JP2000274330A - Fuel injection valve of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To concentrate the fuel near the ignition plug while securing the setting freedom of the injection timing, and to allow to form a mixture gas with a high stratified level, in the stratified combustion of a direct cylinder injection type spark ignition engine. SOLUTION: A passage area converting member 1 is provided, laminating on a fuel rotation member 8 in which fuel rotation passages 9a and 9b are formed, and the inlet part of a fuel route 10 formed around the fuel rotation member 8 is made possible to throttle by rotating the passage area converting member 11 around the axis of a valve seat. On the other hand, the rotating position of the passage area converting member 11 (the fuel passage area) is controlled depending on the engine load and the engine rotation speed, and the injection rate of a fuel injection valve is controlled to make the injection pulse width converted to the crank angle, almost constant, regardless of the engine load and the engine rotation speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve for an internal combustion engine, and more particularly, to a fuel injection valve having a fuel swirling member for giving a swirling force to fuel, and particularly suitable for a direct in-cylinder injection spark ignition engine.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection valve for an internal combustion engine, there has been a fuel injection valve disclosed in Japanese Patent Application Laid-Open No. 7-174058.

[0003] In this apparatus, a fuel swirling element for giving a swirling force to fuel is provided upstream of an injection hole of a fuel injection valve.
The radial fuel passage formed in the fuel swirling element is divided into a large passage and a small passage, and the swirl fuel generated by passing through the small passage and the swirl fuel generated by passing through the large passage. The fuel is divided into non-swirl fuel, and the swirl fuel is included and injected by the non-swirl fuel, so that a spray having a narrow spray angle and good atomization can be injected.

[0004]

However, during stratified charge combustion in a direct in-cylinder injection spark ignition engine, it is required not only to atomize the fuel but also to concentrate the fuel near the spark plug at the time of ignition. In a fuel injection valve configured to diverge into swirling fuel and non-swirl fuel, as in the fuel injection valve, the non-swirl fuel increases the reach of spray,
There is a problem that the concentration of fuel around the spark plug may be reduced.

It is desired that the injection timing and ignition timing at which combustion stability is obtained during stratified combustion have as high a degree of freedom as possible irrespective of rotational conditions from the viewpoint of controllability. At the time of rotation, the angle period during which fuel stays around the spark plug becomes shorter, so it is required to control the injection timing and the ignition timing within a narrow range.
Although the angle period during which the fuel stays around the spark plug becomes longer, there is a problem that the gas flow depending on the rotation speed of the engine becomes stronger and the degree of stratification of the air-fuel mixture decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and when used in a direct cylinder injection type spark ignition engine, combustion stability in a wide range irrespective of rotation or load in a stratified combustion state. And to provide a fuel injection valve which does not reduce the fuel concentration around the spark plug even when the spray characteristics are changed to ensure the combustion stability. .

[0007]

According to a first aspect of the present invention, a fuel swirl passage extending substantially in the radial direction of a valve seat is provided, and the fuel swirl passage provides a swirling force to the fuel. A fuel injection valve having a swirl member, an injection rate changing means for changing an injection rate by changing a fuel passage area on an upstream side of the fuel swivel member, and the injection rate change means being adapted to an operating condition of the engine. And an injection rate control means for controlling the injection rate in accordance with the control.

According to this configuration, the fuel is atomized by applying a swirling force to the fuel, while the injection rate can be changed by reducing the area of the fuel passage upstream of the fuel swirling member. The injection rate is the injection amount per unit time, and if the injection rate is different, the injection pulse width (opening time of the fuel injection valve) corresponding to the required injection amount will change,
It becomes possible to adjust the injection pulse width in terms of crank angle by controlling the injection rate.

In the invention according to claim 2, the injection rate changing means changes the fuel passage area according to the rotational position of a passage area changing member which is driven to rotate around the axis of the valve seat.

According to this structure, the passage area changing member is rotated around the axis of the valve seat, so that the overlapping area between the fuel passage extending in the axial direction of the valve seat and the passage area changing member changes. As a result, the area of the fuel passage changes.

According to the third aspect of the present invention, the passage area changing member has a fuel swirl passage extending substantially in the radial direction of the valve seat to apply a swirling force to fuel, and is provided in the fuel swirl member. By changing the relative angle between the fuel swirl passage provided and the fuel swirl passage provided in the passage area changing member, the fuel swirl component is changed simultaneously with the change of the fuel passage area.

According to such a configuration, the passage area changing member is provided with the fuel swirl passage extending substantially in the radial direction of the valve seat and applying a swirl force to the fuel, similarly to the fuel swirl member. Since the passage area changing member is driven to rotate around the axis of the valve seat to change the fuel passage area, the angular position of the fuel swirl passage provided in the passage area changing member is fixed to the fuel of the fuel swirl member. It changes with respect to the swirl path, and the change in the relative angular position changes the swirl component of the fuel injected from the fuel injection valve. Therefore, the swirl component changes at the same time as the fuel passage area (injection rate) changes.

[0014] In the invention described in claim 4, the injection rate changing means changes the fuel passage area according to the position of the passage area changing member which is displaced in the axial direction of the valve seat.
According to this configuration, by displacing the passage area changing member in the axial direction of the valve seat, the relative distance in the axial direction between the passage area changing member forming the fuel passage and the opposing member (for example, the fuel swirling member) changes. Thus, the area of the fuel passage changes.

