JPS60204958A - Fuel injection unit of diesel engine - Google Patents

Abstract

PURPOSE:To improve the emission property and engine output due to the improvement of combustibility and reduce noises by controlling the pressure applied to a plunger member via a pressure control valve provided on a pressure passage communicated to the end surface of the plunger member. CONSTITUTION:A pressure control valve 21 controlling to reduce the pressure in a pressure passage 20 is arranged on the joint section of the pressure passage 20 communicated to the rear end surface of the plunger section 18b of a plunger member 18 and a communicating passage 28. A control unit 26 operating and controlling a solenoid drive circuit 25 to drive a pressure control valve 21 by receiving the outputs of rotation speed and load sensors 22, 23 is constituted. In the low-load, low-rotation region of an engine, a low-duty ratio signal is fed to the control valve 21 from a control unit 26, the fuel pressure is increased, the lift resistance force of a needle valve 16 is increased, atomization of the injected fuel is progressed via the lift suppression, and the emission performance is improved. In the high-load, high-rotation region, no lift suppression is applied, and the output is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection device that continuously supplies fuel to a diesel engine, and particularly relates to a fuel injection device that receives fuel pressure and refluxes it once and for all.
- This invention relates to an improvement in a fuel injection nozzle equipped with a bottle-type fuel injection nozzle in which the opening area of a fuel injection hole is changed in accordance with the lift deviation of a needle valve. In the present invention, the bottle-type fuel injection nozzle is used in a variety of ways, including a throttle-type fuel injection nozzle in which the throttle range in which the needle valve throttles the fuel injection hole is relatively wide among the lift speeds of the needle valve.

(Prior Art) Conventionally, as an example of a bottle-type fuel injection nozzle for this scale, as shown in Japanese Patent Application Laid-Open No. 57-151058, etc., a needle valve rear end side 1. : A slidable sylanger member is provided coaxially with the needle valve, and by applying a predetermined pressure to the plunger member, lift of the needle valve above a predetermined lift amount is suppressed, and the lift adjustment of the needle valve is reduced. This type is called a central plunger type, which allows the injected fuel to be atomized and the fuel injection rate to be changed by maintaining the throttle range in which the back needle valve restricts the fuel injection hole for a certain period of time. is known.

However, in this conventional device, the pressure of the fuel supplied from the fuel injection pump is directly applied to the plunger member, and when the needle valve is lifted within the throttle range of its lift range, the pressure of the fuel is uniformly applied to the plunger member. Because lift is suppressed, it is not possible to actively use functions that aim to atomize the fuel or change the fuel injection rate depending on the various operating conditions of the engine.
■It was difficult to improve mission performance and control switching within the output range.

In particular, there is a strong desire to achieve quiet drivability by reducing noise caused by diesel knock during steady driving, and it has also been difficult to address this issue by changing the fuel injection rate. .

(Objective of the Invention) The present invention has been made in view of the above points, and its object is to suppress the lift of the needle valve as described above.
By changing the pressure applied to the plunger member for the diesel engine, that is, the lift suppression of the needle valve, which is determined by the pressure applied to the plunger pflI, depending on the operating state of the engine, The object of the present invention is to change and control the characteristics of fuel injection into an engine by a fuel injection nozzle to characteristics intended to improve emission characteristics by improving combustibility, increase engine speed, and reduce noise during steady running.

(Structure of the Invention) In order to achieve the above object, the solution means of the present invention includes a bottle-type fuel injection nozzle that suppresses the lift of the needle valve by applying a predetermined pressure to the plunger member, as described above. In a diesel engine fuel injection device, a pressure control valve is provided in a pressure passage that communicates with an end face of a plunger member of a fuel injection nozzle and applies pressure, and acts on the blanking member as at least one of engine speed and load increases. As well as reducing the pressure,
A control device is provided to drive the pressure control valve 1j to relatively increase the pressure acting on the plunger member in the vicinity of the steady running region. This makes good use of the lift characteristics of the needle valve in the bottle-type fuel injection nozzle to variably control the lift suppression start timing and suppression state depending on the engine operating conditions, including the steady running range. be.

