JPH048311Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an injection pressure adjustment device for a fuel injection device that maintains a constant pressure difference between the intake pipe internal pressure of the fuel injection valve section and the fuel supply pressure. The present invention relates to an injection pressure adjustment device for a fuel injection device, which is equipped with a pressure regulator and a low-pressure pressure regulator, and is capable of obtaining different fuel injection amounts in normal times and under high load in the valve opening pulse of a fuel injection valve.

The injection amount can be increased by increasing the valve opening pulse width, but if it is necessary to increase the minimum injection amount accuracy,
It is not preferable to increase the valve opening pulse width, and it is also not preferable to increase the nozzle hole diameter. for example,
Since fuel increases or decreases in proportion to the valve opening pulse when injected, the injection amount range has traditionally been expanded by changing the valve opening pulse width, but the valve opening pulse width can be increased up to a certain limit. Then, the fuel flow rate not only does not increase but also becomes extremely unstable. Furthermore, when the nozzle hole diameter is increased, the accuracy of the minimum injection amount decreases, and the injection becomes unstable.

An object of the present invention is to provide an injection pressure adjustment device for a fuel injection device based on the above viewpoint, which can increase the maximum injection amount without increasing the valve opening pulse width while maintaining the accuracy of the minimum injection amount. The pressure regulator is a high-pressure regulator and a low-pressure pressure regulator with two different heights, and the back pressure chamber of the high-pressure pressure regulator and the back pressure chamber of the low-pressure pressure regulator are communicated with the intake pipe where fuel is injected, and the high-pressure The feature is that either one of the low-pressure pressure regulator and the low-pressure pressure regulator can be forcibly closed.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the device according to the invention in longitudinal section. An injector 2 receives fuel from a fuel supply path 1 that can freely release excess pressure to a fuel tank (not shown), and injects the fuel into an intake pipe 9. A high-pressure fuel return port 3 and a low-pressure fuel return port 4 that can freely release excess pressure from the fuel tank face the fuel supply path 1, and the high-pressure fuel return port 3 is connected to a valve of a diaphragm-type high-pressure pressure regulator 5. The low-pressure fuel return port 4 is configured to be openable and closable by the valve body 11 of the diaphragm-type low-pressure pressure regulator 6 by the body 10 .

The high-pressure pressure regulator 5 controls the pressure during high-speed, high-load operation, and controls the high pressure within the fuel supply path 1. The high-pressure pressure regulator 5 has a positive pressure chamber 12 and a back pressure chamber 7. The positive pressure chamber 12 and the back pressure chamber 7 are isolated via a diaphragm 14, and the back pressure chamber 7 is communicated with the intake pipe 9. There is. The valve body 10 is fixed to a diaphragm 14 and is given a closing habit by a spring 16.

The low-pressure pressure regulator 6 is used for pressure control during normal low-load operation, and controls the upper limit of the low pressure within the fuel supply path 1. The low pressure pressure regulator 6 has a positive pressure chamber 13 and a back pressure chamber 8, the positive pressure chamber 13 and the back pressure chamber 8 are isolated via a diaphragm 15, and the back pressure chamber 8 is communicated with the intake pipe 9. There is. The valve body 11 is fixed to a diaphragm 15 and is given a valve closing habit by a spring 17.

During normal operation, the valve body 10 of the high-pressure pressure regulator 5 keeps the high-pressure fuel return port 3 closed, and the valve body 11 of the low-pressure pressure regulator 6
The valve only opens when the pressure exceeds a low predetermined pressure, and the pressure inside the fuel supply path 1 is released to the fuel tank.

In order to be able to use the high-pressure pressure regulator 5, which has a valve body 10 that opens at a pressure higher than the pressure at which the valve body 11 of the low-pressure regulator 6 opens, the low-pressure pressure regulator 6 must not be operated. It is necessary to do so. That is, it is necessary to prevent the valve body 11 from opening, and the solenoid 18 is used in this embodiment as a mechanism for this purpose. The solenoid 18 has a movable iron core 20 that rises when a voltage is applied to the electromagnetic coil 19. As the movable iron core 20 rises, it presses the valve body 11 against the low-pressure fuel return port 4, thereby reducing the pressure in the positive pressure chamber 13 and the back pressure chamber 8. Regardless of the situation, the low pressure fuel return port 4 is forcibly closed. The voltage is applied to the electromagnetic coil 19 when the speed and load are high speeds and high loads exceeding predetermined values and when the valve opening pulse width reaches its maximum.

