JPS59231170A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To permit to inject the fuel with a predetermined pressure even in the low-speed and low-load operating area of an engine by a method wherein the valve opening pressure and the amount of lift of a needle valve are controlled by utilizing leak fuel. CONSTITUTION:The high pressure fuel, sent from a fuel injection pump 2 with pressure, applies the pressure of the fuel to the needle valve 14 in an oil reservoir 15 into the direction of lift of the valve 14. When the lift pressure has become higher than predetermined and the needle valve begins to be lifted, it compresses a spring 18 and, therefore, a force regulating pisotn 21 is tried to push up. Accordingly, the pressure of the leak fuel in a pressure regulating chamber 21 is increased further. According to the pressure increase, a pressure, acting on a piezo element operating for a control valve 28, is changed, the element generates a charge and an electronic controller 5 decreases gradually the voltage for the element in accordance with the electric charge. Accordingly, the resilient force of the spring 18 is weakened and the needle valve 14 is lifted slowly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection valve used in an internal combustion engine such as a diesel engine.

The injection valve that injects fuel into the combustion chamber of an internal combustion engine usually lifts the needle valve against the force of a spring using the pressure of fuel supplied from a square or distribution fuel injection pump, and this lift It is known that a fuel cell is configured to open multiple injection holes and inject fuel toward a combustion chamber.

However, in conventional fuel injection valves, the opening pressure and lift amount of the needle valve are constant, so in low speed and low load operating ranges, the valve opens before the injection pressure has risen sufficiently, resulting in low pressure. Since the fuel is injected, the atomization of the fuel is insufficient, which causes white smoke, noise, etc.

The present invention was developed based on these circumstances, and its purpose is to control the opening pressure and lift amount of the needle valve using leaked fuel, even in low speed and low load operating ranges. The present invention aims to provide a fuel injection valve that can inject fuel at a predetermined pressure.

That is, the present invention causes leakage fuel from a needle valve to act on a spring that pressurizes the needle valve, and adjusts the pressure of the fuel with a control valve to control the spring force applied to the needle valve, thereby increasing the valve opening pressure. An embodiment of the present invention, which is characterized in that the lift amount is adjusted, will be described below with reference to FIGS. 1 to 4.

The fuel injection valve 1 shown in FIG. 1 receives fuel from, for example, a known sub-type fuel injection valve 2. The fuel injection valve 1 shown in FIG. fuel injection bong 7
'2 is driven by an engine 3 and pressure-feeds fuel to the injection valve 1 through a fuel pipe 4. Reference numeral 5 is an electronic controller such as a computer, which detects the engine 30 rotational speed and load condition and controls a control valve to be described later.

The fuel injection valve is constructed by integrally connecting a holder body 10 and a nozzle 1 in the axial direction with a retaining nut 12. The nozzle hole 13 of the nozzle 1 is opened and closed by a needle valve 14, and when the nozzle hole 13 is opened, fuel in the oil reservoir 15 is injected from the nozzle hole 13 into the combustion chamber of the engine. The oil sump 15 is connected to the fuel/mother pipe 4 via a passage 16.
is familiar with

The needle valve 14 is connected to the spring 18 via the pressure bottle 17.
is pushed in the valve closing direction by the urging force of The maximum lift of the needle valve 14 is regulated by the spacer 19.

The spring 18 is housed in a spring chamber 2o formed in the holder body 10. A force adjusting piston 2 is provided at the upper end of the spring chamber 20, and the above-mentioned spring 18 is suspended between the force adjusting piston 2 and the suppressing pin J7.

in.

The force regulating piston 2 faces the pressure regulating chamber 22.

The pressure regulating chamber 22 is located within the holder body 10, and the spring chamber 20 is located within the holder body 10.
The pressure regulating chamber 22 and the spring chamber 20 are formed coaxially with each other, and are communicated with each other by a communication passage 23. A check valve 24 is provided in the communication passage 23 to prevent fuel from flowing back from the pressure regulating chamber 22 to the spring chamber 2 . Further, the pressure regulating chamber 22 communicates with a drain tank 27 via a drain port 25 and a leak passage 26.

