JPS6287617A - Compound supercharging device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent a drop in output at the time of transition from occurring, by making a mechanical supercharger operate only at a time when a suction air quantity is less than the specified value, and performing the transition from the mechanical supercharger to an exhaust turbosupercharger so smoothly. CONSTITUTION:When a turbocharger (exhaust turbocharger) 15 at the time of low speed in an engine 10 is not worked, an on-off valve 17 is being clouded, so a supercharger 13 is connected to the engine 10 by a solenoid clutch 19 and supercharging takes place. If an engine speed goes up and comes to such a suction air quantity that the turbocharger (exhaust turbocharger) 15 gets working, the on-off valve 17 opens, separating from the solenoid clutch 19, thus the supercharger 13 comes to a stop.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Field of Industrial Application] The present invention relates to a composite supercharging system for an internal combustion engine, which includes an exhaust turbo supercharger and a mechanical supercharger.

[Conventional technology]

Since the exhaust turbo supercharger (turbocharger) does not operate in the low engine speed range, a positive displacement compressor (mechanical supercharger) such as a Roots pump is attached to ensure supercharging in this low speed range. A composite supercharging device is known in which both superchargers are selectively used depending on the rotational speed range to ensure supercharging over substantially the entire rotational speed range.

For example, Japanese Utility Model Application Publication No. 59-67537 discloses a composite supercharging device that performs switching according to the rotational speed.

That is, an on-off valve is installed in the bypass intake passage that bypasses the mechanical supercharger, and is closed when the engine speed is below a certain value, and is closed in the low speed range where the turbocharger does not operate. The system uses an on-off valve to send all intake air to the supercharger for supercharging without bypassing it.

[Problem that the invention seeks to solve]

However, in the above-mentioned combined supercharging system, the switching from the supercharger to the turbocharger is performed according to the rotation speed, so when the rotation speed reaches a predetermined value, the supercharger switches to the turbocharger regardless of whether the turbocharger is operating or not. The charger is inactive (i.e., the on-off valve is opened and the intake air is diverted through the bypass intake passage), and therefore, if the turbocharger is inactive at that point, the connection to the turbocharger is poor and the output is reduced. There is a problem in that, immediately after switching, the amount of power decreases significantly and the required output cannot be obtained until the turbocharger reaches the required operating state. Further, if there is a discontinuity point as described above between the stop of the supercharger and the start of the turbocharger, the output cannot be continued smoothly, causing a shock and significantly impairing drivability.

The purpose of the present invention is to solve the above-mentioned problems (switching from the supercharger to the turbocharger is performed after the turbocharger starts operating, that is, at the time of switching, the supercharger and the turbocharger are always in the N state). The purpose of this system is to prevent problems such as a decrease in output and deterioration of drivability during switching by operating the switch in duplicate.

[Failure to solve the problem]

In order to achieve the above object, according to the present invention, a mechanical supercharger that mainly operates in a low engine speed range and an exhaust turbo supercharger that mainly operates in a high engine speed range are arranged in series in an intake passage. A means is provided for operating the mechanical supercharger only when the intake air F is below a predetermined value.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a composite supercharging device according to the present invention, in which a supercharger 13 such as a Roots pump and a turbocharger 15 are provided in series in an intake passage 11. A part of the intake passage 11 includes a bypass intake passage (hereinafter abbreviated as bypass) that bypasses the supercharger 13.
17 is formed. An on-off valve 21 according to the present invention is provided in the bypass 17, which will be described later. As is well known, the supercharger 13 connects and connects the electromagnetic clutch 19.
The operation and stop of the engine body 10 can be controlled by the disconnection. The combiator 3 connects and disconnects the electromagnetic clutch 19.
Controlled by 0. As is well known, the turbocharger 15 has a compressor 16 disposed in the intake passage 11 and a turbine 8 disposed in the exhaust passage 23, and transmits the rotation of the turbine 18 driven by exhaust gas to the compressor 16 to generate intake air. Performs supercharging. Note that 25 and 27 are a throttle body and a surge tank, respectively, which are arranged in the intake passage.

The actuator 35 that opens and closes the on-off valve 21 is configured, for example, by a step motor driven by the computer 30, but conventionally, as described above, the actuator 35 uses a rotation speed signal SN from a rotation speed sensor (for example, a tachometer, etc.) 39. Since the operating timing of the actuator 35, that is, the opening timing of the on-off valve 21, that is, the operation stop time of the supercharger 13 was determined based on There was a problem in that the supercharger 13 stopped operating.

According to the present invention, in order to solve this problem, the amount of intake air is input into the computer 30 instead of the rotational speed as a signal for controlling the operation stop time of the supercharger, that is, the opening time of the on-off valve 210. This is what I did.

This is based on the fact that the turbocharger only operates when the amount of intake air is above a predetermined value, and by setting the set value of the amount of intake air as a value in the range where the turbocharger can rotate sufficiently, Operation of the supercharger can be stopped once the charger has entered a sufficient rotational operating range. That is, when the engine 10 is rotating at a low speed and the turbocharger 15 is not working, the on-off valve 7 is closed and the supercharger 13 is connected to the engine 10 by the electromagnetic clutch 19 to supercharge the engine. Then, the amount of intake air at which the turbocharger 15 starts working when the engine speed decreases to -L is measured in advance, and this amount of intake air or a larger amount of intake air is set as the set value.

The intake air amount has a relationship with the intake air pressure P and the engine speed N as shown in the map of FIG. In other words, the curve representing the constant intake air meter is shown in FIG. If the supercharger operation stop line is set slightly above the turbocharger supercharging start intake air flow line, the supercharger will stop after the turbocharger operation starts Note that in FIG. 3, the shaded area indicates the supercharging operation area of the supercharger.

Referring to FIG. 4, the intake air pressure PM (Step 401) and the rotation speed N, (Step 402) are detected by the intake pressure sensor 4 and the rotation speed sensor 39, and Po and N.
In step 403), it is determined whether or not both fall within the shaded area of the map shown in FIG.
(When it reaches the supercharger operation stop line on the map shown in the figure), turn off the supercharger. To stop supercharging of the supercharger, open the on-off valve 21 and then open the solenoid flange 19.
It is preferable to do this by moving the on-off valve 2I to the disengaged position, but it is also possible to just open the on-off valve 2I.

After the supercharger stops operating, the supercharging starts only with the turbocharger h.

In the embodiment shown in FIG. 1, the amount of intake air is determined by measuring the rotational speed and the intake air pressure, but if an air flow meter 29 is provided in the intake passage 11, the air flow rate is determined as shown in FIG. The intake air amount signal Sa, which can be directly detected by the make 29, may be input to the computer 30. Therefore, in this second embodiment, neither an intake pressure sensor nor a rotation speed is necessary.

〔Effect of the invention〕

As described above, according to the present invention, the supercharger stops operating after the turbocharger starts the JJ operation, so the transition from the supercharger to the turbocharger is smooth, and the output at the time of transition is significantly reduced. There is no temporary decline and therefore no shock associated with it.

[Brief explanation of drawings]

FIG. 1 is an illustrative diagram showing the overall structure of a composite supercharging device according to the present invention, FIG. 2 is a diagram similar to FIG. 1 showing a different embodiment from FIG. 1, and FIG. 3 is an illustration of the intake air amount. FIG. 4 is a map diagram showing the relationship between intake air pressure and rotational speed with constant . FIG. 4 is a diagram showing an operation flow chart of the supercharging device according to the present invention. 11...Intake passage, 13...Supercharger h 15...Turbocharger\17...Bypass path, 21...Opening/closing valve. 11゛...Intake passage 13...Supercharger 15...Turbocharger 17°°° Bi-gas passage 21...Opening/closing square

Claims (1)

[Claims] A mechanical supercharger that operates mainly in the low engine speed range and an exhaust turbo supercharger that mainly operates in the high engine speed range are arranged in series in the intake passage, and the above-mentioned A composite supercharging device for an internal combustion engine, characterized in that it is provided with means for operating a mechanical supercharger.