JPS5865964A - Fuel injector for internal-combustion engine - Google Patents

Abstract

PURPOSE:To slow the rise of the injection rate by forming a notched part on a spool valve in the pressure source pressure introducing part in the pressure supply system for driving the plunger of a fuel injection pump and partly opening the supply port of the spool valve in the initial stage of injection. CONSTITUTION:The first solenoid valve 24 is connected to the hydraulic oil chamber 15 of a spool valve and a fuel feeding pressure source 14 through a conduit 30. The second solenoid valve 25 is connected to the hydraulic oil chamber 15 of the spool valve and a fuel tank 16 in low pressure through a conduit 40. The third solenoid valve 26 is connected to the return port (b) of the spool valve through a conduit 50 and a throttle 22, and further connected to the fuel tank 16 through the conduit 50. A notched part 100 is formed at the edge on the supply port (a) side of the spool 3, and the area of the flow passage for introducing fuel from the fuel supply pressure source 14 to the hydraulic oil chamber 21 of the fuel compressing chamber is small in the initial stage of injection and large in the latter stage.

Description

[Detailed description of the invention] It relates to a fuel injection device.

In recent years, from the viewpoint of cleaning engine exhaust gas and saving energy, it has become necessary to increase the pressure, increase the injection rate, and complicate timing control in fuel injection devices, and various proposals have been made accordingly. As one of these, an electronically controlled hydraulically driven unit injector has been developed. However, in this type of unit injector, when the pressure is increased and the injection rate is increased, the injection rate increases rapidly, which tends to increase engine noise. Furthermore, it has been found that when the injection rate is increased rapidly, that is, when the start-up is rapid, not only noise but also an increase in NOX concentration occurs. Therefore, in the above-mentioned type of unit injector, it is desired to achieve high pressure and slow the rise of the injection rate.

However, it has been extremely difficult to change the injection rate pattern both in conventional conventional fuel injection devices and in the above-mentioned type of unit injector.

The object of the present invention is to form a notch in the stool valve of the pressure source pressure introduction part of the pressure supply system that drives the noranger, and to partially open the supply port of the stool valve at the initial stage of injection. It is an object of the present invention to provide a fuel injection device which makes the increase small and makes the rise of the injection rate gradual.

Another object of the present invention is to provide a fuel injection device that can obtain a desired injection rate pattern with a simple and inexpensive structure. The invention will be explained below by way of examples with reference to the accompanying drawings.

Referring to FIG. 1, a fuel injection device H10 according to the present invention
is shown and the device includes an injector 1, a control device 60 and a fuel supply pressure source 14. The injector 1 has a stool valve, a fuel compression device, an injection nozzle device and a solenoid valve device. The stool valve includes a stool 3, a spring 3a pressing the stool valve in one direction, and a hole 2 accommodating the stool. The hole 2 is formed with a supply port (a) and a return port (b), and also defines a hydraulic oil chamber 15 between it and the left end surface of the stool 3. The fuel compression device of the injector 1 includes a large-diameter piston 6, a hole 4 that accommodates the piston, and a nolunger 7.
, a hole 5 for accommodating this, a hydraulic oil chamber 21 defined between the large diameter piston and the hole 4, and a fuel chamber 12 defined between the nolunger 7 and the hole 5. . The injection nozzle device of the injector 1 includes a fuel injection nozzle 8 and a spring 8a that presses the fuel injection nozzle. The solenoid valve device of the injector 1 includes six two-bottom two-position solenoid valves 24, 25°26,
The first electromagnetic valve 24 is connected to the hydraulic fluid chamber 15 of the stool valve and the fuel supply pressure source 14 via a conduit 30, respectively. The second electromagnetic valve 25 is connected via a conduit 40 to the hydraulic oil chamber 15 of the stool valve and to the low-pressure fuel tank 16, respectively. In addition, the third lightning solenoid valve 26 is connected via a line 50 and a throttle 22 to the return port (b) of the stool valve, and is further connected via a line 50 to the low-pressure fuel tank 16. Stool valve supply port) a is pipe line 30
', 30 to the fuel supply pressure source 14. The fuel chamber 12 of the fuel compression device communicates with a fuel supply pressure source 14 via a check valve 13 and a line 30'' and with the nozzle 8 via a passage 8b. 21 is the stool 3 in the hole 2 of the stool valve
Depending on the position of the stool valve, it communicates with either the supply port (a) or the return port (b) of the stool valve.

The fuel supply pressure source 14 includes a fuel tank 16' and a filter 17.
, a bong 7''18, a pressure regulating valve 19 provided in a bypass line of the pump, and a rice storage device 20.

Referring to FIG. 2, the control device 60 includes the controller 23
and sensors S] to S6. Sensor S1 is the engine rotation speed, sensor S2 is the accelerator pedal depression, sensor S3 is the engine temperature, sensor S4
indicates the engine cylinder mark, sensor S5 indicates an emergency situation such as fuel leakage from piping or engine overrun, sensor S6
detect the pressure of the fuel pressure supply source 14, respectively.

