JP3334455B2 - Fuel injection control method and variable prestroke fuel injection device - Google Patents

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 method for performing fuel injection using a fuel injection valve and a variable prestroke fuel injection device in a combustion chamber of an internal combustion engine, and a variable prestroke fuel injection device used in the method. .

[0002]

2. Description of the Related Art In a fuel injection device for injecting fuel into a combustion chamber of an internal combustion engine through a fuel injection valve, a pre-stroke, which is a stroke before pressurizing a plunger for pressurizing fuel in a pressurizing chamber in a pump body, is variable. Is known. This variable pre-stroke fuel injection device operates a plunger (see FIGS. 1 and 4) up and down by a cam on a cam shaft which rotates at half the engine speed, similarly to a conventional row type injection pump, and pressurizes the fuel. The fuel in the room is pressurized, and the high-pressure fuel is guided to the fuel injection valve, and the fuel injection valve is opened at a predetermined injection pressure or more to perform fuel injection, particularly, directly below a plunger barrel in which the plunger is inserted. The effective stroke (pressurizing stroke after the pre-stroke) can be changed according to the vertical movement of the control sleeve, and the oil can be supplied according to the change in the position of the plunger in the rotation direction. The amount can be varied.

Here, the variable pre-stroke fuel injection device includes a cam PC as shown in FIG. 17 for driving a fuel pressurizing plunger, and a cam lift amount and a cam speed (oil feeding speed) according to the rotation of the cam PC. In proportion to the ratio v: v = cam speed × plunger step area) is changed as shown in FIG. At this time, according to the vertical change of the control sleeve,
The plunger pre-stroke (s1, s2) increases or decreases,
At low speeds, a large pre-stroke s2 is ensured. Even in a low engine speed range, the cam speed is increased to increase the oil supply rate. At high speeds, the pre-stroke s1 is reduced to ensure the same oil supply rate as before. There is an advantage that the advance angle can be achieved without using it. Such a conventional apparatus is disclosed in Japanese Patent Publication No. 63-39791.

In a four-stroke engine, fuel consumption is generally improved by advancing the engine.
In order to improve (reduce) the fuel efficiency in the engine's multiple operating range, it is desirable to advance the angle. On the other hand, in order to reduce NOx, retarding is generally considered, but in addition, it is considered effective to improve the combustion pattern and suppress an excessive increase in the rate of heat generation in the combustion stroke. However, the conventional variable pre-stroke fuel injection device changes the pre-stress angle Ap to change the injection timing back and forth between the portion b and its vicinity, thereby reducing fuel consumption and reducing NO.
x has also been reduced. FIG. 18 shows the injection rate according to the change in the cam angle. FIG. 16 shows three injection rate patterns when the injection timing in FIG. 16 is a part b and a part, and is ideal.

[0005]

As described above, in the conventional variable pre-stroke fuel injection system, the injection timing is changed back and forth between the portion b and the vicinity thereof to reduce the fuel consumption and reduce the fuel consumption.
Although reduction of Ox has been attempted, in particular, sufficient reduction of NOx has not been obtained, and improvement is desired. That is, in the mode (including b1) in which the injection timing is changed back and forth in and around the portion b in FIG. 16, the oil feed rate proportional to the cam speed becomes uniformly high, and the broken line (in FIG. (BTDC 9.3 °), as shown in the example, the pressure in the injection pipe is relatively high at the pressure immediately before reaching the peak in the late stage of injection (shown as F range in FIG. 14).

For this reason, as shown by an example in FIG. 14 by a broken line h, the heat release rate is late (shown as H region in FIG. 14).
However, there was a problem that the peak was relatively high, and it was not possible to reduce NOx. Incidentally, in the conventional variable pre-stroke fuel injection device, the pre-angle Ap
The injection timing of FIG. 16 was used as part a by changing the injection timing. However, as shown in FIG. 18, the injection rate of the part a was advanced, but the injection rate was reduced. However, there is a problem in that the injection period becomes longer to inject the required amount of fuel, fuel efficiency and smoke are likely to be deteriorated, and the fuel injection and the smoke cannot be adopted in a multi-use operation range.

[0007] In consideration of these problems, it is clear that it is desirable to use the region b in order to suppress a decrease in fuel efficiency. It was confirmed that it is effective to reduce the initial oil supply rate (initial cam speed) in the variable pre-stroke fuel injection device. An object of the present invention is to provide a fuel injection control method and a variable pre-stroke fuel injection device that can reduce NOx without reducing fuel consumption.

[0008]

According to a first aspect of the present invention, there is provided a method according to the first aspect of the present invention, wherein a fuel oil supply rate according to a cam angle gradually rises in a first stage. A second-stage ascending portion which rises rapidly from the middle of the ascending stage;
Using a variable pre-stroke fuel injection device with a built-in concave cam that has an oil feed rate waveform that has a flat portion that becomes flat after the maximum value of the step rising portion and a falling portion that suddenly drops from the end of the flat portion, When the engine operating state is at least in the middle to high rotation range, the variable pre-stroke fuel is set such that the second stage rising portion immediately before the fuel supply rate flat portion becomes the injection start time and the flat portion becomes the injection end time. It is characterized by driving the injection device.

According to a second aspect of the present invention, in the fuel injection control method according to the first aspect, when the engine operation state is an idle operation state, the injection range is set immediately before the second-stage rising portion. I do.

According to a third aspect of the present invention, in the fuel injection control method according to the first aspect, the injection is started so that the injection amount ratio in the second stage rising portion immediately before the flat portion becomes 5 to 15%. It is characterized by controlling the timing.

According to a fourth aspect of the present invention, in the fuel injection control method according to the second aspect, the injection start timing is set at 10 degrees immediately before the cam angle of the second-stage ascending portion.

According to a fifth aspect of the present invention, there is provided a first-stage rising portion in which a fuel oil supply rate according to a cam angle gradually rises;
A second-stage rising portion that rises abruptly from the middle of the first-stage rising portion, a flat portion that becomes flat after the maximum value of the second-stage rising portion, and a descending portion that falls abruptly from the end of the flat portion. In the variable pre-stroke fuel injection device having a built-in concave cam having an oil feed rate waveform having an electronic timer for transmitting engine rotation to the concave cam, and control means for controlling the electronic timer, the control means includes: In accordance with the injection start timing, the electronic timer and the variable pre-stroke fuel device are drive-controlled at the optimal injection timing, so that at least the engine operation state is in the middle to high rotation range.
At the time, the above-mentioned two stages just before it becomes the flat part of the fuel oil transfer rate
The rising part is the injection start time, and the flat part is
The above electronic timer and variable press trolley will be
The fuel injection device is driven and controlled .

[0013]

[0014]

1 and 3 show a variable pre-stroke fuel injection device 1 according to an embodiment of the present invention. The variable pre-stroke fuel injection device 1 is mounted on an in-line six-cylinder diesel engine (hereinafter simply referred to as an engine), not shown, and the engine speed is reduced to half by a pump body 2 and a camshaft 3 in the body 2. The electronic timer 4 includes a transmitting electronic timer 4, a governor 5 that controls increase / decrease of the fuel injection amount, and a controller 6 that issues a drive output to each of the electromagnetic actuators of the electronic timer 4 and the governor 5.

The pump body 2 has a substantially box-shaped casing 201.
And a timer 4 at the bottom along the inside of the
The cam shaft 3 extending in the lateral direction is pivotally supported, and six pump portions 8 are sequentially arranged above the cam shaft 3 along the longitudinal direction of the shaft. Here, the cam shaft 3 is provided with a cam 9 for driving a plunger at a portion facing each pump portion 8. The six pump units 8 are each provided with a fuel injection valve 10 of a corresponding cylinder.
Linked to Here, each pump unit 8 has the same structure,
On the other hand, since the six cams 9 have the same shape except that the rotation phases are different, here, only one pump section 8 and one cam 9 will be mainly described.

As shown in FIG. 1, the pump section 8 has a cam 9 disposed at the center lower portion of the casing 201, and supports a roller-equipped tappet 11 at the upper end of the cam so as to be vertically movable. A return spring 12 and a plunger 13 abut on the upper portion of the tappet 11. The upper end of the return spring 12 is engaged with the projection on the inner wall of the casing 201 and constantly presses the tappet 11 against the cam 9. The upper part of the plunger 13 is inserted into upper and lower plunger barrels 14 and 15 supported by the casing 201, and the movable sleeve 16 is inserted particularly in the center. As shown in FIG. 4, the plunger 13 has a vertical hole 131 formed at the center thereof, and a slant groove 132 and a vertical groove 133 having an upper end communicating with the slant groove 132 and a lower end communicating with the vertical hole 131 on the peripheral surface. You.

On the other hand, the movable sleeve 16 has a spill port 161 on one side and a locking recess 162 on the other side. The governor 5 can rotate the timing rod 18 by the rotary solenoid 17 to slide the movable sleeve 16 up and down, and the control rod 19 arranged below the timing rod 18 is connected to one end by an electromagnetic actuator 21 connected to one end thereof. The plunger 13 is rotated by a sliding operation in the longitudinal direction. In addition, as shown in FIG. 3, the rotary solenoid 17 and the electromagnetic actuator 21 are connected to the control unit 6.

Here, when the timing rod 18 is slid up and down, the timing at which the lower end of the vertical groove 133 of the plunger 13 is closed to the lower end of the movable sleeve 16 can be adjusted back and forth, and the lift operation of the plunger 13 before the closing is performed. The stroke is pre-stroke, and fuel injection is performed by the lift operation after closing, and the injection timing is adjusted. On the other hand, plunger 13
Is rotated, the spill port 161 of the movable sleeve 16 is rotated.
Can be changed before and after the time of facing the inclined groove 132, and the injection amount can be adjusted. The electronic timer 4 receives the crank rotation of an engine (not shown) at a speed shifted by で, adjusts the rotation angle of the input rotation, and outputs the adjusted rotation to the camshaft 3.
Actuator 2 for adjusting the built-in rotation angle
2 operates according to the output of the controller 6, whereby the engine rotation can be advanced and retarded and transmitted to the camshaft 3.

The cam 9 of the pump section 8 is set so as to obtain a specific oil supply rate waveform as shown in FIG. That is,
According to the rotation of the cam 9, the plunger 13
The lift operation is performed, and the oil supply rate generated in response to the lift operation increases the first-stage rising portion E1 and the first-stage rising portion E that gradually increase.
The second-stage rising portion E2 which rises rapidly from the middle of Step 1, the flat portion E4 which becomes flat after the maximum value of the second-stage rising portion E2, and the descending portion E4 which falls sharply from the end of the flat portion.
Are set so as to change sequentially.

In order to ensure such an oil feed rate waveform, the cam 9 is formed as a concave cam, rotates left in FIG. 2, and has a base circle r1 and a lift circle r2. In particular, the lift ratio of the lift circle r2 of the cam 9 from the base circle r1 is greatly different between the former stage and the latter stage, that is, the low lift start region r following the base circle r1.
In contrast to 2-1, the subsequent high lift region r2-2 has a shape in which the protrusion ratio is greatly increased. When such a cam 9 drives the pump section 8, high-pressure fuel is supplied to the fuel injection valve 10 of the corresponding cylinder along the characteristic oil supply rate waveform shown by the solid line in FIG. The injection is sprayed into the combustion chamber of the corresponding cylinder. At this time, FIG.
At the point e1 at the second stage rising portion E2.
The pre-stroke s3 is set so that the injection is performed using (cam angle α1) as the injection start timing, and the injection in the initial injection range C1 is performed until the injection reaches the flat portion E3. The control of the pre-stroke s3 here is executed by the governor 5.

Further, the main injection region C2 in the flat portion E3 continues to a point e2 (cam angle α2) at which the injection ends, and the injection amount is adjusted at this point e2, and the point at which the injection ends. The control of e2 is executed by the governor 5. Here, the initial injection range C1 from the point e1 of the second-stage rising portion E2 and the main injection range C2 in the flat portion E3 are selected and set, for example, after performing the following data collection. . Here, as shown in FIG. 7, an engine whose NOx amount is adjusted to be constant at an engine speed of 1320 rpm is driven. At this time, the initial injection region C1 and the main injection region C2 are driven.
Were operated sequentially shifted along the cam angle.

Here, as shown in FIGS. 8 to 13, the injection start timing (cam angle α1) is set at six different positions, and the initial injection at each of the points p1 to p6 corresponding to FIGS. The rate mm ³ / deg and the fuel efficiency BFSC at that time were sampled, and based on this, the characteristic diagram of FIG. 7 was obtained. In FIG. 7, the point p3 at which the fuel economy B.S.F.C.
To p5 (see FIGS. 10 to 12), the initial injection range C1 is 5% to 15%, and the main injection range C2 is 85% to 95%.
% Operating range. Considering this point, 2
At each operation, the initial injection range C1 from the point e1 (cam angle α1) of the stepped rising portion E2 is set to 5% to 15%, and the main injection range C2 at the flat portion E3 is set to 85% to 95%. , The initial injection region C1 and the main injection region C2 are set, and the governor 5 is controlled during each injection control such that the injection start timing (point e1) and the injection end timing (point e2) of the second stage rising portion E2 are ensured. Is driven and controlled.

By setting the initial injection zone C1 and the main injection zone C2 in this manner, as shown in FIG. 6, the injection rate of the fuel injection valve 10 can be changed to the initial injection zone C1 and the main injection zone C2.
It is possible to obtain the injection rate pattern composed of the areas corresponding to C1 and C2 corresponding to the above. This injection rate pattern is similar to the ideal injection rate pattern described with reference to FIG. The pump section 8 moves through the rotary sleeve 17 via the rotary solenoid 17 so that the lower end of the vertical groove 133 of the plunger 13 is closed by the lower end of the movable sleeve 16 at the cam angle α1.
Is further driven, and at the cam angle α2, the spill port 161 of the movable sleeve 16 is connected to the inclined groove 132 of the plunger.
The injection amount can be adjusted by controlling the rotation angle of the plunger 13 via the electromagnetic actuator 21 so as to face the controller. The rotary solenoid 17 and the electromagnetic actuator 21 are connected to the controller 6 via drive circuits 26 and 27.

The controller 6 is an electronic control device. The main part of the controller 6 has a well-known hardware configuration equipped with a microcomputer. A rotation sensor 23 that outputs a signal used for calculating the rotation speed Ne, a load sensor 24 that detects an engine load Lθ signal, a water temperature sensor 25 that detects a water temperature signal wt, and the like are connected to each other. On the other hand, a rotary solenoid 17, an electromagnetic actuator 21, and a timer actuator 22 in the governor are connected to output ports (not shown) via drive circuits 26, 27, and 28. When such an engine is driven, the controller 6 controls the drive of the electronic timer at the optimal injection timing (injection start timing),
Governor for optimal injection amount and optimal injection mode (injection cam angle)
Drive with

Here, when the engine operating state is at the time of starting and at the time of idling, the optimal injection mode (injection cam angle) is changed to the D region (cam angle α3 to
α4), the movable sleeve 16 is slid up and down via a rotary solenoid 17 in the governor to use the same target area, and the plunger 13 is rotated via an electromagnetic actuator 21 to obtain a D area (cam angle α3 to α4). In this case, a cam angle of 10 degrees immediately before the second-stage rising portion E2 is secured, and the injection is performed at the optimum oil supply rate. In this case, the generation of idle noise can be reduced because of the low oil feed rate. It is sufficient that this region D is just before the second-stage rising portion E2 in the cam angle, and in some cases, the cam angle may be set to about 10 degrees.

On the other hand, when the engine operating state is in the middle to high rotation range, the optimum injection mode (injection cam angle) is changed to the C1 region (E2 portion in FIG. 5) of the second stage rising portion (E2 portion in FIG. 5) with a relatively low oil feed rate. The movable sleeve 16 is slid up and down via the rotary solenoid 17 in the governor so as to use the cam angles α1 to α4) and the C2 region (cam angles α4 to α2) of the flat portion (E3 portion in FIG. 5) that follows. Then, the plunger 13 is rotated via the electromagnetic actuator 21 so that the target cam angles α1 to
The C1 and C2 regions of α2 are secured, and injection is performed at the optimum oil supply rate. In this case, in the low oil feed rate C1 region, the total injection amount is 5%.
% To 15%, the initial injection rate is suppressed, and since the beginning of injection is gentle, the generation of NOx can be suppressed.
In the subsequent main injection region C2 with a high injection rate, 85% to 9% of the total injection amount.
Injection of 5% is performed, and the securing of output is achieved.

In this case, in particular, by changing the oil feed rate by two stages in the first and second stages in the engine operating state in the middle to high rotation range,
As shown in FIG. 6, the injection rate approaches the ideal injection pattern. As a result, as shown in FIG. 14, the injection characteristics to which the present invention is applied are, as shown by the solid line, compared with the conventional device shown by the broken line (using a high rate, high injection range). , And the heat release rate also peaked later. As a result, the peak heat release rate is reduced,
NOx can be reduced without reducing fuel consumption, or
When NOx is kept constant, the advance angle can be advanced by about 1 deg by the electronic timer, and the fuel efficiency can be improved. It should be noted that, in the initial injection region indicated by the reference character G in FIG.
The injection pressure rise rate MPa / deg (per crank angle) as shown in FIG.

As is clear from the above, in the initial injection region G, the injection characteristic of the apparatus to which the present invention is applied is as shown by the solid line m, and the pressure rise rate is more gradual than that of the conventional apparatus shown by the broken line n. It turned out that it was formed, and it was also clear from this point that NOx could be reduced. Further, in the variable pre-stroke fuel injection device of FIG. 1, the injection range (D range) of the low fuel supply rate immediately before the second-stage ascending portion E2 during the idling operation.
Is used, the initial injection rate can be kept low to reduce noise during idling operation.

Further, here, the injection amount ratio in the second stage rising portion E2 immediately before the flat portion E3 becomes 5 to 15%
In this case, the initial injection rate is surely reduced to suppress the generation of NOx, and the flat portion E3 is 95 to 85%, so that the high oil supply rate is reliably maintained in the latter period, so that a reduction in fuel efficiency can be reliably prevented. Further, here, the injection range of the low fuel oil supply rate of 10 degrees immediately before the cam angle of the second-stage ascending portion E2 at the time of idling operation is used, so that the initial injection rate can be kept low and the noise during idling operation can be reduced. .

Further, the variable pre-stroke fuel injection device 1 includes an electronic timer 4 for transmitting the engine rotation to the concave cam, and a controller 6 for controlling the electronic timer. In the range, the second-stage rising portion E2 immediately before the fuel oil transfer rate becomes the flat portion E3 is set as the injection start timing, and the flat portion E3
Since the electronic timer 4 is drive-controlled so that the fuel injection end timing is reached, the initial injection rate can be reduced to suppress the generation of NOx, and the high oil feed rate can be maintained in the latter period, so that a reduction in fuel efficiency can be prevented.

[0031]

According to the first aspect of the present invention, a concave cam having a first-stage ascending portion, a second-stage ascending portion, a flat portion, and a descending portion has a fuel oil supply rate according to a cam angle. When at least in the middle to high rotation range, the injection device is driven with the second stage rising portion as the injection start timing and the flat portion as the injection end timing. As described above, in particular, since the fuel supply rate is set so that the second rising portion is the injection start timing and the flat portion is the injection end timing, it is possible to reduce the initial injection rate and suppress the generation of NOx. As well as maintaining a high oil supply rate in the latter period, it is possible to prevent a decrease in fuel efficiency.

According to the fifth aspect of the present invention, the concave cam having a first-stage ascending portion, a second-stage ascending portion, a flat portion, and a descending portion having a fuel oil supply rate according to the cam angle is incorporated. The variable pre-stroke fuel injection device includes an electronic timer and control means for controlling the electronic timer. The control means drives and controls the electronic timer and the variable pre-stroke fuel injection device at an optimum injection timing according to the injection start timing. . Thus, in particular, the electronic timer that transmits the engine rotation to the concave cam, and the electronic timer and the control means that controls the variable pre-stroke fuel injection device are provided. Since the drive control of the pre-stroke fuel injection device is performed at the optimum injection timing, it is possible to suppress the generation of NOx and prevent a reduction in fuel efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pump body used in a variable pre-stroke fuel injection device as one embodiment of the present invention.

