JPH04370347A - Crank angle detecting method for engine - Google Patents

Abstract

PURPOSE:To accurately perform time conversion of a surplus angle based on rotational time by improving estimated accuracy of the rotational time in the vicinity of a target spill angle. CONSTITUTION:A number of pulse counts from a certain reference position of engine rotational pulse to a target spill angle corresponding to an injection ending period and a surplus angle less than a 1-pulse amount are obtained, and as a time used for time conversion of this surplus angle, an angle time required for rotating at an equal angle in a preceding time equal crank angle position is corrected by both a change of mean engine speed Nave and a change of instantaneous maximum speed Nmax. Thus, a change of rotational speed (Nmin) in the vicinity of the target spill angle, when only a load is changed, is well represent by a change of the instantaneous maximum rotational speed Nmax, and in the case of decreasing the mean engine speed Nave, its change well represents the change of the rotational speed in the vicinity of the target spill angle. Accordingly, correction of angle time is more accurately performed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crank angle detection method for detecting a crank angle used for arithmetic processing of fuel injection amount control in an engine applied to, for example, an automobile.

0002

[Prior Art] Conventionally, in a fuel injection pump for an electronically controlled diesel engine, a spill port is opened by controlling, for example, an electromagnetic spill valve, etc., so that the fuel injection amount obtained according to the lift of the plunger becomes a target value. I'm trying to open it up. This causes the fuel from the plunger high pressure chamber to overflow (spill) into the fuel chamber, and the pressure of the fuel is completed.
That is, the end of fuel injection is controlled and the required fuel injection amount is controlled.

[0003] In such an electromagnetic spill valve, the target spill angle is normally converted into time using a signal synchronized with the lift of the plunger and input at every fixed pump rotation angle, such as an engine rotation pulse and an average engine rotation speed. A target spill timing is determined based on the target spill timing, and the electromagnetic spill valve is controlled on/off based on the target spill timing. For example, in the fuel injection amount control device disclosed in JP-A-61-118545, in order to obtain the required fuel injection amount, the engine rotation pulse is adjusted based on the engine rotation pulse obtained at each constant crank angle. The number of pulse counts from a certain reference position to the target spill angle and the remainder angle less than one pulse are determined, and the remainder angle is converted into time based on the engine rotation speed to determine the target spill timing. In this case, the engine rotation time is predicted based on the average engine rotation speed between a predetermined crank angle including the previously detected target spill angle,
Based on the predicted rotation time, the remaining angle was converted into time.

0004

However, in the technique disclosed in the above-mentioned prior art publication, when the load on the diesel engine changes, even if the average engine speed does not change,
Alternatively, even if the change is small, the engine rotation speed changes near the target spill angle. That is, as shown in FIG. 11, the instantaneous rotational speed of the diesel engine is not constant over time, and even within one rotation, rotational fluctuations occur with a certain period. In this figure, when the load on the diesel engine increases over time, as is clear from the figure, the rotational fluctuation increases as the load increases even within the same rotation. In this case, the average engine rotational speed Nave shown by the two-dot chain line hardly changes, but the instantaneous minimum rotational speed Nmin near the target spill angle, that is, at the spill pulse time detection position, gradually decreases.

Therefore, even if the instantaneous minimum rotational speed Nmin is actually changing, the average engine rotational speed Nav
Since e hardly changes, the accuracy of the latest spill pulse time to be predicted deteriorates. As a result, there is a fear that the accuracy of time conversion of the above-mentioned remainder angle may deteriorate. This invention was made in view of the above-mentioned circumstances, and its purpose is to reduce the rotation speed near the target crank angle when the instantaneous rotation speed near the target crank angle changes due to changes in engine load. It is an object of the present invention to provide a method for detecting a crank angle of an engine, which is capable of improving time prediction accuracy and thereby converting a remainder angle based on rotation time into time with high precision.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a crank angle detection method that detects the crank angle near the time when the instantaneous engine speed is the lowest. Based on the obtained engine rotation pulse, calculate the number of pulse counts from the reference position of the engine rotation pulse to the target crank angle corresponding to the time to be detected, and the remainder angle less than one pulse, and calculate the remainder angle over time. When converting, the time used for the time conversion is the angular time required to rotate the same angle at the same crank angle position last time, and the angular time obtained is the latest average engine rotation. The corrected angle time is corrected based on the change between the speed and the previous average engine rotational speed, and the corrected angle time is further corrected based on the change between the latest instantaneous maximum rotational speed and the previous instantaneous maximum rotational speed. ing.

[0007]

[Operation] According to the above configuration, the remainder angle is used to convert the time, and the angular time required to rotate the same angle at the same crank angle position in the previous time is calculated based on the latest average engine speed and its Correcting based on the change from the previous average engine rotation speed, that is, the change in the average engine rotation speed,
Further, correction is made based on the change between the latest instantaneous maximum rotational speed and the previous instantaneous maximum rotational speed, that is, the change in the instantaneous maximum rotational speed.

[0008]The change in engine rotational speed near the target crank angle when only the engine load changes is often represented by the change in the instantaneous maximum rotational speed. In addition, when the engine load is constant and the average engine speed decreases, the change in the instantaneous maximum engine speed is small, and the change in engine speed near the target crank angle is due to the change in the average engine speed. Well represented.

Therefore, by correcting the angular time based on both the change in the instantaneous maximum rotational speed and the change in the average engine rotational speed, a more accurate angular time can be obtained.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the engine crank angle detection method of the present invention is applied to a diesel engine will be described in detail below with reference to FIGS. 1 to 10. FIG. 7 is a schematic configuration diagram showing a fuel injection amount control device for a supercharged diesel engine in this embodiment, and FIG. 8 is a sectional view showing the distribution type fuel injection pump 1 thereof. fuel injection pump 1
The engine is equipped with a drive pulley 3 which is drivingly connected to a crankshaft 40 of a 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 each cylinder of the diesel engine 2 (
In this case, each fuel injection nozzle 4 provided for each cylinder (in this case, 4 cylinders)
Fuel is pumped to perform fuel injection.

In the fuel injection pump 1, a drive pulley 3 is attached to the tip of a drive shaft 5. Further, a fuel feed pump 6 (expanded at 90 degrees in this figure), which is a vane type pump, is provided in the middle of the drive shaft 5. Further, a disk-shaped pulser 7 is attached to the base end side of the drive shaft 5. On the outer peripheral surface of this pulser 7, there is a diesel engine 2
The same number of incisors as the number of cylinders, that is, four in this case, are formed at equal angular intervals, and 14 protrusions (56 in total) are formed at equal angular intervals between each incisor. There is. A base end portion of the drive shaft 5 is connected to a cam plate 8 via a coupling (not shown).

A roller ring 9 is provided between the pulser 7 and the cam plate 8, and a plurality of cam rollers 10 are mounted along the circumference of the roller ring 9 to face the cam face 8a of the cam plate 8. There is. cam face 8
The number a is the same as the number of cylinders of the diesel engine 2. Further, the cam plate 8 is always urged into engagement with the cam roller 10 by a spring 11.

The base end of a fuel pressurizing plunger 12 is attached to the cam plate 8 so as to be able to rotate together with the cam plate 8, and 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 engages with the cam roller 10 while rotating, and reciprocates in the left and right directions in the figure by the same number of cylinders. Driven. Further, along with this reciprocating movement, the plunger 12 is rotated and reciprocated in the same direction. In other words,
The plunger 12 is moved forward (lifted) in the process where 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 in the process where the cam face 8a rides down on the cam roller 10.

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 tip surface of the plunger 12 and the bottom surface of the cylinder 14.
It becomes. Moreover, on the outer periphery of the tip side of the plunger 12,
The same number of suction grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine 2 are formed. Also, those suction grooves 16
and corresponding to the distribution port 17, the pump housing 13
A distribution passage 18 and a suction port 19 are formed in the.

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
6 communicates with the suction port 19, fuel is introduced from the fuel chamber 21 into the high pressure chamber 15. 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 is injected.

A spill passage 22 is formed in the pump housing 13 for communicating fuel overflow (spill) between the high pressure chamber 15 and the fuel chamber 21 . An electromagnetic spill valve 23 serving as a spill adjustment valve for adjusting fuel spill from the high pressure chamber 15 is provided in the middle of the spill passage 22 . This electromagnetic spill valve 23 is a normally open type valve, and when the coil 24 is not energized (off), the valve body 25 is opened and the fuel in the high pressure chamber 15 is spilled into the fuel chamber 21 . Further, when the coil 24 is energized (turned on), the valve body 25 is closed and spilling of fuel from the high pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, by controlling the energization time of the electromagnetic spill valve 23, the valve 23 is controlled to close and open, and the spill amount of fuel from the high pressure chamber 15 to the fuel chamber 21 is controlled. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the pressure of the fuel in the high pressure chamber 15 is reduced, and fuel injection from the fuel injection nozzle 4 is stopped. 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, while the plunger 12 is moving forward, the amount of fuel injected from the fuel injection nozzle 4 is controlled by controlling the timing of closing and opening of the electromagnetic spill valve 23.

A timer device 26 (expanded 90 degrees in this figure) is provided on the lower side of the pump housing 13 for adjusting the fuel injection timing. This timer device 26 changes the timing at which the cam face 8a engages with the cam roller 10, that is, the timing at which the cam plate 8 and the plunger 12 are driven back and forth by changing the position of the roller ring 9 with respect to the rotational direction of the drive shaft 5. It is for.

This timer device 26 is hydraulically driven, and includes a timer housing 27, a timer piston 28 fitted in the housing 27, and a low pressure chamber 29 on one side of the timer housing 27. It is composed of a timer spring 31 and the like that press and urge the piston 28 toward the pressurizing chamber 30 on the other side. The timer piston 28 is connected to the roller ring 9 via a slide pin 32.

The pressurizing chamber 30 of the timer housing 27 includes:
Pressurized fuel is introduced by a fuel feed pump 6. The position of the timer piston 28 is determined by the balance between the fuel pressure and the biasing force of the timer spring 31. Furthermore, by determining the position of the timer piston 28, the position of the roller ring 9 is determined, and the plunger 1 is moved through the cam plate 8.
2 reciprocating timing is determined.

A timing control valve 33 is provided in the timer device 26 in order to adjust the fuel pressure of the timer device 26, that is, the control oil pressure. That is, the pressurizing chamber 30 and the low pressure chamber 29 of the timer housing 27 are connected to the communication passage 34.
A timing control valve 33 is provided in the middle of 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 within the pressurizing chamber 30 is adjusted by opening and closing the timing control valve 33. By adjusting the fuel pressure, the lift timing of the plunger 12 is controlled, and the timing of fuel injection from each fuel injection nozzle 4 is adjusted.

A rotation speed sensor 35 consisting of an electromagnetic pickup coil is attached to the upper part of the roller ring 9 so as to face the outer peripheral surface of the pulser 7. This rotation speed sensor 35
is a timing signal corresponding to the engine rotation speed NE by detecting the passage of protrusions, etc. of the pulser 7 when they cross, that is, an engine rotation pulse as a rotation angle signal for each predetermined crank angle (11.25° CA). Output. Furthermore, since the rotation speed sensor 35 is integrated with the roller ring 9, it 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 explained. In this diesel engine 2, a main combustion chamber 44 corresponding to each cylinder is formed by a cylinder 41, a piston 42, and a cylinder head 43, respectively. or,
Each of the main combustion chambers 44 is connected to a sub-combustion chamber 45 corresponding to each cylinder. Then, 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 starting aid 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 copresor 49 of a turbocharger 48 constituting a supercharger, and the exhaust pipe 50 is provided with a turbocharger 49. 48
A turbine 51 is provided. Further, the exhaust pipe 50 is provided with a waste gate valve 5 for adjusting the supercharging pressure PiM.
2 is provided. As is well known, the turbocharger 48 uses the energy of exhaust gas to rotate the turbine 51, and rotates the compressor 49 coaxially therewith to increase the pressure of intake air. This allows a high-density air-fuel mixture to be sent into the main combustion chamber 44 to combust a large amount of fuel, thereby increasing the output of the diesel engine 2.

