JPS60204959A - Fuel injection unit of diesel engine - Google Patents

Abstract

PURPOSE:To improve combustibility by reducing the pressure as one of the engine rotation speed and load is increased and further reducing the pressure in the high-load region when the atmospheric pressure is reduced via a pressure control valve provided on a pressure passage communicated to the end surface of a plunger member. CONSTITUTION:The duty ratio together with signals from rotation speed, load, and atmospheric pressure sensors 22-24 are fed to a control unit 29, and at a lowland, the duty solenoid of a pressure control valve 21 is driven in response to the duty ratio, and the fuel pressure applied to a plunger member 18 is con trolled by the valve 21. At a highland, the duty ratio is corrected under the high load, the duty solenoid of the valve 21 is driven, and under the low load and low rotation, a low-duty ratio signal is fed to the valve 21, the fuel pressure applied to the member 18 is increased, the lift of a needle valve 16 is suppressed, an injection nozzle 8 is squeezed, and atomization of the injected fuel is progressed. Under the high load and high rotation, the lift suppression of the valve 16 is small, and the fuel injection quantity can be secured.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a diesel engine kT fuel v1 with #+ DI
(Regarding the fuel injection device that feeds Jl, in particular, the pintle air-fuel This opens the door to the improvement of devices equipped with an injection nozzle.In addition, in the present invention, the 91 Bintle type fuel injection Of nozzle is a fuel injection nozzle equipped with a fuel injection nozzle. The 1J to 1111 range is used in various ways, including relatively wide throttle types.

(Prior Art) Conventionally, as an example of this type of bottle-type fuel injection nozzle, as disclosed in Japanese Patent Application Laid-Open No. 57-151058, etc., a needle valve is provided on the rear end side of the needle valve coaxially with the needle valve. A slidable plunger member is provided on the plunger member, and by applying a predetermined pressure to the plunger member, the lift of the needle valve at a predetermined lift of 1 or more is suppressed, and the needle valve reaches the fuel injection hole within the lift range of the needle valve. By maintaining the throttle range in a closed state for a certain period of time,
A so-called central plunger type is known in which it is possible to atomize the injected fuel, change the fuel injection rate, etc.

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 supplied from the fuel injection pump is applied to the plunger member. Since the lift is suppressed at the same time, 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 control performance improvement, output change, etc.

In particular, it is strongly desired to reduce the occurrence of smoke caused by a decrease in combustibility in the high load range when driving at high altitudes (when atmospheric pressure drops), and this can be addressed by changing the fuel injection rate mentioned above. It was also difficult.

(Object of the Invention) The present invention has been made in view of the above points, and its object is to reduce the pressure applied to the plunger member for suppressing the lift of the needle valve (i.e., to reduce the pressure applied to the plunger member). By changing the lift suppression of the needle valve, which is determined by the applied pressure of The objective is to improve the engine output, and to change the characteristics to reduce smoke in the high load range when the atmospheric IF is lowered.

(Structure of the Invention) In order to achieve the above object, the solution of the present invention is to provide a bottle-type fuel injection nozzle that suppresses the lift of the needle valve by applying a predetermined pressure to the plunger member. In the fuel injection device for a diesel engine, 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,
The pressure control valve is actuated to reduce the pressure acting on the plunger member as at least one of engine speed and load increases, and to further reduce the pressure acting on the plunger member in the 8 load range when atmospheric pressure drops. It is equipped with a control device to

As a result, by making good use of the lift characteristics of the needle valve in the bottle-type fuel injection nozzle, the lift suppression t111 start timing and suppression υ1 state can be varied according to the operating conditions of the engine, including the high-altitude, high-load region. It was designed to be controlled.

