JPS60162052A - Fuel injection device for diesel engine - Google Patents

Abstract

PURPOSE:To raise an injection velocity of fuel and accelerate its atomization as well as to prevent white smoke from occurring in such an operating state as especially being liable to produce the white smoke among engine's operating states, by selecting plural fuel discharge passages with operation on a selector valve, while regulating a lift control starting position of a needle valve at discretion. CONSTITUTION:Pressure in high pressure fuel entered into a fuel intake port 9 of a fuel injection nozzle 7 turns to pressure impression for a plunger member 18, limiting lift motion of a needle valve 16. In the case where an engine is in a range where it is liable to produce white smoke, any of a water temperature switch 22, an outside temperature switch 23 and an atmospheric pressure switch 24 comes into a state of being closed whereby a solenoid switch 21 is energized with current and set in close operation. At this state, leak fuel inside a cylinder 11 flowing in from a spring chamber 12 lifted while being discharged out through a passage 19 till a needle valve 16a closes a first fuel discharge passage 19, so that such a state that fuel is spouted at high speed from a fuel injection nozzle 8 is prolonged. With this constitution, atomization in injection fuel is well accelerated and therefore the control of white smoke is thus promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection device that injects and supplies fuel to a diesel engine, and in particular, injects fuel according to the lift amount of a needle valve that lifts in response to fuel pressure This relates to the improvement of a bottle-type fuel injection nozzle in which the opening area of the nozzle hole is changed. In the present invention, the term "bintle-type fuel injection nozzle" is used to include a throttle-type fuel injection nozzle having a comparatively wide throttle range in which the needle valve throttles the fuel injection hole within the lift range of the needle valve. .

(Prior Art) Conventionally, as an example of this kind of bottle-type fuel injection nozzle, as disclosed in, for example, Japanese Patent Application Laid-Open No. 57-151058, 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 at the plunger member, and by applying a predetermined pressure to the one plunger member, lift of the needle valve above a predetermined lift amount is suppressed. By maintaining the throttle range in a closed state for a certain period of time,
There is a so-called central plunger type that can atomize the injected fuel and change the fuel injection rate.

In such a central plunger type fuel injection nozzle, conventionally, as a structure for suppressing lift of the needle valve, a structure around the needle valve is provided at a predetermined portion of the cylinder side wall between the needle valve and the plunger member. A fuel discharge passage (leak passage) is formed to discharge leaked fuel leaked from the gap to the outside of the nozzle, and the pressure acting on the plunger member is used as a fuel pressure horn, and the needle valve moves as the needle valve lifts. When the fuel discharge passage is closed and fuel is sealed in the cylinder between the needle valve and the plunger member, the pushing force from the plunger member is transmitted to the needle valve via the sealed fuel, and the needle There are also known devices that suppress the lift of the valve.

However, with the above-mentioned conventional systems, it is difficult to properly use the functions for atomizing the fuel and changing the fuel injection rate depending on the operating state of the engine, and it is not possible to control engine combustion acceleration, etc. This is especially true when the engine is operating in a state where white smoke is likely to be produced, such as when the engine is not yet warmed up and the coolant temperature is low, such as when the engine is started, or when the outside air temperature is low, or when the atmospheric pressure is low. When the intake compression temperature is low, such as when the intake air compression temperature is low, the ignitability of the fuel becomes poor, the amount of unnatural gas (HC) generated increases, and white smoke is produced in the exhaust gas due to the mixture of the unnatural gas and water vapor. There is problem 7.

(Object of the Invention) The present invention has been made in view of the above points, and its object is to provide a plurality of fuel discharge passages that determine the lift suppression start position of the needle valve described in 1, and to reduce the temperature of the intake air compression temperature of the engine. By appropriately using the plurality of fuel discharge passages and changing the lift suppression start position of the needle valve,
When the engine is still cold, such as when the engine is started, or when the outside air temperature or atmospheric pressure is low, white smoke is likely to be produced, and the injected fuel is atomized to promote its combustion. The aim is to reduce the amount of gas in advance and prevent the generation of white smoke.

