JPH0313423B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device that injects fuel into each cylinder from a common fuel supply source using an injector provided for each cylinder.

In a fuel injection system that injects fuel from a common fuel supply source to each cylinder via an injector, if the pressure of the common fuel supply source is not stable, the injection characteristics between the cylinders will vary. There is a problem. In order to stabilize the pressure on the fuel supply source side and ensure that the injection characteristics between cylinders are uniform and highly accurate, conventionally a common accumulator is installed at the fuel supply source, and this accumulator and each injector are connected with respective piping. measures were adopted. However, this structure not only has a complicated piping structure because there are many pipes connecting the accumulator and each injector and the distance is long, but also because the accumulator is common, pulsating pressure occurs due to the influence of other cylinders, causing pulsation. tends to occur. In order to eliminate the influence of the pulsating pressure of other cylinders, it is possible to increase the size of the accumulator, but this has the disadvantage of increasing the size of the entire injection device.

On the other hand, a structure in which an accumulator is installed immediately before each injector and these accumulators are connected to a fuel supply source can be considered, but this also requires a large number of piping and a long distance between each accumulator and the fuel supply source, so the piping structure is difficult. This is complicated, and in addition, an accumulator is required for each injector, resulting in drawbacks such as an increase in the number of parts and an increase in installation space.

The present invention was developed based on these circumstances, and it simplifies the piping structure, reduces the number of accumulators used, eliminates pulsation caused by the influence of other cylinders, and supplies fuel at equal pressure to each injector. An object of the present invention is to provide a fuel injection device for a multi-cylinder internal combustion engine that can perform the following steps.

That is, in the present invention, each injector is divided into a plurality of groups in which the injection order is different from each other, and a single accumulator is provided for each group, and the fuel is sent from the fuel supply source by this accumulator. The number of piping from the fuel supply source to the accumulator is reduced, and the number of accumulators used is limited to the number of groups.Furthermore, in the accumulator, fuel is distributed to injectors that are separated from each other in the injection order. The device is designed to reduce pulsation even though it is small in size.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In FIG. 1, the number 100 is, for example, a six-cylinder engine. 1a to 1f are injectors provided for each cylinder, and the injection order (explosion order) is set in the order of →→→→→. 2 is a high pressure fuel supply source, and 3 is a low pressure fuel supply source. The high-pressure fuel supply source 2 is connected to high-pressure side accumulators 204 and 205 via pipes 21x and 21y, respectively. One high pressure side accumulator 20
4 are arranged close to injectors 1a, 1b, and 1c of one group whose injection order is far apart, and are connected via pipes 21a, 21b, and 21c, respectively, and the other high-pressure side accumulator 205 is arranged near the injectors 1a, 1b, and 1c whose injection order is far apart. Injector 1 of other group
d, 1e, and 1f, and the pipes 21d, 1f, respectively.
They are connected via 21e and 21f. The low pressure fuel supply source 3 is connected to low pressure side accumulators 304 and 305 via pipes 15x and 15y, respectively. One low pressure side accumulator 304 is connected to one group of injectors 1a, 1b, 1c.
The pipes 15a and 15 are provided adjacent to the pipes 15a and 15, respectively.
The other low-pressure side accumulator 305 is connected to the other group of injectors 1d, 1e, 1f in close proximity via piping 15d, 15e, 15f, respectively.

Each accumulator 204, 205, 304, 3
05 is constructed as shown in FIG. 2 with 24 accumulators, and the capacity of the accumulator 204 is set to be 100 times the maximum value of fuel that can be supplied to a single injector.

