JPH0768911B2 - Supercharging switching control method for combined supercharging internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharge switching control method for a combined supercharged internal combustion engine, and more specifically, an exhaust turbine driven supercharger and a mechanical driven supercharger. The present invention relates to a method for smoothly controlling the switching of the supercharging means in the internal combustion engine.

(Prior Art) In recent years, an exhaust turbine driven supercharger (hereinafter referred to as a "turbocharger") has been actively used in order to improve engine output. In the case of this turbocharger, as is well known, a low rotation speed is provided. In the region, there is a problem of time lag that sufficient torque cannot be obtained because the exhaust gas pressure is low. In order to solve it, reduce the size and weight of the turbine,
Various means have been taken, such as installing two turbines to make a twin turbo. Among them, a method of combining a turbocharger with a mechanical drive supercharger (hereinafter referred to as "supercharger") is used. The technology described in Japanese Utility Model Laid-Open No. 56-127334 or JP-A-60-
The technique described in Japanese Patent No. 26125 can be mentioned.

As described above, in the case of the combined supercharged internal combustion engine having both the turbocharger and the supercharger, the supercharger is mainly supercharged in the low speed region and only the turbocharger is supercharged in the high speed region. Therefore, a flat and uniform boost pressure can be obtained over the entire rotation region.

(Problems to be Solved by the Invention) By the way, in the case of such a composite 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 region. In that case, when switching from the supercharger to the turbocharger alone, when the supercharger is disconnected, the engine load sharply decreases and the torque sharply increases, and in the opposite case, the engine load sharply increases and the torque sharply decreases. In any case, a sudden torque fluctuation occurs every time the supercharger is switched, which causes a problem of deteriorating drivability. In order to eliminate such inconvenience, it is necessary to provide a complicated and expensive control device such that the electromagnetic clutch is kept in the clutch state for a predetermined time and half during the switching.

Therefore, an object of the present invention is to provide a control method capable of effectively preventing torque fluctuation at the time of switching without providing such an expensive and complicated control device, and further, simply ON / OFF control is required. It is to provide a control method.

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

(Operation) When switching between the supercharger and turbocharger, the ignition timing is advanced or retarded to increase or decrease the torque in advance from near the switching point in anticipation of the engine delay. It can be absorbed, and thus deterioration of drivability can be prevented.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

For convenience, the apparatus for implementing the present invention will be described first with reference to FIGS.

In FIG. 1, reference numeral 10 indicates a combustion chamber of an internal combustion engine, an exhaust turbine 14 of a turbocharger is installed at an appropriate portion of the exhaust passage 12, and its rotational force is transmitted via an axis 16 to an intake passage 18
The compressor 20 installed in the combustion chamber to compress the air introduced through an air cleaner (not shown)
Pump within 10. A second intake passage 22 is further provided in parallel with the intake passage 18, and a roots type compressor 24 of a supercharger is arranged at an appropriate portion of the second intake passage 22. The second intake passage 22 branches off from the first intake passage 18 on the upstream side, and joins again via the common intake passage 26 on the downstream side as shown in the drawing. The roots compressor 24 receives the rotational force of a crank shaft (not shown) connected to the piston 28 via the pulleys 30 and 32 and the belt 34, and is driven by this. Thus, the pulley ratio of the pulleys 30 and 32 is controlled in accordance with the increase / decrease in the engine speed, and the supercharging pressure of the roots type compressor 24 is kept substantially constant. Reference numeral 36 denotes an electromagnetic clutch, which is configured to transmit or not transmit the rotation of the crankshaft to the roots compressor 24 by turning on / off the clutch. The electromagnetic clutch 36 is turned on / off. Is controlled by the control unit 38.

Further, a crank angle sensor 40 for detecting the crank angle position of the piston 28 is provided at an appropriate place in a distributor (not shown) or the like, and a cylinder TDC position signal, a unit angle signal, etc. are created to form a control unit. A negative pressure sensor 42 for detecting the suction negative pressure and a supercharging pressure sensor 44 for detecting the supercharging pressure are provided at appropriate points of the intake manifold (not shown). It is sent to the control unit 38. On the other hand, the control unit 38 sends an ON / OFF control signal to the electromagnetic clutch 36, creates an ignition timing signal and sends it to the igniter 46, and the igniter 46 sends an ignition plug based on the control signal. The mixture in the combustion chamber 10 is ignited via 48. The reference numeral 49 designates the first intake passage 18 and the second intake passage 22.
The check valve provided in FIG.

FIG. 2 shows the details of the control unit 38. The output of the crank angle sensor 40 is waveform-shaped by the waveform shaping circuit 50, and then the microcomputer via the input interface circuit 52. Entered within 54. Further, the negative pressure sensor 42 and the boost pressure sensor 44
The output of the CPU is also input into the microcomputer 54 via the A / D converter 56, and the CPU 58 of the CPU outputs the R according to the control program stored in the ROM 60 based on those input signals.
Output interface circuit that calculates control value via AM62
A clutch ON / OFF control signal is output to the electromagnetic clutch 36 and an ignition timing signal is output to the igniter 46 via 64.

Next, an embodiment of the supercharging switching control method according to the present invention will be described with reference to the flow chart of FIG. Before explaining each step, the present control method will be outlined with reference to FIG. The figure (A) shows the case where the engine speed Ne increases and the supercharger is switched to the turbocharger, and the figure (B) the engine speed Ne decreases and the turbocharger is switched to the supercharger. Indicate the case. In either case, the electromagnetic clutch is turned on / off at the rotation speed Ne0.
When switching to the charger, the ignition timing is gradually retarded in advance from the rotational speed Ne1 in anticipation of engine delay, and the clutch is turned off.
From the time when the rotation speed exceeds Ne0 to the rotation speed Ne2, it is returned in the advance direction. That is, the torque is retarded and the torque is reduced to absorb the torque fluctuation due to the sudden load reduction due to the supercharger OFF. The same applies to the case of FIG. 7B, when switching to the supercharger (more precisely, the turbocharger is also operated in parallel), advance it in advance and turn it on, and then in the retard direction. The torque fluctuation is absorbed by returning to. The ignition timing switching correction value for advancing or retarding the ignition timing is referred to as “θc”. or,
In the above description, the rotational speeds Ne1, Ne0, Ne2 are values close to each other, and are kept to the minimum necessary to absorb the torque fluctuation caused by the clutch ON / OFF to prevent unnecessary torque fluctuation.

Returning to FIG. 3 on the premise of the above, first, at step 70, whether or not the engine speed Ne at the present time is increasing,
That is, it is determined whether it is FIG. 4 (A) or (B). This is determined by calculating the rotational speed Ne from the unit angle signal of the crank sensor 40 and then calculating the amount of change thereof.

If the rotation speed Ne is increasing (FIG. 4 (A)), it is then determined in step 72 whether or not the rotation speed Ne1 is less than that. If it is less than that, it is confirmed that the rotation speed Ne1 is reached (step 74). Then, at step 76, the rotational speed change rate Δ shown in FIG.
It is determined whether Ne is within a predetermined value ΔNeref. If the supercharger is switched when the rotational speed is suddenly increased or decreased, the torque fluctuation will be too large, and this is a judgment to avoid it. If the rate of change ΔNe is within a predetermined range, then in step 78, the ignition timing switching correction value θc (initial value “0”) is retarded by n degrees (in this flow chart, subtraction is retarded and addition is retarded). Means advance angle). The value of "n" is appropriately selected and is set to, for example, once. It is more preferable to gradually change the value of n so that the advance / retard characteristic becomes flat near the switching point, as indicated by the curve "a" or "b" in FIG.

Subsequently, the ignition speed is retarded by n degrees each time an ignition command is issued in the ignition timing calculation described later (steps 80, 82) until the switching speed Ne0 is reached, and when the ignition speed is reached, the electromagnetic clutch 36 is turned off and the roots compressor 24 is driven. Stop (step 8
Four). As described above, in the present control method, the control of the electromagnetic clutch itself may be a simple ON / OFF control.

At the same time, in step 86, the switching correction value θc is started to return in the advance direction, and is corrected every n times until an engine speed Ne2 is reached (steps 88, 90). Incidentally, if there is insufficient return or excessive return, it is appropriately corrected (steps 92, 9).
Four).

Also, in the judgment of step 72, the rotation speed Ne exceeds Ne1 and N
If it is less than e0, the rate of change ΔNe is judged to start retarding (steps 96, 76, 78), and if it exceeds Ne0 and is less than Ne2, the electromagnetic clutch 36 is turned off if it has not been turned off yet, and correction is performed. Is started, and if Ne2 or more, OFF control is not necessary and the process returns (steps 98, 84, 86).

Further, when it is determined in step 70 that the current rotational speed Ne is decreasing (FIG. 4 (B)), the rotational speed Ne is
If Ne2 is exceeded, if it exceeds Ne2, the change rate ΔNe is judged by waiting for Ne2 to reach. If it is within a predetermined range, the ignition command is advanced by n degrees each time there is an ignition command in anticipation of engine delay, and Ne0 is set. When it arrives, the electromagnetic clutch 36 is turned on to start driving the supercharger (steps 100-112). At the same time, each time the ignition command is given, it is returned in the retard direction until reaching Ne1 every n degrees,
If there is a residue, it is corrected (steps 114-122). If the current rotational speed Ne is lower than Ne2, if the speed does not reach Ne0, the rate of change is judged and the angle is advanced (steps 124, 104,
106), if it is below Ne0, it is still above Ne1 and the clutch is turned on if it is not turned on, and if it is less than Ne1, it returns (steps 126 and 112).

FIG. 5 shows an ignition timing calculation flow chart. In the control unit 38, the clutch control flow shown in FIG. 3 is always performed, and this ignition timing calculation flow is performed in such a manner that it interrupts at the ignition calculation timing. At that time, the ignition timing is adjusted in consideration of the switching correction value θc. It is determined. That is, first, at step 200, the basic ignition timing θb
Is calculated. This is performed by searching the basic control value map stored in the ROM 60 based on the rotation speed Ne calculated by the CPU 58 from the crank angle sensor 40 and the negative pressure value output from the negative pressure sensor 42.

Next, in step 202, temperature correction, knock correction, etc. are performed from the outputs of the water temperature sensor, knock sensor (neither is shown), etc., the general correction value θk is calculated, and in step 204, the ignition timing θig is calculated. To do.

Next, in step 206, it is judged whether or not the switching correction value θc is present, and if there is a correction value θc, it is corrected in the advance or retard direction in step 208 as appropriate, and in the final step 210, an ignition command is sent to the igniter 46.

As described above, the present embodiment shows an example in which the engine speed Ne and the engine speed change rate ΔNe are used as a reference in the flow chart of FIG. 3, but the present invention is not limited to this.
The engine speed and the negative pressure, the engine speed and the supercharging pressure may be used as a reference. Also, when switching, the advancing or retarding starting point is set to Ne1 or Ne2 depending on the increasing / decreasing direction of the rotational speed to provide hysteresis, but the switching rotational speed Ne0 may be changed depending on the increasing / decreasing direction.

FIG. 6 schematically shows the supercharging pressure obtained by this control method. In the low rotation region, the supercharging pressure mainly by the supercharger (auxiliary turbocharger) is sufficiently obtained and in the high rotation region. The supercharging pressure is obtained only by the turbocharger, which enables flat and uniform supercharging throughout the entire rotation range.
The drivability is not impaired even when switching is performed in.

(Effect of the Invention) Since the present invention is configured such that the ignition timing is advanced or retarded in the vicinity of the switching time point when the plurality of supercharging means are sequentially switched, deterioration of drivability due to torque fluctuations at the time of switching is prevented. This has the advantage that a uniform boost pressure can be obtained over the entire rotation range while preventing it. Also, just
It is a simple method that requires only ON / OFF control, and has an advantage that it is less expensive and there is no room for failure as compared with the case where a complicated and expensive control device is provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an apparatus used for realizing the present invention, FIG. 2 is an explanatory block diagram of its control unit, FIG. 3 is a flow chart showing an embodiment of the present invention, and FIG. FIG. 6 is an explanatory view showing a control method of the flow chart, FIG. 5 is a flow chart showing an ignition timing calculation performed in parallel with the flow chart of FIG. 3, and FIG. 6 is a supercharging obtained in this control. It is explanatory drawing which shows pressure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Yamada 1-4-1 Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. (56) References JP-A-59-138748 (JP, A) Kaisho 62-195418 (JP, A)

Claims (4)

[Claims] 1. An internal combustion engine having a plurality of supercharging means for sequentially switching the plurality of supercharging means in accordance with at least one engine operating parameter, in advance of ignition timing in the vicinity of a switching time point when the sequential switching is performed. A method of controlling supercharging switching of a complex supercharging internal combustion engine, characterized in that the engine is advanced or retarded. 2. One of the plurality of supercharging means is a mechanical drive supercharging means for supercharging by power from an engine output shaft,
The supercharging switching control method for a combined supercharging internal combustion engine according to claim 1, wherein the other is an exhaust turbine driven supercharging means. 3. The engine operating parameter is an engine speed,
The composite according to claim 1, wherein one or a combination of engine speed and suction negative pressure, engine speed and supercharging pressure, or engine speed change rate. Supercharged switching control method for internal combustion engine. 4. The supercharging switching control method for a complex supercharged internal combustion engine according to claim 1, wherein the engine operating parameter has a hysteresis.