JPH0417811Y2 - - Google Patents

Description

[Detailed explanation of the idea] Industrial applications The present invention relates to a fuel injection valve for an internal combustion engine.

BACKGROUND OF THE INVENTION In order to obtain good combustion in a diesel engine, it is necessary to properly mix fuel and air injected into a combustion chamber. Therefore, in order to properly mix the injected fuel and air, there is a known fuel injection valve that constantly gives a swirling motion to the fuel injected from the fuel injection valve and injects the fuel in a conical shape from the nozzle of the fuel injection valve. Yes (see Japanese Patent Application Laid-open No. 104025/1983).

However, when the fuel is injected in a conical shape in this way, the penetration force of the injected fuel becomes weak, so although good combustion occurs when the engine is running at low speeds, there is a problem that good combustion cannot be obtained when the engine is running at high speeds. In other words, when the engine rotates at high speeds, the time from when fuel is injected until it ignites is short, and in order to spread the injected fuel throughout the combustion chamber during this rectangular time and to mix the injected fuel and air sufficiently. It is necessary to increase the penetration force of the injected fuel to increase the distance that the injected fuel travels in the direction of the injection axis. On the other hand, when the engine speed is low, the time from when the fuel is injected until it ignites is longer, so if the penetration force of the injected fuel is increased at this time, the diffused fuel will adhere to the wall surface of the fuel chamber, resulting in a large amount of smoke. will occur. Therefore, the penetration force of the injected fuel must be weakened when the engine rotates at low speeds.

Therefore, when the engine speed is low, swirling motion is applied to the fuel and the fuel is injected in a conical shape, thereby weakening the penetrating force of the injected fuel, and when the engine is running at high speeds, the penetrating force of the injected fuel is strengthened by not giving swirling motion to the fuel. A fuel injection valve designed to
-Refer to Publication No. 60854). In this fuel injection valve, the tip of the needle is formed into a cylindrical shape, and a first injection port is formed in an annular shape around the tip of the cylindrical needle, and a second injection port is formed in the center of the tip surface of the cylindrical needle tip. A swirling chamber is formed in the tip of the needle that communicates with the second nozzle, and when the engine is running at low speeds, the fuel given a swirling motion in the swirling chamber is spouted out from the second nozzle while swirling, and when the engine is running at high speeds, the fuel is spouted out while swirling. Sometimes fuel is ejected from the first nozzle without swirling.

[Problem that the invention attempts to solve]

In this way, with this fuel injection valve, fuel is injected from the first nozzle when the engine is running at high speeds, and fuel is injected from the second nozzle when the engine is at low speeds, so high-speed or low-speed operation can be continued. Fuel is continuously injected from one nozzle, and fuel injection from the other nozzle continues to be stopped. However, if fuel injection from the nozzle continues to be stopped in this way, carbon etc. will gradually accumulate in the nozzle where fuel injection has been stopped, causing the nozzle to become clogged, making it difficult to inject fuel from this nozzle. This sometimes creates the problem that fuel cannot be injected.

[Means for solving problems]

In order to solve the above problems, the present invention includes a single nozzle and forms an annular swirling chamber around the tip of the needle, so that when the needle rises, the fuel swirling in the swirling chamber is transferred to the tip of the needle. In a fuel injection valve configured to swirl and inject fuel from a nozzle through a gap between valve seats, a first fuel passage communicating with a swirling chamber is formed in the needle, and a first fuel passage communicating with the swirling chamber is formed between the needle and the nozzle body. 2 fuel passages are formed, one of the first fuel passage and the second fuel passage is opened into the swirling chamber in the circumferential direction of the swirling chamber, and fuel is supplied into the first fuel passage and the second fuel passage. It is equipped with a flow divider to control the supply of water.

Embodiment FIG. 1 shows the entire fuel injection system when the present invention is applied to a diesel engine that uses normal light oil as fuel. The fuel injection device is broadly divided into a fuel injection pump 3, a flow divider 5, and a fuel injection valve 20. The fuel injection pump 3 is driven by the engine 4, and the suction side of the fuel injection pump 3 is connected to the light oil tank 1 via a pipe 72, a filter 2 with a drainer, and a pipe 70. A pipe 71 that communicates with the outside air extends from the filter 2 with a drainer. Further, the discharge side of the fuel injection pump 3 is connected to the inlet 10 of the flow divider 5 via a pipe 73 on the one hand, and a pipe 7 branched from the pipe 73 on the other hand.
4 to the other inlet 13 of the flow divider 5.

The flow divider 5 comprises a cylinder 6 and a piston 7 slidably inserted into the cylinder 6, and the piston 7 is normally moved into the cylinder 6 by the spring force of a compression spring 8.
It is brought into contact with the end surface 9 of. A branch passage 14 is formed in the piston 7 for discharging fuel flowing in one direction in two directions. Therefore, the fuel flowing in from the inlet 10 is selectively made to flow out from the first outlet 11 or the second outlet 12 by the branch passage 14 of the piston 7. On the other hand, in the flow divider 5 , an inlet 13 is formed in the cylinder 6 and opens onto the end surface 9 , and this inlet 13 is connected to a branch pipe 74 . When the pressure inside the pipe 73 increases, the piston 7 rises, and the divided flow rate flowing out from the first outlet 11 and the second outlet 12 is controlled.

The fuel injection valve 20 in FIG. 1 shows only the nozzle body 21 and the needle 22 slidably inserted into the nozzle body 21 in order to simplify the explanation. are essentially the same. FIG. 2 shows an enlarged view of the tip of the fuel injection valve 20, and the details of the structure will be described below with reference to FIG. A dome-shaped sac chamber 24 is formed at the lower end of the nozzle body 21, and a nozzle 2 that communicates with the engine combustion chamber is located within this sac chamber 24.
3 opens. A conical portion 2 having a substantially conical shape is disposed on the inner peripheral surface of the nozzle body 21 above the suction chamber 24.
5 is formed, and the conical tip 26 of the needle 22, which has a complementary shape to the conical part 25, is connected to the conical part 25.
It is brought into close contact with the seat portion 27 of. The needle 22 is normally urged downward by the spring force of a compression spring (not shown), and thereby the seat portion 27
However, when the pressure increases, the seat part 2
Fuel is ejected from the nozzle 23 away from the nozzle 7. Returning to FIG. 1 again, a fuel passage 28 is formed in the upper part of the nozzle body 21.
8 is connected to an annular passage 29 formed in the nozzle body 21 around the needle 22. On the other hand, a fuel passage 30 is formed in the needle 22 and extends perpendicularly to the central axis of the needle 22, and this fuel passage 30 is connected to the annular passage 29. Further, a first fuel passage 31 is formed within the needle 22 and extends on the central axis thereof. This first fuel passage 3
The upper end of the first fuel passage 31 is connected to a fuel passage 30, and the lower end of the first fuel passage 31 is communicated with a swirling chamber 36 formed around the needle 22 via a fuel passage 32. As shown in FIG. 3, the fuel passage 32 extends obliquely with respect to the radial direction of the needle 22, and therefore opens into the swirling chamber 36 in the circumferential direction of the swirling chamber 36. . Therefore, the swirling chamber 36 is connected from the first fuel passage 31 through the fuel passage 32.
The fuel supplied therein turns counterclockwise along the inner wall surface 37 of the turning chamber 36. Returning to FIG. 1 again, a fuel passage 33 is formed in the upper part of the nozzle body 21, and this fuel passage 33 is connected to a pressure chamber 34 formed around the needle 22.
The pressure chamber 34 is connected to an annular second fuel passage 35 formed between the inner peripheral surface of the nozzle body 21 and the outer peripheral surface of the needle 22, and this second fuel passage 35 is communicated with a swirling chamber 36. The fuel passage 28 communicating with the first fuel passage 31 is connected to the first outlet 11 of the flow divider 5 via a pipe 75, and the second fuel passage 35
The fuel passage 33 leading to is connected to the second outlet 12 of the flow divider 5 via a pipe 76 .

When the engine 4 starts operating, the fuel injection pump 3
rotates, and the light oil in the light oil tank 1 is force-fed to the flow divider 5 via the pipe 73. This light oil is inlet 1
0 into the branch passageway 14 formed in the piston 7. When the pumping of light oil is started, the pumping pressure of light oil is transmitted to another inlet 13 of the flow divider 5 via the pipe 74. At this time, if the engine speed is low, the spring force of the compression spring 8 that urges the piston 7 exceeds the pumping pressure because the pumping pressure is low, and as a result, the piston 7 remains in contact with the end surface 9 of the cylinder 6. Become. At this time, the branch passage 14 of the piston 7 is formed so that the inlet 10 and the first outlet 11 communicate with each other. Therefore, when the engine speed is low, inlet 1
0, most of the light oil introduced into the first outlet 11
The fuel is supplied through the pipe 75 into the fuel passage 28 of the fuel injection valve 20 . The light oil supplied to the fuel passage 28 passes through the annular passage 29 and the fuel passage 30 formed in the needle 22 and flows into the first fuel passage 31 formed on the central axis of the needle 22. Next, this light oil flows from the fuel passage 32 to the swirling chamber 3.
6, and as a result, swirling chamber 3
The light oil in 6 starts a swirling movement. Next, the pressure in the swirling chamber 36 increases due to the subsequent light oil pumped from the fuel injection pump 3, and this increased pressure is transmitted to the pressure chamber 34 via the second fuel passage 35. When the pressure within the pressure chamber 34 increases, the needle 22 rises against the spring force of a compression spring (not shown), the needle 22 separates from the seat portion 27, and light oil is jetted out from the spout 23. As described above, a swirling force is applied to the light oil in the swirling chamber 36, so when the needle 22 is raised, the light oil is spouted into the combustion chamber while swirling. As a result, the spread angle of the spray becomes larger and the penetration force of the injected fuel is weakened, so that the injected fuel is sufficiently mixed with air and atomization is promoted during low-speed operation where combustion takes place for a relatively long time. good combustion conditions can be obtained.

