JP2862123B2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device for an internal combustion engine suitable for injecting fuel into a diesel engine.

[0002]

2. Description of the Related Art Conventionally, in vehicles equipped with a diesel engine, a direct injection diesel engine for injecting fuel into a combustion chamber from a fuel injection valve provided in a cylinder head has been widely used. As shown in FIG. 6, the fuel injection valve has a nozzle 1 fixed to a cylinder head 2, and the position between the nozzle 1 and the piston 3 changes according to the movement of the piston 3.

[0003]

In the prior art, since the positions of the nozzle 1 and the piston 3 change according to the position of the piston 3, as shown in FIG. The fuel spray may come off the combustion chamber 4. Particularly at high speeds, the fuel often comes off the combustion chamber 4, and the emission of HC, graphite, etc. may increase significantly.

An object of the present invention is to provide a fuel injection device for an internal combustion engine that can inject fuel into a combustion chamber following the movement of a piston.

[0005]

In order to achieve the above object, the present invention provides an injection fuel reservoir formed in a cylinder head for storing injection fuel, an injection fuel reservoir formed in a cylinder head and a combustion chamber. And one end is closed and the other end is opened and inserted into the fuel injection reservoir, and a part of the through hole is slidably inserted into the through hole. A movable nozzle having an injection hole communicating with the combustion chamber formed therein, an injection fuel reservoir and an injection hole inserted into the movable nozzle, one end of which is fixed to the injection fuel reservoir, and the other end of which is formed in accordance with the movement of the movable nozzle. A fixed needle having a valve seat that opens and closes is formed, and the injection fuel reservoir is slidably mounted on the fixed needle to separate the interior of the injected fuel reservoir into a primary fuel chamber and a secondary fuel chamber, and the secondary fuel chamber is connected to a movable nozzle. Piston in the secondary fuel chamber of the injected fuel tank An elastic member that is inserted and acts on the piston to apply an urging force for closing the injection hole of the movable nozzle, and means for supplying high-pressure fuel to the primary fuel chamber and the secondary fuel chamber at a time and a period according to the operating state of the engine And a fuel injection device for an internal combustion engine in which a fuel passage communicating with the secondary fuel chamber and the injection hole of the movable nozzle is formed on the secondary fuel chamber side of the piston.

According to another aspect of the present invention, there is provided an injection fuel reservoir formed in a cylinder head for storing injected fuel, and a through hole formed in the cylinder head for connecting the injected fuel reservoir with a combustion chamber. And one end is closed and the other end is opened and inserted into the fuel injection reservoir, and a part thereof is slidably inserted into the through hole, and is closed to the combustion chamber at the closed end side. A movable nozzle having an injection hole communicating therewith, and a valve seat inserted into the injection fuel reservoir and the movable nozzle and having one end fixed to the injection fuel reservoir and opening and closing the injection hole at the other end according to the movement of the movable nozzle. And a piston which is slidably mounted on the fixed needle and separates the injected fuel reservoir into a primary fuel chamber and a secondary fuel chamber, and the secondary fuel chamber is connected to the movable nozzle. Inserted into the secondary fuel chamber of the injected fuel reservoir An elastic member that applies a biasing force to the piston to close the injection hole of the dynamic nozzle, a low-pressure tank that stores fuel, and a high-pressure tank that stores fuel from the low-pressure tank as fuel at a pressure corresponding to the engine speed. A first fuel passage connecting the primary fuel chamber of the injected fuel reservoir to the low-pressure tank, a second fuel passage connecting the secondary fuel chamber of the injected fuel reservoir to the low-pressure tank, and branching from the middle of the first fuel passage. A third fuel passage connected to the high-pressure tank, a fourth fuel passage branched from the middle of the second fuel passage and connected to the high-pressure tank, and a branch point between the first fuel passage and the third fuel passage. A first switching valve provided to switch a passage according to a command, a second switching valve provided at a branch point between a second fuel passage and a fourth fuel passage to switch a passage according to a command, and an engine speed. Speed sensor to detect A crank angle sensor for detecting a crank angle of emission, and the accelerator opening sensor,
A fuel injection amount calculating means for calculating a fuel injection amount based on a detection output of the rotation speed sensor and a detection output of the accelerator opening sensor, and a fuel injection amount calculating means in response to the detection output of the crank angle sensor during fuel injection. First time only for the time corresponding to the calculated value
Switching command means for instructing the switching valve and the second switching valve to switch from the low-pressure tank to the high-pressure tank; the secondary fuel chamber of the injected fuel reservoir and the movable nozzle A fuel injection device for an internal combustion engine, in which a fuel passage communicating with an injection hole is formed.

In configuring the fuel injection device, the fuel injection amount calculating means calculates a pilot fuel injection amount and a main fuel injection amount based on detection outputs of an engine speed sensor and an accelerator opening sensor. The switching command means responds to the detection output of the crank angle sensor at the time of pilot injection, and outputs the high pressure from the low pressure tank to the first switching valve and the second switching valve for a time corresponding to the value calculated by the fuel injection amount calculating means. In response to the detection output of the crank angle sensor, a command is issued to the first switching valve and the second switching valve for a time corresponding to the value calculated by the fuel injection amount calculating means during the subsequent main injection. It is desirable to be configured to instruct switching from the low pressure tank to the high pressure tank.

[0008]

According to the above-described means, when the fuel injection is commanded, the switching from the low pressure tank to the high pressure tank is commanded to the first switching valve and the second switching valve, and the fuel from the high pressure tank is injected. Sent to fuel reservoir. At this time, since the fuel at the pressure corresponding to the engine speed is stored in the high-pressure tank, the fuel at the pressure corresponding to the piston of the engine is supplied to the injected fuel reservoir. Then, when the piston in the injected fuel reservoir slides by the fuel from the high-pressure tank, the movable nozzle is moved to the combustion chamber side, and the fuel is injected from the injection hole. That is, as the piston of the engine moves downward, the movable nozzle moves toward the combustion chamber, and spray is performed into the combustion chamber. Therefore, it is possible to prevent fuel from being injected outside the combustion chamber even when the engine is operating at a high speed.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, an injection fuel reservoir 14 is formed in a cylinder head 12 of a diesel engine 10,
A cylinder head cover 16 is provided above the injection fuel reservoir 14.
Is fixed, and a through hole 2 communicating with the combustion chamber 18 is provided on the bottom side.
0 is formed. A cylindrical movable nozzle 22 is slidably inserted into the through hole 20. A fixed needle 24 is inserted into the injected fuel reservoir 14 and the movable nozzle 22, and the interior of the injected fuel reservoir 14 and the movable nozzle 22 are divided into two by the fixed needle 24. The fixed needle 24 has one end fixed to the cylinder head cover 16 and the other end formed with a valve seat 28 for opening and closing an injection hole 26 formed on the tip side of the movable nozzle 22. A piston 34 is slidably mounted on the fixed needle 24 and inserted into the injected fuel reservoir 14 and bisects the interior of the injected fuel reservoir 14 into a primary fuel chamber 30 and a secondary fuel chamber 32. The opening end side of the movable nozzle 22 is connected to the secondary fuel chamber side of the piston 34, and a fuel passage 36 connecting the secondary fuel chamber 32 and the injection hole 26 is formed. Further, a valve closing spring 38 as an elastic member is mounted in the secondary fuel chamber 32, and the piston 34 is moved toward the primary fuel chamber 30 by receiving an urging force from the spring 38. That is, the piston 34 is normally set in the primary fuel chamber 3 by the urging force of the valve closing spring 38.
By being urged to the zero side, the injection hole 26 is closed by the valve seat 28 of the fixed needle 24.

On the other hand, the primary fuel chamber 30 is provided in the first fuel passage 40
The secondary fuel chamber 32 is connected to the low-pressure tank 42 via a second fuel passage 44. In the middle of the first fuel passage 40, the third fuel passage 4
6 is branched and connected, and a fourth fuel passage 48 is branched and connected in the middle of the second fuel passage 44.
The third and fourth fuel passages 46 and 48 are connected to a high-pressure tank 50, respectively. Fuel from the low-pressure tank 42 is supplied to the high-pressure tank 50 via a pressure-up pump 52. The booster pump 52 supplies fuel having a pressure corresponding to the engine speed to the high-pressure tank 50.

The first fuel passage 40 and the third fuel passage 46
A three-way valve 54 as a first switching valve is provided at a branch point between the two, and a three-way valve 56 as a second switching valve is provided at a branch point between the second fuel passage 44 and the fourth fuel passage 48. ing. Each of the three-way valves 54, 56 switches the passage according to a command from the controller 58.