The structure of each injector 1a to 1f will be explained using the injector 1a shown in FIG. 3 as a representative. The injector 1a has a switching valve 5, such as a spool valve, which slides left and right in FIG. A small-diameter plunger 8 and a large-diameter piston 9 that slide on each other, and an injection nozzle 10 that receives fuel fed under pressure from the plunger 8.
It consists of three solenoid valves 11, 12, and 13. The inside of the bore 4 on one side of the switching valve 5 is the switching valve operating oil chamber 1.
4, and this chamber 14 communicates with the low pressure side accumulator 304 via the solenoid valve 11, which is a two-way on-off valve, and piping 15a, and also communicates with the low-pressure side accumulator 304 through the solenoid valve 12, which is also a two-way on-off valve. Connect to the reservoir tank 16. A spring 17 on the opposite side of the hydraulic fluid chamber 14 presses the switching valve 5 to the left in the figure, that is, in a direction that makes the hydraulic fluid chamber 14 smaller. A piston hydraulic fluid chamber 18 is formed within the bore 4 in the intermediate small diameter portion of the switching valve 5 and by the bore 7 above the piston 9. This piston hydraulic oil chamber 1
8 selectively communicates with two ports 19 and 20 depending on which of the two left and right positions the switching valve 5 is in. One port 19 is returned to the high-side accumulator 204 via a pipe 21a, and the other port 20 is returned to the tank 16 via a throttle 22. A pump hydraulic oil chamber 23 formed in the bore 6 on the lower side of the plunger 8 communicates with the nozzle 10, and also communicates with the nozzle 10, and also provides low pressure via the reverse valve 24 and the above-mentioned metering solenoid valve 13, which is a two-way on-off valve. It communicates with the side accumulator 304. The input port of the control device 30 is electrically connected to various sensors (not shown),
And the output port is connected to the three solenoid valves 11, 1 mentioned above.
2 and 13 and sends control signals to them.

The fuel supply sources 2 and 3 include pumps 201 and 301, relief valves 202 and 302, and filters 203 and 30.
3 constitutes a normal constant oil pressure source.

The operation of the injectors 1a to 1f configured as described above will be described using the injector 1a in FIG. 3. In the position shown in FIG. 3, the solenoid valve 11 is closed and the solenoid valve 12 is open, so high pressure is The side fuel supply 2 is disconnected from the switching valve hydraulic fluid chamber 14 , which communicates with a reservoir tank 16 . Therefore, due to the spring 17, the switching valve 5 assumes the left position, and the port 20 is connected to the piston hydraulic oil chamber 1.
8, the fuel in this chamber 18 can be released into the reservoir tank 16. In this state,
When a signal that gives the solenoid valve 13 an opening time corresponding to the injection amount is input from the control device 30, the valve is opened for this period as shown in the figure, and the fuel from the low pressure side fuel supply source 3 flows through the reverse valve 24. It is introduced into the pump hydraulic oil chamber 23 through the pump and filled with a predetermined amount, and then the metering solenoid valve 1
3 is considered closed. At this time, the piston 9 and plunger 8 rise.

When the solenoid valve 11 is opened and the other solenoid valve 12 is closed, hydraulic pressure from the low-pressure side fuel supply source 3 acts on the switching valve operating chamber 14 via the pipe 15a, and at the same time, this chamber 14 is turned into a reservoir. It is separated from the tank 16. As a result, the switching valve 5 moves to the right in the figure against the spring 17, closing the port 20 and closing the port 1.
Let's open 9. In this way, the hydraulic pressure from the high pressure side fuel supply source 2 is transferred to the piston hydraulic oil chamber 1 via the pipe 21a.
8, and by this hydraulic pressure, the pistons 9,
Plunger 8 moves downward. At this time, the pressure in the pump chamber 23 can theoretically be adjusted to the high pressure side fuel supply source 2.
An ultra-high pressure is generated in the pump hydraulic chamber 23, which is increased to a piston-to-plunger cross-sectional area ratio of the hydraulic pressure. This ultra-high pressure fuel is prevented from flowing backward by the check valve 24, and is supplied to the nozzle 10 and injected into a combustion chamber of an internal combustion engine (not shown).

The above is the operation during normal operation, and this will be further explained with reference to the timing diagram of FIG. 4. Second
When the first electromagnetic valve 12 is closed and the first electromagnetic valve 11 is opened at timing A, the spool is moved to the right by the oil pressure, and the piston and plunger are subsequently pushed down to inject fuel. Next, at timing B, the first solenoid valve 11 is closed,
The spool that opens the second solenoid valve 12 is pushed back to the left. The second solenoid valve 12 is then closed. In this state, the third electromagnetic valve is opened from timing C and kept open until timing D, during which time the plunger and piston are pushed up and the injected fuel is introduced. What is shown in FIG. 3 is the state during this period. When the third solenoid valve is closed at timing D, timing A of the next cycle returns in that state. At this time, the injection amount is controlled by
You can see that it takes place in CD time. Therefore, in the case of partial load, the control valve opening time becomes CD' as shown by the broken line in the figure.

