JPH04259662A - Multi-jet type two-step injecting automatic fuel injector of diesel engine - Google Patents

Abstract

PURPOSE:To prevent bluish white smoking resulting from drop of the penetration force of the injected fuel in the condition that the injection is made with minor quantity and low pressure at the time of low load bearing. CONSTITUTION:A nozzle valve 6 is formed by fitting a cylindrical nozzle valve 6b for low pressure on a nozzle valve 6a for high pressure with possibility of sliding with the tightness held. The high pressure nozzle valve 6a is put by a valve shutting spring for high pressure 7 in closed contact with a valve seat for high pressure 3a, while the low pressure nozzle valve 6b put by a low pressure valve shutting spring 8 in closed contact with a valve seat for low pressure 3b. A working chamber 2 for valve opening consists of a high- pressure valve opening chamber 2a situated between the two valve seats 3a, 3b and a low-pressure valve opening chamber 2b located at the periphery of the low pressure valve seat 3b. At this low-pressure valve opening chamber 2b, a plurality of jets 9 for low pressure are opened. The fuel is injected only from these low pressure jets 9 having a minor bore in the condition that the injection is made in a minor quantity and with low pressure at the time of low load bearing, which should ensure securing the penetration force.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-hole two-stage automatic fuel injector for diesel engines.

0002

[Prerequisite Structure] The multi-hole two-stage automatic fuel injector for a diesel engine of the present invention is predicated on having the following prerequisite structure, as shown in FIG. 1 or 3, for example. That is, inside the nozzle body 1 of the multi-hole nozzle, a valve opening operating chamber 2, a valve seat 3, a flow dividing chamber 4, and a plurality of jet ports 5 arranged in the circumferential direction are provided in order to communicate with each other. A nozzle valve 6 is inserted into the hole. And this nozzle valve 6
In this case, the high-pressure valve-closing spring 7 and the low-pressure valve-closing spring 8 are brought into valve-closing contact with the valve seat 3, whereas the low-pressure valve-closing spring 8 is first brought into contact with the fuel pressure in the valve-opening working chamber 2. The valve is opened against the pressure, and then the high pressure valve closing spring 7 is used to open the valve. This prerequisite structure has the advantage of preventing diesel knock. At the start of injection, the opening amount of the nozzle valve 6 is small and the injection pressure is low, so the injection amount is small, and the amount of accumulated fuel injected during the ignition delay period is small, making diesel knock less likely to occur.

0003

2. Description of the Related Art In the above-mentioned prerequisite structure, a specific structure for two-stage injection of fuel is shown in FIG. 3 in the prior art. That is, the nozzle valve 6 is urged toward the valve closing side by the high pressure valve closing spring 7 via the low pressure valve closing spring 8 and the high pressure spring receiver 7a in this order. The high pressure spring receiver 7a is received by the stopper 7b during the valve closing stroke. The nozzle valve 6 comes into contact with the high pressure spring receiver 7a during the valve opening stroke. In the process of increasing the pressure in the valve opening working chamber 2, the low valve opening setting pressure P1 (for example, 180 kg/cm2
. Then, when the high pressure valve opening setting pressure P2 (for example, 230 kg/cm2) is exceeded, the nozzle valve 6 resists the high pressure valve closing spring 7 and becomes fully open.

0004

[Problem to be solved by the invention] In the above conventional technology,
There is a problem in that blue and white smoke is likely to be generated when the load is light or no load. When the engine is under rated load, the amount of fuel injected is large and the fuel is injected at a high pressure state where the injection pressure is higher than the high pressure valve opening setting pressure P2. The diameter D1 of each nozzle port 5 is set to a size that achieves both the injection rate and penetration force of the injected fuel in the high-pressure injection state at the rated load. However, when the load is light or no load, the injection amount is small and the injection pressure is injected at a low pressure that does not reach the high pressure valve opening setting pressure P2. For this low-pressure injection state, the size of the diameter D1 of the nozzle 5 is too large, so the penetration force of the injected fuel becomes too weak, the mixing performance deteriorates, and blue-white smoke is likely to occur. It is. The present invention aims to prevent the generation of blue-white smoke due to a decrease in the penetration force of the injected fuel at light loads or no loads, while maintaining the injection rate and penetration force of the injected fuel appropriately at the rated load. Take it as a challenge.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the present invention is characterized by adding the following characteristic structure to the above-mentioned prerequisite structure, as shown in FIGS. 1 and 2, for example. That is, in the nozzle valve 6, a cylindrical low-pressure nozzle valve 6b is fitted onto the high-pressure nozzle valve 6a in a sealed and slidable manner. Further, the valve seat 3 is formed by providing a low pressure valve seat 3b on the outer periphery of a high pressure valve seat 3a. The high-pressure nozzle valve 6a is brought into closing contact with its high-pressure valve seat 3a by a high-pressure valve closing spring 7, whereas the low-pressure nozzle valve 6b is brought into close contact with its low-pressure valve seat 3a by a low-pressure valve closing spring 8. 3b to make a closing contact. Valve opening operating chamber 2
is between this high pressure valve seat 3a and this low pressure valve seat 3b,
A high-pressure valve opening working chamber 2a is formed, and a low-pressure valve opening working chamber 2b is formed on the outer periphery of the low-pressure valve seat 3b. The high-pressure valve-opening working chamber 2a is configured with a plurality of low-pressure nozzles 9 opened in parallel in the circumferential direction of the chamber.

[0006]

[Operation] The present invention operates as follows. When the engine is under rated load, the fuel injection amount is large, so the valve-opening working chamber 2 enters a high-pressure injection state equal to or higher than the high-pressure valve-opening set pressure P2, and both the low-pressure nozzle valve 6b and the high-pressure nozzle valve 6a are fully opened. Fuel is injected from both the injection ports 5 and each low pressure injection port 9. The diameter D1 of each nozzle 5 and the diameter D2 of each low-pressure nozzle 9 are set to dimensions that achieve both the injection rate and penetration force of the injected fuel in this large-volume, high-pressure injection state at the rated load. . When the engine is under light load or no load, the fuel injection amount is small, so the valve opening working chamber 2 is in a low pressure injection state, which is higher than the low pressure valve opening setting pressure P1 but lower than the high pressure valve opening setting pressure P2, Only the low-pressure nozzle valve 6b opens, and fuel is injected only from each low-pressure injection port 9. The diameter D2 of each low-pressure injection port 9 is set to a small size commensurate with the small fuel injection amount during light load or no-load conditions, so that the straight-line performance of the injected fuel is improved. As a result, sufficient injection rate and penetration force of the injected fuel can be ensured even in a low pressure injection state under light load or no load.

[0007]

[Effects of the Invention] The present invention has the following effects because it is constructed and operates as described above. In the high-volume, high-pressure injection state at the rated load of the engine, each nozzle 5... and each low-pressure nozzle 9
Since fuel is injected from both sides, the injection rate and penetration force of the injected fuel are compatible, and good combustion performance can be ensured. Moreover, in a small amount, low pressure injection state under light load or no load, fuel is injected only from each small-diameter low-pressure nozzle 9..., so the injection rate and penetration force of the injected fuel can be ensured sufficiently, and the mixing performance can be improved. and the generation of blue-white smoke can be significantly reduced or prevented.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. Fig. 1 is a longitudinal cross-sectional view of a multi-hole two-stage automatic fuel injector for a diesel engine, and Fig. 2 (A) is a longitudinal cross-sectional view of a main part of a multi-porous two-stage automatic fuel injector for a diesel engine. 2(B) is a sectional view taken along the line X--X in FIG. 2(A). In the figure, inside a nozzle body 1 of a multi-hole nozzle, a valve opening operating chamber 2, a valve seat 3, a flow dividing chamber 4, and a plurality of nozzles 5 arranged in the circumferential direction are provided in order to communicate with each other.
A nozzle valve 6 is inserted inside. This valve seat 3 is formed by providing a low pressure valve seat 3b on the outer periphery of a high pressure valve seat 3a. In the nozzle valve 6, a cylindrical low-pressure nozzle valve 6b is fitted onto the high-pressure nozzle valve 6a in a sealed and slidable manner. This high pressure nozzle valve 6a is connected to the high pressure valve seat 3a by the high pressure valve closing spring 7 via the low pressure valve closing spring 8 and the high pressure spring receiver 7a in this order.
The valve is brought into contact with the valve to close it, and the valve is pressed toward the valve-closing side. Further, the low pressure nozzle valve 6b is brought into close contact with the low pressure valve seat 3b by a low pressure valve closing spring 8. The high-pressure spring receiver 7a is received by the stopper 7b during the valve closing stroke. Further, the low pressure nozzle valve 6b is connected to the high pressure spring receiver 7a via the high pressure nozzle valve 6a during the valve opening stroke.
, and is pressed by the high pressure valve closing spring 7. The valve-opening working chamber 2 forms a high-pressure valve-opening working chamber 2a between the high-pressure valve seat 3a and the low-pressure valve seat 3b, and a low-pressure opening on the outer periphery of the low-pressure valve seat 3b. Valve working chamber 2
b is formed. The high-pressure valve-opening working chamber 2a is configured with a plurality of low-pressure nozzles 9 opened in parallel in the circumferential direction of the chamber. The diameter D1 of each nozzle 5 and the diameter D2 of each low-pressure nozzle 9 are set to dimensions that achieve both the injection rate and penetration force of the injected fuel in a large-volume, high-pressure injection state at rated load, and , the diameter D2 of each low-pressure injection port 9 is set to a small size suitable for a small fuel injection amount under light load or no load. The nozzle body 1 is
It is tightened and fixed to a nozzle holder 11 with a cap nut 10.

In the above embodiment of the present invention, the fuel pumped from the fuel pump (not shown) comes from the direction of the arrow in the figure, and in the process of increasing the pressure in the low pressure valve opening working chamber 2b, the low pressure valve opening is performed. Set pressure P1 (e.g. 180 kg/cm2
), the low pressure nozzle valve 6b closes the low pressure valve closing spring 8.
The valve is opened against the high pressure nozzle valve 6a and is received by the high pressure spring receiver 7a to maintain the valve in a half-open state. When the fuel injection amount is large and the fuel pressure is high, such as when the engine is under rated load, the high-pressure valve opening setting pressure P2 (for example, 230 kg/cm2) is exceeded, and the high-pressure nozzle valve 6a is connected to the high-pressure valve closing spring 7. The valves are fully opened, and both the low-pressure nozzle valve 6b and the high-pressure nozzle valve 6a are fully opened, and each injection port 5
... and each low pressure injection port 9... fuel is injected from both. On the other hand, when the engine is under light load or no load, the fuel injection amount is small, so the low-pressure valve opening working chamber 2b is injected with low-pressure injection, which is higher than the low-pressure valve-opening set pressure P1 but lower than the high-pressure valve-opening set pressure P2. state, only the low-pressure nozzle valve 6b opens, and fuel is injected only from each low-pressure injection port 9. The diameter D2 of each low-pressure injection port 9 is set to a small size that corresponds to the small amount of fuel injection at light load or no load, so even in the low pressure injection state at light load or no load, the injected fuel Sufficient injection rate and penetration force are ensured. Therefore, the atomization characteristics of the fuel are improved, the combustion performance is enhanced, and the problem of blue-white smoke is eliminated.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIG. 1 is a longitudinal sectional view of a multi-hole two-stage automatic fuel injector for a diesel engine.

2 shows an embodiment of the present invention, FIG. 2(A) is a longitudinal cross-sectional view of a main part of a multi-hole two-stage automatic fuel injector for a diesel engine, and FIG. 2(B) is a - It is an X-ray arrow sectional view.

FIG. 3 is a diagram showing a conventional example and corresponding to FIG. 1;

[Explanation of symbols]

1... Nozzle body, 2... Working chamber for valve opening, 2a... Working chamber for high pressure valve opening, 2b... Working chamber for low pressure valve opening, 3... Valve seat, 3a... Valve seat for high pressure, 3b... Valve seat for low pressure, 4... Diversion chamber, 5... Nozzle,
6... Nozzle valve, 6a... Nozzle valve for high pressure, 6b... Nozzle valve for low pressure, 7... Valve closing spring for high pressure, 8... Valve closing spring for low pressure, 9
...Low pressure nozzle.

Claims (1)

[Claims] [Claim 1] Inside the nozzle body (1) of the multi-hole nozzle, a valve opening operating chamber (2), a valve seat (3), a diversion chamber (4),
A plurality of nozzle ports (5...) arranged in the circumferential direction are provided in order to communicate with each other, and a nozzle valve (6) is inserted into this nozzle body (1), and this nozzle valve (6) is equipped with a high pressure valve closing spring ( 7) and the low pressure valve closing spring (8) are brought into valve closing contact with the valve seat (3), whereas the low pressure valve closing spring (8) is first brought into contact with the fuel pressure in the valve opening working chamber (2). In the multi-hole two-stage automatic fuel injector for a diesel engine, the nozzle valve (6) is configured to open the valve against the pressure of the nozzle valve (6) and then open the valve using the high-pressure valve closing spring (7). is the high pressure nozzle valve (6a
) is fitted with a cylindrical low pressure nozzle valve (6b) in a sealed and slidable manner, and the valve seat (3) has a low pressure valve seat (3b) on the outer periphery of the high pressure valve seat (3a). The high-pressure nozzle valve (6a) is brought into closing contact with the high-pressure valve seat (3a) by the high-pressure valve closing spring (7), whereas the low-pressure nozzle valve (6b) , the low pressure valve closing spring (8) is brought into close contact with the low pressure valve seat (3b), and the valve opening working chamber (2) is connected to the high pressure valve seat (3a) and the low pressure valve seat (3a). A high-pressure valve opening working chamber (2a) is formed between the high-pressure valve seat (3b) and a low-pressure valve-opening working chamber (2b) is formed on the outer periphery of the low-pressure valve seat (3b). A multi-hole two-stage injection fuel automatic for a diesel engine, characterized in that a valve opening working chamber (2a) has a plurality of low pressure nozzles (9...) opened in parallel in the circumferential direction of the chamber. Injector.