JPH0361028B2 - - Google Patents

Description

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

A conventional fuel injection valve of this type is shown in FIG. In the figure, 01 is the fuel injection valve body, 02 is the oil passage inside the fuel injection valve, and 03 is the needle valve.
is slidably inserted within. 04 is a needle valve push rod, 05 is a needle valve spring, and the spring force is applied to the needle valve 03 via the push rod 04 to the valve seat 01 provided inside the nozzle 08.
Pressing to 02. 06 is valve opening pressure adjustment screw, 0
7 is a spring chamber. The nozzle 08 communicates the oil reservoir 0101 with a combustion chamber (not shown) in the cylinder of the engine. 09 is a discharge port.

The fuel oil, which is good for the fuel injection pump (not shown), is compressed and becomes high pressure while flowing into the injection pipe (not shown).
through the oil passage 02 in the fuel injection valve to the oil sump 0.
It reaches 101. The needle valve 03 is pressed against the valve seat 0102 by a spring 05, and is opened so that it does not rise, that is, does not open, unless the fuel oil pressure in the oil reservoir 0101 reaches a certain pressure, that is, the valve opening pressure P ₀ or higher. The initial spring force is set by the valve adjustment screw 06. Therefore, the high pressure wave sent from the fuel injection pump reaches the valve opening pressure P ₀ at the oil sump 0101.
When the pressure exceeds 0, the needle valve 03 rises and the oil sump becomes 0.
The volume of part 101 increases, part of the fuel sent from the fuel injection pump is spent on this, and the rest is injected from nozzle 08 into the combustion chamber where it is ignited and combusted to produce output. When the fuel injection pump finishes discharging, the pressure in the oil sump 0101 drops, and when this pressure falls below the valve closing pressure, the needle valve 03 is pressed down by the spring 05 and lowers, causing the oil sump 0101 to close. The volume decreases, a part of which is injected from the nozzle 08, and the needle valve 03
When the fuel is seated on the valve seat 0102, the injection ends. Note that leakage from the sliding portion of the needle valve 03 during this period reaches the spring chamber 07 and is discharged through the discharge port 09.

However, the above method has the following drawbacks.

In order to reduce the combustion noise of diesel engines, it is necessary to reduce the amount of fuel during the ignition delay period, and one method to achieve this from the fuel injection side is to reduce the injection rate at the initial stage of injection. It is said that it is effective to suppress the With conventional models, the volume of the oil reservoir increases as the needle valve rises, so part of the fuel delivered from the fuel injection pump is used for this, and the rest is injected from the nozzle, so the injection at the initial stage of injection is reduced. On the other hand, when the needle valve descends due to a decrease in pressure, the volume of the oil reservoir decreases, and some of it is injected by the nozzle, so even in the latter half of the injection after the end of the main injection, the As shown, the injection at low pressure and low injection rate continues sluggishly, which has the disadvantage of worsening smoke exhaust, etc.

The purpose of the present invention is to focus on the above-mentioned points, to suppress the injection rate at the initial stage of injection, that is, to ensure a long period of low injection rate, and to prevent injection at a low pressure and low injection rate in the latter stage after the end of main injection. The purpose of the present invention is to provide a fuel injection valve that can improve the cutting of fuel, and its features include an oil sump in the main needle valve into which fuel from the fuel injection pump is introduced, and a combustion chamber between the oil sump and the cylinder. In a fuel injection valve for an internal combustion engine, which has a nozzle communicating with a chamber, and a main needle valve that opens and closes the nozzle by attaching to and detaching from a valve seat provided inside the nozzle, the fuel injection valve has a main needle valve that slides into the space around the main needle valve. an auxiliary needle valve that is movably housed and has an oil sump on one end and a spring on the other end, and oil that is branched by a fuel introduction path to the oil sump of the main needle valve and reaches the oil sump of the auxiliary needle valve. a check valve installed in the oil passage and urging the secondary needle valve in a direction to increase the volume of the oil reservoir in the secondary needle valve; The present invention is equipped with a throttle that gradually reduces the pressure in the oil reservoir of the sub-needle valve.

In this case, by combining the secondary needle valve with a check valve and a throttle that control this movement, (2) In the latter stage of injection, after the main needle valve is seated, the secondary needle valve is
Displace it in the opposite direction to (1).

Note that if the shape is such that two valves are combined coaxially, the configuration becomes compact and space-saving.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view showing one embodiment of a fuel injection valve according to the present invention.

In the figure, 1 is the fuel injection valve body, 2 is an oil passage that introduces fuel from the fuel injection pump into the oil reservoir 101 of the main needle valve, and 3 is the main needle valve, which is slidably inserted into the fuel injection valve body 1. has been done. 4 is the main needle valve push rod,
Reference numeral 5 denotes a main needle valve spring, and the spring force presses the main needle valve 3 against a valve seat 102 provided inside the spout 8 via a push rod 4. 6 is a valve pressure adjustment screw, and 7 is a spring chamber. The injection port 8 communicates between the oil reservoir 101 of the main needle valve and a fuel chamber (not shown) in the cylinder of the engine. 9 is a discharge port.

Reference numeral 13 denotes a sub-needle valve, which is slidably housed in a space around the main needle valve, and has an oil reservoir 16 for the sub-needle valve at one end and a sub-needle valve spring 14 at the other end. 15 is an auxiliary needle valve stopper.

Reference numeral 10 indicates a check valve, and reference numeral 12 indicates a throttle, both of which are arranged in parallel in the middle of an oil passage that branches from the oil passage 2 via an annular oil passage 17 and reaches an oil reservoir 16 of the auxiliary needle valve. 11 is a check valve spring.

The operation in the case of the above configuration will be described.

The fuel oil is compressed by the fuel injection pump (not shown) and becomes high pressure, while the injection pipe (not shown)
The oil is sent to the fuel injection valve, passes through the oil passage 2 in the fuel injection valve, and is branched off at the annular oil passage 17, one of which is connected to the oil sump 10 of the main needle valve.
It reaches 1.

The main needle valve 3 is pressed by the main needle valve spring 5, and the auxiliary needle valve 13 is pressed by the width needle valve spring 14, and will not rise unless the pressure exceeds a certain pressure, that is, the valve opening pressure _P0 . Therefore, the high pressure wave sent from the fuel injection pump increases the valve opening pressure at the main needle valve oil reservoir 101.
When P ₀ or more, the main needle valve 3 rises, and at this time the check valve 10 opens, so the throttle 12 does not operate.
When the pressure in the main needle valve oil reservoir 101 reaches P ₀ , the pressure in the auxiliary needle valve oil reservoir 16 also reaches P ₀ , and the auxiliary needle valve 13 also rises at almost the same time as the main needle valve 3 . Therefore, the increase in volume when the needle valve 3 is raised is the sum of the increases in the oil reservoirs 101 and 16, and becomes larger. As the main needle valve 3 rises, fuel is injected from the nozzle 8 into a fuel chamber (not shown) in the cylinder of the engine, where it is ignited and combusted to produce output.

When the fuel injection pump finishes discharging, the pressure in the main needle valve oil reservoir 101 decreases, and when this pressure falls below the valve closing pressure, the main needle valve 3 is pressed by the main needle valve spring 5 and lowered. Take a seat. On the auxiliary needle valve side, when the fuel injection pump finishes discharging and the pressure in the oil passage decreases, the check valve 10 is closed by the check valve spring 11 and the fuel is throttled by the throttle 12. Therefore, the pressure drop in the secondary needle valve oil reservoir 16 becomes gradual, and the rate of pressure drop is controlled by appropriate selection of the size and shape of the throttle. If the pressure is lower than the valve closing pressure, the auxiliary needle valve 13 will be lowered after the main needle valve 3 is seated.
Therefore, the fuel corresponding to the change in volume when the auxiliary needle valve 13 descends is not injected from the injection port 8. Note that leakage from the sliding parts of the main needle valve 3 and the auxiliary needle valve 13 during this period reaches the spring chamber 7 and is discharged through the discharge port 9. In addition, if the shape of the secondary needle valve 13 is made conical at the bottom and the cone is seated, the closing pressure can be made smaller than the opening pressure, and the lowering of the secondary needle valve 3 starts. It is even more effective because it can slow down the process.

The above effects can be summarized with a focus on the fuel injection rate as follows.

(1) At the beginning of injection, the main and auxiliary needle valves rise almost simultaneously, resulting in a large increase in volume, and a large portion of the fuel sent from the fuel injection pump is spent on this purpose. Therefore, the injection rate at the initial stage of injection is suppressed low.

(2) In the latter stage of injection, the secondary needle valve descends after the main needle valve is seated, so the change in solution is not related to fuel injection. Therefore, it is possible to prevent the low-pressure, low-injection-rate injection from continuing sluggishly after the end of the main injection, and the injection becomes more sharp.

Therefore, the injection rate mode is as shown in FIG.

Note that the above can also be applied to a hall type fuel injection valve.

The above case has the following effects.

(1) The amount of fuel during the ignition delay period can be reduced, and fuel noise can be reduced.

(2) It can prevent low-pressure, low-injection-rate injection from continuing sluggishly, reducing smoke emissions, fuel consumption, etc.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional fuel injection valve, Figure 2 is a sectional view showing a conventional fuel injection valve.
3 is a diagram showing the fuel injection rate of the fuel injection valve of FIG. 1, FIG. 3 is a sectional view showing a fuel injection valve of an embodiment of the present invention, and FIG. It is a diagram showing an injection rate. 3... Main needle valve, 8... Nozzle, 101... Main needle valve oil reservoir, 10... Check valve, 12... Throttle, 13...
...Secondary needle valve, 16...Secondary needle valve oil reservoir.

Claims (1)

[Claims] 1 The oil reservoir of the main needle valve into which fuel is introduced from the fuel injection pump, the nozzle that communicates the oil reservoir with the combustion chamber of the cylinder, and the valve seat provided inside the nozzle. In a fuel injection valve for an internal combustion engine, the fuel injection valve has a main needle valve that opens and closes a nozzle, and is slidably housed in a space around the main needle valve, and has an oil reservoir on one end and a spring on the other end. An oil passage branching from the fuel introduction passage to the oil sump of the main needle valve and leading to the oil sump of the auxiliary needle valve; A fuel characterized by comprising a check valve that energizes the needle valve, and a throttle that is arranged in parallel with the check valve and that gradually reduces the pressure in the oil reservoir of the auxiliary needle valve after the check valve is closed. injection valve.