According to the invention described in claim 5, the passage area changing member is constituted by a laminated piezoelectric element. According to this configuration, by controlling the application of a voltage to the multilayer piezoelectric element, the multilayer piezoelectric element expands and contracts.
By fixing one end of the laminated piezoelectric element, the position of the other end is displaced in the axial direction of the valve seat, and the relative distance between the other end and the opposing member is changed, thereby reducing the fuel passage area. Change.

In the invention according to claim 6, the injection rate control means controls the injection rate change means in accordance with the rotation speed of the engine. According to this configuration, the rotation speed of the engine is information indicating the rotation angle per unit time,
For example, if the injection rate is controlled to be higher as the engine rotation speed is higher, it is possible to perform control to substantially equalize the crank angle conversion injection period for the same required injection amount regardless of the rotation speed. Further, if the injection rate is changed in accordance with the required injection amount (engine load) together with the engine rotation speed, it becomes possible to maintain the injection period in terms of crank angle substantially constant.

In the invention according to claim 7, the injection rate control means changes the injection rate by the injection rate changing means from when the injection pulse width is determined to when the injection based on the injection pulse width ends. The configuration is forbidden in between.

According to this configuration, after the injection pulse width (opening time of the injection valve) is determined based on the injection rate at that time, during the period when the injection with the determined injection pulse width is completed, Even if there is a request to change the injection rate, the change in the injection rate is reflected from the next injection without changing the actual injection rate in response to the request to change the injection rate. If the injection is performed at an injection rate different from the injection rate at the time when the injection pulse width is determined, the injection pulse width is not changed, so that the actual injection amount may be excessive or deficient. (Valve opening time) is maintained, and the change of the injection rate is postponed from the next time.

[0018] In the invention according to claim 8, the injection rate control means causes the injection rate to be changed by the injection rate changing means during fuel injection. According to this configuration, when the fuel injection is not being performed by the fuel injection valve, the fuel passage area is maintained at the reference area (for example, the maximum area, the maximum injection rate), and the required injection rate is obtained when the fuel is actually injected. Thus, the fuel passage area is changed from the reference area.

According to the ninth aspect of the present invention, the injection rate control means controls the ratio of a period in which the injection rate is reduced before the injection end timing to perform the injection so that the average injection rate of the fuel injection valve is reduced. It was configured to control.

According to this configuration, when the fuel injection is not being performed by the fuel injection valve, the fuel passage area is maintained at the reference area (for example, the maximum area) so that the required injection rate is obtained when the fuel injection is actually performed. Rather than maintaining the required injection rate during the injection period, for example, by controlling the ratio of the period of control to the maximum passage area and the period of control to the minimum passage area during the injection period, the average In the method, the injection rate is controlled to an intermediate value between the injection rate corresponding to the maximum passage area and the injection rate corresponding to the minimum passage area. In addition, when decreasing the injection rate, the injection rate is decreased during a period in which the injection end time is ended, and the injection is started at a high injection rate at the injection start time. The injection rate is reduced only for a period corresponding to the request for reducing the fuel injection, and the fuel is injected until the injection end timing.

[0021]

According to the first aspect of the present invention, by controlling the injection rate to an appropriate value for each operating state, the reaching distance of the fuel spray is changed particularly at the time of stratified charge combustion in a direct cylinder injection type spark ignition engine. Without this, it is easy to secure the residence time of the fuel and the stratification of the air-fuel mixture in the vicinity of the spark plug, increasing the degree of freedom of the injection timing, and improving the combustion stability during stratified combustion. effective.

According to the second aspect of the present invention, by rotating the passage area changing member about the axis, there is an effect that the fuel passage area can be changed by a mechanism that is compactly housed in the main body of the fuel injection valve.

According to the third aspect of the present invention, the swirl component can be changed at the same time as the injection rate is changed. For example, the spray rate is increased in a high rotation region where gas flow is strong, and the non-swirl component is increased to increase the spray rate. There is an effect that the angle can be narrowed and the fuel can be concentrated near the ignition plug.

According to the invention described in claim 4, there is an effect that the fuel passage area can be easily changed by displacing the passage area changing member in the axial direction. According to the fifth aspect of the invention, there is an effect that the fuel passage area can be changed with good response.

According to the sixth aspect of the present invention, the injection rate is increased as the engine rotational speed increases, so that the injection period in terms of crank angle is substantially equalized regardless of the rotational speed for the same required injection amount. Can be performed, and there is an effect that a period of stay of fuel near the spark plug can be secured.

According to the seventh aspect of the present invention, since the change of the injection rate to which the injection pulse width does not correspond is prohibited, the required injection amount can be accurately injected while changing the injection rate. .

According to the eighth aspect of the invention, the injection is always performed at a high injection rate at the start of the injection, which greatly affects the spray shape, and the required injection rate can be reduced during the injection. There is an effect that the injection rate can be changed without changing the shape.

According to the ninth aspect of the present invention, even if the resolution in the change control of the fuel passage area is low, by controlling the time ratio for each different injection rate during the injection period, the average injection rate can be finely adjusted. The effect is that the rate can be controlled.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 are longitudinal sectional views showing a fuel injection valve of an internal combustion engine according to an embodiment. An injection hole 3 is formed at the tip of a cylindrical main body 2 of a fuel injection valve 1 coaxially with the main body 2. A mortar-shaped valve seat 4 centering on the injection hole 3 is formed on the inner wall of the main body 2 on the upstream side of the injection hole 3.