(Effects of the Invention) Therefore, according to the present invention, in a bottle-type fuel injection nozzle used in a diesel engine, the lift of the needle valve is suppressed by controlling the pressure applied to the plunger member that suppresses the lift of the needle valve. The start timing and suppression state are variably controlled according to the operating state of the engine, and as at least one of the engine speed and load increases, the pressure acting on the plunger member is reduced to improve the injection rate and improve engine output. At the same time, when the J-engine rotation speed and load are low, the pressure acting on the blanking member is increased to reduce the injection rate and improve emissions performance. In high-load areas at high altitudes where fuel pressure has decreased, the pressure acting on the plunger member is reduced to increase the injection rate and increase the premixing of the injected fuel and air, improving combustibility and suppressing smoke generation. It is something.

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

FIG. 1 shows the combustion arm of a direct injection diesel engine according to an embodiment of the present invention, in which 1 is a cylinder block having a cylinder 2, 3 is a cylinder head joined to the upper surface of the cylinder block 1, and 4 is a cylinder block having a cylinder 2. The piston 4 is fitted into the cylinder 2 so as to be able to reciprocate, and a cavity 4a for forming a combustion chamber 5 is formed in the top surface of the piston 4.

On the other hand, although not shown, the cylinder head 3 includes an @ air port that supplies intake air to the combustion chamber 5, and a port that supplies intake air to the combustion chamber 5.
Due to the arrangement shape of the intake boat, 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 do so.

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 fuel injection 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 at the tip side (lower side in the figure) and a fuel injection hole 8 facing the combustion chamber 5 at the rear end side (upper side in the figure). Pump (not shown)
The nozzle body 10 includes a nozzle body 10 in which a fuel inlet 9 connected to each opening opens, and a spring chamber 12, a needle valve support hole 13, and a fuel pressure chamber 14 are arranged in this order from the rear end side to the front end side. These cavities IJ are arranged coaxially with the fuel nozzle holes 8 and in communication with each other. Further, the L fuel inlet 9 and the fuel pressure chamber 14 (fuel injection hole 8) are communicated through a fuel II passage 15 formed in the nozzle body 10. Furthermore, a needle valve 16 is fluid-tightly supported by the needle valve support hole 13 and slidably fitted in the cavity from the spring chamber 12 to the fuel injection hole 8. a spring receiving portion 16a disposed within 12;
A pressure receiving part 16 receives the fuel r1 pressure in the fuel pressure chamber 14.
b, the valve part 16c for opening and closing the fuel r1 injection hole 8, and the throttle part 16d arranged in the fuel injection hole 8, and the throttle part 16d and the wall surface of the fuel injection hole 8. A certain gap is formed between them.

Further, a nozzle spring 17 for urging the needle valve 16 in the closing direction is compressed in the spring chamber 12, and high-pressure fuel from the fuel injection pump flows through the fuel passage 15 from the fuel T'l 1 inlet 9. When the fuel is introduced into the fuel pressure chamber 14, the needle valve 16 is opened against the urging force of the nozzle spring 17 due to the action of the fuel pressure on the pressure receiving part 16b of the needle valve 16, and the fuel is introduced into the fuel injection hole. 8 and into the combustion chamber 5 of the engine, and at that time, the gap between the throttle part 16d and the wall surface of the fuel injection hole 8 changes depending on the lift amount of the needle valve 16. The lift m and the frontage area of the fuel injection hole 8 are configured to change.

That is, the relationship between the lift m and the opening area of the needle valve 16 is as shown in FIG. Then, the opening area of the fuel nozzle hole 8 is kept substantially constant by the throttle of the fuel nozzle hole 8 of the throttle part 16d, and then the needle valve is closed as the throttle part 16d escapes from the fuel nozzle hole 8. After shifting to a proportional change range in which the opening area of the fuel nozzle hole 8 increases in proportion to the lift amount of 16, it is lifted to the full lift position.

In addition, in FIG. 2, 19 is a fuel discharge passage,
There is a device for discharging leaked fuel Fl leaking 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 a fuel tank (not shown) outside the nozzle. .