(Structure of the Invention) In order to achieve the above two objects, the solution means of the present invention is such that the plunger member closes the fuel discharge passage that opens into the cylinder side wall as described above. J3 is a fuel injection device for a diesel engine having a bottle-type fuel injection nozzle that is pressed to suppress its lift. A two-stage IN with a tool part, and a plurality of fuel discharge passages are provided at predetermined intervals in the cylinder axis direction on the cylinder side wall between the needle valve and the plunger member. Of the respective fuel discharge passages, the first fuel discharge passage is located at a position from 71 within the first stage throttle range by the large diameter throttle portion of the needle valve, and the second fuel discharge passage is located within the first stage throttle range of the large diameter throttle portion of the needle valve. a switching valve that is arranged to correspond to the lift position within the second stage throttle range by the first cotter section and selectively switches the fuel discharge passage; In this case, the lift of the needle valve is suppressed by blocking the first fuel discharge passage of the needle valve, and when the intake compression mixture in the engine is high, the lift of the needle valve is suppressed by blocking the second fuel discharge passage of the needle valve. The valve is equipped with a control device that performs switching control so that lift of the valve is suppressed.

As a result, the nozzle hole area in the throttle range C of the nozzle can be changed in stages according to the rift of the needle valve due to the two-stage structure of the large-diameter throttle part and the small-diameter throttle part of the throttle part of the needle valve. The operating conditions of the engine where white smoke is likely to occur are, for example, the engine cooling water temperature is below 60 degrees Celsius, or the outside temperature is below 15 degrees Celsius, but the atmospheric pressure is below 0.9 atmospheres, for example. In some cases, by controlling the switching operation of the switching valve that is suppressed by the VJ control device, the position at which lift suppression of the needle valve by the plunger member starts is set within the first stage throttle range where the nozzle hole area is small. be.

(Effect of the invention) Therefore, the fuel injection tI of the diesel engine of the present invention
According to the fourth device, a plurality of fuel discharge passages are installed so as to form a fuel-tight state between the needle valve and the plunger member, corresponding to the lift position of the needle valve of the bottle-type fuel nozzle, However, by switching the switching valve, the above-mentioned plurality of fuel discharge passages are switched and the lift suppression start position of the needle valve is arbitrarily adjusted. In the operating state, the lift suppression start position of the needle valve is set to the first stage throttle with a small nozzle hole area by the large diameter throttle part (to keep the nozzle nozzle hole area narrow as a lift position within the range of By increasing the particle size, promoting atomization and improving combustibility, it is possible to reduce gases and HC and prevent the generation of white smoke.

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

FIG. 1 shows a combustion chamber portion 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 the cylinder A cavity 4a for forming a combustion chamber 5 is recessed in the top surface of the piston 4.

On the other hand, although not shown, the cylinder head 3 includes an intake boat that supplies intake air to the combustion chamber 5, and an intake boat 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 includes a glow plug 6 that heats the inside of the combustion chamber 5 when starting the engine, and a glow plug 6 that heats the inside of the combustion chamber 5 when starting the engine.
A bottle-type fuel injection nozzle 7 that injects fuel into the interior.
The fuel injection direction of the fuel injection nozzle 7 is set along the intake swirl.

