiliary fuel needle 6B, and a plurality of branched auxiliary fuel passages branched from the auxiliary fuel passage 6a are formed on the lower outer peripheral surface of the second auxiliary fuel needle 6B. 6b is formed. First auxiliary fuel needle 6A
is pressed downward by a compression spring 16 wrapped around the shaft 15 & of a fixing member 15 fixed in the hollow part of the first valve body 5 above, and as a result, the second auxiliary fuel The tapered portion 6C formed at the lower end of the needle 6B is the i! formed at the lower end of the hollow hole of the second valve body 5B. O fixing member 15 that comes into contact with ill fuel valve seat 51
An auxiliary fuel passage 15C is formed in the lower axial center of the fuel tank 1, which communicates with an auxiliary fuel supply port (not shown) and an auxiliary fuel passage 5a of the first auxiliary fuel needle 6A.

The main fuel needle 8 includes first and second main fuel needles 8A and 8 that are slidably inserted into the second valve body 5B.
The sliding surface of these main fuel needles 8A and 8B with the second valve body 5B has a seal introduced from the seal oil inlet 5j formed in the first valve body 5A. The oil passes through the seal oil passages 5k formed along the respective axes of the first and second valve bodies 5A and 5B, and through the plurality of seal oil supply ports 5 formed in the second valve body 5A. The supply is now available.

C, needle control oil as seal oil,
Common lubricants or secondary fuels are used.

However, when using special fuels as sub-fuels, such as by-product oils derived from oil and gas, control oils are also used as sub-fuels, as they have poor compatibility with general lubricating oils used in engines. Experiments have shown that it is necessary to do so.

The first main fuel needle 8A is housed in the hollow part 2& of the outer cylinder 2 and is pressed downward via a spring receiver 23 by a compression ring 22 wrapped around the shaft part 3bK of the inner cylinder 3. Second
A tapered part 8a is formed at the lower end of the second main fuel needle 8B, and a through hole 8b is formed in the tapered part 8a, and the lower end of the second main fuel needle 8B is used for the main fuel injection of the atomizer 4. It comes into contact with a main fuel valve seat 10b formed at the open end of the passage 10.

As shown in the drawing, the first and second main fuel needles 8A, 8B are pressed downward by the spring force of the compression spring 22, and the main fuel valve seat 10b is pushed under the second main fuel needle 8B. In the closed state, the second valve body 8
There is also a space 25 where the upper control oil supply port 5d faces between the upper small diameter portion 5a of B and the inner peripheral surface 8C of the first main fuel needle 8A fitted into the large diameter portion 5C. A space 26 where the lower needle control oil supply port 5e faces between the lower small diameter portion 5b of the second valve body 8B and the inner peripheral surface 8d of the second main fuel needle 8B fitted into the large diameter portion 5C. are formed respectively. Further, a space 28 is formed between the tapered portion 5n formed on the lower outer circumferential surface of the second valve body 5B and the inner circumferential surface of the tapered portion 8a of the second main fuel needle 8B.

A space, that is, a main fuel passage 30 is formed between the outer peripheral surfaces of the first and second main fuel needles 8A, 8B and the inner peripheral surface of the outer cylinder 2. Further, the outer cylinder 2 is formed with a main fuel supply port 2b that communicates with the hollow portion 2a and supplies main fuel to the main fuel passage 3°.

Next, the operation of the embodiment of the present invention will be explained.