The drain port 25 is opened and closed by a control valve 28.

The control valve 28 of this embodiment uses a piezoelectric element that produces both a piezoelectric effect and a piezoelectric reverse effect, and this -bizoelectric piezoelectric element is inserted into the pressure regulating chamber 22. When a voltage is applied to the piezoelectric element, it becomes strained and expands, and the drain lead 29 at the lower end closes the drain port 25.

It is the electronic controller 5 mentioned above that applies voltage to the piezoelectric element, and this electronic controller 5 calculates and applies the voltage to be applied to the piezoelectric element according to the operating state of the engine.

In addition, the piezoelectric element generates a stain by being distorted by the pressure in the pressure regulation chamber 22, and this electric charge is fed back to the electronic controller 5 to control the fuel pressure in the pressure regulation chamber 22. It has also become.

Next, the operation of this embodiment will be explained with reference to FIGS. 2 to 4.

High-pressure fuel supplied from the fuel injection pump 2 is sent to the oil sump 15 via the fuel pipe 4 and passage 16. Oil sump 15
The fuel leaks into the spring chamber 20 through the gap formed between the nozzle 1 and the needle valve 14, and the fuel in the spring chamber 2o fills the pressure regulating chamber 22 via the communication passage 23.

Further, when the drain lead 29 of the control valve 28 opens the drain port 25, leaked fuel in the pressure regulating chamber 22 flows out to the drain tank 27 via the drain port 25 and the leak passage 26. Therefore, in this state, the pressing force of the spring 18 is the initial setting load.

The electronic controller 5 detects the operating state of the engine 3, such as the rotational speed and load, and calculates the voltage to be applied to the piezoelectric element serving as the control valve 28, and outputs the voltage to the piezoelectric element. - The two-zo piezoelectric element has a characteristic in which the relationship between applied voltage and strain is shown in FIG. 2 (4). Therefore, when the electronic controller 5 outputs a large voltage to the piezoelectric element, the piezoelectric element expands and the drain lead 29 at the lower end closes the drain port 25. The relationship between the strain amount of the piezoelectric element and the opening area of the drain port 25 is shown in FIG. 2(B).

As shown in FIG. 3, when the piezoelectric element further expands after the drain port 25 is closed, the pressure regulating chamber 22
of fuel is pressurized. This pressurized fuel presses the adjusting piston 2 according to the pressure receiving area ratio of the adjusting capis 2 and the piezoelectric element, so that the adjusting piston 21 is pushed down and the spring 18 is deflected. Therefore, the spring 18 pushes the suppression pin 17 and the claw needle valve 14 with a spring force greater than the initial setting load. In this way, the amount of expansion of the piezoelectric element and the spring force of the spring 18 are maintained constant.

When high-pressure fuel is fed from the fuel injection bomb f2, fuel pressure in the lift direction is applied to the needle valve 14 in the oil sump 15. When the lift pressure and the valve opening pressure exceed a predetermined value and the needle valve 14 starts to lift, the spring 18 is compressed, so that the adjusting piston 2 tends to be pushed up. Therefore, the leak fuel pressure in the pressure regulating chamber 21 further increases. Therefore, the pressure acting on the piezoelectric element as the control valve 28 changes, causing the element to undergo compressive strain and generate electric charge. This charge is transmitted to the electronic controller 5, and the electronic controller 5 gradually reduces the voltage applied to the piezoelectric element in accordance with this charge. Therefore, the amount of expansion of the two-zo piezoelectric element returns to its original value, the fuel pressure in the pressure regulating chamber 22 that acts on the regulating piston 2 gradually decreases, and the downward force applied to the regulating piston 2 also weakens. The spring force of the spring 18 also weakens and the needle valve 1
4 lifts gently. The lift of the needle valve 14 opens the multiple injection holes 13 and injects fuel.

Under the control of the electronic controller 5, the piezoelectric element is contracted and maintained in this state until just before the drain lead 29 opens the drain boat 25. The needle valve 14 is therefore raised to its maximum lift position.