As can be understood from the operation of the injector 1a as described above, when each injector 1a to 1f injects fuel, the fuel pressure is suddenly released, so the pressures of the high-pressure fuel supply source 2 and the low-pressure fuel supply source 3 drop instantaneously. do. However, as in the configuration shown in FIG.
Since the pressure is accumulated to 304 and 305, it is possible to prevent an adverse effect due to a decrease in fuel pressure. In other words, in terms of the high-pressure side accumulators 204 and 205, injectors with different injection orders are divided into groups, and the injectors 1a to 205 are
A set of injectors 1d to 1f is set with a set of 1c, and an accumulator 20 is set for each group.
4,205 and are connected, each accumulator 204,20
In the case of pressure fluctuation 5, the injection order fluctuates every other time. In the case of the individual accumulators 204 and 205, since the time interval between pulsating pressures becomes longer, the previous pulsation does not affect the subsequent injection. In other words, since pulsation is prevented, stable fuel pressure can be applied to the injectors 1a to 1f, and variations in injection characteristics among the injectors 1a to 1f can be prevented.

FIG. 6 shows a conventional system in which a single accumulator 204', 304' is installed close to the fuel supply sources 2 and 3. As can be seen from the characteristic diagram in Fig. 7, this product has an accumulator 20
The time interval between the pressure fluctuations within 4' is short, and the next injection begins before the pulsation that occurred when the previous injection ended has been completely resolved, so pulsation tends to cause variations in injection characteristics. .

In addition, each accumulator 204, 205, 30
4,305 has a capacity of about 100 times the amount of fuel used in one injector.
Since the characteristics shown in the figure can be achieved, there is no need to increase the size of each accumulator 204, 205, 304, 305.

Furthermore, from the perspective of piping layout, in the case of the conventional example shown in FIG. Therefore, a large number of long pipes are required, which makes piping work troublesome and the area around the engine 100 becomes complicated.

On the other hand, in the embodiment shown in FIG. 1, since the accumulators 204, 205, 304, and 305 are relatively small,
Pipes 21a to 21f connecting each accumulator 204, 205 and 304, 305 to injectors 1a to 1f can be arranged close to f.
And 15a to 15f can be short. Pipes 21x, 21y, 15x connecting the accumulators 204, 205, 304, 305 and the fuel supply sources 2, 3,
15y is longer, but since there are fewer of them in total, piping work is easier, the area around the engine 100 is simplified, and the space required is smaller.

Note that the present invention is not limited to the embodiment shown in FIGS. 1 to 5. For example 6
In the case of a cylinder engine, an accumulator may be used for every two injectors to group the accumulators. Further, the configuration of the injector is not limited to that shown in FIG. 3, and therefore the accumulator is not limited to being used on the high pressure side and the low pressure side. Further, as the accumulator, other structures such as a bladder type, diaphragm type, and piston type can also be used.

As described above, according to the present invention, injectors with different injection orders are grouped and a single accumulator is provided for each group.
Inside each accumulator, it becomes less susceptible to the influence of injection pulsation between the injectors, and as a result, the pressure inside the accumulator becomes stable and the pressure supplied to the injector becomes stable, eliminating variations in injection characteristics and making it possible to downsize the accumulator. can. In addition, since the accumulator is placed close to the injector, the piping structure is simple.
Although a plurality of accumulators are used, there are advantages such as the space around the engine can be made smaller because the accumulators are smaller and the piping is simpler.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, in which FIG. 1 is an overall configuration diagram, FIG. 2 is a sectional view of an accumulator, and FIG. 3 is a configuration diagram of an injector.
FIG. 4 is an explanatory diagram of the operation of the injector, and FIG. 5 is a characteristic diagram showing pressure fluctuations of the accumulator. FIG. 6 is a block diagram of a conventional device, and FIG. 7 is a pressure fluctuation characteristic diagram of the accumulator. 100...engine, 1a-1f...injector, 2,3...fuel supply source, 204,205,
304, 305...Accumulator, 21a-2
1f, 21x, 21y...Piping, 15a-15
f, 15x, 15y...Piping.

Claims (1)

[Claims] 1 In a fuel injection device that distributes and injects fuel to each cylinder from a common fuel supply source using injectors provided for each cylinder, each injector is divided into multiple groups with different injection orders. A fuel injection device for a multi-cylinder internal combustion engine, characterized in that a single accumulator is provided adjacent to each group, and fuel is distributed and supplied to each injector from the fuel supply source through the accumulator.