Furthermore, the spring chamber 12 (Q side nozzle body 10
A cylinder 11 that communicates with the spring chamber 12 is formed on the needle valve 16 and the +i′i+ axis, and the cylinder 11 communicates with the spring chamber 12 through the pressure passage 20.
It is connected to an F1 power supply (not shown) that uses fuel as a pressure medium. Further, from the cylinder 11 to the spring chamber 12
t, ■Branzil member 18 that coincides with the axis of needle valve 16 is 1! ! ! It is fitted freely for the first time. The plunge member 18 is connected to the spring chamber 12.
a rod portion 18a disposed within the cylinder, a plunger portion 18b fitted within the cylinder 1, and a rod portion 1ε.
The flange part 18 is located between the plunger part 3a and the plunger part 18b.
c, the flange 18G is movable over a stroke range until it comes into contact with the rear end wall of the spring chamber 12 and a stopper member 27 disposed at an intermediate portion of the spring chamber 12; The needle valve 1611 of the plunger member 18 is caused by the contact of the portion 18c with the stopper member 27.
When the movement to 11 is M-controlled, the rod 118
The tip of the plunger member 18, such as 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, the plunger portion 1 of the plunger member 18
The needle valve 16 is opened by a predetermined pressure acting on the rear end surface of the needle valve 8b.
The lift m is suppressed.

Further, the plunger portion 18b of the plunger member 18
In the pressure passage 2o communicating with the end face, the fuel discharge oil w119 is connected to the outside part of the nozzle body 10 via the communication passage 28, and the pressure passage 2o is connected to the connection part of the pressure passage 20 with the communication passage 28. Pressure control valve 21 consisting of a duty valve that controls to reduce the pressure within 20
is installed.

To explain the control system for operating the pressure valve 21, 22 is a rotation speed sensor for detecting the engine rotation speed, 23 is a load sensor for detecting the engine load condition, and 24 is an atmospheric pressure sensor. Atmospheric pressure sensor for detecting high altitude from fluctuations, 25 is each of the above sensors 2
2, 23. Solenoid drive circuit 2 for receiving the output of 24 and starting the duty solenoid of the pressure control valve 21
6, which controls the operation of the above control circuit 2.
5 and the solenoid drive circuit 26 constitute two I41j control devices that control the operation of the pressure 1111 all valve 21 according to the operating state of the engine.

The t11J1m device 29, for example, as shown by the solid line in FIG.
A low duty signal is sent to the m valve 21 to increase the fuel pressure applied to the plunge 17 member 18, and when the engine is in a high load state approaching full load F/L and in a high rotation state, the pressure control valve 21 is The fuel pressure applied to the plunger member 18 is controlled to be lowered by sending a high duty ratio signal, and the pressure acting on the plunger member 18 is decreased as at least one of engine speed and load increases. As shown by the broken line in Figure 4,
In a state where atmospheric pressure is reduced at high altitudes, the pressure acting on the plunger member 18 can be lowered by setting the duty ratio of the duty ratio signal to be corrected to be high in a high-angle vJ region, for example, in a region of 3/4 load or more. f, II 1711 to increase the injection rate.

Note that the pressure passage 20 mentioned in 1.1 may be supplied with the fuel supplied to the fuel II inlet 9 in a branched manner, or may be supplied with pressure from a separate pressure source; When using the pump discharge pressure, it is preferable to interpose a check valve between the two so that the pressure in the pressure passage 20 does not act on the fuel P4 inlet 9.

Next, to explain the operation of the above embodiment, basically, when high-pressure fuel is force-fed from the fuel injection pump to the fuel injection nozzle 7, the high-pressure fuel is transferred from the fuel inlet 9 of the fuel injection nozzle 7. Fuel is introduced into the pressure chamber 14 through the fuel passage 15, presses the pressure receiving part 16b of the needle valve 16 in the nuclear fuel pressure seedling 14, and moves the needle valve 16 against the biasing force of the nozzle spring 17. By opening the needle valve 16, the fuel in the fuel pressure chamber 14 is injected and supplied to the combustion chamber 5 of the engine through the fuel injection hole 8. Then, when the lift ω of the needle valve 16 increases due to an increase in the fuel pressure introduced into the fuel pressure chamber 14 and the spring receiving portion 16a comes into contact with the plunger member 18, the needle valve 16 is moved against the plunger member. It will lift together with 18.

Further, the fuel f+ introduced from the pressure source into the cylinder 11 of the 1n9A injection nozzle 7 through the pressure passage 2o acts on the rear end of the plunger member 18 in the cylinder 11, moving the plunger member 18 toward the needle valve 16 side. By applying pressure to the plunger member 18, the lift operation of the needle valve 16 after the spring receiving portion 16a comes into contact with the plunger member 18 is controlled.

Regarding 6111m for this needle valve 16, the fifth
Explaining along the IIIwJ flowchart shown in the figure, the rotation speed signal from the rotation speed hinge 22 is input to the start bond step S1, and the load signal from the load hinge 23 is input to the 1lJIIIllff 29 in the next step S2. Thereafter, in step S3, the duty ratio corresponding to the engine operating state is read from a pre-stored duty ratio map based on the rotational speed signal and the load signal, and then in step S4, the duty ratio corresponding to the engine operating state is read from a pre-stored duty ratio map. An atmospheric pressure signal is input, and based on this atmospheric pressure signal, it is determined in step 85 whether or not it is a highland, that is, it is determined whether the atmospheric pressure is below the atmospheric pressure corresponding to an altitude of 1000 m, for example. If this determination is No (lowland), step S8 The duty solenoid of the pressure control valve 21 is driven according to the duty ratio read in step S3 above, and the fuel applied to the 0752917 member 18 by the pressure 1lIIIll valve 21 is fl,! Iff1l is done.

For each bond, the process returns to step S1 and the step of placing each bond is repeated.

On the other hand, when the judgment in step S5 is YES (highland), it is judged in step S6 whether the C engine load is 3/4 load or more based on the n load signal, and when YES (a load), step S7'r is carried out. Perform decoty ratio correction. This correction is to make the du-eye ratio read in step S3 large (“1”, and step S
What about 8? The de:2-isolenoid of the LucaIIIIIII valve 21 is driven in accordance with the determined duty ratio. Further, when the determination in step S6 is No (low load), the decoupling solenoid of the pressure control valve 21 is driven in step S8 with the same duty ratio as in the lowland without performing duty ratio correction.

This basically means that even in lowlands and highlands,
When the engine is in a low-load, low-speed region, a low duty ratio signal is sent from the m-control device 29 to the pressure control valve 21, so that the fuel pressure applied to the plunger 1 member 18 is increased to increase the fuel pressure applied to the plunger member 18. 18 increases the lift resistance force of the needle valve 16, and this plunger member 1
Due to the increase in the lift resistance force of the needle valve 8, the lift of the needle valve 16 is suppressed when the throttle part 16d is in the throttle range where the fuel injection hole 8 is throttled due to the spring receiving part 16a coming into contact with the plunger member 18. By suppressing the lift of the needle valve 16 in this throttle range, a state in which fuel is injected at high speed from the fuel injection hole 8 is created for a long period of time, promoting atomization of the fuel injection, and improving the ignitability of the fuel. , the combustibility is increased, the exhaust of IC is reduced, and the emission performance is improved. Furthermore, when the engine is in a high load and high rotation range, a high duty ratio signal is sent from the control m+ system to the pressure control valve 21, so that
The fuel pressure applied to the plunger member 18 becomes lower, and the lift resistance force of the plunger member 18 on the needle valve 16 decreases.
d is lifted smoothly without being subjected to lift suppression [, II] until it reaches the lift position in the proportional change range while the fuel d escapes from the fuel nozzle hole 8, or the full lift position after the throttle part 16d completes its escape. ,the result,
The amount of fuel injected into the engine is ensured, and the engine output can be improved.

Furthermore, at high altitudes where atmospheric pressure has decreased, one engine can
/4 load or higher, the duty ratio is set to a value that is relatively higher than the change in duty ratio due to changes in engine speed and load at low altitudes, and this duty ratio signal is sent from the control device 29 to the pressure By being sent to the control valve 21.

The fuel pressure applied to the plunger member 18 becomes relatively low, and the lifting resistance force of the plunger member 18 on the needle valve 16 decreases, and as the fuel injection rate improves, smoke generation is suppressed.

Note that the present invention is not limited to the above embodiments, but
There are also variations of the gods. For example, in the above embodiment, in the 1':S area where the atmospheric pressure has decreased, the pressure horn applied to the blank member 18 in r1 is lowered in the high load range. However, in addition to this, the pressure acting on the plunger member 18 is corrected to be higher in the low load/low rotation range, and the injection rate is reduced to reduce white smoke to suppress -10 emissions. You can do it like this.

On the other hand, regardless of whether the engine is at a low altitude or a high altitude, white smoke is likely to be emitted when the engine is in a rocky state. (low intake air compression temperature),
When the engine is in a white smoke generating operation state, the pressure applied to the plunger member 18 may be increased to improve the combustibility of the fuel and reduce the generation of white smoke.

In addition, by applying supercharging to a J diesel engine and increasing the pressure applied to the plunger member 18 when the supercharging pressure of the intake air is low, the distribution of fuel to the intake air in the combustion chamber is improved and the combustibility is improved. It is also possible to ensure fuel injection 11ffi and improve engine output by lowering the pressure applied to the plunger member 18 when the supercharging pressure of intake air is high.

In general, it is applied to a diesel engine equipped with an fJ# air recirculation system, and when the exhaust gas recirculation rate is large, the pressure applied to the plunger member 18 is increased to a high If, thereby preventing the deterioration of smoke. Hikiru.

Furthermore, in the configuration of the above embodiment, the strength of the intake swirl generated in the combustion chamber of the engine can be controlled.
By adding a swirl control device that simultaneously controls the plunger pressure and swirl according to the operating condition of the engine, it improves emission performance in the low load range of the engine and reduces smoke generation in the low speed range. It may also be possible to reduce this and increase the output direction in the high speed range.

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

[Brief explanation of the drawing]

Fig. 1 is a vertical 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 vertical cross-section of one nozzle (fuel injection), and Fig. 3 is a fuel injection Figure 1 shows the relationship between the lift of the needle valve in the nozzle and the opening area of the fuel nozzle hole. Figure 4 shows the relationship between the engine operating status and the duty ratio signal output to the pressure control valve, and the duty ratio at high altitudes. An explanatory diagram showing the correction, FIG. 5 is a flowchart of the control system. 5... Combustion chamber 7... Fuel injection nozzle 8... Fuel injection hole 9... Fuel injection hole [1
10... Nozzle body 11... Cylinder 14... Fuel pressure chamber 15... Fuel passage 16... Needle valve 16c...・・・
Valve part 16d... Throttle part 17... Nozzle spring 18... Plunger member 18a...
Rod part 18 [)...Plunger part 20...
...Pressure passage 21 ...Pressure series control valve 22
...Rotation speed hinge 23...9 direction sensor 25...Clever 11 circuits 26...Solenoid drive 1 path per day 29...a , II rR apparatus Fig. 1 Fig. 2

Claims (1)

[Claims] (1) A plunger member is provided that is aligned with the axis of the needle valve, has one end facing the needle valve, and is slidable in the axial direction, and applies a predetermined pressure to the other end surface of the plunger member to open the needle. In a diesel engine fuel injection device having a bottle-type fuel injection nozzle configured to suppress the valve rift (-can) at a predetermined pressure, pressure is applied to the pressure passage communicating with the other end surface of the plunger member of the bottle-type fuel injection nozzle. A control valve is installed (C), and the pressure acting on the plunger member is reduced to 0 (lower) as at least one of the engine speed and the load increases, and the pressure acting on the plunger member is reduced to zero (C) in a high load range when atmospheric pressure decreases. 1. A fuel injection device for a diesel engine, characterized in that a control device is provided for driving a pressure control valve so as to avoid a further drop in pressure.