JPH05113124A - Internal combustion engine having mechanical supercharger - Google Patents

Abstract

PURPOSE:To reduce change of torque when failure occurs at a bypass control valve by connecting and disconnecting a solenoid clutch which enables connecting and disconnecting of a mechanical supercharger when operation failure is detected at the bypass control valve arranged in a bypass passage which bypasses the mechanical supercharger. CONSTITUTION:A bypass passage 8 is connected to an intake passage 3, on the down stream side of a throttle valve 5, for bypassing a mechanical supercharger. A bypass control valve 10 driven by a stepper motor 9 is arranged in the bypass passage 8. Crank pulleys are connected to the mechanical supercharger 4 through a driving belt 11 and a solenoid clutch 12. The crank pulley is connected and disconnected to and from the mechanical superchargers 2, 4 by connecting and disconnecting the solenoid clutch 12. When operation failure of the bypass control valve 10 is detected, the connection/disconnection are performed under a specified condition. Change of torque, including its abrupt rising and falling, is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine having a mechanical supercharger.

[0002]

2. Description of the Related Art In recent years, there has been a demand for higher engine output, and for this reason, engines having a supercharger have been provided. As this supercharger, an exhaust turbine supercharger driven by utilizing exhaust gas is generally used, but a mechanical supercharger driven by rotation of an engine is also widely used.

An engine having such a mechanical supercharger is usually equipped with a mechanical supercharger on the downstream side of the throttle valve in the intake passage, as described in JP-A-62-276220. A bypass passage is provided, and the bypass control valve in this passage is opened / closed to control the supercharging pressure by the mechanical supercharger.

Further, the mechanical supercharger is superior in response to the exhaust turbine supercharger, but the rotation of the engine is used for driving the exhaust supercharger, so that the output loss of the engine is involved. As a result, only when the operating condition requires high torque,
It is preferable to drive a mechanical supercharger, for which
An engine having such a mechanical supercharger is provided with an electromagnetic clutch that enables connection and disconnection between the mechanical supercharger and the engine.

The above-mentioned bypass control valve is normally fully opened to prevent sudden supercharging and sudden torque increase when the electromagnetic clutch is connected and the mechanical supercharger is driven. The torque is smoothly increased by being brought into the state and then gradually closed according to the load.

[0006]

In the engine having the above-mentioned mechanical supercharger, when the bypass control valve fails and does not move, when the operation is stopped at the opening on the closing side (hereinafter, closing failure), When the electromagnetic clutch is connected, the torque suddenly rises and the vehicle accelerates more than necessary, deteriorating the drivability and causing an operation failure at the opening (opening failure). Even if the feeder is driven, supercharging is not performed, the torque cannot be increased, and conversely, the output loss of the engine occurs due to the driving, so the generated torque is reduced.

Therefore, an object of the present invention is to provide an internal combustion engine capable of reducing a change in torque including a rapid increase and a decrease in torque even when a bypass control valve fails.

[0008]

In order to achieve the above object, an internal combustion engine with a mechanical supercharger according to the present invention comprises a bypass passage for bypassing the mechanical supercharger in an intake passage,
An internal combustion engine with a mechanical supercharger, comprising: a bypass control valve provided in the bypass passage; and a clutch that enables connection and disconnection between the mechanical supercharger and a drive shaft of the internal combustion engine. Failure detection means for detecting an operation failure of the control valve, and when the failure detection means does not detect an operation failure of the bypass control valve, the clutch is disengaged as a first discontinuity condition according to an operating state of the internal combustion engine. When the operation failure of the bypass control valve is detected, the second disengagement condition that makes it possible to reduce the torque change as compared with the case where the clutch is discontinued according to the first discontinuity condition. And an engagement / disconnection condition switching means for the clutch.

[0009]

Even if the bypass control valve fails, the clutch disengagement is controlled according to the first disengagement condition based on the operating state of the internal combustion engine, which causes problems such as deterioration of drivability and reduction of generated torque. However, according to the internal combustion engine with a mechanical supercharger according to the present invention,
By detecting the failure of the bypass control valve by the failure detection means,
At that time, the clutch can be engaged and disengaged according to the second engagement / disengagement condition that can reduce the torque change, as compared with the case of complying with the first engagement / disengagement condition. Good operating conditions can be obtained.

