JPH08334072A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

PURPOSE: To improve an exhaust characteristic and operability or the like by freely changing an injection rate characteristic of a fuel injection valve in a desired operating condition. CONSTITUTION: A push rod 109 with which a needle 114 comes into contact when it is lifted, is provided, and a high pressure chamber 108 is arranged above the push rod 109. Pressure in the high pressure chamber 108 is maintained and released under high pressure by a spool valve 106. In a low speed low load area, the spool valve 106 is closed, and the push rod 109 is made freely movable, and an initial injection rate is enhanced, and combustion stability is enhanced. In a low medium speed high load area, the spool valve 106 is opened, and pressure in the high pressure chamber 108 is made to act on the push rod 109, and after a lift quantity is regulated, the valve is closed again, and the push rod 109 is made freely movable, and the initial injection rate is restrained, and NOx and a noise are reduced. In a high speed area, the spool valve 106 is closed → opened →closed at a stretch, and the push rod 109 is made freely movable, and restraint to the initial injection rate is prevented, and discharge of black smoke or the like is restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a technique for improving a fuel injection control device for a diesel engine.

[0002]

2. Description of the Related Art As a conventional fuel injection control device for a diesel engine, there is a fuel injection control device using a fuel injection valve as shown in FIG. 7, for example. Is also disclosed. The fuel injection valve shown in FIG. 7 is a so-called two-stage valve opening pressure (two spring) nozzle, which is slidable in the vertical direction in the drawing.
Valve body (hereinafter, needle [needle valve])
204), a push rod 209 that abuts on the upper end portion of the needle 204 via an initial lift gap adjusting shim 207 and is slidably inserted and held in the nozzle holder 208 in the vertical direction, and the push rod 209. 209 and a set screw 214 are interposed between the push rod 209, the initial lift gap adjusting shim 207, and the first spring 212 for pressing the needle 204 downward in the drawing,
It has.

The initial lift gap adjusting shim 20 is also used.
7, a spring seat 218 pressed by the second spring 210 is provided in the nozzle holder 208 while being positionally regulated by the spacer 206 so as to have a predetermined gap L1 with the upper surface of the initial lift gap adjusting shim 207. Has been. The nozzle body 203 and the spacer 206 are fastened and fixed to the nozzle holder 208 with a retaining nut 219.

In such a structure, the high-pressure fuel pumped by the fuel injection pump (not shown) is supplied to the fuel inlet 201 of the nozzle holder 208 through the fuel pipe (not shown).
To the nozzle body 203 through the fuel passage 202 in the nozzle holder 208.
When the fuel pressure in 03 increases, the needle 204 is pushed upward by the fuel pressure to open the valve.

At the time of opening the valve, first, the needle 204 is
Until the upper surface of the initial lift clearance adjusting shim 207 abuts the lower surface of the spring seat 218, that is, until the predetermined clearance L1 disappears, the first spring 212 is pressed through the push rod 209 or the like. It moves upward in the figure against the pressure to open the valve (first stage valve opening). That is, the initial lift clearance adjustment shim 207
The gap L1 between the spring seat 218 and the spring seat 218 determines the lift amount of the first stage, that is, the initial lift (hereinafter, also referred to as pre-lift) amount, and the initial lift amount L1.
Can be adjusted by adjusting the thickness of the initial lift gap adjusting shim 207.

The first-stage valve opening pressure is determined by the pressing force of the first spring 212, and is adjusted by adjusting the screwing depth of the set screw 214 and the thickness of the first-stage valve opening pressure adjusting shim 213. It can be adjusted by changing the set load of the first spring 212. And
When the needle 204 is further pushed upward after the first stage valve opening until the upper surface of the above-mentioned lift clearance gap adjusting shim 207 and the lower surface of the spring seat 218 contact each other, the needle 204 is The first spring 212
And the second provided above the spring seat 218
It moves upward in the figure against the spring 210 and is opened (the second stage valve opening). The second stage valve opening continues until the sliding shoulder 205 on the upper portion of the needle 204 and the spacer 206 come into contact with each other. Therefore, the needle 2
The total lift amount of 04 is determined by the gap L2 between the sliding shoulder 205 and the spacer 206. Further, the valve opening pressure of the second stage is
Although it is determined by the approximate combined force of the first spring 212 and the second spring 210, the shim 211 for adjusting the second stage valve opening pressure is used.
It can be adjusted by adjusting the thickness of the.

In such a conventional two-stage valve opening pressure nozzle, the valve opening pressure of the first stage and the lift amount can be set small in addition to the valve opening characteristic of the second stage. Since the initial injection rate can be suppressed to a low level without lowering the oil rate, the premixed combustion rate can be suppressed, thereby suppressing NOx generation and noise.

[0008]

However, in the above-described conventional two-stage valve opening pressure nozzle structure, the initial injection rate is constantly reduced regardless of the operating region, so NOx at low speed and high load is provided. Noise can be reduced, but fuel injection timing delay (retard) at low speed and low load,
In an engine that performs exhaust gas recirculation, high swirl, etc., if the initial period injection rate is suppressed, the injection period will be extended and the fuel injection pressure will decrease, making it possible to sufficiently atomize the fuel spray. If it does not exist, instability of combustion, misfire, etc. will be caused, and there is a problem that operating performance and exhaust performance may be deteriorated. Further, even in the case of a normal engine, at the time of low temperature starting, there is a possibility that the startability is deteriorated and white smoke is increased due to the same reason as above.
Moreover, at low speed and low load, the pre-lift amount between the cylinders and the setting variation of the valve opening pressure may or may not cause the second stage valve opening, so that the injection amount, the injection pressure, etc. vary and the rotation fluctuation occurs. May increase.

Further, in the high speed range, the initial injection rate is suppressed so that the fuel injection pressure is lowered, the injection period is extended, and the combustion period is extended, which may deteriorate fuel efficiency and black smoke. At the end of injection, the first spring 21
After the spring seat 218 is seated by the resultant force of the second spring 210 and the second spring 210, the needle 204 is further lowered and seated only by the first spring 212. In the high-speed region where the reflected wave in the fuel pipe changes rapidly and is large,
So-called secondary injection or the like is likely to occur and black smoke or the like may be deteriorated.

The present invention has been made in view of the above conventional problems, and the fuel injection of an internal combustion engine in which the above-mentioned problems can be solved by freely changing the injection rate characteristics in a desired operating condition. An object is to provide a control device.

[0011]

For this reason, a fuel injection control device for an internal combustion engine according to a first aspect of the present invention has a first injection characteristic for controlling the lift amount of a valve element at the time of valve opening in one stage,
A fuel injection valve configured to be switchable between a second injection characteristic that controls the lift amount of the valve element when opening the valve in a plurality of stages to suppress the initial injection rate of fuel, and a first injection characteristic of the fuel injection valve. And the second injection characteristic, and an injection characteristic switching means for switching the second injection characteristic according to the operating state.

According to another aspect of the present invention, the fuel injection valve has a valve body that is biased by a valve body holding portion via an elastic body to close the valve body, and a predetermined gap is formed between the valve body in the valve opening direction. And a lift amount restricting means for restricting the lift amount of the valve element when the valve is opened, and a lift amount restricting means for controlling the predetermined gap to control the lift amount of the valve element. And a lift amount control means for controlling the lift amount of the valve element by the lift amount control means in a desired operating state, and the first injection characteristic, The second injection characteristic and the second injection characteristic are switched.

According to a third aspect of the invention, the lift amount control means includes a high pressure chamber for supplying a pressure acting on the lift amount regulation means, and a high pressure chamber is provided via the pressure control means. By controlling the pressure in the chamber, the lift amount of the valve body is controlled.

According to a fourth aspect of the present invention, the fuel injection valve includes a valve element held by a valve element holding portion and a first element for normally urging the valve element toward the valve element holding portion in a valve closing direction. Of the elastic body and the second elastic body installed so as to start pressing the valve body in the valve closing direction after the valve body is lifted by a predetermined amount, and the installation position of the second elastic body is changed. However, by changing the pressing start position, the installation position control means for controlling the predetermined amount, and the injection characteristic switching means, in the desired operating state, through the installation position control means. By changing the installation position of the second elastic body, the predetermined amount is controlled, and the first injection characteristic, the second injection characteristic, and
The switch is configured to switch.

