JP3643188B2 - Injection timing control device for electronically controlled diesel engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection timing control device for an electronically controlled diesel engine, and more particularly to an injection timing control device for an electronically controlled diesel engine that performs injection start timing control using a hydraulic timer.
[0002]
[Prior art]
Conventionally, as a fuel injection pump of a diesel engine, a plunger is provided in a high pressure chamber that receives fuel to be pumped so as to be slidable in a predetermined direction, and this plunger is reciprocated by a cam mechanism or the like composed of a roller and a cam plate. A configuration for pumping fuel is known. That is, the fuel is sucked when the plunger strokes in the direction of increasing the volume of the high-pressure chamber, and the sucked fuel is pumped when the plunger strokes in the direction of decreasing the volume.
[0003]
By the way, in a compression ignition type internal combustion engine such as a diesel engine, the synchronous relationship between the ignition timing of the engine, that is, the timing at which the temperature in the combustion chamber reaches the ignition temperature in the compression process and the timing at which fuel is injected into the combustion chamber. Due to this variation, the combustion characteristics of the fuel change. In particular, when a large amount of fuel is injected before ignition, a large amount of fuel is burned at the same time as ignition, and so-called diesel knock is likely to occur.
[0004]
On the other hand, at the time of engine start, the timing at which the temperature in the combustion chamber reaches the ignition temperature in the compression process tends to be delayed compared to the normal state, and under such a phenomenon, the amount of fuel injected before ignition is relatively small. It increases and it becomes the state where misfire and diesel knock are likely to occur.
[0005]
Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-259622, the injection start timing has been optimized and controlled by an injection timing control device. This injection timing control device is configured to control the injection start timing by driving and controlling a hydraulic timer provided in the fuel injection pump.
[0006]
The hydraulic timer has a roller ring in which a roller is disposed and is held rotatably inside the pump housing, and a timer piston that rotates and displaces the roller ring in the circumferential direction by hydraulic pressure supplied from a feed pump. And a timer spring that urges the timer piston in the retarding direction, a timing control valve (TCV) that controls the amount of movement of the timer piston by controlling the amount of oil supplied from the feed pump, and the like. Yes.
[0007]
Then, the injection timing control device duty-controls the opening / closing operation of the TCV according to the operating conditions of the diesel engine, thereby moving the roller ring in the circumferential direction via the timer piston and thereby the roller that presses the cam plate. The fuel injection start timing is controlled by moving the position.
[0008]
As a specific control method, the engine speed and the accelerator opening are taken as operating conditions of the diesel engine, and the target injection start timing is calculated from the engine speed and the accelerator opening. Further, the current actual fuel injection start timing (actual fuel injection start timing) is calculated from the crank signals and the engine speed. The TCV is feedback-controlled so that the actual fuel injection start timing coincides with the target injection start timing.
[0009]
[Problems to be solved by the invention]
By the way, as described above, misfire and diesel knock are likely to occur at the time of starting the engine, so it is desired to control the timer piston to the advance side. However, immediately after the engine is started, the hydraulic pressure generated by the feed pump provided in the fuel injection pump is zero. From this state, the timer piston whose feed pump hydraulic pressure is constantly urged by the timer spring to the retarded angle side is advanced. It takes some time to reach a value that can be moved to.
[0010]
When feedback control is performed from the start, the feedback control amount has a characteristic that the actual fuel injection start timing becomes smaller as the target fuel injection start timing approaches the target injection start timing. It takes time to become. As described above, when feedback control is performed from the start, the time until the target injection start timing is reached becomes longer, and there is a problem that emission is deteriorated due to delay of complete explosion.
[0011]
The present invention has been made in view of the above points, and performs open loop control at a predetermined advance position and feedback control after reaching the predetermined advance angle until the actual fuel injection start timing reaches the target injection start timing. Accordingly, it is an object of the present invention to provide an injection timing control device for an electronically controlled diesel engine that can perform advance angle control at a target injection start timing with high responsiveness.
[0012]
[Means for Solving the Problems]
  In order to solve the above problems, the present invention is characterized by the following measures.
  In invention of Claim 1,
  A timer piston energized in the retarding direction, and a timer for controlling the injection start timing by feedback controlling the timer piston so that the actual fuel injection start timing coincides with the target injection start timing by the feedback control means. In the injection timing control device of an electronically controlled diesel engine,
  Open loop control means for performing open loop control so that the timer piston is advanced to the maximum advance position;
  When starting and when the engine speed is equal to or less than the predetermined speed during cranking, the open loop control means is operated to open loop control the timer piston to the maximum advance position, and then Injection start time exceeded target start timeFrom the point in time, when the difference between the target injection start timing and the actual fuel injection start timing falls within a predetermined value, or when the ratio of the actual fuel injection start timing to the target injection start timing exceeds a predetermined valueControl switching means for switching the timer piston so as to perform feedback control by the feedback control means;
Is provided.
[0014]
Each means described above operates as follows.
Since the timer piston provided in the timer is biased in the retarding direction, for example, at the start of starting, the timer piston is located at the substantially most retarded position. This timer is driven and controlled by selectively performing feedback control by the feedback control means or open loop control by the open loop control means by the operation of the control switching means.
[0015]
  During open loop control, the timer piston is controlled by open loop control means.maximumLead angle positionTo advance toOpen loop controlled. When the feedback control is performed, the timer piston is feedback-controlled by the feedback control means so that the actual fuel injection start timing coincides with the target injection start timing.
[0016]
  Here, the control switching means performs open loop control of the timer piston to the maximum advance position by the open loop control means at the start.When the actual injection start timing exceeds the target start timing, or when the difference between the target injection start timing and the actual fuel injection start timing falls within a predetermined value, or the actual fuel injection start timing with respect to the target injection start timing. From the point when the ratio exceeds the specified valueThe feedback control by the feedback control means is started.
[0017]
  For this reasonAt startupOpen loop control,By setting the timer piston to the maximum advance position,The advance angle can be advanced early, and the timer piston can reach the advance angle position corresponding to the target injection start time in a short time. Thereby, the time to complete explosion can be shortened, startability can be improved, and deterioration of emissions can be suppressed.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a fuel injection pump to which an injection timing control device for an electronically controlled diesel engine according to an embodiment of the present invention is applied. First, the configuration of this fuel injection pump will be described.
[0019]
The fuel injection pump 1 includes a drive pulley 3 that is drivingly connected to a crankshaft of a diesel engine (not shown) via a belt or the like. Then, the fuel injection pump 1 is driven by the rotation of the drive pulley 3, and the fuel is pumped to each fuel injection nozzle 4 provided for each cylinder of the diesel engine to perform fuel injection.
[0020]
In the fuel injection pump 1, the drive pulley 3 is attached to the tip of the drive shaft 5. A fuel feed pump 6 (developed 90 degrees in this figure) 6 is provided in the middle of the drive shaft 5. Further, a disc-shaped pulsar 7 is attached to the base end side of the drive shaft 5.
[0021]
On the outer peripheral surface of the pulsar 7, four incisors are formed at equal angular intervals in the case of a four-cylinder internal combustion engine, for example, as many as the number of cylinders of a diesel engine. Thus, protrusions are formed at equal angular intervals every 3.75 degrees. And the base end part of the drive shaft 5 is connected with the cam plate 8 via the coupling which is not shown in figure.
[0022]
A roller ring 9 is provided between the pulser 7 and the cam plate 8, and a plurality of cam rollers 10 facing the cam face 8 a of the cam plate 8 are attached along the circumference of the roller ring 9. The same number of cam faces 8a as the number of cylinders of the diesel engine are provided. The cam plate 8 is always urged and engaged with the cam roller 10 by a spring 11.
[0023]
A base end of a fuel pressurizing plunger (hereinafter simply referred to as a plunger) 12 constituting the plunger described in the present embodiment is attached to the cam plate 8 so as to be integrally rotatable. The cam plate 8 and the plunger 12 are connected to the drive shaft. It is rotated in conjunction with the rotation of 5.
[0024]
That is, when the rotational force of the drive shaft 5 is transmitted to the cam plate 8 through the coupling, the cam plate 8 is engaged with the cam roller 10 while rotating, and reciprocates in the horizontal direction in the figure by the same number as the number of cylinders. Driven. Further, the plunger 12 is reciprocated in the same direction while rotating with the reciprocation. That is, the plunger 12 is moved forward (lifted) when the cam face 8a of the cam plate 8 rides on the cam roller 10 of the roller ring 9, and conversely, the plunger 12 is moved backward when the cam face 8a rides the cam roller 10 down. The
[0025]
The plunger 12 is fitted into a cylinder 14 formed in the pump housing 13, and a high-pressure chamber 15 is formed between the distal end surface of the plunger 12 and the bottom surface of the cylinder 14. Further, the same number of intake grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine are formed on the outer periphery on the tip end side of the plunger 12. On the other hand, a distribution passage 18 and a suction port 19 are formed in the pump housing 13 corresponding to the suction groove 16 and the distribution port 17.
[0026]
Then, when the drive shaft 5 is rotated and the fuel feed pump 6 is driven, fuel is supplied from the fuel tank (not shown) into the fuel chamber 21 via the fuel supply port 20. Further, during the suction process in which the plunger 12 is moved backward to decompress the high pressure chamber 15, one of the suction grooves 16 communicates with the suction port 19, whereby fuel is introduced from the fuel chamber 21 to the high pressure chamber 15. . On the other hand, during the compression process in which the plunger 12 is moved forward and the high pressure chamber 15 is pressurized, fuel is pumped from the distribution passage 18 to the fuel injection nozzle 4 for each cylinder and injected.
[0027]
  In the pump housing 13, a spill passage 22 for fuel overflow (spill) that connects the high-pressure chamber 15 and the fuel chamber 21 is formed. In the middle of the spill passage 22, an electromagnetic spill valve 23 is provided as an overflow adjustment valve for adjusting the fuel spill from the high pressure chamber 15. This electromagnetic spill valve 23 is a normally open type valve. When the coil 24 is not energized (off), the valve body 25 is opened and the fuel in the high pressure chamber 15 is made to flow into the fuel chamber.21He is spilled. Further, when the coil 24 is energized (turned on), the valve body 25 is closed and the fuel spill from the high pressure chamber 15 to the fuel chamber 21 is stopped.
[0028]
Therefore, by controlling the energization time of the electromagnetic spill valve 23, the valve 23 is controlled to close and open, and fuel spill adjustment from the high pressure chamber 15 to the fuel chamber 21 is performed. Then, by opening the electromagnetic spill valve 23 during the compression process of the plunger 12, the fuel in the high-pressure chamber 15 is depressurized and the fuel injection from the fuel injection nozzle 4 is stopped.
[0029]
That is, even if the plunger 12 moves forward, the fuel pressure in the high pressure chamber 15 does not increase while the electromagnetic spill valve 23 is open, and fuel injection from the fuel injection nozzle 4 is not performed. Further, during the forward movement of the plunger 12, the fuel injection amount from the fuel injection nozzle 4 is controlled by controlling the timing of closing and opening the electromagnetic spill valve 23.
[0030]
A hydraulic timer 26 (developed 90 degrees in FIG. 1) 26 for adjusting the fuel injection timing is provided below the pump housing 13. The timer 26 has a function of changing the timing at which the cam face 8a is engaged with the cam roller 10, that is, the reciprocating drive timing of the cam plate 8 and the plunger 12 by changing the position of the roller ring 9 with respect to the rotational direction of the drive shaft 5. It plays.
[0031]
The timer 26 is driven by hydraulic pressure, and as shown in FIG. 2 in addition to FIG. 1, a timer housing 27, a timer piston 28 fitted in the housing 27, and a low-pressure chamber in the timer housing 27 are also provided. 29, a timer spring 31 and the like for urging and pressing the timer piston 28 in the retarding direction (that is, toward the pressurizing chamber 30 on the other side). The timer piston 28 is connected to the roller ring 9 via the slide pin 32.
[0032]
Fuel pressurized by the fuel feed pump 6 is introduced into the pressurizing chamber 30 of the timer housing 27. The position (advance position) of the timer piston 28 is determined by the balance between the fuel pressure and the urging force of the timer spring 31. Further, by determining the advance angle position of the timer piston 28, the position of the roller ring 9 is determined, and the reciprocating timing of the plunger 12 with respect to the rotation angle of the drive shaft 5 is determined.
[0033]
The timer 26 is provided with a timing control valve 33 for adjusting the fuel pressure of the timer, that is, the control hydraulic pressure. That is, the pressurizing chamber 30 and the low pressure chamber 29 of the timer housing 27 are communicated with each other by a communication passage 34, and a timing control valve 33 is provided in the middle of the communication passage 34.
[0034]
The timing control valve 33 is an electromagnetic valve that is controlled to be opened and closed by a duty control signal output from an electronic control unit 40 (ECU), which will be described later. Adjusted. And the lift timing of the plunger 12 is controlled by the fuel pressure adjustment, whereby the injection timing can be controlled.
[0035]
Specifically, when the timer piston 28 moves in the arrow X1 direction in FIG. 2, the injection start timing is advanced, and when the timer piston 28 moves in the arrow X2 direction, the injection start timing is retarded. Further, when the timing control valve 33 is opened, the fuel pressure in the pressurizing chamber 30 increases, so that the injection start timing is advanced, and when the timing control valve 33 is closed, the injection start timing is retarded. It has become.
[0036]
On the other hand, on the upper part of the roller ring 9, a rotation speed sensor 35 as an engine rotation detection means composed of an electromagnetic pickup coil is attached facing the outer peripheral surface of the pulsar 7. The rotation speed sensor 35 detects the passage of the projection of the pulsar 7 and the like when it passes, and outputs a timing signal corresponding to the engine rotation speed NE, that is, every predetermined crank angle (in this embodiment, every 3.75 ° CA). ) Output an engine rotation pulse as a rotation angle signal. Further, since the rotation speed sensor 35 is integrated with the roller ring 9, it outputs a reference timing signal at a fixed timing to the plunger lift regardless of the control operation of the timer 26.
[0037]
As described above, the electromagnetic spill valve 23 and the timing control valve 33 provided in the fuel injection pump 1 are connected to the ECU 40 that realizes the feedback control, the open loop control means, and the control switching means by executing the processing described later. The driving of the ECU 40 is controlled.
[0038]
In the fuel injection pump 1 of this embodiment, the following various sensors shown in FIG. 3 are connected to the ECU 40 in addition to the rotation speed sensor 35 described above as sensors for detecting the operating state of the diesel engine.
FIG. 3 is a block diagram showing the peripheral configuration of the ECU 40 of the fuel injection pump of this embodiment. An ignition switch 41 (hereinafter referred to as an IG switch) shown in the figure is a switch operated by the driver when the engine is started. When the IG switch 41 is turned on, the starter is started and the diesel engine is started. The accelerator opening sensor 42 is a sensor provided to detect the accelerator opening ACCP corresponding to the load of the diesel engine from the opening / closing position of a throttle valve provided in the intake pipe. The intake pressure sensor 43 detects the intake air pressure in the intake pipe, and the water temperature sensor 44 detects the cooling water temperature THW of the diesel engine.
[0039]
The crank angle sensor 45 is provided to detect a crankshaft rotation reference position of the diesel engine, for example, a rotation position of the crankshaft with respect to a top dead center of a specific cylinder. Furthermore, the vehicle speed sensor 46 is a sensor that detects a rotation speed of a gear of a transmission (not shown), that is, a vehicle speed (vehicle speed) SP, and generates a pulse signal at a cycle corresponding to the vehicle speed.
[0040]
The ECU 40 suitably controls the electromagnetic spill valve 23 and the timing control valve 33 based on the signals output from the sensors 41 to 46 and the rotation speed sensor 35 described above.
Next, the configuration of the ECU 40 will be described with reference to the block diagram of FIG. The ECU 40 includes a central processing unit (CPU) 47, a read-only memory (ROM) 48 that stores predetermined control programs and maps in advance, a random access memory (RAM) 49 that temporarily stores calculation results of the CPU 47, and the like. A backup RAM 50 for storing data, a clock 58 for generating a predetermined clock signal, and the like, and a logical operation circuit in which these units are connected to an input port 51 and an output port 52 by a bus 53 are configured.
[0041]
The input port 51 includes the IG switch 41, the accelerator opening sensor 42, the intake pressure sensor 43, and the water temperature sensor 44 described above via the buffers 54, 55, 56, and 57, the multiplexer 58, and the A / D converter 59. It is connected. Similarly, the rotational speed sensor 35, the crank angle sensor 45, and the vehicle speed sensor 46 described above are connected to the input port 51 via a waveform shaping circuit 60. Then, the CPU 47 reads the detection signals of the sensors 35, 41 to 46, etc. input through the input port 51 as input values.
[0042]
Further, the electromagnetic spill valve 23 and the timing control valve 33 are connected to the output port 52 via the drive circuits 61 and 62. And CPU47 controls suitably the electromagnetic spill valve 23 and the timing control valve 33 based on the input value read from each sensor 35 and 41-46.
[0043]
  Next, the operation of the injection timing control device applied to the fuel injection pump 1 having the above configuration will be described.The
[0044]
FIG. 4 is a flowchart showing a start-up injection timing control process performed by the start-up injection timing control device. The start injection timing control process program is stored in the ROM 48 and is a routine process that is repeatedly performed at predetermined time intervals. When the start-up injection timing control device shown in the figure is started, first, at step 10, it is determined whether or not the starter is started (STA ON) by operating the IG switch 41.
[0045]
If a negative determination is made in step 10, the IG switch 41 is not operated, that is, the diesel engine is stopped, or is in a normal operation state (an operation state other than the start-up state). In such a state, since it is not necessary to perform the start-up injection timing control, the process proceeds to step 24, a start-up flag FSTA described later is reset (FSTA ← O), and this control process is ended.
[0046]
On the other hand, if an affirmative determination is made in step 10, the process proceeds to step 12, and the ECU 40 calculates the current engine speed NE based on the timing signal supplied from the rotation speed sensor 35, and the current engine. It is determined whether or not the rotational speed NE is equal to or lower than the reference engine rotational speed NE1. Here, the reference engine speed NE1 is set to a value (for example, 900 rpm) that is substantially equal to the speed at which the starter rotates the crankshaft of the diesel engine. Is not yet in its first explosion.
[0047]
The start-up injection timing control process executed in the present embodiment is a process executed during a so-called cranking period from when the starter is started until the diesel engine is started. Therefore, if a negative determination is made in step 12, that is, if the current engine speed NE is greater than the speed NE1 at which the starter rotates the crankshaft, it is not necessary to perform the injection timing control at the start. The present control process is terminated without performing the processes after step 14.
[0048]
On the other hand, if an affirmative determination is made in both step 10 and step 12, the engine is in a cranking period (hereinafter referred to as starting time), and processing after step 14 is performed at the time of starting. First, in step 14, it is determined whether or not the start time flag FSTA is in a reset state (FSTA = 0).
[0049]
Assuming that the engine state is the state immediately after the IG switch 41 is turned on and the starter is started, immediately after the starter is started, the start time flag FSTA is reset (FSTA = 0) by the process of step 24 described above. ). Therefore, an affirmative determination is made at step 14, and the process proceeds to step 16.
[0050]
In step 16, the ECU 40 calculates the target injection start timing ATRG from the engine speed NE calculated based on the signal output from the speed sensor 35 and the engine temperature THW calculated based on the signal output from the water temperature sensor 44. At the same time, the actual injection start timing AACT is calculated based on the engine speed NE and the crank angle signal output from the crank angle sensor 45.
[0051]
Here, the target injection start timing ATRG is an injection start timing at which the diesel engine can be optimally operated when the advance angle position of the timer piston 28 of the timer 26 is set to a position corresponding to the target injection start timing ATRG. It is. On the other hand, the actual injection start timing AACT is an injection start timing corresponding to the current advance angle position of the timer piston 28. Both the target injection start timing ATRG and the actual injection start timing AACT are indicated as a crank angle (° CA).
[0052]
When the target injection start timing ATRG and the actual injection start timing AACT are calculated as described above, the ECU 40 subsequently determines whether or not the target injection start timing ATRG is smaller than the actual injection start timing AACT. Here, a case where a negative determination is made in step 16 and a case where a positive determination is made will be described separately.
[0053]
First, the case where a negative determination is made in step 16 will be described. The state in which the negative determination is made in the processing of step 16 is a state where the actual injection start timing AACT is smaller than the target injection start timing ATRG. Therefore, in order to obtain an optimal engine state that can suppress the occurrence of misfire and the deterioration of emissions, it is necessary to perform the advance processing so that the actual injection start timing AACT becomes the target injection start timing ATRG in a short time. Specifically, it is necessary to rapidly advance the advance position of the timer piston 28 of the timer 26 to the advance position (target advance position) corresponding to the target injection start timing ATRG.
[0054]
However, as described above, immediately after start-up, the timer piston 28 is biased by the timer spring 28 to be positioned at the most retarded position, and the hydraulic pressure supplied from the feed pump 6 to the timer 26 is low. . Therefore, immediately after the start, the value between the actual injection start timing AACT and the target injection start timing ATRG is a large value.
[0055]
Under such conditions, when control is performed so that the actual injection start timing AACT coincides with the target injection start timing ATRG by feedback control as in the prior art, the time until the actual injection start timing AACT reaches the target injection start timing ATRG. As mentioned above, the emission becomes worse as the duration becomes longer and the complete explosion is delayed.
[0056]
Therefore, in this embodiment, when a negative determination is made in step 16, the process proceeds to step 20, and the timer piston 28 is configured to perform open loop control (O / L control). Specifically, the ECU 40 outputs a fixed duty ratio FAFIN corresponding to the maximum valve opening degree to the timing control valve 33, and the actual injection start timing AACT is the maximum advance corresponding to the fixed duty ratio FAFIN regardless of the target injection start timing ATRG. It was set as the structure controlled to advance to an angular position (AMAX). With this configuration, the actual injection start timing AACT can reach the target injection start timing ATRG in a short time with good response.
[0057]
Next, a case where an affirmative determination is made in step 16 will be described. The state in which the determination in step 16 is affirmative is that the actual injection start timing AACT has exceeded the target injection start timing ATRG for the first time, that is, the timer piston 28 has moved to the advance position corresponding to the target injection start timing ATRG. It is.
[0058]
As described above, when the actual injection start timing AACT exceeds the target injection start timing ATRG for the first time and the open loop control in step 20 is further continued, the actual injection start timing AACT overshoots the target injection start timing ATRG. As a result, it becomes an over-advance angle and causes misfire and knocking. For this reason, when an affirmative determination is made in step 16, the start time flag FSTA is set in step 18 (FSTA ← 1), and the open loop control performed in step 20 is stopped in the subsequent step 22, and the process proceeds. The angle control is switched to feedback control (F / B control).
[0059]
Note that, by setting the starting flag FSTA in step 18, a negative determination is made in step 14 in the routine processing after the next time. Therefore, after the open loop control is switched to the feedback control by the process of step 16, the feedback control is continued until the start time flag FSTA is reset in the above-described step 24 (the open loop control is performed). Not) Thereby, after the actual injection start timing AACT reaches the target injection start timing ATRG, it is possible to reliably prevent the open loop control from being performed and the excessive advance angle.
[0060]
When the control processing of step 20 and step 22 described above is selectively performed, the current routine processing ends.
Next, the operation when the start-up injection timing control process according to this embodiment is performed will be described with reference to FIG.
[0061]
FIG. 5 shows time on the horizontal axis and the advance position (injection start timing) of the timer piston 28 on the vertical axis. Since the advance angle position of the timer piston 28 corresponds to the actual injection start timing AACT, the advance angle position of the timer piston 28 is shown as the actual injection start timing AACT in the figure.
[0062]
In FIG. 5, the change in the advance position of the actual injection start timing AACT (advance position of the timer piston 28) when the start-up injection timing control process according to this embodiment is performed is shown by a solid line, and the conventional start-up injection A change in the advance position of the actual injection start time AACT (advance position of the timer piston 28) when the timing control process (only feedback control is performed) is shown by a broken line.
[0063]
First, paying attention to the advance position change of the conventional start injection timing control process indicated by the broken line, the conventional start injection timing control process performs feedback control even at the start without performing open loop control. Therefore, the advance angle position change shows a characteristic of gradually increasing toward the target injection start timing ATRG. In particular, when the actual injection start timing AACT becomes close to the target injection start timing ATRG, the update amount by feedback control becomes slow from the aspect of preventing overshoot, and the time until the actual injection start timing AACT reaches the target injection start timing ATRG (Indicated by t2 in the figure) becomes longer.
[0064]
On the other hand, when the start-up injection timing control process according to the present embodiment is performed, open-loop control is performed at start-up, and the actual injection start timing AACT is fixed duty ratio regardless of the target injection start timing ATRG. Since it is controlled to advance to the maximum advance position (AMAX) corresponding to FAFIN, as shown in the figure, the actual injection start timing AACT is shortened (indicated by t1 in the figure) to the target injection start timing ATRG. Can be reached. As a result, the time until the complete explosion at the time of starting can be greatly shortened (t1 <t2) compared to the conventional case, so that the startability can be improved and the deterioration of emission can be suppressed.
[0065]
Further, since the open loop control at step 20 is stopped and the feedback control at step 22 is switched when the actual injection start timing AACT exceeds the target injection start timing ATRG for the first time, the actual injection start timing AACT is set to the target injection start timing. Since the actual injection start timing AACT does not overshoot the target injection start timing ATRG after the first time when the ATRG is exceeded, highly accurate injection start timing control can be performed.
[0066]
  In the above-described embodiment, the process in step 20 corresponds to an open loop control means, the process in step 22 corresponds to a feedback control means, and the process in step 16 corresponds to a control switching means. It is.
  In the above-described embodiment, the configuration in which the open loop control is switched to the feedback control when the actual injection start timing AACT exceeds the target injection start timing ATRG for the first time in the processing of step 16 has been shown. Is not limited to this. For example, when the difference between the target injection start timing ATRG and the actual injection start timing AACT is equal to or less than a predetermined value (α) (ATRG−AACT ≦ α), Alternatively, when the ratio of the actual injection start timing AACT and the target injection start timing ATRG becomes equal to or greater than a predetermined value (β) (AACT / ATRG ≧ β), The open loop control may be switched to the feedback control.
[0068]
【The invention's effect】
As described above, according to the present invention, it is possible to shorten the time until the complete explosion at the time of start-up, improve the startability, and suppress the deterioration of emissions.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a combustion injection device to which a start-up injection timing control device according to an embodiment of the present invention is applied.
FIG. 2 is an enlarged view showing a timer provided in the combustion injection device.
FIG. 3 is a block diagram showing a configuration of an ECU.
FIG. 4 is a flowchart showing start-up injection timing control processing executed by a start-up injection timing control device.
FIG. 5 is a diagram showing a duty ratio for controlling a timing control valve in the present embodiment while comparing with a conventional one.
[Explanation of symbols]
1 Fuel pump
6 Feed pump
7 Pulsa
8 Cam plate
9 Roller Ring
10 Cam roller
12 Plunger
13 Pump housing
21 Fuel chamber
22 Spill passage
23 Electromagnetic spill valve
26 Timer
27 Timer housing
28 Timer Piston
29 Low pressure chamber
30 Pressurization chamber
31 Timer Spring
32 slide pins
33 Timing control valve
35 RPM sensor
40 ECU
41 IG switch
44 Water temperature sensor
45 Crank angle sensor

Claims (1)

A timer piston energized in the retarding direction, and a timer for controlling the injection start timing by feedback controlling the timer piston so that the actual fuel injection start timing coincides with the target injection start timing by the feedback control means. In the injection timing control device of an electronically controlled diesel engine,
Open loop control means for performing open loop control so that the timer piston is advanced to the maximum advance position;
When starting and when the engine speed is equal to or less than the predetermined speed during cranking, the open loop control means is operated to open loop control the timer piston to the maximum advance position, and then When the injection start timing exceeds the target start timing , or when the difference between the target injection start timing and the actual fuel injection start timing is within a predetermined value, or the ratio of the actual fuel injection start timing to the target injection start timing is An injection timing control device for an electronically controlled diesel engine, characterized by comprising control switching means for switching the timer piston so as to perform feedback control by the feedback control means from a time point when a predetermined value or more is reached .

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