As shown in enlarged detail in FIG. 2, the bottle-shaped fuel injection nozzle 7 has a fuel injection hole 8 facing the combustion chamber 5 on the tip side (lower side in the figure), and a fuel injection hole 8 on the rear end side (upper side in the figure). Each fuel inlet 9 connected to an injection pump (not shown) is provided with a nozzle body 10, and cylinders 11. Spring chamber 1
2. A needle valve support hole 13 and a fuel pressure chamber 14 are formed, and these cavities are provided coaxially with the fuel inlet 1]9 and the fuel injection hole 8 and in communication with each other. Further, the fuel inlet 9 and the fuel pressure chamber 14 (fuel injection hole 8) are connected to the fuel 11 passage 15 formed in the nozzle body 10.
communicated by. Furthermore, a needle valve 16 is fluid-tightly supported and slidably fitted in the cavity from the cylinder 11 to the fuel injection hole 8. A piston portion 16a that is fitted into the front side portion, a spring receiving portion 16b that is placed within the spring chamber 12, a pressure receiving portion 16c that receives the fuel pressure within the fuel pressure air 14, and the fuel injection It is equipped with a valve part 16d for opening and closing the hole 8, a two-stage, one-piece throttle part consisting of a large-diameter throttle part 168 disposed in the fuel injection hole 8 and a small-diameter throttle part 16 on the distal end side of the large-diameter throttle part 168. Each throttle section 16e, 16f
A certain gap is formed between the fuel nozzle hole 8 and the wall surface of the fuel injection hole 8, respectively. Further, a nozzle spring 17 is provided in the spring chamber 12 to bias the needle valve 16 in the valve closing direction.
is compressed, and high-pressure fuel from the fuel injection pump is injected from the fuel inlet 9! 1 through the passage 15 to the fuel pressure chamber 1
4, the needle valve 16 is closed against the biasing force of the nozzle spring 17 due to the effect of the fuel pressure on the pressure receiving part 16C of the needle valve 16, and the fuel flows into the fuel nozzle hole 8.
The needle valve 16 The lift m and the opening area of the fuel injection hole 8 are configured to change as shown in the lower part of FIG. 3. However, after the needle valve 16 is closed, the large-diameter and small-diameter throttle parts 15e and 16f are first located within the fuel nozzle hole 8, and the fuel nozzle hole is opened by restricting the fuel nozzle hole 8 of the large-diameter throttle part 16e. The opening area of the fuel injection hole 8 is kept extremely small and approximately constant. Due to the throttle of the fuel injection hole 8 at 16f, the opening area of the fuel injection hole 8 becomes slightly larger than the opening area in the first stage throttle range and enters the second stage throttle range where it is kept approximately constant, and then the fuel injection Small diameter slot from hole 8 1:1
The reflux of the needle valve 16 due to the escape of the throttle portion 16f]-
After moving to a proportional change range in which the fuel flow between the nozzle holes 8 increases in proportion to the amount, it is lifted to the full lift position.

Further, a plunger member 18 is slidably inserted into the cylinder 11 by a predetermined stroke by engaging a projection 11a formed on the side wall of the cylinder 11 with an engagement groove 188 formed on the outer peripheral surface of the plunger member 18. . That is, the plunger member 18 is slidably disposed coaxially with the needle valve 16 on the rear end side of the needle valve 16, and the tip of the plunger member 18 is opposed to the piston portion 16a, which is the rear end of the needle valve 16. , so that fuel pressure from the fuel inlet 9 acts on the rear end surface.

Further, in the side wall of the cylinder 11 (nozzle body 10) between the piston portion 16a (rear end portion of the needle valve 16) of the needle valve 16 and the plunger member 18, there is provided a needle valve support hole from the fuel pressure chamber 14 to the needle valve 16. Two fuel discharge passages 1, a first and a second, for discharging leaked fuel leaked into the C-spring chamber 12 and cylinder 11 through a minute gap with the C-spring chamber 13 and into a fuel tank (not shown) outside the nozzle.
9.20 are provided, and the two fuel discharge passages 19°20
is opened into the cylinder 11 at a location separated by a predetermined distance in the axial direction of the cylinder 11 (in the lift direction of the needle valve 16). The opening position of the first fuel discharge passage 19 to the cylinder 11 is when the fuel injection hole 8 is throttled by the large diameter throttle portion 16e of the needle valve 16 and the opening area thereof is kept small. Needle valve 1
On the other hand, the opening position of the second fuel discharge passage 20 to the cylinder 11 is set to a position where it is closed by the piston part 16a of the needle valve 16.
The needle valve 1
It is set at a position where it is closed by the piston portion 16a of No. 6.