A needle valve 5 is provided in the main body 2 so as to be movable in the axial direction.
The needle valve 5 is closed when the distal end of the needle valve 5 is seated on the valve seat 4. An electromagnet 6 is fixed in the main body 2 on the base end side of the needle valve 5.
The needle valve 5 urged in the valve closing direction by the electromagnet 6
By lifting from the valve seat 4 by the magnetic attraction force of
The valve is opened.

On the upstream side of the valve seat 4, a through hole 8 a is formed in a plate shape having a fan-shaped portion fitted to the inner peripheral wall of the main body 2 at four corners, and the needle valve 5 is inserted. The fuel swirling member 8 to be opened is fitted and fixed to the inner peripheral wall of the main body 2 so as to abut against the inner wall on the distal end side of the main body 2.

A pair of fuel swirling passages 9a and 9b are formed in the end face of the fuel swirling member 8 on the tip end side of the main body 2 so as to be parallel to each other and offset with respect to the axis of the needle valve 5. The valve seat 4 is formed in a substantially radial direction so as to communicate with the peripheral portion.

The pair of fuel swirling passages 9a and 9b face a fuel passage 10 formed between the inner peripheral wall of the main body 2 and the outer peripheral wall of the fuel swirling member 8, and are introduced into the main body 2 from the base end side. The fuel thus introduced is introduced into the pair of fuel swirl passages 9a and 9b via the fuel passage 10 and the pair of fuel swirl passages 9a and 9b.
The fuel given the turning force at a and 9b is injected from the injection hole 3 with the valve opened.

A passage area changing member 11 constituting the injection rate changing means is provided so as to overlap the fuel swirling member 8. The passage area changing member 11 is formed in substantially the same shape as the fuel swirling member 8, but has a structure in which a fuel swirl passage corresponding to the fuel swirl passages 9a and 9b is not formed. The passage area changing member 11 is provided so as to be able to rotate around the axis of the main body 2 while slidingly contacting the end face of the fuel swirling member 8 and the inner peripheral wall of the main body 2.

Here, the stopper 13 protruding from the inner peripheral wall of the main body 2 is provided in the concave portion 12 formed on the outer peripheral wall of the passage area changing member 11, so that the stopper 13 is moved in the circumferential direction of the concave portion 12. The passage area changing member 11 is configured to be rotatable within an angular range from a position in contact with one end to a position in contact with the other end.

A compression spring 14 is interposed between the stopper 13 and one end of the recess 12 in the circumferential direction.
1 is urged clockwise in FIG. 2 so as to be held at the initial position (the position in FIG. 2) rotated clockwise most in FIG. 2.

As an actuator for rotating the passage area changing member 11 counterclockwise in FIG. 2, a permanent magnet 15 provided near a portion of the passage area changing member 11 which is in sliding contact with the inner peripheral wall of the main body 2, And an electromagnet 16 provided on the inner peripheral wall of the main body 2. The electromagnet 16 is disposed so as to be located at a predetermined distance counterclockwise from the permanent magnet 15 in the initial position, and when the electromagnet 16 is energized to generate an electromagnetic attraction, the electromagnet 16 becomes permanent. When the magnet 15 is drawn toward the electromagnet 16 by the electromagnetic attraction, the passage area changing member 11 rotates counterclockwise integrally with the permanent magnet 15. When the magnetic attraction force of the electromagnet 16 is interrupted, the urging force of the compression spring 14 causes the passage area changing member 11 to return to the initial position.

In the initial position, as shown in FIG. 4 (a), the fuel swirling member 8 and the passage area changing member 11 have the same position in contact with the inner peripheral wall of the main body 2 and rotate in the rotational direction. As described above, when the passage area changing member 11 is rotated by energizing the electromagnet 16 as described above, as shown in FIG. The rotational position of the passage area changing member 11 is shifted, and a throttle that narrows the fuel passage 10 formed between the inner peripheral wall of the main body 2 and the fuel swirling member 8 is formed.

FIG. 4 shows a case in which the throttle is rotated by a larger angle than the original rotation angle, in order to clearly show the formation of the throttle by the rotation of the passage area changing member 11. The shape of the passage area changing member 11 is shown in a simplified manner.

The fuel at a predetermined pressure is fed to the fuel injection valve 1 at an early stage of injection. Since the fuel injection valve 1 is filled with the fuel at the predetermined pressure at the beginning of injection, The fuel is injected at the predetermined pressure regardless of the rotational position of the passage area changing member 11. Here, when the throttle is formed by rotating the passage area changing member 11, the pressure of the injected fuel decreases, but the outer shape of the spray depends on the initial swirling force of the spray and the non-swirl. And the passage area changing member 11 after the start of injection.
Even if the fuel pressure drops due to the throttle, there is no significant change in the external shape of the spray, the fuel concentration inside the spray and the spray particle size change, and the fuel injection rate (injection amount per unit time) changes become.

