JP2006257955A - Fuel injection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein an actual phase difference always becomes the ignition timing delay side more than a target phase difference, particularly in acceleration, causing reduced control accuracy, responsiveness and acceleration performance of an actual engine speed being the final control object, since the actual phase difference does not follow the target phase difference and the actual phase difference does not become a proper phase difference to an engine state by response delay such as the repose delay in the target phase difference and the actual phase difference in the phase difference between the fuel ignition timing and a crankshaft in a conventional fuel injection system. <P>SOLUTION: An ECM 21 determines whether or not to be in a state of accelerating rotation of an engine 20 by reading a change in a throttle indicated value from a main throttle 12 (S10). When determined as an accelerating state by this determination, the ECM 21 is put in a correction control mode for controlling the target phase difference in response to a correction target phase difference curve of correcting a conventional target phase difference curve F1 for acceleration (S12). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a fuel injection system that can change a phase difference between a fuel injection timing of a fuel injection pump and a crankshaft of an engine.

A conventional diesel engine is operated with a certain phase difference between a phase of a camshaft that determines a fuel injection timing and a phase of a crankshaft of the engine, which is a driving source of fuel injection in a fuel injection pump.
By changing this phase difference so as to be on the advance side or retard side according to the state of the engine, the engine can be operated efficiently.
As a device for changing the phase of the camshaft of the fuel injection pump, a hydraulic timer unit is known.
In the hydraulic timer unit, the phase angle of both shafts is changed between a camshaft coupling fixed to the camshaft of the fuel injection pump and a pump drive gear to which the rotation of the crankshaft is transmitted. Timer pistons (which may also be referred to as “shuttle pistons”) are provided.
These are provided with a timer piston so as to be spline-fitted in a straight line on the outer peripheral surface of the camshaft coupling, and further provided with a pump drive gear so as to be helically spline-fitted with the outer peripheral surface of the timer piston.
With this configuration, the phase difference between the camshaft coupling and the pump drive gear can be changed by sliding the timer piston in the spline direction of the camshaft coupling.
The timer piston is slid by hydraulic pressure, and the hydraulic pressure is controlled by an ECM that controls the engine.
Therefore, the fuel injection timing can be made appropriate by the ECM controlling the timer piston to the advance side or the retard side according to the state of the engine.
JP 2004-218636 A

Here, the phase difference between the fuel injection timing of the fuel injection pump calculated by the ECM as a command value and the crankshaft of the engine is referred to as “target phase difference”, while the fuel injection timing of the fuel injection pump and the engine crankshaft are The actual phase difference is referred to as “actual phase difference”.
The temporal change of these target phase difference and actual phase difference will be described with reference to FIG.
FIG. 4 shows a case where the target engine speed increases from M1 to M2 by changing the throttle instruction value at time U1, for example.
FIG. 4A is a graph showing a temporal change in the relationship between the target engine speed and the actual engine speed that is the actual engine speed.
L1 is a target engine speed curve showing a temporal change in the target engine speed. In this target engine speed curve L1, a slight slew rate is recognized immediately after time U1, as shown in FIG.
On the other hand, L2 is an actual engine speed curve showing a temporal change in the actual engine speed.
FIG. 4B is a graph showing temporal changes in the relationship between the target phase difference and the actual phase difference.
F1 is a target phase difference curve showing a temporal change of the target phase difference, and it can be seen that the target phase difference is shifted to the advance side after time U1.
On the other hand, G1 is an actual phase difference curve showing a temporal change of the actual phase difference when the control is performed according to the target phase difference curve F1.
Prior to time U1, both the target phase difference curve F1 and the actual phase difference curve G1 are assumed to be D1.
In this case, as shown in FIG. 4A, after the time U1, the target engine speed curve L1 and the actual engine speed curve L2 are different from each other, and the target engine speed curve L1 is changed to the actual engine speed curve L1. L2 is not following. This is an unavoidable problem because the actual engine speed is directly affected by the load.
On the other hand, as shown in FIG. 4B, the target phase difference curve F1 and the actual phase difference curve G1 also deviate, and the actual phase difference curve G1 does not follow the target phase difference curve F1.
This is caused by a response delay or the like in the hydraulic control of the hydraulic timer unit, and this response delay is an inevitable problem.
In addition, the difference between the actual phase difference and the target phase difference due to such a response delay means that the actual phase difference is not an appropriate phase difference with respect to the engine state. This may cause a decrease in control accuracy, responsiveness, acceleration, etc. of a certain actual engine speed.
In particular, at the time of acceleration, as shown in FIG. 4, there is a problem that the actual phase difference is always retarded from the target phase difference.
Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel injection system capable of setting the actual phase difference to an appropriate phase difference with respect to the engine state. is there.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

  In the first aspect of the present invention, in the fuel injection system capable of changing the phase difference between the fuel injection timing of the fuel injection pump and the crankshaft of the engine, whether or not the engine is in an acceleration state based on the change in the indicated value of the throttle Acceleration determination means for determining the target phase difference, and target phase difference correction means for correcting the target phase difference with a predetermined correction value when the acceleration determination means determines that the engine is in an acceleration state. It is.

  According to a second aspect of the invention, there is provided a corrected target phase difference storage means for storing in advance a corrected target phase difference, which is a result of correcting the target phase difference with the correction value, as a map.

  As effects of the present invention, the following effects can be obtained.

  According to the configuration of the first aspect, the actual phase difference can be matched with the original target phase difference, and the actual phase difference can be appropriately controlled. Therefore, the control accuracy and responsiveness of the engine speed are improved. In addition, control performance such as acceleration can be improved as compared with the conventional one.

  According to the configuration of the second aspect, since it is not necessary to calculate the correction target phase difference from the target phase difference and the correction value every time the engine is accelerated, it is possible to increase the speed of the entire phase control process. Become.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following best mode for carrying out the present invention is an example embodying the present invention, and is not intended to limit the technical scope of the present invention.
FIG. 1 is a block diagram showing a schematic configuration of a fuel injection system, FIG. 2 is a schematic configuration diagram of a fuel injection pump and related devices, and FIG. 3 shows the relationship between crankshaft pulses, camshaft pulses, and fuel injection timing. FIG. 4 is a graph showing an example of a temporal change in the conventional target phase difference and actual phase difference, and FIG. 5 is an example of processing for correcting the actual phase difference so as to be appropriate for the engine state. FIG. 6 is a graph showing an example of a temporal change in the target phase difference and the actual phase difference after the correction processing.

<Outline configuration>
First, the schematic configuration of the fuel injection system 1 of the present invention will be described with reference to FIG.
The fuel injection system 1 described here will be described as a case where the fuel injection system 1 is used as a control system for a fuel injection pump of an engine provided in a ship, for example. However, the same effect can be obtained by using this system. As long as it is adopted, it may be adopted for any kind of thing.
As shown in FIG. 1, the fuel injection system 1 is roughly divided into an operation unit 10 and an engine 20.
The operation unit 10 is provided in the cab of the ship, and is provided with, for example, a display unit 11, a main throttle 12, a sub throttle 13, and the like.
The display unit 11 displays the state of the ship adopting this system, a warning, and the like, and can issue a warning by voice by incorporating a speaker or the like.
The main throttle 12 operates, for example, the throttle valve 29 of the engine 20 and is operated when the ship is in a normal operation state, and is, for example, a lever type.
The sub-throttle 13 operates the throttle valve 29 in the same manner as the main throttle 12, but is different from the main throttle 12 in that it is operated when the ship is not in a normal operation state. The shape of the sub-throttle 13 is, for example, a knob type (volume type) switch.
Each of the display unit 11 and the main throttle 12 has its own control unit, and communicates with an ECM 21 (Engine Control Module), which is a control unit on the engine 20 side, so that the operation unit 10 and the engine 20 as a whole. Control is in progress.
If the communication method such as the protocol is different between the operation unit 10 and the engine 20, a communication repeater 15 is provided for matching the communication method as shown in FIG.
The sub-throttle 13 is directly connected to the ECM 21 on the engine 20 side, and the communication system is the same as that on the engine 20 side.
The engine 20 is, for example, a diesel engine, and is provided with an ECM 21, a crankshaft rotation speed sensor 22, a camshaft rotation speed sensor 23, a retarding electromagnetic valve 24, an advance electromagnetic valve 25, a rack 28, and the like.
The ECM 21 controls an actuator and the like related to the engine 20 based on the state of the operation system such as the sensor related to the engine 20 and the operation unit 10 described above.
The crankshaft rotation speed sensor 22 detects the rotation speed of the crankshaft of the engine 20 and outputs the detection result to the ECM 21 as a crankshaft pulse.
That is, the rotational speed of the engine 20 can be detected using the crankshaft rotational speed sensor 22.
The camshaft rotation speed sensor 23 detects the rotation speed of the camshaft of the engine 20 and outputs the detection result to the ECM 21 as a camshaft pulse.
Further, the crankshaft rotation speed sensor 22 and the camshaft rotation speed sensor 23 can be constituted by optical sensors. For example, a predetermined number of marks are provided on the crankshaft, the camshaft itself or gears at predetermined intervals at the time of manufacture. Thus, the ECM 21 can calculate the rotational speeds of the crankshaft and the camshaft 41 by detecting the mark with the optical sensor.
The delay angle solenoid valve 24 and the advance angle solenoid valve 25 are used to move the timer piston of the hydraulic timer unit for changing the cam shaft phase of the fuel injection pump 40 as shown in FIG. It is a hydraulic control valve for controlling the hydraulic pressure to slide to the side.
The rack 28 adjusts the amount of fuel injected from the fuel injection pump 40.

<Fuel injection pump>
Next, a schematic configuration of the fuel injection pump 40 and related devices will be described with reference to FIG.
The hydraulic timer unit 50 in FIG. 2 is shown in cross section.
In particular, for the sake of convenience, the timer piston 52 is shown in a state where it is vertically divided by a one-dot chain line, the state moved to the retard side position is indicated by the timer piston 52a, while the state moved to the advance side position is shown. This is indicated by the timer piston 52b.
Of course, the actual timer piston 52 is not divided into two parts by a one-dot chain line as described above, but is integrally formed. In FIG. 2, only the movement state of the timer piston 52 is described. It is divided into two by a one-dot chain line.
The fuel injection pump 40 is for pressure-feeding the fuel stored in the fuel tank to an injection nozzle provided in a cylinder of the engine 20, and is driven by a cam shaft 41. A coupling fixing member 42 for fixing the coupling 51 to the cam shaft 41 is fixed.
Further, the fuel injection pump 40 is provided with supply ports 43 for supplying fuel to the cylinders of the engine 20, and the example shown in FIG.
Further, the fuel injection pump 40 is integrally provided with a governor 30 and a hydraulic timer unit 50.
The governor 30 includes the rack 28, and the rack 28 is driven by a proportional solenoid that is driven and controlled by the ECM 21.
The hydraulic timer unit 50 is provided with a timer piston 52 that is straight and spline-fitted to the outer peripheral surface of the camshaft coupling 51, and a pump drive gear 53 that is helically spline-fitted to the outer peripheral surface of the timer piston 52. Is provided.
The pump drive gear 53 is fixed by a receiving gear 55 that receives a rotational force from the crankshaft of the engine 20 and a bolt 56.
Thus, the camshaft 41 can be rotated by the rotation of the crankshaft, and the timer piston 52 is slid in the spline direction of the camshaft coupling 51 (left and right as viewed in FIG. 2). By moving, the phase difference between the camshaft coupling 51 and the pump drive gear 53 can be changed.
Here, as already described above, the helical shape of the spline fitting is configured so that the camshaft is retarded by sliding the timer piston 52 to the 52a side and advanced by sliding the timer piston 52 to the 52b side. ing.
Further, a space formed on the outer peripheral side of the timer piston 52 fitted with the pump drive gear 53 is a retarded angle chamber 57a, and a space formed on the inner peripheral side of the timer piston 52 fitted with the camshaft coupling 51 is an advanced angle chamber 57b. Respectively.
In this case, the timer piston 52 can be slid to the retard side (52a side) by pumping the pressure oil to the retard chamber 57a, while the timer is pumped by pumping the pressure oil to the advance chamber 57b. The piston 52 can be slid to the advance side (52b side).
In addition, the retarding solenoid valve 24 and the advancement solenoid valve 25 described above are arranged in the retarding pressure fluid path 58a that leads to the retarding chamber 57a and the advancement pressure oil path 58b that leads to the advancement chamber 57b, respectively. The retard solenoid valve 24 and the advance solenoid valve 25 are controlled and operated by the ECM 21 to feed the pressure oil and slide the timer piston 52.
With this configuration, the ECM 21 functions as a control unit that hydraulically controls the timer piston 52 in accordance with the state of the engine 20, and freely delays the phase difference between the crankshaft of the engine 20 and the camshaft 41. It is possible to make an angle or advance.

<Actual phase difference>
As already described above, the crankshaft and camshaft 41 are preliminarily marked with the shaft itself or the gear, and this mark is detected by the crankshaft rotational speed sensor 22 and the camshaft rotational speed sensor 23, and the detection is performed. Based on the resulting crankshaft pulse and camshaft pulse, the ECM 21 calculates the rotation speed of the crankshaft and camshaft 41.
Therefore, the ECM 21 can also calculate the phase difference between the crankshaft and the camshaft based on the difference between the detection times of the crankshaft pulse and the camshaft pulse.
Therefore, the relationship among the crankshaft pulse, the camshaft pulse, and the actual fuel injection timing will be described with reference to FIG.
FIG. 3 shows the crankshaft pulses J1, J2, and J3, the actual fuel injection timing (hereinafter referred to as “FIC”) injected from a certain supply port 43, and the camshaft pulse corresponding to the FIC. This shows the relationship with T2.
3A shows the relationship (phase difference) in pulse detection time when the camshaft 41 is advanced with respect to the crankshaft, and FIG. 3B shows the camshaft 41 cranked. The relationship (phase difference) of the detection time of the pulse in the state close | similar to the axis | shaft is shown.
As shown in FIG. 3, for example, the crankshaft pulses J1, J2, and J3 correspond to marks that are recorded in advance on the crankshaft so as to be detected every 30 [deg] as an angle.
Further, the phase of the camshaft pulse T2 is obtained by calculating an angle B that is a phase difference from the crankshaft pulse J2 corresponding to the camshaft pulse T2.
Incidentally, if fuel injection is actually performed at the phase of the camshaft pulse T2, this angle B becomes the phase difference between the fuel injection timing and the crankshaft. However, the example shown in FIG. Due to the design of the injection pump 40 and the like, the camshaft pulse T2 and the FIC do not coincide with each other, and the FIC is deviated by 10 [deg] from the camshaft pulse T2.
That is, the phase of the actual fuel injection timing is performed at a time that is 10 [deg] earlier than the detection timing of the camshaft pulse T2.
Therefore, the ECM 21 finally calculates the phase difference between the FIC and the crankshaft pulse J2 as “actual phase difference C” in consideration of the deviation of 10 [deg].
That is, this actual phase difference C is the phase difference between the fuel injection timing determined by the camshaft 41 and the crankshaft.

<Actual phase difference C calculation>
Next, a method for calculating the actual phase difference C with respect to the crankshaft pulse J2 will be described.
First, the ECM 21 measures the time from when the crankshaft pulse J1 immediately before the crankshaft pulse J2 is detected until the camshaft pulse T2 is detected, and calculates the phase difference corresponding to the measured time as the angle A. To do.
Then, the ECM 21 calculates the difference of the angle A as an angle B from an angle 30 [deg] which is a predetermined phase difference between the crankshaft pulse J1 and the crankshaft pulse J2.
That is, the calculation of (30−A) = B is performed.
Since this angle B is the phase difference of the camshaft pulse T2 with respect to the crankshaft pulse J2, the ECM 21 calculates the phase difference between the camshaft pulse T2 and the FIC (10 [deg] described above) determined in advance at this angle B. The actual phase difference C is calculated by adding.
That is, B + 10 is calculated.
Thus, the actual phase difference C can be calculated by performing the pulse detection and calculation processing.
The ECM 21 can distinguish the crankshaft pulse J2 from other crankshaft pulses J1 as follows.
For example, a mark is written in advance so that the reset pulse JX can be detected close to the crankshaft pulse J2 and at intervals of 30 [deg] or less.
By marking the mark corresponding to the reset pulse JX in this way, when the ECM 21 detects two pulses at intervals shorter than 30 [deg], which is the crankshaft pulse interval, the first pulse is cranked. It can be recognized as the axial pulse J2.
As the ECM 21 changes the actual phase difference C calculated as described above according to the state of the engine 20, it becomes possible to determine the fuel injection timing suitable for the state of the engine 20.

<Difference between target phase difference and actual phase difference>
By the way, as already described with reference to FIG. 4, the target phase difference and the actual phase difference deviate due to the response delay in the hydraulic control of the hydraulic timer unit, and the control accuracy of the actual engine speed, the response, the acceleration This may cause a decrease in sex.
In particular, at the time of acceleration, as shown in FIG. 4, there is a problem that the actual phase difference is always retarded from the target phase difference.
An example of processing for correcting the actual phase difference so as to be appropriate for the state of the engine will be described with reference to FIG.

<Correction>
The ECM 21 reads a change in the throttle instruction value from the main throttle 12 to determine whether or not the rotation of the engine 20 is being accelerated (S10).
That is, the ECM 21 is an example of an acceleration determination unit that determines whether or not the engine 20 is in an acceleration state based on a change in the throttle instruction value.
If it is determined in step S10 that the vehicle is accelerating, the process proceeds to step S12. If it is determined that the vehicle is not accelerating, the process proceeds to step S30.
When the process proceeds to step S12, the ECM 21 enters a correction control mode for controlling the target phase difference according to the corrected target phase difference curve obtained by correcting the conventional target phase difference curve F1 for acceleration (S12).
Here, the above correction will be described with reference to FIG.
FIG. 6 (a) shows the target engine speed curve L1 and the actual engine speed curve L2 shown in FIG. 4 (a). The target engine speed is changed by changing the throttle instruction value at time U5. Shows a case where M rises from M1 to M2.
In FIG. 6B, F2 is a corrected target phase difference curve obtained by correcting the above-described conventional target phase difference curve F1.
G2 is an actual phase difference curve showing a temporal change of the actual phase difference C when the control is performed according to the corrected target phase difference curve F2.
It is assumed that the time at which the process of step S12 is performed is time U5, and both the target phase difference and the actual phase difference before time U5 are D1 as in the case before time U1 in FIG.
The corrected target phase difference curve F2 is obtained by correcting the conventional target phase difference curve F1 to the advance side by a predetermined correction value. This correction value is, for example, (D2- D1).
That is, the ECM 21 that performs such processing also functions as target phase difference correction means that corrects the target phase difference with a predetermined correction value when it is determined that the engine 20 is in an acceleration state. is there.
Therefore, even when the actual phase difference is retarded from the target phase difference during acceleration, the ECM 21 performs control according to the corrected target phase difference curve F2 in which the target phase difference is corrected to the advanced angle side with the retard amount as a correction value. By doing so, the actual phase difference can be matched with the original target phase difference.
That is, the actual phase difference curve G1, which is the locus of the actual phase difference C, matches the target phase difference curve F1.
By performing such correction processing, the actual phase difference can be matched with the original target phase difference, and the actual phase difference can be appropriately controlled. Control performance such as accuracy, responsiveness, and acceleration can be improved as compared with the conventional one.
When the process shifts to step S30, the ECM 21 shifts to the normal mode in which the normal control is performed without performing the correction process as described above (S30).

<Mapping>
The ECM 21 can also store in advance a corrected target phase difference curve F2 that is a result of correcting the target phase difference curve F1 with the correction value (D2-D1).
That is, the ECM 21 can also have a function of a corrected target phase difference storage unit that stores in advance a corrected target phase difference, which is a result of correcting the target phase difference with the correction value, as a map.
By storing the corrected target phase difference curve F2 in advance as described above, it is not necessary to calculate the corrected target phase difference curve F2 from the target phase difference curve F1 and the correction value every time the engine 20 is accelerated. Therefore, it is possible to increase the processing speed of the entire phase control.

The block diagram which showed schematic structure of the fuel-injection system. The schematic block diagram of a fuel-injection pump and its related apparatus. The figure which showed the relationship between a crankshaft pulse, a camshaft pulse, and fuel injection timing. The graph which showed an example of the time change of the conventional target phase difference and an actual phase difference. The flowchart which showed an example of the process which correct | amends an actual phase difference so that it may become appropriate with respect to the state of an engine. The graph which showed an example of the time change of the target phase difference after an amendment process, and an actual phase difference.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection system 10 Operation part 15 Communication repeater 20 Engine 21 ECM
22 Crankshaft rotation speed sensor 23 Camshaft rotation speed sensor 24 Solenoid valve for retard angle 25 Solenoid valve for advance angle 28 Rack 29 Throttle valve 30 Governor 40 Fuel injection pump

Claims (2)

In the fuel injection system that can change the phase difference between the fuel injection timing of the fuel injection pump and the crankshaft of the engine,
Acceleration determining means for determining whether or not the engine is in an acceleration state based on a change in the indicated value of the throttle;
Target phase difference correction means for correcting the target phase difference with a predetermined correction value when the acceleration determination means determines that the engine is in an acceleration state;
A fuel injection system comprising: 2. The fuel injection system according to claim 1, further comprising a corrected target phase difference storage unit that stores in advance a corrected target phase difference, which is a result of correcting the target phase difference with the correction value, as a map.

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