The diesel engine 2 also has an exhaust pipe 5.
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in the exhaust gas into the intake port 53 of the intake pipe 47. An exhaust gas recirculation valve (EGR valve) 55 is provided in the middle of the recirculation pipe 54 to adjust the amount of recirculation of exhaust gas. This EGR valve 55 is controlled to open and close by controlling a vacuum switching valve (VSV) 56.

Further, a throttle valve 58 is provided in the middle of the intake pipe 47 and is opened and closed in conjunction with the amount of depression of the accelerator pedal 57. Also, the throttle valve 5
A bypass passage 59 is provided in parallel to 8, and a bypass throttle valve 60 is provided in the bypass passage 59. This bypass throttle valve 60 is controlled to open and close by an actuator 63 having a two-stage diaphragm chamber driven by the control of two VSVs 61 and 62. This bypass throttle valve 60 is controlled to open and close depending on various operating conditions. For example, during idling operation, it is controlled to a half-open state to reduce noise and vibration, etc., during normal operation, it is controlled to a fully open state, and when the operation is stopped, it is controlled to a fully closed state to ensure a smooth stop.

As described above, the electromagnetic spill valve 23 provided in the fuel injection pump 1 and the diesel engine 2
, timing control valve 33, glow plug 4
6 and each of the VSVs 56, 61, and 62 are electrically connected to an electronic control unit (hereinafter simply referred to as "ECU") 71, and their drive timings are controlled by the ECU 71.

In addition to the rotational speed sensor 35, the following various sensors are provided as sensors for detecting the operating state. That is, the intake pipe 47 is provided with an intake temperature sensor 72 that detects the intake air temperature THA in the vicinity of the air cleaner 64. Further, an accelerator opening sensor 73 is provided that detects an accelerator opening ACCP corresponding to the load of the diesel engine 2 from the opening/closing position of the throttle valve 58. An intake pressure sensor 74 is provided near the intake port 53 to detect the intake air pressure after supercharging by the turbocharger 48, that is, the supercharging pressure PiM. 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 is provided that detects the rotational position of the crankshaft 40 of the diesel engine 2 with respect to a rotational reference position, for example, the top dead center of a specific cylinder. Furthermore, the transmission (not shown) is provided with a vehicle speed sensor 77 that detects vehicle speed SP by turning on and off a reed switch 77b using a magnet 77a rotated by the rotation of the gear.

The above-mentioned sensors 72 to 77 are connected to the ECU 71, and the rotation speed sensor 3 is also connected to the ECU 71.
5 is connected. In addition, the ECU 71 has each sensor 35,
Based on the signals output from 72 to 77, the electromagnetic spill valve 23, timing control valve 33, glow plug 46, VSV 56, 61, 62, etc. are suitably controlled.

Next, the configuration of the ECU 71 mentioned above will be explained with reference to the block diagram shown in FIG. The ECU 71 includes a central processing unit (CPU) 81 and a read-only memory (ROM) that stores predetermined control programs, maps, etc.
82, a random access memory (RAM) 83 for temporarily storing calculation results etc. of the CPU 81, a backup RAM 84 for storing pre-stored data, etc., and each of these parts and an input port 85, an output port 86, etc. are connected by a bus 87. It is configured as a logic operation circuit.

The input port 85 has the aforementioned intake temperature sensor 72, accelerator opening sensor 73, intake pressure sensor 74, and water temperature sensor 75 connected to each buffer 88, 89, 90, 9.
1, connected via a multiplexer 93 and an A/D converter 94. Similarly, the aforementioned rotation speed sensor 35, crank angle sensor 76, and vehicle speed sensor 77 are connected to the input port 85 via a waveform shaping circuit 95. Then, the CPU 81 reads detection signals from the sensors 35, 72 to 77, etc. inputted through the input port 85 as input values. Further, each drive circuit 96 is connected to the output port 86.
, 97, 98, 99, 100, 101, the electromagnetic spill valve 23, timing control valve 33, glow plug 46, VSV 56, 61, 62, etc. are connected.

[0032]The CPU 81 then controls each sensor 35, 72.
Based on the input value read from ~77, the electromagnetic spill valve 2
3. Suitably controls the timing control valve 33, glow plug 46, VSV 56, 61, 62, etc. Next, the crank angle detection processing operation and the fuel injection amount control processing operation executed by the ECU 71 described above will be described with reference to FIGS. 1 to 6 and 10.

First, FIG. 1 shows a flowchart of the ECU 71.
Among the processes executed by the above, the NE interrupt routine is interrupted at the rising edge of the engine rotation pulse of the engine rotation speed NE input from the rotation speed sensor 35. When the process moves to this routine, first in step 101, the difference between the current time FC, which is the count value of the free running counter, and the interrupt time T0, which corresponds to the current time at the time of the previous NE interrupt, is set as the pulse time TNINT. do. That is, as shown in the time chart of FIG. 2, the time required to advance by a crank angle (11.25° CA) corresponding to one engine rotation pulse is calculated.

Next, in step 102, it is determined whether the current interrupt pulse signal is a reference position signal. That is, the pulse time TN calculated in step 101
INT(i) is the previously calculated pulse time TNINT
Compare whether it is 1.5 times or more of (i-1) and
1.5 times" or more, it is determined that the signal is the reference position signal in FIG. 2. Here, if it is the reference position signal, in step 103, the pulse counter CNI
After resetting the value of RQ to "0", the process moves to step 104. If it is not the reference position signal, the process directly proceeds to step 104.

Proceeding from step 102 or step 103, in step 104, the current time FC in step 101 is set as the interrupt time T0. Subsequently, in step 105, the pulse counter C
It is determined whether the value of NIRQ is "3", that is, whether the rotational speed is near the maximum rotation speed as shown in FIG. Here, if the value of the pulse counter CNIRQ is "3", in step 106, the time T23 ( i), the time T2 at the previous instantaneous maximum rotational speed Nmax
3(i-1). Incidentally, this time T23 means that the crank angle is 11.25° CA from when the value of the pulse counter CNIRQ becomes "2" until it becomes "3".
This corresponds to the pulse time TNINT required to advance by ''.

Then, in step 107, the pulse time TNINT obtained in step 101 is set as the time T23(i) at the current instantaneous maximum rotational speed Nmax, and the subsequent processing is temporarily terminated. On the other hand, if the value of the pulse counter CNIRQ is not "3" in step 105, it is determined in step 108 whether the value of the pulse counter CNIRQ is "8". Here, the value of pulse counter CNIRQ is "8".
If so, in step 109, the time T1 at the average engine speed Nave set when the value of the pulse counter CNIRQ was "8" last time is
80(i) as the previous average engine speed Na
ve is set as time T180(i-1). Note that this time T180 is the pulse counter CNIRQ.
This is the time required for the crank angle to advance by "180° CA" from when the value was "8" last time until it becomes "8" this time, and is counted by the free running counter.

Then, in step 110, the time T at the average engine speed Nave set when the value of the pulse counter CNIRQ reached "8" last time is determined.
The difference between the value of 180S and the value of current time FC, which is now "8", is set as time T180(i) at the new average engine rotational speed Nave. After that, in step 111, when the value of the pulse counter CNIRQ becomes "8" next time, the average engine rotation speed Nave
In order to calculate time T180(i) at , the value of current time FC is newly set as time T180S at average engine rotational speed Nave, and the subsequent processing is temporarily terminated.

On the other hand, if the value of the pulse counter CNIRQ is not "8" in step 108, the value of the pulse counter CNIRQ is not "8" in step 112.
10". Here, if the value of the pulse counter CNIRQ is "10", in step 113 the pulse time TNINT previously obtained in step 101 is converted to the spill pulse time TS112.
5, and the subsequent processing is temporarily terminated. That is,
As shown in FIG. 2, the spill pulse time TS1125 is 11.25°C at the crank angle from when the value of the pulse counter CNIRQ reaches "9" until it reaches "10".
This corresponds to the pulse time TNINT required for the fuel to advance by "A", and corresponds to the time when fuel is spilled. Also, if the value of the pulse counter CNIRQ is not "10",
The subsequent processing is then terminated.

Next, FIGS. 3 to 6 show processing operations for fuel injection amount control performed using the spill pulse time TS1125 obtained in the NE interrupt routine as described above.
Explain according to the following. The flowchart shown in Figure 3 is
Among the processes executed by 71, the fuel injection pump 1
This is the main routine for controlling the fuel injection amount in the routine, and is executed by a regular interrupt at every predetermined time.

When the process shifts to this routine, first in step 201, the engine rotation speed NE, accelerator opening ACCP, and cooling water temperature are determined based on the detected values of the rotation speed sensor 35, accelerator opening sensor 73, and water temperature sensor 75. Load each THW. Next, step 20
2, the accelerator opening ACCP and cooling water temperature T
The HW calculates the corrected accelerator opening degree ACCPA. This corrected accelerator opening ACCPA is the cooling water temperature THW.
Pseudo accelerator opening at start-up required according to ACSTA
This is determined by comparing the accelerator opening degree ACCP and the like.

Next, in step 203, the previously read engine speed NE and corrected accelerator opening degree A
Calculate the final injection amount QFIN based on CCPA etc. This final injection amount QFIN is determined according to the following calculation formula (1). Note that "C1, C2, and C3" in the formula are constants. QFIN=C1+C2×ACCPA×
C3×NE (1) Next, in step 204, a low rotation increase correction coefficient KAVT is calculated in order to perform increase correction at low rotation to prevent the diesel engine 2 from stalling in the low rotation range. This low rotation increase correction coefficient KAVT is determined by referring to a predetermined map (not shown).

Then, in step 205, the number of spill timing pulses CANGLa and the remainder angle θREMa are calculated from the final injection amount QFIN obtained previously. The number of spill timing pulses CANGLa and the remainder angle θREMa are obtained with reference to the following calculation formula (2). QFIN=11.25×CANGLa
+θREMa...(2) In other words, as shown in FIG.
Divide the final injection amount QFIN by "11.25", which corresponds to the angle of one engine rotation pulse, find the quotient as the number of spill timing pulses CANGLa, and find and set the remainder as the remainder angle θREMa. . Here, the spill timing pulse number CANGLa corresponds to the engine rotation pulse number corresponding to the spill timing at which the electromagnetic spill valve 23 should be turned off to end fuel injection, that is, the fuel should be spilled ("9" in FIG. 4). ). In addition, the remainder angle θREMa is the number of pulses at the spill period CANGLa.
This is a value that indicates the more precise spill timing in degrees.

Next, in step 206, the corrected spill pulse time TS1125A is calculated. This corrected spill time pulse time TS1125A is the above-mentioned N
Spill pulse time TS1125, time T180(i), T180(i-1) at average engine rotational speed Nave, and time T23(i), T23( at instantaneous maximum rotational speed Nmax) obtained in E interrupt routine.
i-1) with reference to the following calculation formula (3).

TS1125A=TS1125×(T180(i)
/T180(i-1))
×(T23(i-1)/T23(i))...
(3) That is, in this calculation formula, the time T180(i) at the latest average engine rotational speed Nave and the time T180(i) at the previous average engine rotational speed Nave
−1) and the time T23(i) at the latest instantaneous maximum rotational speed Nmax and the previous instantaneous maximum rotational speed N
The spill pulse time TS1125 is corrected by multiplying the ratio by the time T23(i-1) at max.

Thereafter, in step 207, a low rotation increase correction coefficient KV is applied to the previously determined surplus angle θREMa.
The result of multiplication by AT is set as the final remainder angle θREM. That is, the low rotation increase correction coefficient KVAT is reflected in the final surplus angle θREM, and when a low rotation increase is required, a value corresponding to the increase is set. Subsequently, in step 208, the previously determined final remainder angle θREM
and the corrected spill pulse time TS1125A,
Spill time T at spill time pulse number CANGLa
Calculate SPONa. That is, the final remainder angle θREM is converted into time. This spill time TSPONa is determined according to the following calculation formula (4).

TSPONa=(θREM/11.25)×T
S1125A...(4) Then, in step 209, in consideration of the calculation processing speed of the ECU 71, the spill time TSPO is set to prevent delays due to multiple interrupts.
It is determined whether Na is smaller than a predetermined value of "100 μs". Here, the spill time TSPONa is set to a predetermined value of "10".
0 μs”, in step 210, as shown in FIG. 5, the result of adding the corrected spill pulse time TS1125A to the spill time TSPONa is set as the final spill time TSPON. Also, in the same step 113, the number of spill timing pulses CANGLa
The result of subtracting "1" from the number is set as the final spill timing pulse number CANGL.

Then, in step 211, the electromagnetic spill valve 23 is turned off based on the set final spill timing pulse number CANGL and final spill time TSPON, and the end timing of fuel injection from the fuel injection pump 1, that is, the fuel injection amount is determined. control and temporarily end the subsequent processing. On the other hand, in step 209, the spill time TSPONa
is equal to or greater than the predetermined "100 μs", in step 212, as shown in FIG. 6, the spill time TSP
ONa is directly set as the final spill time TSPON. In addition, in the same step 212, the number of spill timing pulses CANGLa is directly changed to the final number of spill timing pulses C.
Set as ANGL.

Then, in step 211, based on the set final spill timing pulse number CANGL and final spill time TSPON, the electromagnetic spill valve 23 is turned off, and the end timing of fuel injection from the fuel injection pump 1 is determined.
That is, the fuel injection amount is controlled and the subsequent processing is temporarily terminated. The fuel injection amount control of the diesel engine 2 is executed as explained above. In this embodiment, in order to convert the final surplus angle θREM into time, the pulse time TS1125 of the previous spill near the target spill angle is simply used.
Instead of using the pulse time TS1 when spilling
Corrected spill pulse time TS112 after correcting 125
I am using 5A. Moreover, the pulse time TS at the time of spill
1125 is the ratio of time T180(i) at the latest average engine rotational speed Nave to time T180(i-1) at the previous average engine rotational speed Nave,
Time T23 at the latest instantaneous maximum rotational speed Nmax (
The corrected spill pulse time TS1125A is obtained by correcting both the ratio of i) and the time T23(i-1) at the previous instantaneous maximum rotational speed Nmax. That is, the spill pulse time TS1125 is corrected by a change in time T180 at the average engine rotational speed Nave and a change in time T23 at the instantaneous maximum rotational speed Nmax.

Here, as shown in FIG. 10 showing the time change in the instantaneous rotational speed, the rotational speed near the target spill angle when only the load of the diesel engine 2 changes, that is, the rotational speed at the detection position of the spill pulse time TS1125. It is known that the change in the instantaneous minimum rotational speed Nmin (indicated by a broken line in the figure) is well represented by the change in the instantaneous maximum rotational speed Nmax (indicated by a dashed-dotted line in the figure).

Furthermore, when the load on the diesel engine 2 is constant and the average engine rotational speed Nave (shown by a two-dot chain line in the figure) decreases, the instantaneous maximum rotational speed Nm
ax does not change much. On the other hand, it is known that the change in the instantaneous minimum rotational speed Nmin at the detection position of the spill pulse time TS1125 is well represented by the change in the average engine rotational speed Nave.

Therefore, by correcting the uniformly determined spill pulse time TS1125 based on both the change in the instantaneous maximum rotational speed Nmax and the change in the average engine rotational speed Nave, an appropriate spill pulse time after correction is always obtained. Time TS1125A can be determined. That is, when the instantaneous rotational speed near the target spill angle changes due to a change in the load of the diesel engine 2, the rotation time near the target spill angle can be accurately predicted.

Therefore, since the final remainder angle θREM is converted into time using the appropriate corrected spill pulse time TS1125A, the time conversion can be performed with high precision. As a result, the fuel spill timing can be determined more accurately, and the fuel injection amount can be controlled with high precision. It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be implemented as follows by changing a part of the structure as appropriate without departing from the spirit of the invention.

(1) In the above embodiment, in order to calculate the corrected spill pulse time TS1125A, some of these current and previous changes are used as substitute values for the changes in the average engine speed Nave and the instantaneous maximum engine speed Nmax. Required time T180(i), T180(i-1), T2
3(i), T23(i-1), the current and previous average engine rotational speed Nave(i), (i-1) and the instantaneous maximum rotational speed Nm
It is also possible to follow the following calculation formula (5) using ax(i) and (i-1).

TS1125A=TS1125×(Nave(i−
1)/Nave(i))
×(Nmax(i)/Nmax(i-1))
... (5) (2) In the above embodiment, the explanation has been given concretely to the fuel injection amount control of the diesel engine 2, but it can also be applied to, for example, detecting the crank angle near the target ignition timing of a gasoline engine. You can also.

[0055]

As detailed above, according to the present invention, the angular time required to rotate the same angle at the same crank angle position last time is used to convert the residual angle into time. Since the correction is made based on the change between the latest average engine rotation speed and the previous average engine rotation speed, and further based on the change between the latest instantaneous maximum rotation speed and the previous instantaneous maximum rotation speed, To be able to correct the angle time with higher precision, and to improve the prediction accuracy of the rotation time near the target crank angle when the instantaneous rotation speed near the target crank angle changes due to a change in engine load. This provides an excellent effect in that the remainder angle based on the rotation time can be converted into time with high accuracy.

[Brief explanation of the drawing]

[Fig. 1] In one embodiment embodying this invention, an ECU
2 is a flowchart illustrating an NE interrupt routine that is executed by and interrupted at the rising edge of an engine rotation pulse.

FIG. 2 is a time chart illustrating the correspondence between changes in engine rotation speed and engine rotation pulses in one embodiment.

FIG. 3 is a flowchart illustrating a main routine for fuel injection amount control executed by an ECU in one embodiment.

FIG. 4 is a time chart illustrating the correspondence between engine rotation pulses and electromagnetic spill valve operation, the number of spill timing pulses, the remainder angle, etc. according to the final injection amount in one embodiment.

FIG. 5 is a time chart illustrating the correspondence between the engine rotation pulse and the electromagnetic spill valve operation, the final spill timing pulse number, the final spill time, etc. when the spill time is smaller than 100 μs in one embodiment.

FIG. 6 is a time chart illustrating the correspondence between the engine rotation pulse and the operation of the electromagnetic spill valve, the final spill timing pulse number, the final spill time, etc. when the spill time is 100 μs or more in one embodiment.

FIG. 7 is a schematic configuration diagram illustrating a fuel injection amount control device for a supercharged diesel engine in one embodiment.

FIG. 8 is a sectional view showing a fuel injection pump in one embodiment.

FIG. 9 is a block diagram showing the configuration of an ECU in one embodiment.

FIG. 10 is an explanatory diagram illustrating changes in the instantaneous maximum rotational speed, average engine rotational speed, and instantaneous minimum rotational speed in the temporal change in the instantaneous rotational speed of the diesel engine in one embodiment.

FIG. 11 is an explanatory diagram illustrating changes in the instantaneous maximum rotational speed, average engine rotational speed, and instantaneous minimum rotational speed in the temporal change in the instantaneous rotational speed of a diesel engine in a conventional example.

[Explanation of symbols]

1...Fuel injection pump, 2...Diesel engine, 35...
Rotation speed sensor, 71...ECU, 73...Accelerator opening sensor, 75...Water temperature sensor, TS1125...Pulse time at spill, TS1125A...Pulse time at spill after correction, T
23, T23(i), T23(i-1)...Time at instantaneous maximum rotational speed, T180, T180(i), T18
0(i-1)...Time at average engine speed, θ
REM...Final remainder angle.

Claims (1)

[Claims] Claim 1: A crank angle detection method for detecting a crank angle near the time when the instantaneous engine rotational speed is the lowest, based on an engine rotational pulse obtained at each constant crank angle, from a reference position where the engine rotational pulse is located. When calculating the number of pulse counts up to the target crank angle corresponding to the time to be detected and the remaining angle that is less than one pulse, and converting the remaining angle into time, use the previous time as the time used for the time conversion. The angular time required to rotate the same angle at the same crank angular position is calculated, and the calculated angular time is corrected based on the change between the latest average engine speed and the previous average engine speed. A method for detecting a crank angle of an engine, characterized in that the corrected angle time is further corrected based on a change between the latest instantaneous maximum rotational speed and the previous instantaneous maximum rotational speed.