FIG. 5 is a block diagram showing a control function of the fuel injection valve 1 in an internal combustion engine provided with the fuel injection valve 1. In the internal combustion engine 51 shown in FIG. 5, the fuel injection valve 1 is provided for each cylinder such that the injection hole 3 directly faces the combustion chamber 52. The fuel injected from the fuel injection valve 1 and the air sucked into the combustion chamber 52 through the tumble intake port 54 by opening the intake valve 53 in the intake stroke form a combustion mixture, and the combustion mixture is formed. The air-fuel mixture is ignited and burned by spark ignition by the spark plug 55. The exhaust gas after combustion is discharged through an exhaust port 57 by opening an exhaust valve 56 in an exhaust stroke.

As described above, the internal combustion engine 51 shown in FIG.
Is a direct in-cylinder injection spark ignition engine, which performs a fuel injection in an intake stroke to form a homogeneous mixture,
Stratified combustion, in which fuel injection is performed in a compression stroke to form a stratified mixture, is switched according to operating conditions.

Here, the needle valve 5 in the fuel injection valve 1 is used.
As means for controlling the operation of (the energization of the electromagnetic coil 6),
An in-cylinder pressure calculating means 101, a differential pressure calculating means 102, an injection valve injection rate determining means 103, a fuel injection rate calculating means 104, a fuel injection amount correcting means 105, and a fuel injection amount controlling means 106 are provided. As means for controlling the rotational position of the passage area changing member 11 (energization of the electromagnet 16) in the injection valve 1, an injection valve injection rate control means 107 is provided.

The in-cylinder pressure calculating means 101 calculates the in-cylinder pressure at the injection start time from the crank angle θ at the injection start time and the average value of the intake pipe negative pressure.
Reference numeral 2 denotes a differential pressure between the pressure of the fuel supplied to the fuel injection valve 1 and the in-cylinder pressure at the injection start timing calculated by the in-cylinder pressure calculating means 101.

The injection valve injection rate determining means 103 determines a reference injection rate from the differential pressure and the fuel supply pressure, and the fuel injection rate calculating means 104 determines the rotational position of the passage area changing member 11 in each cylinder. The actual injection rate in each cylinder is determined according to the passage area).

Then, in the fuel injection amount correcting means 105,
The fuel injection amount is corrected according to the injection rate, and the fuel injection amount control means 106 controls the opening of the fuel injection valve 1 based on the corrected fuel injection amount.

On the other hand, the injection valve injection rate control means 107 sets the target angle of the passage area changing member 11 according to the operating conditions, and controls the rotational position of the passage area changing member 11 based on the target angle.

FIG. 6A shows a region where stable combustion can be obtained when stratified combustion is performed at a certain engine speed (rpm), using ignition timing and injection timing (injection timing) as variables. The stable combustion region has characteristics that vary depending on the injection period (injection pulse width).

Here, the engine speed (rpm) in FIG.
If the engine rotational speed decreases and changes from the condition (1), the crank angle corresponding to the injection pulse width decreases and changes even if the injection pulse width (injection time) is the same, and as shown in FIG. The combustion area will be reduced. That is, in stratified charge combustion, a rich mixture needs to be unevenly distributed around the ignition plug at the ignition timing, but when the injection is completed at a small angle, the rich mixture stays around the ignition plug. Since the angle period is narrowed, it becomes necessary to limit the injection timing to a narrower angle range.

On the other hand, if the engine speed is increased and changed from the engine speed condition in FIG. 6A, the crank angle corresponding to the injection pulse width is increased and changed even if the injection pulse width is the same. Since the injection is performed at a relatively large angle, the angle period during which the rich air-fuel mixture stays around the spark plug becomes wide, and if there is no influence of gas flow, the injection timing is set within a wider angle range. Although it is possible to change it, at the time of high rotation, the mixture is violently stirred by the strong gas flow, so that the stratification of the mixture is reduced, and as shown in FIG. In order to ensure stable stratification while performing stable combustion, the stable combustion region also decreases.

Therefore, in the present embodiment, in the stratified combustion region, the injection rate of the fuel injection valve 1 can be changed by controlling the throttle of the fuel swirl passage based on the rotational position of the passage area changing member 11, as shown in FIG. By controlling the fuel passage area (injection rate) in accordance with the engine output torque (engine load) and the engine speed in this way, the pulse width in crank angle does not change significantly under operating conditions, as shown in FIG. Thus, the combustion stable region can be secured widely regardless of the operating conditions. Further, a correction corresponding to the injection rate is made to the injection pulse width so that the required fuel amount can always be injected in response to the change of the injection rate.

Next, the control of the fuel injection valve 1 will be described in more detail with reference to the flowchart of FIG. S1
In 01, it is determined whether the combustion is in a stratified combustion region or a homogeneous combustion region based on the engine speed (rpm), the water temperature Tw, the accelerator opening, and the like. The target angle θ2 of the passage area changing member 11 is set, and if it is a homogeneous combustion region, the target angle θ2 is set as an initial position.

In the setting of the target angle θ2 in the stratified combustion region, as shown in FIG. 7, the rotation / load is set so that the injection pulse width becomes substantially the same in terms of crank angle regardless of the change in rotation / load. The area of the fuel path is increased (the passage area changing member 11 is brought closer to the initial position) in accordance with the rise of the fuel passage, and the area of the fuel path is reduced (the passage area changing member 11 is moved from the initial position) in accordance with the decrease in rotation and load. Rotation).

At S102, the fuel supply pressure Pfuel is read, and at S103, the passage area A × is calculated based on the target angle θ2 (throttle area) and the fuel supply pressure Pfuel.
The flow coefficient α (the required injection rate at the reference in-cylinder pressure) is obtained.

The flowchart of FIG. 10 shows a routine for calculating the injection pulse width.
The injection start timing crank angle θ, the intake pipe negative pressure average value P, the passage area A × the flow coefficient α are input.

In step S112, the stroke amount y at the injection start timing crank angle θ is calculated. In S113, the cylinder volume V at the injection start timing is calculated by multiplying the stroke amount y by the bore area.

In step S114, the in-cylinder pressure P at the injection start timing is calculated from the intake pipe negative pressure average value P and the in-cylinder volume V.
Find c. In S115, the pressure difference Pf between the fuel supply pressure Pfuel and the in-cylinder pressure Pc, that is, the injection hole 3 at the start of the injection,
Find the differential pressure before and after.

In S116, the differential pressure Pf and the reference differential pressure P
0, the injection rate K is calculated based on the reference injection rate K0 when the passage area changing member 11 is not used as the reference position and the flow path is not throttled.

In S117, the passage area changing member 11
The passage area A × flow coefficient α according to the target angle θ2
Then, the actual injection rate K ′ is calculated from the passage area Astd when the passage area changing member 11 is set to the initial position.

In S118, the required fuel amount Tp (ms) according to the air amount in the cylinder and the target air-fuel ratio, the injection rates K, K ',
The injection pulse width Ti (Ti = (Tp
/ K) + Ts) and Ti '(Ti' = (Tp / K ') + Ts).

Normally, the opening of the fuel injection valve 1 is controlled using the injection pulse width Ti ′. However, the passage area changing member 11 is rotationally driven by, for example, disconnection of an energizing circuit for the electromagnet 16. The injection pulse width Ti is also calculated at the same time so that it can be used in cases where it is not possible.

In S119, the injection pulse width Ti 'is changed to Ti'.
Store in old. By the way, even if a request for changing the injection rate is generated in response to a change in rotation or load, in the cylinder for which the injection pulse width has already been determined (set), the passage area is changed in response to the request for changing the injection rate. When the rotational position of the member 11 is changed, a difference occurs between the injection rate when the injection pulse width is set and the injection rate when the fuel is actually injected, and corresponds to the air amount in the cylinder and the target air-fuel ratio. The required amount of fuel cannot be injected, and the air-fuel ratio control accuracy deteriorates.

Therefore, for example, as shown in FIG. 11, for a cylinder (# 1 cylinder) for which the injection pulse width has already been set when the injection rate change request is issued, the fuel injection is ended. The injection rate is changed by changing the rotational position of the passage area changing member 11 from the other cylinders (#
For the two cylinders to # 4 cylinder), the injection rate is changed by changing the rotational position of the passage area changing member 11 at the same time when the request is generated.

That is, during the period from the determination of the injection pulse width to the end of injection with the injection pulse width, the change of the injection rate for the corresponding cylinder is prohibited. As shown in the flowchart of FIG. 12, the injection rate of each cylinder is changed.

In S121, the passage area A × the flow coefficient α
(Required injection rate), engine speed (rpm), water temperature Tw, and accelerator opening are input. In S122, it is determined whether or not the injection rate change request is generated by determining whether or not the previous injection rate in the # 1 cylinder and the latest required injection rate input in S121 this time match.

Here, when it is not necessary to change the injection rate, the flow proceeds to S127. However, when the injection rate of the # 1 cylinder up to the previous time is different from the latest required injection rate inputted in S121 this time, the flow proceeds to S123. .

In step S123, a period from the reference crank position REF for setting the injection pulse width of the # 1 cylinder to the injection period (injection end time) (injection rate change inhibition period: see FIG. 11)
Is determined. During the above period, the injection pulse width at the next injection timing cannot be changed, and therefore it is not possible to cope with the change of the injection rate. Therefore, when it is determined that the period is within the above period, the process proceeds to S124 and # 1 is performed. For the cylinder, the injection rate (rotational position of the passage area changing member 11) up to the previous time is maintained without changing to the latest required injection rate.

On the other hand, when it is determined in S123 that the period is not the injection rate change prohibition period, the process proceeds to S125, and # 1 is executed.
The latest required injection rate is set to the injection rate in the cylinder, and in the next S126, the changed injection rate is set so as to be the changed injection rate.
The rotational position of the passage area changing member 11 of the fuel injection valve 1 provided in the # 1 cylinder is changed (injection rate control means).

When the energization of the electromagnet 16 is duty-controlled, the rotational position of the passage area changing member 11 is changed by changing the duty ratio. Similarly, for the # 3 cylinder, the # 4 cylinder, and the # 2 cylinder, if the injection rate change is not within the injection rate change prohibition period, the change of the injection rate is suspended, and if not, the injection rate is changed. (S127 to S141).

In S142, the injection rate of each cylinder is stored as the previous value. By the way, in the above-described embodiment, when there is a request to change the injection rate, the injection rate (the rotational position of the passage area changing member 11) is not set during the injection rate change prohibition period.
And the injection rate (rotational position of the passage area changing member 11) is maintained unless the required injection rate changes again. However, as shown in FIG. In order to hold the changing member 11 in the initial position and reduce the injection rate during the injection period, the passage area changing member 1
1 may be rotationally driven.

