JP2623537B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

The present invention relates to a fuel injection control device for an internal combustion engine.

[Prior Art] A fuel injection valve is connected to a fuel supply pump via a fuel supply passage, a pressure accumulation chamber is provided in the fuel supply passage, and fuel accumulated in the pressure accumulation chamber is injected from the fuel injection valve by the fuel supply pump. Such a diesel engine is known (see, for example, US Pat. No. 3,875,547). In this diesel engine, the fuel injection timing and the fuel injection amount are controlled according to the operating state of the engine.

Further, the fuel injection timing and the fuel injection amount are controlled, and the pressure in the accumulator is controlled in accordance with the operating state of the fuel supply pump so that the discharge can be controlled. A device for improving the consumption has also been proposed (Japanese Patent Application No. 60-138990).

[Problems to be Solved by the Invention] Such a conventional fuel injection control device for an internal combustion engine is excellent in that the pressure in the accumulator is controlled in accordance with the operating state and optimum fuel injection is performed. There was a problem as follows.

(1) By the fuel supply pump capable of controlling the discharge pressure,
In order to control the pressure of the fuel supplied to the fuel supply passage from a high pressure required during high load operation to a low pressure required during low load operation, the motor that drives the fuel supply pump must be large. I had to. For this reason, power consumption is increased and responsiveness is reduced, so that the pressure may not always be controlled to the set pressure during the acceleration operation.

(2) The fuel supply pump capable of controlling the discharge pressure in the fuel injection control device of the internal combustion engine has a complicated configuration for controlling the discharge pressure, and thus has a problem that the entire device becomes large.

Therefore, an object of the present invention is to solve the above problems and to provide a small and responsive internal combustion engine fuel injection control device.

Configuration of the Invention [Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration as means for solving the problems. That is, the fuel supply passage M1 having a pressure accumulation chamber for storing high-pressure fuel.
A high-pressure fuel stored in the accumulator is injected into the combustion chamber by a desired injection amount at a desired injection timing. And a fuel supply pump M3 connected to the fuel supply passage M1 for supplying fuel from the fuel tank M4 to the fuel supply passage M1.
The fuel supply pump M3 is located on the upstream side of the fuel supply pump M3 with respect to the flow of fuel in a pipe communicating the fuel tank M4, and adjusts the flow rate of the fuel flowing into the fuel supply pump M3. A flow control valve M5, a pressure detecting means M6 for detecting a fuel pressure in the fuel supply passage M1, an operating state detecting means M8 for detecting an operating state of the engine M7, and a detection result of the operating state detecting means M8. Pressure setting means for setting the target pressure of the fuel in the fuel supply passage M1
M9, and the flow rate of the fuel supplied to the fuel supply pump M3 so that the fuel pressure in the fuel supply passage M1 detected by the pressure detection means M6 becomes the target pressure set by the pressure setting means M9. And a pressure control means M10 for controlling the fuel pressure in the fuel supply passage M1 by adjusting the flow rate with the flow control valve M5.

The flow control valve may be one that adjusts the flow rate by, for example, changing the cross-sectional area of the flow path, or one that adjusts the flow rate by opening and closing the valve by duty control.

In addition, the operating state detection means, as the operating state, for example,
As long as it detects the engine speed, the intake air pressure, the accelerator pedal depression amount, the intake air amount, the cooling water temperature, and the like as required, it is sufficient.

[Operation] The fuel injection control device for an internal combustion engine according to the present invention having the above-described configuration is configured such that the fuel supplied from the fuel tank M4 through the flow control valve M5 is supplied by the fuel supply pump M3 to the fuel supply passage M1 having an accumulator.
And the pressure control means.
The flow control valve M5 is controlled by M10 based on the detection result of the pressure detecting means M6 so that the pressure in the fuel supply passage M1 is set to the target pressure set by the pressure setting means M9. The target pressure is a target injection pressure in the operating state. That is, high-pressure fuel controlled to the injection pressure is stored in the fuel supply passage M1, and the fuel is supplied to the injection pressure by the opening control of the electronically controlled fuel injection valve M2 connected to the fuel supply passage M1. Is injected into the combustion chamber of the engine M7. The valve opening timing and the valve opening period of the electronically controlled fuel injection valve M2 are controlled, whereby the injection timing and the injection amount are controlled.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram of a fuel injection control device for a diesel engine according to one embodiment of the present invention, and FIG. 3 is a sectional view of the diesel engine. This diesel engine has a diesel engine body 1, a cylinder block 2, a cylinder head 3,
Piston 4, fuel chamber 5, intake valve 6, exhaust valve 7, combustion chamber 5
A fuel injection valve 8 and an intake manifold 9 are provided therein, and an inlet of the intake manifold 9 is connected to a supercharger T. The fuel injection valve 8 is connected via a fuel supply pipe 10 to a fuel accumulator pipe 11 common to each cylinder. The fuel pressure accumulating tube 11 has a pressure accumulating chamber 12 with a constant volume therein, and the fuel in the pressure accumulating chamber 12 is supplied to the fuel injection valve 8 through the fuel supply pipe 10. On the other hand, the pressure accumulating chamber 12 is connected to a discharge port of a supply pump 14 via a fuel supply pipe 13. The suction port of the fuel supply pump 14 is connected to the discharge port of the auxiliary fuel pump 16 via the flow control valve 15,
The suction port of the auxiliary fuel pump 16 is connected to the fuel reservoir tank 17
Linked to Each fuel injection valve 8 is connected to a fuel return conduit 18.
Is connected to the fuel reserve tank 17 via the. The auxiliary fuel pump 16 is provided to feed the fuel in the fuel reserve tank 17 into the fuel supply pump 14, and when the fuel can be sucked into the fuel supply pump 14 without the auxiliary fuel pump 16. It is not necessary to provide the auxiliary fuel pump 16 in particular. On the other hand, the fuel supply pump 14 is provided for discharging high-pressure fuel, and the high-pressure fuel discharged from the fuel supply pump 14 is accumulated in the pressure accumulating chamber 12.

Next, the fuel injection valve 8 will be described with reference to FIG. The fuel injection valve 8 is an electronically controlled fuel injection valve with a driving device having a piezoelectric element described later. FIG.
FIG. 2 is a sectional view of a fuel injection valve 8. The fuel injection valve includes a fuel injection valve main body 20, a nozzle 22 having a nozzle hole 21, a spacer 23, a nozzle holder 24 for fixing the nozzle 22 and the spacer 23 to the fuel injection valve main body 20, and a screw on the fuel injection valve main body 20. And a connection member 25 and the like in which a fuel inlet 25a is formed.

A control rod 26 slidably inserted in the axial direction is provided in the fuel injection valve body 20, and the nozzle 22 and the spacer
A pressure pin is also inserted in 23 to be slidable in the axial direction.
25 and a needle 28 are each arranged in series. Above the control rod 26, a fuel chamber 29 is formed. The fuel chamber 29 is connected to the pressure accumulating chamber 12 through the fuel inlet 25a and the fuel supply pipe 10.
(FIG. 3). Therefore, the fuel chamber 29 has a pressure accumulation chamber
The fuel pressure in the fuel chamber 29 acts on the upper surface of the control rod 26. The needle 28 has a conical pressure receiving surface 30, and a needle pressurizing chamber 31 is formed around the pressure receiving surface 30. The needle pressurizing chamber 31 is connected to the fuel chamber 29 via a fuel passage 32 on the one hand, and the needle 28
Nozzle hole through annular fuel passage 33 formed around
Connected to 21. A compression spring 34 that urges the pressure pin 27 downward is inserted into the fuel injection valve
The compression spring 28 is pressed downward by the compression spring 34. The control rod 26 has a conical pressure receiving surface 35 at an intermediate portion thereof, and a control rod pressurizing chamber 36 is formed around the pressure receiving surface 35.
The pressurizing chamber 36 is a cylinder 37 formed in the fuel injection valve body 20.
A hydraulic piston 38 is slidably inserted into the cylinder 37. An O-ring 39 is attached to the hydraulic piston 38.

On the other hand, a drive device 40 for driving the hydraulic piston 38 is attached to the fuel injection valve body 20. The driving device 40 includes a casing 41 fixed to the fuel injection valve body 20, and a piezoelectric element inserted between the piston 38 and the casing 40.
It consists of 42. The piezoelectric element has a laminated structure in which a number of thin plate-shaped piezoelectric elements are stacked, and when a voltage is applied to the piezoelectric element, the piezoelectric element causes longitudinal distortion due to an electrostrictive effect. That is, it extends in the longitudinal direction. Although the elongation amount is as small as, for example, about 50 μm, the responsiveness is extremely good, and the response time from application of a voltage to elongation is about 80 μsec. When the voltage is removed, the piezoelectric element 42 contracts immediately. As shown in FIG. 4, a disc spring 43 is provided between the hydraulic piston 38 and the fuel injection valve body 20.
Is inserted, and the hydraulic piston 38 is pressed toward the piezoelectric element 42 by the spring force of the disc spring 43. As shown in FIG. 5, a fuel passage 44 is formed in the hydraulic piston 38, and a check valve 45 is inserted into the fuel passage 44. Fuel is circulated between the casing 41 and the piezoelectric element 42 by a device (not shown) to cool the piezoelectric element 42, and when the fuel in the control rod pressurizing chamber 36 leaks, the fuel in the casing 41 passes through the fuel passage 44. And, it is supplied into the control rod pressurizing chamber 36 via the check valve 45.

When the fuel in the control rod pressurizing chamber 36 is not pressurized, the needle 28 has a downward force acting on the upper surface of the control rod 26, a downward force by the compression spring 34, and a needle 28.
An upward force acting on the pressure receiving surface 30 of the second member is applied. At this time, the diameter of the control rod 26, the spring force of the compression spring 34, and the area of the pressure receiving surface 30 of the needle 28 are set so that the total of the downward force is slightly larger than the upward force. Therefore, a downward force acts on the normal needle 28, and thus the normal needle 28 closes the nozzle hole 21. Next, when a voltage is applied to the piezoelectric element 42, the hydraulic piston 38 moves to the left in the drawing because the piezoelectric element 42 expands, and as a result, the pressure in the control rod pressurizing chamber 36 increases. At this time, the control rod 26 rises because an upward force acts on the pressure receiving surface 35 of the control rod 26, and thus the needle 28 rises, so that fuel is injected from the nozzle hole 21. The response at this time is about 80 μsec as described above, which is extremely fast. On the other hand, when the voltage to the piezoelectric element 42 is removed, the piezoelectric element 42 contracts, and as a result, the fuel pressure in the control rod pressurizing chamber 36 decreases, so that the control rod 26 and the needle 28 descend and the fuel injection stops. I'm sullen. The responsiveness at this time
It is very fast, about 80 μsec. As described above, when the fuel in the control rod pressurizing chamber 36 is not pressurized, the sum of the downward force acting on the needle 28 is slightly larger than the upward force, so that the diameter of the control rod 26 is The spring force of the compression spring 34 and the area of the pressure receiving surface 30 of the needle 28 are determined. Therefore, if a small upward force is applied to the pressure receiving surface 35 of the control rod 26, the needle 28 can be raised. That is, the fuel pressure in the control rod pressurizing chamber 36 to be raised in order to raise the needle 28 can be small, and thus the electric power to be applied to the piezoelectric element 42 can be small.

FIG. 6 shows an example of the fuel supply pump 14 capable of controlling the discharge pressure. Referring to FIG. 6, a fuel supply pump 14 includes a fixed shaft 51 fixedly supported by a pump casing 50, and a fixed shaft 51.
Rotating rotor 52, bearing 53 on pump casing 50
And a ring 54 rotatably supported through the ring.
A large number of radial pistons 55 arranged radially are arranged on the rotor 52, and a shoe 56 that rotates together with the radial piston 55 is inserted between each radial piston 55 and the ring 54. When the rotor 52 rotates, the radial piston 55 also rotates. At this time, the shoe 56 slides on the inner peripheral surface of the ring 54, and the ring 54 also rotates by the frictional force with the shoe 56. A suction port 57 and a discharge port 58 are formed in the fixed shaft 51, and the suction port 57 is provided with the flow control valve 15 (FIG. 2).
The discharge port 60 is connected to the pressure accumulating chamber 12 (FIG. 2).
The cylinder chamber 59 of each radial piston 55 communicates with a suction port 57 and a discharge port 58 alternately. When the cylinder chamber 59 communicates with the suction port 57, fuel is sucked into the cylinder chamber 59 because the radial piston 55 moves radially outward, and is compressed when the cylinder chamber 59 communicates with the discharge port 58. Fuel is discharged from the cylinder chamber 59 to the discharge port 58.

Next, the flow regulating valve 15 will be described with reference to FIG. FIG. 7 is a sectional view of the flow control valve 15. The flow regulating valve 15 is a valve body 60, a valve casing 61 attached to the valve body 60, a pulse motor 62 attached to the valve casing 61, and rotatably supported by the valve casing 61 and rotated by the pulse motor 62. A plunger 63 is provided. The valve body 60 is provided with an inflow hole 64 communicating with the fuel pump 16 and an outflow hole 65 communicating with the fuel supply pump 14.
Further, an inclined portion 66 inclined in the axial direction is formed at the center of the plunger 63, and the plunger 63 is
A fuel hole 67 is drilled toward the lower end of 63. A fuel hole 68 is formed in the valve casing 61 at a position corresponding to the inclined portion 66, and the other end of the fuel hole 68 communicates with the inflow port 64. Also,
A fuel hole 69 is formed in a lower portion of the valve casing 61, and the fuel hole 69 communicates the fuel hole 67 with the outlet 65.

The flow regulating valve 15 is adapted to generate a predetermined pulse from a pulse motor 62.
, The plunger 63 is rotated at a rotation angle corresponding to the pulse. Therefore, as shown in FIG.
When the 63 is rotated in the direction of arrow a, the inclined portion 66 also rotates in the direction of arrow a, the opening area of the fuel hole 68 increases, and when the plunger 63 is rotated in the direction of arrow b, the inclined portion 66 also rotates in the direction of arrow b.
The opening area of the fuel hole 68 is reduced. Therefore, the fuel that has flowed into the inflow port 64 passes through the fuel hole 68, is throttled to a flow rate corresponding to the position of the inclined portion 66, and reaches the outflow port 65 through the fuel holes 67 and 69. As described above, the flow regulating valve 15 is
The flow rate of the fuel passing through the flow rate control valve 15 can be adjusted by inputting a predetermined pulse to the control unit.

Although the fuel supply system of the diesel engine has been described in detail above, the fuel supplied to the pressure accumulating chamber 12 pressurized by the fuel supply pump 14 is controlled by an electronic control circuit 70 to be described later. 8 directly into the cylinder. In order to perform such control by the electronic control circuit 70, as shown in FIGS. 2 and 3, the diesel engine is provided with various sensors for detecting the operation state and the like.

First, a fuel pressure sensor 75 for detecting a fuel pressure in the pressure accumulating chamber 12 is attached to an end of the fuel pressure accumulating pipe 11. The fuel pressure sensor 75 generates an output voltage proportional to the fuel pressure in the accumulator 12. On the other hand, a supercharging pressure sensor 76 for detecting a supercharging pressure in the intake manifold 9 is mounted in the intake manifold 9. The supercharging pressure sensor 76 generates an output voltage proportional to the pressure in the intake manifold 9. Further, a water temperature sensor 77 for detecting an engine cooling water temperature is attached to the engine body 1. Water temperature sensor 77 generates an output voltage proportional to the engine cooling water temperature. Further, the accelerator pedal 78 has an accelerator pedal.
Load sensor that generates an output voltage proportional to the amount of depression of 78
79 is installed. A pair of disks 81, 82 are mounted on the engine crankshaft 80, and these disks 81, 82
A pair of crank angle sensors 83 and 84 facing the toothed outer peripheral surface of
Is arranged. One of the crank angle sensors 83 generates an output pulse indicating, for example, that the first cylinder is at the intake top dead center. Therefore, from the output pulse of the crank angle sensor 83, it is determined which cylinder the fuel injection valve 8 should be operated. Can be determined. The other crank angle sensor 84 generates an output pulse every time the crankshaft 80 rotates by a certain angle, and therefore the engine speed can be calculated from the output pulse of the crank angle sensor 84.

Next, the electric system of this embodiment will be described with reference to FIG. As shown in FIG. 2, the electronic control circuit 70 is a well-known electronic control circuit.
An input / output circuit configured with the CPU 91, ROM 92, and RAM 93 as the center of a logical operation circuit and performing input / output with the outside, here, a motor drive output circuit 94, a valve drive output circuit 95, and a pulse input circuit
6, the analog input circuit 97 and the like are connected to each other via a common bus 98.

The CPU 91 receives signals from the crank angle sensors 83 and 84 via a pulse input circuit 96, and receives signals from a fuel pressure sensor 75, a supercharging pressure sensor 76, a water temperature sensor 77, and a load sensor 79 via an analog input circuit 97, Enter each.

Further, data such as a fuel injection amount at a predetermined load, a predetermined engine speed, an injection start timing at a load, a reference fuel pressure, and the like are written in the ROM 92 in advance.

C based on these signals and the data in ROM 92 and RAM 93
PU91 is a fuel supply pump 1 via a motor drive output circuit 94.
4. A drive signal is output to the flow control valve 15 and the fuel pump 16, and a drive signal is output to each fuel injection valve 8 via the valve drive circuit 95.

Next, the processing performed in the electronic control circuit 70 will be described with reference to the flowcharts of FIGS. 9 to 12 and the graph of FIG.

When the diesel engine starts operating, the fuel supply pump
The electronic fuel cell 14 is operated by the electronic control circuit 70 at half the engine speed, and the auxiliary fuel pump 16 is operated at a predetermined constant speed.

FIG. 9 shows a main routine, which is executed by interruption every predetermined crank angle. Referring to FIG. 9, first, at step 100, the output signal of the crank angle sensor 84 indicating the engine speed N and the load sensor 79 indicating the depression amount L of the accelerator pedal.
The output signal of the supercharging pressure sensor 76 representing the supercharging pressure B, the output signal of the water temperature sensor 77 representing the engine cooling water temperature T,
And a fuel pressure sensor 75 indicating the fuel pressure P in the accumulator chamber 12.
Are sequentially input into the CPU 91, and the engine speed N is calculated from the output signal of the crank angle sensor 84. The engine speed N, accelerator pedal depression amount L, supercharging pressure B, water temperature T, and fuel pressure P are stored in the RAM 93. Next, at step 200, the injection amount τ is calculated, at step 300, the injection timing is calculated, and at step 400, the fuel pressure P is controlled. The calculation of the injection amount τ in step 200 is shown in FIG. 10, the calculation of the injection timing in step 300 is shown in FIG. 11, and the control of the fuel pressure P in step 400 is shown in FIG.

FIG. 10 shows a flowchart for calculating the fuel injection amount τ. Referring to FIG. 10, first, step 20
In step 1, the basic fuel injection amount τ0 is calculated from the accelerator pedal depression amount, that is, the load L. FIG. 13 (a) shows the relationship between the basic fuel injection amount τ0 and the load L, and this relationship is stored in the ROM 92 in advance. Then step 202
Then, the supercharging correction coefficient K1 is calculated from the supercharging pressure P. As shown in FIG. 13 (b), the supercharging correction coefficient K1 increases as the supercharging pressure P increases. The relationship shown in FIG.
It is stored in the ROM 92. Next, at step 203, the injection amount τ = K1 · τ0 is calculated. Next, at step 204, the maximum injection amount MAX is calculated from the water temperature T. Fig. 13 (c)
Maximum injection amount MAX to prevent the generation of white smoke as shown in
Decreases as the water temperature T increases. Next, at step 205, it is determined whether or not the injection amount τ is larger than the maximum injection amount MAX. If τ> MAX, proceed to step 206 and τ
= MAX. Therefore, the maximum injection amount MAX is limited by the water temperature T.

FIG. 11 shows a flowchart for calculating the fuel injection period. Referring to FIG. 11, first, step 30
Injection start timing τa from engine speed N and load L at 1
Is calculated. As shown in FIG. 13 (d), the relationship between the injection start timings τ11... Τmn and the engine speed N and the load L is stored in the ROM 92 in advance in the form of a map. Is done. Next, at step 302, a water temperature correction coefficient K2 is calculated from the water temperature T. Water temperature correction coefficient
K2 decreases as the water temperature T increases as shown in FIG. 13 (f), and the relationship shown in FIG. 13 (f) is stored in the ROM 92 in advance. Next, at step 303, a supercharging correction coefficient K3 is calculated from the supercharging pressure P. The boost pressure correction coefficient K3 increases as the weekly boost pressure P increases, as shown in FIG.
The relationship shown in FIG. 13 (e) is stored in the ROM 92 in advance. Next, at step 304, the correction coefficients K2 and K3 are added to the injection start timing τa determined at step 301 to determine the actual injection start timing τa. Actual injection start timing τa
Increases as K2 and K3 increase. That is, it is accelerated. Next, at step 305, the injection completion time τb is calculated from the injection amount τ calculated in the routine shown in FIG. 10 and the actual injection start time τa. The injection start timing τa and the injection completion timing τb obtained in this way are
Are output to the valve drive output circuit 95 at τa · τ
The injection control of each fuel injection valve is performed according to b.