In a fifth aspect of the present invention, the injection characteristic switching means is provided in a low / medium speed / high load region and a medium speed / low load region.
The second injection characteristic is selected, and the first injection characteristic is selected in an operation region other than that. In the fuel injection control device for the internal combustion engine according to the invention as set forth in claim 6, fuel injection is performed in the low-medium-speed high-load region and the medium-speed low-load region with injection characteristics that suppress the initial injection rate, and other operations are performed. In the region, the fuel injection is performed from the initial stage of injection with the injection characteristics with the injection rate increased.

[0016]

In the invention according to claim 1 having the above-mentioned structure,
The injection characteristic switching means controls the lift amount of the valve element in one stage when the fuel injection valve is opened, according to a desired operating state of the internal combustion engine, and the first injection characteristic, and the valve when the fuel injection valve is opened. The lift amount of the body is controlled in a plurality of stages to switch between the second injection characteristic that suppresses the initial injection rate of fuel. This makes it possible to meet the demand for injection rate characteristics according to a desired operating state without incurring a significant increase in cost due to a complicated and large-sized fuel injection pump structure, which is inexpensive and simple. The configuration can improve operation performance, exhaust performance, and the like.

According to a second aspect of the present invention, a fuel injection valve including the lift amount control means and the lift amount control means is used, and the first injection characteristic and the first injection characteristic are provided by the respective means.
The second injection characteristic is switched. Then, for example, the lift amount control means is constituted by one elastic body, a high pressure chamber, and a pressure control means as in the invention according to claim 3. As a result, the above-described operation can be achieved, the structure can be simplified, and the weight of the member (that is, inertial force) that moves with the opening / closing valve operation of the fuel injection valve can be compared with the invention according to claim 4. Since the mass can be reduced, for example, the on-off valve characteristics (generation of asymmetrical injection, etc.) can be further improved.

According to the fourth aspect of the invention, the fuel injection valve is constructed on the basis of the same two spring nozzles as in the conventional art. Therefore, the installation position control means may be provided for the conventional two spring nozzles. Since only a change is required, relatively high reliability can be achieved at low cost, and two springs can be used in combination, so that the degree of freedom in setting the injection characteristics can be increased as compared with the inventions described in claims 2 and 3. Can be large.

According to the fifth aspect of the invention, the second injection characteristic is selected in the low, medium and high load range and the medium and low load range, and the first injection is performed in the other operating range. If the characteristics are selected, for example, in an engine or the like that delays fuel injection timing (retard) at low speed and low load, exhaust gas recirculation, increases swirl, etc., when the initial injection rate decreases at low speed and low load, Instability of combustion, misfire, etc. occur,
It is possible to effectively solve the problem that operating performance and exhaust performance deteriorate.

By the way, in the inventions described in claims 1 to 5, the lift amount of the valve body of the fuel injection valve is variably set so that the injection rate characteristic is changed according to the request. Not limited to this, for example, the fuel injection pump is configured so that the injection rate characteristic can be changed, and as in the invention according to claim 6, the initial injection is performed in the low / medium / high load region and the medium / low load region. Even if the fuel injection is performed with the injection characteristic that suppresses the injection rate and the fuel injection is performed with the injection characteristic that the injection rate is increased from the initial injection in the other operating region, the delay of the fuel injection timing at the low speed and low load (retard ), Exhaust recirculation, high swirl, etc. can stabilize combustion,
Further, it is possible to effectively reduce NOx and noise at low speed and high load.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the overall structure of a fuel injection nozzle adopted in the first embodiment of the present invention. The spring 110 installed in the nozzle holder 116 biases the needle 114 downward in the drawing via a spring seat 112. Then, the spring seat 112
A push rod 109 that functions as a lift amount restricting means of the present invention is provided above the spring seat 112.
The flange portion 10 so as to have a predetermined gap L1 with the upper end surface of the
The nozzle holder 116 is fitted in and held by the nozzle holder 116 so as to be slidable in the vertical direction in FIG. A high pressure chamber 108 is provided above the push rod 109.

The predetermined gap L1, that is, the initial lift amount L
Adjustment No. 1 can be performed by inserting a shim (not shown) between the lower surface of the collar portion 109A of the push rod 109 and the nozzle holder 116 and adjusting the thickness thereof. In addition, the sliding shoulder 114A above the needle 114 and the spacer 11
The lower surface of 3 is set to have a predetermined gap L2 in order to secure the total lift amount L2.

As will be described later, the high pressure chamber 108 is provided with a fuel passage 1 via a spool valve 106 corresponding to the injection characteristic switching means, lift amount control means and pressure control means of the present invention.
The fuel passage 103 is connected to the fuel passage 102 after receiving the high pressure fuel sent from a fuel injection pump (not shown) at the fuel inlet 101. ing.

The side portion 10 of the spool valve 106 is then
6A is branched from the fuel passage 102, and the nozzle body 1
It is arranged so as to face a fuel passage 105 that is branched from the fuel passage 104 connected to 15, and when the high pressure fuel is fed to the fuel passage 105, the high pressure fuel is
The side portion 106A of the spool valve 106 is pressed rightward in the figure.

While the pressing force is smaller than the pressing force of the spring 107 to the left in the drawing, the spool valve 106 is kept pressed to the left in the drawing by the spring 107, and the opening portion 106B of the spool valve 106 is closed. Through the high pressure chamber 1
The communication between 08 and the fuel passage 103 is cut off (corresponding to the operating state 1). When the pressing force of the high-pressure fuel in the fuel passage 105 that presses the spool valve side portion 106A exceeds the pressing force of the spring 107 that presses the spool valve 106 leftward in the drawing, the spool valve 1
06 is moved rightward in the drawing, and the high pressure chamber 108 and the fuel passage 103 are communicated with each other through the opening 106B of the spool valve 106 (that is, the spool valve 106 is opened).
Will be performed (corresponding to operating state 2).

Further, when the spool valve 106 moves to the right, the opening 106B of the spool valve 106 is closed by the nozzle holder 116, and the communication between the high pressure chamber 108 and the fuel passage 103 is cut off again. (Corresponding to operating state 3). The high pressure chamber 1
08 is connected to a spill port (not shown) via an orifice 108A or the like, and is configured to discharge surplus fuel or the like to the outside of the nozzle holder 116.

The operation of the fuel injection valve according to this embodiment having the above structure will be described in detail below. In addition,
The operating region of the engine will be described by dividing it into regions I, II and III shown in FIG. The high-pressure fuel pumped by a fuel injection pump (not shown) flows in from the fuel inlet portion 101 and into the fuel passages 102, 103, 104, 105. The set load of the spring 107 is set so that the spool valve 106 does not open at the fuel pressure in the operating region I.

Therefore, in the operating region I corresponding to the low speed and low load region, when the fuel is supplied to the nozzle body 115 through the fuel passage 104, the needle 114 generated in the nozzle body 115 is moved upward from below. The needle 114 is raised by the pre-lift amount L1 by the ascending force that pushes it up to come into contact with the lower end of the push rod 109, but since the spool valve 106 is not open (see operating state 1), the push rod 108 is Can move upward (the fuel in the high-pressure chamber 108 is spilled),
Since the lift amount of the needle 114 is regulated by the total lift amount L2 without being regulated by the pre-lift amount L1, the initial injection rate is not suppressed, and the injection rate can be increased from the injection start to the end. And the fuel injection pressure that affects atomization of spray can be increased (see FIG. 3).

Therefore, in the operating region I corresponding to the low speed and low load region, atomization of the fuel spray is hindered due to the decrease in the initial injection rate, as in the conventional two-stage valve opening pressure nozzle, and combustion is performed. It is possible to surely suppress the destabilization and the misfire. Next, in the operating region II corresponding to the low, medium and high load regions and the medium and low load regions, the spool valve 106 is moved rightward in the drawing by the high pressure fuel flowing into the fuel passage 105, as shown in the operating state 2. As a result, the fuel passage 103 and the high pressure chamber 108 are communicated with each other, and the fuel pressure in the fuel passage 103 is applied to the upper surface of the push rod 109. Therefore, the lift amount of the needle 114 is equal to or higher than a certain fuel pressure, that is, the rising force by which the fuel pushes the needle 114 upward from above is determined by the resultant force of the spring 110 and the pushing force from the upper surface of the push rod 109. Until it becomes large (this relationship can be adjusted by the pressure receiving area of the fuel pressure, etc.), the pre-lift amount L
It will be limited to 1. That is, the injection rate while the lift amount is regulated to L1, that is, the initial injection rate is suppressed (see FIG. 3).

When the fuel pressure further rises, the spool valve 106 is further moved to the right in the figure and brought into a state as shown in the operating state 3. Therefore, as explained in the operating region I, the spool valve 106 is applied to the upper surface of the push rod 109. The force disappears, and the needle 114 is lifted by the total lift amount L2.
Therefore, at this time, the lift amount is increased and the injection rate can be increased (see FIG. 3).

Therefore, in the operation region II, the injection rate can be increased while suppressing the initial injection rate as in the conventional case, so that the premixed combustion rate is decreased,
Since main combustion can be activated, deterioration of black smoke can be suppressed while reducing NOx and noise. It should be noted that the operation region II is a region that is frequently used and has great significance in improving NOx and noise. In the operating region III corresponding to the high speed region, the spool valve 106 presses the spring 107 at a stretch because the fuel pressure rapidly rises, and immediately shifts to the operating state 3. Therefore, the push rod 109
The pressing force from the top surface of the does not work. Therefore, the operating region I
Similar to the case of (3), since the total lift amount L2 can be secured immediately after the start of injection, the initial injection rate does not decrease (see FIG. 3).

Therefore, as compared with the conventional two-stage valve-opening pressure nozzle, the injection period can be shortened and the problem that black smoke is deteriorated can be solved.
Since the valve 14 can be closed, the seating property of the needle 114 is good, the break in injection can be improved, and the deterioration of black smoke and the like can be suppressed. As described above, according to the first embodiment, the fuel injection rate characteristic can be variably controlled according to the operating state of the engine, so that the initial injection rate is always suppressed as in the conventional two-stage valve opening pressure nozzle. It is possible to improve the driving performance, the exhaust performance, etc. without doing so.

Next, a second embodiment according to the present invention will be described. In the second embodiment, as shown in FIG. 4, the conventional two-stage spring nozzle is used as a basic tone (the same components as those of the conventional one are designated by the same reference numerals), and the spacer 206 and the spring seat 218 are separated from each other. The piezoelectric element 220 is provided in
The fuel injection valve is adapted to adjust the pre-lift amount L1 according to the operating region. That is, the operating region I
In III and III, the piezoelectric element is controlled so that the pre-lift amount L1 becomes the same as the total lift amount L2.
In order to obtain a desired pre-lift amount L1, the piezoelectric element 2
20 is controlled by a control unit or the like. The piezoelectric element 220 and the control unit (not shown) constitute the installation position control means of the present invention. The first spring 212 constitutes the first elastic body of the present invention, and the second spring 210 constitutes the second elastic body of the present invention.

Here, an enlarged view of the piezoelectric element 220 is shown in FIG.
Shown in The piezoelectric element 220 is made of, for example, PZT ceramics, and the nozzle holder 2 of the insertion portion of the second spring 210 is used.
A groove 220A is provided in 08, and the harness 220B is led out to the outside of the nozzle holder 208 through the groove 220A. Then, when no voltage is applied to the piezoelectric element 220 (corresponding to the operating regions I and III), the pre-lift amount L1> the total lift amount L2 is set, and the needle 214 having the pre-lift amount L1 is used. Do not restrict the lift amount.

On the other hand, during the operation of applying a voltage to the piezoelectric element 220 (when it corresponds to the operating region II), the pre-lift amount L1 is configured to be a desired value, and the needle 214 is adjusted by the pre-lift amount L1. The lift amount is regulated. Such control is executed by the control unit, which will be described with reference to the flowchart of FIG.

In step (denoted as S in the figure, the same applies hereinafter) 1, engine speed, accelerator opening, etc. are read. In step 2, it is determined whether or not the current operating state belongs to the operating area II shown in FIG. If YES, the process proceeds to step 3, and if NO, the piezoelectric element 2
The application of voltage to 20 is maintained stopped, and the present flow ends.

In step 3, a voltage is applied to the piezoelectric element 220, and this flow ends. In the second embodiment, the pre-lift amount L1> the total lift amount L2 is set when the piezoelectric element 220 is not operated (when it corresponds to the operation regions I and III) when no voltage is applied. In this case, the piezoelectric element 220 is configured such that the pre-lift amount L1 is zero, that is, the gap between the spring seat 218 and the initial lift gap adjusting shim 207 is zero, and the two springs 210 and 212 are always provided. While preserving the total lift amount L2 by acting on the needle 214, the pre-lift amount L1 is configured to be a desired value during the operation of applying a voltage to the piezoelectric element 220 (when it corresponds to the operation region II). May be.

Further, in the case of the operating region I, the pre-lift amount L1> the total lift amount L2 is set, and only the first spring 212 acts on the needle 214 to secure the total lift amount L2. In addition to improving the injection characteristics at low speeds and low loads (suppressing irregular injection, etc.) while preventing lowering of the injection rate, in the case of operating region III,
By applying a predetermined voltage (voltage in the operating region II) to the piezoelectric element 220, the pre-lift amount L1 becomes zero, that is, the two springs 210 and 212 act on the needle 214 at the same time, and the total lift amount L2. By ensuring the above, it is possible to prevent the initial injection rate from decreasing and further improve the injection characteristics in the high speed region (prevent secondary injection and the like).

As described above, according to the second embodiment, the fuel injection rate characteristic can be variably controlled according to the operating state of the engine. Therefore, as in the conventional two-stage valve opening pressure nozzle, the initial injection is always performed. It is possible to improve operation performance, exhaust performance, etc. without suppressing the rate. By the way, in each of the above-mentioned embodiments, the lift amount of the valve body of the fuel injection valve is configured to be variably controlled according to the operating state. However, by changing the injection rate characteristic by the fuel injection pump, Even if the fuel injection is performed with the injection characteristic in which the initial injection rate is suppressed in the load region and the medium speed / low load region, and with the injection characteristic in which the injection rate is increased from the initial stage of the injection in the other operating regions, Often,
Also by this, combustion can be stabilized even if the fuel injection timing is delayed (retard), exhaust gas recirculation, high swirl, etc. at low speed and low load, and at low speed and high load,
It is possible to effectively reduce NOx and noise.

Further, in each of the above-mentioned embodiments, the lift amount regulation is performed in two stages, but the present invention is not limited to this.
The regulation may be performed in multiple stages. In each of the above-mentioned embodiments, the operating range is divided into I, II, and III, but the present invention is not limited to this, and the injection rate characteristics can be switched in other operating ranges according to the demand by adjusting each part. It is also possible to do so.

[0041]

As described above, according to the invention as set forth in claim 1, the injection characteristic switching means causes the lift of the valve element when the fuel injection valve is opened according to the desired operating state of the internal combustion engine. The first injection characteristic that controls the amount in one step and the second injection characteristic that controls the lift amount of the valve element when the fuel injection valve is opened in multiple steps to suppress the initial injection rate of fuel are switched. Therefore, it is possible to meet the requirement of the injection rate characteristic according to a desired operating condition without incurring a large increase in cost due to a complicated structure of the fuel injection pump and an increase in size. With such a configuration, it is possible to improve operation performance, exhaust performance, and the like.

According to the second aspect of the invention, a fuel injection valve provided with the lift amount regulation means and the lift amount control means is used, and the first injection characteristic and the first injection characteristic are provided by the respective means. Since the two injection characteristics are switched, for example, the lift amount control means is configured by one elastic body, the high pressure chamber, and the pressure control means as in the invention according to claim 3. With this structure, the above-described operation can be achieved, and the structure can be simplified, and the weight of the member that moves in accordance with the opening / closing valve operation of the fuel injection valve as compared with the invention described in claim 4. Since the inertial mass can be reduced, the on-off valve characteristic (generation of asymmetrical injection, etc.) can be further improved.

According to the fourth aspect of the present invention, the fuel injection valve is constructed on the basis of the conventional two spring nozzle, so that the installation position control means may be provided for the conventional two spring nozzle. Since it is possible to make a small change, relatively high reliability can be achieved at low cost and two springs can be used in combination, so that the injection characteristics can be freely set as compared with the inventions described in claims 2 and 3. The degree can be increased.

According to the fifth aspect of the invention, the second injection characteristic is selected in the low, medium and high load regions and the medium and low load regions, and the first injection is performed in the other operating regions. If the characteristics are selected, for example, in an engine or the like that delays fuel injection timing (retard) at low speed and low load, exhaust gas recirculation, increases swirl, etc., when the initial injection rate decreases at low speed and low load, Instability of combustion, misfire, etc. occur,
It is possible to effectively solve the problem that operating performance and exhaust performance deteriorate.

Further, as in the invention described in claim 6, regardless of the type of the control device for the injection rate, the injection characteristics with the initial injection rate suppressed in the low / medium / high load region and the medium / low load region. If the fuel injection is performed and the fuel injection is performed in the other operating region with the injection characteristic that the injection rate is increased from the initial stage of the injection, the fuel injection timing delay (retard) at low speed and low load,
Combustion can be stabilized even when exhaust gas recirculation and high swirl are performed, and NOx and noise can be effectively reduced at low speed and high load.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel injection valve according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining operating regions I, II, and III in the above embodiment.

FIG. 3 is a diagram illustrating fuel injection pressure in each operation region.

FIG. 4 is an overall configuration diagram of a fuel injection valve according to a second embodiment of the present invention.

FIG. 5 is an enlarged view of the piezoelectric element portion of the above embodiment.

FIG. 6 is a flowchart illustrating injection rate control according to the above embodiment.

FIG. 7 is a diagram illustrating a conventional two-stage valve opening pressure nozzle.

[Explanation of symbols]

 102 fuel passage 103 fuel passage 104 fuel passage 105 fuel passage 106 spool valve 108 high pressure chamber 109 push rod 110 spring 114,204 valve body (needle) 115,203 nozzle body (valve body holding portion) 116,208 nozzle holder 201 fuel passage 202 fuel passage 209 push rod 210 second spring 212 first spring 220 piezoelectric element

Claims (6)

[Claims] Claim: What is claimed is: 1. A first injection characteristic that controls the lift amount of the valve element when opening the valve in one step, and a first injection characteristic that controls the lift amount of the valve element when opening the valve in multiple steps to suppress the initial injection rate of fuel. A fuel injection valve configured to be switchable between the second injection characteristic and an injection characteristic switching means for switching the first injection characteristic and the second injection characteristic of the fuel injection valve according to an operating state. A fuel injection control device for an internal combustion engine, comprising: 2. The fuel injection valve is arranged with a predetermined gap between a valve body which is urged to close by a valve body holding portion via an elastic body, and an end portion of the valve body in the valve opening direction. ,
A lift amount control means for controlling the lift amount of the valve body when the valve is opened; and a lift amount control means that acts on the lift amount control means to control the predetermined gap to control the lift amount of the valve body. The injection characteristic switching means controls the lift amount of the valve element by the lift amount control means in a desired operating state to control the first injection characteristic and the second injection characteristic.
The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control device is configured to switch between injection characteristics. 3. The lift amount control means includes a high pressure chamber for supplying a pressure acting on the lift amount regulation means, and a pressure control means for controlling the pressure in the high pressure chamber, wherein the pressure control The pressure in the high-pressure chamber is controlled via the means to control the working pressure to the lift amount regulating means, thereby controlling the lift amount of the valve body. Fuel injection control device for internal combustion engine. 4. A valve body, wherein the fuel injection valve holds a valve body held by a valve body holding portion, and a first body for constantly urging the valve body toward the valve body holding portion in a valve closing direction.
Of the elastic body, the second elastic body installed so as to start pressing the valve body in the valve closing direction after the valve body is lifted by a predetermined amount, and the installation position of the second elastic body is changed. Then, the installation position control means for controlling the predetermined amount by changing the pressing start position is included, and the injection characteristic switching means is operated in a desired operating state via the installation position control means. By changing the installation position of the second elastic body, the predetermined amount is controlled to switch between the first injection characteristic and the second injection characteristic. The fuel injection control device for an internal combustion engine according to claim 1. 5. The injection characteristic switching means selects the second injection characteristic in a low / medium speed / high load region and a medium speed / low load region,
The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the fuel injection control device is a unit that selects the first injection characteristic in an operation region other than that. 6. A low-medium-speed high-load region and a medium-speed low-load region,
A fuel injection control device for an internal combustion engine, characterized in that fuel injection is performed with an injection characteristic that suppresses an initial injection rate, and fuel injection is performed with an injection characteristic that has an increased injection rate from the initial stage of injection in other operating regions.