(Effects of the Invention) Therefore, according to the present invention, the lift of the needle valve is controlled by controlling the pressure applied to the plan seat member that suppresses the lift of the needle valve in the bottle-type fuel injection nozzle used in a diesel engine. The suppression start timing and suppression state are variably controlled according to the engine operating condition,
As at least one of the engine speed d3 and the load increases, the pressure acting on the plunger member is lowered to improve the injection rate and engine output. By increasing the pressure acting on the member and reducing the injection gFI rate, it is possible to improve the emission performance and satisfy the output, J, and 1 transmission performance, while at the same time reducing the Ff force acting on the plunger member near the steady running region. By increasing the fuel injection rate and improving the injection rate, diesel knock can be suppressed and noise can be reduced to I, resulting in a quiet ride comfort level of 11.

(Example) Hereinafter, an example of the present invention will be described in detail based on FIG.

FIG. 1 shows the combustion section of a direct l171i type diesel engine according to an embodiment of the present invention; 11. ! A cylinder block 3 having a cylinder 2, a cylinder head joined to the upper surface of the cylinder block 1, 4 a piston fitted in the cylinder 2 so as to be movable back and forth; A cavity 4a for forming a combustion chamber 5 is recessed in the top surface.

On the other hand, although not shown, the cylinder head 3 includes an intake port that supplies intake air to the combustion chamber 5, and an intake port that supplies intake air to the combustion chamber 5.
Due to the arrangement shape of the intake port, the intake air drawn into the combustion chamber 5 during the intake stroke of the engine generates a swirl within the combustion chamber 5. is configured to occur.

Further, the cylinder head 3 is equipped with a glow plug 6 that heats the inside of the combustion chamber 5 when the engine is started, and a bottle-type fuel injection nozzle 7 that injects fuel into the combustion chamber 5. The fuel injection direction of the nozzle 7 is set along the intake swirl.

As shown in FIG. 2, the bottle-type fuel injection nozzle 7 has a fuel injection hole 8 facing the combustion chamber 5 on the tip side (lower side in the figure).
is provided with a nozzle body 10 in which a fuel inlet 9 connected to a fuel injection pump (not shown) opens at the rear end side (upper side), and there are nozzle bodies 10 inside the nozzle body 10 from the rear end side to the front end side. In this order: spring chamber 12, needle valve support hole 1
3 and a fuel pressure chamber 14 are formed, and these cavities are provided coaxially with the fuel injection hole 8 and in communication with the fuel injection hole 8. In addition, the above-mentioned fuel fathom 9 and fuel pressure chamber 1
4 (fuel nozzle hole 8) through a fuel passage 15 formed in the nozzle main (4, 10).Furthermore, a needle valve 16 is provided in the cavity from the spring chamber 12 to the fuel r1 nozzle hole 8. The needle valve 16 is fluid-tightly supported in the valve support hole 13 and fitted so as to be openable.
The pressure receiving part 16b receives the fuel pressure in the fuel pressure chamber 14.
, a valve portion 16C for opening and closing the fuel injection hole 8, and a throttle portion 16d disposed within the fuel injection hole 8,
A certain gap is formed between the throttle portion 16d and the wall surface of the fuel injection hole 8.

In addition, a nozzle spring 17/)ζ for urging the needle valve 16 in the closing direction /'j is installed in the spring chamber 12, and the high 11 fuel from the fuel injection pump is supplied from the fuel inlet 9. The fuel in fi force v14 passes through the fuel passage 15.
When the fuel pressure is applied to the pressure receiving part 16b of the needle valve 16, the needle valve 16 is opened against the urging force of the nozzle spring 17, and the fuel passes through the fuel nozzle hole 8 to the engine. is injected into the combustion chamber 5, and at that time, the gap between the throttle portion 16d and the wall of the fuel injection hole 8 changes depending on the needle valve 16 glue 71 to The opening area of the fuel injection hole 8 is configured to change.