In the device of the present invention having the above-mentioned configuration, when the load is low, no voltage is applied to the electromagnetic coil 19 of the solenoid 18, as shown in FIG.
Since the movable iron core 20 is in the lowered state, the pressure within the fuel supply 1 is maintained below the valve closing pressure by the low pressure regulator 6.

During high-speed, high-load operation, a voltage is applied to the electromagnetic coil 19, and the movable core 20 is pushed up to press the valve body 11 against the low-pressure fuel return port 4, so that the fuel reaches the valve opening pressure of the high-pressure regulator 5. The pressure within the supply path 1 will increase.

Therefore, during high-speed, high-load operation, the pressure of the fuel supplied to the injector 2 is high, and even if the valve opening pulse width or nozzle hole diameter remains the same as during low-load operation using the low-pressure pressure regulator 6, the pressure of the fuel supplied to the injector 2 is high. amount of fuel will be injected.

FIG. 2 is a diagram showing how the valve opening pulse width and fuel injection amount change with changes in pressure, and the diagram shows the increase in flow rate when the fuel supply pressure increases. In the figure, symbols P ₁ and P ₂ indicate fuel supply pressure.
FIG. 3 shows an example of a valve opening pulse in the form of a waveform. FIG. 4 shows a second embodiment of the present invention.

FIG. 4 shows a configuration in which the high pressure regulator 5 is forcibly opened and closed, and a valve body 10 integrated with the diaphragm 14 of the high pressure regulator 5
The movable core 20' of the solenoid 18' is connected to the movable core 20' of the solenoid 18'.During normal operation, voltage is applied to the electromagnetic coil 19', and the movable core 20' resists the elastic force of the spring 16.
0' has been lowered. That is, during low load operation, the high pressure fuel return port 3 is in an open state.

During high-speed, high-load operation, voltage application to the electromagnetic coil 19' is cut off, and the valve body 10 closes the high-pressure fuel return port 3 by the pressing force of the spring 16.

On the other hand, in the pressure regulator 6 for low pressure, the valve body 11 is always connected to the fuel return port 4 for low pressure due to the elastic force of the spring 17.
is closed, and the low pressure fuel return port 4 is communicated with the positive pressure chamber 12 of the high pressure regulator 5.

In addition, a fuel supply path 1 that can freely supply fuel to the injector 2 communicates with the positive pressure chamber 13 of the low pressure pressure regulator 6, and the back pressure chamber 7 of the high pressure pressure regulator 5 and the back pressure chamber 8 of the low pressure pressure regulator 6. The structure in which is connected to the intake pipe 9 is the same as in the first embodiment.

As is clear from the above explanation, when the device of the present invention starts high-speed/high-load operation, it is possible to increase the pressure in the fuel supply path, and this pressure increase can increase the amount of fuel injection. Stable minimum injection amount and high speed without increasing the valve opening pulse width or increasing the nozzle hole diameter.
This has the excellent advantage of allowing an increase in the amount of fuel injection during high-load operation.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing the first embodiment of the device of the present invention, Fig. 2 is a diagram showing that the valve opening pulse width and fuel injection amount change depending on changes in fuel supply pressure, and Fig. 3
The figure is a waveform diagram showing an example of a valve opening pulse, and FIG. 4 is a sectional view of the second embodiment. 1...Fuel supply path, 2...Injector, 3...
...High pressure fuel return port, 4...Low pressure fuel return port,
5... Pressure regulator for high pressure, 6... Pressure regulator for low pressure, 7, 8... Back pressure chamber, 9... Intake pipe, 10, 11... Valve body, 12, 13... Positive pressure chamber, 14, 15...Diaphragm, 16,17...
...Spring, 18,18'...Solenoid, 19,1
9'...Electromagnetic coil, 20, 20'...Movable iron core.

Claims (1)

[Scope of utility model registration request] A high-pressure fuel return port 3 and a low-pressure fuel return port 4 are connected to the fuel supply path 1 of a fuel injection device that injects fuel in the fuel supply path 1 through an injector 2, which allows excess pressure to be freely released into the fuel tank. A high-pressure pressure regulator 5 that can be opened and closed is provided at the high-pressure fuel return port 3, and a low-pressure pressure regulator 6 that can be opened and closed is provided at the low-pressure fuel return port 4. and the back pressure chamber 8 of the low-pressure pressure regulator 6 is communicated with the intake pipe 9 through which the injector 2 injects fuel, so that either the high-pressure pressure regulator 5 or the low-pressure pressure regulator 6 can be forcibly closed. An injection pressure adjustment device for a fuel injection device, characterized by: