JPS61129459A - Fuel injector for diesel engine - Google Patents

Abstract

PURPOSE:To reduce the idle vibration by installing a lift-amount control mechanism which is controlled according to the engine operation state and forms the throttle range in which a needle valve throttles an injection hole is formed by suppressing the lift amount of a needle valve. CONSTITUTION:When the fuel introduced from a fuel introducing port 3 acts onto the pressure receiving part 10b of a needle valve 10 fitted in slidable ways onto a nozzle body 4 from a fuel passage 9, and lift-shifts the pressure receiving part, a fuel injection nozzle 1 jets-out fuel from an injection hole 2 opened at the same time. In this case, a left-amount control mechanism 15 for suppressing the lift amount of the needle valve 10 by adjusting the pressure acting onto the terminal edge surface of the plunger part 12b of a plunger member 12 installed coaxially with the needle valve 10 is installed. In other words, the leak through the leak passage 18 of a cylinder 5 is varied by opening/closing-controlling a pressure control valve 19 by a control means 24 on the basis of the engine operation state, and the pressure acting onto the plunger member 12 is varied.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel injection device for injecting and supplying fuel to a diesel engine. The purpose of this invention is to improve a fuel injection device equipped with a throttle-type fuel injection nozzle.

(Conventional technique #i) Conventionally, as a fuel injection device for a diesel engine,
For example, as disclosed in Japanese Unexamined Patent Publication No. 57-151058, lift of the needle valve above a predetermined lift amount is suppressed, and the needle valve throttles the fuel injection hole within the lift range of the needle valve. There is a known technology that aims to atomize the injected fuel in a low load range by using a pre-lift that maintains the throttle range in a constant state for a certain period of time.

However, in this conventional device, when the needle valve is lifted into the throttle area of its lift range,
-Idle vibration may become large during idle link because lift is suppressed regularly.

That is, during idle link, since the load is low, the lift amount of the needle valve is in the throttle range, and the nozzle hole is narrowed and narrowed. In this state, for example, if carbon generated in the combustion chamber of the engine becomes clogged between the tip of the needle valve and the injection hole, the opening area changes and the injection period becomes longer.
A difference in injection period occurs between each cylinder, and idle vibration occurs based on this difference. Furthermore, the opening area of the throttle region changes due to manufacturing errors in the fuel injection nozzle, resulting in errors in the injection period between cylinders. As described above, in the throttle region, the nozzle holes are narrowed and the opening area is narrow, so even the slightest fluctuation in area as described above increases the difference in injection period, causing idle vibration.

(Object of the Invention) In view of the above circumstances, the present invention provides a fuel injection device for a diesel engine that reduces idle WliIJ during idling without inhibiting atomization due to lift suppression in a low load range. The purpose is to

(Structure of the Invention) The fuel injection device of the present invention has a lift amount control mechanism that suppresses the lift amount of the needle valve to form a throttle region in which the needle valve narrows the injection hole. The invention is characterized by comprising a control means for controlling the lift to be above the throttle range during idling, suppressing the lift to the throttle range during low load ranges other than idling, and controlling the lift to above the throttle range during high load ranges. It is something to do.

(Effects of the Invention) According to the present invention, by increasing the opening area by increasing the lift amount beyond the throttle range during idling, carbon may adhere to the nozzle tip or fluctuations in the nozzle opening area due to manufacturing errors can be avoided. Even if there is, the fluctuation in the injection period due to this becomes small, and the difference in the injection period between cylinders also becomes small, making it possible to reduce the occurrence of idle vibration.

In addition, in low load ranges other than the idling range, the lift amount is suppressed to the throttle range to narrow the opening area and atomize the fuel to improve combustibility, while in high load ranges, the lift amount is reduced to the throttle range. It is possible to lift the fuel injection hole more widely to increase the opening area, secure the required fuel injection amount, and improve the output.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

Example 1 Figure 1 shows a vertical cross-sectional view of the fuel injection nozzle in this example, Figure 2 shows the relationship between the lift amount of the needle valve, the opening area, and the valve opening pressure, and Figure 3 shows the relationship between the lift amount of the needle valve, the opening area, and the valve opening pressure. FIG. 3 is an explanatory diagram showing the relationship between states and control areas.

The throttle type fuel injection nozzle 1 is for a direct injection type diesel engine, and has a nozzle hole 2 facing the combustion chamber at the tip side (lower side in the figure) and a fuel injection pump (not shown) at the rear side. The connected fuel inlet 3 leaks through the open nozzle body 4, and inside the nozzle body 4, from the rear end side to the front end side, there is a cylinder 5, a spring chamber 6, a needle valve support hole 7, and a fuel pressure. A chamber 8 is formed, and these cavities are provided coaxially with the nozzle hole 2 and in communication with each other. In addition, the fuel inlet port 3 and the fuel pressure chamber 8
The nozzle hole 2 is in communication with the fuel passage 9 formed in the nozzle body 4, and the fuel inlet 3 and the cylinder 5 are in direct communication with each other.

Furthermore, a needle valve 10 is slidably inserted into the needle valve support hole 7 in a fluid-tight manner in the cavity between the spring chamber 6 and the injection hole 2. A spring receiving part 10a arranged therein, a pressure receiving part 10b receiving the fuel pressure in the fuel pressure chamber 8, a valve part 10c opening and closing the nozzle hole 2, and a throttle part 10 (I) arranged in the nozzle hole 2. A certain minute gap is formed between the throttle part 10d and the wall surface of the nozzle hole 2.

Further, a nozzle spring 11 is installed in the spring palm 6 to urge the needle valve 10 in the closing direction, and high-pressure fuel from the fuel injection pump passes through the fuel passage 9 from the fuel inlet 3 to the fuel. When introduced into the pressure chamber 8, the needle valve 10 is opened against the urging force of the nozzle spring 11 due to the action of this fuel pressure on the pressure receiving part 10b of the needle valve 10, and the fuel passes through the injection hole 2. The amount of lift of the needle valve 10 and the opening area of the nozzle hole 2 change as the gap between the throttle portion 10d and the wall of the nozzle hole 2 changes depending on the lift amount of the needle valve 10. is configured to do so.

That is, as shown in FIG. 2A, the relationship between the lift amount and the opening area of the needle valve 1o is such that the initial opening area increases as the valve part 10c opens.
d is located inside the nozzle hole 2 and enters the throttle region where the opening area of the nozzle hole 2 is kept approximately constant by the throttle of the throttle section 10d, and then the throttle section 10d escapes from the nozzle hole 2 and its The tip tapered portion lifts the nozzle hole 2 to the full lift position when the opening area of the nozzle hole 2 increases in proportion to the lift amount of the needle valve 10 when the needle valve 10 moves to a proportional change region.

Furthermore, a plunger member 12, which is aligned with the axis of the needle valve 10, is fitted into the cavity extending from the cylinder 5 to the spring chamber 6 on the spring chamber 6@ side so as to be freely movable. The plunger member 12 includes a rod portion 12a disposed within the spring chamber 6, a plunger portion 12b fitted within the cylinder 5, and a flange portion located between the rod portion 12a and the plunger portion 12b. 12G, and is movable over a stroke range until the flange 12G contacts the rear end wall of the spring chamber 6 and a stopper member 14 disposed at an intermediate portion of the spring chamber 6. When the movement of the plunger member 12 toward the needle valve 10 is restricted by the abutment of the collar portion 12C against the stopper member 14, the tip of the rod portion 12a abuts against the spring receiving portion 10a of the needle valve 10. There is.

And the plunger portion 12b of the plunger member 12
A lift amount control mechanism 15 is provided that suppresses the lift amount of the needle valve 10 by adjusting the pressure acting on the rear end surface. That is, a piston 16 is interposed in the cylinder 5 in which the plunger portion 12b of the plunger member 12 vibrates, and the cylinder 5 below the piston 16 has a first leak passage 17 and above this a second leak passage. 18 have connection openings, respectively, and the second leak passages 18
A pressure control valve 19 consisting of an on-off valve is interposed therein.

The piston 16 is held in place by engaging with a protrusion 5a on the inner surface of the cylinder 5, and is restricted within a predetermined range of movement.

The operation of the pressure control valve 19 of the lift amount control titFR mechanism 15 is controlled by a signal from a rotation speed sensor 2o that detects the engine rotation speed and a load sensor 21 (control lever opening sensor of the fuel injection pump) that detects the engine load state. The engine is controlled in accordance with a control signal outputted from the control means 24 according to the operating state of the engine. According to the opening/closing operation of the pressure control valve 19, the leak through the second leak passage 18 of the cylinder 5 is changed, and the pressure of the cylinder 5, that is, the pressure directly acting on the plunger member 12 is changed. It is something. This control means 24 includes an arithmetic circuit 2 that calculates the operating state based on the engine speed and load and calculates the opening/closing state of one pressure υ control valve accordingly.
2, and a drive circuit 23 that outputs a control signal according to the output of the arithmetic circuit 22.

The control by the control means 24 is performed according to the characteristics as shown in FIG. It is divided into a third area (■) which is a high load area, and one pressure control valve is opened in area (1) and (2).
The pressure control valve 19 is controlled to close in the region ■,
Needle valve 10 according to these areas I, II, I [I
This is to change the lift suppression state of.

In the above area, when idling, pressure control valve 1
9 is controlled in the open state, and the plunger member 12 has the openings of the first and second leak passages 17 and 18 in the plunger portion 1.
It lifts without being subjected to lift suppression until it is closed by 2b, and after this is closed, it is subjected to lift suppression due to the fuel pressure accompanying the movement of the piston 16. In addition, in region (2), that is, in a low load region excluding idling, the pressure control valve 19 is closed, and the opening of the first leak passage 17 is closed by the plunger portion 12b of the plunger member 12 against the lift of the needle valve 1o. Since the pressure control valve 19 remains closed from the time when the opening of the first leak passage 17 is closed, the plunger member 12 suppresses the lift by the fuel pressure acting on the upper surface of the piston 16. Therefore, the suppression range is wider than the above-mentioned area technique. Furthermore, in the area (3), the pressure control valve 19 is opened similarly to the area work, and the plunger member 12 is subjected to lift suppression until the openings of the first J5 and the second leak passage 1-7.18 are closed by the plunger portion 12b. After the piston 16 is closed, the lift is suppressed by the fuel pressure caused by the movement of the piston 16.

That is, in response to the opening and closing of the pressure control valve 19 as described above, the relationship between the valve opening pressure (fuel pressure) acting on the pressure receiving part 10b of the needle valve 1o and the lift of the needle valve 1o is determined by the second
As shown in Figure B, the area ■ where the pressure control valve 19 is closed
As shown by the solid line PL, lift suppression acts on the lift amount in the throttle range, fuel is injected from the nozzle hole 2 at high speed with the opening area narrowed, and atomization of the fuel injection is promoted. Improves ignitability and combustibility.

In addition, in @area work and ■, where the pressure control valve 19 is open, as shown by the broken line P2, lift suppression acts in the lift amount above the throttle range, and the fuel is Injection takes place. Therefore,
When the nozzle is idling, even if there are variations in the opening area due to carbon adhesion to the nozzle or manufacturing errors, the increased opening area reduces the difference in injection period and reduces idle vibration. Further, in the high load region (region ①), it is possible to secure the fuel injection amount, which is increasing in demand, and improve the engine output.

Embodiment 2 This embodiment shows an example of another throttle type fuel injection nozzle 7' as shown in FIG. 10, lift suppression is performed variably.

That is, for the needle valve 10 formed to have the same lift characteristics as in the previous example (see FIG. 2A), the plunger member 12
is positioned with a predetermined gap d maintained between it and the spring receiving portion 10a of the needle valve 10. Thus, in a state where the needle valve 10 is lifted and its spring receiving portion 10a is in contact with the tip of the rod portion 12a of the plunger member 12, the plunger portion 12b of the plunger member 12
A lift control fl1 mechanism 25 is provided so that the lift amount of the needle valve 10 is suppressed by a predetermined pressure acting on the tip end surface.
is configured.

The cylinder 5 into which the plunger portion 12b of the plunger member 12 is inserted is connected to the nozzle body 4 via a pressure passage 26.
Fuel pressure is supplied from an external pressure source (not shown). This pressure passage 26 is connected to a fuel discharge passage 28 via a communication M27 (), and a pressure control valve comprising a duty valve for controlling the pressure of the pressure passage 14 is provided at the connection part of the pressure passage 26 with the communication passage 27. A valve 29 is provided.

To explain the control system that operates this pressure control valve 29, the rotation speed sensor 20 and load sensor 2 similar to those described above will be described.
The arithmetic circuit 30 receiving the output No. 1 controls the operation of a solenoid drive circuit 31 for driving the duty solenoid of the pressure control valve 29, and thereby controls the operation of the pressure control valve 29 according to the operating state of the engine. A control means 32 for controlling the operation of the lift amount control mechanism 25 is configured.

For example, as shown in FIG. 5, the control means 32 sends a low duty ratio signal to the pressure control valve 29 to increase the fuel pressure applied to the plunger member 12 when the engine is in a low load state other than when idling. When the engine is in a high load state approaching full load F/L and in the idling range 1/D, a high duty ratio signal is sent to the pressure control valve 29 to lower the fuel pressure applied to the plunger member 12. It is intended to be controlled.

Other components having the same structure as those of the example shown in FIG.

Note that the pressure passage 26 may be supplied with the fuel supplied to the fuel inlet 3 in a branched manner, or may be supplied with pressure from a separate pressure source.

Next, to explain the operation of the above embodiment, the needle valve 10 lifts in accordance with the fuel pressure, fuel injection is started, the lift of the needle valve 10 increases due to the increase in fuel pressure, and the spring receiving portion 10a of the needle valve 10 increases. is the plunger member 12
When they come into contact with each other, they lift as one.

Further, the fuel pressure introduced from the pressure source into the cylinder 5 through the pressure passage 26 acts on the rear end surface of the plunger member 12 to press the plunger member 12 toward the needle valve 10 side, and the plunger portion 12b of this plunger member 12 The lift operation of the needle valve 10 is controlled by applying pressure to the needle valve 10 .

The lift control of the needle valve 10 will be explained according to the control flowchart shown in FIG. is input. Thereafter, in step S3, a duty ratio corresponding to the operating state of the engine is read from a duty ratio map stored in advance based on the control characteristics shown in FIG. 5, based on the rotation speed signal and load signal, and step In S4, the duty solenoid of the pressure control valve 29 is driven according to the duty ratio read in step S3, and the two pressure control valves drive the plunger member 12.
The fuel pressure applied to is controlled. If this occurs, the process returns to step S1 and the subsequent steps are repeated.

As a result, when the load is in a low load range except during idle linking, a low duty ratio signal is sent from the control means 32 to the pressure control valve 29, so that the 15291 member 12
As the fuel pressure applied to the needle valve 10 increases, the lift resistance of the needle valve 10 by the plunger member 12 increases, and the needle valve 10 suppresses lift when the throttle portion 10d is in the throttle region where the nozzle hole 2 is throttled. By suppressing the lift in this throttle range, atomization of the injected fuel is promoted. Furthermore, when the engine is in a high-load, high-speed region, a high duty ratio signal is sent from the control means 23 to the two pressure control valves, so that the fuel pressure applied to the plunger member 12 is reduced and the needle valve 10 is The lift resistance force is reduced, and the needle valve 10 smoothly moves without being subjected to lift suppression until the throttle portion 10d reaches the lift position in the proportional change range on the way to escape from the nozzle hole 2, or the full lift position when the escape is completed. As a result, the amount of fuel injected into the engine can be secured and the engine output can be improved.

Further, during idling, a high duty ratio signal is sent from the control means 32 to the pressure control valve 29, so that the fuel pressure applied to the plunger member 12 becomes lower than the above-mentioned low load region, and the needle valve 10 is activated by the throttle valve 29. Even if the aperture area is lifted more than the area and there are variations in the opening area due to carbon adhesion to the nozzle or manufacturing errors,
Due to the increased opening area, the difference in injection time becomes smaller and idle vibration is reduced.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a fuel injection device showing a longitudinal section of a fuel injection nozzle according to a first embodiment of the present invention, and FIGS. 3 is an explanatory diagram showing the relationship between the engine operating state and the control area in FIG. 1, and FIG. 4 is a characteristic diagram showing the relationship between the nozzle opening area and valve opening pressure. FIG. 5 is an explanatory diagram showing the relationship between the operating state of the engine and the duty ratio signal output to the pressure control valve in FIG. 4; The figure is a flowchart diagram of the control means in Fig. 4. 1.1'... Fuel injection nozzle 2... Nozzle hole 3... Fuel inlet port 4... ...Nozzle body 5...
・Silonada 10...Needle valve 10b
......Pressure receiving part 10d...Throttle part 12...Plunger member 15.25...Lift amount control structure 17.18.
...Leak passage 19.29...Pressure control valve 20...Rotation speed sensor 21...Load sensor 22.30...Arithmetic circuit 23 .31...Drive circuit 24.32...Control means 26...Pressure passage Figure 1 Figure 4 Procedure correction method) % formula % 2. Name of the invention Diesel Engine fuel injection system 3, relationship with the case of the person making the amendment Patent applicant address: 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Name:
Mazda Corporation 4, Agent: 5-2-1 Roppongi, Minato-ku, Tokyo, Uraiya Building, 7th Floor (731g> Patent Attorney Yanagi 1) Masashi (1 idiot) 5
, date of amendment order

Claims (1)

[Claims] (1) For a throttle type fuel injection nozzle where the tip of the needle valve goes in and out of the nozzle hole, a lift amount control mechanism is provided to suppress the lift amount of the needle valve and form a throttle area where the needle valve narrows the nozzle hole. , according to signals corresponding to the engine speed and load, the lift amount is lifted above the throttle range during idling, the lift amount is suppressed to the throttle range during low load ranges other than idling, and the lift amount is reduced during high load ranges. A fuel injection device for a diesel engine, comprising a control means for operating the lift amount control mechanism so as to lift the lift above a throttle range.