JPH0949449A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress pulsation generated in a fuel pipe without increasing and changing a part, by irregularly changing injection timing of a fuel injection valve in one cylinder relating to injection timing of a fuel injection valve in the other cylinder in a certain specific operating condition. SOLUTION: In an ECU 18, so as to effectively induce damping of a pulsation, in an operating region of generating pulsation in a delivery pipe 10, in a spot almost in the intermediate between injection timing of the third injector 9c and injection timing interval of the fourth injector 9d, a function of transferring the injection timing of the fourth injector 9d is set. In this way, in only the fourth injector 9d, fuel is injected by irregular injection timing such as injecting fuel by an injection timing interval different from an injection timing interval of the other cylinders 1a to 1c. Thus by suppressing generating a pulsation in the delivery pipe 10 for causing a fuel injection amount decrease, an operating region for fluctuating a fuel injection amount can be effectively improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device which sequentially injects fuel at a predetermined injection cycle by means of a fuel injection valve.

[0002]

2. Description of the Related Art Some engines (internal combustion engines) mounted on automobiles employ a fuel injection device for supplying a predetermined amount of fuel at an appropriate time to perform air-fuel ratio control.

In such a fuel injection system for an engine, injectors (fuel injection valves) are provided for each cylinder, these injectors are connected to a delivery pipe, and the fuel pressure-fed to the delivery pipe is sucked into each cylinder. The structure is such that the injector sequentially injects into the manifold or the cylinder at a predetermined injection timing corresponding to.

In the fuel injection using a plurality of injectors as described above, the injectors of each cylinder independently inject fuel in a certain cycle in the order of combustion, sequential injection, and the fuel is fixed in a group divided in the order of combustion. Group injection that injects in a cycle is used.

In such a fuel injection device, pulsation occurs in the delivery pipe when the injector injects the fuel.

However, due to the influence of the pulsation generated in the delivery pipe, as shown in FIG. 10, there may be a phenomenon in which the fuel injection amount decreases when the engine is operating in a specific state.

This is because at a certain engine speed,
This is because a resonance phenomenon in which the natural frequency of the fuel piping system and the injection cycle resonate is induced in the delivery pipe, and the fuel is continuously injected at the valley of the amplitude of the pulsating pressure amplified by this resonance.

That is, in a specific engine operating region, fuel having a low fuel pressure is injected, and the fuel injection amount is reduced only in that region.

Therefore, as a countermeasure against this, Japanese Patent Publication No. 4-24
As disclosed in Japanese Patent No. 546, it has been proposed to provide a fuel pulsation damper in the delivery pipe to attenuate fuel pressure pulsation in the delivery pipe, or to increase the capacity of the delivery pipe to avoid resonance. .

[0010]

By the way, in recent years, when low cost has been called for, suppression of pulsation must be a technique which can be achieved at the lowest possible cost.

However, in the former technique, a fuel pulsation damper must be separately provided according to the delivery pipe.

In the latter technique, it is necessary to manufacture the delivery pipe according to the engine, and therefore there is a problem that the cost becomes high.

Therefore, it is conceivable to improve not in terms of hardware but in terms of software.

For example, in Japanese Unexamined Patent Publication No. 62-126241, the fuel injection timing of a cylinder having a low filling efficiency at a low load is
A technique is disclosed in which the fuel is injected earlier than the fuel injection timing of a cylinder having high filling efficiency.

However, this is a technique for suppressing the difference in filling efficiency between cylinders, not a technique for suppressing pulsation.

For this reason, there is a demand for a technique that can stabilize the fuel injection amount at low cost.

The present invention has been made in view of the above circumstances, and an object thereof is to suppress pulsation generated in the fuel pipe without increasing or changing the number of parts. To provide a fuel injection device.

[0018]

In order to achieve the above object, a fuel injection device according to a first aspect of the present invention is a fuel injection device of sequential injection, in a specific operating state,
It is to change the injection timing of the fuel injection valve of a certain cylinder irregularly with respect to the injection timing of the fuel injection valve of another cylinder.

