JP2874161B2 - Fuel injection rate control device for diesel engine - Google Patents

Description

Description: Object of the Invention [Industrial application field] The present invention relates to a fuel injection rate control device for a diesel engine which is effective at the time of starting.

2. Description of the Related Art Conventionally, a variable volume chamber communicating with a pressurization chamber provided in a fuel injection pump of a diesel engine is provided, and the volume of the variable volume chamber is increased or decreased by a laminated piezoelectric actuator or the like to inject fuel. 2. Description of the Related Art There is known a technique of controlling a fuel injection rate, that is, controlling a fuel injection rate. Such techniques include, for example,
The following have been proposed: That is, (1) a piezo stack is inserted into a pressure chamber communicating with a pressurization chamber of a fuel injection pump of a diesel engine, and the pressure of the pressure chamber is adjusted according to a voltage applied to the piezo stack to operate the diesel engine. "A fuel injection rate control device for a diesel engine" that controls the fuel injection rate by optimal feedback control according to parameters (Japanese Patent Laid-Open No. 59-18 / 1984)
No. 249).

(2) At a predetermined time when the fuel pressure in the pump chamber for pressurizing the fuel of the fuel injection pump exceeds a certain pressure, the volume of the variable volume chamber communicating with the pump chamber is increased by the electrostrictive actuator, and "Diesel engine fuel injection rate control device" that lowers the injection rate and performs pilot injection with high control accuracy (Japanese Patent Application Laid-Open No. 61-25925).

[Problems to be Solved by the Invention] However, the above-described prior art realizes fuel injection rate control that exerts an effect in a normal operation state after the start and warm-up of the diesel engine is completed. No consideration was given to improving performance. In the starting state, since the rotation speed of the diesel engine is low, the pressurizing / pumping capacity of the fuel injection pump also decreases. Generally, in the starting state, as shown by a broken line in FIG. 7, the target injection rate is high, and the time change of the target injection rate increases rapidly at the injection start timing and rapidly decreases at the injection end timing. Is desirable. However, in the prior art, the so-called multi-stage injection in which the injection with a low injection rate is intermittently performed as shown by the solid line in FIG.

As described above, when the multi-stage injection occurs in the starting state, it is easy to cause a state in which the fuel droplets are mixed in the intake air due to imperfect atomization of the fuel spray inside the combustion chamber, a decrease in the penetration force of the fuel spray, and the like. . For this reason, it is impossible to promptly shift to a smooth combustion state with the deterioration of the ignitability, so that the output of the diesel engine is reduced. Therefore, an output exceeding mechanical loss work such as friction torque of the diesel engine cannot be obtained quickly, and it has been extremely difficult to make a quick transition from a starting state to a so-called blow-up state.

Further, as described above, it is difficult for smooth combustion to be performed in the starting state, so that white smoke contained in the exhaust gas increases,
There were also problems such as generation of pungent odor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection rate control device for a diesel engine that has a simple configuration and can realize a suitable fuel injection even in a start state where the rotation speed of the diesel engine is low.

Configuration of the Invention [Means for Solving the Problems] The present invention made to solve the above problems is, as illustrated in FIG. 1, driven by a diesel engine M1 to supply fuel to the diesel engine M1. Fuel injection pump M2 having a pressurizing chamber for increasing pressure and a variable volume chamber communicating with the pressurizing chamber
Volume change means M3 for changing the volume of the variable volume chamber in accordance with an external command; and starting to determine whether or not the diesel engine M1 is in a start state based on an operation state of the diesel engine M1. When the starting state determining unit M4 determines that the engine is in the starting state, the state determining unit M4 issues a command to reduce the volume of the variable volume chamber over the fuel injection period of the fuel injection pump M2. And a control means M5 for outputting to the change means M3.

Here, the variable volume chamber of the fuel injection pump M2 may be provided, for example, in parallel with the pressurizing chamber, or provided, for example, so as to communicate with a pipe connecting the pressurizing chamber and the diesel engine. May be.

