JPS61272450A - Fuel injector for diesel engine - Google Patents

Abstract

PURPOSE:To reduce noise and vibration without deteriorating output and fuel consumption by installing a means which detects the revolution speed and load and judges the operation state and a control means for permitting the pilot injection. CONSTITUTION:A microcomputer part 70a calculates the fuel injection quantity from the operation condition signal input from a revolution speed detector 57, acceleration sensor 60, etc., and judges the propriety of the pilot injection on the basis of the calculated fuel injection quantity. When the pilot injection is permitted, the valve-opening signal output is set ON, and a valve opening signal is outputted into a driving circuit part 73 for opening a solenoid valve 27. Therefore, the pressure in a high-pressure chamber 19 lowers, and injection is temporarily brought into stop, and then the pressure in the high-pressure chamber 19 increases again to carry out injection, and this operation is continued. While, when the pilot injection is not permitted, and valve-opening signal output is set OFF, and the operation for temporarily bringing the injection into stop is not carried out. Therefore, the fuel injection conforming to the optimum pilot fuel injection condition is permitted, and the deterioration of output and fuel consumption is avoided, and noise and vibration can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection device for a diesel engine having a mechanism for adding pilot fuel injection to the fuel injection of the diesel engine.

[Prior Art] As a conventional measure to reduce combustion noise and imaging of diesel engines, a technique is known in which a small amount of fuel is pilot-injected before main injection.

This pilot fuel injection method includes two plungers for pumping fuel, each of which is driven separately, or two fuel injection nozzles, each of which performs pilot injection and main injection. is one in which each mechanism is built into the injection nozzle (for example, Japanese Patent Laid-Open No. 57
-83658).

However, if the above-mentioned pilot injection is always performed, problems such as a decrease in maximum output and deterioration of fuel efficiency occur.

So 1. Techniques to improve the above problems include a technique that performs pilot injection with high precision during idling to reduce noise and imaging, and also stops pilot injection at high speed to ensure a sufficient exit point.

[Problems to be Solved by the Invention] However, in the above technique, since the presence or absence of pilot injection is uniquely determined by the engine rotational speed, there is a problem that precise control cannot be performed.

Therefore, an object of the present invention is to provide a fuel injection device for a diesel engine that can reduce noise and vibration while improving output and fuel efficiency by precisely controlling pilot fuel injection according to engine operating conditions. There is.

[Means for Solving the Problems] As shown in the basic configuration diagram in FIG. In the injection device M1, a rotation speed detection means M2 for detecting the rotation speed of the engine, a load detection means M3 for detecting the load of the engine, and a signal from the rotation speed detection means M2 and a signal from the load detection means M3 are provided. and a pilot injection for adding a pilot injection to the fuel injection to the aircraft when the determining means M4 determines that the predetermined operating state is the predetermined operating state. The gist of the present invention is a fuel injection device for a diesel engine characterized by being provided with a control means M5.

The rotational speed detection means M2 is a means for detecting the engine rotational speed from, for example, a rotational speed sensor or a rotational speed signal within an electric fuel injection device.

The load detection means M3 is, for example, an accelerator opening sensor or a means for detecting the load state of the engine from a fuel injection amount command value in an electric fuel injection device.

The determining means M4 is a means for determining whether or not the engine is in a predetermined operating state, for example, a state in which pilot injection is performed, based on the detection results of the rotational speed detecting means M2 and the load detecting means M3. For example, this can be done using a microcombi.

The pilot injection control means M5 is a means for performing a pilot fuel injection before the main injection performed by the fuel injection device M1 based on the determination means M4. For example, the determination means M
When step 4 determines that pilot injection is to be performed, an operation is performed to send a valve opening signal to the pilot injection valve.

[Operation] According to the present invention having the above configuration, the rotation speed and the load state are detected from the rotation speed detection means M2 and the load detection means M3, and it is determined whether the detection results are within the range for pilot injection. Based on the determination, the pilot injection control means M5 controls the fuel injection device M1 to
Control to perform pilot injection.

Therefore, the fuel injection system for a diesel engine using the present invention can perform pilot injection depending on the operating condition, and can reduce noise and vibration without deteriorating output and fuel efficiency.

[Example] The apparatus according to the present invention will be explained below with reference to the example shown in FIGS. 2 to 19. FIG. 2 is a block diagram showing an embodiment of the present invention, in which the device of the present invention is applied to a Bosch type distribution fuel injection pump. 1 is a 4-cycle diesel engine, 2 is a fuel injection pump, 3 is a system pump drive shaft, and in a 4-cycle engine, a vane type pump is used that is driven at 1/2 the rotation speed of the crankshaft, and a fuel tank 4 is used. The fuel that has passed through the fuel filter 5 is absorbed from the inlet 6 and discharged to the outlet lower.The fuel that has exited the second outlet lower is filled in the fuel reservoir 8 in the pump housing, and the pressure is regulated by the fuel pressure regulator 9.
Excess fuel is returned to the fuel tank 4. face cam 1
0 and the pump plunger 13 are integrated, and are coupled to the pump drive shaft 3 through a coupling 14 to transmit rotational force. Since this face cam 10 is pressed against a roller 16 by a plunger spring 15, the plunger 13 performs reciprocating motion and rotational motion as the pump drive shaft 3 rotates, sucking fuel from the suction port 17 and then distributing it under pressure. Do the following.

Reference numeral 18 denotes a free piston mechanism for performing pilot fuel injection, which faces the high pressure chamber 19 and includes a free piston 23 that is slidable in the axial direction within the cylinder 20, a return spring 24, and a lift adjustment spacer 25 for the free piston.
, and a free piston back pressure chamber 26.

27 is a solenoid valve that controls the pressure in the free piston back pressure chamber 26 "on" and "off"; 28 is a housing that controls the seat portion 29 and the free piston back pressure chamber 26;
A flow path 30 is provided for returning the fuel to the oil reservoir 8 of the pump 2. A plunger 33 is movable in the axial direction toward the cylindrical inner peripheral portion 34 of the housing 28, and is integrated with a moving core 35 made of a magnetic material. A coil 36 is energized and controlled by an electrical control circuit 40. Reference numeral 41 denotes a return spring which moves the plunger 33 to the right when the coil 36 is not energized to open the seat portion 29 and communicate the free piston back pressure chamber 26 with the flow path 30. 42 is a valve end fixed to the housing 28 by screws. Further, the solenoid valve 27 is fixed to the pump housing by screwing with a threaded portion 44 of the housing 28. Note that 45 is an O-ring for sealing.

50 is an electromagnetic actuator, and the position of the moving core 53 is determined by balancing the force in the direction of arrow a generated by the current flowing through the coil 51 with the force in the direction of arrow A generated by the spring 52.

This moving core 53 is directly connected to a rod 54 and a link mechanism 55.
The spill ring 56 is moved to adjust the fuel injection amount. Further, 57 is a rotation speed detector that detects the rotation speed of the engine, which detects the rotation speed of a gear 58 directly connected to the pump drive shaft 3 using an electromagnetic pickup 59, and converts this electrical signal into an electrical signal as an engine rotation speed signal. It is input to the control circuit 40. An accelerator sensor 60 is an accelerator operation amount detector using, for example, a potentiometer, and inputs an electric signal corresponding to the accelerator operation amount to the electrical control circuit 40. 6
Reference numeral 1 denotes a pump cam angle reference position detector. This is a pump cam angle reference position detector, which has protrusions made of magnetic material located around the plunger 13 of the distribution injection pump at positions corresponding to the reference positions of each cylinder, and detects an electromagnetic pickup or the like fixed to a rough roller ring. A magnetic material detector is provided to generate a signal at a predetermined position of the pump cam angle. The signal of the reference position sensor is input to the electrical control circuit 40. 62 is a key switch that detects the battery voltage and whether the starter is "on" or "off". 63 is an intake temperature sensor that detects the temperature of intake air into the engine. 64 is a cooling water temperature sensor that detects the temperature of engine cooling water.

The electrical control circuit 40 detects the detected value P of the accelerator sensor 60.
A, detection value TI of intake air temperature sensor 63, cooling water temperature sensor 6
4, an A/D converter 65 that converts the detected value TW from analog to digital, a ROM 66 that stores programs and map data, etc., and a RAM 67 that temporarily stores data from various sensors and the contents of arithmetic processing. A waveform shaping section 68 that shapes the engine rotational speed detection wave N of the electromagnetic pickup 59 and converts it into a rectangular wave, and a waveform shaping section 69 that shapes the detection wave S from the pump cam angle reference position detector 61. CP that performs calculation processing based on data from each part above
A microcomputer section 70a consisting of an LJ70 and the following is part of the configuration.

Further, as other configurations of the electrical control circuit 40, the CPU 7
an actuator servo unit 72 that compares the command value VSN from 0 with the actual position signal from the actual position detector 71 and increases or decreases the output to the electromagnetic actuator 50 based on these errors so as to reduce the error; , and a drive circuit section 73 that outputs a current for controlling opening and closing of the electromagnetic valve 27 based on a valve opening command signal from the CPU 70.

With the above configuration, the electrical control circuit 40 includes an engine rotation speed detector 57, an accelerator sensor 60, a pump cam angle reference position detector 61, a key switch 62, an intake air temperature sensor 63,
Upon receiving detection signals from the cooling water temperature sensors 64, the energization conditions for the solenoid valve 27 are determined, and the results are outputted via the drive circuit 65 to control the opening and closing of the solenoid valve 27.

On the other hand, the electric control circuit 40 calculates the target position of the spill ring 56 corresponding to the target injection amount of the fuel injection pump, and compares the signal representing this target position with the actual position signal from the actual position detector 71, A signal is given to the electromagnetic actuator 50 based on these errors, and the electromagnetic actuator 50 is driven to correct the errors.

3 to 19 are flowcharts and graphs showing the processing procedure in the electrical control circuit 40, and the following description will be made according to the flowcharts and graphs. Step 150 in FIG. 3 is a program initialization step. In this step, various preparations necessary for processing are made. The contents are to set the input/output port conditions and to set the contents of the variable storage area to O. Step 151 is a step for determining whether the starter signal is turned on, and when the vehicle's key switch 62 is turned to the starter "on" position, the process proceeds to step 152. Step 1
52 indicates accelerator operation IP^, intake temperature TI, and cooling water temperature TII from load detection means M3 and rotation speed detection means M2.
#, the signal of the engine rotation speed N is sent to the microcomputer section 0
This is the step of importing it into a. Step 153 is the fourth
FIG. 12 is a calculation flowchart and graph of fuel injection flQf shown in detail in FIGS. Q in this step
After calculating r, the process moves to step 154. Step 154
Based on the Qf obtained in step 153, it is determined from the flowcharts and graphs shown in detail in FIGS. 13 and 14 whether or not pilot injection is possible (if yes, a flag of PF=1 is set; if no, a flag of PF=O is set). ) is determined and the process moves to step 155. In step 155, pilot injection is possible (if it is determined that PF=1>, step 15
If the determination is negative (PF-0), the process moves to step 157. In step 156, a valve opening signal is output to the drive circuit section 73 which opens the electromagnetic valve 27 according to the flowcharts shown in detail in FIGS. 15 to 17. Step 157 turns the valve opening signal output "off" and steps 15
Move to 8.

Step 158 is a step for determining whether the driver has turned off the key switch 62. Whether the key switch 62 is "on" or "off" is determined based on whether the battery voltage is higher or lower than a certain voltage value. There is. This method can be used because the battery voltage input to the microcomputer section 70a is passed through the key switch. When it is determined in this step 158 that the key switch is in the "off" position, the process returns to step 151, and step 151 is executed until the driver turns the key switch 62 to the starter "on" position again, and the standby state is reached. becomes. When it is determined that the key switch 62 is not in the "off" position, the process returns to step 152, inputs a new load signal, and moves on to the next calculation. The above is the microcomputer section 70
This is the execution content of the main flowchart executed by a.

Next, the routine for calculating the fuel injection amount Of performed at step 153 in FIG. 3 will be described. FIG. 4 shows a main flowchart for calculating the fuel injection amount Qf, and step 160 is a step for calculating the maximum limit injection fi Q maX.A detailed flowchart is shown in FIG. It is shown in Figure 6.

Step 166 in FIG. 5 is the engine speed N and ROM
66, the engine speed is compared with the engine rotation speed Nn set as a dependent number of the numerical value n, and if the condition of N x Nn is satisfied, the process moves to step 168, and if not, the process moves to step 167.
Move to. Step 167 is a step for performing an operation of adding 1 to the numerical value n. Step 168 calculates Q m from N, Nn and Qn (fuel injection amount corresponding to Nn).
In the step of calculating aX, the calculation of the equation is performed and the process ends once.

The method of defining the pattern shown in FIG. 6 is to store No., Qo, N.
1, Ql, -, Nn, Qn may be stored in an array. The value of n is not fixed but variable,
Therefore, any pattern of the maximum limited injection amount Qmax can be realized. By increasing the value of n, finer control becomes possible, and control can be performed so that the maximum output is achieved within the limited range of smoke density.

In this step 160, the maximum limit injection amount QmaX is calculated from the pattern shown in FIG. 6 using only the engine speed N among the signals indicating the operating conditions. - For example, if N is the rotation speed between N3 and N4, then Q ll1ax
is calculated as

Step 161 is a step of calculating the fuel injection amount at partial load using the engine speed N and the accelerator operation amount PA. A detailed flowchart of step 161 is shown in FIG. 7, and an injection amount pattern during partial load of fuel injection amount is shown in FIG.

When the accelerator operation IPA is between 0% and pAc%, the slope of the pattern is constant, and the pattern line moves between the point N=Nb and the point N=NC according to the amount of accelerator operation. . When the accelerator operation amount P^ is more than pAc%, the pattern line is determined by N=Nc line (
This point is defined on the dotted line in FIG.

The number of these points is arbitrary, as is the number of break points in the case of the maximum restriction injection amount pattern. When the engine speed N is higher than NC, the slope of the line of the pattern also differs according to the amount of accelerator operation, and the smaller the amount of accelerator operation, the larger the slope becomes. Furthermore, the rate of increase in the slope relative to the rate of decrease in the amount of accelerator operation does not need to be linear, and an approximately arbitrary relationship can be obtained by increasing the number of points defined on the N=Nc axis.

This point on the N=NC axis is defined as a point having three types of elements: accelerator operation IPAI, fuel injection amount Q1, and line slope G1, and information on these points is stored in the ROM66 in the microcomputer section 0a. PAI, Ql, G
1, PA2. G2, G2,-, PAn.

Qn, (3n) are stored in this order.

Next, how the partial load injection aqpar is calculated when the accelerator operation amount of the engine is 1)Ax and the engine speed is NX will be explained using FIG. First step 171
Accordingly, it is determined whether the accelerator operation 1i1) Ax is larger or smaller than PAC. If pAX<PAC, the calculation in step 172 is performed to find the intersection point Nk on the N axis. The calculation formula is then used in step 173 to calculate the engine speed N.
Determine the partial load injection amount Qpar from X. The calculation formula is Qpar=(Nk-Nx)XGp. However, Gp is the slope of the line when NX<NC. If the accelerator operation amount FAX is larger than PAc, an intercept value Qk on the N=NC axis is calculated in step 174. For example, assuming that pAx is a value between PA3 and PA4. The intercept value Qk on the N=Nc axis is calculated by the following equation.

Qk= Next, in step 175, the magnitude relationship between Nx and NC is determined. When Nx≦Nc, step 176 sets Qpar = (NC-NX)X(3p
It is calculated as 10Qk. On the other hand, when NX>NC, the slope Gk of the line is calculated in step 177 as follows. Next, in step 178, the partial load injection amount Qpar is calculated as follows: Qpar = Qk - (Nx - N
c) Calculated as xGk. The above calculation is performed to calculate the partial load injection amount Ql)ar.

In FIG. 4, step 162 includes the highest limit injection ffi
This is the step of calculating Qmin. FIG. 9 is a detailed flowchart of step 162, and FIG. 10 is a pattern diagram of the minimum restricted injection amount Qmin. Step 180 in FIG. 9 compares the engine speed NX with a predetermined minimum engine speed NM, and if Nx > NH, step 1
The process moves to step 82, and if not, the process moves to step 181.

Step 181 sets Qmin = QM, step 18
2 sets Qmin=Q and ends once.

Fig. 10 shows a pattern diagram of a state in which the flowchart in Fig. 9 is executed, and when the engine speed Nx is greater than NH, Qllin = O, and when NX is smaller than NH, Qmin = QH. shows.

Step 163 includes the three types of injection flQm explained above.
This is a step of calculating the final target injection amount (target value of injection amount) Qf from aX, Qpar, and Qmin. That is, first, the larger one of the minimum restriction injection IQmin and the partial load injection amount Qpar is selected. Next, this value is compared with the maximum limited injection amount Qmax, the smaller one is selected, and this is set as the target injection amount Qf.

Expressed as a formula, it becomes as follows.

Qf= Min[Qmax, (Max(Qmin,, Q
par ) ) ] step 164 is 160,161
, 162° and 163. This is a step of calculating the target position of the spill ring 56 from the target injection IQf, which is the calculation result calculated through each step of steps 162 and 163. Even if the position of the spill ring 56 is the same, the injection period of the distribution type fuel injection pump changes as the rotational speed of the injection pump changes. The situation is shown in FIG. In this step, the target position of the spill ring 56 is calculated so that the characteristics of the injection pump are corrected and the injection amount is the same as the target injection fjlQf regardless of the rotation speed of the injection pump. The value of the target position signal MSN indicating the target position with respect to the engine speed N and the target injection amount Qf is stored as a map in the ROM 66 in the microcomputer section 0a, and the procedure for calculating the target position signal MSN from the values of this map is as follows. will be explained using an example. The engine speed is N=NX,
The target injection amount calculated in step 163 is Qf = Qf
x, and these values are each Na < Nx × Nb
, Qa < Qfx < Qb. Now (Na
, Qa ) point MSN=VSN1
, the target position signal at the point (Nb, Qa) is expressed as VSN=
VSN2, the target position signal at point (Na, Qb) is VsN=VSN3, and the target position signal at point (Nb, Qb'') is MSN=VSN4. Under these conditions, at point (NX, Qfx) The target position signal of V S
The procedure for determining NX will be explained using FIG. 12. First, the target position signal VSNa at the point (NX, Qa) is determined using the following equation.

ysna= Next, the target position signal VSNb at the point (Nx, Qb) is determined by the following equation.

VSNb= Finally, the target position signal at the point (Nx, Qfx) is
Find N using the following formula.

VSN= Step 1-64 is a step in which calculations shown by a series of calculation formulas as described above are performed.

Step 165 is the same as steps 160 to 16 above.
The calculation result MSN calculated in step 4 is sent to the D/A converter (
This is the step of outputting to a digital-to-analog converter). The D/A converter generates an analog target position signal VS proportional to the target position signal MSN, and the process ends once.

Next, the routine for determining whether or not pilot injection is possible will be explained, which is carried out in step 154 in FIG. FIG. 13 shows a detailed flowchart for determining whether or not the pilot injection is possible, and step 200 is a step for determining the boundary injection IQs corresponding to the engine speed N. The boundary injection amount QS
is obtained by interpolating the values of the map points indicated by black circles in FIG. NId in the graph indicates the idle rotation speed for reference.

Step 201 compares QS obtained in step 200 and Qf obtained in step 153 of FIG. 3, and if Qf≦QS, the process moves to step 203, sets the pilot injection permission flag PF to PF=1, and ends the process once. Also, Qf≦Q
If it is not s, the process moves to step 202, sets PF=O, and ends the process once.

Therefore, the routine shown in FIG. 13 determines whether Qf is within the range of Qs, and if it is within the range, a flag of PF=1 is set, and if it is outside the range, a flag of PF=O is set.

The PF value is used as a branch condition in step 155 of FIG.

Next, the routine for outputting the valve opening signal performed in step 156 in FIG. 3 will be explained. Details of this routine are shown in FIGS. 15 to 17. FIG. 15 shows the main routine for outputting the valve opening signal. Step 210 of the main routine is the sixteenth step.
This is a timer start routine that starts a timer that serves as a reference for fuel injection timing and time shown in detail in the figure.

Step 211 is a valve opening operation routine that outputs a valve opening signal to the drive circuit section 73 that controls opening of the electromagnetic valve 27, which is shown in detail in FIG.

The timer start routine shown in FIG. 16 showing the details of step 210 will be explained. Step 220 determines whether or not timer T has started, and if it has already started, ends once. If the pump cam angle reference position detector 61 has not started, the process moves to step 221 and the pump cam angle reference position detector 61
Input signal S from . Step 222 is step 2
At step 21, it is determined whether or not there is an input of S. If not, the process ends once, and if there is an input of S, the process moves to step 223.

Step 223 starts timer T and ends once.

The valve opening operation routine shown in FIG. 17 showing the details of step 211 compares the timer T with a predetermined set time To in step 230, and if the condition of T≧TO is not satisfied, the valve opening operation routine is terminated. If so, the process moves to step 231. In step 231, the valve opening signal output to the drive circuit section 73 is turned on, and the process proceeds to step 232. Step 2
32 compares the predetermined set time Tc and T≧TC.
If the conditions are not satisfied, the process ends, and if the conditions are satisfied, the process moves to step 233. Step 233 is step 23
The valve opening signal output that was turned on in step 1 is turned off and the process moves to step 234. Step 234 is a timer T
Set to O to stop and exit.

According to the valve opening signal output routine shown in FIGS. 15 to 17, the timer T starts when the pump angle reference position signal @S is input. After the start, when time TO has elapsed, the valve opening signal output is turned on. When the time T TC has elapsed after the "on", the valve opening signal output is turned "off". The above operations are repeated every time this routine is called. Furthermore, if this routine is no longer called while the valve opening signal output is "on", the valve opening signal output is turned "off" in step 157 of the main flowchart in FIG. 3, and pilot injection is no longer performed. It disappears.

Next, the operation will be explained based on the timing charts of FIGS. 18 and 19. FIG. 18 is a timing chart showing a state in which pilot injection is being performed.

In the figure, (A> is the waveform of the pump cam angle reference position signal S, (
B) is the lift amount of the plunger 13, (C) is the current waveform flowing through the coil 41 of the electromagnetic valve 27, and (D> is the nozzle lift amount generated by fuel injection. At the time "to", the pump cam angle reference position signal is This is the time of input. Time t1
is the point at which the nozzle lift starts due to the start of the plunger lift. Time t2 is t.

This shows a state in which the current is turned on by 1 at the elapsed time To. When the current is turned "on" at t2, fuel injection stops and nozzle lift soon disappears. Time t3 is t
This is the point in time when fuel injection is restarted after fuel injection is stopped at step 2. Time t4 indicates a state in which the main fuel injection is stopped. Time t5 is the time when the plunger lift ends. A time point t6 indicates a state in which the current is "off" at the time when the penetration time Tc of to has elapsed. Thereafter, these operations from to to 16 are repeated. Next, the fuel injection suspension operation period from t2 to t13 will be explained. When the electromagnetic valve 27 is energized at 12, the moving core 35 is moved to the right by the return spring 41. As a result, the fuel flow path 30 and the free piston back pressure chamber 26 communicate with each other, and the free piston 23 receives the pressure of the high pressure chamber 19 and is moved to the right by the return spring 24. Therefore, the pressure inside the high pressure chamber 19 decreases and fuel injection from the injection nozzle is also temporarily stopped. Then, at t3, free piston 2
3 hits the lift adjustment spacer 25, the free piston 2
3 stops and the pressure in the high pressure chamber 19 rises again, so fuel is injected from the injection nozzle again. When the required amount is injected, the spill ring 56 of the spill boat is opened and the injection ends at t4. Here, the pilot injection amount can be freely set by changing the time t2 at which the solenoid valve opens, that is, the time To from the reference position signal. Also, during the injection stop period (t3-t2), the lift adjustment spacer 2
It can be adjusted by changing the thickness of the free piston 5 and changing the lift amount of the free piston 23.

Also, the time Tc during which the current to the solenoid valve is turned off is t5 when the plunger lift finishes descending, and after the fuel returns to the free piston back pressure chamber 26 and the free piston 23 returns to its original position, the current rises. Considering the characteristics, the timing should be set so that the current value can be stabilized until the next cycle.

Figure 19 is a timing chart when it is determined not to perform pilot injection, where (A> is the pump cam angle reference position signal, (B) is the plunger lift, (C) is the solenoid valve current value, and (D) is The nozzle lift is shown. Here, a constant current is continuously applied, so the plunger 33 is always in contact with the seat part 29 and the free piston back pressure chamber 2
6 and the flow path 30 are not communicated with each other. Therefore, the free piston 23 always remains at the leftmost position, and the injection valve injects the necessary fuel at a high injection rate without performing pilot injection, thereby maintaining high output.

Although the pilot injection generating means used here has a structure in which a solenoid valve opens and closes a hydraulic chamber to move a free piston, it may alternatively use, for example, a piezoelectric actuator to move the free piston. Furthermore, although the target injection IQf calculated by the CPLI 70 is used as the load state detection means, it is also possible to use a signal from the accelerator sensor 60 or the like instead. FIG. 20 shows a map when the accelerator opening degree of the accelerator sensor 60 is used. By using the boundary accelerator opening degree shown in the figure, it is possible to specify the region in which pilot fuel injection is to be performed.

By using the present embodiment described above, it is possible to inject the optimal fuel corresponding to the engine speed and load condition, and the operating conditions for pilot fuel injection can be changed to the conditions of the engine speed and load condition. To maximize the vibration and noise reduction effect of pilot fuel injection,
It is possible to roughly prevent deterioration of fuel consumption rate and maximum output.

[Effects of the Invention] The present invention described above detects the operating state of the diesel engine from the rotation speed detection means and the load detection means, and determines whether the operating state is a state in which pilot injection is performed by the determining means. It is possible to determine whether

Furthermore, since pilot injection control means is provided for controlling the fuel injection device to perform pilot injection based on the determination by the determination/means, pilot injection can be performed in accordance with the operating state.

Therefore, it is possible to perform fuel injection that meets the optimum pilot fuel injection conditions obtained from the relationship between the engine speed and the load state.

As a result, the effect of reducing noise and vibration caused by pilot fuel injection can be maximized without deteriorating fuel efficiency or reducing maximum output.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, FIGS. 2 to 19 show an embodiment, FIG. 2 is a configuration diagram of this embodiment, and FIG. Flowchart, FIG. 4 is a flowchart for calculating the fuel injection amount Qf in the same flowchart, and FIG. 5 is a calculation flowchart for the fuel injection amount Qf in the same flowchart.
x (maximum limit injection amount) calculation flowchart, 6th
The figure is a graph showing the conditions, Figure 7 is a flowchart for calculating fuel injection amount Of, Qpar (injection amount at partial load), Figure 8 is a graph showing the conditions, and Figure 9 is a flowchart for calculating fuel injection amount Of. Calculation flowchart Q
Calculation of min (minimum limit injection amount) 707 charts,
Fig. 10 is a graph showing the conditions, Fig. 11 is a graph of the relationship between rotation speed and fuel injection amount, Fig. 12 is a graph explaining the calculation to obtain the target spill position, and Fig. 13 is the main flowchart for pilot injection Pf. A flowchart for determining whether or not the
Fig. 14 is a graph showing the conditions, Fig. 15 is a valve opening signal output flowchart of the main flowchart, Fig. 16 is a timer start flowchart, Fig. 17 is a flowchart of the same valve opening operation, and Fig. 18 is a flowchart of the valve opening signal output of the main flowchart. FIG. 19 is an explanatory timing chart of a state in which pilot injection is not performed, and FIG. 20 is a graph showing the conditions of the embodiment. Ml...Fuel injection device M2...Rotational speed detection means M3...Load detection means M4...Judgment means M5.
... Pilot injection control means 1 ... 4-stroke diesel engine 2 ... Fuel pump 13 ... Pump plunger 18 ... Free piston mechanism 19 ... High pressure chamber 20 ... Cylinder 23 ...
... Free piston 24 ... Return spring 25 ... Lift adjustment spacer 26 ... Free piston back pressure chamber 27 ... Solenoid valve 40 ... Electrical control circuit 57 ... Rotation speed detector 59 ... ...Electromagnetic pickup 60...Accelerator sensor 61...Pump cam angle reference position detector 70a...Microcomputer section 71...Actual position detector

Claims (1)

[Scope of Claims] 1. A fuel injection device that controls the fuel injection amount of a diesel engine according to operating conditions, comprising: rotation speed detection means for detecting the rotation speed of the engine; and load detection means for detecting the load of the engine. and determining means for electrically determining a predetermined operating state based on the signal from the rotational speed detecting means and the signal from the load detecting means, and when the determining means determines that the predetermined operating state is the engine. 1. A fuel injection device for a diesel engine, comprising: a pilot injection control means for adding pilot injection to fuel injection into a diesel engine. 2. The determining means determines a boundary load by map interpolation using the rotational speed signal, executes pilot injection when the load obtained from the load detection means is equal to or less than the boundary load, and stops pilot injection otherwise. The fuel injection device for a diesel engine according to claim 1, characterized in that the determination is made as follows. 3. The fuel injection device for a diesel engine according to claim 1 or 2, wherein the load detection means uses an injection amount command value of a device that electrically controls the fuel injection amount.