When the fuel supply from the fuel injection bomb f2 is finished, the oil sump 1
The pressure at 5 decreases and the needle valve 14 begins to descend. At this time, the spring 18 expands, so the pressure in the pressure regulating chamber 22 decreases, and therefore the pressing force acting on the piezoelectric element also decreases.

Therefore, in the piezoelectric element, a charge opposite to that described above is generated due to return strain. The electronic controller 5 detects this reverse charge and applies a voltage to the piezoelectric element so that it expands. As a result, the pressure in the pressure regulating chamber 22 is increased, pushing down the regulating piston 21 and urging the needle valve 14 to descend. Therefore, the needle valve 14 closes quickly to prevent secondary injection.

According to this embodiment, the leakage fuel pressure in the pressure regulating chamber 22 is adjusted by controlling the piezoelectric element by the electronic controller 5 according to the rotational speed and load condition of the engine 3, so that the spring of the spring 18 is adjusted. to control the power,
As shown in Figure 4, by controlling the piezoelectric element, the valve opening pressure can be increased during low rotation and low load operation, and since the fuel is injected at high pressure, it is possible to atomize the fuel and ensure smooth combustion. realizable.

Moreover, since the spring force of the spring 8 is adjusted by controlling the leakage additive, no special fuel supply means is required and the structure is simple.

Note that the present invention is not limited to the first embodiment shown in FIG. That is, in the second embodiment shown in FIG.
The check valve 24 shown in FIG. 1 is eliminated, and the pressure-receiving area of the adjustment piston 21 is made so that the surface facing the pressure adjustment chamber 22 has a larger diameter than the surface facing the spring chamber 20. Note that No. 5 is a bypass leak passage. According to such a configuration, when the control valve 28 made of a piezoelectric element closes the drain port 25, the spring chamber 20 and the pressure regulating chamber 22 are closed.
are connected to each other and are closed containers, the control valve 2
When B is further expanded, the fuel pressure in both chambers 20 and 22 increases simultaneously. The pressure regulating piston 2 is in the pressure regulating chamber 22
Since the pressure receiving area on the spring chamber 20 side is also larger than the pressure receiving area on the spring chamber 20 side, the spring 18 is pushed down. As a result, the pushing down force acting on the needle valve 14 increases, so that the valve opening pressure can be increased. The piezoelectric element is controlled in the same manner as in the first embodiment.

The third embodiment shown in FIG. 6 differs from the first embodiment in that the check valve 24 is abolished, and a lift regulating valve 61 is used in place of the power regulating stone 2. Lift regulation valve 6
The feature is that it is urged upward by a spring 10-62.

In this configuration, the lift regulating valve is formed on the 6th rod and the 9th rod 6
Since the lower end of the needle valve 3 is close to the suppression pin 17, the lift i of the needle valve 14 is controlled. That is, when the fuel pressure in the υ pressure regulating chamber 22 increases due to the expansion of the control valve 28 made of a piezoelectric element, the lift regulating valve 6 is pushed down, and the distance between the lower end of the rod 63 and the upper end of the pressing pin 12 is shortened. It becomes like this. Needle valve 1 is supplied by pressure from fuel injection pump 2.
4 starts to lift, press pin 17 to the above ropes.
Since this occurs, the lift amount of the needle valve 14 is regulated. Therefore, the opening area of the nozzle hole 13 becomes smaller and the injection pressure becomes higher. The control valve 28 made of a piezoelectric element is controlled in the same manner as in the first embodiment, and the amount of descent of the lift regulating valve 6 is increased during low-speed operation of the engine, and the amount of descent is decreased during high-speed operation. If it is made to decrease, the ref)-IN of the needle valve 14 is controlled.

In addition, in the third embodiment, the check valve 2 is similar to the first embodiment.
4 and the lift regulating valve 6 pushes the spring 18, it is also possible to control the lift i and the valve opening pressure at the same time.

Further, a fourth embodiment shown in FIG. 7 shows a case where a piezoelectric element is not used as the control valve 28. control valve 28
is a normal sylanger type, and the fuel in the pressure regulating chamber 22 is pressurized by a pressure regulating spring 7. The control valve 28 is formed with a tenon 9 surface 22, and this tapered surface 72
The opening area of the seat train port 25 is controlled accordingly.