When the secondary fuel is supplied from the fuel injection pump to the secondary fuel supply port at a predetermined timing in the valve closed state shown in the drawing,
This auxiliary fuel is introduced into the auxiliary fuel passage 6a and the branched auxiliary fuel passage 6b of the auxiliary fuel needle 6, and the pressure of the auxiliary fuel pushes up the auxiliary fuel needle 6 against the spring force of the compression spring 16. The auxiliary fuel passage 5h of the second valve body 5B is opened, and a predetermined amount of auxiliary fuel is injected into the surrounding area from the injection port 12a via the auxiliary fuel injection passage 12. Around the same time as this injection,
Needle control oil supply port 5d space 25
The first main fuel needle 8A is pushed up against the spring force of the compression spring 22 by the pressure of the needle control oil supplied to the needle control oil, and the second main fuel needle 8A is pushed up by the high pressure gas supplied from the main fuel supply port 2b. Main fuel needle 8
B receives back pressure and is pushed up following the first main fuel needle 8A, opens the main fuel injection passage 10, and a predetermined amount of high pressure gas is injected into the surrounding area from the injection port 10a. That is, in this embodiment, the auxiliary fuel and the high-pressure gas are completely independent from each other, and each injection port 10a is placed close to the center of the injection port 10a.
12a, in other words, it can be injected from approximately the same position.

High-pressure gas may flow into the sliding surface between the second valve main body 5B and the second main fuel oil supply port 5e, but this high-pressure gas flows outside from the lower needle control oil supply port 5e. It is discharged. Further, the first main fuel needle 8A that has risen when the valve is opened tries to descend due to the pressure of the compression spring 22 when the supply of needle control oil from the upper introduction 5d is stopped. If the main fuel needle 8B is stuck to the second valve body 5B and the sliding resistance is large, the second main fuel needle 8B cannot be lowered by the pressure of the compression spring 22 alone. As a result, the valve remains open, and more fuel than necessary is supplied to the combustion chamber, resulting in abnormal operating conditions of the diesel engine. In such a case, it is necessary to urgently normalize the operating state of the diesel engine, and the needle control oil flows out from the lower slot 5e into the space 26, and the pressure of the needle control oil is added to the pressure of the compression spring 22. The second main fuel needle 8B is lowered by the pressure, and the main fuel valve seat 10b is closed by the lower surface of the second main fuel needle 8B, resulting in a closed 1 valve state.

In addition, the sliding part of the main fuel needle 8 with the second valve body 5B is sealed with seal oil, so that the main fuel does not flow into the needle control oil supply port for a few seconds.
Therefore, the main fuel needle 8 can be reliably operated.

〔Effect of the invention〕

As described above, according to the present invention, since the valve body is interposed between the main fuel needle and the auxiliary fuel needle,
The main fuel and the auxiliary fuel are completely separated, improving sealing performance, and there is no need to increase the machining accuracy of the sliding surfaces of the main fuel needle and the auxiliary fuel needle, thereby reducing costs. Furthermore, since the main fuel does not flow into the needle control oil supply port, the main fuel needle can always operate normally.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a fuel injection valve according to the present invention. DESCRIPTION OF SYMBOLS 1... Fuel injection valve, 5... Valve main body consisting of 1st and 2nd valve main bodies 5A, 5B, 5a... Small diameter part. 5c-0, large diameter section, 5d...needle control oil supply port, 5m...seal oil supply port. 6. Needle for secondary fuel, 8. Needle for main fuel. 8C...inner peripheral surface, 10...main fuel injection passage. 12... Sub fuel injection passage, 25... Space.

Claims (2)

[Claims] (1) In a fuel injection valve that uses a main fuel consisting of a gas with a high ignition temperature and an auxiliary fuel that ignites this main fuel,
A valve body having a small diameter portion, a large diameter portion formed below the small diameter portion, and a needle control oil supply port formed in the small diameter portion; an auxiliary fuel needle that slides upward under the pressure of the auxiliary fuel to open the auxiliary fuel injection passage; and an inner periphery that is fitted into the small diameter portion and the large diameter portion of the valve body, respectively, and is fitted into the large diameter portion. A space facing the needle control oil supply port is formed between the surface and the small diameter portion, and the needle control oil is slid upward by the pressure of the needle control oil supplied from the needle control oil supply port to open the main fuel injection passage. A main fuel needle is provided, and a sliding portion of the main fuel needle with the valve body is sealed with seal oil supplied from a seal oil supply port provided in the valve body. fuel injection valve. (2) The fuel injection valve according to claim 1, wherein the seal oil is the needle control oil, the auxiliary fuel, or the lubricating oil.