As described above, even when the injection rate is changed during the injection period, the injection rate change request is received from the reference crank position REF for setting the injection pulse width to the injection end timing. In the case shown in FIG. 13, the change in the injection rate is reflected in the determination of the injection pulse width of the closest # 3 cylinder after the request to change the injection rate, and the injection timing of the # 3 cylinder is , The area of the fuel passage of the fuel injection valve of the # 3 cylinder is changed.

In the case shown in FIG. 13, the electromagnet 16 is turned ON / O.
The FF drive is performed so that the passage area changing member 11 is located at one of the initial position (the maximum injection rate position) and the maximum rotation position (the minimum injection rate position). During the non-injection period, the electromagnet 16 is turned off. During the injection period, the electromagnet 1 is turned off for a time corresponding to the required injection rate.
6 is turned on so that the average injection rate becomes the target injection rate.

Accordingly, when the required injection rate is the maximum injection rate, the electromagnet 16 is kept off during the injection period, and when the required injection rate is the minimum injection rate, the electromagnet 16 is turned on during the entire injection period. Just keep it. When the required injection rate is between the minimum injection rate and the maximum injection rate, the ON time of the electromagnet 16 ending at the end of the injection is
The average injection rate becomes the required injection rate by controlling the ratio between the period in which the injection is performed at the maximum injection rate in the first half and the period in which the injection is performed at the minimum injection rate in the second half. To do.

With the above configuration, the passage area changing member 11
Even if the resolution of the rotational position is low, the injection rate can be finely controlled, the decrease in fuel pressure in the early stage of the injection that determines the spray shape can be suppressed as much as possible, and the change in the spray shape due to the change in the injection rate can be further suppressed. .

The injection rate during the injection period is controlled by driving the passage area changing member 11 to an angular position corresponding to the required injection rate from the start of the injection to hold the position during the injection period. However, the resolution of the injection rate control is governed by the resolution of the rotational drive position of the passage area changing member 11, making it difficult to finely control the injection rate and suppressing the decrease in fuel pressure at the beginning of the injection. Will also fade.

FIGS. 14 to 16 show the passage area changing member 11.
A fuel swirl passage formed between the fuel swivel member 8 and the fuel swivel member 8 so as to be offset from the axis of the needle valve 5 and extend substantially in the radial direction of the valve seat to communicate the through hole 8a with the peripheral portion. It shows the form.

The fuel swirl passage includes fuel swirl passages 71 a and 71 b formed on the contact surface side of the fuel swirl member 8 with the passage area change member 11, and the passage swirl member 11.
The fuel swirl passages 72a and 72b are formed on the contact surface side of the fuel swirl member 8 with the fuel swirl members 72a and 72b.

The fuel swirl passages 71a and 71b formed in the fuel swirl member 8 are parallel to each other and are similar to the fuel swirl passages 9a and 9b formed on the opposite surfaces.
Is extended in the radial direction of the valve seat so as to be offset with respect to the axis of the valve seat, and is formed so as to communicate with the through hole 8a and the peripheral edge portion, and further, a direction orthogonal to the fuel swirl passages 9a and 9b. Will be extended.

Further, the fuel swirl passages 72a and 72b formed in the passage area changing member 11 are
Is rotated to the maximum rotation position (minimum injection rate position) and overlaps with the fuel swirl passages 71a and 71b (FIG. 14).
(See (b)), when the passage area changing member 11 is at the initial position (maximum injection rate position), the maximum rotation position (minimum injection rate position) and the initial position (maximum injection rate position) with respect to the 71a and 71b. 14) is formed at a position shifted by an angle corresponding to an angle change between the above (see FIG. 14A).

According to the above configuration, the passage area changing member 11
As the is rotated from the initial position, the turning component is strengthened. At the initial position, the fuel injected through the fuel swirl passages 72a and 72b and the fuel injected through the fuel swirl passages 71a and 71b interfere with each other. On the other hand, when the passage area changing member 11 is rotated, the fuel swirl passages 72a, 72
Since b and the fuel swirl passages 71a and 71b are integrated and inject fuel in the same direction, the swirl component is strengthened.

On the high rotation speed / high load side in the stratified combustion region, since the gas flow depending on the rotation is strong, it is necessary to narrow the spray angle by the increased gas flow. On the other hand, as described above, the passage area changing member 11 is controlled to a position closer to the initial position as the rotation speed and the load become higher, so that the turning component is weakened as the rotation speed and the load become higher. Since the swirl component is weakened, the spray angle becomes narrow, and a narrow spray shape corresponding to the above demand can be obtained. That is, according to the above configuration, it is possible to control the spray rate according to the rotation and load at that time while controlling the injection rate according to the rotation and load.

In the above description, the injection rate is increased in accordance with the increase in rotation and load so that the injection pulse width in crank angle conversion is substantially the same. However, the present invention is not limited to such characteristics. For example, in contrast to the characteristic of FIG. 7 in which the injection pulse width in terms of crank angle is substantially the same, as shown in FIG. The rate may be set low. In the characteristics shown in FIG. 17, the injection period on the high load side is longer than the injection period on the low load side, and the residence time of the fuel around the spark plug on the high load side is longer. The degree of freedom of the injection timing at which the combustion stability is obtained on the load side is further increased (see FIG. 18).