The control valve 28 is pushed upward when the pressure in the pressure regulating chamber 22 increases, but this movement is caused by the spring of the pressure regulating spring 71 so that it operates at a pressure higher than the upward movement start pressure of the regulating male stone 73. Set the power. Note that 74 is an aperture).

In the case of the fourth embodiment, the leakage fuel filled into the spring chamber 20 and the pressure adjustment chamber 22 from the gap between the nozzle 1 and the needle valve 14 is small when the engine 3 is operating at low speed. Do not get high pressure. Therefore, the force adjusting piston 73 descends a little depending on the ratio of the upper and lower pressure-receiving areas and is stopped. When fuel is fed under pressure from the fuel injection pump 2, the needle valve 14 is raised and attempts to raise the adjusting piston 73 via the spring 18, but the adjusting piston 7
3 moves upward, the total volume of the spring chamber 20 and the pressure regulating chamber 22 decreases based on the difference between the upper and lower surfaces of the force adjusting piston 73, so that the pressure in these chambers 20.22 increases. At this time, since the opening area of the drain port 25 is small, the control valve 28
is about to be pushed up against the pressure regulating spring 7. However, room 75 which accommodated pressure regulating spring 7
Since the fuel is regulated by the throttle shift 4, the control valve 28 rises very slowly. For this reason, the adjusting piston 7
3 also slowly rises, and the needle valve 14 slowly lifts.

When the pressure feeding of fuel from the fuel injection pump 2 is completed and the needle valve 14 moves to the closing operation, the control valve 28 is immediately lowered to 13- by the force of the pressure regulating spring 7, and the fuel in the pressure regulating chamber 22 is lowered. Increase the pressure and adjust the adjustment piston 7
By pressing 3, the needle valve 14 is urged to descend immediately.

When the engine 3 is operating at high speed, there is a lot of leakage fuel, so the spring chamber 20. The pressure in both pressure regulating chambers 22 is high, and the control valve 28 is pushed up while the regulating piston 73 is pushed down. As the control valve 28 rises, the opening area of the seat train port 25 becomes larger and this state is maintained.

When the needle valve 14 lifts due to fuel being pumped from the pump 2, the relief fuel escapes through the drain port 25, so the needle valve 14 can be lifted at low pressure even during low speed operation. 13 can be opened quickly.

According to the present invention described in detail above, the pressure of the leaked fuel is controlled by the control valve and this pressure is applied to the spring to control the spring force applied to the needle valve. Valve opening pressure and lift amount can be controlled.

14- Therefore, when the engine is running at low speed, the spring force can be increased to increase the valve opening pressure or to regulate the lift amount, increasing the fuel injection pressure from the nozzle hole to promote atomization and smooth combustion. You can make it happen. Furthermore, since the spring force of the present invention is controlled by using leaked fuel, there is no need for a special fuel supply means, and there are advantages such as a simple structure and a force that can be realized.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention.
The figure is a configuration diagram, and Figures 2 (B) to 4 are characteristic diagrams. FIGS. 5 to 7 are block diagrams showing second to fourth embodiments of the present invention, respectively. 1...Fuel injection valve, 2...Fuel injection pump, 3...
・Engine, 5...Electronic controller, 10...Hoktor & D, 1 node...Nozzle, 14...Needle valve, 18...Spring, 2...Adjustment piston, 2
2... Pressure regulation chamber, 28... Control valve, 25... Drain port, 6... Lift regulation valve. 15-” taste of λ

Claims (1)

[Claims] In a fuel injection valve in which the needle valve is lifted against the spring force by the pressure of the fuel supplied from the fuel injection pump, and the injection hole is opened by the lift of the needle valve and fuel is injected, leakage occurs from the needle valve. The fuel injection system is characterized in that the surgical pressure applied to the needle valve is controlled by a control valve, and the control pressure is applied to the spring to adjust the spring force, thereby controlling the valve opening pressure and lift amount of the needle valve. valve.