According to this sequential injection fuel injection device, the fuel injection valve that has been injecting fuel at a predetermined injection timing for each cylinder has an injection timing of the fuel injection valve of a certain cylinder when a certain operating state is reached. Are irregularly changed with respect to the fuel injection timing of other cylinders.

Then, fuel injection into a certain cylinder is performed in a portion other than the valley of the pulsating pressure, and the amplitude of the pulsating pressure decreases.

This behavior induces a phenomenon in which pulsation is dampened and avoids resonance with the natural frequency of the fuel piping system.

That is, the behavior of decreasing the fuel injection amount is improved and the fuel injection amount can be stabilized only by improving the control aspect of changing the fuel injection timing.

In the fuel injection device according to the second aspect of the present invention, the injection timing of the fuel injection valve of a certain cylinder is shorter than the injection timing interval between the fuel injection valve of the front cylinder and the injection timing of the rear cylinder in a specific operating state. It is set to be longer than the injection timing interval with the fuel injection valve.

Even in this case, the fuel injection in a certain cylinder similarly induces a phenomenon in which the pulsation is attenuated, and resonance with the natural frequency of the fuel piping system is avoided.

In the fuel injection system according to the third aspect of the present invention, the injection timing of the fuel injection valve of a certain cylinder is approximately matched with the injection timing of the fuel injection valve of the front cylinder or the rear cylinder in a specific operating state. To change.

In this way as well, fuel injection in a certain cylinder similarly induces a phenomenon in which pulsation is attenuated, and resonance with the natural frequency of the fuel piping system is avoided.

In addition to the above object, the fuel injection device according to a fourth aspect of the present invention is the fuel injection device according to any one of the first to third aspects, in order to effectively improve the operating range in which the fuel injection amount varies. The specified operating state was set to a state in which pulsation causing a decrease in fuel injection occurred in the fuel pipe.

In addition to the above-mentioned object, the fuel injection device according to a fifth aspect of the present invention further improves the operating range more easily.
The specific operating state described in claim 4 is set based on at least information on the rotational speed and the load of the internal combustion engine.

In order to achieve the above object, a fuel injection device according to a sixth aspect of the present invention is a fuel injection device for group injection, in which a fuel injection valve of a cylinder group is set to a different injection timing in a specific operating state. It is to irregularly change the injection timing of the fuel injection valve of the cylinder group.

By doing so, the pulsation of the group injection fuel injection device is attenuated by the fuel injection of a certain cylinder group, as in the case of the sequential injection fuel injection device described in the first claim. And the resonance with the natural frequency of the fuel piping system is avoided.

In addition to the above object, the fuel injection device according to a seventh aspect of the invention has a specific operating condition according to the sixth aspect, in order to effectively improve the operating range in which the fuel injection amount varies.
The pulsation that causes a decrease in fuel injection is generated in the fuel pipe.

In addition to the above object, the fuel injection device according to the eighth aspect of the present invention further improves the operating range more easily.
The specific operating state described in claim 7 is set based on at least information on the rotational speed and the load of the internal combustion engine.

In addition to the above object, the fuel injection device according to a ninth aspect of the invention has an operating state detecting means for detecting the operating state of the internal combustion engine and a driving state detecting means for detecting the operating state of the internal combustion engine in order to easily realize pulsation suppression. By the output, the internal combustion engine, the determination means for determining whether the operating range in which pulsation occurs in the fuel pipe, and the injection timing of a cylinder or a group of cylinders when the determination means determines that the operating range is within the operating range The control means for changing the injection timing so as to be irregular with respect to the injection timing of other cylinders or cylinder groups is adopted.

According to this fuel injection device, when the determining means determines that the operating range is where pulsation occurs in the fuel pipe during operation of the internal combustion engine, the injection timing of a certain cylinder (in the case of sequential injection) or a certain cylinder group. The injection timing (in case of group injection) is changed so as to be irregular with respect to other injection timings.

As a result, similarly to the above, the phenomenon in which the pulsation is attenuated is induced, and resonance with the natural frequency of the fuel piping system is avoided.