The controller 23 includes an injection amount setting circuit P1, an injection start timing setting circuit P2, a first calculation circuit A1 that determines the injection rate,
It includes a second calculation circuit A2 that determines the injection start timing and an output amplification circuit A3. The first calculation circuit A1 calculates the energization time for the sixth solenoid valve 26 based on the signal from the sensor 81°S2. Second calculation circuit A2
is sensor S1. S2. Based on the signal from S3, the deviation of the start time of energization to the first electromagnetic valve 24 with respect to the cylinder mark is calculated. The output amplifying circuit A3 determines the crank position and energizes the solenoid valves 24, 25, 26 of the related cylinders at a predetermined timing. This output amplifier circuit A3
Normally, the first and sixth solenoid valves 24 and 26 are energized for a certain period of time, but the energization is stopped in response to an emergency signal from sensor S5 or a pressure source pressure signal from sensor S6, or It is also possible to leave the power on.

Referring to FIG. 4, the stool valve of FIG. 1 is shown enlarged. The supply port a and the return port b of the stool valve are formed in the hole 2 in the form of an annular groove, and the stool 3 is formed with a notch 100 in the edge on the side of the supply port a, as shown in FIG.

The fuel injection device 10 shown in FIG. 1 operates as follows.

In the state shown in FIG. 1, the first solenoid valve 24 is energized at time A, and its two ports are in a communicating state (hereinafter, "open").
), fuel is introduced from the fuel supply pressure source 14 into the hydraulic fluid chamber 15 of the stool valve, causing the stool 3 to move to the right against the force of the spring 3a. During this time, the two ports of the second solenoid valve 25 are in a non-communicating state 8 (hereinafter referred to as closed).
It is placed in As the stool valve 3 moves to the right in the bore 2, the return port)b is closed and then the supply port)a is opened. Since the stool 3 is formed with the notch 100 as described above, the moving distance of the stool 3, that is, the opening area of the supply port a with respect to the rift I is as shown by the solid line in FIG. That is, spool 3
When the supply port (a) moves as far as the oil-tight seal, the supply port (a) begins to open, but since only the portion corresponding to the notch 100 of the spool 3 opens, the opening area of the supply port (a) is small.

Since the supply bow (a) of the axis of the notch 100 of the stool 3 further begins to open over the entire circumference, the rate of increase in the opening area increases. In FIG. 6, the open area of the feed port for a conventional stool lift without notches is shown in dashed lines.

In this way, the area of the flow path introduced from the fuel supply pressure source 14 to the hydraulic oil chamber 21 of the fuel compression device is small at the early stage of the injection start time and becomes large at the latter stage. Therefore, the downward pumping speed of the large-diameter piston 6 of the fuel compression device, and thus the silane 7, is slow at the beginning of injection and becomes fast at the end of the injection, so that the injection rate pattern becomes as shown by the solid line for the 71st strain. On the other hand, in a conventional stool without a notch, the opening area of the supply port increases rapidly from the W period of the start of injection, as shown by the broken line in Figure 6, so the injection rate pattern changes as shown in Figure 7. as shown by the broken line. Based on experiments, it has been found that the effect of slowing down the rise of the injection rate pattern is significant. In this way, when the hydraulic oil is introduced into the hydraulic oil chamber 21 of the fuel compression device, the granulator 7
is driven downward to inject the fuel in the fuel chamber 12 through the passage 8b and the nozzle 8. At this time, the fuel in the fuel chamber 12 is prevented from flowing back to the fuel supply pressure source 14 via the conduit 30'' by the check valve 13.

Next, the first solenoid valve 24 is de-energized at time B, and
After the two ports are placed in the closed state, the second solenoid valve 25 is energized at time C to open the two ports and the hydraulic fluid chamber 15 of the stool valve is energized. The fuel is directed into the low pressure fuel tank 16, which causes the stool 3 of the stool valve to move to the left in the bore 2 under the force of the spring 3a. As the spool 3 moves to the left in the hole 2, the supply port a) is closed and then the return port b is opened. After the stool 3 reaches the left end of the hole 2, the second electromagnetic valve 25 is de-energized (time D). In this state, the sixth solenoid valve 2
6 is energized at time E and its two ports are placed in the open state, the fuel in the hydraulic fluid chamber 21 of the fuel compression device is transferred to the return port b1 of the stool valve, the third solenoid valve 26, and the conduit. 50 and is discharged to the low pressure fuel tank 16. Thus, while the sixth solenoid valve 26 is energized, as fuel is discharged from the hydraulic fluid chamber 21 of the fuel compression device,
Fuel from the fuel pressure source 14 flows into the fuel chamber 12 of the fuel compression device through the line 30'' and the check valve 13, pushing up the large diameter stone 6 and the grunge 7. The amount of fuel injected through the nozzle 8 is determined by the energization time of the third solenoid valve 26.

When the sixth electromagnetic valve 26 is de-energized and closed at time F, the hydraulic oil chamber 21 and the fuel chamber 12 of the fuel compression device
The large-diameter V-stone 6 and the sylanger 7 are stopped so that their respective pressures are balanced according to the area ratio of the large-diameter V-stone 6 and the sylanger 7. The throttle 22 is the fuel chamber 1 of the fuel compression device.
This functions to extend the metering time of fuel within the fuel chamber 2, allowing accurate metering.

The above steps are repeated to supply fuel to the engine. Here, the time A when the first electromagnetic valve 24 is energized and in an open state is variably controlled based on a signal from a sensor SE etc. to optimize the injection timing. Also, the time interval KF during which the sixth solenoid valve 26 is energized and kept open allows a predetermined metering of fuel based on signals from sensors S1 y "'2, etc. The opening/closing times A to F have a certain degree of freedom in setting, and some of these times may be set at the same time.

Further embodiments of the stool 3 are shown in FIGS. 8 to 11. That is, in the embodiment shown in FIG. 8, the stool 3 has a cutout 100 in the form of a chamfer at its end.
The supply port formed by a and increasing curvilinearly with respect to lift provides the FJD area. In the embodiment shown in FIG. 9, the stool 3 is formed with a step-like notch 100b, and the supply port increases in a polygonal manner with respect to the lift.
Provide the opening area of a. In the embodiment shown in FIG. 10, the stool 3 is formed with a plurality of notches 100c and 100d similar to the notch 100 in FIG. 10th
The embodiment shown is an extension of the embodiment shown in FIG. 5, and the plot of opening area versus lift has a pattern similar to that of FIG. 5, although the absolute value changes.

From the point of view of radial mechanical balance, the embodiment of FIG. 10 is advantageous over the embodiment of FIG. 5. In the embodiment shown in FIG. 11, the stool 3 is formed with an annular notch 100θ, and it is noted that the opening area of the supply boat a at the initial stage of injection changes depending on the dimension y in FIG. The embodiment of FIG. 11 is even better than the embodiment of FIG. 10 in terms of radial mechanical balance. Figure 12 is Figure 5 and Figure 8.

11 is a plot of the opening area of the supply boat versus the stool lift for each of the embodiments of FIGS. 9 and 11. FIG.

In the embodiment shown in Fig. 16, instead of forming a notch in the stool 3, a notch 100f is provided in the hole 2 of the stool valve, so that the opening area of the supply de)a to the stool lift is made small at the initial stage of injection. 0 The present invention is applicable not only to the fuel injection device shown in FIG.
] It is applicable even if the number of E power sources, type of hydraulic oil, piping, type and number of solenoid valves, type of stool valve, metering method, etc. are different. Moreover, the present invention is applicable even if the types and number of sensors and control methods are different. Although the controller 23 in FIG. 1 is composed of an analog circuit, it may be digital or a combination thereof.

As mentioned above, according to the present invention, the stool or supply 4 of the stool valve? - A notch is formed in the hole to restrict the introduction of fuel driving pressure at the beginning of injection, thereby making the initial rise and fall of the injection chamber pattern gentle. This provides effects such as reducing the noise of the internal combustion engine and purifying the exhaust gas.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a fuel injection device according to an example of the present invention, FIG. 2 is a block diagram of the control device shown in FIG. Figure 4 is an enlarged sectional view of the stool valve in the device shown in Figure 1, Figure 5 is a perspective view of the stool in Figure 4, and Figure 6 shows the stool valve in Figure 4 and the conventional stool valve. A characteristic diagram of the opening area of a supply boat with respect to a stool lift; FIG. 7 is a diagram showing injection rate patterns of a fuel injection device according to the present invention and a conventional device; FIGS. 8 to 11 are according to another embodiment of the present invention. A perspective view of the stool, FIG. 12 is a characteristic diagram of the opening area of the supply boat with respect to the stool lift in each of the embodiments of FIGS. 5, 8, 9, and 11, and FIG. FIG. 7 is a perspective view of a hole in a stool valve with numbered notches according to another embodiment; In the figure, 1... Injector 3... Stool 6... Large diameter piston 7... Noranger 8... Nozzle
10...Fuel injection device 14...Fuel pressure supply source 15.21...Hydraulic oil chamber 23...Controller 24.25.26...1st. 2nd and 3rd solenoid valves 100.1110a to 100f --- Notch agent Asamura Kōgai 4 people 2nd figure 3rd figure 7 Sono 4th ↓ 1 5th figure 6th figure/P t Figure 8 000 Figure 9 Figure 10 d

Claims (3)

[Claims] (1) A hydraulically driven fuel injection system that includes a switching control valve mechanism that has a stool valve that switches the pressure from a pressure source, a pressure feeding mechanism that has a piston and a flusher that are operated by the pressure, and a nozzle that injects the pressure fed fuel. An oil field driven type fuel injection device, wherein a control port of the switching control valve mechanism that communicates the piston hydraulic oil chamber of the pressure feeding mechanism with the pressure source is formed with an initial opening. (2) The oil field driven fuel injection device according to claim 1, wherein the initial opening is a notch formed in the stool of the stool valve. (3) A hydraulically driven fuel injection device according to claim 1, wherein the initial opening is a notch formed in a spool hole of the spool valve.