The volume changing means M3 changes the volume of the variable volume chamber according to an external command. For example, it can be realized by a piezoelectric actuator that supplies electric charges from a high-voltage power supply to a stacked piezoelectric element via a drive circuit to expand and contract.
Here, the piezoelectric element has a property of causing distortion when a charge is applied (so-called inverse piezoelectric effect).
A ceramic laminate such as T, an element made of a polymer-based piezoelectric material, an element made of quartz, or the like may be used.

The start state determination means M4 determines whether or not the diesel engine M1 is in a start state based on the operation state of the diesel engine M1. For example, it can be configured to determine whether or not the engine is in a starting state based on a starter signal and an engine coolant temperature. Further, for example, the determination can be made based on a starter signal, an engine rotation speed, an elapsed time from the start of the starter operation, or the like.

When the starting state determination unit M4 determines that the engine is in the starting state, the control unit M5 sends a command to reduce the volume of the variable volume chamber to the volume changing unit M3 over the fuel injection period of the fuel injection pump M2. Output. For example, when in the starting state, a command to apply a high voltage to the piezoelectric element from the start of fuel injection to the end thereof can be output.

The starting state determination means M4 and the control means M5 can be realized by, for example, independent and independent logic circuits. Further, for example, a logical operation circuit may be configured together with a known CPU, a ROM, a RAM, and other peripheral circuit elements, and the above-described means may be realized in accordance with a predetermined processing procedure.

[Operation] As shown in FIG. 1, the fuel injection rate control device for a diesel engine according to the present invention determines that the diesel engine M1 is in the starting state based on the operating state of the diesel engine M1 and that the starting state determining means M4 When determined by, over the fuel injection period of the fuel injection pump M2, a command to reduce the volume of the variable volume chamber communicating with the pressurization chamber of the fuel injection pump M2,
The control means M5 operates to output to the volume changing means M3.

That is, in the starting state of the diesel engine M1, the pressurizing capacity of the fuel injection pump M2, which has been reduced due to the decrease in the rotation speed of the diesel engine M1, is determined by the fuel injection pump M2.
Means for changing the volume of the variable volume chamber communicating with the M2 pressurization chamber
Reduced by M3 and corrected for increase, the above diesel engine M1
That is, the pressure of the fuel to be pumped is increased sufficiently.

Therefore, the fuel injection rate control device for a diesel engine according to the present invention works to increase the fuel injection rate in the starting state.

As described above, the technical problems of the present invention are solved by the operation of each component of the present invention.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a system configuration of a fuel injection rate control device for a diesel engine according to an embodiment of the present invention.

As shown in FIG. 1, a fuel injection rate control device 1 for a diesel engine includes a diesel engine 2, a distribution type fuel injection pump 3 for pressurizing and pumping fuel supplied to the diesel engine 2, and a fuel injection pump 3. It comprises a piezoelectric actuator 4 provided in parallel, a drive circuit 5 for driving the piezoelectric actuator 4, a high-voltage power supply 6, and an electronic control unit (hereinafter simply referred to as ECU) 7 for controlling these.

The diesel engine 2 includes a cylinder 11, a piston
A combustion chamber 14 is formed from the cylinder head 12 and the cylinder head 13, and a fuel injection valve 15 is disposed in the combustion chamber 14.

A drive pulley connected to the distribution type fuel injection pump 3 from the diesel engine 2 to a crankshaft of the diesel engine 2 by a transmission mechanism such as a belt.
The driving force is transmitted via 21. A drive shaft 22, which is connected to the drive pulley 21, is connected to a vane pump 23, which is a fuel feed pump, a pulse gear 24 having a plurality of projections engraved on an outer peripheral surface thereof at equal intervals, and a coupling 25. The coupling 25 is connected to one end of a plunger 27 integrally connected to the cam plate 26, and the other end of the plunger 27 is fitted into the cylinder 28. The coupling 25 and the plunger 27 rotate integrally, but the plunger 27 is supported so as to be able to reciprocate in the axial direction indicated by arrows A and B in FIG. The plunger 27 and the cam plate 26 are urged by a spring 29 in a direction indicated by an arrow A in FIG.