Therefore, as the needle valve 16 lifts, its piston portion 16a closes the first fuel initial outlet passage 19, and the cylinder 11 between the piston portion 16a and the plunger portion vJ18.
In a state in which leak fuel is sealed inside, fuel pressure acting on the rear end surface of the plunger member 18 is configured to suppress the lift amount of the needle valve 16 via the sealed leak fuel.

Further, in a portion of the second fuel discharge passage 20 extending outside the nozzle body 10, a permanent electromagnetic on-off valve 21 is disposed as a switching valve for selectively switching each fuel discharge passage 19, 20. ing.

To explain the control system that controls the operation of this electromagnetic on-off valve 21, 22 is a water temperature switch that detects the engine cooling water temperature and opens and closes when the water temperature is below 60°C, and 23 is an external water temperature switch. An outside air temperature switch 24 detects the air temperature and opens and closes when the outside air temperature is, for example, 15°C or lower.
Is it a human pressure switch that opens and closes so that it closes when the pressure is 9 atmospheres or less, and each switch 22, 23, and 24 are connected in parallel? The valve 21 is closed between the IlK magnetic valve and the closed valve. and,
If any of the following conditions apply: the water temperature drops to 60 degrees Celsius or less, the outside temperature drops to 15 degrees Celsius or less, or the atmospheric pressure drops to 0.9 air 11 or less, that is, the intake air compression temperature in the engine is low. In this case, the electromagnetic on-off valve 21 is closed and the leaked fuel is discharged only through the first fuel discharge passage 19.
By blocking the fuel discharge passage 19 with the needle valve 16, the lift of the needle valve 16 is suppressed, and when none of the above conditions apply, that is, when the intake air compression temperature in the engine is high, the electromagnetic opening/closing is performed. The valve 21 is opened to discharge leaked fuel from both the first fuel discharge passage 19.20 and the second fuel discharge passage 20.
A control device 25 is configured to control the needle valve 16 so that the lift of the needle valve 16 is suppressed by closing the needle valve 16 . Note that 26 is a power source.

Next, the operation of the above embodiment will be explained. Basically, when high-pressure fuel is pumped from the fuel injection pump to the fuel injection nozzle 7, the high-pressure fuel is transferred to the fuel inlet 9 of the fuel injection nozzle 7. is introduced into the fuel pressure chamber 14 via the fuel passage 15, presses the pressure receiving part 16G of the needle valve 16 in the fuel pressure nozzle chamber 14, and lifts the needle valve 16 against the urging 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.

Further, the pressure of the high-pressure fuel introduced into the fuel injection nozzle 7 [19] also acts on the rear end surface of the plunger member 18 in the cylinder 11, pressing the plunger member 18 toward the needle valve 16, and this plunger 27 The application of fuel pressure to the member 18 causes the lift operation of the L needle valve 16 to be υ1.
It will be tllll. To explain the control for this needle valve 16, the engine cooling water temperature is lowered to 60°C or lower, the outside temperature is lowered to 15°C or lower, or the atmospheric pressure is lowered to 0.
If any of the conditions for the drop to 9 atmospheres or less apply,
That is, when the engine is in a region where white smoke is likely to occur, the water temperature switch 22. Either the outside temperature switch 23° or the atmospheric pressure switch 24 is closed, and the electromagnetic on-off valve 2
1 is energized and closes. This electricity 111 on-off valve 21
When the needle valve 16 is closed, the piston portion 16a moves through the first fuel discharge passage 19 within its lift range.
Until the cylinder 11 is completely blocked, the fuel in the cylinder 11 that has flowed in from the spring chamber 12 is discharged through the first fuel discharge passage 19, and the piston part 16a is freely lifted using the urging force of the nozzle spring 17 as a resistance force. When the first fuel discharge passage 19 is closed, fuel is sealed in the cylinder 11 between the piston portion 19 and the plunger member 18, and the fuel pressure acting on the rear end surface of the plunger member 18 removes the sealed leak fuel. The pressure is transmitted to the needle valve 16 through the needle valve 16, and the lift is controlled to be suppressed by increasing the valve pressure of the needle valve 16. Therefore, the lift of the needle valve 16 is suppressed as shown by the solid line in the upper part of FIG. 'TIIJ In this way, the large diameter throttle part 16e of the needle valve 16 does not escape from the fuel injection hole 8 and the needle valve 16 is within the 1st stage II throttle range, and this 1st stage throttle range By suppressing the lift of the inner needle valve 16, the state in which fuel is traversed at high speed from the fuel nozzle hole 8 is maintained for a long time, promoting atomization of the injected fuel, increasing the combustibility of the fuel, and preventing it from occurring. Gas reduction, ie, suppression of white smoke caused by 1-IC, is achieved.

On the other hand, if none of the above conditions apply, the electromagnetic on-off valve 21 is kept open due to the inoperation of each switch 22 to 24, and the needle valve is 16 freely lifts using the biasing force of the nozzle spring 17 as a resistance force until the second fuel discharge passage 20 is closed, and the screw part 16a/fi second fuel discharge passage 20
When the valve is closed, a leakage fuel seal is formed between the needle valve 16 and the plunger member 18, and the lift is suppressed. Therefore, as shown by the upper broken line in FIG. The lift is suppressed, and normal white smoke is prevented.

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 Y easel engine.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a vertical cross-sectional view of the main parts of a diesel engine, Fig. 2 is an overall configuration diagram of a fuel injection device, and Fig. 3 is a diagram showing a needle valve lift stone of a fuel injection nozzle. It is an explanatory view showing the relationship between nozzle hole area J3 and needle valve opening pressure. 7...Bintle type fuel injection nozzle, 11...Cylinder, 16...Needle valve, 16e...Large diameter sludge portion, 16f...Small diameter sludge portion, 18...
Plunger member, 19.20...1st. Second fuel discharge passage, 21... switching valve, 25... control IL device. Figure 1 Figure 3 Old lift Figure 2 Todoroki

Claims (1)

[Claims] (1) A slidable plunger member is provided on the rear end side of the needle valve coaxially with the needle valve (), one end of the plunger member is opposed to the needle valve, and fuel pressure is applied to the other end surface. A fuel discharge passage is formed in a cylinder side wall between the needle valve and the plunger member, and the fuel acts on the other end surface of the plunger member when the cough fuel discharge passage is closed due to lift of the needle valve. In a fuel injection device for a Deville engine equipped with a pintle-type fuel injection nozzle configured to suppress the lift of the needle valve by pressure, the throttle portion at the tip of the needle valve of the pintle-type fuel injection nozzle is connected to the opening of the fuel injection hole. A large-diameter throttle part for forming a first-stage throttle range with a small area, and a small-diameter throttle part located on the tip side of the large-diameter throttle part for forming a second-stage throttle range with a large nozzle opening area. The cylinder side wall between the needle valve and the plunger member is provided with a plurality of fuel discharge passages separated by a predetermined interval in the direction of the cylinder axis, and each of the fuel discharge passages Of these, the first fuel discharge passage is located at a lift position within the first stage throttle range by the large diameter throttle part of the needle valve, and the second fuel discharge passage is located at the second stage throttle range by the small diameter throttle part of the needle valve. A switching valve is arranged to correspond to each lift position within the throttle range and selectively switches the fuel discharge passage. The lift of the needle valve is suppressed by the blockage of the first fuel discharge passage, and when the intake air compression temperature flowing into the engine is high, the lift of the needle valve is suppressed by the blockage of the second fuel discharge passage of the needle valve. 1. A fuel injection device for a diesel engine, comprising a control device that performs switching control so as to suppress the fuel injection.