Further, in the above embodiment, the area of the fuel passage on the upstream side of the fuel swirling member 8 is controlled by controlling the rotational position of the passage area changing member 11, but as shown in FIG. Alternatively, a configuration may be employed in which the area of the fuel passage is controlled by expanding and contracting the laminated piezoelectric element in the axial direction of the injection valve.

In FIG. 19, the same elements as those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted. FIG.
In (2), one end of a cylindrical laminated piezoelectric element 91 is fixed to a needle valve stopper 92, and the needle valve 5 is inserted into a hollow portion of the laminated piezoelectric element 91. The laminated piezoelectric element 9
1 is provided with a flange portion 94 on the outer periphery of which an O-ring 93 is fitted.
Is fitted into the cylindrical hollow portion of the main body 2.

The lower surface of the flange portion 94 faces the upper end surface of the fuel swirling member 8 at a predetermined interval, and the fuel is annularly sandwiched between the inner wall of the hollow portion of the laminated piezoelectric element 91 and the outer wall of the needle valve 5. The fuel is introduced into the fuel passage 10 on the outer peripheral portion of the fuel swirling member 8 through a passage and a gap between the lower surface of the flange portion 94 and the upper end surface of the fuel swirling member 8.

Here, as shown in FIG. 20 (a), when no voltage is applied to the laminated piezoelectric element 91, a gap between the lower surface of the flange portion 94 and the upper end surface of the fuel swirling member 8 is increased. When a voltage is applied to the laminated piezoelectric element 91 so that the diaphragm does not become a stop, the laminated piezoelectric element 91 is extended as shown in FIG. It is displaced downward along the axial direction and narrows the gap between the lower surface of the flange portion 94 and the upper end surface of the fuel swirling member 8 to form a throttle. That is, by applying a voltage to the laminated piezoelectric element 91, the injection rate can be reduced.

Since the laminated piezoelectric element 91 has good responsiveness, the injection rate can be changed during injection as shown in FIG. 13, and the injection rate can be changed by controlling the applied voltage. Minor changes are possible.

FIG. 21 shows that the gap between the lower surface of the flange portion 94 and the upper end surface of the fuel swirling member 8 is changed in two steps by controlling the application of voltage to the laminated piezoelectric element 91 in an ON / OFF manner. 7 is a flowchart illustrating an embodiment in which the average injection rate is controlled to a required injection rate based on a time ratio in which the fuel path is narrowed during the injection.

At S151, the injection start timing crank angle θ, the intake pipe negative pressure average value P, and the required throttle area change ratio DD corresponding to the required injection rate are input. In S152, the stroke amount y at the injection start timing crank angle θ is calculated.

In S153, the cylinder volume V at the injection start timing is calculated by multiplying the stroke amount y by the bore area. In S154, the in-cylinder pressure Pc at the injection start timing is obtained from the intake pipe negative pressure average value P and the in-cylinder volume V.

In S155, the pressure difference Pf between the fuel supply pressure Pfuel and the in-cylinder pressure Pc, that is, the injection hole 3 at the start of injection,
Find the differential pressure before and after. In S156, based on the differential pressure Pf, the reference differential pressure P0, and the reference injection rate K0, the injection rate K in a state where no voltage is applied to the laminated piezoelectric element 91 (maximum area) is calculated.

In S157, the required injection rate K 'is obtained from the required throttle area change ratio DD. In S158, the required fuel amount T according to the air amount in the cylinder and the target air-fuel ratio is determined.
The injection pulse width Ti (Ti = (Tp / K) + Ts), Ti ′ (Ti ′ = p (ms), the injection rate K, K ′, and the invalid injection time Ts.
(Tp / K ') + Ts) is calculated. Normally, the opening of the fuel injection valve 1 is controlled using the injection pulse width Ti ′.
For example, the injection pulse width Ti corresponding to the case where the throttling is not performed is used so that the throttling area cannot be reduced and the injection rate cannot be reduced due to disconnection of the energizing circuit for the laminated piezoelectric element 91 or the like. Is also calculated at the same time.

In S159, the crank angle from the start of the injection to the time when the voltage is applied to the laminated piezoelectric element 91, that is, the start time Tica of the voltage application to the laminated piezoelectric element 91
Is calculated as follows.

Tica = injection start timing + Ti ′ (converted to crank angle) × (1−DD) The required change ratio DD is set such that the voltage application state to the multilayer piezoelectric element 91 is changed to 100% and the multilayer piezoelectric element 91 is changed.
The voltage non-application state with respect to is set to a change rate of 0%, and 0%
It is set between ~ 100% according to the operating conditions. For example, when a change rate of 100% corresponding to the minimum injection rate is required, the application of the voltage to the multilayer piezoelectric element 91 is continued from the injection start timing to the injection end timing, and the minimum injection control that can be actually controlled is performed. Inject at a rate.

If the required change ratio DD is 0%, the voltage is not applied to the multilayer piezoelectric element 91 from the injection start timing to the injection end timing, and the control is performed at the maximum controllable injection rate that can be actually controlled. Is performed.

Further, when the demand change ratio DD is an intermediate value, the injection period (maximum injection rate period) in the state where no voltage is applied to the first half of the laminated piezoelectric element 91 and the voltage of the second half of the laminated piezoelectric element 91 are changed. The injection period (minimum injection rate period) in the applied state is controlled so that the average injection rate becomes a value corresponding to the required change rate DD (required injection rate K ′) (see FIG. 22). .

In S160, the injection pulse width Ti 'is changed to Ti'.
Store in old.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment in which a passage area changing member is rotated to change a fuel passage area.

FIG. 2 is a partially enlarged view showing a mechanism for rotating a passage area changing member in the embodiment.

FIG. 3 is a partially enlarged view showing an injection hole portion of the fuel injection valve in the embodiment.

FIG. 4 is a state diagram for explaining how a fuel passage area changes in the embodiment.

FIG. 5 is a diagram showing a mounting state and control blocks of a fuel injection valve according to the embodiment.

FIG. 6 is a diagram showing a problem when the injection rate is fixed.

FIG. 7 is a diagram showing control characteristics of a fuel passage area according to load and rotation.

FIG. 8 is a diagram showing the effect of fuel passage area control according to load and rotation.

FIG. 9 is a flowchart showing how a target injection rate is set.

FIG. 10 is a flowchart showing a state of calculation of an injection pulse width.

FIG. 11 is a time chart showing a change timing of an injection rate.

FIG. 12 is a flowchart illustrating a state of injection rate switching control for each cylinder.

FIG. 13 is a time chart showing an embodiment in which the injection rate is changed during injection.

FIG. 14 is a state diagram showing an embodiment in which the swirl component is changed at the same time as the fuel passage area is changed.

FIG. 15 is a cross-sectional view illustrating the above embodiment.

FIG. 16 is an exploded perspective view showing the above embodiment.

FIG. 17 is a diagram showing a characteristic in which the injection rate on the high load side is made lower than the characteristic in which the injection pulse width is made substantially constant over the entire area in controlling the fuel passage area.

FIG. 18 is a diagram illustrating an effect when the injection rate is reduced on the high load side.

FIG. 19 is a sectional view of a fuel injection valve showing an embodiment in which a fuel passage area is changed by a laminated piezoelectric element.

FIG. 20 is a state diagram showing control of a fuel passage area using a laminated piezoelectric element.

FIG. 21 is a flowchart showing an embodiment in which the injection rate is switched during injection to make the average injection rate coincide with a required value.

FIG. 22 is an explanatory diagram showing an embodiment in which the injection rate is switched during injection to make the average injection rate coincide with a required value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve 2 ... Main body 3 ... Injection hole 4 ... Valve seat 5 ... Needle valve 6 ... Electromagnet 8 ... Fuel swirl member 9a, 9b ... Fuel swirl passage 10 ... Fuel passage 11 ... Passage area change member 15 ... Permanent magnet 16 …electromagnet

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuyuki Ito F-term in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa 3G066 AA02 AB02 AD12 BA14 BA19 BA51 BA67 CC06U CC14 CC20 CC37 CC43 CC48 CC66 CC68U CD26 CE22 CE27 CE34 DA01 DA08 DA12 DA16 DB09 DB11 DB13 DC04 DC05 DC09 DC14 DC18 DC19

Claims (9)

[Claims] 1. A fuel injection valve having a fuel swirl passage extending substantially radially of a valve seat, and comprising a fuel swirl member for applying a swirl force to fuel by the fuel swirl passage. Injection rate changing means for changing the injection rate by changing the fuel passage area on the upstream side of the fuel turning member, and injection rate control means for controlling the injection rate changing means in accordance with the operating conditions of the engine are provided. A fuel injection valve for an internal combustion engine, characterized in that: 2. The internal combustion engine according to claim 1, wherein said injection rate changing means changes a fuel passage area according to a rotational position of a passage area changing member which is driven to rotate around an axis of said valve seat. Fuel injection valve. 3. A fuel swirl passage provided in the fuel swirl member and having a fuel swirl passage extending substantially in a radial direction of a valve seat and applying a swirl force to fuel. 3. A fuel injection valve for an internal combustion engine according to claim 2, wherein the fuel swirl component is changed at the same time as the fuel passage area is changed by changing a relative angle with respect to a fuel swirl passage provided in the passage area changing member. 4. The fuel injection valve for an internal combustion engine according to claim 1, wherein said injection rate changing means changes a fuel passage area according to a position of a passage area changing member which is displaced in an axial direction of said valve seat. . 5. A fuel injection valve for an internal combustion engine according to claim 4, wherein said passage area changing member is constituted by a laminated piezoelectric element. 6. The fuel injection for an internal combustion engine according to claim 1, wherein said injection rate control means controls said injection rate changing means in accordance with the engine speed. valve. 7. The injection rate control means for inhibiting the change of the injection rate by the injection rate changing means during a period from the determination of the injection pulse width to the end of injection by the injection pulse width. A fuel injection valve for an internal combustion engine according to any one of claims 1 to 6, characterized in that: 8. The internal combustion engine according to claim 1, wherein said injection rate control means changes the injection rate by said injection rate changing means during fuel injection. Fuel injection valve. 9. The fuel injection valve according to claim 1, wherein the injection rate control means controls the average injection rate of the fuel injection valve by controlling the ratio of a period during which the injection rate before the injection end timing is reduced and the fuel is injected. The fuel injection valve for an internal combustion engine according to claim 8, wherein