JPH051603A - Idle rotation control device for the diesel engine - Google Patents

Abstract

(57) [Summary] [Purpose] When returning from the idle-up mode to the normal idle mode, the actual rotation speed is higher than the target rotation speed during normal idle even if the fuel temperature rises due to changes in operating conditions over time. It also prevents it from falling too low. [Structure] The idle rotation control device includes a rotation speed sensor 35,
The electromagnetic spill valve 23, the air conditioner switch 65, the neutral switch 66, the water temperature sensor 75, the idle up switch 67, etc. are provided. The CPU controls the electromagnetic spill valve 23 so that the actual rotation speed becomes the target rotation speed by the feedback control using the integral control amount and the expected control amount. When returning from the idle-up mode to the normal idle mode, the CPU corrects the integrated control amount at the time of normal idle immediately before the start of idle-up based on the change amount of the integrated control amount at idle-up, This is the initial value of the integrated control amount during normal idle this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine idle speed control device, and more particularly, to adjusting a fuel injection amount of a fuel injection pump of a diesel engine to set an engine speed at idle to a target speed. The present invention relates to a diesel engine idle speed control device that is matched.

[0002]

2. Description of the Related Art Conventionally, as a technique for controlling the rotational speed of a diesel engine of this type during idling, there is, for example, one disclosed in Japanese Patent Laid-Open No. 181940/1982. In this technique, first, a target rotation speed NF according to the operating state of the diesel engine is calculated, and the integral control amount NFI is obtained based on the difference between the target rotation speed NF and the actual rotation speed NEQB. Further, the expected control amount NFP according to the load change of the automatic transmission (torque converter), the air conditioner (air conditioner), etc. is obtained. Then, the integrated control amount NFI and the expected control amount NFP are subtracted from the actual rotation speed NEQB to obtain a deviation (correction rotation speed) NEISC, and the governor pattern is moved by changing the correction rotation speed NEISC to obtain the actual rotation speed. The NEQB is controlled so as to match the target rotation speed NF.

Such an idle rotation control is performed not only during normal idling, but also during idling up in which the rotation speed is increased by a predetermined amount from the normal idling in order to improve the effectiveness of the air conditioner. The same is done. Then, the change from the normal idle state to the idle-up state, or the change from the idle-up state to the normal idle state, for example, the switch for idle-up is turned on and the idle-up operating condition is satisfied. Or when the switch is turned off and the idle-up stop condition is satisfied.

According to the above-mentioned technique, the rotational speed at the time of normal idle or idle-up is operated regardless of variations among fuel injection pumps, magnitude of engine load, change over time, etc., and without using a special actuator. The target rotation speed can be controlled according to.

[0005]

However, in the above-mentioned prior art, when the actual rotation speed NEQB is controlled to the target rotation speed NF at the time of idling up, the actual rotation speed NEQB is returned to the target rotation speed NF at the time of normal idling. However, the actual rotation speed NEQB may be temporarily lower than the target rotation speed NF during the normal idling.

This is because of the following reasons. Before the idling-up operation condition is satisfied and the actual rotation speed NEQB rises, the integral control amount NFI for maintaining the actual rotation speed NEQB at the target rotation speed NF during normal idle (for example, 800 rpm) is calculated, and is set to that value. The fuel injection amount is controlled based on this. When the idle-up operation condition is satisfied from this state, the integral control amount NF for stabilizing the actual rotation speed NEQB to the target rotation speed NF (for example, 1200 rpm) higher than the target rotation speed NF at the time of normal idle.
I is calculated, and the fuel injection amount is controlled based on the calculated value.

When the control for achieving the target rotational speed NF at the time of idling is continued, the fuel temperature gradually rises due to the change over time in the operating condition. Since the fuel injection amount relatively decreases when the fuel temperature rises in this way, the integral control amount NFI is increased in order to keep the actual rotation speed NEQB at the same target rotation speed NF at the time of idling up. The command value for the fuel injection amount must be increased.

Further, the decrease amount of the actual fuel injection amount due to the rise of the fuel temperature is not constant regardless of the actual rotation speed NEQB of the diesel engine, but increases as the actual rotation speed NEQB decreases. There is. As a result, the amount of increase in the integrated control amount NFI for compensating for the decrease in the actual fuel injection amount needs to be larger in the normal idle time than in the idle up time.

Therefore, the idle-up stop condition is satisfied from the idle-up state, and the actual rotation speed NEQB
When the final integrated control amount NFI in the idle-up state is used as it is as the initial value of the integrated control amount NFI when returning to the target rotational speed NF during normal idle, the injection amount decreases due to the increase in the fuel temperature during normal idle. The minute cannot be compensated by the integral control amount NFI.
As a result, the actual rotation speed NEQB cannot be maintained at the target rotation speed NF during normal idling, and
There was a case where the EQB was temporarily lower than the target rotation speed NF during normal idle (undershoot).

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to increase the fuel temperature due to a change with time of operating conditions when returning from an idle-up state to a normal idle state. Another object of the present invention is to provide an idle speed control device for a diesel engine that can prevent the actual speed from falling below the target speed during normal idle.

[0011]

In order to achieve the above object, in the present invention, as shown in FIG. 1, the rotational speed of the diesel engine M1 is adjusted by adjusting the fuel injection amount to the diesel engine M1. Rotational speed adjusting means M2 for adjusting the rotational speed of the diesel engine M1, rotational speed detecting means M3 for detecting the rotational speed of the diesel engine M1, and operating state detecting means M for detecting the operating state of the diesel engine M1.
4, target rotation speed setting means M5 for setting a target rotation speed according to the operating state of the diesel engine M1 by the operating state detecting means M4, and the diesel engine M
No. 1 mode change detection means M6 for detecting the transition from the normal idle mode to the idle up mode or the return from the idle up mode to the normal idle mode, and the target rotation when the mode change is detected by the mode change detection means M6. The set rotation speed changing means M7 for forcibly increasing or decreasing the target rotation speed by the speed setting means M5 by a predetermined amount and the rotation speed by the rotation speed detecting means M3 are raised or lowered by the set rotation speed changing means M7. The rotation speed adjusting means M2 is controlled by feedback control using an integral control amount so that the target rotation speed is achieved.
And a rotation speed control means M8 for controlling the rotation speed, and an integral control amount at the time of normal idle immediately before the start of idle up at the time of returning from the idle up mode to the normal idle mode.
There is provided initial value setting means M9 for making an initial value of the integrated control amount at the time of normal idle this time, by correcting based on the change amount of the integrated control amount at the rotation speed control means M8 at the time of idling up.

[0012]

According to the above construction, the diesel engine M1
The rotation speed of is detected by the rotation speed detecting means M3. When the operating state of the diesel engine M1 is detected by the operating state detecting means M4, the target rotational speed according to the operating state is set by the target rotational speed setting means M5. And the diesel engine M
When the mode change detecting means M6 detects the transition from the normal idle mode to the idle up mode or the return from the idle up mode to the normal idle mode of No. 1, the set rotation speed changing means M7 is the target rotation speed setting means M5.
The target rotation speed is forcedly increased or decreased by a predetermined amount.

The rotation speed control means M8 performs feedback control by an integral control amount so that the rotation speed detected by the rotation speed detection means M3 becomes the target rotation speed changed by the set rotation speed changing means M7. The rotation speed adjusting means M2 is controlled. Then, when returning from the idle-up mode to the normal idle mode, the initial value setting means M9 sets the integral control amount at the time of normal idle immediately before the start of idle-up by the rotation speed control means M8 at idle-up. It is corrected based on the change amount of the integrated control amount to be the initial value of the integrated control amount at the time of the normal idle this time.

In the idle speed control, the change in the integrated control amount at the time of idling up represents the rise in the fuel temperature at the idling up, and this is used to calculate the integrated control amount at the normal idling this time. It is reflected. Therefore, the idle rotation control is performed with the integrated control amount according to the fuel temperature and the target rotation speed NF at the current normal idle time.

Therefore, when the fuel temperature rises at idle-up and the normal idle mode is restored from this state, the decrease in the fuel injection amount due to the rise in fuel temperature becomes larger than that at idle-up. Regardless, it is possible to compensate for the decrease with the integral control amount set as described above.

[0016]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing a schematic configuration of a diesel engine 2 with a supercharger provided with the idle rotation control device of the present embodiment, and FIG. 3 is a sectional view of the distribution type fuel injection pump 1. The fuel injection pump 1 includes a drive pulley 3 drivingly connected to a crankshaft 40 of the diesel engine 2 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 pressure-fed to the fuel injection nozzle 4 provided for each cylinder of the diesel engine 2 to inject the fuel.

The drive pulley 5 has a drive shaft 5
Is connected to the drive shaft 5. A fuel feed pump (developed by 90 degrees in the figure) 6 composed of a vane type pump, and a disk-shaped pulsar 7 having a plurality of protrusions on its outer peripheral surface are connected to the drive shaft 5. Installed. The base end portion (right end portion in the drawing) 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,
A plurality of cam rollers 10 facing the cam face 8 a of the cam plate 8 are attached to the roller ring 9. The cam plate 8 is constantly urged and engaged with the cam roller 10 by the spring 11.

A fuel pressurizing plunger 12 is integrally rotatably attached to the cam plate 8, and the rotational force of the drive shaft 5 is transmitted to the cam plate 8 through a coupling, whereby the cam plate 8 is rotated. Also, the plunger 12 is reciprocally driven in the left-right direction in the drawing while rotating. 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 end surface (the right end surface in the drawing) of the plunger 12 and the inner bottom surface of the cylinder 14. The same number of suction grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine 2 are formed on the outer periphery of the plunger 12 on the front end side. A distribution passage 18 and a suction port 19 are formed in the pump housing 13 so as to correspond to the suction groove 16 and the distribution port 17.

When the fuel feed pump 6 is driven based on the rotation of the drive shaft 5, fuel from a fuel tank (not shown) is supplied into the fuel chamber 21 through the fuel supply port 20. Further, in the intake stroke in which the plunger 12 moves (returns) in the left direction in the drawing and the high pressure chamber 15 is decompressed, one of the intake grooves 16 communicates with the intake port 19 to move from the fuel chamber 21 to the high pressure chamber 15. Fuel is introduced into. On the other hand, the plunger 12 moves to the right in the figure (forward movement).
Then, in the compression stroke in which 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 has a fuel overflow spill passage 22 for communicating the high pressure chamber 15 and the fuel chamber 21.
Is formed, and an electromagnetic spill valve 23 as a rotation speed adjusting means is provided in the middle thereof. This electromagnetic spill valve 2
Reference numeral 3 is a normally open valve, and when the coil 24 is in a non-energized (off) state, the valve body 25 is opened and the fuel in the high pressure chamber 15 overflows into the fuel chamber 21. Further, when the coil 24 is energized (turned on), the valve body 25 is closed and the high pressure chamber 1
The overflow of fuel from 5 to the fuel chamber 21 is stopped.

Therefore, by controlling the energizing time of the electromagnetic spill valve 23, the electromagnetic spill valve 23 is controlled to be closed / opened, and the overflow of the 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 fuel inside the high pressure chamber 15 is depressurized and the fuel injection from the fuel injection nozzle 4 is stopped. In other words, even if the plunger 12 moves forward, the high pressure chamber 15 remains open while the electromagnetic spill valve 23 is open.
The internal fuel pressure does not rise, and fuel injection from the fuel injection nozzle 4 is not performed. Also, during the forward movement of the plunger 12,
The fuel injection amount from the fuel injection nozzle 4 is controlled by controlling the closing / opening timing of the electromagnetic spill valve 23.

Below the pump housing 13, a timer device (90 degrees expanded in the figure) 26 for controlling fuel injection timing is provided. The timer device 26 controls the position of the roller ring 9 with respect to the rotation direction of the drive shaft 5 to control the timing when the cam face 8a engages with the cam roller 10, that is, the reciprocating timing of the cam plate 8 and the plunger 12. Is.

The timer device 26 is operated by hydraulic pressure, and includes a timer housing 27, a timer piston 28 fitted in the timer housing 27, and a low pressure chamber 29 on one side of the timer housing 27. The timer piston 28 is composed of a timer spring 31 and the like for pressing and urging the timer piston 28 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.

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 equilibrium relationship 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 inserted via the cam plate 8.
The reciprocating timing of 2 is determined.

In order to control the fuel pressure of the timer device 26, a timing control valve 33 is provided in a communication passage 34 connecting the pressurizing chamber 30 and the low pressure chamber 29. The timing control valve 33 is an electromagnetic valve whose opening and closing is controlled by a duty-controlled energization signal, and the fuel pressure in the pressurizing chamber 30 is adjusted by the opening and closing control of the timing control 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 as a rotation speed detecting means composed of an electromagnetic pickup coil is attached so as to face the outer peripheral surface of the pulsar 7. The rotation speed sensor 35 detects passage of the protrusions of the pulsar 7 or the like when they cross each other, and outputs a timing signal (engine rotation pulse) corresponding to the engine rotation speed. Further, since this 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 described. As shown in FIG. 2, in the diesel engine 2, the cylinder 41, the piston 42, and the cylinder head 43.
A main combustion chamber 44 corresponding to each cylinder is formed. Further, each of the main combustion chambers 44 is connected to an auxiliary combustion chamber 45 that is also provided corresponding to each cylinder. Then, the fuel injection nozzles 4 are provided in the auxiliary combustion chambers 45.
The fuel injected from is supplied. In addition, each sub-combustion chamber 4
5 is a well-known glow plug 46 as a start assist device.
Are installed respectively.

An intake pipe 47 and an exhaust pipe 50 are connected to the diesel engine 2, a compressor 49 of a turbocharger 48 is arranged in the intake pipe 47, and a turbine 51 of the turbocharger 48 is arranged in the exhaust pipe 50. It is set up. A waste gate valve 52 for adjusting the boost pressure is attached to the exhaust pipe 50.

Further, the diesel engine 2 is provided with a recirculation pipe 54 for recirculating a part of the exhaust gas in the exhaust pipe 50 to the intake port 53 of the intake pipe 47. Reflux pipe 5
In the middle of 4, EGR valve 55 for adjusting the exhaust gas recirculation amount
The EGR valve 55 is controlled to be opened / closed by controlling a vacuum switching valve (VSV) 56.

Further, in the middle of the intake pipe 47, a throttle valve 58 which is opened / closed in association with the depression amount of the accelerator pedal 57 is provided. Further, a bypass passage 59 is formed in parallel with the throttle valve 58, and a bypass throttle valve 60 whose opening / closing is controlled by an actuator 63 according to various operating states is provided in the middle of the bypass passage 59. The actuator 63 is driven by the control of the two VSVs 61 and 62.

The electromagnetic spill valve 2 provided on the fuel injection pump 1 and the diesel engine 2 as described above.
3, the timing control valve 33, the glow plug 46, and the VSVs 56, 61, 62 are electrically connected to an electronic control unit (hereinafter simply referred to as “ECU”) 71, and the drive timings thereof are controlled by the ECU 71. ..

In addition to the rotation speed sensor 35, the following sensors are provided as sensors for detecting the operating state of the diesel engine 2 and the running state of a vehicle equipped with the diesel engine 2. That is, the intake air temperature sensor 72 that detects the intake air temperature of the air drawn into the intake pipe 47 via the air cleaner 64, and the accelerator opening degree that detects the accelerator opening degree ACC corresponding to the load of the diesel engine 2 from the opening / closing position of the throttle valve 58. Sensor 73,
Intake pressure sensor 7 for detecting the suction pressure in the suction port 53
4, a water temperature sensor 75 for detecting the cooling water temperature THW of the diesel engine 2, the crankshaft 4 of the diesel engine 2
Crank angle sensor 7 for detecting the rotation reference position of 0, for example, the rotation position of the crankshaft 40 with respect to the top dead center of the specific cylinder.
6. A vehicle speed sensor 77 for detecting the vehicle speed (vehicle speed) by turning on / off the reed switch 77b with a magnet 77a provided on the axle is provided.

In addition to the various sensors, an air conditioner switch 65 for detecting the operating condition of the air conditioner (air conditioner), a neutral switch 66 indicating that the range position of the automatic transmission (torque converter) is neutral,
An idle up switch 67 that is turned on or off when changing from the normal idle state to the idle up state or from the idle up state to the normal idle state is provided. In this embodiment, the air conditioner switch 65, the neutral switch 66 and the water temperature sensor 75 constitute an operating state detecting means, and the idle up switch 67 constitutes a mode change detecting means.

Each of the sensors 3 described above is provided in the ECU 71.
5, 72 to 77 and the switches 65 to 67 are respectively connected. Then, the ECU 71 uses the sensors 35, 7
2 to 77 and the signals output from the switches 65 to 67, the electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, and the VSVs 56, 6
1, 62 and the like are preferably controlled.

Next, the configuration of the above-mentioned ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 is a read-only memory (ROM) that stores in advance a central processing unit (CPU) 79 constituting a target rotation speed setting means, a setting rotation speed changing means, a rotation speed control means and an initial value setting means, a predetermined control program, a map and the like. ) 80, CP
A random access memory (RAM) 81 for temporarily storing the operation result of U79, a backup RAM 82 for storing previously stored data, etc., and a logical operation in which these units are connected to an input port 83, an output port 84, etc. by a bus 85. It is configured as a circuit.

The intake temperature sensor 7 is connected to the input port 83.
2, the accelerator opening sensor 73, the intake pressure sensor 74, and the water temperature sensor 75 are connected via the buffers 86, 87, 88, 89, the multiplexer 93, and the A / D converter 94. Further, the air conditioner switch 65, the neutral switch 66 and the idle up switch 67 are connected to the input port 83 via buffers 90, 91 and 92. Similarly, the rotation speed sensor 35, the crank angle sensor 76, and the vehicle speed sensor 77 are connected to the input port 83 via a waveform shaping circuit 95. Then, the CPU 79 reads the detection signals of the sensors 35, 72 to 77, the switches 65 to 67, etc., which are input via the input port 83, as input values. In addition, the output port 84 has respective drive circuits 96, 97, 98, 99, 100,
Via the electromagnetic spill valve 23, the timing control valve 33, the glow plug 46 and the VSV 56, 6
1, 62 and the like are connected.

Then, the CPU 79 controls the sensors 35 and 72.
~ 77 and the input values read from the switches 65 to 67, the electromagnetic spill valve 23, the timing control valve 33, the glow plug 46 and the VSV 56, 61 ,.
62 and the like are preferably controlled.

Next, the operation and effect of this embodiment configured as described above will be described. The flowchart of FIG. 5 shows a routine for idle rotation control, out of various processes executed by the CPU 79, which is executed by a regular interrupt every predetermined time.

In this flow chart, a flag FIUP for determining the change with time of two idle states, which are a normal idle state and an idle up state, is set. That is, when the idle-up control request signal for shifting from the normal idle state to the idle-up state is in the “off” to “off” state, that is, when the normal idle state is maintained, the flag FIUP is set. It is set to "1". Further, when the idle-up control request signal changes from "off" to "on" in order to shift from the normal idle state to the idle-up state, the flag FIUP is set to "2".
To maintain the idle-up state, the flag FIUP is set to "3" when the idle-up control request signal is in the "on" state from the "on" state. Further, in order to return from the idle-up state to the normal idle state, when the idle-up control request signal changes from "on" to "off" state, the flag FIUP is set to "0". There is.

When the processing shifts to the routine of FIG. 5, CP
First, in step 101, the U 79 determines whether or not the flag FIUP is “2”, and in step 102, the flag FIU.
It is determined whether P is "3" and the flag F is determined in step 103.
It is determined whether IUP is "0". These steps 1
When all the judgments of 01 to 103 are “NO”, C
The PU 79 determines that the flag FIUP is "1" and the normal idle state is maintained.

Then, the CPU 79 performs control for matching the actual rotation speed of the diesel engine 2 with the target rotation speed NF during normal idle. That is, first, at step 104, the target rotational speed NF at the time of normal idle (for example, 80
0 rpm) is calculated. The target rotation speed NF is, for example, the cooling water temperature THW of the diesel engine 2 detected by the water temperature sensor 75, the range of the torque converter set by the neutral switch 66 (D range or N range), and the state of the air conditioner switch 65 (on or off). ). When the target rotation speed NF is calculated,
The CPU 79 proceeds to step 105 and sets the addition term KIUP to the expected control amount NFP at idle-up described later to "0".

Subsequently, the CPU 79 proceeds to step 106 to calculate the expected control amount NFP at the time of normal idle due to the load change of the neutral switch 66, the air conditioner switch 65 and the like. Then, the integral control amount NFI is calculated based on the deviation ΔNF (= NF-NEQB) between the target rotation speed NF at the time of normal idle calculated in step 104 and the actual rotation speed NEQB detected by the rotation speed sensor 35.
To calculate. That is, the correction integration amount ΔNFI corresponding to the deviation ΔNF is obtained, and this is added and integrated (ΣΔNFI) to obtain the integration control amount NFI.

When the expected control amount NFP and the integral control amount NFI at the time of normal idle are calculated, the CPU 79 determines in step 10
7, the expected control amount NFP in step 106 described above.
Is added to the addition term KIUP to obtain the final expected controlled variable NFP. In this step 107, since the addition term KIUP in step 105 is "0", the normal idle expected control amount NFP obtained in step 106 is directly used as the final expected control amount NFP.

Next, the CPU 79 proceeds to step 108 and executes a process for matching the actual rotation speed NEQB with the target rotation speed NF at the time of normal idle. CPU79
First, the corrected rotational speed NEISC during normal idle is calculated based on the following equation (1).

NEISC = NEQB- (NFP + NFI) (1) After calculating the corrected rotational speed NEISC, the CPU 79 calculates the fuel injection amount based on the accelerator opening ACC by the accelerator opening sensor 73 and the corrected rotational speed NEISC. Is obtained by a map search or a calculation formula. As a result, the apparent governor pattern is translated by NFP + NFI in the rotational speed axis direction. Next, an injection amount command value corresponding to the above injection amount is obtained, and this is output to the drive circuit 96 of the electromagnetic spill valve 23, and this routine ends. As a result, the fuel injection amount is adjusted, and the actual rotation speed NEQB of the diesel engine 2 is controlled to become the target rotation speed NF during normal idle.

In step 101, the flag FIU is set.
When P becomes "2", the CPU 79 determines that the idle-up switch 67 is turned on and the idle-up operation condition is satisfied (timing of t ₀ in FIG. 6), and the normal idle mode up to that point is changed to the idle-up mode. Transition. After this idle up mode transition, CP
The U79 proceeds to step 109 to temporarily store the final integrated control amount NFI in the normal idle mode as NFIBASE.

Next, the CPU 79 sets the flag FIUP to "3" in step 110 to store that the idle-up mode has been entered, and in step 111,
The count value TIUP of the counter for measuring the elapsed time after the idle-up mode is set is set to "0". Then, the routine proceeds to step 112, where the target rotation speed at the time of idling up (for example, 1200 rpm) is calculated in the same manner as step 104, and this is set as the target rotation speed NF. Subsequently, the CPU 79 proceeds to step 113
Then, the expected control amount in the idle-up mode is calculated, and the addition term KIUP to be added to the expected control amount NFP in the normal idle mode in order to obtain this expected control amount is calculated. Then, when this addition term KIUP is calculated,
The CPU 79 performs the processing of steps 106 to 108 and ends this routine. In step 107, the final control amount NFP is obtained by adding the addition term KIUP in step 113 to the control amount NFP in the normal idle mode.

Steps 109-113 and 106-1
When the process of 08 is executed, the flag FIUP is set to "3" in step 110, so in the next process, the CPU 79 shifts to step 114 after making the determinations of steps 101 and 102. CPU in step 114
Reference numeral 79 increments the count value TIUP of the counter by "1".

Next, in step 115, the CPU 79 determines whether or not a predetermined time (for example, 1 second) has elapsed from the transition from the normal idle mode to the idle up mode, and a predetermined time corresponding to the predetermined time. The value T ₀ is compared with the count value TIUP of the counter. Immediately after changing to idle up mode, the count value TIU
P is less than or equal to the predetermined value T ₀ . As described above, the count value T
If the IUP is equal to or less than the predetermined value T ₀ , the CPU 79 performs the above-mentioned steps 112, 113, 106 to 108 and ends this routine.

When the count value TIUP becomes larger than the predetermined value T ₀ (TIUP> T ₀ ) in the step 115 by the subsequent processing, the CPU 79 shifts to the idle up mode for a predetermined time (in this case, 1 second). ) Has elapsed, and it is determined that the actual rotation speed NEQB has stabilized (timing of t ₁ in FIG. 6). Then, the CPU 79 proceeds to step 116, and the integral control amount N after the predetermined time has elapsed.
Store the FI as NFIU1. Then, the processing of steps 112, 113, and 106 to 108 described above is performed, and this routine is ended. As a result, the fuel injection amount is adjusted, and the actual rotation speed NEQB of the diesel engine 2 is controlled to be the target rotation speed NF during idle-up.

By the way, when the flag FIUP becomes "0" at step 103, CPU 79 determines that the idle-up switch 67 is turned off has been idle up stop condition is satisfied (timing t ₂ in FIG. 6), it Return from normal idle mode to normal idle mode. After returning to the normal idle mode, the CPU 79 proceeds to step 117, and first stabilizes the integrated control amount NFIU1 after changing to the idle up mode (see step 116) and the last integrated control amount NFI in the idle up mode. And the ratio KNFI is calculated. This ratio KNFI indicates the change rate of the increment of the integrated control amount during the idle up mode.
For example, when the fuel temperature rises due to the change in operating conditions over time, the integral control amount NFI increases to compensate for the decrease in the fuel injection amount due to the rise in the fuel temperature, so the ratio KNFI is "1." More than that.

After the calculation of the ratio KNFI, the CPU 79 performs processing for guarding the lower limit value of this ratio KNFI to "1.0" in steps 118 and 119. That is, in step 118, the ratio KNFI is "1.0".
If it is less than "1.0", the ratio KNFI is set to "1.0" in step 119. In step 118, the ratio KNFI is "1.0"
If it is above, the CPU 79 proceeds to step 120 and performs a process of correcting the ratio KNFI to KNFI × K ₀ . K ₀ is a constant larger than 1.0, and the amount of change in NFI that normally occurs at idle speed and the NFI that occurs at idle up speed for the same temperature rise.
Corresponding to the ratio of the change amount of, and is predetermined experimentally.

Then, the CPU 79 proceeds to step 121, where NFIBASE (see step 109) which is the final integrated control amount NFI in the normal idle mode when the normal idle mode is shifted to the idle up mode is set to the above ratio. Multiply by KNFI. Therefore, the value obtained as described above is the same as the integral control amount NFIBASE or a value larger than the integral control amount NFIBASE. Then, the CPU 79 sets this value as the initial value of the integral control amount NFI when returning from the idle-up mode to the normal idle mode.

The CPU 79 uses the initial value of the integral control amount NFI obtained in step 121, and executes step 1 described above.
The processing of 04 to 108 is performed, and this routine is ended.
As a result, the fuel injection amount is adjusted, and the actual rotation speed NEQB of the diesel engine 2 is controlled to become the target rotation speed NF during normal idle.

As described above, in this embodiment, when returning from the idle-up mode to the normal idle mode, the integrated control amount NFIBASE at the time of normal idle immediately before the start of idle-up is changed to the integrated control amount NF at the time of idle-up.
Correction (KNFI) based on the change rate (KNFI) of the increment of I
NFI × NFIBASE), and the value is used as an initial value of the integrated control amount NFI at the time of normal idle this time (steps 117 to 120). Then, the change in the integrated control amount NFI at the time of idling up represents the rise in the fuel temperature at the idling up, and this is reflected in the calculation of the integrated control amount NFI at the time of the normal idling this time. Therefore, the integrated control amount NFI corresponding to the fuel temperature and the target rotational speed NF at the current normal idle time is set.
Then, the idle rotation control is performed.

Therefore, when the fuel temperature rises during idle-up and the normal idle mode is restored from this state, the decrease in the fuel injection amount due to the rise in fuel temperature becomes larger than that during idle-up. Regardless, the decrease can be compensated by the integral control amount corrected as described above. Therefore, in the present embodiment, unlike the prior art, when returning from the idle-up mode to the normal idle mode, it is possible to prevent the actual rotation speed NEQB from falling too much below the target rotation speed NF during normal idle.

[0057]

As described above in detail, according to the present invention, at the time of returning from the idle-up mode to the normal idle mode, the integral control amount at the time of the normal idle immediately before the start of the idle-up is set at the idle-up time. Since it was corrected based on the change amount of the integrated control amount in the rotation speed control means of the above, and the initial value of the integrated control amount at the time of the normal idle this time was set, when returning from the idle up mode to the normal idle mode. In addition, even if the fuel temperature rises due to changes in the operating conditions over time, it is possible to prevent the actual rotation speed from falling below the target rotation speed during normal idle.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention.

FIG. 2 is a schematic configuration diagram showing an idle rotation control device for a diesel engine in one embodiment embodying the present invention.

FIG. 3 is a sectional view showing a distributed fuel injection pump in one embodiment.

FIG. 4 is a block diagram showing a configuration of an ECU in one embodiment.

FIG. 5 is a flowchart for explaining idle rotation control executed by a CPU in the embodiment.

FIG. 6 is a diagram showing a relationship between time and rotation speed in one example.

[Explanation of symbols]

2 ... Diesel engine, 23 ... Electromagnetic spill valve as rotation speed adjusting means, 35 ... Rotation speed sensor as rotation speed detecting means, 65 ... Air conditioner switch forming part of operation state detecting means, 66 ... Operating state detecting means , A neutral temperature switch 67 forming part of the mode change detecting means, a water temperature sensor forming part of the operating state detecting means 75, a target rotation speed setting means, a setting rotation speed changing means , CPU constituting rotation speed control means and initial value setting means

Claims (1)

Claim: What is claimed is: 1. A rotation speed adjusting means for adjusting the rotation speed of the diesel engine by adjusting the fuel injection amount to the diesel engine, and a rotation speed for detecting the rotation speed of the diesel engine. Detecting means, operating state detecting means for detecting the operating state of the diesel engine, target rotational speed setting means for setting a target rotational speed according to the operating state of the diesel engine by the operating state detecting means, and the diesel engine When the mode change detection means detects a transition from the normal idle mode to the idle up mode or a return from the idle up mode to the normal idle mode, and when the mode change is detected by the mode change detection means, the target rotation speed setting means Forcibly raises or lowers the target rotation speed by a specified amount The set rotation speed changing means and the rotation speed detecting means rotate the rotation speed by feedback control using an integral control amount so that the rotation speed becomes the target rotation speed raised or lowered by the setting rotation speed changing means. A rotation speed control means for controlling the speed adjusting means, and a return speed from the idle-up mode to the normal idle mode. An idle rotation control device for a diesel engine, comprising: an initial value setting unit that corrects the integrated control amount based on the above condition and sets the initial value of the integrated control amount at the time of normal idling this time.