As shown in FIG. 2, the controller 58 includes an accelerator opening sensor 60 and an engine speed sensor 6.
2. Signals from a group of sensors for detecting various operating states of the engine 10, such as an intake pressure sensor 64, a coolant temperature sensor 66, and a crank angle sensor 68, are supplied. The controller 58 has a memory for an injection amount map determined from the engine speed, the injection amount, and the accelerator opening, and also has a memory for the injection timing map determined from the engine speed, the injection timing, and the accelerator opening. . The arithmetic unit 70 calculates the basic injection timing and the basic injection amount based on the signals from the accelerator opening sensor 60 and the engine speed sensor 62, and corrects the injection timing according to the signals from the intake pressure sensor 64 and the coolant temperature sensor 66. In addition, the injection amount is corrected. Further, the injection timing is set in accordance with the signal from the crank angle sensor 68, and the drive unit 72 outputs a drive signal to the three-way valves 54 and 56.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. First, signals from the cooling water temperature sensor 66, the accelerator opening sensor 60, the intake pressure sensor 64, and the engine speed sensor 62 are fetched (step 1).
0), the calculation unit 70 calculates the injection timing and the injection amount (step 12). After this, the crank angle sensor 68
Is read (step 14), and it is determined whether or not the crank angle is the injection timing (step 16). When the crank angle matches the injection timing, the drive unit 72 commands the three-way valves 54 and 56 to switch from the low pressure side to the high pressure side (step 18). That is, as shown in FIG. 4, before the injection is performed, the three-way valves 54 and 56 are switched to the low pressure side, the primary fuel chamber 30 and the secondary fuel chamber 32 are connected to the low pressure tank 42, respectively, and the valve is closed. The injection hole 26 is closed by the valve seat 28 by the urging force of the spring 38, but when the three-way valves 54 and 56 are switched to the high-pressure tank 50 side at the injection timing, the primary fuel chamber 30 and the secondary fuel chamber 32 are connected to the high-pressure tank 50, respectively. In this case, since the pressure receiving area of the piston 34 on the primary fuel chamber 30 side is larger than the pressure receiving area of the piston 34 on the secondary fuel chamber 32 side, the pressure of the primary fuel chamber 30 becomes higher than the pressure of the secondary fuel chamber 32. The pressure in the primary fuel chamber 30 is
When the force is higher than the urging force of the secondary fuel chamber 3
Move to side 2. Since the movable nozzle 22 moves toward the combustion chamber 18 with the movement of the piston 34, the valve seat 28
Is separated from the injection hole 26, and the fuel is injected from the injection hole 26.

While fuel is being injected from the injection hole 26,
The signal from the crank angle sensor 68 is read (step 20), and it is determined whether or not the crank angle has reached the injection end timing (step 22). When the crank angle reaches the injection end timing, the three-way valves 54 and 56 are instructed to switch from the high pressure side to the low pressure side (step 2).
4), the processing in this routine ends.

As described above, according to the present embodiment, the combustion chamber 18
When the piston inside moves downward, the movable nozzle 22 moves toward the combustion chamber 18 following the downward movement of the piston and fuel is injected from the injection hole 26.
Injection to the outside can be prevented, which can contribute to reduction of knock and combustion noise. Further, during high-speed rotation, the spray can be prevented from being injected out of the combustion chamber 18 even when the injection continues until late, such as when the injection timing is delayed or the injection hole 26 is throttled. Therefore, the injection timing can be delayed by narrowing the injection hole 26 without deteriorating the combustion.

As shown in FIG. 5, before the main injection,
By performing the pilot injection, the knock and the combustion noise can be further reduced.

[0017]

As described above, according to the present invention,
The movable nozzle is moved to the combustion chamber side according to the movement of the piston in the combustion chamber, preventing the spray from being injected outside the combustion chamber even when the injection continues late, such as by delaying the injection timing or narrowing the injection hole. The injection hole can be throttled without deteriorating the combustion, and the injection engine can be delayed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a specific configuration diagram of a controller.

FIG. 3 is a flowchart for explaining the operation of the present invention.

FIG. 4 is a time chart for explaining the operation of the main injection.

FIG. 5 is a time chart for explaining the relationship between pilot injection and main injection.

FIG. 6 is a configuration diagram of a conventional example.

FIG. 7 is a diagram for explaining the operation of a conventional example.

[Explanation of symbols]

 Reference Signs List 10 diesel engine 12 cylinder head 14 injected fuel reservoir 18 combustion chamber 20 through hole 22 movable nozzle 24 fixed needle 26 injection hole 30 primary fuel chamber 32 secondary fuel chamber 34 piston 36 fuel passage 38 valve closing spring 40 first fuel passage 42 Low pressure tank 44 Second fuel passage 46 Third fuel passage 48 Fourth fuel passage 50 High pressure tank 54 Three-way valve 56 Three-way valve 58 Controller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification symbol FI F02M 61/14 310 F02M 61/14 310L (58) Fields investigated (Int.Cl. ⁶ , DB name) F02M 61/04 F02M 61 / 14 310 F02M 47/00 F02D 41/38 F02D 41/40 F02F 1/24

Claims (3)

(57) [Claims] 1. An injection fuel reservoir formed in a cylinder head for storing injected fuel, a through hole formed in the cylinder head for connecting the injection fuel reservoir with a combustion chamber, and a cylindrically formed one end closed. A movable nozzle having the other end opened and inserted into the fuel injection reservoir, a part of which is slidably inserted into the through hole, and an injection hole communicating with the combustion chamber at the closed end side; A fixed needle which is inserted into the injected fuel reservoir and the movable nozzle, one end of which is fixed to the injected fuel reservoir, and a valve seat which opens and closes the injection hole in accordance with the movement of the movable nozzle at the other end; A piston which is slidably mounted and divides the interior of the injected fuel reservoir into a primary fuel chamber and a secondary fuel chamber and the secondary fuel chamber side is connected to a movable nozzle, and is inserted into the secondary fuel chamber of the injected fuel reservoir. Force to close the nozzle hole of the movable nozzle. An elastic member acting on the ston; and a means for supplying high-pressure fuel to the primary fuel chamber and the secondary fuel chamber at a time and a period according to the operating state of the engine. A fuel injection device for an internal combustion engine, wherein a fuel passage communicating with a fuel chamber and an injection hole of a movable nozzle is formed. 2. An injection fuel reservoir formed in the cylinder head for storing the injected fuel, a through hole formed in the cylinder head for connecting the injection fuel reservoir and the combustion chamber, and a cylindrically formed one end closed. A movable nozzle having the other end opened and inserted into the fuel injection reservoir, a part of which is slidably inserted into the through hole, and an injection hole communicating with the combustion chamber at the closed end side; A fixed needle which is inserted into the injected fuel reservoir and the movable nozzle, one end of which is fixed to the injected fuel reservoir, and a valve seat which opens and closes the injection hole in accordance with the movement of the movable nozzle at the other end; A piston which is slidably mounted and divides the interior of the injected fuel reservoir into a primary fuel chamber and a secondary fuel chamber and the secondary fuel chamber side is connected to a movable nozzle, and is inserted into the secondary fuel chamber of the injected fuel reservoir. Force to close the nozzle hole of the movable nozzle. An elastic member acting on the ston, a low-pressure tank for storing fuel, a high-pressure tank for storing fuel from the low-pressure tank as fuel at a pressure corresponding to the engine speed, a primary fuel chamber and a low-pressure tank for the injected fuel reservoir. A first fuel passage connecting the fuel tank, a second fuel passage connecting the secondary fuel chamber of the injected fuel reservoir and the low-pressure tank, a third fuel passage branched from the middle of the first fuel passage and connected to the high-pressure tank, Second
A fourth fuel passage branched from the middle of the fuel passage and connected to the high-pressure tank, a first switching valve provided at a branch point between the first fuel passage and the third fuel passage and switching the passage according to a command; A second switching valve provided at a branch point between the second fuel passage and the fourth fuel passage to switch a passage according to a command, a rotation speed sensor for detecting an engine rotation speed, and a crank for detecting a crank angle of the engine An angle sensor, an accelerator opening sensor, a fuel injection amount calculating means for calculating a fuel injection amount based on a detection output of the rotation speed sensor and a detection output of the accelerator opening sensor, and a detection output of the crank angle sensor during fuel injection. Switching command means for responding to the first switching valve and the second switching valve for switching from the low pressure tank to the high pressure tank for a time corresponding to a value calculated by the fuel injection amount calculating means in response to the piston. Fuel injection device for a secondary fuel chamber of the injection fuel reservoir on the side secondary fuel chamber and an internal combustion engine fuel passage communicating with the injection hole of the movable nozzles are formed. 3. The fuel injection amount calculating means calculates a pilot fuel injection amount and a main fuel injection amount based on a detection output of an engine speed sensor, and the switching command means detects a crank angle sensor during pilot injection. In response to the output, the first switching valve and the second switching valve are instructed to switch from the low pressure tank to the high pressure tank for a time corresponding to the value calculated by the fuel injection amount calculating means. 10. A method according to claim 9, wherein the first switching valve and the second switching valve are instructed to switch from the low pressure tank to the high pressure tank for a time corresponding to a value calculated by the fuel injection amount calculating means in response to the detection output of the angle sensor. 3. The fuel injection device for an internal combustion engine according to 2.