As shown in FIG. 3, the relationship between the lift amount and the opening area of the needle valve 16 is as shown in FIG. , the throttle section 16d enters a throttle range in which the opening area of the fuel nozzle hole 8 is kept substantially constant by the throttle of the fuel nozzle hole 8, and then, as the throttle section 16d escapes from the fuel nozzle hole 8, Needle valve 16 glue 7
After shifting to a proportional change range in which the opening area of the fuel nozzle hole 8 increases in proportion to 1 to -, it is lifted to the full lift position.

In addition, in FIG. 2, 19 is a fuel discharge passage,
A mechanism (b) for leaking fuel leaked from the fuel pressure chamber 14 into the spring chamber 12 through the minute gap between the needle valve 16 and the needle valve support hole 13 to the fuel Fl tank (not shown) outside the nozzle. be.

Furthermore, a cylinder 11 that communicates with the spring chamber 12 is formed coaxially with the needle valve 16 in the nozzle body 10 on the rear side of the spring narrowing 12, and the cylinder 11 is connected to the outside of the nozzle body 10 through the pressure passage 20. , the pressure is 8'f with fuel as the pressure medium! (not shown). Further, a plunger member 18 that coincides with the axis of the needle valve 16 is slidably fitted in a cavity extending from the F cylinder 11 to the spring chamber 12. The plunger member 18 has a rod portion 18a disposed within the spring toe 12, a blank portion 18b fitted within the cylinder tacho, and an eye between the plunger rod 18a and the plunge P portion 18b. ``Device Riru Tsuba FJi 18 G and 7
2 days, the flange 18G is movable in a stroke range from the rear end wall of the spring chamber 12 to the spring 12 intermediate part (17) until it comes into contact with the stopper member 27, and the above-mentioned Stopper member 27 of flange 18c
In a state where the movement of the plunger member 18 toward the needle valve 16 side is restricted by contact with the IJ, the Rondo gA18
The tip of the plunger member 18, that is, the tip of the plunger member 18, is positioned so as to face the spring receiving portion 16a, which is the rear end of the needle valve 16, with a predetermined gap therebetween. As a result, the needle valve 16 lifts and its spring receiving portion 16
a is in contact with the tip of the rod portion 18a of the plunger member 18, a predetermined pressure acting on the rear end of the plunger portion 18b of the plunger member 18 causes the needle valve 1 to close.
It is configured such that the lift amount of No. 6 is suppressed.

Further, the plunger portion 181 of the plunger member 18
! In the pressure passage 20 that communicates with the other end, the fuel discharge passage 19 is connected to the outer part of the nozzle body 10 via the communication passage 28, and the pressure passage 20 is connected to the communication passage 28 at the part of the pressure passage 20 that To explain a series control system in which a pressure control valve 21 consisting of a duty valve is disposed and controls the operation of the pressure control valve 21 to reduce the pressure within the engine, 22 controls the engine rotation speed. Rotational speed sensor 9.231J for detecting the load condition of the engine.
22.Receive the output of 23, ff/7illIll*II
Activates the solenoid drive circuit 25 for driving the duty solenoid 1: of the valve 21. Control 1, 1IIt1
The circuit II, II control path 24 and solenoid drive circuit 25 constitute a control device 26 that controls the operation of the control valve 21 according to the operating state of the engine.

For example, as shown in FIG. 4, when the engine is in a low phase load state and a low rotation state, the control device 26 sends a low duty ratio signal to the pressure f, I+ control valve 21, and applies fuel to the plunger 8IHJ181. Increase FlrI power,
When the carrot is in a high load state and a high rotation state in full load F/L, a high duty ratio signal is sent to the pressure III control valve 21 to lower the fuel pressure applied to the plunger part '4A18. , the pressure acting on the plunger member 18 is controlled to be reduced as at least one of the engine speed and the load increases, and the steady running region 11i!, that is, 0-droad R/l is controlled.
- Control mTJ to relatively increase the pressure acting on the plunger member 18 and lower the injection rate by setting the duty ratio of the duty ratio signal relatively lower than the change characteristics of other regions in the vicinity. It is.

Note that the pressure passage 20 may be covered so that the fuel supplied to the fuel inlet 9 is branched and supplied, or may be supplied with pressure from a separate pressure source, and in the former case, the fuel pump discharge pressure It is preferable to interpose a check valve between the lifting platform (J) using a lifting platform (J) so that the pressure of the pressure passage 20 does not act on the combustion shelf inlet 91J.

Next, the operation of the above embodiment will be explained. Basically, when high-pressure fuel is fed under pressure from the fuel pump to the J nozzle 7, the high-pressure fuel is transferred from the fuel inlet 9 to the fuel passage. 15 into the fuel pressure chamber 14, and the fuel Fl
The pressure receiving part 16b of the needle valve 16 is pressed in the pressure seedling 14, and the needle valve 16 is moved by the pressure receiving part 16b of the nozzle spring 17. j
The valve is opened by lifting it against the pressure, and the fuel r1 in the fuel pressure chamber 14 is turned off by the tin valve of the needle valve 16.
It is injected and supplied to the combustion chamber 5 of the engine through the 1FI injection hole 8. Then, as the fuel pressure introduced into the fuel pressure chamber 14 increases, the lift force of the needle valve 16 increases, and the spring receiving part 16a of A comes into contact with the plunger ↑ member 18.
From then on, the needle valve 16 t, t is integrated with the sinker member 18 and becomes removable.

In addition, the combustion was carried out from the pressure source through the pressure passage 20 to the cylinder 11 of the nozzle 7? 1. ? il pressure (acting on the rear end surface of the 19222 part 441 F3 in the cylinder 11 to move the plunger ζ member 18 to the second position F16
Press until this plunger 81 ((I)
By applying pressure to B, the lift operation of the needle valve 16 after the spring receiving portion 16a abuts against the plan seat member 18 is controlled.

The control for this needle valve 16 will be explained along the control 70-CH1-1- shown in FIG. In step S2, the load signals from the load sensors 23 are respectively input to the control filter device 26, and then in step S3, the duty ratio corresponding to the operating state of the engine is stored in advance based on the rotation speed signal and the load signal. Then, in step S4, the duty solenoid of the pressure control valve 21 is driven according to the read duty ratio map, and the fuel pressure applied to the plunger member 18 by the pressure control valve 21 is adjusted. Controlled and disciplined above step S1
Return to step S2. S3 is repeated.

As a result, when the engine is in a low-load, low-speed region, a low duty ratio signal is sent from the control unit AF 26 to the pressure control valve 21, thereby increasing the fuel pressure applied to the plunger member 18. As a result, the lift resistance force of the needle valve 16 by the plunger member 18 increases, and due to this increase in the lift resistance force of the plunger member 18, the needle valve 16 moves to the throttle portion 16d after its spring receiving portion 16a abuts the plunger member 18. The lift is suppressed when the fuel injection hole 8 is in the throttle range where the fuel injection hole 8 is throttled, and by suppressing the lift of the needle valve 16 in this throttle range, fuel is injected from the fuel injection hole 8 at high speed. This state is maintained for a long time, promoting atomization of fuel injection, improving the ignitability and combustibility of the fuel, reducing HC emissions, and improving emission performance.

On the other hand, when the engine is in a high-load, high-speed region, a high duty ratio signal is sent from the control device 26 to the pressure control valve 21, so that the fuel pressure applied to the plunger member 18 is lowered, and the fuel pressure applied to the plunger member 18 is reduced. The lift resistance of the needle valve 16 is reduced, and this reduction in the lift resistance of the plunger member 18 causes the needle valve 16 to move toward its throat 1-16. d is smoothly moved 71- without being subjected to lift suppression until it reaches the lift position in the proportional change range on the way to escape from the fuel nozzle hole 8 or the full lift position after the throttle part 16d completes escape, As a result, fuel injection into the engine (71hX
m is maintained, and the engine output can be improved.

Roughly speaking, the engine is close to the steady operating range, that is, the adjustment i*
When the load is in the R/L state where t is not changed, the duty ratio is set to f+I'l, which is relatively lower than changes in the duty ratio due to changes in engine speed and load in other regions, and this Duty ratio signal is controlled
By being sent from the 1'D device 26 to the pressure control valve 21, the fuel pressure applied to the plunger portion 018 becomes relatively high and the plunge! - Needle valve by member 18] The lift resistance force of the member 18 increases, and as the fuel injection rate decreases, the occurrence of deep pill knock is suppressed, thereby achieving low noise.

Note that the present invention is not limited to the above embodiments,
It also includes various modifications, and in the above embodiment, I
J. Is the fuel pressure applied to the plunger member 18 of the fuel injection nozzle 7 controlled based on the engine speed and load to avoid changing the lift suppression start of the needle valve 16? intake 711
ayoshi, cold 7Jl water temperature IQ, J, or atmosphere F0 is detected and engine white smoke light and 1 operating state <t of intake air in the combustion chamber
1i+ii The state of low heat 1B) is determined, and when the engine is running with white smoke, the pressure applied to the plunger member 18 is increased to improve the combustibility of the fuel8.
T! The white smoke 'f19 may also be eliminated.

In addition, when the supercharger is applied to the Tigel engine and the intake supercharging pressure is 11 (when it is
By increasing the pressure applied to the shrine 18 to a high pressure, the distribution of the fuel r1 to the intake air before combustion is improved, and the C combustion t is made good, and when the supercharging pressure of the intake air is high, the IJ silansha member 18 By lowering the pressure applied to the fuel injection ω
It is also possible to improve engine output by ensuring that

Furthermore, when the exhaust recirculation rate is large, the FF force applied to the plunger member 18 can be applied to a diesel engine equipped with an exhaust recirculation system to prevent the deterioration of smoke (black smoke). can.

Furthermore, in the configuration of the above embodiment, a swirl control till device that controls the strength of the intake swirl generated in the combustion chamber of the engine can be added to simultaneously control the plunger pressure and the swirl according to the operating state of the engine. This may improve the engine's emission performance in the low load range, reduce smoke generation in the low speed range, and improve the output direction of the series.

It goes without saying that the present invention can be applied not only to the direct injection type diesel engine as in the above embodiment, but also to other types of diesel engines such as the swirl chamber type diesel engine.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of essential parts of a diesel engine according to an embodiment of the present invention, Fig. 2 is an overall configuration diagram of a fuel injection device showing a fuel injection nozzle in longitudinal cross-section, and Fig. 3 is a needle in the fuel injection nozzle. Figure 4 is a characteristic diagram showing the relationship between valve lift and fuel nozzle opening volume. Figure 4 shows the engine operating conditions and pressure.
An explanatory diagram of the relationship with the duty ratio signal output to the valve,
FIG. 5 is a flowchart diagram of the control system. 5... Combustion chamber 7... Combustion filter (g)
Nozzle 8...Fuel injection hole 9...Fuel 4
Person F-110...Nozzle body 11...
・Schilling 14...Fuel pressure chamber 15...
...Fuel 1 passage 16...2-dollar valve 16c...
...Valve part 16d...Throttle part 17...Nozzle spring 18...Plunge ↑□FJ (JJ 18a...
...[]Turado 18i)...Brange section 20...Pressure passage 21...FF force control valve 22...r rotation #, t ? Nυ23...
...Load sensor 24...S I11 circuit 25
... Solenoid drive circuit 26 ... Control device @ 1 Fig. 2 a83 Fig. 5

Claims (1)

[Claims] (1) Aligns with the axis of the needle valve, and one end is the needle
A sylanger member is provided facing the plunger valve and is slidable in its axial direction, and a predetermined pressure is applied to the other end face of the plunger member to suppress the rift of the needle valve at a predetermined pressure. In the fuel injection device for a diesel engine having a bottle-type fuel injection nozzle, a pressure control valve is installed in a pressure passage communicating with the other end surface of the plunger member of the bottle-type fuel injection nozzle, and the engine rotation speed and As at least one of the zero loads increases, the pressure acting on the plunge P member is lowered, and the pressure control valve is actuated to relatively increase the pressure acting on the plunger member in the vicinity of the steady running region. A fuel injection display for a diesel engine characterized by the provision of an oll H position.