In addition to the above object, the fuel injection device according to a tenth aspect of the invention has a driving state detecting means according to the ninth aspect, in order to easily realize the pulsation suppression.
An engine speed detecting means for detecting the engine speed of the internal combustion engine, and a pressure detecting means for detecting the pressure in the intake manifold are provided, and the determining means is represented by the engine speed and the manifold pressure. An operating state map in which a region where the fuel injection amount is reduced is set, and a determination function which determines whether the detected engine speed and manifold pressure are in the region where the fuel injection amount is reduced are configured. The control means is configured to have a change function for randomly changing the injection timing of a certain cylinder or cylinder group with respect to another injection timing when it is determined that the control means is in a region where the fuel injection amount decreases. There is something I did.

In addition to the above object, the fuel injection device according to an eleventh aspect of the present invention is the fuel injection device according to the ninth or tenth aspect, in order to effectively induce pulsation damping. The point approximately midway between the above is set in the control means as the injection timing for change.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the first embodiment shown in FIGS.

FIG. 1 shows an MPI (multipoint injection) type multi-cylinder engine (internal combustion engine), for example, 4
Showing the structure of a cycle, in-line 4-cylinder gasoline engine,
In the figure, 1 is an engine body.

The engine body 1 is provided with four cylinders designated by reference numerals 1a to 1d. In addition, each cylinder 1a-1
In d, a valve mechanism and a spark plug (neither is shown) are provided for each cylinder.

The ignition order of the spark plugs is, for example, No. 1-3.
-It is set to be performed in the order of 4-2 cylinder,
According to the ignition sequence, four strokes of an intake stroke, a compression stroke, an explosion stroke, and an exhaust stroke are repeatedly performed in each cylinder 1a-1b.

On both sides of the engine body 1, an exhaust manifold 2 is connected to each cylinder on one side of the engine body 1 where an exhaust port (not shown) is provided.

An intake manifold 3 is provided on the other side of the engine body 1 where the remaining intake port (not shown) is provided.

The intake manifold 3 has a collecting passage 5 connected to the surge tank 4 on the upstream side, and branch passages 6a to 6d branched from the collecting passage 5 for each cylinder on the downstream side.

The branch passages 6a to 6d are opened to the side of the engine body 1 and connected to the intake ports.
A throttle valve 7 is provided in the collecting passage 5, for example.

The intake manifold 3 is provided with, for example, a sequential type fuel injection device 8.

Explaining the fuel injection device 8, 9a to 9d
Are first to fourth injectors (fuel injection valves) arranged for each cylinder.

The injection portion of each of the first to fourth injectors 9a to 9d is provided in each of the branch passages 6a to 6d, for example, the engine body 1.
It is connected to the part near.

The first to fourth injectors 9a to 9d are also provided.
The base part of the delivery pipe 10 is closed on one side.
Connected to each other. This base is the fuel pipe 1
1, it is connected to the discharge portion of a fuel pump 14 provided in the fuel tank 13 via the fuel filter 12.

A return pipe 16 having a pressure regulator 15 interposed is connected to the fuel filter 12, and the fuel 17 in the fuel tank 14 is supplied to the fuel pipe 12 at a constant fuel pressure through the delivery pipe 10. The fourth injectors 9a to 9d can be supplied to the cylinders 1a to 1d.

Each of the first to fourth injectors 9a-9d is
It is connected to the ECU 18 (which is composed of a microcomputer and its peripheral devices and corresponds to control means).

The ECU 18 includes an engine speed sensor 19 (rotation speed detecting means) for detecting an engine speed, a crank angle sensor 20, a throttle opening sensor 21 for detecting a throttle opening, and a sensor for detecting an intake air amount ( A control device necessary for calculating the fuel injection amount and determining the injection timing (such as not shown) is connected.

Further, the ECU 18 has a function of obtaining a fuel injection amount according to information from various sensors, and opens the first to fourth injectors 9a to 9d so that the fuel injection amount is injected in a predetermined cycle in the order of combustion. The function to operate the valve is set.

As a result, the first to fourth injectors 9a
9d, the fuel 17 can be injected independently at a fixed cycle in the order of combustion as shown in FIG. 4 (a) (sequential injection).

In addition to the function of performing such sequential injection, the ECU 18
A function is set to make the injection timings of some of the first to fourth injectors 9a to 9d irregular.

