JPS63105231A - Method of controlling supercharging change-over for compound supercharged internal combustion engine - Google Patents

Abstract

PURPOSE:To absorb a torque fluctuation due to change-over by causing the ignition timing to be advanced or delayed in advance in the neighborhood of a changing-over time of a supercharging means. CONSTITUTION:The output of a crank angle sensor 40 is subjected to waveform shaping in a waveform shaping circuit 50 before it is inputted by means of an input interface circuit 52 into a microcomputer 54. In addition, the output of both a negative pressure sensor 42 and a supercharged pressure sensor 44 is also inputted into the microcomputer 54 by means of an A/D converter 56, and a CPU 58 computes control values by means of an RAM 62 in accordance with a control program stored in an ROM 60 according to those input signals, and outputs both clutch ON-OFF control signals by means of an output interface circuit 64 to an electromagnetic clutch 36 and ignition timing signals to an igniter 46. And further, for example, in the case of a changing-over from a supercharger to a turbosupercharger, the ignition timing is gradually delayed in advance in anticipation of a delay in the engine, and then, it is restored in the direction of the angle of advance.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a supercharging switching control method for a compound supercharged internal combustion engine, and more specifically, the present invention relates to a supercharging switching control method for a multi-supercharged internal combustion engine, and more specifically, the present invention relates to a supercharging switching control method for a compound supercharged internal combustion engine, and more specifically, the present invention relates to a supercharging switching control method for a compound supercharged internal combustion engine, and more specifically, the present invention relates to a supercharging switching control method for a compound supercharged internal combustion engine, and more specifically, the present invention relates to a supercharging switching control method for a compound supercharged internal combustion engine, and more specifically, the present invention relates to a supercharging switching control method for a compound supercharged internal combustion engine, and more specifically, the present invention relates to a supercharging switching control method for a hybrid supercharged internal combustion engine, and more specifically, The present invention relates to a method for smoothly controlling switching of supercharging means in an internal combustion engine.

(Prior Art) In recent years, exhaust turbine-driven superchargers (hereinafter referred to as "turbochargers") have been increasingly used to improve engine output. In this region, there is a time lag problem in which sufficient torque cannot be obtained because the exhaust gas pressure is low. To solve this problem, make the turbine smaller and lighter.
Various methods have been taken, such as installing two turbines to create a twin turbo, but among these methods is a method that uses a turbocharger in combination with a mechanically driven supercharger (hereinafter referred to as a "supercharger"). Examples thereof include the technique described in Japanese Unexamined Utility Model Publication No. 56-127334 and the technique described in Japanese Unexamined Patent Publication No. 60-26125.

As described above, in the case of a composite supercharged internal combustion engine that has both a turbocharger and a supercharger, the supercharger will mainly supercharge in the low speed range, and only the turbocharger will supercharge in the high speed range. Therefore, flat and uniform supercharging pressure can be obtained throughout the entire rotation range.

(Problems to be Solved by the Invention) Incidentally, in the case of such a compound supercharged internal combustion engine, it is necessary to connect or disconnect the supercharger and the engine driving force via an electromagnetic clutch in a predetermined rotation range. In that case, when switching from a supercharger to a turbocharger alone, when the supercharger is disconnected, the engine load suddenly decreases, resulting in a sudden increase in torque, and in the opposite case, the engine load suddenly decreases, causing a sudden decrease in torque. In any case, every time the supercharger is switched, a sudden torque fluctuation occurs, causing a disadvantage that drivability is deteriorated.

If such inconvenience were to be solved, it would be necessary to provide a complicated and expensive control device that keeps the electromagnetic clutch in a half-clutch state for a predetermined period of time during switching.

Therefore, an object of the present invention is to provide a control method that can effectively prevent torque fluctuations during switching using a simple method (without installing such an expensive and complicated control device), and which can also be used with simple ON-OFF control. The objective is to provide a control method that is easy to use.

(Means for Solving the Problems) In order to achieve the above object, the present invention has a plurality of supercharging means and a method for sequentially switching the plurality of supercharging means depending on one engine operating parameter. In the internal combustion engine according to the present invention, the ignition timing is advanced or retarded in advance near the time of switching when the sequential switching is performed.

(Function) When switching between the supercharger and turbocharger, the ignition timing is advanced or retarded to increase or decrease the torque from near the switching point in anticipation of engine delays, so the torque fluctuations caused by switching can be reduced. Therefore, deterioration of drivability can be prevented.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

For convenience, an apparatus for implementing the present invention will first be described with reference to FIGS. 1 and 2. FIG.

In FIG. 1, reference numeral 10 indicates a combustion chamber of an internal combustion engine, and an exhaust turbine 14 of a turbocharger is installed at an appropriate location in its exhaust passage 12, and its rotational force is transmitted to an intake passage 18 via a shaft 16. The installed compressor 20 is driven to compress air introduced through an air cleaner (not shown) and forcefully send it into the combustion chamber 10. A second intake passage 22 is further provided parallel to the intake passage 18, and the second intake passage 2
A roots-type compressor 24 of a supercharger is disposed at an appropriate location of 2. The second intake passage 22 branches from the first intake passage 18 on its upstream side, and joins again on its downstream side via a common intake passage 26 as shown. The Roots type compressor 24 receives the rotational force of a crankshaft (not shown) connected to the piston 28 via pulleys 30, 32 and a belt 34, and is driven by these. Therefore, the pulley is 30.3
The pulley ratio of No. 2 is controlled according to increases and decreases in engine speed, and the boost pressure of the Roots type compressor 24 is kept substantially constant. Reference numeral 36 designates an electromagnetic clutch, which is configured to transmit or not transmit the rotation of the crankshaft to the Roots type compressor 24 by turning the clutch ON10FF.
0FF is controlled by control unit 3.

Furthermore, a crank angle sensor 40 for detecting the crank angle position of the piston 28 is provided at an appropriate location such as in a distributor (not shown), and a cylinder TDC position signal,
It creates a unit angle signal, etc. and sends it to the control unit 38, as well as the intake manifold (not shown).
A negative pressure sensor 42 for detecting suction negative pressure and a supercharging pressure sensor 44 for detecting supercharging pressure are provided at appropriate locations, and the outputs of both sensors are also sent to the control unit 38.

On the other hand, the control unit 38 sends a 0N10FF control signal to the electromagnetic clutch 36, and also creates an ignition timing signal and sends it to the igniter 46, and the igniter 46 controls the spark plug 48 based on the control signal.
The air-fuel mixture in the combustion chamber IO is ignited through the combustion chamber IO. In addition, code 4
9 is a first intake path 18. and a check valve provided in the second intake passage 22.

FIG. 2 shows the details of the control unit 38. To explain according to the figure, the output of the crank angle sensor 40 is waveform-shaped by the waveform shaping circuit 5o, and then sent to the microcontroller via the input interface circuit 52. - input into computer 54; Further, the outputs of the negative pressure sensor 42 and the boost pressure sensor 44 are also input into the microcomputer 54 via the A/D converter 56, and the CP
Based on these input signals, U58 calculates a control value via RAM 62 according to a control program stored in ROM 60, and outputs a clutch 0N10FF control signal to electromagnetic clutch 36 via output interface circuit 64, and outputs a clutch 0N10FF control signal to electromagnetic clutch 36 via output interface circuit 64. An ignition timing signal is output to 46.

Next, an embodiment of the supercharging switching control method according to the present invention will be described with reference to the flow chart in FIG. Before explaining each step, the present control method will be outlined with reference to FIG. In the same figure (A), the engine speed Ne increases and the engine speed increases.
A case is shown in which the charger is switched to a turbo charger, and FIG. 2B shows a case in which the engine speed Ne decreases and the turbo charger is switched to a supercharger. In either case, the electromagnetic clutch is turned 0N10FF at the rotation speed NeO, but when switching to the turbocharger shown in Figure (A), the ignition timing is gradually adjusted from the rotation speed Ne in anticipation of engine delay. retarded,
From the moment the clutch OFF rotation speed NeO is exceeded, the rotation speed N
The angle is returned to the advance direction while reaching e2. That is, the torque is reduced by retarding the torque to absorb torque fluctuations caused by a sudden load reduction due to the supercharger being turned off.

The same is true in the case of (B) in the same figure; when switching to the supercharger, the turbocharger is also operated in parallel), advance the ONL in advance, and then retard the engine. This is to absorb torque fluctuations.

Note that this switching correction value for advancing or retarding ignition timing is θ.
It is called C.

In addition, in the above, the rotational speeds Nel and NeO+Ne2 are set to values close to each other, and are kept to the minimum level necessary to absorb the torque fluctuations caused by the clutch 0N10FF, so that unnecessary torque fluctuations do not occur. To explain the premise by returning to FIG. 3, first, in step 70, it is determined whether the current engine speed Ne is increasing or not, that is, whether it is in FIG. 4 (A) or (B). this is,
From the unit angle signal of the crank angle sensor 40, the rotational speed Ne
After calculating, the amount of change is calculated and the judgment is made.

If the rotational speed Ne is increasing (FIG. 4(A)), then in step 72 it is determined whether the rotational speed Ne is less than 1,
If it is less than the predetermined value ΔNeref, it is determined whether the rotational speed change rate ΔNe shown in FIG. 4 is within a predetermined value ΔNeref or not in step 76). This decision was made to avoid excessive torque fluctuations if the supercharger was switched when the rotational speed suddenly increased or decreased.

If the rate of change ΔNe is within the predetermined range, then step 78
, the ignition timing switching correction value θC (initial value ゛0
) is retarded by n degrees (in this flow chart, subtraction retards the retard angle, and addition retards the advance angle). The value of this n゛ is
It is selected as appropriate, for example, once. It is more preferable to gradually change the value of n so that the advance/retard angle characteristic becomes flat near the switching point, as shown by curves ``A'' and ``A'' in FIG.

Subsequently, each time an ignition command is issued in the ignition timing calculation described later, the ignition speed is retarded by n degrees until the switching speed Neo is reached (Step 80.82), and when the speed is reached, the electromagnetic clutch 36 is set to 0FFL, and the driving of the Roots type compressor 24 is stopped. (step 84).

As described above, in the present control method, the control of the electromagnetic clutch itself is sufficient to be simply ON10FF control, and at the same time, in step 86, the switching correction value θC begins to be returned to the advance direction, and the ignition command is continued until the rotation speed Ne2 is reached. It is corrected n times each time (steps 88 and 90). Note that if there is insufficient return or too much return, correct it as appropriate (step 92.
94).

Further, if the rotational speed Ne exceeds Nel and is less than Ne0 in the judgment at step 72, the rate of change ΔNe is judged and the retardation is started (steps 96, 76.78).
If it exceeds o and is less than Ne2, the electromagnetic clutch 36 is still at O.
If it is not turned off, turn it off and start the return correction,
If Ne2 or more, there is no need for OFF control, so the process returns (step 98°84.86).

Further, if it is determined in step 70 that the current rotational speed Ne is decreasing (FIG. 4(B)), it is determined whether or not the rotational speed Ne exceeds Ne2, and if it exceeds Ne2.
The rate of change ΔNe is determined after reaching NeO, and if it is within a predetermined range, the ignition is advanced by n degrees each time the ignition command is issued in anticipation of engine delay, and when NeO is reached, the electromagnetic clutch 36 is turned off.
Start driving the super charger at NL (step 100-1) 2). At the same time, N times each time the ignition command is issued.
The angle is returned to the retarded direction until reaching e1, and if there is any remaining, it is corrected (Step 1) 4-122). Also, the current rotation speed N
If e is below Ne2 and does not reach NeO, the rate of change is determined and the angle is advanced (steps 124, 104).
, 106) , If it is below NeO, it is above the surface Nel and if the clutch is not ON, then ONL, ,N
If it is less than e1, return (step 126, 1)
2).

FIG. 5 shows an ignition timing calculation flow chart. In the aforementioned control unit 38, the clutch control flow shown in FIG. It is determined. That is, first in step 200, the basic ignition timing θb is calculated. This is done by searching the basic control value map stored in the ROM 60 based on the rotational speed Ne calculated by the crank angle sensor 40 and the negative pressure value output from the negative pressure sensor 42 by the CPO 58 .

Next, in step 202, temperature correction, knock correction, etc. are performed from the outputs of the water temperature sensor, knock sensor (both not shown), etc., and a general correction value θk is calculated, and step 204
Then, the ignition timing θig is calculated from them.

Subsequently, in step 206, it is determined whether or not there is a switching correction value θC, and if so, it is appropriately corrected in the advance or retard direction in step 208, and in the final step 210, an ignition command is sent to the igniter 46.

As described above, in the flowchart of FIG. 3, this embodiment shows an example in which control is performed based on the engine speed Ne and the engine speed change rate ΔNe, but the invention is not limited to this. It may be based on pressure, engine speed, boost pressure, etc.

Further, when switching, hysteresis is provided by setting the advance or retard starting point to Nel or Ne2 depending on the direction of increase/decrease in the rotational speed, but the switching rotational speed NeO may also be changed depending on the direction of increase/decrease.

Figure 6 schematically shows the supercharging pressure obtained by this control method. In the low rotation range, sufficient supercharging pressure is obtained mainly by the supercharger (supplementally the turbo charger), and in the high rotation range, The supercharging pressure is obtained only from the turbo charger, which enables flat and uniform supercharging throughout the entire rotation range, and further reduces the switching speed Ne.
Even when switching at 0, drivability is not impaired.

(Effects of the Invention) The present invention is configured to advance or retard the ignition timing in advance near the time of switching when a plurality of supercharging means are sequentially switched, so that deterioration of drivability due to torque fluctuation at the time of switching can be prevented. This has the advantage of being able to obtain uniform supercharging pressure over the entire rotation range while preventing this. In addition, it is a simple method that requires only 0N10FF control, and has the advantage that it is cheaper than the case where a complicated and expensive control device is provided, and there is no possibility of failure.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of a device used to realize the present invention, FIG. 2 is an explanatory block diagram of the control unit, FIG. 3 is a flow chart showing an embodiment of the present invention, and FIG. The figure is an explanatory diagram showing the control method of the flow chart, Figure 5 is a flow chart showing the ignition timing calculation performed in parallel with the flow chart in Figure 3, and Figure 6 is the supercharging obtained in this control. It is an explanatory view showing pressure.

Claims (4)

[Claims] (1) In an internal combustion engine having a plurality of supercharging means and in which the plurality of supercharging means are sequentially switched depending on at least one engine operating parameter, the ignition timing is advanced in advance near the switching point when the sequential switching is performed. 1. A supercharging switching control method for a compound supercharged internal combustion engine, characterized by adjusting the timing or retarding the timing. (2) Among the plurality of supercharging means, one is a mechanically driven supercharging means that supercharges using power from the engine output shaft, and the other is an exhaust turbine driven supercharging means. A supercharging switching control method for a compound supercharged internal combustion engine according to scope 1. (3) The engine operating parameter is one or a combination of engine speed, engine speed and suction negative pressure, engine speed and boost pressure, or engine speed change rate. A supercharging switching control method for a composite supercharging internal combustion engine according to claim 1. (4) The supercharging switching control method for a composite supercharging internal combustion engine according to claim 1, characterized in that the engine operating parameter has hysteresis.