A roller ring 30 is disposed between the coupling 25 and the cam plate 26. A cam roller 31 is attached to a surface of the roller ring 30 facing the cam plate 26 along a circumference around the rotation axis of the roller ring 30. A projection 26a is provided on the surface of the cam plate 26 facing the roller ring 30. The rotational force is transmitted to the cam plate 26 via the coupling 25 by the drive shaft 22 and the cam plate 26 pressed against the roller ring 30 is rotated, whereby the plunger 27 is rotated, and arrows A and B in FIG. Reciprocate in the direction shown by, and distribute and feed the fuel.

A block 33 is attached to the head of the housing 32 of the fuel injection pump 3 by fitting a cylinder 28. Inside the block 33, the plunger 27 and the cylinder
A pressurizing chamber 34 is formed by 28. Plunger 27 above
Are formed on the outer peripheral surface corresponding to the number of cylinders, and the housing 32
It has a fuel introduction recess 35 for sucking the fuel inside, and the pressure of the sucked fuel is increased in the pressurizing chamber 34. Further, the plunger 27 is provided on the outer peripheral surface corresponding to the number of cylinders of the diesel engine 2, and is provided with a distribution port 36 for distributing the pressurized fuel and a spill for overflowing surplus fuel of the pressurized fuel. The port 37 is provided. Further, in the vicinity of the spin port 37 of the plunger 27, the plunger 27
A spill ring 38, which controls the fuel injection amount by adjusting the fuel pressurization end timing by slidably fits outside. The block 33 is provided with a fuel supply passage 39a communicating with the distribution port 36, and a delivery valve 40a connected to the fuel supply passage 39a. The delivery valve 40a
Is connected to the fuel injection valve 15 described above via a fuel pipe 41.

The piezoelectric actuator 4 has a casing 51, a piston 52 that fits in a liquid-tight and slidable manner with a hollow portion inside the casing 51, and one end of the piston 52 abuts the piston 52,
The other end is composed of a piezoelectric element 53 fixed to the lower end surface of the hollow portion of the casing 51, and a signal line 54 which is a conduction path of the electric charge generated by the piezoelectric element 53 or the electric charge supplied to the piezoelectric element 53. . The piezoelectric actuator 4 is screwed to the block 33 of the fuel injection pump 3 by a screw portion 51a engraved on a tip outer peripheral portion of the casing 51, and a hollow portion of the casing 51, an upper end surface 52a of the piston 52 and A variable volume chamber 55 is formed from the block 33, and the variable volume chamber 55 is connected to the fuel injection pump 3 by a communication hole 56.
Is connected to the pressurizing chamber. The piezoelectric element 53 has a structure in which a plurality of disk-shaped members made of PZT are laminated, and a signal line 54 is formed.
When the electric charge is supplied from, the piston 52 is extended in the direction shown by the arrow C in the same figure and the piston 52 is slid in the same direction, so that the volume of the variable volume chamber 55 is reduced. When the electric charge is discharged, the piston 52 contracts in the direction indicated by the arrow D in the same figure and slides the piston 52 in the same direction, so that the volume of the variable volume chamber 55 increases. When a compressive force in the direction indicated by arrow D in FIG. 5 acts on the piezoelectric element 53 with an increase in the fuel pressure inside the variable volume chamber 55, an amount of electric charge corresponding to the strain caused by the compressive force is generated. The piezoelectric element 53 discharges to the signal line 54.

Incidentally, in the fuel injection pump 3 having the above configuration, the vane pump 23, the cam plate 26, and the plunger 27 rotate with the rotation of the drive shaft 22, and the cam plate 26
The plunger 27 shifts to the fuel suction stroke in the process in which the protrusion 26a of the roller ring 30 gets down from the cam roller 31 of the roller ring 30, and introduces the fuel inside the housing 32 into the pressurizing chamber 34, the communication hole 56, and the variable capacity chamber 55, On the other hand, in the process in which the projection 26a of the cam plate 26 rides on the cam roller 31 of the roller ring 30, the plunger 27 shifts to the fuel compression stroke,
4. The pressure inside the communication hole 56 and the variable capacity chamber 55 is increased. Therefore, when the volume of the variable capacity chamber 55 increases, the pressure of the fuel that is pressurized and pumped becomes lower than during the normal compression stroke,
On the other hand, when the volume of the variable capacity chamber 55 decreases, the pressure of the fuel that is pressurized and pumped increases during the normal compression stroke.

The driving circuit 5 for driving the piezoelectric actuator 4 includes:
A capacitor 61 connected in parallel to the high-voltage power supply 6, a current-carrying thyristor 62 and a current-carrying coil 63 connected in series between the capacitor 61 and the piezoelectric actuator 4, and a discharge thyristor connected in parallel to the piezoelectric actuator 4;
64 and the discharge coil 65, when the rectangular signal which is the drive circuit control signal transmitted from the ECU 7 described above rises (ON)
A trigger generator 66 outputs a trigger pulse to the energizing thyristor 62, and outputs a trigger pulse to the discharging thyristor 64 when the rectangular signal falls (OFF).
It is composed of

The drive circuit 5 having the above configuration temporarily stores the high voltage generated by the high-voltage power supply 6 in the capacitor 61, and turns on the energizing thyristor 62 when the rectangular signal from the ECU 7 rises (ON).
, The electric charge stored in the capacitor 61 is supplied to the piezoelectric actuator 4. On the other hand, when the discharging thyristor 64 becomes conductive (ON) when the rectangular signal from the ECU 7 falls, the electric charge stored in the piezoelectric actuator 4 is turned on. To discharge.

The fuel injection rate control device 1 for the diesel engine serves as a detector, and the drive pulley 21 of the fuel injection pump 3 serves as a detector.
The reference signal generation sensor 71 for detecting the fuel injection stroke of each cylinder of the diesel engine 2 when the projection 21a approaches
A rotation speed sensor 72 for detecting the rotation speed Ne of the diesel engine 2 from the rotation speed of the diesel engine 2, a water temperature sensor 73 for detecting the cooling water temperature of the diesel engine 2, and a block temperature sensor for detecting the wall surface temperature of the cylinder block of the diesel engine 2. 74 and a starter switch 75 for outputting a starter signal when the diesel engine 2 is started.

The above-described ECU 7 is configured as a logical operation circuit centering on the CPU 7a, the ROM 7b, the RAM 7c, and the timer 7d, and is connected to the input / output unit 7f via the common bus 7e to perform input / output with the outside. The detection signals of the above sensors and switches and the piezoelectric element voltage of the piezoelectric element 53 are input to the CPU 7a via the input / output unit 7f,
On the other hand, the CPU 7a outputs a control signal to the drive circuit 5 and the high-voltage power supply 6 via the input / output unit 7f. The drive circuit 5 and the ECU 7 are supplied with electric power from an on-vehicle battery 76 via an ignition switch 77.

Next, the fuel injection control process executed by the ECU 7 will be described based on the flowchart shown in FIG. 3, and the injection rate control process will be described based on the flowchart shown in FIG. First, the fuel injection control process will be described with reference to the flowchart of FIG. The fuel injection control process is executed in response to the input of the starter signal. First, in step 100, an initialization process is performed. In the following step 110, a process of reading the detection signals of the sensors described above is performed. Next, proceeding to step 120, it is determined whether the cooling water temperature THW read in step 110 is equal to or higher than a predetermined reference cooling water temperature THW0, and if an affirmative determination is made, the diesel engine 2 is no longer started. The fuel injection control process is terminated once assuming that the vehicle is not in the state, and the fuel injection control process during normal operation is performed. On the other hand, if a negative determination is made, the process proceeds to step 200 assuming that the vehicle is still in the starting state. In step 200, which is executed when it is determined that the engine is in the starting state, after performing an injection rate control process described later, the process returns to step 110 again. Thereafter, the fuel injection control process executes the above steps 100 to 200 every time the starter signal is input.

Next, the injection rate control process executed in step 200 of the fuel injection control process will be described with reference to the flowchart of FIG. The present injection rate control process is executed when a negative determination is made in step 120 of the fuel injection control process.
First, in step 210, processing for reading the piezoelectric element voltage V is performed. In the following step 220, the above step 210
It is determined whether or not the piezoelectric element voltage V read in is equal to or higher than a predetermined control start voltage V0. If a negative determination is made, the pressure inside the pressurizing chamber 34 of the fuel injection pump 3 still in the compression stroke is determined. That is, the process returns to step 210 again assuming that the pressure P in the fuel injection pipe is not sufficiently increased.
If an affirmative determination is made, the process proceeds to step 230 on the assumption that the fuel injection pipe pressure P has increased to near the fuel injection valve opening pressure P0. In step 230, which is executed when it is determined that the fuel injection pipe internal pressure P is sufficiently increased, a process of resetting and starting the timer 7d and starting time measurement is performed. In the following step 240, the drive circuit control signal for supplying (ON) the electric charge to the piezoelectric actuator 4 is transmitted to the drive circuit 5
Is output. By the process of step 240, the high voltage V1 is applied to the piezoelectric actuator 4, the piezoelectric element 53 expands, and the volume of the variable volume chamber 55 decreases, so that the pressure P in the fuel injection pipe increases. Then step 25
Then, it is determined whether or not the timer clock value τ has exceeded a predetermined reference time τ0 based on the fuel injection time. Returning to 240, on the other hand, if a positive determination is made, it is determined that the fuel injection period has already ended, and the routine proceeds to Step 260. In step 260 executed at the end of the fuel injection period, a process of outputting a drive circuit control signal for discharging (OFF) the electric charge from the piezoelectric actuator 4 to the drive circuit 5 is performed. By the process of step 260, the electric charge of the piezoelectric actuator 4 is discharged and the piezoelectric element
Since 53 contracts to increase the volume of the variable volume chamber 55, the pressure P in the fuel injection pipe returns to the normal pressure. After the execution of the step 260, the present injection rate control process is temporarily ended, and the control shifts to the fuel injection control process described above. Thereafter, the present injection rate control processing is performed in step 200 in the fuel injection control processing.
Is executed, the above steps 210 to 260 are executed.

Next, an example of the injection rate control will be described with reference to the timing chart of FIG. When the fuel injection pump 3 shifts to the compression stroke, the fuel pressure in the pressurizing chamber 34, the communication hole 56 and the variable volume chamber 55, that is, the pressure P in the fuel injection pipe starts to increase, and the pressure P in the fuel injection pipe causes Since the piezoelectric element 53 inside 4 receives a compressive force,
When the piezoelectric element voltage V rises and reaches time T1, it becomes equal to or higher than the control start voltage V0. At this time, since the high voltage V1 is applied to the piezoelectric actuator 4, the piezoelectric element 53 expands, and the volume of the variable volume chamber 55 decreases. Therefore, the fuel injection pipe pressure P
Rises and exceeds the fuel injection valve opening pressure P0, so that injection of sufficiently pressurized fuel is started, and the injection rate rapidly increases. At the time T2 after the elapse of the reference time τ0 from the time T1, the fuel injection ends, and the electric charge applied to the piezoelectric actuator 4 is discharged, so that the piezoelectric element 53 contracts and the variable volume chamber 55 Volume increases. Therefore, the pressure P in the fuel injection pipe decreases and falls below the valve opening pressure P0 of the fuel injection valve, so that the fuel injection is terminated and the injection rate decreases rapidly.
Thereafter, while the diesel engine 2 is in the starting state, the above-described control is continuously performed.

In this embodiment, the diesel engine 2 is connected to the diesel engine M1, and the fuel injection pump 3 is connected to the fuel injection pump M2.
The piezoelectric actuator 4, the drive circuit 5, and the high-voltage power supply 6
Correspond to the volume changing means M3. Further, the water temperature sensor 73, the starter switch 75, the ECU 7 and the processing executed by the ECU 7 (steps 110 and 120) are used as the starting state determination means M4 as the ECU 7 and the processing executed by the ECU 7 (steps 210 to 2).
60) function as control means M5.

As described above, according to the present embodiment, when the rotation speed Ne of the diesel engine 2 in the starting state is low and the pressurizing capacity of the fuel injection pump 3 is relatively low, the operation of the piezoelectric actuator 4 Since the pressure P in the fuel injection pipe is corrected to be increased, continuous and appropriate control of the fuel injection rate can be realized from the start time to the end time of the fuel injection.

As described above, since the atomization of the fuel spray in the combustion chamber 14 is promoted with the improvement of the injection rate of the fuel injected into the diesel engine 2 in the starting state, the combustion state is a so-called first explosion state. Rapidly progress in the order of consecutive explosion, complete explosion, and blow-up, so the starting time can be significantly reduced.
Startability is improved.

In addition, since the combustion in the starting state proceeds quickly as described above, it is possible to prevent cooling of moisture and hydrocarbons (HC) in the exhaust gas due to an increase in the engine temperature of the diesel engine 2, so that white smoke and irritating odor are generated. Emission can be suppressed.

Furthermore, since the improvement of the startability removes the restriction at the time of design for improving the combustion performance of the diesel engine 2 in the start state and increases the degree of freedom in design, the compression ratio of the diesel engine 2 is set to a lower value than before. As a result, both the fuel consumption efficiency and the engine output can be improved by reducing the friction loss, and the performance of the diesel engine 2 in a high-speed operation state is significantly increased.

In addition, as an auxiliary measure for starting the diesel engine 2,
For example, a simple configuration that does not require the installation of a dedicated start-up auxiliary device or the execution of control processing, such as the arrangement of a heater for intake air heating, the control of increasing the fuel injection at start-up, the control of advancement of fuel injection timing at start-up, etc. Therefore, the reliability and durability of the fuel injection rate control device 1 for a diesel engine can be improved, and the mountability and versatility of the device when mounted on a vehicle can be expanded.

Further, during the compression stroke of the fuel injection pump 3, it is determined based on the piezoelectric element voltage V output from the piezoelectric actuator 4 that the pressure P in the fuel injection pipe has increased to near the fuel injection valve opening pressure P0. 4, the detection of the injection start timing can be performed accurately and promptly without disposing a detector such as a dedicated sensor.
Control accuracy and responsiveness of the injection rate control are improved.

Further, since the expansion of the piezoelectric actuator 4 is performed for a predetermined time τ0, the pressure P in the fuel injection pipe can be maintained at a high pressure during the injection period.

In this embodiment, the determination of the starting state is made based on the cooling water temperature TH.
W based on, for example, diesel engine 2
If the rotation speed Ne is less than the reference rotation speed Ne0, it may be determined that the engine is in the starting state.

Further, for example, it may be configured to determine that the engine is in the starting state until a predetermined time elapses after the starter signal is input.

Further, in place of the injection rate control process shown in FIG.
The injection rate control process shown in the flowchart of FIG. That is, as shown in the figure, first, the piezoelectric element voltage V is read (step 310), and it is determined whether the piezoelectric element voltage V is equal to or higher than a predetermined control start voltage V0 (step 320). If the determination is affirmative, the drive circuit control signal for supplying (ON) the electric charge to the piezoelectric actuator 4 is transmitted to the drive circuit 5 assuming that the pressure P in the fuel injection pipe has increased to near the fuel injection valve opening pressure P0. Output (step 330), read the piezoelectric element voltage V again (step 340), determine whether the piezoelectric element voltage V is lower than a predetermined control end voltage VE (step 350), and make a positive determination. Then, a drive circuit control signal for discharging (OFF) the electric charge from the piezoelectric actuator 4 is output to the drive circuit 5 (step 360).
This injection rate control processing ends.

In the above-described embodiment, the fuel injection pump 3 including the spill ring 38 has been described. For example, an overflow valve, which is an electromagnetic valve, is interposed between the pressurizing chamber and the low-pressure chamber inside the pump housing. The same effects as those of the above-described embodiment can be obtained by applying the present invention to a fuel injection pump configured to perform start / end control of fuel injection by opening and closing the solenoid valve.

Although several embodiments of the present invention have been described above,
The present invention is not limited to such embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

Effect of the Invention As described in detail above, the fuel injection rate control device for a diesel engine according to the present invention, in the starting state of the diesel engine,
The pressurizing capacity of the fuel injection pump, which is reduced due to the decrease in the rotation speed of the diesel engine, is increased by reducing the volume of the variable volume chamber communicating with the pressurizing chamber of the fuel injection pump by volume changing means. The fuel pumped to the diesel engine is sufficiently pressurized. As a result, the injection rate of the fuel supplied to the diesel engine in the starting state is increased, and the fuel spray is sufficiently diffused inside the combustion chamber, so that it is possible to realize smooth combustion and quick blow-up characteristics, and the startability is greatly improved. It has an excellent effect of improving the quality.

Further, since the combustion proceeds smoothly as described above, the generation of white smoke and pungent odor can be sufficiently suppressed.

Furthermore, the improvement of the startability reduces the design restrictions for ensuring the combustion performance of the diesel engine in the starting state, so that the compression ratio of the diesel engine can be set low. The improvement of the consumption efficiency and the improvement of the engine output can be achieved at the same time, and in particular, the performance of the engine in the high-speed operation state can be improved.

Further, as a measure for promoting the start of the diesel engine, the startability can be improved without providing a dedicated start auxiliary means such as, for example, intake air heating, increasing the amount of fuel at the time of starting, and advancing the fuel injection timing at the time of starting. In addition to this, there is an advantage that the reliability and durability of the device are improved, and the mountability and versatility of the device are also expanded.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram conceptually illustrating the contents of the present invention, FIG. 2 is a system configuration diagram of one embodiment of the present invention, and FIG.
FIG. 4 is a flowchart showing the control, FIG. 5 is a timing chart showing the state of the control, FIG. 6 is a flowchart showing the control of another embodiment, and FIG. 6 is a timing chart showing the state of FIG. M1 ... Diesel engine M2 ... Fuel injection pump M3 ... Volume changing means M4 ... Start condition determination means M5 ... Control means 1 ... Diesel engine fuel injection rate control device 2 ... Diesel engine 3 ... Fuel injection Pump 4 Piezoelectric actuator 5 Drive circuit 6 High-voltage power supply 7 Electronic control unit (ECU) 7a CPU 34 Pressurizing chamber 55 Variable volume chamber 72 Rotational speed Sensor 73: Water temperature sensor, 75: Starter switch

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 1/02 301 F02D 41/00-41/40

Claims (1)

(57) [Claims] 1. A fuel injection pump driven by a diesel engine and having a pressurizing chamber for increasing the pressure of fuel supplied to the diesel engine, a variable volume chamber communicating with the pressurizing chamber, and a volume of the variable volume chamber Volume changing means for changing the diesel engine in accordance with an external command; starting state determining means for determining whether or not the diesel engine is in a starting state based on the operating state of the diesel engine; and starting state determining means. When it is determined that the engine is in the starting state, over the fuel injection period of the fuel injection pump,
Control means for outputting a command to reduce the volume of the variable volume chamber to the volume changing means. A fuel injection rate control device for a diesel engine, comprising: