JPS61291729A - 2-step type supercharging device - Google Patents

Abstract

PURPOSE:To smoothly shift the operation mode of a supercharger and to improve the efficiency of an engine, by a method wherein control is effected so that the supercharge pressure of a bypass valve is adjusted to a desired value. CONSTITUTION:During low rotation speed running of an engine, a turbocharger 3 and a supercharger 4 are rendered operative. When a rotation speed is increased and exceeds the intersept rotation speed of the turbocharger 3, an electromagnetic valve 4 is released, and the action of the supercharger is rendered ineffective. Control of an electromagnetic valve 28 is effected as follows. When an electomagnetic clutch 15 is engaged, a desired supercharge pressure is determined based on a throttle opening, and the rotation speed of an engine. A desired supercharge pressure and an actual supercharge pressure are so set as to be within the width of an insensitive band. Thereafter, a temperature correction value and a pressure correction value are added to determine the final duty ratio of the electromagnetic valve 28.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an internal combustion engine in which a turbocharger, a supercharger, and a charge V are connected in series with each other to enable suitable supercharging over a wide operating range. This invention relates to a two-stage supercharging device for engines.

<Prior Art> Conventionally, a so-called turbocharger, which uses the exhaust flow of an engine as a driving source, has been widely used to increase the output of an engine. In general, boost pressure increases as the engine speed and load increase, but overcharging more than necessary can cause problems such as knocking, so when boost pressure reaches a certain level, The increase in supercharging pressure is suppressed by opening the wastegate valve of the feeder as appropriate. Such a pressure is called an intercept pressure, and the engine operating conditions that generate such an intercept pressure are called an intercept point.

In designing a supercharger, not only the intercept pressure but also the level at which the intercept point is set are important factors. When the intercept rotation speed is set relatively low, the supercharging effect increases in the low speed range, but there is a disadvantage that engine loss increases in the high rotation speed range. Conversely, when the intercept rotation speed is set relatively high, engine loss in the high rotation speed range is reduced, but the supercharging effect in the low speed range becomes insufficient.

<Problems to be Solved by the Invention> Therefore, it is conceivable to connect two superchargers in series to realize suitable supercharging pressure over a wide rotational speed range.

In other words, in the low engine speed range, supercharging is performed by a supercharger that can generate boost pressure from a relatively low engine speed range, and in the high engine speed range, the interceptor is used exclusively. Supercharging can be performed by a supercharger with a relatively high rotational speed.

In particular, when a turbocharger-type supercharger is used in conjunction with a so-called supercharger that uses the engine's shaft output as a driving source, there is an advantage that the supercharger can generate a relatively high boost pressure from a relatively low rotational speed. It will be done. For example, by appropriately determining the gear ratio of the driving portion of the supercharger, it is possible to achieve a sufficient supercharging effect from an extremely low speed range.

In that case, the rotational speed of the supercharger may become excessive in the high-speed range, which may cause problems with durability or cause overcharging, which may impair the engine's power performance. This problem can be solved by providing a clutch in the supercharger and cutting off the drive of the supercharger at high speeds. In addition, in order to eliminate the inconvenience that one of the turbochargers can cause flow resistance in the intake passage, placing a burden on the engine and increasing engine loss, it is necessary to install a bypass passage in the turbocharger. A bypass valve provided inside the bypass valve may be fully opened.

However, when using a supercharger and a turbocharger together as described above, if engine usability is considered, it is possible to smoothly transition between a mode in which both are operated and a mode in which only the turbocharger is operated. It is necessary to

In particular, the question of superchargers and turbochargers is
Since there are differences in control characteristics for various parameters and turbochargers are generally controlled by wastegate valves, it is desirable to be able to control the supercharger appropriately.

The present invention was made in view of the above circumstances, and its main purpose is to provide a two-stage supercharging device that can smoothly achieve suitable supercharging pressure over a wide operating range of the engine. It is about providing.

Means for Solving the Problems According to the present invention, such an objective is to provide a first supercharger driven by the exhaust flow of an internal combustion engine, and a first supercharger driven by the shaft output of the internal combustion engine. In the two-stage supercharging device for an internal combustion engine, the second supercharger is connected in series with each other to enable suitable supercharging over a wide operating range. , a bypass passage that communicates an outlet and an inlet of the supercharger, a bypass valve provided in the bypass passage, and a clutch that cuts off and on the supply of the shaft output to the supercharger; This is achieved by providing a two-stage supercharging device in which a valve is controlled to open and close to achieve a target supercharging pressure.

In this way, sufficient supercharging pressure can be generated from a relatively low engine speed due to the action of the supercharger, which can generate a considerable amount of supercharging pressure from a relatively low engine speed range. Moreover, the change in supercharging pressure with respect to rotational speed is smoothed.

In particular, by providing compensation based on changes in atmospheric conditions, efficient operation of the internal combustion engine is always achieved.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows the entire two-stage supercharging device according to the invention. Generally, in order to supercharge the intake air to be supplied to the engine 1, intake air introduced from an air cleaner 2 is supercharged by a turbocharger 3 and a supercharger 4 connected in series on the downstream side thereof. It has become.

Air introduced from the air cleaner 2 is introduced into the intake port 5 of the turbocharger 3, compressed by the compressor 6, and sent out to the passage 11.

A compressor 6 of the turbocharger 3 is connected to an exhaust turbine 8 via a rotating shaft 7, and the exhaust turbine 8 is driven by exhaust gas sent out from an exhaust pipe 9 of the engine 1. The exhaust gas is discharged from the exhaust pipe 10 after driving the exhaust turbine 8, but by opening the waste l-gate valve 11 as necessary, the exhaust gas bypasses the exhaust turbine 8 and is discharged from the exhaust pipe 10. You can also send it to

A passage 12 connected to the outlet of the compressor 6 is connected to the inlet of the supercharger 4. The supercharger 4 receives power from the output shaft of the engine 1 via a belt 13, and is capable of intermittent power supply to the rotor 15 by an electromagnetic clutch 14 attached to a pulley on the side of the supercharger 4. I'm looking forward to it. The outlet of the supercharger 4 reaches the intake pipe of the engine 1 via a passage 16, and a throttle valve 17 and a fuel injection device 19 are provided in the intake pipe on the downstream side thereof.

The inlet passage 12 and the outlet passage 16 of the supercharger 4 are connected by a bypass passage 20, and a bypass valve 21 is provided in the bypass passage. This bypass valve 21 is connected to the working end of a diaphragm actuator 22, which includes a passage 25, a solenoid valve 2
4 and a passage 23 to the intake pipe 18 downstream of the throttle valve 17 . The bypass valve 21 is also connected to the working end of another diaphragm actuator 26, which is connected via a passage 29, a solenoid valve 28 and a passage 27 to the outlet passage 1 of the supercharger 4.
6. Solenoid valves 24 and 28 are connected to line 3, respectively.
It is connected to the control device 33 via 0131. Furthermore, the control device 33 can also control the engagement and engagement of the electromagnetic clutch 14 via the line 32.

The 'i4 magnetic clamp 14 is released when the engine speed exceeds a predetermined level (FIG. 2). By doing so, when the turbocharger is generating sufficient boost pressure, the problem of the supercharger becoming a flow path resistance in the intake passage and causing durability problems is eliminated. Ru.

In some cases, not only when the engine speed exceeds a predetermined level, but also when the engine load is smaller than a predetermined value, that is, when the suction negative pressure P8 downstream of the throttle valve is larger than a predetermined value (for example, PB <760sHU
), the electromagnetic clutch 14 is also released, and in addition to solving the above-mentioned problem, it is also possible to prevent supercharging when the engine load is small.

FIG. 3 is a flowchart showing the opening/closing conditions for the N magnetic valve 24.

When the electromagnetic clutch 14 is off (ST21), the solenoid of the electromagnetic valve 24 is operated under the condition that, for example, the pressure on the downstream side of the throttle valve P 8 < 760 mmH'J (ST2
2) After demagnetization, engine intake negative pressure is introduced into the diaphragm actuator 22 (ST24), and PB≧76.
Under the condition of 0stlg (ST22), the solenoid is excited and atmospheric pressure is introduced into the diaphragm actuator 22 (ST25).

? ! When the magnetic clutch 14 is on (ST21), the solenoid of the solenoid valve 24 is activated, for example, under the condition that the pressure on the upstream side of the throttle valve P2 < 760stl (II).
23) Atmospheric pressure is introduced into the diaphragm actuator 22 after being excited (ST25), and P2≧760stIO
Under these conditions (ST23), the solenoid is demagnetized and PB is introduced into the diaphragm actuator 22 (ST24).

Therefore, when the electromagnetic clutch 15 is off, that is, the operation of the supercharger 4 is stopped; rather, the operation of the supercharger 4 is stopped.
If P B < 760 mm HQ, engine intake negative pressure P8 is introduced into the diaphragm actuator 22, the bypass valve 21 is fully opened, and PB≧760 a
In the case of HO, the supercharging pressure P2 is introduced into the other diaphragm actuator 26, so the bypass valve 21 is also fully opened, and in either case, the supercharger 4
does not become a flow path resistance in the intake passage.

Further, when the engine is under low load, the solenoid of the solenoid valve 28 is controlled in duty ratio, the bypass valve 21 is opened to an appropriate degree, and supercharging pressure is realized in accordance with the throttle opening and the rotational speed of the engine.

That is, the solenoid of the electromagnetic valve 28 is energized when the electromagnetic clutch 15 is off, and the solenoid of the diaphragm actuator 2
6, P2 is introduced. When the electromagnetic clutch 15 is on, the duty ratio of the solenoid is controlled by the control device 33, the bypass valve 21 is set to an appropriate half-open state, and the supercharger 4 and turbocharger 3 are switched from the 01 mode, that is, from the low speed range. , to smooth the change in supercharging pressure in a mode in which only the turbocharger 3 is used, that is, in a transition region to a high speed region.

FIG. 4 is a flowchart showing the flow of duty ratio control of the solenoid valve 28.

Following program start (ST1), electromagnetic clutch 1
5 is ON or OFF (ST2), and if the electromagnetic clutch is ON, the target value P' of P2' is determined based on the throttle opening θth and engine rotational speed N8 at that time.
is set (ST3).

The difference ΔP2' between ref P2'ref and the actual supercharging pressure P2' is determined (ST4), and the basic, ie, uncorrected duty ratio DBV)I is set (ST5).

Next, if the absolute value of ΔP2' exceeds the dead zone width GBV range (ST6), the duty ratio is changed by multiplying ΔP2' by a correction value KBV determined by the engine rotational speed Ne (ST8). ) Proceed to 3T9. 3T6
If it is determined that ΔP2' is within the predetermined dead zone, the process proceeds to ST9 without changing the duty ratio.

In ST9 and 5T10, a humidity correction value KBTA and a pressure correction value KSPA are determined. This is preferably done by searching a one-dimensional table stored in a ROM attached to the OPU. Next, calculate the integral control constant DBV by considering these correction values (ST11). At this time, DBV and DBI must be in the range of 0 to 100%, so these values should be kept within these ranges and (ST12), outputs DBV in the next 5T13, determines the final duty ratio, and returns to ST2 again.

If it is determined in ST2 that the electromagnetic clutch is OFF, the bypass valve should be fully opened, so 5T
In step 14, DBV and DB□ are set to O, and the process returns to ST2 again via 5T13.

FIG. 5 shows the engine rotational speed N when the throttle valve 17 is fully open and 3/8 open. The diagram does not show the change in supercharging pressure P2' and the opening degree of the bypass valve 21. The horizontal axis shows the engine rotational speed (-line margin) degree N8, and point A shows the intercept rotational speed of the turbocharger. The vertical axis represents supercharging pressure P2' and bypass valve opening degree. In the low rotational speed range of the engine, both the turbocharger 3 and the supercharger 4 are in operation, and in particular, due to the supercharging action of the supercharger V in the low rotational speed range, curves B and B' indicate As shown in the figure, the boost pressure gradually increases from a relatively low rotational speed range as the engine rotational speed increases.

When the rotational speed of the engine reaches the vicinity of the intercept rotational speed A of the turbocharger 3, the bypass valve 21 is gradually closed, and the increase in supercharging pressure reaches its limit. When the rotational speed is further increased to exceed the intercept rotational speed of the turbocharger 3, the electromagnetic clutch 4 is released and the supercharger 4 loses its action completely, as shown by point c1c'. However, since the supercharging pressure by the turbocharger 3 is sufficiently high, the necessary supercharging pressure is secured only by the turbocharger 3, as shown by the curve D'.

As clearly shown in FIG. 5, if the conditions for opening the bypass valve 21 and the conditions for releasing the electromagnetic clutch 4 of the supercharger 4 are appropriately set, curves B and B' can be smoothly curved, and D' can be curved smoothly. It can be seen that the feeling or response of the engine can be improved.

In the above embodiment, a diaphragm actuator using either supercharging pressure or intake negative pressure as a driving source is used to control opening and closing of the bypass valve, and drive control of the supercharger is performed by turning on and off an electromagnetic clutch. However, the control device can also drive a pulse motor to open and close the bypass valve, or use a hydraulic clutch to control the drive of the supercharger.

<Effects of the Invention> As described above, according to the present invention, by using a supercharger and a turbocharger together, sufficient supercharging pressure can be obtained from a relatively low rotational speed, and moreover, it is possible to obtain sufficient supercharging pressure at a relatively low rotational speed. In this case, the function of the supercharger is stopped, and if necessary, the supercharger is prevented from being a burden on the engine, and the transition of the operating mode of the supercharger is performed smoothly, thereby improving the efficiency of the engine. ,
Moreover, it can have an extremely large effect in improving the response.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the configuration of a two-stage supercharging device according to the present invention. FIG. 2 is a flowchart showing the conditions for turning on and off the N magnetic latch. FIG. 3 is a flowchart showing the opening/closing conditions of the electromagnetic valve for controlling the opening/closing of the bypass valve. FIG. 4 is a flowchart showing the flow of duty ratio control for adjusting the opening degree of the bypass valve. FIG. 5 is a graph showing changes in supercharging pressure and bypass valve opening degree with respect to engine rotational speed. 1...Engine 2...Air cleaner 3...
・Turbocharger 4...Supercharger 5...
Inlet 6...Compressor 7...Rotating shaft 8...Exhaust turbine 9.10...Exhaust pipe 11...Wastegate valve 12...Passage
13... Belt 14... Electromagnetic clutch 15.
... Rotor 16 ... Passage 17 ... Throttle valve 18 ... Intake pipe 19 ... Fuel injection device 20 ... Bypass passage 21 ... Bypass valve 22
...Diaphragm actuator 23...Passage
24... Solenoid valve 25... Passage 26... Diaphragm actuator 27... Passage 28... Solenoid valve 29... Passage
30 to 32... Line 33... Control device patent applicant: Honda Motor Co., Ltd. representative Patent attorney: Yo Oshima - Figure 2 Figure 3

Claims (4)

[Claims] (1) A first supercharger driven by the exhaust flow of an internal combustion engine and a second supercharger driven by the shaft output of the internal combustion engine are connected in series to each other over a wide operating range. In a two-stage supercharging device for an internal combustion engine capable of suitably supercharging, the second supercharger includes a bypass passage communicating an outlet and an inlet of the supercharger, and a bypass passage. It has a bypass valve provided therein, and a clutch that connects and disconnects the supply of the shaft output to the supercharger, and the bypass valve is controlled to open and close so as to achieve a target supercharging pressure. Two-stage supercharging device. (2) The two-stage supercharging device according to claim 1, wherein the target supercharging pressure is corrected based on at least one of air temperature and atmospheric pressure. (3) The bypass valve is controlled to open and close by an actuator whose driving sources are boost pressure and intake negative pressure.
Staged supercharging device. (4) The two-stage supercharging device according to claim 1 or 2, wherein the bypass valve is controlled to open and close by a pulse motor.