On the other hand, when the engine speed is high, the pressure of light oil discharged from the fuel injection pump 3 is higher than during low speed operation. The pressure applied to the inlet 13 of the flow divider 5 via the pipe 74 thus increases, as a result of which the piston 7 moves upwards against the compression spring 8. At this time, the branch passage 14 formed in the piston 7 is formed to communicate between the inlet 10 and the second outlet 12 and to block communication between the inlet 10 and the first outlet 11. Therefore, the light oil supplied into the inlet 10 at this time is transferred from the second outlet 12 to the pipe 7.
6 into the fuel passage 33 of the fuel injection valve 20. Next, this light oil fills the pressure chamber 34, the second fuel passage 35, and the swirling chamber 36, and the pressure gradually increases due to the light oil that subsequently flows in. When the pressure of the light oil in the pressure chamber 34 exceeds the spring force of a compression spring (not shown), the needle 22 rises and separates from the seat portion 27, and the light oil is spouted from the nozzle 23. The flow of light oil at this time is a straight flow along the central axis of the needle 22, unlike the case of the low-speed operation described above, and therefore no swirling flow is generated in the swirling chamber 36. Therefore, the light oil is injected into the combustion chamber without swirling, resulting in a spray with a strong penetrating force. As a result, during high-speed operation in which combustion is completed in a relatively short time, the spray quickly reaches a long distance, and in this way, sufficient air can be utilized, so that high output can be obtained.

Another embodiment of the invention is shown in FIGS. 4 and 5. In this embodiment, a needle 52 is slidably inserted into a nozzle body 51 of a fuel injection valve 50.
The conical tip of the needle 52 is normally a seat portion 55.
sit on top.

A sac chamber 54 is formed at the tip of the nozzle body 51, and a nozzle 53 opens into the sac chamber 54. A partition portion 61 that bulges outward is formed near the tip of the needle 52, and the swirl chamber 58 and the second fuel passage 56 are separated by the partition portion 61. This second fuel passage 56 is connected to the pressure chamber 34 (first
(Figure). An inclined groove 57 extending obliquely is formed on the outer circumferential surface of the partition portion 61.
opens into the swirling chamber 58 in the circumferential direction of the swirling chamber 58. Therefore, in this embodiment, a swirling flow is generated in the swirling chamber 58 by the light oil flowing out from the inclined groove 57. This second fuel passage 56 is connected to the first outlet 11 of the flow divider 5 via the pressure chamber 34 (FIG. 1).
connected to. On the other hand, the fuel passage 60 formed in the needle 52 extends in the radial direction of the needle 52, so that the light oil flowing out from the fuel passage 60 does not generate a swirling flow in the swirling chamber 58. This fuel passage 60 is connected to the second outlet 12 (FIG. 1) of the flow divider 5 via a first fuel passage 59 formed on the central axis of the needle 52. In this embodiment, light oil is supplied from the second fuel passage 56 when the engine rotates at low speeds to generate a swirling flow in the swirling chamber 58, and thus the light oil is spouted from the nozzle 53 while swirling. On the other hand, when the engine rotates at high speed, light oil is supplied from the first fuel passage 59 into the swirling chamber 58, and at this time, the light oil is jetted out from the injection port 53 without swirling.

Effects of the invention According to the invention, swirling fuel spray or non-swirling fuel spray can be selectively ejected from one nozzle. Therefore, since fuel is continuously injected from the nozzle, it is possible to prevent the nozzle from becoming clogged with carbon or the like.

[Brief explanation of the drawing]

Fig. 1 is an overall view of the fuel injection system when the present invention is applied to a diesel engine, Fig. 2 is an enlarged side sectional view of the tip of the fuel injector, and Fig. 3 is the − of Fig. 2.
4 is an enlarged side sectional view of another embodiment of the fuel injection valve, and FIG. 5 is a sectional view taken along the line - in FIG. 4. 3... fuel injection pump, 5... flow divider, 20...
...Fuel injection valve, 21... Nozzle body, 22...
Needle, 23... Spout, 28, 30, 32, 6
0... fuel passage, 31, 59... first fuel passage,
35, 56... Second fuel passage, 36, 58... Turning chamber.

Claims (1)

[Scope of utility model registration request] It is equipped with one nozzle and forms an annular swirling chamber around the tip of the needle, and when the needle rises, the fuel swirling in the swirling chamber is swirled from the nozzle through the gap between the needle tip and the valve seat. In this fuel injection valve, a first fuel passage communicating with the swirling chamber is formed in the needle, and a second fuel passage communicating with the swirling chamber is formed between the needle and the nozzle body, A flow divider that opens either the first fuel passage or the second fuel passage into the swirling chamber in the circumferential direction of the swirling chamber and controls the supply of fuel into the first fuel passage or the second fuel passage. A fuel injection valve for an internal combustion engine equipped with.