FIG. 12 shows a flowchart for controlling the fuel pressure P. Referring to FIG. 12, first of all, Step 40
In 1, it is calculated from the reference fuel pressure P0 from the engine speed N and the load L. As shown in FIG. 13 (g), the reference fuel pressure P11
.., Pmn and the relationship between the engine speed N and the load L are stored in advance in the ROM 92 in the form of a map, and the reference fuel pressure P0 is calculated from this map. Next, at step 402, a water temperature correction coefficient K4 is calculated from the water temperature T.

The water temperature correction coefficient K4 increases as the water temperature T increases as shown in FIG. 13 (h), and the relationship shown in FIG. 13 (h) is stored in the ROM 92 in advance. Then step 4
In 03, the supercharging pressure correction coefficient K5 is calculated from the supercharging pressure P. The supercharging pressure correction coefficient K5 increases as the supercharging pressure P increases as shown in FIG. 13 (i), and the relationship shown in FIG. 13 (i) is stored in the ROM 92 in advance.

Next, at step 404, the target reference fuel pressure P0, that is, the target fuel pressure P0 is determined by multiplying the reference fuel pressure P0 determined at step 401 by the correction coefficients K4 and K5. The target fuel pressure P0 increases as the water temperature T increases, and increases as the supercharging pressure P increases. Then step 405
Is determined whether the absolute value of the difference between the target fuel pressure P0 and the current fuel pressure P detected by the fuel pressure sensor 75 is smaller than a predetermined value ΔP. The value of ΔP is such a value that the pressure difference is small and it is determined that the fuel pressure P does not need to be changed. | P
If 0−P | ≧ ΔP, the routine proceeds to step 406, where it is determined whether or not P> P0. If P> P0, the process proceeds to step 407, in which the flow control valve 15 is driven to reduce the flow F. That is, the step motor 62 is driven via the motor drive output circuit 94, and the plunger 63 is rotated by a predetermined amount in the direction of arrow b (FIG. 8) to reduce the flow rate F. Accordingly, the flow rate flowing into the fuel supply pump 14 decreases, and the flow rate flowing out decreases accordingly, so that the fuel pressure in the accumulator 12 that supplies fuel to the fuel injection valve 8 immediately decreases. On the other hand, if P ≦ P0, step 40
Proceeding to 8, the flow control valve 15 is driven to increase the flow F. That is, the step motor 62 is driven to rotate the plunger 63 in the direction of arrow a (FIG. 8) by a predetermined amount to increase the flow rate F.
Therefore, the flow rate flowing into the fuel supply pump 14 increases, and accordingly, the flow rate flowing out also increases, and the fuel pressure in the accumulator 12 immediately increases. In step 405, | P0−P | <
When it is determined that ΔP, the processing routine is completed,
At this time, the step motor 66 is kept stationary. In this way, the fuel pressure P in the accumulator 12 is maintained at the target fuel pressure P0.

As described above, the fuel injection control device for the diesel engine according to the present embodiment adjusts the fuel flowing into the fuel supply pump 14 by the flow control valve 15 to increase or decrease the discharge amount from the fuel supply pump 14, and the fuel in the accumulator chamber 12. The pressure is controlled to a pressure according to the operating condition.

Therefore, according to the fuel injection control device for a diesel engine of the present embodiment, the fuel injected from the fuel injection valve 8 can be optimally controlled according to the operating state by controlling the fuel pressure in the accumulator 12. . As a result, the optimum fuel can be always secured regardless of the engine operating state, so that the generation of noise can be suppressed, and the output and fuel consumption can be improved. Further, with a simple configuration provided with the fuel adjusting valve 15, the pressure in the accumulator 12 can be controlled with good responsiveness without being affected by the responsiveness of the fuel supply pump 14. Also,
Since the fuel supply pump 14 does not require a large motor, the power consumption is reduced, and further, there is no need to provide a drive device for controlling the discharge pressure, and the entire device becomes compact.

The flow control valve 15 is not limited to the one shown in FIG.
14 and 16 may be used. The flow control valve shown in FIG. 14 controls the position of a plunger 504 having a tapered portion 503 at the tip by the action force of a solenoid 501 and a spring 502, and adjusts the flow as shown in FIG.
The flow control valve shown in FIG. 16 moves the poppet valve body 507 up and down by a solenoid 505 and a spring 506 to open and close the valve. This valve may be configured to adjust the flow rate by duty control of the opening and closing of the valve by the electronic control circuit 90.

The case where the present invention is applied to a diesel engine has been described as an embodiment of the present invention. However, the present invention is not limited to such an embodiment, and may be implemented in various modes without departing from the gist of the present invention. Of course you can.

Effect of the Invention As described in detail above, according to the fuel injection device for an internal combustion engine of the present invention, the fuel pressure in the fuel passage is controlled with good responsiveness, and the fuel injected from the fuel injection valve is optimally controlled according to the operation state. I do. As a result, an optimum fuel can be always secured irrespective of the operating state of the engine, and therefore, there is an effect that generation of noise can be suppressed, and output and fuel consumption can be improved. Further, there is an effect that the power consumption is small and the power consumption is small.

[Brief description of the drawings]

FIG. 1 is a block diagram of a fuel injection control device for an internal combustion engine, illustrating a basic configuration of the present invention. FIG. 2 is a schematic configuration diagram of a fuel injection control device for a diesel engine, showing one embodiment of the present invention. The figure is a sectional view of the diesel engine of the present embodiment,
FIG. 5 is a sectional view of the fuel injection valve of the present embodiment, FIG. 5 is an enlarged sectional view of the piston of FIG. 4, FIG. 6 is a sectional view of the fuel supply pump of the present embodiment, and FIG. FIG. 8 is an explanatory view of the operation of the plunger of FIG. 7, FIG. 9 is a flowchart showing a main routine performed in the present embodiment, and FIG. 10 is a flowchart showing calculation of the injection amount in the present embodiment. FIG. 11 is a flowchart for executing the calculation of the injection time of the present embodiment, FIG. 12 is a flowchart for executing the control of the fuel pressure of the present embodiment, and FIG. 13 is a correction coefficient. FIG. 14 is a cross-sectional view showing another embodiment of the flow regulating valve, FIG. 15 is an explanatory diagram of the operation of the plunger of FIG. 14, and FIG. 16 shows another embodiment of the flow regulating valve. It is sectional drawing. 1 Diesel engine body 8 Fuel injection valve 12 Accumulation chamber 14 Fuel supply pump 15 Flow control valve 70 Electronic control circuit 75 Fuel pressure sensor 76 Supercharging pressure sensor 77 … Water temperature sensor 79 …… Load sensor 83,84 …… Crank angle sensor

Claims (1)

(57) [Claims] A fuel supply passage having a pressure accumulating chamber for storing high-pressure fuel, a fuel supply passage communicating with the fuel supply passage, and a tip facing the combustion chamber; and a high-pressure fuel stored in the pressure accumulating chamber. An electronically controlled fuel injection valve that is controlled to inject a desired injection amount into the combustion chamber at a desired injection timing; and a fuel supply that is connected to the fuel supply passage and supplies fuel from the fuel tank to the fuel supply passage. A pump, and a flow control valve located upstream of the fuel supply pump with respect to a flow of fuel in a pipe connecting the fuel supply pump and the fuel tank, and adjusting a flow rate of fuel flowing into the fuel supply pump. Pressure detecting means for detecting a fuel pressure in the fuel supply passage; operating state detecting means for detecting an operating state of the engine; and a fuel supply passage based on a detection result of the operating state detecting means. Pressure setting means for setting a target pressure of the fuel in the fuel supply pump; and a fuel pressure in the fuel supply passage detected by the pressure detection means is set to the target pressure set by the pressure setting means. A fuel injection control device for an internal combustion engine, comprising: pressure control means for controlling a fuel pressure in the fuel supply passage by adjusting a flow rate of supplied fuel by the flow control valve.