JP2830512B2 - Idle state detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine such as a diesel engine and, more particularly, to an idle state detecting method for detecting an idle state.

[0002]

2. Description of the Related Art Conventionally, for example, in a diesel engine, a technology for controlling a load at the time of idling in order to realize a stable idling speed, improve fuel efficiency and prevent deterioration of exhaust emission has been proposed. It is disclosed in Japanese Patent Publication No. 110644. In this prior art, after the engine speed exceeds a predetermined speed, the accelerator opening is fully closed, the vehicle speed is "0", and a reference is established for several seconds after these conditions are satisfied. After a lapse of time, it is determined that the engine is in the idling stable state, and the load control at the time of idling is executed.

[0003]

However, when the determination processing as in the above-mentioned prior art is employed to determine the idling stable state, for example, the accelerator opening is fully opened in a no-load state, that is, the racing is performed. Therefore, when the accelerator opening is returned to the fully closed state after the engine reaches the maximum rotation state, the engine speed does not decrease to the stable target idle speed even if the vehicle speed is "0" and a predetermined reference time has elapsed. There was something. In particular, in the case of an engine having a large inertial mass due to the relationship between the flywheel and the like, when the accelerator opening is returned to the fully closed state from the maximum rotation state, the time required for the engine to decrease to the target idle speed becomes longer, and the target idle speed becomes longer. There is a possibility that the idle state may be determined before the rotation speed drops. Therefore, in a system in which the integral control amount used for the fuel injection amount control is learned from the idle speed control (ISC), the learning update to the minus side of the integral control amount becomes large by repeating the racing to some extent. , The integral control amount becomes too small. As a result, the fuel injection amount corrected by the integral control amount becomes too small, and there is a possibility that engine stalling may occur when racing is stopped.

[0004] That is, as shown in FIG. 13, when the accelerator pedal opening ACCP is fully opened and fully closed to some extent by racing, a predetermined engine idle speed NF which is expected to reach a predetermined target engine speed NF from the highest engine speed NE. Reference time α
Does not fall to the target idle speed NF even after passing through, and the idle stable state is determined uniformly after the reference time α. At this time, since the engine speed NE at the time of determining the idling stable state is higher than the target idle speed NF, the learning value of the integral control amount NFI in the ISC is gradually learned and updated to the minus side. Become.
As a result, when the racing is repeated a certain number of times, the integral control amount NFI becomes too small, the fuel injection amount becomes too small, and there is a risk of engine stall.

[0005] Further, in the prior art, the engine speed,
It has been determined that the idle state is stable only after a uniform reference time has elapsed after all the conditions of the accelerator opening and the vehicle speed have been satisfied. Therefore, when the accelerator opening is returned to the fully closed state from a state where the engine speed is slightly higher than the target idle speed, the engine speed immediately returns to the target idle speed, but the reference time does not elapse. Is not considered idle steady state. Therefore, control such as ISC becomes impossible only during that time, and there is a possibility that response delay such as ISC control may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to detect an idling stable state at a target idle speed with high accuracy and to control the fuel injection amount from idle speed control. An object of the present invention is to provide an idle state detection method capable of preventing erroneous learning even when learning an integral control amount or the like used for control.

[0007]

In order to achieve the above object, the present invention provides an idle state detecting method.
At the time when the accelerator opening of the internal combustion engine is fully closed.
The engine rotation at the time when the accelerator opening is fully closed
Depending on the magnitude of the deviation between the speed and the target idle speed.
The set delay time has elapsed and the vehicle is stopped.
When it is detected, it is determined that it is in the idle state.
The summary of the

[0008]

According to the above configuration, the accelerator opening is set to the fully closed position.
Engine speed at a given time and a predetermined target idle speed
By setting the delay time according to the deviation from
Engine speed at the time when the cell opening is fully closed
Regardless of whether the engine speed reaches the target idle speed
It can be determined that it is idle after it actually drops,
Further, the time until the determination is made can be reduced. Ma
In addition, when the delay time has elapsed and the vehicle stopped state is detected.
Is likely to fluctuate by determining that it is idle when
Set the delay time appropriately for
However, immediately determine the vehicle speed that is hard to fluctuate,
Idle state detection can be performed accurately
In addition, the detection frequency can be increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the idle state detecting method according to the present invention is applied to a diesel engine automobile will be described in detail with reference to FIGS. FIG. 10 is a schematic configuration diagram showing a fuel injection amount control device for a supercharged diesel engine in this embodiment, and FIG. 11 is a sectional view showing the distribution type fuel injection pump 1. The fuel injection pump 1 includes a drive pulley 3 which is drivingly connected to a crankshaft 40 of the diesel engine 2 via a belt or the like. The fuel injection pump 1 is driven by the rotation of the drive pulley 3, and the fuel is injected under pressure to each fuel injection nozzle 4 provided for each cylinder (four cylinders in this case) of the diesel engine 2 to perform fuel injection. .

In the fuel injection pump 1, a drive pulley 3 is attached to a tip of a drive shaft 5.
In the middle of the drive shaft 5, there is provided a fuel feed pump (developed at 90 degrees in this figure) 6 composed of a vane type pump. Further, a disk-shaped pulser 7 is attached to the base end side of the drive shaft 5. The outer surface of the pulsar 7 has a diesel engine 2
In this case, four cutting teeth are formed at equal angular intervals, that is, four cutting teeth are formed at equal angular intervals, and between each cutting tooth, 14 (total of 56) projections are formed at equal angular intervals. I have. The base end of the drive shaft 5 is connected to the cam plate 8 via a coupling (not shown).

A roller ring 9 is provided between the pulsar 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. I have. Cam face 8
a is provided as many as the number of cylinders of the diesel engine 2. The cam plate 8 is always urged and engaged with the cam roller 10 by the spring 11.

A base end of a fuel pressurizing plunger 12 is attached to the cam plate 8 so as to be integrally rotatable. The cam plate 8 and the plunger 12 are rotated in conjunction with the rotation of the drive shaft 5. That is, the rotational force of the drive shaft 5 is transmitted to the cam plate 8 via the coupling, so that the cam plate 8 rotates and engages with the cam roller 10 to reciprocate in the left-right direction by the same number as the number of cylinders. Driven. Further, the plunger 12 is driven to reciprocate in the same direction while rotating with the reciprocation. That is,
The plunger 12 is moved forward (lift) while 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 back while the cam face 8a rides down the cam roller 10.

The plunger 12 is fitted into a cylinder 14 formed in a pump housing 13, and a high pressure chamber 15 is formed between a tip surface of the plunger 12 and a bottom surface of the cylinder 14.
It has become. Also, on the outer periphery of the tip side of the plunger 12,
The same number of intake grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine 2 are formed. In addition, these suction grooves 16
And the pump housing 13 corresponding to the distribution port 17.
Is formed with a distribution passage 18 and a suction port 19.

When the drive shaft 5 is rotated and the fuel feed pump 6 is driven, fuel is supplied from a fuel tank (not shown) into the fuel chamber 21 through the fuel supply port 20. Also, during the suction stroke in which the plunger 12 is moved back and the high-pressure chamber 15 is depressurized, the suction groove 1
The fuel is introduced from the fuel chamber 21 to the high-pressure chamber 15 when one of the ports 6 communicates with the suction port 19. On the other hand, during the compression stroke in which the plunger 12 is moved forward and the high-pressure chamber 15 is pressurized, fuel is pressure-fed from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder and injected.

The pump housing 13 is provided with a spill passage 22 for fuel spill that connects the high-pressure chamber 15 and the fuel chamber 21. In the middle of the spill passage 22, there is provided a well-known electromagnetic spill valve 23 for injection adjustment. This electromagnetic spill valve 23 is a normally open type valve,
When the coil 24 is not energized (off), the valve 25 is opened, and the fuel in the high-pressure chamber 15 overflows to the fuel chamber 21.
When the coil 24 is energized (turned on), the valve body 25 is closed, and the overflow of fuel from the high-pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, by controlling the energizing time of the electromagnetic spill valve 23, the valve 23 is controlled to close and open, and the overflow of the fuel from the high-pressure chamber 15 to the fuel chamber 21 is adjusted. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the fuel in the high-pressure chamber 15 is reduced in pressure, and the fuel injection from the fuel injection nozzle 4 is stopped. That is, even when 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 the fuel injection from the fuel injection nozzle 4 is not performed. Further, during the forward movement of the plunger 12, by controlling the timing of closing and opening the electromagnetic spill valve 23, the amount of fuel injected from the fuel injection nozzle 4 is controlled.

Below the pump housing 13, there is provided a timer device (developed at 90 degrees in this figure) 26 for controlling fuel injection timing. This timer device 26
Controls the position of the roller ring 9 with respect to the rotation direction of the drive shaft 5, thereby controlling the timing at which the cam face 8a engages with the cam roller 10, that is, the reciprocating timing of the cam plate 8 and the plunger 12.

The timer device 26 is operated by hydraulic pressure, and includes a timer housing 27, a timer piston 28 fitted in the housing 27, and a timer A timer spring 31 for urging the piston 28 toward the other pressurizing chamber 30 is provided. The timer piston 28 is connected to the roller ring 9 via the slide pin 32.
It is connected to the.

In the pressurizing chamber 30 of the timer housing 27,
The fuel pressurized by the fuel feed pump 6 is introduced. The 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, the position of the roller ring 9 is determined by determining the position of the timer piston 28, and the plunger 1 is moved through the cam plate 8.
2 is determined.

In order to control the fuel pressure of the timer device 26, the timer device 26 is provided with a timing control valve 33. That is, the pressurizing chamber 30 and the low-pressure chamber 29 of the timer housing 27 are communicated by the communication passage 34, and the timing control valve 33 is provided in the communication passage 34. The timing control valve 33 is an electromagnetic valve whose opening and closing are controlled by a duty-controlled energization signal, and the fuel pressure in the pressurizing chamber 30 is adjusted by controlling the opening and closing of the valve 33.
Then, the lift timing of the plunger 12 is controlled by the fuel pressure adjustment, and the fuel injection timing from each fuel injection nozzle 4 is adjusted.

On the upper part of the roller ring 9, a rotation speed sensor 35 composed of an electromagnetic pickup coil is mounted so as to face the outer peripheral surface of the pulser 7. This rotation speed sensor 35
Detects the passage of a projection or the like of the pulsar 7 when they cross, and outputs a timing signal (engine rotation pulse) corresponding to the engine speed NE. Further, since the rotation speed sensor 35 is integrated with the roller ring 9, the rotation speed sensor 35 outputs a reference timing signal to the plunger lift at a constant timing regardless of the control operation of the timer device 26.

Next, the diesel engine 2 will be described. In the diesel engine 2, a main combustion chamber 44 corresponding to each cylinder is formed by the cylinder 41, the piston 42, and the cylinder head 43. or,
Each of the main combustion chambers 44 is connected to a sub-combustion chamber 45 provided correspondingly for each cylinder. Then, the fuel injected from each fuel injection nozzle 4 is supplied to each sub combustion chamber 45. Further, a well-known glow plug 46 as a start-up assist device is attached to each sub-combustion chamber 45.

The diesel engine 2 is provided with an intake pipe 47 and an exhaust pipe 50. The intake pipe 47 is provided with a compressor 49 of a turbocharger 48 constituting a supercharger, and the exhaust pipe 50 is provided with a turbocharger. 48
Turbine 51 is provided. The exhaust pipe 50 is provided with a waste gate valve 52 for adjusting the supercharging pressure PiM. As is well known, the turbocharger 48 uses the energy of the exhaust gas to rotate the turbine 51, and a compressor 49 on the same axis as the turbine 51.
To increase the pressure of the intake air. Thus, a high-density air-fuel mixture is sent into the main combustion chamber 44 to burn a large amount of fuel, thereby increasing the output of the diesel engine 2.

The diesel engine 2 has an exhaust pipe 5
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in the cylinder 0 to the suction port 53 of the intake pipe 47. An exhaust gas recirculation valve (EGR valve) 55 for adjusting the amount of exhaust gas recirculation is provided in the middle of the recirculation pipe 54. The opening and closing of the EGR valve 55 is controlled by the control of a vacuum switching valve (VSV) 56.

Further, a throttle valve 58 is provided in the middle of the intake pipe 47 so as to open and close in accordance with the amount of depression of an accelerator pedal 57. Also, its throttle valve 5
A bypass passage 59 is provided in parallel with 8, and a bypass throttle valve 60 is provided in the bypass passage 59. The opening and closing of the bypass throttle valve 60 is controlled by an actuator 63 having a two-stage diaphragm chamber driven by control of two VSVs 61 and 62. The opening and closing of the bypass throttle valve 60 is controlled in accordance with various operation states. For example, it is controlled to a half-open state during idle operation to reduce noise and vibration, to a fully opened state during normal operation, and to a fully closed state during smooth operation to stop smoothly.

In addition, the diesel engine 2 is provided with a starter 64 for applying a rotational force by cranking at the time of start of the diesel engine 2. The starter 64 has a starter switch 65 for detecting and outputting the on / off operation. Is provided. As is well known, the starter 64 is turned on and off by the operation of an ignition switch (not shown). While the ignition switch is being operated, the starter 64 is turned on and the starter signal ST is output from the starter switch 65. It is supposed to be.

Further, in this embodiment, an air conditioner (not shown) driven in conjunction with the diesel engine 2
C) is provided, and an air conditioner switch 68 that is operated to turn on and off the air conditioner is provided.
The air conditioner switch 68 outputs an air conditioner signal AC according to the on / off operation. Then, as described above, the electromagnetic spill valve 23, the timing control valve 33 provided in the fuel injection pump 1 and the diesel engine 2,
The glow plug 46 and each of the VSVs 56, 61, 62 are electrically connected to an electronic control unit (hereinafter simply referred to as "ECU") 71, and their drive timing is controlled by the ECU 71.

As sensors for detecting the operating state, in addition to the rotation speed sensor 35, the following various sensors are provided. That is, the intake pipe 47 is provided with an intake air temperature sensor 72 for detecting an intake air temperature THA near the air cleaner 66. Further, an accelerator opening sensor 73 for detecting the accelerator opening ACCP corresponding to the load of the diesel engine 2 from the open / close position of the throttle valve 58 is provided. A fully-closed position switch (not shown) for detecting the fully-closed position of the throttle valve 58 is integrated into the accelerator opening sensor 73. Therefore, when the throttle valve 58 is fully closed in the idle range of the diesel engine 2, the fully closed signal LL from the fully closed position switch is turned on, and when the throttle valve 58 is opened to some extent in the output range, The fully closed signal LL from the fully closed position switch is turned off, and the accelerator opening ACCP is detected.

An intake pressure sensor 74 for detecting the intake air pressure after supercharging by the turbocharger 48, that is, the supercharging pressure PiM, is provided near the intake port 53. Further, a water temperature sensor 75 for detecting the cooling water temperature THW of the diesel engine 2 is provided. Further, a crank angle sensor 76 for detecting a rotation reference position of the crankshaft 40 of the diesel engine 2, for example, a rotation position of the crankshaft 40 with respect to a top dead center of a specific cylinder is provided. Furthermore, the transmission 67 of the diesel engine 2
Has a magnet 77 rotated by the rotation of the gear.
A vehicle speed sensor 77 is provided for detecting the vehicle speed (vehicle speed) SP by turning on / off the reed switch 77b according to a.

The ECU 71 is connected to each of the sensors 72 to 77 described above,
5. The starter switch 65 and the air conditioner switch 68 are respectively connected. Also, the ECU 71 controls each sensor 3
5, 72 to 77, the electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, and the VSVs 56, 61, 62 are suitably controlled based on signals output from the starter switch 65 and the air conditioner switch 68.

Next, the configuration of the ECU 71 will be described with reference to the block diagram of FIG. ECU 71
Is a central processing unit (CPU) 81, a read-only memory (RO) in which a predetermined control program,
M) 82, a random access memory (RAM) 83 for temporarily storing the operation results and the like of the CPU 81, a backup RAM 84 for storing previously stored data, and the like, and a bus 87 for connecting these components to the input port 85 and the output port 86.
Are configured as logical operation circuits connected with each other.

The input port 85 has an intake air temperature sensor 72, an accelerator opening sensor 73, an intake pressure sensor 74,
Water temperature sensor 75, starter switch 65 and air conditioner switch 68 are connected to buffers 88, 89, 90, 91, 9 respectively.
2, 93, a multiplexer 94 and an A / D converter 95. Similarly, the input port 85
The above-described rotation speed sensor 35, crank angle sensor 76, and vehicle speed sensor 77 are connected via a waveform shaping circuit 96. Then, the CPU 81 reads, as input values, detection signals of the sensors 35, 72 to 77, the starter switch 65, the air conditioner switch 68, and the like, which are input through the input port 85. Each drive circuit 9 is connected to the output port 86.
The electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, the VSVs 56, 61, 62 and the like are connected via 7, 98, 99, 100, 101, 102.

Then, the CPU 81 controls each of the sensors 35 and 72.
~ 77, starter switch 65 and air conditioner switch 6
8, based on the input value read from the electromagnetic spill valve 23,
Timing control valve 33, glow plug 46
And the VSVs 56, 61, 62 and the like are suitably controlled. Next, processing operations of idle state detection and fuel injection amount control performed by the above-described ECU 71 will be described with reference to FIGS.
It will be described according to.

The flowchart shown in FIG. 1 is a processing routine for detecting an idling state of the diesel engine 2 for detecting an idling stable state of the diesel 2 among the processing executed by the ECU 71, in which an ignition switch (not shown) is started. , And thereafter is executed by a periodic interruption every predetermined time (8 msec).

When the process proceeds to this routine, first, at step 101, the starter switch 65, the accelerator opening sensor 73, the water temperature sensor 75, and the vehicle speed sensor 77
Starter signal ST, accelerator opening ACCP, fully closed signal LL, cooling water temperature THW, and vehicle speed SP based on the detected values of
Read the value of Next, in step 102, the corrected accelerator opening ACCPA is calculated based on the accelerator opening ACCP and the cooling water temperature THW. The corrected accelerator opening ACCPA is obtained by comparing the starting pseudo accelerator opening ACSTA obtained in accordance with the cooling water temperature THW with the accelerator opening ACCP and the like.

Subsequently, in step 103, it is determined whether or not the starter 64 is off, that is, whether or not cranking by driving the starter 64 has been completed, based on the starter signal ST previously read. Here, if the starter 64 is not off, step 114
Move to. On the other hand, if the starter 64 is off and cranking is completed, the process proceeds to step 104.

At step 104, it is determined whether or not the previously read fully closed signal LL is off, that is, whether or not the accelerator is fully closed. Here, when the fully closed signal LL is off and the accelerator opening ACCP is not fully closed, it is determined that the vehicle is not in the idle state, and the process directly proceeds to step 114. On the other hand, when the fully closed signal LL is on and the accelerator opening A
If the CCP is fully closed, the process proceeds to the next step 105.

In step 105, it is determined whether or not the fully closed signal LL in the previous processing cycle has been turned off. That is, it is determined whether or not the accelerator opening ACCP has been switched from the open state including the fully open state to the fully closed state. Here, when the accelerator opening ACCP is switched from the open state to the fully closed state, steps 106, 107,
Each processing of 108 is executed.

That is, in step 106, the engine speed NE is read based on the value detected by the speed sensor 35, and the target idle speed NF at that time is read. The target idle speed NF is a value calculated in a main routine described later. Next, in step 107, the reference time TIDL until the diesel engine 2 reaches the idling stable state is calculated and set based on the engine speed NE and the target idle speed NF according to the following equation (1).

TIDL = (NE−NF) * 1.1 / 1000 (1) That is, in steps 106 and 107, the accelerator opening A
Engine speed NE when CCP is returned to fully closed state
Is obtained, and a reference time TIDL corresponding to a deviation between the engine speed NE and the target idle speed NF is obtained. Subsequently, in step 108, 8 msec after the accelerator opening ACCP is switched to the fully closed state.
The count time C8 by the counter is reset. That is, counting by the 8 msec counter is started, and the subsequent processing is temporarily ended.

On the other hand, in step 105, the fully closed signal LL in the previous processing cycle is on, and the accelerator opening A
If the CCP continues the fully closed state, step 1
Move to 09 . Then, in step 109 ,
It is determined whether or not the count time C8 is smaller than the reference time TIDL. That is, it is determined whether or not the reference time TIDL has elapsed since the accelerator opening ACCP returned to the fully closed state.

Here, the count time C8 is equal to the reference time TI.
If it is less than DL, it is determined that the diesel engine 2 is not in the idling stable state yet, and in step 110, the count time C8 is incremented, and the subsequent processing is temporarily terminated. Step 10
In step 9, if the count time C8 has reached the reference time TIDL, it is determined that the diesel engine 2 partially satisfies the condition of the idling stable state, and the next step is performed to determine whether or not the idling stable state. 111,1
12 is executed.

That is, in step 111, the corrected accelerator opening ACCP previously obtained in step 102
It is determined whether or not A is “0%”. In other words, it is determined whether or not the corrected accelerator opening ACCPA obtained by correcting the accelerator opening ACCP during idling is fully closed. Here, the corrected accelerator opening ACC
If PA is not “0%”, the process proceeds to step 114.

On the other hand, if the corrected accelerator opening ACCPA is "0%" in step 111, it is determined in step 112 whether or not the vehicle speed SP is "0 km / h", that is, the vehicle is surely stopped. It is determined whether or not there is. Here, when the vehicle speed SP is “0 km / h”, it is determined that the vehicle is in the idling stable state that satisfies all the conditions including the determinations in steps 109 and 111, and in step 113, it is indicated that the vehicle is in the idling stable state. The idle flag FIDL is set to "1", and the subsequent processing is temporarily ended. If the vehicle speed SP is not "0 km / h", the process proceeds from step 112 to step 114.

Then, Step 103, Step 10
4. After shifting from step 111 or step 112, in step 114, the idle flag FIDL is reset to "0" assuming that all the conditions for the idling stable state are not satisfied, and the subsequent processing is temporarily ended. I do. Detection of the idle stable state is performed as described above, and whether or not the idle stable state is set is determined by the idle flag FIDL.

Subsequently, the flowchart shown in FIG.
Among the processes executed by U71, this is a main routine related to a process of controlling the fuel injection amount from the fuel injection pump 1 during the operation of the diesel engine 2, and is executed by a periodic interruption every predetermined time. When the process proceeds to this routine, first, in step 201, the rotation speed sensor 35, the accelerator opening sensor 73, the intake pressure sensor 7
4. From the detected values of the water temperature sensor 75 and the air conditioner switch 68, the engine speed NE, the accelerator opening ACCP,
Supercharging pressure PiM, cooling water temperature THW and air conditioner signal AC
Respectively.

Next, at step 202, a water temperature correction coefficient F (t) is calculated from the read cooling water temperature THW. The water temperature correction coefficient F (t) is obtained by referring to a predetermined map as shown in FIG. Subsequently, at step 203, the water temperature correction coefficient F
The target idle speed NF is calculated from (t) and the air conditioner signal AC or the like. That is, the water temperature correction coefficient F is set to a predetermined reference rotational speed according to the on / off state of the air conditioner signal AC.
The target idle speed NF is obtained by multiplying (t).

Further, in step 204, an expected control amount NFP is calculated from the water temperature correction coefficient F (t) and the air conditioner signal AC or the like. That is, the expected control amount NFP is obtained by substituting the reference predetermined rotation speed and the water temperature correction coefficient F (t) into different calculation formulas determined in advance according to the ON / OFF of the air conditioner signal AC. Then, in step 205, it is determined whether or not the idle flag FIDL is "1", that is, whether or not the idle stable state is established. This idle flag FIDL is set in the idle state detection routine of FIG. 1 as described above.

Here, the idle flag FIDL is "0".
Is in the non-idle state, that is, when the diesel engine 2 is in the normal output range,
Move to 09. On the other hand, if the idle flag FIDL is in the idle stable state of “1”, the step 2
Shift to 06. In step 206, the FCCB
Executes control processing. That is, in the idling stable state, a process is executed to correct the variation in the injection amount of each cylinder of the diesel engine 2 to eliminate uneven rotation of the diesel engine 2 and smoothly approach the target idle speed NF. . The specific processing content is not described here.

In step 207, idle speed control (ISC) is performed based on the previously read engine speed NE and the previously obtained target idle speed NF.
Is calculated. That is, the integral control amount NFI is a value obtained in the idling stable state, and the target idle speed NF and the actual engine speed N
It is obtained from the difference from E and is a value for performing feedback control so that the actual engine speed NE matches the target idle speed NF. The specific processing content is not described here.

Subsequently, at step 208, an integral control amount learning value NFIGQ for injection amount correction is calculated based on the engine speed NE, the coolant temperature THW, the integral control amount NFI obtained at step 207, and the like. That is, the integral control amount learning value NFIGQ is a value obtained in the idling stable state, and includes the engine speed NE and the cooling water temperature TH.
When W or the like satisfies a required condition, the value is learned and updated in a predetermined cycle by comparing the magnitude of the integral control amount learning value NFIGQ and the integral control amount NFI. The specific processing content is not described here.

Then, step 205 or step 20
8, in step 209, the corrected engine speed NEISC for ISC is calculated and set according to the following equation (2) based on the engine speed NE, the estimated control amount NFP, and the integral control amount NFI. NEISC = NE− (NFP + NFI) (2) That is, the engine speed NE in the idling stable state is obtained by the correction amount obtained in steps 204 and 207.
Of the engine speed NEISC after the correction to make the engine speed close to the target idle speed NF.

In step 210, the basic fuel injection amount QBASE is calculated based on the corrected engine speed NEISC and the accelerator opening ACCP read in advance. The calculation of the basic injection amount QBASE is performed with reference to a predetermined map (not shown) using the corrected engine speed NEISC and the accelerator opening ACCP as parameters. Also, this basic injection amount Q
In the calculation of BASE, low-temperature start increase correction, acceleration increase correction, sudden deceleration increase correction, and the like are performed as necessary based on respective values such as the cooling water temperature THW, the accelerator opening ACCP, and the engine speed NE.

Subsequently, at step 211, the rotational speed correction value KF is calculated based on the previously read engine rotational speed NE.
Calculate T. This rotation speed correction value KFT is obtained by referring to a predetermined map as shown in FIG. or,
In step 212, the correction coefficient KNF is calculated based on the integral control amount learning value NFIGQ previously obtained. This correction coefficient KNF is obtained by referring to a predetermined map as shown in FIG.

In step 213, the rotational speed correction value KFT and the integral control amount learning value NF previously determined
Based on the IGQ, the correction coefficient KNF, and the like, an injection amount temperature correction coefficient KF for calculating a maximum injection amount QFULL to be described later is calculated and set according to the following equation (3). KF = KFT * NFIGQ * KNF + 1 (3) Then, in step 214, the basic maximum injection amount QSPF0 is obtained from the previously read engine speed NE. The basic maximum injection amount QSPF0 is obtained by referring to a predetermined map as shown in FIG.

In step 215, the maximum injection amount QSPF1 is similarly obtained from the engine speed NE. This maximum injection increase QSPF1 is obtained by referring to a predetermined map as shown in FIG. Further, in step 216, the fixed injection amount QFIX is similarly calculated based on the engine speed NE in accordance with a predetermined arithmetic expression.
Is calculated.

Subsequently, at step 217, an intake pressure correction coefficient K2 is obtained from the supercharging pressure PiM read earlier. This intake pressure correction coefficient K2 is obtained by referring to a predetermined map as shown in FIG. Then, in step 218, the basic maximum injection amount QSPF0, the maximum injection increase amount QSPF1, and the fixed injection amount QF determined earlier
IX, injection amount temperature characteristic correction coefficient KF, and intake pressure correction coefficient K2
The maximum injection quantity QFULL corresponding to the smoke limit
Is calculated. This calculation is performed according to the following equation (4). QFULL = (K2 * QSPF1 + QSPF0) * KF + QFIX (4) Then, in step 219, the basic injection amount QBASE obtained in step 210 is compared with the maximum injection amount QFULL obtained in step 218, and the smaller one is compared. Is set as the final injection amount QFIN.

Subsequently, at step 220, an injection amount command value VSSP corresponding to the final injection amount QFIN is obtained. Then, in step 221, the obtained injection amount command value VSSP is output, that is, the basic injection amount Q
The drive of the electromagnetic spill valve 23 is controlled based on the injection amount command value VSSP corresponding to BASE or the maximum injection amount QFULL, and the subsequent processing is temporarily terminated.

As described above, the processing for controlling the fuel injection amount of the diesel engine 2 in the idling stable state or the non-idling state is executed. As described above, in this embodiment, as described in the idle state detection routine of FIG. 1, the predetermined reference time TI after the accelerator opening ACCP of the diesel engine 2 is returned to the fully closed state.
After the lapse of DL, when the corrected accelerator opening ACCPA is “0%” and the vehicle speed SP satisfies the condition of “0 km / h”, it is determined that the diesel engine 2 is in the idling stable state. I have. Moreover, the engine speed N at the time when the accelerator opening ACCP is returned to the fully closed state
E is obtained, and a reference time TIDL is determined from the difference between the engine speed NE and the target idle speed NF at that time according to the magnitude of the difference.

Therefore, the reference time TIDL can be estimated as a time until the engine speed NE reaches the target idle speed NF when the accelerator opening ACCP is fully closed. That is, the reference time TIDL is determined to be relatively long when the engine speed NE is high when the accelerator opening ACCP is fully closed. On the other hand, the reference time TIDL is equal to the accelerator opening ACCP.
When the engine speed NE is low when the engine is fully closed,
A relatively short time is determined accordingly.

Therefore, by counting the reference time TIDL from the time point when the accelerator opening ACCP is returned to the fully closed state, the engine speed NE becomes the target idle speed N
When settled at F, it is possible to determine that the diesel engine 2 is in the idling stable state, and it is possible to reliably detect the idling stable state. That is, it is possible to accurately detect the idling stable state at the target idle speed NF.

In the diesel engine 2, even when the accelerator opening ACCP is properly opened or fully opened (racing) in a no-load state, when the actual engine speed NE drops to the target idle speed NF. Since it can be determined that the engine is in the idling stable state, it is not determined that the diesel engine 2 is in the idling stable state before the engine speed drops to the target idle speed NF.

Therefore, like the fuel injection amount control in this embodiment, in the system in which the integrated control amount NFI used for the fuel injection amount control is learned and updated from the ISC,
Even if racing is repeated to some extent, since the diesel engine 2 is determined to be in the idling stable state when it reaches the target idle speed NF, the integral control amount NFI is not learned and updated to the negative side, and the integral control amount The NFI does not become too small. As a result, the final injection amount QFIN corrected by the integral control amount NFI
Will not become too small and will not cause engine stalls even if you stop racing.

FIG. 9 shows the accelerator opening ACCP, the engine speed NE, and the idle flag FI in the fuel injection amount control performed by employing the idle state detecting method of this embodiment.
6 is a time chart for explaining the relationship between DL and ISC integral control amount NFI. In this figure, each time t1, t
2 and t3 indicate the point in time when the accelerator opening ACCP is returned to the fully closed state, and the magnitude of the engine speed NE at each of the times t1, t2 and t3 is different. And
As is clear from this figure, each time t1, t2, t3
Reference times TIDL (i), TIDL according to the deviation between the engine speed NE and the target idle speed NF at
The lengths of (i + 1) and TIDL (i + 2) are determined. Then, each reference time TIDL (i), TIDL (i
+1), TIDL (i + 2) and the time required for the engine speed NE to reach the target idle speed NF match, so that when the diesel engine 2 reliably reaches the target idle speed NF, the idle flag FIDL Becomes "1", that is, it is determined that the idle stable state is determined. Thus, the ISC integral control amount NFI
Is also kept constant, and it is understood that learning is not updated unnecessarily to the minus side.

Therefore, even when the integral control amount NFI used for the fuel injection amount control is learned from the ISC as in this embodiment, erroneous learning of the integral control amount NFI can be prevented. In addition, as shown before and after time t3 in FIG. 9, the accelerator opening ACCP changes from a state where the engine speed NE is slightly higher than the target idle speed NF.
Is returned to the fully closed state, the reference time TIDL (i) corresponding to the magnitude of the engine speed NE at that time is used.
+2) is determined and the idling stable state is determined based on the reference time TIDL (i + 2). Therefore, before the reference time TIDL (i + 2) passes, the engine speed NE reaches the target throttle speed NF. And the idle stable state can be accurately determined.
The response delay of control such as C can be eliminated.

It should be noted that the present invention is not limited to the above-described embodiment, and may be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the above embodiment, the equation for calculating the reference time TIDL was set to TIDL = (NE−NF) * 1.1 / 1000. However, the present invention is not limited to this. The value multiplied by the deviation from the target idle speed NF can be changed as appropriate. (2) In the above embodiment, the present invention is embodied in the diesel engine 2 having the turbocharger 48 as a supercharger.
It can be embodied as a diesel engine with a supercharger as a supercharger or a diesel engine without a supercharger.

(3) In the above-described embodiment, the detection of the idling stable state is embodied in the diesel engine 2, but the detection may be embodied in another internal combustion engine such as a gasoline engine.

[0068]

As described above in detail, according to the present invention, an engine which is likely to fluctuate in the determination of the idle state.
When the accelerator is fully closed, the
Large deviation between the engine speed and the specified target idle speed
Set the delay time according to the
Immediate judgment on the vehicle speed
Detection can be performed accurately and its detection frequency
Can be increased.

[Brief description of the drawings]

FIG. 1 shows an embodiment of an ECU embodying the present invention;
Is a flowchart for describing a processing routine for idle stable state detection executed by the CPU.

FIG. 2 is a flowchart illustrating a main routine of a fuel injection amount control process executed by an ECU in one embodiment.

FIG. 3 is a map in which a relationship between a cooling water temperature and a water temperature correction coefficient is determined in one embodiment.

FIG. 4 is a map in which a relationship between an engine speed and a rotation speed correction coefficient is determined in one embodiment.

FIG. 5 is a map in which the relationship between a correction coefficient and an integral control amount learning value is determined in one embodiment.

FIG. 6 is a map in which a relation between a basic maximum injection amount and an engine speed is determined in one embodiment.

FIG. 7 is a map in which the relationship between the engine speed and the maximum injection increase in one embodiment is determined.

FIG. 8 is a map in which a relationship between a supercharging pressure and an intake pressure correction coefficient is determined in one embodiment.

FIG. 9 is a time chart illustrating a relationship among an accelerator opening, an engine speed, an idle flag, and an integral control amount in one embodiment.

FIG. 10 is a schematic configuration diagram showing a fuel injection amount control device for a diesel engine in one embodiment.

FIG. 11 is a sectional view showing a distribution type fuel injection pump in one embodiment.

FIG. 12 is a block diagram illustrating a configuration of an ECU in one embodiment.

FIG. 13 is a time chart illustrating a relationship among an accelerator opening, an engine speed, an idling stable state, and an integrated control amount in a conventional example.

[Explanation of symbols]

1. Fuel injection pump 2. Diesel engine 35.
Revolution speed sensor, 65 starter switch, 68 air conditioner switch, 71 ECU, 73 accelerator opening sensor, 74 intake pressure sensor, 75 water temperature sensor, 77 vehicle speed sensor, TIDL reference time, FIDL idle flag .

Claims (1)

(57) [Claims] When the accelerator opening of an internal combustion engine is fully closed.
From the point, the engine at the time when the accelerator opening is fully closed
Of the deviation between the engine speed and the specified target idle speed
The delay time set in accordance with elapses and the vehicle stops
When the state is detected, an
Dollar state detection method.