To explain this function, the ECU 18
A pressure sensor 22 (pressure detecting means) for detecting the pressure in the intake manifold 3, for example, is connected to the engine to obtain load information of the engine.

The ECU 18 detects the operating state of the engine from the manifold pressure (engine load) from the pressure sensor 22 and the engine speed from the engine speed sensor 19 (operating state detecting means). .

Further, in the RAM (not shown) of the ECU 18, an operating condition map represented by the engine speed and the intake manifold pressure as shown in FIG. 2 is set in advance.

This operation state map shows the operation range β (certain operation state) in which a pulsation that causes a decrease in the fuel injection amount occurs in the delivery pipe 10 obtained by experiments and the other fuel injection amounts do not change. It is represented together with the operating range α.

Further, the ECU 18 includes various sensors 19,
A function is provided to determine whether the engine speed and the manifold pressure detected at 22 are within the operating range β of the operating state map, and the operating state in which the fuel injection amount decreases is specified.

In addition, when the ECU 18 determines that it is within the operating range β, the injection timing of the fourth injector 9d in a certain cylinder, for example, the cylinder 1d (injection timing of the cylinder 1d).
The third injector 9c, as shown in FIG. 4 (b).
Is set to the injection timing (the injection timing of the previous cylinder 1c) side.

More specifically, the ECU 18 determines that the injection timing of the third injector 9c and the injection timing interval of the fourth injector 9d are substantially in the middle when the operation range β is set so that the damping of the pulsation is effectively induced. At the point of 4th injector 9d
The function to shift the injection timing of is set. FIG.
In (b), reference sign P indicates the changed injection timing.

As a result, only the fourth injector 9d is injected at an irregular injection timing in which fuel is injected at injection timing intervals B and C different from the injection timing interval A of the other cylinders 1a to 1c. Is done.

The changed injection timing P of the fourth injector 9d is shorter than the injection timing interval A between the third cylinder 9c of the front cylinder 1c and the second cylinder 9b of the rear cylinder 1b as shown in FIG. 4 (b). It is also a portion that is longer than the injection timing interval A with 9b, and is also a portion that substantially matches the injection timing of the third injector 9c of the front cylinder 1c.

By making the injection timing of the fourth injector 9d irregular only in the operation region β, the pulsation in the delivery pipe 10 which causes the decrease in the fuel injection amount is suppressed, and the fuel injection amount fluctuates. The operating range β is effectively improved.

A flowchart of this control is shown in FIG.

Before explaining this flowchart, the operation of the engine will be described.

That is, when the engine is started and the operation is started, the fuel pump 14 operates and the fuel in the fuel tank 13 is pumped to the delivery pipe 10 at a constant fuel pressure.

On the other hand, the valve operating mechanism of each cylinder 1a-1d receives the rotational force transmitted from the crankshaft and receives each cylinder 1a.
The intake valve and the exhaust valve of 1d are driven in the order of the cylinder 1-3-4-2.

At this time, the ECU 18 obtains the required fuel injection amount from the intake air amount, the engine speed, the throttle opening, etc. obtained from various sensors.

Further, the ECU 18 uses the obtained crank angle to sequentially inject the injectors 9a to 9d at predetermined injection timings in the order of cylinders 1-3-4-2 shown in FIG. 4 (a).
An injection pulse is output according to the fuel injection amount.

As a result, the fuel 17 in the delivery pipe 10 is injected into each of the injectors 9a to 9a at a predetermined fuel injection timing.
9d is sequentially supplied to each cylinder 1a to 1d in the intake stroke.

Then, each spark plug is connected to each cylinder 1a-1
In the compression stroke of d, the cylinders 1-3a-1-2 are operated in this order, and the cylinders 1a to 1d are ignited.

After that, each of the cylinders 1a to 1d goes through the exhaust stroke and then reaches the intake stroke again.

The engine is operating by repeating such a cycle.

Next, the pulsation suppression control performed by the ECU 18 will be described.

During operation of the engine as described above, the ECU 18
Reads the engine speed output from the engine speed sensor 19 and the manifold pressure output from the pressure sensor 22 as in step S1.