[0010]

1 is a schematic view showing an embodiment of an internal combustion engine with a mechanical supercharger according to the present invention. In the figure, 1 is an engine, 2 is a crank pulley attached to the drive shaft of the engine 1, 3 is an intake passage, 4 is a mechanical supercharger provided in the intake passage, and 5 is a mechanical type of the intake passage 3. A throttle valve provided upstream of the supercharger 4, 6 is an air flow meter provided upstream of the throttle valve 5, and 7 is an exhaust passage.

A bypass passage 8 for bypassing the mechanical supercharger 4 is connected to the intake passage 3 downstream of the throttle valve 5, and a bypass control valve driven by a stepper motor 9 is provided in the bypass passage 8. 10 are provided. The crank pulley 2 and the mechanical supercharger 4 are connected via a drive belt 11 and an electromagnetic clutch 12,
By controlling the on / off of the electromagnetic clutch 12, it is possible to connect / disconnect between the two and 4.

The control computer 13 has a rotation sensor (not shown) for detecting the rotation speed of the engine 1 from the crank pulley 2 and an opening sensor (not shown) for the throttle valve 5.
, An air flow meter 6, an opening sensor (not shown) of the bypass control valve 10, an exhaust temperature sensor (not shown), etc., and are electrically connected to judge the operating state of the engine 1. Accordingly, the ignition timing, the fuel injection amount, and the like are basically controlled, and the stepper motor 9 and the electromagnetic clutch 12 that drive the bypass control valve 10 are controlled.

The stepper motor 9 is connected with the electromagnetic clutch 12 as the load of the engine 1 increases, and when the mechanical supercharger is driven, the stepper motor 9 has a bypass control valve for preventing a rapid torque increase of the engine. Hold 10 in the fully open position,
After that, the bypass control valve 10 is controlled to move to a position where the supercharging pressure is optimum according to the load of the engine 1. For example, the opening degree of the bypass control valve 10 is controlled based on the load-bypass control valve 10 opening degree θ relationship curve as shown in FIG. Note that C / ON in FIG. 4 is a load value to which the clutch 12 is connected, and this value may have hysteresis.

However, when the bypass control valve 10 malfunctions, in the case of a closing failure, the torque suddenly increases at the same time as the electromagnetic clutch 12 is connected, and the vehicle is accelerated more than necessary. In the case of deterioration and open failure, no matter how much the mechanical supercharger 4 is driven, supercharging is not performed, the torque cannot be increased, and conversely, output loss of the engine occurs due to driving, Generated torque is reduced.

In order to solve these problems, the internal combustion engine with a mechanical supercharger of this embodiment is provided with a control computer 13.
Thus, according to the flowchart shown in FIG. 2, the opening / closing control of the bypass control valve 10 and the on / off control of the electromagnetic clutch are performed via the stepper motor 9.

In this flowchart, firstly, the operating state of the engine 1 is detected by the signals from the respective sensors (step 110), and secondly, the optimum opening degree θ of the bypass control valve 10 in this operating state is calculated ( Step 120),
Thirdly, the bypass control valve 10 is operated based on the calculated value θ (step 130), and fourthly, the actual opening θ ′ of the bypass control valve 10 after the operation is read by the opening sensor (step 140). ).

Next, at step 150, the calculated value θ of the opening degree of the bypass control valve 10 and the measured value θ ′ are compared,
If they are equal, it is determined that the bypass control valve 10 has not failed, and if they are not equal, it is determined that the bypass control valve 10 has failed, and the routine proceeds to step 170.

At step 160, the first step shown in FIG.
According to the map, in step 170, the electromagnetic clutch 12 is intermittently controlled according to the second map shown in FIG.

The first map shown in FIG. 3A shows the ratio Q / N of the intake air amount Q measured by the air flow meter 6 and the rotation speed N of the engine 1 measured by the rotation sensor as the engine load. Is a map for intermittently controlling the electromagnetic clutch based on this value Q / N and the engine speed N, and is a general map for connecting the electromagnetic clutch 12 when the load Q / N becomes high and supercharging is required. Is used for.

Therefore, when the bypass control valve is not in failure, the opening / closing control of the bypass control valve is surely performed by repeating this flow, and a good operating condition can be obtained as in the conventional case.

The second map shown in FIG. 3 (B) is a map for controlling the on / off of the electromagnetic clutch by the load Q / N and the actual opening θ'of the bypass control valve 10 at the time of failure. In the map, when the bypass control valve 10 fails at a predetermined opening or more, the electromagnetic clutch 12 is always disengaged regardless of the load Q / N. At this time, no matter how much the mechanical supercharger 4 is driven, the supercharging pressure does not rise so much that the torque cannot be improved, and the electromagnetic clutch 12 is disengaged to prevent the output loss of the engine due to the driving.

When the bypass control valve 10 fails at a predetermined opening or less, the electromagnetic clutch 12 when the load Q / N is in the middle and high speed rotation in the normal first map shown in FIG. 3 (A).
The electromagnetic clutch 12 is connected at a time point lower than the load for connecting. As a result, the torque immediately increases when the electromagnetic clutch 12 is connected, but the amount of increase in the torque is small because the absolute value of the load when the electromagnetic clutch 12 is connected is small.
It can be kept small, and the deterioration of the conventional drivability is improved.

Further, since the ratio of the above-mentioned torque increase portion increases as the failure opening degree of the bypass control valve 10 approaches the fully closed state, as shown in the second map shown in FIG. If the connected load Q / N is lowered as the failure opening approaches full closure, the above-mentioned torque increase is further reduced, and a drivability similar to that when the bypass control valve 10 is not broken is obtained. Be done.

If the bypass control valve 10 is also used for the upper limit control of the supercharging pressure, the control for disconnecting the electromagnetic clutch 12 at the time when the supercharging pressure reaches the upper limit value, especially at the time of closing failure, By further performing it, in addition to the above-described effect of the second map, it is possible to prevent excessive boost pressure.

In the second map of this embodiment, a relatively good operating condition can be obtained regardless of whether the bypass control valve 10 is open or closed, but a map that improves either one is used. However, it is clear that a better operating condition than the conventional one can be obtained. For example, when the bypass control valve 10 fails regardless of the open failure and the closed failure,
Even with the control such that the electromagnetic clutch 12 is disengaged, the problem of torque decrease due to open failure and the problem of excessive boost pressure can be solved.

[0026]

As described above, according to the internal combustion engine with a mechanical supercharger according to the present invention, when the bypass control valve fails, the second map different from the normally used first map is used.
By controlling the electromagnetic clutch that enables the mechanical turbocharger to be engaged and disengaged, and using the above-mentioned second map as this second map, deterioration of drivability due to a sudden torque increase that has conventionally occurred at the time of closing failure and occurrence of opening failure occur The problems such as the decrease in torque that have been solved are solved, and in addition to the good operating condition when the bypass control valve is normal, even when the bypass control valve fails, a considerably better operating condition than before can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an internal combustion engine with a mechanical supercharger according to the present invention.

FIG. 2 is a flowchart for performing opening / closing control of a bypass control valve and intermittent control of an electromagnetic clutch.

FIG. 3 is an intermittent control map of the electromagnetic clutch used in the flowchart of FIG. 2, where (A) is a normal state of the bypass control valve and (B) is a fault state.

FIG. 4 is a graph showing the relationship between the opening degree of the bypass control valve and the load.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 4 ... Mechanical supercharger 8 ... Bypass passage 10 ... Bypass control valve 12 ... Electromagnetic clutch 13 ... Control computer

Claims (1)

[Claims] 1. A bypass passage for bypassing a mechanical supercharger in an intake passage, a bypass control valve provided in the bypass passage, and a bypass control valve between the mechanical supercharger and a drive shaft of an internal combustion engine. In an internal combustion engine with a mechanical supercharger that includes a clutch that enables and disconnects, when failure detection means for detecting an operation failure of the bypass control valve and operation failure of the bypass control valve is not detected by the failure detection means The clutch is disengaged according to a first disengagement condition according to the operating state of the internal combustion engine, and when an operation failure of the bypass control valve is detected, the clutch is disengaged under the first discontinuity condition. And a clutch engagement / disconnection condition switching means for performing a second engagement / disengagement condition that makes it possible to reduce a torque change as compared with the case of the above. Internal combustion engine with a feeder.