FIG. 2 is an enlarged side view of a cam in the pump main body of FIG. 1;

FIG. 3 is a schematic configuration diagram of the fuel injection device of FIG. 1;

FIG. 4 is an explanatory diagram of functions in a governor of the fuel injection device of FIG. 1;

FIG. 5 is a diagram of an oil feed rate pattern of the fuel injection device of FIG. 1;

FIG. 6 is a diagram of an injection rate pattern of the fuel injection device of FIG. 1;

FIG. 7 is a characteristic diagram of each oil feed rate-fuel efficiency when the injection rate according to the cam angle of the fuel injection device of FIG. 1 is changed by a plurality (p1 to p6).

8 is an oil feed rate-fuel efficiency characteristic diagram used in determining the p1 position in FIG. 7;

9 is an oil feed rate-fuel efficiency characteristic diagram used in determining the p2 position in FIG.

10 is an oil feed rate-fuel efficiency characteristic diagram used in determining the p3 position in FIG. 7;

FIG. 11 is an oil feed rate-fuel efficiency characteristic diagram used in determining the p4 position in FIG. 7;

12 is an oil feed rate-fuel efficiency characteristic diagram used in determining the position p5 in FIG. 7;

13 is an oil feed rate-fuel efficiency characteristic diagram used in determining the position p6 in FIG. 7;

14 is a characteristic diagram of pipe internal pressure per crank angle and thermal efficiency of the fuel injection device of FIG. 1;

FIG. 15 is a characteristic diagram of the injection pressure increase rate in a G region in FIG.

FIG. 16 is a characteristic diagram of cam lift and cam speed per cam angle in a conventional fuel injection device.

FIG. 17 is a side view of a cam used in a conventional fuel injection device.

FIG. 18 is a characteristic diagram of an injection rate per cam angle in the fuel injection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable pre-stroke fuel injection device 2 Pump main body 3 Cam shaft 4 Electronic timer 5 Governor 6 Controller 8 Pump unit 9 Cam 10 Fuel injection valve 13 Plunger 16 Movable sleeve 161 Spill port 17 Rotary solenoid 18 Timing rod 19 Control rod 21 Electromagnetic actuator 22 Actuator for timer e1 Injection start timing r1 Base circle r2 Lift circle r2-1 Low lift start area r2-2 High lift area s3 Prestroke C1 Initial injection area C2 Main injection area E1 First-stage rising portion E2 Second-stage rising portion E3 flat part E4 descending part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 1/02

Claims (5)

(57) [Claims] A first stage rising portion in which a fuel oil transfer rate according to a cam angle gradually rises; a second stage rising portion which rises sharply in the middle of the first stage rising portion; Using a variable pre-stroke fuel injection device with a built-in concave cam that has an oil feed rate waveform that has a flat portion that becomes flat after the maximum value of the step rising portion and a falling portion that suddenly drops from the end of the flat portion, When the engine operating state is at least in the middle to high rotation range, the variable pre-stroke fuel is set such that the second stage rising portion immediately before the fuel supply rate flat portion becomes the injection start time and the flat portion becomes the injection end time. A fuel injection control method for driving an injection device. 2. The fuel injection control method according to claim 1, wherein when the engine operation state is an idle operation state, an injection range is set immediately before the second-stage rising portion. 3. The fuel injection control according to claim 1, wherein the injection start timing is controlled so that the injection amount ratio in the second stage rising portion immediately before the flat portion becomes 5 to 15%. Method. 4. The fuel injection control method according to claim 2, wherein an injection start timing is 10 degrees immediately before the cam angle of the second rising portion. 5. A first-stage rising portion in which a fuel oil transfer rate according to a cam angle rises gently, a second-stage rising portion that rises sharply in the middle of the first-stage rising portion, and In the variable pre-stroke fuel injection device having a built-in concave cam having an oil feed rate waveform having a flat portion that becomes flat after the maximum value of the step rising portion and a falling portion that suddenly drops from the flat portion end, An electronic timer for transmitting engine rotation to the concave cam, and control means for controlling the electronic timer, wherein the control means sets the electronic timer and the variable pre-stroke fuel injection device to an optimum injection timing in accordance with the injection start timing. Drive control and at least
When the engine operating condition is of medium to high speed range also, above Symbol fuel oil feed rate
At the start of injection of the above-mentioned second-stage ascending part immediately before becoming a flat part
So that the flat part is the injection end time
Drives electronic timer and variable prestroke fuel injector
A variable pre-stroke fuel injection device characterized by controlling .