Then, in step S2, the map of the operating condition shown in FIG. 2 is read, and then the process proceeds to step S3.

In step S3, it is determined whether the engine operating condition is in the operating range β. Specifically, EC
U18 determines whether the engine speed and the manifold pressure during operation correspond to the region β.

At this time, if it is determined that the operation range β is not set, that is, the operation range α is set, the ECU 18 determines that the pulsation that causes a problematic decrease in the fuel injection amount does not occur in the delivery pipe 10. Then, the process proceeds to step S4.

As a result, the ECU 18 regularly outputs the injection pulse, and as described above, each injector 9
a to 9d at a predetermined injection timing (constant injection timing interval A)
Then, operate it regularly and sequentially.

At this time, it is assumed that the operating state of the engine is changed from the operating range α of the operating state map to the operating state corresponding to the operating range β.

Then, the ECU 18 is in the operating range β where the injection cycle and the natural frequency of the fuel piping system resonate in step S3 from the engine speed from the engine speed sensor 19 and the manifold pressure from the pressure sensor 22. Then, the process proceeds to step S5.

In step S5, the operation of this engine is continued for a predetermined time.

Depending on whether or not this predetermined time has elapsed, E
The CU 18 confirms whether or not the pulsation generated in the delivery pipe 10 due to the fuel injection has a stable behavior.

Here, looking at the behavior of the fuel injection at this time, as shown in FIG.
9d injects the fuel 17 in the valley of the pulsating pressure whose amplitude is increased by the resonance between the fuel injection cycle (constant injection timing interval A) and the natural frequency of the fuel piping system.

That is, in the operating state of the engine corresponding to the operating range β, the fuel 17 having a low fuel pressure is continuously injected (fuel injection amount decrease).

After a certain period of time, when step S6 is reached,
As shown in FIG. 4 (b), the ECU 18 shifts only the fourth injector 9d of the cylinder 1d to an injection timing P that is substantially in the middle of the injection timing interval A with the third injector 9c.

As a result, the injectors 9a-9 which have injected fuel at the predetermined injection timing A for each of the cylinders 1a-1d.
When d is within the operating range β (a certain operating state), only the injection timing of the fourth injector 9d is different from the other cylinders 1a to 1c as indicated by the chain double-dashed line and arrow S in FIG. 4 (b).
It is irregularly changed with respect to the fuel injection timing of 1c.

Then, the fuel injection from the fourth injector 9d is performed in a portion other than the valley of the pulsating pressure, and the amplitude of the pulsating pressure decreases.

This behavior induces a phenomenon in which pulsation is attenuated in the delivery pipe 10 and avoids resonance with the natural frequency of the fuel piping system.

That is, the behavior that the fuel injection amount decreases is improved, and the stable injection amount is secured in the operating range β as in the other operating ranges α.

Therefore, it is possible to improve the decrease in the fuel injection amount that has occurred in a specific operating range of a certain engine only by changing the control that changes the fuel injection timing without increasing or changing the parts. You can

Structurally, this means that the device controlling the engine can be used as it is to eliminate the decrease in the fuel injection amount due to the pulsation, and the cost is considerably low.

Moreover, pulsation can be easily suppressed. In particular, since the specific operating state is set by the information on the engine speed and the load (manifold pressure) of the engine, it is possible to easily improve the decrease in the fuel injection amount that has occurred in the specific operating range.

In addition, the pulsating sound of the fuel 17 is improved, so that the noise can be reduced.

In particular, the pulsation amplitude tends to be large in FIG.
Fuel pump 14 and delivery pipe 10 as shown in FIG.
This is suitable for the fuel injection device 8 in which the fuel 17 is returned from between.

When the operating state of the engine returns to the operating range α, the ECU 18 proceeds from step S3 to step S4 and again causes the first to fourth injectors 9a to 9d to have a predetermined injection timing (constant injection timing interval A ) To inject the fuel 17.

Of course, if the operating state of the engine enters the operating range β again, irregular fuel injection is performed with the injection timing of the fourth injector 9d deviated.

However, due to the processing of step S5, switching at the boundary between the operating range α and the operating range β does not occur frequently.

Although the fourth injector 9d is shifted to the front cylinder side in the first embodiment, the same effect can be obtained even if the fourth injector 9d is shifted to the rear cylinder side.

In the first embodiment, the fourth injector 9 is used.
Although the injection timing of d is shifted, the injection timing of other injectors may be shifted. Needless to say, the injection timings of a plurality of injectors, for example, two injectors instead of one may be shifted.

5 to 7 show a second embodiment of the present invention.

The second embodiment shows an example in which the fuel injection device 8 adopts a group injection in which the fuel 17 is injected at a constant cycle in groups divided in the order of combustion.

Specifically, in the fuel injection device 8 of the second embodiment, for example, as shown in FIG. 7A, the second injector 9b and the fourth injector 9d, the first injector 9a and the third injector 9c. Each form a group and injects the fuel 17 at a predetermined injection timing (constant injection timing interval D).

In the second embodiment, the injection timing of a specific cylinder group of the fuel injection device 8, for example, the injection timings of the first and third injectors 9a and 9c are set to a specific operating range β. At this time, the injection timings of other cylinder groups are irregular.

That is, when it is determined by the ECU 18 that it is within the driving range β of the driving state map shown in FIG.
Injection timing of the first and third injectors 9a and 9c (cylinder 1
(a, 1c injection timing), as indicated by the alternate long and two short dashes line and arrow S in FIG.
It is set to shift to the injection timing of 9d (the injection timing of the previous cylinder group).

Specifically, when it is determined that the vehicle is in the operating range β, the ECU 18 determines that the injection timings of the second and fourth injectors 9b and 9d and the injection timing intervals of the first and third injectors 9a and 9c are substantially in the middle. , The first and third injectors 9a, 9
A function for changing the injection timing of c is set. The injection timing changed in this embodiment is also indicated by a symbol P.

Of course, the first and third injectors 9a, 9a,
The changed injection timing P of 9c is the same as in the first embodiment, as shown in FIG.
It is an interval E shorter than the injection timing interval D with the injectors 9b and 9d, an interval F longer than the injection timing interval D for the rear cylinder group, and a portion that substantially matches the injection timing for the front cylinder group.

The fuel injection device 8 for such group injection
However, according to the control shown in the flowchart of FIG. 6, similarly to the case of the fuel injection device 8 of the sequential injection, the phenomenon in which the pulsation is attenuated is induced, and the resonance with the natural frequency of the fuel piping system is avoided. .

As a result, as in the case of the sequential fuel injection device 8, the operating range β is changed to another operating range α.
A stable injection amount similar to that is secured.

That is, the group injection fuel injection device 8
Also has the same effect. In particular, it is suitable for the group injection fuel injection device 8 in which the pulsation amplitude tends to increase.

5 to 7, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

Further, the fuel pump 14 and the delivery pipe 1
Not only the fuel injection device 8 configured to return the fuel 17 from between 0 and 0, but the delivery pipe 10 having both open ends as in the third embodiment shown in FIG. 8 is used, and one end of the delivery pipe 10 is used. The fuel injection device 8 in which the fuel pump 14 is connected to the other end and the pressure regulator 15 is provided at the other end to return the fuel 17 from the end of the delivery pipe is also capable of varying the capacity as in the fourth embodiment shown in FIG. The fuel pump 10 is used, and the pressure sensor 25 for detecting the fuel pressure of the delivery pipe 10 is provided. According to the information of the pressure sensor 25, the capacity of the fuel pump 10 is controlled so that the fuel pressure in the delivery pipe 10 becomes a predetermined pressure. , A fuel injection device 8 for injecting fuel from each of the injectors 9a to 9d, and a fuel in which a pressure accumulator is combined with the fuel injection device 8. Even in the injection device (not shown), if the control of changing the fuel injection timing is adopted as in the first and second embodiments, the pulsation that causes the decrease in the fuel injection amount as described in the previous embodiment is adopted. Can be suppressed.

Needless to say, the present invention may be applied to a fuel injection device in which fuel is directly injected into a cylinder instead of the intake manifold.

Further, the load information of the engine is directly detected from the pressure in the intake manifold for the setting of the specific operating state, but the present invention is not limited to this, and other means for indirectly detecting the load information of the engine is used. May be used.

In addition, although the specific operating state is set by the engine speed and engine load information, it is not limited to this and may be set by using other information as well, in short, at least the engine speed. By the information of engine load,
It is only necessary to set a specific operating state.

Although the present invention is applied to a 4-cylinder gasoline engine, other multi-cylinder gasoline engines may be used. It may also be applied to other multi-cylinder engines such as other diesel engines.

[0119]

As described above, according to the first, second and third aspects of the present invention, a certain operating condition is maintained without increasing or changing the parts. Only by changing the injection timing of the cylinder, the pulsation generated in the fuel pipe can be attenuated and the resonance with the natural frequency of the fuel pipe system can be avoided.

As a result, the pulsation generated in the fuel pipe is suppressed, the behavior of the decrease in the fuel injection amount caused by the pulsation is improved, and the fuel injection amount can be stabilized.

Further, the pulsating sound is suppressed and the noise can be reduced.

According to the invention described in claim 4, in addition to the effect of the invention of claim 1, claim 2 or claim 3, there is an effect that the operating range in which the fuel injection amount fluctuates can be effectively improved. .

According to the invention of claim 5, claim 4
In addition to the effects of the invention described above, the operating range can be improved more easily.

According to the invention described in claim 6, even in the fuel injection device for group injection, the injection timing of a certain cylinder group is changed in a certain specific operating state without increasing or changing the number of parts. The pulsation generated in the fuel pipe can be attenuated only by the control so that resonance with the natural frequency of the fuel pipe system can be avoided.

As a result, similar to the effect of the invention of claim 1,
The pulsation generated in the fuel pipe is suppressed, the behavior of the fuel injection amount decrease caused by the pulsation is improved, and the fuel injection amount can be stabilized.

According to the invention of claim 7, claim 6
In addition to the effect of the present invention, since the injection timing of a certain cylinder is changed based on the information on the rotational speed of the internal combustion engine and the manifold pressure, it is possible to effectively improve the operating range in which the fuel injection amount varies.

According to the invention of claim 8, claim 6
In addition to the effects of the invention described above, the operating range can be improved more easily.

According to the ninth aspect of the invention, in addition to the effects of the first, second and third aspects of the invention, the pulsation can be easily suppressed even in the fuel injection system of sequential injection or group injection. There is an effect that can be made.

According to the invention of claim 10, in addition to the effect of the invention of claim 9, the structure is such that the injection timing of a certain cylinder or a certain cylinder group is changed based on the information on the number of revolutions of the internal combustion engine and the manifold pressure. The effect that the pulsation can be suppressed more easily is achieved.

According to the invention of claim 11, in addition to the effect of the invention of claim 9 or 10, there is an effect that damping of pulsation of the fuel piping system can be effectively induced.

[Brief description of drawings]

FIG. 1 is a view for explaining a sequential injection fuel injection device according to an embodiment of the first invention of the present invention.

FIG. 2 is a diagram showing a map used for changing an injection timing of a specific cylinder.

FIG. 3 is a flowchart for explaining control for changing the injection timing of a cylinder having a certain characteristic in a certain operating range.

FIG. 4A is a diagram for explaining the injection cycle of each cylinder together with the pulsation occurring in the fuel piping system. (B) is
The diagram for explaining the behavior in which the injection cycle becomes irregular due to the deviation of the injection timing of a certain cylinder and the pulsation is damped.

FIG. 5 is a diagram for explaining a group injection fuel injection device according to a second embodiment of the present invention.

FIG. 6 is a flowchart for explaining control for changing the injection timing of a cylinder group having a certain characteristic in a certain operating range.

FIG. 7A is a diagram for explaining the injection cycle of each cylinder group together with the pulsation occurring in the fuel piping system. (B)
FIG. 6 is a diagram for explaining a behavior in which the pulsation is attenuated due to the irregular injection cycle due to the deviation of the injection timing of a certain cylinder group.

FIG. 8 is a diagram for explaining a fuel injection device according to a third embodiment of the present invention, which has a pressure regulator at the tip of a delivery pipe and returns fuel.

FIG. 9 is a diagram for explaining a fuel injection device that is a fourth embodiment of the present invention and that varies pump capacity according to the output of a pressure sensor.

FIG. 10 is a diagram showing that a pulsation occurring in the fuel piping system causes a behavior of reducing the fuel injection amount in a specific engine operating range.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine main body 1a-1d ... Cylinder 3 ... Intake manifold 6a-6d ... Branch passage 8 ... Fuel injection device 9a-9d ... 1st-4th injector (fuel injection valve) 10 ... Delivery pipe 11 ... Fuel pipe 12 ... Fuel Filter 13 ... Fuel tank 14 ... Fuel pump 15 ... Pressure regulator 16 ... Return pipe 18 ... ECU (control means, determination means) 19, 22 ... Engine speed sensor, pressure sensor (operating state detection means) P ... Changed injection timing .

Claims (11)

[Claims] 1. A fuel injection device for sequentially injecting fuel at a predetermined injection timing from a fuel injection valve provided for each cylinder, in a certain operating state, the injection timing of the fuel injection valve of a certain cylinder. Is irregularly changed with respect to the injection timing of the fuel injection valve of another cylinder. 2. A fuel injection device for sequentially injecting fuel at a predetermined injection timing from a fuel injection valve provided for each cylinder, and in a certain operating state, the injection timing of the fuel injection valve of a certain cylinder. Is shorter than the injection timing interval with the fuel injection valve of the front cylinder,
A fuel injection device characterized by being set to be longer than an injection timing interval with a fuel injection valve of a rear cylinder. 3. A fuel injection device for sequentially injecting fuel at a predetermined injection timing from a fuel injection valve provided for each cylinder, and in a certain operating state, the injection timing of the fuel injection valve of a certain cylinder. Of the fuel injection valve of the front cylinder or the rear cylinder so as to be substantially matched with the injection timing of the fuel injection valve. 4. The fuel injection device according to any one of claims 1 to 3, wherein the certain operating state is a state in which pulsation causing a decrease in fuel injection occurs in the fuel pipe. A fuel injection device characterized by: 5. The fuel injection device according to claim 4, wherein the specific operating state is set based on at least information on the rotational speed and the load of the internal combustion engine. 6. A fuel injection device for sequentially injecting fuel from a fuel injection valve at a predetermined injection timing for each certain cylinder group, wherein the injection timing of the fuel injection valve of the certain cylinder group is set in a certain operating state. , A fuel injection device characterized by irregularly changing the injection timing of the fuel injection valve of another cylinder group. 7. The fuel injection device according to claim 6, wherein the certain operating state is a state in which pulsation causing a decrease in fuel injection occurs in the fuel pipe. 8. The fuel injection device according to claim 7, wherein the specific operating state is set based on at least information on the rotational speed and load of the internal combustion engine. 9. A fuel injection valve provided for each cylinder,
In a fuel injection device that sequentially injects fuel independently or in groups at a predetermined injection timing, an operating state detecting unit that detects an operating state of the internal combustion engine, and the output of the operating state detecting unit causes the internal combustion engine to
Determining means for determining whether the fuel pipe is in an operating range where pulsation occurs, and when the determining means determines that the operating range is within, the injection timing of a cylinder or a cylinder group is set to another cylinder or cylinders. A fuel injection device comprising: a control unit that changes the injection timing so as to be irregular with respect to the injection timing of the group. 10. The fuel injection device according to claim 9, wherein the operating state detecting means includes an engine rotational speed detecting means for detecting the rotational speed of the internal combustion engine and a pressure detecting means for detecting the pressure in the intake manifold. The determination means has an operating state map in which an area where the fuel injection amount is reduced is represented by the internal combustion engine speed and the manifold pressure, and the detected engine speed and manifold pressure are the fuel injection amount. When it is determined that the fuel injection amount is within the region where the fuel injection amount is reduced, the control means determines the injection timing of a certain cylinder or a group of cylinders for other injections. A fuel injection device having a changing function for changing the timing irregularly. 11. The fuel injection device according to claim 9 or 10, wherein the control means sets a point approximately midway between the injection timing intervals with respect to the preceding cylinder as the injection timing for change. A fuel injection device characterized by: